Image forming apparatus with cleaning sheet remaining amount detection

A locking arm for locking a cleaning unit using a cleaning sheet, a sensor for detecting a remaining amount of the cleaning sheet, a CPU for prohibiting an image forming operation depending on an output of the sensor, and an interrelating arm acting on the sensor so as to prohibit the image forming operation when locking by the locking arm is in an unlocked state.

TECHNICAL FIELD

The present invention relates to an image forming apparatus for forming a toner image on a recording material.

BACKGROUND ART

Conventionally, the image forming apparatus, such as a copying machine, a printer or FAX (facsimile machine), in which an image is formed using an electrophotographic process, has been known. The image forming apparatus of this type includes a fixing device for fixing the toner image on the recording material by heating and pressing the toner image.

In the fixing device, a cleaning device for cleaning offset toner transferred onto a fixing roller (heating portion) is provided (see Japanese Laid-Open Patent Application Hei 6-194986 and Japanese Laid-Open Patent Application 2004-212409).

Further, as such a cleaning device, a type using a cleaning sheet of a winding-up type (hereinafter, referred to as a web) has been known. Further, the cleaning device using the web is provided with a means for detecting a remaining amount of the web. Then, when the remaining amount of the web is in a small (little) state, notification to the effect that exchange of the web is prompted is made.

Therefore, in the case where the cleaning device is constituted as a cleaning unit detachably mountable to the image forming apparatus so that the web can be exchanged, in order to maintain a predetermined positional relationship with an object to be cleaned, the cleaning unit may preferably be locked. Further, on the other hand, for maintenance such as exchange of the cleaning unit, the cleaning unit is also in an unlocked state.

Thus, in the case where a mechanism for locking/unlocking the cleaning unit is provided, there is a liability that after the exchange of the cleaning unit, the cleaning unit is kept in the unlocked state due to an operational error. In such a state, there is a liability that the cleaning device cannot achieve sufficient cleaning performance. Recently, it is required to not only avoid such a situation but also achieve the sufficient cleaning performance without inviting an increase in cost.

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

An object of the present invention is to provide an image forming apparatus in which a cleaning device is capable of achieving sufficient cleaning performance.

Means for Solving the Problem

According to an aspect of the present invention, there is provided an image forming apparatus comprising: an image forming portion for forming a toner image on a recording material; a heating portion for heating the toner image formed on the recording material by the image forming portion; a cartridge including a cleaning sheet for cleaning the heating portion, a roller about which the cleaning sheet is wound, and a roller for winding up the cleaning sheet; a locking portion for locking said cartridge; a detecting portion for detecting a remaining amount of the cleaning sheet; a prohibiting portion for prohibiting an image forming operation depending on an output of the detecting portion; and an acting portion for acting on the detecting portion so as to prohibit the image forming operation when the locking portion is in an unlocked state.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

In the following, embodiments for carrying out the present invention will be described with reference to embodiments relating to an image forming apparatus shown in the attached drawings. In the following embodiments, a structure of the image forming apparatus of an electrophotographic type using, as a heating portion (image heating apparatus), a fixing device for fixing a toner image will be described as an example. Incidentally, the embodiments shown below are only examples, and for example, as regards a detailed structure, a person skilled in the art can appropriately change it with a range not departing from the scope (object) of the present invention. Further, numerical values taken up in the embodiments are reference numerical values and do not limit the present invention.

In the following, the embodiments of the present invention will be specifically described with reference to the drawings.

FIG. 1shows a structure of image forming portions and a control system of an image forming apparatus capable of carrying out the present invention. An image forming apparatus100inFIG. 1is constituted as an intermediary transfer type full-color printer of a tandem type. An image forming mechanism thereof includes image forming portions Pa, Pb, Pc and Pd of an electrophotographic type, which are arranged along an intermediary transfer belt130, for forming images of respective colors of yellow, magenta, cyan and black. Here, first, a flow of an entirety of image formation will be schematically described.

The image forming portions Pa, Pb, Pc and Pd include exposure devices La, Lb, Lc and Ld, photosensitive drums3a,3b,3cand3d, and developing devices1a,1b,1cand1d, respectively. At the respective image forming portions Pa, Pb, Pc and Pd, by the exposure devices La, Lb, Lc and Ld, photosensitive surfaces of the photosensitive drums3a,3b,3cand3dare irradiated with laser light beams modulated by image signals, so that electrostatic latent images corresponding to respective color components are formed. Thereafter, the electrostatic latent images on the photosensitive drums3a,3b,3cand3dare developed by the developing devices1a,1b,1cand1d, respectively, so that toner images of the respective colors of yellow, magenta, cyan and black are formed on the respective photosensitive drums3a,3b,3cand3d. The respective color toner images on the photosensitive drums3a,3b,3cand3dare timed to each other and are transferred onto the intermediary transfer belt130. The four color toner images transferred on the intermediary transfer belt130are fed to a position of secondary transfer rollers11and14, and then are secondary-transferred onto a sheet P.

The sheet P as the recording material onto which this toner image is transferred is formed of a material such as paper or plastics, for example, and is accommodated in a sheet cassette10at a lower portion of image forming apparatus100. The sheet P is fed one by one from the sheet cassette10by an unshown pick-up roller or the like, and is fed in an S-shaped feeding path P1as shown inFIG. 1and reaches a position of registration rollers12.

The registration rollers12send the sheet P to a secondary transfer portion T2while being timed to the toner images on the intermediary transfer belt130. The sheet P on which the four color toner images are secondary-transferred at the secondary transfer portion T2from the intermediary transfer belt130is subjected to a heat-fixing (heating and pressing) process of a fixing device9, so that the toner images are fixed thereon, and thereafter the sheet P is discharged onto a discharge tray68outside image forming apparatus100(machine).

In the case of double-side printing, the sheet P on which the toner images are fixed on a first surface by the fixing device9is induced into a reversing path P2and is switched back to be turned upside down so as to replace a leading end and a trailing end with each other, and then is fed again to the feeding path P1and is fed again to the registration rollers12. Then, at the secondary transfer portion T2, the toner images are transferred onto the second surface of the sheet P, and then are fixed by the fixing device9, and thereafter the sheet P is discharged onto the discharge tray68.

Incidentally, in the image forming apparatus100in this embodiment, the above-described photosensitive drums3a,3b,3cand3d, the respective feeding rollers, belts and the like are driven by unshown driving mechanism and driving source, and driving timing of these members is synchronously controlled by a control device (control system) principally including a CPU500described later.

Here, a constitution of the image forming portions Pa, Pb, Pc and Pd and a periphery of the intermediary transfer belt130will be described in detail. The image forming portions Pa, Pb, Pc and Pd have the substantially same constitution except that the colors of toners of yellow, magenta, cyan and black used in developing devices1a,1b,1cand1dare different from each other. Accordingly, in the following description, the image forming portion Pa will be described and other image forming portions Pb, Pc and Pd will be omitted from redundant description. Structures of the other image forming portions Pb, Pc and Pd which are not specifically described below correspond to constitutions in which suffixes of respective members having the reference symbol a are read as b, c and d.

The image forming portion Pa is constituted so that a charging device2a, the exposure device La, the developing device1a, a transfer roller24a, and a drum cleaning device4aare provided so as to surround the photosensitive drum3a. The photosensitive drum3ais prepared by forming a photosensitive layer on an outer peripheral surface of an aluminum cylinder, for example, and is rotationally driven in an arrow direction at a predetermined process speed.

The charging device2aelectrically charges the surface of the photosensitive drum3ato a uniform potential (polarity is a negative polarity, for example). The exposure device La forms an electrostatic image on the photosensitive drum3aby scanning through a rotating mirror with a laser beam obtained by subjecting a scanning line image signal, corresponding to an image of a recording color (yellow in this case), to ON-OFF modulation. Incidentally, inFIG. 1, the exposure devices La, Lb, Lc and Ld corresponding to respective recording colors are illustrated as separate blocks, but a part of an optical system is common to the respective recording colors in some cases, and an actual structure is arbitrary. Structures of these exposure devices do not constitute the present invention.

