JP2010222080A - Sheet stacking device, method of controlling the same and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet stacking device capable of preventing stacking preparation processing from being performed in an opened state of a cover, even when take-out processing and the stacking preparation processing are overlapped. <P>SOLUTION: When a take-out switch 841 is pressed and a take-out operation is started in a tray take-out priority control, starting of a stack part stacking job is suspended. When a paper discharge destination of the fed stack part stacking job does not coincide with a stack tray 821 in take-out processing, even when the take-out switch 841 is pressed and the take-out processing is started in a printing priority control, the following operation is performed, that is, the take-out processing is suspended if the cover 840 is before the opening, and the stacking preparation processing is preferentially processed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet stacking apparatus that stacks sheets, a control method thereof, and an image forming system.

  2. Description of the Related Art In recent years, image forming apparatuses that form an image on a sheet can discharge a large amount of sheets from the main body of the image forming apparatus by increasing the image forming speed by the advancement and improvement of image forming technology. Can now.

  Therefore, a sheet stacking apparatus that is connected to the apparatus main body of the image forming apparatus and stacks sheets discharged from the apparatus main body is required to be able to stack sheets with a large capacity. A sheet stacking apparatus (hereinafter referred to as a “stacker”) that meets this requirement is described in Japanese Patent Application Laid-Open No. 2004-133830.

  In this stacker (see FIG. 3), a plurality of stacking trays are arranged in the sheet conveying direction so that they can be selectively used according to the length of the sheet so that the space in the apparatus can be used effectively. In addition, if this stacker is a sheet size that can be loaded on one stacking tray, a stacking operation on the other stacking tray can be continued even during the take-out operation, so that a large number of sheets can be stored without stopping the apparatus. It can be loaded continuously.

  From the viewpoint of preventing malfunctions and ensuring safety when a user touches an operating unit as a control that has been performed on the entire device, the operation of the unit is restricted when the cover for covering the unit is open. It is generally done.

  Even in a stacker that continues the stacking operation between a plurality of stacking trays disclosed in Patent Document 1, when a stacking tray or a unit necessary for alignment processing is moved to the stacking position, the cover is open. The following is required. That is, if the user accidentally touches the unit, the unit position related to the loadability is prevented from deteriorating from the normal position, and the user is prevented from touching the moving unit. Therefore, it is necessary to ensure safety.

  For this reason, in a state where the cover for covering the stacking tray is opened by the take-out operation, it is necessary to restrict the moving process of the stacking tray and the unit related to the alignment process.

JP 2008-087965 A

  However, the conventional sheet stacking apparatus has the following problems. In a stacker that continues the stacking operation between a plurality of stacking trays, it has been considered that the extraction process and the stacking preparation process may overlap depending on the execution timing of the user's extraction operation. That is, when an instruction to start stacking on the stack tray that is not the target of removal is given until the stack tray reaches the take-out position by the take-out operation and the cover is opened, the above two processes may overlap. .

  In this way, when the take-out process and the stack preparation process overlap, even when the cover by the take-out operation is open, the load preparation process is performed by starting the loading on the stack tray that is not the take-out object. Then, a state occurs in which the user can touch the unit that moves in the loading preparation process.

  Therefore, the present invention provides a sheet stacking apparatus, a control method thereof, and an image forming system capable of preventing the stacking preparation process from being performed with the cover member opened even when the take-out process and the stacking preparation process overlap. With the goal.

  In order to achieve the above object, a sheet stacking apparatus according to the present invention includes a sheet transporting unit that transports a sheet discharged from a sheet supply device, and a plurality of sheet stacking units that stack the sheets transported by the sheet transporting unit. , A moving unit that individually moves the plurality of sheet stacking units, an openable / closable cover member for covering the plurality of sheet stacking units, and a sheet take-out instruction to the plurality of sheet stacking units individually. An instructing unit that moves the instructed sheet stacking unit to a predetermined position, and when the sheet stacking unit moves to the predetermined position, opens the cover member. A sheet stacking apparatus that performs a take-out process that permits an operation, wherein the sheet load is instructed by the take-out instruction unit. If you start the retrieval processing means, characterized by comprising a control means for inhibiting the loading start of sheets to said sheet stacking means.

  The sheet stacking apparatus according to the present invention includes a sheet transporting unit that transports a sheet discharged from a sheet supply device, a plurality of sheet stacking units that stack the sheet transported from the sheet transporting unit, and the plurality of sheet stacking units. A moving unit that individually moves the sheet; a sheet stacking recognition unit that recognizes a request to start stacking sheets on the sheet stacking unit; an openable and closable cover member that covers the plurality of sheet stacking units; and the plurality of sheets A take-out instructing unit that individually issues a take-out instruction to the stacking unit, and when the take-out instruction is instructed by the take-out instructing unit, the instructed sheet stacking unit is moved to a predetermined position; Is a sheet stacking apparatus that performs a take-out process that permits an opening operation of the cover member when the cover member moves to the predetermined position. When the sheet stacking recognition unit recognizes a request to start stacking sheets on the sheet stacking unit that has not been instructed to take out, the picking process is interrupted, and the sheet stacking unit requested to start stacking the sheet is sent to the sheet stacking unit. And a control means for restarting the take-out process after performing the preparatory process prior to loading.

  The sheet stacking apparatus according to the present invention includes a sheet transporting unit that transports a sheet discharged from a sheet supply device, a plurality of sheet stacking units that stack the sheet transported from the sheet transporting unit, and the plurality of sheet stacking units. A moving unit that individually moves the sheet; a sheet stacking recognition unit that recognizes a request to start stacking sheets on the sheet stacking unit; an openable and closable cover member that covers the plurality of sheet stacking units; and the plurality of sheets When an instruction is given to the stacking means for taking out the sheets individually, and when the takeout instruction is issued by the takeout instruction means, the instructed sheet stacking means is moved to a predetermined position, and the sheet stacking means Control means for performing a take-out process that permits an opening operation of the cover member when moved to a predetermined position, and the control means When the take-out operation of the sheet stacking unit instructed by the take-out instruction unit is started, a first priority control for prohibiting the start of stacking of sheets on the sheet stacking unit and the take-out instruction by the sheet stacking recognition unit When a request for starting the stacking of sheets on the sheet stacking unit that has not been recognized is recognized, the take-out process is interrupted, and a preparation process before performing the stacking on the sheet stacking unit requested to start stacking the sheets And then selectively executing the second priority control for restarting the take-out process, and further manually selecting either the first priority control or the second priority control. It is characterized by comprising selection means for selecting.

  The method for controlling a sheet stacking apparatus according to the present invention includes: a sheet transport unit that transports a sheet discharged from a sheet supply device; a plurality of sheet stack units that stack a sheet transported by the sheet transport unit; and the plurality of sheets. A moving means for individually moving the stacking means; an openable / closable cover member for covering the plurality of sheet stacking means; and a takeout instruction means for individually giving a sheet takeout instruction to the plurality of sheet stacking means. In the control method of the provided sheet stacking apparatus, when the take-out instruction is instructed by the take-out instructing unit, the instructed sheet stacking unit is moved to a predetermined position, and when the sheet stacking unit is moved to the predetermined position, the cover A step of performing a take-out process permitting the opening operation of the member, and the sheet instructed by the take-out instructing means. If you start the retrieval processing of bets stacking means, characterized by a step of prohibiting the loading start of sheets to said sheet stacking means.

  The method for controlling a sheet stacking apparatus according to the present invention includes: a sheet transport unit that transports a sheet discharged from a sheet supply device; a plurality of sheet stack units that stack a sheet transported from the sheet transport unit; and the plurality of sheets. A moving means for individually moving the stacking means; a sheet stacking recognition means for recognizing a request to start stacking sheets on the sheet stacking means; an openable / closable cover member for covering the plurality of sheet stacking means; In a control method of a sheet stacking apparatus including a plurality of sheet stacking units, a sheet stacking instruction unit that individually issues a sheet stacking instruction. When the sheet stacking unit moves to the predetermined position, the opening operation of the cover member is permitted. A step of performing an unloading process, and when the sheet stacking recognition unit recognizes a request to start stacking of sheets on the sheet stacking unit that has not been instructed to unload, the unloading process is interrupted and the stacking of the sheet is started And a step of restarting the take-out process after performing a preparatory process before stacking on the sheet stacking means requested.

  The method for controlling a sheet stacking apparatus according to the present invention includes: a sheet transport unit that transports a sheet discharged from a sheet supply device; a plurality of sheet stack units that stack a sheet transported from the sheet transport unit; and the plurality of sheets. A moving means for individually moving the stacking means; a sheet stacking recognition means for recognizing a request to start stacking sheets on the sheet stacking means; an openable / closable cover member for covering the plurality of sheet stacking means; In a control method of a sheet stacking apparatus including a plurality of sheet stacking units, a sheet stacking instruction unit that individually issues a sheet stacking instruction. When the sheet stacking unit moves to the predetermined position, the opening operation of the cover member is permitted. A take-out process step for performing a take-out process; and a first priority control step for prohibiting the start of stacking of sheets on the sheet stacking means when the take-out operation of the sheet stacking means instructed by the take-out instructing means is started. In the take-out processing step, when the sheet stacking recognizing unit recognizes a request to start stacking sheets on the sheet stacking unit that has not been instructed to take out, the take-out processing is interrupted, and the stacking of sheets is started. A second priority control step of restarting the take-out process after performing the requested preparatory process before stacking on the sheet stacking means, the first priority control step according to the selection by the operator, And a selection step of selecting any one of the second priority control steps.

  An image forming system according to the present invention includes an image forming apparatus that forms an image on a sheet, a sheet conveying unit that conveys a sheet discharged from the image forming apparatus, and a plurality of sheets that stack the sheets conveyed by the sheet conveying unit. A sheet stacking unit; a moving unit that individually moves the plurality of sheet stacking units; an openable / closable cover member for covering the plurality of sheet stacking units; and a sheet take-out instruction to the plurality of sheet stacking units. And when the removal instruction is instructed to move, the instructed sheet stacking unit is moved to a predetermined position, and when the sheet stacking unit is moved to a predetermined position, the cover An image forming system comprising: a sheet stacking device that performs a take-out process that permits a member opening operation, If you start the retrieval processing of the sheet stacking means which is instructed by the instruction means, characterized by comprising a control means for inhibiting the loading start of sheets to said sheet stacking means.

  An image forming system according to the present invention includes an image forming apparatus that forms an image on a sheet, a sheet conveying unit that conveys a sheet discharged from the image forming apparatus, and a plurality of sheets that stack the sheets conveyed from the sheet conveying unit. A sheet stacking unit; a moving unit that individually moves the plurality of sheet stacking units; a sheet stacking recognition unit that recognizes a request to start stacking sheets on the sheet stacking unit; and a cover for covering the plurality of sheet stacking units. A cover member that can be opened and closed, and a take-out instruction unit that individually issues a take-out instruction to the plurality of sheet stacking units. When the sheet stacking means is moved to the predetermined position, the opening operation of the cover member is permitted. An image forming system including a sheet stacking device that performs a sheet stacking process, wherein when the sheet stacking recognition unit recognizes a request to start stacking sheets on the sheet stacking unit that is not instructed to stack Control means for restarting the take-out process after performing a preparatory process prior to stacking on the sheet stacking means requested to start stacking the sheets is provided.

  An image forming system according to the present invention includes an image forming apparatus that forms an image on a sheet, a sheet conveying unit that conveys a sheet discharged from the image forming apparatus, and a plurality of sheets that stack the sheets conveyed from the sheet conveying unit. A sheet stacking unit; a moving unit that individually moves the plurality of sheet stacking units; a sheet stacking recognition unit that recognizes a request to start stacking sheets on the sheet stacking unit; and a cover for covering the plurality of sheet stacking units. An openable / closable cover member, a takeout instructing unit that individually issues a takeout instruction to the plurality of sheet stacking units, and when the takeout is instructed by the takeout instruction unit, the instructed sheet stacking unit is When the sheet stacking unit is moved to a predetermined position and the sheet stacking unit is moved to the predetermined position, the cover member is allowed to be opened. An image forming system comprising: a control unit configured to perform stacking of sheets on the sheet stacking unit when the control unit starts the sheet stacking unit extraction operation instructed by the extraction instruction unit. When the first priority control prohibiting the start and the sheet stacking recognition unit recognizes a request to start stacking of the sheets on the sheet stacking unit for which an extraction instruction has not been issued, the extraction process is interrupted, and the sheet And a second priority control for restarting the take-out process after performing a preparatory process before stacking on the sheet stacking unit requested to start stacking, and further, Selection means for manually selecting one of the first priority control and the second priority control is provided.

  The sheet stacking apparatus according to claim 1 of the present invention prohibits the start of stacking of sheets on the sheet stacking unit when the instructed process of taking out the sheet stacking unit is started. As described above, when the take-out process of the sheet stacking unit is started, the take-out process can be preferentially processed by prohibiting the start of the stacking of sheets. Therefore, even when the take-out process and the preparatory process before the stacking overlap, it is possible to prevent the preparatory process before the stacking from being performed with the cover member opened.

  When the sheet stacking apparatus according to the second aspect recognizes a request for starting the stacking of sheets on a sheet stacking unit for which an instruction for taking out has not been given, the takeout process is interrupted. Then, the sheet stacking apparatus performs the sheet stacking process on the sheet stacking unit by performing the preparatory process before stacking on the sheet stacking unit requested to start the sheet stacking and then restarting the takeout process. Can continue. Therefore, it is possible to prevent the preparatory process before the stacking from being performed in a state where the cover member is open.

  In this way, the take-out process can be suspended and the preparatory process before loading can be prioritized. As a result, when connected to the image forming apparatus, the printing process can be started earlier by the user's take-out operation time than the control in which the take-out process is prioritized.

  In addition, when the preparatory process before stacking is completed, it is possible to continuously stack a large number of sheets by allowing sheets already stacked to be taken out while stacking sheets. Accordingly, the sheet stacking space can be used effectively.

  According to the sheet stacking apparatus according to claims 3, 4 and 5, since either one of the control for prioritizing the take-out process or the control for prioritizing the preparatory process before stacking is selected, the control according to the needs of the user is selected. It can be performed. That is, it is possible to perform control for giving priority to the take-out process to a user who wants to stop the sheet stacking and perform the take-out operation quickly. In addition, even when waiting for the take-out operation, it is possible to perform control for giving priority to the preparation process before stacking for a user who wants to continue stacking operation and continue sheet stacking. Thereby, user operability can be improved.

  According to the sheet stacking apparatus of the sixth aspect, since the aligning unit is prepared, the sheets stacked on the sheet stacking unit can be aligned, and the productivity and quality of the sheet bundle are improved.

  According to the sheet stacking apparatus of the seventh aspect, the height of the upper surface of the sheet stacking unit or the upper surface of the stacked sheet is detected in advance, and the sheet stacking unit that is a sheet stacking destination is moved to the sheet stacking position. Thus, it is possible to promptly shift to the start of sheet stacking.

  According to the sheet stacking apparatus of the eighth aspect, when the length of the sheet in the sheet transport direction is larger than the length that can be stacked on one sheet stacking unit, the stacked sheets are stacked across the plurality of sheet stacking units. As a result, the types of sheets to be stacked can be increased.

1 is a diagram illustrating a configuration of an image forming system including a sheet stacking apparatus according to an embodiment. 2 is a block diagram illustrating a configuration of a controller 60 that controls the entire image forming system. FIG. It is a figure which shows the internal structure of the stacker. 3 is a front view illustrating an appearance of an operation display device 400. FIG. It is a figure which shows operation | movement of the stacker 800. It is a figure which shows operation | movement of the stacker 800. It is a figure which shows operation | movement of the stacker 800. It is a figure which shows operation | movement of the stacker 800. It is a figure which shows operation | movement of the stacker 800. It is a figure which shows the operation | movement in the stack part 810. FIG. It is a figure which shows the operation | movement in the stack part 810. FIG. It is a figure which shows the operation | movement in the stack part 810. FIG. It is a figure which shows the operation | movement in the stack part 810. FIG. It is a figure which shows the operation | movement in the stack part 810. FIG. It is a figure which shows the operation | movement in the stack part 810. FIG. It is a figure which shows the operation | movement in the stack part 810. FIG. It is a figure which shows the operation | movement in the stack part 810. FIG. FIG. 10 is a diagram illustrating an operation in the stack unit 810 when sheets are stacked in the first stacking mode. FIG. 10 is a diagram illustrating an operation in the stack unit 810 when sheets are stacked in the second stacking mode. It is a figure which shows the external appearance of the stacker. It is a figure which shows the internal operation | movement of the stacker 800. FIG. It is a figure which shows the internal operation | movement of the stacker 800. FIG. It is a figure which shows the internal operation | movement of the stacker 800. FIG. It is a figure which shows the internal operation | movement of the stacker 800. FIG. It is a figure which shows the internal operation | movement of the stacker 800. FIG. It is a figure which shows the internal operation | movement of the stacker 800. FIG. It is a figure which shows the internal operation | movement of the stacker 800 when extraction operation of the stack tray 821b is performed during stacking operation | movement to the stack tray 821a. 6 is a diagram showing a tray removal mode setting screen displayed on a liquid crystal display unit 420. FIG. It is a flowchart which shows a tray taking-out priority control procedure. 6 is a flowchart illustrating a print priority control procedure. FIG. 20 is a flowchart illustrating a print priority control procedure continued from FIG. 19. FIG. 10 is a flowchart illustrating a selection processing procedure for selecting print priority control or tray ejection priority control.

  Embodiments of a sheet stacking apparatus, a control method thereof, and an image forming system of the present invention will be described with reference to the drawings. The sheet stacking apparatus of the present embodiment is connected to the image forming apparatus and constitutes an image forming system together with the image forming apparatus.

(overall structure)
FIG. 1 is a diagram illustrating a configuration of an image forming system including a sheet stacking apparatus according to an embodiment. The image forming system includes an image forming apparatus 10 and a sheet stacking apparatus (stacker) 800. The image forming apparatus 10 includes an image reader 200 and a printer 300 that read a document image.

  A document feeder 100 is mounted on the image reader 200. The document feeder 100 feeds documents set upward on the document tray one sheet at a time in order from the first page, flows on the platen glass 102 from the left through a curved path, and passes through the reading position. The paper is conveyed to the right, and then discharged toward the external paper discharge tray 112.

  When the original passes through the sink reading position on the platen glass 102 from the left to the right, the original image is read by the scanner unit 104 held at a position corresponding to the sink reading position. This reading method is generally referred to as document scanning. Specifically, when the original passes through the reading position, the original reading surface is irradiated with the light from the lamp 103 of the scanner unit 104, and the reflected light from the original passes through the mirrors 105, 106, and 107 to the lens. To 108. The light that has passed through the lens 108 forms an image on the imaging surface of the image sensor 109.

  In this way, the document is scanned so as to pass through the flow reading position from left to right, so that the direction perpendicular to the document transport direction is the main scanning direction, and the document scanning direction is the sub scanning direction. Is done.

  That is, when the original passes through the flow reading position, the entire original image is read by conveying the original in the sub-scanning direction while reading the original image by the image sensor 109 line by line in the main scanning direction. The optically read image is converted into image data by the image sensor 109 and output. Image data output from the image sensor 109 is subjected to predetermined processing in an image signal control unit 202 (see FIG. 2) described later, and then input as a video signal to the exposure unit 110 of the printer 300.

  It is also possible to read the document by transporting the document onto the platen glass 102 by the document feeder 100 and stopping it at a predetermined position, and scanning the scanner unit 104 from left to right in this state. This reading method is a so-called fixed document reading method.

  When reading a document without using the document feeder 100, a user (operator) first lifts the document feeder 100 and places the document on the platen glass 102. Then, by scanning the scanner unit 104 from left to right, the image reader 200 reads a document. That is, when reading a document without using the document feeder 100, a fixed document reading is performed.

  The exposure unit 110 in the printer 300 modulates and outputs a laser beam based on the input video signal. This laser beam is irradiated onto the photosensitive drum 111 while being scanned by the polygon mirror 110a. An electrostatic latent image corresponding to the scanned laser beam is formed on the photosensitive drum 111. The exposure unit 110 outputs a laser beam so that a correct image (an image that is not a mirror image) is formed in the case of fixed document reading. The electrostatic latent image on the photosensitive drum 111 is visualized as a developer image by the developer supplied from the developing device 113.

  In addition, paper is fed from each of the cassettes 114 and 115, the manual paper feeding unit 125, or the double-sided conveyance path 124 at a timing synchronized with the start of laser beam irradiation. This sheet is conveyed between the photosensitive drum 111 and the transfer unit 116. The developer image formed on the photosensitive drum 111 is transferred onto a sheet fed by the transfer unit 116.

  The sheet on which the developer image is transferred is conveyed to the fixing unit 117. The fixing unit 117 fixes the developer image on the paper by heat-pressing the paper. The sheet that has passed through the fixing unit 117 is discharged from the printer 300 to the outside (stacker 800) through the flapper 121 and the discharge roller 118.

  Here, when the sheet is discharged with its image forming surface facing down (face down), the printer 300 guides the sheet that has passed through the fixing unit 117 into the reverse path 122 by the switching operation of the flapper 121. Then, after the trailing edge of the paper passes through the flapper 121, the printer 300 switches back the paper and discharges the paper from the printer 300 toward the stacker 800 by the discharge roller 118.

  This paper discharge form is called reverse paper discharge. This reverse paper discharge is performed when forming an image sequentially from the first page, such as when forming an image read using the document feeder 100 or when forming an image output from a computer. The paper order after the paper discharge is the correct page order.

  In addition, when a hard sheet such as an OHP sheet is fed from the manual sheet feeding unit 125 and an image is formed on the sheet, the printer 300 does not lead the sheet to the reverse path 122 and the image forming surface faces upward. The paper is discharged by the discharge roller 118 in a state (face up).

  Further, when double-sided recording for forming an image on both sides of a sheet is set, the following control is performed. That is, after the paper is guided to the reverse path 122 by the switching operation of the flapper 121, it is transported to the double-sided transport path 124, and the paper guided to the double-sided transport path 124 is transferred between the photosensitive drum 111 and the transfer unit 116 at the timing described above. The sheet is fed again.

  The paper discharged from the printer 300 is sent to the stacker 800. The stacker 800 performs processing such as non-sort loading and shift sorting loading.

(System block diagram)
Next, the configuration of the controller that controls the entire image forming system will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the controller 60 that controls the entire image forming system. In the present embodiment, the controller 60 is placed in the image forming apparatus 10. The controller 60 may be placed outside the image forming apparatus 10 or in the stacker 800.

  The controller 60 has a CPU circuit unit 150. The CPU circuit unit 150 includes a CPU 151, a ROM 152, and a RAM 153, and the CPU 151 executes a control program stored in the ROM 152, thereby comprehensively controlling each unit described later. The RAM 153 temporarily stores control data and is used as a work area for arithmetic processing associated with control.

  The document feeder control unit 101 performs drive control of the document feeder 100 based on an instruction from the CPU circuit unit 150.

  The image reader control unit 201 performs drive control of the scanner unit 104, the image sensor 109, and the like, and transfers an analog image signal output from the image sensor 109 to the image signal control unit 202.

  The image signal control unit 202 converts each analog image signal from the image sensor 109 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 image signal control unit 202 performs various processes on the digital image signal input from the computer 210 via the external I / F 209, converts the digital image signal into a video signal, and outputs the video signal to the printer control unit 301. The operation of the image signal control unit 202 is controlled by the CPU circuit unit 150. The printer control unit 301 drives the exposure unit 110 based on the input video signal.

  The operation display device control unit 401 exchanges information between the operation display device 400 and the CPU circuit unit 150. As will be described later, the operation display device 400 includes a plurality of keys for setting various functions relating to image formation, a liquid crystal display unit for displaying information indicating a setting state, and the like. The operation display device 400 outputs a key signal corresponding to the operation of each key to the CPU circuit unit 150 and displays corresponding information on the liquid crystal display unit based on the signal from the CPU circuit unit 150.

  The stacker control unit 801 is mounted on the stacker 800 and performs drive control of the entire stacker by exchanging information with the CPU circuit unit 150.

(Stacker configuration)
Next, the configuration of the stacker 800 will be described with reference to FIG. FIG. 3 is a diagram showing an internal configuration of the stacker 800. The stack trays 821a and 821b are stack trays on which a large number of sheets discharged from the image forming apparatus 10 and sequentially taken into the apparatus are stacked, and are individually driven up and down by a motor (not shown). Note that the stack trays 821a and 821b are collectively referred to as a stack tray 821 when it is not necessary to distinguish between them.

  The width direction sheet restricting members 822a and 822b and the conveyance direction sheet restricting member (front end sheet restricting unit) 823 are driven by motors (not shown), respectively, to improve the stackability of sheets on the stack trays 821a and 821b. Here, the width direction is a direction orthogonal to the sheet conveyance direction. Note that the width direction sheet regulating members 822a and 822b are collectively referred to as a width direction sheet regulating member 822 when it is not necessary to distinguish between them.

  The sheet discharged from the image forming apparatus 10 is drawn into the stacker 800 through a conveyance path 811 at the sheet entrance. A conveyance path 812 is a conveyance path for conveying sheets to the stack tray 821 of the stacker 800.

  Further, in the shift sort mode in which the sheet is offset to the stack tray 821 and discharged in the middle of the conveyance path 812, the lateral registration correction is performed in which the sheet is conveyed while being shifted to a predetermined position in the width direction. A device 850 is provided. The width direction and the lateral direction are directions orthogonal to the sheet conveying direction. This lateral registration correction device is hereinafter referred to as a horizontal registration correction device.

  The lateral registration correction device 850 operates on all sheets discharged to the stack tray 821 in the shift sort mode, corrects lateral registration (hereinafter referred to as lateral registration) of the sheets, and widens the sheets. Transport while shifting to a predetermined position in the direction.

  The sheet on which the lateral registration is corrected by the lateral registration correcting device 850 is guided to the stack unit 810 through the conveyance path 813.

  The full load position detection sensors 817a and 817b detect the full load of the stack trays 821a and 821b, and are used when the stack trays 821a and 821b are lowered to the sheet take-out position. Note that the full load position detection sensors 817a and 817b are collectively referred to as full load position detection sensors 817 when it is not necessary to distinguish them.

  The position of the stack tray 821 detected by the full load position detection sensor 817 is the full load position for stacking sheets. When the stacker control unit 801 detects that the stack tray 821 has been lowered to the full load position by the full load position detection sensor 817, the stacker control unit 801 notifies the CPU circuit unit 150. The CPU circuit unit 150 controls each block (unit) so as to interrupt the conveyance of the sheet to the stacker 800. The full load position detection sensor 817a corresponds to full load detection of the stack tray 821a. The full load position detection sensor 817b corresponds to full load detection of the stack tray 821b.

  The lower limit position (removal position) of the stack tray 821 is a position further lowered by a predetermined amount than the position (full load detection position) where the full load position detection sensor 817 detects the stack tray 821.

  The sheet presence / absence detection sensors 818a and 818b are used to determine whether or not sheets are stacked on the stack trays 821a and 821b, respectively. The sheet presence / absence detection sensor 818a corresponds to the sheet detection of the stack tray 821a. The sheet presence / absence detection sensor 818b corresponds to the sheet detection of the stack tray 821b.

  When a sheet is discharged from the image forming apparatus 10, information on the size of the discharged sheet and the discharge destination is sent from the CPU circuit unit 150 to the stacker control unit 801. The stacker control unit 801 moves the width direction sheet regulating member 822 and the leading sheet regulating unit 823 according to the sheet size information according to the sheet size, and moves the stack trays 821a and 821b according to the discharge destination information. As a result, it becomes possible to sequentially stack the sheets in the state of being aligned with the stack tray 821.

  The leading sheet regulation unit 823 includes a paper surface detection sensor 816, a knurled belt 824, and a stopper 825. The leading edge sheet regulating unit 823 stands by at the home position on the left side of the stack unit 810 when the stacking operation is not performed. Upon receiving an instruction to start stacking on the stack unit 810, the leading sheet regulating unit 823 is driven by a motor (not shown) according to the length of sheets stacked on the stack tray 821 and the stacking mode, and moves in the transport direction. To do.

