JP3120944B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a laser printer or a facsimile machine using a roller transfer system, and more particularly to a detachable mounting of a photosensitive drum unit, a cleaning unit or a developing unit built in the apparatus. The present invention relates to an image forming apparatus that can be easily performed.

[0002]

2. Description of the Related Art In recent years, in a transfer apparatus using a roller transfer system, a transfer roller is arranged so that a peripheral surface thereof is closely opposed to a surface of a photosensitive drum in a non-contact manner.
A so-called non-contact type roller transfer system has been developed which eliminates toner contamination on the peripheral surface of the transfer roller and suppresses the occurrence of image unevenness as much as possible.

In such a transfer device of the non-contact type roller transfer system, as means for maintaining a gap between the photosensitive drum and the transfer roller, for example, as shown in FIG. Gap holding rollers 3 formed at both ends with a diameter larger than the transfer roller 31.
3, the circumferential surface of the gap holding roller 33 is brought into rolling contact with the surface of the photosensitive drum 34, thereby forming a constant gap C between the circumferential surface of the transfer roller 31 and the drum surface. Things are known.

Incidentally, in a copying machine or the like, a clamshell structure in which an upper structure is configured to be openable and closable so that a paper passage can be opened is widely used. In the apparatus having the transfer device of the non-contact type roller transfer system, the gap holding roller is in contact with the drum when the upper shell is closed.

That is, the transfer roller 31 shown in FIG.
Roller shaft 32 for supporting a pair of gap maintaining rollers 33
The transfer roller unit rotatably supported by the housing 35 is urged upward by a spring (not shown) provided between the housing 35 and the base of the machine main body, whereby the upper shell is closed. In this configuration, the peripheral surface of the gap holding roller 33 is configured to be in rolling contact with the drum surface.

[0006]

However, according to such a structure, the gap holding roller 33 is always in contact with the drum 34 when the shell is closed. Therefore, if the shell is not opened, the drum unit and the drum unit are not opened. It is impossible to attach / detach the cleaning unit, the developing unit, and the like provided in the periphery in the direction of the white arrow.

[0007] For this reason, when it becomes necessary to repair or replace the above-mentioned drum unit or the like, it is necessary to open the clamshell every time, and there is a problem in workability. A great deal of labor is also required due to the installation location, unfamiliarity of the user, and the like. Such inconvenience can also occur in a conventional contact-type roller transfer system in which the transfer roller itself contacts the photosensitive drum.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. In an image forming apparatus using a roller transfer system, a drum unit, a cleaning unit, An object of the present invention is to make it possible to attach and detach a developing unit and the like.

[0009]

According to the present invention, a transfer roller shaft and a housing for rotatably supporting the transfer roller shaft are provided, and a peripheral surface of a roller body mounted on the transfer roller shaft is provided. A transfer roller unit urged upward by a spring so as to be in rolling contact with the surface of the photosensitive drum is disposed in the machine body, and a front cover for opening and closing the housing of the transfer roller unit and the front side of the machine body. In conjunction with opening and closing of the front cover, when the front cover is opened, the transfer roller unit is forced against the urging force of the spring until the roller body separates from the photosensitive drum surface. Roller release releasing means for lowering is interposed.

[0010]

[0011] Then, while interposing the spring between the housing and the machine body for supporting the transfer roller shaft, a lever member having a slant cam at the rear end with the front end is interlocked to the front cover, The cam follower provided in the housing constitutes a roller rolling release unit, and the lever body moves in the thrust direction with the opening movement of the front cover, so that the cam interferes with the cam follower and lowers the housing. be able to.

[0012]

[0013]

According to the action-described structure, when opening the front cover, to advance the lever body, the slope cam provided on the lever body with the can which, interfere with the cam follower provided in the housing, the transfer roller unit Spring The roller is forcibly lowered against the urging force of the roller, whereby the peripheral surface of the roller body is separated from the surface of the photosensitive drum, and the drum can be removed. Also, by removing the drum,
Removal of surrounding cleaning units and developing units
Will be possible.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic copying machine will be described below with reference to the drawings. FIG. 1 schematically shows a main part in the copying machine. In this figure,
Reference numeral 1 denotes a photosensitive drum provided in a machine main body (not shown). Around the photosensitive drum 1, a main charger 2, which is a corona discharger, a developing unit 3, a transfer device 4, and a cleaning unit 5, are arranged in the order of rotation of the drum 1.

