Sheet processing apparatus, image forming apparatus, and image forming system

Abstract

In a sheet processing device that performs folding on a sheet, the folding height of the sheet after the folding process is reduced. [Solution] A sheet processing device comprising: a plurality of conveying means for conveying a sheet; a sheet deflection detection means for detecting the amount of deflection of the sheet in the conveying direction; and a control means for controlling the operation of the conveying means to perform a folding process on the conveyed sheet, wherein the control means controls the operation of the conveying means to perform additional folding on the creases formed in the folding process, for a number of times set according to the amount of deflection and the thickness of the sheet.

Description

Technical Field

[0006] , , , ,

[0001] The present invention relates to a sheet processing apparatus, an image forming apparatus, and an image forming system.

Background Art

[0002] There are known sheet processing apparatuses that perform alignment processing for aligning the ends of a plurality of sheet-like media (sheets), folding processing for folding the media, and the like. There are also known image forming apparatuses having a function corresponding to a sheet processing apparatus and a function of forming an image on a sheet. Further, an image forming system composed of a sheet processing apparatus and an image forming apparatus is also known.

[0003] In a sheet processing apparatus provided with folding means, a configuration for increasing the pressing force of a folding roller and a double-folding roller is disclosed for the purpose of reducing the folding height of a folded bundle (see Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, the problem that the operation amount control of the alignment operation cannot be performed for the alignment in the width direction when the paper size or the paper thickness changes has not been solved.

[0005] [[ID=​​​​​​To solve the above technical problems, one aspect of the present invention relates to a sheet processing apparatus for performing a folding process on a sheet, comprising: a plurality of conveying means for conveying the sheet; a sheet deflection detection means for detecting the amount of deflection of the sheet in the conveying direction; and a control means for controlling the operation of the conveying means to perform the folding process on the conveyed sheet, wherein the control means controls the operation of the conveying means to perform additional folding on a crease formed in the folding process, for a number of times set according to the amount of deflection and the thickness of the sheet. [Effects of the Invention]

[0007] According to the present invention, the folded height of the sheet after the folding process can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram showing an embodiment of an image forming apparatus including a sheet processing apparatus according to the present invention. [Figure 2] A schematic diagram showing another embodiment of an image forming apparatus including a sheet processing apparatus according to the present invention. [Figure 3] A schematic diagram showing an embodiment of the image forming system according to the present invention. [Figure 4] A block diagram showing an example of the control configuration according to the above embodiment. [Figure 5] Internal configuration diagram of the sheet processing unit according to the above embodiment. [Figure 6] An enlarged internal diagram showing one step of the folding and conveying operation in the sheet processing unit described above. [Figure 7] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 8] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 9] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 10] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 11] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 12] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 13] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 14] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 15] Enlarged internal diagram showing one step of the folding and transport operation described above. [Figure 16] An enlarged view showing the configuration of the additional folding mechanism provided in the sheet processing unit described above. [Figure 17] An enlarged view showing the configuration of the hardness detection mechanism provided in the sheet processing unit described above. [Figure 18] This figure shows an example of paper hardness detection using the hardness detection mechanism described above. [Figure 19] This figure shows an example of paper hardness detection using the hardness detection mechanism described above. [Figure 20] A flowchart illustrating an example of the processing operation of the sheet processing unit according to this embodiment. [Figure 21] A flowchart illustrating an example of the processing operation of the sheet processing unit according to this embodiment. [Modes for carrying out the invention]

[0009] [Embodiment of an Image Forming Apparatus] An embodiment of the image forming apparatus according to the present invention will now be described. Figure 1 is a schematic diagram of a printer 10 as an image forming apparatus. The printer 10 has a printer unit 100 as an image forming unit that forms an image on a sheet-like medium, and a sheet processing unit 200 which is connectable to the printer unit 100 and performs a predetermined sheet processing (for example, folding) on ​​the medium. In the following description, "paper P" will be used as an example of a sheet-like embodiment.

[0010] As shown in FIG. 1, the printer 10 is of an in-body discharge type that discharges the paper P on which an image is formed to the inside of the exterior of the housing. The printer 10 is configured by incorporating a sheet processing unit 200 into a part of the printer unit 100, which is the in-body space where the paper P is discharged. The discharge destination of the paper P on which an image is formed is the sheet processing unit 200 in the printer 10. In the printer 10, the sheet processing unit 200 is configured to be detachable from the printer unit 100. If an image forming process is executed in the printer 10 with the sheet processing unit 200 removed from the printer unit 100, the paper P on which an image is formed is discharged into the in-body space of the printer unit 100. The internal configuration of the sheet processing unit 200 will be described later.

[0011] [Another Embodiment of the Image Forming Apparatus] Also, as another embodiment of the image forming apparatus according to the present invention, a printer 10a as illustrated in FIG. 2 is also assumed. The printer 10a includes a functional configuration (sheet processing unit 200a) corresponding to the sheet processing unit 200 inside the housing (printer unit 100a). The printer 10a integrally configures the sheet processing unit 200a with the printer unit 100a.

[0012] Note that the sheet processing unit 200a has the same configuration as the sheet processing unit 200 and exhibits the same operational effects. In the following description, the detailed internal configuration of the sheet processing unit 200a will be omitted.

[0013] [Embodiment of the Image Forming System] FIG. 3 is a schematic diagram showing the schematic configuration of a printer system 1 as an embodiment of the image forming system according to the present invention. In FIG. 3, the printer system 1 is configured by connecting a printer 100b and a sheet processing apparatus 200b. The printer system 1 operates such that the paper P on which an image is formed by the printer 100b is conveyed to the sheet processing apparatus 200b and predetermined sheet processing (for example, folding processing) is performed in the sheet processing apparatus 200b.

[0014] The sheet processing device 200b is configured to have the same functions as the sheet processing unit 200 and to produce equivalent effects. The specific internal configuration of the sheet processing device 200b will be omitted in the following description.

