JP2010247929A - Paper conveying mechanism and image formation device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent improper rotation of a resist roller generated by abutment of a sheet tip onto a nip part when sheets are aligned by giving a rotary load to the resist roller with a simple and inexpensive constitution. <P>SOLUTION: This image formation device 1 has a pair of resist rollers 35 constituted by a drive roller 41 and a driven roller 42 pressure contacting the drive roller, and delivers a sheet S at a predetermined timing. In a sheet delivery part 4 of the device, a rotary shaft 61 of the drive roller is provided with a twist coil spring 64 fitted and inserted in a coil part 71. The twist coil spring generates sliding friction between itself and the rotary shaft when the drive roller rotates in the delivery direction of the sheet, so as to give a predetermined rotary load to the drive roller. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet conveying mechanism having a pair of registration rollers that conveys a sheet at a predetermined timing, and an image forming apparatus including the same.

  Conventionally, in an image forming apparatus such as a printer, a facsimile machine, a copier, and a multifunction machine, a sheet having a registration roller pair that conveys the aligned sheet at a predetermined timing in order to transfer a toner image to a desired position on the sheet. Those equipped with a transport mechanism have become widespread. In this type of paper transport mechanism, the front end of the paper is abutted against the nip portion of the registration roller pair, and the paper is aligned (including skew correction etc.), and the toner image on the image carrier is transferred. The registration roller pair is driven in accordance with the transfer timing to feed the paper.

  Since the leading edge of the paper against the nip portion of the registration roller pair is performed by using the restoring force of the bent paper, the paper having strong stiffness (high restoring force) such as a postcard, an OHP sheet, and a thick paper is used. In this case, the pair of registration rollers may be rotated by the abutment, which may cause a problem in sheet alignment and conveyance. Further, since the driving force of the registration roller pair is transmitted from a driving source (motor, etc.) via a gear, an electromagnetic clutch, etc., if the driving timing of the registration roller pair shifts due to backlash of the gear, the position of the paper There may be problems with alignment and transport.

  In order to prevent such inappropriate rotation of the registration roller pair and rattling due to gear backlash, it is necessary to apply an appropriate rotational load to the registration roller pair. Generally, in order to apply a rotational load to the registration roller pair, the pressing force of the driven roller is increased to increase the pressure contact force between the registration rollers. However, when the pressing force is increased, the shaft of each roller is easily bent, and the sheet conveying force differs between the center and both sides of the roller, making it impossible to convey the sheet properly. For this reason, it is necessary to increase the shaft diameter of the roller pair to make the rollers difficult to bend, but the cost increases and the weight of the apparatus also increases. In order to solve this problem, there is a technique for applying a rotational load to the registration roller pair without changing the shaft diameter of the registration roller.

  For example, a rubber oil seal is fitted to the registration roller shaft in a frictional engagement state, the outer portion of the oil seal is fixed to a predetermined fixing portion, and the oil seal and the shaft are rotated when the registration roller shaft rotates. There is known a paper transport mechanism in which a rotational load is generated by sliding friction (see Patent Document 1).

Japanese Utility Model Publication No. 2-145253

  However, in the conventional technique described in Patent Document 1, when a larger rotational load is applied to the registration roller, there is a problem that the wear of the rubber oil seal is increased due to sliding friction with the shaft, and the life is shortened. there were. In the above prior art, it is conceivable to increase the rotational load of the registration roller by increasing the number of oil seals to be installed, but in that case, the number of parts increases and the cost of the apparatus increases, and the installation of oil seals also increases. There is a problem that the space becomes large and the apparatus becomes large. Further, in the above prior art, since the rotational load is not applied to the driven roller in the registration roller pair, for example, measures such as increasing the shaft diameter and increasing the pressure contact force between the registration rollers as described above are taken. Otherwise, there was a problem that improper rotation of the driven roller could not be prevented.

  The present invention has been devised in view of such problems of the prior art, and by applying a rotational load to the registration roller with a simple and inexpensive configuration, the nip at the leading end of the sheet is adjusted during sheet alignment. It is a main object of the present invention to provide a sheet transport mechanism that can prevent inappropriate rotation of a registration roller caused by abutment on a portion and realize a reduction in the weight of the apparatus, and an image forming apparatus including the sheet transport mechanism.

  The paper transport mechanism of the present invention is a paper transport mechanism that includes a pair of registration rollers including a driving roller and a driven roller that is in pressure contact with the driving roller, and transports the paper at a predetermined timing. The torsion coil spring includes a torsion coil spring that is inserted into a coil portion, and the torsion coil spring generates sliding friction with the rotation shaft when the drive roller rotates in the paper transport direction. A predetermined rotational load is applied to the driving roller.

  As described above, according to the present invention, by applying a rotational load to the registration roller with a simple and inexpensive configuration using a torsion coil spring, the registration caused by abutment of the leading end of the sheet on the nip portion when the sheet is aligned. There is an excellent effect that inappropriate rotation of the roller can be prevented.

Schematic configuration diagram of an image forming apparatus according to an embodiment Schematic diagram showing the configuration of the paper transport unit according to the embodiment Plan view of a pair of registration rollers according to an embodiment The perspective view which shows the edge part of the one side of the drive roller which concerns on embodiment The schematic diagram which shows the fixing structure of the torsion coil spring which concerns on embodiment The top view which shows the example of a change of the support structure of the driven roller which concerns on embodiment FIG. 3 is a timing chart showing the operation status of the paper transport unit according to the embodiment.

  A first invention made to solve the above problems is a paper transport mechanism that has a pair of registration rollers including a driving roller and a driven roller pressed against the driving roller, and transports the paper at a predetermined timing. And a torsion coil spring in which a rotating shaft of the driving roller is fitted and inserted into a coil portion, and the torsion coil spring slides between the rotating shaft and the rotating shaft when the driving roller rotates in the paper transport direction. In this case, a predetermined rotational load is applied to the drive roller.

  According to this, by applying a rotational load to the registration roller with a simple and inexpensive configuration using a torsion coil spring, the registration roller is improperly caused by abutting the nip portion at the leading edge of the paper at the time of paper positioning. Rotation can be prevented. Moreover, since the pressing force of the driven roller can be reduced, the roller diameter of the registration roller pair can be reduced, and the cost can be reduced and the apparatus can be reduced in weight.

  Moreover, 2nd invention can be set as the structure by which the drive roller and the said driven roller were mutually connected with the gear.

  According to this, it becomes possible to apply a rotational load from the driving roller to the driven roller via the gear, and only the driven roller that is not subjected to the rotational load rotates alone when the paper is abutted against the nip portion. Therefore, inappropriate rotation of the registration roller can be prevented more reliably.

  The third aspect of the invention may further include a pressing unit that presses the axial intermediate portion of the driven roller toward the pressure contact side with respect to the driving roller.

  According to this, since it is possible to prevent the driven roller from being bent due to abutment of the leading end of the paper against the nip portion, it is possible to set the shaft diameter of the driven roller to be smaller, thereby reducing the cost and the weight of the apparatus. realizable.

  The fourth aspect of the invention further includes control means for controlling the drive of the drive roller, and the control means drives and stops the drive roller before the registration roller pair starts conveying the paper. It can be configured to execute.

  According to this, when the driving force is transmitted from the driving source (such as a motor) to the driving roller via the gear, it is possible to make the tooth surfaces of the gears mesh with each other in advance. It is possible to prevent the drive timing of the registration roller pair from shifting due to backlash.

  The fifth aspect of the invention further includes a spring fixing member that fixes the torsion coil spring, the spring fixing member including a groove portion in which an arm portion formed on one end side of the coil portion is loosely fitted, and the groove portion. It can be set as the structure which has a press part which presses the said arm part toward one side edge.

  According to this, since it is possible to easily insert the arm portion into the groove portion and guide the movement of the arm portion to the fixing position, it is easy to fix the torsion coil spring, and the pressing portion and the side edge of the groove portion It is possible to stably fix the arm portion between them, eliminating backlash at the mounting portion of the arm portion, and preventing the drive timing of the registration roller pair from shifting.

  According to a sixth aspect of the present invention, the rotating shaft of the drive roller has a stepped portion formed by reducing the diameter of one end portion of the driving roller inserted into the coil portion of the torsion coil spring and reducing the diameter of the end portion. The torsion coil spring has a configuration in which the other end side of the coil part where the arm part is not formed is in contact with the step part, and the arm part is pressed toward the step part by a bottom edge of the groove part. It can be.

  According to this, it is possible to regulate the relative movement of the torsion coil spring in the axial direction with respect to the rotation shaft of the drive roller without providing a special member.

