JP3561481B2 - Paper curl correcting device and image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
1. Field of the Invention The present invention relates to a sheet curl correcting device for correcting curl of a transfer sheet on which a toner image is formed, and an image forming apparatus including the same.
[0002]
[Prior art]
In an electrophotographic image forming apparatus such as an electronic copying machine or a laser printer, after a transfer sheet carrying a toner image is passed through a fixing device, a curl generated on the transfer sheet due to heat and pressure from a fixing roller is applied. Is provided with a paper curl straightening device for straightening the paper. As shown in FIG. 11 (a), this paper curl correcting device corrects curl by passing a transfer paper between a paper transport belt 90 and a pressing roll member 91 pressed by the belt. There has been proposed an apparatus having a configuration in which the pressing force of the pressing roll member 91 against the sheet conveying belt 90 can be changed by the rotation of 92. (2) As shown in FIG. 11B, the transfer paper is passed through the nip portion between the heat roller 95 and the pressure roller 96 to correct the curl, and the pressing lever 97 attached to the rotation shaft of the pressure roller 96 is used. Has been proposed in which the pressing force of the pressure roller 96 is changed by pulling the pressure upward by a solenoid 98.
[0003]
[Problems to be solved by the invention]
However, in the case of the above-described paper curling device (1), in order to stop the rotation of the cam 92 at a position where a desired pressing force is obtained, it is necessary to use a high-precision and expensive motor for rotating the cam 92. In addition, precision is required for the operation, and a complicated operation is required. Further, in the case of the paper curl correcting device of the above (2), if the state in which the pressing lever 97 is pulled by the solenoid 98 continues for a long time, the pulling force of the solenoid 98 may change due to a change in temperature of the electromagnet or the like. It is difficult to keep the pressing force between the roller 95 and the pressure roller 96 constant.
[0004]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and does not require precision in the operation of adjusting a driving roller and a pressure roller to a desired pressing force. It is an object of the present invention to provide a paper curl correcting device capable of stably maintaining a pressing force.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 has a drive roller and a pressure roller whose distance between rotation axes can be changed, and the transfer paper is passed through a nip portion between these two rollers. In a paper curl correction device for correcting curl, an opening provided with a plurality of holding portions capable of holding the rotation shafts of both rollers while maintaining a constant distance between the rotation shafts of the two rollers, There is a pressing force adjusting means movably configured to change a holding portion for holding the rotating shafts of both rollers, and the holding portion has a constant width in a moving direction of the pressing force adjusting means.
[0006]
According to this configuration, since the pressing force between the two rollers is adjusted by sandwiching the rotating shafts of the two rollers in the opening of the pressing force adjusting means, a constant pressing force can be stably maintained. Further, since the holding portion for holding the rotating shafts of the two rollers has a constant width in the moving direction of the pressing force adjusting means, the operation for obtaining the desired pressing force does not need to be precise. Moreover, this function can be obtained by a simple structure in which the rotation shafts of both rollers are sandwiched between the openings of the pressing force adjusting means, so that the device can be manufactured at low cost.
[0007]
According to a second aspect of the present invention, there is provided the sheet curling device according to the first aspect, wherein the pressing force adjusting unit is configured to be rotatable, and holds the rotating shafts of the two rollers by rotating. The holding portion is changed.
[0008]
According to this configuration, the pressing force adjusting means can be smoothly moved with respect to the rotation axis of the roller, and the structure that allows the pressing force adjusting means to be movable can be made compact.
[0009]
According to a third aspect of the present invention, in the paper curl correcting apparatus according to the first or second aspect, the driving roller has a fixed rotation axis position, and the pressure roller is provided with respect to the driving roller. The rotary shaft is movable in the direction of contact and separation.
[0010]
According to this configuration, since the rotation shaft position on the drive roller side to which the rotation drive force is transmitted is fixed, the reliability of the device is high, and the pressing force is applied with the rotation shaft of the fixed drive roller as the rotation center. The adjusting means can be rotated stably.
[0011]
According to a fourth aspect of the present invention, there is provided the sheet curl correcting apparatus according to any one of the first to third aspects, further comprising a driving unit for moving the pressing force adjusting unit. Things.
