JP2021134004A - Image formation apparatus - Google Patents

Abstract

To correct skewing of a sheet while suppressing damage to the sheet.SOLUTION: A secondary roller pair 31b is disposed on the downstream side of a sheet conveyance direction from a position of a primary roller pair 31a, forms a second nip N2, and performs skew correction of a sheet while its rotation is stopped. A pivoting guide member 6 is pivotably supported in a deflection forming area that allows the sheet to be deflected at the upstream side in the sheet conveyance direction against the secondary roller pair 31b in a sheet conveyance path 300 and limits the deflection of the sheet by contacting the deflected portion in the sheet. The pivoting guide member 6 is formed on both sides of a pivoting axis 61a, which is provided at the center of the width direction in the sheet conveyance path 300 and extends in the sheet conveyance direction, and extends in the width direction and is supported so that it can be pivoted around the pivoting axis 61a.SELECTED DRAWING: Figure 6

Description

The present invention relates to an image forming apparatus having a function of correcting skew of a sheet.

The image forming apparatus includes a printing unit that forms an image on the sheet. In the image forming apparatus, the resist roller pair arranged in the sheet transport path adjusts the timing of transporting the sheet toward the printed portion by temporarily stopping the sheet.

When the sheet is transported from the resist roller pair to the printed portion in a state of being tilted with respect to the sheet transport direction, an image tilted with respect to the original direction is formed on the sheet.

Further, it is known that by transporting the sheet toward the resist roller pair in which the transport roller pair is stopped, the tip of the sheet is made to follow the resist roller pair while forming a deflection in the sheet. For example, see Patent Document 1). As a result, the skew of the sheet is corrected. In the following description, transporting the sheet toward the resist roller pair in which the transport roller pair has stopped is referred to as skew correction transport.

Japanese Unexamined Patent Publication No. 4-289881

By the way, when the sheet is skewed, the preceding first edge portion of the left and right edge portions of the tip of the sheet comes into contact with the resist roller pair, and then the subsequent second edge portion is the resist roller pair. The sheet bends by the time it reaches.

The bending of the sheet may occur not only in the portion of the sheet on the first edge portion side but also in the portion on the second edge portion side. In this case, the time difference between the first edge portion and the second edge portion reaching the resist roller pair becomes large.

When the time difference may be large, it is necessary to lengthen the skew correction transfer time. However, if the skew-corrected transport time is long, the sheet may be significantly damaged due to the large bending of the sheet.

An object of the present invention is to provide an image forming apparatus capable of correcting the skew of the sheet while suppressing damage to the sheet.

The image forming apparatus according to one aspect of the present invention includes a primary roller pair, a secondary roller pair, a printing unit, a swing guide member, and a transport control unit. The primary roller pair is arranged in a sheet transport path, forms a first nip, and rotates to convey the sheet while sandwiching it in the first nip. The secondary roller pair is arranged on the downstream side in the sheet transport direction from the position of the primary roller pair in the sheet transport path, forms a second nip, and is transported from the primary roller pair in a state where rotation is stopped. By bringing the tip of the sheet into contact with the second nip, the sheet is formed to bend in a predetermined direction, and by aligning the tip of the sheet with the second nip, skew correction of the sheet is performed. By performing and rotating, the sheet is conveyed by taking over from the primary roller pair. The printed portion forms an image on the sheet at a position downstream of the position of the secondary roller pair in the sheet transport path in the sheet transport direction. The oscillating guide member is swingably supported in a deflection forming region that allows the sheet to bend on the upstream side in the sheet conveying direction with respect to the secondary roller pair in the sheet conveying path, and the oscillating guide member is oscillatingly supported. The bending of the sheet is limited by contacting the portion. The swing guide member is provided at the center of the seat transport path in the width direction and is formed so as to extend in the width direction on both sides with respect to the swing shaft extending in the seat transport direction, and swings around the swing shaft. It is movably supported.

According to the present invention, it is possible to provide an image forming apparatus capable of correcting the skew of the sheet while suppressing damage to the sheet.

