ENCLOSURES WITH LIGHT EMITTING DIODES WITHIN

Abstract

A light emitting assembly comprising a solid state device, when and if coupleable with a power supply constructed and arranged to power the solid state device to emit from the solid state device a first wavelength radiation, and an enveloping vessel enhancing the luminescence of the solid-state device and providing a mechanism for arranging luminophoric medium in receiving relationship to said first, radiation, and which in exposure to said first radiation, is excited to responsively emit second wavelength radiation or to otherwise transfer its energy without radiation to a third radiative component. In a specific embodiment, monochromatic blue or UV light output from a light-emitting diode is converted to achromatic light without hue by packaging the diode with fluorescent organic and/or inorganic fluorescers and phosphors on the walls of the solid-state light envelope which keeps the diode and the fluorescers and phosphors under a vacuum or a rare or Noble or inert gas.

Claims

1. A microelectronic device, comprising: a plurality of light-transmissive enclosures, at least one fully within another; at least one outer light-transmissive enclosure, said enclosure removably coupled to a metal base, both forming jointly when coupled the outer boundary of the device which defines an inner space; at least one light-emitting diode array with a plurality of light-emitting diodes each including at least one p-n junction operable to emit primary radiation when energized with an electrical connection, positioned fully within at least one secondary light-transmissive enclosure that isolates the light-emitting diode die from a polymeric or other encapsulating matrix that forms part of an outer boundary of the secondary light-transmissive enclosure, and which defines a secondary interior space; a gas within the inner space; and a thermal connection within said inner space with at least one light-emitting diode die, a gas, at least one metal base; wherein heat is dissipated to the external surroundings through the inner space by radiation and through the base by conduction.

2. The device of claim 1, wherein the interior space has a region under vacuum.

3. The device of claim 1, wherein the interior space has a gaseous region.

4. A solid-state light-emitting device, comprising: at least one single-die semiconductor light-emitting diode assembly with a p-n junction operable to emit light when energized with an electrical connection: at least one light-transmissive enclosure, said enclosure removably connected to a base, both forming, when connected, the outer boundary of the device which defines an inner space; at least one vent, disrupting the continuity of the connection between the paired optically-transmissive enclosure and metal base; and at least one light-emitting diode die fully within a second enclosure; wherein the interior volume of the second enclosure is a clear or translucent polymer, wherein heat is dissipated to the external air surroundings through the base by conduction; wherein heat is dissipated to the external air surroundings through at least one light-transmissive enclosure by radiation; wherein heat is dissipated to the external air surroundings through at least one vent by convection.

5. The device of claim 1, wherein the inner space contains a gas other than oxygen.

6. The device of claim 5, wherein the gas is air, nitrogen, argon, krypton or xenon or any combination thereof.

7. The device of claim 1, wherein a fluorescent, a phosphorescent, a thermo-luminescent or an electro-luminescent material is a thin layer on the inner wall of the outer light-transmissive enclosure.

8. The device of claim 4, further comprising a fluorescent, a phosphorescent, a thermo-luminescent or an electro-luminescent material.

9. The device of claim 7, wherein a single-die semiconductor light-emitting diode emits a primary radiation and contains at least one luminescent element that is radiatively excited by primary radiation to cause the luminescent element to emit secondary radiation wherein the luminescent element is exposed to a gas.

10. The device of claim 9, wherein at least one luminescent element emits achromatic or chromatic light and wherein the outer light-transmissive enclosure acts as a filter of less than all primary radiation.

11. The device of claim 4, further comprising a luminescent element; wherein heat from the location of the Stokes shift is dissipated to the external surroundings through the base by conduction; wherein heat from the location of the Stokes shift is dissipated to the external surroundings through at least one light-transmissive enclosure by radiation; wherein heat from the location of the Stokes shift is dissipated to the external surroundings through at least one vent by radiation; and wherein heat from the location of the Stokes shift is dissipated to the external surroundings through at least one vent by convection.

12. The device of claim 1, further comprising: at least one single-die semiconductor light-emitting diode (LED), comprising a GaN, InGaN, AIGaN, semiconductor, or a semiconductor comprising Ga, N, In or Al configured to emit a primary radiation which is the same for the at least one single light-emitting diode die in at least one light-emitting diode array present in the device, said primary radiation being a relatively shorter wavelength radiation; and a collection or concentration luminophoric medium arranged in receiving relationship to said primary radiation, wherein the luminophoric medium responsively emits a secondary, relatively longer wavelength, polychromatic radiation when the luminophoric medium is excited via exposure to the primary radiation, wherein separate wavelengths of said polychromatic radiation mix to produce an achromatic or a chromatic light output.

13. The device of claim 12, further comprising an outer most light-transmissive enclosure including glass or a plastic.

14. The device of claim 8, wherein a fluorescent, a phosphorescent, a thermo-luminescent or an electro-luminescent material is a thin layer on the inner wall of the outer light-transmissive enclosure.

15. The device of claim 8, wherein a fluorescent, a phosphorescent, a thermo-luminescent or an electro-luminescent material is within the interior volume of the second enclosure.

16. The device of claim 8, further comprising a fluorescent, a phosphorescent, a thermo-luminescent or an electro-luminescent material as a thin layer on the light-emitting diode die.

17. The device of claim 8, further comprising a luminescent material with a radiative lifetime of less than seventy-five nanoseconds.

18. The device of claim 8, further comprising a luminescent material with a radiative lifetime of more than fifty nanoseconds and less than one-hundred nanoseconds.

19. The device of claim 7, further comprising a luminescent material with a radiative lifetime of less than 75 seconds and more than one nanosecond.

20. The device of claim 1, further comprising a vent on the outer boundary of the device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0189] FIG. 1 shows an embodiment of a light emitting diode assembly constructed in accordance with the present disclosure and incudes a side view.

[0190] FIG. 2 shows an embodiment of a light emitting diode assembly constructed in accordance with the present disclosure.

[0191] FIG. 3 shows an embodiment of a light emitting diode die within an enclosure and a plurality of embodiments of a lighting element comprising a light emitting diode.

[0192] FIG. 4 shows a plurality of embodiments of a lighting element comprising a light emitting diode and a down converting element.

[0193] FIG. 5 shows an embodiment of an orthogonal view (otherwise hidden in operation) with a plurality of embodiments of a lighting element comprising a plurality of light-emitting diode 1 by x arrays mounted onto a metal base which forms the outer boundary of a light-emitting lighting fixture.

[0194] FIG. 6 shows an embodiment of an orthogonal view of an embodiment of a light-emitting fixture comprising an outer light-transmissive boundary of a light-emitting fixture.

[0195] FIG. 7 shows an embodiment of a perspective view of an embodiment of a light-emitting fixture comprising an outer optically-transmissive enclosure and a metal base from which the former is secured.

[0196] FIG. 8 shows an embodiment of a light emitting diode array constructed in accordance with the present disclosure.

SUMMARY OF THE INVENTION

[0197] The present invention is based on the discovery that a highly efficient achromatic, chromatic and non-visible light emitting device may be simply and economically fabricated utilizing solid state light emitting diode dies that in the absence of certain elements of the following generates primary radiation which transfers its energy, radiatively, to secondary luminescent elements where the diode die and or the secondary luminescent elements are in an enhancing and or protecting enclosure.

[0198] The present invention relates broadly to a semiconductor light emitting assembly comprising a solid-state device with at least one p-n junction which induces the emission from the solid-state device of a first wavelength radiation to chromatic radiation (radiation, light, luminance or illuminance with hue), or achromatic radiation (radiation, light, luminance or illuminance) without hue. The solid state device is structurally associated with a recipient down-converting luminophoric medium, as hereinafter defined, which when either radiatively or otherwise impinged by the first relatively shorter wavelength radiation, or is otherwise non-radiatively excited, through Forster or Dexter energy transfer from the excited states that absent the energy transfer would radiatively emit a first relatively shorter wavelength radiation, or the secondary luminescent elements as hereinafter defined within the luminophoric medium are otherwise non-radiatively excited, through Forster or Dexter energy transfer from the excited states that absent the energy transfer would radiatively emit a relatively shorter wavelength radiation, to responsively emit a secondary radiation, chromatic and achromatic, polarized or unpolarized, in the visible and non-visible light spectrum. The recipient down-converting luminophoric medium is protected by virtue of a segregating envelope from elements that instantaneously decrease performance or over long term reduce effectiveness of the down-converting medium. When the segregating envelope is constructed to also include the active layer of the solid-state device, the same envelope introduces and maintains a favorable environment to maintain, sustain, protect or increase performance of the underlying semiconductor with a p-n junction where said performance is the ability to generate light and or to transfer its energy non-radiatively.

[0199] In accordance with a specific embodiment of the present invention, an LED operative to emit, for example, monochromatic blue or ultraviolet (UV) radiation is packaged along with fluorescent organic and/or inorganic fluorescers and phosphors—the secondary luminescent elements in the luminophoric medium—in an insulating or isolating chamber (an assembly), such as a sealed glass ampoule, said package molded within and suspended within a matrix otherwise protecting the aforementioned assembly. In the case of radiative energy transfer, the monochromatic blue or UV radiation output of the LED is absorbed and then down converted by the fluorophor or phosphor—the secondary luminescent elements in the luminophoric medium—to yield longer wavelengths to include a broad spectrum of frequencies which appear to an observer as white light. The atmosphere or in the case of a vacuum, the absence of atmosphere, within the insulating or isolating chamber is selected to increase the probability that the luminophors (the secondary luminescent elements in the luminophoric medium) required to effect down conversion of light from an LED responsively emit light of secondary radiation.

[0200] This use of an insulating or isolating chamber to enhance the secondary radiative probability of the fluorescers and/or phosphors to effect down conversion of light from an LED in a solid-state light emitting device using a dye or pigment material (a luminophor that fluoresces or phosphoresces; the secondary luminescent elements in the luminophoric medium) is a significant departure from prior art teaching. In addition to allowing for the generation of achromatic (white) light from a blue or ultraviolet emitting LED die with a typical p-n junction construction without destruction of the luminophors so selected, devices in accordance with the invention can be variously constructed to provide an essentially infinite series of colored (visible) light emissions, of either narrow or broad spectral distribution, from one single p-n junction construction.

