JP3088289B2 - 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, and more particularly, to developing a latent image formed on a photoreceptor with a developer and transferring and fixing the latent image on recording paper, or
The present invention relates to an image forming apparatus that transfers a visible image to an intermediate transfer medium, and then transfers and fixes the image from the intermediate transfer medium to recording paper.

[0002]

2. Description of the Related Art Conventionally, this type of image forming apparatus firstly
A latent image is formed on a photoreceptor, and an image obtained by visualizing the latent image with a developer is directly transferred to a recording sheet, or in an electrophotographic recording process of transferring the image to a recording sheet via an intermediate transfer medium,
If the images formed on the photoreceptor are not uniformly spaced, density unevenness on the horizontal stripe called banding occurs. Factors that disturb the image formed on the photoreceptor include vibrations related to the rotation and movement mechanisms of the photoreceptor, and variations in manufacturing parts. In addition, when the intermediate transfer medium is used, there are vibrations related to the mechanism of rotation and movement of the intermediate transfer medium, and variations in manufacturing parts.

[0003] In order to minimize these effects, measures are generally taken to increase the precision of the parts and to prevent vibration resonance. Japanese Patent Application Laid-Open No. Hei 5-165271 discloses FIG.
Have been proposed. Photoreceptor rotation axis 11
A toothed pulley 121 is attached to 3a. Further, a drive motor 122 is provided in the apparatus main body 110, and a toothed pulley 123 is attached to a rotation shaft 122a. A belt 124 provided with teeth that mesh with those teeth is stretched between the toothed pulleys 121 and 123. Then, a tension pulley 125 is provided between the toothed pulleys 121 and 123 and pressed against the back of the belt 124. Toothed pulley 12
The teeth of Nos. 1 and 123 have a Young's modulus of 50-5000 kg /
It is formed of an elastic member of cm ² . And the drive motor 12
2 is operated, the toothed pulley 123 rotates and the belt 124 runs. Then, the toothed pulley 121 rotates to rotate the photoconductor, and the tooth portion is elastically deformed at the time of meshing, thereby eliminating backlash. it can.

[0004]

The above-described conventional image forming apparatus has an effect of reducing the density unevenness on the photosensitive member, but is insufficient. In particular, during multiple recording for obtaining a color image, the influence of banding due to density unevenness greatly affects the image, and the conventional method has a problem that the effect of reducing density unevenness is small.

An object of the present invention is to provide an image forming apparatus capable of obtaining a stable image even when there is a mechanical factor such as vibration or defective component accuracy.

[0006]

According to the present invention, there is provided an image forming apparatus comprising: means for forming a reference visual image based on reference image information on a photosensitive member at a time other than the actual printing time; and means for reading the reference visual image. Means for comparing the read reference visual image with reference image information, and transferring the reference visual image to an intermediate transfer medium
Means for reading the read reference transfer image,
Means for comparing the quasi-transfer visual image with reference image information and means for controlling the rotational speed of the photoconductor or the intermediate transfer medium based on the compared information are provided.

[0007]

[0008]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a color laser printer according to an embodiment of the present invention.

The color laser printer includes a laser scan unit 2 for forming a latent image on a photoreceptor 1 and a developing device for developing a latent image on the photoreceptor 1 to form a visible toner image.
A yellow developing device 3, a magenta developing device 4, a cyan developing device 5, a black developing device 6, and an intermediate transfer medium 7 installed for superimposing the toner visible image of the photoconductor 1 by one color; A transfer device 8 for transferring the toner image on the intermediate transfer medium 7 to the recording paper, a fixing device 9 for melting the toner on the recording paper to fix the image on the recording paper, and a device for rotating the photoconductor 1 Photoconductor motor 10, transfer medium motor 11 for rotating intermediate transfer medium 7, photoconductor detector 12 for detecting a visible toner image on photoconductor 1, intermediate transfer medium for detecting image information on intermediate transfer medium 7 It is formed from a detector 13. The controller 14 controls the entire color laser printer.

Next, the operation of FIG. 1 will be described with reference to FIGS.

FIG. 2 is a block diagram of the control system.

