JPS62128045A - Photomagnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To apply a vertical magnetic field efficiently by arranging a magnetic field applying device so that this device faces an optical head with a photomagnetic recording medium between them and providing an auxiliary magnetic pole piece consisting of a semihard magnetic material between the recording medium and an objective lens which forms a minute spot of laser light on the photomagnetic recording medium. CONSTITUTION:When a current (i) is flowed to an exciting coil 6, a magnetic flux phiis generated and is guided from a center yoke 5 to an auxiliary magnetic pole piece 9 arranged between a recording medium 1 and an objective lens 3 and flows in the direction of the axis of easy magnetization of the auxiliary magnetic pole and is guided to an outside yoke 7 and is guided to the center yoke 5 again to form a close magnetic circuit 4. At this time, the vertical magnetic field is applied to the recording medium 1 by the center yoke 5 and the auxiliary magnetic pole piece 9. Since the auxiliary magnetic pole piece 9 consists of a semihard magnetic material, it is magnetized by 100-500 gausses external magnetic field to act similarly to a magnet, and the magnetic flux phi is generated even after the current (i) flowing the exciting coil 5 is cut off. Consequently, it is sufficient if the current (i) is supplied to the exciting coil 6 only when the magnetic field is inverted by switching between erasing and recording modes.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magneto-optical recording and reproducing apparatus for writing, reading and rewriting information on a magneto-optical recording medium.

2. Description of the Related Art Optical disk memories have been widely researched and developed as memory devices with large storage capacities, high transfer rates, and high-speed access. In particular, since magneto-optical recording media are rewritable, their use as disk memory devices is considered important.

Information is written and rewritten on a magneto-optical recording medium using the so-called thermal core effect, which involves irradiating a laser beam that is narrowed down to a finely focused laser beam, heating the recording medium to a Curie temperature, and applying a perpendicular magnetic field to the recording medium. It is.

Conventionally, as a magnetic field applying device, an lenoid coil or the like has been arranged at a position facing an optical head. The conventional magnetic field application device mentioned above will be explained below with reference to the drawings.

FIG. 3 shows a conventional magneto-optical recording/reproducing device. In FIG. 3, a hunting circuit 4 is a magnetic field applying device that applies a perpendicular magnetic field for writing and rewriting information to a recording medium. A bar-shaped center yoke 5 arranged at opposing positions and having a distance corresponding to a distance sufficient to cover the access area of the optical head 2 along the access direction of the optical head 2, and an excitation coil wound around the center yoke 5. 6 and a U-shaped outer yoke 7 surrounding the center yoke 6.

The operation of the perpendicular magnetic field applying device of the magneto-optical recording and reproducing apparatus configured as described above will be described below.

By energizing the excitation coil 6, a magnetic flux φ flows through a magnetic path consisting of the center yoke 5 and the outer yoke 7. If the distance S between the center yoke 6 and the recording medium 1 is made sufficiently small, a perpendicular magnetic field can be applied to the recording medium 1 facing the tip of the center yoke 5. Furthermore, the provision of the external yoke 7 also improves the efficiency of the magnetic circuit.

Problems to be Solved by the Invention However, in the above configuration, the center yoke 6
When the distance between the recording medium 1 and the recording medium 1 is small, the condition is good, but surface runout,
When using a disk with large warp, etc., it is necessary to set the distance S between the magnetic circuit 4 and the recording medium 1 large, which causes the problem that it is difficult to obtain the required perpendicular magnetic field strength on the film surface of the recording medium 1. are doing. Furthermore, the perpendicularity of the magnetic field applied to the recording medium 1 is impaired, which adversely affects the recording and erasing characteristics, and the efficiency of generating the vertical field becomes poor, so that most of the applied magnetic field becomes a horizontal 8 field. In addition, when the efficiency of the vertical $ different component deteriorates, an excessive current is passed through the excitation coil 6 to apply a magnetic field, which generates heat in the magnetic field application device and requires a large-capacity power supply, which increases the size of the device and increases power consumption. It had the problem of becoming.

In view of the above-mentioned problems, the present invention provides a magneto-optical recording and reproducing apparatus that can efficiently apply a perpendicular magnetic field to a recording medium.

Means for Solving the Problems In order to achieve the above object, the magneto-optical recording and reproducing apparatus of the present invention includes a magnetic field applying device disposed at a position facing an optical head and sandwiching an optical recording medium, and an optical head. and a semi-hard magnetic auxiliary pole piece having an S-easy axis perpendicular to the S-easy axis of the optical lull recording medium, between the optical recording medium and the optical recording medium.

Effect With the above configuration, the magnetic flux from the magnetic field application device is guided to the auxiliary magnetic pole piece, and from the auxiliary piece to the outer yoke, increasing the perpendicular magnetic field on the recording medium film surface and maintaining perpendicularity even at a distance from the recording medium. Without this, a magneto-optical recording and reproducing device that can efficiently apply a magnetic field can be achieved. Furthermore, since it has an auxiliary magnetic pole piece made of semi-hard magnetic material, magnetic efficiency is good.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of an embodiment of the magneto-optical recording/reproducing apparatus of the present invention, and FIG. 2 is a perspective view showing the configuration of the main parts thereof. In FIG. 1, 1 is a recording medium, 3 is an objective lens, 4 is a magnetic circuit, and 6 is a center yoke, which are the same as those of the conventional example. Reference numeral 8 denotes an auxiliary magnetic pole piece, which is disposed between the objective lens 3 and the recording medium 1 and is a semi-hard magnetic material having S-air anisotropy perpendicular to the axis of easy magnetization of the recording medium 1. Further, the auxiliary pole piece 8 may be formed of a high permeability magnetic material, such as a silicon steel plate, anisotropic ferrite, single crystal ferrite, or the like. Furthermore, it may be formed of a hard magnetic material such as anisotropic strontium ferrite.

The operation of the magneto-optical recording and reproducing apparatus configured as described above will be explained below.

First, when a current i is passed through the exciting coil 6, a magnetic flux φ is generated. The magnetic flux φ is induced from the center yoke 6 to the auxiliary magnetic pole piece 9 placed between the recording medium 1 and the objective lens 3, flows in the direction of the axis of easy magnetization of the auxiliary magnetic pole, is guided to the outer yoke 7, and is guided back to the center yoke 6. A mother air circuit 4 is formed. At this time, a vertical magnetic field is applied to the recording medium 1 by the center yoke 6 and the auxiliary magnetic pole pieces 9.

Furthermore, the auxiliary magnetic pole piece 9 is made of semi-hard magnetic material.
It is magnetized by an external magnetic field of about 0.00 Gauss, performs the same action as an 8-stone magnet, and generates magnetic flux φ even after the current i flowing through the excitation coil 6 is cut off. Therefore, it is only necessary to supply electricity it to the assistance coil 6 when the S field is reversed by switching between erasing and recording modes.

In this example, the magnetic field application device is a so-called electric grinder made of excitation coils, but it is possible to similarly introduce a perpendicular magnetic field to the recording medium even with an 8-field application device using a permanent magnet. It is. Furthermore, it is also possible to apply a modulation current corresponding to the information signal to the 8 excitation coils, efficiently invert the N and S poles, and rewrite the information on the recording medium.

Effects of the Invention The present invention provides an abrasive field application device which is placed between a magneto-optical recording medium and facing an optical head, and forms a minute spot on the magneto-optical recording medium with a laser beam between the objective lens and the recording medium. By providing an auxiliary magnetic pole piece made of semi-hard magnetic material, the magnetic flux generated from the excitation coil can be efficiently guided as a closed magnetic path, and the formation between the center yoke and the auxiliary S pole piece can be made in the direction perpendicular to the recording medium. It is an effective component as a magnetic field for recording and erasing information, and it is possible to efficiently apply a magnetic field to a recording medium. Furthermore, it is only necessary to supply current to the excitation coil when the magnetic field is reversed, which makes it possible to reduce laser power, reduce heat generation due to a decrease in excitation current, and furthermore, as mentioned earlier, it is possible to achieve miniaturization of the recording and reproducing device.
It is possible to realize a magneto-optical recording and reproducing device that can obtain a number of excellent effects.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a magneto-optical recording and reproducing apparatus in an embodiment of the present invention, FIG. 2 is a perspective view showing the main parts of the present invention,
FIG. 3 is a sectional view of a conventional magneto-optical recording/reproducing device. 1...recording medium, 2...optical head,
3...Objective lens, 5...Center yoke, 6...Excitation coil, 7...Outer yoke, 9...Auxiliary S pole piece.

Claims (1)

[Claims] A recording medium including a magnetic thin film having perpendicular magnetization, an optical head that emits a minute spot of laser light onto the recording medium, and applying a magnetic field perpendicular to the film surface of the recording medium when writing or erasing information on the recording medium. and a magnetic field generating device,
A magneto-optical device having a configuration in which a disc-shaped auxiliary magnetic pole piece made of a semi-hard magnetic material having anisotropy in a direction perpendicular to the axis of easy magnetization of the magnetic field generator and the recording medium is arranged between the optical head and the recording medium. Recording and playback device.