| 摘要 |
PURPOSE:To obtain a uniform beam from an end to another end of a cathode by heating a linear cathode by applying heating current during beam irradiation stop period and modulating the beam by impressing video signals during beam irradiation period. CONSTITUTION:Cathodes 10a, 10b... are linear long in vertical direction and made by coating an oxide cathode material on the surface of tungsten wires and plural number of them are arranged at equal spaces in horizontal direction. In a period when beam irradiation on a screen is stopped, switches 103a, 103b... are made off, switches 101a, 101b... and switches 102a, 102b... are made on, and cathodes 10a, 10b... are heated by applying current by a power source 105. In a period when beam is irradiated on the screen, switches 101a, 101b... and 102a, 102b... are made off, and switches 103a, 103b... are made on, and the beam irradiated from cathodes 10a, 10b... onto the screen is modulated by video signals by applying video signals outputted from video amplifiers 104a, 104b....
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