JPH04289527A - Mirror position adjusting device - Google Patents

Abstract

PURPOSE:To position a mirror for tracking in a prescribed neutral position. CONSTITUTION:The neutral position of a galvanomirror of a mirror device 15 is detected by a galvano servo circuit 86 and an error signal is formed in correspondence to the detection result thereof. This signal is synthesized with a tracking error signal via an adder 85 and the synthesized signal is supplied to the mirror device 15.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mirror position adjusting device suitable for use in a magneto-optical disk device.

0002

2. Description of the Related Art In a magneto-optical disk drive, when recording information on a magneto-optical disk, it is necessary to irradiate the disk with a laser beam and apply a predetermined magnetic field to the disk. In the case of the optical modulation method, the laser beam is modulated in accordance with the recording signal. At this time, a bias magnetic field directed in a predetermined direction is applied as the magnetic field. Furthermore, in the case of the magnetic field modulation method, laser light of a predetermined level is irradiated, and the applied magnetic field is modulated in accordance with the recording signal. In either method, it is advantageous to reduce the weight and size of the moving part of the pickup in order to shorten the access time to the magneto-optical disk. For this reason, pickups called separate-type pickups have recently been attracting attention.

FIG. 21 shows the basic configuration of such a separate pickup. A laser beam output from a fixed optical system 1 is reflected by a mirror 2 and is incident on a movable mirror 4. The mirror 4 reflects the incident laser beam and makes it enter the objective lens 5. The objective lens 5 focuses the incident laser light onto the magneto-optical disk 7 . A predetermined magnetic field is applied to the laser beam irradiation position from the opposite side of the magneto-optical disk 7 by a magnetic head (not shown). In this way, predetermined information is recorded on the magneto-optical disk 7 using the optical modulation method or the magnetic field modulation method.

The laser beam reflected by the magneto-optical disk 7 is incident on the mirror 4 via the objective lens 5, reflected there, and incident on the fixed optical system 1 via the mirror 2. In the fixed optical system 1, reflected light is separated from incident light and detected. It becomes possible to reproduce the signal recorded on the magneto-optical disk 7 from this detection signal.

[0005] When performing tracking control, the mirror 2 is rotated in a predetermined direction about an axis 3. Further, when performing focus control, the objective lens 5 is driven in a direction perpendicular to the magneto-optical disk 7. A tracking mirror 2 is rotatably fixed to a predetermined base. Therefore, the movable part 6 does not need to have a built-in tracking mechanism, and only needs to have a focusing mechanism built-in, thereby making it possible to reduce the size and weight. This allows high-speed access to the magneto-optical disk 7.

[0006]

By the way, the neutral position of the mirror 2 is adjusted so that the optical axis of the laser beam passes through the center of the objective lens 5 when the tracking error signal is zero. However, even if this neutral position is adjusted accurately, the adjusted position will deviate between when the device is used vertically and when it is used horizontally. Also,
This adjustment position may shift due to changes over time. When this deviation becomes large, the deviation between the optical axis of the objective lens 5 and the laser beam also becomes large, the level of the RF signal deteriorates, and in the worst case, the focus servo may become unlocked.

The present invention has been made in view of the above situation, and it is an object of the present invention to enable the mirror means to be always positioned at a predetermined neutral position.

[0008]

[Means for Solving the Problems] A mirror position adjustment device of the present invention includes a light generating means for generating light for recording or reproducing a signal on a recording medium, and a light generating means for directing the light generated by the light generating means in a predetermined direction. mirror means for reflecting and controlling deflection;
It is characterized by comprising a control means for detecting the position of the mirror means and controlling the neutral position of the mirror means in accordance with the detection result.

