JP2018040863A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust the position of a fixation unit with respect to a transfer unit in an image formation apparatus.SOLUTION: An image formation apparatus includes: a fixation unit 18 which fixes a toner image transferred by a transfer roller 175 on a sheet P with a nip part formed between a fixation roller 181 and a pressure roller 182; and sensors 20F, 20R which are provided between the transfer roller 175 and the fixation unit 18 and detect the position of the sheets P. The image formation apparatus separates the fixation roller 181 from the pressure roller 182, stops conveyance of the sheets P after conveying the sheets P to the space between the transfer roller 175 and the fixation unit 18, brings the fixation roller 181 into pressure-contact with the pressure roller 182 in a state where the tension is applied to the sheets P, acquires the detection result of the positions of the sheets P from the sensors 20F, 20R in this state, and adjusts the position of the fixation unit 18 with respect to the transfer roller 175 on the basis of the acquired detection result at the conveyance stop.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  Conventionally, in an electrophotographic image forming apparatus, 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 An image is formed on a sheet by fixing the image on the sheet.

  The positional relationship between the transfer unit and the fixing unit is affected by assembly errors and variations in the dimensions of the roller members. For example, when the distance between the transfer roller and the fixing roller is different between the front side and the back side of the apparatus, the loop becomes large on one side in the width direction of the paper, and wrinkles and image displacement occur. FIG. 19 shows an example in which a loop occurs on the paper P between the transfer roller 31 and the fixing roller 32. When the unfixed toner on the paper P comes into contact with the fixing roller 32 in front of the nip portion N1 of the fixing roller 32, an image shift occurs. Also, as shown in FIG. 20, unfixed toner on the paper P is fixed even when the height of the nip portion N2 of the transfer roller 31 and the nip portion N1 of the fixing roller 32 do not match a predetermined state. Contact with the fixing roller 32 in front of the nip portion N1 of the roller 32 causes image displacement.

  For this reason, it is necessary to adjust the position of the fixing unit with respect to the transfer unit during the assembly process or replacement of the fixing unit. Since manual adjustment of the position of the fixing unit is time-consuming, a sensor for detecting the paper position is provided between the transfer unit and the fixing unit, and based on the detection result of the paper position at the time of fixing (paper conveyance). An image forming apparatus that automatically adjusts the position of the fixing unit has been proposed (see Patent Document 1).

  FIG. 21B is a top view illustrating an example of the peripheral configuration of the transfer roller 41 and the fixing roller 42 in the conventional image forming apparatus. FIG. 21A is an end view taken along line A11-A11 in FIG. 21B, and FIG. 21C is an end view taken along line C11-C11 in FIG. Sensors 43F and 43R for detecting the position of the paper are provided near both ends in the paper width direction between the transfer roller 41 and the fixing roller 42. Each of the sensors 43F and 43R detects the distance from the sensors 43F and 43R to the paper P when the paper is conveyed (when the fixing roller 42 is driven). As shown in FIG. 21B, when the distance between the transfer roller 41 and the fixing roller 42 is shorter on the back side than on the front side in the paper width direction, the paper P bends to the back side during conveyance, and the paper on the back side. A loop occurs. For this reason, the paper P approaches the sensor 43R on the back side, and the distance between the sensors 43F and 43R and the paper P is shorter on the back side. Based on this detection result, the fixing roller 42 is rotated with the Rz axis orthogonal to the paper surface shown in FIG. 21B as the rotation axis, so that the axial direction of the transfer roller 41 and the axial direction of the fixing roller 42 are parallel to each other. To do.

JP 2002-40865 A

However, depending on the positional relationship between the transfer unit and the fixing unit, it may be difficult to accurately adjust the position of the fixing unit with respect to the transfer unit.
FIG. 22B is a top view illustrating another example of the peripheral configuration of the transfer roller 51 and the fixing roller 52 in the conventional image forming apparatus. 22A is an end view taken along the line A12-A12 in FIG. 22B, and FIG. 22C is an end view taken along the line C12-C12 in FIG. 22B. FIG. 22D is a view seen from the direction of the arrow D2 shown in FIG. Sensors 53F and 53R for detecting the position of the paper are provided near both ends in the paper width direction between the transfer roller 51 and the fixing roller 52. 22A, 22C, and 22D, when the rear side of the fixing roller 52 is installed at a higher position than the front side, the sensors 53F and 53R and the paper P The distance is shorter on the far side, but no paper loop occurs.

Even in such a case, as in the case shown in FIGS. 21A to 21C, if the fixing roller is rotated with the Rz axis orthogonal to the paper surface as the rotation axis, a paper loop is generated. Cause.
The difference in the distance between the sensor and the paper at both ends in the paper width direction is due to a paper loop as shown in FIGS. 21A to 21C, or a fixing portion as shown in FIGS. 22A to 22D. Therefore, it is difficult to adjust the positional relationship between the transfer portion and the fixing portion.

  The present invention has been made in view of the above-described problems in the related art, and an object of the present invention is to easily adjust the position of the fixing unit with respect to the transfer unit in the image forming apparatus.

