JPH02137150A - Magneto-optical recording device - Google Patents

Abstract

PURPOSE:To reduce power consumption by arraying and arranging plural magnetic cores in the moving direction of a light beam with which a recording medium is irradiated and supplying a current to the coil of the magnetic core arranged at a position corresponding to an irradiating position by the light beam so that magnetic field is impressed on a recording part. CONSTITUTION:The magnetic cores 7a-7e are arrayed and arranged in the moving direction of an optical head 3(that is, the radial direction of a magneto- optical disk 1) above a magneto-optical disk 1. When the optical head 3 is moved by a motor 4 and it reaches a recording position, the magneto-optical disk 1 is irradiated with the laser light. At such a time, the position of the optical head 3 is detected by a position sensor 6 and a control circuit 10 outputs a control signal to a current supply circuit 9, so that one or two coils which are the nearest to the irradiating position by the laser light are energized to generate the magnetic field on the position. Thus, the power consumption is reduced by locally forming the magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magneto-optical recording device that performs recording using the magneto-optic effect.

(Prior art) A magneto-optical recording device has a magnetic field generating device consisting of one or more magnetic cores and a coil wound around each magnetic core, and by exciting the coil, it generates light that is a recording medium. Data is recorded by applying a necessary magnetic field onto the magnetic disk and by irradiating the recording portion of the magneto-optical disk with laser light from a separately provided optical head to generate a magneto-optic effect. The optical head is moved in the radial direction of the disk using a moving means such as a DC motor or a stepping motor, and recording bits can be created at any position within a predetermined range on the disk (Japanese Patent Laid-Open No. 63-9001).
No. 63-56837).

By the way, in conventional devices, a single magnetic field generating device generates a magnetic field over the entire range of the recordable area on the disk. As a result, the coil and magnetic core have become larger, and since the current flowing through the coil has also become larger, the drive device for the magneto-optical disk has also become larger, and a larger power supply has therefore been required. In some cases, the heat generated by the coil may cause an increase in temperature or smoke.

In order to solve this problem, it is conceivable to mechanically connect the magnetic field generator and the optical head so that the magnetic field generator moves together with the optical head. However, this method has disadvantages in that the number of mechanically moving parts increases, which reduces the reliability of the device, and also increases the access time because the moving parts become larger.

(Object and Structure of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to provide a compact magnetic recording device with low power consumption.

To achieve this purpose, multiple magnetic cores are arranged side by side in the moving direction of the light beam irradiated onto the recording medium, and current is supplied to the coils of the magnetic cores placed at positions corresponding to the irradiation position of the light beam. It was configured so that a magnetic field was applied to the recording area.

(Example) The present invention will be explained below based on the drawings.

Figure #11 is a block diagram showing an embodiment of the magneto-optical recording device according to the present invention.

In the figure, 1 is a magneto-optical disk that rotates around a spindle 2, 3 is an optical head that irradiates the magneto-optical disk 1 with laser light, and 4 is a moving means for moving the optical head 3 in the radial direction of the magneto-optical disk l. 5 is a drive circuit for the motor 4, and 6 is a position sensor for detecting the moving position of the optical head 3.

Above the magneto-optical head l, five magnetic cores 7a to 7e are arranged side by side in the moving direction of the optical head 3 (ie, in the radial direction of the magneto-optical disk l). FIG. 2 is a plan view showing the arrangement thereof.

The magnetic cores should be arranged side by side in the direction of movement of the optical head.
Therefore, if the optical head is of the swing arm type as shown in FIG. 3(A), the magnetic cores 7 may be arranged in an arc as shown in FIG. 3(B). Further, these magnetic cores may be provided separately as shown in FIG. 1, but they may also be provided integrally in a single yoke.

Returning to FIG. 1, coils 88 to 8e are wound around each of the magnetic cores 7a to 7e, respectively. A predetermined current is supplied from a current supply circuit 9 to each coil. For example, 10 is CP
It is a control circuit composed of U, etc., and receives the output from the 1-position sensor 6 and selects the coil to which current should flow. 1
1 records (or erases or reads) to optical head 3
This is a signal processing circuit that sends and receives signals for.

Next, the operation of the embodiment will be explained by taking the case of recording data as an example.

First, the optical head 3 is moved by the motor 4, and when the optical head 3 reaches the recording position, the magneto-optical disk 1 is irradiated with laser light. At this time, the position of the optical head 3 is detected by the position sensor 6, and the control circuit 1O outputs a control signal to the current supply circuit 9 to energize one or two coils closest to the laser beam irradiation position. Generate a magnetic field at that location. FIG. 1 shows an example in which only the coil 8c is energized.

