Patent Publication Number: US-10761250-B2

Title: Photo-luminescent visual elements, systems and methods

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This non-provisional utility application is a continuation of non-provisional utility application Ser. No. 15/586,425, filed May 4, 2017, entitled “Photo-luminescent Visual Elements, Systems and Methods”. Application Ser. No. 15/586,425 claimed the benefit of non-provisional utility application Ser. No. 15/004,310, filed Jan. 22, 2016, entitled “Photo-luminescent Display System and Methods”. Application Ser. No. 15/004,310 claimed the benefit of U.S. provisional Application No. 62/107,573, filed Jan. 26, 2015, entitled “Photo-luminescent Display System”. Application Nos. 62/107,573, 15/004,310, and 15/586,425 are incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     DESCRIPTION OF ATTACHED APPENDIX 
     Not Applicable. 
     BACKGROUND 
     This invention relates generally to display devices and systems. Display devices and systems are found in a huge variety of contexts encountered in daily life. When used for advertising and marketing, display systems may be used to make the public aware of various brands, products, services, and other items that are of particular interest to their respective advertisers and marketers. Appealing, interesting, and eye-catching displays of visual advertising or marketing messages can be very effective at generating interest, engagement, and loyalty in the viewing public. 
     Photo-luminescent materials absorb electromagnetic (EM) energy from the sun or from man made light sources. The absorbed EM energy is then radiated at a different wavelength. Some photo-luminescent materials radiate absorbed EM energy quickly while others radiate the absorbed EM energy slowly over the span of minutes to hours. Some photo-luminescent materials absorb EM energy at wavelengths outside the normal human visual spectrum and they radiate EM energy at wavelengths within the normal human visual spectrum. Photo-luminescent materials can be used to create appealing, interesting, and eye-catching visual elements. In consideration of the foregoing points, it is clear that embodiments of the present disclosure confer numerous advantages and are therefore highly desirable. 
     SUMMARY 
     The present disclosure is directed to systems and methods that create eye-catching displays of visual advertising or marketing messages. Embodiments of the present disclosure incorporate one or more photo-luminescent visual elements which are activated by one or more remotely located EM emitters to effectively stimulate photo-luminescent emissions of said photo-luminescent visual elements. 
     Exemplary Embodiment 1.0 {a Minimal System} 
     A display system according to an embodiment of the present disclosure comprises: a photo-luminescent visual element receiving, from an emitter, an incoming electromagnetic radiation at a first wavelength and radiating an outgoing electromagnetic radiation at a second wavelength; said emitter producing said incoming electromagnetic radiation such that at least a portion of said photo-luminescent visual element is illuminated; said first wavelength located outside of the visible spectrum; said second wavelength located in the visible spectrum; and said emitter further characterized in that it is located remotely from said photo-luminescent visual element. 
     Exemplary Embodiment 1.1 {1.0 Plus More than One Emitter} 
     In a related embodiment, a display system according to an embodiment of the present disclosure comprises: a photo-luminescent visual element receiving, from one or more emitters, incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said one or more emitters producing said incoming electromagnetic radiation such that at least a portion of said photo-luminescent visual element is illuminated; said first wavelength located outside of the visible spectrum; said second wavelength located in the visible spectrum; and said emitter further characterized in that it is located remotely from said photo-luminescent visual element. 
     Exemplary Embodiment 1.2 {1.1 Plus More than One Visual Element} 
     In a related embodiment, a display system according to an embodiment of the present disclosure comprises: a plurality of photo-luminescent visual elements receiving, from one or more emitters, incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said one or more emitters producing said incoming electromagnetic radiation such that at least a portion of said plurality of photo-luminescent visual elements are illuminated; said first wavelength located outside of the visible spectrum; said second wavelength located in the visible spectrum; and said emitter further characterized in that it is located remotely from said photo-luminescent visual element. 
     Exemplary Embodiment 2.0 {Basic System 1.0 Plus a Substrate on which the Pigment is Coupled, Viewing Plane is Substantially Transparent to Second Wavelength} 
     A display system according to an embodiment of the present disclosure comprises: a substrate having a pigment side and a viewing side; coupled to said pigment side of said substrate a photo-luminescent pigment receiving from an emitter an incoming electromagnetic radiation at a first wavelength and radiating an outgoing electromagnetic radiation at a second wavelength; said emitter producing said incoming electromagnetic radiation such that at least a portion of said photo-luminescent pigment is illuminated; said first wavelength located outside of the visible spectrum; said second wavelength located in the visible spectrum; said emitter further characterized in that it is located remotely from said photo-luminescent visual element; and, said substrate at least partially transparent to said second wavelength. 
     Exemplary Embodiment 2.0a 
     The embodiment of 2.0 further characterized in that the viewing side and the pigment side are the same side. 
