JP2000205257A - Rotating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotating device having a wide adjusting range, excellent in productivity and having stable performance at a high-speed rotation by providing a ring-shaped magnetic body on a rotary unit, and providing a permanent magnet generating attracting force in one direction at a position on a base or a housing facing the magnetic body. SOLUTION: A ring-shaped magnetic body 51 having magnetism such as iron is provided on a rotary unit 2, single or multiple permanent magnets 52 are provided on a fixed support base plate 3 or a housing 50 fixed to cover the side face of a rotating device, and the rotary unit 2 is pulled in the radial direction by the fixed attracting force generated between the magnetic body 51 and the permanent magnets 52. The attracting force is determined by the magnetic force of the permanent magnets 52 and the distance D between the permanent magnets 52 and the magnetic body 51. No rotation instability occurs even in the region with a small dynamic balance, the correction region of a dynamic balance adjustment and the gap adjustment tolerance in the radial direction of a radial dynamic pressure bearing section are expanded, and a production margin is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating device that rotates at a high speed, such as a light deflecting device or a motor using a polygon mirror.

[0002]

2. Description of the Related Art In a light deflecting device that rotates at high speed around a polygon mirror as a rotating body or a motor that rotates at high speed around a rotating shaft, a dynamic pressure bearing is provided between a rotating body and a non-rotating body.
High speed rotation is performed. FIG. 6 is a sectional view showing an example of a rotating device provided with a dynamic pressure bearing. The rotating units rotating opposite to the radial fixing member fixed on the support base perform radial dynamic pressure rotation between them in the radial dynamic pressure bearing portion. At both ends of the radial fixing member, there are provided thrust fixing members which are perpendicular to the axis of the radial fixing member, and the thrust fixing members located above and below are rotated between the thrust fixing members. The unit performs thrust dynamic pressure rotation in a thrust dynamic pressure bearing portion.

The radial dynamic pressure bearing portion and / or the thrust dynamic pressure bearing portion have a dynamic pressure generating groove formed symmetrically on the bearing surface, and wind generated by high-speed rotation of the rotating unit is introduced into the dynamic pressure generating groove. A strong wind pressure is generated from the symmetrically formed dynamic pressure generating groove, and a gap of several μm is formed between the radial fixing member and the rotating unit, thereby reducing the resistance between the two, The high-speed rotation is performed in the radial dynamic pressure bearing portion. Also, a minute gap is formed between the thrust fixing member and the rotating unit, so that the rotating unit rotates at a high speed in the thrust dynamic pressure bearing portion while slightly floating.

[0004]

In a conventional rotating device in which a symmetrical dynamic pressure generating groove is provided in a dynamic pressure bearing portion, contact is prevented in order to prevent contact generated during high-speed rotation of the rotating unit and reduce vibration. Generally, the balance is reduced. However, if the dynamic balance is too small, the unstable rotation may occur. In the conventional rotating device, the upper limit of the dynamic balance is specified by the allowable limit of vibration and the lower limit is specified by the allowable limit of stability, and the dynamic balance is corrected so as to be within the range between the specified upper limit and lower limit. Alternatively, the stability in high-speed rotation has been obtained by optimizing the gap between the fixed portion (radial fixing member) and the rotating body (rotating unit) in the radial dynamic pressure bearing portion.

An object of the present invention is to provide a rotating device which does not cause rotational instability even in a region where the dynamic balance is small, has a wide adjustment range, is excellent in productivity, and has stable rotating performance at high speed. With the goal.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a rotating device in which a rotating unit having an outer cylinder bearing has a dynamic pressure bearing which rotates between an inner cylinder bearing fixed to a base or a housing. 2. A rotating device according to claim 1, wherein the unit is provided with a ring-shaped magnetic body, and the base or the housing is provided with a permanent magnet that generates an attraction force in one direction at a position facing the magnetic body. Invention) and a rotating device having a dynamic pressure bearing that rotates between a rotating unit having an outer cylinder bearing and an inner cylinder bearing fixed on a base, wherein the rotating unit is provided with a permanent magnet for generating torque. A rotating device (invention of claim 2) and a rotating unit having an outer cylinder bearing, wherein a plurality of magnet coils provided in a ring shape are arranged eccentrically with respect to the inner cylinder bearing on the base. The rotary device having a dynamic pressure bearing which rotates with the cylindrical bearing inner fixed in the housing,
This is achieved by a rotating device (invention of claim 3), wherein a narrow portion for generating air pressure is provided at a distance between an outer peripheral surface of the rotating unit and an inner surface of the housing.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a preferred embodiment of a rotating device according to the present invention, a description will be given using an optical deflecting device which rotates at high speed by fixing a polygon mirror to a rotating unit. FIG. 1 shows a cross-sectional configuration of the rotating device. Fixed radial shaft 11
A cylindrical inner bearing 12 made of a ceramic material, a stainless steel material, or the like, having a cylindrical shape is fixed to the outside of the radial shaft 11.
And the inner cylinder bearing 12 constitute a radial fixing member.
An upper thrust bearing 13A and a lower thrust bearing 13B made of a ceramic material or a stainless material having a disk shape in a direction substantially perpendicular to the radial axis are fixed to both end portions of the inner cylindrical bearing 12, and each is fixed by thrust. It constitutes a member. The radial fixing member and the thrust fixing member integrally constitute a main body fixing portion of the rotating device, and are fixed to the support base plate 3.

