JP4522205B2 - Sheet processing apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a sheet processing apparatus and an image forming apparatus including the sheet processing apparatus, and more particularly, to a sheet processing apparatus that waits for a next sheet to be processed while the sheet is being processed.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines, printers, facsimiles, and composite devices of these, a sheet processing apparatus that performs processing such as binding processing on sheets discharged from the image forming apparatus body is provided on the image forming apparatus body. There is something to be provided. In such a sheet processing apparatus, for example, sheets discharged from the main body of the image forming apparatus are stacked on the processing tray, and after the stacked sheets are aligned, processing such as binding processing is performed on the sheets (bundles). I have to.

  By the way, in such a sheet processing apparatus, while processing a sheet, a predetermined number of sheets to be processed next are not directly sent to the processing tray in accordance with the processing time, but are temporarily wound around a buffer roller, There is a configuration in which after waiting for processing, the waiting sheet can be conveyed to a processing tray (see Patent Document 1).

  Further, in such a sheet processing apparatus, the apparatus is reduced in size by branching a plurality of conveyance paths from a buffer roller portion including a buffer roller and conveying the paper to a plurality of paper discharge ports. Furthermore, in an image forming apparatus that discharges to a sheet processing apparatus at a high speed and between a small number of sheets, there is a technique for winding a plurality of sheets around the buffer roller in order to wind the sheet around the buffer roller and save processing time in the processing tray. Are known.

Japanese Patent Laid-Open No. 10-181988

  Incidentally, in recent years, in an image forming apparatus, an image to be formed has shifted from black and white to color, and the types of sheets used have been diversified from thin paper to thick paper.

  However, in the sheet processing apparatus provided in such a conventional image forming apparatus, for example, when a plurality of sheets having a low coefficient of friction μ such as color paper are fed and stacked, in the conventional setting of the clamping pressure in the buffer roller portion, In some cases, the stacked sheets may be misaligned to cause misalignment. If the pressure is increased so as to prevent such misalignment, a conveyance roller mark is generated on the sheet, and an image defect occurs.

  Further, when a stiff sheet such as thick paper is conveyed, the sheet comes into contact with a guide or a flapper outside the buffer roller, the sheet is rubbed, and image defects such as rubbing marks appear on the image. In order to prevent the occurrence of such image defects, for example, when the diameters of the buffer roller and the outer guide are increased, the size of the apparatus is correspondingly increased and the installation property is deteriorated. Further, for example, when the outer guide is a belt, when a plurality of branch paths are provided as in a conventional image forming apparatus, it is necessary to provide a separate transport path, which increases the size and complexity of the apparatus. Connected.

  Accordingly, the present invention has been made in view of such a situation, and an object thereof is to provide a sheet processing apparatus capable of processing a sheet without causing an image defect and an image forming apparatus including the sheet processing apparatus. To do.

According to the present invention, in a sheet processing apparatus that processes a sheet after stacking a sheet on which an image is formed, the sheet stacking unit that stacks the sheet to be processed is disposed upstream of the sheet stacking unit. While the sheet on the sheet stacking unit is being processed, one or more sheets to be processed next are overlapped and waited, and after the processing is completed, the standby sheet is directed to the sheet stacking unit. and a sheet storage means for transporting Te, said sheet storage means, wherein one or a sheet holding means having a sheet suction means for holding by suction a plurality of sheets, the pre-Symbol holding sheets wherein And a moving unit that moves the sheet adsorbing unit in the direction of conveyance toward the sheet stacking unit.

  As in the present invention, while a sheet is being processed, the sheet to be processed next is held by the sheet holding unit, and after the processing is completed, the sheet holding unit is moved by the moving unit, and the held sheet is directed to the sheet stacking unit. By moving the sheet in the conveying direction, the sheet can be processed without causing image defects and without delaying image formation.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet processing apparatus according to a first embodiment of the present invention. In FIG. 1, 300A is an image forming apparatus, and 300 is an image forming apparatus main body ( 1 is a sheet processing apparatus that processes an image-formed sheet discharged from the apparatus main body 300.

  Here, the apparatus main body 300 is provided with a platen glass 301 as a document placement table, a light source 302a, a lens system 302, a paper feeding unit 303, and an image forming unit 304. Further, an automatic document feeder 305 that feeds a document to the platen glass 301 is provided on the upper part of the apparatus main body 300.

