Abstract:
A collapsible backlight system for providing wide area back lighting for display assemblies, and adapted to remain fully assembled in transition between storage, transportation, setup and use. A flexible sheet includes a plurality of sheaths adapted to substantially protectively envelop individual elongated light sources. The collapsible backlight system has expanded and collapsed configurations. In expanded configuration, the flexible sheet is generally planar and the elongated light sources are spatially dispersed. In collapsed configuration, the elongated light sources are maintained proximal to each other in generally parallel fashion, and the collapsible backlight system can be carried and transported in compact form without causing damage to the elongated light sources. The flexible sheet may have front and rear layers, each such layer possessing selected optical qualities such as translucency, reflectivity and diffusivity, depending on the desired application. Discrete interstices between such layers may define the sheaths which substantially protectively envelope the elongated light sources.

Description:
RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to the field of backlight systems. More particularly, the invention concerns a collapsible backlight system for use in connection with portable display assemblies such as those commonly used for decoration and advertising in retail establishments, trade shows, and the like. 
       BACKGROUND OF THE INVENTION 
       [0003]    Backlight systems are commonly used to illuminate displays in homes, museums, retail stores, airport terminals, trade show exhibits, and the like. In the trade show environment, for example, they are frequently used to illuminate preprinted display panels. In some cases, light boxes are used to simultaneously provide support for the display panel as well as the backlight system. Because backlight systems are frequently used in conjunction with portable display assemblies at trade shows, where time and space can be very limited, a preferable backlight system is one which can be easily and rapidly set up, collapsed and removed in compact form without causing injury to the more fragile components of the system. 
         [0004]    Solutions exist for portable display backlighting systems, particularly those using fluorescent bulbs. Most such systems create an array of fluorescent bulbs by affixing the bulbs or bulb fixtures to a rigid sub frame assembly via a clip, bracket or Velcro mechanism. This generally requires that the sub frame members and the fluorescent fixtures be stored in a disassembled state and then assembled, with significant effort, when needed. 
         [0005]    Light box assemblies that employ the attachment of light sources to non-rigid, or fabric, planar material for support purposes are known. See Hansen U.S. patent application Ser. No. 11/723,955 (Pub. No. US 2008/0010878). However, the attachment means disclosed by Hansen appear to lack characteristics that would effectively protect the attached light sources should the system be collapsed with the light sources remaining attached to the non-rigid planar material. 
         [0006]    Those in the art have long to recognized the need for an improved backlight system that can be stored, transported, set up and used as a complete unit, without the need for assembly or disassembly, and without exposing the light sources to risk of injury in the process. Such a backlight system should also be capable of being set up and collapsed rapidly, and easily transported and stored in compact form. Further, such a system should be useful as part of a light box assembly as well as with alternative backlighting applications that do not involve a light box structure. 
       SUMMARY OF THE INVENTION 
       [0007]    By way of summary, certain embodiments concern a collapsible backlight system capable of remaining in assembled form during and in transition between storage, transport, setup and use. 
         [0008]    A collapsible backlight system for providing wide area back lighting for display assemblies comprises a flexible sheet, a plurality of elongated light sources, and expanded and collapsed configurations. The flexible sheet has a first end, a second end, a first edge and a second edge. The first and second edges generally extend from the first end to the second end. The flexible sheet includes a plurality of sheaths each adapted to substantially protectively envelope an elongated light source. Each of the plurality of elongated light sources is elongated along its respective longitudinal axis and is in substantially protectively enveloped engagement with one of the sheaths. When the collapsible backlight system is in expanded configuration, the flexible sheet is generally planar and the elongated light sources are spatially dispersed. When the collapsible backlight system is in collapsed configuration, the flexible sheet is generally non-planar and the elongated light sources are proximal to each other in generally parallel fashion. Both the expanded and collapsed configurations are adapted to allowing the elongated light sources to remain in the aforementioned substantially protectively enveloped engagement. 
