| 摘要 |
PROBLEM TO BE SOLVED: To provide an LED luminous flux control device capable of controlling a luminous flux of an LED at a constant value with a high accuracy without using a sensor such as an optical sensor and a temperature sensor.SOLUTION: Characteristics between a time elapsed after power-on and an ambient temperature of a light source part 5 composed of an LED, in a predetermined illuminating device, are stored into a storage part 16. A control part 13 measures a forward voltage of the light source part 5 at power-on, obtains the ambient temperature at power-on from a known relation between the ambient temperature and the forward voltage, and obtains elapsed time-temperature characteristics in the case that the ambient temperature is set as an initial temperature, by correcting the characteristics stored in the storage part 16. Thereafter, the control part 13 obtains the current ambient temperature of the light source part 5 using the corrected elapsed time-temperature characteristics and the time elapsed from the power-on, and obtains a luminous flux value corresponding to a current ambient temperature using the known characteristics between the ambient temperature and the luminous flux, and repeats control so that the luminous flux emitted by the light source part 5 becomes a target value. |
