Abstract:
An optical panel system including stackable waveguides is provided. The optical panel system displays a projected light image and comprises a plurality of planar optical waveguides in a stacked state. The optical panel system further comprises a support system that aligns and supports the waveguides in the stacked state. In one embodiment, the support system comprises at least one rod, wherein each waveguide contains at least one hole, and wherein each rod is positioned through a corresponding hole in each waveguide. In another embodiment, the support system comprises at least two opposing edge structures having the waveguides positioned therebetween, wherein each opposing edge structure contains a mating surface, wherein opposite edges of each waveguide contain mating surfaces which are complementary to the mating surfaces of the opposing edge structures, and wherein each mating surface of the opposing edge structures engages a corresponding complementary mating surface of the opposite edges of each waveguide.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   This invention was made with Government support under Contract No. DE-AC02-98CH10886 awarded by the Department of Energy. The Government has certain rights in this invention. 

   FIELD OF THE INVENTION 
   The present invention relates generally to the field of optical panels, and, more specifically, to optical panel systems including stackable waveguides. 
   BACKGROUND OF THE INVENTION 
   For large venues, e.g. stadiums, arenas, theaters, fields, etc., large jumbotron-type display screens have been widely used to display various images to audiences attending events such as, for example, sporting events, theatrical events, movies, concerts, speeches, etc. Although these large display screens do an adequate job of displaying images to vast numbers of people, the large size of the displays makes their assembly at venues extremely difficult and time-consuming. Moreover, the sheer size of these display screens requires complicated and expensive procedures and techniques to transport the display screens from venue to venue. 
   Thus, it is desirable to provide a display screen which is able to overcome the above disadvantages and which can be quickly and easily assembled in situ and subsequently disassembled for transport in an inexpensive and efficient fashion. 
   It is therefore desirable to provide an optical panel system including stackable waveguides that can be utilized in large-size venue situations (as well as any size venue situation), and that does not suffer from the above drawbacks experienced by large display screens. Additionally, while addressing these problems, the optical panel system including stackable waveguides of the present invention will simultaneously provide superior high contrast desired in high ambient light situations (or any light situation). 
   These and other advantages of the present invention will become more fully apparent from the detailed description of the invention hereinbelow. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to an optical panel system for displaying a projected light image, comprising a plurality of planar optical waveguides in a stacked state, each waveguide having a first end and a second end, wherein an inlet face is defined by the plurality of first ends. The optical panel system also comprises a support system that aligns and supports the waveguides in the stacked state such that the waveguides are in a predetermined configuration, wherein each waveguide is held in position relative to an adjacent waveguide using the support system while the waveguides are in the predetermined configuration. The support system may comprise at least one rod, wherein each waveguide contains at least one hole, and wherein each rod is positioned through a corresponding one of the at least one hole to thereby provide the waveguides in the predetermined configuration. 
   The support system may alternatively comprise at least two opposing edge structures having the waveguides positioned therebetween, and wherein the at least two opposing edge structures engage opposite edges of each waveguide to thereby provide the waveguides in the predetermined configuration. At least one of the at least two opposing edge structures may be a rod. 
   At least one of the at least two opposing edge structures may contain a mating surface, wherein at least one of the opposite edges of each waveguide may contain a mating surface which is complementary to the mating surface of the at least one opposing edge structure, and wherein each mating surface of the at least one opposing edge structure may engage a corresponding complementary mating surface of the at least one of the opposite edges of each waveguide to thereby provide the waveguides in the predetermined configuration. At least one mating surface of the at least one opposing edge structure may be substantially dovetail-shaped, substantially L-shaped, or substantially U-shaped. The opposing edge structures may contain a plurality of waveguide positioning elements which position each waveguide a predetermined distance from an adjacent waveguide. 
   The waveguides may comprise transparent strips formed of a material have a first index of refraction, and wherein each of the strips is surrounded by air having a second index of refraction which is lower than the first index of refraction while the waveguides are in the predetermined configuration. A black strip may be positioned between each of the strips surrounded by air. 
