JP2013067456A - Conveying apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the deflection of a paper sheet by a highly accurate, low-cost, simple configuration.SOLUTION: The conveying apparatus 500 includes: deflection detection sensors 85 and 86 to measure the deflection amount of the paper sheet P; steering rollers 80 and 81; and a loop formation sensor 92 to detect the paper sheet P conveyed by the steering rollers 80 and 81. When the fed paper sheet P is detected by the loop formation sensor 92, the steering rollers 80 and 81 are suspended or reversely rotated, then, the tip of the paper sheet P is abutted on the steering rollers 80 and 81 to form the loop, and then, the drastic deflection of the paper sheet P is corrected (abutting deflection correction). Thereafter, when the conveyance of the paper sheet P is restarted, the deflection amount of the paper sheet P is measured by the deflection detection sensors 85 and 86, and the steering rollers 80 and 81 are independently driven on the basis of the measured deflection amount to perform the final deflection correction of the paper sheet P (steering deflection correction).

Description

  The present invention relates to a conveyance device and an image forming apparatus that correct paper skew.

  In recent years, multifunctional image forming apparatuses having functions such as printers, scanners, copiers, and fax machines have been widely used. In the image forming apparatus, the sheet may be skewed during conveyance of the sheet due to mechanical factors of the apparatus. In such a case, since the image formation position is shifted and the image is printed on the paper, conventionally, paper skew correction for correcting the paper skew (skew) of the paper during paper transport has been performed.

  To correct the paper skew, the paper tip is abutted against the nip of the roller pair that is stopped and reversely rotated to form a loop, and the paper tip is aligned with the roller nip by the elasticity of the paper. There is a correction. As another correction method, the rollers are arranged on the same axis in the direction orthogonal to the paper passing direction at a predetermined interval, and the rollers are bent at a predetermined interval on the same axis in the vicinity of these rollers. There is a steering bend correction in which a detection sensor is arranged and each roller is driven independently according to the amount of bend caused by the time difference of the leading end of the sheet detected by each bend detection sensor, thereby correcting the bend of the sheet.

  However, although the above-described abrupt bend correction is effective for a bend correction from a relatively large sheet bend to a small bend, there is a problem that it is difficult to adjust the bend amount. In order to cope with such correction, it is necessary to vary the inclination of the registration roller against which the front end of the paper is abutted according to the adjustment of the bending amount. However, it is very difficult to design the apparatus, and the apparatus is also large. Will become costly. Further, in the case of front and back printing, since the time for switching between the front and back surfaces is short, there is also a problem that there is no time margin for changing the amount of bending of the registration rollers.

  On the other hand, the steering bend correction can cope with the adjustment of the bend amount, but when performing a large bend correction at a time, it must be rotated at a large speed difference according to the bend amount between a pair of rollers. There is a problem that the amount of bending is deviated when errors accumulate or when the uniformity of the conveying force of the independently driven conveying roller is deviated due to durability.

  In order to solve this problem, use multiple bending detection sensors to correct large paper bending using the first bending detection sensor, and then correct the bending of paper that could not be removed by this correction. There has been proposed a method for correcting the skew of a sheet detected by a detection sensor. For example, in Patent Documents 1 and 2, a first sheet skew detection unit and a second sheet skew detection unit are disposed downstream of the first sheet skew detection unit, and the first and second sheet skew detection units are arranged in two stages. A sheet conveying apparatus that corrects the bending is disclosed. According to these sheet conveying apparatuses, it becomes possible to skew the sheet with high accuracy.

Japanese Patent No. 3233758 JP 2010-24053 A

  However, the skew correction of the sheet by the sheet conveying device disclosed in Patent Documents 1 and 2 has the following problems. That is, in the sheet conveying apparatus, at least two stages of a pair of paper bending detection sensors must be arranged, and there is a problem that the cost increases due to design restrictions and an increase in sensors due to the use of many sensors. is there.

  SUMMARY An advantage of some aspects of the invention is that it provides a conveyance device and an image forming apparatus capable of correcting the skew of a sheet with high accuracy, low cost, and a simple configuration. There is.

  In order to solve the above problems, a transport device according to the present invention includes a plurality of first detection sensors that are arranged at a predetermined interval in a direction orthogonal to the sheet passing direction and that measure the amount of bending of the transported paper. A plurality of first roller members provided on the upstream side of the first detection sensor and arranged at a predetermined interval in a direction orthogonal to the paper passing direction, and provided on the upstream side of the first roller member, A second detection sensor for detecting the paper conveyed to the first roller member, and the bending of the paper by independently driving the first roller member based on the bending amount of the paper measured by the first detection sensor. And a control unit that performs a first correction operation for correcting the first roller member based on a detection result of the sheet by the second detection sensor before performing the first correction operation. Stop rotation or reverse rotation, and make the leading edge of the paper the first roller Abutted against the wood and performs second correction operation for correcting the bending of a sheet by forming a loop.

  In the present invention, after the transported paper passes through the second detection sensor, the paper hits the first roller member whose rotation is stopped or reversed. After the paper has passed through the second detection sensor, the paper conveyance is stopped in a certain time, and the paper leading edge follows the first roller member due to the paper rigidity due to the paper loop formation. Bending correction is performed.

  When the second correction operation is performed, the driving is resumed by the first roller member rotating forward. As a result, the amount of bending of the sheet based on the time difference of the leading edge of the sheet that has passed through the first roller member is measured by the first detection sensor, and based on the amount of bending measured by the first detection sensor, a plurality of bending amounts are measured. By driving the first roller members independently, a first correction operation for correcting the final bending of the sheet is performed. For example, in the first correction operation, the correction of the paper bending and the adjustment of the bending amount that cannot be removed in the second correction operation are performed. The adjustment of the bending amount includes, for example, bending adjustment in the case where the leading end side of the sheet is set obliquely in a normal reference state.

  In the present invention, the first detection sensor is composed of a plurality of sensors that detect the bending of the sheet, and the second detection sensor is composed of a loop creation sensor that detects the sheet conveyed to the first roller member. The

  According to the present invention, first, in the second correction operation, a large skew correction of the paper is performed by abutting the leading edge of the paper against the first roller member, and subsequently, based on the detection result of the first detection sensor. Correction that finely adjusts the bending of the sheet can be performed by driving the first roller members independently of each other. Thereby, with a simple configuration, it is possible to cope with a large amount of bending of the paper and to adjust the amount of bending of the paper.

