JPH01276454A - Initializing method for magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To reduce a noise and to shorten an initializing time by simultaneously erasing a recording track and a guide track with using an erasing beam whose spot diameter is large. CONSTITUTION:A bias coil 13 to form an erase magnetic field is provided in the upper direction of a magnetic disk 1 which has a guide channel 2 and a recording track 3. Then, in a condition that the erase magnetic field is formed by a current in this coil 13, both semiconductor lasers 4 and 8 are emitted. An output light 1 of this laser 4 is condensed through a deflecting beam splitter 6 and a diaphragm lens 7 on a magneto-optical recording disk 1 and a spot L is formed. The reflected light of this disk 1 is successively passed through the lens 7, the splitter 6, a filter 10 and a diaphragm lens 11, converted to an electric signal by an optical detector 12 and sent to an automatic focusing/ tracking actuator 14. A light (m) from the laser 8 is condensed on the disk 1 samely as the light 1 and a spot M, whose beam diameter is larger than a track pitch width, is formed. Then, the recording track and guide track are simultaneously erased with using the erase beam of the large diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for initializing a magneto-optical recording medium in the form of a disk or a card, in which signals are recorded and reproduced by the magneto-optic effect.

[Conventional technology]

A magneto-optical type is known as a memory medium capable of high-density recording. As shown in FIG. 2, this type of medium has a guide groove (group part) 2 for tracking control and a signal recording track (land part) 3, and this signal recording track 3 is located between the guide grooves 2. A so-called groove-to-groove recording is performed. Information is recorded and reproduced by moving the beam 16.

When new information is to be recorded on a disk before use or a disk on which information has been recorded, the direction of magnetization of the magnetic layer of the recording track 3 must be uniformly aligned in the erasing direction and initialized.

Conventionally, this initialization involves applying a magnetic field in the erasing direction to the magneto-optical recording medium using a bias coil, and in this state, irradiating a continuous beam with an optical output equal to or greater than that during recording to generate a magnetic field. By increasing the temperature of the layer,
This is done by lowering the coercive force of that part and aligning the direction of magnetization with the direction of the above-mentioned magnetic field.

(Problem to be Solved by the Invention) However, in conventional erasing, the magnetization of the magnetic layer in the guide groove (group portion) is not aligned in the erasing direction.
The magnetization mismatch in this part appears as noise in the reproduced signal, and as a result, the C/N ratio (Carrier to
There is a problem in that the signal-to-noise ratio (signal-to-noise ratio when a single-frequency signal is recorded on a disk, reproduced, and subjected to spectrum analysis using a measurement system of a certain band) is reduced.

Further, as a method to solve this problem, it is conceivable to switch the tracking polarity and irradiate the beam onto the guide groove (guide track) so that this portion is also erased. However, this method has a problem in that it requires twice as much initialization time as the conventional method.

[Means to solve the problem]

The method for initializing a magneto-optical recording medium of the present invention is to perform servoing of the optical system using a preceding tracking control beam, and then follow this control beam to irradiate the recording track and the guide tracks on both sides of the erase track. A beam is used to align the magnetization direction of the entire surface of the disk in the direction of the erased state in one erase.

[Effect]

By erasing the recording track and the guide track at once using a large spot type erasing beam, the initialization time can be shortened. In addition, this erasing beam and the tracking and focusing beam (reproduction beam) are focused onto the disk through a common optical lens.
In addition, by utilizing the wavelength difference between the respective beams, the reflected light of the playback beam is selectively extracted and servo information can be obtained. Accurate initialization can be performed with an erasing beam that follows.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an initialization device to which an embodiment of the present invention is applied.

A bias coil 13 is provided above the optical disk 1 having a guide groove 2 and a recording track 3 for forming an erasing magnetic field. Further, as laser beam irradiation means, semiconductor lasers 4 and 8, a condensing lens 5.9, and a polarizing lens 6 are used.
, a filter 10, an aperture lens 7.11, a photodetector 12, and an autofocus/tracking actuator 14. The diaphragm lens 7 is held movably in two axes: an optical axis direction and a direction perpendicular to the track. The semiconductor laser 4 emits a laser beam 2 with a wavelength of 830 mm, and the semiconductor laser 8 emits a laser beam m with a wavelength of 780 mm.
is emitted.

Next, the operation of this embodiment will be explained.

A current is passed through the bias coil 13 to form an erasing magnetic field,
In this state, both semiconductor lasers 4 and 8 are caused to emit light.

