JP3510789B2 - Galvano mirror holding structure - Google Patents

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 in an optical disk device or the like.

[0002]

Recently, the areal recording density is 1
Development of optical disk devices exceeding 0 Gbit / (inch) ² is progressing. In such an optical disc apparatus, in order to perform tracking with high accuracy, a galvanometer mirror, which is a deflection unit, is provided between the light source and the objective optical system facing the recording surface of the optical disc. By rotating this galvanometer mirror, the incident angle of the light beam to the objective optical system is slightly changed, and the light spot is finely moved on the recording surface of the optical disc.

Generally, a pivot system is adopted as a structure for rotatably supporting the galvanometer mirror. However, in this method, the galvanometer mirror is freely rotated, so that it is necessary to separately provide some kind of equipment for holding the galvanometer mirror at a predetermined rotation position.

The present invention has been made in view of the above background, and it is an object of the present invention to provide a holding structure for a galvano mirror capable of holding the galvano mirror at a predetermined rotational position. .

[0005]

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

According to this structure, the galvano mirror can always be held at a predetermined rotational position except when the galvano mirror is rotationally driven. Further, since it is not necessary to separately provide equipment for holding the galvano mirror at a predetermined rotation position, the number of parts does not increase.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION First, near field recording (NFR: near field recording) has been proposed in response to a demand for an external storage device, especially a demand for a large storage capacity, accompanying the progress of hardware and software in recent years. field recordin
g) An outline of a magneto-optical disk recording / reproducing apparatus using a recording / reproducing system called technology will be described with reference to FIGS. 1 to 5.

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

FIGS. 2 and 3 explain the tip of the rotary arm 3, and particularly the floating optical head 6 in detail. The floating optical unit 6 is attached to the flexure beam 8 and is arranged so as to face the optical disc 2. Further, the flexure beam 8 is fixed to the rotating arm 3 at the other end, and the elastic force of the flexure beam 8 presses the levitation optical unit 6 at the tip end in a direction of contacting the optical disc 2.

The levitation type optical unit 6 comprises a levitation slider 9, an objective lens 10 and a solid immersion lens (S).
IL) 11 and a magnetic coil 12 and serves to converge the parallel laser light flux 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 for guiding the laser beam 13 to the floating optical unit 6. The laser light flux 13 incident on the objective lens 10 by the raising mirror 31 is converged by the refraction of the objective lens 10. A solid immersion lens (SIL) 11 is arranged in the vicinity of this condensing point, and the converged light is irradiated onto the optical disc 2 as finer evanescent light 15.

Further, a magnetic coil 12 for recording by a magneto-optical recording system is formed around a solid immersion lens (SIL) 11 facing the optical disc 2, and a magnetic field necessary for recording is recorded on the optical disc 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 disc 2. The levitation type optical unit 6 floats a small amount by the air flow caused by the rotation of the optical disc 2, and follows the surface runout of the optical disc 2. Therefore, the focus control (focus servo) of the objective lens, which is required in the conventional optical disk device, is unnecessary.

The light beam guided to the light source module 7 and the floating optical unit 6 mounted on the rotating arm 3 will be described in detail below with reference to FIGS. 4 and 5. The rotating arm 3 has a floating optical unit 6 mounted at its tip and a drive 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 have bearings 17,
It is rotatably fastened by 17, and when a current is applied to the drive coil, the rotating arm 3 can be rotated around the rotating shaft 5 by the electromagnetic action with the magnetic circuit.

The light source module 7 mounted on the rotating arm 3 includes a semiconductor laser 18, a laser drive circuit 19,
Collimating lens 20, compound prism assay 21, laser power monitor sensor 22, reflecting prism 2
3, a data detection sensor 24, and a tracking detection sensor 25 are arranged. The laser light flux in a divergent light flux state emitted from the semiconductor laser 18 is converted into a parallel light flux by the collimator lens 20. Due to the characteristics of the semiconductor laser 18, the cross-sectional shape of this parallel light flux is elliptical, and it is inconvenient to minutely narrow the light beam onto the optical disc 2, so it is necessary to convert it into a substantially circular cross section. Therefore, the cross-sectional shape of the parallel light flux is shaped by causing the parallel light flux having an elliptical cross-section emitted from the collimator lens 20 to enter the composite prism assay 21.

