| 摘要 |
PROBLEM TO BE SOLVED: To suppress temperature rise in an electronic component of a power supply device by appropriately controlling power to be supplied to a light source.SOLUTION: An illuminating device 10 comprises a power supply device in which a circuit board 40 is housed. On the circuit board 40, a thermistor 45 detecting an ambient temperature, a buck converter 44 supplying power to a light source substrate 20 to lighten an LED 21, and a control circuit 46 controlling the power supplied from the buck converter 44 to the light source substrate 20 depending on the temperature detected by the thermistor 45, are mounted. The thermistor 45 is arranged at a position apart from an end part at a distant side from the light source substrate 20, of both end parts of the circuit board 40 by a distance 0.25 times or more and 0.55 times or less of a distance between both end parts. |
