CATHODE FOR ELECTRONIC TUBE AND MANUFACTURE OF ELECTRON GUN

摘要

PROBLEM TO BE SOLVED: To reduce variations in cut-off voltage by specifying an upper limit of the thickness of an electron-emission substance layer, in the case of a cathode used in a cathode-ray tube. SOLUTION: A substrate 1 has nickel as a main constituent and contains a trace of reductant such as silicon and magnesium. An electron-emission substance layer 2 is formed on the substrate 1 and made of an alkaline earth metal oxide containing at least barium and additionally containing strontium and/or calcium. Nichrome, a heat resistant metal, is used for a cathode sleeve 3 serving to fix the substrate 1. The substrate 1 and the electron-emission substance layer 2 are heated by a heater 4. In a cathode 10, the thickness T of the electron-emission substance layer 2 is limited to 90μm or less.