Patent ID: 6639361
Filing Date: 2003-10-28
Classification: H01J

Abstract:
A metal halide lamp comprisingan arc tube of translucent ceramic, in which a metal halide is filled; and a pair of electrodes provided in said arc tube, each said electrode having an electrode bar and an electrode coil wrapped around the electrode bar; wherein an end face of said electrode coil on the front end side of said electrode bar is shaped to form a plane substantially perpendicular to an axis of said electrode bar, and the following relationship is satisfied: 0.00056Ã—W+0.061&lE;&agr;&lE;0.0056Ã—W+1.61 where &agr; is a length expressed in mm of a portion of said electrode bar protruding from the plane of the end portion of said electrode coil and W is the lamp power expressed in Watts.