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: 
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to collapsible enclosures adapted for use by one or two people on a beach or other generally level surface, in particular such enclosures which can provide protection against sand or small objects kicked or thrown by others.  
         [0002]     The desirability of providing some portable shelter-like protection for people resting or sun-bathing on a beach or lawn has long been recognized. U.S. Design Pat. Des. 288,613 shows a combined shelter and comfort unit formed by flat wall and floor panels stretched over frames. The panels appear to be fabric with transparent window portions, and contain sleeve portions through which rigid tubing frame parts are passed. In addition to substantial cost, structures like this have the disadvantage that the frame parts, while flat, have an overall length and width equal to the shelter&#39;s width and height. As a result, even if the fabric can be readily slipped off some tubing sections so that a plurality of flat sections are formed, in a disassembled condition the shelter is bulky unless the frames pull apart into a large number of straight and/or corner lengths. The latter arrangement requires a large bag to hold all the parts, and substantial time by one or two people to assemble or disassemble. If just one part becomes lost, the shelter cannot be erected.  
         [0003]     Many kinds of inflatable boats, floats and beach toys or furniture have been designed and sold but none of these are suitable for a simple shelter which requires no long or rigid poles to define a useful shape.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     According to the invention, a beach enclosure is formed by an integral unit having an inflatable tube forming walls defining a protected space having a closed end and an open end, and having flaps arranged for holding the enclosure in place.  
         [0005]     In a first embodiment of the enclosure the flaps extend exteriorly of the protected space and are formed as pouches which the user can fill with sand or small rocks.  
         [0006]     In another embodiment the enclosure includes a floor section extending between and integral with the walls, thereby providing a sand-free space. The floor section may also be inflatable to provide greater comfort.  
         [0007]     In a configuration for single person use, the walls define a rectangular enclosure having one end wall and two side walls longer than the end wall, and the inflatable tube is generally circular in cross section. In an alternative embodiment providing greater protection, at increased cost, each wall may be formed by two or more tubes generally parallel to each other, such that when inflated the height of the wall is at least approximately twice its thickness.  
         [0008]     In a further embodiment, the basic enclosure includes attaching elements for an extension unit for extra-tall people. The extension unit may be flat and may have a transverse tube at its remote end which can be filled with water.  
         [0009]     In yet another embodiment, at least one tube has at least one cup holder. The cup holder may be fastened to the tube by a hook-and-loop fastener such as Velcro, or may preferably be formed as a cylindrical or frusto-conical depression in the top surface of the tube.  
         [0010]     In another embodiment of the enclosure the flaps are formed with stabilizing tubes of smaller cross-section than a wall tube, which the user can fill with liquid such as water. These tubes may be disposed exteriorly of the protected space, and may be generally parallel and close to the tubular walls. The stabilizing tubes may also be arranged within the protected space.  
         [0011]     When the stabilizing tubes are within the protected space, they may be arranged partially underneath the wall tubes so that the stabilizing tubes are out of the user&#39;s way; or such a tube may extend crosswise near the closed end, and thereby also serve as a pillow for a user&#39;s head.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0012]      FIG. 1  is a perspective view of a simple shelter according to the invention;  
         [0013]      FIG. 2  is a plan view of a shelter according to the invention having additional comfort and convenience features;  
         [0014]      FIG. 3  is a side elevation of the shelter of  FIG. 2 ;  
         [0015]      FIG. 4  is a partial plan view of an alternative pouch arrangement for the shelter of  FIG. 2 ;  
         [0016]      FIG. 5  is a plan view of a variation of the shelter of  FIG. 2  having a water tube for holding the enclosure in place, and room for two people;  
         [0017]      FIG. 6  is a partial plan view of an alternative water tube arrangement for the shelter of  FIG. 5 ;  
         [0018]      FIG. 7  is a side elevation of a shelter variation having a plurality of tubes to provide greater height;  
         [0019]      FIG. 8  is a plan view of an extension unit for the embodiment of  FIG. 2 ; and  
         [0020]      FIG. 9  is a partial plan view of a variation of the extension unit of  FIG. 8 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     As shown in  FIG. 1 , in a very simple form an inflatable enclosure according to the invention includes a cylindrical tube  2 , round in cross section when inflated, and four flaps  4  each having a hole  5  for inserting a stake to hold the enclosure in place. An air valve  7  is provided for inflating and deflating the tube. The tube may be made from a sheet of thermoplastic material, with seams to define the desired shape, formed in any well-known way such as gluing or thermo-compression welding. The tabs  4  are desirably formed from the same material, but preferably are two layers thick, are attached by gluing or welding to the bottom surface of the side wall portions  9  of the tube  2 , and extend exteriorly with respect to the space  8  between the side wall portions. Each hole  5  may be reinforced by a weld line around its edge, or may have a plastic or metal grommet permanently fastened in the hole. To provide a clean surface for a person to sit or recline, a floor  11  made of the same material as the tube may be glued or welded to the bottom surface of the tube  2 , so as to be integral with the tube.  
