Sheet loading device and image formation device

Abstract

To allow for better conformity to be achieved for a wider variety of sheets.SOLUTION: A sheet loading device comprises: a loading section; transporting means for transporting a sheet; an abutment section against which a leading edge of the sheet abuts; a first retraction member for pulling in the sheet transported by the transporting means in a sheet transport direction and abutting it against the abutment section; and a second retraction member for pulling in the sheet transported by the transporting means in the sheet transport direction and abutting it against the abutment section, the second retraction member provided so as to be switchable between a contact state in which it contacts the sheets loaded on the loading section and a retracted state in which it is retracted from the sheets loaded on the loading section; and control means capable of executing a first mode in which the second retraction member is in a contact state and the sheet is pulled in by the first retraction member and the second retraction member, and a second mode in which the second retraction member is in a retracted state and the sheet is pulled in by the first retraction member.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a sheet stacking device that stacks sheets, and an image forming apparatus that forms an image on a sheet. [Background technology]

[0002] In an image forming apparatus, a sheet stacking device such as a large-capacity stacker that stacks sheets on which images are formed is used. Patent Document 1 describes a sheet stacking device in which a gripper supported by a timing belt grips and conveys a sheet, and then a knurled belt abuts the leading edge of the sheet against a stopper to align the sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-168218 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for a sheet stacking device and an image forming apparatus capable of handling a variety of sheets as recording materials. However, in the configuration of the above document, even if the conveying force applied to the sheet by the knurled belt is adjusted, there are cases where the sheet alignment is poor due to insufficient conveying force, or the sheet alignment is poor due to bending or buckling caused by excessive conveying force.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a sheet stacking device and an image forming apparatus that are capable of achieving good alignment for a wider variety of sheets. [Means for solving the problem]

[0006] One aspect of the present invention is a sheet loading device comprising: a loading section on which sheets are loaded; a transport means for transporting the sheets in a sheet transport direction toward the loading section; a stop section against which the leading edge of the sheet in the sheet transport direction is abutted; a first retraction member for pulling the sheet transported by the transport means in the sheet transport direction and abutting it against the abutment section; and a second retraction member for pulling the sheet transported by the transport means in the sheet transport direction and abutting it against the abutment section, the second retraction member being switchable between a contact state in which it contacts the sheets loaded on the loading section and a retracted state in which it is retracted from the sheets loaded on the loading section; and control means capable of executing a first mode in which the second retraction member is in the contact state and the sheets are pulled in by the first retraction member and the second retraction member, and a second mode in which the second retraction member is in the retracted state and the sheets are pulled in by the first retraction member. Effect of the Invention

[0007] According to the present invention, it is possible to provide a sheet stacking device and an image forming apparatus that are capable of achieving good alignment for a wider variety of sheets. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing a control unit of the image forming apparatus according to the embodiment. [Diagram 3] FIG. 1 is a schematic diagram of a stacker according to an embodiment. [Figure 4] 2A to 2C are diagrams showing a stack section of a stacker according to an embodiment. [Diagram 5] 2A to 2D are diagrams showing a stacker according to an embodiment. [Figure 6] 6 is a flowchart showing an example of control of a sheet stacking operation according to the embodiment. [Figure 7] 4 is a table showing the correspondence between seat information and whether or not the assist belt needs to be inserted in the embodiment; [Figure 8]6A and 6B are diagrams for explaining a tapered portion of a tip abutment surface. [Figure 9] 1A to 1C are diagrams for explaining a stacker of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0010] 1 is a schematic diagram showing an image forming apparatus 1S according to one embodiment. The image forming apparatus 1S includes an image forming apparatus main body 1 (printer unit) that forms an image on a sheet P, and a stacker 100 as a sheet stacking device that receives and stacks the sheet P on which the image has been formed from the image forming apparatus main body 1. As the sheet P which is the recording material (recording medium), various sheet materials of different sizes and materials can be used, including paper such as plain paper and cardboard, sheet materials with a surface treatment such as coated paper, sheet materials with special shapes such as envelopes and index paper, plastic films, cloth, etc.

[0011] The image forming apparatus main body 1 is a color image forming apparatus using an electrophotographic method. The image forming apparatus main body 1 is equipped with an intermediate transfer tandem type image forming section 1B in which process sections PY, PM, PC, and PK (process units, image forming stations) that create four-color toner images are arranged along an intermediate transfer belt 31. The intermediate transfer tandem type has the advantages of being adaptable to a wide variety of sheets P and excellent print productivity.

[0012] The image forming apparatus 1S is an image forming system including an image forming apparatus main body 1 and a stacker 100 as a sheet stacking device. The image forming apparatus 1S may include devices other than the image forming apparatus main body 1 and the stacker 100. Such devices include a sheet feeding device (optional feeder) that supplies sheets P to the image forming apparatus main body 1, and a sheet processing device (finisher) that performs processing such as binding on the sheets P.

[0013] (Image forming device body) The following describes the configuration of the image forming apparatus main body 1. The image forming apparatus main body 1 includes an image forming section 1B, a fixing device 5, storages 61-63, a manual feed tray 64, a conveyance guide forming a conveyance path for the sheet P and various roller pairs for conveying the sheet P, and a control section 200.

[0014] The image forming unit 1B includes four process units PY, PM, PC, and PK, an intermediate transfer belt 31, and a secondary transfer roller 41. Each process unit PY includes a photosensitive drum 11 as an image carrier, a charging device 12, an exposure device 13, a developing device 14, a primary transfer device 35, and a cleaning device 15. Each developing device 14 contains one of yellow, magenta, cyan, and black toner as a developer. However, the number of toner colors is not limited to four, and the order of the colors is not limited to this. The intermediate transfer belt 31 is stretched around a drive roller 33, a tension roller 34, and a secondary transfer inner roller 32, and is driven to rotate by the rotation of the drive roller 33. The secondary transfer roller 41 is in contact with the secondary transfer inner roller 32 with the intermediate transfer belt 31 sandwiched therebetween. A secondary transfer unit is formed as a nip between the secondary transfer roller 41 and the intermediate transfer belt 31, as a transfer unit where a toner image is transferred to the sheet P.

[0015] The image forming operation is as follows: In the image forming operation, each process unit PY, PM, PC, and PK forms a monochrome toner image of yellow, magenta, cyan, and black, respectively, on the photosensitive drum 11, and the monochrome toner images are superimposed on the intermediate transfer belt 31 to form a full-color image.

