| 摘要 |
PURPOSE:To aim at the compensation of reduction in a luminescent spot cut-off voltage with consumption of an electron emission material, by forming a base metal into a three-layer structure. CONSTITUTION:A base metal 22 is constituted of a diffused layer (intermediate layer) 11 and two layers (surface layers) 22a and 22b sandwiching the former. In the operation of a cathode body structure for hours, movements of atoms from the diffused layer 11 to these upper and lower surface layers 22a and 22b occurs there. This atomic movement occurs uniformly in these upper and lower layers in a flat part where the base metal does not receive any stress of bending or the like, but at the bending part shaped in cap like, a diffused part 13 of high density is formed at the inside of the bending shape, and another diffused part 12 of low density is relatively formed at the outside of the bending shape, respectively. In consequence, stress occurs in the cap like pant of the base metal in a direction widening a bending angle of the bending part, and it is deformed so as to become a convex to the side of a first grid G1. With this constitution, luminance deterioration is small, thus such a cathode-ray tube that is excellent in a life characteristic is obtained.
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