Apparatus for detecting break or slackening of yarn

An apparatus for detecting a break or unusual slackening of a yarn in a plurality of yarns, comprising:

• a detector assembly consisting of a plurality of detecting units juxtaposed end-to-end in a longitudinal direction, each of the detecting units comprising a magazine block having front and rear ends substantially parallel with said longitudinal direction and formed with an aperture open at both side ends of the magazine block, the apertures in the magazine blocks of the individual detector units having respective center axes substantially in line with one another, said apertures forming an elongated continuous bore throughout said magazine blocks substantially in parallel with said longitudinal direction:
• a light-intercepting element which is rotatable about an axis of rotation through said magazine block and substantially parallel with said longitudinal direction and which projects outwardly from the front end of the magazine block, the light-intercepting element being rotatable about said axis of rotation between a first angular position uncovering the aperture at one axial end of the aperture, a second angular position in part covering the aperture at said axial end and a third angular position opposite to said second angular position across said first angular position and uncovering said aperture, said light-intercepting element being in said first angular position by a properly tensioned yarn engaging the element and in said third angular position when the detecting unit including the intercepting element is to be out of use;
• biasing means urging said light-intercepting element to turn toward said second angular position about said axis of rotation;
• stop means for bearing said light-intercepting element thereon when the light-intercepting element is in said second angular position;
• and manually-operated retaining means supported on said magazine block for releasably holding said light-intercepting element in said third angular position thereof;
• light-emitting means which is positioned externally of and in proximity to the aperture in the magazine block disposed at one longitudinal end of said detector assembly and which is operative to project a beam of light into said bore;
• and
• light-sensitive signal generating means positioned externally of and in proximity to the aperture in the magazine block at the other longitudinal end of said detector assembly and operative to deliver a signal in response to the beam of light emitted from said light-emitting means and reaching said signal generating means through said bore.