Conveyance device and image forming system

Abstract

To provide a conveying device capable of improving skew detection accuracy by varying a skew detection interval according to the size of a medium.SOLUTION: The sheet processing apparatus includes a transport unit that transports a sheet-shaped medium, a skew detection unit that detects a skew amount of the medium transported in a first direction, a skew detection moving unit that moves the skew detection unit in a second direction orthogonal to the first direction, and a control unit that controls operations of the transport unit, the skew detection unit, and the skew detection moving unit.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a conveying device and an image forming system. [Background technology]

[0002] Conveying devices that convey sheet-like media are known. Also known are sheet processing devices that include a conveying device and perform predetermined processing on media, and image forming systems that allow a sheet processing device with a conveying device to be installed inside a drum so that predetermined processing can be performed on media on which an image has been formed.

[0003] When a sheet-like medium is transported in a transport device, the medium may become skewed relative to the transport direction. For the purpose of skew correction, a configuration has been disclosed in which an appropriate correction amount is calculated from the skew amount to perform skew correction efficiently (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration disclosed in Patent Document 1, skew detection is performed regardless of the size of the medium being transported. Therefore, when the size of the medium is relatively large or small, there is a problem in that the accuracy of skew detection for media of various sizes decreases when skew detection is based on a predetermined medium size.

[0005] An object of the present invention is to provide a transport device that can increase the accuracy of skew detection by varying the skew detection interval depending on the size of the medium. [Means for solving the problem]

[0006] In order to solve the above technical problems, one aspect of the present invention comprises a transport means for transporting a sheet-like medium in a first direction, a skew detection means for detecting the amount of skew of the medium transported in the first direction, a skew detection moving means for moving the skew detection means in a second direction perpendicular to the first direction, and a control means for controlling the operation of the transport means, the skew detection means, and the skew detection moving means, wherein the control means controls the skew detection moving means according to the size of the medium and varies the detection interval at which the skew detection means detects the edge of the medium in the second direction. [Effects of the Invention]

[0007] According to the present invention, the skew detection interval can be varied depending on the size of the medium, thereby improving the accuracy of skew detection. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an external view showing an example of a printing system as an embodiment of an image forming apparatus according to the present invention. [Figure 2] FIG. 10 is an external view showing another example of a printing system as an embodiment of an image forming apparatus according to the present invention. [Figure 3] FIG. 1 is a functional block diagram of an example of a printing system according to an embodiment of the present invention. [Figure 4] FIG. 10 is a functional block diagram of another example of a printing system according to the embodiment. [Figure 5] FIG. 2 is a control configuration diagram of a sheet processing unit according to the embodiment. [Figure 6] FIG. 2 is a cross-sectional view of the sheet processing unit according to the embodiment. [Figure 7] 5A to 5C are diagrams illustrating an example of an operation process of the sheet processing unit according to the embodiment. [Figure 8] 5A to 5C are diagrams illustrating an example of an operation process of the sheet processing unit according to the embodiment. [Figure 9] 5A to 5C are diagrams illustrating an example of an operation process of the sheet processing unit according to the embodiment. [Figure 10] 5A to 5C are diagrams illustrating an example of an operation process of the sheet processing unit according to the embodiment. [Figure 11] 5A to 5C are diagrams illustrating an example of an operation process of the sheet processing unit according to the embodiment. [Figure 12] FIG. 2 is a cross-sectional view of the lateral registration detection device according to the embodiment. [Figure 13] 5A and 5B are diagrams for explaining an outline of a skew detection operation according to the present embodiment. [Figure 14] FIG. 4 is a table data configuration diagram showing an example of sheet information according to the embodiment. [Figure 15] 5A and 5B are diagrams for explaining sampling errors in the skew detection operation according to the embodiment. [Figure 16] 5A and 5B are diagrams for explaining the amount of skew in the skew detection operation according to the embodiment; [Figure 17] 5A to 5C are diagrams illustrating an example of an operation process of the binding processing unit according to the embodiment. [Figure 18] 5A to 5C are diagrams illustrating an example of an operation process of the binding processing unit according to the embodiment. [Figure 19] 5A to 5C are diagrams illustrating an example of an operation process of the binding processing unit according to the embodiment. [Figure 20] 5A to 5C are diagrams illustrating an example of an operation process of the binding processing unit according to the embodiment. [Figure 21] 5A to 5C are diagrams illustrating an example of an operation process of the binding processing unit according to the embodiment. [Figure 22] 6A to 6C are diagrams illustrating an example of a skew correction operation in the binding processing unit according to the embodiment. [Figure 23] FIG. 2 is a schematic diagram illustrating a connection between the sheet processing unit and an external device according to the embodiment. [Figure 24] 5A to 5C are diagrams illustrating a connecting operation process between the sheet processing unit and an external device according to the embodiment. [Figure 25] FIG. 2 is a schematic diagram of a punching unit according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a conveying device and an image forming system according to the present invention will be described with reference to the drawings. Note that, in the following, the conveying device according to the present invention is exemplified as being provided in a sheet processing unit 100 as an embodiment of a sheet processing apparatus. The conveying device has a function of moving a sheet S, which is a sheet-like medium, in a predetermined direction along a conveying path. The sheet processing unit 100 has a function of performing a predetermined process on the sheet S moved by the conveying device.