An exposure unit 6 is provided between the main charger 2 and the developing unit 3, and a charge removing unit 7 is provided between the cleaning unit 5 and the main charger 2. 30
Is a paper feed roller for feeding the paper P between the drum 1 and the transfer device 4 at a predetermined timing, and a paper feed device (not shown)
It is arranged on the terminal side of. Although not shown, the copying machine of the present embodiment has a clamshell structure in which the upper structure can be opened and closed via a hinge at a paper passing path passing between the drum 1 and the transfer device 4. I have.

In the copying machine having the above configuration, the surface of the photosensitive drum 1 is charged by the corona discharge action of the main charger 2. On the charged drum surface, an electrostatic latent image of an original image read by an optical system (not shown) provided in the upper part of the machine main body is formed in the exposure unit 6, and then the electrostatic latent image is formed by the developing unit 3. The charged toner is attached to the electro-latent image to form a toner image of the original image. During this time, the paper P is fed between the drum 1 and the transfer device 4 at a predetermined timing by the paper feed device, and the transfer device 4 operates as described later in detail, and the toner image on the drum surface is transferred to the paper P. Is done.

After the end of the transfer, the toner remaining on the drum surface is scraped off by a cleaning blade 5a provided in the cleaning unit 5, and further, the drum surface is discharged in the charge removing section 7 to prepare for the next charging. Further, the paper P on which the toner image has been transferred is heated and pressed by a fixing device (not shown) disposed downstream of the transfer device 4 in the paper transport direction in the machine main body. The sheet is fixed on the sheet P and finally discharged from the machine body.

FIGS. 2 to 4 show a specific configuration of the transfer device 4. In these figures, reference numeral 8 denotes a transfer roller having a function of guiding the paper P, which is made of a conductive material such as copper, aluminum, iron, or the like, or a conductive resin material kneaded with carbon or the like. An outer cylinder having an elastic cylinder such as a sponge is fitted around the outer periphery of the tubular body, and has a length including the image forming area of the drum 1.

The transfer roller 8 has a peripheral surface facing the drum surface below the drum 1 and is arranged in a non-contact state with the drum 1. That is, the roller shaft 9 on which the transfer roller 8 is mounted is rotatably supported at both end portions by a bearing member 12 fastened to the front and rear wall portions 10a of the housing 10 having a U-shaped cross section by screws 11. . Further, at both ends of the roller shaft 9 protruding outside the bearing member 12, gap maintaining rollers 13 each having a slightly larger diameter than the transfer roller 8 are mounted.

At both ends of the housing 10, there are provided brackets 14 extending from the front and rear wall portions 10a, respectively.
Has been erected. Both ends of the support shaft 15 are pivotally supported by side plates (not shown) provided on both front and rear sides of the machine main body, whereby the housing 10 is pivotally supported about the support shaft 15 so as to be vertically swingable. Is what is done. A spring 17 composed of a compression coil spring is interposed between the housing 10 and the base 16 of the machine main body, whereby the housing 10 is biased upward by a spring.

In the transfer roller unit U having such a configuration, the housing 10 is urged upwardly around the support shaft 15 by the urging force of the spring 17 so that the housing 10 is pressed against the roller shaft 9 via the bearing member 12. The peripheral surface of the pivotally supported gap holding roller 13 elastically rolls on the drum surface, thereby forming a constant gap C between the peripheral surface of the transfer roller 8 and the drum surface. The gap C is specifically set to about 0.5 mm.

A pre-transfer guide 18 for guiding the sheet P to the surface of the drum is provided near the upstream side of the transfer roller 8 in the sheet conveying direction. The pre-transfer guide 18 has a long front and rear guide plate 18a which is inclined upward from the upstream side to the downstream side in the sheet transport direction. Brackets 18b provided on both sides of the guide plate 18a are provided between front and rear side plates of the machine main body. And is pivotally supported by a spring (not shown) interposed between the bracket 18b and the base 17 so as to be swingable up and down.

