JPS6150235A - System and apparatus for erasing and reproducing optomagnetic recording - Google Patents

Abstract

PURPOSE:To attain rewrite of recording information with simple device constitution without switching application direction of an external magnetic field by changing an oscillated laser light intensity of a laser light source corresponding to recording/reproduction/erasure. CONSTITUTION:A laser light source modulating circuit 20 is used for the modulation of the laser light source 6 of an optical head 5 to modulate power of the laser light source 6 in matching with recording/reproduction/erasure. In desiring recording information recorded already on an optomagnetic disc 1, the power level of the laser light irradiated to a magnetic thin film 3 is adjusted to a power level PE at which the magnetizing direction of the already recorded part restores to the initial state. in recording the new signal information succeedingly, the adjustment is performed that the laser light power absorbed in the magnetic film 3 reaches a sufficient level PW to form the magnetization inverting part. A constant magnetic field is applied to the magnetic thin film 3 by a magnetic field generating means 12 in a series of erasure/recording processes as above and the field is not required to be changed throughout recording/reproduction/erasure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magneto-optical recording, reproducing and erasing method and apparatus for reproducing and erasing original magnetic recording using laser light.

(Prior art and its problems) Optical recording systems, especially original disk memory systems, have been used as a type of large-capacity alley memory because they enable high-density, large-capacity recording, as well as non-contact and high-speed access. It has been attracting attention in recent years.Among them, as a medium
nJ3i, hincuBi, MnTiB1.

MnAA! ()e or other crystalline magnetic thin films or Tb,
Gd.

Rare earth metals such as Dy/HO and Pe, Co, Ni
Magneto-optical disk memory using an amorphous magnetic thin film, which is created by combining it with a ferromagnet, has the advantage of being able to rewrite the recorded information, so it is being actively researched in various places. ing.

In conventionally known magneto-optical recording/reproducing/erasing systems and devices, the following operations are performed for recording, reproducing, and erasing information, respectively.

Recording VcFi uses heat generated by laser light.

Focus the laser beam to a minute spot of 1 to 2 μmψ,
The recording medium is irradiated to raise the medium temperature. When recording the temperature of the recording medium, the temperature of the recording medium is raised to a temperature above the temperature of the recording medium, and an externally applied magnetic field is used to form reversed magnetic domains due to the demagnetizing field of the recording medium. When performing compensated temperature recording, the compensation temperature of the recording medium is set near room temperature, the temperature is raised to a certain temperature by laser beam irradiation, the coercive force of the medium is fully utilized, and the reversed magnetic domain is created by an externally applied magnetic field. By the means for forming a recorded binary signal [JroJ
R: Can be recorded in a t-shape depending on the presence or absence of reversed magnetic domains in the medium.

Reproduction is based on the magneto-optical effect (Kerr effect or parad
By effect). In other words, when the plane of polarization of reflected light or transmitted light from the medium rotates in response to the presence or absence of reversed magnetic domains in the recording medium, information is read from the recording medium by utilizing the rotation of the plane of polarization. is irradiated with laser light, and a signal is reproduced from the reflected or transmitted light.

Here, the intensity level of the laser beam used for reproduction is set to a level that does not change the magnetization state of the recording medium.

When erasing recorded information, an external magnetic field is applied with a polarity opposite to that during recording, and a laser beam is uniformly irradiated onto the recording medium with the same intensity as during recording. By applying an external magnetic field, the magnetization state of the recording medium returns to the initial state before distribution.

In the conventional original magnetic recording reproducing erasing method and device,
To rewrite the recorded information, a two-step operation is performed: first, the previously recorded information is erased according to the erasing operation, and then new recorded information is recorded according to the recording operation. At this time, since the direction of the external magnetic field applied to the recording medium is opposite during erasing and recording, means must be provided to switch the direction of the externally applied magnetic field during erasing and recording.

For example, when applying an external magnetic field to the coil (therefore, as shown in FIG. 4), recording and erasing is performed on the magneto-optical disk IK in synchronization with the recording and erasing operations of the laser beam from the female head 5. A method is known in which the direction of the current flowing through the coil 21 is switched by the coil @flow polarity switching means 22.

Furthermore, when applying an external magnetic field using a permanent magnet 23 as shown in FIG. Both methods and devices have the disadvantage that the device configuration is aJA.

(Objective of the Invention) An object of the present invention is to solve the drawbacks of the conventional magneto-optical recording/erasing method and device, and to change the quality of recorded information using a simple device configuration without changing the direction of application of an external magnetic field. The object of the present invention is to provide a new magneto-optical recording/reproducing/erasing method and WL that can perform the following.

(Structure of the Invention) According to the present invention, there is provided a magneto-optical recording/reproducing/erasing method in which a magnetic thin film having perpendicular magnetic anisotropy is used as a recording medium, and information is recorded, reproduced, and erased using a laser beam. There is a recording process in which information is recorded by changing the intensity of the irradiated laser light, a reproduction process in which the recorded information is reproduced by irradiating the recording medium with a laser beam of a constant intensity, and a reproduction process in which the recorded information is reproduced by irradiating the recording medium with a laser beam of a constant intensity. An optical recording/reproducing/erasing method is obtained, which consists of an erasing process in which information is erased as described above, and a constant magnetic field is externally applied to the recording medium through the recording/reproducing/erasing process. , a magnetic field generating means that applies a constant magnetic field to the recording medium, an optical head that irradiates the recording medium with laser light, and a laser light source that changes the intensity of the lost laser light corresponding to the time of recording, reproduction, and erasing. A magneto-optical recording, reproducing and erasing device is obtained, which is characterized in that it is equipped with a laser light source modulation circuit.

(Detailed explanation of the structure) The present invention has solved all the problems of the prior art by adopting the above-mentioned structure.

Hereinafter, details of the present invention will be explained using the drawings. N
Figure g1 shows an example of the configuration of a magneto-optical recording/reproducing/erasing device to which the present invention is applied. In FIG. 1, a magneto-optical disk 1 is formed by forming a magnetic thin film 3 having an axis of easy magnetization perpendicular to the substrate surface on one or both surfaces of a disk 2 made of an organic resin substrate, a glass substrate, or a metal substrate.
It is something.

The mother thin film 3 is a crystalline or amorphous magnetic thin film, for example, 1MnB1. MnCuB1. MnTi
B1゜Crystalline magnetic thin film such as MnAlGe, or S
m.

It is an amorphous fracture film created by a combination of rare earth metals such as Tb, Gd, Dy, and Ho and transition metals such as Fe + COrNi. The magneto-optical disk 1 is rotated at a predetermined speed by a single disk drive motor 4. The optical disc 5 is equipped with an optical system for reproducing and erasing optical recording, and a light detection mechanism. The optical head 5 itself is movable at a predetermined speed in the radial direction of the magneto-optical disk 10, as indicated by the arrow in the figure.

In the optical head 5, 6 is a linearly polarized laser light source, for example, a semiconductor laser is used. 7,8.9
is a beam splitter.

The laser beam focusing lens 10 is an actuator 11
Supported by The magnetic field generating means J2 is installed on the opposite side or on the same side as the laser beam f% source lens via the magneto-optical disk, and uses a combination of a permanent magnet or a coil and a DC power source. The focus error and tracking error signals are detected by the focus error detection amount v: IL element 13 and the tracking error detection light receiving element 14, respectively, and are sent to the servo control circuit 15.
16, becomes a servo signal, and is fed back to the actuator 11. After passing through the polarizing filter 17 , the reproduced signal is detected by the reproduced signal detection light receiving element 18 and amplified by the reproduced signal amplification circuit 19 .

For example, a Grass/Thomson prism is used as the polarizing filter. As a light receiving element for detecting a reproduced signal, for example, PIN7. ) diode, avalanche 7 otodiode is used. A laser light source modulation circuit 2o is used to modulate the laser light source 6, and adjusts the power of the laser light source 6 according to recording, erasing, and reproducing.

Next, the operating method of the magneto-optical recording/reproducing/erasing apparatus having the above structure, particularly an erasing method different from the conventional method, will be explained with reference to FIG.

On the magneto-optical disk 1, there are already 2 sections shown in FIG.
Value code information is recorded along the disc tracks. At this time, the magnetization state of the magnetic thin layer M3 of the magneto-optical disk 1 corresponds to the partial "1" signal indicated by the R line in FIG. It is reversed to AK.

Next, when the recorded information is to be erased, the power level of the laser beam irradiated onto the magnetic thin film 3 is adjusted to a constant power level PmVCIJIA as shown in FIG. This can be adjusted by the laser light source V adjustment circuit 2o.

Px#'i, regardless of the magnetization state of the fk section described above (i.e., presence or absence of magnetization reversal), the magnetization direction is in the initial state ("
0'' signal level).

As shown in FIG. 2(C), by irradiation with the t laser beam power, the magnetic thin film J [the magnetization of 3 is fd in FIG. 2] is brought into the state, and the recorded information is erased.

Next, when recording a new binary signal information ratio, for example, signal information as shown in FIG.
(The laser light source modulation circuit 20 is adjusted so that the laser light source modulation circuit 20 is adjusted so that the laser light source modulation circuit 20 becomes C. FIG. .

It shows the laser beam backlash required to detect focus errors and tracking errors during PRI-i recording. PR is at the same level as the laser light power during reproduction.

When recording is performed with the laser light power shown in FIG. 2(f), the magnetization state of the magnetic R film 3 becomes as shown in FIG. 2 (button).

