Abstract:
A system and method for producing a conformal electroluminescent coating on an object wherein an electrically conductive base backplane film layer is applied upon a substrate. One or more intermediate layers, such as dielectric, or phosphor film layers, is/are applied upon the conductive backplane film layer. An electrode film layer is applied upon the one or more intermediate layers using a substantially transparent, electrically conductive material. The electroluminescent phosphor is excitable by an electrical field established across the phosphor film layer such that the device emits electroluminescent light upon application of an electrical charge between the conductive backplane film layer and the electrode film layer.

Description:
This application is continuation-in-part of U.S. patent application Ser. No. 14/736,936, filed Jun. 11, 2015, the entire content of this application being hereby incorporated by reference as if fully rewritten herein. 
    
    
     FIELD 
     The present invention relates to a process for producing electroluminescent systems having a lower backplane electrode layer and an upper electrode layer, the lower and upper electrode layers being connectable to an electrical driving circuit. One or more functional layers are disposed between the lower and upper electrode layers to form at least one electroluminescent area. 
     BACKGROUND 
     Since the 1980s, electroluminescent (EL) technology has come into widespread use in display devices where its relatively low power consumption, relative brightness and ability to be formed in relatively thin-film configurations have shown it to be preferable to light emitting diodes (LEDs) and incandescent technologies for many applications. 
     Commercially manufactured EL devices have traditionally been produced using doctor blade coating and printing processes such as screen printing or, more recently, ink jet printing. For applications that require relatively planar EL devices these processes have worked reasonably well, as they lend themselves to high-volume production with relatively efficient and reliable quality control. 
     However, traditional processes are inherently self-limiting for applications where it is desirable to apply an EL device to a surface having complex contoured topologies, such as convex, concave and reflexed surfaces. Partial solutions have been developed wherein a relatively thin-film EL decal is applied to a surface, the decal being subsequently encapsulated within a polymer matrix. While moderately successful, this type of solution has several inherent weaknesses. Firstly, while decals can acceptably conform to mild concave/convex topologies, they are incapable of conforming to tight-radius curves without stretching or wrinkling. In addition, the decal itself does not form either a chemical or mechanical bond with an encapsulating polymer, essentially remaining a foreign object embedded within the encapsulating matrix. These weaknesses pose difficulties in both manufacturing and product life-cycle, as embedded-decal EL lamps applied to complex topologies are difficult to produce and are susceptible to delamination arising from mechanical stresses, thermal stresses and long-term exposure to ultraviolet (UV) light. 
     SUMMARY 
     A process is disclosed according to an embodiment of the present invention whereby an EL device is “painted” onto a surface, i.e., substrate, of a target item to which the EL device is to be applied. The present invention is applied to the substrate in a series of layers, with each layer performing a specific function. 
     In the various embodiments described herein, a spray-applied conformal coating comprises the following components, included in the various layers in differing amounts as disclosed herein: a conductive component, a reducer solvent component to assist in the deposition and post-deposition flow, a high-dielectric pigment component, an electroluminescent pigment component, and a film-forming binder component that forms a film that flows evenly and consistently when atomized onto the surface of an object; the various components being sometimes described in conjunction with a layer (e.g. outer layer conductive component); 
     One embodiment comprises an inherently conductive and substantially transparent outer layer comprising the conductive component, the reducer solvent component, and the binder component; an inherently conductive inner layer comprising the reducer solvent component, the binder component, and the conductive component; a first intermediate layer, being disposed between the inner and outer layers, and further comprising, the reducer solvent component, the binder component, and the high-dielectric pigment component, said first intermediate layer being adapted to insulate said outer layer from said inner layer, where the film flows to a smooth film that completely covers the inner layer so as not to allow a direct electrical connection between conductive layers; and a second intermediate layer, being disposed between the inner and outer layers, and further comprising the reducer solvent component, the binder component, the electroluminescent pigment component, said second intermediate layer being adapted to flow after deposition in a manner where the electroluminescent pigment is dispersed in an even and uniform layer as the film cures to provide a uniform lighting effect when energized. 
