JP2017206331A - Sheet discharge device and image formation apparatus having the same - Google Patents

Abstract

A sheet discharge device and an image forming apparatus including the sheet discharge device capable of effectively correcting upward curling generated at the end portion in the width direction of the sheet are provided.
A sheet discharge device includes a sheet discharge port, a conveyance guide, a discharge roller pair, and a curl correction member. The conveyance guide guides the sheet to the sheet discharge port. A plurality of discharge roller pairs are provided in the vicinity of the sheet discharge port. The curl correction member is arranged between the discharge roller pair arranged on the outermost side in the sheet width direction from the plurality of discharge roller pairs to both edges in the width direction of the sheet passing through the discharge roller pair, and presses the sheet from above. And correct the upward curl. The curl correction member has a plate-like pressing piece that protrudes substantially perpendicularly below the nip portion of the discharge roller pair and contacts the upper surface of the sheet. The pressing piece is disposed so as to be inclined outward in the sheet width direction from the upstream side in the sheet discharge direction toward the downstream side.
[Selection] Figure 4

Description

  The present invention relates to a sheet discharging apparatus that discharges sheet-like paper or a document used in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and an image forming apparatus including the sheet discharging apparatus.

  In an image forming apparatus using an electrophotographic system, a toner image is formed by applying toner to an electrostatic latent image formed on an image carrier such as a photosensitive drum, and the toner image is formed into a sheet-like recording medium such as paper. Then, the toner image on the paper is fixed by a fixing device (fixing unit).

  In such an image forming apparatus, the paper heated and pressed by the fixing device may be largely curled (rolled) depending on conditions. When the paper is curled locally in this way, the paper discharge port is blocked, and the alignment and stackability of the paper discharged onto the discharge tray are significantly impaired, and the previously loaded paper is pushed out in the discharge direction. There was also a risk of falling from the discharge tray.

  Therefore, various methods for correcting the curl of the paper have been proposed. For example, Patent Document 1 extends from the nip portion of the discharge roller pair to the upstream side in the sheet conveyance direction, and presses in contact with the sheet. Thus, a sheet conveying apparatus is disclosed in which a seating member for sticking the sheet is arranged.

Japanese Patent Laying-Open No. 2015-67416

  In the configuration of Patent Document 1, a sheeting member is disposed between a plurality of discharge roller pairs so that the sheet is corrugated along the width direction. Therefore, there is a problem that the upward curl generated at the end in the width direction of the sheet cannot be effectively corrected.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet discharge device that can effectively correct upward curling that occurs at an end portion in the width direction of a sheet, and an image forming apparatus including the sheet discharge device.

  In order to achieve the above object, a first configuration of the present invention includes a sheet discharge port, a conveyance guide, a discharge roller pair, and a curl correction member, and sequentially discharges and stacks sheets on a discharge tray. A sheet discharge device. The sheet is discharged from the sheet discharge port. The conveyance guide includes an upper conveyance guide that faces the upper surface of the sheet and a lower conveyance guide that faces the lower surface of the sheet, and guides the sheet to the sheet discharge port. A plurality of discharge roller pairs are provided in the vicinity of the sheet discharge port. The curl correction member is arranged between the discharge roller pair arranged on the outermost side in the sheet width direction from the plurality of discharge roller pairs to both edges in the width direction of the sheet passing through the discharge roller pair, and presses the sheet from above. And correct the upward curl. The curl correction member has a plate-like pressing piece that protrudes substantially perpendicularly below the nip portion of the discharge roller pair and contacts the upper surface of the sheet. The pressing piece is disposed so as to be inclined outward in the sheet width direction from the upstream side in the sheet discharge direction toward the downstream side.

  According to the first configuration of the present invention, the contact position of the pressing piece is set as the sheet is discharged by the pressing piece that is inclined outward in the sheet width direction from the upstream side to the downstream side with respect to the sheet discharging direction. Move outward in the width direction. As a result, both end portions in the width direction of the sheet are pressed downward while being spread from the inside toward the outside by the pressing pieces, so that it is possible to effectively correct the upper curl generated at both ends in the width direction of the sheet. .

Side sectional view showing the internal structure of the image forming apparatus 100 in which the paper discharge device 30 of the present invention is mounted. 1 is a front view of a paper discharge device 30 according to an embodiment of the present invention as viewed from the downstream side in the paper discharge direction. Side sectional view of the paper discharge device 30 of the present embodiment The perspective view which looked at the curl correction member 35 used for the paper discharge apparatus 30 of this embodiment from the outer side in the paper width direction. The perspective view of the support part 37 which comprises the curl correction member 35 The perspective view of the press part 39 which comprises the curl correction member 35 A plan view of the curl correction member 35 as viewed from above. View of the curl correction member 35 as seen from the upstream side in the paper discharge direction Side view of the pressing piece 39b with which the leading edge S1 of the paper S is in contact A perspective view of the pressing piece 39b contacted with the leading edge S1 of the paper S as viewed from the upstream side in the paper discharging direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an internal structure of an image forming apparatus 100 on which a paper discharge device 30 (see FIG. 2) according to an embodiment of the present invention is mounted. As shown in FIG. 1, in an image forming apparatus (for example, a monochrome printer) 100, an image forming portion P that forms a monochrome image by each process of charging, exposure, development, and transfer is disposed. In the image forming portion P, along the rotation direction of the photosensitive drum 5 (clockwise direction in FIG. 1), the charging unit 4, the exposure unit (laser scanning unit, etc.) 7, the developing unit 8, the transfer roller 14, and the cleaning device 19 and a static eliminator (not shown) are disposed.

  When the image forming operation is performed, the photosensitive drum 5 rotating in the clockwise direction is uniformly charged by the charging unit 4, and the electrostatic latent image is formed on the photosensitive drum 5 by the laser beam from the exposure unit 7 based on the document image data. An image is formed, and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by the developing unit 8 to form a toner image.

  The toner is supplied to the developing unit 8 from the toner container 9. The image data is transmitted from a personal computer (not shown) or the like. Further, a static elimination device (not shown) for removing residual charges on the surface of the photosensitive drum 5 is provided on the downstream side of the cleaning device 19.

  The sheet is conveyed from the sheet feeding cassette 10 via the sheet conveyance path 12 and the registration roller pair 13 toward the photosensitive drum 5 on which the toner image is formed as described above, and is transferred by the transfer roller 14 (image transfer unit). A toner image formed on the surface of the photosensitive drum 5 is transferred to a sheet. The sheet on which the toner image has been transferred is separated from the photosensitive drum 5 and conveyed to the fixing device 15 to fix the toner image.

  The paper that has passed through the fixing device 15 and the transport roller pair 23 is transported to the upper portion of the image forming apparatus 100 through the paper transport path 16, and when an image is formed on only one side of the paper (at the time of single-side printing), the paper discharge device 30. The paper is discharged to a discharge tray 18 via a discharge roller pair 17 (see FIG. 2).

  On the other hand, when images are formed on both sides of the paper (during double-sided printing), the discharge roller pair 17 is reversely rotated after the trailing edge of the paper has passed through the branch portion 20 of the paper conveyance path 16 to reverse the conveyance direction. As a result, the paper is distributed from the branching portion 20 to the reverse conveyance path 21 and is re-conveyed to the registration roller pair 13 with the image surface reversed. Then, the next toner image formed on the photosensitive drum 5 is transferred by the transfer roller 14 to the surface on which the sheet image is not formed. The sheet on which the toner image has been transferred is conveyed to the fixing device 15 to fix the toner image, and then discharged onto the discharge tray 18 via the discharge roller pair 17.

  2 is a front view of the paper discharge device 30 mounted on the image forming apparatus 100 as viewed from the downstream side in the paper discharge direction (left side in FIG. 1). FIG. 3 includes a support portion 37 of the curl correction member 35. 3 is a side cross-sectional view of the paper discharge device 30 (a cross-sectional view taken along arrow AA ′ in FIG. 2). The paper discharge device 30 includes a paper discharge port 31, a conveyance guide 32 including an upper conveyance guide 32a and a lower conveyance guide 32b for guiding the paper to the paper discharge port 31, a discharge roller pair 17, a corrugation member 33, and a curl correction. Member 35.

  Four pairs of discharge rollers 17 are arranged substantially evenly in the paper width direction (arrow X direction in FIG. 2) in the immediate vicinity of the upstream side of the paper discharge port 31, and discharge the paper conveyed from the paper conveyance path 11 to the discharge tray. 18 (see FIG. 1). Each discharge roller pair 17 includes a rubber discharge roller 17a that can be rotated forward and backward by a drive motor (not shown), and a resin discharge roller 17b that rotates following the discharge roller 17a (see FIG. 3 for both). It consists of and.

  A corrugation member 33 that presses the upper surface of the paper discharged from the paper discharge port 31 is disposed between each discharge roller pair 17. The corrugation member 33 is supported by the upper conveyance guide 32a so as to be movable in the vertical direction, and is urged downward by a compression spring (not shown). The lower end portion 33 a of the corrugation member 33 is located below the nip portion N of the discharge roller pair 17.

  The paper discharged from the paper discharge port 31 is nipped by the nip portion N of the discharge roller pair 17 and pressed downward from the nip portion N by the lower end portion 33 a of the corrugation member 33. As a result, the sheet is bent into a wave shape when viewed from the discharge direction, and is discharged onto the discharge tray 18 in a state of being stiff. Accordingly, it is possible to prevent a problem that the leading edge of the sheet is discharged in a state where the leading edge hangs downward due to its own weight, and the leading edge is stuck on the upper surface of the discharge tray 18 and is stacked in a rounded state.

