JP4533282B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding apparatus provided in an image forming apparatus such as a copying machine, a laser beam printer, and a facsimile machine.

  2. Description of the Related Art Conventionally, some image forming apparatuses are provided with a paper feed cassette that can supply a large-size sheet with a standard size. Also, in order to supply non-standard size paper that cannot be handled by the paper cassette, or to supply paper of a different size from the paper loaded in the paper cassette with the paper cassette set, Another type is provided with a sheet feeding device (multi-paper feeding device) using a paper feeding tray.

  In general, when such a sheet feeding apparatus is not used, in order to eliminate protrusions such as a paper feed tray from the apparatus main body of the image forming apparatus (hereinafter referred to as the apparatus main body), the open / close cover that also serves as an exterior cover is closed. It is stored in the device body. In use, by opening the opening / closing cover, it is possible to stack sheets with the paper feed tray protruding from the apparatus main body.

  FIG. 4 is a schematic configuration showing the above-described conventional sheet feeding apparatus. FIG. 4A shows a schematic configuration when the sheet feeding open / close cover 101 is closed, and FIG. 4B shows the opened state. Mounted on the opening / closing cover 101 are a middle plate 102 for stacking sheets, a width regulating plate 103 for regulating the position of the stacked sheets in the width direction, and an extension tray 104 for supporting the rear end side of the stacked sheets.

  One end of the support member 105 spanned between the apparatus main body and the opening / closing cover 101 is pivotally supported by the rotation center 105 a on both side walls of the apparatus main body, and the other end is formed on the opening / closing cover 101. A pair of left and right links are configured by being supported by a stopper shaft 105b that is movable along the elongated hole. A rotation shaft 102 a of the intermediate plate 102 is supported by a stopper shaft 105 b of the support member 105.

  In the open state of the opening / closing cover 101, the stopper shaft 105b of the supporting member 105 is brought into contact with and locked to one end portion of the elongated hole of the opening / closing cover 101, so that the supporting member 105, the opening / closing cover 101 and the rotating shaft 102a of the middle plate. The posture and position are determined. When the opening / closing cover 101 is closed, the members constituting the sheet feeding device are accommodated inside the apparatus main body, and are rotated clockwise around the rotation center 101a so as to protrude outside the apparatus main body during use (for example, Patent Document 1).

  FIG. 5 is a schematic diagram of a paper feed roller driving unit for driving the paper feed roller 109. The drive gear 111 is driven so as to rotate counterclockwise in the figure about the shaft 111a. Reference numeral 112 denotes a paper feed gear unit (paper feed control means) for controlling the transmission of rotation to the paper feed roller 109. This paper feed gear unit 112 is fixed to a paper feed shaft 110 to which the paper feed roller 109 is attached. A first paper feed gear 113 and a second paper feed gear 114 rotatably attached to the first paper feed gear 113 within a predetermined phase angle range. In addition, a spring mechanism described later is provided between the first paper feed gear 113 and the second paper feed gear 114. A paper feed cam 108 is attached to the paper feed shaft 110. Further, a tension spring 107 for urging the intermediate plate 102 toward the cam 108 is disposed between the apparatus main body and the intermediate plate 102, and is supplied to the intermediate plate contact portion 102 b provided on the intermediate plate 102. The paper cam 108 is in sliding contact. A separating member 106 urged by a separating pressure spring (not shown) corresponding to the sheet feeding roller 109 is disposed.

  In the sheet feeding apparatus configured as described above, the sheets stacked on the intermediate plate 102 and the extension tray 104 are rotated by the cam 108 according to the rotation of the paper supply roller 109 and the intermediate plate contact portion 102b. And slid. When the cam 108 and the intermediate plate contact portion 102b are separated from each other, the intermediate plate 102 that is rotatable about the rotation center 102a on the apparatus main body is pushed up by the urging force of the tension spring 107, and the stacked sheets are stacked. Is pressed by the paper feed roller 109. The uppermost sheet is guided to the separating member 106 urged by a separating pressure spring (not shown) by the rotating sheet feeding roller 109, and the sheet is separated one by one between the sheet feeding roller 109 and the separating member 106. Sent out.

  When the sheet feeding roller 109 makes one rotation, the cam 108 pushes down the middle plate contact portion 102 b again to separate the sheets stacked on the middle plate 102 from the sheet feeding roller 109.

  Next, the configuration of the spring mechanism and the rotation control by the paper feed gear unit 112 will be described with reference to FIGS. 5 and 6. FIG. 6 is a side view of the drive unit of FIG. For the sake of explanation, a perspective view illustrating the inside of the second paper feed gear 114 is used.