[0015] [Functional configuration of the control block] Next, an embodiment of the control unit that controls the operation of the printer unit 100 and the sheet processing unit 200 as an embodiment of the sheet processing device according to the present invention will be described with reference to Figure 4. As shown in Figure 4, the printer unit 100 includes a printer control unit 110 as a control block. The printer control unit 110 includes a CPU (Central Processing Unit) 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, and a serial I / F 114.

[0016] The printer control unit 110 is connected to, for example, an image creation unit 120, an image reading unit 130, and a printer operation display unit 140. The image creation unit 120, the image reading unit 130, and the printer operation display unit 140 each contain configurations for performing their respective functions. Each configuration of the image creation unit 120, the image reading unit 130, and the printer operation display unit 140 operates based on control signals from the printer control unit 110.

[0017] The image creation unit 120 is configured to perform image formation processing on paper P based on image data. The image reading unit 130 is configured to read the image formed on paper P and acquire image data. The printer operation display unit 140 has functions that combine an input unit for inputting operating conditions for the image creation unit 120 and the image reading unit 130, and a display unit for displaying operating results, etc.

[0018] The printer operation display unit 140 also has the function of being both a display unit for the processing content in the printer control unit 110 and the sheet processing control unit 210, and an input unit that accepts and sets setting information (job information, sheet processing information) for controlling the operation (behavior) of the printer control unit 110 and the sheet processing unit 200.

[0019] The control program for controlling the image creation unit 120, the image reading unit 130, and the printer operation display unit 140 is stored in ROM 112. The CPU 111 reads the control program stored in ROM 112 and loads it into RAM 113. The CPU 111 then stores the data necessary for control in RAM 113 and executes the control defined by the control program while using RAM 113 as a work area.

[0020] Furthermore, as shown in Figure 4, the sheet processing unit 200 includes a sheet processing control unit 210 as a control block. The sheet processing control unit 210 includes a CPU 211, a ROM 212, a RAM 213, and a serial I / F 214.

[0021] The sheet processing control unit 210 is connected to various loads 220, various sensors 240, and a sheet processing operation display unit 250. The various loads 220 include rollers and roller pairs, which will be described later. The rollers and roller pairs corresponding to the various loads 220 constitute transport roller pairs and folding roller pairs, respectively. The various loads 220 are operated by drive motors that rotate each roller and each roller pair. The drive motors that make up the various loads 220 are operated by drivers 230 that receive instructions from the sheet processing control unit 210. The various loads 220 are configured to control the transport and folding of the paper P.

[0022] The various sensors 240 are multiple sheet detection means for detecting the position of the paper P within the transport path, and are arranged in multiple locations within the transport path, as described later. The amount and position of the paper P to be processed are determined by the sheet processing control unit 210 processing according to a predetermined control program based on detection signals output by the various sensors 240 to the sheet processing control unit 210. The position of the paper P can be determined by the sheet processing control unit 210 calculating the amount (transport distance) of the paper P based on the operating amount of the various loads 220 after the leading edge of the paper P is detected by the sheet detection means.

[0023] The sheet processing operation display unit 250 has the same functions as the printer operation display unit 140. Therefore, it has the function of both a display unit for processing content in the printer control unit 110 and the sheet processing control unit 210, and an input unit that accepts and sets setting information (job information, sheet processing information) for controlling the operation (behavior) of the printer control unit 110 and the sheet processing unit 200. In the printer system 1, the input of setting information may be performed in either the printer operation display unit 140 or the sheet processing operation display unit 250.

[0024] For example, when setting information is input and set in the printer operation display unit 140, the setting information (job information, sheet processing information) for controlling the operation (behavior) of the sheet processing unit 200 may be stored in the storage means of the sheet processing unit 200 (for example, a storage area implemented in RAM 213). In this case, when the sheet processing control unit 210 executes sheet processing, it may read the setting information stored in RAM 213 and execute sheet transport, folding, processing at the fold line position, etc., based on the settings included in the setting information.

[0025] The control program for the sheet processing control unit 210 to execute predetermined processing functions is stored in the ROM 212. The CPU 211 reads the control program stored in the ROM 212 and loads it into the RAM 213. The CPU 211 then stores the data necessary for control in the RAM 213 and uses the RAM 213 as a work area to execute the control of the folding operation defined by the control program. As described above, by the sheet processing control unit 210 executing the control program stored in the ROM 212, the detection of the paper P and the transport control of the paper P, which will be described later, can be performed.

[0026] Furthermore, RAM 213 may temporarily store "jobs" consisting of a group of information containing instruction information for specifying the content of sheet processing to be performed in the sheet processing unit 200. A job includes attribute information of the paper P and processing information specifying how to process the paper P. RAM 213 also stores the processing status of jobs. Therefore, when a job in progress is interrupted, information indicating the interruption status is also stored.

[0027] Furthermore, the ROM 212 may pre-store setting information for predetermined operations to perform sheet processing (sheet transport processing, sheet folding processing, sheet crease processing, etc.). In this case, the sheet processing control unit 210 performs sheet processing based on the setting information stored in the ROM 212.

[0028] The printer control unit 110 of the printer unit 100 and the sheet processing control unit 210 of the sheet processing unit 200 are connected via serial I / F 114 and serial I / F 214 to enable communication. This communication path is used to exchange control commands and information necessary for controlling the transport of the paper P. Based on the control commands and attribute information of the paper P sent from the printer unit 100 and the position information of the paper P obtained from various sensors 240, the sheet processing unit 200 switches the transport control of the paper P, whether or not folding is performed, whether or not additional folding is performed, and the type of folding.

[0029] The information (attribute information) regarding the paper P sent from the printer unit 100 (printer control unit 110) to the sheet processing unit 200 (sheet processing control unit 210) includes multiple pieces of information. For example, it includes multiple sheet type information indicating the type (material), thickness (rigidity), and size of the paper P received from the printer unit 100 to the sheet processing unit 200. This information also includes sheet processing information, such as specifying the overlap quantity of the paper P, the type of folding process for the paper P, and the folding position of the paper P. Furthermore, the control command notified from the printer control unit 110 to the sheet processing control unit 210 includes whether or not the received paper P corresponds to the last page (final sheet) of a unit that is processed as a whole.

