Post-processing device and program

Abstract

To allow for the neat and orderly storage of sheets that require post-processing. [Solution] The post-processing device 20 is a post-processing device that performs post-processing on an image-formed sheet (paper S), and comprises a storage tray 24 for storing the sheet to be processed by the post-processing device 20, an output tray 26 that receives the processed sheet from the storage tray 24 at a receiving position H1, a transport unit 22 that switches back the image-formed sheet to store it in the storage tray 24, and a control unit 21 that positions the output tray 26 at a holding position H2 where the step difference between the receiving position H1 and the storage tray 24 is smaller, in order to hold the end of the sheet on the output tray 26 side of the sheet that is switched back by the transport unit 22.

Description

Technical Field

[0001] The present invention relates to a post-processing device and a program.

Background Art

[0002] Conventionally, there is known a post-processing device that performs post-processing such as binding and punching on sheets discharged from image forming apparatuses such as copiers, printers, and multifunction peripherals. The post-processing device accommodates sheets discharged from the image forming apparatus in a storage tray, performs post-processing such as binding and punching in the storage tray, and then discharges the sheets to a paper discharge tray disposed on the downstream side of the storage tray.

[0003] Regarding this, Patent Documents 1 and 2 describe inventions for controlling the height of a paper discharge tray when discharging sheets after post-processing to the paper discharge tray (stack tray).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Examples of the operation of the post-processing device 20 are shown in FIGS. 8 to 10. In the post-processing device 20, as shown in FIG. 8, the sheet S discharged from the image forming apparatus is conveyed by conveying rollers such as an inlet roller 221 and a storage paper discharge roller 222. ​Subsequently, as shown in Figure 9, when the trailing end SE of the paper S in the transport direction passes the paper collection and discharge roller 222, the paper S falls onto the storage tray 24 which holds the paper to be processed. At this time, if the length of the paper S in the transport direction is relatively long, the paper S is supported across the paper discharge tray 26, which is loaded with processed paper, and the storage tray 24. In the post-processing device 20, the loading surface of the paper output tray 26 is positioned lower than the loading surface of the storage tray 24 so that the gripper 253a that holds the paper when the post-processed paper is ejected does not interfere with the paper output tray 26 or the paper stacked on the paper output tray 26. After the paper S is placed on the storage tray 24, as shown in Figure 10, the paper S is transported (switched back) towards the FD regulating plate 252 by the paddle unit 223 which has moved downward, and the rear end SE of the paper S in the transport direction abuts against the abutting surface 252a of the FD regulating plate 252. This ensures the quality of the booklet bundle by aligning the edges of the paper S before performing post-processing such as binding.

[0006] However, when the paper S is supported across the paper output tray 26 and the storage tray 24, where there is a relatively large step difference between the loading surface of the paper output tray 26 and the loading surface of the storage tray 24, and the paper S is switched back by the paddle unit 223, the paper S may bend at two points (C1, C2) in the transport direction, resulting in the paper S becoming S-shaped. In the post-processing device 20, in order to ensure that the rear end SE of the paper S in the transport direction abuts against the abutting surface 252a, the paddle unit 223 applies transport force to the paper S even after the rear end SE in the transport direction abuts against the abutting surface 252a. Therefore, if the paper S is in a bent state (S-shape), buckling Z is likely to occur due to this transport force. Once the paddle unit 223 completes the switchback of the paper S, the paddle unit 223 rises and returns to its original position. When the transport force from the paddle unit 223 is released, the paper S generates momentum to resolve the buckling Z and return to a straight position, causing the rear end SE of the paper S in the transport direction to separate from the abutment surface 252a. This disrupts the alignment of the paper S, which may lead to a problem where the quality of the booklet bundle after binding cannot be ensured.

[0007] The object of the present invention is to provide a post-processing device and program that can neatly accommodate sheets to be processed. [Means for solving the problem]

[0008] The post-processing apparatus according to claim 1 is: A post-processing device for performing post-processing on an image-formed sheet, A storage tray for storing sheets to be processed by the aforementioned post-processing device, A paper output tray that receives the processed sheets from the storage tray at a receiving position, A transport unit that switches back the image-formed sheet to place it into the storage tray, A control unit that positions the output tray at a holding position where the height difference between it and the storage tray is smaller than the receiving position, in order to hold the output tray side end of the sheet that is switched back by the transport unit, It is equipped with.

