MY111447A - Ultrasonic sensor - Google Patents

Abstract

AN ULTRASONIC SENSOR INTERMITTENTLY RADIATES ULTRASONIC WAVES TO AN OBJECT BY PREDETERMINED TIME INTERVALS SO AS TO DETECT REFLECTED WAVES. ON THE BASIS OF A DETECTION TIME BETWEEN A FIRST MOMENT, AT WHICH ULTRASONIC WAVE IS RADIATED TO THE OBJECT AND A SECOND MOMENT AT WHICH THE CORRESPONDING REFLECTED WAVE IS DETECTED, THE ULTRASONIC SENSOR COMPUTES A DISTANCE AGAINST THE OBJECT. IN ORDER TO ACCURATELY COMPUTE THE DISTANCE, A FIRST-ORDER REFLECTED WAVE, DIRECTLY CORRESPONDING TOTHE ULTRASONIC WAVE CURRENTLY RADIATED, SHOULD BE DISCRIMINATED FROM MULTIPLE REFLECTED WAVES CORRESPONDING TO THE ULTRASONIC WAVES PREVIOUSLY RADIATED. IN ORDER TO DO SO, PEAK VALUES CORRESPONDING TO THE REFLECTED WAVES ARE SEQUENTIALLY DETECTED; AND THEN, A MAXIMUM VALUE IS SELECTED FROM AMONG THOSE PEAKVALUES WHICH ARE DETECTED IN A CERTAIN PERIOD OF THE TIME. THIS MAXIMUM VALUE IS JUDGES AS A PEAK VALUE REPRESENTING THE FIRST- ORDER REFLECTED WAVE. THUS, THE DISTANCE IS COMPUTED ON THE BASIS OF THE DETECTION TIME RELATING TO THE MAXIMUM VALUE.FIG. 1