JP2017165562A - Sheet processing device, sheet processing method, and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet processing device and a sheet processing method, capable of surely drilling a plurality of punch holes on a sheet with high quality at always.SOLUTION: An image formation system includes, in a sheet post-processing device, a drilling device which includes a plurality of punch members 40 that reciprocate in axial direction through a rack member 43 that reciprocates linearly by a drive motor 42, for drilling a sheet that is delivered into a drilling process position from an image formation device. A control part detects position and moving direction of the rack member with an output of a position sensor that detects a flag provided at the rack member, and detects rotation of the drive motor by an encoder 69. After all the punch members 40 come into a home position from a work position, a sheet having been drilled is transported from the drilling process position when the drive motor is rotated by a specified number of pulses.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sheet processing apparatus and sheet processing method for automatically punching files or other punch holes in various sheet-like workpieces such as paper sheets, plastic sheets, metal sheets, cloth sheets, and the like. The present invention relates to an image forming apparatus provided with such a sheet processing apparatus.

  Conventionally, for example, a binding hole for a file is automatically provided on a sheet such as a paper sheet that is mounted on an image forming apparatus such as a copying machine, a printing machine, a facsimile machine, a post-processing apparatus, or a bookbinding apparatus. A drilling device for drilling is used. For example, there is known a perforating apparatus that perforates a plurality of punch holes in a sheet by reciprocating up and down a plurality of punch members having a perforating blade at the tip in a perforating direction with a drive motor (for example, see Patent Document 1). reference).

  The punching device of Patent Document 1 linearly reciprocates a common gear transmission member composed of a rack meshing with a pinion of a common drive motor, and drives each punch member having a passive gear meshing with the gear transmission member. Transmits the rotation of the motor and executes the punching operation. Each punch member descends in the axial direction while rotating from the standby position of the top dead center, enters the punching area where the sheet is placed, punches up, returns upward from the bottom dead center, returns to the standby position, and performs the punching operation. finish.

  In addition, a paper punching device and a paper processing device are known that have good stop accuracy of the drive motor so as not to cause problems in paper transport after punching, are small and capable of high-speed processing, and are low in cost (for example, (See Patent Document 2). The paper processing apparatus of Patent Document 2 detects the position of the punch blade and checks for overrun when the motor driving operation for performing the first punching operation stops or before stopping, and the deviation from the desired position is detected. In some cases, the motor is re-driven to approach the desired position.

JP 2012-86290 A JP 2005-75550 A

  In Patent Document 2, it is safe to start the conveyance of the punched paper until the drive motor that performs the punching operation stops, and after the punch blade enters the home position, the drive motor is stopped. Previously, it has been described that even if the conveyance of the punched paper is started, there is no problem that the edge of the paper or the punch hole is caught by the punch blade. That the punch blade has entered the home position is detected by the home position sensor detecting the notch of the home position filler mounted on the shaft of the crank gear rotated by the drive motor.

  In general, various mechanical loads due to friction between the outer peripheral surface of the punch member and the periphery of the punch hole, friction between the blade edge and the die hole, the thickness, material, and properties of the sheet act on the punch member during the punching operation. Further, the drive motor may have variations in characteristics of the motor itself and variations in motor drive voltage. In these cases, even if the drive motor is braked at the same timing, there is a possibility that the stop positions of the drive motor and the punch member are greatly fluctuated and their moving speeds are made slower.

  In the prior art, as described in Patent Document 2, it is customary not to directly detect each punch member or its cutting edge with a position sensor, so the punch member stops or moves slowly near the boundary of the home position. In this case, even if the position sensor detects the home position, the cutting edge of the punch member may actually protrude into the perforated region. If the perforated sheet is conveyed in this state, problems such as jamming (paper jam) occur due to being caught by the perforating blade and damaging punch holes or the sheet.

Accordingly, the present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a sheet processing apparatus and sheet processing capable of always punching a plurality of punch holes in a sheet with high quality and reliability. It is to provide a method.
Another object of the present invention is to provide an image forming apparatus provided with such a sheet processing apparatus.

In order to achieve the above object, the sheet processing apparatus of the present invention provides
A sheet conveying unit that conveys the punched sheet from a predetermined processing position;
A plurality of punch members that reciprocate between a standby position and a punching position to punch a sheet at a predetermined processing position;
A common drive motor for reciprocating a plurality of punch members between a standby position and a punching position;
A control unit for controlling the sheet conveying unit,
The control unit determines that all of the plurality of punch members are in the standby position, and when the driving motor rotates by a predetermined rotation amount based on the determination, the sheet is conveyed so as to convey the punched sheet from the predetermined processing position. The conveyance unit is controlled.

  As described above, the control unit controls the sheet conveying unit, so that the punched sheet can be conveyed from a predetermined processing position in a state where all punch members are always in the standby position after the punching operation. As a result, a plurality of punch holes can be reliably punched with high quality in the sheet, and the required time from punching to conveyance of the sheet can be shortened, so that productivity can be improved.

  In one embodiment, an encoder for detecting the rotation amount of the drive motor is further provided, and the control unit detects the predetermined rotation amount based on the number of output pulses of the encoder, so that the perforation is performed regardless of the rotation speed of the drive motor. It is possible to more accurately determine and control the timing at which the processed sheet is conveyed from a predetermined processing position.

  In another embodiment, the driving unit further includes a common driving force transmission member that moves the plurality of punch members to reciprocate between the standby position and the punching position by rotation of the drive motor, and the control unit includes the plurality of punch members. It is determined from the position of the driving force transmission member that all the members are in the standby position. As a result, it is possible to more easily and reliably detect the timing for conveying the punched sheet from the predetermined processing position and its starting point.

  In another embodiment, the detector further includes a detector that moves integrally with the driving force transmission member, and a sensor that detects and outputs the detector, and the control unit is configured to output a plurality of punch members based on the output of the sensor. It is determined that everything is in the standby position. With such a simple configuration, it is possible to more accurately detect the starting point of the timing at which the punched sheet is conveyed from the predetermined processing position.

  In another embodiment, the punch member is in the standby position and the punching position in the forward stroke in which the driving force transmission member linearly moves in either direction and in the backward stroke in which the driving force transmission member moves in the opposite direction after the forward stroke, respectively. A plurality of detectors so that the control unit can determine that all of the plurality of punch members are in the standby position after punching the sheet in each of the forward and backward strokes. Is provided. As a result, punch holes can be punched continuously and with high quality in a plurality of sheets, and the time required from punching to transporting a sheet can be shortened with a single punching operation, so that productivity can be improved. it can.

According to another aspect of the present invention, a sheet conveying unit that conveys a punched sheet from a predetermined processing position and a standby position and a punching position are reciprocated to punch a sheet at the predetermined processing position. A sheet processing method using a plurality of punch members, and a common drive motor for reciprocating the plurality of punch members between a standby position and a punching position,
It is determined that all of the plurality of punch members are in the standby position, and when the drive motor rotates by a predetermined amount of rotation based on the determination, the sheet conveying unit is controlled to convey the punched sheet from the predetermined processing position. A sheet processing method is provided.

