JPH07318841A - Rotating polygon mirror - Google Patents

Abstract

PURPOSE:To provide a rotating polygon mirror used in a laser scanning optical system or the like capable of making noise made in the case of rotation very small. CONSTITUTION:The upper and lower parts of a polygon mirror rotating body 1 are held by thin plate disk members 3, and an inclination part 3a is formed on the periphery of the member 3. The angle theta of the inclination part is set to 0 deg. to 30 deg.. By assembling the rotating polygon mirror having such constitution in the laser scanning optical system and rotating it at specified rotating speed, mirror impulse wave 5 is generated from the corner part of the mirror surface part 2 of the rotating body 1. However, the impulse wave 5 is restrained from being released suddenly to the outside by the inclination part 3a. As a result, the noise made by the rotating body 1 is drastically softened. It is good to form a step-like enlarging part, a curvature enlarging form part or a circular-arc form part instead of the inclination part 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary polygon mirror used in a laser scanning optical system or the like, and more particularly to a rotary polygon mirror which reduces noise during rotation.

[0002]

2. Description of the Related Art A conventional rotary polygon mirror 30 is shown in FIG.
As shown in (b), the mirror surface portion 31 has a polygonal outer periphery. Therefore, when the rotary polygon mirror 30 rotates at a high speed, the corner portion 32 disturbs the air around the mirror surface portion 31 to generate noise 33. Here, FIG. 5A is a plan view of an example of a conventional rotary polygon mirror 30, and FIG. 5B is a side view thereof.

A proposal for alleviating this noise is made, for example, in Japanese Patent Application Laid-Open No. 58-139101. In this proposal, as shown in the rotary polygon mirror 34 of FIG. 6, the wall thickness T1 of the mirror surface portion 31 of the conventional rotary polygon mirror 30 is thinned to T0 (here, 1 to 2 mm <T0 <T1). In order to prevent the reduction of the rotational rigidity of the mirror surface portion of the rotary polygon mirror 34 caused by this, a cylindrical reinforcing portion 35 slightly smaller than the inscribed circle of the mirror surface portion is provided on both side surfaces thereof. According to the proposed rotary polygon mirror 34, since the wall thickness T0 of the rotary polygon mirror 34 is thin, the ratio of the air being disturbed by the corners of the mirror surface portion is reduced accordingly and the noise is reduced. be able to.

[0004]

However, there is a limit to reducing the wall thickness T0 of the mirror surface portion of the rotary polygon mirror 34, and the laser light is once focused on the mirror surface using the surface tilt correction optical system. However, if the beam diameter is set to 10 μm and the mounting error between the mirror surface and the optical axis and the effective reflection surface width in processing are taken into consideration, the wall thickness T0 of the mirror surface portion of the rotary polygon mirror 34 is 1 to 2 mm.
Need a place. When the rotating polygon mirror 34 having a thickness of about 1 to 2 mm is provided with a cylindrical reinforcing portion 35 as shown in FIG. 6 and rotated at a predetermined rotation speed, the generated noise is generated by the rotating polygon mirror shown in FIG. Although it is smaller than the noise generated by No. 30, there is a problem that the noise is still insufficient.

An object of the present invention is to eliminate the above-mentioned problems of the prior art and to provide a rotary polygon mirror used in a laser scanning optical system or the like which can sufficiently reduce noise during rotation.

[0006]

In order to achieve the above object, the invention of claim 1 is a rotary polygon mirror used in a laser scanning optical system or the like, wherein a polygonal mirror rotating body having an outer peripheral portion having a polygonal mirror surface. And a thin plate disk portion which is fixed to both upper and lower surfaces of the polygon mirror rotating body, is concentric with the polygon mirror rotating body, and has a diameter larger than the circumscribed circle of the polygon mirror rotating body.

Further, in the invention of claim 2, the outer diameter dimension of the thin plate disk portion has a value in the range of 3 times to 10 times the difference between the inscribed circle dimension and the circumscribed circle dimension of the mirror surface portion. The feature is that the size is set to the size of the inscribed circle of the mirror surface.

