You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
RELATED APPLICATIONS  
       [0001]    This application claims priority to U.S. provisional application 60/369,996 filed on Apr. 3, 2002, which is incorporated by reference in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention generally relates to window coverings and treatments that include a plurality of individual cells that are variably adjustable between a collapsed position and an expanded position. More specifically, the present invention relates to the cells of a multi-cell window covering and a method for manufacturing the cells of a multi-cell window covering.  
           [0004]    2. Description of the Related Art  
           [0005]    Partly in response to the limitations inherent in traditional window coverings like venetian blinds, fresh window coverings and treatments, such as multi-cellular shades, were developed and welcomed by consumers. In the broad sense, a cellular shade is a window covering having a plurality of cells arranged adjacent to one another. The adjacent cells are bonded at their edges to form a complete sheet for the window covering. These multi-cellular shades provide significant insulating value, uniform light diffusion and a desirable aesthetic presentation, but they typically have no view-through capability. Unlike traditional venetian blinds, which provide easy modulatable view-through and light control by simply adjusting the orientation of the horizontally disposed slats or vanes, traditional multi-cellular shades are not capable of separating the plurality of cells, thus preventing a view-through option. Therefore, in order for a person to see through a window that is outfitted with a traditional multi-cellular shade, it is necessary to collectively raise and gather the plurality of cells, i.e., raise the entire window covering. However, raising the whole cellular window shade is laborious and time consuming.  
           [0006]    In light of the advantages of venetian blind and multi-cellular window shades, a hybrid window covering was developed that provides the characteristics of both a venetian blind and a multi-cellular window covering. This hybrid window covering includes a plurality of cells arranged parallel to one another. Each cell has at least one side, and a joint that unites adjacent sides of each cell. The adjacent sides are pivotable about the joint such that each cell is variably adjustable between a collapsed position and an expanded position. By collapsing and expanding the cells, the window covering can achieve adjustable light-control, modulatable view-through, light diffusion, and excellent insulation value, all in an aesthetically pleasing design.  
           [0007]    Included in this hybrid window covering is a means for variably adjusting the cells between the collapsed position, where adjacent cells are separated, and the expanded position, where adjacent cells contact one another. The adjustment means typically includes a pair of cords that engage and actuate the cells between the collapsed and expanded positions. Due to the structure of the cells, the relative position of the cords in each pair is not fore-and-aft (i.e., perpendicular to the plane of the window covering), as in a conventional venetian blind, but rather is parallel to the plane of the window covering for central, balanced lifting and lowering of the upper and lower portions of each cell. A series of beads or other suitable attachment elements are secured to the cords and are engaged with one or more surfaces of the cells during manufacture.  
           [0008]    [0008]FIG. 1 of the drawings illustrates an exemplary window treatment employing the cell and cord arrangement described above. Note that in location “A,” the upper surface of the cell includes a relatively small bead-engaging aperture aligned vertically with a larger cord clearance aperture on the lower surface of the cell. Alternatively, at location “B,” the relatively small bead-engaging aperture is located on the lower surface of the cell and the larger cord-clearance aperture is located on the upper surface of the cell. Manufacturing alternating apertures on the upper and lower surfaces of a pre-manufactured, multi-surface cell is generally impractical, as it would require a separate manufacturing operation on the upper and lower surfaces of the cell. The difference in aperture size alone, regardless of the orientation between dissimilar apertures, renders their formation difficult with conventional punch tooling. In such a manufacturing operation, custom tooling is required to make a two-stage cut in the cell. Additionally, the scrap material from the punched upper aperture is likely to be retained in the cell, having no sufficiently sized hole in the lower surface of the cell to drop through.  
         SUMMARY OF THE INVENTION  
         [0009]    A cell and method of manufacturing a cell for a multi-cell window covering is disclosed. The method begins with the step of providing a flexible material defined as an elongated member having axial and transverse directions. A portion of the flexible material is then stiffened to create at least one axially extending flexible junction. At least one control engagement formation and at least one control clearance formation are then created in axially extending sections of the stiffened flexible material that will become an upper portion and a lower portion of the cell. The flexible material is then folded to create a closed element and the flexible material is secured to itself to maintain the shape of the closed element.  