     Exemplary Embodiment 2.1 {Basic System 2.0 Plus the Outgoing EM Radiation is Uniformly Viewable from Both Sides} 
     The system according to embodiment 2.0 additionally characterized in that: the outgoing electromagnetic radiation at said second wavelength comprises an obverse portion passing through said substrate and a reverse portion that does not pass through said substrate, and further characterized in that the energy contents of said obverse portion and said reverse portion differ by no more than the least noticeable difference. In some applications the least noticeable difference is about 20% or less, in other applications it is about 10% or less, and in still other applications it is about 5% or less. 
     Exemplary Embodiment 2.2 {2.0 Plus Substrate is Substantially Opaque to First Wavelength} 
     The system of according to embodiment 2.0 additionally characterized in that: said substrate is substantially opaque to said first wavelength. 
     Exemplary Embodiment 2.3 {2.0 Plus a Second Substrate Between the Emitter and the Pigment} 
     A display system according to an embodiment of the present disclosure comprises: a first substrate having a pigment side and a viewing side; coupled to said pigment side of said first substrate a photo-luminescent pigment receiving, from an emitter, an incoming electromagnetic radiation at a first wavelength and radiating an outgoing electromagnetic radiation at a second wavelength; a second substrate disposed between said emitter and said photo-luminescent pigment such that at least a portion of said incoming electromagnetic radiation passes through said second substrate; said emitter producing said incoming electromagnetic radiation such that at least a portion of said photo-luminescent pigment is illuminated; said first wavelength located outside of the visible spectrum; said second wavelength located in the visible spectrum; said emitter further characterized in that it is located remotely from said photo-luminescent pigment; said first substrate and said second substrate substantially transparent to said second wavelength; and, said second substrate at least partially transparent to said first wavelength. 
     Exemplary Embodiment 2.4 {System 2.3 Plus the Outgoing EM Radiation is Uniformly Viewable from Both Sides} 
     The system according to embodiment 2.0 additionally characterized in that: the outgoing electromagnetic radiation at said second wavelength comprises an obverse portion passing through said first substrate and a reverse portion passing through said second substrate, and further characterized in that the energy contents of said obverse portion and said reverse portion differ by no more than about the least noticeable difference. In some applications the least noticeable difference is about 20% or less, in other applications it is about 10% or less, and in still other applications it is about 5% or less. 
     Exemplary Embodiment 3.0 {Adding Reflection Control Features to Planar Substrate} 
     A display system according to an embodiment of the present disclosure comprises: a photo-luminescent visual element receiving an incoming electromagnetic radiation at a first wavelength and radiating an outgoing electromagnetic radiation at a second wavelength; a planar substrate at least partially transparent at said first wavelength and disposed between an emitter and said photo-luminescent visual element, said emitter producing polarized electromagnetic radiation at said first wavelength and in a direction oriented to impinge upon said planar substrate at an angle about the angle defined by the Brewster&#39;s angle between air and said planar substrate; said first wavelength located outside of the visible spectrum; and, said second wavelength located in the visible spectrum. 
     Exemplary Embodiment 4.0 {in which the Photo-Luminescent Material is Nearly Invisible Under Ordinary Light} 
     A photo-luminescent visual element according to an embodiment of the present disclosure comprises: a photo-luminescent region coupled to a substrate, said photo-luminescent region operative to receive an incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said photo-luminescent region additionally characterized in that it is substantially transparent to wavelengths in the range of 400 nanometers to 700 nanometers; and, wherein said substrate is at least partially transparent to said second wavelength. 
     Exemplary Embodiment 5.0 {Self Supporting Structure of Photo-Luminescent Pigment and Transparent Binder} 
     A photo-luminescent visual element according to an embodiment of the present disclosure comprises: a photo-luminescent pigment dispersed in a substantially rigid binder, said photo-luminescent pigment operative to receive an incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said binder further characterized in that it is at least partially transparent to said first wavelength and at least partially transparent to said second wavelength; said binder shaped into an object having a first planar surface through which said incoming electromagnetic radiation passes and a second planar surface through which a portion of said outgoing electromagnetic radiation passes. 
     Exemplary Embodiment 5.1 {Self Supporting Structure of Photo-Luminescent Pigment and Transparent Binder Plus Low Reflection Emitter Arrangment} 
     A photo-luminescent visual element according to an embodiment of the present disclosure comprises: a photo-luminescent pigment dispersed in a rigid binder, said photo-luminescent pigment operative to receive, from an emitter, an incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said binder further characterized in that it is at least partially transparent to said first wavelength and at least partially transparent to said second wavelength; said binder shaped into an object having a first planar surface through which said incoming electromagnetic radiation passes and a second planar surface through which a portion of said outgoing electromagnetic radiation passes; said emitter producing polarized electromagnetic radiation at said first wavelength and in a direction oriented to impinge upon said first planar surface at an angle about the angle defined by the Brewster&#39;s angle between air and said binder. 
