JP3173085B2 - Magneto-optical disk recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to an optical disk recording and reproducing apparatus for writing and / or reading an information signal on a rewritable magneto-optical disk, details
Is a magnetic field modulation that generates an external magnetic field on the magneto-optical disk.
This is related to the support mechanism of the pad.

[0002]

2. Description of the Related Art Generally, a magnetic field modulation head of a rewritable magneto-optical disk is arranged as close as possible to apply a sufficient external magnetic field to the magneto-optical disk.
As a general method for maintaining the magnetic field modulation head at a predetermined gap (for example, 100 μm) with respect to the magneto-optical disk, during access to the magnetic field modulation head, the head is servo-controlled to always maintain the gap with the magnetic disk. There is a so-called non-contact type that keeps it constant.

A so-called contact type in which the magnetic field modulation head is brought into direct contact with the signal recording surface of the magneto-optical disk by a gimbal spring is used as an inexpensive method as compared with the non-contact type magnetic field modulation head described above. For example, it is widely known as seen on a floppy disk or the like.

[0004]

However, in either case of a non-contact type or contact type magneto-optical disk recording / reproducing apparatus, for example, when the apparatus is used outdoors, the magnetic field modulation head is affected by gravity and inertial force due to the attitude difference of the apparatus itself. And the normal positional relationship with the disc is lost. For example, in the case of the non-contact type, the gap (clearance) of the magnetic field modulation head with respect to the disk surface changes or unnecessary vibration occurs in the head. Had to be maintained at a predetermined value. In addition, in the case of the contact type, there is a problem that the disk surface is damaged by a strong pressure applied to the disk surface. As described above, when the apparatus is used outdoors or the like, no measures are taken against vibration and impact, so that the reliability is impaired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the magnetic field modulation head is kept stable with respect to the disk surface without being affected by gravity or inertia due to a difference in attitude of the apparatus. It is an object of the present invention to obtain a magneto-optical disk recording / reproducing apparatus which can maintain and improve earthquake resistance.

[0006]

In order to achieve the above object, a magneto-optical disk recording / reproducing apparatus according to the present invention comprises:
Optical pickup that irradiates a laser beam
Magnetic field for supplying an external magnetic field to the magneto-optical disk
Head and the magneto-optical disk surface adjacent to the magnetic field modulation head
Is provided on the other end via an elastic displacement part.
A first arm connected to the optical pickup device,
A balancer disposed on the other end of the first arm;
The other end is connected to the optical pickup device with the arm of
The first arm is attached to one end of the
A second arm provided with a regulating portion for regulating movement;
A bias for urging the first arm toward the surface of the magneto-optical disk
And a member. The magneto-optical device according to the present invention is
The disk recording / reproducing device uses a laser beam on a magneto-optical disk.
Optical pickup device for irradiating the system and magneto-optical disk
A magnetic field modulation head that supplies an external magnetic field to the
Is provided at one end and the other end is optically
A first arm connected to the pickup device;
A balancer provided at the other end of the arm;
The other end is connected to the optical pickup device together with the
On the end side between the magnetic field modulation head and the magneto-optical disk
And a second arm provided with a control unit for controlling the distance of
It is provided.

[0007]

The magneto-optical disc according to claim 1 constructed as described above.
According to the recording / reproducing apparatus, the first arm is
By providing a balancer that balances with the magnetic field modulation head
Weight and inertia that change as the posture of the device changes.
The first arm of the magnetic head is regulated
The movement of the magneto-optical disk in the direction of contact and separation is regulated by
Light is urged by an urging member that urges the magneto-optical disk surface.
The magnetic disk will be biased,
The sliding part can maintain the sliding of the magneto-optical disk surface.
Of the distance between the magneto-optical disk and the magnetic field modulation head.
Suppresses changes and is good for magneto-optical disks with a modulation head.
A good external magnetic field can be supplied. Claim 3
According to the magneto-optical disk recording / reproducing apparatus of the first aspect, the first arm
Creates a balancer that balances the magnetic field modulation head against gravity
The change in the posture of the device
Control of distance sensors, etc. without the influence of changing own weight or inertia force
The magnetic field modulation head is located at a position controlled by the unit,
This keeps the distance from the magneto-optical disk constant.
Good for magneto-optical disks with a modulation head.
A good external magnetic field can be supplied.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view of a main part of a recording / reproducing apparatus for a rewritable magneto-optical disk, and FIG. 2 is a partially cutaway front view of the main part. The case where the magnetic field modulation head is a contact type will be described.