  A seventh invention is an image forming apparatus provided with the paper transport mechanism according to any one of the first to sixth inventions.

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

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is housed in an image forming unit 2 that forms a color image on a sheet through processes of charging, exposure, development, transfer, and fixing, and a paper feed cassette 3 for the image forming unit 2. And a paper transport unit (paper transport mechanism) 4 for feeding the paper S at an appropriate timing. The sheets S accommodated in the lower sheet feeding cassette 3 are sequentially conveyed to the image forming unit 2 via a sheet conveying path A extending in the vertical direction, and a desired image is formed in the image forming unit 2 and then discharged. The paper is discharged to the paper discharge unit 5 via the path B. When images are formed on both sides of the sheet S, the sheet S sent out from the image forming unit 2 is returned to the upstream side of the sheet conveyance path A via the reversing path C, and the front and back are reversed. Then, it is sent again to the image forming unit 2.

  The image forming unit 2 includes a plurality of process units 11 to 14 that respectively form toner images of yellow, magenta, cyan, and black, and the photosensitive drums 11 a to 14 a in the process units 11 to 14. An LSU (Laser Scanning Unit) 15 that scans an image surface with a light beam for exposure and a toner image for each color formed on each photosensitive drum 11a to 14a in each process unit 11 to 14 are sequentially transferred. The intermediate transfer belt 16 is combined, and the photosensitive drums 11 a to 14 a for each color are arranged along the intermediate transfer belt 16 in a tandem structure.

  In each of the process units 11 to 14, the electrostatic latent image is scanned from the LSU 15 with the exposure light beam on the image forming surfaces of the photosensitive drums 11a to 14a uniformly charged by the chargers 11b to 14b. An image is formed, and the electrostatic latent images on the respective photoconductive drums 11a to 14a are developed with the respective color toners supplied from the respective developing units 11c to 14c, and single color toner images for the respective colors are formed on the respective photoconductive drums 11a to 11a. 14a is formed on the image forming surface.

  The intermediate transfer belt 16 is supported by being wound around two rollers 21 and 22, and the intermediate transfer belt 16 is pressed inside the intermediate transfer belt 16 so that the toner images on the photosensitive drums 11 a to 14 a are applied to the intermediate transfer belt 16. Primary transfer rollers 24 to 27 for each color to be transferred are provided. A secondary transfer roller 28 for transferring the toner image on the intermediate transfer belt 16 to the paper S is disposed on the side of the end of the intermediate transfer belt 16. The sheet S on which the toner image has been transferred by the secondary transfer roller 28 is conveyed to a fixing device 29 and subjected to processing for fixing the toner image by heat and pressure.

  FIG. 2 is a schematic diagram showing the configuration of the paper transport unit 4 in the image forming apparatus 1 shown in FIG. In the paper transport unit 4, after the paper S in the paper feed cassette 3 is taken out by the pickup roller 31, the taken paper S is sent out to the paper transport path A by the paper feed roller pair 32. A registration sensor 36 that detects the position of the sheet is provided in the vicinity of the upstream side of the registration roller pair 35. Based on the detection result of the registration sensor 36, the sheet S is abutted against the nip portion of the registration roller pair 35. Thereafter, the sheet is further conveyed by the intermediate roller pair 34 and the sheet is bent, and then the sheet conveyance by the intermediate roller 34 is stopped. As a result, alignment including skew correction is performed. Thereafter, the sheet S is sent out at an appropriate timing in synchronization with the image on the intermediate transfer belt 16.

  The registration roller pair 35 includes a driving roller 41 and a driven roller 42 that is in pressure contact with the driving roller 41. The driving roller 41 is driven by the driving force of the motor 43. Between the driving roller 41 and the motor 43, a registration clutch 44 that interrupts transmission of power from the motor 43 to the driving roller 41 is provided. The operations of the motor 43 and the registration clutch 44 are controlled by a controller 45 (control means). Note that the control controller comprehensively controls not only control of the motor 43 and the like, but also processing of each unit of the image forming apparatus 1.

