JPH116975A - Bearing device and deflecting scanner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the vibration of a rotor part and to reduced the cost by oppositely providing 1st and 2nd permanent magnets in a circumferential direction perpendicular to a shaft direction and making the 1st permanent magnet have shape to cover over the 2nd permanent magnet attached to the end of a shaft. SOLUTION: The 1st annular permanent magnet 2 is attached to the upper end of a rotary sleeve 24, and the 2nd cylindrical permanent magnet 1 is attached to the upper end of the fixed shaft 22 at a position where it is opposed to the inner peripheral surface of the magnet 2 in the circumferential direction perpendicular to the axial direction. The magnets 2 and 1 are constituted so that magnetic poles may be different on their inner and outer peripheral surfaces. The magnet 2 has the shape to cover over the upper part of the magnet 1. When the sleeve 24 is rotated, it is supported in a thrust direction by magnetic force acting between the magneto 2 and 1, air in an air reservoir 31 sealed by the magnet 2 attenuates the vertical motion of the sleeve 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device in which a sleeve is fitted to a shaft and supported so as to be relatively rotatable, and a deflection scanning device using the same.

[0002]

2. Description of the Related Art Conventionally, in order to improve the accuracy of this type of deflection scanning device, a bearing device capable of rotating at high speed and with high accuracy is required. A pressure fluid bearing is used.

FIG. 5 is a sectional view of a deflection scanning device using a bearing device using a hydrodynamic bearing disclosed in Japanese Patent Application Laid-Open No. 8-5951. A fixed shaft 22 made of a ceramic material is fixed to a housing 21 of the drive motor.
2, a rotating sleeve 24 made of a ceramic material is rotatably fitted. A flange 25 made of aluminum or brass is fixed to the outer periphery of the rotating sleeve 24 by shrink fitting or the like, and a drive magnet 26 is fixed to the outer periphery of the flange 25 by bonding or the like. Further, a drive motor is configured by disposing a stator 28 on a substrate 27 fixed on the housing 21 so as to face the drive magnet 26.

On the other hand, a second permanent magnet 30 is attached to the upper end of the fixed shaft 22.
The first permanent magnet 29 is fixed to the rotating sleeve 24 so that different types of magnetic poles face each other in the vertical direction (axial direction of the fixed shaft).

[0005] As a result, the rotating sleeve 24 is levitated by the magnetic repulsive force, and an air pocket 31 is generated between the fixed shaft 22 and the first permanent magnet 29. Also,
The first permanent magnet 29 is provided with a through hole 23a for communicating the air reservoir 31 with the outside.
2 is detachably attached. Further, a rotating polygon mirror 34 is fixed on the flange 25 by a leaf spring 33 fixed to the rotating sleeve 24.

With such a configuration, when the fixed shaft 22 and the rotary sleeve 24 are fitted together with the plug 32 removed, the air in the rotary sleeve 24 passes through the through hole 2.
3a, and can be easily fitted. When the rotating sleeve 24 rotates, the rotating sleeve 24 is radially supported by an air film between the rotating sleeve 24 and the fixed shaft 22, and a magnetic force (repulsive force) acting between the permanent magnets 29 and 30. Is supported in the thrust direction. At this time, the air in the air reservoir 31 sealed by the plug 32 acts to attenuate the vertical movement of the rotating sleeve 24, and holds the rotating sleeve 24 at a stable floating position.

[0007]

As described above, in this conventional example, two permanent magnets for floating the thrust are provided so as to oppose each other in the axial direction of the fixed shaft.

In such a configuration, the rotating sleeve 24 vibrates very unstable in the vertical direction (axial direction) in response to disturbance such as vibration to the apparatus. Although the up-and-down vibration is reduced to some extent by the air reservoir 31, it is not sufficient by itself.

Such vibration of the rotary sleeve causes the rotary polygon mirror attached to the rotary sleeve to move up and down, which hinders good deflection scanning.