The developing device1adevelops the electrostatic image into the toner image by transferring the toner onto the photosensitive drum3a. A toner cartridge Ea provided together with the developing device1asupplies the toner, in an amount correspondingly to an amount consumed by the image formation, to the developing device1a. The transfer roller24aurges the intermediary transfer belt130to form a transfer portion between the photosensitive drum3aand the intermediary transfer belt130. Further, by applying a positive DC voltage to the transfer roller24a, for example, the negative toner image carried on the photosensitive drum3ais transferred onto the intermediary transfer belt130.

The intermediary transfer belt130is stretched and supported by a tension roller15, the secondary transfer roller14and a driving roller13, and is driven and rotated in an arrow A direction by the driving roller13. The secondary transfer roller11is provided opposed to the secondary transfer roller14inside the intermediary transfer belt130and contacts the intermediary transfer belt130, whereby the secondary transfer portion T2is formed. By applying, e.g., a positive DC voltage to this secondary transfer roller11, the toner image is transferred from the intermediary transfer belt130onto the sheet P passing through a position of the secondary transfer portion T2.

The drum cleaning device4aof the image forming portion Pa rubs the photosensitive drum3awith, e.g., a cleaning blade to collect a transfer residual toner on the photosensitive drum3a. Further, as regards the intermediary transfer belt130, a belt cleaning device22is provided at a position of the tension roller15.

The belt cleaning device22may be constituted from a cleaning mechanism using a cleaning blade, for example, or may also be constituted by a web cleaning type similarly as a cleaning unit used for the fixing device9described later. In the case of the web cleaning type, a belt cleaning device22rubs the intermediary transfer belt130with a cleaning web to collect a transfer residual toner on the intermediary transfer belt130.

The developing device1ais capable of using the toner containing (incorporating), e.g., paraffin, a wax consisting of polyolefin or a silicone oil as a parting agent. A so-called polymerization toner of this type can be manufactured by finely dispersing a wax component and a pigment into a pulverized toner, for example. An object of use of the toner containing the parting agent as described above is to prevent offset of the toner onto a fixing roller40of the fixing device9described later, for example. The toner as described above is accommodated in the toner cartridge Ea, for example, and is supplied from the toner cartridge Ea to the developing device1a.

The respective color toner images formed by the above-constituted image forming portion Pa and the image forming portions Pb, Pc and Pd having a similar constitution are transferred to the intermediary transfer belt130and are fed to the position of the secondary transfer portion T2. Then, at the position of the secondary transfer portion T2, the toner images on the intermediary transfer belt130are transferred onto the sheet P.

The sheet P on which the toner images are transferred is fed to the fixing device9on the feeding path P1. The fixing device9fixes the toner images transferred on the sheet P by heating and pressing the toner images. The constitution of a periphery of the fixing device9will be specifically described later.

The image forming apparatus100inFIG. 1includes a control system as shown at an upper left portion of the figure. This control system includes, as a main control portion (controller), the CPU500consisting of a general-purpose microprocessor or the like, for example.

The CPU500constitutes the main controller for controlling an entirety of an image forming operation of the image forming apparatus100in this embodiment. Particularly, in this embodiment, the CPU500constitutes a permitting means (permitting portion) for permitting the image forming operation or a prohibiting means (prohibiting portion) for prohibiting the image forming operation depending on detection of a remaining amount of a cleaning sheet61of a cleaning unit60described later.

As described later, the cleaning unit60accommodates a non-endless cleaning sheet61for cleaning a rotatable heating member (fixing roller40) for heating the toner images formed by the image forming portions Pa, Pb, Pc and Pd. This cleaning unit60includes a winding-up mechanism (web supplying roller61a-web cleaning unit roller61b) for winding up the cleaning sheet61and is constituted as a detachably mountable cartridge.

Further, in this embodiment, a photo-sensor (photo-interrupter)72and a remaining amount detecting flag which are used as a detecting means (detecting portion) for detecting the remaining amount of the cleaning sheet61are provided. Particularly, the above-described prohibiting means constituted using the CPU500prohibits the image forming operation depending on an output of the detecting means. Or, depending on a mode of the remaining amount detection, the above-described permitting means constituted using the CPU500permits the number of times of the image forming operation corresponding to the remaining amount of the cleaning sheet61.

Further, in this embodiment, the cleaning unit (cartridge)60having the detachably mountable cartridge constitution is locked to a principal portion of a cleaning device600. For that reason, a locking means (locking portion) including a dial-shaped web locking knob73, a locking arm74and the like is provided. Further, in this embodiment, as described later, when the locking means is in a locking-released state, (proper cleaning cannot be performed and therefore) an acting means (acting portion, interrelating portion) acting on the detecting means (photo-sensor72, photo-interrupter77and the like) is provided so that the image forming operation is prohibited. This acting means is principally constituted, in an example described later, by the photo-sensor72and photo-interrupter77as the detecting means and an interrelating arm75for interrelating the locking arm74as the locking means, for example. Thus, a locked state of the cleaning unit60having the detachably mountable cartridge constitution is detected by using the (remaining amount) detecting means for detecting the remaining amount of the cleaning sheet61, and when the locking means is in the locking-released state, control is carried out so as to prohibit the image forming operation.

Incidentally, naturally, when the locking means for locking the cleaning unit60having the cartridge constitution is in the locked state, control is carried out so as to permit the image forming operation. For example, the above-described acting means (e.g., the interrelating arm75) is constituted so as to be in a non-acting state on the remaining amount detecting means for the cleaning sheet61when the locking means for locking the cleaning unit60is in the locked state.

To a system bus of the CPU500, memories such as an ROM501and an RAM502are connected. The ROM501can be used for storing a control program of the CPU500described later, for example. In that case, the ROM501is exchanged or constituted by a device such as E(E)PROM capable of rewriting a part of an area thereof, and then the control program according to the present invention can be renewed by a method in which contents of the device is rewritten or the like. The RAM502is used as a working area of the CPU500or a cash memory of image data relating to image formation.

The CPU500controls an operation of an entirety of the apparatus, but in a block diagram ofFIG. 1at an upper left portion, as a representative of a member to be controlled by the CPU500, particularly only one block (circle mark) of a driven portion506is shown. This driven portion506represents a motor, a solenoid, various sensors and the like which are provided in a feeding system such as the sheet P, the intermediary transfer belt130, the fixing device9and the like, for example. The driven portion506is connected to the system bus of the CPU500via an interface503constituted by a driver circuit suitable for the motor, the solenoid, the various sensors and the like used in the driven portion506and by an interface circuit with the system bus.

Further, to the system bus of the CPU500, an external storing device504can also be connected. The external storing device504can be constituted by a disk device such as HDD or SSD, an optical disk device using media such as CD-ROM and DVD, or various flash memories. Also this external storing device504can be used for storing the control program of the CPU500described later, for example. Particularly, in the case where the external storing device504uses a detachably mountable memory device such as the optical disk or the flash memory, this memory device can be used as a computer readable recording medium for supplying the control program according to the present invention.

Further, to the system bus of the CPU500, as a user interface means, e.g., an operating panel505is connected. The operating panel505is constituted by a display device such as an LED panel, a keyboard (or a touch panel), or further a voice (audio) outputting device such as a voice synthesizing means, an amplifying circuit, a speaker or the like. The operating panel (display portion)505is capable of displaying not only an image formation instruction, a display for designating an image forming condition, a display of an operating state of the apparatus (device) and the like, but also a message, such as warning information, to a user. Particularly, in a control procedure described later, the operating panel505can be used as a notifying means (notifying portion) for outputting warning information for warning a small remaining amount state of the cleaning sheet61. For outputting this warning information (warning message), the display outputting means or the voice synthesizing and outputting means as described above is used.

Further, to the interface503, as a remaining amount sensor for detecting the remaining amount of the cleaning sheet61of the cleaning device600provided together with the fixing device9described later, the photo-sensor72is connected. By this, the CPU500can read a detection state of the photo-sensor72via the interface503.

