JP2017106948A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of suppressing the deformation or breakage of the end of a fixing belt, while suppressing the occurrence of an edge scratch in the fixing belt and to provide an image forming apparatus including the fixing device.SOLUTION: The fixing device includes a roller moving part F6 which moves one of a first roller (fixing roller F2) and a second roller (heating roller F3) in a horizontal direction, a fixing belt F4 which is moved in parallel in conjunction with the movement of one of the first roller and the second roller, an area setting part (control part 100) which sets the movable area of the fixing belt F4 on the basis of the position of the end in the width direction of the fixing belt F4 detected by a sensor F5 and a condition related to durability, a movement amount setting part (control part 100) which sets the movement amount of the fixing belt F4 on the basis of the movable area, and a roller control part (control part 100) which controls the movement amount of one of the first roller and the second roller on the basis of the movement amount of the fixing belt F4.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device.

  Conventionally, an electrostatic latent image formed on a photosensitive drum is developed with toner to form a toner image, the formed toner image is transferred to a sheet, and the transferred toner image is heated and fixed by a fixing device. Thus, an image forming apparatus that forms an image on a sheet is known.

  In the image forming apparatus described above, when sheets of the same size are continuously passed through the fixing device, the edge portion of the sheet passes through the same portion in the width direction of the fixing member (fixing belt). A load is continuously applied to the top, causing wear. Therefore, there is a problem that when a larger size paper is passed, image defects such as gloss streaks occur due to the influence of the worn portion.

  Therefore, in order to reduce the wear of the fixing belt due to the edge portion of the paper, the fixing belt is moved in conjunction with the heating roller by moving the heating roller that stretches the fixing belt in a direction orthogonal to the conveyance direction of the paper, A technique for dispersing a contact portion with an edge portion of a sheet is disclosed (for example, see Patent Document 1).

JP 2012-47848 A

However, in the configuration described in Patent Document 1, when the two rollers for stretching the fixing belt are not parallel due to component tolerances or the like, if the fixing belt is moved, the meandering of the fixing belt cannot be controlled. There is a problem in that edge flaws occur on the fixing belt.
Further, when the fixing belt is largely moved, the fixing belt may come into contact with a regulating member that regulates the separation from the roller, and the end of the fixing belt may be deformed or broken.

  An object of the present invention is to provide a fixing device capable of suppressing deformation and breakage of an end portion of a fixing belt while suppressing occurrence of edge scratches on the fixing belt, and an image forming apparatus including the fixing device. To do.

The invention described in claim 1 has been made to achieve the above object,
In a fixing device for fixing a toner image transferred on a sheet to the sheet,
A transport roller disposed on the lower surface side of the paper;
A first roller disposed on the upper surface side of the paper so as to face the transport roller;
A second roller disposed above the first roller;
A roller moving unit that moves one of the first roller and the second roller in a horizontal direction around one end in the axial direction;
Fixing that is stretched by the first roller and the second roller to form a fixing surface of the paper and that moves in parallel in the width direction in conjunction with the movement of either the first roller or the second roller. Belt,
A heating unit for heating the fixing belt;
A sensor for detecting the position of the end in the width direction of the fixing belt;
An area setting unit for setting a movable area of the fixing belt based on the position of the end portion in the width direction of the fixing belt detected by the sensor and a condition relating to durability of the fixing belt;
A moving amount setting unit for setting a moving amount of the fixing belt based on a movable region of the fixing belt set by the region setting unit;
A roller control unit that controls a movement amount of one of the first roller and the second roller by the roller moving unit based on the movement amount of the fixing belt set by the movement amount setting unit;
It is characterized by providing.

According to a second aspect of the present invention, in the fixing device according to the first aspect,
The conditions relating to the durability of the fixing belt include the temperature of the fixing belt,
The area setting unit is configured to set such that the movable area of the fixing belt becomes narrower as the temperature of the fixing belt becomes higher.