  By controlling the sheet conveying unit in this way, it is possible to convey the punched sheet from a predetermined processing position in a state where all the punch members are always in the standby position after the punching operation. As a result, a plurality of punch holes can be reliably punched with high quality in the sheet, and the time required from the punching of the sheet to its conveyance can be shortened to improve productivity.

  In an embodiment, the rotation amount of the drive motor is detected using an encoder, and the predetermined rotation amount is detected based on the number of output pulses of the encoder, so that the punched sheet is formed regardless of the rotation speed of the drive motor. It is possible to more accurately determine and control the timing of conveyance from a predetermined processing position.

  In another embodiment, a plurality of punch members are reciprocated between a standby position and a punching position using a common driving force transmission member that is moved by rotation of a drive motor, and all of the plurality of punch members are in a standby position. Is determined from the position of the driving force transmission member. As a result, it is possible to more easily and reliably detect the timing for conveying the punched sheet from the predetermined processing position and its starting point.

  In another embodiment, the predetermined motor is braked before all of the plurality of punch members enter the standby position so as to stop after rotating beyond the predetermined rotation amount. In addition to ensuring the amount of rotation, it is possible to stop the drive motor and the punch member earlier in preparation for the next drilling operation, thereby increasing the productivity.

  According to another aspect of the present invention, the sheet processing apparatus of the present invention described above is provided, whereby a plurality of punch holes can be reliably punched in the sheet after image formation, and high productivity is achieved. An image forming apparatus is provided.

FIG. 4A is an overall configuration diagram of an image forming apparatus and a sheet post-processing apparatus according to the present invention, and FIG. 4B is a partial configuration diagram of the sheet post-processing apparatus. FIG. 2 is a front view of the punching device of FIG. 1. Sectional drawing in the III-III line of the punching apparatus of FIG. The expansion perspective view which shows a punch member from the front side. (A)-(d) figure is explanatory drawing which shows continuously the punching operation | movement of a punch member. The expanded view of the cylindrical cam of each punch member. (A) The figure is an expanded sectional view of the position detection mechanism of a rack member, (b) A figure is a partial front view of a flag member, (c) A figure is a partial top view of a flag member. FIG. 6 is a diagram illustrating an output signal of a position sensor related to a flag position and a sheet conveyance timing. The block diagram which shows the control structure of the sheet | seat post-processing apparatus of FIG. 6 is a timing chart illustrating sheet conveyance control.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the accompanying drawings, similar components are denoted by the same reference numerals throughout the present specification.

  FIG. 1A schematically shows an overall configuration of an image forming system including a punching device according to the present invention. As shown in the figure, the image forming system according to the present embodiment includes an image forming apparatus A that sequentially prints and discharges sheets, and a sheet post-processing apparatus B that is provided on the downstream side in the sheet discharging direction. The The sheet post-processing apparatus B includes a punching device C.

  The image forming apparatus A according to the present embodiment is a copying machine using an electrostatic printing process, and includes an image forming unit A1, a scanner unit A2, and a feeder unit A3. The present invention can be applied to image forming apparatuses having various structures such as a printer and a printing machine.

  The image forming unit A1 includes a paper feed unit 2, an image forming unit 3, a paper discharge unit 4, and a control unit (not shown) inside the housing 1. The sheet feeding unit 2 is provided with a plurality of sheet cassettes 5, and the sheet having the size and direction designated by the control unit is fed out to the sheet feeding path 6. The sheet fed to the sheet feeding path 6 is fed to the downstream image forming unit 3 at a predetermined timing after the leading edge position is aligned by the registration roller 7.

  In the image forming unit 3, for example, a toner ink is attached to a latent image formed on the electrostatic drum 10 by a head 9 composed of a laser light emitter by a developing unit 11, and an image transferred onto a sheet by a transfer charger 12 is fixed to a fixing roller. 13 to fix. In the paper discharge unit 4, a paper discharge path 16 in which a paper discharge port 14 and a paper discharge roller 15 that are opened in the casing 1 are arranged, and a sheet fed back in a switchback manner from the paper discharge path are reversed, and the registration roller is again turned on. A circulation path 17 for forming an image on the back side of the sheet by feeding to 7- is arranged in parallel. The sheet on which the image forming unit 3 forms an image on one side or both sides is carried out from the sheet discharge port 14 to the sheet post-processing apparatus B by the sheet discharge roller 15.

  The scanner unit A2 photoelectrically converts a platen 21 on which a document sheet is placed, a carriage 22 that reciprocates along the platen to scan an image of the document sheet, and reflected light from the document on the platen 21 by the carriage. And an optical reading unit 23 for outputting to the image forming unit 3. A document sheet is automatically fed to the platen 21 from a feeder unit A3 disposed on the scanner unit A2.

  As shown in FIG. 1B, the sheet post-processing apparatus B aligns the carry-in port 27 of the housing 26 with the paper discharge port 14 in order to introduce the sheet from the paper discharge port 14 of the image forming apparatus A. Be placed. The housing 26 is provided with a sheet carry-in path 28 for conveying the sheet from the carry-in entrance 27 and a paper discharge stacker 29 for stacking the sheets carried out from the sheet carry-in path.

  In the sheet carry-in path 28, the punching device C is arranged, and a pair of carry-in rollers 30 is provided on the upstream side, and a pair of conveyance rollers 31 that can be rotated forward and backward are provided on the downstream side. Further, the sheet carry-in path 28 is provided with a sheet rear end aligning portion 33 immediately downstream of the carry-in roller pair 30, and is carried into the sheet carry-in path 28 between the sheet rear end aligning portion and the punching device C. A sheet detection sensor 34 that detects the trailing edge of the sheet is disposed.

  When the trailing edge of the sheet conveyed through the sheet carry-in path 28 by the conveyance roller pair 31 is detected by the sheet detection sensor 34, the control unit reverses the conveyance roller pair 31 to switch back the sheet. . When the trailing edge of the sheet that is reversed and fed back through the sheet carry-in path 28 abuts against the sheet trailing edge aligning portion 33 and is aligned, the conveying roller pair 31 is stopped.

  As a result, the sheet S is held at a predetermined perforation processing position with respect to the perforation apparatus C by the conveying roller pair 31 in a state where the rear end is aligned with the rear end alignment unit 33 and positioned as illustrated. . The control unit operates the punching device C to punch a desired number of punch holes at predetermined positions on the sheet S.

  FIG. 2 schematically shows the entire configuration of the punching device C. As will be described later, the punching device C of this embodiment includes four punch members in order to automatically punch two or four holes in the sheet. Of course, the present invention can be similarly applied to a punching device having a structure including two, three, five or more punch members.

