JP5915277B2 - Paper feeding device and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding device of an image forming apparatus, and more particularly to a sheet feeding device of an image forming apparatus including a printing apparatus such as a stencil printing apparatus that performs printing by pressing a sheet against a plate cylinder on which a master is wound.

  Conventionally, in the case of paper feeding from a paper feeding unit in an image forming apparatus such as a copying machine, the paper feeding roller abuts the leading edge of the paper fed from the paper feeding tray against the nip part of a pair of registration rollers to cause a predetermined deflection. After the formation, the registration roller pair is rotationally driven by the registration driving means, and the sheet is conveyed to the image forming unit by the conveyance force of only the registration roller pair.

  In the conventional paper feeding from the paper feeding unit, the paper is conveyed to the image forming unit by the conveying force of only the registration roller pair regardless of the paper feeding from any paper feeding tray. When applied to a paper device, the speed of paper conveyance accompanying the increase in printing speed unique to the printing device, the increase in paper size and paper type used, or changes in the environment, etc. The transport load changes greatly, causing variations in the amount of paper transported by the registration roller pair, causing the image position to be shifted, limiting the types of paper that can be transported, or not being able to keep up with the speed of paper transport, and as a result However, there was a problem that the paper conveyance speed had to be reduced.

Further, even when the paper feed roller is operated with respect to the pair of registration rollers, the operation time corresponding to the small size paper (A5, B5, etc.) in the conveyance length of the paper is large when conveying the large size paper (B4, A3, etc.). Before reaching the image forming unit, the load of the paper feeding unit is applied to the registration roller pair and registration shift occurs, and the operation time according to the large size paper becomes the operation time longer than the paper length when transporting the small size paper , The second sheet is also fed, and there is a problem that registration misalignment occurs due to sheet feeding jam and sheet feeding start position deviation.

  The present invention solves the above-mentioned problems, and does not increase the size of the registration driving means, and can cope with an increase in paper conveyance speed and an increase in the number of types of paper in any paper feeding unit. In order to prevent the paper formed on the upstream side of the registration roller pair in the paper feeding direction from being bent and to prevent the paper from being bent due to excessive bending, An object of the present invention is to provide a paper feeding device capable of controlling the speed.

According to the first aspect of the present invention, there is provided a paper feed roller that is rotationally driven and a separation roller that is rotationally driven in synchronism with the paper feed roller, and forms the paper while forming the paper flexure. A sheet feeding device capable of changing a sheet feeding driving time for separating and feeding one by one toward a pair, having sheet size detecting means for detecting the sheet size in the sheet feeding direction, and the sheet detected by the sheet size detecting means When the size exceeds a predetermined value, the driving time of the separation roller during driving of the registration roller pair is increased, and the predetermined value is a distance between the registration roller pair and the paper feed roller. And

  According to the present invention, without increasing the size of the registration driving unit, the pair of registration rollers can feed out the paper in response to the increase in the speed of paper conveyance and the increase in paper types in any paper feeding unit. The paper feed speed of the paper feed roller and the separation roller is set so that the paper formed on the upstream side in the paper feed direction of the registration roller pair does not bend and the paper is not bent due to excessive deflection. A controllable paper feeder can be provided.

1 is a schematic view of an image forming apparatus to which an embodiment of the present invention can be applied. 1 is a schematic view of a paper feeding device showing an embodiment of the present invention. 1 is a schematic view of a paper feeding device showing an embodiment of the present invention. It is a block diagram of the control means used for one Embodiment of this invention.

  FIG. 1 shows a stencil printing apparatus as an image forming apparatus employing an embodiment of the present invention. In FIG. 1, a stencil printing apparatus 1 includes a printing unit 2, a plate making unit 3, a paper feeding unit 4, a plate discharging unit 5, a paper discharging unit 6, an image reading unit 7, and the like.

  The printing unit 2 disposed almost at the center of the apparatus main body 8 includes a plate cylinder 9 and a press roller 10. A plate cylinder 9 having an opening portion and a non-opening portion is configured to be detachable from the apparatus main body 8, and is rotationally driven in a clockwise direction in FIG. 1 by a plate cylinder driving means (not shown).

