JP4748820B2 - Sheet stacking apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet stacking apparatus that stacks sheets by improving the consistency in the sheet discharge direction, and in particular, a sheet stacking apparatus that can stack a large capacity sheet by making the best use of space, and this sheet stacking apparatus. The present invention relates to an image forming apparatus provided.

  2. Description of the Related Art In recent years, image forming apparatuses that form images on sheets have been able to increase the image forming speed by improving the image forming technology, and can discharge a large number of sheets from the main body of the image forming apparatus at high speed. It became so. For this reason, even in a sheet stacking apparatus that is connected to the apparatus main body of the image forming apparatus and stacks sheets discharged from the apparatus main body, it is possible to stack sheets with a large capacity while maintaining sheet stacking consistency. It is demanded. A sheet stacking apparatus (hereinafter referred to as a “stacker apparatus”) that responds to this is described in Japanese Patent Application Laid-Open No. 2004-228688.

  This conventional stacker apparatus is shown in FIG. The stacker apparatus 500 receives a sheet discharged from the apparatus main body of the image forming apparatus by the entrance roller 501 and then delivers the sheet to the gripper 503 by the conveyance roller pair 502. The gripper 503 grips and conveys the sheet, and abuts the front end of the sheet against the front end stopper 504. When the sheet hits the leading end stopper 504, the sheet is detached from the gripper 503 and falls onto the stacker tray 505. At this time, the sheet falls between the front end stopper 504 and the rear end stopper 508, and the front end and the rear end are aligned. Further, if necessary, width alignment is performed by a width alignment mechanism (not shown), and sheet end portions (side end portions) in a direction perpendicular to the sheet conveying direction are aligned. Further, the sheet is pressed against the stacker tray 505 by the leading edge pressing member 506 and the trailing edge pressing member 507 every predetermined number of sheets so as not to interfere with the next sheet being discharged.

JP 2006-124052 A

  However, the conventional stacker device 500 has a stacking space for the maximum size sheet on the stacker tray 505, and when a small size sheet is stacked as shown in FIG. Sheets cannot be stacked. For this reason, the conventional stacker apparatus 500 has a dead space.

  Further, in the conventional stacker device 500, the distance between both stoppers is set to be several mm longer than the length in the sheet conveyance (discharge) direction so that the sheet can easily fall between the leading edge stopper 504 and the trailing edge stopper 508. is there. For this reason, in the conventional stacker apparatus 500, the sheets are stacked with a variation of several millimeters between the stoppers, and thus the sheet alignment is poor.

  Therefore, if the interval is adjusted to the length of the sheet in order to improve the consistency, the sheet falls over time while contacting both stoppers.

  For this reason, the conventional stacker apparatus 500 presses the sheet against the stacker tray 505 by the hitting member in order to shorten the sheet dropping time.

  However, the conventional stacker 500 has a problem in that at least one of the leading edge and the trailing edge of the sheet is rubbed against the stopper, and the sheet is stacked on the stacker tray 505 while damaging the sheet.

  In addition, the image forming apparatus provided with such a stacker device may have to perform image formation again on an image-formed sheet damaged by the stacker device, resulting in poor productivity.

  An object of the present invention is to provide a sheet stacking apparatus capable of stacking a large capacity sheet by maximizing space.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet stacking apparatus in which sheet alignment is improved by reducing damage to sheets discharged and stacked.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having a sheet stacking apparatus capable of stacking a large capacity sheet and having an improved image forming efficiency.

The sheet stacking apparatus of the present invention discharges a sheet to the stacking means from a plurality of stacking means for stacking sheets and a plurality of discharge positions provided above the corresponding stacking means corresponding to the plurality of stacking means. A discharge means, a stopper for restricting a sheet discharged from a selected discharge position among the plurality of discharge positions to a predetermined position on the stacking means corresponding to the selected discharge position , and the selected discharge And a common guide unit having a guide member that guides the downstream end of the sheet discharged in the discharge direction to the stopper along the downwardly inclined surface, and the common guide unit is a selected discharge unit. It is possible to move from a position to a position for regulating the sheet discharged onto the corresponding stacking means among the plurality of stacking means.

  Since the sheet stacking apparatus of the present invention has a plurality of stacking means arranged in the discharge direction, it is possible to stack large capacity sheets without enlarging the apparatus.

  In the sheet stacking apparatus of the present invention, the sheet discharged to the stacking unit is configured to be a stopper and the leading end of the sheet is aligned at a predetermined position, so that the sheet alignment can be improved.

  In the sheet stacking apparatus of the present invention, the leading edge and the trailing edge of the sheet are not aligned when they are rubbed, and the sheet is less likely to be damaged.

  Since the sheet stacking apparatus of the present invention sequentially discharges sheets from the discharge unit and receives them at predetermined positions, it is possible to stack a large number of sheets on the stacking unit at high speed.

FIG. 3 is a cross-sectional view of the image forming apparatus according to the embodiment of the present invention along the sheet conveying direction. FIG. 3 is a control block diagram for controlling the entire image forming apparatus having a sheet stacking apparatus. 5 is a flowchart for explaining basic operations of the stacker device. FIG. 3 is a cross-sectional view of the sheet stacking apparatus according to the first exemplary embodiment of the present invention along the sheet conveyance direction. FIG. 6 is a diagram for explaining an operation when sheets are stacked on the left stacker tray, and is a diagram in which sheets are held by a gripper. FIG. 6 is a diagram for explaining the operation continued from FIG. 5, in which a sheet is conveyed and discharged to the sheet guide unit. FIG. 7 is a diagram for explaining the operation continued from FIG. 6 and is a diagram immediately before a sheet is guided by the taper portion of the sheet guiding unit and stacked on the preceding sheet. FIG. 8 is a diagram for explaining operation following FIG. 7, in which sheets are stacked on a preceding sheet. FIG. 9 is a diagram for explaining the operation continued from FIG. 8, in which sheets are stacked up to a predetermined stacking height on one stacker tray. FIG. 6 is a diagram for explaining an operation when sheets are stacked on the right stacker tray, and is a diagram in which sheets are held by a gripper. It is a figure for operation | movement description which continues from FIG. 10, and is a figure by which the sheet | seat is conveyed and discharged by the sheet guide unit. FIG. 12 is a diagram for explaining the operation continued from FIG. 11, in which the sheets are guided on the taper portion of the sheet guide unit and stacked on the stacker tray. FIG. 13 is a diagram for explaining the operation continued from FIG. 12, in which sheets are stacked on both stacker trays to a predetermined stacking height. It is a perspective view which conveys a sheet | seat with a dolly. It is a figure of the sheet stacking apparatus which has a part which discharges | emits a sheet for every stacker tray as a sheet stacking apparatus in the 2nd Embodiment of this invention. FIG. 10 is a cross-sectional view of a conventional sheet stacking apparatus along a sheet conveying direction.

Hereinafter, a sheet stacking apparatus according to a first embodiment of the present invention and an image forming apparatus including the sheet stacking apparatus according to the first embodiment in an apparatus body will be described with reference to the drawings. Note that the sheet stacking apparatus according to the second embodiment of the present invention is also provided in the image forming apparatus instead of the sheet stacking apparatus according to the first embodiment .

(Image forming device)
FIG. 1 is a cross-sectional view taken along the sheet conveying direction of the image forming apparatus according to the first embodiment of the present invention. The image forming apparatus 900 includes a sheet stacking apparatus (hereinafter referred to as “stacker apparatus”) 100 in the apparatus main body 900A. The stacker apparatus 100 is connected as an option to the apparatus main body 900A, but may be incorporated in the apparatus main body 900A.

  The apparatus main body 900A includes an image reader 951 and an automatic document feeder 950 in the upper part. The sheet S set in the sheet feeding cassettes 902a to 902e is conveyed to the registration roller pair 910 by the sheet feeding rollers 903a to 903e and the conveying roller pair 904.

  On the other hand, a photosensitive drum 906 that constitutes an image forming unit together with a transfer device 905 and a developing device 909 described later is exposed by an exposure unit 908 while being charged by a primary charger 907. On the photosensitive drum 906, digital document data of the document read by the image reader 951 is formed as an electrostatic latent image. Thereafter, the developing device 909 develops the photosensitive drum 906 with toner, and turns the electrostatic latent image into a toner image.

  Then, the sheet is fed between the photosensitive drum 906 and the transfer device 905 by the registration roller pair 910 in accordance with the position of the toner image. The transfer unit 905 transfers the toner image from the photosensitive drum 906 to a sheet. Foreign matter such as residual toner adhering to the photosensitive drum 906 without being transferred to the sheet is scraped off by the blade of the cleaning device 913. As a result, the surface of the photosensitive drum 906 is cleaned to prepare for the next image formation.

  The sheet onto which the toner image has been transferred is conveyed to the fixing device 912 by the conveying belt 911, and is sandwiched between the heating roller and the pressure roller of the fixing device 912 and heated and pressed to fix the toner image. The sheet on which the toner image is fixed is conveyed as it is to the stacker apparatus 100 by the discharge roller pair 914 or is conveyed to the double-side reversing apparatus 901 by the switching member 915 and again on the opposite surface. A toner image is formed.

(Control block diagram)
FIG. 2 is a control block diagram for controlling the entire image forming apparatus. The CPU circuit unit 206 includes a CPU (not shown), a ROM 207, and a RAM 208, and comprehensively controls each of the blocks 202, 209, 203, 204, 201, 205, and 210 by a control program stored in the ROM 207. It is like that. The RAM 208 temporarily stores control data and is used as a work area for arithmetic processing associated with control.

  A DF (document feeding) control unit 202 controls driving of the automatic document feeder 950 based on an instruction from the CPU circuit unit 206. The image reader control unit 203 performs drive control on the above-described scanner unit, image sensor, and the like of the image reader, and transfers an analog image signal output from the image sensor to the image signal control unit 204.

  The image signal control unit 204 converts each analog image signal from the image sensor into a digital signal, performs each process, converts the digital signal into a video signal, and outputs the video signal to the apparatus main body control unit, that is, the printer control unit 205. It has become. The image signal control unit 204 performs various processes on the digital image signal input from the computer 200 via the external I / F 201, converts the digital image signal into a video signal, and outputs the video signal to the printer control unit 205. . The processing operation by the image signal control unit 204 is controlled by the CPU circuit unit 206.

  The printer control unit 205 drives the above-described exposure unit 908 based on the input video signal.

  The operation unit 209 includes a plurality of keys for setting various functions relating to image formation, a display unit for displaying information indicating a setting state, and the like. The operation unit 209 outputs a key signal corresponding to the operation of each key to the CPU circuit unit 206 and displays corresponding information on the display unit of the operation unit 209 based on the signal from the CPU circuit unit 206. .

  The stacker control unit 210 is mounted on the stacker device 100 and performs drive control of the entire stacker device by exchanging information with the CPU circuit unit 206. This control content will be described later.

(Basic operation of the stacker unit)
The basic operation of the stacker apparatus will be described based on the flowchart of FIG. 3 and the cross-sectional view of the stacker apparatus of FIG.

  A sheet discharged from the apparatus main body 900 </ b> A of the image forming apparatus 900 (FIG. 1) is conveyed into the stacker apparatus 100 by the inlet roller pair 101 of the stacker apparatus 100, and is conveyed to the switching member 103 by the conveyance roller pair 102. Before the sheet is conveyed, sheet information is sent in advance from the CPU circuit unit 206 of the image forming apparatus 900 to the stacker control unit 210 (FIG. 2) (S301). The sheet information includes sheet size, paper type, sheet discharge destination information, and the like.

  When the discharge destination of the sheet is the top tray 106 (S302), the switching member 103 is switched to the position of the leading edge downward indicated by the broken line by a solenoid (not shown) (S303), and the sheet is guided to the conveying roller pair 104. The sheet thus conveyed is discharged onto the top tray 106 by the discharge roller pair 105 and stacked (S304).

  When the sheet discharge destination is the stacker tray 112a or 112b (S305), the sheet conveyed by the conveying roller pair 102 is guided by the switching member 103 that is switched upward at the leading end indicated by a solid line by a solenoid (not shown), and is conveyed to the conveying roller. It is conveyed to the pair 107. Then, the sheet is guided to the discharge roller pair 110 constituting the discharge means by the outlet switching member 108 that is switched leftward at the upper end indicated by the solid line. The sheet is delivered to grippers 114a and 114b constituting the discharge unit by the discharge roller pair 110 capable of discharging the sheet, and is selectively discharged and stacked on the stacker trays 112a and 112b as stacking units (on the stacking unit). (S306). This discharge operation will be described later. That is, the sheets are stacked according to the selected stacker trays 112a and 112b.

  When the sheet discharge destination is conveyed further to a downstream stacker (not shown) (S307), the exit switching member 108 is switched to the upper right position indicated by a broken line (S308). The sheet transported by the transport roller pair 102 is transported by the transport roller pair 107, guided to the exit roller pair 109, and then transported to the downstream stacker device.

