Abstract:
A modular sign stand. The preferred embodiment consists primarily of a base portion attached to a breakaway column. The base portion is intended to be driven into the ground. The breakaway column supports an attached sign. The breakaway column is pierced by one or more breakaway holes at a position just above the ground. When the sign stand is struck by a moving vehicle, the one or more breakaway holes cause the breakaway column to fracture in a predictable fashion near its attachment to the base. Several embodiments are disclosed, including one forming the breakaway column and the base as one integral unit.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of road signs. More specifically, the invention comprises a road sign stand having a specially designed base portion which allows it to break in a controlled fashion when struck by a vehicle. 
     2. Description of the Related Art 
     Roadside signs have been in common use for many decades. The use of portable signs to alert drivers as to construction zones and other hazards have become increasingly common. While these signs serve a useful purpose, they also present a hazard if struck. Accordingly, many prior art designs are configured to break away if struck by a moving vehicle. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention comprises a modular sign stand. It consists primarily of a base portion attached to a breakaway column. The base portion is intended to be driven into the ground. The breakaway column supports an attached sign. The breakaway column is pierced by one or more breakaway holes at a position just above the ground. When the sign stand is struck by a moving vehicle, the one or more breakaway holes cause the breakaway column to fracture in a predictable fashion near its attachment to the base. Several embodiments are disclosed, including one forming the breakaway column and the base as one integral unit. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is an isometric view, showing the proposed invention. 
     FIG. 2 is an isometric view, showing a typical sign. 
     FIG. 3 is an isometric view, showing the proposed invention installed. 
     FIG. 4 is an isometric exploded view, showing how the base attaches to the breakaway column. 
     FIG. 5 is an isometric detail view, showing the lower portions of the invention as installed. 
     FIG. 6 is an isometric detail view, showing the lower portions of the proposed invention after fracturing. 
    
    
     REFERENCE NUMERALS IN THE DRAWINGS 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 10 
                 sign stand 
                 12 
                 base 
               
               
                 14 
                 breakaway column 
                 16 
                 horizontal stay 
               
               
                 18 
                 vertical stay 
                 20 
                 stay pivot 
               
               
                 22 
                 stay anchor 
                 24 
                 point 
               
               
                 26 
                 breakaway hole 
                 28 
                 bolt 
               
               
                 30 
                 fin 
                 32 
                 sign 
               
               
                 34 
                 stay pocket 
                 36 
                 ground 
               
               
                 38 
                 bolt hole 
                 40 
                 nut 
               
               
                 42 
                 impact force 
                 44 
                 fracture 
               
               
                   
               
             
          
         
       
     
