JPH05289536A - Photosensitive body and intermediate transfer body driving device for electrophotographic device - Google Patents

Abstract

PURPOSE:To realize a color electrophotographic device in which speed variation caused by backlash between an intermediate transfer body driving gear and a photosensitive body driving gear is prevented, and color slurring and uneven color are hardly caused. CONSTITUTION:The diameter of a photosensitive body driving roller 2 is set a little larger than a designed value and the diameter of an intermediate transfer body driving roller 5 is set a little smaller than a designed value, so that the circumferential speed of a photosensitive body 1 is a little higher than the circumferential speed of an intermediate transfer body 4. By allowing frictional force F to be generated between the photosensitive body 1 and the intermediate transfer body 4 because of the difference of circumferential speed to act on the roller 2 as load, driving force is stably transmitted from the intermediate transfer body driving gear 5a to the photosensitive body driving gear 2a while the gear 2a and the gear 5a are always meshed with each other in a fixed direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus for forming a color image by forming an electrostatic latent image corresponding to each color on a photosensitive member by an exposing means and superposing the toner images on each other.

[0002]

2. Description of the Related Art In recent years, a color electrophotographic apparatus forms toner images of different colors on a photoconductor in sequence, multiple-transfers the toner images of the respective colors onto an intermediate transfer body, and forms a toner image in which the respective colors overlap. A method of collectively transferring onto a transfer material has come to be used.

A conventional color electrophotographic apparatus will be described below. 2 is an overall configuration diagram of a conventional color electrophotographic apparatus, and FIG. 3 is a side view of a photoconductor / intermediate transfer member driving apparatus of the conventional color electrophotographic apparatus. 2 and 3
In the figure, reference numeral 1 denotes a belt-shaped photoconductor in which a photosensitive layer is applied to the surface of a polyester film having a closed loop, and a photoconductor drive roller 32 disposed inside the photoconductor 1
The photoconductor driven roller 3 is rotatably stretched and supported so as to have a vertical plane portion, and a predetermined tension is applied. Further, a photoconductor driving gear 32 a for driving the photoconductor driving roller 32 is provided at an end of the photoconductor driving roller 32. Reference numeral 4 denotes a belt-shaped intermediate transfer member having a closed loop formed of a material having a predetermined electric resistance, which is rotated by an intermediate transfer member driving roller 35 and an intermediate transfer member driven roller 6 arranged inside the intermediate transfer member 4. It is stretched and supported as much as possible and a predetermined tension is applied. Further, an intermediate transfer member driving gear 35 a for driving the intermediate transfer member driving roller 35 is provided at an end portion of the intermediate transfer member driving roller 35. further,
Photoconductor drive roller 32 and intermediate transfer body drive roller 35
Is set so that the peripheral speeds of the photoconductor 1 and the intermediate transfer member 4 are equal. Reference numeral 7 is a drive motor for rotating the photoconductor 1 and the intermediate transfer body 4, and the drive force is transmitted to the intermediate transfer body drive roller 35 by the drive gear 7a. 8
Is urged by an intermediate transfer roller so as to press the intermediate transfer body 4 from the inside of the intermediate transfer body 4 to the photosensitive body driving roller 32 via the photosensitive body 1, and the intermediate transfer body 4 and the surface of the photosensitive body 1 are Are contacted in an arc shape with a predetermined width and pressure.

The operation of the color electrophotographic apparatus having the photoconductor and the intermediate transfer member constructed as described above will be described below.

First, the photosensitive member drive roller 32 and the intermediate transfer member drive roller 35 are driven by the drive motor 7,
The photoconductor 1 and the intermediate transfer member 4 are rotated in the A and B directions, respectively. Next, the surface of the photoconductor 1 is uniformly charged by the charger 9, and first, in synchronization with the slit (not shown) provided in the intermediate transfer body 4, the yellow light emitted from the laser emitting device 10 is emitted. The photoconductor 1 is exposed by laser light according to an electric signal to form a yellow electrostatic latent image. Immediately before the yellow electrostatic latent image reaches the center position of the developing sleeve 13a of the yellow developing device 11a by the rotation of the photoconductor 1 in the direction of arrow A, the developing device separating / connecting means 12 is used to develop the yellow developing device 11a. In the direction of arrow C,
Development sleeve 13 by a doctor blade (not shown)
By applying a developing bias voltage to the developing sleeve 13a to bring the yellow developer 14a whose bristles are regulated to a predetermined thickness on the surface of a into contact with the surface of the photoconductor 1 to develop the developer, a yellow toner is used to develop the image. Be converted.