  In the paper feed standby state shown in FIG. 6A, the compression spring 115 is compressed by the spring seat 113c formed on the first paper feed gear 113 and the spring seat 114c formed on the second paper feed gear 114. Yes. Furthermore, the first paper feed gear 113 and the second paper feed gear 114 have a plurality of teeth 113a and 114a and toothless portions 113b and 114b without teeth, respectively. Reference numeral 116 denotes a solenoid provided on the apparatus main body side. A movable piece 117 of the solenoid 116 is locked to a locking portion 114f of a cam 114e formed integrally with the second paper feed gear 114. . Here, the drive gear 111 is always rotating counterclockwise in FIG. The second paper feed gear 114 is given a moment that rotates in the clockwise direction by the elastic force of the compression spring 115.

  When the solenoid 116 is in the OFF state, the claw of the movable piece 117 is locked to the locking portion 114f as shown in FIG. 6A, so that the state shown in FIG. The tooth portion 114 b stops at a position facing the drive gear 111. At this time, the first paper feed gear 113 is also stopped at the position where the toothless portion 113 b faces the drive gear 111. Therefore, the drive gear 111 and the paper feed gear unit 112 are in a non-meshing state, so that even if the drive gear 111 rotates, the rotation is not transmitted to the paper feed gear unit 112.

  On the other hand, when a voltage is applied to the solenoid 116 and the solenoid 116 is turned on, the movable piece 117 moves to the position shown in FIG. 6B, and the claw is disengaged from the locking portion 114 f of the second paper feed gear 114. As a result, the second paper feed gear 114 rotates clockwise by the elastic force of the compression spring 115, and the teeth 114a and the drive gear 111 located downstream in the rotational direction of the missing tooth portion 114b of the second paper feed gear 114 are connected. It becomes a meshing state. Thereafter, the second paper feed gear 114 is driven by the drive gear 111 to rotate by a predetermined phase angle, and accordingly, the rib surface 114d formed on the second paper feed gear 114, and the first paper feed gear 114 The rib surface 113d formed on 113 abuts. By this contact, the paper feed gear unit 112 starts to rotate with the teeth 113a of the first paper feed gear 113 and the teeth 114a of the second paper feed gear 114 in the same phase. Then, the rotation is transmitted to the sheet feeding shaft 110, and the sheet feeding roller 109 starts to rotate and feeds the sheet.

  In this way, by using two paper feed gears each having a toothless portion, the elastic force of the compression spring 115 is weak when the movable piece 117 of the solenoid 116 is moved to remove the claw from the locking portion 114f. Therefore, the solenoid 116 can be downsized and the control can be stabilized.

Next, a state in which the open / close cover is closed will be described with reference to FIGS. 7 (a) and 7 (b). The first paper feed gear 113 is given a moment that rotates counterclockwise by the elastic force of the compression spring 115 shown in FIG. Therefore, the engagement portion 119 between the drive gear 111 and the teeth 113a of the first paper feed gear 113 prevents the teeth 113a and the drive gear 111 from meshing and is provided on the intermediate plate 102 in order to keep the paper feed gear unit 112 at the standby position. The middle plate contact 102 c is in contact with the paper feed cam 108 to restrict the rotation of the first paper feed gear 113.
JP-A-11-189338

  However, in the above-described configuration, when the opening / closing cover 101 is closed, the claw of the movable piece of the solenoid 116 is not detached from the locking portion 114f, or the paper feed roller 109 is not positioned at the initial position due to jam processing or the like. There is. In this case, the drive gear 111 and the paper feed gear unit 112 are in mesh with each other, and if the paper feed roller 109 is rotated back to the initial position to return to the initial state, the paper feed cam 108 also rotates. Resulting in.

  At this time, as shown in FIG. 7B, the locus of the cam surface 108a of the sheet feeding cam 108 is a line 121 indicated by a two-point difference line, and is in contact with the cam 108 at the position of the intermediate plate contact portion 102c. The plate 102 is pushed by the cam 108 through the intermediate plate contact 102c, and moves to the position of the intermediate plate 102 (X) indicated by a broken line.

  Therefore, it is necessary for the sheet feeding apparatus to secure a space for the movement of the intermediate plate 102 in advance, which results in an increase in the main body size. This is because the larger the number of loaded sheets and the larger the outer shape of the cam, the larger the movable range of the intermediate plate 102 in such a case, leading to a larger size.

  The present invention has been made to solve the above problem, and provides a compact feeding device and a compact image forming apparatus by minimizing the movable range of the intermediate plate in a state where the open / close cover is closed. There is.

  In order to achieve the above object, the present invention provides a sheet feeding means for feeding a sheet, a sheet feeding control means for controlling transmission of rotation to the sheet feeding means, and coaxial with the sheet feeding means. A first cam surface that can be interlocked with the sheet feeding means, a second cam surface that is coaxially arranged with the sheet feeding means and that can be interlocked with the sheet feeding means, and an apparatus body. A pressing means for pressing the sheet to be fed supported against the sheet feeding means, and an opening / closing mechanism that opens and closes the opening of the apparatus main body, and enables loading of the sheet when the opening is opened. A cover, wherein the second cam surface is located on the inner side of the first cam surface, and the pressing member is in contact with the first cam surface with the opening / closing cover open, The pressing member abuts on the second cam surface with the opening / closing cover closed. I am characterized in.

  As described above, according to the present invention, it is possible to provide a compact feeding device and a compact image forming apparatus by minimizing the movable range of the intermediate plate in a state where the open / close cover is closed. It becomes.

  First, an image forming apparatus that forms an image on a sheet fed by the sheet feeding apparatus of the present invention will be described. A laser beam printer (image forming apparatus) 1 using an electrophotographic process is configured as shown in FIG. A schematic configuration will be described along the flow of sheets (hereinafter referred to as sheets).

  In FIG. 3, a sheet feeding cassette 5 that can supply a large-capacity sheet of a standard size is provided below the main body of the image forming apparatus. The sheet feeding cassette 5 separates and feeds the stored sheets one by one by a sheet feeding roller 6a and a separating member 6b. Further, the sheet feeding device of the present invention is arranged on the side surface of the device.

  The laser beam printer 1 integrally includes a photosensitive drum 2 on which a latent image is formed by a laser scanner scanning optical system 4, a developing unit (not shown) that forms a toner image on the photosensitive drum 2, a cleaner (not shown), and the like. A process cartridge 3 is provided. The photosensitive drum 2 and a developing device (not shown) constitute an image forming unit 31.

  A sheet feeding roller 109 as a sheet feeding means of the present invention from a sheet P or a sheet feeding tray 101 of a sheet feeding apparatus separated and fed one by one by a sheet feeding roller 6a and a separating member 6b of the sheet feeding cassette 5; The sheets P separated and fed one by one by the separating member 106 are sent to the registration roller pair 8. After being conveyed by the registration roller pair 8, the toner image on the photosensitive drum 2 is transferred by the transfer roller 9. Thereafter, the sheet P is heated and pressed by the fixing device 10 to fix the toner image. The sheet discharge lower roller 11 rotates counterclockwise, and cooperates with the sheet discharge lower roller 12 in contact with the sheet discharge lower roller 11 to convey the sheet P to the sheet discharge upper roller 13. When an image is formed only on one side of the sheet, the image-formed sheet P is discharged onto the sheet discharge tray 14 by the sheet discharge upper roller 13.

  When images are formed on both sides of the sheet, when the trailing edge of the sheet P passes through the sheet discharge lower roller 11, the sheet discharge upper roller 13 rotates in the clockwise direction. The sheet P is sent to the sheet discharge lower roller 11 and the double-sided roller 15 that are in pressure contact with each other, and is sent to the double-sided conveyance path 16. At this time, the portion of the sheet P that has been the leading end becomes the trailing end, and the portion that has been the trailing end becomes the leading end, and is supplied to the photosensitive drum 2 by being turned over.

  Then, the sheet P is conveyed straight with the skew correction corrected by the sheet lateral registration roller pair 17 and the sheet lateral registration correction guide 18, and the position in the width direction is positioned and conveyed. Thereafter, the sheet P is fed between the photosensitive drum 2 and the transfer roller 9 in a state where the front and back are reversed by the double-sided conveyance roller pair 19.

  In the image forming unit 31, the toner image is transferred from the photosensitive drum 2 to the second surface of the sheet P, passes through the fixing device 10, and is discharged to the sheet discharge tray 14 by the sheet discharge upper roller 13. As a result, the sheet P is discharged to the sheet discharge tray 14 with images formed on both sides.

  An embodiment of the present invention will be described with reference to FIGS. 1 (a) and 1 (b). In addition, about the structure similar to a prior art, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the state where the opening / closing cover is opened, the first cam surface 108a of the cam 108 and the middle plate contact portion 102b are in contact with each other as in the description with reference to FIG. As the sheet rotates, the middle plate 102 moves up and down to repeat the sheet feeding operation and separate and feed the sheets. Note that the pressing means of the present invention includes the intermediate plate 102 and the tension spring 107.

