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: 
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims benefit of and priority to co-pending related Utility patent application Ser. No. 11/820,555 filed Jun. 20, 2007, entitled “PORTABLE SHELTER WITH UNSUPPORTED SPAN AND METHOD OF FORMING”, the disclosure of which is incorporated herein by reference in its entirety. 
   FIELD OF THE INVENTION 
   The present invention generally relates to unsupported spans for use in the fields of portable structures and portable signage. 
   BACKGROUND 
   The use of devices and methods relating to unsupported spans and portable structures are disclosed in U.S. Pat. No. 5,490,532 issued in the name of Mallookis et al., U.S. Pat. No. 6,691,723 B2 issued in the name of Godbersen, U.S. Pat. No. 4,724,882 issued in the name of Wang, U.S. Pat. No. 6,012,505 issued in the name of Wurz et al., U.S. Pat. No. 4,913,428 issued in the name of Nauman, and U.S. Des. Pat. No. 254,809 issued in the name of Celestian. 
   While existing devices suit their intended purpose, the need remains for a device that provides a structure that is formed from materials that are commonly available, and that does not require any specialized tools to assemble and place. 
   The present invention advantageously provides an unsupported span that horizontally spans considerable distances without requiring vertical supports at points throughout the span. Additionally, the present invention provides a high degree of rigidity, due to the tensioning of the structural members forming the unsupported span. Additionally, the present invention does not require any complicated means of adjustment, hinges, bolts, or pins. Elimination of these features in the present invention provides substantial cost savings, and provides a structure that may be easily assembled by a wide variety of users. 
   SUMMARY 
   An unsupported span device for portable structures and portable signage is provided comprising a plurality of vertical members that provide vertical load-bearing capability to the unsupported span; a plurality of horizontal members for providing a bearing surface for a load applied to the unsupported span; means for fixing the location of the plurality of horizontal members with respect to the plurality of vertical members; a tensioning member for inducing tension between the plurality of vertical members; means for fixing the location of the tensioning member with respect to plurality of vertical members; a plurality of tethers for laterally stabilizing the unsupported span; and a plurality of anchors for providing fixed points of attachment for the plurality of tethers. A method of forming an unsupported span is also provided 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, features and advantages of the present invention will become apparent from the following detailed description and the appended drawings in which: 
       FIG. 1  illustrates a perspective view of an unsupported span in accordance with one embodiment of the invention. 
       FIG. 2  illustrates an exploded view of the intersection of a vertical member and a horizontal member of an unsupported span in accordance an embodiment of the invention. 
       FIG. 3  illustrates an exploded detail view of an unsupported span in accordance with one embodiment of the invention. 
       FIG. 4  illustrates a detailed view of an unsupported span in accordance with an embodiment of the invention. 
       FIG. 5  illustrates a detail view of an anchor and cord used for lateral support of an unsupported span in accordance with an embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An unsupported span  10  is provided including a first vertical member  12  and a second vertical member  14 ; an upper horizontal member  16 ; a lower horizontal member  18 ; a means for fixing the location of the upper and lower horizontal members with respect to the vertical members  12 ,  14 ; a tensioning member  20 ; a means for fixing the location of the tensioning member with respect to the vertical members  12 ,  14 ; a plurality of tethers  24 ; and a plurality of anchors  26 . 
   As used herein, a vertical member is defined as a member that is vertically oriented member when positioned perpendicularly with respect to the surface upon which the vertical member is placed. 
   As used herein, a horizontal member is defined as a member that is horizontally oriented when positioned horizontally with respect to the surface upon which the horizontal member is placed. 
   In an embodiment of the invention, the first and second vertical members  12 ,  14  may have a tubular form, wherein the tubular form may have a geometric cross-section defined by a wall of the tubular forms, as illustrated in FIGS.  2 , 3 . The shape of the geometric cross section may include, but is not limited to: round, obround, rectangular, square, and polygonal. 
   Each tubular member that forms each of the first and second vertical members  12 ,  14  is of sufficient strength to allow each respective vertical member to be driven into the ground, either by a user or a machine adapted to perform that operation. Additionally, the first and second vertical members  12 ,  14  are of sufficient strength so as to support a wide range of loads that may be placed thereupon without bending, buckling, collapsing, or otherwise failing. 
   The upper and lower horizontal members  16 ,  18  have a tubular form, wherein the tubular form may have a geometric cross-section, defined by the walls of the tubular forms, as illustrated in  FIG. 3 . The form of the geometric cross section may include, but is not limited to: round, obround, rectangular, square, and polygonal. 
   Each of the respective upper and lower horizontal members  16 ,  18  include an opening defining a hole  28  passing transversely therethrough at a respective first and second end  44 ,  46  of each respective upper and lower horizontal member  16 ,  18 , as illustrated in  FIG. 3 . Each respective opening and hole  28  is located such that it passes through each respective upper and lower horizontal member  16 ,  18  along the centerline of the geometric cross-sectional profile of each respective upper and lower horizontal member  16 ,  18 , and is perpendicular to the longitudinal centerline of each respective upper and lower horizontal member  16 ,  18 . Each of the respective holes  28  is of sufficient size so as to allow passage of one of the first and second vertical members  12 ,  14  therethrough. 
