Sheet processing apparatus and image forming system

Abstract

To provide a sheet processing device and an image forming system having the sheet processing device with improved accuracy of punching a sheet.SOLUTION: A sheet processing device includes: a first conveying rotator that conveys a sheet in a sheet conveying direction; a second conveying rotator that conveys a sheet; a punch member that punches the sheet conveyed by the first conveying rotator while rotating; a sensor that is provided between the first conveying rotator and the punch member in the sheet conveying direction, and that changes an output value based on presence or absence of a sheet at a detection position; a punch motor driven based on a detection result of the sensor to drive the punch member; a conveying motor that drives the first conveying rotator and the second conveying rotator; a pinion gear fixed to an output shaft of the conveying motor; an output gear fixed to a drive shaft of the first conveying rotator; and an idler gear meshing with the pinion gear and the output gear.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sheet processing apparatus for processing sheets and an image forming system including the same. [Background technology]

[0002] Conventionally, there has been proposed a finisher that is connected to an image forming apparatus such as a printer and performs a punching process on a sheet discharged from the image forming apparatus (see Patent Document 1). This finisher has a sheet detection sensor that detects the sheet, a pair of conveying rollers that convey the sheet, and a punching means that punches holes in the sheet conveyed by the pair of conveying rollers. The punching means has a punch and a die each journaled on a casing, and a punch drive motor that drives the punch and the die in synchronization.

[0003] The punch and die are stopped and wait at a home position, and are driven by a punch drive motor when the sheet detection sensor detects the rear end of the sheet. The punch and die then mesh with each other at a predetermined position of the rear end of the sheet, and punch a hole in the sheet being conveyed by the conveying roller pair. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-279170 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the finisher described in Patent Document 1, when the leading edge of the sheet is pinched between the pair of conveying rollers, the rotation speed of the conveying rollers fluctuates, and there is a risk that the sheet detection sensor detects the conveyed sheet in a state where the sheet conveying speed is unstable. As a result, the timing at which the punch and die start driving is shifted from the desired timing, and there is a risk of the punching accuracy being reduced.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a sheet processing apparatus with improved accuracy in punching holes in sheets, and an image forming system including the same. [Means for solving the problem]

[0007] a punch member disposed between the first conveying rotor and the second conveying rotor in the sheet conveying direction and punching a hole in the sheet conveyed by the first conveying rotor while rotating; a sensor disposed between the first conveying rotor and the punch member in the sheet conveying direction and changing an output value based on the presence or absence of a sheet at a detection position; a punch motor that is driven based on a detection result of the sensor and drives the punch member; a conveying motor that drives the first conveying rotor and the second conveying rotor; a first drive transmission section having a first number of drive transmission members that sequentially transmit a drive force of the conveying motor to the first conveying rotor; and a second drive transmission section having a second number, which is greater than the first number, of drive transmission members that sequentially transmit a drive force of the conveying motor to the second conveying rotor. the first conveying rotor and the second conveying rotor convey the sheet, which is conveyed at a first speed upstream of the first conveying rotor in the sheet conveying direction, at a second speed faster than the first speed, and the first conveying rotor rotates at a rated speed so as to be able to convey the sheet at the second speed after the leading edge of the sheet has passed the first conveying rotor and before it reaches the detection position of the sensor. It is characterized by:

[0008] The present invention also provides a sheet processing apparatus comprising: a first conveying rotor that conveys a sheet in a sheet conveying direction; a second conveying rotor that is disposed downstream of the first conveying rotor in the sheet conveying direction and conveys a sheet; a punch member that is disposed between the first conveying rotor and the second conveying rotor in the sheet conveying direction and perforates a hole in the sheet conveyed by the first conveying rotor while rotating; a sensor that is disposed between the first conveying rotor and the punch member in the sheet conveying direction and changes an output value based on the presence or absence of a sheet at a detection position; a punch motor that is driven based on a detection result of the sensor and drives the punch member; a conveying motor that drives the first conveying rotor and the second conveying rotor; a pinion gear fixed to an output shaft of the conveying motor; an output gear fixed to a drive shaft of the first conveying rotor; and an idler gear that meshes with the pinion gear and the output gear. the first conveying rotor and the second conveying rotor convey the sheet, which is conveyed at a first speed upstream of the first conveying rotor in the sheet conveying direction, at a second speed faster than the first speed, and the first conveying rotor rotates at a rated speed so as to be able to convey the sheet at the second speed after the leading edge of the sheet has passed the first conveying rotor and before it reaches the detection position of the sensor. It is characterized by:

