Patent ID: 8336256

Claim:
A motorised drive system for driving a louvre assembly, the louvre assembly having a surround frame, first and second spaced apart operating bars positioned within the surround frame and where movement of the operating bars causes rotation of the louvres, the drive system comprising a motor adapted to be positioned within the surround frame, the motor operationally driving a drive shaft which is substantially horizontal when the drive system is fitted within the surround frame, a mounting member which is attached for rotation with the drive shaft, at least a first and a second attachment point spaced apart on the mounting member, a first link arm, a second link arm and a third link arm, the first link arm having a portion pivotally attached the first attachment point and another portion pivotally attached the first operating bar, the second link arm having a portion pivotally attached the second attachment point and another portion pivotally attached to a portion of the third link arm, the third link arm having another portion pivotally attached to the second operating bar wherein the second link arm and the third link arm can pivot relative to one another during at least part of the movement thereof that causes rotation of the louvres, wherein the distance between the portion of the first link arm attached to the first attachment point and the portion of the first link arm attached to the first operating bar comprises a first link length, the distance between the portion of the second link arm attached to the second attachment point and the portion of the third link arm attached to the second operating bar comprises a second link length, and the second link length varies and does not remain equal to the first link length throughout a range of movement of the drive system, but the relative pivoting between the second link arm and the third link arm allows this varying length to be taken up in a controlled manner as the louvres open and close.