JPH01220163A - System and device for magneto-optical recording - Google Patents

Abstract

PURPOSE:To enlarge the selecting range of the material of a magnetizing film and to use a magnetism generating source which is compact and has high performance by magnetizing the magnetizing film of a magneto-optical disk in an in-plane direction and executing the recording or erasing of information. CONSTITUTION:An optical disk 21 to use an in-plane magnetizing film is revolved around a shaft center and a magnetic field is impressed from a ring-shaped magnetic head 22 in the diameter direction of the optical disk 21. On the other hand, a laser beam to be outgoing from a semiconductor laser 23 is passed through a condenser lens 24, a prism 25 for shaping, a beam splitter (BS) 26 and an objective lens 27 and condensed to the magnetizing film. Thus, the temperature of the magnetizing film raises near a curie point or above a compensating temperature and the film is magnetized in the magnetic field impressing direction of the head 22. Then, the information are recorded or erased. At the time of reproducing, a reflected light whose polarizing surface is turned in correspondence to the magnetization is passed through the objective lens 27, the BSs 26, 28, a lambda/2 board 31 and a condenser lens 32 and separated into P and S components by a polarizing BS 34. Then, the light is incoming to photo-diodes 33 and 35 and an output is inputted to a differential amplifier 36. Then, the information is reproduced by a difference signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording system for recording and reproducing information using magneto-optical effects, and a device used therefor.

[Conventional technology]

As information becomes more sophisticated, information file devices are required to have larger capacities and higher densities, and magneto-optical disk devices are attracting attention as rewritable high-density recording devices.

FIG. 4 is a diagram showing the concept of a magneto-optical recording method in a conventional magneto-optical disk device.
Laser light 45 focused by objective lens 44 on perpendicular magnetization 111!41 that is vertically magnetized upward in the figure
Is the temperature of the irradiated area close to the Curie point?
At the same time, an external magnetic field is applied in a direction opposite to the magnetization direction of the perpendicularly magnetized film 41, that is, downward in FIG. The magnetization direction is reversed and information is recorded on the perpendicularly magnetized film 41.

On the other hand, when erasing the information recorded on the perpendicular magnetization film 41, the original magnetization direction of the perpendicular magnetization film 41 (towards the right in FIG. 2)
By applying an external magnetic field in the same direction as the perpendicularly magnetized film 41 and irradiating it with focused laser light, the perpendicularly magnetized film 41 is magnetized upward based on the same principle as during recording, and the information is erased.

Further, when reproducing information recorded on the perpendicularly magnetized film 41, the Kerr effect is usually used. That is, the perpendicular magnetization film 41
Linearly polarized light irradiated onto the surface becomes reflected light with its plane of polarization rotated to the left or right depending on the direction of magnetization (as much as possible - effect).
A reproduced signal is obtained by converting this rotation into a change in light amount using an analyzer or the like.

[Problem to be solved by the invention]

By the way, in order to ensure the recording sensitivity of the perpendicular magnetization film 41,
The thickness of the film is generally required to be 1000 Å or less, and due to its thinness, a large demagnetizing field is generated due to the magnetization of the film itself, reducing recorded magnetization. Therefore, the perpendicular magnetization 11+41 is
In order to maintain recording magnetization, a material must have a high coercive force, but currently known materials with this property have serious drawbacks such as a small Kerr effect and susceptibility to oxidative corrosion. There is a problem in that only an amorphous film of rare earth-transition metal is used, and the selection range of magnetized film materials is narrow.

In addition, conventional magneto-optical recording methods and the devices used therein require the application of a magnetic field perpendicular to the magnetized film, and the applied magnetic field diverges, resulting in small magnetic field distribution and a small magnetic field generator capable of high-frequency modulation. The problem is that it is difficult to configure.

The present invention has been made to solve these problems, and provides a magneto-optical recording system that allows a wide selection of magnetized film materials and uses a small, high-performance magnetic field generation source, and a device used therefor. The purpose is to donate money.

[Means to solve the problem]

The magneto-optical recording method of the present invention is a magneto-optical recording method that records or erases information by irradiating a magneto-optical disk with a light beam to magnetize its magnetized film. The magneto-optical disk device according to the present invention is characterized in that in the magneto-optical recording method, the magneto-optical disk is provided with an in-plane magnetized film that can be magnetized in an in-plane direction. It is characterized by

[Effect]

In the magneto-optical recording method of the present invention, the magnetization direction of the magnetization film of the magneto-optical disk is set not in the thickness direction of the extremely thin magnetization film but in the in-plane direction of the magnetization film. When the distance becomes sufficiently long, the demagnetizing field decreases significantly. Therefore, by recording in the in-plane direction, demagnetization does not occur even in a magnetized film with a low coercive force, and stable information recording can be performed.

