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WO2016039817A1 - Sources lumineuses à del à préférence de couleur augmentée, utilisant du silicate, du nitrure et des substances fluorescentes à base de pfs - Google Patents

Sources lumineuses à del à préférence de couleur augmentée, utilisant du silicate, du nitrure et des substances fluorescentes à base de pfs Download PDF

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WO2016039817A1
WO2016039817A1 PCT/US2015/025128 US2015025128W WO2016039817A1 WO 2016039817 A1 WO2016039817 A1 WO 2016039817A1 US 2015025128 W US2015025128 W US 2015025128W WO 2016039817 A1 WO2016039817 A1 WO 2016039817A1
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Prior art keywords
light source
composite light
phosphor
range
lpi
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Inventor
Kevin James VICK
Gary Robert Allen
Ashfaqul I. Chowdhury
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Current Lighting Solutions LLC
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GE Lighting Solutions LLC
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Priority claimed from PCT/US2014/054868 external-priority patent/WO2015035425A1/fr
Application filed by GE Lighting Solutions LLC filed Critical GE Lighting Solutions LLC
Publication of WO2016039817A1 publication Critical patent/WO2016039817A1/fr
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7766—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals
    • C09K11/7774—Aluminates
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/61—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements
    • C09K11/617—Silicates
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
    • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source

Definitions

  • the present disclosure generally relates to providing light sources that emit light having enhanced color spectrum characteristics such that human observers perceive enhanced color preference.
  • Reveal ® is a trademarked term used by the General Electric Company to refer to light sources, such as a light bulb, having enhanced red-green color contrast lighting characteristics and enhanced whiteness relative to an unmodified incandescent or halogen light source.
  • Reveal ® incandescent and halogen bulbs filter light by placing a particular type of glass (namely, glass impregnated with neodymium (Nd) oxide) in front of the light emitted by the filament to absorb some of the yellow light.
  • the glass impregnated with Nd oxide causes a "depression" in the yellow region of the color spectrum, so that objects viewed under this light have an enhanced color contrast, especially red and green objects which are contrasted readily by an observer, such as a person in a room of a house.
  • the removal of some yellow light via the filter also shifts the location of the chromaticity on the 1931 International Commission of Illumination (Commission Internationale de l’Éclairage, or CIE) color diagram to a point slightly below the blackbody locus, which generally creates the impression of whiter light to most observers.
  • CIE International Commission of Illumination
  • FIG. 1a provides a graph of three color matching functions, known as the XYZ tristimulus values that represent the chromatic response of a standard observer.
  • the perceived color of an object is determined by the product of the illumination source spectrum, the reflectance spectrum of the object, and the three color matching functions. These functions are related to the response of the photoreceptors in the human eye, and can be thought of as the perception of blue (102), green (104), and red (106) light.
  • FIG. 1b provides a graph for a product of a standard incandescent spectrum with the color matching functions for blue (132), green (134), and red (136) responses.
  • FIG. 1c provides a graph for a product of a reveal ® incandescent spectrum with the color matching functions for blue (162), green (164), and red (166) responses.
  • the green (164) and red (166) components are more distinct, with a peak separation of 53 nm, as compared to the red and green components of FIG. 1b. This distinction allows observers to more easily distinguish reds and greens with greater contrast and results in a more saturated appearance when yellow light is suppressed.
  • SSL light sources for example LEDs or organic light-emitting diodes (OLEDs), may produce light directly from the semiconductor, e.g. a blue or red or other colored LED. Alternatively, the light may be produced by conversion of the high-energy light from the SSL, e.g.
  • a blue or violet LED by a down- converter such as a phosphor or quantum dot or other energy converting material.
  • a down- converter such as a phosphor or quantum dot or other energy converting material.
  • CRI color rendering index
  • color quality metrics can be broken down into three broad categories pertaining to their intent and method of calculation: fidelity, discrimination, and preference.
  • Fidelity metrics which include CRI, quantify an absolute difference from a reference illuminant, regardless of whether the test illuminant is perceived as being better or worse than the reference illuminant, and without consideration to whether the reference illuminant is actually preferred by most observers.
  • Discrimination metrics quantify the total area of color space that may be rendered under the test illuminant, and are maximized at extreme levels of saturation and hue distortion.
  • the existing color preference metrics have been developed to provide a quantitative measure of user color preference, but none provides a sufficient correlation to observer data, along with a target value to enable optimization of a light source; therefore, the metric cannot be used as a target parameter in a design optimization.
  • Some of the more well-known metrics in the color preference category include Flattery Index (R f ), Color Preference Index (CPI), and Memory Color Rendering Index (MCRI). All three of these metrics have "ideal" configurations for the chromaticity coordinates of eight to ten test color samples, and each quantifies the deviation from these target values.
  • the Flattery Index was the first metric to target preference and used ten color samples with unequal weighting.
  • CPI Color Rendering Index
  • the target chromaticity shifts were reduced to one-fifth of their experimental values, greatly reducing its correlation with observer responses to color preference.
  • CPI maintained the experimental values for preferred chromaticity shifts, resulting in a better representation of color preference.
  • CPI is very limited in its selection of test color samples, using the same eight, unsaturated test colors as CRI.
  • Solid-state lighting technologies such as LEDs and LED-based devices often have superior performance when compared to incandescent lamps. This performance may be quantified by the useful lifetime of the lamp, lamp efficacy (lumens per watt), color temperature and color fidelity, and other parameters.
  • Commercial lamp types including incandescent, halogen, and LED employing Nd- doped glass to absorb some of the yellow light from the spectrum emitted by the light source may enhance the color preference relative to their counterpart lamps without the Nd absorption.
  • GE Lighting and some other manufacturers, has products of each of these three types. The GE Lighting products have the reveal ® brand name.
  • CFL compact fluorescent
  • LFL linear fluorescent
  • LED lamps are known to enhance the color preference relative to their counterpart lamps that employ standard phosphors.
  • GE Lighting has products of each of the first two types, also under the reveal ® brand name.
  • LED light sources of the third type are known, for example in grocery applications to enhance the colors of meats, vegetables, and produce (e.g. fruit).
  • Each of these existing light sources has employed either Nd-doped glass, or customized phosphors that reduce the amount of yellow light emitted by the light source in order to enhance color preference.
  • Nd-doped glass or customized phosphors that reduce the amount of yellow light emitted by the light source in order to enhance color preference.
  • the Nd filter in these existing light sources may typically be comprised of Nd 2 O 3 - doped glass.
  • the yellow filter may be comprised of one of several other compounds of Nd or of Didymium (a mixture of the elements praseodymium and Nd) or other rare earths that preferentially absorb yellow light, embedded in various matrix host materials, for example glass, crystal, polymer, or other materials; or by some other dopant or coating on the glass that absorbs preferentially in the yellow range of wavelengths; or by the addition of any yellow absorber to any of the optically active components of the lamp or lighting system, such as a reflector or diffuser or lens, which may be a glass or polymer or metal or any other material that accommodates the yellow absorber.
  • a reflector or diffuser or lens which may be a glass or polymer or metal or any other material that accommodates the yellow absorber.
  • the exact peak wavelength and width of the yellow absorption may vary depending on the particular Nd or rare-earth compound and host material, but many combinations of Nd, Didymium and other rare-earth compounds and host materials may be suitable substitutions for the combination of Nd 2 O 3 -doped glass, as are some other yellow filters.
  • the Nd or other yellow filter may be in the shape of a dome enclosing the light source, or may be any other geometric form enclosing the light source, such that most or all of the light in the yellow range of wavelengths passes through the filter.
  • a composite light source includes at least one blue light source having a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm; at least one silicate phosphor; at least one narrow red down-converter (i.e., narrow-band red-emitting down-converter); and wherein the composite light source has a Lighting Preference Index (LPI) of at least 120.
  • LPI Lighting Preference Index
  • a composite light source includes at least one blue light source having a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm; at least one silicate phosphor; at least one narrow red down-converter; and wherein the combined coordinate of (Dom Sil , Duv) falls within a quadrilateral defined by four vertices of (531– 0.004*CCT, -0.0105), (569– 0.004*CCT, 0.0010), (587– 0.004*CCT, -0.0095), and (560– 0.004*CCT,-0.0210), where Duv is a measure of the whiteness of the composite light source and Dom Sil is the dominant wavelength of the at least one silicate phosphor.
  • a composite light source includes at least one blue light source having a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm; at least one silicate phosphor; at least one broad red down-converter (i.e., broad-band red- emitting down-converter); and wherein the composite light source has a Lighting Preference Index (LPI) of at least 125.
  • LPI Lighting Preference Index
  • a composite light source includes at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm; at least one silicate phosphor; at least one narrow red down-converter; at least one broad red down-converter; and wherein the composite light source has a Lighting Preference Index (LPI) of at least 120.
  • LPI Lighting Preference Index
  • FIG. 1a illustrates a graph of the three color matching functions, the XYZ tristimulus values, or the chromatic response of a standard observer.
  • FIG. 1b illustrates a graph of the products of the three color matching functions with the spectrum for a standard incandescent lamp.
