JP2006347711A - Sheet feeding device and image forming device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeding device capable of effectively suppressing vibrations of a retard roller even in the case where the axial center of a feed roller and the retard roller, and the movable direction of the retard roller are not in a straight line. <P>SOLUTION: The sheet feeding device 1 has a movable bottom plate 30 for guiding a sheet S loaded inside a main body, a pickup roller 1a for discharging the sheet S loaded on the movable bottom plate 30, and the sheet feeding device 1 having the feed roller 1b and the retard roller 1c for sandwiching the sheet S discharged by the pickup roller 1a, separating it one by one, and conveying it. The device 1 is characterized in that it has a holding member 37 rotatably provided for rotatably supporting the retard roller 1c, an energizing means 41 for energizing the holding member 37 in the rotating direction to pressurize the retard roller 1c to the feed roller 1b, an elastic piece 39 formed at a tip end in the radial direction of the holding member 37, and an arc wall 42 positioned on the outside of the rotating radius of the holding member 37; and that the elastic piece 39 is elastically pressure-welded to the inner side of the arc wall. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet feeding apparatus such as a feeding cassette that feeds a stored sheet, and an image forming apparatus including the sheet feeding apparatus.

  The image forming apparatus includes a sheet feeding device such as a sheet feeding cassette for separating the sheet bundles stacked on the sheet feeding tray one by one and transporting them to the image forming unit.

  In such a sheet feeding apparatus, a retard roller is provided at a position facing the feed roller, and has a configuration that rotates in the same direction. With such a mechanism, when two or more sheets enter the nip portion between the feed roller and the retard roller, only the uppermost sheet is conveyed to the image forming unit, and the second and subsequent sheets are transferred to the retard roller. Is pushed back by not being driven by the feed roller (reversely rotating in the sheet conveying direction). In the case of a single sheet, the retard roller follows the feed roller (rotates in the sheet conveyance direction) to convey the sheet.

  In this way, since the sheet is nipped by the feed roller and the retard roller and conveyed one by one, when the sheet passes through the nip portion of the feed roller and the retard roller, the retard roller vibrates in the vertical direction. In this case, the sheet may be returned to the upstream side in the conveyance direction or noise may be generated.

  As a countermeasure against such a problem, for example, Patent Documents 1 and 2 disclose document feeding including a feed roller, a retard roller, a holding member that holds the feed roller, and a biasing unit that biases the holding member. An apparatus is disclosed.

  First, in Patent Document 1, a pressure spring is used as a biasing means, and a pressure auxiliary member made of an elastic member is provided at a position in contact with the pressure spring and the holding member (bracket). By combining two members having different damping coefficients, retarding roller (separation roller) vibration is absorbed.

On the other hand, in Patent Document 2, vibration preventing means for applying resistance to the side surface of the holding member is provided to suppress vibration of the retard roller (double feed preventing roller).
Japanese Patent Laid-Open No. 9-202477 (see FIG. 1) JP2003-192164A (see FIG. 10)

  However, in the method of combining two members having different damping coefficients of the pressure spring and the pressure assist member as in Patent Document 1, the shaft centers of the feed roller and the retard roller and the movable direction of the retard roller are arranged in a straight line, When the direction in which the separation roller is urged by the urging means is the same direction, a vibration absorbing effect can be expected, but the feed roller and retard roller shaft center and the retard roller shaft center and the movable direction are not in a straight line. Has a problem that it cannot sufficiently absorb the force in the direction of occurrence of vibration.

  Moreover, in the method of pressing down the vibration of the retard roller from the side surface of the holding member as in Patent Document 2, the vertical movement of the retard roller may be hindered. Further, since only one side surface of the holding member is held, the retard roller is inclined, and there is a risk of causing skew during paper feeding.

  Accordingly, an object of the present invention is to provide a sheet feeding device that can effectively suppress vibration of the retard roller even when the shaft center of the feed roller and the retard roller and the movable direction of the retard roller are not in a straight line. .

In order to achieve the above object, the present invention provides a movable bottom plate for guiding a sheet placed in a main body, a pickup roller for feeding out a sheet stacked on the movable bottom plate, and a sheet sent by the pickup roller. In a sheet feeding apparatus having a feed roller and a retard roller that separate and convey one sheet at a time, a holding member that is rotatably provided and rotatably supports the retard roller, and the retard roller is An urging means for urging the holding member in the turning direction so as to press against the feed roller, an elastic piece formed at a distal end portion in the radial direction of the holding member, and an outside of the turning radius of the holding member The elastic piece is elastically pressed against the inner surface of the arc wall.

