Patent ID: 7163044

Claim:
A roller shade assembly comprising: a rotatably supported roller tube that supports a flexible shade fabric for winding of the shade fabric thereon; and an elongated drape bar curved along at least a fabric-receiving portion of its length, the drape bar extending adjacent the roller tube for sliding receipt of the flexible shade fabric on an upper surface defined by the fabric-receiving portion of the drape bar, the fabric-receiving portion of the drape bar having opposite ends and defining an arc depth, A, between its opposite ends and an intermediate location therebetween, the drape bar supported such that the surface of the fabric-receiving portion is oriented at an angle, θ, from the horizontal, the drape bar located with respect to the roller tube such that each of the ends of the fabric-receiving portion of the drape bar is located at a distance, D, from the roller tube, the values of A, D, and θ related to each other according to the equation: ( A+D ) 2 +( A tan θ) 2 =[A tan θ+ D] 2.