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BACKGROUND OF THE INVENTION  
         [0001]    The present invention is generally related to window coverings and is more specifically related to cordless blinds for covering window openings.  
           [0002]    Window blinds are typically used for covering window openings. The blinds are usually moveable between an open position so that light may pass through the window and a lowered or closed position in which the window blind at least partially blocks the passage of light. A closed window blind also provides privacy so that individuals outside a building may not look into a building. Most window blinds include a lifting cord which passes through an aperture in each of the slats or through a window covering material such as cellular or pleated shades.  
           [0003]    There have been many improvements related to cordless window blinds. Such improvements attempt to simplify the process of operating a window blind and facilitate cleaning of the blind.  
           [0004]    For example, U.S. Pat. No. 1,798,869 discloses in FIG. 1 a headrail for a Venetian blind including a traversing rod  16  to which there is attached a pair of lift cords  20 ,  21 . U.S. Pat. No. 1,978,152 discloses a blind incorporating a traversing rod  1  from which there is supported a plurality of slats. Referring to FIG. 6 of the &#39;152 patent, the traversing rod may be operated by a hand crank assembly  23  that is coupled via rod  19  to an end of the traversing rod by means of a gear assembly (FIG. 3).  
           [0005]    U.S. Pat. No. 5,318,090 is directed to a roller assembly for a Venetian blind. Referring to FIG. 1 thereof, the roller assembly includes an elongated driving member  62  having a circular axial hole  623  extending through a rectangular shaft section  621 . The shaft section is received within the end portion of a rotating rod  50 . A guide unit  63  includes a threaded rod  633  extending through the circular axial hole of the driving member and into engagement with a moveable member  61  that is fixed in an intermediate position within the rotating rod. A lift cord is coupled to a portion of the driving member to rotate same in either a clockwise or counterclockwise direction. When the lift cord is pulled, the driving member rotates the rotating rod to move the moveable member along the threaded rod of the guide unit, thereby both rotating and moving the rotating rod along the guide unit.  
           [0006]    U.S. Pat. No. RE 35,926 is directed to a Venetian or pleated blind that is adapted to be positioned between a pair of glass panes. Referring to FIGS. 1 and 2 thereof, the blind includes a housing having two corner spacer elements  26 ,  32  attached to opposite ends of the headrail housing. Each of the corner spacer elements are attached to respective adjacent side spacer elements  60 ,  62  on each side of the window. The headrail defined by housing elements  4 ,  8  includes a traversing rod  16  referred to in the claims as a winding shaft.  
           [0007]    U.S. Pat. No. 5,482,100 is directed to a blind including at least one constant variable spring force motor having an elongated spring. The spring has a generally rectangular cross-section which varies in width from one end to the other. The varying spring force is sufficient to maintain the bottom rail in any position with respect to the top rail as the shade material accumulates on the bottom rail when moving the bottom rail towards the headrail.  
           [0008]    U.S. Pat. No. 5,531,257 is directed to a cordless blind having a spring motor coupled to an electronic motor. The electronic motor and the spring motor rotate a cord spool to raise or lower the window covering.  
           [0009]    U.S. Pat. No. 6,234,236 discloses a cordless window covering system incorporating a plurality of spring motors that are coupled together. Referring to the figures, the system includes at least two springs motors  40  in combination with a coupler  62 ,  62 A. The coupler connects the spring motors together to have a combined spring force. In other embodiments, the pair of spring motors are coupled together and attached to the lift cords.  
           [0010]    U.S. Pat. No. 6,079,471 teaches a window covering including a friction imparting member to inhibit movement of the bottom rail. Referring to FIG. 2 thereof, the friction and parting member includes a bracket  55  having a plurality of slots  56  that are used to increase the tension on cord  52  traveling through hole  50  in surface  47  towards the cord spool  30 .  
           [0011]    U.S. Pat. No. 6,129,131 is generally directed to a blind system including a traversing rod  32  coupled to a pull system  38  that imparts uni-directional movement to the coupling drive shaft  40 . The pull system includes a one-way clutch assembly  50  and a main drive assembly  42  including a single pull tape  46  operative of a drive spool  48 . The brake arm  150  is adapted to selectively prevent or permit lowering of the shade by gravity. The traversing assembly includes a compression spring  210  having one end slidably engaged with a disc-shaped end  220  of the cord spool  206 . The other end of the compression spring is attached to a spring support spool that is rotatable by the drive shaft. The compression spring is relatively light, but strong enough to push the cord spool to the left when no counterforces exist.  
           [0012]    Three related patents, U.S. Pat. No. 5,813,447; U.S. Pat. No. 5,960,846 and U.S. Pat. No. 6,047,759 all teach a window shade incorporating an internal spring tensioning mechanism. The spring tensioning mechanism is adapted for tensioning the spring upon rotation of the shade bar in one direction and releasing the spring tension upon opposite shade bar rotation, with the releasing of the spring force accomplished by a manual force rotating the shade bar in the tensioning direction.  
           [0013]    Despite the above improvement, there remains a need for improved cordless blind assemblies.  
         SUMMARY OF THE INVENTION  
         [0014]    In accordance with certain preferred embodiments of the present invention, a window blind assembly includes a headrail having a longitudinal axis, a bottom rail suspended below the headrail and a window covering material extending between the headrail and the bottom rail, the window covering material having an upper end attached to the headrail and a lower end attached to the bottom rail. The assembly also preferably includes a traversable tube disposed in the headrail, the traversable tube having first and second ends, and a threaded support rod secured to the headrail adjacent a first end of the tube, the threaded support rod being threadably coupled with the first end of the tube for providing traversing motion to the tube. A spring motor is desirably secured to the headrail adjacent a second end of the tube, the spring motor is engaged with the second end of the traversable tube for selectively rotating the tube, whereby the drive gears rotate about respective axes that are substantially parallel to the longitudinal axis of the headrail.  
