FIELD OF THE INVENTION 
   The present invention relates to a slat, such as that typically found in horizontal (i.e., Venetian) or vertical blinds, which is constructed from a material that is thin and lightweight, yet strong enough to support both the weight of its own skeletal structures and a that of a decorative covering enclosing its skeletal structures to achieve a sophisticated window treatment which is sturdy, economical, functionally efficient, and aesthetically pleasing to a wide range of decorating tastes. 
   BACKGROUND OF THE INVENTION 
   Typically, where louvered window coverings, such as horizontal or vertical blinds, are used for decorative purposes and for controlling the transmission of light through a window, and especially where it is preferable to achieve a sophisticated aesthetic, the selection of affordable window coverings is severely limited. 
   It is most often the case that the higher-end louvered window treatments utilize thick, heavy slats which are constructed either from solid wood at least 3 mm thick or from an equally thick, equally dense and equally expensive composite manufactured to look and feel like genuine wood. However, using genuine wood slats can be prohibitively expensive because of the high costs of stain-grade wood, particularly in applications where multiple window treatments are necessary. Furthermore, costs can be compounded where windows are not a standard size and customization is required. Composite materials fashioned to look like genuine wood often present similar problems in terms of expense. Unfortunately, plantation shutters and other similarly rich-looking louvered alternatives are rarely a satisfactory substitute from an economic perspective because the grade and thickness of wood necessary to construct those kinds of window coverings still results in high manufacturing costs which must be passed along to the consumer. Of course, where an application requires vertical blinds, an owner currently has few if any alternatives to the more costly wood and synthetic wood-look blinds. 
   Another common problem with the use of conventional high-end louvered window coverings which utilize thick and heavy wood or wood-look slats is that a window treatment spanning even a standard or longer width window may begin to warp and sag over time, either because of the weight of materials typically used to manufacture the slats or because of the susceptibility of that material to changes in temperature and humidity. Windows that span an appreciable width may require a louvered window covering to be applied in several small sections rather than using a single window treatment which fully spans the width of the window, to avoid sagging and warping. Multiple narrow blind sets used to cover a single window result in a segmented look that is generally undesirable, but there are few alternatives currently available. One available alternative, albeit expensive, is plantation shutters. However, plantation shutters may not always be an option as it is often the case that they can only be used where the window to be treated has ample room for the shutters to be mounted inside the window frame. Even where outside-mount shutters are an option, the support structures between windows are often not wide enough or not substantial enough to support the hardware necessary to mount the shutters. Additionally, because the slats of plantation shutters covers only about 70% of the window (the other 30% of window coverage being attributable to the fixed frame portion of the shutters), the user generally has less control over light transmission than with traditional horizontal or vertical blinds. Finally, although the slats of plantation shutters are usually short enough so that warp and sag may not be issues, the cost of the shutters is still likely to be prohibitively high because large quantities of stain-grade wood are necessary for their manufacture. 
   Yet another difficulty facing those who desire quality window treatments is that, in homes or offices where construction may be less than optimal, i.e., where the walls may be constructed of an insubstantial material which is unsuitable for mounting a window treatment of any appreciable weight, the selection of available window treatments is further narrowed. There are very few, if any, window treatments currently available which are of a weight light enough to be installed in virtually any setting yet which still imply high quality and good taste. 
   Finally, manufacturing thick wooden slats for use in conventional louvered window coverings necessarily means consumption of large quantities of wood in the process. In addition to the associated economic costs, using large quantities of wood severely impacts the environment. The environmental effects are even greater where manufacturers may be using wood harvested from older hardwoods, which are extremely difficult if not impossible to renew. Moreover, the high grade of wood required for use in high-end blind systems results in a large volume of waste product attributable to slats that do not make the grade, thus creating more environmental waste as well as generating an additional manufacturing expense that will be passed to the consumer in the price of the window coverings. 
   What is therefore needed is a slat that is affordable, versatile, and functional, yet which is aesthetically pleasing to even the most discriminating user. The ideal slat will be incorporable into almost all horizontal or vertical louvered blind systems, and will have support structures optimally constructed from materials which may be as thin as 1.5 mm but which are strong enough to provide rigid support for a variety of decorative coverings. As a result, the ideal slat will be lightweight, relatively inexpensive, universally useable, and environmentally conservative. 