  A side surface of the cam 108 is integrally provided with a second cam surface 108b that is coaxially different from the first cam surface 108a. The position of the second cam surface 108b is disposed on the inner side (position close to the paper feed shaft 110) than the first cam surface 108a for pushing down the intermediate plate 102. That is, the outer diameter of the second cam surface 108b is set smaller than the outer diameter of the first cam surface 108a. The middle plate contact portion 102b provided on the middle plate 102 can be slidably contacted with the first cam surface 108a, and the middle plate contactor provided on the middle plate 102 on the second cam surface 108b. 102d is slidable.

  When the open / close cover 101 is closed, the second cam surface 108b and the middle plate contact 102d of the middle plate 102 come into contact with each other to restrict the rotation of the paper feed shaft 110 and the first paper feed gear 113. Thus, the meshing portion 119 between the drive gear 111 and the teeth 113a of the first paper feed gear 113 can prevent the teeth 113a and the drive gear 111 from meshing, and the paper feed gear unit 112 can be kept in the standby position. Accordingly, the drive gear 111 and the paper feed gear unit 112 are brought into a non-meshing state, so that even if the drive gear 111 rotates, the rotation is not transmitted to the paper feed gear unit 112.

  However, when the claw of the movable piece of the solenoid 116 is disengaged from the locking portion 114f with the open / close cover 101 closed, or when the paper feed roller 109 is not positioned at the initial position due to jam processing or the like. The drive gear 111 and the paper feed gear unit 112 are sometimes kept in mesh. In this state, since the drive gear 111 is always rotating, the rotation is transmitted to the sheet feeding shaft 110 via the second sheet feeding gear 114 and the first sheet feeding gear 113, and the sheet feeding roller 109 returns to the initial position. Is rotated. At this time, the sheet feeding cam 108 also rotates, but the locus of the second cam surface 108b of the sheet feeding cam 108 is a line 122 indicated by a two-dot chain line, and the second cam surface 108b and the middle plate contactor 102d Even if the middle plate 102 in contact with the position is pushed by the cam 108, the middle plate 102 moves only to the position of the middle plate 102 (Y) indicated by a broken line.

  That is, since the intermediate plate contact 102d is regulated by the second cam surface 108b provided separately from the first cam surface 108a for moving the intermediate plate 102, the first cam surface 108a is provided as in the prior art. The middle plate 102 is not greatly pushed down to the position of the two-dot chain line 121 by the middle plate contact 102d. Therefore, the enlargement of the apparatus can be prevented.

  2A and 2B are modifications of the above embodiment. In addition, about the structure similar to the said embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. The operation with the open / close cover open is the same as in the above embodiment.

  This modification is characterized in that a recess 108c is provided on the second cam surface 108b of the above embodiment. The position of the recess 108 c is formed so that the middle plate contact 102 d of the middle plate 102 is fitted in the standby position of the paper feed roller 109. Then, at the standby position of the first paper feed gear 113, the middle plate contact 102d of the middle plate 102 is fitted in the recess 108c of the second cam surface 108b, and the second cam surface is moved from the middle plate contact 102d. A moment toward substantially the center of rotation is given to 108b. That is, a contact shape that does not apply a rotational force to the first paper feed gear 113 by the indented portion 108 c is configured.

  With this configuration, it is possible to avoid applying an excessive rotational force to the second paper feed gear 114 and to avoid an increase in the cost of the solenoid due to the suction force UP of the solenoid 116.

  When the claw of the movable piece of the solenoid 116 is disengaged from the engaging portion 114f, or when the paper feed roller 109 is not positioned at the initial position due to jam processing or the like, the drive gear 111 and the paper feed gear unit 112 are The meshing state may be maintained. In this state, since the drive gear 111 is always rotating, the rotation is transmitted to the sheet feeding shaft 110 via the second sheet feeding gear 114 and the first sheet feeding gear 113, and the sheet feeding roller 109 returns to the initial position. Rotation is performed. The paper feed cam 108 also rotates. At this time, the sheet feeding cam 108 also rotates. However, the locus of the second cam surface 108b of the sheet feeding cam 108 is a line 122 indicated by a two-dot chain line, and the second cam surface 108b and the middle plate contactor 102d meet. The contacting intermediate plate 102 is pushed by the cam 108 and moves only to the position of the intermediate plate 102 (Z) indicated by a broken line. Then, the middle plate contact 102d fits into the recess 108c and stops rotating, and the drive gear 111 and the paper feed gear unit 112 are brought into a non-engagement state. As a result, even if the drive gear 111 rotates, the standby state is reached in which the rotation is not transmitted to the paper feed gear unit 112.

