Patent ID: 6659156
Filing Date: 2003-12-09
Classification: E06B,Y10S

Abstract:
A screw transmission mechanism mounted in a Venetian blind for controlling lifting of slats and bottom rail of the Venetian blind and tilting of slats of the Venetian blind, comprising at least one cord roll-up unit and a driving unit adapted to drive said at least one cord roll-up unit, wherein said at least one cord roll-up unit each comprises:an amplitude modulation set, said amplitude modulation set comprising a support, an amplitude modulation life cord connected to the slats and bottom rail of the Venetian blind and adapted to lift and lower the slats and bottom rail of the Venetian blind, and an amplitude modulation wheel threaded into said support and coupled to said driving unit for free rotation and axial movement relative to said support to roll up and let off said amplitude modulation life cord upon operation of said driving unit, said amplitude modulation wheel comprising a longitudinal groove; a frequency modulation set, said frequency modulation set comprising a frequency modulation lift cord adapted to tilt the slats of the Venetian blind and a frequency modulation wheel sleeved onto said amplitude modulation wheel and adapted to roll up and let off said frequency modulation lift cord, said frequency modulation wheel comprising a notch; and a linkage, said linkage comprising a link mounted in the groove of said amplitude modulation wheel and the notch of said frequency modulation wheel to couple said frequency modulation wheel to s aid amplitude modulation wheel for synchronous rotation, and a stop block adapted to limit the angle of rotation of said frequency modulation wheel and to force said link away from said frequency modulation wheel when said amplitude modulation wheel is rotated to a predetermined position.