[0201] As used herein, the term “solid state device,” used in reference to the device for generating the primary radiation which subsequently is down-converted to a longer wavelength radiation in such visible achromatic (white) or chromatic (color) light spectrum, means a device which is selected from the group consisting of semiconductor light emitting diodes, semiconductor lasers, thin film electroluminescent cells, electroluminescent display panels, and internal junction organic electroluminescent devices.

[0202] As used herein, the term “primary radiation” means the initial photons directly produced by hole-electron recombination at a p-n junction.

[0203] The term “secondary radiation” means the photons subsequently generated by virtue of transfer of the energy of the excited state that defines the p-n junction to form some other excited state and the radiation that is released by virtue of relaxation of this other excited state.

[0204] As used herein, the term “luminophoric medium” refers to a material which in response to radiation emitted by the solid-state device or is otherwise non-radiatively excited, emits light—achromatic light or color light in the visible light spectrum—by fluorescence and/or phosphorescence or emits infra-red light in the non-visible light spectrum. The term “down-converting medium” is synonymous in our usage with “luminophoric medium” as the luminophors of interest and discussion herein are those that have a Stokes shift.

[0205] As used herein, the term “secondary luminescent elements” refers to the specific materials that together—whether intimately mixed or not, whether spatially separated or not—comprise the luminophoric medium.

[0206] As used herein, the term “chamber” refers to a natural or artificial enclosed space or cavity whose atmosphere can be controlled during assembly or during use. The term “envelope” is used interchangeably with the term “chamber.” In certain discussions, the term “secondary enclosure” is used and is by virtue of my assertion tantamount with how the term “chamber” and “envelope” is utilized. The term optically transmissive enclosure is often used in the instant invention to describe the matter, an assembly of material parts, that forms the external boundary of the natural or artificial enclosed space or cavity whose atmosphere can be controlled, and the volume so enclosed is referred to as either an inner space or an interior space, as contextually clear from how it is used. In other words, in the specification and claims of the instant invention, the term enclosure is used to described that which encloses as opposed to or in addition to that which is enclosed. When used in the context of that which encloses, an optically transmissive enclosure is one that allows for the transport of radiation (light) from the space that is enclosed through the boundaries that make up the enclosure to the outer world. The term optically transmissive enclosure allows for a portion of the boundaries (which define the enclosure) to allow light to be transported through, e.g., not all of the boundaries may be transmissive or transparent. That portion of the enclosure boundaries that are transmissive may be those which direct or transport light to the external surfaces in the external environment and that provides the desired amount of illuminance onto that surface. In at least some exemplary embodiments, when the boundaries of the enclosure contain matter that is not optically transmissive it is usually because the external surface facing the opaque boundary is one where the adjacent space does not have any illuminance (e.g., a specific area on the surface of a ceiling or a wall to which the lighting fixture is flush mounted, said specific area being of similar size to the size of the opaque boundary of the outermost enclosure).

[0207] As used herein, the term “atmosphere” refers to a surrounding influence or environment.

[0208] As used herein, the term “white light” and “achromatic light” refers to visible radiation possessing no hue. Achromatic light is free of color; achromatic pigment or dye is a color perceived to have no hue, such as neutral grays. White light is light perceived as achromatic, that is, without hue.

[0209] As used herein, the term “colored light” and “chromatic light” refers to visible light having hue.

[0210] As used herein, the term “hue” refers to visible light with the attribute of colors that permit them to be classed as red, yellow, green, blue, or an intermediate between any contiguous pair of these colors.

[0211] As used herein, the term “tint” refers to a variation of a color produced by adding white to it and characterized by a low saturation with relatively high lightness.

[0212] As used herein, the term “shade” refers to the degree to which a color is decreasingly illuminated; that is, a gradation of darkness for color light.

[0213] As used herein, the term “removably coupled” means for example to move by lifting, pushing aside, or taking away or off (removably being an adjective of coupled) that to which it is otherwise paired or connected.

[0214] As used herein, the term p-n junction means for example an interface or a boundary between two semiconductor material types, namely the p-type and the n-type, inside a semiconductor. The p-side or the positive side of the semiconductor may have an excess of holes and the n-side or the negative side may have an excess of electrons.

[0215] As used herein, the term convection means for example the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat.

[0216] As used herein, the term fluid means for example a substance that has no fixed shape and yields easily to external pressure; a gas or (especially) a liquid.

[0217] As used herein, the term conduction means for example the process by which heat is directly transmitted through a substance when there is a difference of temperature between adjoining regions, without movement of the material.

[0218] As used herein, the term thermal radiation is for example a process by which energy, in the form of electromagnetic radiation, is emitted by a heated surface in all directions and travels directly to its point of absorption; thermal radiation may not involve an intervening medium to carry it.

[0219] As used herein, the term fluorescent means for example a radiative transition without a change in spin multiplicity from the excited state from which it emits to the lower energy state to which, after light emission, it remains.

[0220] As used herein, the term phosphorescent means for example a radiative transition with a change in spin multiplicity from the excited state from which it emits to the lower energy state to which, after light emission, it remains.

[0221] As used herein, the term electro-luminescent means for example a radiative transition with or without a change in spin multiplicity from the excited state, itself populated by an electrical current and from which it emits to the lower energy state to which, after light emission, it remains.

[0222] As used herein, the term thermo-luminescent means for example a radiative transition with or without a change in spin multiplicity from the excited state, itself populated by an applied heat and from which it emits to the lower energy state to which, after light emission, it remains.

[0223] As used herein, the term radiative lifetime means for example the lifetime of an electronic state in the situation where only radiative processes depopulate that level, or otherwise recognized as the reciprocal of the rate of luminescence.

[0224] As used herein, the terms optically transmissive and optically transmissive enclosures mean for example the same.

[0225] As used herein, boundary means for example a line that marks the limits of an area; more specifically outer boundary means the edge of the device or assembly (or fixture) that marks the limits of the area of said device with the external surroundings.

[0226] As used herein, a thermodynamic definition of outer boundary may be a closed surface surrounding a system through which energy and mass may enter or leave the system. Everything external to the system is for example the surroundings. In at least some exemplary embodiments of the instant invention, mass may enter, and mass may leave the luminaire through the vents (convection) and through the entry and exit ports.

[0227] As used herein, optically-transmissive means for example either the full or partial transport (through the surface) of thermal radiation or luminescence—including electroluminescence, scattered electroluminescence, and fluorescence—or both (thermal radiation and luminescence).

[0228] Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing description and claims. This application claims priority from Provisional Application Ser. No. 60/569,007 filed 7 May 2004.

Detailed Description of the Invention and Exemplary Embodiments Thereof

[0229] The present invention is based on the discovery that a highly efficient light emitting device may be simply and economically fabricated utilizing a solid state light emitting diode die that either generates primary radiation (acting as a radiative donor) or non-radiatively transfers energy (acting as a non-radiative donor) from the excited state-which defines the p-n junction under an applied voltage—and where the diode die (the donor) and or the acceptor of primary radiation and or non-radiative energy transfer is in an enhancing and or protecting enclosure.

[0230] Less broadly, the present invention is based on the discovery that a highly efficient achromatic, chromatic and non-visible light emitting device may be simply and economically fabricated utilizing a solid state light emitting diode die (a donor) approximate to a luminophoric medium (an acceptor) that in the absence of certain elements of the following generates primary radiation and where the excited state—which defines the p-n junction under an applied voltage—transfers its energy, radiatively or non-radiatively, to secondary luminescent elements in the luminophoric medium and where the diode die and or the luminophoric medium are in an enhancing and or protecting enclosure.

[0231] Less broadly, the present invention is based on the discovery that a highly efficient achromatic, chromatic and non-visible light emitting device may be simply and economically fabricated utilizing a solid state light emitting diode die proximate to a luminophoric medium that in the absence of certain elements of the following generates primary radiation and where the excited state—which defines the p-n junction under an applied voltage—transfers its energy, radiatively or non-radiatively, to secondary luminescent elements in the luminophoric medium and where the diode die and the luminophoric medium are both in the same enhancing and or protecting enclosure.

[0232] When the diode die is placed with a protecting and enhancing chamber or envelope, the diode die is separated from the resin that absent this invention completely covers the diode die; further in this embodiment, the protecting and enhancing envelope contains within its internal boundaries' material of a gaseous, liquid or solid phase that protects and enhances the generation of primary light or non-radiative energy transfer from the light emitting diode die. When the luminophoric medium is placed with a protecting and enhancing chamber or envelope, the luminophoric medium is separated from the resin that absent this invention completely covers the diode die; further in this embodiment, the protecting and enhancing envelope contains within its internal boundaries' material of a gaseous, liquid or solid phase that protects and enhances the generation of secondary radiation from the luminophoric medium itself.

[0233] Achromatic light LED solid state devices may be made by the method of the present invention. It is preferred in at least some exemplary embodiments that achromatic light if made is affected is through down-conversion, although there is no requirement that the invention be limited to generating achromatic light nor is the invention limited to achromatic light through down conversion. If achromatic light is generated utilizing a down conversion process whereby an excited state that either generates a primary photon—or otherwise is capable of generating a primary photon absent energy transfer—generated in the active region of the diode, then said primary radiation is down converted with primary blue emission and/or secondary blue fluorescent or phosphorescent centers, as well as green and red fluorescent or phosphorescent centers where the fluorescent or phosphorescent centers are within a chamber and are protected by a vacuum or a beneficial atmosphere or by some other enhancing effect within or impacting the chamber. These fluorescent and or phosphorescent centers comprise the luminophoric medium. Such an LED device is able to down-convert the relatively monochromatic light, typical of all heretofore monochromatic LED dies and lamps, to a broader emission that appears as achromatic light from red, green, and blue emission centers. Such a device is also able to enhance the efficiency of generation of primary radiation in the absence of luminophors as the beneficial atmosphere augments the generation of primary light by virtue of access of the beneficial atmosphere to the active layer the defines the semiconductor p-n junction. As one skilled in the art will immediately observe, the primary photon generated in the active region of the diode may be a blue photon or an ultraviolet photon, if only one diode die is utilized. There is no requirement that only one diode die be utilized.

[0234] Under certain circumstances, it may be desirable for both the light emitting diode die and the luminophoric medium to be enclosed in the same chamber, in separate chambers, or only one of the two in a chamber.

[0235] When the luminophoric medium contains luminescent elements that emit red, green and blue light, in the case of a uv LED die, or 1) red, green and blue light; 2) yellow; 3) red, green and yellow, or other suitable combination of primary and complementary colors in the case of a blue LED die, achromatic light is generated.

[0236] When two LED die of different wavelengths are used, for example and uv and a blue LED die, then the luminophoric medium can be optimized to generate achromatic light by adjusting in concentration or in space the secondary luminescent elements. It is preferred in at least some exemplary embodiments that the two LED die be of different wavelengths with as large a gap between their respective emission wavelength maximum as possible. When a blue LED die and a cyan LED die are used, then the luminophoric medium will contain secondary luminescent elements that emit in the yellow and in the red. When a uv and green LED die is utilized, then the secondary luminescent elements will be blue and red; when a blue and red LED die are utilized, then the secondary luminescent elements will be green. When a blue LED die and a yellow or amber LED die are utilized, then the secondary luminescent elements need only be adjusted to optimize the color temperature of the achromatic light. The invention is not limited to secondary luminescent elements of multiple molecular compositions (for example, a red emitter, a green emitter, and a blue emitter) as single component emitters are known that generate achromatic light when suitably activated. In at least some exemplary embodiments, a preferred white-emitting phosphor comprises zinc sulfide activated with copper, manganese, chlorine, and, optionally, one or more metals selected from gold and antimony. In at least some exemplary embodiments, a preferred phosphor is Mn doped ZnS nano clusters with no less than 5% and no more than 9% Mn, prepared from a colloidal route and where ultraviolet-visible absorption curves show that on changing the concentration of Mn2+ ions, there is a maximum in the band gap for an optimum doping (5.5% of Mn), and where the fluorescence spectra of the doped clusters consist of two distinct emissions: orange and blue.

[0237] It is immediately apparent to a skilled practitioner of the teachings presented herein that achromatic light may be formed by methods other than down conversion and this invention is not limited to the implementation of down-conversion for the generation of achromatic light.

[0238] When two light emitting diode dies are utilized at least one must be internal to the chamber and where the secondary luminescent elements are, if utilized, internal of external to the chamber, are dependent of optimization of the output and durability of the lamp so constructed. When at least one chamber contains only luminescent elements and not a semiconductor die, that chamber just described is replaceable and interchangeable at will.

[0239] When both the diode die and dice are in a chamber and the secondary luminescent elements are in a chamber, they need not be in the same chamber for radiative energy transfer to take place; they only need to be in a geometric relationship such that the latter receives the primary radiation emanating from the diode die or dies.

[0240] A significant advantage of organic luminescent materials is their relatively broad emission bandwidth that offers the maximal overlap of photon wavelengths to generate an achromatic illumination most readily. Prior to this invention, when multiple luminophors were in use (red, green and blue luminophors) it had been most desirable to utilize fluorescent materials with extremely short radiative lifetimes, less than 50 nanoseconds, to preclude non-radiative energy transfer (to the lowest energy emitter). However, solid-state lighting requiring an after-glow, illumination provided after the power supply is shut off, is not otherwise available since after-glow devices require luminophors with a lifetime greater than 50 nanoseconds, in fact millisecond lifetimes are more specifically preferred in at least some exemplary embodiments. It is for the most part desirable that fluorescent materials or phosphorescent materials with a radiative lifetime greater than 50 nanoseconds be spatially separated within a chamber and by virtue thereof, these down-conversion luminophors can continue to provide achromatic or chromatic illumination after the power supply is shut off.

[0241] It is for the most part desirable that organic fluorescent materials and organic phosphorescent materials are incorporated within a chamber under vacuum or noble gas or other inert media so as to avoid the opportunity for oxidation of the luminophoric medium instantaneous to their excitation or otherwise degrade the luminophoric medium over an extended period of time. It is also desirable for inorganic or ceramic luminophors to be incorporated within a chamber under vacuum or noble gas or other inert gas or inert liquid or inert solid to avoid the opportunity for quenching with any quencher—a gas, liquid or solid not inert. It is recognized by one skilled in the art that the mechanism by which gases such as nitrogen, argon, krypton, and xenon are utilized in incandescent lamps is different than the mechanism in which it is utilized in this invention and that it has not heretofore been recognized, prior to this invention, that gases have a beneficial effect in the long-term totality of lighting from p-n junctions or in solid-state lighting devices. The primary utility of gas in incandescent lighting is related to regeneration of the filament first; the utility of the gas also relates to convection and conduction of heat and to prevent the vaporization of the underlying filament element and the inert gas contains a regenerative gas which returns material evaporated from the filament back to the filament. The primary utility of gas in the invention being claimed herein is the protection of the secondary luminescent elements within the luminophoric medium from the deleterious effects of oxygen and other quenchers. The utility of this invention is apparent when it is recognized that when gas is utilized in mercury vapor lamps, as opposed to incandescent lamps and or solid-state lamps with a p-n junction, the primary purpose for doing so is for conductive and or convective heat flow to activate the phosphors which perform better at a higher temperature: Johnson (1984) claims embodiments in which the phosphor employed exhibits a higher efficiency at elevated temperatures and the chamber space includes inert gas such as nitrogen or argon so that some convective and/or conductive heat flow may be provided to the phosphor to permit arc tube to provide the desired operating temperature for the phosphor.

[0242] Notwithstanding the primary benefit of the invention being claimed herein, it has heretofore not been recognized that the p-n junction—in a LED lamp—itself will benefit from operating in an environment such as claimed herein. The prior art shows no examples of LED die lamps, or solid-state lamps with a p-n junction, whereby the p-n junction used for general illumination lighting is purposely sequestered within a chamber and that the chamber contains gas to enhance the performance of primary radiation from the p-n junction itself. It is also desirable for the diode die to be incorporated within a chamber or otherwise exposed to a noble or inert gas (or inert liquid or inert solid) whereby the index of refraction of the inert media are more closely aligned with the index of refraction of the light emitting diode die. A skilled practitioner of the art of enhancing light emission in incandescence will note that the benefit of filament exposure to gas has not been correlated with the index of refraction of the gas itself although, in incandescent lamps, the index of refraction of solids and the beneficial design thereof, has been noted. (Warren, et. al., 1976, Westinghouse Electric Company; Tschetter et. al., 1985, General Electric Company)

[0243] Notwithstanding the invention itself, others have noted that the operational performance of LED diode die may benefit from dissipation of charge or dissipation of heat and the mechanism by which this has been achieved is through the use of a ceramic heat sink. (Lamina on Metal Ceramic Solutions, “Thermal performance is the key to achieving high luminous densities, high reliability and long life. Lamina's LTCC-M (low temperature co-fired ceramic) packaging allows LED devices (die) to be mounted directly to an engineered metal core without submounts. This creates the optimum thermal path to conduct heat away from the LED device. The result is that multiple devices can be located in close proximity while maintaining target LED junction temperatures.”, White LED Light Engine Product Specification Sheet, Lamina Ceramics, Inc., 120 Hancock Lane, Westampton, N.J. 08060.) However, the use of a gas to optimally manage heat, from one enclosure through another, for a solid-state lamp with a p-n junction has not heretofore been taught. Further, in the specific case where the ceramic submount of Lamina are preferred in at least some exemplary embodiments, the method of this invention allows for said submounts to be sequestered within the protecting and enhancing chamber. However in at least some exemplary embodiments, the instant invention is one that does not rely on a ceramic heat sink nor may it have an engineered metal core.

[0244] In the special case where both the diode die and the secondary luminescent element are sequestered within the same chamber, it is for the most part desirable that the chamber that sequesters within it the p-n junction also contain an inert gas or inert liquid or inert solid with excellent heat conduction if the p-n junction is more sensitive to heat than the luminophors so as to remove heat from the p-n junction itself. It is preferential in at least some exemplary embodiments that nitrogen or argon be used as krypton conducts heat less than argon does, and xenon conducts heat less than even krypton does. Note that this embodiment is the opposite of that which is required with incandescence of tungsten filament in a sealed light bulb. It is generally the case that when inorganic luminophors are utilized, the heat insensitivity of these inorganic luminophors is such that it is preferred in at least some exemplary embodiments to dissipate the heat away from the p-n junction. In the case where the light output of the inorganic luminophor requires a high temperature in at least some exemplary embodiments, then it is preferred to use nitrogen or argon or other gas with excellent heat conductivity.

[0245] It is for the most part desirable that the chamber that sequesters within it the p-n junction also contains an inert gas or inert liquid or inert solid with poor heat conduction if the p-n junction is less sensitive to heat than the luminophors so as to preclude heating the luminophors themselves. It is preferential in at least some exemplary embodiments that xenon be used as krypton conducts heat less than argon does, and xenon conducts heat less than even krypton does. It is generally the case that when organic luminophors are utilized in at least some exemplary embodiments, the high heat sensitivity of these organic luminophors is such that it is preferred to not dissipate the heat away from the p-n junction.

[0246] Environmental effects, such as available with this invention, on luminescence efficiency—even when quenching or its absence is not a factor—is well known. Effects such as spin-orbit coupling—which enhance moving between states of different multiplicities and therefore enhance the efficiency of luminescence when multiplicity changes (i.e., phosphorescence)—can be effected by the environment that the excited state species finds itself in. Sequestering the luminophoric medium that contains a phosphorescent luminescent element within a chamber as described herein allows for enhancement of the underlying luminescence efficiency by introducing a molecule within the chamber that interacts with the luminophors therein and which the molecule has a heavy atom effect. The heavy atom effect is well known and is the enhancement of the rate of a spin-forbidden process by the presence of an atom (for example bromine) of high atomic number, which is either part of, or external to, the excited molecular entity. Mechanistically, it responds to a spin-orbit coupling enhancement produced by a heavy atom. (IUPAC Compendium of Chemical Terminology 2nd Edition (1997), 1996, 68, 2245)

