Patent ID: 6984938
Filing Date: 2006-01-10
Classification: H01J

Abstract:
1. A metal vapor discharge lamp having an arc tube, wherein the arc tube includes a container made of translucent ceramic, the container being divided into a main tube portion and two narrow tube portions respectively extending out from both ends of the main tube portion, a discharge space is formed in the main tube portion with a light emission metal being enclosed in the discharge space, an electrode is deposited in each narrow tube portion, a coil being wound around the electrode at an end thereof facing the discharge space, an electrode supporting member is inserted in each narrow tube portion and connected to the other end of the electrode, the arc tube is sealed by a sealing material that is inserted into each space between each electrode supporting member and each narrow tube portion, with an end of each narrow tube portion located on the outside side, and another end of each narrow tube portion located on the main tube portion side such that a gap is formed between each narrow tube portion and each electrode, and a length of each electrode is in a range of (0.041P+0.5) mm to (0.041P+8.0) mm inclusive, wherein “P” represents a lamp power in W, and the lamp power is 70 W to 400 W inclusive.