JP5846035B2 - Surface treatment apparatus, image forming apparatus, and image forming method - Google Patents

Description

  The present invention relates to a surface treatment apparatus, an image forming apparatus, and an image forming method.

  Conventionally, a toner image is formed on an image carrier such as a photosensitive drum using an electrophotographic process such as charging, exposure, and development, and after the toner image is formed on a sheet, the toner image is fixed on the sheet by a fixing device. An image forming apparatus is known.

In such an image forming apparatus, there is one in which an image forming portion is selectively heated by a thermal head (for example, Patent Document 1).
In addition, it is also known that a sheet fixed by a fixing device that performs fixing by heating and pressing with a heating member and a pressure member is further heated with a thermal head to give gloss.

JP 2005-181946 A

  By the way, when the sheet is passed through the fixing device, the temperature of the heating member is deprived by the passage of the sheet and partially decreases. Then, after passing a paper with a small width after passing a paper with a small width to the fixing device, a portion deprived of heat by the passage of a paper with a small width, and A temperature difference of the heating member occurs between other portions. Due to this temperature difference, there is a problem in that a level difference occurs in the gloss, and unevenness in gloss such as streaks occurs in the image formed on the paper and the image quality is degraded. Even if the thermal head described in Patent Document 1 is applied, the above-described problems are not taken into consideration, and thus the image quality cannot be improved.

  An object of the present invention is to provide a surface treatment apparatus, an image forming apparatus, and an image forming method capable of reducing uneven glossiness that occurs when the width of a sheet to be passed is changed.

In order to solve the above problems, the invention according to claim 1 is a surface treatment apparatus,
The sheet on which the toner image is formed is heated and pressed by a heating member and a pressure member, so that a region to be heated with respect to the sheet that has passed through a fixing device that fixes the toner image on the sheet is selectively heated. A surface treatment unit for performing surface treatment;
The width of the sheet on which the toner image is formed is detected, and based on the detection result, the fixing by the fixing device is changed from the first width sheet to the second width sheet larger than the first width. A control unit that controls the surface treatment unit to heat a region of the second width paper corresponding to a position where the first width paper passes through the fixing device when it is determined that
It is provided with.

The invention according to claim 2 is the surface treatment apparatus according to claim 1,
When the surface treatment is performed by the surface treatment unit on the plurality of sheets having the second width, the control unit reduces the heating temperature of the surface treatment unit every time the surface treatment is performed on the paper. And

According to a third aspect of the present invention, in the image forming apparatus,
An image forming unit for forming a toner image on paper;
A fixing unit that fixes the toner image on the sheet by heating and pressing the sheet on which the toner image is formed by the image forming unit with a heating member and a pressing member;
A surface treatment unit for selectively heating a region to be heated with respect to the paper fixed by the fixing unit and performing surface treatment of the paper;
A width of a sheet on which a toner image is formed by the image forming unit is detected, and based on the detection result, a second width in which fixing by the fixing unit is larger than the first width from the first width sheet Control to cause the surface treatment section to heat the area of the second width sheet corresponding to the position where the first width sheet passes through the fixing unit when it is determined that the sheet has been changed to the first sheet. A control unit to perform,
It is provided with.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect,
When the surface treatment is performed by the surface treatment unit on the plurality of sheets having the second width, the control unit reduces the heating temperature of the surface treatment unit every time the surface treatment is performed on the paper. And

The invention according to claim 5 is an image forming method,
An image forming step of forming a toner image on paper;
A fixing step of fixing the toner image on the paper by heating and pressurizing the paper on which the toner image is formed in the image forming step with a heating member and a pressure member of a fixing device;
A surface treatment step of performing surface treatment of the paper by selectively heating an area to be heated to the paper fixed in the fixing step;
Including
In the surface treatment step, when the fixing by the fixing device is changed from a first width sheet to a second width sheet larger than the first width, the first width sheet is fixed. A region of the second width paper corresponding to a position passing through the apparatus is heated.

The invention according to claim 6 is the image forming method according to claim 5,
In the surface treatment step, when the surface treatment is performed on the plurality of sheets having the second width by the surface treatment unit, the heating temperature is lowered every time the surface treatment is performed on the sheets.

  According to the present invention, it is possible to reduce uneven glossiness that occurs when the width of a sheet to be passed is changed.

