JPH0568761B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an external magnetic field generating device used for magneto-optical recording, and particularly to a folding structure of magnetic pole pieces provided for generating a magnetic field.

(Prior art) In the magneto-optical method, which is a type of optical disk device capable of erasable recording, a magnetic film is heated with a laser spot, a magnetic field of several hundred oersted is applied thereto, and when the heating is removed, the magnetic film disappears. It uses the principle that magnetization occurs in the direction of an external magnetic field. If a predetermined direction of this magnetization is used for recording, the opposite direction is used for erasing.

FIG. 6 is a diagram showing a first configuration example of a conventional external magnetic field generating device for implementing the magneto-optical method. In the figure, the external magnetic field generator is a permanent magnet 2 placed on a recording magneto-optical disk 1.
and an actuator (for example, a configuration using a magnet or the like) that rotates the permanent magnet 2 around an axis 3 in the longitudinal direction of the permanent magnet 2, although not shown here. The permanent magnet 2 is formed into a bar shape extending in the radial direction of the disk 1, and is magnetized in N and S directions 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, disk 1
A permanent magnet 2 with magnetic poles S and N arranged perpendicularly to the
Magnetic recording or erasure is performed by rotating it 180 degrees.

FIG. 7 is a diagram showing a second configuration example of a conventional external magnetic field generator. This external magnetic field generator mainly consists of an electromagnet 4 as shown in the figure. The electromagnet 4 has an elongated shape, is arranged in the radial direction of the magneto-optical recording disk 1, and has protruding teeth 5, 6a, 6b formed at its lower end. A coil 7 is wound around the central tooth 5, and a magnetic field is generated by passing a current through the coil 7. The generated magnetic field enters the teeth 6a, 6b on both sides from the tip of the central tooth 5, and the component perpendicular to the disk becomes an external magnetic field to perform 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-mentioned conventional first and second external magnetic field generating devices each have the following problems.

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, an actuator, and the magnet with large inertia must be rotated. The operating time required to do this was about ten to several hundred milliseconds, and there were various restrictions on use.

Furthermore, in the second configuration example, in order to wind the coil 7 shown in FIG. 7 the required number of times, the teeth 5 must be made longer.
Further, the teeth 6a and 6b on both sides must have the same length as the tooth 5, which has the disadvantage that the length in the tooth direction becomes longer and the entire external magnetic field generator becomes larger.
This drawback poses a serious obstacle to miniaturization and thinning of magneto-optical disk devices.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an external magnetic field generating device that is small and thin and has excellent functionality.

(Means for Solving the Problems) In order to solve the above problems, the external magnetic field generating device of the present invention includes (a) a magnetic plate, (b) a magnetic pole piece rotatably provided on one surface of the magnetic plate. , (c) a coil that is closely attached to one surface of the magnetic plate, spread radially around the magnetic pole piece and wound in a flat shape, and generates a magnetic field between it and the magnetic pole piece when energized; (d) (e) an elastic member that holds the magnetic pole piece at a predetermined angle with respect to one surface of the magnetic plate; and (e) provided at an end of the magnetic pole piece;
The guide plate includes a guide plate that rotates the magnetic pole pieces so as to be parallel to the one surface when a horizontal force larger than the holding force of the elastic member is applied to one surface of the magnetic plate.

(Function) According to the present invention, since the external magnetic field generating device is configured as described above, the technical means functions as follows. When a magnetic field is generated, the magnetic pole piece is held open at a predetermined angle (for example, about 45° to 60°) with respect to one surface of the magnetic plate by an elastic member (for example, a spring). In this state, by energizing the coil wound flat around the magnetic pole piece, the magnetic field generated from the coil passes through the air and closes through the magnetic pole piece and the magnetic plate. Therefore, for example, when performing magneto-optical recording with this device,
Perpendicular magnetization can be achieved using the perpendicular component of the magnetic field. On the other hand, when no magnetic field is generated, the pole piece is exposed to a force applied to the end of the guide plate in a horizontal direction (relative to one side of the magnetic plate) that is greater than the holding force of the elastic member, or When a vertical force is applied to the magnetic plate (including the plate surface), it rotates and folds parallel to one side of the magnetic plate. For example, if this device is applied to a magneto-optical disk device and the device is installed on top of the magneto-optical disk device, the magnetic pole piece will close via the guide plate by horizontally inserting the disk cassette. When the disk cassette is lowered, it is opened and a magnetic field is generated. The opposite is true when ejecting a disk cassette. In this way, by winding the coil in a flat shape around the magnetic pole piece on the magnetic plate, it is possible to realize a small and thin external magnetic field generator without reducing efficiency, and also to reduce the magnetic field. Since the structure is such that the magnetic pole piece is folded against the magnetic plate via the guide plate when no generation occurs, the magnetic pole piece can be easily set and reset, and an inexpensive external magnetic field device can be realized.