The magneto-optical disk recording / reproducing apparatus includes an optical pickup device 2 disposed on the back side of the rewritable magneto-optical disk 1 and a magneto-optical disk 1 on the front side of the magneto-optical disk 1. And a magnetic field modulation head 3 disposed opposite to the optical pickup device 2 therebetween.

The magneto-optical disk 1 is mounted horizontally on a turntable 4 and a clamping plate 6 which is attracted by a magnetic force of a magnet 5.
And held between them. The magneto-optical disk 1 thus held is driven to rotate by a spindle motor 7 directly connected to the turntable 4.

The optical pickup device 2 includes an optical system 8 having a semiconductor laser and various lenses, an objective lens 9 for irradiating a laser beam focused on a magneto-optical disk, and a biaxial drive for driving the objective lens 9 in a tracking direction / focus direction. A pair of guide shafts 1 including a device 10 and having an optical pickup device 2 composed of these components arranged in parallel.
The magneto-optical disk 1 is supported by the motors 1 and 11 and can be moved in the radial direction of the magneto-optical disk 1 by a drive mechanism such as a linear motor (not shown).

On the other hand, the magnetic field modulation head 3 is provided in an arm mechanism 12 that moves in the inner and outer radial directions of the magneto-optical disk 1 in synchronization with the optical pickup device 2. Hereinafter, the details of the magnetic field modulation head 3 and the support mechanism thereof, which are main parts of the present invention, will be described with reference to the exploded perspective view shown in FIG.

The arm mechanism 12 includes a first arm 13 and a second arm 14. First arm 1
Reference numeral 3 denotes a metal channel processing material. A support plate 15 is provided on the rear end of the first arm 13 so as to extend horizontally from the lower edge to one side, and the upper edge is provided on the front end. A spring retainer 16 and an arm stopper 17 from the lower edge are provided to extend horizontally in the same direction as the support plate 15.

On the other hand, the second arm 14 is made of a hard plate-like plastic member such as nylon, and at the rear end side of the second arm 14 is formed a movable portion having a thin vertical shape. The support plate 19 is provided via the elastic displacement portion 18 of the first embodiment. Therefore, the arm 14 can rotate by deforming the elastic displacement portion 18 only in the vertical direction, and does not move in the horizontal direction without deforming the elastic displacement portion 18.

At the front end of the second arm 14, the above-mentioned magnetic field modulation head 3 comprising a head core 20 and a magnetic field modulation coil 21 is mounted on the lower surface thereof. The lower surface of the front end of the second arm 14 is provided with a spherical contact surface 23 adjacent to the magnetic field modulation head 3 and in contact with the magneto-optical disk surface.
Is mounted. The details of the slider 22 will be described later in detail.

Further, the arm 14 is provided with a balancer support arm 24 integrally extending rearward from one side in the vicinity of the elastic displacement portion 18.
A balancer 25 is inserted into 4 a and fixed with screws 26. That is, the arm 14 includes a balancer 25, a balancer support arm 24, a mounting shaft 24a thereof, a weight including the screw 26, and a weight of the magnetic field modulation head 3 and the slider 22 with respect to the gravity with the elastic displacement portion 18 as a fulcrum. Adjusted to balance.

The first arm 13 and the second arm 14 configured as described above are connected to the support arm plate 1 of the second arm 14 with the support plate 15 of the first arm 13 facing down.
9 are superimposed, and a screw 28 is screwed into a screw hole 27 of the mounting portion 2a of the optical pickup device 2 through the screw holes 15a and 19a of the support plate plates 15 and 19, respectively. 2 arms 13 and 1
4 is supported. At this time, the lower end of the second arm 14 at the front end side is supported on the arm stopper 17 of the first arm 13, and the second arm 14 is provided with a concave portion 29 provided at the front end thereof and the first arm 13. The spring is biased downward by a coil spring 30 interposed between the 13 spring retainers 16.

