Metallic halide electric discharge lamps

Claim 1

A gaseous electric discharge lamp comprising: an hermetically sealed vitreous light-transmissive outer envelope having electrical terminal means sealed thereinto for making electrical connection from an external power source to the interior of said envelope; a sealed, vitreous arc tube disposed within said outer envelope; first and second non-liquid metallic arc electrodes disposed within said arc tube and connected to electrical lead means sealed into said arc tube for making electrical connection through respective ends of said arc tube; a quantity of mercury disposed within said arc tube sufficient upon complete evaporation thereof during operation of said lamp to yield a particle pressure of approximately 101 to 1520 pascals within said arc tube; an ionizable medium disposed within said arc tube comprising a plurality of metallic halides; each metallic halide including a metal which emits electromagnetic radiation in the visible range of wavelengths in one of a plurality of predetermined multiple narrow emission lines, such that the total radiation emitted appears as white light; reflector means comprising a reflective coating disposed on the exterior surface of said arc tube to reflect long wavelength ultraviolet radiation and short wavelength infrared radiation having a wavelength of less than 1500 nanometers; and a cylindrical reflector disposed within said outer envelope and surrounding said arc tube and comprising a material which blocks transmission of infrared radiation having a wavelength of at least 1500 nanometers, said reflective coating and said cylindrical reflector cooperating for reflecting infrared and ultraviolet wavelengths inward so that said infrared and ultraviolet wavelengths are substantially removed from the light output of said lamp; and conductive means for supporting said arc tube within said outer envelope and making electrical connection from said electrical terminal means to said electrical lead means.