         [0009]    In certain embodiments, the sheaths each have an open end and a detaining end. The open end allows an elongated light source to pass therethrough such that an elongated light source may enter or exit a sheath through the open end of that sheath. In contrast, the detaining end prevents an elongated light source from passing therethrough such that an elongated light source may not enter or exit a sheath through the detaining end of that sheath. The detaining end feature is particularly useful in embodiments in which an elongated light source is oriented in other than substantially horizontal fashion when the collapsible backlight system is suspended in expanded configuration, in which case the detaining end prevents the elongated light source from slipping out of its respective sheath due to, for example, gravity. 
         [0010]    In particular embodiments, each elongated light source comprises a fluorescent lamp. In such cases, each fluorescent lamp generally comprises a fluorescent bulb and a fixture element. The fixture element is generally electrically linkable with additional fixture elements. 
         [0011]    In certain embodiments, each sheath extends in a direction generally from the first edge toward the second edge. In such cases, the sheaths and the respective elongated light sources protectively enveloped thereby are oriented approximately horizontally when the collapsible backlight system is suspended in expanded configuration. In other embodiments, each sheath extends in a direction generally from the first end toward the second end. In such cases, the sheaths and the respective elongated light sources protectively enveloped thereby are oriented approximately vertically when the collapsible backlight system is suspended in expanded configuration. 
         [0012]    In embodiments, the elongated light sources are typically electrically interconnected. Depending on the elongated light sources used, the electrical interconnection may be in parallel or in series. Some such electrical interconnections of elongated light sources are frequently referred to as “daisy-chaining” or “linking” in the art. The electrical interconnection of the elongated light sources is especially useful in portable or tradeshow applications, as it generally requires less wiring to transport and set up. 
         [0013]    In certain embodiments, the plurality of sheaths includes more than two sheaths. In such cases, the sheaths may be sequentially distributed in a direction from approximately the first end of the flexible sheet toward the second end of the flexible sheet, or in a direction from approximately the first edge of the flexible sheet toward the second edge of the flexible sheet. 
         [0014]    In some embodiments, the entirety of the flexible sheet is translucent. This is particularly useful if a single collapsible backlight system is to be used to illuminate two separate displays on opposite sides of the embodiment. In further embodiments, the flexible sheet is translucent proximal the substantially protectively enveloped engagement, or immediately surrounding the elongated light sources, and may not be translucent elsewhere. 
         [0015]    Embodiments typically comprise a suspension structure at generally the first end of the flexible sheet. The suspension structure is adapted to supporting the full weight of the collapsible backlight system while in its expanded configuration. The suspension structure may be suspendedly engaged with the upper frame component of a light box, or where a light box is not used, some other elevated structural component not an integral part of the collapsible backlight system itself. The suspension structure may comprise an elongated dowel or rod secured at generally the first end of the flexible sheet. Alternatively, or in addition, the suspension structure may comprise multiple suspension apertures projecting through the flexible sheet at generally the first end. These suspension apertures may take the form of eyelets, slits, or some other perforations. Generally such suspension apertures are reinforced as necessary to prevent tearing of the flexible sheet at the location of the suspension aperture when the embodiment is being suspended thereby. 
         [0016]    In particular embodiments, the flexible sheet includes a front layer and a rear layer. In such embodiments, each of the sheaths may be substantially defined by discrete interstices between the front and rear layers. In such embodiments, the front layer may be substantially translucent and the rear layer substantially opaque. In other embodiments, the front layer is substantially translucent and said rear layer is substantially light reflective on the face of the rear layer adjacent the above-mentioned discrete interstices. In embodiments, the front and rear layers may be substantially comprised of multiple plies of fabric. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Further advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description of the preferred embodiments and upon reference to the accompanying drawings in which: 
           [0018]      FIG. 1  is a diagrammatic front view of an embodiment of a collapsible backlight system, in expanded configuration; 
           [0019]      FIG. 2  is a diagrammatic side view of the embodiment of  FIG. 1  wherein the front and rear layers of the sheet both extend from generally the first end to the second end, the plurality of sheaths being defined by discrete interstices disposed between the rear layer and the front layer; 
           [0020]      FIG. 3  is a diagrammatic side view of an embodiment similar to that of  FIG. 1  but wherein the front layer of the sheet is divided into individual strips, the plurality of sheaths each being defined by a discrete interstice disposed between the rear layer and a strip of the front layer; 
           [0021]      FIG. 4  is a diagrammatic front view of an embodiment of a collapsible backlight system of  FIG. 1 , shown in collapsed configuration; 
           [0022]      FIG. 5  is a diagrammatic enlarged view of detail  5  of  FIG. 2 ; 
           [0023]      FIG. 6  is a diagrammatic enlarged view of detail  6  of  FIG. 3 ; 
           [0024]      FIG. 7  is a diagrammatic front perspective view depicting an embodiment of a collapsible backlight system employed as part of a light box assembly; 
           [0025]      FIG. 8  is a diagrammatic cross-sectional view taken along line  8 - 8  of  FIG. 7 ; 
           [0026]      FIG. 9  is a diagrammatic front view of a further embodiment of a collapsible backlight system, in expanded configuration; 
           [0027]      FIG. 10  is a diagrammatic front view of the embodiment of  FIG. 9  in which the embodiment has been folded generally in half forming a first transitional configuration toward collapsed configuration; 
           [0028]      FIG. 11  is a diagrammatic front view of the embodiment of  FIG. 9  in which the embodiment has been rolled up forming a second transitional configuration toward collapsed configuration. 