  In order to solve the above-described problem, the invention according to claim 1 is characterized in that the transfer is performed by a transfer portion that transfers an unfixed toner image onto a sheet, and a nip portion that is formed by a first member and a second member. Provided at different positions in the paper width direction between the fixing unit for fixing the toner image on the paper, the conveyance unit for nipping and conveying the paper, and the transfer unit and the fixing unit. Two or more sheet position detection units that detect the position of the sheet in the direction, a position adjustment unit that adjusts the position of the fixing unit with respect to the transfer unit, and a pressure-bonding separation that crimps and separates the first member and the second member. The first member and the second member are separated from each other, and the conveyance unit is controlled to convey the sheet between the transfer unit and the fixing unit. After that, stop transporting the paper and make sure that the paper is under tension. Then, by controlling the pressure-bonding / separating portion, the first member and the second member are pressure-bonded, and in this state, the detection result of the paper position is acquired from the paper-position detecting portion, and the acquired conveyance is performed. An image forming apparatus comprising: a control unit that controls the position adjustment unit based on a detection result at the time of stop.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the position adjustment unit includes a first adjustment unit that rotates the fixing unit about a sheet conveyance direction as a rotation axis, and the control unit. Controls the first adjustment unit based on the detection result when the conveyance is stopped, and adjusts the position of the fixing unit so that the axial direction of the fixing unit and the axial direction of the transfer unit are parallel to each other. It is characterized by adjusting.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the position adjustment unit includes a second adjustment unit that moves the fixing unit in a direction perpendicular to a sheet surface, The control unit controls the second adjustment unit based on the detection result when the conveyance is stopped, so that the fixing unit is in a predetermined position in a direction perpendicular to the sheet surface. The position is adjusted.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the control unit further controls the pressure-bonding / separating unit to control the first member and the first unit. In the state where the two members are pressed together, the conveyance unit is controlled to convey the sheet, and when the fixing unit performs fixing, the detection result of the sheet position is acquired from the sheet position detection unit, and the acquisition is performed. The position adjusting unit is controlled based on the detection result when the fixing is performed and the detection result when the conveyance is stopped.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the position adjustment unit includes a third adjustment unit that rotates the fixing unit about a direction perpendicular to the sheet surface as a rotation axis. The control unit controls the third adjustment unit based on the detection result when the conveyance is stopped and the detection result when the fixing is performed, and the axial direction of the fixing unit and the axial direction of the transfer unit are parallel to each other. The position of the fixing unit is adjusted so that

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the image forming apparatus further includes a speed adjusting unit that adjusts a fixing speed in the fixing unit, and the control unit further includes: In the state where the crimping separation unit is controlled so that the first member and the second member are crimped, the conveyance unit is controlled so that the sheet is conveyed, and when the fixing is performed by the fixing unit, the sheet The sheet position detection result is acquired from the position detection unit, and the speed adjustment unit is controlled based on the acquired detection result at the time of fixing and the detection result at the time of the conveyance stop.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, two of the two or more paper position detecting units are opposed to a sheet surface. It is provided in a direction and is at substantially the same distance from the center in the paper width direction.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the control unit is configured to change the position at the time of replacement of the fixing unit and every predetermined use count. The adjustment unit is caused to perform an adjustment operation.

  According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, when the adjustment amount by the position adjustment unit after the fixing unit is replaced exceeds a predetermined amount, The adjustment operation by the position adjustment unit is stopped, and a display prompting replacement of the fixing unit is performed.

  According to the present invention, in the image forming apparatus, the position of the fixing unit with respect to the transfer unit can be easily adjusted.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a block diagram illustrating a main functional configuration of the image forming apparatus. FIG. It is a perspective view which shows the positional relationship of a transfer roller, a fixing roller, a pressure roller, and a sensor. 5 is a flowchart illustrating fixing unit adjustment processing executed by the image forming apparatus. It is a flowchart which shows a 1st detection mode process. (A) is a figure which shows the state by which the paper was conveyed to the position over a transfer roller and a fixing part in the state in which the fixing roller and the pressure roller were separated in the first detection mode process. FIG. 6B is a diagram illustrating a state where tension is applied to the paper between the transfer roller and the transport roller. (C) is a figure which shows the state by which the fixing roller and the pressure roller were crimped | bonded. FIG. 6D is a diagram illustrating a state in which a detection result of a paper position (detection result when transport is stopped) is acquired from a sensor. It is a flowchart which shows a 1st adjustment process. It is a schematic diagram for demonstrating a 1st adjustment part. It is a flowchart which shows a 2nd adjustment process. It is a schematic diagram for demonstrating a 2nd adjustment part. It is a flowchart which shows a 2nd detection mode process. (A) is a figure which shows the state in which a fixing roller and a pressure roller are crimped | bonded and fixing is performed in 2nd detection mode process. FIG. 6B is a diagram illustrating a state in which a detection result of a sheet position (detection result at the time of fixing) is acquired from a sensor. It is a flowchart which shows a 3rd adjustment process. It is a schematic diagram for demonstrating a 3rd adjustment part. It is a flowchart which shows a speed adjustment process. It is a schematic diagram for demonstrating a speed adjustment part. 10 is a flowchart illustrating a first modification of fixing unit adjustment processing. 12 is a flowchart illustrating a second modification of the fixing unit adjustment processing. It is a figure for demonstrating the problem in the conventional image forming apparatus. It is a figure for demonstrating the problem in the conventional image forming apparatus. This is an example in which the positional relationship between the transfer roller and the fixing roller does not match. This is another example in which the positional relationship between the transfer roller and the fixing roller does not match.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings. The present invention is not limited to the illustrated example.
FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 10 according to the present embodiment. FIG. 2 is a block diagram illustrating a main functional configuration of the image forming apparatus 10.

  The image forming apparatus 10 includes a control unit 11, an operation unit 12, a display unit 13, a communication unit 14, a storage unit 15, a scanner 16, an image forming unit 17, a fixing unit 18, a transport unit 19, a sensor 20, a position adjustment unit 21, A speed adjusting unit 22, a pressure separating / separating unit 23 and the like are provided. The control unit 11 is connected to each unit via a bus 24.

  The control unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. In response to an operation signal input from the operation unit 12 or an instruction signal received by the communication unit 14, the CPU reads a system program and various processing programs stored in the ROM or the storage unit 15 and expands them in the RAM. The operation of each part of the image forming apparatus 10 is centrally controlled according to the developed program.

The operation unit 12 includes a touch panel formed to cover the display screen of the display unit 13 and various operation buttons such as numeric buttons and a start button, and outputs an operation signal based on a user operation to the control unit 11.
The display unit 13 is configured by an LCD (Liquid Crystal Display), and displays various operation buttons, device status display, operation status of each function, and the like on the display screen in accordance with an instruction of a display signal input from the control unit 11. .
The communication unit 14 transmits / receives data to / from each device connected to a communication network such as a LAN (Local Area Network).

  The storage unit 15 is configured by a hard disk, a flash memory, or the like, and stores various data. The storage unit 15 stores a number counter, and is incremented by 1 each time one image is formed. In addition, the storage unit 15 stores in advance limit values (predetermined amounts) of adjustment amounts for adjustment by the position adjustment unit 21 (first adjustment unit 211, second adjustment unit 212, and third adjustment unit 213) and the speed adjustment unit 22. It is remembered. Further, the storage unit 15 stores adjustment amounts of adjustment by the first adjustment unit 211, the second adjustment unit 212, the third adjustment unit 213, and the speed adjustment unit 22 after the fixing unit 18 is replaced.

