Abstract: An electron gun cathode structure includes a support member made of an insulating material, a first grid fixed to the support member, and a cathode disposed on the side of the support member opposite to the first grid. A thermal expansion .DELTA.L.sub.S /L.sub.S of the insulating material constituting the support member due to heat from the cathode is larger than a thermal expansion .DELTA.L.sub.G /L.sub.G of a material constituting the first grid due to heat from the cathode. A manufacturing method of an electron gun cathode structure includes preparing a member including a first face and a second face having a step therebetween, a height of the step being equal to a predetermined distance d.sub.12, placing a first grid on the first face, placing a spacer on the second face, placing an insulating support member on the first grid and the spacer, and grinding a top surface of the spacer opposite to its surface that is fixed to the support member so that an actual distance d.sub.12 becomes a desired value.

Abstract: An electron gun cathode structure includes a support member made of an insulating material, a first grid fixed to the support member, and a cathode disposed on the side of the support member opposite to the first grid. A thermal expansion .DELTA.L.sub.s /L.sub.s of the insulating material constituting the support member due to heat from the cathode is larger than a thermal expansion .DELTA.L.sub.G /L.sub.G of a material constituting the first grid due to heat from the cathode. A manufacturing method of an electron gun cathode structure includes preparing a member including a first face and a second face having a step therebetween, a height of the step being equal to a predetermined distance d.sub.12, placing a first grid on the first face, placing a spacer on the second face, placing an insulating support member on the first grid and the spacer, and grinding a top surface of the spacer opposite to its surface that is fixed to the support member so that an actual distance d.sub.12 becomes a desired value.

Abstract: In a cathode assembly of a cathode ray tube, a cathode having an emitter is inserted in a through-hole formed in an insulator. The emitter is provided so as to face a cylindrical electrode of a first grid at a predetermined distance. A hole communicating with the through-hole is formed at a longitudinal side of the insulator, and a tubularly rising shelter is provided between the emitter in the through-hole of the insulator and the hole. This satisfies (E.times.B)-(C.times.E)+(C.times.D)-(A.times.D).gtoreq.A. D, where the height of the hole is A, the height of the shelter is B, the length from the lower end of the shelter to the head of the cathode is C, the length between the cathode and the shelter is D, and the length between the cathode and the insulator is E. The cathode assembly prevents metal vapor, such as barium oxide of the cathode and nickel or chromium of the sleeve, from spreading through the hole of the insulator.