JP2009120331A - Sheet stacking device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet stacking device and an image forming device capable of shortening the time required for switching a stacking position of a bundle of sheets. <P>SOLUTION: First and second auxiliary alignment member 21, 31 are provided on side surfaces abutted on the sheet of first and second alignment members 20, 30 for aligning a position in a width direction of the delivered sheet movably in a vertical direction. When the first alignment member 20 is positioned at a first reference position, the first auxiliary alignment member 21 is moved to an abutting position for pressing the bundle of sheets and abutted on the sheet moved accompanying with movement of the second alignment member 30. Further, when the second alignment member 30 is positioned at a second reference position, the second auxiliary alignment member 31 is moved to an abutting position for pressing the bundle of sheets and abutted on the sheet moved accompanying with movement of the first alignment member 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sheet stacking apparatus and an image forming apparatus, and more particularly to a sheet stacking sheet discharged from a main body of an image forming apparatus at high speed with high accuracy.

  2. Description of the Related Art In recent years, in image forming apparatuses that form images on sheets, the speed of image formation has been increased due to technological advances, and the discharge of sheets discharged from the main body of the image forming apparatus as the speed of image formation increases. The speed is also increasing. In order to arrange and stack a large number of sheets discharged at such a high speed as described above, a conventional image forming apparatus includes, for example, a large-capacity stacker device as a sheet stacking device (see Patent Document 1). .

  FIG. 9 shows the configuration of such a conventional large-capacity stacker apparatus. This stacker device is provided with a gripper 503 that is attached to a conveyance belt 508 that rotates clockwise and moves integrally with the conveyance belt 508 while holding the leading edge of the sheet, thereby conveying the sheet. Further, a front end pressing member 506 and a rear end pressing member 507 that press the front end portion and the rear end portion of the sheets stacked on the sheet stacking table 505 are provided.

  In the stacker apparatus having such a configuration, the sheet discharged from the image forming apparatus main body (not shown) is received by the entrance roller 511, and then the leading end of the sheet is transferred to the gripper 503 by the conveyance roller 502. Thereafter, the conveyance belt 508 rotates, and accordingly, the gripper 503 moves together with the conveyance belt 508 while holding the leading end of the sheet together with the conveyance belt 508, so that the sheet moves along the upper side of the sheet stacking table 505. Be transported.

  Thereafter, when the leading edge of the sheet collides with the leading edge stopper 504, the holding by the gripper 503 is released, and the sheet falls onto the sheet stacking table 505, and a predetermined number of sheets are stacked. Each time the sheets are stacked in this way, a jogging process is performed by aligning means (not shown) so as to align the sheet end in the direction (hereinafter referred to as the width direction) perpendicular to the sheet conveyance direction (sheet discharge direction). This improves the alignment of the sheets.

  By the way, as such a conventional stacker device, there is one that performs shift stacking in which a sheet bundle is shifted in the width direction and stacked on a stacking tray (sheet mounting table) (see Patent Document 2). Next, a shift stacking method of such a conventional stacker apparatus will be described with reference to FIGS. In FIGS. 10 and 11, 18 is a stacking tray, and 39 and 40 are width alignment means.

  When the sheets P11 are stacked on the stacking tray 18 as shown in FIG. 10A, first, the first width aligning means 39 moves to a predetermined reference position. After that, as shown in FIGS. 10B and 10C, every time the sheet P11 is discharged, the second width aligning means 40 reciprocates in the direction of the first width aligning means 39, and the stacked sheets P11. Align the position in the width direction.

  Next, when the stacking of one bundle of sheets P11 is completed, the first and second width aligning means 39 and 40 are retracted for shift stacking as shown in FIG. However, the upper end of the already stacked sheet bundle moves to a position below the lower end of the width aligning means 39, 40. Thereafter, as shown in FIG. 10 (e), the second width aligning means 40 moves to a shift position that is a reference for the shift position of the next bundle, and the upper end of the already stacked sheet bundle contacts the second width aligning means 40. The stacking tray 18 is raised to the position where it is placed.

