JP4862384B2 - Post-processing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a post-processing device capable of stacking a larger number of Z-folded sheets on a sheet stacking tray while effectively preventing a stacking failure of Z-folded sheets and sheets other than the Z-folded sheets. <P>SOLUTION: This post-processing device is provided with the sheet stacking tray provided in a device body with the main face of the tray inclined, and having a movable tray at a tray end in the device body side; a posture change motor 41 driven to change a posture of the movable tray between an inclined posture along the main face of the tray and a horizontal posture along the horizontal face of the tray; a discharge motor 39 driven to discharge sheets on the sheet stacking tray; a sheet folding mechanism 20 for applying folding processing to sheets; and a control part 38 counting the number of discharged Z-folded sheets and driving the posture change motor 41 to change the posture of the movable tray from the inclined posture to the horizontal posture when the counted value reaches a predetermined value. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a post-processing apparatus that performs a folding process on a sheet and an image forming apparatus including the post-processing apparatus.

  Some image forming apparatuses such as copiers, printers, and multifunction peripherals and post-processing apparatuses attached thereto include a sheet folding unit that performs a predetermined folding process on a sheet fed from the main body of the image forming apparatus. Sheet folding processing is mainly divided into two-fold, three-fold, and Z-fold. Bi-folding is to fold a sheet in half at the original half size. Tri-folding is to fold a sheet in three with the original size of 1/3. The tri-fold includes an inner tri-fold where the sheet is folded inward and an outer tri-fold where the sheet is folded outward. Since this tri-fold is often used when a sheet is stored in an envelope, it is also called an envelope fold.

  On the other hand, Z-folding is a method of folding a sheet into three at half the original size. Specifically, as shown in FIG. 13, the entire sheet is formed by making creases from the downstream sheet edge in the sheet conveying direction to ¼ and ½ of the original sheet length L, respectively. It folds into a letter shape. For this reason, for example, when a sheet of A3 landscape size is Z-folded, it becomes the same size as a sheet of A4 portrait size. Further, when a B4 landscape sheet is Z-folded, it becomes the same size as a B5 portrait sheet. For this reason, Z-folding is used when you want to eject an A3 landscape sheet in the same size as an A4 portrait sheet, or when you want to eject a B4 landscape sheet in the same size as a B5 portrait sheet. Is done. The Z-folded sheet (hereinafter also referred to as “Z-folded sheet”) is finally discharged to the sheet stacking tray. At that time, when a large number of Z-folded sheets are discharged in one job, a large number of Z-folded sheets are stacked on the sheet stacking tray.

  As shown in FIG. 13, the Z-fold sheet has a Z-shaped fold. For this reason, as shown in FIG. 14, when a large number of Z-folded sheets Sz are stacked on the sheet stacking tray Tr for discharging the sheet, the stacking form of the entire sheets is in a mountain shape due to the bulging of the folded portion of each Z-folded sheet Sz. It becomes the form which swollen. Therefore, if the stacking of the sheets is continued in the mountain shape, the sheet discharge port is blocked by the Z-folded sheet Sz when reaching a certain stacking height, or the folding of the folded portion and the buckling due to its own weight causes the Z The folded sheet Sz falls down, and thereafter, the sheet cannot be discharged to the sheet stacking tray Tr.

  Therefore, as a related art related to sheet folding processing including Z-folding, for example, Patent Document 1 listed below discloses a part of a bin tray that forms an upward inclined surface in order to stack a large number of Z-folded sheets in a stable state. A technique has been proposed in which an auxiliary sheet placing plate is provided on the upper side and the auxiliary sheet placing plate is raised by the lowering of the bin tray and inclined in the direction opposite to the inclined surface.

  Although not related to sheet folding processing, as a related art related to sheet stapling processing, for example, in Patent Document 2 below, a movable plate is provided on a stacking tray that moves up and down according to the amount of discharged sheets. There has been proposed a technique for moving the movable plate from a position inclined with respect to the sheet discharge direction to a position substantially parallel to the sheet discharge direction.

Japanese Patent Laid-Open No. 61-217462 Japanese Patent Laid-Open No. 10-250896

  In general, the sheet stacking tray that can be moved up and down is lowered so as to be separated from the sheet discharge port each time the sheet stacking height reaches a predetermined height. This is because when the sheet stacking tray is lowered, the level difference between the sheet discharge port and the sheet stacking tray becomes larger, and more sheets can be stacked on the sheet stacking tray using this level difference. is there.

  However, in the prior art described in Patent Document 1, one end of the auxiliary sheet placing plate is engaged with the apparatus main body, and the auxiliary sheet placing plate is rotatably supported by using the engaging portion as a fulcrum. Since the auxiliary sheet stacking plate is tilted in conjunction with the raising and lowering operation of the bin tray, even if the bin tray is lowered according to the sheet stacking height, the auxiliary sheet stacking plate The engaging portion is always held at the same height position. For this reason, even if the bin tray is lowered, it is not possible to significantly increase the sheet stacking amount. In addition, the auxiliary sheet stacking plate is inclined by the lowering of the bin tray regardless of whether the sheet is Z-folded, so that the auxiliary sheet stacking plate is raised and inclined in the direction opposite to the inclined surface. When a sheet that is not Z-folded is discharged, there is a possibility that the sheet is uneven on the bin tray or pulled into the discharge roller.

