JP2802410B2 - 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 a mechanism for pressing a transfer roller against a photosensitive member via an intermediate transfer member in an image forming apparatus such as a full-color copying machine having an intermediate transfer member.

[0002]

2. Description of the Related Art As shown in FIGS. 6 and 7, in a conventional full-color copying machine, when a deteriorated belt-shaped intermediate transfer body 1 is replaced with a new one, a toner image is transferred from a photoconductor 2 to the intermediate transfer body 1. Since the transfer roller 3 is in pressure contact with the photoreceptor 2 via the intermediate transfer member 1, it is necessary to release the pressure contact and replace the intermediate transfer member 1 and, after the replacement, press the photoreceptor 2 again.

The transfer roller 3 is rotatably supported by a transfer roller unit 4, as shown in FIGS. 6 and 7, and the transfer roller unit 4 is rotatably supported around a shaft 4a. A switching lever unit 5 for pressing and separating the transfer roller 3 from and against the photosensitive member 2 is rotatably supported around a shaft 5a. The switching lever unit 5 includes a compression spring therein. In the drawing, reference numeral 5b denotes a rolling roller that rolls below the transfer roller unit 4.

[0004] The replacement of the intermediate transfer member 1 is performed as shown in FIG.
The switching lever unit 5 is manually tilted around the shaft 5a from the state where the transfer roller 3 is pressed against the photosensitive member 2 as shown in FIG. Then, the transfer roller unit 4 rotates downward around the shaft 4a by its own weight, and as shown in FIG. 6, the transfer roller 3 is separated from the photosensitive member 2, and the intermediate transfer member 1 is slackened.

During this time, the intermediate transfer member 1 is replaced, and after the replacement,
The switching lever unit 5 is manually lifted around the shaft 5a,
As a result, the transfer roller unit 4 rotates around the shaft 4a and is lifted. Then, the intermediate transfer member 1 is also lifted while being stretched, and the transfer roller 3 is pressed against the photosensitive member 2 via the intermediate transfer member 1 to complete the replacement operation.

[0006]

However, in the above-mentioned prior art, the switching lever unit 5 is lifted by one manual operation, and the transfer roller 3 is rotated via the intermediate transfer body 1 by the rotation of the transfer roller unit 4. 5 kg / cm in the switching lever unit 5 for pressing against the photoreceptor 2
^Two strong spring pressures are applied to photoconductor 2, intermediate transfer body 1,
These members are applied to the transfer roller unit 4 at a stretch, and there is a possibility that these members may be damaged.

As shown in FIGS. 8 and 9, each roller 6 around which the intermediate transfer member 1 is wound
A meandering-preventing silicon bead (bank) 7 is formed to fit into the grooves a, 6b, 6c (see FIG. 6). However, if the intermediate transfer body 1 is pressed against the photoreceptor 2 while being attached obliquely when the intermediate transfer body 1 is replaced, the intermediate transfer body 1 rotates while meandering off the groove of the roller and the belt end. May be damaged. Further, although the timing detection hole 9 is formed in a part of the reinforcing tape 8 of the intermediate transfer body 1, when the intermediate transfer body 1 meanders, timing detection failure occurs.

SUMMARY OF THE INVENTION In view of the above, the present invention provides an image forming apparatus that gradually presses an intermediate transfer member against a photosensitive member to suppress damage to peripheral members and meandering of the intermediate transfer member.

[0009]

According to a first aspect of the present invention, there is provided a rotatable intermediate transfer member 21 onto which a toner image formed on a photosensitive member 14 is transferred, as shown in FIG. When the transfer roller 26 for transferring the toner image from 14 to the intermediate transfer body 21 and the intermediate transfer body 21 are exchanged,
When the intermediate transfer member 21 is mounted, the transfer roller 26 is pressed against the photosensitive member 14 via the intermediate transfer member 21, and when the intermediate transfer member 21 is removed, the transfer roller 26 is separated from the photosensitive member 14 by pressing and separating means 70. In the image forming apparatus provided with
The press-contact / separation unit 70 is provided to move the intermediate transfer body 21
And a rotatable cam 4 for gradually applying pressure to the pressing portion 41 in the pressing direction.
2 and a cam driving means 43 for driving the cam 42. The cam driving means 43 uses the driving force of the intermediate transfer body driving section 23 when the intermediate transfer body 21 is idling before the start of image formation. And a switching unit 60 for transmitting the driving force to the cam 42 when the intermediate transfer body 21 is replaced and separating the driving force to the cam 42 during image formation.

According to a second aspect of the present invention, the cam driving means 43 is provided with a speed reduction mechanism 55 for reducing the driving force from the intermediate transfer body driving section 23.

[0011]

According to the first and second aspects of the present invention, after replacing the intermediate transfer body 21 by maintenance or the like,
The operation of pressing the transfer roller 26 against the photoreceptor 14 via the intermediate transfer body 21 is as follows. First, the pressing unit 41 is manually lifted, and the transfer roller 26 is pressed with a certain pressure to the intermediate transfer body 21.
Is pressed into contact with the photoreceptor 14. This state is shown in FIG.

Here, when the intermediate transfer member driving section 23 is driven to idle the intermediate transfer member 21, the driving force is transmitted to the cam 42 by the switching means 60, and the cam 42 is slowly rotated by the speed reduction mechanism 55. . Due to the rotation of the cam 42, the pressing portion 41 gradually presses the transfer roller 26, and the transfer roller 26 is pressed against the photosensitive member 14 at a predetermined pressure via the intermediate transfer member 21. This state is shown in FIG.

As described above, since the transfer roller 26 is gradually pressed by the rotation of the cam 42 while the intermediate transfer member 21 is idling, the impact on the photosensitive member 14, the intermediate transfer member 21, the transfer roller 26 and the like is reduced. Then, meandering of the intermediate transfer body 21 is suppressed.

[0014]

FIG. 1 is a perspective view of a press-contact / separation means showing one embodiment of the present invention, FIG. 2 is an overall configuration diagram of a copying machine of this embodiment, and FIG.
4 is a partial cross-sectional view of the pressure contact / separation means showing a state before pressurization, FIG.
FIG. 5 is a partial cross-sectional view of the pressure contact / separation means showing a state at the time of pressurization.
9 is a flowchart of an operation of replacing an intermediate transfer member.

First, the overall configuration of the full-color copying machine according to the present embodiment will be described with reference to FIG. A transparent document table 10 is provided on the upper surface of the machine frame. Also, the original table 10
An exposure optical system 11 is disposed below the document. The exposure optical system 11
A light source lamp 13a for irradiating light to the light source 2, a plurality of reflecting mirrors 13b for guiding reflected light from the document 12 onto the photoreceptor 14 as indicated by a dashed line, for example, and an imaging lens 13c disposed on the optical path. , Red, green and blue color separation filters 13d.

On the optical axis of the above-mentioned exposure optical system 11, there is provided a drum-shaped photoconductor 14 made of an organic photoconductor (OPC) to which an optical image subjected to exposure scanning is irradiated. Paper feed cassettes 16 and 17 containing transfer papers 15 are disposed on the paper feed direction side of the paper 14. Paper feed rollers 18 and 19 are provided on the upper surfaces of these paper feed cassettes 16 and 17, respectively. These paper feed rollers 18 and 19 transfer the transfer paper 15 from the paper feed cassettes 16 and 17. The sheet is discharged and sent to the intermediate transfer member 21.

A timing roller 22 is provided on the side of the paper feed rollers 18 and 19 toward the intermediate transfer member 21. The timing roller 22 is rotated in synchronization with the intermediate transfer member 21. It has become so. Also,
The intermediate transfer body 21 is driven to rotate by an intermediate transfer body driving unit 23. The intermediate transfer body driving unit 23 drives the first roller 24a via first to third rollers 24a, 24b, and 24c via gears and belts. And a drive motor 25 for driving.

