| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent erroneous detection of object while preventing increase of manufacturing cost.SOLUTION: When completing a detection process from a first to fourth sets, a memory sets 1 to a storage rejoin Ponly in which all of four sets have detection signal of 1; and rewrites with 0 a storage rejoin Pin which any one of the sets has a detection signal of 0. At a point when the detection process on the fourth set is terminated, an arithmetic section 3 selects storage rejoin Pwhich has the detection signal of 1, and calculates a reciprocation time of an ultrasonic pulse on the basis of a lower limit value of sampling period×(k+1)+elapsed time to obtain a distance up to the object based on the reciprocation time. That is, when the detection signals of every sets from the first to the fourth are stored in the memory, four memories having n+1 storage rejoins Pare required. Contrarily, the object detector of the invention requires only one memory which has n+1 storage rejoins P. Thus, erroneous detection of object can be reduced while preventing increase of the manufacturing cost.</p> |
