Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Patent
1995-07-25
1997-04-01
Hindi, Nabil
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
369 54, 369 32, G11B 700
Patent
active
056174004
ABSTRACT:
A reproducing power control unit of a magneto-optical recording and reproducing apparatus comprising level detecting means, composed of a diode, a capacitor, a subtractor and a sample hold circuit, for detecting the signal levels of control marks of different lengths on a magneto-optical disk, control data generating means, composed of a divider, for outputting a comparing result between the signal levels, error reference generating means, composed of a CPU and a ROM, for generating a reference value representing a specific relation between the signal levels when a light beam has an optimal reproducing power, reference comparing means, composed of a subtractor, for comparing the comparison result with the reference value, and reproducing power changing means, composed of an operational amplifier and a transistor and a resistor, for changing the reproducing power of the light beam to approximate the comparison result to the reference value. The reproducing power is controlled in such a manner that the relation between the signal levels of various types of marks each having a different length becomes equal to the specific relation represented by the reference value. Accordingly, an aperture which minimizes noise components such as crosstalk is developed, and the probabilities of readout errors are reduced.
REFERENCES:
patent: 5337301 (1994-08-01), Sugiura et al.
patent: 5367509 (1994-11-01), Fukumoto et al.
patent: 5477528 (1995-12-01), Murakami et al.
"Characteristics of read/write on magneto-optical disk (Write control method for high density magneto-optical disk: system)" T. Maeda et al, Technical Report of IEICE. MR92-62 (1992-11), pp. 13-18.
"Read power control method for magnetic super-resolution disk": H. Fuji et al, Proceedings of Magneto-Optical Recording International Symposium '94, J. Magn. Soc. Jpn,, vol. 19, Supplement, No.S1, 1995, pp. 441-442.
Hindi Nabil
Sharp Kabushiki Kaisha
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