Further, according to the invention of claim 3, any one of an inclined portion, a step-shaped enlarged portion, a curved enlarged shape portion, and an arc-shaped portion of which the outer side of the polygonal disk rotor of the thin plate disk portion spreads outward. The feature is that it is shaped like.

[0009]

According to the present invention, when the rotary polygon mirror is rotated at a predetermined high speed, a mirror shock wave generated at a corner portion of the rotary polygon mirror causes a polygon mirror rotating body of the thin disk portion. It is mitigated by the outer facing portion, and the noise level is greatly suppressed. As a result, a quiet laser scanning optical device can be provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. 1A and 1B are a plan view and a sectional view taken along line XX of a rotary polygon mirror according to an embodiment of the present invention.

In the figure, reference numeral 1 is a polygon mirror rotating body, and 2 is a mirror surface portion thereof. Reference numeral 3 denotes a thin disk member that sandwiches both sides of the polygon mirror rotating body 1 and has a diameter larger than the circumscribed circle of the polygon mirror rotating body 1. Reference numeral 4 denotes the rotation center of the rotating polygon mirror. In the vicinity of the outer peripheral portion of the thin plate disk member 3, as shown in the drawing, there is an inclined portion 3a which is open outward. The thin disk member 3 may be made of a material such as plastic or aluminum that is lightweight and has good workability. Further, the inner surface thereof may be coated with a material that absorbs or scatters air vibrations, for example, carbon having irregularities on the surface.

In the figure, D is the diameter of the thin disk member 3, D1 is the diameter of the inscribed circle of the polygon mirror rotating body 1, and D2 is the polygon mirror rotating body 1.
Is the diameter of the circumscribed circle, D3 is the difference between the diameter D2 of the circumscribed circle and the diameter D1 of the inscribed circle, and D4 is the diameter of the bending position where the outer peripheral portion of the thin disk member 3 is inclined. The polygon mirror rotating body 1 and the center of rotation 4 of the thin disk member 3 are configured to coincide with each other. Further, 5 indicates a specular shock wave, and 6 indicates a traveling direction of the specular shock wave 5.

Next, assuming that the thickness of the mirror surface portion 2 is T1 and the size of the opening of the outermost peripheral portion between the thin disk members 3 is T2, the dimension D of each part of the mirror surface portion 2 and the thin disk member 3 is D4 and T2 are each configured to satisfy the following relationship.

3 × D3 + D1 ≤D≤10 × D3 + D1 (1) D2 ≤D4 ≤D (2) T1 ≤T2 ≤2 × T1 (3) Further, the thickness T1 of the mirror surface portion 2 is approximately 1 to 1. The bending angle Θ of the inclined portion 3a is 2 mm, and the bending angle Θ is 0 ° ≦ Θ ≦ 30 °, preferably 10 ° to 20 °. Further, D in the formula (1) is preferably (5 × D3
The configuration is such that the conditions of + D1) to (8 * D3 + D1) are satisfied.

In this embodiment, when the polygon mirror rotating body 1 and the thin disk member 3 are rotated at a predetermined rotation speed,
As shown in (b), the specular shock wave 5 is generated by the corner portion of the polygon mirror rotating body 1. However, in this embodiment, since the inclined portions 3a of the thin plate disk member 3 extend in the peripheral portions on both the upper and lower sides of the polygonal mirror rotating body 1, the specular shock wave 5 suddenly moves from the periphery of the specular surface portion 2 to the outside. The release is stopped. In other words, the mirror shock wave 5 is gradually released and is absorbed and relaxed by the thin disk member 3 as the polygon mirror rotating body 1 is moved away from the polygon mirror rotating body 1 in the radial direction. As a result, noise generated when the polygon mirror rotating body 1 rotates can be greatly reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that a stepped enlarged portion 3b is provided instead of the inclined portion 3a of the thin disk member 3 of the first embodiment. 2 that are the same as or equivalent to those in FIG. 1 indicate the dimensions D, D1, D2, D3 and D.
It is assumed that 4 satisfies the conditions of the above expressions (1) to (3).

