US 4,904,907 A · Ballast circuit for metal halide lamp

Abstract

A ballast circuit and method of operating gas discharge lamps are disclosed. The ballast circuit generates a relatively low frequency regulated square-wave current which advantageously provides for operating the gas discharge lamps during their run mode. The square-wave current delivered to the electrodes of the gas discharge lamp reduces or substantially eliminates the cataphoresis effects typically created by D.C. and 60 Hz operation of the gas discharge lamp while also reducing or substantially eliminating the detrimental acoustics resonance effects typically created by operating the gas discharge lamps at relatively high frequency of excitations.

Claims16

Dependent claims

A method of operating a gas discharge lamp having a pair of electrodes and containing a fill of excitable ingredients comprising the steps of;

(A) applying a relatively high voltage across said pair of electrodes to cause the excitation of said ingredients;
(B) delivering a square-wave of current to said pair of electrodes to maintain said excitation of said ingredients, said current being of an amplitude in the range of about 0.2 amperes to about 2.0 amperes and a repetition rate of about once every 1.0 milliseconds to about once every 0.1 millisecond and;
(C) detecting said level of current delivered to said electrodes and terminating said current if a predetermined value is detected.

Dependencies are inferred from the claim text.

Ballast circuit for metal halide lamp

Life of this patent

Ballast circuit for metal halide lamp

Life of this patent

Abstract

Claims16