Window covering height adjustment apparatus and method using multiple interconnected cord winding rotors

摘要

Apparatus for raising and lowering a window shade, comprising first and second lines movable together to raise and lower the shade, a third line, which is a control line, and first, second and third rotors to which the first and second and third lines are respectively connected, whereby when the third line is displaced, the third rotor rotates to effect rotation of the first and second rotors to displace the first and second dines to raise or lower the shade.