     In one embodiment, a spray-applied conformal coating comprises an inherently conductive and substantially transparent outer layer; an inherently conductive inner layer; a first intermediate layer, being disposed between the inner and outer layers; and a second intermediate layer, being disposed between the inner and outer layers. 
     The inherently conductive and substantially transparent outer layer comprises 2-12% by weight of an inherently conductive polymer component, such as PEDOT:PSS or other inherently conductive polymer, typically 3%-5%; 55-80% by weight of a reducer solvent component, typically 70-75%, to assist in the deposition and post-deposition flow of the outer layer, with said reducer solvent being functionally compatible with the chosen binder system and, potentially, the inherently conductive polymer, and the reducer component including any one or more of toluene, xylene, acetone, naphtha, mineral spirits, methyl ethyl ketone, acetone, water, ethanol, isopropyl alcohol, n-butyl alcohol, methanol, ethyl benzene, cumene, Solane, n-propyl acetate, methyl acetate, methyl cyclohexane, p-Trifluoromethylphenyl chloride, and p-Chlorobenzotrifluoride, or other volatile solvent, typically in the ratio of 15-%30% by weight ethanol, 15-25% by weight methyl acetate, 15-25% by weight p-Chlorobenzotrifluoride, and 15-25% by weight water; and 10-30% by weight of a film-forming binder component, preferably 10-15%, which is compatible with the inherently conductive polymer and forms a film that flows evenly and consistently when atomized onto the surface of an object, with said binder component including any one or more of an acrylic, polyurethane, vinyl, latex, cellulose acetate butyrate or other binder, preferably a polyurethane or acrylic. The outer layer has a thickness in the range of 0.0002″ to 0.0006″, typically 0.0005″, and a resistivity of less than 2000 ohm/square meter. 
     The inherently conductive inner layer comprises 40-75% by weight of said reducer solvent component, typically 55%-65%, with the reducer solvent being typically either 50-70% n-butyl acetate and 30-50% xylene or 50-70% methyl acetate and 30-50% xylene; 20-35% by weight of said binder component, typically 20-25%, and preferably an acrylic or polyurethane binder; 20-50% by weight of a conductive pigment component, typically 30%-40%, where said conductive pigment component includes any one or more of silver flakes, silver nanowire, silver nanoparticles, copper flakes, copper nanowire, copper nanoparticles, nickel flakes, nickel nanowire, nickel nanoparticles, silver-coated copper flakes, silver-coated copper nanowire, carbon nanotubes, graphene, metal-coated particles, or other inherently conductive particles, typically silver flakes or silver-coated copper flakes. The inner layer has a thickness in the range of 0.0005″ to 0.002″, typically 0.001″, and a resistivity of less than 20 ohm/square meter. 
     The first intermediate layer is disposed between the inner and outer layers, and further comprises 45-80% by weight of said reducer solvent component, typically 60%-65%, with the reducer solvent being typically either 50-70% n-butyl acetate and 30-50% xylene or 50-70% methyl acetate and 30-50% xylene; 10-35% by weight of said binder component, typically 15-20%, and preferably an acrylic or polyurethane binder; 20-50% by weight of a high-dielectric pigment component, typically 35%-45%, with said high-dielectric pigment component including any one or more of barium titanate, strontium titanate, titanium dioxide, lead zirconate titanate, tantalum oxide, aluminum oxide, or other high-dielectric solids. The first intermediate layer has a thickness in the range of 0.0005″ to 0.002″, typically 0.001″, and is adapted to insulate said outer layer from said inner layer, where the film flows to a smooth film that completely covers the inner layer so as not to allow a direct electrical connection between conductive layers. 