[0247] Chromatic light LED solid state devices may be made by the method of the present invention. While not necessary to produce chromatic light, it is apparent that the devices of this invention may produce chromatic light, utilizing a down conversion process whereby an excited state that either generates a primary photon or otherwise is capable of generating a primary photon absent non-radiative energy transfer generated in the active region of the diode is down converted with primary blue or primary uv or primary blue and uv emission and/or secondary blue fluorescent or phosphorescent centers, as well as green or red fluorescent or phosphorescent centers where the fluorescent or phosphorescent centers are within a chamber and are protected by a vacuum or a beneficial atmosphere or by some other enhancing effect within or impacting the chamber. Such an LED device is able to down-convert the relatively monochromatic light; typical of all heretofore colored LED dies and lamps, to a broader emission that provides chromatic light from red, green, and blue emission centers. The secondary luminescent elements may be selected and varied as desired, with control of concentrations and spatial arrangements of each selected secondary luminescent element such that the light generated by the luminophoric medium provides color of any hue and apparent tint. Chromatic light with a strong tint is in fact pale color light, for general illumination. Chromatic light with a strong shade is not useful for general illumination but is beneficial for clandestine applications of lighting and signaling. Such a device for chromatic light emission, based on down-conversion, requires a LED solid state device to generate primary light that is either blue or ultraviolet in emission, or can generate primary light that is either blue or ultraviolet in emission absent non-radiative energy transfer, such as is available using blue or ultraviolet LED dies and lamps. It is an important element of this consideration that either inorganic or organic fluorescent or phosphorescent materials can be utilized to down-convert the primary ultraviolet or blue light emission to a mixture of blue, green and red luminescent emissions. A significant advantage of organic luminescent materials is their relatively broad emission bandwidth which offers the maximal overlap of photon wavelengths to generate a chromatic illumination most readily. Further, it is most desirable to utilize organic fluorescent material with extremely short radiative lifetimes, less than 50 nanoseconds, to preclude non-radiative energy transfer (to the lowest energy emitter) since an after-glow is not desired in this embodiment. It is for the most part desirable that organic fluorescent materials and organic phosphorescent materials are incorporated within a chamber under vacuum or noble gas or other inert media so as to avoid the opportunity for oxidation of the luminophoric medium instantaneous to their excitation or over an extended period of time.

[0248] A significant part of certain inorganic phosphors is that they can absorb more than one photon prior to radiatively relax to their ground state. This is preferred in the exemplary case of solid-state lighting of the design described herein for this invention and where it is observed a saturation of the primary photon absorption. In this exemplary case, it is preferred to maximally down-convert the primary photons, even though the observed saturation occurs with most ceramic phosphors utilized heretofore. It is preferred in at least some exemplary embodiments then to use a ceramic phosphor that can absorb more than one photon and it is preferred that this occurs with luminophors of extremely long lifetime. An excellent ceramic phosphor with extremely long lifetime is SrAl2O4 phosphors doped with Eu and Dy. In an exemplary embodiment, the phosphor so identified in the immediately preceding sentence is coated on the interior walls of the chamber, using dispersion in a binder, and after the film is dried, the layer of selected phosphor is capable of absorbing multiple photons while immobilized within the desired chamber. The phosphors may also be coated on the sapphire substrate in which a GaN on sapphire LED is constructed. The phosphors may also be added to a previously evacuated chamber within in which a LED die has already been assembled and where dispersion of the material is enhanced by the vacuum itself.

[0249] As discussed above, there have been disclosures regarding the generation of white light in solid state semiconductor devices with p-n junctions using radiative energy transfer and these examples use primarily inorganic dopants near the active layers of the p-n junctions or organic fluorescers within the epoxy matrix encapsulating the semiconductor, but none are known that apply the principles of the present invention to semiconductor-based p-n junction LED lamps. It has not been heretofore recognized than organic luminophors can acts as dopants and non-radiative energy transfer will populate the excited states of these luminophors when so arranged to generate secondary radiation. Absent the invention described herein, the utilization of an isolating and protecting chamber, said non-radiative energy transfer is not effective. As an example, benzophenone is frequently used as a triplet sensitizer using the mechanism of Dexter energy transfer previously described. Benzophenone when excited enters a singlet excited state and then rather rapidly crosses over into its triplet excited state through a process known to those skilled in the art as intersystem crossing. Once benzophenone triplet is formed—an excited state species that is easily quenched by the ground state of oxygen, itself a triplet, rendering the process sough after basically useless—it can transfer its energy non-radiatively to the ground state (typically a singlet) of a luminophor such as bis(phenyl-ethynyl) anthracene to form the excited triplet state of bis(phenyl-ethynyl) anthracene which is then able to phosphoresce. There is no other means of practically garnering the excited triplet state of bis(phenyl-ethynyl) anthracene other than through non-radiative energy transfer since radiative energy transfer only populates the singlet excited state and the efficiency of intersystem crossing from the singlet excited state to the triplet excited state in bis(phenyl-ethynyl) anthracene is essentially zero. However, as mentioned, triplet benzophenone is easily quenched by oxygen and triplet benzophenone is excellent at destroying through hydrogen abstraction the epoxy resin used normally in potting a LED lamp. Therefore, the invention herein described which includes among its elements a protecting and enhancing chamber, allows for immobilization of benzophenone within the isolating and protecting chamber, isolation and protection of benzophenone triplets so formed from quenching by either oxygen or hydrocarbons such as epoxy resin, and non-radiative energy transfer from the protected benzophenone triplet to a luminophor with the emission requirements required to form chromatic, achromatic or non-visible light emission.

[0250] Referring now to the drawings, FIG. 1 shows an achromatic or chromatic or infra-red light emitting diode assembly 10 constructed in accordance with the invention. This assembly comprises an enclosing wall 7 defining a light-transmissive enclosure 11 having an interior volume there within. The enclosure 11 may be formed of any suitable material having a light-transmissive character, such as a clear or translucent polymer, or a glass material. A second light-transmissive enclosure 111—which is the chamber or envelope of this invention—houses in its interior volume a light emitting diode (LED) die 13 positioned on support 14. First and second electrical conductors 16 and 17 are connected to the emitting and the rear faces 18 and 19 of LED die 13, respectively, and with the emitting face 18 of the LED die coupled to the first electrical conductor 16 by lead 12. The second enclosure 111 contains at least one light emitting diode die and reflective supports and is filled with a suitable down converting material 20, e.g., a down-converting medium or luminophoric medium comprising fluorescent and or phosphorescent elements (component(s), or mixtures thereof)—for example a luminophoric medium coated on the interior wall 112 of the secondary enclosure 111, which functions to down convert the light output from face 18 of LED 13 or reflecting off of surface 12 on which LED 13 rests to achromatic or chromatic or infra-red light. The down-converting medium need not be coated on the interior wall 112 of the secondary enclosure 111 but need only be within the outer wall of the secondary enclosure 111. The down-converting medium may be dispersed inside the second enclosure and not be attached, physically nor chemically to the interior wall. The second light-transmissive enclosure 111 is under vacuum or is filled with a medium that enhances, instantaneously or over the long term, primary radiation generated by the light emitting diode (LED) die 13 and or enhances, instantaneously or over the long term, the quantity and quality of secondary radiation generated by the luminophoric medium, and or enhances, instantaneously or over the long term the radiative or nonradiative energy transfer from the excited state in the active layer of the LED die 13 to the luminophoric medium. The active layer of the light emitting diode die is permanently within the space formed by the secondary enclosure and the reflecting posts onto which the light emitting diode die rests is also contained in the interior volume of the secondary enclosure. Note that luminophor may be coated on the external wall 113 of the secondary enclosure 111; in that case, however, the luminophor does not enjoy any additional benefit from the protecting and enhancing material enclosed within the secondary enclosure and is, in fact, in intimate contact with resin media 21. The material sequestered within the second enclosure 111 protects and enhances the emission of primary light as well as secondary light in contrast to gas sequestered within incandescent lamps which primarily regenerate the incandescent filament.

[0251] In one embodiment, the second enclosure 111 is filled with a gaseous medium that is inert such as argon gas and otherwise limits the oxidation or other means of bimolecular and unimolecular degradation of the luminophoric medium which contains fluorescent centers. Solely for the purpose of manufacturing, a dense inert gas such as argon is preferred in at least some exemplary embodiments so that when sealing the second enclosure, air is kept out of the enclosure and argon is kept inside of the enclosure. However, techniques for sealing chambers of the type presented herein, with inert gases and electrical leads permeating through an enclosure, such as a glass enclosure is well known and practiced.

[0252] In one embodiment, the second enclosure 111 is filled with a gaseous medium that is inert such as argon gas and otherwise prevents the quenching of the excited state of a phosphorescent component of the luminescent medium that provides secondary radiation after excitation by either primary radiation or non-radiative energy transfer.

[0253] In another embodiment, the second enclosure 111 is filled with a gaseous, liquid or solid medium and whereby the medium, whether completely inert or not, is selected solely for the basis of its index of refraction so that the selected medium has an index of refraction that maximizes the projection of primary radiation and or secondary radiation. Without any intention of limited the full range of materials that can be utilized to practice my invention, we claim the use of the following environment as operable environments when consideration of index of refraction is the most important consideration: in the series of vacuum, helium, argon, krypton, xenon, benzene, epoxy, carbon disulfide, sapphire, flint glass with 81% lead, cubic zirconia, GaN, and crystal iodine the index of refraction changes from 1.00, 1.00, 1.00, 1.29 (liquid), 1.38 (liquid), 1.501, 1.545, 1.63, 1.76, 1.805, 2.173, 2.45, and 3.340. The index of refraction roughly correlates with the density of the material, for organic molecules, the greater the high halogen content, the greater the density and the greater the index of refraction. Hence, methylene iodide has roughly the same index of refraction as sapphire (1.74 for the former vs. 1.77 for the latter), whereas 1-iodo-benzene and iodo-napthalene have refractive indices of 1.62 and 1.704, respectively. Solid medium of utility are zinc oxide (index of refraction of 2.02) antimony oxide (index of refraction of 2.09 to 2.29) zinc sulfide (index of refraction of 2.37), zirconium oxide (index of refraction of 2.40), rutile titanium oxide (index of refraction of 2.70). Many materials that can have high index of refraction have heavy atoms that also enhance spin-orbit coupling. Many organic polymers that are opaque to x-rays and do not degrade as a result of x-ray irradiation have heavy elements and as a result are inert solids in the context of this invention; moreover, these inert solids with heavy elements have a high index of refraction.

[0254] In another embodiment, the second enclosure 111 is filled with a gaseous, liquid or solid medium and whereby the medium, whether completely inert or not, is selected solely for the basis of its dispersion so that the selected medium has a low degree of dispersion of blue, green and red photons so that the achromatic light so formed does not appear to be subsequently dispersed back into their relative components.

