JPH05264920A - Rotary polygon mirror - Google Patents

Abstract

PURPOSE:To reduce wind whistle at the time of when the rotary polygon mirror is rotated at a high speed, and to prevent each mirror face from being contaminated. CONSTITUTION:The rotary polygon mirror 1 has the rotary reflecting surface 1A consisting of mirror surfaces 1a-1f being parallel to its rotary shaft, and also, being adjacent to each other, and between each mirror surface 1a-1f, chamfering is performed by a small inclined surface 1O. Each small inclined surface 1O is formed so that an angle made by the mirror surface being toward the front in the rotational direction becomes small by making chamfered width A of the mirror surface being toward the front in the rotational direction of the rotary polygon mirror 1 larger than chamfered width B of the mirror surface being toward the rear thereof, by which air resistance at the time when the rotary polygon mirror 1 is rotated is reduced.

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 of an optical deflection scanning device used in laser printers, laser facsimiles and the like.

[0002]

2. Description of the Related Art An example of an optical deflection scanning device used in a laser printer or a laser facsimile will be described with reference to FIGS. First, in FIG. 3, the light flux generated from the semiconductor laser 2 is collimated by the collimator lens 3 and then linearly condensed by the cylindrical lens 4, and is rotationally reflected by the plurality of mirror surfaces 11 a to 11 f of the rotary polygon mirror 11. The surface 1A is irradiated. The light flux deflected and scanned by each of the mirror surfaces 11a to 11f of the rotary polygon mirror 11 is applied to a reflecting mirror M via an imaging lens system F including a spherical lens 5 and a toric lens 6, and is reflected by the reflecting mirror M to be rotated by the rotating drum D. Reach the upper photoreceptor (shown in FIG. 4). The light flux reaching the photoconductor forms an electrostatic latent image on the photoconductor by the main scanning by the rotation of the rotary polygon mirror 11 and the sub-scanning by the rotation of the rotary drum D.

The drive device for rotating the rotary polygon mirror 11 is
As shown in FIG. 4, a bearing 8 held by a housing 7 has a shaft 9 rotatably supported, and the shaft 9 has a flange 10
Also, the driving magnet 12 is integrally coupled with the driving magnet 12 via the yoke 12a, and the driving magnet 12 is coupled with the driving coil 13 fixed to the housing 7 together with the motor M.
To form. The rotating polygon mirror 11 includes a spring 14 and a stopper plate 1.
5 is pressed against the flange 10, which causes the shaft 9
And is integrally connected to the drive magnet 12 and is rotated by the drive of the motor M ₀ . As shown in FIG. 5A, the mirror surfaces 11a to 11f of the conventional rotary polygon mirror 11 are shown.
Are arranged adjacent to each other around the rotation axis of the rotary polygon mirror 11, and a ridge angle 11γ is formed between the mirror surfaces 11a to 11f.

Recently, along with the increase in speed and precision of the optical deflection scanning device, it is necessary to rotate the rotary polygon mirror 11 at a higher speed.

[0005]

However, in the above-mentioned conventional technique, when the rotary polygon mirror is rotated at a high speed, the air resistance at the ridge angle is remarkably increased and a strong wind noise is generated. There is a problem that the foreign matter X adheres to and contaminates each mirror surface. It is known that, as shown in FIG. 5B, the contamination of the mirror surface is concentrated on each mirror surface, particularly in a region near the front in the rotation direction of the rotary polygon mirror.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art. It is possible to reduce wind noise when rotating at high speed and avoid contamination of each reflecting surface. An object is to provide a rotating polygon mirror.

[0007]

In order to achieve the above object, the rotary polygon mirror of the present invention has a rotary reflecting surface that reflects illumination light, and the rotary reflecting surface is parallel to the rotation axis thereof. And a rotary polygonal mirror composed of a plurality of flat surfaces arranged adjacent to each other around the rotation axis, wherein the ridge angles between the flat surfaces are chamfered, and The chamfer width of the rear end toward the rotation direction of the mirror is
It is characterized in that it is larger than the chamfering width of the end portion on the front side.

[0008]

The small angle formed by each small slope formed by chamfering and the flat surface adjacent to the edge of the small slope adjacent to the front side in the rotation direction causes a small air resistance when the rotary polygon mirror is rotated. Yes.

