Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1977-04-08
1980-09-16
Moffitt, James W.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
3581285, 1791003V, 1791003D, 360 77, 346108, 250202, 274 46R, H04N 576
Patent
active
042231876
ABSTRACT:
In order to record information spirally on a disk and to reproduce the recorded information accurately without any contact, at the recording, an information signal and a predetermined signal for synchronous detection are added together, the resultant signal is subjected to frequency modulation and, while a laser beam intensity-modulated by the frequency-modulated signal is minutely swung in the radial direction of the rotating disk at the same frequency as that of the synchronous detection signal, it is caused to impinge on the disk to thereby record the information spirally on a recording medium of the disk without any contact. During the reproduction, as the disk is being rotated, a light spot is caused to impinge along an information groove formed on the disk, and reflected light or transmitted light from the disk is detected in the form of an electric signal. A synchronous detection signal is derived from the electric signal and an envelope signal of the electric signal is synchronously rectified by the use of the snychronous detection signal to thus detect the offset between the light spot and the information groove and, as the offset is being corrected, the information signal is reproduced.
REFERENCES:
patent: 1917003 (1933-07-01), Williams
patent: 2851521 (1958-09-01), Clapp
patent: 3860766 (1975-01-01), Mori
patent: 3931460 (1976-01-01), Watson
Fukuhara Akira
Kato Keizo
Tomura Teruichi
Umemoto Masuo
Yonezawa Seiji
Faber Alan
Hitachi , Ltd.
Moffitt James W.
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