Cathode ray tube having an improved indirectly heated cathode structure

摘要

A cathode ray tube has an indirectly heated cathode structure including a base metal (3) having an electron emissive material coating (4) on an outer top surface thereof; a metal sleeve (2) having the base metal attached to an end of the metal sleeve; a heater (5) housed partly within the metal sleeve which includes a major heating portion (5f) formed of a spirally wound heating wire and leg portions (5g) formed of heating wires wound spirally in a plurality of layers; an insulating film (5b) covering the major heating portion and a portion of each of the leg portions continuous with the major heating portion; and a black coating film (5c) covering a portion of the insulating film extending from the major heating portion toward each of the leg portions, the whole of the black coating film being housed within the metal sleeve.