Self-raising window covering

Abstract

The present invention relates to a self-raising window covering and a control mechanism for the window covering. In particular, the window covering includes a drive unit, such as constant force spring, that is adapted to apply a substantially constant rotational force on the drive axle. A cord winding assembly is coaxially mounted on the drive axle, and includes at least one winding drum operatively connected to a second end of the raising cord and having a tapered portion, as well as a rotatable positioning member for moving the cord winding assembly laterally along the drive axle upon rotation of the positioning member. The cord winding assembly is adapted to translate the rotational force on the drive axle to a raising force on the raising cord, wherein the raising force is greater than a downward force exerted by the shade element and bottom rail throughout the range of opening and closing. A clutch member or locking member is also operatively connected with the axle and adapted to releasably lock the drive axle in a desired position.

1 . A window covering comprising:
 a head rail;   a shade element including a top end and a bottom end, wherein the top end is secured with the head rail, and the shade element is vertically suspended from the head rail and suspended at a stationary first position;   a bottom element secured with the bottom end of the shade element;   a raising member connecting a control mechanism and the bottom element;   the control mechanism including a drive unit that exerts a raising force in a first direction, the raising force being selectively communicated to the raising member and is sufficient to raise the bottom element from the first position to a second position and to stack increasing portions of the shade element on the bottom element, the control mechanism further including an actuator having a locked condition and a release condition such that when in the locked condition the actuator counteracts application of the raising force on the raising member, and when the actuator is in the release condition the raising force is communicated to the raising member to raise the bottom element; and   the actuator is moved from the locked condition to the release condition by communication of a second force to the drive unit, the second force being opposite in direction to the raising force in the first direction.   
     
     
         2 . The window covering of  claim 1 , wherein the bottom element is stationary in the first position and the actuator is in the locked condition. 
     
     
         3 . The window covering of  claim 1 , wherein the bottom element is movable from a position vertically higher than the first position to the first position by a downward force on the bottom element, wherein after release of the downward force the actuator switch member is in the locked position. 
     
     
         4 . The window covering of  claim 1 , wherein:
 the raising member is a cord element having a distal end connected with the bottom element;   the control mechanism further comprises a cord winding assembly configured to wind and unwind the cord element;   the drive unit continuously applies a spring force for rotating the cord winding assembly in the first direction that winds the cord element; and   the actuator is a clutch operable to selectively lock rotation of the cord winding assembly.   
     
     
         5 . The window covering of  claim 4 , wherein the clutch member permits rotation of the cord winding assembly in a direction for unwinding the cord element when a downward force is applied on the bottom element. 
     
     
         6 . The window covering of  claim 4 , wherein the drive unit continuously applies the spring force on a drive axle coupled with the clutch member and the cord winding assembly. 
     
     
         7 . The window covering of  claim 6 , wherein the clutch member selectively locks rotation of the drive axle against the spring force of the drive spring unit. 
     
     
         8 . The window covering of  claim 1 , wherein the shade element includes a collapsible structure. 
     
     
         9 . A window covering comprising:
 a head rail;   a shade element vertically suspended from the head rail;   a bottom element secured with a bottom end of the shade element, the bottom element being suspended from the head rail at a first position; and   a control mechanism operatively connected to the bottom element by a raising member, wherein the control member selectively retracts the raising member and raises the bottom element from a first position to a second position in response to a downward displacement of the bottom element from the first position sufficient to disengage an actuator, and wherein increasing portions of the shade element are stacked on the bottom element as the bottom element is raised.   
     
     
         10 . The window covering of  claim 9 , wherein the raising member is a cord, and wherein the control mechanism comprises:
 a spring unit;   a cord winding assembly coupled with the bottom element via the cord; and   the actuator is a clutch member configured to block rotation of the cord winding assembly when the bottom element is in the first position, and enable rotation of the cord winding assembly in response to the downward displacement of the bottom element from the first position.   
     
     
         11 . The window covering of  claim 10 , wherein the spring unit continuously applies a spring force to rotate the cord winding assembly in a first direction that winds the cord element. 
     
     
         12 . The window covering of  claim 10 , wherein the clutch member permits rotation of the cord winding assembly in a second direction for unwinding the cord element when a downward pulling force is applied on the bottom element. 
     
     
         13 . The window covering of  claim 10 , wherein the clutch member and the cord winding assembly are coupled with a drive axle. 
     
     
         14 . The window covering of  claim 13 , wherein the spring unit applies the spring force on the drive axle. 
     
     
         15 . The window covering of  claim 14 , wherein the clutch member selectively blocks rotation of the drive axle against the spring force. 
     
     
         16 . The window covering of  claim 9 , wherein the shade element includes a collapsible structure. 
     
     
         17 . A method of operating a window covering, wherein the window covering comprises a shade element vertically suspended from a head rail, a bottom element secured with a bottom end of the shade element, and a control mechanism adapted to apply a spring force in a first direction to selectively raise the bottom element and to stack increasing portions of the shade element on the bottom element, the method comprising:
 applying a downward force on the bottom element and moving the bottom element from a stationary first position to a release position lower than the first position such that the downward force is communicated to the control mechanism and acts in an opposite direction to the spring force in the first direction; and   discontinuing application of the downward force on the bottom element when the bottom element is at the release position; and   permitting the spring force of the control mechanism to raise the bottom element free of a user applied upward force on the bottom element and such that at least a portion of the shade element is stacked on the bottom element.   
     
     
         18 . The method of  claim 17 , wherein the shade element includes a collapsible structure. 
     
     
         19 . The method of  claim 17 , further comprising applying a downward force on the bottom element after permitting the spring force of the control mechanism to raise the bottom element and causing the control mechanism to block further raising of the bottom element.