Patent ID: 7227309
Filing Date: 2007-06-05
Classification: H01J

Abstract:
1. A metal halide lamp comprising a light emitting bulb of translucent ceramic that comprises a light emitting portion and tubular portions, the tubular portions being connected to a pair of ends of the light emitting portion, wherein the light emitting portion and the tubular portions are integrally formed in a mold, wherein the light emitting portion comprises a liquid holding portion on an inner surface of the light emitting portion so as to hold a liquefied substance that moves on the inner surface toward one of the tubular portions, wherein the liquid holding portion is formed on a tapered portion of the light emitting portion at a position between a maximum diameter portion and the tubular portion, and the liquid holding portion is formed of a projection or a groove to form a ring on the inner surface of the light emitting portion, and wherein the internal diameter d of the light emitting bulb at the liquid holding portion satisfies 0.4D<d<0.7D, where D is an internal diameter of the light emitting bulb at the maximum internal diameter portion of the light emitting portion, wherein the liquid holding portion is spaced longitudinally from a nearest of the tubular portions, and wherein the tapered portion of the light emitting portion narrows in diameter to form a cone shape.