           [0029]      FIG. 12  is a diagrammatic front view of an embodiment of a collapsible backlight system of  FIG. 9 , shown in collapsed configuration and ready for carry; 
           [0030]      FIG. 13  is a diagrammatic front view of an additional embodiment of a collapsible backlight system, in expanded configuration and illustrating elongated light sources spatially dispersed in non-parallel fashion; 
           [0031]      FIG. 14  is a diagrammatic front view of the embodiment of  FIG. 13  in which the embodiment has been compressed to arrange the elongated light sources proximally in parallel fashion forming a first transitional configuration toward collapsed configuration; 
           [0032]      FIG. 15  is a diagrammatic front view of the embodiment of  FIG. 13  in which the embodiment has been folded generally in half forming a second transitional configuration toward collapsed configuration; 
           [0033]      FIG. 16  is a diagrammatic front view of an embodiment of a collapsible backlight system of  FIG. 13 , shown in collapsed configuration and ready for carry. 
       
    
    
       [0034]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Referring to the drawings, several embodiments of a collapsible backlight system according to the present invention are shown generally at  20 . Turning to  FIG. 1  for illustration, a collapsible backlight system  20  is shown in expanded configuration. A flexible sheet  22  has a first end  24 , a second end  26 , a first edge  28  and a second edge  30 . First edge  28  and second edge  30  generally extend from first end  24  to second end  26 . As shown in  FIGS. 1 and 9 , for example, when collapsible backlight system  20  is in expanded configuration, first edge  28  and second edge  30  may be substantially linear. In alternate embodiments such as the one depicted in  FIG. 13 , first edge  28  and second edge  30  may be substantially non-linear, for example, tracing a more curved, wavy or jagged pathway which may conform to the particular requirements of the display form to be illuminated or the structure supporting or housing collapsible backlight system  20 . In similar fashion, first end  24  and second end  26  may also be substantially non-linear in particular embodiments when in expanded configuration. 
         [0036]    Flexible sheet  22  includes a plurality of sheaths (a typical such sheath is shown at  32 ). Each sheath  32  is adapted to substantially protectively envelop an elongated light source (a typical such elongated light source is shown at  34 ). As illustrated in  FIG. 1 , in certain embodiments each sheath  32  extends in a direction generally from first edge  28  to second edge  30 . When such embodiments are in expanded configuration (as shown, for example, in  FIG. 1 ), the plurality of sheaths  32  are typically sequentially distributed in a direction from approximately first end  24  toward second end  26 . In other embodiments, as illustrated for example in  FIG. 9 , each sheath  32  may extend in a direction generally from first end  24  toward second end  26 . When such embodiments are in expanded configuration (as shown, for example, in  FIG. 9 ), the plurality of sheaths  32  are typically sequentially distributed in a direction from approximately first edge  28  toward second edge  30 . In yet further embodiments, as illustrated for example in  FIG. 13 , sheaths  32 , and their respective substantially protectively enveloped elongated light sources  34 , may be arranged in various non-parallel fashions when collapsible backlight system  20  is in expanded configuration. 
