JP2019156507A - Post-processing device and method of controlling post-processing device - Google Patents

Abstract

To provide a post-processing device capable of stably stacking formed sheet bundles, and a method of controlling the post-processing device.SOLUTION: A post-processing device 3 comprises: a stapler part 33 which binds a plurality of sheets to form a sheet bundle; an alignment/discharge part 34 which discharges the sheet bundle formed by the stapler part 33; and a sheet discharge tray 35 on which the sheet bundle discharged by the alignment/discharge part 34 is stacked. The post-processing device 3 counts a number of sheet bundles stacked on the sheet discharge tray 35 or the sheets constituting the sheet bundles stacked on the sheet discharge tray 35, and determines that the sheet discharge tray 35 is full when a count value reaches a reference value. The post-processing device 3 sets the reference value based upon a state of curling that the sheets constituting the sheet bundle discharged by the alignment/discharge part 34 is estimated to have and a kind of binding that the stapler part 33 has done.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a post-processing apparatus and a control method for the post-processing apparatus. More specifically, the present invention relates to a post-processing apparatus that can stably stack a generated sheet bundle and a control method for the post-processing apparatus.

  The electrophotographic image forming apparatus includes a scanner function, a facsimile function, a copying function, a function as a printer, a data communication function, and a server function, an MFP (Multi Function Peripheral), a facsimile apparatus, a copying machine, a printer, and the like. is there.

  In general, an image forming apparatus develops an electrostatic latent image formed on an image carrier by a developing device to form a toner image, transfers the toner image to a recording medium, and then fixes the toner image on a sheet by a fixing device. By doing so, an image is formed on the recording medium. In some image forming apparatuses, the electrostatic latent image formed on the photoreceptor is developed by a developing device to form a toner image, and the toner image is transferred to an intermediate transfer belt using a primary transfer roller. There is also a secondary transfer roller that secondarily transfers a toner image on an intermediate transfer belt to a recording medium.

  A post-processing apparatus that performs post-processing on a sheet is known. The post-processing apparatus is usually attached to the image forming apparatus, and performs post-processing on the paper printed by the image forming apparatus. Processes that can be executed by the post-processing device include a process of binding a plurality of sheets at the center and folding them in half, a Z-folding process for folding a large page into a Z-shape, a process for punching a sheet, or a plurality of processes There is a binding process for generating a bundle of sheets by binding sheets.

  In general, the post-processing apparatus is provided with a paper discharge tray that can be moved up and down to stack post-processed sheets. The height of this type of paper discharge tray is controlled so that the distance in the height direction between the top surface of the paper stacked on the paper discharge tray and the paper discharge port in the post-processing device is constant. Is done. Accordingly, the sheet discharge tray descends as the number of sheets discharged from the discharge port and stacked on the sheet discharge tray increases. Then, when it is detected that the discharge tray has been lowered to the predetermined lower limit position, the post-processing device detects that the tray is full (the discharge tray is full). When the tray full is detected, the post-processing device immediately displays a warning on the operation panel regardless of the remaining number of prints, and stops the printing operation. As a result, new paper is not discharged to the paper discharge tray, and a situation where an excessive amount of paper is stacked in an unstable state on the paper discharge tray is avoided.

  By the way, when the post-processing device continuously generates a side-stitched sheet bundle and stacks and stacks them on the discharge tray, the local bulge of the sheet bundle due to the overlap of the needles is accumulated and the sheet bundle is distorted. The posture tends to be unstable. For this reason, when the post-processing device performs side stitching, the post-processing device counts the number of sheets bundled or the number of sheets discharged to the paper discharge tray instead of detecting that the paper discharge tray has been lowered to the lower limit position. When the counted value reaches a predetermined value, the tray full is detected at an early stage.

  Patent Document 1 below discloses an image forming apparatus that can reliably discharge sheets up to the maximum stacking capacity of a paper discharge tray. In this image forming apparatus, the control unit sets the number of sinking sheets based on the curled index of discharged sheets set based on the sheet type and the number of stacked sheets. The control unit determines that the maximum stacking capacity has been reached in response to determining that the number of discharged sheets is equal to or greater than the number of sinking sheets after determining that the state is the specific state.

JP 2017-030913 A

  The conventional technique has a problem that the generated sheet bundle cannot be stably stacked. The inventor of the present application, when continuously generating a bundle of sheets bound by the post-processing device and stacking and stacking them on the discharge tray, the counted value reaches a predetermined value depending on the curl state of the sheets and the binding position. Before doing so, he found that the stack of sheets would be unstable.

  The problem that the generated sheet bundle cannot be stably stacked is not limited to a post-processing apparatus equipped with a liftable discharge tray, but is a problem common to post-processing apparatuses that generate a sheet bundle. there were.

  SUMMARY An advantage of some aspects of the invention is that it provides a post-processing apparatus and a control method for the post-processing apparatus that can stably stack a generated sheet bundle.

  A post-processing apparatus according to one aspect of the present invention is a binding unit that generates a sheet bundle by binding a plurality of sheets, a discharge unit that discharges a sheet bundle generated by the binding unit, and a discharge unit that discharges the sheet bundle. The stacking means for stacking the sheet bundle, the counting means for counting the number of sheets bundled on the stacking means or the number of sheets constituting the sheet bundle loaded on the stacking means, and the value counted by the counting means is the reference value When the stacking means is full, the fullness determination means for determining that the stacking means is full, the estimated curl state of the sheets constituting the sheet bundle discharged by the discharge means, and the type of binding performed by the binding means And a value setting means for setting a reference value.

  Preferably, in the post-processing apparatus, the value setting unit sets a reference value based on whether the curl state is back curl or face curl, and the back curl is a discharge direction in which the paper is discharged by the discharge unit. Both ends of the paper are curved upward from the central part of the paper in the discharge direction, and the face curl is such that both ends of the paper in the discharge direction for discharging the paper bundle by the discharge means are in the paper in the discharge direction. It is in the state curved to the lower part rather than the center part.

  Preferably, in the post-processing apparatus, the value setting means uses a reference value when the curl state and the binding type are a specific combination, and a reference value when the curl state and the binding type are not a specific combination. Set to a smaller value.

  In the post-processing apparatus, the specific combination preferably includes a combination in which the curl state is back curl and the binding type is two-point binding.

  Preferably, in the post-processing apparatus, the specific combination includes a combination in which the curl state is face curl and the binding type is single-point binding.

  Preferably, in the post-processing apparatus, the binding unit generates a sheet bundle by binding a plurality of printed sheets, and is a printing condition set for printing of the plurality of sheets, the single-sided printing or the double-sided printing. The curling state is estimated based on whether the set printing condition is single-sided printing or double-sided printing and the types of sheets.

  Preferably, in the post-processing apparatus, when the full judging unit judges that the stacking unit is full during printing of a plurality of sheets, it is determined whether to continue printing on a plurality of sheets. And a continuation determination unit determines that printing is to be stopped when the number of sheets that have not been printed or the number of sheets is greater than a predetermined value, and the continuation determination unit determines that printing has been completed. When the number of unstacked sheets or the number of sheets is equal to or less than a predetermined value, it is determined that printing is continued.