     Exemplary Embodiment 6.0 {Self Supporting Structure of Photo-Luminescent Pigment Fused to a Glass Viewing Plane} 
     A photo-luminescent visual element according to an embodiment of the present disclosure comprises: a planar substrate having both a viewing side and a pigment side; a photo-luminescent pigment fused on to said pigment side, said photo-luminescent pigment operative to receive an incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said planar substrate further characterized in that it is at least partially transparent to said second wavelength; said planar substrate shaped such that at least a portion of said outgoing electromagnetic radiation passes through said viewing side; the photo-luminescent visual element further characterized in that: said outgoing electromagnetic radiation at said second wavelength comprises an obverse portion passing through said planar substrate and a reverse portion not passing through said planar substrate, and further characterized in that the energy contents of said obverse portion and said reverse portion differ from each other by no more than about the least noticeable difference. In some applications the least noticeable difference is about 20% or less, in other applications it is about 10% or less, and in still other applications it is about 5% or less. 
     Exemplary Embodiment 6.1 {Self Supporting Structure of Photo-Luminescent Pigment Fused to a Glass Viewing Plane, Pigment is Essentially Transparent at Visible Wavelengths} 
     A photo-luminescent visual element according to an embodiment of the present disclosure comprises: a planar substrate having both a viewing side and a pigment side; a photo-luminescent pigment fused onto said pigment side, said photo-luminescent pigment operative to receive an incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said planar substrate further characterized in that it is at least partially transparent to said second wavelength; said planar substrate shaped such that at least a portion of said outgoing electromagnetic radiation passes through said viewing side; and said photo-luminescent pigment additionally characterized in that it is substantially transparent to wavelengths in the range of 400 nm to 700 nm. 
     Exemplary Embodiment 6.1a 
     The embodiment of 6.1 further characterized in that the viewing side and the pigment side are the same side. 
     Exemplary Embodiment 6.2 {Self Supporting Structure of Photo-Luminescent Pigment Fused Between Two Glass Planes} 
     A photo-luminescent visual element according to an embodiment of the present disclosure comprises: a first planar substrate having both a viewing side and a pigment side; a photo-luminescent pigment fused onto said pigment side of said first planar substrate; a second planar substrate having both a viewing side and a pigment side; said pigment side of said second planar substrate fused to said pigment side of said first planar substrate, said photo-luminescent pigment operative to receive an incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said first planar substrate further characterized in that it is at least partially transparent to said second wavelength; said first planar substrate shaped such that at least a portion of said outgoing electromagnetic radiation passes through said viewing side; said second planar substrate further characterized in that it is at least partially transparent to said first wavelength; said second planar substrate shaped such that at least a portion of said incoming electromagnetic radiation passes through said viewing side. 
     Exemplary Embodiment 6.3 {Self Supporting Structure of Photo-Luminescent Pigment Fused Between Two Glass Planes, Pigment being Transparent to Visible Light} 
     A photo-luminescent visual element according to an embodiment of the present disclosure comprises: a first planar substrate having both a viewing side and a pigment side; a photo-luminescent pigment fused onto said pigment side of said first planar substrate; a second planar substrate having both a viewing side and a pigment side; said pigment side of said second planar substrate fused to said pigment side of said first planar substrate, said photo-luminescent pigment operative to receive an incoming electromagnetic radiation at a first wavelength and radiate an outgoing electromagnetic radiation at a second wavelength; said first planar substrate further characterized in that it is at least partially transparent to said second wavelength; said first planar substrate shaped such that at least a portion of said outgoing electromagnetic radiation passes through said viewing side; said second planar substrate further characterized in that it is at least partially transparent to said first wavelength; said second planar substrate shaped such that at least a portion of said incoming electromagnetic radiation passes through said viewing side; and said photo-luminescent pigment additionally characterized in that it is substantially transparent to wavelengths in the range of 400 nm to 700 nm. 
     Exemplary Embodiment 7.0 {Edge Lit Substrate in Contact with a Pattern of Photo-Luminescent Pigment Regions which Collectively Create One or More Photo-Luminescent Visual Elements when Viewed from a Viewing Distance} 
     A display system according to an embodiment of the present disclosure comprises: an emitter producing an incoming electromagnetic (EM) radiation at a first wavelength outside of the visual spectrum, the emitter being optically coupled to a photo-luminescent visual element; said photo-luminescent visual element comprising: a planar substrate having at least one edge adapted to accept said incoming EM radiation; and a plurality of photo-luminescent regions in contact with said planar substrate in which each photo-luminescent region receives a portion of said incoming EM radiation and in which each photo-luminescent region produces by means of photo-luminescence an outgoing EM radiation having a wavelength within the visible spectrum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
         FIG. 1A  shows a perspective view of a photo-luminescent display system according to the present disclosure. Cross section  1 B is indicated on this figure. 
