Abstract:
A containment structure with three sides and a triangular end is collapsible to a significantly smaller profile for ease in storage and transportation, yet keeps all major sections connected. Unique means of folds and hinging provide these advantages. Special applications (oriented upright or lying horizontal) from cleanup of lawn debris to emergency shelter of personnel and instruments can utilize the compact storage, ease of transport, quick setup, and shape advantages of the containment structure.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The current invention relates to a special collapsible, foldable, containment structure that has certain advantages in the areas of handling of loose materials, removal of debris and temporary, lightweight shelter of personnel, animals or equipment 
         [0003]    2. Description of Prior Art 
         [0004]    There are a number of special and important uses for a basic containment structure of triangular cross-section that is collapsible to a reduced profile for storage and transportation. For applications where the collapsible containment structure is used for containment of loose material, obvious uses are in industrial portage, construction cleanup and yard debris collection and removal. Examples of early box-like structures of triangular cross-section were U.S. Pat. Nos. 443,397 by Mack, 1,1933,643 by Tanner and 2,349,589 by Harrington. These were not quite in the patent class of the current invention. The structures were specifically of thin materials like cardboard, had fold lines to assist collapse (but none to further reduce the profile beyond flattened collapse or blanks) and had no hinges (necessary for any significant wall thickness). Class and subclasses  220 / 6  and  220 / 7  properly cover the collapsible containment structure of the current invention, but even before U.S. Pat. No. 3,759,412 by Bush and U.S. Pat. No. 3,966,072 by Gonzales, both in this class, the emphasis on rectangular, box-like collapsible containers overlooked the unique advantages of those with triangular cross section. To explain continuing needs and relevant prior art, one must reach outside the class for the current invention and consider what problems it can address. French patent 2618050(A1) by Desbrosse in 1989 specifies a box suitable for cat hygiene, but collapsibility to a profile less than the base, triangular profile, and hinges are not covered. A “Universal handling container” invention by Thomas Boyer, et. al., Jun. 11, 2002, U.S. Pat. No. 6,401,930 concentrates on electro-static discharge protection and does not afford the advantages of collapsibility cited by the current invention. A number of U.S. Pat. Nos. 4,006,928; 4,193,157; 4,318,521; 4,548,372; 4,572,559; 4,884,603; 5,498,046; 5,857,722; 5,915,768; 6,149,303; 6,450,461 and 7,744,044 all relate to shaping a floppy yard bag&#39;s entrance and sometimes the interior so it can be laid flat on the ground and yard debris swept into it. This is obviously different from the current invention where a flat side shape is a part of the containment structure itself without any insertion. Disadvantages of the cited patents are that they describe a floppy bag with the inconvenience of inserting and attaching another system into it. In damp weather the inserts tend to stick and are difficult to remove after use. Another inconvenience is that the entrance is limited by what the yard bag can accommodate: Using a wide yard broom to sweep debris into an entrance not much wider than the broom is obviously somewhat clumsy and requires many repeated movements for satisfactory filling. A “collapsible refuse collection apparatus” is described in U.S. Pat. No. 6,874,797 B2. It is made of flexible material with a framework and this differs from the current invention. To bag debris for waste pickup, a slightly stiff paper yard bag is inserted into it and it is laid down flat for sweeping into. It suffers the same restriction that other solutions do in that the area swept into is limited by the bag opening size. The said apparatus collapses, but no surface is folded more than once, unlike the current invention. Recognizing these problems may the basis of solutions with U.S. Pat. Nos. 5,104,133 and 5,529,321 where a large sheet of material like a tarpaulin is loaded with leaves or other debris and pulled away. In practice loading can be done by sweeping, but is often done by power air blowers driving the leaves onto the large surface. If done by a sizable commercial lawn care company, such a sheet may be folded and lifted by several people and then dumped into a truck bed for hauling away. When done by a smaller entity or home residents, bagging in standard yard bags for pickup by a waste management company is more appropriate, and thus the aforementioned large sheets offer no advantage. Smaller of the aforementioned sheets have been commercialized, some flexible and some with stiffness. In either case, personnel must frequently crouch or bend downward to close the bundle then rise and transfer it to an upright debris container. This is tiresome and limits efficient cleanup. The yard debris cleanup and handling is very similar to removal of construction debris or handling of loose materials in industrial sites. The omission of foldable, collapsible containers with triangular cross-sections and substantially rigid walls requiring hinges has continued through 2010 and is typified by U.S. Pat. No. 7,823,739 B2 by Sadkin, whose invention is in the same class and subclass as the current invention. 
         [0005]    Following Hurricane Katrina and the New Orleans disaster, plans were proposed by empathetic and entrepreneurial parties to accelerate movement of large populations into temporary housing faster than FEMA trailers could be provided. Tent cities were the unsatisfactory default alternative. Temporary shelter based on ship/railway shipping containers was proposed, but the incompleteness and non-collapsibility for transport carriers was a problem. The conclusion of such hurricane relief proposal studies is the need for a temporary receptacle or basic structure, better than a tent but less than a static building structure that could be collapsed, transported and easily erected for attachment of other personal-need equipment. The US patent class for “receptacle” allows such uses but overlaps other classes better explored through application terms than formal patent class terms. Application terms relating to temporary shelter, but less than static building components, were sought in the current patent search. Tents have been described in such patents as that by T. M. Wan (U.S. Pat. No. 5,411,046) but do not have the stiff surface wall segments to which utilities could be attached and they have an extra framework to contend with. U.S. Pat. No. 3,971,185 granted to J. H. Hendrich titled “Method of erecting a foldable building module” includes a foldable A-frame structure which, however does not include flooring (a 3 rd  side in the current invention) and collapses, but does not fold to a dimension less than one side of the roof. H. E. Walmer describes a