US4326282A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for reproducing digitally coded information recorded on an optically readable disc-shaped record carrier
Assignee: US Philips Corp
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Filing: 1980-03-24
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Granted: 1982-04-20
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Expires: 2000-03-24
Abstract
Abstract Disclosed is an apparatus for reproducing digitally coded information recorded on a disc-shaped record carrier in the form of optically detectable, unit information areas arranged in accordance with a concentric or spiral track pattern. The apparatus comprises a filter which is tuned to a frequency f=V/L, V being the nominal tangential speed of the record carrier and L the nominal center-to-center distance of said unit areas. This frequency component has a frequency equal to twice the bit frequency of the coded information and is situated at a zero point of the power spectrum of said information, so that the extracted signal may be employed for the generation of a clock signal.
Inventors
- 👤 Johannes J. Verboom
- 👤 Marino G. Carasso
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:13
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/14; G11B20/1403; G11B20/1423; G11B20/1407; G11B20/1419; G11B7/00; G11B7/004; G11B7/005
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
164 words
An apparatus for reproducing a digitally coded signal recorded on a disc-shaped record carrier in the form of optically detectable, unit information areas arranged in a concentric or spiral track pattern, said apparatus comprising means for producing a light beam, an optical system for protecting the light beam onto the track pattern, a detector for detecting the presence of a unit area in said beam, a read circuit for reproducing the recorded digitally coded signal, and a clock-signal generation device for synchronizing the read circuit, said clock-signal generation device including a band-pass filter, having a center frequency which is substantially equal to twice the bit frequency of the recorded signal, for filtering the signal detected by the detector in order to obtain a clock signal, said bit frequency f complying with f=V/2L, where V is the nominal tangential speed of the record carrier at the location of reading and L the nominal minimum center-to-center distance of the unit areas at the location of reading.
Claim 2
Independent Claim
164 words
An apparatus for reproducing a digitally coded signal recorded on a disc-shaped record carrier in the form of optically detectable, unit information areas arranged in a concentric or spiral track pattern, said apparatus comprising means for producing a light beam, an optical system for protecting the light beam onto the track pattern, a detector for detecting the presence of a unit area in said beam, a read circuit for reproducing the recorded digitally coded signal, and a clock-signal generation device for synchronizing the read circuit, said clock-signal generation device including a band-pass filter, having a center frequency which is substantially equal to twice the bit frequency of the recorded signal, for filtering the signal detected by the detector in order to obtain a clock signal, said bit frequency f complying with f=V/2L, where V is the nominal tangential speed of the record carrier at the location of reading and L the nominal minimum center-to-center distance of the unit areas at the location of reading.
References Cited (Backward Citations)
US3501586A
Cited
US4238843A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-04-19 | 1985-10-19 | 1986-04-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-04-19 | 1989-10-19 | 1990-04-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-04-19 | 1993-10-19 | 1994-04-20 | $7700.00 | Window Closed / Lapsed |