[0009] The invention described in claim 2 is a post-processing apparatus described in claim 1, The control unit changes the position of the output tray when holding the output tray side end of the sheet being switched back, according to the paper feeding mode, to the holding position or the receiving position.

[0010] The invention described in claim 3 is a post-processing apparatus described in claim 1, The end portion of the sheet to be switched back on the side of the paper discharge tray is held by the paper discharge tray surface or the uppermost sheet discharged onto the paper discharge tray.

[0011] The invention according to claim 4 is the post-processing apparatus according to claim 1, wherein The control unit changes the height of the receiving position so that the position of the uppermost surface of the sheet becomes constant according to the amount of sheets received by the paper discharge tray.

[0012] The program according to claim 5 is A post-processing apparatus that performs post-processing on an image-formed sheet, A storage tray that stores sheets to be post-processed by the post-processing apparatus, A paper discharge tray that receives the post-processed sheets at a receiving position from the storage tray, A transport unit that switches back the image-formed sheet to be stored in the storage tray, Causes a computer of a post-processing apparatus including To function as a control unit that positions the paper discharge tray at a holding position where the level difference from the storage tray is smaller than the receiving position in order to hold the end portion of the sheet on the paper discharge tray side that is switched back by the transport unit.

Advantages of the Invention

[0013] According to the present invention, sheets to be post-processed can be neatly stored.

Brief Description of the Drawings

[0014] [Figure 1] It is a diagram showing the overall configuration of an image forming system according to an embodiment. [Figure 2] It is a block diagram showing a schematic control configuration of an image forming system according to an embodiment. [Figure 3] It is a flowchart showing the flow of post-processing control processing executed by the post-processing apparatus. [Figure 4] It is a diagram for explaining the operation of the post-processing apparatus. [Figure 5] This is a diagram for explaining the operation of the post-processing device. [Figure 6] This is a diagram for explaining the operation of the post-processing device. [Figure 7] This is a diagram for explaining the operation of the post-processing device. [Figure 8] This is a diagram for explaining the operation of the post-processing device. [Figure 9] This is a diagram for explaining the operation of the post-processing device. [Figure 10] This is a diagram for explaining the operation of the post-processing device.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] [Overall Configuration of the Image Forming System] FIG. 1 is a diagram showing the overall configuration of the image forming system 1 according to this embodiment. FIG. 2 is a block diagram showing the schematic control configuration of the image forming system 1. As shown in FIGS. 1 and 2, the image forming system 1 includes an image forming apparatus 10 and a post-processing apparatus 20.

[0017] [Configuration of the Image Forming Apparatus] The image forming apparatus 10 is an MFP (Multifunction Peripheral), and forms an image on a sheet (paper) by an electrophotographic method based on print data. The image forming apparatus 10 includes a main body control unit 11, a paper feeding unit 12, an image forming unit 13, a scanner 14, an operation display unit 15, a communication unit 16, a storage unit 17, etc. Each part of the image forming apparatus 10 is connected by a bus.

[0018] The main control unit 11 includes a CPU (Central Processing Unit), RAM (Random Access Memory), etc. The CPU of the main control unit 11 reads and executes programs stored in the program storage area of ​​the memory unit 17, performs various calculations, and comprehensively controls each part of the image forming apparatus 10. The RAM of the main control unit 11 provides the CPU with a working memory space and temporarily stores data. The main control unit 11 operates each part of the image forming apparatus 10 based on image data stored in the storage unit 17 to form an image on paper.

[0019] The paper feeding unit 12 transports paper from one of the paper trays 121 to 123 to the image forming unit 13, depending on the job. Paper trays 121-123 store paper according to type, size, etc. When the user executes a job in the image forming system 1, they place the paper for the job into one of the paper trays 121 to 123. The main control unit 11 accepts input operations from the user via the operation display unit 15 for job setting information corresponding to the target paper.

[0020] The image forming unit 13 applies toner (colorant) to the paper supplied from the paper feeding unit 12 to form an image. The image forming unit 13 includes an intermediate transfer belt 131, an image forming unit 132, a transfer roller 133, and a fixing unit 134. The intermediate transfer belt 131 is an endless, strip-shaped member that is stretched around a plurality of rollers and moves in a circular motion.

