JP2013124175A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus including a paper sheet feeder that successively feeds sheets from a sheet bundle one by one, and also achieves miniaturization of the image forming apparatus in width.SOLUTION: The image forming apparatus 100 includes a paper sheet feeding cassette 10, a paper sheet feeding roller 14, and a separation pawl 16. An image forming portion 30 and a sheet conveying path 20 for conveying the sheet P1 to the image forming portion 30 are arranged at a position upper than a paper sheet feeding cassette body 11 within a range of width occupied by the paper sheet feeding cassette body 11 in a sheet feeding direction. The tip of the separation pawl 16 is arranged between the front end 11T and the rear end 11E of the paper sheet feeding cassette body 11. The paper sheet feeding roller 14 is arranged at a position nearer to the side of the rear end 11E from the tip of the separation pawl 16 between the front end 11T and the rear end 11E of the paper sheet feeding cassette body 11.

Description

  The present invention relates to an image forming apparatus. More specifically, the present invention relates to an image forming apparatus including a sheet feeding device that separates sheets from a sheet bundle one by one and conveys them to an image forming unit.

  Some image forming apparatuses include an image forming unit for forming an image on a sheet and a sheet feeding device for feeding a sheet conveyed to the image forming unit. In order to supply sheets one by one from a sheet bundle, a sheet feeding device is often provided with a separation mechanism for separating sheets.

  For example, in Patent Document 1, after the separation roller rotates in reverse (see arrow Tb in FIG. 1 of Patent Document 1), the separation roller rotates in a normal direction (see arrow Ta in FIG. 1 of Patent Document 1). A paper feeding device for feeding out the paper is disclosed. Thereby, the uppermost sheet is separated from the sheet bundle, and the sheet can be conveyed to the sheet conveyance path. Patent Document 2 discloses a paper feeding device having an auxiliary roller that rotates forward after reverse rotation (see FIG. 2 of Patent Document 2). Thus, it is possible to prevent double feeding of sheets.

JP-A-3-51230 JP 2002-87606 A

  In recent years, there has been a demand for downsizing image forming apparatuses. This is to respond to environmental problems and save space in the office. However, as shown in FIG. 1, the width of the conventional image forming apparatus includes the width of the sheet feeding cassette (see arrow A in FIG. 1) and the width of the portion that accommodates the sheet conveyance path (see arrow B in FIG. 1). And the total width (width of arrow A + B in FIG. 1). Therefore, the size in the width direction of the image forming apparatus has a lower limit of this width (A + B). The same applies to the paper feeding apparatuses described in Patent Document 1 and Patent Document 2.

  The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide an image forming apparatus including a sheet feeding device that sequentially feeds sheets one by one from a sheet bundle and that reduces the width of the image forming apparatus.

  In order to solve this problem, an image forming apparatus according to an aspect of the present invention includes a sheet feeding cassette that accommodates a sheet bundle, and a separation member that separates the sheet from the sheet bundle accommodated in the sheet feeding cassette. A sheet feed roller that feeds the uppermost sheet from a sheet bundle stored in the sheet feed cassette, an image forming unit that forms an image on the sheet fed from the sheet feed cassette, and a space between the sheet feed cassette and the image forming unit. And a sheet conveyance path positioned. The image forming unit and the sheet conveyance path are disposed at a position within the width from the front end to the rear end in the sheet feeding direction of the sheet feeding cassette and above the sheet feeding cassette. Is disposed at a position between the front end and the rear end of the paper feed cassette, and the paper feed roller is located between the front end and the rear end of the paper feed cassette and from the position of the front end of the separation member. It is arranged at a position close to the rear end side of the paper cassette. In such an image forming apparatus, there is no significant difference between the entire width of the image forming apparatus and the width of the paper feed cassette. That is, the image forming apparatus is downsized.

  In the image forming apparatus described above, a control unit that causes the paper feed roller to perform a reverse rotation that feeds the uppermost sheet of the sheet bundle in the reverse direction of the sheet conveyance path, and then forwards the sheet in the direction of the sheet conveyance path It is good to have. This is because the uppermost sheet can be suitably sent out from the sheet bundle.

