Sheet processing apparatus and image forming apparatus

Abstract

This technology provides a way to minimize contact between the perforating section used to punch holes in the sheet and the sheet itself. [Solution] The sheet processing apparatus includes a conveying means for conveying a sheet along a conveying path, a perforating means for perforating the sheet conveyed by the conveying means, a moving means for moving the perforating means in a direction intersecting the conveying direction of the sheet, a detection means provided upstream of the perforating means in the conveying path and detecting a first conveying position which is the position of the sheet conveyed by the conveying means in the width direction perpendicular to the conveying direction, and a control means that acquires size information relating to the size of the sheet, determines a second conveying position which is the position of the sheet in the width direction when the sheet is conveyed by the conveying means based on the size information, and controls whether or not to perform an avoidance process to move the perforating means away from the sheet by comparing the first conveying position and the second conveying position.

Description

Technical Field

[0005]

[0001] The present invention relates to a sheet processing apparatus for punching a sheet, and an image forming apparatus including the sheet processing apparatus.

Background Art

[0002] A sheet processing apparatus that performs various processes on a sheet on which an image is formed by an image forming apparatus such as a copier or a printer is used. One of the processes performed by the sheet processing apparatus is a punching process for the sheet. The holes provided in the sheet by the punching process can be used for filing the sheet or the like. There are two punching methods: a method of stacking a plurality of sheets in order and then punching them collectively, and a method of punching one sheet at a time while conveying the sheet.

[0003] In the method of punching collectively, it is necessary to provide a mechanism for holding a plurality of sheets stacked and a mechanism for aligning the plurality of held sheets, which increases the size of the sheet processing apparatus. Also, the processing speed may decrease due to the alignment operation. On the other hand, in the method of punching one sheet at a time, a mechanism for holding a plurality of sheets stacked and a mechanism for aligning a plurality of sheets are not required, the apparatus can be miniaturized, and a decrease in the processing speed can be suppressed.

[0004] Patent Document 1 discloses a sheet processing apparatus that punches a sheet one by one while conveying the sheet. According to Patent Document 1, a punching unit that punches a sheet in the sheet processing apparatus is configured to be movable in an intersecting direction that intersects the sheet conveying direction. Further, the sheet processing apparatus includes a detection unit that detects an end position of the sheet in the width direction orthogonal to the sheet conveying direction. By adjusting the position of the punching unit based on the detection result by the detection unit, punching can be performed with high accuracy with respect to the target punching position.

Prior Art Documents

Patent Documents

[0005] [

Patent Document 1

[0006] According to Patent Document 1, the sheet processing device pre-moves the perforating unit to a predetermined position corresponding to the size of the sheet before the sheet is transported to the perforating position. However, if the sheet is transported with a large misalignment in the width direction, contact will occur between the perforating unit waiting at the predetermined position and the sheet. Contact will also occur between the perforating unit and the sheet if the size of the sheet to be transported differs significantly from the size of the sheet actually transported. When the sheet comes into contact with the perforating unit, the transport of the sheet may stop.

[0007] This invention provides a technique to suppress contact between the perforating section used to perforate a sheet and the sheet itself. [Means for solving the problem]

[0008] According to one aspect of the present invention, a sheet processing apparatus includes: a conveying means for conveying a sheet along a conveying path; a perforating means for perforating the sheet conveyed by the conveying means; a moving means for moving the perforating means in a direction intersecting the conveying direction of the sheet; a detection means provided upstream of the perforating means in the conveying path and detecting a first conveying position which is the position of the sheet conveyed by the conveying means in the width direction perpendicular to the conveying direction; and a control means that acquires size information relating to the size of the sheet, determines a second conveying position which is the position of the sheet in the width direction when the sheet is conveyed by the conveying means based on the size information, and controls whether or not to perform an avoidance process to move the perforating means away from the sheet by comparing the first conveying position and the second conveying position. [Effects of the Invention]

[0009] According to the present invention, contact between the perforating portion used to perforate the sheet and the sheet itself can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] A diagram showing the configuration of an image forming apparatus according to one embodiment. [Figure 2] A diagram showing the configuration of a perforated section according to one embodiment. [Figure 3] A diagram showing the configuration of a movable module for the drilling section according to one embodiment. [Figure 4] A diagram showing the control configuration of an image forming apparatus according to one embodiment. [Figure 5] A functional block diagram relating to the control of an image forming apparatus according to one embodiment. [Figure 6] A diagram illustrating the operation of a sheet processing device according to one embodiment. [Figure 7] A diagram illustrating the operation of a sheet processing device according to one embodiment. [Figure 8] A flowchart of the process executed by the main control unit according to one embodiment. [Figure 9] A diagram illustrating the specific operation of a sheet processing device according to one embodiment. [Figure 10] A functional block diagram relating to the control of an image forming apparatus according to one embodiment. [Figure 11] A diagram showing an example of information used by a width estimation unit according to one embodiment for estimating sheet width. [Figure 12] A diagram illustrating the operation of a sheet processing device according to one embodiment. [Figure 13] A diagram illustrating the operation of a sheet processing device according to one embodiment. [Figure 14] A flowchart of the process executed by the main control unit according to one embodiment. [Figure 15] A diagram illustrating the specific operation of a sheet processing device according to one embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

[0012] <First Embodiment> FIG. 1 is a cross-sectional view of an image forming apparatus 1 having a sheet processing apparatus 4 according to the present embodiment. Note that FIG. 1 can also be regarded as an image forming system including the sheet processing apparatus 4 and the image forming apparatus 1. The image forming apparatus 1 has a cartridge 8 provided with a photoreceptor 9. During image formation, the photoreceptor 9 is rotationally driven and charged to a predetermined potential by a charging unit in the cartridge 8. The exposure unit 15 forms an electrostatic latent image on the charged photoreceptor 9 by exposing the photoreceptor 9. The developing unit in the cartridge 8 forms a toner image on the photoreceptor 9 by developing the electrostatic latent image of the photoreceptor 9 with toner.