         FIG. 1B  shows a cross sectional view the photo-luminescent visual element and an emitter corresponding to  FIG. 1A . 
         FIG. 2A  shows a perspective view of a photo-luminescent display system according to another embodiment of the present disclosure. Sectional view  2 B is indicated in this figure. 
         FIG. 2B  shows a cross sectional view the photo-luminescent visual element and an emitter corresponding to  FIG. 2A . 
         FIG. 3  shows a cross sectional schematic view according to another embodiment of the present disclosure having one or more emitters. 
         FIG. 4  shows a cross sectional schematic view according to another embodiment of the present disclosure in which a photo-luminescent visual element has one or more photo-luminescent regions. 
         FIG. 5  shows a cross sectional schematic view according to another embodiment of the present disclosure in which a photo-luminescent visual element has a photo-luminescent pigment between a first and a second substrate. 
         FIG. 6  shows a cross sectional schematic view according to another embodiment of the present disclosure in which an emitter emits a polarized incoming EM radiation having an angle of incidence with respect to a planar substrate. 
         FIG. 7  shows a cross sectional schematic view according to another embodiment of the present disclosure in which a photo-luminescent visual element comprises a photo-luminescent pigment in dispersed in a rigid binder. 
         FIG. 8  shows a schematic cross sectional view according to another embodiment of the present disclosure in which a photo-luminescent visual element comprises a photo-luminescent pigment fused to a substrate. 
         FIG. 9A  shows a perspective view of a photo-luminescent display system according to the present disclosure. Cross section  9 B and enlargement  9 C are both indicated on this figure. 
         FIG. 9B  shows a cross sectional view the photo-luminescent visual element and an emitter corresponding to  FIG. 9A . 
         FIG. 9C  shows a enlarged view of a plurality of photo-luminescent regions in contact with a planar substrate corresponding to  FIG. 9A . 
     
    
    
     LIST OF REFERENCE NUMBERS APPEARING IN THE FIGURES 
     
         
         
           
               2 —photo-luminescent display system 
               10 —photo-luminescent visual element 
               10   a ,  10   b —first, second photo-luminescent visual element 
               11 —photo-luminescent pigment 
               12 —photo-luminescent region 
               12   a ,  12   b , etc.—first, second, etc. photo-luminescent region 
               13 —photo-luminescent pigment dispersed in a binder 
               20 —substrate 
               20   a ,  20   b —first, second substrates 
               22 —binder 
               24 —planar substrate 
               24   a ,  24   b —first, second planar substrates 
               25 —planar surface 
               25   a ,  25   b —first, second planar surface 
               26 —pigment side 
               27 —substrate edge 
               28 —viewing side 
               30 —emitter 
               30   a ,  30   b —first, second emitter 
               31 —angle of incidence 
               32 —incoming EM radiation at a first wavelength 
               32   a ,  32   b —first, second incoming EM radiation 
               34 —polarized incoming EM radiation at a first wavelength 
               34   a ,  34   b —first, second polarized incoming EM radiation 
               40 —outgoing EM radiation at a second wavelength 
               40   a ,  40   b —first, second outgoing EM radiation 
               42 —obverse portion of outgoing radiation 
               44 —reverse portion of outgoing radiation 
           
         
       
    
     DESCRIPTION 
     Embodiments of the present disclosure provide photo-luminescent display systems and photo-luminescent visual elements suitable for use in such systems. In particular, the present disclosure describes photo-luminescent display systems and elements that improve the ability to create compelling, interesting, and eye-catching displays. 
     Photo-luminescent materials have the following useful property: they absorb electromagnetic (EM) energy at one wavelength and then radiate EM energy at a second wavelength. Depending upon the specific material used, a photo-luminescent material may absorb incoming EM radiation at one or more wavelengths and may radiate outgoing EM radiation at one or more wavelengths. A mixture of photo-luminescent materials may absorb a range of wavelengths while radiating a range of wavelengths. Thus photo-luminescent materials may be selected to suit a variety of particular applications. 
     Preferred photo-luminescent materials in the present disclosure absorb wavelengths in the ultraviolet (UV), below about 400 nanometers, while radiating in the range visible to humans, from around 400 nanometers up to around 700 nanometers. Examples of inorganic photo-luminescent materials include alkaline earth aluminates doped with rare earths, such as strontium aluminate, and zinc sulfide doped with copper. Many other photo-luminescent materials are known in the art and are able to be used in the apparatus and systems of the present disclosure. 