           [0015]    In certain preferred embodiments, the spring motor drive gears are coupled together by a timing belt. In further embodiments, a drive shaft has a first end coupled with a pulley and a second end coupled with the traversable tube. A drive plug may be secured in an opening at the second end of the tube, the drive plug having a drive plug opening adapted to slidably receive the second end of the drive shaft. The drive plug opening desirably has a generally square shape, and the drive shaft has a longitudinal axis with a cross-section of the drive shaft perpendicular to the longitudinal axis having a generally square shape.  
           [0016]    The assembly may also include a tensioning member positioned on the threaded support rod between the first end of the traversable tube and a first end of the headrail, the tensioning member including a compression spring positioned between two collars so that as the traversable tube is rotated, the tube is displaced longitudinally to engage the tensioning member for compressing the compression spring between the two collars.  
           [0017]    In operation, the compressed tension member applies an axial load at the first end of the traversing tube for limiting free rotation of the traversing tube.  
           [0018]    The assembly may also include a lift cord having an upper end secured to the traversing tube and a bottom end secured to the bottom rail. The traversing tube preferably has a longitudinally extending groove and the upper end of the lift cord is captured in the longitudinally extending groove. The assembly preferably includes a C-shaped clip adapted to fit closely over an outer surface of the tube for securing the upper end of the lift cord in the longitudinally extending groove of the tube.  
           [0019]    The assembly may also include a cradle mounted in the headrail for supporting rotational and traversing movement of the tube. In certain preferred embodiments, the cradle has at least one opening and the lift cord passes through the at least one cradle opening. In certain preferred embodiments, the cradle may have a pair of opposing sidewalls and a bottom wall, a first opening in one of the sidewalls and a second opening in the bottom wall, whereby the lift cord extends in a first axial direction between the traversing tube and the first lateral sidewall opening, a second axial direction between the first cradle opening and the second cradle opening and a third axial direction between the second cradle opening and the bottom rail.  
           [0020]    A first headrail end cap may be secured over a first open end of the headrail, and a second headrail end cap may be secured over a second open end of the headrail. The first headrail end cap desirably has an inner surface defining a slot and the threaded support rod has a head adapted to fit into the slot for securing the threaded support rod to the first headrail end cap.  
           [0021]    In certain preferred embodiments, the spring motor includes a threaded anchor post, and a screw is threaded into the anchor post, the screw including a head, whereby the second headrail end cap has an inner surface including a slot and the head of the screw is fit into the slot for securing the spring motor to the second headrail end cap. The spring motor may also include feet adapted to engage the headrail for securing the spring motor to the headrail.  
           [0022]    The assembly may also include a second lift cord spaced from the first lift cord, the first and second lift cords extending through the window covering material in directions that are generally parallel to one another. The window covering material may be selected from the group consisting of cellular fabric, pleated fabric and slats.  
           [0023]    In operation, rotation of the tube causes the lift cord to wind on the tube in a non-overlapping spiral. The window blind assembly is desirably lowered to a closed position by pulling the bottom rail away from the headrail for unwinding the lift cord and rotating the tube as the lift cord unwinds which traverses the tube toward the tensioning member for causing compression of the tensioning member. The spring motor is coupled with the traversing tube and provides a constant tension. The window blind assembly is desirably raised to an open position by lifting the bottom rail toward the headrail for releasing tension from the spring motor, releasing compression of the tensioning member and winding the lift cord around the traversing tube in a non-overlapping spiral as the tube moves back toward the spring motor. As the blind is lowered, the weight of the fabric decreases and the axial force of the compression member increases so as to counteract the decrease in fabric weight.  
           [0024]    In certain preferred embodiments, a cradle cover may be secured over the cradle, the cradle cover being adapted to prevent bunching up or looping of the lift cord as the lift cord is rewound on the tube.  
           [0025]    In other preferred embodiments, the tensioning member includes a compression spring slidable along the threaded rod between the head of the threaded rod and the threaded plug secured to the first end of the tube, a large diameter collar between the head of the threaded rod and the compression spring, and a small diameter collar between the threaded plug and the compression spring.  
           [0026]    Other preferred embodiments of the present invention disclose a window blind assembly including a headrail having a longitudinal axis, a bottom rail suspended below the headrail, a window covering material extending between the headrail and the bottom rail, the window covering material having an upper end attached to the headrail and a lower end attached to the bottom rail, and a traversable tube mounted in the headrail, the tube having first and second ends and extending in a direction substantially parallel to the longitudinal axis of the headrail. The assembly also desirably includes a threaded support rod secured to the headrail adjacent the first end of the tube, the threaded support rod being threadably coupled with the first end of the tube for providing traversing motion to the tube along the longitudinal axis of the headrail, and a spring motor secured to the headrail adjacent the second end of the tube, the spring motor having drive gears in communication with the second end of the tube for selectively rotating the tube. The spring motor desirably includes a storage drum, an output drum and an elongated spring connected to the storage and output drums, whereby the storage and output drums rotate along respective axes that are substantially parallel to the longitudinal axis of the headrail.  
           [0027]    The assembly may also include a drive shaft having a first end coupled with the spring motor drive gears and a second end coupled with the second end of the traversing tube, whereby rotation of the tube causes rotation of the drive shaft which in turn rotates the spring motor drive gears.  
           [0028]    In certain preferred embodiments, the spring motor includes a first power plate having first and second circular openings and a second power plate having first and second openings, the first and second power plates having opposing posts for assembling the first and second power plates together so that the respective first openings of the assembled power plates are aligned with one another and the respective second openings of the assembled power plates are aligned with one another. The storage drum desirably has bearing surfaces on opposite ends thereof engagable with the first openings of the assembled power plates for supporting rotation of the storage drum, and wherein the output drum has bearing surfaces on opposite ends thereof engagable with the second openings of the assembled power plates for supporting rotation of the output drum.  