dollhouse in U.S. Pat. No. 4,021,960. This structure is too complex and does not collapse to a small profile, thus transportability and simplicity for a scale-up is problematic. T. Dunn&#39;s U.S. Pat. No. 4,195,593 describes a dog house. It has extra framework in addition to wall structure and is sizable in profile when collapsed. It does not have the advantages of the current invention. G. A. Binkert was awarded U.S. Pat. No. 4,576,116 for a “Collapsible house for cats”. This falls into an insufficient category like tents, having even less advantages when scaled up. Japan patent 5209436(A) awarded to Nakatani specifies some degree of collapse using hinges, but does not fold to a small profile or have triangular cross section. U.S. Pat. No. 5,444,944 describes a “Low cost collapsible enclosure” which again basically has four erect walls with straightforward hinging, unlike the current invention. Its cost and complexity certainly exceed a simple a temporary shelter setup. J. Sung describes a “collapsible/foldable container” in U.S. Pat. No. 5,492,269. Its shape approaches octagonal at the entrance and because of numerous facets would not provide basic stability needed by light structure walled housing even if scaled up. The purpose of a “Collapsible shipping container” by R. J. Lickton in U.S. Pat. No. 6,039,243 appears to be a two-wheeled cart of triangular cross section that can be operated by one person. It is collapsible, but its profile is limited by not being smaller than one side, when opened. A patent search for emergency housing revealed that W. Koneke, in U.S. Pat. No. 5,752,470 proposed a “Collapsible structure” or small free-standing structure which generally assumed a rectangular shape after setup. His concept, on a larger scale, could be used for emergency housing. However, his invention is different from the tri-sided shape being described in the current invention and thus does not have its rigidity and resistance to deformation upon external pressure. It also does not reduce the area of the collapsed structure to less than that of one side of the expanded structure; in some cases it is greater. A patent search in “temporary housing” revealed U.S. Pat. No. 6,148,835 entitled “Temporary housing frame” by S. D. Rhee. However, his patent only concerned the house frame, which in some cases appeared to be collapsible. Still, a solution for collapse of the entire structure was not presented, as it is in the current invention. A “Collapsible container” by B. D. Blaszak in U.S. Pat. No. 6,698,382 B1 describes a structure which has three rectangular sides as does the current invention. However, it does not collapse to a profile width less than that of one side. Also, some folding is required in his finished structure and multiple layers upon folding sides with ends tucked inward requires unique hinging not described in his patent. Unless the wall thickness is very small (such as in a cardboard box), full collapse of the container is dysfunctional without further invention. U.S. Pat. No. 7,552,563 B2 issued to Becker has a remarkably folded structure for large enough housing and is classified by the USPTO as Static Building  52 . It differs from the current invention in that his structure is geometrically more complex, has more sides, must finally be fixed with means involving glue, nails, staples, tabs, etc., and has hinges which actuate rotationally in only one direction. Disadvantages for fast, temporary setup and tear down are the additional time and effort to deal with more complex folds, need to add and remove fastening means or deal with troublesome tabs and more fragility to external forces than the temporary, three-sided structure of the current invention. A U.S. Pat. No. 7,647,731 B2 titled “Prefabricated modular building” by inventor Muir describes a three-walled structure with separate room, appearing to be a semi-outdoor environment component. There the emphasis is on trusses for erect walls, does not have the advantage of simplicity and would require exterior cladding, unlike the current invention. Finally U.S. Pat. No. 7,631,460 B2 issued to Napier called “Transportable building” specifies a significant structure for housing that, although transportable to a site, is meant to be a static, complex building. The cost of such a structure in fabrication, transportation, erection and finishing would exceed the budget for of quick, simple emergency housing applications addressed by the current invention. 
       SUMMARY 
     Objects and Advantages 
       [0006]    One object of the current invention is a containment structure with a shape that has advantages for certain uses, examples to follow. Another object is the structural folding for collapse in a way that gives a uniquely small profile. A third object is utility from hinging methods uniquely affixed so as to accommodate the extra folds and keep structural segments connected. Specifically the advantages are: 1. Compact storage and transportability; every surface facet folds one or more times for a smaller profile, a degree unusual in collapsible containers. For example, on the smaller scale, a yard pickup container could be folded compactly and placed inside a narrower container for storage. Practically all pieces of the containment structure remain connected when collapsed. On the larger scale, a truck trailer bed could haul a stack of collapsed structures of width that, unfolded, would be oversized loads. 2. Wall stiffness requires some thickness, and for the benefits of increased folding with finite thickness, an unusual combination of hinging is provided to accommodate the requirements caused by the triangular cross-section. The current invention describes examples of at least three types of such hinging: ordinary bonded strip hinging, guided elastic strap hinging, and rotatable hinging for end segment(s). 3. The tri-sided shape of the structure itself affords benefits such as resistance to deformation and distortion by external forces. Other gains depend on use. For example, on the smaller scale, its shape contributes to reducing exhaustion in yard or construction site debris cleanup. As shown in  FIG. 7   a , the shape facilitates efficient sweeping into the broad containment structure when laying flat on its side (top), especially if the upward corner length  2   e  is slightly shorter than others  2   d  to allow a slope back of the opening for better visibility. Later ( FIG. 7   b ), it requires no significant stooping to reach down to the top side and lift the containment structure up and flip it over to dump it into a second container  13  from the opening&#39;s narrower region (apex region opposite the flat side over which it was filled). An advantage of this easy maneuver is that it would enable filling a yard bag with small or moderate opening in the second container by funneling debris from the larger containment structure through the narrow region near the intersection of its two sides. On the larger scale, the 3-side shape lying on its side ( 2   z  touching ground in  FIG. 1 ) is useful for temporary shelter of equipment or personnel ( FIG. 8 ). 
     
