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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       FEDERALLY SPONSORED RESEARCH 
       [0002]    None. 
       SEQUENCE LISTING 
       [0003]    None. 
       BACKGROUND 
       [0004]    This invention relates to a hard or rigid swimming pool cover, as opposed to a rigid frame with flexible skin type of cover. The hard swimming pool cover raises and lowers automatically. The hard swimming pool cover can be used with in-ground or above-ground swimming pools. The aforementioned cover can be integral to the swimming pool frame or added as a separate retrofit mechanism to be installed with an existing in-ground or above-ground swimming pool. 
         [0005]    The aforementioned swimming pool cover prevents children, animals, unwanted guests, pollutant rain and debris such as dust and leaves from entering the pool when the cover is in the lowered or closed position. The cover cannot be raised or opened unless the operator has the key, passcode, etc. to turn on the mechanism that raises and lowers the cover. 
         [0006]    The convex dome, flat pitched or multi-faceted pitched from center hard cover shapes or designs that utilize rigid transparent plastic or glass materials refract the sunlight that penetrates the hard cover surface. The refracted sunlight is then concentrated onto the surface of the pool water. The combination of refracted sunlight and encapsulating the pool water with the hard pool cover makes the hard pool cover advantageous to warming the swimming pool water. Rigid plastic or glass materials with UV filters or photochromic rigid transparent plastic or glass materials can be used with the hard pool cover to reflect the sunlight that would hit the swimming pool water, in regions where it is not desired to heat the pool water because the outdoor air temperatures are so great that the pool water becomes too hot. 
         [0007]    U.S. Pat. No. 3,566,420 to Peterson (1971) claims the swimming pool cover to provide shade to the swimming pool when in the raised position. Typically swimmers enjoy the sun to warm the water and themselves. This invention allows for the option of allowing sunlight to pass through the rigid transparent material if desired. And block sunlight if it is not desired, through the use of rigid plastic or glass materials with UV filters or photochromic rigid transparent plastic or glass materials. 
         [0008]    Solar covers are the most widely used cover during seasons of active swimming pool use. Solar covers that are removed and reapplied to the swimming pool manually are time consuming and strenuous to remove before each use of the pool, and then reapply after each use of the pool. The hard cover relieves this time consuming and strenuous activity by the use of mechanism(s) that remove or raise the hard cover and reapply or lower the hard cover onto the pool. 
         [0009]    Swimming pool covers that are typically used during seasons of inactivity are often referred to as “winter covers”, these soft flexible covers consist mainly of tarpaulins, and some other type of soft vinyl covers. These covers again are typically always manually applied at the beginning of the season of inactivity and then removed at the end of the season of inactivity. The hard cover relieves the time consuming and strenuous activity of applying and removing the winter cover by the use of mechanism(s) that remove or raise the hard cover and reapply or lower the hard cover onto the pool. 
         [0010]    Alternatively, in regions where the hard pool cover that utilizes rigid plastic or glass materials with UV filters or photochromic rigid transparent plastic or glass materials is not needed, an opaque tarpaulin cover can be placed over top of the hard cover during seasons of inactivity so that light cannot penetrate through the transparent hard cover. The reason for this seasonal opaque tarpaulin cover is to prevent the swimming pool water from exposure to light which causes algae to grow. 
         [0011]    This patent is specific to an above-ground swimming pool with integral automatic raising and lowering hard cover, and an automatic raising and lowering retrofit hard cover for an existing in-ground and above-ground swimming pool. This patent is not intended to cover spas, hot tubs or swim spas as referenced in U.S. Pat. No. 6,718,566 to Wilson (2004) and U.S. Pat. No. 7,614,093 to Piche &amp; Bussiere (2009), which are specific to a spa or hot tub. 
       SUMMARY 
       [0012]    The aforementioned hard swimming pool cover provides:
       Safety to those that cannot swim.   Prohibiting access for unwanted guests.   A barrier that protects the pool water from pollutant rain and debris such as dust and leaves.   Ability to keep the pool water either warmer or cooler than would be without hard pool cover.   Easier removal and reapplication than that of solar covers, soft covers and winter covers used manually.       
 
     
    
     
       DRAWINGS 
         [0018]      FIG. 1  is a perspective view of an above-ground swimming pool with integral automatic raising and lowering hard cover constructed in accordance with the invention, showing the hard cover in the raised position. 
           [0019]      FIG. 2  is a perspective view of an above-ground swimming pool with integral automatic raising and lowering hard cover constructed in accordance with the invention, showing the hard cover in the lowered position. 
           [0020]      FIG. 3  is a perspective view of an above-ground swimming pool with retrofit automatic raising and lowering hard cover constructed in accordance with the invention, showing the hard cover in the raised position. 
           [0021]      FIG. 4  is a perspective view of an above-ground swimming pool with retrofit automatic raising and lowering hard cover constructed in accordance with the invention, showing the hard cover in the lowered position. 
           [0022]      FIG. 5  is a perspective view of an in-ground swimming pool with automatic raising and lowering retrofit hard cover constructed in accordance with the invention, showing the retrofit hard cover in the raised position. 
           [0023]      FIG. 6  is a perspective view of an in-ground swimming pool with automatic raising and lowering retrofit hard cover constructed in accordance with the invention, showing the retrofit hard cover in the lowered position. 
           [0024]      FIG. 7  is a top view of the convex dome shape hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0025]      FIG. 8  is a front view of the convex dome shape hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0026]      FIG. 9  is a top view of a multi-faceted pitched from center shaped hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0027]      FIG. 10  is a front view of a multi-faceted pitched from center shaped hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0028]      FIG. 11  is a perspective view of a multi-faceted pitched from center shaped hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0029]      FIG. 12  is a top view of a flat pitched shaped hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0030]      FIG. 13  is a side view of a flat pitched shaped hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0031]      FIG. 14  is a perspective view of a flat pitched shaped hard cover of  FIGS. 1,2,3,4,5 and 6 . 
           [0032]      FIG. 15  is a cross section view of the vertical support with integral actuator base/housing  16  of  FIGS. 1 and 2   
           [0033]      FIGS. 16, 17, 18 and 19  are top views of the shapes that apply to the above-ground swimming pool  10  shown in ( FIGS. 1 and 2 ), the existing above-ground swimming pool  22  shown in ( FIGS. 3 and 4 ) and also the existing in-ground swimming pool  25  shown in ( FIGS. 5 and 6 ). 
       
    
    
