Patent ID: 7301282

Claim:
A high pressure mercury lamp comprising: a light-emitting vessel having a main portion and an end portion, both the main portion and the end portion being made of quartz, the main portion enclosing a first space, the end portion enclosing a second space in communication with the first space, a conductive sealing plug member inserted in the second space and fixed in said end portion and electrically connected to said end portion, the conductive sealing plug member having an inner end and an outer end, the inner end of the conductive sealing plug member being exposed to the first space, an electrode member contained in said vessel and attached to the inner end of the conductive sealing plug member, and a power supply member attached to the outer end of the conductive sealing plug member, wherein said conductive sealing plug member is press sealed in said end portion, the end portion is softened and press sealed against the plug member upon heating, a side wall surface of the conductive sealing plug member is pressured into direct contact with an inner wall surface of the end portion, said conductive sealing plug member is composed of a sintered body made from silica granules each having a coating of at least one of a metal and a compound of a metal, and said sintered body comprises a conductive network structure made of said metal and having a content of said metal of not higher than 20 volume percent, wherein said conductive sealing plug member has a part substantially having a shape of a body of rotation formed by rotating a figure around the central axis of said vessel, and wherein the side wall surface of the conductive sealing plug member is pressed over the whole of the inner wall surface of the end portion radially toward the central axis of said-vessel.