[0030] In this embodiment, the operation of the sheet processing unit 200 described below may be performed by the printer control unit 110. In that case, the control program that the sheet processing control unit 210 executes to realize a predetermined processing function is stored in the ROM 112, and the CPU 111 reads and executes the control program stored in the ROM 112.

[0031] [Embodiment of Sheet Processing Device] Next, a sheet processing unit 200 as one embodiment of the sheet processing apparatus according to the present invention will be described. Figure 5 is a schematic diagram showing the internal configuration of the sheet processing unit 200. The sheet processing unit 200 includes a plurality of transport paths, a plurality of roller pairs for transporting paper P in each transport path and performing folding processing, and a plurality of sheet detection sensors for detecting the transport position of the paper P. Each of the plurality of roller pairs constitutes either a transport means or a folding means.

[0032] The sheet processing unit 200 has seven main transport paths. As shown in Figure 5, it has a first transport path W1, a second transport path W2, a third transport path W3, a fourth transport path W4, a fifth transport path W5, a sixth transport path W6, and a seventh transport path W7.

[0033] Furthermore, each of the first transport path W1, second transport path W2, third transport path W3, fourth transport path W4, fifth transport path W5, sixth transport path W6, and seventh transport path W7 is equipped with multiple transport roller pairs for transporting the paper P in a predetermined direction along these paths. In other words, the transport paths for transporting the paper P are equipped with transport roller pairs that constitute the 0th transport means R0, 1st transport means R1, 2nd transport means R2, 3rd transport means R3, 4th transport means R4, 5th transport means R5, 6th transport means R6, 7th transport means R7, and 8th transport means R8, each positioned at their respective locations. The rotation start and stop of each of these transport roller pairs as transport means are controlled by a control program executed by the sheet processing control unit 210 to start and stop in a predetermined direction. This control enables the transport and cessation of the transport of the paper P.

[0034] Furthermore, the fifth transport path W5 is equipped with a reinforcement roller R9 for performing a "reinforcement folding process" that further presses on the crease formed in the first folding process to strengthen the crease. As shown in Figure 5, a reinforcement folding mechanism F3 is positioned opposite the reinforcement folding roller R9 in the fifth transport path W5.

[0035] Furthermore, a stiffness detection mechanism F4 for detecting the stiffness of the paper P is positioned in the first transport path W1. The stiffness detection mechanism F4 detects the amount of deflection of the paper P that occurs when correcting disturbances in the transport posture of the paper P by stopping the operation of the first transport means, which functions as a register roller, when the paper P reaches the nip of the first transport means, while transport by the 0th transport means continues. Disturbances in the transport posture of the paper P refer to the so-called "skew," where the paper P is tilted relative to the transport direction. This disturbance in the transport posture is sometimes expressed as "skew," and correcting it is sometimes expressed as "performing skew correction." The stiffness detection mechanism F4 constitutes a sheet deflection detection means.

[0036] Furthermore, the sheet processing unit 200 is equipped with multiple transport branching means. These transport branching means can, for example, switch between transporting the paper P from the first transport path W1 to the second transport path W2, and transporting the paper P that has been transported to the second transport path W2 back to the first transport path W1. The transport branching means can also, for example, switch between transporting the paper P from the second transport path W2 back to the first transport path W1 while simultaneously transporting it to the third transport path W3, and then transporting it to a circulating transport path that circulates the paper P.

[0037] Furthermore, the multiple transport branching means can also perform switching operations to transport the paper P to the fourth transport path W4, which is downstream of the second transport path W2, instead of sending it to the circulating transport path.

[0038] Furthermore, the multiple transport branching means can also switch the transport route from the first transport path W1 through the third transport path W3 to the fifth transport path W5, which is downstream of the second transport path W2. In this way, the multiple transport branching means provided in the sheet processing unit 200 perform the switching of transport paths.

[0039] The multiple transport branching means are configured as, for example, a first transport branching means J1, a second transport branching means J2, and a third transport branching means J3, as shown in Figures 6 to 15. These multiple transport branching means are included in the various loads 220 whose operation is controlled by the sheet processing control unit 210. Therefore, the sheet processing control unit 210 controls the formation of the transport path for the paper P by controlling the operation of the multiple transport branching means. In addition, a first folding means F1 and a second folding means F2 for folding the paper P are also arranged along the circulating transport path.

[0040] The sheet processing unit 200 has a first transport means R0 positioned near the inlet 21 that receives sheets from the printer unit 100, with the first transport means R0 positioned as an inlet transport roller pair. The first transport means R0 is driven by a drive motor that starts rotating when the sheet processing control unit 210 receives information that the paper P has been ejected from the printer unit 100. Subsequently, when the leading edge of the paper P reaches the nip of the roller pair of the first transport means R0, the first transport means R0 transports the paper P downstream.

[0041] As described later, before the sheet processing unit 200 discharges the paper P fed in from the printer unit 100 from the downstream exit 22, it receives the next sheet P and performs a transport process where the previous sheet P and the subsequent sheet P are stacked together, and also performs a folding process with the previous sheet P and the subsequent sheet P stacked together. For the purposes of the following explanation, the preceding sheet P will be referred to as "preceding sheet P1". The sheet P that is received by the sheet processing unit 200 immediately after preceding sheet P1 will be referred to as "successor sheet P2". The sheet P that is received by the sheet processing unit 200 after successor sheet P2 and is subject to stacking will be referred to as "next sheet P3". A sheet bundle (a bundle of multiple sheets) formed by stacking multiple sheets of paper P will be referred to as "sheet bundle Q".