[0010] [Embodiment of Image Forming System] 1 is an external view of a printing system 1 as an embodiment of an image forming system according to the present invention. The printing system 1 is an apparatus equipped with an image forming function that forms an image on a sheet S (typically, paper) as a sheet-like medium, and a sheet processing function that performs predetermined sheet processing (post-processing) on ​​the sheet S on which the image has been recorded.

[0011] As shown in Fig. 1, the printing system 1 mainly comprises a housing 31 and an image forming unit 32 inside the housing 31. The housing 31 is a box-shaped member having an internal space for accommodating the components of the printing system 1. The housing 31 also has an internal space 33 that is accessible from outside the printing system 1. The internal space 33 is located, for example, slightly above the center of the housing 31 in the vertical direction. The internal space 33 is exposed to the outside by cutting out an outer wall of the housing 31.

[0012] Furthermore, a sheet processing unit 100 as an embodiment of a sheet processing device can be attached to the internal space 33. The sheet processing unit 100 illustrated in FIG. 1 is configured to include a binding processing unit 110 that mainly performs a "binding process" of bundling and binding sheets S, and a hole punching unit 120 that performs a "punching process" of punching holes in the sheets S. The sheet processing unit 100 can also be attached in a form in which the binding processing unit 110 and the hole punching unit 120 are separated. For example, as illustrated in FIG. 2, it is also possible to attach only the binding processing unit 110.

[0013] In the following description, an example will be given in which the binding unit 110 and the punch hole forming unit 120 are integrally attached as the sheet processing unit 100.

[0014] Returning to FIG. 1, the image forming means 32 forms an image on a sheet S that has been picked up from a sheet storage tray and conveyed by a conveying means made up of a pair of conveying rollers. From the image forming means 32, the sheet S is conveyed in this order to a punch hole punching unit 120 and a binding processing unit 110. The image forming means 32 may be of an inkjet type that forms an image using ink, or may be of an electrophotographic type that forms an image using toner. The configuration of the image forming means 32 is already well known, so a detailed description thereof will be omitted.

[0015] The punch hole punching unit 120 is attached to the internal space 33 of the printing system 1 downstream of the image forming means 32 and upstream of the binding processing unit 110 on the conveyance path of the sheet S from the image forming means 32 to the sheet processing unit 100 (the path indicated by the dashed arrow in FIG. 1). That is, the sheet S on which an image has been formed by the image forming means 32 is first conveyed to the punch hole punching unit 120, where a predetermined punch hole forming process is performed. Thereafter, the sheet S is conveyed to the binding processing unit 110, where a binding process is performed to bind a sheet bundle Sb formed by bundling multiple sheets S.

[0016] In the following description, both the printing system 1 and the sheet processing unit 100 are assumed to be equipped with a transport means consisting of a pair of transport rollers, a drive source that drives the pair of transport rollers, and a control unit that controls the operation of the drive source, as a configuration for transporting (moving) the sheet S.

[0017] The punch hole punching unit 120 is configured to be detachable from the printing system 1. When the punch hole punching unit 120 is detached, as shown in Fig. 2, the sheets S on which images have been formed by the image forming means 32 are directly handed over to the binding processing unit 110 for binding processing. Note that another processing unit that performs any processing on the sheets S can be attached to the position in the internal space 33 from which the punch hole punching unit 120 has been detached.

[0018] [Embodiment of control configuration] Fig. 3 shows an example of the control configuration of the printing system 1 when the punch hole punching unit 120 is installed (see Fig. 1). In Fig. 3 as well, the transport path of the sheet S (flow of the sheet S) formed by the transport means is represented by dashed arrows, and the path (signal flow) of the communication signal (control signal) is represented by solid arrows.

[0019] The printing system 1 includes a display unit 301 that notifies the user of the status of various devices and operation details, an operation unit 302 that the user uses to set the mode, number of copies, etc., and a paper feed unit 303 that stocks sheets S and separates and feeds them one by one. The printing system 1 also includes an image creation unit 304 that forms a latent image on a photoreceptor (not shown in Fig. 3) and transfers the image to the sheet S, and a fixing unit 305 that fixes the image transferred to the sheet S. The printing system 1 also includes an image formation control unit 306 that controls the operation of each of the above units.

