Magneto-optic memory apparatus with defect detection of recordin

Details Magneto-optic memory apparatus with defect detection of recordin Magneto-optic memory apparatus with defect detection of recordin

1987-07-08

1989-11-07

Faber, Alan

Dynamic information storage or retrieval

Storage or retrieval by simultaneous application of diverse...

Magnetic field and light beam

369 54, 369 58, G11B 1112

Patent

active

048797030

ABSTRACT:
A magneto-optic memory apparatus is disclosed in which a laser beam is focused on a recording medium having a perpendicularly-magnetized film, the intensity of said laser beam is caused to correspond to reproducing, recording and erasing operations, an external magnetic field is applied to the recording medium at least in recording and erasing periods so that the magnetic field in the recording period is opposite in direction to the magnetic field in the erasing period, a light quantity signal corresponding to the light quantity reflected from the recording medium and a magnetization signal corresponding to data recorded on the recording medium are produced by using the reflected light from the recording medium, at least one of the light quantity signal and the magnetization is amplified by a variable gain amplifier so that an amplified value in the erasing period is nearly equal to an amplified value in the reproducing period, a defect on the recording medium is detected from the output of the variable gain amplifier in the erasing period, and defect information thus obtained is utilized to record data in a non-defective region of the recording medium.

REFERENCES:
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patent: 4733385 (1988-03-01), Henmi et al.
patent: 4742505 (1988-05-01), Takeuchi et al.
Ojima et al., "Compact Magneto Optical Disk for Coded Data Storage", Applied Optics, vol. 25, No. 4, 2/15/86, pp. 483-489.

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