[0009] The present invention also provides a sheet processing apparatus comprising: a first conveying rotor that conveys a sheet in a sheet conveying direction; a second conveying rotor that is disposed downstream of the first conveying rotor in the sheet conveying direction and conveys a sheet; a punch member that is disposed between the first conveying rotor and the second conveying rotor in the sheet conveying direction and perforates a hole in the sheet conveyed by the first conveying rotor while rotating; a sensor that is disposed between the first conveying rotor and the punch member in the sheet conveying direction and changes an output value based on the presence or absence of a sheet at a detection position; a punch motor that is driven based on a detection result of the sensor and drives the punch member; a conveying motor that drives the first conveying rotor and the second conveying rotor; an output gear fixed to a drive shaft of the first conveying rotor; and a gear fixed to an output shaft of the conveying motor and meshing with the output gear. the first conveying rotor and the second conveying rotor convey the sheet, which is conveyed at a first speed upstream of the first conveying rotor in the sheet conveying direction, at a second speed faster than the first speed, and the first conveying rotor rotates at a rated speed so as to be able to convey the sheet at the second speed after the leading edge of the sheet has passed the first conveying rotor and before it reaches the detection position of the sensor. It is characterized by: Effect of the Invention

[0010] According to the present invention, drilling accuracy can be improved. [Brief description of the drawings]

[0011] [Figure 1] 1 is an overall schematic diagram showing an image forming system according to a first embodiment. [Diagram 2] 1A is a diagram showing the punch and die positioned at the start of punching position, FIG. 1B is a diagram showing the punch and die positioned at the meshing position, and FIG. 1C is a diagram showing the punch and die positioned at the end of punching position. [Diagram 3] FIG. 4 is a diagram showing a drive transmission configuration of a punching device and a horizontal conveying unit. [Figure 4] 6 is a graph showing speed fluctuations of an inlet roller during a series of punching operations of the punch unit. [Diagram 5] 1A is a diagram showing the state when the sheet enters the inlet rollers, FIG. 1B is a diagram showing the state immediately before the inlet sensor detects the passage of the leading edge of the sheet, and FIG. 1C is a diagram showing the state when punching of the sheet is completed. [Figure 6] FIG. 11 is a perspective view showing a scissors gear according to a second embodiment. [Figure 7] FIG. 7 is an enlarged view showing the dashed line portion in FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <First embodiment> [Overall structure] As shown in Fig. 1, an image forming system 1S according to the first embodiment is composed of an image forming apparatus 1, an image reading apparatus 2, a document feeder 3, and a sheet processing apparatus 4. The image forming system 1S forms an image on a sheet, which is a recording material, and outputs the sheet by processing it using the sheet processing apparatus 4 as necessary. Below, the operation of each apparatus will be briefly described, and then the sheet processing apparatus 4 will be described in detail. Note that below, a roller pair having a drive roller and a driven roller connected to the drive roller may also be simply referred to as a roller.

[0013] The document feeder 3 transports the document placed on the document tray 18 to the image reading units 16 and 19. The image reading units 16 and 19 are each an image sensor that reads image information from the document surface, and both sides of the document are read in one document transport. The document from which the image information has been read is discharged to the document discharge unit 20. In addition, the image reading unit 2 can read image information from a stationary document set on the document glass (including a document that cannot be used by the document feeder 3, such as a booklet document) by reciprocating the image reading unit 16 using the drive unit 17.

[0014] The image forming apparatus 1 is an electrophotographic apparatus equipped with a direct transfer type image forming section 1B. The image forming section 1B is equipped with a cartridge 8 equipped with a photosensitive drum 9, and a laser scanner unit 15 arranged above the cartridge 8. When performing an image forming operation, the surface of the rotating photosensitive drum 9 is charged, and the laser scanner unit 15 exposes the photosensitive drum 9 based on image information to write an electrostatic latent image on the drum surface. The electrostatic latent image carried on the photosensitive drum 9 is developed into a toner image by charged toner particles, and the toner image is conveyed to a transfer section where the photosensitive drum 9 and a transfer roller 10 face each other. A controller of the image forming apparatus 1 performs an image forming operation by the image forming section 1B based on image information read by the image reading sections 16 and 19 or image information received from an external computer via a network.

[0015] The image forming apparatus 1 includes a plurality of feeding devices 6 which feed sheets as recording materials one by one at a predetermined interval. The sheets fed from the feeding devices 6 are conveyed to a transfer section after skew correction by registration rollers 7, where the toner image carried on a photosensitive drum 9 is transferred onto the sheets. A fixing unit 11 is disposed downstream of the transfer section in the sheet conveying direction. The fixing unit 11 has a pair of rotating bodies which sandwich and convey the sheets, and a heating element such as a halogen lamp for heating the toner image, and fixes the image by applying heat and pressure to the toner image on the sheet.

