US 4,414,492 A · Electronic ballast system

Abstract

An electronic ballast system includes a first capacitor (C.sub.2) electrically coupled to the first filament (30) of a gas discharge tube (12) and becomes the power supply of the gas discharge tube (12) subsequent to both its charging and discharging operations. The collector (38) of a transistor (Tr) is connected to the first capacitor (C.sub.2). The primary winding (22) is connected to the first capacitor (C.sub.2) and the collector (38) of the transistor (Tr) in parallel relation. The transformer (t) includes a secondry winding (24) which is connected on opposing ends thereof in feedback relation to the base (44) and emitter (42) of the transistor (Tr). Pulses of opposing current polarity (122 and 124) generated through the secondary winding (24) alternately provide conducting and non-conducting states for transistor (Tr) to discharge and charge the first capacitor (C.sub.2) through gas discharge tube (12) to provide a power source for operation of gas discharge tube (12). The combination provides voltage limiting preventing the kick back voltage from the primary winding (22) to exceed a safe operating limit of the transistor (Tr) and allows use of the energy to produce visible light output instead of heat.

Claims36

Dependent claims

An electronic ballast system connected to an AC power source for a gas discharge tube having a first and second filament, comprising:

(a) a first capacitor electrically coupled in series to said first filament of said gas discharge tube;
(b) a transistor having a base, emitter, and collector, said collector being connected to said first capacitor;
and,
(c) transformer means having a primary winding coupled on a first end to said AC power source and on a second end to said first capacitor and said collector of said transistor, and a secondary winding coupled on opposing ends thereof in positive feedback relation to said base of said transistor and said emitter of said transistor, said primary winding being coupled in series relation with a parallel combination of (1) said emitter and collector of said transistor, and (2) said series coupled first capacitor and said gas discharge tube.

1 more element

A method of providing light output from a gas discharge tube having a first filament and a second filament contained therein including the steps of:

(a) charging a first capacitor coupled to said first filament on one end thereof, said capacitor being coupled to a primary winding of a transformer and a collector of a transistor element on a second end thereof, said transistor element being in a non-conducting state;
(b) simultaneously inducing a pulse voltage signal having a first polarity from a secondary winding of said transformer;
(c) applying said first polarity pulse voltage signal to the base of said transistor element for driving said transistor element to a conducting state;
(d) discharging said first capacitor to said first filament;
(e) simultaneously passing collector current of said transistor element through said primary winding and inducing a second polarity pulse voltage signal in said secondary winding;
(f) applying said second polarity pulse voltage to said base of said transistor element for driving said transistor element to a non-conducting state;
(g) inducing a voltage signal in said primary winding responsive to said transistor element being switched to said non-conducting state;
and,
(h) applying said voltage to said first capacitor for simultaneously (1) charging said first capacitor and (2) passing said voltage signal across said gas discharge tube.

6 more elements

Dependencies are inferred from the claim text.

Electronic ballast system

Life of this patent

Electronic ballast system

Life of this patent

Abstract

Claims36