     Embodiments of the present disclosure create one or more photo-luminescent visual elements and illuminate those elements by means of one or more remote emitters. Each photo-luminescent visual element contains one or more photo-luminescent pigments. The remote emitter or emitters provide an incoming electromagnetic radiation to the photo-luminescent pigments at a first wavelength that is effective for being absorbed by the photo-luminescent pigment. After absorbing the incoming EM radiation, the pigment may then radiate a second wavelength of light as outgoing EM radiation. In preferred embodiments, the first wavelength is outside of the visual range of humans and the second wavelength is within the visual range of humans. Shaping the photo-luminescent pigment into one or more symbols, logos, letters, pictures, etc., and illuminating the pigment via one or more emitters creates an eye-catching impression in which a display emits a glow in the form of the shaped pigment and in which the source of illumination is not obvious because the emitter is operating in a wavelength or range of wavelengths that is mostly, substantially, or entirely outside of the human visual range. 
     In some embodiments of the present disclosure, photo-luminescent pigment may be shaped into a thin layer that is effective for allowing the outgoing EM radiation to be visible from all directions. The density and deposition of the pigment layer may be controlled so that outgoing EM radiation energy is substantially uniformly distributed thereby producing a visual impression upon the viewer that the visual article is glowing with about the same intensity when viewed from more than one angle. 
     Incoming EM radiation may be absorbed by a photo-luminescent pigment from a substantially unidirectional source while outgoing EM radiation is emitted omni-directionally. A thin layer or a volume of sufficiently dispersed photo-luminescent pigment will allow the incoming EM radiation to reach a substantial portion of the photo-luminescent pigment for absorption. This improves the uniformity of the outgoing EM radiation emitted by the photo-luminescent pigment. In addition, a thin layer or a volume of sufficiently dispersed photo-luminescent pigment will allow a substantial portion of the emitted radiation to exit the photo-luminescent visual element without being absorbed. Thus the perception in the eye of the viewer of substantially uniform brightness of photo-luminescent emission is improved by thinly layered or thin volumetrically dispersed photo-luminescent pigments. 
     In some embodiments of the present disclosure, photo-luminescent pigment may be selected and applied to or otherwise incorporated into a visual element so that the pigment is substantially transparent to visible light. Such a visual element would be nearly invisible when the emitter is not emitting a wavelength effective for absorption by the photo-luminescent pigment. Upon receiving a wavelength effective for absorption by the photo-luminescent pigment the one or more symbols, logos, letters, pictures, etc. would appear to the viewer and produce a pleasing surprise and thereby very effectively convey an advertising or marketing message. 
     Embodiments of the present disclosure benefit from locating the emitter remotely from the visual element, enhancing the surprise quality of the visual effect by avoiding drawing attention to the emitter. The photo-luminescent visual element can stand by itself at its own location and thereby draw the viewer&#39;s attention more effectively. Locating the emitter remotely from the visual element has other benefits. The uniformity of power density present in the incoming EM radiation may be improved by moving the emitter farther away from the photo-luminescent visual element. The uniformity of the outgoing EM radiation may be improved as a consequence of improving the uniformity of the incoming EM radiation. 
     In general, devices making use of UV or near UV light need to be designed to ensure eye safety. Various embodiments of the present disclosure address eye safety needs. In preferred embodiments the cumulative power and spectral output of the one or more emitters is intrinsically eye-safe. In some embodiments, an emitter may produce polarized light having an angle of incidence with respect to the substrate in which or on which the photo-luminescent pigment is located. When the polarized incoming EM radiation arrives at the substrate with an angle of incidence equal to about the Brewster&#39;s angle then very little reflection may be produced. This has the effect of controlling reflections to a very substantial degree at the same time that the incoming EM radiation is transmitted into the substrate with high efficiency. It is noted that the Brewster&#39;s angle in these embodiments is given by a formula involving the index of refraction of the substrate and that of air according to the equation: Brewster&#39;s Angle=arctangent (refractive index of substrate/refractive index of air). 
     Further UV control may be obtained in other embodiments. In an embodiment where an emitter illuminates a photo-luminescent visual element from one side while the visual element is being viewed from the opposite side, a substrate that is at least partially transparent to visible light and at least partially opaque to UV may be interposed between the emitter and the viewer to intercept unwanted UV on its way to the viewer. 
     Embodiments of the present disclosure describe a number of ways in which a photo-luminescent pigment may be coupled with or combined with a substrate suitable for the variety of applications contemplated: a photo-luminescent pigment may be combined with a binder or adhesive for surface application to a suitable transparent or translucent substrate; photo-luminescent pigments having sufficiently high temperature stability may be infused, fused, sintered, or even encapsulated on or in compatible plastic, glass, or glass-like substrates; pigments compatible with plastics, rubber compounds, urethanes, epoxies, may be dispersed, layered, or mixed into such binders thereby creating photo-luminescent composite materials. All of the foregoing methods may be used to create rigid photo-luminescent visual elements capable of supporting their own weight. 
