Looped-cord system for window coverings

摘要

A looped-cord system includes a beaded cord having a set of beads connected in series to form a loop with a space between each pair of adjacent beads. In one embodiment a stop sized to fit within the space between a pair of adjacent beads is attached to a housing. A resilient finger located opposite the stop pushes a portion of the beaded cord adjacent to and not engaging the sprocket against the stop so the stop is within a space between a pair of adjacent beads, thereby preventing movement of the cord loop. Applying tension to the cord loop overcomes the resilient finger and moves the cord away from the stop enabling movement of the cord loop. In another embodiment a key engages the sprocket preventing the sprocket from turning until tension is applied to the cord loop by proper installation of the tensioner on the cord loop.

主权项

1. A drive unit for a looped cord system comprising:
a housing; a sprocket attached to the housing; a beaded cord loop comprised of beads connected in series to form a loop with a space between each pair of adjacent beads, the beaded cord loop hung on the sprocket such that there will be two portions of the beaded cord loop adjacent to and not engaging the sprocket which two portions will be parallel to one another when no force acts on those portions of the beaded cord loop; a stop attached to the housing; a resilient finger opposite the stop, the resilient finger pushing one of the two portions of the beaded cord loop adjacent to and not engaging the sprocket against the stop, thereby preventing movement of the beaded cord loop, and the two portions of the beaded cord loop are not parallel to one another; wherein applying tension to the beaded cord loop will overcome the pushing of the resilient finger and move the beaded cord loop away from the stop enabling movement of the beaded cord loop; and a tensioner that is configured to be mounted to a non-movable structure such that the tensioner is spaced apart from the housing when the tensioner is mounted, the tensioner sized and configured such that a segment of the beaded cord loop passes along a portion of the tensioner such that the beaded cord loop extends from the housing to the tensioner and has two parallel spaced apart segments linearly extending from the housing to the tensioner when the tensioner is mounted to the structure; a shroud that is positioned between the housing and the tensioner to surround a portion of each of the two parallel spaced apart segments of the beaded cord loop that extends from the housing to the tensioner when the tensioner is mounted to the structure; the tensioner, sprocket, stop, finger and housing arranged such that the beaded cord loop is tensioned when the tensioner is mounted to the structure such that the beaded cord loop is under tension that overcomes the pushing of the resilient finger to prevent the resilient finger from pushing the beaded cord loop against the stop to enable movement of the beaded cord loop.