Optical disc apparatus

Assignee: Sony Corp

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Filing: 1993-07-21

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Granted: —

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Expires: 2013-07-21

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Abstract

Abstract In an optical disc apparatus for recording/reproducing desired information, e.g. a "write once, read many times" optical disc system, it is desired to securely detect speed information and address data recorded in a pregroove, even when the position of incidence of a light beam (L1) with respect to a light receiving element (24) has been changed. To this end, output signals (SA+SD, SB+SC) of light receiving surfaces of an optical pickup (6) adjacent to each other in the received radial direction of an optical disc (2) have their relative signal levels corrected so that the signal levels of RF components mixed into these output signals are equalized to each other. A difference signal thereof is then generated to recover the speed information and address data. <IMAGE>

Inventors

👤 Shinichiro c/o Intellectual Property Div. Iimura

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-09 07:25

CPC Classifications

G; G11; G11B; G11B7/00; G11B7/24; G11B7/26; G11B7/08; G11B7/09; G11B7/0943

Claims Analysis

Total Claims: 5

Claim 1

Independent Claim 227 words

An optical disc apparatus for detecting meandering of a pregroove of an optical disc (2), said pregroove meandering on the basis of control information (ATIP) for use in recording/reproducing a desired information signal from said optical disc, said optical disc apparatus comprising: (i) a light source (10) for emitting a light beam (L1); (ii) an optical system (6) for concentrating said light beam onto an information recording surface of said optical disc and for receiving reflected light of said light beam; (iii) a light receiving element having a light receiving surface (24) divided into at least first and second light receiving surfaces (AD, BC) in a radial direction of said optical disc, said light receiving element receiving said reflected light at said optical system and outputting first and second output signals (SA+SD, SB+SC) respectively from said first and second light receiving surfaces; (iv) difference signal generation means (40) for generating a difference signal (SW) from between said first and second output signals; and (v) information detection means (44, 46) for detecting said control information from said difference signal; characterised in that said difference signal generation means (40) is responsive to said first and second output signals for correcting relative signal levels of said first and second output signals so as to substantially equalize signal levels of said information signal mixed into said first and second output signals.

Claim 2

Dependent Claim 43 words

Apparatus according to claim 1, wherein said difference signal generation means (40) is operative to detect envelopes of said first and second output signals and to correct relative signal levels of said first and second output signals on the basis of said envelopes.

Claim 3

Dependent Claim 55 words

Apparatus according to claim 2, wherein said difference signal generation means (40) is operative to clamp said first and second output signals at clamping circuits (58, 60) and then to peak hold said first and second output signals at peak hold circuits (62, 64) to detect the envelopes of said first and second output signals.

Claim 4

Dependent Claim 12 words

Apparatus according to claim 1, wherein said control information comprises time information.

Claim 5

Dependent Claim 12 words

Apparatus according to claim 1, wherein said control information comprises speed information.

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