    
     
       DRAWING FIGURES 
         [0007]      FIG. 1 : Illustration and labeling of the surfaces bounding the volume of the collapsible containment structure. 
           [0008]      FIG. 2 : Relationship of lengths connecting vertices of opened structure volume. Side surfaces are depicted as transparent for internal visibility. 
           [0009]      FIG. 3   a : Fold line groups ( 3  and  4 ) in surfaces of collapsible containment structure; side surfaces are depicted as transparent for internal visibility. 
           [0010]      FIG. 3   b : Continuous hinging strips seen on surface  1   b  and side  2   y  for groups  3  and  4  fold lines and three edges (corners) of side surfaces. 
           [0011]      FIGS. 4   a  to  4   d : Progressive views through open end for successive stages of simultaneous collapse about group  3  fold lines and group  2  side edges. 
           [0012]      FIG. 4   e : Detail of underside of surface  2   z  as shown in  FIG. 4   a.    
           [0013]      FIG. 4   f : Alternate detail for underside of surface  2   z  as shown in  FIG. 4   a.    
           [0014]      FIGS. 5   a  to  5   d : Progressive views from side of collapsible containment structure showing folding process including end surface  1   b.    
           [0015]      FIG. 6 : Restraining means to avoid partial outfolding and collapse of end wall (surface  1   b ). 
           [0016]      FIGS. 7   a  to  7   b : Two-step process illustrating advantages of collapsible containment structure&#39;s shape for debris cleanup;  7   a —sweeping into containment structure,  7   b —flipping over and pouring from containment structure into container  13  of smaller diameter. (Preferably length  2   e  is slightly less than length  2   d ; fold lines are not shown.) 
           [0017]      FIG. 8 : Example of collapsible containment structure used for temporary or movable shelter; fold lines are not shown. 
       
