JPH11295636A - Galvanomirror holding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a galvanomirror at a prescribed position by providing a movable side magnet as a magnet formed on one axial member and a fixed side magnet as a magnet arranged at a fixed part so as to face that movable side magnet. SOLUTION: A center pin 124 is composed of a permanent magnet, divided into two sections with a plane 124a including its central axis inbetween and respectively magnetized into N pole and S pole. Besides, concerning a ring- shaped magnet 140, two magnets having cross sections in the shape of circular arc half are bonded on end faces. Concerning a semi-ring magnet 141 on one side, the outer peripheral side is magnetized into N pole, the inner peripheral side is magnetized into S pole, concerning a semi-ring magnet 142 on the other side, the outer peripheral side is magnetized into S pole and the inner peripheral side is magnetized into N pole. Since a neutral plane 124a of the center pin 124 and a neutral plane 145 of the ring-shaped magnet 140 are balanced while being located on the same plane, excepting for the rotational driving time of the galvanomirror, the galvanomirror can always be held at the neutral position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvanometer mirror used for fine movement tracking or the like in an optical disk device or the like.

[0002]

Recently, the areal recording density is 1
Optical disk devices exceeding 0 Gbit / (inch) ² are being developed. In such an optical disk device, in order to perform tracking with high accuracy, a galvano mirror as a deflecting means is provided between the light source and the objective optical system facing the recording surface of the optical disk. By rotating the galvanomirror, the incident angle of the light beam on the objective optical system is slightly changed, and the light spot is slightly moved on the recording surface of the optical disk.

Generally, a pivot system is employed as a structure for rotatably supporting a galvanometer mirror. However, in this method, since the galvanomirror rotates freely, it is necessary to separately provide some equipment for holding the galvanomirror at a predetermined rotation position.

The present invention has been made in view of the above background, and has as its object to provide a galvanomirror holding structure capable of holding a galvanomirror at a predetermined rotational position. .

[0005]

In order to solve the above-mentioned problems, the galvanomirror holding structure of the present invention comprises (1) two shaft members provided at positions corresponding to the rotation shaft of the movable portion; 2) two bearings provided on the fixed portion and receiving the two shaft members, (3) a movable magnet that is a magnet formed on at least one of the shaft members, and (4) facing at least one of the shaft members. And a fixed-side magnet, which is a magnet disposed on the fixed portion. When the galvanomirror rotates from a predetermined rotation position, the galvanomirror is urged in a direction to return to the predetermined rotation position by the action of the movable magnet and the fixed magnet.

With this configuration, it is possible to always hold the galvanomirror at a predetermined rotational position except when the galvanomirror is driven to rotate. Further, since it is not necessary to separately provide equipment for holding the galvanomirror at a predetermined rotation position, the number of parts does not increase.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, near field recording (NFR: near) has been proposed in response to a demand for an external storage device accompanying the progress of hardware and software related to a computer in recent years, particularly, a demand for a large storage capacity. field recordin
g) An outline of a magneto-optical disk recording / reproducing apparatus using a recording / reproducing method called a technique will be described with reference to FIGS.

FIG. 1 is an overall schematic diagram of the optical disk device. An optical disk 2 is mounted on a rotating shaft of a spindle motor (not shown) in the disk drive device 1. On the other hand, a rotating (coarse movement) arm 3 for reproducing or recording information on the optical disk 2 is mounted so as to be parallel to the recording surface of the optical disk 2. This rotating arm 3
Is rotatable about a rotation shaft 5 by a voice coil motor 4. A floating optical head 6 having an optical element mounted thereon is mounted on a tip of the rotating arm 3 facing the optical disk 2. In addition, the rotating arm 3
A light source module 7 having a light source unit and a light receiving unit is disposed in the vicinity of the rotation shaft 5 and is configured to be driven integrally with the rotating arm 3.

FIGS. 2 and 3 illustrate the tip of the rotating arm 3, and particularly describe the flying optical head 6 in detail. The floating optical unit 6 is attached to the flexure beam 8 and is arranged to face the optical disc 2. The flexure beam 8 is fixed to the rotating arm 3 at the other end, and presses the floating optical unit 6 at the distal end portion in a direction in which the floating optical unit 6 comes into contact with the optical disc 2 by the elastic force of the flexure beam 8.

