JP2007314276A - Post-processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a post-processing device capable of accurately detecting the position of a projection part without erroneous detection of the projection part on a belt by an optical sensor. <P>SOLUTION: The post-processing device is provided with a projection part (a bundle lowering member 32) provided in a second belt 31 to be driven for normal and reverse rotation in a processing unit 5, the optical sensor 36 for detecting position of the projection part, and a guide 37 provided at a position on a depth side of the projection part (the bundle lowering member 32) in the radiating direction of the optical sensor 36 to shut out the light of the optical sensor 36 and to prevent vibration of the projection part (the bundle lowering member 32). With this structure, even if a member except the projection part (the bundle lowering member 32) as an object of position detection exists in a detection range S of the optical sensor 36, the guide 37 shuts out the light to prevent erroneous detection by the optical sensor. Furthermore, vibration of the belt during rotation can be prevented by the guide 37. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a post-processing apparatus configured to perform predetermined post-processing on a sheet or the like supplied from an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and then discharge the paper.

  Conventionally, a post-processing device (image) that aligns sheets on which an image is formed and performs predetermined processing such as stapling, punching (punching) processing, and half-folding (half-folding) processing according to a user's designation. 2. Description of the Related Art A post-processing apparatus) is known and used (see Patent Document 1).

  A post-processing device described in Patent Document 1 includes a processing tray that temporarily stores a sheet on which an image has been formed, a binding processing unit that can perform a stapling process on one side end of the sheet, and an endless belt that binds the bound sheet bundle. A protrusion (discharge means) that discharges by a discharge claw provided in the head is provided, and the protrusion moves preliminarily prior to the discharge operation, thereby shortening the time required to discharge the sheet bundle.

  Further, in addition to the endless belt provided with the protruding portion for discharging the paper as described above, another post-end belt provided with the protruding portion mainly for aligning the paper is provided. An apparatus is also known (see Patent Document 2).

The post-processing device described in Patent Document 2 is capable of stacking and stapling sheets, has an endless belt having a protrusion for receiving the leading edge of the sheet, and a protrusion that is used mainly for alignment of the sheet separately. An endless belt provided with a portion is provided. Each of the paper alignment protrusions aligns the paper by rotating the belt provided with the protrusions in conjunction with the stacking of the paper and pressing the trailing edge of the paper.
Japanese Patent Laid-Open No. 11-60038 JP 2002-154739 A

  As described above, the post-processing apparatus is generally provided with an endless belt provided with protrusions, and the protrusions are used for stacking and aligning sheets, but each process in the post-processing apparatus is accurately performed. For this purpose, it is necessary to accurately detect the positions of these protrusions. This is because, for each process, it is necessary to rotate the belt by a predetermined amount for each paper size and each process, but the amount by which the belt is rotated is determined based on the detected position of the protrusion.

  And in the post-processing apparatus provided with the two endless belts as in the invention described in Patent Document 2, when the two endless belts are arranged side by side or close to each other (see FIG. 4), the protruding portion is formed by the optical sensor. If an attempt is made to detect the position, there is a problem that the optical sensor may erroneously detect. This is because, due to this arrangement, both of the two protrusions enter the detection range of the optical sensor, and the optical sensor may also detect a protrusion that is different from the protrusion that is originally desired to be detected.

  In general, the belt is rotated in the forward and reverse directions and may be rotated at a high speed. Therefore, the detection accuracy of the sensor is detected by the protrusion swinging in a direction perpendicular to the rotation direction of the belt. There is a problem of falling. This causes, for example, excessive pressing or insufficient pressing of the sheet when aligning the sheets.

  Here, the post-processing apparatus described in Patent Document 1 uses a sensor with a filler (see Patent Document 1, Paragraph 0008) as a means for detecting the position of the protrusion (ejecting means) on the belt. Only one endless belt is provided, and the problem of false detection due to having two protrusions cannot occur. Moreover, since the patent document 2 does not describe the position detection means of the protrusion, the above problem cannot be solved.