  • FIG. 1c illustrates a graph of the products of the three color matching functions with the spectrum for a reveal® incandescent lamp.
  • FIG. 2 illustrates a chart displaying the percentage of observers that selected each LED system.
  • FIG. 3 illustrates a graph of the "White Line” (sometimes also called the “white-body curve” or“white-body locus”) and a graph of the blackbody curve (or blackbody locus, or BBL).
  • White Line sometimes also called the "white-body curve” or“white-body locus”
  • BBL blackbody locus
  • FIG. 4a illustrates the ten main categories of hue in the a*-b* chromaticity plane, as prescribed in the Munsell classification system for color.
  • FIG. 4b illustrates the radial and azimuthal components in the a*-b* chromaticity plane that comprise each Color Rendering Vector.
  • FIG. 4c illustrates the Color Rendering Vectors (CRVs) at Munsell value 5 for a neodymium incandescent lamp.
  • FIG. 5 illustrates an incandescent or halogen light source.
  • FIG. 6a illustrates a graph of the relative light output versus wavelength (or the spectral power distribution (SPD)) of an incandescent light source of FIG. 5, and a blackbody light source.
  • SPD spectral power distribution
  • FIG. 6b illustrates a graph including a plot of the SPD of an incandescent light source, and a plot of the SPD of a reveal ® type incandescent light source.
  • FIG. 7a illustrates a reveal ® type LED light source that includes one or more LEDs.
  • FIG. 7b is an exploded view of the light source of FIG. 7a.
  • FIG. 8 illustrates a graph including a plot of the SPD of a warm-white LED lamp comprising multiple blue LEDs each exciting a YAG phosphor and a red phosphor, and a plot of the SPD of a reveal ® type LED light source.
  • FIG. 9 illustrates a reveal ® type compact fluorescent (CFL) light source.
  • FIG.10 illustrates a graph including a plot of the spectral power distribution (SPD) of a reveal® type CFL light source, and a plot of the SPD of a reveal® type incandescent light source.
  • FIG. 11 illustrates a graph of the SPD of a known light source having green and red phosphors having peak wavelengths separated sufficiently to produce a depression in the yellow wavelength range.
  • FIG.12 illustrates a graph of the SPD of a conventional LED light source.
  • FIG. 13 illustrates a graph of the SPD of the blue LED of a light source according to some embodiments.
  • FIG. 14 illustrates a graph of the SPDs of five different green silicate phosphors according to some embodiments.
  • FIG. 15 illustrates a graph of the SPDs of four different broad red (BR) nitride phosphors according to some embodiments.
  • FIG. 16 illustrates the emission spectrum of a narrow red (NR) phosphor according to some embodiments.
  • FIG. 17a illustrates the color coordinates in the 1931 CIE color system of the CIE standard illuminant D65, the color point of the green phosphor“Silicate 1” of FIG. 14, and the point on the spectrum locus (the perimeter of the CIE color space) of the resultant dominant wavelength of“Silicate 1” according to some embodiments.
  • FIG. 17b illustrates the color coordinates in the 1931 CIE color system of the blue LED of FIG. 13, the five green silicate phosphors of FIG. 14, and the NR phosphor of FIG. 16 according to some embodiments.
  • FIG. 17c illustrates the color coordinates in the 1931 CIE color system of the blue LED of FIG. 13, the five green silicate phosphors of FIG. 14, and the four different BR nitride phosphors of FIG. 15 according to some embodiments.
  • FIG. 18a illustrates the color coordinates in the 1931 CIE color system of the five commercially available green silicate phosphors of FIG. 14, and also of a modification of each of the five green silicate phosphors, where the peak wavelength is shifted by +10 nm, +5 nm, -5 nm, and–10 nm as appropriate, providing a total of 23 SPDs representing a systematically parameterized, broad range of different green silicate phosphors according to some embodiments.
  • FIG. 18b illustrates the color coordinates in the 1931 CIE color system of the 23 systematically parameterized green silicate phosphors of FIG. 18a, and also of 10
  • FIG. 19a illustrates the color coordinates in the 1931 CIE color system of the four broad red nitride phosphors of FIG. 15, and also of a modification of each of the four broad red nitride phosphors, where the peak wavelength is shifted by +10 nm, +5 nm, -5 nm,–10 nm, providing a total of 20 SPDs representing a systematically parameterized, broad range of different broad red nitride phosphors according to some embodiments.
  • FIG. 19b illustrates the color coordinates in the 1931 CIE color system of the 20 systematically parameterized broad red nitride phosphors of FIG. 19a, and also of 14 presently commercially available broad red nitride phosphors according to some
  • FIG. 20 illustrates the relationship between the peak wavelengths and the dominant wavelengths of the 23 systematically parameterized green silicate phosphors of FIG. 18a according to some embodiments.
  • FIG. 21 illustrates the relationship between the peak wavelengths and the dominant wavelengths of the 20 systematically parameterized broad red nitride phosphors of FIG. 19a according to some embodiments.
  • FIG. 22a illustrates the contour plot of Lighting Preference Index (LPI) versus dominant wavelength of the green silicate phosphor on the x-axis, and the location of the color point of the light source in the CIE 1960 u-v color space, relative to the BBL at 2700 K, as quantified by Duv on the y-axis, where the red emitter is the NR phosphor of FIG. 16 according to some embodiments.
  • LPI Lighting Preference Index
  • FIG. 22b illustrates the contour plot of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and the location of the color point of the light source in the CIE 1960 u-v color space, relative to the BBL at 3000 K, as quantified by Duv on the y-axis, where the red emitter is the NR phosphor of FIG. 16 according to some embodiments
  • FIG. 23 illustrates the discrete runs represented by the dominant wavelength of the green silicate phosphor, and by Duv, overlaid on the contour plot of the LPI response from FIG. 22a, where the red emitter is the NR phosphor of FIG. 16 according to some
  • FIG. 24 illustrates the SPD of the discrete run having the highest LPI value for a light source comprising a blue LED, a green silicate phosphor, and a NR phosphor at 2700 K according to some embodiments.
  • FIG. 25a illustrates a family of analytic approximations to each of the LPI contours at 2700 K from FIG. 22a where the red emitter is the NR phosphor of FIG. 16, overlaid on the actual LPI contours according to some embodiments.
  • FIG. 25b illustrates a family of analytic approximations to each of the LPI contours at 3000 K from FIG. 22b where the red emitter is the NR phosphor of FIG. 16, overlaid on the actual LPI contours according to some embodiments.
  • FIGS. 27a-h illustrate the contour plots at 2700 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is the broad red nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 27a), 620 nm (FIG. 27b), 630 nm (FIG. 27c), 640 nm (FIG. 27d), 650 nm (FIG. 27e), 660 nm (FIG. 27f), 670 nm (FIG. 27g), 680 nm (FIG. 27h) according to some embodiments.
  • the red emitter is the broad red nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 27a), 620 nm (FIG. 27b), 630 nm (FIG. 27c), 640 nm (FIG. 27d), 650
  • FIGS. 28a-h illustrate the contour plots at 3000 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is the broad red nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 28a), 620 nm (FIG. 28b), 630 nm (FIG. 28c), 640 nm (FIG. 28d), 650 nm (FIG. 28e), 660 nm (FIG. 28f), 670 nm (FIG. 28g), 680 nm (FIG. 28h) according to some embodiments.
  • the red emitter is the broad red nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 28a), 620 nm (FIG. 28b), 630 nm (FIG. 28c), 640 nm (FIG. 28d), 650
  • FIG. 29 illustrates the SPD of the discrete run having the highest LPI value for a light source comprising a blue LED, a green silicate phosphor, and a broad red nitride phosphor at 2700 K according to some embodiments.
  • FIGS. 30a-h illustrate the contour plots at 2700 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is comprised of 75% the NR phosphor of FIG. 16 and 25% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 30a), 620 nm (FIG. 30b), 630 nm (FIG. 30c), 640 nm (FIG. 30d), 650 nm (FIG. 30e), 660 nm (FIG. 30f), 670 nm (FIG. 30g), 680 nm (FIG. 30h) according to some embodiments.
  • the red emitter is comprised of 75% the NR phosphor of FIG. 16 and 25% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 30a), 620 nm
  • FIGS. 31a-h illustrate the contour plots at 3000 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is comprised of 75% the NR phosphor of FIG. 16 and 25% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 31a), 620 nm (FIG. 31b), 630 nm (FIG. 31c), 640 nm (FIG. 31d), 650 nm (FIG. 31e), 660 nm (FIG. 31f), 670 nm (FIG. 31g), 680 nm (FIG. 31h) according to some embodiments.
  • the red emitter is comprised of 75% the NR phosphor of FIG. 16 and 25% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 31a), 620 nm
  • FIG. 32 illustrates the SPD of the discrete run having the highest LPI value for a light source comprising a blue LED, a green silicate phosphor, and a red emitter comprised of 75% NR phosphor and 25% BR nitride phosphor at 2700 K according to some embodiments.
  • FIGS. 33a-h illustrate the contour plots at 2700 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is comprised of 50% the NR phosphor of FIG. 16 and 50% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 33a), 620 nm (FIG. 33b), 630 nm (FIG. 33c), 640 nm (FIG. 33d), 650 nm (FIG. 33e), 660 nm (FIG. 33f), 670 nm (FIG. 33g), 680 nm (FIG. 33h) according to some embodiments.
  • the red emitter is comprised of 50% the NR phosphor of FIG. 16 and 50% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 33a), 620 nm (FI
  • FIGS. 34a-h illustrate the contour plots at 3000 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is comprised of 50% the NR phosphor of FIG. 16 and 50% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 34a), 620 nm (FIG. 34b), 630 nm (FIG. 34c), 640 nm (FIG. 34d), 650 nm (FIG. 34e), 660 nm (FIG. 34f), 670 nm (FIG. 34g), 680 nm (FIG. 34h) according to some embodiments.
  • the red emitter is comprised of 50% the NR phosphor of FIG. 16 and 50% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 34a), 620 nm (FI
  • FIG. 35 illustrates the SPD of the discrete run having the highest LPI value for a light source comprising a blue LED, a green silicate phosphor, and a red emitter comprised of 50% NR phosphor and 50% BR nitride phosphor at 2700 K according to some embodiments.
  • FIGS. 36a-h illustrate the contour plots at 2700 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is comprised of 25% the NR phosphor of FIG. 16 and 75% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 36a), 620 nm (FIG. 36b), 630 nm (FIG. 36c), 640 nm (FIG. 36d), 650 nm (FIG. 36e), 660 nm (FIG. 36f), 670 nm (FIG. 36g), 680 nm (FIG. 36h) according to some embodiments.
  • the red emitter is comprised of 25% the NR phosphor of FIG. 16 and 75% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 36a), 620 nm
  • FIGS. 37a-h illustrate the contour plots at 3000 K of LPI versus dominant wavelength of the green silicate phosphor on the x-axis, and Duv on the y-axis, where the red emitter is comprised of 25% the NR phosphor of FIG. 16 and 75% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 37a), 620 nm (FIG. 37b), 630 nm (FIG. 37c), 640 nm (FIG. 37d), 650 nm (FIG. 37e), 660 nm (FIG. 37f), 670 nm (FIG. 37g), 680 nm (FIG. 37h) according to some embodiments.
  • the red emitter is comprised of 25% the NR phosphor of FIG. 16 and 75% the BR nitride phosphor of FIG. 15 having peak wavelength of 610 nm (FIG. 37a), 620 nm
  • FIG. 38 illustrates the SPD of the discrete run having the highest LPI value for a light source comprising a blue LED, a green silicate phosphor, and a red emitter comprised of 25% NR phosphor and 75% BR nitride phosphor at 2700 K according to some embodiments.
  • FIG. 39 illustrates the LPI achievable at a Duv of about -0.010, a Dom Sil of about 550 nm, and a CCT at 2700 K as a function of the BR nitride peak wavelength for different compositions of the red emitter according to some embodiments.
  • FIGS. 40a-c illustrate a composite light source according to some embodiments. DETAILED DESCRIPTION
  • the term“light source” may mean any source of visible light, e.g. the semiconductor, or LED, or OLED; or the down-converter such as a phosphor or quantum dot; or remote down-converter, or down-converter coated onto or embedded into a reflector or refractor; or a multi-channel combination or composite of several such light sources; or a system such as a lamp or luminaire or fixture comprising such light sources.
  • LPI Lighting Preference Index
  • the enhanced color preference may be due to a combination of enhanced color contrast and enhanced whiteness, and the LPI color metric may enable quantitative optimization of color preference by tailoring the spectral power distribution of the light source.
  • the individual light sources may be commercially available or easily manufactured blue LEDs, green silicate phosphors, broad red nitride phosphors, and narrow red phosphors, but combined in novel ways. This may be in contrast to the light sources described in patent application US 61/875403 and PCT/US2014/054868, incorporated herein by reference, wherein the light sources were represented as combinations of an actual blue LED, plus green and red light sources each represented by Gaussian distribution of wavelength that are characterized by a peak wavelength and a full-width at half-maximum (FWHM).
  • FWHM full-width at half-maximum
  • the light sources of the present disclosure may be combinations of a commercially available blue or violet LED, a green silicate phosphor, and either a broad red nitride phosphor or a narrow red phosphor, or a combination of a broad and narrow red phosphor.
  • a commercially available blue or violet LED may be used.
  • the green phosphor may contain a silicate- based fluorescent material activated by Eu 2+ , which in some embodiments have the general formula A 2 Si 1 -n O 4-2n :Eu 2+ wherein -0.2 ⁇ n ⁇ 0.2 and A is at least one element selected from the group consisting of Sr, Ca, Ba, Mg, Zn, and Cd. This composition will be generally referred to as a silicate phosphor.
  • Red phosphors may be defined for the purpose of this invention as having FWHM in two ranges: narrow FWHM ⁇ about 60 nm; and broad FWHM > about 60 nm.
  • Broad red (BR) nitride materials of the present disclosure may absorb UV and blue light strongly and may emit efficiently between about 600 nm and 670 nm, with FWHM of about 80 nm to about 120 nm, providing very strong emission in the deep red, but at the expense of relatively poor luminous efficacy (lumens per watt, LPW).
  • the BR nitride phosphor is typically represented by the general formula CaAlSiN 3 :Eu 2+ , but others compositions are possible.
  • Narrow red (NR) phosphors of the present disclosure may absorb blue light strongly and may emit efficiently between about 610 nm and 660 nm with little deep red or near-infrared emission.
  • Some such NR phosphors are known, e.g., based on complex fluoride materials activated by Mn 4+ , such as those described in U.S. Pat. No.
  • the Mn 4+ doped phosphors have the formula A x [MF y ]:Mn 4+ wherein A (alkali) is Li, Na, K, Rb, Cs, or a combination thereof; M (metal) is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF y ] ion; y is 5, 6 or 7.
  • a NR phosphor may comprise K 2 [SiF 6 ]:Mn 4+ (manganese-doped potassium fluoro-silicate, termed "PFS") which, when excited by an InGaN blue emitter at about 400 nm to about 460 nm, may generate a strong red emission line at about 631 nm, having a FWHM ⁇ about 10 nm.
  • PFS manganese-doped potassium fluoro-silicate
  • LPI as disclosed herein accounts for both preferred color appearance (saturation and hue distortion) as well as preferred shifts in color point away from the Planckian (blackbody) locus.
  • LPI is a predictive metric that quantifies consumer preference.
  • LPI can be used as a design tool for optimizing spectra for color preference.
  • a strong correlation for LPI has been found with preliminary observer testing, and the optimization capability of LPI as an accurate predictive preference metric is proven through additional studies. In an observer study with 86 participants, four discrete LED systems were designed to different enhanced levels of LPI, ranging from 114 to 143.
  • FIG. 2 illustrates the percentage of observers that selected each LED system as their preferred environment. As shown, the highest percentage of observers (42%) preferred light source D having an LPI of 143, while the smallest percentage of observers (11%) preferred light source A having an LPI of 114.
  • LPI The formula for LPI as described herein is based on an observer set within the age range of 21 to 27 years, with a gender distribution of 58% male and 42% female, a race distribution of 92% Caucasian and 8% Asian, and a geographical distribution within North America.
  • this does not diminish the effectiveness of LPI, as presently defined herein, to quantify and optimize the level of color preference for an arbitrary light source spectrum such that if that test light source is built and the test illuminant is observed by a population having color preferences similar to those of a particular test population, then the test light source will be preferred relative to other light sources that score lower on the LPI scale by that test population.
  • spectra or light sources optimized for high LPI, and having LPI greater than conventional light sources exhibit higher color preference among observers (having similar color preference bias to those in our dataset) than any of the conventional light sources.
  • a variation of the lumen for example the scotopic lumen, is defined that differs from the traditional photopic lumen, and the definition of the scotopic lumen enables the discovery and development of light sources having increased or optimized scotopic lumen efficiency, that would not invalidate the effectiveness of the discoveries and developments of light sources that had provided, and continue to provide, increased or optimized photopic lumens, since the photopic lumen had been rigorously defined, even though it was not universally appropriate in all lighting applications.
  • LPI objectively defines a quantitative color preference metric that most closely correlates with a limited population of observers for which color preference data was available.
  • the LPI metric is a function of two parameters: the Whiteness of the illumination source and the Color Appearance of objects illuminated by the source. The specific LPI function is defined below, after explanation of Whiteness and Color Appearance.
  • Whiteness refers to the proximity of the color point to the "White Line” on the chromaticity diagram, where the“White Line” is described in the following publication: “White Lighting", Color Research & Application, volume 38, #2, pp. 82-92 (2013), authors M.S. Rea & J. P. Freyssinier (henceforth, the "Rea reference”). The Rea reference is hereby incorporated by reference.
  • the“White Line” is defined by the color points in Table 1 below, as reported in CCX and CCY color coordinates for selected color temperatures from 2700 K to 6500 K.
  • the "White Line” 304 (sometimes also called the“white-body line”, “white-body curve”, or“white-body locus”) is slightly above the blackbody curve 302 at high color temperatures (e.g., above 4000 K) and well below it at lower color temperatures. Studies indicate that illumination on the“White Line” may correspond to human perception of what is "white” light.
  • the "White Line” is proposed for a wide range of color temperatures, but for color temperatures between about 2700 K and about 3000 K (these are Correlated Color Temperature (CCT) values that consumers often prefer), the “White Line” is about 0.010 Duv below the blackbody locus, wherein Duv represents the distance from the blackbody locus in u-v chromaticity space.
  • CCT Correlated Color Temperature
  • Duv for purposes of Equation (1), is the distance of the color point from the Planckian locus in u-v space (note: values below the blackbody line are negative in Equation (1)). For example, for a point at 0.010 below the blackbody, one would insert -0.010 into Equation (1).
  • the Whiteness can be approximated by inspection of the position of the color point in FIG. 3, without undue experimentation; e.g., if the illumination source has a color point on the“White Line”, it will similarly have a Whiteness value of unity).
  • LPI increases as the color point of the illumination source approaches the“White Line”, and decreases as it moves away in either direction.
  • Color Appearance is a composite measure of color rendering, which is a function of the Net Saturation Value (NSV) of the illumination source (e.g., relatively higher LPI values are obtained for NSV that show an enhanced saturation, but are not overly saturated), and the Hue Distortion Value (HDV); (e.g., relatively higher LPI values are obtained for HDV that show a minimal or zero hue distortion).
  • NSV Net Saturation Value
  • HDV Hue Distortion Value
  • the lighting preference index (LPI) metric was developed using an unbiased selection of test color samples, by selecting an array of colors using the complete database of 1600 corrected Munsell glossy spectral reflectances. These 1600 colors would be understood by the person of ordinary skill in the art, especially in view of M.W. Derhak & R.S. Berns, "Analysis and Correction of the Joensuu Munsell Glossy Spectral Database," Color and Imaging Conference, 2012(1), 191-194 (2012). Using this array of colors allows for coverage of a significant fraction of color space utilizing the Munsell classification system of hue, value, and chroma.
  • each color in this array is defined by the Munsell system in terms of its hue (which has 10 categories with 4
  • the color points of all 1600 color samples are calculated, as rendered by both the illumination source (i.e., the test illuminant) and by a CIE reference illuminant, or Planckian radiator, at the same color temperature.
  • the CIE reference illuminant has a spectrum which is determined from the CCT of the illumination source, using Planck’s law for blackbody radiation. Planck’s law defines radiance of the light source B (in W/sr ⁇ m 3 ) as a function of wavelength ⁇ (in meters) and absolute temperature where h
  • a blackbody is a physical body that is an ideal absorber, that is, it absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. It is also an ideal emitter: at every frequency, it emits as much energy as– or more energy than– any other body at the same temperature.
  • CIE L*a*b* CIELAB
  • CIELAB color rendering vectors
  • a CRV is a representation of the magnitude and direction of a color appearance shift with respect to the reference illuminant.
  • FIG. 4b illustrates the components contained in each CRV.
  • the radial component 401, or ⁇ C ab quantifies the shift in chroma, or saturation, where shifts away from the origin signify increases in saturation and shifts toward the origin signify decreases in saturation.
  • the azimuthal component 403, or ⁇ h ab quantifies the change in hue and can be represented by an angular change, in radians.
  • FIG. 4c represents the CRVs 402 at Munsell value 5 for a neodymium incandescent lamp, a product commonly preferred by consumers.
  • the neodymium lamp produces enhanced saturation, particularly in the red and green components (at the right and left sides, respectively, of the vector plot).
  • NSV Net Saturation Value
  • Improved levels of saturation are indicated by increases in chroma ( ⁇ C ab > 0) beyond a threshold of average perceptual difference, but below an over-saturation limit. Decreased saturation levels ( ⁇ C ab ⁇ 0) are only counted if chroma is reduced beyond the same threshold of average perceptual difference.
  • the average perceptual difference value is based on the following publication:“Evaluation of Uniform Color Spaces Developed after the Adoption of CIELAB and CIELUV”, Color Research and Application, volume 19, #2, pp. 105-121 (1994), authors M. Mahy, L. Van Eycken, & A. Oosterlinck, which found the average perceptibility radius to be 2.3 in CIELAB space.
  • NSV i Individual NSV values are calculated for the 10 main hue categories in the Munsell system, and a total NSV is taken as the average over the 10 hues.
  • NSV is defined by Equation (2) and Equation (3):
  • Equation (2) [0091] Equation (2):
  • ⁇ C ab is the radial component of the CRV and represents the shift in perceived chroma, or saturation
  • i represents the hue category for the 10 main hue categories of the Munsell system.
  • the change in saturation may not be perceived by a typical observer and is therefore not counted as either improved or worsened.
  • the Hue Distortion Value represents a weighted percentage of test samples that are changing hue. While increased chroma (up to a limit) generally does contribute to attaining relatively higher LPI values, changes in hue are generally undesirable (although changes in hue are a relatively weaker contributory factor to the final LPI value than are chroma changes).
  • the Munsell color system is typically divided into 40 hue subcategories (4 subcategories in each of the 10 main hue categories).
  • ⁇ h ab > ⁇ /20 radians or 1/40 th of a circle
  • ⁇ h ab value is weighted by the average ⁇ h ab value, scaled by the separation between hue sublevels ( ⁇ /20 radians).
  • This additional weighting is used to account for very large amounts of hue distortion, where the percentage alone approaches a limit at very high percentage, as nearly all test colors experience hue distortion of surpassing the threshold to be counted.
  • the direction of hue distortion is unimportant, so ⁇ h ab > 0 for distortion in both the clockwise and
  • HDV i the average over the 10 hues.
  • Equation (4) the average over the 10 hues.
  • Equation (4) [0097]
  • ⁇ h ab is the azimuthal component of the CRV and represents the shift in perceived hue
  • i represents the hue category for the 10 main hue categories of the Munsell system
  • ⁇ h ab value is the average for all colors within hue i.
  • Equation (6) the HDV is weighted (i.e., divided by a factor) relative to NSV to provide the best match to observer preference responses.
  • Equation 7 Equation 7:
  • Equation (1) Whiteness is defined in Equation (1) and Color Appearance is defined in Equation (6).
  • the parameter of“100” is chosen so that a reference blackbody illuminant scores a baseline value of 100 as with other lighting metrics.
  • the weighting factors of 38% Whiteness and 62% Color Appearance have been chosen to provide the best fit to observer preference data.
  • Equation (8) An alternative "master" equation for LPI, which is merely a combination of equations (1), (6) and (7), is shown as Equation (8):
  • the LPI metric may be determined by the following steps (not necessarily in this order):
  • step (c) the whiteness of step (c) is calculated in parallel with the calculation of color appearance in steps (d)-(h). Then the whiteness and color appearance serve as inputs to the final step (i).
  • LPI metric objectively defines a quantitative color preference metric that most closely correlates with a limited population of observers for which color preference data was available
  • color preference may also be quantified using a novel combination of existing color metrics, although with somewhat weaker, but acceptably strong, correlation to color preference data of observers.
  • existing color metrics that separately represent saturation and color point relative to the BBL can be expected to approximate the color preference responses of observers within some limits of color space.
  • LPI furthermore may combine the effects of saturation and color point with an optimal weighting of each to provide a single metric, rather than multiple metrics, which has been validated to be useful as a single-parameter optimization response that enables the design of spectra that will predictively elicit a targeted color preference response from observers.
  • the separation between the peak or dominant wavelength of the green phosphor and the red phosphor provides a close approximation to the color saturation portion of the LPI metric
  • the Duv measure is a close approximation to the color point portion (i.e., whiteness) of the LPI metric.
  • the separation between the peak or dominant wavelength of the green phosphor and the peak wavelength of the red phosphor is quantified by holding the peak wavelength of the red phosphor fixed, while varying the dominant wavelength of the green phosphor, thereby providing a direct measure of the separation between the green and red phosphors.
  • a light source comprising a blue LED, a green silicate phosphor, and a NR or BR phosphor having a given peak wavelength, by the dominant wavelength of the green phosphor, and Duv of the color point in the CIE 1960 u-v color space, as approximate substitutes for the more accurate LPI metric, with the advantage that some practitioners may find it easier to calculate the dominant wavelength of the green phosphor and Duv responses than to calculate the LPI response, even though all of the details necessary to calculate the LPI response have been provided.
  • FIG. 5 illustrates an incandescent light source or halogen light source 500 that includes one or more incandescent or halogen coils 502 within a glass dome 504.
  • the glass dome 504 may be doped with neodymium oxide (Nd 2 O 3 ), as is provided in GE reveal ® type incandescent and halogen lamps.