Thus, the magnetic field modulation head 3 and its supporting mechanism are configured as described above, and the slider 22 comes into contact with the signal recording surface of the magneto-optical disk 1, and the magnetic field modulation head 3 causes the signal of the magneto-optical disk 1 to move. The head 3 is arranged so that a predetermined gap is separated from the recording surface, and the magnetic field generation range of the head 3 is located almost directly above the focal point of the objective lens 9.
Thus, in synchronization with the movement of the optical pickup device 2 in the inner and outer radial directions of the magneto-optical disk 1, the slider 22 slides while contacting the surface of the magneto-optical disk 1 rotating at a high speed via the arm mechanism 12. It has been done. Slider 2
2 is spring-biased toward the disk 1 side via the second arm 14, but the arm 14 is in contact with the arm stopper 17 of the first arm 13 to restrict the downward movement. Therefore, the slider 22 is not strongly pressed against the disk surface.

The magneto-optical disk 1 rotating at a high speed in this manner
By making the slider 22 in contact with the surface so that the writing and / or reading operation of the magneto-optical disk 1 can be performed,
For example, even if the disk 1 has a skew or unevenness and the surface of the disk 1 oscillates, the first arm 14 can be rotated vertically by the elastic displacement portion 18 and the coil spring 27 can be used. The slider 22 can always follow the disk surface by the spring force of the magnetic field modulation head 3, so that the predetermined gap can be always maintained during the access of the magnetic field modulation head 3 to the signal recording surface of the magneto-optical disk 1.

Also, as shown in the embodiment of FIG. 2, the slider 22 is provided on the center side of the magneto-optical disk 1, that is, on the spindle motor side with respect to the magnetic field modulation head 3, so that the magnetic field near the outermost periphery of the magneto-optical disk 1 is changed. When the modulation head 3 accesses, the slider 22 can be prevented from coming into contact with unevenness due to uneven coating of the protective film, which is likely to occur near the outermost periphery of the disk, or skew on the outer periphery of the disk. A large external magnetic field can be generated.

Since the above-mentioned slider 22 moves while making contact on the signal recording surface of the magneto-optical disk 1, a member which does not damage the disk surface is used. Generally, nylon or polyoxymethylene (POM) or the like is used. Made of self-lubricating plastic material. As the contact surface 23 that directly contacts the disk surface, a point contact with the least load on the disk surface, that is, a so-called spherical contact surface is used.

The upper limit of the spherical radius of the contact surface 23 can be obtained as follows. Now, in FIG.
Is provided with a contact surface 23 having a radius R, and the maximum tilt angle of the magneto-optical disk 1 is defined as θ. The maximum tilt angle θ refers to a tilt angle with respect to an imaginary plane obtained by clamping a flat disk by zero run-out chucking. In general, this inclination angle is a value obtained by adding all of the maximum skew angle of the disk 1, the maximum inclination angle of the turntable 4, the verticality of the spindle motor 7 axis, the intersection of the arms 13, 14 and the slider 22, and the like. Therefore, from the above-described relationship, the contact surface 23
May be determined as a condition that a straight line having the maximum inclination angle θ touches R, that is, the maximum radius R _{max of the} contact surface.
= A / sin θ. For example, as an example, the radius of the slider 22 is 3 mm, and the maximum inclination angle θ is 1
°, the contact surface radius R is 150 mm. The numerical values described above for a formula on the theory, in the actual design the disk 1 and the slider 22 by setting some smaller R than the maximum radius R _max of the contact surface in anticipation of safety Reliability can be improved.

Now, the reason why the magnetic field modulation head according to the present invention is not affected by gravity or inertial force caused by a difference in attitude of the apparatus and can cancel these effects will be described.

The fact that one end of the arm 14 provided with the magnetic field modulation head (hereinafter referred to as the head 3) with the elastic displacement portion 18 as a fulcrum and the other end provided with the balancer 25 are balanced with respect to gravity. As you did. Therefore, the force with which the head 3 is pressed toward the disk 1 is only due to the spring force of the coil spring 30. This facilitates the design of the coil spring 30. That is, it is not necessary to consider the gravitational force acting on the head 3 as the force for pressing the disk 1. Further, this can prevent a change in the pressing force of the head 3 against the disk 1 due to a difference in the attitude of the apparatus. This is important in the case of equipment used outdoors. By the way, it is known from Einstein's theory of relativity as an equivalence principle that gravity and inertial force due to acceleration cannot be distinguished.

