JPH01150261A - Magneto-optical recording device - Google Patents

Abstract

PURPOSE:To miniaturize a driving device and to obtain a device interchangeable with a half height type magnetic recording device by fixedly arranging a permanent magnet in a magnetic field generating system and moving an optical beam projecting position in accordance with recording, reproducing and erasing. CONSTITUTION:Magnetic poles 21, 22 arranged in parallel are fixed on the upper side of a magneto-optical disk 3. An optical head 25 provided with an objective lens moving mechanism 28 is arranged on the lower side of the disk 3. At the time of recording information, a driving coil 36 is excited and the magnetic pole 34 of the permanent magnet 33 coupled with a supporting frame 31 for the objective lens 32 is attracted. Consequently, the optical axis 39 of the lens 32 forms an optical spot 42 on a position opposed to the magnetic pole 21 and the information is recorded in a magnetic field downward from the disk 3. At the time of erasing information, a coil 37 is excited, a magnetic pole 35 is attracted and an upward magnetic field is impressed. At the time of reproduction, both the magnetic poles 34, 35 are repulsed. Thereby, the weight of a movable part can be reduced and the interchangeability with the half height type magnetic recording device can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention magnetically records, erases, and reproduces information on a magneto-optical recording medium such as a magneto-optical disk through projection of a light beam. Magneto-optical recording devices, especially their recording,
Concerning the mechanism of erasure and reproduction.

[Conventional technology]

In magneto-optical recording media, recording is performed by magnetizing the medium in a direction perpendicular to the surface of the medium, and this direction is opposite to the direction of magnetization in the erased state. Therefore, in the case of recording or erasing, an external magnetic field is applied perpendicularly to the medium surface in a direction corresponding to each state of recording or erasing, and a diameter of 1 μm is applied to the information track as an information recording groove.
A focused light beam is irradiated onto a minute spot in the vicinity of m to raise the temperature of the information recording section on the information track to near the K and L temperatures, and magnetize the medium in the direction of the applied magnetic field. Furthermore, when reproducing information, no magnetic field is applied, and a linearly polarized light beam of low intensity is projected onto the medium. When this light beam is reflected by the surface of the magnetized medium, the direction of its polarization is rotated by the Kerr effect in accordance with the direction of magnetization relative to the direction of polarization of the incident light. This reflected light is detected through a detector to obtain a light intensity signal corresponding to the rotation direction of polarization, that is, the recording state of information.

FIG. 3 shows an example of a magnetic field generation system that uses an electromagnet to apply an external magnetic field when recording or erasing as described above. An electromagnet 2 as a magnetic field generating system 1 has a magnetic pole 6 arranged with an excitation winding 5 in a direction intersecting an information track 4 of a magneto-optical disk 3 as a magneto-optical recording medium. Depending on the state of recording or erasing information, the direction of the excitation current applied to the excitation winding 5 is changed to provide a corresponding magnetic field. A light beam (not shown) is projected from below the magneto-optical disk 3 and forms a light spot on its lower surface.

FIG. 4 shows another conventional example in which a permanent magnet 8 is used in the magnetic field generating system 7.

Magnetic poles 9 and 10 are provided at both poles of the permanent magnet 8, and these magnetic poles are moved along the information track 4 in the direction of the arrow by the drive device 11, so that the light beam 13 projected from the optical radar 12 is focused. The direction of the magnetic field at the position of the minute light spot 14 created by this is changed. Dotted lines indicate lines of magnetic force 15.

(a) shows the recording state, (b) shows the playback state, and (C) shows the erasing state.

[Problem that the invention seeks to solve]

Magneto-optical recording devices have an information recording density about an order of magnitude higher than magnetic recording devices using magnetic disks, which are currently widely used, and it is desired that they be compatible with these magnetic recording devices. In particular, providing compatibility with personal computers, where magnetic recording devices are most commonly used, would greatly increase the storage capacity of current devices, and this would be a great advantage.

The external dimensions of the magnetic recording device in this personal computer are approximately 40 mm in height, approximately 150 nm in width, and approximately 2 in depth.
00mm half-hide type.

By the way, recording and erasing information in a magneto-optical recording device requires a strong magnetic field of 400 to 6000 e.
In order to provide this magnetic field with a normal electromagnet, a large excitation current is applied to an excitation winding with a large number of turns. In order to achieve this without causing problems such as heat generation, the electromagnets in current magneto-optical recording devices are large, and the device is approximately 8.8 cm in height.
It is constructed of 0mm full hide type. Therefore, in order to construct a half-hide type using an electromagnet, it is necessary to apply a large current to the thin excitation winding in addition to applying the above magnetic field, making the operating conditions harsh and requiring heat removal measures. .

