JP5458855B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus that separate and convey a top sheet from a sheet bundle by air suction.

  Conventionally, as a sheet conveying apparatus for feeding a recording medium such as paper (hereinafter referred to as “sheet”) mounted on an image forming apparatus such as a digital copying machine, a printer apparatus, a facsimile apparatus, and an offset printing machine, for example, An air suction type sheet conveying apparatus is known.

  An example of an air suction type sheet conveying apparatus is shown in FIGS.

  As shown in FIG. 7, in the sheet conveying apparatus 101, a sheet adsorbing / conveying unit 112 including a sheet adsorbing / conveying belt 112C is provided above the sheet storage unit 111, and is stacked on a stacking tray 111A that is a horizontal plane. A plurality of sheets (hereinafter, also referred to as “sheet bundles”) 102 A, which is the uppermost sheet in the vertical direction (hereinafter, referred to as “uppermost sheet”) 102 </ b> A, is taken sheet by sheet by the air suction unit 113. It is configured to be attracted to 112C and conveyed to a predetermined position.

  Further, a blower unit 114 is provided on the downstream side (right side in the drawing) in the sheet conveying direction, and air is blown to one end of the sheet bundle 102 to separate the sheets near the uppermost sheet 102A one by one. . On the other hand, a position detection sensor 116 is provided at an upstream end that is not affected by the air blown from the blower 114. The position detection sensor 116 includes a position detection unit (for example, a digital sensor) 116A and an upper surface position detection lever 116B.

  The stacking tray 111A is connected to the sheet lifting / lowering driving means 118 and can move up and down. The sheet bundle 102 ascends together with the stacking tray 111A, the uppermost sheet 102A comes into contact with the upper surface position detection lever 116B, and the position of the uppermost sheet 102A is detected by receiving the force by which the upper surface position detection lever 116B is pushed up. It is configured.

  A large number of suction holes (not shown) are formed on the entire surface of the sheet suction conveyance belt 112C. By the air suction from the air suction unit 113, the uppermost sheet 102A is sucked to the sheet suction conveyance belt 112C through the suction hole.

  With reference to FIG. 8, the sheet conveying operation of the sheet conveying apparatus 101 will be described.

  First, the stack raising / lowering drive unit 118 raises / lowers the stacking tray 111 </ b> A, and determines whether the position detection sensor 116 has detected the upstream end of the sheet bundle 102 in the conveyance direction of the uppermost sheet 102 </ b> A. When not detected, that is, when the uppermost sheet 102A is not in contact with the upper surface position detection lever 116B, the sheet raising / lowering driving means 118 further raises the stacking tray 111A, and the uppermost sheet 102A comes into contact with the upper surface position detection lever 116B. In this case, the sheet lifting / lowering driving means 118 stops the stacking tray 111A.

  Next, air is blown to the sheet bundle 102 by the blower unit 114, and adjacent sheets including the uppermost sheet 102A are separated one by one. The floated uppermost sheet 102A is adsorbed to the sheet adsorbing and conveying belt 112C by air suction from the air sucking unit 113, and the adsorbing uppermost sheet 102A is rotated by the driving device 117, thereby causing the adsorbed uppermost sheet 102A to be predetermined. To the position. By repeating this operation in accordance with the sheet feeding timing, the sheets are continuously conveyed one after another to a predetermined position.

  In such an air suction type sheet conveying apparatus 101, if the sheet adsorbing and conveying belt 112C continues to rotate after conveying the uppermost sheet 102A, the sheet cannot be conveyed at the target timing. After the sheet is conveyed by the conveyance belt 112C, it is necessary to stop the rotation of the sheet adsorption conveyance belt 112C.