  Preferably, in the above-described post-processing apparatus, when the curl state is back curl, the speed at which the sheet bundle is discharged by the discharge unit after the continuous determination unit determines to continue printing is set based on the type of binding. And a speed setting means.

  Preferably, in the post-processing apparatus, when the binding type is one-point binding, the speed setting unit sets the speed at which the sheet bundle is discharged by the discharge unit after the continuation determination unit determines that printing is to be continued. The speed is set to be the same as the speed at which the sheet bundle is discharged by the discharge means before it is determined that printing is continued by the continuation determination means.

  Preferably, in the above-described post-processing apparatus, when the binding type is two-point binding, the speed setting unit determines the speed at which the sheet bundle is discharged by the discharge unit after the continuation determination unit determines to continue printing. The speed is set slower than the speed at which the sheet bundle is discharged by the discharge means before it is determined by the continuation determination means that printing is continued.

  Preferably, in the above-described post-processing apparatus, the stacking unit can be moved up and down, and when the curl state is face curl, the stacking unit after determining that the printing is continued by the continuation determination unit based on the type of binding. Further, position setting means for setting the height position is provided.

  Preferably, in the post-processing apparatus, when the type of binding is one-point binding, the position setting unit uses the continuation determination unit to indicate the height position of the stacking unit after determining that the printing is continued by the continuation determination unit. The height is set higher than the height position of the stacking means before it is determined that the printing is continued.

  Preferably, in the post-processing apparatus, when the binding type is two-point binding, the position setting unit uses the continuation determination unit to indicate the height position of the stacking unit after determining that the printing is continued by the continuation determination unit. The height is set to the same position as that of the stacking means before it is determined that printing is continued.

  Preferably, in the post-processing apparatus, the value setting means sets the reference value when the curl state is back curl and the binding type is two-point binding, the curl state is back curl, and the binding state is The value is set to a value smaller than the reference value when the type is one-point binding.

  Preferably, in the post-processing apparatus, the value setting means sets the reference value when the curl state is face curl and the binding type is one-point binding, and the curl state is face curl and the binding state. The value is set to a value smaller than the reference value when the type is two-point binding.

  A control method of a post-processing apparatus according to another aspect of the present invention includes a binding unit that generates a sheet bundle by binding a plurality of sheets, a discharge unit that discharges a sheet bundle generated by the binding unit, and a discharge unit. A post-processing apparatus having a stacking unit for stacking the discharged sheet bundle, and determining the number of sheets stacked on the stacking unit or the number of sheets constituting the stack of sheets stacked on the stacking unit. A counting step for counting, a fullness determining step for determining that the stacking means is full when the value counted in the counting step reaches a reference value, and an estimated curl state of the sheet bundle discharged by the discharging means And a value setting step for setting a reference value based on the type of binding performed by the binding means.

  ADVANTAGE OF THE INVENTION According to this invention, the control method of the post-processing apparatus which can stack | stack the produced | generated paper bundle stably, and a post-processing apparatus can be provided.

1 is a cross-sectional view schematically showing a configuration of an image forming system in an embodiment of the present invention. 3 is a cross-sectional view schematically showing the configuration of the post-processing device 3. FIG. 3 is a block diagram illustrating a configuration of a control unit 20 of the post-processing device 3. FIG. 5 is a cross-sectional view schematically showing a lowering operation of the paper discharge tray 35. FIG. 3 is a perspective view schematically showing a configuration of a paper discharge tray 35. FIG. FIG. 6 is a diagram for explaining the details of the raising / lowering operation of the discharge tray 35. 4 is a side view schematically showing back curl paper and face curl paper discharged to a paper discharge tray 35. FIG. FIG. 10 is a diagram illustrating evaluation results of a stacking state of a sheet bundle when a predetermined number of sheet bundles are discharged to the discharge tray 35 by a total of four combinations of the curled state of the sheet and the binding type. It is a figure explaining the problem which arises by the combination (combination C2) of a back curl and two places binding. It is a figure explaining the problem which arises with the combination (combination C3) of a face curl and one place binding. It is a figure which shows typically the 1st reference value table in one embodiment of this invention. It is a figure which shows typically the 2nd reference value table in one embodiment of this invention. It is a flowchart which shows the operation | movement regarding determination of the detection method of the tray full which the post-processing apparatus 3 performs in one embodiment of this invention. It is a flowchart which shows the operation | movement at the time of tray full detection which the post-processing apparatus 3 performs when there exists binding in one embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In the following embodiment, an image forming system in which a post-processing apparatus is mounted on an MFP will be described. The post-processing apparatus may be mounted on an image forming apparatus such as a facsimile machine, a copier, or a printer in addition to the MFP, or may be a separate apparatus from the image forming apparatus.

  [Configuration of Image Forming Apparatus]

  FIG. 1 is a cross-sectional view schematically showing a configuration of an image forming system according to an embodiment of the present invention.

  Referring to FIG. 1, the image forming system in the present embodiment includes document reading device 1, image forming device 2, and post-processing device 3. The document reading apparatus 1 is provided on the upper part of the image forming apparatus 2. The post-processing device 3 is provided on the left side of the image forming apparatus in FIG.

  The document reading device 1 sequentially reads a document set on a document table, generates image data of the document, and transmits the generated image data to the image forming device 2.

  The image forming apparatus 2 performs printing on a sheet by an electrophotographic method. The image forming apparatus 2 transfers the image to a sheet, fixes the transferred image on the sheet, and conveys the image to the post-processing apparatus 3. The image forming apparatus 2 includes an operation panel 2a. The operation panel 2a accepts various operations and displays various information.

  The post-processing device 3 performs various post-processing (perforation processing, folding processing, binding processing, or the like) on paper printed by the image forming apparatus 2 or manual paper (paper not printed by the image forming apparatus 2). )I do.

  FIG. 2 is a cross-sectional view schematically showing the configuration of the post-processing apparatus 3.

  Referring to FIG. 2, the post-processing device 3 includes a control unit 20, a transport unit 31, a saddle unit 32, a stapler unit 33 (an example of a binding unit), and an alignment / discharge unit 34 (an example of a discharge unit). And paper discharge trays 35 and 36 and a horizontal transport unit 37.

  The control unit 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 20 controls the entire post-processing device 3 by the CPU executing a control program stored in the ROM.

  The transport unit 31 transports the paper transported from the horizontal transport unit 37 into the post-processing device 3. The transport unit 31 performs a paper punching process using a punching device as necessary. The transport unit 31 performs a Z-folding process on the paper by a Z-folding device as necessary. Further, the transport unit 31 switches the path of the paper transported to the paper discharge tray 35 or 36.

  The saddle unit 32 performs saddle stitching, center folding, or tri-folding on the sheet, and discharges the sheet to the sheet discharge tray 32a.

  The stapler unit 33 generates a sheet bundle by binding a plurality of sheets with one-point binding or two-point binding. Here, it is assumed that the stapler unit 33 performs side stitching. Hereinafter, the operation of the stapler unit 33 may be referred to as a binding process. The stapler unit 33 conveys the generated sheet bundle to the alignment / discharge unit 34.