     The second intermediate layer is disposed between the inner and outer layers, and further comprises 40-80% by weight of said reducer solvent component, typically 60%-65%, with the reducer solvent being typically either 50-70% n-butyl acetate and 30-50% xylene or 50-70% methyl acetate and 30-50% xylene; 10-35% by weight of said binder component, typically 15-20%, and preferably an acrylic or polyurethane binder; 20-50% by weight of an electroluminescent pigment component, typically 35%-45%, with said electroluminescent pigment component including any one or more of metal-doped zinc sulfide phosphors, metal-doped zinc selenide phosphors, metal-doped or native crystalline oxides such as Ga2O3, ZnGa2O4, CaGa2O4, Zn2SiO7, Zn2SiO4, Y2SIO5, and oxide phosphors of Sr, Ga, Ba, and Eu in some combination, or other electroluminescent phosphors. The electroluminescent pigment component has a thickness in the range of 0.001″ to 0.003″, typically 0.002″, and is adapted to flow after deposition in a manner where the electroluminescent pigment is dispersed in an even and uniform layer as the film cures to provide a uniform lighting effect when energized. 
     In one embodiment, the outer layer transparent conductive component comprises said conductive pigment component, and has a thickness in the range of 0.001″ to 0.002″, and a resistivity of less than 100 ohm/square meter. 
     In one embodiment, the inner layer conductive component comprises an inherently conductive polymer, such as PEDOT:PSS or other inherently conductive polymer, and has a thickness in the range of 0.0002″ to 0.001″, and a resistivity of less than 2000 ohm/square meter. 
     In one embodiment, the first intermediate layer is disposed between said inner layer and said second intermediate layer, and said second intermediate layer is disposed between said outer layer and said first intermediate layer. 
     In one embodiment said first intermediate layer being and said second intermediate layer are blended into the same layer (a combined intermediate layer) and sprayed simultaneously, wherein said combined intermediate layer comprises, 40-80% by weight of said reducer solvent component, typically 60%-65%, with the reducer solvent being typically either 50-70% n-butyl acetate and 30-50% xylene or 50-70% methyl acetate and 30-50% xylene; 10-35% by weight of said binder component, typically 15-20%, and preferably an acrylic or polyurethane binder; 10-30% by weight of an electroluminescent pigment component, typically 15%-25%; 10-25% by weight of a high-dielectric pigment component, typically 15%-20%; and has a thickness in the range of 0.002″ to 0.004″, typically 0.002″; the combined intermediate layer being adapted to flow after deposition in a manner where the electroluminescent pigment is dispersed in an even and uniform layer as the film cures to provide a uniform lighting effect when energized, and where the film flows to a smooth film that completely covers the inner layer so as not to allow a direct electrical connection between conductive layers. 
     In one embodiment, the spray-applied conformal coating is applied by high pressure low volume spray techniques, where each coating is atomized by compressed air and deposited on the conformal substrate in this manner, and the coating then flows after deposition to the proper film thickness. 
     In one embodiment, the spray-applied conformal coating is applied by aerosol spray techniques, where each coating is atomized by a propellant inside the can, typically propane, and deposited on the conformal substrate in this manner, and the coating then flows after deposition to the proper film thickness. 
     In one embodiment, the spray-applied conformal coating is applied by electrostatic spray techniques, where each coating is atomized by compressed air and deposited on the charged surface of the conformal substrate in this manner, and the coating then flows after deposition to the proper film thickness. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features of the inventive embodiments will become apparent to those skilled in the art to which the embodiments relate from reading the specification and claims with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic layer diagram of an EL lamp according to one embodiment of the present invention. 
         FIG. 2  is a schematic layer diagram of an EL lamp according to another embodiment of the present invention. 
         FIG. 3  is a schematic layer diagram of an EL lamp according to yet another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the discussion that follows, like reference numerals are used to refer to like elements and structures in the various figures. Also, the terms “transparent” and “clear” generally refer to a layered material&#39;s ability to allow light to pass through without significant absorption and includes translucent characteristics. For the purpose of discussion, as used herein the terms “film”, “layer” and “coating” are used interchangeably to describe an applied layer of material in an EL device. 
     While this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that changes in form and detail thereof may be made without departing from the scope of the claims of the inventions. 
     In one embodiment, a spray-applied conformal coating  920  comprises, inherently conductive and substantially transparent outer layer  460  comprising 2-12% by weight of an outer layer conductive component, 55-80% by weight of a reducer solvent component to assist in the deposition and post-deposition flow of outer layer  460  and 10-30% by weight of a film-forming binder component that forms a film that flows evenly and consistently when atomized onto the surface of an object; an inherently conductive inner layer  400  comprising 40-75% by weight of the reducer solvent component, 20-35% by weight of the binder component, 20-50% by weight of an inner layer conductive component; a first intermediate layer  420 , being disposed between the inner and outer layers  400 ,  460 , and further comprising, 45-80% by weight of the reducer solvent component, 10-35% by weight of the binder component, 20-50% by weight of a high-dielectric pigment component, the high-dielectric pigment component, the first intermediate layer  420  being adapted to insulate the outer layer  460  from the inner layer  400 , where the film flows to a smooth film that completely covers inner layer  400  so as not to allow a direct electrical connection between conductive layers  400 ,  460 ; a second intermediate layer  440 , being disposed between the inner and outer layers  400 ,  460 , and further comprising 40-80% by weight of the reducer solvent component, 10-35% by weight of the binder component, 20-50% by weight of an electroluminescent pigment component, the second intermediate layer  460  being adapted to flow after deposition in a manner where the electroluminescent pigment is dispersed in an even and uniform layer as the film cures to provide a uniform lighting effect when energized. 
     In one embodiment, a spray-applied conformal coating  920  comprises, inherently conductive and substantially transparent outer layer  460  comprising 2-12% by weight of an outer layer conductive component, 55-80% by weight of a reducer solvent component to assist in the deposition and post-deposition flow of outer layer  460 , the reducer solvent component including any one or more of, toluene, xylene, acetone, naphtha, mineral spirits, methyl ethyl ketone, acetone, water, ethanol, isopropyl alcohol, n-butyl alcohol, methanol, ethyl benzene, cumene, Solane, n-propyl acetate, methyl acetate, methyl cyclohexane, p-Trifluoromethylphenyl chloride, and p-Chlorobenzotrifluoride, or other volatile solvent, typically in the ratio of 15-%30% by weight ethanol, 15-25% by weight methyl acetate, 15-25% by weight p-Chlorobenzotrifluoride, and 15-25% by weight water and 10-30% by weight of a film-forming binder component that forms a film that flows evenly and consistently when atomized onto the surface of an object, outer layer  460  having a thickness in the range of 0.0002″ to 0.0006″, outer layer  460  having a resistivity of less than 2000 ohm/square meter; inherently conductive inner layer  400  comprises 40-75% by weight of the reducer solvent component, 20-35% by weight of the binder component, 20-50% by weight of an inner layer conductive component inner layer  400  having a thickness in the range of 0.0005″ to 0.002″; outer layer  460  having a resistivity of less than 20 ohm/square meter; first intermediate layer  420 , is disposed between inner and outer layers  400 ,  460 , and further comprises 45-80% by weight of the reducer solvent component, 10-35% by weight of the binder component, 20-50% by weight of a high-dielectric pigment component, the high-dielectric pigment component including any one or more of barium titanate, strontium titanate, titanium dioxide, lead zirconate titanate, tantalum oxide, aluminum oxide, or other high-dielectric solids, first intermediate layer  420  having a thickness in the range of 0.0005″ to 0.002″, first intermediate layer  420  is adapted to insulate outer layer  460  from inner layer  400 , where the film flows to a smooth film that completely covers the inner layer so as not to allow a direct electrical connection between conductive layers  400 ,  460 ; second intermediate layer  440 , is disposed between inner and outer layers  400 ,  460 , and further comprises 40-80% by weight of the reducer solvent component, 10-35% by weight of the binder component, 20-50% by weight of an electroluminescent pigment component, the electroluminescent pigment component including any one or more of metal-doped zinc sulfide phosphors, metal-doped zinc selenide phosphors, metal-doped or native crystalline oxides such as Ga2O3, ZnGa2O4, CaGa2O4, Zn2SiO7, Zn2SiO4, Y2SIO5, and oxide phosphors of Sr, Ga, Ba, and Eu in some combination, or other electroluminescent phosphors, second intermediate layer  440  is adapted to flow after deposition in a manner where the electroluminescent pigment is dispersed in an even and uniform layer as the film cures to provide a uniform lighting effect when energized. 