   SUMMARY OF THE INVENTION 
   The present invention involves both the structures and process for producing covered slats for use in a louvered window covering. The covered slats of the present invention have a skeletal structure which is optimally constructed from materials which are lightweight yet strong enough to support both the skeletal structure itself and any one of a variety of decorative coverings to achieve a sophisticated aesthetic at an affordable cost. The skeletal structure is ideally constructed from a material, such as wood or plastic, manufactured to a thickness which is much less thick (as thin as 1.5 mm), and thus much more lightweight, than the thickness of material used in conventionally available slats (as thick as 3 mm or more), but which retains sufficient rigidity to provide the strength of support necessary to avoid warping or sagging. A wide range of materials, such as vinyl, plastic, or fabric, may be used to cover the skeletal structure, creating an infinite range of decorating possibilities. Furthermore, the covering can be of a material susceptible to the application of embellishments, such as machine-generated artwork, hand-applied artwork, edge-gilding, or trim, further expanding the numerous ways in which the look of the slats can be varied. Once the covering is fitted around the skeletal structure, the edges of the covering may be closed together using any of a variety of different techniques. For example, if the covering is sensitive to heat and/or pressure, such as vinyl or plastic would be, the edges can be crimped or welded together. Otherwise, the edges of the covering can be sewn, glued, or bonded together ultrasonically. Finally, to increase the probability that the edges will stay bonded together over time and variations in temperature, humidity, and ultra-violet exposure, multiple combinations of the aforementioned techniques (for example, sewing in addition to gluing or welding) may be used to close the edges of the covering once it is fitted around the skeletal structure of the slat. Incorporation of the covered slats of the present invention in a louvered window covering will result in a sophisticated window covering which is aesthetically desirable, yet is environmentally conservative, is more economical in terms of both materials and cost, is lighter in weight, and is more universally useable than conventional louvered window coverings. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a perspective view of a first embodiment of the covered slat of the present invention and includes cutaway views revealing a skeletal slat between two layers of covering which are sealed and sewn together along four edges, and  FIG. 1  further illustrates two elongate apertures extending through both layers of covering and through the skeletal slat to accommodate a string, rope, or ladder system such as that used to raise, lower, or adjust a set of blinds; 
       FIG. 2  is a cross-sectional perspective view taken along line  2 - 2  of  FIG. 1  which illustrates in greater detail the placement of the skeletal slat between two layers of covering which are sealed and sewn together; 
       FIG. 3  is a view of one end of the covered slat shown in  FIG. 1  and illustrates the application of gold-leaf embellishment on the surface of the covering along its outer edges; 
       FIG. 4  is perspective view of the first embodiment of the covered slat of the present invention illustrating a different technique used for covering the skeletal slat, and includes cutaway views revealing the placement of the skeletal slat inside a single layer of covering which is folded over the skeletal slat along its length and which is sewn together along three sides, and  FIG. 4  further illustrates a pair of notches in the covering on each side of the covered slat to accommodate a string, rope, or ladder system such as those used to raise, lower, and adjust blinds in certain blind systems; 
       FIG. 5  is a cross-sectional perspective view along line  4 - 4  of  FIG. 3  which illustrates in greater detail the skeletal slat of  FIG. 3  enclosed within a single layer of covering having sewn edges; 
       FIG. 6  is a perspective view of the top of a second embodiment of the covered slat of the present invention and includes a cross-sectional view of one end of the covered slat which reveals a skeletal slat and 2 cylindrical rods extending along the top outer edges of the skeletal slat, all of which are between two layers of covering sewn together on four sides such that the ribs and adjacent portions of the skeletal slat are compartmentalized; 
       FIG. 7  is a perspective view of the bottom of the second embodiment of the covered slat of the present invention and further illustrates two elongate apertures extending through both layers of covering and through the skeletal slat to accommodate a string system such as that used in a louver type blind system; 