         [0037]    Each of a plurality of elongated light sources  34  are in substantially protectively enveloped engagement with a sheath  32 . In individual embodiments, the plurality of elongated light sources  34  may be electrically interconnected in series, in parallel, or a combination thereof. Such interconnections may be made by one or more connector cables (examples of which are shown at  36 ). In certain embodiments, elongated light source  34  may comprise a fluorescent lamp. Such a fluorescent lamp would typically comprise a fixture element and a fluorescent bulb element. The substantially protectively enveloped engagement helps ensure that, with no need to disassemble collapsible backlight system  20 , the elongated light sources  34  remain undamaged throughout storage, transportation, setup and use of collapsible backlight system  20 . 
         [0038]    Embodiments may comprise a suspension structure located generally at first end  24 . The suspension structure may be adapted to support the full weight of collapsible backlight system  20  while in expanded configuration, or a significant portion of that weight. Turning to  FIGS. 1 ,  9  and  13 , the suspension structure may be defined by an elongated dowel  38 , multiple suspension apertures  40 , or a combination thereof. 
         [0039]      FIGS. 7 and 8  depict a light box  48  within which a collapsible backlight system  20  is suspended by way of hanger elements  50 . In such an application, light box  48  acts as the support structure for collapsible backlight system  20 , the support structure being supportingly associated with the suspension structure of the embodiment by way of, for example, hanger element  50 . Hangar elements  50  can be straps, hooks, cables, ropes, or other conventionally known support components. Further, it should be noted that collapsible backlight system  20  can be used to provide backlighting for displays and images that are not directly associated with a light box, in which case the embodiment can be suspended from, for example, a ceiling or other load-bearing framework. In embodiments in which elongated light sources  34  each comprise a fluorescent bulb and linkable fixture, no separate fluorescent light ballasts are required. Rather, the entire system can be powered by directly plugging power plug  54  into a wall outlet or a standard energized power strip. In  FIG. 7 , access door  60  of light box  48  is shown in open position. Power plug  54  is shown passed through plug aperture  52 . 
         [0040]    As illustrated in  FIGS. 5 and 6 , in embodiments of collapsible backlight system  20 , flexible sheet  22  may include a front layer  44  and a rear layer  46 . In some such embodiments, each sheath  32  is substantially defined by a discrete interstice between front layer  44  and rear layer  46 . In embodiments with a front and rear layer, both front layer  44  and rear layer  46  may extend substantially from first end  24  to second end  26  (see, for example,  FIGS. 2 and 5 ). Alternatively, one layer may be divided into individual strips secured to the other layer by way of stitching, adhesive, or similar conventional securing operation (see, for example,  FIGS. 3 and 6 , which depict front layer  44  divided into individual strips). 
         [0041]    In some embodiments, substantially all of flexible sheet  22  may posses a selected degree of translucency or diffusivity. Alternatively, in other embodiments, flexible sheet  22  may be translucent only proximal the substantially protectively enveloped engagement, or immediately surrounding elongated light sources  34 , and opaque or diffusive elsewhere. In embodiments in which flexible sheet  22  is at least partially diffusive, the diffusivity causes a spreading of the transmitted light from elongated light sources  34  throughout flexible sheet  22 , which in turn provides a more even backlighting of the display panel or other object to be illuminated (see, for example, front display panel  56  and rear display panel  58  in  FIG. 8 ). 
         [0042]    Depending on the intended use of an embodiment with a front and rear layer, the translucency, diffusivity and reflectivity of front layer  44  and rear layer  46  may differ. Returning to  FIGS. 7 and 8 , in embodiments intended to be used to back illuminate only one display panel (for example, front display panel  56 ), front layer  44  may be substantially translucent and rear layer  46  may be substantially opaque. In embodiments intended to be used to back illuminate display panels on both sides of a two-sided light box display (for example, front display panel  56  and rear display panel  58 ), both front layer  44  and rear layer  46  may be substantially translucent. To help optimize the efficient illumination of the side of a light box display adjacent front layer  44 , front layer  44  may be substantially translucent and rear layer  46  may be substantially light reflective on the face of rear layer  46  adjacent the discrete interstices. In certain embodiments with front and rear layers, each of front layer  44  and rear layer  46  may be substantially comprised of multiple plies of fabric, each ply selected to contribute particular desired optical and structural characteristics to collapsible backlight system  20 . 
         [0043]    Each embodiment of collapsible backlight system  20  comprises an expanded configuration and a collapsed configuration. Importantly, collapsible backlight system  20  is able to remain fully assembled while in, and throughout the transition between, these configurations.  FIGS. 1 ,  9  and  13  each depict a distinctive embodiment of collapsible backlight system  20  in expanded configuration. When collapsible backlight assembly  20  is in expanded configuration, flexible sheet  22  is generally planar and elongated light sources  34  are spatially dispersed.  FIGS. 4 ,  12  and  16  depict the same embodiments depicted in  FIGS. 1 ,  9 , and  13 , but in their respective collapsed configurations. When collapsible backlight system  20  is in collapsed configuration, flexible sheet  22  is generally non-planar, and elongated light sources  34  are proximal to each other in generally parallel fashion. 
         [0044]    Certain embodiments of collapsible backlight system  20  may comprise transitional configurations between the expanded and collapsed configurations. For example,  FIGS. 9-12  and  13 - 16  respectively depict the transition of two separate embodiments of a collapsible backlight system  20  between expanded configuration (see  FIGS. 9 and 13 , respectively) and collapsed configuration (see  FIGS. 12 and 16 , respectively). First transitional configurations are shown at  FIGS. 10 and 14 , respectively. Second transitional configurations are shown at  FIGS. 11 and 15 , respectively. 
         [0045]      FIGS. 9-12  collectively depict one embodiment of a collapsible backlight system  20  in transition between expanded configuration and collapsed configuration.  FIG. 9  shows the embodiment in expanded configuration.  FIG. 10  shows the embodiment of  FIG. 9  in a first transitional configuration, wherein flexible sheet  22  is folded approximately in half across fold line  64 .  FIG. 11  illustrates a second transitional configuration wherein the embodiment precedingly in its first transitional configuration has now been rolled up in a direction generally from second edge  30  toward first edge  28 . Finally,  FIG. 12  depicts the same embodiment of  FIG. 9 , but in collapsed configuration, capable of being carried by way of, for example, carrying strap  62 . Strap  42 , or a conventional equivalent such as an elastic band, belt, string, rope, latch, tape, hook or Velcro joint may be used to further secure the embodiment in collapsed configuration for transportation and storage purposes. 
         [0046]      FIGS. 13-16  collectively depict another embodiment of a collapsible backlight system  20  in transition between expanded configuration and collapsed configuration.  FIG. 13  shows the embodiment in expanded configuration.  FIG. 14  shows the embodiment of  FIG. 13  in a first transitional configuration, wherein the elongated light sources  34  have been gathered proximal to each other in generally parallel fashion.  FIG. 15  illustrates a second transitional configuration wherein the embodiment precedingly in its first transitional configuration has now been folded approximately in half across fold line  64 . Finally,  FIG. 16  depicts the same embodiment of  FIG. 13 , but in collapsed configuration, wherein a draw string  66  has been placed through suspension apertures  40  and tightened to secure the embodiment in collapsed configuration while simultaneously providing a carrying loop. Again, strap  42 , or a conventional equivalent thereof, may be used to further secure the embodiment in collapsed configuration for transportation and storage purposes. 
         [0047]    Turning now to  FIGS. 9 and 13 , in certain embodiments, sheaths  32  include an open end  68  and a detaining end  70 . Open end  68  allows an elongated light source  34  to pass therethrough so as to enter and exit sheath  32 . Detaining end  70  prevents an elongated light source  34  from passing therethrough so as to preclude an elongated light source  34  from exiting a sheath  32  as a result of, for example, the force of gravity. In certain embodiments, detaining ends  70  include access holes large enough to allow the insertion and removal of a connector cable  36 . 
         [0048]    The detailed description of embodiments of the collapsible backlight system is intended to serve merely as examples, and is in no way intended to limit the scope of the appended claims to these described embodiments. Accordingly, modifications to the embodiments described are possible, and it should be clearly understood that the invention may be practiced in many different ways than the embodiments specifically described below, and still remain within the scope of the claims.