[0016] In each of the process units PY, PM, PC, and PK, the photosensitive drum 11 is rotated, and the charging device 12 uniformly charges the surface of the photosensitive drum 11. The exposure device 13 exposes the photosensitive drum 11 by irradiating it with light based on a signal received from the control unit 200, and forms an electrostatic latent image on the surface of the photosensitive drum 11. The developing device 14 supplies toner to the photosensitive drum 11 and develops the electrostatic latent image into a toner image. The primary transfer device 35 primarily transfers the toner image carried on the photosensitive drum 11 to the intermediate transfer belt 31. Residual toner remaining on the photosensitive drum 11 without being transferred to the intermediate transfer belt 31 is collected by the cleaning device 15.

[0017] The single-color toner images created in each process unit PY, PM, PC, and PK are primarily transferred onto the intermediate transfer belt 31 at timing adjusted so that they are superimposed on each other on the intermediate transfer belt 31. As a result, a full-color image is formed on the intermediate transfer belt 31. This full-color image is transported to the secondary transfer unit by the rotation of the intermediate transfer belt 31.

[0018] In parallel with the creation of the toner image in the image forming unit 1B, the sheet P is conveyed. The sheets P are stacked in the storages 61, 62, 63 or the manual feed tray 64, and are fed one by one by the feeding units 61a, 62a, 63a, 64a. The fed sheet P is conveyed along the feeding path 73 by the conveying roller pairs 70, 71, 72, 74, 75, and reaches the registration roller pair 76. The registration roller pair 76 stops the leading edge of the sheet P to correct the skew, and then conveys the sheet P to the secondary transfer unit in time with the full-color image reaching the secondary transfer unit. Then, in the secondary transfer unit, the full-color image is secondarily transferred from the intermediate transfer belt 31 to the sheet P by the secondary transfer roller 41.

[0019] Thereafter, the sheet P is transported to the fixing device 5 by the pre-fixing transport unit 42. The pre-fixing transport unit 42 transports the sheet P by rotating the belt while attracting the sheet P to the belt by generating negative pressure, for example, by a fan. The fixing device 5 is a thermal fixing type unit having a pair of rotating bodies made of rollers or belts, and a heating means for heating the image on the sheet P. As the heating means, a halogen lamp or an induction heating mechanism can be used. The fixing device 5 fixes the image on the sheet P by applying heat and pressure to the toner on the sheet P while nipping and transporting the sheet P at the nip portion (fixing nip) of the pair of rotating bodies.

[0020] The conveying path of the sheet P that has passed through the fixing device 5 is switched by a switching guide 81. In the case of single-sided printing (single-sided image formation), the sheet P is guided to a discharge path 82 by the switching guide 81, and is discharged from the image forming apparatus main body 1 by a discharge roller pair 77. In the case of double-sided printing (double-sided image formation), the sheet P with an image formed on the first side is guided to a reversing path 83 by the switching guide 81, and is conveyed to a switchback path 84 via a conveying roller pair 79. The sheet P that has been switched back by the reversing roller pairs 86 and 87 is conveyed again to the registration roller pair 76 via a double-sided path 85. Then, the sheet P with an image formed on the second side by passing through the secondary transfer unit and the fixing device 5 again is guided to a discharge path 82 by the switching guide 81, and is discharged from the image forming apparatus main body 1 by a discharge roller pair 77.

[0021] In addition, in the case of single-sided printing, the image forming apparatus main body 1 can perform so-called face-down discharge, in which the sheet P on which an image has been formed is discharged with the surface facing down. In this case, the sheet P that has passed through the fixing device 5 is guided to a reversing path 83, switched back by a switchback path 84, and then conveyed to a discharge roller pair 77 via a second discharge path 78.

[0022] Moreover, the intermediate transfer tandem type image forming unit 1B described in this embodiment is an example of an image forming means that forms an image on a sheet P. The image forming means may be, for example, a direct transfer type electrophotographic unit that transfers a toner image directly from an image carrier to a sheet without using an intermediate transfer body, an inkjet type printing unit, or an offset type printing unit.

[0023] (Explanation of the control unit) 2 is a block diagram showing the configuration of the control unit 200. The control unit 200 has a CPU circuit unit 206. The CPU circuit unit 206 incorporates a CPU 203, a ROM 207, and a RAM 208. The CPU circuit unit 206 comprehensively controls an operation unit 209, an image signal control unit 204, a printer control unit 205, a stacker control unit 210, etc., by the CPU 203 reading and executing a control program stored in the ROM 207.

[0024] The control unit 200 also includes an external I / F 201 which is an interface between the image forming apparatus main body 1 and an external computer 211. The external I / F 201 expands image information (print data) received from the computer 211 into a bitmap image and outputs it to the image signal control unit 204 as image data (digital image signal). The RAM 208 temporarily holds control data and is used as a work area for arithmetic processing associated with control. The image signal control unit 204 performs various processes on the image data input from the computer 211 via the external I / F 201, and converts the image data into a video signal and outputs it to the printer control unit 205. The processing by the image signal control unit 204 is controlled by a CPU circuit unit 206. The printer control unit 205 drives the above-mentioned exposure device 13 via an exposure control unit (not shown) based on the input video signal.

[0025] The operation unit 209 has an input unit such as a plurality of keys or a touch panel for setting various functions related to image formation, and a display unit (display panel, lamps, etc.) for displaying information indicating the setting state, etc. The operation unit 209 outputs a signal corresponding to the operation of the input unit to the CPU circuit unit 206, and displays information on the display unit based on a signal from the CPU circuit unit 206. A user can set information indicating attributes of a sheet P on which an image is formed by the image forming apparatus 1S (hereinafter, sheet information) by operating the operation unit. The sheet information in this embodiment is any one of the basis weight, size, and material of the sheet P, or a combination of these. The material of the sheet P is, for example, a classification such as coated paper, plain paper, recycled paper, etc.

[0026] The stacker control unit 210 is mounted on the stacker 100 (FIG. 1). The stacker control unit 210 controls the operation of the entire stacker 100 including a belt drive motor 310, a belt lifting motor 311, a sheet detection unit 312, and the like, which are mounted on the stacker 100 and described below, by exchanging information with the CPU circuit unit 206. The stacker control unit 210 is an example of a control means for controlling the operation of the sheet loading device. The control unit 200 and the stacker control unit 210 of the image forming apparatus main body 1 are an example of a control means for the entire system for controlling the operation of the image forming apparatus 1S. Note that some or all of the functions of the stacker control unit 210 described below may be incorporated into the CPU circuit unit 206 of the image forming apparatus main body 1, so that the stacker 100 is controlled directly from the image forming apparatus main body 1.

