Ultrasonic sensors from Murata emit ultrasonic waves in the air that reflect off of objects. The reflected sound is then received by the sensor. This technology is used for detection of objects in burglar alarms and automatic doors as well as for range measurement in automotive parking assistance systems.
Ultrasonic sensors feature a composite oscillating body combining the oscillator — which joins a metal plate and piezoelectric ceramics — with a resonator. This body is elastically fixed to the base and housed in a case. The resonator is shaped like a funnel to efficiently radiate the ultrasonic waves generated by the oscillating body into the air and to effectively concentrate ultrasonic waves from the air on the center of the oscillator.
“Sound pressure” is the most important parameter of open-structure ultrasonic sensors. In distance measurement applications, the higher the sound pressure of the ultrasonic sensor, the longer the sensor’s range.
SMD (Surface Mount Device)-type ultrasonic sensor measure intermediate range, since it control sound pressure loss because of miniaturisation. Miniaturised SMD-type ultrasonic sensor has succeeded in minimal mounting space, and it enable improved flexibility for designing.