Abstract:
A covering for an architectural opening has a horizontal movable rail supported by cords, with a variety of configurations which allow the movable rail to be moved up and down while concealing the cords.

Description:
[0001]    This application claims priority from U.S. Provisional Application Ser. No. 61/449,877, filed Mar. 7, 2011, which is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an arrangement for opening and closing coverings for architectural openings such as Venetian blinds, pleated shades, cellular shades, and vertical blinds. 
         [0003]    Usually, a transport system for a covering that extends and retracts in the vertical direction has a fixed head rail which both supports the covering and hides the mechanisms used to raise and lower or extend and retract the covering. Such a transport system is described in U.S. Pat. No. 6,536,503, Modular Transport System for Coverings for Architectural Openings, which is hereby incorporated herein by reference. In the typical covering product that retracts at the top and then extends by moving downwardly from the top (top/down), the extension and retraction of the covering is done by lift cords suspended from the head rail and attached to the bottom rail. In a Venetian blind, there also are ladder tapes that support the slats, and the lift cords usually run through holes in the middle of the slats. In these types of coverings, the force required to raise the covering is at a minimum when the covering is fully lowered (fully extended), since the weight of the slats is supported by the ladder tapes, so that only the bottom rail is being raised by the lift cords at the outset. As the covering is raised further, the slats stack up onto the bottom rail, transferring the weight of the covering from the ladder tapes to the lift cords, so progressively greater lifting force is required to raise the covering as it approaches the fully raised (fully retracted) position. 
         [0004]    Some window covering products are built to operate in the reverse (bottom-up), where the moving rail, instead of being at the bottom of the window covering bundle, is at the top of the window covering bundle, between the bundle and the head rail, such that the bundle is normally accumulated at the bottom of the window when the covering is retracted and the moving rail is at the top of the window covering, next to the head rail, when the covering is extended. There are also composite products which are able to do both, to go top-down and/or bottom-up. In the top-down/bottom-up (TDBU) arrangements, the window shades or blinds have an intermediate movable rail and a bottom movable rail. 
         [0005]    Known cord drives have some drawbacks. For instance, the cords in a cord drive may be hard to reach when the cord is high up (and the blind is in the fully lowered position), or the cord may drag on the floor when the blind is in the fully raised position. The cord drive also may be difficult to use, requiring a large amount of force to be applied by the operator, or requiring complicated changes in direction in order to perform various functions such as locking or unlocking the drive cord. There also may be problems with overwrapping of the cord onto the drive spool, and many of the mechanisms for solving the problem of overwrapping require the cord to be placed onto the drive spool at a single location, which prevents the drive spool from being able to be tapered to provide a mechanical advantage. 
         [0006]    It often is desirable to hide the cords so there are no loose cords. However, this can be difficult, especially when there is more than one movable rail, which generally means that there are many cords that have to be hidden. 
       SUMMARY 
       [0007]    Various arrangements are presented for moving a covering from one position to another using lift cords that are hidden and eliminating loose cords. In one embodiment, the user actuates a mechanism on a handle on a movable rail, and then raises or lowers the movable rail to extend or retract the covering. Release of the handle mechanism automatically locks the movable rail in the position it was in when the handle mechanism was released. 
         [0008]    In another embodiment, an indexing mechanism, functionally connected to the lift rod of the movable rail, functions to rotate lift stations in the movable rail that wind up or unwind the lift cord to raise or lower the movable rail. 
         [0009]    In another embodiment, an upper movable rail rides up and down on the lift cords of a lower movable rail. 
         [0010]    In still another embodiment, an upper movable rail is suspended on a first set of lift cords that extend upwardly to fixed points, and a lower movable rail is suspended from the upper movable rail by a second set of lift cords. This embodiment includes an arrangement that prevents the lower movable rail from extending beyond the bottom of the architectural opening when the upper movable rail is fully extended. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a cellular shade incorporating a lock mechanism shown in the locked position; 
           [0012]      FIG. 2  is a perspective view of the shade of  FIG. 1 , with the lock in the unlocked position; 
           [0013]      FIG. 3  is a partially exploded perspective view of the shade of  FIG. 1 , showing the components that are housed in the movable rail; 
           [0014]      FIG. 4  is a plan view of the lock mechanism of  FIG. 1 , with the top cover omitted for clarity, and showing the lift rod; 
           [0015]      FIG. 5  is the same view as  FIG. 4 , but with the lock mechanism in the unlocked position; 
           [0016]      FIG. 6  is an exploded perspective view of the lock mechanism of  FIG. 1 ; 
           [0017]      FIG. 7  is a rear perspective view of the slide element of the lock mechanism of  FIG. 6 ; 
           [0018]      FIG. 8  is a front view the lock mechanism of  FIG. 1 ; 
           [0019]      FIG. 9  is a section view along line  9 - 9  of  FIG. 8 ; 
           [0020]      FIG. 10  is a perspective view of the cellular shade of  FIG. 1 , but adding a pivot support attachment to aid in unlocking the shade if the lock mechanism is not readily accessible to the user; 
           [0021]      FIG. 11  is a perspective view, similar to  FIG. 10 , showing a lock release wand engaging the pivot support attachment for aiding in unlocking the shade; 
           [0022]      FIG. 12A  is a broken-away, section view along line  12 A- 12 A of  FIG. 11 ; 
           [0023]      FIG. 12B  is the same view as  FIG. 12A , but with the lock mechanism in the unlocked position; 
           [0024]      FIG. 13  is a perspective view of the pivot support attachment of  FIG. 11 ; 
           [0025]      FIG. 14  is a perspective view of the tip of the lock release wand of  FIGS. 10 and 11 ; 
           [0026]      FIG. 15  is a perspective view of the tip of the lock release wand of  FIG. 14 , as seen from a different angle. 
           [0027]      FIG. 16  is a perspective view of a top-down bottom-up cellular shade; 
           [0028]      FIG. 17  is an exploded perspective view of the head rail of the cellular shade of  FIG. 16 ; 
           [0029]      FIG. 18  is a perspective view of a top-down bottom-up cellular shade with a movable rail including a lock; 
           [0030]      FIG. 19  is a partially broken away, perspective view of the cellular shade of  FIG. 18 , with the rails omitted for clarity; 
           [0031]      FIG. 20  is an exploded perspective view of the cellular shade of  FIG. 18 , with the lift cords omitted for clarity; 
           [0032]      FIG. 21  is a bottom-end perspective view of one of the windlass assemblies of  FIG. 20 ; 
           [0033]      FIG. 22  is a top-end perspective view of the windlass assembly of  FIG. 21 ; 
           [0034]      FIG. 23  is an exploded perspective view of the windlass assembly of  FIG. 22 ; 
           [0035]      FIG. 24  is section view along line  24 - 24  of  FIG. 22 ; 
           [0036]      FIG. 25  is a perspective view of the windlass of  FIG. 24 ; 
           [0037]      FIG. 26  is section view along line  26 - 26  of  FIG. 22 ; 
           [0038]      FIG. 27  is a perspective view of an alternate windlass assembly which may be used in the cellular shade of  FIG. 20 ; 
           [0039]      FIG. 28  is an exploded perspective view of the windlass assembly of  FIG. 27 ; 
           [0040]      FIG. 29  is a plan view showing the housing of the windlass assembly of  FIG. 28 ; 
           [0041]      FIG. 30  is a plan view showing the housing cover of the windlass assembly of  FIG. 28 ; 
           [0042]      FIG. 31  is a section view along line  31 - 31  of  FIG. 27 ; 
           [0043]      FIG. 32  is a front perspective view of a cellular shade, similar to that of  FIG. 1 , but with a different drive mechanism; 
           [0044]      FIG. 33  is a rear perspective view of the cellular shade of  FIG. 32 ; 
           [0045]      FIG. 34  is a partially exploded perspective view of the cellular shade of  FIG. 32 ; 
           [0046]      FIG. 35  is a section view along line  35 - 35  of  FIG. 34 , but with the sprocket mounted onto the end cap; 
           [0047]      FIG. 36  is a section view along line  36 - 36  of  FIG. 35 ; 
           [0048]      FIG. 37  is a perspective view of the end cap of  FIG. 34 ; 
           [0049]      FIG. 38  is a perspective view of the sprocket of  FIG. 34 ; 
           [0050]      FIG. 39  is a perspective view of a cellular shade, similar to that of  FIG. 32 , but with index drive mechanisms at both ends of the shade; 
           [0051]      FIG. 40  is a schematic of a top down/bottom up shade with an automatic variable stroke limiter, with both movable rails in their retracted positions; 
           [0052]      FIG. 41  is a schematic of the shade of  FIG. 40  with the upper movable rail in its fully extended position and the lower movable rail in its fully retracted position; 
           [0053]      FIG. 42  is a schematic of the shade of  FIG. 40  with the upper movable rail in a partially extended position and the lower movable rail in a partially extended position; 
           [0054]      FIG. 43  is a schematic of the shade of  FIG. 40  with the upper movable rail in a partially extended position and the lower movable rail in its fully retracted position; and 
           [0055]      FIG. 44  is a schematic of the shade of  FIG. 40  but showing a covering extending from the upper movable rail to the lower movable rail and including brakes on both movable rails. 
       
    
    
     DESCRIPTION 
       [0056]      FIGS. 1 through 10  illustrate one embodiment of a horizontal covering for an architectural opening (which may hereinafter be referred to as a window covering or blind or shade). This particular embodiment is a cellular shade  10 , with a lock mechanism  12  (illustrated in further detail in  FIGS. 4 through 9 ). The user applies an outside force to de-activate the lock mechanism  12  for raising or lowering the shade (retracting and extending the expandable material). When the shade is in the desired position, the user stops applying the outside force, and the lock mechanism automatically locks and holds the shade in place. This same lift arrangement could be used for a Venetian blind. 
         [0057]    The shade  10  of  FIGS. 1-3  includes a head rail  14 , a bottom rail  16 , and a cellular shade structure  18  suspended from the head rail  14  and attached to both the head rail  14  and the bottom rail  16 . Lift cords (not shown) are attached to the head rail  14 , extend through openings in the cellular shade  18 , and terminate at lift stations  20  housed in the bottom rail  16 . A lift rod  22  extends through the lift stations  20  and through the locking mechanism  12 . The lift spools on the lift stations  20  rotate with the lift rod  22 , and the lift cords wrap onto or unwrap from the lift stations  20  to raise or lower the bottom rail  16  and thus raise or lower the shade  10 . A spring motor  24  is functionally attached to the lift rod  22  to provide an assisting force when raising the shade. 
         [0058]    These lift stations  20  and spring motor  24 , and their operating principles are disclosed in U.S. Pat. No. 6,536,503 “Modular Transport System for Coverings for Architectural Openings”, issued Mar. 25, 2003, which is hereby incorporated herein by reference. Very briefly, the lift rod  22  is rotationally connected to an output spool on the spring motor  24 . A flat spring (not shown) in the spring motor  24  has a first end connected to the output spool (having a first axis of rotation) of the spring motor  24 . The second end of the flat spring in the spring motor  24  is either connected to a storage spool (not shown) having a second axis of rotation, or is coiled about an imaginary axis defining this second axis of rotation. The flat spring is biased to return to its “normal” state, wound around the second axis of rotation, and typically this corresponds to when the shade  10  is in the fully raised position (retracted). As the shade  10  is pulled down (extended) the flat spring unwinds from the second axis of rotation and winds onto the output spool, increasing the potential energy stored in the spring. When the shade  10  is raised (retracted) the spring winds back onto the storage spool, using some of the potential energy to assist the user in raising the shade  10  by rotating the output spool and thus the lift rod  22  connected to the output spool of the spring motor  24 . 
         [0059]    In this embodiment, the main purpose of the spring motor is to wind up the lift cord as the shade  10  is raised. To operate the shade, the user applies an external force to unlock the locking mechanism  12  and manually positions the rail  16 . He then releases the external force, and the locking mechanism  12  automatically locks to hold the rail  16  in the desired position regardless of the relationship of the spring power to the weight of the shade. The spring may be underpowered (having enough power to wind up the lift cord but not enough power to raise the shade) or it may be overpowered (having enough power to wind up the lift cord and additional power to raise the shade). 
         [0060]    In one embodiment for a Venetian-type blind, this spring motor  24  includes a spring with a negative power curve such that, when the force required to raise the blind is at a minimum (when the Venetian blind is fully extended), the spring provides the least assist, and as a progressively greater lifting force is required to raise the slats of the blind (as the Venetian blind approaches the fully retracted position) the spring provides more of an assist. This spring with a negative power curve is disclosed in U.S. Pat. No. 7,740,045 “Spring Motor and Drag Brake for Drive for Coverings for Architectural Openings”, issued Jun. 22, 2010, which is hereby incorporated herein by reference. 
         [0061]    Each lift station  20  includes a lift spool which rotates with the lift rod  22 . The lift stations  20 , lift rod  22 , and spring motor  24  are mounted in the bottom rail  16 . When the lift rod  22  rotates, so do the lift spools of the lift stations  20 , and vice versa. One end of each lift cord is connected to a respective lift spool of a respective lift station  20 , and the other end of each lift cord is connected to the top rail  14 , such that, when the lift spools rotate in one direction, the lift cords wrap onto the lift spools and the shade  10  is raised (retracted), and when the lift spools rotate in the opposite direction, the lift cords unwrap from the lift spools and the shade  10  is lowered (extended). 
       Lock Mechanism 
       [0062]      FIGS. 4-9  show the details of the lock mechanism  12  of  FIG. 3 . Referring to  FIG. 6 , the lock mechanism  12  includes a housing  26 , a slide element  28 , a coil spring  30 , a splined sleeve  32 , and a housing cover  34 . 
         [0063]    The housing  26  is a substantially rectangular box having a flat back wall  36 , a flat front wall  38  which defines an opening  40 , and a forwardly extending fixed tab  42  secured to the front wall  38 . The side walls  44 ,  46  define aligned, U-shaped openings  48 ,  50  which rotationally support the splined sleeve  32 . The left side wall  44  also defines an inwardly extending projection  52  sized to receive and engage one end  54  of the coil spring  30 . The other end  56  of the coil spring  30  is received in a similar projection  58  on the slide element  28  (See  FIG. 7 ), as will be described in more detail later. 
         [0064]    The bottom wall  60  defines a ridge  62  which extends parallel to the front and rear walls  38 ,  36 . The bottom edge  64  of the slide element  28  is received in the space between the ridge  62  and the front wall  38 , so the ridge  62  and front wall  38  form a track that guides the slide element  28  for lateral, sliding displacement parallel to the flat front wall  38  of the housing  26 . A recessed shoulder  66  along the front of the housing cover  34  also extends parallel to the front wall  38 . The top edge  68  of the slide element  28  is received between the front wall  38  and the shoulder  66  to provide a similar linear, lateral guiding function for the top edge  68  of the slide element  28 , as described in more detail later. 
         [0065]    Referring to  FIG. 7 , the slide element  28  is a substantially T-shaped member with the leg of the “T” being a slide tab  70  which is substantially identical to the fixed tab  42  of the housing  26 , except that there is a through opening  27  through the slide tab  70 , the purpose of which is described later. As best appreciated in  FIGS. 4 and 5 , the fixed tab  42  and the slide tab  70  are substantially parallel to each other when the lock mechanism  12  is assembled, and the slide element  28  slides to the left (as seen from the vantage point of  FIGS. 4 and 5 ) toward the fixed tab  42  to unlock the lock mechanism  12 , as described in more detail later. 
         [0066]    Again referring to  FIG. 7 , the slide element  28  defines a wing projection  71  substantially opposite the spring-receiving projection  58 . As described in more detail later, this wing projection  71  slides between the splines of the splined sleeve  32  to prevent the splined sleeve  32  from rotating. 
         [0067]    The splined sleeve  32  (See  FIGS. 6 and 9 ) is a hollow, generally cylindrical body with an internal bore  72  having a non-circular profile. In this particular embodiment, it has a “V” projection profile. The lift rod  22  has a complementary “V” notch  22 A. The lift rod  22  is sized to nearly match the internal profile of the bore  72 , with the “V” projection of the bore  72  being received in the “V” notch  22 A of the lift rod  22 , such that the splined sleeve  32  and the lift rod  22  are positively engaged to rotate together. Thus, when the splined sleeve  32  is prevented from rotation, the lift rod  22  is likewise prevented from rotation. 
         [0068]    The splined sleeve  32  also defines a plurality of splines  74  extending radially at the right end portion of the splined sleeve  32  (as seen from the vantage point of  FIG. 6 ). The left end portion  76  of the splined sleeve  32  is a smooth, spline-less, cylindrical surface having the same outside diameter as the base from which the splines  74  project. 
       Assembly: 
       [0069]    Referring to  FIGS. 4-6 , to assemble the lock mechanism  12 , the first end  54  of the coil spring  30  is placed over the projection  52  on the housing  26 . The slide element  28  is then assembled such that the slide tab  70  projects through the opening  40  in the front wall  38  of the housing  26 , with the bottom edge  64  of the slide element  28  fitting in the space between the ridge  62  and the front wall  38  of the housing  26 . The second end  56  of the coil spring  30  receives the projection  58  (See  FIG. 7 ) of the slide element  28 , so the coil spring  30  is trapped between and is held in position by the two projections  52 ,  58 . 
         [0070]    The coil spring  30  acts as a biasing means which urges the slide element  28  to the right (as seen from the vantage point of  FIG. 4 ). To install the splined sleeve  32 , the user pushes the slide element  28  to the left, to the position shown in  FIG. 5 , such that the wing projection  71  clears the splines  74  of the splined sleeve  32 . The splined sleeve  32  is then dropped into place so that its ends rest on the curved bottoms of the openings  48 ,  50  in the side walls  44 ,  46 , which support the splined sleeve  32  for rotation. (Shoulders  73  near the ends of the splined sleeve  32  lie inside the housing  26  adjacent to the side walls  44 ,  46  and ensure that the splined sleeve  32  remains in the proper axial position relative to the housing  26 .) Finally, the housing cover  34  snaps on top of the assembly to keep the components together, with top edge  68  of the slide element  28  being received between the shoulder  66  of the housing cover  34  and the front wall  38  of the housing  26 , and the lift rod  22  is slid through the bore  72  of the splined sleeve  32  and through the lift stations  20  and into the spring motor  24 , as shown in  FIG. 3 . 
         [0071]    The assembled lock mechanism  12 , lift rod  22 , lift stations  20 , and spring motor  24 , are then mounted in the movable rail  16 . In this embodiment, the movable rail  16  is the bottom rail  16 , but it alternatively could be an intermediate rail, located between the head rail and a bottom rail (not shown). As another alternative, the entire mechanism, including the spring motor  24 , lift rod  22 , lift stations  20  and lock  12  could be located in the fixed head rail  14 , with the lift cords secured to the movable bottom rail, extending through the shade  18 , and winding up on the spools of the lift stations  20  in the fixed head rail. 
       Operation: 
       [0072]    Referring to  FIGS. 1 ,  2 ,  4 , and  5 , to raise or lower the shade  10 , the user pinches together the tabs  42 ,  70  of the lock mechanism  12 , which pushes the slide element  28  to the left (as seen in  FIG. 5 ), against the biasing force of the coil spring  30 . The wing projection  71  on the slide element  28  also moves to the left until it clears the splines  74  of the splined sleeve  32 , which frees the splined sleeve  32  and allows it to rotate. The lift rod  22 , which is functionally and positively connected to the splined sleeve  32 , now is also free to rotate. When the user is raising the shade  10 , the spring motor  24  assists the user by supplying some of the force required to rotate the lift rod  22  and with it the lift spools of the lift stations  20  to wind any lift cords onto these lift spools. 
         [0073]    The spring on the spring motor  24  may be overpowered (more powerful than required to overcome the force of gravity acting on the shade  10  so that it raises the shade  10 ), or it may be underpowered, so that the user has to provide some of the lifting force to raise the shade  10 . As discussed earlier, the spring in the spring motor  24  may include a spring with a negative power curve such that, when the force required to raise the blind is at a minimum (when the blind is fully extended), the spring motor  24  provides the least assist, and as a progressively greater lifting force is required to raise the blind (as the blind approaches the fully retracted position) the spring motor  24  provides more of an assist. 
         [0074]    When the user releases the tabs  42 ,  70  of the lock mechanism  12 , the coil spring  30  automatically pushes the slide element  28  to the right, as shown in  FIG. 4 , which slides the wing projection  71  to the right, so that it enters between two of the splines  74 , as shown in  FIG. 9 . This prevents the splined sleeve  32  from rotating further. Since the lift rod  22  is directly connected to the splined sleeve  32 , this also prevents the lift rod  22  and the lift stations, which are functionally connected to the lift rod  22 , from rotating, so the lift cords cannot unwind from their lift stations  20 , and the shade  10  remains in the position where it was released by the user. 
         [0075]      FIGS. 10-15  depict the shade  10  with an enhancement that may be added to make the lock  12  more readily accessible, especially when it might otherwise be too high up to reach. 
         [0076]    Referring to  FIGS. 10 and 11 , the enhancement includes a pivot support attachment  78  and a lock release wand  80 . Referring to  FIG. 13 , the pivot support attachment  78  has a substantially flat horizontal surface  82 , defining a circular through opening  84 , and two downwardly projecting ears  86 ,  88  defining countersunk openings  90 ,  92 , for receiving screws to secure the attachment  78  to the movable rail  16 . As seen in  FIGS. 10 and 11 , the pivot support attachment  78  is attached to the front, outside surface of the bottom rail  16  via screws  94 . 
         [0077]      FIGS. 14 and 15  show the engagement tip  96 , which is secured to the top of the lock release wand  80  (See  FIG. 11 ). This engagement tip  96  defines a first frustoconical surface  98  coaxial with the longitudinal axis of the lock release wand  80 , and a second frustoconical surface  100  mounted on an arm  102  which projects radially from the engagement tip  96 . The second frustoconical surface  100  is oriented perpendicular to the arm  102 . The bottom of the engagement tip  96  defines an opening  104  which receives the end of the lock release wand  80 , as seen in  FIG. 10 . 
         [0078]    If it is desirable to have means for extending the reach of the user to raise or lower the shade  10 , the pivot support attachment  78  is attached (using screws  94 , for instance) to the outer surface of the bottom rail  16  such that the two ears  86 ,  88  straddle the lock  12  and the ear  86  abuts the fixed tab  42  of the lock  12 . The lock release wand  80  is then inserted into the pivot support attachment  78  such that the first frustoconical surface  98  goes into the opening  84 , as shown in  FIGS. 10 and 11 . This first action properly locates the lock release wand  80  relative to the pivot support attachment  78  in preparation for controlling the lock  12 . 