[0027] (Overall stacker description) The stacker 100 will be described with reference to Fig. 3. The stacker 100 has an inlet roller pair 101, a first switching member 102, a second switching member 121, a conveying path 103, an outlet roller pair 104, and a sample tray 109. The stacker 100 also has a discharge roller pair 105, a stacking tray 106, grippers 107a and 107b, a gripper belt 108, a leading end stopper 114, a retraction belt 116a, an assist belt 116b, and a side end regulating member. The leading end stopper 114 has a contact inclined surface 114a and a leading end abutment surface 114b.

[0028] The stacking tray 106 is an example of a stacking section on which the sheets P are stacked. The discharge roller pair 105, the grippers 107a and 107b, and the gripper belt 108 are examples of a conveying means for conveying the sheets P toward the stacking section. The leading end abutting surface 114b of the leading end stopper 114 is an example of an abutting section against which the leading end of the sheet P in the sheet conveying direction D1 (the downstream end of the sheet P in the sheet conveying direction D1) abuts.

[0029] The entrance roller pair 101 receives and transports the sheet P discharged from the image forming apparatus main body 1. The first switching member 102 switches the transport path of the sheet P sent out from the entrance roller pair 101 between a transport path toward the exit roller pair 104 or the sample tray 109 and a transport path (loading path) toward the stacking tray 106. The second switching member 121 switches the transport path of the sheet P between a transport path 103 toward the exit roller pair 104 and a transport path toward the sample tray 109. The exit roller pair 104 discharges the sheet P transported on the transport path 103 to the outside of the stacker 100.

[0030] The discharge roller pair 105 conveys the sheet P in a sheet conveying direction D1 and discharges it toward the stacking tray 106. The gripper belt 108 (timing belt) is disposed above the stacking tray 106, and is stretched around a driving pulley 111 and a driven pulley 112. The gripper belt 108 is rotationally driven in a rotation direction along the sheet conveying direction D1 by the rotation of the driving pulley 111 driven by a belt motor. The grippers 107a and 107b are attached to predetermined positions in the circumferential direction of the gripper belt 108, respectively, and rotate together with the gripper belt 108. The grippers 107a and 107b are configured to be movable in the sheet conveying direction D1 while gripping (sandwiching) the leading edge of the sheet P discharged from the discharge roller pair 105.

[0031] The stacking tray 106 is provided so as to be movable up and down inside the stacker 100. The stacking tray 106 is controlled to be lifted and lowered in accordance with the amount of stacked sheets so that the upper surface of the sheets P stacked on the stacking tray 106 is maintained at a substantially constant height based on the detection result of a sheet upper surface sensor that detects the sheets P at a predetermined height above the stacking tray 106, for example.

[0032] The leading edge stopper 114 is disposed at the downstream end in the sheet conveying direction D1 of the stacking space on the stacking tray 106. The contact slope 114a of the leading edge stopper 114 protrudes downward from the lower surface of the gripper belt 108, and the leading edge abutment surface 114b is provided further downward than the contact slope 114a.

[0033] The contact inclined surface 114a is a surface that comes into contact with the leading edge of the sheet P gripped by the gripper 107a or 107b to separate the sheet P from the gripper 107a or 107b. In this embodiment, the contact inclined surface 114a is an inclined surface that slopes downward toward the downstream side in the sheet conveying direction D1. The leading edge abutting surface 114b is a surface that expands in the vertical direction. The leading edge of the sheet P abuts against the leading edge abutting surface 114b, so that the position of the sheet P stacked on the stacking tray 106 in the sheet conveying direction D1 is aligned. In other words, the leading edge abutting surface 114b serves as an alignment reference for the sheet P stacked on the stacking tray 106 in the sheet conveying direction D1.

[0034] The retraction belt 116a is disposed above the stacking tray 106, downstream of the upstream end of the contact slope 114a and upstream of the leading end abutment surface 114b in the sheet conveying direction D1. The retraction belt 116a is an example of a first retraction member that retracts the sheet P in the sheet conveying direction D1 and abuts against the abutment portion.

[0035] The assist belt 116b is an example of a second pull-in member that cooperates with the pull-in belt 116a to pull the sheet P in the sheet transport direction D1 and abuts against the abutment portion. The assist belt 116b will be described in detail later.

[0036] The pull-in belt 116a is formed endlessly from an elastic material such as silicone rubber, EPDM (ethylene propylene rubber), or urethane rubber. The pull-in belt 116a is arranged so as to come into contact with the upper surface of the sheets P stacked on the stacking tray 106 and be in an elastically deformed state. In other words, the lower end position of the pull-in belt 116a when the stacking tray 106 and the sheet stack on the stacking tray 106 are retracted downward from the pull-in belt 116a is intruding downward with respect to the upper surface position of the sheet stack on the stacking tray 106 during the sheet stacking operation. Due to the elasticity of the pull-in belt 116a, the contact pressure when the outer circumferential surface of the pull-in belt 116a comes into contact with the upper surface of the sheet stack on the stacking tray 106 becomes appropriate.

[0037] The lead-in belt 116a is also called an alignment belt that aligns the sheet P. The lead-in belt 116a may be a knurled belt that is knurled (roughened) to adjust the frictional force against the sheet P.

[0038] The side end regulating members are regulating members that regulate the position in the sheet width direction of the sheet P loaded on the stacking tray 106. The sheet width direction is a direction perpendicular to the sheet conveying direction D1 (the depth direction of the paper in FIG. 3). The side end regulating members of this embodiment are a pair of regulating members that are movable in the sheet width direction between a regulating position that regulates the side end position of the sheet P and a retracted position (sheet receiving position) that is retracted outward from the regulating position in the sheet width direction. The regulating position is set in advance corresponding to the length (sheet width) of the sheet P in the sheet width direction.

[0039] 2, the stacker 100 includes a belt drive motor 310 as a drive source for rotating the retraction belt 116a and the assist belt 116b, and a sheet detection unit 312 for detecting the sheet P. Furthermore, the stacker 100 includes a belt lift motor 311 for switching the assist belt 116b between a contact state (intrusion state) and a retracted state.

[0040] The sheet detection unit 312 includes a plurality of sensors each capable of detecting a sheet. Each sensor is arranged at a predetermined position (detection position) on a conveyance path in the stacker 100, and may be an optical sensor that detects the presence or absence of the sheet P at the detection position using light. The sheet detection unit 312 also includes the above-mentioned sheet upper surface sensor. The stacker control unit 210 can obtain information such as the current position of the sheet P in the stacker 100 and the amount of sheets stacked on the stacking tray 106 based on the detection signal from each sensor of the sheet detection unit 312.

