Image forming apparatus and image forming system having a controller that controls a rubbing treatment for a fixing roller of a replaceable fixing portion

An image forming apparatus has an image forming station, a mounting portion, and a fixing portion that includes a first rotatable member, a second rotatable member, a rubbing rotatable member configured to rub a surface of the first rotatable member during a rubbing treatment, and a storing portion capable of storing number information. A number of recording materials fed to the fixing portion is counted, written into the storing portion, and used to determine whether to execute the rubbing treatment. In a case in which, in sequence, the recording material is fed to the mounted fixing portion, the mounted fixing portion is removed and replaced with another fixing portion, and the removed fixing portion is remounted, both number information acquired from the storing portion and the number of recording materials fed to the remounted fixing portion are used to determine whether to execute the rubbing treatment.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to an electrophotographic type image forming apparatus and an electrophotographic type image forming system.

The electrophotographic type image forming apparatus comprises a fixing device (fixing portion) for fixing the toner image on a recording material. It is known to replace the fixing device depending on the size and/or kind of the recording material for the purpose of high quality prints. Japanese Laid-open Patent Application 2011-56945, for example, proposes that identifying information of the fixing device is detected, and when the fixing device is not proper for the requirements of the printing job to be performed, the user is notified of the fact.

On the other hand, when an unfixed toner image is fixed in a fixing device, a widthwise edge of the recording material (an edge at an end portion of the recording material with respect to a direction perpendicular to a feeding direction of the recording material) contacts a rotatable member with the result of fine scores of the surface of the fixing member. When such damage occurs on the same position of the fixing member, the surface property of the fixing member at the portion becomes coarse as compared with the other portion of the fixing member, and there is a liability that the unevenness in glossiness appears on the image of the recording material having been subjected to the fixing process. Therefore, it is known that the surface of the fixing member is rubbed by a rubbing rotatable member (fixing refresh operation) each time that a predetermined number of the recording materials is processed by the fixing member, by which the surface property of the fixing member is uniformized (Japanese Laid-open Patent Application 2008-40364).

However, when a system is employed in which a plurality of fixing devices are exchanged and used for the image fixing operation, the counting of the processed recording materials may not be proper for the fixing refresh operation, and the fixing refresh operation may not be carried out at proper timing. As a result, the glossiness non-uniformity of the output image may not be avoidable.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an image forming apparatus, an image forming system and a fixing device, with which the image quality is maintained even in the case that the fixing device is replaceable.

According to an aspect of the present invention, there is provided an image forming apparatus comprising an image forming station configured to form an unfixed toner image on a recording material; a mounting portion configured to mount one of a plurality of fixing devices each including a first rotatable member and a second rotatable member which cooperate with each other to form a nip for fixing the unfixed toner image on the recording material fed from said image forming station, a rubbing rotatable member configured to rub a surface of said first rotatable member, and a storing portion capable of storing information; a counter configured to count recording materials fed to said fixing device mounted on said mounting portion and to store number information indicative of the number counted by said counter in said storing portion of said fixing device mounted on said mounting portion; and an executing portion configured to execute a rubbing treatment of a rubbing rotatable member to said first rotatable member of the fixing device mounted on said mounting portion, when the number counted by said counter on the basis of the number information acquired from said storing portion of said fixing device mounted on said mounting portion exceeds a predetermined number.

According to another aspect of the present invention, there is provided an image forming system comprising an image forming apparatus including an image forming station configured to form an unfixed toner image on a recording material; a mounting portion configured to mount one of a plurality of fixing devices each including a first rotatable member and a second rotatable member which cooperate with each other to form a nip for fixing the unfixed toner image on the recording material fed from said image forming station, a rubbing rotatable member configured to rub a surface of said first rotatable member, and a discrimination portion indicative of identifying information for discriminating said fixing device from another fixing device; and a counter configured to count the recording materials fed to said fixing device mounted on said mounting portion; and a storing device configured to store number information indicative of the number counted by said counter, in correlation with the identifying information, wherein said counter counts the recording materials fed to said fixing device mounted on said mounting portion, on the basis of the number information stored in said storing device in correlation with the identifying information of said fixing device mounted on said mounting portion, and wherein said image forming apparatus executes a rubbing treatment of a rubbing rotatable member to said first rotatable member of the fixing device mounted on said mounting portion, when the number counted by said counter exceeds a predetermined number.

According to a further aspect of the present invention, there is provided an image forming apparatus comprising an image forming station configured to form an unfixed toner image on a recording material; a mounting portion configured to mount one of fixing devices each including a first rotatable member and a second rotatable member which cooperate with each other to form a nip for fixing the unfixed toner image on the recording material fed from said image forming station, a discrimination portion indicative of identifying information for discriminating said fixing device from another fixing device mountable on said mounting portion in place of said fixing device mounted on said mounting portion, a rubbing rotatable member configured to rub a surface of said first rotatable member, and a fixing device storing portion capable of storing information; a counter configured to count the recording materials fed to said fixing portion mounted on said mounting portion; a main assembly storing portion capable of storing information; a writing portion configured to write the number information indicative of the number counted by said counter in said main assembly storing portion in correlation with the identifying information and to write the number information in said fixing device storing portion; and an executing portion configured to execute a rubbing treatment of a rubbing rotatable member to said first rotatable member of the fixing device mounted on said mounting portion, when the number counted by said counter on the basis of the information acquired from said fixing storing portion and said main assembly storing portion exceeds a predetermined number.

DESCRIPTION OF THE EMBODIMENTS

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings. The structures of the embodiments are examples, to which the present invention is not limited.

(1. General Arrangement of Image Forming Apparatus)

FIG. 1is a sectional view of an example of an image forming apparatus.

The general arrangement of the image forming apparatus100will be described.

The image forming apparatus100feeds a recording material102from a recording material accommodating portion103into an image forming station309(FIG. 2) to form a toner image on the recording material102. The details of the image forming station309will be described hereinafter.

Thereafter, the image forming apparatus100feeds the recording material102carrying the formed toner image to a fixing portion (first fixing device150and second fixing device170), where the toner image is fixed on the recording material102by heat and pressure. The details of the fixing portion will be described hereinafter.

In the case of a one-side printing operation, the recording material102having the fixed image is guided into the discharging path139by a flapper132and is discharged to an outside of the image forming apparatus100.

On the other hand, in the case of a two-side printing operation, the image forming apparatus100reverses the recording material102already having the image on one side and refeeds it into the image forming station309. More particularly, the flapper132guides the recording material102having departed the fixing device into a feeding path134and then into a reversing portion136. When a reversion sensor135detects a trailing edge of the recording material102, a flapper133switches the recording material feeding direction to a feeding path137. The image forming apparatus100refeeds the reversed recording material102into the image forming station309and the fixing portion through the feeding path137.

The recording material102having been subjected to the image forming operations and the respective sides is fed by the flapper132into the discharging path139, and then is discharged to the outside of the image forming apparatus100.

The flapper132is a switching member for switching the feeding of the recording material102having passed through the image forming station309and the fixing portion between the feeding path134and the outside of the image forming apparatus100.

The recording material102may be paper, OHP sheet, or the like, on which the image is to be formed by the image forming apparatus100.

An operating portion180functioning as a notifying portion, a selector, a setting portion and/or a receiving portion, and is provided with a display screen and a selection key. The operating portion180displays the status of the image forming apparatus100on the display screen, and receives the instructions from the operator by the selection keys. Examples of the operation include setting of a kind of recording material (surface property, basis weight, size or the like), setting of the number of the prints, setting of the single-sided printing or double-sided printing, or the like.

The main switch101is a starting switch for actuating the image forming apparatus100.

The front door140as an opening and closing portion is provided for the opening of the main assembly of the image forming apparatus100for mounting a fixing device (first fixing device150, second fixing device170) to a mounting portion (first mounting portion141, second mounting portion142).

The image forming apparatus100is provided with an opening and closing sensor (optical sensor)305(FIG. 2) as a sensor for sensing a closed state of the front door140. The opening and closing sensor305and a CPU301(FIG. 2) function as an opening and closing detecting portion. The front door140is provided with a projection (unshown), which is inserted into a receiving portion (unshown) of the main assembly100A of the image forming apparatus100by the closing of the front door140. The CPU301detects the closing of the front door140on the basis of a signal produced by the opening and closing sensor305upon the insertion of the projection into the receiving portion. On the other hand, when no output signal is produced by the opening and closing sensor305, the CPU301detects that the front door140is open. In an alternative structure, the CPU301detects the opening of the front door140on the basis of the signal produced by the opening and closing sensor305upon the opening of the front door140, and the CPU301detects that the front door140is closed when the signal from the sensor305is not detected.

(2. Structure of Control System)

FIG. 2is a block diagram of a control system.

The image forming apparatus100(FIG. 1) is provided with the CPU301, a RAM302, and a ROM303for controlling the operation of the image forming apparatus100.

The CPU301functioning as a controller carries out a basic control of the image forming apparatus100by executing control programs stored in the ROM303. The CPU301uses the RAM302as a work area for executing the processing of a control program.

The CPU301is electrically connected with the RAM302and the ROM303, and various mechanisms to be controlled.

In addition, the CPU301functions also as a counter for counting the recording materials102fed into the first fixing device150or second fixing device170. The specific structure will be described hereinafter.

An external I/F portion304is a communication circuit for communication with an external device connected through a network (LAN and/or WAN). The external device may include a PC or another image forming apparatus or the like.

The CPU301is connected with the opening and closing sensor305to detect whether or not the front door140is closed.

A sensor group306, including sensors153,155,173, and175, shown inFIG. 1, is disposed along the feeding path, by which the CPU301detects the presence, absence, and passing of the recording material102.

In addition, the CPU301is connected with the operating portion180. The CPU301receives the instructions of switching of the display content on the display screen and other operations, given by the operator at the selection keys of the operating portion180. The CPU301displays, on the display screen of the operating portion180, the status of operation of the image forming apparatus100, an operation mode selected by the selection key, and so on.

The CPU301is connected with a timer307. The timer307functions as a clock portion for measuring a time period. As will be described hereinafter, it counts the time for detection of a jammed sheet, and/or for a fixing element refreshing operation (fixing roller refreshing operation).

The CPU301is connected with a feeding portion308to control feeding of the recording material102. The feeding portion308includes a supply portion for feeding the recording material102from the recording material accommodating portion103to the feeding path, feeding rollers for feeding the recording material102on the feeding path, and flappers (flappers131,132,133, inFIG. 1) for the feeding paths.

In addition, the CPU301is connected with the image forming station309, which will be described hereinafter, to control the image forming station309.

The memory310of the fixing device includes the memory154of the first fixing device150mounted in the image forming apparatus100, and a memory174of the second fixing device170mounted to the image forming apparatus100. The CPU301is connected with the memories154,174of the first fixing device150and the second fixing device170mounted in the image forming apparatus100and writes in and reads out of the memories154,174.

The CPU301is connected with a main assembly memory312. The main assembly memory312is rewritable, non-volatile memory, and may be integral with the RAM302.

The CPU301is connected with a mechanism group X of the first fixing device150mounted in the image forming apparatus100to effect a temperature adjustment control and fixing element refreshing operation. The mechanism group X includes a temperature sensor320, a heater321, a moving mechanism322, a motor323, and a refreshing roller moving mechanism325.

The temperature sensor320includes a plurality of temperature sensors provided in the first fixing device150, including a thermister159(FIG. 3), and a thermister (unshown) for a pressing belt152.

The heater321includes a plurality of heaters provided in the first fixing device150, including a halogen heater161(FIG. 3), and a halogen heater (unshown) provided in a heating roller163.

The CPU301is connected with a mechanism group X of the second fixing device170mounted in the image forming apparatus100to effect temperature adjustment control and the fixing element refreshing operation. The mechanism group X for the second fixing device170is substantially the same as the mechanism group X of the first fixing device150, and therefore, the detailed description thereof is omitted by applying the same reference numerals to the corresponding elements. (In the description of the mechanism group X for the first fixing device150, the first fixing device150, the pressing belt152, and the heating roller163correspond to the second fixing device170, the pressing roller172, and the pressing roller172, respectively).

In this embodiment, the mechanisms are controlled by the CPU301. Alternatively, however, CPU circuit portions can be used for controlling the respective mechanisms, along with a main CPU circuit portion connected with the respective CPU circuit portions to effect the overall control.

The image forming apparatus100comprises stations120,121,122and123as the image forming station309(FIG. 2), an intermediary transfer belt115as an intermediary transfer member, and a transfer roller116as a transfer portion.

The stations120,121,122,123form yellow, magenta, cyan and black toner images, respectively, and transfer the toner images onto the intermediary transfer belt115.

The structure of the station120will be described. A photosensitive drum110as the image bearing member is rotatable in the counterclockwise the direction inFIG. 1. A primary charger111as a charge portion uniformly charges the surface of the photosensitive drum110. A laser unit112as an exposing portion includes a light source113for producing a laser beam to form an electrostatic latent image on the photosensitive drum110in accordance with an original image. A developing device114as a developing portion develops the electrostatic latent image formed on the photosensitive drum110, using toner, into a toner image. The structures of the stations121,122,123are the same as that of the station120, and therefore, the description is omitted for the sake of simplicity.

The toner images formed by the stations120,121,122,123are transferred onto the intermediary transfer belt115. The transfer roller116transfers the toner images superimposed on the intermediary transfer belt115onto the recording material102fed from the recording material accommodating portion103.

The first fixing device150and the second fixing device170, as the fixing portions, fix the toner image transferred onto the recording material102by applying heat and pressure to the recording material102.

The second fixing device170is disposed downstream of the first fixing device150with respect to the feeding direction of the recording material102. The second fixing device170functions to provide the toner image fixed on the recording material102by the first fixing device150with glossiness and/or to supplement the heat quantity for a large basis weight recording material (thick sheet, for example) which requires a large amount of heat for the fixing operation.

On the other hand, in the case that the heat by the first fixing device150is enough to fix the image, it is unnecessary to use the second fixing device170, and therefore, the recording material102is fed into the feeding path130bypassing the second fixing device170, for the purpose of saving the energy consumption. For example, this occurs in the case that the recording material102is plain paper or thin sheet, and high glossiness is not desired. As to whether to feed the recording material102into the second fixing device170or to feed the recording material102so as to bypass the second fixing device170(bypass route), the CPU301controls such an operation by switching the flapper131.

(4.2. Structure of Fixing Device)

The first fixing device150and the second fixing device170are detachably mountable to the first mounting portion141and the second mounting portion142(collectively, the mounting portion) of the image forming apparatus100, respectively. The first fixing device150and a second fixing device170can be replaced with other fixing devices having the following structures, respectively.

The first fixing device150is provided with a memory154as a storing portion. The second fixing device170is provided with a memory174as a storing portion. The details will be described hereinafter.

The first fixing device150is provided with sensors153and155as a jam detecting portion, and the second fixing device170is provided with sensors173,175as a jam detecting portion. The details will be described hereinafter. For the respective fixing devices, the upstream sensors155,175with respect to the feeding direction of the recording material102functions also as detecting portions for detecting the feeding of the recording material102to the respective fixing devices. The details will be described hereinafter.

FIG. 3is a sectional view of an example of a fixing portion. Referring toFIG. 3, the first fixing device150will be described in detail.

The first fixing device150comprises a fixing roller151(fixing member, rotatable member) and a pressing belt152(pressing member, rotatable member), which are cooperative with each other to form a nip for fixing the toner image on the recording material102.

The fixing roller151is a hollow roller containing therein a halogen heater161as a heating source. The thermister159as a temperature detecting portion is a sensor for sensing a temperature of the fixing roller151. The halogen heater161is controlled by the CPU301to be ON or OFF on the basis of the information of the temperature detected by the thermister159. This is done to adjust and maintain the temperature of the fixing roller151at a predetermined temperature. The predetermined temperature includes a tolerance.

The pressing belt152is an endless belt stretched around three rollers. To the inner surface of the pressing belt152, a pressing pad164is contacted to urge the pressing belt152toward the fixing roller151. The heating roller163, which is one of the three rollers around which the pressing belt152is stretched, is a hollow roller, and contains therein a halogen heater (unshown) as the heating source. Similarly to the fixing roller151, for the pressing belt152, the CPU301controls the halogen heater (unshown) in the heating roller163on the basis of detected temperature information by the thermister (unshown) for sensing the temperature. As a result, the temperature of the pressing belt152is maintained at a predetermined temperature.

The fixing roller151is rotated by a motor323(FIG. 2) as a driving source to feed the recording material102in the direction indicated by an arrow A inFIG. 3. The pressing belt152is rotated by the fixing roller151.

The first fixing device150is provided with a moving mechanism322(FIG. 2) for moving the pressing belt152to provide a contact state, in which the fixing roller151and the pressing belt152contact with each other to form the nip, and a spaced state in which they are spaced from each other. In this embodiment, the moving mechanism322moves the pressing belt152, but the fixing roller151may be moved instead of the pressing belt152, or both the fixing roller151and the pressing belt152may be moved.

On the other hand, the second fixing device170includes a pressing roller172, instead of a pressing belt, as the pressing member, and the fixing roller171(fixing member) and the pressing roller172(pressing member) form a nip for fixing the toner image on the recording material102. The pressing roller172is a hollow roller, and contains therein a halogen heater (unshown) as a heating source. The pressing roller172is provided with a thermister (unshown) as a temperature sensor. The CPU301controls the thermister and the halogen heater (unshown), so that the temperature of the pressing roller172is maintained at a predetermined temperature.

The above-described structures of the second fixing device170are similar to those of the first fixing device150, and therefore, the description of the structures of the second fixing device170will be omitted for the sake of simplicity.

In the following description, the first fixing device150will be taken, and the description also applies to the second fixing device170unless otherwise stated (i.e., the structures of the first fixing device150apply to the structures of the second fixing device170).

In this embodiment, the structures of the pressing sides of the first fixing device150and the second fixing device170are different from each other, but they may be the same. More particularly, the pressing side structures of the first fixing device150and the second fixing device170may use pressing belts or pressing rollers. Alternatively, the pressing side may comprise the pressing roller in the first fixing device150, and the pressing side may comprise a pressing belt in the second fixing device170.

The description will be made as to a refreshing roller156as a rubbing rotatable member for effecting a rubbing treatment for the surface of the rotatable member. The description will be made taking the rubbing treatment surface of the fixing roller151of the first fixing device150. The following description is applied also to the second fixing device170.

In this embodiment, the refreshing roller156effects the rubbing treatment of the surface of the fixing roller151. The refreshing roller156is capable of moving to contact or to be spaced from the fixing roller151, and is capable of rubbing the peripheral surface of the fixing roller151. The refreshing roller156comprises abrasive grain fixed on the peripheral surface thereof, and is rotated at a peripheral speed which is different from that of the fixing roller151, so that the peripheral surface of the fixing roller151is roughened (roughening roller).

More particularly, the refreshing roller156comprises a stainless steel pipe (SUS304) (base material) having an outer diameter of 12 mm, and a rubbing layer on the peripheral surface with a bonding layer therebetween, the rubbing layer including the abrasive grain bonded at a high density.

The rubbing layer can be provided by bonding various commercially available abrasive grain or a mixture thereof on the bonding layer. The examples of the material of the commercially available abrasive grain includes aluminum oxide, aluminum hydroxide oxide, silicon oxide, cerium oxide, titanium oxide, zirconia, lithium silicate, silicon nitride, silicon carbide, iron oxide, chromium oxide, antimony oxide, diamond or the like.

In this embodiment, the abrasive grain of the rubbing layer is abrasive grain of aluminum oxide (alumina abrasive grain, Alundum, Molundum). The abrasive grain of aluminum oxide is most widely used, and has sufficient hardness as compared with the fixing roller151, and in addition, the particles have acute angles, and therefore, the abrasive grain of aluminum oxide is preferable for the rubbing layer. In order that the rubbing treatment of the refreshing roller156performs the sufficient fixing element refreshing operation to provide the surface roughness of the fixing roller151, the particle size of the abrasive grain of the rubbing layer is preferably not less than 5 μm and not more than 20 μm, as a result of the experiments which will be described hereinafter.

The refreshing roller156is movable between a contact state position, in which it contacts the fixing roller151, and a spaced state position, in which it is spaced from the fixing roller151, by a refreshing roller moving mechanism325. The CPU301controls the refreshing roller moving mechanism325to control the state (contacting-spacing) of the refreshing roller156.

The refreshing roller156is driven by a motor324as a driving source with a peripheral speed difference relative to the fixing roller151. The CPU301controls the motor324for the refreshing roller156to control rotating and stopping of the refreshing roller156. The peripheral speed difference of the refreshing roller156may be provided by moving the peripheral surface thereof in the same or opposite peripheral moving direction relative to the surface of the fixing roller151.

The refreshing roller156is rotated by the motor324while being in contact with the fixing roller151by the refreshing roller moving mechanism325to rub the peripheral surface of the fixing roller151. The CPU301controls the refreshing roller moving mechanism325and the motor324for the refreshing roller156to cause the refreshing roller156to rub the fixing roller151to provide an even surface state of the peripheral surface of the fixing roller151.

(5. Glossiness Unevenness at the Widthwise End Portion of the Recording Material)

The preferability of the fixing element refreshing operation will be described.

The fixing roller151comprises a base layer of aluminum having an outer diameter of 68 mm, and an elastic layer of silicone rubber thereon having a rubber hardness of 20° (JIS-A under 1 kg load) and having a thickness of approx. 1.0 mm. The surface of the elastic layer is coated with a parting layer of fluorine resin tube having a thickness of 30 μm.

In the image forming operation of the image forming apparatus100, the first fixing device150forms a nip between the fixing roller151and the pressing belt152.

In the case that the toner having a high melting property is used in the oil-less fixing type device, as in this embodiment, the surface state of the fixing roller151tends to be reflected on the surface of the toner layer. In other words, fine pits and projections of the surface of the fixing roller151tend to appear on the surface of the output image. Such a property is called a reflection property. When the reflection property becomes high as a result of enhancement of the melting property of the toner, it is important to maintain the surface state of the fixing roller151from the standpoint of forming an image of the high image quality with high glossiness.

The fixing roller151in the initial state has a uniform specular-surface state over the entirety of the peripheral surface. At this time, the surface roughness of (ten point average roughness) Rz of the peripheral surface is about 0.1 μm-0.3 μm. The surface roughness Rz is a ten point average roughness (JIS) measured using a surface roughness measuring device SE-3400 available from Kabushiki Kaisha KOSAKA Kenkyusho, Japan. As the measuring condition, the feeding speed is 0.5 mm/sec, the cut-off level is 0.8 mm, and measurement length is 2.5 mm.

FIG. 4illustrates a state in which the fixing portion nips and feeds a recording material.

When the fixing process operation of the first fixing device150on the recording material102is repeated, the surface state of the fixing roller151gradually changes due to the contact with the end portions of the recording material102, paper dust, offset toner, or the like, and therefore, the surface of the fixing roller151is gradually roughened. By the recording materials102passing the same position with respect to the direction of the rotational axis of the fixing roller151, the degrees of the roughness of the fixing roller151are different between (I) a non-passing portion, (II) a passing portion, and (III) a boundary area there between.

The end portion of the recording material102is the end portion with respect to a direction perpendicular to the feeding direction of the recording material102, and is called edge portion.

FIG. 5illustrates glossiness unevenness at the edge of the recording material102. In the enlarged view ofFIG. 5(in which the damage on the fixing roller151is shown), the left side portion (white portion) is the (I) non-passing portion, the central portion (coarse dot portion) is the (III) boundary area, and the right side portion (gray portion) is the (II) passing portion.

The (I) non-passing portion is the area in which no sheet passes, and therefore, is not contacted by the recording material102. In the (I) non-passing portion, the surface of the fixing roller151contacts only the surface of the pressing belt152.

In the (II) passing portion, the recording material102passes, and therefore, contacts the fixing roller151. In the (II) passing portion, the surface of the fixing roller151is gradually roughened by the contact with fibers and loading material of the recording material102, and by externally added material of the developer on the recording material102. The (III) boundary area between the (II) passing portion and the (I) non-passing portion is repeatedly contacted by the edge portion of the recording material102, and therefore, the surface roughness of the fixing roller151in the (III) boundary area is higher than that in the (II) passing portion.

That is, the surface roughnesses of the fixing roller151are,

In the process of fixing the toner image on the recording material102, the fine surface shape of the fixing roller151is transferred onto the surface of the fixed image.

As shown inFIG. 5, if the surface states of the fixing roller151are different between the (II) passing portion and the (III) boundary area, the surface state of the fixed image is not even, and therefore, the fixed image exhibits a glossiness unevenness. In the portion ofFIG. 5showing the glossiness unevenness on the image (on the recording material), the left side portion (dot portion) is the portion corresponding to the (I) non-passing portion, the central portion (white portion) is the portion corresponding to the (III) boundary area, and the right side portion (grey portion) is the portion corresponding to the (II) passing portion. The width of the (III) boundary area is as small as approx. 1-2 mm, and the glossiness difference between the (I) non-passing portion and the (II) passing portion is remarkable because the glossiness unevenness is in the wide range.

The glossiness unevenness of the fixed image is dependent also on the kind of paper of the recording material102. For example, the glossiness unevenness which is not visible on the plain paper is remarkable on the gloss coated paper sheet having a high glossiness with which a high image quality is required because of the high smoothness of the surface. In the fixed image on the gloss coated paper sheet, a low glossiness stripe is remarkable at the position corresponding to the (III) boundary area (rougher than the other area) of the fixing roller151, and the glossiness difference between the (I) non-passing portion and the (II) passing portion. Therefore, the glossiness unevenness on the fixed image is remarkable as a whole.

As a result of the difference in the roughness of the surface of the fixing roller151between the (I) non-passing portion and the (II) passing portion, as described above, the difference in the glossiness on the fixed image occurs. Particularly, the (III) boundary area tends to be roughened and provides the glossiness difference relative to the (I) non-passing portion and the (II) passing portion.

In the foregoing, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170, and therefore, the description is omitted for the second fixing device170.

As described in the foregoing, when the recording materials102pass through the nip repeatedly, the unevenness of the surface state is produced in the longitudinal direction of the fixing roller151(the direction of the rotational axis).

In view of this, in the image forming apparatus100, after a predetermined number of recording materials102are fed into the first fixing device150, the fixing element refreshing operation for improving the surface state of the fixing roller151is carried out. In the following, the description will be made taking the first fixing device150as an example, and the same applies to the second fixing device170, and therefore, the description about the second fixing device will be omitted in this respect.

The refreshing roller156rubs the fixing roller151in the fixing element refreshing operation. By this, the surface roughness of the fixing roller151is made uniform in the longitudinal direction, thus improving the surface state of the fixing roller151.

The refreshing roller156provides the portion of the surface of the fixing roller151roughened by the passing of the recording materials102and the portion of the surface relatively less roughened with a great number of fine scores, to a predetermined level. That is, the refreshing roller156decreases the difference in the surface state of the entirety of the fixing roller151.

By this operation, the low glossiness stripe on the image at the position corresponding to the edge portion ((III) boundary area) and the glossiness difference between the (I) non-passing portion and the (II) passing portion are reduced. Thus, the surface state of the fixing roller151can be improved. By providing the surface of the fixing roller151with the great number of fine scores by the refreshing roller156, the scores are difficult to see on the image. That is, by superimposing the fine scores on the portion of the fixing roller151roughened by the end portion of the recording material102, using the refreshing roller156, the damage on the fixing roller151produced by the end portion of the recording materials102does not visibly appear on the recording material102.

The intended function of the refreshing roller156is to provide the surface of the fixing roller151with the fine scores, not to scrape the surface of the fixing roller151. That is, the refreshing roller156provides the surface with the scores substantially without scraping the surface of the fixing roller151. The rubbing by the refreshing roller156does not abrade the surface of the fixing roller151, and is as if it imprints the surface into the initial state.

In this embodiment, the fixing element refreshing operation is executed on the basis of the number of the recording materials102fed into the first fixing device150. More particularly, the predetermined number of the recording materials is 500 in this embodiment, and the fixing element refreshing operation is executed upon the number of the recording materials102(feeding number) into the first fixing device150exceeding 500.

In this embodiment, the CPU301functioning as the counter counts the feeding number on the RAM302in response to the signal from a sensor155.

The sensor155as the detecting portion is provided on the first fixing device150at a position upstream of the nip of the first fixing device150with respect to the feeding direction. The sensor155functions to detect the feeding of the recording material102into the first fixing device150, and is an optical sensor, for example. The CPU301detects the feeding of the recording material102into the first fixing device150by receiving the signal outputted in response to the passage of the recording material102by the sensor155.

The CPU301increases the value (count) on the RAM302for each detection of the feeding of the recording material102into the first fixing device150, and manages the number of the recording materials102fed into the first fixing device150.

The CPU301executes the fixing element refreshing operation after the count exceeds a predetermined number (500, in this embodiment).

The count method for the number of the recording materials102fed into the first fixing device150is not limited to the described method.

For example, the number fed into the first fixing device150may be counted on the basis of the printing number instructed in the printing job received by the operating portion180. For example, when the instructed printing job is 30 sheets, the CPU301feeds the 30 sheets into the first fixing device150one by one. Simultaneously, the CPU301increases the count on the RAM302by30.

More specifically, the description will be made as to the fixing element refreshing operation which is executed after the predetermined number of the recording materials102are fed into the first fixing device150.

In the fixing element refreshing operation, the CPU301controls the motor324for the refreshing roller to rotate the refreshing roller156. At this time, the CPU301controls the refreshing roller moving mechanism325to contact the refreshing roller156to the fixing roller151. By this, the refreshing roller156rubs the surface of the fixing roller151.

After the CPU301executes the rubbing of the fixing roller151by the refreshing roller156for a predetermined time, the CPU301spaces the refreshing roller156from the fixing roller151.

The time period of the rubbing treatment by the refreshing roller156(30 sec in this embodiment) is counted by the timer307provided in the image forming apparatus100. The time counting may be accomplished by a clock provided in the image forming apparatus100counting the time on the basis of the clock time outputted by the CPU301.

After elapse of the predetermined time period, the CPU301spaces the refreshing roller156from the fixing roller151and stops the rotation of the refreshing roller156. By this, the fixing element refreshing operation is completed.

(7. Effects of the Fixing Element Refreshing Operation)

In the fixing element refreshing operation, the refreshing roller156provides the surface of the fixing roller151with the great number of scores (directional thin grooves) extending along the rotational moving direction of the fixing roller151such that the surface roughness of Rz (10 point average roughness) of the fixing roller151is not less than 0.5 μm and not more than 2.0 μm. The grooves (scores) have a width not more than 10 μm at a density not less than 10 per 100 μm in the rotational axis direction of the fixing roller151.

By the great number of fine scores thus provided on the entirety of the peripheral surface of the fixing roller151by the refreshing roller156, the difference in the surface state between the (I) non-passing portion, the (II) passing portion, and the (III) boundary area is reduced, and therefore, the unevenness of the surface state on the fixing roller151is less remarkable.

By this, the glossiness difference of the fixed image onto which the surface state of the fixing roller151is transferred decreases to such an extent that it is difficult to observe. In addition, the low glossiness stripe at the position corresponding to the (III) boundary area on the fixed image is substantially eliminated, and the glossiness unevenness between the (I) non-passing portion and the (II) passing portion on the fixed image is not remarkable.

More particularly, the surface roughness of Rz (10 point average roughness) of the image (toner portion on the recording material102) on the recording material102having been fixed by the fixing roller151thus rubbed is not more than approximately 0.5 μm, with which the gloss difference is not easily observed. Sparsely distributed scores are easily observed, but densely (at high frequency) distributed scores are not easily observed as the glossiness difference.

The rubbing time period of the refreshing roller156suitable for the refreshment of the surface state of the fixing roller151(30 sec in this embodiment) is preset (stored in the ROM303). Also, the predetermined number for the start of the fixing element refreshing operation (500 sheets in this embodiment) is preset (stored in the ROM303). The time period and/or the number is not limited to the above examples, and can be properly selected depending on the structures of the device by one skilled in the art.

The stand-by mode is a state in which the image forming apparatus100is in the state capable of starting of the image forming operation and waits for the printing instructions (printing job) by the operator. The operating portion180receives the printing job, including information regarding the kind of recording material102(surface property, basis weight, size or the like) on which the image is to be formed, the number of prints, and one-side printing/both side printing.

When the main switch101of the image forming apparatus100is actuated, the image forming apparatus100carries out preparing operations (start-up operations) for the preparation for the image forming operation, and in particular, preparation of the respective parts of the image forming apparatus100, such as the first fixing device150, the second fixing device170, and the image forming station309. In the case that no printing job to start is received, even after the image forming operation of the image forming apparatus100is enabled (that is, the start-up operations are completed), or that the execution of the printing job is completed, the image forming apparatus100shifts to the stand-by mode.

When the image forming apparatus100is enabled to start the image forming operation, the CPU301displays “printable” on the operating portion (notifying portion)180.

In this embodiment, in the stand-by mode, the temperature control for the first fixing device150and the second fixing device170(the fixing roller151and pressing belt152, for example) is continued so that the printing operation can be started as soon as the printing job is received.

If a printing operation is received during the start-up operation, the received printing job is executed without entering the stand-by mode.

If sheet jamming occurs during the execution of the printing job, for example, the image forming apparatus100stops the operation and interrupts the printing job. In such a case, the start-up operation is carried out to enable the image forming operation of the image forming apparatus100after the jammed sheet is cleared. When the job is resumed after the interruption, the apparatus does not enter the stand-by mode, and restarts the job immediately after the completion of the start-up operation.

The exchanging system of the fixing device will be described.

The image forming apparatus100is capable of printing on various kinds and sizes of the recording material102. In order to provide high quality prints, in the image forming apparatus100of this embodiment, the fixing device can be exchanged depending on the kinds of the recording material102or the preference of the operator.

For example, the fixing device used when the recording material102is an envelope and the fixing device used when another material are different from each other. When the recording material102is an envelope, the fixing device exclusively for the envelope is used. The envelope is easily creased by the pressure applied during the fixing process. Therefore, it is desirable to use a fixing device adjusted in the pressure between the fixing roller151and the pressing belt152(nip pressure) particularly for envelopes.

The same applies to the second fixing device170.

Thus, according to the image forming apparatus100of this embodiment, the operator can exchange the fixing device depending on the kinds of the recording materials102or preferences of the operator.

When the fixing device is exchanged, the operator opens the front door140to take the mounted fixing device out of the image forming apparatus100. Then, the operator mounts another fixing device into the image forming apparatus100, and closes the front door140. In this embodiment, the first fixing device150and the second fixing device170are exchangeable, respectively.

(10. Memory of the Fixing Device)

In this embodiment, the fixing device is exchangeable, and therefore, the first fixing device150is provided with a memory154as a storing portion, and the second fixing device170is provided with a memory174as a storing portion. The memories154,174are rewritable non-volatile memories (storing portions), typically an EEPROM, a flash memory, or the like. A memory is also provided on a fixing device (not the first fixing device150or the second fixing device170already mounted in the image forming apparatus100) kept outside of the image forming apparatus100.

Each fixing device of a group of fixing devices, including the first fixing device150and the second fixing device170, is provided with the memory in order to solve the problem described below. The problem arises when the first and/or second fixing device is taken out of an image forming apparatus300, and then the fixing device is remounted in the image forming apparatus300. The following description will be made taking the first fixing device150as an example, but the same applies to the second fixing device170.

More particularly, the following situation may occur. That is, the fixing device to be replaced is the first fixing device150.

For example, the first fixing device150carries out the fixing element refreshing operation after 500 recording materials102are processed. In the case that a fixing device A, which is not exclusively for envelopes, is mounted in the main assembly of the apparatus as the first fixing device150, a printing job is carried out on 450 sheets (on A4 size plain paper longitudinally fed, for example). Thereafter, the operator is required to print on envelopes, and then the operator removes the fixing device A from the image forming apparatus100to mount the fixing device B exclusively for envelopes. The operator carries out the printing job including 50 envelopes with the fixing device B mounted as the first fixing device150.

The CPU301counts the number of the recording materials102fed into the first fixing device150by the counter provided in the main assembly100A of the image forming apparatus100, and the fixing element refreshing operation is executed after the feeding number exceeds the predetermined number. Therefore, when the fixing device is switched from the fixing device A to the fixing device B, the CPU301discriminates that the feeding number to the first fixing device150exceeds 500 when 50 sheets are processed by the fixing device B, and carries out the fixing element refreshing operation only for the fixing device B. Then, the CPU301discriminates that the fixing element refreshing operation after the 500 sheets feeding has been completed.

Some days later, when the operator is going to print on the recording material102(plain paper, for example) other than the envelope, the operator changes the fixing device to remount the fixing device A. The operator then executes printing on 50 sheets of recording material (on A4 size plain paper longitudinally fed, for example).

The fixing device A has already processed 450 sheets in the previous operation, and therefore, the uneven surface state of the fixing roller arises with respect to the longitudinal direction after only 50 sheets are processed. If the next printing job is carried out (on A4 size plain paper longitudinally fed, for example), the glossiness unevenness occurs on the outputted image, and as a result, the image quality is significantly deteriorated.

In view of this, this embodiment employs the memory154on the first fixing device150. By this embodiment, the first fixing device150and the replacement fixing device are capable of storing the information relating to the number of the recording materials102having been processed thereby, as shown inFIG. 10, for example, and the CPU301causes the memory154to store the information of the feeding number.FIG. 10illustrates an example of information stored in a memory of a fixing device.

(10.2. Count on the Basis of the Information Stored in the Memory of the Fixing Device)

The CPU301, functioning as the counter, counts the feeding number of the recording materials102fed into the first fixing device150on the basis of the information of the memory154.

By the CPU301counting the feeding number on the basis of the information of the memory154, a proper fixing element refreshing operation can be carried out for the first fixing device150on the basis of the information indicative of the correct feeding number. Therefore, the deterioration of the image quality on the output recording material102can be suppressed.

The structure of this embodiment will be described in more detail.

Upon the operator remounting the first fixing device150, the CPU301acquires the number of information from the memory154.

When the first fixing device150is to be exchanged, the operator opens the front door140, and draws the first fixing device150out of the image forming apparatus100and then exchanges the fixing device. Then, the first fixing device150is moved in the opposite direction to set it in the image forming apparatus100, and the front door140is closed.

The CPU301detects that the front door140is closed, on the basis of the signal from the opening and closing sensor305. Upon the detection of the closure of the front door140, the CPU301accesses the memory154of the first fixing device150. By this, it is confirmed that the first fixing device150is mounted. If the CPU301is unable to access the memory154, the CPU301discriminates that the first fixing device150is not mounted. The method for discriminating whether or not the first fixing device150is mounted is not limited to that described above, and may be discriminated by electrical conduction or non-conduction state between the image forming apparatus100and the first fixing device150, for example.

If the fixing device is exchanged in the OFF-state of the main switch101, the opening and closing sensor305is unable to detect in the closure of the front door140. Therefore, the CPU301accesses the memory154of the first fixing device150in response to the actuation of the main switch101. By this, it is confirmed that the first fixing device150is mounted. If the CPU301is unable to access the memory154, the CPU301discriminates that the first fixing device150is not mounted.

If the information acquired from the memory154upon the remounting of the first fixing device150exceeds the predetermined number, the CPU301executes the fixing element refreshing operation. When the information acquired from the memory154does not exceed the predetermined number, the CPU301increases the count of the feeding number of the recording materials102fed into the first fixing device150and stores the feeding number in the RAM302, continuing from the feeding number stored in the memory154. For example, when the information acquired from the memory154indicates 30 sheets, the CPU301increases the count to 31, 32, 33, and so on, and stores the count in the RAM302. When the count stored in the RAM302exceeds the predetermined number, the CPU301executes the fixing element refreshing operation. In this embodiment, the feeding of the recording material102into the first fixing device150is detected by the sensor155. After executing the fixing element refreshing operation, the CPU301resets the count on the RAM302.

The count per one sheet may be weighted depending on the length of the recording material102measured in the feeding direction. That is, the count value incremented on the RAM302or stored in memory154as the reference for executing the fixing element refreshing operation may be any data that corresponds to the recording material feeding number into the first fixing device150. In this case, similarly to the information relating to the length of the recording material102in the main-scanning direction, the information of the length of the recording material102in the feeding direction is acquired from the content of the printing job received by the CPU301. The degree of the weighting is prestored in the ROM303and is acquired by the CPU301.

The method for counting the feeding number on the basis of the information of the memory154is not limited to that described above. For example, the CPU301may count the number of the recording materials102fed into the first fixing device150, by renewing and recording the information of the feeding number of the memory154of the first fixing device150for each feeding of the recording material102into the first fixing device150. The CPU301counts the information of the feeding number stored in the memory154. Also in this case, therefore, the CPU301, as the counter, counts the feeding number of the recording materials102fed into the first fixing device150on the basis of the information in the memory154.

The CPU301may count the feeding number plus the feeding number acquired from the memory154up to the predetermined number. More particularly, when the information acquired from the memory154is 30, the CPU301increments the count value by one on the RAM302for each feeding of the recording material102into the first fixing device150. Assuming that the predetermined number is 500, the CPU301discriminates exceeding of the predetermined number, when the count on the RAM302reaches 470.

The reference on which the fixing element refreshing operation is executed may not be the number of the sheets of the recording material102fed into the first fixing device150. For example, it may be a total of the lengths of the recording materials102in the feeding direction fed into the first fixing device150. In this case, the memory154stores the total length of the recording materials102fed into the first fixing device150. The CPU301adds the length of the recording material102in the feeding direction fed into the first fixing device150to the value acquired from the memory154. When the value exceeds the predetermined length, the CPU301executes the fixing element refreshing operation.

In addition, for example, the reference on which the fixing element refreshing operation is executed, the time period in which the fixing roller151is fixing the image may be counted and stored in the memory154. In this case, the reference on which the fixing element refreshing operation is executed is also the time period (4000 sec, for example). The time period in which the fixing roller151is in contact with the pressing belt152counted by the timer (clock)307is measured by the timer307.

More particularly, the CPU301sets the timer307at an initial value acquired from the memory154as the initial fixing period. The timer307counts the time period in which the fixing roller151is in contact with the pressing belt152, continuing from the set initial value. When the value of the timer307exceeds the predetermined time period, the CPU301executes the fixing element refreshing operation. Alternatively, the initial value of the timer307may be zero, in which the CPU301adds the time counted by the timer307to the time stored in the memory154, so that the total image fixing period of the fixing roller151is obtained.

Also when no information of the feeding number is stored in the memory154(zero), the CPU301deems the information of the feeding number stored.

The memory154may store information other than the feeding number information. For example, as the information indicative of the usage, the memory154may store the kind of the recording material processed by the first fixing device150, such as the envelope or the A4 size.

(10.3. Count for Each Width Size)

Furthermore, in this embodiment, the feeding number is stored for each widthwise size of the recording material102. The widthwise size measured in the direction perpendicular to the feeding direction of the recording material102is called the main scan direction length (or width size).FIG. 10shows an example in which the feeding numbers are stored for each 5 mm main scan direction length of the recording material102.

As described hereinbefore, the roughened area in the (III) boundary area is produced by the edge portions of the recording materials102repeatedly contacting the same position of the fixing roller151with respect to the direction of the rotational axis of the fixing roller151. That is, the roughened area is produced with the increase of the feeding number of the recording materials102.

By the fixing element refreshing operation, the surface state of the fixing roller151is uniformized in the entirety of the longitudinal range (i.e., in the (I) non-passing portion, the (II) passing portion, and the (III) boundary area). Therefore, the unevennesses of the surface state of the fixing roller151produced by the edge portions of the recording materials102having different main scan direction lengths are also eliminated.

Therefore, in this embodiment, the number of the recording materials102fed into the first fixing device150is stored for each 5 mm of the main scan direction length of the recording material102, in the memory154. When the feeding number for any one of the main scan direction lengths exceeds the predetermined number (500, in this example), the CPU301executes the fixing element refreshing operation. Thereafter, the feeding numbers for all of the main scan direction lengths are reset (zero). When the feeding number for any one of the main-scanning lengths exceeds the predetermined number, the CPU301executes the fixing element refreshing operation.

The information of the main scan direction length of the recording material102is acquired from the content of the printing job received by the CPU301. When the operating portion180receives the printing job from the operator, it also receives the size of the recording material102(A3, for example) on which the image is to be formed, as one of the contents of the printing job.

By this, the glossiness unevenness on the output images can be suppressed, and also, the frequency of the fixing element refreshing operations is made lower than when the fixing element refreshing operation is carried out irrespective of the main scan direction length of the recording material102.

In this embodiment, the CPU301counts and stores in the memory154the feeding number of the recording materials102fed into the first fixing device150for each main scan direction length (i.e., for each width). When the count of the recording material102for any one of the main scan direction lengths exceeds the predetermined value during the printing operation, the fixing element refreshing operation is carried out after completion of the printing job currently being executed, and then the apparatus shifts into the stand-by mode. That is, if the count at the time of the completion of the image forming operation exceeds the predetermined value, the fixing element refreshing operation is executed after the completion of the current printing job. In addition, the CPU301executes the fixing element refreshing operation and shifts the apparatus into the stand-by mode, if the count of the recording materials102for any one of the main scan direction lengths exceeds the predetermined value when the main switch is actuated, or when the front door140is closed.

The description will be made in conjunction with the flow charts ofFIGS. 6 and 7.

The operations of the flow charts are carried out by the CPU301functioning as the executing portion (recording portion) controlling the related mechanisms of the image forming apparatus100in accordance with the control program stored in the ROM303. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

(11.1. Sequence Upon Actuation of the Main Switch and Upon Closing the Front Door)

FIG. 6is a flow chart showing the operations from the actuation of a main switch to a stand-by mode.

With the actuation of the main switch101, the CPU301starts. The CPU301discriminates whether or not the first fixing device150is mounted in the image forming apparatus100(S101). If the result of the discrimination is affirmative, the CPU301becomes accessible to the memory154. If the result of the discrimination at the step (S101) is negative, the operation returns to the step S101. In such a case, the CPU301may display a message, prompting the insertion of the first fixing device150, on the operating portion180. If the first fixing device150is mounted in the image forming apparatus100, the operation proceeds to the step S102.

The CPU301carries out the refreshing sequence shown inFIG. 8for the first fixing device150. The details of the operation will be described hereinafter.

In step S103, the CPU301waits for the image forming apparatus100to become capable of carrying out the image forming operation. The CPU301carries out the preparing operation (starting-up operation) for the start of the image forming operation for various mechanisms, such as the first fixing device150and the image forming stations309, after the actuation of the main switch101. The temperature control for the fixing roller151is part of the preparing operation, for example.

When the image forming apparatus100becomes capable of carrying out the image forming operation after the completion of the starting-up operations (Yes, S103), the CPU301displays “printable” or the like on the operating portion180(S104). By this, the operator is notified of the fact that the image forming apparatus100has become capable of carrying out the image forming operation. The apparatus is shifted into the stand-by mode.

FIG. 7is a flow chart showing the operations from the state in which a front door140is open to the stand-by mode.

The opened and closed states of the front door140are detected by the CPU301on the basis of the signal from the opening and closing sensor305of the front door140. When the front door140is open, the CPU301waits for the closing of the front door140(S201). When the front door140is open, the CPU301may display information to prompt to close the front door140. When the CPU301detects the closing of the front door140(S201), the operation proceeds to step S202.

Steps S202-S205are the same as the steps S101-S104ofFIG. 6, and therefore, the description thereof is omitted. After step S205, the operation proceeds to the stand-by mode.

FIG. 8is a flow chart of a refreshing sequence. The flow chart ofFIG. 8shows steps S102, S203, and the details of the refreshing sequence which will be described hereinafter.

First, the CPU301reads out the data stored in the memory154of the first fixing device150mounted in the image forming apparatus100(S301). The memory154stores the information indicative of the feeding number for each 5 mm of the length in the widthwise direction (i.e., each of the main scan direction lengths) of the recording material as shown inFIG. 10, for example.

When the information of the feeding numbers for the respective main scan direction lengths stored in the memory154is less than the predetermined number (predetermined value, 500 in this example) for any of the feeding numbers (counts in the memory154) for all of the main scan direction lengths of the recording material, the CPU301proceeds to step S303(S302).

The CPU301sets, as the value of the counter, the value for each of the main scan direction lengths read out of the memory154on the RAM302for each main scan direction length (S303).

On the other hand, in step S302, the CPU301proceeds to S304if the feeding numbers (count) for any one of the feeding number for the main scan direction length of all of the feeding numbers for the main scan direction lengths exceeds the predetermined value (500 in this example).

In the step S304, the CPU301executes the above-described fixing element refreshing operation. By this, the surface of the fixing roller151is rubbed, so that the surface state is made even.

After the completion of the fixing element refreshing operation, the CPU301sets the counts for the respective main scan direction lengths to zero. That is, the value on the RAM302is reset (S305).

The CPU301(recording portion, writing portion) resets all of the feeding numbers for the main scan direction lengths to zero as the feeding number information stored in the memory154(S306). More particularly, the values on the RAM302set in the step S305are copied into the memory154in combination with the main scan direction length information. By this, the CPU301is capable of executing the fixing element refreshing operation when the feeding number for any of the main scan direction lengths exceeds the predetermined value (500 in this example) after the execution of the fixing element refreshing operation again. That is, by setting the feeding numbers for all the main scan direction lengths to zero in the memory154after the execution of the fixing element refreshing operation, the CPU301records in effect the information indicative of the actual execution of the fixing element refreshing operation, in the memory154. In this manner, the fixing element refreshing operation can be carried out repeatedly, for each exceeding of the feeding number for any one of the main scan direction lengths of the recording materials102. The information of the feeding number may be written in the memory154in step S306with the CPU301detecting the opening of the front door140on the basis of the signal from the opening and closing sensor305in the stand-by mode state. In addition, the information of the feeding number may be written in the memory154in step S306with the deactuation of the main switch101. This is because the exchange of the first fixing device150necessitates the opening of the front door140.

(11.3. Sequence for Recording Material Counting)

FIG. 9is a flow chart of counting of the recording materials. More particularly, it is a flow chart of printing job execution by the image forming apparatus100.

In the stand-by mode in which the image forming apparatus100is capable of carrying out the printing operation, the image forming apparatus100waits for the printing job from the operating portion180or an external PC or the like through the outside I/F portion304(S401). At this time, the image forming apparatus100displays a selection screen for selecting the kind of the recording material102on the operating portion180or on a display screen of the external PC, and receives the kind of the recording material102to be used for the printing by the operator as a content of the printing job.

When the printing job is received (Yes, S401), the CPU301controls the mechanisms such as the image forming stations120-123, the first fixing device150, the second fixing device170, or the like, of the image forming apparatus100, and starts the image forming process operation of the image forming apparatus100. In other words, the printing job is started (S402).

If the CPU (counter)301detects the feeding of the recording material102to the first fixing device150(S404, Yes) in the stage in which the printing job is not completed (in S403, No), the CPU301increments the count on the RAM302. The CPU301increments the count corresponding to the main scan direction length of the fed recording material102, of the counts on the RAM302. The information of the main scan direction length of the fed recording material102is acquired by the CPU301on the basis of the content of the printing job in step S401. The CPU301detects the feeding of the recording material102to the first fixing device150depending on the signal from the sensor155.

On the other hand, if the feeding of the recording material102to the first fixing device150is not detected in step S404, the CPU301does not increment the count, and proceeds to S406. This occurs, for example, in the case that after the detection of the passage of the recording material102, the passage of the next recording material102is not detected after elapse of a predetermined time, despite the non-completion of the printing job. The predetermined time period is counted by the timer307.

When no sheet jamming in the image forming apparatus100is detected (S406, No), the CPU301continues the operation for the printing job until the completion of the printing job, while repeating the operations of steps S404and S405.

When the CPU301detects the jamming in the image forming apparatus100(S406), the CPU301records the count on the RAM302for the main scan direction length in the memory154as the information of the feeding number (S407). The CPU301detects the jamming in the image forming apparatus100on the basis of the signals from the sensor group306. For example, in the case that upon elapse of a predetermined time from the detection of the recording material102by the sensor disposed in the upstream side with respect to the feeding direction of the recording material102, the sensor disposed in the downstream side does not detect the passage of the recording material102, the CPU301discriminates that the recording material102stagnates in the portion between the two sensors. The predetermined time is counted by the timer307. when the jamming occurs in the image forming apparatus100, the CPU301interrupts the printing job. At this time, the jammed recording material stagnating in the feeding path of the image forming apparatus100is cleared by the operator, and therefore, the front door140or the like is opened.

The CPU301waits for the front door140to close (S408). When the CPU301detects the closing of the front door140on the basis of the signal from the opening and closing sensor305(S408), the refreshing sequence is carried out (S409).

The refreshing sequence in step S409corresponds to the flow shown inFIG. 8. In the refreshing sequence, the memory154in the first fixing device150is read out as described in the foregoing step S301. The memory154is read out because there is a possibility that the first fixing device150is exchanged when the front door140is opened for the jam clearance.

In step S410, the CPU301waits for the image forming apparatus100to become capable of carrying out the image forming operation. The CPU301carries out the preparing operation (starting-up operations) for resuming the image forming operation for various mechanisms such as the first fixing device150, the image forming station309, and the like, of the image forming apparatus100after the clearance of the jammed recording material. The temperature control for the fixing roller151is one of them, for example.

When the image forming apparatus100becomes capable of resuming the image forming operation after the completion of the starting-up operations (Yes, S410), the CPU301displays “printable” or the like on the operating portion180(S411). By this, the operator is notified of the fact that the image forming apparatus100becomes capable of carrying out the image forming operation. Thereafter, the operation returns to S403, and the CPU301resumes the operations for the remaining printing job and continues up to the completion of the printing job.

When the printing job is completed (S403, Yes), the CPU301discriminates whether or not any one of the feeding numbers for all the main scan direction lengths on RAM302exceeds the predetermined value (500 in this example) (S412).

If the result of the discrimination is negative, that is, if the values of the feeding numbers for all of the main scan direction lengths stored in the RAM302are less than the predetermined value (500 in this example), the CPU301proceeds to step S415.

If the result of the discrimination is affirmative, that is, if the values of the feeding number for any one of the main scan direction lengths exceeds the predetermined value (500 in this example), the CPU301executes the fixing element refreshing operation (S413). After the completion of the fixing element refreshing operation, the CPU301resets the values for all of the main scan direction lengths on the RAM302to zero. That is, the values of the counter are reset (S414).

In step S415, the CPU301records the count of the RAM302in the memory154for each main scan direction length as the information of the feeding number. As the operation has proceeded through the flow of the S414, the feeding numbers for all the main scan direction lengths as the information of the feeding number become zero.

The CPU301displays “printable” on the operating portion180to notify of the operativity of the image forming apparatus100(S416). Then, the image forming apparatus100is shifted into the stand-by mode.

By storing the information of the feeding number in the memory154before entering the stand-by mode, a correct feeding number can be stored in the memory154even when the first fixing device150is removed from the image forming apparatus100during the stand-by mode.

The writing in the memory154in step S407may be effected only when the jamming occurs in first fixing device150and/or the second fixing device170in S406. It is expected for the front door140to be opened by the operator after the occurrence of the jamming, because the jamming occurs in the fixing portion. This is because in the case of the jamming in the fixing portion, the operator clears the recording material102stagnating in the first fixing device150and/or the second fixing device170. The liability that the first fixing device150is exchanged by the operator arises when the front door140is opened.

In such a case, the sensors153,155function as the jam detecting portion. Each of the sensors may be an optical sensor, for example. The CPU301receives the signals from the sensors153and/or155to detect the stagnation of the recording material102in the first fixing device150(jamming in the fixing portion). For example, in the case that after the elapse of the predetermined period after the passage of the recording material102by the sensor155disposed at an upstream side with respect to the feeding direction of the recording material102, and the downstream side sensor153does not detect the passage of the recording material102, the CPU301discriminates that the recording material102stagnates between the sensors155and153. The predetermined time is counted by the timer307.

In the fixing element refreshing operation in steps S304and S413, the duration of the rubbing treatment by the refreshing roller156may not be constant. That is, the CPU301carries out the rubbing treatment for a time period corresponding to an amount, beyond the predetermined count (500in this example), of the count of the feeding number for the main scan direction length.

For example, for the predetermined value in steps S412and S413, when the count is 500, the rubbing treatment duration is 30 sec, and when the count is 600, the rubbing treatment duration is 40 sec.

In this case, the duration of the rubbing treatment may be gradually or stepwisely increased with the increase of the exceeding amount of the count of the feeding number. The data (table, function, or the like) for providing the correspondence between the exceeding amount of the count relative to the predetermined value and the rubbing treatment duration is stored in the ROM303beforehand.

As described hereinbefore, the exchange of the first fixing device150by the operator necessitates the opening and closing of the front door140of the image forming apparatus100. When the front door140of the image forming apparatus100is opened by the operator, the first fixing device150may be exchanged. In addition, when the main switch101is off, the first fixing device150may have been exchanged. Therefore, upon the actuation of the main switch101of the image forming apparatus100and/or the closure of the front door140, the CPU301reads the information out of the memory154of the first fixing device150to acquire the information of the feeding number in the memory154. By this, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of the more accurate information of the feeding number, and therefore, the deterioration of the image quality of the image on the output recording material102can be suppressed.

In the description of the foregoing embodiment, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170.

In Embodiment 1, when the count of the feeding number for any one of the main-scan direction lengths exceeds the predetermined value during the printing operation, the CPU301carries out the fixing element refreshing operation after the completion of the printing job, and then the image forming apparatus100shifts to the stand-by mode.

In Embodiment 2, when the total count of the feeding numbers for the main-scan direction lengths exceeds the predetermined value, the CPU301executes the fixing element refreshing operation in the period of the printing job.

In Embodiment 1, the CPU301counts the feeding number for the main scan direction length on the RAM302, and stores the count in memory154.

In Embodiment 2, the CPU301counts the feeding number on the memory154of the first fixing device150. The CPU301renews and records the count of the feeding number in the memory154for each detection of the feeding of the recording material102into the first fixing device150on the basis of the signal from the sensor155, thus functioning as the counter.

The same applies to the second fixing device170.

In the description of this embodiment, the same reference numerals as in Embodiment 1 are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

In the following, the description will be made with respect to the first fixing device150. The same applies to the second fixing device170.

In the memory154, the number of the recording materials102fed into the first fixing device150is stored for each 5 mm of the main scan direction length of the recording material102. After the total of the feeding numbers for the respective main scan direction lengths exceeds the predetermined value (500 in this example), the fixing element refreshing operation is executed by the CPU301. Thereafter, the feeding numbers for all of the main scan direction lengths are reset (zero). When the total count exceeds the predetermined value (500 in this example), again, the CPU301executes the fixing element refreshing operation.

In place of counting the recording materials for each main scan direction length on the memory154, all the recording materials fed into the first fixing device150may be counted irrespective of the main scan direction length.

The fixing element refreshing operation in this embodiment (in the period of the execution of the printing job) may be carried out after the interruption of the printing job (that is, by expanding the interval between the adjacent recording materials102fed into the first fixing device150), or while printing is continuously carried out (that is, while executing the fixing process operation). However, the former is preferable. In such a case, the likelihood of the production of the disturbance of the toner image during the fixing process operation attributable to the vibration or the like caused by the contact of the refreshing roller156to the fixing roller151for the execution of the fixing element refreshing operation can be reduced.

Referring to flow charts ofFIGS. 6 and 7of Embodiment 1, and the flow charts ofFIGS. 11 and 12, the description will be made. The operations in each flow chart are carried out by the CPU301as the executing portion (recording portion, writing portion) controlling the operation of the various mechanisms of the image forming apparatus100on the basis of control programs stored in the ROM303. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

(12.1. Sequence Upon Actuation of the Main Switch and Upon Closing the Front Door)

The sequence upon actuation of the main switch101and upon closing the front door140will be described referring to the flowchart ofFIGS. 6 and 7.

In this embodiment, in the steps S102(FIG. 6) and S203(FIG. 7), the operation proceeds to the refreshing sequence ofFIG. 11.

As to the other structures, they are the same as those of Embodiment 1, and the description thereof are omitted for the sake of simplicity.

FIG. 8is a flow chart of a refreshing sequence. The flow chart ofFIG. 11shows the details of the step S102(FIG. 6), and the step S203(FIG. 7) and the refreshing sequence in step S608, which will be described hereinafter.

A step S501is the same as the step S301ofFIG. 8, and therefore, the description thereof is omitted.

In step S502, the CPU301sums the feeding numbers for all of the main scan direction lengths stored in the memory154, and discriminates whether or not the sum (total count) exceeds the predetermined value.

If the result of the discrimination is affirmative, that is, the total count exceeds the predetermined value (500 in this example), the CPU301proceeds to a step S503(S502).

The step S503is the same as the step S304ofFIG. 8, and therefore, the description thereof is omitted.

After the completion of the fixing element refreshing operation (S503), the CPU301sets the counts for all of the main scan direction lengths to zero on the memory154. That is, the value on the memory154is reset (S504).

On the other hand, if the discrimination in the step S502is negative, that is, the total count is not more than the predetermined value (500 in this example), the CPU301completes the refreshing sequence without executing the fixing element refreshing operation.

(12.3. Sequence for Recording Material Counting)

FIG. 12is a flow chart of counting of the recording materials. More particularly, it is a flow chart of printing job execution by the image forming apparatus100.

Steps S601and S602are the same as S401and S402(FIG. 9), and therefore, the description is omitted.

If the CPU301detects that the recording material102is fed to the first fixing device150(S604, Yes) before the printing job is finished (S603, No), the CPU301increments the count of the memory154. The CPU301increments the count for the main scan direction length of the fed recording material102of the counts stored in the memory154. The information of the main scan direction length of the fed recording material102is acquired by the CPU301on the basis of the content of the printing job in step S601. The CPU301detects the feeding of the recording material102to the first fixing device150depending on the signal from the sensor155.

On the other hand, if the feeding of the recording material102to the first fixing device150is not detected in step S404, the CPU301does not increment the count, and proceeds to S606. This occurs, for example, in the case that after the detection of the passage of the recording material102, the passage of the next recording material102is not detected after elapse of predetermined time, despite the non-completion of the printing job. The predetermined time period is counted by the timer307.

When the jamming occurs in the image forming apparatus100(S606, Yes), the CPU301interrupts the printing job. At this time, the jammed recording material stagnating in the feeding path of the image forming apparatus100is cleared by the operator, and therefore, the front door140or the like is opened.

The CPU301waits for the front door140to close (S607). When the CPU301detects the closing of the front door140on the basis of the signal from the opening and closing sensor305(S607), the refreshing sequence is carried out (S608).

The refreshing sequence in step S4608corresponds to the flow shown inFIG. 11. In the refreshing sequence, the memory154in the first fixing device150is read out as described in the foregoing (S501). The memory154is read out because there is a possibility that the first fixing device150is exchanged when the front door140is opened for the jam clearance.

The step S609is the same as the step S410, and therefore, the description thereof is omitted.

When the image forming apparatus100becomes capable of resuming the image forming operation after the completion of the starting-up operations (Yes, S609), the CPU301displays “printable” or the like on the operating portion180(S610). By this, the operator is notified of the fact that the image forming apparatus100becomes capable of carrying out the image forming operation (S610).

Thereafter, the operation returns to step S603, and the CPU301resumes the operations for the remaining printing job and continues up to the completion of the printing job.

If the CPU301does not detect occurrence of jamming in the image forming apparatus100(S606, No), the CPU301discriminates whether or not the total count of the feeding numbers for all of the main scan direction lengths in the memory154exceeds the predetermined value (500 in this example) (S611).

In step S611, if the total count exceeds the predetermined value (500 in this example), the CPU301proceeds to a step S603, and the printing operation is continued until the printing job is finished.

In step S611, if the total count exceeds the predetermined value (500 in this example), the above-described fixing element refreshing operation is carried out (S612).

When the fixing element refreshing operation is completed, the CPU301sets the values for all the main scan direction lengths to zero. That is, the counter values are reset (S613).

Thereafter, the operation returns to step S603, where the CPU301continues the printing job until the printing job is finished.

After the printing job is completed (S603, Yes), the CPU301shifts to the stand-by mode.

In this embodiment, the counts of the feeding numbers of the recording materials102are managed on the memory154, and the CPU301records the counts of the feeding numbers in the memory154for each feeding of the recording material102to the first fixing device150. By this, more accurate information of the feeding number can be stored in the memory154even when the first fixing device150is taken out of the image forming apparatus100.

As described hereinbefore, the exchange of the first fixing device150by the operator necessitates the opening and closing of the front door140of the image forming apparatus100. When the front door140of the image forming apparatus100is opened by the operator, the first fixing device150may be exchanged. In addition, when the main switch101is off, the first fixing device150may have been exchanged. Therefore, whenever the actuation of the main switch101of the image forming apparatus100and/or the closure of the front door140occurs, the CPU301reads the information out of the memory154of the first fixing device150to acquire the information of the feeding number in the memory154. The CPU301counts the feeding number on the basis of the count stored in the memory154. By this, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of more accurate information of the feeding number, and therefore, the deterioration of the image quality of the image on the output recording material102can be suppressed.

In the description of the foregoing embodiment, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170.

The image forming apparatus100may be set at a mode not executing the above-described fixing element refreshing operation, by the setting of the user. In such a case, the operating portion180is provided with a selector which displays for the selection between the mode in which the fixing element refreshing operation is executed and in the mode in which it is not executed. The user is capable of selecting one of the modes through the operating portion180. The information of the selected mode is stored in the main assembly memory312as the set information of the image forming apparatus100. The operation program to be executed when the fixing element refreshing operation non-executing mode is selected is stored in the ROM303. When such a mode is selected, the CPU301executes the program.

The fixing element refreshing operation is necessary in order to suppress the glossiness non-uniformity due to the difference in the surface roughness between the (I) non-passing portion, the (II) passing portion, and the (III) boundary area of the fixing roller151, as described hereinbefore. The difference in the surface roughness of the fixing roller151appears as the glossiness unevenness when the recording material102passes through the nip in contact with the (I) non-passing portion, the (II) passing portion, and the (III) boundary area of the fixing roller151. Therefore, the glossiness unevenness can be suppressed by using the different fixing device having the same structure, for the respective main scan direction length of the recording material102as the first fixing device150. In view of this, some user who is concerned with the glossiness property evenness prepares the fixing devices for respective main scan direction lengths of the recording materials102in order to avoid the deterioration of the print quality.

In such a case, that is, to avoid the glossiness unevenness caused by the edge portions of the recording materials102, it is desirable not to execute the fixing element refreshing operation to avoid the fine scores provided by the refreshing roller156, which influences the glossiness property of the image.

By making the modes (execution and non-execution of the fixing element refreshing operation) selectable by the user, the apparatus can meet wider needs of the users.

With respect to the Embodiments 1-3, the contact of the end portions of the recording materials102with the fixing roller151is taken as the cause of the difference in glossiness on the fixed image, but the causes are not limited to that. For example, a separation claw contacting the fixing roller151may be provided to prevent the recording material102from wrapping around the fixing roller151.

In such a case, with the cumulation of the fixing process, there is a likelihood that the contact damage may occur by the contact of the separation claw to the surface of the fixing roller151. In the case that a plurality of separation claws are provided at intervals in the longitudinal direction (axial direction) of the fixing roller151, the surface of the fixing roller151is roughened adjacent to the contact position with separation claw, with the result of unevenness of the surface state over the length of the fixing roller151. As a result, the glossiness difference may arise on the fixed image.

Even in such a case, the influence to the image quality by the contact damage can be reduced by providing the refreshing roller156and executing the fixing element refreshing operation.

In Embodiments 1-4, the refreshing roller156is provided for the fixing roller151, and the surface of the fixing member is rubbed, but a rubbing rotatable member may be provided for a surface of a pressing belt152and/or a pressing roller172to rub the surface of the pressing member.

In the exchangeable fixing device system, the user exchanges the fixing devices depending on the kind of the recording material102or the user's preference. In such a case, there is a possibility that a better quality print can be provided if the fixing device not selected by the operator is used. That is, there is a likelihood that the advantage of the exchanging system is not enjoyed. In this embodiment, the image forming apparatus100notifies the operator of the matching between the selected recording material102and the selected fixing device.

In the following, the description will be made referring to an Embodiment 1 (FIGS. 8 and 9). The other structures are the same as in Embodiment 1, and therefore, the detailed description thereof is omitted for simplicity. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

In the memory154, identifying information indicative of the kind and/or usage (for envelopes, for example) is stored as the identifying information of the first fixing device150. On the other hand, the main assembly memory312stores information (limitation information) indicative of the kinds of the recording material102to limit the kinds of the recording material to be processed by the fixing device, in combination (correlation) with the identifying information.

In step S301ofFIG. 8, the CPU301reads out the identifying information of the memory154of the first fixing device150together with reading the data stored in the memory154of the first fixing device150mounted to the image forming apparatus100. The CPU301determines the kinds of the recording material102to be limited for the first fixing device150, on the basis of the identifying information and the kinds of the recording material102stored in the main assembly memory312.

In step S401ofFIG. 9, when the CPU301receives the printing job from the operator, the CPU301makes non-selectable the kinds of the recording material102not suitable for the first fixing device150on the selection screen.

Thus, the printing operation using improper first fixing device150can be prevented, thus assuring high quality prints.

The information corresponding to the kinds of the recording material102to be limited may be stored in the memory154of the first fixing device150not that of the main assembly memory312. In such a case, the CPU301reads the kinds of the recording material102to be limited out of the memory154of the first fixing device150together with reading the data out of the memory154at step S301. On the basis of the kinds of the recording material102to be limited, the CPU301acquires the kinds of the recording material102to be limited by the first fixing device150.

In addition, this embodiment may be incorporated in Embodiment 2, although the description is made with respect to the case in which this embodiment is incorporated in Embodiment 1. The description as to the case in which this embodiment is incorporated in Embodiment 2 is omitted, because the foregoing description applies to such a case.

In Embodiments 1-6, the CPU301makes the memory154of the first fixing device150and the memory174of the second fixing device170store the information of the number of the recording materials102fed to the first fixing device150and the second fixing device170. The CPU301may store the same information also in the main assembly memory312in parallel with the writing of the information in the memory154and174.

In the foregoing description of Embodiments 1-7, the operating portion180is provided with a display screen and a selection key, but the display screen may be a touch panel which also functions as a selector.

In the foregoing embodiments, the image forming apparatus100comprises both of the first fixing device150and the second fixing device170(tandem fixing). However, the present invention is applicable to an image forming apparatus100comprising only one fixing device150.

In the Embodiments 1-9, the image forming apparatus100comprises the image forming stations (120-123) for forming yellow, magenta, cyan and black toner images (color image forming apparatus), but the present invention is applicable to a monochromatic image forming apparatus. For example, there is a monochromatic image forming station for forming the toner images in black only.

In the Embodiments 1-10, the image forming apparatus100comprises an intermediary transfer belt115as an intermediary transfer member (intermediary transfer type), but the present invention is applicable to a direct transfer type apparatus as follows.

In such a case, the image forming station309includes the image forming stations (120-123) and a transfer feeding belt functioning as a transfer portion. The image forming stations (120-123) can be contacted by the transfer feeding belt. The image forming apparatus100feeds the recording material102from a recording material accommodating portion103to the transfer feeding belt. The transfer feeding belt electrostatically attracts the recording material102and carries it to a position where the recording material102is facing the image forming station, and a transfer roller is provided in the inside of the belt. The transfer roller transfers the toner image formed on the image bearing member onto the recording material102carried on the transfer feeding belt. By this, the toner image (unfixed) is formed on the recording material102.

(13. General Arrangement of Image Forming Apparatus)

FIG. 13is a sectional view of an example of an image forming apparatus according to Embodiments 12-23.

In the description of this embodiment, the same reference numerals as in the foregoing embodiments are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity. That is, for the description of the image forming apparatus300, the image forming apparatus100of the foregoing embodiments should also read as the image forming apparatus300.

The front door140as an opening and closing portion is provided for the opening of the main assembly300A of the image forming apparatus300for mounting a fixing device (first fixing device150, second fixing device170) to a mounting portion (first mounting portion141, second mounting portion142).

The image forming apparatus100is provided with an opening and closing sensor (optical sensor)305(FIG. 14) as a sensor for sensing a closed state of the front door140. The front door140is provided with a projection (unshown), which is inserted into a receiving portion (unshown) of the main assembly300A of the image forming apparatus300by the closing of the front door140. The CPU301detects the closing of the front door140on the basis of a signal produced by the opening and closing sensor305upon the insertion of the projection into the receiving portion. On the other hand, when no output signal is produced by the opening and closing sensor305, the CPU301detects that the front door140is open. In an alternative structure, the CPU301detects the opening of the front door140on the basis of the signal produced by the opening and closing sensor305upon the opening of the front door140, and the CPU301that the front door140is closed when the signal from the sensor305is not produced.

(14. Structure of Control System)

FIG. 14is a block diagram of a control system according to Embodiments 12-23. In the description of this embodiment, the same reference numerals as in the foregoing embodiments are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

The image forming apparatus300(FIG. 13) is provided with a CPU301, a RAM302, and a ROM303for controlling the operation of the image forming apparatus100.

The CPU301, functioning as a controller, carries out a basic control of the image forming apparatus300by executing control programs stored in the ROM303. The CPU301uses the RAM302as a work area for executing the processing of the control program.

The CPU301is electrically connected with the RAM302and the ROM303, and various mechanisms to be controlled.

In addition, the CPU301functions also as a counter for counting the recording materials102fed into the first fixing device150or second fixing device170. The specific structure will be described hereinafter.

An external I/F portion304is a communication circuit for communication with an external device connected through a network (LAN and/or WAN). The external device may include a personal computer (PC) or another image forming apparatus or the like.

A storing device200is an example of an external device connected with the outside I/F portion304through the network. The details will be described with respect to Embodiment 14.

The CPU301is connected with the opening and closing sensor305to detect whether or not the front door140is closed.

A sensor group306, including sensors153,155,173, and175, shown inFIG. 13, is disposed along the feeding path, by which the CPU301detects the presence, absence, and passing of the recording material102.

The CPU301is connected with the operating portion180. The CPU301receives the instructions of switching of the display content on the display screen and other operations, given by the operator at the selection keys of the operating portion180. The CPU301displays, on the display screen of the operating portion180, the status of operation of the image forming apparatus300, an operation mode selected by the selection key, and so on.

In addition, the CPU301is connected with a timer307. The timer307function as a clock portion for measuring a time period. As will be described hereinafter, it counts the time for detection of a jammed sheet, and/or for a fixing element refreshing operation.

The CPU301is connected with a feeding portion308to control feeding of the recording material102. The feeding portion308includes a supply portion for feeding the recording material102from the recording material accommodating portion103to the feeding path, feeding rollers for feeding the recording material102on the feeding path and flappers for the feeding paths.

In addition, the CPU301is connected with the image forming station309, which will be described hereinafter, to control the image forming station309.

The CPU301is connected with a first resistance detecting portion1310, which will be described hereinafter, to identify the first fixing device150mounted in the image forming apparatus300. When the first fixing device150is mounted in the image forming apparatus300, the first resistance detecting portion1310is electrically connected with a resistor1154of the first fixing device150.

The CPU301is connected with a second resistance detecting portion1311to identify the second fixing device170mounted in the image forming apparatus300. When the second fixing device170is mounted in the image forming apparatus300, the second resistance detecting portion1311is electrically connectable with a resistor1174of the second fixing device170.

The CPU301is connected with a main assembly memory312. The main assembly memory312is rewritable non-volatile memory and may be integral with the RAM302.

The CPU301is connected with a mechanism group X of the first fixing device150mounted in the image forming apparatus100to effect a temperature adjustment control and fixing element refreshing operation. The mechanism group X includes a temperature sensor320, a heater321, a moving mechanism322, a motor323, and a refreshing roller moving mechanism325.

The temperature sensor320includes a plurality of temperature sensors provided in the first fixing device150, including a thermister159(FIG. 3), and a thermister (unshown) for the pressing belt152.

The heater321includes a plurality of heaters provided in the first fixing device150, including a halogen heater161(FIG. 3), and a halogen heater (unshown) provided in the heating roller163.

The CPU301is connected with a mechanism group X of the second fixing device170mounted in the image forming apparatus300to effect temperature adjustment control and the fixing element refreshing operation. The mechanism group X for the second fixing device170is substantially the same as the mechanism group X of the first fixing device150, and therefore, the detailed description thereof is omitted by applying the same reference numerals to the corresponding elements. (In the description of the mechanism group X for the first fixing device150, the first fixing device150, the pressing belt152, and the heating roller163correspond to the second fixing device170, the pressing roller172, and the pressing roller172, respectively).

In this embodiment, the mechanisms are controlled by the CPU301. Alternatively, however, the use can be made with CPU circuit portions for controlling the respective mechanisms, and a main CPU circuit portion connected with the respective CPU circuit portions to effect the overall control.

The image forming apparatus300comprises stations120,121,122and123as the image forming station309(FIG. 13), an intermediary transfer belt115as an intermediary transfer member, and a transfer roller116as a transfer portion. The image forming stations are the same as those of Embodiment 1, and therefore, in the description of this embodiment, the same reference numerals as in Embodiment 1 are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

The first fixing device150and the second fixing device170as the fixing portion fix the toner image transferred onto the recording material102by applying heat and pressure to the recording material102(FIG. 13).

The second fixing device170is disposed downstream of the first fixing device150with respect to the feeding direction of the recording material102. The second fixing device170functions to provide the toner image fixed on the recording material102by the first fixing device150with glossiness and/or to supplement the heat quantity for a large basis weight recording material (thick sheet, for example) which requires a large amount of heat for the fixing operation.

On the other hand, in the case that the heat by the first fixing device150is enough to fix the image, it is unnecessary to use the second fixing device170, and therefore, the recording material102is fed into the feeding path130bypassing the second fixing device170, for the purpose of reducing the energy consumption. For example, this occurs in the case that the recording material102is plain paper or thin sheet, and high glossiness is not desired. As to whether to feed the recording material102into the second fixing device170or to feed the recording material102bypassing the second fixing device170(bypass route), the CPU301controls such an operation by switching the flapper131.