[0012]
According to this configuration, the holding section has a constant width in the moving direction of the pressing force adjusting means, and the control of the pressing force adjusting means by the driving means is sufficient with the stepwise control of the driving amount. No precision is required for control.
[0013]
According to a fifth aspect of the present invention, there is provided the sheet curling device according to any one of the first to fourth aspects, in order to correct the curl generated on the transfer sheet on which the toner image is formed. An image forming apparatus characterized in that:
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a paper curl correcting apparatus and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a color printer which is an example of an image forming apparatus according to the present invention.
[0015]
A schematic configuration of a color printer 1 to which the present invention is applied will be described with reference to FIG. The color printer 1 forms a paper feed unit 4 for feeding the transfer paper 3 one by one, a transport unit 6 for transporting the transfer paper 3 sent from the paper feed unit 4, and forms a toner image to be transferred onto the transfer paper 3. An image forming unit 5, a transfer unit 7 for transferring the toner image formed by the image forming unit 5 to the transfer sheet 3, a fixing unit 8 for fixing the toner image of the transfer sheet 3 transferred by the transfer unit 7, The image forming apparatus includes a paper discharge unit 10 that receives the transfer paper 3 discharged from the fixing unit 8 and an exposure unit 11 that forms an electrostatic latent image on the photosensitive drum 28 by a laser beam.
[0016]
The paper feed unit 4 includes a first paper feed unit 15 that feeds the transfer paper 3 stacked on the first paper feed tray 12 to the downstream side one by one with a paper feed roller 13 and a retard roller 14, and a manual feed tray 16. A second paper feed unit 18 that feeds the transfer paper 3 downstream by a paper feed roller 17 one by one.
[0017]
The transport unit 6 includes a transport path 20 that guides the transport of the transfer paper 3 sent from the first paper supply unit 15, a transport roller 21 disposed in the middle of the transport path 20, and a transfer sheet from the transport roller 21. 3 and a pair of registration rollers 22 for temporarily stopping the leading end of the transfer sheet 3 to regulate (correct) the oblique feed and feed the image to the image forming section 5 on the downstream side, and a manual feed path 23 leading to the second sheet feeding section 18. It is composed of
[0018]
The image forming unit 5 includes a first image forming unit 24 having black toner, a second image forming unit 25 having cyan toner, a third image forming unit 26 having magenta toner, and a fourth image forming unit 27 having yellow toner. It is composed of The first to fourth image forming units 24, 25, 26, and 27 include a cylindrical photosensitive drum 28 and a charging unit that applies a charge to the photosensitive drum 28 to uniformly charge the surface of the photosensitive drum 28. 29, a developing unit 30 for forming a toner image on the surface of the photosensitive drum 28, and a cleaning device 33 including a fur brush 31 and a cleaning blade 32 for removing residual toner on the photosensitive drum 28. I have.
[0019]
The transfer unit 7 includes an endless transfer belt 37 made of a fluorine-based resin material, a driving roller 38 and a tension roller 40 for driving the transfer belt 37, and transfer rollers 41a arranged at positions facing the respective photosensitive drums 28. , 41b, 41c, and 41d, and has a function of transferring the transfer sheet 3 to the downstream side in addition to a function of transferring the image to the transfer sheet 3. The transfer belt 37 is held between the transfer rollers 41a, 41b, 41c, and 41d and the photosensitive drums 28. Guide rollers 42 and 43 are provided at appropriate positions on the inner peripheral side of the transfer belt 37. When forming only a black-and-white image, the transfer unit 7 uses only the black transfer roller 41a, and the other magenta, cyan, and yellow transfer rollers 41b, 41c, and 41d are separated from the photosensitive drum 28. .
[0020]
The fixing unit 8 includes a heating roller 44 having a built-in heater, a fixing roller 45, a metal endless belt 46 wound around the heating roller 44 and the fixing roller 45, and a pressure applied to the fixing roller 45. And a roller 47. An oil application roller 48 that applies silicon oil to the outer surface of the endless belt 46, an oil supply roller 50 that supplies oil to the oil application roller 48, and a cleaning roller 51 that cleans the surface of the oil supply roller 50 are provided. Have been.