  The paper surface detection sensor 816 is a sensor that is provided in the leading edge sheet regulation unit 823 and detects the upper surface of a stacker sheet bundle stacked on the stack tray 821. The paper surface detection sensor 816 is used to keep the stack tray 821 at the sheet receiving position by a motor (not shown) when sheets are sequentially stacked on the stack tray 821.

  The knurled belt 824 rotates clockwise by a driving device (not shown), draws the sheet between the knurled belt 824 and the stack tray 821a or the stack tray 821b, and abuts the leading end of the sheet against the stopper 825. The knurled belt 824 is attached so as to come into contact with the uppermost surface of the sheet when the stack tray 821 is in the sheet receiving position.

  A gripper 830 that grips the leading end of the sheet and conveys the sheet is attached to the driving belt 831 in a state where the gripper 830 is pressurized by a spring (not shown) in the direction of closing the mouth, and a driving device (not shown). Open the mouth. The driving belt 831 is driven by a driving device (not shown) and rotates clockwise. By driving the drive belt 831, the sheet whose leading end is gripped by the gripper 830 is conveyed from the exit of the conveyance path 813 onto the stack tray 821 a or the stack tray 821 b.

  The dolly 820 conveys the sheets stacked together with the stack tray 821. The dolly 820 includes four casters, one at each of the four corners, and can transport the sheet separately from the stacker 800.

  When taking out the sheets stacked on the stack tray 821a or the stack tray 821b, the stacker control unit 801 lowers the stack tray 821a or the stack tray 821b or both trays by a motor (not shown). Then, the stacker control unit 801 stops the stack tray 821a or the stack tray 821b at a lower limit position further lowered by a predetermined distance from the position detected by the full load position detection sensor 817a or the full load position detection sensor 817b. When the door of the stacker 800 is opened and the dolly 820 is pulled out while stopped at the lower limit position, the sheet stack is pulled out together with the stack tray 821, and the sheets can be transported. In this way, the sheets stacked on the stack tray can be taken out.

(Operation display device)
FIG. 4 is a front view showing the appearance of the operation display device 400. The operation display device 400 is provided with a start button 402 for starting an image forming operation, a stop key 403 for interrupting the image forming operation, and numeric keys 404 to 412 and 414 for setting numerical values. The operation display device 400 is also provided with a clear key 415, a reset key 416, and the like.

  In addition, a liquid crystal display unit 420 having a touch panel is disposed on the operation display device 400. A soft key is arranged on the screen of the liquid crystal display unit 420.

  The image forming apparatus has various processing modes such as non-sorting, group sorting, and shift sorting as post-processing modes. These processing modes are set by an input operation from the operation display device 400. For example, when setting the post-processing mode, if the “sorter” key 413 that is a soft key is selected on the initial screen shown in FIG. 4, a menu selection screen is displayed on the liquid crystal display unit 420. Then, the processing mode is set using this menu selection screen. In addition, the liquid crystal display unit 420 is provided with a user mode key 417 for performing various settings of the apparatus.

(Basic stacker operation)
The basic operation of the stacker 800 will be described with reference to FIGS. 5 and 6 are diagrams illustrating the operation of the stacker 800. FIG. 7 to 9 are diagrams showing the operation in the stack unit 810. Before the sheet S is conveyed from the image forming apparatus 10 to the stacker 800, the CPU circuit unit 150 in the image forming apparatus 10 selects one of the two stacking modes according to the size of the sheet, and stacker control is performed on the selected stacking mode. Section 801 is notified and sheet stacking control is performed.

  When stacking sheets whose length in the transport direction is less than 230 mm, the stacker 800 stacks sheets in the order of the stack tray 821b and the stack tray 821a (first stacking mode). FIG. 10 is a diagram illustrating an operation in the stack unit 810 when sheets are stacked in the first stacking mode.

  When stacking sheets having a length of 230 mm or more in the transport direction, the stacker 800 stacks sheets across the stack trays 821a and 821b (second stacking mode). FIG. 11 is a diagram illustrating an operation in the stack unit 810 when sheets are stacked in the second stacking mode. In the second stacking mode, when the stack trays 821a and 821b are moved up and down, the stacker control unit 801 performs the lift control by completely synchronizing the positions and speeds of both trays.

  When executing the first stacking mode, the stacker 800 first stacks sheets on the stack tray 821b. Then, when it is detected by the full load position detection sensor 817b that the stack tray 821b is lowered to the full load position, the stacker 800 next stacks the stack tray 821a.

  Next, the loading operation in the first loading mode will be described in detail.

(Preparing tray loading)
When the stacking on the stack tray 821b is confirmed, the image forming apparatus 10 notifies the stacker 800 of size information and paper discharge destination information which are notified in advance before the sheet conveyance into the stacker 800 is started. Based on the information, the stacker 800 moves the width direction sheet regulating member 822 to a predetermined position corresponding to the sheet size, and performs a stacking preparation process for moving the leading sheet regulating unit 823 above the stack tray 821b.

  In the stacking preparation process, as shown in FIG. 5A, the stacker 800 moves the stack trays 821a and 821b to the arrows in the drawing so that the leading end sheet regulating unit 823 and the width direction sheet regulating member 822 do not interfere with the stack trays 821a and 821b. Descent in the direction. Thereafter, as shown in FIG. 5B, the stacker 800 moves the leading sheet regulating unit 823 and the width direction sheet regulating member 822, and then moves the stack tray 821 to a position where the top surface of the tray is detected by the paper surface detection sensor 816. Raise in the direction of the arrow in the figure. However, if one of the stack trays 821a and 821b is being lowered before the stacking preparation process, the leading sheet regulating unit 823 and the width direction sheet regulating member 822 are moved to the descending stack tray. It will not be raised according to.

(Tray loading operation)
As shown in FIG. 6A, the sheet S discharged from the apparatus main body of the image forming apparatus 10 is conveyed to a conveyance path 811 of the stacker 800 and is conveyed into the stacker 800 by a pair of rollers provided in the conveyance path 811. .

  When the sheet S reaches the lateral registration correction device 850 through the conveyance path 811, the lateral registration correction device 850 corrects the lateral registration of the sheet S.

  As shown in FIG. 6B, in the state where the conveyance roller 851 and the conveyance roller 852 incorporated in the horizontal registration correction device 850 sandwich the sheet, the horizontal registration correction device 850 is moved in the conveyance direction by a motor (not shown). The sheet is shifted by moving in the width direction perpendicular to the sheet. The stacker 800 detects the edge of the sheet by a sensor (not shown), and corrects the difference between the position of half the paper width from the conveyance center and the detected position of the edge of the sheet. The correction device 850 is moved to correct the deviation of the lateral registration of the sheet.

  Further, when the shift sort mode is set in the operation display device 400, the lateral registration correction device 850 adds the shift amount of the bundle toward the front side or the rear side in addition to the lateral registration shift amount, and shifts the sheet. Let

  As shown in FIG. 7, the sheet S is conveyed to the stack unit 810 through a conveyance path 813. As shown in FIG. 8A, the sheet S conveyed to the stack unit 810 is gripped by the gripper 830 that has been waiting as the sheet S enters the stack unit 810. After gripping the sheet S, the drive belt 831 is driven to convey the sheet S toward the stack tray 821b.

  When the sheet S approaches the leading sheet regulation unit 823, the gripper 830 opens the mouth by a load (not shown) and releases the sheet S as shown in FIG. 8B. As shown in FIG. 8C, the sheet S falls on the uppermost surface of the stack tray 821b while proceeding in the conveyance direction due to inertia. Thereafter, the sheet S is conveyed by the knurled belt 824 toward the stopper 825 while sliding on the uppermost surface of the stack tray 821b.

  Then, as illustrated in FIG. 8D, the sheet S is abutted against the stopper 825 by the knurled belt 824 and stops. The width direction sheet regulating member 822 performs the alignment operation of the sheets S in a direction perpendicular to the sheet conveying direction (the sheet width direction), and aligns the side edges of the sheets. After the stacking is completed, the stacker 800 performs an operation of lowering the stack tray 821b to a certain distance by a load (not shown) so that the uppermost surface of the stack tray 821b becomes constant by the paper surface detection sensor 816.

  As shown in FIG. 9A, when the sheets are stacked on the stack tray 821b and the full load position detection sensor 817b detects that the stack tray 821b is lowered to the lower limit position, the stack tray 821b becomes full. The stacker 800 switches the sheet stacking destination to the stack tray 821a.

  As shown in FIG. 9B, the stacking preparation processing for switching the discharge destination from the stack tray 821b to the stack tray 821a is performed based on size information and discharge destination information notified in advance. That is, the stacker 800 moves the width direction sheet regulating member 822 and lowers the stack tray 821a and the stack tray 821b by a predetermined amount so as not to interfere with the stack tray 821 when the leading sheet regulating unit 823 is moved. Thereafter, the stacker 800 moves the leading edge sheet regulating unit 823 above the stack tray 821a.

  When the movement of the leading edge sheet regulating unit 823 is finished, the stacker 800 raises the stack tray 821a to a position where the uppermost surface is detected by the paper surface detection sensor 816, as shown in FIG. 9C.