           [0010]    The method of the present invention enables the manufacture of expandable and collapsible cells for a window covering, using common raw materials. The proposed method uses relatively inexpensive tooling to produce cells having distinct features in the upper and lower surfaces of the cells. The ability to create distinct features in the top and bottom surfaces of the cells enables the use of cords that selectively engage either the upper or lower portions of the cells at predetermined locations.  
           [0011]    Various additional aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an exploded perspective view showing a portion of a window covering employing a plurality of cells manufactured according to the principles of the present invention;  
         [0013]    [0013]FIG. 2 is a side view of a window covering employing a plurality of cells manufactured according to the principles of the present invention, wherein a plurality of cells are arranged in an open (collapsed) position;  
         [0014]    [0014]FIG. 3 is a side view of the window covering of FIG. 2, wherein the cells are arranged in a closed (expanded) position;  
         [0015]    [0015]FIG. 4 is a cross-sectional view of a cord element and cord for use in expanding and collapsing the cells of a window covering;  
         [0016]    [0016]FIG. 5 is perspective view showing the cord element of FIG. 4 prior to engagement with an opening in a cell;  
         [0017]    [0017]FIG. 6 is a plan view of a laminate prior to folding the laminate into a cell;  
         [0018]    [0018]FIG. 7 is a side view of the laminate of FIG. 6 after folding the laminate into a cell; and  
         [0019]    [0019]FIG. 8 is a simplified perspective view of an exemplary manufacturing line for manufacturing the cells of FIGS. 6 and 7. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    Referring now to the drawings, the preferred embodiments of the present invention are described in detail. Referring to FIGS.  1 - 3 , an exemplary window covering  10  is shown within which an actuator device  12  is employed for controlling the light transmitting properties of window covering  10 . Window covering  10  preferably includes a plurality of elongated cells  14 , all of which are preferably arranged parallel to one another. Each cell  14  is adapted to be expanded and collapsed so as to provide variable light control and see-through capability for window covering  10 . FIG. 3 depicts cells  14  in the expanded position, wherein adjacent cells  14  are in contact with one another, while FIG. 2 depicts cells  14  in a partly collapsed position, wherein adjacent cells  14  are separated from one another. The design and configuration of window covering  10  is by way of example only and is not intended to limit the scope of the invention as claimed. Accordingly, the components of the exemplary window covering  10 , more particularly actuator device  12 , can be arranged and designed in a wide variety of different configurations.  
         [0021]    In order to achieve the collapsibility and expandability of cells  14 , a cooperating pair of cords, i.e., a first cord  16  and a second cord  18 , are employed in actuator device  12 . As illustrated in FIG. 1, it is contemplated that a plurality of cord pairs could be disposed along the length of cells  14 , the number of pairs employed generally depending on the width of window covering  10 . At their upper extreme, cords  16  and  18  are secured to an actuator mechanism that is housed in a head-rail  22 . In the embodiment illustrated in FIGS.  1 - 3 , the actuator mechanism is a rotatable member  20  that includes a pair of integrally formed arms  23  to which cords  16 ,  18  are attached, but is not intended to be limited thereto. As will be described in further detail below, rotatable member  20  can be rotated in a direction that causes first cord  16  to move upward and second cord  18  to simultaneously move downward, and vice versa.  
         [0022]    In order to adjust the shape of each cell  14 , first cord  16  is adapted to support the lower portion of each cell  14  and second cord  18  is adapted to support the upper portion of each cell  14 . By raising and lowering first cord  16  and second cord  18 , each cell  14  can be expanded (see FIG. 3) or collapsed (see FIG. 2), without substantially lifting or lowering the weight of cells  14 .  
         [0023]    To support the lower portion of each cell  14 , first cord  16  includes a plurality of elements  34  positioned along its length. Elements  34  are preferably spaced equally apart, such as in a bead chain, and each element  34  is adapted to abut an outer surface of the lower portion of a corresponding cell  14 . When first cord  16  is raised, each element  34  presses upwardly against and lifts the lower portion of its associated cell  14 . This lifting action results in the collapsing of each cell  14 , as illustrated in FIG. 2. Collapse of each cell  14  is further facilitated by the lowering of second cord  18  (as described below), which occurs simultaneously with the raising of first cord  16  due to the pivotal movement of rotatable member  20 . In the fully expanded condition of each cell  14  (as shown in FIG. 3), elements  34  drop through an enlarged aperture in the next lower cell, so as not to interfere with the desired face-to-face contact between adjacent cells  14  in the fully closed or view-blocking condition of cells  14 .  