     Turning now to  FIG. 1A , an embodiment of a photo-luminescent display system  2  according to the present disclosure is shown comprising: photo-luminescent visual element  10  receiving, from a remotely located emitter  30 , incoming electromagnetic (EM) radiation  32  at a first wavelength; the photo-luminescent visual element radiating outgoing electromagnetic radiation  40  at a second wavelength in response to receiving said incoming EM radiation; emitter  30  producing said incoming EM radiation such that at least a portion of said photo-luminescent visual element  10  is illuminated; said first wavelength located outside of the visible spectrum; said second wavelength located in the visible spectrum; and said emitter further characterized in that it is located remotely from said photo-luminescent visual element. The outgoing EM radiation may comprise an obverse portion  42  and a reverse portion  44 , both portions emanating from the photo-luminescent visual element and traveling in different directions. The visual content of photo-luminescent visual element  10  can be viewed from both sides of the element. 
     Shown in  FIG. 1B  is a cross section of the photo-luminescent visual element and emitter of  FIG. 1A . An embodiment of a photo-luminescent visual element  10  is shown comprising a photo-luminescent pigment  11  coupled to a substrate  20 . Emitter  30  produces incoming EM radiation  32  at a first wavelength, at least a portion of which is absorbed by said photo-luminescent pigment  11  and then radiated as an outgoing EM radiation  40  at a second wavelength. An obverse portion  42  of outgoing EM radiation  40  passes through substrate  20 , while a reverse portion  44  of outgoing EM radiation  40  does not pass through the substrate. In preferred embodiments, said first wavelength is outside the visible spectrum while said second wavelength is within the visible spectrum. Preferred embodiments of photo-luminescent visual element  10  use substrate materials that are substantially transparent to said second wavelength, such as glass or acrylic. Effectively thin or dispersed applications of photo-luminescent pigment  11  create the benefit that the energy contents of said obverse portion and said reverse portion differ from each other by no more than about 30%. This produces an impression of nearly equal radiance of obverse and reverse portions in the eye of the viewer and may be highly desirable in some applications. 
     The difference between said obverse portion and said reverse portion may also be characterized in terms of a least noticeable difference in intensity as judged by the human eye. The least noticeable difference may be defined in a ratio-metric way as the quotient (difference in intensity)/(absolute intensity of the obverse portion). Depending on the individual viewing the photo-luminescent visual element, the least noticeable difference between the obverse portion and the reverse portion may be about 20% or less, in other applications it may be about 10% or less, and in still other applications it may be about 5% or less. 
       FIG. 2A  shows an embodiment similar to that shown in  FIG. 1A , differing in the placement of the remote emitter.  FIG. 1A  and  FIG. 2A  taken together show that embodiments of the present disclosure comprise photo-luminescent visual elements that can be illuminated at a first wavelength by an emitter remotely positioned in any one of a variety of placements and that the subsequent photo-luminescent visual elements can then be viewed at a second wavelength from many different angles. 
     Shown in  FIG. 2B  is a cross section of the photo-luminescent visual element and emitter of  FIG. 2A . An embodiment of a photo-luminescent visual element  10  is shown comprising a photo-luminescent pigment  11  coupled to a substrate  20 . Emitter  30  produces incoming EM radiation  32  at a first wavelength, at least a portion of which is absorbed by said photo-luminescent pigment  11  and then radiated as an outgoing EM radiation  40  at a second wavelength. An obverse portion  42  of outgoing EM radiation  40  passes through substrate  20 , while a reverse portion  44  of outgoing EM radiation  40  does not pass through the substrate. In preferred embodiments, first wavelength is outside the visible spectrum while the second wavelength is with the visible spectrum. Preferred embodiments of photo-luminescent visual element  10  use substrate materials that are substantially transparent to said second wavelength, such as glass or acrylic. Effectively thin or dispersed applications of photo-luminescent pigment  11  create the benefit that the energy contents of said obverse portion and said reverse portion differ from each other by no more than about the least noticeable difference. This produces an impression of nearly equal radiance of obverse and reverse portions in the eye of the viewer. 
     Turning now to  FIG. 3 , shown is a schematic cross section view according to another embodiment of the present disclosure having more than one emitter. An embodiment of a photo-luminescent display system  2  according to the present disclosure is shown comprising: a remotely located first emitter  30   a  radiating a first incoming electromagnetic (EM) radiation  32   a  at a first wavelength; a remotely located second emitter  30   b  radiating a second incoming EM radiation  32   b  at said first wavelength; a photo-luminescent visual element  10  receiving at least a portion of said first incoming EM radiation  32   a  or at least a portion of said second incoming EM radiation  32   b , the photo-luminescent visual element radiating outgoing EM radiation  40  at a second wavelength in response to receiving either of said first incoming EM radiation  32   a  or said second incoming EM radiation  32   b ; first emitter  30   a  producing said first incoming EM radiation  32   a  such that at least a portion of said photo-luminescent visual element  10  is illuminated; second emitter  30   b  producing said second incoming EM radiation  32   b  such that at least a portion of said photo-luminescent visual element  10  is illuminated; said first wavelength located outside of the visible spectrum; said second wavelength located within the visible spectrum; said first emitter  30   a  further characterized in that it is located remotely from said photo-luminescent visual element; said second emitter  30   b  further characterized in that it is located remotely from said photo-luminescent visual element. The outgoing EM radiation may comprise an obverse portion and a reverse portion, both portions emanating from the photo-luminescent visual element and traveling in different directions. 
