US3876827A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for reading a disc-shaped record carrier
Assignee: US Philips Corp
•
Filing: 1973-10-29
•
Granted: 1975-04-08
•
Expires: 1993-10-29
Abstract
Abstract The invention relates to a device for reading a disc-shaped record carrier on which information is stored in tangentially arranged tracks. In order to keep the scanning point in track, a radial tracking system is provided. Moreover, in order to eliminate the effect of an out-of-roundness or eccentricity of the record carrier on the time base of the detected signal, a tangential tracking system is provided, which can cause a movement of the scanning point in the tangential direction. The control signal for said tangential tracking system is derived from the control signal for the radial tracking system with the aid of a phase-shifting element which causes a phase shift which corresponds to one fourth of a revolution period of the record carrier.
Inventors
- 👤 Peter Johannes Michiel Janssen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:26
CPC Classifications
G; G05; G05D; G05D3/00; G05D3/12; G05D3/14; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0901; G11B7/095; G11B7/0953
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
158 words
Apparatus for reading a rotating disc-shaped record carrier on which signals are stored in tangentially arranged tracks, comprising read unit means for scanning the tracks of the record carrier, first signal controlled means for radially moving the scanning of the read unit means with respect to the record carrier, second signal controlled means for tangentially moving the scanning of the read unit means with respect to the record carrier, a measuring detector for measuring the radial position of the read unit scan relative to a desired scanning point on the tracks of the record carrier and for providing a first control signal corresponding to said relative position, means connecting said first control signal to said first signal controlled means, and phase shift means connected to said second signal controlled means and providing a phase shift equal to one fourth of one revolution period of the record carrier for deriving a second control signal from the first control signal.
Claim 2
Dependent Claim
158 words
Apparatus for reading a rotating disc-shaped record carrier on which signals are stored in tangentially arranged tracks, comprising read unit means for scanning the tracks of the record carrier, first signal controlled means for radially moving the scanning of the read unit means with respect to the record carrier, second signal controlled means for tangentially moving the scanning of the read unit means with respect to the record carrier, a measuring detector for measuring the radial position of the read unit scan relative to a desired scanning point on the tracks of the record carrier and for providing a first control signal corresponding to said relative position, means connecting said first control signal to said first signal controlled means, and phase shift means connected to said second signal controlled means and providing a phase shift equal to one fourth of one revolution period of the record carrier for deriving a second control signal from the first control signal.
Claim 3
Dependent Claim
16 words
A device as claimed in claim 1, wherein said phase shift means comprises an integrating circuit.
Claim 4
Dependent Claim
36 words
A device as claimed in claim 1, wherein said phase shift means comprises a tachometer connected to said first signal controlled means for providing a signal proportional to the radial speed of the read unit means.
Claim 5
Dependent Claim
94 words
A device as claimed in claim 3, further comprising a second tachometer connected to said second signal controlled means for providing a signal proportional to the tangential motion of the read unit means, wherein said phase shift means is connected to the output of at least one of said two tachometers, a comparator connected to the output of said phase shift means and to the output of the tachometer not connected to the phase shift means, and means connecting the output of the comparator to the second signal controlled means as a control signal.
References Cited (Backward Citations)
US3381086A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |