JPH0232692B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention relates to a magneto-optical recording device, and more particularly to a magneto-optical recording device that records, reproduces and erases information by condensing and irradiating a light beam onto a recording medium made of a magnetic thin film. .

Conventional technology In general, in this type of magneto-optical recording device, when recording information, a light beam is focused into a spot on a disc-shaped recording medium made of a thin film of uniaxially anisotropic magnetic material such as GdTbFe. By irradiating and heating the irradiated portion to a temperature near the Kyuri point, a magnetization reversal region is formed, thereby recording an information signal. Further, at this time, the light beam is irradiated onto the recording medium that is uniformly magnetized in the perpendicular direction while applying a magnetic field using an electromagnet or the like in a direction that facilitates magnetization reversal. On the other hand, when reproducing recorded information, a relatively weak light beam suitable for reading information is focused and irradiated onto the recording medium, and the Kerr rotation angle of the reflected light or transmitted light of the light beam is Alternatively, the reproduced signal is obtained by utilizing the fact that the Faraday rotation angle differs depending on the magnetization direction.

For this reason, in conventional devices, in order to constantly focus the light beam on the recording medium when recording and reproducing information,
An optical pickup is equipped with a drive mechanism that drives the entire optical system or a part of the optical system such as an objective lens in the focus direction (optical axis direction) using electromagnetic force. It has a magnetic field applying device such as an electromagnet that applies a magnetic field.

FIGS. 1 and 2 show examples of the configuration of such a conventional optical pickup and magnetic field applying device, respectively. First, to explain the conventional example shown in FIG. 1, the optical pickup 1 shown in the figure includes an objective lens 2 for condensing light, a lens barrel 3 that supports the objective lens 2, and an upper and lower part that supports the lens barrel 3 movably in the vertical direction. A pair of elastic supports 4a and 4b, a housing 5 that fixes the outer edges of the elastic supports 4a and 4b, a drive coil 6 for driving the lens barrel fixed to the lens barrel 3, and a pair of yokes that apply a magnetic field to the drive coil 6. 7a and 7b, a magnetic circuit consisting of their yokes and permanent magnets 8, and a galvanometer mirror 9 that horizontally displaces the light beam, and faces parallel to the recording surface of the recording medium 11 to which the light beam 10 is irradiated. It will be arranged as follows. On the other hand, the electromagnet 12, which is a magnetic field applying device that applies a magnetic field to the surface of the recording medium 11 when recording information, has a U-shaped ferromagnetic member 13 and a coil 14 that sandwich both sides of the recording medium 11. , is fixed to the casing 5 of the optical pickup 1 and moves integrally.

This optical pickup 1 records information in a track shape on the recording medium 11 with a light beam 10 while moving relatively parallel to the recording medium 11, and when reproducing information, the information track ( (not shown), information is reproduced using reflected light. At this time, the relative distance between the recording medium 11 and the optical pickup 1 changes due to unevenness on the surface of the recording medium 11, vertical movement during movement, external vibrations, and the like. Therefore, so that the light beam 10 is always focused on the recording medium 11, a photodetector (not shown) detects an error signal of the defocus, and depending on the detected value, the objective lens 2 is moved to the lens barrel 3 and the elastic support. A so-called focus control is performed in which a drive device including a drive coil 6 and magnetic circuits 7a, 7b, and 8 displaces the lens in the focus direction via bodies 4a and 4b. Furthermore, at the same time, in order to prevent the light beam 10 from deviating from the information track once grasped, a separately provided photodetector (not shown) detects the amount of track deviation, and the galvanometer mirror 9 is rotationally driven in accordance with the detected value. Thus, so-called tracking control for displacing the light beam 10 on the surface of the recording medium 11 is performed.

In the conventional example shown in FIG. 2, the optical pickup 1 is similar to that shown in FIG. The difference is that it is composed of an annular coil 14a arranged and a rod-shaped ferromagnetic pole 13a arranged facing the opposite side of the optical pickup with the recording medium 11 sandwiched therebetween.
When recording information, a current is passed through the coil 14a to generate a magnetic field, and the magnetic pole 13a on the reflective side of the recording medium 11 is magnetized, thereby strengthening the magnetic field applied to the recording medium 11.

However, in order to obtain the necessary magnetic field with the conventional magnetic field applying device 12 or 12a as shown in FIG. 1 or 2, the number of turns (turns) of the coil 14 or 14a must be increased, or It was necessary to increase the current applied to 14a. Therefore, the coil 14 or 14a
There were problems in that the volume of the optical pickup 1 increased, making it difficult to arrange the optical pickup 1 in terms of space, and increasing the weight of the optical pickup 1. Furthermore, there has also been the problem that the heat generated by the above-mentioned applied current has an adverse effect on the recording medium and the like.