[0009]

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

FIGS. 1A and 1B show a rotary polygon mirror of one embodiment, FIG. 1A is a plan view thereof, and FIG. 1B is an explanatory view for enlarging and explaining a part including a chamfered portion of FIG. The rotary polygonal mirror 1 of the present embodiment has a hexagonal prism having the rotation axis as the central axis, and all side surfaces of the hexagonal prism as the rotary reflection surface 1A.
A consists of six flat surfaces mirror 1 a - 1 f, which defines the side surface of the hexagonal prism, small slope 1 _O formed by chamfering an edge angle 1γ between each mirror 1 a - 1 f (indicated by a broken line) Is provided. The small inclined surface 1 _O is formed by cutting a mirror surface located forward of the mirror surfaces adjacent to each other in the rotation direction of the rotary polygon mirror 1 more than a mirror surface located behind the mirror surface.

That is, as shown in FIG. 1 (b), a mirror surface 1c located forward of the rotary polygon mirror 1 in the direction of rotation.
Is chamfered so that the chamfered width is A and the chamfered width of the rear mirror surface 1b is B is chamfered so that the relationship of A> B is established.

By such chamfering, air resistance when rotating the rotary polygon mirror is reduced, wind noise is reduced, and in addition, contamination of each mirror surface can be prevented.

FIG. 2 shows the ridge angle 1γ and the rotary reflecting surface 1A.
FIG. 6 is a diagram illustrating the relationship between the ratio of the chamfer widths A and B and the chamfer angle α, where the angle formed by the plane including the rotation axis of 1 and the small slope 1 _O is the chamfer angle α. When the chamfer width B = a, the chamfer width A = a, that is, if A / B = 1, the chamfer angle α is 90 °, and if A / B = 1.5, α =
83 °, A / B = 2, α = 79 ° A / B = 3, α = 74 °, A / B = 4, α = 71 °.

According to the experiment, A / B = 1, that is, α = 9
At 0 °, there is almost no reduction in wind noise and no reduction in pollution. However, if A / B = 1.5 to 4, that is, α is approximately 70 ° to 85 °, wind noise is reduced. Has been found to be significantly reduced and pollution is also reduced. For reference, the conventional rotary polygon mirror and the rotary polygon mirror of the present invention are each rotated at a rotational speed of 15,000 r.p.m. p. Table 1 shows the magnitude of the wind noise and the motor current value when rotated at m. As can be seen from the above, the rotary polygon mirror of the present invention was able to reduce wind noise by 5 dB by reducing air resistance and also reduce the load on the motor by 50 mA.

[0015]

[Table 1]

[0016]

Since the present invention is configured as described above, it has the following effects.

It is possible to reduce wind noise when the rotary polygon mirror is rotated at high speed and prevent contamination of each mirror surface. As a result, it is possible to realize a highly accurate optical deflection scanning device with less noise.

[Brief description of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention,
(B) is a partially enlarged view showing a part of (a) in an enlarged manner.

FIG. 2 is an explanatory diagram illustrating a relationship between a chamfer angle and a chamfer width.

FIG. 3 is an explanatory diagram illustrating an example of an optical deflection scanning device.

FIG. 4 is an explanatory diagram illustrating a driving device of the optical deflection scanning device of FIG.

FIG. 5 is a plan view showing a conventional example,
(B) is an elevation view.

[Explanation of symbols]

1 rotating polygon mirror 1A rotating reflecting surface 1a to 1f mirror surface 1 _O small slope 1γ ridge angle

Claims (2)

[Claims] 1. From a plurality of flat surfaces having a rotary reflecting surface that reflects illumination light, the rotary reflecting surface being parallel to the axis of rotation and arranged adjacent to each other around the axis of rotation. In the rotating polygon mirror, the ridge angles between the flat surfaces are chamfered, and the chamfering width of the end of each flat surface toward the rear in the direction of rotation of the rotary polygon mirror is closer to the front. A polygonal mirror that is larger than the chamfer width of the end of the. 2. An angle formed by a small slope formed by chamfering each ridge angle and a plane including the rotation axis of the ridge angle and the rotary reflecting surface is 70 ° to 85 °. Rotating polygon mirror.