  Next, when the discharge of the sheet is resumed, the first width aligning means 39 is changed to the second width aligning means 40 every time the sheet P12 is discharged as shown in FIG. 10 (f) and FIG. 11 (a). And reciprocatingly move the stacked sheets P12 to align them. When the stacking of the sheets P12 for two bundles is completed, the first and second width aligning means 39 and 40 are retracted as shown in FIG. Moves to a position below the lower ends of the first and second width aligning means 39, 40.

  Thereafter, as shown in FIG. 11C, the first width aligning means 39 moves to a shift position which becomes a reference of the shift position of the next bundle, and the upper end of the already stacked sheet bundle comes into contact with the first width aligning means 39. The stacking tray 18 is raised to the position where it is placed. Thereafter, the sheet bundle is sequentially stacked in this manner, thereby stacking the sheet bundle while ensuring the alignment of the plurality of sheet bundles.

JP 2006-124052 A JP 2006-21874 A

  However, in such a conventional sheet stacking apparatus (stacker apparatus) and image forming apparatus, when the stack of sheets is shifted and stacked in the width direction, the width aligning means 39 and 40 are first retracted in order to change the stacking position. After this, the stacking tray 18 must be lowered. Thereafter, one of the width aligning means 39, 40 is moved to the shift position so that it becomes a reference for the next sheet bundle, and the stacking tray 18 is further moved to a position where the width aligning means 39, 40 and the upper end of the already stacked sheet bundle come into contact. Must be raised.

  During the series of operations for switching the stacking position of the sheet bundle, since the next bundle of sheets cannot be discharged, the time required for switching the stacking position of the sheet bundle becomes long. It cannot cope with the high-speed image formation of the apparatus.

  Therefore, the present invention has been made in view of such a situation, and an object of the present invention is to provide a sheet stacking apparatus and an image forming apparatus that can shorten the time required for switching the stacking position of sheet bundles. It is.

  The present invention provides a first alignment member and a second alignment member, which are provided so as to be movable in a width direction perpendicular to the sheet discharge direction and align the positions of the sheets discharged to the sheet stack portion in the width direction. When stacking other sheet bundles on the aligned sheet bundle while shifting in the width direction, the second alignment member is directed toward the first alignment member at the first reference position. In the sheet stacking apparatus that moves the first alignment member toward the second alignment member moved to the second reference position and shifts and stacks the other sheet bundle after aligning the sheet bundle by moving, When the first alignment member is in the first reference position, the first alignment member moves with the movement of the second alignment member. Move to the abutting position where it hits the sheet When the second alignment member is at the second reference position, the auxiliary alignment member is provided on a side surface of the second alignment member that is in contact with the sheet of the second alignment member. And a second auxiliary alignment member that moves to a contact position that abuts against the sheet that moves with the movement.

  According to the present invention, the stacking position of the sheet bundle is switched by moving one of the auxiliary alignment members provided on the first and second alignment members downward, so that the stacking position of the sheet bundle is The time required for switching can be shortened.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a sheet stacking apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 900 denotes an image forming apparatus, and reference numeral 901 denotes an image forming apparatus main body. The image forming apparatus main body 901 is provided with an image reading apparatus 951 including a scanner unit 955 and an image sensor 954, an image forming unit 902 that forms an image on a sheet, a double-sided device 953, a platen glass 952, and the like. A document feeder 950 for feeding a document to the platen glass 952 is provided on the upper surface of the image forming apparatus main body 901.

  The image forming unit 902 includes a cylindrical photosensitive drum 906, a charger 907, a developing unit 909, a cleaning device 913, and the like. Further, a fixing device 912 and a discharge roller pair are provided on the downstream side of the image forming unit 902. 914 etc. are arranged. Further, the image forming apparatus main body 901 is connected to a stacker 100 which is a sheet stacking apparatus for stacking sheets on which image formation has been performed after image formation from the image forming apparatus main body 901. Reference numeral 960 denotes a control unit that controls the image forming apparatus main body 901 and the stacker 100.

  Next, an image forming operation of the image forming apparatus main body 901 having such a configuration will be described.

