JPH09146031A - Galvanomirror and optical disk using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a galvaomirror lightweight and small-sized in constitution possible to perform high-speed seeking. SOLUTION: The galvanomirror 9 is constituted by laminating a first plate 21 and a second plate 22. The first plate 21 consists of a stationary part 24, an oscillating part 25 and two elastic parts 26 which are integrally molded by anisotropy etching of a semiconductor mainly composed of silicon. The second plate 22 is formed out of an electrically insulating material, for example, glass plate, and is joined to the stationary part 24 of the first plate by means, such as electrostatic joining. First and second electrodes 28, 29 are arranged in the positions symmetrical with the elastic parts 26. These first and second electrodes 28, 29 have polarities reverse to the polarities of the part 25 and are changeable to arbitrary potential. Namely, dynamic rotating displacement occurs in the static displacement in a direction orthogonal to a reflection mirror surface. On the other hand, the dynamic displacement in the direction orthogonal to the reflection mirror surface is not excited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvanometer mirror for reflecting laser light in a predetermined direction, a method for manufacturing the same, and an optical disk equipped with the galvanometer mirror while changing the direction of light incident on an objective lens. The present invention relates to an optical disc device that records and reproduces information on and from the optical disc device.

[0002]

2. Description of the Related Art As is well known, a compact disk (C
As represented by D) and a laser disk (LD), an optical disk device that reproduces information using a laser beam is widely used. Recently, the optical disk device has been used as a storage device of a computer.

In addition, high-speed movement of an optical head equipped with an optical system has been required so that high-speed recording and reproduction of data can be performed. In response to such a demand for high-speed movement of the optical head, a method has been proposed in which the mass of the optical head is reduced as much as possible to realize a quick seek. As such a method, a separation optical method is adopted in which a semiconductor laser (light source) or a photodetector (detector) is not mounted on an optical head, and only an objective lens for forming a focal point on an optical disk is mounted on an optical head and moved. ing.

An example of the separation optical system will be described below with reference to FIG. Semiconductor laser 111 and photodetector 112
The fixed optical system 113 is fixed to a base (not shown). Laser light emitted from semiconductor laser 111
L is given to an objective lens 116 mounted in an optical head 115 via a galvanometer mirror 114 which is also fixedly arranged. The objective lens 116 forms a focal point on a pit on the optical disk D, and guides the reflected light to the photodetector 112 again in the reverse path. The optical head 115 is driven in a tracking direction X and a focusing direction Y by driving means (not shown).

According to such a system, the optical head 115
Can be corrected by controlling the swing angle of the fixedly disposed galvanometer mirror 114 when the optical path is tilted in the tracking direction X (a change in the incident angle of the laser beam on the objective lens 116). it can. Therefore, it is not necessary to mount a means for tilting the objective lens 116 itself on the optical head 115, so that the mass of the entire optical head 115 can be reduced, and a quick seek can be realized.

The conventional galvanometer mirror 114 used in this manner has a concrete structure shown in FIGS. 11 to 13. Here, FIG. 11 is a plan view of the galvano mirror 114, FIG. 12 is a sectional view taken along the line AA in FIG. 11, and FIG. 13 is B in FIG.
FIG. 4 is a cross-sectional view taken along line B.

The galvano mirror 114 includes a reflecting mirror 117 for reflecting the laser beam, an oscillator 118 to which the reflecting mirror 117 is fixed, and two supporting members for supporting the oscillator 118 with respect to the fixed portion 119. 120a and 120b. The fixing portion 119 is composed of a yoke 121 and a magnet 122, and applies a magnetic field to a coil 123 fixed to the side surface of the oscillating body 118 to support the reflecting mirror 117.
It can be swung around the axes 120a and 120b.

[0008]

However, there is a danger that the surface of the reflecting mirror 117 of the galvanometer mirror 114 will gradually tilt due to temperature changes and aging. If such an inclination occurs, it becomes difficult to accurately guide the reflected light from the galvanometer mirror 114 to the objective lens 116, and this may cause a tracking offset, which may hinder accurate tracking operation. is there. In addition, the influence of this inclination changes according to the distance from the galvano mirror 114 to the objective lens 116, so that complicated control such as further correcting the swing angle of the galvano mirror 114 by the current position of the optical head 115 is required. It will be necessary.