Further, in order to arrange the permanent magnet 29 above the permanent magnet 30, it is necessary to extend the rotary sleeve 24 made of an expensive ceramic material to the upper side.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to improve the arrangement of permanent magnets for floating the thrust, thereby preventing the vibration of the rotor portion (rotary sleeve or rotary shaft) and reducing the cost. It is an object of the present invention to provide a bearing device which can be used and a deflection scanning device using the same.

[0012]

In order to achieve the above-mentioned object, a bearing device according to the present invention has a sleeve which is relatively rotatably fitted around a shaft, and one of the shaft and the sleeve is attached to the sleeve. A first permanent magnet is attached to the rotor portion, a second permanent magnet is attached to a position facing the first permanent magnet, and the first permanent magnet and the second permanent magnet are attached to the rotor portion. In the bearing device in which the rotor part floats with respect to the stator part by a magnetic force acting between the permanent magnets, the first permanent magnet and the second permanent magnet are arranged in a circumferential direction perpendicular to the axial direction. And the first permanent magnet or the second permanent magnet covers the second permanent magnet or the first permanent magnet attached to the end of the shaft. It is characterized by having a shape.

Further, a deflection scanning device according to the present invention is a deflection scanning device having a deflector for deflecting and scanning a light beam, and a rotating device for rotating and driving the deflector, wherein a bearing of the rotating device is provided around a shaft. , A sleeve is relatively rotatably fitted to the shaft, and one of the shaft or the sleeve is a stator portion and the other is a rotor portion. A first permanent magnet is attached to the rotor portion and faces the first permanent magnet. A second permanent magnet is mounted at a position where the rotor unit is to float with respect to the stator unit by a magnetic force acting between the first permanent magnet and the second permanent magnet. The first permanent magnet and the second permanent magnet are provided so as to face each other in a circumferential direction perpendicular to the axial direction, and the first permanent magnet or the second permanent magnet is provided at an end of the shaft. Said second permanent attached to Characterized in that a shape to cover the stones or the first permanent magnet.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS.

FIG. 1 is a sectional view of a first embodiment of a deflection scanning apparatus using a bearing device using a hydrodynamic bearing.

In FIG. 1, a housing 2 of a drive motor is provided.
A fixed shaft 22 (part of the stator portion) made of a ceramic material is fixed to 1, and a rotating sleeve 24 (part of the rotor portion) made of a ceramic material is rotatably fitted to the fixed shaft 22. A flange 25 made of aluminum or brass is fixed to the outer periphery of the rotating sleeve 24 by shrink fitting or the like, and a drive magnet 26 is fixed to the outer periphery of the flange 25 by adhesion or the like. Furthermore, a drive motor is configured by disposing a stator 28 including a coil and a core on a substrate 27 fixed on the housing 21 so as to face the drive magnet 26.

On the other hand, an annular first permanent magnet 2 is attached to the upper end of the rotary sleeve 24,
The cylindrical second permanent magnet 1 is attached to the upper end of the fixed shaft 22 at a position opposed to the inner peripheral surface of the permanent magnet 2 in the circumferential direction (radial direction of the shaft) perpendicular to the axial direction. . First
The inner peripheral surface of the permanent magnet 2 and the outer peripheral surface of the second permanent magnet 1 are in a circumferential direction perpendicular to the axial direction of the fixed shaft (radial direction of the shaft).
The magnetic poles facing each other are configured to be different types of magnetic poles. The arrangement of the magnetic poles is not limited to this.

The ring-shaped first permanent magnet 2 is made of plastic and has a shape covering the upper part of the second permanent magnet 1 attached to the upper end of the fixed shaft 22. That is, the first permanent magnet 2 made of plastic has a ring-shaped portion and a lid-shaped portion which are magnetized so as to integrally have a magnet function of thrust support. As described above, in order to integrally form the ring-shaped portion and the lid-shaped portion,
A plastic permanent magnet formed by injection molding a magnetic material mixed with a resin is preferable.

As a result, the rotating sleeve 24 is levitated with respect to the fixed shaft 22 by magnetic force,
An air pocket 31 (air damper chamber) is formed between the second permanent magnet 1 and the first permanent magnet 2. Further, a rotating polygon mirror 34 is fixed on the flange 25 by a leaf spring 33 fixed to the rotating sleeve 24.