[0021]
A paper curl correcting device 70 having a driving roller and a pressure roller is provided in the paper discharge path 53 on the downstream side of the fixing unit 8. The paper curl correcting device 70 is a feature of the present invention, and is provided to correct curl generated on the transfer paper 3 under the influence of heat and pressure when the paper passes through the fixing unit 8.
[0022]
The paper discharging unit 10 receives the transfer paper 3 discharged from the fixing unit 8 and discharges the image forming surface upward with a first paper discharging unit 52 (illustrated by a virtual line in FIG. 1) and the fixing unit 8. The transfer paper 3 that has been discharged is guided to the upper portion of the apparatus main body 36 by a discharge path 53, and has a second discharge portion 54 that is discharged with the image forming surface down. Note that the first paper discharge unit 52 is stored in the apparatus main body 36 when not in use.
[0023]
The exposure unit 11 has a polygon mirror 55, lenses 56, 57 and a mirror 58 disposed corresponding to each of the photosensitive drums 28, and emits laser light from slits 61 formed in the exposure unit support plate 60. Irradiation is performed on the photosensitive drum 28.
[0024]
In the color printer 1 having the above-described configuration, when the transfer paper 3 is sent out from the first paper supply unit 15 or the second paper supply unit 18, the transfer paper 3 is transferred to the photosensitive member of the first image forming unit 24 by the transport unit 6. It is fed between the drum 28 and the transfer belt 37. Then, the transfer paper 3 is successively conveyed between the photosensitive drum 28 of each color and the corresponding transfer roller 41a, 41b, 41c, 41d, and the toner image is formed on the photosensitive drum 28 of black, cyan, magenta, and yellow. The images are sequentially transferred to the transfer sheet 3. The transfer paper 3 on which the toner images of the respective colors are superimposed and the transfer of the color image is completed is sent between the fixing roller 45 and the pressure roller 47 of the fixing unit 8, where the color image is fixed. After the fixing, the transfer paper 3 is discharged to the first paper discharge unit 52 or the second paper discharge unit 54.
[0025]
The paper curl correcting device 70 will be described. FIG. 2 is a perspective view showing the paper curl correcting device 70, FIG. 3A is a side view showing the paper curl correcting device 70, and FIG. 2B is a difference in the distance between the driving roller and the pressure roller in each holding portion. FIG. The paper curl correction device 70 includes a drive roller 71 that is driven to rotate by a drive motor (not shown), a pressure roller 72 that is pressed against the drive roller 71, and a pressing force adjustment plate that sandwiches the rotation shafts of the rollers 71 and 72. (Pressing force adjusting means) 73.
[0026]
The drive roller 71 is rotatably supported by a device housing (not shown), and is fixedly mounted on the shaft. A hard roller surface made of iron or the like is provided around the rotation shaft 71 a of the drive roller 71, and this roller surface comes into contact with the transfer paper 3. The pressure roller 72 has a sponge roller 74 mounted around a rotation shaft 72a, and the sponge roller 74 is pressed into contact with the drive roller 71 so as to bite, and the rotation shaft is rotatably mounted on the device housing. I have. As a result, the pressure roller 72 rotates following the drive roller 71 and is urged away from the drive roller 71. As shown in FIG. 3, the pressure roller 72 is slidable in a direction in which the rotation shaft 72 a approaches and separates from the drive roller 71 so that the distance between the rotation shaft and the drive roller 71 can be changed. It is mounted in a slot 19 formed in the device housing.
[0027]
By passing the transfer sheet 3 through the nip between the drive roller 71 and the pressure roller 72, tension is applied to the transfer sheet 3 by the pressing force of the pressure roller 72 (sponge roller 74) against the drive roller 71, and the transfer sheet 3 is transferred. The transfer sheet 3 is curved along the hard drive roller 71 to correct the curl.
[0028]
The rotating shaft 71a of the driving roller 71 and the rotating shaft 72a of the pressure roller 72 are provided with bearings 75 and 76 at both ends in the axial direction. The bearings 75 and 76 are provided with depressions in the outer peripheral portion, and are held by the pressing force adjusting plate 73 in a state where the opening 77 of the pressing force adjusting plate 73 is fitted in the recessed portion.
