JP2000231067A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-beam optical scanner capable of moderating the positional accuracy and the machining accuracy of a slit member and easily adjusting the beam diameters of two laser beams. SOLUTION: This scanner is provided with a light source 3 generating two laser beams 1 and 2, a parallel beams forming means 4 collimating two laser beams 1 and 2 from the light source 3 and emitting them, an optical member 6 arranged on a downstream side in a beam advancing direction with respect to an intersection formed by two parallel beams from the means 4, the slit member 5 shielding one part of two laser beams passing through the member 6, and optical means (7, 8) guiding two laser beams passing through the member 5 to a deflecting means 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used as means for recording and forming an electrostatic latent image on the surface of a photoreceptor in an electrophotographic apparatus such as a laser printer and a copying machine.

[0002]

2. Description of the Related Art In an optical scanning apparatus for recording and forming an electrostatic latent image on the surface of a photoreceptor in an electrophotographic apparatus, two laser beams are scanned on the photoreceptor to form an electrostatic latent image on the surface of the photoreceptor. A so-called two-beam optical scanning device configured to perform this operation is known and has been put to practical use.

[0003] In recent years, in the field of electrophotographic apparatuses, there has been an increasing demand for higher definition of a printed image in addition to higher printing speed. The diameter must be reduced to about 70 μm.

For example, according to Japanese Patent Application Laid-Open No. Hei 6-208068, two laser beams emitted from a laser diode array are collimated by a collimator lens, and a slit member is formed at a portion where the two parallel beams intersect. A configuration is disclosed in which a beam area unnecessary for recording an electrostatic latent image is shielded by passing two parallel lights through the slit member to adjust the beam diameter.

[0005]

SUMMARY OF THE INVENTION However, Japanese Patent Laid-Open No.
In the case where the slit member is arranged at a portion where two parallel lights intersect as in the configuration disclosed in Japanese Patent Publication No. 2008068, the accuracy of the mounting position of the laser diode array and the distance between the laser diode array and the slit member are set. Variations are likely to occur in the intersection position of the parallel light due to the accuracy of the provided collimator lens and the like. Is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a two-beam optical scanning device capable of relaxing the positional accuracy and processing accuracy of a slit member and easily adjusting the beam diameter of two laser beams.

[0007]

The object of the present invention is to provide a light source for generating two laser beams, a parallel light forming means for converting the two laser beams from the light source into parallel light, and outputting the parallel light. An optical member provided on the downstream side in the beam traveling direction with respect to an intersection formed by the two parallel lights from the forming unit, a slit member for shielding a part of each of the two laser beams passing through the optical member, Optical means for guiding the two laser beams passing through the slit member to a deflecting means.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of the optical scanning device of the present invention. The two laser beams 1 and 2 emitted from the laser diode 3 are adjusted to substantially parallel light by a collimator lens 4 serving as a parallel light forming means, and are subordinate to the two laser beams by a cylinder lens 6 serving as an optical member. Only the beam diameter in the scanning direction (hereinafter, referred to as “vertical diameter”) is narrowed, and immediately after that, a slit member 5 is disposed, and as shown in FIG. (Hereinafter referred to as “horizontal diameter.”) After shielding about 30% of the light from each side, the laser beam is narrowed down through the cylinder lens 7 and the cylinder lens 8 to form an image on a polygon mirror 9 serving as a deflection unit. After scanning, it is scanned.

The laser beams 1 and 2 scanned by the polygon mirror 9 spread again on the Fθ lens 10, are again stopped down, are reflected by the return mirror 11, are reflected by the return cylinder 11, and have only the longitudinal diameter set by the long cylinder lens 12. It is further narrowed down and scanned on the surface of the photoconductor 13.

FIG. 2 is an explanatory diagram showing the relationship between the slit member 5 and the laser beams 1 and 2 as viewed from the direction AA in FIG. In such a configuration, the amount of blocking the laser beam is inside the light intensity 1 / e ² = 0.135 (beam spot diameter on the surface of the photoconductor) with respect to the lateral diameter, and is more than the light intensity 1/2. In order to adjust the pitch in the scanning direction between the laser beam 1 and the laser beam 2 in the vertical direction, it is necessary to move in the vertical direction. Configuration.

In consideration of the above, in the optical scanning device of the present invention, the opening 5a of the slit member 5 is shielded so as to block approximately 30% of the maximum diameter of the parallel light after passing through the collimator lens 4.
Was placed. Therefore, unnecessary light can be almost blocked by the slit member 5 without requiring fine adjustment of the position of the slit member 5, and the beam spot diameter can be easily adjusted.

[0012]

As described above, according to the present invention, the position accuracy and processing accuracy of the slit member can be reduced, and the beam diameter of the two laser beams can be easily adjusted. Can be provided.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an optical scanning device according to the present invention.

FIG. 2 is a view taken along the line AA of FIG. 1;

[Description of Signs] 1, 2 laser beam, 3 laser diode, 4 collimator lens, 5 slit member, 6, 7, 8 cylinder lens, 9 polygon mirror, 10 fθ lens, 1
DESCRIPTION OF SYMBOLS 1 ... Return mirror, 12 ... Long cylinder lens, 13
... Photoconductor.

Claims (2)

[Claims] 1. A light source for generating two laser beams,
Parallel light forming means for converting two laser beams from the light source into parallel light and emitting the light, and an optical member provided on the downstream side in the beam traveling direction with respect to an intersection formed by the two parallel lights from the parallel light forming means A slit member that shields a part of each of the two laser beams that have passed through the optical member, and an optical unit that guides the two laser beams that have passed through the slit member to a deflecting unit. Optical scanning device. 2. The optical scanning device according to claim 1, wherein the optical member is a cylinder lens that narrows only the beam diameter of the two laser beams in the sub-scanning direction.