Above the pre-transfer guide 18, a pre-transfer roller 20 for feeding the sheet P to the drum surface at the same speed as the movement speed of the drum surface has a small gap between the pre-transfer roller 20 and the upper surface of the guide plate 18a. It is arranged. The roller shaft end of the pre-transfer roller 20 is rotatably supported by a pre-transfer roller bearing 12b provided on the tip side of the transfer roller bearing 12a of the bearing member 12 described above.

The pre-transfer roller 20 rotates in the forward direction with respect to the drum 1 and feeds the paper P at the same speed as the peripheral speed of the drum 1. It is configured to be rotationally driven by the output of a motor via a known drive transmission system.

In the transfer device 4 of the present embodiment configured as described above, the paper P fed from the paper feeder at a predetermined timing is applied to the guide plate 18 of the pre-transfer guide 18.
a and is brought into contact with the surface of the photosensitive drum 1 by being guided to the upper surface.
At this time, the moving speed of the paper P is made the same as the speed of the drum surface by the paper feed roller 30. The leading end of the sheet P advances toward the gap C between the transfer roller 8 and the drum 1 in a state of contacting the drum surface, and the sheet P expands upward with the lower surface supported by the leading end of the guide plate 18a. For this reason,
The upper surface of the sheet P comes into contact with the pre-transfer roller 20, and the conveying force is also given from the pre-transfer roller 20. The paper P moves at the same speed as the drum surface even after the trailing edge of the paper P is released from the paper feed roller 30 by this transport force. Since the lower surface of the sheet P is supported by the leading end of the guide plate 18a and the upper surface is pressed by the pre-transfer roller 20, the upper surface of the sheet P is in close contact with the surface of the photosensitive drum 1 in the gap C due to the stiffness of the sheet itself. I do.

The paper P is the gap C between the transfer roller 8 and the drum 1
, A transfer voltage having a polarity opposite to that of the toner on the drum surface is applied to the transfer roller 8. Thus, the toner image carried on the surface of the photosensitive drum 1 is transferred to the upper surface of the sheet P. The paper P after the transfer is separated from the drum surface and then sent to the fixing device as described above.

In the present embodiment, the pre-transfer roller 20 and the guide plate 18a of the pre-transfer guide 18 are not in contact with each other. However, the pre-transfer roller 20 may be configured to substantially contact the upper surface of the guide plate 18a. Good.

3 and 4, reference numeral 21 denotes an openable and closable front cover disposed on the front side of the machine main body. As shown in FIG. It is configured to open by tilting forward.

Reference numeral 22 denotes a roller rolling release mechanism interposed between the front cover 21 and the housing 10. The roller rolling release mechanism is interlocked with the opening and closing of the front cover 21, and the gap holding roller 13 is opened when the front cover 21 is opened. Is forcibly lowering the transfer roller unit U against the urging force of the spring 17 to a position separated from the drum surface. In the present embodiment, the roller rolling release mechanism 22 is configured as follows. .

That is, L
A cam follower piece 23 having a U-shape is integrally formed.
On the other hand, a connecting rod 24 projects substantially horizontally from the rear side of the front cover 21, and the distal end of the connecting rod 24 is connected to one end of a link member 25. The other end of the link member 25 is connected to a base end of a release lever 26 that slides on the upper surface of the cam follower piece 23. Further, a slope cam 27 descending rearward is formed on the lower surface of the distal end portion of the release lever 26. Also, a release lever guide 2 formed to cover the release lever 29
9 is fixedly installed on the base 16 of the machine body.

In the roller rolling release mechanism 22 configured as described above, when the front cover 21 is closed, FIG.
As shown in FIG. 3A, the cam follower piece 23 of the housing 10 is released by the urging force of the spring 17 to release lever 26.
And the inclined cam 27 is located at the rearmost end which does not interfere with the cam follower piece 23.

When it is necessary to attach or detach the drum 1, the developing unit 3 or the cleaning unit 5 from the closed state of the cover, for example, when the front cover 21 is pulled toward the user, the connecting rod 24 is opened with the opening operation. Moves forward, the release lever 26 is pulled forward via the link member 25 and moves in the thrust direction, whereby the inclined cam 27 interferes with the cam follower piece 23. At this time, since the upward movement of the release lever 26 is restricted by the upper surface contacting the inner surface of the release lever guide 29, the inclined cam 27 pushes down the cam follower piece 23. Therefore, the cam follower piece 23 descends vertically along the inclined cam 27 against the urging force of the spring 17 as shown in FIG.