[0041] (Stacker operation) The operation of the stacker 100 will be described with reference to FIG. 3. When a sheet P is discharged from the image forming apparatus main body 1, an entrance roller pair 101 receives the sheet P. The sheet P is guided by a first switching member 102 and a second switching member 121 to a predetermined transport path according to a job setting previously set by an operation unit 209 or the like. When the job setting specifies that the loading location of the sheet P is a device (such as a sheet processing device) connected downstream of the stacker 100, the sheet P passes through a transport path 103 and is discharged by an exit roller pair 104. When the job setting specifies that the loading location of the sheet P is a sample tray 109, the sheet P is discharged to the sample tray 109.

[0042] When the stacking location of the sheet P is specified to be the stacking tray 106 in the job settings, the stacker 100 executes the following sheet stacking operation (stacking process). First, the sheet P sent out from the pair of inlet rollers 101 is guided to the pair of discharge rollers 105 by the first switching member 102. The rotation of the gripper belt 108 is controlled so as to be synchronized with the timing at which the sheet P is sent out from the pair of discharge rollers 105, and the leading edge of the sheet P sent out from the pair of discharge rollers 105 is gripped by one of the two grippers 107a and 107b. The case where the sheet P is gripped by the gripper 107a will be described below.

[0043] The sheet P is held by the discharge roller pair 105 and the gripper 107a and is transported in the sheet transport direction D1 above the stack tray 106. Then, when the leading edge of the sheet P abuts against the contact slope 114a of the leading edge stopper 114, the leading edge of the sheet P is released from the gripper 107a and moves along the contact slope 114a toward the retraction belt 116a and the assist belt 116b.

[0044] Here, the distance from the nip position of the discharge roller pair 105 in the sheet conveying direction D1 to the contact position of the pull-in belt 116a is shorter than the sheet length of the sheet P loaded on the stacking tray 106. The contact position is the center position of the contact area between the pull-in belt 116a and the sheet P. The leading end stopper 114 and the pull-in belt 116a are moved in advance to positions corresponding to the length of the sheet P loaded on the stacking tray 106 along the sheet conveying direction D1 (hereinafter simply referred to as the sheet length) based on the job setting. In addition, the position of the stacking tray 106 when the sheet P is discharged onto the stacking tray 106 (loading position) is controlled to a height at which the pull-in belt 116a contacts the upper surface of the sheet stack on the stacking tray 106.

[0045] Therefore, after the leading edge of the sheet P is released from the gripper 107a, the leading edge of the sheet P comes into contact with the retraction belt 116a and receives a force (conveying force) in the sheet conveying direction D1 from the retraction belt 116a before the trailing edge of the sheet P passes through the pair of discharge rollers 105. The leading edge of the sheet P is abutted against the leading edge abutting surface 114b of the leading edge stopper 114 by the retraction belt 116a moving the sheet P in the sheet conveying direction D1. This aligns the position of the sheet P in the sheet conveying direction D1. If the sheet P is skewed, the leading edge is corrected by making the leading edge follow the leading edge abutting surface 114b. Also, before the leading edge of the sheet P abuts against the leading edge stopper 114, the trailing edge of the sheet P passes through the pair of discharge rollers 105.

[0046] The above operations are repeatedly performed when image forming apparatus 1S executes a job (continuous job) of continuously forming images on a plurality of sheets P and stacking them in stacker 100. When a user removes sheets P from stacker 100, stacker 100 is opened by operating operation unit 209 (or an open / close button provided on stacker 100). In this case, stacker control unit 210 (FIG. 2) receiving the user's operation lowers stacking tray 106 from the stacking position to a lower position where sheets P can be removed, and enables access to stacking tray 106 by unlocking the door, etc.

[0047] The side end regulating member is driven to move to the retracted position before the sheet P is discharged onto the stacking tray 106, and to move to the regulating position after the leading end of the sheet P abuts against the leading end abutment surface 114b of the leading end stopper 114. This maintains the alignment of the sheet bundle stacked on the stacking tray 106 in the sheet conveying direction D1 and the sheet width direction.

[0048] (In the case of retractable belt only) Here, a comparative example that does not include the assist belt 116b will be described. Figures 9(a) to (c) show the state of the sheet stacking operation in the stacker of the comparative example.

[0049] In the comparative example, the assist belt 116b is not provided, and the sheet P is abutted against the leading end abutment surface 114b of the leading end stopper 114 by the conveying force of the retraction belt 516 alone, as shown in FIG. 9(a). The magnitude of the conveying force applied to the sheet P by the retraction belt 516 can be adjusted, for example, by changing the contact pressure of the retraction belt 516 with respect to the sheet P. The change in the contact pressure can be realized by adjusting the intrusion amount of the retraction belt 516 with respect to the upper surface position of the sheet bundle in the sheet stacking operation. The intrusion amount is the protrusion amount of the lower end position of the retraction belt 516 in a state where the stacking tray 106 and the sheet bundle are lowered to a position where they do not contact the retraction belt 516 with respect to the upper surface position of the sheet bundle in the sheet stacking operation. However, in the comparative example, the magnitude of the conveying force applied to the sheet P by the retraction belt 516 cannot be changed according to the attribute of the sheet P.

[0050] For this reason, if the conveying force is set for a light-weight sheet P, as shown in Fig. 9(b), the conveying force may be insufficient for a heavy-weight sheet P, and the leading edge of the sheet P may not reach the leading edge abutting surface 114b, resulting in misalignment. Light-weight sheets P are, for example, sheets with a small size (area), sheets with a small basis weight, and sheets made of a material with a low density such as recycled paper. A specific example of a light-weight sheet P is a form.

[0051] Furthermore, when the conveying force is set according to a heavy sheet P, as shown in FIG. 9(c), the conveying force may be excessive for a light sheet P. In this case, the conveying force from the retraction belt 516 and the reaction force from the leading end abutting surface 114b may cause the sheet P to bend or buckle, which may result in a decrease in consistency. Lightweight sheets P often have low rigidity (Young's modulus), and are therefore prone to bending or buckling. Heavy weight sheets P are, for example, sheets with a large size (area), sheets with a large basis weight, and sheets made of a material with high density, such as coated paper. A specific example of a heavy weight sheet P is packaging paper.

[0052] Therefore, in this embodiment, in addition to the retractable belt 116a, the retractable assist belt 116b is used to obtain good conformity for a wider variety of sheets.

