VEHICLE DISCHARGE LAMP, VEHICLE DISCHARGE LAMP DEVICE, LIGHTING CIRCUIT COMBINED TYPE VEHICLE DISCHARGE LAMP DEVICE, AND LIGHTING CIRCUIT

摘要

Provided is a mercury-free vehicle discharge lamp that is stably lighted with a power of 18 to 30 W in a steady time. The lamp is defined in a light-emitting portion (11). A discharge medium including a metal halogen compound and a rare gas are sealed into the lamp. The lamp also has a discharge space in which electrodes (32) are disposed and satisfies the following equation. -40 = (a - 35) × 5.5 + (x - 13.5) × 10 + (1.85 - t) × 100 + (2.5 - d) × 100 = 40 where, a : power [W] supplied in a stable lighting time and having a value of 18 or more and 30 or less x : pressure [atm] of the rare gas sealed into the discharge space t : thickness [mm] of the region where the radial thickness of the light-emitting portion becomes maximum d : inner diameter [mm] of the region where the radial thickness of the light-emitting portion becomes maximum