When the yellow color developing operation is completed, the yellow color developing device 11a is moved by the developing device separating / connecting means 12 in the direction opposite to the photosensitive member 1, that is, in the direction D away from the photosensitive member 1, and the surface of the developing sleeve 13a is moved. At the same time that the yellow toner that has risen up from the surface is separated from the surface of the photoconductor 1, the developing bias voltage is cut off and the developing operation is canceled. During this period, the magenta color developing device 11b, the cyan color developing device 11c, and the black color developing device 11d are connected to the developing sleeves 13b and 13b.
The developer 14b, 14c, 14d of each color regulated to have a predetermined thickness on the surfaces of c and 13d is separated from the photoconductor 1 so as not to contact the surface of the photoconductor 1, and the development bias voltage is also cut off. And the developing operation is canceled. Next, the yellow toner image formed on the photoconductor 1 is pressed by the intermediary transfer roller 8 to which the transfer bias voltage is applied to the intermediary transfer member 4 to the photoconductor driving roller 32 through the photoconductor 1. The image is transferred onto the intermediate transfer member 4. On the other hand, the residual toner remaining on the photoconductor 1 without being transferred to the intermediate transfer body 4 is removed by the photoconductor cleaning device 1.
Removed by 5. Further, the static eliminator 1 is attached to the surface of the photoconductor 1.
LED light or the like is radiated by means of 6 to uniformly remove unnecessary charges to prepare for the next image formation. Hereafter, a series of processes of charging, exposure, development, transfer, cleaning, and static elimination are magenta
The cyan and black colors are sequentially repeated, and toner images of these four colors are layered and formed on the intermediate transfer member 4.

Transfer paper 1 stored in paper cassette 17
The sheet 8 is fed from the sheet cassette 17 to the registration roller 20 by the rotation of the sheet feed roller 19, and is on standby in the registration roller 20 in order to synchronize with the toner image on the intermediate transfer body 4. When the toner image of the fourth color by the black developing device 11d starts to be formed on the intermediate transfer member 4, the registration roller 20 starts to rotate in synchronization with the timing of the start of the transfer, and the standby transfer paper 18 is transferred to the paper. It is conveyed to the roller 21. When the transfer paper 18 is conveyed, the paper transfer roller 21 is pressed against the intermediate transfer body 4 by pressing means (not shown) using a solenoid or the like, and at the same time, a transfer bias voltage is applied to the paper transfer roller 21, and The toner image on the intermediate transfer body 4 is transferred onto the transfer paper 18 while the transfer paper 18 is nipped and conveyed by the paper transfer roller 21 and the intermediate transfer body 4.

On the other hand, the residual toner remaining on the intermediate transfer body 4 without being transferred onto the transfer paper 18 is removed by an intermediate transfer body cleaning device 22 which can be separated and contacted. Finally, the transfer paper 18 on which the toner image has been transferred is conveyed to the fixing device 23, where the toner image is fixed by heat and pressure and is discharged to the outside of the apparatus to complete the image forming operation.

Next, the photosensitive member 1, the photosensitive member driving roller 32,
Operations of the intermediate transfer body 4 and the intermediate transfer body driving roller 35 will be described with reference to FIG.

The driving force of the drive motor 7 is transmitted from the drive gear 7a provided on the drive motor 7 to the intermediate transfer body drive gear 35a provided on the intermediate transfer body drive roller 5, and further via the intermediate transfer body drive gear 35a. Is transmitted to the photoconductor drive gear 32a provided on the photoconductor drive roller 32,
The photoconductor 1 and the intermediate transfer member 4 are rotated in the A and B directions, respectively.

