Abstract:
A blind lift rod control lock includes a housing having an axle hole, a rotating member revolvably mounted in the axle hole of the housing, the rotating member having a non-circular through hole, which receives a lift rod for enabling the rotating member to be synchronously rotated with the lift rod, a reverse ratchet, and a forward ratchet, and a locking mechanism. The locking mechanism has a follower member, a first hooked portion adapted to engage the reverse ratchet, and a second hooked portion adapted to engage the forward ratchet. The follower member is selectively controlled to force the first hooked portion into engagement with the reverse ratchet or the second hooked portion into engagement with the forward ratchet.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to blinds and, more particularly, to a blind lift rod control lock for use in a blind assembly to lock the lift rod.  
           [0003]    2. Description of the Related Art  
           [0004]    A blind with hidden lift cord is known comprised of a headrail, a bottom rail, a set of blind slats, two lift cords, a frequency modulation mechanism, and a receiving mechanism. The frequency modulation mechanism and the receiving mechanism are installed in the headrail. The blind slats connected in parallel between the headrail and the bottom rail by ladder tapes. The lift cords each have one end connected to the receiving mechanism and the other end inserted through the blind slats and fastened to the bottom rail. The frequency modulation mechanism controls the tilting angle of the blind slats to regulate the amount of light passing through the blind. The receiving mechanism comprises a reversing spring, a lift rod, and two bobbins. The reversing spring is adapted to reverse the lift rod after the lift rod being rotated. The lift rod is rotated clockwise when the user lifting the bottom rail toward the headrail, or counter-clockwise when the user pulling the bottom rail downwards. The bobbins are fixedly mounted on the lift rod for synchronous rotation to roll up or let off the lift cords, for enabling the blind slats to be received or extended out. Normally, the reversing power of the reversing spring must be properly controlled. Excessive reversing power of the reversing spring may cause the lift rod to roll up the lift cords unexpectedly after the blind has been fully extended out, or may be unable to let the bottom rail be stopped at the desired elevation. Insufficient reversing power of the reversing spring causes the reversing spring unable to rotate the lift rod to the desired angular position when the user lifting the bottom rail of the blind. During lifting of the bottom rail by the lift cords, the reversing power of the reversing spring must conquer the gravity weight of the bottom rail and the weight of the blind slats being received at the bottom rail. Insufficient reversing power of the reversing spring cannot bear the total weight of the bottom rail and the blind slats, and the bottom rail may be stopped in position lower than the expected elevation. Therefore, the set value of the reversing power of the reversing spring determines the smoothness of the receiving or extending operation of the blind. Further, the reversing spring starts to wear quickly with use, resulting in an elastic fatigue. In order to prolong the service life of the reversing spring, the ends of the reversing spring may be made relatively wider or thicker. However, this improvement cannot completely eliminate the reversing spring from elastic fatigue.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention has been accomplished to provide a blind lift rod control lock, which eliminates the aforesaid drawbacks. It is therefore the main object of the present invention to provide a blind lift rod control lock, which locks the lift rod of the blind positively in position to accurately hold the bottom rail of the blind at the desired elevation.  
           [0006]    To achieve this object of the present invention, the blind lift rod control block is coupled to the lift rod of a blind and adapted to lock the lift rod of the blind, comprising a housing having an axle hole, a rotating member revolvably mounted in the axle hole of the housing, the rotating member having a non-circular through hole, which receives the lift rod for enabling the rotating member to be synchronously rotated with the lift rod, a reverse ratchet extended around the non-circular through hole and a forward ratchet extended around the non-circular through hole; and a locking mechanism having a follower member, a first hooked portion adapted to engage the reverse ratchet, and a second hooked portion adapted to engage the forward ratchet, the follower member being selectively controlled to force the first hooked portion into engagement with the reverse ratchet or the second hooked portion into engagement with the forward ratchet. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a perspective view of a blind lift rod control lock according to the present invention.  
         [0008]    [0008]FIG. 2 is an exploded view of the blind lift rod control lock according to the present invention.  
         [0009]    [0009]FIG. 3 is a front view of the blind lift rod control lock according to the present invention, showing the follower member moved to the second position.  
         [0010]    [0010]FIG. 4 is a rear view of the blind lift rod control lock according to the present invention, showing the first stop face of the locating ring stopped at the first stop face of the housing.  
         [0011]    [0011]FIG. 5 is a side view, partially in section, of the blind lift rod control lock according to the present invention.  
         [0012]    [0012]FIG. 6 is a schematic drawing showing the blind lift rod control lock used with a frequency modulation mechanism according to the present invention.  
         [0013]    [0013]FIG. 7 is a schematic drawing showing the blind lift rod control lock used with a switching mechanism according to the present invention.  
         [0014]    [0014]FIG. 8 is a front view, partially in section, of the blind lift rod control lock, showing the follower member moved to the first position according to the present invention.  