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

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-sectional shape emitted from the composite prism assay 21 is applied to the galvanometer mirror 26, and the traveling direction of the laser beam 13 is changed. The galvanometer mirror 26 is rotated about an axis perpendicular to the paper surface, and the laser beam 13 can be swung by a minute angle in a direction parallel to the paper surface.

A mirror position detecting sensor 28 for detecting the rotation angle of the galvano mirror 26 is arranged behind the galvano mirror 26. The laser light flux 13 reflected by the galvanometer mirror 26 passes through the first relay lens 29 and the second relay lens (imaging lens) 30, and then reaches the levitation type optical unit 6 after being reflected by the rising mirror 31. The first relay lens 29 and the second relay lens 30 make the relationship between the reflecting surface of the galvanometer mirror 26 and the pupil plane (main plane) of the objective lens 10 arranged in the levitation type optical unit 6 into a conjugate relationship. In this way, the relay lens optical system is formed. That is, when the condensed 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 focus on the optical disc 2. To correct it. However, when the focal point is corrected by this method, if the optical distance between the galvanometer mirror 26 and the objective lens 10 is long, the amount of movement of the laser light flux 13 entering the objective lens 10 becomes large and the laser beam 13 can enter the objective lens 10. It may disappear.

In order to avoid such a phenomenon, by the first relay lens 29 and the second relay lens 30,
The relationship between the reflecting surface of the galvano mirror 26 and the pupil plane of the objective lens 10 is set to be a conjugate relationship, and even if the galvano mirror 26 rotates, the laser light flux 13 incident on the objective lens 10 does not move, and thus the laser beam 13 is accurate. It is possible to perform various tracking controls. The access operation across the inner circumference / outer circumference of the optical disk 2 is performed by rotating the rotating arm 3 by the voice coil motor 4, and only minute tracking control is performed by rotating the galvano mirror 26.

The returning laser beam 13 reflected from the optical disk 2 travels in the opposite direction to the outward path, is reflected by the galvano mirror 26, and enters the composite prism assay 21. After that, the light is reflected by the first half mirror surface 21b and heads for the second half mirror surface 21c. The second half mirror surface 21c generates a transmitted light toward the tracking detection sensor 25 and a reflected light toward the data detection sensor 24, and separates the return laser light flux. The laser light flux that has passed 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 light flux 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 is irradiated. The data detection sensor 24 has two light receiving regions, and receives the two polarized beams that are polarized and separated by the Wollaston prism 32, thereby reading the data information recorded on the optical disc 2 and outputting the 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 the control circuit or the information processing circuit.

Next, the structure for holding the galvano mirror 26 will be described. FIG. 6 shows a galvanometer mirror 26.
It is a perspective view which shows the galvano mirror assembly 27 containing. The galvano mirror 26 is fixed to the mirror holder 100 and rotates about a predetermined rotation axis (denoted by Z).
The mirror holder 100 is supported in the stator 150 so as to be rotatable about the 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, the axis orthogonal to both the X axis and the rotation axis Z is the Y axis. The galvano mirror 26 has the mirror holder 1 so that its mirror surface 26a is orthogonal to the Y axis.
It is attached to 00. In addition, X of the mirror holder 100
Coils 101 and 102 are respectively held at both ends in the axial direction.

A pair of magnets 191 and 192 are arranged on a stator 150 (FIG. 7) described later 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 coil 10
1, 102 and the magnets 191, 192 cause the mirror holder 100 to rotate about the rotation axis Z by the action of electromagnetic induction. 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 galvanometer mirror assembly 27. Conical center pins 122 and 124 are provided on the upper and lower surfaces of the mirror holder 100.
Further, the stator 150 is provided with bearing portions 106 and 108 which are conical recesses for receiving the center pins 122 and 124, and the center pins 122 and 124 are sandwiched by the pair of bearing portions 106 and 108 from both sides in the vertical direction in the figure. Has been.

The bearings 106 and 108 are substantially conical recesses, and the center pins 122 and 124 are substantially conical pins having a spherical tip. The center pins 122, 12 are formed on the inner surfaces of the substantially conical recesses of the bearings 106, 108.
The spherical portion at the tip of 4 is in contact. The pair of center pins 122 and 124 and the bearing portions 106 and 108 support the galvano mirror 26 so as to be rotatable around a predetermined rotation axis (Z axis). The galvanometer mirror 26
Has a mirror surface 26a whose axis (Y
It is attached to the mirror holder 100 so as to be orthogonal to the (axis).