Furthermore, regarding the magnetization direction within the plane of the magnetized film, if adjacent magnetic poles with the same polarity of recording magnetization are magnetized so as to face each other, a magnetic field is generated in a direction that cancels out the recording magnetization, so the magnetic poles with the same polarity respond. It is appropriate to record by magnetizing in a direction in which the magnetic field does not move, as this allows more stable information recording and requires less coercive force.

〔principle〕

Next, regarding the recording principle of the magneto-optical recording method according to the present invention,
The explanation will be based on the conceptual diagram of the magneto-optical recording method shown in FIG. In FIG. 2, a laser beam is focused and irradiated by an objective lens 14 onto an in-plane magnetized film 11 that has been magnetized in one direction, for example, rightward in FIG. The temperature is raised to near the Curie point or above the compensation temperature to reduce its coercive force, and the magnetization of the in-plane magnetized film 11 is removed from an in-plane magnetic field generation source, for example, the ring-shaped magnetic head 22 in FIG. 2 in this conceptual diagram. By applying an external magnetic field in the opposite direction, in this conceptual diagram, to the left in FIG. 2, the magnetization direction is locally reversed, and information is recorded in the in-plane magnetized film 11.

On the other hand, when erasing the information recorded in the in-plane magnetization film 1iill, an external magnetic field is applied in the same direction as the original magnetization direction (rightward in FIG. 2) of the in-plane magnetization film 11, and a focused laser beam is applied to the in-plane magnetization film 11. Information is erased by irradiating it using the same principle as during recording.

Further, when reproducing information recorded on the in-plane magnetized film 11, the Kerr effect is usually used. That is, in-plane magnetization l1
The linearly polarized light irradiated to 111 becomes reflected light with its plane of polarization rotated to the left or right depending on the direction of magnetization (vertical Kerr effect or horizontal Kerr effect), and this rotation is converted into a change in light intensity using an analyzer etc. etc. to obtain a reproduced signal.

If, for example, a ring-shaped magnetic head 22 is used as the magnetic field generation source, by combining it with the in-plane magnetized film 11, the magnetic flux 13 will be transmitted from one end of the ring-shaped magnetic head 22, as shown in FIG. 2 of this conceptual diagram. Emitted and in-plane magnetized film
It has a closed magnetic path configuration in which it passes through the ring, enters the other end of the ring-shaped magnetic head 22, and returns, and is suitable for having little magnetic flux leakage and high magnetic flux efficiency. If the magnetic flux efficiency is increased, a smaller number of coil turns or a smaller coil current is required to apply an external magnetic field of the required intensity to the in-plane magnetized film, and high frequency modulation of the magnetic field and miniaturization of the magnetic field generation source are possible.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a schematic diagram schematically showing an example of the configuration of a main part of a magneto-optical disk device according to the present invention, in which reference numeral 21 denotes a magneto-optical disk using an in-plane magnetization film that is magnetized in an in-plane direction. It is. The magneto-optical disk 21 has information recording tracks formed concentrically or spirally, and rotates around its axis at high speed. Both ends of the yoke of the ring-shaped magnetic head 22 are arranged in the radial direction of the magneto-optical disk 21. A magnetic field is applied in the radial direction of the magneto-optical disk 21.

On the other hand, the laser beam generated from the semiconductor laser 23 is transferred to the condensing lens 24, the shaping prism 25, and the beam splitter 2.
6, the in-plane magnetized film of the magneto-optical disk 21 is irradiated with condensed light through the objective lens 27 to raise the temperature of the magnetized film to near the Curie point or above the compensation temperature. It is magnetized depending on the direction of magnetic field application, and information is recorded or erased.

When reproducing information, the linearly polarized light generated from the semiconductor laser 23 passes through the condenser lens 24, the shaping prism 25, the beam splitter 26, and the objective lens 27, and then enters the magneto-optical disk 2.
When a predetermined portion of the in-plane magnetized film 1 is irradiated with light, the plane of polarization of the reflected light rotates depending on the direction of magnetization.

This reflected light is transferred to the objective lens 27, the beam splinter 26,
Beam splinter 28. P by polarization beam splinter 34 via 172 wavelength plate 31 and condensing lens 32.

