| 摘要 |
PURPOSE:To save power and miniaturize a device by connecting a load current set changing circuit part to the feedback control system of a load setting element only at the time of lighting, and setting the load current of a cold cathode- ray tube to a minimum current value capable of holding the lighting. CONSTITUTION:At the time of lighting, a control signal is inputted to a signal input terminal S, a switching element PC is ON, and a load current set changing circuit part is connected to the feedback control system of load current setting elements R5-R7 and C3 to set the load current of a cold cathode-ray tube CCFT to a minimum current value capable of continuously holding the lighting. Thus, the load is minimized to allow the lighting at a low lighting starting voltage, and since the cold cathode-ray tube requires no high voltage when once lighted, a small size transformer and a circuit part having a low withstand voltage rated value can be used. Since the load current is small, further, the consumed power is greatly reduced. After the lapse of a determined time, this set is released and controlled to a load current capable of providing a determined luminance. |