The floating type optical unit 6 includes a floating slider 9, an objective lens 10, and a solid immersion lens (S
IL) 11 and a magnetic coil 12 and function to converge a parallel laser beam 13 emitted from the light source module 7 onto the optical disc 2. A rising mirror 31 is fixed to the tip of the rotating arm 3 to guide the laser beam 13 to the floating optical unit 6. The laser beam 13 incident on the objective lens 10 by the rising mirror 31 is converged by the refraction of the objective lens 10. A solid immersion lens (SIL) 11 is arranged in the vicinity of the converging point, and irradiates the convergent light to the optical disc 2 as finer evanescent light 15.

A magnetic coil 12 for recording by a magneto-optical recording method is formed around a solid immersion lens (SIL) 11 facing the optical disk 2. It can be applied on the surface. This evanescent light 1
5 and the magnetic coil 12 enable high-density recording and reproduction on the optical disk 2. The floating optical unit 6 floats by a very small amount due to the airflow generated by the rotation of the optical disk 2 and follows the surface runout of the optical disk 2. For this reason, focus control (focus servo) of the objective lens, which is required in the conventional optical disk device, is not required.

The light source module 7 mounted on the rotating arm 3 and the light beam guided to the floating optical unit 6 will be described below in detail with reference to FIGS. The rotating arm 3 has a floating type optical unit 6 mounted at the tip and a driving coil 1 for driving a voice coil motor 4 at the other end.
6 is fixed. The drive coil 16 is a flat coil, and is inserted and arranged in a magnetic circuit (not shown) with a gap. The rotating shaft 5 and the rotating arm 3 are provided with a bearing 17,
When the current is applied to the drive coil, the rotation arm 3 can be rotated about the rotation shaft 5 by the electromagnetic action with the magnetic circuit.

The light source module 7 mounted on the rotating arm 3 has a semiconductor laser 18, a laser drive circuit 19,
Collimating lens 20, composite prism assay 21, laser power monitor sensor 22, reflection prism 2
3, a data detection sensor 24 and a tracking detection sensor 25 are arranged. The laser beam in a divergent beam state emitted from the semiconductor laser 18 is converted into a parallel beam by the collimating lens 20. The cross-sectional shape of the parallel light beam is an elliptical shape due to the characteristics of the semiconductor laser 18, and it is inconvenient to narrow the light beam onto the optical disk 2 minutely. Therefore, the cross-sectional shape of the parallel light beam is shaped by making the parallel light beam having an elliptical cross section emitted from the collimating lens 20 enter the composite prism assay 21.

The entrance surface 21a of the composite prism assay 21
Has a predetermined slope with respect to the incident optical axis. By refracting the incident light, the cross-sectional shape of the parallel light beam can be shaped from an oval shape to a substantially circular shape. The shaped laser beam travels through the complex prism assay 21 and enters the first half mirror surface 21b. The first half mirror surface 21b transmits information obtained from the optical disk 2 to the data detection sensor 24 and the tracking detection sensor 25.
However, on the outward path, it serves to separate the light beam to the laser power monitor sensor 22 for detecting the output power of the laser emitted from the semiconductor laser 18.

Since the laser power monitor sensor 22 outputs a current proportional to the intensity of the received light, the output of the semiconductor laser 18 can be stabilized by feeding back this output to a laser power control circuit (not shown). . The laser beam 13 having a substantially circular cross section emitted from the composite prism assay 21 is irradiated on the galvanomirror 26, and the traveling direction of the laser beam 13 is changed. The galvanomirror 26 is rotated about an axis perpendicular to the plane of the paper, and can swing the laser beam 13 by a small angle in a direction parallel to the plane of the paper.

