JPS646347A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the purity drift due to the change of the outside environmental temperature by specifying the inner angle between the first face and the third face and the angle between the second face and the third face in the region surrounded by the first face-third face of a frame holder. CONSTITUTION:The inner angle between the first face and the third face is an acute angle theta1 and the angle between the second face and the third face is an obtuse angle in the region surrounded by the first face-third face of a frame holder, and the equation I is satisfied, where alphap, alpham, alphaf are thermal expansion coefficients of a panel 1, a shadow mask 3, and a frame 4 respectively and 4 is a half angle of the electron beam deflection angle. Even if the thermal expansion occurs on the panel 1, shadow mask 3, and frame 4, these panel 1, shadow mask 3, and frame 4 are relatively deformed so that an electron beam hits the preset position of a panel fluorescent screen. The occurrence of the purity drift can be thereby prevented even if the electron beam hits the shadow mask for a long time or the outside environment temperature is changed.