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Folding device for cordless blind

  • US 20070261798A1
  • Filed: 01/26/2007
  • Published: 11/15/2007
  • Est. Priority Date: 05/11/2006
  • Status: Abandoned Application
First Claim
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1. A folding device for a cordless blind, comprising a string spool and a force-return mechanism, the force-return mechanism including a transmission shaft coupled to the string spool to turn therewith, the force-return mechanism further including a smaller bevel gear connected to the transmission shaft, a larger bevel gear meshing with the smaller bevel gear and being rotatable about a vertical axis, a first bobbin being coupled to the larger bevel gear to turn therewith, the force-return mechanism further including a second bobbin and a spiral spring having two ends respectively engaged with the first and second bobbins such that winding movement of the spiral spring about a rotating axis of the first bobbin causes unwinding movement of the spiral spring about a rotating axis of the second bobbin and that unwinding movement of the spiral spring about the rotating axis of the first bobbin causes winding movement of the spiral spring about the rotating axis of the second bobbin, the first bobbin including a top end with a gear, the second bobbin including a top end with a gear meshed with the gear of the first bobbin to assist in transmission between the first and second bobbins, the larger bevel gear and the smaller bevel gear having a gear ratio therebetween to allow high rotating speed of the string spool and low rotating speed of the larger bevel gear such that the string spool is turned with a small winding/unwinding extent of the spiral spring, with the smaller bevel gear pressing against the larger bevel gear in a vertical direction and cooperating with a weight of a shade of a blind to provide an optional braking effect for the shade in a vertical direction.

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