[0013] On the other hand, the sheet stored in the cassette 6 is fed onto the conveyance path by rollers provided along the conveyance path and is conveyed along the conveyance path. In the present embodiment, the sheet is conveyed such that the central position in the width direction, which is parallel to the sheet surface and orthogonal to the conveyance direction of the sheet, coincides with a predetermined position in the width direction of the conveyance path. When the central position in the width direction of the sheet coincides with the predetermined position in the width direction of the conveyance path, the position of one reference end of the two ends in the width direction of the conveyed sheet is determined according to the length in the width direction of the sheet (hereinafter referred to as the sheet width). In the following description, the position in the width direction of the reference end corresponding to this sheet is referred to as the reference conveyance position. The reference conveyance position varies depending on the sheet width. In this example, the predetermined position in the width direction of the conveyance path is the central position in the width direction of the conveyance path.

[0014] Returning to FIG. 1, the sheet fed onto the conveyance path is conveyed along the conveyance path by rollers provided along the conveyance path toward the nip region between the photoreceptor 9 and the transfer roller 10. The transfer roller 10 outputs a transfer bias voltage to transfer the toner image on the photoreceptor 9 onto the sheet. In this way, the cartridge 8 is an image forming unit that forms a toner image on the sheet by transferring the toner image formed on the photoreceptor 9 onto the sheet. Also, the cartridge 8 and the exposure unit 15 can be regarded as an image forming unit that forms a toner image on the sheet.

[0015] In the conveyance direction of the sheet, upstream of the nip region between the photoreceptor 9 and the transfer roller 10, a registration sensor 40 (hereinafter referred to as the registration sensor 40) for detecting the sheet is provided. The detection result of the sheet by the registration sensor 40 is used for controlling the timing of feeding the sheet into the nip region between the photoreceptor 9 and the transfer roller 10 and the like. The fixing unit 11 fixes the toner image onto the sheet by heating and pressing the sheet onto which the toner image has been transferred. The sheet that has passed through the fixing unit 11 is conveyed toward the sheet processing apparatus 4 by the conveyance rollers 50, 51, and 52. A conveyance sensor 135 for detecting the sheet is provided between the conveyance roller 51 and the conveyance roller 52. The sheet conveyed to the sheet processing apparatus 4 is conveyed by the inlet roller 21 and the outlet roller 22.

[0016] Between the inlet roller 21 and the outlet roller 22, an inlet sensor 27 for detecting the presence or absence of a sheet, a line sensor 61 for detecting the sheet's transport position in the width direction, and a perforation section 62 for perforating the sheet are provided along the sheet's transport direction. The detection result of the inlet sensor 27 is used to determine the timing for the line sensor 61 to detect the sheet, etc. The line sensor 61 is an image sensor in which a light source, a light-receiving element, and a lens are arranged in an array, and is positioned so that the reference end of the sheet passes between the light source and the light-receiving element. The reference end is, as described above, the end of the sheet corresponding to the reference transport position. Based on the amount of light received by the light-receiving element, the line sensor 61 detects the position of the reference end of the sheet in the width direction as the transport position of the sheet in the width direction. In the following description, "transport position" refers to the position in the width direction unless otherwise specified.

[0017] The perforating section 62 is configured to be movable in the width direction. By moving the perforating section 62 in the width direction according to the sheet transport position detected by the line sensor 61, the target position for perforation on the sheet can be accurately perforated by the perforating section 62. The sheet that has passed through the perforating section 62 is discharged to the tray 25 by the discharge roller 24. In addition to the tray 25, the sheet processing device 4 also has a tray 37 as a destination for sheet discharge. When the destination for sheet discharge is the tray 37, the discharge roller 24 stops rotating just before discharging the sheet to the tray 25, and then rotates in the opposite direction. Due to the reverse rotation of the discharge roller 24, the sheet is transported to the intermediate loading section 39 by rollers 26, 28, and 29. One or more sheets are loaded into the intermediate loading section 39, and if necessary, they are stapled together using a stapler (not shown). Subsequently, one or more sheets on the intermediate loading section 39 are pushed out by the discharge guide 34 connected to the guide drive unit 35 and discharged onto the tray 37 by the discharge roller 36.

[0018] Figure 2 is a diagram of the perforation section 62. The punch 202 is configured to rotate around the axis 65 as its center of rotation. The die 205 is also configured to rotate around the axis 66 as its center of rotation. The punch 202 is driven to rotate in a clockwise direction in Figure 2, and the die 205 is driven to rotate in a counterclockwise direction in Figure 2, synchronously with the punch 202. The die 205 is provided with a die hole 206 at a position corresponding to the punch 202. The die 205 is also provided with a fan-shaped sensor flag 131. The sensor flag 131 is positioned to cross the optical path from the light-emitting element to the light-receiving element of the photointerrupter 130, according to the rotation phase of the die 205. The photointerrupter 130 detects the sensor flag 131 based on the amount of light received by the light-receiving element.

[0019] Figure 2(A) shows the state where the rotation phase (rotation position) of the punch 202 is the standby phase. The standby phase is the state where the angle 67 between the punch 202 and the punching phase 75 (see Figure 2(C)), when the punch 202 can punch a sheet, is a predetermined value, and the punch 202 is controlled to wait in the standby phase until the sheet to be punched is conveyed. Note that the standby phase of the punch 202 is set so as not to interfere with the conveyance of the sheet. Figure 2(B) shows the state where the rotation phase of the punch 202 is the start phase 70, when punching into the sheet begins. Figure 2(C) shows the state where the rotation phase of the punch 202 is the punching phase 75. In this state, the punch 202 and the die hole 206 engage, and the punch 202 can punch a sheet. Figure 2(D) shows the state where the rotation phase of the punch 202 is the end phase 71.

[0020] The sensor flag 131 is configured such that the photointerrupter 130 is in a light-blocking state within the range from the start phase 70 to the end phase 71, and in a light-transmitting state outside of that range. By monitoring the timing of the state change of the photointerrupter 130 while rotating the die 205, the rotation phase of the punch 202 is detected. For example, the timing at which the state of the photointerrupter 130 changes from the light-transmitting state to the light-blocking state is the timing at which the rotation phase of the punch 202 becomes the start phase 70. By stopping the rotation of the punch 202 at a predetermined timing based on this timing, the punch 202 can be stopped at the punching phase 75.

[0021] Next, the movement module for moving the perforation section 62 in the width direction will be described. Figure 3(A) is a plan view of the movement module as seen from above the sheet processing device, and Figure 3(B) is a side view of the movement module as seen in the transport direction. In Figure 3, reference numeral 210 denotes a sheet, and reference numeral 410 denotes the transport direction of the sheet. In Figure 3, the perforation section 62 is configured to be movable in the width direction 411.