When the rotating sleeve 24 rotates, the rotating sleeve 24 is fixed to the rotating shaft 24 and the fixed shaft 22.
Between the first permanent magnet 2 and the second permanent magnet 1 in the thrust direction. At this time, the first permanent magnet 2
The air in the air reservoir 31 sealed by the rotary sleeve 2 acts to attenuate the vertical movement of the rotary sleeve 24, and the rotary sleeve 2
4 can be held in a stable floating position.

As described above, the first permanent magnet attached to the rotor portion and the second permanent magnet attached to the stator portion face each other in the circumferential direction perpendicular to the axial direction (radial direction of the shaft). By providing the support, the permanent magnets for floating the thrust are supported so as to face each other, so that the positional restraining force in the thrust direction is far greater than the vertical (axial) repulsion support shown in FIG. And the vertical swing of the rotating sleeve, which is the rotor, is extremely small with respect to disturbances such as vibration of the apparatus. Therefore, the vertical movement of the rotary polygon mirror attached to the rotary sleeve can be suppressed to a small level.

Further, since the size in the height direction (axial direction) can be reduced as compared with the configuration of the rebound support in the vertical direction (axial direction) shown in FIG. 5, the apparatus can be downsized. .

Further, since a cover member for covering the upper portion of the permanent magnet attached to the upper end of the fixed shaft is integrally formed by using a plastic permanent magnet, the number of assembly steps is reduced and the number of parts is reduced. Can be reduced, resulting in cost reduction.

FIG. 2 shows a second embodiment. In the second embodiment, the first permanent magnet 2 is provided with a through hole 23a for communicating the air reservoir 31 with the outside.
The plug 32 is detachably attached to a. 1 denote the same members, and a description thereof will be omitted.

In the second embodiment, in addition to the effects of the first embodiment, when the fixed shaft 22 and the rotating sleeve 24 are fitted together with the plug 32 removed, the inside of the rotating sleeve 24 is removed. The air flows away from the through hole 23a and can be easily fitted.

FIG. 3 shows a third embodiment. The third embodiment is an embodiment of a deflection scanning device using a bearing device using a shaft rotating type hydrodynamic bearing, in which a rotating shaft 3 made of a ceramic material and a fixed sleeve made of a ceramic material are used. 4 is used. A groove for attaching the leaf spring 33 is provided on the upper part of the rotating shaft 3.

An annular second permanent magnet 5 is attached to the lower end of the fixed sleeve 4 as a stator,
The first cylindrical magnet is provided at a position facing the inner peripheral surface of the second permanent magnet 5 in a circumferential direction (radial direction of the shaft) perpendicular to the axial direction.
Are attached to the lower end of the rotating shaft 3. As for the inner peripheral surface of the second permanent magnet 5 and the outer peripheral surface of the first permanent magnet 6, magnetic poles facing each other in a circumferential direction (radial direction of the axis) perpendicular to the axial direction of the rotating shaft are different types of magnetic poles. It is configured as follows.

Here, the annular second permanent magnet 5 is made of plastic and has a shape covering the lower part of the first permanent magnet 6 attached to the lower end of the rotating shaft 3. That is, the second permanent magnet 5 made of plastic has a ring-shaped portion and a lid-shaped portion which are magnetized so as to integrally have a magnet function of thrust support. As described above, in order to integrally form the ring-shaped portion and the lid-shaped portion,
A plastic permanent magnet formed by injection molding a magnetic material mixed with a resin is preferable. Further, a through hole 23a for communicating the air reservoir 31 with the outside is provided in the second permanent magnet 5, and a plug 32 is detachably attached to the through hole 23a. In addition, the same code | symbol as FIG. 2 shows the same member,
Description is omitted.

In the third embodiment, in addition to the effects of the second embodiment, since the shaft is of a type in which the shaft rotates, a cylindrical magnet having small inertia can be arranged on the rotating body side (the rotor section side). This has the effect of reducing the inertia of the rotating body.

