Patent US4922118A successfully refreshed from Google Patents.
US4922118A
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Apparatus for increasing number of scanning lines
Assignee: Mitsubishi Electric Corp
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Filing: 1989-05-18
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Granted: 1990-05-01
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Expires: 2009-05-18
Abstract
Abstract The present invention relates to a scanning line converter which converts the number of scanning lines into a multiple thereof. Write-clock-pulses and read-clock-pulses for controlling read/write accesses to a video memory, are produced on a basis of signals obtained by differentiating both a horizontal synchronizing signal and a double-speed horizontal synchronizing signal with respect to stable master clock pulses. The double-speed horizontal synchronizing signal is stabilized by a method, wherein double-speed horizontal oscillation pulses with a multiple frequency of the horizontal synchronizing signal, are delayed and further converted to a saw-tooth-wave signal, and the phase errors between the saw-tooth-wave signal and the horizontal synchronizing signal are fed back to the double-speed horizontal pulse oscillator.
Inventors
- 👤 Kazuya Maeshima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:04
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/04; H04N5/12; H04N5/126
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
138 words
An apparatus for increasing a number of scanning lines, comprising: a video memory for reading/writing a video signal of a television signal, a double-speed horizontal synchronizing signal producing circuit for producing a double-speed horizontal synchronizing signal from a horizontal synchronizing signal extracted from said television signal, a master clock oscillator for generating master clock pulses as a reference signal independent of both the horizontal synchronizing signal and the double-speed horizontal synchronizing signal, a first differentiating circuit and a second differentiating circuit for differentiating said horizintal synchronizing signal and said double-speed horizontal synchronizing signal, respectively, with respect to said master clock pulses, a frequency demultiplying counter and a double-speed frequency demultiplying counter being preset with respective differentiating pulses obtained from said first and second differentiating circuit, for outputting write-clock-pulses and read-clock-pulses, respectively, in synchronism with said master clock pulses.
Claim 2
Independent Claim
138 words
An apparatus for increasing a number of scanning lines, comprising: a video memory for reading/writing a video signal of a television signal, a double-speed horizontal synchronizing signal producing circuit for producing a double-speed horizontal synchronizing signal from a horizontal synchronizing signal extracted from said television signal, a master clock oscillator for generating master clock pulses as a reference signal independent of both the horizontal synchronizing signal and the double-speed horizontal synchronizing signal, a first differentiating circuit and a second differentiating circuit for differentiating said horizintal synchronizing signal and said double-speed horizontal synchronizing signal, respectively, with respect to said master clock pulses, a frequency demultiplying counter and a double-speed frequency demultiplying counter being preset with respective differentiating pulses obtained from said first and second differentiating circuit, for outputting write-clock-pulses and read-clock-pulses, respectively, in synchronism with said master clock pulses.
Claim 3
Dependent Claim
27 words
An apparatus according to claim 1, wherein a master clock frequency of said master clock oscillator is higher than the frequency of said double-speed horizontal synchronizing signal.
Claim 4
Dependent Claim
21 words
An apparatus according to claim 2, wherein said double-speed horizontal synchronizing signal producing circuit is of an automatic frequency control circuit.
Claim 5
Dependent Claim
107 words
An apparatus according to claim 3, wherein said automatic frequency control circuit comprises; a double-speed horizontal oscillator for generating double-speed horizontal oscillation pulses having a frequency which is double the frequency of the horizontal synchronizing signal, a synchronizing signal producing circuit for delaying said double-speed horizontal oscillation pulses, a saw-tooth-wave forming circuit for converting an output signal of the synchronizing signal producing circuit into a saw-tooth-wave signal, a phase discriminating circuit for performing phase discrimination between said saw-tooth-wave signal and the horizontal synchronizing signal, an integrating circuit for smoothing an output signal of the phase discriminating circuit to output a smoothed signal to said double-speed horizontal oscillator.
Claim 6
Dependent Claim
38 words
An apparatus according to claim 4, wherein said phase discriminating circuit detects phase displacement at a rising portion of said saw-tooth-wave signal taking said horizontal synchronizing signal as a time reference, and outputs a result of the detection.
Claim 7
Dependent Claim
25 words
An apparatus according to claim 5, wherein said double speed horizontal synchronizing signal is output from the output terminal of said synchronizing signal producing circuit.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-30 | 1993-10-30 | 1994-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-30 | 1997-10-30 | 1998-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-30 | 2001-10-30 | 2002-05-01 | $7700.00 | Window Closed / Lapsed |