JPH0633524Y2 - External magnetic field generator - Google Patents

Description

TECHNICAL FIELD The present invention relates to an external magnetic field generator used for magneto-optical recording, and more particularly to a folding structure of a magnetic pole piece provided for generating a magnetic field.

(Prior Art) In a magneto-optical system, which is a type of optical disk device capable of erasable recording, a magnetic film is heated by a laser spot, a magnetic field of several hundred Oersted is applied to the magnetic film, and the magnetic film is removed when the heating is removed. It uses the principle of being magnetized in the direction of the magnetic field. If the predetermined direction of this magnetization is recording,
The opposite direction is erase.

FIG. 10 is a diagram showing a first configuration example of a conventional external magnetic field generator for implementing the above-mentioned magneto-optical method. In the figure, an external magnetic field generator includes a permanent magnet 2 arranged on a recording magneto-optical disk 1 and an actuator (not shown here) for rotating the permanent magnet 2 about an axis 3 of the permanent magnet 2. For example, a configuration using a magnet etc.)
It has and. The permanent magnet 2 is formed in a rod shape extending in the radial direction of the disk 1, and is magnetized as N and S in the width direction. The component of the magnetic field of this magnet perpendicular to the disk contributes to the magnetic pole reversal of the magnetic film of the disk 1. That is, as shown in the figure, a permanent magnet 2 having magnetic poles S and N arranged in a direction perpendicular to the disk 1
Magnetic recording or erasing is carried out by rotating.

FIG. 11 is a diagram showing a second configuration example of a conventional external magnetic field generator. This external magnetic field generator is mainly composed of an electromagnet 4, as shown in the figure. The electromagnet 4 has an elongated shape, is arranged in the radial direction of the recording magneto-optical disk 1, and has protruding teeth 5, 6a, 6b formed at the lower end thereof. A coil 7 is wound around the center tooth 5, and a current is passed through the coil 7 to generate a magnetic field. The generated magnetic field is generated from the tip of the center tooth 5 to the teeth 6 on both sides.
The components perpendicular to the disk enter a and 6b, and the component perpendicular to the disk serves as an external magnetic field for recording or erasing on the magnetic film. The polarity of the magnetic field is reversed by reversing the direction of current flow.

(Problems to be Solved by the Invention) However, the above-described conventional first and second external magnetic field generators have the following problems, respectively.

In the external magnetic field generator according to the first configuration example, in order to reverse the polarity of the magnetic field, the permanent magnet must be mechanically rotated by some external force, that is, the actuator, and the magnet having a large inertia is rotated. The operating time for the operation requires about 10 to several hundreds [ms], and there are various restrictions in use.

In the second configuration example, the teeth 5 must be lengthened in order to wind the coil 7 of FIG.
It is necessary to make a and 6b the same length as the tooth 5, and there is a disadvantage that the length in the tooth direction becomes long and the entire external magnetic field generator becomes large. And this defect has brought serious obstacles to downsizing and thinning of the magneto-optical disk device.

Therefore, the present invention solves the above problems, and is small and thin,
It is also an object of the present invention to provide an external magnetic field generator having an excellent function.

(Means for Solving the Problems) In order to solve the problems of the prior art, the present invention configures an external magnetic field generator as follows.

According to another aspect of the present invention, there is provided an external magnetic field generator, which includes a magnetic plate, a magnetic pole piece attached to one surface of the magnetic plate, and a magnetic pole piece that is in close contact with the magnetic plate and spreads in the radial direction of the magnetic plate around the magnetic pole piece. And a coil for generating a magnetic field between the magnetic pole piece and the magnetic pole piece by passing an electric current therethrough, the magnetic pole piece being rotatable opposite to the one surface of the magnetic plate. It has a folding mechanism attached to the.

(Operation) According to the present invention, since the external magnetic field generating device is configured as described above, the operation of each technical means is as follows.

When the external magnetic field is generated in the external magnetic field generator according to the present invention, first, the folding mechanism is operated to dispose the magnetic pole pieces substantially perpendicular to the magnetic plate. The coil is wound in a flat shape so as to be in close contact with the magnetic plate and widen in diameter, and the magnetic field generated by energization leaks into the air and enters the magnetic pole piece at the center of the coil and closes. For example, when magneto-optical recording is performed by the device, perpendicular magnetization can be performed using the above-described perpendicular component of the leakage magnetic field (with respect to the magnetic disk).

When changing the direction of the generated magnetic field, the direction of the current flowing through the coil is reversed.

