Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Ghaleb Natour

Robert Peter Scholl

Rainer Hilbig

Achim Gerhard Rolf Koerber

Johannes Baier

Xaver Riederer

Walter Schlager

The invention relates to a high-pressure discharge lamp with a discharge vessel having a filling comprising&#x2014;a rare gas, for example argon, &#x2014;mercury, and &#x2014;chlorine, wherein the filling quantities of mercury [Hg] and chlorine [Cl] comply with the following conditions: &#x2014;[Hg](E[Cl]200 (&#x3bc;mole/cm3)2, &#x2014;[Cl] &#xa3; 10 &#x3bc;mole/cm3. The condition [Hg](E[Cl]200 (&#x3bc;mole/cm3)2 achieves HgCl vapor pressures in the discharge sufficient for generating significant radiation components of the B2S+-X2S+ band system of this molecule. The condition [Cl] &#xa3; 10 &#x3bc;mole/cm3 serves to limit the chemical aggressiveness of the chlorine filling, in particular to limit the attacks on the wall and electrodes and thus to achieve longer lamp lives. The addition of chlorine-binding metals, in particular of germanium, leads to a further improvement in the radiation and life properties of the lamp.

High-pressure discharge lamp with mercury chloride having a limited chlorine content

The high-pressure discharge lamp comprises a lamp vessel ( ) in which an anode ( ) and a cathode ( ) are disposed spaced apart by an electrode distance D of 1-2 mm, the anode ( ) having a tip ( ) with a blunt end surface S. The area of the end surface S in mm and the lamp current I in amperes satisfy a relationship according to which 0.09&lE;S/I&lE;0.16, with 3.5&lE;I&lE;8.0 amperes. The ionizable filling containing metal halide comprises an amount of mercury between 65-125 mg/cm . The power range of the lamp is between 200 and 400 watts. The calculated power gap ratio, PGR&equals;P/D, is over 120 W/mm. The lamp is suitable for comparatively high brightness applications and at the same time is comparatively stable and has a comparatively long life.

High-pressure discharge lamp

A light transmitting discharge vessel encloses a discharge space, sealed in a gas-tight manner, in which electrodes connected to current conductors which extend to the exterior are disposed. A filling in the discharge vessel comprises a rare gas, a buffer gas and at least one transition metal halide chosen from the halides of hafnium, zirconium and tantalum. Each of the electrodes comprises an electrode part containing a carbide chosen from the carbides of hafnium, zirconium and tantalum. As a result diffusion of transition metal from the plasma into the electrode is strongly suppressed so that the lamp keeps very good color rendering properties throughout its operation.

High pressure metal halide lamp

The high pressure metal halide lamp has in a light transmitting discharge vessel discharge electrodes and a filling made of a rare gas, a buffer gas and at least one halide chosen from hafnium and zirconium bromide and chloride. The filling also includes a metal chosen from tin, tantalum and antimony in elementary form and is free from iodine in an amount exceeding 0.5 .mu.mol/cm.sup.3 discharge space. The lamp has considerably improved light generating properties.

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Roetgen, Germany

Ghaleb Natour