   Alternatively, the waveguides may comprise transparent strips formed of a material having a first index of refraction, and wherein each of the strips has a coating on each side thereof of a cladding material having a second index of refraction which is lower than the first index of refraction. At least one of the cladding material coatings of each strip may have a black layer coating thereon. 
   The optical panel system may further comprise at least one coupler provided at the inlet face to thereby redirect image light entering the inlet face. Each of the plurality of first ends of the waveguides may be beveled such that the inlet face is serrated to thereby redirect image light entering the inlet face. 
   An outlet face may be defined by the plurality of second ends, and wherein each of the plurality of second ends of the waveguides may be beveled such that the outlet face is serrated to thereby redirect image light emitted from the outlet face. 
   The optical panel system may further comprise a plurality of waveguide positioning elements (which differ from the waveguide positioning elements of the opposing edge structures described above) which position each waveguide a predetermined distance from an adjacent waveguide. The waveguide positioning elements in this embodiment may be located between adjacent waveguides such that each waveguide is surrounded by air while the waveguides are in the predetermined configuration. These waveguide positioning elements may comprise particulates. 
   In one embodiment, each waveguide may comprise a plurality of planar sub-waveguides, wherein each sub-waveguide may be bonded to an adjacent sub-waveguide within each waveguide. Each sub-waveguide may comprise a transparent strip formed of a material having a first index of refraction, and wherein the strip has a coating on each side thereof of a cladding material having a second index of refraction which is lower than the first index of refraction. A sub-inlet face may be defined by each first end of each waveguide, wherein the optical panel system may further comprise at least one coupler provided at each sub-inlet face of each waveguide to thereby redirect image light entering the sub-inlet face. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the present invention to be clearly understood and readily practiced, the present invention will be described in conjunction with the following figures, wherein: 
       FIG. 1  is an isometric view, in partially broken away form, illustrating an optical panel system including a light directing film, in accordance with a preferred embodiment of the present invention. 
       FIG. 2  is an isometric view of a waveguide strip, in accordance with a preferred embodiment of the present invention. 
       FIG. 3  is a cross-sectional side view of a waveguide strip coated on each side thereof with a cladding layer and with a black layer, in accordance with a preferred embodiment of the present invention. 
       FIG. 4  is an isometric view of a partially constructed optical panel system including support rods which are provided through holes in each waveguide, in accordance with a preferred embodiment of the present invention. 
       FIG. 5  is an exploded plan view of an optical panel system including two opposing edge support structures which contain dovetail mating surfaces, and including a stack of waveguides with opposite edges containing mating surfaces which are complementary to that of the mating surfaces of the opposing edge support structures, in accordance with a preferred embodiment of the present invention. 
       FIG. 6  is a plan view of an optical panel system including four opposing edge support structures which contain L-shaped mating surfaces, and including a stack of waveguides with opposite edges containing mating surfaces which are complementary to that of the mating surfaces of the opposing edge support structures, in accordance with a preferred embodiment of the present invention. 
       FIG. 7  is a plan view of an optical panel system including two opposing edge support structures which contain U-shaped mating surfaces, and including a stack of waveguides with opposite edges containing mating surfaces which are complementary to that of the mating surfaces of the opposing edge support structures, in accordance with a preferred embodiment of the present invention. 
       FIG. 8  is a plan view of an optical panel system including six opposing edge support structures in the form of support rods, and including a stack of waveguides with opposite edges engaging the opposing edge support structures, in accordance with a preferred embodiment of the present invention. 
       FIG. 9  is a side view of a waveguide stack including an angled waveguide configuration between parallel inlet and outlet faces, in accordance with a preferred embodiment of the present invention. 
       FIG. 10  is a side view of a waveguide stack including an inlet face which is non-parallel to an outlet face, in accordance with a preferred embodiment of the present invention. 
