JPH01178105A - Magnetic field electromagnet for magneto-optical disk - Google Patents

Abstract

PURPOSE:To attain high speed switching with a large magnetic field by using a high permeability magnetic substance separated into two as a high permeability magnetic substance opposite to both sides of a magneto-optical disk and providing a device separating and connecting the upper half of the high permeability magnetic substance and a stationary lower half. CONSTITUTION:The high permeability magnetic substance formed as U-shape folded at the circumference part of the magneto-optical disk 11 is formed by 1st and 2nd high permeability magnetic substances 1, 2 having a separation border at the folded part, and the 1st and 2nd high permeability magnetic substances 1, 2 oppose respectively to the front and rear faces of the magneto-optical disk 11 respectively. A 1st coil 8 is provided on the magneto-optical disk face around a hollow 21 provided on the tip of the 1st high permeability magnetic substance 1, and coils 7, 9 generating a magnetic field in the same direction as that of the magnetic field generated in the 1st coil by a recording current from a magnetic field generating current modulation circuit 10 are provided on the 2nd high permeability magnetic substance 2. Moreover, a magnet separation device 3 to disconnect and couple the 1st high permeability magnetic substance 1 from the 2nd high permeability magnetic substance 2 to be fixed is provided. Thus, high speed switching with a large magnetic field is attained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic field applying electromagnet for a magneto-optical disk.

[Conventional technology]

When erasing recorded information in conventional magneto-optical recording, an external magnetic field is applied with the opposite polarity to that during recording, and a laser beam is uniformly irradiated onto the recording medium with the same intensity as during recording.
So-called -batch deletion is performed. That is, by applying an external magnetic field, the magnetization state of the recording medium is returned to the initial state before recording.

Here, known external magnetic field applying means include, for example, a method using an air-core coil, a method using an electromagnet, or a method using a permanent magnet.

[Problem that the invention seeks to solve]

In the above-mentioned magnetic field applying means, an applied magnetic field of several hundred or more steps is usually required during recording and erasing, so when an air-core coil is used, the coil becomes large, and along with this, the magnetic field switching becomes difficult. This method has the disadvantage that the speed is slow and that the required applied magnetic field cannot be obtained unless the distance between the recording medium and the coil is sufficiently close. Furthermore, when electromagnetic sound is used, the magnetic field applying means is large in size and the inductance of the coil is large, resulting in a slow magnetic field switching speed. Furthermore, when permanent magnets are used, a complicated bottle mechanism is required to switch the magnetic field using mechanical drive means, and the switching speed of the magnetic field is also slow in this case. As mentioned above, the magnetic field switching speed is slow with any conventional external magnetic field applying means, so the aforementioned batch erasing method is used for erasing, and when recording, the laser beam is turned off while a constant magnetic field is applied. A method of high-speed modulation is used. That is, the conventional apparatus has a problem in that it is difficult to provide a so-called override function for rapidly overwriting new information on already recorded information.

The purpose of the present invention is to solve such conventional problems,
It is an object of the present invention to provide a magnetic field applying electromagnet for a magneto-optical disk, which has a novel external magnetic field applying means that enables high-speed switching of a large magnetic field, and further facilitates the attachment and detachment of an optical disk.

[Means for Solving the Problems] The magnetic field applying electromagnet for a magneto-optical disk of the present invention is folded around the periphery of the magneto-optical disk to form a U-shape, has a separation boundary at this folded portion, and has a separation boundary between the two sides of the U-shape. A high magnetic permeability magnetic material having two linear portions facing each of both sides of the magneto-optical disk, and a first magnetic material provided on the surface side of the magneto-optical disk around a hollow portion provided at one end of one of the linear portions. coil and
A plurality of coils provided in at least one of the straight portions to generate a magnetic field in the same direction as the first coil and the U-shaped high permeability magnetic body are separated at the separation boundary.
and a connecting mechanism for coupling.

