Through-beam sensors are a true time proven solution to many photoelectric applications. These sensors can detect anything regardless of color, texture or reflectivity, all that needs to happen is the light beam needs to be blocked. Add an optional aperture and you can detect even the smallest of parts. With the various light sources available and you can detect small parts (with a laser light) or blast through the harshest of environments with an infrared light source. These sensors come in several housings or styles for instance tubular (as small as 8mm), block, fiber optic and the fork style sensor.
Through-beam sensors are used in applications that require sensing ranges from 2 millimeters to 100 meters and in some cases longer. Since these sensors require a light emitter and a receiver that are in separate housings, you have to mount and wire each component separately. Once mounted you have the task of aligning the receiver to the emitter, which could be a tedious task. Just imagine trying to line up the devices that use an infrared light source with a working range of 50 meters or even 150 millimeters.
Fork sensors, also referred to, as c slot or u slot, are the ideal through-beam sensor. First, they are self-contained in one housing so there is no need to align the emitter and receiver. This is important because in the harsh environments if the sensor is bumped or jarred the receiver and emitter stays aligned. Secondly, the housings are typically metal offering an extremely robust sensor. Third, since the sensor is integrated into one housing installation is much easier, one part to mount and only one wiring connection. These sensors are available from 5mm to 220 mm wide openings.
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When an application calls for an Ultrasonic sensor it is very important to understand the principles of operation. The most important question in sensor selection… what is the operating distance needed? How far away can I be from the target? Understating “The Blind Zone” will be the key to selecting the proper sensor for your application.
“The Blind Zone” is the shortest permissible sensing range. This means that no objects or targets are permitted within the minimum working area (“Blind Zone”) as this would false trigger the sensor. For example we have an application where we need to see our target at 80mm away. We could select a sensor that has an operating distance of 20….150mm. This means we can see our target down to a minimum distance of 20mm and a maximum range of 150mm. anything below the 20mm is the “Blind Zone” and out of our working range of 20…150mm.
The shortest permissible sensing range
This is determined by the blind zone of a sensor. No objects or are permitted within the blind zone, since this would cause faulty measurements or readings.
So as you can see it is very important to understand your minimum working area and where the “Blind Zone” begins within the working range of the senor. If you have any questions on this topic or other questions on Ultrasonic sensor selection, please leave a comment below.
In many cases, the mechanical components of an older machine can basically operate forever. Critical surfaces can be remachined, and bearings and gears can be replaced again and again to restore lost accuracy and repeatability.
But what about the control system? Sometimes older machines are retrofitted with a new controller to enhance its productivity and extend its useful life. Such refits should not stop with the controller alone. Many of the greatest improvements in machine performance can be obtained by upgrading the entire sensor package as well. Sensors are at the heart of today’s automation systems. They provide the critical information and feedback about what the system is doing, and the status and condition of products being handled and produced.
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