[0009]

[Operation] In the mirror position adjusting device having the above structure, the neutral position of the mirror means is detected by the detection means, and the neutral position of the mirror means is detected and controlled in accordance with the detection result. Therefore, it is possible to always position the mirror means at a predetermined neutral position.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows the structure of an embodiment of a pickup 25 of a magneto-optical disk device to which the mirror position adjusting device of the present invention is applied. The fixed optical system 11 includes a laser diode 12 and a photodiode 13, as well as a prism 14 that separates incident light and reflected light. The laser beam output from the fixed optical system 11 is guided to the movable part 16 via a tracking mirror device 15. The movable part 16 has a mirror 17 and an objective lens 18, and the objective lens 18 is supported via a leaf spring 19, and is movable in the direction toward and away from the magneto-optical disk 21. Further, the movable portion 16 is entirely movable in the radial direction of the magneto-optical disk 21 by a linear motor 20.

FIG. 3 shows a plan view of the optical path in the embodiment of FIG. 2, and FIG. 4 shows a more detailed configuration of the fixed optical system 11.

In this embodiment, the fixed optical system 11 includes a laser diode 12 that outputs a laser beam, a collimator lens 31 that converts the laser beam output from the laser diode 12 into parallel light, and a collimator lens 31 that converts the laser beam output from the laser diode 12 into parallel light. It has a grating 32 that divides the laser beam into at least three laser beams. grating 3
The laser beam divided into three beams by 2 is reflected by surfaces 14a and 14b of prism 14, respectively, and reflected by mirror device 15.
is incident on the The laser beam reflected by the mirror device 15 is incident on the mirror 17 of the movable part 16, reflected there, and incident on the objective lens 18. And objective lens 1
The laser beam output from 8 is irradiated onto the magneto-optical disk 21. One of the three laser beams divided by the grating 32 irradiates the track of the magneto-optical disk 21, and the other two beams irradiate the left and right edges of the track.

The laser beam reflected by the magneto-optical disk 21 is incident on the mirror 17 via the objective lens 18, reflected there, and incident on the mirror device 15. The laser beam reflected by the mirror device 15 is reflected by the surface 14 of the prism 14.
b, passes therethrough and enters the Wollaston prism 34. The Wollaston prism 34 splits the incident laser light into a P-polarized light component and an S-polarized light component in a direction perpendicular to the dividing direction by the grating 32 . The laser beam output from the Wollaston prism 34 is incident on the photodetector 13 via an intermediate lens 35 and a cylindrical lens 36 that provides astigmatism. The photodetector 13 has a light receiving area divided into four parts for generating a focus error signal based on a so-called astigmatism method, and a focus error signal is generated from the output thereof. It also has two areas that receive reflected light from the edges of the tracks on the magneto-optical disk 21, and from the difference in output, generates a tracking error signal based on the principle of the so-called push-pull method. Furthermore, it has two areas that receive a P-polarized light component and an S-polarized light component, and outputs a signal component (RF signal component) corresponding to recorded information based on the difference in output.

On the other hand, a portion of the laser beam reflected by the surface 14a of the prism 14 and directed toward the magneto-optical disk 21 is reflected by the surface 14a of the prism 14.
b and is detected by the photodetector 33. Since the output of the photodetector 33 is proportional to the intensity of the laser beam output by the laser diode 12, the output of the photodetector 33 is compared with a predetermined reference value, and the output level of the laser diode 12 is controlled in accordance with the difference. ,
So-called APC control is performed.

FIG. 5 shows a more detailed configuration of the mirror device 15. The fixed part 41 of the mirror device 15 is the horizontal part 4
2 and a vertical portion 43, and a center pin 44 is directly installed below the horizontal portion 42. Further, a V-groove 45 is formed on the front surface of the vertical portion 43, into which a rotation fulcrum shaft 46 is fitted. Further, holes 47a and 47b are provided in the vertical portion 43.
, 47c are formed, and screws 48a, 48b, 4 are formed, respectively.
8c is inserted. The tip of the screw 48a is screwed into the back surface of the rotating portion 51, and the tip of the screw 48b is also screwed into the back surface of the rotating portion 51. Similarly, the screw 48c is also screwed onto the back surface of the rotating portion 51.