[0022] The drilling section 62 is supported by a base section 403. The base section 403 is movably supported by guide shafts 401 and 402 extending in the width direction 411. The base section 403 has a rack gear 404 extending in the width direction 411. The moving module has a shift motor 406 and an idler gear 405 rotationally driven by the shift motor 406, the idler gear 405 meshing with the rack gear 404. The shift motor 406 is, for example, a stepping motor. By driving the shift motor 406, the drilling section 62 supported by the base section 403 moves in the width direction 411 along the guide shafts 401 and 402.

[0023] The mobile module also has a home position sensor 407. The home position sensor 407 is, for example, a photointerrupter and detects the detected part 62a provided on the perforating unit 62. Reference numeral 413 in Figure 3(A) indicates the position at which the detection state of the detected part 62a by the home position sensor 407 switches. In this embodiment, when no perforating is performed, the perforating unit 62 waits when the detected part 62a reaches position 413. In the following description, this position where the perforating unit 62 waits will be referred to as the home position. The home position is set so that the perforating unit 62 waiting there does not interfere with the sheet being transported. The position of the perforating unit 62 in the width direction is managed by the number of pulses input to the shift motor 406, with the home position as the reference.

[0024] The perforating section 62 is configured to allow the sheet 210 to pass between the punch 202 and the die 205. In this example, as shown in Figure 3(B), the perforating section 62 is provided with an opening for the sheet to pass through. The opening has a "U" shape when viewed in the direction of transport. The position where the perforating section 62 perforates the sheet is on the sheet 210, at a predetermined distance 408 in the width direction from the left edge (reference edge) of the sheet 210 in the direction of transport. Hereinafter, this position will be referred to as the target perforation position. When perforating, the position of the perforating section 62 in the width direction is adjusted so as to perforate the target perforation position. When the position of the perforating section 62 in the width direction is such that it can perforate the target perforation position, the distance between the left edge of the sheet 210 and the end 412 of the opening of the perforating section 62 in the width direction is J. If the perforation section 62 is located at the position shown in Figure 3(B), and the reference edge of the sheet 210 is transported with a displacement of J or more to the left, the sheet 210 and the perforation section 62 will interfere with each other, hindering the transport of the sheet.

[0025] Figure 4 is a block diagram showing the hardware configuration of the image forming apparatus 1. Figure 4 basically shows the parts of the hardware configuration of the image forming apparatus 1 necessary for explaining this embodiment. The video controller 119 controls the entire image forming apparatus 1. The engine control unit 301 controls image formation on the sheet. For example, the engine control unit 301 controls the transport unit to feed the sheet stored in the cassette 6 onto the transport path and transport it to the sheet processing apparatus 4. The transport unit includes rollers provided along the transport path and motors that rotate these rollers. The engine control unit 301 also controls the cartridge 8 and the exposure unit 15 to form a toner image on the photoreceptor 9 and transfer the toner image from the photoreceptor 9 to the sheet transported by the transport unit. Furthermore, the engine control unit 301 controls the fuser unit 11 to fix the toner image to the sheet. The engine control unit 301 also receives the sheet detection result from the register sensor 40 via the input circuit 316.

[0026] The main control unit 101 controls the sheet processing device 4. The CPU 306 of the main control unit 101 is a central processing unit that controls various operations of the sheet processing device 4. The RAM 307 is a volatile memory that temporarily stores control data necessary for the operation of the sheet processing device 4. The ROM 308 is a non-volatile memory that stores programs and control tables necessary for the operation of the sheet processing device 4. The system timer 111 generates the timing necessary for various controls in the sheet processing device 4. The communication interface 315 communicates with the video controller 119. The above components of the main control unit 101 and the I / O port 310 described below are configured to communicate with each other via the bus 309. The I / O port 310 provides input / output interfaces to various units of the sheet processing device 4. Specifically, the I / O port 310 receives the detection results of the sheet transport position by the line sensor 61, the sheet detection results by the entrance sensor 27, and the detection results of the detected part 62a by the home position sensor 407 via the input circuits 311, 312, and 317. Furthermore, the I / O port 310 outputs drive signals to the punch motor 102, the shift motor 406, and the transport motor 325 via the drive circuits 313, 314, and 322. The punch motor 102 is a motor that rotates the punch 202 and the die 205. The transport motor 325 is a motor that drives multiple rollers that transport the sheet in the sheet processing device 4. The transport motor 325 and the multiple rollers constitute the sheet transport section.

[0027] Figure 5 is a functional block diagram showing the functional configuration of the image forming apparatus 1 according to this embodiment. Note that Figure 5 shows only the parts related to sheet perforation control, and other parts are omitted. Signals from the entrance sensor 27, line sensor 61, and home position sensor 407 are input to the sensor control unit 116. The communication interface 315 receives print information related to printing from the video controller 119. The print information includes information indicating whether or not to perforate the sheet. If perforation is performed, the print information includes perforation information such as the perforation interval and number of perforations in the transport direction, and size information indicating the size of the sheet to be perforated. Note that the size information includes information indicating or determining the length in the width direction of the sheet (hereinafter referred to as sheet width) and the length in the transport direction of the sheet (hereinafter referred to as sheet length). The content of this print information is based on information set by the user via the operation unit (not shown) of the image forming apparatus 1 when the user performs image formation on the sheet. Alternatively, the content of this print information is based on the information contained in the print job that the image forming apparatus 1 receives from the host computer, which is an external device, when the user forms an image on the sheet. The information contained in the print job is based on the information that the user has set on the host computer.

[0028] The system timer 111 generates various timings related to sheet transport and the movement of the punching unit 62 based on print information from the video controller 119. The motor control unit 117 drives and controls the punch motor 102, shift motor 406, and transport motor 325 based on the various timings generated by the system timer 111. The determination unit 321 determines the reference transport position of the sheet based on the sheet width indicated by the size information acquired by the communication interface 315, or determined based on the size information. The determination unit 321 compares the determined reference transport position with the sheet transport position detected by the line sensor 61 to determine whether avoidance processing of the punching unit 62 is necessary. Avoidance processing is the process of moving the punching unit 62 toward the home position so that it moves away from the sheet so that the punching unit 62 does not interfere with the sheet. If avoidance processing is determined to be necessary, the determination unit 321 instructs the motor control unit 117 to execute the avoidance processing. When the motor control unit 117 receives an instruction from the determination unit 321 to execute the avoidance process, it outputs a drive signal to the shift motor 406 to perform the avoidance process for the drilling section 62.

