JP2836559B2 - Electrophotographic color printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic color printer that performs exposure using a laser beam, and more particularly, to forming a color image by superimposing a plurality of color images formed on a photoreceptor belt on a transfer belt. And an electrophotographic color printer.

2. Description of the Related Art In an electrophotographic color printer, scanning is performed using a laser beam to form a latent image for each of the separated colors on a photoreceptor belt, and after development, an image of each color is superimposed on a transfer belt. Transfer to form a color image and then print.

At this time, it is necessary to prevent a color shift between the colors in the color image synthesized on the transfer belt.

[0004]

2. Description of the Related Art In an electrophotographic color printer using a laser beam, laser beam scanning means is used.
A latent image corresponding to each of the separated color images is formed on the photoreceptor. The latent image formed on the photoreceptor is developed as a color toner image one by one with a developing material of each color, and the developed toner images of each color are sequentially superimposed and transferred on the transfer material, thereby transferring the image. An image corresponding to a color image is formed on a material.

In such an electrophotographic color printer using a laser beam, a color image is formed by sequentially superimposing toner images of each color. It is important to prevent color shift.

Therefore, the position of the leading end of the transfer material on the transfer material support is detected, and a horizontal synchronization signal and a vertical synchronization signal are generated according to the position of the transfer material on the transfer material support. Based on this, the image data is formed on the photoreceptor and transferred onto a transfer material so that the distance from the exposure position on the photoreceptor to the transfer position in the rotational direction is made equal.

Further, in order to eliminate a phase shift between the detection signal of the leading end position of the transfer material and the horizontal synchronization signal, a drive motor for rotating the photosensitive member and the transfer material support and a laser beam on the photosensitive member are scanned. The control of synchronizing the driving of the scanning means is performed. A color printer having such a structure is disclosed in JP-A-4-195071.

When a multicolor image is formed by superposing an image of each color formed by developing an electrostatic latent image on a photoreceptor by performing exposure scanning for each color and developing the same, a rotation of the photoreceptor is performed. The PLL is controlled so as to have a constant relationship between the speed, the rotation speed of the polygon mirror, and the number of mirror surfaces of the polygon mirror.
Japanese Patent Laid-Open No. 5-61309 discloses that by controlling the color shift of the superimposed images is prevented.

[0009]

As described above, in an electrophotographic color printer using a laser beam,
By synchronizing the drive of the drive motor for rotating the photoconductor and the transfer material support with the drive of the scanning means for scanning the laser beam on the photoconductor, color shift of a color image is prevented.

However, since there is a limit in the manufacturing accuracy of the drive transmission mechanism between the photoconductor and the transfer material support and the drive motor, the rotation of the photoconductor and the transfer material and the scanning of the laser beam on the photoconductor are limited. It is difficult to synchronize with high accuracy. Furthermore, when a photoreceptor belt is used as the photoreceptor or a transfer belt is used as the transfer material, slippage occurs between the respective supports, so that the rotation of the photoreceptor and the transfer material and the laser beam on the photoreceptor It is even more difficult to accurately synchronize the scan with the scan.

Therefore, in the conventional electrophotographic color printer using a laser beam, there is a problem that it is inevitable that a color shift occurs when an image formed on a photosensitive member is transferred to a transfer material. Was.

An object of the present invention is to solve such a problem of the prior art. In an electrophotographic color printer using a laser beam, a photosensitive belt and a transfer belt are used.
By removing the effects of slippage with the printer, the rotation of the transfer photoconductor and the transfer material can be synchronized with the scanning of the laser beam on the photoconductor with high accuracy, and high-quality color without color shift An object of the present invention is to provide an electrophotographic color printer capable of obtaining an image.

[0013]

In order to solve the above-mentioned problems, the present invention has the following specific means.

As a first means, a laser beam for each color is used.
Scanning means for scanning the photosensitive member on the photosensitive belt, and a predetermined reference signal.
Scanning system that controls the scanning speed of the laser beam based on the signal
Control and horizontal synchronization by detecting the scanning position of the laser beam
A horizontal synchronization detection circuit for generating a signal and scanning means
Image corresponding to laser beam scanned on photoreceptor belt
A plurality of developing units for each color, and the plurality of developing units
The images formed on the photoreceptor belt by
Next transfer and color image formed by the transfer
A transfer belt for printing an image on a recording medium.

