JP2009001351A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of reducing the noise emitted when a sheet is being fed. <P>SOLUTION: A guide part 20a is provided to constitute the upstream side portion in the sheet feeding direction of a sheet transport path R which transports a sheet P sent out by a sheet feeding device. A holding member 5b holds a sheet separating member 5a which separates the sheet P in pressure contact with a sheet feeding member 4 and sent out thereby, and the downstream side end in the sheet feeding direction of this holding member 5b is inclined to the direction of eliminating a step with respect to a rib 20b formed protrusively on the guide part 20a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to a configuration for reducing noise during sheet feeding.

  A conventional image forming apparatus includes a sheet feeding device that feeds a sheet to an image forming unit. As such a sheet feeding device, for example, a sheet feeding member that feeds a sheet from a sheet stacking unit on which sheets are stacked, and a sheet separating unit that separates the sheets fed by the sheet feeding member one by one There is something to prepare.

  Here, as the sheet separating unit, for example, a sheet separating member, which is a friction member such as a separation pad, is pressed against the sheet feeding member to prevent double feeding of sheets, and only the topmost sheet is fed one by one. There is a method.

  On the other hand, some conventional image forming apparatuses have a curved sheet conveyance path for conveying sheets separated one by one by a sheet separating unit, for example, in order to reduce the size and the installation area.

  Here, the sheet separation unit and the sheet conveyance path are usually separated from each other in terms of maintenance and the like. However, when the sheet separating unit and the sheet conveyance path are separated from each other as described above, when the trailing end of the sheet is removed from the sheet separating unit, the sheet is repelled by its rigidity and the weight of the sheet (difference in potential energy). Behaves like this.

  Due to the behavior of the sheet, the rear end of the sheet collides with the guide portion that forms the upstream end of the sheet conveyance path in the sheet feeding direction, and an impact sound is generated at that time. Therefore, as a means for reducing such impact noise, there is one that reduces the impact noise by providing a convex portion on a part of the guide portion to narrow the area where the sheet collides with the guide portion (patent) Reference 1).

  7, 8 and 9 are diagrams showing the configuration of a conventional image forming apparatus having such a configuration. 7, 8, and 9, reference numeral 104 denotes a paper feed roller, and 105 a denotes a separation pad. A sheet separation unit is formed by the paper feed roller 104 and the separation pad 105 a. Reference numeral 105 b denotes a separation pad arm that holds the separation pad 105 a, and the separation pad 105 a is pressed against the paper feed roller 104 by urging the separation pad arm 105 b by the urging member 119.

  Reference numeral 118 denotes a holding member that rotatably holds the separation pad arm 105b in the vertical direction, and R denotes a curved sheet conveyance path. Reference numeral 120a denotes a first conveyance guide constituting the upstream end of the sheet conveyance path R in the sheet feeding direction, and 120b denotes a second conveyance guide protruding from the first conveyance guide 120a.

  In the conventional image forming apparatus having such a configuration, when the trailing edge of the sheet P passes through the separation nip N formed by the sheet feeding roller 104 and the separation pad 105a shown in FIG. Passes the downstream end portion P1 of the separation pad arm 105b in the sheet feeding direction. Next, the rear end of the sheet comes into contact with the second conveyance guide 120b at the position indicated by P2, and is then conveyed along the first conveyance guide 120a and the second conveyance guide 120b.

  By the way, when the trailing edge of the sheet moves from P1 to P2 as indicated by the arrow C in this way, the trailing edge of the sheet moves suddenly and collides with the second conveyance guide 120b. Here, as shown in FIG. 8, the second conveyance guide 120b has a smaller area in contact with the sheet than the first conveyance guide 120a.

  For this reason, even if the trailing edge of the sheet collides with the second conveyance guide 120b, the impact sound can be reduced as compared with the case where the trailing edge of the sheet collides with the first conveyance guide 120a. With this configuration, noise during sheet feeding can be reduced.

JP-A-8-169589

  Incidentally, in recent years, the image forming apparatus has been required to be further downsized so as to reduce the installation area. For this reason, for example, the sheet conveyance path is curved more greatly. On the other hand, as the sheet P on which an image is formed, a thick and thick sheet is often used due to the spread of photographic printing and the like.