         [0079]    Once the lock release wand  80  is in position, as shown in  FIG. 11 , it is rotated in a counter-clockwise direction about its longitudinal axis, as depicted by the arrow  106  in  FIG. 10 , until the second frustoconical surface  100  projects into the opening  27  (See  FIG. 12A ) in the slide tab  28  of the lock  12 , and the arm  102  is pressing against the slide tab  28 . Further rotation in the same counter-clockwise direction results in the arm  102  pushing the slide tab  28  toward the fixed tab  42 , which unlocks the lock  12  (See  FIG. 12B ). The shade  10  may now be raised or lowered by raising or lowering the lock release wand  80 . The second frustoconical surface  100  projecting through the opening  27  of the slide tab  28  creates a positive engagement between the lock release wand  80  and the lock  12  such that the lock release wand  80  does not separate from the lock  12  even when pulling down on the lock release wand  80 . 
         [0080]    Once the shade  10  is in the desired position, the user rotates the lock release wand  80  in a clockwise direction which allows the spring  30  to urge the slide tab  28  back to the locking position. Further rotation of the lock release wand  80  pulls the second frustoconical surface  100  out of the opening  27  in the slide tab  28  and allows the user to pull down on and remove the lock release wand  80 . 
       Top-Down, Bottom-Up Shade 
       [0081]      FIGS. 16 and 17  show a top-down, bottom-up cellular shade  10 ′. This general type of shade  10 ′ is described in the aforementioned U.S. Pat. No. 7,740,045 “Spring Motor and Drag Brake for Drive for Coverings for Architectural Openings”, issued Jun. 22, 2010, which is hereby incorporated herein by reference. 
         [0082]    The shade  10 ′ includes a head rail  14 ′, a movable intermediate rail  15 ′, a movable bottom rail  16 ′, and a cellular shade structure  18 ′ suspended from the intermediate rail  15 ′ and attached to both the intermediate rail  15 ′ and the bottom rail  16 ′. 
         [0083]    There is a first set of lift cords  108 ′ that extend from the head rail  14 ′ to the intermediate rail  15 ′. These first lift cords  108 ′ have first ends attached to lift stations  21 ′ located in the head rail  14 ′ and second ends attached to the intermediate rail  15 ′. These first lift cords  108 ′ are raised and lowered with the rotation of a first lift rod  23 ′. 
         [0084]    There is a second set of lift cords  110 ′ that extend from the head rail  14 ′ to the bottom rail  16 ′. These second lift cords  110 ′ have first ends attached to lift stations  20 ′ in the headrail  14 ′, extend through the intermediate rail  15 ′ and through the covering  18 ′ and have second ends attached to the bottom rail  16 ′. These second lift cords  110 ′ are raised and lowered with the rotation of a second lift rod  22 ′. Other components include spring motors with drag brakes  24 ′, as described below. 
         [0085]    The first lift rod  23 ′ extends through the lift stations  21 ′. A spring motor with drag brake  24 ′ is functionally attached to the first lift rod  23 ′ to provide an assisting force when raising the intermediate rail  15 ′ of the shade  10 ′. When the first lift rod  23 ′ rotates, the lift spools on the lift stations  21 ′ also rotate, and the lift cords  108 ′ wrap onto or unwrap from the lift stations  21 ′ to raise or lower the intermediate rail  15 ′. 
         [0086]    The second lift rod  22 ′ extends through the lift stations  20 ′ in the headrail  14 ′. A spring motor with drag brake  24 ′ is functionally attached to the second lift rod  22 ′ to provide an assisting force when raising the bottom rail  16 ′ of the shade  10 ′. When the second lift rod  22 ′ rotates, the lift spools on the lift stations  20 ′ also rotate, and the lift cords  110 ′ wrap onto or unwrap from the lift stations  20 ′ to raise or lower the bottom rail  16 ′. 
         [0087]    This arrangement results in two sets of lift cords  108 ′,  110 ′ extending adjacent to each other, with both of these two sets of lift cords  108 ′,  110 ′ being exposed as the intermediate rail  15 ′ travels down toward the bottom rail  16 ′. 
         [0000]    Arrangement with Intermediate Rail Riding on Lift Cords of Lower Rail: 
         [0088]      FIGS. 18-20  show a top-down/bottom-up cellular shade  10 *, which eliminates one of the sets of lift cords from the embodiment of  FIG. 16 . As explained in more detail below, a single set of lift cords  108 * extends from the head rail  14 *, through the intermediate rail  15 *, through the covering  18 *, and on down to the bottom rail  16 *. 
         [0089]    The shade  10 * of  FIGS. 18-20  includes a head rail  14 *, an intermediate rail  15 *, a bottom rail  16 *, and a cellular shade structure  18 * suspended from the intermediate rail  15 * and attached to both the intermediate rail  15 * and the bottom rail  16 *. 
         [0090]    Single lift cords  108 * are attached to the head rail  14 *, extend through a set of windlass assemblies  112 * in the intermediate rail  15 *, and then on through openings in the cellular shade  18 *, to terminate at lift stations  20 * housed in the bottom rail  16 *. A lift rod  22 * extends through the lift stations  20 * in the bottom rail  16 *. When the lift rod  22 * rotates, the lift spools on the lift stations  20 * also rotate, and the lift cords  108 * wrap onto or unwrap from the spools on the lift stations  20 * to raise or lower the bottom rail  16 *. A spring motor with drag brake  24 * is functionally attached to the lift rod  22 * to provide an assisting force when raising the bottom rail  16 * and to hold the bottom rail  16 * in place when released by the user. 
         [0091]    A connecting rod (or lift rod)  23 * in the intermediate rail  15 * extends through the locking mechanism  12 * and through the windlass assemblies  112 * to functionally interconnect them as described later. 
         [0092]    The spring motor with drag brake  24 * in the movable bottom rail  16 * of  FIGS. 19 and 20  is identical to the spring motor with drag brake  24 ′ of  FIG. 17 , including the possibility of incorporating overpowered or underpowered springs, as well as the possibility of incorporating a spring with a negative power curve as has already been discussed. The lift stations  20 * of  FIGS. 19 and 20  are substantially identical to the lift stations  20 ′,  21 ′ of  FIG. 17 , which has already been described. Finally, the locking mechanism  12 * of  FIGS. 19 and 20  is substantially identical in design and operation to the locking mechanism  12  of  FIG. 3 , which already has been described. 
         [0093]    The windlass assemblies  112 * shown in  FIGS. 19 and 20  are shown in more detail in  FIGS. 21-26 . Each windlass assembly  112 * includes a windlass (or capstan)  116 * and a windlass housing  118 *. The windlass (or capstan)  116 * is a spool that rotates within the windlass housing  118 *. The windlass housing  118 * is a substantially rectangular housing with a top wall  120 *, a front wall  122 *, a rear wall  124 *, a right wall  126 *, and a left wall  128 *, which define a hollow cavity  130 * for rotationally housing the windlass spool  116 *. The windlass spool  116 * is assembled to the windlass housing  118 * through the bottom of the windlass housing  118 * as discussed below. 