Further, to the interface503, for the purpose of maintenance or the like, a sensor82for detecting an open and close state of a door (exchange door)81for permitting access to an inside of an apparatus casing of the image forming apparatus100. The door81is opened and closed for performing maintenance of the cleaning device600provided together with the fixing device9, for example. InFIG. 1, the door81is illustrated so as to be provided at a position of a lower-left front surface, but the position and a size thereof are arbitrary, and for example, the door81may be disposed at a side surface of the image forming apparatus100or may be constituted with a size such that the door81is opened and closed in a relatively large range at a lower portion of a front surface. The sensor82can be constituted by an arbitrary sensor device, capable of detecting an open and close state of the door81, such as a photo-sensor or a limit switch for detecting a tab provided on the door81. The CPU500can read a detected state of the sensor82via the interface503.

A peripheral structure of the fixing device9in this embodiment is shown inFIG. 2. The fixing device9in this embodiment includes the fixing roller40as a rotatable heating member for heating the toner images formed on the recording material (sheet P). In this embodiment, with regard to this fixing device9, the cleaning device600for removing the toner offset (transferred) from the sheet P is disposed for the fixing roller40. The cleaning device600is constituted by a web cleaning mechanism. In this embodiment, the cleaning unit60having the cartridge mechanism is mounted to and demounted from the cleaning device600, and a structure for locking and unlocking (lock-releasing) will be described later in detail. InFIG. 2, a functional relationship between the cleaning device600and the fixing roller40will be principally described.

FIG. 2shows a schematic sectional structure of the fixing device9, and the sheet P on which unfixed toner images T are formed as described above is fed into the fixing device9from a right side ofFIG. 2. The fixing roller40and a pressing roller41are connected with each other by an unshown gear mechanism connecting gears fixed to shaft ends thereof in one side, for example, and are rotationally driven integrally by an unshown driving system, thus being rotated in arrow directions, respectively. The pressing roller41is constituted so as to be press-contacted to the fixing roller40at a total pressure of, e.g., about 784 N (about 80 kgf), so that a nip for nipping the sheet P is formed. The sheet P is nipped and fed by a heating nip between the fixing roller40and the pressing roller41, and by this, the toner images T are fixed on the sheet P (fixing by heating and pressing).

The fixing roller40is rotatably supported via bearings by unshown ball bearings or the like at both end portions thereof. The fixing roller40is constituted in a diameter of, e.g., about 60 mm by disposing an about 3 mm-thick elastic layer40con an outer peripheral surface of a core metal40bconsisting of, e.g., a hollow aluminum cylinder or the like. A lower layer of the elastic layer40cis, e.g., a HTV (high-temperature vulcanizing) silicone rubber layer, and on an outer peripheral surface of this HTV silicone rubber layer, an RTV (room-temperature vulcanizing) silicone rubber layer is disposed as a heat-resistant elastic layer directly contacting an image surface of the sheet P. At a rotation center of the fixing roller40, inside the core metal40b, a halogen heater40afor heating the fixing roller40from an inside is disposed. This halogen heater40ainside this core metal40bis supported, e.g., in a non-rotation state, by an unshown supporting means.

The pressing roller41contacting the fixing roller40is rotatably supported via bearings by unshown ball bearings or the like at both end portions thereof. The pressing roller41is constituted in a diameter of 60 mm by disposing an about 1 mm-thick elastic layer41con an outer peripheral surface of an aluminum cylindrical core metal41b. A lower layer of the elastic layer41cis, e.g., a HTV silicone rubber layer, and on an outer peripheral surface of this HTV silicone rubber layer, e.g., a fluorine-containing resin layer is disposed as a parting layer. At a rotation center of the pressing roller41, inside the core metal41b, a halogen heater41afor heating the pressing roller41from an inside is disposed non-rotatably. Also the halogen heater41ainside this core metal41bis supported, e.g., in a non-rotation state, by an unshown supporting means.

By combining the fixing roller40and the pressing roller41each having the layer structure as described above, the parting property against a sharp-melt toner can be further enhanced even in the case where a so-called sharp melt toner such that the toner is abruptly melted at a certain temperature or more, for example. Further, at not only the surface of the fixing roller40but also the surface of the pressing roller41, RTV or LTV (low-temperature vulcanizing) silicone rubber having a high toner parting effect is used, whereby it is possible to meet fixing of double-side images.

In order to control the fixing temperature, a thermistor42ais provided in contact with the surface of the fixing roller40, and a thermistor42bis provided in contact with the surface of the pressing roller41. The thermistors42aand42bare included in the driven portion506of the above-described control system. The temperature control of the fixing roller40and the pressing roller41can be carried out by a temperature adjusting means constituted by the above-described CPU500and a software thereof, for example.

This temperature adjusting means carries out the temperature control of the fixing roller40and the pressing roller41by adjusting electric power supplied to the halogen heaters40aand41ainside the core metals40b,41bdepending on detection values of the thermistors42aand42b, for example. In that case, the electric power supplied to the halogen heater40ainside the core metal40bis adjusted so that a surface temperature of the fixing roller40converges to a target temperature (about 165° C.), for example. Further, as regards the pressing roller41, the electric power supplied to the halogen heater41ainside the core metal41bis adjusted so that a surface temperature of the pressing roller41converges to a target temperature (about 140° C.).

An optimum heating quantity for melting the toner image on the sheet P is different depending on a thickness or a weight per unit area (basis weight) of the sheet P, and therefore the CPU500changes the target temperature for temperature adjustment of the fixing roller40depending on a species of the sheet P. However, it takes a time from a change of the target temperature until the surface temperature of the fixing roller40converges to the target temperature, and therefore the target temperature is set at a high value correspondingly to the sheet P requiring a large heat quantity, so that the sheets P of many species are heated at the same temperature. In this case, with respect to the sheet P not requiring so large heat quantity, the heat quantity becomes excessively large, so that a hot offset phenomenon such that the melted toner is transferred from the sheet P onto the fixing roller40is liable to occur.

The cleaning device600feeds the cleaning sheet61(cleaning web), wound in a roll shape by an unshown driving means, in an arrow direction59while winding up the cleaning sheet61little by little in synchronism with the image forming process. A cleaning portion contributing to the cleaning of the cleaning sheet61is contacted to a member-to-be-cleaned by a web roller63. Incidentally, in this embodiment, the cleaning sheet61is not directly contacted to the fixing roller40, but for example, a collecting roller62as a collecting member or a rotatable collecting member for collecting a deposited foreign matter is provided. This collecting roller62contacts the cleaning sheet61toward the web roller63and is disposed so as to rotate in contact with the fixing roller40, so that the cleaning sheet61is rubbed with the collecting roller62. Thus, the collecting roller62functions so that the cleaning sheet61and the fixing roller40are indirectly contacted to each other.

Incidentally, depending on a combination of materials, a structure such that the cleaning sheet61is directly contacted to the fixing roller40which is the member-to-be-cleaned may also be employed. However, in such a structure, there is also a possibility that the fixing roller40is damaged by the cleaning sheet61itself or the foreign matter deposited on the cleaning sheet61and thus a stripe is formed on a recording image. On the other hand, according to a structure in which the cleaning sheet61is indirectly contacted via the collecting roller62, it is possible to avoid the lowering in recording image quality as described above.

FIG. 12andFIGS. 3 to 9show an example of a structure of the cleaning device600disposed together with the fixing device9in this embodiment. The cleaning device600includes, e.g., an exchangeable cleaning unit60. Incidentally, as regards the cleaning unit60portion, there is a case that from a mounting and demounting structure, for example, as a name regarding supply and selling, a designation such as a “cleaning cartridge” or simply a “cartridge” is used in some instances. In the following, description will be made subsequently using the designation of the “cleaning unit”. Incidentally, in the following, materials of respective mechanical members constituting the fixing device9and the cleaning device600can be selected by the person skilled in the art from arbitrary materials such as metals and plastics depending on specifications or the like of operations of the respective members.