  The alignment / discharge unit 34 aligns a plurality of sheets in the vertical direction and the horizontal direction. The alignment / discharge unit 34 performs an operation of shifting the paper in the width direction of the paper as necessary. The alignment / discharge unit 34 discharges the conveyed sheet or sheet bundle to the sheet discharge tray 35 through the discharge port 3b.

  The paper discharge trays 35 and 36 stack sheets discharged from the discharge ports 3b and 3a of the post-processing device 3, respectively. The paper discharge tray 35 (an example of a stacking unit) is a main tray, and the paper discharge tray 36 is a sub-tray. In particular, the paper discharge tray 35 stacks sheets that have been subjected to post-processing such as Z-folding and stacks sheets that have undergone binding processing.

  The horizontal conveyance unit 37 conveys the printed paper discharged from the image forming apparatus 2 to the conveyance unit 31.

  FIG. 3 is a block diagram illustrating a configuration of the control unit 20 of the post-processing device 3.

  Referring to FIG. 3, the control unit 20 includes a post-processing control unit 21, a communication unit 22 (an example of a printing condition acquisition unit), a counting unit 23 (an example of a counting unit), and a tray full detection unit 24 (a fullness determination). And an continuation determination unit 25 (an example of a continuation determination unit), and a paper discharge condition change unit 26 (an example of a speed setting unit and a position setting unit).

  The post-processing control unit 21 controls the operation of each member of the post-processing device 3.

  The communication unit 22 communicates with the image forming apparatus 2.

  The count unit 23 counts the number of sheets stacked on the sheet discharge tray 35 or the number of sheets constituting the sheet bundle stacked on the sheet discharge tray 35. The counting unit 23 estimates the number of sheet bundles stacked on the discharge tray 35 or the number of sheets constituting the sheet bundle stacked on the discharge tray 35 based on the height position of the discharge tray 35. Count the estimated value. The counting unit 23 counts the number of sheets printed in the image forming apparatus 2 as the number of sheets stacked on the sheet discharge tray 35 or the number of sheets constituting the sheet bundle stacked on the sheet discharge tray 35. May be.

  The tray full detection unit 24 detects each tray full of the paper discharge trays 32a, 35, and 36.

  The continuation determination unit 25 determines whether or not to continue printing of the sheet or the sheet bundle when the tray full of the sheet discharge tray 35 is detected.

  The paper discharge condition changing unit 26 changes the paper discharge conditions when the tray full detection unit 24 detects that the tray is full.

  [Output Tray Configuration and Lifting Operation]

  FIG. 4 is a cross-sectional view schematically showing the lowering operation of the paper discharge tray 35.

  Referring to FIG. 4, in order to keep the distance between the top surface of the sheet or sheet bundle discharged to the sheet discharge tray 35 and the discharge port 3 b constant and to eliminate the unevenness of the stacked sheets or sheet bundle, Can be moved up and down. The post-processing control unit 21 rotationally drives the main tray driving belt 38 with the power of a main tray lifting / lowering motor (not shown). The paper discharge tray 35 is raised and lowered by interlocking with the main tray drive belt 38. The movable range of the discharge tray 35 is from the home position (upper limit position) PO1 to the tray full position (lower limit position) PO2 or PO3.

  When a sheet or sheet bundle is discharged from the discharge port 3b to the discharge tray 35, the discharge tray 35 is lowered in the direction of the arrow and stopped at a position that satisfies a predetermined condition. A method for determining the stop position of the discharge tray 35 will be described later with reference to FIG. The paper discharge tray 35 is lowered as the number of sheets or paper bundles stacked increases.

  The tray full positions (lower limit positions) PO2 and PO3 are positions of the paper discharge tray 35 when the paper discharge tray 35 becomes full. The tray full position PO2 is a tray full position when the saddle portion 32 and the paper discharge tray 32a are mounted on the post-processing device 3. The tray full position PO3 is a tray full position when the saddle portion 32 and the paper discharge tray 32a are not mounted on the post-processing device 3. When the saddle portion 32 and the paper discharge tray 32a are not mounted on the post-processing device 3, the corresponding space is left in the post-processing device 3, so that the tray full position of the paper discharge tray 35 can be set further downward. .

  Main tray full sensors 39 a and 39 b are provided on the side surface of the main body of the post-processing device 3. The main tray full sensor 39a detects the paper discharge tray 35 at the tray full position PO2. The main tray full sensor 39b detects the paper discharge tray 35 at the tray full position PO3.

  FIG. 5 is a perspective view schematically showing the configuration of the paper discharge tray 35.

  Referring to FIG. 5, the paper discharge tray 35 includes a placement unit 41, a paper detection sensor (main tray paper detection sensor) 42, a paper pressing motor 43, and two lowering detection sensors (main tray lowering detection sensor). 44, two rise detection sensors (main tray rise detection sensors) 45, a sheet pressing sensor 46, and two sheet surface detection levers 47.

  The placement portion 41 is provided on the upper surface of the paper discharge tray 35. The sheet detection sensor 42, the sheet pressing motor 43, the two lowering detection sensors 44, the two lifting detection sensors 45, and the sheet pressing sensor 46 are provided on the side surface of the sheet discharge tray 35 facing the main body of the post-processing device 3. ing. The two paper surface detection levers 47 are fixed at predetermined positions in the main body of the post-processing device 3. In particular, each of the descending detection sensor 44, the ascending detection sensor 45, and the paper surface detection lever 47 is provided in the vicinity of both end portions in the horizontal direction in FIG.

  The placement unit 41 is a portion on which a sheet or a bundle of sheets is stacked.

  The sheet detection sensor 42 detects the presence or absence of a sheet or sheet bundle placed on the placement unit 41.

  The paper pressing motor 43 drives the paper surface detection lever 47.

  The lowering detection sensor 44 instructs the post-processing control unit 21 to lower the discharge tray 35 according to the detection result of the paper surface detection lever 47.

  The rise detection sensor 45 instructs the post-processing control unit 21 to raise the discharge tray 35 according to the detection result of the paper surface detection lever 47.

  The paper press sensor 46 detects the home position of the paper surface detection lever 47.

  The paper surface detection lever 47 rotates so as to come into contact with the upper surface of the paper or paper bundle placed on the placement portion 41.

  FIG. 6 is a diagram for explaining the details of the raising / lowering operation of the paper discharge tray 35.

  Referring to FIG. 6A, the post-processing control unit 21 uses the lowering detection sensor 44, the rising detection sensor 45, and the paper surface detection lever 47 to detect the upper surface of the paper or the paper bundle stacked on the paper discharge tray 35. And the outlet 3b are kept constant. Thereby, unevenness of discharged sheets or sheet bundles is prevented.

