JP4333520B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copier, or a facsimile that forms an image on paper (plain paper, cardboard, postcard, envelope, OHP sheet, or other recording material). In particular, the present invention relates to a paper feed tray that feeds sheets stacked on the paper feed tray to an image forming unit.

2. Description of the Related Art Conventionally, an image forming apparatus in which a paper feed tray is provided so as to be openable and closable with respect to a side surface is known (see, for example, Patent Document 1).
There is also known a paper feeding device that separates the uppermost paper and the next paper with a retard roller that contacts the paper feeding roller (see, for example, Patent Document 2).
JP-A-4-49149 JP 2004-123359 A

In a paper feed device with a retard roller, when the paper feed tray is configured to be openable and closable with respect to the side surface of the image forming apparatus (a surface parallel to the axis of the paper feed roller), in the process of closing the paper feed tray, The tip of the lift plate may come into contact with the retard roller.
For this reason, there is a problem that the paper feed tray cannot be properly closed or the lift plate or the like may be damaged.
An object of the present invention is to provide an image forming apparatus capable of solving the above-described problems and appropriately closing a paper feed tray without causing damage to a lift plate or the like.

In order to achieve the above object, an image forming apparatus according to the present invention includes a paper feed roller that abuts on the topmost paper among the stacked paper and feeds the topmost paper;
A retard roller that contacts the paper feed roller to separate the uppermost paper and the next paper;
A feeding plate that supports a sheet to be fed by the sheet feeding roller and presses a front portion of the sheet against the sheet feeding roller, and a support body that rotatably supports the lifting plate. A paper tray,
An image forming apparatus in which the paper feed tray is configured to be openable and closable with respect to a side surface of the image forming apparatus,
The rotation center axis of the lift plate is supported by a slot provided in the support body of the paper feed tray, and the rotation plate is between the support body and the rotation center axis of the lift plate. An urging member that urges a central axis toward an end portion of the elongated hole on the sheet feeding roller side is provided.
According to such a configuration, when the paper feed tray is closed with respect to the side surface of the image forming apparatus, even if the front end of the lift plate comes into contact with the retard roller in the process, the rotation center axis of the lift plate is The lift plate moves backward by moving along the elongated hole of the support body against the urging force of the urging member.
Therefore, the paper feed tray can be properly closed without causing damage to the lift plate or the like.
On the other hand, when the paper feed tray is opened, the pivoting central axis of the lift plate is urged toward the end of the elongated hole on the side of the paper feed roller by the urging force of the urging member. Is positioned.
Therefore, an appropriate paper feeding operation is ensured.
When a side cover that can be opened and closed with respect to the image forming apparatus main body is provided on the side surface of the image forming apparatus, the paper feed tray is provided so as to be openable and closable with respect to the side cover.
As a result, the image forming apparatus can be reduced in size.
In this case, preferably, the side surface of the side cover in the closed state and the side surface of the paper feed tray in the closed state form substantially the same surface.
As a result, the image forming apparatus can be miniaturized and at the same time the appearance can be made clear.
Further, in such a case, if the paper feed roller and the retard roller are provided close to the closed side cover, when the paper feed tray is closed, the leading end of the lift plate is retarded. Although it is easy to come into contact with the roller, according to the present invention, as described above, it is possible to properly close the paper feed tray without causing damage to the lift plate or the like.
In other words, even when the paper feed roller and the retard roller are provided close to the closed side cover, the paper feed tray can be provided to be openable and closable with respect to the side cover. In addition, it is possible to form substantially the same surface by the side surface of the side cover in the closed state and the side surface of the paper feed tray in the closed state.
Desirably, a duplex unit for enabling image formation on both sides of the sheet is detachably attached to the upper portion of the side cover.
As a result, it is possible to reduce the size of the image forming apparatus when the duplex unit is attached.
In this case, the paper feed tray is provided at the lower part of the side cover so that it can be opened and closed.
As a result, the image forming apparatus can be downsized.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic front view showing the structure of an embodiment of an image forming apparatus according to the present invention.
This image forming apparatus is a color image forming apparatus capable of longitudinally feeding A4 size paper (including letter size) to form a full color image on both sides thereof. The image forming apparatus is accommodated in a case 10 and the case 10. , An image carrier unit 20, an exposure unit 30 as an exposure unit, a developing unit (developing device) 40 as a developing unit, an intermediate transfer unit 50, and a fixing unit (fixing unit) 60 as a fixing unit. I have.
The case 10 is provided with a frame (not shown) of the apparatus main body, and each unit is attached to the frame.

