JPH07318838A - Optical scanner - Google Patents

Abstract

PURPOSE:To realize accurate adjustment by a device having simple constitution. CONSTITUTION:A semiconductor laser light source 1 is fixed on a pedestal 11 and a collimator lens 2 is stored in a lens barrel 13. The lens 2 and a cylindrical lens 4 are temporarily fixed in a holder 12 after focusing in an optical axis L direction with respect to the holder 12. A light source part unit 111 constituted in such a way is rotated around an optical axis L with respect to the holder 12 and a mounting hole 15a, so that surface tilt is corrected.

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 for forming an image in a non-impact printer, a copying machine or the like by scanning a laser beam on a photosensitive drum or the like.

[0002]

2. Description of the Related Art Conventionally, in this type of optical scanning device,
For example, as described in Japanese Patent Publication No. 62-36210, the light-modulated light beam from a light source is deflected and reflected by a reflecting surface of a rotary polygon mirror as an optical deflector, and then, a scanning lens is used to cover it. Light is guided on the scanning surface to perform optical scanning. At this time, if each reflecting surface of the rotary polygon mirror is tilted without being parallel to the rotation axis and there is an angular error, that is, a surface tilt, the scanning position of the light beam on the surface to be scanned is displaced and the final image It adversely affects the output quality.

Therefore, in the publication, in order to eliminate the adverse effect due to the surface tilt at this time, a collimated light beam from a light source by a cylindrical lens is linearly imaged on the reflecting surface of the rotary polygon mirror and scanning is performed. It has been proposed to use a toric lens as the lens so that the reflecting surface of the rotary polygon mirror and the surface to be scanned have an optical conjugate relationship.

Generally, in an optical system for correcting a surface tilt, a rotationally asymmetric optical system such as a cylindrical lens or a toric lens is used. If the accuracy of the rotational position is poor, the spot diameter cannot be narrowed down, or the spot shape becomes small. Since problems such as collapse occur, it is necessary to form the optical system with high accuracy. In particular, in the case of an optical element such as a cylindrical lens used for forming a linear image of a light flux on a rotating polygon mirror, it has a smaller size than a toric lens, so it is mounted on an optical box or the like with high accuracy. It is difficult to do so, and the optical powers in the vertical and horizontal directions are drastically different, so that the rotation accuracy around the optical axis is strictly required.

[0005]

On the other hand, in the prior art, the cylindrical lens and the optical box for mounting the cylindrical lens are manufactured with considerable accuracy, and a metal foil or the like is inserted as a spacer under the cylindrical lens so that its thickness is increased. It was very time consuming and costly because it was adjusted. Further, even when the cylindrical lens is rotated, if the actual optical axis and the center of rotation of the cylindrical lens deviate from each other, the spot shape may be deteriorated.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an optical scanning device that can perform highly accurate adjustment with a simple configuration.

[0007]

An optical scanning device according to the present invention for achieving the above object linearly images a light beam from a light source onto a deflector via a first optical system, In an optical scanning device which scans a light beam deflected by the deflector onto a predetermined surface via a second optical system, the first optical system has a structure capable of rotating about its optical axis during adjustment. It is characterized by

[0008]

In the optical scanning device having the above-described structure, the light beam from the light source is linearly imaged on the deflector, and the first optical system is rotated integrally with the light source around the optical axis or the light source. Part is fixed and the first optical system is rotated about the optical axis to adjust the first optical system with high accuracy with respect to the actual optical axis, and the light beam is repeated on the scanned surface. To scan.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. 1 and 2 show a first embodiment, FIG. 1 shows a scanning cross section that is a surface that includes an optical axis and is formed by a scanning beam over time, and FIG. 2 shows a surface that includes the optical axis and is perpendicular to the scanning cross section. 3 is a configuration diagram viewed from the sub-scanning cross section.

A collimator lens 2, an aperture stop 3, a cylindrical lens 4 and a rotary polygonal mirror 5 are arranged in front of the semiconductor laser light source 1, and an imaging lens 6 for correcting the focusing property in the reflection direction of the rotary polygonal mirror 5, An image forming lens 7 and a photosensitive drum 8 that correct the scanning linearity are arranged.

The light beam emitted from the semiconductor laser light source 1 is made into substantially parallel light by the collimator lens 2, passes through the aperture stop 3, and the size of its cross section is adjusted. The light beam that has become parallel light is focused only in the sub-scanning direction, which is the cross-sectional direction of FIG. 2, by passing through the cylindrical lens 4, and becomes a focal line to enter the deflecting surface of the rotary polygon mirror 5. . The rotary polygon mirror 5 rotates at high speed in the direction of the arrow in FIG. 1, and the incident light beam is deflected and scanned at high speed.

The light beam reflected by the line segment P on the reflecting surface of the rotary polygonal mirror 5 has its focusing property and scanning linearity, that is, f.theta.
The upper part is repeatedly scanned in the direction of the arrow at a constant speed. At this time,
Since the photoconductor drum 8 rotates by a predetermined amount in the sub-scanning direction, the light beam modulated by the image data can form a two-dimensional image on the photoconductor drum 8.

FIG. 2 shows that the optical conjugate relationship in the main scanning section of FIG. 1 is different from the conjugate relationship in the sub scanning section. Regarding the cross section of FIG. 2, the cylindrical lens 4
The image forming point X is made to come on the reflection line segment P, and the image forming point X and the point A on the photosensitive drum 8 are optically conjugated by the image forming lenses 6 and 7. Therefore, the optical system is configured so as not to cause the position variation at the point A even if the deflecting and reflecting surface of the rotary polygon mirror 5 is tilted.

FIG. 3 is a sectional view of the mounting structure of the semiconductor laser light source 1, the collimator lens 2, the aperture stop 3, and the cylindrical lens 4, and FIG. 4 is a perspective view including the rotary polygon mirror 5. The semiconductor laser light source 1 is fixed to a base 11, and the base 11 is fixed to a holder 12. The collimator lens 2 is housed in the lens barrel 13 together with the aperture stop 3 and mounted in the holder 12, and is fixed to the holder 12 after the focus adjustment in the optical axis L direction is completed. Similarly, the cylindrical lens 4 is also fixed to the holder 12 after the focus adjustment in the optical axis L direction is completed.

The semiconductor laser light source 1, the base 11, the holder 12, the collimator lens 2, the aperture stop 3, the lens barrel 13, and the cylindrical lens 4 form a single light source unit 14, which includes a rotary polygon mirror 5 and an image forming unit. The lenses 6 and 7 are fixed in the light source unit mounting holes 15a of the optical box 15, and the light source unit 14 is mounted in the mounting holes 15 as shown in FIG.
It can be rotated about the optical axis L in the arrow direction with respect to a within a range of about 2 ° to 3 °.

A rotation error about the optical axis caused by a manufacturing error or a mounting error of the cylindrical lens 4 can be corrected by the above rotation of the light source unit 14. Therefore, it is possible to eliminate the deterioration of the image forming spot on the scanning surface due to the rotation of the cylindrical lens 4, and it is possible to stably form an image of a high-performance minute spot.

Further, since the collimator lens 2 and the cylindrical lens 4 are integrated and fixed on the same holder 12, it is structurally simple, and the cylindrical lens 4 rotates on the actual optical axis L with high precision. Since it is possible, fine adjustment is also possible. In this case, the position of the light beam passing through the cylindrical lens 4 does not change at all even if the cylindrical lens 4 is rotated.

The base 11 to which the semiconductor laser light source 1 is attached is fixed to the holder 12 and is rotatable with the holder 12. However, the base 11 is separate from the holder 12 so that the semiconductor laser light source 1 does not rotate. You may

It is also possible to realize an optical system for rotation adjustment by replacing the optical members of the collimator lens 2 and the cylindrical lens 4 with a single anamorphic toric lens or the like.

FIG. 5 shows the light source unit 14 of the second embodiment.
FIG. 6 is a perspective view including the rotary polygon mirror 5.
The cylindrical lens 4 is fixed to the lens barrel 16,
The lens barrel 16 is rotatably fitted in a holder 17.

Therefore, the focus adjustment in the optical axis L direction by the axial movement of the lens barrel 16 with respect to the holder 17 and the rotation adjustment around the optical axis L can be performed, and the cylindrical lens 4 is independently adjusted. This is effective for making fine adjustments.

FIG. 7 shows a third embodiment. In the first embodiment, the rotation adjustment is performed after the light source unit 14 is inserted into the mounting hole 15a of the optical box 15, but in this embodiment, the rotation adjustment is performed.
As shown in (a) and (b), the light source unit 14 is rotatably mounted on the V groove 18 and the U groove 19 provided in the optical box 15.

Therefore, the V groove 18 of the light source unit 14 is
Focus adjustment and rotation adjustment can be performed by movement in the direction of the optical axis L with respect to the U groove 19 and rotation about the optical axis L, and it may be fixed after the adjustment.

[0024]

As described above, the optical scanning device according to the present invention forms the light beam from the light source on the deflector.
By rotating the optical system of (1) together with the light source unit or separately from the light source unit and adjusting the tilt accurately with respect to the actual optical axis, it is also applicable to adjustment of a high-performance scanner with a small spot. Since it is structurally simple, the cost is low.

[Brief description of drawings]

FIG. 1 is a configuration diagram as seen from a main scanning section of a first embodiment.

FIG. 2 is a configuration diagram viewed from a sub-scan section.

FIG. 3 is a cross-sectional view of a light source unit.

FIG. 4 is a perspective view.

FIG. 5 is a sectional view of a light source unit according to a second embodiment.

FIG. 6 is a perspective view.

FIG. 7 is a perspective view of a light source unit according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser light source 2 Collimator lens 3 Aperture stop 4 Cylindrical lens 5 Rotating polygonal mirror 11 Base 12, 17 Holder 13, 16 Lens barrel 14 Light source unit 15 Optical box 18 V groove 19 U groove

Claims (2)

[Claims] 1. A light beam from a light source is linearly imaged on a deflector via a first optical system, and the light beam deflected by the deflector is directed to a predetermined surface via a second optical system. An optical scanning device for scanning upward, wherein the first optical system has a structure capable of rotating about the optical axis thereof during adjustment. 2. The optical scanning device according to claim 1, wherein the first optical system includes a cylindrical lens.