  On the other hand, in the prior art described in Patent Document 2, when a bundle of stapled sheets is discharged, the movable plate is moved to a position substantially parallel to the sheet discharge direction. The job including processing cannot be appropriately handled. The sheet discharge direction is substantially parallel to the horizontal plane (surface perpendicular to the direction of gravity), but the sheet discharge direction is set to the horizontal plane for some reason (for example, to reduce contact resistance during sheet discharge). However, when it is desired to incline in the same direction as the stacking tray, it is necessary to tilt the stacking tray at a larger angle than the sheet discharge direction. In such a case, the sheet stacking space formed between the apparatus main body and the stacking tray is narrowed, and the inclination angle of the sheet stacking surface is increased, which is disadvantageous for stacking Z-folded sheets.

The present invention has been made to solve the above problems, and has as its object, while effectively preventing the loading failure of the sheet other than the folded Z folded sheets or Z, more Z folded sheets Sheet An object of the present invention is to realize a post-processing device that can be loaded on a loading tray.

The post-processing apparatus according to the present invention includes a tray main body provided in the apparatus main body with the main surface inclined, a movable tray provided at a tray end on the apparatus main body, the tray main body, and the movable A sheet stacking tray having a rotation support unit that connects the tray unit and rotatably supports the movable tray unit, and the inclination of the movable tray unit along the main surface of the tray main body unit and the horizontal plane Posture changing means for driving to change between horizontal postures along the sheet, sheet discharge means for discharging sheets to the sheet stacking tray, and a sheet for performing Z-folding as a folding process on the sheets before being discharged to the sheet stacking tray The number of sheets discharged by the folding unit and the sheet folded by the sheet folding unit is discharged to the sheet stacking tray by the sheet discharging unit, and the counted value is set to a predetermined value. When it reaches, a control means for changing the position of the movable tray portion by driving the posture changing means to the horizontal attitude from the inclined attitude, the sheet stacking tray by said sheet discharging means Control means for controlling the position of the movable tray unit to change from the tilted position to the horizontal position in accordance with the ratio of the Z-folded sheet to all discharged sheets .

  In the post-processing apparatus according to the present invention, when executing a job including a sheet folding process, the timing for changing the position of the movable tray unit from the inclined position to the horizontal position is based on the number of discharged sheets after the folding process. Can be controlled appropriately.

  According to the post-processing apparatus of the present invention, when executing a job including a sheet folding process, the posture of the movable tray unit is changed from an inclined posture to a horizontal posture at an appropriate timing, so that More Z-folded sheets can be stacked on the sheet stacking tray while effectively preventing other sheet stacking defects.

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

  FIG. 1 is a schematic diagram showing a configuration example of an image forming apparatus to which the present invention is applied. The illustrated image forming apparatus 1 is mainly composed of an image forming apparatus main body 2 and a post-processing apparatus main body 3. The image forming apparatus main body 2 includes an image forming unit 4 and a connecting unit 5, and the post-processing apparatus main body 3 includes a pre-stage post-processing unit 6 and a post-stage post-processing unit 7.

  The image forming unit 4 forms an image on a sheet supplied from a sheet supply tray based on, for example, an electrophotographic system. More specifically, the image forming unit 4 includes, for example, an image reading device (such as an image scanner) that optically reads an image of a document, and prints image data of the document read by the image reading device on a sheet as a visible image. Output. The image forming unit 4 includes, for example, a quadruple tandem type including four photosensitive drums 8, 9, 10, and 11 corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K). The machine configuration is as follows.

  In the above machine configuration, for example, when a full-color image is formed on a sheet, toner images of each color of YMCK are formed on the surfaces of the four photosensitive drums 8 to 11 by charging, exposing and developing, respectively, and A full-color toner image is formed on the intermediate transfer body 12 by sequentially superimposing and transferring (primary transfer) each color toner image from the body drums 8 to 11 to the endless belt-shaped intermediate transfer body 12. Thereafter, the toner image is collectively transferred (secondary transfer) onto the sheet by the transfer device 13 provided on the traveling path of the intermediate transfer body 12, and then the toner is fixed on the surface of the sheet by the fixing device 14. When a black and white image is formed on a sheet, a K-color toner image is formed on the surface of the photosensitive drum 11 by charging, exposing and developing, and the toner image is transferred from the photosensitive drum 11 to the intermediate transfer member 12. After the transfer, the image is transferred to a sheet by the transfer device 13 and fixed by the fixing device 14. The sheet on which the image is formed in this manner is sent from the image forming unit 4 to the connecting unit 5.

  The connecting unit 5 connects the image forming apparatus main body 2 and the post-processing apparatus main body 3 and delivers the sheet sent from the image forming unit 4 to the pre-stage post-processing unit 6. The connecting unit 5 has a sheet conveyance path for sheet delivery. The sheet conveyance path of the connecting unit 5 is formed so as to connect the exit part (sheet discharge port) of the sheet conveyance path of the image forming unit 4 and the inlet part (sheet intake port) of the sheet conveyance path of the pre-stage post-processing unit 6. ing. Further, a curl correction mechanism 15 is provided in the middle of the sheet conveyance path of the connection unit 5. The curl correction mechanism 15 corrects (removes) the curl of the sheet conveyed in the connection unit 5.

