US3560650A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control circuit
Assignee: Zenith Electronics LLC
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Filing: 1968-12-20
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Granted: 1971-02-02
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Expires: 1988-12-20
Abstract
Abstract A control circuit for preventing the application of accelerating potential in excess of a predetermined maximum value to the cathode-ray picture tube of a television receiver. Positive polarity pulses amplitude-related to the applied accelerating potential are derived from the receiver horizontal deflection system and impressed across the collector-base junction of a transistor. This junction functions as a diode, and in cooperation with an external base-circuit capacitorpeak-rectifies the pulses to develop on the transistor''s base a pulse-amplitude dependent control voltage. The emitter of the transistor is connected to the control electrode of a silicon controlled rectifier, which has principal electrodes connected between the screen of the horizontal deflection system output tube and ground. When the control voltage developed on the base exceeds the breakdown voltage of the transistor''s emitter-base junction, the control voltage is impressed on the control electrode of the silicon controlled rectifier and causes that device to conduct, substantially reducing the screen current applied to the output tube. This reduces the energy available for powering the receiver''s sweep-excited high voltage power supply, and hence prevents further generation of accelerating potential in excess of the predetermined maximum value.
Inventors
- 👤 Judson A Hofmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:36
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/20
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
141 words
In a television receiver of the type including an image reproducer requiring an externally applied high-voltage accelerating potential, and a high-voltage power supply comprising a high-voltage pulse transformer and a high-voltage rectifier for supplying said potential, a control circuit for preventing said accelerating potential from exceeding a predetermined maximum value comprising: low voltage control means actuable by an externally applied voltage to regulate or interrupt said power supply; means comprising an auxiliary winding of said pulse transformer constituting a source of pulses amplitude-related to said accelerating potential; means for rectifying said pulses to produce a control voltage representative of the amplitude of said pulses; and threshold means for applying said control voltage to said control means to regulate or interrupt said power supply only when said control voltage exceeds a threshold value corresponding to said predetermined maximum value of accelerating potential.
Claim 2
Dependent Claim
141 words
In a television receiver of the type including an image reproducer requiring an externally applied high-voltage accelerating potential, and a high-voltage power supply comprising a high-voltage pulse transformer and a high-voltage rectifier for supplying said potential, a control circuit for preventing said accelerating potential from exceeding a predetermined maximum value comprising: low voltage control means actuable by an externally applied voltage to regulate or interrupt said power supply; means comprising an auxiliary winding of said pulse transformer constituting a source of pulses amplitude-related to said accelerating potential; means for rectifying said pulses to produce a control voltage representative of the amplitude of said pulses; and threshold means for applying said control voltage to said control means to regulate or interrupt said power supply only when said control voltage exceeds a threshold value corresponding to said predetermined maximum value of accelerating potential.
Claim 3
Dependent Claim
44 words
A control circuit as described in claim 1 including a capacitor, and a transistor having base, emitter and collector electrodes and collector-base and emitter-base junctions, wherein said rectifying means comprises said collector-base junction and said capacitor, and said threshold means comprises said emitter-base junction.
Claim 4
Dependent Claim
39 words
A control circuit as described in claim 2 wherein said collector electrode is coupled to said source of pulses, said base electrode is coupled to ground by said capacitor, and said emitter electrode is coupled to said control means.
Claim 5
Dependent Claim
37 words
A control circuit as described in claim 3 Wherein said control means comprises a silicon controlled rectifier having a pair of principal electrodes and a control electrode, and said emitter electrode is coupled to said control electrode.
Claim 6
Dependent Claim
48 words
A control circuit as described in claim 4 wherein said receiver further includes a reaction-scanning system having a flyback transformer, wherein said high-voltage power supply is coupled to said system and derives operating power therefrom, and wherein said source of pulses comprises a winding on said flyback transformer.
Claim 7
Dependent Claim
33 words
A control circuit as described in claim 5 wherein said control means is coupled to said reaction-scanning system and interrupts or regulates said power supply by at least partially disabling said scanning system.
Claim 8
Dependent Claim
28 words
A control circuit as described in claim 6 wherein said scanning system includes an electron-discharge device and said control means functions by at least partially disabling said device.
Claim 9
Dependent Claim
49 words
A control circuit as described in claim 7 wherein said electron-discharge device has a screen grid requiring a an externally applied unidirectional current, and said silicon controlled rectifier is coupled between said screen grid and ground to at least partially interrupt the application of current to said screen grid.
Claim 10
Dependent Claim
129 words
An overvoltage detector for monitoring a high-voltage power supply to provide an indication when the output voltage of said power supply has an amplitude in excess of a predetermined maximum value, comprising: a transistor having base, emitter and collector electrodes and collector-base and emitter-base junctions; a capacitor coupled between said base electrode and ground; means for applying said signal to said collector-base junction to develop at said base electrode a control voltage representative of the amplitude of said signal; utilization means responsive to an applied control effect to change its operating condition and provide an indication of such change; and threshold means comprising said emitter-base junction for applying said control voltage to said utilization means only when said control voltage exceeds a level corresponding to said predetermined maximum value.
Claim 11
Dependent Claim
129 words
An overvoltage detector for monitoring a high-voltage power supply to provide an indication when the output voltage of said power supply has an amplitude in excess of a predetermined maximum value, comprising: a transistor having base, emitter and collector electrodes and collector-base and emitter-base junctions; a capacitor coupled between said base electrode and ground; means for applying said signal to said collector-base junction to develop at said base electrode a control voltage representative of the amplitude of said signal; utilization means responsive to an applied control effect to change its operating condition and provide an indication of such change; and threshold means comprising said emitter-base junction for applying said control voltage to said utilization means only when said control voltage exceeds a level corresponding to said predetermined maximum value.
References Cited (Backward Citations)
US3427496A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |