| 摘要 |
PURPOSE:To improve the color characteristic reproduction characteristic by employing a bymetal composed of a low thermal capacity member and a high thermal capacity member for the securing of a shadow mask and a mask frame thus performing the temperature compensation of the thermal expansion of the shadow mask in the entire operational region of a picture tube thereby eliminating the shift of position between an electron beam pass hole and a phosphor material dot. CONSTITUTION:A bymetal 49 is welded 52, 53 between the outer wall of a mask frame 44 and the inner wall of a shadow mask cart 43 where said bymetal 49 is composed of a low capacity bymetal 47 employing high expansion members 471, 482 and a high capacity bymetal material employing low expansion members 472, 482 and having the height (h) in the tube axial direction Z-Z'. In combination of the variation of the bymetal member 47 in the arrow direction 54 immediately after the function of the picture tube, the variation of the bymetal member 48 in the arrow direction 55 after elapsing some time and the height (h) in the tube axial direction Z-Z', the mask frame will vary in the arrow direction 56. Consequently the shift of position between the electron beam pass hole and the phosphor material dot is eliminated resulting in the improvement of the color purity characteristic of the picture tube. |