       FIG. 8  is an exploded cross-sectional view of the second embodiment of the covered slat taken along line  8 - 8  of  FIG. 7  which more clearly illustrates the skeletal slat and the two rods sewn between two layers of covering; and, 
       FIG. 9  is an exploded cross-sectional view of a third embodiment of the covered slat of the present invention which illustrates a flanged skeletal slat sewn between two layers of covering. 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The description of the covered slat of the present invention is best described with reference first to  FIG. 1 , which illustrates a first embodiment of the covered slat  21  of the present invention. Covered slat  21  comprises a skeletal structure hereinafter a skeletal slat  23 , a portion of its first main surface being seen, and with its second main surface opposite the first main surface not seen in  FIG. 1 . Skeletal slat  23  has a first end  25 , a second end  27  oppositely disposed from first end  25 , a first side surface seen as a first side  29 , and a side surface seen as a second side  31  oppositely disposed from first side  29 . The skeletal slat  23  may be made of wood, fiber, graphite, polypropylene, composite, bamboo, epoxy, fiberglass, metal, polystyrene, and nylon to name a few. The skeletal slat  23  is enclosed by a first layer of covering  33  and a second layer of covering  35 . First layer of covering  33  is illustrated as optionally having texturing  37 , and both layers of covering  33  and  35  are slightly larger in area than skeletal slat  23  so that sufficient overlap exits on all four sides of skeletal slat  23  for attaching the first layer of covering  33  to the second layer of covering  35  to enclose the skeletal slat  23 . The covered slat  21  of  FIG. 1  is illustrated as having raw edges  39 . Sufficient overlap, areas where both layers of covering  33  and  35  oppose each other beyond the extent of the skeletal slat  23 , usually approximates 3 mm-5 mm for raw edges such as those in  FIG. 1  and approximately 6 mm-10 mm for finished edges (see description of  FIG. 4 ). 
   The two layers of covering  33  and  35  may be sealed together as shown in  FIG. 2  to form a seam  41  adjacent first and second ends  25  and  27  and first and second sides  29  and  31  of skeletal slat  23 . The two layers of covering  33  and  35  may be additionally sewn together with stitching  43  along the inside edge of seam  41 . The covering can be joined together using any number of different techniques. For example, where the covering material is susceptible to heat and pressure, the edges can be heat sealed or welded together as illustrated in  FIG. 1 . Additionally, the two layers of covering  33  and  35  may be sewn, glued, or ultrasonically bonded together. 
   The aforementioned techniques can also be used in combination with one another to ensure that the covering remains securely in place around the skeletal structures. For instance, where glue is used to seal the coverings together, sewn reinforcement of the coverings may be helpful in preventing separation of the layers if the glue should dry out and become ineffective because of age, temperature changes, exposure to ultra-violet light, or fluctuations in humidity. Even where the coverings are sealed together with a more reliable technique such as heat sealing, it may still be desirable to use stitching to reinforce the seams (as in  FIG. 1 ) in case any segment of the seam fails to seal. 
     FIG. 1  further illustrates a pair of elongate apertures  45  which partially transverse the width of the covered slat  21  (the width being generally equivalent to the distance between first side  29  and second side  31  of skeletal slat  23 ) and which extend through the first layer of covering  33 , the skeletal slat  23 , and the second layer of covering  35  to accommodate a rope or string lift cord such as that commonly used in louvered blind systems to raise and lower the slats and to adjust the angle of the slats to control light transmission. Note that the apertures  45  can be made smaller depending on the diameter of the string or rope to be passed through them. The apertures  45  are ideally created during the process of manufacturing but may be added after-market as well. 
     FIG. 2  is a cross-sectional perspective end view along line  2 - 2  of  FIG. 1  which illustrates the covered slat  21  including the skeletal slat  23  between the two layers of covering  33  and  35 , the seam  41  and the stitching  43 .  FIG. 2  more clearly illustrates the thickness T 1  of the skeletal slat  23 . Optimally, the skeletal slat  23  will be constructed of a material, such as wood, fiber, or plastic, manufactured to a thickness T 1  which just allows the skeletal slat to support itself and a given covering without sagging or bending. For wood slats, the optimal thickness T 1  in terms of cost and rigidity will be approximately 1.5 mm, but may vary slightly depending on the weight of the coverings  33  and  35  used to enclose the skeletal slat  23 . 
