High pressure mercury vapor discharge lamp, and lamp unit

Abstract

A high-pressure mercury-vapor discharge lamp according to the present invention includes: an emission tube, which is made of quartz glass and which has a substantially ellipsoidal inner space; at least mercury and a rare gas, which are sealed in the inner space of the emission tube; and at least two electrodes, which are arranged in the inner space of the emission tube so as to face each other. The lamp satisfies W≧150 watts, P≧250 atm, t≦5 mm and rl≦0.0103×W−0.00562×P−0.316×rs+0.615×t+1.93, where W [watts] is the power of the lamp during its lighting operation, P [atm] is an operating pressure in the inner space of the emission tube, rs [mm] is the shorter radius of the inner space, rl [mm] is the longer radius of the inner space (where rl≧rs), and t [mm] is the thickness of a swollen portion that defines the inner space.

Dependencies are inferred from the claim text.