JP2012025491A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove foreign matter on a conveying belt conveying paper using air suction, thereby preventing feeding mistakes (no-feeding) due to lowering of a friction force of the conveying belt and preventing image failures due to the foreign matter.SOLUTION: A paper feeding device includes a cleaning hole different from a paper suction hole sucking paper, and sucks foreign matter on a conveying belt to remove.

Description

  The present invention relates to a paper feeding device, and more particularly to a paper feeding device mounted on an image forming apparatus that forms an image on paper such as a copying machine or a printer.

  2. Description of the Related Art Conventionally, various methods have been used in a paper feeding device of an image forming apparatus to separate and transport paper in a paper feeding tray that stores paper.

  As one of the methods, there is a method of feeding paper using frictional force between a rubber roller or a rubber belt and the paper.

  Recently, in the field of production printing and the like, in order to stably feed a large amount of sheets, a method of separating and transporting the uppermost sheet of the sheet feed tray while air is used is used.

  FIG. 1 is a diagram illustrating an example of a conventional paper feeding device using a method of conveying a belt while sucking and separating paper P by air suction. As shown in FIG. 1, a paper feed unit 320 is disposed near the front end of the paper feed direction of the paper P in the paper feed tray 310. The paper table 311 on which the paper P is stacked is moved up and down by driving means (not shown) so that the uppermost surface of the paper P has a constant height regardless of the paper stacking amount.

  The sheet feeding unit 320 includes a conveying belt 321 that rotates by winding a large roller 322 connected to a driving source and two small rollers 323. The conveying belt 321 has a large number of small-diameter through holes. A suction unit 324 is disposed inside the transport belt 321, sucks the paper P through the transport belt 321, and sucks and transports the paper P to the transport belt 321. When the transport belt 321 rotates while sucking the paper P, the uppermost paper P in the paper bundle stored in the paper feed tray 310 advances in the direction of the arrow X in the figure and is sent to the image forming unit.

  As such a paper feeding device using air suction, for example, a paper feeding device of Patent Document 1 is disclosed.

  Further, in Patent Document 2, a pulley that winds and rotates a conveyance belt that conveys a sheet and a cleaning roller that contacts a surface opposite to the sheet conveyance surface of the conveyance belt and removes paper dust and the like are provided and removed. By introducing paper dust or the like to the air duct, it has been devised to prevent scattering of paper dust or the like and to prevent a decrease in the frictional conductivity between the pulley and the conveyor belt.

JP 2009-107849 A JP-A-10-297783

  Compared with the conventional roller paper feeding device using frictional force, the paper feeding device by air adsorption is a paper based on the difference between the frictional force between the rubber roller and the paper and the frictional force between the paper and the paper in a torque limiter etc. Since no separation is performed, there is little influence of foreign matter adhering to the conveyor belt (rubber).

  However, foreign matter may adhere to the conveyor belt due to long-term use, and a feeding error (no feed) may occur due to a decrease in the frictional force of the conveyor belt (rubber). Foreign matter adhering to the rubber belt is not only paper dust and paper filler, but also the coating material components of coated paper and the dusting of reprint paper (blocking powder to prevent show-through of offset printed paper). There is.

  In order to clean them, brush pressing, scraper pressing, etc. can be considered, but if the scraped foreign matter adheres to the paper to be fed from now on, JAM or the like may be caused by erroneous detection of a defective image due to the foreign matter or foreign matter. Is likely to occur.

  In Patent Document 2, the cleaning member on the inner surface of the transport belt and the removed foreign matter are sucked with suction air, but the outer surface of the transport belt, which is the paper transport surface, cannot be sufficiently cleaned, and is scraped off because of the lower feed mechanism. There is a concern that the foreign matter may be reattached to the paper (original) to be fed again, which may cause image defects due to the foreign matter.

  The present invention has been made to solve the above-described problem, and removes foreign matters on a conveyance belt that conveys a sheet by air adsorption, and eliminates a feeding error (no feed) due to a decrease in the frictional force of the conveyance belt. An object of the present invention is to provide a paper feeding device capable of preventing image defects due to foreign matter.