  The scanner 16 reads an image formed on the paper P, generates image data including single-color image data for each of red, green, and blue color components, and stores the image data in the storage unit 15.

  The image forming unit 17 forms an image on the paper P based on the image data stored in the storage unit 15. The image forming unit 17 includes four exposure units 171, a photosensitive drum 172, and a developing unit 173 that respectively correspond to color components of Y (yellow), M (magenta), C (cyan), and K (black). The image forming unit 17 includes an intermediate transfer belt 174 and a transfer roller 175.

The exposure unit 171 includes an LD (Laser Diode) as a light emitting element. The exposure unit 171 drives the LD based on the image data, irradiates the charged photosensitive drum 172 with laser light, and forms an electrostatic latent image on the photosensitive drum 172. The developing unit 173 supplies toner (coloring material) of a predetermined color (any of Y, M, C, and K) to the exposed photosensitive drum 172 by a developing roller, and forms it on the photosensitive drum 172. The developed electrostatic latent image is developed.
Images (monochromatic toner images) formed with Y, M, C, and K toners on the four photosensitive drums 172 corresponding to Y, M, C, and K are respectively transferred from the photosensitive drums 172 to the intermediate transfer belt 174. The images are sequentially superimposed and transferred (primary transfer). As a result, a color image (color toner image) having Y, M, C, and K as color components is formed on the intermediate transfer belt 174.

The intermediate transfer belt 174 is an endless belt wound around a plurality of transfer member conveyance rollers, and rotates according to the rotation of each transfer member conveyance roller.
The transfer roller 175 is a transfer unit that transfers an unfixed toner image formed on the intermediate transfer belt 174 onto a sheet P fed from a sheet feeding tray or a sheet feeding device provided outside (secondary transfer). Transcription).

The fixing unit 18 includes a fixing roller 181 as a first member and a pressure roller 182 as a second member. The fixing unit 18 heats and presses the paper P by a nip formed by the fixing roller 181 and the pressure roller 182, and fixes the toner image transferred by the transfer roller 175 onto the paper P.
The fixing roller 181 includes a halogen lamp heater extending in the rotation axis direction, and generates heat when energized under the control of the control unit 11. Further, the fixing roller 181 is driven to rotate by a rotation driving unit such as a motor (not shown) under the control of the control unit 11.

  The pressure roller 182 is urged in the direction approaching the fixing roller 181 by the pressure-bonding / separating portion 23 and is pressure-bonded to the fixing roller 181. Rotate.

  The transport unit 19 includes a plurality of transport rollers that rotate in a state where the paper P is sandwiched in addition to the transport roller 191 provided downstream of the fixing unit 18, and transports the paper P along a predetermined transport path.

  FIG. 3 is a perspective view showing a positional relationship among the transfer roller 175, the fixing roller 181 and the pressure roller 182 of the fixing unit 18, and the sensors 20 (20F, 20R).

A plurality of sensors 20F and 20R are provided at different positions in the paper width direction (Y-axis direction shown in FIG. 3) between the transfer roller 175 and the fixing unit 18. Specifically, a sensor 20F is provided on the front side in the paper width direction of the image forming apparatus 10, and a sensor 20R is provided on the back side. The sensors 20F and 20R are paper position detection units that detect the position of the paper P in the direction perpendicular to the paper surface (the Z-axis direction shown in FIG. 3). The sensors 20F and 20R are provided so as to face the sheet surface, and are disposed at both ends at substantially the same distance from the center in the sheet width direction. The sensors 20F and 20R detect the distance from the surface facing the paper surface of the sensors 20F and 20R to the paper surface. Hereinafter, when the sensors 20F and 20R are not distinguished, they are referred to as sensors 20.
A moving mechanism that moves the sensors 20F and 20R in the paper width direction according to the paper width may be provided.

The position adjustment unit 21 adjusts the position of the fixing unit 18 with respect to the transfer roller 175.
The position adjustment unit 21 includes a first adjustment unit 211, a second adjustment unit 212, and a third adjustment unit 213.

The first adjustment unit 211 rotates the fixing unit 18 with the sheet conveyance direction (X-axis direction shown in FIG. 3) as a rotation axis (Rx axis shown in FIG. 3). The first adjustment unit 211 is configured by a rotary actuator or the like.
The second adjustment unit 212 moves the fixing unit 18 in a direction perpendicular to the sheet surface (Z-axis direction shown in FIG. 3). The second adjustment unit 212 is configured by a linear actuator or the like.
The third adjustment unit 213 rotates the fixing unit 18 with a direction perpendicular to the sheet surface as a rotation axis (Rz axis shown in FIG. 3). The third adjustment unit 213 is configured by a rotary actuator or the like.

  The speed adjusting unit 22 adjusts the fixing speed in the fixing unit 18. Specifically, the speed adjustment unit 22 controls the rotation speed of the rotation driving unit that rotates the fixing roller 181 to adjust the speed at which the paper P is nipped and conveyed through the fixing unit 18.

  The pressure separating / separating unit 23 urges the pressure roller 182 against the fixing roller 181 to cause the fixing roller 181 and the pressure roller 182 to be pressure bonded. Further, the pressure separating / separating unit 23 separates the fixing roller 181 and the pressure roller 182.

  The control unit 11 controls the pressure-bonding / separating unit 23 to separate the fixing roller 181 and the pressure roller 182, and controls the transport unit 19 to transport the paper P between the transfer roller 175 and the fixing unit 18. Then, the conveyance of the paper P is stopped, and in a state where the tension is applied to the paper P, the pressure separating / separating portion 23 is controlled to press the fixing roller 181 and the pressure roller 182. In this state, the sensor 20F , 20R, the detection result of the position of the paper P is acquired (hereinafter referred to as first detection mode processing). The control unit 11 controls the position adjustment unit 21 based on the detection result at the time of conveyance stop acquired in the first detection mode process.