[0021] The image forming unit 132 is positioned along the intermediate transfer belt 131 and forms toner images of C (cyan), M (magenta), Y (yellow), and K (black) on the intermediate transfer belt 131 based on image data relating to the image to be printed. As the paper passes through the nip between the intermediate transfer belt 131 and the transfer roller 133, the toner images are transferred to the paper and an image is formed. In this embodiment, an image forming unit 13 capable of forming a color image is illustrated, but it is not limited to this, and an image forming unit 13 capable of forming a monochrome image may also be used.

[0022] The fixing unit 134 heats and pressurizes the paper onto which the toner image has been transferred to fix the toner image to the paper. The paper with the toner image fixed is then sent to the post-processing device 20.

[0023] The scanner 14 includes a light source, an optical system such as a reflector, and an image sensor. The scanner 14 reads an image of paper being transported along a predetermined transport path or paper placed on a platen glass, generates image data, and outputs it to the main unit control unit 11. The main unit control unit 11 stores the generated image data in the storage unit 17.

[0024] The operation display unit 15 includes a display device such as a liquid crystal display, a touch panel superimposed on the screen of the display device, and input devices such as operation keys. The operation display unit 15 displays various information on the display device, such as the operating status and processing results of the image forming apparatus 10. The operation display unit 15 converts user input operations to the input devices into operation signals and outputs them to the main unit control unit 11.

[0025] The communication unit 16 is equipped with a network card, etc. The communication unit 16 is connected to a communication network such as a LAN (Local Area Network) and transmits and receives information with external devices on the communication network. The main control unit 11 communicates with external devices on the communication network via the communication unit 16.

[0026] The storage unit 17 includes a non-volatile storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory. The memory unit 17 includes a program storage area and a data storage area. The program storage area stores data for various programs. The data storage area stores, for example, image data acquired by the scanner 14, image data input from an external source via the communication unit 16, and the like.

[0027] (Configuration of post-processing equipment) The post-processing device 20 performs post-processing such as stapling on the paper transported from the image forming apparatus 10. The post-processing device 20 may also perform post-processing such as punching holes or folding. As shown in Figures 2 and 4, the post-processing device 20 includes a control unit 21, a transport unit 22, a storage tray 24, a stapling mechanism 25, a matching unit 254, a discharge unit 253, a paper output tray 26, a detection sensor 27, a top sensor 28, a storage unit 29, and the like.

[0028] The control unit 21 includes a CPU, RAM, etc. The CPU of the control unit 21 reads and executes programs stored in the program storage area of ​​the memory unit 29, performs various calculations, and comprehensively controls each part of the post-processing unit 20. The RAM of the control unit 21 provides the CPU with a working memory space and temporarily stores data.

[0029] The transport unit 22 is equipped with transport rollers such as an inlet roller 221 and a paper receiving and discharge roller 222. Each transport roller is paired with another to grip and transport the paper that has been transported from the image forming apparatus 10. The storage tray 24 is positioned below the storage and output roller 222. Once the paper transported by the transport unit 22 passes the storage and output roller 222, it is no longer restrained by any of the transport rollers, and therefore falls onto the storage tray 24.

[0030] The transport unit 22 includes a paddle unit 223. The paddle unit 223 is configured to rotate around the pivot point 223a, and can take on an elevated position where the paddle 223b is positioned above (see Figure 4) and a lowered position where the paddle 223b is positioned below (see Figure 5). When the paddle unit 223 is in its lowered position, the rotating paddle 223b causes the paper placed on the storage tray 24 to strike against the FD regulating plate 252 provided by the alignment unit 254.

[0031] The stapling mechanism 25 includes a stapling section 251. The stapling section 251 houses staples (not shown) and drives the staples into the stack of paper on the storage tray 24, which is pressed against the FD regulating plate 252 by the paddle 223b.

[0032] The matching unit 254 includes an FD regulating plate 252 and a CD regulating plate 254a. The FD regulating plate 252 aligns multiple sheets of paper in the paper transport direction (FD direction). The FD regulating plate 252 aligns multiple sheets of paper in the transport direction before post-processing such as stapling by the stapling unit 251 is performed. The CD aligning plate 254a aligns multiple sheets of paper in the width direction (CD direction). The CD aligning plate 254a aligns multiple sheets of paper in the width direction before post-processing such as stapling by the stapling section 251 is performed.

