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US3840784A Expired / Lapsed US ⏱️ 0.0 years remaining

High voltage protection circuit

Assignee: Eastman Kodak Co
•
Filing: 1973-04-05
•
Granted: 1974-10-08
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Expires: 1993-04-05
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Abstract

Abstract A high voltage protection circuit for cathode ray tube apparatus such as television recievers and film video players. The protection circuit effects shut down of the high voltage power supply which supplies a high voltage to the cathode ray tube when the output of the high voltage regulator exceeds a predetermined value. The high voltage power supply is driven by a horizontal driver circuit which is switched on and off by a voltage controlled oscillator. The voltage regulator senses the output of the high voltage supply and controls the voltage switched by the horizontal driver circuit. The protection circuit includes a sensing circuit for sensing the output of the voltage regulator, an impedance circuit connected to ground having a high impedance state and a low impedance state and a bistable control circuit connected between the sensing circuit, the voltage controlled oscillator and the impedance circuit. When the output voltage of the voltage regulator is sensed by the sensing circuit to exceed a predetermined value, the bistable control circuit is switched to a conducting state to thereby switch the impedance circuit from a high impedance state to a low impedance state. The voltage controlled oscillator is thus provided with a low impedance path to ground through the bistable circuit and low impedance circuit to shut the oscillator off and to shut down the high voltage power supply.

Inventors

  • 👤 C Schauffele

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-29 17:38
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/20; H02H3/00; H02H3/20; H02H3/202; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/20

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 109 words
In flying spot scanner cathode ray tube apparatus having a voltage controlled oscillator and a high voltage regulator, a high voltage protection circuit comprising: a voltage divider circuit connected between a reference voltage and the output of said voltage regulator, said voltage divider circuit including a variable resistor having a voltage pick-off terminal; a diode circuit having first and second terminals; and a semiconductor device having first, second and third terminals respectively connected to the input of said voltage controlled oscillator, to the pick-off terminal of said variable resistor, and to said first terminal of said diode circuit, said second terminal of said diode circuit being connected to ground.
Claim 2
Dependent Claim 109 words
In flying spot scanner cathode ray tube apparatus having a voltage controlled oscillator and a high voltage regulator, a high voltage protection circuit comprising: a voltage divider circuit connected between a reference voltage and the output of said voltage regulator, said voltage divider circuit including a variable resistor having a voltage pick-off terminal; a diode circuit having first and second terminals; and a semiconductor device having first, second and third terminals respectively connected to the input of said voltage controlled oscillator, to the pick-off terminal of said variable resistor, and to said first terminal of said diode circuit, said second terminal of said diode circuit being connected to ground.
Claim 3
Dependent Claim 31 words
The circuit of claim 1 wherein said semiconductor device comprises a controlled rectifier having anode, cathode and gate terminals respectively comprising said first, second and third terminals of said semiconductor device.
Claim 4
Dependent Claim 22 words
The circuit of claim 2 wherein said diode circuit includes a pair of serially connected diodes connected in parallel with a resistor.
Claim 5
Dependent Claim 92 words
The circuit of claim 1 wherein said semiconductor device comprises first and second transistors respectively having base, emitter and collector electrodes, wherein the emitter of said first transistor is connected to said pick-off terminal of said variable resistor, the collector of said first transistor is connected to the base of said second transistor, the collector of said second transistor and the base of said first transistor are connected together and to the first terminal of said diode circuit and the emitter of said second transistor is connected to said voltage controlled oscillator.
Claim 6
Dependent Claim 22 words
The circuit of claim 2 wherein said diode circuit includes a pair of serially connected diodes connected in parallel with a resistor.

References Cited (Backward Citations)

No citation records indexed.

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1977-10-07 1978-04-08 1978-10-08 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1981-10-07 1982-04-08 1982-10-08 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1985-10-07 1986-04-08 1986-10-08 $7700.00 Window Closed / Lapsed

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