Ultrasonic distance detector

Abstract

Abstract PURPOSE:To distinguish securely a detour output from a reflection output by perform arithmetic on distance on the basis of the time difference when the variation rate of the envelope of an ultrasonic receive signal waveform exceeds a specific value, after ultrasonic wave transmission. CONSTITUTION:An oscillator 1 oscillates a transmit wave S1 of the resonance frequency of a transmitting microphone 2 and a receiving microphone 3 to transmit an ultrasonic wave R1 to a body 10 to be measured. The reflected ultrasonic wave R1' is received by the receiving microphone 3 and converted into an electric signal, which is inputted to an amplifier 4. The amplified reflected signal S2 is inputted to a detecting and smoothing circuit 5, whose output envelope E is passed through a differentiating circuit 14 to generate an output S3'. Then, S3' is compared by a comparator 6 with a reference voltage D' from a reference voltage generator 15. On the other hand, a mask signal S5 passed through a time delay circuit 8 is ANDed with a decision signal S4 by an AND circuit 9, which generates a signal S6. The counted value of a counter 11 which counts pulses of a clock 14 is outputted to a latch circuit 12 at the output timing of the AND circuit 9.

Inventors

• 👤 Kiyoshi Takeuchi
• 👤 潔 竹内
• 👤 Hiroshi Kobayashi
• 👤 博 小林
• 👤 Hiroaki Obayashi
• 👤 大林　博明

Bibliographic Details