     DETAILED DESCRIPTION 
       [0034]      FIG. 1  is a perspective view taken of the above-ground swimming pool  10  with integral automatic raising and lowering hard cover  11  constructed in accordance with one embodiment. The hard cover  11  is raised off of the above-ground swimming pool  10  because the linear actuators  12  were commanded by the linear actuator power source/controller  20  to extend upwards. The upward extension of the linear actuators  12  manifests as a result of the actuator tubular compression members  15  moving up in relation to the bottom of the vertical support with integral actuator bases/housings  16 , until the actuator tubular compression members  15  obtain their pre-determined height. 
         [0035]      FIG. 2  is a perspective view taken of the above-ground swimming pool  10  with integral automatic raising and lowering hard cover  11  in the lowered position. The linear actuators  12  shown in ( FIG. 1 ) were not commanded by the linear actuator power source/controller  20  shown in ( FIG. 1 ) to extend upwards. Therefore the hard cover  11  remains in its lowered position on top of above-ground swimming pool  10 . 
         [0036]      FIG. 3  is a perspective view taken of the existing above-ground swimming pool  22  with automatic raising and lowering retrofit hard cover  24 . The retrofit hard cover  24  is raised off of the existing above-ground swimming pool  22  because the linear actuators  12  were commanded by the linear actuator power source/controller  20  to extend upwards. The upward extension of the linear actuators  12  manifests as a result of the actuator tubular compression members  15  moving up in relation to the bottom of the actuator bases/housings  23 , until the actuator tubular compression members  15  obtain their pre-determined height. 
         [0037]      FIG. 4  is a perspective view taken of the existing above-ground swimming pool  22  with automatic raising and lowering retrofit hard cover  24  in the lowered position. The linear actuators  12  shown in ( FIG. 3 ) were not commanded by the linear actuator power source/controller  20  shown in ( FIG. 3 ) to extend upwards. Therefore the retrofit hard cover  24  remains in its lowered position on top of the existing above-ground swimming pool  22 . 
         [0038]      FIG. 5  is a perspective view taken of the existing in-ground swimming pool  25  with automatic raising and lowering retrofit hard cover  24 . The retrofit hard cover  24  is raised off of the existing in-ground swimming pool  25  because the linear actuators  12  were commanded by the linear actuator power source/controller  20  to extend upwards. The upward extension of the linear actuators  12  manifests as a result of the actuator tubular compression members  15  moving up in relation to the bottom of the actuator bases/housings  23 , until the actuator tubular compression members  15  obtain their pre-determined height. 
         [0039]      FIG. 6  is a perspective view taken of the existing in-ground swimming pool  25  with automatic raising and lowering retrofit hard cover  24  in the lowered position. The linear actuators  12  shown in ( FIG. 5 ) were not commanded by the linear actuator power source/controller  20  to extend upwards. Therefore the retrofit hard cover  24  remains in its lowered position on top of the existing in-ground swimming pool  25 . 
         [0040]      FIG. 7  is a top view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as a convex dome  26 . This convex dome  26  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0041]      FIG. 8  is a front view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as a convex dome  26 . This convex dome  26  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0042]      FIG. 9  is a top view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as a multi-faceted pitched from center  27 . This multi-faceted pitched from center  27  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0043]      FIG. 10  is a front view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as a multi-faceted pitched from center  27 . This multi-faceted pitched from center  27  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0044]      FIG. 11  is a perspective view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as a multi-faceted pitched from center  27 . This multi-faceted pitched from center  27  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0045]      FIG. 12  is a top view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as flat pitched  28 . This flat pitched  28  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0046]      FIG. 13  is a side view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as a flat pitched  28 . This flat pitched  28  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0047]      FIG. 14  is a perspective view of a hard cover and/or retrofit hard cover that has a specific geometrical shape that applies to it, which is hereby described as a flat pitched  28 . This flat pitched  28  shape applies to the hard cover  11  shown in ( FIG. 1 ) and the retrofit hard cover  24  shown in ( FIGS. 3 and 5 ). 
         [0048]      FIG. 15  is a cross section view of the vertical support with integral actuator base/housing  16  shown in ( FIG. 1 ). The vertical support with integral actuator base/housing serves two purposes. It serves to act as the linear actuator base/housing, while also providing vertical support for the pool side wall  19  shown in ( FIG. 1 ). 
         [0049]      FIG. 16  is a top view of the circular shape that applies to the above-ground swimming pool  10  shown in ( FIGS. 1 and 2 ), the existing above-ground swimming pool  22  shown in ( FIGS. 3 and 4 ) and also the existing in-ground swimming pool  25  shown in ( FIGS. 5 and 6 ). 
         [0050]      FIG. 17  is a top view of the square shape that applies to the above-ground swimming pool  10  shown in ( FIGS. 1 and 2 ), the existing above-ground swimming pool  22  shown in ( FIGS. 3 and 4 ) and also the existing in-ground swimming pool  25  shown in ( FIGS. 5 and 6 ). 
         [0051]      FIG. 18  is a top view of the rectangular shape that applies to the above-ground swimming pool  10  shown in ( FIGS. 1 and 2 ), the existing above-ground swimming pool  22  shown in ( FIGS. 3 and 4 ) and also the existing in-ground swimming pool  25  shown in ( FIGS. 5 and 6 ). 
         [0052]      FIG. 19  is a top view of the oval (slot) shape that applies to the above-ground swimming pool  10  shown in ( FIGS. 1 and 2 ), the existing above-ground swimming pool  22  shown in ( FIGS. 3 and 4 ) and also the existing in-ground swimming pool  25  shown in ( FIGS. 5 and 6 ). 
       REFERENCE NUMERALS 
       [0000]    
       
