US3688031A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Horizontal oscillator disabling
Assignee: RCA Licensing Corp
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Filing: 1971-05-18
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Granted: 1972-08-29
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Expires: 1991-05-18
Abstract
Abstract Pending U.S. Pat. Applications Ser. Nos. 103,713 and 121,250 disclose high voltage protection circuits which change the frequency of the horizontal oscillator of a television receiver in response to an indication of increase in the ultor potential developed for its picture tube which could cause danger of Xradiation. Whereas the circuits of such disclosures operate to change a voltage in the horizontal oscillator to which a capacitor is required to charge in establishing the oscillator frequency, the circuit of the instant invention operates to vary a resistance which, together with a capacitor of this type, sets the time constant which determines such frequency.
Inventors
- 👤 William Vincent Fitzgerald Jr
- 👤 Paul Carleton Wilmarth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:28
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/20
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
251 words
In a television receiver having an image display device, a deflection circuit including an oscillation signal generator, and a high voltage circuit responsive to the generation of such oscillation signals to develop the high voltage needed to operate said display device, and wherein a resistance-capacitance time constant network is also included to set the frequency at which such oscillation signals are generated, the combination therewith of: means coupled to said deflection output circuit for developing a control signal representative of the high voltage developed and of a first magnitude and polarity when said high voltage is within a prescribed range of operation and of a second magnitude and polarity when said high voltage is in excess of said operating range; variable impedance means cooperatively coupled to said time constant network to adjust said oscillation frequency as may be desired; and means applying said developed control signals to said variable impedance means, said impedance means cooperating with the resistance component of said time constant network to have substantially little effect on the initially established oscillation frequency in response to the application of said control signal of first magnitude and polarity, but to substantially change said initial frequency in response to the application of said control signal of second magnitude and polarity; with said change of frequency of said oscillation generator being in a direction to render the image reproduction of said display device unviewable and to thereby provide a protective alert as to the existence of high voltage problems within said receiver.
Claim 2
Dependent Claim
251 words
In a television receiver having an image display device, a deflection circuit including an oscillation signal generator, and a high voltage circuit responsive to the generation of such oscillation signals to develop the high voltage needed to operate said display device, and wherein a resistance-capacitance time constant network is also included to set the frequency at which such oscillation signals are generated, the combination therewith of: means coupled to said deflection output circuit for developing a control signal representative of the high voltage developed and of a first magnitude and polarity when said high voltage is within a prescribed range of operation and of a second magnitude and polarity when said high voltage is in excess of said operating range; variable impedance means cooperatively coupled to said time constant network to adjust said oscillation frequency as may be desired; and means applying said developed control signals to said variable impedance means, said impedance means cooperating with the resistance component of said time constant network to have substantially little effect on the initially established oscillation frequency in response to the application of said control signal of first magnitude and polarity, but to substantially change said initial frequency in response to the application of said control signal of second magnitude and polarity; with said change of frequency of said oscillation generator being in a direction to render the image reproduction of said display device unviewable and to thereby provide a protective alert as to the existence of high voltage problems within said receiver.
Claim 3
Dependent Claim
70 words
The combination of claim 1 wherein said variable impedance means includes a transistor biased to a first state of conduction by said control signal of first magnitude and polarity, reflecting the development of high voltages within said prescribed operating range, but biased to a second state of conduction by said control signal of second magnitude and polarity, reflecting developed high voltages in excess of the upper limit of said range.
Claim 4
Dependent Claim
88 words
The combination of claim 2 wherein a relatively stable bias potential is also applied to said transistor for combination with said control signal developed by said first mentioned means, and of a magnitude and polarity to bias said transistor into saturation when combined with a control signal reflecting the development of high voltages within said range of operation and to bias said transistor to its non-conducting condition when combined with a control signal reflecting the development of high voltages in excess of the upper limit of said range.
Claim 5
Dependent Claim
88 words
The combination of claim 3 wherein said variable impedance means also includes a resistance device adjustable to alter the resistance component of said time constant network to initially establish the frequency of said oscillation signal generator, and coupled in series with the input and output electrodes of said transistor for automatically changing the resistance component of said network as said transistor is biased from a saturated condition to a conductive condition in response to the application of said control signal indicating the condition of excess high voltage development.
Claim 6
Dependent Claim
65 words
The combination of claim 4 for use in a television receiver including a transformer through which flyback voltage pulses flow in the development of the high voltage needed to operate said display device, and wherein said control signal developing means includes a rectifier capacitor network to monitor the magnitude of said voltage pulses and to develop a unidirectional potential signal representative of the magnitude thereof.
Claim 7
Dependent Claim
59 words
The combination of claim 5 wherein said source of relatively stable potential provides a subsTantially fixed positive direct potential to the base electrode of said transistor and wherein said control signal developing means provides a negative direct voltage thereto, the magnitude of which varies as a function of the amplitude of said flyback pulses reflecting the high voltage generation.
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) | 1975-08-29 | 1976-02-28 | 1976-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-29 | 1980-02-28 | 1980-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-29 | 1984-02-28 | 1984-08-29 | $7700.00 | Window Closed / Lapsed |