Incidentally, the fixing device9in which the cleaning device600is disposed corresponds to a heating (process) device of the image forming apparatus of an electrophotographic type, for example. However, the cleaning device600and the mounting and demounting mechanism thereof which are described below in detail can be similarly carried out even in the case where the device and the mechanism are provided along with the heating device disposed as a gloss improving device or the like.

First, usingFIG. 12, in the cleaning device600in this embodiment, an example of a structure for fixing (locking) or fixing-releasing (unlocking) the cleaning unit60will be described.

As shown inFIG. 12, the cleaning unit60includes, for example, left and right side plates60aand60band a top plate60c, and by these, a frame of the cleaning unit60is constituted. The cleaning sheet61is mounted and charged, in the cleaning unit60, in a state of being wound up by the web supplying roller61a, and one end thereof is pulled out from an outside thereof, so that the cleaning sheet61is stretched and mounted so as to be wound up by a web cleaning unit roller61b. Further, at an intermediary portion between the web supplying roller61aand the web cleaning unit roller61b, the cleaning sheet61is stretched and extended around the web roller63pressed (urged) against the collecting roller62by an urging mechanism (FIG. 3) described later. By this web roller63, a cleaning portion of the cleaning sheet61is slid on the fixing roller40(via the collecting roller62).

The web supplying roller61a, the web cleaning unit roller61band a shaft63aof the web roller63around which the cleaning sheet61is wound and mounted are shaft-supported between particularly the left and right side plates60aand60b. Of these, for example, an end portion where at least a cut-away portion of the web cleaning unit roller61bis exposed from the left side plate60aand is constituted so that the end portion is capable of engaging with a driving shaft of an unshown motor for winding up the web.

Further, inside the left side plate60aof the cleaning unit60, a remaining amount detecting arm70for detecting the remaining amount of the cleaning sheet61is supported rotatably via a shaft70d. The remaining amount detecting arm70includes a lever70bcontacting the cleaning sheet61and a lever70ainterrelating the photo-interrupter with a remaining amount detecting flag described later.

An entirety of the above-described cleaning unit60is mounted at a predetermined mounting position between attitude control plates90and90positioned outside the left and right side plates60aand60b. In this embodiment, a locking mechanism for fixing or fixing-releasing the cleaning unit60in either of a locked state in which the cleaning unit60is fixed in this predetermined positional relationship or an unlocked state in which the cleaning unit60is fixing-released is provided. That is, on the top plate60cof the cleaning unit60, the dial-shaped web locking knob73capable of performing a rotation (movement) operation is provided, and with a lower surface of the web locking knob73, one end of the locking arm74is linked. By performing the rotation operation of the web locking knob73, free ends74aand74bof the locking arm74can be moved in an expansion and contraction direction shown by arrows inFIG. 12.

In the case where the web locking knob73is rotated (moved) to the position ofFIG. 12, as shown in the figure andFIG. 6, the free ends74aand74band outer locking holes76aand76b, having, e.g., a rectangular hole shape, provided in the attitude control plates90and90. By this, the cleaning unit60is locked (fixed) at the predetermined mounting position in the cleaning device600. Incidentally, in order to carry out positioning of the cleaning device600at the mounting position described above, for example, a guiding groove may also be provided, as desired, between the left and right side plates60aand60band the attitude control plates90and90. Further, the attitude control plates90and90inFIG. 12are functionally displayed, and may also use a shape different from that inFIG. 12in actuality (for example,FIG. 4described later).

The attitude control plates90and90of the cleaning unit60are shaft-supported by the fixing device9via a unit rotation supporting portion90a. The cleaning unit60may only be required to be constituted so that at least the cleaning unit60can be mounted and demounted as regards a purpose such as maintenance, and the attitude control plates90and90may only be required to be assembled with the fixing device9side with the above-described shaft-supporting relationship. In that meaning, the attitude control plates90and90may also be considered as, rather than a part of the cleaning device600, a portion in the image forming mechanism (the fixing device9as an example of the heating device in this embodiment) side to which the cleaning unit60is mounted and from which the cleaning unit60is demounted.

In a normal image forming operation period, the cleaning unit60is put in the fixed (locked) state at the predetermined position (or with a predetermined positional relationship with the image forming mechanism) by the above-described locking arm74. In this locked state, the attitude control plates90and90are swing (rotation)-operated by the controller (CPU500) via the unit rotation supporting portion90a. Depending on this, when the cleaning unit60is in a state in which the cleaning unit60is properly fixed (locked) by the attitude control plates90and90, a portion acting on cleaning (portion) of the cleaning unit60is operated so as to be contacted to and spaced from an object-to-be-cleaned. A mechanism for swing (rotation)-operating the attitude control plates90and90is an operating cam91and a unit pressing spring96which are described later byFIG. 3. InFIG. 12, a direction in which the unit pressing spring96urges the attitude control plates90and90and an operating direction of the operating cam91are shown by arrows to which corresponding reference symbols (numerals) are added.

On the other hand, when the dial-shaped web locking knob73constituting the above-described locking mechanism is rotated as in, for example,FIG. 5, engagement between the free ends74aand74bof the locking arm74and the outer locking holes76aand76b(FIG. 12) is eliminated (disengaged). By this, the cleaning unit60is in the unlocked (fixing-released) state. In this unlocked (fixing-released) state, it becomes possible to perform a maintenance operation such that the cleaning unit60is demounted and the cleaning sheet61is exchanged or that the entirety of the cleaning unit60is exchanged as desired.

In this embodiment, the locking mechanism consisting of the web locking knob73and the locking arm74an the interrelating mechanism for interrelating the remaining amount detecting mechanism for detecting the remaining amount of the cleaning sheet61. As regards this interrelating mechanism, description will be described later in detail, and in the following, by making reference toFIG. 3and later, principally in the fixed (locked) state of the cleaning unit60, a constitution and operation of the cleaning device600will be described.

FIG. 3shows, from a side, a schematic structure of the cleaning device600in the fixed (locked) state of the cleaning unit60. Further,FIG. 4shows, as a perspective view, the entirety of the fixing device9being in the state in which the cleaning unit60of the cleaning device600is fixed (locked). The state ofFIG. 4is equal to the fixed (locked) state of the cleaning unit60shown inFIG. 12described above, but portions around the outer locking holes76aand76bfor the attitude control plates90and90can be formed in an annular shape as shown in, e.g.,FIG. 4as desired. Further, inFIG. 4, the unit pressing springs96and96for urging the attitude control plates90and90from above are not illustrated. However, the unit pressing springs96and96may employ an arbitrary structure such that the unit pressing springs96and96are appropriately disposed at an upper portion of the fixing device9or that the springs96and96are disposed inside the casing of the fixing device9and are disposed so as to press projections formed so as to extend to outsides of the attitude control plates90and90, for example.

Here, a structure and a function of the cleaning device600will be described principally usingFIG. 3.FIG. 3shows a schematic structure of an upper surface of the fixing roller40of the fixing device9and the cleaning unit60positioned above the upper surface of the fixing roller40.FIG. 3schematically illustrates a state in which the cleaning unit60is fixed (locked) to the attitude control plates90and90by the above-described locking mechanism. For this reason, inFIG. 3, the left and right side plates60aand60b, the top plate60cwhich are in the cleaning unit60side, and the web locking knob73and the locking arm74which are provided thereon, and the like are omitted from illustration.

In the illustrated state ofFIG. 3, the cleaning sheet61contacts the collecting roller62via the web roller63, and the fixing roller40is cleaned by the cleaning sheet61via the collecting roller62described above. An object to be collected and cleaned from the fixing roller40is, e.g., the offset toner transferred from the sheet P on the fixing roller40as described above.

The cleaning sheet61is charged in a state in which the cleaning sheet61is wound up by the web supplying roller61awhich is an example of a first winding-up member, and one end thereof is pulled out from an outside and is stretched and mounted so as to be wound up by the web cleaning unit roller61bwhich is an example of a second winding-up member.

