Patent ID: 7781975

Claim:
A gas discharge tube comprising: a sealed container in which a gas is sealed; an anode disposed within the sealed container; a cathode which is spaced from the anode in the sealed container and generates discharge between the cathode and the anode; and a conductive part restricting a discharge path, the conductive part being disposed between the anode and the cathode and narrowing the discharge path formed between the anode and the cathode; wherein the gas discharge tube further comprises a cathode cover made of ceramics having a cathode side cover portion which covers the cathode in a manner enabling the cathode to emit electrons, and an anode side cover portion which covers an assembly including the anode and the part restricting the discharge path in a manner enabling the assembly to discharge between the anode and the cathode, and said anode side cover portion has a flat upper portion wall having an opening and said upper portion wall is fixed to the assembly, wherein the gas discharge tube further comprises a base holding the anode, and a plate fixing the part restricting the discharge path, the plate being placed on the base, wherein the part restricting the discharge path is mounted on a cathode side face of the plate and is fixed and pressed by the back side of the flat upper portion wall of the cathode cover from an upper side of the part restricting the discharge path, and wherein the cathode cover is configured to surround both side walls of the plate and the base.