High-pressure gas discharge lamp

A high-pressure gas discharge lamp comprising a lamp bulb hermetically enclosing a gas-filled discharge space, a functional layer, and a light emission opening, 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 the substantially elliptical or spherical region of the lamp bulb (1), the lamp being operable at a power such that both a devitrification of the lamp bulb and a condensation of the gas are substantially prevented,
• wherein the functional layer and the second layer are comprised of multiple sub-layers of the same material and the functional layer is partially co-extensive with the light emission opening, and
• wherein the multiple sub-layers alternate with one of higher refractive index being followed by another of the sub-layers having lower refractive index.

A high-pressure gas discharge lamp comprising at least a lamp bulb hermetically enclosing a gas-filled discharge space, a functional layer, and a light emission opening, 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 the substantially elliptical or spherical region of the lamp bulb (1), the lamp being operable at a power such that both a devitrification of the lamp bulb and a condensation of the gas are substantially prevented,
• wherein the functional layer is partially co-extensive with the light emission opening.

A lighting unit comprising 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 the 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 substantially prevented at the power consumption level of the lamp,
• wherein the functional layer is an interference filter comprised in particular of layers of SiO2 and ZrO2, wherein the functional layer has a total thickness of at least 3 mum, and wherein the functional layer is partially co-extensive with the light emission opening, and
• wherein the second layer is comprised in particular of layers of SiO2 and ZrO2.

A projection device comprising 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 the 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 substantially prevented at the power consumption level of the lamp,
• wherein the functional layer is an interference filter comprised in particular of layers of SiO2 and ZrO2, wherein the functional layer has a total thickness of at least 3 mum, and wherein the functional layer is partially co-extensive with the light emission opening, and
• wherein the second layer is comprised in particular of layers of SiO2 and ZrO2.