JPS6165275A - Control method of electrophotographic printer - Google Patents

Abstract

PURPOSE:To make the pitch of lines of image information written on a photosensitive body constant regardless of the conveyance speed of the photosensitive body and to eliminate the distortion of an image by detecting the conveyance speed and writing the image information on the photosensitive body in synchronism with the conveying operation of the photosensitive body. CONSTITUTION:A synchronizing signal generating means consists of a photosensitive body drive state detector 3 and a PLL4. An image signal generator 8 uses a signal SB as a vertical synchronizing or clock signal to send an image signal which is generated by a computer 9, etc., and held in the video RAM of an image processing unit 10 to an optical writing element 11. Therefore, the optical writing element 11 writes a light image on the photosensitive body 1 in synchronism with the conveyance speed of the photosensitive body 1. Even if the conveyance speed of the photosensitive body varies, the signal SB varies in frequency accordingly, so the pitch of scanning lines is unchanged and neither the distortion nor density irregularity of an image is caused. Consequently, a small-sized, light weight, and inexpensive conveying means for the photosensitive body is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling an electrophotographic printer, and more particularly to a method for controlling an electrophotographic printer having an optical writing element composed of a plurality of light emitting elements.

(Prior art) Nine lights modulated by an image signal are irradiated onto a photoreceptor.
An electrophotographic printer is known that forms an image and then forms an image on recording paper in the same manner as the normal Nariko photographic method. Scanning is performed by mechanically transporting the photoreceptor.

(Problems to be Solved by the Invention) In electrophotographic printers in which sub-scanning is performed by mechanically transporting the photoreceptor, there is a problem in which wow and flutter occurs in the photoreceptor conveyance speed, causing image distortion. be.

(Problem t - Ninth Means to Solve) The above problem is solved by detecting the conveying speed of the photoconductor and writing image information into the photoconductor in synchronization with the conveyance operation of the photoconductor. .

(Function) According to the present invention, the pitch of the lines of 0 image information printed on the photoreceptor is constant regardless of the conveyance speed of the photoreceptor, and image distortion does not occur.

(Implementation f11) Below are drawings of embodiments of the present invention. I will explain while referring to it. FIG. 1 is a schematic diagram of an embodiment of the present invention.

The photoreceptor 1 is rotated by the driving means 2, and the rotation of the photoreceptor 10 at this time is detected by the photoreceptor driving state detector 3. The photoreceptor drive state detector 3 is a tachometer such as a rotary encoder, and generates a signal SA with a frequency fA proportional to the conveying speed of the photoreceptor 1. This signal SA is 7
The other input terminal of the phase comparator 5 of the Eimerotsu crew 7' (PLL) 4 receives a signal S9 of frequency fB from the voltage controlled oscillator (VCO) s, which is applied to the frequency divider 7, divided into NPs, and then inputted. Sanru. The phase comparator 5 detects the frequency difference between the input n and λ signals and generates a voltage proportional to this frequency difference. The voltage controlled oscillator 6 generates a constant signal 8B in response to input No. 1g pressure. That is, “B = NFS・f
becomes. The signal SB from PLL 4 generates an image signal!
8 is input. That is, in this embodiment, the synchronization number 16 generating means is composed of the photoreceptor driving state detector 3 and the PLL 4. The image signal generator 8 uses the signal SB as a vertical synchronization or clock signal, and generates it in a computer 9 or the like, and outputs it to the video RAM of the image processing unit 10.
The image signal held in K is sent to the optical writing element 11. Therefore, the optical writing element 11 performs optical image writing on the photoreceptor 1 in synchronization with the conveyance speed of the photoreceptor 1. In this way, the output from the photoreceptor drive state detector 3 is transferred to the PLL 4.
If the signal is supplied to the rear image signal generator 8 via t,
Even if a low-performance rotary encoder is used as the photoconductor drive state detector 3, it is possible to achieve high-precision synchronization. Since the frequency of the signal sB changes accordingly, even if the conveyance speed of the photoreceptor 1 changes, the pitch of the scanning lines does not change, and image distortion and density unevenness do not occur. In addition,
As the optical writing element, an LED array, a semiconductor F7 ray, etc. can be used.

In the configuration shown in FIG. 7, a rotary encoder with 09 pulses/rotation is used as the photoreceptor drive state detector 3, and the frequency division ratio of the frequency divider 7 is 't! 'Jps = /6, a drum-shaped gold photoconductor with a diameter gtrrcm is used as the photoconductor 1, and an IJD array is used as the light covering element 11, and the speed can be controlled every approximately 0.09° within the rotation of the drum. Rarely. This corresponds to controlling the writing speed every 61 μm on the image, and the f-lint image quality can be maintained at the city-wide level.

FIG. 3 is a schematic diagram of another embodiment of the invention.

In this embodiment, a rotary roll 1 is used as the photoreceptor 1.
2a and 12bK are stretched in the form of an endless belt. When using a belt-type photoreceptor 1 as described above, the rotation of the rotating roll 12a near the light and covering element 11 is detected and used as a vertical synchronization signal for the image signal generation 43. is preferred.

Note that the present invention relates to a thermal link using a thermal head,
It can also be applied to thermal transfer plinks and electrostatic glitter/grotters using multi-needle electrodes. In these prints, it is necessary to drive the writing target (dielectric sheet/paper) with a stepper motor and provide a standstill stage between step drives, which limits the printing speed. In addition, my friend. However, by applying the present invention to these plinks, continuous driving becomes possible.

(Effects of the Invention) In the present invention, image information is embedded on the photoconductor in synchronization with the conveyance speed of the photoconductor, so that the photoconductor f: Even when the image is forwarded by i, the pitch of the lines of image information does not change, and image distortion and density unevenness do not occur. Therefore, it is possible to use a small, lightweight, and inexpensive means for transporting the photoreceptor.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of one embodiment of the present invention, FIG. 1 is a diagram for explaining the present invention, and FIG. 3 is a schematic diagram of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... Driving means, 3... Photoreceptor small dog behavior detector, 4... PL, L. 5... Phase comparator, 6...-pressure controlled oscillator, 7
...Frequency divider, 8...-1 signal generator, 11...
- Original d-containing element island 12a, 121)...rotating roll.

Claims (3)

[Claims] (1) A synchronization signal generating means generates a synchronization signal with a frequency corresponding to the conveyance speed of the photoconductor, and by using the synchronization signal, an optical writing element writes the photoconductor in synchronization with the conveyance speed of the photoconductor. A method for controlling an electrophotographic printer characterized by performing optical image writing. (2) The first aspect of the present invention is characterized in that the synchronization signal generating means includes a rotary encoder and a phase lock loop that rotate as the photoreceptor is transported.
The electrophotographic printer control method described in Section 1. (3) A patent characterized in that the optical writing element is an LED array, and the synchronizing signal from the synchronizing signal generating means is used as a vertical synchronizing signal of the image signal generating means for supplying an image signal to the optical writing element. A method for controlling an electrophotographic printer according to claim 1.