[0053] (Assist Belt) The assist belt 116b will be described with reference to Figs. 4(a)-(c) and Figs. 5(a)-(d). Fig. 4(a) is a perspective view showing the stack unit ST of the stacker 100. The stack unit ST is a unit including the retraction belt 116a, the assist belt 116b, and the leading end stopper 114. Figs. 4(b) and (c) are views of the stack unit ST as seen from the upstream side in the sheet conveying direction D1. Fig. 5(a) is a schematic view showing the stacker 100 as seen from above. Fig. 5(b) is a cross-sectional view taken along line AA in Fig. 5(a). Figs. 5(c) and (d) are cross-sectional views taken along line BB in Fig. 5(a).

[0054] As shown in FIG. 4(a), (b), and FIG. 5(a), the assist belt 116b is arranged side by side with the retraction belt 116a in the sheet width direction D2. In this embodiment, the retraction belts 116a are arranged at symmetrical positions, one on each side, with respect to the center C0 of the stacking tray 106 in the sheet width direction D2. The assist belts 116b are arranged at symmetrical positions, one on each side, with respect to the center C0 of the stacking tray 106 in the sheet width direction D2. When one retraction belt 116a is the first retraction member and one assist belt 116b is the second retraction member, the other retraction belt 116a is an example of a third retraction member, and the other assist belt 116b is an example of a fourth retraction member.

[0055] As shown in FIG. 5B, the retracting belt 116a is sandwiched between a pair of driving rollers 115a. The pair of driving rollers 115a is rotationally driven by a belt driving motor 310 (FIG. 2). Due to the rotation of the pair of driving rollers 115a, the retracting belt 116a is rotationally driven in a clockwise direction in the figure (a rotation direction in which the lower part of the retracting belt 116a moves from the upstream side to the downstream side in the sheet conveying direction D1). The inner peripheral surface of the retracting belt 116a is guided by a guide roller at a position different from the pair of driving rollers 115.

[0056] As shown in FIG. 5(c), the assist belt 116b is sandwiched between the driving roller pair 115b. The driving roller pair 115b is rotationally driven by the belt driving motor 310 (FIG. 2). The driving roller pair 115b is an example of a roller pair that sandwiches the second pulling member. Due to the rotation of the driving roller pair 115b, the assist belt 116b is rotationally driven in the clockwise direction in the figure (the rotation direction in which the lower part of the assist belt 116b moves from the upstream side to the downstream side in the sheet conveying direction D1). The inner peripheral surface of the assist belt 116b is guided by a guide roller at a position different from the driving roller pair 115.

[0057] 5(c) and (d), the driving roller pair 115b is configured to be movable up and down by the driving force of a belt lifting motor 311 (FIG. 2). When the driving roller pair 115b is in the position (upper position, standby position) shown in FIG. 5(c), the assist belt 116b retracts (separates) upward from the upper surface of the sheets P stacked on the stacking tray 106. When the driving roller pair 115b is in the position (lower position, operating position) shown in FIG. 5(d), the assist belt 116b contacts the upper surface of the sheets P stacked on the stacking tray 106. The belt lifting motor 311 is an example of a drive unit that drives the roller pair to move up and down relative to the stacking unit so as to switch the second retracting member between a contact state and a retracted state.

[0058] The state of the assist belt 116b when the drive roller pair 115b is located at the upper position (FIG. 5(c)) is the "retracted state" of the assist belt 116b. The state of the assist belt 116b when the drive roller pair 115b is located at the lower position (FIG. 5(d)) is the "contact state" of the assist belt 116b. In this manner, the assist belt 116b of this embodiment is provided so as to be switchable between the contact state and the retracted state. The contact state may be referred to as an intrusion state in which the assist belt 116b intrudes into the sheets on the stacking tray 106 by a predetermined intrusion amount.

[0059] 4(a) and (b), the assist belt 116b in the contact state protrudes below the downward surface 114c through an opening provided in the downward surface 114c of the leading end stopper 114. As shown in FIG. 4(c), the assist belt 116b in the retracted state retracts above the downward surface 114c of the leading end stopper 114. However, as long as the assist belt 116b is configured not to substantially apply a conveying force to the sheet P in the retracted state, a part of the assist belt 116b in the retracted state may be located below the downward surface 114c.

[0060] In this embodiment, the retraction belt 116a always protrudes below the downward surface 114c of the leading end stopper 114, and does not switch between the contact state and the retracted state. The intrusion amount of the retraction belt 116a into the sheets on the stacking tray 106 is set to be equal to the intrusion amount of the assist belt 116b in the contact state with the sheets on the stacking tray 106, for example.

[0061] The assist belts 116b are preferably disposed on the inside of the retraction belts 116a in the sheet width direction D2 (closer to the center C0 than the retraction belts 116a). This is to make it difficult for the sheet P to turn (slant) when the sheet P is retracted only by the retraction belts 116a with the assist belts 116b in the retracted state. In other words, when the sheet P is retracted only by the retraction belts 116a with the assist belts 116b in the retracted state, if there is a difference in the moving speed between the left and right sides of the sheet P due to a difference in circumferential length or a difference in friction coefficient between the retraction belts 116a, the sheet P may turn (slant). In this case, if the distance between the retraction belts 116a in the sheet width direction D2 is narrow, the sheet P is likely to turn (slant). Here, the distance between the retracting belts 116a in the sheet width direction D2 is wider when the assist belts 116b are arranged inside the retracting belts 116a than when the assist belts 116b are arranged outside the retracting belts 116a. Therefore, according to the arrangement of this embodiment, the turning (skewing) of the sheet P can be reduced.

[0062] In addition, it is preferable that the retraction belt 116a and the assist belt 116b are disposed inward in the sheet width direction D2 from the side end position of the sheet having the shortest sheet width among the sheets P that can be loaded on the loading tray 106 by the stacker 100. This makes it possible to retract the sheets using the retraction belt 116a and the assist belt 116b regardless of the type of sheets P loaded on the loading tray 106.

[0063] In this embodiment, the sheet contact area of ​​the retracting belt 116a in the sheet conveying direction D1 is substantially the same as the sheet contact area of ​​the assist belt 116b in the sheet conveying direction D1. The sheet contact area of ​​the retracting belt 116a is an area where the retracting belt 116a contacts the top sheet when the top surface of the sheet stack on the stacking tray 106 is maintained at a predetermined height in the sheet stacking operation. The sheet contact area of ​​the assist belt 116b is an area where the assist belt 116b in a contacting state contacts the top sheet when the top surface of the sheet stack on the stacking tray 106 is maintained at a predetermined height in the sheet stacking operation.