According to a third aspect of the present invention, in the fixing device according to the first or second aspect,
The conditions relating to the durability of the fixing belt include a travel distance of the fixing belt,
The area setting unit sets the movable area of the fixing belt to be narrowed as the travel distance of the fixing belt becomes longer.

According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects,
The conditions relating to the durability of the fixing belt include a nip pressure in a nip portion formed by the transport roller and the first roller,
The region setting unit is configured to set the movable region of the fixing belt to be narrowed as the nip pressure in the nip portion increases.

The invention described in claim 5
In the image forming apparatus,
An image forming unit for forming a toner image on paper;
The fixing device according to any one of claims 1 to 4, wherein the toner image formed by the image forming unit is fixed to the paper.
It is characterized by providing.

  According to the present invention, it is possible to suppress the deformation and breakage of the end portion of the fixing belt while suppressing the occurrence of edge scratches on the fixing belt.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. FIG. 3 is a functional block diagram illustrating a control structure of the image forming apparatus according to the present embodiment. FIG. 2 is a perspective view illustrating a schematic configuration of a fixing device. It is a figure which shows an example of a mode that a heating roller and a fixing belt move. FIG. 4 is a diagram illustrating an example of a state in which a fixing belt moves to a movement target position. 5 is a flowchart showing an operation of the image forming apparatus according to the present embodiment. FIG. 4 is a diagram illustrating an example of a state in which a movement amount of a fixing belt with respect to a movement of a heating roller is measured. FIG. 6 is a diagram for explaining a movable region of the fixing belt.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  An image forming apparatus 10 according to the present embodiment is an intermediate transfer type color image forming apparatus using an electrophotographic process technology. As illustrated in FIGS. 1 and 2, an automatic document conveyance unit 20, a scanner unit 30, an image, and the like. The apparatus includes a forming unit 40, a paper feeding unit 50, a storage unit 60, an operation display unit 70, a control unit 100, and the like.

The automatic document transport unit 20 includes a placement tray on which the document D is placed, a mechanism for transporting the document D, a transport roller, and the like, and transports the document D to a predetermined transport path.
The scanner unit 30 includes an optical system such as a light source and a reflecting mirror. The scanner unit 30 irradiates the document D conveyed on a predetermined conveyance path or the document D placed on the platen glass, and receives reflected light. . The scanner unit 30 converts the received reflected light into an electrical signal and outputs the electrical signal to the control unit 100.

The image forming unit 40 includes a yellow image forming unit Y, a magenta image forming unit M, a cyan image forming unit C, a black image forming unit K, an intermediate transfer belt T, a fixing device F, and the like.
Each image forming unit YMCK forms yellow, magenta, cyan, and black toner images on the photosensitive drum 41, and primarily transfers the YMCK toner images formed on the photosensitive drum 41 to the intermediate transfer belt T.
Since the configuration and operation of each image forming unit YMCK are the same, a series of image forming operations performed by the image forming unit 40 will be described below taking the yellow image forming unit Y as an example.

The photoreceptor drum 41 is composed of a photoreceptor layer having a surface composed of an organic semiconductor layer in which a phthalocyanine pigment is dispersed in polycarbonate and a charge transport layer.
The charging device 42 uniformly charges the photosensitive drum 41.
The exposure device 43 exposes the non-image area of the photoconductive drum 41 based on the image data Dy from the control unit 100 to remove the exposed portion of the charge, and forms an electrostatic latent image on the image area of the photoconductive drum 41. Form.
The developing device 44 supplies toner that is a developer onto the electrostatic latent image formed on the photosensitive drum 41, and forms a yellow toner image on the photosensitive drum 41.

The primary transfer roller 45 primarily transfers the yellow toner image formed on the photosensitive drum 41 to the intermediate transfer belt T.
Similarly, the other image forming units MCK also primarily transfer magenta, cyan, and black toner images onto the intermediate transfer belt T. As a result, a color toner image of each color of YMCK is formed on the intermediate transfer belt T.

