US3736370A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Improved chroma clamping circuit
Assignee: RCA Licensing Corp
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Filing: 1971-01-18
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Granted: 1973-05-29
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Expires: 1991-01-18
Abstract
Abstract A clamping circuit for use in a color television receiver. The DC voltage level of color signal transmission paths is reestablished during horizontal retrace periods by applying a clamping pulse derived from the horizontal output transformer directly to the transmission path. The maximum excursion of the voltage thus applied is limited by a diode reverse-biased by means of a reference voltage network, which includes a transistor resistively coupled between a voltage source and ground. The transistor passes a constant flow of current such that changes in the value of the voltage source are added to the reverse bias on the limiting diode. The maximum voltage of the clamping pulse is thus varied to reflect changes in the value of the voltage source.
Inventors
- 👤 R Thielking
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:27
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/72
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
179 words
In a color television receiver including a transmission path for transmitting a color signal to a first electrode of a cathode ray tube, means for supplying an unregulated biasing voltage to a second electrode of the cathode ray tube, said unregulated biasing voltage being susceptible of fluctuations, means for periodically establishing the transmission path at a predetermined voltage level, comprising: clamping circuit means for periodically applying a first voltage to the transmission path; first unidirectional conducting means having a first and a second side, said first side being coupled to said means for applying the first, clamping voltage; means for deriving a second, reference voltage which fluctuates in substantially the same amounts as said biasing voltage comprising the series combination of resistor means and variable impedance means for passing a substantially, constant current in the presence of varying voltages impressed thereacross; means for connecting said series combination across a source of unregulated biasing voltage; and means for coupling said second, reference voltage to said second side of said unidirectional conducting means to limit the value of said first voltage.
Claim 2
Dependent Claim
179 words
In a color television receiver including a transmission path for transmitting a color signal to a first electrode of a cathode ray tube, means for supplying an unregulated biasing voltage to a second electrode of the cathode ray tube, said unregulated biasing voltage being susceptible of fluctuations, means for periodically establishing the transmission path at a predetermined voltage level, comprising: clamping circuit means for periodically applying a first voltage to the transmission path; first unidirectional conducting means having a first and a second side, said first side being coupled to said means for applying the first, clamping voltage; means for deriving a second, reference voltage which fluctuates in substantially the same amounts as said biasing voltage comprising the series combination of resistor means and variable impedance means for passing a substantially, constant current in the presence of varying voltages impressed thereacross; means for connecting said series combination across a source of unregulated biasing voltage; and means for coupling said second, reference voltage to said second side of said unidirectional conducting means to limit the value of said first voltage.
Claim 3
Dependent Claim
153 words
In a color television receiver including means for producing periodic voltage pulses, a cathode ray tube, a transmission path for transmitting a color signal to a first electrode of the cathode ray tube, and means for applying an unregulated biasing voltage susceptible of variations to a second electrode of the cathode ray tube: circuit means for applying periodic voltage pulses to the transmission path; means for transmitting periodic voltage pulses to said circuit means; variable impedance means for passing a substantially constant current in the presence of varying voltages impressed thereacross; first resistive means coupled in series with said variable impedance means, the series circuit so comprised being coupled between a point of biasing potential and a point of reference potential; and second circuit means coupling the junction of said circuit means and said means for transmitting periodic voltage pulses, and the junction between said variable impedance means and said first resistive means.
Claim 4
Dependent Claim
153 words
In a color television receiver including means for producing periodic voltage pulses, a cathode ray tube, a transmission path for transmitting a color signal to a first electrode of the cathode ray tube, and means for applying an unregulated biasing voltage susceptible of variations to a second electrode of the cathode ray tube: circuit means for applying periodic voltage pulses to the transmission path; means for transmitting periodic voltage pulses to said circuit means; variable impedance means for passing a substantially constant current in the presence of varying voltages impressed thereacross; first resistive means coupled in series with said variable impedance means, the series circuit so comprised being coupled between a point of biasing potential and a point of reference potential; and second circuit means coupling the junction of said circuit means and said means for transmitting periodic voltage pulses, and the junction between said variable impedance means and said first resistive means.