           [0029]    In certain preferred embodiments, the first power plate has an exterior surface including a stub shaft and the output drum includes one of the drive gears integrally formed therewith, the one of the drive gears passing through the second opening of the first power plate. The assembly may also include a pulley rotatably mounted over the stub shaft of the first power plate, a timing belt coupling the pulley and the one of the drive gears passing through the second opening of the first power plate, and a retainer ring mounted over an outer end of the one of the drive gears passing through the second opening of the first power plate for retaining the timing belt on the one of the drive gears passing through the second opening of the first power plate. The retainer ring desirably has a flat surface and an opposite curved surface, the curved surface of the retainer ring desirably facing the timing belt.  
           [0030]    In other preferred embodiments, the first end of the drive shaft is coupled with the pulley. The first end of the drive shaft may have a generally square shaped cross section and the pulley may have a generally square shaped opening adapted to receive the first end of the drive shaft.  
           [0031]    In other preferred embodiments, a window blind assembly includes a headrail having a longitudinal axis, a bottom rail suspended below the headrail and a window covering material extending between the headrail and the bottom rail, the window covering material having an upper end attached to the headrail and a lower end attached to the bottom rail. The assembly also desirably includes a traversable tube disposed in the headrail, the traversable tube having first and second ends, and a threaded support rod secured to the headrail adjacent a first end of the tube, the threaded support rod being threadably coupled with the first end of the tube for providing traversing motion to the tube along the longitudinal axis of the headrail. The assembly also preferably includes a spring motor secured to the headrail adjacent a second end of the tube, the spring motor having drive gears in communication with the second end of the traversable tube for selectively rotating the tube and a tensioning member positioned on the threaded support rod between the first end of the traversable tube and an end of the headrail, the tensioning member including a compression spring positioned between two collars, whereby as the traversable tube is rotated, the tube is displaced along the longitudinal axis of the headrail and away from the spring motor so that the tube engages the tensioning member for compressing the compression spring between the two collars. The compressed tensioning member desirably applies an axial load on the first end of the traversable tube for limiting free rotation of the traversable tube.  
           [0032]    In other preferred embodiments, the spring motor drive gears are coupled together using a timing belt, and the assembly further includes a drive shaft having a first end coupled with one of the spring motor drive gears and a second end coupled with the traversable tube. The spring motor may include a first power plate having first and second circular openings, and a second power plate having first and second openings, the first and second power plates having opposing posts for assembling the first and second power plates together so that the respective first openings of the assembled power plates are aligned with one another and the respective second openings of the assembled power plates are aligned with one another.  
           [0033]    In other preferred embodiments, a storage drum having bearing surfaces on opposite ends thereof is engagable with the first openings of the power plates for supporting rotation of the storage drum and an output drum having bearing surfaces on opposite ends thereof is engagable with the second openings of the power plates for supporting rotation of the output drum. The first power plate desirably has an exterior surface including a stub shaft and the output drum includes one of the drive gears integrally formed therewith, the one of the drive gears passing through the second opening of the first power plate.  
           [0034]    These and other preferred embodiments of the present invention will be described in more detail below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]    [0035]FIG. 1 shows an exploded view of a cordless blind assembly, in accordance with certain preferred embodiments of the present invention.  
         [0036]    [0036]FIGS. 2A-2C show a right hand headrail end cap for the assembly of FIG. 1.  
         [0037]    [0037]FIGS. 3A-3C show a left hand headrail end cap for the assembly of FIG. 1.  
         [0038]    [0038]FIG. 4 shows a perspective end view of a headrail for the assembly of FIG. 1.  
         [0039]    [0039]FIG. 5 shows a perspective end view of a bottom rail for the assembly of FIG. 1.  
         [0040]    [0040]FIG. 6 shows end caps for the bottom rail of FIG. 5.  
         [0041]    [0041]FIG. 7 shows a perspective view of a tensioning member for the assembly of FIG. 1, in accordance with certain preferred embodiments of the present invention.  
         [0042]    [0042]FIG. 8A shows a side view of the tensioning member of FIG. 7, in accordance with further preferred embodiments of the present invention.  
         [0043]    [0043]FIG. 8B shows a cross-sectional view of the tensioning member of FIG. 7 in a non-compressed position.  
         [0044]    [0044]FIG. 8C shows the tensioning member of FIG. 8B in a compressed position.  
         [0045]    [0045]FIGS. 9A-9C show a large diameter collar for the tensioning member of FIG. 7.  
         [0046]    [0046]FIGS. 10A-10B show a small diameter collar for the tensioning member of FIG. 7.  
         [0047]    [0047]FIG. 11 shows a compression spring for the tensioning member of FIG. 7.  
         [0048]    [0048]FIG. 12 shows a tensioning member for a cordless blind assembly, in accordance with further preferred embodiments of the present invention.  
         [0049]    [0049]FIGS. 13A and 13B show a right hand power plate for a spring motor for the cordless blind assembly shown in FIG. 1.  
         [0050]    [0050]FIGS. 14A and 14B show a left hand power plate for a spring motor for the cordless blind assembly shown in FIG. 1.  
         [0051]    [0051]FIGS. 15A and 15B show exploded views of a spring motor for the cordless blind assembly of FIG. 1.  
         [0052]    [0052]FIG. 16 shows a fragmentary view of the spring motor of FIG. 15A in an assembled configuration.  
         [0053]    [0053]FIGS. 17A-17C show a storage drum for the spring motor of FIG. 15A.  
         [0054]    [0054]FIGS. 18A-18E show an output drum for the spring motor of FIG. 15A.  
         [0055]    [0055]FIGS. 19A-19F show the spring motor of FIG. 15A after full assembly thereof.  
         [0056]    [0056]FIG. 20 shows a drive shaft connectable with the spring motor of FIG. 15A.  
         [0057]    [0057]FIGS. 21A-21C show the drive shaft of FIG. 20.  
         [0058]    [0058]FIG. 22 shows the drive shaft of FIGS. 21A-21C connected with the spring motor of FIG. 15A.  