On the other hand, a rotary unit 2 which is a unit for rotating the rotary device at high speed is provided with a cylindrical outer cylinder bearing 21 having a rotation axis as a center.
The outer diameter of the fixed inner cylindrical bearing 12 is larger than the inner diameter of 1 by the adjusted minute interval of several μm. The inner peripheral surface 21a of the outer cylinder bearing 21 and the outer peripheral surface 12a of the inner cylinder bearing 12 constitute a radial dynamic pressure bearing portion, and the rotary unit 2 performs radial rotation in the radial dynamic pressure bearing portion with respect to the main body fixed portion. Will be

The upper end surface 21bA of the outer cylinder bearing 21 faces the thrust surface 13aA of the upper thrust bearing 13A, and the lower end surface 21bB of the outer cylinder bearing 21 also has a lower thrust bearing 13bA.
The thrust surface 13aB of B constitutes a thrust dynamic pressure bearing portion, and the rotation unit 2 performs thrust rotation in the thrust dynamic pressure bearing portion relative to the main body fixed portion.

In the rotating device (optical deflecting device) shown in FIG. 1, a polygon mirror 22 having a regular polygonal shape whose end face is a mirror surface is provided on the rotating unit 2 so that the mirror center coincides with the rotation center of the rotating unit 2. Adjusted and installed.

A permanent magnet 23 for generating torque in the form of a ring of multiple magnetic pole pairs is fixedly provided on the bottom surface of the rotating unit 2 facing the support base plate 3. A printed circuit board 32 on which a plurality of magnet coils 31 are arranged on the same circle is mounted on the support base plate 3.
Inside, a Hall element 33 is attached as a detection element for detecting a change in the magnetic field. The Hall element 33 has a function as a speed sensor and a position sensor. The current to the magnet coil 4 is controlled based on the detection signal detected by the Hall element 33, and the polygon mirror 22
Is rotated at high speed.

Conventionally, in a rotating device using a dynamic pressure bearing, the upper limit of the dynamic balance is defined by the vibration limit, the lower limit is defined by the stability limit, and the adjustment is performed within the range between the upper limit and the lower limit as an allowable adjustment range. In contrast, by providing the rotating unit according to the present invention with a means for applying an external force in a constant radial direction, rotation instability does not occur even in a region where the dynamic balance is small, and as a result, the correction region for dynamic balance adjustment is expanded. As a result, the production margin is improved.

The production margin is improved by expanding the allowable adjustment range of the radial gap in the radial dynamic pressure bearing portion.

As a result of being able to adjust even in a region where the dynamic balance is small, external vibration is reduced.

As a result of suppressing the unstable vibration during rotation, abnormal noise generated during rotation is reduced.

[0016] As a result of avoiding wear at the dynamic pressure bearing portion due to unstable vibration during rotation, the life of the rotating device that can be used is extended.

Since stable rotation can be obtained even in a high-speed rotation range, it is possible to further increase the speed.

The following effects are obtained.

The rotating device described as an example of the optical deflecting device of the present invention is a rotating device having a dynamic pressure bearing that does not cause rotational instability even in a region where the dynamic balance is small, and will be described in detail in the following embodiments. .

(Embodiment 1) An embodiment of the invention according to claim 1, wherein a permanent magnet is used as a means for applying an external force in a fixed radial direction to the rotating unit, and an attractive force by a magnetic force in one direction. Therefore, even in a region where the dynamic balance is small, the rotating device is a dynamic pressure bearing in which rotation instability does not occur during high-speed rotation.

FIG. 2 is an explanatory view of the first embodiment.
2A is a side sectional view, and FIG. 2B is a plan view.
The rotating rotating unit 2 is provided with a ring-shaped magnetic body 51 having magnetism such as iron, for example.
Alternatively, one or a plurality of permanent magnets 52 are provided in the housing 50 fixed so as to cover the side surface of the rotating device, and the rotating unit 2 is kept constant in the radial direction by an attractive force generated between the magnetic body 51 and the permanent magnet 52. Of tensile force. The tensile force at this time is determined by the magnetic force of the permanent magnet 52, the distance D between the permanent magnet 52 and the magnetic body 51, and the like. The adjustment and setting of the pulling force to prevent the occurrence of the tension are performed.

In this embodiment, the rotation unit 2
When the member constituting is a magnetic body, the outer periphery thereof is formed in a ring shape to substitute for the magnetic body 51, and the magnetic body 51 does not need to be newly provided on the rotating unit 2 as a separate part.

(Embodiment 2) An embodiment of the invention according to claim 2, wherein the means for applying an external force to the rotating unit in a constant radial direction is provided by an electromagnetic force of a driving motor for driving and rotating the rotating unit. This is a rotating device using a dynamic pressure bearing that does not cause rotational instability even in a region with a small dynamic balance by using the function.

The drive motor (polygon motor) of the rotating device (optical deflecting device) shown in FIG. 1 has a plurality of ring-shaped magnet coils 31 and a plurality of ring-shaped magnetic pole pairs shown in FIG. And a permanent magnet 23. FIG. 3A is a plan view showing an arrangement relationship of the magnet coils 31 provided on the printed circuit board 32, and FIG. 3B is a plan view of the permanent magnet 23 fixed to the rotating unit 2 rotating at high speed. . In the present embodiment, as shown in FIG. 3A, six sets of magnet coils 31 (31a1, 31a) are provided.
a2...) are equally arranged on the same circle, and the magnet coils 31a1 and 31a2 are located to face each other. Similarly, the magnet coils 31b1 and 31b2 and the magnet coil 31c
1 and 31c2 are located facing each other. Hall elements 33 for detecting changes in the magnetic field are provided in the magnet coils 31a1, 31b1, and 31c1, respectively. The three Hall elements have functions as a speed sensor and a position sensor. Also, the magnet coil 31
(31a1, 31a2...)
As shown in the figure, a permanent magnet 23 having four poles and eight poles is provided on the same circle. The control unit controls the current of the magnet coil 31 based on the detection signal detected by the Hall element 33, and the rotation unit 2 rotates at high speed.

Here, the high speed rotation of the rotary unit 2 is performed as follows. That is, as shown in FIG. 4A, a permanent magnet 23 and a plurality of magnet coils 3 provided in a ring shape.
1, the center of the magnetic force of the permanent magnet 23 and the center of the magnetic force generated by the energization of the magnet coil 31 are provided on a circle having the same radius around the rotation axis of the inner cylindrical bearing 12. And the magnetic force of the magnet coil 31 at the time of energization act as an attractive force or a repulsive force in the rotation direction of the rotating unit 2, and the above attractive force or repulsive force is inherited by switching the energization to the plurality of magnet coils 31 to rotate. The high-speed rotation of the unit 2 is performed.

In the rotating device of the present embodiment, a plurality of ring-shaped magnet coils 31 are arranged eccentrically with respect to the axis of the inner cylinder bearing.
2 shows a state where the eccentricity is provided. With such a configuration, between the permanent magnet 23 positioned in the eccentric direction and the magnet coil 31 that is passed therethrough and energized, the rotating unit 2 is radially moved in addition to the attractive force or repulsive force in the rotating direction of the rotating unit 2. A pulling or pressing force acts in the direction.

In the rotating device of the present embodiment, the external force acting on the rotating unit 2 in one direction in the radial direction generated during the rotation of the driving motor causes the dynamic pressure bearing portion of the rotating device to have a small dynamic balance. Also, rotation instability does not occur during high-speed rotation.

(Embodiment 3) An embodiment of the invention according to claim 3, wherein the means for applying an external force to the rotating unit in a constant radial direction is accompanied by the rotation of the rotating device rotating in the housing. This is a rotating device that uses a difference in air pressure around the rotating unit generated as a result, and is a dynamic pressure bearing that does not generate rotational instability even in a region where dynamic balance is small.

FIG. 5 is an explanatory diagram of the third embodiment. FIG. 5 (a) shows the flow of air generated as the rotating unit 2 rotates at a high speed. In the vicinity of the rotating unit 2, the linear velocity (wind speed) near the peripheral speed of the rotating unit 2 is used. The movement is performed and the rotating unit 2
As one moves away from the vehicle, the moving speed of the air drops sharply.

