| 摘要 |
PROBLEM TO BE SOLVED: To avoid drive in a frequency band for infrared remote control equipment, and to reduce a use frequency in the vicinity of a permitted maximum frequency of a switching element.SOLUTION: A dimming lighting circuit 1 for a semiconductor light-emitting element 4 comprises: a DC conversion circuit 12 including an inductor T2 and a switching element Q2 connected with a DC power supply via the inductor T2; and a DC conversion circuit controller 14 for on-off controlling the switching element Q2 of the DC conversion circuit 12. The DC conversion circuit controller 14 selectively performs a first control for changing an output current of the DC conversion circuit 12 by changing a switching frequency, and a second control for changing a magnitude of a current outputted from the DC conversion circuit 12 by changing an ON time period while maintaining the switching frequency at a boundary and out of the frequency band for the infrared remote control equipment at such a dimming level that the switching frequency enters into the frequency band for the infrared remote control equipment if the requested dimming level is achieved by the first control. |
