JP2007112522A - Sheet delivery mechanism and image forming device equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet delivery mechanism preventing generation of entrainment of a sheet pressing member to a sheet delivery port and jam or the like accompanying with it, and an image forming device equipped therewith. <P>SOLUTION: The sheet delivery mechanism is constituted by a pair of delivery rollers 16, the sheet delivery port 19; and the sheet pressing member 20. Projection parts 21 projecting to the outside of the sheet delivery port 19 and preventing entrainment of the sheet pressing member 20 to the inside of the sheet delivery port 19 are provided on the sheet pressing members 20 at both left and right sides of the sheet delivery port 19 (broken line portion in Fig.). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet discharge mechanism for discharging a sheet-like paper or a document used in an image forming apparatus such as a digital copying machine or a laser printer, and an image forming apparatus including the same.

  The configuration of a conventional image forming apparatus is shown in FIG. In an image forming apparatus (for example, a printer) 1, when performing an image forming operation, a photosensitive drum 5 that rotates clockwise in the drawing is uniformly charged by a charging unit 4, and an exposure unit (laser scanning unit) based on document image data. Etc.) An electrostatic latent image is formed on the photosensitive drum 5 by the laser beam from 7, 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 18.

  A sheet is conveyed from the sheet feeding cassette 10 via the sheet conveyance path 11 and the registration roller pair 12 toward the photosensitive drum 5 on which the toner image is formed as described above, and is transferred by the transfer roller 13 (image transfer unit). The toner image formed on the surface of the photosensitive drum 5 is transferred to the sheet. The sheet onto which the toner image has been transferred is separated from the photosensitive drum 5 and conveyed to a fixing unit 14 having a fixing roller pair 14a to fix the toner image. The sheet that has passed through the fixing unit 14 is conveyed to the upper part of the apparatus by the sheet conveying path 15 and is discharged onto the discharge tray 17 from the discharge port 19 via the discharge roller pair 16.

  In such an image forming apparatus, the sheet heated and pressed by the fixing unit 14 may be largely curled (rolled) depending on conditions. FIG. 7A is a perspective view showing a state in which the sheets 2 are stacked on the discharge tray (see FIG. 6), and FIG. 7B is a view as viewed from the direction of the arrow B of one sheet 2. . FIG. 7 shows a state where the left and right side portions 2a of the sheet 2 discharged along the sheet discharge direction (the direction of arrow A in the figure) are particularly curled.

  Since the degree of curling of the sheet 2 varies depending on the roller pressure of the pressure roller of the fixing unit, the curl height h of the left and right side portions 2a is about 30 mm when large. When the sheet is curled locally in this manner, the sheet discharge port is blocked, and the alignment and stackability of the sheet discharged onto the discharge tray are remarkably impaired, and the previously stacked sheet is pushed out in the discharge direction. There was also a risk of falling from the discharge tray.

  Therefore, as disclosed in Patent Documents 1 and 2, conventionally, the sheet pressing member 20 is extended from the upper part of the sheet discharge port 19 substantially vertically downward with respect to the sheet conveying direction to press the curled sheet. Sheet alignment and stackability were improved. As shown in FIG. 8, the sheet pressing member 20 is disposed at two positions on the left and right sides of the sheet discharge port 19, and is configured to press both left and right end portions of the sheet that are particularly likely to curl.

  FIG. 9 is an enlarged cross-sectional view around the sheet pressing member 20. Both ends of the sheet conveyed through the sheet conveying path 15 including the conveying guides 15 a and 15 b are pressed in the direction of the discharge tray 17 by a sheet pressing member 20 extending substantially vertically downward when passing through the sheet discharge port 19. Alignment and loading on the discharge tray 17 are improved.

  By the way, there is a problem that the sheet pressing member 20 is caught inside the sheet discharge port 19 by the reverse rotation of the discharge roller pair 16 when the user performs an erroneous operation or when the discharge roller pair 16 is used as a switchback device at the time of duplex printing. there were. That is, as shown in FIGS. 8 and 9, the discharge roller pair 16 is rotated in a predetermined direction by the driving force transmitted by the shaft 16a, but the sheet discharge port 19 can smoothly discharge the sheet. Since a sufficient clearance is set in a portion where the discharge roller pair 16 does not exist, the sheet pressing member 20 may enter the gap between the shaft 16a and the conveyance guide 15a and be wound around the shaft 16a.

When the sheet pressing member 20 is caught, there is a risk that the sheet pressing member 20 may be damaged or a jam may occur during double-sided printing. Was not taken.
Japanese Patent Laid-Open No. 10-265113 JP 2003-81514 A

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a sheet discharge mechanism that prevents a sheet pressing member from being caught in a sheet discharge port and the occurrence of a jam and the like, and an image forming apparatus including the sheet discharge mechanism, at a low cost. For the purpose.

