Patent ID: 8922137
Filing Date: 2014-12-30
Classification: H05B,Y02B

Abstract:
1. A dimming control device to which an illuminance sensor and a light source are connected and which performs dimming control and lighting control on the light source, the dimming control device comprising: an average filter that outputs, as an average illuminance, an average value of illuminance information acquired in the illuminance sensor during a predetermined period; an illumination illuminance computation portion that determines an illumination illuminance an ambient illuminance computation portion that determines an ambient illuminance; a conversion rate reference portion that acquires the ambient illuminance, and that outputs a PWM (pulse width modulation) conversion rate based on a conversion rate table; a multiplication portion that acquires the PWM conversion rate and a PWM initial value, and that outputs a PWM setting value obtained by multiplying the PWM conversion rate and the PWM initial value; a signal generation portion that receives the PWM setting value, and that outputs a PWM signal for lighting the light source; and a light source lighting current source that performs intermittent pulse lighting control on the light source based on the PWM signal, wherein the illumination illuminance computation portion acquires a first average illuminance output from the average filter before the dimming control device lights the light source and a second average illuminance output from the average filter when the dimming control device lights the light source with a predetermined output, divides a differential illuminance obtained by subtracting the first average illuminance from the second average illuminance by a PWM setting value at a time of the acquisition of the second average illuminance so as to calcualte a variation rate of the illumination illuminance with respect to the PWM setting value and multiplies a current PWM duty ratio of the PWM signal by the variation rate so as to calculate the illumination illuminance, and wherein the ambient illuminance computation portion acquires the illumination illuminance from the illumination illuminance computation portion, and subtracts the illumination illuminance from the average illuminance so as to calculate the ambient illuminance.