  When tension is applied to the paper P between the transfer roller 175 and the fixing unit 18, transport rollers provided upstream and downstream of the fixing unit 18 in the paper transport direction are used. In the state where the fixing roller 181 and the pressure roller 182 are separated from each other by the pressure-bonding / separating unit 23, the conveyance roller upstream or downstream of the fixing unit 18 is driven to apply tension to the paper P. In the present embodiment, a transfer roller 175 is used as a transport roller on the upstream side of the fixing unit 18, and a transport roller 191 is used as a transport roller on the downstream side of the fixing unit 18.

Specifically, the control unit 11 controls the first adjustment unit 211 based on the detection result at the time of conveyance stop, rotates the fixing unit 18 about the Rx axis, and fixes the fixing unit 18 (the fixing roller 181, The position of the fixing unit 18 is adjusted so that the axial direction of the pressure roller 182) and the axial direction of the transfer roller 175 are parallel to each other.
Further, the control unit 11 controls the second adjustment unit 212 based on the detection result when the conveyance is stopped, so that the fixing unit 18 is in a predetermined position in a direction (Z-axis direction) perpendicular to the sheet surface. As described above, the position of the fixing unit 18 is adjusted.

  The control unit 11 further controls the pressure-bonding / separating unit 23 to control the transport unit 19 in a state where the fixing roller 181 and the pressure roller 182 are pressure-bonded, while transporting the paper P, and the fixing unit 18. When the fixing operation is performed, the detection result of the position of the paper P is acquired from the sensors 20F and 20R (hereinafter referred to as a second detection mode process). The control unit 11 controls the position adjustment unit 21 or the speed adjustment unit 22 based on the detection result at the time of fixing acquired in the second detection mode process and the detection result at the time of conveyance stop acquired in the first detection mode process. Control.

Specifically, the control unit 11 controls the third adjustment unit 213 on the basis of the detection result at the time of conveyance stop and the detection result at the time of fixing, and rotates the fixing unit 18 around the Rz axis to fix the image. The position of the fixing unit 18 is adjusted so that the axial direction of the unit 18 (the fixing roller 181 and the pressure roller 182) and the axial direction of the transfer roller 175 are parallel to each other.
Further, the control unit 11 controls the speed adjusting unit 22 based on the detection result at the time of conveyance stop and the detection result at the time of fixing, and adjusts the fixing speed in the fixing unit 18.

  The control unit 11 causes the position adjustment unit 21 to perform an adjustment operation when the fixing unit 18 is replaced and every predetermined usage count. The predetermined use count refers to a count value that accompanies the use of the image forming apparatus 10. For example, the control unit 11 causes the position adjustment unit 21 to perform an adjustment operation every predetermined number of adjustment intervals for the number of sheets P on which image formation is performed after the fixing unit 18 is replaced. Alternatively, the position adjustment unit 21 may perform an adjustment operation every predetermined time.

  When the adjustment amount by the position adjustment unit 21 after the replacement of the fixing unit 18 exceeds a predetermined amount, the control unit 11 stops the adjustment operation by the position adjustment unit 21 and displays a display prompting replacement of the fixing unit 18. Do. For example, when the silicone rubber of the fixing roller 181 and the pressure roller 182 deteriorates and the outer diameter and hardness of the roller change, the position of the nip portion changes. Therefore, the durable use limit of the fixing roller 181 and the pressure roller 182 is previously set. The amount of change and the adjustment amount (limit value) corresponding to the change amount are confirmed.

Next, the operation of the image forming apparatus 10 will be described.
FIG. 4 is a flowchart showing fixing unit adjustment processing executed by the image forming apparatus 10. This process is performed in the image forming apparatus 10 when the power is turned on or when printing is completed.

  First, the control unit 11 determines whether it is the adjustment timing of the fixing unit 18 (step S1). Specifically, the control unit 11 adjusts the adjustment timing when it is immediately after the fixing unit 18 is replaced or when the value of the number counter stored in the storage unit 15 is an integral multiple of the number of adjustment intervals. It is judged that.

  When it is the adjustment timing of the fixing unit 18 (step S1; YES), the control unit 11 performs a first detection mode process (step S2).

Here, the first detection mode process will be described with reference to FIG.
The control unit 11 controls the pressure-bonding / separating unit 23 to separate the fixing roller 181 and the pressure roller 182 (step S21).
Next, the control unit 11 controls the transport unit 19 to transport the paper P from the transfer roller 175 to the transport roller 191 downstream of the fixing unit 18, and stops the transport of the paper P (step S22). As a result, the paper P is passed between the transfer roller 175 and the fixing unit 18.
In FIG. 6A, the transfer roller 175 and the transport roller 191 are driven in a state where the fixing roller 181 and the pressure roller 182 are separated from each other, and the sheet P reaches the position straddling the transfer roller 175 and the fixing unit 18. Indicates the state of being conveyed.

Next, the controller 11 applies tension to the paper P by driving the transport roller 191 (step S23). The driving force of the transport roller 191 is set to a driving force that can hold the paper P (the paper P does not slip) at the transfer roller 175 that is stopped driving.
FIG. 6B shows a state where tension is applied to the paper P between the transfer roller 175 and the transport roller 191.

Next, the control unit 11 controls the pressure-bonding / separating unit 23 to pressure-bond the fixing roller 181 and the pressure roller 182 (step S24).
FIG. 6C shows a state where the fixing roller 181 and the pressure roller 182 are pressure-bonded in a state where tension is applied to the paper P. At this time, the driving of the fixing roller 181 and the conveyance of the paper P are stopped.

Next, as shown in FIG. 6D, the control unit 11 acquires the detection result of the position of the paper P from the sensor 20 (detection result when the conveyance is stopped) (step S25). At this time, the detection result (the distance from the sensor 20F to the paper P) of the front sensor 20F is SF, and the detection result of the back sensor 20R (the distance from the sensor 20R to the paper P) is SR.
Thus, the first detection mode process ends. In the first detection mode process, since the fixing unit 18 is not driven, a paper loop does not occur between the transfer roller 175 and the fixing unit 18, and the inclination of the fixing nip portion around the Rx axis from the position of the paper P, The misalignment in the Z-axis direction is known.

