JP2957765B2 - 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 apparatus or an electrostatic recording apparatus.

[0002]

2. Description of the Related Art A multi-color copying machine having a plurality of photosensitive drums as image carriers, and does not use image forming units of all colors, but performs copying using some of the image forming units. Conventionally, all the photosensitive drums are rotated or the photosensitive drums of the image forming units other than those used are stopped.

[0003]

However, in the above-mentioned conventional example, when the image formation is performed only in, for example, the third image formation unit among the plurality of image formation units, the I and I image formation units are required.
The photosensitive drums of the I and IV image forming units are stopped.
In this case, the I, I, upstream of the III image forming unit
There is no problem in the image quality when the photosensitive drum of the image forming unit is stopped,
When the photosensitive drum of the IV image forming unit is stopped, the unfixed toner on the recording material comes into contact with the stopped photosensitive drum, and the image is disturbed.

When all the photosensitive drums rotate,
The life of the photosensitive drum is shortened.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to stop only unnecessary photosensitive drums, thereby improving the life of the unfixed toner image without disturbing the toner image. An object of the present invention is to provide an image forming apparatus.

[0006]

According to the present invention, there is provided an electrophotographic multicolor image forming apparatus having a plurality of image carriers, wherein An image carrier not involved in image formation upstream of the image carrier involved in image formation is stopped, and an image carrier not involved in image formation downstream of the image carrier involved in image formation is rotated. And a drive control device for performing control for causing the drive to be performed.

It is preferable that the drive control device performs control to start and stop the rotation of the photosensitive drum in accordance with the advance of the recording material.

Further, before the image forming is started, the drive controller rotates the image carrier at a low speed, and controls the image carrier to rotate and stop according to the progress of the recording material. It is desirable to make.

[0009]

[0010]

[0011]

[0012]

Embodiment ( Reference Example 1) FIG. 1 shows an example of an image forming apparatus common to an embodiment of the present invention and a reference example .

Each image forming unit I as image forming means
To IV have photosensitive drums 11 to 14 as image carriers,
Around that, primary chargers 21 to 24 and exposure means 31 to 3
4. Developing devices 41 to 44, transfer chargers 51 to 54, and cleaners 61 to 64 are arranged. Further, an endless belt-shaped conveying means 10 is arranged below the photosensitive drum so as to penetrate each image forming unit. .

On the back of the photosensitive drums 11 to 14 shown in FIG.
It is directly connected to 1-14. The drive control device 8 as control means is electrically connected to the drive devices 71 to 74.

Developing devices 41 to 41 in image forming units I to IV
Each of 44 is filled with magenta, cyan, yellow, and black toners, and the recording material P is transported from a paper feeding device (not shown). Through IV, and the image of each color is transferred to obtain a full-color image.

The purpose of a multicolor image forming apparatus is to copy a four-color full-color image originally. However, depending on the user's request or the type of a copy to be an original, magenta, cyan, and yellow are sometimes used. It is possible that an image is formed using only one color, two colors or three colors of black.

FIG. 2 shows the rotation state of the photosensitive drum of the image forming unit. In the reference example 1 , the photosensitive drum that starts to rotate in response to the copy start signal is the most upstream (in the direction in which the recording material P is conveyed) in the single-color, two-color, or three-color image forming unit used in the copy image forming process. , The photosensitive drums of the image forming units downstream of the image forming unit are rotated, and the photosensitive drums of the other image forming units are not rotated.

For example, when an image is formed only in yellow, the image is formed by rotating only the photosensitive drums of the yellow and black image forming units (FIG. III).
reference).

The photosensitive drum motor of the image forming unit, which is the most upstream in the image forming unit for forming an image, starts pre-rotation at the same time as the copy start signal, and synchronizes with the copy start signal to record the image data supplied from a paper feeding device (not shown). Before the material P reaches the image forming unit, the pre-rotation is completed, and the image formation is started. The downstream image forming unit also performs the same process. However, in the image forming unit that is not involved in image formation, the pre-rotation, the image forming step, and the post-rotation are not performed, and only the rotation of the photosensitive drum for passing the recording material P is performed. Do.

By controlling the photosensitive drum of each image forming unit as described above, the unfixed toner image on the recording material is prevented from being disturbed by the photosensitive drum on the downstream side.

At this time, since the unnecessary photosensitive drum is stopped, the life of the photosensitive drum is extended.

Hereinafter, another reference example of the present invention will be described. The same components as those of the first embodiment will be described with the same reference numerals. Reference Example 2 FIG. 3 shows a reference example obtained by further developing Reference Example 1. At the same time as the copy start signal, the endless belt-shaped conveying means 10 rotates, and the recording material P starts to be conveyed from a sheet cassette (not shown). The pre-rotation process is completed before the recording material P approaches the image forming unit that is the most upstream of the image forming units I, II, III, and IV where image formation is to be performed, and before the recording material P reaches the image forming unit. When possible, a photosensitive drum motor mounted to rotate the photosensitive drum in the most upstream image forming unit starts rotating, the photosensitive drum rotates, and enters a pre-rotation step. After the completion of the pre-rotation, the photosensitive drum immediately enters an image forming process, and transfers the toner image onto the recording material P. The image forming unit that has completed the image formation and has conveyed the recording material P to the one downstream image forming unit immediately enters a post-rotation step, and stops the rotation of the photosensitive drum at the end of the post-rotation. The downstream image forming unit repeats the same process as described above in synchronization with the recording material P conveyance timing. ( Example) An example of the present invention will be described below. Reference Example 1 and
The same components as in FIG. 2 are described with the same reference numerals.
In Reference Example 2, the photosensitive drum of each image forming unit was sequentially rotated as the recording material P progressed, and the photosensitive drum was stopped after image formation or as the recording material P passed.

In this embodiment shown in FIG. 4, the photosensitive drum is used for image formation before and after the previous rotation or after the recording material P is not passed.
It is rotated at a second speed lower than the first speed at the time of formation . In FIG. 4 , the state indicated by １ ／ indicates rotation at the second speed, but 、 is a numerical value used for convenience and has no relation to the actual speed.

This makes it possible to reduce the rising shock during rotation of the photosensitive drum and to improve the image quality, and to extend the life of the photosensitive drum and the endless belt.

Further, when the rotation is increased from the low rotation to the normal rotation, the shock caused by the motor torque can be further reduced by gradually increasing the rotation using, for example, a clutch without a clutch.

[0026]

According to the present invention as described above ,
When the second mode is selected, a predetermined image carrier
An image bearing member on the upstream side in the conveying direction of the recording material;
Stop the image carrier on the upstream side where no image is formed by the step
Therefore, the life of the image carrier on the upstream side is prevented from being shortened.
And the predetermined image carrier rotates at a first speed.
Before starting rotation, downstream of the predetermined image carrier in the transport direction
An image forming member, on which an image is not formed by the image forming means.
The image carrier on the downstream side is rotated at a second speed to
The recording material carried on the carrier faces the downstream image carrier
When passing through the position, the image carrier on the downstream side is moved at the first speed.
Rotate to prevent image distortion on the recording material.
In addition, the image quality due to the shock when the image carrier rotates
And the life of the downstream image carrier is shortened.
Can be satisfactorily prevented.

[0027]

[0028]

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a main part of an image forming apparatus according to an embodiment of the present invention and first and second reference examples .

It is an operation explanatory view of an image forming apparatus according to a first reference example of the present invention; FIG.

FIG. 3 is an operation explanatory view of an image forming apparatus according to a second reference example of the present invention.

4 is an explanatory diagram of the operation of the image forming apparatus according to the actual施例of the present invention.

[Explanation of symbols]

 8 drive control device 11, 12, 13, 14 photosensitive drum (image carrier)

Claims (4)

(57) [Claims] A plurality of rotatable image carriers; and a plurality of rotatable image carriers.
Images forming a plurality of color images on an image carrier
Forming means and control for controlling rotation of the plurality of image carriers
Means, and a recording material carrier for supporting the recording material,
The plurality of image carriers formed by the plurality of image forming means.
The multi-color image on the body was carried on the recording material carrier
In an image forming apparatus capable of sequentially forming on a recording material, the apparatus forms an image using the plurality of image carriers.
A first mode, and a predetermined image bearing among the plurality of image carriers.
A second mode in which image formation is performed using only the carrier.
The control means controls the rotation speed of the image carrier to the image carrier.
An image is formed on the recording material carried by the recording material carrier from the holding body.
A first speed to achieve and slower than the first speed
And a second speed.
Is selected, the recording material is higher than the predetermined image carrier.
An image carrier on the upstream side in the conveying direction of the image forming means,
The image carrier on the upstream side where no image is formed due to
And the predetermined image carrier rotates at the first speed.
Before starting, in the transport direction more than the predetermined image carrier
An image carrier on the downstream side, wherein an image is formed by the image forming unit.
The non-formed downstream image carrier is moved at the second speed.
The recording material carried by the recording material carrier is rotated
When passing through a position facing the image carrier on the downstream side,
An image forming apparatus , wherein a downstream image carrier is rotated at the first speed . 2. The printing apparatus according to claim 1 , wherein said control means is provided on said recording material carrier.
The held recording material passes through a position facing the image carrier.
Then, the image carrier is rotated at the second speed.
The image forming apparatus according to claim 1, wherein: 3. The image forming means according to claim 1 , wherein
Provide cleaning means for cleaning residue.
The image forming apparatus according to claim 1, wherein: 4. An image forming apparatus according to claim 1, wherein each of said image forming means is a belt.
4. A charging device comprising:
3. The image forming apparatus according to any one of 3.