[0020] The binding processing unit 110 receives a processing instruction from the image formation control unit 306 of the printing system 1 via a communication line 307 to the binding processing control unit 112, and performs a specified process on the specified sheet S in the binding processing unit 111. The punching processing unit 121 is notified of specified information on the process content for the sheet S from the image formation control unit 306 via the binding processing unit 111.

[0021] The image forming control units 306 and binding process control units 112 are connected to each other via a communication line 307, enabling the exchange of information. This allows the exchange of information regarding the operation mode, sheet size, timing, etc., enabling the system to operate.

[0022] The punch hole punching unit 120 receives processing instructions from the image formation control unit 306 of the printing system 1 to the binding process control unit 112 via a communication line 307, and the binding process control unit 112 sends instructions to the punching process control unit 122 via a communication line 103. The punching process control unit 122 controls the punching processing unit 121 to execute the instructed punching process.

[0023] FIG. 4 is a diagram illustrating an example of the control configuration of the printing system 1 including the sheet-processing unit 100, with the hole punching unit 120 removed.

[0024] Like the printing system 1 shown in FIG. 3, the printing system 1 shown in FIG. 4 also includes a display unit 301, an operation unit 302, and a paper feed unit 303, as well as an image forming unit 304 and an image formation control unit 306.

[0025] In the printing system 1 shown in Figure 4, the image formation control unit 306 issues a processing instruction to the binding processing control unit 112 via the communication line 307, and the binding post-processing unit 111 performs the specified processing on the specified sheet S.

[0026] That is, each of the linked image forming control units 306 and binding process control units 112 is connected by a communication line 307, enabling the exchange of information. This allows the exchange of information on the operation mode, sheet size, timing, etc., enabling the system to operate.

[0027] [Hardware configuration of printing system 1] Next, the hardware configuration of the binding processing unit 110 included in the printing system 1 will be described with reference to Fig. 5. As shown in the figure, the sheet processing unit 100 has a CPU 150 as a controller, and is connected to multiple motors that serve as power sources for the operation of each mechanism via an I / F (interface) 170. The CPU 150 is a computing means, and controls the operation of the entire binding processing unit 110.

[0028] The CPU 150 in the binding processing unit 110 is connected to the image formation control unit 306 of the printing system 1 via the I / F 170, and controls the binding processing unit 110 in response to processing signals from the printing system 1. The binding processing unit 110 is also an optional device, and therefore has a detachable hardware configuration.

[0029] Each motor is equipped with an encoder that can detect the motor drive amount in pulse count, and can be stopped at a position of a specific drive amount starting from a specific timing. Also, based on the timing when the sensor on the transport path is turned ON or OFF, the drive amount of each motor is calculated based on the encoder pulse, and the position of the edge of the transported sheet S can be detected based on that drive amount.

[0030] As illustrated in FIG. 5, the binding processing unit 110 is connected to a conveying motor 151, a discharge motor 152, a jogger front drive motor 153, a jogger rear drive motor 154, a staple drive motor 155, a conveying sensor 156, a discharge sensor 157, a binding unit moving motor 158, and an entrance sensor 24 via an I / F 170.

[0031] The punching process control unit 122 is also connected to the punching motor 161 , punch movement motor 162 , punching device adjustment motor 218 , lateral registration sensor 211 a , and lateral registration sensor movement motor 216 via the I / F 170 .

[0032] [Conveyance path configuration of sheet processing unit 100] Next, the configuration of a conveying path for a sheet S provided in a sheet processing unit 100 as an embodiment of a sheet processing apparatus according to the present invention will be described with reference to Fig. 6. Fig. 6 shows a cross-sectional view of the conveying path provided in the sheet processing unit 100. The sheet processing unit 100 can be set to a plurality of operation modes, and operation control is performed by a binding process control unit 112 based on the set operation mode.

[0033] The sheet processing unit 100 according to this embodiment will be described on the assumption that the sheet processing unit 100 is mounted on the printing system 1 already described, and that it is a combination of a binding processing unit 110 and a punch hole punching unit 120.

[0034] The sheet S, on which an image has been formed by the image forming means 32, is conveyed into the punch hole punching unit 120 via the conveying means. The conveying direction of the sheet S at this time is referred to as the first direction. The sheet S conveyed in the first direction passes through the punch hole punching unit 120 and is delivered to the entrance rollers 11 of the binding processing unit 110. The punch hole punching unit 120 is provided with a lateral registration detection device 211, which will be described later. The lateral registration detection device 211 has a mechanism that is movable in a second direction that is perpendicular to the first direction. If the first direction is the length direction of the sheet S, then the second direction corresponds to the width direction of the sheet S. In the following description, the term "length direction" may be used instead of the first direction, and the term "width direction" may be used instead of the second direction.

