| 摘要 |
PROBLEM TO BE SOLVED: To restrain abnormal luminescence such as a strong orange light just after starting, which is caused by not using mercury in a metal halide lamp, wherein mercury having a bad influence on environment is not used. SOLUTION: This metal hide lamp 1 is equipped with a discharge container 2 having a discharge space 2a and a sealing part 2b. In the discharge container 2, a mixed luminous material 6 substantially constituted by two or more kinds of metal halide and a rear gas are contained, and a discharge medium substantially containing no mercury is enclosed. A pair of electrodes 3 are disposed to face to each other in the discharge space 2a. The metal halide lamp 1 having no mercury satisfies an expression, (A/B)×D}/(C/500)<6> <=3.11 when an adhesion amount of the mixed luminous material 6 existing in a range of within 0.2 mm around an electrode shaft 3a at turning off of the lamp is A (mg), a capacity of the discharge container 2 is B (cc), a melting point of the mixed luminous material 6 is C (K), and a ratio between maximum electricity W1 at starting of the lamp and electricity W2 at a stationary state (W1 /W2 ) is D. |
