Abstract: In a photoelectric yarn-break/yarn-stop detecting device in which a light emitter element and a photoelectric transducer element are positioned in such a manner that the yarn to travel through the detecting device passes through the beam of light emitted from the light emitter element to the photoelectric transducer element for detecting a break or a stop of the yarn in the absence of noises in the signal current produced by the photoelectric transducer element, the light emitter and photoelectric transducer elements and the path of the light from the light emitter element to the photoelectric transducer element are enclosed within a structure adapted to prevent passage of light and an ingress of dust and flue from the outside of the detecting device.

Abstract: An apparatus for detecting break or unusual slackening of a yarn in a plurality of yarns, comprising a plurality of a units each having a magazine block formed with an aperture to form part of a continuous bore in the assembly of the magazine blocks, a light-intercepting element having a first angular position uncovering the aperture and a second angular position covering the aperture and a yarn-pass element connected to the light-intercepting element, the yarn-pass element of each of the detecting units being retained by each of the yarns in a raised position holding the associated light-intercepting element in the first angular position thereof; light-emitting means positioned at one end of the bore in the assembly of the detecting units; and light-sensitive signal generating means positioned at the other end of the bore, the beam of light from the light-emitting means being passed throughout the bore and reaching the signal generating means when the light-intercepting elements of all of the detecting units