Abstract:
An inflatable device is provided including an inflatable framework for a projection screen or imaging surface wherein an additional support structure provides increased stability for the inflatable framework and the screen while avoiding contact or interference with the screen or imaging surface, thereby limiting screen distortion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     FIELD OF THE INVENTION 
     This invention relates to inflatable devices that hold or include projection or imaging screens. 
     BACKGROUND OF THE INVENTION 
     Inflatable structures used with projection or imaging screens are known in the art. United States Patent Publication 20100007949 and U.S. Pat. No. 7,446,937 describe examples of inflatable screens. Inflatable screen devices can be quite large and are often used in outdoor environments. Therefore, the stability of inflatable screens is important. 
     Inflatable screen devices generally include an inflatable framework that is used to hold up and secure the screen surface. The inflatable structure may be held to the ground by guy wires or tethers that run from the inflatable structure to anchor points on or in the ground or ballast. This prevents the inflatable structure from moving along the ground or falling. However, the screen surface and/or framework may bend, curve, or bow due to structural design, large size, torsion (i.e., when the weight is different on the front and back of structure), and the influence of wind. It is highly desirable for the screen projection surface to remain flat and rectangular during use so that the projected images appearing on the screen are not distorted. Prior art attempts to keep screen projection surfaces flat and rectangular during use have included structural elements, such as one or more support columns centered or distributed vertically in the framework. In the prior art, these elements have been placed in or close to the plane of the framework and the projection screen surface to reduce some of the displacement of the framework and screen due to wind or other forces. In the prior art designs, the screen surface may come into contact with such a support structure as the wind pushes against the screen from the front, which can cause visually apparent distortion of the projection screen surface and projected images. 
     Thus, a need exists for a support mechanism for inflatable screen devices that reduces displacement and distortion of the framework and projection screen surface due to wind or other forces while minimizing interference with the screen when the wind pushes against the screen surface from the front. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an additional support structure for an inflatable device for holding up a projection screen surface comprising an inflatable framework on which a projection screen for images is held, wherein the additional support structure attaches to upper and lower portions of the inflatable framework such that displacement of the framework and screen due to the wind will be reduced and wherein the additional support mechanism bends, curves, or angles away from the plane of the screen and the inflatable framework in the area of the screen. 
     It is a further object of the invention to provide one or more additional support structures that are inflatable. 
     It is a further object of the invention that the additional support structure(s) has an air bladder that is separate from air bladders of the inflatable framework. 
     It is a further object of the invention that air pressure within the air bladder of the additional support structure(s) can be varied to adjust for different or changing environmental and other conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art inflatable device and screen. 
         FIG. 2   a  is a side view of a prior art inflatable device and screen under the influence of wind. 
         FIG. 2   b  is a perspective view of a prior art inflatable device and screen under the influence of wind. 
         FIG. 3  is a perspective view of an embodiment of the invention. 
         FIG. 4  is a side view of an embodiment of the invention. 
         FIG. 5  is a perspective view of another embodiment of the invention. 
         FIG. 6  is a perspective view of another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows an inflatable device  1  for showing images on a screen  2  according to the prior art. The inflatable device  1  can be erected on a temporary basis in indoor or outdoor environments. The inflatable device  1  includes an inflatable framework  3  that can include a top  4 , bottom  5 , and side ( 6   a ,  6   b ) portions. A blower  7  is used to inflate the framework  3  and a series of guy wires (not shown) can be attached to the framework  3  in order to hold the framework  3  in place. The screen  2  is attached to the framework  3  by any suitable means that are designed to stretch the screen  2  and hold the screen  2  in a flat position. Once the framework  3  is fully inflated and secured, a movie, video, or other images can be displayed on the screen  2 . 
       FIG. 2   a  shows prior art inflatable device  1  under the influence of a wind  8  blowing into the back of inflatable device  1 , causing the screen  2  to billow and be displaced out of the plane of the framework  3 .  FIG. 2   b  shows prior art inflatable device  1  under the influence of wind  8  blowing into the back of inflatable device  1 , causing the screen  2  to be displaced forwardly out of the plane of the framework  3  and causing top portion  4  of the framework to bend downward. The displacement of the screen  2  and top portion  4  of the framework  3  is undesirable as it can cause distortion of the images shown on the screen  2 . 
       FIG. 3  depicts an embodiment of the present invention. The framework  30  of inflatable device  10  can be made of plastic vinyl material or other suitable material that can be sewn or heat welded together. The framework  30  is inflated using a blower  70  or other known method of inflation. Framework  30  comprises a top  40 , bottom  50 , and side ( 60   a ,  60   b ) portions. A screen  20  can be attached to framework  30  and stretched flat. A series of guy wires (not shown) can be attached to framework  30  in order to hold it in place during inflation and after inflation. 
       FIG. 3  also shows an additional support structure  21 . Support structure  21  can be attached, by heat welding, sewing, hook and loop fastener or other suitable means, to top portion  40  on one end and at the other end to bottom portion  50  of framework  30  of inflatable device  10 . The attachment mechanism can be reversible or more permanent. Support structure  21  can be made of plastic vinyl or other suitable materials. Support structure  21  is shaped such that it bends, curves, arches, or angles so that support structure  21  generally avoids the plane formed by the framework  30  in which screen  20  resides.  FIG. 4  provides a side view of an example of an embodiment in which support structure  21  angles away from framework  30  near the top  40  and bottom  50  portions. The shape of support structure  21  is also designed so that it can function to square the framework  30  by supporting top portion  40  when the force of wind on screen  20  might otherwise cause top portion  40  to bend downward or bend downward more. Such support is provided by support structure  21  whether the wind is blowing from the front or rear of the inflatable device  10 . 
     In a preferred embodiment, support structure  21  is an inflatable structure that has an air bladder that is separate from any air bladders of framework  30 . In this manner, the air pressure in support structure  21  can be adjusted for the conditions. For example, an increase in wind speed could create a greater downward force on top portion  40 . An increase in the air pressure in support structure  21  would tend to create an upward force against top portion  40  that could counteract the downward force caused by the wind and keep the framework  30  more square, which would also reduce the amount that screen  20  is displaced. 
     In addition, more than one of the support structures of the present invention can be used to provide support for the framework, as shown for example in structures  22  and  23  of  FIG. 5 . Further in addition, variations on the shapes of the support structures can be used provided the structure serves the function of squaring the framework and generally avoids the plane of the screen. In  FIG. 6 , for example, a “Y” shaped support structure  24  is shown.