Frequently asked questions

What is resonance time?

Transmission-reception combined type ultrasonic sensors allow a single sensor to be used for both transmission and reception.
Even after the input signal stops, the sensor cannot receive waveforms until the sensor stops vibrating.
This duration during which the sensor continues to vibrate is called the resonance time. If the sensor has a long resonance time, it will not be able to detect short distances.
•The resonance characteristics are also affected by the method used to secure the sensor in place. (Refer to Basic knowledge: Usage.)

Directionality control

Directionality can be controlled by attaching a horn to the sensor.

  • The wider the horn, the narrower the directionality.
  • The longer the horn, the higher the frontal sound pressure.

Opening and length


Graph of opening and length


Opening and length table

What is the proper distance for a specific reflection target?


Detection target and detection distance

Ultrasonic sensors work with targets of any material or color. They are able to detect objects made of transparent glass or acrylic. Nevertheless, the reflection rate will differ according to the characteristics of the reflection target.


Distance range

•Reflected waves cannot be measured while the receiver is receiving direct waves.
→Short distance limit
•If an object is too far away, its reflected waves may be too weak to be measured.
→Long distance limit

Other questions