[0033] The discharge section 253 is equipped with a gripper 253a. The gripper 253a is provided with an endless belt 253b. The gripper 253a grasps the paper on the storage tray 24. The control unit 21 moves the endless belt 253b in a circular motion to transport the paper held by the gripper 253a and discharge it onto the output tray 26.

[0034] The output tray 26 receives the paper that has been gripped and transported by the gripper 253a. The output tray 26 protrudes from the side of the post-processing device 20 main body and supports the paper discharged from the output position E of the post-processing device 20 main body with its upper surface. The output tray 26 is supported so as to be movable (movable up and down) in the vertical direction within a predetermined range below the output position E, and so as to be located below the upper surface of the storage tray 24. The lifting motor 261 raises and lowers the paper output tray 26 under the control of the control unit 21.

[0035] The detection sensor 27 detects the paper being transported to the post-processing device 20. In this embodiment, the detection sensor 27 detects at least the leading edge SS and trailing edge SE of the paper S in the transport direction that have reached the paper storage and discharge roller 222. The detection sensor 27 in this embodiment is a through-type optical sensor. The type of sensor 27 is not particularly limited as long as it can detect paper (paper feeding), and may be an ultrasonic sensor, a reflective optical sensor, a touch sensor, etc.

[0036] The top sensor 28 is positioned at a height just below the paper output position E, and detects when the top surface of the paper output tray 26 or the paper on the paper output tray 26 is at that height and outputs a signal to the control unit 21.

[0037] The storage unit 29 is equipped with a non-volatile storage device such as an HDD, SSD, or flash memory. The memory unit 29 has a program storage area in which data for various programs, including a program that performs post-processing control processing described later, is stored.

[0038] [Operation of the image forming system] Figure 3 is a flowchart showing the operation of the post-processing control process that the post-processing device 20 performs after receiving the image-formed paper from the image forming apparatus 10. At the start of the post-processing control process, the paddle unit 223 is in the raised position and the output tray 26 is in the receiving position H1 (see Figures 6 and 7).

[0039] (Post-processing control) The control unit 21 acquires post-processing information from the image forming apparatus 10 (step S1). Post-processing information is information relating to post-processing performed by the post-processing device 20. If the post-processing is stapling, the post-processing information includes the type and size of the image-formed paper transported from the image forming apparatus 10, the number of sheets of paper to be stapled (specified number), the number of paper bundles created by the stapling (number of copies), etc. For example, the user sets post-processing information from the operation display unit 15 of the image forming apparatus 10. The types of paper for which images have been formed include, for example, thin paper, regular paper, thick paper 1, thick paper 2, thick paper 3, etc.

[0040] Next, the control unit 21 determines, based on the post-processing information acquired in step S1, whether the image-formed paper S transported from the image forming apparatus 10 is prone to buckling (step S2). Specifically, the control unit 21 determines, for example, that if the paper type S is thin paper or plain paper, the paper S is prone to buckling. On the other hand, the control unit 21 determines, for example, that if the paper type S is thick paper, the paper S is not prone to buckling.

[0041] If the paper S is prone to buckling (Step S2; YES), the control unit 21 controls the transport unit 22 to transport the image-formed paper S that has been transported from the image forming apparatus 10 using transport rollers such as the entrance roller 221, as shown in Figure 8 (Step S3).

[0042] Next, the control unit 21 detects the leading edge SS in the transport direction of the paper S that has reached the paper storage and discharge roller 222 using the detection sensor 27 (step S4). Next, the control unit 21 determines whether the paper S whose leading edge SS in the transport direction was detected in step S4 is the first sheet of paper in the stack created by the stapling process (step S5).

[0043] If the paper S is the first sheet in the stack of paper (step S5; YES), the control unit 21 controls the lifting motor 261 to start moving the output tray 26 to the holding position H2 (step S6). In this embodiment, the control unit 21 starts moving the output tray 26 to the holding position H2 after the detection sensor 27 detects the leading edge SS of the paper S in the transport direction. The control unit 21 completes the movement of the output tray 26 to the holding position H2 before starting step S9. The height difference between the holding position H2 and the top surface (mounting surface) of the storage tray 24 is smaller than the receiving position H1 of the output tray 26 when the stapled paper stack is ejected to the output tray 26.