[0042] In the following description, the number of sheets of paper P used when performing overlapping and folding operations in the sheet processing unit 200 is assumed to be three. However, the overlapping and folding operations that can be performed in the sheet processing unit 200 according to this embodiment are not limited to this number. In other words, the overlapping and folding operations that can be performed in the sheet processing unit 200 are not limited by a specific number of sheets, but are selectively determined by the attributes of the paper P to be processed and the manner of processing applied to the paper P.

[0043] The first transport means R1 consists of a pair of rollers facing each other across the first transport path W1, forming a nip between the rollers. The first folding means F1 is positioned facing each other between the first transport path W1 and the second transport path W2, forming a nip between them. The path guided by this nip leads the preceding paper P1 from the first transport path W1 to the second transport path W2.

[0044] Furthermore, the third transport means R3 guides the preceding paper P1, which has been led to the second transport path W2, to the third transport path W3, where it is temporarily stopped. In other words, the transport of the preceding paper P1 is stopped midway through the third transport path W3. The transport of the preceding paper P1, which has been temporarily stopped in the third transport path W3, is resumed when the subsequent paper P2 is received from the printer unit 100. As a result, the preceding paper P1 returns to the upstream side of the first transport means R1 in the first transport path W1 and merges with the subsequent paper P2. In this way, a circulating transport path is configured such that it branches from the first transport path W1 to the second transport path W2 and returns to the upstream side of the first transport path W1 via the third transport path W3.

[0045] In the circulating transport path described above, the preceding paper P1 and the following paper P2 are stacked to form a paper bundle Q. Next, the flow of the folding process when folding is performed on the paper bundle Q will be explained.

[0046] The folding process for the paper stack Q is performed by a first folding means F1, which is operated under the control of the sheet processing control unit 210. The paper stack Q, after being folded by the first folding means F1, is then transferred from the second transport path W2 to the fifth transport path W5. The fourth transport means R4, the fifth transport means R5, and the first folding means F1 are all driven by the same drive motor. The drive motor is rotatable in both forward and reverse directions, and by changing the direction of rotation, the paper stack Q, with the preceding paper P1 and the following paper P2 stacked on top of each other, is transported and the folding process is performed again.

[0047] Furthermore, a branching claw 23 is positioned immediately after the sixth transport means R6. The branching claw 23 switches its guide position depending on whether the paper P (paper bundle Q) is guided to the sixth transport path W6 side or to the seventh transport path W7 side. The branching claw 23 can switch its position using, for example, a solenoid. Alternatively, a drive mechanism including a motor, gears, cams, etc., can be used instead of a solenoid.

[0048] Paper P that has passed through the fourth transport path W4 or the fifth transport path W5 is discharged into the discharge tray 24 of the sheet processing unit 200 and loaded. The seventh transport path W7 is a path for transferring paper P to a post-processing device when a post-processing device is provided downstream of the sheet processing unit 200 as part of the image forming system. In the post-processing device, post-processing such as alignment processing and binding processing is performed on paper P that has been folded or paper P that has not been folded.

[0049] Furthermore, paper P that has passed through the fifth transport path W5 is subjected to an additional folding process using the additional folding mechanism F3 under predetermined conditions.

[0050] A first sheet detection sensor SN1 is positioned immediately after the 0th conveying means R0 in the first conveying path W1. A second sheet detection sensor SN2 is positioned immediately before the first conveying means R1. A third sheet detection sensor SN3 is positioned immediately after the second conveying means R2 in the third conveying path W3. A fourth sheet detection sensor SN4 is positioned immediately after the third conveying means R3 in the third conveying path W3. A fifth sheet detection sensor SN5 is positioned immediately after the fourth conveying means R4 in the fourth conveying path W4. A sixth sheet detection sensor SN6 is positioned immediately after the fifth conveying means R5 in the fifth conveying path W5. A seventh sheet detection sensor SN7 is positioned immediately after the sixth conveying means R6 in the sixth conveying path W6.

[0051] Furthermore, the sixth sheet detection sensor SN6, located in the fifth transport path W5, is a sensor that detects when the fold position of the paper P or paper stack Q reaches a predetermined position when the additional folding process is performed in the additional folding mechanism F3. In other words, the sixth sheet detection sensor SN6 corresponds to an additional folding sensor.

[0052] The first sheet detection sensor SN1, the second sheet detection sensor SN2, the third sheet detection sensor SN3, the fourth sheet detection sensor SN4, the fifth sheet detection sensor SN5, the sixth sheet detection sensor SN6, the seventh sheet detection sensor SN7, and the eighth sheet detection sensor SN8, which serve as sheet detection means, detect the position of the paper P during transport.

[0053] Furthermore, based on the detection results of these sheet detection sensors, the sheet processing control unit 210 controls the operation of each transport means based on the position of the paper P. Also, based on the detection results of these sheet detection sensors, the sheet processing control unit 210 determines whether there are any remaining sheets in each transport path when the job is interrupted, and their locations.

[0054] [Example of overlay operation] The sheet processing unit 200 illustrated in Figure 6 can perform inner and outer tri-folds while the sheets of paper P are stacked. Figures 6 to 12 illustrate a series of operations for generating a paper bundle Q by stacking two sheets of paper P via a circulating transport path. Note that the illustration of the additional folding mechanism F3 is omitted in Figures 6 to 15, which are referenced in the following explanation.

[0055] Figure 6 shows the initial state before the paper P is transported from the printer unit 100. In the state shown in Figure 6, when the leading edge of the preceding paper P1 transported from the printer unit 100 reaches the paper output slot of the printer unit 100, the sheet processing control unit 210 starts rotating the 0th transport means R0.

[0056] As shown in Figure 7, the rotation of the 0th transport means R0 causes the preceding sheet P1 to be transported to the 1st transport path W1. In order to transport the preceding sheet P1 to the 2nd transport path W2 instead of the 4th transport path W4 and guide it to the circulating transport path, the sheet processing control unit 210 moves the 1st transport branching means J1 to the position shown in Figure 7.

