Abstract: The present invention provides an improvement in a cathode-ray tube that includes a rectangular faceplate having two long sides and two short sides wherein the ratio of the length of the long sides to the length of the short sides is approximately 16 to 9. The tube includes a major axis which parallels the two long sides and a minor axis which parallels the two short sides. The improvement comprises the ratio of the equivalent radius of the faceplate curvature along the major axis to the equivalent radius of the faceplate curvature along the minor axis being in the approximate range of 1.5 to 1.6, the ratio of the equivalent radius of the faceplate curvature along the long sides of the faceplate to the equivalent radius of faceplate curvature along the major axis being in the approximate range of 1.12 to 1.

Abstract: Disclosed are a method for the fabrication of a color television tube as well as a front panel for trichromatic television tubes. The disclosure can be applied to the reception of high-definition television transmissions. According to the disclosure, the front panels designed for a high-definition television tube screen are elements of the group of surfaces defined byZ=.SIGMA.(C(i).multidot.x.sup.j(i) .multidot.y.sup.k(i)Z(i)=Co(i).multidot.F.sup.-(j(i)+k(i)-1)100.multidot.ABS(Zn-Z)<5.multidot.Zdwhere Z is the dimension of a surface of the group, Zn the dimension of a test surface and Zd the dimension of the maximum value of the dimension of the surface. Co corresponds to a reference surface of the group.

Abstract: A method for the mounting of a shadow mask in a trichromatic cathode tube pertains especially to the mounting of the mask on a frame. The shadow mask has a perforated, plane active surface which must be held under sufficient mechanical tension, so that it preserves its planarity during the functioning of the tube. The method consists in increasing the dimensions of the active surface, either by heating it to expand it or by stretching it mechanically to give it the desired mechanical tension, and then in soldering the mask to a sufficiently rigid frame to maintain the active surface in its state of mechanical tension.