    
    
     DESCRIPTION 
       [0018]    A solid geometry description of the opened structure is shown in  FIG. 1 : The empty volume is bounded by a five-surfaced area with triangular top and bottom ( 1   t ,  1   b ) and three side surfaces  2   x ,  2   y ,  2   z , said side surfaces each being 4-sided (or edged) polygons with two side edges substantially parallel. Surface segments have sufficient stiffness to maintain shape, as there is no other basic framework. Presently, the top surface ( 1   t ) of said structure is open and immaterial, its only purpose being to aid defining structure volume. In the preferred embodiment, the bottom edges of the sides are substantially perpendicular to the vertical edges. (When the top edges of the sides are also perpendicular to the vertical side edges, the volume is a special case known as a polyhedron with triangular cross-section. That restriction is optional as there is sometimes merit in a sloped top surface.) 
         [0019]      FIG. 2  depicts the relationship of lengths connecting certain vertices of the opened structure volume. A set of corresponding edge pairs of the top and bottom triangles are substantially equal in length ( 1   c ), but the other pairs of top and bottom triangle edges are lengths  1   a  and  1   d  which are equal only if length  2   e  is equal to length  2   d . The triangle formed by pair of edges of length  1   a  and edge of length  1   c  (at the top) project orthographically downward and coincide with the triangle formed by pair of edges with length  1   d  and edge of length  1   c  at the bottom. 
         [0020]      FIG. 3   a  depicts fold lines in the each of the material surfaces for the collapsible structure. Orientation is the same as in  FIG. 1 . The side fold lines (group  3 ) indicate whether a fold collapses inward (i) toward the vertical axis of the volume or outward (o) away from it. The bottom fold lines (group  4 ) also indicate whether a fold is ultimately collapsed inward (i) toward said vertical axis or collapses oppositely (o). The inward (i) fold lines are perforated to distinguish from (o) fold lines. Edges of surfaces not labeled in  FIG. 3   a  also have a folding collapse or a separation as will be discussed later. 
         [0021]    Although  FIGS. 1-3   a  depict a certain orientation where “top”, “bottom”, “vertical”, etc. have meaning in those illustrations for defining shape, they do not permanently define orientation or name walls of the structure which will be referred to as “end” and “sides.” 
         [0022]      FIG. 3   b  illustrates attached, flexible strips that allow hinging about certain fold lines and surface edges. Obviously, for thin malleable material like cardboard, a fold line can simply be a crease in the material which compresses its thickness along a line. For thicker, stiffer materials, this is insufficient. A preferred method is use of continuous strips bonded to the inside or outside of a surface at a fold line. In  FIG. 3   b , the containment structure is oriented for visibility of end surface  1   b  and side  2   y  as defined in  FIG. 1 . For sides, there are two flexible strips  3   h  that bond to the outside over fold lines  3   x  and  3   y  as defined in  FIG. 3   a . This allows inward collapse during folding. There are three strips (group  2   h ) bonded to the inside where side edges meet at an angle and allow angular decrease during collapse. The strips  2   h  are drawn with dashed lines. The downward side ( 2   z  in  FIG. 1 ) is a special case and is discussed later. The fold lines in the end surface  1   b  (facing observer) are bonded on the outside by two strips  4   h (i) allowing inward bending and bonded on the inside by strips  4   h (o) allowing outward bending. Strips bonded to the inside surface are again drawn with dashed lines. Naturally, a series of parallel metal hinges along the fold lines and surface edges or long piano hinges could accomplish the same results, and will also be referred to as “strip hinging”, but the preferred method of flexible strips is more pragmatic. Fold lines and outside edges on surface  1   b  and their interaction with side surfaces is discussed later. 
         [0023]      FIG. 4   a  shows an end view of the structure, looking through the open end with side surface  2   z  (in  FIG. 1 ) laying downward. Side edges  2   a  to  2   c  and fold lines  3   x ,  3   y ,  3   z  are shown.  FIGS. 4   b  through  4   d  depict stages of collapse of the sides about group  3  fold lines and edges  2   a  to  2   c . As indicated in the last paragraph, the hinge strips for both  3   x ,  3   y  fold lines is applied on the outside surface, and for  2   a  through  2   c  edges it is applied to the inside surface. The hinge strip for fold line  3   z  on surface  2   z  is different in that some disjointing of surface  2   z  is necessary as depicted in the last stages  FIGS. 4   c  and  4   d . The allowance for disjointing is accomplished by long elastic straps  6   a  oriented left to right in  FIG. 4   e.    
