DISCHARGE BULB

摘要

A discharge bulb is equipped with a discharge light emitting chamber tube in which discharge electrodes are provided face to face and a luminescent material is filled at the center of the ceramic tube in longitudinal direction. A metallic pipe is jointed into the pore of a tube end communicating with the discharge light emitting chamber. The rear end of an electrode rod inserted into the pipe with its tip protruding into the discharge light emitting chamber to constitute an electrode is jointed to the protruding tip of the pipe. A constricted part is arranged in the part between the tube center corresponding to the discharge light emitting chamber of the ceramic tube and the tube end. The thickness of the tube wall of the tube end is augmented to enhance the thermal shock resistance of the tube end. The thickness of the tube wall at the constricted part is reduced to suppress heat transmission from the discharge light emitting part to the tube end and to improve the light emission efficiency of the arc tube main unit.