  The pre-stage post-processing unit 6 includes a sheet folding mechanism 20 including a first sheet folding unit 16 and a second sheet folding unit 17 in addition to the sheet conveyance path. The sheet folding mechanism 20 performs a folding process on the sheet. More specifically, the sheet folding mechanism 20 performs Z folding as a sheet folding process. The first sheet folding unit 16 folds the sheet conveyed in the pre-stage post-processing unit 6 at the first fold position. The second sheet folding unit 17 folds the sheet conveyed in the front post-processing unit 6 at a second fold position different from the first fold position. The first sheet folding unit 16 is disposed upstream of the second sheet folding unit 17 in the sheet conveying direction. For this reason, when the sheet folding mechanism 20 performs folding processing on the sheet, the second sheet folding section 17 is moved to the second fold position after the first sheet folding section 16 has folded the sheet at the first fold position. Fold the sheet.

  The post-stage post-processing unit 7 includes a post-processing mechanism 18 that performs post-processing other than folding processing on the sheet fed from the pre-stage post-processing unit 6, and a discharge roll (not shown) that discharges the sheet to the sheet stacking tray 19. (Sheet discharge means). The post-processing mechanism 18 performs, for example, stapling (binding) or punching (punching) as post-processing other than folding. In the staple processing, a plurality of sheets are bound by driving a staple. The staple processing includes a single staple mode in which the position (staple processing position) at which the staple needle is driven into the sheet is set at one sheet corner on the front side or the rear side, and a dual staple mode set at two positions along the sheet edge. . Further, in the single staple mode, there are parallel strikes in which the staples are driven in parallel to the sheet edge, and diagonal strikes in which the staple is driven in an oblique direction (usually 45 degrees) with respect to the sheet edge. is there. In the punching process, holes are made in the sheet by punching.

  The sheet stacking tray 19 is a tray from which the sheet conveyed in the post-processing apparatus main body 3 is finally discharged (stacked). The sheet stacking tray 19 is provided on one side of the post-stage post-processing unit 7 so as to be lifted and lowered. The raising / lowering operation of the sheet stacking tray 19 is controlled according to the stacking height of the sheets discharged to the sheet stacking tray 19. The sheet discharged to the sheet stacking tray 19 becomes a sheet that has been post-processed as necessary by the pre-stage post-processing unit 6 and the post-stage post-processing unit 7 in accordance with an instruction from the user.

  FIG. 2 is a diagram illustrating a specific configuration example of the pre-stage post-processing unit 6 including the sheet folding mechanism 20. The pre-stage post-processing unit 6 includes a first sheet conveyance path R1, a second sheet conveyance path R2, a third sheet conveyance path R3, and a fourth sheet conveyance path R4. The first sheet conveyance path R1 is formed in a substantially horizontal state (on a straight line). The second sheet transport path R2 is formed to branch downward from the middle of the first sheet transport path R1 near the entrance. The third sheet conveyance path R3 is formed so as to branch further downward from the middle of the second sheet conveyance path R2. The fourth sheet conveyance path R4 is formed to branch upward from the middle of the third sheet conveyance path R3. Further, the terminal portion of the fourth sheet conveyance path R4 joins in the middle of the exit of the first sheet conveyance path R1.

  In the first sheet conveyance path R1, a conveyance roll 23, a switching gate 24, and a conveyance roll 25 are sequentially provided from the upstream side to the downstream side in the sheet conveyance direction. The conveyance rolls 23 and 25 convey the sheet while nipping at each position. The switching gate 24 switches the traveling direction of the sheet at a branch portion between the first sheet conveying path R1 and the second sheet conveying path R2. The switching gate 24 is turned on and off by, for example, a driving means (solenoid or the like) (not shown). When the switching gate 24 is turned on, the branching portion guides the sheet traveling direction toward the second sheet conveyance path R2, and when the switching gate 24 is turned off, the branching portion. Then, the sheet traveling direction is guided to the first sheet conveyance path R1 side. Therefore, when the switching gate 24 is turned on, the sheet sent from the connecting unit 5 to the pre-stage post-processing unit 6 is guided from the first sheet transport path R1 to the second sheet transport path R2. Further, when the switching gate 24 is turned off, the sheet fed from the connecting unit 5 to the preceding post-processing unit 6 is transported horizontally along the first sheet transport path R1.

  In the second sheet conveying path R, a push roll 26 and a stopper 27 are sequentially provided from the upstream side to the downstream side in the sheet conveying direction. The pushing roll 26 pushes the sheet in one direction while nipping the sheet in the second sheet conveying path R2. The stopper 27 regulates the end of movement of the sheet by abutting against the leading edge of the sheet in the second sheet conveyance path R2. The stopper 27 is provided so as to be movable in the sheet conveyance direction on the second sheet conveyance path R <b> 2 so that the fold position of the sheet can be adjusted (variable) according to the sheet size and the like.

