JPH0972337A - Supporting device of movable body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a structure by providing with a first ring magnet which is fit to a magnetic bearing on a movable body outer peripheral surface and in which the axis of easy magnetization of magnetic powder is oriented in a radial direction, and a second ring magnet for covering the first ring magnet at fine clearances, and in which the axis of easy magnetization of magnetic powder is oriented on a radial direction so as to oppose a same pole to each other. SOLUTION: When an S pole is applied on a fixing disc 13 side, and an N pole is applied on an upper fixing base 16 side and an lower fixing base 12 side and pressure is applied, a magnetic field from the upper fixing base 16 is repulsed from the magnetic field of the lower fixing base 12 side, it is faced to the S pole of the fixing base 13 side, and the magnetic field from the lower fixing base 12 is faced to the S pole of the fixing disk 13 side. The axis of easy magnetization of magnetic powder 14 is completed, the magnetization direction of a ring shaped differential direction Nd magnet 17 is faced from a center part to an outside, and it is equally magnetized radially. The ring shaped differential direction Nd magnet 18 of an inner circumferential diameter whose diameter is finely larger than the outer peripheral diameter of the inner circumferential ring magnet 17 is formed. The supporting device of a movable body which is not brought into contact with the inner circumferential part of the outer peripheral ring magnet 18 is thus provided in a simple structure.

Description

Detailed Description of the Invention

[0001]

[0001]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable body supporting device using a magnetic bearing.

[0003]

[0002]

[0004]

2. Description of the Related Art Conventionally, there have been various methods such as a bearing as a bearing for smoothly rotating a rotating machine. In particular, as non-contact type bearings, pneumatic bearings utilizing high pressure air, magnetic bearings utilizing magnetic repulsion of magnets, and the like are known.

FIG. 5 (a) shows an example of a magnetic bearing as a conceptual diagram. That is, there is a cylindrical movable body inside the fixed portion of a prism having a circular hollow structure, and a magnetic bearing of this movable body will be described.

In FIG. 5 (a), four prism-shaped permanent magnets 2 are arranged on the outer peripheral edge of a cylindrical movable portion 1 in, for example, four directions at right angles. At this time, the S pole of the permanent magnet 2 is arranged so as to face the outer peripheral side, for example. In addition, the fixing portion 3 having a hollow structure
In contrast, at a position facing the permanent magnet 2 of the movable body 1,
A prismatic permanent magnet or electromagnet 4 is arranged so that the south pole faces inward.

[0007]

In the movable body supporting apparatus having the structure shown in FIG. 5B, the movable portion 1 is suspended in the central portion of the fixed portion 3 by the magnetic repulsive force of the magnets provided in the movable portion 1 and the fixed portion 3. It is possible to use as a non-contact type bearing that smoothly rotates the movable portion 1 in the center of the fixed portion 3 (direction of arrow (A) in the figure).

Further, since the movable part 1 floats in the center of the fixed part 3 in a non-contact manner, the movable part 1 can be moved inside the fixed part 3 in addition to the use as a bearing for rotating the movable part 1. It can be used for a non-contact type sliding device that slides in the direction B).

By increasing the number of permanent magnets and electromagnets, the stability of rotation and sliding operation can be improved.

[0010]

[0004]

[0011]

As described above, magnetic bearings and sliding devices that utilize the magnetic repulsive force of magnets have problems such as driving load due to contact friction and heat generation due to contact friction, which are found in contact types. Since it does not occur, it is used in a wide range of fields. However, in order to realize stable operation as a bearing or a sliding device, a large number of permanent magnets or electromagnets are required as described above, and the magnetic force must be made uniform by the permanent magnets or electromagnets, resulting in a complicated structure. It had the drawback that

The present invention has been made in view of the above problems, and an object thereof is to provide a supporting device for a movable body having a simple structure.

[0013]

[0005]

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a supporting device for a movable body according to claim 1 includes a magnetic bearing for supporting the movable body in a radial direction. A magnetic bearing, which is a supporting device for a movable body, has a first ring-shaped magnet fitted and fixed to an outer peripheral surface of the movable body and having a magnetic easy axis of magnetic particles oriented in a radial direction, and a first ring-shaped magnet. A second ring-shaped magnet is provided, which is surrounded by a minute gap and in which the easy axis of magnetization of the magnetic powder is oriented in the radial direction so that the same pole as the first ring-shaped magnet faces.

