Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Holger Moench

Hanns Ernst Fischer

Hans G Ganser

Gunther Hans Derra

Rob Snijkers

Carsten Deppe

Peter Luerkens

Dieter Leers

Guenther Hans Derra

Pavel Pekarski

Xaver Riederer

G&uuml;nther Hans Derra

Thomas Kr&uuml;cken

Thomas V Kr&uuml;cken

A high-pressure mercury vapor discharge lamp () comprising an envelope () of high temperature resistant material having a discharge vessel () and two electrodes () extending from two seal portions () into the discharge vessel (), the two electrodes having an electrode gap (de) smaller than or equal to 2.5 mm, preferably smaller than or equal to 1.5 mm, is described. The discharge vessel () contains a filling which essentially comprises the following substances: rare gas, oxygen, halogen consisting of chlorine, bromine, iodine, or a mixture thereof, as well as mercury in a quantity greater than or equal to 0.15 mg/mm3' The seal portions () have a cross-sectional area of between 6 mm2 and 20 mm2, preferably approximately 10 mm2. A method of manufacturing such a high-pressure mercury vapor discharge lamp () and a projector system for such a high-pressure mercury vapor discharge lamp () are also described.

High-pressure mercury vapor discharge lamp and method of manufacturing a high-pressure mercury vapor discharge lamp

An electronic circuit for operating a High Intensity Discharge (HID) lamp, in particular a Ultra High Pressure (UHP) lamp, such as those preferably used in image projectors. The circuit comprises a lamp ballast for offering a controlled lamp current for operating the HID lamp and a brightness sensor for generating and providing a sensor signal which represents the brightness of the light applied by the lamp to the image generator. The lamp ballast controls the lamp current such that the brightness of the light of the lamp remains constant. Brightness control is made possible throughout the entire operational life of the lamp, and the use of sensors of simple construction is made possible by an incorporation within the electric circuit of a filter that high-pass filters the sensor signal before it is supplied as a control signal to the lamp ballast.

Electronic circuit for operating a HID lamp, and image projector

A method of and a device for operating a gas discharge lamp which is fed with an alternating voltage or an alternating current and wherein the instantaneous power of the lamp is increased at given time intervals are used to form the electrodes. The value of an operational datum of the lamp which varies in time is continuously or discontinuously measured and the frequency of the alternating voltage or the alternating current (operating frequency) is selected in dependence on the measured values.

Method of and device for operating a gas discharge lamp

A high-pressure gas discharge lamp (HID or UHP lamp, or in general lamps with mercury fillings of between approximately 0.05 and 0.5 mg/mm ) is described with at least one electrode ( ) which is provided with a thickened, for example globular portion ( ) at its end lying inside a lamp vessel ( ). This portion is so dimensioned in dependence on operational parameters of the lamp and/or the diameter of the electrode rod that an electrode tip ( ) forms itself independently at said portion during the first hours of operation. This tip grows from the portion until its free end starts melting. The electrode tip is self-adjusting in this manner, so that an optimum electrode interspacing is maintained throughout lamp life. Furthermore, a method of manufacturing such a lamp is described.

High-pressure gas discharge lamp, and method of manufacturing same

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.

Long life discharge lamp operating circuit with reduced lamp flicker

A circuit arrangement is provided for operating a high pressure discharge lamp with a lamp current which, in successive periods, has opposite polarities. The lamp is provided with at least two main electrodes being spaced an electrode distance from each other. The circuit arrangement includes input terminals for connection to a supply source, output terminals for connection to the high pressure discharge lamp, and an element, coupled to the input terminals, for supplying the lamp current to the high pressure discharge lamp, which current, in successive periods, has a predetermined shape. The circuit arrangement is provided with an element for detecting a first parameter indicative of the electrode distance and forming a first signal dependent on the first parameter and with an element for reshaping the lamp current, in successive periods, in dependence of the thus formed first signal.

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Vaals, Germany

Holger Moench