Therefore, only the galvanometer mirror 114 is mounted on the optical head 115, and the galvanometer mirror 114 and the objective lens are mounted.
There is a demand for a fixed optical system in which the distance from the optical system is kept constant.

However, as described above, the conventional galvanomirror 114 has a large mass since it has the yoke 121, the magnet 122, the coil 123, and the like, and when mounted on the optical head 115, the high-speed seek of the optical head 115 is hindered. It was virtually impossible. Therefore, an object of the present invention is to provide a lightweight and small-sized galvanometer mirror and an optical disk device capable of high-speed seek.

[0011]

In order to achieve the above object, according to the present invention, an oscillating body provided with a reflecting mirror and one end of which is connected to the oscillating body, and the oscillating body is suspended and supported so as to be swingable. A pair of supporting members, a fixed portion that is connected to the other end of the supporting member and faces the rocking body, and an electrode for driving the rocking body with an electrostatic force. The electrodes are first and second electrodes arranged at positions symmetrical with respect to an axis connecting the pair of support members.
The galvano mirror is provided with the above electrodes, and the first and second electrodes are independently controlled in potential so as to have a predetermined potential difference with respect to the oscillator.

Here, each of the first and second electrodes has substantially the same potential difference with respect to the oscillator, thereby suppressing oscillation of the oscillator, and different potential difference with respect to the oscillator. It is possible to cause the swinging body to swing by having. In addition, the first and second electrodes can be controlled to have the same polarity. Further, the substantially same potential difference that the first and second electrodes have with respect to the oscillator can be set to be larger than the potential difference during the tracking operation of the galvano mirror.

An oscillator having a reflecting mirror, a pair of support members having one end connected to the oscillator, and swingably supporting the oscillator, and the other end of the support member being connected. A fixed portion facing the rocking body and
In a galvanometer mirror having an electrode for driving the oscillator with electrostatic force, the electrode includes first and second electrodes arranged at positions symmetrical with respect to an axis connecting the pair of support members, By applying substantially the same potential to the first and second electrodes, an attractive force is generated so that the oscillator is balanced around the axis, and different potentials are applied to the first and second electrodes. Thus, the galvanometer mirror is configured to generate a suction force that causes the rocking body to rock around the axis.

Further, a light source for generating a laser beam, a galvano mirror for reflecting the laser beam from the light source, an objective lens for receiving a laser beam reflected by the galvano mirror to form a focus on an optical disk, and the galvano mirror. And a carriage on which the objective lens is mounted, a driving unit that drives the carriage in the radial direction of the optical disc, a reflected light from the optical disc, a driving signal to the driving unit, and a reproduction signal from the optical disc. In the optical disk device having a signal processing means for generating, the galvano mirror includes a rocking body having a reflecting mirror, and a pair of supports, one end of which is connected to the rocking body, for suspending and supporting the rocking body so as to be rockable. A member, a fixed portion connected to the other end of the support member and facing the rocking body, and the rocking member. An electrode for driving the body with an electrostatic force, the electrode including first and second electrodes arranged at positions symmetrical with respect to an axis connecting the pair of support members. The second electrode is an optical disk device in which the potential is independently controlled so as to have a predetermined potential difference with respect to the oscillator.

According to the present invention as described above, it is possible to realize a galvano-mirror having a lightweight and small structure and an optical disk device capable of high-speed seek without including elements having a large mass such as a yoke, a magnet and a coil.

Further, in the present invention, since the electric potential is independently controlled so as to have a predetermined electric potential difference with respect to the oscillator, in addition to the static displacement in the direction orthogonal to the reflecting mirror surface, a dynamic displacement is also caused. Rotational displacement occurs. In this case, the dynamic displacement in the direction orthogonal to the reflecting mirror surface is not excited. Therefore, it becomes possible to maintain highly accurate tracking operation while performing the signal recording operation and reproduction operation,
Good recording and reproducing characteristics can be obtained.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, an optical disk device equipped with the galvano mirror of the present invention will be described with reference to FIGS. Here, FIG. 1 is a sectional view showing the internal structure of the optical disk device, FIG. 2 is a plan view of a drive system including an optical head, and FIG.
Is a sectional view of the optical head, and FIG. 4 is a sectional view of the optical unit.