  In the image forming apparatus described above, the reverse rotation amount of the sheet feeding roller by the control unit may be a rotation amount that moves the leading end of the sheet to a position between the leading end of the separation member and the feeding roller. . This is because the sheets can be conveyed backward one by one while the sheets are temporarily retracted and suitably separated from the sheet bundle.

  In the image forming apparatus described above, the sheet feeding cassette may have a bent or curved push-up plate on which the sheet bundle is placed in a convexly curved state. This is because it is easy to separate the uppermost sheet from the sheet bundle.

  In the image forming apparatus described above, the paper feed cassette may be provided with an inclined surface in a direction that widens away from the bottom plate of the paper feed cassette at the rear end of the paper feed cassette. This is because it is possible to prevent the sheet from being temporarily retracted from being folded.

  In the image forming apparatus described above, the inclined surface may be formed of a high friction member. This is because separation of the sheets can be suitably performed.

  According to the present invention, there is provided an image forming apparatus including a sheet feeding device that sequentially feeds sheets one by one from a sheet bundle and that has a reduced width of the image forming apparatus.

It is a schematic block diagram for demonstrating the conventional image forming apparatus. 1 is a schematic configuration diagram for explaining an image forming apparatus according to an embodiment. It is a schematic block diagram for demonstrating the paper feed cassette which concerns on embodiment. It is a figure for demonstrating the conveyance roller and separation nail | claw which concern on embodiment. FIG. 6 is a diagram (No. 1) for describing a sheet feeding operation of the image forming apparatus according to the embodiment. FIG. 10 is a second diagram illustrating a sheet feeding operation of the image forming apparatus according to the embodiment. FIG. 10 is a third diagram illustrating a sheet feeding operation of the image forming apparatus according to the embodiment. It is a figure explaining the case where many sheets are mounted in the paper feed cassette concerning an embodiment. FIG. 10 is a diagram illustrating a case where only one sheet is placed on the sheet feed cassette according to the embodiment. It is a schematic block diagram (the 1) for demonstrating the paper feed cassette which concerns on a modification. It is a schematic block diagram (the 2) for demonstrating the paper feed cassette which concerns on a modification. FIG. 10 is a schematic configuration diagram (No. 3) for explaining a paper feed cassette according to a modified example.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. This embodiment embodies the present invention for a monochrome printer.

1. Image Forming Apparatus The image forming apparatus 100 is a monochrome printer as shown in a schematic configuration in FIG. The image forming apparatus 100 includes a paper feed cassette 10, a paper feed roller 14, a sheet conveyance path 20, an image forming unit 30, a transfer roller 40, a fixing device 50, a paper discharge roller pair 61, and a paper discharge tray. 62, a motor M, and a control unit 100.

  The paper feed cassette 10 accommodates a sheet bundle and sends out the uppermost sheet from the sheet bundle. The fed sheet is conveyed toward the image forming unit 30 via the sheet conveyance path 20. Details of the configuration will be described later. The paper feed cassette 10 can also be pulled out from the image forming apparatus 100 toward the front in FIG. In the description of this embodiment, the horizontal direction in FIG. 2 in the image forming apparatus 100 is referred to as the width direction. The maximum dimension in the width direction of the image forming apparatus 100 is referred to as “full width W”. Further, the length from the front end to the rear end in the sheet feeding direction of the sheet cassette 10 is referred to as “width W1”.

  The paper feed roller 14 feeds the uppermost sheet from the sheet bundle of the paper feed cassette 10 and sends it to the sheet conveyance path 20. The sheet conveyance path 20 is for conveying the sheet fed from the sheet feeding cassette 10 toward the image forming unit 30. The sheet conveyance path 20 is provided with a timing sensor 21 for measuring the timing at which the sheet is sent to the transfer roller 40. The sheet conveyance path 20 is disposed at a position within the range of the width W1 of the paper feed cassette 10 and above the paper feed cassette 10. Accordingly, the overall width W of the image forming apparatus 100 of the present embodiment is not so different from the width W1 of the paper feed cassette 10. That is, the size of the image forming apparatus 100 of this embodiment is smaller than that of the conventional image forming apparatus.

