Improvements in or relating to the manufacture of cathode assemblies for electric discharge devices, especially cathode ray tubes

摘要

673,191. Discharge apparatus. GENERAL ELECTRIC CO., Ltd., and DUDLEY, M. D. Dec. 15, 1950 [Jan. 24, 1950], No. 1876/50. Class 39 (i). A method of manufacture of an electrode assembly, especially for a cathode-ray tube, wherein an indirectly-heated cathode 4 has the form of a hollow body having an aperture facing a co-operating electrode 2 and coated internally round the aperture with electron-emissive material so that the aperture is adapted to act as a virtual cathode, comprises the use of a spacer 16 against opposite sides of which the surface of the cathode containing the aperture and the surface of the co-operating electrode are brought into abutment, the spaces being subsequently withdrawn. In the Figure the co-operating electrode comprises a hollow cylinder 1 closed at one end by a flanged disc 2 having a central aperture. The cathode 4 comprises a metal tube open at both ends and coated internally for the whole of its length with emissive material; it is supported from a ceramic disc 5 attached to a metal cylinder 11 which is a push fit into the cylinder 1. Cylinders 1 and 11 have apertures 15, 14 through which the spacer 16 is inserted and withdrawn. In manufacture the cylinder 11 is pushed into the cylinder 1 until the spacer is sandwiched between the cathode and the disc 2 when the cylinder 11 is spot-welded to the cylinder 1 and the spacer then withdrawn.