JPH1114933A - Galvanometer mirror and optical disk device using the mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin optical disk device which can stably be controlled with simple constitution and has sufficient rigidity against an external force applied by the galvanometer mirror. SOLUTION: The galvanometer mirror 9A has a fixation part 22 around a swing part 23 having a reflecting mirror on its surface, two arbitrary opposite points at the outer periphery of the swing part 23 are suspended and supported on the fixation part 22 by a couple of elastic parts 25a and 25b, and on the reverse surface of the swing part 23, a projection part 26 is formed successively to the elastic parts 25a and 25b. On either of the reverse surface of the swing part 23 and the surface 37 facing it, a recessed part 34 may be formed including a part at least crossing the straight line connecting the elastic members 25a and 25b. Further, HOE(holographic optical element) 56 may be formed instead of a reflecting mirror on the top surface of the swing part 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvanomirror for reflecting a laser beam in a predetermined direction and an optical disk device using the same.

[0002]

2. Description of the Related Art In recent years, optical disk devices, such as a compact disk (CD) and a laser disk (LD), for recording and reproducing information using a laser beam, have become widespread. Recently, this optical disk device has been used as an external recording device of a computer. With the widespread use of such optical disk devices, there has been a demand for a technique capable of driving an optical head equipped with an optical system at a high speed so that information can be recorded and reproduced at a high speed.

In response to the demand for high-speed movement of the optical head,
A method has been proposed in which a galvanomirror that changes the direction of light is formed of silicon to reduce the size, and is mounted on an optical head to reduce the mass of the optical head as much as possible to realize a quick seek.

An example of the galvanometer mirror and an optical disk apparatus using the same will be described below with reference to FIGS. 13 to 17, X, Y, and Z axes are additionally shown in the drawings for convenience of description.

In FIG. 13, a disc 1 used for recording and reproducing information is held by a chucking means such as a magnet chuck on a spindle motor 2 fixed to a base (not shown). 2 stably drives. In the present specification, the disk 1 refers to all disk-shaped information recording media on which information is recorded and reproduced using a light spot, such as an optical disk or a magneto-optical disk.

A semiconductor laser 3 for generating a laser beam for irradiating the disk 1 has a structure as shown in FIG.
The photodetector 4 and the hologram optical element (hereinafter, HO)
An optical unit 6 is configured together with E-Holographic Optical Element 5). Optical unit 6
Is fixed to the lower part of the optical head 7 as shown in FIG. Note that a plurality of irregularities 6a are formed on the bottom surface of the optical unit 6 for the purpose of enhancing heat dissipation.

[0007] The laser light emitted from the semiconductor laser 3 passes through the HOE 5 formed on the glass surface, and
After the orientation is changed by 90 ° by the prism 8 fixed to the opposite surface of the optical head 7, the orientation is changed again by 90 ° by the galvanomirror 9 and guided to the objective lens 10 arranged above the optical head 7.
Then, the laser beam is focused on the recording track of the disk 1 by the objective lens 10 to form a focal point.

The reflected light from the disk 1 returns to the objective lens 10, passes through the galvanomirror 9 and the prism 8, and changes its direction by the HOE 5 as shown in FIG. A recording information signal, a focus offset signal, a track offset signal, and the like are generated from the reflected light captured by the photodetector 4. Then, by using the focus offset signal, the positional deviation of the objective lens 10 in the focus direction is detected,
A control operation for supplying a current to the focus coil 11 is performed so as to correct the positional deviation. Further, a position shift of the objective lens 10 in the track direction is detected by using the track offset signal, and a control operation is performed by applying a voltage to the linear motor coil 12 and the galvanometer mirror 9 so as to correct the position shift. In this way, information is recorded on the recording track of the disk 1, and the information is read from the recording track of the disk 1.

The objective lens 10 is, as shown in FIG.
It is held by an objective lens holder 13 formed of a plastic magnet. Further, one end of the parallel leaf spring 14 is fixed to the objective lens holder 13 and the other end of the parallel leaf spring 14 is fixed to the optical head 7, so that the objective lens 10 is supported so as to be movable in the optical axis direction. I have. An objective lens holder 13 made of a plastic magnet,
Electromagnetic action acts on the current flowing through the focus coil 11 fixedly wound around the optical head 7 and the objective lens 10
To generate a focus driving force.

The linear motor coil 12 is formed in a cylindrical shape, and one linear motor coil is fixed to each side surface of the optical head 7. A total of four sliding bearings 15 are formed on both sides of the linear motor coil 12 of the optical head 7. As shown in FIGS. 14 and 15, the sliding bearing 15 is engaged with two guide shafts 16 extending in the radial direction (X-axis direction) of the disk 1, respectively. Thus, the optical head 7 is supported so as to be movable in the radial direction of the disk 1.

The guide shaft 16 is made of a magnetic material, and also serves as a yoke for a magnetic circuit.
As shown in FIG. 14, U-shaped back yokes 17 are fixed to both ends of the guide shaft 16. A radial magnet 18 is disposed at a position facing the linear motor coil 12 with the magnetic gap therebetween, and a back yoke 17 is provided.
It is fixed to. These guide shaft 16, back yoke 17 and radial magnet 18 form a radial magnetic circuit 19.
Is formed, and a magnetic field is applied to the linear motor coil 12 to generate a driving force in the radial direction of the disk 1 on the optical head 7 by an electromagnetic action with a current flowing through the linear motor coil 12.

In the above configuration, the configuration of a conventional galvanometer mirror 90 will be described with reference to FIG. In FIG. 17, the galvanomirror 90 is the first plate 9
1, a second plate 96 and a third plate 98 are joined. The first plate 91 includes a frame member 92
A oscillating portion 94 made of a semiconductor such as silicon is connected via a pair of elastic portions 93 to each other, and a reflecting mirror 95 is formed on the oscillating portion 94.

Above and below the first plate 91, second and third plates 96 and 98 are respectively joined in an electrically insulated state. Second and third plates 96, 98
The electrodes 97a and 97b and the electrodes 99a and 99b are provided at respective positions opposed to the swinging portion 94 of each of them. In such a configuration, the swing portion 94 is charged to the positive (or negative) pole, the electrodes 97b and 99a are charged to the negative (or positive) pole, and the electrodes 97a and 99b are charged to the positive (or negative) pole. Then, the swinging portion 94 is rotated (swinged) with the torsional deformation of the pair of elastic portions 93.

Inside the optical head 7, a galvanomirror 9
Is arranged between the semiconductor laser 3 and the objective lens 10, and the laser light emitted from the semiconductor laser 3 is set to expand toward the objective lens 10.