  As shown in FIGS. 9D and 10, when the movement of the leading sheet regulating unit 823 is completed and the stack tray 821a is raised to the uppermost surface, the stacker 800 starts stacking on the stack tray 821a. The flow of stacking sheets on the stack tray 821a is the same as the flow of stacking sheets on the stack tray 821b.

  On the other hand, when the second stacking mode is executed, as shown in FIG. 11, the stacker 800 synchronizes the driving of the stack tray 821a and the stack tray 821b so that the sheets are stacked. Then, the stacker 800 moves the leading edge sheet regulating unit 823 to a position that regulates the leading edge in the sheet conveyance direction. The flow of sheet stacking is the same as that in the first stacking mode described above.

(Tray removal operation)
The tray removal operation of the stacker 800 will be described with reference to FIGS. FIG. 12 is a view showing the appearance of the stacker 800. 13 to 15 are diagrams showing the internal operation of the stacker 800. FIG. The front surface of the stacker 800 is covered with a cover 840 (cover member). An extraction switch 841 is disposed on the cover 840. The take-out switch 841 includes two take-out switches 841a for instructing start of take-out of the stack tray 821a and take-out switches 841b for instructing start of take-out of the stack tray 821b.

  An operation of taking out the stack tray 821a when performing a stacking operation from the image forming apparatus 10 to the stack tray 821a of the stacker 800 will be described. As shown in FIG. 13A, when the stack tray 821a is taken out while the stack tray 821a is being loaded, the user presses the take-out switch 841a.

  When the takeout switch 841a is pressed, the takeout request is notified to the image forming apparatus 10 via the stacker control unit 801. When the CPU circuit unit 150 in the image forming apparatus 10 recognizes the take-out request, the CPU circuit unit 150 stops the image forming operation in order to temporarily interrupt the stacking operation on the stack tray 821a.

  As shown in FIG. 13B, when the stacking of the last sheet S1 on which the image has been formed before the interruption is completed on the stack tray 821a, the stacker 800 confirms the completion of the stacking of the sheet S1 via the stacker control unit 801. 10 is notified. Then, the stacker 800 enters a removal process waiting state in which the stack tray 821a can be removed and lowered.

  When the CPU circuit unit 150 in the image forming apparatus 10 recognizes the completion of stacking of the sheets S1, the CPU circuit unit 150 notifies the stacker 800 of permission to take out the stack tray 821a.

  When the stacker 800 receives permission from the image forming apparatus 10, the stacker 800 notifies the image forming apparatus 10 of unloadable information prohibiting stacking on the stack tray 821 a that is permitted to be removed. When the image forming apparatus 10 receives the information indicating that the stacking is impossible, the image forming apparatus 10 prohibits the start of sheet discharge to the stacker 800. That is, the image forming apparatus 10 prohibits the start of the image forming operation.

  Then, as shown in FIG. 14A, the stack tray 821a starts the tray lowering operation and is in the process of taking out. As shown in FIG. 14B, the stack tray 821a stops at a lower limit position further lowered by a predetermined distance from the position detected by the full load position detection sensor 817a, and is set in the dolly 820. Thereafter, the cover 840 is opened.

  On the other hand, when the image forming apparatus 10 recognizes the stacking prohibition information by the CPU circuit unit 150, the stacking operation on the stack tray 821a is temporarily prohibited while the stacking prohibition information is set. The start of discharge is prohibited.

  As shown in FIG. 15A, when the stacker 800 detects that the bundle loaded on the stack tray 821a is removed by the sheet presence / absence detection sensor 818a when the user closes the cover 840, the following operation is performed. I do. The stacker 800 starts an initialization operation for moving the leading sheet restriction unit 823, the width direction sheet restriction member 822, and the stack tray 821 to the home position.

  As shown in FIG. 15B, when the width-direction sheet regulating member 822 and the stack tray 821 reach the home position, the initialization operation is completed. The stacker 800 notifies the image forming apparatus 10 of the completion of the removal operation of the stack tray 821a that has been removed, and the release of the non-ejection information that prohibits the ejection to the stack tray 821a that has been ejected. Exit from the extraction process.

  As a result, the image forming apparatus 10 recognizes that the removal operation of the removed stack tray 821a has been completed by the CPU circuit unit 150, and puts the stacking on the stack tray 821a in a permitted state. When this stacking is permitted, the temporarily interrupted image forming operation is started, and the sheet stacking operation is resumed.

  If the takeout switch 841a is pressed while the stack tray 821a is not being loaded, the CPU circuit unit 150 in the image forming apparatus 10 immediately takes out the takeout request notified from the stacker 800. The permission is notified to the stacker 800. As a result, the take-down operation of the stacker 800 is started.

  Further, the stack tray 821b is taken out in the same flow as the stack tray 821a by pressing the take-out switch 841b.

  Further, in the first stacking mode, if the stack tray 821b is removed during the stacking operation on the stack tray 821a, the continuity that allows the stack tray 821b to be removed while continuing the stacking operation of the stack tray 821a. Ass operation is performed. FIG. 16 is a diagram showing an internal operation of the stacker 800 when the stack tray 821b is taken out during the stacking operation on the stack tray 821a. Similarly, the stack tray 821a can be taken out during the stacking operation on the stack tray 821b.

  Further, in the second stacking mode, when the user performs the extraction with the sheets stacked on the stack tray 821a and the stack tray 821b, the user presses either the extraction switch 841a or the extraction switch 841b. As a result, the take-out request is notified from the stacker 800 to the image forming apparatus 10 via the stacker control unit 801.

  When the CPU circuit unit 150 in the image forming apparatus 10 recognizes the take-out request, the CPU circuit unit 150 stops the image forming operation in order to temporarily interrupt the stacking operation on the stack tray 821. Further, when the CPU circuit unit 150 in the image forming apparatus 10 recognizes the completion of stacking of the last sheet being conveyed, the CPU circuit unit 150 notifies the stacker 800 of permission to take out the stack tray 821a and the stack tray 821b.

  The stacker 800 starts to take out and lower the stack tray 821a and the stack tray 821b. The lowering operation of the stack trays 821a and 821b is performed in the same flow as in the case of the stack tray 821a by completely synchronizing the positions and speeds of both trays.

  As described above, in the stacker 800, the operation of taking out the stack tray 821 is started when the user presses the take-off switch 841 at an arbitrary timing.

  Further, the start of the stacking operation on the stack trays 821a and 821b and the switching of the discharge destination between the stack tray 821a and the stack tray 821b also occur at an arbitrary timing depending on the printing status of the image forming apparatus 10.

  For this reason, there is a case where the start of a print job for stacking sheets on the stack tray 821b that is not the target of extraction is instructed in the state where the extraction processing of the stack tray 821a is being performed when the extraction operation is started by pressing the extraction switch 841a. . That is, the timing at which the tray removal process and the stack preparation process overlap occurs.

  When the print start is permitted without considering the timing at which the tray removal process and the stack preparation process accompanying the start of the print job overlap, the stack preparation process is performed with the cover 840 opened, and the user moves in the stack preparation process. There is a risk of touching.

  Therefore, in this embodiment, one of two types of priority control is performed when the tray is taken out. In the first priority control, in either state of the stack trays 821a and 821b, a print job to the stack unit 810 is prohibited in the state where the take-down operation is started. That is, the sheet stacking preparation process is not performed during the lowering operation of the stack tray 821.

  In the second priority control, even if one of the stack trays 821a and 821b is in the state of being taken out, a print job to the stack unit 810 is permitted before the cover 840 is opened. That is, the tray take-out process is temporarily interrupted, and the sheet stacking preparation process is preferentially performed.

  Then, the stacking preparation process is preferentially performed, and after the sheet stacking operation on the other stack tray 821 that is not the target of extraction is started, the tray extraction process of the stack tray 821 that is the target of extraction is resumed. Therefore, the stacking preparation process is not performed with the cover 840 opened.

  As described above, the two types of priority control can prevent the user from touching the moving unit in the stacking preparation process with the cover 840 opened.

  Next, user operability in the first priority control and the second priority control will be described. The first priority control (tray removal priority control) has an advantage that the removal of the stack tray 821 is accelerated because priority is given to the tray removal process. However, there is a demerit that a print job to the stack unit 810 cannot be started even if there is a stackable stack tray 821 until the user completes the operation of taking out the stack tray 821 and closes the cover 840.

  On the other hand, the second priority control (print priority control) has the following merits because the stacking preparation process is preferentially processed even during the take-out process. That is, there is an advantage that the print operation can be continued without stopping the image forming system by processing the print job to the stack unit 810 without stopping the entire system. However, there is a demerit that the user waits for the tray removing operation until the stacking preparation process is completed.

(Select tray control)
As described above, since the two priority controls have advantages and disadvantages, it is important from the viewpoint of user operability to be able to select two take-out controls according to the user's needs. That is, the first priority control is performed for a user who wants to quickly take out the tray to be taken out, and the first priority control is performed for the user who wants to continue the stacking operation even after waiting for the taking out operation. It is important to perform the second priority control.

  In this embodiment, the user can arbitrarily manually select one of the two priority controls. When the user presses a “user mode” key 417 that is a soft key on the liquid crystal display unit 420 (see FIG. 4), the screen shown in FIG. 17 is displayed on the liquid crystal display unit 420. FIG. 17 is a diagram showing a tray removal mode setting screen displayed on the liquid crystal display unit 420. On this tray take-out mode setting screen, a “print priority” soft key 501, a “pickout priority” soft key 502, a “cancel” soft key 503, and an “OK” soft key 504 are arranged.

  When the user presses the “pickout priority” soft key 502 to complete the setting, the above-described first priority control (tray removal priority control) that prioritizes tray removal is set.

  Further, when the user presses the “print priority” soft key 501 to complete the setting, second priority control (print priority control) that prioritizes continuation of tray stacking is set.

  The information set here is stored in the RAM 153 in the CPU circuit unit 150 and notified to the stacker 800 via the stacker control unit 801. Note that the set information is retained by a known backup method such as writing to a nonvolatile memory before the power is turned off.

  Next, the above two priority controls in the image forming system of the present embodiment will be described with reference to flowcharts.

(Tray removal priority control)
FIG. 18 is a flowchart showing a tray removal priority control procedure. This processing program is stored in the ROM 152 in the CPU circuit unit 150 and executed by the CPU 151. Here, a case where a print job is input in a state where the stacking operation on the stacker 800 is not performed will be described as an example.

  First, the CPU circuit unit 150 receives job settings input by the user via the liquid crystal display unit 420, and stores various information such as the number of entries and the paper discharge destination in the RAM 153 (step S1). The job settings include sheet size information (size type information in the case of a standard form), information on material types such as “plain paper” and “coated paper”, number of settings, duplex setting, and the like.

  The CPU circuit unit 150 waits until the user presses the start button 402 of the operation display device 400 (step S2). When the CPU circuit unit 150 detects that the start button 402 has been pressed by the user, the CPU circuit unit 150 determines whether or not the extraction process is being performed based on the stacking disabling information of both trays 821a and 821b (step S3). .

  This stacking impossibility information is notified from the stacker control unit 801 to the CPU circuit unit 150 when the user depresses one of the ejection switches 841a and 842b and the tray ejection process is started by the tray ejection operation described above. Note that this stacking impossibility information is notified even when the stack tray 821 on one side is taken out.

  When the CPU circuit unit 150 determines that the take-out process is not being performed based on the loading impossibility information, the CPU circuit unit 150 proceeds to the process of step S9. On the other hand, if it is determined that the extraction process is being performed, the CPU circuit unit 150 determines that the stack unit stacking job is based on the discharge destination information of the job input in step S2, and determines that the stack print job is to be stacked on the stack unit 810. The job start is suspended (step S4). That is, in the process of step S4, the CPU circuit unit 150 prohibits the stacking of sheets from the image forming apparatus 10 onto the stack trays 821a and 821b in the stack unit 810.

  When the lowering operation of the stack tray 821 designated by the take-out switches 841a and 842b is completed via the stacker control unit 801, the CPU circuit unit 150 permits the opening operation of the cover 840 and waits for the cover 840 to open ( Step S5). When the user opens the cover 840, the CPU circuit unit 150 waits for the cover 840 to close via the stacker control unit 801 (step S6). The permission to open the cover 840 is given by notification by display or sound, unlocking of the cover, or the like.

  When the cover 840 is closed by the user, the CPU circuit unit 150 instructs the stacker control unit 801 to start the initialization operation of the stack unit 810 (step S7). After receiving the instruction to start the initialization operation, the stacker control unit 801 notifies the CPU circuit unit 150 of the cancellation of the stacking disabling information of both trays and the completion of initialization when the initialization of the stacker 800 is completed.

  The CPU circuit unit 150 waits for the completion of initialization of the stack unit 810 and the release of the unloadable information via the stacker control unit 801 (step S8).

  When the CPU circuit unit 150 receives initialization completion of the stack unit 810 and release of the stacking disabling information, the CPU circuit unit 150 instructs the stacker 800 via the stacker control unit 801 to prepare for stacking stacking of a pending job ( Step S9). As a result, the stacker 800 starts the stack unit loading preparation.

  The CPU circuit unit 150 waits for the stack unit stacking preparation completion via the stacker control unit 801 (step S10). When the CPU circuit unit 150 recognizes that the stack unit stacking preparation is completed, it causes the stacker 800 to start a printing operation (step S11). Thereafter, the CPU circuit unit 150 ends this process.

  As described above, in the tray take-out priority control, when the take-out switch 841 is pressed and the take-out operation is started, the take-out process can be preferentially performed by holding the start of the stack unit stacking job.

  In addition, by suspending the start of the stack unit stacking job, it is possible to prevent the stacking preparation process from being performed while the cover 840 is open. Thus, the CPU circuit unit 150 functions as a control unit of the present invention.

(Print priority control)
19 and 20 are flowcharts showing the print priority control procedure. This processing program is stored in the ROM 152 in the CPU circuit unit 150 and executed by the CPU 151. Here, a case where a print job is input in a state where the stacking operation on the stacker 800 is not performed will be described as an example.

  First, the CPU circuit unit 150 receives job settings input by the user via the liquid crystal display unit 420, and stores various information such as the number of entries and the paper discharge destination in the RAM 153 (step S21). The job settings include sheet size information (size type information in the case of a standard form), information on material types such as “plain paper” and “coated paper”, number of settings, duplex setting, and the like.

  The CPU circuit unit 150 waits until the user presses the start button 402 of the operation display device 400 (step S22). The pressing of the start button 402 is an example of a sheet stacking recognition unit that recognizes a request to start stacking sheets. When the CPU circuit unit 150 detects that the start button 402 has been pressed by the user, the CPU circuit unit 150 determines whether or not the extraction process is being performed based on the stacking disabling information of both trays 821a and 821b (step S23). .

  This stacking impossibility information is notified from the stacker control unit 801 to the CPU circuit unit 150 when the user depresses one of the ejection switches 841a and 842b and the tray ejection process is started by the tray ejection operation described above.

  If the CPU circuit unit 150 determines that the take-out process is not being performed based on the loading impossibility information, the process proceeds to step S40. On the other hand, if it is determined that the removal process is being performed, the CPU circuit unit 150 outputs the stack tray 821 notified of the stacking impossible information via the stacker control unit 801 and the discharge destination information of the stack unit stacking job input in step S22. Are compared (step S24).

  If the stack tray 821 to be discharged coincides with the stack tray 821 being taken out, the CPU circuit unit 150 proceeds to the process of step S35 and suspends the start of stack stack printing.

  On the other hand, if the stack tray 821 that is the paper discharge destination does not match the stack tray 821 that is being removed in step S24, the CPU circuit unit 150 performs the following operation. That is, the CPU circuit unit 150 determines whether or not the operation of taking out and lowering the stack tray 821 designated by the takeout switch 841 is completed via the stacker control unit 801 and the cover 840 is opened (step S25).

  When determining that the cover 840 is open, the CPU circuit unit 150 proceeds to the process of step S35. On the other hand, when the cover 840 is closed and it is determined that the cover is being removed, the CPU circuit unit 150 performs the following operation. In other words, the CPU circuit unit 150 instructs the stacker control unit 801 to stop the lowering operation of the stack tray 821 that has been instructed to be ejected to the stacker 800, and temporarily suspends the ejecting process (step S26).

  The CPU circuit unit 150 instructs the stacker 800 via the stacker control unit 801 to prepare for stacking the stack unit 810 (step S27). As a result, the stacker 800 starts the stack unit loading preparation.

  The CPU circuit unit 150 waits until the stack unit stacking preparation is recognized through the stacker control unit 801 (step S28). When the CPU circuit unit 150 recognizes that the stack unit stacking preparation is completed, the CPU circuit unit 150 causes the stacker 800 to start a printing operation on the stack unit 810 input in step S22 (step S29).

  The CPU circuit unit 150 instructs the stacker 800 to resume the interrupted extraction process via the stacker control unit 801 (step S30). Then, the CPU circuit unit 150 waits for the completion of the operation of taking out and lowering the stack tray 821 designated by the take-out switches 841a and 842b through the stacker control unit 801 and opening the cover 840 (step S31).

  When the user opens the cover 840, the CPU circuit unit 150 waits for the cover 840 to close via the stacker control unit 801 (step S32).

  When the cover 840 is closed by the user, the CPU circuit unit 150 instructs the stacker control unit 801 to start the initialization operation of the stack unit 810 (step S33). After receiving the instruction to start the initialization operation, the stacker control unit 801 notifies the CPU circuit unit 150 of the cancellation of the stacking disabling information of both trays and the completion of initialization when the initialization of the stacker 800 is completed.

  The CPU circuit unit 150 waits for completion of initialization of the stack unit 810 and release of the unloadable information via the stacker control unit 801 (step S34). When the initialization of the stack unit 810 and the release of the unloadable information are received, the CPU circuit unit 150 ends this process.

  On the other hand, if it is determined in step S24 that the stack tray 821 that is the paper discharge destination does not match the stack tray 821 that is being removed, or if it is determined in step S25 that the cover 840 is open, the CPU circuit unit 150 performs the following operation. Perform the correct operation. That is, the CPU circuit unit 150 determines that the tray removal process has already started at the paper discharge destination of the stack unit stacking job input in step S22, and suspends the start of the input stack unit stacking print job. (Step S35).

  When the stack tray 821 specified by the take-out switches 841a and 842b is completed via the stacker control unit 801, the CPU circuit unit 150 permits the cover 840 to be opened and waits for the cover 840 to open. (Step S36).

  When the user opens the cover 840, the CPU circuit unit 150 waits for the cover 840 to close via the stacker control unit 801 (step S37).

  When the cover 840 is closed by the user, the CPU circuit unit 150 instructs the stacker control unit 801 to start the initialization operation of the stack unit 810 (step S38). After receiving the instruction to start the initialization operation, the stacker control unit 801 notifies the CPU circuit unit 150 of the cancellation of the unloadable tray stacking information and the completion of initialization when the stacker 800 is initialized.