         [0059]    [0059]FIGS. 23A-23E show a cradle for the cordless blind assembly of FIG. 1.  
         [0060]    [0060]FIGS. 24A-24D show a threaded support rod for the cordless blind assembly of FIG. 1.  
         [0061]    [0061]FIGS. 25A-25C show a clip for the cordless blind assembly of FIG. 1.  
         [0062]    [0062]FIGS. 26A-26B show a traversing tube for the cordless blind assembly of FIG. 1.  
         [0063]    [0063]FIGS. 27A-27B show a pulley for the spring motor of FIG. 15A.  
         [0064]    [0064]FIGS. 28A-28C show a retainer ring for the spring motor of FIG. 15A.  
         [0065]    [0065]FIG. 29 shows a perspective view of the tube of FIG. 26A coupled with the spring motor of FIG. 15A, in accordance with certain preferred embodiments of the present invention.  
         [0066]    [0066]FIG. 30 shows the cordless blind assembly of FIG. 1 after assembly thereof, headrail in accordance with certain preferred embodiments of the present invention.  
         [0067]    [0067]FIG. 31 shows another view of the assembly of FIG. 30.  
         [0068]    [0068]FIG. 32 shows another view of the assembly of FIG. 30.  
         [0069]    [0069]FIG. 33 shows another view of the assembly of FIG. 30.  
         [0070]    [0070]FIG. 34 shows the tensioning member of FIG. 7 between a traversing tube and a left hand headrail end cap, in accordance with certain preferred embodiments of the present invention.  
         [0071]    [0071]FIG. 35 shows a cradle cover for the cordless blind assembly of FIG. 1, in accordance with certain preferred embodiments of the present invention.  
         [0072]    [0072]FIG. 36 shows the cradle cover of FIG. 35 assembled with a cradle and overlying a traversing tube.  
         [0073]    [0073]FIG. 37 shows a cradle for supporting a traversing tube with a lift cord passed through a window in the cradle in a zigzag path, in accordance with certain preferred embodiments of the present invention.  
         [0074]    [0074]FIG. 38 shows an exploded view of a cordless blind assembly, in accordance with other preferred embodiments of the present invention.  
         [0075]    [0075]FIG. 39 shows an end view of a headrail for the assembly of FIG. 38.  
         [0076]    [0076]FIG. 40 shows an end view of a bottom rail for the assembly of FIG. 38.  
         [0077]    [0077]FIG. 41 shows a headrail end cap for the headrail of FIG. 39.  
         [0078]    [0078]FIG. 42 shows bottom rail end caps for the bottom rail of FIG. 40.  
         [0079]    [0079]FIG. 43 shows a tie off for a lift cord for the assembly of FIG. 38.  
         [0080]    [0080]FIG. 44 shows an exploded view of a cordless blind assembly, in accordance with further preferred embodiments of the present invention.  
         [0081]    [0081]FIG. 45 shows an end view of a headrail for the assembly of FIG. 44.  
         [0082]    [0082]FIG. 46 shows an end view of a bottom rail for the assembly of FIG. 44.  
         [0083]    [0083]FIG. 47 shows a headrail end cap for the headrail of FIG. 45.  
         [0084]    [0084]FIG. 48 shows a bottom rail end cap for the bottom rail of FIG. 46.  
         [0085]    [0085]FIG. 49 shows a tie off for a lift cord for the assembly of FIG. 44.  
     
    
     DETAILED DESCRIPTION  
       [0086]    [0086]FIG. 1 shows an exploded view of a cordless blind assembly, in accordance with certain preferred embodiments of the present invention. The assembly includes a headrail  102 , a left hand headrail end cap  104  and a right hand headrail end cap  106 . The left hand and right hand end caps  104 ,  106  cover the respective left and right ends of headrail  102 . The assembly also preferably includes a tensioning member  108  including a large diameter collar  110 , a compression spring  112  and a small diameter collar  114 .  
         [0087]    The cordless blind assembly  100  desirably includes a first cradle  116  and a second cradle  118  assembled with headrail  102 . The assembly  100  also includes a central cradle  120 . In certain preferred embodiments, however, the central cradle  120  is not required. The first and second cradles  116 ,  118  are adapted to support rotational and traversing movement of tube  122 . The cellular shade  100  also includes threaded rod  124  and threaded plug  126  insertable into an opening at a first end of tube  122 . Cordless blind assembly  100  also includes a first cradle cover  128  for assembly with first cradle  116  and a second cradle cover  130  for assembly with second cradle  118 . Although not limited by any particular theory of operation, it is believed that, if the blind is raised slightly off-center, the cradle covers  128 ,  130  prevent lift cord slack from developing on one side of tube  122  as opposed to the other side of tube  122 .  
         [0088]    The cordless blind assembly  100  also includes clips  132  attachable over the outer surface of tube  122  for holding ends of lift cord  134  in place.  
         [0089]    The assembly  100  also includes a drive plug  136  insertable into an opening at a second end of tube  122 , and a drive shaft having  138  having a first end  140  adapted to engage an opening in drive plug  136 . Drive shaft  138  has a second end.  142  engageable with a power assembly  144 , such as a spring motor. The drive shaft is adapted to translate rotational movement to the drive plug, however, the drive plug is able to slide along the drive shaft to facilitate traversing movement of tube  122 .  
         [0090]    The cordless blind assembly  100  also preferably includes a mounting bracket  146  and mounting screws  148  for mounting the headrail  102  over a window opening. The assembly  100  also preferably includes a dust cover  150  adapted to cover the upper side headrail  102 , as well as the traversing tube  120  and power assembly  144  disposed within headrail  102 . The assembly  100  also includes a slat  152  assembled with an underside of headrail  102 . The slat  152  engages an upper end of a window covering material  154 , such as cellular fabric for attaching the window covering material  154  with headrail  102 . The assembly  100  includes a second slat  156  inserted into the bottommost cell of window covering material  154 . The second slat  156  engages an upper face of bottom rail  158  for connecting bottom rail  158  with the window covering material  154 . The bottom rail  158  includes openings at both ends adapted to receive bottom rail end caps  160 . The lift cord  134  has a lower end that is passed through window covering material  154 , bottom rail  158  and washer  162  for tying off the bottom end of lift cord  134  and securing the bottom end against an underside of bottom rail  158 . The assembly also includes a handle  164  attached to bottom rail  158 .  