(16.2. Structure of Fixing Device)

The first fixing device150and the second fixing device170are detachably mountable to the first mounting portion141and the second mounting portion142(collectively, the mounting portion) of the image forming apparatus300, respectively. The first fixing device150and a second fixing device170can be replaced with the fixing devices having the following structures, respectively.

The first fixing device150is provided with a resistor1154as a discrimination portion. The second fixing device170is provided with a resistor1174as a discrimination portion. The details will be described hereinafter.

The first fixing device150is provided with sensors153and155as a jam detecting portion, and the second fixing device170is provided with sensors173and175as a jam detecting portion. The details will be described hereinafter. For the respective fixing devices, the upstream sensors155,175with respect to the feeding direction of the recording material102functions also as detecting portions for detecting the feeding of the recording material102to the respective fixing devices. The details will be described hereinafter.

FIG. 3is a sectional view of an example of a fixing portion. In the description of this embodiment, the same reference numerals as in the foregoing embodiments are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

The following description will be made with respect to the first fixing device150, but the same applies to the second fixing device170unless otherwise described (i.e., the structures of the first fixing device150apply to the structures of the second fixing device170).

In this embodiment, the structures of the pressing sides of the first fixing device150and the second fixing device170are different, but they may be the same. More particularly, the pressing side structures of the first fixing device150and the second fixing device170may use pressing belts or pressing rollers. The pressing side of the first fixing device150may be a pressing roller, and the pressing side of the second fixing device170may be a pressing belt.

As to the refreshing roller156as the rubbing rotatable member for rubbing the surface of the rotatable member, the description with respect to Embodiment 1 applies, and therefore, the detailed description thereof is omitted for simplicity (see 4.3 Refreshing roller).

(17. Glossiness Unevenness at the Widthwise End Portion of the Recording Material)

The reason for the necessity of the fixing element refreshing operation has been described with respect to Embodiment 1, and therefore, the description thereof is omitted (see 5. Glossiness unevenness produced by end portions of the recording material).

As described in the foregoing, when the recording materials102pass through the nip repeatedly, the unevenness of the surface state is produced in the longitudinal direction of the fixing roller151(the direction of the rotational axis).

In view of this, in the image forming apparatus300, after a predetermined number of recording materials102are fed into the first fixing device150, the fixing element refreshing operation for improving the surface state of the fixing roller151is carried out. The fixing element refreshing operation is the same as that of Embodiment 1, and therefore, the description thereof is omitted (see 6. Fixing roller refreshing operation; 6. 1. Recording material counting method; 6. 2. Fixing roller refreshing operation).

(19. Effects of the Fixing Element Refreshing Operation)

As to the effects of the fixing element refreshing operation, the description in Embodiment 1 applies, and therefore, the description thereof is omitted for simplicity (see 7. Effects of fixing element refreshing operation).

The stand-by mode is a state in which the image forming apparatus300is in the state capable of starting of the image forming operation and waits for the printing instructions (printing job) by the operator. The operating portion180receives the printing job, including information regarding the kind of recording material102(surface property, basis weight, size or the like) on which the image is to be formed, the number of prints, and one-side printing/both side printing. The details thereof are the same as with Embodiment 1, and therefore, the description thereof is omitted (see 8. Stand-by mode) (the image forming apparatus100of the foregoing embodiments should read as the image forming apparatus300).

The fixing device is exchangeable system of this embodiment is the same as that of Embodiment 1, and therefore, the description thereof is omitted for simplicity (see 9. Fixing device exchanging system).

(22. Discrimination Portion of Fixing Device and Main Assembly Memory)

In this embodiment, the first fixing device150is provided with a resistor1154as a discrimination portion, and the second fixing device170is provided with a resistor1174as a discrimination portion.

The fixing device prepared outside the image forming apparatus300as a replacement fixing device is also provided with a resistor as a discrimination portion.

These resistors (provided on the first fixing device150, the second fixing device170, and the replacement fixing device) have resistances which are different from each other for identifying the respective developing devices, and function as discrimination portions.

In addition, the image forming apparatus300is provided with a main assembly memory312as a storing portion. The main assembly memory312is a rewritable non-volatile memory, a typical example of which is EEPROM, flash memory, or the like. However, it may be integral with RAM302if it is rewritable and non-volatile.

In the following, the description will be made as to the first fixing device150, but it applies to the second fixing device170.

(22.1. Discriminating Method for Fixing Device)

In the state that the first fixing device150is mounted in the image forming apparatus300, the CPU301detects the current flowing through the resistor1154when the regular voltage is applied to the resistor1154. More particularly, the image forming apparatus300is provided with an ammeter as a first resistance detecting portion1310, the ammeter being effective to detect the current flowing between the resistor1154and the voltage application portion at which the regular voltage is applied to the resistor1154. The CPU301monitors the output of the ammeter.

When the regular voltage is applied, the current corresponds to the resistance value one by one because of the Ohm's law. The CPU301acquires an output of the ammeter predetermined resistance of the resistor1154. The first fixing device150and the replacement fixing device have resistors having different resistance values, and therefore, the CPU301is capable of discriminating the fixing device depending on the difference of the output of the ammeter. Thus, the resistance value is the identifying information.

The discrimination of the first fixing device150on the basis of the resistance of the resistor1154by the CPU301is called “discrimination (acquirement) of ID of the first fixing device150(fixing device)” in the following description.

The structure of the second resistance detecting portion1311is the same as that of the first resistance detecting portion1310, and therefore, the description thereof is omitted. In addition, the same applies to the second fixing device170, and therefore, the description is omitted.

The CPU301may use the output of the ammeter as the identifying information without acquiring the resistance value of the resistor1154. That is, the CPU301may record the output of the ammeter in the main assembly memory312as in the ID of the fixing device.

In this embodiment, the discrimination portion includes a resistor, but the discrimination method is not limited to the above-described examples. For example, DIP switches are usable as the discrimination portion provided on the fixing device (first fixing device150, second fixing device170, and replacement fixing device). In such a case, the switches different depending on whether the individual fixing devices are in an ON state beforehand (the on-off state and position of the switches are different depending on the fixing devices). The CPU301is connected with the DIP switch of the fixing device mounted in the image forming apparatus300, and the switch in the ON state produces a signal to the CPU301in response to an input signal from the CPU301. The CPU301detects the signal from the ON state switch (acquires the fixing device ID) to discriminate the fixing device. For example, when the CPU301supplies signals to the first and second switches, and detects the output signal from the first switch, the CPU301discriminates it is the fixing device A, when the CPU301detects the output signal from the second switch, it is the fixing device B, and when the CPU301detects the signals from both of the first and second switches, it is the fixing device C.

As another method for discriminating the fixing device from the replacement fixing device, the discrimination portion on the fixing device (first fixing device150, second fixing device170, or replacement fixing device) may be a memory storing the discrimination name (identifying information) of the fixing device. In such a case, the memory is a rewritable non-volatile memory such as EEPROM, flash memory, or the like. The CPU301is connected with the memory of the fixing device mounted in the image forming apparatus300, and the CPU301discriminates the fixing device by reading the discrimination name of the fixing device stored in the memory (by acquiring the fixing device ID).

(22.2. Reason for the Provision of the Fixing Device Discrimination Portion)

The resistors (discrimination portions) are provided on the group of the fixing devices including the first fixing device150and the second fixing device170to provide a solution to the following problem. The problem arises when the first and/or second fixing device is once taken out of the apparatus300, and then the fixing device is remounted in the image forming apparatus300. The following description will be made taking the first fixing device150as an example, but the same applies to the second fixing device150. The following description is applied also to the second fixing device170.

More particularly, the following situation may occur. That is, the fixing device to be replaced is the first fixing device150.

For example, the first fixing device150carries out the fixing element refreshing operation after 500 recording materials102are processed (after the feeding number becomes 500). That is, the predetermined number is 500. In the case that the fixing device A, which is not exclusively for envelopes, is mounted in the main assembly of the apparatus as the first fixing device150, printing on 450 sheets of recording material102(on A4 size plain paper longitudinally fed, for example) is carried out. Thereafter, the operator is required to print on envelopes, and then the operator removes the fixing device A from the image forming apparatus300to mount the fixing device B exclusively for envelopes. The operator carries out the printing job including 50 envelopes with the fixing device B mounted as the first fixing device150.

The CPU301counts the feeding number of the recording materials102into the first fixing device150by the counter provided in the main assembly300A of the image forming apparatus300, and the fixing element refreshing operation is executed after the feeding number exceeds the predetermined number. That is, the CPU301executes the fixing element refreshing operation after the feeding number exceeds in the predetermined number, irrespective of whether the fixing device mounted as the first fixing device150is the fixing device A or the fixing device B. Therefore, when the fixing device150is switched from the fixing device A to the fixing device B, the CPU301discriminates that the feeding number to the first fixing device exceeds 500 when the 50 sheets are processed by the fixing device B, and carries out the fixing element refreshing operation for the fixing device B only. Then, the CPU301discriminates that the fixing element refreshing operation after feeding of 500 sheets has been completed.

Some days later, when the operator is going to print on the recording material102(plain paper, for example) other than the envelope, the operator changes the fixing device150by remounting the fixing device A. The operator then executes a printing job of 50 sheets (on A4 size plain paper longitudinally fed, for example).

The fixing device A has already processed 450 sheets in the previous operation, and therefore, the uneven surface state of the fixing roller arises with respect to the longitudinal direction upon only 50 sheets being processed. If the next printing job is carried out (on A4 size plain paper longitudinally fed, for example), the glossiness unevenness occurs on the outputted image, that is, the image quality is significantly deteriorated.

In view of this, the resistor1154is provided on the first fixing device150in this embodiment. In the above-described situation, for example, the fixing device A is provided with a resistor having a resistance R1, and the fixing device B is provided with a resistor having a resistance R2which is different from R1.

The CPU301stores the information indicative of the number of the recording materials102fed to the first fixing device150in correlation with the ID (fixing device identifying information) of the fixing device in the main assembly memory312.FIG. 19illustrates an example of information stored in the main assembly memory312.

(22.3. Count on the Basis of the Information Stored in the Main Assembly Memory)

The CPU301, as the counter, counts of the feeding number of the recording materials102fed to the first fixing device150in correlation with the information corresponding to the ID of the first fixing device150stored in the main assembly memory312.

By doing so, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of the more accurate feeding number. Therefore, the deterioration of the image quality on the output recording material102can be suppressed.

The structure of this embodiment will be described in more detail.

Upon the operator remounting the first fixing device150, the CPU301acquires the ID of the fixing device from the first fixing device150. The mounting of the first fixing device150will be described hereinafter. The CPU301acquires, from the main assembly memory312, the information of the feeding number corresponding to the ID of the fixing device acquired from the first fixing device150.

If the information acquired from the main assembly memory312exceeds the predetermined number, the CPU301executes the refresh operation. If not, the CPU301increases the count of the feeding number of the recording materials102to the first fixing device150, continuing from the feeding number stored in the main assembly memory312, on the RAM302. For example, when the information acquired from the main assembly memory312is 30, the CPU301increases the count to 31, 32, 33, and so on, for each feeding of the recording material102to the first fixing device150, and stores the count in the RAM302. When the count on the RAM302exceeds the predetermined number, the CPU301executes the fixing element refreshing operation. In this embodiment, the feeding of the recording material102into the first fixing device150is detected by the sensor155. After executing the fixing element refreshing operation, the CPU301resets the count on the RAM302.

The count per one sheet may be weighted depending on the length of the recording material102measured in the feeding direction. That is, the count value incremented on the RAM302or stored in the main assembly memory312as the reference for executing the fixing element refreshing operation may be any data that corresponds to the recording material feeding number into the first fixing device150. In this case, similarly to the information relating to the length of the recording material102in the main-scanning direction, the information of the length of the recording material102in the feeding direction is acquired from the content of the printing job received by the CPU301. The degree of the weighting is prestored in the ROM303and is acquired by the CPU301.

The method for counting the feeding number on the basis of the information of the main assembly memory312is not limited to that described above. For example, the CPU301may count the number of the recording materials102fed into the first fixing device150, by renewing and recording the information of the feeding number of the main assembly memory312of the first fixing device150for each feeding of the recording material102into the first fixing device150. Here, the information of the feeding number in the main assembly memory312renewed by the CPU301is correlated with the ID of the first fixing device150mounted in the image forming apparatus300. The CPU301counts the information of the feeding number stored in the main assembly memory312. Also in this case, therefore, the CPU301, as the counter, counts the feeding number of the recording materials102into the first fixing device150on the basis of the information in the main assembly memory312correlated with the ID of the first fixing device150mounted in the main assembly300A.

The CPU301may count the feeding number plus the feeding number acquired from the main assembly memory312up to the predetermined number. More particularly, when the information acquired from the main assembly memory312is 30, the CPU301increments the count by one on the RAM302for each feeding of the recording material102into the first fixing device150. Assuming that the predetermined number is 500, the CPU301discriminates exceeding of the predetermined number, when the count on the RAM302reaches 470.

The reference on which the fixing element refreshing operation is executed may not be the number of the sheets of the recording material102fed into the first fixing device150. For example, it may be a total of the lengths of the recording materials102in the feeding direction fed into the first fixing device150. In this case, the main assembly memory312stores the total length of the recording materials102fed into the first fixing device150in correlation with the ID of the first fixing device150. The CPU301adds the length of the recording material102in the feeding direction fed into the first fixing device150to the value acquired from the main assembly memory312. When the value exceeds the predetermined length, the CPU301executes the fixing element refreshing operation.

In addition, for example, as the reference on which the fixing element refreshing operation is executed, the time period in which the fixing roller151is fixing the image may be counted and stored in the main assembly memory312in correlation with the ID of the first fixing device150. In this case, the reference on which the fixing element refreshing operation is executed is also time period (4000 sec, for example). The time period in which the fixing roller151is in contact with the pressing belt152is counted by the timer (clock)307. More particularly, the CPU301sets the timer307at an initial value acquired from the main assembly memory312as the initial fixing period. The timer307counts the time period in which the fixing roller151is in contact with the pressing belt152, continuing from the set initial value. When the value of the timer307exceeds the predetermined time period, the CPU301executes the fixing element refreshing operation. Alternatively, the initial value of the timer307may be zero, in which the CPU301adds the time counted by the timer307to the time stored in the main assembly memory312, so that the total image fixing period of the fixing roller151is obtained.

Also when no information of the feeding number is stored in the main assembly memory312(zero), the CPU301deems the information of the feeding number stored.

The main assembly memory312may store the information other than the feeding number information. For example, the information indicative of the usage of a kind of the recording material processed by the first fixing device150, such as an envelope or an A4 size sheet, may be stored. In addition, in the case that the fixing device mountable to the first mounting portion141and the fixing device mountable to the second mounting portion142are different from each other, the information indicative of whether the fixing device is mountable to the first mounting portion141or to the second mounting portion142may be stored.

Furthermore, the main assembly memory312may store the information for a plurality of fixing devices.

(22.4. Mounting of Fixing Device)

The mounting of the first fixing device150will be described.

When the first fixing device150is to be exchanged, the operator opens the front door140, and draws the first fixing device150out of the image forming apparatus300. Then, the first fixing device150is moved in the opposite direction to set it in the image forming apparatus300, and the front door140is closed.

The CPU301detects that the front door140is closed, on the basis of the signal from the opening and closing sensor305. The CPU301confirms the electrical conduction state between the image forming apparatus300and the first fixing device150, with the detection of the closure of the front door140, by which the mounting of the first fixing device150in the image forming apparatus300is confirmed.

If the fixing device is exchanged in the OFF-state of the main switch101, the opening and closing sensor305is unable to detect in the closure of the front door. Therefore, the CPU301confirms the electric conduction state between the image forming apparatus300and the first fixing device150with the actuation of the main switch101, by which the mounting of the first fixing device150in the image forming apparatus300is confirmed.

More particularly, the image forming apparatus300is provided with an ammeter, and the CPU301monitors an output of the ammeter, so that it can detect that the electric current flows. When the first fixing device150is mounted in the image forming apparatus300, the ammeter and the first fixing device150are electrically connected with each other. By this, the ammeter is capable of detecting the current flowing to the first fixing device150when the first fixing device150is supplied with a predetermined voltage. If the ammeter detects the electric current upon the application of the predetermined voltages to the first fixing device150, it means that the image forming apparatus300and the first fixing device150are electrically connected with each other, and therefore, the CPU301discriminates that the first fixing device150is mounted. On the other hand, if the ammeter does not detect the electric current upon the application of the predetermined voltage to the first fixing device150, the first fixing device150is not electrically connected with the image forming apparatus300, and therefore, the CPU301discriminates that the first fixing device150is not mounted. The measurement of the current by the ammeter may also detect the resistance value of the resistor1154, which will be described hereinafter.

The method for discriminating whether or not the first fixing device150is mounted is not limited to the above-described method.

For example, the first fixing device150is provided with a signal output portion (memory and/or CPU, for example) for outputting a signal in response to an input signal from the CPU301. The CPU301supplies the signal to the signal output portion, upon the detection of the closure of the front door140. The CPU301may confirm the mounting of the first fixing device150by detecting the signal outputted in response to the input of the signal to the signal output portion. The CPU301discriminates that the first fixing device150is not mounted if the signal to be outputted upon the input of the signal to the signal output portion is not detected.

(22.5. Count for Each Width Size)

Furthermore, in this embodiment, the feeding number is stored for each widthwise size of the recording material102.FIG. 19shows an example in which the feeding numbers are stored for each 5 mm main scan direction length of the recording material102. The widthwise size measured in the direction perpendicular to the feeding direction of the recording material102is called the main scan direction length (or width size).

As described hereinbefore, the roughened area in the (III) boundary area is produced by the edge portions of the recording materials102repeatedly contacting the same position of the fixing roller151with respect to the direction of the rotational axis of the fixing roller151. That is, the roughened area is produced with the increase of the feeding number of the recording materials102.

By the fixing element refreshing operation, the surface state of the fixing roller151is uniformized in the entirety of the longitudinal range (i.e., the (I) non-passing portion, the (II) passing portion, and the (III) boundary area). Therefore, the unevennesses of the surface state of the fixing roller151produced by the edge portions of the recording materials102having different main scan direction lengths are also eliminated.

Therefore, in this embodiment, the number of the recording materials102fed into the first fixing device150is stored for each 5 mm of the main scan direction length of the recording material102in the main assembly memory312. When the feeding number for any one of the main scan direction lengths exceeds the predetermined number (500, in this example), the CPU301executes the fixing element refreshing operation. Thereafter, the feeding numbers for all of the main scan direction lengths are reset (zero). When the feeding number for any one of the main-scanning lengths exceeds the predetermined number, the CPU301executes the fixing element refreshing operation.

The information of the main scan direction length of the recording material102is acquired from the content of the printing job received by the CPU301. When the operating portion180receives the printing job from the operator, it also receives the size of the recording material102(A3, for example) on which the image is to be formed, as one of the contents of the printing job.

By this, the glossiness unevenness on the output images can be suppressed, and also, the frequency of the fixing element refreshing operations is made lower than when the fixing element refreshing operation is carried out irrespective of the main scan direction length of the recording material102.

In this embodiment, the CPU301counts on the RAM302and stores in the main assembly memory312the feeding number of the recording materials102fed into the first fixing device150for each main scan direction length (for each widths). When the count of the recording material102for any one of the main scan direction lengths exceeds the predetermined value during the printing operation, the fixing element refreshing operation is carried out after completion of the currently executed printing job, and then the apparatus shifts into the stand-by mode. That is, if the count at the time of the completion of the image forming operation exceeds the predetermined value, the fixing element refreshing operation is executed after the completion of the current printing job. In addition, the CPU301acquires the ID of the first fixing device150from the resistor1154when the main switch is actuated or when the front door140is closed. The CPU301executes the fixing element refreshing operation, when the count of the feeding number corresponding to the ID of the first fixing device150for any one of the main scan direction lengths in the feeding number information stored in the main assembly memory312exceeds the predetermined value. Thereafter, the apparatus shifts to the stand-by mode.

The description will be made in conjunction with the flow charts ofFIGS. 15-18.

The operations of the flow charts are carried out by the CPU301functioning as the executing portion (recording portion) controlling the related mechanisms of the image forming apparatus300in accordance with the control program stored in the ROM303. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

(23.1. Sequence Upon Actuation of the Main Switch and Upon Closing the Front Door)

FIG. 15is a flow chart showing the operations from the actuation of a main switch to a stand-by mode.

With the actuation of the main switch101, the CPU301starts. The CPU301discriminates whether or not the first fixing device150is mounted in the image forming apparatus300(S101). If the first fixing device150is mounted on the apparatus, the CPU301can detect the ID of the fixing device. If the first fixing device150is not mounted, the operation returns to step S1101. In such a case, the CPU301may display a message, prompting the insertion of the first fixing device150, on the operating portion180. If the first fixing device150is mounted in the image forming apparatus300, the operation proceeds to step S1102.

The CPU301carries out the refreshing sequence shown inFIG. 17for the first fixing device150. The details of the operation will be described hereinafter.

In step S1103, the CPU301waits for the image forming apparatus300to become capable of carrying out the image forming operation. The CPU301carries out the preparing operation (starting-up operation) for the start of the image forming operation for various mechanisms, such as the first fixing device150and the image forming stations309, after the actuation of the main switch101. The temperature control for the fixing roller151is one of them, for example.

When the image forming apparatus300becomes capable of carrying out the image forming operation after the completion of the starting-up operations (Yes, S1103), the CPU301displays “printable” or the like on the operating portion180(S1104). By this, the operator is notified of the fact that the image forming apparatus300has become capable of carrying out the image forming operation. The apparatus is shifted into the stand-by mode.

FIG. 16is a flow chart showing the operations from the state in which a front door is open to the stand-by mode.

The opened and closed states of the front door140are detected by the CPU301on the basis of the signal from the opening and closing sensor305of the front door140. When the front door140is open, the CPU301waits for the closing of the front door140(S1201). When the front door140is open, the CPU301may display information to prompt the operator to close the front door140. When the CPU301detects the closing of the front door140(S1201), the operation proceeds to step S1202. Steps S1202-S1205are the same as steps S1101-S1104ofFIG. 15, and therefore, the description thereof is omitted. After step S1205, the operation proceeds to the stand-by mode.

FIG. 17is a flow chart of a refreshing sequence. The flow chart ofFIG. 17shows steps S1102and S1203, and the details of the refreshing sequence, which will be described hereinafter.

First, the CPU301acquires the ID of the first fixing device150mounted in the image forming apparatus300to identify the fixing device (S1301). The details of the method for acquiring the ID have been described in the foregoing, and therefore, the description thereof is omitted.

The CPU301makes the discrimination in step S1302on the basis of the feeding number information corresponding to the ID of the fixing device acquired in step S1301in the information stored in the main assembly memory312. In the main assembly memory312, the information indicative of the feeding numbers for each 5 mm of the main scanning direction length of the as shown inFIG. 19is stored, for example.

If the feeding number information (counts in the main assembly memory312) corresponding to the ID of the fixing device is less than the predetermined number (predetermined value) (500in this example) for all of the main scan direction lengths of the recording materials102, the operation proceeds to step S1303(S1302).

The CPU301sets the value of the feeding number (value stored in the main assembly memory312) for each of the main scan direction lengths for the ID of the fixing device as the value of the counter, in the RAM302for each of the main scan direction lengths (S1303).

On the other hand, in step S1302, the CPU301proceeds to step S1304, if a value (count) of the feeding number of the recording materials102for any one of main scan direction lengths corresponding to the ID of the fixing device exceeds the predetermined value (500 in this example).

In step S1304, the CPU301executes the above-described fixing element refreshing operation. By this, the surface of the fixing roller151is rubbed, so that the surface state is made even.

After the completion of the fixing element refreshing operation, the CPU301sets the counts for the respective main scan direction lengths to zero. That is, the value on the RAM302is reset (S1305).

The CPU (recording portion, writing portion)301records in the main assembly memory312that the feeding numbers for all of the main scan direction lengths are zero as the information of the feeding number, in correlation with the ID of the fixing device (S1306). More particularly, the values on the RAM302set in step S1305are copied in the main assembly memory312in correlation with the main scan direction lengths and the ID of the fixing device. By this, the CPU301is capable of executing the fixing element refreshing operation when the feeding number for any of the main scan direction lengths exceeds the predetermined value (500 in this example) after the execution of the fixing element refreshing operation again. After the execution of the fixing element refreshing operation, the CPU301sets the feeding numbers for all of the main scan direction lengths corresponding to the ID of the first fixing device150in the main assembly memory312, to zero. By this, the information indicative of the execution of the fixing element refreshing operation is recorded in the main assembly memory312in correlation with the ID of the first fixing device150. In this manner, the fixing element refreshing operation can be carried out repeatedly, for each exceeding of the feeding number for any one of the main scan direction lengths of the recording materials102. The information of the number may be written in the main assembly memory312in step S1306with the CPU301detecting the opening of the front door140on the basis of the signal from the opening and closing sensor305in the stand-by mode state. In addition, the information of the feeding number may be written in the main assembly memory312in step S1306with the deactuation of the main switch101. This is because the exchange of the first fixing device150necessitates the opening of the front door140.

(23.3. Sequence for Recording Material Counting)

FIG. 18is a flow chart of counting of the recording materials. More particularly, it is a flow chart of printing job execution by the image forming apparatus300.

In the stand-by mode in which the image forming apparatus300is capable of carrying out the printing operation, the image forming apparatus300waits for the printing job from the operating portion180or an external PC or the like through the outside I/F portion304(S1401). At this time, the image forming apparatus300displays a selection screen for selecting the kind of the recording material102on the operating portion180or a display screen of the external PC, and receives the kind of the recording material102to be used for the printing by the operator as a content of the printing job.

When the printing job is received (Yes, S1401), the CPU301controls the mechanisms, such as the image forming stations120-123, the first fixing device150, the second fixing device170, or the like, of the image forming apparatus300, and starts the image forming process operation of the image forming apparatus300. In other words, the printing job is started (S1402).

If the CPU (counter)301detects the feeding of the recording material102to the first fixing device150(S1404, Yes) in the stage in which the printing job is not completed (in S1403, No), the CPU301increments the count on the RAM302. The CPU301increments the count corresponding to the main scan direction length of the fed recording material102, of the counts on the RAM302. The information of the main scan direction length of the fed recording material102is acquired by the CPU301on the basis of the content of the printing job in step S1401. The CPU301detects the feeding of the recording material102to the first fixing device150depending on the signal from the sensor155.

