Most ultrasonic sensors are based on the principle
of measuring the propagation time of sound in air. Packages of ultrasonic sound, so called
bursts, are emitted by the sensor, reflected by an object and received again by the sensor.
The transducers in the sensors, with sonic frequencies far outside the range of human hearing,
constantly change between transmission and reception during operation. The returned echo signals
are evaluated by the integrated electronics of the sensor. Depending on the sensor type, either
digital or analog information is then issued at the output.
Unlike optical sensors, influences
such as changing colors, transparency or high reflectivity have no bearing on the detection of
objects. Ultrasonic sensors maintain their excellence even in harsh environments. They are extremely
resistant to dirt, and process reliability is not impaired by dust, smoke, vapors, or other contaminants.