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is a block diagram showing a configuration of a control device in the image forming device according to the embodiment. FIG. 3 is a configuration diagram of a sheet detection device in the image forming device according to the embodiment. FIG. 4 is a diagram showing a sheet passing through a detection position of a sheet transport path in the image forming apparatus according to the embodiment. FIG. 5 is a configuration diagram of a portion from a primary roller pair to a secondary roller pair in the image forming apparatus according to the embodiment. FIG. 6 is a perspective view of a swing guide member in the image forming apparatus according to the embodiment. FIG. 7 is a front view of the swing guide member and its peripheral portion in the image forming apparatus according to the embodiment. FIG. 8 is a diagram showing a state in which a bent sheet comes into contact with a swing guide member in the image forming apparatus according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are examples that embody the present invention, and do not limit the technical scope of the present invention.

[Structure of image forming apparatus 10]
The image forming apparatus 10 according to the embodiment is an apparatus capable of executing a printing process for forming an image on the sheet 9. For example, the image forming apparatus 10 is a printer, a copying machine, a facsimile apparatus, or a multifunction device.

As shown in FIG. 1, the image forming apparatus 10 includes a sheet accommodating portion 1, a sheet sending device 2, a sheet conveying device 3, and a printing device 4. The printing device 4 is an example of a printing unit that executes the printing process. The sheet transfer device 3 and the printing device 4 are housed in a main body 100 which is a housing.

The sheet delivery device 2 sends out the sheets 9 housed in the seat storage unit 1 one by one to the transport path 300 in the main body 100. The transport path 300 is a sheet transport path that forms a passage for the seat 9.

The sheet transport device 3 transports the sheet 9 sent to the transport path 300 by the sheet delivery device 2 along the transport path 300. In FIGS. 3 to 8, D1 indicates a conveying direction in which the sheet 9 is conveyed, and D2 indicates a width direction orthogonal to the sheet conveying direction. The width direction D2 is the horizontal direction.

In the sheet transfer device 3, a plurality of sets of transfer roller pairs 31 rotate to convey the sheet 9 along the transfer path 300, and further discharge the sheet 9 from the transfer path 300 to the paper discharge tray 101.

The printing device 4 forms an image on the sheet 9 at the printing position P1 of the transport path 300. In the present embodiment, the printing apparatus 4 executes the printing process in an electrophotographic manner. Therefore, the printing device 4 includes an optical scanning unit 40, a photoconductor 41, a charging device 42, a developing device 43, a transfer device 45, a cleaning device 46, a fixing device 47, and the like.

The drum-shaped photoconductor 41 rotates, and the charging device 42 charges the outer peripheral surface of the photoconductor 41. The optical scanning unit 40 writes an electrostatic latent image on the outer peripheral surface of the charged photoconductor 41.

The developing device 43 develops the electrostatic latent image into a toner image by supplying toner to the outer peripheral surface of the photoconductor 41 on which the electrostatic latent image is formed. The photoconductor 41 is an example of an image carrier.

The transfer device 45 transfers the toner image on the photoconductor 41 to the sheet 9 that passes through the print position P1 of the transport path 300. The fixing device 47 pressurizes the toner image transferred to the sheet 9 while heating it. As a result, the toner image is fixed on the sheet 9.

The image forming apparatus 10 further includes a control device 8. As shown in FIG. 2, the control device 8 includes a CPU (Central Processing Unit) 81 and peripheral devices such as a RAM (Random Access Memory) 82, a secondary storage device 83, and a signal interface 84.

The CPU 81 is a processor that executes various data processing and control by executing a computer program.

The RAM 82 is a computer-readable volatile storage device. The RAM 82 primarily stores the computer program executed by the CPU 81 and data to be output and referenced in the process of executing various processes by the CPU 81.

The secondary storage device 83 is a computer-readable non-volatile storage device. The secondary storage device 83 can store and update the computer program and various data. For example, one or both of the flash memory and the hard disk drive are adopted as the secondary storage device 83.

The CPU 81 includes a plurality of processing modules realized by executing the computer program. The plurality of processing modules include a main control unit 8a, a transfer control unit 8b, a print control unit 8c, and the like.

The main control unit 8a executes start control or the like to start various processes in response to an operation on an operating device (not shown). The transfer control unit 8b controls the sheet transfer device 3. The print control unit 8c causes the printing device 4 to execute the printing process in synchronization with the transfer of the sheet 9.

The signal interface 84 converts the signals output by various sensors into digital data, and transmits the converted digital data to the CPU 81. Further, the signal interface 84 converts the control command output by the CPU 81 into a control signal, and transmits the control signal to the device to be controlled.