         [0091]    Referring to FIG. 1, the cordless blind assembly  100  also includes a screw  166  connectable with the power assembly  144 . The screw  166  includes a head shaped to engage a notch formed in right hand headrail end cap  106 , so as to reliably secure power assembly  144  to headrail  102  and right hand headrail end cap  106 .  
         [0092]    [0092]FIGS. 2A-2C show right hand headrail end cap  106  including outer face  168 , inner face  170  and projections  172  engageable with slots formed at an end of the headrail shown in FIG. 1. The inner face  170  of right hand headrail end cap  106  includes a notch  174  adapted to receive and secure a head of screw  166  (FIG. 1), which in turn secures the power assembly  144  to the headrail  102  (FIG. 1).  
         [0093]    [0093]FIG. 3A shows the left hand headrail end cap  104  of FIG. 1 including outer face  176 , inner face  178  and projections  180  extending from inner face  178 . The projections  180  are adapted to engage slots formed in a left hand side of the headrail  102  of FIG. 1. Referring to FIGS. 3B and 3C, the left hand headrail end cap  104  includes a notch  182  adapted to receive an end of threaded rod  124  (FIG. 1).  
         [0094]    [0094]FIG. 4 shows an end view of headrail  102  including an opening  184  having slots  186  formed therein adapted to receive the projections  172  of right hand headrail end cap  106 .  
         [0095]    [0095]FIG. 5 shows an end view of bottom rail  158  including slots  188  formed therein. Referring to FIG. 6, the assembly includes bottom rail end caps  160 . Each bottom rail end cap  160  has projections  190  adapted to be inserted into the slots  188  of bottom rail  158 .  
         [0096]    Referring to FIG. 7, a tensioning member  108  is inserted between a headrail end cap (not shown) and the end of tube  122  remote from power assembly  144  (FIG. 1). The tube  122  has an opening at an end thereof adapted to receive threaded plug  126 . The threaded plug includes a central threaded opening  190  (FIG. 8B) adapted to receive threaded rod  124  having a head  125 . The periphery of threaded plug  126  has projections  127  adapted to engage internal notch  109  of large diameter collar  110 . The tensioning member is assembled about the exterior of threaded rod  124 . Tensioning member  108  includes large diameter collar  110 , small diameter collar  114  and compression spring  112  assembled between collars  110 ,  114 . The compression spring  112  is wound about threaded rod  124 . Although not limited by any particular theory of operation, it is believed that the tensioning member will place more holding force on the tube  122  as the bottom rail and the cellular fabric  154  are lowered down over the window opening. As the cellular fabric  154  is pulled down, the tube  122  will rotate for unwinding the lift cords and traverse to the left.  
         [0097]    Referring to FIG. 7A, in certain preferred embodiments, the tensioning member  108  includes a large diameter collar  110 , a small diameter collar  114  and a compression spring  112  assembled therebetween. The large diameter collar  110  includes a central opening  192  extending therethrough for receiving threaded rod  124  of FIG. 7. The larger diameter tubular cover  110  also includes an outer notch  194  formed at an end thereof adapted to engage head  125  of threaded rod  124  and an inner notch  109 . The tensioning member  108  also includes the small diameter collar  114  having a central opening  196  adapted to receive threaded rod  124  (FIG. 7). The compression spring  112  is preferably a helically wound compression spring.  
         [0098]    [0098]FIG. 8B shows tensioning member in an uncompressed position. As tube  122  traverses to the left, the threaded plug  126  of tube  122  engages small diameter collar  114  for compression spring  112  between large diameter collar  110  and small diameter collar  114 . Although not shown in FIGS. 8B and 8C, the outer end of large diameter collar includes a notch  194  that engages head  125  of threaded rod  124  for preventing rotational movement of large diameter collar  110 . The increasing force provided by the compression spring  112  increases the axial force at the end of the tube  122  for resisting axial movement of tube  122 .  
         [0099]    Referring to FIGS. 9A-9C, large diameter collar  110  includes an opening  198  sized to receive the compression spring  112  (FIG. 8), an outer wall  200  defining the central opening  198  and a central hub  202 . The central hub  202  includes a central bore  204  adapted to receive threaded rod  124 , so that threaded rod  124  (FIG. 1) may pass therethrough. The large diameter collar  110  also includes an outer notch  194  and an inner notch  109 . During compression of the tensioning member, the outer notch  194  engages the end cap and the inner notch  109  engages the end of tube  122  for preventing rotation of the tensioning member.  
         [0100]    Referring to FIGS. 10A-10B, the small diameter collar  114  has an outer wall  206  defining a central opening  208  sized to enable the threaded rod  124  (FIG. 1) to pass therethrough. The small diameter collar  114  also includes a head  210  and a top face  212  adapted to engage the head  125  of threaded rod  124  (FIG. 7).  
         [0101]    Referring to FIG. 11, compression spring  112  includes helically wound coils  214 . The compression spring has an opening at the first end  216  thereof adapted to receive the outer wall  206  of small diameter collar  114 . The compression spring  112  also includes a second opening at the second end  218  adapted to receive the central hub  202  of large diameter collar  110 .  
         [0102]    [0102]FIG. 12 shows a tensioning member for a cordless blind assembly, in accordance with further preferred embodiments of the present invention. The tensioning member is located within tube  122 ′ having a first end  123 ′ with a threaded plug  126 ′ secured therein. The assembly includes a threaded rod  124 ′ having a first end, including a head  125 ′, and a second end threaded into the threaded opening of threaded plug  126 ′. A compression spring  112 ′ is inserted over the second end of the threaded rod  124 ′ between washer  127 ′ and retainer  129 ′. As the cordless blind assembly is pulled down, the lift cord  134 ′ is unwound from the tube and the tube  122 ′ traverses to the left. Leftward movement of the tube compresses compression spring  112 ′, which increases the axial force applied to the end of the tube.  
