Patent · US Expired

Long life discharge lamp operating circuit with reduced lamp flicker

US6239556A · kind A · utility

13Cited by

1References

18Claims

0Family size

Assignee

U.S. Philips Corporation · US

Inventors

Gunther Hans Derra · Aachen, DE
Hanns E. Fischer · Stolberg, DE
Hans G. Ganser · Stolberg, DE
Thomas Krücken · Aachen, DE
Holger Moench · Vaals, NL
Rob Snijkers · Landgraaf, NL

Key dates

Filing date	Dec 15, 1999
Grant date	May 29, 2001
Priority date	—
Expiry date	Dec 15, 2019

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY10S315/05
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

A circuit for operating a high pressure discharge lamp comprising input terminals for connection to a supply voltage source, output terminals for connecting the high pressure discharge lamp, and apparatus, coupled to the input terminals, for supplying an alternating lamp current to the high pressure discharge lamp. The lamp current in each period has a mean value Im. At the start of each period, the lamp current is lowered with respect to the mean value Im so as to allow for stable diffuse attachment on the cathodic phase electrode. The circuit is particularly suited for operating a lamp in an optical projection system.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.