Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh

Patent-Treuhand-Gesellschaft F. Elektrische Gluehlampen Mbh

Bernhard Altmann

Peter Schade

Dietrich Fromm

Hans-Joachim Lunk

Ralf Seedorf

Alfred Gahn

Wolfram Graser

Michael Salmen

Juergen Maier

Andreas Ponnier

Dietmar Illig

Juergen Begemann

Martin Fait

Alfred-Georg Gahn

Klaus Stedele

Rudolf Richter

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 electrode component according to the invention is produced by means of the metal powder injection molding method. As a result, complex shapes can be realized for the electrode.

Powder metal electrode component for discharge lamps

The electrode of tungsten material has a cylindrical shaft and a conical tip, in which the conical tip is made essentially by radial deformation, such as hammering or cross-rolling, of the tip portion (9) of the electrode blank (5). This changes the grain structure to be converging. A flat top or plateau (10) can be ground at the very end of the tip.

Electrode for a high-pressure discharge lamp, and methods of its

To essentially eliminate aluminum and silicon as contaminants in a doped tungsten wire, the tungsten wire is obtained by mechanical working of reduced tungsten blue oxide which contains as a primary or major constituent a special hexagonal ammonium tungsten bronze of the general formula (NH.sub.4).sub.X (NH.sub.3).sub.y WO.sub.3. A liquid doping step is carried out by adding a solution containing potassium nitrate, the special doped ammonium tungsten bronze forming preferably more than 70% by weight of the overall tungsten blue oxide. The special hexagonal ammonium tungsten bronze is made by decomposing ammonium paratungstate in an ammonium atmosphere, preferably at a temperature between about 400.degree. and 550.degree. C.

Method of manufacturing a non-sag tungsten wire for electric lamps

To improve the arc stability of high-pressure discharge lamps, particularly f power ratings of up to about only 250 W, the cathode (4) is formed as an elongated, essentially cylindrical base body (8) having a tapering, conical region (9) terminating in a tip (10). The base body (8), only, is covered with a carbide coating along its length, except for an end portion for electrical connection; the carbide coating starts at the junction or transition between the cylindrical base body portion and the conical end portion. This cathode construction is easier and cheaper to make than prior art cathodes, by coating an essentially cylindrical cathode and then etching or grinding and polishing the tapering end region (9). The electrode is preferably made essentially of tungsten, doped with thorium oxide present up to about 0.6%, optionally also potassium, aluminum and silicon in tiny amounts. The electrode spacing is between 0.4 to 0.8 mm, and when used as a mercury high-pressure discharge lamp, filled with 70 to 130 mg per cubic centimeter mercury; when used as a xenon lamp, the xenon fill is preferably present at a cold fill pressure of between about 2 and 15 bar.

High-pressure discharge lamp, particularly low-rated power discharge

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Langerringen, Germany

Bernhard Altmann