1 is a diagram illustrating an internal configuration of an image forming apparatus. It is a top view which shows schematic structure of a surface treatment part. It is a figure explaining the relationship between the electric current amount and the calorie | heat amount administered to a paper. 2 is a block diagram illustrating a functional configuration of the image forming apparatus. FIG. It is a figure explaining generation | occurrence | production of gloss unevenness. It is a figure explaining the temperature distribution of a fixing roller. FIG. 6 is a diagram for explaining a change in temperature of a fixing roller. It is a flowchart explaining a heat processing. It is a figure explaining the transition of the glossiness in a paper. It is a figure explaining the heat_generation | fever temperature in the heat generating body of a surface treatment part. It is a figure explaining the change of the glossiness for every paper.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The scope of the invention is not limited to the illustrated example.

  For example, as shown in FIG. 1, the image forming apparatus 1 includes an image reading unit 30, an image forming unit 40, a paper feeding unit 50, and a surface processing unit 60.

  The image reading unit 30 includes an automatic document feeder (ADF), a platen glass, a CCD (Charge Coupled Device), and a light source. Then, the image reading unit 30 forms an image of the reflected light of the illumination scanned on the document supplied from the light source by the ADF or the document set at a predetermined position by the CCD and photoelectrically converts the reflected light. The image is read as R, G, and B signals, and the read analog image signal is converted into R, G, and B image data and output.

  The output image data undergoes predetermined image processing, is converted into YMCK data, and is sent to the image forming unit 40.

  The image forming unit 40 includes a plurality of sets of image forming units 40Y, 40M, 40C, and 40K, an endless intermediate transfer belt 407, a transport unit 420 that transports the fed paper, and toner transferred to the paper. And a fixing unit 413 for fixing the image.

  The image forming unit 40Y for forming a yellow (Y) image includes a photosensitive drum 401Y as an image carrier, a developing unit 402Y, a charger 403Y disposed around the photosensitive drum 401Y, and a laser unit 404Y. And a cleaner 405Y and a primary transfer roller 406Y.

  Similarly, the image forming unit 40M that forms a magenta (M) color image includes a photosensitive drum 401M, a developing device 402M, a charger 403M, a laser unit 404M, a cleaner 405M, and a primary transfer roller 406M. I have.

  Similarly, the image forming unit 40C for forming a cyan (C) color image includes a photosensitive drum 401C, a developing unit 402C, a charger 403C, a laser unit 404C, a cleaner 405C, and a primary transfer roller 406C. I have.

  Similarly, the image forming unit 40K that forms a black (K) image includes a photosensitive drum 401K, a developing unit 402K, a charging unit 403K, a laser unit 404K, a cleaner 405K, and a primary transfer roller 406K. I have.

  Here, an image forming operation in the image forming unit 40 will be described. First, in the image forming unit 40Y, the photosensitive drum 401Y rotates, the surface thereof is charged by the charger 403Y, and the latent image of the Y data image is formed on the charged portion by the exposure of the laser light source output from the laser unit 404Y. It is formed. The latent image portion is developed by the developing device 402Y to form a yellow toner image. The toner image is primarily transferred to the intermediate transfer belt 407 by the pressure contact of the primary transfer roller 406Y. The toner image is a yellow image corresponding to the image data to be output. The toner that has not been primarily transferred is removed by the cleaner 405Y.

  Similarly, in the image forming units 40M, 40C, and 40K, magenta toner images, cyan toner images, and black toner images are formed and transferred, respectively. The image forming unit 40 further includes a roller 408 and a secondary transfer roller 410. The intermediate transfer belt is rotated by the rotation of the roller 408 and the secondary transfer roller 410 and the primary transfer rollers 406Y, 406M, 406C, and 406K. 407 is circulated. Then, the intermediate transfer belt 407 is rotated so that the YMCK toner images are sequentially superimposed on the intermediate transfer belt 407 and transferred.

The sheet feeding unit 50 includes sheet feeding trays 500A, 500B, and 500C, and sheet feeding rollers 501A, 501B, and 501C for conveying the sheets stored in the sheet feeding trays 500A to 500C to the conveying unit 420. For example, B5 size paper, A4 size paper, and A3 size paper are stored in the paper feed trays 500A to 500C, respectively. The paper feed trays 500A to 500C are provided with paper width defining portions 502A, 502B, and 502C, respectively. The sheet width defining sections 502A to 502C can change the position in the depth direction, and define the width of the sheets stored in the sheet feeding trays 500A to 500C. Further, the sheet width defining sections 502A to 502C output signals corresponding to the positions.
When the image forming unit 40 forms an image on a sheet, the sheet is conveyed one by one from any of the sheet feeding trays 500A to 500C by rotation of any of the sheet feeding rollers 501A to 501C. It is conveyed to the secondary transfer roller 410 by the rotation of the registration roller 409.