[0016] When the sheet on which an image has been formed is discharged outside the image forming apparatus 1, the sheet that has passed the fixing unit 11 is conveyed to the sheet processing device 4 by conveying rollers 81, 82 arranged in the horizontal conveying section 14. In the case of a sheet on which image formation on the first side has been completed in double-sided printing, the sheet that has passed the fixing unit 11 is handed over to the reversing rollers 12, is switched back and conveyed by the reversing rollers 12, and is conveyed again to the registration rollers 7 via the re-conveying section 13. Then, the sheet passes again through the transfer section and the fixing unit 11 to form an image on the second side, and is then conveyed to the sheet processing device 4 by the conveying rollers 81, 82 arranged in the horizontal conveying section 14.

[0017] The image forming unit 1B is an example of an image forming unit that forms an image on a sheet, and may be an electrophotographic unit of an intermediate transfer type that transfers a toner image formed on a photoreceptor to a sheet via an intermediate transfer body. Also, a printing unit of an inkjet type or an offset printing type may be used as the image forming unit.

[0018] [Sheet processing device] The sheet processing device 4 has a punching device 100 that punches holes in sheets, and punches the sheets received from the image forming device 1 and discharges them as a sheet stack. The sheet processing device 4 can also simply discharge the sheets received from the image forming device 1 without punching them.

[0019] The sheet processing device 4 is provided with an incoming path 61, an inner discharge path 62, a first discharge path 63, and a second discharge path 64 as transport paths for transporting sheets, and an upper discharge tray 25 and a lower discharge tray 37 as destinations for discharging sheets. The incoming path 61 as the first transport path is a transport path that receives and guides sheets from the image forming device 1, and the inner discharge path 62 as the second transport path is a transport path that extends below the incoming path 61 and guides the sheets toward the alignment unit 4A. The first discharge path 63 is a transport path that discharges the sheets to the upper discharge tray 25, and the second discharge path 64 as the third transport path is a transport path that extends from the intermediate stacking unit 40 toward the bundle discharge rollers 36 and guides the sheets to the bundle discharge rollers 36.

[0020] The sheet discharged from the horizontal conveying section 14 of the image forming apparatus 1 is received by the punching device 100 arranged in the receiving path 61 and subjected to a punching process. The punching device 100 has an inlet roller 71 as a first conveying rotator, an outlet roller 72 as a second conveying rotator, an inlet sensor 73 as a sensor, and a punch unit 74. The sheet discharged from the image forming apparatus 1 is conveyed by the inlet roller 71 and subjected to a punching process by the punch unit 74. The sheet subjected to the punching process is conveyed toward the pre-reversal roller 22 by the outlet roller 72 arranged downstream of the inlet roller 71 in the sheet conveying direction. The inlet sensor 73 changes an output value (for example, a voltage value or an output signal) based on the presence or absence of a sheet at a detection position between the inlet roller 71 and the punch unit 74 in the sheet conveying direction. The pre-reversal roller 22 conveys the sheet received from the punching device 100 toward the first discharge path 63.

[0021] The sheet conveying speed V2 (see FIG. 5(b), second speed) by the inlet roller 71 is set to be higher than the sheet conveying speed V1 (see FIG. 5(a), first speed) by the conveying rollers 81, 82 arranged in the horizontal conveying section 14. The conveying roller 82 as a third conveying rotor passes the sheet to the inlet roller 71. Therefore, when the inlet roller 71 receives the sheet, the sheet accelerates. One-way clutches 91, 92, which will be described later, are provided in the drive transmission path between the conveying rollers 81, 82 of the horizontal conveying section 14 and a conveying motor M3 (see FIG. 3), which drives the conveying rollers. Even if the sheet is pulled by the conveying rollers 81, 82 and the inlet roller 71, the one-way clutches 91, 92 allow the sheet to rotate freely.

[0022] When the sheet is discharged to the upper discharge tray 25, the reversing roller 24 discharges the sheet received from the pre-reversing roller 22 to the upper discharge tray 25. When the sheet is discharged to the lower discharge tray 37, the reversing roller 24 as a reversing unit performs switchback transport to reverse the sheet received from the pre-reversing roller 22, and transports the sheet to the inner discharge path 62. A guide member 23 and a branching sensor 41 are arranged at a branching portion where the receiving path 61 and the inner discharge path 62 branch off from the first discharge path 63, upstream of the reversing roller 24 in the sheet discharge direction by the reversing roller 24. The guide member 23 has a function of restricting the sheet switched back by the reversing roller 24 from flowing back into the receiving path 61. The branching sensor 41 is provided at a branching portion between the receiving path 61 and the first discharge path 63, and detects that the rear end of the sheet has passed the detection position of the branching sensor 41. The reversing roller 24 switches the rotation direction from the forward direction to the reverse direction based on the detection result of the branching sensor 41.