  • the light emitted from the coil or coils is similar to that of a blackbody spectrum, typically with a correlated color temperature (CCT) between about 2700 K and about 3200 K. This CCT range may be referred to as warm white.
  • CCT correlated color temperature
  • the Nd- doped glass dome 504 may function to filter out light in the yellow portion of the color spectrum, such that the light transmitted through the glass dome 504 of the light source 500 has an enhanced color preference, or color saturation, or color contrast capability that is typically preferred by a human observer relative to light emitted from the same light source without the Nd glass filter.
  • the blackbody is likewise assigned the reference value of 100 for the LPI metric.
  • LPI a value of 99.8 is considered to be a neutral value, not a maximum value.
  • the CRI metric quantifies the degree to which a light source renders eight pastel test colors exactly the same as the blackbody reference, and so it is a color“fidelity” metric of limited scope in color space.
  • the differences between the two SPDs is due entirely to the absorption of light by the Nd-doped glass, most of which occurs in the yellow range from about 570 nm to about 610 nm, and a weaker absorption in the green range from about 510 nm to about 540 nm.
  • the color preference benefits accrued from the Nd absorption are due to the yellow absorption.
  • An SPD may be plotted with an absolute scale of light intensity, e.g. with dimensions of Watts/nm or Watts/nm/cm 2 or other radiometric quantity, or it may be plotted in relative units, sometimes normalized to the peak intensity, as is provided here.
  • the SPD plot 600 of the incandescent lamp shown in FIG. 6a shows it to be an exceptionally well-balanced light source because there are no significant spikes or holes at any wavelengths.
  • Such a smooth curve that matches closely to the blackbody curve having the same CCT indicates outstanding color fidelity abilities.
  • the incandescent lamp typically has a CRI of about 99.
  • the Nd-incandescent lamp typically has a CRI of about 80. In spite of the lower CRI, most observers prefer the color rendering of the Nd-incandescent lamp over the incandescent lamp, especially for applications where organic objects are being illuminated, e.g. people, food, wood, fabrics, and the like.
  • FIG. 7a illustrates a reveal ® type LED light source 700 that includes one or more LEDs (FIG. 7b), and FIG. 7b is an exploded view of the light source 700 of FIG. 7a.
  • An LED (light-emitting diode) is an example of a solid state lighting (SSL) component, which may include semiconductor LEDs, organic LEDs, or polymer LEDs as sources of illumination instead of light sources such as incandescent bulbs that use electric filaments; or fluorescent tubes or high-intensity discharge tubes that use plasma and/or gas.
  • SSL solid state lighting
  • a light engine 712 comprising LEDs 706 and 708 and a printed circuit board 710 to which the LEDs are mounted, and which is attachable to a housing 704, so that, when assembled, the LEDs 706 and 708 are positioned within a glass dome 702 that is impregnated with neodymium oxide (Nd 2 O 3 ), such that most or all of the light emitted by the LEDs 706 and 708 passes through the dome 702.
  • Nd 2 O 3 neodymium oxide
  • housing 704 may be of different size and/or shape, and the solid state lighting components 706 and 708 may be connected directly and/or indirectly thereto during assembly.
  • the light emitted from the LEDs may be comprised of a mixture of light from a blue LED 802, having peak wavelength in the range of about 400 to about 460 nm (e.g., royal blue InGaN), and yellow-green light 804 having peak emission in the range of about 500 to about 600 nm created by the excitation of a phosphor material (such as a YAG:Ce phosphor) by the blue emission from the LED, and possibly also red light 806 having peak emission in the range of about 600 to about 670 nm created by the excitation of another phosphor (such as nitride or sulfide phosphor) by the blue emission from the LED.
  • a blue LED 802 having peak wavelength in the range of about 400 to about 460 nm (e.g., royal blue InGaN)
  • yellow-green light 804 having peak emission in the range of about 500 to about 600 nm created by the excitation of a phosphor material (such as a YAG:Ce
  • the mixed-light spectrum is also similar to that of a blackbody spectrum, but may include a depression in the wavelength range between the blue LED emission and the yellow-green phosphor emission.
  • the light source may have a correlated color temperature (CCT) between about 2700 K and about 3200 K (warm white), or it may have a higher CCT, as high as about 10,000 K or higher, or a lower CCT, as low as about 1800 K or lower.
  • CCT correlated color temperature
  • the Nd glass functions to filter out light in the yellow portion 808 of the color spectrum which may have been produced by the yellow-green and red phosphors, such that the light 810 (the entire solid line plot) emitting from the glass dome of the light source 700 has an enhanced color preference, or color saturation or color contrast capability, or whiteness that is typically preferred by a human observer relative to light 800 emitted from the same light source without the Nd glass filter.
  • Some conventional lamp types which include one or more low-pressure mercury (Hg) discharge lamps and special formulations of visible-light emitting phosphors (i.e., fluorescent (FL) or compact fluorescent (CFL) light sources) selected to reduce the amount of yellow light emitted by the light source are also known to enhance the color preference relative to their typical counterpart FL or CFL light source lamps without the special phosphor formulations.
  • FIG. 9 illustrates a reveal ® type CFL light source 900 that includes a low-pressure Hg discharge tube 902 coated with a customized mix of phosphors 904 having relatively low emission in the yellow spectrum.
  • the light source may also have a correlated color temperature (CCT) between about 2700 K and about 3200 K (warm white).
  • CCT correlated color temperature
  • the light source may have a higher CCT (e.g., as high as about 10,000 K or higher), or a lower CCT (e.g., as low as about 1800 K or lower).
  • the mixed light spectrum plot 1000 of the light source 900 having a relatively low emission in the yellow portion of the spectrum may have an enhanced color preference, or color saturation, or color contrast capability that is typically preferred by a human observer relative to light emitted from the same light source having a traditional phosphor mix.
  • Some additional conventional lamp types include one or more LEDs having green and red phosphors having peak wavelengths separated sufficiently to produce a depression in the yellow wavelength range and are used, for example, in grocery applications to enhance the colors of meats, vegetables, and produce (e.g. fruit).
  • the light emitted from the LEDs may be comprised of a mixture of light from blue light emission 1102, having peak wavelength in the range of about 400 nm to about 460 nm created by emission from a blue LED, and green light emission 1104 having peak wavelength in the range of about 500 nm to about 580 nm and FWHM 1108 of about 80 nm created by the excitation of a green phosphor by the blue emission from the LED, and red light emission 1106 having peak emission in the range of about 600 nm to about 670 nm and FWHM 1110 of about 100 nm created by the excitation of a red phosphor by the blue emission from the LED.
  • the mixed-light spectrum may have a depression in the wavelength range between the blue LED emission 1102 and the green phosphor emission 1104, and may include a second depression in the yellow wavelength range between the green phosphor emission 1104 and the red phosphor emission 1106.
  • the light source may also have a CCT between about 2700 K and about 6000 K, or it may have a higher CCT, e.g., as high as about 10,000 K or higher, or a lower CCT, e.g., as low as about 1800 K or lower.
  • the reduced emission in the yellow portion of the SPD plot 1100 resulting from the separation of the peak of the green phosphor emission 1104 at 528 nm and the peak of the red phosphor emission 1106 at 645 nm provides a light source spectrum plot 1100, resulting in an LPI of about 124.
  • each spectrum is comprised of three components (nominally blue, green, and red) superimposed into a composite spectrum.
  • the blue emission component 1302 is that of a blue LED, peak emission at about 450 nm, and having FWHM 1304 of about 15 nm. This wavelength was chosen to be representative of the typical blue LED presently used in most white light sources.
  • Other suitable blue emission components may be used, having characteristics, such as peak wavelengths in the range of about 400 nm to about 460 nm, and having FWHM ⁇ about 50 nm.
  • the LPI color metric is relatively much less sensitive to the blue emission than to the green and red emission. This can be understood from FIG.
  • the results of this DoE may be expected to represent the results given by any blue light source having peak wavelength in the blue or violet range (e.g. about 400 to about 460 nm) and having any FWHM less than about 50 nm.
  • the green component may be modelled using a family of five different green silicate phosphor emissions (FIG. 14), having a range of peak wavelengths from about 507 nm to about 533 nm representing the usual range of
  • silicate phosphors Commercially available, or easily manufactured silicate phosphors. This selection of silicate phosphors, as shown in FIG. 14, is based on a set of commercially available phosphors from Intematix Corporation and Nichia Corporation. Other suitable silicate phosphors may be used. Furthermore, the emission spectrum of the green component is allowed to vary by +5 nm, -5 nm, +10 nm, and -10 nm from the actual emission spectrum of each of the five commercially available phosphors in order to find trends that enable further optimization of the LPI response.
  • silicate 1 the shortest wavelength silicate phosphor
  • the full-width-at-half- maximum (FWHM), e.g. 1404, of each of the shifted green components is held constant, equal to that of the corresponding un-shifted commercially available phosphor, e.g.
  • a green silicate phosphor may include the family of phosphors containing a silicate-based fluorescent material activated by Eu 2+ having the general formula A 2 Si 1 -n O 4-2n :Eu 2+
  • -0.2 ⁇ n ⁇ 0.2 and A is at least one element selected from the group consisting of Sr, Ca, Ba, Mg, Zn, and Cd.
  • the red component may be modelled using a family of four different BR nitride phosphor emissions (FIG. 15) and a NR phosphor emission (FIG. 16).
  • the BR nitride phosphor is typically represented by general formula of CaAlSiN 3 :Eu 2+ .
  • These BR nitride phosphor materials absorb UV and blue light strongly and emit efficiently between about 600 nm and about 680 nm, e.g. 1502, with FWHM, e.g. 1504, of about 80 nm to about 120 nm, providing very strong emission in the deep red.
  • Many NR phosphors (FIG. 16) are known, and some of them are based on complex fluoride materials activated by Mn 4+ , such as those described in U.S. Pat. No. 7,358.542.
  • the Mn 4+ doped phosphors have the formula A x [MF y ]:Mn 4+ wherein A (alkali) is Li, Na, K, Rb, Cs, or a combination thereof; M (metal) is Si, Ge, Sn, Ti, Zr, AI, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MF y ] ion; y is 5, 6 or 7. These materials absorb blue light strongly and emit efficiently between about 610 nm and 660 nm, e.g.
  • the NR phosphor of this invention has a peak wavelength at about 631 nm, representing the commercially available PFS as described in U.S. Pat. No. 7,358.542; U.S. Pat. No. 7,497,973, and U.S. Pat. No. 7,648,649.
  • the NR phosphor comprised only a single, unique red component.
  • this particular NR phosphor may be substituted by another NR phosphor having similar peak wavelength to provide color preference benefits very similar to those provided by the NR phosphor.
  • the broad red component may be modelled using a family of four different BR nitride phosphor emissions, having a range of peak wavelengths from about 620 nm to about 670 nm, representing the usual range of commercially available, or easily manufactured broad red nitride phosphors. Therefore, in one or more embodiments, runs that included only a BR nitride phosphor, without a NR phosphor, the BR nitride phosphor included four different red components.
  • FIG. 15 displays the SPDs of the four un- shifted red components out of 20 red components that were used.
  • the DoE was divided into three groups, differentiated by the red phosphor: Group 1 comprising the NR PFS phosphor only (Silicate + PFS); Group 2 comprising each of the 20 BR nitride phosphors separately (Silicate + Nit) representing the commercially available red nitride phosphors; Group 3 comprising 3 ratios of BR power to NR power (emitted power summed over the full wavelength range of red emission, as provided in FIG. 15 and FIG. 16), in increments of 25%, so that (BR
  • n 0.25, 0.50, 0.75 for each of the 20 BR nitride phosphors in combination with the single NR phosphor (Silicate + PFS + Nit).
  • Group 3a 0.25
  • Group 3b 0.50
  • the division of the DoE into 3 groups is a matter of convenience for communicating the results.
  • a mixture of red nitride and PFS emitters may be used in one or more embodiments due to trade-offs in colorimetric and photometric capabilities of illuminants having NR vs. BR emitters, whereby the NR emitter may enhance efficacy by reducing the amount of radiation at wavelengths in the far tail of the photopic eye response curve, whereas the BR emitter may enhance color rendering or color preference, at the expense of efficacy.
  • LPI Lighting Preference Index
  • FIGS. 17-21 serve to define each of the 23 green and 20 BR phosphors in the DoE by its dominant wavelength.
  • the peak wavelength of a light source is that wavelength at which the emitted intensity is a maximum
  • the dominant wavelength is that wavelength of pure monochromatic light that most closely matches the hue (perceived color) of the light source.
  • the dominant wavelength of a light source is formally defined (see Wyszecki and Stiles, Color Science: Concepts and Methods,
  • FIG. 17c is the same as FIG. 17b, but showing the four commercially available BR nitride phosphors 1728 used in the DoE (as in FIG. 15), instead of the single NR phosphor.
  • FIG. 18a the color points 1834 of the 23 green phosphors used in the DoE are shown in a zoomed-in view of the 1931 CIE color space 1800: five commercially available green silicate phosphors, along with a modification of each of the five commercially available green silicate phosphors, where the emission spectrum is shifted by +10 nm, +5 nm, -5 nm, and–10 nm, as appropriate, representing a systematically parameterized, broad range of different green silicate phosphors.
  • the color points 1844 of 10 commercially available green silicate phosphors representing essentially the full range of green silicate phosphors that are presently commercially available, are shown in a zoomed-in view of the 1931 CIE color space 1800, along with the 23 green silicate phosphors 1834 of FIG. 18a that were used in the DoE. It is apparent from comparison of the color points of the group of 23 systematically parameterized green phosphors used in the DoE with the 10 commercially available green silicate phosphors, that the range of green silicate phosphors that are presently commercially available is fully represented in the DoE.
  • FIG. 19a the color points 1938 of the 20 BR phosphors used in the DoE are shown in a zoomed-in view of the 1931 CIE color space 1900: 4 commercially available broad red nitride phosphors, along with a modification of each of the four commercially available broad red nitride phosphors, where the emission spectrum is shifted by +10 nm, +5 nm, -5 nm, and–10 nm, representing a systematically parameterized, broad range of different BR phosphors.
  • 4 commercially available broad red nitride phosphors, along with a modification of each of the four commercially available broad red nitride phosphors, where the emission spectrum is shifted by +10 nm, +5 nm, -5 nm, and–10 nm, representing a systematically parameterized, broad range of different BR phosphors.
  • the color points 1948 of 14 commercially available broad red nitride phosphors representing essentially the full range of broad red nitride phosphors that are presently commercially available, are included along with the 20 BR phosphors 1938 of FIG. 19a that were used in the DoE. It is apparent from comparison of the color points of the group of 20 systematically parameterized BR phosphors used in the DoE with the 14 commercially available broad red nitride phosphors indicate that the range of broad red nitride phosphors that are presently commercially available is fully represented in the DoE.
  • the peak wavelength of a light source is that wavelength at which the emitted intensity is a maximum
  • the dominant wavelength is that wavelength of pure monochromatic light that most closely matches the hue (perceived color) of the light source
  • FIG. 20 shows the relationship between dominant and peak wavelengths for the 23 green phosphors used in the DoE.
  • the dominant wavelength is generally longer than the peak wavelength for each of the green phosphors. This may be primarily due to the asymmetry of the phosphor emission, as seen in FIG.
  • FIG. 21 shows the relationship between dominant and peak wavelengths for the 20 BR phosphors used in the DoE. As shown herein, the dominant wavelength is generally shorter than the peak wavelength for each of the BR phosphors. This may be primarily due to the extremely long wavelengths of the phosphor emission to the right of each peak wavelength as seen in FIG. 15, where the long-wavelength tails extend far beyond the wavelengths of the eye response (FIG.
  • each of the embodiments herein may be described as having a blue light source, a green silicate phosphor, a narrow red down-converter and/or a broad red down- converter, it is noted that at least one blue light source may be used, at least one green silicate phosphor may be used, at least one narrow red down-converter may be used, and/or at least one broad red down-converter may be used.
  • the colorimetric response of interest, LPI is plotted in FIG. 22a vs. Dom Sil (x-axis) and Duv (y-axis) of the color point at 2700 K.
  • LPI is plotted in FIG. 22b vs. Dom Sil and Duv of the color point at 3000 K.
  • the dominant wavelength of the green silicate phosphor may be in a range of 515 nm to about 563 nm.
  • the Dom Sil and Duv values of the 230 unique SPDs used in the Group 1 DoE are shown as groups of 23 different Dom Sil at each of 5 different Duv, superimposed on the background of the shading of the LPI iso-contours. Other suitable Duv levels may be used. Similar contour plots can be presented for a continuum of Duv levels within the range of Duv presented herein, with similar trends being realized. The smooth curves for LPI shown in FIGS.
  • LPI f(CCT, Duv, Dom Sil ), including polynomial terms as high as quartic, and all resultant variable interactions, providing a transfer function having Adjusted R 2 > 0.98.
  • LPI f(CCT, Duv, Dom Sil )
  • the particular SPD 2400 in the Group 1 DoE (Silicate + PFS) having the highest LPI value of about 144, corresponding to Dom Sil of about 550 nm, and Duv at about - 0.010, with CCT 2700 K, is illustrated in FIG. 24, showing the peak wavelength of the blue LED 2402 at about 450 nm, the peak wavelength of the green silicate phosphor 2404 at about 532 nm, the peak wavelength of the NR PFS phosphor 2406 at about 631 nm; and is compared with the SPD 604 of a reveal® incandescent lamp and with the SPD 602 of a blackbody emitter, each having similar CCT.
  • LPI increases as Dom Sil approaches the range from about 550 nm to about 557 nm, at a given Duv, which may be primarily due to the separation in wavelength between the green emitter and the narrow red emitter.
  • separation between the green and red emitters may be preferred, diminishing the typically large emission in the yellow, or even creating a depression in the yellow portion of the spectrum (e.g. about 570 to about 600 nm) which enhances the perceived saturation of red-green opponent colors, and blue-yellow opponent colors.