  The image forming unit 30 is for forming an image on a sheet. The image forming unit 30 includes a photosensitive drum 31, a charging device 32, an exposure device 33, a developing device 34, and a cleaner 35. The photosensitive drum 31 is an image carrier for carrying a toner image. Therefore, it rotates in the direction of arrow D2 in FIG. The charging device 32 is for charging the surface of the photosensitive drum 31 uniformly. The exposure device 33 is for writing an electrostatic latent image on the surface of the photosensitive drum 31. The developing device 34 is for applying toner to the electrostatic latent image on the photosensitive drum 31 for development. The cleaner 35 is for removing the transfer residual toner on the photosensitive drum 31.

  The transfer roller 40 is a transfer member for transferring a toner image formed on the photosensitive drum 31 to a sheet. The sheet after the toner image is transferred is conveyed in the direction of arrow D1 in FIG.

  The fixing device 50 is for fixing the toner image transferred to the sheet to the sheet. The paper discharge roller pair 61 is for discharging the sheet on which the toner image has been fixed to the paper discharge tray 62. The paper discharge tray 62 is a tray for discharging the fixed sheets.

  The motor M is a drive source for rotationally driving the photosensitive drum 31 and various rollers. The paper feed roller 14 and a later-described transport roller 17 are also objects to be driven by the motor M. Each part such as the photosensitive drum 31 is driven by the motor M. These parts rotate in synchronization with the rotation of the motor M, although the rotation speeds are not necessarily equal to each other by using a reduction gear or the like. The control unit 90 controls the operation of each unit of the image forming unit 30 and the rotation of the motor M.

  As shown in FIG. 2, the image forming unit 30 and the sheet conveyance path 20 are disposed at a position within the range of the width W <b> 1 of the paper feed cassette 10 in the image forming apparatus 100 and above the paper feed cassette 10.

2. Paper feeding device 2-1. Next, the configuration of the paper feed cassette 10 will be described. FIG. 3 is a schematic configuration diagram for explaining the paper feed cassette 10 of the present embodiment. The paper feed cassette 10 is for separating the uppermost sheet P1 from the sheet bundle P and sequentially feeding it one by one to the sheet conveyance path 20. Here, the end on the side of the sheet P1 when the sheet is conveyed to the image forming unit 30 is referred to as a leading end PT. The end portion on the side that becomes the rear end of the sheet P1 when conveyed to the image forming unit 30 is referred to as a rear end PE. As shown in FIG. 3, the paper feed cassette 10 has a paper feed cassette body 11, a push-up spring 12, and a push-up plate 13.

  The paper feed cassette body 11 is a paper feed case for storing the sheet bundle P. The paper feed cassette body 11 includes a bottom plate 11a, a front end portion 11T, and a rear end portion 11E. The front end portion 11T is a side plate of the paper feed cassette main body 11 on the side facing the leading end PT of the sheet P1 before conveyance (when placed). The rear end portion 11E is a side plate of the sheet cassette main body 11 on the side facing the rear end PE of the sheet P1 before conveyance (when placed).

  In addition, an inclined surface 11 b is provided at the rear end portion 11 </ b> E of the paper feed cassette body 11. The inclined surface 11b is inclined so as to expand as the distance from the bottom plate 11a of the sheet feeding cassette body 11 increases. As will be described later, the inclined surface 11b serves as a guide for bending the sheet P1 retracted by the paper feed roller 14 upward from the paper feed cassette 10. The push-up spring 12 is for pushing up the tip PT side of the sheet bundle P upward through the push-up plate 13. The push-up plate 13 is a sheet placement portion for actually placing the sheet bundle P.

2-2. In addition to the paper feed cassette 10, the paper feed roller and the guide member 15 include a paper feed roller 14 and a guide member 15. The paper feed roller 14 and the guide member 15 are not drawable together with the paper feed cassette 10, but are provided in the main body of the image forming apparatus 100. The paper feed roller 14 is disposed at a position downstream of the guide member 15 and a separation claw 16 described later in the sheet conveyance path. The paper feed roller 14 is located between the front end portion 11T and the rear end portion 11E of the paper feed cassette main body 11 and slightly away from the front end position of the separation claw 16 toward the rear end portion 11E side. Has been placed. Under the control of the control unit 90, the paper feed roller 14 rotates in the forward direction (the direction indicated by the arrow DN in FIG. 3) in which the sheet P1 is fed out to the sheet conveyance path 20, and in the direction in which the sheet P1 is sent back from the sheet conveyance path 20. Rotating reverse rotation (direction of arrow DR in FIG. 3) can be performed.