[0011]

In the electrophotographic apparatus using the endless belt-shaped photosensitive member and the endless belt-shaped intermediate transfer member described above, the peripheral speed of the photosensitive member 1 and the intermediate transfer member 4 are as much as possible.
It is necessary to match the peripheral speed of. However, due to variations in the dimensions of the photoconductor drive roller 32 and the intermediate transfer body drive roller 35, the diameter of the photoconductor drive roller 32 becomes smaller than a predetermined dimension, and the intermediate transfer body drive roller 35
In some cases, the peripheral speed of the photosensitive member 1 becomes lower than the peripheral speed of the intermediate transfer member.
On the other hand, a frictional force F acts between the intermediate transfer body 4 and the photoconductor 1, and this frictional force F is applied to the photoconductor drive roller as shown in FIG.
Works in the direction of arrow F. That is, it works in the direction of further increasing the speed of the photoreceptor driving roller. Therefore, the place where the tooth surface of the intermediate transfer member driving gear 35a should originally push the tooth surface of the photosensitive member driving gear 32a, on the contrary, the photosensitive member driving gear 32a pushes the intermediate transfer member driving gear 35a. There is a problem that the meshing becomes unstable and color unevenness and color misregistration occur due to speed fluctuations.

The present invention solves the above-mentioned problems of the prior art. Color unevenness due to speed fluctuations of the photosensitive member and the intermediate transfer member
It is an object of the present invention to provide an electrophotographic apparatus that is less likely to cause color misregistration.

[0013]

In order to achieve this object, the present invention provides an electrophotographic apparatus having a step of transferring a toner image formed on an endless belt-shaped photosensitive member to an endless belt-shaped intermediate transfer member. An apparatus for driving the intermediate transfer body is provided with an intermediate transfer body drive roller for driving the intermediate transfer body by stretching the intermediate transfer body, and a drive source gear fixed on the shaft of the intermediate transfer body drive roller. A device for driving the above-mentioned photoconductor, which is configured by a matching intermediate transfer member drive gear,
The photoconductor drive roller that stretches the photoconductor to drive the photoconductor, and the photoconductor drive gear that is fixed on the shaft of the photoconductor drive roller and meshes with the intermediate transfer body drive gear. By pressing the intermediate transfer member against the photosensitive member on the photosensitive member driving roller, the toner image on the photosensitive member is transferred to the intermediate transfer member, and the peripheral speed of the photosensitive member is slightly lower than the peripheral speed of the intermediate transfer member. It is a fast one.

[0014]

In this structure, since the frictional force generated between the intermediate transfer member and the photosensitive member due to the difference in peripheral speed acts as a load on the photosensitive member driving roller, the intermediate transfer member driving gear and the photosensitive member driving gear are always The driving force is stably transmitted from the intermediate transfer member driving gear to the photosensitive member driving gear while meshing in a fixed direction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The overall structure of the color electrophotographic apparatus in the embodiment of the present invention is the same as that of the conventional example described with reference to FIG. FIG. 1 is a side view of a photosensitive member / intermediate transfer member driving device in a color electrophotographic apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 2 denotes a photoconductor drive roller for driving the photoconductor 1, which has a slightly larger diameter than the design value in order to rotate the photoconductor 1 slightly faster than the intermediate transfer member 4. It is set. Reference numeral 2a is a photoconductor drive gear for driving the photoconductor drive roller 2. 5 is an intermediate transfer member driving roller for driving the intermediate transfer member 4,
In order to rotate the intermediate transfer member 4 slightly slower than the photosensitive member 1, the diameter is set to be slightly smaller than the design value. Reference numeral 5a is an intermediate transfer member drive gear for driving the intermediate transfer member drive roller 5.

Here, the diameter of the photosensitive member driving roller is Da,
When the number of teeth of the photoconductor drive gear is Za, the diameter of the intermediate transfer body drive roller is Db, and the number of teeth of the intermediate transfer body drive gear is Zb, a value satisfying the relationship of Da / Db = Za / Zb is designed as above. It is a value. Therefore, the above-mentioned "to make Da larger than the design value and Db smaller than the design value" means to determine the dimensions of Da and Db so that Da / Db> Za / Zb.

The operation of the color electrophotographic apparatus configured as described above will be described with reference to FIG.

Here, except for the operations of the photoconductor 1, the photoconductor drive roller 2, the photoconductor drive gear 2a, the intermediate transfer body 4, the intermediate transfer body drive roller 5, and the intermediate transfer body drive gear 5a, they are the same as the conventional example. Therefore, the description is omitted.

In FIG. 1, the driving force of the drive motor 7 is transmitted from the drive gear 7a provided on the drive motor 7 to the intermediate transfer body drive gear 5a provided on the intermediate transfer body drive roller 5, and further the intermediate transfer body drive is performed. It is transmitted to the photoconductor drive gear 2a provided on the photoconductor drive roller 2 via the gear 5a, and rotates the photoconductor 1 and the intermediate transfer body 4 in the A and B directions, respectively.