  • the separation between the green and red emitters is too large, oversaturation and hue distortion may arise, leading to a less preferred light source.
  • the LPI is maximized with a Dom Sil value of about 557 nm, while for color points near the white-body line (Duv of about -0.010), the LPI is maximized with a Dom Sil value of about 553 nm.
  • LPI tends toward a maximum value at Duv about -0.010; and that LPI tends toward a maximum value at Dom Sil values in the range of about 550 nm to about 557 nm, for this set of commercially available emitters (blue LED, green silicate phosphor, and NR phosphor) suggest that the LPI contours might be approximated by a simple shape defined only by the terms Duv to prescribe Whiteness, and Dom Sil as a surrogate for Color Appearance.
  • a simple quadrilateral may be defined by four points centered about a Duv of -0.010 to approximate the iso-contour for a given LPI value.
  • the quadrilaterals provide agreement with the LPI contours calculated from the DoE for every contour in FIGS. 22a,b having LPI of 120 or higher.
  • Each quadrilateral is comprised of four vertices, defining a region within the Dom Sil and Duv space.
  • Each vertex (v i ) describes a coordinate of (Dom Sil , Duv) and takes the general form of
  • the dashed-line approximations deviate from the respective exact LPI contours by an amount not exceeding about 2 or 3 points in LPI at any location, on any LPI contour, having a value of 120 or higher.
  • the Group 2 DoE (Silicate + Nit) comprised all combinations of 1 blue LED, 23 green silicate phosphors, and 20 BR Nitride phosphors, resulting in 460 unique
  • the colorimetric response of interest, LPI is plotted in FIG. 27a vs.
  • Dom Sil x-axis
  • Duv y-axis
  • the range of Peak Nit that were used in the Group 2 DoE is shown in FIG. 21 to be from about 610 nm to about 680 nm, including 20 different BR phosphors in that range.
  • the Dom Sil and Duv values of the 230 unique combinations of 23 different Dom Sil values at each of five different Duv values, and two different color temperatures, as shown in FIG. 23 and used in the Group 1 DoE are the same 230 unique combinations of Dom Sil and Duv that were used in the Group 2 DoE in combination with each of the 20 different BR phosphors.
  • the fine spacing between Dom Sil values on the x-axis and the Duv values on the y-axis of the 230 unique SPDs used in the Group 1 DoE have been found to provide smooth interpolations between discrete SPDs actually used in the DoE.
  • the five Duv levels were chosen to illustrate the effect of color point, or Duv, on LPI. Other suitable Duv levels may be used.
  • similar contour plots may be presented for a continuum of Duv levels within the range of Duv presented herein, with similar trends being realized.
  • the SPD having the highest LPI (about 144) among the 2300 SPDs at 2700 K in the Group 2 DoE is shown in FIG. 29.
  • the particular SPD 2900 in the Group 2 DoE (Silicate + Nit) having the highest LPI value of about 144, corresponding to Dom Sil of about 550 nm, and Duv at about -0.010, with CCT 2700 K, is illustrated in FIG.
  • LPI increases with increasing Peak Nit
  • the Dom Sil wavelength for maximum LPI also increases with increasing Peak Nit , at a given Duv, which may be primarily due to the separation in wavelength between the green emitter and the BR emitter.
  • separation between the green and red emitters may be preferred, diminishing the typically large emission in the yellow, or even creating a depression in the yellow portion of the spectrum (e.g. about 570 to about 600 nm) which enhances the perceived saturation of red-green opponent colors, and blue-yellow opponent colors.
  • the separation between the green and red emitters is too large, oversaturation and hue distortion may arise, leading to a less preferred light source.
  • the LPI may be maximized with a Dom Sil value in the range of about 554 nm to about 563 nm.
  • the LPI may be maximized with a Dom Sil value in the range of about 548 nm to about 560 nm.
  • the Group 3 DoE (Silicate + PFS + Nit) included all combinations of the 1 blue LED, 23 green silicate phosphors, and 20 BR Nitride phosphors, described above, resulting in 460 unique combinations of emitters (1 B x 23 G x 1 NR x 20 BR) at each of 3 different ratios of BR power to NR power (emitted power summed over the full wavelength range of red emission, as provided in FIG. 15 and FIG.
  • the range of Peak Nit used in the Group 3 DoE, as shown in FIG. 21, is from about 610 nm to about 680 nm, including 20 different BR phosphors in that range.
  • the SPD having the highest LPI (about 144) among the 2300 SPDs at 2700 K in the Group 3a DoE is shown in FIG. 32.
  • the SPD having the highest LPI (about 144) among the 2300 SPDs at 2700 K in the Group 3b DoE is shown in FIG. 35.
  • the SPD having the highest LPI (about 144) among the 2300 SPDs at 2700 K in the Group 3c DoE is shown in FIG. 38.
  • the Dom Sil and Duv values of the 230 unique combinations of 23 different Dom Sil values at each of five different Duv values, and two different color temperatures, as shown in FIG. 23 and used in the Group 1 DoE and Group 2 DoE are the same 230 unique combinations of Dom Sil and Duv that were used in the Group 3 DoE, in combination with each of the 20 different BR phosphors.
  • the fine spacing between Dom Sil values on the x-axis and the Duv values on the y-axis of the 230 unique SPDs used in the Group 3 DoE have been found to provide smooth interpolations between discrete SPDs actually used in the DoE. While five Duv levels were used herein to illustrate the effect of color point, or Duv, on LPI, other suitable Duv levels may be used.
  • LPI increases with increasing Peak Nit
  • the Dom Sil wavelength for maximum LPI also increases with increasing Peak Nit , at a given Duv and n, which may be primarily due to the separation in wavelength between the green emitter and the red emitters.
  • separation between the green and red emitters may be preferred, diminishing the typically large emission in the yellow, or even creating a depression in the yellow portion of the spectrum (e.g. about 570 to about 600 nm) which enhances the perceived saturation of red-green opponent colors, and blue-yellow opponent colors.
  • the separation between the green and red emitters is too large, oversaturation and hue distortion may arise, leading to a less preferred light source.
  • the LPI may be maximized with a Dom Sil value in the range of about 551 nm to about 563 nm.
  • the LPI may be maximized with a Dom Sil value in the range of about 548 nm to about 560 nm.
  • the LED light source may include one or more groups of LEDs that may each consist of one or more blue LEDs coated with green silicate phosphor and a NR phosphor. This is termed the "Silicate + PFS" composite light source.
  • the portion of the blue light generated by the blue LED that is not absorbed by the phosphor materials, combined with the light emitted by the phosphor materials may provide light which appears to the human eye as being nearly white in color.
  • the spectrum of a Silicate + PFS light source having enhanced color preference may be composed of a blue LED peak emission in the range of about 400 nm to about 460 nm, a green peak emission in the range of about 506 nm to about 543 nm created by the excitation of a silicate phosphor by the blue emission from the LED, and a red peak emission at about 631 nm created by the excitation of a NR phosphor by the blue emission from the LED, as depicted in FIG.24.
  • the spectrum may differ from that of a blackbody in that it may include a depression in the wavelength range between the blue LED emission and the green silicate phosphor emission, and may include a depression in the yellow wavelength range between the green silicate phosphor emission and the NR phosphor emission.
  • the light source in this first exemplary embodiment may have a CCT between about 2700 K and about 3200 K. In one or more embodiments, the light source may have a higher CCT (e.g., as high as about 10,000 K or higher), or a lower CCT (e.g., as low as about 1800 K or lower).
  • the reduced emission in the yellow portion of the color spectrum may result from the separation of the peaks of the green silicate phosphor and the NR phosphor and may be created by the relatively narrow width and relatively long peak wavelength of the NR PFS phosphor.
  • the reduced emission may be further enhanced in the yellow portion of the color spectrum by a relatively short peak wavelength of the green silicate phosphor, compared with other typical green or yellow-green phosphors (i.e. garnet phosphors such as YAG).
  • the depression of the spectrum in the yellow portion, if sufficiently deep, and the enhanced emission in the red and green relative to a blackbody emitter, may provide a light source having an enhanced color preference, or color saturation, or color contrast capability that is typically preferred by a human observer relative to light emitted from the same light source employing a typical blue and green and red phosphor combinations that do not produce a sufficiently deep depression in the yellow portion.
  • the curve 2400 is the particular SPD that provided the maximum LPI of 144 from among the 230
  • the corresponding SPD at 3000 K would appear very similar, with similar CRI and LPI values.
  • an LPI of about 144 is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + PFS spectrum 2400 than is possible by using light sources typically having LPI of 120 or less.
  • the peak and dominant wavelengths of the green silicate phosphor 2404 in FIG. 24 are shifted slightly relative to the optimal peak and dominant wavelengths of 532 nm and 550 nm of the first embodiment.
  • an LPI of about 135 or greater is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + PFS spectrum 2400 than is possible by using light sources typically having LPI of 120 or less, and only very slightly less so than the first embodiment having LPI of about 144.