Here, the balance state of the arm 14 will be described as an example with reference to the schematic diagram of FIG. In the drawing, the mass on the side of the head 3 is M, and the elastic displacement portion 18 (hereinafter referred to as a fulcrum a).
Let L be the distance from to head 3 and balancer 2
The mass on the fifth side is m, and the distance from the fulcrum a to the balancer 25 is La. Now, assuming that an upward acceleration α is applied to the fulcrum a here, since it is balanced against gravity, the moment around the fulcrum a is considered, and mgL
a = MgL (g is gravitational acceleration), and is replaced by mLa = ML. By multiplying this equation by α, mαLa = M
αL. That is, this indicates that the entanglement is established by the inertial force due to the acceleration α.

That is, the arm 14 does not rotate even if acceleration other than the rotation direction is applied to the fulcrum a. This is true in all directions in which gravity balance is established with respect to the fulcrum a. Since the arm 14 does not rotate when the acceleration α is applied to the fulcrum a, the head 3 translates with the fulcrum a at this time. Since the fulcrum a is fixed to the fixed portion, and the disk 1 also moves in translation with the fixed portion via the shaft of the motor, no apparent force due to the acceleration α acts between the head 3 and the disk 1. become. In other words, the head 3 does not exert any external force on the disk 1 against external vibrations. Therefore, it can be proved that the pressing force of the head 3 is caused only by the coil spring 30, whereby the head 3 is connected to the apparatus. It can be understood that even if a difference in posture occurs, it can be set at a predetermined pressing force on the surface of the disk without being affected by gravity or inertial force.

FIGS. 6 and 7 show an embodiment in which the magnetic field modulation head is of a non-contact type. FIG. 6 is an exploded perspective view, and FIG. 7 is a sectional view of an assembled state. In this case, the difference from the contact type is that an actuator A is used to dispose the magnetic field modulation head 3 with a predetermined gap to the disk 1 surface.
Has been used. The actuator A includes a coil 31 housed in a recess 14 a provided at the front end of the second arm 14 and a support plate 3 provided at the front end of the first arm 13.
Yoke 34 and magnet 35 attached to screw 2 by screws 33
And assembled as shown in FIG. An optical distance sensor 36 for detecting the distance between the disk 1 and the head 3 is attached to the back surface of the second arm 14.

The servo drive of the non-contact type magnetic field modulation head 3 will be described with reference to the block diagram shown in FIG.
The distance sensor 36 always detects the distance from the disk 1, and the voltage from this sensor 36 is equal to the reference voltage 37.
The difference between these two voltages is amplified and sent to the drive amplifier 39 via the phase correction circuit 38. The drive amplifier 39 holds sufficient electric power to drive the actuator A. For example, when the distance between the disk 1 and the distance sensor 36 increases, the actuator A moves the second arm 14 with respect to the first arm 13. When the distance between the disk 1 and the distance sensor 36 is reduced, the actuator A can perform an operation to move the second arm 14 upward. As described above, in the above-described servo circuit, the magnetic field modulation head 3 follows the skew of the disk 1 so that the output voltage of the distance sensor 36 becomes equal to the reference voltage 37. In practice, the reference voltage 37 is adjusted by checking the distance between the disk 1 and the magnetic field modulation head 3, that is, the gap amount.

The provision of the balancer 25 in the non-contact type magnetic field modulation head constructed as described above allows the magnetic field modulation head 3 to be kept at a constant distance from the disk 1 by servo driving. 25
Keeps balance with the head 3 and is not affected by gravity or inertial force due to a difference in attitude of the apparatus as in the above-described embodiment.

FIG. 9 shows another embodiment of the second arm 14 of the contact type magnetic field modulation head. The arm 14 is formed by integrally molding the elastic displacement portion 18, the slider 22, and the balancer 25 with a hard plastic member such as nylon, or by integrally molding at least the two members described above.
The assembly process of the arm 14 can be labor-saving and can be manufactured at low cost. In the case of the second arm 14 described above, an opening 18a is cut out at the center of the elastic displacement portion 18, and short elastic displacement portions 18 are formed on the left and right sides of the opening 18a.
The second arm 14 can be stably rotated in the up-down direction.
Further, the balance with the balancer 25 can be easily adjusted by forming the lightening portion 41 in a part of the second arm 14.