  As shown in the figure, the punching device C includes four punch members 40, a device frame 41 for mounting and supporting the punch members 40, a common drive motor 42 for driving the punch members, and the rotation of the drive motor for the punch members. As a common driving force transmission member that transmits to the rack, a rack member 43 that extends linearly in the longitudinal direction is provided. The drive control of the drive motor is performed by a control unit provided in the sheet post-processing apparatus B, as will be described later.

  The device frame 41 includes an upper frame 44 and a lower frame 45 that extend in parallel to the longitudinal direction. 3, the upper frame 44 includes a horizontal upper plate portion 48, an intermediate plate portion 49 extending vertically downward from one end portion of the upper plate portion, and a lower end of the intermediate plate portion. A lower plate portion 50 having a substantially L-shaped cross section extends at a right angle in parallel with the upper plate portion 48.

  The lower frame 45 defines a sheet support surface 45a for supporting a sheet to be punched by its horizontal and flat upper surface. The lower frame 45 is arranged so that a certain slight gap 51 is defined between the seat support surface 45a and the horizontal lower surface of the lower plate portion 50 over substantially the entire length thereof, and both ends in the longitudinal direction thereof. And are integrally coupled to the upper frame 44. The gap 51 forms a sheet path for placing a sheet carried from the image forming apparatus A into the sheet post-processing apparatus B at a predetermined punching processing position, and the sheet is supported by the sheet support surface 45a in the gap. A punch hole is drilled.

  In the upper frame 44, four punch members 40 (40a to 40d) are arranged in a straight line along the longitudinal direction at a predetermined interval, for example, corresponding to the interval of the file holes set by a predetermined standard. ing. As shown in FIG. 3, each punch member 40 is formed of a circular rod-shaped member extending in the vertical direction in the drawing and having a substantially constant diameter over the entire length, and has a cylindrical perforated blade 53 formed at the lower end thereof. . The perforation blade 53 is formed so as to cut out the cylindrical peripheral edge of the punch member 40 in a V shape when viewed from the side, that is, to define a V-shaped cutout at a certain facing side surface position of the cylindrical peripheral edge. Is formed.

  In the upper frame 44, guide holes 44a and 44b are formed so as to penetrate the upper plate portion 48 and the lower plate portion 50, respectively, at positions facing each other in the vertical direction. An upper end portion 46a of the punch member 40 is inserted into the upper guide hole 44a, and a lower end portion 46b thereof is inserted into the lower guide hole 44b so as to be rotatable and slidable in the axial direction. In the lower frame 45, a circular die hole 54 for punching a sheet by the punching blade 41 is provided at a position corresponding to the lower guide hole 44 b of the upper frame 44.

  A cam member 56 formed of a cylindrical cam concentrically with the punch member 40 is integrally attached in the axial direction and the circumferential direction. Further, a driven gear 57 made of a spur gear is integrally attached to the punch member 40 in the axial direction and the circumferential direction below the cam member 56 along the axial direction. The driven gear 57 can be attached to the punch member 40 so as to be integrally rotatable in the circumferential direction and relatively displaceable in the axial direction.

  The cam member 56 has an endless cam groove 60 (60a to 60d) that is recessed over the entire outer periphery thereof. As shown in FIG. 3, a cam pin 61 as a cam follower member that engages with the cam groove 60 is fixed to the intermediate plate portion 49 of the upper frame 44 with a fixing tool such as a screw. The cam pin 61 protrudes horizontally toward the outer peripheral surface of the cam member 56, and is arranged so that the tip of the cam pin 61 is fitted into the cam groove 60 and engages with the upper and / or lower cam surface. The cam pins 54 that engage with the cam grooves 60a to 60d are all arranged at the same height.

  As shown in FIG. 4, the cam groove 60 has a straight portion 62 extending in the circumferential direction at a certain low height position, and rises from the straight portion to a vertex position of a predetermined height at a substantially constant rate. It is comprised from the inclination part 63 descend | falling from the position to the linear part 62 at the same ratio. The apex position of the inclined portion 63 is preferably somewhat curved in order to avoid a sudden change in the cam groove 60.

  5A to 5D show a punching operation when the punch member 40 is rotated in the clockwise direction when viewed from above. When the cam pin 61 is in the linear portion 62 of the cam groove 60, the punch member 40 is held at the top dead center standby position in the axial direction as shown in FIG. The punch member 40 is arranged so that the tip of the punching blade 53 does not protrude into the gap 51 from the lower guide hole 44b at the standby position. As shown in FIG. 5B, when the cam member 56 rotates and the cam pin 61 enters the inclined portion 63 from the straight portion 62 of the cam groove 60, the punch member 40 is lowered downward in the axial direction from the painful position. Then, the punching blade 53 tries to start punching of the sheet S.

  In FIG. 5C, the cam member 56 further rotates, the cam pin 61 rises up the inclined surface of the inclined portion 63 to the vicinity of the apex position, and the punching blade 53 is in a lower position immediately after the sheet S is punched. When the cam pin 61 reaches the apex position of the inclined portion 63, the punch member 40 reaches the punching position at the bottom dead center in the axial direction shown in FIG. 5D, and the punching blade 53 completely penetrates the sheet S. A punch hole is formed.

  When the cam member 56 further rotates and the cam pin 61 exceeds the apex position of the inclined portion 63, the punch member 40 rises upward in the axial direction from the bottom dead center. When the cam pin 61 enters the linear portion 62 from the downward inclined surface of the inclined portion 63, the punch member 40 returns to the standby position in FIG. 5A and stops moving in the axial direction. When the rotation of the cam member 56 is temporarily stopped at this position and then rotated counterclockwise, the punch member 40 rotates in the direction opposite to that shown in FIGS. ) To (d), the sheet S is punched. Thus, the rotation operation of the punch member 40 is converted into a linear reciprocation operation in the axial direction by the engagement of the cam groove 60 and the cam pin 61.

  As described above, the rack member 43 that transmits the rotation of the drive motor 42 to all the punch members 40a to 40d has the teeth 58 that mesh with the driven gears 57 of the punch members, as shown in FIGS. Have. The tooth portion 58 is formed on the side surface of the rack member 43 on the punch member side so as to extend substantially along the longitudinal direction.

  As shown in FIG. 3, the rack member 43 has its upper side portion regulated in the vertical direction by the base end portion 61a of the cam pin 61 and its lower side portion by the upper surface of the lower plate portion 50 of the upper frame 44. The driven gear 57 and the intermediate plate portion 49 of the upper frame 44 are regulated in the front-rear direction. Thereby, the rack member 43 can reciprocate all the punch members 40a to 40d linearly along the longitudinal direction while meshing the teeth 58 with the passive gear 57. Each of the punch members 40 a to 40 d rotates by a predetermined angle according to the movement amount of the rack member 43.

