Abstract:
A rotator, which is driven by an endless cord member to rotate, is used in a window blind for driving a roller of the window blind. The rotator includes a base having a shaft, a first clamping plate and a second clamping plate rotatably serially mounted on the shaft of the base for clamping the cord member therebetween, and an elastic biasing device provided between the base and one of the first and second clamping plates for urging the first and second clamping plates against each other.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to generally to a rotator, which is connected with and driven by an endless cord member, for use in a window blind for driving a roller around which a blind shade is wound, and more particularly to such a cord-driven rotator, which has a cord member clamping function that prevents the cord member from slipping relative to the rotator.  
         [0003]     2. Description of the Related Art  
         [0004]     A conventional cord-driven rotator for use in a lifting window blind or the like is known comprising a base, which has a shaft, a friction wheel, which is pivoted to the shaft and has a V-shaped groove extended around the periphery, and an axle sleeve sleeved onto the shaft and connected between the friction wheel and the roller for synchronous rotation with the friction wheel on the shaft for driving the roller of the lifting window blind. The endless lift cord of the lifting window blind is hung in the V-shaped groove of the friction wheel and extended around the periphery of the upper half of the friction wheel. When pulling the lift cord, the friction wheel is driven by the lift cord to rotate the axle sleeve on the shaft, thereby causing the roller of the lifting window blind to rotate and to further lift or lower the blind shade that is connected to the roller. The V-shaped groove receives the lift cord, preventing slipping of the lift cord. In an alternative design of the conventional cord-driven rotator, the friction wheel is made having recessed round holes in two opposite sides thereof adjacent to the V-shaped groove for accommodating the beads of a lift cord formed of a chain of beads. However, because the pitch between each two adjacent recessed round holes is fixed, the friction wheel fits only one specific chain of beads. Therefore, different friction wheels shall be used to fit different sizes of chains of beads.  
         [0005]     Further, after a long time of use of the cord-driven rotator, the V-shaped groove or the recessed round holes may become wear, thereby not enabling to hold the lift cord in place.  
       SUMMARY OF THE INVENTION  
       [0006]     It is one objective of the present invention to provide a cord-driven rotator, which has a cord member clamping function that prevents the cord member from slipping relative to the rotator.  
         [0007]     It is another objective of the present invention to provide a cord-driven rotator, which fits any of a variety of cord members of different thickness.  
         [0008]     To achieve these objectives of the present invention, the cord-driven rotator, which is driven by an endless cord member to rotate and is used in a window blind for driving a roller of the window blind, comprises a base having a shaft, a first clamping plate and a second clamping plate rotatably serially mounted on the shaft of the base for clamping the cord member therebetween, and an elastic biasing device provided between the base and one of the first and second clamping plates for urging the first and second clamping plates against each other. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a perspective view of a cord-driven rotator according to a first preferred embodiment of the present invention.  
         [0010]      FIG. 2  is an exploded view of the cord-driven rotator according to the first preferred embodiment of the present invention.  
         [0011]      FIG. 3  is a front view of the cord-driven rotator according to the first preferred embodiment of the present invention.  
         [0012]      FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 3 .  
         [0013]      FIG. 5  is a perspective view of a cord-driven rotator according to a second preferred embodiment of the present invention.  
         [0014]      FIG. 6  is an exploded view of the cord-driven rotator according to the second preferred embodiment of the present invention.  
         [0015]      FIG. 7  is a sectional view taken along line  7 - 7  of  FIG. 6 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Referring to  FIGS. 1-4 , a cord-driven rotator  100  according to the first preferred embodiment of the present invention is shown comprised of a base  10 , a first clamping plate  20 , a second clamping plate  30 , two positioning members  40 , a hub  50 , and an elastic biasing device  60 .  
         [0017]     The base  10  comprises a shaft  11 , which has a screw hole  12  axially extended in the distal end.  
         [0018]     The first clamping plate  20  is shaped like a circular member having a stop face  21 , a clamping face  22  opposite to the top face  21 , a center axle hole  23  cut through the stop face  21  and the clamping face  22  at the center and coupled to the shaft  11  of the base  10  to let the stop face  21  be set in close contact with the inside wall of the base  10 , a coupling groove  221  formed in the clamping face  22 , and a plurality of fins  24  equiangularly spaced around the periphery. The fins  24  each have a radially extended groove  241  corresponding to the clamping face  22 , and two sloping edges  242  radially extended along two sides of the groove  241 . The height of the sloping edges  242  gradually reduces in direction from the inner side toward the outer side.  
         [0019]     The second clamping plate  30  is shaped like a circular member having a stop face  31 , a clamping face  32  opposite to the stop face  31 , a center axle hole  33  cut through the stop face  31  and the clamping face  32  at the center and coupled to the shaft  11  of the base  10  to let the clamping face  32  face be set in contact with the clamping face  22  of the first clamping plate  20 , an axle sleeve  34  perpendicularly extended from the stop face  31  around the border of the center axle hole  33  and sleeved onto the shaft  11  of the base  10 , the axle sleeve  34  having a slot  341  axially extended to the front and bottom ends thereof, a coupling block  321  perpendicularly extended from the clamping face  32  and coupled to the coupling groove  221  of the first clamping plate  20  to let the second clamping plate  30  be synchronous rotatable with the first clamping plate  20  on the shaft  11  of the base  10 , and a plurality of fins  35  equiangularly spaced around the periphery. The fins  35  each have a radially extended groove  351  corresponding to the clamping face  32 , and two sloping edges  352  radially extended along two sides of the groove  351 . The height of the sloping edges  352  gradually reduces in direction from the inner side toward the outer side. On design, the first clamping plate  20  and the second clamping plate  30  can be arranged to have the grooves  241  of the fins  24  of the first clamping plate  20  correspond to the grooves  351  of the fins  35  of the second clamping plate  30 . Alternatively, the first clamping plate  20  and the second clamping plate  30  can be so designed to have the grooves  241  of the fins  24  of the first clamping plate  20  and the grooves  351  of the fins  35  of the second clamping plate  30  be arranged in a staggered manner.  
         [0020]     The two positioning members  40  are two tensile springs mounted inside the axle sleeve  34  and adapted to stop the first clamping plate  20  and the second clamping plate  30  from rotation and to further stop the blind shade or slats of the window blind in position after release of an external driving force from the clamping plates  20 ,  30 . Since the structural relationship of the positioning member  40  are of known art, no more detailed description concerning the positioning members is recited.  
         [0021]     The hub  50  is a hollow member having a center through hole  521 , which diameter is greater than the outer diameter of the axle sleeve  34  of the second clamping plate  30 , a circular partition plate  51  radially extended around one end thereof, an inside annular flange  52  suspended in the center through hole  521 , an inside rib  54  axially extended from the inside annular flange  52  toward the circular partition plate  51 , and a plurality of radial flanges  53  equiangularly spaced around the periphery for engaging into the roller of a window blind (not shown). The hub  50  is sleeved onto the axle sleeve  34  of the second clamping plate  30  to engage the inside rib  54  into the slot  341  of the axle sleeve  34  of the second clamping plate  30  and to stop the circular partition plate  51  against the stop face  31  of the second clamping plate  30 . By means of the engagement between the inside rib  54  of the hub  50  and the slot  341  of the axle sleeve  34 , the hub  50  can be synchronously rotated with the second clamping plate  30  on the shaft  11  of the base  10 .  
         [0022]     The elastic biasing device  60  is comprised of a spring member  61 , a washer  62 , and a screw  63 . The spring member  61  has one side stopped at the inside annular flange  52  of the hub  50 . The washer  62  is stopped at the other side of the spring member  61 , having a center through hole  621 . The screw  63  is inserted through the center through hole  621  of the washer  62  and the spring member  61  and then threaded into the screw hole  12  of the shaft  11  of the base  10  to secure the washer  62  and the spring member  61  to the shaft  11 , thereby causing the spring member  61  to urge the hub  60  on the second clamping plate  30  and to further force the second clamping plate  30  against the first clamping plate  20 . Therefore, a clamping force is produced between the clamping face  22  of the first clamping plate  20  and the clamping face  32  of the second clamping plate  30  to retain the lift cord. Therefore, the invention effectively prevents slipping of the lift cord (insufficient friction force between the lift cord and the cord-driven rotator causes the lift cord to slip). When used with a lift chain of beads, the beads of the lift chain of beads be positioned in the between the matched grooves  241 ,  351  or in the grooves  241 ,  351  that are arranged in a staggered manner, preventing slipping of the lift chain of beads. In addition to the aforesaid cord member clamping effect, the pitch between the clamping face  22  of the first clamping plate  20  and the clamping face  32  of the second clamping plate  30  can be elastically adjusted to fit different thickness of lift cords or lift chains of beads.  