Two horizontally arranged screws 48a and 48
Spring 49a and 49b are inserted through b,
Since the springs 49a and 49b are compressed between the heads of the screws 48a and 48b and the wall surface of the vertical part 43, the rotating part 51 is a rotating fulcrum fitted in a buoy groove 52 formed on the back surface of the rotating part 51. It is urged to rotate in the counterclockwise direction in the figure around the shaft 46. While the screws 48a and 48b are located below the rotation fulcrum shaft 46, the screw 48c
is arranged above the rotation fulcrum shaft 46. Therefore, the screw 48c prevents the rotating portion 51 from rotating counterclockwise. Therefore, by rotating the screw 48c and moving it forward and backward, the rotating portion 51 can be adjusted to a predetermined swing angle.

On the other hand, magnets 53 are arranged at the upper and lower parts of the front surface of the rotating part 51. The opposing surfaces of the magnets 53 are magnetized, for example, to the north pole, and the opposite sides are magnetized to the south pole. An assembly having a carbano mirror 63 attached to the front surface and a leaf spring 64 at the rear surface is fixed to the rotating part 51 so that the coil 62 wound around the outer periphery of the bobbin 61 is located in the magnetic field generated by the magnet 53. . Holes 64a and 64b for this attachment are formed on the left and right sides of the leaf spring 64. One of the two holes 64b is a round hole to determine the reference position, but the other hole 64a is an elongated hole to avoid applying unnecessary tension to the leaf spring 64 during installation. ing. Center hole 7 of leaf spring holder 71b
By inserting a screw (not shown) into 2b and screwing it into the hole 54b of the rotating part 51 through the hole 64b of the plate spring 64, the left side of the assembly including the galvanometer mirror 63 is connected to the rotating part 5.
Fixed to 1. Similarly, by screwing a screw (not shown) into the hole 54a of the rotating part 51 through the center hole 72a of the leaf spring holder 71a and the hole 64a of the leaf spring 64, the right side of the assembly having the galvanometer mirror 63 is assembled. is fixed to the rotating part 51.

Narrow portions 64c are formed on the left and right sides of the leaf spring 64 (only the right side portion is shown in the figure). Therefore, when a signal corresponding to the tracking error signal is supplied to the coil 62, an electromagnetic force is generated due to the cooperation with the magnet 53, and the galvanometer mirror 63 generates an electromagnetic force.
rotates clockwise or counterclockwise in the figure around the constricted portion 64c of the leaf spring 64.

The horizontal position of the mirror device 15 is shown in FIG.
As shown in FIG. 3, an eccentric driver (not shown) is inserted into the elongated hole 40 provided at the rear of the horizontal portion 42, and by rotating it, the mirror device 15 is rotated clockwise in FIG. It can be adjusted by rotating counterclockwise.

Next, referring to FIG. 1, a description will be given of a configuration for accessing a predetermined position (track) on the magneto-optical disk 21 using the pickup configured as described above.

The pickup 25 incorporates the above-mentioned laser diode 12, objective lens 18, photodiode 13, and the like. The output of the pickup 25 is input to a matrix amplifier 81. As described above, the matrix amplifier 81 generates a tracking error signal based on the push-pull method and supplies it to the phase compensation circuit 82. The phase compensation circuit 82 performs phase compensation on the input tracking error signal to a predetermined characteristic, and outputs the signal to a high-pass filter 83 and a low-pass filter 84. High pass filter 8
3 separates the high frequency component from the input signal. This component is a tracking error signal in the so-called narrow sense, and this tracking error signal is the switch SW1.
, are supplied to the coil 62 of the mirror device 15 via the adder 85. As a result, the galvanometer mirror 63 is rotated in the tracking direction by cooperating with the magnet 53. On the other hand, the low-pass filter 84 separates the low-frequency component (DC component of the tracking error signal) of the input signal and supplies it to the linear motor 20 via the switch SW2. The linear motor 20 moves the above-mentioned movable portion 16 in the disk radial direction of the magneto-optical disk 21 in response to the input signal. In this way, the pickup 25
are sequentially moved to predetermined positions on the magneto-optical disk 21, and signals can be recorded or reproduced on predetermined tracks.

