YARN FEEDER WITH ROTARY STORAGE DRUM AND YARN-UNWINDING SENSOR

摘要

A motorized rotary drum (12) supported on a motor housing (16) bears a plurality of yarn loops (Y) wound thereon, such loops being adapted to be unwound upon request from a downstream machine. A yarn-unwinding sensor comprises light-emitting means (42) and light-receiving means (45) both of which are integral with the motor housing (16). Light-guiding means which are integral with the drum (12) guide the light from the light-emitting means (42) to a window (30c) which is defined on the rotary drum (12) in a position such that it is repeatedly engaged by the yarn during its rotary unwinding motion, and vice versa. A reflecting surface (43) reflects the light coming out of the window (30c) back towards the window (30c). Light-deviating means (44) which are integral with the motor housing (16) deviate the light coming back from the window (30c) towards the light-receiving means (45). The unwinding of a yarn loop from the drum (12) is determined on the basis of the variation of light resulting from the yarn transiting on the window (30c).