Mercury lamp of the short arc type having specific relationship with various dimensions of the bulb and UV emission device

摘要

To devise a mercury lamp of the short arc type with high radiant efficiency and increased arc stability which meets the demand for increasing the amount of radiation from the light source. In a mercury lamp of the short arc type, a cathode and an anode are disposed opposite one another within an arc tube filled with mercury and a rare gas. At least argon (Ar) and/or krypton (Kr) in an amount from 1.0 to 8.0 atm at room temperature is added as the rare gas. In addition, the relationship between various dimensions of the lamp is fixed such that conditions 0.3≦X/L≦0.6, (X+5)/D≦0.85, and (L−(X+5))/D≦0.85 are satisfied, L (mm) being the length of the bulb in the axial direction, X (mm) being the length of the cathode which projects in the axial direction into the emission space, and D (mm) being the maximum outside diameter of the bulb in the radial direction.