[0057] When the leading edge of the preceding sheet P1, which has been transported by the 0th transport means R0, is detected by the 1st sheet detection sensor SN1, a detection signal is notified to the sheet processing control unit 210. Upon receiving the detection signal, the sheet processing control unit 210 calculates the timing at which the amount of protrusion of the leading edge of the sheet P reaches a predetermined value from the nip position of the 1st transport means R1. The amount of protrusion of the leading edge of the sheet P from the nip position of the 1st transport means R1 is referred to as the "1st protrusion amount Δ1". At the timing when the 1st protrusion amount Δ1 is reached, the rotation of the 1st transport means R1 is started.

[0058] When the leading edge of the preceding sheet P1 enters the nip of the first transport means R1, the sheet processing control unit 210 starts the rotational operation of the first folding means F1, the second transport means R2, and the third transport means R3.

[0059] As a result, as shown in Figure 8, the lead sheet P1 is transported to the second transport path W2 by the operation of the first transport means R1, and then transported to the second transport means R2 along the downward slope of the second transport path W2, and then transported to the third transport path W3 by the operation of the second transport means R2. When the leading edge of the lead sheet P1 is detected by the fourth sheet detection sensor SN4, a detection signal is notified from the fourth sheet detection sensor SN4 to the sheet processing control unit 210. After receiving the detection signal from the fourth sheet detection sensor SN4, the sheet processing control unit 210 calculates the timing from when the leading edge of the lead sheet P1 moves from the position of the fourth sheet detection sensor SN4 to a position corresponding to the second protrusion amount Δ2.

[0060] As shown in Figure 9, when the sheet processing control unit 210 determines that the leading edge of the preceding sheet P1 has reached a position corresponding to the second protrusion amount Δ2, it stops the rotation of the first folding means F1, the second transport means R2, and the third transport means R3, thereby stopping the transport of the preceding sheet P1.

[0061] Furthermore, even when the sheet processing control unit 210 stops transporting the preceding sheet P1, it continues to rotate the first transport means R1 in order to receive the subsequent sheet P2 that is transported from the printer unit 100.

[0062] Next, as shown in Figure 10, the sheet processing control unit 210, after receiving a detection signal from the first sheet detection sensor SN1 indicating that the leading edge of the following sheet P2 has been detected, resumes transporting the preceding sheet P1 at a timing calculated from the detection by the first sheet detection sensor SN1 while transporting the following sheet P2. The sheet processing control unit 210 then controls the rotation of the transport roller pair so that the following sheet P2 is transported overlapping the preceding sheet P1, slightly ahead of it. The timing calculated by the sheet processing control unit 210 here corresponds to the time when the leading edge of the following sheet P2 merges with the preceding sheet P1 and the following sheet P2 reaches a position corresponding to the third protrusion amount Δ3. When the leading edge of the following sheet P2 reaches the position corresponding to the third protrusion amount Δ3, the sheet processing control unit 210 resumes the rotation of the second transport means R2 and the third transport means R3. As a result, as shown in Figure 10, the transport of the preceding sheet P1, which had been stopped, is resumed.

[0063] In other words, the subsequent sheet P2 is not stopped, and the "timing" is calculated from the detection of the first sheet detection sensor SN1 while the subsequent sheet P2 is being transported. At this calculated timing, the transport of the preceding sheet P1 is resumed. Through this control, the subsequent sheet P2 is transported while overlapping with the preceding sheet P1, slightly ahead of it.

[0064] The third protrusion amount Δ3 is calculated based on the motor speeds of the 0th transport means R0 and the 3rd transport means R3, and the transport distance between the 1st sheet detection sensor SN1, the 2nd sheet detection sensor SN2, and the 4th sheet detection sensor SN4. The third protrusion amount Δ3 also serves to create the amount of offset when the leading edges of the preceding paper P1 and the following paper P2 meet just before reaching the 1st transport means R1.

[0065] Then, the leading edge of the leading edge of the preceding sheet P1 and the leading edge of the following sheet P2 merge, a sheet bundle Q is generated, and as shown in Figure 11, it passes through the nip of the first transport means R1 and is transported downstream. In this way, the following sheet P2 hits the nip of the first transport means R1 first, and then the preceding sheet P1 hits the nip of the first transport means R1. This allows the timing of the merger to be adjusted even when the third protrusion amount Δ3 is large and the sheets have not yet merged in front of the second sheet detection sensor SN2.

[0066] Subsequently, the sheet processing control unit 210 determines whether the number of sheets to be folded matches the number of sheets received, as notified by the printer unit 100. If they match, it performs the folding process described later. If they do not match, it repeats the process from Figure 8 to Figure 11, merging the next sheet P3 (the sheet P following the subsequent sheet P2) transported from the printer unit 100 with the sheet stack Q and stacking them. Whether or not the sheet P has been transported to just before the nip of the second transport means R2 can be determined, for example, from the number of drive steps of the motor that drives the first transport means R1. Therefore, a stepping motor or the like can be used as the drive motor to rotate each transport means. A DC motor can also be used if the control is based on the timing calculated by the detection of each sensor.

[0067] [Example of folding process] Next, as an example of a predetermined process in the sheet processing unit 200 according to this embodiment, the flow of the folding process will be described. Figures 12 to 15 are explanatory diagrams of the operation of folding the stack of paper Q received from upstream into thirds.

[0068] As explained in Figure 11, the merged paper stack Q is then transported by the 0th transport means R0 and the 1st transport means R1. When the leading edge of the paper stack Q enters the nip of the 1st transport means R1, the paper stack Q is transported to the 4th transport means R4. Note that in Figures 12 and onward, the paper stack Q is depicted as a single line.

[0069] The sheet processing control unit 210 drives the motor when the sheet has been transported to just before the nip of the fourth transport means R4, and rotates the first transport means R1 and the fourth transport means R4 in the direction of the arc arrow in Figure 12. The sheet is transported from the point where the leading edge of the sheet bundle Q is detected by the fifth sheet detection sensor SN5 until the leading edge of the sheet bundle Q reaches the fourth protrusion amount Δ4.