[0029] The processing performed by the main control unit 101 will be explained using Figures 6 and 7. Figure 6(A) shows the initial state before the sheet is transported, and the main control unit 101 has the perforating unit 62 waiting at the home position. Figure 6(B) shows the state before the sheet 210 reaches the entrance roller 21, and the determination unit 321 moves the perforating unit 62 to the reference waiting position based on the reference transport position of the sheet 210. The determination unit 321 determines the reference transport position based on size information obtained from the video controller 119. The reference waiting position is, for example, the position where the end 412 of the perforating unit 62 shown in Figure 3(B) is a distance J away from the reference transport position of the sheet. In Figure 6(B), the sheet 210 is shown to illustrate the relationship between the transport position of the sheet 210 and the reference waiting position, but the sheet 210 is not actually in the position shown, but is further upstream on the transport path. For this reason, the sheet 210 is shown with a dotted line in Figure 6(B). In Figure 6(B), the dotted circle on the sheet 210 indicates the target perforation position. Figure 6(C) shows the state when the sheet 210 has reached the detection position of the line sensor 61. In Figure 6(C), the transport position detected by the line sensor 61 is approximately the same as the reference transport position. The determination unit 321 determines that avoidance processing is necessary if the difference between the transport position and the reference transport position is greater than the first threshold, and that avoidance processing is unnecessary if it is less than or equal to the first threshold. In this example, since the difference between the transport position and the reference transport position is less than or equal to the first threshold, the determination unit 321 determines that avoidance processing is unnecessary.

[0030] Figure 6(D) shows the leading edge of the sheet 210 passing through the perforating section 62, with the perforating section 62 having made one hole in the sheet 210. The solid circle on the sheet 210 indicates that it has been perforated. Figure 7(A) shows the sheet 210 after it has passed through the perforating section 62. Once the perforation of the sheet 210 is complete, the main control unit 101 moves the perforating section 62 toward the home position. In this way, if the amount of skew of the sheet 210 is small and the sheet 210 is being transported at approximately the standard transport position, the normal perforation process is performed.

[0031] On the other hand, Figure 7(B) shows the case where the sheet 210 is transported at a position significantly shifted in the width direction from the reference transport position. The dotted rectangle in Figure 7(B) represents the sheet when it is transported at the reference transport position. The reason why the transport position of the sheet 210 is significantly shifted in the width direction from the reference transport position is, for example, that the sheet 210 was not placed in the correct position within the cassette 6, or that the cassette 6 itself was not properly mounted in the image forming apparatus 1. If the difference between the transport position detected by the line sensor 61 and the reference transport position is greater than the first threshold, the determination unit 321 determines that the sheet 210 will interfere with the perforation unit 62 and executes an avoidance process. In this example, the determination unit 321 determines that an avoidance process is necessary and instructs the motor control unit 117 to execute the avoidance process. When an avoidance process is instructed, the motor control unit 117 drives the shift motor 406 to move the perforation unit 62 toward the home position, that is, to move the perforation unit 62 away from the sheet, as shown in Figure 7(B). Figure 7(C) shows the state in which the perforation section 62 has been retracted to the home position due to the avoidance process. As shown in Figure 7(C), the sheet 210 does not interfere with the perforation section 62, and the sheet 210 is transported as is.

[0032] Figure 8 is a flowchart of the process executed by the main control unit 101, including the determination unit 321. At the start of the process in Figure 8, the perforation unit 62 is waiting at the home position. When a sheet is transported, the main control unit 101 determines in S10 whether the sheet is to be perforated or not based on the print information obtained from the video controller 119. If the sheet is not to be perforated, the main control unit 101 repeats the process from S10. On the other hand, if the sheet is to be perforated, the main control unit 101 moves the perforation unit 62 to the reference waiting position in S11. The reference waiting position is a position based on the reference transport position of the sheet being transported. The reference transport position of the sheet is determined based on the size information included in the print information obtained from the video controller 119, more specifically, based on the sheet width of the sheet being transported. In S12, the main control unit 101 determines the transport position of the sheet from the detection result by the line sensor 61. The timing of sheet detection by the line sensor 61 is determined based on the timing when the entrance sensor 27 detects the sheet.

[0033] In S13, the main control unit 101 determines the difference between the reference transport position of the sheet and the transport position of the sheet detected by the line sensor 61 as the amount of displacement in the width direction of the transport position, and compares this displacement amount with a first threshold. If the displacement amount is greater than the first threshold, the main control unit 101 performs the avoidance process described above in S15; otherwise, the main control unit 101 performs the perforation process by the perforation unit 62 in S14. It is also possible to configure the system to perform the avoidance process when the displacement amount is greater than the first threshold and the transport position of the sheet detected by the line sensor 61 is closer to the perforation unit 62 than the reference transport position. This is because even if the displacement amount is greater than the first threshold, if the transport position of the sheet detected by the line sensor 61 is farther from the perforation unit 62 than the reference transport position, the sheet and the perforation unit 62 will not interfere with each other.

[0034] Next, the first threshold used in S13 of Figure 8 will be explained using Figure 9. Figure 9 shows the state before the leading edge of the sheet 210 reaches the detection position of the line sensor 61. Reference numeral 211 indicates the sheet when it is transported at the reference transport position. As shown in Figure 9, the perforation unit 62 (shown by a dotted line) is waiting at the reference standby position. In this example, since the sheet 210 interferes with the perforation unit 62 waiting at the reference standby position, the main control unit 101 performs avoidance processing. Here, the widthwise distance D [mm] that the perforation unit 62 can move from the time the line sensor 61 detects the transport position of the sheet at the leading edge of the sheet 210 until the leading edge of the sheet 210 reaches the position of the perforation unit 62 in the transport direction can be calculated by the following formula. D = C × (A / B) (1) Here, A[mm] is the distance in the transport direction from the line sensor 61 to the perforation unit 62, B[mm / sec] is the transport speed of the sheet 210, and C[mm / sec] is the movement speed of the perforation unit 62.