         [0022]     In  FIG. 1 , as in the other figures of the drawing, for simplicity the tube is shown as having square comers. For maximum strength and economy in manufacture the tube  2  will usually have seams and comers whose exact shape is dictated by the gluing, welding, or other technique used.  
         [0023]     The embodiment of  FIG. 1 , especially if sold without the floor, requires a minimum of material and manufacturing operations. In a convenient size with a tube diameter of approximately one foot, and a space 3 feet wide by 6 feet long, the deflated enclosure can be folded into a very small size. If packaged with any widely available pump, such as a foot operated accordion pump  13  connectable to the air valve  7  by a flexible air line  14 , the combination will be very compact and easy to carry. Preferably the air line  14  is permanently connected to the air pump  14 , and plugs into the air valve  7  to inflate the tube  2 . When inflation is complete, the air line may be removed and the valve  7  closed in any well known fashion, such as by insertion of a plug which is permanently attached to the valve by a short length of flexible plastic.  
         [0024]     To be stable in place, and not be lifted or shifted by a breeze, the enclosure of  FIG. 1  requires stakes. For use on sand, these may be simple plastic pins having a head to press down against the grommet. However, they are auxiliary items which are likely to be lost.  
         [0025]     The embodiment of  FIGS. 2 and 3  provides additional comfort and convenience features at little increase in cost. A tube  22  is similar to the tube  2  but has holders  23  for beverages or other items molded into the top surface of the tube, preferably made of the same material as the tube  22  and spaced along the side walls  29 . A single long flap  24  extends outwardly from the bottom of each side wall  29 . Each flap has a plurality of pouches  26  formed thereon, arranged so that a user can fill them with sand or small rocks, either before or after the enclosure has been inflated. Only two pouches  26  are shown on each flap in this figure, but a greater number may be desirable. In this embodiment the pouches are formed by holding pieces of thermoplastic material in an arched shape to define spaces under the pieces, and attaching each piece of material to the flap by a glue or weld line  26   a  running along the outside edge of the tab and then extending toward the adjacent tube so that the lower surface of the adjacent tube will reduce spillage of sand or rocks from the pouch while the shelter is being occupied.  
         [0026]     The holders  23  can be identical, or one or two shown as holder  23   a  in  FIG. 3  can be deep enough to hold a typical 12 ounce beverage container stably, while others can be shallow as 1 1/2  or 2 inches deep.  
         [0027]     At least one valve  27  is provided for inflating the tube  22 .  
         [0028]     To provide greater comfort when the beach or other surface is not fine sand, the shelter of  FIG. 2  can have an inflatable floor  31  formed by upper and lower sheets of the same material as the tube  22 , glued or welded to the bottom surface of the tube. One of these surfaces can be the same sheet of material as the flap  24 . A pattern of weld or glue lines (not shown) can be formed between the upper and lower sheets so that the floor does not balloon up greatly in some areas when a person rests on another part of it. To minimize the need for strength, and resulting higher cost of the floor material, the pattern may tend to limit the inflated floor height to as little as ¼ inch. Because floor and tube pressure may be desirably different, a separate valve  37  is provided for inflating the space between the upper and lower sheets.  
         [0029]     A utility pouch  38  for a user&#39;s personal articles, shown diagrammatically, is provided at each of the closed end comers. This may be permanently glued or welded in place, or may be removably attached by hook-and-loop patches, snaps, or other well known devices.  
