| 摘要 |
PROBLEM TO BE SOLVED: To provide an illumination system detecting luminance of an illuminated object by a luminance sensor and performing light dimming control of an LED illumination fixture based on the detected value, in which the luminance detection is performed accurately as well as quickly to realize high accuracy and speed in feedback controlling of the LED illumination fixture. SOLUTION: A controlling part 4 of the illumination system 1 performs detection by a luminance sensor 3 when a lighting up voltage of a rectangular wave impressed on an LED 21 is On, and the sensor voltage value at that time is multiplied by the then duty cycle to obtain a present luminance, and based on the luminance, a feedback controlling on the duty cycle of the rectangular wave of the current supplied to the LED 21 is performed. As a result, even if the detected time is shorter than the On time of the lighting up voltage, for instance, the luminance can be detected accurately without an effect of the detected time. Further, detection of luminance once in one cycle of the lighting up voltage is enough, and the detection can be speeded up. COPYRIGHT: (C)2010,JPO&INPIT |
