Car alarm system

PROBLEM TO BE SOLVED: To provide an alarm device which gives an alarm at an appropriate time in accordance with the change tendency of the distance between a vehicle and a preceding vehicle, makes the meaning of the alarm clear, and can improve driving sense by predicting the operation of automatic braking when the time till an operated automatic braking starting period becomes below a prescribed value. SOLUTION: The inclinations α and β of tangents C and D at present time T1 on a characteristic line A showing the change of the distance between the vehicles and a characteristic line B showing the necessary degree of automatic braking are operated. The intersection 6 of the tangents C and D is calculated based on the respective inclinations α and β, and time T2 in the intersection 6 is predicted as the operation start time of automatic braking. At time T4 when necessary time from present time T1 to predicted time T2 becomes the previously set threshold, t1, for example, collision alarm for predicting the operation of automatic braking is given in a form where light automatic braking is operated, for example. Thus, the operation of automatic braking can be predicted even if the relative speed is high. COPYRIGHT: (C)1998,JPO