[0023] The inner discharge roller 26, the intermediate conveying roller 28, and the kick-out roller 29, which are a pair of rotating bodies arranged in the inner discharge path 62, convey the sheet received from the reversing roller 24 toward the alignment unit 4A while transferring the sheet in order. The intermediate pre-stacking sensor 38 detects the sheet between the intermediate conveying roller 28 and the kick-out roller 29. As the entrance sensor 73, the branching section sensor 41, and the intermediate pre-stacking sensor 38, for example, an optical sensor that detects the presence or absence of a sheet at the detection position using light, or a flag sensor that uses a flag pressed against the sheet, is used.

[0024] The alignment section 4A has a bundle holding flag 30, an intermediate stacking section 40 as a stacking section, a vertical alignment plate 39, a half-moon roller 33, a bundle discharge guide 34, and a drive belt 35. The intermediate stacking section 40 is composed of an intermediate upper guide 31 and an intermediate lower guide 32, and multiple sheets are stacked as a sheet bundle.

[0025] The sheet stack discharged toward the intermediate stacking section 40 by the kick-out roller 29, which is a roller pair, is pressed against the intermediate lower guide 32 by the stack holding flag 30. This prevents the sheets stacked in the intermediate stacking section 40 from lifting up so that the trailing end of the sheet stacked in the intermediate stacking section 40 does not interfere with the leading end of the following sheet. The half-moon roller 33 rotates based on the detection of a sheet by the intermediate stacking pre-sensor 38, and transports the sheet toward the vertical alignment plate 39 of the intermediate stacking section 40. The transport pressure of the half-moon roller 33 is adjusted to slip the surface of the sheet that hits the vertical alignment plate 39.

[0026] The sheet bundle discharged to the intermediate stacking section 40 is guided downward along the intermediate lower guide 32 and aligned by a vertical alignment plate 39 provided at the downstream end of the intermediate stacking section 40 in the sheet conveying direction. The sheet bundle aligned in the sheet conveying direction by the vertical alignment plate 39 is aligned in the width direction perpendicular to the sheet conveying direction by a horizontal alignment plate (not shown). After such alignment processing is performed, the sheet bundle is pushed out by a bundle discharge guide 34 fixed to the drive belt 35 and delivered to the bundle discharge rollers 36 via a second discharge path 64. The sheet bundle is discharged outside the machine by the bundle discharge rollers 36 as a discharge section and stacked on the lower discharge tray 37. The sheet bundle aligned in the intermediate stacking section 40 may be bound by a stapler (not shown).

[0027] Both the upper discharge tray 25 and the lower discharge tray 37 are movable up and down relative to the housing of the sheet processing device 4. The sheet processing device 4 is equipped with sheet surface detection sensors that detect the top surface position of the sheets (stacking height of the sheets) on the upper discharge tray 25 and the lower discharge tray 37, and when either sensor detects a sheet, the corresponding tray is lowered in the A2, B2 direction. Also, when the sheet surface detection sensor detects that a sheet has been removed from the upper discharge tray 25 or the lower discharge tray 37, that tray is raised in the A1, B1 direction. Therefore, the upper discharge tray 25 and the lower discharge tray 37 are controlled to rise and fall so as to keep the top surfaces of the stacked sheets constant.

[0028] [Drilling device] Next, the punching device 100 will be described with reference to Figures 2(a) to (c). Figure 2(a) is a diagram showing the punch 202 and die 205 positioned at a punching start position where punching into the sheet SH begins. Figure 2(b) is a diagram showing the punch 202 and die 205 positioned at a meshing position. Figure 2(c) is a schematic diagram showing the punch 202 and die 205 positioned at a punching end position.

[0029] As described above, the punching device 100 has the inlet rollers 71, the outlet rollers 72, the inlet sensor 73, and the punch unit 74. The punch unit 74 is a rotary type punching unit that punches holes in a sheet with a rotating punch.

[0030] As shown in FIG. 2(a), the punch unit 74 includes a punch 202 supported rotatably around a punch shaft 201, a die 205 rotating around a die shaft 204, and a punch HP sensor S1. The die 205 has a die hole 205a that can mesh with the punch 202, and the punch shaft 201 and the die shaft 204 mesh with a gear (not shown) driven by a punch drive motor M1 serving as a punch motor. In FIG. 2(a), the punch 202 serving as a punch member is driven to rotate in a clockwise direction by being driven by the punch drive motor M1, and the die 205 is driven to rotate in a counterclockwise direction. The punch 202 and the die 205 are disposed between the entrance roller 71 and the exit roller 72 in the sheet conveying direction.

[0031] In addition, the punch HP sensor S1 detects the rotational position of the punch 202, for example, by detecting a flag that rotates in conjunction with the die shaft 204. In this embodiment, a transmission type photosensor is used for the punch HP sensor S1, and a stepping motor is used for the punch drive motor M1.