On the other hand, if the feeding of the recording material102to the first fixing device150is not detected in step S1404, the CPU301does not increment the count, and proceeds to step S1406. This occurs, for example, in the case that after the detection of the passage of the recording material102, the passage of the next recording material102is not detected after elapse of predetermined time, despite the non-completion of the printing job. The predetermined time period is counted by the timer307.

When no sheet jamming in the image forming apparatus300is detected (S1406, No), the CPU301continues the operation for the printing job until the completion of the printing job, while repeating the operations of steps S1404and S1405.

When the CPU301detects the jamming in the image forming apparatus300(S1406), the CPU301records the count on the RAM302for the main scan direction length in correlation with the ID of the first fixing device150, as the information of the feeding number (S1407) The ID of the first fixing device150has already been acquired in step S1301of the refreshing sequence ofFIG. 17, which is executed in response to the actuation of the main switch101or the closure of the front door140. The CPU301detects the jamming in the image forming apparatus300on the basis of the signals from the sensor group306. For example, in the case that, upon elapse of a predetermined time from the detection of the recording material102by the sensor155disposed in the upstream side with respect to the feeding direction of the recording material102, the sensor153disposed in the downstream side does not detect the passage of the recording material102, the CPU301discriminates that the recording material102stagnates in the portion between the two sensors. The predetermined time is counted by the timer307.

When the jamming occurs in the image forming apparatus300, the CPU301interrupts the printing job. At this time, the jammed recording material stagnating in the feeding path of the image forming apparatus300is cleared by the operator, and therefore, the front door140or the like is opened.

The CPU301waits for the front door140to close (S1408). When the CPU301detects the closing of the front door140on the basis of the signal from the opening and closing sensor305(S1408), the refreshing sequence is carried out (S1409).

The refreshing sequence in step S1409corresponds to the flow shown inFIG. 17. In this refreshing sequence, the ID of the first fixing device150is read out (S1301) as described above. The ID of the first fixing device150is read out because there is a possibility that the first fixing device150is exchanged when the front door140is opened for the jam clearance.

In step S1410, the CPU301waits for the image forming apparatus300to become capable of carrying out the image forming operation. The CPU301carries out the preparing operation (starting-up operations) for resuming the image forming operation for various mechanisms such as the first fixing device150, the image forming station309and the like of the image forming apparatus300after the clearance of the jammed recording material. The temperature control for the fixing roller151is one of them, for example.

When the image forming apparatus300becomes capable of resuming the image forming operation after the completion of the starting-up operations (Yes, S1410), the CPU301displays “printable” or the like on the operating portion180(S1411). By this, the operator is notified of the fact that the image forming apparatus300has become capable of carrying out the image forming operation. Thereafter, the operation returns to step S1403, and the CPU301resumes the operations for the remaining printing job and continues up to the completion of the printing job.

When the printing job is completed (S1403, Yes), the CPU301discriminates whether or not any one of the feeding numbers for all the main scan direction lengths exceeds the predetermined value (500 in this example) (S1412).

If the result of the discrimination is negative, that is, if the values of the feeding numbers for all of the main scan direction lengths stored in the RAM302are less than the predetermined value (500 in this example), the CPU301proceeds to step S1415.

If the result of the discrimination is affirmative, that is, if a value of the feeding number for any one of the main scan direction lengths exceeds the predetermined value (500 in this example), the CPU301executes the fixing element refreshing operation (S1413). After the completion of the fixing element refreshing operation, the CPU301resets the values for all of the main scan direction lengths on the RAM302to zero. That is, the counter values are reset (S1414).

In step S1415, the CPU301records the count of the RAM302in the memory154for each main scan direction lengths in correlation with the ID of the first fixing device150, as the information of the feeding number. As the operation goes through the process of step S1414, the feeding numbers for all the main scan direction lengths as the information of the feeding number become zero.

The CPU301displays “printable” on the operating portion180to notify the operator of the operativity of the image forming apparatus300(S1416). The apparatus is shifted into the stand-by mode.

By storing the information of the feeding number in the main assembly memory312in correlation with the ID of the first fixing device150before entering the stand-by mode, a correct feeding number can be stored in the memory154even when the first fixing device150is removed from the image forming apparatus300during the stand-by mode. Thus, even when the first fixing device150is taken out of the image forming apparatus300during the stand-by mode, more accurate feeding number information can be stored in the main assembly memory312.

The writing in the main assembly memory312in step S1407may be effected only when the jamming occurs in first fixing device150and/or the second fixing device170in step S1406. It is expected for the front door140to be opened by the operator after the occurrence of the jamming, because the jamming occurs in the fixing portion. This is because, in the case of the jamming in the fixing portion, the operator clears the recording material102stagnating in the first fixing device150and/or the second fixing device170. The liability that the first fixing device150is exchanged by the operator arises when the front door140is opened.

In such a case, the sensors153and155function as the jam detecting portion. The sensors may be an optical sensor, for example. The CPU301receives the signals from the sensors153and/or155to detect the stagnation of the recording material102in the first fixing device150(jamming in the fixing portion). For example, in the case that, after the elapse of the predetermined period after the passage of the recording material102by the sensor155disposed at an upstream side with respect to the feeding direction of the recording material102, the downstream side sensor153does not detect the passage of the recording material102, the CPU301discriminates that the recording material102stagnates between the sensors155and153. The predetermined time is counted by the timer307.

In the fixing element refreshing operation in steps S1304and S1413, the duration of the rubbing treatment by the refreshing roller156may not be constant. That is, the CPU301carries out the rubbing treatment for a time period corresponding to the amount, beyond the predetermined count (500in this example), of the count (excess amount) of the feeding number for the main scan direction length.

For example, when the predetermined value in steps S1412and S1413is set to 500, and when the count is 500, the rubbing treatment duration is 30 sec, and when the count is 600, the rubbing treatment duration is 40 sec.

In this case, the duration of the rubbing treatment may be gradually or stepwisely increased with the increase of the excess amount of the count. The data (table, function or the like) for providing the correspondence between the excess amount of the count relative to the predetermined value and the rubbing treatment duration is stored in the ROM303beforehand.

As described hereinbefore, the exchange of the first fixing device150by the operator necessitates the opening and closing of the front door140of the image forming apparatus300. When the front door140of the image forming apparatus300is opened by the operator, the first fixing device150may be exchanged. In addition, when the main switch101is off, the first fixing device150may have been exchanged. Therefore, whenever the actuation of the main switch101of the image forming apparatus100and/or the closure of the front door140occurs, the CPU301acquires the ID of the first fixing device150. Then, the discrimination is made in step S1302on the basis of the information of the feeding number corresponding to the ID of the feeding number information stored in the main assembly memory312. By this, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of the more accurate information of the feeding number, and therefore, the deterioration of the image quality of the image on the output recording material102can be suppressed.

In the description of the foregoing embodiment, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170.

In Embodiment 12, when the count of the feeding number for any one of the main-scan direction lengths exceeds the predetermined value during the printing operation, the CPU301carries out the fixing element refreshing operation after the completion of the printing job, and then, the apparatus shifts to the stand-by mode.

In Embodiment 13, when the total count of the feeding numbers for the main-scan direction lengths exceeds the predetermined value, the CPU301executes the fixing element refreshing operation in the period of the printing job.

In Embodiment 12, the CPU301counts the feeding number for the main scan direction length on the RAM302, and stores the count in main assembly memory312.

In this Embodiment 13, the CPU301counts the feeding number on the main assembly memory312for the first fixing device150. The CPU (recording portion, writing portion)301renews and records the count of the feeding number corresponding to the ID of the writing portion on the main assembly memory312, for each feeding of the recording material102to the first fixing device150on the basis of the signal from the sensor155. In this manner, the CPU301functions as a counter.

The same applies to the second fixing device170.

In the description of this embodiment, the same reference numerals as in Embodiment 12 are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

In the following, the description will be made with respect to the first fixing device150. The same applies to the second fixing device170.

In the main assembly memory312, the number of the recording materials102fed into the first fixing device150is stored for each 5 mm of the main scan direction length of the recording material102in correlation with the ID of the first fixing device150. After the total of the feeding numbers for the respective main scan direction lengths exceeds the predetermined value (500 in this example), the fixing element refreshing operation is executed for the first fixing device150, by the CPU301. Thereafter, the feeding numbers for all of the main scan direction lengths correlated with the ID of the first fixing device150are reset (zero). When the total count exceeds the predetermined value (500 in this example), again, the CPU301executes the fixing element refreshing operation.

In place of counting the recording materials for each main scan direction length on the main assembly memory312, all the recording materials fed into the first fixing device150may be counted irrespective of the main scan direction length.

The fixing element refreshing operation in this embodiment (in the period of the execution of the printing job) may be carried out after the interruption of the printing job (that is, by expanding the interval between the adjacent recording materials102fed into the first fixing device150), or while printing is continuously carried out (that is, while executing the fixing process operation). However, the former is preferable. In such a case, the likelihood of the production of the disturbance of the toner image during the fixing process operation attributable to the vibration or the like caused by the contact of the refreshing roller156to the fixing roller151for the execution of the fixing element refreshing operation can be reduced.

Referring to flow charts ofFIGS. 15 and 16of Embodiment 1 and the flow charts ofFIGS. 20 and 21, the description will be made. The operations in flow chart are carried out by the CPU301as the executing portion controlling the operation of the various mechanisms of the image forming apparatus300on the basis of control programs stored in the ROM303. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

(24.1. Sequence Upon Actuation of the Main Switch and Upon Closing the Front Door)

The sequence upon actuation of the main switch101and upon closing the front door140will be described referring to the flowchart ofFIGS. 15 and 16.

In this embodiment, in steps S1102(FIG. 15) and S1203(FIG. 16), the operation proceeds to the refreshing sequence ofFIG. 20.

As to the other structures, they are the same as those of Embodiment 1, and the descriptions thereof are omitted for the sake of simplicity.

FIG. 20is a flow chart of a refreshing sequence. The flow chart ofFIG. 20shows the details of step S1102(FIG. 15), and step S1203(FIG. 16), and the refreshing sequence in step S1608, which will be described hereinafter.

A step S1501is the same as step S1301ofFIG. 17, and therefore, the description thereof is omitted.

The CPU301makes the discrimination in step S1502on the basis of the feeding number information corresponding to the ID of the fixing device acquired in step S1501in the information stored in the main assembly memory312.

If the total (total count) of the feeding numbers for all of the main scan direction lengths in correlation with the ID of the first fixing device150exceeds a predetermined number (500in this embodiment) (S1502), the CPU301proceeds to a step S1503.

Step S1503is the same as step S1304ofFIG. 17, and therefore, the description thereof is omitted.

After the completion of the fixing element refreshing operation, the CPU301sets the counts for all of the main scan direction lengths to zero on the main assembly memory312. That is, the counter values are reset (S1504).

On the other hand, if the discrimination in the step S1502is negative, that is, the total count of the feeding number information for all of the main scan direction lengths stored in the main assembly memory312is not more than the predetermined value (500 in this example), the CPU301completes the refreshing sequence without executing the fixing element refreshing operation.

(24.3. Sequence for Recording Material Counting)

FIG. 21is a flow chart of counting of the recording materials. More particularly, it is a flow chart of printing job execution by the image forming apparatus300.

Steps S1601and S1602are the same as steps S1401and S1402(FIG. 18), and therefore, the description is omitted.

If the CPU301detects that the recording material102is fed to the first fixing device150(S1604, Yes) before the printing job is finished (S1603, No), the CPU301increments the count of the main assembly memory312. The CPU301increments the count for the ID of the first fixing device150. The ID of the first fixing device150has already been acquired in step S1501of the refreshing sequence ofFIG. 20, which is executed in response to the actuation of the main switch101or the closure of the front door140. The CPU301increments the count for the main scan direction length of the recording material102fed to the fixing device, of the counts stored in the main assembly memory312. The information of the main scan direction length of the fed recording material102is acquired by the CPU301on the basis of the content of the printing job in step S1601. The CPU301detects the feeding of the recording material102to the first fixing device150depending on the signal from the sensor155.

On the other hand, if the feeding of the recording material102to the first fixing device150is not detected in step S1604, the CPU301does not increment the count, and proceeds to step S1606. This occurs, for example, in the case that after the detection of the passage of the recording material102, the passage of the next recording material102is not detected after elapse of predetermined time, despite the non-completion of the printing job. The predetermined time period is counted by the timer307.

When the jamming occurs in the image forming apparatus300(S1606, Yes), the CPU301interrupts the printing job. At this time, the jammed recording material stagnating in the feeding path of the image forming apparatus300is cleared by the operator, and therefore, the front door140or the like is opened.

The CPU301waits for the front door140to close (S1607). When the CPU301detects the closing of the front door140on the basis of the signal from the opening and closing sensor305(S1607), the refreshing sequence is carried out (S1608).

The refreshing sequence in step S1608corresponds to the flow shown inFIG. 20. In the refreshing sequence, the ID of the first fixing device150is acquired (S1501), as described in the foregoing. The ID of the first fixing device150is acquired because there is a possibility that the first fixing device150is exchanged when the front door140is opened for the jam clearance.

Step S1609is the same as step S1410, and therefore, the description thereof is omitted.

When the image forming apparatus300becomes capable of resuming the image forming operation after the completion of the starting-up operations (Yes, S1609), the CPU301displays “printable” or the like on the operating portion180(S411). By this, the operator is notified of the fact the image forming apparatus300has become capable of carrying out the image forming operation.

Thereafter, the operation returns to step S1603, and the CPU301resumes the operations for the remaining printing job and continues up to the completion of the printing job.

If the CPU301does not detect occurrence of jamming in the image forming apparatus300(S1606, No), the CPU301discriminates whether or not the total count of the feeding numbers for all of the main scan direction lengths correlated with the first fixing device150in the main assembly memory312exceeds the predetermined value (500 in this example) (S1611).

In step S1611, if the total count exceeds the predetermined value (500 in this example), the CPU301proceeds to a step S1603, and the printing operation is continued until the printing job is finished.

When the total count of the main assembly memory312exceeds the predetermined value (500 in this example) in S1611, the CPU301executes the fixing element refreshing operation (S1612).

When the fixing element refreshing operation is completed, the CPU301sets the counts of the feeding number corresponding to the first fixing device150on the main assembly memory312to zero for all main scan direction lengths. That is, the counter values are reset (S1613).

Thereafter, the operation returns to step S1603, where the CPU301continues the printing job until the printing job is finished.

After the printing job is completed (S1603, Yes), the CPU301shifts to the stand-by mode.

In this embodiment, the counts of the feeding numbers of the recording materials102are managed on the main assembly memory312. The CPU301records the counts of the feeding numbers in the memory154for each feeding of the recording material102to the first fixing device150. By this, even when the first fixing device150is taken out of the image forming apparatus300, more accurate feeding number information can be stored in the main assembly memory312.

As described hereinbefore, the exchange of the first fixing device150by the operator necessitates the opening and closing of the front door140of the image forming apparatus300. When the front door140of the image forming apparatus300is opened by the operator, the first fixing device150may be exchanged. In addition, when the main switch101is off, the first fixing device150may have been exchanged. Therefore, whenever the actuation of the main switch101of the image forming apparatus300and/or the closure of the front door140occurs, the CPU301acquires the ID of the first fixing device150. The CPU301counts the feeding number on the basis of the count in the main assembly memory312. By this, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of the more accurate information of the feeding number, and therefore, the deterioration of the image quality of the image on the output recording material102can be suppressed.

In the description of the foregoing embodiment, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170.

In Embodiment 12, the CPU301stores the feeding number information in the main assembly memory312in correlation with the ID of a fixing device.

In this embodiment, the CPU301stores the feeding number information in a storing device200in correlation with the ID of the fixing device (image forming system).

The storing device200, shown inFIG. 14, is connected communicatably with the image forming apparatus300through a network cable. The storing device200is a server-computer comprising a rewritable non-volatile memory, an external I/F portion304, and a communication circuit connected with the network, and functions as a storing server for storing information of the image forming apparatus300. The storing device200comprises a CPU301for controlling the storing device200and a ROM for storing control programs to be executed by the CPU301. The CPU301of the storing device200records the information of the image forming apparatus300received by the communication circuit through the network, supplying to the image forming apparatus300the information of the memory in accordance with the instructions of the image forming apparatus300received by the communication circuit through the network.

The communication is described as being made between the storing device200and the image forming apparatus300through the network cable, but it can be made by wireless communication.

In this embodiment, the CPU301functions as a recording portion (writing portion).

The CPU301stores the feeding number information in combination with the ID of the first fixing device150in the memory of the storing device200connected with the external I/F portion304, through the network, and acquires the information stored in the memory of the storing device200.

This embodiment is used with Embodiment 12.

When the main switch101is actuated or when the front door140is closed, the CPU301acquires the ID of the first fixing device150from the discrimination portion (resistor1154) of the first fixing device150.

The CPU301stores the number (feeding number) of the recording materials102fed to the first fixing device150in correlation with the main-scanning direction length, as the information of the feeding number to be stored in the memory of the storing device200. The CPU301stores the feeding number for the main scan direction length in correlation with the ID of the first fixing device150in the storing device200.

When anyone of the counts of the feeding number for the main scan direction lengths correlated with the ID of the first fixing device150, or the feeding number information stored in the storing device200exceeds a predetermined value, the CPU301executes the fixing element refreshing operation. Thereafter, the apparatus shifts to the stand-by mode.

When the feeding number information corresponding to the ID of the first fixing device150mounted in the storing device200is less than the predetermined value, with respect to the feeding number counts for all of the main scan direction lengths, the CPU301, as the counter, counts up on the basis of the information in the storing device200. That is, the CPU301, as the counter, counts the recording material102(feeding number) fed to the first fixing device150on the basis of the information corresponding to the ID of the first fixing device150stored in the storing device200.

The specific operation flow is the same as with above-described Embodiment 12, and therefore, the detailed description thereof is omitted for the sake of simplicity. For this embodiment, the main assembly memory312in Embodiment 12 should read storing device200. As regards the flow chart ofFIGS. 15-18, the description above the regarding the memory (S1306ofFIG. 17, for example) should be read as that of the storing device200.

With the structure of this embodiment, too, the CPU301can count the feeding number on the basis of information corresponding to the ID of the first fixing device150stored in the storing device200. In other words, the fixing element refreshing operation for the first fixing device150can be carried out on the basis of more accurate number information, and the deterioration of the output image quality on the recording material102can be suppressed.

(25. The Case in which the User Uses a Plurality of Image Forming Apparatuses)

The storing device200may be connected with a plurality of image forming apparatuses into which the first fixing device150is mountable, through a network. The structures of the image forming apparatuses are the same as that of the image forming apparatus300, and the detailed description is omitted.

In this case, the CPU301of the image forming apparatus300can execute the fixing element refreshing operation on the basis of the feeding number, taking into account the number of the recording materials fed to the first fixing device150in another image forming apparatus. By this, the fixing element refreshing operation can be executed for the first fixing device150on the basis of more accurate number of information and at a more appropriate timing.

The description will be made taking a specific situation. That is, the fixing device to be replaced is the first fixing device150.

For example, the user uses two image forming apparatuses300(image forming apparatus P and image forming apparatus Q). The fixing device A is usable with either of the image forming apparatuses P, Q as the first fixing device150. The predetermined value is 500. That is, the CPUs of the image forming apparatuses P, Q execute the fixing element refreshing operation for the first fixing device150when the number of the recording materials102fed to the first fixing device150exceeds 500.

The fixing device A is mounted in the image forming apparatus P. It is assumed that when the printing job of the image forming apparatus P is completed, the feeding number to the fixing device A is 450.

Suppose the operator then uses this fixing device A in the other image forming apparatus Q, as the first fixing device150. The operator takes the fixing device A out of the image forming apparatus P and mounts it in the image forming apparatus Q. Then, a printing job including 100 prints is carried out in the image forming apparatus Q.

With the structure in which the feeding number information is stored in the main assembly memory312as in Embodiment 12, the CPU301of the image forming apparatus Q executes the fixing element refreshing operation on the basis of the information of the main assembly memory312of the image forming apparatus Q. Therefore, if the feeding number information for the fixing device A stored in the main assembly memory312upon the mounting of the fixing device in the image forming apparatus Q is zero, the fixing element refreshing operation is not executed even if the printing job of 100 sheets is completed.

However, the fixing device A has already processed 450 recording materials102in the image forming apparatus P, and therefore, when the printing job of 100 sheets is completed in the image forming apparatus Q, the feeding number through the fixing device A exceeds the predetermined value (500) at the time of the completion of the printing job in the image forming apparatus Q. If the fixing process is carried out using the fixing device A after the completion of the 100 sheets printing job, the output image is likely to have a glossiness unevenness. It is desirable that the fixing element refreshing operation is carried out for the fixing device A in such a case, too.

In this embodiment, the image forming apparatuses P, Q are connected with a storing device200through the network, and the feeding number information is stored in the storing device200, and the fixing element refreshing operation can be properly executed in the above-described case. By this, the production of the glossiness unevenness can be assuredly suppressed.

Specific operations will be described referring toFIG. 17of Embodiment 12.

The count of the feeding number to the fixing device A is stored in a memory of the storing device200by the image forming apparatus P (S1306ofFIG. 17and S1407, S1415ofFIG. 18).

The operator takes the fixing device A out of the image forming apparatus P and mounts it in the image forming apparatus Q. Thereafter, the main switch101of the image forming apparatus Q is actuated, and the CPU301of the image forming apparatus Q checks the mounting of the first fixing device150(S1101ofFIG. 15) and proceeds to the refreshing sequence ofFIG. 17(S1102ofFIG. 15).

The CPU301of the image forming apparatus Q makes the discrimination for the fixing device A on the basis of the feeding number information acquired from the storing device200. In addition, in step S1303ofFIG. 17, the CPU301of the image forming apparatus Q sets the feeding number of the fixing device A acquired from the storing device200in a counter314of the image forming apparatus Q.

By doing so, the CPU301of the image forming apparatus Q can properly count the feeding number of the recording materials102to the fixing device A. Therefore, the fixing element refreshing operation can be properly executed for the fixing device A, and therefore, the deterioration of the image quality can be suppressed.

In the foregoing description, the first fixing device150is taken as an example, but the same applies to the second fixing device170.

In this embodiment, the structure (image forming system) of storing the feeding number information in the storing device200is applied to Embodiment 12, but the same may be applied to Embodiment 13. The specific structures and operations are similar to those of Embodiment 13, and therefore, the description thereof is omitted. For such an example, the main assembly memory312in Embodiment 12 should read as the storing device200.

In Embodiments 12 and 13, the CPU301stores the number information of the recording materials102fed to the first fixing device150and the second fixing device170in the main assembly memory312. In Embodiment 14, the CPU301stores the number information of the recording materials102fed to the first fixing device150and the second fixing device170in the storing device200. Concurrently with the writing of the information in main assembly memory312by the CPU301, the same information may be stored in the storing device200by the CPU301.

The image forming apparatus300may be set at a mode not executing the above-described fixing element refreshing operation, by the setting of the user. In such a case, the operating portion180is provided with a selector which displays a display for the selection between the mode in which the fixing element refreshing operation is executed and the mode in which it is not executed. The user is capable of selecting one of the modes through the operating portion180. The information of the selected mode is stored in the main assembly memory312as the set information of the image forming apparatus300. The operation program to be executed when the fixing element refreshing operation non-executing mode is selected is stored in the ROM303. When such a mode is selected, the CPU301executes the program.

The fixing element refreshing operation is necessary in order to suppress the glossiness non-uniformity due to the difference in the surface roughness between the (I) non-passing portion, the (II) passing portion, and the (III) boundary area of the fixing roller151, as described hereinbefore. The difference in the surface roughness of the fixing roller151appears as the glossiness unevenness when the recording material102passes through the nip in contact with the (I) non-passing portion, the (II) passing portion, and the (III) boundary area of the fixing roller151. Therefore, the glossiness unevenness can be suppressed by using the different fixing device having the same structure, for the respective main scan direction length of the recording material102as the first fixing device150. In view of this, some user who is concerned with the glossiness property evenness prepares the fixing devices for respective main scan direction lengths of the recording material102in order to avoid the deterioration of the print quality.

In such a case, that is, due to the glossiness unevenness caused by the edge portions of the recording materials102, it is desirable not to execute the fixing element refreshing operation to avoid the fine scores provided by the refreshing roller156, which influence the glossiness property of the image.

By making the modes (execution and non-execution of the fixing element refreshing operation) selectable by the user, the apparatus can meet wider needs of the users.

With respect to the Embodiments 12-16, the contact of the end portions of the recording materials102with the fixing roller151is taken as the cause of the difference in glossiness on the fixed image, but the causes are not limited to that. For example, a separation claw contacting the fixing roller151may be provided to prevent the recording material102from wrapping around the fixing roller151.

In such a case, with the cumulation of the fixing process, there is a likelihood that contact damage may occur by the contact of the separation claw to the surface of the fixing roller151. In the case that a plurality of separation claws are provided at intervals in the longitudinal direction (axial direction) of the fixing roller151, the surface of the fixing roller151is roughened adjacent to the contact position with the separation claw, with the result of unevenness of the surface state over the length of the fixing roller151. As a result, the glossiness difference may arise on the fixed image.

Even in such a case, the influence to the image quality by the contact damage can be reduced by providing the refreshing roller156and executing the fixing element refreshing operation.

In Embodiments 12-17, the refreshing roller156is provided for the fixing roller151to effect the rubbing treatment to the surface of the fixing member, but the rubbing rotatable member is provided for the surface of the pressing belt152and/or the pressing roller172to effect the rubbing treatment thereto.

In the exchangeable fixing device system, the user exchanges the fixing devices depending on the kind of the recording material102or the preference. In such a case, there is a possibility that a better quality print can be provided if the fixing device not selected by the operator is used, that is, there is a likelihood that the advantage of the exchanging system is not enjoyed. In this embodiment, the image forming apparatus300notifies the operator of the matching between the selected recording material102and the selected fixing device.