A disk 1 (optical disk, magneto-optical disk, etc.) used for recording and reproducing information is held by chucking means such as a magnet chuck with respect to a spindle motor 2 fixed to a base (not shown), During reproduction, the spindle motor 2 stably drives the rotation.

A semiconductor laser 3 for generating a laser beam for irradiating the disk 1 includes a photodetector 4 and a HOE (Ho
A logramic optical element) 5 and the like constitute an optical unit 6, which is fixed to the lower part of an optical head 7. It should be noted that a plurality of concaves and convexes are formed in the lower part of the optical unit 6 for the purpose of enhancing heat dissipation.

The laser light emitted from the semiconductor laser 3 passes through the HOE element 5 formed on the glass surface, changes its direction by 90 ° by the prism 8 fixed on the opposite surface of the HOE element 5, and the galvano mirror 9 ( The objective lens placed on the upper part of the optical head 7 after changing its direction by 90 ° again (details will be described later).
Guided to 10. And, from this objective lens 10,
A laser beam is focused on the recording track of 1 to form a focal point.

The reflected light from the disk 1 returns to the objective lens 10, passes through the galvanometer mirror 9 and the prism 8,
It is turned by the HOE element 5 and returned to the photodetector 4. A recording information signal, a focus offset signal, a track offset signal, etc. are generated from the reflected light taken into the photodetector 4. Then, by using the focus offset signal, a positional deviation of the objective lens 10 in the focusing direction is detected, and a control operation is performed in which a current is passed through the focus coil 11 so as to correct this positional deviation.
Further, by using the track offset signal, a positional deviation of the objective lens 10 in the track direction is detected, and a voltage is applied to the linear motor coil 12 and the galvano mirror 9 so as to correct the positional deviation, and a control operation is performed.

The objective lens 10 is held by an objective lens holder 13 made 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. . Electromagnetic action acts between the objective lens holder 13 made of a plastic magnet and the current flowing through the focus coil 11 fixedly wound around the optical head 7,
A focus driving force is generated in the objective lens.

The linear motor coils 12 are formed in a tubular shape, and one each is fixed to both side surfaces of the optical head 7. A total of four slide bearings 15 are formed on both sides of the optical head 7 with the linear motor coil 12 sandwiched between them.
The two guide shafts 16 extending in the radial direction are engaged with each other. This allows the optical head 7 to
It is supported so that it can move in the radial direction.

The guide shaft 16 is made of a magnetic material and also serves as a yoke of a magnetic circuit. Then, U-shaped back yokes 17 are fixed to both ends of the guide shaft 16. A radial magnet 18 is arranged at a position facing the linear motor coil 12 with the magnetic gap interposed therebetween, and is fixed to the back yoke 17. The guide shaft 16, the back yoke 17, and the radial magnet 18 form a radial magnetic circuit 19, and the linear motor coil
A magnetic field is applied to the magnetic head 12, and a driving force in the radial direction of the disk 1 is generated in the optical head 7 by an electromagnetic action with a current flowing through the linear motor coil 12.

FIG. 5 is a block diagram showing a processing procedure of the above-mentioned track offset signal. First, the track offset signal is converted into the first filter 41 and the second filter 42.
Respectively. Here, a kind of low-pass filter is adopted as the first filter 41. Therefore, the signal passing through the first filter 41 becomes a signal in the low frequency region and is used as a signal for the linear motor driver 43 and the linear motor coil 12. Further, the signal passing through the second filter 42 becomes a signal in the high frequency range, and the galvano mirror unit driver 44 and the galvano mirror
Used as a signal for 9. The signal processed in this way activates the linear motor coil 12 to drive the optical head.
It is used as a drive signal for 7 and as a control signal for the swing angle of the galvanometer mirror 9. 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.

Next, a specific structure of the galvano mirror 9 will be described with reference to FIGS. 6 to 8. 6 is an exploded perspective view showing a first embodiment of the galvano mirror, FIG. 7 is a sectional view thereof,
FIG. 8 is a plan view of the second plate.