  In order to achieve the above object, the present invention extends a sheet discharge port, a pair of discharge rollers provided in the vicinity of the sheet discharge port, and substantially vertically downward with respect to the conveying direction at both left and right ends of the sheet discharge port. A sheet pressing member that presses both ends of the sheet passing through the sheet discharge port, and sequentially discharges and stacks the sheets on a discharge tray. The sheet pressing member is formed of a flexible film. The sheet discharge port is characterized in that a convex portion protruding outward from the sheet discharge port is provided on at least a part of the side adjacent to the left and right ends of the sheet discharge port.

  In the sheet discharge mechanism having the above-described configuration, the sheet pressing member includes a pressing portion that contacts the left and right ends of the sheet and presses the sheet downward, and an attachment portion that is fixed to an upper end of the sheet discharge port. Are integrally formed substantially vertically.

  The present invention also provides an image forming apparatus including the sheet discharge mechanism having the above-described configuration.

  According to the first configuration of the present invention, since the convex portions provided on the sheet pressing member are in contact with the wall surfaces at the left and right ends of the sheet discharge port, the tip of the sheet pressing member is temporarily drawn into the sheet discharge port. Even if this occurs, it is possible to prevent the sheet pressing member from being completely caught and damaged, or jamming.

  Further, according to the second configuration of the present invention, in the sheet discharge mechanism of the first configuration, the pressing portion that contacts the left and right ends of the sheet and presses the sheet downward is fixed to the upper end of the sheet discharge port. Since the attachment portion is integrally formed substantially vertically using a flexible film, the sheet pressing member can be produced easily and at low cost. Further, since the pressure of the sheet conveyed from the pair of discharge rollers acts in a direction substantially perpendicular to the attachment portion, the sheet pressing member fixed to the sheet discharge port is difficult to come off.

  In addition, according to the third configuration of the present invention, by mounting the sheet discharge mechanism of the first or second configuration, the sheet pressing member is caught in the sheet discharge port, and the occurrence of a jam or the like is caused. Provided is an easy-to-use image forming apparatus that can be prevented.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external perspective view showing a configuration of an image forming apparatus provided with a sheet discharge mechanism of the present invention. Portions common to FIG. 8 of the conventional example are denoted by the same reference numerals and description thereof is omitted. In FIG. 1, the sheet discharge mechanism includes a discharge roller pair 16, a sheet discharge port 19, and a sheet pressing member 20, and the sheet pressing members 20 provided on the left and right sides of the sheet discharge port 19 (broken line portion in the drawing). Each has a convex portion 21 that protrudes outward from the sheet discharge port 19.

  FIG. 2 is a perspective view of a sheet pressing member used in the present invention. In FIG. 2, the sheet pressing member 20 disposed on the right side toward the sheet discharge port 19 will be described. However, the sheet pressing member 20 disposed on the left side also has a configuration in which the protruding direction of the convex portion 21 is reversed. The configuration is exactly the same. The sheet pressing member 20 is in contact with the left and right side portions 2a (refer to FIG. 7) of the sheet discharged from the sheet discharge port 19 (refer to FIG. 1) and pressed downward, and the double-sided adhesive tape 22 is interposed therebetween. A mounting portion 20b fixed to the upper end of the sheet discharge port 19 is integrally formed. A convex portion 21 for preventing the sheet pressing member 20 from being caught is integrally formed on a part of the right end of the pressing portion 20a.

  The pressing portion 20a and the mounting portion 20b are in a substantially vertical positional relationship, and the pressing force of the sheet conveyed from the discharge roller pair 16 (see FIG. 1) is parallel to the mounting portion 20b, that is, the peeling of the mounting portion 20b. Acts in a direction substantially perpendicular to the direction. For this reason, peeling of the sheet pressing member 20 due to the pressing force of the sheet hardly occurs.

  The material of the sheet pressing member 20 is not particularly limited as long as it is a flexible synthetic resin film or the like, but a film having a strength that can suppress the curling of the sheet is preferable. As such a film, for example, a polyethylene terephthalate (PET) film (Lumirror film) is preferably used. Further, the size and thickness of the sheet pressing member 20 are not particularly limited, and may be set as appropriate depending on the size of the sheet discharge port 19, the size of the conveyed sheet, and the like. You need to have power. Therefore, for example, in the case of a PET film, the thickness of the film is preferably 0.1 mm or more.

  Next, a method for arranging the sheet pressing member will be described. FIG. 3 is an exploded perspective view of the sheet discharge mechanism of the present invention. First, the attachment portion 20b of the sheet pressing member 20 is fixed to the back surface of the exterior cover 24 that constitutes the upper surface of the sheet discharge port with a double-sided adhesive tape 22 (see FIG. 2). Then, the exterior cover 24 to which the sheet pressing member 20 is fixed is attached to the image forming apparatus 1 main body side. At this time, the sheet pressing member 20 is disposed such that the convex portion 21 comes into contact with the wall surfaces 23 at both the left and right ends of the sheet discharge port 19.

