Patent ID: 6876138

Claim:
A color cathode ray tube comprising: a panel having an internal fluorescent surface; a funnel coupled to the panel and sealed in vacuum; a shadow mask for making the electron beam from the electron gun land on a certain portion of the fluorescent surface; a frame for fixing/supporting the shadow mask; a spring combining the frame assembly with the panel; an inner shield installed to a certain side of the frame from the panel side to the funnel side in order to protect the cathode ray tube against an external earth magnetic field; an electron gun placed at the inner surface of a neck portion of the funnel and generating an electron beam; a deflection yoke placed at the outer surface of the neck portion of the funnel and deflecting the electron beam from the electron gun toward a certain direction; and a CPM (convergence & purity magnet) for adjusting precisely the deflection direction of the electron beam and a reinforcing band installed to the outer circumference at which the panel is combined with the funnel in order to protect the panel and the funnel from an air atmosphere and external impacts; wherein a cross sectional shape of the yoke portion is quadrangular at which a corner portion has a radius of curvature that satisfies Rdi/Rdo>0.775 when an outer radius of curvature at the corner portion is Rdo and an inner radius of curvature at the corner portion is Rdi; wherein an angle of a straight line connecting a diagonal angle effective surface end to a cross point of a reference line on the tube axis is 50˜70° with respect to the tube axis when the reference line is defined as an imaginary line passing through a deflection center of the deflection yoke and perpendicular to the tube axis; and wherein the color cathode ray tube satisfies 7(mm)<Rdo<13(mm).