On the other hand, a control circuit 90 containing, for example, a microcomputer reads the RF signal output from the pickup 25 and detects the position on the magneto-optical disk 21 where the pickup 25 is located. And input section 9
When a target value of a predetermined track to be accessed is input from 1, a predetermined drive signal is generated from the difference between the target value and the current position, and is supplied to the linear motor 20 via an adder 89 and a switch SW3. . At this time, the control circuit 90 controls the switches SW1 and SW, which are normally turned on during recording or reproduction.
2 is turned off, and switch SW3, which is normally turned off during recording or reproduction, is turned on. As a result, a so-called seek operation is started, and the linear motor 20 moves the movable portion 16 in the radial direction of the magneto-optical disk 21 at high speed. At this time, the moving speed and moving direction of the movable portion 16 are detected by a speed detection circuit 87 and a direction detection circuit 88, respectively. Direction detection circuit 8
The detection signal regarding the direction detected at 8 is sent to the control circuit 90
and is also supplied to the speed detection circuit 87. The speed detection circuit 87 outputs a signal corresponding to the moving direction and moving speed of the movable part 16 to the adder 89. Adder 89
subtracts the speed signal input from the speed detection circuit 87 from the drive signal input from the control circuit 90, and drives the linear motor 20 in accordance with the difference. This causes the linear motor 20 to drive the movable part 16 at a predetermined speed.

On the other hand, the error signal output from the galvano servo circuit 86 is supplied to the mirror device 15 via the adder 85 not only during the above-mentioned normal recording and reproduction but also during seek. Due to the stiffness, the galvanometer mirror 63 in the mirror device 15 is controlled so as to always be driven with the original neutral position as a reference.

Next, a specific example of the structure of the galvano servo circuit 86 will be explained.

FIG. 6 shows a first embodiment, and in this embodiment, a beam splitter 101 is disposed in the optical path of the laser beam reflected by the galvanometer mirror 63 toward the magneto-optical disk 21. As shown in FIG. As a result, a portion of the laser light directed toward the magneto-optical disk 21 is directed to the beam splitter 101.
The light is reflected by the condenser lens 102 and then condensed onto the photodetector 103 .

The photodetector 103 is divided into two regions 103a and 103b as shown in FIG.
The output of each region is input to a differential amplifier 104. As a result, an error signal corresponding to the deviation of the galvanometer mirror 63 in the mirror device 15 from the neutral position is generated from the differential amplifier 104. This error signal will be supplied to adder 85 in FIG.

That is, as shown in FIG.
If the galvanometer mirror 63 at 5 is shifted by an angle Δθ from the reference neutral position, the laser beam directed toward the magneto-optical disk 21 will be shifted by an angle 2Δθ. and,
When this galvanometer mirror 63 is rotated counterclockwise from the reference position as shown in FIG. 8(a), for example, the amount of light received by the photodetector 103b is
The amount of light received is greater than that of Further, as shown in FIG. 8B, when the galvanometer mirror 63 rotates clockwise, the amount of light received by the photodetector 103a becomes larger than the amount of light received by the photodetector 103b. Therefore, an error signal corresponding to the deviation of the galvanometer mirror 63 from the reference neutral position is generated from the difference between the outputs of the photodetectors 103a and 103b.

Note that, of course, this galvanometer mirror 63 is also driven in response to a tracking error signal. Therefore, in order to prevent the displacement corresponding to this tracking error signal from being detected, a low-pass filter 105 is connected to the output of the differential amplifier 104 as shown in FIG. It is possible to extract only lower frequency components.

FIG. 9 shows a second embodiment of the galvano servo circuit 86. In the embodiment of FIG. 6, the mirror device 15
The beam splitter 101 is inserted into the optical path of the laser beam reflected by the magneto-optical disk 21, but in the embodiment shown in FIG. reflect,
It is configured as a galvanometer mirror 63A that partially transmits light. In this way, there is no need to provide the beam splitter 101 as in the case shown in FIG.