As described above, in the series of erasing and recording processes, a constant magnetic field Ha is applied to the mother thin film 3 by the magnetic field generating means 12 consisting of a magnetic field applying coil or a permanent magnet.
There is no need to change it throughout recording, playback, and erasure. That is, low recorded information can be erased by adjusting the laser power without receiving an applied magnetic field, and new information can be recorded.

(Example 1) Information was recorded, reproduced, and erased on a magneto-optical disk using the magneto-optical recording, reproducing and erasing device shown in FIG. As a magneto-optical disk, a TbFe film of 700Al was coated on a 120Mψ polycarbonate resin substrate by the snot-vine method.
l! ! A disk formed in the following manner was used. The substrate used was a so-called pre-group substrate in which grooves of @0.8 μm, pitch of 2.5 μm, and depth of 7QOA were formed in advance.

5if2 is applied as a protective film on the TbFe film by vacuum evaporation! 1112QOA has been formed.

FIG. 3 shows the measurement results of erasing characteristics. Tb Fe is applied to the magneto-optical disk by a coil placed behind the disk.
A magnetic field of 175Q6 is applied in the same direction as the magnetization of the wire,
% g 111 /sst: After recording with a laser beam power pw of 1 g of IMHz, the recording track VC was irradiated with a constant laser blur of 4 pg for erasing. In the area A, the recorded signal, that is, l
The Ml-IZ signal was completely erased. - In the region of 10,000 B, the erasing laser power P8 did not completely erase it. Further, since the area Pw of area C is less than the recording threshold value, it is an area where no signal recording is possible.

(Example 2) Using the photomagnetic distribution reproducing and erasing device shown in Example 1 and the optical a%f disk f, Pw = 9.5 mW, Pn = 9.5
"WW PR = 1.0, linear velocity 9 m/sec, and a magnetic field of 175 Qe was applied in the same direction as the magnetization of Tb Fe. Recording and erasing of the signal l fvll (Z) were repeated. Recording and erasing was performed at 105 Qe. No change was observed in the erasing characteristics even after repeating the test several times.

(Effects of the Invention) As described above, the present invention has the following effects compared to the conventional example.

In other words, change the direction of external magnetic field application! Since recording and erasing can be achieved under a constant external field application state without changing the structure, the configuration of the magneto-optical recording/reproducing/erasing device can be simplified. The present invention is not limited to the TbFe film shown as an example as a magneto-optical disk, but can be widely applied to crystalline magnetic thin films and amorphous magnetic thin films for magneto-optical recording.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a magneto-optical recording/reproducing/erasing device to which the present invention is applied, and FIG. 2 (al to fg+ are schematic diagrams showing the operation mode and recording state of each part during erasing and recording. In addition, Figure @3 is a schematic diagram showing the operation mode of each part of the conventional original recording/reproducing/erasing system, which is one of the features of the present invention. Matrix thin film, 4Vi disk drive motor. 5 is an optical head, 6 laser light sources, 7, 8, 9 are beam splitters, 10 is a laser source beam focusing lens, 11 is an actuator, 12 is a magnetic field generating means , 13 is a light receiving element for focus error detection, 14
15.161 Receiving member for tracking error detection
-t: Servo control circuit, 17i! Unbalanced C filter,
Reference numeral 18 indicates a reproduction signal detection quantity f, i, 19 indicates a reproduction signal amplification circuit, 20 indicates a laser light source modulation circuit, 21 coils, 22 indicates a coil power supply and coil current polarity switching device, and 23 permanent magnets. This is a magnetic field generating means based on Agent もπ± Same plt publication 71 Figure 1: Magneto-optical disk 20: Laser light source modulation circuit 5
: Optical head 12 : Magnetic field generating means 72 Figure (9) Magnetization state. 73 Figure Recording power - Pw (mW) 74 Figure 1: Magneto-optical disk 5: Optical head 21: Coil A-5 Figure 1: Magneto-optical disk 5: Optical head 23: Magnetic field generating means O Figure 6 +01 During recording (b) When erasing -17,1-

Claims (2)

[Claims] (1) A magneto-optical recording, reproducing and erasing method in which a magnetic thin film with perpendicular magnetic anisotropy is used as a recording medium and information is recorded, reproduced and erased using a laser beam, and the intensity of the laser beam irradiated to the recording medium is varied. a recording process of recording information by
A constant magnetic field is applied to the recording medium from the outside through a reproduction process in which recorded information is reproduced by irradiating the recording medium with a laser beam of a constant intensity, and an erasing process in which the recorded information is erased by irradiating the recording medium with a laser beam of a constant intensity. A magneto-optical recording, reproducing and erasing method characterized by applying an electric current to the magnetic field. (2) A recording medium, a magnetic field generating means that applies a constant magnetic field to the recording medium, an optical head that irradiates the recording medium with a laser beam, and an oscillating laser of a laser light source during recording, reproduction, and erasing. 1. A magneto-optical recording/reproducing/erasing device comprising: a laser light source modulation circuit that changes light intensity;