  The above object is achieved by the invention described below.

1. A paper feed tray for stacking a stack of paper sheets,
Suction means for generating an air negative pressure for sucking air from the uppermost sheet of the bundle of sheets stacked on the sheet feeding tray one by one;
Conveying belt with a plurality of holes for sucking, sucking, adsorbing, rotating around a plurality of rollers, and conveying a sheet with the suction means;
A sheet suction hole for taking in air through the transport belt and sucking the paper; and a cleaning hole for taking in air and sucking in foreign matter on the transport belt, and having an air duct for guiding the flow of air by the suction means. A paper feeder characterized by.

  2. 2. The sheet feeding device according to claim 1, wherein an opening area of the cleaning hole is smaller than an opening area of the sheet suction hole.

3. An opening valve for restricting the passage of air in the cleaning hole;
The release valve is closed until the sheet is sucked into the sheet suction hole via the conveyor belt,
3. The above 1 or 2, wherein when the sheet is adsorbed in the sheet suction hole, the cleaning hole is opened by the deflection of the release valve by a suction force due to an air negative pressure in the air duct. Paper feeder.

  4). 1 to 3, wherein the cleaning hole has a belt cleaning member that is located downstream or upstream in the transport direction of the transport belt, and that contacts the transport belt and cleans foreign matter adhering to the transport belt. The sheet feeding device according to any one of the above.

  5. 5. The sheet feeding device according to 4, wherein the belt cleaning member is a fur brush.

  6). 6. The sheet feeding device according to 5, wherein the belt cleaning member is a cylindrical roller and rotates at a linear speed different from that of the conveyor belt.

  7). 4. The roller according to any one of 4 to 6, further comprising a roller that is in contact with a surface opposite to the surface of the conveyance belt with which the belt cleaning member is in contact, and nips the belt cleaning member and the conveyance belt. The sheet feeding device according to one item.

  The present invention sucks and removes foreign matters on a conveyance belt that conveys paper by air suction into a cleaning hole, prevents feeding errors (no feed) due to a decrease in frictional force of the conveyance belt, and prevents image defects due to foreign matters. Is possible.

It is a figure which shows the example of the conventional paper feeder using the method of conveying a belt, attracting | sucking and isolate | separating the paper P by air suction. 1 is an overall configuration diagram of an image forming system in which a paper feeding device is incorporated. 3 is a perspective view showing a main part of the paper feeding device 30. FIG. 2 is a schematic cross-sectional view of a paper feeding device 30. FIG. It is a figure which shows an example of the adsorption conveyance part 60 of the paper feeder which concerns on this invention. FIG. 6 is a diagram illustrating a state in which foreign matter attached to the conveyance belt 64 is taken into a cleaning hole.

  The present invention will be described based on the illustrated embodiment, but the present invention is not limited to the embodiment.

(Image forming device)
FIG. 2 shows a configuration in which a sheet feeding device according to an embodiment of the present invention is incorporated, and image formation composed of an image forming apparatus A, an image reading device SC, an automatic document feeder DF, and a large capacity sheet feeding device LT. 1 is an overall configuration diagram of a system.

  The illustrated image forming apparatus A includes an image forming unit including a photosensitive member (image carrier) 1, a charging unit 2, an image exposing unit 3, a developing unit 4, a transfer unit 5, a cleaning unit 6, and the like, a fixing unit 7 and And a paper transport system.

  The paper transport system includes a paper feed cassette 10, a first paper feed means 11, a second paper feed means 12, a paper discharge means 14, a transport path switching means 15, a circulation refeed means 16, a reverse paper discharge means 17, and the like. Has been. In addition, a control unit AS is provided as control means for controlling each part of the apparatus.