  The image carrier unit 20 includes a photoconductor 21 having a photosensitive layer on the outer peripheral surface, and a corona charger (scorotron charger) 22 as a charging unit that uniformly charges the outer peripheral surface of the photoconductor 21. The outer peripheral surface of the photoconductor 21 uniformly charged by the corona charger 22 is selectively exposed with the laser light L from the exposure unit 30 to form an electrostatic latent image. The developer 40 is applied with a toner as a developer to form a visible image (toner image). This toner image is primarily transferred to the intermediate transfer belt 51 of the intermediate transfer body unit 50 by the primary transfer portion T1, and further to the second image. The secondary transfer unit T2 performs secondary transfer onto a sheet to be transferred.

In the case 10, a conveyance path 16 that conveys a sheet on which an image is formed on one side by the secondary transfer portion T <b> 2 toward a sheet discharge portion (discharge tray portion) 15 on the top surface of the case 10, and the conveyance path 16 A return path 17 is provided for switching back the sheet conveyed toward the sheet discharge unit 15 and returning it to the secondary transfer unit T2 so as to form an image on the other side.
Reference numeral 70 denotes a double-sided unit configured to be attachable to and detachable from a side cover 10c provided so as to be openable and closable with respect to the image forming apparatus by a shaft 10d. It is formed.
The lower portion of the case 10 is provided with two stages of paper feed cassettes 18 for laminating and holding a plurality of paper sheets, and a paper feed roller 19 for feeding the paper sheets one by one toward the secondary transfer portion T2. Each is provided.

Below the duplex unit 70, there is provided a multi-purpose tray 100 which forms a paper feeding device 80, which is a main part of the present invention, and the paper set on the multi-purpose tray 100 is fed one by one. A paper roller 90 is provided in the apparatus main body.
The sheet feeder 80 and the like will be described in detail later.

  The developing device 40 is a rotary developing device (rotary developing device), and a plurality of developing device cartridges (not shown) each containing toner are detachably attached to the rotating body main body 41. As the rotating body 41 rotates at 90 ° pitch in the direction of arrow R, the developing roller (not shown) provided in each developing device cartridge is selectively brought into contact with the photosensitive member 21, and the surface of the photosensitive member 21. Can be selectively developed.

The exposure unit 30 irradiates the laser 21 with the laser light L.
The intermediate transfer unit 50 includes a unit frame (not shown), a drive roller 54 rotatably supported by the frame, and the intermediate transfer belt 51 stretched around a plurality of driven rollers. The intermediate transfer belt 51 is circulated and driven in the direction of the arrow shown in the figure. The primary transfer portion T1 is formed at the contact portion between the photosensitive member 21 and the intermediate transfer belt 51, and the secondary transfer portion T2 at the pressure contact portion between the driving roller and the secondary transfer roller 10b provided on the main body side. Is formed.
The secondary transfer roller 10b can be brought into contact with and separated from the drive roller 54 (and therefore with respect to the intermediate transfer belt 51), and when it comes into contact, a secondary transfer portion T2 is formed.
Accordingly, when forming a color image, a plurality of color toner images are superimposed on the intermediate transfer belt 51 while the secondary transfer roller 10b is separated from the intermediate transfer belt 51, and then a color image is formed. The secondary transfer roller 10b contacts the intermediate transfer belt 51, and the sheet is supplied to the contact portion (secondary transfer portion T2), whereby a color image (toner image) is formed on the sheet from the intermediate transfer belt 51. Transfer (secondary transfer) is performed.
The sheet on which the toner image has been transferred passes through the fixing unit 60 to melt and fix the toner image, and is discharged toward the paper discharge tray unit 15.

Sheet feeding to the image forming unit is selectively performed from one of the two-stage sheet feeding cassette 18 and the multi-purpose tray 100 described above.
Normally, plain paper or the like is normally set in the paper feed cassette 18, but various papers are set in the multi-purpose tray 100 as necessary. In other words, plain paper, cardboard, postcards, envelopes, OHP sheets, and other recording materials are appropriately set in the multi-purpose tray 100 as required by the user.

FIG. 2 is a partially enlarged view of FIG. 3 is a plan view of the main part, and FIG. 4 is a partially enlarged view (partial perspective view) of FIG.
As shown in these drawings (mainly FIG. 2), the paper feeding device 80 is in contact with the uppermost paper among the stacked paper S, and feeds the uppermost paper. A retard roller 130 that comes into contact with the paper feed roller 90 to separate the uppermost paper and the next paper, and supports the paper S to be fed by the paper feed roller 90, and the front part S1 of the paper S. A sheet feeding tray (multi-purpose tray) 100 having a lift plate 111 that presses the sheet feeding roller 90 and a tray main body 112 as a support that rotatably supports the lift plate 111. .
The multi-purpose tray 100 includes a first tray 110 and a second tray 120, and is configured to be openable and closable with respect to the side surface of the image forming apparatus as will be described later.