Then, the entire transfer roller unit U is forcibly lowered by the vertical lowering of the cam follower piece 23, whereby the peripheral surface of the gap holding roller 13 is separated from the drum surface, and the drum 1 and the gap holding roller 13 are separated from each other. Is released. In this state, the drum 1
Since the gap holding roller 13 does not interfere with the drum 1, the drum 1 can be freely attached and detached. Further, by removing the drum, the developing unit 3 and the cleaning unit 5 around the drum can be attached and detached.

In this embodiment, the gap holding roller 13
Although the roller contact release mechanism 22 corresponding to the non-contact type transfer device using the above has been described, the present invention also applies to a known roller transfer type in which the transfer roller 8 directly contacts the drum 1 in the present embodiment. It is needless to say that the drum 1 and the like can be attached and detached without opening the clamshell by the same configuration as the mechanism.

[0035]

As described above, according to the present invention, between the housing of the transfer roller unit and the front cover for opening and closing the front side of the machine main body, the front cover is opened and closed. When the roller is opened, the roller cover releasing means for forcibly lowering the transfer roller unit against the urging force of the spring is interposed until the roller body separates from the peripheral surface of the photosensitive drum. When the most basic operation of opening the front cover is performed, the transfer roller unit moves down in conjunction with the opening movement of the front cover, and the peripheral surface of the roller body can be separated from the surface of the photosensitive drum. It is possible.

Further, by the lever member with the opening motion of the front cover is moved in the thrust direction, the cam is configured so as to lower the housing interferes with the cam follower, the lever body in the front cover opening-time The transfer roller unit can be smoothly and smoothly lowered with the advance operation, and the structure is simple enough to add a lever body.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a configuration of a copying machine according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a transfer device.

FIG. 3 is a perspective view showing a transfer roller unit and a roller rolling contact release mechanism.

FIG. 4 is a longitudinal sectional view thereof.

FIG. 5 is a schematic side view showing the operation of the roller rolling release mechanism in order.

FIG. 6 is an enlarged view of a main part showing an example of a conventional transfer device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 8 transfer roller 9 roller shaft 10 housing 13 gap maintaining roller 16 base of machine body 17 spring 21 front cover 22 roller rolling release mechanism 23 cam follower piece 26 release lever 27 inclined cam 29 release lever guide C gap U transfer roller unit

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Kodera 1-2-28 Tamazo, Chuo-ku, Osaka-shi Inside Mita Kogyo Co., Ltd. (72) Inventor Hiroki Morishita 1-2-28 Tamatsuzo, Chuo-ku, Osaka-shi Mita Kogyo Co., Ltd. (72) Inventor: Yasuhiko Moriuchi, 1-2-2, Tamazo, Chuo-ku, Osaka-shi Mita Kogyo Co., Ltd. 72) Inventor Naoyuki Ishida 1-2-28 Tamazo, Chuo-ku, Osaka-shi Mita Kogyo Co., Ltd. (56) References JP-A-63-186282 (JP, A) JP-A-7-302007 (JP, A) Kaihei 4-11560 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 21/16 G03G 15/02

Claims (1)

(57) [Claims] A transfer roller shaft; and a housing rotatably supporting the transfer roller shaft. The transfer roller shaft is rotatably supported by a spring so that a peripheral surface of a roller body mounted on the transfer roller shaft is in contact with a surface of a photosensitive drum. The biased transfer roller unit is disposed in the machine body, and between the housing of the transfer roller unit and a front cover that opens and closes the front side of the machine body, interlocked with the opening and closing of the front cover. At the time of opening the front cover, a roller rolling contact release unit for forcibly lowering the transfer roller unit against the urging force of the spring is interposed to a position where the roller body is separated from the photosensitive drum surface , and the spring is , Transcription low
Between the housing that supports the shaft and the machine body.
On the other hand, the roller rolling release
Latches that are interlocked and have a sloped cam at the rear end
A bar body, a cam follower provided in the housing,
The lever body thrusts with the opening of the front cover
The cam interferes with the cam follower by moving in the direction
An image forming apparatus configured to move down the housing .