Image forming apparatus including a controller configured to control switching between a first mode and second mode

An image forming apparatus includes a fixing device and a controller. The fixing device includes a heating unit and a pressurizing unit. The heating unit is configured to come into contact with a recording medium, onto which an image is transferred and which is transported, so as to heat the recording medium while rotating. The pressurizing unit is configured to press the recording medium against the heating unit. The fixing device is configured to fix the image to the recording medium. The controller is configured to control switching between a first mode for fixing the image to the recording medium and a second mode for making a transport speed of a sheet member that passes through the fixing device slower than a peripheral speed of the heating unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2019-128741 filed Jul. 10, 2019.

BACKGROUND

1. Technical Field

2. Related Art

In a fixing device disclosed in JP-A-2010-246093, an external beating roller and a refresh roller are configured to be movable with respect to a fixing roller. That is, switching is performed among the following states: a state where the external heating roller is only brought into contact with the fixing roller such that the refresh roller is separated from the fixing roller (at the fixing time); a state where the external heating roller is only separated from the fixing roller such that the refresh roller comes into contact with the fixing roller (after the end of printing), and a state where the external heating roller and the refresh roller are separated from the fixing roller (home position).

SUMMARY

An image transferred onto a recording medium is fixed to the recording medium by sandwiching the recording medium between a rotating heating unit and a rotating pressurizing unit. When a large number of recording media having the same size are sandwiched between the heating unit and the pressurizing unit, edge flaws occur on the peripheral surface of the heating unit due to edges of the recording media. The edge flaws occurring on the peripheral surface may deteriorate an image quality. As a countermeasure, the fixing device of the related art uses the refresh roller that rotates by being driven by the rotating heating unit. Here, when the refresh roller is used, it is necessary to secure a space where the refresh roller is disposed in the vicinity of the heating unit.

Aspects of non-limiting embodiments of the present disclosure relate to preventing deterioration of image quality caused by edge flaws occurring on a heating unit, without securing a space where a refresh roller is disposed.

According to an aspect of the present disclosure, there is provided an image forming apparatus including a fixing device and a controller. The fixing device includes a heating unit and a pressurizing unit. The heating unit is configured to come into contact with a recording medium, onto which an image is transferred and which is transported, so as to heat the recording medium while rotating. The pressurizing unit is configured to press the recording medium against the heating unit. The fixing device is configured to fix the image to the recording medium. The controller is configured to control switching between a first mode for fixing the image to the recording medium and a second mode for making a transport speed of a sheet member that passes through the fixing device slower than a peripheral speed of the heating unit.

DETAILED DESCRIPTION

First Exemplary Embodiment

An example of an image forming apparatus according to a first exemplary embodiment of the present disclosure will be described with reference toFIGS. 1 to 11. Additionally, in each drawing, an arrow H indicates an upward-and-downward direction (that is, vertical direction) of the apparatus, and an arrow W indicates a width direction (that is, horizontal direction) of the apparatus.

(Entire Configuration of Image Forming Apparatus)

As illustrated inFIG. 11, an image forming apparatus10includes an image forming unit12that forms toner images using an electrophotographic method, a transport unit14that transports a recording medium P along a transport path16, and a manual feed tray38that is able to supply the recording medium P from the outside.

Further, the image forming apparatus10includes an image inspecting unit24that inspects an image formed on the recording medium P, an accommodating unit18that accommodates the recording medium P, and a controller28that controls each unit. Further, the image forming apparatus10includes a reverse path26in which the recording medium P with an image formed on the front page thereof is transported again toward the image forming unit12in the way that the front and back pages of the recording medium P are reversed, in order to form images on both pages of the recording medium P (duplex printing).

In the image forming apparatus10configured as described above, toner images formed in the image forming unit12are formed on the front page of the recording medium P transported along the transport path16. Further, the recording medium P on which the toner images have been formed is ejected to the outside of the apparatus through the image inspecting unit24.

Meanwhile, when an image is to be formed on the back page of the recording medium P, the recording medium P with the image formed on the front page thereof is transported along the reverse path26, and an image is formed again on the back page of the recording medium P in the image forming unit12.

As illustrated inFIG. 11, the image forming unit12includes plural toner image forming units30that form toner images in different colors, respectively, and a transfer unit32that transfers the toner images formed by the toner image forming units30onto the recording medium P. Further, the image forming unit12includes a fixing device34that fixes the toner images transferred onto the recording medium P by the transfer unit32, to the recording medium P.