(Example) An example of the present invention will be described with reference to FIGS. 1 to 5.

2A and 2B are basic configuration diagrams of an external magnetic field generating device showing the principle of this embodiment, in which FIG. 2A is a perspective view and FIG. 2B is a cross-sectional view taken along line X-X' in FIG.

In FIG. 2a, the external magnetic field generating device includes a substantially flat magnetic plate 9, a magnetic pole piece 10 provided perpendicularly to the lower surface of the magnetic plate 9, and a magnetic pole piece 10 provided on the lower surface of the magnetic plate 9 with the magnetic pole piece 10 at the center. The coil 11 is configured to include a coil 11 that is tightly wound in a flat shape and spread in the radial direction. This external magnetic field generator is arranged on the magneto-optical disk 1 for recording.

Next, the operation will be explained.

As shown in FIG. 2b, 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 magnetic pole piece 10 and the magnetic plate 9, and damages the magneto-optical disk 1 and its recording surface 1a.
The magnetic pole piece 10 is crossed and exited to the outside, and then the recording surface 1a is crossed again and entered from the tip of the magnetic pole piece 10 to the inside and closed. At this time, a magnetic field component perpendicular to the recording surface 1a in the tip portion of the magnetic pole piece 10 contributes to reversal of the magnetization of the recording surface 1a. Regarding the leakage magnetic fluxes 12a and 12b from the magnetic plate 9, as shown in FIG. 2b, the outer magnetic flux 12a passes through the outside of the coil, and the inner magnetic flux 12b passes through the inside.

Here, the above-mentioned operating state will be explained in more detail with reference to FIGS. 3 and 4. FIG. 3 shows the cross-sectional areas of the coil shown in FIG.
This is a hypothetical diagram when considering dividing into two parts. FIG. 4 is a diagram showing the magnetic field component 14 for each distance from the center of the magnetic pole piece 10 in the longitudinal direction (the vertical axis shows Gauss, and the horizontal axis shows the distance). As shown in FIG. 3, the magnetic field component 14 is defined as
In FIG. 4, the strength of the magnetic field component 14 due only to the coil 11a is indicated by 14a, the strength of the magnetic field component 14 due to only the coil 11b is indicated by 14b, and so on.
The corresponding magnetic field component 14e up to 14 is shown. What is clear from this graph is that the magnetic field components 14a, 14b, ..., 14e generated by each of the coils 11a, 11b, ..., 11e, which are considered separately, are:
It can be seen that both the inner side 11a and the outer side 11e of the coil contribute to the magnetic field component 14 without much difference. Therefore, according to the present invention, it is not necessary to wind the coil only around the magnetic pole piece 10 as in the conventional case, and even if the coil is wound in a flat shape and spread out in the radial direction, it is sufficient to do so without reducing the magnetic recording efficiency. performance can be demonstrated.

Next, an embodiment will be described in which the magnetic pole piece 10 in the basic configuration of the external magnetic field generator described above is foldable with respect to the magnetic plate 9.

Figures 1a, b, and c are configuration diagrams of an external magnetic field generating device showing one embodiment of the present invention, in which figure a is a perspective view, and figures b and c are X-X' in figure a, respectively. It is a sectional view and a YY' sectional view. In the same figure, the second
The same reference numbers as in the figures indicate identical components. 15 is a shaft provided at both ends of the magnetic pole piece 10 and serves as the center of rotation; 16a and 16b are brackets that rotatably support the shaft 15; and 17 is a shaft that supports the magnetic pole piece 10 with respect to the surface of the magnetic pole plate 9 and the coil 11. Spring holding at a predetermined angle, 18a, 18
b is a guide plate provided at both ends of the magnetic pole piece 10.

Next, the operation of this embodiment will be explained.

First, in a normal state, that is, when no force is applied to the magnetic pole piece 10 and the guide plates 18a, 18b, the spring 17 causes the magnetic pole piece 10 and the guide plates 18a, 18b to be pressed against the surface of the magnetic plate 9 and the coil 11. It is in an open state at an angle of about 45° to 60° (Fig. 1b). In this state, as shown in FIG. 1b, when a force f ₁ perpendicular to the surfaces of the magnetic plate 9 and the coil 11 is applied, the magnetic pole piece 10 rotates in the direction of the arrow, and the magnetic plate 9 is parallel to the plane of the coil 11, and is folded inside the center of the coil 11. When the force f ₁ is removed, the magnetic pole piece 10 returns to its original position due to the holding force of the spring 17.

In the normal state, as shown in FIG. 1c, when a horizontal force f ₂ is applied to the ends (hypotenuses) of the guide plates 18a, 18b, the pole pieces 10 are similarly rotated and folded.