  The CPU circuit unit 150 waits for the completion of initialization of the stack unit 810 and release of the unloadable information on the take-out tray via the stacker control unit 801 (step S39).

  When the CPU circuit unit 150 receives initialization completion of the stack unit 810 and release of the stacking disabling information, the CPU circuit unit 150 instructs the stacker 800 via the stacker control unit 801 to prepare for stacking stacking of a pending job ( Step S40). As a result, the stacker 800 starts the stack unit loading preparation.

  The CPU circuit unit 150 waits for the stack unit stacking preparation completion via the stacker control unit 801 (step S41). When the CPU circuit unit 150 recognizes that the stack unit stacking preparation is completed, it causes the stacker 800 to start a printing operation (step S42). Thereafter, the CPU circuit unit 150 ends this process.

  In this print priority control, even when the takeout switch 841 is pressed and the takeout process is started, if the paper discharge destination of the input stack unit stacking job does not match the stack tray 821 being taken out, the following is performed. Operation is performed. That is, before the cover 840 is opened, the printing process can be continued by preserving the take-out process and preferentially performing the stacking preparation process. As a result, the printing process can be started earlier than the take-out priority control by the user's take-out work time.

  Further, by holding the take-out process and performing the stacking preparation process with priority on the printing operation, it is possible to prevent the stacking preparation process from being performed while the cover 840 is open. Thus, the CPU circuit unit 150 functions as a control unit of the present invention.

(Selection process)
FIG. 21 is a flowchart showing a selection processing procedure for selecting print priority control or tray ejection priority control. This processing program is stored in the ROM 152 in the CPU circuit unit 150, and is executed by the CPU 151 when the user presses the “user mode” soft key displayed on the liquid crystal display unit 420.

  First, the CPU circuit unit 150 displays a tray removal mode setting screen (see FIG. 17) on the liquid crystal display unit 420 (step S51). The CPU circuit unit 150 waits until any of the soft keys displayed on the tray removal mode setting screen is pressed (step S52).

  When the user presses the soft key, the CPU circuit unit 150 determines whether the “print priority” soft key 501 is pressed and then the “OK” soft key 504 is pressed (step S53). . When the “print priority” soft key 501 is pressed, the CPU circuit unit 150 selects print priority control (step S54). Thereafter, the CPU circuit unit 150 ends this process.

  On the other hand, if the “print priority” soft key 501 has not been pressed in step S53, the CPU circuit unit 150 has pressed the “pickout priority” soft key 502 and subsequently pressed the “OK” soft key 504. It is determined whether or not (step S55). When the “pickout priority” soft key 502 is pressed, the CPU circuit unit 150 selects takeout priority control (step S56). Thereafter, the CPU circuit unit 150 ends this process.

  On the other hand, if the “pickout priority” soft key 502 is not pressed in step S55, the CPU circuit unit 150 assumes that only the “cancel” soft key 503 or simply the “OK” soft key 504 is pressed. Return to the previous screen (step S57). Thereafter, the CPU circuit unit 150 ends this process.

  In this way, the user can select and execute one of the two take-out controls according to the needs.

  As described above, the stacker 800 according to the present embodiment includes the plurality of stack trays 821a and 821b, the cover 840 that can be opened and closed to cover them, and the like. For example, when the stack tray 821b is taken out, the stacker 800 performs a continuous operation that allows the stack tray 821b to be taken out while continuing the stacking operation of the stack tray 821a.

  Further, the stacker 800 arranges a plurality of stacking trays in the sheet conveyance direction so as to be selectively used according to the length of the sheet, and effectively uses the space in the apparatus. Further, if the stacker 800 has a sheet size that can be stacked on one stacking tray, a stacking operation on the other stacking tray is continued even during the take-out process, so that a large number of sheets can be stored without stopping the apparatus. Continue loading.

  Further, the stacker 800 can prevent the stacking preparation process from being performed with the cover open even when the extraction process and the stacking preparation process overlap, by the two tray removal controls of the tray ejection priority control and the print priority control. .

  In addition, the stacker 800 gives priority to tray removal control for a user who wants to stop sheet stacking and quickly perform an extraction operation in accordance with user needs. On the other hand, the stacker 800 gives priority to print control to a user who wants to continue the printing operation and continue to stack the sheets even after waiting for the take-out operation. By selecting one of the two take-out controls in this way, the user operability is improved.

  Further, since alignment preparation is performed to align the sheets, the sheets stacked on the stack tray can be aligned, and the productivity and quality of the sheet bundle are improved. In addition, the height of the upper surface of the stack tray or the upper surface of the stacked sheets is detected, and the stack tray, which is the stacking position of the sheets, is moved to the sheet stacking position in advance, so that it is possible to quickly shift to the start of stacking sheets. it can. In addition, when the length of the sheet in the sheet conveyance direction is longer than the length that can be stacked on one stack tray, the stacked sheets are stacked across a plurality of stack trays. Can be increased.

  The present invention is not limited to the configuration of the above-described embodiment, and any configuration can be used as long as the functions shown in the claims or the functions of the configuration of the present embodiment can be achieved. Is also applicable.

  For example, in the above-described embodiment, the cover 840 has a single shape covering the front surface of the stack tray 821, but the present invention may have a cover structure in which two covers that individually cover the stack tray 821 a and the stack tray 821 b are open. Applied.

  Moreover, in the said embodiment, although the stack part was provided with two stack trays, it may be provided with three or more stack trays, and this invention is applicable similarly.

  In the above embodiment, the case where the stack tray 821a and the stack tray 821b are moved up and down is shown as the movement of the tray. However, the structure is configured to move in the width direction that is perpendicular to the sheet conveyance direction. However, the present invention is also applicable.

  In the above embodiment, the selection of “print priority control” or “tray ejection priority control” is performed by the user's pressing operation via the liquid crystal display unit 420, but the CPU circuit unit 150 is registered in advance, for example. You may make it select automatically according to conditions.

  Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device.

  In addition, the shapes of the component parts described in the above embodiment, the relative arrangement thereof, and the like should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions, and the scope of the present invention is described above. It is not limited only to what is illustrated.

  In the above-described embodiment, the monochrome image forming apparatus is described as the electrophotographic image forming apparatus. However, the image forming apparatus may be applied to a color image forming apparatus. The image forming apparatus is not limited to the electrophotographic system, and can be applied to various printing systems such as an inkjet system, a thermal transfer system, a thermal system, an electrostatic system, and a discharge destruction system.

  The material of the sheet is not particularly limited, such as a paper medium, an OHP sheet, or a cardboard paper. The shape of the sheet is not particularly limited, such as tab paper.

  In the above-described embodiment, the case where the sheet supply device is an image forming device has been described. However, the sheet stacking device of the present invention may be various devices that discharge sheets, for example, an optional device connected to the image forming device. Etc. can be connected. An example of such an optional device is a stapling device that binds a sheet on which an image is formed. Further, there are a folding device that folds the paper and a sorting device that sorts the paper. Further, there is a punching device that punches a binding hole in a sheet. Further, a cutting device that can cut a large amount of sheets at the same time can be mentioned.

10 Image forming apparatus 150 CPU circuit unit 800 Sheet stacking device (stacker)
801 Stacker control unit 816 Paper surface detection sensor 821, 821a, 821b Stack tray 822 Width direction sheet regulating member 823 Front end sheet regulating unit 840 Cover 841, 841a, 841b Removal switch

Claims (15)