     Turning now to  FIG. 4 , shown is a cross sectional schematic view according to another embodiment of the present disclosure in which a photo-luminescent visual element has one or more photo-luminescent regions. An embodiment of a photo-luminescent display system  2  according to the present disclosure is shown comprising: a remotely located emitter  30  producing an incoming EM radiation  32  at a first wavelength directed towards a photo-luminescent visual element  10 ; said photo-luminescent visual element  10  comprising: a first photo-luminescent region  12   a  coupled to a substrate  20 ; a second photo-luminescent region  12   b  coupled to said substrate; wherein said first photo-luminescent region  12   a  receives a portion of incoming EM radiation  32  and produces first outgoing EM radiation  40   a  at a second wavelength; and wherein said second photo-luminescent region  12   b  receives a portion of incoming EM radiation  32  and produces a second outgoing EM radiation  40   b  at a third wavelength. Said second and said third wavelengths may be the same or different wavelengths, both within the human visual spectrum. 
     In consideration of the embodiments of  FIG. 3  and  FIG. 4 , it is within the spirit and scope of the present disclosure to create an embodiment having multiple emitters radiating towards multiple photo-luminescent elements. Furthermore, different photo-luminescent regions may produce outgoing EM radiation at different wavelengths thereby enabling display systems with a spectrum of color characteristics. A plurality of photo-luminescent regions may be used in which a plurality of photo-luminescent pigments radiate at a plurality of wavelengths. The plurality of photo-luminescent regions may also vary in size, thereby providing a wide range of visual effects. 
     Shown now in  FIG. 5  is a system  2  comprising a remotely located emitter  30  producing an incoming EM radiation  32  at a first wavelength and directed toward a photo-luminescent element  10 , said photo-luminescent element  10  comprising: a photo-luminescent pigment  11  disposed between a first substrate  20   a  and a second substrate  20   b ; the photo-luminescent pigment operative to radiate an outgoing EM radiation  40  at a second wavelength; said outgoing EM radiation comprising both an obverse portion  42  passing through first substrate  20   a  and a reverse portion  44  passing through second substrate  20   b.    
     The system of  FIG. 5  has a number of advantages. Some photo-luminescent pigments may be sensitive to environmental conditions such as temperature, humidity, oxygen, etc. By encapsulating photo-luminescent pigment between two substrates the impact of environmental factors on the operational characteristics and lifetime on the photo-luminescent visual element may be reduced. 
     Further advantages may be realized from the embodiment of  FIG. 5 . The substrate that incoming EM radiation at the first wavelength passes through on its way to the photo-luminescent pigment may be selected to substantially pass the first wavelength while the other substrate may be selected to substantially block the first wavelength. Such a configuration has the advantage of blocking most of the energy at the first wavelength that would otherwise pass through the other substrate. In embodiments where the first wavelength is in the UV portion of the spectrum, it may be beneficial to block the transmission through the other substrate of at least a portion of the UV light that was not absorbed by the photo-luminescent pigment. Use of a UV blocking substrate between the photo-luminescent pigment and a viewer may enhance the eye-safety of the system by blocking a portion of the unabsorbed incoming EM radiation that is in the UV band. 
     With continuing reference to  FIG. 5 , a sufficiently thin or dispersed layer of photo-luminescent pigment may be used such that the layer appears substantially transparent to wavelengths in the visible spectrum. When exposed to incoming EM radiation at the first wavelength such a layer will radiate at the second wavelength and hence become visible. A variety of eye-catching and useful transparent and semi transparent effects may be produced. 
       FIG. 6  shows an embodiment similar to the system of  FIG. 5 . The embodiment of  FIG. 6  is further characterized in that second substrate  20   b  has a planar surface  25  disposed to receive, at an angle of incidence  31 , a polarized incoming EM radiation  34  at a first wavelength. Remotely located emitter  30  produces said polarized incoming EM radiation  34 , directing it towards said planar surface  25  at said angle of incidence  31 . In preferred embodiments, the direction of polarization and the angle of incidence may be coordinated such that said incoming EM radiation  34  arrives at said planar surface  25  at about the Brewster&#39;s angle and produces substantially no reflection of the first wavelength from planar surface  25 . When polarized and directed in the described way, reflections from said planar surface may be minimized. Such an arrangement may be used to enhance eye-safety by controlling reflections of the first wavelength from said planar surface. 