FIG. 5B is a plan view showing an example of the present embodiment. A near wall surface 81 is provided on the inner wall surface of the housing 50 at a small distance from the outer circumferential surface of the rotary unit 2. The rotation upstream side end portion 81a is provided with a proximity gradient wall surface 82a having a shape gradually moving away from the outer periphery of the rotation unit 2 on the rotation upstream side. With this configuration, the airflow generated by the rotation of the rotary unit 2 is pushed in while moving between the proximity gradient wall surface 82a and the rotary unit 2, and the air becomes a compressed steady state,
At the position Pa in the drawing, the pressing force of Fa acts in the radial direction of the rotating unit 2 due to the difference in air pressure.

An adjacent wall surface 8 located at a small distance from the outer peripheral surface of the rotary unit 2 on the inner wall surface of the housing 50.
The one rotation downstream end portion 81b is provided with a near-gradient wall surface 82b having a shape gradually moving away from the outer peripheral surface of the rotary unit 2 on the downstream side of the rotation. With this configuration, the air very close to the rotary unit 2 near the position Pb in the figure is taken away with the rotation of the rotary unit 2,
The air flow for replenishing the air becomes insufficient and the air becomes lean and steady. At the position Pb, a negative pressure (tensile force) of Fb acts in the radial direction of the rotary unit 2 due to a difference in air pressure.

For example, a near wall 81 having a slight gap is provided between the outer peripheral surface of the rotating unit 2 and the inner wall surface of the housing 50 as described above, and the rotating unit 2 is rotated in the radial direction. Due to the application of the external force due to the air pressure in a certain direction, rotation instability does not occur during high-speed rotation even in a region where the dynamic balance is small in the dynamic pressure bearing portion of the rotating device.

[0033]

Conventionally, in a rotating device using a dynamic pressure bearing, the upper limit of the dynamic balance is defined by the vibration limit and the lower limit is defined by the stability limit, and the adjustment is performed within the range between the upper limit and the lower limit as an allowable adjustment range. On the other hand, the present invention (claims 1, 2, 2)
By providing a means for applying an external force in a constant radial direction to the rotating unit according to 3), rotation instability does not occur even in a region where dynamic balance is small,
As a result, the correction area for dynamic balance adjustment is expanded, and as a result, the production margin is improved.

The production margin is improved by increasing the allowable adjustment range of the gap in the radial direction in the radial dynamic pressure bearing portion.

As a result of being able to adjust even in a region where the dynamic balance is small, external vibration is reduced.

As a result of suppressing the unstable vibration during rotation, abnormal noise generated during rotation is reduced.

As a result of avoiding wear in the dynamic pressure bearing portion due to unstable vibration during rotation, the life of the rotating device that can be used is extended.

Since stable rotation can be obtained even in the high-speed rotation range, it is possible to further increase the speed.

The following effects were obtained.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a rotating device.

FIGS. 2A and 2B are a cross-sectional view and a plan view of Embodiment 1. FIGS.

FIG. 3 is a plan view of a magnet coil and a permanent magnet.

FIG. 4 is an explanatory diagram of Embodiment 2.

FIG. 5 is an explanatory diagram of Embodiment 3.

FIG. 6 is a sectional view showing a configuration of a rotating device.

[Explanation of symbols]

 2 Rotation unit 11 Radial shaft 12 Inner cylinder bearing 13A Upper thrust bearing 13B Lower thrust bearing 21 Outer cylinder bearing 23 Permanent magnet 31 Magnet coil 50 Housing 51 Magnetic material 52 Permanent magnet 81 Near wall surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H045 AA14 AA24 AA49 AA53 3J011 AA20 BA02 3J102 AA01 AA08 BA04 BA19 CA10 DA03 DA10 DA12 GA02

Claims (4)

[Claims] 1. A rotating device having a dynamic pressure bearing that rotates between a rotating unit having an outer cylinder bearing and an inner cylinder bearing fixed to a base or a housing, wherein the rotating unit has a ring-shaped magnetic body. And a permanent magnet is provided on the base or the housing at a position facing the magnetic body so as to generate an attraction force in one direction. 2. A rotating device having a dynamic pressure bearing which rotates between a rotating unit having an outer cylinder bearing and an inner cylinder bearing fixed on a base, wherein the rotating unit has a permanent magnet for generating torque. Is established,
A rotating device, wherein a plurality of magnet coils provided in a ring shape are eccentrically arranged on an inner cylinder bearing on the base. 3. A rotating device having a dynamic pressure bearing which rotates between a rotating unit having an outer cylinder bearing and an inner cylinder bearing fixed in a housing, wherein an outer peripheral surface of the rotating unit and an inner surface of the housing are provided. A narrow portion for generating air pressure at a distance from the rotating device. 4. The rotation device according to claim 1, wherein the rotation unit has a polygon mirror.