[0255] In one embodiment, the secondary enclosure is filled with a liquid solvent that solubilizes the down-converting medium. In another embodiment, the secondary enclosure is filled with a polymeric resin other than an epoxy resin that normally pots a light emitting diode die and within which the down-converting medium is dispersed, solubilized, or otherwise suspended.

[0256] In one embodiment, the second enclosure is filled with a solid inactive matrix, such as a zeolite or a cyclodextrin that sequesters individual molecules of fluorescent components and otherwise limits bimolecular degradation of the fluorescent components. The secondary luminescent element is physically or chemically adsorbed to the zeolite cavity or is otherwise sequestered with a cyclodextrin cavity adopting the methodology of sequestering organic dyes in nano-porous zeolite crystals. (Irene L. Li, Z. K. Tang, X. D. Xiao, C. L. Yang, and W. K. Ge, Applied Physics Letters Vol 83(12) pp. 2438-2440. Sep. 22, 2003) Organic: ceramic hybrids may be used within the enclosure. In one embodiment, the organic luminophor such as a Lumogen derived diimide organic fluorescer is physically immobilized or covalently attached to a otherwise non-luminescent garnet aluminate structure such as an undoped yttrium aluminum garnet or to a doped yttrium aluminum garnet. In another embodiment, the organic fluorescer is immobilized within a xerogel with pores of less than 100 Angstroms. (Design of hybrid organic-inorganic materials synthesized via sol-gel chemistry by C. Sanchez and F. Ribot, New J. Chem., 18, 1007-1047 (1994); Hybrid organic-inorganic materials: The sol-gel approach by J. D. Mackenzie, in Hybrid Organic-Inorganic Composites, pp. 226-236 (1995)) In another embodiment, the dye Rhodamine is immobilized within a silica-zirconia material.

[0257] In another embodiment, organic fluorescent dye in the higher index of refraction material zirconia may be used. (E. Giorgetti, G. Margheri, S. Sottini, M. Casalboni, R. Senesi, M. Scarselli and R. Pizzoferrato, “Dye-doped Zirconia-based Ormosil planar waveguides: optical properties and surface morphology”, J. Non-Cryst. Solids, 255, 193 (1999). See also D. B. Mitzi, K. Chondroudis, and C. R. Kagan, “Organic-inorganic electronics”, IBM Journal of Research and Development, Volume 45, Number 1, 2001.)

[0258] In one embodiment, the secondary enclosure is glass ampoule produced on a standard ampoule filling and sealing machine.

[0259] In one embodiment, LED 13 comprises a leaded, gallium nitride-based LED which exhibits blue light emission with an emission maximum at approximately 450 nm with a FWHM of approximately 65 nm. Such a device is available commercially from Toyoda Gosei Co. Ltd. (Nishikasugai, Japan; see U.S. Pat. No. 5,369,289) or as Nichia Product No. NLPB520, NLPB300, etc. from Nichia Chemical Industries, Ltd. (ShinNihonkaikan Bldg. Mar. 7, 2018, Tokyo, 0108 Japan; see Japanese Patent Application 4321,280).

[0260] In one embodiment, the down-converting material on the interior of the second enclosure 111 comprises three luminophors, mixed together to form a uniform mixture: a blue fluorescer (Lumogen® F Violet 570—substituted napthalenetetracarboxylic diimide), a green-yellow fluorescer (Lumogen® F Yellow 083—substituted perylenetetracarboxylic diimide) and a red fluorescer (Lumogen® F Red 300—substituted perylenetetracarboxylic diimide). A composition comprising such blue, green-yellow, and red fluorescent materials, all organic based, as incorporated in chamber 111, is available commercially from BASF Pigment Division.

[0261] In one embodiment, the down-converting material is spatially separated on the interior of the second enclosure 111 and the separate three luminophors are: a blue fluorescer (Lumogen® F Violet 570—substituted napthalenetetracarboxylic diimide), a green-yellow fluorescer (Lumogen® F Yellow 083—substituted perylenetetracarboxylic diimide) and a red fluorescer (Lumogen® F Red 300—substituted perylenetetracarboxylic diimide). A composition comprising such blue, green-yellow, and red fluorescent materials, all organic based, as incorporated in chamber 111, is available commercially from BASF Pigment Division.

[0262] In one embodiment, the spatially separated materials are printed onto the interior wall using an ink-jet printer; the three luminophors are: a blue fluorescer (Lumogen® F Violet 570—substituted napthalenetetracarboxylic diimide), a green, yellow fluorescer (Lumogen® F Yellow 083—substituted perylenetetracarboxylic diimide) and a red fluorescer (Lumogen® F Red 300—substituted perylenetetracarboxylic diimide). A composition comprising such blue, green-yellow, and red fluorescent materials, all organic based, as incorporated in chamber 111, is available commercially from BASF Pigment Division.

[0263] One or ordinary skill will immediately acknowledge from the teachings presented herein that co-mingling multiple luminophors or physically separating them, by ink-jet printing of solutions of the luminophors and curing thereafter, is not limited to the Lumogen fluorescers presented herein in the preceding paragraphs but can be affected with organic luminophors and inorganic luminophors.

[0264] In one embodiment, the down-converting material on the interior of the second enclosure 111 comprises a blue fluorescer (Lumogen® F Violet 570—substituted napthalenetetracarboxylic diimide), a green, yellow fluorescer (Lumogen® F Yellow 083—substituted perylenetetracarboxylic diimide) and a red fluorescer (Lumogen® F Red 300—substituted perylenetetracarboxylic diimide). At the same time, on the exterior wall 113, of the second enclosure 111 is coated an inorganic phosphor such as Ce3+ doped yttrium aluminum garnet. A composition comprising such blue, green-yellow, and red fluorescent materials, all organic based, incorporated within chamber 111, is adjusted by virtue of adjusting the concentration of materials, to match the CIE coordinates of the inorganic Ce3+ doped yttrium aluminum garnet film on the outer wall of the second enclosure 111. In this manner, the operational performance of the solid-state device is prolonged by virtue of two identical luminescent elements of differing operations but identical photopic response.

[0265] In one embodiment, the ceramic phosphor written as Re3(Al1sGas)5O12:Ce:xMAl2O4 wherein Re is a rare earth selected from the group consisting of yttrium, gadolinium, and ytterbium; s is equal to or greater than 0 and less than or equal to 1; x is 0.01 to about 1.0%; and M is an alkali or alkaline earth metal is suspended as an emulsion with a polymerizable binder such as polyvinyl alcohol or polyvinylpyrrolidone-polyvinyl alcohol. A fixed amount of the phosphor binder material is applied to the inner wall of the chamber and the binder is then polymerized to form a robust phosphor thin film directly on the inner wall. Polymerization can be carried out using photo-initiation or thermally induced polymerization after which the chamber is used to assemble the LED lamp. Thus, the present invention includes using two-phase phosphors; a method of applying these two-phase phosphors to the chamber that coats the inner surface of the chamber and which said chamber is ultimately containing a vacuum or a gas selected from ammonia or other Lewis base, nitrogen, argon, xenon, and or krypton to make a LED lamp to produce achromatic light.

[0266] In one embodiment, the ceramic phosphor written as Re3(Al1sGas)5O12:Ce:xMAl2O4 wherein Re is a rare earth selected from the group consisting of yttrium, gadolinium, and ytterbium and where the composition and structure of the ceramic phosphor is determined by magic angle spinning NMR as opposed to electron dispersive X-Ray (EDX) analysis which, when carried out, yields at best an elemental composition but not the actual chemical structure of the luminescent materials; s is equal to or greater than 0 and less than or equal to 1; x is 0.01 to about 1.0%; and M is an alkali or alkaline earth metal is suspended as an emulsion with a polymer binder such as polyvinyl alcohol or more polyvinylpyrrolidone-polyvinyl acetate and applied to the inner wall of the chamber as already described. A suspension of titanium dioxide is applied to the outer wall of the chamber and similarly polymerized to form a robust scattering layer; after which the chamber is used to assemble the LED lamp. Thus, the present invention includes using two-phase phosphors; a method of applying these two-phase phosphors to the chamber that coats the inner surface of the chamber and which said chamber is ultimately containing a vacuum or a gas selected from ammonia or other Lewis base, nitrogen, argon, xenon, and or krypton to make a LED lamp, with scattering particles therein to produce achromatic light emanating from a Lambertian surface.

[0267] In one embodiment, a protective layer comprising Al2O3, Y2O3 or a rare-earth oxide should be applied between the inner side of the chamber and the phosphor layer.

[0268] In one embodiment, the down-converting material on the interior of the second enclosure 111 comprises a blue fluorescer (Lumogen® F Violet 570—substituted napthalenetetracarboxylic diimide), a green, yellow fluorescer (Lumogen® F Yellow 083—substituted perylenetetracarboxylic diimide) and a red fluorescer (Lumogen® F Red 300—substituted perylenetetracarboxylic diimide). At the same time, on the exterior wall 113, of the second enclosure 111 is coated an inorganic phosphorescent phosphor such as the spinel europium doped strontium aluminate SrAl2O4:Eu. A composition comprising such blue, green-yellow, and red fluorescent materials, all organic based, incorporated within chamber 111, is adjusted by virtue of adjusting the concentration of materials, to match the CIE coordinates of the inorganic europium doped strontium aluminate film on the outer wall of the second enclosure 111. In this manner, the operational performance of the solid-state device is prolonged by virtue of two identical luminescent elements of differing operations but identical photopic response. Further, with removal of electrical current the excited states of spinel europium doped strontium aluminate SrAl2O4:Eu continues to provide chromatic illumination.

[0269] In one embodiment, the down-converting material on the interior of the second enclosure 111 comprises a ceramic phosphor such as Ce3+ doped yttrium aluminum garnet film on the inner wall of the second enclosure 111. At the same time, on the exterior wall 113, of the second enclosure 111 is coated an inorganic phosphorescent phosphor such as the spinel europium doped strontium aluminate SrAl2O4:Eu. In this manner, the operational performance of the solid-state device is prolonged by virtue of two identical luminescent elements of differing operations. Further, with removal of electrical current the excited states of spinel europium doped strontium aluminate SrAl2O4:Eu continues to provide green or yellow-green chromatic illumination.