       FIG. 11  is a side view of a waveguide stack which is trapezoidal-shaped including an inlet face which is non-parallel to an outlet face, in accordance with a preferred embodiment of the present invention. 
       FIG. 12  is a side view of a waveguide stack including light-directing serrations at an outlet face, in accordance with a preferred embodiment of the present invention. 
       FIG. 13  is a side view of a waveguide stack including light-directing prisms at an inlet face, in accordance with a preferred embodiment of the present invention. 
       FIG. 14  is an isometric view of a waveguide stack including curved inlet and outlet faces, in accordance with a preferred embodiment of the present invention. 
       FIG. 15  is a front view of an optical panel system provided in three modular sections including support rods which are provided through holes in each waveguide of each modular section, in accordance with a preferred embodiment of the present invention. 
       FIG. 16  is a front view of an optical panel system including waveguide positioning elements comprising particulates, in accordance with a preferred embodiment of the present invention. 
       FIG. 17  is a front view of an optical panel system including waveguide positioning elements comprising tabs, in accordance with a preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   It is to be understood that the figures and descriptions of the present invention may have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements found in a typical optical panel system. Those of ordinary skill in the art will recognize that other elements may be desirable and/or required in order to implement the present invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. It is also to be understood that the drawings included herewith only provide diagrammatic representations of the presently preferred structures of the present invention and that structures falling within the scope of the present invention may include structures different than those shown in the drawings. Reference will now be made to the drawings wherein like structures are provided with like reference designations. 
   Illustrated in  FIG. 1  is an optical panel system  10  in accordance with an exemplary embodiment of the present invention. The display is an assembly of components including an optical panel  12  having any desired aspect ratio of horizontal width to vertical height for any desired application. An exemplary large video image optical panel is illustrated, and may have a diagonal screen measurement of 15 feet for example. Although smaller or larger diagonal screen measurements may be contemplated. 
   The optical panel  12  cooperates with a projector  16  suitably configured for projecting image light  18  in the form of a beam through the panel for producing a video image  18   a  for direct viewing by an observer facing the panel. The projector  16  may take any conventional form capable of projecting a viewable image. 
   For example, the image beam  18  is initially generated as plain, unmodulated light in a suitable light source, which may be a bright incandescent bulb, or laser, or any other suitable light source. The initial light may be monochromatic, or have color as desired. 
   The plain light is then spatially modulated in a modulator for creating individual picture elements, or pixels, which define the desired video image or pattern. The modulator may take any conventional form such as a liquid crystal display (LCD) or a Digital Micromirror Device (DMD). 
   The LCD is a light transmissive device having portions which are selectively rendered opaque for selectively interrupting the light at selected pixels. The DMD is a light reflective device and has individual micromirrors which are selectively tiltable to reflect the light toward the panel or away therefrom for defining corresponding pixels. 
   Suitable imaging optics, including lenses, may be optically aligned between the panel and the light modulator for horizontally and vertically scaling and focusing the image beam as required over the back side of the panel for transmission therethrough. The light source, modulator, and imaging optics may be connected as one integral unit, or the location of each of these components may differ as desired. For example, each component may be separate from one another by some distance. 
   The optical panel  12  is comprised of a plurality of stacked optical waveguides  30  comprising cores/strips  30   a  of polymer, plastic, or glass, or combinations thereof. In a preferred embodiment, plexiglas® would be selected as the preferred material for the core  30   a  of the stacked waveguides  30 .  FIG. 2  illustrates exemplary dimensions (i.e. not drawn to scale) of one of the cores/strips  30   a  forming a waveguide  30 , with S 1  (length)=1 inch, S 2  (width)=10 feet, and S 3  (thickness)=¼ inch. Of course, the dimensions and size of the strips  30   a  may differ from this example. Additionally, the size and dimensions of each of the individual strips  30   a  may either be substantially identical or different from other strips  30   a  within the same stack of waveguides  30 . The waveguides are preferably planar (i.e. in the form of flat ribbons) extending continuously in the horizontal direction along the entire optical panel. 