  Inside the plate cylinder 9, there are a support shaft 11 that also serves as an ink supply pipe, an ink roller 12 that is disposed close to the inner peripheral surface of the plate cylinder 9, and a peripheral surface of the ink roller 12. An ink supply unit 14 having a doctor roller 13 and the like whose peripheral surfaces are arranged close to each other is disposed. The ink supplied from the support shaft 11 forms an ink reservoir 15 in the vicinity of the ink roller 12 and the doctor roller 13, and the ink in the ink reservoir 15 passes through the proximity of the ink roller 12 and the doctor roller 13. The ink roller 12 is supplied in layers on the peripheral surface. The ink supplied to the peripheral surface of the ink roller 12 is brought into contact with the inner peripheral surface of the plate cylinder 9 and the ink roller 12 when the outer peripheral surface of the plate cylinder 9 is pressed by a press roller 10 which will be described later. 9 is supplied to the inner peripheral surface of the plate 9 and oozes out from the opening portion of the plate cylinder 9 and is transferred onto the sheet.

  A clamper 16 is disposed on the outer peripheral surface of the plate cylinder 9 to clamp the leading end of the master so as to wind the master on the outer peripheral surface of the plate cylinder. The clamper 16 is attached to a non-opening portion of the plate cylinder 9 so as to be freely opened and closed. When the plate cylinder 9 occupies a predetermined open position or closed position, the clamper 16 is opened and closed by an opening / closing means (not shown).

  Below the plate cylinder 9, there is disposed a press roller 10 in which both ends of the support shaft are rotatably supported by a pair of arm members 10a. The press roller 10 has a predetermined pressure contact force between the spaced position separated from the outer peripheral surface of the plate cylinder 9 and the outer peripheral surface of the plate cylinder 9 as shown in FIG. It selectively occupies the press-contact position to press-contact with.

A plate making unit 3 is disposed in the upper right part of the apparatus main body 8. The plate making unit 3 includes a master holding member 17, a platen roller 18, a thermal head 19, a master cutting means 20, master transport roller pairs 21 and 22, and the like.
The master holding member 17 is attached to a side plate (not shown) of the plate making unit 3 and rotates a core portion of a master roll 23a in which a master 23 formed by laminating a thermoplastic resin film and a porous support is wound into a roll shape. Support freely and detachable.

  A platen roller 18 disposed on the left side of the master holding member 17 is rotatably supported on a side plate (not shown) of the plate making unit 3 and is rotated by a stepping motor 24. A thermal head 19 having a large number of heating elements located below the platen roller 18 is supported by a side plate (not shown), and the surface of the heating element is pressed against the peripheral surface of the platen roller 18 by a biasing force of a biasing means (not shown). ing. The thermal head 19 selectively heats each heating element while making contact with the surface of the thermoplastic resin film of the master 23 to punch the master 23.

Master cutting means 20 is disposed on the left side of the platen roller 18 and the thermal head 19. The master cutting means 20 having a fixed blade fixed to a side plate (not shown) and a movable blade supported movably with respect to the fixed blade is such that the movable blade rotates or moves up and down with respect to the fixed blade. To cut the master 23.
On the left side of the master cutting unit 20, a pair of master transport rollers 21 and 22 is disposed. Each roller pair 21, 22 has a driving roller rotatably supported on a side plate (not shown) and a driven roller pressed against the driving roller, and each driving roller is driven to rotate by a driving means (not shown). Thus, each driven roller is driven to rotate.

  A sheet feeding unit 4 as a sheet feeding device is disposed below the plate making unit 3. The sheet feeding unit 4 includes a sheet feeding tray 26, a sheet feeding roller 27, a separation roller 28, a separation pad 28a, a registration roller pair 29, a bank sheet feeding device 25, and the like.

  A sheet feeding tray 26 on which a large number of sheets P can be stacked on the upper surface is supported by the apparatus main body 8 so as to be movable up and down, and is moved up and down by a lifting means (not shown). A pair of side fences 30 for aligning the width direction of the sheets P are disposed on the upper surface of the sheet feed tray 26, and each side fence 30 is synchronized with each other toward the sheet width direction orthogonal to the sheet conveyance direction. It is configured to be movable. A plurality of paper size detection sensors 50 serving as paper size detection means for detecting the length of the paper P in the paper feeding direction are disposed below the paper placement surface of the paper feed tray 26. The detection result by the paper size detection sensor 50 is sent to the control means 48 described later.

