Color picture tube of shadow mask type with particular faceplate panel

Abstract

A color picture tube of shadow mask type includes a faceplate panel mounted on the tube. The faceplate panel has curvatures along its major and minor axes, respectively. When the outer surface contour of the faceplate panel is represented by a three-dimensional expression in the orthogonal coordinate system defined by the X-axis corresponding to the major axis, the Y-axis corresponding to minor axis, and the Z-axis corresponding to the axis of the tube, respectively, curved contours Z.sub.x and Z.sub.y of the faceplate panel along the major axis and the minor axis are so realized as to be approximated by Z.sub.x A.sub.1 X.sup.2 +A.sub.2 X.sup.4 and Z.sub.y =A.sub.3 Y.sup.2 +A.sub.4 Y.sup.4, respecvtively, where X and Y represent distances from the center of the faceplate panel along the X-axis and the Y-axis, respectively, and wherein the constants A.sub.1, A.sub.2, A.sub.3 and A.sub.4 are so selected that the conditions that 0.3.ltoreq.P.sub.x (X=X.sub.1).ltoreq.0.6 and 0.95.ltoreq.P.sub.y (Y=Y.sub.2).ltoreq.1.0 where P.sub.x =A.sub.1 X.sup.2 /(A.sub.1 X.sup.2 +A.sub.2 X.sup.4), P.sub.y =A.sub.3 Y.sup.2 /(A.sub.3 Y.sup.2 +A.sub.4 Y.sup.4) are satisfied at points X.sub.1 and Y.sub.2 on the boundaries defining an effective picture area on the faceplate. Further, the contours of the effective picture area defining boundaries extending in parallel with short and long sides of the outer surface of the faceplate panel are so curved as to have approximately equal curvature, the radius R (mm) of which on the boundary is so selected as to satisfy the condition that 1.5 (42.5 V+45.0).ltoreq.R.ltoreq.2.0 (42.5 V+45.0), where V represents the diagonal length of the effective picture area.