Abstract:
A collapsible projection backwall system utilizes a short throw projector and a collapsible framework to create a display usable in a small amount of space. The framework is specifically configured to support and appropriately position a flexible screen member so that distortion is avoided. This is particularly significant in situations where a relatively large screen is utilized, which creates the need to maintain appropriate tension upon the flexible screen member. The framework is specifically configured to be slightly canted when in its extended configuration to thereby introduce natural tension forces which will cooperate with the screen fabric to maintain the necessary configuration for the screen. This canted configuration is achieved by configuring a set of corner hinge assemblies and any central hinged assemblies to maintain this natural cant. By maintaining the desired forces on the display screen fabric a more efficient and functional display screen is created.

Description:
CROSS-REFERENCE TO RELATED CASES 
     This application claims the benefit of previously filed U.S. Provisional application 61/162,046, filed Mar. 20, 2009 and entitled “Projection Backwall Apparatus and System”. 
    
    
     BACKGROUND 
     Display exhibits and booths used at tradeshows and exhibitions are preferably easily transportable, are preferably quickly and easily erected and collapsed, and are preferably light weight for ease of portability and to reduce shipping costs. Additionally, the area available to each exhibitor at tradeshows and exhibitions is limited. Accordingly, exhibitors desire to maximize the limited space available to them. 
     A common feature used by exhibitors is a backwall, which may be a simple hanging curtain, or a series adjacent retractable banners such as disclosed in U.S. Pat. No. 7,337,567 issued to Skyline Displays, Inc., or self supporting frames or structures with fabric or rigid panels. The backwall serves two primary purposes. First, it provides a large prominent surface on which company logos, promotional materials and images of the company&#39;s products, services or other eye-catching images may be displayed to attract visitors to the exhibitor&#39;s display area. Second the backwall serves to conceal extra promotional materials, supplies, packaging, containers and other items that the exhibitor does not want visitors to be able to view or access. 
     The space available behind the backwall is generally very limited because tradeshow rules often require display backwalls to be no more than three feet from the facility&#39;s walls or other structures, so that one exhibitor&#39;s backwall does not block the display of neighboring exhibitors. In any event, exhibitor&#39;s typically want to have the backwall as far back as possible to provide adequate space in front of the backwall for tables, chairs and other furnishings on which to display promotional materials and to provide adequate free space to allow exhibitor representatives and visitors to easily move around to view the promotional items and to mingle and discuss business. 
     Many exhibitors desire to project images on the backwall of their display area, such as their company logo, or other eye-catching images to promote their products or services and to attract visitors to the display area. Until the relatively recent development and availability of short-throw, wide angle projectors, most exhibitors that wanted to project an image on a backwall of their booth or display, they had to use a conventional front projection system which required the projector to be placed toward the front of the display area or booth in order to produce a large image on the backwall. However, when placing the projector at the front of the display area, shadows would be produced blocking the projected image anytime someone walked between the projector and the backwall. 
     With the relatively recent development and commercial availability of short-throw, wide angle projectors, exhibitors are now able to place the short-throw projector within a few feet of the backwall while still producing a large image on the backwall, thus significantly reducing the chance that the projected image will be blocked by shadows from people walking between the projector and backwall. However, with such systems, the short-throw projector still takes up valuable space within the display area that could be used for other purpose. 
     Furthermore, although rear projection screens are known and although rear projection screens would overcome the foregoing disadvantages of a conventional front projection system as well as a short-throw front projection system, the use of rear projection systems at tradeshows or exhibitions has been uncommon and heretofore unpractical, at least for most exhibitors, due to the cost and difficulty of setup of rear projection systems to produce a distortion free image. It should be appreciated that in order to produce an image on a rear projection screen that is not distorted, the screen must be planar and must be uniformly stretched without any distortions. The need for planarity and lack of distortion is due to the unique optically transmissive and light diffusive characteristics of rear projection screens which permit the image to be viewed through the screen, as opposed to being reflected as with a front projection screens. 
     Accordingly, there is a need for a relatively inexpensive projection backwall for use at tradeshows, exhibitions, and the like, which is collapsible and relatively light weight for ease of portability and which is quickly and easily erectable and collapsible, and, when erected, results in a substantially planar and distortion free surface that is able to display substantially distortion free projected images. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a projection backwall system with an embodiment of projection screen and an embodiment of a short-throw, wide-angle projector. 