  The sheet feeding unit 303 has a cassette 306 that stores recording sheets and is detachable from the apparatus main body 300. The image forming unit 304 includes a cylindrical photosensitive drum 307 and a developing unit 308 disposed around the cylindrical photosensitive drum 307. Further, on the downstream side of the image forming unit 304, a fixing device 309 and a discharge roller pair. 310 etc. are arranged.

  Next, an image forming operation of the apparatus main body 300 having such a configuration will be described.

  When a paper feed signal is output from the apparatus main body 300, a sheet is fed from the cassette 306, and light reflected from the original after being applied to the original placed on the platen glass 301 from the light source 302a is reflected. The photosensitive drum 307 is irradiated through the lens system 302. At this time, the surface of the photosensitive drum 307 is uniformly charged in advance. When light is irradiated in this way, an electrostatic latent image is formed on the surface, and then the electrostatic latent image is developed by the developing device 308. As a result, a toner image is formed on the surface.

  On the other hand, the sheet fed from the sheet feeding unit 303 is corrected for skew by the registration roller 311, and then conveyed to the image forming unit 304 at the right timing to form an image. The sheet on which the image is thus formed is permanently fixed on the transfer image by the fixing device 309. Thereafter, the sheet on which the image is fixed in this manner is discharged from the apparatus main body 300 by the discharge roller pair 310. The sheet is discharged toward the sheet processing apparatus 1. In this way, the sheet fed from the sheet feeding unit 303 is discharged toward the sheet processing apparatus 1 after an image is formed.

  The sheet processing apparatus 1 includes a buffer roller unit 3, a processing tray unit 129 including a processing tray 130 as a sheet stacking unit, which will be described later, and the like.

  Here, the buffer roller unit 3 is arranged upstream of the processing tray 130, and while the sheet on the processing tray 130 is being processed, the next or one or more sheets to be processed are overlapped to wait. After the processing is completed, a sheet storage unit that conveys the waiting sheet toward the processing tray 130 is configured.

  Note that the number of sheets to be overlapped and waiting is determined by the balance between the image forming speed in the apparatus main body 300 and the sheet processing speed in the sheet processing apparatus 1. In other words, the sheet from the buffer roller unit 3 is set so as not to interfere with the sheet being processed on the processing tray 130 and the time when there is no sheet to be processed on the processing tray 130 does not become longer than necessary. The By doing so, the total time required from image formation to sheet processing is shortened.

  Then, the buffer roller unit 3 as the sheet storage unit moves the sheet holding unit that holds one or a plurality of sheets, and the sheet holding unit in a direction in which the held sheet is conveyed toward the processing tray 130. And moving means. In the present embodiment, the sheet holding means is made of a dielectric sheet as shown in FIG. 2, and an adsorption belt 11 as a sheet adsorption means that is an endless belt member that adsorbs and conveys the sheet, and an adsorption belt. 11 is constituted by a charging roller 14 or the like that is arranged in contact with the suction belt 11 and applies a charge to the suction belt 11, and the moving means is a driving roller 12 as a rotating member around which the suction belt 11 is wound and rotated from a driving source (not shown). And the tension roller 13 and the outer guides 16 and 24.

  In FIG. 2, 15 is an AC power source, 26 is a changeover switch, and 25 is a CPU which is a control means for controlling the switching operation of the changeover switch 26, the output from the AC power supply 15, and the like. After the image is formed, the discharged sheet enters the sheet processing apparatus 1 and is then conveyed downstream by the entrance roller pair 2 (see FIG. 1), and the sheet detection sensor 40 detects this sheet. Then, the CPU 25 turns on the changeover switch 26.

  As a result, a high voltage is applied to the charging roller 14 from the AC power supply 15, and an electric field is generated on the suction belt 11. As a result, an adsorption force that attracts the sheet is generated on the adsorption belt 11. 11 adsorbs the sheet. After the sheet is sucked in this way, the sheet is sucked and conveyed by the suction belt 11 when the driving roller 12 rotates in the direction of the arrow.

  In FIG. 2, 17, 18, and 19 are rotatable auxiliary rollers, and the auxiliary rollers 17, 18, and 19 are in contact with the suction belt 11 with a predetermined pressure. Here, the auxiliary rollers 17, 18, and 19 are merely for assisting conveyance, and pressure is not applied to cause image defects, and may be omitted.