  As shown in FIG. 2, the drive motor 42 for reciprocating the rack member 43 in the longitudinal direction is fixed to the lower left end portion of the upper frame 44 with a bracket 59. A drive gear 66 is attached to the upper end of the rotation shaft 65 of the drive motor 42 and is connected to the tooth portion 58 of the rack member 43 via an intermediate reduction gear train 67 that meshes with the drive gear. Thereby, the rotation of the drive motor 42 is decelerated and transmitted to the rack member 43, and the rack member can be linearly moved in either direction according to the rotation direction of the drive motor.

  The drive motor 42 is provided with an encoder 69 in order to detect the amount of rotation. The encoder 69 is an optically transmissive type that includes a code wheel 70 that is mounted on the lower end of the rotary shaft 65 so as to be integrally rotatable, and a sensor unit 71 that has a light projecting unit and a light receiving unit that are disposed to face each other with the code wheel interposed therebetween. is there. Thereby, the rotation direction and rotation speed of the drive motor 42 can be controlled with higher accuracy in association with the punching timing of the punch members 40a to 40d, for example.

  FIG. 6 is a development view of the cam grooves 60a to 60d of the punch members 40a to 40d. As shown in FIG. 2, in the first punch member 40a at the left end in FIG. 2, the cam groove 60a has one linear portion 62a and one inclined portion 63a. The cam groove 60b of the second punch member 40b that is the second from the left has two inclined portions 63b1 and 63b2 and two linear portions 62b1 and 62b2 that connect them. Similar to the second punch member 40b, the cam groove 60c of the third punch member 40c third from the left has two inclined portions 63c1 and 63c2 and two linear portions 62c1 and 62c2 connecting them. . The cam groove 60d of the fourth punch member 40d at the right end has one linear portion 62d and one inclined portion 63d, like the first punch member 40a.

  In FIG. 6, the inclined portions 63a, 63b1, 63c1, and 63d of the first to fourth punch members 40a to 40d described in the left part are used for punching four holes in the sheet. The inclined portions 63b2 and 63c2 of the second and third punch members 40b and 40c described in the right part of the figure are used for punching two holes in the sheet.

  The cam pins 61 that engage with the cam grooves 60a to 60d are all provided at the same angular position, whereas the apex positions of the inclined portions are arranged with a slight phase difference. The inclined portions 63a, 63b1, 63c1, and 63d for drilling the four holes are arranged such that the vertex positions 63pa, 63pb1, 63pc1, and 63pd are sequentially shifted in phase by a predetermined angle Δα along the circumferential direction. Similarly, in the inclined portions 63b2 and 63c2 for drilling two holes, the vertex positions 63pb2 and 63pc2 are sequentially shifted in phase by a predetermined angle Δβ along the circumferential direction. The predetermined angle Δα and the predetermined angle Δβ may be the same or different values.

  The straight portions 62a to 62d of the respective cam grooves are formed at the same height position, and the inclined portions 63a, 63b1, 63b2, 63c1, 63c2, and 63d are formed in the same shape and size. The cam pins 61 that engage with the respective cam grooves are arranged at the same angular position and the same height position as described above. Therefore, when the punch members 40a to 40d are rotated, the punch members 40a to 40d move by the same amount along the axial direction except that a time difference due to the phase difference is generated.

  By providing the phase difference in this manner, four or two punch holes are formed in the sheet with the timing slightly shifted. Thereby, when simultaneously punching a sheet with a plurality of punch members 40, the load applied to the drive motor 42 common to all the punch members can be reduced.

  In the punching apparatus of this embodiment, the cam grooves 60a to 60d of the respective punch members 40a to 40d are provided with the phase differences Δα and Δβ so as to form the inclined portion, so that it is possible to drill four holes or two holes. Some time lag occurs after the first punch member finishes punching and the last punch member finishes punching and returns to the standby position. Therefore, in the present embodiment, until the last punch member completely punches the sheet S and returns to the standby position, the rack member 43 is continuously moved and all the punch members are stopped at the standby position. The rotation and braking of the drive motor 42 are controlled.

  As shown in FIG. 6, the cam grooves 60 a to 60 d have three angle ranges in which the straight portions of all the punch members 40 a to 40 d overlap at the same time. In the present embodiment, the three angular ranges are referred to as first to third home positions Hp1 to Hp3. In the first to third home positions, all punch members 40a to 40d are in the standby position of the top dead center and are waiting for the next punching operation. On the other hand, in the two angular ranges between the first home position Hp1 located at the center and the second and third home positions Hp2 and Hp3 located at both left and right ends in the figure, at least one punch member 40 is in the standby position. In this embodiment, these are referred to as first and second operation positions Op1 and Op2.

  In the present embodiment, the position in the longitudinal direction where the rack member 43 stops as an initialization operation when the punching device C is activated is set as the reference position, and the reference position PR of the cam groove 60 corresponding thereto is set as the first position as shown in FIG. Set in the home position Hp1. Therefore, the rotational positions of the punch members 40 and the cam grooves 60 can be determined by setting the angular position of the reference position PR to 0 ° and associating the rotational direction with the movement direction of the rack member 43 in the longitudinal direction.

  When the rack member 43 moves in the longitudinal direction from the reference position to the right side in FIG. 2 and the punch members 40a to 40d rotate clockwise from the first home position Hp1 in plan view, the cam pin 61 is 6 moves to the right side and enters the first operation position Op1 of the cam grooves 60a to 60d, and a two-hole drilling operation is performed. The punch member is further rotated in the clockwise direction so that the cam pin 61 stops within the second home position Hp2 to stop the movement of the rack member 43, thereby completing the drilling operation of the two holes.

  When the rack member 43 moves from the stop position to the left in FIG. 2 in the longitudinal direction and the punch members 40a to 40d rotate counterclockwise from the second home position Hp2, the cam pin 61 moves to the left in FIG. Then, the cam groove 60a-60d enters the first operating position Op1, and the next two holes are drilled. Similarly, the punch member further rotates counterclockwise so that the cam pin 61 stops within the first home position Hp1, thereby stopping the movement of the rack member 43. When the rack member 43 is reciprocated between the first home position HP1 and the second home position HP2 from the reference position in this way, the second and third punch members 40b and 40c are used in both the forward stroke and the backward stroke. The 2-hole punching operation of the sheet is repeatedly executed.

  Conversely, when the rack member 43 moves in the longitudinal direction from the reference position to the left side in FIG. 2 and the punch member rotates counterclockwise from the first home position Hp1, the cam pin 61 moves to the left side in FIG. Then, the cam grooves 60a to 60d enter the second operation position Op2, and a four-hole drilling operation is performed. The punch member is further rotated counterclockwise so that the cam pin 61 stops within the third home position Hp3, and the movement of the rack member 43 is stopped, whereby the four-hole punching operation is completed.

