US Patent 7523777 Roman shade

A roman shade comprises an operation box section for rotating a rotation gear as a driving ball chain (25) is pulled down; a rotation shaft (40) fitted into the rotation gear; a frame surrounding the operation box and the rotation shaft (40) and secured to a wall or ceiling; and a ball chain box section including an inside gear which is fitted around the rotation shaft (40), a driven ball chain (22) which has balls to be engaged into grooves defined on the inside gear so that the driven ball chain (22) is moved vertically as the inside gear is rotated, and a ball chain box in which the driven ball chain (22) is compiled without being entangled.