Patent ID: 6046540
Filing Date: 2000-04-04
Classification: H01J

Abstract:
A color picture tube comprising:a panel, an inner surface of which has an image display area; anda phosphor screen provided throughout the image display area on the inner surface of said panel, for displaying an image by being subject to irradiation of an electron beam; wherein:a Z-axis is superposed on a tube axis passing through a center of said panel and being normal to said panel;a direction from an inside of the color picture tube to a viewer is set to be a positive direction of the Z-axis;a radial distance from the Z-axis is denoted by r;a point at which the Z-axis intersects the inner surface of said panel is denoted by a point at which r=0;an outermost point in a diagonal direction of the image display area is denoted by a point at which r=L.sub.d ;a position of a point on the inner surface of said panel in a direction of the Z-axis is expressed by f(r) being a function of r;a value of df(r)/dr which is a first derivative of f(r) is zero in a first area within the image display area, which includes a point at which r=0, and is negative in a second area within the image display area from an outside of the first area to the point at which r=L.sub.d ;a value of d.sup.2 f(r)/dr.sup.2 which is a second derivative of f(r) is negative in a third area within the image display area from the point at which r=0 to an inside of a point at which r=R.sub.2 being within the second area, is zero at the point at which r=R.sub.2, and is positive in a fourth area within the image display surface from an outside of the point at which r=R.sub.2 to the point at which r=L.sub.d ; anda thickness (DR) of said panel in the second area in the direction of the Z-axis is larger than a thickness (T.sub.0) of said panel in the first area in the direction of the Z-axis.