JPH07215511A - Sheet loading device, sheet feeding device, and image forming device - Google Patents

Abstract

PURPOSE:To prevent a defective sheet feed or a defective image caused by friction electrified charges when sheets are fed by providing a sheet storage means and a sheet holding means, and guiding the charges from the sheet holding means to the outside of the sheet storage means with a conducting means. CONSTITUTION:The second conducting member 21b is a conducting compression coil spring, and it is elastically deformed when a cassette 9 is fitted to a image forming device main body 20. One end of the second conducting member 21b is fixed to the image forming device main body 20, the other end is a free end and is kept in contact with the shaft of the first conducting member 21a on the cassette 9 side when the cassette 9 is inserted into the device main body 20. A conducting member 21 causes no defective contact even if the cassette 9 is moved in the device. When electrification occurs due to friction while sheets are fed, electrified charges can be released from sheets to the outside of the device main body 20 through the intermediate plate 10 of the cassette 9, the first conducting member 21a, and the second conducting member 21b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet stacking apparatus for stacking and storing sheets, and more particularly to a sheet stacking apparatus which can be attached to and detached from an image forming apparatus such as a copying machine, a facsimile, a printer or the like.

[0002]

2. Description of the Related Art In recent years, as shown in FIG. 4, in a sheet feeding section of an image forming apparatus such as a copying machine, a sheet S in a sheet feeding cassette 51 is lifted up by an intermediate plate 52 and picked up by a pickup roller 53. In most cases, the sheet is fed by pressing and rotating the roller 53.

The paper feed cassette 51 is detachably attached to the image forming apparatus main body 55 as shown in FIG.

[0004]

However, in the sheet feeding system using the pickup roller 53, the sheet S and the intermediate plate 52 are charged due to the friction during the sheet feeding, and the electrification charge causes the sheet feeding failure and the image. There is a problem that defects and the like occur. That is, at the time of sheet feeding as shown in FIG. 4A, the sheet S is rubbed by the friction between the pickup roller 53 and the uppermost sheet S ₁ and the friction between the uppermost sheet S ₁ and the sheet S ₂ below it. Get charged. When the sheet is fed as shown in FIG. 4B, the middle plate 52 is charged by the friction between the pickup roller 53 and the sheet S and the friction between the sheet S and the middle plate 52.

In order to solve the above problem, it is conceivable to ground the image forming apparatus main body from the middle plate in the paper feed cassette by using a lead wire or a rigid body, but the middle plate rotates with the lead wire. In the rigid body, when the position adjustment for matching the original image and the image recorded on the sheet is performed, the cassette moves in the main body of the image forming apparatus, so that the contact failure occurs in the rigid body. As a result, there is a problem in that the electric charges charged on the sheet and the intermediate plate cannot escape, and as described above, the sheet conveyance failure or the image failure due to the frictional electrification occurs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent sheet feeding failure and image failure due to triboelectric charge during sheet feeding.

[0007]

A typical sheet stacking device of the present invention that achieves the above object has a sheet storing means for storing sheets, and a sheet rotatably supported by the sheet storing means. It is characterized by having a sheet holding means for holding and a conductive means for guiding electric charges from the sheet holding means to the outside of the sheet storing means.

A typical image forming apparatus according to the present invention which achieves the above-mentioned object has a sheet stacking means which is detachable from the apparatus body and stacks and stores sheets, and conveys the sheets from feeding to discharging. Sheet conveying means, an image forming means for forming an image on the sheet, and a conductive means interposed between the sheet stacking means and the apparatus main body, wherein the conductive means is a first stacker on the sheet stacking means side. It is characterized by comprising one conductive means and a second conductive means on the apparatus body side.

A typical sheet feeding device according to the present invention which achieves the above-mentioned object is detachably provided in the main body of the device.
A sheet storage means for storing a sheet, a sheet holding means for holding the sheet rotatably supported by the sheet storage means by a rotation shaft parallel to a mounting direction of the sheet storage means, and the sheet storage means. A sheet feeding means for feeding the accommodated sheets in a direction orthogonal to the mounting direction of the sheet accommodating means, and a space between the rotating shaft and the apparatus body for guiding electric charges from the sheet holding means to the apparatus body. And a conductive means disposed at.

The conductive means is a conductive elastic member interposed between the sheet storage means and the apparatus main body, and is elastically deformed when the sheet storage means is attached to the apparatus main body to store the sheet. It is characterized in that the means is biased in the pull-out direction.

Further, the apparatus main body has lock means for locking the sheet storage means at a mounting position, and the lock means is a reference for urging and positioning the sheet storage means by the elastic member. It is characterized by having a face.