         [0024]      FIG. 4   e  depicts the undersurface (for the orientation in  FIG. 4   a ). It shows how elastic straps  5   a  pass through low-set guide loops  5   b  for alignment of segments of side surface  2   z . The tensile nature of elasticity provides closing for segments of surface  2   z  when it is laying out flat. The means for elasticity is easily represented by any variation of long, narrow metal or plastic springs, synthetic rubber bands, stretchy tie-down cords or bungee cords. We shall define elastic strap as meaning any and all such means. The ends of each elastic strap ( 5   c ) are fastened firmly to surface  2   z  near its outer edge. Adhesive bonding, heat fusion, riveting, and screwing are a few of the available means to do that. Obviously the whole strap device can be located in a left-to-right recession groove in the wall thickness of side surface  2   z , or elevated strips of surface material parallel to the strap direction could be placed on either side of the strap region. This would decrease interference of any adjacent external surface with the low guide loops or the strap material movement. To aid uniform strap stretching, the  2   z  surface just underneath the strap region would be treated or laminated for a very slick, low-friction material. Two of a group of hinges  6  for connecting surface  2   z  to surface  1   b  are shown and discussed later.  FIG. 4   f  depicts an alternate, but less preferred attachment of flexible, stretchable strip hinge material ( 5   d ) over fold line  3   z  (o). For walls of any significant thickness, there is considerable stress on the hinge material upon folding because of its lesser width, especially if it is on the surface  2   z  which faces downward in  FIG. 4   e . Of course, the separable fold need not have any elastic material connecting the two parts of side surface  2   z , if extra effort is applied to setup, collapse and fastening of the sections together when the structure is open. 
         [0025]      FIGS. 5   a - 5   d  depicts a succession of side views toward the  2   y  side as the containment structure is collapsed. It shows how the end surface  1   b  folds outward at fold lines  4 ( o ) and inward at fold lines  4 ( i ). Six special hinges  6  near the end-edge of side surfaces are located close to group  3  fold lines and connect on either side of inward folds  4 ( i ) on surface  1   b . This allows partial separation of end surface  1   b  from the adjacent edges of side surfaces  2   x ,  2   y ,  2   z  without being completely disconnected. This is necessary because (as shown in  FIG. 5   b ) end surface  1   b  must contort through an intermediate position in collapsing where continuous contact along all edges of surface  1   b  and the side surfaces  2   x ,  2   y ,  2   z  is not possible. This separation is most prominent near the three corners of the triangular end piece. A necessary property of the hinges  6  is that they fold from a right angle connecting surface  1   b  and sides  2   x ,  2   y ,  2   x  when the containment structure is fully open to a flat, extended open position when fully collapsed ( FIGS. 5   c  and  5   d ). Another property making them unique is that each hinge must swivel slightly about an axis perpendicular to one surface to which it is connected. This may be accomplished most simply by at least one single rotatable fastening of the hinge to one of the connected surfaces (preferred) or else a very elastic hinge material. Another feature of  FIG. 5   a  is three braces  7  each having a groove that forms a u-shaped cross section. The brace is mounted on the end edge of walls for side surfaces  2   x ,  2   y ,  2   z . The open groove of the brace is very nearly the same width as the side wall material thickness, and is pressed over it for the fully opened containment structure. The length is sufficient to stiffen and align walls for contacting side sections  2   x ,  2   y ,  2   z  in the region of group  3  fold lines. The braces&#39; midpoints are substantially over the ends of group  3  fold lines. To keep them attached to the structure side walls, they are hinged at one end so they can be rotated back for structure folding and collapsed without detaching.  FIG. 5   b  shows the brace rotated away from the fold line  3   y.    