  The present invention has been made in view of the above-described problems of the prior art, and the sensor does not erroneously detect the protruding portion, and can detect the position of the protruding portion with high accuracy. It is an object of the present invention to provide a post-processing apparatus that can accurately perform the above.

  According to the first aspect of the present invention, the sheet discharged from the image forming apparatus is received in the apparatus main body through the carry-in port, and the sheet is transported in the apparatus and subjected to a predetermined process. Is disposed in the tray, a processing unit for stacking a plurality of sheets and performing the predetermined processing is provided in the post-processing device, and the processing unit can be rotated forward and backward. A protrusion provided on an endless belt that is driven to rotate, a light sensor for detecting the position of the protrusion, and the position of the light sensor in the irradiation direction of the light sensor relative to the protrusion. A guide is provided to block light and prevent the protrusion from shaking.

  According to a second aspect of the present invention, in the post-processing apparatus according to the first aspect, the guide is a matte black member.

  According to a third aspect of the present invention, in the post-processing apparatus according to the first or second aspect, the protruding portion presses the end of the sheet from above by forward / reverse rotation of the belt every time one sheet is stacked. Therefore, it is a bundle lowering member that aligns the sheets.

  According to the first aspect of the present invention, the sheet discharged from the image forming apparatus is received in the apparatus main body through the carry-in port, and the sheet is transported in the apparatus and subjected to a predetermined process. In the post-processing device in which the paper is discharged to the tray, a processing unit is provided in the post-processing device for stacking a plurality of sheets and performing a predetermined processing, and the processing unit can be rotated forward and backward. A protrusion provided on an endless belt that is driven to rotate, a light sensor for detecting the position of the protrusion, and the position of the light sensor in the irradiation direction of the light sensor relative to the protrusion. Since the guide is provided to block the light and prevent the protrusion from shaking, even if there is a member other than the protrusion whose position is to be detected in the detection range of the sensor, the guide emits the light from the sensor. Whether to shade , The sensor is unnecessary to false positives. Further, since the protrusion is prevented from shaking during rotation of the belt by the guide, the sensor does not vary in detecting the position of the protrusion and can be detected with high accuracy.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, since the guide is a matte black member, it is easy to use a matte black material or to paint matte black. By this method, the light of the photosensor can be surely shielded.

  According to the invention of claim 3, the protrusion is a bundle-lowering member that aligns the paper by pressing the paper edge from above by forward / reverse rotation of the belt each time one paper is stacked. The paper can be aligned after the position of the protrusion is accurately detected, and the paper is not overpressed or insufficiently pressed.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, the outline of the post-processing apparatus 1 in the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a sectional view seen from the front showing a schematic configuration of a post-processing apparatus 1 according to an embodiment of the present invention.

  As shown in FIG. 1, the post-processing apparatus 1 is provided on the side of the image forming apparatus 2, and its outer shape is partitioned by a housing 3. In the housing 3, a punch unit 4, a processing unit 5, a middle folding unit 6, and the like are provided. The processing unit 5 stacks a plurality of sheets, stacks a front end of the stacked bundle of sheets P with staples, and binds with two staples in the vertical direction at the center in the longitudinal direction of the bundle of sheets P. Staple processing such as center binding can be executed.

  The punch unit 4 is for performing punch processing for making holes at predetermined positions on the paper conveyed from the image forming apparatus 2. The center folding unit 6 is for folding the sheet bundle P, which is bound in the center by the stapling process, along the staples at the center.

  Here, the predetermined process in the post-processing apparatus 1 will be described.

  The paper discharged from the image forming apparatus 2 is carried into the post-processing apparatus 1 through the carry-in port 7 provided on the side surface of the housing 3, and conveyed to the punch unit 4 through the conveyance path 8. When punching is selected, a hole is made at a predetermined position of the paper in the punch unit 4. When punching is not selected, the sheet passes through the punch unit 4 without being punched.