[0032] The punch 202 and the die 205 are located at their home positions at the start and end of an image forming job for forming an image on a sheet SH, and are stopped at the home positions even when no job is input. The punch 202 and the die 205 are arranged so as not to interfere with the conveyance of the sheet at the home positions. The home position of the punch 202 is a position rotated a predetermined angle upstream in the rotation direction from the meshing position where the punch 202 and the die 205 mesh. The home position of the punch 202 is detected by a punch HP sensor S1.

[0033] 2(a) to 2(c), the sheet SH is conveyed at a constant speed by entrance rollers 71 and exit rollers 72 driven by a conveying motor M2, and the punch 202 and the die 205 rotate in synchronization with the sheet SH. When the punch 202 and the die 205 are positioned at the meshing position, the punch 202 meshes with the die hole 205a of the die 205, and the sheet SH is perforated.

[0034] In this way, the punch 202 and the die 205 wait at the home position, and are driven by the punch drive motor M1 at a predetermined timing based on the entrance sensor 73 detecting the leading edge of the sheet. At this time, the punch drive motor M1 is controlled so that the peripheral speed of the punch 202 and the die 205 and the conveying speed of the sheet SH match, preventing the sheet from becoming wrinkled or torn during punching. The punch 202 and the die 205 move away from the punched sheet at the punching end position.

[0035] [Drive transmission configuration] Next, the drive transmission configuration of the punching device 100 and the horizontal conveying section 14 will be described. First, the drive transmission configuration of the punching device 100 will be described. As shown in Fig. 3, a pinion gear M2P is fixed to the output shaft of the conveying motor M2 of the punching device 100, and a large diameter gear 75a of an idler gear 75 meshes with the pinion gear M2P. The idler gear 75 is a gear in which a large diameter gear 75a and a small diameter gear 75b are integrated together.

[0036] The small diameter gear 75b of the idler gear 75 meshes with the inlet roller gear 76, and the inlet roller gear 76, which serves as an output gear, is fixed to the drive shaft 71a of the inlet roller 71. In this way, the conveying motor M2 drives the inlet roller 71 via the pinion gear M2P, the idler gear 75, and the inlet roller gear 76. In other words, the pinion gear M2P, the idler gear 75, and the inlet roller gear 76 constitute a first drive transmission unit DT1 that has only three drive transmission members as a first number that sequentially transmit the driving force of the conveying motor M2 to the inlet roller 71.

[0037] Further, the large diameter gear 75a of the idler gear 75 is meshed with the gear 77a of the pulley gear 77. The pulley gear 77 is formed by integrating the gear 77a and the pulley 77b. A belt 78 is wound around the pulley 77b of the pulley gear 77 and a pulley 79 fixed to the drive shaft 72a of the exit roller 72, and the belt 78 transmits the rotation of the pulley 77b to the pulley 79. In this manner, the conveying motor M2 drives the exit roller 72 via the pinion gear M2P, the idler gear 75, the pulley gear 77, the belt 78, and the pulley 79. In other words, the pinion gear M2P, the idler gear 75, the pulley gear 77, the belt 78, and the pulley 79 constitute a second drive transmission unit DT2 having only five drive transmission members as a second number that sequentially transmit the drive force of the conveying motor M2 to the exit roller 72. The number of drive transmission members of the second drive transmission part DT2 (five) is greater than the number of drive transmission members of the first drive transmission part DT1 (three).

[0038] In this embodiment, the pulley gear 77 and the pulley 79 are connected by the belt 78, but instead of the pulley 79 and the belt 78, gears may be used, respectively.

[0039] Next, a description will be given of the drive transmission configuration of the horizontal conveying unit 14. A pinion gear M3P is fixed to the output shaft of the conveying motor M3, and the pinion gear M3P meshes with a large diameter gear 84a of an idler gear 84. The idler gear 84 is a gear in which a large diameter gear 84a and a small diameter gear 84b are integrated together.

[0040] A gear 85a of the conveying pulley gear 85 meshes with the small diameter gear 84b of the idler gear 84. The conveying pulley gear 85 is a combination of a gear 85a and a pulley 85b. The conveying pulley gear 85 is fixed to a drive shaft 81a of the conveying roller 81. A belt 83 is wound around the pulley 85b of the conveying pulley gear 85 and a pulley 86 fixed to the drive shaft 82a of the conveying roller 82, and the belt 83 transmits the rotation of the pulley 85b to the pulley 86. In this way, the conveying motor M3 drives the conveying rollers 81 and 82 via the pinion gear M3P, the idler gear 84, the conveying pulley gear 85, the belt 83, and the pulley 86.

[0041] The conveying pulley gear 85 and the pulley 86 each have a built-in one-way clutch 91, 92, so that the conveying rollers 81, 82 are configured to be rotatable in response to the rotation of the sheet SH.