1 is a diagram illustrating a configuration example of an image forming apparatus according to a first embodiment of the present invention. (A) is a side view which shows the structural example of a conveying apparatus, (B) is the top view (the 1). (A) is a side view which shows the structural example of a conveying apparatus, (B) is the top view (the 2). It is a figure which shows the structural example of a press-contact force variable mechanism part. (A)-(C) are figures which show the operation example of a press-contact force variable mechanism part. It is a figure for demonstrating the press-contact force by a press-contact force variable mechanism part. 1 is a diagram illustrating a block configuration example of an image forming apparatus. 6 is a timing chart illustrating an operation example of the image forming apparatus at the time of collision correction and steering correction. 5 is a flowchart illustrating an operation example of the image forming apparatus when abutting bend correction and steering bend correction are performed. It is a figure which shows the structural example of the press-contact force variable mechanism part in the conveying apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of a press-contact force variable mechanism part.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
<1. First Embodiment>
[Configuration example of image forming apparatus]
The image forming apparatus 100 according to the first embodiment of the present invention first performs an abrupt bend correction (second correction operation) for correcting a large bend on the paper P conveyed from the paper supply unit 20. Next, the skew of the paper P is corrected by performing the steering curve correction (first correction operation) for adjusting the curve amount. That is, before performing the steering curve correction that has been conventionally performed, the paper curve is corrected with high accuracy by performing the steering curve correction once.

  The abutting and bending correction is based on stopping or reversely rotating the steering rollers 80 and 81 based on the detection result of the paper P of the loop creation sensor 92, and stopping the loop creation rollers 90 and 91 after elapse of a predetermined time. In this operation, the leading edge of the paper P is abutted against the steering rollers 80 and 81 to form a loop, and the rigidity of the paper P is used to correct a large bending of the paper P. Steering bend correction operation refers to a steering roller in which the steering rollers 80 and 81 of different driving sources are independently driven to rotate based on the amount of bend according to the time difference of the paper P measured by the paper bend detection sensors 85 and 86. This is an operation for correcting the final bending of the paper P by the difference between the linear speeds of 80 and 81.

  As shown in FIG. 1, the image forming apparatus 100 is called a tandem type image forming apparatus, and includes an automatic document feeder 101 and an apparatus main body 102. The automatic document conveyance unit 101 is attached to the upper part of the apparatus main body unit 102 and sends out the paper M set on the conveyance table to the image reading unit 110 of the apparatus main body unit 102 by conveyance rollers or the like.

  The apparatus main body 102 includes an image reading unit 110, an image forming unit 60, an intermediate transfer belt 8, a conveying device 500, and a fixing device 72. The image reading unit 110 scans and exposes a document placed on a document table by an optical system of a scanning dew apparatus, and photoelectrically converts an image of the document scanned by a CCD image sensor to generate an image information signal. The image information signal is output to the image forming unit 60 after being subjected to analog processing, analog / digital (hereinafter referred to as A / D) conversion processing, pseudo correction, image compression processing, and the like by an image processing unit (not shown).

  The image forming unit 60 forms an image by an electrophotographic method. The image forming unit 10Y forms a yellow (Y) image, the image forming unit 10M forms a magenta (M) image, The image forming unit 10C forms a cyan (C) color image, and the image forming unit 10K forms a black (K) color image. In this example, common function names, for example, Y, M, C, and K indicating colors to be formed are added to the back of the reference numeral 10.

  The image forming unit 10Y includes a photosensitive drum 1Y, a charging unit 2Y, an exposure unit (optical writing unit) 3Y, a developing unit 4Y, and a cleaning unit 6Y disposed around the photosensitive drum 1Y. The image forming unit 10M includes a photosensitive drum 1M, and a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 6M disposed around the photosensitive drum 1M. The image forming unit 10C includes a photosensitive drum 1C, and a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 6C arranged around the photosensitive drum 1C. The image forming unit 10K includes a photosensitive drum 1K, and a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a cleaning unit 6K disposed around the photosensitive drum 1K.

  Respective photosensitive drums (image carriers) 1Y, 1M, 1C, and 1K in the image forming units 10Y, 10M, 10C, and 10K, charging units 2Y, 2M, 2C, and 2K, exposure units 3Y, 3M, 3C, and 3K, development The parts 4Y, 4M, 4C, and 4K and the cleaning parts 6Y, 6M, 6C, and 6K have a common content configuration. In the following description, Y, M, C, and K are not used unless particularly distinguished.

  The charging unit 2 charges the surface of the photosensitive drum 1 almost uniformly. The exposure unit 3 is constituted by, for example, a polygon mirror type laser exposure scanning device, and forms an electrostatic latent image by scanning the photosensitive drum 1 with a laser beam based on an image information signal. The developing unit 4 develops the electrostatic latent image formed on the photosensitive drum 1 with toner. As a result, a toner image which is a visible image is formed on the photosensitive drum 1. The intermediate transfer belt 8 is stretched by a plurality of rollers and supported so as to be able to run. When the primary transfer roller operates, the intermediate transfer belt 8 travels, and the toner image formed on each photosensitive drum 1 is transferred to the image transfer position of the intermediate transfer belt 8 (primary transfer).

  The paper feed unit 20 includes a plurality of paper feed trays 20A, 20B, and 20C that accommodate paper sizes such as A3 and A4. The paper P transported from the paper feed trays 20A, 20B, and 20C by the transport rollers 21, 22 and the like is transported to the steering rollers 80 and 81 via the loop creation rollers 90 and 91 that constitute the transport device 500. In the steering rollers 80 and 81, when the paper P is detected by the loop creation sensor 92, the leading end of the paper P is abutted to form a loop, thereby correcting a large bend of the paper P (abutting bend correction). Operation). Subsequently, when the abutting and bending correction operation is completed, the paper P is conveyed, and the bending detection sensors 85 and 86 further detect the remaining bending amount of the paper P. In the steering rollers 80 and 81, the steering rollers 80 and 81, which are separate driving sources, are independently driven based on the detection results of the bending detection sensors 85 and 86, so that the final bending of the sheet P is caused by the linear speed difference between the rollers. Is corrected (steering curve correction operation).

  When the steering bend correction operation is completed, the paper P is conveyed to the shift roller 30 on the downstream side in the paper passing direction. The shift roller 30 corrects the deviation of the sheet P by shifting the sheet P in the direction D2 orthogonal to the sheet passing direction based on the detection result of the line sensor 70 (shift correction operation), and then at a predetermined timing. It is conveyed to the secondary transfer unit 36. In the secondary transfer unit 36, the color image transferred to the image forming position of the intermediate transfer belt 8 is collectively transferred onto the surface of the paper P conveyed from the paper supply unit 20 (secondary transfer). The sheet P that has been secondarily transferred is conveyed to the fixing device 72.

