US Patent 7382086 Indirectly heated cathode and cathode ray tube having same

An indirectly heated cathode includes a cathode sleeve (2) housing a heater (1), a caplike base (3) attached onto the cathode sleeve (2), and an electron emitter layer (4) formed on a surface of the base (3). The cathode sleeve (2) is made of a metal material that contains nickel and chromium as main components and further contains at least silicon, aluminum, cerium, and lanthanum. According to this construction, the cathode sleeve (2) is kept from heat deformation. Hence a reliable indirectly heated cathode which suppresses variations in cutoff voltage can be realized.