[0029]
The opening 77 of the pressing force adjusting plate 73 sandwiches both rotating shafts 71 a, 72 a via bearings 75, 76 of the driving roller 71 and the pressure roller 72 at the inner peripheral portion thereof, and pushes the pressure roller 72 against the driving roller 71. The pressure is kept constant.
[0030]
As shown in FIG. 3A, the inner peripheral portion of the opening 77, which is in contact with the bearing 76 of the pressure roller 72, is divided into three regions by providing a step. The bearings 75 and 76 of the drive roller 71 and the pressure roller 72 are sandwiched between these regions and the inner peripheral portion of the opening 77 and the portion in contact with the bearing 75 of the drive roller 71. A first holding portion 77a, a second holding portion 77b, and a third holding portion 77c are provided for each of the above regions.
[0031]
As shown in FIG. 3B, when the distance from the portion of the second holding portion 77b in contact with the bearing 76 to the center of the rotating shaft 71a of the driving roller 71 is set to the reference value A, the first holding portion 77a is adjusted. The distance AB that is shorter by the value B and the third holding portion 77c are formed so as to be the distance A + B that is longer by the adjustment value B, and the first holding portion 77a, the second holding portion 77b, and the third holding portion 77c. The distance between the rotating shaft 71a of the driving roller 71 and the rotating shaft 72a of the pressure roller 72 is changed stepwise so as to sandwich the rollers 71, 72. The holding portion 77a, 77b, 77c has a constant width in the moving direction of the pressing force adjusting plate 73 in a region where the distance from the portion where each holding portion is in contact with the bearing 76 to the center of the rotating shaft 71a of the drive roller 71 is constant. Therefore, the driving roller 71 and the pressure roller 72 are held by the same pressing force in each holding portion.
[0032]
The opening 77 has a shape of a portion of the drive roller 71 that contacts the bearing 75 at an angle of about 90 degrees, and the pressing force adjusting plate 73 can be rotated by about 90 degrees in the direction of the arrow in FIG. . When the pressing force adjusting plate 73 rotates, the inner peripheral side portion 79 of the opening 77 comes into contact with the bearing 76 to stop the rotation.
[0033]
Further, the pressing force adjusting plate 73 is provided with holes 73a and 73b for screwing, and the pressing force adjusting plate 73 contacts the bearing 76 of the pressure roller 72 with a holding portion for obtaining a desired pressing force. In this state, it can be fixed to the device housing.
[0034]
Next, a driving mechanism of the pressing force adjusting plate 73 will be described. 4 to 6 are views showing examples in which a driving mechanism is provided on the pressing force adjusting plate 73. FIG. In the embodiment described above, the pressing force adjusting plate 73 is manually rotated. However, when the pressing force adjusting plate 73 is rotated by the driving mechanism, the following configuration is adopted.
[0035]
As shown in FIG. 4, gear teeth 80a are provided on the outer peripheral portion of the pressing force adjusting plate 73 and mesh with a gear 80b attached to a driving motor (not shown), and the pressing force is adjusted by the driving force from the driving motor. The plate 73 is configured to rotate in the direction of the arrow in FIG.
[0036]
Further, as shown in FIG. 5, a rack 81 for loosely fitting and engaging with the projection 73c of the pressing force adjusting plate 73 is attached, and gear teeth 81a provided on the rack 81 are not shown. As a configuration that meshes with the gear 82 attached to the drive motor, a configuration in which the pressing force adjusting plate 73 is rotated in the direction of the arrow in FIG. 5 may be employed.
[0037]
As shown in FIG. 6, a gear 83a is fixed to the pressing force adjusting plate 73 so as not to hinder the rotation of the driving roller 71, and the gear 83a and a gear 83b attached to a driving motor (not shown). Alternatively, a configuration may be adopted in which a toothed rubber belt 84 whose inner peripheral portion has a shape corresponding to these gear teeth is stretched, and the pressing force adjusting plate 73 is rotated by a driving force from a driving motor. The pressing force adjusting plate 73 shown in FIGS. 4 to 6 is configured to rotate around a rotation shaft 71 a of the driving roller 71.
[0038]
With the configuration in which the pressing force adjusting plate 73 is rotated by the driving mechanism in this manner, since the holding portions 77a, 77b, and 77c have a certain width in the moving direction of the pressing force adjusting plate 73, the pressing mechanism is driven by the driving mechanism. Since the rotational drive of the pressure adjusting plate 73 can be controlled by stepwise control of the drive amount, a high-precision motor is not required for the drive source.