  The fixing device 72 fixes the color image on the paper P by heating and pressurizing the paper P on which the color image is transferred. The paper P fixed by the fixing device 72 is discharged onto the paper discharge tray 25 via the paper discharge roller 24.

  The image forming apparatus 100 also includes a paper reversing unit 27 for performing double-sided printing or the like. When the duplex printing mode is set, the paper P fixed by the fixing device 72 is guided to the paper reversing unit 27, reversed front and back, and conveyed again to the secondary transfer unit 36, and the back side of the paper P A color image or the like is formed.

[Configuration example of transport device]
2A and 3A are side cross-sectional views of the transport device 500 as viewed from the orthogonal direction D2, and FIGS. 2B and 3B are plan views thereof. As shown in FIGS. 2 and 3, the conveying device 500 includes a pair of loop creation rollers 90 and 91, a loop creation motor 93, a loop creation sensor 92, a pair of steering rollers 80 and 81, a steering drive motor 83 and 84, and a pair. Bending detection sensors 85 and 86, a shift roller 30, and a line sensor 70.

  The loop creation sensor 92 is composed of, for example, transmission type sensors 92A and 92B, and is installed upstream of the steering rollers 80 and 81 and in the vicinity of the center reference C. The loop creation sensor 92 detects the leading edge of the conveyed paper P at a stage before the paper P reaches the steering rollers 80 and 81. The loop creation sensor 92 constitutes an example of a second detection sensor.

  The loop creation rollers 90 and 91 are arranged at a predetermined interval in an orthogonal direction orthogonal to the paper passing direction, and are installed upstream of the loop creating sensor 92 in the paper passing direction. The loop creation rollers 90 and 91 correct the skew of the paper P by forming a loop by abutting the leading ends of the paper P against the steering rollers 80 and 81 during the abutting and bending correction operation (FIG. 3A). Dotted line). The loop creating roller 90 has a driving roller 90A connected to the loop creating motor 93 and a driven roller 90B. Similarly, the loop creating roller 91 has a driving roller 91A connected to the loop creating motor 93 and a driven roller 91B. The loop creation rollers 90 and 91 constitute an example of a second roller member.

  The loop creation motor 93 is composed of, for example, a stepping motor or the like, and is connected to the drive rollers 90A and 91A of the loop creation rollers 90 and 91 via the rotation shaft O3. The loop creation motor 93 stops the loop creation rollers 90 and 91 after a predetermined time Ta has elapsed from the detection of the loop creation sensor 92 (see FIG. 8) during the abutting and bending correction operation, and a predetermined conveyance speed during the steering bending correction operation. The loop creation rollers 90 and 91 are rotated at.

  The steering rollers 80 and 81 are rollers that are used at the time of the correction of the abutting bend and the correction of the steering bend, and are arranged at a predetermined interval in the width direction of the paper P with the center reference C of the transport path of the paper P being symmetrical. Yes. The spacing between the steering rollers 80 and 81 is selected so that various sizes of paper P used in the image forming apparatus 100 can be conveyed. Further, as shown in FIGS. 2A and 3A, the steering roller 80 has a driving roller 80A and a driven roller 80B. The driven roller 80B is pressed against or released from the driving roller 80A by a pressing force variable mechanism 300 described later. The steering roller 81 has the same configuration as the steering roller 80. The steering rollers 80 and 81 constitute an example of a first roller member.

  The steering drive motor 83 is composed of, for example, a stepping motor or the like, and is connected to the drive roller 80A of the steering roller 80 via the rotation shaft O1. The steering drive motor 83 stops or reversely rotates the steering roller 80 during the abutting and bending correction operation to stop the paper P, and conveys the paper P by rotating the steering roller 80 forward during the steering bending correction operation.

  Similarly, the steering drive motor 84 is composed of, for example, a stepping motor or the like, and is connected to the drive roller 81A of the steering roller 81 via the rotation shaft O2. The steering drive motor 84 stops or reversely rotates the steering roller 81 during the abutting and bending correction operation to stop the paper P, and conveys the paper P by rotating the steering roller 81 forward during the steering bending correction operation. Therefore, the steering rollers 80 and 81 are rotationally driven independently by steering drive motors 83 and 84 which are separate drive sources.

  The bending detection sensors 85 and 86 are downstream of the steering rollers 80 and 81 in the sheet passing direction, and have a predetermined interval in the orthogonal direction D2 perpendicular to the sheet passing direction D1 with the center reference C symmetrical. Are arranged apart from each other. In this example, the bending detection sensors 85 and 86 are arranged at substantially the same intervals as the steering rollers 80 and 81. Further, as shown in FIGS. 2 (A) and 3 (A), the bending detection sensor 85 includes a pair of transmission sensors 85A and 85B which are arranged to face the top and bottom of the transport path of the paper P. In the steering bend correction operation, the passage time of one leading edge of the paper P passing through the bend detection sensor 85 is detected. The bending detection sensor 86 has the same configuration as the bending detection sensor 85. The bending detection sensors 85 and 86 constitute an example of a first detection sensor.

  The shift roller 30 is installed downstream of the bending detection sensors 85 and 86 in the sheet passing direction, and the longitudinal direction of the roller is along the orthogonal direction D2 orthogonal to the sheet passing direction D1. As shown in FIGS. 2A and 3A, the shift roller 30 is composed of a drive roller 34 and a driven roller 32, and the driven roller 32 is pressed against the drive roller 34 by a shift roller pressing portion 44 described later. Or release this pressure contact. Accordingly, the shift roller 30 nips the paper P and moves in the orthogonal direction D2 orthogonal to the paper passing direction D1 of the paper P during the shift correction operation, thereby correcting the deviation of the paper P. The distance between the shift roller 30 and the bending detection sensors 85 and 86 is preferably set to a distance corresponding to approximately one turn of the steering rollers 80 and 81. This is to prevent the roller accuracy such as eccentricity of the steering rollers 80 and 81 from being greatly affected.

  The line sensor 70 includes a plurality of image sensors such as CCDs arranged in a line, and is arranged so that the arrangement direction thereof is along an orthogonal direction D2 orthogonal to the paper passing direction D1 of the paper P. Yes. Further, the line sensor 70 is installed on the downstream side of the shift roller 30 in the sheet passing direction D1 and overlaps at least one side edge of the paper P, and the side edge of the paper P that has passed through the shift roller 30. The position of is detected. The line sensor 70 constitutes an example of a third detection sensor.

