Abstract:
A swimming pool cover with lenses is disclosed. The swimming pool cover uses lenses to focus ambient solar energy into the water of a swimming pool. In one embodiment, a plurality of rectangular lenses is connected at their edges by a minimal amount of connecting or gusset material, in order to create an impermeable sheet, while maximizing the amount of incident solar energy absorbed by the swimming pool water. The swimming pool cover also protects detritus from falling into the swimming pool, while at the same time, reduces the amount of heat loss through evaporation. In another embodiment, the gusset material connects a plurality of lenses, varying in both size and shape.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 62/278,131, filed Jan. 13, 2016, the contents of which are incorporated by reference herein in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    In general, the invention relates to swimming pool covers. 
         [0004]    2. Description of Related Art 
         [0005]    According to industry sources, there were 8.6 million residential swimming pools and 309,000 public swimming pools in the United States in 2013. In many areas, swimming pools are an indelible feature of the suburban landscape and a quintessential part of suburban recreation, in addition to their prominent role in exercise and athletic competition. 
         [0006]    Most residential swimming pools are outdoors and are either in-ground or above ground. Particularly in warm climates, where an outdoor swimming pool can be used year round, the pool may be surrounded by a screened enclosure, which prevents leaves and other detritus from falling into the pool. However, screened enclosures can present considerable cost and maintenance issues, and are far from universal. 
         [0007]    Where a screened enclosure is not available, or where the local climate is too cold for year-round swimming, swimming pools are often covered when they are not in use. Various types of swimming pool covers are available. At its most basic, a swimming pool cover may be little more than a sheet of plastic, typically vinyl. More complex versions may have insulation. Of course, not all swimming pool covers are in sheet form—U.S. Pat. No. 4,270,232 to Ballew, for example, discloses a cover made of discrete segments that float next to one another on the surface of the water. At least portions of those segments are transparent and transmit heat. 
         [0008]    Most outdoor swimming pools are not automatically heated or cooled; the temperature of the water is thus dependent on the environment and the weather. However, the temperature of a swimming pool&#39;s water is a major factor in having a comfortable and productive swimming experience. While a basic swimming pool cover allows some amount of solar energy to be absorbed by the swimming pool water, the basic swimming pool cover only allows the pool water to absorb a fraction of the available energy. In fact, most basic swimming pool covers actually provide shade over a swimming pool, much like an umbrella, and actually reduce the amount of solar energy absorbed by the swimming pool water. 
       SUMMARY OF THE INVENTION 
       [0009]    One aspect of the invention relates to a swimming pool cover comprised of a plurality of lenses. The swimming pool cover uses this plurality of lenses to focus ambient solar energy, and may result in heating of the pool water. A connecting or gusset material joins the edges of the plurality of lenses into a sheet that covers at least substantial majority of the swimming pool. In many embodiments, the swimming pool cover may be sized and shaped to cover the entire pool. In one embodiment, the lenses themselves are thin, flexible Fresnel lenses. In an additional embodiment, the individual lenses themselves are replaceable, being connected by a fastener system such as VELCRO® hook-and-loop fastener. The swimming pool cover performs other functions as well—it protects a swimming pool from detritus falling into the pool, and may also substantially reduce water loss due to evaporation. 
         [0010]    Other aspects, features and advantages of the invention will be set forth in the description that follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0011]    The invention will be described with respect to the following drawing figures, in which like numerals represent like features throughout the figures, and in which: 
           [0012]      FIG. 1  is a perspective view of an swimming pool with a swimming pool cover according to one embodiment of the invention; 
           [0013]      FIG. 2  is a top plan view of a portion of the swimming pool cover of  FIG. 1 , showing a detailed view of one lens; 
           [0014]      FIG. 3  is a partially sectional perspective view of the swimming pool cover of  FIG. 1  illustrating the effect of the lenses; and 
           [0015]      FIG. 4  is a view similar to  FIG. 3  of the swimming pool cover of  FIG. 1  partially retracted and stored. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]      FIG. 1  is a perspective view of a swimming pool, generally indicated at  10 . The swimming pool  10  is protected from various outdoor elements with a swimming pool cover  12 , according to one embodiment of the invention. The swimming pool  10  could be either in-ground or above-ground. The swimming pool  10  of  FIG. 1  has a shallow end  22  and a deep end  24  with a gradual pitch  42  connecting the two ends of the swimming pool. A pool wall  34  surrounds the depth of the swimming pool  10 . The lower extent of the pool wall  34  is connected to the pool floor  36 . The upper extent of the pool wall  34  flares out into a swimming pool perimeter  38 . In an in-ground pool, the above-described features would typically be constructed from poured concrete, or a similar material. In an above-ground pool, the above-described features would typically be constructed of metal, FIBERGLAS™ glass fiber composite material, or other common materials. 
         [0017]    While the swimming pool  10  of the illustrated embodiment is generally rectangular, the pool cover  12  could be made in any shape or size, and could be installed on any type of swimming pool. Not all swimming pools need have all the features described above with respect to the swimming pool  10 ; for example, the pool cover  12  could be used with an infinity pool, i.e., a swimming pool with a reduced or angled border that appears to merge into the ocean or other surrounding landscape. 
         [0018]    The swimming pool cover  12  comprises a matrix of lenses  14  connected at their edges  16  by a connecting or gusset material  18 . The matrix of lenses  14  forms a sheet between the perimeter  38  of the pool  10 . In the illustrated embodiment, the lenses  14  are rectangular and the swimming pool cover  12  is essentially a rectangular grid of the lenses  14 . However, any shape or size of lens  14  would be appropriate, so long as the lenses  14  cover a substantial portion of the area of the swimming pool cover  12 . In many cases, the lenses  14  will comprise at least the majority of the surface area of the swimming pool cover  12 . 
         [0019]    While the lenses  14  of the illustrated embodiment are all the same size and shape, the sizes and shapes of the lenses  14  could also vary over the extent of the swimming pool cover, for either decorative or practical reasons. It may, for example, be desirable to have some round, triangular, or polygonally-shaped lenses for decorative reasons. Lenses  14  may have different shapes in the same swimming pool cover  12  for functional reasons as well. For example, if the swimming pool  10  is not rectangular, it may be advantageous to make lenses  14  of different shapes, so that the swimming pool cover  12  as a whole is shaped to cover the entire surface area of the pool water. 
         [0020]    The amount of connecting material  18  used between each lens edge  16  generally depends upon the shape and size of the pool  10 , as well as the shape and size of the lenses  14  that are used. In most embodiments, it will be advantageous to keep the amount of connecting material  18  between lenses to a minimum. Where connecting material  18  cannot be minimized, it may be translucent, transparent, or otherwise at least somewhat energy-transmissive. 
         [0021]      FIG. 2  is a top plan view of a portion of the pool cover  12  of  FIG. 1 , showing the lenses  14  in greater detail. The edges  16  of adjacent lenses  14  are connected by connecting material  18  in order to create a continuous swimming pool cover  12  that, in nearly all cases will be impermeable to water. The connecting or gusset material  18  could be connected to the lens  14  by any number of methods, including adhesives, stitching, fusing, fasteners, or combinations of those methods. In one embodiment, the lenses  14  themselves are replaceable, and are connected to the connecting material  18  with a fastener system, such as VELCRO® hook-and-loop fastener, or by any other suitable fastening system. Thus, if an individual lens  14  becomes soiled, scratched, or damaged by heat or ultraviolet radiation, it can be removed and replaced. 
         [0022]    The continuous, impermeable swimming pool cover  14  protects the areas of the swimming pool  10  it covers from collecting detritus and from exposure to wind. An additional benefit to making the swimming pool cover  12  continuously impermeable is that the swimming pool cover  12  may reduce the amount of water that evaporates from the swimming pool  10 . While  FIGS. 1 and 2  illustrate the swimming pool cover  12  covering the entirety of the swimming pool  10 , that need not be the case in all embodiments. In some cases, a swimming pool cover  12  can be used to cover only a portion of the swimming pool  10  while other portions remain open for use. 
         [0023]    In this embodiment of the invention, the lenses  14  are spaced together as closely as possible, so that most of the surface area of the swimming pool cover  12  is comprised of lenses. As was described briefly above, the arrangement of the plurality of lenses  14  can take any form so long as the lenses  14  form a continuous, closely packed pattern over the extent of the pool  10 . Additional connective material  18  could be used to accommodate irregular shapes or fill any void spaces that would otherwise compromise the impermeability of the pool cover  12 . 
         [0024]    As may be apparent in  FIG. 2 , the lenses  14  of the illustrated embodiment are Fresnel lenses  14 . Fresnel lenses  14  have many advantages, one of them being that Fresnel lenses are typically flatter than condensing lenses of comparable focal length. While Fresnel lenses  14  in embodiments of the invention may be made in any number of materials that have refractive indices different than that of air, it is advantageous if the material of which the Fresnel lenses  14  are made is thin and flexible, much as a conventional swimming pool cover would be. Moreover, thin, flexible Fresnel lenses that cover a relatively large area (e.g., 8.3″×11.75″) are readily available as reading magnifiers from vendors such as Amazon.com, Inc. Of course, the lenses  14  may be of substantially any size. Although any light-transmissive material with a refractive index different than that of air may have some refractive effect on light, the term “lens,” as used in this description, refers to an element with at least one curved surface that is intended to focus light. 
         [0025]      FIG. 3  is a partially sectional perspective view of the pool cover  12  of  FIG. 1 , illustrating the pool cover  12  with its matrix of lenses  14 . Generally speaking, the transparency of the lenses  14  will allow more light to pass through the pool water. The focusing effect of the lenses  14  may also result in more incident solar energy being directed into the pool water or less energy escaping the pool water. 
         [0026]    The amount of incident solar energy  30  is expected to vary with the season, as well as the progression of the sun throughout the day. Because they are particularly good at focusing off-axis beams of light, Fresnel lenses  14  may be particularly well suited to gather any available solar energy  30  and transfer some amount of that energy to the swimming pool water  28 . 
         [0027]    During the evening, when solar energy  30  is not available, the pool cover  12  may trap heat and prevent some amount of heat loss from the surface  28  of the swimming pool  10 . More particularly, the swimming pool cover  12  acts as an insulator against the reduced ambient temperatures of night. 
         [0028]      FIG. 4  is a partially sectional perspective view of the swimming pool cover  12 , similar to the view of  FIG. 3 , illustrating the pool cover  12  being retracted and stored in a storage container  40 . The retraction mechanism (not shown specifically in  FIG. 4 ) may be either manual or automatic. When the swimming pool  10  is in use, the swimming pool cover  12  may be stored by being wound in a circular fashion or folded in an accordion or bellows pattern. The method by which the swimming pool cover is gathered and stored may depend upon the size and shape of the lenses  14  used in the cover. One advantage of using thin, flexible lenses is that the resulting swimming pool cover  12  may be able to be retracted and wound or folded by a conventional automatic or manual mechanism, without requiring extensive modifications. 
         [0029]    While the invention has been described with respect to certain embodiments, the description is intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention, which is defined by the claims.