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

The in-line arrangement of three electron beams allows much easier convergence than the delta arrangement. However, in a color picture tube with three in-line beams and the conventional shadow mask, the transmission of the shadow mask must be made very low in the corner region to aviod the overlapping of adjacent in-line triplets of beam spots. This overlapping is due to interference between the geometrical tilt pattern of the directions of the in-line triplets landing on a spherical phosphor screen and the rectilinear alignment of apertures of the conventional shadow mask used. The paper presents an improved design of the geometrical aperture alignment, through which the overlappings are prevented throughout the whole screen area, allowing high transmission of the shadow mask with resulting brightness improvement.