Plural toner image forming units30form toner images of different colors, respectively. In the present exemplary embodiment, total four toner image forming units30are provided for yellow (Y), magenta (M), cyan (C), and black (K), respectively. Hereinafter, when yellow (Y), magenta (M), cyan (C), and black (K) do not need to be discriminated, the symbols Y, M, C, and K will be omitted.

The toner image forming units30for the different colors basically have the same configuration, except for the toner that is used by each toner image forming unit30. As illustrated inFIG. 10, each toner image forming unit30includes a rotating cylindrical image carrier40and a charger42that charges the image carrier40. Further, the toner image forming unit30includes an exposure device44that irradiates the charged image carrier40with exposure light to form an electrostatic latent image (seeFIG. 11), and a developing device46that develops the electrostatic latent image into a toner image using a developer G containing a toner. Accordingly, the toner image forming units30for the different colors form images in the respective colors, using the corresponding toners of the colors.

In addition, as illustrated inFIG. 11, the image carriers40for the different colors are in contact with a transfer belt50that travels in a circulating manner (to be described in detail later). Further, the toner image forming units30for yellow (Y), magenta (M), cyan (C), and black (K) are arranged horizontally side by side in this order from the upstream of the transfer belt50in the circulating direction thereof (see the arrow inFIG. 11).

As illustrated inFIG. 11, the transfer unit32includes the transfer belt50that is wrapped around plural rollers (reference numerals of the rollers are omitted) and circulates in the direction indicated by the arrow inFIG. 11, and primary transfer rollers52that are arranged on the opposite sides to the image carriers40for the different colors, respectively, in a state where the transfer belt50is sandwiched between the primary transfer rollers52and the image carriers40, and transfer the toner images formed on the image carriers40for the different colors onto the transfer belt50.

Further, the transfer unit32includes a winding roller56around which the transfer belt50is wrapped, and a secondary transfer roller54that is disposed on the opposite side to the winding roller56in a state where the transfer belt50is sandwiched between the secondary transfer roller54and the winding roller56, and transfers the toner images transferred onto the transfer belt50, onto the recording medium P. Further, the transfer unit32includes a driving roller58around which the transfer belt50is wrapped such that a rotating force is transmitted to the transfer belt50. In addition, a transfer nip NT is formed between the secondary transfer roller54and the transfer belt50to transfer the toner images onto the recording medium P.

In this configuration, toner images are primarily transferred onto the transfer belt50by the primary transfer rollers52in an order of yellow (Y), magenta (M), cyan (C), and black (K). Meanwhile, the toner images are transferred from the transfer belt50onto the recording medium P that is transported in a state of being sandwiched between the transfer belt50and the secondary transfer roller54. Further, the recording medium P onto which the toner images have been transferred is delivered to the fixing device34through a belt unit60to be described later.

As described above, a delivery member48includes the driving roller58, the transfer belt50, the winding roller56, and the secondary transfer roller54. The delivery member48delivers the recording medium P to the fixing device34.

As illustrated inFIG. 11, the transport unit14includes plural transport rollers that transport the recording medium P along the transport path16(reference numerals of the transport rollers are omitted), and the belt unit60that transports the recording medium P onto which the toner images have been transferred, to the fixing device34.

As illustrated inFIG. 4, the belt unit60includes an endless transport belt60a, a driving roller60band a driven roller60caround which the transport belt60ais wrapped, and an air intake unit60dthat sucks the air inside the transport belt60a.

In this configuration, the rotating driving roller60btransmits the rotating force to the transport belt60a, such that the transport belt60acirculates. Further, the air intake unit60ddisposed inside the transport belt60asucks the air. As a result, the belt unit60transports the recording medium P while causing the recording medium P to be adsorbed to the transport belt60a.

As illustrated inFIG. 11, the fixing device34is disposed downstream of the belt unit60in the transport direction of the recording medium P. The fixing device34fixes the toner images transferred onto the recording medium P, to the recording medium P, by heating and pressing the toner images. In addition, the configuration of the fixing device34will be described in detail later.

As illustrated inFIG. 11, the image inspecting unit24is disposed downstream of the fixing device34in the transport direction of the recording medium P. The image inspecting unit24is an inline sensor, and inspects an image formed on the recording medium P by irradiating the recording medium P with light and receiving the reflected light.

As illustrated inFIG. 11, the recording medium P that has passed through the image inspecting unit24is sent to the reverse path26. In the reverse path26, the recording medium P is transported in the reverse direction to the transport direction of the recording medium P (switching-back transport), such that the front and back pages of the recording medium P are reversed. Then, for the duplex printing, the recording medium P with an image formed on the front page thereof is transported along the reverse path26such that the front and back pages of the recording medium P are reversed, and is transported again toward the image forming unit12.