  Under the control of the post-processing control unit 21, the paper surface detection lever 47 can be rotated about the main body 471 as indicated by an arrow AR1. The paper surface detection lever 47 includes a main body portion 471, a lever 472, a lowering detection plate 474, and a rising detection plate 475. The lever 472 is a portion that comes into contact with the upper surface of the paper or paper bundle placed on the placement portion 41 and protrudes from the main body portion 471 in one direction. The lowered detection plate 474 and the rising detection plate 475 protrude from the main body 471 at a position substantially opposite to the lever 472. The detection plate 474 for lowering is slightly shifted to the downstream side in the rotation direction of the main body 471 with respect to the detection plate 475 for raising. The descending detection plate 474 passes the detection position 44a of the descending detection sensor 44 when the paper surface detection lever 47 is in a predetermined rotation range. The detected plate 475 for rising passes the detection position 45a of the rising detection sensor 45 when the paper surface detection lever 47 is in a predetermined rotation range.

  The lowering detection sensor 44 detects the lowering detection plate 474 at the detection position 44 a and outputs the detection result to the post-processing control unit 21. The rising detection sensor 45 detects the rising detection plate 475 at the detection position 45 a and outputs the detection result to the post-processing control unit 21.

  Here, it is assumed that the paper SH is discharged to the paper discharge tray 35. When no paper is placed on the paper discharge tray 35 or when a new paper is discharged to the paper discharge tray 35, the paper surface detection lever 47 stands by at the home position shown in FIG. The home position of the paper surface detection lever 47 is a state where the lever 472 is erected in a substantially vertical direction. The paper surface detection lever 47 is not interlocked with the raising / lowering operation of the paper discharge tray 35.

  Referring to FIG. 6B, when the paper SH is discharged to the paper discharge tray 35, the paper surface detection lever 47 rotates counterclockwise as shown by the arrow AR1a and is discharged to the paper discharge tray 35. Stop at a position in contact with the upper surface of the sheet SH. Along with the rotation of the paper surface detection lever 47, the detection plate for lowering 474 and the detection plate for lifting 475 also rotate counterclockwise.

  Referring to FIG. 6C, when the distance between the upper surface of the paper SH stacked on the paper discharge tray 35 and the discharge port 3b is too close, the rotation distance of the lever 472 from the home position becomes short. As a result, the lower detection plate 474 is present at the detection position 44a of the lower detection sensor 44, and the upper detection plate 475 is not present at the detection position 45a of the rise detection sensor 45, and the lower detection sensor 44 is turned on. The rise detection sensor 45 is turned off. In this case, the post-processing control unit 21 lowers the discharge tray 35 as indicated by an arrow AR2a until both the lowering detection sensor 44 and the rising detection sensor 45 are turned on.

  The position of the paper discharge tray 35 where both the lowering detection sensor 44 and the upward detection sensor 45 are in the ON state is such that the distance between the upper surface of the paper or paper bundle stacked on the paper discharge tray 35 and the discharge port 3b is correct. It corresponds to the position.

  Referring to FIG. 6D, when the distance between the upper surface of the paper SH stacked on the paper discharge tray 35 and the discharge port 3b is too far, the rotation distance of the lever 472 from the home position becomes long. As a result, the detection plate 474 for lowering does not exist at the detection position 44a of the lowering detection sensor 44, and the detection plate 475 for increase is present at the detection position 45a of the upward detection sensor 45, and the lowering detection sensor 44 is turned off. The rise detection sensor 45 is turned on. In this case, the post-processing control unit 21 raises the discharge tray 35 as indicated by the arrow AR2b until both the lowering detection sensor 44 and the rising detection sensor 45 are turned on.

  The paper surface detection lever 47 repeats the above operation every time a new paper SH is discharged to the paper discharge tray 35, and returns to the home position after the job is completed. Even if the paper SH stacked on the paper discharge tray 35 is removed, the paper discharge tray 35 does not move until the next post-processing job is started.

  [Relationship between the curl state and binding position of the paper and the stability of the paper bundle loaded on the paper output tray]

  FIG. 7 is a side view schematically showing the back curl sheet and the face curl sheet discharged to the sheet discharge tray 35. FIG. 7A shows the back curl paper discharged to the paper discharge tray 35, and FIG. 7B shows the face curl paper.

  Referring to FIG. 7, the paper is curled (curved) during printing due to heat and pressure received when the paper passes through the fixing device of image forming apparatus 2. Various types of paper are used in the market, and the degree of curling that occurs during printing differs depending on the type of paper. The types of paper curl include back curl and face curl.

  Referring to FIG. 7A, in the back curl, both end portions eg of the sheet bundle in the discharge direction (direction indicated by arrow AR3) in which the sheet SH is discharged by the alignment / discharge unit 34 are formed on the sheet SH in the discharge direction. It is in a state of being curved upward from the center part ct. Back curl is likely to occur when the paper is of a specific type and when single-sided printing is performed on the paper (when the paper passes through the fixing device once).

  Referring to FIG. 7B, the face curl is a state in which both end portions eg of the paper in the discharge direction are curved below the center portion ct of the paper in the discharge direction. Face curl is likely to occur when the paper is of a specific type and when duplex printing is performed on the paper (when the paper passes through the fixing device twice).

  Hereinafter, the type of paper that easily curls (back curl or face curl) may be referred to as type B, and the type of paper that is difficult to curl may be referred to as type A.

  Since the sheet bundle is bound by the needle, when the bound sheet bundle is continuously discharged to the discharge tray 35, the sheet bundle is locally swollen by the staple at the binding position, and the stacked sheet bundle is easily distorted. Become. In particular, when a sheet bundle composed of type B paper that is easily curled is continuously discharged to the paper discharge tray 35, a sheet bundle composed of type A paper that is difficult to curl is placed on the paper discharge tray 35. Compared with the case of continuous discharge, the stack of stacked sheets becomes more distorted.

  FIG. 8 is a diagram showing the evaluation result of the stacking state of the sheet bundle when a predetermined number of sheet bundles are discharged to the discharge tray 35 by a total of four combinations of the paper curl state and the binding type. It is.

  Referring to FIG. 8, the inventor of the present application compares the state of curl of the paper constituting the two bundles of paper, that is, back curl and face curl, and two types of binding, that is, one-point binding and two-point binding. With a total of four combinations, a predetermined number of paper bundles were discharged to the paper discharge tray 35, and the stacking state of the paper bundles on the paper discharge tray 35 was evaluated. The back curl was realized by printing on one side of the paper, and the face curl was realized by printing on both sides of the paper.

  As a result, in each of the combination of back curl and two-point binding (combination C2) and the combination of face curl and single-point binding (combination C3), the sheet bundle stacked on the paper discharge tray 35 becomes unstable. There was a problem. In each of the combination of back curl and one-point binding (combination C1) and the combination of face curl and two-point binding (combination C4), there arises a problem that the sheet bundle stacked on the paper discharge tray 35 becomes unstable. There wasn't.

  FIG. 9 is a diagram for explaining a problem caused by a combination of the back curl and the two-point binding (combination C2). FIG. 10 is a diagram for explaining a problem caused by a combination of face curl and one-point binding (combination C3). In FIGS. 9 and 10, the binding position in the sheet bundle is indicated by a cross. Here, in the case of single-point binding, one end in the paper width direction (the direction indicated by the arrow AR4, the direction perpendicular to the discharge direction) is the binding position on the upstream side in the paper discharge direction. . In the case of two-point binding, the two ends in the discharge direction upstream end of the sheet and different in the direction orthogonal to the discharge direction are the binding positions.

