Verfahren zum Abtasten eines Fadens und Fadenabzugssensor

摘要

In a process for scanning yarn having a predetermined length and intermittently unwound from a yarn reserve wound (3) around the feeding drum (2) of a yarn-feeding device (F) for mechanical looms (L), a sensor (S) is used whose yarn (Y) pulse acceptance for at least one first yarn pulse changes when yarn speed increases and/or when at least one first winding signal is generated. A second yarn pulse acceptance for subsequent faster yarn pulses is thus obtained, as well as a non-acceptance of interference pulses that are slower than the second yarn pulses. A yarn unwinding sensor (S) suitable for carrying out this process is characterised in that it is provided with filtering means with two different selective filtering modes that differ by their acceptance of yarn pulses generated at different yarn unwinding speeds. The filtering means may be adjusted from a first filtering mode into at least another filtering mode when the yarn unwinding speed increases.