TENSIONED DIRECTLY HEATED CATHODE HAVING IMPROVED TEMPERATURE CHARACTERISTICS

1,216,584. Cathode-ray tubes. SYLVANIA ELECTRIC PRODUCTS Inc. 29 Jan., 1968 [1 Feb., 1967], No. 4548/68. Heading H1D. A directly heated cathode 13 which is freely suspended in an electron gun for a C.R.T. comprises a circular planar central portion 14 with an electron emissive coating 15 on one face, a first reduced width portion 16 extending radially from the central portion 14 to a first support 27 to provide a first electrical connection to the cathode, and a second similar reduced width portion 161 extending, diametrically opposite the first portion 16, from the central portion 14 to second support 271 to provide a second electrical connection. Both reduced width portions 16 and 161 have similar cross-sections such that they provide sufficient resistance heating and thermal isolation for the cathode. The cathode is preferably secured by enlarged portions 17, 171 at the end of reduced portions 16, 161 to supports 27, 271 by the suspension arrangement described in Specification 1,216,583. The central portion 14 of the cathode is preferably of larger diameter than aperture 25 in associated electrode 23 of the electron gun. Specific dimensions of an example are given.