Abstract: An apparatus for and a method of preventing a car from coming into collision with an object car running ahead or behind, by monitoring car running conditions in the front and rear of the car by the provision of front and rear sensors to give an alarm to the front and rear object cars when an emergency situation has monitored, sensing a slope of a road surface on which the car runs to remove an error caused by an inclination of the car, sensing a handle rotation of the car to enable the car to follow the front object car on a curved road and to be informed of situations in the front and rear of the car on the curved road, establishing a sufficient safety distance, and sensing an emergency situation occurring in the rear of the car to inform a driver of the rear object car of the emergency situation by the provision of a display.

Abstract: Optical distance measurement apparatus and method. The apparatus comprises a light emitting circuit, a light receiving circuit, a trigger signal generation circuit, a pollution sensor, a diode abnormal state sensor, a control/time-distance conversion circuit, a cleaning device and a car collision prevention device. The pollution sensor receives a part of a light beam which is emitted from the light emitting circuit and then reflected from protecting glass mounted on a front side of the apparatus, to sense a variation in a reflectivity of the protecting glass, and discriminates a polluted state of the protecting glass in accordance with the sensed result.