  When an image forming signal is output from the control unit 960, a document is first placed on the platen glass 952 by the document feeder 950, and the document image is read by the image reading device 951. The read digital data is exposed. Input to means 908. The exposure unit 908 irradiates the photosensitive drum 906 with light corresponding to the digital data.

  At this time, the surface of the photosensitive drum 906 is uniformly charged by the charger 907. When light is irradiated in this manner, an electrostatic latent image is formed on the surface of the photosensitive drum, and the electrostatic latent image is developed. By developing with the device 909, a toner image is formed on the surface of the photosensitive drum.

  On the other hand, when a paper feed signal is output from the control unit 960, the sheet P set in the cassettes 902a to 902e is first transported to the registration roller 910 by the paper feed rollers 903a to 903e and the transport roller pair 904.

  Next, the sheet P is conveyed by a registration roller 910 to a transfer unit including a charger 905 at a timing such that the leading edge of the sheet and the leading edge of the toner image on the photosensitive drum 906 are aligned. In this transfer portion, a transfer bias is applied to the sheet S by the charger 905, whereby the toner image on the photosensitive drum 906 is transferred to the sheet side.

  Next, the sheet P on which the toner image is transferred is conveyed to the fixing device 912 by the conveying belt 911, and then the toner image is heat-fixed when nipped and conveyed between the heating roller and the pressure roller of the fixing device 912. The At this time, foreign matters such as residual toner that are not transferred to the sheet on the photosensitive drum 906 are scraped off by the blade of the cleaning device 913. As a result, the surface of the photosensitive drum 906 becomes clear, and the next It can prepare for image formation.

  The fixed sheet is conveyed as it is to the stacker 100 which is a sheet stacking device by the discharge roller pair 914 or is conveyed to the double-sided device 953 by the flapper 915, and the image forming surface is reversed and image formation is performed again. It will be.

  FIG. 2 is a block diagram illustrating a configuration of the control unit 960. The control unit 960 includes a CPU circuit unit 150, and the CPU circuit unit 150 incorporates a CPU, a ROM 151, and a RAM 152 (not shown). Then, according to the control program stored in the ROM 151, the document feed control unit 101, the operation unit 102, the image reader control unit 201, the image signal control unit 202, the printer control unit 301, the stacker control unit 401, and the sheet processing apparatus control unit. 501 is collectively controlled.

  The sheet processing apparatus control unit 501 controls a sheet processing apparatus (not shown) connected to the stacker 100. In FIG. 2, reference numeral 203 denotes an external I / F that is an interface between the image forming apparatus 900 and an external computer 204. The print data from the computer 204 is expanded into a bitmap image, and an image signal control unit as image data To 202.

  The RAM 152 temporarily stores control data and is used as a work area for arithmetic processing associated with control. The document feeding control unit 101 controls driving of the document feeding device 950 based on an instruction from the CPU circuit unit 150. The image reader control unit 201 performs drive control on the scanner unit 955 and the image sensor 954 provided in the image reading device 951 and transfers an analog image signal output from the image sensor 954 to the image signal control unit 202. is there.

  The image signal control unit 202 converts each analog image signal from the image sensor 954 into a digital signal, performs each process, converts the digital signal into a video signal, and outputs the video signal to the printer control unit 301. The digital image signal input from the computer 204 via the external I / F 203 is subjected to various processes, and the digital image signal is converted into a video signal and output to the printer control unit 301. The processing operation by the image signal control unit 202 is controlled by the CPU circuit unit 150.

  The printer control unit 301 drives the exposure unit 908 via an exposure control unit (not shown) based on the input video signal. The operation unit 102 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. A key signal corresponding to the operation of each key is output to the CPU circuit unit 150, and corresponding information is displayed on the display unit based on the signal from the CPU circuit unit 150.

  Here, for example, the user can input sheet size information, that is, length information in the width direction of the sheet, from the operation unit 102 serving as an input unit. The CPU circuit unit 150 controls the stacking operation of the stacker 100 via the stacker control unit 401 based on the sheet size information (the length information in the sheet discharge direction) input from the operation unit 102. . When the image forming apparatus 900 is controlled by the external computer 204, the sheet size information is input from the external computer 204, not from the operation unit 102.

  The stacker control unit 401 is mounted on the stacker 100 and controls the driving of the first alignment member drive motor 320 and the second alignment member drive motor 330 by exchanging information with the CPU circuit unit 150. Further, the stacker control unit 401 performs drive control of the entire stacker such as the first auxiliary alignment member drive motor 322, the second auxiliary alignment member drive motor 332, and a gripper belt motor (not shown). This control content will be described later.

  Note that the stacker control unit 401 may be integrated into the CPU circuit unit 150 on the image forming apparatus main body 901 side so as to control the stacker 100 directly from the image forming apparatus main body 901.

  FIG. 3 is a diagram illustrating a configuration of the stacker 100 connected to the image forming apparatus main body 901. In FIG. 3, reference numeral 8 denotes a gripper belt. The gripper belt 8 is suspended from a drive pulley 11 and a driven pulley 12 and is rotationally driven by gear transmission from a gripper belt motor (not shown), and has the same sheet conveying speed. It rotates in the direction of arrow 13 at speed.

  Reference numerals 7a and 7b denote grippers for sandwiching a sheet conveyed from a sheet discharge roller 5 serving as a sheet discharge unit. The grippers 7a and 7b are attached to the gripper belt 8 and are integrated with the gripper belt 8 in the direction of arrow 13. Move at the same speed as the sheet conveyance speed. Then, by being sandwiched by the grippers 7a and 7b, the sheet is conveyed to a predetermined position along the sheet conveying direction above the stacking tray 6 which is a sheet stacking unit.

  That is, in the present embodiment, the transfer means for transferring the sheet discharged from the paper discharge roller 5 to a predetermined position on the stacking tray includes grippers 7a and 7b which are a plurality of holding means for holding (holding) the sheets, And a gripper belt 8.

  Reference numeral 14 denotes a front end stopper which is a contact portion that contacts the front end of the sheet and positions the sheet, and includes a slope 14a on which the sheet held by the grippers 7a and 7b abuts, and a sheet retracting means 16. Here, when the grippers 7a and 7b move in the direction of the leading end stopper 14 by the rotation of the gripper belt 8, the leading ends of the sheets held by the grippers 7a and 7b eventually come into contact with the inclined surface 14a. Then, the sheet is released from the grippers 7a and 7b by the front end contacting the inclined surface 14a in this way.

  Further, after being released from the grippers 7a and 7b, the sheet is discharged toward the sheet retracting means 16, and thereafter, the sheet retracting means 16 causes the leading edge of the sheet to abut against the abutting surface 14b of the leading end stopper 14. Then, the sheet tip is positioned.

  Next, the operation of the stacker 100 when sheets are stacked on the stacking tray 6 will be described with reference to FIG.

  When the sheet is discharged from the image forming apparatus main body 901, the sheet is carried into the entrance roller 1, and then the path is switched by the first switching member 2 in accordance with a selection instruction from the operation unit 102 or the computer 204, and is conveyed. Is done. Further, for example, when the user designates the sheet stacking position for the sample tray 9 on the upper surface of the stacker, the sheet is directed to the sample tray 9 by switching the second switching member 17 thereafter. When conveyance to a sheet processing apparatus (not shown) connected downstream is specified, the sheet passes through the conveyance path 3 by the upward rotation of the second switching member 17 and is discharged from the exit roller 4 to the sheet processing apparatus. To be transported.

  When the user designates the sheet stacking position on the stacking tray 6, the sheet is guided to the sheet discharge roller 5 by switching the first switching member 2. Thereafter, the sheet is gripped by one of the two grippers 7a and 7b and conveyed on the stacking tray while being sandwiched between the gripper 7a and the paper discharge roller 5.

  Next, by coming into contact with the inclined surface 14 a of the leading end stopper 14 at the position shown in FIG. 3, the gripper 7 a is released and discharged toward the sheet retracting means 16 provided integrally with the leading end stopper 14.

  Note that the distance between the sheet drawing means 16 and the paper discharge roller 5 is set to be shorter than the length of the discharged sheet. Therefore, after that, the sheet is guided by the sheet drawing means 16 to the contact surface 14b of the leading end stopper 14, whereby the leading end position is regulated, and the stacking tray 6 with the leading end position regulated in this way is regulated. Loaded on top. Thereafter, the next sheet discharged from the paper discharge roller 5 is conveyed and stacked on the stacking tray while the leading edge is held by the next gripper 7b.

  The upper surface of the sheet bundle placed on the stacking tray 6 is detected by a paper surface detection sensor (not shown). When the paper surface detection sensor detects that the upper surface position of the sheet bundle placed on the stacking tray 6 is higher than a predetermined position, the stacker control unit 401 controls the stacking tray 6 to be lowered. .

  4 is a side view of the vicinity of the stacking tray 6 of the stacker 100. In FIG. 4, reference numerals 20 and 30 denote first and second alignment members that align the side edge positions of the sheets. The first and second alignment members 20 and 30 are provided to face each other in the width direction, and can be independently moved in the width direction by the first alignment member drive motor 320 and the second alignment member drive motor 330 shown in FIG. It has become. Further, the first and second alignment members 20 and 30 include contact surfaces 22 and 32 which are side surfaces that contact the sheet, and auxiliary alignment members 21 and 31.

  Here, an auxiliary alignment member 21 (hereinafter referred to as a first auxiliary alignment member) provided on the first alignment member 20 is provided on the contact surface 22 so as to be movable in the vertical direction. When the first alignment member 20 is in a first reference position, which will be described later, the first auxiliary alignment member 21 presses a bundle of sheets by a first auxiliary alignment member drive motor 322 shown in FIGS. As the second alignment member 30 moves, it moves to a contact position where it abuts against the moving sheet.

  An auxiliary alignment member 31 (hereinafter referred to as a second auxiliary alignment member) provided on the second alignment member 30 is provided on the contact surface 32 so as to be movable in the vertical direction. When the second alignment member 30 is in a second reference position, which will be described later, the second auxiliary alignment member 31 holds the sheet bundle and presses the first alignment by the second auxiliary alignment member drive motor 332 shown in FIG. As the member 20 moves, it moves to a contact position where it abuts against the moving sheet.

  Here, in the present embodiment, the sheet discharge position on the stacking tray 6 in the width direction is relative to the auxiliary alignment members 21 and 31 when the first and second alignment members 20 and 30 are at the reference positions, respectively. Thus, the end of the discharge sheet in the width direction is set to have a predetermined interval. And the width direction position where the other edge part of a discharge sheet does not interfere with the 1st and 2nd aligning members 20 and 30, and also crawls into the lower part of the 1st and 2nd auxiliary aligning members 21 and 31 which moved upwards To be discharged.

  Further, when the stacking of the sheet bundle is completed, the first and second alignment members 20 and 30 are moved in the direction of the sheet bundle by the first and second alignment member driving motors 320 and 330 while being synchronized. Regulates the position in the width direction.

  Further, when stacking of one sheet bundle is finished, the stacker 100 shifts (shifts) the next sheet bundle on the sheet bundle in the width direction, that is, stacks the sheet bundle into the sheet bundle. Shift loading, in which loading positions are switched, can be performed. Next, shift stacking in the stacker 100 will be described with reference to the flowchart shown in FIG.

  First, the stacker control unit 401 determines whether or not to stack sheets based on an instruction from the CPU circuit unit 150 on the image forming apparatus main body 901 side or an instruction from the operation unit 102 or the like (S100). Here, when it is determined that the sheets are stacked on the stacking tray, that is, stacked on the stacking tray (Y in S100), the stacker control unit 401 next transfers the sheet width direction from the operation unit 102 or the computer 204. The sheet information such as the length of the sheet is input (S101). If it is determined that the sheets are not stacked (N in S100), the process proceeds to another process (S102).

