Ultrasonic Proximity sensor

Ultrasonic Proximity sensor:

The ultrasonic proximity sensor uses a transducer to send and receive high-frequency sound signals. If the incoming target sound range is reflected again to the sensor, causing the sensor to activate or not activate the output circuit.


Piezoelectric ceramic plates are installed inside the sensor surface. This can send and receive high-frequency pulses. The high-frequency voltage applied to the disk causes it to vibrate at the same frequency.

Plate vibrations produce high-frequency sound waves. If sent a pulse attack the object will reflect the sound, then the echo is generated. The duration of the reflected pulse is evaluated on the transducer. If the target enters the preset operating area, the sensor output changes state. If the target leaves the preset operating area, the output returns to the initial state.

Working of Ultrasonic Proximity sensor:


The time interval between the signal sent and the echo is directly proportional to the distance between the object and the sensor. The operating range can be set in the context of width and position within the sensor area.

The upper limit can be set on all sensors. The lower limit can be set only with certain versions. Objects that cross the upper border do not produce changes to the sensor output. This is known as “blanking out the background.

On some sensors, blocking range also exists. This is between the lower bound and the blurred area. An object in the blocking range will prevent identification of targets in the operating area. There is an output signal supplied to the operating area and output area.

The blurred area is in front of the sensor. This area depends on the sensor, which is from 6 to 80 cm. An object placed in a blurred area will produce an unstable output. The free area must be maintained around the sensor to give access to the side cone.

Benefits of using high frequency in Ultrasonic sensor:

  • Uninterrupted coverage
  • Electrically unstable reach
  • Can be concealed behind trim panels
  • Detects through glass, wood, walls etc.,
  • Operates irrespective of ambient temperature and temperature of an object.



Instrumentation Engineer

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