  The guide member 15 is a member for guiding the conveyance of the sheet P1. The guide member 15 includes a separation claw 16 and a conveyance roller 17. The separation claw 16 is a separation member for peeling the sheet P1 from the sheet bundle P and separating it. The front end of the separation claw 16 is disposed at a position between the front end portion 11T and the rear end portion 11E of the paper feed cassette body 11. The transport roller 17 is for transporting the sheet P <b> 1 fed by the paper feed roller 14 to the sheet transport path 20.

  The guide member 15 is provided with a pressure spring 18. The pressure spring 18 pulls the guide member 15. Thereby, the leading end of the separation claw 16 is pressed against the sheet bundle P in the thickness direction. This is because, if the separation claw 16 does not press the sheet bundle P, the leading end PT of the sheet P1 retreated by the paper feed roller 14 as described later may enter the lower side of the separation claw 16. In FIG. 4 and subsequent drawings, the pressure contact spring 18 is omitted.

2-3. Configuration of Guide Member FIG. 4 shows the configuration of the guide member 15 of this embodiment. As shown in FIG. 4, the separation claw 16 and the transport roller 17 are configured integrally with the guide member 15. The separation claw 16 presses the sheet bundle P. Further, if the paper feed roller 14 overlaps and feeds two sheets at a time, it is also a double feed prevention member for feeding only the uppermost sheet P1 to the sheet transport path 20. In this embodiment, as shown in FIG. 4, the separation claw 16 and the transport roller 17 are configured integrally with the guide member 15. However, these may be separate bodies, of course.

  The guide member 15 and the separation claw 16 are resin films such as a polyester film and a polyethylene film. Further, a stainless sheet or a sheet made of steel may be used. Further, the separation claw 16 may be made of a material having a higher friction coefficient or a surface finished in a shape having a higher friction coefficient. This is because the separation of the sheet P1 from the sheet bundle P becomes easier.

3. Next, a paper feeding operation in the paper feeding device will be described. First, as shown in FIG. 5, the paper feed roller 14 rotates (reversely rotates) in the direction of the arrow DR in FIG. The amount of rotation that the paper feed roller 14 rotates in reverse may be determined in advance. However, the reverse rotation amount is a rotation amount by which the leading end PT of the sheet P1 is moved within a range up to a position between the leading end of the separation claw 16 and the sheet feeding roller 14. In other words, it is necessary that the sheet P1 is released from the separation claw 16 and not released from the paper feed roller 14. By the reverse rotation of the sheet feeding roller 14, the uppermost sheet P1 is fed out from the sheet bundle P in a direction away from the sheet conveying path 20. As a result, the sheet P1 is substantially separated from the sheet bundle. Then, the rear end PE of the sheet P1 hits the inclined surface 11b and is turned up. At this time, the transport roller 17 is not rotating.

  Next, the paper feed roller 14 rotates (forward rotation) in the direction of the arrow DN in FIG. Therefore, the uppermost sheet P1 is sent out toward the sheet conveyance path 20. Therefore, the sheet P1 is separated from the sheet bundle P by the separation claw 16 and is sent out toward the sheet conveyance path 20. Then, at the timing when the leading end PT of the sheet P1 rides on the separation claw 16, the conveying roller 17 starts to rotate in the direction of the arrow D3 in FIG.

  Then, as shown in FIG. 7, when the leading end PT of the sheet P <b> 1 passes through the position of the conveyance roller 17, the sheet P <b> 1 is conveyed to the sheet conveyance path 20 by the conveyance roller 17 and the paper feed roller 14. At this time, the paper feed roller 14 is rotated in the direction of the arrow DN (forward rotation) in FIG. 7, and the transport roller 17 is rotated in the direction of the arrow D3 in FIG. Then, when the leading end PT of the sheet P1 reaches the position of the timing sensor 21, the conveyance of the sheet P1 is temporarily stopped. Then, in synchronization with the image formation timing of the photosensitive drum 31, the transport roller 17 and the paper feed roller 14 send out the sheet P <b> 1 toward the transfer roller 40. Thereafter, the toner image is transferred to the sheet P1 by the transfer roller 40.