[0270] In one embodiment, the down-converting material on the interior of the second enclosure 111 comprises a ceramic phosphor such as Ce3+ doped yttrium aluminum garnet film on the inner wall of the second enclosure 111. At the same time, on the exterior wall 113, of the second enclosure 111 is coated an inorganic phosphorescent phosphor such as the strontium sulfide (SrS) activated with divalent europium or SrS:Eu doped with any trivalent rare earth ions, such as holmium (Ho), erbium (Er), neodymium (Nd) and the like. In this manner, the operational performance of the solid-state device is prolonged by virtue of two identical luminescent elements of differing operations. Further, with removal of electrical current the excited states of strontium sulfide continue to provide red chromatic illumination.

[0271] Both gallium nitride and silicon carbide LEDs are suitable for generating light at appropriate wavelengths and of sufficiently high energy and spectral overlap with absorption curves of the down-converting medium. In the case where radiative energy transfer is implemented, the LED is selected to emit most efficiently in regions where luminescent dyes may be usefully employed to absorb wavelengths compatible with readily commercially available fluorescers and/or phosphors for down conversion to achromatic or chromatic light. In the case where non-radiative energy transfer between the excited state of the hole-electron recombination and the ground state of the luminophors in the luminophoric medium is implemented, the LED is selected to allow the wavefunctions that define the excited states formed by hole-electron recombination to integrally overlap with the wavefunctions that define the excited states of the fluorescers and or phosphors used in the luminophoric medium. In the case where non-radiative energy transfer between the excited state of at least one luminophor in the luminophoric medium, a luminophor of the first kind, and the ground state of at least one other luminophor in the luminophoric medium, a luminophor of the second kind, is implemented, the luminophor of the first kind is selected to allow the wavefunctions that define the excited state of the luminophor of the first kind to integrally overlap with the wavefunction that defines the excited state of the fluorescers and or phosphors used as the luminophor of the second kind.

[0272] The luminophoric medium utilized in the light emitting assembly of the present invention thus comprises a down-converting material which may include suitable luminescent dyes which absorb the radiation emitted by the LED or other solid-state device generating the primary radiation, to thereby transfer the radiation energy to the fluorescer(s) and/or phosphor(s) for emission of white light. Alternatively, the luminophoric medium may comprise simply the fluorescer(s) and/or phosphor(s), without any associated mediating material such as intermediate luminescent dyes, if the fluorescer(s) and/or phosphor(s) are directly excitable to emit the desired white light. It is preferential in at least some exemplary embodiments that at least portions of the luminophoric medium be enclosed with second enclosure 111 although certain elements of the luminophoric medium may be external to the second enclosure as long as some of the luminophoric medium is internal to the second enclosure.

[0273] The light emitting assembly shown in FIG. 2, has the same general structure as is shown in FIG. 1 (with the same reference numerals of corresponding parts for ease of reference), but in place of the semiconductor support being placed within the second enclosure 111, the semiconductor support—but not the semiconductor itself—is external to the second enclosure 111 and therefore also supports the placement of the secondary enclosure. In this embodiment, illustrated in FIG. 2, the light emitting assembly utilizes a fluorescer within the second enclosure 111 that is responsively and radiatively excited by the primary photons from the semiconductor p-n junction. The fluorescer in such embodiment may be either covalently or non-covalently attached to the inner wall 112 of the second enclosure or sequestered within the structural form itself that defines the wall of the second enclosure 1111, and/or coated as an interior film of the fluorescer on the interior wall surface of the housing wall 112. Alternatively, the fluorescer may be in solution and sequestered within the sealed inner chamber of the second enclosure 111 or dispersed in a glass or polymeric matrix sealed sequestered within the sealed inner chamber of the second enclosure, and/or in the vapor state and sequestered within the sealed inner chamber of the second enclosure 111. The material sequestered within the second enclosure 111 protects and enhances the emission of primary light as well as secondary light in contrast to gas sequestered within incandescent lamps which primarily regenerate the incandescent filament. The luminophoric medium may also be physically or chemically attached to the substrate of the diode die or to exposed active layer regions of the die itself.

[0274] Comparing the structures of the FIGS. 1 and 2 assemblies, it is seen that the semiconductor support in the FIG. 1 embodiment is contiguously arranged about the LED die structure in the interior volume of the housing, while the semiconductor support in the FIG. 2 embodiment is disposed in spaced relationship to the LED die structure. It will be apparent that the specific arrangement of the solid state device such as LED 13, relative to the down-converting medium of the assembly and supports, may be widely varied in the broad practice of the invention, it being necessary only that the solid state device functioning as the source of the primary shorter wavelength radiation be in transmitting relationship to the recipient luminophoric medium, so that the latter functions in use to down-convert the transmitted radiation from the solid state device and responsively thereto emit achromatic light or chromatic light or infra-red light. When the luminophoric medium is distant from the active layer of the p-n junction by more than 50 Angstroms, then only radiative energy transfer is operable and non-radiative energy transfer is not possible. In that the invention described in FIG. 2 is not all that different than the implementation described in FIG. 1, it is clear from the previous teachings that many different luminophors and secondary luminescent elements may be used, and that two-diode die may be used as well as one. Therefore, for the sake of simplification but not to otherwise limit the scope of this invention, we will limit our discussion of all the embodiments available when FIG. 2 represents the implementation of this invention better than FIG. 1 and refer those of ordinary skill to the teachings already utilized to describe embodiments of this invention represented by FIG. 1.

[0275] In FIG. 3, the placement of the light emitting diode die within the secondary enclosure 111 is more noticeably described. In this embodiment, the luminescent medium is attached to the inner wall of the secondary enclosure 111 and or to the alumina (sapphire) substrate that defines the diode die. The physical location of dyes or fluorescers specifically formulated into the luminophoric medium internal to the chamber or cavity, which may for example include a ceramic non-luminescent dispersant in which the organic dyes and/or fluorescers are adsorbed and or otherwise dispersible, is not specifically limited, and fitting amount(s) of suitable material(s) for such purpose can be readily determined without undue experimentation, to provide good achromatic, or chromatic light emission (of virtually any tint or hue), as well as a virtually infinite series of chromaticity for all visible hues. In FIG. 3 and in an exemplary embodiment, without limiting the scope of this invention, the down-converting medium is covalently attached to the inner wall of the secondary enclosure 111. In the embodiment where the luminophoric medium is covalently attached to the light emitting diode die as opposed to the inner wall of the secondary enclosure and is immobilized as such to be within 50 Angstroms of the active region of said diode die, then non-radiative energy transfer is affected, and down-conversion occurs without the requirement of radiative energy transfer. An embodiment of the implementation of this invention as described by FIG. 3 is for a gas to be sequestered within the enclosure and for the gas to protect and enhance the primary radiation emanating from the p-n junction and or the secondary luminescent elements. When achromatic light is the desired output of the device described by FIG. 3, down-conversion is an implementation method for generation of achromatic light with down-conversion described completely in this invention and in others. However, the full scope of this invention is not contingent on down-conversion being the sole method of implementation for achromatic light and the invention is still operable regardless of whether the secondary luminescent elements are present in FIG. 3 and regardless of whether achromatic light is the result there from. The device is operable absent the secondary luminescent element and that the device is operable when chromatic light is the desired and resultant output.

[0276] However, one of ordinary skill will note, from the complete teachings of this invention presented herein that the device described in FIG. 3 may contain two diodes die and that the secondary luminescent elements may be activated not by down-conversion but by other processes—thermoluminescence and electro-luminescence being two implementations. When the immobilized and covalently attached secondary luminescent elements are activated by an applied electric field, contacts need to be provided to the secondary luminescent elements although said contacts are not shown in the FIG. 3 for sake of simplicity. Regardless of the mechanism by which a secondary luminescent element is activated, the medium inside the enclosure that provides a protecting and enhancing effect is preferred in at least some exemplary embodiments to be a gas but need not be matter solely of the gaseous state. If a gas, then it is preferred in at least some exemplary embodiments that the gas protect and enhance by exclusion and reduction of oxidative steps which would otherwise degrade and or quench the secondary light emission? For reasons previously taught, it is preferred in at least some exemplary embodiments that the gas be nitrogen, argon, krypton and or xenon and or mixtures thereof. The protecting and enhancing gas may include other gaseous elements that protect and enhance not only the secondary luminescent elements but the p-n junction and the mechanism by which primary light is generated.

[0277] An ultraviolet LED light source suitable for use in the structure of FIG. 1 or FIG. 2 or FIG. 3 may comprise: aluminum gallium indium nitride; aluminum gallium nitride; indium gallium nitride; gallium nitride or any other ultraviolet emitting diode. A blue LED light source may be based on: indium gallium nitride; silicon carbide; zinc selenide; or any other blue light emitting diode source.

[0278] TBP, Coumarin-6 and DCM-1, as described by Kido et al. in European Patent EP 647694, are suitable materials for down conversion of the output of gallium nitride or silicon carbide LEDs. Gallium nitride and its alloys can emit in the spectral range covering the blue and ultraviolet extending from wavelengths of 200 nanometers to approximately 650 nanometers. Silicon carbide LEDs emit most efficiently in the blue at wavelengths of around 470 nanometers.

[0279] If gallium nitride emitters are employed in at least some exemplary embodiments, preferred substrates for the emitters include silicon carbide, sapphire, gallium nitride and gallium aluminum indium nitride alloys, and gallium nitride-silicon carbide alloys, for achieving a proper lattice match. If gallium nitride emitters are employed, the fluorescent and phosphorescent centers may be covalently linked to the substrate surface. If sapphire is the substrate, non-covalent chemical and physical adsorption of the fluorescent and or phosphorescent centers to the sapphire substrate may be employed. If desired or if covalent linkage and or chemical and physical adsorption of the fluorescent and or phosphorescent centers to the substrate on which the gallium nitride device is constructed is disadvantageous, then another layer, such as a silicon dioxide layer may be applied to the substrate or to the gallium nitride so as to provide a platform for the covalent, chemical or physical adsorption of the fluorescent and or phosphorescent centers.

