Patent Publication Number: US-2011061823-A1

Title: Counterbalanced blind

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a blind, and more particularly to a counterbalanced blind that can be operated easily without a pull string. 
     2. Description of Related Art 
     For shielding off sunshine or external light, windows are usually provided with blinds or shades. A conventional blind generally has a top frame, a bottom bar, a shade and a control device. The top frame is mounted securely on a wall or a ceiling. Two sides of the shade are respectively fastened to the top frame and the bottom bar. The control device is mounted in the top frame and has a pull string that is hung beside the top frame. When the pull string is parallel to the blind, the control device is locked and the shade is held at a predetermined height. When the pull string is obliquely, the control device is released and the bottom bar is free to move and the shade may be concertinaed or spread out to control amount of light entering a room. 
     However, when the top frame is hung relatively high compared to a person controlling the blinds, for example when wheelchair users or children are operating the blind or when the blind is hung high due to a large window, high ceiling or use on stairwells, positioning the pull string sufficiently obliquely to release the bottom bar and the shade may be difficult. Furthermore, the pull string may be dangerous to young children and pets, especially threat by strangulation or entanglement. 
     Therefore, the present invention provides a counterbalanced blind to overcome the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide a counterbalanced blind that can be operated easily without a pull string. 
     The counterbalanced blind has a top frame, a bottom bar, a shade mounted between the top frame and the bottom bar, a reel device, two roller devices and two cords. The reel device is mounted in the top frame, and the two roller devices are mounted on the opposite side of the reel device in the top frame. The cords are wound and fastened in the reel device, respectively extend in opposite directions to the roller devices, pass downward through the shade and are fastened on the bottom bar. The bottom bar can be raised or lowered, and position of the bottom bar is retained after releasing the bottom bar. 
     Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a counterbalanced blind in accordance with the present invention; 
         FIG. 2  is a sectional front view of the counterbalanced blind in  FIG. 1 ; 
         FIG. 3  is a perspective view of a reel device in accordance with the present invention; 
         FIG. 4  is a sectional front view of the roller device in  FIG. 2 ; 
         FIG. 5  is a sectional front view of the counterbalanced blind in a lowered status; 
         FIG. 6  is a sectional front view of the counterbalanced blind in a raised status. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     With reference to  FIGS. 1 to 4 , a counterbalanced blind in accordance with the present invention comprises a top frame ( 10 ), a bottom bar ( 20 ), a shade ( 30 ), two roller devices ( 4 ), a reel device ( 5 ) and two cords ( 60 ). 
     The top frame ( 10 ) is mounted on walls or ceilings, especially adjacent to windows. With reference to  FIGS. 1 and 2 , the shade ( 30 ) is mounted between the top frame ( 10 ) and the bottom bar ( 20 ). 
     The two roller devices ( 4 ) are mounted separately in the top frame ( 10 ), and each roller device ( 4 ) has a first roller ( 41 ), a second roller ( 42 ), and an optional bracket ( 40 ). The first roller ( 41 ) and the second roller ( 42 ) are rotatably mounted on the bracket ( 40 ) that is mounted in the top frame ( 10 ). 
     With further reference to  FIG. 3 , the reel device ( 5 ) is mounted between the two roller devices ( 4 ) in the top frame ( 10 ) and comprises a first reel ( 51 ), a second reel ( 52 ), a resilient member ( 53 ) and an optional casing ( 50 ). The first reel ( 51 ) and the second reel ( 52 ) are mounted rotatably in the casing ( 50 ). The first reel ( 51 ) has a first gear ( 511 ) formed thereon, the second reel ( 52 ) has a second gear ( 521 ) formed thereon and meshing with the first gear ( 511 ) to provide synchronous rotation. The resilient member ( 53 ) may be a rotary spring and connects the first reel ( 51 ) with the second reel ( 52 ). 
     With reference to  FIG. 4 , one of the cords ( 60 ) is fastened and wound on the first reel ( 51 ), and the other cord ( 60 ) fastened and wound on the second reel ( 52 ). The cords ( 60 ) respectively extend in opposite directions through the roller devices ( 4 ). Each cord ( 60 ) is wound on the first roller ( 41 ) and the second roller ( 42 ), then turned to the first roller ( 41 ) to counterbalance forces added on the roller device ( 4 ) and extends downward through the shade ( 30 ) to be fastened on the bottom bar ( 20 ). 
     With reference to  FIGS. 5 and 6 , users can raise or lower the bottom bar ( 20 ) to simultaneously concertina or spread out the shade ( 30 ). When the counterbalanced blind is operated, the cords ( 60 ) are pulled or released the same distance in opposite directions because the first gear ( 511 ) meshes with the second gear ( 521 ), so the bottom bar ( 20 ) maintains balanced. In addition, the bottom bar ( 20 ) is held at a predetermined height when users stop operating it, because the cord ( 60 ) wound on each roller device ( 4 ) counterbalances the forces added on the roller device ( 4 ), so the blind can be operated more easily without a pull string and for improved safety. 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.