         [0103]    [0103]FIGS. 13A-13B and  14 A- 14 B show power plates for the power assembly  144  shown in FIG. 1. Referring to FIGS. 13A-13B, right hand power plate  220  includes a pair of large posts  222   a  and  222   b , four smaller posts  224   a - 224   d , a stub shaft  226 , a large diameter hole  228  and a small diameter hole  230 . The right hand power plate  220  also includes a stub shaft throughbore  232  for enabling a drive shaft to pass therethrough, as will be described in more detail below. The upper large post  222   a  preferably includes a female opening  234  and the second large post  222   b  includes a male end projection  236 . Each of the smaller posts  224   a - 224   d  desirably have male end projections  238   a - 238   d.    
         [0104]    Referring to FIGS. 14A-14B, the power assembly also includes a left hand power plate  240  having a pair of large posts  242   a  and  242   b . The first large post  242   a  includes a male projection  244  and the second large post  242   b  includes a female opening  246 . The large posts  222   a ,  222   b ,  242   a ,  242   b  of the respective right and left end power plates  220 ,  240  are adapted to snap-fit together. The left hand power plate  240  also includes smaller posts  248   a - 248   d  having female openings  250   a - 250   d . The left hand power plate  240  includes a large diameter opening  252  and a small diameter opening  254 .  
         [0105]    [0105]FIGS. 15A and 15B show an exploded view of the power assembly of FIG. 1, in accordance with certain preferred embodiments of the present invention. The power assembly includes right hand power plate  220  and left hand power plate  240 . The power assembly also includes storage drum  256  having opposing hubs  258   a ,  258   b  for rotating within small diameter openings  230  and  254  of the respective power plates. The assembly also includes an output drum  260  having an output drum gear  262  integrally molded thereto. The output drum includes bearing surfaces  264   a ,  264   b  that rotate within large diameter openings  228 ,  252  of the respective power plates. The power plate assembly  144  also includes a pulley  266  adapted to be fit over stub shaft  226 , a timing belt  268  that engages pulley  266  and output drum gear  262  and a retainer ring  270  having inwardly projecting teeth  272 . The exploded assembly shown in FIGS. 15A and 15B does not show a spring wrapped around storage drum and output drum  260 . In operation, the spring preferably travels under the storage drum  256  and over the output drum  260  in the direction indicated by the arrow designated  274  in FIGS. 15A and 15B. The spring preferably stores and releases tension from the power assembly.  
         [0106]    Referring to FIG. 15B, the right hand power plate  220  includes screw anchor post  276  having an internally threaded opening  278  with screw  280  secured in the threaded opening  278 . Timing belt  268  includes teeth  282  that mesh with teeth  284  on pulley  266  and teeth  286  on output drum gear  262 . Pulley  266  includes an annular opening  288  that is adapted to receive stub shaft  226  so that the pulley  266  is free to rotate about stub shaft  226 .  
         [0107]    Referring to FIG. 16, retainer  270  preferably includes a curved face  290  that faces timing belt  268  for holding the timing belt in place over output drum gear  262  (not shown).  
         [0108]    [0108]FIGS. 17A-17C show storage drum  256  having an outer surface  292 , a first retaining surface  294 , a second retaining surface  296 , a first bearing surface  258   a  and a second bearing surface  258   b.    
         [0109]    Referring to FIGS. 18A-18E, output drum  260  has an outer spring engaging surface  298 , a first retaining surface  300  and a second retaining surface  302 . The output drum  260  also includes first bearing surface  264   a  and second bearing surface  264   b . An output drum gear is integrally molded to output drum  260 . The output drum gear  262  includes teeth  286  and an hexagonal projection  304  projecting therefrom. The hexagonal projection  304  is adapted to engage the teeth  272  of retainer ring  270  (FIG. 15A). The output drum  260  includes one or more openings  306  extending through the outer wall  298  thereof for receiving and securing an end of a spring (not shown).  
         [0110]    [0110]FIGS. 19A-19F show the power assembly  144  after all the components described above have been assembled together. Referring to FIG. 19A, right hand power plate  220  and left hand power plate  240  are snap fit together by large posts  222   a  and  242   a . Pulley  266  is assembled over the stub shaft (not shown) and output drum gear  262  projects through the large diameter opening  252  of the left hand power plate  240 . The timing belt  268  has teeth  282  that mesh with the teeth  284  of pulley  266 , as well as the teeth (not shown) of the output drum gear  262 . Retainer ring  270  is secured over hexagonal projection  304  for holding the timing belt  268  in engagement with the teeth of the output drum gear  262 .  
         [0111]    [0111]FIG. 19B shows a right side perspective view of the assembly including screw  280  secured in threaded opening  278  of screw anchor post  276 . The large posts  222 B,  242 B of the opposing power plates  220 ,  240  are snap-fit together.  
         [0112]    [0112]FIG. 19D shows timing belt  268  having teeth  282  that mesh with the teeth  284  of pulley  266  and the teeth  286  of output drum gear  262 . FIG. 19E shows a top plan view of the power assembly  144  of the present invention including storage drum  256  and output drum  260 . Screw  280  is adapted for engaging an end cap of the headrail for holding the power assembly  144  securely in place. Retainer ring  270  holds timing belt  268  in proper engagement with output drum gear  262  and pulley  266 .  
         [0113]    [0113]FIG. 19F shows storage drum  256 , output drum  260  and spring  306  passing between storage drum  256  and output drum  260 . The spring  306  travels in the direction indicated by the arrow designated  274 . As noted above, the spring is utilized to store and release tension from the power assembly  144 .  