  When the sheet passes through the pressure contact portion of the secondary transfer roller 410, the YMCK toner image on the intermediate transfer belt 407 is secondarily transferred to the sheet. The sheet on which the YMCK toner image is transferred passes through the fixing unit 413.

  The fixing unit 413 includes a heating roller 413a, a fixing roller 413b, a fixing belt 413c, and a pressure roller 413d. The fixing belt 413c is stretched by a heating roller 413a and a fixing roller 413b. The heating roller 413a includes a high-power heater therein, rotates in the forward direction with respect to the paper transport direction, and heats the fixing roller 413b via the fixing belt 413c. The temperature of the fixing roller 413b is preferably set to a temperature necessary for ensuring the fixability. In the present embodiment, the temperature is set to 170 ° C., for example. The fixing roller 413b rotates in the forward direction with respect to the transport direction of the paper S, and heats and pressurizes the fixing surface of the transported paper. The pressure roller 413d presses the non-fixing surface of the paper that has been rotated and conveyed in the forward direction with respect to the paper conveyance direction. The fixing unit 413 is configured as described above, and pressurization and heating are performed on the paper, whereby the YMCK toner image is fixed on the paper. The paper on which the toner image is fixed is discharged by a paper discharge roller 417. In the present embodiment, the fixing unit 413 may be referred to as a fixing device.

  When forming an image on both sides, a sheet on which an image is formed on one side (front side) is sent to the duplex conveyance unit 415 by the conveyance path switching plate 414 and the surface is reversed by the duplex conveyance unit 415. Then, the sheet is conveyed to the secondary transfer roller 410 by the registration roller 409 so that the image is formed again on the surface where the image is not formed (back surface), and the image is formed. The paper on which images are formed on both sides and the toner is fixed is conveyed to a paper discharge tray 419 by a paper discharge roller 417. In the present embodiment, a flow path through which a sheet is conveyed by the registration roller 409, the secondary transfer roller 410, the duplex conveyance unit 415, the discharge roller 417, and the like is referred to as a conveyance unit 420.

  In the present exemplary embodiment, a surface processing unit 60 is provided on the downstream side of the fixing unit 413 to heat the surface of the paper that has been pressed and heated by the fixing unit 413 to perform surface processing. The surface treatment unit 60 performs surface treatment by heating the surface of the paper to give gloss to the surface of the paper. As shown in FIG. 2, the surface treatment unit 60 is disposed on the upper surface side of the conveyance unit 420, and a plurality of heating elements 60 a are arranged in a one-dimensional array in a direction (main scanning direction) orthogonal to the conveyance direction of the paper S. Is arranged. The plurality of heating elements 60a may be arranged in a two-dimensional array in the main scanning direction and the sub-scanning direction. The surface treatment unit 60 can selectively give gloss to the entire area of the sheet or an arbitrary partial area by individually controlling the energization of the plurality of heating elements 60a. The heating element 60a generates heat when a current is applied thereto, and the amount of heat applied to the paper can be adjusted by varying the amount of current as shown in FIG.

  After the image formation on the paper, the toner remaining on the intermediate transfer belt 407 is removed by the belt cleaning 412. Further, a positive polarity current and a negative polarity current are alternately switched from a power source (not shown) to the secondary transfer roller 410 and flow for a predetermined time, so that the toner remaining on the secondary transfer roller 410 is transferred to the intermediate transfer belt 407. The transfer is performed again, and the secondary transfer roller 410 is cleaned.

  Next, the configuration of the control system of the image forming apparatus 1 will be described. As shown in FIG. 4, the image forming apparatus 1 includes a control unit 10, an HDD (Hard Disk Drive) 14, an operation in addition to the image reading unit 30, the image forming unit 40, the paper feeding unit 50, and the surface processing unit 60 described above. A display unit 20 and a communication unit 70 are provided.

  The HDD 14 stores various data according to instructions from the control unit 10.

  The operation display unit 20 includes, for example, an LCD (Liquid Crystal Display), a touch panel, a numeric keypad, and the like. The operation display unit 20 configured as described above receives a display signal from the control unit 10 and displays it on the LCD, and outputs an operation signal input from a touch panel or a numeric keypad to the control unit 10.

  The communication unit 70 is an interface that can be connected to a transmission medium connected to a communication network N such as a LAN (Local Area Network) or a WAN (Wide Area Network). The communication unit 70 is configured by a communication control card such as a LAN card, for example, and transmits / receives various data to / from an external device such as a host device connected to the communication network N via a communication line with a LAN cable. .

  The control unit 10 includes a CPU (Central Processing Unit) 11, a RAM (Random Access Memory) 12, a ROM (Read Only Memory) 13, and the like. Various processing programs are stored in the ROM 13, and the CPU 11 reads out various programs stored in the ROM 13, develops them in the RAM 12, and controls the operation of each unit of the image forming apparatus 1 according to the expanded programs. Further, the control unit 10 can receive the signals from the sheet width defining units 502A to 502C, and can detect the widths or the sheet sizes of the sheets stored in the sheet feeding trays 500A to 500C based on the received signals.

  For example, when image data is input from the image reading unit 30 or the communication unit 70, the control unit 10 performs various image processing on the input image data and outputs the image data to the image forming unit 40 for each page, thereby forming an image. To do. Examples of the image processing include conversion processing of R, G, B image data input from the image reading unit 30 into Y, M, C, K image data, a host device (not shown) via the communication unit 70, and the like. For example, a process of converting image data included in the job data input from the image data into Y, M, C, and K image data in a data format that can be formed by the image forming apparatus 1 using a predetermined page description language. The job data includes paper size information indicating the paper size on which image formation is performed, and the control unit 10 can determine the width of the paper to be fed based on the paper size information. The paper is fed by selecting one of the paper feed trays 500A to 500C of the paper feed unit 50 so that an image is formed on the paper having the size indicated by.

  Next, the theory that gloss unevenness occurs in the image forming apparatus configured as described above will be described.

  For example, as shown in FIG. 5, a case where a plurality of sheets (PS1, PS2, PL3) having different sheet widths are passed will be described. Here, the sheets PS1 and PS2 are, for example, B5 size sheets, and the sheet PL3 is, for example, an A3 size sheet.

  First, when the sheets PS1 and PS2 as the first width sheets pass through the fixing unit 413, heat is taken away by the sheets PS1 and PS2 in the area through which the sheet of the fixing roller 413b passes. The positions where the sheets PS1 and PS2 are not in contact with each other may not be deprived of heat and become high temperature. For example, the temperature at the center of the fixing roller 413b may be 170 ° C., whereas the temperature at the end may rise to 190 to 200 ° C. Therefore, when the paper PL3 as the second width paper having a paper width larger than that of the paper PS1 and PS2 passes through the fixing unit 413, the heat of the paper PL3 is taken by the paper PS1 and PS2 of the fixing roller 413b. The amount of heat applied to the sheet PL3 differs between the position indicated by A and the position indicated by B in FIG. Here, the temperature distribution of the fixing roller 413b at P in FIG. 5 is shown in FIG. According to this, it can be seen that the area through which the sheets PS1 and PS2 having a small sheet width pass has a lower temperature than the other areas. Note that the positions indicated by A and B in FIG. 6 correspond to the positions indicated by A and B in FIG. 5, respectively.

  Next, the temperature transition of the fixing roller 413b of the fixing unit 413 will be described with reference to FIG. In addition, the graph shown by A and B in FIG. 7 has shown transition of the temperature in the position shown by A and B in FIG. 5, respectively. As shown in FIG. 7, for example, a plurality of B5 size sheets as an example of a first width sheet are passed through the fixing unit 413 and then an A3 size sheet as an example of a second width sheet. When a plurality of sheets are passed, the temperature in the surface of the sheet is uniform at the temperature indicated by A in FIG. 7 while the B5 size sheet is being passed, and gloss unevenness does not occur. When a plurality of sheets of paper are passed and then A3 size paper is passed, a temperature difference occurs between the central portion and the end portion of the paper, and uneven gloss (gloss level difference) occurs in this portion. Thereafter, the heat at the end of the fixing roller 413b is gradually taken away by the contact of the A3 size paper, and the temperature becomes the same as the position at the center, and the gloss unevenness is converged.