When the sheet 9 is transported to the print position P1 in a state of being tilted with respect to the transport direction D1, an image tilted with respect to the original direction is formed on the sheet 9. Therefore, it is important to correct the skew of the sheet 9 before the sheet 9 reaches the print position P1.

The plurality of sets of transport roller pairs 31 include a primary roller pair 31a and a secondary roller pair 31b arranged on the upstream side of the transport direction D1 with respect to the print position P1 in the transport path 300 (see FIG. 1).

The primary roller pair 31a is arranged in the transport path 300 and forms a first nip N1 which is a portion where they are in contact with each other (see FIG. 5). The primary roller pair 31a conveys the sheet 9 while sandwiching it in the first nip N1 by rotating.

The secondary roller pair 31b is arranged on the downstream side in the transport direction D1 from the position of the primary roller pair 31a in the transport path 300. The secondary roller pair 31b forms a second nip N2 where they are in contact with each other (see FIG. 5). The secondary roller pair 31b takes over from the primary roller pair 31a by rotating and conveys the sheet 9 toward the print position P1. The secondary roller pair 31b conveys the sheet 9 while sandwiching it between the second nip N2.

That is, the printing device 4 forms an image on the sheet 9 at the printing position P1 on the downstream side of the transport direction D1 from the position of the secondary roller pair 31b in the transport path 300.

Further, the sheet transfer device 3 includes a roller drive device 30 for individually rotating or stopping the primary roller pair 31a and the secondary roller pair 31b, respectively. For example, the roller drive device 30 includes a motor, a gear mechanism that transmits the rotational force of the motor to the primary roller pair 31a and the secondary roller pair 31b, and two corresponding to each of the primary roller pair 31a and the secondary roller pair 31b. Equipped with a clutch.

The two clutches are in a clutch-on state in which the driving force is transmitted from the gear mechanism to the primary roller pair 31a and the secondary roller pair 31b, respectively, and a clutch-off state in which the transmission of the driving force is cut off, according to the control by the transport control unit 8b. Selectively switch from one to the other.

The secondary roller pair 31b is a resist roller pair that adjusts the timing of transporting the sheet 9 toward the printing apparatus 4 by suspending the sheet 9.

As shown in FIG. 1, the image forming apparatus 10 further includes a sheet detecting apparatus 5. The sheet detection device 5 detects the sheet 9 at a predetermined detection position P2 between the primary roller pair 31a and the secondary roller pair 31b in the transport path 300.

In the following description, the tip end portion of the sheet 9 conveyed from the primary roller pair 31a to the secondary roller pair 31b is referred to as a sheet tip portion 90. The sheet detection device 5 can detect a sheet passing state in which the sheet tip 90 has passed the detection position P2.

As shown in FIG. 3, the seat detection device 5 includes a swing detection member 51 and a detection sensor 52. The swing detection member 51 has a rotating shaft 511, a contact piece 512, and a detected piece 513.

The rotating shaft 511 is rotatably supported by the frame of the main body 100. The contact piece 512 is formed so as to extend from the rotating shaft 511 to the detection position P2 along the radial direction of the rotating shaft 511. The detected piece 513 is formed so as to extend from the rotating shaft 511 to a region other than the transport path 300 along the radial direction of the rotating shaft 511.

The contact piece 512 is displaced from the upstream side to the downstream side in the transport direction D1 by coming into contact with the sheet tip portion 90 passing through the detection position P2. The detected piece 513 is displaced in conjunction with the displacement of the contact piece 512.

The detection sensor 52 is an object sensor that detects the detected piece 513 in a part of the displacement range of the detected piece 513. In this embodiment, the detection sensor 52 is a transmissive photo sensor. The detection sensor 52 may be a reflective photo sensor or a contact-type limit switch.

In the present embodiment, the change from the state in which the detection sensor 52 detects the detected piece 513 to the state in which the detection sensor 52 does not detect the detected piece 513 indicates the sheet passing state. The change from the state in which the detection sensor 52 does not detect the piece to be detected 513 to the state in which the detected piece 513 is detected may indicate the sheet passing state.

The transfer control unit 8b executes the first transfer control and the second transfer control, which are the controls of the roller drive device 30, each time one sheet 9 is sent out to the transfer path 300.