As shown in FIG. 5, the galvanometer mirror 9 has a structure in which a first plate 21 and a second plate 22 are laminated. The first plate 21 has a hollow structure that is square-shaped. A semiconductor laser
A reflecting mirror 24 for reflecting the laser light from the laser beam 3, a swinging body 25 having the reflecting mirror 24 formed on its surface, and two elastic bodies for connecting the swinging body 25 to the first plate 21 ( And a support member) 26.

Here, the center of gravity of the mass of the movable portion, which is the total of the reflecting mirror 24 and the oscillating body 25, is configured to be in the vicinity of the middle on the line connecting the two elastic bodies 26. The reflection mirror 24, the oscillating body 25, and the elastic body 26 are integrally formed by anisotropic etching of a semiconductor mainly composed of silicon. Directly manufactured on.

The reflecting mirror 24 is formed so as to project from the rocking body 25 by 2 to 3 μm. Also, the elastic body 26
Are formed of a material that electrically insulates the oscillator 25 and the first plate 21.

The second plate 22 is joined to the first plate 21 by means such as diffusion bonding, diffusion bonding, or anodic oxidation bonding. The second plate 22 is formed of a glass-based member, and is electrically insulated from the first plate 21.

The first plate 21, the oscillator 25, and the second plate 22 are made of materials having substantially the same coefficient of thermal expansion, so that the influence of thermal strain on the oscillator 25 due to temperature changes. It is designed to prevent That is, as the second plate 22, a glass member having substantially the same coefficient of thermal expansion as that of the first plate 21 is selected.

On the other hand, at a portion of the second plate 22 facing the rocking body 25, a total of 2 portions are symmetrically formed with respect to a line connecting the two elastic bodies 26 (center line of the first plate 21). 2 electrodes
8,29 are provided. These electrodes 28 and 29 are formed on the second plate 22 by means such as vapor deposition and sputtering. The electrodes 28 and 29 may be transparent electrodes.

Next, the driving method of the galvano mirror 9 of the present invention will be described with reference to FIG. In the following description, the electrode 28 will be referred to as “first electrode” and the electrode 29 will be referred to as “second electrode”.
Of the electrode ”.

First, the oscillator 25 formed of a semiconductor is charged to, for example, +, and the first electrode 28 and the second electrode 29 are-
And to the same initial potential V0. In this case, the first
Since the attraction force generated by the electrode 28 and the attraction force generated by the second electrode 29 are balanced, no rotational torque about the swing axis is generated in the swing body 25.

When a rotational torque is applied to the oscillating body 25, the potential of the first electrode 28 is made larger than V0 by dV, and the potential of the second electrode 29 is made smaller than V0 by dV. . Then, the balance between the suction force generated by the first electrode 28 and the suction force generated by the second electrode 29 is lost, and two elastic bodies 26 are formed in the direction in which the swing body 25 and the first electrode 28 approach each other. The oscillating body 25 rotates by being twisted and deformed.

When the oscillating body 25 is rotated in the direction opposite to this direction, this time, the potential of the first electrode 28 is set to V0.
It is sufficient to make it smaller by dV and make the potential of the second electrode 29 larger than V0 by dV. Here, as dV, a value proportional to the rotational torque required to rotate the oscillating body 25 is set.

If dV becomes larger than V0 (that is, dV = 2V0), the potential of the electrode having the smaller potential is set to 0 as shown in FIG. No electric potential is applied. This is because if an electric potential in the opposite direction is applied, the oscillating body 25 and the electrode 28 or the electrode 29 will have the same polarity, so that the attractive force will not be generated.

Further, as the value of V0, during the normal tracking operation (the objective lens 10 by the linear motor coil 12)
It is preferable to set it to be larger than the value of dV necessary for controlling the reflection angle by the galvano mirror for assisting the positioning in the tracking direction. By setting in this way, the linearity between the potential and the deviation is maintained during the tracking operation.

By adopting the electrode control method as described above, dynamic rotational displacement is generated in addition to static displacement in the direction orthogonal to the surface of the reflecting mirror 24. On the other hand, the dynamic displacement in the direction orthogonal to the surface of the reflection mirror 24 will not be excited. Therefore, it is possible to maintain a highly accurate tracking operation while performing a signal recording operation and a reproducing operation, and it is possible to obtain a good recording and reproducing characteristic.