  Therefore, in the present embodiment, the paper is partially heated by causing the surface treatment unit 60 to partially generate heat, thereby reducing uneven gloss in the surface of the paper. That is, as shown in FIG. 8, the control unit 10 determines whether or not to change the paper to be passed (step S101). When the control unit 10 determines that the paper size to be passed is changed (step S101: Y), is the paper width after the change larger than the paper width before the paper size to be passed is changed? It is determined whether or not (step S102). When it is determined that the width of the paper after the change is larger than the width of the paper before the change of the paper size for passing the paper (step S102: Y), the surface processing unit 60 performs the heating process (step S103). For example, when a plurality of B5 size sheets are passed through the fixing unit 413 and then A3 size sheets are passed, as shown in FIG. 9, A3 at point P immediately after passing through the fixing unit 413. As described above, the amount of heat applied to the size paper varies depending on the region. Therefore, the glossiness at the center portion shown in A in FIG. 9 is different from the glossiness at the end portion shown in B, and gloss unevenness occurs. Therefore, in the heat treatment described above, the heating element 60a corresponding to the portion through which the B5 size paper of the surface treatment unit 60 provided at the position indicated by the point Q in FIG. 9 passes is heated to a predetermined temperature. Thereby, the glossiness at the position at the center can be made the same as the glossiness at the position at the edge, and the gloss in the plane of the paper becomes uniform.

  Further, as described above, when a plurality of B3 size sheets are passed through the fixing unit 413 and then a plurality of A3 size sheets are passed, the heat at the end of the fixing roller 413b is increased by the A3 size sheet. It is gradually deprived by contact and has a temperature similar to that at the center. Therefore, in the present embodiment, when a plurality of A3 size sheets are passed after a plurality of B5 size sheets are passed through the fixing unit 413, the heat generation temperature of the heating element 60a of the surface processing unit 60 is reached. Is reduced for each sheet. Specifically, as shown in FIG. 10, when a plurality of B5 size sheets are passed through the fixing unit 413 and the first A3 size sheet is passed, the first A3 size sheet is passed. The heating temperature when the heating element 60a of the surface treatment unit 60 heats the paper is a ° C. (eg, 140 ° C.). Subsequently, when the second A3 size sheet is passed through the fixing unit 413, the heat generation temperature when the heating element 60a of the surface processing unit 60 heats the second A3 size sheet is set as follows. The temperature is set to b ° C. (for example, 110 ° C.) lower than a ° C. Subsequently, when the third A3 size sheet is passed through the fixing unit 413, the heat generation temperature when the heating element 60a of the surface processing unit 60 heats the third A3 size sheet is set as follows. It is set as c degree C (for example, 100 degree C) lower than b degree C. Thereafter, the temperature at the center and the end of the fixing roller 413b of the fixing unit 413 becomes uniform, so that the sheet is not heated by the surface processing unit 60.

  Then, as shown in FIG. 11, even when the heat at the end portion of the fixing roller 413b is decreased for each sheet passing, it is understood that uneven glossiness between the center portion and the end portion in the sheet surface is suppressed. Here, A in FIG. 11 represents the glossiness at the center of the paper, and B represents the glossiness at the edge of the paper.

  As described above, according to the present embodiment, the image forming unit 40 forms a toner image on a sheet. The fixing unit 413 fixes the toner image on the sheet by heating and pressing the sheet on which the toner image is formed by the image forming unit 40 with a heating member and a pressing member. The surface treatment unit 60 performs surface treatment of the paper by selectively heating an area to be heated for the paper fixed by the fixing unit 413. The control unit 10 detects the width of the sheet on which the toner image is formed by the image forming unit 40. When the control unit 10 determines that the fixing by the fixing unit 413 is changed from the first width sheet to the second width sheet larger than the first width based on the detection result, The surface processing unit 60 is controlled to heat the area of the second width paper corresponding to the position where the paper of the width of the second paper passes through the fixing unit 413. As a result, it is possible to reduce uneven glossiness that occurs when the width of the paper to be passed is changed.

  Further, according to the present embodiment, when the surface processing is performed by the surface processing unit 60 on the plurality of sheets having the second width, the control unit 10 performs the surface processing of the surface processing unit 60 each time the surface processing is performed on the paper. Reduce the heating temperature. As a result, it is possible to suppress the occurrence of uneven glossiness when the temperature of the high temperature portion in the fixing unit is lowered due to the sheet passing.

  The description in the embodiment of the present invention is an example of the image forming apparatus according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of each functional unit constituting the image forming apparatus can be appropriately changed.

