| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply unit and a luminaire, capable of achieving stable dimming control. SOLUTION: Depending on the dimming depths k1, k2 to k7 of a dimming signal k, the power supply unit prepares a reference signal Vref1 varying between a signal value equivalent to the maximum current in full light and a signal value equivalent to the minimum current when a dimming depth is the deepest and a reference signal Vref2 varying between a signal value equivalent to the load voltage equivalent to the maximum current in full light and a signal value equivalent to the minimum current when the dimming depth is the deepest. In a region approximate to full light having a shallow dimming depth, the power supply unit selects the reference signal Vref1 to control light-emitting diodes 19-21 in constant current in a current control mode, and in a region where the dimming depth is deep, the power supply unit selects the reference signal Vref2 to control the light-emitting diodes 19-21 in constant current in the voltage control mode. COPYRIGHT: (C)2010,JPO&INPIT |
