Patent Publication Number: US-7219710-B2

Title: Lifting mechanism for window shades

Description:
FIELD OF THE INVENTION 
     The present invention relates to shades and more particularly to an improved lifting mechanism mounted in a bottom slat of a window shade such that lifting or lowering of the shade will be smoother due to the support of the lifting mechanism. 
     BACKGROUND OF THE INVENTION 
     Conventionally, a shade is raised or lowered by pulling a lift cord. The lift cord is disposed externally of the shade. Thus, it is possible that the lift cord may tie children&#39;s necks for playing. This is very dangerous since the child may be hung accidentally. As such, the lift cord is typically concealed in a lifting mechanism in a lowest slat for safety reason. 
       FIG. 1  shows a window shade B incorporated a lifting mechanism A disclosed in U.S. Pat. No. 6,024,154. The lifting mechanism A is comprised of many components. As such, its components are mounted in a lower slat B 1 . This inevitably increases the size of the lower slat B 1 . Moreover, it increases the manufacturing cost, the weight of the lower slat B 1 , and winding force exerted on spring means of the lifting mechanism A, resulting in shortening the useful life of the shade. Thus, the need for improvement still exists. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a lifting mechanism mounted in a shade including a plurality of slats attached together and two lift cords, comprising a lightweight winding assembly, and a hoisting assembly fixedly attached to an inner surface of a lowest slat, the hoisting assembly comprising an elongated, hollow member of rectangular section including a bottom rectangular opening and two holes on its upper surface proximate both ends of the opening, and a channel of U-section fitted in the hollow member, the channel including a lengthwise groove and a plurality of spaced rollers across two raised walls of the groove, wherein the winding assembly is fixedly attached to an outer surface of the lowest slat, one lift cord has one end terminated at a left portion of a topmost slat and the other end terminated at the winding assembly by passing left portions of the slats, and the other lift cord has one end terminated at a right portion of the topmost slat and the other end terminated at the winding assembly by passing right portions of the slats. By mounting the lifting mechanism in the shade, lifting or lowering of the shade will be smoother due to the support of the hoisting mechanism. 
     The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a window shade incorporated a lifting mechanism disclosed in U.S. Pat. No. 6,024,154. 
         FIG. 2  is an exploded view of a hoisting assembly to be mounted in a lifting mechanism for shade according to the present invention. 
         FIG. 3  is a perspective view of a shade to be assembled with the hoisting assembly and a winding assembly of the present invention in its lowest slat. 
         FIG. 4  is a front view of the assembled shade of  FIG. 3 . 
         FIG. 5  is a side view of the shade of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 2 ,  3 , and  4 , a shade  2  incorporated with a lifting mechanism (including elements  1  and  3 ) is constructed in accordance with a preferred embodiment of the present invention. The lifting mechanism comprises a small, lightweight winding assembly  3  and a hoisting assembly  1  attached to an inner surface of a bottom slat  200  in a bottom  20  of the shade  2  by adhesive. The hoisting assembly  1  comprises an elongated, hollow member  10  of rectangular section including a bottom rectangular opening  11  and two holes  13  on an upper surface of the hollow member  10  proximate both ends of the opening  11 , and a channel  12  of U-section fitted in the hollow member  10 , the channel  12  including a lengthwise groove  120  and a plurality of spaced rollers  121  and  122  across two raised walls of the groove  120 . Each of two lift cords  21  and  22  has one end terminated at a left (or right) portion of a top slat  23  and the other end terminated at the winding assembly  3  by passing left (or right) portions of a plurality of slats  23 , the left (or right) hole  13 , and left rollers  121  and  122  (or right rollers  121  and  122 ). Note that the winding assembly  3  is attached to an outer surface of the bottom slat  200  in the bottom  20  of the shade  2  by adhesive. 
     By configuring as above, the hoisting assembly  1  is able to provide an appropriate weight to the slats  23 . As such, referring to  FIG. 5 , lifting or lowering of the shade  2  by pulling the lift cords  21  and  22  will be smoother without causing tilt of the slats  23 . 
     While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.