Luminaire incorporating arc tube preheater

Abstract

A high intensity discharge (HID) lamp luminaire including a heater for eating the lamp arc tube prior to starting. Preheating the arc tube decreases the amount of damage done by starting, and additionally reduces warm-up time. An illumination reflector has an open end for light output, and an apex. The arc tube contains an ionizable fill and a pair of electrodes and is mounted generally in front of the rear apex, such as within the illumination reflector between the open end and the apex. At least a portion of the illumination reflector is a dichroic element which is relatively reflective of visible light and relatively transmissive of infrared radiation. A source of infrared radiation, such as an incandescent heat lamp, is located outside the illumination reflector, such as generally behind the apex, for directing infrared radiation through the dichroic element portion of the illumination reflector to heat the arc tube. A shield is located within the illumination reflector between the open end and the apex, and serves the multiple purposes of reflecting infrared radiation for enhancing heating of the arc tube by the source of infrared radiation, blocking light from the arc tube (which light includes ultraviolet radiation) from radiating directly out of the open end of the reflector, and as a shatter shield in the event of non-passive failure of the arc tube. The illumination reflector absorbs ultraviolet radiation.