HIGH-PRESSURE DISCHARGE LAMP, LIGHTING OPTICAL DEVICE USING THIS HIGH-PRESSURE DISCHARGE LAMP, AND IMAGE DISPLAY DEVICE USING THIS LIGHTING OPTICAL DEVICE

摘要

PROBLEM TO BE SOLVED: To realize high efficiency, long lifetime and high color temperature by setting a linear transmittance and a tube wall load of a light emitting tube of the translucent ceramics, which has a pair of electrodes and in which the light emitting material such as mercury, the inert gas, metal or metal halide is sealed, at a specified value. SOLUTION: A light emitting tube 1 has a linear transmittance at 35% or more and a tube wall load WL at 30-100 W/cm2 , and the light emitting tube 1 is desirably made of YAG, yttria or aluminum nitride. The light emitting tube 1 is made of multi- crystal alumina, YAG, yttria or aluminum nitride, and has a mean crystal grain diameter G m and thickness (t) mm (but 1=G=30, 0.8=t=2.5) so as to prevent the generation of breakdown. As a light emitting material, lithium halide or indium halide can be desirably used together. Lamp efficiency and color temperature of the reflected light at the time of operating a lighting optical device, which is formed of a short-arc and high-pressure discharge lamp including the light emitting tube 1 and a recessed surface reflecting mirror 9 having a reflecting surface of a deposition film of TiO2 -SiO2 , with a rated power are improved.