The intermediate transfer belt T is a semiconductive endless belt that is suspended and supported rotatably by a plurality of rollers, and is driven to rotate as the rollers rotate.
The intermediate transfer belt T is pressed against the respective photosensitive drums 41 facing each other by the primary transfer roller 45. A transfer current corresponding to the applied voltage flows through each of the primary transfer rollers 45. As a result, each toner image developed on the surface of each photoconductor drum 41 is primarily transferred onto the intermediate transfer belt T sequentially by each primary transfer roller 45.

  The secondary transfer roller 46 is pressed against the intermediate transfer belt T and rotates accordingly, thereby transferring YMCK color toner images formed on the intermediate transfer belt T to the paper feed trays 51 to 53 of the paper feed unit 50. Secondary transfer is performed on the paper P conveyed from the first. The secondary transfer roller 46 is disposed in contact with the secondary transfer counter roller 461 via the intermediate transfer belt T, and a transfer nip formed between the secondary transfer roller 46 and the secondary transfer counter roller 461 is formed on the sheet. By passing P, the toner image on the intermediate transfer belt T is secondarily transferred to the paper P.

  As shown in FIGS. 1 to 3, the fixing device F includes a heating conveyance roller (conveyance roller) F <b> 1 disposed on the lower surface side of the paper P, a fixing roller (first roller) F <b> 2 disposed on the upper surface side, and fixing. A heating roller (second roller) F3 disposed above the roller F2, a fixing belt F4, a sensor F5 for detecting the end position F41 in the width direction of the fixing belt F4, and a roller for moving the heating roller F3 in the horizontal direction. And a moving part F6 (see FIG. 2). The fixing device F heats and presses the sheet P by passing the sheet P through a nip formed by heating and pressing the heating and conveying roller F1 and the fixing roller F2, and the transferred toner image is transferred to the sheet. In addition to fixing to P, the paper P is transported downstream in the transport direction.

The heating / conveying roller F1 is formed in a cylindrical shape from rubber, and has a high-output heater inside, similar to the heating roller F3. The heating conveyance roller F1 rotates in the forward direction with respect to the conveyance direction of the paper P, and heats and pressurizes the non-fixing surface of the conveyed paper P. The heating / conveying roller F1 is configured to be capable of pressure bonding or separation with respect to the fixing roller F2, and is configured to be able to control the nip pressure at the nip portion.
The fixing roller F2 is formed in a cylindrical shape with sponge-like foam rubber having a lower hardness than the heating and conveying roller F1, rotates in the forward direction with respect to the conveying direction of the paper P, and the fixing surface of the conveyed paper P Is heated and pressurized through the fixing belt F4.
The heating roller F3 includes a high-power heater inside, rotates in the forward direction with respect to the conveyance direction of the paper P, and heats the fixing roller F2 via the fixing belt F4. That is, the heating roller F3 functions as the heating unit of the present invention.
The fixing belt F4 is formed wider than the paper width, and is stretched by the fixing roller F2 and the heating roller F3 to form a fixing surface of the paper P, and heats the paper P.

Further, as shown in FIGS. 4A to 4C, the heating roller F3 is configured to be movable (rotated) in the horizontal direction around the one end F31 in the axial direction. The heating roller F3 moves in the horizontal direction under the control of the roller moving unit F6 by the control unit 100.
The fixing belt F4 is configured to move in parallel in the width direction (the axial direction of the heating roller F3 and the fixing roller F2) in conjunction with the movement of the heating roller F3 in the horizontal direction. Specifically, as shown in FIG. 4B, the fixing belt F4 is moved in front of the width direction (in the drawing) in conjunction with the movement of the heating roller F3 to the upstream side in the paper conveyance direction (arrow G1 in the drawing). Move to arrow G2). Further, as shown in FIG. 4C, the fixing belt F4 is linked to the movement of the heating roller F3 to the downstream side in the paper conveyance direction (arrow G3 in the figure), and the back side in the width direction (arrow G4 in the figure). Move to.
Note that the fixing belt F4 is heated even when it is translated in the width direction by the regulating members F7 (see FIG. 5, FIG. 7, FIG. 8, etc.) provided at the positions of both ends in the axial direction of the heating roller F3. It is regulated so as not to come off from the roller F3.