         [0030]     A through opening  39  can be provided in the floor panel for the pole of a beach umbrella or the like. Particularly if the hole is reinforced with a grommet, a user&#39;s weight on the floor of the shelter will stabilize an umbrella pushed into sand below the shelter, thereby reducing the annoying tendency of these umbrellas to tip from the desired angle  
         [0031]      FIG. 4  shows an alternative way to form pouches  46 , by cutting the flap material so as to leave a series of regions  41  shown by dashed lines protruding from the main area of the flap  44 . The region  41  can then be folded over along the dashed line  42  and its middle arched upward, for example so that edges  43  lie along the lines  45 , and glued or welded along the lines  45 . The resulting pouch  46  retains the arched shape because the edge  47  is longer than the line  48  as shown in the plan view. Like the pouches  26 , each pouch  46  can easily be filled with sand or the like, or a rock or other locally available object of suitable size and weight can be placed in it.  
         [0032]      FIG. 5  shows a shelter generally like  FIGS. 2 and 3 , but with a different arrangement for holding the shelter in place, different arrangements for beverage holders or utility holders, and being shown with a wider protected space so that it can be occupied by two people. Tube  52  is similar to tube  22  except that the closed end may, for example, be 2 feet longer. Flaps  54  extend exteriorly from the bottom of side walls  59 . Instead of pouches  26 , each flap has a long tube  56  with a filling opening  57 . The tube  56  can be filled with water, or any convenient liquid, by the user. Advantageously, if the floor  51  has upper and lower layers, these are continuous sheets of material which also form the upper and lower layers of the tubes  56 , the tubes being defined by glue or welding lines  56   a.    
         [0033]     Instead of molded-in cup or utility holders  23 , in the embodiment of  FIG. 5  fastener patches  53  are provided, for temporary attachment of different size or style holders exteriorly of the tube  52 .  
         [0034]     In an alternative construction of a shelter basically similar to that of  FIG. 5 , as shown in  FIG. 6  the glue or welding attachment of the sheets to the bottom of the walls  69  can connect the sheets together, and define one long seam at the inner side of the tubes  66  so that only end seams  66   a  are additionally required. Further, like the embodiment of  FIG. 4 , one outside edge  62   a  can be defined by folding a long strip of material over to provide the upper and lower layers.  
         [0035]     The embodiment of  FIG. 7  provides an enclosure whose height is at least double the wall thickness (tube diameter), through the use of an upper tube  72  and a lower tube  73 , each having substantially the same generally circular cross section. To make the open end more rigid, the upper tube  72  may be made with a vertical portion  70  extending downward, with a glue or weld line connecting that portion to the end of the lower tube. The upper tube  72  and the lower tube  73  can be independent air chambers attached by a glue or weld line or a web of the same material as the tubes, and each having its own air valve  77 . Alternatively, the air chambers formed by the two tubes can be connected by one or more openings aligned with each other where the two tubes touch, and likewise glued or welded. Because of the greater effect of wind on the higher walls, preferably this embodiment has larger stabilizing pouches  76  than the enclosure of  FIG. 2 .  
         [0036]     While the double wall height of  FIG. 7  will increase the shelter cost significantly, this extra protection will be especially desirable if the shelter is made wider, like that of  FIG. 5 , so that it can comfortably be occupied by two people.  
         [0037]     People who are well above average height often find that, while ready-made clothing is available in sizes to fit almost everybody, recreational and other devices are often sold in one size only and are less than fully satisfactory for tall people. To enable an inexpensive shelter according to the invention to provide greater comfort, the extension unit of  FIG. 8  provides a clean smooth surface for the feet and lower legs. Alternatively this unit allows the user to use some of the protected space remote from the open end for personal items such as spare clothing or a food basket which is therefore less apt to be dirtied or contaminated by sand or the like kicked up by others in the area. This is particularly effective because the basic enclosure is large enough to be noticed by others using the beach.  
         [0038]      FIG. 8  shows an extension unit  180  having a central floor  188  which may be a single layer of the same material as used for the inflatable enclosure. Extending from the floor  188  are side portions  184 , and an end flap  189  which will fit under the floor  31  of the embodiment of  FIG. 2 . For attaching the extension unit to the basic shelter each side portion  184  has a further portion  194 , shown at the left in this view extending in the direction of the end flap, and an attachment patch  195  which as shown at the left in this figure is on the under side of the portion  194 . The further portion  194  is shown at the right folded back over the flap  184  The patch  195  is preferably the hook portion of a hook-and-loop combination. For attachment of the extension unit  180  to the basic enclosure, each side wall portion  29  of the enclosure has a mating loop piece  195 ′ shown in  FIG. 2  on its end wall. To connect the extension unit, the portion  194  is bent upward so that the patch  195  is aligned with the piece  195 ′ and they are pressed lightly together.  
         [0039]     It will be clear that the choice of hook portion or loop portion may be interchanged. However, a user&#39;s clothing is less apt to catch on or cling to the loop portion if this is on the base unit, which is exposed when an extension unit is not attached.  
         [0040]     To keep the extension unit lying flat, it has a long tube  196  extending substantially from the outer edge of one side portion  184  to the opposite outer edge. The tube may be filled with water through a valve  197 . With this arrangement the tube  196  serves both to weight the end of the unit  180  down and stabilize it in position, and it also provides a desirable degree of stiffness to the end of the unit  180 . If the user is at a beach or pool, the tube  196  can easily be filled with water before arranging the unit  180  with respect to the enclosure and connecting the attachment patches.  
         [0041]     Alternatively, as shown in  FIG. 9  an extension unit  200  is like the unit  180  except for having holes  205  at two corners of a floor  208 , and the side portions  204  may have pouches  206  similar to the pouches  26  or  46 .  
         [0042]     It will be clear to those of ordinary skill in the art that many variations of these embodiments can be provided, still utilizing the invention covered by the appended claims. For example, more than one opening can be provided in the floor panel so that flags or a small canopy can be erected where or when desired. Additional or different kinds of pouches, pockets, depressions or attachment points can be provided in convenient locations to allow placement of food containers, small clothing items, or safe storage of articles which are easily lost or damaged such as eyeglasses which one sometimes needs at a beach.  
         [0043]     Rather than hook-and-loop patches, snap fittings or any inexpensive type of easy connecting/disconnecting fastener can be provided. This can be especially desirable for an extension unit.  
         [0044]     Further, the claimed enclosure can be used advantageously on lawns or other places where some temporary shelter is desired, and the exact location of attachments, patches or pockets can be optimized for particular uses.  
         [0045]     The parts for holding the enclosure in place can be provided at the interior sides of the tube instead of, or in addition to, the placement shown. If a flap is on the inside at the closed end, and is filled with water, this can serve not only to hold the shelter in place, but also be a pillow. Forming it as a flap rather than-an integral part of the floor can make filling it easier. Such a flap can alternatively be attached to the inner side of the tube  22 . If it is near the bottom it can occupy what may otherwise be unusable space between the floor and the lower half of the tube. More or differently placed air valves can be provided, and the tube can be divided into a plurality of chambers. When the shelter has a double wall floor with a fill valve, many different designs of weld or partitioning lines can provide ornamental appearances as well as control the tendency of an inflated floor to bubble up around a user&#39;s body.  
         [0046]     The rectangular shape shown is efficient for a person lying down. However, a round or rounded end may be easier to fabricate. The dimensions mentioned above are believed a desirable compromise between too little height, such that kicked, thrown or blown sand or the like would annoy a user, and a large size which is easily blown by gentle breezes. A smaller enclosure, on the other hand, may be useful to provide some protection for a small child.

Summary:
An inexpensive enclosure providing a protected space on a beach, lawn or the like. An inflatable tube forms a wall surrounding a space having an open end, so that a user is shielded from small kicked or thrown material or objects, running pets and the like. The tubular wall has flaps extending from its bottom surface, with pouches or separate tubes which a user fills at the site to hold the enclosure in place. The enclosure may have a floor, and may have attachment portions for removably connecting an extension unit having a floor which extends beyond the open end of the space between side portions of the wall.