[0015]

Further, the movable body supporting apparatus according to the first aspect is characterized in that the movable body is a lens barrel to which an objective lens for optical recording / reproducing is attached.

[0016]

[0007]

[0017]

The movable body supporting apparatus of the present invention includes a first ring-shaped magnet, which is fitted and fixed to the outer peripheral surface of the movable body, and has an axis of easy magnetization of magnetic particles oriented in the radial direction, and a first ring-shaped magnet. A second magnet which is surrounded by a minute gap and whose easy axis of magnetization of the magnetic powder is oriented in the radial direction so that the same pole as that of the first ring-shaped magnet faces
Since the first ring-shaped magnet and the second ring-shaped magnet have the same magnetic force, the first ring-shaped magnet and the second ring-shaped magnet repel each other. Therefore, the first ring-shaped magnet is located substantially at the center of the second ring-shaped magnet, and it is possible to support the movable body provided on the inner peripheral surface of the first ring-shaped magnet. .

In the movable body supporting device, the movable body may be a lens barrel to which an objective lens for optical recording / reproducing is attached.

[0019]

[0008]

[0020]

1 is a structural diagram of a molding apparatus for molding an anisotropic magnet used in an embodiment of the present invention. FIG.
A method for forming an anisotropic magnet will be briefly described with reference to (a) and (b). In FIG. 1A, reference numeral 10 is a rubber mold in which a concave portion is provided to match the shape of the anisotropic magnet (here, it is ring-shaped), 11 is a guide for fixing the rubber mold, 12 is a lower fixing base, 13 is a fixed board.

First, the recess of the rubber mold 10 is 2-3w.
A neodymium (Nd) -based magnetic powder 14 having a magnetic anisotropy in which a thermosetting resin such as t% of epoxy is mixed is inserted, and the magnetic powder 14 is filled while vertically and horizontally vibrating with a pushing rod 15.

Next, as shown in FIG. 1 (b), the fixing guide 11 is removed and the upper fixing base 16 is replaced with the magnetic powder 1
4 is placed on the rubber mold 10 in which it is inserted.

[0023]

Then, the upper fixed table 16 and the lower fixed table 12
While applying a magnetic field (in the direction of FIG. 1B, from the lower fixing base 12 to the upper fixing base 16) greater than the coercive force of the magnetic powder between
The magnetic powder 14 is pressed at a pressure of 10 tf / cm ² to align the easy axes of magnetization.

As a result, the ring-shaped anisotropic Nd magnet 17 is obtained. Here, the easy axis of magnetization means the direction in which the energy required to magnetize the magnetic particles is the smallest. Further, the anisotropic Nd magnet 14 facilitates orientation of the easy axis of magnetization by applying pressure isotropically, and by applying a magnetic field from the outside, the magnetization direction of the magnetic powder is changed in the applied magnetic field direction. Get together. The magnet thus obtained is called an anisotropic magnet magnetized in the applied magnetic field direction.

Then, at one end, the ring-shaped anisotropic Nd magnet 1
A magnetic field in the opposite direction to that described above is applied to 7 to demagnetize (to bring the entire magnet into a non-magnetized state) and then taken out from the rubber mold 10.

[0026]

Next, as shown in FIG. 2A, the fixed platen 1
The S pole is applied to the third side, and the N pole is applied to the upper fixed base 16 side and the lower fixed base 12 side, respectively, and the same pressure as that described above is applied.

The magnetic field from the upper fixed base 16 is repelled by the magnetic field on the lower fixed base 12 side and goes to the S pole on the fixed platen 13 side. Similarly, the magnetic field from the lower fixed base 12 is directed to the S pole on the fixed platen 13 side.

As a result, the magnetization direction of the ring-shaped anisotropic Nd magnetic powder 17 is uniformly magnetized radially (radially) from the central portion toward the outside. FIG. 2B shows the state of magnetization, where N is on the inner peripheral side of the ring-shaped anisotropic Nd magnet 17.
It becomes a pole, and the outer peripheral side is magnetized to the S pole. This is the inner ring magnet 17 as the first ring magnet.