The control unit 100 controls the roller moving unit F6 to move the heating roller F3 in the horizontal direction, thereby translating the fixing belt F4 in the width direction. As shown in FIGS. 5A and 5B, the control unit 100 detects an end position F41 on the front side in the width direction of the fixing belt F4 detected by the sensor F5 and a movement target position F42 of the fixing belt F4. And the amount of movement of the heating roller F3 in the horizontal direction is controlled. The movement target position F42 is set between the end position F41 detected by the sensor F5 and the regulating member F7. The control unit 100 controls the amount of movement of the heating roller F3 in the horizontal direction based on the distance from the end position F41 to the movement target position F42.
In FIG. 5, the heating roller F <b> 3 is omitted for convenience of explanation.

As described above, the image forming unit 40 heats and pressurizes the sheet onto which the YMCK color toner images are secondarily transferred by the fixing device F, and then discharges the sheet to the outside through a predetermined conveyance path.
The above is a series of image forming operations by the image forming unit 40.

The cleaning device 47 removes residues such as residual toner and paper dust remaining on the surface of the photosensitive drum 41 after the primary transfer. Further, the cleaning device 48 removes residues remaining on the intermediate transfer belt T after the secondary transfer.
The cleaning device 47 and the cleaning device 48 are the same in that they remove the residue remaining on the photosensitive drum 41 or the intermediate transfer belt T, and perform the same configuration and operation.

  The paper feed unit 50 includes a plurality of paper feed trays 51 to 53, and stores a plurality of different types of paper P in the paper feed trays 51 to 53. The paper feeding unit 50 feeds the paper P accommodated by a predetermined conveyance path to the image forming unit 40.

  The storage unit 60 includes, for example, an HDD (Hard Disk Drive), a semiconductor memory, and the like, and stores data such as program data and various setting data so that the control unit 100 can read and write the data. The storage unit 60 also includes a table that defines the relationship between the temperature of the fixing belt F4 (fixing temperature) and the movable area W1 of the fixing belt F4, and the travel distance of the fixing belt F4 and the movable area W1 of the fixing belt F4. A table that defines the relationship is stored.

The operation display unit 70 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as the display unit 71 and the operation unit 72.
The display unit 71 displays various operation screens, operation states of functions, and the like according to a display control signal input from the control unit 100. In addition, it receives a touch operation by the user and outputs an operation signal to the control unit 100.
The operation unit 72 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100. The user can operate the operation display unit 70 to perform settings relating to image formation such as image quality setting, magnification setting, application setting, output setting, and paper setting, a paper conveyance instruction, and a device stop operation.

  The control unit 100 is configured to include a CPU, a RAM, a ROM, and the like. The CPU expands various programs stored in the ROM to the RAM, and cooperates with the expanded various programs, so that the automatic document feeder 20, The operation of each unit of the image forming apparatus 10 such as the scanner unit 30, the image forming unit 40, the paper feeding unit 50, the storage unit 60, and the operation display unit 70 is comprehensively controlled (see FIG. 2). For example, the control unit 100 performs various image processing by inputting an electrical signal from the scanner unit 30, and outputs image data Dy, Dm, Dc, Dk of each color of YMCK generated by the image processing to the image forming unit 40. . The control unit 100 controls the operation of the image forming unit 40 to form an image on the paper P.