[0035] As explained using Figure 3(B), the distance between the reference edge of the sheet 210 being transported at the reference transport position and the edge 412 of the perforating unit 62 waiting at the reference standby position is J [mm]. Therefore, the maximum amount of displacement E [mm] of the sheet 210 that can avoid interference between the perforating unit 62 and the sheet 210 through avoidance processing can be calculated using the following formula. E = D + J (2)

[0036] For example, if A = 60 [mm], B = 400 [mm / sec], and C = 60 [mm / sec], then from equation (1), D = 9 [mm]. If J = 2 [mm], then from equation (2), the maximum amount of displacement E of the sheet 210 that can avoid interference is 11 [mm]. The sheet processing device 4 may be configured, for example, so that the maximum expected amount of displacement is less than E.

[0037] The first threshold is set to a value less than the maximum value E, for example. Increasing the threshold means performing the perforation process as much as possible and minimizing the avoidance process. However, if the amount of deviation is too large, there is a high possibility that the sheet is not being transported properly, such as colliding with the wall of the transport path, and even if the perforation process is performed in this state, there is a high possibility that the accuracy and quality of the perforation will not be maintained. In addition, in order for the perforation unit 62 to perforate at the target perforation position, it is necessary to adjust the widthwise position of the perforation unit 62 waiting at the reference standby position according to the amount of deviation. However, if the amount of deviation is too large, the accuracy of adjusting the widthwise position of the perforation unit 62 will decrease, and there is a high possibility that the accuracy and quality of the perforation will not be maintained. Furthermore, if the amount of deviation is too large, the transport position of the leading edge of the sheet 210 may change after passing the line sensor 61 but before reaching the perforation unit 62, in which case unintended transport failures may occur or perforation may occur at a position significantly different from the target perforation position. Therefore, it is preferable to determine the boundary between the amount of deviation that allows the accuracy and quality of the drilling to be maintained and the amount of deviation that does not allow the accuracy and quality of the drilling to be maintained, and to set a value near this boundary as the first threshold, under the condition that it is less than the maximum value E.

[0038] As described above, according to this embodiment, the conveying position of the sheet upstream of the perforation section 62 is detected by the line sensor 61, and the amount of deviation from the reference conveying position is determined. Then, by comparing the amount of deviation with a first threshold, it is determined whether to perform perforation or avoidance processing. With this configuration, interference between the sheet and the perforation section 62 can be suppressed.

[0039] In this embodiment, the sheet transport position was detected by an optical line sensor 61. However, any other method capable of detecting the sheet transport position can be used. For example, a configuration can be used in which a photointerrupter that moves in the width direction and a sensor flag are used to detect the sheet transport position by contact between the sensor flag and the edge of the sheet. Furthermore, even if it is an optical system, it is possible to have a configuration in which the sensor itself moves in the width direction to detect the sheet transport position, rather than using an array of fixed light-receiving elements.

[0040] <Second Embodiment> Next, the second embodiment will be described, focusing on the differences from the first embodiment. Figure 10 is a block diagram showing the functional configuration of the image forming apparatus 1 according to this embodiment. Note that functional blocks similar to those in the block diagram of the first embodiment shown in Figure 5 are given the same reference numerals and their descriptions are omitted. The sheet length detection unit 324 of the engine control unit 301 receives information indicating the detection status of the sheet acquired by the register sensor 40 via the sensor control unit 319. The sheet length detection unit 324 uses the system timer 323 to determine the time the register sensor 40 detected the sheet, and determines the sheet length, which is the length of the sheet in the conveying direction, based on the time the register sensor 40 detected the sheet and the sheet conveying speed. The engine control unit 301 notifies the main control unit 101 of the sheet processing apparatus 4 of the information indicating the determined sheet length (hereinafter also referred to as the detected sheet length) via the video controller 119.

[0041] The width estimation unit 320 of the main control unit 101 acquires information indicating the detected sheet length from the communication interface 315 and estimates the sheet width based on this information. In the following description, the sheet width estimated by the width estimation unit 320 will also be referred to as the estimated sheet width. The sheet width estimation will be explained later. Also, similar to the first embodiment, the determination unit 321 acquires size information from the communication interface 315 and determines whether avoidance processing is necessary based on the sheet width based on the size information (hereinafter also referred to as the set sheet width) and the estimated sheet width from the width estimation unit 320. If it is determined that avoidance processing is necessary, the determination unit 321 instructs the motor control unit 117 to execute the avoidance processing.

[0042] Figure 11 shows an example of the information used by the width estimation unit 320 when estimating the sheet width based on the detected sheet length. The information in Figure 11 is provided for each of the multiple sizes that can be transported or used by the image forming apparatus 1. In the table in Figure 11, "Standard Size Type" indicates the name of the sheet size defined by the standard, and "Standard Sheet Width" and "Standard Sheet Length" indicate the sheet width and sheet length defined by the standard. The width estimation unit 320 determines which record's "Upper Limit" and "Lower Limit" range the detected sheet length falls within in Figure 11, and uses the standard sheet width of the determined record's standard as the estimated sheet width. For example, suppose the detected sheet length is 360.2 mm. In this case, since the sheet length is within the range of the lower limit (347.8 mm) and upper limit (365.6 mm) of the LGL size, the width estimation unit 320 determines that the estimated sheet width is 215.9 mm, which is the standard sheet width of the LGL size. Similarly, if the detection sheet length is 300.0 mm, the width estimation unit 320 determines that the estimated sheet width is 210.0 mm, which is the standard sheet width for A4 size. In Figure 11, the sheets that can be transported or used by the image forming apparatus 1 are defined by a standard size, but the present invention is not limited to sheets that can be transported or used by the image forming apparatus 1 being defined by a standard size. Specifically, regardless of whether or not the sheets are defined by a standard size, the present invention can be configured to determine the estimated sheet width for each sheet that can be transported or used by the image forming apparatus 1 using information showing the relationship between the detection sheet length and the estimated sheet width.

