Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-treuhand-gesellschaft Fuer Elektrische Gluehlampen Mbh

Wolfram Graser

Andreas Huber

Dietrich Fromm

Josef Osterried

Alwin Veser

Bernhard Altmann

Dieter Schmidt

Peter Schade

Flickering phenomena in gas discharge lamps are undesired in projection technology, in particular. According to the invention, the problem is solved by setting a lamp operation which does not form a focal spot. A specific control structure which includes a cascade structure and feedforward control is proposed for implementing this operation.

Stabilizing the operation of gas discharged lamps

A sintered electrode of high-melting metal (for example tungsten) is produced from spherical metal powder having a well defined particle size. The mean particle size is from 5 to 70 &mgr;m. The particle size distribution covers a range from at most 20% below to at most 20% above the mean particle size.

Sintering electrode

The high-pressure sodium discharge lamp of low power described here is chcterized by a very high xenon cold filling pressure of at least 1 bar. The pressure ratio to the sodium operating pressures lies between 10 and 30. Luminous efficacies of approximately 100 lm/W and more can be obtained with a lamp power of 50 to 100 W.

High pressure sodium lamp of low power

The method is suitable to make sodium high-pressure discharge lamps operag operating under saturated condition. After placing and melt-sealing a first electrode system into the discharge vessel, sodium is introduced in the form of NaN.sub.3 through the second end of the vessel. Upon heating of the second end, and due to heat conduction, the NaN.sub.3, collected at the first end, dissociates, resulting in a sudden pressure rise due to liberation of nitrogen within a vacuum. As soon as the nitrogen has dissipated, noble gas to cool the first end is introduced, and the second melt seal is then made. The noble gas may, at the same time, form an ignition gas, or a gas mixture for the discharge lamp. One or more half-finished lamps are preferably held in a holder structure which has vertical bores leaving a gap of between 0.2 to 3 mm between the wall surface of the bore and the vessel and, as such, are introduced into a vacuum furnace, where the pressure can be monitored.

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Munich, Germany

Wolfram Graser