  Returning to FIG. 4 after the first detection mode process, the control unit 11 performs the first adjustment process based on the detection result at the time of the conveyance stop acquired in the first detection mode process (step S3). The first adjustment process is a position adjustment process in which the first adjustment unit 211 rotates the fixing unit 18 about the Rx axis.

Here, the first adjustment process will be described with reference to FIG.
The control unit 11 compares the detection result SF of the near side sensor 20F when the conveyance is stopped with the detection result SR of the back side sensor 20R when the conveyance is stopped (step S31).
FIG. 8 is a schematic diagram of the transfer roller 175, the fixing roller 181, the pressure roller 182, and the sensors 20F and 20R viewed from the direction of the arrow D1 shown in FIG. The direction in which the fixing roller 181 and the pressure roller 182 are rotated clockwise around the Rx axis is defined as “+ direction”, and the direction in which the fixing roller 181 and the pressure roller 182 are rotated counterclockwise is defined as “− direction”.

When SF is larger than SR (step S31; SF> SR), the control unit 11 controls the first adjustment unit 211 to start rotation of the fixing unit 18 in the “+ direction” about the Rx axis. (Step S32).
As shown in FIG. 8, when the detection result SF of the front side sensor 20F is larger than the detection result SR of the back side sensor 20R, the fixing roller 181 and the pressure roller 182 are "+ direction" around the Rx axis. The difference between SF and SR is reduced by rotating to.

  Next, the control unit 11 determines whether or not the adjustment amount in the rotation around the Rx axis by the first adjustment unit 211 after the replacement of the fixing unit 18 exceeds the first predetermined amount (step S33). The first predetermined amount is a limit value of the adjustment amount in the “+ direction” in the rotation around the Rx axis by the first adjustment unit 211. When the adjustment amount by the first adjustment unit 211 is equal to or less than the first predetermined amount (step S33; NO), the process returns to step S31.

  In step S31, when SF is smaller than SR (step S31; SF <SR), the control unit 11 controls the first adjustment unit 211 to fix the fixing unit 18 in the “− direction” about the Rx axis. Is started (step S34).

  Next, the control unit 11 determines whether or not the adjustment amount in the rotation around the Rx axis by the first adjustment unit 211 after the replacement of the fixing unit 18 exceeds the second predetermined amount (step S35). The second predetermined amount is a limit value of the adjustment amount in the “− direction” in the rotation around the Rx axis by the first adjustment unit 211. When the adjustment amount by the first adjustment unit 211 is equal to or less than the second predetermined amount (step S35; NO), the process returns to step S31.

In step S31, when SF is equal to SR (step S31; SF = SR), the control unit 11 controls the first adjustment unit 211 to stop the rotation around the Rx axis (step S36).
This completes the first adjustment process.

  Returning to FIG. 4 after the first adjustment process, the control unit 11 performs the second adjustment process based on the detection result at the time of the conveyance stop acquired in the first detection mode process (step S4). The second adjustment process is a position adjustment process in which the second adjustment unit 212 moves the fixing unit 18 to a predetermined position in the Z-axis direction.

Here, the second adjustment processing will be described with reference to FIG.
The control unit 11 compares the detection result SF of the near side sensor 20F when the conveyance is stopped with the reference distance B (step S41). The reference distance B is a value indicating a reference sheet position, and is set in advance to a position where the sheet P does not contact the fixing roller 181 in front of the fixing nip portion in consideration of variations in sheet behavior.
FIG. 10 is a schematic diagram of the transfer roller 175, the fixing roller 181, the pressure roller 182, and the sensors 20F and 20R viewed from the direction of the arrow D1 shown in FIG. The direction in which the fixing roller 181 and the pressure roller 182 are moved upward along the Z axis is “+ direction”, and the direction in which the fixing roller 181 and pressure roller 182 are moved downward is “− direction”.

  When SF is larger than B (step S41; SF> B), the control unit 11 controls the second adjustment unit 212 to start moving the fixing unit 18 in the “+ direction” along the Z axis. (Step S42).

  Next, the control unit 11 determines whether or not the adjustment amount in the movement in the Z-axis direction by the second adjustment unit 212 after the replacement of the fixing unit 18 has exceeded a third predetermined amount (step S43). The third predetermined amount is a limit value of the adjustment amount in the “+ direction” in the movement in the Z-axis direction by the second adjustment unit 212. When the adjustment amount by the second adjustment unit 212 is equal to or smaller than the third predetermined amount (step S43; NO), the process returns to step S41.

In step S41, when SF is smaller than B (step S41; SF <B), the control unit 11 controls the second adjustment unit 212 to perform the fixing unit 18 in the “− direction” along the Z axis. Is started (step S44).
As shown in FIG. 10, when the detection result SF of the front sensor 20F is smaller than the reference distance B, the fixing roller 181 and the pressure roller 182 are moved in the “− direction” along the Z axis, SF approaches B.

  Next, the control unit 11 determines whether or not the adjustment amount in the movement in the Z-axis direction by the second adjustment unit 212 since the replacement of the fixing unit 18 has exceeded a fourth predetermined amount (step S45). The fourth predetermined amount is a limit value of the adjustment amount in the “− direction” in the movement in the Z-axis direction by the second adjustment unit 212. When the adjustment amount by the second adjustment unit 212 is equal to or less than the fourth predetermined amount (step S45; NO), the process returns to step S41.

In step S41, if SF is equal to B (step S41; SF = B), the control unit 11 controls the second adjustment unit 212 to stop the movement of the fixing unit 18 in the Z-axis direction (step S41). S46).
Thus, the second adjustment process ends.

  In FIG. 9, the case where the detection result SF of the near side sensor 20F is compared with the reference distance B in step S41 has been described. However, the detection result SR of the back side sensor 20R and the reference distance B are compared. It is good as well. In the first adjustment process, the adjustment has been completed so that SF = SR. Therefore, in the second adjustment process, SF = SR = B by adjusting SF = B.

  After the second adjustment process, returning to FIG. 4, the control unit 11 performs the second detection mode process (step S5).