  The standby drum 9 provided downstream of the punch unit 4 in the paper conveyance direction rotates clockwise in FIG. 1, and when the staple processing is performed on the plurality of paper bundles P, the front unit is the staple unit in the processing unit 5. While this is being done, the first sheet of the next part is wound around the drum surface and waited. By the operation of the standby drum 9, it is not necessary to temporarily stop the next sheet from being discharged from the image forming apparatus 2 during the stapling process.

  When the stack processing and the staple processing are not selected, the plurality of separation claws 10 that are rotatably held are sent to the discharge roller pair 11 and discharged to the discharge tray 12. Above the discharge tray 12, a plurality of job trays 13 are arranged side by side in the housing 3 protruding upward. These job trays 13 can be moved individually or integrally in the vertical direction. Any job tray 13 can be opposed to the discharge roller pair 11 and the discharged paper can be distributed to any job tray 13. . Paper that has not been stapled may be distributed to these job trays 13 and discharged.

  On the other hand, when the stack process or the staple process is selected, the sheet is conveyed downward by the conveyance roller pair 8 a and is sent to the processing unit 5. The processing unit 5 includes an upper unit 14 and a lower unit 15, and the conveyed paper is passed between the upper unit 14 and the lower unit 15.

  The processing unit 5 stacks a plurality of sheets, stacks the leading ends of the stacked sheet bundles P with staples, and staples the center of the sheet bundle P in the longitudinal direction with two staples along the short direction. Staple processing such as center binding can be performed. The front end binding includes front end center binding in which the vicinity of the center of the front end of the sheet bundle P is bound along the longitudinal direction, and front end slant binding in which one corner of the front end of the sheet bundle P is bound at 45 ° diagonally. It is. The sheet bundle P that has been subjected to the stacking process or the front end binding is conveyed upward, sorted by the discharge roller pair 11 to the discharge tray 12 or the job tray 13 and discharged.

  Below the processing unit 5, a middle folding unit 6 is disposed for performing a folding process in which the center-bound paper bundle P is folded along the staples at the center. When the folding process is selected, the sheet bundle P on which the center binding is performed is conveyed to the middle folding unit 6, and the folded booklet sheet bundle P is a booklet provided at the lower part of the housing 3. It is discharged to the tray 16. When the folding process is not selected, the sheet bundle P subjected to the center binding is conveyed to the discharge roller pair 11 and discharged to the discharge tray 12 or the job tray 13.

  Next, an outline of the sheet transport mechanism of the lower unit 15 in the post-processing apparatus 1 will be described with reference to FIG. FIG. 2 is a schematic perspective view showing the paper transport mechanism of the lower unit 15 of the post-processing apparatus 1 according to this embodiment.

  As shown in FIG. 2, the lower unit 15 has an intermediate tray 23 disposed between a pair of left and right side plates 21 and 22. The sheet sent to the processing unit 5 passes between the upper unit 14 and the lower unit 15, and the leading end of the intermediate tray 23 is formed by a bundle-up member 25 whose front end forms a U-shaped pair of lower units 15. Received on the surface.

  The bundling members 25 are attached to a pair of endless first belts 26 disposed substantially at the center in the width direction of the lower unit 15, and the first belt from one bundling member 25 to the other bundling member 25. 26 so that the distances on 26 are equal to each other. The pair of bundling members 25 stands by so that the rear end of the paper, that is, the upper end of the paper is stacked at a certain position, corresponding to the size of the paper to be used. The other bundle raising member 25 (not visible in FIG. 2) is stopped at the reference position on the back side of the intermediate tray 23 (the side not protruding from the surface of the intermediate tray 23).

