| 摘要 |
PROBLEM TO BE SOLVED: To eliminate excess of a filament current and an emission current over their set points. SOLUTION: This filament lighting power circuit is provided with an automatic control circuit with two controls of an internal loop and an external loop. The internal loop is constituted of a filament 3, a filament current monitor 4 and a filament lighting circuit 2. Outside it, the external loop is constituted of a filament 3, an emission current monitor 5, a microcomputer CPU 1 and a filament lighting circuit 2. The filament current monitor 4 monitors a filament current and feeds back to its lighting circuit 2 whereby the filament current is controlled to a certain set point. At the same time, the emission current monitor 5 monitors an emission current and the microcomputer CPU 1 controls the emission current constant. |