As a result, the diameter of the reflecting mirror 9 of the galvanometer mirror 9 is compared with the diameter of the light before entering the objective lens 10.
5 can be reduced.

An optical head constituted by an optical system having such an arrangement is generally called a finite optical system head, and the light emitted from the semiconductor laser is converted into parallel light by a collimating lens before reaching the objective lens. Infinite optical system head.

[0017]

In an actuator that moves an object by the action / reaction of a current flowing through a coil and a magnetic flux generated by the current, the coil is reversed by passing a current in a positive direction and a current in a negative direction. Normally, one amplifier for one actuator is sufficient because of the available force.

On the other hand, in the case of the above-mentioned conventional galvanomirror in which the oscillating portion is moved by the Coulomb force acting on the electrode and the oscillating portion, since only Coulomb force generates attraction, a plurality of electrodes are used. , It is necessary to generate a reverse force by pulling from the opposite side. In an actuator that drives the swinging part by such Coulomb force,
For example, from the state where the electrodes 97a and 99b are charged and the swinging part 94 is rotated in one direction, the swinging part 94 is rotated in the opposite direction.
In order to rotate, the electrodes 97b and 99a different from the electrodes 97a and 99b must be charged, and torque must be applied to the oscillating portion 94 by the Coulomb force.

Therefore, in the above-described conventional galvano mirror actuator, a plurality of electrodes having different polarities are required. However, using a plurality of electrodes necessarily requires a plurality of outputs, that is, an amplifier (amplifier). . Therefore, due to the offset of the plurality of amplifiers and the variation of the amplification factor, a force is applied in the oscillating portion 94 in a direction perpendicular to the reflection surface of the reflecting mirror 95 attached to the oscillating portion 94.

In the above-mentioned conventional galvano mirror, four electrodes are used. However, if four electrodes are provided,
The swing part 94 needs to be larger than the reflection mirror 95, and the drive sensitivity of the swing part 94 has been reduced.

The oscillating portion 9 is formed only by the electrodes 99a and 99b.
4 is driven, a bias voltage is applied to the electrodes 99a, 99a.
The oscillating portion 94 may be configured to be attracted toward the third plate 98 toward 99b so as to apply a rotational torque to the oscillating portion 94 by changing the voltage balance with respect to the drive input. However, even in the case of such a configuration, the force for attracting the swinging portion 94 to the third plate 98 is small.
There is a problem in that the control is changed by the drive input and stable control cannot be performed.

In the conventional galvanomirror 90, the thickness of the elastic body 93 is smaller than or the same as that of the oscillating portion 94 having the reflecting mirror 95, so that the oscillating portion 94 is perpendicular to the reflecting surface of the reflecting mirror 95. The rigidity to support in the direction was low.

In the head of the finite optical system, when the reflecting mirror 95 of the galvano mirror 90 moves in the direction perpendicular to the reflecting surface, the distance between the semiconductor laser 3 and the objective lens 10 changes, so that the light is focused by the objective lens 10. The focus position of the beam spot moves in the focus direction, and an offset also occurs in the position of the light incident on the objective lens. Therefore, the beam spot also moves in the tracking direction of the disk 1.

Therefore, in the conventional galvanomirror,
Since the rigidity of supporting the oscillating portion 94 in the direction perpendicular to the reflecting surface of the reflecting mirror 95 is low, when the oscillating portion 94 is rotated, the oscillating portion 94 vibrates in the direction perpendicular to the reflecting surface of the reflecting mirror 95. Thus, it has been difficult to realize stable control.

Also, if the rigidity for supporting the oscillating portion 94 in the direction perpendicular to the reflecting surface of the reflecting mirror 95 is low when an external force is applied to the optical disk device itself having the optical head 7,
The oscillating portion 94 easily vibrates in the direction perpendicular to the reflection surface of the reflection mirror 95, and it has been difficult to ensure resistance to disturbance.

When the oscillating section 94 vibrates in the direction perpendicular to the reflecting surface of the reflecting mirror 95, the focal position of the beam spot converged by the objective lens 10 does not move in the focusing direction, and the beam spot is In order to prevent the optical head 7 from moving in the one tracking direction, the optical head 7 may be configured by an infinite optical system. However, in order to make the optical head 7 an infinite optical system,
In addition to the necessity of a new collimating lens and the like, the cost is increased, and the reflecting surface 95 of the galvanomirror 90 can be made smaller than the diameter of the light before entering the objective lens 10. The advantage of the configuration cannot be achieved, which hinders the thinning of the optical disk device.

It is an object of the present invention to provide a galvanomirror capable of realizing stable control with a simple configuration, and a thin optical disk device having sufficient resistance even when an external force is applied.

[0028]

According to a first aspect of the present invention, there is provided a galvanomirror comprising: a oscillating portion having a reflecting mirror on a surface thereof; and a fixed portion disposed around the oscillating portion. And a pair of elastic portions for suspending and supporting the swinging portion on the fixed portion, and a convex portion formed on the back surface of the swinging portion so as to be continuous with the elastic portion.

According to a second aspect of the present invention, there is provided a galvanomirror having a oscillating portion having a reflection mirror on a surface thereof, a fixed portion disposed around the oscillating portion, and the oscillating portion suspended from and supported by the fixed portion. A pair of elastic portions, and a concave portion that is formed on one of the back surface of the swing portion and the surface of the fixed portion opposed thereto, and includes a portion that at least crosses a straight line connecting the pair of elastic portions, It is characterized by having.

The galvanomirror according to claim 3 is
A swinging portion provided with a holographic optical element formed on a surface thereof, a fixed portion disposed around the swinging portion, and a pair of elastic portions that suspend and support the swinging portion to the fixed portion, It is characterized by having.

According to a fourth aspect of the present invention, there is provided a galvanomirror in which a reflecting mirror is formed on a part of the surface, and a swinging portion having a hole of a predetermined shape in a portion where the reflecting mirror is not formed, and the swinging portion. And a pair of elastic portions for suspending and supporting the swinging portion on the fixed portion.

The galvanomirror according to claim 5 is
The hole according to claim 4, wherein the hole having the predetermined shape is formed at the center of the elliptical swinging portion.

The galvanomirror according to claim 6 is
5. The device according to claim 4, wherein the reflection mirror is formed substantially at the center of an elliptical swinging portion, and a plurality of holes having the predetermined shape are formed so as to surround the reflection mirror. I do.