  Further, the auxiliary rollers 17, 18, and 19 may be used as an electric field removing roller. In this case, if the same structure as that of the charging roller 14 is provided to remove the electric field, a flapper described later is used. The branching at 4 and 5 can be performed smoothly, which is effective in preventing image rubbing (image failure) at the flappers 4 and 5.

  In FIG. 2, 4 is a first switching flapper for switching between the non-sorting path 21 and the sorting path 22, and 5 is a second switching flapper for switching between the sorting path 22 and the buffer path 23 for temporarily storing sheets. is there. The non-sort path 21 is provided with a trailing edge detection sensor 33 (see FIG. 1) that detects the trailing edge of the sheet P.

  Further, the sort path 22 is provided with a sheet conveying section 32A as shown in FIG. Here, the sheet conveying unit 32A includes a conveying roller 32 that is rotated by a driving source (not shown), and a conveying belt 30 that is supported by the driving roller 31 and the supporting roller 33 and is pressed against the conveying roller 32. Yes. The sheets conveyed to the sort path 22 by the sheet conveying unit 32A are conveyed to a discharge roller pair 6 described later.

  Since the sheet conveying unit 32A has no branch path, an image defect or the like does not occur even when the conveying belt 30 is a normal conveying belt. This is preferable because the conveyance performance is increased. Further, the belt 30 may extend to the paper discharge roller 6.

  In FIG. 3, reference numeral 35 denotes a static elimination needle. By removing static electricity charged on the sheet by the static elimination needle 35, the static electricity is not affected when the sheets are aligned on the processing tray.

  On the other hand, as shown in FIG. 1, the processing tray unit 129 temporarily stacks sheets, processes a tray (intermediate tray) 130 as a sheet stacking unit for performing alignment and stapling, and sheets on the processing tray 130. A discharge roller (discharge unit) 6 for discharging, an aligning unit 140, a return belt 160, a staple unit 100 that staples the sheet bundle stacked on the processing tray 130 as necessary, and the like are provided.

  Here, the processing tray 130 is an inclined tray with the downstream side (left in the figure) upward and the upstream side (right in the figure) downward, and a rear end stopper 131 is disposed at the upstream end. Yes. The sheet P discharged by the discharge roller pair 6 slides on the processing tray 130 until its rear end comes into contact with the rear end stopper 131 due to its own weight and the action of the return belt 160. The rear end stopper 131 of the processing tray 130 and the stapler (not shown) of the staple unit 100 are normally waiting at the home position (the front side in FIG. 1 in the present embodiment).

  The aligning means 140 is composed of an aligning member that is disposed in front and back of the drawing and can move independently in the direction orthogonal to the transport direction, and performs alignment in the direction orthogonal to the transport direction.

  Reference numeral 150 denotes a swing guide, and 180b denotes an upper roller supported by the swing guide 150. The upper roller 180b swings downward when the swing guide 150 moves to the closed position. A bundle discharge roller pair for conveying a bundle of sheets on the processing tray 130 and discharging the bundle onto the stack tray 200 in cooperation with the lower roller 180a disposed on the stack tray 200 is configured.

  Here, when the sheets are discharged to the processing tray 130 one by one, the swing guide 150 does not interfere with the discharge and dropping of the sheets to the processing tray 130 and the subsequent alignment operation. As shown in FIG. 1, when the bundle is discharged from the processing tray 130 to the stack tray 200 (a state where the upper discharge roller 180b is in contact with the sheet), the opening state (a state where the pair of bundle discharge rollers 180a and 180b are separated) is achieved. )

  In FIG. 1, reference numeral 200 denotes a stack tray, and 201 denotes a sample tray. These two trays 200 and 201 can be used properly depending on the situation. For example, the lower stack tray 200 is selected when receiving copy output, printer output, and the like, and the upper sample tray 201 is sample output, interrupt output, stack tray overflow output, function sorting output, and job loading It will be selected when receiving output, etc.

  The two trays 200 and 201 are both supported so that they can independently run in the vertical direction. Further, as a method of detecting the paper surface, each paper surface detection sensor 203 shown in FIG. 4 is provided, and the CPU 25 controls the height of the trays 200 and 201 based on a signal from the paper surface detection sensor 203. .

  Next, the flow of the sheet P in the sheet processing apparatus 1 configured as described above will be described.

