Ultrasonic SensorsBasic knowledge about ultrasonic sensors: What is an ultrasonic sensor?

Ultrasonic sensors use ultrasonic waves for things like detecting the distance to an object, detecting the presence or absence of objects, and detecting the movement of objects.
An electrical signal is applied to an ultrasonic wave transducer (transmitter) to transmit ultrasonic waves. These are then received by a receiver and converted into an electrical signal. For the various detection methods, refer to “What can you do with ultrasonic sensors?”

This term generally refers to sound waves at frequencies higher than the range from low frequencies to the top of the audible frequency range (0 Hz to 20 kHz). ultrasonic waves are inaudible to humans.

v:Speed of sound (346 meters per second at 25°C）
f:Frequency
λ:Wavelength

Here we describe the principle of sound production whereby electrical signals are converted into ultrasonic waves and ultrasonic waves changed into electrical signals as described below.

A piezoceramic has the following characteristics, according to the voltage direction:
← The ceramic expands. →
→ The ceramic contracts. ←
This process is repeated, causing vibrations in the air that generate ultrasonic waves.