Patent US4775968A successfully refreshed from Google Patents.
US4775968A
Expired / Lapsed
US
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Tracking error detecting system for optical head
Assignee: Sony Corp
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Filing: 1985-10-03
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Granted: 1988-10-04
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Expires: 2005-10-03
Abstract
Abstract According to a tracking error system of an optical head of the present invention, a pair of beams are irradiated through an objective lens (4) on an optical record medium (5) with a distance of a multiple of an odd number of substantially 1/2 the track pitch thereof, a pair of beams emitted from the optical record medium (5) are respectively introduced into a pair of two-divided photo detection elements (6 1 ) and (6 2 ) and a tracking error signal is obtained from a difference between difference outputs between outputs of both detected outputs from the pair of respective two-divided photo detection elements (6 1 ) and (6 2 ). Thus, it is possible to remove a DC fluctuation of a tracking error signal caused by the lateral movement of the objective lens (4) and a radial skew of the optical record medium (5).
Inventors
- 👤 Kiyoshi Ohsato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:52
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0901; G11B7/0903; G11B7/0943; G11B7/095; G11B7/0956
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
169 words
In an optical storage device having means for reading or writing information on plural adjacent tracks on an optical record medium, and means for tracking a path along one of said tracks, a tracking error detection system comprising, in combination, means for forming a pair of beams and focusing said beams through an objective lens onto said optical record medium with a distance equal to an odd multiple of substantially one half of the distance between adjacent tracks, first and second pairs of side-by-side photo detection elements, means for conducting a pair of beams emitted from said optical record medium onto said photo detection elements, means for deriving a first difference signal in response to signals from said first pair of photo detection elements, means for deriving a second difference signal in response to signals from said second pair of photo detection elements, and means connected to both of said deriving means for generating a tracking error in response to the difference between said first and second difference signals.
Claim 2
Dependent Claim
169 words
In an optical storage device having means for reading or writing information on plural adjacent tracks on an optical record medium, and means for tracking a path along one of said tracks, a tracking error detection system comprising, in combination, means for forming a pair of beams and focusing said beams through an objective lens onto said optical record medium with a distance equal to an odd multiple of substantially one half of the distance between adjacent tracks, first and second pairs of side-by-side photo detection elements, means for conducting a pair of beams emitted from said optical record medium onto said photo detection elements, means for deriving a first difference signal in response to signals from said first pair of photo detection elements, means for deriving a second difference signal in response to signals from said second pair of photo detection elements, and means connected to both of said deriving means for generating a tracking error in response to the difference between said first and second difference signals.
Claim 3
Dependent Claim
21 words
A tracking error detection system according to claim 1, both pairs of photo detection elements are formed on the same plane.
Claim 4
Dependent Claim
43 words
A tracking error detection system according to claim 4, wherein said beam forming means comprises a single semiconductor laser element, and a diffraction grating positioned relative to said laser element to transmit a beam from said laser element to form said two beams.
References Cited (Backward Citations)
US4037252A
Cited
US4065786A
Cited
JPS52145006A
Cited
JPS58185045A
Cited
JPS58208939A
Cited
JPS5914148A
Cited
JPS5958638A
Cited
JPS59172171A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-04 | 1992-04-04 | 1992-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-04 | 1996-04-04 | 1996-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-04 | 2000-04-04 | 2000-10-04 | $7700.00 | Window Closed / Lapsed |