FIG. 10 shows another embodiment of the movable portion of the second arm, that is, an opening 43 is cut out in a substantially strip-shaped metal plate 42 obtained by etching stainless steel or the like. On both side edges of 43 are formed narrow and narrow elastic displacement portions 44, 44 which are elastically deformed in the vertical direction.
A second portion made of a rigid material of a plastic material in which the magnetic field modulation head 3 and the slider 22 are provided at the distal end on the arm support plate 45 is provided on the arm support plate 45 on the front side of the elastic displacement portion 44 of the metal plate 42. The arm 14 is supported on a screw 47 and a part thereof by a screw 47 via a back plate 46.
A balancer 49 is attached to a mounting plate 48 provided at the rear end of the
It is fixed at 0. Then, the elastic displacement portion 44 of the metal plate 42
The mounting plate 51 on the rear side is mounted on the mounting portion 2a of the optical pickup device 2 with a screw 53 via a plate plate 52 from above.
It is fixed to.

With this structure, the vertical movement of the second arm 14 is changed to the elastic displacement portion 44 of the metal plate 42 instead of the elastic displacement portion 18 of the plastic material described with reference to FIG. In this example, the rigidity of the disk in the radial direction is particularly excellent, and therefore, there is an advantage that the positional accuracy of the magnetic field modulation head 3 can be easily obtained.

Further, the movable portion of the second arm 14 may be configured as shown in FIG. In this example, a pair of pivot shafts 54 and 54 are provided coaxially on the left and right portions on the rear side of the second arm 14, and a balancer 56 is fixed to the rear end of the arm 14 via a mounting shaft 55 with screws 57. is there. The second arm 14 has a pivot shaft 54 supported by a bearing portion 60 of a support plate 56 via a bearing 58, and the support plate 59 is fixed to the mounting portion 2a of the optical pickup device with a screw 61. . In this case, in order to facilitate the mounting of the pivot shaft 54 to the support plate 59, the support plate 59 is connected to the main body 59a and the side plate 59.
After the pivot shaft 54 is mounted on the bearing portion 60 via the bearing 58, the side plate portion 59b is fixed to the main body portion 59a with the screw 61.

In the hinge mechanism configured as described above, the vertical movement of the second arm 14 can be performed with the pivot shaft 54 as a fulcrum. As in the case of the moving part, the rigidity in the radial direction of the disk is excellent, and furthermore, compared with the moving part shown in FIGS.

The magnetic field modulation head support mechanism according to the present invention comprises:
Although described in detail as described above, the arm mechanism including the magnetic field modulation head 3 and the slider 22 has a state in which information signals are written to and / or read from the magneto-optical disk during the description of the embodiment. That is, the posture in which the slider 22 is in contact with the signal recording surface of the magneto-optical disk has been described. However, at the time of disk loading, the magnetic field modulation head 3 and the slider 22 together with the arm mechanism are moved by the arm flip-up mechanism (not shown). It's natural to try to avoid splashing and contact with the disc

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention. For example, FIG.
In the case of the contact type shown in FIG.
Although the example in which the balancer 25 of the arm 14 is provided on one side of the arm 14 is shown, the balancer 25 may be provided on both left and right sides of the arm 14. In the embodiment, the case where the magneto-optical disk 1 is used in a horizontal state is shown, but the present invention is also applicable to a magneto-optical disk recording / reproducing apparatus in which the magneto-optical disk 1 is used in a vertical state.

[0037]

As described above, the magneto-optical device according to the present invention is described.
In the disk recording / reproducing device, the first arm is
In addition to providing a balancer that balances with the magnetic field modulation head,
The first arm is moved by the first arm to the magneto-optical
The movement of the disc in the direction of contact and separation is restricted, and
A biasing member that biases the surface
The device is gravity
And the influence of inertia force
The balance between the head and the balancer is always established,
The tuning head is always in a stable posture with respect to the disk surface.
Maintain and improve the quake resistance of the recording / reproducing device for outdoor use
It is very suitable for In addition, the magneto-optical disk according to the present invention.
In the recording / reproducing apparatus, the first arm changes the magnetic field with respect to gravity.
A balancer that balances with the tuning head
The magnetic field modulation head is located at a position controlled by
To maintain a constant distance from the magneto-optical disk.
The device can be gravity or inertial depending on its attitude
The magnetic field modulation head and the
The balance with the balancer is always established, and the magnetic field modulation head
Keeps a stable posture with respect to the disk surface.
Improves the earthquake resistance of the recording and playback device, making it extremely suitable for outdoor use
It is suitable.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a magneto-optical disk recording / reproducing apparatus provided with a magnetic field modulation head support mechanism according to the present invention.