Purpose In view of the above-mentioned points, the present invention reduces the weight and volume of the entire optical head including the optical pickup by using the leakage magnetic flux of the magnetic circuit as an auxiliary magnetic field during recording or erasing, and reduces heat generation etc. It is an object of the present invention to provide a magneto-optical recording device that has no adverse effects.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 shows an example of the configuration of the apparatus of the present invention, in which parts similar to those of the conventional apparatus shown in FIG. 1 are given the same reference numerals and detailed explanation thereof will be omitted. The optical pickup 31 shown in FIG. 3 is particularly different from the conventional device 1 shown in FIG. A protrusion 32 made of a ferromagnetic material is fixedly provided, and the protrusion 32 is disposed facing the recording surface of the recording medium 11.

As a result, the leakage magnetic flux leaking from the above-mentioned magnetic circuit is guided to the vicinity of the recording medium 11 via the above-mentioned protrusion 32 as shown by the arrow 33 in the figure, and the magnetic field is strengthened on the recording medium. Therefore, when recording and reproducing information, a magnetic field in a direction that tends to cause magnetization reversal acts on the recording medium due to the leakage magnetic flux of the magnetic circuit applied via the protrusion 32, so that the light beam is Information can be recorded by irradiation. Note that even when reproducing information using the same optical pickup, since the reading light beam is weaker than the writing light beam, the information can be reproduced without magnetization rotation regardless of the effect of the above-mentioned magnetic field.

In this way, according to this embodiment, the objective lens 2
Since the magnetic field can be applied to the recording medium using the leakage magnetic flux of the magnetic circuit that drives the optical head, there is no need for a conventional magnetic application device consisting of an electromagnet or coil, and as a result, the entire optical head including the optical pickup The effects of significantly reducing weight and volume and eliminating adverse effects such as heat generation due to applied current can be obtained.

FIG. 4 shows another embodiment of the present invention, in which an optical pickup 41 shown in the figure has almost the same structure as the device 31 of the previous embodiment shown in FIG. The difference is that a magnetic flux concentration member 42 made of a rod-shaped ferromagnetic material is disposed at an opposing position. Therefore, in the present embodiment shown in FIG. 4, the leakage magnetic flux coming out of the protrusion 32 of the magnetic circuit is
Since the magnetic field is concentrated on the ferromagnetic member 42 through the magnetic field, the strength of the magnetic field applied to the recording medium 11 can be further increased. Note that the above-mentioned member 42 may be made movable depending on the magnetic field strength.

Next, another embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 5, the magnetic circuit of the optical pickup 51 is the same as that shown in FIG. There are 53 locations. As a result, the leakage magnetic flux leaked from the magnetic circuit magnetizes the ferromagnetic member 52,
Furthermore, a magnetic field can be applied to the recording medium 11 by the ferromagnetic member 52.

Although the above-mentioned embodiments have been explained using recording as an example, the present invention can also be applied to an optical pickup in which information is erased by focusing a light beam on at least a recording medium, and in that case as well. , it is possible to apply an auxiliary magnetic field in the direction of erasing information on a recording medium with a simple configuration.

Effects As explained above, according to the present invention, the leakage magnetic flux emitted from the magnetic circuit of the optical pickup is guided onto the recording medium and used as an auxiliary magnetic field when recording or erasing information. The necessary magnetic field can be applied to the recording medium when recording or erasing information without the need for a separate magnetic field application means.As a result, the optical head can be made lighter and smaller, and it can also be used without any adverse effects such as heat generation. This has the effect that it can also be removed.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal sectional views showing an example of the configuration of a conventional device, FIG. 3 is a longitudinal sectional view showing an example of the configuration of the device of the present invention, and FIG. 4 is a longitudinal sectional view of another example of the configuration of the device of the present invention. FIG. 5 is a longitudinal sectional view showing another example of the configuration of the device of the present invention. 1, 31, 41, 51...light pickup, 2...
Objective lens, 3... Lens barrel, 4a, 4b... Elastic support, 5... Housing, 6... Drive coil, 7a, 7b... Yoke, 8... Permanent magnet, 9... Galvanometer mirror, 10
...Light beam, 11...Recording medium, 12...Electromagnet, 1
2a... Magnetic field applying device, 13, 13a... Ferromagnetic member, 14, 14a... Coil, 32... Ferromagnetic protrusion, 33... Leakage magnetic flux, 42, 52... Ferromagnetic member, 53... Support member.

Claims (1)

[Claims] 1. In a magneto-optical recording device that records or erases at least information by condensing and irradiating a light beam onto a recording medium made of a magnetic thin film using an optical pickup having an optical system, the optical system is moved in a predetermined direction. A magneto-optical recording device characterized in that leakage magnetic flux emitted from a magnetic circuit constituting an electromagnetic driving means for displacement is used as an auxiliary magnetic field during recording or erasing.