Behind the galvanometer mirror 26, a mirror position detection sensor 28 for detecting the rotation angle of the galvanometer mirror 26 is provided. The laser beam 13 reflected by the galvanomirror 26 passes through a first relay lens 29 and a second relay lens (imaging lens) 30, and is reflected by a rising mirror 31 before reaching the floating optical unit 6. The first relay lens 29 and the second relay lens 30 make the relationship between the reflection surface of the galvanometer mirror 26 and the pupil surface (principal plane) of the objective lens 10 arranged in the floating optical unit 6 into a conjugate relationship. That is, a relay lens optical system is formed. That is, when the focused beam on the optical disc 2 is slightly deviated from a predetermined track, the laser beam 13 incident on the objective lens 10 is tilted by slightly rotating the galvanometer mirror 26 to move the focal point on the optical disc 2. Correction. However, when the focus is corrected by this method, if the optical distance between the galvanomirror 26 and the objective lens 10 is long, the movement amount of the laser beam 13 incident on the objective lens 10 becomes large, and the incident light can be incident on the objective lens 10. May disappear.

In order to avoid such a phenomenon, the first relay lens 29 and the second relay lens 30
The relationship between the reflecting surface of the galvanomirror 26 and the pupil plane of the objective lens 10 is set to be a conjugate relationship. Even if the galvanomirror 26 rotates, the laser beam 13 incident on the objective lens 10 does not move, and Tracking control is made possible. The access operation over the inner circumference / outer circumference of the optical disc 2 is performed by rotating the rotating arm 3 by the voice coil motor 4 and only the minute tracking control is performed by rotating the galvanometer mirror 26.

The returning laser beam 13 reflected from the optical disk 2 returns in the reverse direction of the outward path and is reflected by the galvanomirror 26 to enter the composite prism assay 21. Thereafter, the light is reflected by the first half mirror surface 21b and travels to the second half mirror surface 21c. The second half mirror surface 21c generates transmitted light directed to the tracking detection sensor 25 and reflected light directed to the data detection sensor 24, and separates the laser beam on the return path. The laser beam transmitted through the second half mirror surface 21c is applied to the tracking detection sensor 25, and outputs a tracking error signal.

On the other hand, the laser beam reflected by the second half mirror surface 21c is polarized and separated by the Wollaston prism 32, converted into convergent light by the condenser lens 33, and then reflected by the reflection prism 23 to be detected by the data detection sensor. 24. The data detection sensor 24 has two light receiving areas, and receives two polarized beams polarized and separated by the Wollaston prism 32 to read data information recorded on the optical disk 2 and output a data signal. To be precise, the tracking error signal and the data signal are generated by a head amplifier circuit (not shown) and sent to a control circuit or an information processing circuit.

Next, a configuration for holding the galvanometer mirror 26 will be described. FIG. 6 shows a galvanomirror 26.
FIG. 7 is a perspective view showing a galvano mirror assembly 27 including the above. The galvanometer mirror 26 is fixed to the mirror holder 100 and rotates around a predetermined rotation axis (referred to as Z).
The mirror holder 100 is rotatably supported in the stator 150 about a rotation axis Z.

The mirror holder 100 is a barrel-shaped block, and its central axis (X axis) is orthogonal to the rotation axis Z. In FIG. 6, an axis orthogonal to both the X axis and the rotation axis Z is defined as a Y axis. The galvanometer mirror 26 is mounted on the mirror holder 1 such that the mirror surface 26a is orthogonal to the Y axis.
Attach to 00. Also, X of the mirror holder 100
At both ends in the axial direction, coils 101 and 102 are held, respectively.

A pair of magnets 191 and 192 are arranged on a later-described stator 150 (FIG. 7) so as to face the coils 101 and 102 of the mirror holder 100. When a current is applied to the coils 101 and 102, the coils 10 and
The mirror holder 100 is rotated about a rotation axis Z by the action of electromagnetic induction between the mirror holders 1 and 102 and the magnets 191 and 192. Thereby, the direction of the laser beam reflected by the galvanometer mirror 26 can be changed.

FIG. 7 is a side sectional view of the galvanomirror assembly 27. Conical center pins 122 and 124 are provided on the upper and lower surfaces of the mirror holder 100.
The stator 150 is provided with bearings 106 and 108 which are conical recesses for receiving the center pins 122 and 124. The center pins 122 and 124 are sandwiched between a pair of bearings 106 and 108 from both sides in the vertical direction in the figure. Have been.

