A device for controlling the level of light in an area or room. The device includes a sensor that detects whether the room is occupied, a light meter that detects the level of ambient light entering the room, and circuitry that controls the lights in the room in response to the sensor and light meter....http://www.google.com.tw/patents/US5406173?utm_source=gb-gplus-share專利 US5406173 - Apparatus and method for adjusting lights according to the level of ambient light