[Configuration example of variable pressure welding mechanism]
FIG. 4 shows an example of the configuration of the pressing force variable mechanism unit 300. As shown in FIG. 4, the pressing force variable mechanism unit 300 includes a pressing force variable motor 302, a gear 304, and a leaf spring 310. The pressure contact force variable motor 302 is composed of a stepping motor, for example, and is driven to rotate based on a drive signal supplied from the control unit 50. The gear 304 is arranged so that the teeth on the peripheral surface mesh with a groove formed in the rotation shaft 302 a of the variable pressure contact force motor 302, and rotates forward or backward by driving the variable pressure contact force motor 302.

  The leaf spring 310 has a predetermined length, one end of which is fastened to the rotating shaft 304a of the gear 304 by a screw 306, and the other end is fastened to the rotating shaft O1 of the driven roller 80B by a screw 308. Accordingly, the leaf spring 310 is bent by the rotation of the gear 304 at one end of the leaf spring 310, and the driven roller 80B including the rotation shaft O1 is urged toward the driving roller 80A by the return force, so that the steering roller 80 is brought into the pressure contact state. Is done. In this example, the pressing force variable mechanism 300 of the steering roller 80 has been described. However, the steering roller 81 is also provided with the pressing force variable mechanism 300 having the same configuration.

[Operation example of variable pressure welding mechanism]
FIG. 5A to FIG. 5C show an example of the operation of the pressing force varying mechanism unit 300. At the time of shift correction, as shown in FIG. 5A, the steering roller 80 is adjusted by controlling the pressure contact force variable motor 302 so that the driving roller 80A and the driven roller 80B are separated to adjust the posture of the leaf spring 310. The nip is released. As a result, when the paper P is shifted in the orthogonal direction D2 by the shift roller 30, the paper P is not pinched by the steering roller 80, so that the deviation of the paper P is corrected without the paper P being pulled or wrinkled. Is done.

  In the case of the urging / curving correction operation, when the pressure contact force variable motor 302 is driven by the drive signal from the control unit 50, the gear 304 rotates counterclockwise accordingly. When the gear 304 rotates, the one end side of the leaf spring 310 fixed to the rotating shaft 304a of the gear 304 also rotates to bend the leaf spring 310, and the restoring force causes the other end side of the leaf spring 310 to be elastic in the rotation direction (downward). Moving. As a result, as shown in FIG. 5B, the driven roller 80B including the rotation shaft O1 fixed to the other end of the plate spring 310 is urged by the plate spring 310 toward the opposing drive roller 80A, and driven. The roller 80B moves in a direction approaching the driving roller 80A, and the driven roller 80B is brought into pressure contact with the driving roller 80A. When the pressing force variable motor 302 further rotates, the leaf spring 310 is bent and the rotating shaft O1 is urged by the return force. As a result, as shown in FIG. 5C, the pressure contact force by the driven roller 80B further increases, the pressure contact force changes from “medium” to “maximum”, and the paper P is reliably stopped without passing the paper P. Loops can be formed.

  In the case of the steering roller correction operation, the control unit 50 rotates the pressure contact force variable motor 302 in the reverse direction (clockwise), and no force is applied to the leaf spring 310 (deforms as shown in FIG. 5B). Not). As a result, the urging force of the leaf spring 310 against the rotation axis O1 of the driven roller 80B is slightly weakened, and the pressure contact force of the steering roller 80 is changed from “maximum” to “medium”. Thereby, the paper P can be conveyed with a predetermined frictional force.

[Example of pressing force of steering roller]
FIG. 6 is a diagram for explaining the pressure contact force of the steering rollers 80 and 81. FIG. 6 shows a case where the left end (lower side in FIG. 6) of the paper P is advanced further. As shown in FIG. 6, when the skew correction of the skewed paper P is performed, the paper P is rotated by using the linear velocity differences Va and Vb of the steering rollers 80 and 81, so that the steering rollers 80 and 81 are corrected. There is a speed difference between inside and outside. For example, at the inner side 80in and the outer side 80out of the steering roller 80, the speed of the inner side 80in is faster than the speed of the outer side 80out.

  As a method for avoiding the speed difference between the steering rollers 80 and 81, measures such as reducing the speed difference between the front and rear steering rollers 80 and 81 and reducing the width of the steering rollers 80 and 81 can be considered. However, if the speed difference between the steering rollers 80 and 81 is reduced, there is a problem that the amount of bending correction that can be dealt with decreases. When the roller width is reduced, the wear of the roller increases and the problem that the cycle of parts replacement increases.

  For the above reason, in the embodiment of the present invention, the speed difference at the time of large bending correction reduces the speed of the steering roller 80 by 15% with respect to the steering roller 81. More specifically, when the steering roller 81 is 500 mm / sec, the steering roller 80 is set to 425 mm / sec. The roller width is set to 20 mm. When the skew of the paper P is reversed, the speed settings of the steering rollers 80 and 81 are also reversed.

When the steering bend correction operation is performed under such conditions as speed difference, and the sheet P has a basis weight of about 40 g / m ² , the pressure contact force of each of the steering rollers 80 and 81 is It is preferable to set it to 10 N or less (the total of the pressure contact forces of the two rollers is 20 N) (corresponding to the pressure contact force “medium”). This is because if the paper weight exceeds 20 N, the thin paper with the basis weight of the paper P of about 40 g / m ² causes wrinkles in the paper P due to the speed difference. Therefore, the pressure contact force of the steering rollers 80 and 81 cannot be increased more than necessary at the time of correcting the steering curve.

On the other hand, when the abutting and bending correction operation is performed, when the paper P having a basis weight of about 200 g / m ² is used, the pressure contact force of each of the steering rollers 80 and 81 is 20 N (the sum of the pressure contact forces of the two rollers is 40N) is preferable (corresponding to the pressure contact force “maximum”). This is because, when there is no pressure contact force of about 20 N, when the paper P is abutted against the steering rollers 80 and 81, the steering rollers 80 and 81 are penetrated due to the rigidity of the paper, and the alignment performance of the paper P is deteriorated. . Also, if the further basis weight using a large sheet P 350~400g / m ² degree and basis weight, the basis weight of the above-described setting a large contact pressure than the contact pressure of 200 g / m ² about the paper P It is preferable.

