| 摘要 |
PURPOSE:To keep of any drop in image quality due to dielectric breakdown, by installing a shallow groove, in proportion to a faceplate, on a glass surface lying between a faceplate back outer circumferential part and a faceplate back inner part, and raising up the extent of creeping dielectric strength. CONSTITUTION:A groove 9 is installed between a transparent conductive film 2, a photoconductive film 3 and indium 6 on a glass surface of the backside of a faceplate 1. With this, length running along the faceplate glass surface between the transparent conductive film 2, the photoconductive film 3 and the indium 6 is considerably extended longer. If depth of this groove 9 is deepened, a creeping distance is prolonged. However, if it is deepened too much or a corner form of the groove 9 is made into such one as being small in a radius of curvature, mechanical strength in the faceplate 1 has been lowered. Accordingly, it is desirable to be in a form as the groove 9 shown or so shown in illustration. With this constitution, tube discharge is hard to occur, thus a favorable regenerated image is securable.
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