In addition, the photosensitive belt and the transfer belt
In the rotation direction of the photosensitive belt or the transfer belt,
Patterns are formed at regular intervals. In addition, photoreceptor bell
Based on the pattern in accordance with the drive of the photosensitive belt.
Pulse generating means for a photoreceptor for generating a pulse signal
Horizontal sync signal output from horizontal sync detection circuit and photoconductor
Based on the pulse signal output from the
Photoreceptor belt driving means for driving the photoreceptor belt
Has been adopted.

As the second means, the first means is specified.
Addition to those, the transfer belt, response to the driving of the transcription belt
Transfer bell that generates a pulse signal based on the pattern
Output from the horizontal pulse detection circuit
Output from the horizontal sync signal and the photoreceptor pulse generator.
Transfer belt that drives the transfer belt based on the
The configuration is such that a tilt driving means is provided.

As the third means, the first or second means is specially described.
In addition to the items specified, the pattern on the transfer belt
It is formed at intervals of an integral multiple of the pixel interval formed on the photo belt.
Is adopted.

In this manner, when performing multiple transfer for each color, the rotation of the photosensitive belt and the transfer belt can be synchronized, so that image formation and transfer processing without color shift can be performed. Becomes possible.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG . 1 is a block diagram showing the configuration of an electrophotographic printer according to the present invention, and FIG. 2 is a perspective view of a mechanism. The electrophotographic printer includes a scanning unit 4 for scanning a laser beam of each color on the photoreceptor belt 8 and a scanning control unit for controlling a scanning speed of the laser beam based on a reference signal output from a reference signal generating circuit 1. (Laser drive circuit) 2, a plurality of developing units 24 to 27 for developing a latent image formed in accordance with the laser beam scanned on the photosensitive belt by the scanning unit 4, and a plurality of developing units 24 to 27
An image formed on the photoreceptor belt 8 is sequentially transferred for each color by 27 and a transfer belt 16 for printing a color image on a recording medium is provided.

In addition, a pulse generator (photosensitive belt position sensor) 15 for generating a pulse signal on the photosensitive belt 8 in accordance with the driving of the photosensitive belt 8
A horizontal synchronization detecting circuit 10 for detecting a scanning position of the laser beam to generate a horizontal synchronization signal; a horizontal synchronization signal output from the horizontal synchronization detection circuit 10 and a pulse output from the photoconductor pulse generating means 15 Photoreceptor belt driving means 12 and 18 for driving the photoreceptor belt based on a signal are provided.

The reference signal generating circuit 1 has a reference oscillator and generates a stable reference clock. The scanning means includes a polygon mirror 4 for reflecting a laser beam to the photoreceptor belt, a scanner motor 3 for rotating the polygon mirror, and a scanner motor drive circuit 2 for driving the scanner motor 3
And

The scanner motor drive circuit 2 includes a PLL
A driving signal for driving the scanner motor 3 in synchronization with a reference clock from the reference signal generating circuit 1. The scanner motor 3 rotates the polygon mirror 4 attached to the rotating shaft at a constant speed according to the drive signal. The polygon mirror 4 has a plurality of mirrors, and reflects and deflects the light beam from the laser 5 in the horizontal direction. lens 6 condenses the laser beam from polygon mirror 4 and reflects it on reflection mirror 7 to form a scanning spot on photosensitive belt 8.

The photoreceptor belt 8 is an endless belt having photosensitivity, and is driven by a photoreceptor belt drive motor 20 to rotate.

The laser beam scanning detection sensor 9 detects a reflected light beam from the reflection mirror 7 at the end of the photosensitive belt 8 and generates a detection signal. The horizontal synchronization detection circuit 10 generates a horizontal synchronization signal pulse based on the detection signal of the laser beam scanning detection sensor 9. Counting circuit 1
1 counts horizontal synchronization signal pulses. The photoconductor belt drive motor control circuit 12 controls the photoconductor belt drive motor drive circuit 18 based on the count result of the counting circuit 11 and the rotation position of the photoconductor belt 8. The transfer belt drive motor control circuit 13 controls the transfer belt drive motor drive circuit 19 based on the count result of the counting circuit 11 and the rotational position of the transfer belt 16.

The image data control circuit 14 includes a counting circuit 11
The output timing of the image data generation circuit 22 is controlled based on the count result of the above. The photoreceptor belt position sensor 15 supplies a signal indicating the rotation position of the photoreceptor belt 8 to the photoreceptor belt drive motor control circuit 12. As a result, the photoconductor belt position sensor 15 operates as a photoconductor pulse generating unit.