  Similar to the registration roller pair 35, the paper feed roller pair 32 includes a driving roller 51 and a driven roller 52, and the intermediate roller pair 34 includes a driving roller 53 and a driven roller 54. The driving rollers 51 and 53 are driven by the driving force of the motor 43, and a paper feeding clutch 55 that intermittently transmits power from the motor 43 to the driving rollers 51 and 53 between the driving rollers 51 and 53 and the motor 43. And an intermediate clutch 56 are provided. The sheet feeding clutch 55 and the intermediate clutch 56 have the same configuration as the registration clutch 44, and their operations are controlled by the controller 45.

  3 is a plan view of the registration roller pair 35 shown in FIG. 2, FIG. 4 is a perspective view showing one end side of the drive roller 41, and FIG. 5 shows a fixing structure of the torsion coil spring 64 shown in FIG. It is a schematic diagram.

  As shown in FIG. 3, the drive roller 41 has a plurality of metal rotating shafts 61 that are rotatably supported at both ends by bearings 60 a and 60 b, and a plurality of driving rollers 41 are arranged at predetermined intervals in the axial direction of the rotating shaft 61. And a rubber roller 62 made of rubber. The rotating shaft 61 has a torsion coil spring 64 attached to one end 63 having a reduced diameter, and a gear 67 and a resist clutch 44 attached to the other end 65 having a reduced diameter. The driving force of the motor 43 (see FIG. 2) is transmitted to the gear 68 that meshes with the gear 67 so that power can be transmitted.

  The registration clutch 44 is an electromagnetic clutch, and when the drive roller 41 is driven, the rotation shaft 61 and the gear 67 are connected by applying a voltage to an excitation coil (not shown) to connect between the gear 67 and the gear 68. Allows power transmission.

  The torsion coil spring 64 is formed of a wire made of spring steel, and has a coil portion 71 wound with a predetermined diameter, and a linear arm portion 72 formed on one end side of the coil portion 71. . The coil portion 71 has an inner diameter that is slightly smaller than the outer diameter of the end portion 63 of the drive roller 41 that is inserted into the coil portion 71, and the other end side where the arm portion 72 is not formed is formed by the reduced diameter of the end portion 63. It is in the state which contact | abutted to the step part 73 made. With such a configuration, the relative movement in the axial direction of the torsion coil spring 64 with respect to the rotation shaft 61 of the drive roller 41 can be restricted without providing a special member.

  The support wall 81 that supports the bearing 60 a of the drive roller 41 is provided with a spring fixing member 82 that fixes the arm portion 72 of the torsion coil spring 64. 4 and 5, the spring fixing member 82 includes a groove portion 85 and a vertical piece 87 disposed adjacent to the groove portion 85, and the groove portion 85 and the vertical piece 87 are inward from the support wall 81. It is extended toward.

  When the arm portion 72 of the torsion coil spring 64 is fixed, the groove portion 85 has an inner surface 81a of the support wall 81 as a bottom edge, a tip portion 85a of an inclined piece extending in the vertical direction, and a vertical piece facing the tip portion 85a. The upper end portion 86a is defined as a side edge. When the arm portion 72 of the torsion coil spring 64 is fixed, the arm portion 72 is loosely fitted in the groove portion 85. The arm portion 72 loosely fitted in the groove portion 85 is pressed by the distal end portion (pressing portion) 87a of the vertical piece 87 toward the distal end portion 85a of the inclined piece (that is, one side edge of the groove portion 85). Is done. Thereby, the arm part 72 is clamped between the front-end | tip part 85a of an inclination piece, and the front-end | tip part 87a of the vertical piece 87 in the state bent a little in the direction shown by the arrow X in FIG.

  With such a configuration, the arm portion 72 can be easily inserted into the groove portion to guide the movement of the arm portion 72 to the fixing position. Therefore, the fixing operation of the torsion coil spring 64 is facilitated, and the vertical piece 87 is used. The arm portion 72 can be stably fixed between the leading end portion 87a of the groove portion 85 and the leading end portion 85a of the groove portion 85, rattling at the mounting portion of the arm portion 72 is eliminated, and the drive timing of the registration roller shaft 61 is shifted. Can be prevented.

