| abstract |
The apparatus has a light transmitting bulb (21) for confining a discharge therein, a fill (22) sealed within the light transmitting bulb (21) and including a rare gas and a metal halide emitting a continuous spectrum by molecular radiation, and a discharge excitation means for applying electrical energy to the fill and for starting and sustaining an arc discharge, the metal halide including one kind of halide selected from the group consisting of an indium halide, a gallium halide, and a thallium halide, or a mixture thereof, wherein the light transmitting bulb (21) has no electrodes exposed in the discharge space and this construction utilizes the continuous spectrum of molecular radiation of the metal halide, thereby achieving high colour rendering properties and high luminous efficacy simultaneously without using mercury as the fill. |