4). Sheet stacking amount The number of sheet bundles P stacked in the sheet feeding cassette 10 decreases each time an image is formed. Therefore, the difference in the angle of the separation claw 16 depending on the sheet stacking amount of the sheet feeding cassette 10 will be described.

4-1. Full State FIG. 8 shows a case where the stacking amount of the sheet bundle P is the upper limit. In this case, the push-up spring 12 is sufficiently contracted by the weight of the sheet bundle P. Therefore, the angle θA of the push-up plate 13 with respect to the bottom plate 11a is not so large. At this time, the angle between the upper surface of the sheet bundle P and the separation claw 16 is θ1.

4-2. Empty State A case where only one sheet P1 is stored in the sheet feeding cassette 10 will be described with reference to FIG. In this case, the push-up spring 12 is almost fully extended. At this time, the angle θB of the push-up plate 13 with respect to the bottom plate 11a is larger than the angle θA of the push-up plate 13 with respect to the bottom plate 11a in the full state. Even in this case, there is a pressing action of the separation claw 16. However, since there is no sheet bundle P in this case, the separation claw 16 is in pressure contact with the pressing plate 13. The angle θ2 between the upper surface of the sheet bundle P and the separation claw 16 is smaller than the angle θ1 in the full state.

  As described above in detail, the sheet conveyance path 20 is disposed in the upper part of the sheet cassette 10 in the width direction. Accordingly, the overall width of the image forming apparatus 100 according to the present embodiment is not so different from the width of the paper feed cassette 10. That is, the size of the image forming apparatus 100 of this embodiment is smaller than that of the conventional image forming apparatus.

5. Modified example 5-1. Here, a modified example of this embodiment will be described. In this embodiment, the sheet feeding cassette body 11 is provided with the inclined surface 11b. However, it is not always necessary to provide the inclined surface 11b. As shown in FIG. 10, a paper feed cassette 210 without the inclined surface 11b may be used. The sheet cassette main body 211 of the sheet cassette 210 has a rear end portion 211E that is not inclined toward the rear end side of the sheet bundle P.

  As shown in FIG. 10, when the paper feed roller 14 is rotated in the reverse direction (rotated in the direction of the arrow DR in FIG. 10), the uppermost sheet P <b> 1 is sent out to the opposite side of the sheet conveyance path 20. At that time, the trailing edge PE of the sheet P1 is curved while being in contact with the trailing edge 211E of the sheet feeding cassette body 211. The sheet P1 is separated from the sheet bundle P by this curvature. Since some static electricity of the sheet P1 escapes to the atmosphere, the sheet P1 is difficult to stick to the sheet bundle P again. Further, the image forming apparatus provided with the paper feed cassette 210 has a smaller overall width than the image forming apparatus 100 of this embodiment. This is because the width for providing the inclined surface 11b is not necessary.

5-2. As shown in FIG. 11, the shape of the push-up plate 313 on which the sheet bundle P is placed may be a bent shape that is more bent than the push-up plate 13 in the form of FIG. In the sheet feeding cassette 310, the sheet bundle P is also placed on the push-up plate 313 while being curved so as to be convex upward. Therefore, even when the uppermost sheet P1 is sent out, it is easy to separate and feed out the uppermost sheet P1 from the sheet bundle P. In addition, the sound during paper separation is quieter. Of course, the shape of the push-up plate may be a curved shape that is convex upward.

5-3. High Friction Member As shown in FIG. 12, a paper feed cassette 410 having a high friction member 412 may be used. The inclined surface 11b (see FIG. 3 etc.) of the paper feed cassette body 11 is a high friction member. Therefore, the position where the high friction member 412 is disposed is the position on the sheet rear end side in the sheet feeding cassette body 411. Here, the high friction member 412 has a coefficient of friction larger than the material of the portion other than the inclined surface 11b in the paper feed cassette 410, and the material is cork, rubber, or the like. For this reason, the uppermost sheet P1 can be easily separated from the sheet bundle P by the separation claw 16.