[0029]

Then, similarly to the above, the inner ring magnet 17
The ring-shaped anisotropic Nd magnet 18 having an inner peripheral diameter smaller than the outer peripheral diameter of 1 is molded. At this time, when the N pole is applied to the fixed platen 13 side and the S pole is applied to the upper fixed portion 16 side and the lower fixed portion 12 side, as shown in FIG. An anisotropic magnet magnetized to have an S pole on the peripheral side and an N pole on the outer peripheral side can be obtained. This is the outer ring magnet 18 as the second ring magnet.

FIG. 3 is a structural view of a movable body supporting apparatus according to the first embodiment of the present invention.

In FIG. 3, two inner peripheral ring magnets 17 are fitted and fixed to the outer peripheral portion of a cylindrical movable body 19 at intervals. An outer peripheral ring magnet 18 having, for example, substantially the same length as the movable body 19 is arranged on the same central axis of the inner peripheral ring magnet 17.

[0032]

As shown in FIG. 3B, an S pole is arranged on the outer peripheral portion of the inner ring magnet 17, and an S pole is arranged on the inner peripheral portion of the outer ring magnet 18. Further, since the inner diameter of the outer peripheral ring magnet 18 is designed to be slightly larger than the outer peripheral diameter of the inner peripheral ring magnet 17, it is very small between the inner peripheral surface of the outer peripheral ring magnet 18 and the outer peripheral surface of the inner peripheral ring magnet 17. A gap is constructed. Further, since the uniform magnetic force is present on all the inner peripheral surfaces of the outer peripheral ring magnet 18 and the uniform magnetic force is present on all the outer peripheral surfaces of the inner peripheral ring magnet 17, the action of the uniform magnetic repulsive force by the mutual magnets is exerted. Thus, a supporting device for a movable body that does not contact the inner peripheral portion of the outer peripheral ring magnet 18 is configured.

In the first embodiment of the present invention, two inner peripheral ring magnets 17 are fixedly mounted with a space therebetween, but the inner peripheral ring magnet 17 is replaced by the outer peripheral ring magnet 18.
The length may be substantially the same. It goes without saying that the same effect can be obtained even if the configuration is changed depending on the shape of the movable body.

[0034]

A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a partial schematic view of a movable body to which an objective lens for optical recording and reproduction is attached. The parts used in the first embodiment of the present invention are designated by the same reference numerals, and the duplicated description will be omitted.

In FIG. 4A, reference numeral 20 is an objective lens provided at the center of the hollow cylindrical movable body 19, 21 is a ring-shaped stopper fitted and fixed to a part of the movable body 19, and 22 is movable. The focus coil is wound around the outer periphery of the body 19. The inner ring magnet 17 is fitted and fixed to the outer peripheral portion of the movable body 19.

An outer peripheral ring magnet 18 fitted and fixed to the frame 23 of the optical recording / reproducing apparatus has a minute gap with respect to the inner peripheral ring magnet 17 on the outer peripheral portion of the inner peripheral ring magnet 17. Surrounded and provided.

[0037]

The inner ring magnet 17 and the outer ring magnet 18 in the second embodiment of the present invention have substantially the same length.
The outer peripheral surface of the inner ring magnet 17 and the inner peripheral surface of the outer ring magnet 18 are mirror-finished. That is, the movable body 19 is a lens barrel including the inner ring magnet 17.

The movable part 30 composed of the objective lens 20, the movable body 19, the inner ring magnet 17 and the focus coil 22 is placed on the frame 23 by a stopper 21 fitted and fixed to the outer peripheral surface of the movable body 19. Therefore, the position of the objective lens 20 is regulated so as not to approach the optical disk substrate surface by a specified value or more. Also, the focus coil 2
An annular high-permeability metal plate 24 at a position facing 2; an annular magnet 25; and a disk-shaped high-permeability metal yoke 26 in which a center portion of a hollow cylindrical convex portion is integrally formed in the central portion. Are integrally fixed to the frame 23.

[0039]

As described above, the movable portion 30 is arranged without contacting the central portion of the outer ring magnet 18 by the action of the uniform magnetic repulsion force of the inner ring magnet 17 and the outer ring magnet 18. Similarly, the focus coil 22 is arranged at the center of the gap between the plate 24 and the center pole.

FIG. 4B shows a state in which a drive current is applied to the focus coil 22 and the movable portion 30 is displaced toward the plate 24 side.

When an electric current is applied to the focus coil 22 placed in the air gap magnetic field between the plate 24 and the center pole portion of the yoke 26, an attractive magnetic force is generated by the magnetic flux of the focus coil 22 in the direction of the arrow in the figure. Driving force is generated.