Here, the second detection mode process will be described with reference to FIG.
The control unit 11 controls the pressure-bonding / separating unit 23 to control the transport unit 19 in a state where the fixing roller 181 and the pressure roller 182 are pressure-bonded, while transporting the paper P from the stopped state. The 18 fixing rollers 181 are driven (step S51).
FIG. 12A shows a state where the fixing roller 181 and the pressure roller 182 are pressure-bonded and fixing is executed.

Next, the control unit 11 acquires the detection result of the position of the paper P (detection result at the time of fixing) from the sensor 20 as shown in FIG. 12B after a predetermined time has elapsed from the start of conveyance (step S52). ). At this time, the detection result of the near-side sensor 20F is DF, and the detection result of the back-side sensor 20R is DR.
Thus, the second detection mode process ends. In the second detection mode process, the paper loop is known from the difference from the detection result when the conveyance is stopped.

  After the second detection mode process, the control unit 11 returns to the detection result at the time of carrying stop acquired in the first detection mode process and the detection result at the time of fixing execution acquired in the second detection mode process. Based on this, a third adjustment process is performed (step S6). The third adjustment process is a position adjustment process in which the third adjustment unit 213 rotates the fixing unit 18 around the Rz axis.

Here, the third adjustment process will be described with reference to FIG.
The control unit 11 compares SF-DF and SR-DR based on the detection results SF and SR of the sensors 20F and 20R when the conveyance is stopped and the detection results DF and DR of the sensors 20F and 20R at the time of fixing. (Step S61).
FIG. 14B is a top view showing the peripheral configuration of the transfer roller 175, the fixing roller 181 and the sensors 20F and 20R. 14A is an end view taken along the line A1-A1 in FIG. 14B, and FIG. 14C is an end view taken along the line C1-C1 in FIG. 14B. A direction in which the fixing roller 181 and the pressure roller 182 are rotated clockwise around the Rz axis is defined as “+ direction”, and a direction in which the fixing roller 181 and the pressure roller 182 are rotated counterclockwise is defined as “− direction”.

  When SF-DF is larger than SR-DR (step S61; SF-DF> SR-DR), the control unit 11 controls the third adjustment unit 213 to “+ direction” about the Rz axis. The rotation of the fixing unit 18 is started (step S62).

  Next, the control unit 11 determines whether or not the adjustment amount in the rotation around the Rz axis by the third adjustment unit 213 after the replacement of the fixing unit 18 exceeds the fifth predetermined amount (step S63). The fifth predetermined amount is a limit value of the adjustment amount in the “+ direction” in the rotation around the Rz axis by the third adjustment unit 213. When the adjustment amount by the third adjustment unit 213 is equal to or less than the fifth predetermined amount (step S63; NO), the process returns to step S61.

In step S61, if SF-DF is smaller than SR-DR (step S61; SF-DF <SR-DR), the control unit 11 controls the third adjustment unit 213 to center the Rz axis. The rotation of the fixing unit 18 is started in the “− direction” (step S64).
As shown in FIGS. 14A to 14C, assuming that the detection result SF of the front sensor 20F at the time of conveyance stop is equal to the detection result SR of the rear sensor 20R, the front sensor at the time of fixing is performed. When the detection result DF of 20F is larger than the detection result DR of the rear sensor 20R, SF-DF <SR-DR. In this case, the difference between DF and DR is reduced by rotating the fixing unit 18 in the “− direction” around the Rz axis.

  Next, the control unit 11 determines whether or not the adjustment amount in the rotation around the Rz axis by the third adjustment unit 213 after the replacement of the fixing unit 18 has exceeded the sixth predetermined amount (step S65). The sixth predetermined amount is a limit value of the adjustment amount in the “− direction” in the rotation around the Rz axis by the third adjustment unit 213. When the adjustment amount by the third adjustment unit 213 is equal to or less than the sixth predetermined amount (step S65; NO), the process returns to step S61.

In step S61, when SF-DF is equal to SR-DR (step S61; SF-DF = SR-DR), the control unit 11 controls the third adjustment unit 213 to rotate around the Rz axis. Stop (step S66).
Thus, the third adjustment process ends.

  After the third adjustment process, returning to FIG. 4, the control unit 11 is based on the detection result at the time of conveyance stop acquired in the first detection mode process and the detection result at the time of fixing execution acquired in the second detection mode process. Then, speed adjustment processing is performed (step S7). The speed adjustment process is a process for adjusting the fixing speed in the fixing unit 18 by the speed adjusting unit 22.

Here, the speed adjustment processing will be described with reference to FIG.
The control unit 11 compares SF-DF with 0 based on the detection result SF of the near side sensor 20F at the time of conveyance stop and the detection result DF of the near side sensor 20F at the time of fixing (step S71). ).
FIG. 16B is a top view showing the peripheral configuration of the transfer roller 175, the fixing roller 181 and the sensors 20F and 20R. 16A is an end view taken along the line A2-A2 of FIG. 16B, and FIG. 16C is an end view taken along the line C2-C2 of FIG. 16B. If the detection results DF and DR at the time of fixing are smaller than the detection results SF and SR at the time of conveyance stop, it means that a paper loop has occurred between the transfer roller 175 and the fixing unit 18.

If SF-DF is greater than 0 (step S71; SF-DF> 0), that is, if a paper loop has occurred, the control unit 11 controls the speed adjustment unit 22 to increase the fixing speed. Adjustment is started (step S72).
Assuming that the detection result SF of the near side sensor 20F at the time of conveyance stop is equal to the reference distance B, the detection result DF of the near side sensor 20F at the time of fixing is greater than the reference distance B as shown in FIG. If it is smaller, SF-DF = B-DF> 0. In this case, the difference between DF and B is reduced by increasing the fixing speed.

  Next, the control unit 11 determines whether or not the adjustment amount at the fixing speed by the speed adjusting unit 22 after the replacement of the fixing unit 18 exceeds a seventh predetermined amount (step S73). The seventh predetermined amount is a limit value of the adjustment amount in the adjustment of the fixing speed by the speed adjustment unit 22. When the adjustment amount by the speed adjustment unit 22 is equal to or less than the seventh predetermined amount (step S73; NO), the process returns to step S71.

In step S71, when SF-DF is 0 (step S71; SF-DF = 0), the control unit 11 controls the speed adjustment unit 22 to stop the adjustment to increase the fixing speed (step S74). .
This completes the speed adjustment process.