  Referring to FIG. 9, in the combination of the back curl and the two-point binding (combination C2), the paper stacked on the paper discharge tray 35 before the predetermined number of paper bundles are discharged to the paper discharge tray 35. There was a phenomenon in which the sheet bundle near the top surface of the bundle BS was pushed out in the discharge direction (direction indicated by the arrow AR3). There was also a phenomenon in which the pushed sheet bundle dropped from the sheet discharge tray 35.

  When the sheet bundle BS stacked on the sheet discharge tray 35 is back-curled, the sheet bundle BS is in a posture where the vicinity of the central portion in the discharge direction is recessed as shown in FIG. On the other hand, since the sheet bundle BS1 that is newly discharged to the sheet discharge tray 35 is also back-curled, when the new sheet bundle BS1 is discharged, the leading end (the end on the downstream side in the discharge direction) of the sheet bundle BS1 is Then, it contacts a region RG1 in the vicinity of the downstream end portion in the discharge direction on the uppermost surface of the sheet bundle BS.

  When the binding type of the sheet bundle is two-point binding, there is no difference in height in the sheet width direction on the top surface of the stacked sheet bundle BS. For this reason, the entire front end of the sheet bundle BS1 comes into contact with the uppermost surface of the sheet bundle BS, and a large impact is transmitted to the uppermost surface of the sheet bundle BS. By this impact, as shown in FIG. 9B, the sheet bundle BS2 near the uppermost surface of the sheet bundle BS is pushed out together with the sheet bundle BS1 in the discharge direction. As a result, the sheet bundle stacked on the paper discharge tray 35 becomes unstable.

  Referring to FIG. 10, in the combination of face curl and one-point binding (combination C3), before a predetermined number of sheet bundles are discharged to discharge tray 35, they are newly discharged to discharge tray 35. The leading edge EG of the sheet bundle BS1 is rounded as indicated by an arrow AR5, and a phenomenon in which a stacking failure occurs is observed.

  In the case of a sheet bundle BS that is face-curled, the sheet bundle BS stacked on the sheet discharge tray 35 is, as shown in FIG. 10A, at the upstream end in the discharge direction (the direction indicated by the arrow AR3). A height difference in the paper width direction occurs. That is, the end on the bound side in the paper width direction (the direction indicated by the arrow AR4) is increased, and the end opposite to the bound side is decreased. This difference in height increases as the number of sheet bundles BS stacked on the paper discharge tray 35 increases.

  On the other hand, since the sheet bundle BS1 newly discharged to the sheet discharge tray 35 is face-curled, when the sheet bundle BS1 is discharged, the leading end of the sheet bundle BS1 (the end on the downstream side in the discharge direction) is It hangs down as shown in 10 (b). In particular, the front end portion EG opposite to the bound side in the paper width direction drastically drops compared to the front end portion on the bound side in the paper width direction, and the sheet bundle BS stacked on the front end portion EG and the paper discharge tray 35. The angle θ formed with the uppermost surface of is increased. As a result, the leading edge EG is rounded as indicated by an arrow AR5, and the sheet bundle BS1 is stacked in a folded state, resulting in a stacking failure. As a result, the sheet bundle stacked on the paper discharge tray 35 becomes unstable.

  [Tray full detection method of paper discharge tray 35]

  Next, a tray full detection method for the paper discharge tray 35 performed by the tray full detection unit 24 in the present embodiment will be described.

  With reference to FIGS. 1 to 4, the tray full detection unit 24 acquires the set printing condition and post-processing condition from the image forming apparatus 2 through the communication unit 22. Based on the acquired information, the tray full detection unit 24 determines whether the sheet or sheet bundle discharged to the sheet discharge tray 35 is “unbound sheet” or “bound sheet bundle”. The tray full of the paper discharge tray 35 is detected by a different detection method in each case.

  (1) When the paper or paper bundle discharged to the paper output tray 35 is “paper that has not been bound”

  In this case, the tray full detection unit 24 detects the tray full of the paper discharge tray 35 based on the detection result of the main tray full sensor 39a or 39b. The tray full detection unit 24 detects the tray full of the paper discharge tray 35 when the paper discharge tray 35 descends to the tray full position and the main tray full sensor 39a or 39b detects the paper discharge tray 35.

  (2) When the paper or paper bundle discharged to the paper output tray 35 is a “bound paper bundle”

  When the bound sheet bundle is continuously stacked on the sheet discharge tray 35, the local bulge of the sheet bundle due to overlapping needles is accumulated, and the posture of the sheet bundle stacked on the sheet discharge tray 35 is distorted. It becomes easy to do. As a result, the stack of sheets stacked on the discharge tray 35 is likely to become unstable.

  In this case, the tray full detection unit 24 is based on the value counted by the counting unit 23 (the number of sheets stacked on the discharge tray 35 or the number of sheets constituting the sheet stack stacked on the discharge tray 35). The tray full of the paper discharge tray 35 is detected. When the value counted by the counting unit 23 reaches the reference value, the tray full detection unit 24 detects the tray full of the paper discharge tray 35 even if the paper discharge tray 35 is not lowered to the tray full position.

  The tray full detection unit 24 uses a standard for detecting the tray full based on the estimated curl state of the sheets constituting the bound sheet bundle and the type of binding performed by the stapler unit 33 on the sheet bundle. Set the value. The curl state is estimated based on whether the printing condition set for printing of the sheets constituting the sheet bundle is single-sided printing or double-sided printing, and the types of sheets constituting the sheet bundle. The printing conditions are acquired from the image forming apparatus 2 through the communication unit 22.

  (2-a) When the type of paper constituting the paper bundle is type A

  The tray full detection unit 24 estimates that the paper constituting the bound paper bundle is not curled when the type of paper constituting the paper bundle is the type A that is difficult to curl. In this case, the tray full detection unit 24 sets a reference value for tray full detection by referring to the first reference value table regardless of the type of binding performed by the stapler unit 33 on the sheet bundle.

  FIG. 11 is a diagram schematically showing a first reference value table in one embodiment of the present invention.

  Referring to FIG. 11, the first reference value table is stored in the ROM or the like of control unit 20. The first reference value table describes the relationship between the number of sheets constituting one sheet bundle discharged to the discharge tray 35 and the number of sheet bundles serving as a reference value for tray full detection. In the first reference value table, as the number of sheets constituting one sheet bundle discharged to the discharge tray 35 increases, the number of sheet bundles serving as a reference value for tray full detection decreases. In this embodiment, (the number of sheets constituting the sheet bundle) × (the number of sheet bundles) is set to be within 1000 sheets.

  Specifically, when the number of sheets constituting one sheet bundle is 2 to 5, the number of sheet bundles serving as a reference value for tray full detection is 200 copies, and is 6 to 10 sheets. 100 copies in the case, 50 copies in the case of 11 to 20 copies, 30 copies in the case of 21 to 30 copies, and 25 copies in the case of 31 to 40 copies. In the case of 41 to 50 sheets, it is 20 copies.

