JPH0644322B2 - Magnetic bias generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Field of Industrial Application) The present invention relates to a magnetic bias generator used in a writing device of a magneto-optical disk storage device.

(Prior Art) Problems in the prior art will be described with reference to FIG.

FIG. 3 is a conceptual diagram of a conventional magneto-optical disk storage device, but the magneto-optical disk storage device has the same basic function as that of other magnetic disk storage devices. A magnetic disk on which a thin film is formed is rotated at a constant speed, and a magnetic head arranged close to the magnetic disk magnetizes a magnetic thin film on the magnetic disk to store data, or conversely, on the magnetic disk. The data is read by detecting the voltage of the magnetic head induced by the change in the magnetic flux of the magnetized magnetic thin film.

In the magnetic thin film 100 formed on the surface of the magnetic disk 101 as a storage medium, the area for storing data has a width corresponding to the thickness of the magnetic head (not shown), and the magnetic head is located from the rotation center of the magnetic disk 101. It is well known that a large amount of data can be stored by forming a large number of concentric annular areas: tracks having a radius corresponding to the distance to the stop position.

In the conventional magnetic disk storage device, the track width is narrowed by reducing the thickness of the magnetic head as one means for increasing the storage capacity, and the number of tracks on the surface of the magnetic thin film 100 is increased. However, there is a problem that reducing the thickness of the magnetic head causes a decrease in sensitivity.

A magneto-optical disk storage device was devised to solve this problem and increase the track density.

In FIG. 3C, the magnetic bias generator 105 is attached to the magnetic thin film 100 formed on the surface of the magnetic disk 101.
The magnetic flux 115 from the above acts almost vertically, and the magnetic thin film 1
Magnetic domains 111 indicating magnetic poles are formed on the front and back sides of 00.

The polarity of the magnetic domain 111 follows the bias magnetic flux 115 from the magnetic bias generator.

Further, the light beam 114 from the light beam generator 104 is irradiated so as to focus on the magnetic thin film 100, and the extremely narrow “plane” of the magnetic thin film 100 irradiated by this light beam 114 is It is instantly heated by the thermal energy of the applied light.

By this heating, the magnetic material used for the magnetic disk 101 exceeds the Curie point, and the existing magnetic pole disappears.
It becomes ready to store new data, that is, new data. The magnetic domain 111, which is the “face” where this magnetic pole disappears,
Data is stored by forming a new magnetic pole by the magnetic flux 115 from the magnetic bias generator 105.
The configuration using the light beam 114 can significantly reduce the irradiation width of the condensed light with respect to the critical dimension controlled by the thickness of the conventional magnetic head.
The width of the "plane" on which the magnetism is extinguished by heating, that is, the width of the magnetic domain 111 is small, and therefore the storage capacity can be increased to a greater extent than that of the conventional magnetic disk.

However, in spite of the performance improvement as described above, the practical magneto-optical disk recording device requires the linear motor 106 for moving the magnetic bias generator 105 to the position of the track for performing predetermined data processing. The size of the coil of the magnetic bias generator 105 for generating the bias magnetic flux hinders downsizing of the entire device.

(Problems to be Solved by the Invention) An object of the present invention is to obtain a magnetic bias generator capable of realizing a magneto-optical disk storage device having a simple structure without impairing the storage capacity.

(2) Configuration of the Invention (Means for Solving the Problems) The magnetic bias generator of the present invention is rotatably supported and multi-pole magnetized on its circumference, and at least its length has the magnetic property. A cylindrical permanent magnet corresponding to the size of the entire track width of the disk is connected by a magnetic yoke, and is arranged symmetrically about an axis through a gap formed so that the size of the permanent magnet changes in the rotating direction. And a pair of magnetic pole pieces, and two stator windings are wound around the magnetic yoke, and the two stator windings are energized so that the pair of magnetic pole pieces have the same polarity. ing.

