JPS63292402A - External magnetic field generating device - Google Patents

Abstract

PURPOSE:To miniaturize and thin the titled device, and also, to facilitate to set and reset a magnetic pole piece by providing a coil which has been wound flatly centering around the magnetic pole piece on a magnetic plate, and the magnetic pole piece of a structure to be folded against the magnetic plate. CONSTITUTION:The titled device is formed by a magnetic pole plate 9 of a roughly flat shape and a magnetic pole piece 10 provided vertically on its lower face, and a coil which adheres closely onto the lower face of the magnetic pole piece 9 centering around the magnetic pole piece, expands in the diameter direction and wound flatly, and placed on a magneto-optical disk for recording. The magnetic pole piece 10 ad guide plates 18a, 18b become a state opened at an angle of about 45 deg.-60 deg. against the magnetic plate 9 and the surface of the coil 11 by a spring 17, in the case of a usual state, and when force f1 in the vertical direction or force f2 in the horizontal direction is applied to the magnetic plate 9, the magnetic pole piece 10 is folded to the inside of the coil 11, and can be set easily when necessary.

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 -IPh for optical disk devices capable of erasable recording, a magnetic layer is heated with a laser spot, a magnetic field of several hundred oersted is applied thereto, and when the heating is removed, the magnetic It uses the principle that the film is magnetized 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 includes a permanent magnet 2 disposed on a recording magneto-optical disk 1, and a permanent magnet 2 centered on a longitudinal axis 3 of the permanent magnet 2 (not shown here).
The actuator (for example, using a magnet or the like) rotates the actuator. Permanent magnet 2 is disk 1
It is formed into a rod shape extending in the radial direction of [N in the 1J direction,
It is magnetized with S. 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, magnetic recording or erasing is performed by rotating a permanent magnet 2 having magnetic poles S and N arranged perpendicularly to the disk 1 by 180 degrees around a shaft 3 using an actuator as shown in the figure.

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 and is arranged in the radial direction of the magneto-optical recording disk 1, and has protruding south 5, 6a, 6b at its lower end.
is formed. A coil 7 is wound around the center ring 5, and a magnetic field is generated by passing a current through the coil 7. The generated magnetic field enters /Jj6a, 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 record or erase 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 first and second conventional external magnetic field generating devices described above 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 1 to several hundred milliseconds, and there were various limitations on the amount of work that could be used.

In addition, in the second configuration example, in order to wind the coil 7 shown in FIG.
It is necessary that a and 6b have the same length as the tooth 5, which has the disadvantage that the length in the tooth direction becomes long and the entire external magnetic field generating device becomes large. This drawback poses a serious obstacle to miniaturization and thinning of magneto-optical disk devices.

Therefore, the present invention solves the above problems and provides a small and thin
Our aim is to provide an external magnetic field generator with 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 rotating
4. Magnetic pole pieces provided in the fourth function, (c) -o'i of the magnetic plate mentioned above.
(d) a coil that is in close contact with the magnetic pole piece, spreads radially around the magnetic pole piece, and is wound in a flat/T shape, and generates a magnetic field between the magnetic pole piece and the magnetic pole piece when energized; (e) an elastic member that holds the plate at a predetermined angle with respect to one surface of the magnetic plate; The device is equipped with a guide plate that rotates the magnetic pole pieces so that when a force is applied, the magnetic pole pieces are aligned with the - plane.

(Function) According to the present invention, since the external magnetic field generating device is configured as described below, the technical means functions as follows. When a magnetic field is generated, the magnetic pole pieces are rotated at a predetermined angle (for example, 45
60°) and placed in the open position.

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 via the pole piece &Ii and the magnetic plate. Therefore, for example, when performing magneto-optical recording with this apparatus, perpendicular magnetization can be performed using the perpendicular component of the magnetic field. on the other hand,
In the absence of a magnetic field, the pole pieces are either 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
It is rotated and folded so that it is parallel to one side of the magnetic plate. For example, when this device is applied to a magneto-optical disk device, if the device is installed on the top of the magneto-optical disk device, the magnetic pole pieces can be moved through the guide plate by inserting the disk cassette in the direction of the water flow. It is closed and folded, and when the disk cassette is lowered, it opens to generate a magnetic field. When ejecting a disk cassette, this is the opposite. in this way,
Since the coil is wound flat 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 when no magnetic field is generated, Since the magnetic pole pieces are folded against the magnetic plate via the guide plate, it is easy to set and reset the magnetic pole pieces, and an inexpensive external magnetic field device can be realized.

