A Three-Gun Shadow-Mask Color Kinescope

Abstract

A three-gun shadow-mask color kinescope is described as well as construction techniques. The beams, from three guns mounted together in a 2-inch diameter neck, are deflected by a single deflection yoke. The guns are pointed so that the electron beams converge to a spot on a thin, perforated metal sheet that acts as a mask and is located a short distance away from a viewing screen composed of many phosphor dots. Associated with each hole in the mask is a trio of phosphor dots capable of emitting the three primary colors, red, blue, and green. The dots are so placed that each electron beam as it scans can "see" only one dot of the trio. Each of the three beams is thus capable of exciting one color only, and when all three beams áre modulated with the appropriate primary color information, a picture in full color can be reproduced. An apparatus called the "lighthouse" is used to record the locations of the phosphor dots on a photographic plate placed behind the mask and in the plane of the phosphor screen. A point source of light, at the position from which the deflection of one of the beams appears to take place, is used to simulate the electron beam in recording the phosphor dot positions. The pattern for one color of phosphor is the same as for the other two colors, and the geometry of the hole system in the mask is such that the three phosphor patterns nest together perfectly.