  When the user designates the non-sort mode by an operation unit (not shown) of the apparatus main body 300, the entrance roller pair 2 and the driving roller 12 rotate, and the suction belt 11 rotates accordingly. Further, the changeover switch 26 is turned on by the CPU 25, whereby a high voltage is applied to the charging roller 14 from the AC power supply 15 to generate an electric field on the suction belt 11, and the sheet is sucked onto the suction belt 11 by its action.

  Then, after the sheet is sucked in this way, when the driving roller 12 rotates, the sheet is sucked and conveyed by the suction belt 11. At this time, the first switching flapper 4 is switched in the direction in which the sheet P is conveyed to the non-sorting path 21 by the action of a solenoid (not shown).

  When the first switching flapper 4 is switched in this way, the sheet P is conveyed to the non-sort path 21. Thereafter, when the trailing edge detection sensor 33 detects the trailing edge of the sheet P, the discharge roller 9 is The sheet P rotates at a speed suitable for stacking, and the sheet P is discharged onto the sample tray 200. At this time, the auxiliary roller 18 may function as an electric field removing unit so that the sheet can be smoothly branched by the flapper 4.

  On the other hand, when the user designates the staple sort mode, the suction belt 11 rotates with the rotation of the entrance roller pair 2 and the drive roller 12, and the sheet P conveyed from the apparatus main body 300 is conveyed. At this time, by applying a high voltage to the charging roller 14, an electric field is generated on the suction belt 11, and the sheet is sucked and conveyed.

  Thereafter, the sheet P sucked and transported is switched to the position shown in FIG. 3 of the second switching flapper 5 and the sheet held by the suction belt 11 of the driving roller 12 indicated by the arrow is transported toward the processing tray 130. It is sent to the sort path 22 by rotation in the direction. At this time, the second auxiliary roller 19 may function as an electric field removing unit so that the sheet P can be smoothly branched by the second switching flapper 5.

  Next, the sheet P sent to the sort path 22 in this way is sent to the paper discharge roller 6 and discharged onto the processing tray 130, and starts moving on the processing tray 130 toward the rear end stopper 131 by its own weight. The sheets discharged together with the return belt 160 are aligned. When all the first sheets are discharged onto the processing tray 130 and aligned, the swing guide 150 is lowered and the upper roller 180b is placed on the sheet bundle, and the staple unit 100 staples the sheet bundle. . The sheet bundle processed on the processing tray 130 in this manner is discharged onto the stack tray 200.

  By the way, during such sheet processing, the first sheet P1 of the next job (second copy) discharged from the apparatus main body 300 is adsorbed with an electric field formed as shown in FIG. When the next sheet P2 is wound around the belt 11 and advances a predetermined distance from the sheet detection sensor 40, as shown in FIG. 5 (b), the suction belt 11 is rotated and the second sheet from the first sheet P1 is rotated. The sheets P2 are overlaid so that the sheet P2 is ahead by a predetermined distance. By superimposing in this way, the leading edge of the second sheet P2 does not overlap the first sheet P1, but directly contacts the suction belt 11, so that a stronger suction force can be obtained. It becomes possible to maintain a stable posture.

  Further, after that, when the third sheet P3 advances a predetermined distance from the sheet detection sensor 40, the suction belt 11 rotates as shown in FIG. 6A, and the third sheet P3 is rotated from the second sheet P2. The sheets P3 are overlaid so that they are preceded by a predetermined distance. FIG. 6B is an enlarged view showing a state in which the third sheet P3 is overlaid so as to precede the first and second sheets P1 and P2. Since the third sheet P3 is also in direct contact with the suction belt 11, a stronger suction force can be obtained, and the three stacked sheets can maintain a stable posture.

  Here, in the present embodiment, it is assumed that the sheet processing is completed while the buffer roller unit 3 buffers the three sheets P1 to P3. For this reason, when the sheet processing is completed, the three sheets P1 to P3 waiting in the buffer roller unit 3 are switched to the position shown in FIG. Then, they are collectively conveyed onto the processing tray 130.

  In this manner, when the three sheets P1 to P3 are discharged onto the processing tray 130 with their respective leading ends shifted, the three sheets P1 to P3 are moved on the processing tray 130 by their own weight while overlapping. First, the lowermost sheet P1 hits the rear end stopper 131, and then the return belt 160 acts on the uppermost sheet P3 and moves toward the rear end stopper 131.