The first transfer control is a control for rotating the primary roller pair 31a with the secondary roller pair 31b stopped. As a result, the sheet 9 is conveyed toward the secondary roller pair 31b via the primary roller pair 31a.

The first transfer control is continued until a predetermined monitoring time elapses after the sheet passing state is detected by the sheet detecting device 5. The monitoring time is set in advance based on the time required for the sheet tip 90 to move from the detection position P2 to the secondary roller pair 31b by transporting the sheet 9 by the primary roller pair 31a.

When the first transfer control is executed, the sheet tip 90 reaches the secondary roller pair 31b, the sheet 9 is further bent, and the sheet tip 90 is along the secondary roller pair 31b. That is, the first transfer control is a skew correction control in which the tip of the sheet 9 is aligned with the secondary roller pair 31b while forming a deflection in the sheet 9.

When the first transfer control is being performed, the secondary roller pair 31b contacts the sheet tip 90 of the sheet 9 transported from the primary roller pair 31a with the second nip N2 in a state where the rotation is stopped. By making the sheet 9 bend in a predetermined direction, the sheet 9 is skew-corrected by aligning the sheet tip 90 with the second nip N2.

The deflection forming region 300a shown in FIG. 5 is a region that allows the sheet 9 to bend in the transport path 300. The deflection forming region 300a is a region on the upstream side in the transport direction D1 with respect to the secondary roller pair 31b and on the downstream side in the transport direction D1 with respect to the primary roller pair 31a.

The second transfer control is executed after the monitoring time has elapsed after the sheet passing state is detected by the sheet detecting device 5. The second transfer control includes at least a control for rotating the secondary roller vs. 31b.

For example, it is conceivable that the second transfer control is a control for rotating the secondary roller vs. 31b while continuing the rotation of the primary roller vs. 31a.

It is also conceivable that the second transfer control is a control in which the primary roller pair 31a is temporarily stopped and then the primary roller pair 31a and the secondary roller pair 31b are rotated simultaneously or in a predetermined order. ..

It is also conceivable that the second transfer control is a control in which the primary roller pair 31a is temporarily stopped and then the secondary roller pair 31b is rotated without driving the primary roller pair 31a. In this case, the primary roller pair 31a is driven to rotate in response to the movement of the sheet 9 conveyed by the secondary roller pair 31b.

FIG. 4 shows the sheet passing state in which the sheet tip 90 passes through the detection position P2 under the condition that the sheet 9 is conveyed in the oblique state. In the following description, of the left and right edge portions of the sheet tip portion 90, the preceding one is referred to as a first edge portion 90a, and the following other edge portion is referred to as a second edge portion 90b.

When the first transfer control is executed, the primary roller pair 31a comes into contact with the secondary roller pair 31b at which the first edge portion 90a of the seat tip portion 90 is stopped, and further, the second edge of the seat tip portion 90. The portion 90b rotates until it comes into contact with the stopped secondary roller pair 31b.

Therefore, in a situation where the first edge portion 90a of the sheet tip portion 90 is in contact with the secondary roller pair 31b, the primary roller pair 31a hits the secondary roller pair 31b with the second edge portion 90b of the sheet tip portion 90. Rotate until it touches. As a result, the sheet 9 bends mainly on the side of the first edge portion 90a, and the entire sheet tip portion 90 is in a state of being along the secondary roller pair 31b.

After that, when the second transfer control is executed, the secondary roller pair 31b starts transferring the sheet 9 to the printing device 4 with the sheet tip 90 along the width direction D2. As a result, the skew of the sheet 9 is corrected.

By the way, when the sheet 9 is oblique, the preceding first edge portion 90a of the left and right edge portions of the sheet tip portion 90 comes into contact with the secondary roller pair 31b, and then the subsequent second edge portion 90b is two. The sheet 9 bends by the time it reaches the next roller pair 31b.

Deflection of the sheet 9 may occur not only in the portion of the sheet 9 on the first edge portion 90a side but also in the portion on the second edge portion 90b side. In this case, the time difference between the first edge portion 90a and the second edge portion 90b reaching the secondary roller pair 31b becomes large.

When the time difference may be large, it is necessary to increase the time of the first transfer control, that is, the time of skew correction transfer. However, if the time of the first transfer control is long, the sheet 9 may be significantly damaged due to the large bending of the sheet 9.

