Electrode for a metal halide lamp

摘要

A metal halide lamp using a ceramic arc tube in which less lamp flickering occurs, the flux maintenance factor during the lifetime is high and the possibility of lamp break-off is low. The metal halide lamp includes an arc tube 1 in which iodide pellet of metal halide is filled, and a pair of electrodes are arranged in the ceramic arc tube so that the electrode coils are facing each other. The following relation is satisfied: <DF>0.00056 x W + 0.061 </= alpha </= 0.0056 x W + 1.61 </DF> where alpha (in mm) denotes a length of the portion of the electrode bar protruding from the end face of the electrode coil and W (in Watt) denotes the lamp power. <IMAGE>