  In the third sheet conveyance path R3, a folding roll 28, a pushing roll 29, and a stopper 30 are provided in this order from the upstream side to the downstream side in the sheet conveyance direction. The folding roll 28 folds the sheet in the third sheet conveyance path R3. The push roll 29 pushes the sheet in one direction in the third sheet conveyance path R3. The stopper 30 regulates the end of movement of the sheet by abutting against the leading edge of the sheet in the third sheet conveyance path R3. The stopper 30 is provided so as to be movable in the sheet conveyance direction on the third sheet conveyance path R3 so that the position of the sheet crease can be adjusted (variable) according to the sheet size and the like.

  In the fourth sheet conveyance path R4, a folding roll 31 and conveyance rolls 32-34 are provided in order from the upstream side to the downstream side in the sheet conveyance direction. The folding roll 31 folds the sheet in the fourth sheet conveyance path R4. The conveyance rolls 32 to 34 convey the sheet while nipping at each position.

  In the pre-stage post-processing unit 6 having the above-described configuration, the first sheet folding unit 16 is configured using a pressing roll 26, a stopper 27, and a folding roll 28, and the second sheet folding unit 17 is configured with a pressing roll 29. The stopper 30 and the folding roll 31 are used. Sheets that are not subject to folding processing are conveyed substantially horizontally (straight) along the first sheet conveyance path R1, while sheets that are subject to folding processing (Z-folding) Is sent from the sheet transport path R1 to the second sheet transport path R2 by the switching gate 24, and then passes through the third sheet transport path R3 and the fourth sheet transport path R4 in order, and then the first sheet transport path R1. It is supposed to be returned to.

  The sheet sent to the second sheet conveyance path R2 by the switching gate 24 is folded in the following procedure. First, the sheet is pushed in by the pushing roll 26 in a state where the leading edge of the sheet is abutted against the stopper 27 in the second sheet conveying path R2, thereby deforming (buckling) the sheet in a loop shape in the space near the folding roll 28. At the same time, the sheet is folded at the first fold position as shown in FIG.

  Next, the sheet folded by the folding roll 28 is conveyed while being nipped by the pushing roll 29, so that the leading edge of the sheet abuts against the stopper 30 in the third sheet conveyance path R3 as shown in FIG. 3B. . Further, by pushing the sheet with the pushing roll 26 from this state, the sheet is deformed into a loop shape in the space near the folding roll 31, and the loop portion is drawn with the folding roll 31 and niped, whereby FIG. ) Fold the sheet at the second fold position.

  In this case, in the first sheet folding portion 16, the first fold position is set to a quarter of the original sheet length from the leading edge of the sheet that has hit the stopper 27, and the second sheet folding portion 17 is set. In this case, by setting the second crease position to a quarter of the original sheet length from the leading end (first crease) of the sheet that hits the stopper 30, the first crease is moved from the sheet end to the original position. The quarter of the sheet length and the second crease are made from the sheet edge to a half of the original sheet length. As a result, the sheet that is Z-folded by half the original sheet length is discharged from the folding roll 31 as shown in FIG. The Z-folded sheet is returned to the first sheet conveyance path R1 through the fourth sheet conveyance path R4. Therefore, when a sheet (Z-folded sheet) that has been Z-folded by the front-stage post-processing unit 6 is sent to the rear-stage post-processing unit 7, the Z-folded sheet is sent out with the folded portion of the Z-folded sheet facing downstream in the sheet conveyance direction. The Z-folded sheet is sent out in a state where the folded portion of the Z-folded sheet faces downward (downward state).

  FIG. 4 is a diagram illustrating a configuration example of the sheet discharge portion of the post-stage post-processing unit 7. First, in FIG. 4A, the sheet stacking tray 19 is provided so as to extend obliquely upward from the side wall portion of the post-processing apparatus main body 3. The sheet stacking tray 19 is disposed in a state where the main surface 19A of the tray is inclined at a predetermined angle θ1 (for example, θ1≈45 degrees) with respect to the horizontal plane. On the other hand, the discharge roll 35 serving as a sheet discharge unit discharges the sheet toward the sheet stacking tray 19 by rotating while nipping the sheet between the pair of rolls. When the post-processing apparatus main body 3 is viewed from the front (front side), the sheet discharge direction by the discharge roll 35 is inclined in the same direction as the sheet stacking tray (sheet main surface) 19 (in the illustrated example, right upward). . However, the inclination angle θ2 in the sheet discharge direction with respect to the horizontal plane is set smaller than the predetermined angle θ1 (for example, set to θ1≈30 degrees).

  Further, the sheet stacking tray 19 includes a tray body 191 and a movable tray 192. The posture (orientation) of the tray main body 191 is fixed so that the main surface 19A of the tray is always inclined at the same angle θ1 with respect to the horizontal plane. The movable tray 192 is provided at the end of the tray on the apparatus main body 3 side. In addition, the tray main body 191 and the movable tray 192 are connected by a rotation support part 193. The rotation support part 193 is a part that supports the movable tray part 192 so as to be rotatable. The posture (orientation) of the movable tray portion 192 is changed to an inclined posture along the main surface 19A of the tray as shown in FIG. 4 (A) and a horizontal surface as shown in FIG. It can be changed between horizontal postures. The elliptical cam 36 receives and supports the movable tray portion 192 from below, and changes the posture of the movable tray portion 192 by rotating in one direction and the other direction within a preset angle range.

  A stack sensor 37 is provided in the vicinity of the discharge roll 35. The stack sensor 37 outputs a detection signal when the stack height of the sheets discharged to the sheet stacking tray 19 by the discharge roll 35 reaches a predetermined height. More specifically, the detection point of the stack sensor 37 is set at a position slightly lower than the sheet discharge port along the side wall of the post-processing apparatus main body 3 where the trailing edge of the sheet discharged to the sheet stacking tray 19 is abutted. ing. When a large number of sheets are discharged to the sheet stacking tray 19, the trailing edge of the sheets gradually accumulates along the side wall of the post-processing device 3 and reaches the detection point of the stack sensor 37. The stack sensor 37 is configured to output a detection signal.

  Further, when the post-processing apparatus main body 3 is viewed in plan, the sheet stacking tray 19 is provided so as to be movable in a direction perpendicular to the sheet discharge direction (right arrow direction) by the discharge roll 35 as shown in FIG. ing. The movement of the sheet stacking tray 19 is performed in order to shift the position of the sheet discharged to the sheet stacking tray 19 in a direction orthogonal to the sheet discharging direction. The position where the sheet stacking tray 19 can be moved in the direction orthogonal to the sheet discharge direction is, for example, based on one side edge position of the sheet stacking tray 19 as a reference from the rear side R of the post-processing apparatus main body 3 to the front side. Toward F, there are a first tray position P1, a second tray position P2, and a third tray position P3. The first tray position P1 is set to the most rear side R. The second tray position P2 is set at a position shifted from the first tray position P1 to the front side F by a certain amount. The third tray position P3 is set at a position shifted from the second tray position P2 by a certain amount toward the front side F.

  FIG. 6 is a block diagram showing a schematic configuration example of a part of the apparatus control system. In the figure, the control unit 38 mainly controls the operation of the post-processing apparatus. In addition to the switching gate 24, the sheet folding mechanism 20, the post-processing mechanism 18, and the stack sensor 37, the control unit 38 is connected to a discharge motor 39, a tray lifting / lowering motor 40, a posture changing motor 41, and a shift motor 42. Yes. Here, it is assumed that the post-processing mechanism 18 includes a staple processing mechanism. This staple processing mechanism binds a bundle of sheets by driving staples at the trailing edge of a sheet in a single staple mode or a dual staple mode. The rear end portion of the sheet refers to an end portion of the sheet that is arranged facing the upstream side in the sheet conveying direction. Therefore, when the sheet is discharged by the discharge roll 35, the leading end portion of the sheet passes through the discharge roll 35 before the trailing end portion of the sheet and is sent out to the sheet stacking tray 19 side.

  The discharge motor 39 is a drive source that rotationally drives the discharge roll 35 described above. The tray lifting / lowering motor 40 is a drive source for lifting / lowering the sheet stacking tray 19. The drive of the tray lifting / lowering motor 40 is controlled based on the detection signal of the stack sensor 37. That is, each time the stack sensor 37 outputs a detection signal, the control unit 38 drives the tray lifting / lowering motor 49 to lower the sheet stacking tray 19 by a certain amount. However, the upper and lower limit positions of the sheet stacking tray 19 are regulated by a pair of upper and lower limit sensors (not shown). Therefore, the sheet stacking tray 19 starts to descend from the upper limit position by driving the tray lifting / lowering motor 40 and descends to the lower limit position as necessary. The posture changing motor 41 is a drive source for rotating the elliptical cam 36 to change the posture of the movable tray unit 192 from the inclined posture to the horizontal posture or from the horizontal posture to the inclined posture.

  The shift motor 42 serves as a drive source for moving the sheet stacking tray 19 in order to shift the position of the sheets discharged to the sheet stacking tray 19 in a direction orthogonal to the sheet discharging direction. The sheet shift mode using the shift motor 42 includes a 3-position shift mode and a 2-position shift mode. The 3-position shift mode is a shift mode in which the position of the sheet discharged to the sheet stacking tray 19 is sequentially shifted between the first position, the second position, and the third position. On the other hand, the two-position shift mode is a shift mode in which the position of the sheet discharged to the sheet stacking tray 19 is alternately shifted between the first position and the third position.

  Here, the above-mentioned first position refers to the position of the sheet discharged in a state where the sheet stacking tray 19 is moved to the first tray position P1 (see FIG. 5). The second position refers to the position of the sheet discharged in a state where the sheet stacking tray 19 is moved to the second tray position P2, and the third position refers to the sheet stacking tray 19 in the third tray. This refers to the position of the sheet that is ejected in the state moved to the position P3. Therefore, on the sheet stacking tray 19, the first position is the position closest to the front side F in the direction orthogonal to the sheet discharge direction. In addition, the second position is shifted from the first position to one (rear side R) by a certain amount, and the third position is shifted from the second position to one (rear side R) by a certain amount. It becomes the position.

  FIG. 7 is a flowchart applied to the operation control of the pre-stage post-processing unit 6 including the sheet folding mechanism 20. First, when a job including a sheet folding process (for example, a copy job or a print job) is started, a sheet (current sheet) sent from the connecting unit 5 to the preceding post-processing unit 6 is Z-folded (folding process). ) Is determined (step S1). If the sheet is to be Z-folded, the sheet conveyed by the conveying roll 23 is guided from the first sheet conveying path R1 to the second sheet conveying path R2 by turning on the switching gate 24. (Step S2).

  Next, the sheet is folded at the first fold position by operating the first sheet folding section 16 (step S3). Next, the sheet is folded at the second fold position by operating the second sheet folding unit 17 (step S4). The sheet is Z-folded by such a two-stage folding operation. Further, the Z-folded sheet is returned to the first sheet conveyance path R1 through the fourth sheet conveyance path R4.

  Thereafter, it is confirmed whether or not there is a next sheet (step S5). If there is a next sheet, the process returns to step S1. If the sheet is not the target of Z-folding in step S1, the first sheet is conveyed by the upstream conveying roll 23 and the downstream conveying roll 25 by turning off the switching gate 24. It is transported horizontally along the path R1 (step S6). In this case, the sheet is sent to the post-stage post-processing unit 7 without being Z-folded (folded) by the pre-stage post-processing unit 6.

  FIGS. 8 and 9 are flowcharts applied to the operation control of the movable tray 192 of the sheet stacking tray 19. First, when a job including sheet folding processing (for example, a copy job, a print job, etc.) is started, the value of the variable m is initialized (m = 1) (step S11), and then the post-processing unit 7 in the subsequent stage. It is determined whether or not the sheet discharged to the sheet stacking tray 19 is a target of Z-folding (folding processing), that is, whether or not the discharged sheet is a Z-folded sheet (step S12). If it is a Z-folded sheet, the value of m is incremented by 1 (step S13). Thus, the value of m becomes a count value indicating the number of discharged sheets that are Z-folded by the sheet folding mechanism 20 and discharged to the sheet stacking tray 19 by the discharge roll 35.

  Subsequently, it is determined whether or not the movable tray 192 is in an inclined posture (step S14). If it is in the inclined posture, it is confirmed whether or not the value of the posture change flag is set to “0” (step S15). The value of the posture change flag is set to either “0” or “1”. Incidentally, when the job is started, the posture of the movable tray unit 192 is inclined, and the value of the posture change flag is set to “0”.

  When the value of the attitude change flag is set to “0”, it is determined whether or not the value of m has reached a predetermined value J (step S16). When the condition of m = J is satisfied, the posture changing motor 41 is driven to rotate the elliptical cam 36, thereby changing the posture of the movable tray 192 from the inclined posture to the horizontal posture (step S17).

  Thereafter, it is confirmed whether or not there is a next sheet (step S18), and if there is a next sheet, the process returns to step S12. If the sheet is not a Z-fold target in step S12, or if the value of m has not reached the predetermined value J in step S16, the process proceeds to step S18.

  On the other hand, when the posture of the movable tray unit 192 is not in the tilted posture in Step S14 (when it is in the horizontal posture), or when the value of the posture change flag is not set to “0” in Step S15 (“ If “1” is set), it is determined whether or not the value of m has reached the upper limit value K (step S19). The upper limit value K is set according to the maximum allowable number of Z-folded sheets that can be stacked on the sheet stacking tray 19. Therefore, the magnitude relationship between the predetermined value J and the upper limit value K is J <K.

  When the value of m reaches the upper limit value K, since the sheet cannot be discharged thereafter, the user is notified that the sheets are loaded on the sheet stacking tray 19 by displaying a message on the operation panel, for example. Then, the device operation is stopped (step S24). On the other hand, if the value of m has not reached the upper limit K, it is confirmed whether or not a detection signal is output from the stack sensor 37 (step S20). If no detection signal is output from the stack sensor 37, the process proceeds to step S18.

  On the other hand, when the detection signal is output from the stack sensor 37, it is determined whether or not the value of m is equal to or less than the threshold value T (step S21). The threshold value T is set to a value larger than the predetermined value J and smaller than the upper limit value K. For example, the predetermined value J = 10, the upper limit value K = 100, and the threshold value T = 30 are set.

  If the value of m exceeds the threshold value T, the process proceeds to step S24. If the value of m is equal to or less than the threshold value T, the posture of the movable tray 192 is returned from the horizontal posture to the tilted posture by driving the posture changing motor 41 and rotating the elliptical cam 36 (step S22). Next, after the value of the posture change flag is set to “1” (step S23), the process proceeds to step S18.

  As described above, in the image forming apparatus 1 according to the embodiment of the present invention, when the number of Z-folded sheets discharged to the sheet stacking tray 19 reaches the predetermined value J, the movable tray unit is driven by the attitude change motor 41. The posture of 192 is changed from the inclined posture to the horizontal posture. For this reason, when executing a job including sheet folding processing, the timing for changing the posture of the movable tray 192 from the inclined posture to the horizontal posture is set to the number of discharged Z-folded sheets (setting of a predetermined value J). Based on this, it can be controlled appropriately.

  Therefore, for example, when the stacking form of the entire sheet swells in a mountain shape as shown in FIG. 10A when the same number of Z-folded sheets as the predetermined value J are discharged to the sheet stacking tray 19, By changing the posture of the movable tray 192 from the inclined posture to the horizontal posture, as shown in FIG. 10 (B), the rear end side of the sheet is lifted by the movable tray portion 192 so that the entire sheet is recessed like a bow. Deforms (warps). Therefore, the bulge of the mountain shape that has occurred up to that point is eliminated, and the sheet stacking height can be kept low. For this reason, the vicinity of the sheet discharge opening can be greatly opened, and the sheet can be prevented from falling into the sheet discharge opening. Thereby, more Z-fold sheets can be stacked on the sheet stacking tray 19 in one job while effectively preventing the stacking failure of Z-fold sheets. In addition, since the movable tray 192 does not tilt in the direction opposite to the main surface 19A of the sheet stacking tray 19, it is possible to effectively prevent stacking defects when discharging sheets other than Z-folding.

  Further, in the image forming apparatus 1 described above, the detection signal is output from the stack sensor 37 in a state where the sheet stacking tray 19 is lowered to the lower limit position after the posture of the movable tray unit 192 is changed from the inclined posture to the horizontal posture. In this case, if the number of ejected Z-fold sheets m at that time is equal to or less than the threshold value T, the posture of the movable tray 192 is returned from the horizontal posture to the inclined posture. This is because, in a situation where the ratio of the Z-folded sheet occupying all the sheets discharged to the sheet stacking tray 19 is small, the demerit caused by changing the attitude of the movable tray portion 192 to the horizontal attitude is caused. This is because is larger. That is, when the movable tray 192 is changed from the inclined posture to the horizontal posture, the rear end side of the sheet is lifted by the movable tray portion 192. For example, when it is assumed that sheets that are not Z-folded are continuously discharged, the stack sensor The number of discharged sheets when 37 outputs a detection signal is greater when the movable tray 192 is in the inclined posture than in the horizontal posture. Therefore, in a situation where the number of Z-folded sheets to be discharged is small, more sheets can be discharged to the sheet stacking tray 19 by returning the movable tray portion 192 to the inclined posture.

  Further, the sheet shift mode may be changed as the posture of the movable tray portion 192 is changed from the inclined posture to the horizontal posture. Specifically, in a job including stapling processing, when the stapling processing position is set at one sheet corner, that is, when the single stapling mode is applied, the posture of the movable tray unit 192 is changed in step S17. The seat posture is changed from the tilt posture to the horizontal posture, and the seat shift mode is changed from the 3-position shift mode to the 2-position shift mode.

  Here, when the sheet shift mode is not changed, the sheet bundle in which the staples are driven into one sheet corner is sequentially discharged in the three-position shift mode. For this reason, as shown in FIG. 11A, the sheet bundle Sp2 discharged at the second position is superimposed on the sheet bundle Sp1 discharged at the first position. Further, the sheet bundle Sp3 discharged at the third position is overlaid on the sheet bundle Sp2 discharged at the second position, and the first bundle of sheets discharged at the third position is stacked on the first sheet bundle Sp3. The sheet bundle Sp1 discharged at the position is overlapped. In such a case, when the sheet bundle Sp1 is discharged at the first position, the sheet bundle Sp1 may be caught by the staples of the sheet bundle Sp3 discharged before at the third position, and at the second position. When the sheet bundle Sp2 is discharged, the sheet bundle Sp2 may be caught by the staple needle of the sheet bundle Sp1 discharged before at the first position, and when the sheet bundle Sp3 is discharged at the third position. The sheet bundle Sp3 may be caught by the staples of the sheet bundle Sp2 discharged at the second position before that. In other words, when a sheet is discharged at any of the first position, the second position, and the third position, the sheet bundle that is discharged this time may be caught by the staple needle of the previously discharged sheet bundle. In order to prevent such catching of the sheet bundle, a sufficiently large sheet shift amount is ensured between the first position and the second position and between the second position and the third position. It is effective. However, in consideration of the appearance when the sheet bundles are stacked and the delay of the shift operation with respect to the sheet discharge timing, it is not realistic to increase the sheet shift amount.

  On the other hand, when the sheet shift mode is changed, the sheet bundle in which the staple is driven at one sheet corner in the two-position shift mode is sequentially discharged. Therefore, as shown in FIG. 11B, the sheet bundle Sp3 discharged at the third position is overlaid on the sheet bundle Sp1 discharged at the first position, and discharged at the third position. The sheet bundle Sp1 discharged at the first position is overlaid on the sheet bundle Sp3. In such a case, when the sheet bundle Sp1 is discharged at the first position, the sheet bundle Sp1 may be caught on the staple needles of the sheet bundle Sp3 discharged at the third position before, but the third position. When the sheet bundle Sp3 is discharged at this time, a sufficient shift amount is secured between the sheet bundle Sp1 and the sheet bundle Sp3, so that the sheet bundle Sp3 discharged this time is discharged at the first position before that. There is no fear of being caught by the staple needle of Sp1. Therefore, it is possible to reduce the chance that the sheet bundle is caught by the staples without increasing the sheet shift amount.

  Further, when the posture of the movable tray portion 192 is changed from the inclined posture to the horizontal posture, as shown in FIG. 12, the entire stacked sheets are deformed so as to be recessed in a bow shape, so that the outside of the sheet discharge port near the discharge roll 35 ( A large hollow space (valley) is formed outside the machine. On the other hand, since the Z-fold sheet is discharged with the folding portion at the leading end side, the Z-fold sheet is folded when an attempt is made to discharge the Z-fold sheet by the discharge roll 35 in a situation where a wide hollow space as shown in the figure is formed. The front end side of the sheet easily falls into the hollow space due to the weight of the portion. When the leading end side of the sheet actually falls into the hollow space, the entire Z-folded sheet is curved in a U-shape, so that the stacked state cannot be discharged as it is without discharging the Z-folded sheet as it is.

  Therefore, in the present embodiment, when the posture of the movable tray unit 192 is changed, the discharge speed of the sheet folded (Z-folded) by the sheet folding mechanism 20 is changed. The sheet discharge speed can be changed for each sheet by adjusting the rotation speed of a discharge motor 38 that is a rotation drive source of the discharge roll 35. Therefore, the sheet discharge speed is changed by the discharge motor 39 in accordance with a speed change instruction from the control unit 38.

  Specifically, the discharge speed of the sheet applied to the Z-folded sheet when the movable tray unit 192 is in the inclined posture is set to V1, and the discharge of the sheet applied to the Z-folded sheet when the movable tray unit 192 is in the horizontal posture. When the speed is V2, the sheet discharge speed is changed in a relationship of V1 <V2. That is, when the posture of the movable tray 192 is changed from the inclined posture to the horizontal posture, the sheet discharge speed applied to the Z-folded sheet is changed from V1 to V2 higher than that. By increasing the sheet discharge speed in this way, the entire sheet can be discharged before the leading end side of the Z-folded sheet falls. Further, when the posture of the movable tray unit 192 is returned from the horizontal posture to the inclined posture, the sheet discharge speed applied to the Z-folded sheet may be changed from V2 to V1 that is slower than that. It is desirable to set the speed ratio between the sheet discharge speeds V1 and V2, for example, in a relationship of V2≈1.3V1. In addition, if the sheet discharge speed is increased too much, the sheet discharged at a higher discharge speed may jump over the previously discharged sheet and collapse the stacking state. It is important to increase the discharge speed of the Z-folded sheet.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus to which the present invention is applied. It is a figure which shows the specific structural example of a front | former stage post-processing unit. It is a figure which shows the procedure of sheet folding operation | movement. It is a figure which shows the structural example of the sheet | seat discharge | emission part of a back | latter stage post-processing unit. FIG. 6 is a diagram illustrating a sheet stacking tray shift operation. It is a block diagram which shows the schematic structural example of a part of apparatus control system. It is a flowchart applied to operation control of a front stage post-processing unit. 6 is a flowchart (part 1) applied to operation control of a movable tray portion of a sheet stacking tray. 10 is a flowchart (No. 2) applied to the operation control of the movable tray portion of the sheet stacking tray. It is a figure which shows the attitude | position change of a movable tray part, and the change of the sheet | seat stacking form accompanying this. It is a figure explaining the predominance by change of a shift mode. It is a figure which shows the malfunction which may occur when the discharge speed of a sheet | seat is insufficient. It is a figure explaining Z folding. It is a figure for demonstrating the subject of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming apparatus main body, 3 ... Post-processing apparatus main body, 4 ... Image forming unit, 5 ... Connection unit, 6 ... Pre-stage post-processing unit, 7 ... Post-stage post-processing unit, 16 ... 1st Sheet folding portion, 17 ... second sheet folding portion, 19 ... sheet stacking tray, 19A ... main surface, 20 ... sheet folding mechanism, 24 ... switching gate, 35 ... discharge roll, 36 ... elliptical cam, 37 ... stack sensor ( Detection means), 38 ... control section, 39 ... discharge motor, 41 ... attitude changing motor, 42 ... shift motor, 192 ... movable tray section

Claims (3)

The tray main body provided in the apparatus main body with the main surface inclined, the movable tray provided at the tray end on the apparatus main body, the tray main body, and the movable tray connected to each other to connect the movable body A sheet stacking tray having a rotation support portion that rotatably supports the tray portion;
Posture changing means for driving to change the posture of the movable tray portion between an inclined posture along the main surface of the tray main body portion and a horizontal posture along a horizontal plane;
Sheet discharge means for discharging sheets to the sheet stacking tray;
Sheet folding means for performing Z-folding as a folding process on the sheet before being discharged to the sheet stacking tray;
Count the number of sheets discharged from the sheet folding means to the sheet stacking tray by the sheet discharge means, and when the counted value reaches a predetermined value, drive the posture changing means. Control means for controlling the posture of the movable tray portion to change from the tilted posture to the horizontal posture , wherein the ratio of the Z-folded sheet to the total sheets discharged to the sheet stacking tray by the sheet discharging means And a control unit that controls the posture of the movable tray unit to change from the inclined posture to the horizontal posture . Shifting the position of the sheet discharged to the sheet stacking tray in a direction perpendicular to the sheet discharging direction, and a sheet shift mode as the posture of the movable tray portion is changed from the inclined posture to the horizontal posture. Shift means for changing
The shift means includes a first position, a second position shifted from the first position to one side, and a third position shifted from the second position to one side. And a two-position shift mode in which the first position and the third position are alternately shifted. The position of the movable tray section is changed from the inclined position to the horizontal position. 2. The post-processing apparatus according to claim 1, wherein the tray shift mode is changed from the three-position shift mode to the two-position shift mode. An image forming apparatus comprising: a post-processing apparatus according to claim 1 or 2, wherein.

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