  In FIG. 15, the case has been described where, in step S <b> 71, SF-DF, which is the difference between the detection result at the time of conveyance stop by the front sensor 20 </ b> F, and the detection result at the time of fixing is compared with 0. It is also possible to compare SR-DR, which is the difference between the detection result at the time of conveyance stop in the sensor 20R and the detection result at the time of fixing, with zero. In the third adjustment process, adjustment has been completed so that SF-DF = SR-DR. Therefore, in the speed adjustment process, by adjusting SR-DR = 0, SF-DF = SR-DR = 0. Become.

  If the adjustment amount by the first adjustment unit 211 exceeds the first predetermined amount in step S33 (step S33; YES), if the adjustment amount by the first adjustment unit 211 exceeds the second predetermined amount in step S35 ( (Step S35; YES), when the adjustment amount by the second adjustment unit 212 exceeds the third predetermined amount in Step S43 (Step S43; YES), the adjustment amount by the second adjustment unit 212 is the fourth place in Step S45. When the fixed amount is exceeded (step S45; YES), when the adjustment amount by the third adjustment unit 213 exceeds the fifth predetermined amount at step S63 (step S63; YES), the third adjustment unit 213 at step S65. When the adjustment amount exceeds the sixth predetermined amount (step S65; YES), in step S73, the speed adjustment unit 22 If the adjustment amount exceeds a seventh predetermined amount (step S73; YES), returns to FIG. 4, the control unit 11 stops the control operation by the position adjusting section 21 or the speed adjusting unit 22 (step S8).

  Next, the control unit 11 causes the display unit 13 to display a message that prompts replacement of the fixing unit 18 (step S9). When the user opens the front door of the image forming apparatus 10, replaces the fixing unit 18 (step S10), and closes the front door, the control unit 11 resets the number counter stored in the storage unit 15 (step S11). ), The process returns to step S1.

  After step S7 or when it is not the adjustment timing of the fixing unit 18 in step S1 (step S1; NO), the control unit 11 sets the image forming apparatus 10 in a standby state.

  As described above, according to the image forming apparatus 10 of the present exemplary embodiment, the conveyance of the paper P is stopped in a state where the paper P has passed between the transfer roller 175 and the fixing unit 18, and the paper P is tensioned. In this state, the fixing roller 181 and the pressure roller 182 are pressure-bonded, and the detection result of the position of the paper P (detection result when the conveyance is stopped) is acquired from the sensors 20F and 20R, so that no paper loop occurs. Thus, the position of the fixing unit 18 with respect to the transfer roller 175 can be easily adjusted.

Specifically, the first adjusting unit 211 rotates the fixing unit 18 about the Rx axis, and the position of the fixing unit 18 is set so that the axial direction of the fixing unit 18 and the axial direction of the transfer roller 175 are parallel to each other. Can be adjusted.
Further, the position of the fixing unit 18 can be adjusted by the second adjustment unit 212 so that the second adjustment unit 212 has a predetermined position in the Z-axis direction.

  Further, since the detection result of the position of the paper P (detection result at the time of fixing execution) is acquired from the sensors 20F and 20R at the time of fixing by the fixing unit 18, the paper loop is eliminated from the difference from the detection result at the time of conveyance stop. Such adjustments can be made.

Specifically, the fixing unit 18 is rotated about the Rz axis by the third adjustment unit 213, and the position of the fixing unit 18 is set so that the axial direction of the fixing unit 18 and the axial direction of the transfer roller 175 are parallel to each other. Can be adjusted.
The first adjustment unit 211, the second adjustment unit 212, and the third adjustment unit 213 can accurately adjust the position of the fixing unit 18 with a simple configuration.
Further, the speed adjusting unit 22 can adjust the fixing speed to eliminate the paper loop.
With the above adjustment, the fixing unit 18 can be kept at an appropriate position, the posture of the paper P entering the fixing nip can be stabilized, and wrinkles of the paper P and image defects can be prevented.

  Further, by arranging the sensors 20F and 20R at substantially the same distance from the center in the paper width direction, the inclination of the paper P in the paper width direction can be detected with high accuracy.

  Further, when the fixing unit 18 is replaced, the fixing unit 18 is adjusted to an appropriate position, or the position of the fixing unit 18 is readjusted at every adjustment interval, thereby preventing wrinkles and image defects on the paper P. be able to.

  Further, when the adjustment amount by the position adjustment unit 21 after the fixing unit 18 is replaced exceeds a predetermined amount, the adjustment operation by the position adjustment unit 21 is stopped and a display prompting replacement of the fixing unit 18 is performed. By setting an adjustment amount corresponding to the life of the fixing roller 181 and the pressure roller 182 as a predetermined amount, the fixing unit 18 can be used to the maximum for its life and the running cost can be reduced.

  The description in the above embodiment 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 part constituting the apparatus can be changed as appropriate without departing from the spirit of the present invention.

  For example, in the above embodiment, the sensors 20F and 20R detect the first adjustment process (FIG. 7), the second adjustment process (FIG. 9), the third adjustment process (FIG. 13), and the speed adjustment process (FIG. 15). While the case where the position of the fixing unit 18 and the fixing speed are adjusted has been described, an adjustment amount corresponding to the degree of displacement and the degree of loop in each direction is obtained based on the detection results of the sensors 20F and 20R. It is good also as adjusting at once using.

In the above embodiment, the case where the two sensors 20F and 20R are provided has been described. However, the sheet width direction (Y-axis direction shown in FIG. 3) between the transfer roller 175 and the fixing unit 18 is described. Three or more sensors may be arranged at different positions.
Also, two or more sets of sensors 20F and 20R may be arranged along the paper transport direction (X-axis direction shown in FIG. 3).

  In the above embodiment, the case where the fixing roller 181 is used as the first member of the fixing unit 18 and the pressure roller 182 is used as the second member has been described. However, the first member and the second member are used in the fixing unit 18. Any member may be used as long as it forms a nip portion, and there is no limitation on the role of heating and pressurization of each member and the difference in shape such as a roller shape and a belt shape.

