Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam
Patent
1989-06-06
1991-10-29
Levy, Stuart S.
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Magnetic field and light beam
369 54, 369 58, 369 59, 369 47, G11B 712, G11B 1112, G11B 1304
Patent
active
050620916
ABSTRACT:
A magneto-optical recording medium having a magnetic film having magnetization normal to a plane thereof and having a number of prepits preformed in an optically detectable form at a predetermined interval along a track is prepared. Areas between the prepits are defined as recording areas in which data is to be recorded. A clock signal having a predetermined frequency is generated in synchronism with a reproduced signal corresponding to the prepits of the magneto-optical record medium in response to the reproduced signal. A radiation pulse having an energy corresponding to a signal having a predetermined pattern is irradiated to the magneto-optical record medium in accordance with the clock signal to record the predetermined pattern in at least one of the recording areas prior to code data to be recorded. A phase difference (.delta..sub.2) between the reproduced signal corresponding to the recorded predetermined pattern and the clock signal is detected and a difference (.delta..sub.1 -.delta..sub.2) between the phase difference (.delta..sub.2) and a phase difference (.delta..sub.1) between the reproduced signal corresponding to the signal recorded in the recording area and the clock signal is detected. The clock signal is corrected in accordance with the detected difference.
REFERENCES:
patent: 4698697 (1987-10-01), Okano
patent: 4761775 (1988-08-01), Murakami
patent: 4819218 (1989-04-01), Barnard
Extended Abstract (the 34th Spring Meeting, 1987), the Japan Society of Applied Physics and Related Societies, No. 3, 28P-ZL-3.
"Operating Margins for Magnetic-Optic Recording Materials with Direct Overwrite Capability", Shieh et al., IEEE Trans. on Magnetics, vol. MAG-23, No. 1, Jan. 1987, pp. 171-173.
Maeda Takeshi
Ohta Norio
Suzuki Yoshio
Takahashi Masahiko
Hitachi , Ltd.
Levy Stuart S.
Nguyen Hoa
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