Edinburgh Napier University

  A sensor system for detecting a movement of an Infrared light source (29) in a predetermined direction of movement (30) has at least one pair of infrared light sensors consisting of two infrared light sensors (4, 5; 36, 37) which are arranged beside one another with respect to the direction of movement (30) and thereby define a sensor coverage section (17), which is determined by the distance between the ends (16) of the infrared light sensors (4, 5; 36, 37) which face away from one another with respect to the direction of movement (30), and are set up in such a manner that, during irradiation with the infrared light source (29), said sensors provide electrical signals, the charge signs of which are opposing, for detecting the movement of the infrared light source (29) in a manner such that said signals can be tapped off, wherein the sensor system (1) has a window (7) between the infrared light sensors (4, 5; 36, 37) and the infrared light source (29), through which window the infrared light from the infrared light source (29) can be beamed onto the infrared light sensors (4, 5; 36, 37) and behind which window the infrared light sensors (4, 5; 36, 37) are arranged and the arrangement and extent of which are matched to the width (41) of the window (7) in the direction of movement (30) in such a manner that, beyond a predetermined limit distance (20) away from the window (7), the infrared light sensors (4, 5; 36, 37) each have a full shine area (22, 23) which defines the locations from which the infrared light source (29) fully shines on only one of the infrared light sensors (4, 36 or 5, 37), wherein the full shine areas (22, 23) do not spatially overlap beyond the limit distance (20), and the window width (41) is shorter than the sensor coverage section (17) in the direction of movement (30).