[0044] On the other hand, if paper S is not the first sheet in the stack of paper (step S5; NO), the control unit 21 proceeds to the post-processing control step S8. If the paper S is not easily buckled (step S2; NO), the control unit 21 transports the paper S in the same manner as in step S3 (step S7), and proceeds to step S8 for post-processing control.

[0045] Next, as shown in Figure 4, the control unit 21 detects the rear end SE in the transport direction of the paper S that has reached the paper collection and discharge roller 222 using the detection sensor 27 (step S8). Once the paper S passes through the paper storage and output roller 222, it is no longer restrained by any of the transport rollers, and the paper S falls onto the storage tray 24. At this time, if the length of the paper S in the transport direction is relatively large, the paper S is supported across the output tray 26 and the storage tray 24. In other words, at this time, the leading edge SS of the paper S in the transport direction is held by the output tray 26 or the topmost sheet of paper loaded in the output tray 26.

[0046] When the detection sensor 27 detects the trailing end SE of the paper S in the transport direction, the control unit 21 switches the paper S back using the paddle unit 223, as shown in Figure 5 (step S9). Specifically, the control unit 21 rotates the paddle unit 223, which is in the raised position, counterclockwise around the pivot point 223a to move the paddle unit 223 to the lowered position. In the lowered position of the paddle unit 223, the paddle 223b makes contact with the paper S that has fallen onto the storage tray 24. Next, the control unit 21 rotates the paddle 223b counterclockwise to transport the paper S on the storage tray 24 towards the FD regulating plate 252, causing the rear end SE of the paper S in the transport direction to abut against the abutment surface 252a of the FD regulating plate 252. In order to ensure that the rear end SE of the paper S in the transport direction abuts against the abutment surface 252a, the control unit 21 continues to rotate the paddle 223b for a predetermined time after abutment, thereby continuing to apply transport force to the paper S.

[0047] If the paper S is prone to buckling (step S2; YES), in step S9, the output tray 26 is positioned at a holding position H2, which is higher than the receiving position H1. In other words, in step S9, the height difference between the top surface of the output tray 26 and the top surface of the storage tray 24 is smaller than when the output tray 26 is positioned at the receiving position H1. This reduces the bending of the paper S when the paddle 223b transports the paper S and abuts the rear end SE of the paper S against the abutting surface 252a. Therefore, buckling of the paper S can be suppressed, and irregularities in the alignment of the paper S can also be suppressed.

[0048] On the other hand, if the paper S is not prone to buckling (step S2; NO), in step S9, the output tray 26 is positioned at the receiving position H1. In this case, the height difference between the top surface of the output tray 26 and the top surface of the storage tray 24 is greater than when the output tray 26 is positioned at the holding position H2, but since the paper S is not prone to buckling, buckling of the paper S is unlikely to occur.

[0049] As described above, the control unit 21 changes the position of the output tray 26 when holding the output tray 26 side end (leading end SS in the transport direction) of the paper S that is switched back by the paddle unit 223, according to the paper feeding mode which indicates whether the paper S is paper that is prone to buckling or paper that is not prone to buckling, to the holding position H2 or the receiving position H1.

[0050] Next, the control unit 21 rotates the paddle unit 223, which is in the lowered position, clockwise around the pivot point 223a to return the paddle unit 223 to the raised position (step S10). Next, the control unit 21 determines whether or not the specified number of sheets S set in the post-processing information have been properly placed on the storage tray 24 (step S11). If the specified number of sheets of paper S are not stored in the storage tray 24 (step S11; NO), the control unit 21 proceeds to step S3 for post-processing control. In other words, the control unit 21 repeats steps S3 to S11 until the specified number of sheets of paper S are stored in the storage tray 24.

[0051] On the other hand, when a specified number of sheets of paper S are placed on the storage tray 24 (step S11; YES), the control unit 21 performs stapling as a post-processing step (step S12). As a specific example, the control unit 21 uses the stapling unit 251 to staple a specified number of sheets of paper S together to create a paper stack ST (see Figure 6).