         [0094]    The right and left walls  126 *,  128 * include arms  132 *,  134 * respectively, which, in turn, define ramps  136 *,  138 * respectively which rotationally support the windlass spool  116 *, as described in more detail later. The top wall  120 * defines a cord entry port  140 *, and the bottom of the windlass housing  118 * defines a cord outlet port  142 *. Finally, a biasing member  144 *, resembling a paddle or a flat finger, projects downwardly inside the cavity  130 *, adjacent the windlass spool  116 *, as best appreciated in  FIGS. 21 ,  23 , and  24 . As explained in more detail later, the purpose of the biasing member  144 * is to press the windings of the lift cord  108 * against the ribs  145 *(See  FIG. 23 ) of the windlass spool  116 * to prevent slippage between the lift cord  108 * and the windlass spool  116 *, that is, to prevent the possibility of the lift cord  108 * surging the windlass spool  116 *. 
         [0095]    Referring to  FIGS. 23 and 25 , the windlass spool  116 * is a hollow, cylindrical body with an internal bore  146 * having a non-circular profile. In this particular embodiment, it has a “V” projection profile. The connecting rod  23 * has a “V” notch and it is sized to nearly match the internal profile of the bore  146 *, with the “V” projection of the bore  146 * being received in the “V” notch of the connecting rod  23 *, such that the windlasses (or capstans)  116 * of the windlass assemblies  112 * and the connecting rod  23 * are positively engaged to rotate together. The windlass spool  116 * defines two coaxial frustoconical surfaces  152 *,  154 * tapering from a larger diameter at the end to a smaller diameter toward the center, and these surfaces are interconnected by a coaxial, generally cylindrical surface with a plurality of friction-enhancing, spaced apart ribs  145 *. 
         [0096]    To assemble the windlass assembly  112 *, a first end of the lift cord  108 * is fed up through the cord exit port  142  in the bottom of the housing  118 * into the cavity  130 * of the housing  118 *, then is pulled downwardly out through the open bottom of the housing  118 * and is wound one or more times around the central portion of the windlass spool  116 *(as shown in  FIG. 25 ) and then is fed back into the open cavity  130 * and upwardly through the entry port  140 * out of the windlass housing  118 * and is secured to the head rail  14 ′. The windlass spool  116 * is then installed in the windlass housing  118 * by pushing the windlass spool  116 * upwardly into the open cavity  130 * through the bottom of the windlass housing  118 *. The stub shafts  148 *,  150 *(See  FIGS. 23 and 26 ) of the windlass spool  116 * slide up the ramps  136 *,  138 * and push outwardly against the arms  132 *,  134 *, gradually prying them apart as the windlass spool moves upwardly until the windlass spool  116 * clears the tops of the arms  132 *,  134 *, at which point the arms  132 *,  134 * snap back to their original positions, securing the windlass spool  116 * in the housing  118 * as shown in  FIGS. 21 ,  22  and  26 . The second end of the lift cord  108 * is then extended through the covering  18 * and is secured to the respective lift station  20 * in the bottom rail  16 *. 
         [0097]    The connecting rod  23 * is inserted through both windlass assemblies  112 * and through the splined sleeve  32 * of the locking mechanism  12 *, as shown in  FIG. 19 . 
         [0098]    As was discussed with respect to the locking mechanism  12  of  FIGS. 3-5 , when the user squeezes the slide tab  70 * and fixed tab  42 * together, the wing that is fixed to the slide tab  70 * moves away from the splined portion of the splined sleeve  32 *, unlocking the locking mechanism  12 * and allowing rotation of the connecting rod  23 * and associated windlass spools  116 *. 
       The Operation of the Shade  10 * is as Follows: 
       [0099]    To raise the bottom rail  16 *, the user grabs the bottom rail  16 *(See  FIG. 20 ) and lifts it up. The spring motor with drag brake  24 * located in the bottom rail  16 * assists in raising the bottom rail  16 *. The spring motor  24 * causes rotation of the spools in the lift stations  20 * in order to wind up any excess lift cord  108 * onto the spools as the bottom rail  16 * is raised. When the user releases the bottom rail  16 *, the drag brake portion of the spring motor with drag brake  24 * holds the bottom rail  16 * in place. Since the spools in the lift stations  20 * rotate together, they keep the bottom rail  16 * horizontal as it travels up and down. 
         [0100]    To lower the bottom rail  16 *, the user pulls down on the bottom rail  16 *. The lift cords  108 * are attached to the head rail  14 *, are cinched tightly around their respective windlasses (or capstans)  116 *, and extend to the spools on the lift stations  20 * in the bottom rail  16 *. Since the locking mechanism  12 * has not been released, the connecting rod  23 * is locked against rotation, as are the windlass spools  116 *, so the intermediate rail  15 * remains stationary. The lift cords  108 * unwind from the lift stations  20 * in the bottom rail  16 *, and the bottom rail  16 * is lowered. Again, once the user releases the bottom rail  16 *, the drag brake portion of the spring motor with drag brake  24 * holds the bottom rail  16 * in position. 
         [0101]    To raise the intermediate rail  15 *, the user squeezes the tabs  42 *,  70 * together, which releases the splined sleeve  32 * for rotation. Since the connecting rod  23 * and the windlass spools  116 * are keyed to the splined sleeve  32 *, they also can rotate. If the user lifts up on the intermediate rail  15 * while squeezing the tabs  42 *,  70 * together, the windlass spools  116 * will rotate in their respective windlass housings  118 *, travelling upwardly along the lift cord  108 * as they transfer a portion of the lift cord  108 * that is above the windlass assemblies  112 * to below the windlass assemblies  112 *, so the intermediate rail  15 * also travels upwardly along the cords  108 *. Once the intermediate rail  15 * is in the desired location, the user releases the tabs  42 *,  70 * of the locking mechanism  12 *, which locks the splined sleeve  32 *, and therefore the connecting rod  23 * and the windlass assemblies  112 *, against further rotation, thereby locking the intermediate rail  15 * in place. 
         [0102]    To lower the intermediate rail  15 *, the procedure is the reverse of that for raising the intermediate rail  15 * described above. The user squeezes together the tabs  42 *,  70 * of the locking mechanism  12 *, which releases the splined sleeve  32 * for rotation, which allows the connecting rod  23 * and the windlass assemblies  112 * to rotate. While squeezing together the tabs  42 *,  70 *, the user pulls down on the intermediate rail  15 *. The windlass spools  116 * rotate in the opposite direction, and the intermediate rail  15 * travels downwardly along the lift cords  108 *. Once the intermediate rail  15 * is in the desired position, the user releases the tabs  42 *,  70 * of the locking mechanism  12 *, which locks the intermediate rail  15 * in place. Since the windlass spools (or capstans)  116 * are tied together by the rod  23 * and rotate together, they keep the intermediate rail  15 * horizontal as it travels up and down. 
         [0103]    It should be noted that the bottom rail  16 * remains in position as the intermediate rail  15 * is raised and lowered, since the position of the bottom rail  16 * is determined by the rotation of the spools on the lift stations  20 *, not by the position of the intermediate rail  15 *. 
         [0104]    The tapered surfaces  152 *,  154 * on the windlass spools  116 * ensure that the lift cords  108 * remain centered on the windlass spools  116 *, and the ribs  145 * on the windlass spools  116 * together with the biasing leg  144 * which presses the lift cord  108 * against the ribs  145 * ensures that the cord  108 * does not slip relative to the windlass spools  116 *, so the cord  108 * serves as a type of indexing mechanism. This helps ensure that the intermediate rail  15 * remains horizontal as it travels up and down along the lift cords  108 *. 
       Alternate Embodiment of a Windlass 
       [0105]      FIGS. 27-31  show an alternate embodiment of a windlass assembly  112 ** which may be used in the cellular shade of  FIGS. 18-20  instead of the windlass assembly  112 *. As best appreciated in  FIG. 28 , the windlass assembly  112 ** includes a windlass spool (or capstan)  116 **, a windlass housing  118 **, and a windlass housing cover  119 **. 
