POWER SUPPLY CIRCUIT FOR ALTERING FLICKERING FREQUENCY OF LIGHT-EMITTING DIODE

摘要

The present invention relates to a power supply circuit, and more particularly to a power supply circuit for increasing the flickering frequency of a light-emitting diode by means of a charging/discharging circuit and a switch connected between an alternating voltage source and a load. A power supply circuit according to the present invention includes: a rectifying circuit connected to the alternating voltage source for full-wave rectifying the alternating voltage thereof; a charging/discharging circuit with one end connected to the output terminal of the rectifying circuit and a light-emitting diode array and the other end to ground so as to be charged with the output voltage of the rectifying circuit and to supply power to the light-emitting diode array; a first switch arranged in the path connecting the charging/discharging circuit and the light-emitting diode array; and a controller for controlling the first switch so as to enable the charging/discharging circuit to discharge in the interval A less than the drive voltage of the light-emitting diode array, thus causing the light-emitting diode array to flicker at least one time in the interval A. The power supply circuit according the present invention can apply by means of the charging/discharging circuit and the switch a voltage of pulse-type equal to or greater than the drive voltage to the peripheral regions of a phase of 180 degrees where the voltage supplied from the alternating voltage source is equal to or less than the drive voltage and so cannot drive the light-emitting diodes. Thus, the invention can increase the flickering frequency of the light-emitting diode to more than 240Hz (when the alternating voltage source is 60Hz).