In the case of the embodiment shown in FIG. 9, when the galvanometer mirror 63A is displaced by an angle Δθ as shown in FIG. 10, the optical axis of the transmitted component of the laser beam is translated by Δα. The direction and amount of movement are determined by the galvanometer mirror 6.
It corresponds to the displacement direction and displacement amount of 3A. Therefore, even in this case, the amount of displacement of the galvanometer mirror 63A can be detected from the difference between the outputs of the photodetectors 103a and 103b.

In the case of the embodiment shown in FIG. 9, the number of parts can be reduced by one compared to the embodiment shown in FIG. 6, but since the amount of displacement of the angle Δα is small, the detection level becomes small. Therefore, the embodiment of FIG. 6 is more suitable for obtaining a higher detection level.

FIG. 11 shows a third embodiment. In this embodiment, a galvano prism 63B is used as the galvano mirror 63. As a result, part of the laser light is guided to the magneto-optical disk 21 as in the embodiment of FIG. Can be done. In this case as well, as shown in FIG. 12, the amount of light received by the photodetectors 103a and 103b changes in accordance with the rotation angle of the galvano prism 63B, and the rotation position of the galvano prism 63B can be detected from the difference in output. Can be done.

However, in this embodiment, the mirror device 15
The mass of the moving parts increases, and more energy is required for tracking servo.

FIG. 13 shows a fourth embodiment. In this embodiment, the recording or reproducing laser beam output from the laser diode 12 is transmitted to the galvanometer mirror 63.
If the laser diode 112, the collimator lens 113, and the condenser lens 102 are incident on the plane perpendicular to the plane of the paper, and are reflected, and a photodetector 103 are arranged. In this case as well, the laser beam output from the laser diode 112 is incident on the galvanometer mirror 63 via the collimator lens 113, and the laser beam reflected there is divided into two via the condensing lens 102 to the photodetector 103.
focused on the top. Since the amount of light received by the two detectors 103a and 103b changes in accordance with the amount of rotation of the galvano mirror 63, it is possible to obtain a position correction signal for the galvano mirror in the same way as in the case described above.

The embodiment shown in FIG. 14 is a modification of the embodiment shown in FIG. 13, and in the embodiment shown in FIG.
A laser diode 112, a collimator lens 113, a condenser lens 102, and a photodetector 103 are arranged on the reflective surface 111 side of the laser diode 112, a collimator lens 113, a condenser lens 102, and a photodetector 103 in the embodiment of FIG. Photodetector 1
03 is arranged on the back surface 111a side of the galvanometer mirror 63c. Therefore, in the case of this embodiment, the thick part of the galvanometer mirror 63c is made of a light-transmitting material so that the laser light output from the laser diode 112 and made into parallel light by the collimator lens 113 is reflected on the back side of the reflective surface 111. It must be made of material. Of course, if the parallelism between the reflective surface 111 and the surface 111a on the opposite side is sufficiently ensured, the laser diode 1 can be
The laser beam output from 12 may be reflected.

FIG. 15 shows yet another embodiment. In this embodiment, a light emitting diode 121 and photodetectors 122 and 123 are arranged on the side of the surface 111a on the back side of the reflecting surface 111 of the galvanometer mirror 63 so as to face each other with the light emitting diode 121 in between. The light output from the light emitting diode 121 is reflected by the surface 111a of the galvanometer mirror 63, and is transmitted to the photodetectors 122 and 123.
is input. When galvanometer mirror 63 is in the correct neutral position, the outputs of photodetectors 122 and 123 are equal. On the other hand, when the galvanometer mirror 63 rotates clockwise or counterclockwise in the figure, the amount of light received by the photodetectors 122 and 123 changes. Therefore, the difference between the outputs of photodetectors 122 and 123 is converted into differential amplifier 10.
4, it is possible to detect the deviation of the galvanometer mirror 63 from the neutral position.

In the embodiment shown in FIG. 16, capacitance sensors 131a and 131b are installed near the upper and lower ends of the leaf spring 64.
is located. The capacitance sensor 131a is connected to a capacitance voltage conversion circuit 141a. Capacitance sensor 1
31a forms an oscillation circuit 150 together with capacitors C1 to C3, resistors R1 and R2, crystal resonator 151, and inverters 153 and 154. The oscillation frequency of the oscillation circuit 150 is changed in accordance with the output of the capacitance sensor 131a. The output of the oscillation circuit 150 is frequency-divided by a frequency divider 155 and then input to a phase comparison and low-pass filter 156.

The capacitance voltage conversion circuit 141a also includes capacitors C11 and C13, a varicap C12, and a resistor R11.
, R12, R13, crystal oscillator 161, inverter 16
It has an oscillation circuit 160 consisting of 2,163 circuits. The reference oscillation signal output from this oscillation circuit 160 is applied to the frequency divider 1
64 and input to the phase comparison and low-pass filter 156. The phase comparison and low-pass filter 156 compares the phase of the signal input from the frequency divider 155 and the phase of the signal input from the frequency divider 164,
A signal corresponding to the phase error is generated. Then, the phase error is smoothed by a low-pass filter, and the differential amplifier 10
Output to 4.

That is, when the galvanometer mirror 63 rotates, the position of the leaf spring 64 changes, and the capacitance sensor 131a
detects this change in the leaf spring 64 as a change in capacitance. As a result, the capacitive voltage conversion circuit 141a outputs a signal corresponding to the change in the position of the galvanometer mirror 63.

The output of the capacitance sensor 131b is connected to a capacitance voltage conversion circuit 141b configured similarly to the capacitance voltage conversion circuit 141a. As a result, a signal corresponding to a change in capacitance detected by the capacitance sensor 131b is transmitted from the capacitance voltage conversion circuit 141b to the differential amplifier 104.
will be supplied to Capacitance sensor 131a and 1
31b and the outputs of the capacitance voltage conversion circuits 141a and 141b, when one becomes large, the other becomes small. Therefore, the differential amplifier 104 outputs an error signal corresponding to the rotational position of the galvanometer mirror 63, as in the case described above.

FIG. 17 shows yet another embodiment. In this embodiment, a magnetoresistive element 1 is attached to a side surface 61a of a bobbin 61 to which a galvanometer mirror 63 is attached.
71 is attached. As shown in an enlarged view in FIG. 18, this magnetoresistive element 171 is formed and arranged in a strip shape so as to form an angle of 45 degrees with respect to the direction of magnetic flux generated by the magnet 53 (direction indicated by arrow A in the figure). ing. This magnetoresistive element 171 is electrically connected as shown in FIG. That is, the battery 181 is connected to one end of the magnetoresistive element 171, and the other end is connected to the current-voltage conversion circuit 182. The output of the current-voltage conversion circuit 182 is connected to the resistors R31 to R34 and the operational amplifier 1.
The signal is supplied to one input terminal of a differential amplifier 104 composed of 83. Further, the other input terminal of the differential amplifier 104 is connected to a reference voltage generation circuit 13 that generates a reference voltage V corresponding to the voltage at the normal neutral position of the galvanometer mirror 63.
5 is connected.

Next, its operation will be explained. When the angle β between the magnetoresistive element 171 and the direction of the magnetic field applied thereto is changed, the resistance value ρ(β) of the magnetoresistive element 171 changes as shown in the following equation. ρ(β)=ρ0−Δρsin2β If this equation is represented in a diagram, it will be as shown in FIG. As described above, in this embodiment, the direction of the magnetic flux generated by the magnetoresistive element 171 and the magnet 53 is set at 45 degrees. When the galvanometer mirror 63 rotates clockwise or counterclockwise, this angle β decreases or increases around 45 degrees. As a result, the magnetoresistive element 17
The resistance value of 1 will increase or decrease. battery 18
1, a predetermined voltage is applied to the magnetoresistive element 171, and as described above, the resistance value of the magnetoresistive element 171 changes in accordance with the rotational position of the galvanometer mirror 63. The output current value changes depending on the rotational position of the galvanometer mirror 63. The current-voltage conversion circuit 182 converts this change in current value into a change in voltage value. Differential amplifier 104 calculates the difference between the output voltage of current-voltage conversion circuit 182 and the voltage output by reference voltage generation circuit 135. Therefore, the output of the differential amplifier 104 becomes a signal corresponding to the rotational position of the galvanometer mirror 63.

In the above description, the mirror position adjustment device of the present invention is applied to adjustment of a tracking mirror in a magneto-optical disk device, but the present invention is also applicable to compact disk players, optical video disk players, etc. The present invention can be applied to a mirror device that performs tracking control or tangential control in other optical disc playback devices.

[0044]

As described above, according to the mirror position adjusting device of the present invention, the position of the mirror means is detected and the neutral position of the mirror means is controlled in accordance with the detection result, so that the device can be used easily. It becomes possible to always position the mirror means at a predetermined neutral position regardless of the state or aging.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of a mirror position adjustment device of the present invention.

FIG. 2 is a perspective view showing the configuration of an embodiment of the mirror position adjustment device of the present invention.

FIG. 3 is a plan view of the embodiment of FIG. 2;

FIG. 4 is a perspective view showing the configuration of the fixed optical system of the embodiment shown in FIG. 2;

FIG. 5 is a perspective view showing a more detailed configuration of the mirror device of the embodiment shown in FIG. 2;

FIG. 6 is a block diagram showing the configuration of a first example of the galvano servo circuit of the example of FIG. 1;

FIG. 7 is a block diagram showing the configuration of a circuit that processes the output of a photodetector in the embodiment of FIG. 6;

FIG. 8 is a diagram illustrating the operation of the embodiment of FIG. 6;

9 is a block diagram showing the configuration of a second embodiment of the galvano servo circuit in FIG. 1. FIG.

FIG. 10 is a diagram illustrating the operation of the embodiment of FIG. 9;

FIG. 11 is a block diagram showing the configuration of a third example of the galvano servo circuit of the example of FIG. 1;

FIG. 12 is a diagram illustrating the operation of the embodiment of FIG. 11;

FIG. 13 is a block diagram showing the configuration of a fourth example of the galvano servo circuit of the example of FIG. 1;

FIG. 14 is a block diagram showing the configuration of a fifth example of the galvano servo circuit of the example of FIG. 1;

15 is a block diagram showing the configuration of a sixth embodiment of the galvano servo circuit of the embodiment of FIG. 1; FIG.

16 is a block diagram showing the configuration of a seventh embodiment of the galvano servo circuit of the embodiment of FIG. 1; FIG.

17 is a sectional view showing the configuration of an eighth embodiment of the galvano servo circuit of the embodiment of FIG. 1. FIG.

FIG. 18 is an enlarged view of a part of FIG. 17;

19 is a block diagram showing the configuration of a circuit that processes the output of the magnetoresistive element in the embodiment of FIG. 17; FIG.

20 is an output characteristic diagram of the magnetoresistive element of the example of FIG. 17; FIG.

FIG. 21 is a perspective view showing the configuration of an example of a conventional mirror position adjustment device.

[Explanation of symbols]

11 Fixed optical system 12 Laser diode 13 Photo detector 15 Mirror device 16 Movable part 17 Mirror 18 Objective lens 21 Magneto-optical disk 25 Pickup 53 Magnet 62 Coil 63 Galvano mirror 64 Leaf spring 86 Galvano servo circuit

Claims (1)

[Claims] 1. A light generating means for generating light for recording or reproducing a signal on a recording medium; a mirror means for reflecting the light generated by the light generating means in a predetermined direction and controlling deflection; 1. A mirror position adjustment device comprising: control means for detecting the position of the mirror means and controlling a neutral position of the mirror means in accordance with the detection result.