(Explanation of operation to discharge the sheet to the stacker tray)
The operation of discharging a sheet to the stacker tray will be described with reference to FIGS. The stacker trays 112a and 112b are supported by support members 131a and 131b that are moved up and down by a drive device (not shown), and are arranged so as to be able to move up and down individually in the directions of arrows C, D, E, and F in FIG.

  The guide unit 115 is attached to the slide shaft 118 so that the frame 127 can be moved, and is moved in the directions of arrows A and B by a drive device (not shown). The frame 127 of the guide unit 115 is formed with a stopper 121 that regulates and positions the sheet at a predetermined position, and a tapered portion 122 that guides the sheet to the stopper 121, and a knurled belt 116 that has elasticity to pull the sheet into the stopper 121. I have.

  The tapered portion 122 serving as a guide member, the knurled belt 116 serving as a rotating body, and the stopper 121 constitute a guide unit serving as a common guide means for the stacker trays 112a and 112b. The sheet guided by the taper portion 122 and the knurled belt 116 is aligned at a predetermined alignment position (regulation position) with the leading end in the sheet discharge direction by the discharge roller pair 110 abutting against the stopper 121.

  The knurled belt 116 rotates counterclockwise by a driving device (not shown), draws the sheet between the knurled belt 116 and the stacker tray 112a (or the stacker tray 112b), and abuts the leading end of the sheet against the stopper 121. It is like that. The paper surface detection sensor 117 is a sensor that is incorporated in the guide unit 115 and is provided to keep the distance from the guide unit 115 to the upper surface of the sheet constant.

  The grippers 114a and 114b that grip the leading end portion of the sheet and convey the sheet are attached to the drive belt 130 in a state where the gripper 114a and 114b is biased in a direction to close the opening by a torsion coil spring (not shown). The sheet is held by the sheet discharged by the discharge roller pair 110 being pushed into the grippers 114a and 114b. The gripper may be provided with an elastic body such as a sponge above and below the opening of the V-shaped member, and hold the sheet pushed between the upper and lower elastic bodies.

  Stacker trays 112a and 112b serving as stacking units are trays on which discharged sheets are stacked, and stand by at home position positions for stacking sheets by home position detection sensors 113a and 113b.

  As shown in FIG. 5, the sheet S discharged from the apparatus main body 900 </ b> A (FIG. 1) of the image forming apparatus 900 is conveyed to the discharge roller pair 110. Then, the timing at which the sheet passes is detected by a timing sensor 111 disposed upstream of the discharge roller pair 110. At this timing, the drive belt 130 starts to circulate so that the gripper 114a that is stopped and waiting is conveyed while gripping the leading edge of the sheet S. Thereafter, the gripper 114a moves closer to the guide unit 115 while holding the sheet (FIG. 6). The drive belt 130 and the grippers 114a and 114b constitute discharge means.

  Then, as shown in FIG. 7, when the gripper 114a passes through the tapered portion 122 of the guide unit 115, the sheet S is guided by the tapered portion 122 with the momentum that has been conveyed away from the gripper 114a, and the stacker tray It is biased to the 112a side. The sheet then enters between the knurled belt 116 and the stacker tray 112a (or the uppermost sheet when sheets are stacked). Thereafter, as shown in FIG. 8, the sheet S is conveyed by the knurled belt 116 until the leading end abuts against the stopper 121. As a result, the sheet is stacked (aligned) at a predetermined position on the stacker tray 112a and stacked on the stacker tray 112a or the uppermost sheet.

  Thereafter, the alignment plate 119 performs a jogging operation in a direction perpendicular to the sheet conveying direction (sheet width direction) to align the side edges of the sheets (width alignment).

  The paper surface detection sensor 117 constantly monitors the upper surface of the sheets stacked on the stacker tray 112a. When the interval between the knurled belt 116 and the sheet of the guide unit 115 becomes narrower than a predetermined amount, the stacker tray 112a is lowered by a predetermined amount by a driving device (not shown). As a result, the distance between the knurled belt 116 and the sheet is maintained at a predetermined distance.

  In the stacker apparatus 100, the driving belt 130 circulates, and the two grippers 114a and 114b alternately discharge and convey the sheets, and sequentially stack the sheets on the stacker tray 112a.

  When it is detected that the sheets stacked on the stacker tray 112a have reached a predetermined stacking height, it is determined that the sheets are full. The fact that the stacked sheets have reached a predetermined stacked height is normally detected by detecting the sheet S discharged from the discharge roller pair 110 by the timing sensor 111 and counting it by the stacker control unit 210 (FIG. 2). . Alternatively, the position of the stacker tray 112a and the position of the uppermost sheet are detected and detected.