[0039]
As described above, according to the paper curl correcting device 70 of the present embodiment, since the driving roller 71 and the pressure roller 72 are nipped by the opening 77 of the pressing force adjusting plate 73, the pressing force between the rollers 71, 72 is kept constant. Can be maintained stably. In addition, since each of the holding portions 77a, 77b, and 77c has a constant width in the moving direction of the pressing force adjusting plate 73, the operation for obtaining a desired pressing force does not require accuracy. Moreover, since the pressing force can be adjusted by the simple structure of sandwiching the rollers 71 and 72 between the opening portions 77 of the pressing force adjusting plate 73 as described above, the pressing force adjusting plate 73 (the paper curl correcting device 70) can be used. ) Can be manufactured at low cost. Further, since the holding portions 77a, 77b, 77c hold the bearings 75, 76 of the rollers 71, 72, the resistance when the pressing force adjusting plate 73 rotates is small.
[0040]
Note that the present invention is not limited to the configuration of the above embodiment, and various modifications are possible. 7 to 10 are views showing modified examples of the pressing force adjusting plate 73. For example, as shown in FIG. 7, the pressing force adjusting plate 85 is configured to rotatably support a bearing 75 of the driving roller 71 and rotate around a rotation shaft 71 a of the driving roller 71. As a substantially semicircular shape, the pressing force adjusting plate 85 may be rotated about 180 degrees. In this case, more steps can be provided in the opening 87 than the pressing force adjusting plate 73 described above, and the pressing force can be adjusted in more steps.
[0041]
Further, both the rotation shafts 71a and 72a of the drive roller 71 and the pressure roller 72 are configured to be slidable, and the opening 88 of the pressing force adjusting plate 87 is connected to the bearing 75 of the drive roller 71 as shown in FIG. It has a shape having a plurality of holding portions 88a, 88b, 88c at the contacting portion, and the pressing force between the two rollers 71, 72 is adjusted by moving the rotating shafts 71a, 72a of both the driving roller 71 and the pressure roller 72. You may make it so.
[0042]
Similarly, the rotating shafts 71a, 72a of both the driving roller 71 and the pressure roller 72 are configured to be linearly slidable, and the pressing force adjusting plate 89 is formed in the shape shown in FIG. The two rollers 71 and 72 may be moved relative to each other to adjust the pressing force between the rollers 71 and 72.
[0043]
In the above embodiment, the pressing force adjusting means has a plate shape, but the pressing force adjusting means is not limited to a plate-shaped member, and may be a member having another shape.
[0044]
As shown in FIG. 10, the opening 101 of the pressing force adjusting plate 100 is formed in a substantially circular shape, and a plurality of steps are provided in an inner peripheral portion thereof, and the support extends from the adjusting plate main body 100 a toward the substantially center of the opening 101. The bearing 75 of the drive roller 71 may be rotatably supported by the member 100b, and the pressing force adjustment plate 100 may be configured to rotate around the rotation shaft 71a of the drive roller 71. In this configuration, the support member 100 b is provided so as not to interfere with the rotation of the pressure roller 72, so as not to contact the bearing 76 of the pressure roller 72, and the sponge roller 74 of the pressure roller 72 is formed inside the opening 101. It is set so as to be pressed against the drive roller 71 regardless of the level difference of the peripheral portion (however, the pressing force applied to the drive roller 71 depends on the level difference held). In this case, more steps can be provided in the opening 101 than the pressing force adjusting plates 73 and 85 described above, and the pressing force can be adjusted in more steps.
[0045]
Further, in the above-described embodiment, the case where the paper curl device 70 is applied to the transfer paper 3 after passing through the fixing unit 8 is described, but the invention is not limited to this.
[0046]
Further, in the above-described embodiment, an example in which the paper curl correcting device 70 is applied to the color printer 1 is described. However, the paper curl correcting device 70 may be an electrophotographic color copier or a facsimile regardless of color or monochrome. The present invention can be applied to an image forming apparatus other than the electrophotographic type (eg, an ink jet type image forming apparatus).