  Further, since the retard roller rotates around the rotation fulcrum and contacts the feed roller, the elastic piece is provided on the side opposite to the rotation fulcrum of the holding member, thereby efficiently reducing vibration during feeding. it can.

  In addition, the present invention is characterized in that the above-described sheet feeding device is provided in an image forming apparatus.

  According to the present invention, the holding member is always pressed in the rotation center direction, and there is no backlash between the holding member and the main body. Therefore, even when the shaft center of the feed roller and the retard roller and the movable direction of the retard roller are not in a straight line, the elastic piece portion is elastically deformed, thereby suppressing the occurrence of vibration during feeding and suppressing the generation of noise. Can do. In addition, the direction of the force that presses the holding member in the direction of the rotation center is a direction that does not oppose the sheet feeding direction, so that the movement of the holding member is hardly obstructed and smooth feeding operation is performed. It can be carried out.

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

  FIG. 1 is a schematic configuration diagram of an image forming apparatus including a feeding cassette (sheet feeding apparatus) according to the present embodiment. FIG. 2 is a schematic perspective view of the feeding cassette of FIG. In this embodiment, a laser beam printer (hereinafter simply referred to as “printer”) 1 is illustrated as an example of an image forming apparatus. Needless to say, the image forming apparatus can be applied to apparatuses other than a printer, such as a copying machine or a facsimile apparatus.

  First, an outline of the printer 1 will be described. Rollers 4a, 4b, and 4c that convey a sheet S fed from a feeding cassette 2 that can be attached to and detached from the printer 1, and information light D that is based on image information is a photosensitive member that is an electrophotographic photosensitive member of the image forming means 6. The scanner unit 5 for irradiating the drum 6a, the image forming means 6 for forming an image on the photosensitive drum 6a, the transferring means 7 for transferring the image formed on the photosensitive drum 6a to the sheet S, and the transferred image on the sheet S A fixing unit 8 for fixing and a control unit (not shown) are provided.

  The image forming unit 6 includes the above-described photosensitive drum 6 a and at least one process unit, and is unitized as a process cartridge that can be attached to and detached from the printer 1. Examples of the process means include a charging means for charging the photosensitive drum 6a, a developing means for developing a latent image formed on the photosensitive drum 6a, and a cleaning means for cleaning toner remaining on the surface of the photosensitive drum 6a. is there.

  In the printer 1 having such a configuration, the information light D based on the image information is irradiated from the scanner unit 5 to the photosensitive drum 6a, a latent image is formed on the photosensitive drum 6a, and the latent image is developed to develop the photosensitive image. A toner image is formed on the body drum 6a. The printer 1 feeds the sheets S one by one from the feeding cassette 2 by the pick roller 1a in synchronization with the formation of the toner image, and separates and feeds the sheets S one by one by the feed roller 1b and the retard roller 1c. Then, the toner image formed on the photosensitive drum 6 a constituting the image forming unit 6 is transferred onto the sheet S by the transfer unit 7. The transferred sheet S is conveyed to the fixing unit 8 where the transferred toner image is fixed by the fixing unit 8, and is further discharged outside the apparatus by the discharge roller 4c.

  Here, the configuration of the sheet feeding apparatus according to the present embodiment will be specifically described with reference to FIGS.

  As shown in FIG. 2, the feeding cassette 2 is rotatable about a fulcrum 30d between the bottom wall 20, a pair of opposing side walls 21, 22 defining the width of the cassette, and both side walls 21, 22. And a bottom plate 30 on which sheets S (not shown) are stacked. A front panel 23 is provided at the end on the rear end side in the mounting direction of the feeding cassette 2. The front panel 23 is supported by a plurality of rib walls 24 extending rearward from a guide wall 27 provided with a plurality of guide ribs 26 for guiding sheet conveyance.

  An idler gear 32 is rotatably supported on the front outer surface of one side wall 21. The sector gear 33 meshes with the idler gear 32 and is installed at one end of the bottom plate push-up arm 31 that is rotatably supported by the feeding cassette 2. The sector gear 33 and the bottom plate push-up arm 31 have a rotation center. Are the same. The idler gear 32 and the sector gear 33 constitute drive receiving means for moving the bottom plate 30 up and down. A cover 35 covering the drive receiving means is detachably attached to one side wall 21 with screws 36.