The magnetic field generating system 7 shown in FIG. 4 uses a permanent magnet 8 in order to avoid the above-mentioned problems, but in order to provide the above-mentioned strong magnetic field, it is possible to reduce the weight of the permanent magnet provided with the magnetic poles 9 and 10. There is a limit to this, and there is a problem in fitting the drive device 11 that drives this into a limited space. Also, the transit time of one sector as a unit area in which a series of information is recorded is approximately 1
+ms, and it is not easy to drive the relatively heavy magnetic field generation system 7 to accurately stop it at a predetermined position in a very short time in response to a group of information moving at such high speed.

It is an object of the present invention to solve the above-mentioned problems and provide a compact magneto-optical recording device that is compatible with the current half-hide magnetic recording device.

[Means for solving problems]

In this invention, a magnetic field generating system is fixedly disposed on one side of a magneto-optical recording medium in a direction intersecting an information recording groove, and the magnetic field generating system is arranged at least in the width of an area on the magneto-optical recording medium where the information recording groove is provided. It consists of a permanent magnet with parallel magnetic poles of different polarities and corresponding lengths, and an optical head that projects a light beam on the opposite side of the magneto-optical recording medium from the magnetic field generation system. The optical head is equipped with a light beam irradiation position moving means to move the light beam projection position along the information recording groove to positions opposite to one and the other of the magnetic poles, respectively, and to a position intermediate therebetween. It is.

[Effect]

By moving the projection position of the light beam and fixedly arranging the magnetic field generation system made up of permanent magnets, there is no need for electromagnet windings or permanent magnet drive devices, which are problems when downsizing the device. . In addition, since the movement of the light beam is performed by moving small, lightweight optical parts, it can sufficiently follow the movement of recorded information at high speeds.Furthermore, the drive device can be configured to be extremely compact, so there is no need to increase the size of the optical head. .

〔Example〕

FIG. 1 schematically shows an embodiment of the invention. In the magneto-optical disk 3 as a magneto-optical recording medium, the direction of the information track is parallel to the plane of the paper. On the upper side of the magneto-optical disk 3, a permanent magnet 23 having magnetic poles 21 and 22 arranged in parallel in a direction intersecting the information track is fixedly arranged as a magnetic field generating system 24.

An optical head 25 is arranged below the magneto-optical disk 3, and an objective lens support 2 provided on the optical head 25
An objective lens moving mechanism as a light beam projection position moving means is installed above the light beam projection hole 27 of No. 6.

In the objective lens moving mechanism, there is a support frame 31 that fits into a guide 30 provided on the bottom plate 29 and is movable along the information track, and the objective lens 32 is supported by this support frame 31. On both sides of the support frame 31 in the moving direction, magnetic pole pieces 34 and 35 of different polarity are connected to the permanent magnet piece 33 shown in dotted lines. Bottom plate 2
Hollow drive coils 36 and 37 are fixed to both ends of the coil 9, and the hollow portions are spaces into which magnetic pole pieces 34 and 35 can fit, respectively.

38 is a stopper for the support frame 31.

FIG. 1(a) shows the state during information recording, in which only the drive coil 36 is energized to attract the magnetic pole piece 34, and the objective lens 32 is moved to the left together with the support frame 31. In this state, the optical axis 39 of the objective lens 32 is located to the left of the optical axis 41 of the projected light beam 40, and therefore the light beam 40 projected as parallel light is directed to the objective lens 32 located to the left. The light is focused onto the magneto-optical disk 3 on the optical axis 39 to form a light spot 42 at a position facing the magnetic pole 21 . Magnetic field lines 43 due to magnetic field generation system 24
is formed as shown by the dotted line in the figure, so the magnetic field at the position of the optical spot 42 is perpendicularly downward with respect to the magneto-optical disk 3, so that the magnetic recording layer of the magneto-optical disk 3 is magnetized downward and information is stored. Record.

3) shows the state when information is erased, in which only the drive coil 37 is energized to attract the magnetic pole piece 35, and the support frame 31
At the same time, the objective lens 32 is moved to the right. As a result, the optical axis 39 of the objective lens 32 is positioned to the right of the optical axis 41 of the light beam 40, and a light spot 42 is formed at a position facing the magnetic pole 22, in the opposite direction to that during recording, that is, in the same direction as the initial magnetization direction. The information is erased by magnetizing it.

(C) shows the state during information reproduction. In this case, when recording both the drive coils 36 and 37,
The magnetic pole pieces 34 and 35 are both repelled by the drive coils 36 and 37 by being excited by a current in the opposite direction to that during erasing, so that the support frame 31 is centered, and the optical axis 39 of the objective lens 32 is aligned with the light beam 40. almost coincident with the axis 41.

When the support frame 31 moves in either direction from this center position, the respective repulsive forces become unbalanced, and a force acts to return the support frame 31 to the center position, so the support frame 31 stably stops at the center position. are doing. In this case, the optical spot 42 is formed approximately at the center of the magnetic poles 21 and 22. At this position, the magnetic field generated by the magnetic field generation system is formed in the horizontal direction and has no vertical component. Therefore, the perpendicular magnetization corresponding to the information recorded on the magneto-optical disk 3 is optically read via the Kerr effect to reproduce the information.

