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Patent US3694567A successfully refreshed from Google Patents.
US3694567A
Expired / Lapsed
US
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Constant amplitude phase shifter
Assignee: Magnovox Co
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Filing: 1970-05-11
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Granted: 1972-09-26
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Expires: 1990-05-11
Abstract
Abstract In many color television circuitry designs, a 3.58 mHz reference signal is provided to the automatic phase control phase detector and the color killer phase detector, and in a closed loop color synchronization circuit, the reference signal to the color killer detector is shifted in phase 90* relative to the automatic phase control detector. In addition, harmonics of the reference signal and color burst signal must be controlled. Further, in many circuits an adjustable phase section is added to adjust the phase of the reference signal to the automatic phase control detector and the color killer detector for tint control. This invention provides circuitry which will bypass the harmonics to ground and compensate for the impedances of such harmonic bypass circuit and the color killer detector fixed phase shifter and provides a substantially constant amplitude to the phase detectors for all positions of the adjustable phase shift circuit. In a preferred embodiment, an equivalent resistance is uniquely determined and the impedance of a harmon bypass circuit and the fixed phase shift device of the color killer detector is made substantially equal to this equivalent resistance to provide the constant amplitude signal to the detectors.
Inventors
- 👤 John M Kresock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:25
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/643
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
99 words
Apparatus comprising input means, output means, constant phase shift means, said constant phase shift means being between said input means and output means to provide a fixed adjustment of the phase of a signal therebetween, shunt means for shunting away predetermined unwanted signals from both said Input means and output means, variable phase shift means for providing a variable adjustment of the phase between said input and output means, the sum of the admittances of said constant phase shift means, said shunt means and said variable phase shift means being substantially equal at a plurality of phase shift positions.
Claim 2
Dependent Claim
99 words
Apparatus comprising input means, output means, constant phase shift means, said constant phase shift means being between said input means and output means to provide a fixed adjustment of the phase of a signal therebetween, shunt means for shunting away predetermined unwanted signals from both said Input means and output means, variable phase shift means for providing a variable adjustment of the phase between said input and output means, the sum of the admittances of said constant phase shift means, said shunt means and said variable phase shift means being substantially equal at a plurality of phase shift positions.
Claim 3
Dependent Claim
113 words
Constant amplitude phase shift circuit comprising input means for providing a fundamental signal, output means comprising a first and second output for receiving the fundamental signal, constant phase shift means including inductance, capacitance, and resistance means for providing a constant phase shift of the fundamental to said second output, bypass means for bypassing to ground harmonics from both said input means and output means, variable phase shift means for providing a variable adjustment of the phase between said input and output means, the sum of the admittances of said constant phase shift means, said harmonic bypass means and said variable phase shift means being substantially equal at a plurality of phase shift positions.
Claim 4
Dependent Claim
113 words
Constant amplitude phase shift circuit comprising input means for providing a fundamental signal, output means comprising a first and second output for receiving the fundamental signal, constant phase shift means including inductance, capacitance, and resistance means for providing a constant phase shift of the fundamental to said second output, bypass means for bypassing to ground harmonics from both said input means and output means, variable phase shift means for providing a variable adjustment of the phase between said input and output means, the sum of the admittances of said constant phase shift means, said harmonic bypass means and said variable phase shift means being substantially equal at a plurality of phase shift positions.
Claim 5
Dependent Claim
198 words
Constant amplitude phase shift circuit comprising automatic phase control phase detector, color killer phase detector, CW oscillator for providing a reference signal to said automatic phase control phase detector and the color killer phase detector, phase shift means comprising means for shifting the phase of the reference signal to the color killer phase detector substantially 90* from the phase provided to the automatic phase control phase detector, capacitor means for bypassing to ground harmonics from both of said phase detectors and from said CW oscillator, variable phase shift means for variably shifting the phase of the reference signal to both of said phase detectors, the admittance of the equivalent resistance of said phase shift means plus said capacitor means being substantially equal to that admittance required to be added to the admittance of the variable phase shift circuit to provide a substantially constant amplitude admittance for the combination of said phase shift means, variable phase shift means and capacitor means over the phase shift range of said variable phase shifter to provide a substantially constant amplitude signal to said automatic phase control and color killer phase detectors over the range of phase shift of said phase shift means.
Claim 6
Dependent Claim
198 words
Constant amplitude phase shift circuit comprising automatic phase control phase detector, color killer phase detector, CW oscillator for providing a reference signal to said automatic phase control phase detector and the color killer phase detector, phase shift means comprising means for shifting the phase of the reference signal to the color killer phase detector substantially 90* from the phase provided to the automatic phase control phase detector, capacitor means for bypassing to ground harmonics from both of said phase detectors and from said CW oscillator, variable phase shift means for variably shifting the phase of the reference signal to both of said phase detectors, the admittance of the equivalent resistance of said phase shift means plus said capacitor means being substantially equal to that admittance required to be added to the admittance of the variable phase shift circuit to provide a substantially constant amplitude admittance for the combination of said phase shift means, variable phase shift means and capacitor means over the phase shift range of said variable phase shifter to provide a substantially constant amplitude signal to said automatic phase control and color killer phase detectors over the range of phase shift of said phase shift means.
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) | 1975-09-26 | 1976-03-27 | 1976-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-26 | 1980-03-27 | 1980-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-26 | 1984-03-27 | 1984-09-26 | $7700.00 | Window Closed / Lapsed |