Here, the high permeability magnetic material is ferrite) (MnZn.

NiZn, etc.), Permalloy (NiFe), Sendust, 7-F-A/7 a, x, (CoZr, FeCoZ
r, CoNb.

(CoTa, CoHf, etc.), iron core, etc.

In addition, a U-shaped high magnetic permeability magnetic body with a concentric hollow is set between the laser condensing lens and the magneto-optical medium, and the inner diameter of the hollow allows the laser beam to pass through, and the tracker moves the lens in the track direction. The size is set so that it can be moved.

Further, the upper half of the U-shaped high permeability magnetic body can be separated by another electromagnet, so that the magneto-optical disk can be easily attached and detached. Therefore, when the magneto-optical disk is set, the two straight parts of the U-shaped high permeability magnetic material are magnetically coupled, and when the magneto-optical disk is removed, the U-shaped high permeability magnetic material is magnetically coupled. The two straight sections are magnetically separated. By doing so, the magneto-optical disk can be easily attached and detached, and a magnetic field sufficient for writing can be generated at high speed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. In this embodiment, a high permeability magnetic material is folded in a U-shape at the periphery of the magneto-optical disk 11, and a first high permeability magnetic material 1 and a second high permeability magnetic material 1, each having a separating boundary surface at the folded portion, are formed into a U-shaped high permeability magnetic material. Magnetic property magnetic material 2
first and second high permeability magnetic bodies 1
and 2 face the front and back surfaces of the magneto-optical disk 11, respectively. Further, a first coil 8 is provided on the magneto-optical disk surface side of the hollow portion 21 provided at the tip of the first high permeability magnetic body 1, and a magnetic field is applied to the second high permeability magnetic body 2. Coils 7 and 9 are provided in which a magnetic field is generated in the same direction as the magnetic field generated in the first coil 8 by the recording current from the generated current modulation circuit 10. Furthermore, a magnet separation mechanism 3 for separating and combining the first high magnetic permeability magnetic body l from the fixed second high magnetic permeability magnetic body 2
The structure is set up.

In the above configuration, by flowing current from the magnetic field generation current modulation circuit 10 to the coils 7.8 and 9, a perpendicular magnetic field is applied to the recording medium, which is the magnetic thin film 12 provided on the back side of the magneto-optical disk 11. It will be done. Note that the total length of the first and second high permeability magnetic bodies 11 is about 20 cm, and the wire diameter of the coils 7.8 and 9 is 150 cm.
about μm, and the current value is 10 mA to 1. OA is appropriate.

With the magnetic field applying means configured in this manner, it is easy to reduce the inductance L of the coil, so that it is easy to reduce the inductance L of the coil, so that the inductance L of the coil can be easily reduced by
It is possible to easily change the magnetic field of 00 oerste or de at a high speed of several MHz.

FIG. 2 is a block diagram of a magneto-optical recording and reproducing apparatus in which a peripheral system is added to the embodiment shown in FIG.

In FIG. 2, the output current of the magnetic field generation current modulation circuit 10 flows through coils 7.8 and 9, and upward and downward magnetic fields are alternately applied to the recording medium composed of the magnetic thin film 12 of the magneto-optical disk 11.

The card 31 for magneto-optical recording is the same as the conventional one and has the following configuration. 32 is a linearly polarized laser light source, for example, a semiconductor laser is used. 33, 34.
35 is a beam splitter. The laser beam focusing lens 36 is supported by an actuator 37. The focus error signal and the tracking error signal are detected by the focus error signal detection light receiving element 38. The signal is input to the servo control circuit 40, 41 by the light receiving element 39 for detecting the error signal, and is fed to the actuator 37 as a servo signal. After the reproduced signal passes through the polarizing filter 42t, it passes through the reproduced signal light receiving element 43.
and is amplified by the reproduction signal amplification circuit 44. A Gram-Tommon prism is used as the polarizing filter 42, and a PI is used as the light receiving element 43 for detecting the reproduced signal.
An N photodiode was used. A laser light source modulation circuit 45 is used to modulate the laser light source 32, and the power of the laser light is modulated during recording, erasing, and reproduction.

