Limiting mechanism for lifting and lowering blind

Abstract

The present invention relates to a limiting mechanism for lifting and lowering a blind. The limiting mechanism includes a carrier; a resilient unit movably disposed at an end of the carrier; a recoiling roller movably disposed in the carrier and positioned proximate to the resilient unit; and a tractional unit movably disposed in the carrier and driven by the recoiling roller. The limiting mechanism is integrated into a blind body when in use, so as for a shade to be lifted or lowered when an external force is exerted thereon by a user, wherein the lifting or lowering of the shade is effectuated by the resilient unit, the recoiling roller, and the tractional unit in conjunction with the external force exerted by the user, so as to dispense with a tractional cord and enhance ease of use and use safety.

What is claimed is: 
     
         1 . A limiting mechanism for lifting and lowering a blind, comprising:
 a carrier;   a resilient unit movably disposed at an end of the carrier;   a recoiling roller movably disposed in the carrier and positioned proximate to the resilient unit; and   a tractional unit movably disposed in the carrier and driven by the recoiling roller.   
     
     
         2 . The limiting mechanism of  claim 1 , wherein the carrier is a frame. 
     
     
         3 . The limiting mechanism of  claim 1 , wherein the resilient unit further comprises a reel and a plurality of constant force springs, the reel having at least two spooling portions, and the constant force springs being disposed on the spooling portions, respectively, wherein the constant force springs each have an end coupled to a corresponding one of the spooling portions and another end coupled to the recoiling roller. 
     
     
         4 . The limiting mechanism of  claim 1 , wherein a first gear member is disposed on a side of the recoiling roller and configured to drive the tractional unit. 
     
     
         5 . The limiting mechanism of  claim 1 , wherein the tractional unit further comprises a cord roller, a second gear member, and a plurality of cords, the second gear member being disposed on a side of the cord roller and configured to drive the recoiling roller, and the cords being windingly coupled to the cord roller. 
     
     
         6 . The limiting mechanism of  claim 5 , wherein a plurality of cord grooves are provided on the cord roller and configured to receive the cords, respectively.