  Here, when a thick and stiff sheet is conveyed toward a largely curved sheet conveyance path, when the sheet comes out from the sheet separation unit, the trailing edge of the sheet can be repelled more greatly. Thereby, even when the rear end of the sheet is caused to collide with the second conveyance guide 120b for reducing the impact sound, the impact sound is increased, and as a result, a large noise is generated.

  As described above, in the conventional image forming apparatus in which the sheet conveyance path is greatly curved for downsizing, when a thick sheet is fed, a larger noise is generated.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can reduce noise when a sheet is fed.

  The present invention provides a sheet feeding member that feeds a sheet, a sheet feeding device having a sheet separating member that presses against the sheet feeding member and separates a sheet fed by the sheet feeding member, and the sheet feeding device. In the image forming apparatus including the sheet conveying path for conveying the sheet, a holding member that holds the sheet separating member, and a guide unit that is positioned downstream of the holding member in the sheet feeding direction and guides the sheet. And the downstream end of the holding member in the sheet feeding direction is inclined in a direction that eliminates a step with the guide.

  As in the present invention, the downstream end portion in the sheet feeding direction of the holding member that holds the sheet separating member is inclined in a direction that eliminates the step with the guide portion that forms the upstream portion in the sheet feeding direction of the sheet conveying path. As a result, it is possible to reduce noise when the sheet is fed.

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

  FIG. 1 is a diagram showing a schematic configuration of an electrophotographic printer which is an example of an image forming apparatus according to a first embodiment of the present invention.

  In FIG. 1, 50 is a printer, 51 is a printer main body, 52 is provided in the printer main body 51, and forms an image by an electrophotographic method. 53 is a sheet feeding unit that feeds a sheet P to the image forming unit 52. Device.

  Here, the image forming unit 52 includes a photosensitive drum 10a for forming a toner image, a transfer roller 11 for transferring the toner image formed on the photosensitive drum 10a to the sheet P, and the like. Reference numeral 10 denotes a process cartridge including a photosensitive drum 10a, a charging roller 10c fed from a high voltage power supply (not shown), a developing sleeve 10d, a toner container 10b, a cleaning blade 10e, and a waste toner container 10f. The process cartridge 10 is detachably attached to the printer main body 51.

  When an image forming operation is started in the image forming unit 52 having such a configuration, first, light corresponding to an image signal is charged from the laser exposure device 17 by the charging roller 10c, and the surface is charged. The photosensitive drum 10a that is driven to rotate is irradiated. Then, by irradiating light according to such an image signal, a latent image is formed on the photosensitive drum.

  Next, after the toner charged in the toner container 10b is appropriately charged as the developing sleeve 10d rotates, the toner is supplied onto the photosensitive drum 10a and adheres to the electrostatic latent image on the photosensitive drum 10a. Thus, the latent image is developed and visualized as a toner image.

  The sheet feeding device 53 is fed by the sheet feeding tray 1 provided in the printer main body 51 so as to be openable and closable, the sheet feeding roller 4 for feeding the sheet P stored in the sheet feeding tray 1, and the sheet feeding roller 4. And a sheet separating unit 5 that separates the sheet P. Reference numeral 6 denotes a paper feed shaft on which the paper feed roller 4 is mounted.

  Here, the sheet feeding tray 1 includes a sheet width regulating plate 2 that regulates both end positions in a direction (hereinafter referred to as a width direction) orthogonal to the sheet conveyance direction of the sheet P. A sheet feeding pressure plate 3 that presses the sheets P stacked on the sheet feeding tray 1 against a sheet feeding roller 4 that is a sheet feeding member is rotatably provided downstream of the sheet feeding tray 1 in the sheet feeding direction. Yes. The sheet feeding pressure plate 3 is biased toward the sheet feeding roller by a spring 3a.

  The sheet separation unit 5 includes a separation pad 5a that is a sheet separation member that is in pressure contact with the paper feed roller 4, and a separation pad arm 5b that is a holding member that holds the separation pad 5a. Further, the sheet separation unit 5 includes a separation pad spring 19 that urges the separation pad arm 5 b toward the paper feed roller to press the separation pad 5 a against the paper feed roller 4. Reference numeral 18 denotes a separation pad holder configured to hold the separation pad arm 5b in a rotatable manner and to be detachable from the printer main body 51.

  In such a sheet feeding device 53, in parallel with the toner image forming operation as described above, the sheet P is fed from the sheet feeding tray 1 by the sheet feeding roller 4, and then the sheet is separated by the sheet separating unit 5. They are separated one by one. Note that the sheet P separated by the sheet separating unit 5 in this way is positioned downstream of the sheet separating unit 5 (sheet feeding device 53) in the sheet feeding direction, and is curved in the direction of the image forming unit 52. It is conveyed to the path R.

