JP3510775B2 - Galvano mirror - 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, and more particularly to a galvanometer mirror suitable for use in fine movement tracking of an optical information recording / reproducing apparatus.

[0002]

Recently, the areal recording density is 1
Development of magneto-optical disk devices exceeding 0 Gbit / (inch) ² is in progress. In this device, the angle of incidence of the laser beam with respect to the objective optical system provided at the tip of the coarse movement arm that rotates, for example, in the direction intersecting with the track of the magneto-optical disk is finely adjusted by a deflecting means such as a galvanometer mirror to perform fine movement It is considered that the tracking is accurately performed at a track pitch level as narrow as 0.34 μm. By the way, as a galvanomirror usually used for such a coarse movement arm, there is a pivot support type.
In this system, the play of the shaft support of the movable part causes play, which causes a problem of unnecessary change in posture of the movable part.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the background as described above, and the invention of claim 1 is characterized in that a movable portion having a deflection mirror attached by electromagnetic drive is centered around a rotary shaft. A galvano-mirror for rotating the movable part in a predetermined angle range, wherein the rotary shaft of the movable part receives two center pins provided on the fixed side with the movable part in between, and the movable pin that receives the respective tip parts of these center pins. And a bush so that one of the center pins is slidable in the axial direction and the end of the center pin opposite to the side in contact with the bearing projects. At least one end of the center pin protruding from the bush is axially pressed by a pressurizing spring attached to the housing side. Made of a conductive material, a partial arc surface of the inner peripheral surface of the bush is constituted by a magnet, and the one center pin is magnetically brought into contact with the partial arc surface in the bush to form the bush and the bush. It is characterized in that the play between the center pins is absorbed.

According to a second aspect of the present invention, there is provided a galvano-mirror for electromagnetically driving a movable part having a deflecting mirror attached thereto, the movable part being rotated about a rotation axis within a predetermined angle range. And a pair of center pins provided on both sides of the movable part, and two bearings provided on the side of the movable part that respectively receive the tip ends of these center pins, and one of the center pins slides in the axial direction. The center pin is movably attached to the bush so that the end of the center pin opposite to the side in contact with the bearing projects, and at least one end of the center pin projecting from the bush is attached to the housing. The one center pin is formed of a permanent magnet whose polarity is changed with the axial cross section as a boundary, and the bush of the bush is formed. Part of the peripheral surfaces facing each other are magnetic pole surfaces of the same polarity, and the one center pin is magnetically brought into contact with the one peripheral surface in the bush so that the bush and the one center. The feature is that the play between the pins is absorbed.

[0005]

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. Objective lens 1 by the raising mirror 31
The laser light flux 13 incident on 0 is converged by the refraction of the objective lens 10. A solid immersion lens (SIL) 11 is arranged near this condensing point,
The converged light is applied to the optical disc 2 as finer evanescent light 15.

A magnetic coil 12 for recording by the magneto-optical recording system is formed around the solid immersion lens (SIL) 11 facing the optical disc 2, and a magnetic field required 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 light flux 13 having a substantially circular cross-sectional shape emitted from the composite prism assay 21 is irradiated on the deflection mirror 26, and the traveling direction of the laser light flux 13 is changed. The deflecting mirror 26 is attached to a galvanomotor 27 whose center of rotation is an axis perpendicular to the plane of the paper, and is capable of swinging the laser beam 13 by a small angle in a direction parallel to the plane of the paper.

Further, the galvano motor 27 is provided with a deflection mirror position detection sensor 28 for detecting the rotation angle of the deflection mirror 26. The laser light flux 13 reflected by the deflection mirror 26 is reflected by the first relay lens 29 and the second relay lens 29.
After passing through the relay lens (imaging lens) 30 of FIG. The first relay lens 29 and the second relay lens 30 make the relationship between the reflecting surface of the deflection mirror 26 and the pupil surface (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 focused beam on the optical disc 2 is slightly deviated from a predetermined track, the deflection mirror 26 is slightly rotated to tilt the laser beam 13 incident on the objective lens 10 to move the focus on the optical disc 2. To correct it. However, when correcting the focus with this method,
When the optical distance between the deflection mirror 26 and the objective lens 10 is long, the amount of movement of the laser light flux 13 incident on the objective lens 10 becomes large, and it may not be possible to enter the objective lens 10.

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 deflecting mirror 26 and the pupil plane of the objective lens 10 is set to be a conjugate relationship, and even if the deflecting mirror 26 rotates, the laser light flux 13 incident on the objective lens 10 does not move, so It is possible to perform various tracking controls. The access operation across the inner and outer circumferences of the optical disk 2 is performed by rotating the rotating arm 3 by the voice coil motor 4 and rotating the deflecting mirror 26 only for minute tracking control.

The returning laser beam 13 reflected from the optical disk 2 travels in the opposite direction to the going path and the deflection mirror 2
It is reflected by 6 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 rotating the deflection mirror 26 in the above-described galvano motor 27 will be described. FIG. 6 is a cross-sectional view showing a galvano motor 27 (a unit including the deflection mirror 26: a so-called galvano mirror). The deflection mirror 26 is held by the mirror holder 100, and the mirror holder 100 is fixed to the stator 150.
It is housed inside. It should be noted that the description of the coil and the magnet for rotationally driving the deflection mirror 26 is omitted.