         FIG. 2  is a side elevation view of the projection backwall system of  FIG. 1  and illustrating an imaging being projected by the projector on the projection screen. 
         FIG. 3  is an exploded and enlarged perspective view of the corresponding area circled in  FIG. 1  illustrating a preferred method of assembling the corner and foot attachment for the projection screen frame. 
         FIG. 4  is an exploded perspective view of an embodiment of a frame corner hinge assembly. 
         FIG. 5  is a perspective view of the corner hinge assembly of  FIG. 4  shown assembled and secured to frame members in the fully open position and with the foot removed for clarity. 
         FIG. 6  is a perspective view of the corner assembly of  FIG. 5  in the partially folded position. 
         FIG. 7  is an exploded and enlarged perspective view of the corresponding area circled in  FIG. 1  illustrating an embodiment of a frame middle hinge assembly. 
         FIG. 8  is an exploded perspective view of the assembled frame middle hinge assembly of  FIG. 7 . 
         FIG. 9  is a perspective view of the middle hinge assembly of  FIG. 8  shown in the partially folded position. 
         FIG. 10  is an enlarged partial perspective view illustrating a preferred embodiment for attaching the stretch fabric to the frame and for spanning the corner hinge and middle hinge assemblies. 
         FIG. 11  is a schematic diagram illustrating the configuration of the frame (exaggerated for clarity) before the stretch fabric is applied which draws the angled hinged frame members inward resulting in substantially planar and distortion free projection screen. 
         FIGS. 12-20  illustrate how the projection backwall of  FIG. 1  may be erected and folded. 
         FIGS. 21 and 22  are enlarged partial perspective views illustrating another embodiment of the structure for attaching the stretch fabric to the frame. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIG. 1  is a perspective view of a preferred embodiment of a projection backwall system designated generally by reference numeral  10 . The projection backwall system  10 , comprises a projection screen  12  and preferably a short-throw, wide angle projector  14 , such as an NEC® WT Series mirror projector, which is capable of projecting a large image on a screen from a relatively close distance.  FIG. 2  is a side elevation view of the system  10  illustrated in  FIG. 1  showing the projector  14  projecting an image on the projection screen  12 . 
     It should be appreciated that although the projection backwall system  10  is particularly suited for tradeshows and similar events, the projection screen  12  may be used with conventional front projectors whether for in-home use, schools, business settings or for any other event where ease of screen setup and portability is desired, or if space is limited, the projection screen  12  may be used with short-throw, wide-angle front or rear projectors. 
     The projection screen  12  preferably comprises a stretch-fabric material  18 , such as Lycra®, that is preferably removably secured to a collapsible frame  20 . For rear projection applications, the stretch-fabric material  18  is preferably a translucent, high-density fabric suitable for short-throw, wide-angle rear projections. This same material may be suitable for front projection applications as well, or a material with more reflective characteristics may be equally or better suited. 
     The frame  20  preferably includes upper and lower horizontal frame members  22 ,  24 , and left and right vertical frame members  26 ,  28 . The frame members  22 ,  24 ,  26 ,  28  are preferably extruded tubular shapes, preferably of aluminum or other lightweight and suitably rigid material. The preferred cross-section of the extruded tubular shapes can be seen in  FIGS. 3 and 8 . 
     In the preferred embodiment, the upper and lower horizontal frame members  22 ,  24  preferably comprise a pair of horizontal members  22   a ,  22   b  and  24   a ,  24   b , respectively, which are connected at one end with a middle hinge assembly  32 . Similarly, the left and right vertical members  26 ,  28  preferably comprise a pair of vertical members  26   a ,  26   b  and  28   a ,  28   b , respectively, which are also connected at one end by a middle hinge assembly  32 . The horizontal and vertical frame members are preferably connected at their free ends by four corner hinge assemblies  30 , thereby forming a parallelogram-like configuration (discussed later). It should be appreciated that depending on the size of the projection screen  12  desired, the frame  20  may consist of more or fewer horizontal and vertical frame members. For example, if a smaller screen is desired, it may be suitable to use only four horizontal and vertical frame members joined by four corner hinge assemblies  30 , thus eliminating the need for the middle hinge assemblies  32 . Alternatively, if a larger screen is desired, three or more upper and lower horizontal members and two or more vertical frame members may be used, thereby requiring six, eight or more middle hinge assemblies  32 . 
     A pair of feet  34 ,  36 , are preferably removably secured to the frame  20 . The feet  34 ,  36  should be of sufficient length to laterally support the frame  20  so that it is stable and does not easily tip. It should be appreciated that the length of the feet may need to vary depending on the vertical height of the frame  20  to provide greater lateral stability. 
       FIG. 3  is an exploded perspective view illustrating a preferred embodiment for removably attaching the feet  34 ,  36  to the frame  20 . Although only one foot is discussed, it should be understood that the same description applies to each foot. The foot  36  preferably includes a pair of spaced slots  38  each slot having an enlarged lobe  40  to receive the heads  42  of pins  44 . The pins  44  are preferably fixed to the frame  20  by pop-rivets  46 , threaded fasteners or other suitably strong connection. In addition, a spring loaded pin  48  is included, which is attached to foot member  36 . Spring loaded pin  48  has a knob  49  attached at one end which allows for movement against the force of an internal spring (not shown). During mounting, knob  49  is pulled, causing pin  48  to withdraw so pins  44  can be coupled within slots  38 . Once approximately positioned, pin  48  will seat in hole  45 , thereby locking feet  36  in place. An alternative embodiment could use a flexible locking plate affixed to foot  36  having circular apertures to receive and lock with a related pin, or other locking mechanisms. As best illustrated in  FIG. 15 , in order to remove the foot  36 , the pin  48  is pulled back releasing the pin head  42  from the aperture  45  which allows the pins  44  to slide upwardly out of the slots  38  and the pin heads  42  to be pulled through the enlarged lobes  40 . 
     An exploded perspective view of the corner hinge assembly  30  is illustrated in  FIG. 4 . The corner hinge assembly  30  includes two hinge members  50 ,  51  which are pivotally connected by a pin  52  extending through mating offset ears  53 ,  54 ,  55 ,  56 . Each hinge member  50 ,  51  further includes an abutting face  57 ,  58  preferably sloped at approximately forty-five degrees (discussed later) so as to produce approximately a ninety degree corner when the frame  20  is unfolded. A leg  59  extends from each hinge member  50 ,  51 . Recesses  60  are disposed in each leg  59 . As best illustrated in  FIG. 3 , the legs  59  are preferably received within the frame members  22 ,  24 ,  26 ,  28  and secured by a threaded connector  62  ( FIG. 3 ) threaded into an aperture  64  in the frame member which engages the recess  60  to lock the legs  59  within the frame members.  FIGS. 5-6  illustrate how the corner hinge assemblies  30  pivot when moving from the open position  FIG. 5  to the partially folded position  FIG. 6 . 
     An exploded perspective view of the middle hinge assembly  32  is illustrated in  FIG. 7 . The middle hinge assembly  32  includes two hinge members  70 ,  71  which are pivotally connected by a pin  72  extending through mating offset ears  73 ,  74 ,  75 ,  76 . A leg  79  extends from each hinge member  70 ,  71 . The legs  79  are preferably received within the frame members  22 ,  24 ,  26 ,  28  and secured by a threaded connector  62  ( FIG. 8 ) threaded into an aperture  64  in the frame member and received by the recess  80  to lock the legs  79  within the frame members. 
     Each hinge member  70 ,  71  further includes offset opposing blocks  82 ,  84 . A locking pin  86  is slidably movable within a first bore  87  extending through the first block  82 . A knob  88  is threadably secured to one end of the pin  86  on the exterior of the hinge assembly  32 . The other end of the pin  86  includes a head  89  that is larger than the first bore  87 , such that with the knob  88  secured to the other end of the pin  86 , the pin cannot be pulled out of the first block  82 . The second block  84  includes a second bore  90  sized to receive the head  89  of the locking pin  86 . The second bore  90  is substantially coaxial with the first bore  87  when the hinge assembly  32  is assembled as shown in  FIG. 8 . Thus, it should be appreciated that by pushing on the knob  88 , the head  89  of the locking pin  86  slidably extends into the second bore  90  thereby locking the first and second hinge members  82 ,  84  together with the frame members in substantial longitudinal alignment. To unlock the hinge members thereby permitting the frame members to fold as illustrated in  FIGS. 9 and 11 , the knob  88  is pulled outwardly, thereby slidably withdrawing the head  89  from the second bore  90 . In the locked position, it should be appreciated that the transverse surfaces  92   a ,  92   b ,  94   a ,  94   b  of the respective opposing blocks  82 ,  84  abut one another. The abutting surfaces are preferably approximately perpendicular to a longitudinal axis for reasons which will be discussed in more detail later. 