  When the rack member 43 moves from the stop position to the right side in FIG. 2 in the longitudinal direction and the punch members 40a to 40d rotate clockwise from the third home position Hp3, the cam pin 61 moves to the right side in FIG. The cam grooves 60a to 60d enter the second operation position Op2, and the next four holes are drilled. Similarly, the punch member further rotates in the clockwise direction so that the cam pin 61 stops within the first home position Hp1, and the movement of the rack member 43 is stopped. As described above, when the rack member 43 is reciprocated between the first home position HP1 and the third home position HP3 from the reference position, the four holes of the sheet by all the punch members 40a to 40d in both the forward stroke and the backward stroke. The drilling operation is executed repeatedly.

  The punching device C is provided with a rack position detection mechanism 73 for detecting the longitudinal position of the rack member 43, that is, the movement position in the linear direction. As shown in FIGS. 2 and 7A, the rack position detection mechanism 73 has a flag member 74 that is integrally provided on the upper left side of the rack member 58. As shown in FIG. As shown in FIG. 7 (b), the flag member 74 includes first to third flags 75 to 77 protruding vertically upward from the front edge portion, and the front edge portion as shown in FIG. 7 (c). And a fourth flag 78 projecting horizontally forward.

  The first to third flags 75 to 77 each have a substantially rectangular plate-like portion having a predetermined length relatively short in the longitudinal direction of the rack member 43 and having a certain width in a direction perpendicular to the longitudinal direction. The left and right ends thereof have edges perpendicular to the longitudinal direction. Along the longitudinal direction of the flag member 74, a first flag 75 is disposed substantially at the center, and second and third flags 76 and 77 are disposed at predetermined intervals on the left and right ends. As shown in FIG. 7 (c), the fourth flag 78 has an elongated, substantially rectangular shape that has a predetermined length that is relatively long in the longitudinal direction of the rack member 43 and that has a certain width in a direction perpendicular to the longitudinal direction. It consists of a plate-shaped part, and has the edge orthogonal to a longitudinal direction at the both right and left ends, respectively.

  The first to third flags 75 to 77 are set so that the length ranges in the longitudinal direction thereof correspond to the angular ranges of the first to third home positions Hp1 to Hp3 in FIG. The gaps defined between the first flag 75 and the second and third flags 76 and 77 are set so that the length range in the longitudinal direction corresponds to the angular positions of the first and second operating positions Op1 and Op2, respectively. Has been. Accordingly, the left and right edges 75a and 75b of the first flag 75 coincide with the boundary between the first home position Hp1 and the first and second operation positions Op1 and Op2. The right edge 76a of the second flag 76 coincides with the boundary between the second home position Hp2 and the first operating position Op1, and the left edge 77a of the third flag 77 corresponds to the third home position Hp3 and the second operating position Op2. Matches the boundary.

  In the fourth flag 78, the right edge 78a in the drawing is disposed within the range of the first flag 75, and the left edge 78b is disposed within the range of the second flag 76. It extends so as to straddle the two flags 76. Also, as shown in FIGS. 7B and 7C, for the sake of simplicity of description in this specification and the accompanying drawings, when the rack member 43 is in the reference position, the punch member shown in FIG. 40 and the longitudinal position on the flag member 74 corresponding to the reference position PR of the cam groove 60 is expressed as a reference position PR that is the starting point of the movement in the longitudinal direction. In this case, the right edge 78a of the fourth flag 78 is preferably provided so as to coincide with the reference position PR as shown in the figure.

  Furthermore, the rack position detection mechanism 73 includes first to third position sensors 81 to 83 attached to the upper frame 44 via a stay 80 having an L-shaped cross section, as shown in FIG. Each of the position sensors 81 to 83 is a transmission type photosensor having a rectangular box-shaped light projecting unit and light receiving unit that face each other with a predetermined gap therebetween. The position sensor of the present embodiment is turned off when light passes from the light projecting unit to the light receiving unit, and is turned on when the flag passes through the gap between the light projecting unit and the light receiving unit and is blocked. . Conversely, the position sensor can be turned on or off.

  The first position sensor 81 detects the positions of the first to third flags 75 to 77. The first position sensor is preferably configured so that when the rack member 43 is at the reference position, the light projecting and receiving positions of the light projecting unit and the light receiving unit are within the range of the first flag 75, as shown in FIG. As shown in FIG. 4, the arrangement is made to coincide with the reference position PR. Accordingly, in FIG. 6, the output signal of the first position sensor 81 is switched on and off in accordance with the timing when the cam pin 61 crosses the boundary between any one of the home positions and the adjacent work position.

  In order to detect the position of the fourth flag 78, the second position sensor 82 and the third position sensor 83 are located on the left side of the first position sensor 81 along the longitudinal direction, as shown in FIG. Are arranged at predetermined intervals on the left and right. More specifically, as shown in the figure, when the rack member 43 is in the reference position, the third position sensor 83 is positioned so that the second position sensor 82 is positioned approximately at the center of the fourth flag 78 in the longitudinal direction. The fourth flag 78 is arranged so as to coincide with the left edge 78b in the drawing. Accordingly, when the flag member 74, that is, the rack member 43 moves in the longitudinal direction from the reference position PR, the output signal of the third position sensor 83 is switched on and off in accordance with the direction.

  FIG. 8 shows the relationship between the output signal of the rack position detecting mechanism 73 set as described above and the home position and the operating position set by the cam groove 60 of the punch member 40. As shown in the figure, the output of the first position sensor 81 is on when the punch member 40 is in any one of the home positions Hp1 to Hp3, and is off when it is in any of the work positions Op1 and Op2. is there. Therefore, it is determined from the output signal of the first position sensor 81 that the operation state of the punch member 40, that is, the standby position or the drilling operation is in progress, and the transition from the standby position to the drilling operation or the punching operation to the standby position. Transition can be detected.

  The output of the second position sensor 82 is ON when the punch member 40 is within a predetermined range of the first home position Hp1 and the first and second work positions Op1 and Op2 continuous thereto, and the predetermined range is exceeded. It is off when it is within the range of the first and second work positions that have been exceeded and the range of the second and third home positions Hp2 and Hp3 continuous thereto. Therefore, from the output signal of the second position sensor 82, regardless of the 2-hole or 4-hole drilling operation, the movement direction of the punch member 40, that is, the forward or backward stroke of the reciprocating movement around the first home position Hp1. Can be determined.

  The output of the third position sensor 83 is on when the punch member 40 is in a range including the second home position Hp2 from the reference position PR, and is off when the punch member 40 is in a range including the third home position Hp3 from the reference position PR. It is. Therefore, it can be determined from the output signal of the third position sensor 83 whether the punching operation of the punch member 40 is 4 holes or 2 holes.