The bearings 106 and 108 are substantially conical recesses, and the center pins 122 and 124 are substantially conical pins having spherical tips. Center pins 122, 12
The spherical part at the tip of No. 4 is in contact. The galvanomirror 26 is supported by the pair of center pins 122 and 124 and the bearings 106 and 108 so as to be rotatable about a predetermined rotation axis (referred to as the Z axis). The galvanomirror 26
Is an axis whose mirror surface 26a is perpendicular to the rotation axis Z (Y
(Referred to as an axis) is attached to the mirror holder 100.

Of the pair of bearings 106, 108, the upper bearing 106 is fixed to the lower surface of a leaf spring 130 attached to the stator 150. The lower bearing portion 108 is press-fitted and fixed to the stator 150. That is,
The bearings 106 and 108 are configured to apply pressure in the thrust direction with the center pins 122 and 124 sandwiched from above and below. The ring-shaped magnet 1 is attached to the stator 150 so as to surround the lower center pin 124.
40 are provided.

FIG. 8 is a perspective view showing the center pin 124 and the ring magnet 140 separately. Center pin 12
Reference numeral 4 denotes a permanent magnet, which is divided into two sections with a surface 124a including the central axis thereof interposed therebetween, and is magnetized to the N pole and the S pole, respectively. Surface 1 which is the boundary between the two poles
At 24a (neutral plane), the magnetic field is zero.

The ring-shaped magnet 140 is composed of two magnets (half-ring magnets 141 and 14) having a semi-circular cross section.
2) is joined at the end face. One half ring magnet 141 is magnetized with an N pole on the outer periphery and an S pole on the inner periphery, and the other half ring magnet 142 is magnetized on the S pole on the outer periphery and N pole on the inner periphery. Two half ring magnets 141,
The magnetic field is zero on a surface 145 (neutral surface) including the junction surface 142.

FIGS. 9A and 9B show the lower center pin 1.
It is the top view and side sectional drawing which show the state which combined 24 and the ring-shaped magnet 140. As shown in FIG. 9B, the center pin 124 passes through the inside of the ring-shaped magnet 140 fixed to the stator 150 (FIG. 7). The center pin 124 is supported by the above-described bearing portion 108 (FIG. 7) so as to be rotatable around its central axis.

As shown in FIG. 9A, the center pin 124 and the ring magnet 140 exert repulsive and attractive forces on each other, but the neutral surface 124a of the center pin 124 and the neutral surface 145 of the ring magnet 140.
Balance on the same plane. At this time, the N pole portion of the center pin 124 faces the S pole portion inside the half ring magnet 141, and the S pole portion of the center pin 124 faces the N pole portion inside the half ring magnet 142.

When the center pin 124 rotates clockwise from the neutral state shown in FIG.
And the N pole portion inside the half-ring magnet 142 partially opposes to generate a repulsive force. Similarly, the center pin 12
The S pole portion 4 and the S pole portion inside the half ring magnet 142 partially oppose each other to generate a repulsive force. These repulsive forces serve as urging forces for returning the center pin 124 to the neutral state. Similar biasing force is generated when the center pin 124 rotates counterclockwise.

With this configuration, if the position of the galvanometer mirror 26 when the center pin 124 is in the neutral state shown in FIG. 9A is set as the neutral position of the galvanometer mirror 26, The galvanomirror 26 can always be held at the neutral position except during the rotation drive (when current is flowing through the coils 101 and 102).

Next, a second embodiment of the present invention will be described. FIG. 10 is a perspective view showing a center pin 224 and a ring magnet 240 according to the second embodiment. The center pin 224 is divided into four sections by two planes including the central axis and orthogonal to each other, and are magnetized into N, S, N, and S poles, respectively.

The ring-shaped magnet 240 has four magnets 241, 242, 243 and an arc-shaped cross section having an inner angle of 90 °.
244 are joined in a ring shape. Magnet 241,
The inner peripheral surfaces of 242, 243, 244 have S pole, N pole, S pole,
Each is magnetized to the N pole, and the outer peripheral surface is magnetized to a polarity opposite to that of the inner peripheral surface.