At an intermediary portion between the web supplying roller61aand the web cleaning unit roller61b, the cleaning sheet61is stretched and wound around the web roller63pressed toward the collecting roller62by a mechanism described later. The cleaning sheet61is pressed against the collecting roller62by the web roller63and cleans the collecting roller62(the fixing roller40via the collecting roller62).

The cleaning sheet61is a cleaning web constituted by a material such as a nonwoven cloth, for example. The winding-up of the cleaning sheet61by the web cleaning unit roller61bis carried out little by little (on a small amount basis), for example, by control of the CPU500(described later) in synchronism with the image forming process. The cleaning sheet61is pressed against the web roller63and cleans the collecting roller62while sliding on the collecting roller62at a portion thereof with respect to a movement direction.

Both ends of the web supplying roller61a, the web cleaning unit roller61band the web roller63which are described above are shaft-supported by the left and right side plates60aand60bof the cleaning unit60as described above. A mechanism for urging and supporting the shaft63aof the web roller63will be described later.

Further, as mentioned inFIG. 12, the (left and right (both) side) attitude control plates90constituting a part of the cleaning unit60are swing (rotation)-supported by the unit rotation supporting portion90a. Further, the attitude control plates90are pressed by the unit pressing spring96from above in an opposite side from the unit rotation supporting portion90a, and lower edges thereof are pressed against the operating cam91. The operating cam91is disposed at a corresponding position of the inside of the fixing device9, for example.

The control device, for example, the CPU500described above can switch the contact and separation (spacing) of the cleaning sheet61relative to the collecting roller62by rotation of the operating cam91.

For example, at timing when cleaning of the fixing roller40after a single image forming process (fixing process) is needed, the CPU500lowers the attitude control plates90(and90) via the operating cam91and can contact the web roller63to the collecting roller62. In this state, by rotationally rotating the fixing roller40, it is possible to remove the toner collected, from the fixing roller40on the collecting roller62, by the cleaning sheet61. Further, the CPU500actuates motor (not shown), included in the driven portion506, at a frequency described later, so that the cleaning sheet61contacting the collecting roller62is gradually wound up, in an arrow59direction. As a result, before the cleaning sheet61is partly saturated with the toner, a fresh unused cleaning portion of the cleaning sheet61is contacted to the collecting roller62, so that the fixing roller40can be cleaned via the collecting roller62.

Further, during image formation, particularly in a period in which the fixing device9carries out an intended fixing process, the CPU500can raise the attitude control plates90(and90) via the operating cam91as desired. By this, the influence on the image forming process can be reduced. Incidentally, a similar interrelating mechanism by the cam is also provided for the collecting roller62.

A fresh (new) cleaning sheet61is mounted on the web supplying roller61ain a roll state. A terminal portion of the cleaning sheet61is rotatable about the web supplying roller61a, and a roll of the cleaning sheet61is rotated with pulling-out of the cleaning sheet61. A starting portion of the cleaning sheet61engages with the web cleaning unit roller61b. At one end portion of the web cleaning unit roller61b, the motor (included in the above-described driven portion506: not shown) for winding-up the cleaning sheet61is provided.

Here, description regarding materials or the like of respective portions constituting the cleaning device600will be described.

The web roller63ais disposed with the shaft63, as the center thereof, formed of a high-rigidity metal (SUS 303) in order to suppress flexure when contacting the collecting roller62. In the web roller63, on the shaft63a, a silicone sponge which is easily flexed and which has a heat-resistant property and a diameter of 30 mm is wound in order to enhance a broad nip width with the collecting roller62to enhance cleaning power. Further, it is possible to prevent toner deposition by coating the surface of the silicone sponge with a 100 μm-thick PFA tube.

The shaft63aof the web roller63is supported rotatably and slidably in an elongated hole90bprovided in the attitude control plate90. A sliding direction in the elongated hole90bis a direction perpendicular to a tangential line between the web roller63and the collecting roller62. The shaft63aof the web roller63is pressed in a direction of the collecting roller62by a web roller pressing spring92elastically mounted between pins (not shown) provided on the attitude control plate90, for example. An arrangement position of the web roller pressing spring92is not illustrated also in other figures in detail, but may be provided either outside or inside the attitude control plate90.

The collecting roller62is a cylindrical member formed of SUS 303 in an outer diameter of 20 mm. In the case where the toner is scraped off from the sheet P to effect onto the fixing roller40, an offset toner is collected by the cleaning sheet61after being collected by the collecting roller62. The collecting roller62is disposed so as to be always contacted to the surface of the fixing roller40also, e.g., in a period other than during image formation for the purpose of collecting a deposited matter.

The collecting roller62is rotated by the fixing roller40with rotation of the fixing roller40. The collecting roller62is rotatable by being supported at both end portions by ball bearings supported movably in a direction of the fixing roller40.

The collecting roller62is pressed toward the fixing roller40by a collecting roller pressing spring93, a collecting roller pressing arm94and a collecting roller pressing cam95. The collecting roller pressing spring93is fixed at one end to the end portion of the collecting roller62, and the collecting roller pressing spring93is fixed at the other end to the collecting roller pressing arm94. The control device, for example, the CPU500causes the collecting roller pressing cam95to rotate, whereby the collecting roller pressing arm94is rotated about a rotation shaft94a, so that an operating length of the collecting roller pressing spring93can be changed.

By this, the CPU500can variably change a pressure of the collecting roller62to the fixing roller40. A variable range of the pressure of the collecting roller62to the fixing roller40is about 0 N to 80 N, for example. The CPU500is capable of variably controlling the pressure of the collecting roller62to a proper value depending on the image forming sequence or the cleaning operation by the cleaning device600described above.

For example, in a period in which the cleaning operation is not needed, the CPU500controls the pressure so that the pressure of the collecting roller62is made a weak value (e.g., in the neighborhood of 0 N) in the above-described variable pressure range by the collecting roller pressing cam95, in synchronism with the raising of the attitude control plates90(and90). Further, at timing when the cleaning operation is performed, the CPU500controls the pressure so that the pressure of the collecting roller62is made a weak value (e.g., in the neighborhood of 80 N) in the above-described variable pressure range by the collecting roller pressing cam95, in synchronism with the lowering of the attitude control plates90(and90). Incidentally, the pressure control, of the collecting roller62, carried out via the collecting roller pressing cam95is not necessarily carried out in the mode as described above, and the person skilled in the art may change arbitrarily as needed.

Here, a mechanism for remaining amount detection in which a remaining amount of the cleaning sheet61of the cleaning device600is detected will be described. The position, where the remaining amount detecting arm70contacts the cleaning sheet61, described inFIG. 12is shown by the same reference symbol inFIG. 3(ditto forFIG. 2).

FIGS. 7 to 9show an example of a structure of a remaining amount detecting mechanism including the remaining amount detecting arm70.FIGS. 7 to 9show, as perspective views from a rear side (from a right side ofFIGS. 3 and 2), a structure around the remaining amount detecting arm70shown inFIGS. 12, 5 and 6and the like.

In this embodiment, the control device, for example, the CPU500causes the cleaning sheet61to move in a movement direction by a predetermined amount for each of times of image formation on a predetermined number of recording material sheets and carries out control so that the cleaning sheet61is wound up gradually in a direction of the arrow59(FIG. 3). Specifically, a web feeding amount per (one) sheet P of A4 in size fed by long edge feeding is about 0.5 mm/sheet, for example. Or, control such that the cleaning sheet61is sent by about 5 mm for each image formation on 10 sheets.

At a portion, in the neighborhood of an end edge of the cleaning sheet61, where a small remaining amount should be detected, a cut-away portion69is provided as shown inFIG. 9. The remaining amount detecting arm70supported rotatably around the shaft70dis rotationally urged in arrow directions ofFIGS. 7 to 9by a spring70c.

For this reason, in a state in which there is a sufficient remaining amount of the cleaning sheet61, the lever70bcontacts the cleaning sheet61and the remaining amount detecting arm70assumes an attitude as inFIG. 8(or ditto forFIG. 7). On the other hand, when the cleaning sheet61is consumed by the above-described feeding of the cleaning sheet61and the cut-away portion69reaches the position of the lever70b, the remaining amount detecting arm70assumes an attitude as inFIG. 9.