         [0114]    [0114]FIGS. 20 and 21A- 21 C show a drive shaft  138  having a first end  140  and a second end  142 , the first end being adapted to mesh with the square opening  267  of pulley  266 . Referring to FIG. 21A, drive shaft  138  has a square-shaped outer surface when viewed in cross-section. The square-shaped outer surface is best shown in FIG. 21C. Referring to FIG. 21B, drive shaft  128  includes stop ring  310 , snap barbs  312  and bifurcated end  314 . The bifurcated end  314  includes an upper arm  316  and a lower arm  318  that may be compressed toward one another. Referring to FIGS. 20 and 21B, during assembly the bifurcated end  314  is inserted into the square shaped opening  276  of pulley  266  and passes through the opening  232  of stub shaft  226 . As the bifurcated end  314  is passing through the stub shaft, the arms  316  and  318  are compressed together. After the bifurcated end  314  has been fully inserted through the stub shaft, the two arms  316 ,  318  are free to flex away from one another so that the retaining barbs  320 ,  322  engage the inside surface of right hand power plate  220  for holding the drive shaft secured to the power plate. The retaining barbs  320 ,  322  are angled away from the tip of the bifurcated end  314  for increasing grip as axial load increases. At this point, the drive shaft is free to rotate simultaneously with pulley  266 . The square outer surface of the drive shaft between the stop ring  310  and the barbs  312  has a square outer surface that closely engages the square or square-shaped opening  267  of pulley  266 . FIG. 22 shows the drive shaft  138  assembled with the power assembly  144 . As a result, any rotation of pulley  266  will drive the drive shaft  138 , and rotation of the drive shaft will rotate pulley  266   
         [0115]    [0115]FIGS. 23A-23E show a cradle  116  adapted to facilitate rotational and traversing movement of a tube  122  (FIG. 1). The cradle  116  includes a tube bearing surface  324 , a ladder drum bearing surface  326  and a securing element  328  adapted for securing cradle  116  to the headrail of the assembly. The cradle has a side window  330  passing through a side wall  332  thereof. The cradle also includes a ladder opening  334  adjacent a front end  336  of the cradle, a first opening  338  for a lift cord, a second opening  340  for a second lift cord and a second ladder opening  342  adjacent the rear end  344  of cradle  116 .  
         [0116]    [0116]FIGS. 24A-24D show a threaded rod  124  having a tip end  344  and head  125  remote from tip end  344 . The threaded rod  124  includes threads  348  extending between tip end  344  and head  125 . Head  125  includes a substantially V-shaped notch  350  formed therein. In other preferred embodiments, the V-shaped notch may have different geometric shapes.  
         [0117]    [0117]FIGS. 25A-25C show clip  132 , preferably made of a flexible material such as metal. The clip  132  is fastened over the outer surface of tube  122  (FIG. 26A) for holding an end of cord  134  securely fastened to the tube  122 .  
         [0118]    [0118]FIGS. 26A and 26B show tube  122  having an outer surface  346  with elongated grooves  348  formed therein. In certain preferred embodiments, the tube has one elongated groove. In other preferred embodiments, the tube has two, three or more elongated grooves.  
         [0119]    [0119]FIGS. 27A and 27B show pulley  266  having teeth  284  and a square shaped opening  267  formed at one end thereof. As noted above, the square shaped opening  267  is adapted to receive the square-shaped outer surface of the drive shaft so that the pulley  266  and drive shaft rotate simultaneously with one another. Referring to FIG. 27B, the opposite end of pulley  266  includes an annular opening  269  adapted to engage the outer surface of stub shaft  226  (FIG. 13A)  
         [0120]    [0120]FIGS. 28A-28C show retainer  270  including inwardly projecting teeth  272 . The retainer  270  has a curved surface  290 . In certain preferred embodiments, the retainer  270  includes a substantially convex surface  291  opposite the curved surface  290 .  
         [0121]    [0121]FIG. 29 shows the power assembly  144  of FIG. 15A coupled with tube  122  by drive shaft  138 . The tube  122  has an opening at a right end thereof and a drive plug  136  inserted in the opening. The tube is supported by a first cradle  116  and a second cradle  118 . The cradles include bearing surfaces that facilitate rotational and traversing movement of tube  122 . The left end of tube  122  is supported by end cap  104  having notch  182  formed therein for supporting a head of threaded rod  124 . The threaded rod  124  is secured in threaded plug  126  attached to the end of tube  122 .  
         [0122]    [0122]FIG. 30 shows another preferred embodiment of the present invention including power assembly  144  connected with tube  122  via drive shaft  138 . The drive shaft  138  has a first end connected with the power assembly  144  and a second end which engages drive plug  136  secured in an opening of tube  122 . An opposite end of tube  122  is secured to left hand headrail end cap  104  by head  125  of threaded rod  124  (not shown). The head  125  of threaded rod  124  is secured within a notch  182  formed in left hand headrail end cap  104 . A tensioning member  108  including a compression spring  112  is secured between the end of tube  122  and left hand headrail end cap  104 . A first cradle  116  and a second cradle  118  support rotational and traversing movement of tube  122 . A cradle cover  130  is coupled to first cradle  116 .  
         [0123]    [0123]FIG. 31 shows another perspective view of a cordless blind assembly  100  including headrail  102  supporting power assembly  144  and tube  122 . The power assembly  144  includes pulley  266  coupled with drive shaft  138 . As will be described in more detail below, during downward movement of the cellular shade, tube  122  rotates as the lift cords (not shown) are unwound from the tube  122 . In turn, rotation of tube  122  drives drive shaft  138 , which in turn rotates pulley  266 . Rotation of pulley  266  drives timing belt  268  which, in turn, rotates output drum gear  262 . Rotation of output drum gear  262  rotates output drum  260  which takes up the spring stored on storage drum  256 . Referring to FIGS. 30 and 31, as the cordless blind is pulled downward, the threaded rod  124  attached to the left hand rail end cap  104  causes tube  122  to move to the right. This causes the tension member, and particularly the spring  112  of the tension member  108 , to compress, which places axial holding forces on the remote end of tube  122 . The axial holding force tends to hold the tube stationary and in place.  