[0012]

According to the above construction, even if electrification occurs due to friction during sheet feeding, the electrified electric charge can be released from the sheet to the outside of the apparatus through the sheet holding means and the conductive means, or from the sheet. The sheet can be released to the outside of the device through the sheet holding means, the first conductive means, and the second conductive means.

Further, even if there is a risk that the sheet storage means and the apparatus main body collide when the sheet storage means is suddenly pushed in, the elastic member as the conductive means buffers the shock and deforms the sheet storage means and the apparatus main body. It will not be damaged. That is, the elastic member serves as both the conductive member and the cushioning member.

Further, since the sheet storing means is biased in the pull-out direction by the elastic member which is the conductive means, the force for pulling out is small and the operability is improved.

Further, by providing the reference surface of the lock means and pressing the sheet storage means against the reference surface by the conductive means which is an elastic member, the sheet storage means can be accurately positioned with respect to the main body of the apparatus, and sheet feeding accuracy is improved. Can be increased. That is, the elastic member serves as both the conductive member and the positioning member.

[0016]

【Example】

[First Embodiment] Next, a sheet stacking apparatus according to an embodiment of the present invention to which the above means is applied will be described with reference to the drawings. In this embodiment, a sheet stacking device equipped in an electrophotographic copying machine as an image forming apparatus will be described. Figure 1
FIG. 2 is a cross-sectional view showing a state in which the paper feed cassette is inserted in the electrophotographic copying machine, FIG. 2 is a side view showing a state in which the paper feeding cassette is attached to and detached from the copying machine main body, and FIG. 3 is a schematic configuration diagram of the electrophotographic copying machine.

First, the schematic construction of the electrophotographic copying machine will be described with reference to FIG. In FIG. 3, reference numeral 1 denotes a document table glass for stacking documents, on which a document to be copied is placed. Reference numeral 2 denotes an exposure device, which moves in the direction of arrow a and scans the entire surface of the original while irradiating the original placed on the original table glass 1 with light.

The reflected light obtained by illuminating the original with the exposure device 2 is imaged on the photosensitive drum 5 via the first mirror group 3a, the zoom lens 4 and the second mirror group 3b. An electrostatic latent image is formed.

Around the photosensitive drum 5, a charging means 6, a developing means 7, a cleaning means 8 and the like are provided as process means contributing to image formation. The electrostatic latent image formed on the photosensitive drum 5 is developed and visualized by the developing means 7.

Reference numeral 9 denotes a paper feed cassette for stacking and storing the sheets S, which is installed at the bottom of the apparatus main body so as to be drawn out.
As will be described later, the paper feed cassette 9 has a structure in which a conductive member is interposed between the paper feed cassette 9 and the main body of the device, and the charged electric charge can be released. The sheet S stored in the paper feed cassette 9 is lifted up by the intermediate plate 10 and is pressed against the feeding roller 11. A separation pad 12 is pressed against the feeding roller 11.

When the feeding roller 11 rotates, it is fed from the uppermost sheet S, and when passing between the feeding roller 11 and the separation pad 12, the sheets are separated and fed one by one. Then, the separated and fed sheet S is guided through the conveyance guide 13 to the pair of registration rollers 14 which is temporarily stopped. The registration roller pair 14 synchronizes with the developed image formed on the photosensitive drum 5 and conveys the sheet S to the transfer portion.

A transfer roller 15 is in pressure contact with the photosensitive drum 5. The developed image is transferred to the sheet S conveyed by the pair of registration rollers 13 when passing between the photosensitive drum 5 and the transfer roller 15. The sheet S after the image transfer is conveyed by the conveying device 16, and when passing through the fixing unit 17, heat and pressure are applied to fix the transferred image. Then, the sheet P after the image fixing is conveyed and discharged to the discharge tray 19 by the discharge roller pair 18.

Next, the construction of the paper feed cassette 9 will be described with reference to FIGS. The paper feed cassette 9 that can be pulled out to the image forming apparatus main body 20 is, as shown in FIG.
Conductive member 21 for releasing charged electric charge generated by friction
have. The conductive member 21 includes a first conductive member 21a that guides electric charges from the intermediate plate 10 to the outside of the cassette 9, and a second conductive member 21b that connects the apparatus body 20 and the first conductive member 21a.

The first conductive member 21a is a shaft which is a fulcrum of rotation of the intermediate plate 10 and penetrates the inside and outside of the cassette 9. As a result, the first conductive member 21a and the intermediate plate 10 are always in contact with each other. Further, since the first conductive member 21a is the fulcrum of rotation of the intermediate plate 10, the load on the rotation of the intermediate plate 10 is minimized.