[0043] Next, the processing performed by the main control unit 101 in this embodiment will be explained using Figures 12 and 13. Figures 12 and 13 show the sheet transport path from the register sensor 40 to the exit roller 22. Figure 12(A) shows the state before the sheet is transported, and the perforating unit 62 is waiting at the home position. Figure 12(B) shows the state immediately after the transport of the sheet 210 has started, and the main control unit 101 moves the perforating unit 62 to the reference waiting position based on the size information of the print information acquired from the video controller 119. As in the first embodiment, the reference waiting position is determined based on the reference transport position, and the reference transport position is determined based on the "set sheet width" indicated by the size information or determined based on the size information. Figure 12(C) shows the state immediately after the rear end of the transported sheet 210 has passed the register sensor 40. At this timing, the sheet length detection unit 324 detects the sheet length. In this example, it is assumed that the sheet length detected by the sheet length detection unit 324 and the sheet length based on the size information notified by the engine control unit 301 to the main control unit 101 are approximately the same. In this case, the estimated sheet width and the set sheet width are also approximately the same. The determination unit 321 determines that the sheet 210 and the perforation unit 62 will interfere if half the difference between the estimated sheet width and the set sheet width is greater than the second threshold, and that the sheet 210 and the perforation unit 62 will not interfere otherwise. In this example, since half the difference between the estimated sheet width and the set sheet width is less than the second threshold, the determination unit 321 determines that the sheet 210 and the perforation unit 62 will not interfere. Therefore, the determination unit 321 determines to execute the perforation process by the perforation unit 62.

[0044] Figure 12(D) shows the leading edge of the sheet 210 passing through the perforating section 62, with the perforating section 62 having made one hole in the sheet 210. The solid circle on the sheet 210 indicates that it has been perforated. Figure 13(A) shows the sheet 210 after it has passed through the perforating section 62. Once the perforation of the sheet 210 is complete, the main control unit 101 moves the perforating section 62 toward the home position. In this way, if the difference between the estimated sheet width and the set sheet width is small, the normal perforation process is performed.

[0045] On the other hand, Figure 13(B) shows a case where the size of the sheet 210 differs significantly from the size notified by the engine control unit 301. Figure 13(B) shows the state when the rear end of the conveyed sheet 210 has passed the register sensor 40. At this timing, the sheet length detection unit 324 detects the sheet length. The width estimation unit 320 determines the estimated sheet width based on the detected sheet length. In this example, the estimated sheet width is assumed to be greater than the set sheet width, and half the difference is greater than the second threshold. In this case, the determination unit 321 determines that avoidance processing is necessary and instructs the motor control unit 117 to execute the avoidance processing.

[0046] Figure 13(C) shows the state in which the perforation section 62 has been retracted to the home position due to the avoidance process. As shown in Figure 13(C), the sheet 210 does not interfere with the perforation section 62, and the sheet 210 is transported as is.

[0047] Figure 14 is a flowchart of the process executed by the main control unit 101 in this embodiment. At the start of the process in Figure 14, the perforating unit 62 is waiting at the home position. When a sheet is transported, the main control unit 101 determines in S10 whether the sheet is to be perforated or not based on the print information obtained from the video controller 119. If the sheet is not to be perforated, the main control unit 101 repeats the process from S10. On the other hand, if the sheet is to be perforated, the main control unit 101 moves the perforating unit 62 to the reference waiting position in S11. The main control unit 101 determines the reference waiting position based on the size information included in the print information. Subsequently, in S20, the main control unit 101 obtains the sheet length detected by the sheet length detection unit 324 from the video controller 119. In S21, the main control unit 101 estimates the sheet width based on the obtained sheet length, that is, determines the estimated sheet width.

[0048] In S23, the main control unit 101 uses half the difference (width difference) between the estimated sheet width and the set sheet width as a determination value and compares it with a second threshold. If the determination value is greater than the second threshold, the main control unit 101 performs the avoidance process described above in S15; otherwise, the main control unit 101 performs the perforation process using the perforation unit 62 in S14. Note that the determination value in S23 can also be half the value obtained by subtracting the set sheet width from the estimated sheet width. In other words, even if the determination value is greater than the second threshold, if the estimated sheet width is smaller than the set sheet width, the perforation process is performed instead of the avoidance process. This is because if the estimated sheet width is smaller than the set sheet width, the perforation unit 62 and the sheet do not interfere with each other.

[0049] Normally, a sheet of the same size as the size notified to the main control unit 101 from the video controller 119 is actually transported, and the main control unit 101 performs the perforation process based on the notified sheet size. However, there are cases where a sheet of a different size than the size notified by the video controller 119 is transported. For example, some image forming apparatuses 1 do not have a function to detect the size of sheets stored / placed in the cassette 6 or the manual feed tray (not shown in Figure 1). In such an image forming apparatus 1, if the size of the sheet stored in the cassette 6 or placed in the manual feed tray is different from the size set in the image forming apparatus 1, the size of the sheet actually transported may differ from the notified size.

[0050] If the set sheet width, that is, the sheet width set by the user, differs from the estimated sheet width, that is, the sheet width determined from the actually detected sheet length, the perforation unit 62 and the sheet may interfere with each other. For this reason, avoidance processing is necessary, as in the first embodiment. In this embodiment, in order to prevent the perforation unit 62 from interfering with the sheet, it is necessary to move the perforation unit 62 by a distance of half the difference between the set sheet width and the estimated sheet width. In other words, compared to moving the perforation unit 62 by the amount of the sheet transport position displacement caused by the sheet's skew, as in the first embodiment, the amount of movement of the perforation unit 62 in the avoidance processing is significantly larger.

[0051] For example, if a sheet of the size shown in Figure 11 is available in the image forming apparatus 1, the maximum width difference is 67.9 mm when the set sheet width is 148.0 mm, which corresponds to A5, and the estimated sheet width is 215.9 mm, which corresponds to LGL. In this embodiment, in this case, the maximum movement amount of the perforation section 62 is 33.95 mm, which is half of the maximum width difference of 67.9 mm.

[0052] On the other hand, since the displacement in the first embodiment is at most a few millimeters, the amount of movement required to avoid the perforation section 62 is also only a few millimeters. Therefore, it is possible to move the perforation section 62 to a position where it does not interfere with the sheet after the leading edge of the sheet reaches the line sensor 61, but before the leading edge of the sheet reaches the position of the perforation section 62 in the transport direction.

