Patent Publication Number: US-2012032019-A1

Title: Activating device for cordless blind

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a cordless blind, and more specifically to an activating device attached to a cordless blind to raise or lower the cordless blind body without using an external pulling cord. 
     2. Description of the Related Art 
     Conventional window blinds generally include two types, i.e. a cord controlled type, which has an external cord to operate it, and a cordless controlled type, which is equipped with an activating device to raise or lower it, such as the one disclosed in Taiwan Pat. publication No. 263877 or Taiwan Pat. publication No. 322458. 
     However, in many instances in the prior art, the activating device has a complicated design and may cause an unsmooth operation, and therefore the issue of how to improve the structure of the conventional activating device for use in cooperation with the cordless blind and to enhance the efficiency of its use is always the manufacturer&#39;s concern. 
     SUMMARY OF THE INVENTION 
     It is one objective of the present invention to provide an activating device for a cordless blind, which has a simple structure, and is efficient in operation. 
     To achieve this objective of the present invention, the activating device provided by the present invention comprises a bracket, a driving reel rotatably connected with the bracket, a first transmission reel unit having a first transmission reel rotatably mounted with the bracket, and a cord wound around the first transmission reel and having two ends respectively connected with the driving reel and the first transmission reel such that the first transmission reel is rotatable along with the driving reel through the cord, and a second transmission reel unit having a second transmission reel rotatably connected with the bracket, and a constant torque spring wound around the second transmission reel and having two ends respectively connected with the first transmission reel and the second transmission reel such that the second transmission reel and the first transmission reel are rotated simultaneously through the constant torque spring. 
     When a cordless blind, in which the activating device of the present invention is installed, is gradually lowered, the first transmission reel is driven by the rotation of the driving reel to rotate through the cord, and meanwhile the second transmission reel is driven by the rotation of the first transmission reel through the constant torque spring until the cordless blind is fully extended. On the contrary, when the cordless blind is gradually lifted, the first transmission reel and the second transmission reel are rotated reversely by the rebound force generated by the constant torque spring, and meanwhile the driving reel is driven to rotate reversely by the first transmission reel thought the cord until the cordless blind is folded. 
     By means of the aforesaid design, the activating device of the present invention can control the elevation of the cordless blind through cooperation of the reels, the cord, and the constant torque spring, so as to have the advantages of simple structure and convenient operation. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is an exploded view of an activating device according to a preferred embodiment of the prevent invention; 
         FIG. 2  is a partial sectional view of a cordless blind in which an activating device according to the preferred embodiment of the prevent invention in installed, showing the window covering is folded; 
         FIGS. 3  is similar to  FIG. 2 , showing the window covering is unfolded; and 
         FIG. 4  is similar to  FIG. 3 , showing the window covering is gradually folded. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIGS. 1 and 2 , an activating device  20  in accordance with a preferred embodiment of the present invention is installed in a cordless blind  10 . In this embodiment, the cordless blind  10  includes a head rail  12 , a bottom rail  14  equipped with a plurality of balance weights (not shown), a window covering  16  disposed between the head rail  12  and the bottom rail  14 , and two strings  18  each passing through the window covering  16  and having one end connected with the bottom rail  14  and the other end received in the head end  12 . The activating device  20  comprises a bracket  30 , a driving reel  40 , a first transmission reel unit  50 , and a second transmission reel unit  60 . 
     The bracket  30  includes two retaining plates  32  spacedly fastened to the head rail  12 , and three shafts  34  fastened between the retaining plates  32 . 
     The driving reel  40  is rotatably sleeved on one of the shafts  34  of the bracket  30  and provided with two adjacent annular first grooves  42 . The strings  18  are connected with the driving reel  40  in a way that the strings  18  are respectively wound around one of the first grooves  42  of the driving reel  40 . 
     The first transmission reel unit  50  includes a first transmission reel  52  rotatably sleeved on another one of the shafts  34  of the bracket  30  and has an annular second groove  56 , and a cord  54  having one end fixedly connected with the driving reel  40  and the other end fixedly connected with the first transmission reel  52  such that the cord  54  can be wound around the second groove  56  of the first transmission reel  52 , as shown in  FIGS. 1 and 2 , or the driving reel  40 , as shown in  FIG. 3 , or both as shown in  FIG. 4 . 
     The second transmission reel unit  60  includes a second transmission reel  62  rotatably sleeved on the other one of the shafts  34  of the bracket  30  and provided with two annular third grooves  66 , and two constant torque springs  64  each having one end fixedly connected with the first transmission wheel  52  and the other end fixedly connected with the second transmission reel  62 , such that the two constant torque springs  64  can be respectively wound around the third grooves  66  of the second transmission reel  62  or the first transmission reel  52  or both. 
     The structure of the activating device  20  is described as above, and the cooperation of the activating device  20  of the present invention and the cordless blind  10  is outlined hereinafter. 
     When a user pulls downwards the bottom rail  14  to lower the window covering  16 , the driving reel  40  is rotated by the pulling force of the strings  18 , resulting in that the first transmission reel  52  will be driven to rotate through the cords  54 , which in turn will drive the second transmission reel  62  to rotate through the constant torque springs  64 . Once the window covering  16  is fully extended and the user stops from pulling the bottom rail  14 , the window covering  16  will stay in a state of static equilibrium because the total weight of the balance weights installed in the bottom rail  14  and the rebound force generated by the constant torque springs  64  are balanced, keeping the window covering  16  rested in a desired position, e.g. a fully extended position as shown in  FIG. 3 . 
     When the user pushes upwards the bottom rail  14  to retract the window covering  16 , as shown in  FIG. 4 , the first and second transmission reels  52  and  62  are driven to rotate reversely and synchronously by the sum of the rebound forces generated by the constant torque springs  64  and the pushing force applied by the user, and therefore the driving reel  40  can be driven to rotate reversely by the cord  54  during the rotation of the first transmission reel  52 , such that the strings  18  can be wound around the driving reel  40  to gradually fold the window covering  16 . When the window covering  16  is totally folded and the user stops from pushing the bottom rail  14 , the window covering  16  will stay in static equilibrium status since the total weight of the balance weights and the rebound force generated by the constant torque springs  64  are equal, keeping the window covering  16  rested in a desired position, e.g. a fully folded position as shown in  FIG. 2 . 
     Accordingly, the activating device of the present invention is configured to lift or lower the blind covering by the cooperation of the three reels, the cord, and the constant torque springs, that is to say, the activating device of the present invention has the advantages of simple structure and efficient operation. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.