  The document d placed on the document table of the automatic document feeder DF is conveyed by the document feeding means, the image on one or both sides of the document is read by the optical system of the image reading device SC, and read by the image sensor CCD. It is. The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing and the like in the image processing unit 20 and then sent to the image exposure apparatus 3.

  In the image forming unit, processes such as charging, exposure, development, transfer, separation, and cleaning are performed.

  In the image forming unit, a charge (negative charge in the present embodiment) is applied to the photosensitive member 1 by the charging unit 2, and an electrostatic latent image is formed by laser light irradiation from the image exposure device 3. The electrostatic latent image is visualized by 4 and becomes a toner image (in this embodiment, the toner is negatively charged).

  Next, the paper P stored in the paper feed cassette 10 is conveyed from the first paper feed means 11.

  The paper P is conveyed in synchronism with the toner image by the second paper feeding means 12 composed of registration rollers. Thereafter, the paper P is fixed by the fixing device 7 after the toner image is transferred by the transfer means 5. The paper P after fixing is discharged out of the apparatus by the paper discharge means 14.

  In the case of double-sided copying, the paper P on which the image is formed on the first side is sent to the circulation refeed unit 16 and reversed, and after the image is formed again on the second side in the image forming unit, the paper discharge unit 14 is formed. Is discharged out of the apparatus. In the case of reverse paper discharge, the paper P branched from the normal paper discharge path is switched back by the reverse paper discharge means 17 and turned upside down, and then discharged from the apparatus by the paper discharge means 14.

  On the other hand, the transfer residual toner on the photosensitive member 1 is removed by the cleaning unit 6.

(Paper feeder)
The large-capacity paper feeding device LT connected to the image forming apparatus A has a plurality of paper feeding devices 30 inside, accommodates a large amount of paper P, and feeds the paper P to the image forming apparatus A one by one. To do.

  The sheet feeding device 30 includes a sheet stacking tray 31 on which a plurality of sheet bundles are stacked, a sheet leading edge regulating member 32, a sheet trailing edge regulating member 33, and a guide rail 34. In this example, the sheet stacking trays 31 are configured in three stages, and each sheet stacking tray 31 is configured to be able to be pulled out from the large capacity sheet feeding device LT by the guide rail 34. For example, the large-capacity paper feeder LT can accommodate 1300 sheets in the first tray, 1850 sheets in the second and third trays, and can accommodate approximately 5000 sheets as a whole.

  FIG. 3 is a perspective view illustrating a main part of the paper feeding device 30, and FIG. 4 is a schematic cross-sectional view of the paper feeding device 30. In FIG. 3, the suction conveyance unit 60 that is a suction conveyance unit is shown in a temporary position that is horizontally shifted by an arrow b toward the downstream side in the paper conveyance direction from the position where it is actually installed in the paper feeding device 30. ing.

  As shown in FIG. 3, the sheet bundle Ps and the uppermost sheet P are stacked on the sheet stacking tray 31 and are housed together with the sheet stacking tray 31 so as to be moved up and down by a mechanism (not shown).

  The pair of sheet side end regulating portions 80 regulates the sheet bundle Ps in the width direction orthogonal to the sheet transport direction, and has a sheet side end regulating member 81 adjacent to the side end of the sheet bundle Ps. . The sheet-side end regulating unit 80 can freely change the relative distance in the sheet width direction, and regulates the position of the sheet bundle Ps in the width direction corresponding to the sheet size.

  The sheet-side edge regulating unit 80 has a box-like structure that is sufficiently long in the sheet conveyance direction and has high rigidity and strength, and the sheet-side edge regulating member 81 and the side edge of the sheet at the uppermost part of the sheet bundle Ps. This gap can be kept below a predetermined value even for a wide range of paper sizes.

  The paper leading edge regulating member 32 regulates the leading edge of the sheet bundle Ps on the paper stacking tray 31 and is fixed to the paper feeding device 30.

