| 摘要 |
<p>PROBLEM TO BE SOLVED: To achieve a low-noise power supply circuit for LED illumination that can be used safely even in a medical site.SOLUTION: An LED illumination power supply circuit 10 comprises: a diode bridge rectification circuit 14 rectifying an AC current supplied from an AC power supply 12; and a smoothing capacitor 16 smoothing a DC current obtained by rectifying by the diode bridge rectification circuit 14. An LED load 20 is supplied with the DC current obtained by rectifying and smoothing by the diode bridge rectification circuit 14 and the smoothing capacitor 16, and is driven to emit light. The power supply circuit for LED illumination 10 is configured by insertion-connecting first to fourth current limiting circuits 26, 28, 30, 32 connected in parallel, between the AC power supply 12 and the diode bridge rectification circuit 14. The current limiting circuits 26, 28, 30, 32 are configured by comprising multilayer ceramic capacitors 44a-44d, respectively. The current limiting circuits 26, 28, 30, 32 having electrostatic capacitances different from each other, and are provided with control switches 34a, 34b, 34c, 34d individually controlling turn-on and turn-off of the current limiting circuits 26, 28, 30, 32.</p> |
