US3906152A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for reading a disc-shaped record carrier
Assignee: US Philips Corp
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Filing: 1974-05-03
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Granted: 1975-09-16
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Expires: 1994-05-03
Abstract
Abstract An apparatus for reading a disc-shaped record carrier on which a video signal is recorded in optically coded form. To compensate for the varying frequency response of the record carrier as a function of the radial scanning position a correction device is provided. Said correction device employs the amplitude of a first carrier which is modulated with the luminance information of the video signal as a measuring signal, which is compared with a reference signal, the resultent signal controlling a correction filter. As reference signal the amplitude of a signal component of a relatively low frequency may be used, for example a pilot signal or a second carrier which is frequency-modulated with sound information.
Inventors
- 👤 Adrianus Huibert Hoogendijk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:44
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/76; H04N5/91; H04N5/93; H04N5/931; H04N5/9315; H04N9/00; H04N9/79; H04N9/793; H04N9/7933
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
204 words
An apparatus for reading a disc-shaped record carrier in which a video signal is recorded in an optically coded form, which signal comprises a first carrier signal component which is frequency-modulated with the luminance information, the apparatus including a correction device for automatically correcting variations in the frequency response of the record carrier as a result of a change of the radial scanning position on the record carrier, said correction device including a correction filter having an input means for receiving at least the detected first carrier signal component, a control input means for varying the frequency response of said correction filter, and an output; a first filter means for extracting the first signal component, a first detection circuit means coupled to said first filter for detecting the amplitude of said first signal component, an integration filter coupled to the output of said detection circuit and which has a relative large time constant, and a comparator circuit means for comparing the output signal of the integration filter with a reference signal and having an output means for supplying a control signal to said control input of the correction filter in response to the difference measured between the two input signals of said comparator circuit.
Claim 2
Independent Claim
204 words
An apparatus for reading a disc-shaped record carrier in which a video signal is recorded in an optically coded form, which signal comprises a first carrier signal component which is frequency-modulated with the luminance information, the apparatus including a correction device for automatically correcting variations in the frequency response of the record carrier as a result of a change of the radial scanning position on the record carrier, said correction device including a correction filter having an input means for receiving at least the detected first carrier signal component, a control input means for varying the frequency response of said correction filter, and an output; a first filter means for extracting the first signal component, a first detection circuit means coupled to said first filter for detecting the amplitude of said first signal component, an integration filter coupled to the output of said detection circuit and which has a relative large time constant, and a comparator circuit means for comparing the output signal of the integration filter with a reference signal and having an output means for supplying a control signal to said control input of the correction filter in response to the difference measured between the two input signals of said comparator circuit.
Claim 3
Dependent Claim
94 words
An apparatus as claimed in claim 1, wherein a second signal component is contained in the recorded video signal and which has a fixed amplitude and a comparatively low frequency relative to the first signal component, the correction device further comprising a second filter means for extracting said second signal component from the detected video signal and a second detection circuit means coupled to said second filter and to said comparator for detecting the amplitude of said second signal component and for applying the detected second signal to the comparator circuit as reference signal.
Claim 4
Dependent Claim
23 words
An apparatus as claimed in claim 2, wherein the second signal component comprises a pilot signal which is included in the video signal.
Claim 5
Dependent Claim
22 words
An apparatus as claimed in claim 2, wherein the second signal component comprises a frequency-modulated second carrier included in the video signal.
Claim 6
Dependent Claim
21 words
An apparatus as claimed in claim 4, wherein the modulated second carrier comprises the second information associated with the video signal.
Claim 7
Dependent Claim
20 words
An apparatus as claimed in claim 1, wherein the first filter is coupled to the output of the correction filter.
Claim 8
Dependent Claim
19 words
An apparatus as claimed in claim 1, wherein said correction filter input means receives all of the recorded signal.
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) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |