In light-band sensors, the light of the integrated illumination is reflected by an opposite foil and received by the diode array. The length of the diode array together with the optics determines the measuring field size. Thanks to the narrow diode array, the measuring field is only a narrow strip.
If an object shadows a part of the light, no light will fall on the corresponding part of the diode array. The integrated micro-controller analyzes the dark areas and the dark-bright transitions and calculates the corresponding analog value depending on the measuring mode. The light-band sensor has a parallel radiation field, which makes an object appear to be the same size at any measuring distance.