| 摘要 |
PURPOSE:To shorten a warm up period by heating a line cathode by using a warm up power source while emission amount from the line cathode is small. CONSTITUTION:Immediately after power is turned on, no power flows a vertical focus electrode 11 because a line cathode 2 is cool and is in a state of no emission; the output of a comparator 55 goes to H; a transistor 54a is turned on; and a transistor 54b is turned off. The power supply of the line cathode drive circuit 52 is connected to an initial heat power source 53 about 200% higher in voltage than a power source 50, then the line cathode 2 is heated rapidly. The line cathode 2 then starts emission to increase current flowing the electrode 11, and when the output of the comparator 55 goes to L, the transistor 54a is turned off and equally 54b turned on, returning to a normal action.
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