The transfer belt 16 is an endless belt capable of transferring a toner image, and is driven by a transfer belt drive motor 21 to rotate.

The transfer belt position sensor 17 gives a signal indicating the rotational position of the transfer belt 16 to the transfer belt drive motor control circuit 13. Thereby, the transfer belt position sensor 17 operates as a transfer pulse generating unit. The photosensitive belt drive motor drive circuit 18 drives the photosensitive belt drive motor 20 to rotate the photosensitive belt 8. The transfer belt drive motor drive circuit 19 drives the transfer belt drive motor 21 to rotate the transfer belt 16.

The image data generating circuit 22 outputs image data under the control of the image data control circuit 14.
The laser drive circuit 23 drives the laser 5 to emit light according to the image data output of the image data generation circuit 22. The developing device 24 develops the first color latent image on the photoreceptor belt 8. The developing device 25 develops the second color latent image on the photoreceptor belt 8. The developing device 26 develops the third color latent image on the photoreceptor belt 8. The developing device 24 includes the photosensitive belt 8
The upper fourth latent image is developed.

[0030] Hereinafter, will be explained with reference to FIGS. 3 and 4 the operation of the electrophotographic color printer shown in FIGS. First, the scanner motor 3 is driven by PLL control of the scanner motor drive circuit 2 based on a predetermined reference clock generated by the reference signal generation circuit 1, so that the polygon mirror 4 attached to the scanner motor 3 rotates. Thus, the laser beam from the laser 5 is scanned on the photosensitive belt 8 via the fθ lens 6 and the reflection mirror 7.

The output of the laser beam scanning detection sensor 9 attached to the scanning start position of the laser beam is waveform-shaped in the horizontal synchronizing detection circuit 10 is output to the counting circuit 11 as a horizontal synchronizing signal pulse. In the counting circuit 11, according to the result of counting a predetermined number of horizontal synchronization signal pulses,
A photoreceptor belt drive motor clock is generated, output to the photoreceptor belt drive motor control circuit 12, a transfer belt drive motor clock is generated, output to the transfer belt drive motor control circuit 13, and a vertical synchronization signal is generated. And outputs it to the image data control circuit 14.

The photosensitive belt 8 is driven by a photosensitive belt drive motor 20. 3 are formed on the photoreceptor belt 8 at regular intervals. The photoreceptor belt position sensor 15 detects this pattern and outputs a pattern detection signal to the photoreceptor belt drive motor control circuit. 12 is output. The interval between the patterns on the photoreceptor belt 8 is an integral multiple of the pixel interval, and the length of the photoreceptor belt 8 is also determined by this restriction.

The transfer belt 16 is driven by a transfer belt drive motor 21. On the transfer belt 16, patterns at equal intervals are formed similarly to the photoreceptor belt 8, and the transfer belt position sensor 17 detects this pattern and sends a pattern detection signal to the transfer belt drive motor control circuit 13. Output. The interval between the patterns on the transfer belt 16 is an integral multiple of the pixel interval, and the length of the transfer belt 16 is also determined by this limitation.

The photoreceptor belt drive motor control circuit 12 controls the photoreceptor belt drive motor clock from the counting circuit 11 and the pattern detection signal from the photoreceptor belt position sensor 15 so that the frequency difference and the phase difference become zero. The photoreceptor belt drive motor 20 is PLL-controlled via the photoreceptor belt drive motor drive circuit 18.

In the transfer belt drive motor control circuit 13,
A transfer belt driving motor clock from the counting circuit 11;
The transfer belt drive motor 21 is PLL-controlled via the transfer belt drive motor drive circuit 19 so that the frequency difference and the phase difference of the pattern detection signal from the transfer belt position sensor 17 become zero.

The counting circuit 11 operates as shown in FIG. 4 based on the horizontal synchronizing signal pulse (a) from the horizontal synchronizing detection circuit 10 to drive the photosensitive belt driving motor clock (b) and the transfer belt driving. Outputs motor clocks (c) and (d) and vertical synchronization signal (e). The vertical synchronization signal is generated so as to correspond to a specific position on the transfer belt 16.

The image data control circuit 14 includes the counting circuit 11
The timing of output of image data for each color is controlled based on the vertical synchronizing signal from. Image data generation circuit 22
Outputs image data based on a start signal from the image data control circuit 14. Laser drive circuit 23
Drives the laser 5 to emit light based on the image data signal from the image data generation circuit 22.