  Further, as shown in FIG. 3, the driven roller 42 corresponds to the position of the metal rotation shaft 91 rotatably supported at both ends by bearings 90a and 90b and the roller portion 62 of the drive roller 41. And a plurality of synthetic resin roller portions 92 arranged at predetermined intervals in the axial direction of the rotation shaft 91. The bearings 90a and 90b are supported so as to be movable in a direction approaching or separating from the drive roller 41 by a support member 93 having a substantially U-shape in plan view. The bearings 90 a and 90 b are pressed in a direction in which the roller portion 92 of the driven roller 42 is pressed against the roller portion 62 of the driving roller 41 by compression springs 94 a and 94 b attached to the support member 93. Further, the connection gear 95 provided on one end side of the rotation shaft 91 is in a state of being engaged with the connection gear 96 provided on one end side of the rotation shaft 61 of the drive roller 41. Thus, since the driving roller 41 and the driven roller 42 are connected to each other by the connecting gears 95 and 96, there is an advantage that the driven roller 42 can be reliably rotated according to the rotation of the driving roller 41.

  As an example of a change in the support structure of the driven roller 42 as described above, as shown in FIG. 6, the axial intermediate portion (center in FIG. 6) of the driven roller 42 is pressed against the pressure contact side with respect to the drive roller 41. A configuration in which the pressing mechanism (pressing means) 101 is provided on the support member 93 is also possible. The pressing mechanism 101 extends from a contact member 102 that contacts the rotation shaft 91 of the driven roller 42, a compression spring 103 that biases the contact member 102 toward the rotation shaft 91, and a support member 93. And a holder 104 that holds the contact body 102 and the compression spring 103. The movement range of the contact body 102 is limited to a range in which the pair of locking pieces 105 protruding outward can move the widened portion 104 a of the holder 104.

  With such a configuration, it is possible to prevent the driven roller 42 from being bent due to the driven roller 92 being pressed by the springs 94a and 94b, so that the shaft diameter of the driven roller 42 can be set smaller.

  In the above configuration, when the drive roller 41 rotates in the paper conveyance direction (see arrow Y in FIG. 5), the rotation direction is the winding direction of the coil portion 71 starting from the arm portion 72 of the torsion coil spring 64. The torsion coil spring 64 generates sliding friction between the inner peripheral surface of the coil portion 71 and the outer peripheral surface of the end portion 63 of the drive roller 41, thereby causing a predetermined friction with respect to the drive roller. A rotational load is applied. At this time, since the driven roller 42 is connected to the driving roller 41 via the connecting gears 95 and 96, a rotational load is applied from the driving roller 41.

  As described above, in the paper transport unit 4, a rotational load is applied to the driving roller 41 with a simple and inexpensive configuration using the torsion coil spring 64, so that the paper is aligned with the nip portion N at the front end of the paper when the paper is aligned. Inappropriate rotation of the registration roller pair 35 caused by the abutting can be prevented, and the shaft diameters of the driving roller 61 and the driven roller 42 can be reduced, so that the cost and weight of the apparatus can be reduced.

  FIG. 7 is a timing chart showing the operation status of the paper transport unit 4 shown in FIG. In the present embodiment, driving and stopping of the driving roller 41 are temporarily executed before the conveyance of the sheet S by the registration roller pair 35 is started.

  When the operator of the image forming apparatus 1 executes a print instruction at time T0, the motor 43 is activated (ON) at time T1. At the same time, the registration clutch 44 is turned on (power transmission state), and thereafter is turned off when a predetermined time has elapsed. At this time, the drive roller 41 rotates in the paper transport direction at time T1, and then stops its rotation. Although the specified time can be set arbitrarily, it may be a short time such that the drive roller 41 is rotated by a slight angle.

  Thereafter, the paper feed clutch 55 is turned on, and the paper S in the paper feed cassette 3 is sent out to the paper transport path A. After the sheet S reaches the intermediate roller pair 34, the sheet feeding clutch 55 is stopped. Here, the on / off state of the intermediate clutch 56 coincides with the on / off state of the motor 43.

  Subsequently, when the leading edge of the sheet reaches the registration sensor 36 at time T2 and the sensor is turned on, the controller 45 detects the position of the sheet, and abuts the leading edge of the sheet against the nip portion of the registration roller pair 35. A predetermined bending is applied to the paper. Thus, the motor 43 is stopped (off) after correcting the skew of the sheet. Thereafter, in accordance with the timing of the image on the intermediate transfer belt 16, the motor 43 is turned on again, and the registration clutch 44 is turned on, and the sheet S is sent to the intermediate transfer belt 16 and the secondary transfer roller 28 side at an appropriate timing. .

  Thereafter, when the registration sensor 36 is turned off at time T4, the controller 45 determines that the conveyance of the sheet S by the registration roller pair 35 is completed after a predetermined time, and turns off the registration clutch 44. The motor 43 is stopped.