[0042] [Speed ​​fluctuation of inlet roller] Next, the speed fluctuation of the inlet roller 71 of the punching device 100 will be described. Fig. 4 shows the speed fluctuation of the inlet roller 71 in a series of punching operations of the punch unit 74. Fig. 5(a) is a diagram showing a state when the sheet SH enters the inlet roller 71. Fig. 5(b) is a diagram showing a state immediately before the inlet sensor 73 detects the passage of the leading edge of the sheet SH. Fig. 5(c) is a diagram showing a state when punching of the sheet SH is completed.

[0043] 5(a), when the leading edge of the sheet SH enters the nip of the inlet rollers 71, the sheet SH is sandwiched between the inlet rollers 71 and the conveying rollers 82. Since the sheet conveying speed V2 by the inlet rollers 71 is faster than the sheet conveying speed V1 by the conveying rollers 82, the sheet SH is pulled downstream in the sheet conveying direction D1, and the load on the conveying motor M2 becomes heavy. Note that the conveying force of the inlet rollers 71 is set to be larger than the conveying resistance of the conveying rollers 82.

[0044] Then, the speed of the inlet rollers 71, which had been rotating at a predetermined rated speed, slows down as shown at time A in Fig. 4. The conveying motor M2 increases the rotation speed to rotate the inlet rollers 71 at a constant speed, and the speed of the inlet rollers 71 increases as shown at time B in Fig. 4.

[0045] As shown in Fig. 5(b), after the leading edge of the sheet SH passes through the inlet rollers 71, the speed of the inlet rollers 71 converges to a predetermined rated speed as shown at time C in Fig. 4. Thereafter, the leading edge of the sheet SH passes through the detection position of the inlet sensor 73, and the punch 202 and the die 205 of the punch unit 74 rotate based on the detection result of the inlet sensor 73. In other words, time C at which the speed of the inlet rollers 71 converges to the predetermined rated speed is the timing before the leading edge of the sheet SH passes through the detection position of the inlet sensor 73.

[0046] Even when punching of the sheet SH is completed as shown in Fig. 5(c), the speed of the inlet rollers 71 is maintained at the rated speed as shown at time point D in Fig. 4. That is, as shown in Fig. 5(b), the speed of the inlet rollers 71 stabilizes at the rated speed before the leading edge of the sheet SH passes the detection position of the inlet sensor 73, so that the timing at which the punch unit 74 starts to drive is stabilized. This makes it possible to reduce deviations in the timing at which the punch 202 punches holes in the sheet SH, and improves the accuracy of punching holes in the sheet SH.

[0047] Here, we will explain the speed fluctuation of the inlet roller 71 in a comparative example when another drive transmission member such as a belt is added to the drive train between the conveying motor M2 and the inlet roller 71. The dashed line in Fig. 4 shows the speed fluctuation of the inlet roller 71 in this comparative example. When a belt is added to the drive train between the conveying motor M2 and the inlet roller 71, a drive transmission loss occurs due to the bending of the belt.

[0048] When the leading edge of the sheet SH enters the nip of the inlet rollers 71, the speed of the inlet rollers 71 decreases significantly as shown at time E in Fig. 4. The conveying motor M2 increases the rotation speed to rotate the inlet rollers 71 at a constant speed, and the speed of the inlet rollers 71 increases significantly as shown at time F in Fig. 4. Thus, in the comparative example, the speed fluctuation of the inlet rollers 71 is larger than in this embodiment.

[0049] For this reason, it takes longer for the speed of the inlet rollers 71 to stabilize at the rated speed than in this embodiment, and even at time C when the leading edge of the sheet SH passes the detection position of the inlet sensor 73, the speed of the inlet rollers 71 has not converged to the rated speed. For this reason, the time from when the leading edge of the sheet SH is detected by the inlet sensor 73 to when the sheet SH is punched by the punch 202 is not stable, and the punching timing is shifted. Therefore, in the comparative example, a hole cannot be punched at the desired position, and the accuracy of punching into the sheet is reduced.

[0050] As described above, in this embodiment, the drive transmission configuration from the conveying motor M2 to the inlet roller 71 is made up of the pinion gear M2P, the idler gear 75, and the inlet roller gear 76, and the number of gears as drive transmission members is small. Furthermore, gears have less drive transmission loss such as slippage compared to belts and the like, and can transmit the drive force directly. Therefore, it is possible to suppress the speed fluctuation of the inlet roller 71 when the leading edge of the sheet SH enters the inlet roller 71.

[0051] Therefore, the inlet rollers 71 as the first conveying rotator rotate at a rated speed so that the sheet SH can be conveyed at the conveying speed V2 after the leading edge of the sheet SH has passed the inlet rollers 71 and before it reaches the detection position of the inlet sensor 73. This can reduce the deviation in timing at which the punch 202 punches holes in the sheet SH, thereby improving the punching accuracy of the sheet SH.