Reference numeral 130 denotes a retard roller with a torque limiter that comes into contact with the paper feed roller 90, and the retard roller 130 separates the uppermost sheet and the next sheet.
The retard roller 130 is rotatably attached to the fixed shaft 131 via a torque limiter 132 (see FIG. 3), and is always in the direction of the arrow (in the same direction as the paper feed roller 90) by a spring built in the torque limiter 132. Yes, clockwise in FIG.
Therefore, when the uppermost sheet is to be fed by the sheet feeding roller 90 and the next or lower sheet is to be fed along with this, rotation of the retard roller 130 is hindered by the load torque by the torque limiter 132. When the feeding of the next sheet is obstructed and only the uppermost sheet is nipped between the sheet feeding roller 90 and the retard roller 130 and exceeds the upper limit torque of the torque limiter 132, the retard roller 130 is moved to the sheet feeding roller. 90 is driven via the uppermost sheet, so that only the uppermost sheet is fed.

  As shown in FIG. 1, the multi-purpose tray 100 is attached to a side cover 10c of the main body case 10 of the image forming apparatus by a shaft 101 so as to be opened and closed. The side cover 10c is configured to be openable and closable with respect to the image forming apparatus main body by a shaft 10d. FIG. 1 shows a state in which the side cover 10c is closed and the multi-purpose tray 100 is opened and usable.

As shown in FIGS. 2 and 3, the first tray 110 is attached to a substantially box-shaped tray body (support) 112 and both side plates 113 of the tray body 112 so as to be rotatable about a rotation center shaft 114. The lift plate 111 is also provided.
The rotation center shaft 114 of the lift plate 111 is rotatably supported by elongated holes 113a (see FIG. 4) provided in both side plates 113 of the tray body 112, and the rotation of the tray body 112 and the lift plate 111 is rotated. Between the moving center shaft 114, a torsion spring 102 as a biasing member that biases the rotation center shaft 114 toward the end portion 113a1 (see FIG. 4) of the elongated hole 113a on the sheet feeding roller 90 side. Is provided.
As shown in FIG. 4, the torsion spring 102 is attached to a pin 113 b provided on the inner surface of the side plate 113, one end 102 a is hooked on the tray body 112, and the other end 102 b is the rotation center shaft 114. By being in contact with the boss portion 114a, the rotation center shaft 114 is urged toward the paper feed roller 90 side.
The direction of the long hole 113a is arbitrary as long as its long axis is not perpendicular to the line connecting the center of the rotation center shaft 114 and the center of the retard roller 130.

As shown in FIG. 1, the image forming apparatus main body is provided with a push-up plate 91 that pushes up the lift plate 111. The base of the push-up plate 91 is attached to the image forming apparatus main body, and the tip of the push-up plate 91 enters below the lift plate 111.
The push-up plate 91 is provided with a biasing member (not shown) (not shown) that constantly biases the push-up plate 91 in the push-up direction, and the multi-purpose tray 100 (and hence the first tray 110) is opened as shown in FIG. When pushed, the tip of the push-up plate 91 always urges the lift plate 111 upward, and the tip of the paper is pressed toward the paper feed roller 90, but the image forming apparatus main body has a cam (not shown). (A cam that operates in conjunction with the paper feeding operation) is provided, and when the push-up plate 91 is pushed down by this cam, the press of the paper to the paper feed roller 90 by the lift plate 111 is released. .

  As shown in FIG. 3, side guides 115 and 116 that are slidable in the width direction (vertical direction in FIG. 3) are attached to the lift plate 111. The side guide is for guiding the side edge of the fed paper. A rack 117 is integrally provided at the bottom of each of the side guides 115 and 116, and these racks 117 mesh with a gear 118 provided on the lift plate 111. Therefore, when one side guide 115 or 116 is slid, the other side guide is also slid, so that the center of the sheet coincides with the position of the sheet feeding roller 90.

The second tray 120 can be stored in the first tray 110 (below the lift plate 111) and can be pulled out.
As shown in FIG. 2, when the second tray 120 is pulled out from the first tray 110, protrusions 122 provided at both ends of the lower end of the second tray 120 are provided on the inner surface of the side plate 113 of the first tray 110. As shown in FIG. 3, ribs 123 provided on both sides of the second tray 120 are provided on the first tray 110. By contacting the rib 119, the inclination angle is defined.