(Example) The present invention will be described in detail with reference to FIGS. 1 to 5.

FIGS. 2(a) and 2(b) are basic configuration diagrams of an external magnetic field generator showing the principle of this embodiment, in which FIG. 2(a) is a perspective view and FIG. 2(b) is a perspective view. FIG.

In Fig. 2(a), the external magnetic field generator is
An upper-shaped magnetic plate 9, a magnetic pole piece lO provided perpendicularly to the lower surface of the magnetic plate 9, and a magnetic plate 9 centered around the magnetic pole piece 10.
The coil is closely attached to the lower surface of the coil, spread in the radial direction, and wound into a flat shape. This external magnetic field generator is arranged on a magneto-optical disk l for recording.

Next, the operation will be explained.

As shown in FIG. 2(b), when a current is passed through the coil +1, a magnetic field is generated from the coil 11. The generated magnetic field leaks into the air through the magnetic pole piece lO and the magnetic plate 9, crosses the magneto-optical disk 1 and its recording surface 1a, exits to the outside, crosses the recording surface 1a again, and exits from the tip of the magnetic pole piece 10. Go inside and close. At this time, the magnetic field component perpendicular to the recording surface Ia at the tip of the magnetic pole piece IO is
Close to reversal of magnetization of a! j, do it. As shown in FIG. 2(b), the leakage magnetic fluxes 12a and 12b from the magnetic plate 9 are such that the outer magnetic flux 12a penetrates the outside of the coil, and the inner magnetic flux 1
2b passes v1 inside.

Here, the operating state described above will be explained in more detail with reference to FIGS. 3 and 4. Figure 3 shows the cross-sectional area of the coil shown in Figure 2 from the inside of the coil to the outside.
This is a virtual diagram when considering the case of dividing into lb, llc, -, and lie. FIG. 4 is a diagram showing the magnetic field component 14 for each distance from the center of the magnetic pole piece IO in the longitudinal direction (vertical axis is Gauss, horizontal axis represents 11" recording distance). As shown in the figure, a component below the magnetic pole piece 10 near the tip 13 of the magnetic pole piece !O is shown, and in FIG. 14b, and so on, the corresponding magnetic field component up to the coil Ite is 14e.
It shows. What is clear from this graph is the magnetic field component t4a generated by each of the divided coils Ila, llb, -, ltc.

14b, -j4c are both inside 11a and outside 1 of the coil.
It can be seen that even 1c contributes to the magnetic field component 14 without making much of a 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, the magnetic recording efficiency will not be reduced. Performance can be demonstrated in 1 minute.

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

FIGS. 1(a), 1(b), and 1(c) are configuration diagrams of an external magnetic field generator showing an embodiment of the present invention, and FIGS.
FIG. 11A is a perspective view, and FIGS. 12B and 20C are sectional views taken along line X-X' and Y-Y' in FIG. In this figure, the same reference numerals as in FIG. 2 indicate the same components. 15 are provided at both ends of the magnetic pole piece 10,
The shafts 16a and 16b are the shafts 1 that are the center of rotation.
A bracket 17 rotatably supports the Mi pole piece 1.
0 at a predetermined angle with respect to the plane of the magnetic pole plate 9 and the coil 11, 18a, 18b GEL magnetic pole piece I
This is a guide plate provided at both ends of the O.

Next, the operation of this embodiment will be explained.

First, in the normal state, that is, when no force is applied to the magnetic pole piece IO and the guide plates 18a, 1 (lb), the spring 17 causes the IIae piece IO 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 with an angle of about 45° to 60° to the other side [Fig. 1 (b)]. In this state, as shown in Figure 1 (
As shown in b), when an eastward force f1 is applied to the surface of the magnetic plate 9 and the coil It, the magnetic pole piece! 0 rotates in the direction of the arrow, becomes parallel to the magnetic plate 9, and is folded inside the center of the coil 11. When the force f1 is removed, the magnetic pole piece lO returns to its original position by the holding force of the spring 17.

In the normal state, as shown in FIG. 1(c), when water NV and force f2 in the direction are applied to the ends (hytenuse parts) of the guide plates +8a and 18b, the magnetic pole pieces 10 are similarly rotated and folded. .

