An improved shadow-mask design for in-line three-beam color picture tubes

Abstract

In a color picture tube using an in-line arrangement of three beams and the conventional shadow mask, the transmission of the shadow mask must be made very low in the corner regions in order to avoid the overlapping of adjacent in-line trios of landed beam dots on the screen. An improved design of aperture alignment on a shadow mask was developed for the in-line three beams in order to avoid this overlapping without reducing the transmission. In this new shadow mask, the apertures are aligned not along straight lines as in the conventional shadow mask but along certain curved lines. The horizontal aperture alignment curves are a barrel-shaped group of arcs of ellipses, and the vertical aperture alignment curves are a pin-cushioned group of arcs of circles. Brightness and color purity of the picture in the corner regions of the screen were much improved by using this shadow mask.