The image forming apparatus 10 includes a configuration for correcting the skew of the sheet 9 while suppressing damage to the sheet 9. The configuration will be described below.

As shown in FIG. 5, the image forming apparatus 10 further includes a swing guide member 6 arranged in a deflection forming region 300a between the primary roller pair 31a and the secondary roller pair 31b in the transport path 300.

As shown in FIG. 5, the region between the primary roller pair 31a and the secondary roller pair 31b in the transport path 300 is between the first seat guide portion 32 and the second seat guide portion 33 arranged so as to face each other. Area of. The first seat guide unit 32 and the second seat guide unit 33 guide the seat 9 sent out from the primary roller pair 31a to the secondary roller pair 31b.

As shown in FIGS. 6 and 7, the swing guide member 6 is formed so as to extend in the width direction D2 on both sides with respect to the width center portion 61 facing the center of the width direction D2 in the transport path 300. The swing guide member 6 is formed symmetrically with respect to the width central portion 61.

The width central portion 61 of the swing guide member 6 has a shaft portion 61a protruding along the transport direction D1. The shaft portion 61a is provided at the center of the width direction D2 in the transport path 300 and is formed so as to extend in the transport direction D2. The swing guide member 6 is formed so as to extend in the width direction D2 on both sides with respect to the shaft portion 61a. The shaft portion 61a is an example of a swing shaft.

The swing guide member 6 has a pair of arm portions 62 connected to the width central portion 61 and a pair of seat holding portions 63 connected to the pair of arm portions 62.

The pair of arm portions 62 are formed so as to extend from the width central portion 61 to both the left and right sides along the width direction D2. In the present embodiment, the pair of arm portions 62 are formed so as to extend from the shaft portion 61a to both the left and right sides along the width direction D2.

The pair of seat holding portions 63 are formed so as to extend further outward from the pair of arm portions 62. The pair of arm portions 62 and the pair of seat restraining portions 63 are formed symmetrically with respect to the width center portion 61. The pair of seat holding portions 63 have a curved surface 63a that is convex toward the transport path 300 side when viewed from the width direction D2 (see FIGS. 5 and 7).

The shaft portion 61a is rotatably supported by the frame of the main body 100 or the second seat guide portion 33. As a result, the swing guide member 6 is supported so as to be swingable around the center width portion 61.

The pair of seat holding portions 63 are portions that come into contact with one side of the sheet 9 that passes through the transport path 300. The swing guide member 6 is arranged so as to face the transport path 300 from the convex side, which is the side where the seat 9 is convexly curved in the transport path 300.

As shown in FIG. 5, the convex side is on both sides of the first plane F1 passing through the first nip N1 in which the primary roller pairs 31a are in contact with each other and the second nip N2 in which the secondary roller pairs 31b are in contact with each other. , A side of the second plane F2 orthogonal to the plane passing through both rotation center lines of the primary roller pair 31a and passing through the first nip N1 where a portion downstream of the first nip N1 in the transport direction D1 exists.

As described above, when the sheet 9 is oblique, the preceding first edge portion 90a at the sheet tip portion 90 comes into contact with the secondary roller pair 31b, and then the subsequent second edge portion 90b is the secondary roller pair. The sheet 9 bends by the time it reaches 31b. The swing guide member 6 limits the bending of the seat 9 by abutting on the bent portion of the seat 9.

As shown in FIG. 8, when the seat 9 is bent at the portion of the seat 9 on the first edge portion 90a side, one of the pair of seat holding portions 63 of the swing guide member 6 is a curved seat 9. It is pushed by the portion on the side of the first edge portion 90a and is displaced in the direction of expanding the transport path 300. As a result, the other of the pair of seat holding portions 63 is displaced in the direction of narrowing the transport path 300.

Therefore, the sheet holding portion 63 that narrows the transport path 300 prevents the portion of the sheet 9 on the second edge portion 90b side from bending. As a result, it is possible to prevent the time difference between the first edge portion 90a and the second edge portion 90b from reaching the secondary roller pair 31b from becoming large.

Since the time difference does not become large, the time of the first transfer control can be set to the minimum necessary. As a result, it is prevented that the sheet 9 is damaged due to the large bending of the sheet 9.

