Patent ID: 8596328

Claim:
An arrangement for covering an architectural opening, comprising: a covering material; a cord having a first end and a second end, wherein said first end is operatively connected to the covering material for extending and retracting the covering material and the second end is accessible to be pulled by a user; and a bail lock mechanism including: an outer bail and an inner bail, wherein said inner bail and outer bail define a cord passage gap between the inner bail and the outer bail and at least one of said inner and outer bails defines a cord guide surface having a left end and a right end and varying in cross-sectional profile from left to right; wherein the cord passes through the cord passage gap between the inner bail and the outer bail, and wherein there are at least two paths along which the cord can track as it travels through the cord passage gap, including a first path, along a portion of the cord guide surface having a first front-to-back cross-sectional shape, where there is a first amount of bend in the cord and a first amount of friction applied to the cord by the bails, and a second path, along a portion of the cord guide surface having a second front-to-back cross-sectional shape, where there is a greater bend in the cord and greater friction applied to the cord by the bails; and further comprising a capstan, wherein a portion of the cord between the first end of the cord and the bail lock mechanism is wrapped around the capstan; wherein pulling the second end of said cord raises the covering material, and wherein, when the cord is tracking along the first path and the user releases the cord, the friction applied to the cord by the bail lock is low enough that the cord surges the capstan and the covering material lowers in a controlled, gradual manner.