         [0023]      FIGS. 5-7  show a cord-driven rotator  200  constructed according to the second preferred embodiment of the present invention. The cord-driven rotator  200  is comprised of a base  10 , a first clamping plate  20 , a second clamping plate  30 , two positioning members  40 , and an elastic biasing device  60 .  
         [0024]     The base  10  comprises a shaft  11 , which has a screw hole  12  axially extended in the distal end.  
         [0025]     The first clamping plate  20  is shaped like a circular member having a stop face  21 , a clamping face  22  opposite to the top face  21 , a center axle hole  23  cut through the stop face  21  and the clamping face  22  at the center and coupled to the shaft  11  of the base  10  to let the stop face  21  be set in close contact with the inside wall of the base  10 , a coupling groove  221  formed in the clamping face  22 , and a plurality of fins  24  equiangularly spaced around the periphery. The fins  24  each have a radially extended groove  241  corresponding to the clamping face  22 , and two sloping edges  242  radially extended along two sides of the groove  241 . The height of the sloping edges  242  gradually reduces in direction from the inner side toward the outer side.  
         [0026]     The second clamping plate  30  is shaped like a circular member having a stop face  31 , a clamping face  32  opposite to the stop face  31 , a center axle hole  33  cut through the stop face  31  and the clamping face  32  at the center and coupled to the shaft  11  of the base  10  to let the clamping face  32  face be set in contact with the clamping face  22  of the first clamping plate  20 , a coupling block  321  perpendicularly extended from the clamping face  32  and coupled to the coupling groove  221  of the first clamping plate  20  to let the second clamping plate  30  be synchronous rotatable with the first clamping plate  20  on the shaft  11  of the base  10 , an axle sleeve  34  perpendicularly extended from the stop face  31  around the border of the center axle hole  33  and sleeved onto the shaft  11  of the base  10 , and a plurality of fins  35  equiangularly spaced around the periphery. The fins  35  each have a radially extended groove  351  corresponding to the clamping face  32 , and two sloping edges  352  radially extended along two sides of the groove  351 . The height of the sloping edges  352  gradually reduces in direction from the inner side toward the outer side. The axle sleeve  34  has radial flanges  36  equiangularly spaced around the periphery for engaging into the roller of a window blind (not shown).  
         [0027]     The two positioning members  40  are two tensile springs mounted inside the axle sleeve  34  and adapted to stop the first clamping plate  20  and the second clamping plate  30  from rotation and to further stop the blind shade or slats of the window blind in position after release of an external driving force from the clamping plates  20 ,  30 .  
         [0028]     The elastic biasing device  60  is comprised of a spring member  61 , a washer  62 , and a screw  63 . The spring member  61  is sleeved onto the shaft  11  of the base  10 , having one side stopped at the inside wall of the base  10  and the other side stopped at the stop face  21  of the first clamping plate  20 . The washer  62  is stopped at the remote end of the axle sleeve  34  of the second clamping plate  30 , having a center through hole  621 . The screw  63  is inserted through the center through hole  621  of the washer  62  and threaded into the screw hole  12  of the shaft  11  of the base  10  to secure the washer  62  to the shaft  11 . Therefore, the spring member  61  imparts a resilient contacting force to the first clamping plate  20  against the second clamping plate  30 , and a clamping force is produced between the clamping face  22  of the first clamping plate  20  and the clamping face  32  of the second clamping plate  30  to retain the lift cord that is positioned in between the clamping face  22  of the first clamping plate  20  and the clamping face  32  of the second clamping plate  30 . Therefore, the invention effectively prevents slipping of the lift cord. This embodiment can also be used with a lift chain of beads. When used with a lift chain of beads, the beads of the lift chain of beads can be positioned in the between the matched grooves  241 ,  351  or in the grooves  241 ,  351  that are arranged in a staggered manner, preventing slipping of the lift chain of beads. In addition to the aforesaid cord member clamping effect, the pitch between the clamping face  22  of the first clamping plate  20  and the clamping face  32  of the second clamping plate  30  can be elastically adjusted to fit different thickness of lift cords or lift chains of beads.  
         [0029]     In the aforesaid two embodiments, an elastic biasing device is used to urge two separated clamping plates toward each other. In the aforesaid first embodiment, the elastic biasing device indirectly forces the second clamping plate against the first clamping plate. In the aforesaid second embodiment, the elastic biasing device directly forces the first clamping plate against the second clamping plate.  
         [0030]     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.