Patent ID: 7355353
Filing Date: 2008-04-08
Classification: H05B,Y02B

Abstract:
1. An illumination control circuit for driving and controlling a light emission element, said circuit comprising: a generating device for generating a control signal of DC voltage for setting a brightness of the light emission element; a driving transistor connected in series with the light emission element and a power supply, for supplying a driving electric power from the power supply to the light emission element in accordance with said control signal, thereby causing the light emission element to emit a light; a detecting device for detecting a differential voltage between a power source voltage of the power supply and a predetermined reference voltage, dividing the differential voltage with an adjustable coefficient, thereby generating a detection voltage; and a compensation device connected in series with the light emission element and the driving transistor as well as the power supply, for power-amplifying the detection voltage and generating a compensation voltage which follows the detection voltage, thereby generating a differential voltage between the power source voltage of the power supply and the compensation voltage, between tow ends of the light emission element and the driving transistor, wherein when there is a change in the power source voltage of the power supply, the compensation device generates a compensation voltage, so as to make a changing rate of the differential voltage applied between tow ends of the light emission element and the driving transistor, to become smaller than a changing rate of the power source voltage which has involved a change.