         [0024]    Similarly, second cord  18  includes a plurality of elements  36  positioned along its length. Each element  36  serves the function of providing support to the upper portion of a corresponding cell  14 . As illustrated in FIGS. 4 and 5, elements  36  are preferably formed like small spools having a slot  38  that is slightly larger than the wall thickness of a mating cell  14 . The outer surfaces of elements  36  are preferably conical to facilitate entry into an opening  40  in cell  14 . The above-described structure of element  36  is not intended to be limited thereto, but may include other configurations such as clips, knots, loops and the like.  
         [0025]    Referring to FIG. 5, opening  40  includes a first portion  42  that is large enough for elements  36  to be inserted into, and a second smaller portion  43  separated from first portion  42  by a tapered channel  44 . Connecting elements  36  to cells  14  is accomplished by inserting element  36  into first portion  42  of opening  40  and subsequently sliding element  36  into second portion  43 . Although not required, connecting elements  36  with the upper portion of each cell  14  at portions  43  advantageously reduces the tendency of cells  14  to flutter when collapsed or nearly collapsed.  
         [0026]    Referring again to FIG. 2, each element  36  is used to support each cell  14  from the upper portion thereof. Therefore, when second cord  18  is raised along its longitudinal axis, each engaged element  36  supports each cell  14  from the upper portion thereof, wherein each cell  14  tends to “hang” from its engaged element  36 . By raising cord  18 , each cell  14  is suspended from its upper portion, while the simultaneous lowering of lift cord  16  and associated elements  34  allows the lower portion to move downwardly, thereby resulting in the expansion of cells  14 .  
         [0027]    Because the operative plane of cooperating cords  16  and  18  is substantially parallel with the plane of window covering  10 , the expansion of cells  14  is effected by the relative raising of hang cord  18  and lowering of first cord  16  without significant fore-and-aft rotation or tilting of any cell  14  (as opposed to the case of intended tilting in conventional venetian blinds). In achieving the collapsibility and expandability of cells  14 , it is essential that the ratio of the stiffness of each cell juncture to the weight of each cell  14  be selected so as to facilitate cell expandability and collapsibility. More specifically, the stiffness to weight ratio should be such that when the cells are supported from the upper portion, the weight of each cell  14  is sufficient to open the cell, and when cells  14  are supported from the lower portion, the stiffness of each cell juncture must be low enough so as to facilitate the collapsing of the cell. Accordingly, expansion of cells  14  is gravity-driven, requiring that second cord  18  regulate the expansion of cells  14 , not force it.  
         [0028]    As illustrated in FIG. 6, a single cell  14 , according to an embodiment of the present invention, is fabricated from a strip of a flexible material  46 , such as a woven fabric. In a first manufacturing step, flexible material  46  is stiffened, such as by applying a curable stiffening compound to flexible material  46 , or by laminating flexible material  46  with at least one stiffening member  48 , such as, for example, a narrow strip of plastic film, stiffened fabric or metal ribbon.  
         [0029]    In an exemplary embodiment of the present invention, flexible material  46  is laminated with at least two stiffening members  48 , each spaced a predetermined distance apart, to form a laminate  50 . Optionally, for aesthetic reasons, at least one of stiffening members  48  may be colored prior to laminating flexible material  46 . The colored stiffening member(s)  48  is secured to flexible material  46  in an area that will be visible from within a room where the window covering is extended. Because the flexible material  46  selected may be translucent, the colored stiffening member(s) is visible through the material, permitting cells  14  of the window covering to match the decor of the room.  
         [0030]    Preferably, for reasons that will be explained below, the stiffening members that help form the upper and lower portions of cells  14 , depicted as stiffening members  49  in FIG. 6, are a substantially rigid, yet formable material, such as metal. The gaps  52  provided between stiffening members  48 ,  49  permit flexible material  46  to act as a living hinge, allowing laminate  50  to be folded into a multisided tubular element  54 . A closure seal  56 , such as an adhesive or double sided tape, is provided between opposing edges  58 ,  60  of laminate  50  to retain tubular element  54  in tubular form. The joint between edges  58 ,  60  may be created as an overlapping joint, as illustrated in FIG. 7 or, alternatively, a butt-type joint (not shown).  