A pair of first transfer rollers 26 for transferring the toner image on the photosensitive member 14 to the intermediate transfer member 21 is disposed on the back side of the intermediate transfer member 21 which is pressed against the photosensitive member 14. The first transfer roller 26 can be pressed and separated from the photoreceptor 14 via the intermediate transfer member 21 by pressing and separating means 70.

A second transfer roller 27 is disposed on the surface of the intermediate transfer member 21 at the position where the third roller 24c is disposed. Then, on the delivery side of the second transfer roller 27,
Release plate 28, transport belt 29, and fixing device 30
Are arranged in this order.

A charging charger 31 for charging the photoreceptor 14 and a discharge lamp 32 for discharging the photoreceptor 14 are provided around the outer periphery of the photoreceptor 14. A cleaning device 33 as cleaning means for removing toner remaining on the photoconductor 14 is provided. Further, a developing tank 34 for black-and-white is provided on the upper portion thereof in a state of not contacting the photoconductor 14.
And color developing tanks 35 to 37 are independently provided, and yellow, magenta, and cyan color developers are individually accommodated in the color developing tanks 35 to 37. .

The first transfer roller 26 is, as shown in FIG.
The switching position can be switched between a pressing position in which the photosensitive member 14 is pressed through the intermediate transfer member 21 via the intermediate transfer member 21 and a separating position separated from the photosensitive member 14, and is rotatably supported by the transfer roller unit 40. The transfer roller unit 40 has both ends in the axial direction rotatably supported by a frame of the copying machine main body H via a shaft 40a.

As shown in FIG. 1, the pressure contact / separation means 70 presses the transfer roller unit 40 in the direction of the photoreceptor 14 with a certain amount of pressure (switching lever unit) 41.
And a rotatable cam 42 for gradually applying pressure to the transfer roller unit 40 in the pressing direction, and a cam driving means 43 for driving the cam 42.

As shown in FIG. 1, the switching lever unit 41 includes a pair of push-up members 44 for pushing up the transfer roller unit 40 when the first transfer roller 26 shifts from the separated position to the pressure-contact position, and the lower portions of the two push-up members 44. Connecting rod 4 for connecting
5 and a lever 46 fixed to the end of the connecting rod 45 on the front side of the copying machine main body H.

As shown in FIGS. 3 and 4, the push-up body 44 is provided with a rolling roller 47 for pressing the lower surface of the transfer roller unit 40 while rolling, and a rolling roller support for rotatably supporting the rolling roller 47. The member 48 and the rolling roller support member 48
And a compression spring 50 that urges the rolling roller support member 48 upward.

The cams 42 are arranged below the push-up bodies 44 and are fixed to a cam shaft 42a rotatably supported by a frame of the copying machine main body H. The upper portion of the cam 42 abuts on a bottom plate 48a slidably mounted on the push-up body 49, and a compression spring 50 is interposed between the bottom plate 48a and the rolling roller support member 48. A connecting rod 45 is rotatably fitted to the cam shaft 42a, and one end of the copying machine main body H on the rear side is connected to the cam driving means 43.

The cam drive means 43 is connected to the drive motor 25 of the intermediate transfer body drive unit 23 via a speed reduction mechanism 55. The speed reduction mechanism 55 is connected to the drive motor 2 as shown in FIG.
5 includes a drive unit-side gear 57 to which drive force from the drive unit 5 is transmitted via a drive belt 56, and a main driving gear 58 that meshes with the drive unit-side gear 57. The gear ratio is set to 1: 2. The rotation speed from 25 is reduced to half and the camshaft 4
2a.

The main driving gear 58 is connected to a driven gear 59 fixed to one end of the cam shaft 42a via a switching means 60. The switching means 60 is an electromagnetic clutch.
When the intermediate transfer member 21 is idled in the simulation function in which a part of the machine is simulated before the copy operation at the end of the exchange operation of the intermediate transfer member 21 while the main drive gear 58 and the driven gear 59 are separated. , And is driven by the output signal to connect the driving gear 58 and the driven gear 59.

