JPS63266419A - Scanner - Google Patents

Abstract

PURPOSE:To provide a higher speed, longer life and better scanning accuracy and to widen a scanning width with a short optical path length by forming a mirror face to a plane inclusive of the central axis of rotation of a shaft which is rotationally supported by gas bearings. CONSTITUTION:The cylindrical shart 1 supported by the gas bearings 2 is rotated at a high speed by a driving means 3. the mirror face 4 is formed on the plane inclusive of the central axis of rotation of the end face side of the shart 1. High-speed scanning of a light beam is thereby executed without contact with the revolving shaft and the wider scanning width can be taken. The deviation in the scanning position by a difference in the accuracy of a surface tilt in the case of a polygonal mirror is eliminated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a beam scanning scanner for an optical device that uses laser light or the like, and in particular has a large swing angle, a short optical path and a long scanning width, and The present invention relates to a structure of a scanner suitable for cases where a long life is not required.

[Conventional technology]

Conventional scanners used for scanning laser beams and the like include a galvano-mirror type scanner that scans light by reciprocating a plane mirror attached to a shaft by a driving means, and one type described in Japanese Patent Application Laid-open No. 169074/1983, for example. There was one type of polygon mirror, which rotated a polygon mirror at high speed in one direction to scan the source.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology has the following troublesome problems.

That is, in the one-type galvano mirror, the speed is not increased because it is first moved by reciprocating motion, and at present, when swinging a mirror that is about 30W square, it is generally about 100H2. Moreover, the scanning speed is not constant, and since the speed can be considered to be approximately constant, only a small portion of the actual swinging range can be used. Furthermore, the life of the shaft support system (rolling bearing life) was also short.

Because the polygon mirror one-way type rotates in one direction.

It is possible to increase the speed. However, since the geometric precision (surface inclination) of the valley plane mirror with respect to the rotation axis is not uniform, there is a problem that the scan position shifts on each surface. Since the surface of the nine-plane mirror is far from the center of rotation, compared to the case where the mirror is oscillated at the center of rotation, as in the case of a one-sided galvano mirror,
For the same optical path length, there was a frequent problem that the width was too wide.

The object of the present invention is to eliminate the problems of the prior art described above.

It is an object of the present invention to provide a scanner 1 that is fast, has a long life, has a good scanning density, and has a short optical path length and a wide scanning width.

[Means for solving the problem] The above purpose is achieved as follows. First, in order to achieve high speed rotation and long life, it is supported by a straight air bearing. Furthermore, the mirror is formed near the center of the shaft so that the scanning width can be widened for the same optical path length. Katsu- only face Mi-t-
By making W, it is possible to eliminate the deviation of the scanning position due to the WII degree of surface inclination of each mirror surface, which is a problem with polygon mirrors. If the symmetry of the shaft is a problem in achieving high-speed rotation, the mirror surfaces are arranged near the center of the shaft in two-sided symmetry.

[Effect]

Gas bearings have low loss and excellent high-speed stability.
A shaft that rotates at high speed can be realized.

By forming the mirror integrally with the shaft on a surface that includes the rotational axis of the shaft, the rotational center of the mirror surface and the rotational center of the shaft can be made to coincide or be very close to each other, so that a large scanning width can be obtained.

′! If a mirror is formed on only one surface including the rotation center axis of the shaft, scanning deviations due to differences in surface irregularity of each surface, which is a problem with polygon mirrors, will not occur. -! In order to perform high-speed rotation, it is desirable that the shaft be symmetrical about the rotational axis, so in this case, two mirror surfaces may be formed around the rotational axis. At this time, if the inclination of the two mirror surfaces becomes a problem, scanning of only the negative surface may be enabled, or the negative surface may be made non-reflective.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a cylindrical shaft 1 is supported by a gas bearing 2 and driven by a drive means 3. The drive can be either rotation or oscillation, but in order to achieve higher speeds, the rotation method is the best. The mirror 4 can be realized by cutting one end of the shaft 1 in half to give it a mirror surface as shown in the figure.

FIG. 2 shows another embodiment of the present invention. This embodiment is a simplified example of a mirror sword, in which the end face of the shaft 1 is cut obliquely, and a mirror 5 is formed on this cut face.

3 and 4 respectively show still other embodiments of the present invention, and these embodiments are examples in which the shaft 1 is symmetrical about the rotational axis in consideration of stability tJ against high-speed rotation. Figure 43 shows an example in which two 5ft mirrors are formed symmetrically with the rotational axis of the shaft 1 as shown in Figure 2, and Figure 4 is the same as that shown in Figure 1! This is an example in which two mirrors 4t of ii are formed.

If surface inclination accuracy is a problem, only the inner surface of the formed two-sided mirror should be scanned effectively, or the inner surface alone is 1 kg! However, if the surface and the pair are treated with non-reflective treatment, it will be fine. These mirrors have a shaft made of aluminum and can be manufactured completely integrally with the shaft by applying direct surface processing to the end face thereof, so that a simpler and more compact configuration than conventional examples is possible.

〔Effect of the invention〕

According to the present invention, since the shaft (7) formed integrally with the mirror can be rotated at high speed in a non-contact manner, it is possible to perform high-speed scanning with a light beam with a long life (semi-permanent). In addition, since the mirror surface can be formed integrally with the rotation shaft on the surface that includes the rotation axis, the optical path length is larger than that of a polygon mirror type in which the mirror surface is placed at a point far from the center of rotation. This has the effect of increasing the scanning width. Furthermore, by using only one mirror surface, it is possible to eliminate the deviation of the scanning position due to the difference in surface irregularity accuracy of the valley mirror, which is a drawback of polygon mirrors.

[Brief explanation of the drawing]

1 to 4 are perspective views, partially in cross section, of an embodiment of the scanner of the present invention. 1...Shaft, 2...Gas bearing, 3...Drive unit, 4゜%+Cause 20 3-Jfl force calendar P 4.5゛-? Ra

Claims (1)

[Claims] 1. In a scanner that scans light such as a laser beam,
A scanner comprising: a shaft supported by a gas bearing; driving means for driving the shaft; and a mirror surface made integrally with the shaft. 2. The scanner according to claim 1, wherein the mirror surface is a plane including the rotation center axis of the shaft. 3. The scanner according to claim 1, wherein the mirror surface is a cut surface obtained by cutting the end of the shaft obliquely with respect to the central axis of rotation. 4. The scanner according to claim 1, wherein the mirror surface has two surfaces arranged symmetrically with respect to the shaft center axis.