The manual feed tray38is openable on the lateral side of an apparatus body10of the image forming apparatus10. Accordingly, when the user places the recording medium P on the manual feed tray38, and designates the manual feed tray38, the recording medium P placed on the manual feed tray38is transported to the image forming unit12.

The accommodating unit18includes three accommodating trays20a,20b, and20cthat are able to accommodate recording media P, and delivery rollers22a,22b, and22cthat deliver the recording media P accommodated in the accommodating trays20a,20b, and20c, respectively, to the transport path16.

The recording media P may be stacked in each of the three accommodating trays20a,20b, and20c, and the accommodating trays20band20care arranged side by side in the width direction of the apparatus at the lower portion of the apparatus body10aof the image forming apparatus10. Further, the accommodating tray20ais disposed above the accommodating trays20band20c, and recording media P having a larger size than that for the accommodating trays20band20cmay be stacked in the accommodating tray20a.

The delivery rollers22a,22b, and22cdeliver the uppermost recording media P stacked in the accommodating trays20a,20b, and20c, respectively, to the transport path16.

In the present exemplary embodiment, A3-size embossed sheets S on which images are formable are stacked in the accommodating tray20a, A4-size recording media P on which images are formable are stacked in the accommodating tray20b, and B4-size recording media P on which images are formable are stacked in the accommodating tray20c. That is, the accommodating tray20aaccommodates an embossed sheet S having the maximum width up to which the image forming apparatus10can form an image. The embossed sheet S is an example of a sheet member.

Here, the “embossed sheet S” refers to a paper on which concave-convex patterns are formed, and the embossing height is, for example, 0.1 mm or more and 1 mm or lower.

In addition, the “recording medium or sheet member having the maximum width up to which an image is formable” refers to a recording medium or sheet member which is the widest to the extent that an image can be formed using the image forming apparatus10. In other words, the “recording medium or sheet member” above refers to a recording medium or sheet member which is the widest to the extent that the recording medium or sheet member can be transported using the image forming apparatus10.

Next, the fixing device34will be described. As illustrated inFIG. 4, the fixing device34includes a heating unit70that heats the recording medium P, and a pressurizing unit72that presses the recording medium P toward the heating unit70. The heating unit70and the pressurizing unit72are arranged vertically, and the heating unit70is disposed above the pressurizing unit72.

As illustrated inFIG. 4, the heating unit70includes an endless fixing belt74, a first heating roller78that heats the fixing belt74, a second heating roller80that heats the fixing belt74, and a pad member82around which the fixing belt74is wrapped. Further, the heating unit70includes a temperature sensor86that detects a temperature of the peripheral surface of the first heating roller78, a leading edge sensor84that detects a leading edge of the recording medium P which is being transported, and an upper cover90that covers the respective members from above. Further, the heating unit70includes a voltage application unit64that applies a voltage to a halogen heater disposed inside the first heating roller78and a halogen heater disposed inside the second heating roller80(FIG. 8).

The fixing belt74has an endless shape, and is formed by coating the surface of a base material made of, for example, polyamide with a fluororesin. Then, the fixing belt74is wrapped around the first heating roller78, the second heating roller80, and the pad member82, in a posture in which the lower portion of the fixing belt74becomes a vertex of a triangle. The fixing belt74is an example of a heating unit.

The pad member82is disposed below the first heating roller78and the second heating roller80, and the lower vertex portion of the fixing belt74is wrapped around the pad member82. Further, the pad member82extends in the depth direction of the apparatus, and has a rectangular cross section.

In addition, the pad member82is attached to frame members (not illustrated) at both end portions thereof in the depth direction of the apparatus.

In this configuration, the pad member82receives a nip load from a pressure roller102that makes up the pressurizing unit72as described later, such that a nip portion N is formed between the fixing belt74and the pressure roller102.

In addition, the distance along the transport path16from the nip portion N to the portion where the secondary transfer roller54and the transfer belt50are in contact with each other (L01inFIG. 4) is shorter than the longitudinal length of the recording medium P having the minimum size on which an image is formable by the image forming apparatus10.

The first heating roller78is disposed above a one-side area from the pad member82in the width direction of the apparatus (left-side area inFIG. 4), and the axial direction thereof is directed toward the depth direction of the apparatus. In addition, the first heating roller78includes the halogen heater inside. Further, the first heating roller78is rotatably attached to frame members (not illustrated) at both end portions thereof in the depth direction of the apparatus.

The second heating roller80is disposed above the other-side area from the pad member82in the width direction of the apparatus (right-side area inFIG. 4), and the axial direction thereof is directed toward the depth direction of the apparatus. In addition, the second heating roller80includes the halogen heater inside. Further, the second heating roller80is attached to frame members (not illustrated) at both the end portions thereof in the depth direction of the apparatus, and rotates by a rotating force transmitted from a driving source.

