Optical disk having intertrack heat conduction suppression

Details Optical disk having intertrack heat conduction suppression Optical disk having intertrack heat conduction suppression

1992-10-08

1994-10-04

Dzierzynski, Paul M.

Dynamic information storage or retrieval

Storage medium structure

Optical track structure

369277, G11B 724

Patent

active

053532775

ABSTRACT:
To increase the track density, that is, to improve the recording density of the optical disk of ultra-high resolving power reproduction type, grooves 4 are formed in a transparent substrate 2; phase pits 1 are formed on groove bottom portions 5 and land portions 6 of the grooves; and further a material layer 3 is laminated. A polycarbonate substrate is used as the transparent substrate 2. The material layer 3 is formed of such a material that the state is partially changed due to heat of the reading light in the optical spot of the reading light but returned to the original state after the reading light has passed, and in addition the reflection factor of the material is changeable according to the state change. The material layer 3 is a ternary compound of Ge.sub.2 Sb.sub.2 Te.sub.3. The thermal conductivity of the transparent substrate 2 is smaller than that of the material layer 3. The temperature of the material layer 3 rises in the laser spot according to the light intensity distribution of the laser, so that the reflection factor changes partially to enable data read operation. The heat conduction suppression due to the presence of the stepped portions of the grooves 4 sharpens the temperature gradient, so that the range in which the reflection factor is increased due to the state change of the material layer 3 can be reduced, thus decreasing the track interval distance and thereby increasing the track density.

REFERENCES:
patent: 4731755 (1988-03-01), Bjorklund et al.
patent: 4983505 (1991-01-01), Higuchi et al.
patent: 5115424 (1992-05-01), Nakajima et al.
patent: 5199023 (1993-03-01), Yamamoto et al.

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