Counterbalanced blind

Abstract

A 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 will be retained after releasing the bottom bar.

What is claimed is: 
     
         1 . A counterbalanced blind comprising:
 a top frame ( 10 );   a bottom bar ( 20 );   a shade ( 30 ) mounted between the top frame ( 10 ) and the bottom bar ( 20 );   two roller devices ( 4 ) mounted separately in the top frame ( 10 ) and each roller device ( 4 ) having
 a first roller ( 41 ) rotatably mounted in the top frame ( 10 ); 
 a second roller ( 42 ) rotatably mounted in the top frame ( 10 ); 
   a reel device ( 5 ) mounted between the two roller devices ( 4 ) in the top frame ( 10 ) and comprising
 a first reel ( 51 ) rotatably mounted in the top frame ( 10 ) and having a first gear ( 511 ) formed thereon; 
 a second reel ( 52 ) rotatably mounted in the top frame ( 10 ), having a second gear ( 521 ) formed thereon, and the second gear ( 521 ) meshing with the first gear ( 511 ); 
 a resilient member ( 53 ) mounted on the first reel ( 51 ) and connecting the first reel ( 51 ) with the second reel ( 52 ); and 
   two cords ( 60 ), one of the cords ( 60 ) 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 extending in opposite directions through the roller devices ( 4 ), each cord ( 60 ) wound on the first roller ( 41 ) and the second roller ( 42 ) of the roller device ( 4 ), passing through the shade ( 30 ) and fastened to the bottom bar ( 20 ) to counterbalance forces added on the roller device ( 4 ).   
     
     
         2 . The counterbalanced blind as claimed in  claim 1 , wherein each cord ( 60 ) is wound on the first roller ( 41 ), the second roller ( 42 ), then turns to the first roller ( 41 ) to counterbalance forces added on the roller device ( 4 ), and extends downward to be fastened on the bottom bar ( 20 ). 
     
     
         3 . The counterbalanced blind as claimed in  claim 1 , wherein the reel device ( 5 ) comprises a casing mounted in the top frame ( 10 ), and the first reel ( 51 ) and the second reel ( 52 ) are mounted rotatably in the casing ( 50 ). 
     
     
         4 . The counterbalanced blind as claimed in  claim 2 , wherein the reel device ( 5 ) comprises a casing mounted in the top frame ( 10 ), and the first reel ( 51 ) and the second reel ( 52 ) are mounted rotatably in the casing ( 50 ). 
     
     
         5 . The counterbalanced blind as claimed in  claim 1 , wherein each roller device ( 4 ) comprises a bracket ( 40 ) mounted in the top frame ( 10 ), and the first roller ( 41 ) and the second roller ( 42 ) are mounted rotatably on the bracket ( 40 ). 
     
     
         6 . The counterbalanced blind as claimed in  claim 2 , wherein each roller device ( 4 ) comprises a bracket ( 40 ) mounted in the top frame ( 10 ), and the first roller ( 41 ) and the second roller ( 42 ) are mounted rotatably on the bracket ( 40 ). 
     
     
         7 . The counterbalanced blind as claimed in  claim 3 , wherein each roller device ( 4 ) comprises a bracket ( 40 ) mounted in the top frame ( 10 ), and the first roller ( 41 ) and the second roller ( 42 ) are mounted rotatably on the bracket ( 40 ). 
     
     
         8 . The counterbalanced blind as claimed in  claim 4 , wherein each roller device ( 4 ) comprises a bracket ( 40 ) mounted in the top frame ( 10 ), and the first roller ( 41 ) and the second roller ( 42 ) are mounted rotatably on the bracket ( 40 ).