   Each waveguide  30  has a first end  30   e  and a second end  30   f  (see, for example,  FIGS. 4–13 ), wherein an inlet face  20  is defined by the plurality of first ends  30   e , and wherein an outlet face  22  is defined by the plurality of second ends  30   f . Also shown in  FIG. 1  is an optional light coupler  19  which is provided at the inlet face  20  to thereby redirect image light  18  entering the inlet face  20 . 
   In one embodiment, the optical panel  12  is comprised of waveguide  30  comprising optically transparent strips  30   a  (having, for example, a refractive index n=1.49) surrounded by air (having, for example, a refractive index n=1) between the strips. To provide even a microscopic layer of air, the strips may be placed directly on one another. In this case, this microscopic layer of air is sufficient in functioning as a relatively low index of refraction material as compared to the material comprising the strips, thereby resulting in substantially total internal reflection (TIR) of image light  18  from the inlet face  20  to the outlet face  22 . 
   In another embodiment, a black layer (of dark color or black material, both referred to as “black” herewithin) may be added between each of the transparent strips in order to increase contrast of the optical panel  12 . This black layer would help to absorb ambient light. It would also make the screen appear significantly darker thereby improving contrast. A thin black layer of, for example, a polymer could be placed between each of the strips in  FIG. 1 . Each of the transparent strips could be ¼ inch (see S 3  in  FIG. 2 ) while each of the black layers may be as thin as 0.0005 inch for example. A thicker black layer may be more practical for construction and handling purposes. Of course, smaller or larger black layer thicknesses may be contemplated. The black layers may preferably have the same length and width (i.e. FIG.  2 &#39;s S 1  and S 2 , respectively) as that of the strips. 
   Instead of relying on a microscopic layer of air between each strip, the strips may be intentionally separated via utilization of a plurality of waveguide positioning elements such that the strips are surrounded by air  30   d  while in the stacked state. These waveguide positioning elements may be provided between adjacent strips and may be comprised of particulates  51  ( FIG. 16 ) comprising, for example, a polymer, a plastic, a glass, or combinations thereof. 
   In an alternative embodiment, the opposing edge structures ( 50 ,  150 ,  250 ,  350 ,  450  described below and as illustrated in FIGS.  1  and  4 – 8 ) may include a plurality of waveguide positioning elements to position each strip or waveguide a predetermined distance from an adjacent waveguide. In this embodiment, the waveguide positioning elements may comprise items selected from the group consisting of a bead, hook, indent, groove, protrusion, notch, tab, nail, screw, bolt, spike, pin, brad, tack, or combinations thereof. For example, when utilizing tabs  151  (FIG.  17 —such as the type, for example, used in bookshelves), the waveguides would rest on the tabs  151  which act as a ledge for the edges of the waveguides (similar to the shelves of bookshelves resting on their tabs). Slanted opposing edge structure(s)  550  may optionally be utilized to facilitate stacking of the waveguides onto their corresponding tabs  151 . Of course, slanted opposing edge structures (i.e. at least one or more) may be utilized in any embodiment in this disclosure (e.g. even without the waveguide positioning elements). When utilizing slanted opposing edge structures, the particular stacking order of the waveguides becomes an important factor. 
   In a more preferred embodiment, air would not be utilized as the low index cladding. Rather, the individual strips  30   a  would each be coated with a low index cladding material  30   b  and optionally, a black layer  30   c  as shown in  FIG. 3 . The cladding layers  30   b  have a second index of refraction lower than that of the strips  30   a  for providing substantially TIR of the image light as it is transmitted through the strips  30   a . The cladding may be a suitable plastic or epoxy for example. Alternatively, instead of using a separate black layer  30   c , the cladding material  30   b  itself may be black. The black cladding may be formed in any suitable manner such as with black spray paint, or carbon particles within an epoxy adhesive joining together the adjacent core in one or more cladding layers as desired. 