(Operation) In the above-mentioned configuration, it is possible to perform predetermined data processing only by applying a signal to the fixed magnetic bias generator without requiring a linear motor for moving to a predetermined track position. In addition to this, it brings about the effect that the miniaturization of the entire apparatus can be realized.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view for explaining the configuration of an embodiment of the magnetic bias generator according to the present invention and its operation steps. In this embodiment, the outer circumference of the permanent magnet 3 forming the rotor is 4
This is an example of magnetic poles, but as shown in FIG.
When the outer circumferences of the permanent magnets 3 adjacent to -1, 1-1 'are S poles, both of the pole pieces 1-1, 1-1' connected by the magnetic yoke 1-2 are S poles ( When the two stator windings 2 wound around the magnetic yoke 1-2 are excited so as to obtain the display S ′), the S poles of the magnetic pole pieces 1-1 and 1-1 ′ (display: S ′). ) And S on the outer circumference of the permanent magnet 3 facing the
The poles (indication: S ₁ and S ₂ ) repel each other, and the rotatably supported permanent magnet 3 has a CC as shown by the solid arrow in FIG.
Turn to W or CW as indicated by the dashed arrow. In the example of the CCW operation indicated by the solid arrow, the turning operation is the N pole (indication: N) on the outer circumference of the permanent magnet 3, which is located in the middle of both pole pieces 1-1 and 1-1 ′ of FIG. As a result of converting ₁ ) into an S pole (indication: S ₂ ) as shown in FIG. 2B, magnetic irradiation to magnetic heads (not shown, located at the upper portion of FIG. ₂ ) close to the location is performed. The direction of the bias magnetic flux: Φ is reversed, as indicated by the reverse arrow in the arrow. Fig. 1 (b)
In order to re-convert the S pole (indication: S ₁ : S ₂ ) on the outer circumference of the permanent magnet 3 at the intermediate position between the _two pole magnetic pieces 1-1 and 1-1 ′ into the N pole, It suffices if the direction of the exciting current is reversed, and the exciting reversal of the stator winding 2 is caused by the magnetic pole pieces 1-1 and 1-1.
The 1-1 'is converted to the N pole, and the result is in agreement with the initial state (a) in the figure, as shown in the figure (c).

That is, the length that changes the direction of the exciting current of the stator winding 2,
Bias magnetic flux: The direction of Φ can be changed.

Further, as described above, in the above configuration, since the permanent magnet 3 is turned only by changing the direction of the exciting current of the stator winding 2, the turning direction is not stable and is arbitrary. As a means for stabilizing, as shown in FIG. 2, the centers of both magnetic pole pieces 1-1 and 1-1 'may be displaced from each other in the opposite directions with respect to the center of the permanent magnet 3 which is a rotating body (a). Attach the ends of the bipolar magnet pieces 1-1 and 1-1'to the permanent magnet 3
The size of the air gap in the turning direction formed by both pole pieces by means such as (b) which is formed so as to face each other with a gradient.
It may be configured to change g11 and g12.

Further, by setting the length of the permanent magnet 3 to be equal to or larger than the entire track width of the magnetic disk, the permanent magnet 3 simply turns without moving the position of the magnetic bias generator with respect to all the tracks. Arbitrary magnetization processing can be performed only by operation.

(3) Effects of the Invention Since the magnetic bias generator of the present invention has the above-mentioned configuration, the stator winding wound around the magnetic yoke connecting the two magnetic pole pieces facing each other through the air gap to the permanent magnet rotor. A bias magnetic flux of any polarity for the entire track width of the magnetic disk can be obtained simply by switching the energizing direction of the wire, and the movable part is only a rotor with a small mass, so the response is quick and the configuration is simple. Therefore, there is an advantage that the size and weight can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view for explaining an embodiment of a magnetic bias generator according to the present invention and its operation steps. An initial state (a), a bias magnetic flux reversal state due to magnetization of both pole pieces (b) and a magnetic pole are shown. Bias magnetic flux re-inversion by unipolar inversion (c), FIG. 2 is a plan view of an example of stabilizing the turning direction of the permanent magnet according to the present invention, and FIG. 3 is a conventional magneto-optical disk storage. It is a conceptual view of the device and is a plan view (a),
It is a front view (b) and a principal part enlarged view (c). Explanation of symbols 1 ... Stator, 1-1, 1-1 '... Pole piece, 2 ... Stator winding, 3 ... Permanent magnet, 100 ... Magnetic thin film, 101 ... Magnetic disk, 102 ...... Disk drive motor,
103: substrate of the whole device, 104: light beam generator, 10
5 ... Magnetic bias generator, 106 ... Linear motor for moving magnetic bias generator, 111 ... Domain, 114 ... Light beam, 115 ... Bias magnetic flux.

Claims (2)

[Claims] 1. A magnetic bias generator used in a magneto-optical disk storage device, which is rotatably supported, is multi-polarized on its circumference, and has at least an axial length of a magneto-optical disk of the storage device. A cylindrical permanent magnet having a dimension of the entire track width, a pair of magnetic pole pieces connected by a magnetic yoke and symmetrically arranged with respect to the permanent magnet through an air gap, and two magnetic pole pieces wound around the magnetic yoke. Magnetic bias generator for use in a magneto-optical desk storage device, characterized in that the two stator windings are energized so that the pair of magnetic pole pieces have the same polarity. . 2. The structure according to claim 1, wherein the length of the gap formed by the pair of magnetic pole pieces and the cylindrical permanent magnet is changed according to the turning direction. Magnetic bias generator.