Detector for edge of belt between retro-reflector and sensor

摘要

The sensor (3) has a rotary mirror (18) which deflects a beam (15) from a radiation source (5) across the direction of the belt's (1) travel, and scans an observation field. A retro-reflex beam (24) reflected on the retro-reflector is detected by a receiver (28). A second beam (21) hits the rotary mirror at a second impact point (R2) spaced apart from the first impact point (R1) of the first beam. The second retro-reflex beam (29) reflected from the impact point of the second beam on the retro-reflector (4) is detected by a second (33) or by the same receiver. The signals of the second retro-reflex beam in the evaluation circuit for determining a second position date of the edge of the belt, together with the first position date, serve to determine the spatial position.