1. ABSTRACTThis is a report on the development of a lamp system that will change the extent of the illuminated area in response to the steering angle.The optical performance of headlamp systems has been improved in response to increases in automobile performance and changes in traffic conditions. However, most of a driver's perception at night is visual so it is necessary to improve the driver's forward visibility at night in accordance with the increased performance of automobiles.The light distribution of current headlamps is designed mainly in consideration of straight forward vehicle movement so the area that a driver wants to see when making a turn is not necessarily sufficiently illuminated.In order to provide sufficient illumination for safe cornering, a headlamp system that changes the distribution of light in response to the steering angle with the use of microcomputer control has been developed.The present prototype can change the range of illumination by moving only the sub-reflector incorporated in the lamp unit and not the whole lamp.An actual test of the system with it mounted in automobiles showed that the system is highly effective in properly illuminating the expected path of movement of the vehicle.Koito is confident that this system can greatly contribute to the safety of night driving.The system consists of the following four units. The lamp unit with a built-in sub-reflector for changing the range of illumination. An actuator for motor-driving the sub-reflector. A control unit which calculates in real time the sub-reflector drive angle based on the Steering signal. A steering angle sensor which detects the steering angle and sends digital pulses as a steering signal.