         [0015]    [0015]FIG. 9 is another rear view of the blind lift rod control lock according to the present invention, showing the second stop face of the locating ring stopped at the second stop face of the housing. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Referring to Referring to FIG. 1, a blind lift rod control lock  100  is installed in the headrail of the blind (not shown) and coupled to the lift rod  1  of the blind. The lift rod  1  is rotated clockwise or counter-clockwise subject to the receiving or extending action of the blind.  
         [0017]    Referring to FIGS.  2 ˜ 5 , the blind lift rod control lock  100  comprises a housing  10 , a rotating member  20 , and a locking mechanism  30 .  
         [0018]    The housing  10  has a front side  11 , a back side  12 , an axle hole  13 , and a through hole  14 . The front side  11  has a flat first step  111  and a flat second step  112 . The first step  111  protrudes from the second step  112 . The back side  12  has a top protruding block  121 . The top protruding block  121  has a bottom side forming a first stop face  122  and a second stop face  123 . The axle hole  13  extends through the housing  10 , having one end terminating in an opening  113  in the front side  11  of the housing  10  between the first step  111  and the second step  112  and the other end cut through the back side  12 . The through hole  14  extends through the housing  10  in parallel to the axle hole  13 , having one end cut through the second step  112  and the other end cut through the back side  12  of the housing  10 . The first stop face  122  and the second stop face  123  are disposed at two sides of the through hole  14 .  
         [0019]    The rotating member  20  is a cylindrical member inserted into the axle hole  13  for free rotation without axial displacement, having a rectangular axial through hole  21  coaxial to the axle hole  13 . The aforesaid lift rod  1  is a rectangular rod member fitted into the rectangular axial through hole  21  of the rotating member  20 . The rotating member  20  has one end extended out of the front side  11  of the housing  10  and fixedly provided with a forward ratchet  22  and a reverse ratchet  23  in front of the forward ratchet  22 . The forward ratchet  22  is disposed outside the second step  112  and partially protruding over the opening  113 . The reverse ratchet  23  protrudes over the first step  111 .  
         [0020]    The locking mechanism  30  comprises a first pawl  31 , a first spring member  32 , a second pawl  33 , a second spring member  34 , two pivot bolts  35 , a follower member  36 , an axle bush  37 , a locating ring  38 , and a tilt rod  39 .  
         [0021]    The first pawl  31  is pivoted to the first step  111  by one of the pivot bolts  35 , having two ends respectively terminating in a first hooked portion  311  and a first contact portion  312  far from the corresponding pivot bolt  35  at two sides. The first spring member  32  is a spring plate, having one end fixedly fastened to the housing  10  and the other end stopped against the first pawl  31 . The first spring member  32  imparts a downward pressure to the first pawl  31 , forcing the hooked portion  311  of the first pawl  31  into engagement with the reverse ratchet  23 . The second pawl  33  is pivoted to the second step  112  by the other of the pivot bolts  35 , having two ends respectively terminating in a second hooked portion  331  and a second contact portion  332  far from the corresponding pivot bolt  35  at two sides. As illustrated in FIG. 1, the first pawl  31  and the second pawl  33  do not interfere with each other, and the contact portion  312  of the first pawl  31  is supported on the contact portion  332  of the second pawl  33 . The second spring member  34  is a spring plate, having one end fixedly fastened to the housing  10  and the other end stopped against the second pawl  33 . The second spring member  34  imparts a downward pressure to the second pawl  33 , forcing the hooked portion  331  of the second pawl  33  into engagement with the forward ratchet  22 .  
         [0022]    The follower member  36  is a cylindrical member inserted through the through hole  14  and rotatable between a first position P 1  and a second position P 2  (this will be described further), having an axial center through hole  361  coaxial to the through hole  14 , a first bearing portion  362  disposed around the axial center through hole  361  at one end outside the front side  11  of the housing  10  corresponding to the contact portion  312  of the first pawl  31 , and a second bearing portion  363  disposed around the axial center through hole  361  behind the first bearing portion  362  corresponding to the contact portion  332  of the second pawl  33 . The first bearing portion  362  and the second bearing portion  363  are concentrically arranged cams that protrude in different directions.  
         [0023]    The axle bush  37  is inserted into the axial center through hole  361  of the follower member  36 , having a rectangular axial center through hole  371  coaxial to the axial center through hole  361  of the follower member  36 . The locating ring  38  is fastened to the rear end of the axle bush  37  outside the back side  12  of the housing  10 , having a first stop face  381  and a second stop face  382  corresponding to the first stop face  122  and second stop face  123  of the top protruding block  121  of the housing  10 .  
