| 摘要 |
1,264,575. Cathode-ray display tubes. MATSUSHITA ELECTRONICS CORP. 20 April, 1970 [24 April, 1969 (2)], No. 18761/70. Heading H1D. The focusing lens of a cathode-ray display tube comprises at least five apertured metal plates 8, Fig. 1, connected alternately to high and low potentials to produce a periodic electric field and arranged between a first accelerating electrode 4 and a fluorescent screen 6. In Fig. 1 the even-numbered plates are connected together to the wall coating 11 and to the potential E 2 whilst the odd-numbered plates are connected to the potential E 1 where E 2 >E 1 #0À2E 2 and E 2 is between 5 and 30 kV. The plates may be circular discs of radius r 2 having apertures of radiusr 1 and a spacing d; preferably d#2 r 1 and also d#r 2 - r 1 . The thickness of the discs may be about 0À8 mm. or less. In a modification (Figs 4 and 5, not shown), there are seven discs of which the odd-numbered ones have apertures of radius r 3 and are connected to a high potential and the even-numbered ones have apertures of a larger radius r 4 and are connected to a low potential. The spacing d may be equal to r 3 and r 4 may be twice r 3 . |
