Compact halogen-cycle incandescent lamp, and lamp unit utilizing such lamp as a light source

Abstract

A compact halogen-cycle type incandescent lamp is provided with an envelope that is composed of a selected hard glass (a borosilicate or an aluminosilicate type glass for example) and then dosed with an amount of bromine which is correlated with the glass composition in such a manner that it counteracts the deleterious release of water-vapor forming constituents by the glass envelope when the lamp is energized and the glass is hot. The halogen-cycle lamp is especially adapted for use as the concentrated light source in a general service type lamp or a sealed-beam headlamp and, when so employed, has a fill gas pressure that is so correlated with the gas pressure of the non-oxidizing atmosphere in the outer envelope that the total gas pressure does not exceed 1,000 Torr and the envelope of the halogen-cycle lamp operates at a temperature which is sufficient to reliably sustain the halogen cycle but is below the softening temperature of the particular hard glass from which the halogen lamp envelope is made. In the case of a lamp intended for general lighting or residential illuminating purposes, the halogen-cycle lamp component contains iodine rather than bromine since iodine-cycle lamps produce a "warm" light effect.

Dependencies are inferred from the claim text.