| 摘要 |
PURPOSE: A structure for preventing a howling of a shadow mask in a CRT(Cathode Ray Tube) is provided to improve the howling characteristic in an edge of the shadow mask by horizontally extending a folded portion via left/right corners of the shadow mask. CONSTITUTION: A folded portion(29) as a howling preventing member is formed via a section of a non-valid face(28) in a shadow mask(25). The intensity of left/right corners in the non-valid face(29) is increased. A natural frequency of the left/right corners becomes higher than a natural frequency of the shadow mask(25). Vibrations between the shadow mask(25) and the howling preventing member(29) are offset by the different frequencies. Thereby, the vibration is reduced.
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