As a magneto-optical disk, T was further deposited on SiN formed on a plastic substrate with a diameter of 120 mm by a sputtering method.
b F e Co film with a thickness of 800 angstroms,
5iNt? is further formed on this TbFeCo film. The formed disc was used. The substrate used was a so-called pre-group substrate in which grooves with a track pitch of 1.6 μm and a depth of 700 angstroms were formed in advance.

3(a) to 3(C) are recording operation mode diagrams. Recording is performed by passing a modulated current as shown in FIG. 3(b) through the coils 7.8 and 9 for applying an external magnetic field while irradiating a laser beam with a constant intensity that can raise the temperature above the Curie temperature of the recording medium. An external magnetic field corresponding to the pattern is applied, and a recording magnetization state as shown in FIG. 3(C) is realized in accordance with the direction of the applied magnetic field during the cooling process accompanying the running of the recording medium.

First, while irradiating a laser beam with a constant intensity of 4 mW onto the disk surface at a linear velocity of 9 m/sec, a modulated current of 800 mA at IMHz was applied to coils 7.8 and 9 of the external magnetic field applying means. So it's 4. On this recording track, a new recording magnetic field 'k 0.5 M is applied under the same conditions.
When applied at Hz, recording corresponding to this recording magnetic field was possible, and no trace of previously recorded signals remained.

〔Effect of the invention〕

As described above, according to the present invention, a high permeability magnetic material that can be separated into two is used as the high permeability magnetic material facing both sides of the magneto-optical disk, and the upper half of the high permeability magnetic material is separated into two parts. Because it has a mechanism that can separate and connect the fixed lower half, it is easy to attach and detach the optical disk.Furthermore, since the inductance of the coil can be reduced, high-speed switching of a large magnetic field is possible, and it is possible to utilize magnetic flux. It is possible to provide an efficient magnetic field applying electromagnet for a magneto-optical disk.

Therefore, the magneto-optical recording and reproducing method has the advantage that it is possible to achieve override performance that allows desired recording to be performed directly without the need for conventional batch erasing, and that the disk can be easily attached and detached.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of the embodiment of FIG. 1 applied to a magneto-optical disk device,
FIG. 3 is an operational mode diagram of the recording shown in FIG. 2. 1.2... High permeability magnetic material, 3... Magnet separation mechanism, 7, 8, 9... Coil, 10...
...Magnetic field generation current modulation generation circuit, 21...
Hollow part, 31...For magneto-optical recording, C, 11.
...Optical disk substrate, 12...Magnetic thin film, 32...Laser light source, 33, 34°15...
・・・Beam splitter, 36...Laser light beam condensing lens, 37...Actuator,
38... Light receiving element for focus error signal detection, 39... Light receiving element for king error signal detection, 40° 41... Servo control circuit, 42...
... Polarizing filter, 43 ... Light receiving element for detecting reproduced signal, 44 ... Amplification circuit, 45 ...
...Laser light source modulation circuit. Agent Patent Attorney Otome Uchihara 3 Figure

Claims (1)

[Claims] a high magnetic permeability magnetic material that is folded back at the periphery of the magneto-optical disk to form a U-shape, has a separation boundary at the folded portion, and two straight portions of the U-shape face each of both surfaces of the magneto-optical disk; A first coil provided on the surface side of the magneto-optical disk around a hollow portion provided at one end of one of the linear portions generates a magnetic field in the same direction as the first coil in at least one of the linear portions. 1. A magnetic field applying electromagnet for a magneto-optical disk, comprising: a plurality of coils arranged to do so; and a connection mechanism that separates and connects the U-shaped high permeability magnetic body at the separation boundary.