  When the punch member 40 is at the first home position Hp1, the output signals of the first to third position sensors 81 to 83 are on / on / on or off. In the forward stroke of the two-hole drilling operation, the first position sensor 81 is turned off from the on-off state while the second and third position sensors 82 and 83 are on / off, whereby the punch member 40 is moved to the first home position Hp1. It is detected that the first working position Op1, that is, the two-hole drilling operation has been started. After the output of the second position sensor 82 is switched from ON to OFF, the first position sensor 81 is switched from OFF to ON while the second and third position sensors 82 and 83 are OFF / OFF. It is detected that the member 40 has entered the second home position Hp2, that is, the standby position from the first work position Op1.

  In the reverse stroke of the 2-hole drilling operation, the punch member 40 is moved to the second home position Hp2 by turning the first position sensor 81 from on to off while the second and third position sensors 82 and 83 are turned off / off. From this, it is detected that the first working position Op1, that is, the return 2-hole drilling operation has been started. After the output of the second position sensor 82 is switched from OFF to ON, the first position sensor 81 is switched from OFF to ON while the second and third position sensors 82 and 83 are ON / OFF. It is detected that the member 40 has entered the first home position Hp1, that is, the standby position from the first work position Op1.

  In the forward stroke of the four-hole drilling operation, the first position sensor 81 is switched from on to off while the second and third position sensors 82 and 83 are on / on, so that the punch member 40 is moved to the first home position Hp1. From this, it is detected that the second working position Op2, that is, the four-hole drilling operation has been started. After the output of the second position sensor 82 is switched from on to off, the first position sensor 81 is switched from off to on in the state where the second and third position sensors 82 and 83 are off / on. It is detected that the member 40 has entered the third home position Hp3, that is, the standby position from the second work position Op2.

  In the reverse stroke of the four-hole drilling operation, the punch member 40 is moved to the third home position Hp3 by turning the first position sensor 81 from on to off while the second and third position sensors 82 and 83 are off / on. From this, it is detected that the second work position Op2, that is, the return four-hole drilling operation has been started. After the output of the second position sensor 82 is switched from OFF to ON, the first position sensor 81 is switched from OFF to ON while the second and third position sensors 82 and 83 are ON / ON. It is detected that the member 40 has entered the first home position Hp1, that is, the standby position from the second work position Op2.

  By detecting the output signals of the first to third position sensors 81 to 83 in this way, the position of the punch member 40, the rotation direction, the operating state, the transition timing between each home position and the work position, etc. are determined. Can be detected. The rotation of the punch member 40 is caused by the movement of the rack member 43 in the longitudinal direction through the gear mechanism including the driven gear 57 and the tooth portion 58 and the cam mechanism including the cam member 56 and the cam pin 61, and the rack member and the tooth portion. 58, and the rotation of the drive motor 42 through a gear mechanism including the intermediate gear train 67 and the drive gear 66. Therefore, by controlling the rotation of the drive motor 42 based on the output signals of the first to third position sensors 81 to 83, the punching operation of the punch member 40 can be controlled centrally.

  FIG. 9 schematically shows a control configuration of the sheet post-processing apparatus B of the present embodiment. The sheet post-processing apparatus B includes a control unit 87 for controlling the sheet punching operation. The control unit 87 includes a CPU 88 that controls the drive voltage applied to the drive motor 42, and a memory 89 that stores information and data necessary for the punching process and its control. In another embodiment, the control unit 87 can be provided on the main body side of the image forming apparatus A or the like in which the punching device C is incorporated or the sheet post-processing device B is provided.

  The controller 87 is connected to a motor drive circuit 91 connected between the drive motor 42 and its power supply 90, an encoder 69, and first to third position sensors 81 to 83. The motor drive circuit 91 is provided with a short circuit (short brake circuit) having an appropriate resistance between the terminals of the motor in order to quickly stop the rotation of the drive motor 42. Further, a main body control unit 92 provided in the image forming apparatus A is connected to the control unit 87. The control unit 87 sends information (sheet size, number of sheets, number of punch holes to be punched, sheet material / thickness, etc.) necessary for performing punching processing to the sheet conveyed from the image forming apparatus A. Can be obtained from

  FIG. 10 is a timing chart for explaining the control of the drive motor 42 in the forward stroke of the 4-hole drilling operation. In the figure, the horizontal axis represents time, and the vertical axis represents the current value. A line L1 indicates a change in the motor drive current from when the drive motor 42 is rotated to perform a four-hole drilling operation until the drive motor is braked and stopped after the drilling. A line L2 is an output signal of the first position sensor 81, crosses the edge 75b of the first flag 75 at the time t1, enters the second work position Op2 from the first home position Hp1, and the third flag 77 at the time t2. It represents entering the third home position Hp3 from the second work position Op2 beyond the edge 77a. A line L3 is a pulse signal output from the encoder 69 of the drive motor.

  On the line L1, when the drive motor 42 is started at time t0, the first punch member 40a starts to rotate from the standby position of the first home position Hp1, enters the second work position Op2 at time t1, and descends in the axial direction. At the time t3, the tip of the punching blade 53 comes into contact with the upper surface of the sheet and punching is started. After a predetermined drilling time has elapsed from time t1, the punch member 40a finishes the punching operation, moves to the standby position of the third home position Hp3, and stops when the drive motor 42 stops.

  Each of the other three punch members 40b to 40d also enters the second work position Op2 from the first home position Hp1 with a phase difference Δα in order following the first punch member 40a, and performs a punching operation. It moves to the position Hp3 and stops when the drive motor 42 stops. As will be described later, the drive motor 42 brakes by applying the short brake at a time tbr before the last punch member 40d reaches the third home position Hp3. The brake-driving drive motor 42 rotates by inertia and stops completely in a state where all the punch members are at the third home position Hp3.

  The punched sheet is transported from the punching processing position of the punching device C toward the paper discharge stacker 29 by causing the transport roller pair 31 to rotate forward. In another embodiment, the sheet can be transported to another processing unit included in the sheet post-processing apparatus B or another sheet processing apparatus connected to the sheet post-processing apparatus B.

  From the viewpoint of preventing the sheet from touching the punching blade 53 in the gap 51, that is, the punching region, from being damaged or causing jamming, all the punch members 40 are completely at the third home position Hp3. It is safest to do it after stopping. On the other hand, in order to shorten the processing time required for a series of steps of carrying in, punching, and transporting the sheet and increase the production efficiency, if it is confirmed that the punching blade 53 does not exist in the punching region, the drive motor 42 is Even if the sheet is still rotating or the punch member 40 is still moving, the sheet can be conveyed by rotating the conveying roller pair 31.

  When the drive motor 42 is completely stopped, it is preferable that the punch member 40 always stops at the substantially same position and sufficiently enters the home position. However, the punch member 40 actually has various sizes due to friction between the outer peripheral surface and the periphery of the punch hole, friction between the punching blade 53 and the die hole 54, the thickness, material, and properties of the sheet. Different mechanical loads act. Further, the drive motor 42 may have variations in characteristics of the motor itself, variations in motor drive voltage, miscounting of pulse signals for operating the short brake, and the like.

