| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-efficiency light-emitting diode constant-current drive circuit capable of attaining significant reductions in cost, size and weight, as well as, restraining an increase in power consumption, even if there is dispersion in the power supply voltage or the forward voltage drop in the light-emitting diode is fluctuated, and adjusting the luminance, without having to change the emission wavelength of the light-emitting diode. SOLUTION: The light-emitting diode constant-current drive circuit includes a transformer 4 having a primary and a secondary windings; a switching element 5 connected to the primary winding in series; an on/off control circuit 16 for on/off controlling the switching element 5; and a series connection circuit constituted of the diode 6, the constant-current element 15, and the light-emitting diode 12. A DC voltage (voltage of the capacitor 3) is added between the primary winding 4 and the switching element 5. COPYRIGHT: (C)2007,JPO&INPIT |