  Therefore, in the sheet conveying apparatus 101, in order to enable the sheet conveyance even when the rotation of the sheet adsorption conveyance belt 112C is stopped, the sheet adsorption device belt 112C is on the near side of a predetermined position where the uppermost sheet 102A is conveyed. By separately providing a sheet conveying means (not shown) consisting of a pair of rollers (not shown in the sheet conveying direction) and stopping the sheet adsorption conveying belt 112C, the sheet is pulled by the separately provided sheet conveying means, so that the sheet can be obtained at a target timing. Can be transported.

  In addition, as an air suction type sheet transport device, when continuously transporting a plurality of sheets, the suction is continued to the last sheet without stopping suction for each sheet, and one sheet is transported. Each time the sheet suction conveyance belt is stopped, the first conveyed sheet is conveyed by a predetermined amount by the conveyance roller pair, and then the conveyance of the next sheet is started again by the sheet adsorption conveyance belt, and the conveyance belt is immediately conveyed by the brake mechanism. There is known a technique that can stop the operation (for example, see Patent Document 1). With the technique of Patent Document 1, even if the sheet interval is reduced, it is possible to realize high speed without causing double feeding in which the previous sheet and the next sheet are overlapped and conveyed.

  However, in the conventional technology shown in FIGS. 7 and 8, since air is sucked from the suction holes on the surface of the sheet suction conveyance belt 112C even after the sheet suction conveyance belt 112C is stopped, the sheet is attracted to the sheet suction conveyance belt 112C. In the attracted state, the sheet is pulled by the separately provided sheet conveying means, and friction is generated between the surface of the sheet adsorption conveying belt 112C and the sheet, and the sheet is damaged or the sheet adsorption conveying belt 112C. There was a problem of wear.

  Further, the technique described in Patent Document 1 also has a problem that the sheet suction conveyance belt 112C is worn for the same reason as described above.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet conveying apparatus and an image forming apparatus that can reduce wear of a sheet suction conveying belt.

  The sheet conveying apparatus according to the present invention includes a sheet storage unit that stacks and stores a sheet bundle on a stacking tray, a sheet elevating unit that elevates and lowers the sheet bundle stacked on the stacking tray, and the sheet elevating unit. An air blowing unit that blows air from the downstream side in the sheet conveyance direction to the sheet bundle raised by the above, floats the upper sheet including at least the uppermost sheet of the sheet bundle, and separates the sheets, and sheet adsorption A suction belt formed on a surface of the transport belt and the sheet suction transport belt, and sucking air from the air suction hole to suck the uppermost sheet onto the sheet suction transport belt, and A sheet adsorbing and conveying means for conveying the uppermost sheet by rotating a conveying belt; and a sheet of the sheet adsorbing and conveying means A downstream sheet conveying unit that is further provided on the downstream side in the feeding direction and further conveys the uppermost sheet conveyed by the sheet adsorbing and conveying unit; the sheet adsorbing and conveying unit; and a control unit that controls the downstream sheet conveying unit The sheet adsorbing and conveying belt is divided into a low friction portion having a low friction coefficient and a high friction portion having a high friction coefficient in the rotation direction of the sheet adsorbing and conveying belt, and the control means In the state where the high friction portion faces the uppermost sheet, sucks air from the air suction hole and starts rotation of the sheet adsorbing and conveying belt, and the uppermost sheet reaches the downstream sheet conveying means. At the same time, the rotation of the sheet adsorbing / conveying belt is stopped at the position where the low friction portion contacts the uppermost sheet, and the air suction hole And the downstream sheet conveying means is controlled to convey the uppermost sheet, and when the uppermost sheet reaches the downstream sheet conveying means, the low friction portion is moved to the uppermost sheet. The length of the low friction portion, the length of the high friction portion, and the distance between the sheet suction conveyance belt and the downstream sheet conveyance means are set so as to contact the sheet.

  With this configuration, when the uppermost sheet is pulled downstream in the conveying direction by the downstream sheet conveying means while the uppermost sheet is in contact with the low friction part, the uppermost sheet is brought into contact with the low friction part of the sheet adsorption conveying belt. The contact between the uppermost sheet and the sheet adsorbing / conveying belt reduces the friction between the uppermost sheet and the sheet adsorbing / conveying belt. It can be limited to.