  The second sheet P2 moves together with the lowermost sheet P1 due to the frictional action with the lowermost sheet P1, and hits the rear end stopper 131 in the order of the sheet P2 and then the sheet P1, and is aligned. If the leading edge displacement direction is opposite, the alignment operation ends when the uppermost sheet P3 hits the trailing edge stopper 131, and the remaining sheets P1 and P2 are stacked while being shifted.

  Thereafter, the fourth and subsequent sheets P are discharged onto the processing tray through the sort path 22 as in the first copy operation. For the third and subsequent copies, the same operation as that for the second copy is performed. After that, when a set number of sheet bundles are stacked on the stack tray 200, the staple sort mode ends.

  Here, in this embodiment, three sheets are stacked, but four or more sheets may be stacked depending on the configuration of the apparatus main body. The number of sheets to be buffered is determined by the balance between the image forming speed in the apparatus main body 300 and the sheet processing speed in the sheet processing apparatus 1. In other words, the sheet from the buffer roller unit 3 is set so as not to interfere with the sheet being processed on the processing tray 130 and the time when there is no sheet to be processed on the processing tray 130 does not become longer than necessary. The By doing so, the total time required from image formation to sheet processing is shortened. In the sort mode, which is another mode, the stapling operation is not performed, but substantially the same operation as the stapling mode is performed.

  By the way, as in the present embodiment, the suction belt 11 holds one sheet or a plurality of sheets, and the suction belt 11 that sucks the sheets in this way is moved toward the processing tray by the driving roller 12. Even when a plurality of sheets having a low coefficient of friction μ such as color paper are sent in a stacked manner, the stacked sheets are not displaced from each other, and good alignment can be achieved.

  Further, while the sheets are being processed in this way, one or a plurality of sheets to be processed next are overlapped and held on the suction belt 11, and after the processing, the suction belt 11 is moved to the processing tray by the driving roller 12. Unlike the case of using a pair of conveying rollers, the sheet can be conveyed without increasing the pressure, so that no conveying roller trace is generated and image defects can be prevented. Further, even when a stiff sheet such as thick paper is conveyed, the image is defective such that the sheet is rubbed on the guides 16 and 24 and the flappers 4 and 5 outside the rollers 12 and 13 to cause rubbing marks on the image. Can be prevented.

  Further, since it is not necessary to increase the diameters of the rollers 12 and 13 and the outer guides 16 and 24, the apparatus can be prevented from being enlarged, and the installation property is not deteriorated.

  In FIG. 2, reference numeral 20 denotes a displacement sensor which is a suction state detecting means for detecting the suction state of the sheet to the suction belt 11, and based on the signal from the displacement sensor 20, that is, its displacement amount (suction). The CPU 25 adjusts the AC power supply 16 according to the amount, and controls the voltage applied to the charging roller 14.

  For example, the CPU 25 determines the electrostatic attraction force (amount of static electricity) when the displacement of the sheet is determined to be based on the signal from the displacement sensor 20 and the sheet is separated from the adsorption belt 11 and is in contact with the outer guide 16. The voltage applied to the charging roller 14 is increased so as to increase the voltage.

  In FIG. 4, 204 is a sheet identifying means for identifying or setting the sheet type, and the CPU 25 applies it to the charging roller 14 based on the sheet type information identified or set by the sheet identifying means 204. The voltage to be controlled is controlled. For example, when the sheet is thick paper, the voltage applied to the charging roller 14 is increased so as to increase the electrostatic attraction force.

  And by performing such control, a diversified material such as color paper and cardboard is surely buffered to ensure productivity, and a sheet processing apparatus that does not cause image defects and an image forming apparatus including the sheet processing apparatus are provided. Can be provided.

Next, reference examples of the present invention will be described.

Figure 7 is a diagram showing a schematic configuration of an image forming apparatus including a sheet processing apparatus according to the present embodiment, FIG. 8 is a diagram showing a configuration of a buffer roller unit of the sheet processing apparatus according to the present embodiment. In FIG. 7, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. In FIG. 8, the same reference numerals as those in FIG. 2 denote the same or corresponding parts.