   The tubular members forming the vertical members  12 ,  14  and horizontal members  16 ,  18  may be formed by methods including, but not limited to: extrusion, pultrusion, and roll forming. 
   In another embodiment of the invention, it is contemplated that each respective vertical member  12 ,  14  or horizontal member  16 ,  18  may be formed of a solid material having a geometric profile substantially similar to that previously described herein in reference to the tubular embodiment of the vertical members  12 ,  14  and horizontal members  16 ,  18 . 
   In an embodiment of the invention, the means of fixing the location of each of the respective horizontal members  16 ,  18  with respect to the vertical members  12 ,  14  comprises a set of clamps that includes an upper clamp  30  and a lower clamp  32  for each end of each respective horizontal member  16 ,  18 , whereby each unsupported span  10  includes four sets of clamps for fixing the positions of the horizontal members  16 ,  18 . Each of the respective clamps  30 ,  32  is adapted to be removably mounted around a vertical member  12 ,  14  using a compressive force applied by the clamps  30 ,  32  when manipulated by a user. The compressive force is distributed to the outer periphery  34  of each of the respective vertical members  12 ,  14  to which each respective clamp  30 , 32  is affixed, thereby fixing the location of each respective clamp  30 ,  32  when the compressive force is applied. 
   In an embodiment of the invention, each of the respective upper and lower clamps  30 ,  32  are formed such that each clamp  30 ,  32  has a sufficient size such that the larger size of the clamps  30 ,  32  in relation to the hole  28  passing through each respective horizontal member  16 ,  18  operates to prevent each respective horizontal member  16 ,  18  from achieving vertical displacement with respect to each respective vertical member  12 ,  14  once the upper clamps and lower clamps  32  have been affixed to each respective vertical member  12 ,  14  in a position that abuts each respective horizontal member  16 ,  18 . 
   The tensioning member  20  is a flexible member having a first end including an associated first attachment  36 ; a second end including an associated second attachment  38 ; a length L; and a tensioning assembly  40  that may be manipulated by a user to induce stress in the tension member  20 . It is contemplated that the tension member  20  may be a strap, band, or cord formed of a woven or twisted material including, but not limited to: synthetic fibers or organic fibers such as cotton. 
   In an embodiment of the invention, the tension assembly  40  may include a ratcheting assembly  42  adapted to receive the tensioning member  20  and induce tension thereto between each of the first end  44  and the second end  46  by effectively reducing the length L of the tension member between each of the respective first and second ends  44 ,  46 . The material forming the tensioning member  20  has an inherent elasticity, and creates tension by the resistance of the material to the elongation caused by the effective decrease in length L. Additionally, it is contemplated that other means of inducing tension in the tensioning member  20  may be provided, including, but not limited to: a binding device or twisting device. 
   In an embodiment of the invention, the means for fixing the location of the tensioning member  20  may comprise an adapter such as a strap-to-chain adapter  48  as disclosed in U.S. Pat. No. 5,762,455, issued in the name of long and incorporated herein by reference. The strap-to-chain adapter  48  is comprised of a tether aperture  50 , an arcuate edge wall  52 , a tensioning aperture  54 , and an attachment aperture  56  where the tether aperture  50  is further defined by a tension bar  58  at each end of the tether aperture  50  and where the tether aperture  50  is defined as being substantially rectangularly elongated. The tensioning member  20  pulls against an edge that is integrally connected to the tensioning aperture  54  and further helps to define the tensioning aperture  54 . 
   In another embodiment of the invention, the means for fixing the location of the tensioning member  20  may comprise a ring or loop (not shown) formed of a rigid material, placed onto each respective vertical member  12 ,  14  in the same manner as the strap-to-chain adapter  48  of the previous embodiment. The ring or loop may be formed of materials including, but not limited to: wire, wire rope, cord, webbing, metal, and plastic. 
   In another embodiment of the invention, it is contemplated that the associated first and second attachments  36 ,  38  of the tensioning member may be adapted to directly attach to each respective first and second vertical member  12 ,  14 , and may be further adapted to receive a plurality of tethers  24 . 
   In an embodiment of the invention, each of the plurality of tethers  24  may comprise a predefined length of cord having a first end  45  and a second end  47 . The first end  45  of the cord may be affixed to the strap-to-chain adapter  48  by a suitable form of connection including, but not limited to: knots and crimped or spliced loops. The second end  47  of the cord may be affixed to one of the plurality of anchors  26 . The cord may be formed from materials including, but not limited to: rope, twine, webbing, bands, wire, and wire rope. 