  On the other hand, in the printer 1 main body, a stepping motor (not shown) and a transmission gear (not shown) rotatably supported so as to rotate by this drive are arranged, and the above-mentioned feeding cassette When 2 is attached to the printer 1, the idler gear 32 (drive receiving means) and the transmission gear (drive transmission means) are engaged with each other.

  The printer 1 stops driving the stepping motor (not shown) when the uppermost surface of the sheet S (not shown) is pressed against the pick roller 1a.

  Further, a rectangular window 28 is provided at a substantially central portion in the width direction of the guide wall 27, and a space 29 (see FIG. 4) is formed below the window 28. The space 29 has an arc wall 42 located outside the turning radius of the holding member 37. The retard roller 1c is rotatably supported by a cup-shaped holding member 37. The holding member 37 is inserted into a pair of bearing portions 38 formed at one end thereof (downstream end in the sheet conveying direction). The connecting shaft 40 (see FIG. 4) is rotatably supported on the side surface of the space 29.

  A pressure spring 41 is provided on the lower surface of the holding member 37 to urge the holding member 37 counterclockwise. As a result, the upper part of the outer peripheral surface of the retard roller 1c protrudes upward from the guide wall 27 through the window 28, and the retard roller 1c is pressed against the feed roller 1b in the sheet conveyance path.

  A pair of elastic pieces 39 that can be elastically deformed in the direction of the connecting shaft 40 is formed at the radial tip of the holding member 37 (downstream end in the sheet conveying direction). Is elastically pressed against the inner surface of the arc wall 42.

  By doing so, the holding member 37 is always pressed against the connecting shaft 40, and there is no backlash between the holding member 37 and the feeding cassette 2. Accordingly, even when the shaft centers of the feed roller 1b and the retard roller 1c and the movable direction of the retard roller 1c are not in a straight line, the elastic piece portion 39 is elastically deformed, thereby suppressing the occurrence of vibration during paper feeding and feeding. Noise generation at the time can be suppressed. Further, the direction of the force to be pressed against the connecting shaft 40 is a direction that does not oppose the sheet feeding direction, so that the movement of the holding member 37 is hardly obstructed and a smooth paper feeding operation can be performed. it can.

  In the above-described embodiment, the case where the bottom plate push-up arm is rotated by using a drive source such as a stepping motor and drive transmission means such as a gear to push up the bottom plate has been described. In addition, the bottom plate is disposed on the back side of the bottom plate. A simple bottom plate push-up mechanism using a biasing means such as a spring can also be adopted.

  The present invention can be used for an image forming apparatus including a sheet feeding device such as a feeding cassette for feeding sheets and a document feeding device such as an ADF for feeding documents.

FIG. 1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. These are the schematic perspective views which show the state which removed the cover which covers the drive reception means of the feeding cassette which concerns on embodiment of this invention. These are the top view (a) and xx sectional view (b) of the holding member which supported the retard roller. These are the expanded sectional views of the periphery of a retard roller and a feed roller showing at the time of paper feed of a feed cassette concerning an embodiment of the present invention.

Explanation of symbols

1 Printer
1a pick roller
1b feed roller
1c retard roller
1c space retard roller
1c retard roller
2 Feed cassette
20 bottom wall
21 side walls
21, 22 side wall
21, 22 Both side walls
27 guide walls
28 windows
29 spaces
30 bottom plate
37 holding member
38 bearings
39 elastic piece
40 connecting shafts
41 pressure spring
42 arc wall
S sheet

Claims (3)

  A movable bottom plate for guiding sheets placed in the main body, a pickup roller for feeding out the sheets stacked on the movable bottom plate, and a sheet fed by the pickup roller, and separating and conveying the sheets one by one In a sheet feeding apparatus having a feed roller and a retard roller, the holding member is rotatably provided and rotatably supports the retard roller, and the holding member is pressed against the feed roller. An urging means for urging in the rotation direction; an elastic piece formed at a distal end portion in the radial direction of the holding member; and an arc wall located outside the rotation radius of the holding member, A sheet feeding apparatus, wherein an elastic piece is elastically pressed against the inner surface of the arc wall.   The sheet feeding apparatus according to claim 1, wherein the elastic piece is provided on a side opposite to the rotation fulcrum of the holding member.   An image forming apparatus comprising the sheet feeding device according to claim 1.

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