[0035] As the sheet S passes through the punch hole punching unit 120, a lateral registration detection device 211 detects the edge in the second direction (edge ​​in the width direction) of the sheet S, and moves a punching device 212 (described later) to match the position of the detected edge in the width direction. That is, the punch hole punching unit 120 includes a punching device 212 that moves the position where punch holes are formed in accordance with the detection result of the lateral registration detection device 211. Although not shown, the punch hole punching unit 120 also includes a conveying means consisting of a pair of conveying rollers, and this conveying means stops the sheet S at a position where holes are to be punched. Then, punch pins 213 in the punching device 212 form punch holes in the sheet S whose conveying has stopped. Punch waste generated during punching falls into a punch waste hopper 214 and accumulates therein. After punching, the sheet S is conveyed again, and further processing in the binding processing unit 110 is performed.

[0036] As shown in Fig. 6, the punch hole punching unit 120 mainly includes a lateral registration detection device 211 and a punching device 212. The lateral registration detection device 211 moves in the width direction to detect the width direction edge of the sheet S. The punching device 212 moves in the width direction to align the punching pins 213 according to the detected position of the width direction edge of the sheet S. The punching pins 213 are members that form punch holes by penetrating the sheet S. The punching dust hopper 214 accumulates punching dust created when the punching unit 120 punches holes.

[0037] Although not all of these components are shown in FIG. 6, the punch hole forming unit 120 also includes a lateral registration sensor drive belt punch hopper 215, a lateral registration sensor movement motor 216, a lateral registration sensor movement belt 217, and a punching device adjustment motor 218.

[0038] The lateral registration sensor drive belt punch hopper 215 accumulates punch waste generated when punch holes are punched by the punch hole punching unit 120. The lateral registration sensor movement motor 216 is a drive source that moves the lateral registration detection device 211 in the width direction. The lateral registration sensor movement belt 217 is a belt that transmits the drive force of the lateral registration sensor movement motor 216 to the lateral registration detection device 211. The punch hole punching device adjustment motor 218 is a drive source that moves the position of the punch pins 213 in the punch hole punching unit 120 to change the position of the punch pins 213 relative to the sheet S.

[0039] The binding processing unit 110 can be selectively set to either a shift discharge mode or a staple binding mode. In this embodiment, the binding processing unit 110 is exemplified as being equipped with a staple binding unit 19. However, it may be equipped with a pressure binding unit that performs pressure binding without using staples, or it may be equipped with both.

[0040] When the binding processing unit 110 is in the shift discharge mode, the inlet sensor 24 detects the sheet S transported from the printing system 1, and then the inlet rollers 11 constituting the transport means rotate to receive the sheet S. Then, the sheet S is transported to the discharge rollers 16 by the inlet rollers 11, transport rollers 12, and shift rollers 13, and is discharged onto the discharge tray 20. The inlet rollers 11, transport rollers 12, shift rollers 13, and discharge rollers 16 constitute a first transport means. In other words, when the sheet S is transported from the inlet rollers 11 toward the discharge rollers 16, the transport direction corresponds to the first direction.

[0041] When the binding processing unit 110 is in staple binding mode, the entrance rollers 11 receive the sheet S conveyed from the printing system 1, and the sheet S is conveyed in the first direction to the shift rollers 13. When the sheet S leaves the shift rollers 13, the tapping rollers 15 are driven to place the sheet S on a stacking tray 17, which serves as an internal tray. The tapping rollers 15 and the return rollers 14 then operate to convey the sheet S in a third direction, which is the opposite direction to the first direction. The third direction is a conveyance toward a reference fence 18 for aligning the edge of the sheet S, and corresponds to a "switchback conveyance" because it is a conveyance opposite to the first direction. The tapping rollers 15 and the return rollers 14 constitute a switchback conveyance means for conveying the sheet S in the third direction.

[0042] In the staple binding mode, the above-described conveying operation of the sheets S in the third direction (the operation of conveying the sheets S along the stacking tray 17 to the reference fence 18) is repeated until the number of sheets to be stapled is reached. Then, when the final sheet S is conveyed to the reference fence 18, the edge of the stack of sheets S (sheet stack Sb) is stapled by the staple binding unit 19. The stapled sheet stack Sb is conveyed in the first direction by discharge rollers 16 constituting the conveying means and discharged to the discharge tray 20.

[0043] The sheet S or the sheet stack Sb discharged onto the discharge tray 20 is aligned by abutting the end of the sheet S or the sheet stack Sb against the end fence 21.

[0044] [First embodiment of sheet processing unit 100] Next, a description will be given of an embodiment of the skew detection operation executed in the sheet processing unit 100. Fig. 7 illustrates a state before the sheet S is inserted into the punch hole punching unit 120. In this state, the lateral registration detection device 211 is waiting at the center of the conveyance path.

