Method of installing a color selection electrode in a color cathode ray

Abstract

This disclosure depicts a method useful in the manufacture of a color cathode ray tube of the type having a phosphor screen and spaced therefrom a tensed color selection electrode. The method is a method of installing the electrode such that under normal tube operating conditions, the electrode is held by a holder in a hypertensed state and is thus capable of withstanding an unusually high electron beam bombardment before relaxing. In a preferred execution the method comprises selecting for the electrode a material which has a significantly higher coefficient of thermal expansion than that of the holder. The electrode and the holder are externally heated together, as by an oven, while the electrode is tensed. Simultaneously therewith, a selective auxiliary heating of the electrode is expected, as by passing an electrical current through the electrode, or by RF heating, such that the holder is heated to a predetermined first elevated temperature significantly greater than the first temperature, the holder and electrode thus being caused to thermally expand, but the electrode by a greater amount. The electrode is affixed to the holder. Finally, the electrode and holder are cooled to room temperature so as to hypertense the electrode due to the greater coefficient of thermal expansion and temperature fall of the electrode than the holder.