By setting the maximum applied voltage higher than the initial potential, the track pull-in range at the end of the seek operation can be widened. In the above example,
The case where the oscillator 25 is charged to + and the first electrode 28 and the second electrode 29 are charged to − has been described.
The same effect can be obtained by charging 25 to − and charging the first electrode 28 and the second electrode 29 to +. Further, when the oscillator 25 is connected to the ground and set to the state of zero potential, the same effect can be obtained by charging both the electrodes 28 and 29 positively or negatively.

By measuring the electrostatic capacitance between the oscillator 25 and the electrodes 28, 29, the gap length between the oscillator 25 and the second plate 22 can be detected. The rotation (swing) angle can be accurately detected. Then, by electrically correcting the tracking offset using the detected value, the restriction on the rotation angle peculiar to the galvanometer mirror can be almost eliminated, and stable and highly accurate tracking control can be performed.

Further, by using the change in the gap length between the oscillator 25 and the second plate 22 measured from the change in capacitance, the inclination of the reflecting mirror 24 surface due to temperature rise or change with time can be corrected. it can.

According to the galvano mirror 9 of the present invention having such a configuration, since it does not have elements having a large mass such as a yoke, a magnet, and a coil, it is possible to achieve a significant weight reduction as compared with the conventional one. Therefore, even if the galvanometer mirror 9 is mounted on the optical head 7, the optical head 7 can be kept lightweight and compact, and the optical head 7 can perform high-speed seek.

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 10 mounted on the optical head 7 can be reduced.
Thermal adverse effects on such devices can be avoided as much as possible.

The center of gravity of the oscillating body 25 is arranged on the rotation axis of the oscillating body 25, that is, on the line connecting the two elastic bodies 26, and rotation (swing) is realized by the torsional deformation of these elastic bodies 26. Therefore, even if the disturbance acceleration acts, it does not affect the rotational deformation.

Further, a galvanometer mirror composed of an electrostatic drive element that does not require any electromagnetic force is used for the electromagnetic drive element such as a coil or a magnet used to drive the objective lens 10. That is, by using the electromagnetic force and the electrostatic force, it is possible to almost completely prevent problems such as mutual interference of the driving forces. Therefore, the adverse effect of mounting the galvanometer mirror 9 on the optical head 7 can be eliminated, and the galvanometer mirror 9 can be removed.
9 and the objective lens 10 are extremely close to each other (see, for example, FIG.
It is also easy to arrange the device directly below the objective lens as shown in (1), and the degree of freedom in device design is greatly improved. Further, it is possible to suppress the movement of the optical axis center at the objective lens position due to the rocking and tilting of the galvanometer mirror, and as a result, it is possible to reduce the offset generated in the tracking and focus control signals and to reduce the spot position. It becomes possible to determine with higher accuracy.

Conventionally, the galvanometer mirror and the oscillator are joined together and the coil and the oscillator are joined together with an adhesive or the like. However, in the present invention, no inclusion such as an adhesive is used. . Therefore, the torque generated by the coil or the magnet is not transmitted through the adhesive layer, and the vibration frequency can be set to be extremely high. That is,
The drive frequency characteristics of the galvano mirror are not deteriorated due to insufficient rigidity of the adhesive part (for example, the resonance point is around 20kHz and it is impossible to servo to the high range). The control operation becomes extremely easy, and the positioning operation with high accuracy becomes possible.

The rotation axis of the oscillating body 25 and the longitudinal direction of the elastic body 26 are substantially coincident with each other, and the center of gravity of the oscillating portion 25 (movable portion) is on the line connecting the two elastic portions 26. It is configured to be near the middle of the. Therefore, even if disturbance acceleration acts on the device, it does not affect the rotational movement of the oscillating body 25.

Although the second plate 22 is formed of an electrically insulating material such as a glass plate in the above-described embodiments, an insulating layer of an oxide film is provided on the surface of a semiconductor mainly composed of silicon, for example. You may use the thing. Even with such a configuration, a similar effect can be obtained. It is needless to say that the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the spirit of the invention.

[0050]

As described above, according to the present invention, a galvanometer mirror having a lightweight and small structure and an optical disk device capable of high-speed seek are realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the internal structure of an optical disk device according to the present invention.

FIG. 2 is a plan view of a drive system including an optical head.

FIG. 3 is a plan view of a drive system including an optical head.

FIG. 4 is a cross-sectional view of the optical unit.

FIG. 5 is a block diagram showing a processing procedure of a track offset signal.

FIG. 6 is an exploded perspective view showing a galvanometer mirror according to the present invention.

FIG. 7 is a sectional view of a galvanometer mirror.

FIG. 8 is a plan view of a second plate.

FIG. 9 is a graph showing the relationship between the potential applied to the electrodes of the galvanometer mirror and the deviation.

FIG. 10 is a configuration diagram showing an example of a conventional separation optical system.

FIG. 11 is a plan view showing a conventional galvanometer mirror.

12 is a cross-sectional view taken along the line AA in FIG.

13 is a cross-sectional view taken along the line BB in FIG.

[Explanation of symbols]

 1 ... Disk 2 ... Spindle motor 3 ... Semiconductor laser 4 ... Photo detector 5 ... HOE element 6 ... Optical unit 7 ... Optical head 8 ... Prism 9 ... Galvano mirror 10 ... Objective lens 11 ... Focus coil 12 ... Linear motor coil 13 ... Objective lens Holder 14 ... Parallel leaf spring 15 ... Slide bearing 16 ... Guide shaft 17 ... Back yoke 18 ... Radial magnet 19 ... Radial magnetic circuit 21 ... First plate 22 ... Second plate 24 ... Reflective mirror 25 ... Oscillator (support member) ) 26 ... Elastic body 28,29 ... Electrode 41 ... First filter 42 ... Second filter 43 ... Linear motor driver 44 ... Galvano mirror unit

Claims (5)

[Claims] 1. An oscillating body having a reflection mirror, one end of which is connected to the oscillating body, and a pair of support members which suspendably support the oscillating body in a swingable manner, and the other end of the supporting member is connected. A galvanometer mirror having a fixed portion that is arranged to face the oscillator and an electrode for driving the oscillator with an electrostatic force, wherein the electrode is symmetrical with respect to an axis connecting the pair of support members. It is characterized in that it comprises first and second electrodes arranged at positions, and the first and second electrodes are independently controlled in potential so as to have a predetermined potential difference with respect to the oscillator. Galvano mirror. 2. The first and second electrodes have substantially the same potential difference with respect to the oscillator, thereby suppressing the oscillation of the oscillator, and providing different potential differences with respect to the oscillator. The galvanometer mirror according to claim 1, wherein the swinging member causes swinging of the swinging member. 3. The galvanometer mirror according to claim 1, wherein the first and second electrodes are controlled so as to have the same polarity. 4. An oscillating body provided with a reflecting mirror, one end of which is connected to the oscillating body, and a pair of supporting members which suspends and supports the oscillating body so that the oscillating body can oscillate, and the other end of the supporting member is connected. A galvanometer mirror having a fixed portion that is arranged to face the oscillator and an electrode for driving the oscillator with electrostatic force, wherein the electrode is symmetrical with respect to an axis connecting the pair of support members. A first electrode and a second electrode arranged at a position, and by applying substantially the same potential to the first and second electrodes, an attractive force is generated so that the oscillator swings around the axis, The galvanometer mirror is characterized in that by applying different electric potentials to the first and second electrodes, an attracting force that causes the rocking body to rock around the axis is generated. 5. A light source that generates a laser beam, a galvano mirror that reflects the laser beam from the light source, an objective lens that receives the laser beam reflected by the galvano mirror and forms a focus on an optical disc, and the galvano mirror. And a carriage on which the objective lens is mounted, driving means for driving the carriage in the radial direction of the optical disc, processing reflected light from the optical disc to generate a driving signal to the driving means and a reproduction signal from the optical disc. In the optical disc device having a signal processing means for generating, the galvano-mirror comprises: an oscillating body having a reflecting mirror; and a pair of one end of which is connected to the oscillating body and which suspendably supports the oscillating body. A supporting member; a fixing portion connected to the other end of the supporting member and facing the rocking body; An electrode for driving the moving body with an electrostatic force, the electrode including first and second electrodes arranged at positions symmetrical with respect to an axis connecting the pair of support members, and the first and second electrodes are provided. The optical disk device, wherein the second electrode is independently controlled in potential so as to have a predetermined potential difference with respect to the oscillator.