[0045] 8, when the sheet S is inserted into the punch hole punching unit 120, the lateral registration sensor 211a mounted on the lateral registration detection device 211 moves from the center position of the conveyance path in a direction perpendicular to the conveyance direction of the sheet S (second direction). The position of the lateral registration sensor 211a at this time is set according to the size of the sheet S, and is a position equivalent to 1 / 4 of the width dimension of the sheet S. The lateral registration detection device 211 waits at a standby position until it detects the edge of the sheet S in the conveyance direction.

[0046] The standby position of the lateral registration detection device 211 is determined by the size of the sheet S, more specifically, the width dimension of the sheet S. Information regarding the size of the sheet S (sheet information) is assumed to be notified in advance to the binding process control unit 112 from the image formation control unit 306. That is, the sheet processing unit 100 identifies in advance the width dimension of the sheet S to be inserted into the punch hole punching unit 120, and the punching process control unit 122 controls the movement of the lateral registration detection device 211 based on the sheet information as medium information.

[0047] The lateral registration detection device 211 uses a lateral registration sensor 211a to detect that the sheet S has been conveyed and to detect the leading edge and trailing edge of the sheet S. Therefore, it is necessary to quickly move to a standby position after the sheet S has been conveyed and before the lateral registration sensor 211a detects the edge of the leading portion in the conveyance direction of the sheet S. Therefore, before detecting the conveyance of the sheet S, the device moves to a position shifted by a distance of ¼ of the width of the sheet S from the center of the conveyance path of the sheet S at the time when the sheet information is acquired, and waits until the sheet S is detected.

[0048] 8, after the sheet S is conveyed and the lateral registration sensor 211a of the lateral registration detection device 211 detects the leading edge of the sheet S, the lateral registration sensor 211a is moved to a position for detecting the edge in the width direction of the conveyance direction of the sheet S. That is, the lateral registration detection device 211 is moved in the second direction.

[0049] 9, the lateral registration detection device 211 moves in the second direction to detect the widthwise edge of the sheet S. The widthwise edge to be detected at this time is a position (near the leading edge) corresponding to the vicinity of the leading edge in the conveyance direction of the sheet S. In this detection operation, the lateral registration detection device 211 detects the widthwise edge while moving relative to the sheet S.

[0050] 10, the lateral registration detection device 211 detects the width direction edge near the leading end of the sheet S, and then moves to a retracted position. The reason why the lateral registration sensor 211a is retracted after detecting the width direction edge near the leading end is to be able to deal with any skew direction by placing the sheet S in a position where it will not detect the sheet S until the width direction edge near the trailing end of the sheet S is detected.

[0051] 11, in order to detect the width direction edge of the sheet S in the vicinity of the rear end, which is the rear end of the sheet S in the conveying direction, the binding process control unit 112 manages the conveyance amount after detecting the width direction edge near the leading end. Then, in the binding process control unit 112, the lateral registration detection device 211 for detecting the width direction edge near the trailing end is moved in a second direction in accordance with size information of the sheet S, and the width direction edge is detected.

[0052] As described above, the lateral registration detection device 211 is moved to the standby position in advance in accordance with the conveyance timing of the sheet S, and the widthwise edge of the sheet S is detected near the leading edge. At this time, the lateral registration detection device 211 is moved in the second direction to detect the widthwise edge of the sheet S. Then, after detecting the widthwise edge near the leading edge, the lateral registration detection device 211 is temporarily moved to a retracted position and starts moving from the standby position in accordance with the conveyance amount of the sheet S to detect the widthwise edge near the trailing edge. Then, the lateral registration detection device 211 is moved in the second direction to detect the widthwise edge near the trailing edge of the sheet S, and the widthwise edge of the sheet S is detected again.

[0053] By the above detection process, the position in the second direction of the width direction end of the sheet S being transported in the first direction can be obtained at two locations, near the front and rear of the transport direction of the sheet S. Note that the number of locations is not limited to two, and the movement and detection operation of the lateral registration detection device 211 in the second direction may be repeated a further number of times (multiple times) to detect the width direction end of the sheet S.

[0054] [Embodiment of the lateral registration detection device 211] 12 is a cross-sectional view of the lateral registration detection device 211 as a skew detection means, viewed in the conveyance direction of the sheet S. As shown in Fig. 12, the lateral registration detection device 211 is held so as to be movable in the second direction by a lateral registration sensor movement motor 216 and a lateral registration sensor movement belt 217 as a skew detection movement means. The movement direction and movement amount of the lateral registration detection device 211 are instructed by the binding process control unit 112.

[0055] "Skew detection timing explanation" 13 is a diagram illustrating an outline of the execution timing of the skew detection process that is set according to the size of the sheet S. For example, as illustrated in FIG. 13, the explanation will be given using a first sheet S1 that is assumed to have a standard size and a second sheet S2 that is larger than the first sheet S1.