FIG. 11 is a top view and a side sectional view showing a state where the center pin 224 and the ring magnet 240 are combined. The center pin 224 and the ring-shaped magnet 240 exert repulsive and attractive forces on each other, but are balanced in a state where the neutral surface 224a of the center pin 224 and the neutral surface 245 of the ring-shaped magnet 240 are located on the same surface. At this time, the N pole portion of the center pin 224 faces the S pole portion inside the half ring magnets 241, 243, and the S pole portion of the center pin 224 is the half ring magnets 242, 244.
Is opposed to the N-pole portion inside.

With this configuration, the second
According to the embodiment, similarly to the first embodiment, (except when the galvanomirror 26 is driven to rotate), the galvanomirror 2
6 can always be held in the neutral position.

[0036]

As described above, according to the galvanomirror holding structure of the present invention, it is possible to hold the galvanomirror at a predetermined rotational position except when the galvanomirror is driven to rotate. Can be

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a basic configuration of a magneto-optical disk device according to an embodiment.

FIG. 2 is a diagram showing a distal end portion of a rotating arm.

FIG. 3 is a cross-sectional view showing a floating optical unit.

FIG. 4 is a plan view showing an internal configuration of a rotating arm.

FIG. 5 is a side sectional view of a rotating arm.

FIG. 6 is a perspective view showing a galvano mirror assembly according to the first embodiment.

FIG. 7 is a side sectional view showing the galvanomirror assembly of FIG. 6;

FIG. 8 is a perspective view showing a center pin and a ring-type magnet of FIG. 6;

FIG. 9 is a cross-sectional view showing the center pin and the ring-shaped magnet of FIG. 6;

FIG. 10 is a perspective view illustrating a galvanomirror assembly according to a second embodiment.

FIG. 11 is a perspective view showing a center pin and a ring-type magnet of FIG. 10;

[Explanation of symbols]

 26 Galvano mirror 27 Galvano mirror assembly 100 Mirror holder 106, 108 Bearing part 122, 124 Center pin 140 Ring magnet 150 Stator 224 Center pin 240 Ring magnet

Claims (6)

[Claims] A movable part to which a galvanomirror is fixed;
A fixed part that holds the movable part rotatably about a predetermined rotation axis. A galvanomirror assembly, wherein the movable part is provided at a position corresponding to the rotation axis of the movable part.
Two shaft members, two bearings provided on the fixed portion and receiving the two shaft members, respectively, a movable magnet that is a magnet formed on at least one of the shaft members, and the at least one shaft member And a fixed-side magnet, which is a magnet disposed on the fixed portion so as to face with, when the galvanomirror is rotated from a predetermined rotation position, by the action of the movable-side magnet and the fixed-side magnet. ,
A galvanomirror holding structure, wherein the galvanomirror is biased in a direction to return to the predetermined rotational position. 2. The galvanomirror holding structure according to claim 1, wherein the fixed magnet is formed in a ring shape surrounding the shaft member. 3. The fixed magnet according to claim 1, wherein an inner peripheral surface of the fixed magnet includes a portion having the same polarity as that of the movable magnet.
Or the holding structure of the galvanometer mirror according to 2. 4. The shaft member according to claim 1, wherein an outer peripheral surface of the shaft member is divided into a plurality of sections, and the plurality of sections include a portion magnetized to an N pole and a portion magnetized to an S pole. 4. The galvanomirror holding structure according to any one of items 1 to 3. 5. The fixed-side magnet is formed by combining a plurality of magnets having an arc-shaped cross section in a ring shape, wherein the plurality of arc-shaped magnets are magnetized to have an S pole on the inner circumference and an N pole on the outer circumference. 5. The magnetic recording medium according to claim 1, further comprising a magnetic material having an inner peripheral side magnetized to an N pole and an outer peripheral side magnetized to an S pole.
The galvanomirror holding structure according to any one of the above. 6. The galvanomirror holding structure according to claim 1, wherein a tip of said shaft member has a predetermined spherical shape.