  Next, it is determined whether or not sheets are shifted and stacked on the stacking tray (S103). When sheets are shifted and stacked (Y in S103), one alignment member, for example, the second alignment member 30 as shown in FIG. 4, the length in the width direction of the sheet from the operation unit 102 or the computer 204 is used. It is moved to the reference position (second reference position) according to the information (S110). At this time, the second auxiliary alignment member 31 of the second alignment member 30 is moved to the contact position. Further, the first auxiliary alignment member 21 of the first alignment member 20, which is the other alignment member, is moved upward by the first auxiliary alignment member drive motor 322 and retracted to a position where it does not contact the sheet (S111).

  Next, the first alignment member 20 is moved in a direction away from the second alignment member 30 by a distance obtained by adding the length in the width direction of the first auxiliary alignment member 21 and a predetermined margin. The sheet is moved to the sheet receiving position corresponding to the length (S112). Thereafter, the sheet P is discharged (S113), and each time the sheet P is discharged, the first alignment member 20 is moved by a predetermined amount in the direction of the second alignment member 30 indicated by the arrow, and the sheet P is moved to the second alignment member. The 30 sheets of the second auxiliary alignment members 31 are brought into contact with each other, and the discharged sheets are aligned (S114).

  As a result, the discharged sheet is aligned by the first and second alignment members 20 and 30 at a position shifted toward the second alignment member. The length in the width direction of the first and second auxiliary alignment members 21 and 31 is the amount of deviation between the sheet bundles. The order of movement of the first and second alignment members 20 and 30 and the first and second auxiliary alignment members 21 and 31 may not be as described above, and any of them may be moved simultaneously.

  After the sheets are aligned as described above, the first alignment member 20 moves in the direction opposite to the arrow and returns to the sheet receiving position. After such an alignment operation, it is determined whether or not the discharged sheet is the final sheet of the sheet bundle (S115). If the discharged sheet is not the final sheet of the sheet bundle (N in S115) ) And S112 to S114 are repeated.

  Thereafter, when the sheets are sequentially discharged onto the stacking tray and eventually the final sheet of the sheet bundle PA is discharged as shown in FIG. 7A (Y in S115), this discharge is next performed. It is determined whether or not the last sheet is the last sheet of the job (job) (S116). If the discharged sheet is the final sheet of the job (Y in S116), the sheet stacking operation is terminated.

  On the other hand, if the discharged sheet is not the final sheet of the job (N in S116), the sheet is then shifted onto the previously stacked sheet bundle PA at the position shifted to the first alignment member side and stacked. To do. For this reason, first, as shown in FIG. 7A, the first alignment member 20 is moved to the reference position (first reference position) (S117).

  Thereafter, the second alignment member 30 is moved in the direction of the first alignment member 20 moved to the reference position, and the aligned sheet bundle PA is brought into contact with the contact surface 22 of the first alignment member 20. Thereafter, as shown in FIG. 7B, the first auxiliary alignment member 21 is lowered and brought into contact with the upper surface of the side end portion of the sheet bundle PA already stacked on the stacking tray.

  Here, in the present embodiment, the first auxiliary alignment member 21 is movable in the vertical direction by the first auxiliary alignment member drive motor 322 that can be rotated forward and backward as described above. The first auxiliary alignment member 21 is lowered by a predetermined amount by the reverse rotation of the first auxiliary alignment member drive motor 322 and comes into contact with the upper surface of the side end portion of the sheet bundle PA.

  As described above, the stacking tray 6 is lowered so that the upper surface position of the sheet bundle placed on the stacking tray 6 is kept constant. For this reason, when the sheet stacking amount increases, the first auxiliary alignment member 21 that has been in contact with the upper surface of the already stacked sheet bundle PA is separated from the upper surface of the sheet bundle PA, and has a substantially constant positional relationship with the discharged sheets to be aligned. Touch.