  As described above, in this example, wrinkles of the paper P are generated by controlling the pressure contact force variable mechanism unit 300 and varying the pressure contact force of the steering rollers 80 and 81 during the abutting bend correction operation and the steering bend correction operation. It is possible to obtain both the effects of preventing the above and improving the matching performance at the time of abutment. Further, as described above, it is preferable to vary the pressure contact force of the steering rollers 80 and 81 in accordance with the basis weight of the paper P and the sliding resistance with the guide plate due to the surface property of the paper during the abutting and bending correction operation. . In order to prevent the paper P from passing through as the basis weight or sliding resistance of the paper P increases, the pressure contact force variable mechanism unit 300 is controlled so that the pressure contact force of the steering rollers 80 and 81 is set larger. Note that the pressure contact force may be varied according to the size of the paper P, for example.

[Block Configuration Example of Image Forming Apparatus]
FIG. 7 shows a block configuration example of the image forming apparatus 100. As illustrated in FIG. 7, the image forming apparatus 100 includes a control unit 50 that controls the overall operation of the image forming apparatus 100. The control unit 50 includes, for example, a CPU (Central Processing Unit) 52, a ROM (Read Only Memory) 54, a RAM (Random Access Memory) 56, and the like. The CPU 52 reads out a program stored in the ROM 54, develops it in the RAM 56, and executes it, thereby executing an image forming process, an abutting curve correction, and a steering curve correction operation.

  The control unit 50 includes an operation display unit 62, a storage unit 64, an image forming unit 60, a sheet feeding unit 20, a loop creation sensor 92, bending detection sensors 85 and 86, a line sensor 70, steering drive motors 83 and 84, and a pressure contact force. The variable motor 302, the loop creating motor 93, the shift roller driving motor 40, the thrust moving motor 42, and the shift roller pressing portion 44 are connected to each other.

  The operation display unit 62 includes a touch panel that employs, for example, a capacitance method, a resistance film method, and the like, detects input information based on a user input operation, and supplies an operation signal to the control unit 50. For example, the operation display unit 62 accepts various conditions of the image forming process such as the basis weight of the paper P and the paper size input by the user, and accepts the presence / absence of the setting of the abutting bend correction operation or the steering bend correction operation. Then, an operation signal based on the input information is supplied to the control unit 50.

  The storage unit 64 is composed of, for example, a semiconductor memory, an HDD (Hard Disk Drive), or the like. The storage unit 64 stores, for example, a table in which the basis weight of the paper P and the pressure contact force of the steering rollers 80 and 81 corresponding to each basis weight are associated with each other, which is used during the steering bend correction operation. In the pressing force, for example, each driving pattern of the pressing force variable motor 302 corresponding to the basis weight of the paper P or the like is stored.

  The image forming unit 60 includes, for example, image forming units 10Y, 10M, 10C, and 10K, and executes image forming processing based on control information supplied from the control unit 50. The paper feeding unit 20 feeds the paper P corresponding to the paper size information from the paper feeding unit 20 to the image forming unit 60 based on the paper size information input from the operation display unit 62 or the like.

  The loop creation sensor 92 detects the leading edge of the paper P that passes through the loop creation sensor 92 at the time of abutting bend correction and supplies a detection signal to the control unit 50.

  The bend detection sensor 85 detects the paper P passing through the bend detection sensor 85 in the steering bend correction control and supplies a detection signal to the control unit 50. The bend detection sensor 86 detects the paper P passing through the bend detection sensor 86 in the steering bend correction control and supplies a detection signal to the control unit 50. As a result, the passage time (bending amount) of the two leading ends in the orthogonal direction D2 (width direction) of the paper P passing through the bending detection sensors 85 and 86 is detected.

  The line sensor 70 measures the amount of positional deviation with respect to a preset reference position at the side edge of the paper P conveyed from the shift roller 30 to the secondary transfer unit 36, and uses the detection signal obtained by this measurement as a control unit. 50.

  The pressure contact force variable motor 302 is driven to rotate during the abutting and bending correction operation, thereby driving the driven rollers 80B and 81B constituting the steering rollers 80 and 81 by the urging force of the leaf spring 310 (see FIG. 4) as drive rollers 80A and 81A. Pressure contact. The pressure contact force of the steering rollers 80 and 81 is set to a value (maximum) at which the conveyed paper P cannot pass. Further, the pressure contact variable motor 302 is rotationally driven so as to have a pressure contact force (medium) that allows the sheet P to be nipped and conveyed during the steering bending correction operation.

  The loop creation motor 93 stops the loop creation rollers 90 and 91 after a lapse of a certain time from when the paper P is detected by the loop creation sensor 92 during the abutting and bending correction operation. The certain period is the time from when the leading edge of the paper P is abutted against the steering rollers 80 and 81 until a loop is formed on the paper P. In addition, the loop creation motor 93 rotates the loop creation rollers 90 and 91 at a predetermined linear speed and transports the paper P along the transport path, for example, during a steering bend correction operation. Of course, the nip of the loop forming rollers 90 and 91 may be released when the steering curve is corrected.

  The steering drive motor 83 is driven based on a drive signal supplied from the control unit 50 to rotate the steering roller 80 when steering bend correction control is performed. The steering drive motor 84 is driven based on a drive signal supplied from the control unit 50 to rotate the steering roller 81 when steering bend correction control is performed.

  The pressure contact force variable motor 302 presses the driven rollers 80B and 81B constituting the steering rollers 80 and 81 against the drive rollers 80A and 80B, or releases the pressure contact during a thrust movement by the shift roller 30 that will be described later. . Further, the variable pressing force motor 302 adjusts the pressing force of the steering rollers 80 and 81 by controlling the driving according to the basis weight of the paper P in accordance with an instruction from the control unit 50.

  The shift roller drive motor 40 is driven based on a drive signal supplied from the control unit 50, and controls the rotation and stop of the shift roller 30. The thrust moving motor 42 is driven based on a drive signal supplied from the control unit 50, and moves the shift roller 30 in an orthogonal direction D2 orthogonal to the sheet passing direction D1 of the sheet P via a drive transmission means such as a gear. . The shift roller pressure contact portion 44 is configured by a solenoid, a motor, or the like, and presses the driven roller 32 against the drive roller 34 or releases the pressure contact. As a result, the sheet P is nipped by the shift roller 30 and is thrustly moved in the orthogonal direction D2 orthogonal to the sheet passing direction D1 of the sheet P, and the sheet P is moved to the normal image forming position, so that the sheet P is offset. Is corrected.

