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Use of SrO coating/dope to Mo-foil of UHP-lamps to lower UHP ignition voltage

IP.com Disclosure Number: IPCOM000012595D
Publication Date: 2003-May-19
Document File: 1 page(s) / 19K

Publishing Venue

The IP.com Prior Art Database

Abstract

ID612651

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ID612651

Use of SrO coating/dope to Mo-foil of UHP-lamps to lower UHP ignition voltage

Standard UV-enhanced UHP lamps have ignition voltages for reliable ignition of about 1500V. This voltage is necessary to ignite the UV-enhancer (UVE). Ignition of the UVE requires two steps:

  • electrons have to be freed from the Mo-foil by applying a sufficiently strong electrical field
  • the electrical field has to be strong enough to cause breakdown in the UVE filling gas (Ar/Hg) once free electrons are present.

In actual UHP lamps the first step requires the highest voltage. Disclosed is an embodiment of an UHP-lamp in which said highest voltage step is lowered by doping the Mo-foil with a co-dope of SrO, BaO or CaO, for example SrO has a work function of 1.27-1.6 eV (for comparison, conventional Mo-foil contains 0.5% Y2O3-dope with a work function of 2.0-3.87 eV). Experiments show the positive effect of the dope on the lowering of the ignition voltage of the UHP-lamps.