Of the pair of bearings 106, 108, the upper bearing 106 is fixed to the lower surface of the leaf spring 130 attached to the stator 150. Further, 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 is 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 interposed therebetween, and is magnetized to each of an N pole and an S pole. Surface 1 which is the boundary surface of both poles
At 24a (neutral plane), the magnetic field is zero.

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

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

As shown in FIG. 9A, the center pin 124 and the ring-shaped magnet 140 exert repulsive and attractive forces on each other, but the neutral surface 124 a of the center pin 124 and the neutral surface 145 of the ring-shaped magnet 140.
Balance when is located 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 is rotated clockwise from the neutral state shown in FIG. 9A, the center pin 124 is rotated.
Part of the N pole part and the N pole part inside the half ring magnet 142 face each other to generate a repulsive force. Similarly, the center pin 12
The S-pole portion of No. 4 and the S-pole portion inside the half ring magnet 142 partially face each other to generate a repulsive force. These repulsive forces serve as a biasing force for returning the center pin 124 to the neutral state. Similar urging force is generated when the center pin 124 rotates counterclockwise.

Due to this configuration, if the position of the galvano mirror 26 when the center pin 124 is in the neutral state shown in FIG. 9A is set as the neutral position of the galvano mirror 26, The galvano-mirror 26 can be kept in the neutral position at all times except when it is rotationally driven (when a current is applied to the coils 101 and 102).

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

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

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

Because of this structure, the second
According to the second embodiment, the galvano mirror 2 (except when the galvano mirror 26 is rotationally driven) is used as in the first embodiment.
6 can always be held in the neutral position.

[0036]

As described above, according to the holding structure of the galvano mirror of the present invention, it is possible to hold the galvano mirror at a predetermined rotational position except when the galvano mirror is rotationally driven. To be

[Brief description of drawings]

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

FIG. 2 is a diagram showing a tip portion of a rotating arm.

FIG. 3 is a cross-sectional view showing a floating type 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 the galvanometer mirror assembly according to the first embodiment.

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

FIG. 8 is a perspective view showing the center pin and the ring magnet of FIG.

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

FIG. 10 is a perspective view showing a galvanometer mirror assembly according to a second embodiment.

11 is a perspective view showing the center pin and the ring magnet of FIG.

[Explanation of symbols]

26 Galvo Mirror 27 Galvo mirror assembly 100 mirror holder 106, 108 bearing 122,124 Center pin 140 ring magnet 150 stator 224 Center pin 240 ring magnet

Claims (6)

(57) [Claims] 1. A movable part to which a galvano mirror is fixed,
A fixed part that holds the movable part rotatably around a predetermined rotation axis, and a galvanomirror assembly that is provided at a position corresponding to the rotation axis of the movable part.
One shaft member, two bearings provided in the fixed portion and respectively receiving the two shaft members, a movable magnet that is a magnet formed in at least one of the shaft members, and the at least one shaft member And a fixed-side magnet that is a magnet disposed in the fixed portion so as to face the fixed-side magnet, and when the galvano-mirror rotates from a predetermined rotation position, the movable-side magnet and the fixed-side magnet cause an action. ,
The holding structure for the galvano mirror, wherein the galvano mirror is biased in a direction to return to the predetermined rotation position. 2. The holding structure for a galvano mirror according to claim 1, wherein the fixed-side magnet is formed in a ring shape surrounding the shaft member. 3. The inner peripheral surface of the fixed-side magnet includes a portion having the same polarity as that of the movable-side magnet.
Alternatively, the holding structure of the galvano mirror according to the item 2. 4. The 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. The holding structure for the galvano mirror according to any one of 1 to 3. 5. The fixed-side magnet is a combination of a plurality of magnets having an arc-shaped cross section in a ring shape, and the plurality of arc-shaped magnets are magnetized to have an S pole on the inner peripheral side and an N pole on the outer peripheral side. And a magnetized body having an N-pole on the inner peripheral side and an S-pole on the outer peripheral side.
The holding structure for the galvano mirror according to any one of 1. 6. The holding structure for a galvano mirror according to claim 1, wherein the tip of the shaft member has a predetermined spherical shape.