  Further, in the above-described embodiment, the case where the position adjustment of the fixing unit 18 is automatically performed when it is determined that it is the adjustment timing of the fixing unit 18 has been described. The position of the fixing unit 18 may be adjusted.

  Further, in the fixing unit adjustment processing shown in FIG. 4, not all the processing in steps S <b> 2 to S <b> 7 may be performed, but may be selectively performed according to the characteristics of the machine. For example, you may perform only the process of step S2-step S4. Specifically, depending on the arrangement configuration of the transfer roller 175 and the fixing unit 18, the direction in which the fixing unit 18 is likely to cause image defects differs depending on the adjustment direction that requires adjustment. The adjustment process to be adopted may be selected.

<Modification 1>
FIG. 17 is a flowchart illustrating Modification 1 of the fixing unit adjustment processing.
In the first modification, the first adjustment process (adjustment by rotation around the Rx axis) and the third adjustment process (adjustment by rotation around the Rz axis) are performed.
When it is the adjustment timing of the fixing unit 18 (step S81; YES), the control unit 11 performs the first detection mode process (step S82), and the detection result at the conveyance stop acquired in the first detection mode process is displayed. Based on this, the first adjustment process is performed (step S83).

Next, the control unit 11 performs the second detection mode process (step S84), the detection result at the conveyance stop acquired in the first detection mode process and the detection at the time of fixing execution acquired in the second detection mode process. Based on the result, a third adjustment process is performed (step S85).
The details of each process are the same as in the above embodiment. Further, the processing from step S86 to step S89 is the same as the processing from step S8 to step S11 in FIG.

<Modification 2>
FIG. 18 is a flowchart illustrating a second modification of the fixing unit adjustment processing.
In the second modification, a third adjustment process (adjustment by rotation around the Rz axis) is performed.
When it is the adjustment timing of the fixing unit 18 (step S91; YES), the control unit 11 performs the first detection mode process (step S92), performs the second detection mode process (step S93), and the first detection mode. The third adjustment process is performed based on the detection result at the time of conveyance stop acquired in the process and the detection result at the time of fixing acquired in the second detection mode process (step S94).
The details of each process are the same as in the above embodiment. Moreover, about the process of step S95-step S98, it is the same as that of the process of step S8-step S11 of FIG.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Control part 13 Display part 15 Memory | storage part 17 Image forming part 18 Fixing part 19 Conveyance part 20 Sensor 20F, 20R Sensor 21 Position adjustment part 22 Speed adjustment part 23 Crimp separation part 174 Intermediate transfer belt 175 Transfer roller 181 Fixing Roller 182 Pressure roller 191 Conveying roller 211 First adjustment unit 212 Second adjustment unit 213 Third adjustment unit P Paper

Claims (9)

A transfer unit for transferring an unfixed toner image onto the paper;
A fixing unit for fixing the transferred toner image on a sheet by a nip formed by the first member and the second member;
A conveyance unit for nipping and conveying the paper;
Two or more paper position detection units provided at different positions in the paper width direction between the transfer unit and the fixing unit and detecting the position of the paper in the direction perpendicular to the paper surface;
A position adjusting unit for adjusting the position of the fixing unit with respect to the transfer unit;
A crimping / separating portion for crimping and separating the first member and the second member;
Controlling the crimping separation part to separate the first member and the second member; and controlling the conveying part to convey the sheet between the transfer part and the fixing part; In the state in which the conveyance of the paper is stopped and the tension is applied to the paper, the crimping / separating portion is controlled so that the first member and the second member are pressure-bonded. A control unit that acquires a detection result of the paper position and controls the position adjustment unit based on the acquired detection result at the time of conveyance stop;
An image forming apparatus comprising: The position adjustment unit includes a first adjustment unit that rotates the fixing unit with a sheet conveyance direction as a rotation axis.
The control unit controls the first adjustment unit based on a detection result when the conveyance is stopped, so that the axial direction of the fixing unit and the axial direction of the transfer unit are parallel to each other. The image forming apparatus according to claim 1, wherein the position of the image forming apparatus is adjusted. The position adjustment unit includes a second adjustment unit that moves the fixing unit in a direction perpendicular to a sheet surface;
The control unit controls the second adjustment unit based on a detection result when the conveyance is stopped, so that the fixing unit is in a predetermined position in a direction perpendicular to the sheet surface. The image forming apparatus according to claim 1, wherein the position of the image forming apparatus is adjusted.   The control unit further controls the pressure-bonding / separating unit to control the conveyance unit in a state where the first member and the second member are pressure-bonded, while conveying the paper, and the fixing unit When the fixing is performed by the printer, the detection result of the sheet position is acquired from the sheet position detection unit, and the position adjustment unit is controlled based on the acquired detection result at the time of fixing execution and the detection result at the time of the conveyance stop. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The position adjustment unit includes a third adjustment unit that rotates the fixing unit about a direction perpendicular to the paper surface as a rotation axis.
The control unit controls the third adjustment unit based on the detection result when the conveyance is stopped and the detection result when the fixing is performed, and the axial direction of the fixing unit and the axial direction of the transfer unit are parallel to each other. The image forming apparatus according to claim 4, wherein the position of the fixing unit is adjusted so that A speed adjusting unit for adjusting a fixing speed in the fixing unit;
The control unit further controls the pressure-bonding / separating unit to control the conveyance unit in a state where the first member and the second member are pressure-bonded, while conveying the paper, and the fixing unit When the fixing is performed by the printer, a detection result of the paper position is acquired from the paper position detection unit, and the speed adjustment unit is controlled based on the acquired detection result at the time of fixing execution and the detection result at the time of the conveyance stop. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The two sheet position detection units among the two or more sheet position detection units are provided in a direction facing the sheet surface, and are substantially the same distance from the center in the sheet width direction. The image forming apparatus according to claim 1.   8. The image according to claim 1, wherein the control unit causes the position adjustment unit to perform an adjustment operation when the fixing unit is replaced and every predetermined use count. 9. Forming equipment.   When the adjustment amount by the position adjustment unit after the fixing unit is replaced exceeds a predetermined amount, the control unit stops the adjustment operation by the position adjustment unit and displays a display prompting replacement of the fixing unit. The image forming apparatus according to claim 8, wherein the image forming apparatus is performed.

Images