  7 and 8, reference numeral 50 denotes a gripper that is provided in the buffer roller unit 3 and constitutes a sheet holding unit. The gripper 50 is provided in a buffer roller 51 that is an example of a rotating member that constitutes a moving unit. It rotates integrally with a buffer roller 51 that is driven to rotate by a drive source (not shown).

  Here, the gripper 50 is configured to hold a sheet by a gripper driving means (not shown) (solid line state at the upper right in FIG. 7) and a first retraction position for receiving the sheet (broken line state at the upper right in FIG. 7). And is configured to be movable to a second retracted position (lower left state in FIG. 7) for releasing the sheet held by the rotation of the buffer roller 51.

  Next, the sheet storing operation of the buffer roller unit 3 having such a configuration will be described.

  As described above, when the sheet detection sensor 40 detects the first sheet P1 discharged from the apparatus main body 300 while processing the sheet on the processing tray, the gripper 50 detects the first sheet P1 at a predetermined timing. The sheet P1 is moved from the retracted position to the sheet holding position as shown in FIG.

  Then, after holding the first sheet P1 in this way, the buffer roller 51 rotates. Thus, the sheet P1 is conveyed while being wound around the buffer roller 51 while being held by the gripper 50. Thereafter, when the next sheet is conveyed, as shown in FIG. 9B, the next sheet P <b> 2 and the sheet P <b> 1 conveyed while being wound around the buffer roller 51 are overlapped. Once the rotation of the buffer roller 51 is stopped at a predetermined position, the sheet P2 is similarly held by the gripper 50.

  After that, the overlapped sheets are opened at the leading edge by the retracting of the gripper 50 to the second retracted position in front of the flapper 5 switched as shown in FIG. You will be guided to 22.

  In this way, by holding (holding) one sheet or a plurality of sheets by the gripper 50 and moving (rotating) the gripper 50 holding the sheets in this way toward the processing tray together with the buffer roller 51, Even when a plurality of sheets having a low friction coefficient μ such as colored paper are sent in a stacked manner, the stacked sheets are not displaced from each other, and good alignment can be achieved.

In the case of the present reference example , since the sheet is not charged, it is not necessary to be affected by charging at the time of alignment on the processing tray 130, and thus a configuration such as electrostatic removal becomes unnecessary.

Next, a description will be given of a second embodiment of the present invention.

  FIG. 10 is a diagram illustrating a configuration of the buffer roller unit of the sheet processing apparatus according to the present embodiment. In FIG. 10, the same reference numerals as those in FIG. 8 denote the same or corresponding parts.

  In FIG. 10, reference numeral 60 denotes a suction fan that is an example of a sheet suction unit that is provided in the buffer roller unit 3 and constitutes a sheet holding unit. The suction fan 60 is rotated by a driving unit (not shown) to generate a negative pressure. Generated and sucked and held by the sheet.

  The suction fan 60 is provided on a buffer roller 51 that is an example of a rotating member that constitutes a moving unit, and rotates integrally with the buffer roller 51 that is rotationally driven by a drive source (not shown). As the buffer roller 51 rotates, it is configured to be movable between a position where the sheet is sucked and held (lower left state in FIG. 10) and an open position where the sucked and held sheet is released (lower left state in FIG. 10). Has been.

  Next, the sheet storing operation of the buffer roller unit 3 having such a configuration will be described.

  As described above, while the sheet on the processing tray is being processed, when the sheet detection sensor 40 detects the first sheet P1 discharged from the apparatus main body 300, the suction fan 60 rotates to hold the sheet by suction. To do.

  After the sheet is sucked and held in this way, the buffer roller 51 rotates. As a result, the sheet is conveyed while being wound around the buffer roller 51 while being sucked by the suction fan 60.

  Thereafter, when the next sheet is conveyed, the suction fan 60 once reaches a predetermined position indicated by a solid line in FIG. 10 in order to superimpose the next sheet P2 and the sheet P1 being rotated and conveyed. At this time, the rotation operation of the buffer roller 51 is stopped, and the second sheet P2 is sucked and held by the suction fan 60. Further, thereafter, the third sheet P3 is similarly sucked and held by the suction fan 60.

  In the present embodiment, the third sheet P3 precedes the first and second sheets P1 and P2 as shown in FIG. 11 so that the three sheets P1 to P3 can be sucked and conveyed. So that they overlap.