[0052] In this embodiment, the rotation of the conveying motor M2 is transmitted to the inlet roller 71 via the pinion gear M2P, the idler gear 75, and the inlet roller gear 76, but this is not limited to the above. For example, the idler gear 75 may be omitted, and the pinion gear M2P as a gear may mesh with the inlet roller gear 76. Also, multiple idler gears may be provided between the pinion gear M2P and the inlet roller gear 76. However, the fewer the number of idler gears between the pinion gear M2P and the inlet roller gear 76, the more directly the driving force can be transmitted.

[0053] <Second embodiment> Next, a second embodiment of the present invention will be described. In the second embodiment, the idler gear 75 of the first embodiment is replaced with a scissors gear 200. Therefore, the same configuration as the first embodiment will be described by omitting illustrations or by assigning the same reference numerals in the drawings.

[0054] As shown in Fig. 6, the pinion gear M2P of the conveying motor M2 (see Fig. 3) meshes with the scissors gear 200. The scissors gear 200 meshes with the inlet roller gear 76 and the pulley gear 77 (see Fig. 3). The scissors gear 200 has two gears 211, 212 arranged on the same axis, and the gears 211, 212 as the first gear and the second gear are fixed by a fixing part 214 in a state where they are out of phase with each other.

[0055] Fig. 7 is an enlarged view showing a dashed line portion 213 in Fig. 6. As shown in Fig. 7, gears 211 and 212 of scissors gear 200 are shifted in phase with each other so as to sandwich tooth M2X of pinion gear M2P. Then, on one side of tooth M2X, there is no gap (backlash) between tooth M2X and gear 211, and on the other side of tooth M2X, there is no gap (backlash) between tooth M2X and gear 212. This enables scissors gear 200 to eliminate backlash with respect to pinion gear M2P.

[0056] As described above, in this embodiment, by using the scissors gear 200 in the drive transmission configuration between the conveying motor M2 and the inlet rollers 71, it is possible to eliminate backlash between the pinion gear M2P and the scissors gear 200. This allows the drive force of the conveying motor M2 to be directly transmitted to the inlet rollers 71, and it is possible to reduce the speed fluctuation of the inlet rollers 71 when the sheet SH enters the inlet rollers 71. This improves the accuracy of punching holes in the sheet SH.

[0057] <Other embodiments> In any of the above-described embodiments, the one-way clutches 91, 92 are provided so that the conveying rollers 81, 82 can rotate following the sheet SH conveyed at the conveying speed V2 by the inlet roller 71. However, the present invention is not limited to this. For example, instead of providing the one-way clutches 91, 92, the conveying rollers 81, 82 may be configured to be movable so that the nip between the conveying rollers 81, 82 can be released.

[0058] In addition, in each of the above-described embodiments, the electrophotographic image forming apparatus 1 has been used for explanation, but the present invention is not limited to this. For example, the present invention can also be applied to a sheet processing apparatus connected to an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from a nozzle.

[0059] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0060] 1: Image forming apparatus / 1S: Image forming system / 4: Sheet processing device / 24: Reversing section (reversing roller) / 26: Rotating body pair (inner discharge roller) / 36: Discharge section (bundle discharge roller) / 40: Loading section (intermediate stacking section) / 61: First conveying path (receiving path) / 62: Second conveying path (inner discharge path) / 64: Third conveying path (second discharge path) / 71: First conveying rotating body (entrance roller) / 71a: Drive shaft / 72: Second conveying rotating body (exit roller) / 73: Sensor (entrance sensor) / 75: Idler gear / 76: Output gear (entrance : 3rd conveying rotor (conveying roller) / 92: one-way clutch / 200: scissors gear / 202: punch member (punch) / 211, 212: 1st gear, 2nd gear (gear) / D1: sheet conveying direction / DT1: 1st drive transmission section / DT2: 2nd drive transmission section / M1: punch motor (punch drive motor) / M2: conveying motor / M2P: pinion gear, gear / M3: motor (conveying motor) / SH: sheet / V1: 1st speed (conveying speed) / V2: 2nd speed (conveying speed)

