Patent ID: 7453205

Claim:
A high-pressure gas discharge lamp which comprises at least a lamp bulb ( 1 ) hermetically enclosing a gas-filled discharge space ( 21 ), a functional layer ( 3 ), and a light emission opening ( 5 ), the latter two being arranged on an outer surface of a substantially elliptical or spherical region of the lamp bulb, wherein a second layer entirely covers mutually opposed cylindrical regions of the lamp bulb ( 1 ), arranged at respective ends of said substantially elliptical or spherical region of the lamp bulb ( 1 ), while the lamp is operated at a power such that a devitrification of the lamp bulb ( 1 ) and a condensation of the gas are prevented at the power consumption level of the lamp, wherein the functional layer is an interference filter comprised in particular of layers of SiO 2 and ZrO 2 , and wherein the functional layer has a total thickness of at least 3 mum and the functional layer is partially co-extensive with the light emission opening, and wherein the second layer is comprised in particular of layers of SiO 2 and ZrO 2 .