  Next, after the first auxiliary alignment member 21 is brought into contact with the upper surface of the sheet bundle PA in this way, the second auxiliary alignment member 31 of the second alignment member 30 is moved upward by the second auxiliary alignment member drive motor 332. And retracted to a position where it does not contact the sheet (S118). Further, after the second auxiliary alignment member 31 is moved to the retracted position in this way, the second alignment member 30 is moved by the distance obtained by adding the length in the width direction of the second auxiliary alignment member 31 and a predetermined margin. The first alignment member 20 is moved away from the alignment member 20 to the sheet receiving position (S119).

  Thereafter, the sheet P is discharged (S120), and each time the sheet P is discharged, the second alignment member 30 is moved by a predetermined amount in the direction of the first alignment member 20 indicated by an arrow as shown in FIG. . As a result, the sheet P is brought into contact with the first auxiliary alignment member 21 of the first alignment member 20, and the discharged sheet is aligned (S121). As a result, the discharged sheet P is aligned by the first and second alignment members 20 and 30 at a position shifted toward the second alignment member as shown in FIG.

  After such an alignment operation, it is determined whether or not the discharged sheet P is the final sheet of the sheet bundle (S122), and if the discharged sheet P is not the final sheet of the sheet bundle PB (S122). N), the operations of S119 to S121 are repeated.

  Thereafter, when the sheets are sequentially discharged onto the stacking tray and the final sheet of the sheet bundle is eventually discharged (Y in S122), it is next determined whether or not the discharged sheet is the final sheet of the job. Judgment is made (S123). If the discharged sheet is not the final sheet of the job (N in S123), the operations in S110 to S122 are repeated. If the discharged sheet is the final sheet of the job (Y in S123), the sheet stacking operation is terminated.

  If the sheet surface detection sensor detects that the upper surface position of the sheet bundle placed on the stacking tray 6 has become higher than a predetermined position before the final sheet of the job is discharged, the stacking tray 6 Is controlled to descend.

  If shift stacking is not performed (N in S103), both auxiliary alignment members 21 and 31 are retracted upward (S130), and then both alignment members 20 and 30 are moved to the receiving positions (S131).

  Thereafter, the sheet P is discharged (S132), and each time the sheet P is discharged, the alignment members 20, 30 are moved by a predetermined amount in a direction approaching each other, and the discharged sheets are aligned (S133). After such an alignment operation, it is determined whether or not the discharged sheet is the final sheet of the job (S134). If the discharged sheet is not the final sheet of the job (N in S134), the operations in S131 to S133 are repeated. If the discharged sheet is the final sheet of the job (Y in S134), the sheet stacking operation is terminated.

  Thus, in the present embodiment, when the first alignment member 20 is at the reference position, the first auxiliary alignment member 21 is lowered to press the sheet bundle, and the second alignment member 30 is at the reference position. The second auxiliary alignment member 31 is lowered to press the sheet.

  Thus, when switching the stacking position of the sheet bundle, by bringing one of the auxiliary alignment members 21 and 31 provided on the first and second alignment members 20 and 30 into contact with the upper surface of the sheet bundle, The time required for switching the stack position of the sheet bundle can be shortened. Further, by shortening the time required for switching the stack position of the sheet bundle in this way, it is possible to reduce the time that cannot be stacked between the bundles, and it is possible to cope with the speeding up of the image forming operation of the image forming apparatus. It becomes.

  In the present embodiment, as shown in FIG. 7 described above, when the sheet bundle is alternately shifted in the width direction and stacked, the upper surface of the sheet bundle is pressed by the auxiliary alignment members 21 and 31. Therefore, the alignment of the already loaded bundle is not disturbed. In addition, when changing the stacking position between bundles, the switching is completed simply by moving the auxiliary alignment member up and down, so that high productivity is not impaired.

  Furthermore, in the present embodiment, the first and second alignment members 20, 30 are controlled independently. For this reason, the movement amount of the first and second aligning members 20 and 30 is changed in consideration of the skew amount of the discharged sheet, and the sheet is discharged by aligning with the aligning means on the side not on the already loaded bundle. Sometimes the sheet comes into contact with the aligning means, and troubles such as poor loading can be reduced.

  In the present embodiment, as shown in FIG. 8, the first auxiliary alignment member 21 is biased downward by a spring 40. This configuration is the same for the second auxiliary alignment member 31.

  Then, the first auxiliary alignment member 21 comes into pressure contact with the sheet bundle PA with a predetermined pressure by contacting the upper surface of the side end portion of the sheet bundle PA while contracting the spring 40 in this way. Accordingly, when other sheets are stacked on the sheet bundle PA, the sheets can be prevented from entering the bottom surface of the first auxiliary alignment member 21.

  Further, for example, as shown in FIG. 8B, the discharged sheet bundle PA has a large curl, and a gap may be generated between the stacking tray 6 and the already stacked bundle PA. In this case, by controlling the stop position of the first auxiliary alignment member 21, curling of the already loaded bundle PA can be suppressed as shown in FIG. As a result, it is possible to prevent a trouble that the sheets are trapped and misaligned when the sheets are stacked.

1 is a diagram illustrating a configuration of an image forming apparatus including a sheet stacking apparatus according to an embodiment of the present invention. FIG. 3 is a control block diagram of a control unit provided in the image forming apparatus. FIG. 3 is a diagram illustrating a configuration of a stacker connected to an image forming apparatus main body of the image forming apparatus. The side view of the stacker vicinity of the stacker. The perspective view which shows the structure of the 1st alignment member provided in the said stacker. The flowchart explaining the shift loading in the said stacker. The figure explaining the shift loading in the said stacker. The figure which shows operation | movement when pressing the sheet | seat bundle of the 1st auxiliary | assistant alignment member provided in the said 1st alignment member. The figure which shows the structure of the conventional large capacity | capacitance stacker apparatus. FIG. 10 is a first diagram illustrating a shift stacking method of a conventional stacker device. FIG. 9 is a second diagram illustrating a conventional stacking method of the stacker device.

Explanation of symbols

20 first alignment member 21 first auxiliary alignment member 22 contact surface 30 second alignment member 31 second auxiliary alignment member 32 contact surface 100 stacker 102 operation unit 320 first alignment member drive motor 322 first auxiliary alignment member drive motor 330 Second alignment member driving motor 332 Second auxiliary alignment member driving motor 401 Stacker controller 900 Image forming apparatus 901 Image forming apparatus main body 902 Image forming section P Sheet

Claims (5)

A sheet stacking unit, and a first alignment member and a second alignment member, which are provided so as to be movable in a width direction orthogonal to the sheet discharge direction, and align a position in the width direction of the sheet discharged to the sheet stacking unit, When stacking other sheet bundles on the aligned sheet bundle while shifting in the width direction, the second alignment member is moved toward the first alignment member at the first reference position. In the sheet stacking apparatus for moving the first alignment member toward the second alignment member moved to the second reference position and aligning and stacking other sheet bundles after aligning the bundle of sheets,
When the first alignment member is in the first reference position, the first alignment member moves with the movement of the second alignment member. A first auxiliary alignment member that moves to a contact position that abuts against the sheet;
When the second alignment member is in the second reference position, the side surface of the second alignment member that is in contact with the sheet is moved so as to move along with the movement of the first alignment member. A sheet stacking apparatus comprising: a second auxiliary alignment member that moves to a contact position that abuts against a sheet.   When the first alignment member moves, the first auxiliary alignment member moves to a retracted position where it does not come into contact with the moving sheet as the first alignment member moves, and the second auxiliary alignment member 2. The sheet stacking apparatus according to claim 1, wherein when the second alignment member moves, the second alignment member moves to a retreat position where the second alignment member does not contact the moving sheet.   When aligning the sheet by moving both the first alignment member and the second alignment member, both the first auxiliary alignment member and the second auxiliary alignment member are moved to the retracted position. The sheet stacking apparatus according to claim 2.   4. The sheet stacking apparatus according to claim 1, wherein the first reference position and the second reference position move according to a length in a width direction of the sheet. 5.   An image forming unit that forms an image on a sheet, and a sheet stacking device according to any one of claims 1 to 4, further comprising a sheet stacking unit that stacks sheets discharged after image formation. An image forming apparatus.

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