JPS5925290B2 - magneto-optical recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magneto-optical recording device that records and reproduces information using a laser beam.

In general, magneto-optical recording devices capable of high-density recording have a recording track width on the order of micrometers, and because recording and reproduction are performed using a narrowly focused laser beam, the laser beam deviates from the recording track and transfers data to other recording tracks. It was necessary to prevent the data from being recorded or played back.

For this purpose, it was necessary to use a very precise optical system or to provide some kind of guide track.

Conventional guide tracks have been considered to include (1) one that utilizes the recording track itself, and (2) one that uses a groove as a guide track on the recording surface in advance, separate from the recording track. However, although the former method can be effectively used in a magneto-optical recording device that only performs playback, it cannot be used in a magneto-optic recording device that can add new information to areas where no information is recorded.

However, in the latter case, the process for manufacturing the magneto-optical recording device becomes complicated, there are restrictions on the materials used as the recording medium, and the recording density is reduced only in the guide track portion. In other words, both the former and the latter have drawbacks when applied to magneto-optical recording devices.

The present invention has been made in view of the above-mentioned conventional drawbacks, and its purpose is to minimize the decrease in recording density in a magneto-optical recording device, and to use a relatively simple optical system to eliminate laser beams during recording and reproduction. The goal is to ensure that the data does not deviate from the recording track.

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

FIG. 1 is a side view of a recording medium of one embodiment of a magneto-optical recording device according to the present invention, and FIG. 2 is an enlarged plan view of a recording portion.

In the figure, 1 is a glass or plastic disk. GdDy, which is an amorphous magnetic material, is provided on the upper surface of the disk 1.
A Fe-based thin film 2 is formed, and a 5102 protective film 3 is further formed on its upper surface. The above GdDyFe thin film 2 has A
The card bits 4 are formed on the same track as the magnetic recording track 5 by heating with a laser beam at a temperature above the crystallization temperature of, for example, about 35 OOC.

Here, the reason why guide bits are formed when an amorphous magnetic material is crystallized by heating it at a temperature higher than the crystallization temperature will be explained.

Figure 3 is a characteristic diagram showing the wavelength dependence of transmittance of a GdDyFe-based thin film in an amorphous state and a crystalline state (the characteristics are shown for a film in which an SlO2 film is formed as a protective film). .

As is clear from the figure, if the GdDyFe thin film is crystallized from an amorphous state, the wavelength of the He-Ne laser beam (6
(328 people), the transmittance increased from 2.1% to 3.4% compared to the amorphous state. Therefore, by detecting the reflected light of the laser beam, the position of the crystalline state part can be easily detected, and by controlling the irradiation position of the laser beam based on this detection, the irradiation position of the laser beam can be accurately placed on the recording track. can be followed. As mentioned above, since the crystallization temperature is quite high, the magnetic recording track 5 is irradiated with, for example, a laser beam, and the recording bits 6 are formed at a temperature of about 100°C.
Even if thermomagnetic recording is repeated, stable recording can be performed without crystallization in the recording bit 6 portion. The guide bit pattern shown in FIG. 2 is a conventional guide track 7 formed along the magnetic recording track 5 (fourth
It is clear from the figure that it is superior in terms of recording density compared to (see figure).

FIG. 5 shows another embodiment of the guide bit pattern shown in FIG. 2. In FIG. 5, the pattern of the guide track bit 4 is adapted to the characteristics of the light receiving system. Furthermore, if the bits of the guide track are swung in the radial direction at a specific frequency in advance when forming the bits of the guide track, tracking can be performed by warping without adding any special mechanism to the light receiving system. Next, regarding the reading of information, linearly polarized laser light is irradiated onto the recording surface, and the magnetic recording base 6 is detected by rotating the plane of polarization of reflected light or transmitted light (Farade effect or Kerr effect). The guide bit 4 can be detected as a change in the amount of light.

Note that in the above embodiment, GdDy was used as the amorphous magnetic film.
Although an Fe-based thin film is used, any material may be used as long as the recording temperature is lower than the crystallization temperature and the transmittance or reflectance changes with crystallization.

As described above, according to the present invention, portions having different light transmittances (or reflectances) having a width approximately equal to the width of the reversible memory track are intermittently formed on the reversible memory track in an amorphous magnetic material. Due to this structure, the narrowly focused laser beam does not come off the reversible memory track.
Recording and reproduction can be performed extremely well.

Moreover, it is also possible to form the guide means using the same material (amorphous magnetic material) as the reversible memory by simply heating and crystallizing it, and in that case, the manufacturing process can be extremely simplified. In addition, we intermittently formed on the reversible memory track line sections with different light transmittances (or reflectances) having a width approximately equal to the width of the reversible memory track line as guide information. Since the memory tracks can be formed more densely than those formed along the memory tracks, the recording density can be dramatically improved.

[Brief explanation of the drawing]

FIG. 1 is a partial side view of an embodiment of a magneto-optical recording device according to the present invention, FIG. 2 is a plan view of the same portion, and FIG. 3 is a GdDy
A characteristic diagram of the Fe-based thin film, FIG. 4 shows a partial plan view of a conventional magneto-optical recording device, and FIG. 5 shows a partial plan view of another embodiment of the magneto-optic recording device according to the present invention. In the figure, 1: disk, 2: GdDyFe thin film, 3: SiO
2 protection, 4: guide bit, 5: magnetic recording track, 6
:Record bit, 7 reguide track.

Claims (1)

[Claims] 1 Light transmittance (or reflectance) of a width approximately equal to the width of the reversible memory track line intermittently on the reversible memory track line in the disc-shaped amorphous magnetic material
A magneto-optical recording device characterized in that a different portion is formed, and the different portion is used as guide information for preventing a laser beam from deviating from the reversible memory track line.