           9 —rigid transparent material (polycarbonate, acrylic sheet) 
           10 —above-ground swimming pool 
           11 —hard cover 
           12 —linear actuators 
           13 —hard cover frame 
           14 —actuator to frame connector 
           15 —actuator tubular compression members 
           16 —vertical support with integral actuator base/housing 
           17 —top seat 
           18 —seat cover 
           19 —side wall 
           20 —linear actuator power source/controller 
           21 —fluid or electric transmission line/hose 
           22 —existing above-ground swimming pool 
           23 —actuator base/housing 
           24 —retrofit hard cover 
           25 —existing in-ground swimming pool 
           26 —convex dome 
           27 —multi-faceted pitched from center 
           28 —flat pitched 
           29 —vertical support 
       
     
       Operation 
       [0074]    In operation one will the gain access to the above-ground swimming pool  10 , existing above-ground swimming pool  22  or existing in-ground swimming pool  25  by using a security code or key to turn on the linear actuator power source/controller  20 , then push the up button on the linear actuator power source/controller  20  to command the hard cover  11  or retrofit hard cover  24  to raise. When the above-ground swimming pool  10 , existing above-ground swimming pool  22  or existing in-ground swimming pool  25  user is finished, they will push the down button on the linear actuator power source/controller  20  to command the hard cover  11  or retrofit hard cover  24  to lower and cover the above-ground swimming pool  10 , existing above-ground swimming pool  22  or existing in-ground swimming pool  25  until next use. 
         [0075]    The hard cover  11  and retrofit hard cover  24  in the lowered position will keep children, animals, unwanted guests, pollutant rain and debris such as dust and leaves from entering the above-ground swimming pool  10 , existing above-ground swimming pool  22  or existing in-ground swimming pool  25 . 
         [0076]    The linear actuators  12  used to raise and lower the hard cover  11  or retrofit hard cover  24  can be telescopic or non-telescopic and actuated through the use of mechanical (screw jack, rack and pinion or pulley types), hydraulic (piston type), pneumatic (piston type), electro-mechanical, Piezoelectric and linear motor devices. 
         [0077]    When the rigid transparent material  9  of hard cover  11  and retrofit hard cover  24  do not have UV filters in them or a photochromic coating applied to the outer surface, the suns&#39; ultra-violet rays are not filtered out. Therefore the refracted sunlight is concentrated onto the surface of the pool water. The combination of refracted sunlight and encapsulating the pool water with the hard cover keeps the water in the pool warmer. 
         [0078]    When the rigid transparent material  9  of hard cover  11  and retrofit hard cover  24  has UV filters in them or a photochromic coating applied to the outer surface, the suns&#39; ultra-violet rays are filtered out. The purposes or advantages of blocking the suns&#39; ultra-violet rays are as follows:
         1 ) The skin of swimmers that are under the raised hard cover  11  and retrofit hard cover  24  are protected from the suns&#39; harmful ultra-violet rays.     2 ) Will keep the water in the above-ground swimming pool  10 , existing above-ground swimming pool  22  or existing in-ground swimming pool  25  cooler.     3 ) The lack of UV rays will discourage the growth of algae.

Summary:
An above-ground swimming pool with integral automatic raising and lowering hard cover, and an automatic raising and lowering retrofit hard cover for an existing in-ground and above-ground swimming pool. The raising and lowering of the hard cover takes place with the utilization of two or more linear actuators that are telescopic or non-telescopic and actuated through the use of mechanical (screw jack, rack and pinion or pulley types), hydraulic (piston type), pneumatic (piston type), electro-mechanical, Piezoelectric and linear motor devices. The hard cover provides several benefits to the user of the pool.