Next, an example in which the external magnetic field generating device of this embodiment is applied to a magneto-optical disk device is shown in FIG.
This will be explained with reference to b and c. Figure a is a perspective view of a magneto-optical disk device equipped with an external magnetic field generator;
Figures b and c show cross-sectional views taken along the Z-Z' line in figure a. Inside the magneto-optical disk device 20, an external magnetic field generator 100 is attached to the upper part, and a spindle section 21 for rotationally driving the magneto-optical disk is provided in the center. In order to record or erase data, a disk cassette 22 containing a magneto-optical disk 1 is inserted through an insertion slot 23. This insertion port 23 is provided above the side surface of the device 20 so that the disk cassette 23 does not come into contact with the tip of the spindle portion 22. Insertion port 23
The tip of the disk cassette 22 inserted from
Of the guide plates 18a, 18b attached to both ends of the magnetic pole piece 10, the magnetic pole piece 10 and the guide plates 18a, 1 are in contact with the inclined end of the guide plate 18b on the inlet side.
Push up 8b and proceed (Figure 5b). The magnetic pole piece 10 and guide plates 18a, 18b remain pushed up until the disk cassette 22 is inserted completely to the back. Next, the disk cassette 22 is lowered by a mechanism not shown, and the suction disk 22a and the spindle part 21 are fitted together. At the time of this lowering, the magnetic pole piece 10 and the guide plates 18a, 18b are attached to the disk cassette 22. The magnetic pole piece 10 gradually opens as it descends while contacting the upper part of the magnetic pole piece 10, and slightly before the suction disk 22a is completely fitted into the spindle part 21, the magnetic pole piece 10 is completely opened while maintaining an angle of 45° to 60°. End, magneto-optical deix 1
The required gap between the surface of the magnetic pole piece 10 and the tip of the magnetic pole piece 10 is set, and the strength of the magnetic field necessary for recording is set at the recording surface 1.
a (Fig. 5c). Next, in the ejection operation, the disk cassette 22 first rises, but at this time, the magnetic pole piece 10 and the guide plate 18
Since a and 18b are attached at an angle of 45° to 60°, they can be easily folded even if pushed up vertically from below. Thereafter, the disk cassette 22 reaches the insertion port in the reverse operation while pushing aside the magnetic pole piece 10 and the guide plates 18a, 18b in the same manner as during insertion.

In this way, in this embodiment, the disk cassette 2
2 is the magnetic pole piece 10 and the guide plates 18a, 18
When the magneto-optical disk 1 is set in the proper position where recording/reading is possible, the magnetic pole piece 10 is also set, and conversely, when ejecting, the magnetic pole piece 10 and the guide plates 18a, 18b are also set.
The magnetic pole piece 10 is set only when necessary by pushing the magnetic pole piece 10 away.

(Effects of the Invention) As described in detail above, according to the present invention, the coil is wound flatly around the magnetic pole piece on the magnetic plate, so it is small and thin without reducing efficiency. It can be shaped. Furthermore, since the magnetic pole pieces are folded against the magnetic plate via the guide plate, the magnetic pole pieces can be easily set only when needed, and the device can be made inexpensive.

Furthermore, when this device is applied to a magneto-optical disk device, the magnetic pole piece can be folded without requiring any other power by pushing the cassette away from the guide plate when inserting and ejecting the disk cassette. Therefore, a magneto-optical disk device can be provided at low cost.

[Brief explanation of the drawing]

Figures 1a, b, and c are block diagrams of one embodiment of the present invention, Figures 2a and b are basic configuration diagrams showing the principle of this embodiment, and Figure 3 is an explanatory diagram of the operation of Figure 2; Figure 4 is a diagram of the relationship between magnetic field components and distance, Figures 5 a, b, and c are explanatory diagrams of examples of adaptation of external magnetic field generators, Figure 6 is a diagram of a conventional first configuration example, and Figure 7 is a diagram of a conventional configuration. FIG. 2 is a second configuration example diagram. 1... Magnetic disk, 9... Magnetic plate, 10...
Magnetic pole piece, 11... Coil, 12a, 12b... Magnetic flux, 14... Magnetic field component, 15... Shaft, 16
a, 16b...bracket, 17...spring, 18a, 18b...guide plate, 20...
... Magneto-optical disk, 21 ... Spindle part, 22
...Disc cassette, 22a...Suction disk, 2
3...Insertion/ejection port, 100...External magnetic field generator.

Claims (1)

[Scope of Claims] 1 (a) a magnetic plate; (b) a magnetic pole piece rotatably provided on one surface of the magnetic plate; (c) a magnetic pole piece that is closely attached to one surface of the magnetic plate and has a diameter centered on the magnetic pole piece; It spreads in the direction and is wound into a flat shape,
a coil that generates a magnetic field between it and the magnetic pole piece when energized; (d) an elastic member that holds the magnetic pole piece at a predetermined angle with respect to one surface of the magnetic plate; , a guide plate that rotates a magnetic pole piece so that it is parallel to one surface of the magnetic plate when a horizontal force larger than the holding force of the elastic member is applied to one surface of the magnetic plate. External magnetic field generator.