The operation of the full-color copying machine having the above configuration will be described below. First, when a copy start switch (not shown) is pressed, a copy mode is executed.
This copy mode has a copy cycle in which yellow, magenta, and cyan are developed and transferred to the intermediate transfer body 21, respectively. When the copy mode is executed,
First, a yellow copy cycle is executed.

That is, light is emitted from the light source lamp 13a to the original 12 placed on the original placing table 10, and exposure scanning is performed. The reflected light from the original 12 is reflected by the reflecting mirror 13.
b and the color separation filter 13 via the imaging lens 13c
d, and is separated for each color component by the color separation filter 13d.

The light for each color component transmitted through each color filter of the color separation filter 13d in the above exposure scan is irradiated onto the photoreceptor 14 uniformly charged by the charging charger 31.
The photoreceptor 14 is exposed at the portion A. On the photoconductor 14, a yellow electrostatic latent image corresponding to the image of the document 12 is formed.

Thereafter, each of the above-described electrostatic latent images is developed with a developer supplied from a developing magnet roller in a portion opposite to a developing tank 35 having a yellow developer which is a complementary color of the color separation filter 13d. It is visualized and becomes a toner image. Then, the toner image is transferred to the intermediate transfer member 21 pressed against the photoconductor 14 by applying a high voltage to the first transfer roller 26.

When the yellow copy cycle is completed, the photosensitive member 14 is cleaned by the cleaning device 33 and is discharged by the discharge lamp 32. Then, the magenta and cyan toner images are transferred to the intermediate transfer body 21 in the same copy cycle as described above.

When each copy cycle described above is executed,
The toner image for each color component is transferred to the same position on the intermediate transfer member 21 by the first transfer roller 26, and a completed toner image is formed by overlapping the toner images for each color component. become.

On the other hand, the transfer paper 15 stored in the paper feed cassettes 16 and 17 is fed one by one to the timing roller 22 by the paper feed rollers 18 and 19,
2 transports the transfer paper 15 between the intermediate transfer member 21 and the second transfer roller 27 in synchronization with the intermediate transfer member 21. After the toner image on the intermediate transfer member 21 is transferred by the second transfer roller 27, the transferred transfer paper 15 is separated from the intermediate transfer member 21 by the separation plate 28, and is introduced into the fixing device 30 by the transfer belt 29. . Then, after the color toner image is fixed on the transfer paper 15 and discharged outside, one copy mode is completed.

Then, a maintenance person periodically performs inspection for each member and maintenance for replacement due to deterioration.

When the intermediate transfer member 21 is replaced at this time, when the lever 46 is pushed down around the connecting rod 45, the transfer roller unit 40 is rotated downward by its own weight around the shaft 40a, and the first transfer roller 26 is pressed against the shaft 40a. Then, the pressure contact is released and the tension of the intermediate transfer body 21 is removed, and then the intermediate transfer body 21 is replaced.

When the new intermediate transfer member 21 is placed over the rollers 24a, 24b, 24c and the lever 46 of the switching lever unit 41 is manually lifted in the direction B in FIG. 1, the rolling roller 47 of the push-up member 44 is rotated. Roll the transfer roller unit 40 to the lower side while rolling the lower surface of the transfer roller unit 40.
, The first transfer roller 26 is lifted.
The first transfer roller 26 is connected to the compression spring 5 in the push-up body 49.
0 and the photosensitive member 14 via the intermediate transfer member 21
At a pressure of 3 kg / cm ² . At this time, the cam 42 is at the position shown in FIG.

Here, by pressing a key for starting the simulation function, the drive motor 25 is driven, and the intermediate transfer body 21 is rotated, and at the same time, the electromagnetic clutch 60 is operated to bring the main driving gear 58 and the driven gear 59 into a connected state. ,
The cam 42 rotates slowly at half the rotation speed of the drive motor 25.

The rotation of the cam 42 pushes up the rolling roller support member 48 via the bottom plate 48a, and the rolling roller 47 gradually presses the transfer roller unit 40 upward, as shown in FIG. 26 is the intermediate transfer member 21
Is pressed to the photoreceptor 14 at a pressure of 5 kg / cm ² while maximizing the pressure, and a normal transferable state is obtained.