         [0024]    The tilt rod  39  is a rectangular rod fitted into the rectangular axial center through hole  371  of the axle bush  37  and rotatable clockwise/counter-clockwise by an external rotary driving force. Rotating the tilt rod  39  causes the axle bush  37 , the follower member  36  and the locating ring  38  to be rotated with the tilt rod  39 . It is to be understood that the locating ring  38  is not fixedly fastened to the follower member  36 . When one stop face (the first stop face  381  or second stop face  382 ) of the locating ring  38  stopped against one stop face (the first stop face  122  or second stop face  123 ) of the top protruding block  121  of the housing  10  during rotary motion of the tilt rod  39 , one bearing portion (the first bearing portion  362  or second bearing portion  363 ) of the follower member  36  is stopped against the corresponding pawl (the first pawl  31  or the second pawl  33 ), and at this time the axle bush  37  is rotated with the tilt rod  39  relative to the follower member  36  and the locating ring  38 .  
         [0025]    The above statement explains the structure of the parts of the blind lift rod control lock  100  and their relative positioning. The functioning and achievements of the blind lift rod control lock  100  are outlined hereinafter.  
         [0026]    At first, the clockwise or counter-clockwise rotating control of the tilt rod  39  is explained. As shown in FIG. 6, the tilt rod  39  to which the axle bush  37  is coupled is a member of the frequency modulation mechanism  2  of the blind adapted to control the tilting angle of the blind slats. During frequency modulation, the follower member  36  and the locating ring  38  are respectively stopped against the corresponding pawl  31  or  33  and the housing  10  and prohibited from rotary motion at an early stage, however the tilt rod  39  and the axle bush  37  are continuously rotated to tilt the blind slats of the blind.  
         [0027]    In the aforesaid example, the frequency modulation mechanism  2  drives the tilt rod  39 . Alternatively, a switching mechanism  200  may be used and coupled between the blind lift rod control lock  100  and the frequency modulation mechanism  2 . The switching mechanism  200  comprises a coupling device  201  coupled to the tilt rod  39 , a left lift cord  202 , and a right lift cord  203 . The lift cords  202  and  203  each have one end fixedly connected to the coupling deice  201  and the other end suspending outside the headrail of the blind. The user can pull the left lift cord  202  to rotate the tilt rod  39  clockwise, or pull the right lift cord  203  to rotate the tilt rod  39  counter-clockwise. When pulling the left lift cord  202  or the right lift cord  203 , the follower member  36  and the locating ring  38  are simultaneously rotated with the tilt rod  39  and the axle bush  37  clockwise or counter-clockwise.  
         [0028]    Alternatively, the tilt rod  39  can be made independent of the frequency modulation mechanism  2 , enabling the switching mechanism  200  to control the direction of rotation of the tilt rod  39 .  
         [0029]    The locking control of the blind lift rod control lock  100  on the lift rod  1  is outlined hereinafter. FIG. 3 illustrates the tilt rod  39  rotated clockwise. At this time, as shown in FIG. 4, the first stop face  381  of the locating ring  38  is stopped at the first stop face  122  of the housing  10 , and the second bearing portion  363  of the follower member  36  is stopped against the contact portion  332  of the second pawl  33 , thereby causing the follower member  36  to be held in the second position P 2 . When the follower member  36  held in the second position P 2 , the hooked portion  331  of the second pawl  33  is disengaged from the forward ratchet  22 , and the hooked portion  311  of the first pawl  31  is forced by the first spring member  32  into engagement with the reverse ratchet  23  to stop the lift rod  1  from reverse rotation by the reversing spring of the blind (not shown), and therefore the lift rod  1  is locked, holding the bottom rail of the blind at the desired elevation.  
         [0030]    [0030]FIGS. 8 and 9 show the status of the blind lift rod control lock  100  after reversed rotation of the tilt rod  39 . At this time, the second stop face  382  of the locating ring  38  is stopped at the second stop face  123  of the housing  10 , and the first bearing portion  362  of the follower member  36  is stopped against the contact portion  312  of the first pawl  31 , thereby causing the follower member  36  to be held in the first position P 1 . When the follower member  36  held in the first position P 1 , the hooked portion  311  of the first pawl  31  is disengaged from the reverse ratchet  23 , and the hooked portion  331  of the second pawl  33  is forced by the second spring member  34  into engagement with the forward ratchet  22  to stop the lift rod  1  from rotation, and therefore the lift rod  1  is locked, holding the bottom rail of the blind at the desired elevation.  
         [0031]    The direction of rotation of the aforesaid lift rod  1  is subject to the receiving or extending action of the blind. Therefore, when the user suddenly holding the bottom rail of the blind in position during up or down stroke of the bottom rail, the first or second pawl is forced into engagement with the corresponding ratchet to lock the lift rod  1 , and therefore the bottom rail is accurately positioned in position. In general, the invention eliminates the drawback of unstable positioning of the conventional designs due to excessive reversing power or elastic fatigue of the reversing spring.