   As mentioned above, the thickness of the strip (S 3 ) may be ¼ inch, while the combined thickness of the low index cladding  30   b  and the black layer  30   c  (S 4  in  FIG. 3 ) may be 0.0005 inch. In this preferred embodiment, the transparent strip may have a refractive index n=1.49 while the cladding layer may have a refractive index n=1.47 (i.e. rather than 1.0 for air as per the embodiment above). By keeping the refractive indices so close to each other in this preferred embodiment, the acceptance angles of the waveguides are limited to only accept the image light from the projector (i.e. if the projector is positioned at an optimum angle) while rejecting substantially all ambient light. This configuration allows the screen to be much blacker thereby resulting in significantly higher contrast of the displayed image  18   a  at the outlet face  22 . 
   In order to align and support the waveguides  30  in a stacked state, a support system is utilized. In the embodiment illustrated in  FIGS. 1 and 4 , the support system includes 2 rods  50  which are positioned through corresponding holes  50   a  provided in each of the waveguides  30  to thereby provide the strips in a predetermined configuration. The holes may be provided towards, for example, opposite edges of each waveguide, and may be formed by various techniques such as, for example, drilling. To form the stack, the waveguides may be individually placed on the rods or a number of strips may be simultaneously placed on the rods. The waveguides are preferably stacked vertically on top of each other to form the optical panel height, and may number between about 300–3000 waveguides for providing 300–3000 lines of resolution, or more or less as desired. 
   Of course, any number of rods/holes may be contemplated with two of each being the optimum number. The rods  50  may take the form of wires or other forms. The rods may comprise any sufficiently rigid material such as, for example, plastic, glass, carbon fiber, wood, metal, or combinations thereof. The rods may preferably be transparent (e.g. comprised of a material having substantially the same refractive index as that of the strips  30   a ) or they may be comprised of an opaque material. The rods may be round in cross section or have any other cross-sectional shape. The rods preferable are in the form of wires each having a diameter of for example 0.05 inch. Of course, the size of the rods may differ dependent on factors such as, for example, the overall size or weight of the display. 
   In another preferred embodiment, the support system includes at least two opposing edge structures  150  having the waveguides  30  positioned therebetween. The opposing edge structures  150  comprise a sufficiently rigid material and preferably have a dovetail-shaped cross section as illustrated in  FIG. 5 . The dovetail-shaped surfaces  150   a  engage opposite edges of each waveguide  30  (i.e. having a complementary mating dovetail-shaped surface  150   b ) to thereby provide the waveguides in a predetermined configuration. The shape of the mating surfaces may be different than the shape depicted in  FIG. 5  as long as a secure engagement is achieved between the edge structures and the edges of the waveguides. The dovetail shape may be formed in the edge structures using various techniques such as, for example, during molding of the edge structures. Likewise, the complementary dovetail shape may be formed in the waveguides using various techniques such as, for example, by sawing the waveguides while in the predetermined (stacked) configuration. 
   Other types of support systems may be contemplated. For example, the support system may instead utilize opposing edge structures  250  having L-shaped cross-sections which engage the edges of the waveguides at the waveguide corners as illustrated in  FIG. 6 . As another example, the support system may alternatively utilize opposing edge structures  350  having U-shaped cross-sections which engage the edges of the waveguides as illustrated in  FIG. 7 . As yet another example, the support system may alternatively utilize opposing edge structures  450  in the form of rods each having, for example, circular-shaped cross-sections. The rods engage the edges, fronts, and backs of the waveguides as illustrated in  FIG. 8 . Of course, a lesser or greater number of edge structures may be utilized than as depicted in  FIGS. 5–8 . 
