Optical thread presence set improves rejection of interfering effects

摘要

An appts. for recognition of a tear in the thread in a textile machine has a light source, which emits a narrow light beam, and a detector. The main beam is located in the path of a broken expelled thread where a signalling device in the detector responds to its passage through the beam. Here the beam is from a laser and on the opposite side of the deviating thread section (6) from the light source (2) there is a light absorber (5) across the path of the main laser beam (3). The detector is located beside the light source so that, when the thread is passing through the main beam, a scattered reflection beam (7) is incident on the detector (9) where the signalling device is designed to respond to the reflected beam.