Title: Information recording and retrieval apparatus

Abstract: An information signal is recorded on information tracks wobbling along concentric circles or a spiral line on a recording disc in superposed relation with a standard signal whose frequency varies depending on the recorded position on the disc. Desired information can be selectively reproduced accurately at a high speed by applying an external signal having the same frequency as that of the standard signal recorded on the recording disc together with the desired information, comparing the frequency of the standard signal being reproduced with that of the externally applied signal, selecting the desired information track on the basis of the result of frequency comparison for reproducing the desired information, and after the selection of the desired information track, carrying out fine tracking control while comparing the envelope of the reproduced information signal with the reproduced standard signal, so that the reproducing beam spot can accurately track the desired information track.

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Inventors: Maeda, Takesi (Kokubunji, JA)
Kohmoto, Mahito (Tokyo, JA)
Yonezawa, Seiji (Hachioji, JA)

Application Number: 654966
Filing Date: 1976-02-03
Publication_date: 1978-01-03
Assignee: Hitachi, Ltd. (JA)
Primary Class(es): 369/44.13 250/202, 360/72.1, 360/77.06, 369/30.03, 369/44.28, 369/44.31, 369/111, 369/272
Other Classes:
US Patent Ref:

3126535	Mar, 1964	Streeter	360/77.
3662363	May, 1972	Chertok	179/100.
3845500	Oct, 1974	Hart	360/77.
3876827	Apr, 1975	Janssen	179/100.
3931457	Jan, 1976	Mes	360/72.
3931460	Jan, 1976	Watson	179/100.

Other Refs:
Primary Examiner: Konick, Bernard
Assistant Examiner: Faber, Alan
Attorney: Craig & Antonelli