  As shown in FIGS. 2 and 3, an auxiliary tray 124 is rotatably connected to the rear portion of the second tray 120 by a shaft 125. The auxiliary tray 124 can be rotated 180 degrees around the axis 125. 2 and 3 show a state in which the auxiliary tray 124 is opened, the auxiliary tray 124 can be stored in the upper surface recess 126 (see FIG. 3) of the second tray 120 by rotating it 180 degrees. It is. The auxiliary tray 124 is opened and used when supporting legal size paper.

As shown in FIG. 1, a pair of left and right links 104 (see FIG. 3) are provided between the first tray 110 of the multi-purpose tray 100 and the side cover 10c.
As shown in FIG. 2, a long hole 105 is provided in the link 104, and its upper end is rotatable and slidable with respect to a pin 10e (see FIG. 1) provided on the inner surface of the side cover 10c. Is engaged.
On the other hand, a shaft 106 is provided at the lower end of the link 104, and this shaft 106 is rotatably engaged with a hole 113c provided in the side plate 113 of the tray body 112 as shown in FIG. .
Therefore, when the multi-purpose tray 100 is opened as shown by a solid line in FIG. 1, the link 104 supports the multi-purpose tray 100 and positions the multi-purpose tray 100 with respect to the side cover 10c.
Further, the multi-purpose tray 100 has the side cover 10c as shown in phantom lines in FIG. 1 in a state where the auxiliary tray 124 is folded on the second tray 120 and the second tray 120 is stored in the first tray 110. When the multi-purpose tray 100 is closed, the link 104 is accommodated in the side cover 10c as indicated by a virtual line.

As shown in phantom lines in FIG. 1, when the multi-purpose tray (paper feed tray) 100 is closed, the side surface (surface parallel to the axis of the paper feed roller 90) of the closed side cover 10c is closed. The side surface of the sheet feeding tray 100 in the state is substantially the same surface.
In addition, the duplex unit 70 is detachably attached to the upper part of the side cover 10c, and the paper feed tray 100 is detachably provided at the lower part of the side cover 10c.
As shown in FIG. 1, the paper feed roller 90 and the retard roller 130 are provided close to the closed side cover 10c.

According to the image forming apparatus as described above, the following effects can be obtained.
The image forming apparatus includes a paper feed roller 90 that abuts on the topmost paper among the stacked paper S and feeds the topmost paper, and a paper feed roller 90 that abuts on the paper feed roller 90 and the topmost paper. A retard roller 130 that separates the paper from the next paper, a lift plate 111 that supports the paper S to be fed by the paper feed roller 90 and presses the front S1 of the paper against the paper feed roller 90, and A sheet feeding tray 100 having a support 112 that rotatably supports a lift plate 111. The sheet feeding tray 100 is configured to be openable and closable with respect to the side surface of the image forming apparatus. A rotation center axis 114 of the plate 111 is supported by a long hole 113 a provided in the support body 112 of the paper feed tray 100, and between the support body 112 and the rotation center axis 114 of the lift plate 111, Center of rotation Since the biasing member 102 is provided to bias 114 toward the end 113a1 on the paper feed roller 90 side in the long hole 113a, when the paper feed tray 100 is closed with respect to the side surface of the image forming apparatus, In the process, even if the tip of the lift plate 111 abuts against the retard roller 130, the rotation center shaft 114 of the lift plate 111 resists the biasing force of the biasing member 102 and follows the elongated hole 113 a of the support 112. The lift plate 111 moves backward.

In the case of this embodiment, the lift plate 111 is lifted up for some reason (for example, the user turns off the apparatus power when the lift plate 111 is in the lift-up position (see reference numeral 111b in FIG. 2)). When the sheet feeding tray 100 is closed while being in the position, the tip of the lift plate 111 comes into contact with the retard roller 130 in the process, and at this time, the rotation center shaft 114 of the lift plate 111 is moved. The lift plate 111 moves backward by moving in the direction away from the retard roller 130 (to the right in FIGS. 2 and 4) along the elongated hole 113 a of the support 112 against the urging force of the urging member 102.
Therefore, it is possible to properly close the paper feed tray 100 without causing damage to the lift plate 111 and the like.

On the other hand, when the paper feed tray 100 is opened, the rotation center shaft 114 of the lift plate 111 is moved by the biasing force of the biasing member 102, as shown in FIGS. By being biased toward 113a1, positioning with respect to the support 112 (and hence the paper feed roller 90) is performed.
Therefore, an appropriate paper feeding operation is ensured.
Note that the urging force by the urging member 102 causes the lift plate 111 to retract when the lift plate 111 contacts the retard roller 130, and when the paper feed tray 100 is opened, the pivot center shaft 114 of the lift plate 111. Is pressed against the end 113a1 on the paper feed roller side in the long hole 113a so that the urging force can be positioned.

In this image forming apparatus, the side cover 10c that can be opened and closed with respect to the image forming apparatus main body is provided on the side surface, and the paper feed tray 100 is provided so as to be openable and closable with respect to the side cover 10c. The forming apparatus can be downsized.
Moreover, as indicated by the phantom line in FIG. 1, the side surface of the side cover 10c in the closed state and the side surface of the paper feed tray 100 in the closed state form substantially the same surface. Can be reduced in size, and at the same time, the appearance can be made clearer.
Furthermore, when the paper feed roller 90 and the retard roller 130 are provided close to the closed side cover 10c as in this image forming apparatus, the lift plate is used when the paper feed tray 100 is closed. Although the leading end of 111 is likely to come into contact with the retard roller 130, according to this embodiment, it is possible to properly close the paper feed tray 100 without causing damage to the lift plate 111 or the like as described above. .
In other words, according to this embodiment, the sheet feed tray 100 is mounted on the side cover even though the sheet feed roller 90 and the retard roller 130 are provided close to the closed side cover 10c. The side surface of the side cover 10c in the closed state and the side surface of the paper feed tray 100 in the closed state can form substantially the same surface. It will be possible.

  Further, according to this embodiment, the paper feed tray 100 is closed in the side cover 10c in a compact state as described above, and the link 104 that supports the paper feed tray 100 when the paper feed tray 100 is opened is The pin 10e provided on the inner surface of the side cover 10c is connected to an intermediate portion (a hole 113c in this embodiment) between the rotation shaft 101 and the rotation center shaft 114 of the lift plate 111 in the tray body 112. With this configuration, the link 104 is configured to be short, and the link 104 is accommodated in the side cover 10c, whereby the duplex unit 70 is detachably attached to the upper portion of the side cover 10c and the side cover 10c. Since the paper feed tray 100 is openable and closable at the bottom of the image forming apparatus, the image forming apparatus when the duplex unit is attached is provided. It is possible to achieve the type of.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the gist of the present invention.

1 is a schematic front view showing an internal structure of an example of a color image forming apparatus using an embodiment of a paper feeding device according to the present invention. The elements on larger scale of FIG. The top view of the principal part of FIG. FIG. 3 is a partially transparent enlarged view of a part omitted in FIG. 2.

Explanation of symbols

  S: paper, S1: front, 10c: side cover, 70: duplex unit, 90: paper feed roller, 100: paper feed tray, 102: torsion spring (biasing member), 110: first tray, 111: lift Plate, 112: tray body (support), 113a oblong hole, 113a1: end on the sheet feeding roller side, 114: rotation center axis, 120: second tray, 130: retard roller, 132: torque limiter.

Claims (4)

A paper feed roller that abuts on the topmost paper among the stacked paper and feeds the topmost paper;
A retard roller that contacts the paper feed roller to separate the uppermost paper and the next paper;
A feeding plate that supports a sheet to be fed by the sheet feeding roller and presses a front portion of the sheet against the sheet feeding roller, and a support body that rotatably supports the lifting plate. A paper tray,
An image forming apparatus in which the paper feed tray is configured to be openable and closable with respect to a side surface of the image forming apparatus,
The rotation center axis of the lift plate is supported by a slot provided in the support body of the paper feed tray, and the rotation plate is between the support body and the rotation center axis of the lift plate. An image forming apparatus, comprising: a biasing member that biases a central axis toward an end of the elongated hole on the paper feed roller side.   A side cover is provided on the side surface so as to be openable and closable with respect to the image forming apparatus main body. The paper feed tray is openable and closable with respect to the side cover, and the paper feed roller and retard 2. The image forming apparatus according to claim 1, wherein a roller is provided in the vicinity of the side cover in a closed state.   The image forming apparatus according to claim 2, wherein a side surface of the side cover in the closed state and a side surface of the paper feed tray in the closed state form substantially the same surface.   A duplex unit for enabling image formation on both sides of the sheet is detachably attached to the upper part of the side cover, and the paper feed tray is detachably provided at the lower part of the side cover. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.

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