[Timing chart at the time of bump bend correction and steering bend correction]
FIG. 8 shows a timing chart at the time of the collision bend correction operation and the steering bend correction operation. The paper P fed from the paper feeding unit 20 is conveyed to the steering rollers 80 and 81 by the loop creation rollers 90 and 91 and the like. Here, since it takes time to separate the sheets P one by one in the sheet feeding unit 20, the loop forming roller 90 is increased so that the conveyance speed to the steering rollers 80 and 81 that perform the abutting and bending correction operation is increased. , 91 is controlled by a loop creation motor 93. In this example, the conveyance speed of the paper P is set to the conveyance speed V1.

  When the paper P is conveyed by the loop creation rollers 90, 91, etc., the leading edge of the paper P is detected by the loop creation sensor 92 at time t1 (FIG. 8C). When the paper P is detected by the loop creation sensor 92, an ON detection signal indicating paper detection is supplied to the control unit 50. The control unit 50 supplies a control signal for stopping the loop creation rollers 90 and 91 to the loop creation motor 93 after a predetermined time Ta has elapsed from the detection of the paper P. The loop generation motor 93 gradually decelerates by starting to stop driving based on the control signal from the control unit 50 at time t2, and stops at time t3 (FIG. 8D). Here, the fixed time Ta is a time from time t1 to time t2, and the leading edge of the paper P is moved to the steering rollers 80 and 81 by the fixed time Ta and the time from t3 when the loop creation motor 93 stops. A paper loop is formed by abutting.

  When the abutting and bending correction operation is completed by forming the loop of the paper P, the control unit 50 supplies a drive signal to each of the steering drive motors 83 and 84 and the loop creation motor 93. As a result, at time t4, the steering drive motors 83 and 84 and the loop creation motor 93 are simultaneously driven at the conveyance speed V2 at which the steering curve correction operation is performed (FIGS. 8D, 8E, and 8F). )). The conveyance speed V2 is set to a speed slower than the conveyance speed V1.

  When the steering drive motors 83 and 84 and the loop creation motor 93 are driven, the conveyance of the paper P stopped by the loop creation rollers 90 and 91 is resumed. In this example, a large bend of the sheet P is corrected by the abutting bend correction operation, but a slight bend remains, and the left end side of the sheet P (the lower end side of the sheet P in FIG. 2) comes first. Assume that you are moving forward and skewing. Therefore, at the time t5, the left edge (lower side in FIG. 2) of the paper P is first detected by the paper bending detection sensor 85 (FIG. 8A), and then at the time t6, the paper bending detection sensor 86 detects the paper P. The right tip (upper side in FIG. 2) is detected (FIG. 8B). Each detected signal is supplied to the control unit 50 with a time difference (paper bending amount) ts.

  The control unit 50 calculates the rotational speeds of the steering drive motors 83 and 84 from the time difference ts of the detection signals supplied from the paper skew detection sensors 85 and 86 and the transport speed of the paper P, respectively. In this example, since the left end side (lower side in FIG. 2) of the paper P is advanced, a drive signal for reducing the rotation speed of the steering roller 80 is generated and supplied to the steering drive motor 83. As a result, the steering drive motor 83 decelerates, so that the conveyance speed by the steering roller 80 also decelerates (see S in FIG. 8F). For example, in this example, the steering roller 80 is driven at the conveyance speed decelerated by the time Tb, and is controlled so as to return to the normal conveyance speed after the elapse of the time Tb. In this way, the steering rollers 80 and 81 are independently driven in accordance with the amount of bending of the paper P, whereby the steering bending correction operation is performed.

  When the paper P is conveyed by the steering rollers 80 and 81, the paper P passes through the loop creation sensor 92 at time t7, and the output is turned off (FIG. 8C). When the paper P is detected by the loop creation sensor 92, a detection signal indicating paper non-detection is supplied to the control unit 50, and a drive signal for returning the loop creation rollers 90 and 91 to the conveyance speed V1 from the control unit 50 is a loop. It is supplied to the creation motor 93. This is to accept the next paper P. At time t7, the loop creation motor 93 accelerates the rotation based on the drive signal from the control unit 50 and transports the paper P at the transport speed V1 (FIG. 8D).

  When the steering bend correction operation is completed, the control unit 50 supplies a drive signal for stopping the steering rollers 80 and 81 to the steering drive motors 83 and 84, respectively. At time t8, the steering drive motors 83 and 84 stop the steering rollers 80 and 81 based on the drive signal from the control unit 50 (FIGS. 8E and 8F). Thereafter, when the paper P passes through the shift roller 30, the paper P passes through the paper bending detection sensors 85 and 86 at time t9 and the output is turned off (FIGS. 8A and 8B). . At this time, since the skew of the paper P is corrected, the outputs of the paper skew detection sensors 85 and 86 are turned off substantially simultaneously.

[Operation example of image forming apparatus]
FIG. 9 is a flowchart illustrating an example of the operation of the image forming apparatus 100 during the abutting bend correction operation and the steering bend correction operation. In step S100, the control unit 50 sets the pressure contact force of the steering rollers 80 and 81 to “maximum” during the collision bend correction operation. For example, the control unit 50 controls the pressure contact force variable motor 302 to press the driven roller 80B to the drive roller 80A via the leaf spring 310, thereby setting the pressure contact force of the steering rollers 80 and 81 to the “maximum” state. Set (see FIG. 5C). Thereby, it is possible to stop against the steering rollers 80 and 81 without passing the conveyed paper P. When the pressure contact force of the steering rollers 80 and 81 is set to “maximum”, the process proceeds to step S102.

  In step S <b> 102, the control unit 50 determines whether or not the leading edge of the paper P has passed the loop creation sensor 92. The control unit 50 determines whether or not an ON detection signal indicating the passage of the paper P is supplied from the loop creation sensor 92. When it is determined that the leading edge of the paper P has passed the loop creation sensor 92, the control unit 50 proceeds to step S104, and when it is determined that the leading edge of the paper P has not passed the loop creation sensor 92, the paper P Continue to detect.

  In step S <b> 104, the control unit 50 determines whether or not a predetermined time Ta (see FIG. 8) has elapsed since the leading edge of the paper P has passed through the loop creation sensor 92. The predetermined time Ta is counted by, for example, a timer function of the control unit 50. During this fixed time Ta, the leading edge of the paper P is abutted against the steering rollers 80 and 81 in a pressure contact state, and a loop is formed. The control unit 50 proceeds to step S106 when it is determined that the preset fixed period T has elapsed, and when it is determined that the preset fixed period T has not elapsed, the fixed time Ta has elapsed. Continue counting until.