FIG. 2 is a partial sectional front view of a magneto-optical disk recording / reproducing apparatus provided with a magnetic field modulation head support mechanism according to the present invention.

FIG. 3 is an exploded perspective view of the contact type magnetic field modulation head support mechanism according to the present invention.

FIG. 4 is a diagram of a disk and a slider for theoretically proving the maximum contact surface radius of the slider.

FIG. 5 is a schematic diagram for proving the balance state of the arm.

FIG. 6 is an exploded perspective view of a non-contact type magnetic field modulation head support mechanism.

FIG. 7 is a sectional view of an assembled state of the non-contact type of FIG. 6;

FIG. 8 is a servo circuit diagram of a non-contact type magnetic field modulation head.

FIG. 9 is a perspective view showing another embodiment of the second arm of the contact type magnetic field modulation head.

FIG. 10 is an exploded perspective view of an arm mechanism showing another embodiment of the arm movable section.

FIG. 11 is an exploded perspective view of an arm mechanism showing still another embodiment of the arm movable section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-optical disk 2 Optical pickup device 2a Attachment part 3 Magnetic field modulation head 4 Turntable 7 Spindle motor 9 Objective lens 12 Arm mechanism 13 First arm 14 Second arm 15 Support plate 16 Spring retainer 17 Arm stopper 18 Elastic displacement Unit 19 Support plate 20 Head core 21 Magnetic field modulation coil 22 Slider 23 Contact surface 25 Balancer 30 Coil spring A Actuator 36 Distance sensor 37 Reference voltage 38 Phase correction circuit 39 Drive amplifier 42 Metal plate 44 Elastic displacement unit 45 Arm support plate 49 Balancer 52 Pivot shaft 54 Balancer 57 Bearing plate 58 Bearing

Claims (3)

(57) [Claims] 1. An optical disk provided on one side of a magneto-optical disk.
Irradiating the magneto-optical disk with a laser beam,
Optical pickup moved in the radial direction of the magnetic disk
Device and the optical pickup device with the magneto-optical disk interposed therebetween
To supply an external magnetic field to the magneto-optical disk.
A field modulation head, the magnetic field modulation head being disposed at one end,
Sliding on the magneto-optical disk surface adjacent to the field modulation head
A sliding portion is provided, and the light is transmitted to the other end via an elastic displacement portion.
A first arm connected to an optical pickup device, and a balancer disposed on the other end side of the first arm
And the optical pickup device together with the first arm.
One end is connected to the first arm and the other end is connected to the magneto-optical device.
A regulation part is provided to regulate the movement of
The second arm and the first arm to the surface of the magneto-optical disk.
A magneto-optical disk, comprising: a biasing member;
Recording and playback device. 2. The device according to claim 1, wherein the urging member is provided on the first arm.
Between the one end and the one end of the second arm.
2. The magneto-optical disc according to claim 1, wherein
Disc recording and playback device. 3. An optical disk provided on one surface of a magneto-optical disk.
Irradiating the magneto-optical disk with a laser beam,
Optical pickup moved in the radial direction of the magnetic disk
Equipment and The optical pickup device sandwiching the magneto-optical disk
To supply an external magnetic field to the magneto-optical disk.
Field modulation head, The magnetic field modulation head is disposed at one end and the other end.
Connected to the optical pickup device via the elastic displacement part
A first arm to be A balancer disposed on the other end side of the first arm
When, Other than the optical pickup device with the first arm
One end is connected, and the other end of the light of the magnetic field modulation head is
A control unit for controlling the distance to the magnetic disk is provided.
With the second arm Magneto-optical disk characterized by having
Disc recording and playback device.