In this configuration, when the second heating roller80rotates, the fixing belt74circulates in the direction of the arrow R1inFIG. 4in a state of maintaining its posture. Further, the first heating roller78rotates by being driven by the circulating fixing belt74.

In addition, when the voltage application unit64applies a voltage to the halogen heaters, the temperatures of the first heating roller78and the second heating roller80increase. Further, the temperature of the fixing belt74increases by the increase in temperatures of the first heating roller78and the second heating roller80.

As a result, the fixing belt74comes into contact with a recording medium P, onto which an image is transferred and which is transported, so as to heat the recording medium P, while rotating.

The leading edge sensor84is disposed downstream of the nip portion N in the transport direction of the recording medium P above the transport path16, and detects the leading edge of the recording medium P that is being transported.

The upper cover90is disposed so as to cover the area above the fixing belt74from above, and extends in the depth direction of the apparatus. In addition, the cross section of the upper cover90taken along the plane orthogonal to the depth direction of the apparatus has a U shape that opens downward.

In this configuration, the upper cover90prevents the upward movement of air heated by the increase of the temperature of the fixing belt74, so that the heat of the fixing belt74does not escape upward.

As illustrated inFIG. 4, the pressurizing unit72includes the pressure roller102that presses the recording medium P against the fixing belt74, and movement units106that move the pressure roller102in a direction in which the pressure roller102approaches or is separated from the fixing belt74, and a lower cover110that covers the respective members from below.

The pressure roller102is disposed on the opposite side to the pad member82such that the fixing belt74is sandwiched between the pressure roller102and the pad member82, and the axial direction thereof is directed toward the depth direction of the apparatus. The pressure roller102is formed by coating the outer periphery of a cylindrical roller body (not illustrated) made of, for example, aluminum with an elastic layer made of silicone rubber. In addition, a separation layer made of, for example, a fluorine-based resin is formed on the peripheral surface of the elastic layer. The pressure roller102is an example of a pressurizing unit.

Further, the pressure roller102is attached to the movement units106at both end portions thereof in the depth direction of the apparatus, and when a rotating force is transmitted from a driving source (not illustrated), the pressure roller102rotates in the direction of the arrow R2inFIG. 4.

A pair of movement units106is arranged at both ends of the pressure roller102, and formed by combining well-known mechanical components with each other.

In this configuration, the movement units106move the pressure roller102in the direction in which the pressure roller102approaches or is separated from the portion of the fixing belt74that is wrapped around the pad member82. Specifically, when the fixing device34fixes toner images to the recording medium P, the movement units106move the pressure roller102to a contact position where the recording medium P that is being transported in contact with the fixing belt74is pressed against the fixing belt74(see the solid line inFIG. 4). Meanwhile, when the fixing device34is in a non-operating state, and when the temperature of the fixing belt74is increased to a threshold, the movement units106move the pressure roller102to a separation position where the pressure roller102is separated from the fixing belt74(see the double chain line inFIG. 4). When the movement units106move the pressure roller102as described above, the pressing force with which the pressure roller102presses the recording medium P against the fixing belt74changes. Accordingly, the movement units106function as pressure adjustment units that adjust the strength of the pressing force with which the pressure roller102presses against the fixing belt74.

In addition, when the fixing belt74circulates in a state where the pressure roller102is disposed at the separation position, the rotating force of the rotating second heating roller80is transmitted to the fixing belt74. Meanwhile, when the fixing belt74circulates in a state where the pressure roller102is disposed at the contact position, the rotating force of the second heating roller80is released, and the rotating force of the rotating pressure roller102is transmitted to the fixing belt74.

The lower cover110is disposed so as to cover the pressure roller102and the movement units106from below, and extends in the depth direction of the apparatus. In addition, the lower cover110has a body110aand a plate-shaped guide110bthat guides the recording medium P along the transport path16.

The cross section of the body110ataken along the plane orthogonal to the depth direction of the apparatus has a U shape that opens upward.

The guide110bcovers a portion of the opening of the body110adownstream of the nip portion N in the transport direction of the recording medium P. In addition, the plate surface of the guide110bis inclined such that one end of the guide110bin the width direction of the apparatus is lower than the other end thereof when viewed from the depth direction of the apparatus.

In this configuration, in a state where the pressure roller102is disposed at the contact position, the leading edge of the recording medium P sent from the nip portion N of the fixing device34comes into contact with the guide110bfrom above, and the recording medium P is guided along the transport path16, as illustrated inFIG. 3.

Here, the leading edge of the recording medium P sent from the nip portion N comes into contact with the guide110bfrom above. In other words, the guide110bsupports the leading edge of the recording medium P from below. Accordingly, as illustrated inFIG. 6, even in a state where the pressure roller102is disposed at the separation position, the recording medium P comes into contact with the guide110b, so that the contact between the recording medium P and the fixing belt74is maintained. In this way, the guide110bfunctions as a contact maintaining unit that maintains the contact between the recording medium P and the fixing belt74.

As illustrated inFIG. 8, the controller28controls each unit provided in the image forming apparatus10. Further, the controller28controls switching between a first mode for fixing a toner image to the recording medium P and a second mode for restoring the fixing belt74having edge flaws caused by the edges of the recording media P. The control of each unit by the controller28will be described later together with the operation thereof.

The image forming apparatus10includes a counter62that counts the number of recording media P on which images have been formed, for each size (seeFIG. 8).

(Operation of Image Forming Apparatus10)

Next, operation of the image forming apparatus10will be described based on the flowchart illustrated inFIG. 7.

In a state where the image forming apparatus10is installed at an installation place and is in the non-operating state, the pressure roller102is disposed at the separation position where the pressure roller102is separated from the fixing belt74, and the respective units of the image forming apparatus10are stopped, as illustrated inFIG. 5.

When the image forming apparatus10operates such that a process for a printing job is started, the controller28operates each unit in the first mode for forming and fixing toner images onto the recording medium P, in step S100illustrated inFIG. 7. Specifically, toner images are formed in the image forming unit12illustrated inFIG. 11. Further, in the fixing device34illustrated inFIG. 4, the voltage application unit64applies a voltage to the halogen heater inside the first heating roller78and the halogen heater inside the second heating roller80, such that the second heating roller80transmits the rotating force to the fixing belt74. Then, the temperature sensor86detects the temperature of the peripheral surface of the first heating roller78, and when the temperature of the first heating roller78becomes equal to or higher than a threshold, the movement units106move the pressure roller102disposed at the separation position to the contact position. Additionally, the “printing job” refers to a process unit for a printing operation indicated by one printing instruction.

Further, the controller28controls the transport unit14, and operates the transport rollers and the belt unit60to fix the toner images to the recording medium P. Specifically, the transport rollers that make up the transport unit14transport the recording medium P accommodated in the accommodating unit18along the transport path16, and the toner images are transferred onto the recording medium P that is transported, in the transfer nip NT formed between the secondary transfer roller54and the transfer belt50.

Then, the recording medium P, onto which the toner image is transferred and which is transported by the delivery member48, is delivered to the belt unit60. Then, the recording medium P is transported by the belt unit60while being sandwiched between the circulating fixing belt74and the pressure roller102, such that the toner images formed on the recording medium P are heated, pressed, and fixed to the recording medium P.

When the toner images are fixed to one recording medium P by the fixing device34, the process proceeds to step S200.

In step S200, the counter62(seeFIG. 8) counts the number of recording media P to which toner images have been fixed by the fixing device34, for each size. That is, in step S200,1is added to the number of recording media P previously counted by the counter62. Then, the counter62stores the number of recording media P to which toner images have been continuously fixed by the fixing device34, for each size.

For example, when toner images have been continuously fixed to 300 A4-size recording media P by the fixing device34, and when the printing job ends, the controller28resets the number of recording media P counted by the counter62(back to zero). When the number of recording media P counted by the counter62is reset, the process proceeds to step S300. In addition, when the number of recording media P counted by the counter62does not reach the threshold of 300 or the printing job has not been ended, the process returns to step S100such that toner images are formed and fixed to the recording medium P. In addition, the printing job may be pending for the 30 continuous recording media P.

In step S300, the controller28switches the first mode of each unit to the second mode for restoring the fixing belt74having edge flaws caused by the continuous fixing of 300 recording media P. In the second mode, the controller28stops the operations of the toner image forming units30of the image forming unit12. Further, the controller28controls the transport unit14to send the embossed sheet S that is accommodated in the accommodating tray20a, to the transport path16. Then, as illustrated inFIG. 2, when the leading edge sensor84detects the leading edge of the embossed sheet S that is being transported, the controller28controls the delivery member48to stop the operation of the delivery member48, and controls the fixing device34to stop the operation of the fixing device34. In this state, the leading edge of the embossed sheet S is in contact with the guide110b.

Further, the controller28controls the movement units106to move the pressure roller102disposed at the contact position to the separation position (see the double chain line inFIG. 2). When the pressure roller102is moved to the separation position, the controller28controls the voltage application unit64(seeFIG. 8) to apply a voltage to the halogen heater inside the first heating roller78and the halogen heater inside the second heating roller80.

Further, as illustrated inFIG. 1, the controller28controls the second heating roller80to rotate the second heating roller80, such that the fixing belt74circulates at the same peripheral speed as that in the first mode. In this way, when the delivery member48is stopped from transporting the embossed sheet S and the fixing belt74is circulated, a friction occurs between the embossed sheet S and the peripheral surface of the fixing belt74. As a result of the friction, the state of the peripheral surface of the fixing belt74becomes uniform, so that the fixing belt74having the edge flaws is restored.

Then, when the fixing belt74circulates for a predetermined time (for example, for 30 seconds), the controller28controls the movement units106to move the pressure roller102disposed at the separation position to the contact position (see the double chain line inFIG. 1), so as to operate the pressure roller102. Further, the controller28operates the delivery member48to eject the embossed sheet S to the outside of the apparatus body10a, and then, stops the operation of each unit to end the second mode. When the second mode ends, the process proceeds to step S400.

In step S400, the controller28determines whether the image forming apparatus10receives an additional printing job, and when it is determined that the image forming apparatus10receives an additional printing job, the process returns to step S100such that the controller28switches the second mode of each unit to the first mode to start the process of the printing job.

Meanwhile, when it is determined that the image forming apparatus10does not receive an additional printing job, the controller28makes the image forming apparatus10be in the non-operating state, and ends the series of operations.

An evaluation is conducted for a case where the second mode is provided, using Versant 180P manufactured by Fuji Xerox Co., Ltd., as an image forming apparatus. The evaluation is described below.

In a state where the pressure roller is disposed at the contact position and the fixing belt is heated, 400 recording media P are caused to continuously pass through the fixing device. It is noted that no images are formed on the recording media P that pass through the fixing device. As for each recording medium P, A4-size New-DV (basis weight of 350 g/m2) manufactured by Hokuetsu Co., Ltd., is used.

After the 400 recording media P are continuously transported to the fixing device, a blue solid image (area coverage of 100%) is formed using an A3-size OS-coated paper (basis weight of 127 g/m2) manufactured by Fuji Xerox Co., Ltd. The image quality of the solid image is evaluated.

As described above, in “Evaluation Specification-01”, the second mode is not provided.

After Evaluation-01 is completed, an A3-size mermaid snow white (basis weight of 209 g/m2) manufactured by Tokushu Tokai Paper Co., Ltd., is used as the embossed sheet S for the second mode. Then, the pressure roller102is moved to the separation position, the leading edge of the embossed sheet S is brought into contact with the guide110b, the transport of the embossed sheet S is stopped, and in this state, the fixing belt74is caused to circulate for 30 seconds.

After the circulation of the fixing belt74, the pressure roller102is moved to the contact position, and a blue solid image (area coverage of 100%) is formed using the A3-size OS-coated paper (basis weight of 127 g/m2) manufactured by Fuji Xerox Co., Ltd. The image quality of the solid image is evaluated.

As described above, in “Evaluation Specification-02”, the second mode is provided, and the fixing belt74is caused to circulate for 30 seconds.

After Evaluation-02 is completed, the pressure roller102is moved to the separation position. Further, the leading edge of the A3-size mermaid snow white is brought into contact with the guide110b, the transport of the embossed sheet S is stopped, and in this state, the fixing belt74is caused to further circulate for 30 seconds. That is, in consideration of Evaluation Specification-02, the fixing belt74is caused to circulate for a total of 60 seconds.

After the circulation of the fixing belt74, the pressure roller102is moved to the contact position, and a blue solid image (area coverage of 100%) is formed using the A3-size OS-coated paper (basis weight of 127 g/m2) manufactured by Fuji Xerox Co., Ltd. The image quality of the solid image is evaluated.

As described above, in “Evaluation Specification-03”, the second mode is provided, and the fixing belt74is caused to circulate for a total of 60 seconds.

An evaluation is conducted on the image quality of the blue solid image formed on the OS-coated paper in each evaluation specification. The symbol “B” is given in a case where the deterioration of image quality caused by edge flaws of the fixing belt74is visually recognized, the symbol “A” is given in a case where the deterioration of image quality caused by edge flaws of the fixing belt74is visually recognized, but is allowable in terms of merchantability, and the symbol “AA” is given in a case where the deterioration of image quality caused by edge flaws of the fixing belt74is not visually recognized.

FIG. 9represents the evaluation results in a table. As represented in the table, the evaluation result of “Evaluation Specification-01” in which the second mode is not provided is “B”. In addition, the evaluation result of “Evaluation Specification-02” in which the second mode is provided and the fixing belt74is caused to circulate for 30 seconds is “A”. Further, the evaluation result of “Evaluation Specification-03” in which the second mode is provided and the fixing belt74is caused to circulate for a total of 60 seconds is “AA”.

SUMMARY

As seen from the evaluation results above, in the image forming apparatus10, the deterioration of image quality caused by edge flaws of the fixing belt74is prevented by providing the second mode. In other words, in the image forming apparatus10, the deterioration of image quality caused by edge flaws of the fixing belt74is prevented without securing a space where a refresh roller is disposed.

In addition, in the image forming apparatus10, the embossed sheet S having the maximum width passes through the fixing device34in the second mode. As a result, it is possible to prevent the deterioration of quality of an image formed on a recording medium P having a size other than the minimum size on which an image is formable, without securing a space where a refresh roller is disposed.

In addition, in the image forming apparatus10, the pressure roller102is disposed at the separation position in the second mode, such that the pressure applied to the embossed sheet S by the pressure roller102becomes weak. As a result, the difference between the transport speed of the embossed sheet S and the peripheral speed of the fixing belt74increases, as compared with a case where the pressure roller102is disposed at the contact position.

In addition, in the image forming apparatus10, the delivery member48is stopped from transporting the embossed sheet S in the second mode. As a result, the time during which the state of the peripheral surface of the fixing belt74is made uniform by the friction generated between the embossed sheet S and the peripheral surface of the fixing belt74is reduced, as compared with a case where the embossed sheet S is transported by the delivery member48. In other words, the time of the second mode is reduced, as compared with a case where the embossed sheet S is transported by the delivery member48.

In addition, in the image forming apparatus10, when the fixing device34continuously fixes toner images to 300 A4-size recording media P, and further, when the printing job ends, the first mode is switched to the second mode. The first mode is switched to the second mode when edge flaws are highly likely to occur in the fixing belt74, as compared with a case where the first mode is also switched to the second mode when, while toner images are being fixed to recording media P having a predetermined width, toner images are fixed to recording media P having a width other than the predetermined width. In other words, the number of times for switching the first mode to the second mode is reduced.

In addition, in the image forming apparatus10, the embossed sheet S is used as a sheet member in the second mode. As a result, the frictional force generated between the sheet member and the peripheral surface of the fixing belt74becomes strong, as compared with a case where a plain paper is used. In addition, the “plain paper” refers to paper that is used for an ordinary printing, and is, for example, the J paper (manufactured by Fuji Xerox Co., Ltd.).

In addition, since the frictional force generated between the sheet member and the peripheral surface of the fixing belt74becomes relatively strong, the time of the second mode is reduced, as compared with a case where the plain paper is used.

Second Exemplary Embodiment

An example of an image forming apparatus according to a second exemplary embodiment of the present disclosure will be described with reference toFIG. 12. In addition, the second exemplary Embodiment will be described focusing on differences from the first exemplary embodiment.

An image forming apparatus210according to the second exemplary embodiment includes an input unit220for switching the first mode to the second mode according to an input by a user, and a recommending unit230that recommends a user to switch the first mode to the second mode based on an inspection result of the image inspecting unit24(seeFIG. 11).

Specifically, as illustrated inFIG. 12, a user interface212of the image forming apparatus210displays the input unit220for switching the first mode to the second mode, and the recommending unit230that recommends a user to switch the first mode to the second mode.

In this configuration, when the controller28determines that the deterioration of image quality occurs due to edge flaws of the fixing belt74, based on the inspection of the image inspecting unit24, the recommending unit230that has been turned off is turned on. Then, when the user touches the input unit220, the first mode is switched to the second mode. When the first mode is switched to the second mode by the user's touch of the input unit220, the recommending unit230that has been turned on is turned off, and further, the number of sheets counted by the counter62(seeFIG. 8) is reset.

As described above, in the image forming apparatus210, the input unit220is provided, such that the first mode is switched to the second mode according to the user's intention.

In addition, in the image forming apparatus210, since the recommending unit230is provided that recommends to switch the first mode to the second mode, the first mode is switched to the second mode by the user at an appropriate timing, as compared with a case where the recommending unit is not provided. The other operations of the second exemplary embodiment are the same as those of the first exemplary embodiment.

In addition, while the exemplary embodiments of the present disclosure have been described in detail, the present disclosure is not limited to the exemplary embodiments. It is obvious to one of ordinary skill in the art that other various exemplary embodiments may be taken in the scope of the present disclosure. For example, while the fixing belt74functions as the heating unit in the exemplary embodiments described above, the heating unit may be a roller-shaped heating roller.

In addition, in the exemplary embodiments described above, the sheet member with the maximum width is used in the second mode. However, the width of the sheet member used in the second mode has only to be wider than the minimum width of the recording medium P usable in the image forming apparatus10or210. That is, the width of the sheet member has only to be wider than the width of the recording medium having the minimum size on which an image is formable.

In addition, in the exemplary embodiments described above, the pressing force of the pressure roller102is made weak in the second mode, as compared with the first mode, by providing the pressure roller102at the separation position. However, the pressing force of the pressure roller may be made weak in a state of maintaining the contact between the pressure roller and the fixing belt. As a result, the contact between the sheet member and the fixing belt is maintained in the second mode. In this case, the pressure roller is used as the contact maintaining unit.

In addition, in the exemplary embodiments described above, the friction between the sheet member and the peripheral surface of the fixing belt is generated in the second mode, by stopping the delivery member48from transporting the sheet member. Alternatively, the friction between the sheet member and the peripheral surface of the fixing belt may be generated by making the transport speed at which the delivery member transports the sheet member slower than the peripheral speed of the fixing belt. In this case, the operation achieved by stopping the delivery member from transporting the sheet member is not achieved in the second mode.

In addition, in the exemplary embodiments described above, the delivery member48is stopped from transporting the sheet member only once in the second mode. However, after the delivery member is stopped from transporting the sheet member, the delivery member may transport the sheet member, and the delivery member may be stopped from transporting the sheet member again in a state of maintaining the contact between the sheet member and the fixing belt. As a result, the friction with the fixing belt occurs at two portions of the sheet member, so that the deterioration of image quality caused by edge flaws of the fixing belt74is further prevented, as compared with the friction occurs at one portion of the sheet member.

In addition, in the exemplary embodiments described above, when the fixing device34continuously fixes toner images to 300 A4-size recording media P in the first mode, and when the printing job ends, the first mode is switched to the second mode. However, when the fixing device34continuously fixes toner images to the 300 A4-size recording media P, the first mode may be switched to the second mode even during the printing job.

In addition, in the exemplary embodiments described above, when the fixing device34continuously fixes toner images to 300 A4-size recording media P in the first mode, and when the printing job ends, the first mode is switched to the second mode. However, toner images may not be continuously fixed to the 300 recording media, and toner images may be fixed to recording media having a different width from that of the 300 recording media in the middle of fixing toner images to the 300 recording media. Accordingly, the operation achieved by switching the first mode to the second mode after toner images are continuously fixed to the 300 recording media P is not achieved. However, the first mode is switched to the second mode when edge flaws are highly likely to occur in the fixing belt74, as compared with a case where the first mode is switched to the second mode based on only the number of recording media P to which toner images have been fixed. In other words, the number of times for switching the first mode to the second mode is reduced.

In addition, in the exemplary embodiments described above, the peripheral speed of the fixing belt74in the first mode is maintained in the second mode. However, the peripheral speed of the fixing belt74in the second mode may be made faster than the peripheral speed of the fixing belt74in the first mode. In this case, the time of the second mode is set to be shorter than that in a case where the peripheral speed of the fixing belt74in the first mode is maintained in the second mode.

In addition, in the exemplary embodiments described above, the embossed sheet S having concave-convex patterns is used in the second mode. However, a plain paper may be used in the second mode. In order to achieve the operation achieved by using the embossed sheet S when the plain paper is used, the time during which the fixing belt74circulates needs to be made longer than that when the embossed sheet S is used.

In addition, although not specifically described in the exemplary embodiments above, the sheet member used in the second mode may be supplied from the manual feed tray38.

In addition, in the exemplary embodiments described above, when the fixing device34fixes toner images to 300 A4-size recording media P. and when the printing job ends, the first mode is switched to the second mode. However, the fixing device34may continuously fix toner images to a predetermined number of recording media P having a predetermined width. In this case, recording media having a width other than the A4 size may be used, and the number of recording media may not be 300.

In addition, although not specifically described in the exemplary embodiments above, edge flaws easily occur in the fixing belt74when a relatively thick paper is used as the recording medium, as compared with a case where a relatively thin paper is used. Thus, the number of recording media which is necessary for switching the first mode to the second mode may be changed according to the basis weight of a recording medium to be used.

In addition, although not specifically described in the exemplary embodiments above, a sheet member on which an image is not formable and which is dedicated for the second mode may be used as the embossed sheet S.

In addition, although not specifically described in the second exemplary embodiment, the recommending unit230that has been turned off may be turned on, for example, when the fixing device34continuously fixes toner images to 250 recording media P having the same size and the printing job ends.