| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress flickering of LED. <P>SOLUTION: A TRIAC dimmer 12 gates an AC waveform from an AC power source in proportion to a control signal and outputs a TRIAC pulse with part of the waveform missing. The TRIAC pulse is applied to a full-wave rectification LED array 16 and a drive current flowing to the LED array 16 is detected at a current detection resistor 22. The drive current value and a predetermined value are compared at a comparator 26 and in accordance with the comparison result thereof the control transistor is turned off. Then, the TRIAC pulse is converted to a DC voltage signal and in accordance with the obtained DC voltage signal, the drive current value or the predetermined value inputted by the comparator 26 is changed. Furthermore, instead of the TRIAC pulse, a PWM pulse supplied from an external source may also be utilized. <P>COPYRIGHT: (C)2013,JPO&INPIT |
