Cathode-ray tube having improved 16.times.9 aspect ratio faceplate

In a cathode-ray tube including a rectangular faceplate having two long sides and two short sides, the ratio of the length of said long sides to the length of said short sides being approximately 16 to 9, said tube including a major axis which parallels said two long sides and a minor axis which parallels said short sides, and said tube including a rectangular viewing screen on an inner surface thereof, the improvement comprising

• said faceplate having an inner surface contour defined by the equation,
• Z=C(1)X.sup.2 +C(2)X.sup.4 +C(3)Y.sup.2 +C(4)X.sup.4 Y.sup.2 +C(5)Y.sup.4
• where:
• Z is the distance from a plane tangent to the center of the inner surface contour,
• X and Y represent distances from the center in the directions of the major and minor axes, respectively,
• C(1) to C(5) are coefficients that depend on the diagonal dimension of the viewing screen on the faceplate.

In a cathode-ray tube including a rectangular faceplate having two long sides and two short sides, the ratio of the length of said long sides to the length of said short sides being approximately 16 to 9, said tube including a major axis which parallels said two long sides and a minor axis which parallels said short sides, and said tube including a rectangular viewing screen on an inner surface thereof, the improvement comprising

• said faceplate having an inner surface contour defined by the equation,
• Z=C'(1)X.sup.2 +C'(2)X.sup.4 +C'(3)Y.sup.2 +C'(4)X.sup.4 Y.sup.2 +C'(5)Y.sup.4
• where:
• Z is the distance from a plane tangent to the center of the inner surface contour,
• X and Y represent distances from the center in the directions of the major and minor axes, respectively,
• C'(1) to C'(5) are coefficients that depend on the diagonal dimension of the viewing screen on the faceplate and which are defined by the equation,
• C'(I)=K.SIGMA.C(I).lambda.F.sup.[J(I)+L(I)-1]
• where:
• F is a scale factor, equal to the viewing diagonal of the viewing screen of a tube, in cm, divided by 66 cm,
• K is a factor that changes the curvature of the inside surface contour of the faceplate,
• J(I) and L(I) are the respective powers of X and Y associated with the coefficients C(1) to C(5), and
• the coefficients C(1) to C(5) are approximately equal to
• ______________________________________ C(1) = 0.338678 .times. 10.sup.-03 C(2) = 0.629894 .times. 10.sup.-09 C(3) = 0.603681 .times. 10.sup.-03 C(4) = -0.222411 .times. 10.sup.-13 C(5) = 0.172513 .times. 10.sup.-09 ______________________________________
• where X and Y are in millimeters.

In a cathode-ray tube including a rectangular faceplate having two long sides and two short sides, the ratio of the length of said long sides to the length of said short sides being approximately 16 to 9, said tube including a major axis which parallels said two long sides and a minor axis which parallels said short sides, and said tube including a rectangular viewing screen on an inner surface thereof, the improvement comprising

• said faceplate having an inner surface contour defined by the equation,
• Z=.SIGMA..sub.I C(I).SIGMA.K/F.sup.J(I)+K(I)-1.SIGMA. X.sup.J(I).SIGMA. Y.sup.K(I)
• where:
• Z is the distance from a plane tangent to the center of the inner surface contour,
• X and Y represent distances from the center in the directions of the major and minor axes, respectively,
• C(1) to C(5) are coefficients that depend on the diagonal dimension of the viewing screen on the faceplate,
• F is a scale factor equal to the viewing diagonal of the viewing screen of a tube, in cm, divided by 66 cm,
• K is a factor that changes the curvature of the inside surface contour of the faceplate,
• J(I) and L(I) are the respective powers of X and Y associated with the coefficients C(1) to C(5).