Abstract:
The microstructure non-thermal visible light source may emit visible light. A microstructure element may be filled with a gas and may be disposed in a light transparent dielectric binder positioned between two spaced apart electrical conductors. An electrical source may be in electrical communication with the electrical conductors for the electrical source to transmit a signal to the electrical conductors to excite the gas to cause an electron in a plurality of gas molecules to transition to higher energy states. The higher energy states may be metastable and the higher energy states may decay with the emission of a photon at selected wavelengths.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of Provisional Application No. 60/709,354, filed on Aug. 18, 2005 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates to devices that produce visible light for illumination, display and the like. The new device may have microstructure elements filled with a gas that may be excited by an electric field to produce a desired color of light or a spectrum of white light.  
         [0003]     Various light sources have been disclosed that may be formed of small devices, such as, solid state semiconductor devices, ceramic and polymer material devices similar to LED&#39;s, and electrodes in a gas enclosure. Some of these devices are non-thermal light emitting sources such as a solid state semiconductor device or a microdischarge device having electrodes imbedded in a gas enclosure while others may have thermal emission light characteristics such as a miniature incandescent light bulb. The various light source devices may produce poor spectral quality illumination as for example semiconductor devices may have good spectral control, but lack high intensity. Also, fabrication costs may be relatively high as for example that of semiconductor devices.  
       SUMMARY OF THE INVENTION  
       [0004]     The present invention is directed to devices that may emit visible light. A microstructure element may be filled with a gas and may be disposed in a light transparent dielectric binder positioned between two spaced apart electrical conductors. An electrical source may be in electrical communication with the electrical conductors for the electrical source to transmit a signal to the electrical conductors to excite the gas to cause an electron in a plurality of gas molecules to transition to higher energy states. The higher energy states may be metastable and the higher energy states may decay with the emission of a photon at selected wavelengths.  
         [0005]     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  illustrates a side view of a microstructure visible light source with multiple microstructure elements according to an embodiment of the invention;  
         [0007]      FIG. 2  illustrates a top view of a microstructure visible light source according to an embodiment of the invention;  
         [0008]      FIG. 3  illustrates a side view of a microstructure visible light source member of an array structure according to an embodiment of the invention;  
         [0009]      FIG. 4  illustrates a side view of a microstructure visible light source member of an array structure according to an embodiment of the invention;  
         [0010]      FIG. 5  illustrates a side view of a microstructure visible light source member of an array structure according to an embodiment of the invention;  
         [0011]      FIG. 6  illustrates a top view of a microstructure visible light source array according to an embodiment of the invention;  
         [0012]      FIG. 7  illustrates a top view of a microstructure visible light source array according to an embodiment of the invention;  
         [0013]      FIG. 8  illustrates a top view of a microstructure visible light source array according to an embodiment of the invention;  
         [0014]      FIG. 9  illustrates a perspective view of a relatively thin, flexible curved microstructure visible light source according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]     The following detailed description represents the best currently contemplated modes for carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention.  
         [0016]     Microstructure elements may be filled with a gas that may be excited by an electric field. The electrons in the gas molecules may transition to higher energy states that have been designed to be metastable, that is, have a short lifetime. The molecular energy states decay with the emission of photons at the engineered wavelengths. The specific excited states and emitted wavelengths may be determined by the strength and modulation of the applied electric field, the size and wall composition of a microstructure element and the gas molecules in the microstructure element. These parameters may be controlled to optimize efficiency and tune spectral content and spatial geometry. Each microstructure may be an individual high intensity non-thermal emitter. The color of the emissions may be determined by the excited gas and the specific decay process permitted by the geometry, by electric field and by the material in the binder. The patterns of the emitted light may be controlled by the geometry of the electrodes that are the source of the excitation fields, and the characteristics of the supplied electrical power.  
         [0017]     The microstructure visible light source may emit visible wavelengths directly. No intermediate process may be needed between the excitation of the gases and the emission of the desired wavelengths. This is an energy efficient process.  
         [0018]     Referring to  FIGS. 1 and 2 , a microstructure visible light source  10  may have multiple microstructure elements  12  embedded in a dielectric binder  14  that is sandwiched or disposed between a base conductor  16  and a top conductor  18 . There may be an electrical source  20  connected to the base conductor  16  and top conductor  18  to produce an electric field between the conductors  16 ,  18 . The microstructure elements  12  may be gas filled containers that may be a glass, or other suitable material, microsphere of approximately 20 to 100 microns in diameter that may be filled with nitrogen gas to produce a wide spectral content white light.  
         [0019]     The size of the microstructure elements  12 , that are mesoscopic, may determine the light spectrum and efficiency. The gas in each microstructure element  12  may be nitrogen, argon or other gas to produce a desired color, or may be a mixture of multiple gases to produce the spectral content of emitted light. The microstructure elements  12  may be made of glass or other material that is generally transparent. The microstructure elements  12  may also be coated with material such as phosphorous to produce a particular color effect. While spherical shapes for the microsphere elements  12  are illustrated, other shapes, such as, cylinders, cones, irregular shapes and other geometric shapes may be used. The microsphere elements may be positioned randomly or orderly in the dielectric binder  14 .  
         [0020]     The dielectric binder  14  may have a high dielectric breakdown strength and be transparent in the visual spectrum. The dielectric material may be flexible or stiff and may be selected depending on the particular application. Phosphorous may be added to the dielectric binder  14  to produce a particular color effect.  
         [0021]     The base conductor  16  may range from flexible to rigid and may be formed of metal, metal coated with Kapton, circuit board materials, or titanium sheet material. The base conductor  16  may be relatively thin or thick depending on the application, for example, less than 1 mil to greater than 10 mils, and be a good electrical conductor.  
         [0022]     The top conductor  18  may be electrically conductive and visually transparent to pass emitted light from the microstructure elements  12 . The top conductor  18  may be formed of a substrate material  22  and a conductive coating  24 . The materials may be plastic, glass or other suitable transparent material coated with indium tin oxide that may have approximately 10 to 15 ohms per square inch surface resistance. The resistance value may be a trade between efficiency, cost durability, and spectral intensity and visual content. The top conductor  18  may range from flexible to rigid in structure.  
         [0023]     The electric source  20  may produce an electric field between the conductors  16 ,  18  that may excite the gas in the microstructure elements  12 . Once the gas molecules are in the desired excited state, when they decay, light may be emitted. The electrical source  20  may be a standard power source converted or transformed to produce the desired electrical field between the conductors  16 ,  18 . The voltage, pulse width, and pulse repetition frequency may be adjusted to establish spectral content, efficiency and durability.  
         [0024]     Referring to  FIGS. 3 through 5 , other arrangements of the conductors  16 ,  18  of the microstructure visible light source  10  may be used. For example, the conductors  26  may be located on opposite sides of a dielectric binder  14  having microstructure elements  12  to excite the gas molecules. The emitted light may still be directed to exit the top  28  of the microstructure visible light source  10 . The conductors  26  may also have a geometry from a relatively thin form to a broader structure as illustrated in  FIG. 4 . This may be useful in a fabrication process where the microstructure elements  12  may be formed in an array or in a broad dielectric substrate  15  material. A dielectric substrate  15  may have channels  30  or grooves formed therein in which the dielectric binder  14  with microstructure elements  12  may be disposed and the conductors  26  may be formed by disposing silver, copper, aluminum or other suitable conductive metals between the sides  32  and the dielectric binder  14 . The conductors  16 ,  18  or  26  may have electrical conduits  21  connected at a surface or electrically connected through the dielectric substrate  15 .  
         [0025]     Other variations are possible as illustrated in  FIG. 5  wherein a base conductor  16  may be formed by deposition in a dielectric substrate  15  material and the top conductor  18  may be formed as previously disclosed. The dielectric substrate  15  material in each case may be flexible to rigid and be fiberglass, silicone and other suitable non-conductive material. In the instance of the use of a base conductor  16  in a dielectric substrate  15 , the base conductor  16  may penetrate to the bottom surface of the dielectric substrate  15  or be contained within the dielectric substrate  15 .  
         [0026]     Referring to  FIGS. 6 through 8 , the microstructure visible light source  10  units may be fabricated in array structures by for example forming channels  30  in a dielectric or metal substrate  15  and disposing the microstructure visible light source  10  units in the channels  30 . The geometry of an array may be used to control impedance matching.  
         [0027]     The channels  30  may have a dimension of approximately 20 microns that may be the diameter of a spherical microstructure element  12  or dimensions of approximately 2 to 200 mils. The vertical and horizontal dimensions may be different. The shape of a channel may be arbitrary; rectangular is for illustrative purposes only. The channels  30  may also be formed in any desired pattern. The dielectric substrate  15  may be formed with metallic material having dielectric regions for microstructure visible light sources  10  and having positive and neutral electrical conduits for each array channel  30 .  
         [0028]     Arrays of microstructure visible light sources  10  may be formed in a pattern that may allow electronic addressing of individual portions of the array by the control of base conductors. This may allow specific areas of an array to be turned on and off or changed in intensity to produce a desired effect. The portions that may be controlled may be of arbitrary size, number and shape. The resolution may be as small as the size of a single microstructure. Such arrays may be constructed for control by a computer as the output display device or similar to plasma television displays.  
         [0029]     For example, individual areas or pixels of the microstructures may be formed to emit the red, blue or green portion of the spectrum. The pixels may be of arbitrary dimension, shape and number. The generation of color may be accomplished by using different gases or combinations of gases in the microstructure elements, by control of the size or shape of the microstructure elements and by control of the electrical field characteristics that may be exciting the microstructure elements. Materials such as Phosphorous may be coated on the individual microstructures or integrated into the dielectric substrate to create desired color effects. The colors may not need to be pure red, blue and green, but may be designed to optimize fabrication costs, efficiencies or image reproduction capability.  
         [0030]     Configurations of microstructure visible light sources may be used for replacement of fluorescent, filament, Halogen and the like light bulbs. Lighting structures may be fabricated that may be very thin, reference  FIG. 9 , for example, as wallpaper or as thick as desired. The lighting structure may be applied to walls, ceilings, floors, on land vehicles, into display units such as lamps, furniture and artwork. Displays such as billboards, signs and the like may also include visual light structures. The small size and other characteristics of the microstructure visible light source may also be useful in chemical detection, UV light generation, photodynamic therapy, gas chromatography and other emitted light applications. Microstructure visible light sources may be formed that may be rigid or flexible and of arbitrary shape and thickness.  
         [0031]     While the invention has been particularly shown and described with respect to the illustrated embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.