In order to read a detection state of the remaining amount detecting arm70as described above via the photo-sensor72provided as a remaining amount sensor for detecting the remaining amount of the cleaning sheet61, in this embodiment, a mechanism as described below is provided, for example. The lever70aof the remaining amount detecting arm70of the cleaning unit60shown inFIGS. 7 to 9is provided, as shown inFIGS. 12, 5 and 6and the like, so as to project to a position behind the left side plate60a.

On the other hand, in the image forming apparatus100(i.e., the fixing device9as the image heating apparatus) side, a the photo-interrupter77shaft-supported by a rotation shaft77ais provided. The photo-interrupter77includes, at one end of the rotation shaft77a, a lever77bengageable with the lever70aof the remaining amount detecting arm70and includes, at a free end of the other end of the rotation shaft77a, a light-block portion77chaving an arcuate cross-section. The photo-interrupter77is constituted so that a portion thereof in the light-block portion77cside is heavier than a portion thereof in the lever77bside with respect to, e.g., the rotation shaft77a, as a center (the center of gravity is positioned at the portion in the light-block portion77cside). Such a constitution can be realized by adjusting a length and a material of the portions of the photo-interrupter77in both sides of the rotation shaft77a. By such an arrangement of the center of gravity, the photo-interrupter77is displaced so as to assume an attitude following an engaged state of the lever77bwith the lever70aof the remaining amount detecting arm70.

Further, in the image forming apparatus100(i.e., the fixing device9as the image heating apparatus) side, the photo-sensor72for detecting the light-block portion77cis provided. The photo-sensor72is constituted by, e.g., a photo-interrupter including a light projecting portion and a light receiving portion and is capable of detecting whether or not the light-block portion77cis positioned between the light projecting portion and the light receiving portion. The detection state of the photo-sensor72can be read by the CPU500via the interface503.

When the remaining amount of the cleaning sheet61becomes small and the cut-away portion69appears at the position of the lever70bof the remaining amount detecting arm70, as shown inFIG. 9, the remaining amount detecting arm70is rotated as in an arrow by an urging force of the spring70c. By this, the lever70aof the remaining amount detecting arm70engages with the lever77bof the remaining amount detecting arm77and pushes down the lever77bas in an arrow80a. By this, the photo-interrupter77is rotated as in an arrow80b, so that the light-block portion77cmoves to a position where the light-block portion77cblocks detection light of the photo-sensor72. This detection state of the photo-sensor72is referred to as a light-blocked state (ON) in this embodiment.

On the other hand, in the case where the remaining amount of the cleaning sheet61is sufficient, the remaining amount detecting arm70is in a state ofFIG. 8. In this case, the lever70bof the remaining amount detecting arm70urged by the spring70ccontacts the cleaning sheet61and does not rotate to the extent of the state ofFIG. 9. For this reason, depending on the rotation position of the lever70aof the remaining amount detecting arm70, the lever77bof the photo-interrupter77is rotated as in an arrow79c, so that the light-block portion77cleaves the position of the photo-sensor72. For this reason, a state in which the detection light of the photo-sensor72is not blocked by the light-block portion77cis formed. This detection state of the photo-sensor72is referred to as a light-transmitted state (OFF).

The CPU500reads an output state of the detection signal of the photo-sensor72via the interface503and can recognize a state of the remaining amount of the cleaning sheet61through the light-blocked state (ON) or the light-transmitted state (OFF) which are described above. According to the above-described constitution of the remaining amount detecting means, when the detection signal of the photo-sensor72indicates the light-blocked state, the cut-away portion69of the cleaning sheet61is detected, so that the remaining amount of the cleaning sheet61can be discriminated as being small. Further, when the detection signal of the photo-sensor72indicates the light-transmitted state (OFF), the cut-away portion69is not detected, so that the remaining amount of the cleaning sheet61can be discriminated as being still sufficient.

However, in this embodiment, the photo-sensor72is used for detecting also a locked/unlocked state of the cleaning unit60through an operation of an interrelating mechanism, for interrelating the locking mechanism of the cleaning unit60with the above-described remaining amount detecting means, described later. For this reason, in this embodiment, as shown in a control procedure (FIGS. 10 and 11) described later, control for changing interpretation (discrimination) of the output state of the photo-sensor72is changed depending on detection timing, for example.

Incidentally, a distance from a starting end of the cleaning sheet61wound and mounted about the web supplying roller61ato the cut-away portion69is, e.g., about 5000 mm. Further, in order that a necessary cleaning operation is performed depending on image formation on a single sheet P and that a cleaning portion acting on the cleaning with the cleaning operation is moved, a feeding amount of the cleaning sheet61wound up by the cleaning unit roller61bis about 0.5 mm/sheet, for example. In such a dimensional distribution, after the cleaning sheet61is exchanged to a new one, when about 10000 sheets P are subjected to sheet passing (image formation), the cut-away portion69appears at the position of the remaining amount detecting arm70, and by this, a small remaining amount is detected through the light-blocked state (ON) of the photo-sensor72. Further, a length of a portion subsequent to the cut-away portion69wound and mounted about the web supplying roller61ais about 75 mm, for example. In this dimensional distribution, when the feeding amount per (one) sheet (one image formation) is 0.5 mm sheet, even after the cut-away portion69is detected, it is possible to execute cleaning necessary for image formation on about 150 sheets P.

(Detection of Locked State of Cleaning Unit)

Then, in either ofFIGS. 8 and 9, a proper mounting state in which the (free end of the) locking arm74engages with the outer locking hole76aand the cleaning unit60is locked by the attitude control plates90and90is formed (state ofFIG. 12, 6 or 4). In this embodiment, in the case where the cleaning unit60is thus in the proper mounting state in which the cleaning unit60is locked by the attitude control plates90and90, by the operation as described above, the CPU500is capable of carrying out image formation control depending on the remaining amount of the cleaning sheet61.

However, after an operation such as mounting and demounting of the cleaning unit60described later, in the case where the above-described locking (fixing) operation is erroneously performed and the locked state is not formed (or is insufficient), the cleaning unit60cannot be properly operated. For example, in a (unlocked) state in which the cleaning unit60is not locked by the attitude control plates90and90, even when the CPU500operates the attitude control plates90and90via the operating cam91, the cleaning unit60does not operate as design intent. By this, an intended cleaning operation becomes impossible, so that there is a possibility that image defect generates.

For this reason, in this embodiment, as shown at upper portions ofFIGS. 7 to 9, an interrelating mechanism for interrelating the locking mechanism consisting of the web locking knob73, the locking arm74and the like with the remaining amount detecting means consisting of the photo-interrupter77, the photo-sensor72and the like is provided.

This interrelating mechanism includes interrelating arms75provided above the photo-interrupter77in the fixing device9side. An upper portion of the interrelating arms75is shown inFIG. 4, and the interrelating arms75are disposed outside the attitude control plates90and90(and the outer locking holes76aand76b) as in the figure.

As shown inFIGS. 7 to 9, the interrelating arm75has a substantially L-(character) shape and is shaft-supported rotatably about a rotation shaft75a. The upper portion of the interrelating arm75is not only urged rightward inFIGS. 7 to 9by a spring78elastically mounted between itself and a predetermined portion in the fixing device9but also has a length in which the upper portion is engageable with a free end74aof the locking arm74. Incidentally, a spring force of the spring78is set at about 200 gf, for example.

By this, the interrelating arm75interrelates with the free end74aof the locking arm74and is controlled to an attitude ofFIG. 7orFIG. 8(andFIG. 9) depending on an interrelating state with the locking arm74.FIG. 7corresponds to an unlocked (fixing-released) state of the cleaning unit60in which the free end74aof the outer locking arm74is recessed inwardly from the locking hole76a. Further,FIG. 8andFIG. 9correspond to a locked (fixed) state of the cleaning unit60in which the free end74aof the outer locking arm74projects to an outside of the locking hole76aand engages with the interrelating arm75.