     In one embodiment, the outer layer conductive component comprises a conductive pigment component; the inner layer conductive component comprises an inherently conductive polymer component. 
     In one embodiment, the inherently conductive polymer component comprises PEDOT:PSS; the conductive pigment component includes any one or more of silver flakes, silver nanowire, silver nanoparticles, copper flakes, copper nanowire, copper nanoparticles, nickel flakes, nickel nanowire, nickel nanoparticles, silver-coated copper flakes, silver-coated copper nanowire, carbon nanotubes, graphene, metal-coated particles, or other inherently conductive particles, typically silver flakes or silver-coated copper flakes. 
     In one embodiment, the outer layer conductive component comprises an inherently conductive polymer component; the inner layer conductive component comprises a conductive pigment component. 
     In one embodiment, the inherently conductive polymer component comprises PEDOT:PSS; the conductive pigment component includes any one or more of silver flakes, silver nanowire, silver nanoparticles, copper flakes, copper nanowire, copper nanoparticles, nickel flakes, nickel nanowire, nickel nanoparticles, silver-coated copper flakes, silver-coated copper nanowire, carbon nanotubes, graphene, metal-coated particles, or other inherently conductive particles, typically silver flakes or silver-coated copper flakes. 
     In one embodiment, the film-forming binder component is compatible with an inherently conductive polymer component; the reducer solvent component is functionally compatible with, the film-forming binder component, and the inherently conductive polymer component. 
     In one embodiment, outer layer  460  further comprises 3%-5% by weight of the outer layer conductive component. 
     In one embodiment, outer layer further  460  comprises 70-75% by weight of the reducer solvent component. 
     In one embodiment, the binder component of outer layer  460  including any one or more of an acrylic, polyurethane, vinyl, latex, cellulose acetate butyrate or other binder, preferably a polyurethane or acrylic. 
     In one embodiment, outer layer  460  further comprises 10-15% by weight of the film-forming binder component. 
     In one embodiment, outer layer  460  has a thickness of substantially 0.0005″. 
     In one embodiment, the reducer solvent component of inner layer  400  further comprises 50-70% n-butyl acetate and 30-50% xylene. 
     In one embodiment, the reducer solvent component of inner layer  400  further comprises or 50-70% methyl acetate and 30-50% xylene. 
     In one embodiment, inherently conductive inner layer  400  further comprises 55%-65% by weight of the reducer solvent component. 
     In one embodiment, inner layer  400  further comprises 20-25% by weight of the binder component. 
     In one embodiment, the binder component of inner layer  400  further comprises an acrylic. 
     In one embodiment, the binder component of inner layer  400  further comprises a polyurethane. 
     In one embodiment, inner layer  400  further comprises 30%-40% by weight of the inner layer conductive component. 
     In one embodiment, inner layer  400  has a thickness of substantially 0.001″. 
     In one embodiment, the reducer solvent component of first intermediate layer  420  is 50-70% n-butyl acetate and 30-50% xylene. 
     In one embodiment, the reducer solvent component of first intermediate layer  420  is 50-70% methyl acetate and 30-50% xylene. 
     In one embodiment, first intermediate layer  420  further comprises 60%-65% by weight of the reducer solvent component. 
     In one embodiment, first intermediate layer  420  further comprises 15-20% by weight of the binder component. 
     In one embodiment, the binder component of first intermediate layer  420  is acrylic. 
     In one embodiment, the binder component of first intermediate layer  420  is polyurethane. 
     In one embodiment, first intermediate layer  420  further comprises 35%-45% by weight of the high-dielectric pigment component. 
     In one embodiment, first intermediate layer  420  has a thickness of substantially 0.001″. 
     In one embodiment, the reducer solvent component of second intermediate layer  440  is 50-70% n-butyl acetate and 30-50% xylene. 
     In one embodiment, the reducer solvent component of second intermediate layer  440  is 50-70% methyl acetate and 30-50% xylene. 
     In one embodiment, second intermediate layer  440  further comprises 60%-65% by weight of the reducer solvent component. 
     In one embodiment, second intermediate layer  440  further comprises 15-20% by weight of the binder component. 
     In one embodiment, the binder component of second intermediate layer  440  is an acrylic. 
     In one embodiment, the binder component of second intermediate layer  440  is a polyurethane. 
     In one embodiment, second intermediate layer  440  further comprises 35%-45% by weight of an electroluminescent pigment component. 
     In one embodiment, the electroluminescent pigment component has a thickness of substantially 0.002″. 
     In one embodiment, the electroluminescent pigment component of second intermediate layer  440  has a thickness of substantially 0.002″. 
     In one embodiment, outer layer  460  has a thickness in the range of 0.001″ to 0.002″ outer layer  460  has a resistivity of less than 100 ohm/square meter. 
     In one embodiment, inner layer  400  has a thickness in the range of 0.0002″ to 0.001″ inner layer  400  has a resistivity of less than 2000 ohm/square meter. 
     In one embodiment ( FIG. 1 ), first intermediate layer  420  is disposed between inner layer  400  and second intermediate layer  440 , and second intermediate layer  440  is disposed between outer layer  460  and first intermediate layer  420 . 
     In one embodiment ( FIG. 3 ), first intermediate layer  420  and second intermediate layer  440  are blended into combined intermediate layer  441  and sprayed simultaneously; combined intermediate layer  441  comprises, 40-80% by weight of the reducer solvent component, 10-35% by weight of the binder component, 10-30% by weight of an electroluminescent pigment component, 10-25% by weight of a high-dielectric pigment component, combined intermediate layer  441  has a thickness in the range of 0.002″ to 0.004″, combined intermediate layer  441  is adapted to flow after deposition in a manner where the electroluminescent pigment is dispersed in an even and uniform layer as the film cures to provide a uniform lighting effect when energized, and where the film flows to a smooth film that completely covers inner layer  400  so as not to allow a direct electrical connection between conductive layers  400  &amp;  460 . 
     In one embodiment, the reducer solvent component is 50-70% n-butyl acetate and 30-50% xylene. 
     In one embodiment, the reducer solvent component is 50-70% methyl acetate and 30-50% xylene. 
     In one embodiment, combined intermediate layer  441  comprises 60%-65% by weight of the reducer solvent component. 
     In one embodiment, combined intermediate layer  441  comprises 15-20% by weight of the reducer solvent component. 
     In one embodiment, the reducer solvent component of combined intermediate layer  441  comprises an acrylic. 
     In one embodiment, the reducer solvent component of combined intermediate layer  441  comprises a polyurethane binder. 
     In one embodiment, combined intermediate layer  441  comprises 15%-25% by weight of an electroluminescent pigment component. 
     In one embodiment, combined intermediate layer  441  comprises 15%-20% by weight of a high-dielectric pigment component. 
     In one embodiment, combined intermediate layer  441  has a thickness of substantially 0.002″. 
     In one embodiment, the various layers are applied by High Pressure Low Volume spray techniques, wherein each coating is atomized by compressed air and deposited on the conformal substrate in this manner, and the coating then flows after deposition to the proper film thickness. 
     In one embodiment, the various layers are applied by aerosol spray techniques, wherein each coating is atomized by a propellant inside of a can, and deposited on the conformal substrate in this manner, and the coating then flows after deposition to the proper film thickness. 
     In one embodiment, the propellant inside of the can comprises propane. 
     In one embodiment, the various layers are applied by electrostatic spray techniques, where each coating is atomized by compressed air and deposited on the charged surface of the conformal substrate in this manner, and the coating then flows after deposition to the proper film thickness.