According to a seventh aspect of the present invention, there is provided an optical disc apparatus comprising: a light source; an objective lens for converging a laser beam emitted from the light source on an information recording surface of the optical disc to form a light spot; An oscillating portion provided between the oscillating portions and having a reflection mirror formed on a surface thereof, a fixed portion located around the oscillating portion, a pair of elastic portions for suspending and supporting the outer periphery of the oscillating portion on the fixed portion; A galvanomirror having a convex portion formed continuously with the elastic portion on the back surface of the oscillating portion, and a straight line connecting the pair of elastic portions is formed between the information recording track of the optical disc and the objective lens. It is included in a plane including the optical axis and has an intersection with the information recording surface.

An optical disk apparatus according to claim 8 is provided with a rotation driving means for rotating the optical disk, a fixing means for detachably fixing the optical disk to the rotation driving means, and between the light source and the objective lens. An oscillating portion having a reflection mirror formed on a surface thereof, a fixed portion located around the oscillating portion, a pair of elastic portions for suspending and supporting the oscillating portion on the fixed portion, and a back surface of the oscillating portion. A galvanomirror having a convex portion formed continuously with an elastic portion, a feed mechanism for supporting an optical head including the galvanomirror movably in a radial direction of the optical disc, and information of the optical disc on the fixing means. An automatic centering mechanism for adjusting the distance between the center of the recording track and the rotation center of the rotation drive unit is provided.

According to the present invention as described above, since the rigidity of supporting the oscillating portion and the reflecting surface of the reflecting mirror in a direction perpendicular to the mass of the oscillating portion is high, the oscillating portion reflects the reflecting mirror. It is difficult to vibrate in the direction perpendicular to the plane, and thus, a galvanomirror with a simple configuration and high resistance to disturbance can be realized.

Also, by combining the galvanomirror, the feed mechanism of the optical head, and the automatic alignment device, an optical disk device having sufficient resistance to disturbance applied to the device can be realized.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a galvanometer mirror according to the present invention and an optical disk apparatus using the same will be described below with reference to the accompanying drawings. The configuration of the optical head to which the galvanomirror according to the present invention is attached is completely the same as the configuration described in the conventional apparatus with reference to FIGS. The configuration unique to the present invention is that the galvanomirror 9 in FIG. 13 is replaced with a galvanomirror 9A having a configuration as shown in FIG.

In FIG. 13, inside the optical head 7,
The galvanometer mirror 9 includes the semiconductor laser 3 and the objective lens 10
The laser light emitted from the semiconductor laser 3 is set so as to expand toward the objective lens 10. Thereby, the mirror surface of the galvanometer mirror 9 can be made smaller than the diameter of the light before the light enters the objective lens 10, and as a result, the optical head 7 can be formed thin.

The head of such a finite optical system has a simple structure and is suitable for thinning the optical disk device. However, when the reflection mirror of the galvanometer mirror 9 moves in the direction perpendicular to the mirror surface, the semiconductor laser 3 and the objective Since the distance of the lens 10 changes, the focal position of the beam spot condensed by the objective lens 10 moves in the focusing direction, and an offset also occurs in the position of light incident on the objective lens. There is also a disadvantage that the spot moves in the tracking direction of the disk 1.

In order to compensate for such a disadvantage, a galvano mirror 9A as shown in FIG. 1 is provided below the objective lens. The galvanomirror 9A has a structure in which two plates, a first plate 20 and a second plate 30, are stacked as shown in FIG. As shown in FIG. 2, the first plate 20 includes a guard part 21, a fixed part 22, a swing part 23, and a pair of elastic parts 25a and 25b.

The fixing portion 22 is fixed to the entire first plate 20 by being joined to the second plate 30. The oscillating portion 23 is formed so as to be surrounded by the guard portion 21 and the fixed portion 22 of the first plate 20, and has a mirror surface 24 for reflecting laser light from the semiconductor laser 3 on its surface. It is integrally formed by processing or the like. Further, the mirror surface 24 is formed by evaporating a metal thin film, a dielectric multilayer film, or the like on the surface of the oscillating portion 23.
In order to form the first plate 20 and the second plate 30 from, for example, a silicon wafer or the like, the swing portion 23 has a thickness of about 50 to 500 μm.

The elastic portions 25a and 25b are connected to the swinging portion 23 at one end and connected to the fixed portion 22 at the other end, so that the swinging portion 23 and the fixed portion 22 are connected and suspended and supported. ing. Here, the center of gravity of the mass of the oscillating portion 23 is configured to be exactly intermediate on a line connecting the pair of elastic portions 25a and 25b. On the back side of the mirror surface 24 of the swing portion 23, a convex portion 26 having the same thickness as the elastic portions 25a and 25b is provided like a beam connecting the pair of swing portions 23.

In other words, before the fixing portion 22, the elastic portions 25a, 25b, and the oscillating portion 23 are etched from the mirror surface 24 side to form the convex portion 26, the oscillating portion 23 is moved from the side opposite to the mirror surface 24. It has been etched beforehand. that time,
As shown in FIG. 2, the width t ₁ of the convex portion 26 is
Since the width is wider than the horizontal widths of the first and second plates a and 25b, the convex portion 26 and the elastic portions 25a and 25b are continuous due to an error when the etching is performed from both sides of the first plate 20 on the mirror surface 24 side and the opposite side. The possibility of disappearing is reduced.

As described above, the swing portion 23 has the convex portion 26 on the back surface.
When the convex portion 26 is continuous with the elastic portions 25a and 25b, the thickness of the elastic portions 25a and 25b is secured without increasing the moment of inertia of the swing portion 23 around the elastic portions 25a and 25b. Can be. Further, since the elastic bodies 25a and 25b can transmit the tensile compressive force to the convex portion 26, not only the rigidity is increased but also the oscillating force is increased with respect to the force for vibrating the oscillating portion 23 in the direction perpendicular to the reflecting mirror 24. Moving part 2
Since the inertial mass of No. 3 is reduced, the resonance frequency of the mode in which the oscillating portion 23 vibrates in the direction perpendicular to the reflecting mirror 24 can be raised, and the vertical vibration of the mirror surface 24 due to disturbance can be reduced.

The convex portion 26 is the mirror surface 2 of the swing portion 23.
It is not always necessary to be continuous on the back side of 4.
The shapes of the fixed portion 24, the swinging portion 23, and the pair of elastic portions 25a and 25b constituting the first plate 20 are formed by reactive ion etching (hereinafter referred to as RIE-Reactive Ion Etchi).
Abbreviated as ng-. ).