[0056] As already explained, the lateral registration detection device 211 detects the widthwise edge near the leading end in accordance with the size of the sheet S (sheet information), and then moves to detect the widthwise edge near the trailing end based on the position of the trailing end of the sheet S, which is determined in accordance with the size of the sheet S. That is, in the edge detection process (skew detection) of the sheet S by the lateral registration detection device 211, the edge detection timing is variable depending on the size of the sheet S.

[0057] 7 to 11, the lateral registration detection device 211 has a single lateral registration sensor 211a for detecting the edge of the sheet S. In Fig. 13, in order to explain the edge detection timing, the lateral registration sensors 211a are schematically drawn near the leading end and the trailing end.

[0058] The detection of the width direction edge for skew detection is performed based on the sampling period of the lateral registration sensor 211a, and therefore includes a deviation from the actual position of the edge of the sheet S. Therefore, the detection result of the width direction edge of the sheet S by the lateral registration detection device 211 includes a sampling error due to the conveyance speed of the sheet S and the sampling of the lateral registration sensor 211a (see FIG. 15).

[0059] However, the sampling error remains the same regardless of the position in the conveying direction where the lateral registration sensor 211a detects the width direction edge of the sheet S. Therefore, the accuracy of the skew amount can be improved by widening the skew detection timing, as shown in the correlation data between the sheet information and the skew detection timing illustrated in FIG.

[0060] Furthermore, the timing of detecting the width direction edge of the sheet S for skew detection is based on the table data shown in Fig. 14, and a correction value according to the paper thickness is added by taking into account the slip amount of the sheet S specified by the sheet information. However, since the slip amount increases as the paper thickness increases, the relationship is such that the first paper thickness correction value is greater than the second paper thickness correction value.

[0061] The detection of the amount of skew will be described with reference to FIG. 16. In FIG. 16, the detection interval of the width direction edge of the sheet S by the lateral registration detection device 211 is illustrated as a transport amount L1. The transport amount L1 corresponds to the detection interval from when the lateral registration sensor 211a detects the width direction edge near the leading edge of the sheet S until when the lateral registration sensor 211a detects the width direction edge near the trailing edge. Therefore, if the length of the sheet S in the transport direction (sheet length) changes, the detection interval changes. The width direction edge near the leading edge and the width direction edge near the trailing edge of the sheet S are detected while the sheet S is being transported, and the amount of skew of the sheet S during transport can be detected based on the difference between these positions.

[0062] Since the lateral registration detection device 211 does not move in the conveying direction (first direction) of the sheet S, the widthwise skew amount L2 of the sheet S can be calculated based on the conveying amount L1 of the sheet S, the conveying speed of the sheet S, and the timing at which the widthwise end is detected.

[0063] Then, based on the transport amount L1 and the skew amount L2, the amount of inclination θ of the sheet S with respect to the transport direction (first direction) can be calculated. Here, the amount of inclination θ is calculated by the following equation: -1 (L2 / L1)". This is defined as formula (1). Furthermore, the transport direction skew amount L4 is calculated using "width dimension L3 sin θ of sheet S". This is defined as formula (2). Based on the above formulas (1) and (2), the transport direction skew amount L4 of sheet S can be calculated. Note that even if the direction in which sheet S skews is different, the skew amount can be calculated based on the same formulas (1) and (2).

[0064] [Staple binding mode operation process] Next, with reference to several drawings, a description will be given of the operation steps of the staple binding mode among the conveyance process and binding process of the sheet S in the binding process unit 110. First, FIG. 17 shows a state in which the sheet S is received by the binding process unit 110.

[0065] Subsequently, as shown in FIG. 18, in the staple binding mode, the sheet S is conveyed without being shifted, so the discharge driven roller 16b remains at the nip pressure release position, and the sheet S is conveyed in the first direction.

[0066] 19, the sheet S whose rear end has come off the shift roller 13 falls by its own weight onto the stacking tray 17 serving as an internal tray. Then, the striking roller 15 comes into contact with the sheet S placed on the stacking tray 17 and conveys the sheet S in the second direction. As a result, the sheet S is conveyed in a switchback manner toward the reference fence 18 while still placed on the stacking tray 17.

[0067] 20, the sheet S is conveyed by switchback conveyance by the striking rollers 15 and the return rollers 14 until the end of the sheet S (the end corresponding to the leading edge in conveyance in the third direction) strikes against a reference fence 18 serving as conveyance direction alignment means. After the end of the sheet S strikes against the reference fence 18, the side (width direction) end of the sheet S strikes against a front jogger fence 22a and a rear jogger fence 22b (hereinafter, these may be collectively referred to as "jogger fences 22") serving as width direction alignment means, thereby sandwiching the sheet S. By this operation, the width direction end of the sheets S stacked on the stacking tray 17 is aligned.