  As described above, since the driving roller 41 is driven and stopped at time T1 before the registration roller pair 35 starts transporting the sheet S at time T4, the tooth surfaces of the gears 67 and 72 are bitten in advance. It is possible to obtain a combined state. Therefore, it is possible to prevent the drive timing of the registration roller pair 35 (the conveyance timing of the paper S) from being shifted due to the backlash of the gears 67 and 72. This is particularly effective when the paper transport path is released during paper jam processing or the like. The driving and stopping of the driving roller 41 are not limited to those illustrated in FIG. 7, and may be performed at an arbitrary timing as long as the registration roller pair 35 is not started to convey the paper S. Is possible.

  Although the present invention has been described in detail based on specific embodiments, these embodiments are merely examples, and the present invention is not limited to these embodiments. For example, the rotational load generated on the registration roller pair by the torsion coil spring can be variously changed according to the use environment. Further, a mechanism similar to a pressing mechanism for pressing the intermediate portion in the axial direction of the driven roller toward the pressure contact side with respect to the driving roller may be provided on the driving roller side. In that case, since the bending of the driving roller can be prevented, there is an advantage that the shaft diameter of the driving roller can be set smaller.

  The paper transport mechanism and the image forming apparatus including the paper transport mechanism according to the present invention apply a rotational load to the registration roller with a simple and inexpensive configuration, so that the paper tip is abutted against the nip portion when the paper is aligned. Therefore, it is possible to prevent improper rotation of the registration rollers caused by the above, and it is useful as a sheet conveyance mechanism having a registration roller pair for conveying sheets at a predetermined timing and an image forming apparatus including the sheet conveyance mechanism.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Paper feed cassette 4 Paper conveyance part 16 Intermediate transfer belt 28 Secondary transfer roller 31 Pickup roller 32 Paper feed roller pair 34 Intermediate roller pair 35 Registration roller pair 36 Registration sensor 41 Drive roller 42 Driven roller 43 Motor 44 Registration Clutch 45 control controller (control means)
55 Feeding clutch 56 Intermediate clutch 61 Rotating shaft 62 Roller part 63 End part 64 Torsion coil spring 64 End part 71 Gear 71 Coil part 72 Arm part 72 Gear 73 Step part 82 Spring fixing member 85 Groove part 85a Tip part 86a Upper end part 87 Vertical piece 87a Tip (pressing part)
93 Support member 94a Compression spring 95 Connection gear 96 Connection gear 101 Pressing mechanism (pressing means)
102 Contact body 103 Compression spring N Nip part S Paper

Claims (7)

A sheet conveying mechanism having a registration roller pair configured by a driving roller and a driven roller pressed against the driving roller, and conveying a sheet at a predetermined timing;
A torsion coil spring in which the rotating shaft of the drive roller is fitted into the coil portion;
The torsion coil spring applies a predetermined rotational load to the driving roller by causing sliding friction with the rotating shaft when the driving roller rotates in the paper transport direction. Characteristic paper transport mechanism.   The paper transport mechanism according to claim 1, wherein the driving roller and the driven roller are connected to each other by a gear.   3. The sheet transport mechanism according to claim 1, further comprising a pressing unit that presses an intermediate portion of the driven roller in an axial direction toward a pressure contact side with respect to the driving roller. A control means for controlling the driving of the driving roller;
4. The sheet according to claim 1, wherein the control unit executes driving and stopping of the driving roller before the registration roller pair starts conveying the sheet. 5. Transport mechanism. A spring fixing member for fixing the torsion coil spring;
The spring fixing member is
The groove part in which the arm part formed in the one end side of the said coil part is loosely fitted, and the press part which presses the said arm part toward one side edge of the said groove part, It is characterized by the above-mentioned. The paper transport mechanism according to claim 4. The rotating shaft of the drive roller has a stepped portion formed by reducing the diameter of the end portion, while the one end portion having a reduced diameter is fitted into the coil portion of the torsion coil spring.
The torsion coil spring is characterized in that the other end side of the coil part where the arm part is not formed contacts the step part, and the arm part is pressed in the direction of the step part by the bottom edge of the groove part. The paper transport mechanism according to claim 5.   An image forming apparatus comprising the paper transport mechanism according to claim 1.

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