Abstract:
The rigid balloon has a chamber to hold lighter-than-air gas portions to retain a structural member or members and a separate light gas is filled into the chamber through a valve in the balloon. Structural members are inserted into the portion to help retain the desired shape of the balloon. The structural members also provide a counterbalancing weight which prevents the balloon from floating upward. Thus, the balloon, once released into the air, will retain its shape and remain floating at the height from which it was released unless repositioned.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from and is a continuation-in-part of U.S. Non-provisional patent application Ser. No. 10/366,387, filed Feb. 14, 2003 now U.S. Pat. No. 6,659,838, entitled RIGID HELIUM BALLOONS, the contents of which are incorporated by reference herein in their entirety. 

   BACKGROUND 
   1. Field of the Invention 
   The present invention relates to lighter-than-air balloons, and more particularly, to lighter-than-air balloons having a rigid skeleton. 
   2. Description of the Related Art 
   Generally, it has been difficult to fabricate balloons with continuously curved shapes, and well-defined corners, or edges. Most balloons are formed in spherical shapes in order to allow the greatest volume for the least surface area. Also, the thin material of the balloon naturally becomes spherical as pressure is increased. To achieve the desired non-spherical shape, then, it is necessary to provide a supporting frame to maintain the thin material of the balloon. However, in the past, the weight of such frames, even when the most efficient materials for such purposes were selected, typically required a displaced volume of such size that fabrication for home use or the like would have been impractical. Consequently, helium balloons are typically formed in spherical shapes with some type of tethering device attached for maintaining control of the balloon&#39;s elevation. 
   U.S. Pat. No. 4,032,086, issued Jun. 28, 1977 to W. Cooke, discloses an aerostat or aquastat in which a sealed envelope of flexible material is mounted on a flexible frame which can be caused to expand the envelope after it has been evacuated of internal gas, thereby setting up a vacuum or partial vacuum condition in the envelope. By controlling the frame to adjust the volume of the envelope, the lift or buoyancy of the device can be controlled in flight or precisely determined before ascent. 
   U.S. Pat. No. 4,038,777, issued Aug. 2, 1977 to S. Schwartz, discloses a gas filled, balloon-like object capable of defining a non-spherical shape. A high modulus graphite impregnated epoxy material is used to prevent distortion of the inflated object. Strings or weights are required to prevent upward ascent of the balloon. 
   U.S. Pat. No. 4,113,206, issued Sep. 12, 1978 to D. Wheeler, discloses a lighter-than-air apparatus, including a thin, pliable air-tight cuter envelope disposed in overlying relationship over a light-weight, coarse-opening inner frame of a spherelike shape. 
   Other devices relating to balloons and lighter-than-air apparatuses include U.S. Pat. No. 2001/0003505 A1 issued Jun. 14, 2001 to T. Bertrand, which discloses a lighting apparatus secured to a balloon by string under tension; U.S. Pat. No. 4,925,426 issued May 15, 1990 to C. Lovik, which discloses an open skeletal frame of rigid rod-like formers made of thin strands of plastic, wire, or the like and which permits the insertion of an uninflated balloon of conventional shape and size into the interior thereof so that upon inflation of the balloon, the latex sidewall material of the balloon projects outwardly through the openings of the formers to produce bulbous projections; U.S. Pat. No. 5,115,997, issued May 26, 1992 to J. Peterson, which discloses a tethered surveillance balloon having a relatively low lift-to-weight ratio; U.S. Pat. No. 5,115,998, issued May 26, 1992 to L. Olive, which discloses a double-walled, annular balloon which requires less gas to inflate than its volume would indicate; U.S. Pat. No. 5,334,072, issued Aug. 2, 1994 to M. Epstein, which discloses an inflatable body, such as a balloon, and holder assembly therefore; U.S. Pat. No. 5,882,240, issued Mar. 16, 1999 to B. Larsen, which discloses a toy blimp; U.S. Pat. No. 6,276,984, issued Aug. 21, 2001 to K. Komaba, which discloses a balloon having adhering members disposed upon its surface; Japanese Patent No. 1238890, published Sep. 25, 1989, which discloses plastic film balloons in animal and other complex shapes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. 
       FIG. 1  is an environmental, perspective view of a rigid helium balloon according to the present inventor. 
       FIG. 2  is a section view along lines  2 - 2  of  FIG. 1 . 
       FIG. 3  is a perspective view of a rigid helium balloon according to the present invention. 
       FIG. 4  is a diagram of an alternative embodiment of the rigid balloon. 
       FIG. 5  is a diagram of an alternative embodiment of the rigid balloon. 
       FIG. 6  is a diagram of a sleeve to retain a structural member in one embodiment of the rigid balloon. 
   

   Similar reference characters denote corresponding features consistently throughout the attached drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is an environmental, perspective view of a rigid helium balloon according to the present inventor. As shown in  FIG. 1 , one embodiment of the balloon, generally designated as  10 , is relatively small and can be easily adapted as a toy for indoor use. As depicted in  FIG. 2 , the balloon  10 , is made from skin portions  12  and  14 , e.g., a top half and a bottom half of the balloon  10 . The skin portions  12  and  14  may be formed in any shape desired for the balloon  10 . In the embodiment depicted in  FIGS. 1-2 , the skin portions  12  and  14  are shaped so that when the top half  12  and bottom half  14  are joined, the resulting balloon  10  is a lenticular-shaped balloon which resembles a flying saucer. Skin portions  12  and  14  can be made from any suitable heat sealable material which has low gas permeability. In one embodiment, skin portions  12  and  14  are made from polyethylene terephthalate (sold under the trademark Mylar®, a trademark of E.I. duPont de Nemours &amp; Co. of Wilmington, Del.). 