[0070] Subsequently, the sheet processing control unit 210 rotates the fourth transport means R4 (first folding means F1) in the opposite direction to the transport direction shown in Figure 8, while keeping the first transport means R1 rotating in the transport direction, so as to transport the stack of paper Q in the opposite direction (see Figure 13). This reverse rotation of the fourth transport means R4 causes the stack of paper Q to be transported in the opposite direction.

[0071] Meanwhile, as shown in Figure 14, the first transport means R1 rotates in the same direction as in the state shown in Figure 10, transporting the stack of paper Q. This causes a flex to form just before the nip of the first folding means F1. This flex enters the nip, causing the first fold to occur and the first crease to form.

[0072] The first folded stack of paper Q is transported to the second transport path W2, and is transported along the downward slope of the second transport path W2 until the leading edge of the stack of paper Q is detected by the third sheet detection sensor SN3 and the leading edge of the paper P reaches a fifth protrusion amount Δ5.

[0073] Subsequently, the sheet processing control unit 210 rotates the second transport means R2 in the opposite direction to the rotation direction shown in Figure 13, while keeping the fourth transport means R4 (first folding means F1) rotating in the transport direction. This reverse rotation of the second transport means R2 causes the paper P to be transported in the opposite direction. Meanwhile, the sheet processing control unit 210 transports the paper P by rotating the fourth transport means R4 (first folding means F1) in the direction continued from Figure 14. As a result, as shown in Figure 15, a flex is formed just before the nip of the fifth transport means R5 (second folding means F2). This flex then enters the nip, causing the second fold to be performed and the second crease to be formed.

[0074] The paper stack Q, which has undergone the second fold, passes through the fifth transport path W5 and is transported to the discharge tray 24. The fourth protrusion amount Δ4 and the fifth protrusion amount Δ5 are determined based on the total length of the paper P and the folding method set for the paper P (paper stack Q). The sheet processing control unit 210 then determines the fourth protrusion amount Δ4 and the fifth protrusion amount Δ5 based on this setting and the amount of rotation of the second transport means R2 (the number of drive steps of the drive motor).

[0075] In the case of an outward tri-fold, the first fold is made at a position corresponding to 1 / 3 of the total length of the paper P from the leading edge in the transport direction of the paper P. Then, the second fold is made at a position corresponding to 1 / 3 of the total length of the paper P on the opposite side. In the case of an inward tri-fold, the first fold is made at a position corresponding to 2 / 3 of the total length of the paper P from the leading edge in the transport direction of the paper P, and the second fold is made at 1 / 3 of the total length on the opposite side. After that, the stack of paper Q that has undergone the second fold is transported downstream via the fifth transport path W5 by the fifth transport means R5.

[0076] In the operation described above, when the stack of paper Q that has undergone the second fold is transported to the fifth transport path W5 by the fifth transport means R5, the additional folding process is executed. The additional folding process will be described in detail below.

[0077] [Folding mechanism F3] Figure 16 is an enlarged view of the refolding mechanism F3. As shown in Figure 16, the refolding mechanism F3 is equipped with a refolding roller R9 for performing a refolding process on creases formed in the paper P or paper bundle Q that have been transported to the fifth transport path W5. On the opposite side of the fifth transport path W5 from the refolding roller R9, a pressing member 251 and a biasing member 252 that bias the pressing member 251 toward the fifth transport path W5 are arranged.

[0078] When the additional folding process is performed, first, the paper P or paper bundle Q that has undergone the second fold is transported to the fifth transport path W5. Then, after the sixth sheet detection sensor SN6 detects the leading edge of the transported paper P, the sheet processing control unit 210 continues the operation of the fifth transport means R5 for a certain period of time before stopping the transport of the paper P. In other words, the transport of the paper P or paper bundle Q is stopped when a certain distance has been transported after the sixth sheet detection sensor SN6 detects the end of the paper P or paper bundle Q.

[0079] The stopping position at this time is the position where the first fold is pressed by the additional folding roller R9 and the pressing member 251. With the paper P stopped at this position, the additional folding roller R9 rotates to perform the additional folding process. As illustrated in Figure 16, the additional folding roller R9 has a projection on its outer surface, and when this projection passes the first fold by rotation, the additional folding is performed by the projection and the pressing member 251.

[0080] Whether or not to perform the additional folding process is controlled by the sheet processing control unit 210 based on attribute information of the paper P that it has received in advance from the printer control unit 110. That is, if the paper thickness information for the paper P indicates "thick paper", the sheet processing control unit 210 rotates the additional folding roller R9 included in the various loads 220 to perform the additional folding process. The number of rotations of the additional folding roller R9 may be varied according to the degree of paper thickness indicated by the thick paper information. For example, in the case of thicker paper P, the number of rotations of the additional folding roller R9 may be set to multiple times, and the number of rotations of the additional folding roller R9 may be increased each time the thickness increases.

[0081] In this embodiment, whether or not to perform an additional folding process, and the number of times to perform the additional folding process, are determined by a control program executed in the sheet processing control unit 210, which determines the stiffness of the paper P to be processed, and controls the processing content based on this determination result.

[0082] Generally, the thicker the paper P becomes, the stiffer it is, resulting in weaker (shallower) creases. As a result, the folded paper P may lose its fold at the destination after folding. In a paper bundle Q formed by bundling multiple sheets of paper P, the stiffness of the constituent sheets of paper P tends to make it more difficult to maintain the folds. Therefore, the additional folding process described above is effective from the standpoint of maintaining the fold and improving the quality of the folding process.

[0083] In this embodiment, the stiffness of the actual paper P being transported (difficulty in creasing, difficulty in maintaining creases) is detected, and the additional folding process is controlled according to the detection result.

[0084] The stiffness detection mechanism F4 for the paper P will be described using Figures 17 and 19. As illustrated in Figure 17, the stiffness detection mechanism F4 is composed of a paper deformation detection sensor SN9 and an elastic sheet 253 which is a sheet-like member having a predetermined elasticity. The stiffness detection mechanism F4 is positioned between the 0th transport means R0 and the 1st transport means R1, which is a register roller.

[0085] As shown in Figure 18, the paper P is transported by the 0th transport means R0, passes through the 1st transport path W1, and abuts against the nip of the 1st transport means R1, which is a register roller. At this time, the leading edge of the paper P is pushed toward the nip of the 1st transport path W1, causing the paper P to flex in the space of the 1st transport path W1. This corrects the skew of the paper P and corrects the deviation of the transport posture of the paper P with respect to the transport direction.

[0086] An elastic sheet 253 is provided in the first transport path W1. The elastic sheet 253 is positioned in the direction in which the paper P bends. Therefore, when the paper P is bent by the first transport means R1, the paper P is pressed against the elastic sheet 253 depending on the degree of bending. The elastic sheet 253 is made of a material having a predetermined rigidity. Therefore, the degree to which the elastic sheet 253 deforms when the paper P bends and is pressed against it will differ depending on the stiffness of the paper P.

[0087] When the paper P, which has been struck by the first transport means R1 and bent, deforms the elastic sheet 253, the paper deformation detection sensor SN9 detects this deformation. The first transport path W1 between the 0th transport means R0 and the 1st transport means R1 is shaped like an arc from the 0th transport means R0 toward the 1st transport means R1, as illustrated in Figure 17, etc. Therefore, the paper P, which has been skew-corrected in the 1st transport means R1, will move in an arc along the shape of the first transport path W1. In other words, the skew correction causes the paper P to change into an arc shape and push up the elastic sheet 253.

[0088] The paper deformation detection sensor SN9 detects the elastic sheet 253 that has been pushed up by the bent and deformed paper P. When the paper deformation detection sensor SN9 detects the elastic sheet 253, it determines that the paper P is rigid. In other words, the bending of the paper P when it is struck by the first transport means R1 and the skew is corrected is greater when the paper P is rigid. To put it another way, if the paper P is stiff, it will push up the elastic sheet 253.

[0089] On the other hand, if the paper P is not rigid, the paper P will not flex during skew correction, as illustrated in Figure 19. In this case, the elastic sheet 253 is not pushed up, so the paper deformation detection sensor SN9 does not detect the elastic sheet 253. In other words, if the paper P is not rigid, the paper deformation detection sensor SN9 does not detect the elastic sheet 253.

[0090] [Folding control flow] Next, the flow of control processing when performing the additional folding process will be explained with reference to the flowchart in Figure 20. First, when the image forming process is performed in the printer unit 100 and the paper P is discharged to the sheet processing unit 200, the printer control unit 110 notifies the sheet processing control unit 210 of information indicating the type of folding process for the paper P (folding information) and paper thickness information indicating the thickness of the paper P. The type of folding process notified is determined to be either "single-sheet folding" or "double-sheet folding" (S2001).

[0091] If the folding process is a single-sheet fold (S2001: single-sheet fold), that is, if the object to be folded is a single sheet of paper P, then it is determined whether the paper P to be processed is "thick paper" based on the paper thickness information (S2002). If the paper P to be processed is not thick paper (S2002: No), then it is determined whether the paper P to be processed is "stiff" or not based on the detection result of the paper deformation detection sensor SN9 (S2003). If the paper is not stiff (S2003: No), that is, if the paper P is not stiff and the paper deformation detection sensor SN9 did not detect the elastic sheet 253, the number of additional folds is set to "1" and the folding process is executed (S2004).

[0092] In step S2003, if the paper P to be processed is stiff (S2003:Yes), that is, if the paper P is rigid and the paper deformation detection sensor SN9 has detected the elastic sheet 253, the number of additional folds is set to "2" and the folding process is executed (S2006).

[0093] In step S2002, if the paper P to be processed is thick paper (S2002:Yes), then, based on the detection result of the paper deformation detection sensor SN9, it is determined whether the paper P to be processed is "stiff or not" (S2005). If it is not stiff (S2005:No), the number of additional folds is set to "2" and the folding process is executed (S2004). In step S2005, if it is stiff (S2005:Yes), the number of additional folds is set to "3" and the folding process is executed (S2007).

[0094] In step S2001, if the folding process involves folding two sheets of paper (S2001: two-sheet folding), that is, if the object to be folded is a stack of two sheets of paper Q, then it is determined whether the thickness of the paper P to be processed is greater than a predetermined value, based on the paper thickness information (S2101). If the paper P to be processed is not thick paper (S2101: No), then it is determined whether the amount of deflection of the paper P to be processed is greater than a predetermined amount, that is, whether it is "stiff" or not, based on the detection result of the paper deformation detection sensor SN9 (S2102). If the amount of deflection is less than a predetermined amount, that is, if it is not stiff (S2102: No), in other words, if the paper P is not stiff and the paper deformation detection sensor SN9 did not detect the elastic sheet 253, then the number of additional folds is set to "1" and the folding process is executed (S2103).

[0095] In step S2102, if the paper P to be processed is stiff (S2102: Yes), that is, if the amount of deflection is greater than a predetermined amount, in other words, if the paper P is stiff and the paper deformation detection sensor SN9 has detected the elastic sheet 253, the number of additional folds is set to "2" and the folding process is executed (S2104).

[0096] In step S2101, if the paper P to be processed is thick paper (S2101:Yes), then, based on the detection result of the paper deformation detection sensor SN9, it is determined whether the paper P to be processed is "stiff or not" (S2105). If it is not stiff (S2105:No), the number of additional folds is set to "3 times" and the folding process is executed (S2106). In step S2105, if it is stiff (S2105:Yes), the number of additional folds is set to "4 times" and the folding process is executed (S2107).