  Thereby, even if the leading end of the sheet pressing member 20 enters the inside of the sheet discharge port 19, since the convex portion 21 is in contact with the wall surface 23, the sheet pressing member 20 is further drawn and is wound on the shaft 16a. Can be prevented.

  Further, the size and shape of the convex portion 21 are not particularly limited as long as they can contact the wall surface 23 and prevent the sheet pressing member 20 from being caught. For example, as shown in FIG. It is good also as the shape made to protrude. Alternatively, as shown in FIG. 5, the attachment portion 20 b may not be provided, and a sheet-like film composed of the pressing portion 20 a and the convex portion 21 may be attached to the front surface of the sheet discharge port 19 with the double-sided adhesive tape 22.

  In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the method of fixing the sheet pressing member 20 is not limited to the double-sided adhesive tape 21, and an adhesive or adhesive may be applied to the pressing portion 20a, or may be fixed using screws, rivets, or the like. good. The sheet discharge mechanism of the present invention can be applied to various image forming apparatuses such as analog and digital monochrome copying machines, color copying machines, facsimile machines, and printers.

  The present invention relates to a sheet discharge port, a pair of discharge rollers provided in the vicinity of the sheet discharge port, and a sheet that extends substantially vertically downward with respect to the conveyance direction at the left and right ends of the sheet discharge port and passes through the sheet discharge port. A sheet pressing member that presses both ends, and sequentially discharges and stacks sheets on a discharge tray.The sheet pressing member is formed of a flexible film, and has left and right ends of the sheet discharge port. A convex portion that protrudes outward from the sheet discharge port is provided on at least a part of the adjacent side.

  As a result, even when the sheet pressing member is about to be pulled into the sheet discharge port, the convex portions provided on the sheet pressing member abut against the wall surfaces at the left and right ends of the sheet discharge port. It becomes possible to provide a sheet discharge mechanism that can effectively prevent breakage and jamming.

  In addition, if a pressing part that contacts the left and right ends of the sheet and presses the sheet downward and an attachment part that is fixed to the upper end of the sheet discharge port are integrally formed substantially vertically with a single film, The configuration of the sheet pressing member is simplified, contributing to cost reduction of the sheet discharge mechanism, and suppressing the sheet pressing member from being detached due to the pressure of the discharged sheet.

  Further, if the sheet discharge mechanism of the present invention is installed in an image forming apparatus such as a copying machine or a printer, the image forming apparatus can prevent the sheet pressing member from being caught in the sheet discharge port and the accompanying jamming. .

FIG. 3 is a perspective view of an image forming apparatus equipped with the sheet discharge mechanism of the present invention. These are perspective views which show the structure of the sheet | seat pressing member used for the sheet | seat discharge mechanism of this invention. FIG. 3 is an exploded perspective view of an image forming apparatus equipped with the sheet discharge mechanism of the present invention. These are perspective views which show the other structure of a sheet | seat pressing member. These are perspective views which show the other structure of a sheet | seat pressing member. FIG. 1 is a schematic cross-sectional view showing an overall configuration of a conventional image forming apparatus. These are the perspective view and side view which show the state which the left and right both ends of the sheet | seat curled. FIG. 3 is a perspective view of a conventional image forming apparatus. FIG. 9 is an enlarged cross-sectional view illustrating a configuration around a sheet discharge port in a conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Sheet | seat 16 Discharge roller pair 17 Discharge tray 19 Sheet | seat discharge port 20 Sheet | seat pressing member 20a Holding | suppressing part 20b Mounting part 21 Convex part 22 Double-sided adhesive tape 23 Wall surface 24 Exterior cover

Claims (3)

A sheet discharge port, a discharge roller pair provided in the vicinity of the sheet discharge port, and both ends of the sheet extending substantially vertically downward with respect to the conveying direction at the left and right ends of the sheet discharge port and passing through the sheet discharge port. A sheet pressing mechanism that presses, and sequentially discharges and stacks sheets on a discharge tray.
The sheet pressing member is formed of a flexible film, and a convex portion protruding outward from the sheet discharge port is provided on at least a part of a side adjacent to the left and right ends of the sheet discharge port. Sheet discharge mechanism.   The sheet pressing member is characterized in that a pressing portion that contacts the left and right ends of the sheet and presses the sheet downward and an attachment portion that is fixed to the upper end of the sheet discharge port are integrally formed substantially vertically. The sheet discharge mechanism according to claim 1.   An image forming apparatus comprising the sheet discharge mechanism according to claim 1.

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