The light intensity of each separated component is converted into an electrical signal by the photodiodes 33 and 35, and the differential amplifier 36 outputs a signal corresponding to the rotation of the polarization plane from the difference between these two components, and outputs information. is played.

Further, a part of the laser light emitted when recording, reproducing, or erasing information is detected by the photodiode 30 divided into four parts from the beam splitter 28 through the cylindrical lens 29.
Focusing and tracking of the irradiated light is performed.

Note that the schematic diagram shown in FIG. 1 is one embodiment of the present invention,
The invention is not limited to this, and for example, a Wollaston prism, a Savart plate, etc. may be used instead of the polarization beam splinter 34, and various optical system configurations are possible. Also, polarization plane rotation detection means using the Kerr effect can be used. However, it is also possible to obtain a reproduction signal directly without using a differential signal.

Next, regarding the recording principle of the magneto-optical recording method according to the present invention,
The explanation will be based on conceptual diagrams of the magneto-optical recording method shown in FIGS. 2 and 3. In FIG. 2, with respect to the in-plane magnetized film 11 that has been magnetized in advance in one direction, in this example, rightward in FIG.
A laser beam is focused and irradiated by the objective lens 14, and the temperature of the irradiated area is raised to near the cue point or above the compensation temperature to reduce its coercive force, and the in-plane magnetic field source, for example, a ring-shaped magnetic An external magnetic field is applied from the head 22 in a direction opposite to the magnetization direction of the in-plane magnetized film 11, which in this embodiment is directed to the left in FIG. Record.

On the other hand, when erasing the information recorded in the in-plane magnetization 15111, an external magnetic field is applied in the same direction as the original magnetization direction (rightward in FIG. 2) of the in-plane magnetization film 11, and a focused laser beam is applied. Information is erased by irradiating it using the same principle as during recording.

Further, when reproducing information recorded on the in-plane magnetized film 11, the Kerr effect is usually used. That is, the in-plane magnetized film 1
The linearly polarized light irradiated on the magnet becomes reflected light with its plane of polarization rotated to the left or right depending on the direction of magnetization (vertical Kerr effect or horizontal Kerr effect), and this rotation is converted into a change in light intensity using an analyzer etc. etc. to obtain a reproduced signal.

In addition, there are two typical examples of in-plane magnetization directions as shown in Figure 3 (a) and (b), but when magnetization is in the recording track direction as shown in Figure 3 (a), if magnetization occurs in the recording track direction, The magnetic poles are magnetized so as to face each other, and a magnetic field is generated in a direction that cancels out the recorded magnetization, thereby reducing the recorded magnetization. Therefore,
As shown in FIG. 3 (al), the case where the trunk is magnetized in the width direction and the magnetic poles N and S are arranged alternately is more suitable because the magnetic poles of the same polarity do not face each other, and therefore less coercive force is required.

That is, in the magneto-optical disk device according to the present invention, by setting the magnetization direction of the magnetization film of the magneto-optical disk not in the thickness direction of the extremely thin magnetization film but in the in-plane direction of the magnetization film, the magnetic pole N generated at both ends of magnetization is , S becomes sufficiently long, and the demagnetizing field is significantly reduced.

Therefore, by recording in the in-plane direction and the track width direction, demagnetization does not occur even in a magnetized film with a low coercive force, and stable information recording can be performed.

For example, in conventional magneto-optical disk devices, PtMn5b (with θ of 1 to 1.8
°) etc. can be used. In addition, in the conventional rare earth-transition metal amorphous film, the Kerr effect (θk) is 0.2 to 0.4.
It's as small as °.

As a magnetic field generation source, a ring-shaped magnetic head 22 as shown in FIG. It has a closed magnetic circuit configuration in which it enters the other end of the head 22 and returns, with little magnetic flux leakage and very high magnetic flux efficiency.If the magnetic flux efficiency increases, it is possible to apply an external magnetic field of the required strength to the in-plane magnetized film. , a smaller number of coil turns or a smaller coil current is required, making it possible to modulate the magnetic field at high frequencies, and also making it possible to downsize the magnetic field generation source and the magneto-optical disk device.

Furthermore, since the direction of the magnetic field can be easily reversed at a high frequency, overriding by a magnetic field modulation method becomes possible, and the effective transfer speed of recorded information increases.

Furthermore, the ring-type magnetic head has less variation in magnetic field strength with respect to variation in distance from the head, and is effective for magneto-optical disk drives where variation in the distance between the disk and the head is unavoidable due to disk surface runout or the like.