For this reason, the movable portion 30 integrated with the focus coil 22 is displaced by the specified current at one end, and the focus coil 22 is displaced to a position substantially in the center of the yoke 26.

After that, the magnetic force from the focus coil 22 changes in accordance with a control current from a focus control generating circuit (not shown), and the entire movable portion 30 is displaced vertically (in the direction of the arrow in FIG. 4B). With this, focus control for accurately irradiating the light beam condensed by the objective lens on the surface of the optical disc substrate 27 becomes possible.

[0044]

[0016]

[0045]

According to the movable body supporting apparatus of the present invention, the first ring-shaped magnet, which is fitted and fixed to the outer peripheral surface of the movable body and which is uniformly magnetized in a radial direction, has a minute gap. Since the first ring-shaped magnet and the second ring-shaped magnet are provided and surrounded, and the second ring-shaped magnet is uniformly magnetized radially so that the same pole faces the first ring-shaped magnet, the first ring-shaped magnet and the second ring-shaped magnet are provided. And repel each other with the same magnetic force. Therefore, the first ring-shaped magnet is located substantially at the center of the second ring-shaped magnet, and the axial rotation and the axial movement of the movable body can be smoothed with a simple structure.

[0046]

Further, as described above, the inner ring magnet 1
The outer peripheral surface of 7 and the inner peripheral surface of the outer peripheral ring magnet 18 are mirror-finished and face each other with a minute gap. Further, since the stopper 21 fitted and fixed to the outer peripheral surface of the movable body 19 is provided, by using the movable body supporting device of the present invention as a lens barrel to which an objective lens for optical recording / reproducing is attached, When the movable portion 30 is rapidly displaced, the air that has passed through the minute gap between the inner ring magnet 17 and the outer ring magnet 18 is blocked by the stopper 21 to generate an appropriate air resistance, which acts as a damping effect. To do.

As a result, a member such as a suspension is not required, and it is possible to provide an optical disk pickup supporting device which is easy to assemble and has a simple structure.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a molding apparatus for molding an anisotropic magnet used in an example of the present invention.

FIG. 2 is a conceptual diagram of a method of applying a pulsed magnetic field to obtain an anisotropic magnet used in an example of the present invention.

FIG. 3 is a structural diagram of a movable body supporting apparatus according to a first embodiment of the present invention.

FIG. 4 is a structural diagram of an optical recording / reproducing optical pickup unit according to a second embodiment of the present invention.

FIG. 5 is a conceptual diagram of a magnetic bearing in a conventional example.

[Explanation of symbols]

 17 ・ ・ Inner ring magnet 18 ・ ・ Outer ring magnet 19 ・ ・ Movable body 20 ・ ・ Objective lens 21 ・ ・ Stopper 22 ・ ・ Focus coil 23 ・ ・ Frame 24 ・ ・ Plate 25 ・ ・ Magnet 26 ・ ・ Yoke 27 ・.Optical disk substrate 30..Movable part

[Procedure amendment]

[Submission date] October 31, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Detailed description of the invention

[Correction method] Change

[Correction contents]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable body supporting device using a magnetic bearing.

[0002]

2. Description of the Related Art Conventionally, there have been various methods such as a bearing as a bearing for smoothly rotating a rotating machine. In particular, as non-contact type bearings, pneumatic bearings utilizing high pressure air, magnetic bearings utilizing magnetic repulsion of magnets, and the like are known. FIG. 5A shows an example of a magnetic bearing as a conceptual diagram. That is, there is a cylindrical movable body inside the fixed portion of a prism having a circular hollow structure, and a magnetic bearing of this movable body will be described. In FIG. 5A, the cylindrical movable part 1
For example, four prism-shaped permanent magnets 2 are arranged in the outer peripheral edge portion of 4 in four directions at right angles. At this time, the S pole of the permanent magnet 2 is arranged so as to face the outer peripheral side, for example. Further, with respect to the fixed portion 3 having a hollow structure, a prismatic permanent magnet or electromagnet 4 is arranged at a position facing the permanent magnet 2 of the movable body 1 so that the S pole faces inward.