[0052] Next, the control unit 21 determines whether the current position of the output tray 26 is the holding position H2 (step S13). If the current position of the output tray is the holding position H2 (step S13; YES), the control unit 21 controls the lifting motor 261 to start moving the output tray 26 to the receiving position H1 (step S14). The movement of the output tray 26 to the receiving position H1 is completed before step S16 begins. This prevents the operation of the gripper 253a from being obstructed by the paper output tray 26 or the paper stacks placed on the paper output tray 26 when the paper stack ST is discharged onto the paper output tray 26. On the other hand, if the current position of the output tray 26 is the receiving position H1 (step S13; NO), the control unit 21 proceeds to step S15 for post-processing control.

[0053] Next, the control unit 21 grips the stapled paper bundle ST with the gripper 253a, as shown in Figure 6 (step S15). Specifically, the control unit 21 causes the endless belt 253b to rotate, moving the gripper 253a counterclockwise from the standby position shown in Figure 5 to the end STE of the paper stack ST. The gripper 253a, whose end face 253aa is engaged with the endless belt 253b, moves along with the movement of the endless belt 253b. A portion of the gripper 253a engages with a rail groove (not shown), and opens and closes due to the movement by the endless belt 253b and the trajectory of the rail groove. The shape of the rail groove is set to open at the end STE, which is just before the position where the gripper 253a grips the paper. Next, the gripper 253a opens, and the end face 253aa of the gripper 253a comes into contact with the end STE of the paper stack ST. Subsequently, as the endless belt 253b continues its rotational movement, the gripper 253a disengages from the rail groove, and the spring biasing force closes 253a, causing the gripper 253a to grip the paper stack ST.

[0054] Next, the control unit 21 causes the endless belt 253b to rotate, and the paper bundle ST is conveyed while being gripped by the gripper 253a (step S16). Next, the control unit 21 discharges the paper stack ST onto the output tray 26, as shown in Figure 7 (step S17). The end face 253aa of the gripper 253a is located inside the wall surface 30 of the post-processing device 20 (on the opposite side of the paper output tray 26) at the end of the endless belt 253b on the paper output tray 26 side. When the end STE of the paper output tray ST hits the wall surface 30 during the process in which the gripper 253a moves along the endless belt 253b while gripping the paper stack ST, the paper stack ST is pulled out from the gripper 253a and placed on the paper output tray 26.

[0055] Next, the control unit 21 uses the top surface sensor 28 to detect the top surface of the paper output tray 26 or the top surface of the stack of paper ST on the paper output tray 26, which is the stacked top surface (step S18). Next, the control unit 21 controls the lifting motor 261 to lower the output tray 26 so that the top surface of the stack detected in step S18 is at a predetermined height, thereby changing the receiving position H1 (step S19). This prevents interference between the gripper 253a, which holds the paper stack, and the paper stack placed on the paper output tray 26 when the paper stack is discharged to the output tray 26.

[0056] Next, the control unit 21 determines whether or not the ejection of all the paper bundles ST set in the post-processing information has been completed (step S20). If the ejection of all stacks of paper ST has not been completed (step S20; NO), the control unit 21 proceeds to step S3 for post-processing control. On the other hand, once the ejection of all paper stacks ST is complete (step S20; YES), the control unit 21 terminates the post-processing control process.

[0057] [Technical effects of this embodiment] As described above, the post-processing device 20 according to this embodiment is a post-processing device that performs post-processing on an image-formed sheet (paper S). The post-processing device 20 according to this embodiment includes a storage tray 24 for storing sheets to be processed by the post-processing device 20. The post-processing device 20 according to this embodiment includes an output tray 26 that receives the post-processed sheets from the storage tray 24 at a receiving position H1. The post-processing device 20 according to this embodiment includes a transport unit 22 that switches back the image-formed sheet to accommodate it in a storage tray 24. The post-processing device 20 according to this embodiment includes a control unit 21 that positions the output tray 26 at a holding position H2 where the step difference with the storage tray 24 is smaller than that between the receiving position H1 and the output tray 26, in order to hold the output tray 26 side end of the sheet that is switched back by the transport unit 22. Therefore, the paper S can be held across the paper output tray 26 and the paper storage tray 24, where the height difference between the upper surface of the paper output tray 26 and the upper surface of the paper storage tray 24 is smaller than the receiving position H1, at a holding position H2. This reduces the bending of the paper S when the paddle 223b switches the paper S back and abuts the rear end SE in the transport direction against the abutment surface 252a. Consequently, buckling of the paper S can be suppressed, and irregularities in the alignment of the paper S can also be suppressed. This allows for the neat and organized storage of sheets (paper) that require post-processing.