FIG. 3 is a diagram showing an example of a reference signal pattern.

FIG. 4 is a diagram showing an example of a detection signal.

The controller 14 includes an engine controller 21, a reference signal generator 22, a laser scan unit drive unit 23, an A / D converter 24, and a photoconductor motor control unit 25.
And a transfer medium motor control unit 26.

The engine controller 21 reads the information of the reference signal generated by the reference signal generator 22 at the time of non-printing, and reads the information at the time of the laser scanning unit driving section 2.
Send to 3. The laser scan unit driving section 23 emits the laser of the laser scan unit 2. In accordance with the laser light emitted along the reference signal, a latent image having a reference pattern is formed on the photoconductor 1. At this time, the photoconductor motor control unit 25 controls the photoconductor motor 10 as a single unit at a constant speed. As for the developing devices arranged to form a visible toner image with respect to the latent image formed on the photoconductor 1, four developing devices of yellow, magenta, cyan and black are arranged for color multiplex recording. Only one developing device selected by the controller 21 selectively opposes the photoconductor 1 to form a visible toner image on the photoconductor 1. Further, an image is transferred from the photoconductor 1 to the intermediate transfer medium 7.

In the non-printing state, as shown in FIG.
When a pattern serving as a reference, for example, a pattern forming an M line width for every N lines is generated, the photoconductor detector 12 and the intermediate transfer medium detector 13 should originally be able to obtain image information of a fixed period. If there is a mechanical factor such as vibration, component accuracy failure, etc., for example, a detection signal as shown in FIG. 4 is obtained. The signal indicated by the broken line in FIG. 4 is a signal that should be originally obtained. The detection signal is converted into a rectangular wave by the AD converter 24, and the signal is compared with a reference signal by the engine controller 21. Then, the engine controller 21 issues a command to the photoconductor motor control unit 25 and the transfer medium motor control unit 26 so that the cycle of the detection signal becomes uniform.

In these control loops, when a uniform detection signal cannot be obtained even when the engine controller 21 controls the motor, it is possible that a mechanical failure may have occurred. It is also possible to stop and indicate a device failure.

In this embodiment, a color laser printer using an intermediate transfer medium is taken as an example. However, when an intermediate transfer medium is not used, the motor, detector, and control unit relating to this can be omitted.

[0020]

As described above, according to the present invention, since image unevenness caused by poor precision of components or mechanical vibration is detected and feedback-controlled, a good image without banding can be obtained. There is.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram of a control system.

FIG. 3 is a diagram illustrating an example of a reference signal pattern.

FIG. 4 is a diagram illustrating an example of a detection signal.

FIG. 5 is a configuration diagram showing a conventional technique.

[Description of Signs] 1 Photoconductor 2 Laser Scan Unit 3 Yellow Developing Unit 4 Magenta Developing Unit 5 Cyan Developing Unit 6 Black Developing Unit 7 Intermediate Transfer Medium 8 Transfer Unit 9 Fixing Unit 10 Photoconductor Motor 11 Transfer Medium Motor REFERENCE SIGNS LIST 12 photoconductor detector 13 intermediate transfer medium detector 14 controller 21 engine controller 22 reference signal generator 23 laser scan unit drive unit 24 AD converter 25 photoconductor motor control unit 26 transfer medium motor control unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 15/00 G03G 15/16 G03G 21/00 G03G 21/14

Claims (1)

(57) [Claims] An image forming apparatus for developing a latent image formed on a photoreceptor with a developer, transferring the developed image to an intermediate transfer medium, and transferring and fixing the intermediate image to a recording sheet from the intermediate transfer medium. A means for forming a reference visual image based on reference image information on the photoconductor at a time other than the actual printing time; a means for reading the reference visual image; and comparing the read reference visual image with reference image information. Means for reading, a means for reading a reference transfer visual image obtained by transferring the reference visual image to the intermediate transfer medium,
An image forming apparatus comprising: means for comparing the read reference transfer visual image with reference image information; and means for controlling a rotation speed of the photoconductor or the intermediate transfer medium based on the compared information.