Patent ID: 6873107

Claim:
A gas discharge tube which is caused to discharge a predetermined light toward the outside from a light exit window of a hermetically sealed container by sealing gas into said hermetically sealed container, electrically connecting an anode portion and a cathode portion respectively to first and second stem pins disposed in a standing position in a stem which is provided in said hermetically sealed container so as to extend in a tube axis direction, and generating discharge between said anode portion and said cathode portion, said gas discharge tube in comprising: a first discharge path limiting portion disposed at a point on a discharge path between said anode portion and said cathode portion and having a first opening for narrowing said discharge path; a second discharge path limiting portion disposed at a point on said discharge path between said first discharge path limiting portion and said anode portion and having a second opening for narrowing said discharge path; a first electrical insulation portion disposed between said first discharge path limiting portion and said second discharge path limiting portion; a third stem pin disposed in a standing position in said stem so as to extend in said tube axis direction, the distal end part of which is electrically connected to said first discharge path limiting portion; a fourth stem pin disposed in a standing position in said stem so as to extend in said tube axis direction, the distal end part of which is electrically connected to said second discharge path limiting portion; and a light-emitting portion assembly which houses said anode portion, said cathode portion, said first discharge path limiting portion, and said second discharge path limiting portion, and which is supported by said first through fourth stem pins, wherein a connecting portion between said second discharge path limiting portion and said fourth stem pin is surrounded by an insulator including said first insulating portion.