Double winding device for window shade without pull cord

Abstract

A double winding device for a window shade includes a head rail receiving first and second cord-winding seats. First and second movable seats are movably mounted between the first and second elastic cord-winding seats and respectively include first and second pulley units. A folding/unfolding cord is wound around the first and second pulley units and has two end sections extending through a bottom wall of the head rail and extending through two sides of a shade and fixed to a bottom of the shade. The first and second elastic cord-winding seats respectively include first and second elastic cord-winding spools. A first actuation cord is wound around the first elastic cord-winding spool and has a distal end fixed to the first movable seat. A second actuation cord is wound around the second elastic cord-winding spool and has a distal end fixed to the second movable seat.

1 . A double winding device for a window shade without a pull cord, with the double winding device comprising:
 a head rail including a compartment having a bottom wall, with first and second cord holes formed in the bottom wall of the compartment;   first and second movable seats movably mounted in the compartment, with the first movable seat including a first pulley unit, with the second movable seat including a second pulley unit, with a folding/unfolding cord wound around the first and second pulley units, with the folding/unfolding cord having two end sections respectively extending through the first and second cord holes and adapted to be extended through two sides of a shade and fixed to a bottom of the shade; and   first and second elastic cord-winding seats mounted in the compartment, with the first movable seat located between the first elastic cord-winding seat and the second movable seat, with the second movable seat located between the second elastic cord-winding seat and the first movable seat, with the first and second elastic cord-winding seats respectively including a first elastic cord-winding spool and a second elastic cord-winding spool, with a first actuation cord wound around the first elastic cord-winding spool and having a distal end fixed to the first movable seat, with a second actuation cord wound around the second elastic cord-winding spool and having a distal end fixed to the second movable seat.   
     
     
         2 . The double winding device as claimed in  claim 1 , with the first pulley unit including at least one roller. 
     
     
         3 . The double winding device as claimed in  claim 2 , with said at least one roller of the first pulley unit including three rollers. 
     
     
         4 . The double winding device as claimed in  claim 3 , with the first pulley unit further including an axle extending through the three rollers, with the three rollers being independently rotatable about the axle. 
     
     
         5 . The double winding device as claimed in  claim 1 , with the first movable seat including a body, with the body receiving the first pulley unit, with the head rail including two opposite vertical walls, with a ledge formed on each of the two vertical walls, with at least one first wheel rotatably mounted to each of two lateral sides of the body and rollable along one of the ledges of the head rail, with at least one second wheel rotatably mounted to each of the two lateral sides of the body and rollable along one of the two vertical walls. 
     
     
         6 . A double winding device for a window shade without a pull cord, with the double winding device comprising:
 a head rail including a compartment having a bottom wall, with first and second cord holes formed in the bottom wall of the compartment;   first and second movable seats movably mounted in the compartment, with the first movable seat including a first pulley unit, with the second movable seat including a second pulley unit, with a folding/unfolding cord wound around the first and second pulley units, with the folding/unfolding cord having two end sections respectively extending through the first and second cord holes and adapted to be extended through two sides of a shade and fixed to a bottom of the shade; and   an elastic cord-winding seat mounted in the compartment, with the first movable seat located between the first elastic cord-winding seat and the second movable seat, with the first elastic cord-winding seat including a first elastic cord-winding spool and a second elastic cord-winding spool, with a first actuation cord wound around the first elastic cord-winding spool and having a distal end fixed to the first movable seat, with a second actuation cord wound around the second elastic cord-winding spool and having a distal end fixed to the second movable seat.   
     
     
         7 . The double winding device as claimed in  claim 6 , with the first pulley unit including at least one roller. 
     
     
         8 . The double winding device as claimed in  claim 7 , with said at least one roller of the first pulley unit including three rollers. 
     
     
         9 . The double winding device as claimed in  claim 8 , with the first pulley unit further including an axle extending through the three rollers, with the three rollers being r independently rotatable about the axle. 
     
     
         10 . The double winding device as claimed in  claim 6 , with the first movable seat including a body, with the body receiving the first pulley unit, with the head rail including two opposite vertical walls, with a ledge formed on each of the two vertical walls, with at least one first wheel rotatably mounted to each of two lateral sides of the body and rollable along one of the ledges of the head rail, with at least one second wheel rotatably mounted to each of the two lateral sides of the body and rollable along one of the two vertical walls.