     DESCRIPTION OF THE INVENTION 
     FIG. 1 shows sign stand  10  in its assembled state. Base  12  is configured to be inserted into the ground. Its lowest extremity is provided with point  24 . Fin  30  extends out from the side of base  12 . When installed, the top of fin  30  is typically at or just below ground level. For installation purposes, a user can step on fin  30  and press base  12  into the ground. Where harder soil is encountered, the user can strike the upper portion of fin  30  with a hammer in order to drive base  12  into the ground. 
     Breakaway column  14  is attached to base  12  by bolts  28 . The use of bolts  28  is not particularly important to the invention. Many other types of fastening could be used—such as rivets, adhesives, or mechanical interlocking features. Breakaway column is tall and slender, extending from ground level as high as six feet or more. Features allowing the attachment of a sign are provided near its upper extreme. These are vertical stay  18  and horizontal stay  16 . Vertical stay  18  is typically attached to breakaway column  14  in a fixed position—as shown (via stay anchor  22 ). However, horizontal stay  16  is pivotally attached at stay pivot  20 . This feature allows horizontal stay  16  to be rotated 90 degrees so that it aligns with breakaway column  14  for convenient storage when the device is not in use. Many prior art methods can be used to attach the stays to breakaway column  14 , including bolts, rivets, adhesives, etc. 
     FIG. 2 shows a typical sign  32 . In this case, sign  32  is made of fabric mesh. It is attached to sign stand  10  by placing the tips of horizontal stay  16  and vertical stay  18  within the four stay pockets  34  on the rear side of sign  32 . The stays are made of flexible material so that the tips can be bent and placed within stay pockets  34 . If sign  32  is then appropriately sized, the stays will maintain tension on the fabric mesh, much like the structure of a kite. 
     FIG. 3 shows sign stand  10  installed in ground  36  with sign  32  attached. The reader will observe that the upper extreme of base  12  is roughly even with ground  36 . Breakaway column  14  extends upward from base  12  to mount sign  32 . The reader will observe that the lower portion of breakaway column  14  is pierced by two breakaway holes  26  (one through each wall of breakaway column  14 &#39;s L-shaped cross section). These features allow sign stand  10  to break in a predictable fashion, as will be explained shortly. 
     FIG. 4 shows details of how base  12  attaches to breakaway column  14 . Bolt holes  38  are provided in both base  12  and breakaway column  14 . Four bolts  28  and nuts  40  are used to lock the assembly together. The actual method of attachment is unimportant, so long as the lower extreme of breakaway column  14  is securely fastened to base  12 . 
     FIG. 5 shows the assembly installed in ground  36 . If, at this point, a vehicle strikes sign stand  10 , a substantial impact force is applied to breakaway column  14  (indicated as impact force  42 ). This force places a substantial bending moment on breakaway column  14 . Base  12  tends to resist this bending moment, since it is anchored in the ground. Fin  30  also tends to secure base  12  by providing additional surface area for soil contact. Thus, the portion of breakaway column  14  which is attached to base  12  tends to remain fixed, whereas the upper portion tends to flex upon impact. The result is a concentration of stress around the two breakaway holes  26 , since these features produce a considerably weakened cross section. 
     FIG. 6 shows the result. Breakaway column  14  has fractured (fracture  44 ) through the two breakaway holes  26 . This type of fracture occurs in a very controlled and predictable fashion. The placement of the two breakaway holes  26  force the fracture to occur just above ground level. The result is that breakaway column  14  bends over and passes safely under the vehicle striking the sign. No portion of breakaway column  14  passes over the vehicle (which would cause a hazard to the vehicle&#39;s occupants. 
     Material selection for the device is important. For best results (i.e., safest results), the material selected for breakaway column  14  should fracture without completely separating the two resulting sections. This action guarantees that the portion of breakaway stand  14  lying above fracture  44  will not become separated from the lower portion. Fracture  44  therefore acts like a hinge—it allows the column to fall over but will not allow it to tear free. If the column tore free, it could rotate upward and possibly strike the vehicle occupants. 
     Composite materials are particularly suitable for breakaway column  14 . They are stiff and light, yet are sufficiently brittle to fracture predictably when breakaway holes  26  are introduced. In addition, the existence of reinforcing fibers in the composite materials prevent the separation of the two fractured components after impact. Many fibers will span fracture  44 , holding the two pieces together. 
     Glass fiber reinforced plastics are effective in this application. Fiber orientation wilt of course, affect the fracture properties. Both a mat/roving fiber orientation and a unidirectional orientation (with the fibers aligned along the long axis of breakaway column  14 ) will work. Sample materials include glass reinforced ABS. Those sidled in the art will realize that many reinforcing fibers could be used other than glass. Glass is, however, generally very cost-effective. As high strength is not critical for this application, it is therefore a good choice. 
     Base  12  is ideally made of a tough material which can withstand extended use (including hammering). Steel, aluminum, or other metals are ideal for this component. An individual base  12  can be attached to a replacement breakaway column  14  if the original column is fractured. An individual base  12  can be used for many years. 
     Of course, those skilled in the art will know that breakaway column  14  and base  12  could be made as a single integral unit. Fin  30  then becomes simply another molded feature. However, because of the fact that fin  30  is subject to hammering, it is necessary to reinforce it with a tougher material—such as metal. A metal portion is ideally formed over the composite comprising fin  30 . Those skilled in the art will realize that because the desired material properties for the breakaway column and the base are in opposition (one must be tough whereas the other is ideally somewhat brittle), it is advantageous to form them separately. 
     Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiment of the invention. Thus, the scope of the invention should be fixed by the following claims, rather than by the examples given.