  • an LPI of about 120 or greater is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a more preferred color appearance when utilizing the Silicate + PFS spectrum 2400 than is possible by using light sources typically having LPI of 120 or less, although noticeably less so than the first embodiment having LPI of about 144.
  • the LED light source may include one or more groups of LEDs that may each consist of one or more blue LEDs coated with green silicate phosphor and a BR nitride phosphor (Silicate + Nit), where the portion of the blue light generated by the blue LED that is not absorbed by the phosphor materials, combined with the light emitted by the phosphor materials provides light which appears to the human eye as being nearly white in color.
  • groups of LEDs may each consist of one or more blue LEDs coated with green silicate phosphor and a BR nitride phosphor (Silicate + Nit), where the portion of the blue light generated by the blue LED that is not absorbed by the phosphor materials, combined with the light emitted by the phosphor materials provides light which appears to the human eye as being nearly white in color.
  • the spectrum of a Silicate + Nit light source having enhanced color preference may be composed of a blue LED peak emission in the range of about 400 nm to about 460 nm, a green peak emission in the range of about 506 nm to about 543 nm created by the excitation of a silicate phosphor by the blue emission from the LED, and a red peak emission in the range of about 610 nm to about 680 nm created by the excitation of a BR nitride phosphor by the blue emission from the LED, as depicted in FIG. 29.
  • the spectrum may differ from that of a blackbody in that it may include a depression in the wavelength range between the blue LED emission and the green silicate phosphor emission, and it may include a depression in the yellow wavelength range between the green silicate phosphor emission and the BR phosphor emission.
  • the light source may have a CCT between about 2700 K and about 3200 K. In one or more embodiments the light source may have a higher CCT (e.g., as high as about 10,000 K or higher), or a lower CCT (e.g., as low as about 1800 K or lower).
  • the reduced emission in the yellow portion of the color spectrum may result from the separation of the peaks of the green silicate phosphor and the BR phosphor that may be created primarily by the relatively long peak wavelength of the BR nitride phosphor.
  • the reduced emission in the yellow portion of the color spectrum may be further enhanced by a relatively short peak wavelength of the green silicate phosphor, compared with other typical green or yellow-green phosphor s (i.e. garnet phosphors such as YAG).
  • the depression of the spectrum in the yellow, if sufficiently deep, and the enhanced emission in the red and green relative to a blackbody emitter, may provide a light source having an enhanced color preference, or color saturation, or color contrast capability that may be preferred by a human observer relative to light emitted from the same light source employing a typical blue and green and red phosphor combinations that do not produce a sufficiently deep depression in the yellow.
  • the plot 2900 is the particular SPD that provided the maximum LPI of 144 from among the 4600 combinations of SPDs in Group 2 (Silicate + Nit) of the DoE.
  • the LPI score of 144 is very high (in one or more embodiments, the maximum possible LPI may be about 150), meaning that a human observer will perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + PFS spectrum 2900 than is possible by using light sources typically having LPI of 120 or less.
  • an LPI of about 144 is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + Nit spectrum 2900 than is possible by using light sources typically having LPI of 120 or less.
  • a fifth exemplary embodiment of a light source providing slightly reduced color preference (LPI) for a Silicate + Nit light source than the fourth embodiment
  • the peak and dominant wavelengths of the green silicate phosphor 2904 in FIG. 29 are shifted relative to the optimal peak and dominant wavelengths of 532 nm and 550 nm of the fourth embodiment
  • the peak wavelength of the nitride red phosphor 2906 in FIG. 29 is shifted relative to the optimal peak wavelength of 660 nm of the fourth embodiment.
  • Dom Sil may be in the range of about 530 nm to about 563 nm, and Peak Nit may be in the range of about 640 to about 680 nm, while Duv of the color point remains near - 0.010 (between about -0.006 and about -0.014), with CCT of about 2700 K to about 3000 K.
  • an LPI of about 135 or greater is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + Nit spectrum 2900 than is possible by using light sources typically having LPI of 120 or less, and only very slightly less so than the fourth embodiment having LPI of about 144.
  • a sixth exemplary embodiment of a light source providing further reduced color preference (LPI) for a Silicate + Nit light source than the fourth or fifth embodiments, but still exceeding that of the prior art, the peak and dominant wavelengths of the green silicate phosphor 2904 in FIG. 29 are shifted relative to the optimal peak and dominant wavelengths of 532 nm and 550 nm of the fourth embodiment, and the peak wavelength of the nitride red phosphor 2906 in FIG. 29 is shifted even more relative to the optimal peak wavelength of 660 nm of the fourth embodiment.
  • LPI color preference
  • Dom Sil may be in the range of about 515 nm to about 563 nm
  • Peak Nit may be in the range of about 620 nm to about 680 nm
  • Duv of the color point is ideally near -0.010, but may be anywhere in the range of about 0.000 to about -0.020, with CCT of about 2700 K to about 3000 K.
  • an LPI of about 120 or greater is obtained, meaning that a human observer will perceive more saturated colors, enhanced whiteness, and a more preferred color appearance when utilizing the Silicate + Nit spectrum 2900 than is possible by using light sources typically having LPI of 120 or less .
  • the LED light source may include one or more groups of LEDs that may each consist of one or more blue LEDs coated with green silicate phosphor and a combination of NR PFS phosphor and BR nitride phosphor (Silicate + PFS + Nit), where the portion of the blue light generated by the blue LED that is not absorbed by the phosphor materials, combined with the light emitted by the phosphor materials, may provide light which appears to the human eye as being nearly white in color.
  • the spectrum of a Silicate + PFS + Nit light source having enhanced color preference may be composed of a blue LED peak emission in the range of about 400 nm to about 460 nm, a green peak emission in the range of about 506 nm to about 543 nm created by the excitation of a silicate phosphor by the blue emission from the LED, a red peak emission at about 631 nm created by the excitation of a NR PFS phosphor by the blue emission from the blue LED, and additional red emission having a peak in the range of about 610 nm to about 680 nm created by the excitation of a BR nitride phosphor by the blue emission from the blue LED, as depicted in FIGS. 32, 35, and 38.
  • the spectrum shown in FIGS. 32, 35 and 38 may differ from that of a blackbody spectrum in that it may include a depression in the wavelength range between the blue LED emission and the green silicate phosphor emission, and it may include a depression in the yellow wavelength range between the green silicate phosphor emission and the red phosphor emissions.
  • the light source of this seventh embodiment may have a CCT between about 2700 K and about 3200 K. In one or more embodiments, the light source may have a higher CCT (e.g., as high as about 10,000 K or higher), or a lower CCT (e.g., as low as about 1800 K or lower).
  • the reduced emission in the yellow portion of the color spectrum may result from the separation of the peaks of the green silicate phosphor and the red phosphors that may be created by the relatively narrow width and relatively long peak wavelength of the NR PFS phosphor and the relatively long peak wavelength of the BR nitride phosphor.
  • the reduced emission in the yellow portion may be further enhanced by a relatively short peak wavelength of the green silicate phosphor, compared with other typical green or yellow-green phosphors (i.e. garnet phosphors such as YAG).
  • the depression of the spectrum in the yellow portion, if sufficiently deep, and the enhanced emission in the red and green portions relative to a blackbody emitter, may provide a light source having an enhanced color preference, or color saturation, or color contrast capability that may be typically preferred by a human observer relative to light emitted from the same light source employing typical blue and green and red phosphor combinations that do not produce a sufficiently deep depression in the yellow.
  • the curves 3200, 3500, and 3800 are the particular SPDs that provided the maximum LPI of 144 for all three n values (0.25, 0.50, and 0.75), from among the 4600 combinations of SPDs in each of Groups 3a, 3b, and 3c of the DoE.
  • the peak wavelength of the blue LEDs 3202, 3502, and 3802 occurs at about 450 nm
  • the peak and calculated dominant wavelengths of the green silicate phosphor 3204, 3504, and 3804 occur at about 532 nm and 550 nm respectively
  • the peak wavelength of the NR phosphor 3206, 3506, and 3806 occurs at about 631 nm
  • the corresponding SPD at 3000 K may appear very similar, with similar CRI and LPI values.
  • LPI scores of 144 for all three n values (0.25, 0.50, and 0.75) are high (in one or more embodiments, the maximum possible LPI may be about 150), so that a human observer may perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + PFS + Nit spectra 3200, 3500, and 3800 than is possible by using light sources typically having LPI of 120 or less.
  • an LPI of about 144 is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + PFS + Nit spectra 3200, 3500, and 3800 than is possible by using light sources typically having LPI of 120.
  • the peak and dominant wavelengths of the green silicate phosphor 3204, 3504, and 3804 in FIGS. 32, 35 and 38 are shifted relative to the optimal peak and dominant wavelengths of the seventh embodiment, and the peak wavelengths of the nitride red phosphor 3208, 3508, and 3808 in FIGS. 32, 35 and 38 are shifted relative to the optimal peak wavelength of 660 nm of the seventh embodiment.
  • Dom Sil may be in the range of about 530 nm to about 563 nm
  • