| 摘要 |
PROBLEM TO BE SOLVED: To adjust emission luminance by installing a bidirectional flyback transformer, having a semiconductor switch which has a reverse directional blocking characteristic and an inductor function, and generating an oscillating voltage satisfying a resonance condition at the time of flyback operation by controlling the exciting current energy of the transformer. SOLUTION: The threshold level of the terminal voltage of a resistor 82 is set by a variable resistor 81, the reference voltage value set by the variable resistor 81 is compared with the terminal voltage value of the resistor 82 in a control circuit 4, and the closing time of a semiconductor switch 51 or 52 is controlled by the magnitude of a value obtained by amplifying the difference voltage of the comparison. When the voltage between both the terminals of the resistor 82 is lower than the reference voltage set by the variable resistor 81, the excitation current of a transformer 31 is increased by making the closing time of the semiconductor switch 51 or 52 long and the current value flowing through a discharge tube 2 is increased by making the voltage after the opening operation period of the semiconductor switch 51 or 52 high, and thereby emission luminance is increased. Thus, the emission luminance is controlled by means of the variable resistor 81. |