[0053] However, as in this embodiment, if the amount of movement of the perforation section 62 required for the avoidance process is as much as 33.95 mm, it would be too late to start the avoidance process after the leading edge of the sheet reaches the line sensor 61. For this reason, in this embodiment, the necessity of performing the avoidance process is determined at an earlier timing than in the first embodiment, that is, when the trailing edge of the sheet passes the register sensor 40, and the avoidance process is performed as necessary. In this embodiment, the necessity of the avoidance process is determined before the sheet is transported to the sheet processing device 4, but the present invention is not limited to such a configuration. For example, if the transport distance to the perforation section 62 within the sheet processing device 4 is long, and the necessary amount of movement for the perforation section 62 can be secured even if the avoidance process is started after the sheet length is detected within the sheet processing device 4, then the sheet length may be detected within the sheet processing device 4. Also, for example, the sheet length can be detected by the transport sensor 135 after image formation has been performed on the sheet.

[0054] Next, using Figure 15, the travel distance of the perforating unit 62 in the avoidance process of this embodiment will be explained. Figure 15 shows the state in which the rear end of the actually transported sheet 210 has reached the detection position of the register sensor 40. Reference numeral 211 indicates a sheet of a size set by the user in the image forming apparatus 1. As shown in Figure 15, the perforating unit 62 (shown by a dotted line) is waiting at the reference standby position. In this example, since the sheet 210 interferes with the perforating unit 62 waiting at the reference standby position, the main control unit 101 performs an avoidance process. Here, the distance D [mm] in the width direction that the perforating unit 62 can move from the time the width estimation unit 320 determines the estimated sheet width based on the detected sheet length until the front end of the sheet 210 reaches the position of the perforating unit 62 in the transport direction is calculated by the following formula. D = C × (H / B) (3) Here, H[mm] is the distance from the front of the sheet 210 to the perforation section 62 when the rear end of the sheet 210 is at the position of the register sensor 40, B[mm / sec] is the transport speed of the sheet 210, and C[mm / sec] is the movement speed of the perforation section 62.

[0055] As shown in Figure 15, the amount of movement of the perforated section 62 required to avoid interference with the sheet 210 is I [mm]. Therefore, considering the distance J [mm] shown in Figure 3, interference between the perforated section 62 and the sheet 210 can be avoided if the following equation is satisfied. D>IJ (4) In this embodiment, since I >> J, if we ignore the distance J, interference between the perforated portion 62 and the sheet 210 can be avoided if the following equation is satisfied. D>I (5)

[0056] For example, let's assume the distance F from the register sensor 40 to the perforation section 62 is 670 [mm], the size set by the user in the image forming apparatus 1 is A5, and in reality, an LGL sheet is transported. In this case, as described above, I = 33.95 [mm]. Also, since the length of the LGL sheet G = 355.6 [mm], the distance H is 314.4 [mm]. If B = 400 [mm / sec] and C = 60 [mm / sec], the distance D is 47.16 [mm] from equation (3), which is larger than the distance I = 33.95 [mm], so interference between the perforation section 62 and the sheet 210 can be avoided.

[0057] If the type of sheet shown in Figure 11 is a sheet that can be transported or used by the image forming apparatus 1, then the specific values ​​of D[mm] and I[mm] above are the values ​​when the difference between the maximum and minimum sheet widths is maximized. In other words, it is the combination of the set sheet and the sheet actually transported in which D is minimized and I is maximized. If interference between the perforation section 62 and the sheet can be avoided in this combination, then it can be avoided in any other combination as well. Therefore, the second threshold should be set to a value smaller than the maximum value of I above, for example.

[0058] Increasing the second threshold means performing the perforation process as much as possible and minimizing the avoidance process. However, if the judgment value (half the difference in sheet width) is too large, the adjustment accuracy of the widthwise position of the perforation unit 62 will decrease, and there is a high possibility that the accuracy and quality of the perforation will not be maintained. Also, if the judgment value is too large, there is a high possibility that the user has set the wrong sheet, and performing the perforation process on the wrong sheet is not the behavior the user would want. Therefore, it is preferable to set an appropriate second threshold after determining whether the judgment value should be used to determine whether to perform the perforation process or to determine whether to perform the avoidance process, from the perspective of the accuracy and quality of the perforation and usability.

[0059] As described above, according to this embodiment, the sheet length is detected upstream of the perforation unit 62, and the sheet width is estimated and determined based on the detected sheet length. Then, half of the difference between the determined or estimated sheet width and the set sheet width is used as an evaluation value, and by comparing this evaluation value with a second threshold, it is determined whether to perform perforation or avoidance processing. This configuration makes it possible to suppress interference between the sheet and the perforation unit 62. In addition, the mechanism for detecting the sheet length can be provided upstream of the image forming unit (cartridge 8) that transfers and forms an image on the sheet in the image forming apparatus 1, and the perforation unit 62 can be provided downstream of the image forming unit 8. With this configuration, it is possible to determine whether to perform perforation or avoidance processing at a timing considerably earlier than when the sheet reaches the perforation position, and a larger amount of movement of the perforation unit 62 can be secured than in the first embodiment. Therefore, avoidance processing is possible even if there is a large size difference between the set sheet and the sheet actually conveyed.

[0060] In this embodiment, half the difference between the set sheet width and the estimated sheet width was compared with the second threshold value, but it is also possible to configure the system to compare the difference between the set sheet width and the estimated sheet width with the second threshold value. Furthermore, although this embodiment has been explained based on the sheet width, it can also be explained based on the transport position, as in the first embodiment. Specifically, the main control unit 101 determines the set sheet width based on the size information obtained from the video controller 119, and determines the reference transport position based on the set sheet width. Subsequently, the main control unit 101 determines the estimated sheet width based on the sheet length detected by the sheet length detection unit 324, and then determines the transport position based on the estimated sheet width. The transport position based on the estimated sheet width is determined by the same criteria as the reference transport position based on the set sheet width. In this case, the difference between the transport position based on the estimated sheet width and the reference transport position corresponds to half the difference between the set sheet width and the estimated sheet width, that is, the evaluation value described above.

[0061] In this embodiment, the sheet length was detected by a register sensor 40 in a standard image forming apparatus 1, the estimated sheet width was determined based on the detected sheet length, and the sheet transport position was determined based on the estimated sheet width. However, similar to the first embodiment, it is also possible to configure the system to directly detect the transport position of the transported sheet, that is, the position of the reference end of the transported sheet in the width direction.

