Piezoelectric ultrasonic apparatus and method for determining the distance from a predetermined point to a target

Claim 1

A continuous distance determining detector for determining the distance from said detector to a target, including in combination: a piezoelectric ultrasonic transceiver, having a pulse transmitter for sending a sonic pulse signal to said target, a pulse receiver for receiving a reflection of said pulse signal from said target, means for generating a voltage signal corresponding to the time between said transmission of said pulse signal and receipt of said reflected signal, an analog output and a trigger output means for producing a voltage signal at the time of transmission of said sonic pulse, comparator means for comparing the voltage value of said analog output signal with a threshold level which must be exceeded by said analog output voltage before effect is given thereto, disable means connected to said trigger output for disabling detection during transmission of the transmitter pulse, enable means connected to the disable means for producing a time interval during which said analog output signal is valid, an AND gate connected to said comparator means and to said enable means, clock means for generating clock pulses, counter means connected to said clock means for counting said clock pulses, flip-flop means connected to said counter means and to the output of said AND gate and providing an output voltage, temperature sensing means for sensing the ambient temperature, temperature compensation and scaling means connected to said temperature sensing means for converting said ambient temperature into a correction voltage scaled to relate the ambient temperature to the output voltage of said flip-flop means, and multiplying digital-to-analog converter means connected to said flip-flop means and to said temperature compensation and scaling means for correcting the output voltage value of said flip-flop means in accordance with the effect of said ambient temperature, and for determining a corrected value for the distance from said detector to said target.

Claim 5

A method for instantaneously determining distance of an object from a given point, comprising: transmitting from said given point a piezoelectric ultrasonic pulse to said object, receiving the reflected pulse back therefrom at said given point, producing an analog output voltage therefrom, comparing said analog output voltage with a threshold level which must be exceeded by said analog output voltage before effect is given thereto, disabling detection during transmission of the transmitter pulse, enabling detection for a time interval during which said analog output is valid, applying the disable-enable outputs and the comparing output to an AND gate, generating clock pulses, counting said clock pulses, actuating the counting upon transmission of said pulse and de-actuating it upon receiving said pulse, to give the count during the interval between transmission and receiving, determining the distance from the counts by comparing the time taken with the known speed at which the pulse travels, and employing a multiplying analog-to-digital converter to temperature compensate the distance obtained from said determining step for validating the output thereof over a wide range of ambient temperatures and giving an accurate value of said distance of said object from said given point.

Claim 6

A method for instantaneously determining distance of an object from a given point, comprising: transmitting from said given point a piezoelectric ultrasonic pulse to said object, receiving the reflected pulse back therefrom at said given point, producing an analog output voltage therefrom, comparing said analog output voltage with a threshold level which must be exceeded by said analog output voltage before effect is given thereto, disabling detection during transmission of the transmitter pulse, enabling detection for a time interval during which said analog output is valid, applying the disable-enable outputs and the comparing output to an AND gate, generating clock pulses, counting said clock pulses, actuating the counting upon transmission of said pulse and de-actuating it upon receiving said pulse, to give the count during the interval between transmission and receiving, determining the distance from the counts by comparing the time taken with the known speed at which the pulse travels, and employing a multiplying analog-to-digital converter to temperature compensate the distance obtained from said determining step for validating the output thereof over a wide range of ambient temperatures and giving an accurate value of said distance of said object from said given point.