  In step S106, the control unit 50 stops the driving of the loop creation motor 93 when the predetermined time Ta has elapsed. The skew of the paper P is corrected using the rigidity of the paper P formed by a loop during a predetermined time after the loop creation motor 93 is stopped. When the driving of the loop creation motor 93 is stopped, the process proceeds to step S108.

  In step S108, the control unit 50 changes the setting of the pressure contact force of the steering rollers 80 and 81 from “maximum” for the abutting bend correction operation to “medium” for the steering bend correction operation in the steering bend correction operation. This is because the sheet P cannot pass when the pressing force of the steering rollers 80 and 81 is “maximum”, and the sheet P is conveyed by a predetermined frictional force between the rollers with the pressing force set to “medium”. For example, the controller 50 drives the pressure contact force variable motor 302 to reversely rotate the leaf spring 310 to slightly weaken the urging force of the driven roller 80B against the drive roller 80A, so that the pressure contact force of the steering rollers 80 and 81 is reduced. Is changed to “medium” (see FIG. 5B). When the pressure contact force of the steering rollers 80 and 81 is set to “medium”, the process proceeds to step S110.

  In step S <b> 110, the control unit 50 performs a steering bend correction operation by the steering rollers 80 and 81. Specifically, the rotational speeds of the respective steering drive motors 83 and 84 are calculated from the time difference (bending amount) ts of detection of the paper P passing through the bending detection sensors 85 and 86 and the conveyance speed of the paper P, and this calculation is performed. The bending of the paper P is corrected by independently driving the steering rollers 80 and 81 based on the rotation speed. When the steering bend correction operation ends, the process proceeds to step S112.

  In step S112, the control unit 50 releases the pressure contact between the steering rollers 80 and 81. This is because in the shift correction operation for correcting the deviation of the paper P, the shift is performed in the orthogonal direction D2 while the paper P is held between the shift rollers 30, so that it is necessary to cancel the pressure contact between the steering rollers 80 and 81 in advance. Because there is. The controller 50 drives the pressure contact force variable motor 302 to reversely rotate the leaf spring 310 to weaken the urging force, thereby separating the driven roller 80B from the drive roller 80A and releasing the pressure contact state (FIG. 5A). reference). When the pressure contact of the steering rollers 80 and 81 is released, the process proceeds to step S114.

  In step S <b> 114, the control unit 50 performs shift correction of the paper P by the shift roller 30. The control unit 50 shifts the paper P in the orthogonal direction D <b> 2 based on the detection result of the paper P of the downstream line sensor 70 and corrects the deviation of the paper P to execute the shift correction operation. By such a series of operations, the skew correction and the offset correction of the paper P are executed.

  As described above, according to the first embodiment, in the abutting and bending correction operation, the leading edge of the paper P is abutted against the steering rollers 80 and 81 to form a loop, thereby utilizing the rigidity of the paper P. Then, the paper P is corrected to a large bend, and then, in the steering bend correction operation, the remaining bend of the paper P is obtained by independently driving the steering rollers 80 and 81 based on the detection results of the bend detection sensors 85 and 86. It is possible to perform correction to finely adjust the. Accordingly, it is possible to cope with a large bending of the paper and to adjust the amount of bending (fine adjustment) of the paper P. Further, since it is not necessary to provide a plurality of bending detection sensors 85 and 86, the bending of the paper P can be corrected with high accuracy with a simple configuration and low cost.

  Further, by using the pressure contact force variable mechanism unit 300, the pressure contact force of the steering rollers 80 and 81 can be optimally adjusted for each of the abutting and bending correction operations and the steering bending correction operation. In addition, it can be executed with high accuracy. Further, for example, in the abutting and bending correction operation, the pressure contact force is varied in accordance with the basis weight of the paper P. Therefore, it is possible to reliably prevent the paper P from passing through and perform correction by abutment.

<2. Second Embodiment>
The second embodiment is different from the pressure contact force variable mechanism unit 300 of the first embodiment in that the pressure contact force variable mechanism unit 400 is provided with a shutter function. Since the other configurations and functions of the image forming apparatus 100 are the same as those in the first embodiment, common constituent elements are denoted by the same reference numerals and detailed description thereof is omitted.

[Configuration example of variable pressure contact mechanism]
FIG. 10 shows an example of the configuration of the pressure contact force varying mechanism 400 according to the second embodiment of the present invention. As shown in FIG. 10, the pressing force variable mechanism unit 400 includes a pressing force variable motor 402, a gear 404, a pressing member 406, a pressing spring 408, and a shutter member 410. The pressure contact force varying mechanism 400 is installed on the rotation shafts O1 and O2 of the steering rollers 80 and 81 as shown by the shaded portion in FIG.

  The pressure contact variable motor 402 is composed of a stepping motor, for example, and is driven to rotate based on a drive signal supplied from the controller 50. The gear 404 is arranged so that the teeth on the peripheral surface mesh with a groove formed on the rotation shaft 402 a of the variable pressure contact force motor 402, and rotates forward or reverse by driving the variable pressure contact force motor 402.

  The pressing member 406 has a substantially fan shape, one end (base end) is attached to the central axis of the gear 404, and rotates based on the rotation of the gear 404. An opening 406a is formed along the arc at the other end of the arc of the pressing member 406. A pressing spring 408 is disposed in the opening 406a, and one end of the pressing spring 408 is attached to an inner wall surface on one end side (upper end side) of the opening 406a. The rotation shaft O1 of the driven roller 80B is inserted into the opening 406a and the other end side of the pressing spring 408. The rotating shaft O1 is urged toward the driving roller 80A by the pressing spring 408 according to the rotation of the pressing member 406. As a result, the driven roller 80B attached to the rotation shaft O1 also moves to the driving roller 80A side, and the steering roller 80 is brought into pressure contact.

  The shutter member 410 is provided so as to protrude from the lower end portion on the arcuate side of the pressing member 406 toward the transport path R, and functions as a member that blocks the transport path R of the paper P and stops the paper P during the abutting and bending correction operation. To do. The shutter member 410 has a predetermined width in the orthogonal direction D2 so as to block the paper P, and plays an auxiliary role for the steering rollers 80 and 81. The shutter member 410 may be formed integrally with the pressing member 406 or may be formed separately.

