Diffuse photoelectric sensors have been and are used to successfully solve numerous applications in automation. However, there are some applications that are too difficult or impossible to solve with standard diffuse sensors. In some cases, these difficult applications can be solved with a background suppression sensor that is also based on the diffuse operation principal. So the question is then raised, what makes the background suppression sensor capable of solving these difficult applications?
This may be a good time to review… Diffuse sensors operate on the principal that when a light source is shined on a surface, the light is scattered or diffused in many directions. A small portion of the light is reflected back to the sensor receiver. The receiver used in this style of sensor is designed to be sensitive to a smaller or larger amount of light, depending on the sensor configuration, that is reflected back from the target surface. There are a number of factors that affect how well diffuse sensors operate including, but not limited to, surface finish, color, texture or surface irregularities, target size, dirty or dusty environment and the background of the application.
Background sensors, sometimes referred to as BGS, actually have two receivers built into the sensor. These two receivers detect the angle of the light reflected back from the target, referred to as triangulation. If the target is between the focal point and the receiver the light is reflected to one receiver and if the target is beyond the focal point the light is reflected to the second receiver. The sensor compares the amount of light on each receiver and sets the output accordingly.