JPH0610841B2 - 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) FIG. 4 is a conceptual diagram of a conventional magneto-optical disk storage device. The basic function of the magneto-optical disk storage device is the same as that of other magnetic disk storage devices. A magnetic disk having a magnetic thin film formed on its surface is rotated at a constant speed, and a magnetic head arranged close to the magnetic disk magnetizes the magnetic thin film on the magnetic disk to store data, or vice versa. 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 on the magnetic disk.

In the magnetic thin film 100 formed on the surface of the magnetic disk 101 as a storage medium, an area for storing data has a width corresponding to the thickness of a 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 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. Fig. 4
In (c), the magnetic flux 11 from the magnetic bias generator 105 is applied to the magnetic thin film 100 formed on the surface of the magnetic disk 101.
5 acts almost vertically to form magnetic domains 111 indicating magnetic poles on the front and back surfaces of the magnetic thin film 100.

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'face '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.

With this heating, the existing magnetic pole disappears when the magnetic material used for the magnetic disk 101 exceeds the Curie point,
It becomes ready to store new data, that is, new data.

The magnetic domain 111, which is the “face” where the magnetic pole disappears, stores data 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 regulated by the thickness of the conventional magnetic head.
The width of the “face” where 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 storage device requires the linear motor 106 for moving the magnetic bias generator 105 to the position of the track for performing predetermined data processing. However, there is a problem that 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 by a pair, and a pair of them that are adjacent to each other at an angle of approximately 120 degrees on the circumference are almost Cylindrical permanent magnets having a length of at least equivalent to the entire track width of the magnetic disk magnetized on four alternating poles consisting of a pair of adjacent magnets at 60 degrees, and the permanent magnets having the lengths described above. A pair of magnetic pole pieces whose one ends are symmetrically arranged about the axis so as to face the permanent magnet with a gap in about half of the above, and are connected by a magnetic yoke, and a stator winding wound around the magnetic yoke. And a structure similar to that of the first stator, in which each pair of magnetic pole pieces has a pair of outer end portions with respect to each magnetic pole piece of the first stator. The second fixing, which is located at an elevation angle of about 120 degrees and is adjacent to and axially insulated And a magnetic flux of the permanent magnet projected into a space provided in a direction substantially perpendicular to the pair of magnetic poles of the first stator and the second stator. It is characterized in that it is used as a magnetic flux for a magnetic field. By alternately energizing the windings of the two stators, the permanent magnet is rotated to switch the polarity of the magnetic flux for biasing, thereby achieving the object. is there.

(Operation) In the above-mentioned configuration, the magnetic bias generator is moved to a predetermined track position because the length of the permanent magnet that generates the magnetic flux for bias covers the entire track width of the magnetic disk. Does not need a linear motor to
Electric power for exciting the coil is not required, and a predetermined data processing can be performed only by applying a signal to a fixed magnetic bias generator.

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

FIG. 1 is a partial sectional view (a) and an AA ′ sectional view (b) of a magnetic bias generator according to the present invention. As shown in FIG. 1, the first stator 1 and the second stator 2 are A pair of magnetic pole pieces 5, 6 and 9, 10 which are adjacent to each other in the axial direction and are insulated from each other and are connected by magnetic yokes 3, 4 are provided in one permanent magnet rotor 15 with a small air gap. Are arranged at positions symmetrical with respect to the respective outer ends.

The pole pieces forming each pair of the above-mentioned two stators include a side having a large arc angle of the first (second) stator and a side having a small arc angle of the second (first) stator. However, the stator windings 7, 8 and 1 which are arranged around the respective magnetic yokes 3 and 4 are arranged so that the elevation angles formed by their outer ends are approximately 120 degrees.
1,12 are electrically connected to each other, so they are simultaneously energized,
It is configured to generate magnetic fluxes having different polarities on both sides.

The rotor is composed of a shaft 14 and a cylindrical permanent magnet 15 integrally fixed thereto, and is rotatably supported by a bearing 13.

The cylindrical permanent magnet 15 has two stators, that is, two stators, as described above.
The pole pieces 5, 6 and 9, 10 forming a pair are opposed to each other, but their lengths are substantially equal to or slightly longer than the entire track width of the magnetic disk, and their directions are substantially orthogonal to the tracks of the magnetic disk. It is arranged as follows.

FIG. 2 is a partially enlarged view for explaining the relationship between the magnetic pole pieces 5, 6 and 9, 10 of FIG. 1 and the cylindrical permanent magnet 15 of the rotor facing the magnetic pole pieces. It is magnetized into four alternating poles of a pair of degrees and a pair of 60 degrees. Further, FIG. 2 shows a pair of magnetic pole pieces 5 of the first stator 1 and the second stator 2, respectively.
6 and 9, 10 are shown in the same plane for convenience.

In the partially enlarged view shown in FIG. 2, the arc angles of the surfaces of the magnetic pole pieces 6, 9 and 5, 10 facing the permanent magnet 15 are almost the same.
At 90 degrees and 45 degrees, the elevation angle when viewed from the axis of the outer end of each of the pole pieces 5, 9 and 6, 10 is approximately 120 degrees, and the apparent appearance of the pole pieces 5 and 9 or 6 and 10 in plan view. The elevation angle viewed from the axis of the intersecting portion is approximately 15 degrees, and the elevation angle in the space portion between 5 and 10 and 6 and 9 is approximately 60. FIG. 3 is an explanatory view of the operation of the magnetic bias generator according to the present invention. The stop position of the permanent magnet 15 shown in FIG. 3 (1) is the stator winding wound on the second stator 2 side. 11, 12 are energized, and the pole piece 9 is the same as the N pole 1
It shows the state of being excited so that 0 becomes the S pole, and the permanent magnet 15
The S pole magnetized at 120 degrees is attracted to the N pole of the magnetic pole piece 9, and the N pole of the permanent magnet 15 is attracted to the S pole of the magnetic pole piece 10 to form the central portion of the space between the magnetic pole pieces 9 and 6. The N pole of the permanent magnet 15 faces each other, that is, the bias magnetic flux Φ shows the N pole.

