JPS57184912A - Detector for condition of road surface - Google Patents

Abstract

PURPOSE:To exactly detect the condition of road surface deemed to make it impossible for car to ride over by using a detection system in which abnormal distance is detected and confirmed continuously before a vehicle moves by a given distance from the time when a distance detector provided forwardly by a given distance from the axle of the front wheel. CONSTITUTION:A supersonic pulse a is emitted at the time t1 from a supersonic wave oscillator 2, reflected wave from the road surface is received at the time ta by a supersonic wave receiver 3, and received wave b is converted into receiving pulse c in a receiving circuit 4 and put in a received signal decision circuit 5. In the circuit 5, the rising time t2 of the distance comparison signal d of a reference pulse generation circuit 1 is compared with the rising time ta of the signal c, and when t1<ta<t2, obstacle signal e becomes zero. Then, when the detection time of reflected wave by grooves, etc., is between the rising time and breaking time of the signal d, a counter circuit 8 is actuated by the signal e, abnormal distance signal is detected continuously by the circuit 5, an alarm device 9 operates when reaching a count value corresponding to the distance of about 40cm, and what is impossible for car to ride over is detected.