     FIG. 3  is a view of one end of the covered slat  21  shown in  FIG. 1  and further illustrates the application of gold-leaf  47 , or any other metallic or thin material, being applied to the first layer of covering  33  along or adjacent seam  41 . The coverings used to enclose the skeletal structure of any embodiment of the covered slat of the present invention can be further enhanced during the manufacturing process by this or any number of other different embellishments to vary their appearance, such as machine-applied or hand-applied artwork or trim, thus creating an infinite number of decorating possibilities. 
     FIG. 4  is perspective view of the first embodiment of the covered slat  21  of the present invention which is covered using a slightly different technique than that illustrated in  FIGS. 1-3 .  FIG. 4  includes cutaway views which reveal the skeletal slat  23  inside a single layer of covering  49  with texturing  51  which is folded over the skeletal slat  23  to form a radius  53  adjacent the first side  29  of the skeletal slat  23 . The covering  49  is sewn together with stitching  55  adjacent the first and second ends  25  and  27  and adjacent the second side  31  of skeletal slat  23 . Note that when the covering  49  is sewn together using stitching  55 , the covering edges  57  distal to stitching  55  may be raw as in  FIG. 3  or may be given a more finished look by making a fold in the raw covering edges  57  prior to sewing such that the raw covering edges  57  are turned inward and caught in the stitching  55  leaving turned edges for a more cleanly upholstered look.  FIG. 3  also illustrates a first pair of notches  59  carved into covering  49  adjacent the first side  29  of covered slat  21  and a second pair of notches  61  carved into covering  49  on the second side  31  of covered slat  21  to accommodate a vertical set of strings in a ladder cord which supports such as those commonly used to raise, lower, and adjust the slats in louver-type blind systems. 
     FIG. 5  is a cross-sectional perspective view along line  5 - 5  of  FIG. 4  which illustrates the skeletal slat  23  enclosed within the single layer of covering  49  and illustrates in greater detail the skeletal slat  23 , radius  53  formed by covering  49  adjacent the first side  29  of skeletal slat  23  and stitching  55  adjacent the second side  31  of skeletal slat  23 . As in  FIG. 2 ,  FIG. 4  clearly illustrates the thickness T 1  of skeletal slat  23 , which, again, may optimally be around 1.5 mm but which may vary slightly depending on the weight of the covering  49  used to enclose the skeletal slat  23 . 
     FIG. 6  is a cross-sectional perspective view of the top of a further embodiment of the covered slat  63  of the present invention.  FIG. 6  illustrates a skeletal slat  65  having a narrow first side  69 , a narrow second side  71  oppositely disposed from first side  69 , and a top surface  73 .  FIG. 6  further illustrates a first rod  75  extending along the top surface  73  of the skeletal slat  65  adjacent and parallel to first side  69  of the skeletal slat  65  and a second rod  77  extending along the top surface  73  of the skeletal slat  65  adjacent and parallel to second side  71  of the skeletal slat  65 . First and second rods  75  and  77  may preferably constructed of hard plastic in a diameter which is optimally between 2 mm and 2.5 mm for maximum rigidity and weight-bearing capacity as well as minimal breakability and weight. Although first and second rods  75  and  77  are illustrated in  FIG. 6  as having a circular cross-sectional shape, they can conceivably be manufactured in a variety of other cross-sectional shapes such as square or triangular. The skeletal slat  65  and rods  75  and  77  are between a top layer of covering  79  and a bottom layer of covering  81 . In  FIG. 6 , the layers of covering  79  and  81  are sewn together with stitching  83  which runs parallel to rods  75  and  77  and which is adjacent each of rods  75  and  77  both medially and laterally. The stitching  83  which is situated medial to rods  75  and  77  extends through skeletal slat  65  so that both rods  75  and  77  are compartmentalized, thus stabilizing the skeletal structures of the covered slat  63  for maximum rigidity and support. The configuration of rods  75  and  77  creates a pair of ridges  85  in the top layer of covering  79  which are approximately the similar in height as the diameter of rods  75  and  77  (2 mm to 2.5 mm). Extending between the pair of ridges  85  is a planar surface  87  formed by the top layer of covering  79  which is in approximately the same plane as top surface  73  of skeletal slat  65 . 
