JP2003251848A - Laser control mechanism in electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable printing quality by reducing an area of a light receiving sensor used in adjusting a light intensity of a semiconductor laser, suppressing irregularities of element outputs and eliminating output errors of a plurality of semiconductor lasers. <P>SOLUTION: In an electrophotographic apparatus which has the plurality of semiconductor lasers for generating laser lights, a waveguide for matching laser emission positions of the laser lights emitted by the semiconductor lasers to an arbitrary point by an optical fiber, a laser driving mechanism part for letting the semiconductor lasers emit light with an arbitrary laser intensity based on printing data developed to dots, an optical light receiving sensor for recognizing the light intensity of the semiconductor lasers, a mirror and a mirror driving member for guiding the laser lights to the optical light receiving sensor, and a mechanism for correcting outputs of the semiconductor lasers on the basis of information of the optical light receiving sensor, a lens is arranged at a front face of the light receiving sensor to collect the laser lights. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser control mechanism of an electrophotographic apparatus used for a printer or a copying machine. 2. Description of the Related Art A conventional technique will be described with reference to FIG.
A laser generating mechanism 106 of an electrophotographic apparatus using the semiconductor laser 101 as a light source is transmitted from a semiconductor laser 101, an optical fiber 102 for transmitting laser light emitted from the semiconductor laser, and a control mechanism (not shown). The semiconductor laser 101 is driven based on the print data obtained by dot development, and the driving amount of the semiconductor laser 101 is configured by a laser driving unit 104 based on feedback information from an optical element 105 described later. The laser light emitted from the semiconductor laser 101 is condensed by a lens (not shown) and
2 is incident. Multiple fibers 10 having the same mechanism
Numerals 2 are gathered almost in parallel and at equal intervals so that the laser emission ports are arranged in a straight line, and fixed at an arbitrary position. The laser light incident on the optical fiber 102 is emitted from the fiber outlet. The laser beam passes through a lens group (not shown), and is a mirror having a plurality of laser reflecting surfaces and rotating at a constant speed.
In step 202, scanning is performed on the surface of the photosensitive drum 204 that rotates at a constant speed. The photosensitive drum 204 is controlled at a constant speed by a control device (not shown) by a vertical synchronizing signal generated by a highly stable crystal oscillator or the like. The mirror 202 is controlled at a constant speed by the above-mentioned vertical synchronizing signal by a motor control device (not shown). Here, the print data is a dot as described above,
That is, it is constituted by an ON state in which print data is printed and an OFF state in which print data is not printed, and this determination is determined by the sensitivity of the photoconductor (not shown) to the laser and the intensity of the laser beam. That is, even in the same ON state, if the intensity of the laser beam is different, the reaction of the photoreceptor is different. The higher the laser beam intensity, the larger the print dot, and conversely, the smaller the laser beam intensity, the smaller the print dot. That is, when the intensities of a plurality of laser beams are individually varied, an output image is printed according to each laser output, so that a striped pattern appears,
This is a factor in lowering print quality. Semiconductor lasers are liable to vary in laser output in nature. For this reason, individual laser outputs need to be adjusted and feedback controlled. Particularly, in an optical system using an optical fiber, since the light emission source and the laser emission port are different, the light emission intensity at the laser emission port and the laser driving unit is reduced due to the efficiency of incidence on the fiber or the loss between the laser emission port and the like. Because of individual differences, adjustment or feedback needs to be performed on the laser beam path after the laser emission port. Therefore, an optical light receiving sensor 105 composed of a photodiode or the like for monitoring the intensity of the laser light emitted from the laser emission port was arranged, and the optical path to the optical light receiving sensor 105 was driven by the motor 201 at an arbitrary timing. Mirror 203
Then, a plurality of semiconductor lasers 101 are sequentially emitted individually, the optical receiving sensor 105 recognizes each laser beam intensity, and feeds back feedback information so that the laser beam intensity becomes a specified laser beam intensity. The method of sending to the 104 is used. However, since the laser emission port, that is, the optical fiber group, is an array of individual light emitting positions, the optical receiving sensor 105 has a physical size in which the laser emission ports are arranged so that all laser beams can be incident. It is necessary to have a size that can cover the spread of the emitted laser light. [0006] The optical light receiving sensor 1
As the light receiving area of the element 05 becomes larger, the response is delayed due to the stray capacitance of the element, and the correction time becomes longer in an arbitrary correction sequence. That is, the laser intensity cannot be recognized correctly in a short correction time, or the element sensitivity becomes lower. Since the position differs depending on the position, the correct laser intensity cannot be recognized. [0007] An object of the present invention is to eliminate print quality defects that occur when the emission intensities of a plurality of laser beams are different for the above reasons. The above object is achieved by disposing a lens on the front surface of the light receiving sensor and condensing the laser light. An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a schematic structural diagram of the optical system of the present invention. For the components described in the section of the prior art,
Description is omitted. The lens 100 is a so-called convex lens, and is disposed at a position substantially apart from the focal length on the front surface of the light receiving sensor 105. The lens has a physical diameter capable of receiving laser beams emitted from a plurality of laser emission ports. At the time of laser output correction, the motor 201
The mirror 203 is driven by a driving source such as the above, and an optical path to the light receiving sensor 105 is formed. Next, an arbitrary laser 101 is emitted, and the laser light is incident on the light receiving sensor at the focal position of the lens, the light intensity is recognized, and the current driving amount of the laser is controlled so that the required light intensity is obtained. Is done. Next, another arbitrary laser 101 emits light and is similarly incident substantially on the focal position of the light receiving sensor and controlled. By repeating this, the intensities of the plurality of laser beams are made uniform. According to the present invention, the laser beam can be monitored at substantially the same position as the light receiving sensor, and the light receiving sensor can be reduced in size. Light output can be obtained, and light response time can be shortened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic structural diagram of an optical system according to the present invention. DESCRIPTION OF SYMBOLS 100 is a convex lens, 101 is a semiconductor laser, 102 is an optical fiber, 104 is a laser drive unit, 105 is an optical light receiving sensor, 106 is a laser generation mechanism, 201 is a motor,
02 is a mirror having a plurality of reflection surfaces, 203 is a mirror driven by 201, and 204 is a photosensitive drum.

Claims (1)

Claims: 1. A plurality of semiconductor lasers for generating laser light, and a laser beam emitted from the semiconductor laser is guided by an optical fiber to align a laser emitting position at an arbitrary position. A tube, a laser drive mechanism for causing the semiconductor laser to emit laser light at an arbitrary laser intensity based on the dot-developed print data, an optical light receiving sensor for recognizing the light intensity of the semiconductor laser, and an optical light receiving sensor. In an electrophotographic apparatus having a mirror and a mirror driving member for guiding laser light, and a mechanism for correcting an output of the semiconductor laser based on information of the optical light receiving sensor, a lens is provided in front of the light receiving sensor. And condensing the laser light.
The control mechanism.