Koninklijke Philips Corporation N.v.

Philips Intellectual Property & Standards Gmbh

Gerhard Hebbinghaus

Jozef Merx

Erik Paul Boonekamp

Hendrik Adrianus Van Sprang

Mathias Hubertus Johannes Van Rijswick

The invention relates to a method for the thermal treatment of tungsten electrodes having a fibrous mocrostructure and being free from thorium oxide for high-pressure discharge lamps, to such a tungsten electrode free from thorium oxide, to a method of manufacturing a high-pressure gas discharge lamp with at least one such tungsten electrode free from thorium oxide, to a high-pressure gas discharge lamp with at least one such tungsten electrode free from thorium oxide, and to a lighting unit with at least one such high-pressure gas discharge lamp.

Method for the thermal treatment of tungsten electrodes free from thorium oxide for high-pressure discharge lamps

The invention relates to a Hg free high pressure discharge lamp having a quartz envelope and a halide filling, wherein the lamp comprises at least one electrode which comprises tungsten and &#x2267;0 wt. % and &#x2266;0.5 wt. % thorium and whereby the lamp comprises at least one Mo-containing lead-in wire and/or foil whereby the Mo containing wire and/or foil comprises TiOand having a characteristic life time of &#x2267;2500 h and &#x2266;7500 h according to the EU Carmaker cycle test.

Lamp with an improved lamp behaviour

The electric lamp comprises a lamp vessel ( ) which transmits visible light and which accommodates a light source ( ). The electric lamp comprises a light-absorbing medium ( ). The lamp vessel ( ) is covered with an optical interference film ( ) which comprises layers composed of a first layer of silica and a second layer of a material having a relatively high refractive index which alternate with each other. According to the invention, light from the light source ( ) travels through the light-absorbing medium ( ) before reaching the interference film ( ). Preferably, the light-absorbing layer ( ) is disposed between the lamp vessel ( ) and the interference film ( ). Alternatively, the light-absorbing layer is contained in a wall of the lamp vessel. Preferably, the interference film ( ) reflects substantially in the same wavelength range as that wherein the light-absorbing medium ( ) absorbs, preferably in the range from 570 to 620 nm. Preferably, the electric lamp emits, in operation, colored light but has a color-neutral appearance when the lamp is in the off-state. The light-absorbing layer ( ) preferably predominantly comprises Nd O , CoAl O , Fe O , ZnFe O , ZnO.Fe O or BiVO .

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Jülich, Germany

Gerhard Hebbinghaus