Description

Ultrasonic sensing works much like single-ended capacitive sensing except instead of an electric field, it uses high-frequency sound energy. A transmitting transducer ("speaker") in the base of the sensor transmits sound to a receiving transducer ("microphone") in the top of the sensor. The label web reduces the amount of sound reaching the receiver. The thicker the web, the less sound at the receiver. The sensor electronics measure the sound pressure at the receiver and triggers the control when a label edge is detected. This technology has no sensitivity to metallic materials. This is the newest type of clear label sensor., but not necessarily the best.