Power supply for gas discharge devices

Claim 2

A resonant supply circuit for generating high frequency, high voltage output to a gas-filled tube, comprising a. a transformer having leakage reactance and including a primary winding, a feedback winding and a secondary winding connected to the gas-filled tube, the transformer having a large magnetic air gap, b. a transistor having a base, an emitter and a collector, the collector being connected to the transformer primary winding and the base being connected to the transformer feedback winding to provide a base drive, c. in which voltage on the base of said transistor causes said transistor to conduct, said voltage serving to cause said transistor to conduct until said transistor saturation voltage begins to rise sinusoidally, d. circuit means connected to the base of said transistor to bias said transistor to delay application of conduction voltage to the base of the transistor until the collector voltage of the transistor is eliminated and to permit a rapid evacuation of charge carriers stored in the base-emitter junction of said transistor, and e. switch means connected to said primary winding, said switch means being operable when said transistor saturation voltage rises sinusoidally to remove said voltage from the base of said transistor to render said transistor non-conductive, said switch means further providing a path for rapid evacuation of charge carriers stored in the base-emitter junction of said transistor to render said transistor rapidly non-conductive.

Claim 3

A supply circuit according to claim 1 in which said switch means comprises a second transistor having a base, a collector and a grounded emitter, the base of said second transistor being connected to the transformer primary winding and the collector of said second transistor being connected to the base of said first transistor to provide said path.

Claim 4

A supply circuit according to claim 1 in which said circuit means comprises a biasing network connected between the base of said transistor and the transformer feedback winding.

Claim 5

A supply circuit according to claim 3 in which said biasing network comprises a capacitor in parallel with a resistor, said capacitor and resistor having a time constant much longer than the resonant period of said supply circuit.

Claim 6

A supply circuit according to claim 1 including means connected to the base of said transistor to cause said transistor to conduct when said circuit is initially energized.

Claim 7

A supply circuit according to claim 5 in which said means to cause said transistor to conduct comprises a relaxation oscillator.

Claim 8

A supply circuit according to claim 1 in which said circuit means comprises a biasing network connected to the emitter of said transistor, said network comprising a capacitor in parallel with a resistor.

Claim 9

A supply circuit according to claim 1 including means to prevent reverse current flow through the transformer feedback winding.

Claim 10

A supply circuit according to claim 8 in which said means to prevent reverse current flow comprises a fast recovery diode located between the base of said transistor and the feedback winding.

Claim 11

A supply circuit according to claim 1 including bypass means to remove the base drive from said transistor.

Claim 12

A supply circuit according to claim 10 in which said bypass means comprises a gate connected to said feedback winding which, when conducting, short circuits the feedback winding.

Claim 13

A supply circuit according to claim 11 in which said gate comprises a silicon-controlled rectifier, said rectifier being activated by an unbalance of said secondary winding.

Claim 14

A supply circuit according to claim 11 in which said gate comprises a triac, said triac being activated by an unbalance of said secondary winding.

Claim 15

A supply circuit according to claim 11 including a second transformer having a primary connected to a center tap of said secondary winding and having a secondary connected to said gate to activate said gate when said secondary winding is unbalanced.

Claim 16

A supply circuit according to claim 2 including a capacitor connected between the base of said second transistor and the transformer primary winding, said capacitor controlling said switch means and comprising means to cause resonating of said transformer. .Iadd.

Claim 17

A supply circuit for generating high frequency, high voltage output to a gas-filled tube, comprising a. a transformer having leakage reactance and including a primary winding a feedback winding and a secondary winding connected to the gas-filled tube, b. a power oscillator connected to said primary and feedback windings, said oscillator including high frequency tube actuation means connected to said primary winding for activating said tube, and means for controlling said tube actuation means connected to said feedback winding and said primary winding, and c. bypass means connected to said power oscillator and said secondary winding and operable to deactivate said tube actuation means if any loading on said secondary winding becomes unbalanced. .Iaddend. .Iadd.17. A supply circuit according to claim 16 in which said bypass means comprises a gate connected to said feedback winding which, when conducting, short circuits said feedback winding. .Iaddend. .Iadd.18. A supply circuit according to claim 17 in which said gate comprises a triac, said triac being activated by said unbalance of said secondary winding. .Iaddend. .Iadd.19. A supply circuit according to claim 17 including a second transformer having a primary connected to a center tap of said secondary winding and having a secondary connected to said gate to activate said gate when said secondary winding becomes unbalanced. .Iadd.20. A supply circuit according to claim 19 in which said gate comprises a silicon-controlled rectifier, said rectifier being activated by said unbalance of said secondary winding. .Iaddend.