Light sensor for detecting object in monitoring region on detection plane

摘要

The light sensor (1) has two transmitters (3,3') and two receivers (4.4') arranged so that the transmitters transmit light beams (12,12') at a common angle to the detection plane and the receivers receive light (13) reflected at an angle between 80 and 130 deg. to the transmitted light and intersecting the transmitted light in the detection plane. Polarising arrangements are placed after the transmitters so that light incident on the object (2) from one is polarised parallel to the incidence plane and light from the other perpendicular to the incidence plane. Polarising arrangements are placed before the receivers and the difference between the receiver signals evaluated w.r.t. a variable threshold by an evaluation unit (9) which controls the activation of one transmitter within a predefined time interval.