In the following, the description will be made referring to an Embodiment 1 (FIGS. 17 and 18). The other structures are the same as in Embodiment 1, and therefore, the detailed description thereof is omitted for simplicity. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

The first fixing device150is provided with a resistor functioning as a limiting information portion. For the description of this case, the resistor1154ofFIG. 14should read as the resistor functioning as the limiting information portion. The fixing device prepared outside the image forming apparatus300as a replacement fixing device is also provided with a resistor as the limiting information portion. The resistance value is different depending on the kind of the recording material102for which the fixing process of the first fixing device150is limited, and functions as the information for limiting the kind of the recording material102for use in the fixing process of the first fixing device150. The method for acquiring the limiting information is the same as the method for acquiring the ID of the above-described fixing device, and the description thereof is omitted.

In the main assembly memory312, the information indicative of the kind of the recording material102to be limited in the fixing process corresponding to the resistance value (limiting information) of the memory (limiting information portion) is stored beforehand. For example, when the resistance value is R4, the fixing on an envelope is prevented, and when the resistance value is R5, the fixing on a thick sheet is prevented.

In a step S10301ofFIG. 17, the CPU301acquires the resistance value (limiting information) of the resistor (limiting information portion) of the first fixing device150together with acquiring the ID of the first fixing device150mounted in the image forming apparatus300. On the basis of the limiting information and the kind of the limited recording material information stored in the main assembly memory312, the CPU301determines the kind of the recording material102which is to be prevented in the fixing operation of the first fixing device150.

In step S401ofFIG. 9, when the CPU301receives the printing job from the operator, the CPU301makes the kinds of the recording material102not suitable for the first fixing device150non-selectable on the selection screen.

Thus, the printing operation using improper first fixing device150can be prevented, thus assuring high quality prints.

The information corresponding to the kinds of the recording material102to be prevented may not be stored in the main assembly memory312in combination with the limiting information. For example, the program executed by the CPU301may prevent the fixing process on the recording material102depending on the resistance value of the resistor (limiting information portion). In such a case, the program is stored in the ROM303.

The foregoing description has been made with respect to the first fixing device150, but it is applicable to the second fixing device170, and therefore, the description as to the second fixing device170will be omitted.

In this embodiment, a resistor is used as the limiting information portion, but this is not limiting to the present invention and the following is an alternative structure.

For example, the limiting information portion provided on the fixing device (first fixing device150, second fixing device170, and replacement fixing device) may be DIP switch including a plurality of switches. In such a case, the switches different depending on the fixing devices are in ON state beforehand as the limiting information, and the CPU301determines the kind of the recording material102to be prevented on the basis of the signal from the ON state switches. The other structures are the same as those of the DIP switch as the discrimination portion described hereinbefore.

The limiting information portion provided on the fixing device (first fixing device150, second fixing device170, and replacement fixing device) may indicate the usage, for example, “for envelope”, or the kind and/or usage of the fixing device (limitation information). In such a case, the memory is a rewritable non-volatile memory such as EEPROM, flash memory or the like. The CPU301reads out the limiting information from the memory to determine the kind of the recording material102to be prevented. In this case, the information corresponding to the limited recording material102may be stored in the memory as the limiting information portion provided on the fixing device not in the main assembly memory312.

In this embodiment, the limiting information portion and the discrimination portion are separate members on the fixing device, but one resistor or memory may include the limiting information portion and the discrimination portion.

In addition, this embodiment has been described as being incorporated in Embodiment 12, but may be incorporated in Embodiment 13 or 14. The description is omitted because it also applies to the case where Embodiment 13 or Embodiment 14 is modified.

In Embodiments 12-19, the operating portion180is provided with a display screen and a selection key, but the display screen may be a touch panel which also functions as a selector.

In the foregoing embodiments, the image forming apparatus300comprises both of the first fixing device150and the second fixing device170(tandem fixing). However, the present invention is applicable to an image forming apparatus300comprising only one fixing device150.

In the Embodiments 12-21, the image forming apparatus100comprises the image forming stations (120-123) for forming yellow, magenta, cyan and black toner images (color image forming apparatus), but the present invention is applicable to a monochromatic image forming apparatus. For example, there is a monochromatic for forming the toner images in black only.

In the Embodiments 12-22, the image forming apparatus300comprises an intermediary transfer belt115as an intermediary transfer member (intermediary transfer type), but the present invention is applicable to a direct transfer type apparatus as follows.

In such a case, the image forming station309includes the image forming stations (120-123) and a transfer feeding belt functioning as a transfer portion. The image forming stations (120-123) can be contacted by the transfer feeding belt. The image forming apparatus300feeds the recording material102from a recording material accommodating portion103to the transfer feeding belt. The transfer feeding belt electrostatically attracts the recording material102and carries it to a position where the recording material102faces the image forming station, and a transfer roller is provided in the inside of the belt. The transfer roller transfers the toner image formed on the image bearing member onto the recording material102carried on the transfer feeding belt. By this, the toner image (unfixed) is formed on the recording material102.

(26. General Arrangement of Image Forming Apparatus)

FIG. 22is a sectional view of an example of an image forming apparatus according to Embodiments 24-37.

In the description of these embodiments, the same reference numerals as in Embodiment 1 are assigned to the elements having the corresponding functions, and the detailed description thereof is omitted for simplicity. That is, the description of the image forming apparatus300, and of the image forming apparatus100of the foregoing embodiments should read as the image forming apparatus400.

The front door140as an opening and closing portion is provided for the opening of the main assembly400A of the image forming apparatus400for mounting a fixing device (first fixing device150, second fixing device170) to a mounting portion (first mounting portion141, second mounting portion142).

The image forming apparatus400is provided with an opening and closing sensor (optical sensor)305(FIG. 23) as a sensor for sensing a closed state of the front door140. The opening and closing sensor305and the CPU301(FIG. 23) function as an opening and closing detecting portion. The front door140is provided with a projection (unshown), which is inserted into a receiving portion (unshown) of the main assembly400A of the image forming apparatus400by the closing of the front door140. The CPU301detects the closing of the front door140on the basis of a signal produced by the opening and closing sensor305upon the insertion of the projection into the receiving portion. On the other hand, when no output signal is produced by the opening and closing sensor305, the CPU301detects that the front door140is open. In an alternative structure, the CPU301detects the opening of the front door140on the basis of the signal produced by the opening and closing sensor305upon the opening of the front door140, and the CPU301detects that the front door140is closed when the signal from the sensor305is not detected.

(27. Structure of Control System)

FIG. 23is a block diagram of an example of a structure of the control system in Embodiments 24-37. In the description of this embodiment, the same reference numerals as in the foregoing embodiments are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

The image forming apparatus400(FIG. 22) is provided with a CPU301, a RAM302, and a ROM303for controlling the operation of the image forming apparatus400.

The CPU301, functioning as a controller, carries out a basic control of the image forming apparatus400by executing control programs stored in the ROM303. The CPU301uses the RAM302as a work area for executing the processing of the control program.

The CPU301is electrically connected with the RAM302and the ROM303, and various mechanisms to be controlled.

In addition, the CPU301functions also as a counter for counting the recording materials102fed into the first fixing device150or second fixing device170. The specific structure will be described hereinafter.

An external I/F portion304is a communication circuit for communication with an external device connected through a network (LAN and/or WAN). The examples of the external device include a personal computer (PC) and another image forming apparatus or the like.

The CPU301is connected with the opening and closing sensor305to detect whether or not the front door140is closed.

The sensor group306including sensors153,155,173, and175, shown inFIG. 22, is disposed along the feeding path, by which the CPU301detects the presence, absence and passing of the recording material.

In addition, the CPU301is connected with a timer307. The timer307functions as a clock portion for measuring a time period. As will be described hereinafter, it counts the time for detection of a jammed sheet, and/or for a fixing element refreshing operation.

The CPU301is connected with the clock313. The clock313functions as an output portion for outputting time information. The CPU301acquires the time information indicated by the clock313.

The CPU301is connected with a counter314. The CPU301receives the instructions of switching of the display content on the display screen and other operations, given by the operator at the selection keys of the operating portion180. The CPU301displays, on the display screen of the operating portion180, the status of operation of the image forming apparatus400, an operation mode selected by the selection key, and so on.

The CPU301is connected with a feeding portion308to control feeding of the recording material102. The feeding portion308includes a supply portion for feeding the recording material102from the recording material accommodating portion103to the feeding path, feeding rollers for feeding the recording material102on the feeding path, and flappers (flappers131,132,133, inFIG. 22) for the feeding paths.

In addition, the CPU301is connected with the image forming station309which will be described hereinafter to control the image forming station309.

The memory310of the fixing device includes a memory154of the first fixing device150mounted in the image forming apparatus400, and a memory174of the second fixing device170mounted to the image forming apparatus400. The CPU301is connected with the memories154,174of the first fixing device150and the second fixing device170mounted in the image forming apparatus400and writes in and reads out of the memories154,174.

The CPU301is connected with a discrimination member311. The discrimination member311will be described in the description of the embodiment which will be described hereinafter.

The CPU301is connected with a main assembly memory312. The main assembly memory312is rewritable non-volatile memory and may be integral with the RAM302.

The CPU301is connected with a mechanism group X of the first fixing device150mounted in the image forming apparatus400to effect a temperature adjustment control and fixing element refreshing operation. The mechanism group X includes a temperature sensor320, a heater321, a moving mechanism322, a motor323, and a refreshing roller moving mechanism325.

The temperature sensor320includes a plurality of temperature sensors provided in the first fixing device150, including a thermister159(FIG. 3), and a thermister (unshown) for the pressing belt152.

The heater321includes a plurality of heaters provided in the first fixing device150, including a halogen heater161(FIG. 3), and a halogen heater (unshown) provided in the heating roller163.

The CPU301is connected with a mechanism group X of the second fixing device170mounted in the image forming apparatus400to effect temperature adjustment control and the fixing element refreshing operation. The mechanism group X for the second fixing device170is substantially the same as the mechanism group X of the first fixing device150, and therefore, the detailed description thereof is omitted by applying the same reference numerals to the corresponding elements. (In the description of the mechanism group X for the first fixing device150, the first fixing device150, the pressing belt152, and the heating roller163correspond to the second fixing device170, the pressing roller172, and the pressing roller172, respectively).

In this embodiment, the mechanisms are controlled by the CPU301. Alternatively, however, the use can be made with CPU circuit portions for controlling the respective mechanisms and a main CPU circuit portion connected with the respective CPU circuit portions to effect the overall control.

The image forming apparatus400comprises stations120,121,122and123as the image forming station309(FIG. 23), an intermediary transfer belt115as an intermediary transfer member, and a transfer roller116as a transfer portion. The image forming stations are the same as those of Embodiment 1, and therefore, in the description of this embodiment, the same reference numerals as in Embodiment 1 are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

The first fixing device150and the second fixing device170as the fixing portion fix the toner image transferred onto the recording material102by applying heat and pressure to the recording material102.

The second fixing device170is disposed downstream of the first fixing device150with respect to the feeding direction of the recording material102. The second fixing device170functions to provide the toner image fixed on the recording material102by the first fixing device150with glossiness and/or to supplement the heat quantity for a large basis weight recording material (thick sheet, for example) which requires a large amount of heat for the fixing operation.

On the other hand, in the case that the heat by the first fixing device150is enough to fix the image, it is unnecessary to use the second fixing device170, and therefore, the recording material102is fed into the feeding path130, bypassing the second fixing device170, for the purpose of saving the energy consumption. For example, this occurs in the case that the recording material102is plain paper or thin sheet, and high glossiness is not desired. As to whether to feed the recording material102into the second fixing device170or to feed the recording material102so as to bypass the second fixing device170(bypass route), the CPU301controls such an operation by switching the flapper131.

(29.2. Structure of Fixing Device)

The first fixing device150and the second fixing device170are detachably mountable to the first mounting portion141and the second mounting portion142(collectively, mounting portion) of the image forming apparatus400, respectively. The first fixing device150and a second fixing device170can be replaced with the fixing devices having the following structures, respectively.

The first fixing device150is provided with a memory154as a storing portion of the fixing device (fixing device storing portion). The second fixing device170is provided with a memory174as a storing portion of the fixing device (fixing device storing portion). The details will be described hereinafter.

The first fixing device150is provided with sensors153and155as a jam detecting portion, and the second fixing device170is provided with sensors173and175as a jam detecting portion. The details will be described hereinafter. For the respective fixing devices, the upstream sensors155,175with respect to the feeding direction of the recording material102also function as detecting portions for detecting the feeding of the recording material102to the respective fixing devices. The details will be described hereinafter.

FIG. 3is a sectional view of an example of a fixing portion.

In the description of this embodiment, the same reference numerals as in the foregoing embodiments are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

The following description will be made with respect to the first fixing device150, but the same applies to the second fixing device170unless otherwise described (i.e., the structures of the first fixing device150apply to the structures of the second fixing device170).

In this embodiment, the structures of the pressing sides of the first fixing device150and the second fixing device170are different, but they may be the same More particularly, the pressing side structures of the first fixing device150and the second fixing device170may use pressing belts or pressing rollers Alternatively, the pressing side may comprise the pressing roller in the first fixing device150, and the pressing side may comprise a pressing belt in the second fixing device170.

As to the refreshing roller156as the rubbing rotatable member for effecting the rubbing treatment to the surface of the rotatable member, the description thereof in Embodiment 1 applies, and therefore, the detailed description is omitted for simplicity (see 4. 3. Refreshing roller).

(30. Glossiness Unevenness at the Widthwise End Portion of the Recording Material)

The reason for the necessity of the fixing element refreshing operation has been described with respect to Embodiment 1, and therefore, the description thereof is omitted (see 5. Glossiness unevenness produced by end portions of the recording material).

As described in the foregoing, when the recording materials102pass through the nip repeatedly, the unevenness of the surface state is produced in the longitudinal direction of the fixing roller151(the direction of the rotational axis).

In view of this, in the image forming apparatus400, after a predetermined number of recording materials102are fed into the first fixing device150, the fixing element refreshing operation for improving the surface state of the fixing roller151is carried out. The fixing element refreshing operation is the same as that of Embodiment 1, and therefore, the description thereof is omitted (see 6. Fixing roller refreshing operation; 6. 1. Recording material counting method; 6. 2. Fixing roller refreshing operation). In the fixing element refreshing operation, the time period (30 sec in this embodiment) of the rubbing treatment of the refreshing roller156is counted by the timer307provided in the image forming apparatus400. The time counting may be accomplished by a clock provided in the image forming apparatus400counting the time on the basis of the clock time outputted by the CPU301.

(32. Effects of the Fixing Element Refreshing Operation)

The effects of the fixing element refreshing operation has been described in conjunction with Embodiment 1, and therefore, the description is omitted (see 7. Effects of fixing element refreshing operation).

The stand-by mode means the state in which the image forming apparatus400is in the state capable of starting of the image forming operation and waits for the printing instructions (printing job) by the operator. The operating portion180receives the printing job including the kind of the recording material102(surface property, basis weight, size or the like) on which the image is to be formed, the number of prints, and one-side printing/both side printing. The details thereof are the same as with Embodiment 1, and therefore, the description thereof is omitted (see 8. Stand-by mode) (the image forming apparatus100of the foregoing embodiments should read image forming apparatus400).

The fixing device is an exchangeable system of this embodiment, and is the same as that of Embodiment 1, and therefore, the description thereof is omitted for simplicity (see 9. Fixing device exchanging system).

(35. Fixing Device Memory and Main Assembly Memory)

In this embodiment, the fixing device is exchangeable, and the first fixing device150is provided with a storing portion (fixing storing portion) and a memory154as a discrimination portion. Similarly, the second fixing device170is provided with a storing portion (fixing storing portion) and a memory174as a discrimination portion. The memories154,174are rewritable non-volatile memories such as a flash memory. A memory is also provided on a fixing device (not the first fixing device150or the second fixing device170already mounted in the image forming apparatus400) kept outside of the image forming apparatus400.

These memories (memory154, memory174, and the memory provided on the replacement fixing device) store identifying information for discriminating between them, and function as discrimination portions. In the following, the identifying information stored in the memory154of the first fixing device150is called an ID of first fixing device150(fixing device).

The fixing device group, including the first fixing device150and the second fixing device170, is provided with the memory in order to solve the problem described below.

In addition, the image forming apparatus400is provided with a main assembly memory312as a storing portion. The main assembly memory312is a rewritable non-volatile memory, such as an EEPROM, flash memory or the like. However, it may be integral with RAM302if it is rewritable and non-volatile.

The fixing device group, including the first fixing device150and the second fixing device170, is provided with the memory in order to solve the problem described below. The problem arises when the first and/or second fixing device is once taken out of the apparatus400, and then the fixing device is remounted in the image forming apparatus400. The following description will be made taking the first fixing device150as an example, but the same applies to the second fixing device150. The following description is applied also to the second fixing device170.

More particularly, the following two situations may occur. That is, the fixing device to be replaced is the first fixing device150.

A first situation (situation 1) will be described.

For example, the first fixing device150carries out the fixing element refreshing operation after 500 recording materials102are processed (after the feeding number becomes 500). That is, the predetermined number is 500. In the case that the fixing device A not exclusively for envelopes is mounted in the main assembly400A of the image forming apparatus400as the first fixing device150, a printing job of 450 sheets (on A4 size plain paper longitudinally fed, for example) is carried out. Thereafter, the operator is required to print on envelopes, and then the operator removes the fixing device A from the image forming apparatus400to mount the fixing device B exclusively for envelopes. The operator carries out the printing job including 50 envelopes with the fixing device B mounted as the first fixing device150.

The CPU301counts the feeding number of the recording materials into the first fixing device by the counter provided in the main assembly of the image forming apparatus, and the fixing element refreshing operation is executed after the feeding number exceeds the predetermined number. That is, the CPU301executes the fixing element refreshing operation after the feeding number exceeds in the predetermined number, irrespective of whether the fixing device mounted as the first fixing device is the fixing device A or the fixing device B. Therefore, when the fixing device is switched from the fixing device A to the fixing device B, the CPU301discriminates that the feeding number of the first fixing device exceeds 500 when the 50 sheets are processed by the fixing device B, and carries out the fixing element refreshing operation for the fixing device B only. Then, the CPU301discriminates that the fixing element refreshing operation after the 500 sheets feeding has been completed.

Some days later, when the operator is going to print on the recording material102(plain paper, for example) other than the envelope, the operator changes the fixing device by remounting the fixing device A. The operator then executes 50 sheets printing job (on A4 size plain paper longitudinally fed, for example).

The fixing device A has already processed 450 sheets in the previous operation, and therefore, the uneven surface state of the fixing roller arises with respect to the longitudinal direction arises upon only 50 sheets being processed. If the next printing job is carried out (on A4 size plain paper longitudinally fed, for example), the glossiness unevenness occurs on the outputted image, that is, the image quality is significantly deteriorated.

As for a method for solving the problem arising in situation 1, the memory312provided in the main assembly400A of the image forming apparatus400stores the feeding number information for each ID of the fixing device, as described in Embodiment 12, for example (this method is method 1). Using method 1 in the situation 1, the memory312of the main assembly400A of the image forming apparatus400can store the feeding number on the fixing device A. As a result, for the fixing device A which was taken out of the apparatus400after 450 recording materials102are processed, and then was remounted in the apparatus400, and thereafter processed 50 recording materials102, the fixing element refreshing operation can be carried out. Therefore, the deterioration of the image quality can be suppressed even when the fixing portion is replaceable.

According to this embodiment, the deterioration of the image quality of the output portion can be suppressed even in another situation (situation 2). In the case that the user uses a plurality of image forming apparatuses, the fixing device which has been operated in one image forming apparatus400may be mounted in another image forming apparatus400.

The fixing device A is usable with anyone of the image forming apparatuses400(image forming apparatuses P, Q) as the first fixing device150. That is, the fixing device to be replaced is the first fixing device150.

Suppose the fixing device A has processed 40 recording materials in the image forming apparatus P (image formation on A4 size plain paper sheets).

On the next day, the operator takes the very fixing device A from the image forming apparatus P and remounts it in the image forming apparatus Q. Then, the operator uses the fixing device A as the first fixing device150of the image forming apparatus Q to execute a printing job of 400 sheets (image formation on A4 size plain paper sheets). In such a case, the fixing device A has processed 440 recording materials.

Thereafter, the operator takes the fixing device A, having processed 440 recording materials, and remounts it in the image forming apparatus P, and 60 recording materials are processed by the image forming apparatus P using the first fixing device150which is the fixing device A (image formation on A4 size plain paper sheets).

If the above-described method 1 is used, the memory312of the main assembly of the image forming apparatus P stores the information indicating that the fixing device A has processed 40 recording materials. However, the fixing device A remounted in the image forming apparatus P has processed 440 recording materials, including the amount processed in the image forming apparatus Q.

When the fixing device A processes 60 recording materials after being remounted in the image forming apparatus P, the fixing roller has an uneven surface state in the longitudinal direction. However, with the above-described method 1, the memory312of the main assembly of the image forming apparatus P stores the information indicating that the fixing device A has processed 100 recording materials in total. If the next printing job is carried out in this state (image formation on A3 plain paper sheets, for example), the glossiness unevenness arises on the outputted image. It is desirable that the fixing element refreshing operation is carried out for the fixing device A in such a case, too.

Under the circumstances, in this embodiment, the first fixing device150is provided with a memory154as a fixing storing portion capable of storing the information. The CPU301stores the information indicative of the number of the recording materials102fed to the first fixing device150(number information) in both of the memory154and the main assembly memory312.

The memory154of the first fixing device150stores the number information and the information (time information) indicative of the time and day at which the number information is recorded in the memory154. The memory154stores the ID of the fixing device (fixing device A, for example) as the identifying information for discriminating the fixing device A from the other fixing devices, and therefore, the memory154functions as the discrimination portion.

On the other hand, the image forming apparatus400is provided with the main assembly memory312as the main assembly storing portion capable of storing the information. The CPU301stores, in the main assembly memory312, the number information which is the same as in the recording in the memory154, the information indicative of the time and day at which the number information is recorded in the memory154, the ID of the fixing device mounted as the first fixing device150.

Part (a) ofFIG. 28shows an example of the information stored in the main assembly memory312, and (b) shows a example of the information stored in the memory154of the fixing device.

The information of the time and day is used to discriminate which of the number information stored in the memory154and the number information stored in the main assembly memory312is it to be used. The CPU301, as the counter, counts the number of the recording materials102(feeding number) fed to the first fixing device150on the basis of later number information of the information stored in the main assembly memory312and the information stored in the memory154.

(35.2. Count on the Basis of the Information Stored in the Main Assembly Memory)

The CPU301counts the recording materials on the basis of the later pieces of the information stored in the main assembly memory312and the memory154. By this, the fixing element refreshing operation can be executed for the first fixing device150on the basis of the more accurate number information. Therefore, the deterioration of the image quality on the output recording material102can be deteriorated.

The structure of this embodiment will be described in more detail.

In response to the remounting of the first fixing device150by the operator, the CPU301acquires the ID of the fixing device and the time and day information from the first fixing device150. The mounting of the first fixing device150will be described hereinafter. The CPU301acquires from the main assembly memory312the time and day information corresponding to the ID of the fixing device acquired from the first fixing device150. The CPU301compares the day and time stored in the memory154of the first fixing device150mounted in the image forming apparatus400and the time and day stored in the main assembly memory312, and discriminates which is later.

The CPU301counts the recording materials102fed to the first fixing device150on the basis of the number information acquired from the later information.

Then, if the number information of the later information exceeds the predetermined number, the CPU301executes the refresh operation. If, on the other hand, the later number information does not exceed the predetermined number, the CPU301increases the count of the recording materials from the later number on the main assembly memory312. For example, if the later one of the numbers in the main assembly memory312and the memory154is 30, the CPU301counts the recording materials102fed to the first fixing device150, increasing the count to 31, 32, 33, and so on, on the main assembly memory312. If the count on the main assembly memory312exceeds the predetermined number, the CPU301executes the fixing element refreshing operation. In this embodiment, the feeding of the recording material102into the first fixing device150is detected by the sensor155. After the execution of the fixing element refreshing operation, the CPU301resets the count on the main assembly memory312.

The count per one sheet may be weighted depending on the length of the recording material102measured in the feeding direction. That is, the values stored in the main assembly memory312and/or the memory154and counted on the main assembly memory312as the reference for the execution of the fixing element refreshing operation may be the ones corresponding to the feeding number of the recording materials102fed to the first fixing device150. In this case, similarly to the main scan direction length information of the recording material102, the length of the recording materials102in the feeding direction is acquired from the content of the printing job received by the CPU301. The degree of the weighting is prestored in the ROM303and is acquired by the CPU301.

The method for counting the feeding number on the basis of the information in the main assembly memory312and/or the memory154is not limited to that described above.

For example, the CPU301may count up the recording materials102fed into the first fixing device150on the memory154for each feeding thereof into the first fixing device150. The CPU301counts the recording materials on the basis of the later one of the information of the information stored in the main assembly memory312and the information stored in the memory154. Therefore, also in this case, the CPU301, as the counter, counts the recording materials102fed to the first fixing device150on the basis of the main assembly memory312and the information in the memory154of the first fixing device150mounted in the main assembly.

The CPU301may count the recording materials102fed into the first fixing device150on the RAM302for each feeding into the first fixing device150. The CPU301counts the recording materials on the basis of the later one of the information stored in the main assembly memory312and the information stored in the memory154.

The CPU301may count the later feeding number plus the feeding number acquired from the memory154up to the predetermined number. More particularly, when the acquired later information is 30, the CPU301increments by one on the RAM302for each feeding of the recording material102into the first fixing device150on the main assembly memory312. Assuming that the predetermined number is 500, the CPU301discriminates exceeding of the predetermined number when the count on the main assembly memory312reaches 470.

The reference on which the fixing element refreshing operation is executed may not be the number of the sheets of the recording material102fed into the first fixing device150. For example, it may be a total of the lengths of the recording materials102in the feeding direction fed into the first fixing device150. In this case, the memory154of the first fixing device150stores in the length information indicative of the length of the recording materials102fed to the first fixing device150in the feeding direction, the time and day information at which the length information is stored in the memory154, and the identifying information in the discrimination portion. On the other hand, the main assembly memory312stores the length information which is the same as in the information stored in the memory154, and the time and day information at which the length information is recorded in the memory154in correlation with the ID of the fixing device as the first fixing device150. The CPU301adds (counts) the lengths of the recording materials102fed to the first fixing device150in feeding direction to the later length information. When the value exceeds the predetermined length, the CPU301executes the fixing element refreshing operation.