         [0026]      FIG. 6  illustrates the means to keep end surface  1   b  from pushing outward and causing an unwanted partial collapse of the opened structure. The solid lines shown in the interior of end surface  1   b  depict outward folding surfaces. Side surface  2   z  is downward in this orientation. Only end edges of side surfaces  2   x  and  2   y  are seen. A flat bar  8   a  riveted into the end of one of said side surfaces near the top has a notch in the other end and swivels down to latch over the neck of a stud mounted in the end thickness of the adjacent side. The rivet (or nut and bolt) keeps the small bar from being lost when the containment structure is collapsed. A larger flat bar  8   b  lower down has notches at both ends and latches over the neck of two studs mounted lower in the end thickness of the same side surfaces. For stowage when collapsed, bar  8   b  can be removed and slid underneath one or more of the elastic straps in group  5   a  (see  FIG. 4   b ). 
       CONCLUSIONS, RAMIFICATIONS AND SCOPE 
       [0027]    The current invention provides a unique combination of simple structures and folding means. It avails itself to several receptacle functions in ways that reduce storage and transport problems, task labor, expense, time and exhaustion. The invention&#39;s relatively rigid wall segments with triangular and rectangular geometries provide unique advantages. However they also require a varied combination of hinging devices to accommodate folding and collapse to an unusually small profile while yet maintaining connection. Surprising and difficult fold dynamics that occurred in the prototype were remedied and the results became a part of this application. 
         [0028]    The flexible strip hinging for several fold lines were presented in examples as bonded to a side or end surface wall over a fold line, either externally or internally. As explained, this strip could be replaced by a series of small hinges in a line, each closing in a direction perpendicular that line, and serve the same purpose. Also a flexible hinge strip could be replaced by a “living hinge”, a thinner molded part of the connecting wall segments. Depending on use, weather stripping or available similar means at fold lines and the junctions of side and end walls may be affixed to avoid air, moisture, gas or liquid penetration. For example a gasket-like function could be attained by placing such stripping on the interior very near the adjacent edges of side and end walls. If on the interior of both side and end walls, compression of the two malleable strips could occur. Due to elasticity of such stripping, required hinging should not present a problem. An overall, close fitting bag-like covering could also be slipped on, as an option for weatherproofing. 
         [0029]    The current invention has not heretofore specified all appropriate receptacle contents, living or inert; it has presented examples to show utility. It has not specified a particular second end surface (top  1   t  in  FIG. 1  and opposite from the side facing reader in  FIG. 6 ). For secure contents access or temporary shelter use, entrance details are extremely application dependent. One option is to make a surface cover for it connect and operate in exactly the same way as does the rear (or bottom) having surface  1   b  ( FIGS. 3   b  and  5   a ). A surface segment may be removed or a hole simply cut into the front to allow entrance. However, a second end for  1   t  could be a separate front surface connected with screws, clamps or other usual fasteners.  FIG. 8  shows that for temporary or mobile personnel containment, ducting, storage or lighting may be fastened to the upper apex region  9 , and low desks  10 , equipment storage  11 , or bunk  12  could be placed in the lower side corners where there is less room for standing or sitting. In an emergency response, such a structure could be mounted on the bed of a truck. It could provide mobile weather protection for gear and personnel until permanent building structure is facilitated. 
         [0030]    The current invention does not specify particular material, but rather pertains to mechanics and fold structure dynamics. However, available materials for the side and end walls of the structure do exist. Examples are walls of lightweight solid wood, coated balsa, polymer foam panels bonded to thin sheets of durable plastic; metal, fiberglass or carbon honeycomb clad with solid sheeting, etc. Any durable material is usable, but the lighter materials with porous or structured voids are more portable. It is essential that the thickness of cladding or inner contents of the wall be of sufficient strength to support screws or adhesion for any attachments that are desired in the receptacle. 
         [0031]    Examples given illustrate advantages of the current invention but do not limit it. Reasonable extensions of specifications presented also fall within the scope of the current invention. The scope should be determined by appended claims and legal equivalents, rather than by examples given. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                   
               