[0058] In the post-processing device 20 according to this embodiment, the control unit 21 changes the position of the output tray 26 when holding the output tray side end (leading end SS in the transport direction) of the sheet (paper S) that is being switched back, according to the paper feeding mode, to either the holding position H2 or the receiving position H1. Therefore, if the paper is not prone to buckling, the process of moving the output tray 26 from the receiving position H1 to the holding position H2 can be omitted.

[0059] In the post-processing device 20 according to this embodiment, the end of the sheet (paper S) that is switched back, on the side of the paper output tray 26 (leading end SS in the transport direction), is held by the surface of the paper output tray 26 or the uppermost sheet that has been output to the paper output tray 26. Therefore, even when the paper S is supported across the stepped upper surface of the output tray 26 and the upper surface of the storage tray 24, and is switched back by the paddle unit 223, the bending of the paper S can be reduced by making the step smaller than the receiving position H1.

[0060] In the post-processing device 20 according to this embodiment, the control unit 21 changes the height of the receiving position H1 so that the position of the top surface of the sheet remains constant, according to the amount of sheets (paper S) received by the output tray 26. Therefore, when discharging the stack of paper into the output tray 26, the gripper 253a that holds the stack of paper and the stack of paper placed on the output tray 26 can be prevented from interfering with each other.

[0061] [others] Although one embodiment of the present invention has been described above, the embodiments to which the present invention can be applied are not limited to the embodiments and their modifications described above, and can be modified as appropriate without departing from the spirit of the present invention.

[0062] For example, in step S2 of the post-processing control process of the above embodiment, the control unit 21 determines that if the paper type is thin paper or plain paper, the paper is prone to buckling, and if the paper type is thick paper, the paper is not prone to buckling, but is not limited to this. The control unit 21 may also determine whether the paper is prone to buckling or not based on the size of the paper, basis weight, etc. [Explanation of Symbols]

[0063] 1. Image forming system 10 Image forming apparatus 11 Main Unit Control 12 Paper feed section 13 Image forming unit 14 Scanners 15 Operation display section 16 Communications Department 17 Memory section 20 Post-processing equipment 21 Control Unit 22 Conveying section 221 Entrance Roller 222 Paper output roller 223 Paddle Unit 24 storage trays 25 Staple mechanism 251 Staple section 254 Matching section 252 FD restriction board 254a CD regulation plate 253 Discharge section 253a Gripper 26 Paper output tray 27 Detection Sensors 28 Top sensor 29 Memory section H1 Receiving location H2 holding position S paper ST paper stack

Claims

1. A post-processing device for performing post-processing on an image-formed sheet, A storage tray for storing sheets to be processed by the aforementioned post-processing device, A paper output tray that receives the processed sheets from the storage tray at a receiving position, A transport unit that switches back the image-formed sheet to place it into the storage tray, A control unit that positions the output tray at a holding position where the height difference between it and the storage tray is smaller than the receiving position, in order to hold the output tray side end of the sheet that is switched back by the transport unit, A post-processing device equipped with the following:

2. The post-processing device according to claim 1, wherein the control unit changes the position of the output tray when holding the output tray side end of the sheet to be switched back, according to the paper feeding mode, to the holding position or the receiving position.

3. The post-processing device according to claim 1, wherein the end of the sheet that is switched back on the paper output tray side is held by the surface of the paper output tray or the uppermost sheet that has been output to the paper output tray.

4. The post-processing device according to claim 1, wherein the control unit changes the height of the receiving position according to the amount of sheets received by the output tray so that the position of the top surface of the sheets remains constant.

5. A post-processing device for performing post-processing on an image-formed sheet, A storage tray for storing sheets to be processed by the aforementioned post-processing device, A paper output tray that receives the processed sheets from the storage tray at a receiving position, A transport unit that switches back the image-formed sheet to place it into the storage tray, A computer for a post-processing device equipped with, A program that functions as a control unit, which positions the output tray at a holding position where the height difference between it and the storage tray is smaller than the receiving position, in order to hold the output tray side end of the sheet that is switched back by the transport unit.

Images