     FIG. 2  is a section view along lines  2 - 2  of  FIG. 1 . As can be more clearly seen in  FIG. 2  in this embodiment, the skin portions  12  and  14  are sealed together in a double seam about their periphery, including a first peripheral seam  16  and a parallel or concentric second seam  18 . First seam portion  16  and second seam portions  18  are disposed near the peripheral edges of the first and second skins  12  and  14 , and are spaced from one another. First seam portion  16  and second seam portion  18  are formed by heat sealing or any other suitable means. A channel portion  20  is defined between seam  16  and seam  18  and extends about the periphery of the balloon  10 . Skin portions  12  and  14 , when joined, define a chamber  22  therebetween which may be filled with a lighter than air gas such as helium. The chamber  22  includes a valve  24  through which the balloon  10  may be filled with the lighter than air gas. The valve  24  may be one which is commonly used in Mylar balloons, although any suitable valve may be used. 
     FIG. 3  is a perspective view of a rigid helium balloon according to the present invention. As can be seen in  FIG. 3 , at least one structural member  26  is inserted into the channel portion  20  through apertures  28 . While the structural member  26  can be formed from any acceptable material, in one embodiment it is made from fiberglass. In another embodiment, the structural member  26  is molded or extruded from a thermoplastic or other polymer. Once the structural member  26  has been inserted through the channel portion  20 , opposing ends  30  of the structural member  26  can be joined together by a connector  32  to secure the structural member  26  in place. Any suitable connector  32  may be used to join the ends  30  of the structural member  26 . In one embodiment, a brass fitting having a diameter slightly larger than the diameter of the structural member  26  is used. Alternatively, the structural member may be manufactured in a desired shape such as a ring. The ring may be placed adjacent to first seam  16  around the chamber before second seam  18  is formed. Second seam  18  may then be formed to retain the structure member  26 . In such an embodiment, no connector is required. 
   Once the structural member  26  is secured in the channel portion  20 , the structural member  26  provides a substantially rigid skeleton for the balloon  10  so that the balloon  10  may maintain its desired shape once it has been inflated with gas. The rod member  26  has a weight which is calculated to counterbalance the buoyant effect of the gas so that the balloon  10  is prevented from floating upwards when filled, the balloon  10  simply floats at the height at which it is released. Stated differently, in one embodiment, the weight of the rod (and any connector) is selected to cause the balloon to be neutrally buoyant under ambient conditions when the chamber is inflated to a known pressure with a lighter than air gas. 
   Although only one structural member  26  is depicted in the drawings, for some shapes, it may be necessary to use a plurality of structural members  26  of varying sizes (not shown). For such shapes, for example those with a plurality of curves or angles, a plurality of apertures may be provided at various points on the balloon  10  so that the structural members  26  may be easily inserted into the channel portion  20 . The structural members  26  can then be connected to one another using the connector  32 , as previously described. 
     FIG. 4  is a diagram of an alternative embodiment of the rigid balloon. As shown in  FIG. 4 , instead of creating (or in addition to) a channel for the structural member at the junction between the two skins, a plurality of strips  130  may be attached to the external surface of the flexible material covering the chamber and by either threading the structural member  126  through the loops formed by attaching the strips  130  around the structural member, the structural member  126  is retained and provides a skeleton for the balloon  110 . 
     FIG. 5  is a diagram of an alternative embodiment of the rigid balloon. In this embodiment, the chamber is again constructed of one or more pieces of flexible low permeability material. The flexible material may be assembled to form the chamber by heat welding; adhesive or any other manner that results in a low gas permeability ultimate chamber. In one embodiment, one or more sleeves may be coupled to the external surface of the material defining the chamber to provide receptacles for one or more structural members  226 . Again, this coupling may be accomplished with adhesive, heat welding or any manner that does not substantially degrade the structural integrity of the chamber. Alternatively, pockets may be formed in a manner analogous to that described above. 
     FIG. 6  is a diagram of a sleeve to retain a structural member in one embodiment of the rigid balloon. The sleeve  232  may have one end sealed such as by heat welding. An aperture  336  is defined distal to the sealed end  338 , but short of the opposing end  340 . The structural member  226  having some elasticity may then be inserted into the sleeve  232  to the sealed end  338 . The structural member may then be flexed so the other end of the member can be inserted past the aperture. The natural elasticity of the structural member will then hold it in place against the opposing ends of the sleeve  232 . 
   In one embodiment, additional heat welds are used within the sleeve to provide a well-defined seat  334  for the ends of the structural member  226  to reduce movement of the structural member  226  in the sleeve  232 . In one embodiment, the sleeve is open at both ends and defines a channel for the structural member. A throughway connector may be used to hold the structural member  226  together. For example, the sleeve may run circumferentially around the lenticular shaped balloon described with reference to  FIGS. 1-4 . In one embodiment, the sleeve may be completely sealed at the time of manufacture with the structural member enveloped within. 
   In one embodiment, a structural member may be a rod having substantially any shaped cross section. While rod with circular cross section is suitable for use in embodiments of the invention, square, triangular, dogbone and substantially any other cross sections are contemplated. Structural members having a thickness much less than their length or width are also contemplated. 
   In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.