JPH1164772A - Bearing for scanner motor of polygon mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing for scanner motor of polygon mirror by which torque fluctuation is restrained, torque is made low and the shortage of lubricant is hardly caused and whose life is prolonged. SOLUTION: An annular space 4 formed by the outer ring 1 and the inner ring 2 of the bearing for the scanner motor of the polygon mirror and hermetically sealing plates 6 and 7 arranged on both sides between the rings 1 and 2 is filled with the mixture of thermoplastic resin and a lubricating oil component so as to form a heated and solidified lubricant composition 8. Since a lubricant component is gradually oozed out from the solidifed composition 8 by centrifugal force and heat at the time of using a rolling bearing and lubricity is achieved, the torque fluctuation caused by a diffused resistor like grease lubrication is eliminated, and the life of the bearing is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning polygon mirror (polygon mirror) for a laser printer or the like.
More particularly, the present invention relates to a polygon mirror scanner motor bearing for preventing contamination by a lubricant.

[0002]

2. Description of the Related Art A rotating mechanism of a light scanning polygon mirror of a laser scanning optical system of a laser printer or the like changes an incident angle of a light beam projected from a light source in accordance with rotation of the polygon mirror. This is a mechanism for changing and deflecting in a desired direction. The rotating mechanism is configured to rotate a polygon mirror for light beam reflection, which is finished with high precision by ultra-precision machining, at high speed. For each surface of the polygon mirror, surface tilt angle accuracy, division angle accuracy, surface accuracy, reflectivity, etc. are strictly determined. Laser power laser
The spot shape and the like are affected.

FIG. 5 shows a configuration example of a conventional rotating mechanism of an optical scanning polygon mirror. As shown in FIG. 5, a stator 22 constituting a rotating motor is disposed below a bearing housing 20. A rotor 21 is disposed at a position facing the stator 22, and the rotor 21 is mounted on a rotating shaft 23 supported by bearings 24 and 25 at the center of the housing 20. A fixed base 26 is attached to the upper part of the rotating shaft 23, and a polygon mirror (polyhedral mirror) 28 having 8 to 10 faces is installed on the fixed base 26. The polygon mirror 28 is fixed to the rotating shaft 23 with a nut 30 via a rubber ring 27 and a holding plate 29, and its outer periphery is covered with a cover 31 having a laser scanning window 31a. . The bearings 24 and 25 are, in particular, polygon mirrors.
28 is a bearing having a contamination prevention structure so as not to contaminate the surface.

As a measure to prevent contamination of the surroundings by a bearing, a lubricating composition formed by solidifying a mixture of a thermoplastic resin such as polyethylene and a lubricating oil component has been proposed (Japanese Patent Application Laid-Open No. 54-22415). , Tokubo 63-23239
And Japanese Patent Publication No. 3-67559). Such a solidified lubricating composition, in a state where a cage and a rolling element are arranged in an annular space between an outer ring and an inner ring of a rolling bearing,
After filling in a fluid state, the mixed composition is obtained by heating the mixture to a temperature equal to or higher than the melting point of the resin and then cooling the mixture. The solidified lubricating composition exhibits lubricity as a result of the lubricating component gradually oozing out due to centrifugal force and heat during use of the rolling bearing. Therefore, there is no risk that the lubricating component will be scattered when the rolling bearing rotates, and it is not necessary to reinforce the lubricating component over a long period of time.

[0005]

As described above, the bearings 24 and 25 of the rotating mechanism of the polygon mirror for optical scanning have a complicated seal structure so as not to contaminate the polygon mirror 28. However, the bearings 24 and 25 are usually grease lubricated, and their viscosity changes depending on the temperature and the like, so that there is a problem that torque fluctuation is large, and it is difficult to supply the lubricant, so that the life is short. Further, there is a problem that the polygon mirror 28 is easily contaminated by the grease of the lubricant due to the structure of the bearing arrangement.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and a polygon mirror scanner bearing for a scanner motor which has a small torque fluctuation and a low torque, is less likely to run out of lubricant, and has a long life. It is intended to provide.

[0007]

In order to solve the above-mentioned problems, the present invention has a stator arranged in a housing, a rotor arranged and fixed at a position facing the stator, and a polygon. In a bearing for a scanner motor of a polygon mirror for supporting a rotating shaft on which a mirror is mounted, the bearing is formed by an outer ring of the bearing, an inner ring, and sealing plates disposed on both sides between the outer and inner rings. An annular space is filled with a mixture of a thermoplastic resin and a lubricating oil component, and a heated and solidified lubricating composition is formed.

The thermoplastic resin is 20 to 40% by weight, and the lubricating oil component is 80 to 60% by weight.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial sectional view of a bearing for a scanner motor of a polygon mirror according to the present invention. The bearing includes an outer ring 1, an inner ring 2, a rolling element (ball) 3 disposed in an annular space 4 between the outer ring 1 and the inner ring 2, and a retainer 5 for retaining the rolling element 3. When,
The annular space 4 is disposed at both ends between the outer ring 1 and the inner ring 2.
Sealing plates 6 and 7 for sealing the
And the solidified lubricating composition 8 filled in the annular space 4 surrounded by

[0010] The lubricating composition 8 comprises a thermoplastic resin,
It is a mixture with the lubricating oil component and is filled in the annular space 4. The procedure for solidification will be described later. As shown in FIG. 1 and FIG. 2A which is a partially enlarged view of FIG.
A film 9 of a lubricating oil component is formed on the surfaces of the outer ring 1, the inner ring 2 and the cage 5. The film 9 is formed before filling the lubricating composition 8 between the outer ring 1 and the inner ring 2,
As described later, the lubricating composition 8 is prevented from sticking to the surfaces of the outer ring 1, the inner ring 2, the retainer 5, and the like in the process of forming the lubricating composition 8, and seizure occurs due to lack of lubrication at the start of rotation. It is formed in order to prevent the occurrence. As the lubricating component, an oil component (a synthetic oil such as poly-α-olefin, diester, perfluoropolyether, or a mineral oil) of a lubricating composition mixed with a thermoplastic resin described later may be used. However, since the lubricating oil component film 9 oozes out of the lubricating composition 8, it is not always necessary to form the lubricating oil component film 9 as shown in FIG. 2 (B).

The sealing plate 6 (the sealing plate 7 has the same configuration)
Is made by baking rubber 6b on a cored bar 6a,
1 is press-fitted and fixed to grooves 1a, 1b provided at both ends of the outer ring 1, and the inner peripheral portion 62 is a chamfered portion 2a, 2b at both ends of the inner ring 2.
2b is elastically contacted. The sealing plates 6 and 7 are replaced by metal sealing plates 16 and 17 (FIG.
See also).

Next, a scanner model of the polygon mirror is used.
A method of manufacturing a bearing for a motor will be described with reference to FIG. First, a cage assembly in which a rolling element (ball) 3 is held by a cage 5 is incorporated in an annular space 4 between the outer ring 1 and the inner ring 2. Then, as shown in FIG. 3A, the assembly of the outer ring 1, the inner ring 2, and the retainer assembly is immersed in an oil tank 11 containing the lubricating oil 10. Thus, the lubricating oil component film 9 (see FIGS. 1 and 2A) is formed on the surfaces of the outer ring 1, the inner ring 2, the ball 3, and the retainer 5. still,
When forming the film 9 of the lubricating oil component, a sprayer or the like may be used.

Next, as shown in FIG. 3 (B), a sealing plate 6 is fitted into one end between the outer ring 1 and the inner ring 2 so that the sealing plate 6 is on the lower side, and The fluid lubricating composition is filled. Then, the other sealing plate 7 is fitted on the upper side, and the annular space 4 is filled with the lubricating composition to make a sealed state. Next, the fluid mixture is heated to a temperature equal to or higher than the melting point of the thermoplastic resin and then cooled, whereby the solidified lubricating composition 8 is obtained. In the process shown in FIGS. 3B and 3C, the annular space 4 between the outer ring 1 and the inner ring 2
The sealing is carried out by the sealing plate 7, but is not limited to the sealing plates 6 and 7, and any other member such as an annular sealing jig can be used as long as one of the annular spaces 4 is covered and the fluid mixture can be sealed. May be used.

As described above, in the method of forming the lubricating composition 8 to be filled and solidified in the annular space 4 between the outer ring 1 and the inner ring 2, the raw material of the fluid lubricating composition 8 is a thermoplastic resin and a thermoplastic resin. It is a lubricating oil component. Examples of such a thermoplastic resin include ultrahigh molecular weight polyethylene, polypropylene, polymethylpentene, and polyurethane. Then, the thermoplastic resin is supplied as a granular material. As the lubricating oil component, a synthetic oil or a mineral oil such as poly-α-olefin, diester, perfluoropolyether or the like is used. The powdery thermoplastic resin is mixed with these fluid lubricating oils at a predetermined ratio. The lubricating oil component has a kinematic viscosity of about 8 to 30 mm ² / S (stokes) at 40 ° C. The reason is that if the value is less than the above value, it is not possible to form the lubricating component film 9 having a sufficient thickness, and if the value is more than the above range, the viscosity of the lubricating component is too high. In any case, the effect of reducing the friction with the solidified lubricating composition 8 becomes insufficient,
This is because the rotational torque of the rolling bearing may increase.

