Patent ID: 9663987
Date: 2017-05-30
CPC Classifications: E06B

Claim:
1. A control system for a window shade, comprising: a suspension member; a first and a second casing portion; a rotary drum pivotally connected with the first casing portion and affixed with the suspension member, the rotary drum being rotatable to wind and unwind the suspension member; a torsion spring operable to bias the rotary drum in rotation for winding the suspension member, the torsion spring having a first and a second end, the second end being affixed with the second casing portion; a coupling member affixed with the second end of the torsion spring, the coupling member including a gear carrier and an axle sleeve affixed with each other, the torsion spring winding around the axle sleeve with the first end of the torsion spring affixed with the axle sleeve; a transmission axle disposed through the torsion spring, the transmission axle being rotationally coupled with the rotary drum; a central gear rotationally coupled with the transmission axle; a ring affixed with the second casing portion and having a plurality of teeth; and a plurality of planetary gears respectively connected pivotally with the gear carrier of the coupling member, the planetary gears being respectively meshed with the central gear and the teeth of the ring, wherein the gear carrier, the axle sleeve and the first end of the torsion spring are movable in unison at a speed different from a rotation speed of the transmission axle.