       FIG. 10  illustrates a method of attaching the stretch-fabric screen  18  to the frame members  22 ,  24 ,  26 ,  28 . As illustrated, the stretch-fabric screen  18  preferably includes an outer peripheral flange  96  that is frictionally received within channels  98  extending along the length of the frame members  22 ,  24 ,  26 ,  28 . A break in the peripheral flange  96  is provided at each middle hinge assembly  32  and at each corner hinge assembly  30  as illustrated. The flange  96  is preferably comprised of a plurality of elongated rectangular flange members  99  secured to the stretch fabric  18 . The members  99  are preferably made of vinyl or other suitable material that it is lightweight, longitudinally flexible and resilient, yet somewhat rigid or stiff in the lateral direction. The stretch-fabric  18  may be secured to the flange members  99  by stitching, by adhesive, by providing pockets into which the flange members  99  are received or by any other suitable attaching method. As previously indicated, the flange sections  96  are frictionally received within the channels  98  so that the fabric screen  18  is securely yet removably secured to the frame  20 . 
       FIGS. 21 and 22  illustrate an alternative embodiment for attaching the stretch-fabric screen  18  to frame members  128   a  and  128   b . As shown, the stretch-fabric screen  18  includes a ridged peripheral flange  196  that is received within a mating channel  198  extending along the length of the frame members  128   a ,  128   b . As in the previous embodiment, the ridged peripheral flange  196  is preferably made of vinyl or other suitable material that it is lightweight, longitudinally flexible and resilient, yet somewhat rigid or stiff in the lateral direction. The ridged flange  196  includes a ridged flange member  199  which has outwardly projecting ribs  194  positioned a distance from the flange end  195 . The sidewalls  190  and  192  of the mating channel  198  include a mating recess  193  to receive the ribs  194 . It should be appreciated that the width of the opening of the mating channel  198  is greater than the width of the flange end  195  but less than the width of the outwardly projecting ribs  194  of the flange member  199  so as to create an interference fit. In use, the end portion  195  of the flange  196  is first inserted into the channels  198  temporarily holding the screen to the frame. The ridged flange  199  is then pressed into the mating recess  193  to securely seat the flange into the channel with an interference fit. 
       FIG. 11  provides an exaggerated illustration of a preferred configuration of the frame  12  prior to attaching the stretch fabric screen  18 . It should be appreciated that the greater the span between corner hinge assemblies and the tighter the stretch fabric  18  is stretched, the greater will be the tendency for the frame members to bow inwardly toward the middle of the span, resulting in the screen  18  being less taut toward the middle thereby distorting the projected image. To account for the bowing of the frame  20  so that the screen  18  has substantially the same tautness along its length and height, the middle hinge assemblies  32  and corner hinge assemblies  30  are preferably configured to cant the frame members  22 ,  24 ,  26 ,  28  outwardly at the midpoints so that when the screen  18  is attached, the force exerted by the stretch-fabric  18  will pull the frame members inwardly to produce a more true parallelogram-shaped backwall with substantially square corners and substantially parallel opposing sides resulting in a substantially distortion free projected image. It should be appreciated that the amount of canting required for the frame members will vary depending on the size of the frame, the tautness of the screen  18 , and the amount of play in the middle and corner hinge assemblies due to manufacturing tolerances. 
       FIGS. 12-20  illustrate the preferred steps for collapsing or folding the backwall  12 . As illustrated in  FIGS. 12 and 13 , to begin collapsing or folding the backwall  12 , the vertical frame members  28   a ,  28   b  are unlocked by pulling the knob  88  on the middle hinge assembly  32  outwardly. The same operation is performed on the other vertical frame members  26   a ,  26   b . As illustrated in  FIGS. 14-16 , once the vertical frame members  26 ,  28  are collapsed, the feet  34 ,  36  are removed from the backwall frame  20  as previously described. Referring now to  FIGS. 17-19 , the top and bottom frame members  22 ,  24  are folded by pulling on the knobs  88  of the middle hinges  32  and bending the frame members  22   a ,  22   b  and  24   a ,  24   b  toward one another. The fully collapsed backwall  12  is illustrated in  FIG. 20 . 
     The foregoing description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment of the apparatus, and the general principles and features of the system and methods described herein will be readily apparent to those of skill in the art. Thus, the present invention is not to be limited to the embodiments of the apparatus, system and methods described above and illustrated in the drawing figures, but is to be accorded the widest scope consistent with the spirit and scope of the appended claims.