  (2-b) When the paper type constituting the paper bundle is type B

  When the type of paper constituting the paper bundle is a type B that tends to curl, the tray full detection unit 24 sets either one-sided printing or double-sided printing as the printing condition set for printing the paper constituting the paper bundle. Based on the above, it is estimated whether the curl state of the sheets constituting the sheet bundle is the back curl or the face curl. The tray full detection unit 24 sets a reference value for tray full detection by referring to the second reference value table.

  FIG. 12 is a diagram schematically showing a second reference value table in one embodiment of the present invention.

  Referring to FIG. 12, the second reference value table is stored in the ROM or the like of control unit 20. The second reference value table describes the relationship between the number of sheets constituting the sheet bundle discharged to the discharge tray 35 and the number of sheet bundles serving as a reference value for tray full detection.

  This relationship differs depending on the combination of the paper curl state and the binding type. When compared with the reference value of tray full detection when the number of sheets constituting one sheet bundle belongs to the same range (for example, 2 to 5 sheets), the combination of back curl and one-point binding (combination C1) The reference value for tray full detection in a certain case, and the reference value for tray full detection in the case of a combination of face curl and two-point binding (combination C4) are the cases where the paper constituting the paper bundle is not curled (first This is the same as the reference value for tray full detection in the reference value table. This is because the combination of back curl and one-point binding (combination C1) and the combination of face curl and two-point binding (combination C4) can stably stack the sheet bundle.

  On the other hand, the reference value for tray full detection in the case of a combination of back curl and two-point binding (combination C2), and the reference value for tray full detection in the case of a combination of face curl and single-point binding (combination C3) are: The value is smaller than the reference value for tray full detection when the sheets constituting the sheet bundle are not curled (in the case of the first reference value table).

  That is, in the second reference table, in the case of a combination of back curl and two-point binding (combination C2), a sheet bundle near the top surface is pushed out of the sheet bundle stacked on the discharge tray 35. Compared with the case where the paper constituting the paper bundle is not curled (in the case of the first reference value table) in order to suppress the phenomenon that the pushed paper bundle falls from the paper discharge tray 35 (FIG. 9). The tray full of the paper discharge tray 35 is detected at an early timing. Further, in the case of the combination of face curl and one-point binding (combination C3), the leading end of the sheet bundle that is newly discharged to the discharge tray 35 is rounded, and a phenomenon in which a stacking defect occurs (FIG. 10) is suppressed. Therefore, the tray full of the paper discharge tray 35 is detected at an earlier timing than when the sheets constituting the sheet bundle are not curled (in the case of the first reference value table).

  [Operation when tray full is detected]

  Referring to FIGS. 1 to 3, when the sheet or sheet bundle discharged to sheet discharge tray 35 is “sheet not subjected to binding processing” (case (1) above), printing of the sheet or sheet bundle is performed. When the tray full detection unit 24 detects that the paper discharge tray 35 is full, the control unit 20 stops the printing operation relating to the paper discharged to the paper discharge tray 35 by the communication unit 22 and warns that the tray is full. Is displayed to the image forming apparatus 2.

  In response to these requests, the image forming apparatus 2 stops the printing operation relating to the paper discharged to the paper discharge tray 35, and displays a warning that the tray is full on the operation panel 2a.

  When the sheet or sheet bundle discharged to the sheet discharge tray 35 is a “bound bundle of sheets” (in the case of (2) above), the tray full detection unit 24 ejects the sheet constituting the sheet bundle during printing. When the tray full of the paper tray 35 is detected, the continuation determination unit 25 determines whether or not to continue printing on paper that has not been printed. The continuation determination unit 25 determines this based on whether or not the number of sheets that have not been printed or the number of sheets is greater than a predetermined value.

  Specifically, the continuation determination unit 25 determines to stop printing when the number of sheets that have not been printed or the number of sheets is greater than a predetermined value. In this case, the continuation determination unit 25 requests the image forming apparatus 2 to stop the printing operation related to the paper discharged to the paper discharge tray 35 by the communication unit 22 and to display a warning that the tray is full.

  In response to these requests, the image forming apparatus 2 stops the printing operation relating to the paper discharged to the paper discharge tray 35, and displays a warning that the tray is full on the operation panel 2a.

  The continuation determination unit 25 determines to continue printing when the number of sheets that have not been printed or the number of sheets is equal to or less than a predetermined value. In this case, the continuation determination unit 25 requests the image forming apparatus 2 to display a warning that the tray is full after printing is completed.

  Upon completion of printing, the image forming apparatus 2 receives this request and displays a warning that the tray is full on the operation panel 2a.

  Note that the image forming apparatus 2 may not accept a new print job when a warning is displayed.

  The operability of the post-processing device 3 can be improved by continuing printing when the number of sheets that have not been printed or the number of sheets is equal to or less than a predetermined value. In other words, when printing is stopped due to the tray full after a short time, the user removes the sheet bundle stacked on the paper discharge tray 35 and resumes the tray full in order to resume printing. Is required. Such a work can be avoided by continuing the printing when the number of sheets that have not been printed or the number of sheets is equal to or less than a predetermined value.

  Referring to FIG. 2, when it is determined that printing is to be continued, the following control is performed in order to reduce the factor that causes the sheet bundle stacked on the discharge tray 35 to become unstable.

  If it is determined that printing is to be continued and the curl state of the sheets constituting the sheet bundle is estimated to be back curl, the paper discharge condition changing unit 26 continues printing based on the type of binding. The speed at which the sheet bundle is discharged by the alignment / discharge unit 34 after the determination is set.

  That is, when the combination of the curl state of the sheets constituting the sheet bundle and the binding type is a combination of back curl and two-point binding (combination C2), the paper discharge condition changing unit 26 performs post-processing control. The speed at which the alignment / discharge unit 34 discharges the sheet bundle after determining that printing is continued by the unit 21 is slower than the speed at which the alignment / discharge unit 34 discharges the sheet bundle before determining that printing is to be continued. (For example, 50% to 80% of the speed at which the alignment / discharge unit 34 discharges the sheet bundle before it is determined to continue printing). On the other hand, when it is determined that printing is to be continued, if the combination of the curl state and the binding type of the sheets constituting the sheet bundle is a combination of back curl and one-point binding (combination C1), the sheet is discharged. The condition changing unit 26 sets the speed of discharging the sheet bundle by the aligning / discharging unit 34 to the same speed as the speed of discharging the sheet bundle by the aligning / discharging unit 34 before determining to continue printing.

  When the combination of the curl state of the sheets constituting the sheet bundle and the binding type is a combination of back curl and two-point binding (combination C2), the sheet discharge is performed by slowing the discharge speed of the sheet bundle. The impact (FIG. 9) that the sheet bundle loaded on the tray 35 receives from the newly ejected sheet bundle can be reduced, and the sheet bundle can be stably loaded even after the tray full is detected.

  If it is determined that printing is to be continued and the curl state of the sheets constituting the sheet bundle is estimated to be face curl, the paper discharge condition changing unit 26 continues printing based on the binding type. After the determination, the height position of the paper discharge tray 35 is set.