  As described above in detail, in the present embodiment, when the opening / closing cover 101 is closed and the paper feed roller 109 is not positioned at the initial position, the middle plate is rotated when returning to the initial position. 102 is not moved greatly. That is, the cam surface with which the contact 102d provided on the intermediate plate 102 abuts in order to hold the paper feed roller 109 at the initial position is different from the first cam surface 108a that moves the intermediate plate 102 instead of the conventional one. The second cam surface 108b is provided. By disposing the second cam surface 108b on the inner side (position close to the paper feed shaft 110) than the first cam surface 108a, the moving amount of the intermediate plate 102 is reduced.

  With this configuration, it is possible to suppress the increase in size of the image forming apparatus as in the past.

  Note that the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the two sheet-feeding gears 113 and 114 provided with the missing tooth portions 113b and 114b are used. The present invention may be applied to a system in which one paper feeding gear provided with a tooth portion is controlled by a solenoid.

  Furthermore, in the above embodiment, the first cam surface 108a and the second cam surface 108b are integrally provided on the paper feed cam 108, but the first cam surface 108a and the second cam surface 108b are separately provided. These cams may be provided respectively, and each cam may be fixed to the paper feed shaft.

  In the above embodiment, the recess 108c is provided on the second cam surface 108b so that the intermediate plate contact 102d fits in the intermediate plate 102. However, the recess is provided on the intermediate plate contact, The second cam surface may be provided with a protruding portion.

1 is a schematic perspective view and a cross-sectional view showing an embodiment of a sheet feeding apparatus according to the present invention. Schematic sectional view and sectional view showing a modification of the sheet feeding apparatus shown in FIG. Sectional drawing which shows an example of the image forming apparatus which mounted | wore with the sheet feeding apparatus shown in FIG. Sectional drawing which shows the open / closed state of an example of the conventional sheet feeding apparatus The perspective view which shows the drive part of the sheet feeding apparatus shown in FIG. Sectional drawing which shows operation | movement of the drive part of the sheet feeding apparatus shown in FIG. Schematic perspective view and sectional view for explaining the problems of the conventional sheet feeding apparatus

Explanation of symbols

108 Feeding cam 108a First cam surface 108b Second cam surface 102 Middle plate 102b Middle plate contact portion 102d Middle plate contact 107 Tension spring 109 Feed roller 111 Drive gear 112 Feed gear unit

Claims (7)

Sheet feeding means for feeding sheets;
A sheet feeding control means for controlling transmission of rotation to the sheet feeding means;
A first cam surface disposed coaxially with the sheet feeding means and capable of interlocking with the sheet feeding means;
A second cam surface arranged coaxially with the sheet feeding means and interlockable with the sheet feeding means;
A pressing unit that is swingably supported by the apparatus main body and presses the sheet to be fed against the sheet feeding unit;
An opening and closing cover that opens and closes the opening of the apparatus main body, and enables loading of a sheet when the opening is opened;
Have
The second cam surface is located on the inner side of the first cam surface, the pressing member is in contact with the first cam surface with the opening / closing cover open, and the opening / closing cover is closed. The sheet feeding device, wherein the pressing member is in contact with the second cam surface.   The first cam surface is arranged for swinging the pressing means, and the second cam surface is for restricting rotation of the sheet feeding means when the opening / closing cover is closed. The sheet feeding device according to claim 1, wherein the sheet feeding device is arranged.   3. The sheet feeding device according to claim 1, wherein an outer diameter of the second cam surface is smaller than an outer diameter of the first cam surface. 4.   By disposing the opening / closing cover in the initial state of the sheet feeding means so that a moment from the pressing member toward the substantial rotation center of the second cam is applied to the second cam. The sheet feeding apparatus according to any one of claims 1 to 3, wherein the sheet feeding device has a force relationship that does not apply a rotational force to the second cam.   The first and second cam surfaces are formed as a single cam, and the cam is disposed coaxially with the sheet feeding means. The sheet feeding apparatus according to claim 1. The paper feed control means includes a drive gear connected to a drive source,
A first sheet feeding gear connected to the sheet feeding means, provided so as to be able to mesh with the drive gear, and having a toothless portion;
A second paper feed gear disposed coaxially with the first paper feed gear and having a toothless portion;
A spring disposed between the first paper feed gear and the second paper feed gear;
A solenoid for restricting rotation of the second paper feed gear;
The second feed gear is rotated by the spring and meshed with the drive gear, and then the first feed gear is rotated and meshed with the drive gear. The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device. The sheet feeding device according to any one of claims 1 to 6,
Image forming means for forming an image on the sheet fed from the sheet feeding device;
An image forming apparatus comprising:

Images