Patent Number: 6,293,329

Title: Coil spring drive system and window cover

Abstract: A coil spring drive unit for window covers is disclosed, which comprises a coil spring drive and the combination whose elements are selected from (1) a band shift transmission which provides varying ratio power transfer as the cover is opened and closed; (2) gear means comprising various gear sets which provide frictional holding force and fixed power transfer ratios; and (3) a gear transmission which provides fixed ratio power transfer as the cover is opened or closed. The combination permits the coil spring drive torque to be tailored to the weight characteristics of the window cover such as a horizontal slat or pleated or box blind as the blind is opened and closed, and permits the length of the blind and the distance between the open and closed positions of the blind to be altered for a given rotational distance of the coil spring.

Inventors: Toti; Andrew J. (Modesto, CA)

Assignee:

International Classification: E06B 9/322 (20060101); E06B 9/28 (20060101); E06B 009/30 ()

Expiration Date: 09/25/2018