  When the sheets on the stacker tray 112a reach a predetermined stacking height, as shown in FIG. 9, the stacker control unit 210 (FIG. 2) controls the stacker tray 112a to move down to transport the stacked sheets together with the stacker tray. To be placed on a dolly 120 as a cart. Thereafter, the guide unit 115 moves in the direction of arrow A. Then, the stacker tray 112b waits for sheets to be stacked.

  It is preferable that the standby position of the guide unit 115 is approximately the center of the sheets stacked on the stacker trays 112a and 112b, so that the stacked state of the sheets is stable, but the stacked sheets protrude from the stacker trays 112a and 112b. If there is no range, there is no problem.

  As shown in FIG. 10, after the sheet discharged from the apparatus main body of the image forming apparatus passes through the timing sensor 111, the sheet is discharged from the discharge roller pair 110, and the leading end of the sheet is gripped by the gripper 114a. As shown in FIGS. 11 and 12, when the gripper 114 a passes through the tapered portion 122 of the guide unit 115, the leading end portion of the sheet S is urged toward the stacker tray 112 b by the tapered portion 122. The sheet moves along the tapered portion 122 and is guided to the knurled belt 116.

  Thereafter, the leading end of the sheet S is abutted against the stopper 121 by the knurled belt 116. The sheets S are stacked on the stacker tray 112 b with the leading ends aligned, and further, the side edges are aligned by the alignment plate 119.

  The paper surface detection sensor 117 constantly monitors the upper surface of the sheets stacked on the stacker tray 112b. When the interval between the knurled belt 116 and the sheet of the guide unit 115 becomes narrower than a predetermined amount, the stacker tray 112b is lowered by a predetermined amount by a driving device (not shown). As a result, the distance between the knurled belt 116 and the sheet is maintained at a predetermined distance.

  In the stacker apparatus 100, the driving belt 130 circulates, and the two grippers 114a and 114b alternately discharge and convey the sheets, and sequentially stack the sheets on the stacker tray 112b.

  When it is detected that the sheets stacked on the stacker tray 112b have reached a predetermined stacking height, it is determined that the sheets are full. The fact that the stacked sheets have reached a predetermined stacked height is normally detected by detecting the sheet S discharged from the discharge roller pair 110 by the timing sensor 111 and counting it by the stacker control unit 210 (FIG. 2). . Alternatively, the position of the stacker tray 112b and the position of the uppermost sheet (the uppermost surface of the sheet) are detected and detected.

  When the sheets on the stacker tray 112b reach a predetermined stacking height, the stacker control unit 210 (FIG. 2) controls the stacker tray 112b to descend and places it on the dolly 120 as shown in FIG.

  The guide unit 115 moves in the direction of arrow B and stands by on the left stacker tray 112a as the uppermost stacking means.

  The stacker trays 112a and 112b are supported by a pair of support members 131a and 131b which are moved up and down by a driving device (not shown). The stacker trays 112a and 112b are transferred to the dolly 120 when the support members 131a and 131b are lowered from the support surfaces 120a and 120b of the dolly 120. As shown in FIG. 14, the stacker trays 112 a and 112 b on which large-capacity sheet bundles are stacked are engaged with a fixing member (not shown) such as a pin provided on the upper surface of the dolly 120 and slipped off the dolly 120. It is placed on the dolly 120 in such a way that there is no such thing. The dolly 120 is provided with a caster 125 and a handle 126. By moving the dolly 120 with the handle 126, a large-capacity sheet bundle can be easily moved at once.

  After the dolly 120 is unloaded from the stacker apparatus 100, the sheet bundle loaded on the stacker trays 112a and 112b on the dolly 120 is removed by the user. The stacker apparatus 100 is stopped until the dolly enters the lower part of the stacker apparatus 100 again. Alternatively, the spare dolly 120 and the stacker trays 112a and 112b are prepared, the spare dolly 120 is advanced into the stacker device 100, and the spare stacker trays 112a and 112b are supported by the pair of support members 131 to be stacked. 100 may be activated.

