Ultrasonic SensorsBasic knowledge about ultrasonic sensors

A sensor technology enabling “detection” that is the first step toward the IoT society.
Ultrasonic sensors employing ultrasonic waves are expected to come into widespread use in a variety of fields such as mobility. Learn basic knowledge about things like how ultrasonic waves work and how they can be used.

Generally speaking, the term “ultrasonic waves” 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 sensors receive and transmit ultrasonic waves by converting vibrations into electrical signals via the expansion and contraction of a piezoceramic material and by converting electrical signals into vibrations.

Among the properties of ultrasonic waves are that their propagation speed differs depending on the medium through which they travel and that their directionality and resolution vary according to frequency. Such performance characteristics can affect the measurement distance and accuracy as well as the detection range.

Since the propagation speed of ultrasonic waves differs depending on the medium, ultrasonic waves are either transmitted through or reflected by different media. This property of reflection is used mainly to detect the presence or state of objects, and for distance detection.

Here we describe some precautions regarding aspects such as the housing and mounting to ensure efficient reception and transmission by ultrasonic sensors.

Circuits for distance detection use a method called pulse reflection, measuring the reflection time between the transmitted ultrasonic wave pulse and the received pulse. The reflection time to the object can then be used to calculate the distance to that object.

Learn about the features of the drip-proof type, high-frequency type and open structure type (lead type).