  That is, when the combination of the curl state of the sheets constituting the sheet bundle and the binding type is a combination of face curl and one-point binding (combination C3), the paper discharge condition changing unit 26 performs post-processing control. The unit 21 sets the height position of the paper discharge tray 35 after it is determined to continue printing to a position higher than the height position of the paper discharge tray 35 before it is determined to continue printing by a predetermined amount (see FIG. The sheet discharge tray 35 is raised by a predetermined amount from the height position of the sheet discharge tray 35 determined by the method shown in FIG. On the other hand, when the combination of the curl state and the binding type of the sheets constituting the sheet bundle is a combination of face curl and two-point binding (combination C4), the discharge condition changing unit 26 continues printing. Then, the height position of the paper discharge tray 35 after the determination is made is set to the same position as the height position of the paper discharge tray 35 before it is determined to continue printing.

  When the combination of the curl state of the sheets constituting the sheet bundle and the binding type is a combination of face curl and one-point binding (combination C3), the sheet discharge tray 35 is set to a high position to set a new position. The angle θ (FIG. 10) formed by the leading edge of the sheet bundle discharged to the paper discharge tray 35 and the top surface of the sheet bundle loaded on the discharge tray 35 can be reduced, and the sheet bundle can be stably stacked even after the tray full is detected. can do.

  [flowchart]

  FIG. 13 is a flowchart showing an operation related to determination of a tray full detection method performed by the post-processing device 3 according to the embodiment of the present invention.

  Referring to FIG. 13, the control unit 20 determines whether or not a print start notification is received from the image forming apparatus 2 (S1). The control unit 20 repeats the process of step S <b> 1 until it is determined that a print start notification is received from the image forming apparatus 2.

  If it is determined in step S3 that a print start notification has been received from the image forming apparatus 2 (YES in S1), the control unit 20 acquires information on printing conditions and post-processing conditions from the image forming apparatus 2 (S3). . The information acquired in step S3 includes, for example, the paper type (type A or type B), the printing conditions (single-sided printing or double-sided printing), the binding type (no binding, one-point binding, or two-point binding), and Includes a stack or number of sheets.

  Subsequent to step S3, the control unit 20 determines whether or not the set binding type is bindingless (S5).

  If it is determined in step S5 that the set binding type is “no binding” (YES in S5), the control unit 20 determines that the sheet or sheet bundle discharged to the discharge tray 35 is “sheet not subjected to binding processing”. ”, The tray full of the paper discharge tray 35 is detected based on the detection result of the main tray full sensor 39a or 39b (S7), and the process ends.

  If it is determined in step S5 that the set binding type is not binding (NO in S5), the control unit 20 determines whether the set paper type is type A (S9).

  If it is determined in step S9 that the set paper type is type A (YES in S9), the control unit 20 estimates that the paper constituting the bound paper bundle is not curled. The control unit 20 detects the tray full using the reference value set using the first reference value table (S11), and ends the process.

  If it is determined in step S9 that the set paper type is not type A (YES in S9), the control unit 20 estimates that the paper constituting the bound paper bundle is curled. The control unit 20 detects the tray full using the reference value set using the second reference value table (S13), and ends the process.

  FIG. 14 is a flowchart illustrating an operation at the time of tray full detection performed by the post-processing device 3 when binding is present in the embodiment of the present invention.

  Referring to FIG. 14, the control unit 20 determines whether or not the tray full of the paper discharge tray 35 is detected during the printing of the sheet to be bound (S21). The control unit 20 repeats the process of step S21 until it is determined that the tray full of the paper discharge tray 35 is detected during the printing of the paper to be bound.

  In step S21, when it is determined that the tray full of the paper discharge tray 35 is detected during printing of the sheets to be bound (YES in S21), the control unit 20 forms the remaining number of sheets m until the printing is completed. Obtained from the device 2 (S23). Next, the control unit 20 determines whether or not the remaining sheet bundle number m is larger than the predetermined number M (S25).

  When it is determined in step S25 that the remaining number of sheets m is larger than the predetermined number M (YES in S25), the control unit 20 displays a warning indicating that the printing operation is stopped and that the tray is full. 2 is requested (S39), and the process is terminated.

  If it is determined in step S25 that the remaining number of sheets m is smaller than the predetermined number M (NO in S25), the control unit 20 determines whether or not the sheet type is type B (S27).

  If it is determined in step S27 that the paper type is not type B (NO in S27), the control unit 20 proceeds to the process of step S37.

  If it is determined in step S27 that the paper type is type B (YES in S27), the control unit 20 determines that the combination of printing conditions and binding type is a combination of single-sided printing (back curl) and two-point binding. It is determined whether or not (S29).

  If it is determined in step S29 that the combination of the printing condition and the binding type is a combination of single-sided printing (back curl) and two-point binding (YES in S29), the control unit 20 uses the alignment / discharge unit 34. The speed at which the sheet bundle is discharged is changed from the speed V0 to the speed V1 (<V0) (S31), and the process proceeds to step S37.

  If it is determined in step S29 that the combination of the printing condition and the binding type is not a combination of single-sided printing (back curl) and two-point binding (NO in S29), the control unit 20 determines the printing condition and the binding type. It is determined whether or not the combination is a combination of double-sided printing (face curl) and one-point binding (S33).

  In step S33, when it is determined that the combination of the printing condition and the binding type is a combination of double-sided printing (face curl) and single-point binding (YES in S33), the control unit 20 determines the height of the discharge tray 35. The position is set to a position that is higher by a predetermined amount Xmm (X is an arbitrary positive number) than the height position of the paper discharge tray 35 at the normal time (S35), and the process proceeds to step S37.

  If it is determined in step S33 that the combination of the printing condition and the binding type is not a combination of double-sided printing (face curl) and single-point binding (NO in S33), the control unit 20 proceeds to the process of step S37.

  In step S37, the control unit 20 determines whether printing is completed (S37). The control unit 20 repeats the process of step S37 until it is determined that printing is complete.

  If it is determined in step S37 that printing has been completed (YES in S37), the control unit 20 requests the image forming apparatus 2 to stop the printing operation and display a warning indicating that the tray is full (S39). The process is terminated.

  [Effect of the embodiment]

  According to the above-described embodiment, when the post-processing device continuously generates the bound sheet bundle and stacks it on the paper discharge tray, the estimated curl state and the binding state of the sheets constituting the generated sheet bundle are bound. The reference value for determining the tray full is set based on the type of the tray. This causes problems caused by the curl state of the paper and the type of binding (the phenomenon that the paper bundle near the top surface of the paper bundle loaded on the paper output tray is pushed out in the discharge direction, The phenomenon of falling from the paper output tray and the phenomenon that the leading edge of the new paper bundle that is newly discharged to the paper output tray is rounded to prevent a stacking failure can be prevented in advance, and the generated paper bundle can be stably stacked. be able to.

  In addition, even if it is determined that the tray is full, printing is continued in a predetermined case, so that the stop of printing due to the tray full can be reduced, and operability can be improved. Further, when printing is continued, control is performed so as to reduce the factor that causes the sheet bundle stacked on the paper discharge tray to become unstable, so that the generated sheet bundle can be stably stacked.

  [Others]

  The paper types may be classified into three or more types according to the size of curl generated during printing, and different reference value tables may be provided for each type.