FIG. 4 is a block diagram of a deflection scanning apparatus using the bearing device of the above-described embodiment. A laser unit 36 is mounted on an optical box 35, and a rotating path is provided on an optical path L emitted from the laser unit 36. Polygon mirror 34 and lens 3
Reference numerals 7 and 38 are disposed inside the optical box 35, and a photosensitive member 39 as a recording medium is disposed outside the optical box 35.

The laser light emitted from the laser unit 36 is deflected and scanned by a rotating polygon mirror 34 supported and rotated by a bearing device, and is spotted on a photosensitive member 39 outside the optical box 35 via lenses 37 and 38. It is projected as light and main scanning is performed.

A corona discharge device for uniformly charging the surface of the photoconductor 39 is provided around the photoconductor 39, and an electrostatic latent image formed on the surface of the photoconductor 39 is visualized as a toner image. And a transfer unit for transferring the toner image onto a recording sheet, etc., and recording information by a laser beam generated from the laser unit 36 is printed on the recording sheet or the like.

By using the bearing device of this embodiment, vertical movement of the rotary polygon mirror caused by disturbances such as vibration of the device is suppressed, and high-speed and high-precision deflection scanning can be stably performed, and the cost can be reduced. A deflection scanning device can be provided.

[0034]

As described above, in the bearing device according to the present invention and the deflection scanning device using the same, the rotor for thrust levitation is arranged so as to face the circumferential direction perpendicular to the axial direction. Providing at each end of the rotor section and the stator section can prevent the vibration of the rotor section (rotating sleeve or rotating shaft), enable high-speed, high-precision rotation support, deflection scanning, and the thrust floating Since the air damper chamber is also configured using permanent magnets, costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a bearing device of the present invention.

FIG. 2 is a view showing a configuration of a second embodiment of the bearing device of the present invention.

FIG. 3 is a view showing a configuration of a third embodiment of the bearing device of the present invention.

FIG. 4 is a diagram illustrating a configuration of a deflection scanning device.

FIG. 5 is a diagram showing a configuration of a conventional bearing device.

[Explanation of symbols]

 Reference Signs List 1 permanent magnet 2 permanent magnet 22 fixed shaft 24 rotating sleeve 34 rotating polygon mirror

Continued on the front page (72) Inventor Taku Fukuroda Canon Inc., 3-30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Kazumi Sato Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Akihiro Fukutomi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (6)

[Claims] 1. A sleeve is relatively rotatably fitted around a shaft, one of the shaft or the sleeve is a stator portion, the other is a rotor portion, and a first permanent magnet is attached to the rotor portion. A second permanent magnet is mounted at a position facing the first permanent magnet, and the rotor unit is moved relative to the stator unit by a magnetic force acting between the first permanent magnet and the second permanent magnet. In the bearing device to be levitated, the first permanent magnet and the second permanent magnet are provided to face each other in a circumferential direction perpendicular to an axial direction, and the first permanent magnet or the second permanent magnet is provided. A bearing device, wherein the magnet is shaped so as to cover the second permanent magnet or the first permanent magnet attached to the end of the shaft. 2. The bearing device according to claim 1, wherein the first permanent magnet or the second permanent magnet is a plastic permanent magnet. 3. The bearing device according to claim 1, wherein the shaft and the sleeve are formed of a ceramic material. 4. A deflection scanning device having a deflector for deflecting and scanning a light beam and a rotating device for rotating and driving the deflector, wherein a bearing of the rotating device makes a sleeve relatively rotatable around an axis. The shaft or the sleeve is fitted with one of the stator and the other as the rotor.
Is attached, and a second permanent magnet is attached at a position facing the first permanent magnet. The magnetic force acting between the first permanent magnet and the second permanent magnet causes the rotor unit to be mounted. The first permanent magnet and the second permanent magnet are provided so as to face each other in a circumferential direction perpendicular to an axial direction, and the first permanent magnet is provided. Alternatively, the second permanent magnet is shaped to cover the second permanent magnet or the first permanent magnet attached to an end of the shaft. 5. The deflection scanning device according to claim 4, wherein the first permanent magnet or the second permanent magnet is a plastic permanent magnet. 6. The deflection scanning device according to claim 4, wherein the shaft and the sleeve are formed of a ceramic material.