  In this embodiment, the heating member is configured by the heating roller 413a, the fixing roller 413b, and the fixing belt 413c. However, the heating member is configured by the heating roller, and the heating roller and the pressure roller add to the paper. The structure which implements a pressure and a heating may be sufficient.

  In this embodiment, the width of the sheet on which the toner image is formed is detected based on the signals from the sheet width defining units 502A to 502C. For example, the sheet size is manipulated for each sheet feeding tray. It is also possible to detect the width of the sheet by inputting it through the display unit 20 and setting it individually. Further, for example, it may be realized by providing a line sensor or the like in the transport unit 420 and detecting the width of the paper transported through the transport unit 420.

  Further, in the present embodiment, any size paper is configured to be transported by the transport unit 420 so that the center of the paper is at the same position (that is, the non-loading of the paper in the transport unit 420). (The passing part is even on the left and right, and the non-passing part changes equally on the left and right according to the paper size), but the left and right edges of the paper are transported to the same position regardless of the paper size. The sheet is transported by the unit 420 (that is, the left or right of the non-passing part of the sheet in the transport unit 420 is configured to change according to the size of the sheet). Also good. That is, for example, for any size paper, the left end of the paper may be conveyed at the same position.

  In the present embodiment, the surface treatment unit 60 is controlled by software processing by the control unit 10, but the control may be performed by a hardware configuration such as an ASIC (Application Specific Integrated Circuit). .

  In this embodiment, a color image forming apparatus that forms a toner image on a sheet with four color toner materials of CMYK is applied. However, the present invention is applied to an image forming apparatus that forms a toner image on a sheet with a single color toner material. Also good.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Control part 40 Image forming part 413 Fixing part (fixing apparatus)
413b Fixing roller (heating member)
413d Pressure roller (pressure member)
60 Surface treatment section 502A, 502B, 502C Paper width defining section

Claims (6)

The sheet on which the toner image is formed is heated and pressed by a heating member and a pressure member, so that a region to be heated with respect to the sheet that has passed through a fixing device that fixes the toner image on the sheet is selectively heated. A surface treatment unit for performing surface treatment;
The width of the sheet on which the toner image is formed is detected, and based on the detection result, the fixing by the fixing device is changed from the first width sheet to the second width sheet larger than the first width. A control unit that controls the surface treatment unit to heat a region of the second width paper corresponding to a position where the first width paper passes through the fixing device when it is determined that
A surface treatment apparatus comprising:   When the surface treatment is performed by the surface treatment unit on the plurality of sheets having the second width, the control unit reduces the heating temperature of the surface treatment unit every time the surface treatment is performed on the paper. The surface treatment apparatus according to claim 1. An image forming unit for forming a toner image on paper;
A fixing unit that fixes the toner image on the sheet by heating and pressing the sheet on which the toner image is formed by the image forming unit with a heating member and a pressing member;
A surface treatment unit for selectively heating a region to be heated with respect to the paper fixed by the fixing unit and performing surface treatment of the paper;
A width of a sheet on which a toner image is formed by the image forming unit is detected, and based on the detection result, a second width in which fixing by the fixing unit is larger than the first width from the first width sheet Control to cause the surface treatment section to heat the area of the second width sheet corresponding to the position where the first width sheet passes through the fixing unit when it is determined that the sheet has been changed to the first sheet. A control unit to perform,
An image forming apparatus comprising:   When the surface treatment is performed by the surface treatment unit on the plurality of sheets having the second width, the control unit reduces the heating temperature of the surface treatment unit every time the surface treatment is performed on the paper. The image forming apparatus according to claim 3. An image forming step of forming a toner image on paper;
A fixing step of fixing the toner image on the paper by heating and pressurizing the paper on which the toner image is formed in the image forming step with a heating member and a pressure member of a fixing device;
A surface treatment step of performing surface treatment of the paper by selectively heating an area to be heated to the paper fixed in the fixing step;
Including
In the surface treatment step, when the fixing by the fixing device is changed from a first width sheet to a second width sheet larger than the first width, the first width sheet is fixed. An image forming method, comprising: heating an area of the second width paper corresponding to a position passing through the apparatus.   In the surface treatment step, when the surface treatment by the surface treatment unit is performed on a plurality of sheets having the second width, the heating temperature is lowered every time the surface treatment is performed on the sheets. 6. The image forming method according to 5.

Images