Since the support frame 31 and the objective lens 32 are extremely lightweight, they can be moved with little force, and therefore the permanent magnet piece 33. Pole piece 34.35', drive coil 3
6.37 can be made extremely compact.

This makes it possible to move the light spot 42 within a very short time and switch between recording, erasing, and reproducing states.

FIG. 2 also schematically shows another embodiment of the invention.

In this embodiment, a rotatable reflecting mirror 52 provided within an objective lens support 51 of an optical head 50 is used as a light beam projection position moving means.

This reflecting mirror 52 is attached to a rotating shaft 56 of a moving coil 55 arranged between magnetic poles 53, 54 of a permanent magnet. The moving coil 55 is given a structure similar to that of a moving coil type instrument. The spring 57 is used to keep the reflecting mirror 52 stationary at a predetermined rotational angle by a restoring force that balances the rotational force generated when a current is applied to the movable coil 55.

FIG. 2(a) shows the state during information reproduction,
No current is applied to the moving coil 55.

In this state, the reflecting mirror 52 is supported by the undeformed spring 57 and remains stationary. In this state, the light beam 58 projected in the horizontal direction is reflected by the reflecting mirror 52, and its leading axis 59 almost coincides with the optical axis 61 of the objective lens 60, and is centered between the magnetic poles 21 and 22 on the magneto-optical disk 3. is projected to the position of , forming a light spot 62 .

(b) and (C) respectively show the recording and erasing states, in which the direction of rotation of the reflecting mirror 52 is changed by changing the direction of the current applied to the movable coil, respectively.
Along with this, the inclination angle of the reflective surface 63 is changed to move the light spot 62 to the respective recording and erasing positions. In this case, the current value is controlled to a value that provides the required rotation angle.

The reflecting mirror 52 and the movable coil 55 are made extremely small and lightweight, and can move the light spot 62 in a very short time with a small amount of current.

〔Effect of the invention〕

According to this invention, the magnetic field generation system is a fixed permanent magnet, and the projection position of the light beam is changed by means for moving the projection position of the light beam, which is composed of extremely lightweight and small parts. Therefore, the configuration of the magnetic field generation system is simplified, there is no need to use electromagnets or permanent magnet drive devices that occupy a large space, and the polarity of the magnetic field at the light beam projection position can be switched within an extremely short time. can. Therefore, the entire magneto-optical recording device can be made compact without deteriorating its performance, and it is possible to provide compatibility with half-hide magnetic recording devices.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration and operation of an embodiment of the present invention;
FIG. 2 is a schematic diagram showing the configuration and operation of another embodiment of the present invention, FIG. 3 is a perspective view of a conventional magnetic field generation system using electromagnets, and FIG. 4 is a diagram of a conventional magnetic field generation system using permanent magnets. FIG. 2 is a schematic diagram showing the configuration and operation of a magnetic field generation system. Top, Y, B Magnetic field generation system, 3 Magneto-optical disk (magneto-optical recording medium), 4 Information track (information recording groove), 8, 2
3- Permanent magnet, 9.10.21.22 Magnetic pole, 12
．． 25.50・Optical head, 13.40.58 Light beam, 14.42.62・Light spot, 1 Objective lens moving mechanism (light beam projection position moving means), 32 Objective lens, 52 Reflector (light beam projection position moving means)
, 63 - reflective surface. Figure 3 Figure 4

Claims (1)

[Claims] 1) An optical head that projects a light beam onto an information recording groove on a magneto-optical recording medium, and a magnetic field generation system that applies an external magnetic field of different polarity to the projection position of the light beam; In a device that records, reproduces, and erases information according to the polarity of an external magnetic field, a magnetic field generation system is fixedly arranged on one side of a magneto-optical recording medium in a direction intersecting an information recording groove, and at least magneto-optical recording Consisting of a permanent magnet with parallel magnetic poles of different polarity and a length corresponding to the width of the area where the information recording groove is provided on the medium, and placed on the side opposite to the magnetic field generation system with respect to the magneto-optical recording medium. The optical head is characterized in that the optical head is provided with a light beam projection position moving means for moving the light beam projection position along the information recording groove to positions respectively facing one and the other of the magnetic poles and to a position intermediate therebetween. magneto-optical recording device. 2) In the device according to claim 1, the light beam projection position moving means includes a lens for converging the light beam and projecting it to the light beam projection position, and a lens for moving the lens in a direction perpendicular to the optical path of the light beam. What is claimed is: 1. A magneto-optical recording device comprising a drive mechanism for moving the device. 3) A magneto-optical recording apparatus according to claim 1, wherein the light beam projection position moving means is a reflecting mirror driven to change the inclination of the reflecting surface.