  When different reference value tables are used depending on the type of paper, the number of paper sheets constituting the paper bundle or the number of paper bundles may be different from each other in each reference value table.

  Different reference values for tray full detection may be set according to the binding type (one-point binding or two-point binding).

  Further, instead of estimating the curl state of the sheets constituting the sheet bundle based on the paper type and the printing conditions, an input of the curl state of the sheet may be received from the user through an operation panel or the like.

  The processing in the above-described embodiment may be performed by software or by using a hardware circuit. It is also possible to provide a program for executing the processes in the above-described embodiments and modifications, and record the program on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card. It may be provided to the user. The program is executed by a computer such as a CPU. The program may be downloaded to the apparatus via a communication line such as the Internet.

  The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Document reading apparatus 2 Image forming apparatus 2a Operation panel 3 Post-processing apparatus 3a, 3b Discharge port of post-processing apparatus 20 Control part 21 Post-processing control part 22 Communication part (an example of printing condition acquisition means)
23 Counting part (an example of counting means)
24 Tray full detection unit (an example of full determination means and value setting means)
25 Continuation judgment part (an example of continuation judgment means)
26 Paper discharge condition changing section (an example of speed setting means and position setting means)
31 Conveying section 32 Saddle section 32a, 35, 36 Paper discharge tray (an example of stacking means)
33 Stapler (an example of binding means)
34 Alignment / discharge section (an example of discharge means)
37 Horizontal transport section 38 Main tray drive belt 39a, 39b Main tray full sensor 41 Placement section 42 Paper detection sensor 43 Paper holding motor 44 Lowering detection sensor 44a Detection position of lowering detection sensor 45 Upper detection sensor 45a Detection position of uppering detection sensor 46 Paper press sensor 47 Paper surface detection lever 471 Main body part 472 Lever 474 Detection plate for lowering 475 Detection target plate for raising BS, BS1, BS2 Paper bundle ct Paper central part EG Paper leading edge EG Paper both ends PO1 Home position PO2, PO3 Tray full position RG1 area SH paper

Claims (16)

Binding means for generating a bundle of sheets by binding a plurality of sheets;
Discharging means for discharging the sheet bundle generated by the binding means;
A stacking unit for stacking the sheet bundle discharged by the discharging unit;
A counting means for counting the number of sheet bundles stacked on the stacking means or the number of sheets constituting the sheet bundle stacked on the stacking means;
A full judging means for judging that the loading means is full when the value counted by the counting means reaches a reference value;
A value setting unit configured to set the reference value based on an estimated curl state of sheets constituting a sheet bundle discharged by the discharge unit and a type of binding performed by the binding unit; Post-processing device. The value setting means sets the reference value based on whether the curl state is a back curl or a face curl,
The back curl is in a state in which both ends of the paper in the discharge direction in which the paper is discharged by the discharge means are curved upward from the center of the paper in the discharge direction
2. The post-processing according to claim 1, wherein the face curl is in a state in which both end portions of a sheet in a discharge direction in which the discharge unit discharges a bundle of sheets are curved below a central portion of the sheet in the discharge direction. apparatus.   The value setting means uses the reference value when the curl state and the binding type are a specific combination, and the reference value when the curl state and the binding type are not the specific combination. The post-processing apparatus according to claim 2, wherein the post-processing apparatus is set to a smaller value.   The post-processing apparatus according to claim 3, wherein the specific combination includes a combination in which the curl state is the back curl and the binding type is two-point binding.   The post-processing apparatus according to claim 3 or 4, wherein the specific combination includes a combination in which the curl state is the face curl and the binding type is one-point binding. The binding means generates a bundle of sheets by binding the plurality of printed sheets;
Print conditions set for printing the plurality of sheets, further comprising print condition acquisition means for acquiring print conditions for single-sided printing or double-sided printing;
The curl state is estimated based on whether the set printing condition is single-sided printing or double-sided printing and the type of the plurality of sheets. Post-processing device. When the full judging unit judges that the stacking unit is full during printing of the plurality of sheets, it further includes a continuation judging unit for judging whether or not to continue printing of the plurality of sheets. ,
The continuation determining means determines that printing is stopped when the number of sheets that have not been printed or the number of sheets is greater than a predetermined value,
The post-processing apparatus according to claim 6, wherein the continuation determination unit determines that the printing is continued when the number of sheets not printed or the number of sheets is equal to or less than the predetermined value.   When the curl state is the back curl, a speed setting for setting the speed at which the sheet bundle is ejected by the ejecting unit after the continuation determining unit determines to continue printing based on the binding type The post-processing apparatus according to claim 7, further comprising means.   When the type of binding is one-point binding, the speed setting means determines the speed at which the paper bundle is discharged by the discharging means after the continuation determining means determines to continue printing, the continuation determining means. The post-processing apparatus according to claim 8, wherein the speed is set to the same speed as the speed at which the sheet bundle is discharged by the discharging unit before determining that printing is to be continued.   When the binding type is two-point binding, the speed setting means determines the speed at which the paper bundle is discharged by the discharge means after the continuation determination means determines that printing is to be continued. The post-processing apparatus according to claim 8 or 9, wherein a speed slower than a speed of discharging the sheet bundle by the discharging means before determining that printing is to be continued is set. The loading means can be moved up and down,
When the curl state is the face curl, the apparatus further includes a position setting unit that sets a height position of the stacking unit after the continuation determining unit determines to continue printing based on the binding type. Furthermore, the post-processing apparatus in any one of Claims 7-10.   When the binding type is one-point binding, the position setting means prints the height position of the stacking means after the continuation determining means determines to continue printing, using the continuation determining means. The post-processing apparatus according to claim 11, wherein the post-processing apparatus is set to a position higher than a height position of the stacking unit before it is determined to continue.   When the binding type is two-point binding, the position setting means prints the height position of the stacking means after the continuation determining means determines that the printing is continued by the continuation determining means. The post-processing device according to claim 11 or 12, wherein the post-processing device is set to the same position as the height position of the stacking means before it is determined to continue.   The value setting means determines the reference value when the curl state is the back curl and the binding type is two-point binding, the curl state is the back curl, and the binding curl The post-processing device according to any one of claims 2 to 13, wherein the post-processing device is set to a value smaller than the reference value when the type is one-point binding.   The value setting means uses the reference value when the curl state is the face curl and the binding type is one-point binding, the curl state is the face curl, and the binding curl The post-processing apparatus according to any one of claims 2 to 14, wherein the post-processing device is set to a value smaller than the reference value when the type is two-point binding. A binding unit that generates a sheet bundle by binding a plurality of sheets, a discharge unit that discharges the sheet bundle generated by the binding unit, and a stacking unit that stacks the sheet bundle discharged by the discharge unit. A method of controlling the post-processing device,
A counting step of counting the number of sheet bundles stacked on the stacking means or the number of sheets constituting the sheet bundle stacked on the stacking means;
A full determination step of determining that the loading means is full when the value counted in the counting step reaches a reference value;
A post-processing apparatus comprising: a value setting step for setting the reference value based on an estimated curl state of a sheet bundle discharged by the discharge unit and a type of binding performed by the binding unit. Control method.