Next, FIG. 5(a) shows an example in which the external magnetic field generating device of this embodiment is applied to a magneto-optical disk device.

This will be explained with reference to (b) and (c). FIG. 5(a) is a perspective view of a magneto-optical disk device equipped with an external magnetic field generating device, and FIG. Inside the magneto-optical disk device 20, an external magnetic field generator +00 is attached to the L section,
At the center is a spindle unit 2 that rotates the magneto-optical disk! is provided. A disk cassette 2 containing a magneto-optical disk 1 for recording or erasing data.
2 is inserted from the insertion port 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 section 22.

The tip of the disk cassette 2z inserted through the insertion [123] is the guide plate 18a attached to both ends of the magnetic pole piece IQ.

While contacting the inclined end of the guide plate 18b on the side 18b, the magnetic pole piece IO pushes up the guide plates 18a and 18b and advances (Fig. 5(b)
)). The magnetic pole piece IO and guide plates 18a and +8b 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
During this downward movement, the magnetic pole piece 10 and the guide plates 18a and 18b gradually open as they descend while contacting the F section of the disk cassette 22, and the magnetic pole piece 10 and the guide plates 18a and 18b gradually open as they descend. When 22a is completely fitted into the spindle part 21 and the magnetic pole piece lO is slightly bent, the pole piece lO becomes 45.
When the angle between the magneto-optical disk 1 and the tip of the pole piece IO is completely opened, the necessary gap between the surface of the magneto-optical disk 1 and the tip of the pole piece IO is set, and the strength of the magnetic field necessary for recording is set on the recording surface la. (Figure 5(c)). Next, in the ejection operation, the disk cassette 22 first rises, but at this time, the magnetic pole piece IO and the guide plates 18a, 18b are tilted at 45°~
Since it is installed at an angle of 60", it can be easily folded by pushing it in the east direction. After that, the disk cassette 22 is inserted into the magnetic pole piece 1 in the same way as when it was inserted.
0, push the guide plates 18a and +8b away and reach the insertion port in the reverse motion.

In this way, in this embodiment, the disk cassette 22 advances while pushing aside the magnetic pole piece 10 and the guide plates 18a and 18b, and when the magneto-optical disk 1 is set at the normal position where recording/reading is possible, the magnetic pole piece IO is also set, and conversely, when ejecting, the magnetic pole piece 10 and guide plate 18
It advances by pushing aside a and +8b, and sets 1f174 piece IO only when necessary.

(Effects of the Invention) As explained in detail above, according to the present invention, a coil wound in a flat F-shape around a magnetic pole piece is provided on a magnetic plate. , it can be made small and thin. Furthermore, since the structure is such that the magnetic pole piece is folded against the magnetic plate via the guide plate, the magnetic pole piece can be easily set only when needed, and the device can be made inexpensive.

Historically, when this device was applied to a magneto-optical disk device, the cassette moved by pushing away the guide plate when inserting and ejecting the disk cassette, allowing the folding of the pole piece to be carried out without requiring any other power. This makes it possible to provide magneto-optical disk devices at low cost.

[Brief Description of the Drawings] Figures 1 (a), (b), and (c) are block diagrams of an embodiment of the present invention, and Figures 2 (a) and (b) illustrate the principle of this embodiment. Basic configuration diagram, Figure 3 is an operation explanatory diagram of Figure 2,
Figure 4 is a diagram of the relationship between magnetic field components and distance, Figure 5 (a),
(b) and (c) are explanatory diagrams of adaptation examples of the external magnetic field generator, FIG. 6 is a diagram of a first conventional configuration example, and FIG. 7 is a diagram of a second conventional configuration example. ! ...Magnetic disk, 9...Magnetic plate, 10...Magnetic pole piece, II...Coil,! 2a, 12b -
--Magnetic flux, I 4--Magnetic field component, 15--Shaft, 16a, 16b = Bracket, 17--
Spring, +8a, 18b...Guide plate, 20...Magneto-optical disk, 21-...Spindle portion, 22...
Disk cassette, 22a-adsorption disk, 23...insertion [1, +00-...external magnetic field generator.

Claims (1)

[Scope of Claims] (a) a magnetic plate; (b) a magnetic pole piece that is 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 that extends radially around the magnetic pole piece. (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 is provided at the end of the magnetic pole piece and rotates the 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 the surface of the magnetic plate. An external magnetic field generator comprising: .