In the movable body supporting apparatus having the structure shown in FIG. 5B, the movable portion 1 is suspended in the central portion of the fixed portion 3 by the magnetic repulsive force of the magnets provided in the movable portion 1 and the fixed portion 3. It is possible to use as a non-contact type bearing that smoothly rotates the movable portion 1 in the center of the fixed portion 3 (direction of arrow (A) in the figure). Further, the movable part 1 is fixed to the fixed part 3.
Since it floats in the center of the movable part in a non-contact manner, it is of a non-contact type in which the movable part 1 is slid in the fixed part 3 in the direction of the arrow (B) in the figure, in addition to the use as a bearing for rotating the movable part 1. It can be used for a sliding device. Further, by increasing the number of permanent magnets or electromagnets, it is possible to improve the stability of rotation and sliding operation.

[0004]

As described above, magnetic bearings and sliding devices that utilize the magnetic repulsive force of magnets have problems such as driving load due to contact friction and heat generation due to contact friction, which are found in contact types. Since it does not occur, it is used in a wide range of fields. However, in order to realize stable operation as a bearing or a sliding device, a large number of permanent magnets or electromagnets are required as described above, and the magnetic force must be made uniform by the permanent magnets or electromagnets, resulting in a complicated structure. It had the drawback that The present invention has been made in view of the above problems, and an object thereof is to provide a support device for a movable body having a simple structure.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a supporting device for a movable body according to claim 1 includes a magnetic bearing for supporting the movable body in a radial direction. A magnetic bearing, which is a supporting device for a movable body, has a first ring-shaped magnet fitted and fixed to an outer peripheral surface of the movable body and having a magnetic easy axis of magnetic particles oriented in a radial direction, and a first ring-shaped magnet. A second ring-shaped magnet is provided, which is surrounded by a minute gap and in which the easy axis of magnetization of the magnetic powder is oriented in the radial direction so that the same pole as the first ring-shaped magnet faces.

Further, the movable body supporting apparatus according to the first aspect is characterized in that the movable body is a lens barrel to which an objective lens for optical recording / reproducing is attached.

[0007]

The movable body supporting apparatus of the present invention includes a first ring-shaped magnet, which is fitted and fixed to the outer peripheral surface of the movable body, and has an axis of easy magnetization of magnetic particles oriented in the radial direction, and a first ring-shaped magnet. A second magnet which is surrounded by a minute gap and whose easy axis of magnetization of the magnetic powder is oriented in the radial direction so that the same pole as that of the first ring-shaped magnet faces
Since the first ring-shaped magnet and the second ring-shaped magnet have the same magnetic force, the first ring-shaped magnet and the second ring-shaped magnet repel each other. Therefore, the first ring-shaped magnet is located substantially at the center of the second ring-shaped magnet, and it is possible to support the movable body provided on the inner peripheral surface of the first ring-shaped magnet. . Further, in the movable body supporting device, the movable body may be a lens barrel to which an objective lens for optical recording / reproducing is attached.

[0008]

1 is a structural diagram of a molding apparatus for molding an anisotropic magnet used in an embodiment of the present invention. FIG.
A method for forming an anisotropic magnet will be briefly described with reference to (a) and (b). In FIG. 1A, reference numeral 10 is a rubber mold in which a concave portion is provided to match the shape of the anisotropic magnet (here, it is ring-shaped), 11 is a guide for fixing the rubber mold, 12 is a lower fixing base, 13 is a fixed board. First,
While inserting neodymium (Nd) -based magnetic powder 14 having a magnetic anisotropy mixed with a thermosetting resin such as epoxy of 2 to 3 wt% into the concave portion of the rubber mold 10 and applying vertical and horizontal vibration with the pushing rod 15. The magnetic powder 14 is filled. Next, FIG.
As shown in (b), the fixing guide 11 is removed, and the upper fixing base 16 is put on the rubber mold 10 in which the magnetic powder 14 is inserted instead.

