Photoelectric sensor with background suppression

with foreground suppressiondiffuse reflectiverectangular

This form of sensing is commonly referred to as the proximity mode. Light from the emitter strikes the target which causes it to become diffused at arbitrary angles. Some light returns directly to the receiver and the target is detected. Factors pertaining to the sensing range are color, size and finish of the target. The actual sensing range for each model is based upon a “white test card.” The white card has a 90% reflectivity factor and is considered a “standard target.” Darker colored or matte finished targets provide less reflectivity; therefore the sensitivity must be increased or the entire sensor must be positioned closer to the target. When this situation occurs, care should be taken so that a brighter target in the background is not mistaken as the actual target.