6). Summary As described above in detail, the image forming apparatus 100 according to the present embodiment supplies the sheet feeding roller 14 and the separation claw 16 for conveying the sheet P1 toward the upper side of the sheet feeding cassette body 11. The paper cassette 10 has a width W1. Therefore, the image forming apparatus 100 is realized that can sequentially feed the sheets P1 from the sheet bundle P one by one and transport the sheets P1 to the sheet transport path 20 located above the sheet feeding cassette 10.

  Further, in the image forming apparatus 100 of the present embodiment, the sheet conveyance path 20 is also disposed at the upper portion within the range of the width W1 of the paper feed cassette 10. Accordingly, the overall width W of the image forming apparatus 100 of the present embodiment is not so different from the width W1 of the paper feed cassette 10. That is, the size of the image forming apparatus 100 of this embodiment is smaller than that of the conventional image forming apparatus. Thus, a downsized image forming apparatus is realized.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, it is not limited to a monochrome printer. That is, it is not limited to monochrome. It is not limited to printers. A copier may be used. Further, the present invention can be applied to an image reading apparatus and an image forming apparatus that transmit / receive a print job through a public line. Of course, it may be a multifunction machine. Also, it can be applied regardless of the type of toner.

10, 210, 310, 410 ... paper feed cassettes 11, 211, 411 ... paper feed cassette bodies 11a, 211a, 411a ... bottom plate 11b ... inclined surfaces 11T, 211T, 411T ... front end portions 11E, 211E, 411E ... rear end portions 12 ... Push-up springs 13, 313 ... Push-up plate 14 ... Feeding roller 15 ... Guide member 16 ... Separating claw 17 ... Conveying roller 18 ... Pressing spring 20 ... Sheet conveying path 30 ... Image forming unit 40 ... Transfer roller 50 ... Fixing device 61 ... Paper discharge roller pair 62 ... Paper discharge tray 90 ... Control unit 100 ... Image forming apparatus 412 ... High friction member P ... Sheet bundle P1 ... Sheet PT ... Front end PE ... Rear end

Claims (6)

A sheet feeding cassette for storing the sheet bundle, a separating member for separating the sheet from the sheet bundle accommodated in the sheet feeding cassette, and a feeding unit for feeding the uppermost sheet from the sheet bundle accommodated in the sheet feeding cassette. In an image forming apparatus having a paper roller, an image forming unit that forms an image on a sheet fed from the paper feed cassette, and a sheet conveyance path positioned between the paper feed cassette and the image forming unit,
The image forming unit and the sheet conveyance path are:
The sheet feeding cassette is disposed within a range from the front end to the rear end in the sheet feeding direction and above the sheet feeding cassette;
The tip of the separating member is
Arranged at a position between the front end and the rear end of the paper feed cassette;
The paper feed roller is
An image forming apparatus, wherein the image forming apparatus is disposed between a front end and a rear end of the paper feed cassette and at a position close to a rear end side of the paper feed cassette from a front end position of the separation member. . The image forming apparatus according to claim 1,
The paper feeding roller has a control unit that reversely rotates the uppermost sheet of the sheet bundle in the reverse direction of the sheet conveying path and then forwardly rotates the sheet in the direction of the sheet conveying path. Image forming apparatus. The image forming apparatus according to claim 2,
The amount of reverse rotation of the paper feed roller by the control unit is
An image forming apparatus having a rotation amount for moving the leading end of a sheet to a position between the leading end of the separation member and the sheet feeding roller. An image forming apparatus according to any one of claims 1 to 3, wherein
The paper cassette is
An image forming apparatus having a bent or curved push-up plate for placing a sheet bundle in a state of being curved upwardly in a convex shape. An image forming apparatus according to any one of claims 1 to 3, wherein
In the paper cassette,
2. An image forming apparatus according to claim 1, wherein an inclined surface is provided at a rear end portion of the paper feed cassette so as to extend away from the bottom plate of the paper feed cassette. The image forming apparatus according to claim 5, wherein
The inclined surface is
An image forming apparatus comprising a high friction member.

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