Sheet conveying means for conveying the sheet discharged from the sheet supply device;
A plurality of sheet stacking means for stacking the sheets conveyed by the sheet conveying means;
Moving means for individually moving the plurality of sheet stacking means;
An openable / closable cover member for covering the plurality of sheet stacking means;
A plurality of sheet stacking means, and a takeout instruction means for individually giving a sheet takeout instruction,
When taking out is instructed by the take out instructing means, the instructed sheet stacking means is moved to a predetermined position, and when the sheet stacking means is moved to the predetermined position, a taking out process for permitting an opening operation of the cover member is performed. A sheet stacking device to perform,
A sheet stacking apparatus comprising: a control unit that prohibits the start of stacking of sheets on the sheet stacking unit when the extraction process of the sheet stacking unit specified by the extraction instructing unit is started. Sheet conveying means for conveying the sheet discharged from the sheet supply device;
A plurality of sheet stacking means for stacking sheets conveyed from the sheet conveying means;
Moving means for individually moving the plurality of sheet stacking means;
Sheet stacking recognition means for recognizing a request to start stacking sheets on the sheet stacking means;
An openable / closable cover member for covering the plurality of sheet stacking means;
A plurality of sheet stacking means, and a takeout instruction means for individually giving a sheet takeout instruction,
When taking out is instructed by the take out instructing means, the instructed sheet stacking means is moved to a predetermined position, and when the sheet stacking means is moved to the predetermined position, a taking out process for permitting an opening operation of the cover member is performed. A sheet stacking device to perform,
When the sheet stacking recognition unit recognizes a sheet stacking start request to the sheet stacking unit that has not been instructed to be fetched, the sheet stacking unit interrupts the fetching process and is requested to start stacking the sheet. A sheet stacking apparatus comprising: a control unit that restarts the take-out process after performing a preparatory process before stacking on the sheet. When the sheet stacking recognition unit recognizes a sheet stacking start request to the sheet stacking unit that has not been instructed to be fetched, the sheet stacking unit interrupts the fetching process and is requested to start stacking the sheet. Other control means for restarting the take-out process after performing the preparatory process before carrying on
The sheet stacking apparatus according to claim 1, further comprising a selection unit that selects one of the control unit and the other control unit. When the take-out process of the sheet stacking unit instructed by the take-out instructing unit is started, another control unit that prohibits the start of sheet stacking on the sheet stacking unit,
The sheet stacking apparatus according to claim 2, further comprising a selection unit that selects one of the control unit and the other control unit. Sheet conveying means for conveying the sheet discharged from the sheet supply device;
A plurality of sheet stacking means for stacking sheets conveyed from the sheet conveying means;
Moving means for individually moving the plurality of sheet stacking means;
Sheet stacking recognition means for recognizing a request to start stacking sheets on the sheet stacking means;
An openable / closable cover member for covering the plurality of sheet stacking means;
A take-out instruction means for individually giving a take-out instruction to the plurality of sheet stacking means;
When taking out is instructed by the take out instructing means, the instructed sheet stacking means is moved to a predetermined position, and when the sheet stacking means is moved to the predetermined position, a taking out process for permitting an opening operation of the cover member is performed. Control means to perform;
Have
The control means includes a first priority control for prohibiting the start of stacking of sheets on the sheet stacking means when the take-out operation of the sheet stacking means instructed by the take-out instruction means is started, and the sheet stacking recognition means When a request to start stacking sheets on the sheet stacking unit for which no takeout instruction has been issued is recognized, the takeout process is interrupted and the sheet stacking unit requested to start stacking the sheets is stacked. After performing the preparatory process, the second priority control for resuming the take-out process is selectively executed.
The sheet stacking apparatus further comprises a selection unit that manually selects one of the first priority control and the second priority control. An alignment means for aligning the sheets stacked on the sheet stacking means;
The control unit moves the alignment unit to a predetermined position as the preparation process in order to align the sheets stacked on the sheet stacking unit that is the stacking destination of the sheets recognized by the sheet stacking recognition unit. The sheet stacking apparatus according to claim 2. A height detecting means for detecting the height of the upper surface of the sheet stacking means or the upper surface of the stacked sheets;
In the preparation process, the control unit detects the height of the upper surface of the sheet stacking unit or the height of the stacked sheet upper surface by the height detection unit, and is a sheet stacking destination recognized by the sheet stacking recognition unit. 7. The sheet stacking apparatus according to claim 2, wherein the sheet stacking unit is moved to a sheet stacking position. A determination unit that determines whether or not the length of the sheets stacked in the sheet stacking unit is a length that can be stacked on one sheet stacking unit;
When the determining unit determines that the length of the stacked sheets in the sheet conveyance direction is a length that can be stacked on one sheet stacking unit, the moving unit moves the plurality of stacked sheets to the plurality of sheets. If the length of the stacked sheets in the sheet conveying direction is determined to be larger than the length that can be stacked on one sheet stacking unit, the stacked sheets are stacked. The sheet stacking apparatus according to claim 1, wherein the plurality of sheet stacking units are moved so as to stack sheets across the plurality of sheet stacking units.   The sheet stacking apparatus according to claim 1, wherein the sheet supply apparatus is an image forming apparatus. Sheet conveying means for conveying the sheet discharged from the sheet supply apparatus, a plurality of sheet stacking means for stacking the sheets conveyed by the sheet conveying means, and a moving means for individually moving the plurality of sheet stacking means; In a control method of a sheet stacking apparatus comprising: an openable / closable cover member for covering the plurality of sheet stacking means; and a takeout instruction means for individually giving a sheet takeout instruction to the plurality of sheet stacking means,
When taking out is instructed by the take out instructing means, the instructed sheet stacking means is moved to a predetermined position, and when the sheet stacking means is moved to the predetermined position, a taking out process for permitting an opening operation of the cover member is performed. Steps to do,
And a step of prohibiting the start of stacking of sheets on the sheet stacking unit when the extraction process of the sheet stacking unit specified by the extraction instructing unit is started. Sheet conveying means for conveying the sheet discharged from the sheet supply apparatus, a plurality of sheet stacking means for stacking the sheets conveyed from the sheet conveying means, and a moving means for individually moving the plurality of sheet stacking means; A sheet stacking recognizing unit for recognizing a request to start stacking sheets on the sheet stacking unit; an openable / closable cover member for covering the plurality of sheet stacking units; and taking out a sheet from the plurality of sheet stacking units. In a control method of a sheet stacking apparatus provided with a take-out instruction means for individually giving instructions,
When taking out is instructed by the take out instructing means, the instructed sheet stacking means is moved to a predetermined position, and when the sheet stacking means is moved to the predetermined position, a taking out process for permitting an opening operation of the cover member is performed. Steps to do,
When the sheet stacking recognition unit recognizes a sheet stacking start request to the sheet stacking unit that has not been instructed to be fetched, the sheet stacking unit interrupts the fetching process and is requested to start stacking the sheet. And a step of restarting the take-out process after performing a preparatory process before stacking on the sheet. Sheet conveying means for conveying the sheet discharged from the sheet supply apparatus, a plurality of sheet stacking means for stacking the sheets conveyed from the sheet conveying means, and a moving means for individually moving the plurality of sheet stacking means; A sheet stacking recognizing unit for recognizing a request to start stacking sheets on the sheet stacking unit; an openable / closable cover member for covering the plurality of sheet stacking units; and taking out a sheet from the plurality of sheet stacking units. In a control method of a sheet stacking apparatus provided with a take-out instruction means for individually giving instructions,
When taking out is instructed by the take out instructing means, the instructed sheet stacking means is moved to a predetermined position, and when the sheet stacking means is moved to the predetermined position, a taking out process for permitting an opening operation of the cover member is performed. A retrieval processing step to be performed;
A first priority control step for prohibiting the start of stacking of sheets on the sheet stacking unit when starting the operation of extracting the sheet stacking unit instructed by the extraction instructing unit;
In the take-out processing step, when the sheet stacking recognition unit recognizes a request to start stacking sheets on the sheet stacking unit that has not been instructed to take out, the picking-up process is interrupted and the sheet stacking start is requested. A second priority control step of restarting the take-out process after performing a preparatory process before stacking on the sheet stacking unit,
A method for controlling a sheet stacking apparatus, comprising: a selection step of selecting one of the first priority control step and the second priority control step according to selection by an operator. An image forming apparatus for forming an image on a sheet;
A sheet conveying unit configured to convey a sheet discharged from the image forming apparatus, a plurality of sheet stacking units configured to stack the sheets conveyed by the sheet conveying unit, and a moving unit configured to individually move the plurality of sheet stacking units. An openable / closable cover member for covering the plurality of sheet stacking means, and a takeout instruction means for individually instructing to take out sheets from the plurality of sheet stacking means. Then, the instructed sheet stacking unit is moved to a predetermined position, and when the sheet stacking unit is moved to the predetermined position, an image including a sheet stacking device that performs a take-out process that permits an opening operation of the cover member. A forming system,
An image forming system comprising: a control unit that prohibits the start of stacking of sheets on the sheet stacking unit when the extraction process of the sheet stacking unit specified by the extraction instructing unit is started. An image forming apparatus for forming an image on a sheet;
A sheet conveying unit configured to convey a sheet discharged from the image forming apparatus, a plurality of sheet stacking units configured to stack the sheets conveyed from the sheet conveying unit, and a moving unit configured to individually move the plurality of sheet stacking units. A sheet stacking recognizing unit for recognizing a sheet stacking start request to the sheet stacking unit, an openable / closable cover member for covering the plurality of sheet stacking units, and the sheet stacking unit with respect to the plurality of sheet stacking units. A take-out instruction unit that individually issues a take-out instruction, and when the take-out instruction is instructed, the instructed sheet stacking unit is moved to a predetermined position, and the sheet stacking unit is moved to the predetermined position. An image forming system including a sheet stacking device that performs a take-out process that permits an opening operation of the cover member,
When the sheet stacking recognition unit recognizes a sheet stacking start request to the sheet stacking unit that has not been instructed to be fetched, the sheet stacking unit interrupts the fetching process and is requested to start stacking the sheet. An image forming system comprising: a control unit that resumes the take-out process after performing a preparatory process before stacking on the image forming apparatus. An image forming apparatus for forming an image on a sheet;
Sheet conveying means for conveying the sheet discharged from the image forming apparatus;
A plurality of sheet stacking means for stacking sheets conveyed from the sheet conveying means;
Moving means for individually moving the plurality of sheet stacking means;
Sheet stacking recognition means for recognizing a request to start stacking sheets on the sheet stacking means;
An openable / closable cover member for covering the plurality of sheet stacking means;
A take-out instruction means for individually giving a take-out instruction to the plurality of sheet stacking means;
When taking out is instructed by the take out instructing means, the instructed sheet stacking means is moved to a predetermined position, and when the sheet stacking means is moved to the predetermined position, a taking out process for permitting an opening operation of the cover member is performed. Control means to perform;
An image forming system comprising:
The control means includes a first priority control for prohibiting the start of stacking of sheets on the sheet stacking means when the take-out operation of the sheet stacking means instructed by the take-out instruction means is started, and the sheet stacking recognition means When a request to start stacking sheets on the sheet stacking unit for which no takeout instruction has been issued is recognized, the takeout process is interrupted and the sheet stacking unit requested to start stacking the sheets is stacked. After performing the preparatory process, the second priority control for resuming the take-out process is selectively executed.
The image forming system further comprises a selection unit that manually selects one of the first priority control and the second priority control.