Thus, after the replacement of the intermediate transfer member 21,
When the intermediate transfer body 21 is pressed against the photoconductor 14, first, the first transfer roller 26 is operated by operating the lever 46.
Is pressed against the photoreceptor 14 at a pressure of 3 kg / cm ² through the intermediate transfer member 21, and then the pressure is gradually increased to 5 kg / cm ² by the rotation of the cam 42 during the idle rotation of the intermediate transfer body 21. The photoconductor 14, the intermediate transfer member 21, and the first transfer roller 26
And the like can be reduced, and damage can be suppressed.

Even when the intermediate transfer member 21 is mounted obliquely, since the intermediate transfer member 21 is gradually pressed while being idlely rotated, tension is applied to the intermediate transfer member 21 so that the intermediate transfer member 21 is placed in a natural position. As a result, the beads of the intermediate transfer body 21 fit into the grooves of the respective rollers, and meandering can be corrected during rotation, thereby suppressing meandering.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

For example, a unit in which the transfer roller unit 40 and the switching lever unit 41 are integrated may be provided, and this unit may be pressed against the photosensitive member by a cam or the like.

[0044]

As is apparent from the above description, according to the first and second aspects of the present invention, when the transfer roller is pressed against the photosensitive member via the intermediate transfer member after the replacement of the intermediate transfer member, the intermediate transfer member is emptied. Since the pressure is gradually increased by the rotation of the cam while being rotated, the impact on the photoreceptor, the intermediate transfer member, the transfer roller, and the like can be reduced and the breakage can be suppressed, as compared with the conventional case of pressing and fixing at once.

Further, even when the intermediate transfer member is mounted obliquely, since the intermediate transfer member is gradually pressurized while rotating idly, meandering can be corrected during rotation, and meandering can be suppressed. There is an excellent effect that it can be done.

[Brief description of the drawings]

FIG. 1 is a perspective view of a pressure contact / separation means showing one embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a copying machine according to the present embodiment.

FIG. 3 is a partial cross-sectional view of a pressure contact / separation unit showing a state before pressurization.

FIG. 4 is a partial cross-sectional view of a pressure contact / separation unit showing a state at the time of pressurization

FIG. 5 is a flowchart of an intermediate transfer body replacement operation.

FIG. 6 is a configuration diagram showing a conventional intermediate transfer member separated from a photosensitive member.

FIG. 7 is a configuration diagram showing a conventional intermediate transfer member in a state of being pressed against a photosensitive member.

FIG. 8 is a plan view of an intermediate transfer member.

FIG. 9 is a sectional view taken along the line DD in FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 14 Photoreceptor 21 Intermediate transfer body 23 Intermediate transfer body driving part 26 Transfer roller 41 Pressing part 42 Cam 43 Cam driving means 55 Reduction mechanism 60 Switching means 70 Pressure contact / separation means

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/16

Claims (2)

(57) [Claims] An exchangeable intermediate transfer member on which a toner image formed on a photosensitive member is transferred; a transfer roller for transferring a toner image from the photosensitive member to the intermediate transfer member; and an intermediate transfer member. When the intermediate transfer member is mounted, the transfer roller is pressed against the photosensitive member via the intermediate transfer member, and the image forming apparatus is provided with pressure contact and separation means for separating the transfer roller from the photosensitive member when removing the intermediate transfer member. A pressing unit for pressing the intermediate transfer body in the direction of the photoreceptor, a rotatable cam for gradually applying pressure to the pressing unit in the pressing direction, and a cam for driving the cam. A driving unit for transmitting the driving force to the cam when the intermediate transfer body is replaced by using the driving force of the intermediate transfer body driving unit when the intermediate transfer body is idle before starting the image formation. To the cam during image formation. Image forming apparatus characterized by switching means for disconnecting the power is provided. 2. The image forming apparatus according to claim 1, wherein the cam driving means is provided with a speed reduction mechanism for reducing the driving force from the intermediate transfer body driving unit.