Patent ID: 7218047
Filing Date: 2007-05-15
Classification: H01J

Abstract:
1. An indirectly heated electrode for gas discharge tube comprising: a coil member, wound in coil form; a heater, disposed at the inner side of said coil member and having an electrical insulating layer formed on a surface thereof; a metal oxide, serving as a material likely to emit electrons and held by said coil member; and an electrical conductor, having a predetermined length and disposed at the inner side of said coil member so as to be in contact with said coil member, wherein said metal oxide contacts said heater via said electrical insulating layer, and wherein said coil member is a multiple coil arranged by winding a coil having a mandrel in coil form, the mandrel having a cross section and the coil member being wound contiguously about the mandrel so as to define an inside shape that corresponds to the cross section of the mandrel.