Cordless, balanced venetian blind or shade with consistent variable force spring motor

A window covering of the type including a top member for supporting the window covering in a horizontal position and a bottom member, the window covering further including a cord means coupled to the bottom member and extending to the top member for supporting the bottom member as it is moved toward and away from the top member, wherein the window covering accumulates on and is supported by the bottom member as the bottom member is moved toward the top member, the improvement comprising:

• at least one consistent variable force spring drive motor for the window covering being coupled to the cord and wherein the spring drive motor comprises a coiled, elongate spring generally rectangular in cross-section which varies in thickness from a first end thereof to a second end thereof, wherein the spring force varies to substantially balance the combined weight of the bottom member and the covering it accumulates on the bottom member as the bottom member is moved toward the top member, and wherein the spring force is sufficient to maintain the bottom member at any position with respect to the top member.

A window covering of the type including a top member for supporting the window covering in a horizontal position and a bottom member, the window covering further including a cord means coupled to the bottom member and extending to the top member for supporting the bottom member as it is moved toward and away from the top member, wherein the window covering accumulates on and is supported by the bottom member as the bottom member is moved toward the top member, the improvement comprising:

• at least one consistent variable force spring drive motor for the window covering, said motor being coupled to the cord and wherein the spring drive motor comprises a coiled, elongate spring whose cross-section varies along its length between a first end thereof and a second end thereof, wherein the spring force varies to substantially balance the combined weight of the bottom member and the covering as it accumulates on the bottom member as the bottom member is moved toward the top member, and wherein the sprinq force is sufficient to maintain the bottom member at any position with respect to the top member.