  Due to these factors, the stop positions of the drive motor 42 and the punch member 40 may fluctuate greatly even if braking is performed at the same timing. Furthermore, the moving speed of the drive motor 42 and the punch member 40 after braking decreases with the passage of time. If the punch member 40 stops near the boundary between the work position and the home position or moves slowly, even if the position sensor detects the flag, a part of the punching blade 53 is in the drilling region. There is a risk of remaining or protruding. In such a state, when the punched sheet is transported from the punching processing position or the next sheet is carried in, it is caught by the punching blade 53, and punch holes or sheets are damaged, jammed (paper jam), or the like.

  In the present embodiment, when the third position sensor 83 detects that the last punch member 40d has entered the third home position Hp3, when the drive motor 42 has rotated by a predetermined amount of rotation from that point, the controller 87 Then, the conveyance roller 31 pair is rotated forward. Thus, the punched sheet S is conveyed from the punching processing position toward the paper discharge stacker 29 without reliably contacting or catching the punching blade 43 of the punch member 40.

  The predetermined rotation amount of the drive motor 42 can be set by the number of output pulses of the encoder 69. The controller 87 starts the pulse count of the encoder 69 when the output signal of the third position sensor 83 is turned on from off, and operates the pair of transport rollers 31 when the predetermined number of output pulses ΔNid is reached. Thereby, in addition to and in cooperation with the drive control of the drive motor 42, the sheet transport control of the pair of transport rollers 31 can be managed centrally based on the number of output pulses of the encoder. In another embodiment, the predetermined rotation amount can be set according to the rotation angle or the rotation time of the drive motor 42.

  The predetermined output pulse number ΔNid is preferably set to a relatively small number of pulses, for example, several pulses. Thus, the conveyance of the sheet S can be started in a relatively short time after the punch member 40 enters the third home position Hp3 in a state where the punching blade 53 does not remain or protrude in the punching area. Therefore, the next sheet can be carried into the punching processing position earlier to prepare for the next punching process. As a result, it is possible to efficiently perform punching processing of sheets sequentially fed from the image forming apparatus A at a higher speed.

  The time tbr when the drive motor 42 is braked can be determined by calculating backward from the desired stop position based on the inertial rotation amount until the time ts when the drive motor stops after braking. This inertial rotation amount is also preferably determined by the number of output pulses of the encoder 69 in accordance with the predetermined rotation amount. The number of output pulses Nid of the encoder 69 corresponding to the inertial rotation amount of the drive motor 42 can be obtained, for example, from data such as a repeated test or a calculation result in advance. In another embodiment, the inertial rotation amount can be determined by the rotation angle or rotation time of the drive motor 42.

  The time tbr can be set based on the number of output pulses of the encoder 69 that is the amount of rotation of the drive motor 42. The control unit 87 starts pulse counting of the encoder from time t1 when the output of the first position sensor 81 switches from on to off, and connects the short brake circuit when a predetermined number of output pulses Nbr is reached. The predetermined number of output pulses Nbr is set based on data such as a repetitive test or a calculation result in advance, for example. Thereby, the braking timing of the drive motor 42 can be determined accurately.

  The above-described sheet conveyance control can be applied not only to the forward stroke of the 4-hole punching operation but also to the return stroke and the reciprocating stroke of the 2-hole punching operation. Hereinafter, control by the control unit 87 related to sheet punching and conveyance and driving of the drive motor 42 in the reciprocating process of the 4-hole and 2-hole punching operations will be described with reference to FIG.

  When the sheet post-processing apparatus B and the punching apparatus C are activated, the control unit 87 performs an initialization operation so that the drive motor 42 and the rack member 43, that is, the flag member 74 stand by at the reference position PR. As a result, the drive motor 42 can start from the reference position PR and continuously execute the reciprocating strokes of the 4-hole and 2-hole drilling operations as shown in the lower part of FIG. Note that the rotational speed n of the drive motor 42 is expressed by a constant value in FIG. 8 for the sake of simplifying the drawing during the drilling operation until braking, but actually, as described above, the punch member 4 and Needless to say, the perforation blade 53 is somewhat lowered by the mechanical load due to the resistance received from the sheet, the friction with the punch hole, or the like.

  In the forward stroke of the four-hole drilling operation, the controller 87 activates the drive motor 42 to rotate it counterclockwise, and moves the rack member 43 to the left in FIG. 2 along the longitudinal direction. When the output of the first position sensor 81 changes from on to off, the controller 87 starts the pulse count of the encoder 69. When the number of output pulses of the encoder 69 reaches a preset number of braking pulses Nbr11, the control unit 87 connects the short circuit of the motor drive circuit 91 and applies a short brake to the drive motor 42.

  Thereafter, when the drive motor 42 rotates by inertia, the rack member 43 enters the third home position Hp3, and the first position sensor 81 detects the edge 77a of the third flag 77 and changes from off to on, the controller 87 Starts the pulse count of the encoder 69. When the number of output pulses of the encoder reaches a preset sheet conveyance pulse number ΔNid11, the control unit 87 operates the pair of conveyance rollers 31 to convey the punched sheet from the punching processing position.

  The rack member 43 further moves due to inertial rotation of the drive motor 42 and stops at the position Ps1 in the third home position Hp3. When the backward movement of the four-hole punching operation is performed after the conveyance of the sheet, the control unit 87 operates the pair of conveyance rollers 31 to carry in the next sheet, and positions and holds the next sheet at the punching processing position.

  In the backward stroke of the four-hole drilling operation, the control unit 87 starts the drive motor 42 from the state where the rack member 43 is stopped at the position Ps1 and rotates the drive motor 42 in the reverse direction, that is, in the clockwise direction. To the right in FIG. When the output of the first position sensor 81 changes from on to off, the controller 87 starts the pulse count of the encoder 69, and when the number of output pulses reaches a preset number of braking pulses Nbr12, the control unit 87 Connect and apply a short brake to the drive motor 42.

  Thereafter, when the drive motor 42 rotates by inertia, the rack member 43 further moves to enter the first home position Hp1, and the first position sensor 81 detects the edge 75b of the first flag 75 and changes from OFF to ON. The control unit 87 starts the pulse count of the encoder 69. When the number of output pulses of the encoder reaches a preset sheet conveyance pulse number ΔNid12, the control unit 87 operates the pair of conveyance rollers 31 to convey the sheet punched in the backward stroke from the punching processing position. .

  Due to the inertial rotation of the drive motor 42, the rack member 43 further moves within the first home position Hp1, and stops at or near the reference position PR. When the forward stroke of the four-hole punching operation is subsequently performed, the control unit 87 operates the pair of conveying rollers 31 to carry in the next sheet, and positions and holds the next sheet at the punching processing position. By repeating the reciprocating process in this manner, four punch holes can be efficiently and reliably formed in a plurality of sheets continuously introduced from the image forming apparatus A with high quality.

  In the 2-hole drilling operation, the same reciprocating process as that in the 4-hole drilling operation is performed. In the forward stroke of the two-hole drilling operation, the control unit 87 activates the drive motor 42 and rotates it clockwise to move the rack member 43 to the right side in FIG. 2 along the longitudinal direction. When the output of the first position sensor 81 changes from on to off, the control unit 87 starts the pulse count of the encoder 69, and when the number of output pulses reaches a preset number of braking pulses Nbr21, the control unit 87 Connect and apply a short brake to the drive motor 42.

  Thereafter, when the drive motor 42 rotates by inertia, the rack member 43 enters the second home position Hp2, and the first position sensor 81 detects the edge 76a of the second flag 76 and changes from OFF to ON, the control unit 87. Starts the pulse count of the encoder 69. When the number of output pulses of the encoder reaches a preset sheet conveyance pulse number ΔNid21, the control unit 87 operates the pair of conveyance rollers 31 to convey the punched sheet from the punching processing position.

  The rack member 43 further moves due to inertial rotation of the drive motor 42 and stops at a position Ps2 within the second home position Hp2. When the backward stroke of the two-hole punching operation is performed after the conveyance of the sheet, the control unit 87 operates the pair of conveyance rollers 31 to carry in the next sheet, and positions and holds the next sheet at the punching processing position.

  In the backward stroke of the two-hole drilling operation, the control unit 87 starts the drive motor 42 from the state where the rack member 43 is stopped at the position Ps2 and rotates it in the reverse direction, that is, counterclockwise, thereby causing the rack member 43 to move in the longitudinal direction. Move in the opposite direction. When the output of the first position sensor 81 changes from on to off, the control unit 87 starts the pulse count of the encoder 69. When the number of output pulses reaches a preset number of braking pulses Nbr22, the control unit 87 Connect and apply a short brake to the drive motor 42.

  Thereafter, when the drive motor 42 rotates by inertia, the rack member 43 further moves and enters the first home position Hp1, and the first position sensor 81 detects the edge 75a of the first flag 75 and changes from OFF to ON. The control unit 87 starts the pulse count of the encoder 69. When the output pulse number of the encoder reaches a preset sheet conveyance pulse number ΔNid22, the control unit 87 operates the pair of conveyance rollers 31 to convey the sheet punched in the backward stroke from the punching processing position. .

  Due to the inertial rotation of the drive motor 42, the rack member 43 further moves within the first home position Hp1, and stops at or near the reference position PR. When the forward stroke of the 2-hole punching operation is subsequently performed, the control unit 87 operates the pair of conveying rollers 31 to carry in the next sheet, and positions and holds the next sheet at the punching processing position. By repeating the reciprocating process in this way, two punch holes can be efficiently and reliably formed on a plurality of sheets continuously introduced from the image forming apparatus A with high quality.

  As mentioned above, although this invention was demonstrated in relation to preferred embodiment, this invention is not limited to the said embodiment, In the technical scope, it can implement by adding various change or deformation | transformation. Needless to say. For example, the present invention also relates to a sheet processing apparatus including a punching device having a driving force transmission mechanism other than the above-described configuration including a rack member, a gear mechanism, and a cam mechanism in order to transmit rotation of a driving motor to a plurality of punch members. Can be applied as well. In addition, the number, arrangement, and interval of the punch members provided in the punching device can be variously changed.

A Image forming apparatus B Sheet post-processing apparatus C Punching device 40, 40a to 40d Punch member 42 Drive motor 43 Rack member 44 Upper frame 45 Lower frame 53 Punching blade 56 Cam member 57 Driven gear 60, 60a to 60d Cam groove 61 Cam pin 62 Linear part 63 Inclined part 69 Encoder 73 Rack position detection mechanism 75-78 Flag 81-83 Position sensor

Claims (10)

A sheet conveying unit that conveys the punched sheet from a predetermined processing position;
A plurality of punch members that reciprocate between a standby position and a punching position to punch the sheet at the predetermined processing position;
A common drive motor for reciprocating the plurality of punch members between the standby position and the punching position;
A control unit for controlling the sheet conveying unit,
The controller determines that all of the plurality of punch members are in the standby position, and conveys the punched sheet from the predetermined processing position when the drive motor rotates a predetermined amount of rotation based on the determination. A sheet processing apparatus that controls the sheet conveying unit.   The sheet processing apparatus according to claim 1, further comprising an encoder that detects a rotation amount of the drive motor, wherein the control unit detects the predetermined rotation amount based on the number of output pulses of the encoder.   The control unit further includes a common driving force transmission member that moves the plurality of punch members to reciprocate between the standby position and the punching position by rotation of the drive motor, and the control unit includes the plurality of punch members. The sheet processing apparatus according to claim 1, wherein it is determined from the position of the driving force transmission member that all the members are in the standby position.   A detector that moves integrally with the driving force transmission member; and a sensor that detects and outputs the detector, and the control unit is configured to detect all of the plurality of punch members based on the output of the sensor. The sheet processing apparatus according to claim 3, wherein the sheet processing apparatus determines that the apparatus is in the standby position.   In the forward stroke in which the driving force transmission member linearly moves in either direction and the reverse stroke in which the driving force transmission member moves in the opposite direction after the forward stroke, the punch member is between the standby position and the punching position, respectively. So that the control unit can determine that all of the plurality of punch members are in the standby position after punching the sheet in the forward stroke and the backward stroke, respectively. The sheet processing apparatus according to claim 4, wherein a plurality of detectors are provided. A sheet conveying section that conveys the punched sheet from a predetermined processing position; a plurality of punch members that reciprocate between a standby position and a punching position to punch a sheet at the predetermined processing position; A sheet processing method using a common drive motor that reciprocates the punch member between the standby position and the punching position,
It is determined that all of the plurality of punch members are at the standby position, and when the driving motor rotates a predetermined amount of rotation based on the determination, the punched sheet is conveyed from the predetermined processing position. A sheet processing method for controlling a sheet conveying unit.   The sheet processing method according to claim 6, wherein an amount of rotation of the drive motor is detected using an encoder, and the predetermined amount of rotation is detected based on the number of output pulses of the encoder.   The plurality of punch members are reciprocated between the standby position and the punching position using a common driving force transmission member that moves by rotation of the drive motor, and all of the plurality of punch members are in the standby position. The sheet processing method according to claim 6, wherein the determination is made from the position of the driving force transmission member.   9. The brake is applied to the drive motor before all of the plurality of punch members enter the standby position so as to stop after rotating beyond the predetermined rotation amount. 10. Sheet processing method.   An image forming apparatus comprising the sheet processing apparatus according to claim 1.

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