  Therefore, it is possible to reduce the wear of the sheet adsorption conveyance belt.

  In the sheet conveying apparatus according to the present invention, the surface state of the sheet adsorption / conveying belt is different between the low friction part and the high friction part.

  With this configuration, the surface state can be made different while the low friction portion and the high friction portion are configured using the same material, and the manufacturing cost can be reduced.

  An image forming apparatus according to the present invention includes the sheet conveying device.

  With this configuration, it is possible to reduce wear of the sheet suction conveyance belt in the image forming apparatus including the sheet conveyance device.

  ADVANTAGE OF THE INVENTION According to this invention, the sheet | seat conveying apparatus and image forming apparatus which can reduce abrasion of a sheet | seat adsorption | suction conveyance belt can be provided.

1 is a schematic configuration diagram of an image forming apparatus including a sheet conveying device according to an embodiment of the present invention. It is sectional drawing of the sheet conveying apparatus which concerns on one embodiment of this invention. FIG. 6 is a cross-sectional view illustrating a sheet conveying operation of a sheet conveying apparatus according to an embodiment of the present invention. It is sectional drawing from the arrow Z direction of FIG. 3 of the sheet conveying apparatus which concerns on one embodiment of this invention. It is a block diagram which shows the control means of the sheet conveying apparatus which concerns on one embodiment of this invention. 2A and 2B are enlarged cross-sectional views illustrating a sheet conveying operation of a sheet conveying apparatus according to an embodiment of the present invention, in which FIG. 1A is a state at the start of rotation of a sheet adsorption conveying belt, and FIG. This is the state when the rotation of the conveyor belt is stopped. It is a schematic sectional drawing which shows an example of the conventional sheet conveying apparatus. It is a figure explaining operation | movement of the sheet conveying apparatus of FIG.

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

  First, the configuration will be described.

  As shown in FIG. 1, the image forming apparatus 51 is configured as an electrophotographic digital copier, and includes an original reading unit 52 that reads an original and an uppermost sheet (recording paper) conveyed from the sheet conveying apparatus 1. An image forming unit 53 that forms an image read by the document reading unit 52 with respect to 2A, and a sheet conveying apparatus 1 that separates one uppermost sheet 2A from the sheet bundle 2 and conveys the image to the image forming unit 53. Yes.

  The uppermost sheet 2A conveyed by the sheet conveying device 1 is conveyed by a conveying roller pair 58, and the toner image formed by the image forming unit 53 is transferred by the transfer device 59. The toner image is thermally transferred by the fixing device 60. The paper discharge roller pair 61 discharges the paper to the paper discharge tray 62.

  Hereinafter, the details of the sheet conveying apparatus 1 will be described with reference to FIGS.

  2 to 4, the sheet conveying apparatus 1 includes a sheet storage unit 11, a sheet suction conveying unit 12, an air suction unit 13, an air blowing unit 14, a driving unit 17, and a sheet lifting / lowering unit 18. And. Further, as shown in FIG. 5, the sheet conveying apparatus 1 includes a control unit 19 that controls an air suction unit 13, an air blowing unit 14, a driving unit 17, and a sheet lifting / lowering unit 18.

  The sheet storage unit 11 includes a stacking tray 11A that is a horizontal plane, and stores a plurality of sheet bundles 2 stacked on the stacking tray 11A. The sheet storage unit 11 is connected to a sheet lifting / lowering unit 18 connected to the control unit 19, and when the sheet lifting / lowering unit 18 is driven, the stacking tray 11 </ b> A moves up and down, and the sheet bundle 2 in the sheet storage unit 11. Is configured to be able to move up and down. The sheet elevating means 18 includes a stepping motor and a servo motor with an encoder so that the stacking tray 11A can be raised by an arbitrary amount.

  The sheet suction conveyance unit 12 is drivingly connected to a drive unit 17 connected to the control unit 19, and includes a sheet suction conveyance belt 12C that spans two rollers 12A and 12B. As shown in FIG. 4, a large number of suction holes 12 </ b> D are formed in the entire sheet suction conveyance belt 12 </ b> C, and air is sucked from the suction holes 12 </ b> D into the inner space of the sheet suction conveyance belt 12 </ b> C. An air suction part 13 is provided.

  As shown in FIG. 6, the sheet suction conveyance belt 12 </ b> C is divided into low friction portions 32 and 34 having a low friction coefficient and high friction portions 31 and 33 having a high friction coefficient in the rotation direction. The low friction portions 32 and 34 and the high friction portions 31 and 33 have different surface states. On the downstream side of the sheet suction conveyance unit 12 in the sheet conveyance direction, a downstream sheet conveyance unit 21 that further conveys the uppermost sheet 2A conveyed by the sheet adsorption conveyance unit 12 is provided.

  The air suction unit 13 is connected to the control unit 19, and by sucking air under the control of the control unit 19, the air suction unit 13 includes the sheet bundle 2 stacked in the sheet storage unit 11 as illustrated in FIGS. 3 and 4. The uppermost sheet 2A positioned at the uppermost part in the vertical direction is adsorbed and separated one by one on the sheet adsorbing / conveying belt 12C, and the drive unit 17 is controlled by the control means 19 with the uppermost sheet 2A adsorbed. The uppermost sheet 2 </ b> A is transported from the sheet transport apparatus 1 to the inside of the image forming apparatus 51 by being driven to rotate the sheet adsorption transport belt 12 </ b> C.

  The sheet bundle 2 is defined by a pair of sides composed of a first side 2B and a second side 2C, and a pair of sides composed of a third side 2D and a fourth side 2E (FIG. 4). It has a rectangular shape. The third side 2D and the fourth side 2E are arranged so as to be in the direction connecting the two rollers 12A and 12B of the sheet suction conveyance unit 12, respectively. The first side 2B is the right end in FIG. The second side 2C is located on the downstream side in the sheet conveying direction at the left end in FIG.

  As shown in FIG. 3, the air blowing unit 14 is provided at a position in the vicinity of the first side 2 </ b> B of the uppermost sheet 2 </ b> A and facing the first side 2 </ b> B, and is connected to the control means 19. ing. The air blower 14 floats the uppermost sheet 2A and the sheet in the vicinity of the first side 2B of the uppermost sheet 2A by blowing air to the sheet bundle 2, and a plurality of sheets including the uppermost sheet 2A. Are separated from each other.

  In the present embodiment, the air blowing unit 14 is disposed only at a position facing the first side 2B. However, the air blowing unit 14 is opposed to the third side 2D and the fourth side 2E. You may arrange in a position. Further, the control means 19 is connected to the uppermost sheet position detection means (not shown) for detecting the vertical position of the uppermost sheet 2A of the sheet bundle 2, and the control means is based on the vertical position of the uppermost sheet 2A. 19 controls the sheet elevating means 18 so that the sheet bundle 2 rises to the vertical position optimal for the suction of the uppermost sheet 2A by the air suction unit 13, and controls the drive unit 17 that rotates the sheet suction conveyance belt 12C. It is supposed to be.

  The operation of the sheet conveying apparatus 1 configured as described above will be described.

  In the sheet conveying apparatus 1, as shown in FIG. 6A, the control unit 19 sucks air from the suction hole 12D in a state where the high friction portion 31 faces the uppermost sheet 2A, and the sheet adsorption conveying belt 12C. Start rotating. In FIG. 6A, the sucked sheet is already in contact with the sheet suction conveyance belt 12C.

  Next, as shown in FIG. 6 (b), the control means 19 sets the sheet adsorbing and conveying belt at a position where the uppermost sheet 2A reaches the downstream sheet conveying means 21 and the low friction part 34 contacts the uppermost sheet 2A. Stop the rotation of 12C. That is, the sheet suction conveyance belt 12C is stopped at the same position (position where the low friction portion 34 or the low friction portion 32 is in contact with the uppermost sheet 2A) for each sheet conveyance.

  Next, the control means 19 continues to suck air from the suction holes 12D and conveys the uppermost sheet 2A by the downstream sheet conveying means 21.

  When the next sheet is sucked and conveyed, the sheet is conveyed by the high friction unit 33, and the sheet adsorption conveyance belt 12C is stopped in a state where the low friction unit 32 is in contact with the next sheet.

  2A, the uppermost sheet 2A is pulled downstream in the conveying direction by the downstream sheet conveying means 21 in a state where the uppermost sheet 2A is in contact with the low friction portion 34. Sometimes, the uppermost sheet 2A is in contact with the low friction portion 34 of the sheet adsorption / conveyance belt 12C, so that the friction between the uppermost sheet 2A and the sheet adsorption / conveyance belt 12C is reduced, and the uppermost sheet 2A is caused by friction. Can be prevented, and the wear of the sheet adsorbing / conveying belt 12 </ b> C can be reduced, and the wear portion can be limited to the low friction portions 32 and 34. Strictly speaking, the low-friction portions 32 and 34 of the sheet adsorption conveyance belt 12C have a little friction with the uppermost sheet 2A, but wear slightly less than when the low friction is not achieved, but wear. Since the location is limited to the low friction portions 32 and 34 and the high friction portions 31 and 33 are not worn, even if the low friction portions 32 and 34 are worn, the conveyance of the uppermost sheet 2A is not affected.

  The stop position of the sheet suction conveyance belt 12C is controlled, for example, by making a hole for position detection in the sheet suction conveyance belt 12C and detecting the hole with a position detection sensor.

  Further, the length of the low friction portions 32 and 34, the length of the high friction portions 31 and 33, and the distance between the sheet suction conveyance belt 12C and the downstream sheet conveyance means 21 are determined so that the uppermost sheet 2A has the downstream sheet conveyance means. Each of the low friction portions 32 and 34 is set so as to come into contact with the uppermost sheet 2A when reaching 21.

  Further, the image forming apparatus 51 is not limited to an electrophotographic digital copier, and may be another type of digital copier such as an ink jet system. Further, the image forming apparatus 51 is not limited to a digital copying machine, and may be configured as a printer apparatus, a facsimile apparatus, or an offset printing machine.

  As described above, in the sheet conveying apparatus 1 according to the present embodiment, the sheet suction conveying belt 12C includes the low friction portions 32 and 34 having a low friction coefficient and the high friction portions 31 and 33 having a high friction coefficient in the rotation direction. The control means 19 sucks air from the suction hole 12D while the high friction portion 31 faces the uppermost sheet 2A and starts rotation of the sheet suction conveyance belt 12C, so that the uppermost sheet 2A is on the downstream side. At the position where the low friction portion 34 comes into contact with the uppermost sheet 2A while reaching the sheet conveying means 21, the rotation of the sheet suction conveying belt 12C is stopped, the air suction from the suction hole 12D is continued, and the downstream sheet conveying means 21, the uppermost sheet 2 </ b> A is controlled to be conveyed, and when the uppermost sheet 2 </ b> A reaches the downstream sheet conveying means 21, the low friction portion 34 is The length of the low friction portions 32 and 34, the length of the high friction portions 31 and 33, and the distance between the sheet suction conveyance belt 12C and the downstream sheet conveyance means 21 are set so as to contact the upper sheet 2A. And

  With this configuration, when the uppermost sheet 2A is pulled downstream in the conveying direction by the downstream sheet conveying unit 21 in a state where the uppermost sheet 2A is in contact with the low friction portion 34, the uppermost sheet 2A is moved to the sheet adsorption conveying belt. 12C, the friction between the uppermost sheet 2A and the sheet adsorbing / conveying belt 12C is reduced, damage to the uppermost sheet 2A due to friction can be prevented, and the sheet adsorbing / conveying belt 12C. Thus, the wear portion can be limited to the low friction portions 32 and 34.

  Therefore, it is possible to reduce the wear of the sheet adsorption conveyance belt 12C.

  Further, the sheet conveying apparatus 1 according to the present embodiment is characterized in that the surface state of the sheet suction conveying belt 12C is different between the low friction portions 32 and 34 and the high friction portions 31 and 33.

  With this configuration, the surface states can be made different while the low friction portions 32 and 34 and the high friction portions 31 and 33 are configured using the same material, and the manufacturing cost can be reduced.

  The image forming apparatus 51 according to the present embodiment includes the sheet conveying apparatus 1 described above.

  With this configuration, in the image forming apparatus 51 including the sheet conveying apparatus 1, it is possible to reduce the wear of the sheet suction conveying belt 12C.

  As described above, the sheet conveying apparatus and the image forming apparatus according to the present invention have an effect of reducing the wear of the sheet adsorption conveying belt, and separate the uppermost sheet from the sheet bundle by air suction. It is useful as a sheet conveying apparatus for conveying and an image forming apparatus provided with the sheet conveying apparatus.

DESCRIPTION OF SYMBOLS 1 Sheet conveying apparatus 2 Sheet bundle 2A Uppermost sheet 11 Sheet storage part 11A Stacking tray 12 Sheet adsorption conveyance means 12A, 12B Roller 12C Sheet adsorption conveyance belt 12D Suction hole 13 Air suction part 14 Air blowing part 17 Drive part 18 Sheet raising / lowering means 19 Control means 21 Downstream sheet conveying means 51 Image forming apparatus

Japanese Patent Laid-Open No. 10-279101

Claims (3)

A sheet storage unit for stacking and storing sheet bundles on a stacking tray;
Sheet elevating means for elevating and lowering a bundle of sheets stacked on the stacking tray in a vertical direction;
An air blowing unit that blows air from the downstream side in the sheet conveying direction with respect to the sheet bundle raised by the sheet elevating unit, and floats the upper sheet including at least the uppermost sheet of the sheet bundle to separate the sheets. When,
A sheet suction conveyance belt and an air suction hole formed on the surface of the sheet suction conveyance belt, and sucking the uppermost sheet to the sheet adsorption conveyance belt by sucking air from the air suction hole; Sheet adsorbing and conveying means for conveying the uppermost sheet by rotating a sheet adsorbing and conveying belt;
A downstream sheet conveying means provided on the downstream side of the sheet adsorption conveying means in the sheet conveying direction, further conveying the uppermost sheet conveyed by the sheet adsorption conveying means;
A sheet conveying apparatus comprising: the sheet suction conveying means; and a control means for controlling the downstream sheet conveying means,
The sheet suction conveyance belt is divided into a low friction portion having a low friction coefficient and a high friction portion having a high friction coefficient in the rotation direction of the sheet suction conveyance belt,
The control means includes
While sucking air from the air suction hole in a state where the high friction portion faces the uppermost sheet and starting rotation of the sheet suction conveyance belt, the uppermost sheet reaches the downstream sheet conveyance means The rotation of the sheet adsorbing and conveying belt is stopped at a position where the low friction portion contacts the uppermost sheet, and air suction from the air suction hole is continued and the uppermost sheet is moved by the downstream sheet conveying means. Control to transport,
The length of the low friction part, the length of the high friction part, and the sheet adsorption so that the low friction part contacts the top sheet when the uppermost sheet reaches the downstream sheet conveying means. A sheet conveying apparatus characterized in that a distance between a conveying belt and the downstream sheet conveying means is set.   The sheet conveying apparatus according to claim 1, wherein a surface state of the sheet adsorption conveyance belt is different between the low friction portion and the high friction portion.   An image forming apparatus comprising the sheet conveying device according to claim 1.

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