The combination of the lubricating composition may be a mixture of ultra-high-molecular-weight polyethylene and poly-α-olefin, a mixture of ultra-high-molecular-weight polyethylene and diester, or a mixture of polypropylene and poly-α-olefin. And each lubricating oil component can be arbitrarily combined and mixed. The heating temperature is, for example, 160 ° C. for a lubricating composition containing 10 to 90% by weight of ultra high molecular weight polyethylene having a melting point of 136 ° C. (therefore, lubricating oil is 90 to 10% by weight).
It can be solidified by heating at a temperature of about 170 ° C. for about 5 minutes to several tens of minutes (preferably about 5 minutes to 15 minutes), followed by cooling. In this way, a solidified lubricating composition can be formed by heating for a predetermined period of time at a temperature slightly higher than each of the thermoplastic resins according to the melting point of the thermoplastic resin and then cooling.

As described above, in the embodiment of the solidified lubricating composition 8, the components of the thermoplastic resin
The reason for setting the lubricating oil composition to 90% by weight and the lubricating oil composition to 90 to 10% by weight is as follows. That is, if the thermoplastic resin is 10% by weight or less, it does not solidify, and if the lubricating oil composition is 10 or less, the lubricating oil component does not sufficiently ooze out when solidified, resulting in poor lubricity. . The mixing ratio of the thermoplastic resin and the lubricating oil component is preferably such that the thermoplastic resin is 20 to 4 parts.
0% by weight, and the lubricating oil component is preferably 80 to 60% by weight.

FIG. 4 shows an embodiment of a modification of the present invention. The annular space 4 between the outer ring 1 and the inner ring 2 is sealed with metal seal plates 16 and 17, and the outer ring 1 and the inner ring 2 are sealed. This is an example in which a solidified lubricating composition 8 is filled in this annular space 4 sealed with metal seals 16 and 17. In this case, the film 9 of the lubricating oil component may or may not be formed. If the film 9 is not formed, the lubricating oil component oozes out of the solidified lubricating composition 8, and thus there is no lubrication problem.

[0018]

As described above in detail, according to the polygon mirror scanner motor bearing of the present invention, since grease or the like is not used as a lubricant, there is no resistance to sales expansion during rotation, and torque fluctuation is reduced. Disappears. Further, between the rolling element and the raceway surface, the lubricating oil component in the solidified lubricating composition filled between the outer ring and the inner ring is leached out and lubricated, and the lubricating oil component in these lubricating compositions is Since it is sufficiently present, seizure hardly occurs and the life of the bearing can be prolonged. Furthermore, since the polygon mirror scanner motor bearing is not grease lubricated, it does not contaminate the periphery of the polygon mirror and the like.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a polygon mirror scanner motor bearing according to the present invention.

FIG. 2A is a partially enlarged view of FIG. 1, and FIG.
(B) is a diagram showing an embodiment in which a solidified lubricating composition is formed in an annular space surrounded by an outer ring, an inner ring, and a sealing plate without forming a film of a lubricating oil component.

FIG. 3A is a partial cross-sectional view of a bearing showing an operation of forming a film of a lubricating component on the surfaces of an outer ring, an inner ring, a ball and a cage, and FIG. FIG. 3C is a partial cross-sectional view of a bearing showing an operation of filling a fluid lubricating composition into an annular space between an outer ring and an inner ring, and FIG. 3C is surrounded by sealing plates on both sides of the outer ring and the inner ring; FIG. 4 is a partial cross-sectional view of a bearing in which a lubricating composition is filled and fixed in a closed annular space.

FIG. 4 shows an embodiment of a modification of the present invention, in which both sides of an annular space between an outer ring and an inner ring are sealed with metal seal plates, and the annular space is filled with a solidified lubricating composition. This is an example in the case of having been performed.

FIG. 5 is a cross-sectional view showing an example of the structure of a rotating mechanism of an optical scanning polygon mirror of a laser scanning optical system of a conventional laser printer or the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer ring 2 Inner ring 3 Rolling element 4 Annular space 5 Cage 6,7 Sealing plate 8 Lubricating composition 9 Film of lubricating oil component

Claims (2)

[Claims] 1. A polygon mirror for arranging a stator in a housing, locating and fixing a rotor at a position facing the stator, and supporting a rotary shaft on which a polygon mirror is mounted.
A mixture of a thermoplastic resin and a lubricating oil component in an annular space formed by an outer ring of the bearing, an inner ring, and sealing plates disposed on both sides between the outer and inner rings. And a heated and solidified lubricating composition formed from the above. 2. The polygon mirror scanner motor bearing according to claim 1, wherein the thermoplastic resin is 20 to 40% by weight and the lubricating oil component is 80 to 60% by weight.