[0068] 17 to 20 are repeatedly performed, resulting in a state in which a plurality of sheets S are stacked on the stacking tray 17. Here, the number of repetitions corresponds to the number of sheets S for forming the sheet bundle Sb. Next, as shown in FIG. 21, the sheets S are stacked on the stacking tray 17, and then a portion (a portion of the end portion) of the sheet bundle Sb is stapled using the staple binding unit 19. When stapling is performed, the discharge driven roller 16b moves to the nip position. Then, the sheet bundle Sb is discharged to the discharge tray 20 by the discharge roller 16.

[0069] [Embodiment of Skew Correction in Sheet Processing Unit 100] In the binding process by the binding process unit 110 described above, an embodiment of conveyance control based on the conveyance direction skew amount L4 calculated using the lateral registration detection device 211 will be described. Fig. 22 illustrates a case where the sheet S is in a skewed state and reaches the state shown in Fig. 20.

[0070] If the sheet S is not skewed, the sheet S can be transported in the third direction until it reaches the reference fence 18, as already explained in Fig. 20. However, if the sheet S is skewed, as shown in Fig. 22, if the transport amount in the third direction is set to a default value based on the size of the sheet S, the sheet S will reach the reference fence 18 in a skewed state.

[0071] Even if the skewed sheet S reaches the reference fence 18, the end of the sheet S in the conveying direction cannot be aligned, resulting in a malfunction of the binding process.

[0072] Therefore, the transport amount by the striking rollers 15 and the return rollers 14 is corrected in accordance with the magnitude of the calculated transport direction skew amount L4, and transport control in the third direction is executed. This corrects the skew of the sheets S, and the transport direction end of each sheet S is aligned with the reference fence 18 as illustrated in FIG. 22, allowing the binding process to be performed normally.

[0073] [Second embodiment of the sheet processing unit 100] The sheet processing unit 100 may be configured to be connected to an image forming apparatus 300 as an external device, and to acquire the transport timing of the sheet S from the image forming apparatus 300. Fig. 23 shows an example of the sheet processing unit 100 connected to the image forming apparatus 300 as an external device. The image forming apparatus 300 is provided with an image forming apparatus exit roller 318 and an image forming apparatus exit sensor 319.

[0074] 12, the image forming apparatus outlet sensor 319 may be used to detect the feeding of the sheet S into the punch hole punching unit 120, instead of using the lateral registration detection device 211. Also, the feeding and unfeeding of the sheet S may be performed using the inlet sensor 24 provided in the binding processing unit 110.

[0075] When detecting the introduction of the sheet S using the image forming apparatus exit sensor 319 arranged upstream of the lateral registration detection device 211, the widthwise edge near the leading edge can be detected more quickly than when detecting the introduction of the sheet S using the lateral registration sensor 211a of the lateral registration detection device 211. In other words, since the lateral registration sensor 211a can be moved toward the widthwise edge without waiting for the leading edge of the sheet S to be detected at a position corresponding to 1 / 4 of the width dimension of the sheet S, the widthwise edge of the sheet S can be detected more accurately and the amount of skew can be calculated more accurately even when the conveyance speed of the sheet S is high.

[0076] [Embodiment of the punch hole punching unit 120] Next, an embodiment of the punch hole punching unit 120 as a punching means will be described with reference to Figure 23. The punch hole punching unit 120 performs punching processing on each sheet S every time a sheet S is conveyed. If punching processing is performed while the sheet S is in a skewed state, the holes will be in incorrect positions.

[0077] Therefore, the horizontal registration detection device 211 is disposed upstream of the punch hole punching unit 120, and a conveying direction skew amount L4 for the sheet S conveyed toward the punch hole punching unit 120 is calculated in advance. Depending on the conveying direction skew amount L4, one side of the punching device 212 is moved in the first direction or the third direction using the punching device adjustment motor 218. This allows skew correction to be performed even during haunch punching, allowing punch holes to be opened.

[0078] According to the sheet processing unit 100 described above, by detecting skew in accordance with the size of the sheet S, it is possible to maintain the accuracy of skew detection even for a large-sized sheet S.