  Above the left end of the paper feed tray 26, a paper feed roller 27 having a high friction resistance member on the surface is disposed. The paper feed roller 27 is rotatably supported by a bracket (not shown) that is swingably supported by the apparatus main body 8. When the paper feed tray 26 is raised, the uppermost position on the paper feed tray 26 with a predetermined pressure contact force. The sheet P. The paper feed roller 27 is driven to rotate by a paper feed motor 31.

  A separation roller 28 and a separation pad 28 a are disposed on the left side of the paper feed roller 27. Each of the separation roller 28 and the separation pad 28a has a high friction resistance member on the surface thereof, and the separation roller 28 is rotationally driven in the same direction in synchronization with the rotation of the paper feed roller 27 by the paper feed motor 31. Thus, the paper P is separated and fed. The drive of the paper feed motor 31 is controlled by a control unit 48 described later.

  A registration roller pair 29 having a driving roller and a driven roller is disposed on the left side of the separation roller 28. Each roller is rotatably supported between side plates (not shown) of the apparatus main body 8, and a rotational driving force from a plate cylinder driving unit (not shown) is transmitted via a driving force transmission unit (not shown), thereby the plate cylinder 9. It is driven to rotate in synchronization with Between the separation roller 28 and the registration roller pair 29, a paper leading edge detection sensor 49 that detects the leading edge of the paper P is disposed.

  A bank paper feeding device 25 is disposed below the device body 8. The bank paper feeder 25 includes a paper feed tray 51 similar to the paper feed tray 26, a paper feed roller 52 similar to the paper feed roller 27, a separation roller pair 53 similar to the separation roller 28 and the separation pad 28a, and a transport roller pair 54. , Etc., a pair of conveying rollers 56 provided in the apparatus main body 8, a paper leading edge detection sensor 57, and the like. The bank sheet feeder main body 55 is optionally mounted below the apparatus main body 8.

A plate removal portion 5 is disposed at the upper left portion of the apparatus body 8. The plate removal unit 5 includes an upper plate removal member 32, a lower plate removal member 33, a plate removal box 34, a compression plate 35, and the like.
Both the upper plate removal member 32 and the lower plate removal member 33 have a drive roller, a driven roller, an endless belt, and the like, and the endless belt moves when the drive roller is rotationally driven by a plate discharge drive means (not shown). Further, the lower plate discharge member 33 is configured to be movable by a moving means (not shown), and selectively occupies an initial position shown in the figure and a peeling position where the endless belt contacts the outer peripheral surface of the plate cylinder 9.

  The plate removal box 34 for storing the used master therein is configured to be detachable from the apparatus main body 8. A compression plate 35 for pushing the used master carried by the upper plate removal member 32 and the lower plate removal member 33 into the plate release box 34 is supported by the apparatus main body 8 so as to be movable up and down, and is moved up and down by a lifting means (not shown). The

A paper discharge unit 6 is disposed below the plate discharge unit 5. The paper discharge unit 6 includes a peeling claw 36, a paper transport unit 37, a paper discharge tray 38, and the like.
The base end of the peeling claw 36 is swingably supported by the apparatus main body 8, and the free end formed in an acute angle is swung by a claw swinging means (not shown) so that the outer periphery of the plate cylinder 9 is It selectively occupies a position close to the surface and a spaced position separated from the outer peripheral surface of the plate cylinder 9 in order to avoid obstacles such as the clamper 16.

  The sheet conveying means 37 disposed on the lower left side of the peeling claw 36 includes a driving roller, a driven roller, an endless belt, a suction fan, and the like. The driving roller is driven to rotate and sucked by a paper discharge driving means (not shown). By operating the fan, the sheet P is sucked onto the endless belt and conveyed leftward.

  A paper discharge tray 38 is disposed on the left side of the paper transport unit 37. A paper discharge tray 38 on which a large number of printed sheets P conveyed by the sheet conveying means 37 are stacked has one end fence 39 and a pair of side fences 40 for aligning the sheets P on the upper surface thereof. ing. The end fence 39 is movable in the same direction as the paper conveyance direction, and each side fence 40 is configured to be able to contact and separate from each other in the same direction as the paper width direction.

  An image reading unit 7 is disposed on the upper part of the apparatus main body 8. The image reading unit 7 includes a contact glass 41 on which a document is placed, a pressure plate 42 that can be moved toward and away from the contact glass 41, a scanning unit 43 that scans and reads a document image, a lens 44 that focuses the scanned image, and a focus. And an image sensor 45 such as a CCD for processing the image. Above the pressure plate 42, an ADF unit 46 used for continuously reading a document is disposed.

Based on the above configuration, the operation of the stencil printing apparatus 1 will be described below.
After an original to be printed is placed on the contact glass 41 by the operator, when a plate making start key (not shown) is pressed with the pressure plate 42 closed, an original image reading operation is performed in the image reading unit 7. . The image is read by scanning the document image with the scanning unit 43, and the read image is focused by the lens 44 and then sent to the image sensor 45.

  In parallel with the image reading operation, the plate discharging unit 5 performs a plate discharging operation for peeling the used master from the outer peripheral surface of the plate cylinder 9. When a plate making start key (not shown) is pressed, a plate cylinder driving means (not shown) is actuated to start the rotation of the plate cylinder 9, and the rotation stops when the plate cylinder 9 reaches a predetermined discharging position. Then, the lower plate removal member 33 operates and moves to the peeling position, and the used master on the plate cylinder 9 is scooped up by the lower plate removal member 33. Thereafter, the plate cylinder 9 is rotationally driven and the upper plate discharging member 32 is operated, and the used master on the plate cylinder 9 is conveyed by the plate discharging members 32 and 33 and stored in the plate discharging box 34. Thereafter, the compression plate 35 is actuated to compress the used master in the discharge plate box 34 and the plate cylinder 9 is rotated to a predetermined plate feeding position and stopped, the clamper 16 is opened, and the stencil printing apparatus 1 is fed. It becomes a plate standby state.

  In parallel with the plate removal operation, the plate making unit 3 performs the plate making operation. When a plate making start key (not shown) is pressed, the platen roller 18 and each of the master transport roller pairs 21 and 22 rotate, and the master 23 is pulled out from the master roll 23a. The drawn master 23 is punched when passing through the thermal head 19, and a plate-making image is formed on the surface of the thermoplastic resin film. When the leading end of the master 23 is conveyed to a position where it can be held by the clamper 16, the clamper 16 is closed, and the master 23 that has been subjected to plate making is held on the outer peripheral surface of the plate cylinder 9. Thereafter, the plate cylinder 9 rotates at the same peripheral speed as the conveying speed of the master 23, and the winding operation of the master 23 around the plate cylinder 9 is performed. When the master 23 for one plate is made, the operations of the platen roller 18 and each of the master transport roller pairs 21 and 22 are stopped, and the master cutting means 20 is operated to cut the master 23. The cut master 23 is pulled out from the plate making section 3 by the rotation of the plate cylinder 9, and after the master 23 is wound, the plate cylinder 9 stops at the home position, thereby completing the plate making operation and the plate feeding operation.

  The printing operation is performed following the plate feeding operation. When the plate cylinder 9 stops at the home position, the paper feed roller 27 and the separation roller pair 28 rotate to pull out the uppermost sheet P from the paper feed tray 26, and the plate cylinder 9 is rotated clockwise in FIG. Driven at low speed. Only one sheet of the drawn paper P is separated and fed, and the leading end thereof is sandwiched between the registration roller pair 29. Then, the registration roller pair 29 is rotated at a predetermined timing when the leading end of the image area in the rotation direction of the plate cylinder of the master 23 wound around the plate cylinder 9 reaches the contact portion with the press roller 10, and the sheet P is transferred to the plate cylinder. 9 is fed toward the contact portion between the press roller 10 and the press roller 10. Almost simultaneously with the rotation of the registration roller pair 29, the press roller 10 presses the peripheral surface thereof against the outer peripheral surface of the plate cylinder 9 by the operation of a swinging means (not shown), and the fed paper P contacts the master 23 on the plate cylinder 9. Press contact. By this pressing operation, the press roller 10, the paper P, the master 23, and the plate cylinder 9 are pressed against each other, and the ink supplied to the inner peripheral surface of the plate cylinder 9 by the ink roller 12 oozes out from the opening portion of the plate cylinder 9, After being filled in the porous support of the master 23, it is transferred to the paper P through the perforated part of the master 23, and so-called printing is performed.

  The sheet P on which the image has been transferred by printing is peeled off from the outer peripheral surface of the plate cylinder 9 by the peeling claw 36, dropped downward and sent to the sheet transporting unit 37, and then sucked and transported by the sheet transporting unit 37. Then, the paper is discharged onto the paper discharge tray 38. Thereafter, the plate cylinder 9 rotates again to the home position and stops, and the stencil printing apparatus 1 enters a printing standby state after finishing the plate attaching operation.

  After the stencil printing apparatus 1 is in a print standby state, when a printing condition is input with various keys on the operation panel and then a test printing key (not shown) is pressed, the plate cylinder 9 is faster than the time of plate printing. The sheet rotates at a peripheral speed corresponding to the set printing speed, and only one sheet P is fed from the sheet feeding unit 4, and a test printing is performed in the same manner as at the time of printing. When a print start key (not shown) is pressed after the image position and image density are confirmed by trial printing and the number of prints is set on the operation panel, the paper P is continuously fed from the paper feed unit 4. The printing operation is performed in the same manner as the trial printing. When the set number of prints is consumed, the plate cylinder 9 stops at the home position, and the stencil printing apparatus 1 enters the print standby state again.

  During the above-described paper feeding operation, the paper P fed from the bank paper feeding device 25 is transported by the transport roller pair 56 as shown in FIG. The sheet feeding was stopped after a predetermined deflection was formed by abutting against the nip portion. Then, the registration roller pair 29 is driven to rotate by a driving unit (not shown), so that the leading edge of the sheet P is conveyed to the printing unit 2 by the conveying force of only the registration roller pair 29. At this time, after the registration roller pair 29 starts to rotate, the conveyance roller pair 56 starts to rotate after a certain waiting time, continuously maintaining the bending of the formed paper P and reducing the load on the registration roller pair 29. However, the occurrence of image position deviation due to variations in the amount of paper transport has been reduced.

As described above, in the paper feeding from the bank paper feeding device 25, the paper feeding assist mechanism (mechanism for reducing the load of the registration roller pair 29) by the transport roller pair 56 has been implemented. Since the paper feed roller 27 is also actuated when the separation roller 28 is actuated on the paper, the large size is required in the operation time corresponding to the small size paper (A5, B5, etc.) due to the length of the paper P in the transport direction. paper (B4, A3, etc.) load of the sheet feeding portion 4 while does not reach the print unit 2 is registration error is generated applied to the pair of registration rollers 29, small-sized paper is paper in operation time to match the large size sheet There is a problem in that the operation time longer than the length causes the second sheet of paper P to be fed, and registration misalignment occurs due to paper jam or misfeed start position deviation.

An embodiment of the present invention that solves the above-described problems will be described below.
As shown in FIG. 3, when the paper feed motor 31 is driven, both the paper feed roller 27 and the separation roller 28 rotate, so that only the uppermost paper P on the paper feed tray 26 is separated and fed. The separated paper P is transported to the registration roller pair 29, but the leading end is detected by the sensor 49, and after being abutted against the nip portion of the registration roller pair 29, it is transported by a predetermined amount to bend. . The sheet P on which the deflection is formed is conveyed to the printing unit 2 by driving the registration roller pair 29. At this time, the paper feed assist mechanism is configured to convey the paper P while maintaining the bending formed by rotating the separation roller 28 in synchronization with the rotation start of the registration roller pair 29. When the printing speed is set to a high speed (120 cpm or more), the driving means of the registration roller pair 29 is driven at a higher speed in the same time, so that the acceleration curve rises (slopes) and the acceleration load increases. .

  In the present embodiment, the driving time (paper transport distance) of the separation roller 28 is controlled particularly in the region where the acceleration load with a high printing speed increases in the paper feed assist mechanism. The distance to the pair 29 is set as a predetermined value, and a length equal to or shorter than the length obtained by subtracting the predetermined value from the length of the paper P is set as the paper feed assist operation time. When the paper length is shorter than the predetermined value, the paper feed assist operation is not performed. As a predetermined value, a length obtained by adding an error such as an excessive feed amount at the time of forming a deflection and an error such as a conveyance slip depending on a sheet type in addition to a distance from the sheet feeding roller 27 to the registration roller pair 29 is regarded as a margin value. The margin value is generally set to about 5 to 10 mm, and the predetermined value is almost a fixed value for each stencil printing apparatus.

  FIG. 4 shows a block diagram of the control means 48 for driving and controlling the paper feed motor 31. In the present embodiment, the control unit 48 controls the operation of the paper feed motor 31 based on the paper length information from the sensor 50 and the printing speed information of the stencil printing apparatus 1 sent from the control unit of the stencil printing apparatus 1. Thus, the driving time of the separation roller 28 is controlled.

  With the configuration described above, when the predetermined value of the stencil printing apparatus 1 is 150 mm and the B5 size is conveyed in the longitudinal direction as the paper P, the paper length is 182 mm, so the value obtained by subtracting the predetermined value 150 mm from 182 mm is 32 mm. The following is the paper feed assist operation, that is, the transport distance of the separation roller 28. When the assist operation is performed for the paper P shorter than the predetermined value, the second paper P is fed, and the registration deviation due to the paper feeding jam or the feeding start position deviation occurs, so that the operation is not performed.

  According to the above-described configuration, the registration roller pair 29 allows the paper P to be fed in response to an increase in paper conveyance speed and an increase in paper types in any paper feeding unit 4 without increasing the size of the registration driving means. In order to prevent the sheet formed on the upstream side in the sheet feeding direction of the registration roller pair 29 from being bent during feeding, and to prevent the sheet from bending due to an excessive amount of bending. It is possible to provide the paper feeding device 4 capable of controlling the paper conveyance speed of the roller 28.

  In the above-described embodiment, the margin value added to the predetermined value may be set according to at least one of the paper type, temperature, humidity, and image forming speed. As a result, a finer paper feed assist operation can be performed, and better image formation can be continued.

  In the above embodiment, an example in which a stencil printing apparatus is used as an image forming apparatus has been described. However, an image forming apparatus to which the present invention can be applied is not limited to this, and a copying machine, a printer, a plotter, a facsimile, a complex machine of these, or the like The present invention can also be applied to other image forming apparatuses.

1 Image forming device (stencil printing device)
4 Paper feeder (paper feeder)
27 Paper feed roller 28 Separation roller 29 Registration roller pair 50 Paper size detection means (paper size detection sensor)
P paper

Japanese Patent No. 4344028 JP 2011-121653 A

Claims (6)

A sheet feed roller that is driven to rotate and a separation roller that is driven to rotate in synchronization with the sheet feed roller, and separates the sheets one by one toward the registration roller pair of the image forming apparatus while forming the sheet deflection. In a paper feeder that can change the paper feed drive time for feeding,
A paper size detection unit that detects a paper size in a paper feeding direction, and the driving time of the separation roller when the registration roller pair is driven when the paper size detected by the paper size detection unit exceeds a predetermined value , And the predetermined value is a distance between the registration roller pair and the paper feed roller . A sheet feed roller that is driven to rotate and a separation roller that is driven to rotate in synchronization with the sheet feed roller, and separates the sheets one by one toward the registration roller pair of the image forming apparatus while forming the sheet deflection. In a paper feeder that can change the paper feed drive time for feeding,
A paper size detection unit that detects a paper size in a paper feeding direction, and the driving time of the separation roller when the registration roller pair is driven when the paper size detected by the paper size detection unit exceeds a predetermined value , And the predetermined value is a value obtained by adding a margin value to the distance between the pair of registration rollers and the paper feed roller . The paper feeding device according to claim 2 .
The paper supply apparatus, wherein the margin value is determined according to a paper type . The paper feeding device according to claim 2 .
The paper supply apparatus, wherein the margin value is determined according to temperature or humidity . The paper feeding device according to claim 2 .
The paper supply apparatus, wherein the margin value is determined according to an image forming speed . An image forming apparatus comprising the paper feeding device according to claim 1.

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