Hitachi, Ltd.

Hitachi Metals, Ltd.

Ryoji Hirai

Akira Misumi

Rikizo Watanabe

Eiichi Yamazaki

Fumiaki Yonai

Hiroyuki Ikeda

Mitsuru Yoshizawa

Yuuichi Inoue

Curve surface shapes Z.sub.X, Z.sub.Y on the long axis and short axis of at least the outer surface of a face plate are approximated by Z.sub.X =A.sub.1 X.sup.2 +A.sub.2 X.sup.4 +A.sub.3 X.sup.6 and Z.sub.Y =A.sub.4 Y.sup.2 +A.sub.5 Y.sup.4 +A.sub.6 Y.sup.6, and the curved surface shapes P.sub.X, P.sub.Y of at least the outer surface of the face plate panel at points (X=X.sub.1, Y=Y.sub.1) of effective screen boundary portions are given by P.sub.X =A.sub.1 X.sub.1.sup.2 /(A.sub.1 X.sub.1.sup.2 +A.sub.2 X.sub.1.sup.4 +A.sub.3 X.sub.1.sup.6) and P.sub.Y =A.sub.4 Y.sub.1.sup.2 /(A.sub.4 Y.sub.1.sup.2 +A.sub.5 Y.sub.1.sup.4 +A.sub.6 Y.sub.1.sup.6), wherein 0.6&lt;P.sub.X .ltoreq.0.9 and 0.6.ltoreq.P.sub.Y .ltoreq.1.0 are satisfied. The curvature radii R (mm) of the effective screen boundary portion of the short side and long side satisfy the relationship: 2.0 (42.5 V+45.0)&lt;R.ltoreq.4.0 (42.5 V+45.0), where the effective diagonal diameter of the face plate panel is V (inches). This enables a flatter periphery, less distorted panel surface and less doming effect.

Color cathode ray tube of shadow mask type

A rectangular faceplate panel of a color picture tube of the shadow mask type. In the periphery of the rectangular faceplate panel, a curvature C.sub.PL at a long side peripheral portion is made larger than a curvature C.sub.PS at a short side peripheral portion by a value within a range of from 10% to 100%. Further, a level difference z of a diagonal axis of the rectangular faceplate panel is selected to be large and an average radius of curvature in the diagonal direction of the rectangular faceplate panel is selected to be small. Thus, in the color picture tube of the shadow mask type, the faceplate of can be made to look flat, the doming phenomenon can be improved, and sufficient mechanical strength of the glass envelope can be obtained.

Color picture tube with flat appearing face plate

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.

Color picture tube of shadow mask type with particular faceplate panel

A color picture tube shadow mask material is made of an alloy consisting of 30 to 45 wt. % of Ni, 0.1 to 5.0 wt. % of V, and the balance essentially Fe. A color picture tube having a shadow mask consisting of this material is also prepared. The alloy has an average thermal expansion coefficient of 6.times.10.sup.-6 /.degree.C. or less in a temperature range of 20 to 100.degree. C., and an elasticity coefficient of 15,000 kgf/mm.sup.2 or more.

Color picture tube shadow mask material

A color picture tube includes a shadow mask of a precipitation strengthening Fe-Ni alloy. The alloy contains Fe-Ni as a major constituent and has at least one additive element. The alloy has a precipitation strengthening phase of Ni.sub.x X.sub.y (wherein X is at least one element selected from the group consisting of Al, Ti, Nb, Ta and Zr; x is 2 to 4; and y is 0.05 to 1.5) and an average thermal expansion coefficient of not more than 6.times.10.sup.-6 /.degree. C. in a temperature range of 20.degree. C. to 100.degree. C.

Color picture tube with shadow mask

A color picture tube suited for use as a video data terminal equipment of a computer system and capable of displaying characters, graphs and the like with high fineness. In a shadow mask of dot aperture type to be used in the color picture tube, a space between the adjacent dot apertures aligned on a same line in the horizontal direction and a space between the adjacent dot aperture aligned on a same line in the vertical direction is selected equal to each other.

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Mobara, Japan

Ryoji Hirai