| 摘要 |
PURPOSE:To prevent a lighting failure by raising automatically a voltage to a discharge start voltage of a cold cathode fluorescent lamp at every OFF/ON of a power source irrespective of a resistance value of variable resistor for light control, and returning it to a light modulation state after a prescribed period of time. CONSTITUTION:In a resistance 7 and a variable resistance 8 for constituting a first feedback 9 for executing light modulation of a cold cathode fluorescent tube 10, a second feedback circuit 14 consisting of a resistance 12 and a capacitor 13 is provided in parallel to the variable resistance 8. A resistance value of the resistance 12 is made smaller than a resistance value of the variable resistance 8 in advance, and when a power source is turned on, irrespective of a resistance value of the variable resistance 8, a discharge start voltage is supplied to the cold cathode fluorescent tube 10 by a second feedback 14, so as to return to a usual light modulation state by the resistance value of the variable resistance 8, after a prescribed time elapses after lighting. |