Next, the operation of the image forming apparatus 10 according to the present embodiment will be described with reference to the flowchart of FIG.
First, the control unit 100 measures the movement amount A1 of the fixing belt F4 when the heating roller F3 is moved by a predetermined amount (ΔB) (step S101). Specifically, as shown in FIG. 7, the control unit 100 controls the roller moving unit F6 to move the heating roller F3 by a predetermined amount (ΔB), and the fixing belt F4 continuously detected by the sensor F5. By acquiring the end position F41, the movement amount A1 of the fixing belt F4 with respect to the movement of the heating roller F3 is measured. This makes it possible to accurately calculate the amount of movement of the heating roller F3 when it is desired to move the fixing belt F4 by a predetermined amount.

Next, the control unit 100 sets the movable region W1 of the fixing belt F4 based on the temperature (fixing temperature) of the fixing belt F4 and the travel distance of the fixing belt F4 (step S102). That is, the control unit 100 functions as an area setting unit of the present invention. Specifically, the control unit 100 refers to a table that defines the relationship between the fixing temperature and the movable region W1, and a table that defines the relationship between the travel distance of the fixing belt F4 and the movable region W1. A movable area W1 is set. The fixing temperature is set in advance for each paper type of the paper through which the fixing device F is passed. For example, since the strength of the fixing belt F4 decreases as the fixing temperature increases, the control unit 100 sets the movable region W1 to be narrow to avoid contact with the regulating member F7. Further, since the strength of the fixing belt F4 decreases as the travel distance becomes longer, the control unit 100 sets the movable region W1 to be narrow so as to avoid contact with the regulating member F7.
Here, as shown in FIG. 8, the movable region W1 of the fixing belt F4 is set under a condition that satisfies W1 <W2, where the length between the pair of regulating members F7 is W2. In FIG. 8, the description of the heating roller F3 is omitted for convenience of explanation.

  Next, the control unit 100 sets the movement amount A of the fixing belt F4 based on the movable area W1 set in step S102 (step S103). That is, the control unit 100 functions as a movement amount setting unit of the present invention. Specifically, as shown in FIG. 8, when the length in the width direction of the fixing belt F4 is W, the control unit 100 sets the movement amount A of the fixing belt F4 under a condition that satisfies A + W ≦ W1. To do. In step S103, the movement amount A of the fixing belt F4 is set, so that the movement target position F42 (see FIG. 5) of the fixing belt F4 is set.

Next, the control unit 100 refers to the movement amount A of the fixing belt F4 set in step S103 and the measurement result in step S101, and calculates the movement amount of the heating roller F3 (step S104). Next, the control unit 100 controls the roller moving unit F6 to move the heating roller F3 according to the moving amount calculated in step S104 (step S105).
That is, the control unit 100 functions as a roller control unit of the present invention.

As described above, the fixing device F of the image forming apparatus 10 according to the present embodiment has the conveyance roller (heating conveyance roller F1) disposed on the lower surface side of the sheet and the upper surface side of the sheet so as to face the conveyance roller. The first roller (fixing roller F2) disposed on the second roller, the second roller (heating roller F3) disposed above the first roller, and the second roller are moved in the horizontal direction around one axial end. A roller moving portion F6 to be stretched, a fixing belt F4 that is stretched by the first roller and the second roller to form a fixing surface of the paper, and moves in parallel in the width direction in conjunction with the movement of the second roller, and fixing A heating unit (heating roller F3) for heating the belt F4, a sensor F5 for detecting the position of the end in the width direction of the fixing belt F4, and the fixing belt F4 detected by the sensor F5 Based on the position of the end in the width direction and the conditions relating to the durability of the fixing belt F4, an area setting unit (control unit 100) that sets a movable area of the fixing belt F4, and the fixing belt F4 set by the area setting unit. A moving amount setting unit (control unit 100) for setting the moving amount of the fixing belt F4 based on the movable region of the roller, and a roller moving unit F6 based on the moving amount of the fixing belt F4 set by the moving amount setting unit. A roller control unit (control unit 100) for controlling the amount of movement of the second roller.
Therefore, according to the fixing device F according to the present embodiment, since the fixing belt F4 can be appropriately moved in the width direction, the occurrence of edge scratches on the fixing belt F4 can be suppressed. Further, since the movable region of the fixing belt F4 can be adjusted in consideration of the durability of the fixing belt F4, deformation and breakage of the end portion of the fixing belt F4 can be suppressed.

