Motorized Venetian Blind System

A motorized venetian blind system for covering a window of a space, the blind system comprising:

• a blind drive unit;
• a bottom rail extending across the width of the window;
• a plurality of rectangular slats extending across the width of the window and spaced apart vertically between the blind drive unit and the bottom rail;
• a lift cord extending from the bottom rail through openings in the slats to the blind drive unit to provide for raising and lowering the bottom rail;
• a spool adapted to windingly receive the lift cord;
• a first motor coupled to the lift cord for winding and unwinding the lift cord around the spool to respectively raise and lower the bottom rail, the first motor coupled to a drive shaft and operable to cause the drive shaft to rotate;
• and
• a spring-wrap brake coupled between the drive shaft and the spool.

A motorized window treatment system for covering a window of a space, the window treatment system comprising:

• a drive unit;
• a window treatment comprising a bottom rail extending across the width of the window;
• a lift cord extending from the bottom rail to the drive unit to provide for raising and lowering the bottom rail;
• a spool adapted to windingly receive the lift cord;
• a first motor operatively coupled to the lift cord for winding and unwinding the lift cord around the spool to respectively raise and lower the bottom rail, the first motor coupled to a drive shaft and operable to cause the drive shaft to rotate;
• and
• a spring-wrap brake coupled between the drive shaft and the spool.

A spring-wrap brake assembly for use with a window treatment system having a window treatment operable to cover a window and a lift cord operable to raise and lower the window treatment, the spring-wrap brake comprising:

• a rotatable drive shaft;
• a spool adapted to windingly receive the lift cord;
• an outer coupler leg fixedly attached to the spool;
• an inner coupler leg fixedly attached to the drive shaft;
• a mandrel having an opening, the rotatable drive shaft received through the opening of the mandrel;
• and
• a coil spring wrapped around the mandrel, the coil spring having at least one tang operatively coupled to the inner coupler leg and the outer coupler leg;
• wherein when the drive shaft rotates, the inner coupler leg is operable to contact the least one tang to cause the spring to open such the drive shaft can cause the spool to rotate, and if an external force is applied to the spool, the outer coupler leg is operable to contact the at least one tang to cause the spring to tighten such that the spool cannot cause the drive shaft to rotate.