US3692933A
Expired / Lapsed
US
⏱️ 0.0 years remaining
X-radiation protection circuit
Assignee: Admiral Corp
•
Filing: 1970-10-28
•
Granted: 1972-09-19
•
Expires: 1990-10-28
Abstract
Abstract A protective circuit is disclosed which is adapted to detect and indicate an overvoltage condition in a television receiver by blanking both sound and picture information. The circuit is coupled between an output of the receiver''s high voltage transformer and an input of the receiver''s automatic gain control (AGC) system. The normal input signal to the AGC circuit is a video information component of a broadcast television signal selected by the tuner and amplified. The AGC system normally responds to the varying signal strength of the synchronizing signal information of the video signal to control the gain of the receiver''s tuner and IF amplifier sections. Should the output of the receiver''s high voltage transformer rise above a predetermined level, the protective circuit generates a failure signal which causes the AGC system to cut off signal flow through the tuner and IF sections, thus terminating both audio and video reproduction by the receiver.
Inventors
- 👤 Ronald S Knoll
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:43
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/22; H03G3/26; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/20
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
129 words
In a cathode ray tube image reproducing system including a high voltage supply wherein a broadcast television signal including a video signal component is translated through amplifier stages having controlled gain characteristics, the combination comprising: means for sampling an operating voltage output of said high voltage supply and for developing a monitoring signal proportional thereto, gain control means responsive to the strength of said video signal component for controlling the gain of said amplifier stages, and overvoltage protection means coupled to said gain control means and responsive to said sampling means for controlling said gain control means to limit the gain of said amplifier stages when said operating voltage exceeds a predetermined level thereby effectively preventing signal amplification by said amplifier stages and providing an indication of system malfunction.
Claim 2
Dependent Claim
129 words
In a cathode ray tube image reproducing system including a high voltage supply wherein a broadcast television signal including a video signal component is translated through amplifier stages having controlled gain characteristics, the combination comprising: means for sampling an operating voltage output of said high voltage supply and for developing a monitoring signal proportional thereto, gain control means responsive to the strength of said video signal component for controlling the gain of said amplifier stages, and overvoltage protection means coupled to said gain control means and responsive to said sampling means for controlling said gain control means to limit the gain of said amplifier stages when said operating voltage exceeds a predetermined level thereby effectively preventing signal amplification by said amplifier stages and providing an indication of system malfunction.
Claim 3
Dependent Claim
81 words
The device of claim 1 wherein said gain control means includes a controlled conductance element coupled to said overvoltage protection means having a first operating state when said operating voltage is less than said predetermined operating voltage level wherein the conductance of said element is determined by the strength of said signal and having a second operating state when said operating voltage exceeds said predetermined level wherein the conductance of said element is determined by the magnitude of the monitoring signal.
Claim 4
Dependent Claim
59 words
The device of claim 1 wherein said overvoltage protection means includes voltage breakdown means coupled between said sampling means and said gain control means, said voltage breakdown means being adapted to couple said monitoring signal to said gain control means upon being rendered conducting by said monitoring signal when the operating voltage of the system exceeds a predetermined level.
Claim 5
Dependent Claim
103 words
The device of claim 3 wherein said gain control means includes a vacuum tube having a grid, plate and cathode, the cathode being connected to a source of constant potential, the plate being connected to said amplifier stages and the grid being coupled to said video signal and connected through said voltage breakdown means to said sampling means so that the conductance of said vacuum tube is a function of the magnitude of said video signal for operating voltages less than said predetermined Level, the conductance being controlled by said monitoring signal when the operating voltage of the system exceeds a predetermined level.
Claim 6
Dependent Claim
41 words
The device of claim 3 wherein said voltage breakdown means is characterized by a substantially symmetrical volt-ampere characteristic in the region of the breakdown voltage and is adapted to restore normal operation of the receiver following a momentary high voltage surge.
Claim 7
Dependent Claim
39 words
The device of claim 1 wherein said overvoltage protection means includes switch means coupled to said gain control means for selectively applying said video signal and the monitoring signal output of said sampling means to said gain control means.
Claim 8
Dependent Claim
71 words
The device of claim 6 wherein said switch means includes a transistor having a first electrode coupled to said gain control means, a second electrode coupled to a source of constant potential and a control electrode coupled to said sampling means, said transistor being normally biased off and adapted to be biased on by the monitoring signal from said sampling means indicating an operating voltage in excess of said predetermined level.
Claim 9
Dependent Claim
94 words
The device of claim 7 wherein said gain control means includes a vacuum tube having a grid, plate and cathode, the cathode being coupled to said amplifier stages, said grid and plate being connected to the first and second electrodes of said transistor so that said vacuum tube has a first operating state wherein its conductance is controlled by the magnitude of said video signal and a second operating state when said operating voltage exceeds said predetermined level wherein the conductance of said vacuum tube is controlled by the magnitude of said monitoring signal.
Claim 10
Dependent Claim
38 words
The device of claim 7 wherein said overvoltage protection means includes voltage breakdown means coupled between said signal developing means and said control electrode and having a breakdown voltage adapted to establish said predetermined level of operating voltage.
Claim 11
Dependent Claim
41 words
The device of claim 9 wherein said voltage breakdown means is characterized by a substantially symmetrical volt-ampere characteristic in the region of the breakdown voltage and is adapted to restore normal operation of the receiver following a momentary high voltage surge.
References Cited (Backward Citations)
US2892028A
Cited
US3179743A
Cited
US3202865A
Cited
US3546536A
Cited
US3569621A
Cited
US3560650A
Cited
US3576946A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-19 | 1976-03-20 | 1976-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-19 | 1980-03-20 | 1980-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-19 | 1984-03-20 | 1984-09-19 | $7700.00 | Window Closed / Lapsed |