PURPOSE: To aim at improvement of the withstand voltage characteristics through increasing the charge up suppressing effect by providing an insulating film, which has the surface resistivity within a specific range and the secondary electron emission ratio of a value less than 1, on the internal surface of a neck in the fannel section.
CONSTITUTION: On the internal surface of a neck 3 is provided a Cr2O3 film 7, in which the film thickness is regulated so that the surface resistivity is 1012W1014Ω/opening, and the secondary electron emission ratio is less than 1. Thereby, the secondary electrons are not emitted in the number of electrons more than that of electrons which are produced by the field emission and the like from each of the electrodes 1aW1f of an electron gun 1 and made incident upon the film 7, and it is prevented that the tube wall of the neck 3 becomes positively charged. In addition, even if the internal surface of the neck 3 becomes negatively charged, the negative charge up can also be prevented in such a way as causing a negative electric charge to flow by means of the surface resistance into an internal conductive film 4. Accordingly, the withstand voltage characteristics can be improved.
IMANISHI WATARU
FUJII HARUHISA
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