Then, the upper fixed table 16 and the lower fixed table 12
While applying a magnetic field (in the direction of FIG. 1B, from the lower fixing base 12 to the upper fixing base 16) greater than the coercive force of the magnetic powder between
The magnetic powder 14 is pressed at a pressure of ˜1 otf / cm ² to align the easy axes of magnetization of the magnetic particles 14. As a result, the ring-shaped anisotropic Nd magnet 1
7 is obtained. Here, the easy axis of magnetization means the direction in which the energy required to magnetize the magnetic particles is the smallest. Further, the anisotropic Nd magnet 14 facilitates orientation of the easy axis of magnetization by applying pressure isotropically, and by applying a magnetic field from the outside, the magnetization direction of the magnetic powder is changed in the applied magnetic field direction. Get together. The magnet thus obtained is called an anisotropic magnet magnetized in the applied magnetic field direction. After that, a magnetic field in the opposite direction to the above is applied to the ring-shaped anisotropic Nd magnet 17 at one end to demagnetize (the entire magnet is not magnetized), and then the rubber mold 10 is taken out.

Next, as shown in FIG. 2A, the fixed platen 1
The S pole is applied to the third side, and the N pole is applied to the upper fixed base 16 side and the lower fixed base 12 side, respectively, and the same pressure as that described above is applied. The magnetic field from the upper fixed base 16 is repelled by the magnetic field on the lower fixed base 12 side, and goes to the S pole on the fixed platen 13 side. Similarly, the magnetic field from the lower fixed base 12 is directed to the S pole on the fixed platen 13 side. As a result, the magnetization direction of the ring-shaped anisotropic Nd magnetic powder 17 is uniformly magnetized radially (in the radial direction) from the center to the outside. FIG.
(B) shows the state of magnetization, and the ring-shaped anisotropy N
The inner peripheral side of the d-magnet 17 has an N pole, and the outer peripheral side is magnetized with an S pole. This is the inner ring magnet 17 as the first ring magnet.

Then, similarly to the above, the inner ring magnet 17
The ring-shaped anisotropic Nd magnet 18 having an inner peripheral diameter smaller than the outer peripheral diameter of 1 is molded. At this time, when the N pole is applied to the fixed platen 13 side and the S pole is applied to the upper fixed portion 16 side and the lower fixed portion 12 side, as shown in FIG. An anisotropic magnet magnetized to have an S pole on the peripheral side and an N pole on the outer peripheral side can be obtained. This is the outer ring magnet 18 as the second ring magnet. FIG. 3 is a structural diagram of a movable body supporting apparatus according to a first embodiment of the present invention. In FIG. 3, two inner ring magnets 17 are fitted and fixed to the outer peripheral portion of a cylindrical movable body 19 at intervals. An outer peripheral ring magnet 18 having, for example, substantially the same length as the movable body 19 is arranged on the same central axis of the inner peripheral ring magnet 17.

As shown in FIG. 3B, an S pole is arranged on the outer peripheral portion of the inner ring magnet 17, and an S pole is arranged on the inner peripheral portion of the outer ring magnet 18. Further, since the inner diameter of the outer peripheral ring magnet 18 is designed to be slightly larger than the outer peripheral diameter of the inner peripheral ring magnet 17, it is very small between the inner peripheral surface of the outer peripheral ring magnet 18 and the outer peripheral surface of the inner peripheral ring magnet 17. A gap is constructed. Further, since the uniform magnetic force is present on all the inner peripheral surfaces of the outer peripheral ring magnet 18 and the uniform magnetic force is present on all the outer peripheral surfaces of the inner peripheral ring magnet 17, the action of the uniform magnetic repulsive force by the mutual magnets is exerted. Thus, a supporting device for a movable body that does not contact the inner peripheral portion of the outer peripheral ring magnet 18 is configured. In the first embodiment of the present invention, the two inner peripheral ring magnets 17 are fixedly mounted with a space therebetween, but the inner peripheral ring magnets 17 are attached to the outer peripheral ring magnets 18.
The length may be substantially the same. It goes without saying that the same effect can be obtained even if the configuration is changed depending on the shape of the movable body.

A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a partial schematic view of a movable body to which an objective lens for optical recording and reproduction is attached. The parts used in the first embodiment of the present invention are designated by the same reference numerals, and the duplicated description will be omitted. In FIG. 4A, reference numeral 20 is an objective lens provided in the center of the hollow cylindrical movable body 19, 21 is a ring-shaped stopper fitted and fixed to a part of the movable body 19, and 22 is the movable body 19. The focus coil is wound around the outer periphery. And the movable body 19
An inner peripheral ring magnet 17 is fitted and fixed to the outer peripheral portion of. Further, the outer peripheral portion of the inner peripheral ring magnet 17 is surrounded by the outer peripheral ring magnet 18 fitted and fixed to the frame 23 of the optical recording / reproducing apparatus with a minute gap with respect to the inner peripheral ring magnet 17. It is provided.

