Cathode ray tube

Abstract

A Cathode Ray Tube (hereinafter, CRT), includes a mask assembly which is composed of a main frame for supporting the shadow mask and a sub frame for supporting the main frame. When the minimum distance between the flat surface extended from the upper surface of the main frame and the flat surface extended from the lower surface of the sub frame is Lb, the height of the sub frame is Ls and the minimum distance between the flat surface extended from the upper surface of the main frame and the flat surface extended from the lower surface of the sub frame, in case the mask is attached to the mask assembly, is La, the following equation, 0.40≦Ls/Lb≦0.55 or 0.45≦(Ls−Lm)/Lb≦0.59 is satisfied and after compression, the following equation, 0.08≦(La−Lb)/(Lb-Lm)≦0.17 is satisfied. Therefore, the creep phenomenon, causing tension degradation and wrinkles at the corner portion of the shadow mask after the heat processing, can be prevented and the howling phenomenon, which can cause serious degradation of quality of screens by vibration of the CRT, can be prevented, considering the instrumental formality with a panel at the same time.

Dependencies are inferred from the claim text.