Depending on the device, the input data may include address information that indicates the recording position of the data, but in that case there is no need to provide a position sensor for the optical head, and the power is turned on based on the address information. Just select the appropriate coil.

As described above, according to the present invention, it is not necessary to generate a magnetic field over the entire recording range on the disk as in the conventional case, so the current flowing through the coil can be reduced, and the heat generation thereof can be suppressed.

Furthermore, since no mechanically moving parts are involved, the reliability of the device can be increased. Furthermore, since a large power source is not required and there are no mechanically moving parts, the device can be made smaller.

Incidentally, the magnetic flux density B at a point a distance x away from the coil on the central axis of the coil is generally expressed by the following equation.

(Left below) μo magnetic permeability N: Number of turns of coil ■: Current value
fL=Coil length a: Coil radius From this formula, the coil shape that can most efficiently obtain a strong magnetic field from the same value of current can be determined. For example, the number of turns N=200 is placed at a position lam away from the disk.
A coil of length Jl = 20 am is placed on the disk and 12
When it is desired to generate a magnetic flux of 0 gauss, it is most efficient to set the radius of the coil to a=approximately 611.

Now, in the case of a cylindrical coil, it is known that the distribution of magnetic flux density in the axial direction sharply decreases as the distance from the center of the coil approaches the radius of the coil. Therefore, if a current is simply passed through one of the arranged coils, and the light irradiation position by the optical head is between the coils,
There is a possibility that the required strength of magnetic flux may not be obtained.

Therefore, when the light irradiation position is between the coils, it is recommended to energize the two adjacent coils to apply a magnetic field.For example, if the optical head is now facing outward from the center of rotation of the disk 9. When moving with
As shown in (a), the coil 8a is first energized, and when the irradiation position of the optical head 3 comes between the coils 8a and 8b, both the coils 8a and 8b are energized. Similarly, as the optical door 3 moves outward, 8b→8b and 8c→8c→8
By energizing in the order of c and 8d-+8d+8d and 8e→8e, the necessary magnetic field can be obtained for all recording positions.

Furthermore, in order to eliminate the above-mentioned unevenness in magnetic flux density, the magnetic cores 7 may be arranged in a staggered manner as shown in FIG.

In the above embodiment, a disk-type recording medium was used as an example, but
It goes without saying that the present invention is not limited to this, but can also be applied to other types of magneto-optical recording devices, such as card-type recording media, which perform magneto-optical recording while moving a light beam. Furthermore, although the above example has been explained using a cylindrical coil and magnetic core as an example, the present invention is not limited to the shapes of the coil and magnetic core.

For example, the magnetic core may be shaped like an inverted letter as shown in FIG. FIG. 6(b) is a view of (a) viewed from six directions. By adopting the magnetic core shape shown in Figure 8, it is possible to reduce the unevenness of the magnetic field in the direction of movement of the laser beam, and furthermore, to concentrate the magnetic field in the direction perpendicular to the direction of movement of the laser beam, it is possible to reduce the unevenness of the magnetic field in the direction of movement of the laser beam. It is possible to reduce the wasteful magnetic field generated at the position.

It goes without saying that it is better to use a material with high magnetic permeability, such as a permalloy alloy, as the material for the magnetic core.

(Effects of the Invention) As explained above, according to the present invention, a plurality of magnetic cores are arranged side by side in the moving direction of the light beam irradiated onto the recording medium, and are arranged at positions corresponding to the irradiation position of the light beam. Since the magnetic field is locally formed by supplying current to the coil of the magnetic core and applying a magnetic field to the recording portion, it is possible to provide a compact magnetic recording device with low power consumption.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the magneto-optical recording device according to the present invention, Fig. 2 is a plan view showing the installation position of the magnetic core of the device of Fig. 1, and Fig. 3 is a different arrangement of the magnetic core. Figure 4 is a diagram showing an example of how to energize the coil, Figure 5 is a plan view showing another example of the installation position of the magnetic core, and Figure 6 is a diagram showing another example of the magnetic core shape. FIG. l...Magneto-optical disk, 3...Optical head, 7゜7
a~7e...magnetic core, 8a~8e...coil, 9 current supply circuit, 10-...control circuit

Claims (1)

[Claims] A magneto-optical recording device that performs magneto-optical recording while moving a light beam irradiated onto a recording medium includes a plurality of magnetic cores that are arranged in the direction of movement of the light beam and apply a magnetic field to the recording medium; a plurality of coils each wound around a core; a current supply means for supplying current to the coils; and a current supply means configured to supply current to a coil disposed at a position corresponding to the irradiation position of the light beam. What is claimed is: 1. A magneto-optical recording device comprising a control means for controlling the device.