| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting circuit capable of selecting an efficient lighting circuit according to a voltage range of a lighting power supply of a cold cathode discharge lamp. <P>SOLUTION: A comparator IC controlling Q4 controlling ON/OFF of a PWM-IC used for a current dimming system and Q3 changing a current on a primary side of a high voltage circuit is provided. Input voltage from two kinds of power supplies are compared with reference voltage, when the input voltage is lower than the specified value, it is determined as the battery power supply and the Q4 is cut, the PWM-IC is turned off and the Q3 is turned on, and the primary side of the high voltage circuit is grounded with the Q3 to activate as the efficient lighting circuit. The efficient lighting circuit and the circuit of the usual current dimming system are switched according to the power supply of the battery of two kinds of power supplies of the cold cathode discharge lamp and an AC adaptor so that it can bear for long-term use in the case of the battery. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
