JPH08135651A - Dynamic pressure bearing device - Google Patents

Abstract

PURPOSE: To provide a dynamic pressure bearing device by which sticking and damage to a polygon mirror by abrasion powder can be prevented. CONSTITUTION: In a dynamic pressure bearing device composed of a cylindrical bearing 1 and a rotary shaft 2 having a dynamic pressure generating groove 3, a dust collecting filter 5 which does not hinder an air flow by dynamic pressure is arranged on its end surface side between a polygon mirror 4 supported with the rotary shaft 2 and a thrust directional end surface of a bearing 1. Therefore, since abrasion powder is captured by the dust collecting filter by contact between the shaft and the bearing at starting-stopping time or the like, sticking and damage to the mirror can be beforehand prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a dynamic pressure bearing device suitable for use as a driving device for a polygon mirror used for optical scanning of a laser printer or the like.

[0002]

2. Description of the Related Art Conventionally, the dynamic pressure bearing device shown in FIG. 5 has been widely used as a polygon mirror driving device of a laser printer. In FIG. 5, 1 is a cylindrical bearing, 2 is a rotating shaft,
Reference numeral 3 is a groove for dynamic pressure generation, and 4 is a polygon mirror fixed to a rotary shaft. The above-mentioned dynamic pressure bearing device normally produces a dynamic pressure effect by the dynamic pressure generating groove 3 formed in the rotary shaft 2 when the rotation speed exceeds a certain level, and the rotary shaft 2 and the bearing 1 are operated in a non-contact state. .

[0003]

The polygon mirror used in the laser printer is mirror-finished in order to obtain a high reflectance, and is extremely disliked by dirt and scratches. However, in the hydrodynamic bearing device, abrasion powder generated by sliding at the time of starting and stopping the rotating shaft is entrained and scattered in the gas flow generated by the rotation of the mirror, and adheres to the mirror surface. There is a problem that the mirror surface is damaged and the laser reflectance is lowered. This phenomenon remarkably appears when the rotating shaft and the bearing are coated with a resin that is softer than that using metal plating. As a countermeasure, a method of using a sticky material (for example, Teflon-containing paint) as a coating material to prevent scattering is being studied, but the problem has not been completely solved.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and prevents the flow of air between the dynamic pressure generating portion and the mirror and prevents adhesion and damage to the mirror due to abrasion powder. The main object of the present invention is to provide a dynamic pressure bearing device that can be used.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a hydrodynamic bearing device in which a groove is provided in a rotary shaft or a bearing to generate a dynamic pressure to rotate a rotating body in a non-contact manner to support the rotating body. In the above, the gist is that a dust collecting filter is provided in the flow path of dynamic pressure without obstructing the flow of air due to dynamic pressure.

[0006]

According to the above construction, since the abrasion powder caught in the gas flow and scattered is captured by the dust collecting filter provided in the dynamic pressure passage, it is prevented from adhering to or damaging the mirror surface. To be done.

[0007]

1 and 2 show an embodiment of the present invention. The same or similar members as those in FIG. 5 are designated by the same reference numerals. That is, 1 is a cylindrical bearing, 2 is a rotating shaft,
Reference numeral 3 is a groove for dynamic pressure generation formed on the rotary shaft side, and 4 is a polygon mirror serving as a rotating body.

At the end face of the cylindrical bearing 1 in the thrust direction, a dust collecting filter 5 is provided at a circumferential portion surrounding the rotary shaft 2.
Is provided. As the dust collecting filter 5, a fibrous or porous material that does not interfere with the flow of air and does not affect the dynamic pressure is selected. As described above, the cylindrical bearing 1
According to the configuration in which the dust collecting filter 5 is provided in the dynamic pressure flow path on the end face of the cylinder mouth, the abrasion dust caught in the air flow due to the rotation of the mirror 4 is captured by the dust collecting filter 5, so that the contamination of the mirror or the Damage is prevented in advance.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the mirror 5 is formed with an annular recess 6 on the surface of the cylindrical bearing 1 facing the end face of the cylinder mouth, and the dust collecting filter 5 provided on the end face of the cylinder mouth is configured to enter the recess 6. . Also in the above embodiment, the same dust collecting effect as described above can be obtained. Further, according to the configuration of the present embodiment, it becomes possible to more reliably allow the air to pass through the dust collecting filter with respect to the mirror that is vertically displaced by rotation.

FIG. 4 shows another embodiment of the present invention. In the present embodiment, the dust collecting filter 5 is provided on the inner surface of the cylindrical opening of the cylindrical bearing 1, and the dust collecting filter 5 is configured to enter the recess 7 provided on the peripheral surface of the rotating shaft 2. Also in this embodiment, the same dust collecting effect as described above can be obtained, and more reliable air can be passed through the dust collecting filter with respect to the mirror which is vertically displaced by rotation.

The above-mentioned various embodiments show the construction in which one dust collecting filter is installed, but the dust collecting filters may be installed in double or triple layers. Also,
The dust collecting filter may be installed on the mirror side.

[0012]

As described above in detail, according to the structure of the dynamic pressure bearing device of the present invention, when the polygon mirror for a laser printer is used as a drive device, contamination or damage of the mirror due to abrasion powder is prevented. , Can maintain high reflectance for a long time. Further, when the lubricating shaft is coated on the rotary shaft and the bearing of the dynamic pressure bearing device, the degree of freedom of the coating material is increased, and a hard material having higher wear resistance can be selected. Generally, a viscous material is easily worn and a large amount of Teflon increases the cost, but this point can be eliminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a dynamic pressure bearing device showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the device.

FIG. 3 is a sectional view of a main part of a dynamic pressure bearing device showing another embodiment of the present invention.

FIG. 4 is a sectional view of an essential part of a dynamic pressure bearing device showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional dynamic pressure bearing device.

[Explanation of symbols]

 1 Cylindrical bearing 2 Rotating shaft 3 Dynamic pressure generating groove 4 Polygon mirror 5 Dust collection filter 6 Mirror side recess 7 Rotating shaft side recess

Claims (4)

[Claims] 1. A dynamic pressure bearing device for supporting a rotating body by rotating a rotating body in a non-contact manner by providing a groove on a rotary shaft or a bearing to generate a dynamic pressure, and a dust collecting filter which does not obstruct the flow of air due to the dynamic pressure. A dynamic pressure bearing device provided in a flow path of discharged air. 2. The dynamic pressure bearing according to claim 1, wherein the rotating body is a polygon mirror, and a dust collecting filter is provided between the polygon mirror and an end face in a thrust direction of a bearing formed so as to surround the polygon mirror. apparatus. 3. The hydrodynamic bearing device according to claim 1, wherein a dust collecting filter is provided on an end surface of the bearing in the thrust direction. 4. The hydrodynamic bearing device according to claim 1, wherein the rotating body is a polygon mirror, and a dust collecting filter is provided on the polygon mirror.