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US5172355A
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Photo-detecting device including offset correction
Assignee: Pioneer Corp
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Filing: 1991-05-22
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Granted: 1992-12-15
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Expires: 2011-05-22
Abstract
Abstract In the photo-detecting device, the light receiving surface of the light receiving element is divided into four sections A, B, C, D in the direction of tracking. To detect any tracking error, the quantities of received light on these four light receiving sections are used to calculate {(A+B)-(C+D)}-α{(A-B)+(C-D)}, where α is an adjustable value such as a variable resistance. Since this provides a true tracking error which does not include a dc offset, it is possible to make a correct adjustment of the tracking.
Inventors
- 👤 Shinichi Nagahara
- 👤 Naoharu Yanagawa
- 👤 Takaaki Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:15
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/094; G11B7/0901
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
98 words
A photo-detecting device comprising: a light receiving element which receives light reflected from an information recorded disc, said light receiving element having its light receiving surface divided into four sections A, B, C, D in the direction of tracking ; and a circuit to perform an operation of {(A+B)-(C+D)}-α{(A-B)+(C-D)} to calculate a correct tracking error not including a dc offset, wherein A, B, C and D are the quantities of light received at the corresponding light receiving sections, and α is a dc offset correcting constant for correcting the dc offset value peculiar to said light receiving element.
Claim 2
Dependent Claim
98 words
A photo-detecting device comprising: a light receiving element which receives light reflected from an information recorded disc, said light receiving element having its light receiving surface divided into four sections A, B, C, D in the direction of tracking ; and a circuit to perform an operation of {(A+B)-(C+D)}-α{(A-B)+(C-D)} to calculate a correct tracking error not including a dc offset, wherein A, B, C and D are the quantities of light received at the corresponding light receiving sections, and α is a dc offset correcting constant for correcting the dc offset value peculiar to said light receiving element.
Claim 3
Dependent Claim
41 words
A photo-detecting device as claimed in claim 1, wherein said dc offset correcting constant α is realized as a variable resistance which is preadjusted during the process of manufacture thereof in said circuit so as to provide an adequate value thereto.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-12-15 | 1996-06-15 | 1996-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-15 | 2000-06-15 | 2000-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-15 | 2004-06-15 | 2004-12-15 | $7700.00 | Window Closed / Lapsed |