  After that, the stacked sheets P1 to P3 are opened at the front end by stopping the suction fan 60 at a predetermined position in front of the second switching flapper 5 indicated by a broken line in FIG. You will be guided to 22.

  Thus, by sucking and holding one sheet or a plurality of sheets by the suction fan 60, the suction fan 60 holding the sheet in this way is moved (rotated) toward the processing tray together with the buffer roller 51, Even when a plurality of sheets having a low friction coefficient μ such as colored paper are sent in a stacked manner, the stacked sheets are not displaced from each other, and good alignment can be achieved.

  In the present embodiment, since the sheet is not charged, it is not necessary to be affected by charging at the time of alignment on the processing tray 130, and thus a configuration such as electrostatic removal becomes unnecessary.

1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet processing apparatus according to a first embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a buffer roller unit provided in the sheet processing apparatus. FIG. 3 is a diagram illustrating a configuration of a sheet conveying unit provided in the sheet processing apparatus. FIG. 3 is a control block diagram of the sheet processing apparatus. The 1st figure explaining the buffer operation | movement of the said buffer roller part. The 2nd figure explaining the buffer operation | movement of the said buffer roller part. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet processing apparatus according to a reference example of the present invention. FIG. 3 is a diagram illustrating a configuration of a buffer roller unit provided in the sheet processing apparatus. The figure explaining the buffer operation | movement of the said buffer roller part. The figure explaining the structure of the buffer roller part provided in the sheet processing apparatus which concerns on the 2nd Embodiment of this invention. FIG. 6 is a diagram illustrating a sheet conveyance state during a buffer operation of the buffer roller unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sheet processing apparatus 3 Buffer roller part 11 Adsorption belt 12 Drive roller 13 Stretch roller 14 Charging roller 15 AC power supply 20 Displacement sensor 25 CPU
26 switch 50 gripper 51 buffer roller 60 suction fan 130 processing tray 204 sheet identification means 300A image forming apparatus 300 image forming apparatus main body 304 image forming unit P sheet

Claims (8)

In a sheet processing apparatus that performs processing on the sheet after stacking sheets on which images are formed,
Sheet stacking means for stacking sheets to be processed;
While the sheet on the sheet stacking unit is disposed upstream of the sheet stacking unit and is processed, one or more sheets to be processed next are overlapped and waited, and after the processing is completed, the standby is performed. Sheet storage means for transporting the collected sheets toward the sheet stacking means,
The sheet storage means includes a sheet holding means having a sheet suction means for sucking and holding the one sheet or a plurality of sheets, and the sheet in a direction in which the held sheet is conveyed toward the sheet stacking means. A sheet processing apparatus comprising: a moving unit that moves the suction unit.   The sheet processing apparatus according to claim 1, wherein the moving unit includes a rotating member that rotates the sheet adsorbing unit in a direction in which the held sheet is conveyed toward the sheet stacking unit.   The sheet processing apparatus according to claim 2, wherein the sheet storage unit rotates the sheet suction unit by the rotating member to sequentially stack and suck a predetermined number of sheets.   The sheet processing apparatus according to claim 3, wherein the sheet storage unit stacks a predetermined number of sheets sequentially and adsorbs the sheets stacked from above so as to precede by a predetermined distance. Control means for controlling the magnitude of the sheet suction force of the sheet suction means;
At least one of a sheet identification unit for identifying or setting the type of the sheet and a suction state detection unit for detecting a suction state of the sheet sucked by the sheet suction unit with respect to the sheet suction unit;
With
5. The control unit according to claim 1, wherein the control unit controls the magnitude of the sheet suction force of the sheet suction unit based on information from at least one of the sheet identification unit and the suction state detection unit. The sheet processing apparatus according to claim 1.   The sheet adsorbing means is an endless belt member that adsorbs and holds the one sheet or a plurality of sheets by static electricity, and the control means includes at least one of the sheet identifying means and the adsorbing state detecting means. 6. The sheet processing apparatus according to claim 5, wherein an amount of static electricity applied to the endless belt member is controlled based on the information.   6. The sheet processing apparatus according to claim 5, wherein the sheet adsorbing means is a fan that adsorbs and holds the one sheet or a plurality of sheets with air.   An image comprising: an image forming unit that forms an image on a sheet; and the sheet processing apparatus according to claim 1 that processes the sheet on which an image is formed by the image forming unit. Forming equipment.

Images