               
                 References Cited 
               
               
                   
               
             
             
               
                 U.S. Patent Documents 
               
             
          
           
               
                   443,397 
                 December 1890 
                 Mack 
                 NA 
               
               
                 1,933,643 
                 November 1933 
                 Tanner 
                 229/22 
               
               
                 2,349,589 
                 March 1942 
                 Harrington 
                 229/22 
               
               
                 3,759,412 
                 September 1973 
                 Bush 
                 220/7 
               
               
                 3.966,072 
                 June 1976 
                 Gonzales 
                 220/7 
               
               
                 3,971,185 
                 July 1976 
                 Hendrich 
                  52/745.14 
               
               
                 4,006,92 B 
                 February 1977 
                 Beugin 
                 294/1.1 
               
               
                 4,021,960 
                 May 1977 
                 Walmer 
                 446/104 
               
               
                 4,193,157 
                 March 1980 
                 Large 
                  15/257.1 
               
               
                 4,195,593 
                 April 1980 
                 Dunn 
                 119/499 
               
               
                 4,318,521 
                 March 1982 
                 Martin 
                 248/99 
               
               
                 4,548,327 
                 October 1985 
                 Lutzker 
                 248/99 
               
               
                 4,576,116 
                 March 1986 
                 Binkert 
                 119/498 
               
               
                 4,572,559 
                 February 1986 
                 Gainey 
                 294/1.1 
               
               
                 4,884,603 
                 December 1989 
                 Simpson 
                 141/390 
               
               
                 5,104,133 
                 April 1992 
                 Reiner 
                 280/19 
               
               
                 5,411,046 
                 May 1995 
                 Wan 
                 135/126 
               
               
                 5,444,944 
                 August 1995 
                 Roelofsz 
                 52/64 &amp; 52/79.5 
               
               
                 5,492,269 
                 February 1996 
                 Sung 
                 229/117.06 
               
               
                 5,498,046 
                 March 1996 
                 Ridley 
                 294/1.1 
               
               
                 5,529,321 
                 June 1996 
                 Thompson 
                 280/19 
               
               
                 5,752,470 
                 May 1998 
                 Koneke 
                 119/499 
               
               
                 5,857,722 
                 March 1996 
                 Ayotte 
                 294/1.1 
               
               
                 5,915,768 
                 June 1999 
                 Young 
                 294/1.1 
               
               
                 6,039,243 
                 March 2000 
                 Lickton 2 
                  29/117.01 
               
               
                 6,148,835 
                 November 2000 
                 Rhee 
                 135/145 
               
               
                 6,149,303 
                 November 2000 
                 Froehlich 
                 383/6 
               
               
                 6,450,461 
                 September 2000 
                 Lohmann 
                 248/99 
               
               
                 6,698,382 
                 March 2004 
                 Blaszak 
                 119/68 
               
               
                 7,552,563 B2 
                 June 2009 
                 Becker 
                  52/79.5 
               
               
                 7,647,731 B2 
                 January 2010 
                 Muir 
                  52/79.5 
               
               
                 7,744,044 
                 June 2010 
                 Gabriel 
                 248/101 
               
               
                 7,823,739 B2 
                 November 2010 
                 Sadkin 
                 220/6, 220/7 
               
             
          
           
               
                 Foreign patents cited 
               
             
          
           
               
                 FR 2618050 A1 
                 January 1989 
                 Desbrosse 
                 A01k1/01B5 
               
               
                 JP 5209436 A 
                 August 1993 
                 Nakatani 
                 E04B1/344