  Further, a curl correction member 35 is disposed on the outer side of the discharge roller pair 17 located on the outermost side in the paper width direction (left and right direction in FIG. 2). The curl correction member 35 corrects upward curl (upper curl) generated at both ends in the width direction of the paper.

  4 is a perspective view of the curl correction member 35 as viewed from the outside in the paper width direction, FIG. 5 is a support portion 37 constituting the curl correction member 35, and FIG. 6 is a pressing portion constituting the curl correction member 35. FIG. 4 to 6 show the curl correcting member 35 disposed on one end side (the right end in FIG. 2) of the paper discharge port 31, but on the other end side (the left end in FIG. 2) of the paper discharge port 31. The arranged curl correction member 35 has the same configuration except that it is symmetrical. The curl correction member 35 includes a support portion 37 attached to the upper conveyance guide 32a and a pressing portion 39 fixed to the support portion 37 (see FIGS. 5 and 6).

  The support portion 37 is made of resin, and includes a main body portion 37a, two engaging claws 37b that protrude upward from the main body portion 37a, and a support piece 37c that protrudes horizontally from the main body portion 37a. The main body portion 37a is formed with an arc-shaped first cutout portion 40a (see FIG. 5) for preventing interference with the rotation shaft 17a1 (see FIG. 3) of the discharge roller 17a. The engagement claw 37b engages with an engagement hole 50 (see FIG. 3) formed in the upper conveyance guide 32a. The fixing piece 39a of the pressing portion 39 is bonded and fixed to the support piece 37c. The support piece 37c is divided into two in the paper discharge direction (arrow B direction) in order to prevent interference with the rotation shaft 17a1 of the discharge roller 17a (see FIGS. 5 and 6).

  The pressing portion 39 is formed of an elastic material such as rubber, and includes a fixing piece 39a that is bonded and fixed to the support piece 37c of the support portion 37, and a pressing piece 39b that extends vertically downward from one end of the bonding portion 39a. . The pressing piece 39b is formed with an inclined portion 41 whose height (projection amount d from the fixed piece 39a) increases from the upstream side to the downstream side (the direction of arrow B in FIG. 6) with respect to the paper discharge direction. On the downstream side of the inclined portion 41, a substantially horizontal protruding portion 42 having a maximum protruding amount d is formed. The pressing piece 39b is formed with an arc-shaped second notch 40b for preventing interference with the rotation shaft 17a1 of the discharge roller 17a.

  7 is a plan view of the curl correction member 35 as viewed from above, and FIG. 8 is a view of the curl correction member 35 mounted on the upper surface 31a of the paper discharge port 31 as viewed from the upstream side in the paper discharge direction. . As shown in FIG. 7, the pressing piece 39b is in the paper width direction from the upstream side to the downstream side (from the bottom of FIG. 7, from the front side to the back side of FIG. 8) with respect to the paper discharge direction (arrow B direction). It is arranged to incline to the outside. Further, the lower end portion (horizontal portion excluding the inclined portion 41) of the pressing piece 39b protrudes below a nip portion N (see FIG. 3) of the discharge roller pair 17 by a predetermined amount (here, 5 mm), and the paper discharge direction Is disposed at a position overlapping the nip portion N from the upstream side to the downstream side.

  Next, the principle of correcting the upward curl generated at both ends in the width direction of the paper by the curl correction member 35 will be described. FIG. 9 is a side view of the pressing piece 39b in contact with the leading edge S1 of the paper S, and FIG. 10 is a perspective view of the pressing piece 39b in contact with the leading edge S1 of the paper S as viewed from the upstream side in the paper discharging direction. The leading edge S1 of the sheet S conveyed through the sheet conveying path 16 contacts the inclined portion 41 formed on the pressing piece 39b of the curl correction member 35. The sheet S is smoothly conveyed along the inclined portion 41 to the downstream side in the conveyance direction without being caught by the pressing piece 39b.

  Here, as shown in FIG. 7, the pressing piece 39b is inclined outward in the paper width direction from the upstream side to the downstream side with respect to the paper discharge direction (arrow B direction). As a result, as the paper S is discharged, the contact position of the pressing piece 39b moves outward in the width direction of the paper S. As a result, both end portions in the width direction of the sheet S are pressed downward while being spread from the inside toward the outside by the pressing pieces 39b, so that the upper curl generated at both ends in the width direction of the sheet S is effectively corrected. be able to.