         [0124]    [0124]FIG. 32 shows yet another view of the assembly of the present invention including headrail  102  and left hand end cap  104  supporting rotation of tube  122 . The assembly includes a first cradle  116  and a second cradle  118 . The first and second cradles  116 ,  118  support rotational and traversing movement of tube  122 . The first end of tube  122  has secured therein a drive plug  136  with a preferably square opening  139  adapted to receive the square cross-sectional shaped drive rod (not shown). As noted above, left hand headrail end cap  104  includes a notch  182  for securing head  125  of threaded rod  124 .  
         [0125]    [0125]FIG. 33 shows the second end of tube  122  including threaded plug  126  having a central opening  127  with threads  129 . The threads  129  of the threaded plug  126  engage the external threads of threaded rod  124  (FIG. 32). As the tube rotates in the counterclockwise direction, the tube traverses to the right along the threaded rod for moving the second end of the tube  122  closer to the left-most end of headrail  102 .  
         [0126]    [0126]FIG. 34 shows an expanded view of tensioning member  108  including large diameter collar  110 , small diameter collar  114  and compression spring  112  disposed between the large diameter collar  110  and the small diameter collar  114 . Threaded road  124  has a head  125  secured in notch  182  of left hand headrail end cap  104 . The assembly includes threaded plug  126  secured in an opening at the end of tube  122  for engaging the external threads (not shown) of threaded rod  124 . The tensioning member  108  is secured between the threaded plug  126  and the left hand headrail end cap  104 . As the cellular shade is payed out, the tube  122  rotates in a direction indicated by arrow  400 . As the tube  122  rotates, the tube  122  moves to the right for abutting threaded plug  126  against small diameter collar  114 . Further rightward movement of tube  122  compresses the tensioning member  108  between the threaded plug  126  and the inner face of left hand headrail end cap  104 . Further paying out of the cellular shade results in further rightward movement of tube  122  for providing further axial force by the tensioning member  108 . As the cellular shade is lifted up toward the headrail  102 , the tube  122  rotates in an opposite direction from the direction indicated by arrow  400  and the tube moves leftward along the threaded rod  124 . This reduces the amount of compression upon the tensioning member  108 .  
         [0127]    [0127]FIG. 35 shows a cradle cover  130  which may be assembled over a cradle  116  that supports a rotating tube. The cradle cover  130  includes first and second opposing flanges  131 ,  133  that facilitate securing the cradle cover  130  to cradle  116 . Referring to FIG. 36, cradle cover  130  is secured over cradle  116  so that tube  122  is moveable between the cradle  116  and the cradle cover  130 . Opposing flanges  131  and  133  facilitate attachment of cradle cover  130  to cradle  116 . Specifically, a side wall  117  of cradle passes between opposing flanges  131  and  132  of cradle cover  130 . Although not limited by any particular theory of operation, it is believed that cradle cover  130  prevents slack from developing in a lift cord (not shown) as the lift cord is wound and unwound from tube  122 .  
         [0128]    [0128]FIG. 37 shows lift cord  134  wrapped around tube  122 . An end  135  of lift cord  134  is secured in an elongated groove  348  and held in the groove  348  by clip  132 . The clip preferably covers the groove  348  for holding the end  135  of cord  134  in place so that the cord  134  does not move. The cord is then directed through lateral window  330  of cradle  116  and opening  340  extending through a bottom wall  341  of cradle  116 . The lift cord  134  follows a zigzag path whereby the cord engages a periphery of window  330  and a periphery of opening  340 . The engagement of the cord with the edges of the openings  330 ,  340  creates friction that is believed to provide better holding force for the cordless blind assembly. This tends to hold the cellular shade in place as it is raised and lowered relative to the window opening.  
         [0129]    [0129]FIG. 38 shows a pleated shade assembly  1100  in accordance with certain preferred embodiments of the present invention. The pleated shade assembly  1100  is generally similar to the assembly shown in FIG. 1, however, the window covering material is a pleated fabric  1154 . Referring to FIGS. 39 and 40, the assembly  1100  includes a headrail  1102  and a bottom rail  1158 . Referring to FIG. 41, the assembly includes headrail end caps  1104  and  1106  that cover the respective left and right ends of headrail  1102  shown in FIG. 39. FIG. 42 shows bottom rail end caps  1160  for capping the respective left and right ends of bottom rail  1158  shown in FIG. 40. FIG. 43 shows a tie off  1162  for tieing off an end of cord  1134  that has passed through bottom rail  1158 .  
         [0130]    Referring to FIGS. 44-49, a shade assembly  2100  in accordance with another preferred embodiment of the present invention includes aluminum slats  2154 , headrail  2102 , and bottom rail  2158 . The ends of the headrail  2102  are covered by headrail end caps  2104  and  2106 . The openings at the ends of the bottom rail  2158  are covered by the bottom rail end caps  2160 . The lower end of lift cord  2134  is secured to bottom rail  2158  by tie-off  2164 . Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

Summary:
A window blind assembly includes a headrail having a longitudinal axis, a bottom rail suspended below the headrail and a window covering material extending between the headrail and the bottom rail, the window covering material having an upper end attached to the headrail and a lower end attached to the bottom rail. The assembly also includes a traversable tube disposed in the headrail, the traversable tube having first and second ends. The assembly includes a threaded support rod secured to the headrail adjacent a first end of the tube, the threaded support rod being threadably coupled with the first end of the tube for providing traversing motion to the tube. The assembly also includes a spring motor secured to said headrail adjacent a second end of the tube. The spring motor has drive gears in communication with the second end of the traversable tube for selectively rotating the tube, whereby the drive gears rotate about respective axes that are substantially parallel to the longitudinal axis of the headrail.