| 摘要 |
PROBLEM TO BE SOLVED: To provide an LED drive circuit capable of being driven directly by an AC input, suppressing generation of flickers, and achieving low power consumption.SOLUTION: An LED drive circuit for an LED array 15 having a plurality of LEDs connected in series, comprises: a rectifier FR1 full-wave-rectifying an AC input; a constant current circuit 30A-30N having a plurality of driving transistors connected via a voltage dividing resistor 40B with an output group of an operational amplifier 40A from which a reference voltage is generated on the basis of an output of the rectifier FR1; and resistors of current detectors 50A-50N respectively inserted between emitters of the driving transistors. The LED drive circuit is configured so that one end at an output side of the rectifier FR1 is connected with an input side of the LED array 15, and one ends at an output side of the plurality of transistors are respectively connected with connection points 20A-20M with the different number of LED groups in the LED array 15, and the plurality of transistors selectively drive the LED array 15 depending on an AC input voltage, and also, a current of the selectively-driven LED array 15 is varied depending on the AC input voltage. |