Here, in the locked (fixed) state (FIGS. 8 and 9) of the cleaning unit60, the locking arm74is pushed and rotated counterclockwisely in the figure (arrow79binFIG. 8) by the free end74aof the locking arm74and does not obstruct the operation of the photo-interrupter77. Accordingly, in the locked (fixed) state (FIGS. 8 and 9) of the cleaning unit60, the photo-interrupter assumes, as described above, the attitude corresponding toFIG. 8(with a remaining amount) orFIG. 9(with a small remaining amount) depending on the remaining amount of the cleaning sheet61. Accordingly, in this locked (fixed) state of the cleaning unit60, the CPU500is capable of detecting the remaining amount of the cleaning sheet61through the light-blocked state (ON) or the light-transmitted state (OFF) of the photo-sensor72.

On the other hand, in the unlocked (fixing-released) state (FIG. 7) of the cleaning unit60, the urging (pressing) of the free end74aof the locking arm74against the interrelating arm75is eliminated (released), so that the interrelating arm75rotates clockwisely in the figure (arrow79e). For this reason, the lever77bof the photo-interrupter77which is pressed down by a lower portion of the interrelating arm75forcedly controls the photo-sensor72so as to be in the light-blocked state (ON). In this embodiment, it is possible to detect the unlocked (fixing-released) state of the cleaning unit60through the light-blocked state (ON), of the photo-sensor72, formed by the interrelating operation as inFIG. 7.

Detection control of the locked state of the cleaning unit60by using the interrelating mechanism (interrelating portion, acting portion) shown inFIG. 7andFIG. 8(FIG. 9) will be described later in detail using a flowchart (particularlyFIG. 10)

(Mounting and Demounting of Cleaning Unit)

Here, exchange or mounting and demounting of the cleaning unit60of the cleaning device600will be described.FIG. 4shows, as a perspective view, a state in which the cleaning unit60of the cleaning device600is mounted in the fixing device9. As described above, the cleaning unit60includes the locking mechanism consisting principally of the web locking knob73and the locking arm74.

For example, when the web locking knob73is rotated to a rotation position ofFIG. 6, in interrelation with this, the free ends74aand74bof the locking arm74extend and engage with the outer locking hole76aand76bof the attitude control plates90and90swing-supported in the fixing device9side (FIGS. 8, 9 and 12). Thus, the cleaning unit60is locked (fixed) to the image forming mechanism (the fixing device9as the image heating apparatus). When the web locking knob73is rotated from this state to a rotation position ofFIG. 5, engagement of the free ends74aand74bof the locking arm74with the outer locking holes76aand76bis eliminated (disengaged), so that the cleaning unit60is unlocked (fixing-released).

In the unlocked (locking-released) state of the cleaning unit60, the cleaning unit60can be pulled out, e.g., upwardly from between the attitude control plates90and90. Thereafter, a fresh (new) cleaning unit60(for example, supplied as an exchanging or maintenance part) is mounted, and again, the cleaning unit60is locked by the above-described operation of the web locking knob73. By this, the cleaning operation as design specification of the cleaning unit60becomes possible. Incidentally, not the exchange for each of cleaning units60, a maintenance type in which the consumed cleaning sheet61is removed from the cleaning unit60and is exchanged with a fresh (new) cleaning sheet61may also be employed.

In the locked state of the cleaning unit60by the attitude control plates90and90, the attitude control of the cleaning unit60described inFIG. 3becomes possible, so that it is possible to carry out the cleaning operation as design specification. In that case, the remaining amount detecting mechanism of the cleaning sheet61operates as shown inFIGS. 8 and 9, and in the case where the cleaning sheet61becomes small in remaining amount, the CPU500of the control system can detect the state as the light-blocked state (ON) of the photo-sensor72. In this case, for example, as shown in control described later, an image process is permitted in number of times in which the cleaning process can be performed at a portion subsequent to the cut-away portion69of the above-described cleaning sheet61while providing warning to the effect that the remaining amount of the cleaning sheet61is small. Or, in a simple control specification, in the case where the small remaining amount of the cleaning sheet61is detected as described above, the CPU500immediately carries out control so as to prohibit further image formation (sheet passing).

On the other hand, in the case where the cleaning unit60is in the unlocked (unfixed) state (or ditto for a state in which the cleaning unit60is demounted from the cleaning device600), the interrelating mechanism of the locking mechanism of the cleaning sheet61with the remaining amount detecting mechanism is in the state ofFIG. 7. In this state ofFIG. 7, naturally, the attitude control of the cleaning unit60described inFIG. 3is impossible, and the cleaning operation as design specification is impossible, so that if the image formation is forcedly carried out, there is a possibility that an image defect generates.

However, in this embodiment, in the state ofFIG. 7, the light-blocked state (ON) of the photo-sensor72is forcedly formed through the interrelation of the interrelating arm75with the photo-interrupter77irrespective of the remaining amount of the cleaning sheet61. In the case where the small remaining amount of the cleaning sheet61is detected, when control specification in which the CPU500immediately prohibits the image formation (sheet passing), further additional mechanism and control are not needed, and the image formation (sheet passing) can be prohibited in this state. Accordingly, it is possible to reliably avoid a problem such as a lowering in recording image quality due to improper cleaning of the heating member (fixing roller40).

Or, in the control specification in which the image formation effected in the number of times in which the cleaning process can be performed at the portion subsequent to the cut-away portion69of the cleaning sheet61is permitted as described above, separation and division of the control as shown inFIGS. 10 and 11described later are carried out. By effecting the control as shown inFIGS. 10 and 11described later, it is possible to properly carry out an output of warning information and prohibition (or permission) of image formation.

As described above, according to this embodiment, the interrelating mechanism for interrelating the locking mechanism of the cleaning unit60with the photo-interrupter77displaced depending on the remaining amount of the cleaning sheet61is provided. This interrelating mechanism causes the photo-sensor72as a remaining amount sensor to output the detection signal indicating the small remaining amount state of the cleaning sheet61in the unlocked state of the cleaning unit60or an unmounted state of the cleaning unit60in the cleaning device600. Further, in the locked state of the cleaning unit60, the interrelating mechanism causes the photo-sensor72to output the detection signal indicating the remaining amount of the cleaning sheet61detected via the photo-interrupter displaced depending on the remaining amount of the cleaning sheet61.

Accordingly, the image formation (sheet passing) can be permitted in the case where the cleaning unit60is normally mounted and is in locked (fixed) state and only in a state in which there is a sufficient remaining amount. By this, a lowering in image quality (or a breakdown of the mechanism) generating in the case where the cleaning unit60is not normally mounted due to an operation error of a user or the like can be prevented, so that an image forming performance with a high image quality can be maintained with the cleaning process as design specification.

Further, according to this embodiment, the photo-sensor72can be used for both of the remaining amount detection of the cleaning sheet61and the detection of the locked (fixed) state of the cleaning unit60. For this reason, it is possible to simplify the control circuit and to reduce the number of circuit parts, so that it is possible to realize space saving of the image forming apparatus100by a simple and inexpensive constitution.

(Control Example Relating to Cleaning Unit)

In the control specification in which the image formation effected in the number of times in which the cleaning process can be performed at the portion subsequent to the cut-away portion69of the cleaning sheet61is permitted, the control as shown inFIGS. 10 and 11described later is carried out. In this case, separation and division of the control as described below are carried out between after a main switch of the image forming apparatus100is turned on and after the opening and closing of the door81detected by the sensor82(FIG. 11) and the normal image forming period other than it (FIG. 10). By this, even in a constitution in which only a single photo-sensor72as described above is used, it is possible to combine the remaining amount detection of the cleaning sheet61with the detection of the locked (fixed) state of the cleaning sheet61with improved appearance.

FIGS. 10 and 11show a control procedure of the image forming apparatus100executed by the CPU500as the control device, for example. The illustrated procedure in the figure can be described as a control program to be executed by the CPU500, and the control program is stored in advance in, e.g., the ROM501or the external storing device504.

