| 摘要 |
PROBLEM TO BE SOLVED: To control turn-on of three pieces of cold cathode tubes with a single inverter, to remarkably reduce the cost and to miniaturize a back-light by combining/controlling both of an output of the inverter and switching of a semiconductor switch serially connected to the cold cathode tubes. SOLUTION: A switch 2 controlling the power source of the inverter 3 in a high voltage generation means 4 is provided in addition to switch means 8, 9 and 10 consisting of a bi-directional thyristor respectively serially connected to the cold cathode tubes 5, 6 and 7, and by combining/controlling these switch 2 and switch means 8, 9 and 10, the electric discharges of the cold cathode tubes 5, 6 and 7 are stably controlled. When the cold cathode tubes 5, 6 and 7 are intended not to be electrically discharged, the switch 2 constituting the high voltage generation means 4 is made in an OFF state, and by bringing the output voltage of the inverter 3 to <= a discharge start voltage, the electric discharges of all cold cathode tubes 5, 6 and 7 are stopped. |
