JP2658981B2 - Scanning optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device for scanning a laser beam, and more particularly to a scanning optical device using a polygon mirror.

[0002]

2. Description of the Related Art Conventionally, a scanning optical device includes a light source for generating a laser beam, a polygon mirror for scanning the laser beam, a motor for rotating the polygon mirror at a constant speed, and a laser beam reflected from the polygon mirror. It has an fθ lens for condensing light on a scanning line, and a chassis for fixing these optical systems. The size of the polygon mirror is determined when the fθ lens is designed, and its shape and position need to be maintained with high precision.
The fixing position is limited to one place.

[0003]

In the conventional scanning optical device, when the scanning speed is increased, the number of reflecting surfaces of the polygon mirror may be increased. However, when a polygon mirror having an increased number of reflecting surfaces is used, If the fixed position is the same as the fixed position of the original polygon mirror having a smaller reflecting surface, the incident position of the laser beam to the fθ lens is shifted, and optical performance cannot be obtained. Therefore, since it is not possible to replace the polygon mirror with an increased number of reflection surfaces, conventionally, the only option was to increase the speed of the motor.

However, in order to increase the speed of the motor, the bearing used for the mechanism for rotating the polygon mirror must be changed from a ball bearing to an air dynamic pressure bearing.
Significant cost increase.

It is an object of the present invention to provide a scanning optical device having a configuration that allows for a future increase in the speed of a scanning optical system.

Another object of the present invention is to provide a scanning optical device which can easily replace a polygon mirror having an increased number of reflecting surfaces according to a scanning speed.

[0007]

According to the present invention, a light source for emitting laser light, a polygon mirror for scanning the laser light from the light source, a motor for rotating the polygon mirror at a constant speed, and a polygon mirror are provided. It has an fθ lens for condensing the reflected laser light on one scanning line, and a chassis for fixing the light source, the motor and the fθ lens. The chassis has at least two types of polygon mirror mounting positions. At least two positioning holes are formed at positions where a part of the holes overlaps, and a motor with a corresponding polygon mirror is inserted and fixed in one of the two or more positioning holes. A scanning optical device is obtained.

[0008]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are plan views of an embodiment of the present invention. FIG. 1 is a plan view when a five-sided polygon mirror is used, and FIG. 2 is a plan view when a six-sided polygon mirror is used. is there. 1 and 2, common parts are used except for the polygon mirror. Each optical component is fixed on one chassis 7.

In FIG. 1, laser light emitted from a light source 1 is focused by a toroidal lens 2 and enters a five-sided polygon mirror 3. The five-sided polygon mirror 3 has five reflecting surfaces, and its axis is fixed to a motor 4 (indicated by a dashed line in FIGS. 1 and 2) and rotates at a constant speed. This rotation reflects and scans the laser light.

FIG. 3 is a plan view showing a state where the five-sided polygon mirror 3 is mounted on the motor 4, FIG. 4 is a side view, and FIG. 6 is a rear view. The five-sided polygon mirror 3 is fixed to a shaft of the motor 4 by a washer 11 and a leaf spring 12. The leaf spring 12 is pressed against a shallow dent 13 formed on the upper surface of the five-sided polygon mirror 3 via the five projections at its tip. The motor 4 is fixed to a fixing member 42, and the fixing member 42 is fixed to the substrate 41. A drive circuit for driving the motor 4 is mounted on the board 41. Fixing member 4
Reference numeral 2 denotes a cylindrical body integrally fixed to the motor 4,
Protruding to the back side of the. At four corners of the board 41, fixing holes 43 for screwing to the chassis 7 are formed.

FIG. 6 is a plan view showing the chassis 7. A first positioning hole 71 and a second positioning hole 72 partially overlapping the hole 71 are formed in the chassis 7.
Four screw holes 73 and four screw holes 4 for fixing the substrate 41
3 and four screw holes 74 at the off positions are formed. In FIG. 1, a fixing member 42 of the motor 4 to which the five-sided polygon mirror 3 is fixed is inserted and fixed in a first positioning hole 71 of the chassis 7. At this time, the substrate 41
It is screwed by the screw hole 73. On the other hand, as shown in FIG. 2, a fixing member 42 (common to FIGS. 4 and 5) of the motor 4 to which the six-sided polygon mirror 8 is fixed is inserted and fixed in the second positioning hole 72. At this time, the substrate 41 is screwed into the screw hole 74.

The laser light reflected from the five-sided polygon mirror 3 and the six-sided polygon mirror 8 is incident on the first fθ lens 5 and further incident on the second fθ lens 6, so that one scan of an irradiation body (not shown) is performed. It is focused on the line.

In this embodiment, the positions of the first and second positioning holes 71 and 72 are determined when the motor 4 to which the five-sided polygon mirror 3 is fixed and the motor 4 to which the six-sided polygon mirror 8 is fixed are fixed. Is determined such that desired optical characteristics can be obtained. When the scanning positions on the irradiation body are made substantially the same, the position of the six-sided polygon mirror 8 is set farther from the fθ lens, and a larger diameter than the five-sided polygon mirror 3 is used as the six-sided polygon mirror 8. In this case, the scanning speed can be increased simply by fixing the motor 4 to which the six-sided polygon mirror 8 is fixed in place of the five-sided polygon mirror 3 in the second positioning hole 72, so that the scanning speed conversion can be performed in a very short time. it can.

In this embodiment, the first and second positioning holes are circular. However, as shown in FIG. 7, rectangular positioning holes 75 and 76 may be partially overlapped. The shape is not particularly limited. In addition, the number of positioning holes in the chassis is 3 depending on the polygon mirror to be used in the future.
More than one may be provided.

[0016]

As described above, according to the present invention, the motor can be positioned in two places. Therefore, in the case of high speed operation, the number of polygon mirror surfaces is increased to use a large polygon mirror, and the motor bearing is used. Etc. can be realized with specifications that do not increase the cost, and the manufacturing schedule can be shortened because there is no design change.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a plan view when a five-sided polygon mirror is used.

FIG. 2 shows an embodiment of the present invention and is a plan view when a six-sided polygon mirror is used.

FIG. 3 is a plan view showing a state in which a five-sided polygon mirror is fixed to a motor.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a rear view of FIG. 4;

FIG. 6 is a plan view of a chassis used in the embodiment of the present invention.

FIG. 7 is a plan view showing another example of the chassis used in the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 light source 2 toroidal lens 3 5-sided polygon mirror 4 motor 5 first fθ lens 6 second fθ lens 7 chassis

Claims (3)

(57) [Claims] 1. A light source for emitting laser light, a polygon mirror for scanning the laser light, a motor for rotating the polygon mirror at a constant speed, and a laser light reflected from the polygon mirror on one scanning line. In a scanning optical device having an fθ lens for condensing light, and a chassis for fixing the light source, the motor and the fθ lens, a hole is formed in the chassis at a position corresponding to a mounting position of at least two types of polygon mirrors. At least two positioning holes partially overlapping each other are formed, and a motor having the corresponding polygon mirror is inserted and fixed in one of the two or more positioning holes. . 2. The scanning optical device according to claim 1, wherein the motor is fixed to a substrate on which a motor drive circuit is mounted, and a fixing member inserted and fixed in the positioning hole is fixed on a back side of the substrate. . 3. The scanning optical apparatus according to claim 1, wherein the two or more positioning holes are circles partially overlapping each other.