As the reference for executing the fixing element refreshing operation, the time period in which the fixing roller151carries out the fixing process may be used, for example. In such a case, the memory154of the first fixing device150stores the time period information in which the fixing roller151carries out the fixing process, the time and day information at which the time and day is recorded in the memory154, and the identifying information in the discrimination portion. On the other hand, the main assembly memory312stores the time period information which is the same as in the information recorded in the memory154, and the time and day information at which the time period information is recorded in the memory154in correlation with the ID of the fixing device as the first fixing device150. The reference for the execution of the fixing element refreshing operation is a period of time (4000 sec, for example). More particularly, the timer (clock portion)307counts the time period in which the fixing roller151and the pressing belt152contact with each other. The CPU301sets the time of the time period information corresponding to the later time and day as the initial value of the timer307. The timer307counts the time period in which the fixing roller151is in contact with the pressing belt152, continuing from the set initial value. When the value of the timer307exceeds the predetermined time period, the CPU301executes the fixing element refreshing operation. Alternatively, the initial value of the timer307may be zero, in which the CPU301adds the time counted by the timer307to the time discriminated as later data, so that the total image fixing period of the fixing roller151is obtained.

Also when no information of the feeding number is stored in the main assembly memory312and/or the memory154(zero), the CPU301deems the information of the feeding number stored.

The main assembly memory312and/or the memory154may store the information other than the feeding number information. For example, the information indicative of the usage of a kind of the recording material processed by the first fixing device150, such as an envelope or an A4 the size may be stored. In addition, in the case that the fixing device mountable to the first mounting portion141and the fixing device mountable to the second mounting portion142are different from each other, the information indicative of whether the fixing device is mountable to the first mounting portion141or to the second mounting portion142may be stored.

Furthermore, the main assembly memory312may store the information for a plurality of fixing devices.

(35.3. Mounting of Fixing Device)

The mounting of the first fixing device150will be described.

When the first fixing device150is to be exchanged, the operator opens the front door140, and draws the first fixing device150out of the image forming apparatus100and then exchanges the fixing device. Then, the first fixing device150is moved in the opposite direction to set it in the image forming apparatus400, and the front door140is closed.

The CPU301detects that the front door140is closed, on the basis of the signal from the opening and closing sensor305. Upon the detection of the closure of the front door140, the CPU301accesses the memory154of the first fixing device150. By this, it is confirmed that the first fixing device150is mounted. If the CPU301is unable to access the memory154, the CPU301discriminates that the first fixing device150is not mounted.

If the fixing device is exchanged in the OFF-state of the main switch101, the opening and closing sensor305is unable to detect in the closure of the front door140. Therefore, the CPU301accesses the memory154of the first fixing device150in response to the actuation of the main switch101. By this, it is confirmed that the first fixing device150is mounted. If the CPU301is unable to access the memory154, the CPU301discriminates that the first fixing device150is not mounted.

The method for discriminating whether or not the first fixing device150is mounted is not limited to that described above, and may be discriminated by electrical conduction or non-conduction state between the image forming apparatus100and the first fixing device150, for example.

More particularly, the image forming apparatus400is provided with an ammeter, and the CPU301monitors an output of the ammeter, so that it can detect that the electric current flows. When the first fixing device150is mounted in the image forming apparatus400, the ammeter and the first fixing device150are electrically connected with each other. By this, the ammeter is capable of detecting the current flowing to the first fixing device150when the first fixing device150is supplied with a predetermined voltage. If the ammeter detects the electric current upon the application of the predetermined voltages to the first fixing device150, it means that the image forming apparatus400and the first fixing device150are electrically connected with each other, and therefore, the CPU301discriminates that the first fixing device150is mounted. On the hand, if the ammeter does not detect the current application of the predetermined voltage to the first fixing device150, the first fixing device150is not electrically connected with the image forming apparatus400, and therefore, the CPU301discriminates that the first fixing device150is not mounted.

(35.4. Count for Each Width Size)

Furthermore, in this embodiment, the feeding number is stored for each widthwise size of the recording material102, and the feeding numbers for the respective widthwise sizes are stored in the main assembly memory312and/or the memory154. The widthwise size measured in the direction perpendicular to the feeding direction of the recording material102is called the main scan direction length (or width size).FIG. 28shows an example in which the feeding numbers are stored for each 5 mm main scan direction length of the recording material102.

As described hereinbefore, the roughened area in the (III) boundary area is produced by the edge portions of the recording materials102repeatedly contacting the same position of the fixing roller151with respect to the direction of the rotational axis of the fixing roller151. That is, the roughened area is produced with the increase of the feeding number of the recording materials102.

By the fixing element refreshing operation, the surface state of the fixing roller151is uniformized in the entirety of the longitudinal range (i.e., the (I) non-passing portion, the (II) passing portion, and the (III) boundary area). Therefore, the unevennesses of the surface state of the fixing roller151produced by the edge portions of the recording materials102having different main scan direction lengths is also eliminated.

Therefore, in this embodiment, the number of the recording materials102fed into the first fixing device150is stored for each 5 mm of the main scan direction length of the recording material102, in the main assembly memory312and the memory154. When the feeding number for any one of the main scan direction lengths exceeds the predetermined number (500, in this example), the CPU301executes the fixing element refreshing operation. Thereafter, the feeding numbers for all of the main scan direction lengths are reset (zero). When the feeding number for any one of the main-scanning lengths exceeds the predetermined number, the CPU301executes the fixing element refreshing operation.

The information of the main scan direction length of the recording material102is acquired from the content of the printing job received by the CPU301. When the operating portion180receives the printing job from the operator, it also receives the size of the recording material102(A3, for example) on which the image is to be formed, as one of the contents of the printing job. Thus, the operating portion180functions as the receiving portion.

By this, the glossiness unevenness on the output images can be suppressed, and also, the frequency of the fixing element refreshing operations is made lower than when the fixing element refreshing operation is carried out the irrespective of the main scan direction length of the recording material102.

In Embodiment 13, the CPU301counts the feeding number of the recording materials102to the first fixing device150, on the main assembly memory312, for each main scan direction length (each width size). The CPU301renews and records the count of the feeding number corresponding to the ID of the writing portion on the main assembly memory312, for each feeding of the recording material102to the first fixing device150on the basis of the signal from the sensor155. In this manner, the CPU301functions as a counter.

When the count of the recording material102for any one of the main scan direction lengths exceeds the predetermined value during the printing operation, the fixing element refreshing operation is carried out after completion of the currently executing printing job, and then the apparatus shifts into the stand-by mode. That is, if the count at the time of the completion of the image forming operation exceeds the predetermined value, the fixing element refreshing operation is executed after the completion of the current printing job.

The CPU301stores the number information and the time and day information in the main assembly memory312and the memory154.

Upon the actuation of the main switch101and the closure of the front door140, the CPU301acquires the ID of the first fixing device150and the time information from the memory154. The CPU301executes the fixing element refreshing operation if the later one of the pieces of the information, for any one of the main scan direction lengths, stored in the main assembly memory312and the memory154as the feeding number information for the first fixing device150exceeds the predetermined value. Thereafter, the apparatus shifts to the stand-by mode.

The description will be made in conjunction with the flow charts ofFIGS. 24-27.

The operations of the flow charts are carried out by the CPU301functioning as the executing portion (recording portion) controlling the related mechanisms of the image forming apparatus400in accordance with the control program stored in the ROM303. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

(36.1. Sequence Upon Actuation of the Main Switch and Upon Closing the Front Door)

FIG. 24is a flow chart showing the operations from the actuation of a main switch101to a stand-by mode.

With the actuation of the main switch101, the CPU301starts. The CPU301discriminates whether or not the first fixing device150is mounted in the image forming apparatus400(S2101). If the first fixing device150is mounted on the apparatus400, the CPU301can detect the ID of the fixing device. If the result of the discrimination at step S101is negative, the operation returns to step S101. In such a case, the CPU301may display a message prompting the insertion of the first fixing device150, on the operating portion180. If the first fixing device150is mounted in the image forming apparatus400, the operation proceeds to step S2102.

The CPU301carries out the refreshing sequence shown inFIG. 26for the first fixing device150(S2102). The details of the operation will be described hereinafter.

In step S2103, the CPU301waits for the image forming apparatus400to become capable of carrying out the image. The CPU301carries out the preparing operation (starting-up operation) for the start of the image forming operation for various mechanisms such as the first fixing device150and the image forming stations309, after the actuation of the main switch101. The temperature control for the fixing roller151is one of them, for example.

When the image forming apparatus400becomes capable of carrying out the image forming operation after the completion of the starting-up operations (Yes, S2103), the CPU301displays “printable” or the like on the operating portion180(S2104). By this, the operator is notified of the fact that the image forming apparatus400has become capable of carrying out the image forming operation. The apparatus400is shifted into the stand-by mode.

FIG. 25is a flow chart showing the operations from the state in which a front door is open to the stand-by mode.

The opened and closed states of the front door140are detected by the CPU301on the basis of the signal from the opening and closing sensor305of the front door140. When the front door140is open, the CPU301waits for the closing of the front door140(S2201). When the front door140is open, the CPU301may display information to prompt to close the front door140. When the CPU301detects the closing of the front door140(S2201), the operation proceeds to step S2202. Steps S2202-S2205are the same as steps S2101-S2104ofFIG. 24, and therefore, the description thereof is omitted. After step S2205, the operation proceeds to the stand-by mode.

FIG. 26is a flow chart of a refreshing sequence. The flow chart ofFIG. 26shows steps S2102and S2203, and the details of the refreshing sequence, which will be described hereinafter.

First, the CPU301reads out the data stored in the memory154of the first fixing device150mounted in the image forming apparatus400(S2301).

The CPU301reads the data out of the main assembly memory312(S2302).

In step S2303, the CPU301discriminates whether or not the main assembly memory312stores the information of the ID of the first fixing device150. More particularly, the CPU301searches the data for the ID of the first fixing device150read out in step S2301in the main assembly memory312.

If any data for the ID of the first fixing device150read out in step S2301is stored in the main assembly memory312(S2303, Yes), the CPU301proceeds to step S2304.

If, on the other hand, the main assembly memory312does not store the data for the ID of the first fixing device150read out in step S2301(S2303, No), the CPU301proceeds to step S2305. In this case, the main assembly memory312does not store the number information for the first fixing device150mounted in the image forming apparatus400.

If the result of discrimination in step S2303is Yes, the CPU301discriminates which one of the number information of the memory154and the number information of the main assembly memory312is to be used (S2304). More particularly, the CPU301checks which one of the recording time of the information stored in the memory154and the information stored in the main assembly memory312is later.

If the time of the information record of the memory154is later than that of the main assembly memory312(S2304, Yes), the CPU301proceeds to step S2305.

On the other hand, if the information regarding time of the memory154is later than that stored in the main assembly memory312corresponding to the ID of the first fixing device150(S2304, No), the CPU301proceeds to step S2306. When they are the same, the CPU301proceeds to step S2306(S2304, No).

If the result of discrimination in step S2304is negative, the CPU301counts the recording materials on the basis of the number information of the main assembly memory312. If, in step S2306, the number information of the main assembly memory312for the ID of the first fixing device150is not more than the predetermined number (500in this example) for any of the feeding numbers for the main scan direction lengths, the CPU301proceeds to step S2309. In this case, the main assembly memory312already stores the feeding number to be set for the counter.

On the other hand, if, in step S2306, the number information of the main assembly memory312for the ID of the first fixing device150exceeds the predetermined number (500in this example) for any one of the feeding numbers for the main scan direction lengths, the CPU301proceeds to step S2307.

In step S2307, the CPU301executes the above-described fixing element refreshing operation. By this, the surface of the fixing roller151is rubbed, so that the surface state is made even.

After the completion of the fixing element refreshing operation, the CPU301sets the counts for the respective main scan direction lengths to zero. That is, the counts in the main assembly memory312are reset (S2308). By this, when the feeding number for any one of the main-scanning lengths exceeds again the predetermined number after the execution of the fixing element refreshing operation, the CPU301can execute the fixing element refreshing operation. The CPU (recording portion, writing portion)301makes the records in correlation with the ID of the first fixing device150. By this, the information indicative of the execution of the fixing element refreshing operation is recorded in the main assembly memory312in correlation with the ID of the first fixing device150.

On the other hand, if the result of discrimination in S2303is negative, or if the result of discrimination in S2304is affirmative, the CPU301counts the recording material on the basis of the number information of the memory154of the first fixing device150. If, in step S2305, the feeding number (count) for any one of the main scan direction lengths stored in the memory154exceeds the predetermined value, the CPU301proceeds to step S2307to execute the fixing element refreshing operation. If, on the other hand, the feeding number (count) for any one of the main scan direction lengths stored in the memory154is not more than the predetermined value (500 in this example), the CPU301proceeds to step S2311.

In step S2311, the CPU301sets the feeding number for each main scan direction length on the memory154in the main assembly memory312as the count of the counter. That is, the counter is reset. The CPU (recording portion, writing portion)301makes and records the feeding number in correlation with the ID of the first fixing device150. By this, the feeding number information can be recorded in the main assembly memory312in correlation with the ID of the first fixing device150.

In step S2309, the CPU (recording portion, writing portion)301records the feeding number information in the memory154. More particularly, the CPU301copies the counts set in the main assembly memory312in steps S2308and S2311in the memory154, for each main scan direction length. In the case that the operation has proceeded through step S2308, for example, the feeding numbers for all the main scan direction lengths are set to zero in the memory154.

In step S2310, the CPU301records the time and day information in the memory154and the main assembly memory312. In the main assembly memory312, the record is made in correlation with the ID of the first fixing device150. In this embodiment, the time and day information is that at the completion of the process of step S2309.

The reading of the memory154in step S2301and the reading of the main assembly memory312in step S2302may be carried out in a plurality of steps. For example, the CPU301may fetch the necessary information from the memory154and/or main assembly memory312for each process of steps S2303, S2304, S2305, and S2306.

In steps S2308and S2311, if the main assembly memory312does not store the information of the ID of the first fixing device150(No, in step S2303), the CPU301records the ID of the first fixing device150. In steps S2308and S2311, the CPU301stores the counts for the respective main scan direction lengths in correlation with the ID of the first fixing device150in the main assembly memory312as the count of the counter.

If the feeding number information in the memory154and the feeding number information to be written in the memory154in step S2309are the same (No, in step S2305, for example) the CPU301may not change the data in step S2309.

The time and day recorded in step S2310is not limited to that at the completion of the process of step S2309. For example, the time and day recorded in step S2310may be the time and day of the completion of steps S2308and/or S2311, or the time and day of the start of the process of step S2309.

The order of the operation of storing the number information, the time and day and the ID of the first fixing device150in the main assembly memory312, and the operation of storing the number information and the time and day in the memory154is not limited to the order of steps S2308, S2309, and S2310. For example, as an alternative, the feeding number in the memory154is first made zero, and is stored as the time and day in the memory154. Then, these two pieces of information may be copied from the memory154to the area in the main assembly memory312corresponding to the ID of the first fixing device150, by which the counter is reset. In addition, steps S2308and S2309may be executed simultaneously, for example.

Further alternatively, the processes of steps S2309and S2310may be carried out in response to the detection of the opening of the front door140on the basis of the signal from the opening and closing sensor305. In addition, the processes of steps S2309and S2310may be carried out in response to the deactuation of the main switch101. This is because the exchange of the first fixing device150necessitates the opening of the front door140.

In this embodiment, when the time and day information stored in the memory154and the time and day information stored in the main assembly memory312in correlation with the ID of the first fixing device150are the same, the CPU301effects the control on the basis of the feeding number information of the main assembly memory312. In such a case, however, the CPU301may fix the control on the basis of the number information of the memory154. In this case, when the time and day information stored in the memory154and the time and day information stored in the main assembly memory312in correlation with the ID of the first fixing device150are the same in step S2304, the CPU301proceeds to step S2305.

(36.3. Sequence for Recording Material Counting)

FIG. 27is a flow chart of counting of the recording materials. More particularly, it is a flow chart of printing job execution by the image forming apparatus400.

In the stand-by mode in which the image forming apparatus400is capable of carrying out the printing operation, it waits for the printing job from the operating portion180or an external PC or the like through the outside I/F portion304(S2401). At this time, the image forming apparatus400displays a selection screen for selecting the kind of the recording material102on the operating portion180or a display screen of the external PC and receives the kind of the recording material102to be used for the printing by the operator as a content of the printing job.

When the printing job is received (Yes, S2401), the CPU301controls the mechanisms such as the stations120-123, the first fixing device150, the second fixing device170, or the like, of the image forming apparatus400, and starts the image forming process operation of the image forming apparatus400. In other words, the printing job is started (S2402).

If the CPU301detects the feeding of the recording material102to the first fixing device150(S2404, Yes) in the stage in which the printing job is not completed (in S2403, No), the CPU301increments the count on the main assembly memory312. The CPU301increments the count corresponding to the main scan direction length of the fed recording material102for the ID of the first fixing device150, of the counts on the main assembly memory312. The information of the main scan direction length of the fed recording material102is acquired by the CPU301on the basis of the content of the printing job in step S2401. The CPU301detects the feeding of the recording material102to the first fixing device150depending on the signal from the sensor155.

On the other hand, if the feeding of the recording material102to the first fixing device150is not detected in step S2404, the CPU301does not increment the count, and proceeds to step S2406. This occurs, for example, in the case that after the detection of the passage of the recording material102, the passage of the next recording material102is not detected after elapse of predetermined time, despite the non-completion of the printing job. The predetermined time period is counted by the timer307.

When no sheet jamming in the image forming apparatus400is detected (S2406, No), the CPU301continuous the operation for the printing job until the completion of the printing job, while repeating the operations of steps S2404and S2405.

When the CPU301(recording portion, writing portion) detects the jamming in the image forming apparatus400(S2406), the CPU301records the count on the main assembly memory312for the main scan direction length in the memory154as the information of the feeding number (S2407). The CPU301detects the jamming in the image forming apparatus400on the basis of the signals from the sensor group306. For example, in the case that, upon elapse of a predetermined time from the detection of the recording material102by the sensor disposed in the upstream side with respect to the feeding direction of the recording material102, the sensor disposed in the downstream side does not detect the passage of the recording material102, the CPU301discriminates that the recording material102stagnates in the portion between the two sensors. The predetermined time is counted by the timer307.

In addition, the CPU (recording portion, writing portion)301stores the time and day information in the memory154and the main assembly memory312(S2408). In the main assembly memory312, the record is made in correlation with the ID of the first fixing device150. In this embodiment, the time and day information is that at the completion of the process of step S2407.

When the jamming occurs in the image forming apparatus400, the CPU301interrupts the printing job. At this time, the jammed recording material stagnating in the feeding path of the image forming apparatus400is cleared by the operator, and therefore, the front door140or the like is opened.

The CPU301waits for the front door140to close (S2409). When the CPU301detects the closing of the front door140on the basis of the signal from the opening and closing sensor305(S2409), the refreshing sequence is carried out (S2410).

The refreshing sequence in step S2410corresponds to the flow shown inFIG. 26. In the refreshing sequence, the data in the memory154in the first fixing device150is read out as described in the foregoing (S2301). The memory154is read out because there is a possibility that the first fixing device150is exchanged when the front door140is opened for the jam clearance.

In step S2411, the CPU301waits for the image forming apparatus400to become capable of carrying out the image forming operation. The CPU301carries out the preparing operation (starting-up operations) for resuming the image forming operation for various mechanisms such as the first fixing device150, the image forming station309and the like of the image forming apparatus400after the clearance of the jammed recording material. The temperature control for the fixing roller151is one of them, for example.

When the image forming apparatus400becomes capable of resuming the image forming operation after the completion of the starting-up operations (Yes, S2411), the CPU301displays “printable” or the like on the operating portion180(S2412). By this, the operator is notified of the fact that the image forming apparatus400has become capable of carrying out the image forming operation. Thereafter, the operation returns to step S2403, and the CPU301resumes the operations for the remaining printing job and continues up to the completion of the printing job.

When the printing job is completed (S2403, Yes), the CPU301discriminates whether or not any one of the feeding numbers for all the main scan direction lengths correlated with the ID of the first fixing device150on the main assembly memory312exceeds the predetermined value (500 in this example) (S2413).

If the result of the discrimination is negative, that is, if the values of the feeding numbers for all of the main scan direction lengths stored in the main assembly memory312are less than the predetermined value (500 in this example), the CPU301proceeds to step S2416.

If the result of the discrimination is affirmative, that is, if a value of the feeding number for any one of the main scan direction lengths exceeds the predetermined value (500 in this example), the CPU301executes the fixing element refreshing operation (S2414). After the completion of the fixing element refreshing operation, the CPU301resets the values for all of the main scan direction lengths on the main assembly memory312to zero. That is, the counter values are reset (S2415).

In step S2416, the CPU301records the count of the main assembly memory312for each main scan direction length as the information of the feeding number. As the operation has proceeded through the flow of step S2415, the feeding numbers for all the main scan direction lengths as the information of the feeding number become zero.

In addition, the CPU (recording portion, writing portion)301stores the time and day information in the memory154and the main assembly memory312(S2417). In the main assembly memory312, the record is made in correlation with the ID of the first fixing device150. In this embodiment, the time and day information is that at the completion of the process of step S2416.

The CPU301displays “printable” on the operating portion180to notify of the operativity of the image forming apparatus400(S2418). The apparatus is shifted into the stand-by mode.

The information of the feeding number is stored in the memory154before entering the stand-by mode. By this, a correct feeding number can be stored in the memory154even when the first fixing device150is removed from the image forming apparatus400during the stand-by mode.

The writing in the memory154in step S2407may be effected only when the jamming occurs in first fixing device150and/or the second fixing device170in step S2406. It is expected for the front door140to be opened by the operator after the occurrence of the jamming because the jamming occurs in the fixing portion. This is because in the case of the jamming in the fixing portion, the operator clears the recording material102stagnating in the first fixing device150and/or the second fixing device170. The liability that the first fixing device150is exchanged by the operator arises when the front door140is opened.

In such a case, the sensors153,155function as the jam detecting portion. The sensors may be an optical sensor, for example. The CPU301receives the signals from the sensors153and/or155to detect the stagnation of the recording material102in the first fixing device150(jamming in the fixing portion). For example, in the case that after the elapse of the predetermined period after the passage of the recording material102by the sensor155disposed at an upstream side with respect to the feeding direction of the recording material102, the downstream side sensor153does not detect the passage of the recording material102, the CPU301discriminates that the recording material102stagnates between the sensors155and153. The predetermined time is counted by the timer307.

In the fixing element refreshing operation in step S2307(FIG. 26), and step S2414(FIG. 27), the duration of the rubbing treatment by the refreshing roller156may not be constant. That is, the CPU301carries out the rubbing treatment for a time period corresponding to the amount, beyond the predetermined count (500in this example), of the count (excess amount) of the feeding number for the main scan direction length.

For example, for the predetermined value of 500, when the count is 500 in step2413, the rubbing treatment duration in step S2414is 30 sec, and when the count is 600 in step S2413, the rubbing treatment duration in step S2414is 40 sec.

In this case, the duration of the rubbing treatment may be gradually or stepwisely increased with the increase of the exceeding amount of the count. The data (table, function or the like) for providing the correspondence between the exceeding amount of the count relative to the predetermined value and the rubbing treatment duration is stored in the ROM303beforehand.

As described hereinbefore, the exchange of the first fixing device150by the operator necessitates the opening and closing of the front door140of the image forming apparatus400. When the front door140of the image forming apparatus400is opened by the operator, the first fixing device150may be exchanged. In addition, when the main switch101is off, the first fixing device150may have been exchanged. Therefore, upon the actuation of the main switch101of the image forming apparatus100and/or the closure of the front door140, the CPU301reads the information out of the memory154of the first fixing device150to acquire the data in the memory154. The control is then effected on the basis of the later one of the pieces of the feeding number information stored in the memory154and the main assembly memory312. By this, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of the more accurate information of the feeding number, and therefore, the deterioration of the image quality of the image on the output recording material102can be suppressed.

In the description of the foregoing embodiment, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170.

In Embodiment 24, when the count of the feeding number for any one of the main-scan direction lengths exceeds the predetermined value during the printing operation, the CPU301carries out the fixing element refreshing operation after the completion of the printing job, and then apparatus shifts to the stand-by mode.

In Embodiment 25, when the total count of the feeding numbers for the main-scan direction lengths exceeds the predetermined value, the CPU301executes the fixing element refreshing operation in the period of the printing job.

The same applies to the second fixing device170.

In the description of this embodiment, the same reference numerals as in Embodiment 24 are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

In the following, the description will be made with respect to the first fixing device150. The same applies to the second fixing device170.

In the main assembly memory312, the number of the recording materials102fed into the first fixing device150is stored for each 5 mm of the main scan direction length of the recording material102in correlation with the ID of the first fixing device150. After the total of the feeding numbers for the respective main scan direction lengths exceeds the predetermined value (500 in this example), the fixing element refreshing operation is executed for the first fixing device150, by the CPU301. Thereafter, the feeding numbers for all of the main scan direction lengths correlated with the ID of the first fixing device150are reset (zero). When the total count exceeds the predetermined value (500 in this example), again, the CPU301executes the fixing element refreshing operation.

In place of counting the recording materials for each main scan direction length on the main assembly memory312, all the recording materials fed into the first fixing device150may be counted irrespective of the main scan direction length.

The fixing element refreshing operation in this embodiment (in the period of the execution of the printing job) may be carried out after the interruption of the printing job (that is, by expanding the interval between the adjacent recording materials102fed into the first fixing device150), or while printing is continuously carried out (that is, while executing the fixing process operation). However, the former is preferable. In such a case, the likelihood of the production of the disturbance of the toner image during the fixing process operation attributable to the vibration or the like caused by the contact of the refreshing roller156to the fixing roller151for the execution of the fixing element refreshing operation can be reduced.

Referring to flow charts ofFIGS. 24 and 25of Embodiment 24 and the flow charts ofFIGS. 29 and 30, the description will be made. The operations in flow chart are carried out by the CPU301as the executing portion controlling the operation of the various mechanisms of the image forming apparatus400on the basis of control programs stored in the ROM303. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

(37.1. Sequence Upon Actuation of the Main Switch and Upon Closing the Front Door)

The sequence upon actuation of the main switch and upon closing the front door will be described referring to the flowchart ofFIGS. 24 and 25.