[0079] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

[0080] The contents of the present invention are as follows, for example. <1> a conveying means for conveying a sheet-like medium; a skew detection unit that detects the amount of skew of the medium transported in a first direction; a skew detection moving means for moving the skew detection means in a second direction perpendicular to the first direction; a control means for controlling the operations of the transport means, the skew detection means, and the skew detection moving means; Equipped with the control means controls the skew detection movement means in accordance with the size of the medium, and varies the detection interval at which the skew detection means detects the edge of the medium in the second direction. The transport device is characterized by the above. <2> The control means a standby position for the skew detection means to detect the edge in the second direction is varied depending on the size of the medium; The aforementioned <1> 2 is a conveying device according to the first embodiment. <3> The control means During the detection interval between when the skew detection means detects the edge in the second direction near the leading end of the medium in the first direction and when the skew detection means detects the edge in the second direction near the trailing end of the medium in the first direction, moving the medium to a position where the skew detection means does not detect it; The aforementioned <1> or the above <2> 2 is a conveying device according to the first embodiment. <4> The control means setting the detection interval based on medium information relating to the size or thickness of the medium; The aforementioned <3> 2 is a conveying device according to the first embodiment. <5> the skew detection means detects the leading edge of the medium in the first direction before detecting the end in the second direction. The aforementioned <1> and the above <4> The conveying device is described in any one of the above. <6> the transport means includes a first transport means that transports the medium in the first direction and a switchback transport means that transports the medium in a direction opposite to the first direction, the control means also controls the operation of the first transport means and the switchback transport means, and sets the transport amount of the medium by the switchback transport means in accordance with the amount of skew detected by the skew detection means. The aforementioned <1> and the above <5> The conveying device is described in any one of the above. <7> the control means moves the skew detection means to a position where the edge of the medium in the second direction near the leading end of the medium in the first direction can be detected based on a transport timing of the medium notified from an external device; The aforementioned <1> and above <6> The conveying device is described in any one of the above. <8> The medium may further include a punching means that is held rotatably about an axis in the second direction, and the punching means is configured to perform a perforation process on the medium. the control means varies the angle of rotation of the punching means in accordance with the amount of skew. The aforementioned <1> and the above <7> The conveying device is described in any one of the above. <9> The housing and an image forming unit housed in the housing and forming an image on a sheet-like medium; a conveying mechanism for conveying the medium on which an image is formed by the image forming means, the conveying mechanism being detachably supported by the housing; <1> and the above <8> a conveying device according to any one of the above items; The image forming system is characterized by comprising: [Explanation of symbols]

[0081] 1: Printing system 100: Sheet processing unit 110: Binding processing unit 120: Hole punching unit 121: Punching processing section 122: Punching processing control section 161: Punching motor 162: Punch movement motor 211: Horizontal registration detection device 211a: Horizontal registration sensor 212: Punching device 213: Punch perforation pin 214: Punch waste hopper 215: Horizontal registration sensor driven belt punch hopper 216: Horizontal registration sensor movement motor 217: Horizontal registration sensor moving belt 218: Punching device adjustment motor 318: Image forming device exit roller 319: Image forming device exit sensor [Prior art documents] [Patent documents]

[0082] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-272021

Claims

1. a conveying means for conveying a sheet-like medium; a skew detection unit that detects the amount of skew of the medium transported in a first direction; a skew detection moving means for moving the skew detection means in a second direction perpendicular to the first direction; a control means for controlling the operations of the transport means, the skew detection means, and the skew detection moving means; Equipped with the control means controls the skew detection movement means in accordance with the size of the medium, and varies the detection interval at which the skew detection means detects the edge of the medium in the second direction. A conveying device characterized by:

2. The control means a standby position for the skew detection means to detect the edge in the second direction is varied depending on the size of the medium; The conveying device according to claim 1 .

3. The control means During a detection interval from when the skew detection means detects an edge in the second direction near the leading end of the medium in the first direction until when the skew detection means detects an edge in the second direction near the trailing end of the medium in the first direction, moving the medium to a position where the skew detection means does not detect it; The conveying device according to claim 1 .

4. The control means setting the detection interval based on medium information relating to the size or thickness of the medium; The conveying device according to claim 3 .

5. the skew detection means detects the leading edge of the medium in the first direction before detecting the end in the second direction. The conveying device according to claim 1 .

6. the transport means includes a first transport means that transports the medium in the first direction and a switchback transport means that transports the medium in a direction opposite to the first direction, the control means also controls the operation of the first transport means and the switchback transport means, and sets the transport amount of the medium by the switchback transport means in accordance with the amount of skew detected by the skew detection means. The conveying device according to claim 1 .

7. the control means moves the skew detection means to a position where the edge of the medium in the second direction near the leading end of the medium in the first direction can be detected based on a transport timing of the medium notified from an external device; The conveying device according to claim 1 .

8. The medium may further include a punching means that is held rotatably about an axis in the second direction, and the punching means is configured to perform a perforation process on the medium. the control means varies the angle of rotation of the punching means in accordance with the amount of skew. The conveying device according to claim 1 .

9. The housing and an image forming unit housed in the housing and forming an image on a sheet-like medium; a conveying device according to claim 1 , which is detachably supported by the housing and conveys the medium on which an image is formed by the image forming means; An image forming system comprising:

Images