   In another embodiment of the invention, each of the plurality of tethers  24  is formed of a planar band (not shown), having an associated width W that is proportionally larger than an associated thickness T, and is formed of a solid material including, but not limited to metal. Additionally, it is contemplated that the plurality of tethers  24  may comprise link chains of varying sizes and formed of a variety of materials including, but not limited to metal. 
   In an embodiment of the invention, the plurality of anchors  26  may be screw anchors  60 , as illustrated in  FIG. 5 . The screw anchor  60  may be formed from a predefined length of a solid material. The solid material is formed in the shape of a helical thread  62 , whereby the anchor may be fixed in a desired location by a user turning the screw anchor  60  such that the helical thread  62  engages the ground and draws the screw anchor  60  deeper into the ground with each successive turn until the screw anchor  60  reaches a depth desired by a user. An upper loop  64  is also formed on the screw anchor  60  such that a user may affix a tether  24  to the screw anchor  60 . 
   In another embodiment of the invention, it is contemplated that the each of the plurality of anchors  26  may be a stake (not shown) having a first end; a second end; a length L; a loop or other means of retaining a cord formed at the first end for affixing a cord thereto; and a sharp point formed at the second end for being pushed or driven into the ground. 
   A method of use is also provided wherein a user assembles and erects an unsupported span  10  by completing the following steps. First, a user passes a first end  44  of a first vertical member  12  through an upper clamp  30 . A user then passes a first end  44  of a second vertical member  14  through an upper clamp  30 . A user then passes the first end  44  of the first vertical member  12  through a first hole  28  passing through a first end  44  of a upper horizontal member  16 . The first end  44  of the second vertical member  14  is then passed through a second hole  28  passing through the second end  46  of the upper horizontal member  16 . The first end  44  of the first vertical member  12  is then passed through a lower clamp  32  and the first end  44  of the second vertical member  14  is then passed through a lower clamp  32 . 
   Each of the respective associated upper and lower clamps  30 ,  32  and the upper horizontal member  16  are placed in the position desired by the user. The user then tightens each of the respective upper and lower clamps  30 ,  32  thereby fixing the position of the upper horizontal member  16  with respect to the first and second vertical members  12 ,  14 . 
   A user then passes the first end  44  of the first vertical member  12  through a first strap-to-chain adapter  48  and the first end of the second vertical member  14  through a second strap-to-chain adapter  48 . 
   The first end  44  of the first vertical member  12  is then passed through an upper clamp  30  and first end  44  of the second vertical member  14  is passed through an upper clamp  30 . The first end  44  of the first vertical member  12  is then passed through a first hole  28  passing through a first end  44  of a lower horizontal member  18  and the first end  44  of the second vertical member  14  is then passed through a second hole  28  passing through a second end  46  of the lower horizontal member  18 . Each of the respective first ends  44  of the first and second vertical members  12 ,  14  is then passed through a respective lower clamp  32 . 
   Each of the respective associated upper and lower clamps  30 ,  32  and the lower horizontal member  18  are placed in the position desired by the user. The user then tightens each of the respective upper and lower clamps  30 ,  32 , thereby fixing the position of the lower horizontal member  18  with respect to the first and second vertical members  12 ,  14 . 
   The tensioning member  20  is then affixed to each of the first and second strap-to-chain adapters  48  by the first and second attachments  36 ,  38  of the tensioning member. The user then manipulates a tensioning assembly  40 , thereby creating tension in the tensioning member  20  and causing the unsupported span  10  to become rigid. 
   The assembled unsupported span  10  is then placed in a vertical orientation with respect to the ground with the each of the respective second ends  46  of the first and second vertical members  12 ,  14  being placed in mechanical contact with the ground. Optionally, the respective second ends  46  of the first and second vertical members  12 ,  14  may be driven into the ground. 
   A plurality of anchors  26  is then oriented at a plurality of locations desired by the user. Each of the plurality of tethers  24  is then affixed to the plurality of anchors  26 , thereby providing lateral support to the unsupported span  10 . 
   While several aspects have been presented in the foregoing detailed description, it should be understood that a vast number of variations exist and these aspects are merely an example, and it is not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the foregoing detailed description provides those of ordinary skill in the art with a convenient guide for implementing a desired aspect of the invention and various changes can be made in the function and arrangements of the aspects of the technology without departing from the spirit and scope of the appended claims.

Summary:
An unsupported span device for portable structures and portable signage is provided comprising a plurality of vertical members that provide vertical load-bearing capability to the unsupported span; a plurality of horizontal members for providing a bearing surface for a load applied to the unsupported span; means for fixing the location of the plurality of horizontal members with respect to the plurality of vertical members; a tensioning member for inducing tension between the plurality of vertical members; means for fixing the location of the tensioning member with respect to plurality of vertical members; a plurality of tethers for laterally stabilizing the unsupported span; and a plurality of anchors for providing fixed points of attachment for the plurality of tethers. A method of forming an unsupported span is also provided.