[0062] <Other forms> Furthermore, the image forming apparatus 1 can be configured to selectively perform the processing of the first embodiment and the processing of the second embodiment. Moreover, the image forming apparatus 1 can be configured to perform both the processing of the first embodiment and the processing of the second embodiment. In this case, for example, the first detection unit that detects the conveying position of the sheet is provided downstream of the second detection unit that detects the sheet length in the conveying path. In the above embodiment, the first detection unit corresponds to the line sensor 61, and the second detection unit corresponds to the register sensor 40. Also, the perforation unit 62 that perforates the sheet is provided downstream of the first detection unit in the conveying path. Furthermore, the second detection unit that detects the sheet length can be configured to be provided upstream of the image forming unit that forms an image on the sheet. The image forming unit corresponds to the cartridge 8 in the above embodiment. Moreover, the second detection unit that detects the sheet length can be configured to be provided downstream of the image forming unit that forms an image on the sheet.

[0063] Furthermore, in each of the above embodiments, the direction of movement of the perforating section 62 was in the width direction. However, if the position of the perforating section 62 in the width direction can be changed, the direction of movement of the perforating section 62 is not limited to the width direction. For example, the perforating section 62 can be configured to move in a direction that is not parallel to the conveying direction within a plane parallel to the sheet surface. Moreover, the direction of movement of the perforating section 62 does not have to be within a plane parallel to the sheet surface. In other words, the direction of movement of the perforating section 62 can be in a direction that intersects with the conveying direction of the sheet.

[0064] [Other embodiments] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0065] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0066] 21: Inlet roller, 22: Outlet roller, 62: Drilling section, 406: Shift motor, 61: Line sensor, 101: Main control unit

Claims

1. A conveying means for conveying a sheet along a conveying path in the conveying direction, A perforating means having a punch for perforating the sheet being conveyed by the conveying means and an opening that defines an opening through which the sheet passes, wherein the opening is the end of the opening in the width direction perpendicular to the conveying direction and includes an end of the opening facing the sheet in the width direction when the sheet is positioned in the opening, A moving means for moving the drilling means in the width direction, A detection means provided upstream of the punch in the transport direction for detecting a first transport position, which is the position of the sheet in the width direction, A control means that acquires size information of the sheet, determines a second transport position which is the position of the sheet in the width direction when the sheet is transported by the transport means based on the size information, and controls whether or not to perform an avoidance process that moves the punching means so that the punch and the opening end move away from the sheet in the width direction based on the first transport position and the second transport position, A sheet processing device equipped with the following features.

2. The detection means detects the position in the width direction of one of the two ends of the sheet as the first transport position, The sheet processing apparatus according to claim 1, wherein the control means determines the position of the first end in the width direction when the sheet is conveyed by the conveying means based on the size indicated by the size information as the second conveying position.

3. The sheet processing apparatus according to claim 1 or 2, wherein the control means executes the avoidance process when the difference between the first transport position and the second transport position is greater than a threshold.

4. The sheet processing apparatus according to claim 3, wherein the threshold value is a value smaller than the sum of a predetermined value and the distance in the width direction of the perforating means that can be moved by the moving means while the sheet is being transported from the position in the transport direction in which the detection means detects the first transport position to the position in the transport direction in which the perforating means perforates the sheet.

5. A conveying means for conveying a sheet along a conveying path in the conveying direction, A perforating means having a punch for perforating the sheet being conveyed by the conveying means and an opening that defines an opening through which the sheet passes, wherein the opening is the end of the opening in the width direction perpendicular to the conveying direction and includes an end of the opening facing the sheet in the width direction when the sheet is positioned in the opening, A moving means for moving the drilling means in the width direction, A detection means provided on the upstream side of the punch in the conveying direction for detecting the sheet length, which is the length of the sheet in the conveying direction, A control means that determines a first transport position, which is the position of the sheet in the width direction, based on the sheet length, obtains size information of the sheet, determines a second transport position, which is the position of the sheet in the width direction when the sheet is transported by the transport means, based on the size information, and controls whether or not to perform an avoidance process to move the punching means so that the punch and the opening end move away from the sheet in the width direction, based on the first transport position and the second transport position. A sheet processing device equipped with the following features.

6. The sheet processing apparatus according to claim 5, wherein the control means determines the position in the width direction of one of the two ends of the sheet when the sheet is conveyed by the conveying means based on the size determined from the sheet length, and determines the position in the width direction of the first end when the sheet is conveyed by the conveying means based on the size indicated by the size information, as the second conveying position.

7. The sheet processing apparatus according to claim 5 or 6, wherein the control means executes the avoidance process when the difference between the first transport position and the second transport position is greater than a threshold.

8. The sheet processing apparatus according to claim 7, wherein the threshold value is less than half the difference between the maximum and minimum values ​​of the length in the width direction of a plurality of sizes of sheets available in the sheet processing apparatus.

9. The sheet processing apparatus according to any one of claims 1 to 8, wherein the timing at which the first transport position is detected or determined is later than the timing at which the control means determines the second transport position.

10. When the control means determines the second transport position, it moves the drilling means from the home position to a standby position corresponding to the second transport position. The sheet processing apparatus according to any one of claims 1 to 9, wherein the standby position is a position closer to the transport path than the home position.

11. The sheet processing apparatus according to claim 10, wherein the control means moves the perforating means from the standby position toward the home position when the avoidance process is executed.

12. The sheet processing apparatus according to any one of claims 1 to 11, wherein the control means causes the perforating means to perforate the sheet if the avoidance process is not performed.

13. The sheet processing apparatus according to any one of claims 1 to 12, wherein the size information is information set by the user or information received from an external device of the sheet processing apparatus.

14. The sheet processing apparatus according to any one of claims 1 to 13, wherein in the avoidance process, the perforating means moves such that the punch is located outside the edge of the sheet in the width direction.

15. A sheet processing apparatus according to any one of claims 1 to 4, An image forming means for forming an image on a sheet conveyed by the aforementioned conveying means, An image forming apparatus equipped with the following features.

16. The image forming apparatus according to claim 15, wherein the detection means and the perforation means are provided downstream of the transport path from the image forming means.

17. A sheet processing apparatus according to any one of claims 5 to 8, An image forming means for forming an image on a sheet conveyed by the aforementioned conveying means, An image forming apparatus equipped with the following features.

18. The detection means is provided upstream of the transport path from the image forming means, The image forming apparatus according to claim 17, wherein the perforating means is provided downstream of the transport path from the image forming means.

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