   While in the predetermined configuration, the waveguide stack may have the inlet face being substantially parallel to the outlet face, with the inlet face and the outlet face being substantially perpendicular to a direction of image light within each of the waveguides as illustrated in  FIG. 1 . In another embodiment, the waveguide stack may have the inlet face being substantially parallel to the outlet face, with the inlet face and the outlet face being angled relative to a direction of image light within each of the waveguides as illustrated in  FIG. 9 . In another embodiment, the waveguide stack may have the inlet face being angled relative to the outlet face as illustrated in  FIGS. 10 and 11 . In another embodiment, each of the plurality of second ends of the waveguides is beveled such that the outlet face is serrated to thereby redirect image light emitted from the outlet face as illustrated in  FIG. 12 . In another embodiment each of the plurality of first ends of the waveguides is beveled such that the inlet face is serrated to thereby redirect image light entering the inlet face as illustrated in  FIG. 13 . In another embodiment, the waveguide stack may have at least one of the inlet face and the outlet face being curved as illustrated in  FIG. 14 . 
   In another preferred embodiment, rather than providing the optical panel  12  comprised of a waveguide stack comprising single, loose, separable waveguides, the optical panel may instead be provided using a plurality of modular-type waveguide stack sections  12   a ,  12   b ,  12   c  as illustrated in  FIG. 15 . For example, each of the particular sections  12   a ,  12   b ,  12   c  contain waveguides  30  (referred to as sub-waveguides) which function substantially identically to that of the waveguides  30  described in the embodiments above. These sub-waveguides within a particular section are laminated together using known techniques such as, for example, those described in U.S. Pat. No. 6,301,417 issued to Biscardi et al and U.S. Pat. No. 6,487,350 issued to Veligdan et al. Once formed, these sections  12   a ,  12   b ,  12   c  may be substituted for any of the individual waveguides  30  or plurality of waveguides  30  described in the above embodiments, and may be used with any of the support systems described above substantially identically as well.  FIG. 15  illustrates an optional layer of air  30   d  provided between the sections  12   a ,  12   b ,  12   c . The optional layer of air  30   d  may be provided, for example, by any of the waveguide positioning elements  51 ,  151  described above. 
   A coupler may optionally be used at the sub-inlet faces of each of the sections  12   a ,  12   b ,  12   c  to thereby redirect image light entering the sub-inlet faces. This coupler may be in the form of an additional sheet or layer formed on each of the waveguide sections or may be embedded within ends of the individual sub-waveguides prior to or after the lamination process forming the sections. A diffuser may similarly be incorporated/formed at/embedded at the sub-outlet faces. The various forms/formation techniques of the coupler and diffuser described in this embodiment may also be utilized in the other embodiments. 
   U.S. Pat. Nos. 6,301,417 and 6,487,350 describe various materials and formation techniques for waveguide cores (strips), claddings, black layers, and couplers which may be utilized in any of the embodiments described above. 
   The above embodiments describe the optical panel system  10  as the type where image light is received at an inlet face  20  and is displayed at an outlet face  22  (i.e. a pass-through type image projection device). However, it is to be understood that the support system described in the embodiments above may alternatively be employed in a front projection type device such as, for example, that described in U.S. Pat. No. 6,535,674 issued to Veligdan. In this front projection type device, the light is received at an inlet face of a waveguide stack and is reflected by at least one reflector provided at a back face of the waveguides, wherein the reflector redirects the image light back toward the inlet face which simultaneously serves as the outlet face. 
   Those of ordinary skill in the art will recognize that various modifications and variations may be made to the embodiments described above without departing from the spirit and scope of the present invention. For example, the edge structure(s) from one embodiment (e.g.  FIG. 5 ) may be utilized in combination with edge structure(s) from other embodiment(s) (e.g.  FIG. 7 ). In one example, the dovetail engagement configuration depicted in  FIG. 5  may be utilized on one edge of the waveguide stack while the other edge of the waveguide stack may utilize the U-Shaped engagement configuration depicted in  FIG. 7 . It is therefore to be understood that the present invention is not limited to the particular embodiments disclosed above, but it is intended to cover such modifications and variations as defined by the following claims.