ULTRASONIC TYPE DISTANCE MEASURING DEVICE AND ULTRASONIC TYPE DISTANCE MEASURING METHOD

摘要

PURPOSE:To eliminate errors in a measured distance even if a sensor gain is changed due to changes in environment by using a differentiating means and a signal processing means for an ultrasonic receive signal from an object to be measured. CONSTITUTION:A received ultrasonic signal from an object to be measured is amplified and detected to be converted into an enveloping signal and outputted to a differentiating means 16. In order to find out the time of change of a wave detection signal voltage, the differentiating means 16 converts the enveloping signal into a differential signal, outputs pulses of only its rising parts from a signal processing means 17 to a time difference measuring means 18, measures the rise time interval between a control pulse and a received pulse, and measures the distance up to the object to be measured. By using the differentiating means 16 and the signal processing means 17, the time difference measuring means 18 measures the time difference at the same timing constantly even if the sensor gain is changed due to change in environment. Errors in the measured distance due to change in electrical characteristics of a sensor can thus be reduced.