Pepperl+Fuchs Blog

Diffuse Use – Ultrasonic Diffuse Mode Sensors Are Everywhere

Posted by Patricia Stafford on Thu, Jun 04, 2015

What are ultrasonic diffuse mode sensors?

Diffuse mode is the most common way to operate an ultrasonic sensor. In this mode, the transducer is contained in the same housing as the evaluation electronics and acts as both an emitter and receiver. Because of this design, this type of ultrasonic sensor works by continuously switching between transmission and reception modes and waiting for echo signals.


What is the principle behind ultrasonic diffuse mode sensors?  How do they work?

Ultrasonic diffuse mode sensors work by emitting a three-dimensional sound cone which creates a beam angle that defines the sensing range. When a target object enters this range, the object is detected. To calculate the distance to the object, the sensor measures the amount of time between the emission of the sound pulse and its return echo.

How do I mount a diffuse mode sensor?

Most diffuse mode sensors, being cylindrical, are easily mounted on a bracket or by using a through hole. This method of mounting works perfectly fine for the vast majority of applications where the target to be sensed is far away, and it doesn’t matter if the sensor sticks out several inches from its mounted base. In the case of the F65 series sensor shown here from Pepperl+Fuchs, it mounts with a special gasket to the top of a tank and features an attractively low profile of 30 mm.


When should I use a diffuse mode sensor instead of a photoelectric sensor?

Like thru-beam ultrasonic sensors, diffuse mode sensors can detect objects of any color or transparency with identical accuracy. They can also handle the dusty and dirty environments where photoelectric sensors don’t work.

Why should I use diffuse mode instead of thru-beam ultrasonic sensors?

Diffuse mode sensors are simple and cost effective for many common applications.

What can you do with ultrasonic diffuse mode sensors? What kinds of applications are they used in?


Level measuring for industrial goods
Ultrasonic diffuse mode sensors can detect a wide variety of substances including liquid chemicals, fertilizers, waste water, sludge, mud, sand, gravel, crushed rock, and more.

Mobile equipment
Ultrasonic diffuse mode sensors allow garbage trucks to automatically detect trash containers. These sensors are also an ideal fit for forklifts where they can gauge the distance of the vehicle to a pallet, as well as fork insertion depth.

Object/people presence
Ultrasonic diffuse mode sensors can detect objects as large as cars and as small as printed circuit boards.  These sensors can detect people as well.

Scrap and recycling
Ultrasonic diffuse mode sensors are unaffected by dust plumes and immune to ambient acoustic noise.  With sensing distances to 30+ feet, these sensors can detect target objects regardless of their color, size, or shape. Uses for these sensors include detecting the presence of scrap bales, monitoring conveyor belts and scrap bin level, and the positioning of overhead cranes.

Collision avoidance
Ultrasonic diffuse mode sensors are used on overhead conveyors and underneath platform perimeters to provide safety for people and processes.

Food and beverage tank level control
Ultrasonic diffuse mode sensors can detect how much of a food or beverage there is in a tank, for example, milk, cheese, grain, etc. In this case, the sensors consist of a hygienic 100% stainless steel design.

Print and paper
Ultrasonic diffuse mode sensors are ideal for roll and web monitoring, roll diameter monitoring, or simple presence / absence detection.

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Topics: Ultrasonic Sensors

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