As described above, according to the present invention, the magnetic pole piece is rotatably attached to one surface of the magnetic plate, the coil is wound in a flat shape so as to spread in the radial direction, and the magnetic plate is closely adhered to the external magnetic field generator. The size can be reduced, and the reversal of the magnetic field can be achieved simply by changing the direction of the current. Therefore, the problems of the prior art can be solved.

(Example) Hereinafter, the Example of this invention is described in detail with reference to drawings.

FIG. 1 is a perspective view showing the structure of an external magnetic field generator according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line XX in FIG.

In FIG. 1, an external magnetic field generator comprises a substantially flat magnetic plate 9 and magnetic pole pieces fixed vertically to the lower surface of the magnetic plate 9.
10 and a coil 11 which is closely attached to the lower surface of the magnetic plate 9 with the pole piece 10 as the center and which is spread in the radial direction and wound in a flat shape.
It is configured to include. This external magnetic field generator is arranged on the recording magneto-optical disk 1.

Next, the action of the magnetic field generated by the coil 11 will be described.

As shown in FIG. 2, when a current is passed through the coil 11, a magnetic field is generated from the coil 11. The generated magnetic field leaks into the air through the pole piece 10 and the magnetic plate 9, crosses the disk 1 and the recording surface 1a thereof, and goes out to the outside, and further crosses the recording surface 1a again to the inside from the tip of the pole piece 10. Enter and close. At this time, the magnetic field component perpendicular to the recording surface 1a of the tip portion of the pole piece 10 contributes to the reversal of the magnetization of the recording surface 1a. The leakage magnetic fluxes 12a and 12b from the magnetic plate 9 are, as shown in FIG.
The outer magnetic flux 12a penetrates the outside of the coil and the inner magnetic flux 12b
Penetrates inside.

Here, the above-mentioned operation state will be described in more detail with reference to FIGS. 3 and 4. FIG. 3 shows the cross-sectional area of the coil shown in FIG. 2 from the inside to the outside of the coil 11a, 11b, 11c,
, 11e is a virtual diagram in the case of being divided and considered. FIG. 4 is a diagram showing the magnetic field component 14 with respect to each distance from the center of the pole piece 10 in the longitudinal direction (the vertical axis represents Gauss, the horizontal axis represents the distance). The magnetic field component 14 is, as shown in FIG.
Showing a horizontal component to the pole piece 10 in the vicinity 13 of the tip of 10,
In FIG. 4, the strength of the magnetic field component 14 due to only the coil 11a is 14a, the strength of the magnetic field component 14 due to only the coil 11b is 14b,
Thus, the corresponding magnetic field component 14e up to the coil 11e is shown. It is clear from this graph that the magnetic field component 14 created by each of the coils 11a, 11b, ...
It can be seen that a, 14b, ..., 14e contribute to the magnetic field component 14 with little difference between the inside 11a and the outside 11e of the coil. Therefore, according to the present invention, it is not necessary to wind the coil only around the magnetic pole piece 10 as in the prior art, and even if the coil is flattened and the coil is expanded in the radial direction, the magnetic recording efficiency is not deteriorated. It can exert its performance.

FIG. 5 is a perspective view showing a folding mechanism of the pole piece 10, and FIG.
The drawing is a sectional view taken along the line YY of FIG. In these figures, the same components as those in FIGS. 1 and 2 are designated by the same reference numerals.

As shown in FIG. 5, the folding mechanism includes a bracket 16
a, 16b, a roll 17a, a wire 17, and a solenoid magnet 18 as an electromagnetic drive means. That is, the rotating shaft 15 is provided at the upper ends of both end faces of the magnetic pole piece 10 in the longitudinal direction, and the rotating shaft 15 is rotatably supported by the brackets 16a and 16b. As shown in FIG. 6, one end of a wire 17 is joined to the one end face of the pole piece 10 so as to be separated from the rotary shaft 15, and the other end of the wire 17 is connected to a solenoid magnet 18 via a roll 17a. Are combined. Further, since the magnetic pole piece 10 is held perpendicularly to the magnetic plate 9 and the flat coil 11,
A spring 19 is provided between the shaft 15 and the bracket 16b.

Next, these operations will be described.

In a normal state, the magnetic pole piece 10 is held perpendicularly to the magnetic plate 9 and the coil 11 by the spring 19, and when the solenoid magnet 18 is excited, the wire 17 attached to the upper portion of the magnetic pole piece 10 is pulled, The piece 10 rotates around the rotation axis 15 and falls down, and becomes parallel to the coil 11 as shown by the dotted line in FIG. In this way, the pole piece 10 has a solenoid magnet 18
The folding operation is performed by excitation of.