     FIG. 7  is a perspective view of the bottom of the second embodiment of the covered slat  63  of the present invention which illustrates the covered slat  63  as having a pair of elongate apertures  89  which partially extend over the width of the covered slat  63  (the width being generally equivalent to the distance between first side  69  and second side  71  of skeletal slat  65 ) and which extend through the top layer of covering  79 , the skeletal slat  65  (not illustrated in  FIG. 7 ), and the bottom layer of covering  81  to accommodate a rope or string such as a lift cord that commonly used in louvered blind systems to raise and lower the slats and to adjust the angle of the slats to control light transmission. Note that the pair of apertures  89  can be made significantly smaller depending on the diameter of string or rope to be passed through them. The pair of apertures  89  are ideally created during the process of manufacturing but may be added after-market as well. In  FIG. 7 , the layers of covering  79  and  81  are illustrated as sealed together adjacent both ends of skeletal slat  65 , forming a seam  91 , though the coverings  79  and  81  could conceivably be sewn together as well, either in addition to or instead of being sealed. Bottom covering  81  is illustrated in  FIG. 7  having texturing  93 , but can conceivably be any of an infinite variety of coverings which may or may not be textured. The four rows of stitching  83  are shown as compartmentalizing rods  75  and  77  on the top of the skeletal slat  65  are anchored in the bottom covering  81  as illustrated in  FIG. 7 . 
     FIG. 8  is an exploded cross-sectional view of the second embodiment of the covered slat  63  taken along line  8 - 8  of  FIG. 7 .  FIG. 8  more clearly illustrates skeletal slat  65  and rods  75  and  77 , all of which are sewn and sealed between the two layers of covering  79  and  81  as described in  FIG. 7 . The rigidity necessary to support the structures of this embodiment derives mostly from rods  75  and  77 ; consequently, thickness T 2  of the skeletal slat  65  will optimally be between 0.5 mm and 1 mm, somewhat thinner than its wood counterpart since the primary function of the skeletal slat  65  in this embodiment may be to impart shape more than support. 
     FIG. 9  is an exploded view of a third embodiment of the covered slat  95  of the present invention having a first side  97  and a second side  99  oppositely disposed from first side  97 . Covered slat  95  comprises an extruded I-shaped skeletal slat  101  having a planar middle portion  103  which extends between a first rib member  105  and a second rib member  107 . Skeletal slat  101  is illustrated between a first layer of covering  109  and a second layer of covering  111 . First and second rib members  105  and  107  protrude away from the plane of middle portion  103  on both sides of covered slat  95  such that first rib member  105  forms a first ridge  113  in the first layer of covering  109  and a second ridge  115  in the second layer of covering  111 , and second rib member  107  forms a first ridge  117  in the first layer of covering  109  and a second ridge  119  in the second layer of covering  111 . Layers of covering  109  and  111  are sewn together with stitching  121  which runs parallel to first and second rib members  105  and  107  and which is adjacent rib members  105  and  107  both medially and laterally. The stitching  121  which is medial to rib members  105  and  107  extends through the middle portion  103  of skeletal slat  101  so that both rib members  105  and  107  are compartmentalized. Rib members  105  and  107  should be approximately the same thickness as rods  75  and  77  in the covered slat  63  of  FIGS. 6 through 8 , i.e., 2 mm to 2.5 mm, in order to provide rigid support sufficient to avoid warping or bending. Similarly, the thickness T 3  of the skeletal slat  101  will be between 2 mm and 2.5 mm, slightly thicker than the skeletal slat  65  of the second embodiment of covered slat  63  described in  FIGS. 6 through 8 . Although rib members  105  and  107  are illustrated in  FIG. 9  as being generally rectangular in shape, rib members  105  and  107  can conceivably be any of a number of different shapes, such as spherical or triangular. 
   Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.
A finished slat for a window covering includes both the structures and process for producing covered slats. A skeletal structure optimally constructed from a material such as wood or plastic, manufactured to a thickness which is much less than that of conventional slats, yet which is strong enough to support both the skeletal structure and a decorative covering and is rigid enough to avoid warping or sagging over time. The decorative covering may be made from a wide variety of materials, thus creating an infinite range of decorating possibilities; further, the covering may be embellished with artwork or trim according to the tastes of the user. The covering may be closed together around the skeletal structure using any of a variety of techniques, such as heat welding, glue, ultrasonic bonding, stitching, or any combination thereof.