On the other hand, the second plate 30 is formed of an electrically insulating material such as a glass plate, or is formed of silicon having a surface coated with an electrically insulating material (or an oxide film). Electrostatic bonding, diffusion bonding, anodic oxidation bonding, to the fixed portion 22 of the first plate 20,
It is joined by any method such as joining via water glass. Further, as shown in FIG. 3, electrodes 31a, 31b
Are formed on the electrodes 31a and 31b.
32b is connected. Further, the second plate 20
The point which divides each of the two opposing points of the central part and the peripheral edge of the swinging part 23 into approximately two to one, and centering on points 33a and 33b,
A radially and annularly formed concave portion 34 is formed toward the outer periphery of the swing portion 23. The depth of these recesses 34 is set, for example, in the range of 10 to 300 microns.

As shown in FIG. 1, the recess 34 is
From the portion opposing the second plate 30 to the portion not opposing the swing portion 23 on the second plate 30, and furthermore, a part of the concave portion 31 is formed by the elastic portion 25 a,
When it is continued so as to intersect with the straight line on the second plate 22 facing the second plate 25b, the positive pressure and the negative pressure generated by the swing of the swing part 23 are released into the atmosphere, and the positive pressure and the negative pressure are reduced. cancel.

As a result, the pressure generated by the swing of the swing unit 23 is reduced, and as a result, the resisting force of the swing unit 23 when the swing unit 23 swings is reduced, and the swing unit 23 responds to the same driving force. The deflection angle can be increased, and the drive sensitivity can be improved. When the oscillating portion 23 rotates about the elastic portions 25a and 25b as a central axis, for example, if the pressure generated at the point 33a is a positive pressure, the pressure generated at the point 33b becomes a negative pressure. Also, assuming that the pressure generated at the point 33a is positive when the swinging part 23 is moved in the vertical direction of the reflection mirror 24, the pressure generated at the point 33b is also positive.

Therefore, as described above, when some of the recesses 34 are made continuous so as to intersect with the straight line on the second plate 30 facing the elastic portions 25a and 25b, the points 33a and 33
b, a pressure release channel is formed between
The pressure generated when rotating is reduced,
The pressure generated when the oscillating portion 23 is moved in the vertical direction of the reflecting mirror 24 does not decrease because no flow occurs between the points 33a and 33b.

Therefore, the swinging part 23 is connected to the elastic part 25a,
When rotating around the mirror 25b, the resistance is small, and when moving the oscillating portion 23 in the vertical direction of the reflection mirror 24, a high resistance is generated by the pressure of air. Therefore,
The galvanomirror 9A maintains a high drive sensitivity and has a configuration in which the oscillating portion 23 is not easily moved in the vertical direction of the reflecting mirror 24 by an external force applied to the device.

The second plate 30 has a projection 35,
36 are formed. This is, in other words, the electrode 31
The surface 37 on which the a and 31b are formed is formed by etching the second plate 30 made of a wafer to form the convex portion 3.
It is dug down from the upper surface of 5,36. As described above, the fixing portions 21 and 22 are fixed to the entire first plate 20 by being joined to the second plate 30, but the first and second plates 20 and 30 are fixed to the fixing portion. 21
And the convex portion 35, and the fixing portion 22 and the convex portion 36, respectively.

Further, the convex portion 36 has a larger size than the fixed portion 22.
The area when viewed from a direction perpendicular to the reflection surface of the swing portion 23 is small. Further, a notch groove 38 is formed in the protrusion 36 from the inside of the protrusion 35 toward the end of the second plate 30. By providing the convex portion 36 smaller than the fixed portion 22 and providing the concave portion 38, for example, when the above-described mirror surface 24 is formed by vapor deposition of metal, the swing portion 2
Only 3 is surrounded by a perforated mask, and there is no need to deposit metal only on the swing portion 23.

That is, even if metal is deposited on the entire plate without using a mask, the convex portion 36 is smaller than the fixing portion 22, so that the swinging portion 23 and the electrodes 31a and 31b are not short-circuited, and are further fixed. No metal is deposited on the second plate 30 under the elastic bodies 25a and 25b around the portion 22, and the fixing portion 2 is formed by the notch groove 38.
Since the second plate 30 is also separated outside of 2,
There is no electrical short circuit between the electrodes 31a and 31b.
This eliminates the need to align the mask with the plate, thereby reducing man-hours.

The electrodes 31a and 31b are electrically connected by terminals 32a and 32b, respectively. Then, a voltage can be applied to the electrodes 31a and 31b by applying a voltage to the terminals 32a and 32b from outside.

On the other hand, the terminals 27a,
27b are formed. Since these terminals 27a and 27b are connected to the ground level, the swinging part 23 is always connected to the ground level. Therefore, the danger of floating substances such as dust adhering to the reflecting mirror 24 on the oscillating portion 23 is greatly reduced, and the performance of the galvanomirror 9A is maintained for a long time. However, the electrodes 31a and 31b and the terminal 32
a and 32b are designed so as not to be electrically connected to the first plate 20 side.

More specifically, a gap of about 1 to 20 μm is formed between the electrodes 31 a and 31 b and the first plate 20 by the projection 36. Also, on the surface 37 on which the electrodes 31a and 31b are formed,
Only the surface on which the electrodes 31a and 31b are formed and a part of the periphery thereof are formed above in FIG. 3, and the gap between the convex portion 26 of the oscillating portion 23 and the surface 37 and the convex portion 26 of the oscillating portion 23 are formed. The gap between the other surfaces and the electrodes 31a and 31b may be adjusted independently. It is preferable that the materials of the first plate 20 and the second plate 30 have substantially the same thermal expansion coefficients.

The galvanomirror 9 A according to the first embodiment having the above-described configuration includes a terminal provided on a part of the optical head 7,
The terminals 35a, 35b provided on the galvanometer mirror 9A,
36a and 36b are electrically connected by solder or the like,
In addition, the connection is mechanically strong.

Next, a specific operation of the galvanomirror 9A according to the first embodiment will be described. First, the terminal 32
By applying an initial potential to the terminals a and 32b, a potential difference is generated between the ground and the ground, so that the oscillating portion 23 having the potential of the ground and the electrodes 31a and 31b are attracted by Coulomb force. Here, when the voltage applied to the terminal 32a and the terminal 32b is changed, the swing portion 23 and the electrode 31a are changed.
The force of attraction between the electrode and the electrode 31b changes, and a couple acts, so that the two elastic portions 25a and 25b are torsionally deformed, and the swinging portion 23 rotates around the Y axis in FIG.

