Patent ID: 6091189
Filing Date: 2000-07-18
Classification: H01J

Abstract:
An indirectly heated cathode for an electron tube comprising:a base body having nickel as a major component and including at least one kind of reducing agent;a metal member in a layer-like shape, said metal member having as a major component a metal provided with a reducing power equivalent to or smaller than a reducing power of the at least one kind of reducing agents included in the base body and larger than a reducing power of nickel and said metal member being formed on faces of the base body;an electron emitting substance layer formed by depositing alkaline earth metal oxides including barium on the metal member;wherein the metal member is formed on the faces of the base body such that the base body is restrained from deforming by thermal stresses of intermetallic compounds formed from diffusion of metals between the base body and the metal members on the faces thereof at portions of the base body bounded with the metal member, said reducing agent in said base body forming an interface between said metal member and said electron emitting substance layer which reacts with said alkaline earth metal oxides to further reduce a portion of the alkaline earth metal oxides and form an oxygen depletion-type semiconductor, thereby facilitating the emission of electrons.