Claim 5
Dependent Claim
163 words
In a color television receiver including a transmission path for transmitting a color signal to a first electrode of a cathode ray tube, means for applying an unregulated biasing voltage to a second electrode of the cathode ray tube and, means for periodically establishing the transmission path at a predetermined voltage level with respect to said second electrode, comprising: first circuit means for periodically applying a clamping voltage to the transmission path; and variable impedance means for passinG a substantially constant current over a range of voltages thereacross; first resistive means coupled to said variable impedance means; means for coupling the series combination of said variable impedance means and said first resistive means between a point of unregulated potential and a point of reference potential; and second circuit means coupling the intersection of said first resistive means and said variable impedance means to said first circuit means; whereby the maximum excursion of the clamping voltage is caused to vary with the biasing voltage.
Claim 6
Dependent Claim
163 words
In a color television receiver including a transmission path for transmitting a color signal to a first electrode of a cathode ray tube, means for applying an unregulated biasing voltage to a second electrode of the cathode ray tube and, means for periodically establishing the transmission path at a predetermined voltage level with respect to said second electrode, comprising: first circuit means for periodically applying a clamping voltage to the transmission path; and variable impedance means for passinG a substantially constant current over a range of voltages thereacross; first resistive means coupled to said variable impedance means; means for coupling the series combination of said variable impedance means and said first resistive means between a point of unregulated potential and a point of reference potential; and second circuit means coupling the intersection of said first resistive means and said variable impedance means to said first circuit means; whereby the maximum excursion of the clamping voltage is caused to vary with the biasing voltage.
Claim 7
Dependent Claim
16 words
The invention as defined in claim 3, wherein said second circuit means comprises unidirectional conductive means.
Claim 8
Dependent Claim
161 words
In a color television receiver including a transmission path for transmitting a color signal to an electrode of a cathode ray tube, means for periodically establishing the transmission path at a predetermined voltage level, comprising: first unidirectional conducting means having a first and a second side, said second side being coupled to the transmission path; clamping circuit means for applying a first, clamping voltage to said first side of said first unidirectional conducting means; second unidirectional conducting means having a first and a second side, said first side being coupled to said means for applying said first clamping voltage; and means for deriving a second, reference voltage comprising variable impedance means for passing a substantially constant current over a range of voltages impressed thereacross, first resistive means for coupling said variable impedance means to a source of biasing voltage, and means for applying the voltage impressed across said variable impedance means to said second side of said second unidirectional conducting means.
Claim 9
Dependent Claim
161 words
In a color television receiver including a transmission path for transmitting a color signal to an electrode of a cathode ray tube, means for periodically establishing the transmission path at a predetermined voltage level, comprising: first unidirectional conducting means having a first and a second side, said second side being coupled to the transmission path; clamping circuit means for applying a first, clamping voltage to said first side of said first unidirectional conducting means; second unidirectional conducting means having a first and a second side, said first side being coupled to said means for applying said first clamping voltage; and means for deriving a second, reference voltage comprising variable impedance means for passing a substantially constant current over a range of voltages impressed thereacross, first resistive means for coupling said variable impedance means to a source of biasing voltage, and means for applying the voltage impressed across said variable impedance means to said second side of said second unidirectional conducting means.
Claim 10
Dependent Claim
18 words
The invention as defined in claim 5 wherein said first and said second unidirectional conducting means are diodes.
Claim 11
Dependent Claim
48 words
The invention as defined in claim 6, wherein said means for applying a first, clamping voltage comprises the series combination of second resistive means and capacitor means adapted to be coupled between the first side of said first unidirectional conducting means and a source of periodic voltage pulses.
Claim 12
Dependent Claim
34 words
The invention as defined in claim 7, further including third resistive means connected in shunt with said first unidirectional conducting means, and fourth resistive means connected in shunt with said second unidirectional conducting means.
Claim 13
Dependent Claim
23 words
The invention as defined in claim 8, wherein said variable impedance means comprises the series combination of transistor means and fifth resistive means.
Claim 14
Dependent Claim
28 words
The invention as defined in claim 9, wherein said means for applying a second, reference voltage further includes sixth resistive means connected in parallel with said transistor 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) | 1976-05-28 | 1976-11-27 | 1977-05-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-28 | 1980-11-27 | 1981-05-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-28 | 1984-11-27 | 1985-05-29 | $7700.00 | Window Closed / Lapsed |