When the oscillating portion 23 rotates about the Y axis in FIG. 1, light is emitted from the semiconductor laser 3 in the Z direction in the figure, and the light which has been bent by 90 ° by the prism 8 and travels in the X direction in the figure is a galvanomirror. Since it can be rotated around the Y axis in the figure at 9A,
The beam spot moves on the disk 1 in the tracking direction of the disk 1. In an actuator that moves an object by the action / reaction of a current and a magnetic flux flowing through a coil, a reverse current is obtained by flowing a current through the coil in a positive potential (+) direction or a negative potential (−) direction. Only one amplifier is used for one actuator.

On the other hand, when the oscillator is moved by the Coulomb force acting on the electrode and the oscillating portion, only the attractive force is generated by the Coulomb force. It is necessary to generate a directional force. In the actuator of the present invention that drives the oscillating portion 23 by Coulomb force, for example, from the state where the electrode 31a is charged and the oscillating portion 23 is rotated, the oscillating portion 23 is rotated at a high speed in the opposite direction. In this case, the only choice is to charge the electrode 31b and apply torque to the swinging part 23 by Coulomb force. Therefore, the actuator always requires a plurality of electrodes, and one control input obtained from the tracking error signal of the disk 1 is connected to the terminals 32a, 32b with respect to the ground level by some method.
Although it is necessary to distribute the voltage to be applied to each terminal, usually, an operational amplifier is connected to each terminal to adjust the potential of each terminal.

However, even if there is no variation in the operational amplifier and the resistance, the force by which the electrodes 31a and 31b pull the swing portion 23 toward the second plate 30 changes. Further, even if there is no variation as described above, the swinging portion 23 is formed by the following principle.
, A force that varies in the direction of the second plate 30 is applied.

The dielectric constant of a medium (usually air) interposed between the swinging part 23 and the electrodes 31a and 31b is set to ε,
The area of a, 31b is S, the swinging part 23 and the electrodes 31a, 31
The distance of b is d, the initial potential applied to the electrodes 31a and 31b is Vo, and the control input amount applied as a differential voltage to the electrodes 31a and 31b sent from the tracking offset signal is △.
V, a pair of elastic portions 2 at the operation positions of the electrodes 31a and 31b.
Assuming that the distance between the straight line connecting 5a and 25b and the straight line projected on the second plate 30 is r, the torque T acting on the swinging portion 23 and the force F for attracting the swinging portion 23 in the direction of the second plate 30. Is as shown in the following equations (1) and (2). T = 2 · ε · S · Vo · △ V · r / d ² (1) F = ε · S · (Vo ² + △ V ² ) / d ² (2) Formula for calculating force F Since the control input amount △ V exists on the right side of (2), the force F changes due to the fluctuation of the control input amount △ V, and the oscillating unit 23 changes the force that changes in the direction of the second plate 30 by the control input. Will be applied.

As described above, according to the galvanomirror 9A having such a configuration, the swinging portion 23 has the convex portion 26 and the convex portion 26 is continuous with the elastic portions 25a and 25b. Without increasing the moment of inertia of the moving part 23 around the elastic parts 25a, 25b, the elastic parts 25a, 25b
And the elastic portions 25a and 25b can transmit a tensile force and a compressive force to the convex portion 26. Therefore, the rigidity is increased. In addition, since the inertial mass of the oscillating portion 23 is reduced, the resonance frequency of the mode in which the oscillating portion 23 oscillates in a direction perpendicular to the reflection mirror 24 is increased, and the vertical vibration of the mirror surface due to disturbance is reduced. can do. Therefore, even if a force fluctuating in the direction of the second plate 30 is applied to the swing portion 23, the amplitude can be reduced.

Even if the optical head 7 moves at a high speed in the X direction in the figure by the linear motor coil 12, the objective lens 10 is moved at a high speed in the Z direction in the figure, so that the focus joined to the optical head 7 is obtained. Even if the coil 11 receives the force due to the reaction, the external force acts on the optical disk device, and even if the force acts on the optical head 7, the vertical vibration of the mirror surface due to these disturbances is small.

As a result, the optical head 7 is
Even in a finite optical system in which the laser light expands from the laser beam toward the objective lens 10, since the distance between the semiconductor laser 3 and the objective lens 10 hardly changes, the focal position of the beam spot collected by the objective lens 10 It is difficult for the beam spot to move in the tracking direction of the disk 1 because it is difficult to shift in the direction and the position of the light incident on the objective lens is hardly offset. Therefore,
Although the configuration is simple and suitable for thinning the optical disk device, it is strong against disturbance and can realize stable control.

Since the driving force is generated by utilizing the electrostatic force, the power consumption can be reduced, and the optical unit 6 and the objective lens 1 mounted on the optical head 7 can be reduced.
Thermal adverse effects on 0 or the like can be avoided as much as possible. Further, the first plate 20 and the second plate 30 define a plane parallel to the reflection surface of the reflection mirror 24 as (1, 0, 0).
When the first and second plates 20 and 30 are formed as planes, (1, 0, 0) wafers having the largest market volume can be used as the wafers constituting the first plate 20 and the second plate 30.

Next, a galvanomirror according to a second embodiment of the present invention and an optical disk apparatus using the same will be described. In the following description of each embodiment, the same components as those in the above-described first embodiment will be denoted by the same reference numerals, and redundant description will be omitted.

The second embodiment differs from the first embodiment in the cross-sectional shape of the recess 34 in FIG. That is, the concave portion 34 in the first embodiment is formed in a simple groove shape having a predetermined depth from the surface 37 as schematically shown in cross section in FIG. On the other hand, in the second embodiment, as shown in FIG.
Are formed.

Specifically, the recess 34 of the first embodiment is
For example, as shown in FIG. 4A, if the second plate 30 is formed by etching to a depth of, for example, 10 to 200 microns, the concave portion 34 swings in the second embodiment. If the etching is performed from the surface facing the portion 23, the concave portion 39 is etched from the opposite side, that is, the side of the second plate 30 not facing the swinging portion 23, and both are etched by the second plate 30.
It is continuous inside.

Since the etching of the concave portion 39 is performed over a long depth excluding the depth of the concave portion 39 from the thickness of the second plate 30, anisotropic etching using potassium hydroxide or the like is suitable. . In the second embodiment, the recess 51 and the plurality of recesses 50 are continuous, but one recess 39 may be provided for one recess 34.

As described above, when the concave portion 34 is released to the atmosphere by the concave portion 39, the effect of reducing the pressure of the concave portion 34 is increased, and the resistance when driving the swinging portion 23 is reduced. The drive sensitivity of the oscillating portion 23 increases. As a result, in the tracking direction only, the beam spot is shifted by the offset of the position of the light incident on the objective lens due to the magnitude of the drive sensitivity in the tracking direction.
Can be reduced.