         [0031]    In the process of manufacturing tubular element  54 , it is desirable to maximize the longitudinal bending stiffness of laminate  50  to minimize the number of pairs of support cords  16 ,  18  needed to support cells  14  in window covering  10 . Referring to FIG. 8, to increase the bending stiffness of laminate  50 , stiffening members  49  are roll-formed or otherwise processed by a forming device  59  to give stiffening members  49  a curved, transverse cross-sectional shape (not illustrated). Forming the metal stiffening members  49  in this manner increases their effective section modulus, thereby increasing the longitudinal bending stiffness of laminate  50  as a whole. Alternatively, stiffening members  49  may be formed with a slight curve prior to laminating flexible material  46 , particularly when stiffening members  49  are made from materials other than metal.  
         [0032]    Prior to closing cell  14 , stiffening members  49  are punched with a series of openings  40  by a punching tool  61 . The spacing between openings  40  is generally a function of the bending stiffness of cells  14  and the relative vertical position of cords  16 ,  18 . Because the portions of laminate  50  that will later become aligned at each location in top and bottom arrangement are, at this step, side-by-side transverse to the length of laminate  50 , the punching operation can be accomplished simultaneously with one tool for both top and bottom openings  40 . Alternatively, openings  40  may be created in laminate  50  by slitting, stitching or otherwise forming an engagement feature in laminate  50  for receiving elements  34 ,  36  or allowing passage of cords  16 ,  18 . In addition, punching of adjacent openings  40  can also be achieved either simultaneously or in timed sequence with multiple punching tools, instead of the single punching tool described above.  
         [0033]    The punched laminate  50  is then moved over a series of guides  62  that fold laminate  50  along at least two predetermined hinge lines, bringing the upper and lower surfaces of laminate  50  into an over-and-under position, as shown in FIG. 8. Closure seal  56  is then adhered to opposite edges of laminate  50 , in an overlapping manner, to form the closed element  54 . The cross-sectional profile of closed element  54  and finished cells  14  are not limited to the profile shown in FIGS. 2 and 3. It will be appreciated that the method of the present invention may be used to manufacture cells having different cross-sectional profiles, including, but not limited to, the cells disclosed in U.S. Pat. No. 5,680,891 to Kendall Prince.  
         [0034]    Referring still to FIG. 8, each closed element  54  is then directed through a shearing machine  64 , which is continuously timed by a measurement of the position of laminate  50 , so as to be in register with the position of the punched openings  40 . The position of laminate  50  may be continuously determined, for example, by a conventional encoder on pulling rolls  66 , which act to pull laminate  50  through the manufacturing line, or by other means known in the art. This shearing operation generates a plurality of cells  14  with regularly spaced openings  40 , symmetrically located between the sheared ends of cells  14 . Cells  14  may then be strung together with cords  16  and  18 , as described above, and attached to the actuator mechanism in head-rail  22  to form window covering  10 . Alternatively, closed element  54  may be sheared into discrete cells before punching, such as by using a set of substantially identical punches on a self-spacing pantograph linkage (none illustrated), to provide for substantially equal spacing of the punches between sheared ends.  
         [0035]    The disclosed method enables the manufacture of expandable and collapsible cells for a window covering, using common raw materials. The proposed method uses relatively inexpensive and ordinary tooling to produce cells having distinct features in the upper and lower surfaces of the cells. The ability to create distinct features in the top and bottom surfaces of the cells enables the use of cords that selectively engage either the upper or lower portions of the cells at predetermined locations. Such selective engagement permits independent, but coordinated, control of the expansion and collapse of the cells in a cellular window covering.  
         [0036]    Although certain preferred embodiments of the present invention have been described, the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention. A person of ordinary skill in the art will realize that certain modifications and variations will come within the teachings of this invention and that such variations and modifications are within its spirit and the scope as defined by the claims.

Summary:
A cell and method of manufacturing a cell for a multi-cell window covering is disclosed. The method includes the steps of providing a flexible material, stiffening a portion of the flexible material, and creating at least one control engagement formation and at least one control clearance formation in axially extending sections of the stiffened flexible material that will become an upper portion and a lower portion of the cell. The method is further defined by folding the flexible material to create a closed element and securing the flexible material to itself to maintain the shape of the closed element.