FIG. 10shows the control in an operation (normal operation) period in which a normal image forming process is carried out. Incidentally, this normal operation period ofFIG. 10is not started until in the control carried out after the main switch of the image forming apparatus100is turned on and after the opening and closing of the door81detected by the sensor82, image formation permission is made (S307inFIG. 11).

In the normal operation period, the locked (fixed) state of the cleaning unit60has already been confirmed by the control ofFIG. 11described later, and as described inFIGS. 8 and 9, the CPU500can detect the remaining amount of the cleaning sheet61by the output of the photo-sensor72.

In the normal operation period ofFIG. 10, when the photo-sensor72changes from the light-transmitted state to the light-blocked state (ON) (YES of step S301), for example, “Warning of small cleaning web remaining amount” is outputted by a display device of the operating panel505or by a voice outputting device (step S302). This “Warning of small cleaning web remaining amount” is a warning message such that, e.g., “Cleaning sheet61is used up soon”, and is outputted from the operating panel505by way of character display, synthesized voice or the like.

Subsequently, a counter provided in a nonvolatile (EEP) ROM region provided at a part of, e.g., the RAM502or the ROM501is started (step S303). In this embodiment, (also) after the small remaining amount state of the cleaning sheet61is detected, the control is carried out so that a predetermined number of times of the image formation is permitted, but this counter is used for counting the number of times of the image formation up to the predetermined number of times (count upper-limit threshold). As regards this counter, the CPU500increments the counter one by one every image formation on a single sheet, and the count upper-limit threshold can be about 150 (sheets or times) when a value corresponding to a dimension of the cleaning sheet61subsequent to the above-described cut-away portion69is employed. In this embodiment, as the count upper-limit threshold,100(sheets or times) allowing the counter leeway than 150 (sheets or times).

The normal image formation control is executed in a loop period of step S304, but during the period, the CPU500appropriately outputs the warning message of the above-described step S302. Then, the light-blocked state of the photo-sensor72continues, and therefore when the counter started in the step S303reaches the above-described upper-limit threshold (100 sheets or times), transfer to step S305generates. In the step S305, the CPU500causes the operating panel to display “Cleaning web exchange instruction” and stops further image formation (step S305).

On the other hand, the CPU500carries out control as inFIG. 11in initialization after the main switch of the image forming apparatus100is turned on and after the opening and closing of the door81detected by the sensor82(FIG. 11).

For example, when “Warning of small web remaining amount” or “Web exchange instruction” is displayed by the control ofFIG. 10, the user (or service person) performs exchange (mounting and demounting) operation of the cleaning unit60depending on this display. The control ofFIG. 11is effected by the purpose of discriminating whether or not in this exchange (mounting and demounting) operation of the cleaning unit60, the cleaning unit60is properly exchanged with a new one and the mounting of the cleaning unit60is performed with reliability.

Here, when the cleaning unit60is demounted, it is general rule that the demounting is performed after the door81is opened and closed and the fixing device9is pulled out or after the main switch of the apparatus is turned off. Accordingly, the control ofFIG. 11is executed in initialization after the main switch of the image forming apparatus100is turned on or after the opening and closing of the door81detected by the sensor82.

In step S306ofFIG. 11, when the CPU500detects a phenomenon such as the initialization after the main switch of the image forming apparatus100is turned on or the detection of the opening and closing of the door81by the sensor82(step S306), the following control is carried out.

First, the output state of the photo-sensor72is checked (step S301) and when the photo-sensor72is in the light-transmitted state (OFF), the procedure goes to step S307and the image formation is permitted. By this, the control of the image forming apparatus100can go to the normal operation control shown inFIG. 10.

On the other hand, in the step S301, in the case where the photo-sensor72is in the light-blocked state (ON), the CPU500discriminates that at least the cleaning unit60is not in a proper state and immediately prohibits the image forming process in step S308. Incidentally, in the case where the photo-sensor72is in this detection state, according to the constitutions (FIG. 7toFIG. 9) of the above-described interrelating mechanism, the case where the cleaning unit60is unlocked (is in an unmounted state or is not in a normal mounted state) is included. Further, also the case where the cleaning unit60is in the locked state and the remaining amount of the cleaning sheet61is small is included.

Therefore, in the case where the image forming process is immediately prohibited in the step S308, the warning message such that, for example, “Check remaining amount of cleaning sheet or check mounted state of cleaning sheet” is outputted from the operating panel505. That is, both of discrimination that the locking mechanism is in the unlocked state and discrimination that the remaining amount of the cleaning sheet is small are outputted as the warning message.

By carrying out the control as inFIGS. 10 and 11, the cleaning unit60can be properly mounted while employing the control specification in which the image formation in the number of times in which the cleaning process can be performed at the portion subsequent to the cut-away portion69of the cleaning sheet61is permitted. Particularly, at timing of during the turning-on of the main switch or after the opening and closing of the door81of the image forming apparatus100, a constitution in which the mounting state of the cleaning unit60can be checked using the remaining amount detecting means of the cleaning sheet61via the interrelating mechanism is employed. At this timing, in advance of the normal operation, of during the turning-on of the main switch or after the opening and closing of the door81of the image forming apparatus100, when the cleaning unit60is in the unlocked state, the warning message to the effect thereof is generated, so that the cleaning unit60can be locked with reliability.

Further, in this embodiment, the image formation can be carried out using a remaining portion of the cleaning sheet61while outputting a proper warning message depending on the small remaining amount of the cleaning sheet61. By this, the portion capable of being used for cleaning the cleaning sheet61can be used efficiently. Further, in this embodiment, the warning message is outputted at timing such that the image formation effected in the number of predetermined times from the detection of the small remaining amount of the cleaning sheet61is permitted. For this reason, the user (or an administrator or the service person) can prepare for the exchange of the cleaning sheet61or the cleaning unit60with time. On the other hand, when the cleaning unit60is not properly mounted or the remaining amount of the cleaning sheet61is 0, the image formation can be prohibited, so that a problem such that image quality lowering generates due to improper cleaning can be avoided with reliability.

Incidentally, in the above, roughly two types of control were considered as the control in the case where the photo-sensor72for detecting the cut-away portion69of the cleaning sheet61via the photo-interrupter77generates a detection sensor corresponding to (comparable to) the remaining amount warning. Of these, first control permits the image forming operation (sheet passing) in the number of times in which the cleaning process can be performed at the portion subsequent to the cut-away portion69of the cleaning sheet61while outputting the warning message (to the effect that the remaining amount is small) as shown in the above-describedFIG. 10. Further, second control prohibits further image forming operation (sheet passing) in the case where the small remaining amount of the cleaning sheet61is detected as mentioned above.

However, the above-described first and second (two) control modes are not carried out particularly only exclusively, but for example, it is possible to carry out both of the control modes by providing a plurality of cut-away portions69at different positions of the cleaning sheet61. For example, a first cut-away portion69is provided at a position corresponding to a remaining amount in which cleaning relating to image formation on about 100 sheets (times), described in association withFIG. 10, from an end edge of the cleaning sheet61. Further, a second cut-away portion69is provided at a position, from the end edge of the cleaning sheet61, corresponding to a remaining amount such that cleaning relating to image formation in further number of times cannot be carried out. Then, the above-described first control is effected in detection of the first (first-time) cut-away portion69(after the cleaning unit60is exchanged), and the above-described second control is effected in detection of the second (second-time) cut-away portion69. Thus, depending on the remaining amount of the cleaning sheet61, when the remaining amount thereof is slight (small), the image formation is permitted while warning the user that exchange timing of the cleaning unit60or the cleaning sheet61approaches (first control). Then, when the remaining amount of the cleaning sheet61is finally in a state such that cleaning relating to the image formation effected in the number of further times cannot be performed, the image formation (sheet passing) is properly prohibited (second control). By this, it is possible to reliably avoid a problem such that the image quality lowering due to the improper cleaning of the fixing roller (rotatable heating member).

INDUSTRIAL APPLICABILITY

According to the present invention, there is provided an image forming apparatus in which a cleaning device is capable of achieving sufficient cleaning performance.