The laser beam from the laser 5, the polygon mirror 4, the scanning means comprising a fθ lens 6 and the reflection mirror 7 to form a latent image corresponding to the image data on the photoreceptor belt 8. The latent image on the photoreceptor belt 8 is developed for each color by the developing units 24 to 27 and sequentially transferred onto the transfer belt 16 in a superimposed manner. The color printing is performed by being transferred onto the upper surface again.

[0039]

As described above, in the electrophotographic color printer using the laser beam according to the present invention, the sensitivity is high.
A pattern is provided on each of the optical belt and the transfer belt,
The rotation of the photoreceptor belt and the transfer belt
Synchronized using the above pattern, so each color
Image without color shift even when performing multiple transfer
Formation and transfer processes can be performed,
It is possible to print high quality color images without color shift.
Electrophotographic Karapu printer with excellent unprecedented that kill
Can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electrophotographic color printer using a laser beam according to the present invention.

FIG. 2 is a perspective view showing a configuration of a mechanism of the electrophotographic color printer shown in FIG.

FIG. 3 is an explanatory view showing a pattern on the photoreceptor belt shown in FIG. 1, and FIG. 3 (A) is a view showing the pattern;
(B) is a diagram showing a photoreceptor belt provided with a pattern.

FIGS. 4A and 4B are time charts showing various signals in the electrophotographic color printer of the present invention, wherein FIG. 4A shows a horizontal synchronizing signal, FIG. 4B shows a photoreceptor belt driving motor clock, and FIG. (D) shows a transfer belt drive motor clock, and
(E) shows a vertical synchronization signal, and (f) is a partially enlarged view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference signal generation circuit 2 Scanner motor drive circuit 3 Scanner motor 4 Polygon mirror 5 Laser 6 fθ lens 7 Reflection mirror 8 Photoconductor belt 9 Laser beam scanning detection sensor 10 Horizontal synchronization detection circuit 11 Counting circuit 12 Photoconductor belt drive motor control circuit Reference Signs List 13 transfer belt drive motor control circuit 14 image data control circuit 15 photosensitive belt position sensor 16 transfer belt 17 transfer belt position sensor 18 photosensitive belt drive motor drive circuit 19 transfer belt drive motor drive circuit 20 photosensitive belt drive motor 21 transfer belt Drive motor 22 Image data generation circuit 23 Laser drive circuit 24 to 27 Developing device 28 Recording paper

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/44 B41J 2/525

Claims (3)

(57) [Claims] A scanning means for scanning a laser beam for each color on a photosensitive belt; a scanning control means for controlling a scanning speed of the laser beam based on a predetermined reference signal; and a scanning position for the laser beam. A horizontal synchronization detection circuit for detecting and generating a horizontal synchronization signal; a plurality of developing units for each color for developing an image corresponding to a laser beam scanned on the photosensitive belt by the scanning unit; and a plurality of developing units. in electrophotographic color printer having a transfer belt for printing on a recording medium a color image formed by the transfer together with the photoreceptor belt image formed on are sequentially transferred the for each color by the photoreceptor To the belt and the transfer belt, respectively.
Pattern at regular intervals in the rotation direction of the optical belt or transfer belt
Forming a pattern on the photosensitive belt in accordance with the drive of the photosensitive belt.
For photoconductors that generate pulse signals based on the pattern
Pulse generating means, and output from the horizontal synchronization detection circuit.
Output from the photoconductor pulse generating means
Drives the photoreceptor belt based on the applied pulse signal
The transfer belt,
In accordance with the driving of the transfer belt,
Means for generating a pulse signal for a transfer belt
And a horizontal synchronization signal output from the horizontal synchronization detection circuit.
And the pulse signal output from the photosensitive member pulse generating means.
Transfer belt drive that drives the transfer belt based on the
An electrophotographic color printer characterized by comprising moving means . 2. The method according to claim 1 , wherein the pattern on the photoreceptor belt is
It is formed at an interval that is an integral multiple of the pixel interval formed on the photoreceptor belt.
2. An electrophotographic color printer according to claim 1, wherein:
-Printer. 3. The transfer belt according to claim 1 , wherein
It is formed at intervals of an integral multiple of the pixel interval formed on the photo belt.
The electrophotographic camera according to claim 1 or 2,
Printer .