The output light 2 of the semiconductor laser 4 is sent to a polarizing beam splitter 6.
The light is focused onto the magneto-optical recording disk 1 via the aperture lens 7 to form a spot L. Spot L (beam I
The reflected light from the magneto-optical recording disk 1 (L) is passed through the aperture lens 7. Polarizing beam splitter 6, filter 10. The light passes sequentially through an aperture lens 11 and is guided to a photodetector 12. The photodetector 12 is composed of a 4-divided PIN diode,
Photoelectric conversion is performed here, and the resulting electrical signal is sent to the autofocus/tracking actuator 14. In response to this, the actuator 14 controls the aperture lens 7 in the optical axis direction and in a direction perpendicular to the track to perform force adjustment and tracking adjustment.

On the other hand, the light m emitted from the semiconductor laser 8 forms a spot M having a beam diameter equal to or larger than the track pitch width on the magneto-optical recording disk 1 via the polarizing beam splitter 6 and the aperture lens 7 like the light 2. . This light spot M
always irradiates at least the recording track 3 and the guide track inside it. Also, this spot M
The reflected light is blocked by the filter 10 and the photodetector 12
will not be reached. Therefore, the force adjustment and tracking adjustment of the aperture lens 7 are performed based on the reflected light of the light 1. However, since the light m is focused on the magneto-optical recording disk 1 by the aperture lens 7 like the light 2,
The light spot L and the light spot M move simultaneously and by the same amount in the direction perpendicular to the track, and the light spot M follows the light spot L and moves accurately while being subjected to force steering and tracking servo. As a result, the direction of magnetization is uniformly aligned with the direction of the magnetic field generated by the bias coil 13, and initialization is performed.

With the above configuration, while applying a magnetic field by the bias coil 13, the optical output for tracking control is 1 mW, the erasing power is 10 mW, and the disk rotation speed is 180 Orp.
When erasing was performed with m, the noise level of the reproduced signal was lower than when erasing with the same beam diameter as in conventional reproduction. In addition, since the recording track and the guide track can be erased by -degree erasure, the initialization time can be shortened.

〔Effect of the invention〕

As explained above, the present invention erases the recording track field and the guide track at once using a large-diameter light beam that is precisely controlled by forcing and tracking, thereby reducing noise and reducing the initialization time. It becomes possible to shorten the length.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an initialization device to which an embodiment of the present invention is applied, and FIG. 2 is a diagram showing the basic configuration of a magneto-optical recording medium (disk). 1......Magneto-optical disk, 2...
...Guide groove, 3... Recording track, 4.8...
... Semiconductor laser, 5.9 ... Condensing lens, 6 ... Polarizing beam splitter, 7.1
1...Aperture lens, 12...Photodetector, 13...Bias coil, 14...
...Automatic focus/tracking actuator, L, M...Light spot.

Claims (1)

[Claims] 1. A magneto-optical recording medium having tracking control guide grooves and a signal recording track located between the tracking control guide grooves is placed in a magnetic field formed in the erasing direction, and in this state. , irradiate the signal recording track and the guide grooves on both sides thereof with light, move the light and the magneto-optical recording medium in a predetermined direction, and irradiate the entire surface of the medium with the light to change the direction of magnetization according to the magnetic field. A method for initializing a magneto-optical recording medium by aligning the recording track in a direction, the method comprising: performing tracking and focusing servo with a first beam having a spot diameter matching the pitch width of the recording track; A second beam that is larger than the first beam and follows the first beam illuminates the signal recording track and the guide grooves located on both sides thereof, thereby changing the direction of magnetization of the illuminated portion by the magnetic field. A method for initializing a magneto-optical recording medium by aligning it in the direction of . 2. A magneto-optical recording medium having a tracking control guide groove and a signal recording track located between the tracking control guide grooves is placed in a magnetic field formed in the erasing direction, and in this state, light is applied to the signal recording medium. The track and the guide grooves on both sides thereof are irradiated, the light and the magneto-optical recording medium are moved in a predetermined direction, and the entire surface of the medium is irradiated with the light to align the direction of magnetization with the direction of the magnetic field and initialize it. A method for initializing a magneto-optical recording medium in which light emitted from a first light source is focused onto the signal recording track using a lens, and the focused beam is used as a tracking and focusing control beam. At the same time, light emitted from a second light source and having a different wavelength from the light emitted from the first light source is guided to the lens, and this lens is used in common to servo the lens. Initializing a magneto-optical recording medium by illuminating at least a predetermined pitch width or more of a signal recording track and the guide grooves located on both sides thereof, thereby aligning the direction of magnetization of the illuminated portion with the direction of the magnetic field. method. 3. The method for initializing a magneto-optical recording medium according to claim 2, wherein the beam emitted from the first light source and used for tracking and focusing control has the same spot diameter as a reproduction beam used for signal reproduction.