Next, in FIG. 6B, immediately after the stator windings 11 and 12 are released and the other stator windings 7 and 8 are excited so that the pole pieces 5 and 6 become the N pole and the S pole, respectively. As shown by the arrow in the figure, the S pole (120 degree magnetization) of the permanent magnet 15 attracted to the magnetic pole piece 9 is released from the magnetic pole piece 9 and attracted to the magnetic pole piece 5.
Further, since the N (half of 120-degree magnetization) and the S pole (60-degree magnetization) located 180 degrees opposite to each other are attracted or repelled by the (S pole) of the pole piece 6, the permanent magnet 15 is the same. As shown in Figure (c), it rotates about 60 degrees counterclockwise and stops at equilibrium, that is, the bias magnetic flux is converted to the south pole. In order to convert the magnetic bias from the S pole to the N pole, the first stator 1 is released and the second stator 2 is excited to magnetize the pole pieces 9 and 10 to the N pole and the S pole, respectively. By doing so, the permanent magnet rotor 15 can be reached by rotating it counterclockwise and returning to the state of FIG.

The magnetic bias generator according to the present invention shown in FIG. 1 corresponds to the magnetic bias generator 105 of the magneto-optical disk storage device in the conventional structure shown in FIG.
The magnetic disk 101 is arranged close to the magnetic flux Φ shown in the arrow direction.

A magnetic disk 10 that faces the magnetic flux Φ at right angles.
As shown in Fig. 3 (c), the magnetic thin film 10 is formed on the surface of 1 as before.
0 is formed to form the track surface of the magneto-optical disk storage device.

Then, by changing the magnetic pole of the permanent magnet 15 as described above, the magnetic domain demagnetized by the light beam is arbitrarily magnetized to write data.

Further, by setting the length of the permanent magnet 15 to be equal to or larger than the entire track width of the magnetic disk, without moving the position of the magnetic bias generator with respect to all the tracks,
Arbitrary magnetization processing can be performed by simply rotating the permanent magnet 15.

(3) Effect of the Invention Since the magnetic bias generator used in the magneto-optical disk storage device according to the present invention has the above-described structure, the windings of each of the two stators provided side by side are alternately excited. Since it is possible to obtain a bias magnetic flux for the entire track width of the magnetic disk, it is not necessary to provide a linear motor for moving the entire magnetic bias generator in the direction perpendicular to the tracks as in the conventional magnetic bias generator, and the response is fast and the entire device In addition to realizing the miniaturization, it is possible to construct a magneto-optical disk storage device that does not require electric power for exciting the coil for generating bias magnetic flux.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view (a) and an AA ′ cross-sectional view (b) showing an example of the present invention, and FIG. 2 is a partial enlarged view showing the correlation between the rotor and a pole piece directly opposed thereto. FIG. 3 is an explanatory view showing the rotating state of the rotor due to the magnetization of the pole pieces, and FIG. 4 is a conceptual view of a conventional magneto-optical disk storage device, which is a plan view (a) and a front view ( b) and an enlarged view of the main part (c). Explanation of reference numerals 1, 2: stator, 3, 4: magnetic yoke, 5, 6, 9 and 10: magnetic pole pieces 7, 8, 11 and 12: stator winding 14: rotating shaft 15: permanent magnet, 100: Magnetic thin film 101: magnetic disk, 102: electric motor for driving disk, 103: substrate of the entire device, 104: light beam generator 105: magnetic bias generator, 106: linear motor for moving magnetic bias generator, 111: magnetic domain 114: light beam, 115: bias magnetic flux.

Claims (2)

[Claims] 1. A magnetic bias generator for use in a magneto-optical disk storage device, wherein a pair of rotatably supported shafts, which are adjacent to each other at an angle of approximately 120 degrees, are approximately 60 degrees, respectively.
Cylindrical permanent magnets, which are alternately magnetized to have four poles, form a pair adjacent to each other at a degree, each length corresponding to at least the dimension of the entire track width of the magnetic disk, and the length thereof is equal to the above-mentioned value. A pair of first magnetic pole pieces, one end of which is symmetrically arranged with respect to the axis so as to face the permanent magnet with a gap in approximately half of the permanent magnet and are connected by a first magnetic yoke, and the magnetic yoke. A first stator composed of a wound first stator winding, and a length of the first stator that is substantially equal to that of the first stator and opposed to the permanent magnet with a gap therebetween. A pair of second magnetic pole pieces whose one ends are arranged symmetrically with respect to an axis and which are connected by a second magnetic yoke, and a second stator winding wound around the second magnetic pole pieces are provided. The second magnetic pole pieces forming the pair of first magnetic pole pieces each have an elevation angle formed between their outer ends with respect to each of the pair of first magnetic pole pieces. Magnetic bias generator for use crucible magneto-optical disk storage device, wherein more composed that a second stator disposed adjacent insulation to the position in an axial direction is 120 degrees. 2. The arc angle of the magnetic pole piece is formed such that one of the two stators is in the range of 70 degrees to 110 degrees and the other is in the range of 35 degrees to 55 degrees. The magnetic bias generator according to claim 1.