〔Effect of the invention〕

The magneto-optical recording method according to the present invention records or erases information by magnetizing the magnetized film of the magneto-optical disk in the in-plane direction, thereby eliminating the need for a high coercive force in the magnetizing film of the magneto-optical disk, Materials with a high Kerr effect, which could not be used due to their low coercive force, can now be used, expanding the range of material selection for magnetized films, making it possible to select materials with high output and high reliability. In the magneto-optical disk device,
By using a ring-shaped magnetic head that forms a closed magnetic path with an in-plane magnetized film as a magnetic field generation source, magnetic flux efficiency is increased, so the required magnetic field strength can be obtained with fewer coil turns or less coil current, and the magnetic field generation source is miniaturized, making it possible to miniaturize the magneto-optical disk device, and
This makes it easy to reverse the direction of the magnetic field at high frequencies, enables override using the magnetic field modulation method, and has the excellent effect of increasing the effective transfer rate of recorded information.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram schematically showing an example of the main configuration of a magneto-optical disk device according to the present invention, FIGS. 2 and 3 are conceptual diagrams of a magneto-optical recording system according to the present invention, and FIG. 4 is a conceptual diagram of a conventional magneto-optical recording system. 11... In-plane magnetized film 13... Magnetic flux 21... Magneto-optical disk 22... Ring-shaped magnetic head 23.
...Semiconductor laser patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Tomio Kono IL Figure 1 Condolence Figure 2
4 Figure 3 Procedural amendment (Silver magneto-optical recording system and equipment used therein 3, relationship with the case of the person making the amendment Patent applicant location 5-15 Kitahama, Higashi-ku, Osaka Name (21)
1) Representative of Sumitomo Metal Industries Co., Ltd. Yasuo Shingu 4, agent address: Kono Patent Office, No. 207, Nisshin Building, 1-14-22 Shitennoji, Tennoji-ku, Osaka 543 (Telephone: 06-
779-3088 >-:1]-212I "Detailed Description of the Invention" column of the specification and Drawing 6, contents of amendment 6-1 "Detailed Description of the Invention" column + 1) of the specification “Magneto-optical effect” on page 2, line 5
Correct the statement to "magneto-optical effect." (2) On page 2, lines 17-18 of the specification, "Curie point" is corrected to "Curie point." (3) On page 5, line 20 of the specification, the phrase "do not respond" is corrected to "J does not respond." (4) On page 6, lines 10-11 of the book M, the phrase "Curie point" is corrected to "Curie point." (5) On page 7, line 4 of the specification, the word "that is" is corrected to "for example." (6) Delete the phrase "or horizontal car effect" on page 7, line 7 of the specification. (7) On page 7, lines 19-20 of Book t4, the phrase "high frequency modulation also" is corrected to "high frequency modulation and." (8) On page 8, line 11 of the specification, the phrase ``1 application shall be applied'' should be corrected to ``can be applied.'' (9) On page 8, line 16 of the specification, the phrase "Curie point" is corrected to "Curie point." Oat On page 10, lines 9 to IO of the specification, "Curie point" is corrected to "Curie point." (11) In the second line of page 11 of the specification, the word "that is" is corrected to "for example." (I2) Delete the phrase "or horizontal car effect" on page 11, line 5 of the specification. (13) On page 12, line 2 of the specification, the phrase ``in accordance with 1'' is corrected to ``further''. (14) On page 12, line 16 of the specification, the phrase "appropriate magnetic flux" is corrected to "appropriate magnetic flux." 6-2 Drawings Figures 1, 2, and 4 are corrected as shown in the attached drawings. There is no need to make any corrections to Figure 3. 7.Inventory of attached W types + 11 Corrected drawings 1 copy L chest 1 Figure 2 Figure ! 4rA■
3 diagram

Claims (1)

[Claims] 1. In a magneto-optical recording method in which a light beam is irradiated onto a magneto-optical disk to magnetize its magnetized film to record or erase information, the magneto-optical disk's magnetized film is magnetized in the in-plane direction. A magneto-optical recording method characterized by recording or erasing information using 2. The magneto-optical recording method according to claim 1, wherein magnetic poles of the same polarity do not face each other in the in-plane magnetization direction. 3. In a magneto-optical disk device that records or erases information by irradiating a magneto-optical disk with a light beam to magnetize its magnetized film, the magneto-optical disk includes an in-plane magnetized film that is magnetized in an in-plane direction. A magneto-optical disk device characterized by: 4. The magneto-optical disk device according to claim 3, wherein the magnetic field generation source that magnetizes the magnetized film is a ring-shaped magnetic head.