  The curl correction member 35 is disposed at a position facing the curled portion of the paper between the outer side of the discharge roller pair 17 located on the outermost side in the paper width direction and both ends of the paper in the width direction. Specifically, for example, in the case of A4 size paper, the paper width is 297 mm, and both end portions in the width direction of the paper are 148.5 mm from the center of the paper. Further, the position where the upper curl occurs is about 30 mm from both ends in the width direction of the paper. Therefore, the pressing piece 39b of the curl correction member 35 may be arranged so that the upstream end (the lower end in FIG. 7) is 118.5 mm from the center of the paper.

  Further, by setting the width W of the downstream end portion of the pressing piece 39b shown in FIG. 7 (the contact width of the sheet from the upstream end portion to the downstream end portion) to 30 mm or more, the entire area of the curled portion is the pressing piece 39b. The curl correction effect is further improved.

  Further, since the pressing portion 39 can be elastically deformed in the paper width direction with the upper end edge as a fulcrum, the pressing piece 39b is in the paper width direction (the arrow direction in FIG. 10) when the leading edge of the paper S comes into contact as shown in FIG. Bend. Thereby, the impact when the paper S comes into contact with the pressing piece 39b is alleviated, and the upper curl can be corrected without causing the leading edge of the paper S to be turned up.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above-described embodiment, the engagement holes 50 with which the engagement claws 37b of the support portion 37 are engaged are provided at two positions (one position in the sheet width direction) at both ends of the upper conveyance guide 32a in the sheet width direction. However, if the engagement holes 50 are formed at a plurality of positions in the sheet width direction facing the vicinity of both end edges of a plurality of types of sheet sizes, the curl correction member 35 can be replaced according to the size of the sheet to be discharged. Thus, it is possible to correct the upper curl generated on a plurality of types of paper.

  The present invention is not limited to the monochrome printer as shown in FIG. 1, but is connected to other types of image forming apparatuses such as color printers, monochrome and color copiers, digital multifunction peripherals, facsimiles, and the like, and image forming apparatuses. Of course, the present invention can also be applied to a paper post-processing apparatus.

  The present invention can be used in a sheet discharge device that discharges sheet-like paper or a document. By utilizing the present invention, it is possible to provide a sheet discharge device capable of effectively correcting upward curling generated at the end in the width direction of the sheet, and an image forming apparatus including the sheet discharge device.

15 Fixing device 16 Paper transport path (sheet transport path)
17 discharge roller pair 17a discharge roller 17b discharge roller 18 discharge tray 30 paper discharge device (sheet discharge device)
31 Paper outlet (sheet outlet)
32 conveyance guide 32a upper conveyance guide 32b lower conveyance guide 33 corrugation member 35 curl correction member 37 support portion 37a body portion 37b engagement claw 37c support piece 39 pressing portion 39a fixing piece 39b pressing piece 41 inclined portion 42 protruding portion 100 image forming apparatus P Image forming unit

Claims (7)

A sheet discharge port through which the sheet is discharged;
A conveyance guide configured to include an upper conveyance guide opposed to the upper surface of the sheet and a lower conveyance guide opposed to the lower surface of the sheet, and to guide the sheet to the sheet discharge port;
A plurality of discharge roller pairs provided in the vicinity of the sheet discharge port;
In a sheet discharge device that sequentially discharges and stacks sheets on a discharge tray,
The sheet is pressed upward from above between the discharge roller pair arranged on the outermost side in the sheet width direction from the discharge roller pair to both ends in the width direction of the sheet passing through the discharge roller pair. A curl correction member that corrects curl is provided,
The curl correction member has a plate-like pressing piece that protrudes substantially vertically below the nip portion of the discharge roller pair and contacts the upper surface of the sheet, and the pressing piece is from the upstream side in the sheet discharging direction. A sheet discharging apparatus, wherein the sheet discharging apparatus is disposed so as to be inclined outward in the sheet width direction toward the downstream side.   2. The sheet discharge according to claim 1, wherein the pressing piece has an inclined portion that is inclined downward from an upstream side in the sheet discharge direction toward a downstream side at an upstream end portion in the sheet discharge direction. apparatus.   The pressing piece has a protruding portion having a maximum protruding amount on the downstream side of the inclined portion in the sheet discharging direction, and the protruding portion is downstream from the upstream side of the nip portion of the discharging roller pair in the sheet discharging direction. The sheet discharging apparatus according to claim 1, wherein the sheet discharging apparatus is disposed over the entire area.   The sheet discharge device according to any one of claims 1 to 3, wherein the pressing piece is elastically deformable in a sheet width direction with an upper end edge as a fulcrum.   The said curl correction member is comprised by the press part containing the said press piece, and the support part which can attach or detach with respect to the said upper conveyance guide while supporting this press part. 5. The sheet discharging apparatus according to any one of 4 above.   The sheet discharging apparatus according to claim 5, wherein the support portion can be selectively attached to a plurality of portions of the upper conveyance guide that face the vicinity of both end edges in the width direction of the plurality of types of sheets.   An image forming apparatus comprising the sheet discharge device according to claim 1.

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