Claims

1. a first conveying rotating body that conveys the sheet in a sheet conveying direction; a second conveying rotor disposed downstream of the first conveying rotor in the sheet conveying direction and configured to convey a sheet; a punch member disposed between the first conveying rotor and the second conveying rotor in the sheet conveying direction, the punch member rotating to punch holes in the sheet conveyed by the first conveying rotor; a sensor that is disposed between the first conveying rotor and the punch member in the sheet conveying direction and changes an output value based on the presence or absence of a sheet at a detection position; a punch motor that is driven based on a detection result of the sensor and drives the punch member; a conveying motor that drives the first conveying rotor and the second conveying rotor; a first drive transmission unit including a first number of drive transmission members for sequentially transmitting a driving force of the transport motor to the first transport rotating body; a second drive transmission unit including a second number of drive transmission members, the second number being greater than the first number, for sequentially transmitting a driving force of the transport motor to the second transport rotating body; the first conveying rotating body and the second conveying rotating body convey the sheet, which is conveyed at a first speed upstream of the first conveying rotating body in the sheet conveying direction, at a second speed faster than the first speed; the first conveying rotating body rotates at a rated speed so as to convey the sheet at the second speed after the leading edge of the sheet has passed the first conveying rotating body and before the leading edge of the sheet reaches the detection position of the sensor; A sheet processing apparatus comprising:

2. a first conveying rotating body that conveys the sheet in a sheet conveying direction; a second conveying rotor disposed downstream of the first conveying rotor in the sheet conveying direction and configured to convey a sheet; a punch member disposed between the first conveying rotor and the second conveying rotor in the sheet conveying direction, the punch member rotating to punch holes in the sheet conveyed by the first conveying rotor; a sensor that is disposed between the first conveying rotor and the punch member in the sheet conveying direction and changes an output value based on the presence or absence of a sheet at a detection position; a punch motor that is driven based on a detection result of the sensor and drives the punch member; a conveying motor that drives the first conveying rotor and the second conveying rotor; A pinion gear fixed to an output shaft of the conveying motor; an output gear fixed to a drive shaft of the first conveying rotor; an idler gear meshing with the pinion gear and the output gear, the first conveying rotating body and the second conveying rotating body convey the sheet, which is conveyed at a first speed upstream of the first conveying rotating body in the sheet conveying direction, at a second speed faster than the first speed; the first conveying rotating body rotates at a rated speed so as to convey the sheet at the second speed after the leading edge of the sheet has passed the first conveying rotating body and before the leading edge of the sheet reaches the detection position of the sensor; A sheet processing apparatus comprising:

3. a first conveying rotating body that conveys the sheet in a sheet conveying direction; a second conveying rotor disposed downstream of the first conveying rotor in the sheet conveying direction and configured to convey a sheet; a punch member disposed between the first conveying rotor and the second conveying rotor in the sheet conveying direction, the punch member rotating to punch holes in the sheet conveyed by the first conveying rotor; a sensor that is disposed between the first conveying rotor and the punch member in the sheet conveying direction and changes an output value based on the presence or absence of a sheet at a detection position; a punch motor that is driven based on a detection result of the sensor and drives the punch member; a conveying motor that drives the first conveying rotor and the second conveying rotor; an output gear fixed to a drive shaft of the first conveying rotor; a gear fixed to an output shaft of the conveying motor and meshing with the output gear; the first conveying rotating body and the second conveying rotating body convey the sheet, which is conveyed at a first speed upstream of the first conveying rotating body in the sheet conveying direction, at a second speed faster than the first speed; the first conveying rotating body rotates at a rated speed so as to convey the sheet at the second speed after the leading edge of the sheet has passed the first conveying rotating body and before the leading edge of the sheet reaches the detection position of the sensor; A sheet processing apparatus comprising:

4. a first conveying path for receiving a sheet; an inverting unit that inverts the sheet received from the first conveying path; a stacking section on which the sheets inverted by the inverting section are stacked; a second conveying path extending below the first conveying path, receiving the sheet inverted by the inverting unit, and guiding the sheet to the stacking unit; a discharge section that discharges the sheet outside the machine; a third conveying path extending from the stacking portion toward the discharge portion and guiding the sheet to the discharge portion; a pair of rotating bodies that are disposed in the second transport path and discharge the sheet to the stacking portion, 4. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is a sheet processing apparatus.

5. The punch member is disposed in the first conveying path.

5. The sheet processing apparatus according to claim 4,

6. The idler gear is a scissors gear having a first gear and a second gear fixed to the first gear in a state where the second gear is out of phase with the first gear.

3. The sheet processing apparatus according to claim 2, wherein the sheet processing apparatus is a sheet processing apparatus.

7. an image forming apparatus for forming an image on a sheet; and a sheet processing apparatus according to claim 1 , which receives a sheet from the image forming apparatus.

1. An image forming system comprising:

8. the image forming apparatus includes a third conveying rotator that transfers a sheet to the first conveying rotator, a motor that drives the third conveying rotator, and a one-way clutch that is provided in a drive transmission path between the motor and the third conveying rotator.

8. The image forming system according to claim 7.

9. A conveying force of the first conveying rotor is greater than a conveying resistance of the third conveying rotor.

9. The image forming system according to claim 8.

Images