Next, an integrated optical device using a galvanomirror according to a third embodiment of the present invention will be described. The integrated optical device according to the third embodiment is arranged such that the X, Y, and Z axes shown in FIG. 5 coincide with the X, Y, and Z axes shown in FIGS. The third embodiment is different from the first embodiment, in particular, in that the galvanomirror 40 is arranged closer to the semiconductor laser 3 than the HOE 5 and the optical unit 6 of FIG. .

The integrated optical device 41 includes the photodetector 4
Is etched to form a recess 43 having a bottom surface formed in two steps. The semiconductor laser 3 is adhered to the upper bottom surface 44 of the concave portion 43, and the lower bottom surface 45 of the concave portion 43 and the surface on which the photodetector 4 is provided 45
The galvanomirror 40 is located at the line of intersection with the
The second plate 30 is formed so as to be joined so that the edges of the bottom surface thereof coincide with each other.

In the first embodiment, the galvanomirror 9A
In the place where has been arranged, a rising mirror made of a glass plate is arranged to bend the light traveling in the X direction in the figure by 90 ° in the Z direction in the figure.

The laser beam emitted from the semiconductor laser 3 rotates around the Y axis in the figure due to the rotation of the oscillating portion 23 of the galvanomirror 40. However, when the light beam rotates around the Y axis, the prism 8 rises. The light that is bent 90 ° by the mirror 24 and travels in the Z direction in the figure is rotated about the Y axis in the figure, and the beam spot collected by the objective lens 10 on the disk 1 moves in the tracking direction of the disk 1. Will be.

By arranging the galvanomirror 40 close to the semiconductor laser 3, the oscillating portion 23 can be formed very small. Conversely, if the oscillating portion 23 becomes small,
Since the rigidity against the force for deforming the swinging portion 23 can be sufficiently ensured, the thickness of the swinging portion 23 may be small.

As shown in FIG. 6, the oscillating portion 23 is formed by a thin film forming device such as a sputtering device, a vapor phase growth device, or a liquid phase growth device.
It is limited to about 1 to 10 microns.

Next, a method of manufacturing the galvanometer mirror 40 according to the third embodiment will be described. As shown in FIG. 6A, the galvanometer mirror 40 is made of a non-conductor such as glass forming the second plate 30 or a conductor such as a semiconductor such as silicon or a metal having an insulating film such as silicon nitride formed on the surface. A wafer 50 is prepared.
Next, as shown in FIG. 6B, the drive electrodes 31a and 31b
To form At this time, as in the first embodiment, the recess 3
4 may be formed.

Next, as shown in FIG. 6C, a sacrificial layer 51 of, for example, silicon nitride is formed on the entire surface.
As shown in (d), the sacrificial layer 52 made of polyimide or the like is used.
Is formed over the entire surface, and the surface of the sacrificial layer 52 is polished and flattened as shown in FIG.

Further, as shown in FIG. 6F, the elastic portion 25 has the same width as the width t1 of the convex portion 26 when viewed from the direction perpendicular to the reflection surface 24 of the galvanometer mirror 40.
The groove 53 is formed by etching the sacrifice layer 52 over the length of the end portions a and 25b, and the portions corresponding to the fixing portions 21 and 22 are etched together with the sacrifice layers 51 and 52.
In FIG. 6, a portion corresponding to the fixing portions 21 and 22 is not shown. At this time, the portion corresponding to the fixing portion 24 may be etched only by etching the sacrificial layer 52.

Next, as shown in FIG.
A thin film 54 made of, for example, metal, silicon, or a dielectric material, which is the material of No. 3, is formed by a thin film forming apparatus such as a sputtering apparatus, a vapor phase growth apparatus, and a liquid phase growth apparatus. This thin film 54
Is polished and flattened as shown in FIG.
Next, as shown in FIG. 6 (i), the swing part 23, the fixed part 2
The first and second elastic portions 25a and 25b are formed by dry etching such as RIE.

Further, as shown in FIG. 6 (j), the sacrificial layer 52 is removed, and as shown in FIG. 6 (k), the wafer 50 is cut and separated (diced) to separate from the wafer 50. To the second plate 30. Finally, as shown in FIG. 6 (l), the sacrifice layer 51 is removed,
The galvanometer mirror 40 is completed.

The manufacturing process shown in FIG. 6 may be performed in a different order. However, if the sacrificial layer 51 or the sacrificial layer 52 is completely removed before dicing, the elasticity due to vibration at the time of cutting is reduced. Since the portions 25a and 25b may be damaged, it is preferable to perform dicing in a state where the swinging portion 23 is joined to the second plate 30 by at least the first sacrificial layer 51.

With the galvanomirror 60 having such a structure, the same effect as in the first embodiment can be obtained. Further, since the swing portion 23 can be formed smaller than in the first embodiment, the drive sensitivity can be increased. Similarly, since the swing portion 23 can be made smaller than in the first embodiment, a large number of second plates 30 can be formed from the wafer 50, and the cost can be reduced.

Furthermore, the HOE 5 allows the galvanometer mirror 40 to be isolated from the external environment together with the semiconductor laser 3 and the photodetector 4 without using any special glass parts, so that the galvanometer mirror 40 is affected by humidity and dust. And the cost can be reduced by the amount of the glass parts.

In the third embodiment, the integrated optical device 41 is described as being composed of one silicon plate 42. However, in order to accurately form the positions of the surfaces 44, 45, and 46, the integrated optical device 41 is required. 41 may be configured by laminating a plurality of plates.

Next, a fourth embodiment of the present invention will be described.
FIG. 7 shows a galvanomirror 55 according to a fourth embodiment of the present invention.
FIG.

In the fourth embodiment, the HOE 56 is formed on the swing part 23 of the galvanomirror 55. Since the oscillating portion 23 is formed of silicon or the like as described above, the shape of the oscillating portion 23 is less deformed at the time of etching than glass, and a groove 57 finer than glass can be formed. Can be processed. Further, the cost can be reduced by the amount of the HOE 5, and the weight of the optical head 7 can be reduced. For this reason, the optical head 7 can be moved at a high acceleration with respect to the force generated by the linear motor coil 12. Since it is possible to follow in the tracking direction, it is possible to secure a margin against an external force applied to the optical disk device.

Next, a fifth embodiment of the present invention will be described.
FIG. 8 shows a galvanomirror 60 according to a fifth embodiment of the present invention.
It is a perspective view of. In FIG. 8, a plurality of holes 62 are provided on the periphery of the swinging portion 23 of the galvanometer mirror 60.
A reflection mirror 62 is provided at the center of the swing portion 23 where the hole 61 is not provided.
Are formed.

When the swinging portion 23 having the hole 61 is formed,
Although the electrodes 31a and 31b for driving the swinging portion 23 can be relatively large, the formation of the hole 61 in the swinging portion 23 does not greatly increase the moment of inertia of the swinging portion 23. . As a result, the drive sensitivity of the oscillating portion 23 in the tracking direction is improved, and as a result, the problem that the beam spot shifts in the tracking direction of the disk 1 due to the offset of the position of the light incident on the objective lens can be reduced.

Next, a sixth embodiment of the present invention will be described.
FIG. 9 shows a galvanomirror 65 according to a sixth embodiment of the present invention.
It is a perspective view of. In FIG. 9, a hole 66 is provided at the center of the swinging portion 23 of the galvanometer mirror 65. Hole 6
6 and the side wall 67 of the hole.
The antireflection film 69 is applied to the edge 68 of the hole.

When the oscillating portion 23 is formed in this manner, the reflected light from the galvanometer mirror 65 does not reach the central portion of the high-speed objective lens 10 incident on the objective lens 10, so that the objective lens 10 collects the light on the disk 1. A light beam spot can be formed small. As a result, the beam spot becomes smaller at least in the tracking direction of the disk 1, so that a margin for an error allowed when controlling in the tracking direction is expanded. As a result, it is possible to reduce the influence of the beam spot being shifted in the tracking direction of the disk 1.

Next, a seventh embodiment of the present invention will be described with reference to FIGS. In FIGS. 10 to 12, X, Y, and Z axes are added for convenience of description, but FIG.
3 to 17 have no relation to the X, Y, and Z axes shown in FIG.

In the optical disk device 70 according to the seventh embodiment, as a fixing means in which a permanent magnet formed of a magnetic material for clamping the disk 1 is joined to the spindle motor 2 as a rotation driving means for stably driving the disk 1. The optical disc device having an automatic alignment device capable of freely moving the turntable 71 from the rotation center of the rotor 72 in the XY plane and positioning the rotation center of the rotor 72 with respect to the track 73 of the disc 1 I have.

The disk 1 is stably clamped to the turntable 71. This clamping is performed by, for example, the magnetic attraction force of the permanent magnet 74 fixed to the turntable 71 and the magnetic material fixed to the disk 1. The turntable 71 is connected to the rotor 7 via a plate having a relatively large friction coefficient such as resin or hard rubber.
2, a preload is applied by the tensile force of the coil spring 75. This pulling force may be given by a magnetic material or the like.

Around the turntable 71 and the rotor 72, magnetic circuits 78a and 78b each composed of yokes 76a and 76b and coils 77a and 77b are formed. When the coils 77a and 77b are energized, they are formed of a magnetic material. Or the turntable 74 to which the permanent magnets are joined can be moved in either of the Y directions in the figure.

The rotation angle of the rotor 72 is obtained by detecting the magnetism of a rotating drive magnet (not shown) attached to the inside of the rotor 72 by a Hall sensor 80 formed on the drive base 79. Note that the rotation angle may be detected by the electromagnetic induction of the coils 77a and 77b.

The automatic alignment by the automatic alignment mechanism is performed by the rotor 7.
By rotating the turntable 71 and the disk 1 by rotating the disk 1, the number of track crosses from the tracking error signal detected by the photodetector 4 is counted, and by detecting the signal of the Hall sensor 80, the bias of the disk 1 is adjusted. It is detected by an arithmetic circuit 81 that calculates the absolute amount and direction of the core amount.

By rotating the rotor 72, the Hall sensor 8
By energizing the coils 77a and 77b while detecting the rotation angle of the rotor 72 by 0, the turntable 71 is driven in a direction opposite to the eccentric direction of the disk 1 until the eccentric amount becomes about 1 micron. This operation is continued, and when the amount of eccentricity becomes equal to or less than the predetermined amount, the current supply to the coils 77a and 77b is stopped, and the optical head is operated.

The disc 1 and the turntable 71, and the turntable 71 and the rotor 72, have a clamping force, a preload, and the like that do not cause any deviation within the range of the vibration and shock specifications specified for the optical disc device 70. Is given. Further, the clamping force and the preload may be configured to increase as the number of rotations increases due to a centrifugal clutch or the like.

The optical head 82 uses the same optical unit 6 as in the first embodiment, but the laser light emitted from the semiconductor laser 3 into the XY plane passes through the HOE 5 and is 45 ° with respect to this laser light. The light is reflected in the substantially Z direction in the figure by the galvanomirror 83 inclined to.

As shown in FIG. 12, the galvanometer mirror 9B has a pair of elastic portions 25a and 25b formed in oblique directions of the ellipse. The straight line connecting the pair of elastic portions 25a and 25b is parallel to the intersection line of the YZ plane in the drawing, which is the plane including the direction of the track 73 and the optical axis of the objective lens 10, and the plane parallel to the reflection surface of the galvanometer mirror 9B. It is formed to become.

The straight line connecting the pair of elastic portions 25a and 25b always crosses the disk 1 except for the case where the light emitted from the semiconductor laser 3 travels in the X direction in the figure and irradiates the galvanomirror 9B. Have a relationship.

When the light travels in the X direction, the straight line is parallel to the Y axis, and when the light travels in the Y direction, the straight line exists in the YZ plane. This is a straight line that forms an angle of 45 ° with the reproduction or recording / reproduction surface.

On the second plate 30, the electrodes 31a, 3
The electrodes 31a and 31b are also divided along a straight line connecting the pair of elastic portions 25a and 25b. Terminals 32a, 32b continuous with electrodes 31a, 31b
When a voltage is applied to the terminals 27a and 27b connected to the ground level and the terminals 32a and 32b, and the voltage applied to the terminals 32a and 32b has a difference, the oscillating portion 23 rotates around the elastic portions 25a and 25b. Due to the rotation of the oscillating portion 23, the reflecting mirror 24 formed on the oscillating portion 23 reflects light substantially in the Z direction in the figure, and the objective lens 10 changes the beam spot condensed on the disk 1 in FIG. In the tracking direction, which is the X direction.

As described above, the optical head 82 is configured such that the optical path 83 for guiding the light under the objective lens 10 is inclined with respect to the X direction which is the tracking direction in FIG. It can be compact. Further, as shown in FIG. 10, by setting the tracking direction in the diagonal direction of the optical disk device 70 having a rectangular shape, the optical disk device 70 is reduced in size to almost the same size as the disk 1, that is, equivalent to a so-called jacket size. be able to.

