JPH05188724A - Device for forming color image and method thereof - Google Patents

Abstract

PURPOSE:To provide a color image forming device and color image forming method by which image quality can be set and image forming can be made efficient. CONSTITUTION:A control part 18 outputs a speed control signal corresponding to a mode selected signal to a motor drive unit 20 and controls the rotating speed of a photosensitive drum 1 so as to be variable. Then, the control part 18 outputs a scanning speed control signal corresponding to the speed control signal to a drive unit 21 and controls so that the scanning speed of the laser beam L of an optical writing unit 3 synchronizes with the rotating speed of the photosensitive drum 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a color printer, a digital color copying machine or a color facsimile which forms a color toner image on a photosensitive member and transfers it onto a recording sheet by using an electrophotographic process. Regarding

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing an example of a conventional color copying machine, and a process of forming a color toner image on a photoconductor and a transfer process to a recording paper will be described with reference to FIG.

While the photosensitive drum 1 rotates in the direction of arrow A, the charging charger 2 uniformly charges the photosensitive member 1a of the photosensitive drum 1. After that, the optical writing unit 3
Scans the photosensitive member 1a with a laser beam corresponding to the black (Bk) image information obtained by decomposing the original image information and exposes it to form an electrostatic latent image. The Bk developing device 4a has Bk toner stocked therein, and develops the electrostatic latent image on the photoconductor 1a with the Bk toner to form a Bk toner image. At this time, the developing devices 4b, 4c other than the Bk developing device 4a,
The operation of the cleaning device 4d is stopped so that the toner of each color inside does not adhere to the photoconductor 1a.
Is separated from the photoconductor 1a and does not contact the formed toner image. The charge removing charger 6 neutralizes the charge of the photoconductor 1a on the surface of which the toner image is formed. The above process is performed while the photosensitive drum 1 makes one rotation.

The same process as described above is repeated based on the image information of yellow (Y), magenta (M), and cyan (C), and the toner images of the respective colors are superposed, whereby the photosensitive member 1 is obtained.
A color toner image is completed on a.

When the image formation is started, the recording paper 7 is started to be conveyed by the paper feed roller 8 and the color toner image is formed on the photoreceptor 1a.
When completed, it is sandwiched by the pair of registration rollers 9 and is on standby. The registration roller pair 9 feeds the recording paper 7 to the conveyance path 10 in synchronization with the position of the leading edge of the color image on the photoconductor 1a. The color toner image on the photoconductor 1a is electrostatically transferred onto the recording paper 7 by the transfer charger 11, and the recording paper 7 on which the color toner image is transferred is neutralized by the separation charger 12 and is exposed by the separation claw 13. It is peeled from the body 1 a and conveyed to the fixing unit 14. The fixing unit 14 heats and fixes the color toner image on the recording paper 7, and the recording paper 7 is discharged to the paper discharge unit 15. At the time of transfer, the rotation speed of the photosensitive drum 1 is set to the recording paper 7 of the conveyance path 10 in order to form a normal image.
Must correspond to the transport speed for. On the other hand, the toner remaining on the photoconductor 1a after the electrostatic transfer is removed and collected by the cleaning unit 5 in pressure contact with the photoconductor 1a.

[0006]

In the above color copying machine, in order to form a color toner image on the photoconductor 1a, the processes of charging, exposing, developing and discharging are repeated,
Toner images of four colors of black, yellow, magenta, and cyan must be superposed, and the photosensitive drum 1 needs to rotate four times. Generally, the rotation speed of the photosensitive drum 1 is fixed to a speed corresponding to the conveyance speed of the conveyance path 10 with respect to the recording paper 7 (the linear speed becomes equal). Since the rotation speed of the photosensitive drum 1 is constant, the alignment accuracy of exposure for superimposing the toner images of the respective colors is also constant, and the image quality and the image forming time are determined. Therefore, the operator cannot arbitrarily select the image quality, and the waiting time until the copying is completed is constant even when performing the copying in which the image quality is not required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color image forming apparatus and a color image forming method capable of setting image quality and improving the efficiency of image formation in order to solve the above problems.

[0008]

In order to achieve the above-mentioned object, a color image forming apparatus of the present invention comprises a photoconductor on which a toner image is superposed and a color toner image is formed, and a drive for driving the photoconductor. In a color image forming apparatus including a motor and an optical writing unit that scans and exposes a photoconductor, a control unit receives an image quality setting signal from the outside, changes the drive speed of the drive motor, and performs the optical writing. It is characterized in that the scanning speed of the unit is changed in synchronization with the driving speed. Further, the control unit is configured to control the drive speed of the drive motor to a standard speed unless an image quality setting signal from the outside is input.

In the color image forming method of the present invention, the photosensitive member is driven at a low speed when an image of high image quality is formed, and the photosensitive member is driven at a high speed when an image is formed in a short time. However, the scanning speed of the optical writing unit is synchronized with the driving speed of the photoconductor.

[0010]

According to the color image forming apparatus of the above means, the control section receives the image quality setting signal from the outside, changes the drive speed of the drive motor, and synchronizes the scanning speed of the optical writing unit with the drive speed. The image quality and the image forming speed of the color image on the photoconductor can be variably controlled by changing the image quality. Furthermore, the control unit controls the drive speed of the drive motor to the standard speed unless an image quality setting signal from the outside is input, and when the signal from the outside is not input, the standard image quality is set to the standard time. Can be formed with.