As shown in FIG. 5, the central portion 64 of the transport direction D1 in the swing guide member 6 is an intermediate portion that bisects the range from the position of the primary roller pair 31a to the position of the secondary roller pair 31b in the transport direction D1. It is located upstream of the position P3 in the transport direction D1. This makes it possible to more effectively prevent the sheet 9 from bending significantly.

Further, as shown in FIGS. 7 and 8, the image forming apparatus 6 includes a limiting portion 71 that limits the swing range of the swing guide member 6. This prevents the rocking guide member 6 from swinging excessively.

Further, as shown in FIGS. 7 and 8, the image forming apparatus 6 further includes an elastic member 72 that elastically biases the swing guide member 6. The elastic member 72 elastically biases the swing guide member 6 in the direction of returning to the reference posture when the swing guide member 6 swings from a predetermined reference posture.

In the example shown in FIGS. 7 and 8, the elastic member 72 is a flexible film member whose one end is cantilevered and supported so as to project toward the swing guide member 6. By providing the elastic member 72, the posture of the swing guide member 6 is stabilized.

1: Sheet accommodating unit 2: Sheet delivery device 3: Sheet transfer device 4: Printing device 5: Sheet detection device 6: Swing guide member 8: Control device 8a: Main control unit 8b: Transfer control unit 8c: Print control unit 9 : Sheet 10: Image forming apparatus 30: Roller driving device 31: Conveying roller pair 31a: Primary roller pair 31b: Secondary roller pair 32: First sheet guide unit 33: Second sheet guide unit 40: Optical scanning unit 41: Photosensitive Body 42: Charging device 43: Developing device 45: Transfer device 46: Cleaning device 47: Fixing device 51: Swing detection member 52: Detection sensor 61: Width center portion 61a: Shaft portion 62: Arm portion 63: Seat holding portion 81 : CPU
82: RAM
83: Secondary storage device 84: Signal interface 90: Sheet tip 90a: First edge 90b: Second edge 100: Main body 101: Paper discharge tray 300: Transport path 511: Rotating shaft 512: Contact piece 513: Covered Detection piece D1: Conveyance direction D2: Width direction F1: First plane F2: Second plane N1: First nip N2: Second nip

Claims (4)

A pair of primary rollers arranged in a sheet transport path, forming a first nip, and transporting the sheet while sandwiching the sheet in the first nip by rotating.
The tip of the sheet, which is arranged on the downstream side in the sheet transport direction from the position of the primary roller pair in the sheet transport path, forms the second nip, and is transported from the primary roller pair in a state where the rotation is stopped. By abutting on the second nip, the sheet is formed to bend in a predetermined direction, and by aligning the tip of the sheet along the second nip, skew correction of the sheet is performed, and by rotating, the sheet is said. A secondary roller pair that takes over from the primary roller pair and conveys the sheet, and
A printed portion that forms an image on the sheet at a position downstream of the position of the secondary roller pair in the sheet transport path in the sheet transport direction.
The secondary roller pair in the sheet transport path is swingably supported by a flexure forming region that allows the sheet to bend on the upstream side in the sheet transport direction, and abuts on the flexed portion of the sheet. A swing guide member for limiting the bending of the seat is provided.
The swing guide member is provided at the center of the seat transport path in the width direction and is formed so as to extend in the width direction on both sides with respect to the swing shaft extending in the seat transport direction, and swings around the swing shaft. An image forming apparatus that is movably supported. The rocking guide member is
A pair of arm portions formed so as to extend from the swing axis to the left and right sides along the width direction,
It has a pair of seat holding portions that are formed from the pair of arm portions and further extend outward in the width direction and come into contact with the seat.
The image forming apparatus according to claim 1, wherein the pair of sheet holding portions have a curved surface having a convex shape toward the sheet transport path side when viewed from the width direction. The rocking guide member includes both of the primary roller pair on both sides of the first plane through which the primary roller pair is in contact with each other and the second nip in which the secondary roller pair is in contact with each other. It is arranged so as to face the sheet transport path from the side where the portion downstream of the first nip in the second plane passing through the first nip, which is orthogonal to the plane passing through the rotation center line, exists. The image forming apparatus according to claim 1. The central portion of the rocking guide member in the sheet transport direction is in the sheet transport direction rather than the position that bisects the range from the position of the primary roller pair to the position of the secondary roller pair in the sheet transport direction. The image forming apparatus according to claim 1 or 2, which is located on the upstream side.

Images