Albert J Peng

US Patent:

59231262, Jul 13, 1999

Filed:

Aug 9, 1996

Appl. No.:

8/708005

Inventors:

Kevin Yang - Chula Vista CA
Chien F. Chao - Rancho Palos Verdes CA
John Yu - Torrance CA
Albert Peng - Long Beach CA
Feng Hu - Palos Verdes Estates CA

Assignee:

Philips Electronic North America Corporation - New York NY

International Classification:

H05B 3702

US Classification:

315102

Abstract:

An electronic ballast for a fluorescent lamp includes a delay triggered circuit which, upon expiration of a predetermined period during which the lamp filaments, constituting opposite electrodes of the lamp, are preheated, applies high frequency operating voltage across the opposite electrodes of the lamp beginning with a transition from a condition of no voltage to a condition of full rated voltage which occurs within one cycle of the high frequency voltage. The sharp transition from zero "glow current" to full "arc current" at the end of the preheating period has been found to increase the life of lamps in the number of on-off starts, particularly with respect to lamps of poor quality. The rapid transition is possible because the ballast uses the same inverter and transformer for supplying preheating and operating voltages. The operating voltage is applied between the opposite electrodes of the lamp via an electronic bi-directional switch, controlled by a preheating delay RC timing circuit.