Further, according to the fixing device F according to the present embodiment, the condition relating to the durability of the fixing belt F4 includes the temperature of the fixing belt F4, and the region setting unit sets the fixing belt F4 as the temperature of the fixing belt F4 increases. The movable area is set to be narrow.
Therefore, according to the fixing device F according to the present embodiment, after determining the durability of the fixing belt F4 based on the fixing temperature set for each paper type of the paper to be passed, the movable region of the fixing belt F4 is determined. Therefore, it is possible to set a more appropriate movable region in consideration of suppression of edge flaws in the fixing belt F4 and suppression of deformation and breakage of the end portion of the fixing belt F4.

Further, according to the image forming apparatus 10 according to the present embodiment, the condition relating to the durability of the fixing belt F4 includes the travel distance of the fixing belt F4, and the area setting unit increases the travel distance of the fixing belt F4 as the travel distance of the fixing belt F4 increases. The movable area of the fixing belt F4 is set to be narrow.
Therefore, the image forming apparatus 10 according to the present embodiment adjusts the movable region of the fixing belt F4 after judging the durability of the fixing belt F4 based on the travel distance of the fixing belt F4 when the paper is passed. Therefore, it is possible to set a more appropriate movable region in consideration of suppression of edge flaws in the fixing belt F4 and suppression of deformation and breakage of the end portion of the fixing belt F4.

  As mentioned above, although concretely demonstrated based on embodiment which concerns on this invention, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.

For example, in the above embodiment, the heating roller F3 is moved in the horizontal direction, but the present invention is not limited to this. For example, instead of the heating roller F3, the fixing roller F2 may be moved in the horizontal direction. However, moving the heating roller F3 in the horizontal direction is more preferable in terms of fixing efficiency than moving the fixing roller F2 in the horizontal direction.
Moreover, in the said embodiment, although the heating roller F3 was illustrated and demonstrated as a heating part, it is not limited to this. For example, instead of the heating roller F3, the fixing roller F2 may be provided with a heating function so that the fixing roller F2 is used as a heating unit. Further, another configuration capable of heating the fixing belt F4 may be used as the heating unit.

  In the above-described embodiment, when the movable region W1 of the fixing belt F4 is set, the setting is made based on the travel distance of the fixing belt F4. However, the present invention is not limited to this. For example, the movable region W1 of the fixing belt F4 may be set based on the durable number of the fixing belt F4 instead of the travel distance of the fixing belt F4. In this case, since the strength of the fixing belt F4 decreases as the number of durable sheets increases, the control unit 100 sets the movable region W1 narrow so as to avoid contact with the regulating member F7.

  In the above embodiment, the movable region W1 of the fixing belt F4 is set based on the fixing temperature and the travel distance of the fixing belt F4. However, the present invention is not limited to this. For example, the movable area W1 may be set based only on the fixing temperature, or the movable area W1 may be set based only on the travel distance of the fixing belt F4.

  The conditions for setting the movable region W1 of the fixing belt F4 are not limited to the fixing temperature and the travel distance of the fixing belt F4, and any conditions may be used as long as the conditions are related to the durability of the fixing belt F4. . For example, the movable region W1 may be set based on the nip pressure at the nip portion instead of the fixing temperature and the travel distance of the fixing belt F4. In this case, the control unit 100 sets the movable region W1 by referring to a table that defines the relationship between the nip pressure and the movable region W1. The nip pressure is set in advance for each paper type of the paper through which the fixing device F is passed. For example, as the nip pressure increases, the control unit 100 increases the impact when the fixing belt F4 and the regulating member F7 come into contact with each other. To do.