[0097] According to the folding process of this embodiment described above, the number of additional folding operations is set based on the type of folding received from the upstream device, the paper thickness information, and the information regarding the stiffness of the paper P detected by the transport means.

[0098] For example, in the setting for single-sheet folding of thick paper, two additional folds are usually performed, but if the paper is particularly stiff, the control system will increase the number of additional folds. For materials other than thick paper, one additional fold is usually performed, but if the paper is stiff, the number of additional folds will be increased. By implementing this control, it is possible to perform appropriate additional folds according to the stiffness of the paper without unnecessarily increasing the number of additional folds.

[0099] Furthermore, in the case of overlapping folds, the number of additional folds is usually equal to the number of sheets overlapped. For example, in the case of overlapping two sheets, the number of additional folds is usually increased twice, and for thick and stiff paper, the number of additional folds is increased further. However, for paper that is not thick and is not stiff, the number of additional folds is reduced to once. By implementing this control, it is possible to improve productivity and component durability without increasing the height of the paper folds.

[0100] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the technical essence, and all technical matters included in the technical concept described in the claims are subject to the present invention. The above embodiments are shown as preferred examples, but those skilled in the art can realize various modifications from the disclosed content. Such modifications are also included in the technical scope described in the claims.

[0101] [Aspects of the present invention] The contents of this invention are, for example, as follows: <1> A sheet processing device that performs folding on a sheet, Multiple conveying means for transporting the aforementioned sheet, A sheet deflection detection means for detecting the amount of deflection of the sheet in the conveying direction, A control means for controlling the operation of the conveying means to perform the folding process on the sheet being conveyed, Equipped with, The control means is When performing additional folding on the crease formed in the aforementioned folding process, the operation of the conveying means is controlled to perform the additional folding a number of times determined according to the amount of deflection and the thickness of the sheet. This is a sheet processing device characterized by the following features. <2> The sheet deflection detection means detects the deflection caused when the sheet is brought into contact with a register roller, which is one of the transport means that corrects the skew of the sheet. The aforementioned <1> This is the sheet processing device described above. <3> The control means increases the number of additional folds when the amount of deflection detected by the sheet deflection detection means is greater than a predetermined amount. The aforementioned <1> or <2> This is the sheet processing device described above. <4> The control means increases the number of additional folds when the thickness is greater than a predetermined value. The aforementioned <1> ~ <3> It is a sheet processing device described in any one of the items. <5> The control means is If the object of the folding process is a bundle of multiple sheets, the number of additional folds is set according to the number of sheets constituting the bundle. The aforementioned <1> ~ <4> It is a sheet processing device described in any one of the items. <6> The control means is If the thickness of the sheets constituting the sheet bundle is less than a predetermined value, and the amount of deflection of the sheets is less than a predetermined amount, the additional folding is performed by the number of additional folding steps for one sheet. The aforementioned <5> This is the sheet processing device described above. <7> An image forming apparatus comprising an image forming unit for forming an image on a sheet, and a sheet processing unit for performing post-processing on the sheet, The sheet processing unit is the <1> ~ <6> The image forming apparatus is characterized by being a sheet processing apparatus as described in any one of the items. <8> An image forming apparatus comprising an image forming unit that forms an image on a sheet, and the <1> ~ <6> This image forming system is characterized by being configured in conjunction with a sheet processing device described in any one of the above items. [Explanation of Symbols]

[0102] 1: Printer System 10, 10a: Printer 100, 100a: Printer unit 100b: Printer 110: Printer control unit 200, 200a: Sheet processing unit 200b: Sheet processing device 210: Sheet Processing Control Unit 220: Various loads 230: Driver 240: Various sensors 251: Pressing member 252: Biasing member 253: Elastic Sheet F3: Folding mechanism F4: Hardness detection mechanism R0: 0th conveying means R1: First conveying means R6: Sixth conveying means R9: Folding roller SN6: 6th sheet detection sensor SN9: Paper deformation detection sensor [Prior art documents] [Patent Documents]

[0103] [Patent Document 1] Japanese Patent Publication No. 2008-105317

Claims

1. A sheet processing device that performs folding on a sheet, Multiple conveying means for transporting the aforementioned sheet, A sheet deflection detection means for detecting the amount of deflection of the sheet in the conveying direction, A control means for controlling the operation of the conveying means to perform the folding process on the sheet being conveyed, Equipped with, The control means is When performing additional folding on the crease formed in the aforementioned folding process, the operation of the conveying means is controlled to perform the additional folding a number of times determined according to the amount of deflection and the thickness of the sheet. A sheet processing apparatus characterized by the following:

2. The sheet deflection detection means detects the deflection caused when the sheet is brought into contact with a register roller, which is one of the transport means that corrects the skew of the sheet. The sheet processing apparatus according to claim 1.

3. The control means increases the number of additional folds when the amount of deflection detected by the sheet deflection detection means is greater than a predetermined amount. The sheet processing apparatus according to claim 1.

4. The control means increases the number of additional folds when the thickness is greater than a predetermined value. The sheet processing apparatus according to claim 1.

5. The control means is If the object of the folding process is a bundle of multiple sheets, the number of additional folds is set according to the number of sheets constituting the bundle. The sheet processing apparatus according to claim 1.

6. The control means is If the thickness of the sheets constituting the sheet bundle is less than a predetermined value, and the amount of deflection of the sheets is less than a predetermined amount, the additional folding is performed by the number of additional folding steps for one sheet. The sheet processing apparatus according to claim 5.

7. An image forming apparatus comprising an image forming unit for forming an image on a sheet, and a sheet processing unit for performing post-processing on the sheet, The image forming apparatus is characterized in that the sheet processing unit is the sheet processing unit according to any one of claims 1 to 6.

8. An image forming system characterized by being configured by connecting an image forming apparatus having an image forming unit for forming an image on a sheet and a sheet processing apparatus according to any one of claims 1 to 6.

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