         [0106]    The most important difference between this windlass assembly  112 ** and the windlass assembly  112 * described above is that this windlass assembly  112 ** does not have a biasing member  144 *. Instead, and as best appreciated in  FIGS. 28 ,  29 ,  30  and  31 , the windlass housing  118 ** and the windlass housing cover  119 ** each have semi-circular surfaces  156 **,  158 ** which define circumferential guiding grooves  160 **,  162 ** respectively, which tightly guide the lift cord  108 * around the windlass spool  116 **, pressing the lift cord  108 * against the ribs  145 ** (See  FIGS. 28 and 31 ) of the windlass spool  116 ** to prevent slippage between the lift cord  108 * and the windlass spool  116 **, that is, to prevent the possibility of the lift cord  108 * surging the windlass spool  116 **. 
         [0107]    The operation of the cellular shade  18  using this second embodiment of a windlass assembly  112 ** is identical to the operation described earlier with respect to the first embodiment of the windlass assembly  112 *. 
         [0000]    Alternate Embodiment of a Cellular Shade with a Drive with a Lock Mechanism 
         [0108]      FIGS. 32-38  depict an embodiment of a cellular shade  10 ′, similar to the shade  10  of  FIG. 1 , except that an indexing mechanism  164 ′ is used to rotate the lift rod  22  instead of using a spring motor. (It should be noted that a windlass and cord could be substituted as an alternative indexing mechanism.) 
         [0109]      FIGS. 32 ,  33 , and  34  show the cellular shade  10 ′ which includes a top rail  14 ′, bottom horizontal movable rail  16 ′, a cellular shade structure  18 ′, and an anchoring ledge  166 ′. It should be noted that the anchoring ledge  166 ′ may be part of the frame of the window opening and serves the purpose of providing an anchoring point to secure a bead chain  168 ′ which extends from the top rail  14 ′ to the anchoring ledge  166 ′. 
         [0110]    As shown in  FIG. 34 , the bottom rail  16 ′ houses a slide lock mechanism  12 , lift stations  20 , and a lift rod  22 , which are identical to the corresponding items in the cellular shade  10  of  FIG. 3 . The most important difference is the absence of the spring motor  24  (See  FIG. 3 ) which has been replaced by the indexing mechanism  164 ′ (See  FIG. 34 ), as explained in more detail below. 
         [0111]    Referring to  FIGS. 35-38 , the indexing mechanism  164 ′ includes a bottom rail end cap  170 ′ and a sprocket  172 ′, and utilizes the bead chain  168 ′ to rotate the lift rod  22  when the bottom rail  16 ′ is raised or lowered, as explained later. The sprocket  172 ′ and lift rod  22  cause the lift spools  20  to rotate together, which keeps the rail  16 ′ horizontal as it travels up and down. 
         [0112]    Referring to  FIG. 37 , the bottom rail end cap  170 ′ defines ramped approaches  174 ′,  176 ′ to guide the bead chain  168 ′ to the sprocket  172 ′, as may also be appreciated in  FIG. 35 . The end cap  170 ′ also includes flat projections  178 ′,  180 ′,  182 ′, and  184 ′ which project inwardly from the end cap  170 ′ and which are used to releasably secure the end cap  170 ′ to the bottom rail  16 ′. Finally, the end cap  170 ′ also includes a support shaft  186 ′ with an enlarged diameter, barbed end  188 ′. The support shaft  186 ′ rotationally supports the sprocket  172 ′, as shown in  FIG. 36 . 
         [0113]      FIG. 38  shows the sprocket  172 ′ which includes a plurality of semi-circular, circumferentially-arranged, evenly-spaced and alternatingly-opposed cavities  190 ′ designed to receive and engage the beads of the bead chain  168 ′ as the indexing mechanism  164 ′ is raised or lowered together with the bottom rail  16 ′. The hollow shaft  192 ′ of the sprocket  172 ′ has a non-cylindrical cross-sectional profile  194 ′ which matches up with a similarly shaped cross-sectional profile on the lift rod  22  for positive rotational engagement between the sprocket  172 ′ and the lift rod  22 . The portion of the hollow shaft  192 ′ that is located inside the sprocket “teeth”  190 ′ has a reduced inside diameter portion  193 ′ (See  FIG. 36 ), which helps retain the sprocket  172 ′ onto the shaft  186 ′ as describe below. 
         [0114]    To assemble the indexing mechanism  164 ′ to the shade  10 ′, the sprocket  172 ′ is first rotationally mounted to the shaft  186 ′ on the end cap  170 ′ by pushing the sprocket  172 ′ onto the shaft  186 ′ and compressing the barbed end  188 ′ until the reduced diameter portion  193 ′ of the sprocket  172 ′ passes the barbed end  188 ′, at which point the barbed end  188 ′ snaps open to its non-compressed position, locking the sprocket  172 ′ onto the shaft  186 ′, as shown in  FIG. 36 . Then, one end of the bead chain  168 ′ is fed through the ramped approach  174 ′ (See  FIG. 37 ) and the sprocket  172 ′ is manually rotated to feed the bead chain  168 ′ around the sprocket  172 ′, with the beads on the bead chain  168 ′ engaging the cavities  190 ′ on the sprocket  172 ′. The bead chain  168 ′ wraps around the sprocket  172 ′ and then exits the end cap  170 ′ via the ramped approach  176 ′. The indexing mechanism  164 ′ is then pressed onto the end of the bottom rail  16 ′, with the lift rod  22  being inserted into and engaging the non-cylindrical cross-sectional profile  194 ′ of the shaft  192 ′ of the sprocket  172 ′. The end of the bead chain  168 ′ is then secured to the anchoring ledge  166 ′ such that the bead chain  168 ′ is fairly taut between the top rail  14 ′ and the anchoring ledge  166 ′. 
       Operation: 
       [0115]    To raise the shade  10 ′ the lock  12  is unlocked, as explained earlier with respect to the embodiment described in  FIGS. 1-3 , and the operator manually raises the bottom rail  16 ′ to the desired height. As the bottom rail  16 ′ is raised, the bead chain  168 ′ rotates the sprocket  172 ′ in a first direction, which also rotates the lift rod  22  and the lift stations  20 , so as to gather up the lift cords (not shown) onto the spools of the lift stations  20  in the movable rail  16 ′. When the operator releases (lets go of) the lock mechanism  12 , it locks the lift rod  22  against further rotation, holding the bottom rail  16 ′ where it was released, as described earlier with respect to the shade  10  of  FIGS. 1-3 . 
         [0116]    To lower the shade  10 ′, the operator again unlocks the lock  12  and lowers the bottom rail  16 ′ to the desired position. As the bottom rail  16 ′ is lowered, the bead chain  168 ′ rotates the sprocket  172 ′ in the opposite direction which then also rotates the lift rod  22  and the lift stations  20  in the opposite direction, unwinding the lift cords (not shown) from the spools of the lift stations  20 . When the operator releases (lets go of) the lock mechanism  12 , it locks the lift rod  22  against further rotation, holding the bottom rail  16 ′ where it was released. 
         [0117]      FIG. 39  shows yet another embodiment of a cellular shade  10 ″ which is very similar to the shade  10 ′ described above, except that it has two indexing mechanisms  164 ′, one on each end of the bottom rail  16 ′, which ride along their corresponding bead chains  168 ′. Other than this difference, the shade  10 ″ is identical to the shade  10 ′ and operates in the same manner. It should be obvious that other indexing mechanisms may be used instead of the bead chain and sprocket mechanism shown in the figures. For instance, a rack and pinion arrangement may be used in which the rack replaces the bead chain and the pinion replaces the sprocket. Any indexing mechanism that is used to rotate the lift rod without the need for a motor may be used to replace the bead chain and sprocket mechanism described above. 
         [0000]    Two Movable Rail Shade with Automatic Variable Stroke Limiter 
         [0118]    While the embodiment shown in  FIGS. 18-20  is one way to arrange for raising and lowering two (or more) movable rails without the addition of a second set of lift cords  110 ′ as in  FIG. 16 , another way to achieve this result is shown in  FIGS. 40-44 . 
         [0119]      FIGS. 40-44  are schematics of a shade  200  with two movable rails in which the upper rail is suspended by lift cords that extend to fixed points above the upper rail, and the lower rail is suspended by lift cords that extend down from the upper rail. 
         [0120]    With this type of arrangement, the issue arises that if the lower rail lift cords are long enough so the lower movable rail can extend to the bottom of the architectural opening when the upper rail is at the top of the opening, then the lower movable rail may extend below the bottom of the architectural opening when the upper rail moves down. Of course, this is not desirable. For that reason, an automatic variable stroke limiter has been incorporated into this design. 
         [0121]    As explained in more detail later, the automatic variable stroke limiter controls the overall length of the shade  200  so that the bottom rail will not extend beyond a desired position, such as beyond the bottom of the opening, regardless of the position of the upper movable rail. 
         [0122]    Referring to  FIG. 40 , the shade  200  includes a head rail  202 , an upper movable rail  204 , and a lower movable rail  206 . Extendable covering materials  208  (See  FIG. 44 ) such as a pleated shade material or a plurality of slats supported by ladder tapes may be secured to the upper and lower rails  204 ,  206 , so that, when the rails move up and down, they extend and retract the covering materials. For example, in  FIG. 44 , the covering material  208  extends between the upper movable rail  204  and the lower movable rail  206 . As another possibility, a first covering material  208  could extend from the head rail  202  to the upper movable rail  204 , and a second covering material  208  could extend from the lower movable rail  204  to the bottom of the architectural opening. 
         [0123]    The upper movable rail  204  houses first and second cord spools  212 ,  214  mounted for rotation together on an elongated upper rail lift rod  216 . The cord spools  212 ,  214  may be located anywhere along the upper rail lift rod that is desired. For example, if a pleated shade material is extending between the head rail  202  and the upper movable rail  204 , the cord spools  212 ,  214  will be located inwardly far enough to ensure that the pleated shade material remains under control and does not “blow out”. If no covering material is extending between the head rail  202  and the upper movable rail  204 , then it may be desirable to move the cord spools  212 ,  214  further outwardly so the cords that wrap around them do not interfere with the user&#39;s line of sight. 
         [0124]    First and second upper rail lift cords  218 ,  220  have their first ends secured to the head rail  202  at fixed points  218   a ,  220   a  and their second ends secured to the cord spools  212 ,  214 . As an alternative, the head rail  202  may be omitted and the first set of lift cords may be secured directly to the frame of the window opening at the fixed points  218   a ,  220   a . It also should be noted that the fixed points  218   a ,  220   a  may alternatively be points on a movable rail located above the upper movable rail. 
         [0125]    In these schematics, the angled arrows on the cord spools (such as the arrow  222  on the cord spool  212  in  FIG. 40 ) indicate the extent to which the lift cord is wrapped onto the cord spool. If the lift cord is shown coming off of the respective spool at the end near the tip of the arrow, that means it is fully wound onto that spool. If it is shown coming off the respective spool at the opposite end, that means it is unwound from that spool. 
         [0126]    For example, in  FIG. 40 , the lift cord  218  is fully wrapped onto the cord spool  212 , while in  FIG. 41  the same lift cord  218  is fully unwrapped from the cord spool  212 , and in  FIG. 42  the same lift cord  218  is approximately half way wound onto the cord spool  212 . 
         [0127]    Referring again to  FIG. 40 , two counterwrap cord spools  224 ,  226  are mounted on the same upper rail lift rod  216 , between the first and second cord spools  212 ,  214 , for rotation together with the lift rod  216 . These counterwrap cord spools  224 ,  226  may be located anywhere along the lift rod  216 , as desired. Lower rail lift cords  238 ,  240  are counterwrapped onto these additional cord spools  224 ,  226  (wrapped in the direction opposite to the direction of the wrap on the first and second cord spools  212 ,  214 ) so that, as the upper lift rod  216  rotates to wind up the upper rail lift cords  218 ,  220  onto the first and second lift spools  212 ,  214 , it causes the lower rail lift cords  238 ,  240  to unwind from their respective counterwrap spools  224 ,  226 . Similarly, as the upper rail lift rod  216  rotates in the opposite direction, to unwind the upper rail lift cords  218 ,  220  from their lift spools  212 ,  214 , it causes the counterwrapped lower rail lift cords  238 ,  240  to wrap onto the counterwrap spools  224 ,  226 . 
         [0128]    It should be noted that, while the lift spools  212 ,  214  and counterwrap spools  224 ,  226  are shown as separate pieces mounted on the upper lift rod  216  and individually movable along that lift rod  216 , it would be possible for two (or even more) of the cord spools to be made as a single piece. Also, while the first and second upper rail lift cords  218 ,  220  are shown in this schematic as being separate from the first and second counterwrap cords  238 ,  240 , it is understood that the first upper rail lift cord  218  and the first counterwrap cord  238  could actually be a single cord, and, similarly that the second upper rail lift cord  220  and the second counterwrap cord  240  could be a single cord. 
         [0129]    A motor  228 , such as the spring motor  24  of  FIG. 3 , also is mounted on the upper rail lift rod  216  to assist in wrapping the lift cords  218 ,  220  onto their respective cord spools  212 ,  214  when raising the upper movable rail  204 . (The motor  228  could alternatively be a battery-powered electric motor.) 
         [0130]    The shade  200  also includes a lower movable rail  206  which houses two cord spools  230 ,  232  mounted on a lower rail lift rod  236  for rotation together with the rod  236 . As with the previous cord spools, these lower rail cord spools  230 ,  232  may be located anywhere along the lower rail lift rod  236 . The two lower rail lift cords  238 ,  240  have their first ends secured to the counterwrap cord spools  224 ,  226 , respectively, and their corresponding second ends secured to the corresponding cord spools  230 ,  232  on the lower movable rail  206 . The vertical line  242  shown on the left side of  FIGS. 40-43  represents the full length of the window opening on which the shade  200  is installed. 
         [0131]    Referring to  FIG. 40 , the shade  200  is shown with both the upper movable rail  204  and the lower movable rail  206  in the fully retracted positions. That is, the upper movable rail  204  is all the way up against the head rail  202 , and the lower movable rail  206  is all the way up against the upper movable rail  204 . When the rails are in this position, the first and second upper rail lift cords  218 ,  220  are fully wrapped onto their respective first and second cord spools  212 ,  214 . The lower rail lift cords  238 ,  240  are fully wrapped onto their respective lower rail cord spools  230 ,  232  and fully unwrapped from their respective counterwrap cord spools  224 ,  226 . 
         [0132]    The user now may lower the upper rail until it is fully extended, while the lower movable rail  206  remains all the way up against the upper movable rail  204 , as shown in  FIG. 41 . In this instance, as the upper movable rail  204  is lowered, the first and second upper rail lift cords  218 ,  220  unwrap from their corresponding first and second cord spools  212 ,  214  and, as they do so, they cause the upper rail lift rod  216  to rotate, which causes the counterwrap cord spools  224 ,  226  to rotate, which causes the lower rail lift cords  238 ,  240  to wrap onto the counterwrap cord spools  224 ,  226 . Since the lower rail  206  already is abutting the upper rail  204  and therefore cannot move up any further relative to the upper rail  204 , as the user pulls down on the upper movable rail  204 , he is also pushing down on the abutting lower movable rail  206 , so the lower rail lift cords  238 ,  240  unwrap from the lower rail cord spools  230 ,  232  as they wrap onto the counterwrap cord spools  224 ,  226 . 