[0064] (Sheet stacking operation sequence) Next, the sequence of the sheet stacking operation will be described. Fig. 6 is a flowchart showing an example of the control of the sheet stacking operation in this embodiment. Each step in the following flowchart is executed by the stacker control unit 210 based on an instruction from the control unit 200 of the image forming apparatus main body 1, unless otherwise specified.

[0065] When an image formation job including a job setting for stacking sheets P on the stacking tray 6 is input to the image forming apparatus 1S, the stacker control unit 210 starts a sheet stacking operation based on an instruction from the control unit 200 of the image forming apparatus main body 1. Then, the stacker control unit 210 rotates the belt drive motor 310 to start rotating the pull-in belt 116a and the assist belt 116b (S1).

[0066] One sheet P (hereinafter, referred to as the current sheet P) is discharged from the image forming apparatus main body 1, and the current sheet P is conveyed by the discharge roller pair 105 toward the stacking tray 106. In the process of conveying the current sheet P, the position information of the sheet P is detected by the sheet detection unit 312 (S2). The sheet P is conveyed while being gripped by the gripper 107a or 107b attached to the gripper belt 108, and is released from the gripper 107a or 107b when the leading edge of the sheet P abuts against the abutment slope 14a of the leading edge stopper 114.

[0067] The stacker control unit 210 judges whether the assist belt 116b is in contact or in a retreat state (whether the assist belt 116b needs to enter) based on sheet information designated in advance when the job is input (S3). When it is judged that the assist belt 116b is in contact (S3: YES), the stacker control unit 210 moves the driving roller pair 115b to a lower position by the belt lifting motor 311, and puts the assist belt 116b in contact (S4). The timing of putting the assist belt 116b in contact is, for example, the timing when the sheet P abuts against the abutment slope 114a of the leading end stopper 114. In this case, the sheet P is pulled in by both the retraction belt 116a and the assist belt 116b, and abuts against the leading end abutment surface 114b of the leading end stopper 114 (S5, FIG. 5(d)).

[0068] When it is determined that the assist belt 116b is to be in the retracted state (S3: NO), the stacker control unit 210 keeps the driving roller pair 115b in the upper position and maintains the assist belt 116b in the retracted state. In this case, the sheet P is drawn in by the drawing belt 116a and abuts against the leading end abutment surface 114b of the leading end stopper 114 (S5, FIG. 5(c)).

[0069] If the current sheet P is not the last sheet in the sheet stacking operation (S6: NO), the stacker control unit 210 returns to S2 and repeatedly executes the same processes (S2 to S5) for each sheet. If the current sheet P is the last sheet in the sheet stacking operation (S6: YES), the stacker control unit 210 stops the rotational driving of the pull-in belt 116a and the assist belt 116b, and ends the sheet stacking operation (S7).

[0070] In this embodiment, the criteria for determining whether or not the assist belt 116b needs to enter in S3 are preset so that the assist belt 116b is in a contact state for a heavy sheet P and in a retracted state for a light sheet P. Specifically, the table shown in FIG. 7 is a table showing an example of a criterion for determining whether or not the assist belt 116b needs to enter in accordance with sheet information. Here, an example is shown in which the necessity for the assist belt 116b to enter is determined based on the size and basis weight of the sheet. In the figure, "◯" indicates a contact state and "×" indicates a retracted state.

[0071] 7 is an example, and the threshold value for whether or not to intrude may be changed depending on the specific configuration of the stacker 100 (for example, the material of the retraction belt 116a and the assist belt 116b, the friction coefficient with the sheet, and the contact pressure with the sheet P). Also, while an example in which the size and basis weight of the sheet are used as the sheet information is shown in FIG. 7, whether or not to intrude the assist belt 116b may be determined based on the material of the sheet or other attributes of the sheet.

[0072] In this manner, in this embodiment, the assist belt 116b is provided which can be switched between a contact state and a retracted state. The stacker control section 210 can execute a mode in which the sheet P is drawn in by both the retraction belt 116a and the assist belt 116b (S3: YES, S4), and a mode in which the sheet P is drawn in by only the retraction belt 116a (S3: NO). In other words, the control means of this embodiment can execute a first mode in which the second retraction member is in the contact state and the sheet is drawn in by the first retraction member and the second retraction member, and a second mode in which the second retraction member is in the retracted state and the sheet is drawn in by the first retraction member.

[0073] In this manner, in this embodiment, by selectively using the first mode and the second mode, good alignment can be achieved for a wider variety of sheets.

[0074] For example, for a heavy sheet, by bringing the assist belt 116b into contact (first mode), the sheet P can be more reliably brought into contact with the leading end abutment surface 114b even when the conveying force of the retraction belt 116a alone is insufficient. This reduces the possibility of misalignment. Also, for a light sheet, by bringing the assist belt 116b into a retracted state (second mode), it is possible to avoid excessive conveying force. This reduces the possibility of bending or buckling of the sheet P between the retraction belt 116a and the assist belt 116b and the leading end abutment surface 114b, and improves the alignment of the light sheet.

[0075] In this embodiment, the stacker control unit 210 judges whether or not the assist belt 116b needs to be inserted based on sheet information that is specified in advance when a job is input. In other words, the control unit of this embodiment determines whether to execute the first mode or the second mode based on sheet information related to the sheets to be loaded on the stacking unit. This makes it possible to execute an appropriate mode according to the sheet information.

[0076] 7, if the size of the sheets (e.g., A3) is the same, the assist belt 116b is in a contact state when the basis weight is large (350 gsm or more), and is in a retracted state when the basis weight is small (less than 350 gsm). In other words, the control means of this embodiment executes the first mode when a sheet of a first basis weight is loaded, and executes the second mode when a sheet of a second basis weight smaller than the first basis weight is loaded. This makes it possible to execute an appropriate mode depending on the difference in basis weight.

[0077] 7, if the basis weight of the sheets (e.g., 200-250 gsm) is the same, the assist belt 116b is in a contact state when the size is large (e.g., B3), and is in a retracted state when the size is small (e.g., B4). In other words, the control means of this embodiment executes the first mode when a sheet of a first size is loaded, and executes the second mode when a sheet of a second size, which is smaller in area than the first size, is loaded. This makes it possible to execute an appropriate mode depending on the difference in size.

[0078] In addition, in this embodiment, the assist belt 116b can be in a contact state when a sheet of a high density material (e.g., coated paper) is loaded, and in a retracted state when a sheet of a low density material (e.g., plain paper or recycled paper) is loaded. In other words, the control means of this embodiment executes the first mode when a sheet of a first material is loaded, and executes the second mode when a sheet of a second material having a lower density than the first material is loaded. This makes it possible to execute an appropriate mode depending on the difference in material.

[0079] (Tapered part of the tip contact surface) The positional relationship between the tapered portion provided on the tip abutment surface 114b, and the retraction belt 116a and assist belt 116b will be described.

[0080] 4(a), the leading end abutment surface 114b of the leading end stopper 114 has an alignment surface 114b1 that extends substantially perpendicular to the sheet conveying direction D1, and a tapered portion 114b2 (inclined surface) that is inclined with respect to the alignment surface 114b1. The alignment surface 114b1 is a first surface that extends in the sheet width direction D2. The tapered portion 114b2 is a second surface that is adjacent to the first surface on the outer side of the sheet width direction D2 and is inclined toward the downstream side of the sheet conveying direction D1 toward the outer side of the sheet width direction D2.

[0081] It is preferable that a boundary 114b3 between the alignment surface 114b1 and the tapered portion 114b2 is located outside the assist belt 116b and inside the pull-in belt 116a in the sheet width direction D2. The reason for this positional relationship will be described with reference to FIG.

[0082] Fig. 8 is a schematic diagram showing the retraction belt 116a and the assist belt 116b on the left side in Fig. 4, and a part of the leading end abutment surface 114b. As described above, the leading end abutment surface 114b in this embodiment includes an alignment surface 114b1 and a tapered portion 114b2. When aligning the sheet P, the sheet P rotates so that the leading end Pa of the sheet P follows the alignment surface 114b1 due to the conveying force in the sheet conveying direction D1 received from the retraction belt 116a and the assist belt 116b, thereby correcting the skew of the sheet P.

[0083] 8, in the case of a comparative example in which the leading end abutting surface 114b does not have a tapered portion, the leading end Pa' of the sheet P rotates around the outer end 114b4 of the alignment surface 114b1 as a fulcrum. In contrast, in this embodiment, as shown by a solid line, the leading end abutting surface 114b has a tapered portion, so the leading end Pa of the sheet P rotates around the boundary 114b3 between the alignment surface 114b1 and the tapered portion 114b2 as a fulcrum.

[0084] Therefore, when the inclination of the sheet P is the same, the position when the sheet P starts to turn in this embodiment is downstream in the sheet conveying direction D1 from the position when the sheet P starts to turn in the comparative example (difference Δ). As a result, as shown by the hatched area in the figure, the area where the assist belt 116b contacts the sheet P when the sheet P starts to turn can be made larger, making it easier to turn the sheet P. The assist belt 116b is usually in contact when a heavy sheet P is being conveyed, and by making the contact area larger, the conveying force can be transmitted to the sheet P more efficiently. In other words, according to the position of the boundary 114b3 between the alignment surface 114b1 and the tapered portion 114b2 in this embodiment, it is easier to correct the skew of the sheet P by the leading end abutment surface 114b.

[0085] 8, the area of ​​contact with the sheet P is also larger for the retraction belt 116a and the assist belt 116b on the opposite side to the center of the stacking tray 106. This makes it easier to correct the skew of the sheet P by the leading end abutment surface 114b.

[0086] (Modification) In the above-described embodiment, an example has been described in which the timing (S4) of bringing the assist belt 116b into contact is the timing when the sheet P abuts against the abutment slope 114a of the leading edge stopper 114. However, the timing of bringing the assist belt 116b into contact may be any timing at which the assist belt 116b can apply a conveying force to the sheet P before the sheet P abuts against the leading edge abutment surface 114b. For example, the assist belt 116b may be brought into contact when the leading edge of the sheet P is detected by the sheet detection unit 312.

[0087] In the above embodiment, the assist belt 116b is described as being switched between two states, the contact state and the retracted state, but the assist belt 116b may be configured to be capable of taking an intermediate state. That is, the assist belt 116b may be configured to be capable of taking an intermediate state (light contact state) in which the assist belt 116b contacts the sheet on the stacking tray 106 with a contact pressure lighter than that of the contact state. Specifically, the driving roller pair 115b of the assist belt 116b is moved to a position between the upper position (FIG. 5(c)) and the lower position (FIG. 5(d)). In this case, the assist belt 116b may be in the intermediate state for a sheet that is lighter in weight than the sheet that brings the assist belt 116b into contact with the sheet and heavier than the sheet that brings the assist belt 116b into the retracted state.

[0088] In other words, the second retraction member may be provided to be switchable to an intermediate state in which the second retraction member contacts the sheets loaded on the stacking section with a weaker contact pressure than the contact state. Furthermore, the control means may be capable of executing a third mode in which the second retraction member is in the intermediate state and the sheets are retracted by the first retraction member and the second retraction member. By selectively using the first mode, the second mode, and the third mode, good alignment can be achieved for a wider variety of sheets.

[0089] The contact pressure of the assist belts 116b against the sheet P may be changed in three or more stages. Furthermore, by arranging a plurality of sets of assist belts 116b and changing the number of sets of the assist belts 116b in a contact state, the conveying force applied to the sheet P by the entire plurality of sets of assist belts 116b may be changed in three or more stages. Furthermore, in addition to switching the assist belts 116b between a contact state and a retracted state, the retraction belt 116a may be configured to be switchable between a contact state and a retracted state.

[0090] In the above embodiment, the sheet contact area of ​​the retracting belt 116a in the sheet conveying direction D1 and the sheet contact area of ​​the assist belt 116b in the sheet conveying direction D1 are substantially the same as each other. Alternatively, the sheet contact area of ​​the assist belt 116b may be offset downstream in the sheet conveying direction D1 with respect to the sheet contact area of ​​the retracting belt 116a. For example, the upstream end position of the sheet contact area of ​​the assist belt 116b may be offset downstream in the sheet conveying direction D1 by several mm from the upstream end position of the sheet contact area of ​​the retracting belt 116a. In this case, regardless of whether the assist belt 116b is in a contact state or a retracted state, the retracting belt 116a is the first to come into contact with the conveyed sheet P. This avoids inconveniences such as the sheet being easily turned due to the assist belt 116b coming into contact first, and makes the behavior of the sheet more stable.

[0091] In the above embodiment, the assist belt 116b is disposed on the inner side of the retraction belt 116a in the seat width direction D2. However, the present invention is not limited to this, and the assist belt 116b may be disposed on the outer side of the retraction belt 116a in the seat width direction D2.

[0092] In the above-described embodiment, the first retraction member and the second retraction member are both endless belts having male ends. The first retraction member and the second retraction member are not limited to belts, and may be roller members or paddle members having elastic protrusions (paddles) on a rotating shaft. The first retraction member and the second retraction member may be different types, for example, the first retraction member may be a belt and the second retraction member may be a roller member.

[0093] 6, the assist belt 116b is rotated even when the assist belt 116b is in the retracted state, but the rotation of the assist belt 116b may be stopped when the assist belt 116b is in the retracted state. In this case, for example, a clutch unit such as an electromagnetic clutch may be provided on the drive transmission path from the belt drive motor 310 to the drive roller pair 115b. Also, a motor that rotates the assist belt 116b may be added in addition to the belt drive motor 310 that drives the retraction belt 116a.

[0094] In the above-described embodiment, the grippers 107a and 107b grip the leading edge of the sheet, and the leading edge of the sheet comes into contact with the contact slope 114a, thereby releasing the sheet from the grippers 107a and 107b. However, the present invention is not limited to this, and the grippers 107a and 107b may be configured to be openable and closable, and the grippers 107a and 107b may be opened when the leading edge of the sheet approaches the leading edge contact surface 114b, thereby releasing the sheet.

[0095] Also, the grippers 107a, 107b and the gripper belt 108 may be omitted, and the pair of discharge rollers 105 may directly convey the sheet onto the stacking tray 6. Also, the direction in which the pair of discharge rollers 105 conveys the sheet may be different from the direction in which the retraction belt 116a conveys the sheet. For example, the pair of discharge rollers 105 may convey the sheet in a direction opposite to the direction in which the retraction belt 116a moves the sheet toward the leading end stopper 114, and discharge the sheet onto the stacking tray 106. In this case, the sheet discharged onto the stacking tray 106 may be moved in the sheet conveying direction toward the leading end stopper 114 by a conveying member (paddle, roller, etc.), and may be abutted against the leading end stopper 114 by the retraction belt 116a.

[0096] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0097] 105, 107a, 107b, 108...conveying means (pair of discharge rollers, gripper, gripper belt) / 106...loading section (loading tray) / 114b...butting section (tip butting surface) / 116a...first pulling member (pulling belt) / 116b...second pulling member (assist belt) / 210...control means (stacker control section)

Claims

1. The loading section where the sheets are loaded, A conveying means for conveying the sheet toward the loading section in the sheet conveying direction, The leading edge of the sheet in the sheet transport direction is abutted against a part, A first conveying member that contacts the sheet loaded on the loading section and applies a conveying force to the sheet so that the leading edge of the sheet faces the abutting section, A second conveying member that contacts the sheet loaded on the loading section and applies a conveying force to the sheet so that the leading edge of the sheet faces the abutting section, the second conveying member being movable between a contact position in contact with the sheet loaded on the loading section and a retracted position retracted from the sheet loaded on the loading section, A control means capable of executing a first mode in which the sheet is transported by the first and second transport members with the second transport member positioned at the contact position, and a second mode in which the sheet is transported by the first transport member with the second transport member positioned at the retracted position, A sheet loading device characterized by having the following features.

2. The control means determines whether to execute the first mode or the second mode based on sheet information relating to the sheet to be loaded in the loading section. The sheet loading device according to feature 1.

3. The control means executes the first mode when loading a sheet with a first basis weight, and executes the second mode when loading a sheet with a second basis weight smaller than the first basis weight. The sheet loading device according to feature 1.

4. The control means executes the first mode when loading a sheet of a first size, and executes the second mode when loading a sheet of a second size having a smaller area than the first size. The sheet loading device according to feature 1.

5. The control means executes the first mode when loading a sheet of the first material, and executes the second mode when loading a sheet of the second material having a lower density than the first material. The sheet loading device according to feature 1.

6. The second conveying member is arranged alongside the first conveying member in the sheet width direction perpendicular to the sheet conveying direction. The sheet loading device according to feature 1.

7. The second conveying member is positioned inward of the first conveying member in the sheet width direction. The sheet loading device according to feature 6.

8. The abutment portion includes a first surface extending in the sheet width direction, and a second surface adjacent to the first surface on the outside in the sheet width direction and inclined downstream in the sheet conveying direction toward the outside in the sheet width direction. The boundary between the first surface and the second surface is located outside the second conveying member and inside the first conveying member in the sheet width direction. The sheet loading device according to feature 7.

9. A third conveying member is positioned opposite the first conveying member to the center of the loading section in the sheet width direction and symmetrically to the first conveying member, and is in contact with the sheet loaded in the loading section, applying a conveying force to the sheet so that the leading edge of the sheet faces the abutting portion, A fourth conveying member is positioned opposite the second conveying member to the center of the loading section in the sheet width direction and symmetrically with respect to the second conveying member, and contacts the sheet loaded in the loading section to apply a conveying force to the sheet so that the leading edge of the sheet faces the abutting portion, the fourth conveying member is provided to be movable between a position in contact with the sheet loaded in the loading section and a position retracted from the sheet loaded in the loading section, Furthermore, The sheet loading device according to feature 7.

10. The first and second conveying members are positioned in the sheet width direction, inward from the side edge position of the sheet with the shortest length in the sheet width direction among the sheets that the sheet loading device can load onto the loading section. The sheet loading device according to feature 6.

11. The contact area of ​​the second conveying member with respect to the sheet loaded in the loading section is offset downstream in the sheet conveying direction with respect to the contact area of ​​the first conveying member with respect to the sheet loaded in the loading section. The sheet loading device according to feature 6.

12. The second transport member is elastic and formed in an endless shape. The aforementioned sheet loading device is A pair of rollers that grip the second conveying member, The drive unit includes a drive unit that drives the roller pair to move up and down relative to the loading section so that the second transport member moves between the contact position and the retracted position, The sheet loading device according to feature 1.

13. The second transport member is movable to an intermediate position where it contacts the sheet loaded on the loading section with a weaker contact pressure compared to the contact position. The control means is capable of executing a third mode in which the sheet is transported by the first and second transport members by positioning the second transport member at the intermediate position. The sheet loading device according to feature 1.

14. The conveying means is A rotating belt is provided above the aforementioned loading section, A gripper is provided on the aforementioned belt to hold the sheet, including, The sheet loading device according to feature 1.

15. The first transport member elastically deforms upon contact with the upper surface of the sheet loaded on the loading section. The second conveying member at the contact position contacts the upper surface of the sheet loaded on the loading section and undergoes elastic deformation. The sheet loading device according to feature 1.

16. An image forming apparatus body equipped with an image forming means for forming an image on a sheet, A sheet loading device according to any one of claims 1 to 15, The sheet loading device is equipped with a sheet on which an image has been formed and loads the sheet from the main body of the image forming apparatus. An image forming apparatus characterized by the following features.

Images