The inner ring magnet 17 and the outer ring magnet 18 in the second embodiment of the present invention have substantially the same length.
The outer peripheral surface of the inner ring magnet 17 and the inner peripheral surface of the outer ring magnet 18 are mirror-finished. That is, the movable body 19 is a lens barrel including the inner ring magnet 17.
The movable part 30 including the objective lens 20, the movable body 19, the inner ring magnet 17, and the focus coil 22 is placed on the frame 23 by the stopper 21 fitted and fixed to the outer peripheral surface of the movable body 19. , Objective lens 20
Position is regulated so as not to approach the optical disk substrate surface more than the specified value. Further, a disk-shaped metal having a high magnetic permeability, which is integrally formed with an annular high-permeability metal plate 24 at a position facing the focus coil 22, an annular magnet 25, and a hollow cylindrical convex center pole in the central portion. The yoke 26 is integrally fixed to the frame 23.

As described above, the movable portion 30 is arranged without contacting the central portion of the outer ring magnet 18 by the action of the uniform magnetic repulsion force of the inner ring magnet 17 and the outer ring magnet 18. Similarly, the focus coil 22 is arranged at the center of the gap between the plate 24 and the center pole. FIG. 4B shows a state in which a drive current is applied to the focus coil 22 and the movable portion 30 is displaced toward the plate 24 side. When a current is applied to the focus coil 22 placed in the air gap magnetic field between the plate 24 and the center pole portion of the yoke 26, an attractive magnetic force is generated by the magnetic flux of the focus coil 22, and the driving force is increased in the direction of the arrow in the figure. Occurs. Therefore, the movable portion 30 integrated with the focus coil 22 is displaced by the specified current at one end, and the focus coil 22 is displaced to a position substantially in the center of the yoke 26.
After that, the magnetic force from the focus coil 22 changes according to a control current from a focus control generation circuit (not shown), and the entire movable part 30 is displaced up and down (in the direction of the arrow in FIG. 4B) to thereby move the objective. Focus control for accurately irradiating the optical beam condensed by the lens on the surface of the optical disc substrate 27 becomes possible.

[0016]

According to the movable body supporting apparatus of the present invention, the first ring-shaped magnet, which is fitted and fixed to the outer peripheral surface of the movable body and which is uniformly magnetized in a radial direction, has a minute gap. Since the first ring-shaped magnet and the second ring-shaped magnet are provided and surrounded, and the second ring-shaped magnet is uniformly magnetized radially so that the same pole faces the first ring-shaped magnet, the first ring-shaped magnet and the second ring-shaped magnet are provided. And repel each other with the same magnetic force. Therefore, the first ring-shaped magnet is located substantially at the center of the second ring-shaped magnet, and the axial rotation and the axial movement of the movable body can be smoothed with a simple structure.

Further, as described above, the inner ring magnet 1
The outer peripheral surface of 7 and the inner peripheral surface of the outer peripheral ring magnet 18 are mirror-finished and face each other with a minute gap. Further, since the stopper 21 fitted and fixed to the outer peripheral surface of the movable body 19 is provided, by using the movable body supporting device of the present invention as a lens barrel to which an objective lens for optical recording / reproducing is attached, When the movable portion 30 is rapidly displaced, the air that has passed through the minute gap between the inner ring magnet 17 and the outer ring magnet 18 is blocked by the stopper 21 to generate an appropriate air resistance, which acts as a damping effect. To do. As a result, a member such as a suspension is not required, and it is possible to provide an optical disk pickup supporting device that is easy to assemble and has a simple structure.

Claims (2)

[Claims] 1. A support device for a movable body having a magnetic bearing for supporting the movable body in a radial direction, wherein the magnetic bearing is fitted and fixed to an outer peripheral surface of the movable body, and an easy axis of magnetization of magnetic particles in a radial direction. And a first ring-shaped magnet that is oriented in a circle, and surrounds the first ring-shaped magnet with a minute gap, and an easy axis of magnetization of magnetic particles in the radial direction so that the same pole faces the first ring-shaped magnet. And a second ring-shaped magnet in which the magnet is oriented. 2. The movable body supporting apparatus according to claim 1, wherein the movable body is a lens barrel to which an objective lens for optical recording / reproducing is attached.