On the other hand, the diameter of the photosensitive member driving roller 2 is set slightly larger than the designed value as described above, and the diameter of the intermediate transfer member driving roller 5 is set slightly smaller than the designed value. Therefore, the peripheral speed of the photoconductor 1 is slightly higher than that of the intermediate transfer member 4. The frictional force F generated between the photoconductor 1 and the intermediate transfer body 4 due to this peripheral speed difference acts in the direction of arrow F in FIG. 1, that is, acts as a load on the photoconductor drive roller 2. Therefore, the photoconductor drive gear 2a and the intermediate transfer body drive gear 5a can always be stably transmitted from the intermediate transfer body drive gear 5a to the photoconductor drive gear 2a while meshing in a fixed direction.

[0022]

As described above, according to the present invention, the diameter of the photoconductor driving roller is set slightly larger than the design value, and the diameter of the intermediate transfer member driving roller is set slightly smaller than the design value. By configuring the peripheral speed of the photoconductor to be slightly higher than the peripheral speed of the intermediate transfer member, the frictional force generated between the photoconductor and the intermediate transfer member due to the difference in peripheral speed causes the photosensitive member drive roller to move. Since it acts as a load on the photoconductor drive gear and the intermediate transfer body drive gear, the drive force can be stably transmitted from the intermediate transfer body drive gear to the photoconductor drive gear while always meshing in a fixed direction. It is possible to prevent the occurrence of speed fluctuations due to the change of contact points during the backlash, and to realize an electrophotographic apparatus in which color misregistration and color unevenness are less likely to occur.

[Brief description of drawings]

FIG. 1 is a side view of a photosensitive member / intermediate transfer member driving device of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 3 is a side view of a photoconductor / intermediate transfer member driving device of a conventional color electrophotographic apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Photoconductor drive roller 2a Photoconductor drive gear 4 Intermediate transfer body 5 Intermediate transfer body drive roller 5a Intermediate transfer body drive gear 7 Drive motor 8 Intermediate transfer roller

Claims (3)

[Claims] 1. An electrophotographic apparatus having a step of transferring a toner image formed on an endless belt-shaped photoconductor to an endless belt-shaped intermediate transfer member, wherein the device for driving the intermediate transfer member is the intermediate transfer member. The intermediate transfer member driving roller that stretches the intermediate transfer member to drive the intermediate transfer member, and the intermediate transfer member driving gear that is fixed on the shaft of the intermediate transfer member driving roller and meshes with the driving source gear, drive the photosensitive member. The device includes a photoconductor drive roller that stretches the photoconductor and drives the photoconductor, and a photoconductor drive gear that is fixed on the shaft of the photoconductor drive roller and meshes with the intermediate transfer body drive gear. Then, the toner image on the photosensitive member is transferred to the intermediate transfer member by pressing the intermediate transfer member against the photosensitive member on the photosensitive member driving roller, and the peripheral speed of the photosensitive member is set to the peripheral speed of the intermediate transfer member. Less than speed Photoreceptor, intermediate transfer body driving device faster the electrophotographic apparatus. 2. When the diameter of the photosensitive member driving roller is Da, the diameter of the intermediate transfer member driving roller is Db, the number of teeth of the photosensitive member driving gear is Za, and the number of teeth of the intermediate transfer member driving gear is Zb, Da is: 2. The photosensitive member / intermediate transfer member driving device for an electrophotographic apparatus according to claim 1, wherein the peripheral speed of the photosensitive member is slightly higher than that of the intermediate transfer member by setting / Db> Za / Zb. 3. When the diameter of the photosensitive member driving roller is Da, the diameter of the intermediate transfer member driving roller is Db, the number of teeth of the photosensitive member driving gear is Za, and the number of teeth of the intermediate transfer member driving gear is Zb, Da is: By setting / Db> Za / Zb, the contact point between the intermediate transfer body drive gear and the photosensitive body drive gear is on the line of action from the intermediate transfer body drive gear to the photosensitive body drive gear, and the intermediate transfer body drive gear always moves. 2. The photosensitive member / intermediate transfer member driving device for an electrophotographic apparatus according to claim 1, wherein the tooth surface presses the tooth surface of the photosensitive member driving gear.