Patent EP0623921A1 successfully refreshed from Google Patents.
EP0623921A1
Expired / Lapsed
EP
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Signal detecting method and signal detecting apparatus
Assignee: Sony Corp
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Filing: 1994-04-05
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Granted: —
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Expires: 2014-04-05
Abstract
Abstract Outputs of first and second photodetectors (1,2) are supplied to first and second normalizing circuits (8,9) and are also added by an adding circuit (7). An output of the adding circuit (7) is supplied to the normalizing circuits (8,9). By the output supplied from the adding circuit (7) to the normalizing circuits (8,9), the outputs supplied from the photodetectors (1,2) to the normalizing circuits (8,9) are normalized. A subtraction is performed between the outputs of the normalizing circuits by a subtracting circuit (11).
Inventors
- 👤 Hiroshi Ogawa
- 👤 Shinichiro Iimura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:39
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0943; G11B7/0938
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
97 words
A signal detecting method of detecting additional information of a optical disc which was wobble recorded on a track, comprising the steps of: adding outputs of first and second photodetectors (1,2) divided in the tangential direction of said track, thereby obtaining a reproduction RF signal; normalizing said outputs of said first and second photodetectors (1,2) by said RF signal so as to reduce an influence by a recording signal; and performing a subtraction between said normalized outputs of said first and second photodetectors (1,2), thereby obtaining said additional information of the optical disc which was wobble recorded.
Claim 2
Dependent Claim
77 words
The signal detecting method according to claim 1, wherein said normalizing step comprises the steps of: detecting said reproduction RF signal; performing gain control of outputs of said first and second photodetectors (1,2), respectively; detecting the levels of said outputs of said gain control, respectively; comparing said detected levels and the level of said reproduction RF signal, respectively; and controlling outputs of said first and second photodetectors (1,2) on the basis of an output of said comparison.
Claim 3
Dependent Claim
18 words
The signal detecting method according to claims 1 or 2, wherein said optical disc is a CD-R disc.
Claim 4
Dependent Claim
124 words
A signal detecting apparatus to detect additional information of a optical disc which was wobble recorded on a track, comprising: first and second photodetectors (1,2) divided in the tangential direction of said track; adding means (7) for adding outputs of said first and second photodetectors (1,2), thereby obtaining a reproduction RF signal; first and second normalizing means (8,9) for normalizing said outputs of said first and second photodetectors (1,2) by said reproduction RF signal so as to reduce an influence by a recording signal; and subtracting means (11) for performing a subtraction between said outputs of said first and second photodetectors (1,2) normalized by said first and second normalizing means (8,9), thereby obtaining said additional information of the optical disc which was wobble recorded.
Claim 5
Dependent Claim
96 words
The signal detecting apparatus according to claim 4, further comprising first detecting means (41) for detecting said reproduction RF signal, said first and second normalizing means (8,9) comprising; first and second variable gain means (21,22) for performing gain control of said outputs of said first and second photodetectors (1,2), respectively; second and third detecting means (22,32) for detecting outputs of said first and second variable gain means (21,31), respectively; and first and second comparing means (23,33) for comparing outputs of said second and third detecting means (22,32) and an output of said first detecting means (41).
Claim 6
Dependent Claim
18 words
The signal detecting apparatus according to claims 4 or 5, wherein said optical disc is a CD-R disc.
References Cited (Backward Citations)
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