[0047]
【The invention's effect】
As described above, according to the present invention, the pressing force between the two rollers is adjusted by sandwiching the rotation shafts of the two rollers in the opening of the pressing force adjusting means, so that a constant pressing force can be stably maintained. Further, since the holding portion for holding the rotating shafts of the two rollers has a constant width in the moving direction of the pressing force adjusting means, the operation for obtaining the desired pressing force does not need to be precise. In addition, since a simple structure in which the rotation shafts of both rollers are sandwiched between the openings of the pressing force adjusting means is sufficient, the device can be manufactured at low cost.
[0048]
Further, when the pressure adjusting means is configured to be rotatable, the pressing force adjusting means can be smoothly moved with respect to the rotation axis of the roller, and the structure which enables the pressing force adjusting means to move is compact. Can be configured.
[0049]
In addition, when the rotation axis position of the driving roller is fixed and the rotation axis of the pressure roller is movable in the direction of contacting and separating from the driving roller, the rotation axis position on the driving roller side to which the rotation driving force is transmitted is fixed. In addition, the reliability of the apparatus is high, and the pressing force adjusting means can be stably rotated around the rotation axis of the fixed drive roller as the center of rotation.
[0050]
When the driving means for rotating the pressing force adjusting means is further provided, the holding portion has a constant width in the moving direction of the pressing force adjusting means, and the control of the pressing force adjusting means by the driving means is stepwise. Since a simple control of the driving amount is sufficient, a high-precision driving source is not required.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a color printer as an example of an image forming apparatus according to the present invention.
FIG. 2 is a perspective view showing a sheet curl correcting device according to the present invention.
FIG. 3A is a side view illustrating the paper curl correcting device, and FIG. 3B is a diagram illustrating a difference in a distance between a driving roller and a pressure roller in each holding section.
FIG. 4 is a diagram showing an example in which a driving mechanism is provided on a pressing force adjusting plate.
FIG. 5 is a diagram illustrating an example in which a driving mechanism is provided on a pressing force adjusting plate.
FIG. 6 is a diagram showing an example in which a driving mechanism is provided on a pressing force adjusting plate.
FIG. 7 is a view showing a modification of the pressing force adjusting plate.
FIG. 8 is a view showing a modification of the pressing force adjusting plate.
FIG. 9 is a view showing a modification of the pressing force adjusting plate.
FIG. 10 is a view showing a modification of the pressing force adjusting plate.
FIGS. 11A and 11B are diagrams showing a schematic configuration of a conventional paper curl correcting apparatus.
[Explanation of symbols]
1 color printer (image forming device)
3 Transfer paper 70 Paper curl correcting device 71a Rotary shaft 72 Pressure roller 72a Rotary shafts 73, 85, 87, 89 Pressing force adjusting plate 73c Projecting portion 77 Opening portion 77a First holding portion 77b Second holding portion 77c Third holding portion 80a Gear teeth 80b Gear 81 Rack 81a Gear teeth 82 Gear 83a Gear 83b Gear 84 Belt

Claims (5)

A paper curl correction device that has a drive roller and a pressure roller whose distance between the rotation axes is changeable, and corrects the curl of the transfer sheet by passing the transfer sheet through the nip portion of both rollers.
In a state in which the distance between the rotation axes of the two rollers is kept constant, an opening provided with a plurality of holding parts capable of holding the rotation axes of the two rollers is provided, and a holding part for holding the rotation axes of the two rollers is provided. Having a pressing force adjusting means movably configured to change,
The paper curling device according to claim 1, wherein the holding portion has a constant width in a moving direction of the pressing force adjusting means. 2. The paper curl correcting device according to claim 1, wherein the pressing force adjusting unit is configured to be rotatable, and the holding unit that holds the rotation shafts of the two rollers is changed by the rotation. The paper according to claim 1, wherein the driving roller has a fixed rotation axis position, and the pressure roller has a rotation axis movable in a direction of contacting and separating from the driving roller. 4. Curling straightener. 4. The sheet curling device according to claim 1, further comprising a driving unit for moving the pressing force adjusting unit. 5. An image forming apparatus comprising: the sheet curl correcting device according to claim 1 for correcting curl generated on transfer paper on which a toner image is formed.

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