At this time, tracking feed of the optical head 82 is performed by a feed shaft 84 threaded and rotatably supported by a base (not shown), a drive motor 85 mounted on the base for rotating the feed shaft 84, and A shaft 86 which is not threaded and is fixed to the base;
A bearing 87 which is slidably fitted in the tracking direction and is integrally molded with the optical head 82 and a resin;
The optical head 82 is slidably fitted to the thread valley of the feed shaft 84 and receives a preload from the optical head 82 by a spring or the like (not shown).
4 is carried out by the action of the pawl 88 pressed against it.

More specifically, the optical head 82 is moved in the tracking direction (X direction) by a bearing 87, a feed shaft 84, and a shaft 86.
When the driving motor 85 rotates, the feed shaft 84 rotates, and the driving force in the tracking direction is transmitted from the claw 88 to the optical head 82.

According to the optical disk device 70 having the above configuration,
In controlling the tracking direction of the beam spot focused on the disk 1 by the objective lens 10, the eccentricity of the disk 1 is reduced to about 1 micron by an automatic alignment mechanism in advance, and the eccentricity of about 1 micron is The power consumption is small because the galvanomirror 9B driven by the correction is corrected.

In a general mechanism for removing eccentricity of the disk 1 by a two-axis actuator movable in the X and Z directions in FIG. 10 when an impact or the like is applied to the optical disk device, the amplitude of the two-axis actuator Is about 500 microns in the tracking direction, so that if an impact is applied during recording, data of several hundred tracks may be destroyed.

On the other hand, in the optical disk apparatus of the present invention, the optical head 82 is prevented from moving in the tracking direction by the engagement of the feed shaft 84 and the claw 88, and the galvanomirror 9
In B, as described in the first embodiment, since the gap between the swinging portion 23 and the electrodes 31a and 31b is about 1 to 20 microns, several hundred tracks of data are destroyed due to the rotation of the swinging portion 23. It is impossible. Therefore, it is possible to provide an optical disk device that has a simple configuration, consumes less power, and has sufficient resistance to external force applied to the device.

It should be noted that the present invention is not limited to the above-described embodiments and modified examples, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0114]

As described above, according to the present invention, a galvanomirror capable of realizing stable control with a simple structure and an optical disk device having sufficient resistance to external force applied to the device are provided. realizable.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a galvanomirror according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a back surface of a first plate according to the first embodiment.

FIG. 3 is a perspective view showing the surface of a second plate in the first embodiment.

4A is a sectional view of a second plate of the first embodiment, and FIG. 4B is a sectional view of a second plate of the second embodiment.

FIG. 5 is a perspective view of an integrated optical device including a galvanomirror according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a step of manufacturing the galvanomirror according to the third embodiment.

FIG. 7 is a perspective view showing a galvanomirror according to a fourth embodiment of the present invention.

FIG. 8 is a perspective view showing a galvanomirror according to a fifth embodiment of the present invention.

FIG. 9 is a perspective view showing a galvanomirror according to a sixth embodiment of the present invention.

FIG. 10 is a plan view showing an optical disc device using a galvanomirror according to a seventh embodiment of the present invention.

FIG. 11 is a perspective view showing an automatic alignment device used in a seventh embodiment.

FIG. 12 is a plan view showing a galvano mirror applied to a seventh embodiment.

FIG. 13 is a sectional view showing the internal structure of a general optical disk device including the present invention.

FIG. 14 is a plan view showing a drive system including a general optical head including the present invention.

FIG. 15 is a cross-sectional view showing a general optical head including the present invention.

FIG. 16 is a sectional view showing a general optical unit including the present invention.

FIG. 17 is an exploded perspective view showing a conventional galvanometer mirror.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Rotation drive means (spindle motor) 3 Semiconductor laser 9, 9A, 9B Galvano mirror 10 Objective lens 22 Fixed part 23 Swing part 24 Reflection mirror 25a, 25b Elastic part 26 Convex part 34 Concave part 37 Surface 56 HOE 71 Fixing means (Turntable)

Claims (8)

[Claims] An oscillating portion having a reflection mirror on a surface thereof; a fixed portion disposed around the oscillating portion; a pair of elastic portions for suspending and supporting the oscillating portion on the fixed portion; And a convex portion formed on the back surface of the swing portion so as to be continuous with the elastic portion. An oscillating portion having a reflection mirror on a surface thereof; a fixed portion disposed around the oscillating portion; a pair of elastic portions for suspending and supporting the oscillating portion on the fixed portion; A concave portion formed on one of the back surface of the oscillating portion and the surface of the fixed portion facing the oscillating portion, the concave portion including at least a portion crossing a straight line connecting the pair of elastic portions. mirror. 3. A oscillating portion having a holographic optical element formed on a surface thereof, a fixed portion disposed around the oscillating portion, and a pair of elastic members for suspending and supporting the oscillating portion on the fixed portion. A galvanomirror, comprising: 4. A oscillating portion having a reflection mirror formed on a part of the surface and having a hole of a predetermined shape at a portion where the reflection mirror is not formed, and a fixed portion disposed around the oscillating portion. And a pair of elastic portions for suspending and supporting the swinging portion on the fixed portion. 5. The galvanomirror according to claim 4, wherein the hole having the predetermined shape is formed at the center of the elliptical swinging portion. 6. The reflection mirror is formed substantially at the center of an elliptical oscillating portion, and a plurality of holes of the predetermined shape are formed so as to surround the reflection mirror. Item 6. A galvanometer mirror according to Item 4. 7. A light source, an objective lens for converging laser light emitted from the light source on an information recording surface of an optical disc to form a light spot, and provided between the light source and the objective lens;
An oscillating portion having a reflection mirror formed on a surface thereof, a fixed portion located around the oscillating portion, a pair of elastic portions for suspending and supporting the oscillating portion on the fixed portion, A galvanomirror having a convex portion formed continuously with the elastic portion, wherein a straight line connecting the pair of elastic portions is included in a plane including the information recording track of the optical disc and the optical axis of the objective lens. An optical disc device having an intersection with the information recording surface. 8. A rotation driving means for rotating the optical disk, a fixing means for detachably fixing the optical disk to the rotation driving means, and a reflection mirror formed on a surface between the light source and the objective lens. Oscillating portion, a fixed portion located around the oscillating portion, a pair of elastic portions for suspending and supporting the oscillating portion on the fixed portion, and a back surface of the oscillating portion connected to the elastic portion. A galvanomirror having a convex portion formed thereon, a feeding mechanism for supporting an optical head including the galvanomirror movably in a radial direction of the optical disc, a center of an information recording track of the optical disc on the fixing means, An automatic centering mechanism for adjusting a distance between a rotation center of the rotation driving means and the rotation center of the optical disk device.