[Example of operation of variable pressure contact mechanism]
FIG. 11A to FIG. 11C show an example of the operation of the pressing force varying mechanism 400. At the time of shift correction, as shown in FIG. 11A, the steering roller 80 is adjusted by controlling the pressure contact force variable motor 302 so that the driving roller 80A and the driven roller 80B are separated from each other, thereby adjusting the posture of the pressing member 406. , 81 is released. Further, the shutter member 410 integrally formed with the pressing member 406 is also set at a position retracted from the transport path R. As a result, when the paper P is shifted in the orthogonal direction D2 by the shift roller 30, the paper P is not held between the steering rollers 80 and 81. Therefore, the paper P is not pulled or wrinkled. Is corrected.

  During the abutting and bending correction operation, the pressure contact variable motor 402 is driven by a drive signal from the control unit 50, and the pressing member 406 rotates counterclockwise via the gear 404. Along with this rotation, the pressing spring 408 comes into contact with the rotation shaft O1 of the driven roller 80B and elastically biases the rotation shaft O1 toward the drive roller 80A. When the rotating shaft O1 is energized, the driven roller 80B attached to the rotating shaft O1 moves to the driving roller 80A side, and the driven roller 80B is pressed against the driving roller 80A as shown in FIG. 11B. State.

  As the pressing member 406 further rotates, as shown in FIG. 11C, the pressure contact force by the driven roller 80B further increases, and the pressure contact force changes from “medium” to “maximum”. As a result, the paper P can be reliably stopped without passing the paper P to form a loop. At this time, the driven roller 80B abuts on the driving roller 80A and the downward movement is restricted, so that the pressing spring 408 is compressed by the rotating shaft O1, and only the pressing member 406 moves to the driving roller 80A side. As the pressing member 406 moves, the shutter member 410 integrally formed with the pressing member 406 also moves downward, and stops at a position where the shutter member 410 blocks the conveyance path R. As a result, the conveyance of the paper P can be interrupted by the shutter member 410 in addition to the nip of the steering roller 80.

  When the steering roller is corrected, the control unit 50 reversely rotates the pressure contact force variable motor 402, and as a result, the pressing member 406 moves to a position away from the driving roller 80A as shown in FIG. The biasing force of the pressing spring 408 against the rotation axis O1 of the driven roller 80B is slightly weakened. As a result, the pressure contact force of the steering roller 80 is changed from “maximum” to “medium”, and is a pressure contact force that allows the paper P to pass through with a predetermined frictional force. Further, due to the upward movement of the pressing member 406, the shutter member 410 integrally formed with the pressing member 406 also moves upward, and the shutter member 410 moves to a position retracted from the transport path R.

  As described above, according to the second embodiment, the pressure contact force variable mechanism 400 is provided with the shutter member 410 for blocking the transport path R. Thus, the conveyance path R of the paper P can be blocked, and the conveyance path R can be blocked by the shutter member 410 as well. Accordingly, it is possible to reliably form a loop by abutting the leading edge of the paper P, and to correct the bending of the paper P with high accuracy.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention. For example, in the above embodiment, the transmissive sensors are used for the bending detection sensors 85 and 86 and the loop creation sensor 92, but a reflective sensor may be used. In addition, the pressure contact force variable mechanisms 300 and 400 are not limited to the above configuration as long as the pressure contact force of the steering rollers 80 and 81 can be varied.

30 Shift roller (third roller member)
50 control unit 70 line sensor (third detection sensor)
80, 81 Steering roller (first roller member)
85,86 Bending detection sensor (first detection sensor)
90, 91 Loop creation roller (second roller member)
92 Loop creation sensor (second detection sensor)
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 300,400 Pressing force variable mechanism part 410 Shutter member 500 Conveyance apparatus

Claims (9)

A plurality of first detection sensors which are arranged at a predetermined interval in a direction perpendicular to the paper passing direction and measure the amount of bending of the conveyed paper;
A plurality of first roller members provided upstream of the first detection sensor and disposed at a predetermined interval in a direction orthogonal to the sheet passing direction;
A second detection sensor that is provided on the upstream side of the first roller member and detects the sheet conveyed to the first roller member;
And a control unit that performs a first correction operation for independently driving the first roller member based on the amount of bending of the sheet measured by the first detection sensor to correct the bending of the sheet. ,
The controller stops or reversely rotates the first roller member based on the detection result of the paper by the second detection sensor before performing the first correction operation. A transport device that performs a second correction operation for correcting the bending of the paper by abutting the front end against the first roller member to form a loop. A pressure contact force varying portion that varies the pressure contact force of the first roller member;
The said control part controls the said press-contact force variable part so that a said 1st roller member will be in a press-contact state, when the said 1st and 2nd correction | amendment operation | movement is performed. Conveying device. The controller may vary the pressure contact force so that the pressure contact force of the first roller member during the second correction operation is greater than the pressure contact force of the first roller member during the first correction operation. The conveyance device according to claim 2, wherein the conveying unit is controlled. In the second correction operation, the control unit is configured to change the pressure contact force of the first roller member according to a basis weight of the paper or a sliding resistance with a guide plate constituting a conveyance path. The conveyance device according to claim 2 or 3, wherein the variable unit is controlled. A pressure contact force varying portion having a shutter member that varies the pressure contact force of the first roller member and blocks the sheet conveyance path according to the variation of the pressure contact force;
In the second correction operation, the control unit controls the pressure contact force variable unit so that the first roller member is in a pressure contact state and the shutter member blocks the conveyance path. The transport apparatus according to claim 1. A second roller member provided on the upstream side of the second detection sensor;
2. The control unit according to claim 1, wherein, in the second correction operation, the rotation of the second roller member is stopped after a predetermined time has elapsed since the detection of the paper by the second detection sensor. The conveying apparatus according to any one of claims 5 to 6. The controller rotates the second roller member at a first conveyance speed when the second correction operation is completed, and the second roller member is turned off when the output of the second detection sensor is turned off. The conveying apparatus according to claim 6, wherein the conveying device is rotated at a second conveying speed that is faster than the first conveying speed. A third roller member provided on the downstream side of the first detection sensor;
A third detection sensor provided on the downstream side of the third roller member and measuring a deviation amount of the paper;
The control unit controls the third roller member to shift the sheet in the orthogonal direction based on a deviation amount of the sheet measured by the third detection sensor. The conveyance apparatus as described in any one of Claims 1-7. A transport apparatus according to claim 1;
An image forming apparatus comprising: an image forming unit that forms an image on the sheet conveyed by the conveying device.

Images