Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Patent
1996-06-05
1998-10-13
Tran, Thang V.
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
369100, 369 4426, 3692753, G11B 700
Patent
active
058222871
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an optical recording method for recording signals on a disc-shaped recording medium using a laser light beam, an optical recording device employing the optical recording method, and an optical recording medium on which signals have been recorded by the optical recording device.
BACKGROUND ART
Among the existing types of the disc-shaped optical recording media, there are a phase-change type optical disc and a magneto-optical disc as a write-once or overwrite (reversible) optical disc. Among recording light sources in optical recording devices employing these optical discs, there is known a semiconductor laser for recording signals on the optical disc and for erasing the recorded signals. The laser light beam radiated from the semiconductor laser may be converged on the optical disc as a small-sized spot with a diameter not larger than 1 .mu.m.
Among replay-only optical discs, there is a CD-ROM employing a compact disc (CD) as a read-only memory. These CD-ROMs can be duplicated in large quantities. It is contemplated at present to record, on the replay-only optical discs capable of being duplicated in large quantities, such as CD-ROMs, information data for identifying these replay-only optical discs, for example, information data for discriminating whether or not the optical disc is an illicitly duplicated disc, in addition to the information signals, such as audio.
The laser light radiated by the semiconductor laser has a wavelength of 780 nm and is free from ablation. Thus it is not possible to produce a laser light output of an intensity capable of directly recording signals on the replay-only optical disc. Thus, if the identification information is to be recorded on the replay-only optical disc, it is not possible to minutely record the identification information on the replay-only optical disc using the semiconductor laser customarily used as the recording light source.
In view of the above-depicted status of the art, it is an object of the present invention to provide an optical recording method for recording the identification information proper to an optical medium on the recording medium and for reading out the identification information using an optical pickup configured for reading out the information signals recorded on the optical recording medium, an optical recording device for carrying out the optical recording method, and an optical recording medium having the subsidiary information recorded thereon by the optical recording device.
DISCLOSURE OF THE INVENTION
An optical recording method for recording pre-set information on an optical recording medium according to the present invention includes the steps of generating a UV laser light of a wavelength absorbed by the optical recording medium and radiating the UV laser light, and modulating the intensity of the UV laser light for recording the subsidiary information different from the pre-set information recorded in an information recording area of the optical recording medium in an area other than the information recording area.
An optical recording apparatus for recording pre-set information on an optical recording medium according to the present invention includes a laser light source for generating a UV laser light of a wavelength absorbed by the optical recording medium and radiating the UV laser light, means for modulating the intensity of the UV laser light from the laser light source, spot position control means for being moved on the optical recording medium for deciding the position of a spot of the UV light beam converged on the optical recording medium, and scanning means for scanning the optical recording medium with the spot. The subsidiary information different from the pre-set information recorded in an information recording area of the optical recording medium is recorded in an area other than the information recording area.
An optical recording medium having the pre-set information recorded thereon according to the present invention includes an information recording area having
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patent: 5325348 (1994-06-01), Maeda et al.
patent: 5400319 (1995-03-01), Fite et al.
Patent Abstracts of Japan, vol. 18, No. 417 (P-1781), Aug. 4, 1994, JP-A-06 124474, Victor Co of Japan, May 6, 1994 *abstract*.
Database WPI, Week 9125, Derwent Publications Ltd., London, GB; JP-A-03 110193, Toa Gosei Chem Ind Ltd, May 10, 1991 *abstract*.
Kubota Shigeo
Oka Michio
Sony Corporation
Tran Thang V.
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