The mirror holder 100 is sandwiched by a pair of center pins 122 and 124 attached to the stator 150 from both sides in the vertical direction in the figure. A pair of center pins 122, 1 are provided on the upper and lower surfaces of the mirror holder 100.
Bearing portions 106 and 108, which are conical holes for receiving 24, are formed. The deflection mirror 26 is rotatably supported by a pair of center pins 122 and 124 and the bearings 106 and 108 about a predetermined rotation axis (Z axis). The deflecting mirror 26 has a mirror surface 26a
It is attached to the mirror holder 100 so as to be orthogonal to the axis (Y axis) orthogonal to the rotation axis Z.

Of the pair of center pins 122 and 124, the lower center pin 124 is press-fitted and fixed to the stator 150. On the other hand, the upper center pin 12
Reference numeral 2 is attached to the stator 150 in a state of being inserted into a bush 130 having a flange shape. The upper center pin 122 is held in the bush 130 so as to be slidable up and down, and is biased downward by a pressurizing spring 160 from above. A permanent magnet 140 (described later) is fitted inside the bush 130.

FIG. 7 is a perspective view and a side sectional view showing the upper center pin 122 and the permanent magnet 140. The upper center pin 122 is made of a ferromagnetic material, specifically, ferromagnetic stainless steel. The permanent magnet 140 has an arc shape and is arranged on one side of the center axis of the upper center pin 122. Further, the permanent magnet 140 is magnetized in the radial direction (for example, the inside is the S pole and the outside is the N pole).

FIG. 8 is a side sectional view showing the upper center pin 122 and the permanent magnet 140. Upper center pin 12
Since No. 2 is attracted to the permanent magnet 140 provided on one side, the upper center pin 122 can always be inclined to the permanent magnet 140 side even if there is a clearance between the bush 130 and the upper center pin 122. it can. That is, the deflection mirror 2 that accompanies a change in the tilt direction of the mirror holder 100.
It is possible to prevent unnecessary posture change of No. 6.

FIG. 9 is a side sectional view showing a galvano motor according to the second embodiment. In the second embodiment, the upper center pin 122 is made of a permanent magnet, and two permanent magnets 240 and 250 are provided inside the bush 130. 10 and 11 are a perspective view and a sectional view showing the upper center pin 122 and the permanent magnets 240 and 250.
The upper center pin 122 is magnetized into an N pole and an S pole with a predetermined cross section 122a including the central axis as a boundary. Figure 10
As shown in FIG. 5, the permanent magnets 240 and 250 have an arc shape, and are arranged so as to face the north pole and the south pole of the upper center pin 122, respectively.

FIG. 10 is a side sectional view showing the upper center pin 122 and the permanent magnets 240 and 250. The upper center pin 122 is repelled by the permanent magnet 250 on the right side of the drawing and is attracted to the permanent magnet 240 on the left side of the drawing. Therefore,
The mirror holder 100 can be surely tilted to the permanent magnet 240 side. That is, according to the second embodiment, it is possible to more reliably prevent an unnecessary posture change of the deflection mirror 26.

[0025]

As described above, according to the galvano mirror of the present invention, it is possible to prevent an unnecessary posture change due to a change in the tilt direction of the movable part.

[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 a deflection mirror and a floating optical unit.

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

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

7 is a perspective view showing an upper center pin and a permanent magnet of FIG.

8 is a cross-sectional view showing an upper center pin and a permanent magnet of FIG.

FIG. 9 is a perspective view showing a galvano motor according to a second embodiment.

10 is a perspective view showing the upper center pin and the permanent magnet of FIG. 9. FIG.

11 is a cross-sectional view showing an upper center pin and a permanent magnet of FIG.

[Explanation of symbols]

26 Deflection mirror 27 Galvo Motor 100 mirror holder 106, 108 bearing 122,124 Center pin 130 bush 140 permanent magnet 150 stator 160 chips

Claims (2)

(57) [Claims] 1. A galvano-mirror for electromagnetically driving a movable part having a deflection mirror mounted thereon to rotate about a rotary shaft within a predetermined angle range, wherein the rotary shaft of the movable part is sandwiched on the fixed side. The center pin is configured by two provided center pins and two bearings provided on the side of the movable part that respectively receives the tip ends of these center pins, and one of the center pins is slidable in the axial direction The pin is attached to a bush so that the end opposite to the side in contact with the bearing protrudes, and the end of the center pin protruding from this bush is pressed in the axial direction by a pressure spring attached to at least one end on the housing side. In addition, the one center pin is formed of a ferromagnetic material, and the partial arc surface of the inner peripheral surface of the bush is formed of a magnet,
A galvanometer mirror characterized in that the one center pin is magnetically brought into contact with the partial arc surface in the bush so as to absorb the play between the bush and the one center pin. 2. A galvano-mirror for electromagnetically driving a movable part having a deflection mirror mounted thereon, the movable part being rotated around a rotation axis within a predetermined angle range, wherein the rotation axis of the movable part is sandwiched between the movable part and the movable part. The center pin is configured by two provided center pins and two bearings provided on the side of the movable part that respectively receives the tip ends of these center pins, and one of the center pins is slidable in the axial direction The pin is attached to a bush so that the end opposite to the side in contact with the bearing protrudes, and the end of the center pin protruding from this bush is pressed in the axial direction by a pressure spring attached to at least one end on the housing side. Further, the one center pin is formed of a permanent magnet whose polarity is changed with the axial cross section as a boundary, and one of the inner peripheral surfaces of the bush opposite to each other is formed. Each part is composed of magnetic pole faces of the same polarity,
A galvanometer mirror characterized in that the one center pin is brought into contact with the one circumferential surface in the bush by a magnetic force so as to absorb the play between the bush and the one center pin.