Method and device for contactless monitoring of a warp (weaver's) loom (beam)

A contactless monitoring device is used to determine the lap (bat) radius and contains a digital distance measuring device which operates in accordance with the principle of triangulation and contains in the base a radiation receiver (12), which can be influenced by the radiation reflected from the warp beam, a rotating radiation emitter (9) and a radiation receiver (14) which is directly irradiated by the radiation emitter. A first counter has a start connection to the first radiation receiver and a stop connection to the first radiation receiver. A first counter (15) is started and stopped by the signals of the two radiation receivers. A second counter is started and stopped cyclically with each rotation of the radiation emitter. The digital evaluation circuit contains a computing stage (17) for the purpose of cyclic formation of the ratios of the count values of the first and second counters. A storage device (22) stores pulse counts of distance values from a finely graded distance value pulse counter chain which are determined in a calibration operation. The pulse counts of distance values for the respectively measured distance from the warp beam are compared in a comparison stage with the stored pulse counts for distance values in order to determine the warp beam radius.