A photoelectric sensor basically comprises a light beam transmitter (light-emitting diode) and a light-sensitive receiver (photo-transistor). A light-emitting diode is an electronic semi-conductor component that emits light when an electric current flows through it. This light can be visible or invisible, depending on the transmission wavelength.

Detection occurs when an object enters the transmitted light beam and, in so doing, affects the intensity of the light at the receiver. As the light intensity at the receiver decreases, a point is reached whereby the output of the sensor changes state.

Depending on the model and application requirements, the transmission beam is either non-visible infrared (which is most common) or ultraviolet (for detection of luminescent materials). It may also be a visible red or green (for color mark reading etc.) and laser red (for long sensing distance and short focal length).

The advantage of LEDs is their very fast response. To render the system insensitive to ambient light, the current flowing through the LED is modulated to produce a pulsed light transmission. Only the pulsed signal will be used by the photo-transistor and processed to control the load.

Listed below are different variations of the XU range, each accompanied by a description to help you choose the perfect photoelectric solution. Read more …