Ultrasonic-wave distance measuring method and apparatus of separate transmission and reception type reflection system

An ultrasonic-wave distance measurement method of a separate transmission and reception type reflection system which receives an ultrasonic wave emitted from an ultrasonic-wave transmission sensor and reflected at a distance measured object by an ultrasonic-wave reception sensor, measures a time from the transmission of the ultrasonic wave to the reception of the same, and performs sensitivity correction in accordance with a distance to a specific distance measured object when measuring the distance between the ultrasonic-wave transmission and the distance measured object from the obtained time,

• said method including the following steps of:
• measuring an elapsed time from transmission when an ultrasonic wave is emitted from the ultrasonic-wave transmission sensor to the distance measured object to reception of the same, calculating a provisional distance from the obtained time, measuring attenuation characteristics of the reflected ultrasonic wave by comparing an amplitude with a reference reflection ultrasonic wave, and preparing ultrasonic-wave sensor sensitivity correction data from the attenuation characteristics with respect to a specific type of the distance measured object and the ultrasonic-wave transmission sensor or the ultrasonic-wave reception sensor;
• starting counting a time simultaneously with the emission of an ultrasonic-wave signal to the distance measured object by driving the ultrasonic-wave transmission sensor;
• stopping the counting simultaneously with the reception of the reflected wave by the ultrasonic-wave reception sensor, measuring an elapsed time from the driving of the ultrasonic-wave transmission sensor to the reception of the reflected wave by the ultrasonic-wave reception sensor, calculating a provisional distance between the ultrasonic-wave transmission sensor or the ultrasonic-wave reception sensor and the distance measured object based on the elapsed time, generating the ultrasonic-wave sensor sensitivity correction data for reception corresponding to the calculated provisional distance, and enabling the sensitivity correction based on said sensor sensitivity correction data in an ultrasonic-wave signal sensitivity correction portion for reception;
• starting counting a time simultaneously with the emission of the ultrasonic-wave signal to the distance measured object by driving the ultrasonic-wave transmission sensor again;
• and
• stopping the counting simultaneously with the reception of the reflected wave by the ultrasonic-wave reception sensor again, measuring a time from the driving of the ultrasonic-wave transmission sensor to the reception of the reflected wave by the ultrasonic-wave reception sensor, and calculating an actual distance between the ultrasonic-wave transmission sensor or the ultra-sonic wave reception sensor and the distance measured object based on the obtained time.

An ultrasonic-wave distance measuring apparatus of a separate transmission and reception type reflection system which receives an ultrasonic wave emitted from an ultrasonic-wave transmission sensor and reflected at a distance measured object by an ultrasonic-wave reception sensor, measures a time from the transmission sensor of the ultrasonic wave to the reception of the same, and measures a distance between the ultrasonic-wave transmission sensor or the ultrasonic-wave reception sensor and the distance measured object from the obtained time,

• said apparatus comprising:
• a transmitter for performing drive control of the ultrasonic-wave transmission sensor;
• a receiver for performing distance measurement by processing a signal from the ultrasonic-wave reception sensor;
• and
• a control means for controlling the transmitter and the receiver;
• said receiver comprising:
• a type setting device for setting a type of the distance measured object;
• a sensitivity correction circuit for correcting a sensitivity of the received signal in the ultrasonic-wave reception sensor;
• a detection circuit for detecting an output of the sensitivity correction circuit;
• and
• a distance measurement calculation control means;
• said distance measurement calculation control means storing in advance sensitivity correction data of the ultrasonic-wave reception sensor obtained by measuring a received wave by the ultrasonic-wave reception sensor when an ultrasonic-wave is emitted to the distance measured object by the ultrasonic-wave transmission sensor and generating the sensitivity correction data of the ultrasonic-wave reception sensor from the measured data with respect to each type of the distance measured object and various distances between the distance measured object and the ultrasonic-wave transmission or the ultrasonic-wave reception sensor;
• the control means making the transmitter perform a first ultrasonic-wave transmission operation from the ultrasonic-wave transmission sensor and the receiver to start counting a time simultaneously;
• the distance measurement calculation control means of the receiver;
• measuring a time from the first driving of the ultrasonic-wave transmission sensor by the transmitter to the reception of the reflected ultrasonic-wave by the ultrasonic-wave reception sensor;
• measuring a provisional distance between the ultrasonic-wave transmission sensor or the ultrasonic-wave reception sensor and the distance measured object;
• and
• generating ultrasonic-wave sensor sensitivity correction data corresponding to the calculated provisional distance and a type of the distance measured object set by the type setting device, setting the sensor sensitivity correction data to the ultrasonic signal sensitivity correction circuit for reception, and implementing the completion of setting the ultrasonic-wave sensor sensitivity correction data to the control apparatus;
• the control means, in response to the completion of the processing of the distance measurement calculation control circuit, making the transmitter perform a second ultrasonic-wave transmission operation and the receiver start counting simultaneously;
• and
• the distance measurement calculation control means of the receiver;
• measuring an elapsed time from the second driving of the ultrasonic-wave transmission sensor in the transmitter to the detection of reception of the reflected ultrasonic-wave and calculating the actual distance between the ultrasonic-wave transmission sensor or the ultrasonic-wave reception sensor and the distance measured object by using the elapsed time.