  Next, an image forming operation in the printer 50 having such a configuration will be described.

  After the sheet P to which the toner is transferred is set on the paper feed tray 1 and the paper feed pressure plate 3, when a print start signal is input, the motor 16 rotates. The rotation of the motor 16 drives the paper feed roller 4, the transport roller 8, the photosensitive drum 10a, the fixing pressure roller 13, the paper discharge roller 14, and the like in the sheet transport direction (arrow A direction).

  As a result, first, the sheet P set on the paper feed tray 1 and the paper feed pressure plate 3 is sent out by friction with the paper feed roller 4. Here, the paper feed roller 4 feeds the sheet P in the direction of the arrow by one rotation by a single rotation control unit (not shown).

  A paper feed cam (not shown) for regulating the position of the rotatable paper feed pressure plate 3 is attached to the paper feed shaft 6 to which the paper feed roller 4 is detachably attached. It rotates with the paper feed roller 4. The sheet feeding pressure plate 3 rotates upward in conjunction with the rotation of the sheet feeding cam, and presses the sheet P against the sheet feeding roller 4. Further, the sheet P is guided by the sheet width regulating plate 2 when being fed by the sheet feeding roller 4.

  On the other hand, simultaneously with the rotation of the paper feed roller 4, the sheets P are separated one by one by the separation pad 5a urged by the separation pad spring 19 and fed. Immediately before the end of one rotation of the paper feed roller 4, the paper feed cam provided on the same axis as the paper feed shaft 6 pushes down the paper feed pressure plate 3 to the paper feed standby position. Return to the paper standby position.

  Next, the sheet P sent out by one rotation of the paper feeding roller 4 is conveyed by the conveying roller 8, and a sheet leading edge detection flag 9 disposed on the upstream side of the curved sheet conveying path R in the sheet feeding direction. Defeat. A photo sensor (not shown) is attached to the sheet leading edge detection flag 9, and the sheet leading edge detection flag 9 rotates to detect the leading edge position of the sheet P. After a predetermined time, the laser exposure apparatus 17 irradiates the photosensitive drum 10a with laser light.

  As a result, an electrostatic latent image is formed on the photosensitive drum 10a, and this electrostatic latent image is developed with the appropriately charged toner supplied onto the photosensitive drum 10a by the rotation of the developing sleeve 10d. Visualize. Thereafter, the visualized toner image on the photosensitive drum 10 a is transferred onto the sheet P by the transfer roller 11.

  The untransferred toner remaining on the photosensitive drum 10a without being transferred is stored in the waste toner container 10f by the cleaning blade 10e, and the photosensitive drum 10a whose surface has been cleaned repeatedly enters the next image forming process.

  Next, the sheet P on which the toner image is formed is permanently fixed on the sheet P by being heated and pressed by a fixing device composed of the fixing heating member 12 and the fixing pressure roller 13. . Thereafter, the sheet P on which the toner image is fixed is discharged out of the printer main body by the paper discharge roller 14 and is stacked on a paper discharge tray 15 provided on the upper surface of the printer main body.

  FIG. 2 is a perspective view showing the configuration of the sheet separating unit 5 and the sheet conveying path R.

  In FIG. 2, reference numeral 20 a denotes a first conveyance guide that forms the upstream side portion of the sheet conveyance path R in the sheet feeding direction and forms a guide portion that guides the sheet. Reference numeral 20b denotes a second conveyance guide that is a rib that protrudes from the first conveyance guide 20a in the width direction and extends in the sheet feeding direction. In this way, by projecting the second conveyance guide 20b on the first conveyance guide 20a, it is possible to reduce the impact sound generated between the sheet rear end and the first conveyance guide 20a.

  In the present embodiment, the first conveyance guide 20a and the second conveyance guide 20b extend to the side of the separation nip N that is a pressure contact portion between the paper feed roller 4 and the separation pad 5a shown in FIG. Yes. As a result, the sheet P sent out by the paper feed roller 4 can surely enter the separation nip N, and the sheet P can be stably conveyed to the sheet conveyance path R.

  By the way, when the rear end of the sheet P conveyed by the paper supply roller 4 passes the separation nip N during image formation, the rear end of the sheet passes the downstream end portion P1 of the separation pad arm 5b shown in FIG. pass. Next, the rear end of the sheet comes into contact with the second conveyance guide 20b at a position indicated by reference numeral P2, and is then conveyed along the first conveyance guide 20a and the second conveyance guide 20b.

  Here, in the present embodiment, the downstream end of the separation pad arm 5b in the sheet feeding direction is inclined in a direction that eliminates the step with the second conveyance guide 20b. That is, a slope 5c is formed at the downstream end of the separation pad arm 5b in the sheet feeding direction so as to be inclined so as to eliminate a step with the second transport guide 20b as much as possible.

  The inclined surface 5c is formed so as to overlap with the second conveyance guide 20b at an obtuse angle in the width direction. Further, although the size of the step varies due to an attachment error of the separation pad arm 5b or the like, it is made as small as possible by increasing the attachment accuracy.

  For this reason, when the trailing edge of the sheet P passes through the separation nip N, the trailing edge of the sheet first lands on a part of the slope 5c of the separation pad arm 5b indicated by reference numeral P1. Next, the rear end of the sheet proceeds in the direction of the arrow C in the drawing along the inclined surface 5c inclined in the direction to eliminate the step, and then slowly arrives at the position indicated by the symbol P2 of the second conveyance guide 20b.

  As described above, the sheet rear end is moved along the inclined surface 5c inclined in the direction in which the step is eliminated, and is slowly landed on the second conveyance guide 20b. It is possible to prevent the entire surface of the transport guide 20a from colliding with the entire surface. Thereby, it is possible to reduce the impact sound generated after the trailing edge of the sheet passes through the separation nip N.

  In this manner, the downstream end of the separation pad arm 5b in the sheet feeding direction is inclined in a direction that eliminates the step with the second conveyance guide 20b, so that the rear end of the sheet exits the separation nip N and then Even when the sheet is opened, noise during sheet feeding can be reduced. As a result, it is possible to provide a printer (image feeding device) having a quiet conveyance sound.

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

  FIG. 4 is a perspective view illustrating the configuration of the sheet separation unit and the sheet conveyance path of the image forming apparatus according to the present embodiment. FIG. 5 is a cross-sectional view thereof. 4 and 5, the same reference numerals as those in FIGS. 2 and 3 indicate the same or corresponding parts.

  4 and 5, reference numeral 21 denotes an elastic member that is provided on the outer side in the width direction of the second conveyance guide 20b so that at least a part thereof protrudes from the second conveyance guide 20b. Here, the elastic member 21 is arranged so as to intersect an obtuse angle with respect to the inclined surface 5c provided on the separation pad arm 5b, similarly to the second transport guide 20b.

  By providing such an elastic member 21, after passing through the separation nip N, the rear end of the sheet that has landed on a part of the slope 5c of the separation pad arm 5b indicated by P1 is along the slope 5c in the direction of arrow C in the figure. Then, the robot slowly lands at the position indicated by the reference symbol P2 of the elastic member 21. Thereafter, the sheet P is conveyed along the first conveyance guide 20a and the second conveyance guide 20b.

  Here, by causing the rear end of the sheet to land on the elastic member 21 in this way, the impact of the sheet P generated at the portion indicated by the symbol P <b> 2 can be absorbed by the elastic member 21. That is, by providing the elastic member 21 on the outer side in the width direction of the second conveyance guide 20b so that at least a part thereof protrudes from the second conveyance guide 20b, the impact of the sheet P can be absorbed. The impact sound of the sheet P can be reduced.

  Next, a third embodiment of the present invention will be described.

  FIG. 6 is a cross-sectional view illustrating the configuration of the sheet separation unit and the sheet conveyance path of the image forming apparatus according to the present embodiment. In FIG. 6, the same reference numerals as those in FIG. 5 denote the same or corresponding parts.

  In FIG. 6, reference numeral 22 denotes an elastic member provided on the outer side in the width direction of the second conveyance guide 20b so that at least a part thereof protrudes from the second conveyance guide 20b. Here, the elastic member 22 is arranged so as to intersect an obtuse angle with respect to the inclined surface 5c provided on the separation pad arm 5b, and is higher than the second conveyance guide 20b, like the second conveyance guide 20b. It has a coefficient of friction.

  By providing such an elastic member 22, after passing through the separation nip N, the rear end of the sheet that has landed on a part of the slope 5 c of the separation pad arm 5 b indicated by P 1 is along the slope 5 c in the direction of arrow C in the figure. Then, the robot slowly lands at the position indicated by the reference symbol P2 of the elastic member 21. Thereafter, the sheet P is conveyed along the first conveyance guide 20a and the second conveyance guide 20b.

  Here, by causing the rear end of the sheet to land on the elastic member 22 in this way, the impact of the sheet P generated at the portion indicated by reference numeral P <b> 2 can be absorbed by the elastic member 22. That is, the impact of the sheet P can be absorbed by providing the second transport guide 20b outside the second transport guide 20b so that at least part of the second transport guide 20b protrudes. As a result, the impact of the sheet P can be absorbed. Sound can be reduced.

  Further, by providing such an elastic member 22, a change in the speed of the sheet rear end when the sheet rear end moves from the position P <b> 2 to the position P <b> 3 as indicated by the arrow D along the elastic member 22 is suppressed. be able to. As a result, the impact noise generated can be reduced when the trailing edge of the sheet suddenly collides with the first conveyance guide 20a at the position P3 downstream of the position P2 in the sheet feeding direction.

  Thus, the impact of the sheet P can be absorbed by providing the elastic member 22 on the outer side in the width direction of the second conveyance guide 20b so that at least a part thereof protrudes from the second conveyance guide 20b. Furthermore, it is possible to suppress the speed change of the sheet rear end when the sheet rear end moves along the elastic member 22. As a result, the impact sound of the sheet P can be reduced.

1 is a diagram illustrating a schematic configuration of an electrophotographic printer which is an example of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a perspective view illustrating a configuration of a sheet separation unit and a sheet conveyance path provided in the printer. FIG. 3 is a cross-sectional view illustrating a configuration of a sheet separation unit and a sheet conveyance path provided in the printer. FIG. 10 is a perspective view illustrating the configuration of a sheet separation unit and a sheet conveyance path of an image forming apparatus according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating configurations of a sheet separation unit and a sheet conveyance path of the image forming apparatus. FIG. 10 is a cross-sectional view illustrating configurations of a sheet separation unit and a sheet conveyance path of an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a perspective view of a main part for explaining the configuration of a conventional image forming apparatus. FIG. 8 is a perspective view illustrating a state in which a paper feeding roller and a paper feeding shaft in FIG. 7 are removed. FIG. 10 is a cross-sectional view of a main part for explaining the configuration of a conventional image forming apparatus.

Explanation of symbols

4 Feed roller 5 Sheet separation unit 5a Separation pad 5b Separation pad arm 5c Slope 20a First conveyance guide 20b Second conveyance guide 21 Elastic member 22 Elastic member 50 Printer 51 Printer main body 52 Image forming unit 53 Sheet feeding device N Separation nip P sheet R sheet conveyance path

Claims (7)

A sheet feeding member for feeding a sheet, a sheet feeding device having a sheet separating member that presses against the sheet feeding member and separates a sheet fed by the sheet feeding member, and a sheet fed by the sheet feeding device. In an image forming apparatus comprising a sheet conveying path for conveying,
A holding member for holding the sheet separating member;
A guide portion for guiding the sheet, which is located downstream of the holding member in the sheet feeding direction,
An image forming apparatus, wherein a downstream end portion of the holding member in a sheet feeding direction is inclined in a direction to eliminate a step with the guide portion. The guide part is provided with ribs,
The image forming apparatus according to claim 1, wherein a downstream end portion of the holding member in a sheet feeding direction is inclined in a direction in which a step with the rib is eliminated.   The image forming apparatus according to claim 2, wherein the rib and the downstream end portion of the holding member in the sheet feeding direction overlap at an obtuse angle in a width direction orthogonal to the sheet feeding direction.   The image forming apparatus according to claim 2, further comprising an elastic member provided so that at least a part of the rib protrudes from the rib in a width direction orthogonal to a sheet feeding direction of the rib.   The image forming apparatus according to claim 4, wherein the downstream end portion of the holding member in the sheet feeding direction overlaps the elastic member at an obtuse angle in a width direction orthogonal to the sheet feeding direction.   The image forming apparatus according to claim 4, wherein the elastic member has a higher coefficient of friction than the rib.   The image forming apparatus according to claim 2, wherein the guide portion and the rib extend at least to the side of the pressure contact portion of the sheet feeding member and the sheet separating member. .

Images