Method of operating a positive tolerance crt

Abstract

A method of operating a positive tolerance color cathode-ray tube (CRT) having an evacuated envelope with an electron gun and a focus mask therein for generating at least one electron beam. The envelope further includes a faceplate panel having a luminescent screen of color-emitting phosphor stripes on an interior surface thereof. The color-emitting phosphor stripes each have a width slightly smaller than one-third of the screen pitch, such that large clipping and leaving tolerances may be achieved therewith. The focus mask, having a plurality of spaced-apart first conductive electrodes, is located adjacent to an effective picture area of the screen. The spacing between the first conductive electrodes defines a plurality of slots substantially parallel to the color-emitting phosphor stripes on the screen. Each of the first conductive electrodes has a substantially continuous insulating material layer formed on a screen facing side thereof. A plurality of second conductive electrodes (wires) are oriented substantially perpendicular to the plurality of first conductive electrodes and are bonded thereto by the insulating material layer. The method includes directing electron beams toward the color-emitting phosphors on the screen and applying an appropriate differential voltage to the two sets of conductive electrodes to achieve desired clipping and leaving tolerances of the CRT tube.