         [0133]    In  FIG. 41 , the upper movable rail  204  is in the fully extended position, with the upper rail lift cords  218 ,  220  fully unwound from their spools  212 ,  214 . The lower movable rail  206  is abutting the upper movable rail  204 , with the lower rail lift cords  238 ,  240  fully wound onto the counterwrap spools  224 ,  226  and fully unwound from the lower rail spools  230 ,  232 . The total length of the shade  200  matches the length of the opening (depicted by the arrow  242 ), so the lower movable rail  206  is at the bottom of the architectural opening. The lower movable rail  206  cannot be lowered any further relative to the upper movable rail  204  because the lower rail lift cords  238 ,  240  are already fully unwrapped from the lower rail cord spools  230 ,  232 . 
         [0134]    It might be suggested that the lower rail lift cords  238 ,  240  could unwrap from the counterwrap cord spools  224 ,  226  to further lower the lower movable rail  206 . However, in order to unwrap the lower rail lift cords  238 ,  240  from the counterwrap cord spools  224 ,  226  the counterwrap spools  224 ,  226  would have to rotate together with the upper rail lift rod  216  and the first and second cord spools  212 ,  214 , which would wind the upper rail lift cords  218 ,  220  onto the first and second cord spools  212 ,  214  to raise the upper rail  204 . Thus, rotating the upper lift rod  216  to extend the lower rail lift cords  238 ,  240  would also retract the upper rail lift cords  218 ,  220  by the same distance, such that the lower movable rail  206  would remain stationary relative to the head rail  202 ; it would not drop below the length of the opening (depicted by the arrow  242 ). 
         [0135]    Referring now to  FIG. 42 , the user has raised the upper movable rail  204  to an intermediate position approximately half way between the fully retracted position (shown in  FIG. 40 ) and the fully extended position (shown in  FIG. 41 ). The upper rail lift cords  218 ,  220  are approximately half way wrapped onto their corresponding first and second cord spools  212 ,  214 . The lower rail lift cords  238 ,  240  are approximately half way unwrapped from the counterwrap cord spools  224 ,  226  on the upper movable rail  204  and are fully unwrapped from the lower rail cord spools  230 ,  232 . Again, the lower movable rail  206  cannot be lowered any farther than the bottom of the opening  242 . The lower rail cord spools  230 ,  232  already are fully unwrapped. Therefore, any lengthening of the lower rail extension cords  238 ,  240  would have to come from their unwrapping from the counterwrap cord spools  224 ,  226 . However, these counterwrap cord spools  224 ,  226  are tied to the first and second cord spools  212 ,  214  by the upper rail lift rod  216 , so any unwrapping of the lower rail lift cords  238 ,  240  from the counterwrap cord spools  224 ,  226  would only occur along with corresponding wrapping of the upper rail lift cords  218 ,  220  onto their corresponding first and second cord spools  212 ,  214 , thus shortening these upper rail lift cords  218 ,  220  by the same distance the lower rail lift cords  238 ,  240  are lengthened. Thus, while the lower movable rail  206  would move some distance away from the upper movable rail  204 , the upper movable rail  204  would be moving the same distance toward the head rail  202 , resulting in the lower movable rail  206  remaining in the same position relative to the fixed points  218   a ,  220   a.    
         [0136]    Comparing  FIGS. 42 and 43 , it may be appreciated that in both figures the lower rail lift cords  238 ,  240  are wrapped halfway onto the counterwrap cord spools  224 ,  226 . In  FIG. 42 , the lower rail lift cords are fully unwrapped from the lower rail spools  230 ,  232 , so the balance of the lower rail lift cords  238 ,  240  spans the distance between the upper movable rail  204  and the lower movable rail  206 . When the lower movable rail  206  is raised to the position shown in  FIG. 43 , where it abuts the upper movable rail  204 , the counterwrap cord spools  224 ,  226  do not move, so no more cord is wrapped onto them. All the excess of the lower rail lift cords  238 ,  240  resulting from the raising of the lower movable rail  206  wraps onto the lower rail cord spools  230 ,  232 , which, in  FIG. 43 , are shown to be half-way wrapped with the lower rail lift cords  238 ,  240 . 
         [0137]    In this embodiment, the motors  228 ,  234  provide at least enough force to wrap any excess cords onto their respective spools as the movable rails are raised. The motors  228 ,  234  may also provide additional force to aid the user in lifting the movable rails so as to reduce the catalytic force required from the user to raise the movable rails. In this embodiment, the forces acting to raise the shade  200  (essentially the force provided by the motors  228 ,  234 ) are close enough to forces acting to lower the shade  200  (essentially the force of gravity acting on the components) that the friction and inertia in the system are sufficient to prevent the rail from moving up or down once the rail is released by the user. 
         [0138]    As an alternative embodiment, the number  228 , which represents a motor in the upper movable rail  204 , could instead represent a lock that is operable by the user, such as the lock  12  shown in  FIG. 1 . In that case, if the user begins with the shade  200  in the position shown in  FIG. 42 , when the user releases the lock in the upper movable rail  204  and raises the upper movable rail from the position shown in  FIG. 41 , the lower rail lift cords  238 ,  240  will cause the counterwrap spools  224 ,  226  to unwind, which will rotate the upper rail lift rod  216  and the upper rail lift spools  212 ,  214 , winding up the upper rail lift cords  218 ,  220  onto the spools  212 ,  214 . Then, when the user releases the upper rail  204 , the lock will hold the upper rail  204  in position. Similarly, if the user begins with the shade  200  in the position shown in  FIG. 42 , when the user releases the lock in the upper movable rail  204  and pushes downwardly on the upper rail  204 , the upper rail lift cords  218 ,  220  will pull on the upper rail lift spools  212 ,  214 , causing those spools to unwind, which, in turn, will cause the lower rail lift cords  238 ,  240  to wind up onto the counterwrap spools  224 ,  226 . 
         [0139]    Of course, either or both of the upper and lower rails  204 ,  206  could have both a motor and a releasable lock functionally connected to their respective lift rods  216 ,  236 . 
         [0140]      FIG. 44  shows a shade  200 * which is similar to the shade  200  of  FIGS. 40-43  except that it shows the covering material  208  and has brakes  210 ,  211  acting on their corresponding lift rods  216 ,  236 . The brakes  210 ,  211  and their corresponding motors  228 ,  234  may be a combination spring motor and drag brake, similar to the spring motor and drag brake  24 * of  FIG. 20  to selectively stop the rotation of their corresponding lift rods  216 ,  236 . A brake could be used on one or more of the lift rods, as needed, depending upon the forces involved. 
         [0141]    It will be obvious to those skilled in the art that additional movable rails may be added, with each movable rail being suspended from the next adjacent movable rail above it, and with each pair of adjacent movable rails having its corresponding automatic variable stroke limiter to ensure that the overall length of the resulting shade does not exceed a desired length, which is usually the length of the opening to which it is mounted. 
         [0142]    It should also be noted that the lift mechanisms in either of the movable rails may alternatively make use of other known mechanisms that provide for the cord spools to rotate together. For instance, U.S. Pat. No. 7,117,919 “Judkins” shows interconnected spools and spring motors. U.S. Pat. No. 7,093,644 “Strand” shows gear driven spools. 
         [0143]    It also will be obvious to those skilled in the art that additional modifications may be made to the embodiments described above without departing from the scope of the invention as claimed.