In this embodiment, in steps S2102(FIG. 24) and S2203(FIG. 25), the operation proceeds to the refreshing sequence ofFIG. 29.

As to the other structures, they are the same as those of Embodiment 24, and the descriptions thereof are omitted for the sake of simplicity.

FIG. 29is a flow chart of a refreshing sequence. The flow chart ofFIG. 29shows the details of step S2102(FIG. 25), and step S2203(FIG. 25) and the refreshing sequence in step S2615which will be described hereinafter.

Steps S2501-S2504are the same as steps S2301-S2304ofFIG. 26, and therefore, the description thereof is omitted for the sake of simplicity.

If the result of discrimination in S2504is negative, the CPU301makes a discrimination in step S2506on the basis of the number information stored in the main assembly memory312corresponding to the ID of the fixing device acquired in step S2501. If the total count of the feeding numbers for all of the main scan direction lengths correlated with the ID of the first fixing device150is not more than the predetermined number (500in this example) in step S2506, the CPU301proceeds to step S2509. In this case, the main assembly memory312already stores the feeding number to be set for the counter. If the result of discrimination in step S2506is negative, the operation may proceed to step S2511.

If, on the other hand, the total count of the feeding numbers for all of the main scan direction lengths correlated with the ID of the first fixing device150exceeds the predetermined number (500in this example) in step S2506, the CPU301proceeds to step S2507.

The step S2507is the same as step S2307ofFIG. 26, and therefore, the description thereof is omitted.

After the completion of the fixing element refreshing operation, the CPU301sets the counts for the respective main scan direction lengths to zero. That is, the counts in the main assembly memory312are reset (S2508). By this, when the total count exceeds again the predetermined number after the execution of the fixing element refreshing operation, the CPU301can execute the fixing element refreshing operation. The CPU301makes the recording in correlation with the ID of the first fixing device150. By this, the information indicative of the execution of the fixing element refreshing operation is recorded in the main assembly memory312in correlation with the ID of the first fixing device150.

Steps S2509and S2510are the same as steps S2309and S2310ofFIG. 26, and therefore, the description thereof is omitted.

On the other hand, if the result of discrimination in step S2503is negative, and if the result of discrimination in step S2504is affirmative, the CPU301makes and the discrimination in step S2505on the basis of the number information of the memory154of the first fixing device150. In step S2505, the total count of the feeding numbers for all of the main scan direction lengths stored in the memory154exceeds the predetermined number (500in this example), the CPU301proceeds to step S2507to execute the fixing element refreshing operation. If, on the other hand, the total count of the feeding numbers for all of the main scan direction lengths stored in the memory154is not more than the predetermined number (500in this example), the CPU301proceeds to step S2511.

A step S2511is the same as step S2311ofFIG. 26, and therefore, the description thereof is omitted.

(37.3. Sequence for Recording Material Counting)

FIG. 30is a flow chart of counting of the recording materials. More particularly, it is a flow chart of printing job execution by the image forming apparatus400.

Steps S2601and S2602are the same as steps S2401and S2402(FIG. 27), and therefore, the description is omitted.

If the CPU301detects that the recording material102is fed to the first fixing device150(S2604, Yes) before the printing job is finished (S2603, No), the CPU301increments the count of the main assembly memory312. The CPU301increments the count for the ID of the first fixing device150. The ID of the first fixing device150has already been acquired in step S2501of the refreshing sequence ofFIG. 29which is executed in response to the actuation of the main switch101or the closure of the front door140. The CPU301increments the count for the main scan direction length of the recording material102fed to the fixing device, of the counts stored in the main assembly memory312. The information of the main scan direction length of the fed recording material102is acquired by the CPU301on the basis of the content of the printing job in step S2601. The CPU301detects the feeding of the recording material102to the first fixing device150depending on the signal from the sensor155.

On the other hand, if the feeding of the recording material102to the first fixing device150is not detected in step S2604, the CPU301does not increment the count, and proceeds to step S2606. This occurs, for example, in the case that after the detection of the passage of the recording material102, the passage of the next recording material102is not detected after elapse of predetermined time, despite the non-completion of the printing job. The predetermined time period is counted by the timer307.

If the CPU301detects the jamming in the image forming apparatus400(S2606), the CPU301proceeds to step S2612.

The steps S2612-S2614are the same as steps S2407-S2409ofFIG. 27, respectively.

In step S2615, the CPU301executes the refreshing sequence ofFIG. 29.

The steps S2616-S2617are the same as steps S2411-S2412ofFIG. 27, respectively.

If the jamming in the image forming apparatus400is not detected in step S2606, the CPU301proceeds to step S2607.

In step S2607, the CPU301discriminates whether or not the total count of the feeding numbers for all of the main scan direction lengths correlated with the ID of the first fixing device150in the main assembly memory312exceeds the predetermined number (500in this example).

If the total count of the feeding numbers for all of the main scan direction lengths correlated with the ID of the first fixing device150is not more than the predetermined number (500in this example) in step S2607, the CPU301proceeds to step S2603. The CPU301continuous the execution of the printing job until it is finished.

If, on the other hand, the total count of the feeding numbers for all of the main scan direction lengths correlated with the ID of the first fixing device150exceeds the predetermined number (500in this example) in step S2607, the CPU301proceeds to step S2608.

In step S2608, the CPU301executes the fixing element refreshing operation.

Steps S2602-S2611are the same as steps S2415-S2417ofFIG. 27, and therefore, the description thereof is omitted for the sake of simplicity.

Thereafter, the operation returns to step S2603, where the CPU301continues the printing job until the printing job is finished.

After the printing job is completed (S603, Yes), the CPU301shifts to the stand-by mode.

As described hereinbefore, the exchange of the first fixing device150by the operator necessitates the opening and closing of the front door140of the image forming apparatus100. When the front door140of the image forming apparatus400is opened by the operator, the first fixing device150may be exchanged. In addition, when the main switch101is off, the first fixing device150may have been exchanged. Therefore, upon the actuation of the main switch101of the image forming apparatus100and/or the closure of the front door140, the CPU301reads the information out of the memory154of the first fixing device150to acquire the data in the memory154. The control is then effected on the basis of the later one of the pieces of the feeding number information stored in the memory154and the main assembly memory312. By this, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of the more accurate information of the feeding number, and therefore, the deterioration of the image quality of the image on the output recording material102can be suppressed.

In the description of the foregoing embodiment, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170.

In Embodiment 24 and Embodiment 25, the CPU (recording portion, writing portion)301stores the time and day information in the memory154and the main assembly memory312as the information for discriminating which information in the memory154and the main assembly memory312should be based. The same applies to the second fixing device170.

In this embodiment, the information indicative of the number of the recordings into the memory154is stored in place of the time and day information.

The description will be made particularly on the difference from Embodiment 24. In the description of this embodiment, the same reference numerals as in Embodiment 24 are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.

The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

In this embodiment the memory154of the first fixing device150as the fixing storing portion stores the number information and a cumulative number of recordings of the number information (number information) in the memory154. The memory154stores the ID of the fixing device (fixing device A, for example) as the identifying information for discriminating the fixing device from the other fixing devices, and therefore, the memory154functions as the discrimination portion.

On the other hand, the main assembly memory312as the main assembly storing portion stores the same number information recorded in the memory154, the number information in correlation with the fixing device ID of the first fixing device150.

The CPU301renews and records the number of the number information stored in the memory154each time the number information is recorded in the memory154.

The CPU301compares the number information stored in the memory154of the first fixing device150mounted in the image forming apparatus400and the number information stored in the main assembly memory312, and discriminates which is larger. The CPU301counts the feeding number on the basis of the number information with the larger one of the number information.

In this embodiment, the memory154stores the cumulated count of the recordings of the number information as the number information, but the cumulative number may be counted including the number of recordings other than the number information. In such a case, when (1) the information other than the number information is written, (2) the number information is written, and then (3) the number information is written, the cumulative number is three.

Referring to flow charts ofFIGS. 24 and 25of Embodiment 24 and the flow charts ofFIGS. 31 and 32, the description will be made. The operations in flow chart are carried out by the CPU301as the executing portion controlling the operation of the various mechanisms of the image forming apparatus400on the basis of control programs stored in the ROM303. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

(38.1. Sequence Upon Actuation of the Main Switch and Upon Closing the Front Door)

The sequence upon actuation of the main switch and upon closing the front door will be described referring to the flowchart ofFIGS. 24 and 25.

In this embodiment, in steps S2102(FIG. 24) and S2203(FIG. 25), the operation proceeds to the refreshing sequence ofFIG. 31.

As to the other structures, they are the same as those of Embodiment 24, and the description thereof are omitted for the sake of simplicity.

FIG. 31is a flow chart of a refreshing sequence. The flow chart ofFIG. 31shows the details of step S2102(FIG. 24), and step S2203(FIG. 25) and the refreshing sequence in step S2810, which will be described hereinafter.

The steps S2701-S2703are the same as steps S2301-S2303ofFIG. 26, respectively.

If the result of discrimination in the step S2703is Yes, the CPU301discriminates which one of the number information of the memory154and the number in the main assembly memory312is to be used (S2704). More specifically, it is discriminated as to whether or not the number-of-times information stored in the memory154is larger than the number-of-times information stored in the main assembly memory312in correlation with the ID of the first fixing device150.

If the result of the discrimination is affirmative (S2704, YeS2), the CPU301proceed to step S2705.

If, on the other hand, the results of the discrimination is negative (S2704, No), the CPU301proceeds to step S2706. If, the number-of-times information stored in the memory154is the same as the number-of-times information stored in the main assembly memory312in correlation with the ID of the first fixing device150(S2704, No), the CPU301proceeds to step S2706.

The step S2705is the same as step S2305ofFIG. 26.

The step S2706is the same as step S2306ofFIG. 26.

The step S2707is the same as step S2307ofFIG. 26.

The step S2708is the same as step S2308ofFIG. 26.

The step S2709is the same as step S2309ofFIG. 26.

In step S2710, the CPU301stores the number-of-times information in the memory154and the main assembly memory312. In the main assembly memory312, the record is made in correlation with the ID of the first fixing device150. When the larger one of the number-of-times as a result of comparison in step S2704(larger one of the number-of-times information stored in the memory154and the number-of-times information stored in the main assembly memory312in correlation with the ID of the first fixing device150) is N, the N+1 is recorded as the number-of-times information at step S2710. Here, N is an integer not less than 0. In step S2710, N+1 is stored as the number-of-times information.

Step S2711is the same as step S2311ofFIG. 26.

(38.3. Sequence for Recording Material Counting)

FIG. 32is a flow chart of counting of the recording materials. More particularly, it is a flow chart of printing job execution by the image forming apparatus400.

The steps S2801-S2807are the same as steps S2401-S2407ofFIG. 27, respectively.

In step S2808, the CPU301stores the number-of-times information in the memory154and the main assembly memory312. Here, when the number-of-times information stored in the memory154and the main assembly memory312indicate M, the number-of-times information M+1 is recorded. In the main assembly memory312, the record is made in correlation with the ID of the first fixing device150.

Upon the actuation of the main switch, the opening of the front door140, the above-described refreshing sequence (FIG. 31) after the jam clearance, the same number-of-times information is recorded in the memory154and the main assembly memory312.

The step S2809is the same as step S2409ofFIG. 27.

In step S2810, the CPU301executes the refreshing sequence ofFIG. 31.

The steps S2812-S2812are the same as steps S2411-S2412ofFIG. 27, respectively.

The steps S2813-S2816are the same as steps S2413-S2416ofFIG. 27, respectively.

In step S2817, the CPU301stores the number-of-times information in the memory154and the main assembly memory312. Here, when the number-of-times information stored in the memory154and the main assembly memory312indicate L, the number-of-times information L+1 is recorded. In the main assembly memory312, the record is made in correlation with the ID of the first fixing device150.

The step S2818is the same as the step S2418ofFIG. 27.

As described hereinbefore, the exchange of the first fixing device150by the operator necessitates the opening and closing of the front door140of the image forming apparatus400. When the front door140of the image forming apparatus400is opened by the operator, the first fixing device150may be exchanged. In addition, when the main switch101is off, the first fixing device150may have been exchanged. Therefore, upon the actuation of the main switch101of the image forming apparatus400and/or the closure of the front door140, the CPU301reads the information out of the memory154of the first fixing device150to acquire the data in the memory154. The control is then effected on the basis of the later one of the pieces of the feeding number information stored in the memory154and the main assembly memory312. By this, the CPU301can execute the fixing element refreshing operation for the first fixing device150on the basis of the more accurate information of the feeding number, and therefore, the deterioration of the image quality of the image on the output recording material102can be suppressed.

In the description of the foregoing embodiment, the description has been made with respect to the first fixing device150, but the same applies to the second fixing device170.

In the foregoing, an integer not less than 0 is recorded as the number-of-times information, and the number-of-times information is incremented by 1 for each recording of the information in the memory154by the CPU301, but the number-of-times information recording method is not limited to such an example. Referring toFIG. 31, another method will be described.

The number of times which is larger as a result of comparison in step S2704between the number-of-times information stored in the memory154and the number-of-times information stored in the main assembly memory312in correlation with the ID of the first fixing device150is X. Suppose that in step S2710, the CPU301records X+Y as the number-of-times information.

At this time, Y may be 0.1, so that the CPU301increments the number-of-times information by 0.1 for each recording of the information in the memory154. In such a case, the number of times (X, Y, X+Y) of the number-of-times information includes a non-integer.

At this time, Y may be 2, so that the CPU301increments the number-of-times information by 2 for each recording of the information in the memory154.

Alternatively, Y may be −1, so that the CPU301decrements the number-of-times information by 1 for each recording of the information in the memory154. In this case, the number of times (X, Y, X+Y) of the number-of-times information includes a negative number. Further in this case, in step S2704, the CPU301proceeds to step S2705, if the value indicated by the number-of-times information of the memory154is smaller than the value indicated by the number-of-times information of the main assembly memory312correlated with the ID of the first fixing device150(S2704, YeS2). For example, this is the case when the number-of-times information of the memory154indicates −4, and the number-of-times information of the main assembly memory312indicates −2. If, on the other hand, the value indicated by the number-of-times information of the memory154is not smaller than the value indicated by the number-of-times information of the main assembly memory312correlated with the ID of the first fixing device150(S2704, No), the CPU301proceeds to step S2706.

In the foregoing, the description that has been made particularly about the difference from Embodiment 24, but this embodiment may be incorporated in the Embodiment 25 in place of the time and day information stored in the memory154. The detailed description of such a modification is omitted for the sake of simplicity.

In foregoing Embodiments 24-26, the IDs of the fixing device as the identifying information are stored in the memories154,174, respectively, and therefore, the memories154,174function also as the discrimination portion, but the method for discriminating the fixing device is not limited to such a method.

For example, resistors as the discrimination portions may be provided on the first fixing device150, the second fixing device170and the replacement fixing device prepared outside the image forming apparatus400.

The resistors provided on them have resistance values different from each other.

In the state that the first fixing device150is mounted in the image forming apparatus400, a current flowing through the resistor upon the application of a predetermined voltage across the resistor of the first fixing device150is detected.

More specifically, the image forming apparatus400includes, as the means for discriminating the first fixing device150, a voltage application portion for applying the predetermined voltage across the resistor and an ammeter for measuring the current flowing through the resistor. The CPU301monitors the output of the ammeter.

When the regular voltage is applied, the current corresponds to the resistance value one by one because of the Ohm's law. The CPU301acquires an output of the ammeter predetermined resistance of the resistor. The first fixing device150and the replacement fixing device have the resistors having different resistance values, and therefore, the CPU301is capable of discriminating the fixing device depending on the difference of the output of the ammeter. Thus, the resistance value is the identifying information.

The CPU301stores resistance value acquired from the resistor of the first fixing device150mounted in the main assembly in correlation with the number information and the time and day information in main assembly memory312.

In this case, in step S2301(Embodiment 24) ofFIG. 26, step S2501(Embodiment 25) ofFIG. 29, or step S2701ofFIG. 31, the CPU301acquires the resistance value of the resistor of the first fixing device150through the above-described method concurrently with the reading of the information from the memory154of the first fixing device150.

The method of writing (recording) the ID of the fixing device into the main assembly memory312is not limited to the use of the resistance value as the identifying information. For example, the main assembly memory312may include a Table of the correspondence between the resistance values of the resistors, and the number information may be recorded in correlation with the name of the fixing device (fixing device A, for example).

The CPU301may use the output of the ammeter as the identifying information without acquiring the resistance value of the resistor. That is, the CPU301may record the output of the ammeter in the main assembly memory312as in the ID of the fixing device.

The same applies to the means for discriminating the second fixing device170.

In this case, the discrimination member311includes the voltage application portion and the ammeter for discriminating the first fixing device150, and the voltage application portion and the ammeter for discriminating the second fixing device170. The CPU301is connected with the discrimination member311to discriminate the first fixing device150and/or the second fixing device170mounted in the image forming apparatus400. When the first fixing device150is mounted in the image forming apparatus400, the discrimination member311becomes electrically connectable with the resistor of the first fixing device150. In addition, when the second fixing device170is mounted in the image forming apparatus400, the discrimination member311becomes electrically connectable with the resistor of the second fixing device170.

As for another example of the method for discriminating the fixing device, a DIP switch is usable as the discrimination portion provided on the fixing device (first fixing device150, second fixing device170and replacement fixing device).

More particularly, the switches different depending on the individual fixing devices are in ON state beforehand (the on-off state and position of the switches are different depending on the fixing devices). The CPU301is connected with the DIP switch of the fixing device mounted in the image forming apparatus400, and the switch in ON state produces a signal to the CPU301in response to an input signal from the CPU301. The CPU301detects the signal from the ON state switch (acquires the fixing device ID) to discriminate the fixing device.

For example, the CPU301supplies signals to the first and second switches. When the CPU301detects the output signal from the first switch, the CPU301discriminates it is the fixing device A, when the CPU301detects the output signal from the second switch, it is the fixing device B, and when the CPU301detects the signals from both of the first and second switches, it is the fixing device C.

In this case, the discrimination member311shown inFIG. 23includes the DIP switch for discriminating the first fixing device150and the DIP switch for discriminating the second fixing device170. The CPU301is connected with the DIP switches (discrimination member311) of the first fixing device150and/or second fixing device170mounted in the main assembly of the image forming apparatus400, and discriminates them.

The image forming apparatus400may be set at a mode not executing the above-described fixing element refreshing operation, by the setting of the user. In such a case, the operating portion180is provided with a selector which displays for the selection between the mode in which the fixing element refreshing operation is executed and the mode in which it is not executed. The user is capable of selecting one of the modes through the operating portion180. The information of the selected mode is stored in the main assembly memory312as the set information of the image forming apparatus400. The operation program to be executed when the fixing element refreshing operation non-executing mode is selected is stored in the ROM303. When such a mode is selected, the CPU301executes the program.

The fixing element refreshing operation is necessary in order to suppress the glossiness non-uniformity due to the difference in the surface roughness between the (I) non-passing portion, the (II) passing portion, and the (III) boundary area of the fixing roller151, as described hereinbefore. The difference in the surface roughness of the fixing roller151appears as the glossiness unevenness when the recording material102passes through the nip in contact with the (I) non-passing portion, the (II) passing portion, and the (III) boundary area of the fixing roller151. Therefore, the glossiness unevenness can be suppressed by using the different fixing device having the same structure, for the respective main scan direction length of the recording material102as the first fixing device150. In view of this, some user who is concerned with the glossiness property evenness prepares the fixing devices for respective main scan direction length of the recording material102in order to avoid the deterioration of the print quality.

In such a case, that is, the glossiness unevenness caused by the edge portions of the recording materials102, it is desirable not to execute the fixing element refreshing operation to avoid the fine scores provided by the refreshing roller156influences the glossiness property of the image.

By making the modes (execution and non-execution of the fixing element refreshing operation) selectable by the user, the apparatus can meet wider needs of the users.

With respect to the embodiments 24-29, the contact of the end portions of the recording materials102with the fixing roller151is taken as the cause of the difference in glossiness on the fixed image, but the causes are not limited to that. For example, a separation claw contacting the fixing roller151may be provided to prevent the recording material102from wrapping around the fixing roller151.

In such a case, with the cumulation of the fixing process, there is a likelihood that contact damage may occur by the contact of the separation claw to the surface of the fixing roller151. In the case that a plurality of separation claws are provided at intervals in the longitudinal direction (axial direction) of the fixing roller151, the surface of the fixing roller151is roughened adjacent to the contact position with separation claw, with the result of unevenness of the surface state over the length of the fixing roller151. As a result, the glossiness difference may arise on the fixed image.

Even in such a case, the influence to the image quality by the contact damage can be reduced by providing the refreshing roller156and executing the fixing element refreshing operation.

In Embodiments 24-30, the refreshing roller156is provided for the fixing roller151, and the surface of the fixing member is rubbed, but a rubbing rotatable member may be provided for a surface of a pressing belt152and/or a pressing roller172to rub the surface of the pressing member.

A plurality of image forming apparatuses400described in the foregoing may be used to constitute an image forming system.

In the exchangeable fixing device system, the user exchanges the fixing devices depending on the kind of the recording material102or the preference. In such a case, there is a possibility that a better quality prints can be provided if the fixing device not selected by the operator is used, that is, there is a likelihood that the advantage of the exchanging system is not enjoyed. Therefore, the image forming apparatus400notifies the operator of the matching between the selected recording material102and the selected fixing device.

In the following, the description will be made referring to an Embodiment 24 (FIGS. 26 and 27). The other structures are the same as in Embodiment 24, and therefore, the detailed description thereof is omitted for simplicity. The description will be made as to the first fixing device150, but the same applies to the second fixing device170.

The memory154of the first fixing device150stores limiting information indicative of the kinds of the recording material102to be used with the first fixing device150, and functions as a limitation information portion.

In step S2301ofFIG. 26, the CPU301acquires the limiting information concurrently with acquiring the information of the memory154of the first fixing device150mounted in the image forming apparatus400. The CPU301acquires the kinds of the recording material102to be limited for the first fixing device150on the basis of the limiting information.

In step S2401ofFIG. 27, when the CPU301receives the printing job from the operator, the CPU301makes non-selectable the kinds of the recording material102not suitable for the first fixing device150on the selection screen.

Thus, the printing operation using improper first fixing device150can be prevented, thus assuring high quality prints.

The foregoing description has been made with respect to the first fixing device150, but it is applicable to the second fixing device170, and therefore, the description as to the second fixing device170will be omitted.

In this embodiment, the memories154,174are used as the limiting information portion, but the following structure is usable.

For example, a resistor may be used. The first fixing device150is provided with a resistor functioning as a limiting information portion. The fixing device prepared outside the image forming apparatus400as a replacement fixing device is also provided with a resistor as the limiting information portion. The resistance value is different depending on the kind of the recording material102for which the fixing process of the first fixing device150is limited, and functions as the information for limiting the kind of the recording material102for use in the fixing process of the first fixing device150. The method for acquiring the limiting information is the same as the method for acquiring the ID of the above-described fixing device (foregoing embodiments), and the description thereof is omitted.

In the main assembly memory312, the information indicative of the kind of the recording material102to be limited in the fixing process corresponding to the resistance value (limiting information) of the memory (limiting information portion) is stored beforehand. For example, when the resistance value is R4, the fixing on envelope is prevented, and when the resistance value is R5, the fixing on thick sheet is prevented.

The information corresponding to the kinds of the recording material102to be prevented may not be stored in the main assembly memory312in combination with the limiting information. For example, the program executed by the CPU301may prevent the fixing process on the recording material102depending on the resistance value of the resistor (limiting information portion). In such a case, the program is stored in the ROM303.

For example, the limiting information portion provided on the fixing device (first fixing device150, second fixing device170, and replacement fixing device) may be DIP switch including a plurality of switches. In such a case, the switches different depending on the fixing devices are in ON state beforehand as the limiting information, and the CPU301determines the kind of the recording material102to be prevented on the basis of the signal from the ON state switches. The other structures are the same as those of the DIP switch as the discrimination portion described hereinbefore.

In this embodiment, the limiting information portion and the discrimination portion are separate members on the fixing device, but one resistor or memory may include the limiting information portion and the discrimination portion.

In addition, this embodiment may be incorporated in Embodiment 25 or 26, although the description is made with respect to the case in which this embodiment is incorporated in Embodiment 24. The description as to the case in which this embodiment is incorporated in Embodiments 25 and 26 is omitted, because the foregoing description applies to such a case.

In the foregoing description of Embodiments 24-33, the operating portion180is provided with a display screen and a selection key, but the display screen may be a touch panel which also functions as a selector.

In the foregoing Embodiments 24-34, the image forming apparatus400comprises both of the first fixing device150and the second fixing device170(tandem fixing). However, the present invention is applicable to an image forming apparatus400comprising only one fixing device150.

In the Embodiments 24-35, the image forming apparatus400comprises the image forming stations (120-123) for forming yellow, magenta, cyan, and black toner images (color image forming apparatus), but the present invention is applicable to a monochromatic image forming apparatus. For example, there is a monochromatic image forming station for forming the toner images in black only.

In the Embodiments 24-36, the image forming apparatus400comprises an intermediary transfer belt115as an intermediary transfer member (intermediary transfer type), but the present invention is applicable to a direct transfer type apparatus as follows.

In such a case, the image forming station309includes the image forming stations (120-123) and a transfer feeding belt functioning as a transfer portion. The image forming stations (120-123) can be contacted by the transfer feeding belt. The image forming apparatus400feeds the recording material102from a recording material accommodating portion103to the transfer feeding belt. The transfer feeding belt electrostatically attracts the recording material102and carries it to a position where the recording material102faces the image forming station, and a transfer roller is provided in the inside of the belt. The transfer roller transfers the toner image formed on the image bearing member onto the recording material102carried on the transfer feeding belt. By this, the toner image (unfixed) is formed on the recording material102.

This application claims the benefit of Japanese Patent Applications Nos. 2015-151202 filed on Jul. 30, 2015, 2015-151203 filed on Jul. 30, 2015, and 2015-151204 filed on Jul. 30, 2015, which are hereby incorporated by reference herein in their entirety.