PURPOSE: To weaken luminescent color of yellow or orange and strengthen redish luminescent color by using much of lithium in place of sodium as an alkali metal which is sealed to prevent the fluctuation of an arc.
CONSTITUTION: Metal halides, mercury, and a rare gas are sealed in an arc tube into which electrodes 4 are arranged and a metal halide lamp is operated in bulb wall loading of 20W/cm2 or more. As the metal halides, halides of Li, Na, Sn, and Tl are used. The sealing amount of the metal halides is specified in 5.0μ mole/cc≤Li+Na≤12.0μ mole/cc, 3.5μ mole/cc≤Sn≤6.0μ mole/cc, 0.2 molar ratio ≤Ti/Sn≤4.0 molar ratio, and Na/Li≤0.4. Luminescent color of yellow or orange in the vicinity of 580-590nm caused by Na is weakened and redish luminescent color is strengthened.
INUKAI SHINJI
NISHIZAWA MAKOTO
SANO HISANORI