According to the color image forming method of the above means, the photosensitive member is driven at a low speed when an image of high image quality is formed, and the photosensitive member is moved to a high speed when an image is formed in a short time. By driving at a high speed and synchronizing the scanning speed of the optical writing unit with the driving speed of the photoconductor, it becomes possible to form an image of high image quality or to form an image in a short time.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a color copying machine as an embodiment of the color image forming apparatus of the present invention in which the color image forming method of the present invention is carried out.

In FIG. 1, members corresponding to those described with reference to FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

A drive motor 16 is arranged inside the photosensitive drum 1, and a drive force is transmitted by a foam gear 17a and a worm wheel 17b to rotate in the direction of arrow A. In the optical writing unit 3, a polygon motor (not shown) rotates a polygon mirror so that the laser beam L is applied to the photoconductor 1.
It is configured to scan a.

A mode select signal is input to the controller 18 from the operation panel 19, and the controller 18 outputs a speed control signal corresponding to the mode select signal to the motor drive unit 20. The motor drive unit 20 outputs a speed signal to the drive motor 16 in order to control the rotation speed of the drive motor 16 in response to the speed control signal. Further, the control unit 18 outputs a scanning speed control signal corresponding to the rotation speed of the photosensitive drum to the drive unit 21, and the drive unit 21
A scanning speed signal corresponding to the scanning speed control signal is output to the optical writing unit 3, the rotation speed of the polygon motor and the emission timing of the semiconductor laser are controlled, and the scanning speed is synchronized with the rotation speed of the photosensitive drum 1.

When the operator needs to make a high-quality color copy for copying a color photograph or the like, when he presses the high-quality button 19a on the operation panel 19, the operation panel 19 sends a mode select signal corresponding to the high-quality mode button. Output to the control unit 18. The control unit 18 outputs a speed control signal for rotating the photosensitive drum 1 at a low speed in order to form a high quality image. Further, the control unit 18 outputs a scanning speed control signal for synchronizing the scanning speed with the rotation speed of the photosensitive drum 1.

The control unit 18 controls the rotation speed of the photosensitive drum 1 at a low speed and synchronizes the scanning speed for exposing the photosensitive member 1a with the rotation speed of the photosensitive drum 1.
The exposure alignment accuracy for superimposing the toner images of the respective colors is improved, and a high quality color copy can be obtained.

When the operator needs to make a color copy that does not require high image quality such as a simple color pattern in a short time, by pressing the high speed mode button 19b of the operation panel 19, when the high image quality mode button 19a is pressed. On the contrary, the control unit 18 controls the rotation speed of the photoconductor drum 1 at a high speed, and synchronizes the scanning speed for exposing the photoconductor 1a with the rotation speed of the photoconductor drum 1. As a result, the toner image of each color can be formed in a short time, and as a result, color copying can be obtained in a short time.

The control unit 18 does not input the mode select signal for a certain period of time after copying in the high image quality mode or the high speed mode, or when the standard mode button 19c is pressed, or when the power of the color copying machine is turned on. In the initial state, the standard mode is set, and the photosensitive drum 1 is controlled to rotate at the standard speed. This allows color reproduction of standard image quality to be obtained in standard time.

[0021]

As described above, according to the present invention,
The control unit receives the image quality setting signal from the outside, changes the drive speed of the drive motor, and changes the scanning speed of the optical writing unit in synchronization with the drive speed, thereby making it possible to set the image quality and further shorten the time. Since it is possible to form an image with, it is possible to provide a color image forming apparatus capable of improving the efficiency of image formation.

Further, the control unit can provide a color image forming apparatus which does not cause a malfunction by controlling the drive speed of the drive motor to the standard speed unless an image quality setting signal from the outside is input.

In the above color image forming apparatus,
When forming an image of high image quality, drive the photoconductor at a low speed, and when forming an image in a short time, drive the photoconductor at a high speed and synchronize the scanning speed of the optical writing unit with the drive speed. By doing so, the image quality can be set and the image can be formed in a shorter time, so that a color image forming method that can improve the efficiency of image formation can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color copying machine of an embodiment of a color image forming apparatus of the present invention in which a color image forming method of the present invention is carried out.

FIG. 2 is a configuration diagram showing an example of a conventional color copying machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoconductor drum, 1a ... Photoconductor, 3 ... Optical writing unit, 16 ... Drive motor, 18 ... Control part, 19 ... Operation panel, 20 ... Motor drive unit, 21 ... Drive unit.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/04 116 9122-2H

Claims (3)

[Claims] 1. A color image forming apparatus comprising: a photoconductor on which a toner image is superposedly formed to form a color toner image; a drive motor for driving the photoconductor; and an optical writing unit for scanning and exposing the photoconductor. The control unit is configured to receive an image quality setting signal from the outside and change the drive speed of the drive motor and change the scanning speed of the optical writing unit in synchronization with the drive speed. Color image forming apparatus. 2. The control unit is configured to control the drive speed of the drive motor to a standard speed unless an image quality setting signal from the outside is input.
Color image forming apparatus. 3. When forming an image of high image quality,
2. When the photoconductor is driven at a low speed to form an image in a short time, the photoconductor is driven at a high speed, and the scanning speed of the optical writing unit is synchronized with the drive speed of the photoconductor. Alternatively, a color image forming method using the color image forming apparatus according to claim 2.