Method of operating a light grating or grid for detecting and measuring objects

摘要

The method involves emitting linearly spaced parallel light beams (2) from a linear transmitter (4). The light is received by a receiver (6). A protective field (10) is defined between transmitter and receiver. The field is at an angle to the direction of movement of an object (12) entering the field so the beams are consecutively interrupted by the object so the speed of the object can be determined. The extension in the movement direction of a projection on the object is determined and compared with reference values. A switch signal is generated in dependence on the comparison.. Independent claims also cover a light grating.