Koninklijke Philips Corporation N.v.

Hans Antonie Feijen

Carsten Deppe

Christofher Daniel Charles Hooijer

Tom Munters

Roy Hendrik Anna Maria Van Zundert

Sander Habets

John Evarist Karel Georges De Clercq

A method for operating a projection system () is described, wherein a brightness level (B, B, B, B, B, B) in an image (IM) is represented by the total length of a number of light switch-on phases within a particular image cycle (VT). A high pressure discharge lamp () of the projection system () is operated via a lamp driver with an essentially square-wave alternating current (IL) SO that an overshoot sequence (), which occurs in the alternating current (IL) after a current zero crossing during operation of the high pressure discharge lamp (), has a frequency so high that for each possible brightness level at least one full period (P) of the overshoot sequence () lies essentially within a light switch-on or switch-off phase (ts) following the zero crossing. A projection system () and a lamp driver () for a high pressure discharge lamp () in such a projection system () are also described.

Projection system and method for operating a projection system to compensate for overshoot sequence

A circuit arrangement for operating a high pressure discharge lamp comprises a down converter equipped with an output capacitor and a commutator equipped with an ignition choke. The amplitude of the DC current generated by the down converter is controlled by means of a control circuit. To suppress resonance of the ignition choke with the output capacitor caused by commutation of the DC current, the current reference signal of the current control is adjusted in dependency of the power consumed by the lamp and in dependency of the lamp voltage immediately before and after each commutation.

Circuit arrangement for operating a high pressure discharge lamp

Growing community of inventors

Oss, Netherlands

Hans Antonie Feijen