The stacker device according to the first embodiment described above is configured to convey a sheet to a plurality of stacker trays with grippers. However, the stacker apparatus 300 as the sheet stacking apparatus in the second embodiment of the present invention shown in FIG. 15 is provided with discharge roller pairs 110 and 124 as discharge means on each stacker tray (for each stacking means). Thus, the sheet is discharged from the roller pair to each stacker tray. The stacker device 300 is different from the stacker device 100 described above in that the pair of discharge rollers 110 and 124 are provided instead of the grippers 114a and 114b and the drive belt 130, and the other parts are the same in configuration. The illustration and description of other parts are omitted.

  That is, when the sheets are stacked on the stacker tray 112a, the guide unit 115 is placed on the stacker tray 112a and the sheet is discharged from the discharge roller pair 110 toward the guide unit 115. When stacking sheets on the stacker tray 112b, the guide unit 115 is placed on the stacker tray 112b and the sheet is discharged from the discharge roller pair 124 toward the guide unit 115. Selection of the discharge roller pair 110 and the discharge roller pair 124 is performed by switching the switching member 123.

In addition, the stacker apparatus according to the first and second embodiments of the present invention has two stacker trays, but may have three or more.

In the second embodiment , the front end of the sheet is gripped by the gripper and conveyed. However, an air suction device as an air suction unit that sucks air and sucks the front end of the sheet is provided. It may be provided on the driving belt 130 so as to suck and convey the sheet. Furthermore, an electrostatic suction device as an electrostatic suction unit that sucks the leading edge of the sheet with static electricity may be provided on the driving belt 130 to transport the sheet.

  Accordingly, since the stacker apparatuses 100 and 300 described above are configured to stack sheets on the plurality of stacker trays 112a and 112b, the space in the apparatus can be used effectively.

  Further, since the stacker apparatuses 100 and 300 are configured to receive the leading edge of the sheet dropped on the stacker trays 112a and 112b with the stopper 121, the sheet alignment can be improved.

  Furthermore, since the stacker apparatuses 100 and 300 sequentially discharge the sheets from the discharge unit and receive them with the stoppers, it is possible to stack a large number of sheets on the stack unit at a high speed.

  Further, since the stacker devices 100 and 300 are aligned by bringing the leading end of the sheet into contact with the stopper 121, damage to the leading end of the sheet is reduced.

  Further, since the image forming apparatus 900 includes a sheet stacking apparatus that can stack a large volume of sheets, the number of stops can be reduced and the image forming efficiency can be increased.

  Further, since the image forming apparatus 900 includes the stacker apparatuses 100 and 300 that do not damage the front end of the sheet, it is less necessary to re-form the image on the sheet, and the image forming efficiency can be improved. .

S sheet 100 sheet stacking device (stacker device)
110 Discharge roller pair (discharge means)
112a Stacker tray (loading means, uppermost stacking means)
112b Stacker tray (loading means)
113a, 113b Home position detection sensors 114a, 114b Gripper (discharge means)
115 Guide unit (guide means)
116 knurled belt (rotary body, transfer means)
120 dolly 121 stopper 122 taper part (guide member, transfer means)
124 discharge roller pair (discharge means)
130 Drive belt (discharge means)
205 Printer Control Unit 206 CPU Circuit Unit 210 Stacker Control Unit 300 Sheet Stacking Device (Stacker Device)
900 Image forming apparatus 900A Main body 906 Photosensitive drum (image forming means)
950 Automatic document feeder

Claims (4)

A plurality of stacking means for stacking sheets;
Discharging means for discharging sheets to the stacking means from a plurality of discharge positions provided above the corresponding stacking means corresponding to the plurality of stacking means ;
A stopper that regulates a sheet discharged from a selected discharge position among the plurality of discharge positions to a predetermined position on the stacking unit corresponding to the selected discharge position, and discharged from the selected discharge position. A common guide means having a guide member for guiding the downstream end of the discharged sheet in the discharge direction to the stopper along a downwardly inclined surface ;
The common guide means is movable from a selected discharge position to a position that regulates a sheet discharged onto a corresponding stacking means among the plurality of stacking means.
A sheet stacking apparatus characterized by that. The stacking means can be moved up and down so that the uppermost surface of the stacked sheets is positioned at a predetermined height position.
The sheet stacking apparatus according to claim 1, wherein: It said common guide means comprises a rotary member for moving the sheet guided by the guide member toward the stopper,
The sheet stacking apparatus according to claim 1 , wherein: Image forming means for forming an image on a sheet;
The sheet stacking apparatus according to any one of claims 1 to 3 , wherein sheets on which images are formed are stacked.
An image forming apparatus.

Images