Power supply for gas discharge devices
First Claim
1. A resonant supply circuit for generating high frequency, high voltage output to a gas-filled tube, comprisinga. 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, ande. 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.
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Accused Products
Abstract
A low current, high voltage power supply for gas discharge devices, such as neon tubes. The power supply has a free-running oscillator which generates a high frequency voltage signal which drives a light-weight, compact transformer. The oscillator has a power transistor drive, and a second transistor is used to remove the base drive of the power transistor to render it non-conductive. The second transistor also provides a path for rapid evacuation of the charge carriers stored in the base-emitter junction of the power transistor to rapidly render it non-conductive when the second transistor is energized. A safety bypass circuit is provided should a fault occur with the gas discharge device.
54 Citations
15 Claims
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1. 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.
Specification