  The lower unit 15 is provided with a rotary shaft 27 at the upper end and a rotary shaft 28 (drive rotary shaft) at the lower end, and the first belt 26 is wound around the drive shaft. A pulley belt 29b is wound around the rotary shaft 28 at the lower end portion between the rotary shaft 29a of the motor M1. When the motor M1 is rotationally driven so as to be rotatable forward and backward, the first belt 26 is rotated forward and backward via the pulley belt 29b and the rotating shaft 28.

  In addition, a rotation shaft 30 is provided slightly below the center of the lower unit 15 and on the back side of the intermediate tray. The rotation shaft 27 and the rotation shaft 30 are arranged along the center line of the lower unit 15. The endless second belt 31 is wound around. The front side of the second belt 31 faces the conveyance path on the front side of the intermediate tray 23, and the rear side passes through the back side of the intermediate tray 23. Note that a bundle lowering member 32 (see FIGS. 3 and 4) protrudes outwardly on the back side of the intermediate tray 23 as a protrusion on the second belt 31 that is driven to rotate forward and backward. And is stopped at a reference position described later.

  The lower unit 15 is provided with a pair of paper guides 33 for aligning the paper in the transport direction. The pair of paper guides 33 are juxtaposed in the width direction of the lower unit 15 and extend in parallel to the center line from the upper end of the lower unit 15 to the vicinity of the center. Each paper guide 33 is attached so as to be individually movable in the width direction of the lower unit 15 and symmetrically stands by at a position corresponding to the size of the paper to be used.

  When the stacking of a predetermined number of sheets is completed by the mechanism as described above, stapling processing is performed on the stacked sheet bundle P by the stapling means 17 and the staple receiving means 18 (see FIG. 1). When the stapling process is completed, the first belt 26 is rotated in the direction in which the sheet bundle P is conveyed upward, and the bundle raising member 25 pushes the leading end of the sheet bundle P upward. The bundle raising member 25 causes the rear end of the sheet bundle P to reach the discharge roller pair 11 and the sheet bundle P is reliably discharged (see FIG. 1).

  On the other hand, when the folding process is selected, when the stapling process is completed, the first belt 26 and the second belt 31 are again rotated in synchronization with the direction in which the sheet bundle P is conveyed downward. The sheet bundle P is supported by the bundle raising member 25 at the front end and the bundle lowering member 32 at the rear end, and is conveyed downward. When the leading end of the sheet bundle P reaches a pair of conveying roller pairs 34 provided near the lower ends of the upper unit 14 and the lower unit 15, the sheet bundle P is conveyed downward by the conveying roller pair 34, and the folding unit 6 (See FIG. 1). When the bundle raising member 25 reaches the lower end of the lower unit 15, it is retracted to the back side of the intermediate tray 23 so as not to hinder the conveyance of the sheet bundle P. The bundle lowering member 32 presses the rear end until the front end of the sheet bundle P reaches the conveying roller pair 34.

  The sheet bundle P sent out by the conveying roller pair 34 is bent along the staple by the center folding unit 6, and the folded booklet sheet bundle P is discharged to the booklet tray 16 (see FIG. 1). . When the folding process is not selected, the sheet bundle P with the center binding is discharged to the discharge tray 12 or the job tray 13 in the same manner as the sheet bundle P with the front end binding. (See FIG. 1).

  Next, the lower unit 15 will be described with reference to FIGS. 3 and 4 when viewed from the back side. FIG. 3 is a perspective view of the lower unit 15 as viewed from the back side of the intermediate tray 23. FIG. 4 is an enlarged perspective view of the guide 37 portion in the lower unit 15. Note that the description of the lower unit 15 of the post-processing apparatus 1 in the present embodiment will be made in the case of preventing erroneous detection when the position of the bundle lowering member 32 is detected by the optical sensor 36.

  As shown in FIGS. 3 and 4, on the back side of the lower unit 15, the bundle detecting member 35, the optical sensor 36 for detecting the position of the bundle lowering member 32, and the shaking of the bundle lowering member 32 are prevented, and the optical sensor 36. A guide 37 is disposed to block the light.

  The bundle member detection unit 35 includes a detection member 35a, an optical sensor 35b, a support shaft 35c for supporting the detection member 35a, an elastic body 35d, and a protrusion 35e for attaching the elastic body 35d. . As shown in FIG. 4, the detection member 35a has a fan-shaped portion 35aa having one end formed in a fan shape, a rod-shaped portion 35ab formed in a rod shape at the other end, and a cylindrical shape substantially at the center of the two portions. The fan-shaped portion 35aa, the rod-shaped portion 35ab, and the shaft portion 35ac are integrally formed. The detection member 35a is rotatably supported by fitting the shaft portion 35ac to the support shaft 35c connected to the intermediate tray 23.

  3 and 4, the bundle member detection unit 35 is provided on the left side of the first belt 26 when the lower unit 15 is viewed from the back surface. Further, the fan-shaped portion 35aa of the detection member 35a is disposed so as to be positioned above the optical sensor 35b for detecting the position of the bundle raising member provided in the intermediate tray 23. On the other hand, the rod-shaped portion 35ab of the detection member 35a is disposed so as to protrude on the first belt 26 so as to be perpendicular to the rotation direction of the first belt 26.

  As described above, the optical sensor 35b is disposed so as to be sandwiched between the fan-shaped portion 35aa and the intermediate tray 23. The elastic body 35d is made of, for example, a spring, and both ends thereof are attached to the protrusion 35e and the rod-shaped portion 35ab of the detection member 35a.

  Here, the position detection of the bundle raising member 25 will be described. When the bundling member 25 comes into contact with the rod-shaped portion 35ab of the detection member 35a due to the vertical movement of the first belt 26, the rod-shaped portion 35ab of the detection member 35a is lifted or pushed down depending on the moving direction of the bundle raising member 25. It is done. Since the detection member 35a is rotatably supported at the shaft portion 35ac, the fan-shaped portion 35aa moves up and down in conjunction with the vertical movement of the rod-shaped portion 35ab. When the fan-shaped portion 35aa is rotated about the shaft portion 35ac and moved up and down, the fan-shaped portion 35aa does not exist from the detection range of the optical sensor 35b, and the light receiving state of the optical sensor 35b changes. Thereby, the optical sensor 35b detects passage of the bundle raising member 25. The detecting member 35a rotated by the bundle member 25 has an elastic body 35d so that the fan-shaped portion 35aa comes above the optical sensor 35b and the rod-shaped portion 35ab is perpendicular to the rotation direction of the first belt 26. It is returned to such a position. That is, it returns to the normal position.

  In this manner, the position of the bundle raising member 25 is detected, the predetermined position is stopped as a reference position, and the drive of the motor M1 is pulse-controlled according to conditions such as the size of the paper, whereby the bundle raising member Stack processing and stapling processing can be performed by moving 25 to an appropriate position on the intermediate surface side.

  On the other hand, on the second belt 31 provided in parallel with the first belt 26, the bundle lowering member 32 is formed in a substantially T shape, and a leg portion 32a that stands upright on the second belt 31 and the tip of the leg portion 32a. And a head portion 32b to which a substantially central portion in the longitudinal direction is coupled. The leg portion 32a is for pressing the rear end of the paper, and the head portion 32b is for restricting the rear end of the paper from falling off the leg portion 32a when pressed. The rotation shaft 30 (drive rotation shaft) around which the second belt 31 is wound is rotationally driven by the motor M2 so as to be rotatable forward and backward, whereby the bundle lowering member 32 moves.

  The bundle lowering member 32, which is a protrusion, is moved by a predetermined amount of rotation in the direction in which the second belt 31 is transported downward from the reference position to lightly press the rear end of the paper and align the rear end of the paper. Perform alignment processing. This is to prevent the rear ends of a plurality of stacked sheets from becoming uneven when the sheets are sent to the processing unit 5 and the leading ends of the sheets are received and stacked by the bundle raising member 25.

  This operation is performed every time one sheet is stacked, and the bundle lowering member 32 is returned to the original position, that is, the back side of the intermediate tray 23 every time one sheet is pressed. As a result, the trailing edges of the stacked sheets can be aligned, so that the consistency of the sheet bundle P is enhanced and the stapling process can be performed accurately. Further, if the bundle lowering member 32 is formed of an elastic member, the sheet can be pressed with an appropriate force. Therefore, it is possible to prevent the paper from being bent when pressed.

  The optical sensor 36 is a means for detecting the reference position of the bundle lowering member 32. The optical sensor 36 is provided on the right side of the second belt 31 and above the intermediate tray 23 when viewed from the back side of the lower unit 15. When the bundle lowering member 32 moves in the vertical direction and the bundle lowering member 32 enters the detection range of the sensor and the light is reflected by the leg portion 32a, the optical sensor 36 receives the light. Thereby, the position of the bundle lowering member 32 can be confirmed, and for example, the detection position of the optical sensor 36 can be determined as the reference position. Note that the reference position can be appropriately set according to the balance between the detection of the optical sensor 36 and the pulse control of the motor M2.

  In addition, when the reference position is clearly determined, there is no occurrence of insufficient pressing or excessive pressing of the sheet. That is, if the bundle lowering member 32 is stopped at the reference position by detecting the position of the optical sensor 36, and the drive of the motor M1 is pulse-controlled according to conditions such as the paper size, the bundle lowering member 32 is moved to the intermediate tray 23. The sheet alignment process of moving to an appropriate position on the front side and pressing the trailing edge of the sheet can be accurately performed with high accuracy.

  As shown by a dotted line in FIG. 4, the detection range S of the optical sensor 36 varies depending on the optical sensor 36. For example, as shown by the dotted line in FIG. A detection range S that detects up to the member 25 may be used. A guide 37 is provided behind the bundle lowering member 32 and in front of the bundle raising member 25 in the irradiation direction of the optical sensor 36. That is, the guide 37 is provided between the first belt 26 and the second belt 31.

  The guide 37 blocks light from the optical sensor 36. As shown in FIG. 4, the bundle raising member 25 has a substantially L-shaped cross section when viewed from the irradiation direction of the optical sensor 36, and is difficult to detect by the optical sensor 36, but without the guide 37, the bundle described above. The optical sensor 36 may erroneously detect the bundle raising member 25 due to the vertical movement of the raising member 25. Due to this erroneous detection, the second belt 31 provided with the bundle lowering member 32 cannot be rotationally driven accurately, leading to insufficient or excessive pressing of the paper. Thus, the guide 37 plays a role of preventing erroneous detection of the position of the bundle lowering member 32 of the optical sensor 36. Furthermore, this guide 37 eliminates the need to adjust the optical sensor 36 so that the bundling member 25 is not included in the detection range, or to use such an optical sensor 36, and makes a false detection with a simple configuration. It can be surely prevented.

  The guide 37 can use a matte black member in order to improve the light shielding property. If matte, the surface of the member is not smooth, so that light can be diffusely reflected. Here, as the member, the surface of the black resin member may be finely roughened, or a matte black paint may be applied, and further, some member such as black felt or matte black tape is used. You may stick. Thus, the guide 37 that can reliably prevent erroneous detection can be easily procured.

  As shown in FIG. 4, the guide 37 is formed on the surface adjacent to the second belt 31 so that the cross section in the rotation direction of the second belt 31 is substantially trapezoidal. If the guide 37 is formed in this way, even if the bundle lowering member 32 swings in a direction perpendicular to the rotation direction, the guide 37 does not prevent the rotation of the bundle lowering member 32 and prevents the bundle lowering member 32 from shaking. Thus, the detection of the position of the bundle lowering member 32 by the optical sensor 36 can be prevented reliably.

  In this way, the sheet discharged from the image forming apparatus 2 is received into the apparatus main body through the carry-in port 7, and the sheet is conveyed in the apparatus and subjected to predetermined processing such as stapling, and after the predetermined processing. In the post-processing apparatus 1 in which the paper is discharged to the discharge tray 12 or the job tray 13, a processing unit 5 is provided in the post-processing apparatus 1 for stacking a plurality of sheets and performing the predetermined processing. The processing unit 5 includes a protrusion provided on an endless second belt 31 that is driven to rotate forward and backward, an optical sensor 36 for detecting the position of the bundle lowering member 32 as a protrusion, and a protrusion. If a guide 37 for blocking the light of the optical sensor 36 and preventing the bundling member 32 as a protrusion from shaking is provided at a position on the back side in the irradiation direction of the optical sensor 36, the sensor Even if there is flux lowering member 32 other than the members of the projecting portion to be detected and located in the detection range, since the guide 37 to shield the light sensor, it is unnecessary to detection sensor erroneously. Furthermore, since the bundle lowering member 32 as the protrusion is prevented from shaking during the rotation of the belt by the guide 37, the sensor does not vary in detecting the position of the bundle lowering member 32 as the protrusion, and is highly accurate. Can be detected.

  If the guide 37 is a matte black member, the light of the optical sensor 36 can be reliably shielded by a simple method using a matte black material or painting the matte black on the guide 37. .

  Further, each time a sheet is stacked, the protrusion is a bundle-lowering member 32 that aligns the sheet by pressing the end of the sheet from above by forward / reverse rotation of the belt. Each time the sheets are stacked, the paper is aligned by pressing the edge of the paper from above by forward / reverse rotation of the belt. Therefore, after the position of the bundle lowering member 32 as the protrusion is accurately detected, the paper is aligned. This eliminates insufficient press and paper press.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the above-described embodiment, the case of the bundle lowering member 32 has been described as a protrusion for preventing erroneous detection. However, by appropriately selecting the shape and arrangement of the bundle raising member 26, erroneous detection of the bundle raising member 26 is prevented. Even in this case, the present invention can be applied.

  The present invention can be used in a post-processing apparatus configured to perform predetermined post-processing on a sheet or the like supplied from an image forming apparatus and discharge the paper.

It is sectional drawing seen from the front which shows schematic structure of the post-processing apparatus in embodiment of this invention. It is a schematic perspective view which shows the paper conveyance mechanism of the lower unit of the post-processing apparatus in embodiment of this invention. It is the perspective view which looked at the lower unit in the embodiment of the present invention from the back side of the intermediate tray. It is an expansion perspective view of the guide part of the lower unit in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Post-processing apparatus 25 Bundle raising member 26 1st belt 31 2nd belt 32 Bundle lowering member (projection part)
36 Optical sensor 37 Guide S Detection range

Claims (3)

The paper discharged from the image forming apparatus is received in the apparatus main body through the carry-in port, and the paper is transported in the apparatus and subjected to predetermined processing. After the predetermined processing, the paper is discharged to the tray. In the device
A processing unit for stacking a plurality of sheets and performing the predetermined processing is provided in the post-processing device,
The processing unit has a protrusion provided on an endless belt that is driven to rotate forward and backward, and
An optical sensor for detecting the position of the protrusion;
A post-processing apparatus characterized in that a guide for shielding the light of the photosensor and preventing the projection from shaking is provided at a position on the back side in the irradiation direction of the photosensor with respect to the projection. .   The post-processing apparatus according to claim 1, wherein the guide is a matte black member.   3. The protruding portion is a bundle lowering member that aligns sheets by pressing a sheet end from above by forward / reverse rotation of the belt each time a sheet is stacked. Post-processing device as described.

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