Next, an example in which the external magnetic field generating device according to the present invention is applied to a magneto-optical disk device is shown in FIGS. 7, 8 and 9. FIG. 7 is a perspective view of a magneto-optical recording device equipped with an external magnetic field generator, and FIGS. 8 and 9 are sectional views taken along line ZZ of FIG. In these figures, inside the magneto-optical disk device 20,
A spindle unit 21 for driving the external magnetic field generator and the magnetic disk is provided. Then, as shown in FIG. 8, the disk cassette 22 accommodating the magnetic disk 1 for recording or erasing data is inserted into the device 20 through the insertion opening (FIG. 8). At the time of this insertion, the solenoid magnet 18 is excited to fold the pole piece 10 through the wire 17 so that the disc cassette 22 does not come into contact with the pole piece 10 and the spindle portion 21 (FIG. 8). When the disc cassette 22 is inserted further into the interior, the disc cassette 22 is lowered by a mechanism (not shown), and the attraction disk 23 in the central hole of the magnetic disk 1 is fitted into the central projection of the spindle portion 21. This completes the insertion of the disc cassette 22.

Next, when performing recording or erasing on the inserted magnetic disk 1, when the excitation of the solenoid magnet 18 is released, the pole piece 10 rises due to the restoring force of the spring 19 and the magnetic plate and the flat coil 11 are removed. Vertical (Fig. 9). That is, an appropriate gap is set at the tip of the pole piece 10 with respect to the recording surface of the magnetic disk 1, and the strength of the magnetic field required for recording or erasing can be obtained (FIGS. 2 and 4).

As described above, when the disc cassette is inserted, the magnetic pole pieces 10 are folded, and when the insertion is completed, the magnetic pole pieces are erected so that the required minimum gap can be secured.

(Effects of the Invention) As described above in detail, according to the present invention, the magnetic pole piece attached to one surface of the magnetic plate and the coil wound in a flat shape so as to spread in the radial direction around the magnetic pole piece are provided. Since an external magnetic field is generated between the magnetic pole pieces by closely contacting the magnetic plate and energizing the coil, it is not necessary to wind the coil only around the magnetic pole pieces as in the conventional case, and it is spread in the radial direction. The device is made thinner by winding it in a flat shape like
Can be miniaturized.

Further, by making the magnetic pole pieces rotatable, the distance between the magnetic pole pieces and the magnetic disk can be selected according to whether or not the external magnetic field generator is used. Therefore, sufficiently excellent performance can be exhibited without lowering the recording efficiency for the magnetic disk.

Further, the direction of the generated magnetic field can be achieved by reversing the direction of the current flowing.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external magnetic field generator for magneto-optical recording according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line XX of FIG. 1, and FIG. 3 is an external magnetic field generation according to this embodiment. FIG. 4 is a diagram for explaining the operation of the device, FIG. 4 is a diagram showing the relationship between the generated magnetic field strength and the distance from the pole piece, FIG. 5 is a perspective view of the folding mechanism, and FIG. 6 is a cross section taken along line YY of FIG. 7 and 7 are perspective views showing that the external magnetic field generator according to the present invention is applied to a magneto-optical disk device, and FIGS. 8 and 9 are sectional views taken along line ZZ of FIG. 7, respectively. The figure which shows the state of the magnetic pole piece at the time of insertion and after the disk insertion, FIG. 10 is the 1st structural example figure of the conventional external magnetic field generator, and FIG. 11 is the 2nd structural example figure of the conventional external magnetic field generator. Is. 1 ... Magnetic disk, 2 ... Permanent magnet 3 ... Shaft, 4 ... Electromagnet 5,6,7 ... Tooth, 9 ... Magnetic plate 10 ... Pole piece, 11 ... Coil 12a, b ... Magnetic flux, 14 ... Magnetic field component 15 ... Rotation axis , 16a, b… Bracket 17… Wire, 18… Solenoid electrode 19… Spring

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuo Shimizu 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (56) Reference JP 61-137201 (JP, A) JP Sho 62-172504 (JP, A)

Claims (2)

[Scope of utility model registration request] 1. A magnetic plate, a magnetic pole piece attached to one surface of the magnetic plate, and a flat shape which is in close contact with the one surface of the magnetic plate and spreads in the radial direction of the magnetic plate with the magnetic pole piece as a center. An external magnetic field generator comprising: a coil wound around the magnetic pole piece and generating a magnetic field between the magnetic pole piece and the magnetic pole piece by energizing a current, wherein the magnetic pole piece is rotatably attached to face the one surface of the magnetic plate. An external magnetic field generator having a folding mechanism. 2. The utility model registration, wherein the folding mechanism includes electromagnetic driving means for rotating the magnetic pole piece so as to fix the magnetic pole piece at a position substantially perpendicular to the one surface of the magnetic plate. The external magnetic field generator according to claim 1.