  The sheet trailing edge regulating member 33 is movable in the length direction of the sheet P and regulates the position of the trailing end in the sheet conveying direction, and is supported by the sheet feeding device 30 so as to be displaceable in the sheet conveying direction. Yes. The sheet-side edge regulating member 81 and the sheet trailing edge regulating member 33 have a height and a shape that can always regulate a sheet that has been floated by blowing wind, which will be described later.

  As shown in FIG. 4, a height sensor PS <b> 3 that detects the height of the uppermost portion of the sheet bundle Ps stacked on the sheet stacking tray 31 is disposed on the sheet rear end regulating member 33.

  The uppermost position of the sheet bundle Ps stacked on the sheet stacking tray 31 is maintained at an optimum height at which air can be blown based on a signal from the height sensor PS3. That is, based on the detection result of the height sensor PS3 shown in FIG. 4, a lift motor (not shown) is driven to raise the paper stacking tray 31, so that the uppermost part of the paper bundle Ps is always maintained at a predetermined height. Is going.

  Further, on the exit side of the large-capacity paper feeding device LT, a pair of transport rollers 39 including two main and driven rollers that transport the paper P transported by the suction transport unit 60 to the image forming apparatus A is disposed. ing.

  A paper feed sensor PS <b> 2 that detects the passage of the paper P is provided between the suction conveyance unit 60 and the conveyance roller 39.

<Blower part>
The blower unit 50, which is a sheet separating unit disposed on the downstream side of the sheet stacking tray 31 in the sheet P feeding direction, will be described.

  The blower unit 50 includes an electric fan 51 and a blower guide 52 connected to the electric fan 51. The blower 50 blows air from the blower opening 53A of the blower guide 52 to the front end / upper direction (in the direction of arrow A1 in FIG. 3) of the sheet bundle Ps loaded on the paper stacking tray 31.

  The air blown from the first air outlet 53A is for rolling up and floating the uppermost sheet P of the sheet bundle Ps, and is directed to the upper front end of the sheet bundle Ps. The upper portion of the air blowing guide 52 has a second air blowing port 53B on the downstream side of the air blowing port 53A, and the second air blowing port 53B opens upward from the air blowing port 53A.

  The air blown from the second air blowing port 53B is for separating the paper P sucked and conveyed by the suction conveyance unit 60 into one sheet.

  As shown in FIG. 4, the air guide 52 is formed in a duct structure that connects the first air outlet 53 </ b> A and the electric fan 51, or connects the second air outlet 53 </ b> B and the electric fan 51. The duct is branched into a first duct 54A and a second duct 54B. A shutter 55 is provided at the branch point, and the shutter 55 enables switching of the amount of air flowing through the first duct 54A and the second duct 54B.

  In other words, the blower unit 50 of this example is used both for the purpose of separating and floating the uppermost sheet P of the sheet bundle Ps and for separating the sheet sucked and conveyed by the suction conveyance unit 60 into one sheet. However, the present invention is not limited to this, and it is only necessary to blow air (corresponding to the second air outlet) so that at least the paper sucked and transported by the suction transport unit 60 is separated into one sheet.

<Suction conveyance part>
As shown in FIG. 4, the suction conveyance unit 60 is positioned above the sheet bundle Ps stacked on the sheet stacking tray 31 and is disposed on the downstream side in the sheet conveyance direction.

  FIG. 5 is a diagram illustrating an example of the suction conveyance unit 60 of the sheet feeding device according to the present invention. 5A is a view of the suction conveyance unit 60 as viewed from the paper P side, and FIG. 5B is a cross-sectional view taken along the line CC shown in FIG. 5A. ) Is a view of the suction conveyance unit 60 as viewed toward the paper P (illustrated by an arrow D), and FIG. 5D is a cross-sectional view taken along the line EE shown in FIG.

  As shown in FIG. 5B, the suction conveyance unit 60 is disposed inside one end of an endless belt (hereinafter referred to as a conveyance belt 64) in which a large number of small-diameter through holes are formed. The first roller 61 to which a driving force is supplied by the motor M1 (see FIG. 3), the second roller 62a and the third roller 62b (mainly disposed on the inner side of the other end of the conveyor belt 64 and driven to rotate). In the example, two small-diameter rollers are used, but there may be one roller).

  As shown in FIG. 5B, the two conveyor belts 64 are stretched between the first roller 61 and the second roller 62a so as to be substantially parallel to the paper P.

  Inside the conveyor belt 64, a suction fan 66 that is a suction unit that generates air negative pressure and sucks air and an air duct 65 that guides the flow of air are arranged. Air sucked by the suction fan 66 is discharged to the side through the air duct 65.

  The air duct 65 is provided with a paper suction hole 67 (illustrated by a dotted line) and a cleaning hole 68 (illustrated by a dotted line) for taking in air through the through hole of the conveyor belt 64.

  The cleaning hole 68 is provided with an open valve 69 made of an elastic member whose one side in a direction perpendicular to the conveying direction of the conveying belt 64 is attached to the air duct 65. The release valve 69 opens and closes in the direction of taking air into the air duct 65 and functions as a function of restricting air passing through the cleaning hole 68.

  Further, a cleaning roller 70 that is in contact with the outer peripheral surface of the conveyor belt 64 and is rotated by a drive motor (not shown) is provided in the vicinity of the downstream side of the cleaning hole 68.

  The cleaning roller 70 is a cylindrical conductive fur brush roller in which conductive fibers are planted on the outer periphery of a conductive roller (core metal).

  In FIG. 5C, the cleaning hole 68 is provided upstream of the cleaning roller 70 in the transport direction of the transport belt 64, but may be provided downstream of the cleaning roller 70. Alternatively, a second cleaning hole and a second opening valve may be provided downstream of the cleaning roller 70 and function together with the cleaning hole 68 and the opening valve 69 positioned upstream of the cleaning roller 70.

  A roller 71 that faces the cleaning roller 70 and is located on the opposite surface of the conveyance belt 64 and nips the conveyance belt 64 together with the cleaning roller 70 is provided to prevent the conveyance belt from being bent by the pressing force of the cleaning roller 70. ing.

  From here, the operation of the paper feeding device for sucking and removing foreign matter on the conveyor belt according to the present invention through the cleaning hole will be described.

  FIG. 6 is a diagram illustrating a state in which foreign matter attached to the conveyance belt 64 is taken into the cleaning hole. The description will proceed with reference to FIGS. 4, 5, and 6.

  When starting to feed the uppermost sheet P of the sheet bundle Ps of the sheet stacking tray 31 of the sheet feeding device 30, the suction fan 66 is driven to decompress the internal space of the air duct 65. As a result, a flow of air sucked into the paper suction hole 67 through the through hole of the transport belt 64 is generated (arrow F in FIG. 6A).

  The sheet P is adsorbed to the conveyance belt 64 by this air flow.

  The two transport belts 64 are rotated by the rotation of the first roller 61, and the sucked paper P is transported in the arrow G direction.

  Further, while the transport belt 64 is being driven, the cleaning roller 70 rotates in the direction indicated by the arrow H, and removes foreign matters adhering to the transport belt 64.

  The rotation direction of the cleaning roller 70 may be rotated in the direction opposite to the direction of the arrow H. In this case, the cleaning roller 70 rotates at a speed different from the linear speed of the transport belt 64, thereby The polishing force in between will work greatly.

  Further, a scraper such as a fur brush or a PET material that is substantially equal to the width of the conveying belt 64 in the direction perpendicular to the conveying direction of the conveying belt 64 is used without using a mechanism that drives the cleaning roller 70 with a driving motor (not shown). It is also possible to carry out cleaning by pressing it to 64.

  Returning to the explanation of the air flow again, when the paper P is attracted to the transport belt 64, the paper suction hole 67 is closed, the inside of the air duct 65 is further decompressed, and the release valve 69 attached to the cleaning hole 68 is bent. , The flow of the arrow I in FIG. 6B is generated.

  With this air flow, the foreign matter removed by the cleaning roller 70 is sucked into the cleaning hole 68 and discharged outside through the air duct.

  Further, since the opening area of the cleaning hole 68 is smaller than the opening area of the paper suction hole 67 (about 1/10 to 1/20), the suction force of the suction fan 66 that generates a reduced pressure is not increased so much. Since the amount of air flowing into the suction hole can be secured, the release valve 69 shown in FIG. 6B may not be provided.

  In addition, a paper suction sensor (not shown) that detects that the paper P is sucked into the paper suction hole 67 is provided. Until the paper suction sensor detects the paper P, the linear speed and rotation of the conveyance belt 64 and the cleaning roller 70 are detected. The direction is the same (rotation in the direction opposite to the arrow H in FIG. 6A) to suppress the cleaning force by the cleaning roller 70, the paper suction sensor detects the paper P, and the air to the cleaning hole 68 is removed. By driving the conveying belt 64 and the cleaning roller 70 at different linear velocities after the flow has occurred, the foreign matter scraped by the cleaning roller 70 is not scattered around the cleaning roller 70 and the cleaning hole 68. It becomes possible to suck in.

  In this way, foreign matters adhering to the conveyance belt 64 that conveys the paper due to air adsorption are sucked and removed into the cleaning holes to prevent a feeding error (no feed) due to a decrease in the frictional force of the conveyance belt, and also due to foreign matters carried with the paper Image defects can be prevented.

A Image forming apparatus 30 Paper feeding device 31 Paper stacking tray 39 Conveying roller 50 Blower 51 Electric fan 52 Blower guide 53A Blower 53B Blower 54A Duct 54B Duct 55 Shutter 60 Adsorbing and conveying section 61 Roller 62a Roller 62b Roller 64 Conveying belt 65 Air duct 66 Suction fan 67 Paper suction hole 68 Cleaning hole 69 Release valve 70 Cleaning roller 71 Roller LT Large capacity paper feeder M1 Motor Ps Paper bundle 310 Paper feed tray 311 Paper base 320 Paper feed unit 321 Conveying belt 322 Large roller 323 Small roller 324 Suction means PS2 Paper feed sensor PS3 Height sensor

Claims (7)

A paper feed tray for stacking a stack of paper sheets,
Suction means for generating an air negative pressure for sucking air from the uppermost sheet of the bundle of sheets stacked on the sheet feeding tray one by one;
Conveying belt with a plurality of holes for sucking, sucking, adsorbing, rotating around a plurality of rollers, and conveying a sheet with the suction means;
A sheet suction hole for taking in air through the transport belt and sucking the paper; and a cleaning hole for taking in air and sucking in foreign matter on the transport belt, and having an air duct for guiding the flow of air by the suction means. A paper feeder characterized by.   The sheet feeding device according to claim 1, wherein an opening area of the cleaning hole is smaller than an opening area of the sheet suction hole. An opening valve for restricting the passage of air in the cleaning hole;
The release valve is closed until the sheet is sucked into the sheet suction hole via the conveyor belt,
3. The cleaning hole is opened according to claim 1, wherein when the sheet is adsorbed in the sheet suction hole, the opening valve is bent by the suction force generated by the negative air pressure in the air duct, thereby opening the cleaning hole. The paper feeder described.   4. A belt cleaning member that is located downstream or upstream in the transport direction of the transport belt with respect to the cleaning hole and has a belt cleaning member that contacts the transport belt and cleans foreign matter adhering to the transport belt. The sheet feeding device according to any one of the above.   The sheet feeding device according to claim 4, wherein the belt cleaning member is configured by a fur brush.   The sheet feeding device according to claim 5, wherein the belt cleaning member is a cylindrical roller and rotates at a linear speed different from that of the conveyor belt.   7. The roller according to claim 4, further comprising a roller that is in contact with a surface opposite to the surface of the conveyance belt with which the belt cleaning member is in contact and nips the belt cleaning member and the conveyance belt. The sheet feeding device according to item 1.

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