As described above, by setting the movable region W1 based on the nip pressure in the nip portion, the durability level of the fixing belt F4 is determined based on the nip pressure set for each paper type of the paper to be passed. In addition, since the movable region of the fixing belt F4 can be adjusted, a more appropriate movable region is set in consideration of suppression of edge flaws in the fixing belt F4 and suppression of deformation and breakage of the fixing belt F4 end. be able to.
Of course, it is possible to set the movable region W1 based on the fixing temperature and the travel distance of the fixing belt F4 in addition to the nip pressure in the nip portion.

  Further, when the movement amount A of the fixing belt F4 is set, it may be set under any condition as long as A + W ≦ W1 is satisfied. However, the movement amount A to be set is constantly changed, that is, the fixing belt F4 is always turned on. It is more preferable to move in the width direction. As described above, by constantly moving the fixing belt F4 in the width direction, the contact portion of the fixing belt F4 with the paper can be dispersed at all times, so that wear of the fixing belt F4 can be further reduced.

  In addition, the detailed configuration of each apparatus constituting the fixing device and the image forming apparatus and the detailed operation of each apparatus can be appropriately changed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 20 Automatic document conveyance part 30 Scanner part 40 Image forming part 41 Photosensitive drum 42 Charging apparatus 43 Exposure apparatus 44 Developing apparatus 45 Primary transfer roller 46 Secondary transfer rollers 47 and 48 Cleaning apparatus T Intermediate transfer belt F Fixing apparatus F1 Heating conveyance roller (conveyance roller)
F2 fixing roller (first roller)
F3 heating roller (second roller, heating section)
F4 fixing belt F5 sensor F6 roller moving unit F7 regulating member 50 paper feeding unit 60 storage unit 70 operation display unit 100 control unit (area setting unit, movement amount setting unit, roller control unit)

Claims (5)

In a fixing device for fixing a toner image transferred on a sheet to the sheet,
A transport roller disposed on the lower surface side of the paper;
A first roller disposed on the upper surface side of the paper so as to face the transport roller;
A second roller disposed above the first roller;
A roller moving unit that moves one of the first roller and the second roller in a horizontal direction around one end in the axial direction;
Fixing that is stretched by the first roller and the second roller to form a fixing surface of the paper and that moves in parallel in the width direction in conjunction with the movement of either the first roller or the second roller. Belt,
A heating unit for heating the fixing belt;
A sensor for detecting the position of the end in the width direction of the fixing belt;
An area setting unit for setting a movable area of the fixing belt based on the position of the end portion in the width direction of the fixing belt detected by the sensor and a condition relating to durability of the fixing belt;
A moving amount setting unit for setting a moving amount of the fixing belt based on a movable region of the fixing belt set by the region setting unit;
A roller control unit that controls a movement amount of one of the first roller and the second roller by the roller moving unit based on the movement amount of the fixing belt set by the movement amount setting unit;
A fixing device comprising: The conditions relating to the durability of the fixing belt include the temperature of the fixing belt,
The fixing device according to claim 1, wherein the area setting unit sets the movable area of the fixing belt to be narrowed as the temperature of the fixing belt increases. The conditions relating to the durability of the fixing belt include a travel distance of the fixing belt,
The fixing device according to claim 1, wherein the area setting unit sets the movable area of the fixing belt to be narrowed as the travel distance of the fixing belt becomes longer. The conditions relating to the durability of the fixing belt include a nip pressure in a nip portion formed by the transport roller and the first roller,
The fixing device according to claim 1, wherein the region setting unit sets the movable region of the fixing belt to be narrowed as a nip pressure in the nip portion increases. . An image forming unit for forming a toner image on paper;
The fixing device according to any one of claims 1 to 4, wherein the toner image formed by the image forming unit is fixed to the paper.
An image forming apparatus comprising:

Images