| 摘要 |
PROBLEM TO BE SOLVED: To provide an electron gun structure and CRT with the built-in elec tron gun promising the higher picture resolution by suppressing unwanted elec tron radiation which were once seen when Ba and BaO coming from evaporation from the cathode electric pole adhered at the grid electric pole or at the surface of the first grid electric pole and the second grid electric pole and within the electron passing-hole, the adhered Ba and BaO were reduced by small volume of reducible impurities contained in the plate-shaped electric pole material consisting of the first and second grid electric poles to produce an abundant Ba, the unwanted electron radiation was created from the surrounding edge of an electron passing-hole by the abundant Ba and thus brought the deteriora tion of the picture resolution. SOLUTION: The unwanted electron radiation can be avoided by forming the inner wall part of an electron passing-hole 24 of the plate-shaped electric pole 25 making the first grid electric pole G1 with an electron passing-hole 24 at least and the insulation tunic 36 at the surface of the second grid G2 side in serial connection at the surrounding area of the said electron passing-hole 25 and by preventing Ba and BaO adhered at the first grid G1 and the reducible impurities of the plate-shaped electric pole 25 from being combined together.
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