Also in this embodiment, when the polygon mirror rotating body 1 is rotated at a predetermined rotation speed, the mirror shock wave 5 is generated by the corner portion of the mirror surface portion 2. The mirror shock wave 5 is the stepped expanding portion 3b. The sudden release to the outside can be stopped by.

Next, a third embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that a smooth curved enlarged shape portion 3c is provided instead of the inclined portion 3a of the thin disk member 3 of the first embodiment.

FIG. 4 shows a fourth embodiment of the present invention.
The feature of this embodiment is that an arc-shaped portion 3d is provided instead of the inclined portion 3a of the thin disk member 3 of the first embodiment. In addition, in the third and fourth embodiments, the above (1) to
The condition of Eq. (3) is satisfied.

In the third and fourth embodiments as well, similar to the first embodiment, the mirror shock wave 5 generated when the polygon mirror rotating body 1 is rotated at a predetermined rotation speed is rapidly emitted to the outside. Can be reduced by the curved enlarged shape portion 3c or the arc-shaped portion 3d. As a result, noise generated by the polygon mirror rotating body 1 to the outside can be greatly reduced.

[0021]

According to the first aspect of the present invention, it is possible to prevent the specular shock wave generated when the polygon mirror rotating body rotates at a predetermined high speed from being suddenly emitted to the outside. As a result, there is an effect that the noise generated by the polygon mirror rotating body can be significantly reduced. Further, there is an effect that the noise can be greatly reduced by a simple and inexpensive means.

According to the second aspect of the present invention, the outer diameter of the thin plate disk portion is set to the difference of 3 between the inscribed circle dimension and the circumscribed circle dimension of the mirror surface portion.
Since it is set to be not less than 10 times and not more than 10 times, it is possible to more effectively reduce the noise generated by the polygon mirror rotating body.

Further, according to the invention of claim 3, since the outer side of the thin plate disk portion is processed so as to expand, the noise can be effectively controlled.

[Brief description of drawings]

FIG. 1 is a plan view and a sectional view taken along line XX of a first embodiment of the present invention.

FIG. 2 is a sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view of a third embodiment of the present invention.

FIG. 4 is a sectional view of a fourth embodiment of the present invention.

FIG. 5 is a plan view and a side view of a conventional polygon mirror rotating body.

6A and 6B are a plan view and a side view of a conventional example in which noise of a conventional polygon mirror rotating body is mitigated.

[Explanation of symbols]

1 ... Polyhedral mirror rotating body, 2 ... Mirror surface part, 3 ... Thin disk member, 3
a ... inclined part, 4 ... center of rotation, 5 ... specular shock wave, 6 ... traveling direction of specular shock wave, 3b ... stepped expanded part, 3c ... curved expanded shape part, 3d ... arc shaped part.

Claims (3)

[Claims] 1. A rotary polygon mirror used in a laser scanning optical system or the like, wherein a polygon mirror rotating body having an outer peripheral portion having a polygonal mirror surface, and the polygon mirror rotating member fixed to both upper and lower surfaces of the polygon mirror rotating body. A thin disk part that is concentric with the body and has a diameter larger than the circumscribed circle of the polygonal mirror rotating body. A rotating polygon mirror characterized by being relaxed by a part. 2. The rotary polygonal mirror according to claim 1, wherein the thin plate portion has an outer diameter in the range of 3 times to 10 times the difference between the inscribed circle dimension and the circumscribed circle dimension of the mirror surface portion. A value obtained by adding a value to the inscribed circle size of the mirror surface. 3. The rotary polygonal mirror according to claim 1, wherein an outer side of the thin plate disk portion outside the polygonal mirror rotating body expands outward, an inclined portion, a stepped enlarged portion, a curved enlarged shape portion, and an arc shape. A rotating polygon mirror characterized by having one of the parts.