[0280] With ultraviolet or blue light LEDs, aromatic fluorescers may be employed as down-converting emitters. By way of example, suitable fluorescers could be selected from:

[0281] 1) blue luminescent compositions—9,10-diphenylanthracene; 1-chloro-9,10diphenylanthracene; 2-chloro-9,10-diphenylanthracene; 2-methoxy-9,10diphenylanthracene; Lumogen® F Violet 570 (a substituted napthalenetetracarboxylic diimide); Alq2OPh (where Al is aluminum, q is 8-hydroxyquinolate, and Ph is phenyl);

[0282] 2) green-yellow luminescent compositions—9,10-bis(phenyl-ethynyl) anthracene; 2-chloro-9,10-bis(phenyl-ethynyl)-anthracene; Coumarin-5 also known as (7-diethylamino-3-(2′benzothiazoyl-)coumarin); Lumogen® Yellow 083 (a substituted perylenetetracarboxylic diimide); and Mq3 (where M is a Group III metal, such as Al, Ga or In, and q is 8-hydroxyquinolate); and

[0283] 3) red-orange luminescent materials—DCM-1; Lumogen® F Red 300 (a substituted perylenetetracarboxylic diimide); Lumogen® F Orange 240 (a substituted perylenetetracarboxylic diimide); tetraphenyl-naphthalene; zinc phthalocyanine; [benzoyl-thiazoylidene)-methyl]squaraines; tris(bipyridine-ruthenium)2+; and [3]-catenand complexes with copper.

[0284] When luminescent dyes are required that emit towards the red and which are capable of being excited non-radiatively as described more fully elsewhere in my present invention, the dyes may include so-called CyDyes from GE Healthcare: (Fluorophore, Color of fluorescence, Absorption Maximum, Emission Maximum)—Cy3, Orange 550 nm, 570 nm; Cy3.5, Scarlet, 581 nm, 596 nm; Cy5, Far-red, 649 nm, 670 nm; and Cy5.5, Near IR, 675 nm, 694 nm. The Alexa Fluor series of dyes from Invitrogen nay also be used as many have absorption maxima near the maximum of primary radiation emanating from GaN semiconductors. More specifically the dye Alexa Fluor® 430 carboxylic acid, succinimidyl ester may be used to covalently attach to suitably prepared ceramic media and or glass wall enclosures (e.g., amine derivatized) and where said dye absorbs blue light with one maximum at 450 nm. The dye may be used to form a derivatized yttrium aluminum garnet without undue experimentation such that the new composition of matter contains both an inorganic luminescent element, such as a cerium dopant, and an organic luminescent element.

[0285] The luminophoric medium may or may not exist external to the chamber at the same time the luminophoric medium is internal to the chamber. The medium in which the fluorescent and or phosphorescent centers that are external to the chamber may include a polymeric matrix or any other matrix and need not be identical to the medium of the luminophoric medium internal to the cavity or chamber. When the external luminophoric medium contains a ceramic phosphor, it is preferential in at least some exemplary embodiments that the ceramic phosphor be a yttrium aluminum garnet phosphor in general or a Ce3+ doped yttrium aluminum garnet more specifically and that the internal luminophoric center contain, at the same time, a green luminescent fluorescers such as 9,10-bis (phenyl-ethynyl) anthracene. When it is desirable that Ce3+ doped yttrium aluminum garnet be used in intimate contact with 9,10-bis(phenyl-ethynyl) anthracene, then both luminophors, or a new composition of matter that contains the covalent addition of the anthracene to the active oxygen of garnet or other ceramic phosphors, or related chemical and physical adsorption of the former to the latter, are sequestered within the sealed second enclosure 111.

[0286] Even more preferred in at least some exemplary embodiments is to covalently attach an organic fluorescer, such as pyrene, to an inert solid matrix that protects the organic fluorescer, such as a zeolite or if it is preferred that the solid matrix emits light, cerium doped yttrium aluminum garnet. Pyrene with a chemical linker arm such as hexamethylene bromide reacts with aluminum oxide based luminophors such as anhydrous cerium doped yttrium aluminum garnet or strontium aluminate to form a new composition of matter: pyrene-(CH2)6YAG:Ce3+.

[0287] In one embodiment, cerium doped yttrium aluminum garnet prepared according to a well-known method used by many practitioners (Wang et. al., U.S. Pat. No. 6,717,349) is suspended in organic solvent and a red-orange derivative of Lumogen® F Red 300—derivatized with a methylene-acyl-chloride or like linker arm—is suspended in the same solvent. After a suitable period to ensure that all the cerium doped yttrium aluminum garnet is covalently attached to the Lumogen® F Red 300 luminophor with a CH2-CO— linker arm molecularly inserted thereto, and where the linker arm is incorporated into the Lumogen® F Red 300 without undue experimentation (See for example, linker arm procedures as in Reynolds, et. al.; Canadian Patent Application CA 2089087; also M. J. Heller, Canadian Patent Application CA 2123133. An excellent reference for “like linker arm” can be found in Waggoner, et. al.; U.S. Pat. No. 6,673,943; issued date Jan. 6, 2004, and references incorporated therein), red enhanced cerium doped yttrium aluminum garnet, a molecular composition different than the underivatized cerium doped yttrium aluminum garnet is isolated with removal of the reaction solvent. The red enhanced yttrium aluminum garnet composition of matter is suspended in a mixture of a casting polymer and a solvent, and a film is sequestered within the sealed second enclosure 111 of FIG. 2.

[0288] The amount of dyes or fluorescers specifically formulated into the external luminophoric medium, which may for example include a polymeric matrix or other matrix material in which the dyes and/or fluorescers are soluble or dispersible, is not specifically limited, and suitable amount(s) of suitable material(s) for such purpose can be readily determined without undue experimentation, to provide good achromatic, or chromatic light emission (of virtually any tint or hue), as well as a virtually infinite series of chromaticity for all visible hues.

[0289] The amount of dyes or fluorescers specifically formulated into the luminophoric medium internal to the chamber or cavity, which may for example include a ceramic non-luminescent dispersant in which the organic dyes and/or fluorescers are adsorbed and or otherwise dispersible, is not specifically limited, and suitable amount(s) of suitable material(s) for such purpose can be readily determined without undue experimentation, to provide good achromatic, or chromatic light emission (of virtually any tint or hue), as well as a virtually infinite series of chromaticity for all visible hues.

[0290] The concentrations of the fluorescers may suitably be determined by both their luminescence quantum yields and spectral distribution, as required to define a particular color by its respective chromaticity coordinates, as well as, in the case of radiative energy transfer (but not Forster energy transfer), the absorption extinction coefficients of the associated fluorescer(s). Such fluorescers may for example be blue light fluorescers used with a blue-emitting semiconductor-based LED die, or ultraviolet light fluorescers used with a UV-emitting semiconductor-based LED die. While the concentrations of the various dyes may be suitably adjusted to realize the required colors, the range of dye concentrations typically will be between 10-3 to 10 mole percent for each individual fluorescent component.

[0291] The light-emitting assemblies shown in FIGS. 1 and 2 and 3 may be made in any suitable size and dimensional character. In application to displays, such light emitting assemblies will generally be of a size commensurate with the size of fluorescent or incandescent lamps used in similar displays.

[0292] Referring more specifically to FIG. 4, only the down-converting medium is placed within a secondary enclosure and this arrangement is sufficient to protect the down-converting medium from deleterious elements. More specifically, a light emitting assembly may be constructed according to the design of FIG. 3 and at the same time additional down-converting medium—as a luminescent element—may be protected according to the design of FIG. 4.

[0293] The following method is sufficient to coat a ceramic phosphor onto the inner wall of the secondary enclosure:

[0294] 1. An aqueous solution of polyvinyl alcohol (PVA) is made by adding 5 grams of PVA powder to 200 ml of water. The mixture is heated to 85° C. with stirring for one hour, then cooled to room temperature, and refrigerated at 2° C. overnight.

[0295] 2. YAG:Ce (0.75 gram) having a particle size of from about 2-9 microns, is added to 1.5 ml of the above solution, and shaken for 5 minutes to form a phosphor slurry.

[0296] 3. The slurry is applied with a micro syringe or an injection nozzle to inner wall of a secondary enclosure. The typical volume of the phosphor slurry applied to each die can be about 1.5 micro liters.

[0297] 4. The secondary enclosure is baked in an oven at 130.degree. C. for 5 minutes to polymerize the binder.

[0298] Another method that may be used to practice the claims of this present invention is using a nanophase binder system as described more completely elsewhere. (M. A. Johnson, et. al.; Canadian Patent Application CA 2330941) The phosphor impregnated binders are coated within the chamber of the present invention where the phosphors selected need not be limited to the luminophors identified by M. A. Johnson et. al. but where the binders identified therein are used to apply phosphors where the phosphors are selected from the embodiments presented in this present invention as disclosed herein.

[0299] Ceramic phosphors used in such a manner may also include those from Nemoto Chemie Co., Ltd.; Tokyo 167-0043, Japan: CaAl2O4:Eu2+, Nd3+ (blue emitter with an emission maximum at 440 nm; excitation peak at 325 nm);

[0300] SrAl14O25:Eu2+, Nd3+ (blue-green emitter with an emission maximum at 490 nm; excitation peak at 365 nm); SrAl2O4:Eu2+, Nd3+ (green emitter with an emission maximum at 530 nm; excitation peak at 365 nm).

[0301] In one embodiment, the red, green and or blue luminophors when using an ultraviolet LED die or 1) red and green or 2) red, green and yellow, or 3) red, green yellow and blue, or 4) red, green blue, yellow and cyan luminophors are printed onto the surface of the protecting and enhancing envelope using ink-jet printing where the image of colored luminescent inks is optimized to create the appearance of white light from all viewing angles and or all angle on which the light falls on to a surface.

[0302] In one embodiment, the red, green and or blue luminophors when using an ultraviolet LED die or 1) red and green or 2) red, green and yellow, or 3) red, green, yellow and blue, or 4) red, green blue, yellow and cyan luminophors are printed onto the surface of the protecting and enhancing envelope using ink-jet printing and where the enhancing envelope is replaceable and interchangeable at will. In this case, for example a white light LED lamp utilized in an automobile, the light will last as long as the functioning of the LED die and the changes in color over time can be immediately reversed by inserting a replacement enhancing envelope or chamber containing different and newer luminescent elements.

[0303] FIG. 5, FIG. 6 and FIG. 7 show a lighting fixture when so arraigned in accordance with the present disclosure: it comprises a plurality of light-emitting diodes in a plurality of light-emitting diode arrays mounted on a board and when connected to a power supply provides luminance—measured at the surface of the optically-transmissive enclosure—up to 270 degrees (e.g., and not 360 degrees). In at least some exemplary embodiments, this lighting fixture has a removable cover to allow mounting of the base of the fixture to a flat surface such as a wall or a ceiling. The lighting fixture may be called a luminaire. The luminaire is defined for example, as herein used, as the entire construction around the light source. It may consist of several components such as mounting, lamp-holder, reflector, shade and or cover. Inside the luminaire is the actual light source, which is called the illuminant. Not all components mentioned may be included in the final construction for the assembly to be a luminaire. The light-emitting diode arrays are the illuminant. Each array is separately powered by leads dispersed in a polymer matrix and connected to each light-emitting diode in one array.