The second conductive member 21b is a conductive elastic member and is elastically deformed when the cassette 9 is mounted on the apparatus main body 20. In this embodiment, a compression coil spring is used as the elastic member. The compression coil spring 21b, which is the second conductive member, has one end at the image forming apparatus main body 20.
The other end is a free end and comes into contact with the shaft 21a which is the first conductive member on the cassette 9 side when the cassette 9 is inserted into the apparatus main body 20. By using the second conductive member 21b as an elastic member (compression coil spring in this embodiment), the conductive member 21 does not cause contact failure even when the cassette 9 moves in the apparatus.

With the above structure, even if charging occurs due to friction during sheet feeding, the charged charges of the apparatus main body 20 pass from the sheet S through the intermediate plate 9, the first conductive member 21a, and the second conductive member 21b. Can escape to the outside. Therefore, it is possible to prevent the sheet feeding failure, the image failure, and the like due to the frictional charge.

As shown in FIG. 2, the cassette 9 is provided with a rotatable handle 22, which is biased counterclockwise in the drawing by a spring (not shown) and is rotated by a stopper (not shown). It is stopped in the state shown in (a). A lock portion 22a is formed at an end portion of the handle 22 and can be engaged with an engagement hole 20a formed on the apparatus body 20 side.

As the cassette 9 is inserted, as shown in FIG.
As shown in (b), the handle 22 is rotated clockwise by the device body 20, and the lock portion 22a engages with the engagement hole 20a as shown in FIG. 2 (c). This state is the mounting completion state. Even when the cassette 9 is suddenly pushed in when the cassette 9 is attached, the coil spring 21
Since b is elastically deformed to absorb the shock, the cassette 9 and the apparatus main body 20 are not deformed and damaged. That is, the coil spring 21b which is the conductive member also serves as a buffer member.

Further, one end surface 20a1 of the engaging hole 20a serves as a reference surface for positioning the cassette 9 with respect to the apparatus body 20, and the cassette spring 9 is biased in the pull-out direction by a coil spring 21b which is a conductive member. As a result, the lock portion 22a comes into contact with the reference surface 20a1 and the cassette 9 is positioned. By positioning this cassette 9,
Positioning in the width direction is performed at the time of feeding the sheet, and the sheet can be supplied to the image forming unit with a high positional accuracy. That is, the coil spring 21b, which is the conductive member, also serves as a positioning member.

When the cassette 9 is pulled out, as shown in FIG. 2 (d), by grasping the handle 22 and turning it clockwise, the lock portion 22a comes out of the engaging hole 20a and the engaged state is maintained. After that, the cassette 9 can be pulled out. At this time, since the cassette 9 is biased in the pull-out direction by the coil spring 21b which is a conductive member, the cassette 9 can be pulled out with a light force, and the pull-out operation of the cassette 9 becomes easy.

[Other Embodiments] In the above-described embodiments, the compression coil spring is used as the elastic member which is the second conductive member 21b, but the present invention is not limited to this, and the original image is not limited thereto. When the position adjustment is performed in order to match the images recorded on the sheet and the sheet, an elastic member that can always maintain a contact state with the shaft of the intermediate plate 10 that is the first conductive member 21a may be used. For example, even if a leaf spring or the like is used as the elastic member, the same effect as that of the above-described embodiment can be obtained.

In the above-described embodiment, the first conductive member 21
Although the example in which the shaft of the intermediate plate 10 which is a and the intermediate plate 10 are configured by separate parts is shown, the present invention is not limited to this, and for example, the shaft and the intermediate plate as the first conductive member 21a. 10 and 10 may be integrated. With this configuration, the same effect as that of the above-described embodiment can be obtained.

Further, although the electrophotographic copying machine is exemplified as the image forming apparatus in the above-mentioned embodiment, the present invention is not limited to this, and other image forming apparatus such as a laser beam printer, a facsimile machine or a word processor can be used. It is also possible to use for.

Further, in the above-mentioned embodiment, the sheet stacking device which can be pulled out to the image forming apparatus main body is exemplified.
The present invention is not limited to this, and the present invention can be similarly applied to, for example, a sheet stacking device that can be attached to and detached from the image forming apparatus main body.

Further, in the above-described embodiment, the image forming apparatus in which the photosensitive drum and the process means acting on the photosensitive drum are directly arranged in the apparatus main body has been exemplified. For devices that mount cartridges to form images,
The present invention is similarly applicable.

[0036]

As described above, according to the present invention,
Even if electrification occurs due to friction during sheet feeding, the electrified charge can be guided from the sheet to the outside of the apparatus through the sheet holding means and the conducting means, or the electrified charge can be transferred from the sheet to the sheet holding means and the first conducting means. Since it can be guided to the outside of the apparatus through the second conductive means, it is possible to prevent sheet feeding failure, image failure and the like due to the charge.