     Turning now to  FIG. 7 , shown is a cross sectional schematic view according to another embodiment of the present disclosure in which a photo-luminescent visual element  10  comprises a photo-luminescent pigment dispersed in a binder  13 , the composite being sufficiently rigid to maintain its shape under the force of gravity. Emitter  30  produces a incoming EM radiation  34  at a first wavelength that is directed toward said photo-luminescent pigment dispersed in a binder  13  with an angle of incidence  31 . The photo-luminescent pigment produces an outgoing EM radiation  40  at a second wavelength, transmitting a reverse portion through a first planar surface  25   a  and an obverse portion through a second planar surface  25   b . In preferred embodiments, the direction of polarization and the angle of incidence may be coordinated such that said incoming EM radiation  34  arrives at said first planar surface  25   a  at about the Brewster&#39;s angle and produces substantially no reflection of the first wavelength from first planar surface  25   a.    
     Depending upon the effect desired, the photo-luminescent pigment in the embodiment of  FIG. 7  may be dispersed throughout the majority of the binder or it may be dispersed through only a portion of the binder. The binder is at least partially transparent to the first wavelength and at least partially transparent to the second wavelength. 
     With reference now to  FIG. 8 , shown is another embodiment of a photo-luminescent display system comprising: an emitter  30  producing an incoming EM radiation  34  directed toward a photo-luminescent visual element  10  comprising: a planar substrate  24  having both a pigment side  26  and a viewing side  28 ; and, a photo-luminescent pigment  11  fused to said pigment side. Photo-luminescent pigment  11  may be a material chosen to survive elevated temperatures required for fusing it to the pigment side of the substrate. Substrate materials may include glass and acrylic. 
       FIG. 9A  shows a perspective view of another photo-luminescent display system according to the present disclosure. A photo-luminescent display system  2  according to an embodiment of the present disclosure comprises: an emitter  30  producing an incoming electromagnetic (EM) radiation  32  at a first wavelength outside of the visual spectrum, emitter  30  being optically coupled to a photo-luminescent visual element  10 . Photo-luminescent visual element  10  is shown comprising: a planar substrate  24  having at least one substrate edge  27  adapted to accept said incoming EM radiation  32 . Photo-luminescent visual element  10  produces an outgoing EM radiation  40  having an obverse portion  42  and a reverse portion  44 . 
     More detail is visible in cross sectional view  FIG. 9B , which shows photo-luminescent visual element  10  comprising a plurality of photo-luminescent regions  12   a ,  12   b ,  12   c ,  12   d , and  12   e  in direct contact with said planar substrate  24  in which each photo-luminescent region receives a portion of said incoming EM radiation  32  and in which each photo-luminescent region produces by means of photo-luminescence an outgoing EM radiation  40  having a wavelength within the visible spectrum. Incoming EM radiation  32  is distributed throughout planar substrate  24  by means of the optical phenomenon of total internal reflection, mainly exiting the planar substrate at the locations in direct contact with any of the plurality of photo-luminescent regions. Each photo-luminescent region thereby receives a portion of incoming EM radiation  32  and then emits outgoing EM radiation at another wavelength by means of photo-luminescence. 
       FIG. 9C  shows an enlarged view, corresponding to  FIG. 9A , of a plurality of photo-luminescent regions  12   a ,  12   b ,  12   c ,  12   d , and  12   e  in contact with planar substrate  24 . It is noted that many or few photo-luminescent regions may be used, depending on the subject matter displayed. Furthermore the plurality of photo-luminescent regions may vary in size, position, and composition of photo-luminescent pigment such that different colors and intensities may be produced. In preferred embodiments the size and density of photo-luminescent regions may vary in a predetermined way to create an impression of nearly uniform brightness across the entire photo-luminescent visual element. Due to the logarithmic sensitivity of the human eye, brightness variations of about less than 20% may appear to be nearly uniformly bright. In other preferred embodiments, the geometry and intensity of the emission pattern produced by the emitter may be taken into account when designing a pattern of photo-luminescent regions, thereby creating desirable visual properties for the entire system. In other embodiments, brightness variations of about 10% or less appear to uniformly bright, and in still other embodiments brightness variations of about 5% or less appear to uniformly bright. 
     Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. It may be desirable to combine features shown in various embodiments into a single embodiment. A different number and configuration of features may be used to construct embodiments of photo-luminescent display systems and photo-luminescent visual elements that are entirely within the spirit and scope of the present disclosure. Therefor, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. 
     Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. Section 112, Paragraph 6. In particular, the use of “step of” in the claims herein is not intended to invoke the provisions of 35 U.S.C. Section 112, Paragraph 6.