[0304] We refer to one embodiment as shown in FIG. 7 (e.g., including 7005 and 7007) whereby in at least some exemplary embodiments the panel-facings 7001, 7002 and 7003 collectively comprise the at last one optically transmissive enclosure which is removable from the metal base 7004 to which the combination of both is the outer enclosure which form the outer boundary of the light fixture. The optically transmissive panel-facings which form the optically transmissive enclosure may be of glass or of plastic and may be permanently connected to each other, as of one piece, or maybe separate pieces so as when assembled, together, form the bottom part of the overall enclosure.

[0305] In FIG. 7 in at least some exemplary embodiments, the metal base 7004 for the topmost portion of the enclosure and is normally used in a way it is mounted on a wall or a ceiling or some other optically opaque surface. One embodiment of the lighting fixture is shown in a two-dimensional view in FIG. 6, looking perpendicular to the fixture as if mounted on a wall or a ceiling. From this perpendicular perspective, the metal base 601 which forms part of the outer boundary of the lighting fixture occupies a portion (e.g., a minimal portion) of the view when compared with the optically transmissive enclosure 602. The metal base is thermally connected to the board and to the light-emitting diode arrays that form the luminant.

[0306] In at least some exemplary embodiments, inside the outer optically transparent enclosure defined by the outer boundary of the light fixture is the light-emitting diode array represented within FIG. 5. The array in FIG. 5 is 12×10—that there are 12 columns and 10 rows—but the instant invention is not limited to a 12×10 array but by any array that comprises at least 1 column and 2 rows or 2 columns and 1 row. The light-emitting diode array is mounted onto a base and is in thermal connection with a metal base. Thermal connection means for example in the instant invention as hereinbefore described and whereby heat is transferred from the donor to the acceptor (the reservoir in many cases) by conduction, and or convection and or thermal radiation. In this sense, thermal connection means also thermodynamic connection.

[0307] In the case of thermal radiation in at least some exemplary embodiments, the thermal connection between donor and acceptor does not engage the intervening medium or gas. In this sense, engage means involve; does not engage means does not involve. In contrast, convection and conduction does engage the intervening medium or gas. That is, thermal radiation may not involve an intervening medium to carry it. Further, the intervening medium is unchanged as thermal radiation emitted by the donor traverses the medium until it is adsorbed by the acceptor. Hence, in at least some exemplary embodiments, the thermal radiation from the light-emitting diode array does not change the temperature of the inner space or interior space of the enclosures, outer-most and inner-most respectively, unless there is a frequency of radiation tuned to a frequency of absorption of the intervening gas. Thermal radiation emitted by a light-emitting diode is due to acceleration of electrons in the matter that is heated (e.g., electrons in the conduction band of a semiconductor or in the surface interface of an optically opaque fully absorbing material). When any charged particle (such as an electron, a proton, or an ion) accelerates, it radiates away energy in the form of electromagnetic waves. Generally, the thermal radiation is increased when the temperature rises but not necessarily equally over any given ranges of temperatures.

[0308] For the sake of simplicity, only one of the light-emitting diodes, as packaged in an inner enclosure, is shown with a demarcation (i.e., “50010”). The board 50030 (e.g., including 50031, 50032, 50033, and 50034) to which the plurality of light-emitting diodes are thermally connected, is, for example, overlaying the metal base 50020 in FIG. 5. Overlaying is meant convey that 50030 is laid or placed over or upon another (i.e., 50020) to cover. The overlaying may be partial so that electrical leads can be incorporated that ultimately will be connected to a power supply from a distant source and to not interfere with placement of the lighting fixture flush with a wall or a ceiling.

[0309] In at least some exemplary embodiments, the thermal connection is enhanced by using a gas to transport the heat that is formed by a) operating each light-emitting diode due to inefficiencies of recombination of hole and electron pairs at the p-n junction and b) the inevitable reduction in energy, and the heat therefore created to transfer the excess energy, due to the electronic atomic or molecular relaxation of the electronic states populated by blue light (the primary radiation) to the relaxed electronic states which, when populated, yield the down-converted light (the Stokes shift) at the source of the secondary radiation.

[0310] In at least some exemplary embodiments, the source of the Stokes shift may not be adjacent to the p-n junction and may be far away, a so-called far-field energy transfer. If the source of the Stokes shift is a molecular distance away, a so-called near field energy transfer occurs between the p-n junction and the luminophor initiating the down-conversion. For sake of simplicity, the description herein does not highlight any possible reduction in energy due to the scattering of incident primary radiation by intervening matter, such as a luminophor, or a reduction in energy due to so-called self-absorption and radiation imprisonment: both reduction in energy would involve the ultimate dissipation of heat to the external environment.

[0311] In at least some exemplary embodiments, the gas that provides the thermal connection to the metal base and which forms a region of the inner space of the outermost enclosure may be air. It may be a gas such as nitrogen, helium, deuterium, hydrogen, argon, krypton or xenon or any combination thereof including combinations with air. Such gases may be introduced into the outmost optically transmissive enclosure by ways of actuating the entry and exit port 7006 in FIG. 7. The desired gas may be introduced into the inner space of the outer-most enclosure after first creating a vacuum in the same enclosure by connecting a vacuum pump to the same port 7006 and applying a vacuum.

[0312] FIG. 8 shows an array of light-emitting diodes (e.g., each diode would be with the demarcation 805 although for purposes of clarity only one diode is so marked). In at least some exemplary embodiments, the electrical leads transport the current which power the array is shown as 801 and 802, and 804 marks the inner enclosure which comprises both the LED array and the interior space of the inner enclosure. The optically transmissive face of the inner enclosure is with the demarcation of 808. The secondary inner-most enclosure comprises an entry and exit port, with the demarcation of 803, so that the gas can be charged or replenished over time and thereby occupy a region of the interior space. In FIG. 8 the gas that occupies the interior space of the secondary, inner-most enclosure, is shown as H2 (hydrogen molecular) gas and Deuterium gas. It may be a gas such as nitrogen, helium, argon, krypton or xenon or any combination thereof including combinations with air.

[0313] The luminophor for down-conversion may be adjacent to the inner side of face 808 whereby it is exposed to the atmosphere of the interior space; or it may be located adjacent to the outer side of face 808 whereby it is exposed to the atmosphere of the inner space of the outermost-enclosure. In either case, the luminophor may be within or impregnate a polymer film that subsequently is applied to the inner or outer face of 808, the “inner” face for example meaning that which is in the interior of enclosure 804 and outer meaning for example that which is in the exterior of enclosure 804. If the luminophor is comprised of a polymeric film, simply an adsorbed film of sufficient optical path, the luminophor may be oriented into a liquid crystal phase. The enclosure 804 may polarize radiation.

[0314] The ports 803 and 7006 may be used to introduce other inert gases such as perfluorobutane, perfluoropropane, hexafluoroethane, or carbon dioxide.

[0315] In at least some exemplary embodiments, the luminophors may be spun onto the inner or outer of the optically transmissive face 808 such that the luminophors are a mixture of inorganic nanocrystals and aromatic organic fluorescent materials. The luminophors may also be spun as a layer onto the inner face of optically transmissive enclosure 7001. In one embodiment of the instant invention, the luminophor is covalently attached to an optically transmissive face of an enclosure through siloxane chemical bonds when the face is made of glass. In one embodiment, there may be an essentially flat optically transmissive face so that an oriented layer of luminophors are laid upon the face so that the luminescent state has an optical activity associated with its environment. In another embodiment, a plurality of single layers of different luminophors are laid upon the optically transmissive face. As shown in FIG. 8, both hydrogen gas and its stable isotope analog, deuterium gas, are a mixture and demonstrate using a mixture of gases to provide cooling, to transport heat away, from the array through the interior space to the inner space of the outer-most enclosure.

[0316] In one embodiment of the instant invention, each light-emitting diode array is of the same color of primary radiation; in another embodiment a plurality of light-emitting diode arrays are of the same color of primary radiation; in another embodiment, each light-emitting diode array is of a different color of primary radiation than that of the array to which it is adjacent.

[0317] In one embodiment of the instant invention, a text message, such as “OPEN” or “CLOSED” is imprinted onto the external face of the outermost optically transmissive enclosure with a luminescent ink so that the color as seen by a human observer is different than the color of the luminance emitting from the optically transmissive face that is not imprinted.

[0318] In one embodiment of the instant invention, the gas introduced into an enclosure may be a luminescent gas when its absorption spectrum overlaps with the emission spectrum of the primary radiation. By usage of the entry and exit ports, and the initial preparation of an evacuated space and then the introduction of a gas vapor, the gas so entrained may be a liquid at atmospheric pressure but a gas in a region that is a partial vacuum. An example of a luminescent gas is hexafluoro-acetone. As with Hg vapor, it is best to permanently entrain the hexafluoro-acetone vapor inside a permanently sealed chamber or enclosure, e.g. a non-glass chamber.

[0319] In one embodiment, the metal base, in thermal contact with the gas in the inner space and in contact with the secondary enclosures that comprise of light emitting diodes, through which heat is transferred away, from the aforementioned, by conduction, is comprised of steel or another metal imprinted with non-electrical conducting boron-containing metals or electrical conducting copper-containing metals.

[0320] In one embodiment, the light-emitting diode arrays emit blue light and the optically transmissive outer enclosure contains a red colorant.

[0321] In one embodiment, the light emitting diode arrays comprise LED dies that emit visible blue primary radiation and visible red primary radiation as determined by a human observer.

[0322] Further, while the invention has been described primarily herein in reference to the generation of white light, it will be apparent that the scope of the invention is not thus limited, but rather extends to and encompasses the production of light of other colors than mixed white light, utilizing solid state primary radiation emitters, and down converting luminophoric media.

[0323] Thus, while the invention has been described with reference to various illustrative embodiments, features, aspects, and modifications, it will be apparent that the invention may be widely varied in its construction and mode of operation, within the spirit and scope of the invention as hereinafter claimed.