Patent ID: 8836217

Claim:
A mercury-free metal halide lamp for a vehicle, comprising: an airtight vessel provided with a light-emitting part with a discharge space inside; a metal halide and a rare gas sealed in the discharge space; and a pair of electrodes disposed so that the tip ends of the respective electrodes face each other in the discharge space, wherein the electrodes and the discharge space do not contain thorium, and when an electric power supplied to the lamp during a stable lighting period is represented by P (W), a value obtained by adding up the electric power supplied to the lamp during a period between 1 second and 40 seconds after the startup of the lamp is represented by W L (W), and the diameter of the electrodes is represented by D (mm), P (W) satisfies 20≦P≦30 and W L /D (W/mm) satisfies 4300≦W L /D≦7400.