Further, even when the sheet storage means is pushed in abruptly, the elastic member as the conductive means buffers the shock, so that the sheet storage means and the apparatus body are prevented from colliding and deforming and damaging. can do. Further, since the sheet storage means is biased in the pull-out direction by the elastic member that is the conductive means, the force for pulling out the sheet is small and the operability is improved. Moreover, since the sheet storage means is pressed against the reference surface of the lock means by the elastic member which is the conductive means, the sheet storage means can be accurately positioned with respect to the apparatus main body, and the sheet feeding accuracy can be improved. Further, since the elastic member serving as the conductive means also functions as the cushioning member and the positioning member as described above, the increase in the number of parts is prevented. As described above, according to the present invention, it is possible to provide a more excellent sheet stacking apparatus, sheet feeding apparatus, and image forming apparatus.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a state in which a paper feed cassette is inserted into a copying machine main body.

FIG. 2 is a side view showing a state in which a paper feed cassette is attached to and detached from a copying machine main body.

FIG. 3 is a schematic configuration diagram of an electrophotographic copying machine including a paper feeding cassette.

FIG. 4 is an explanatory diagram of a conventional technique.

FIG. 5 is an explanatory diagram of a conventional technique.

[Explanation of sign]

S ... Sheet, 1 ... Original platen glass, 2 ... Exposure device, 3a,
3b ... Mirror group, 4 ... Zoom lens, 5 ... Photosensitive drum, 6 ... Charging means, 7 ... Developing means, 8 ... Cleaning means, 9 ... Paper feeding cassette, 9a ... Sheet stacking surface, 10 ... Middle plate, 11 ... Feed roller, 12 ... Separation pad, 13 ... Conveying guide, 14 ... Registration roller pair, 15 ... Transfer roller, 16 ... Conveying device, 17 ... Fixing section, 18 ... Ejecting roller pair, 19 ... Ejecting tray, 20 ... Image forming Device main body, 20a ... Engagement hole, 20a1 ... End face (reference surface), 21 ... Conductive member, 21a ... First conductive member (shaft), 21b ... Second conductive member (compression coil spring), 22 ... Handle, 22a ... Lock part

Claims (10)

[Claims] 1. A sheet storage means for storing a sheet, a sheet holding means rotatably supported by the sheet storage means for holding the sheet, and an electric charge is guided from the sheet holding means to the outside of the sheet storage means. A sheet stacking device comprising: a conductive unit. 2. The sheet stacking apparatus according to claim 1, wherein the conductive means is a shaft that serves as a pivotal fulcrum of the sheet holding means. 3. The sheet stacking apparatus according to claim 1, wherein the conductive means and the sheet holding means are integrally provided. 4. A sheet stacking unit that is detachably mountable on the apparatus main body and stacks and stores sheets, a sheet transporting unit that transports the sheet from feeding to discharging, and an image forming unit that forms an image on the sheet. And a conductive means interposed between the sheet stacking means and the apparatus main body, wherein the conductive means is a first conductive means on the side of the sheet stacking means,
An image forming apparatus comprising a second conductive unit on the apparatus main body side. 5. In the conductive means, the first conductive means on the side of the sheet stacking means is a shaft that serves as a fulcrum of rotation of the sheet holding means, and the second conductive means on the side of the apparatus main body sets the sheet stacking means to the main body of the apparatus. The image forming apparatus according to claim 4, wherein the image forming apparatus is a fixed elastic member. 6. A sheet storage means detachably provided in the apparatus main body for storing a sheet, and rotatably supported by the sheet storage means by a rotation shaft parallel to a mounting direction of the sheet storage means, Sheet holding means for holding a sheet, sheet feeding means for feeding the sheet stored in the sheet storing means in a direction orthogonal to the mounting direction of the sheet storing means, and electric charge is introduced from the sheet holding means to the apparatus main body. Therefore, a sheet feeding device comprising: a conductive means disposed between the rotating shaft and the apparatus main body. 7. The conductive means is a conductive elastic member interposed between the sheet storage means and the apparatus main body, and elastically deforms when the sheet storage means is attached to the apparatus main body, and thus the sheet. The sheet feeding device according to claim 6, wherein the storage means is biased in the pull-out direction. 8. The apparatus main body has a lock means for locking the sheet storage means at a mounting position, and the elastic means urges the sheet storage means to position the sheet storage means. The sheet feeding device according to claim 7, further comprising a reference surface. 9. The elastic member is a compression coil spring, one end of which is fixed to the main body of the apparatus and the other end of which is provided so as to be in pressure contact with a rotation shaft of the sheet storage means. The sheet feeding device according to item 7. 10. A sheet feeding device according to claim 6, and an image forming unit for forming an image on a sheet fed by the sheet feeding device. An image forming apparatus characterized by.