JPH02199477A - Optical head of electrophotographic printer - Google Patents

Abstract

PURPOSE:To obtain plural printing line tones and to enable printing which is superior in gradation and representation by providing spot light sources which differ in beam diameter and driving circuits which drive them, delay circuits, and a printing data control circuit for those circuits. CONSTITUTION:Printing data 1 are distributed to delay circuits 4 and 5 by a control circuit 3 with a printing control signal 2. The delay circuits 4 and 5 are set to different delay times, which are values for correcting the time differences of beams 6 and 7 on a photosensitive drum 8. The printing data which are delayed by the circuits 4 and 5 are inputted to the driving circuits 9 and 10 to drive the spot light sources 11 and 12 which are connected and differ in beam diameter. The beams 6 and 7 from the spot light sources are scanned by a rotary polygon mirror 13 to form images on a photosensitive body 8 through a cylindrical lens and an f-theta lens. Consequently, plural printing line tone are obtained and the printing which is superior in representation is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic printer, and more particularly to an optical head.

[Conventional technology]

Conventionally, the optical head of this type of electrophotographic printer has only one type of point light source.

[Problem to be solved by the invention]

Since the optical head of the conventional electrophotographic printer described above has only one type of point light source, it has the disadvantage that the distance between printed lines is monotonous.

An object of the present invention is to provide an optical head for an electrophotographic printer that solves the above problems.

[Means to solve the problem]

To achieve the above object, the present invention provides an optical head of an electrophotographic printer that reflects light from a point light source by a rotating polygon mirror and forms an image on a photoreceptor through an optical path.
A plurality of point light sources having different beam diameters, a plurality of drive circuits for driving the plurality of point light sources, a plurality of delay circuits connected to the plurality of drive circuits, and controlling print data to the plurality of delay circuits. It has a control circuit.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

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

In the figure, the optical head of the electrophotographic printer of the present invention includes a plurality of point light sources 11.12 having different beam diameters and a plurality of drive circuits 9, 10 for driving the plurality of point light sources 11.12.
, a plurality of delay circuits 4 and 5 connected to the plurality of drive circuits 9 and 10, and a control circuit 3 that controls print data to the plurality of delay circuits 4 and 5. 8 is a photoreceptor, 13
is a rotating polygon mirror, 14 is a cylindrical lens, and 15 is f
-θ lens.

Print data 1 is distributed to delay circuit 4 or delay circuit 5 by control circuit 3 according to print control signal 2 .

Each of the delay circuits 4 and 5 is set with a different delay time, and this time is a value for correcting the time difference between the beams 6 and 7 on the photosensitive drum 8.

The print data delayed by the delay circuits 4 and 5 enters a drive circuit 9 and a drive circuit 10, respectively, and drive a point light source 119 and a point light source 12 connected thereto. Note that the beam diameters of the point light sources 11 and 12 are different.

Beams 6.7 from each point light source 11.12 are scanned by a rotating polygon mirror 13 and then scanned by a cylindrical lens 14.
, an image is formed on the photoreceptor 8 via the f-θ lens 15.

〔Effect of the invention〕

As explained above, by having a plurality of point light sources with different beam diameters and their control circuits, the present invention can have a plurality of spaces between printing lines, and can obtain printing with excellent single gradation and expressiveness. effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention. 1...Print data 2...Print control signal 3...Control circuit 4, 5...Delay circuit 6
．． 7... Beam 8... Photoreceptor 9.1
0... Drive circuit 11, 12... Point light source 1
3... Rotating polygon mirror 14... Cylindrical lens 15... f-theta lens patent applicant Niigata NEC Co., Ltd.

Claims (1)

[Claims] (1) Light from a point light source is reflected by a rotating polygon mirror,
In an optical head of an electrophotographic printer that forms an image on a photoreceptor through an optical path, a plurality of point light sources having different beam diameters, a plurality of drive circuits for driving the plurality of point light sources, and a plurality of drive circuits are provided. 1. An optical head for an electrophotographic printer, comprising: a plurality of delay circuits connected to the plurality of delay circuits; and a control circuit for controlling print data to the plurality of delay circuits.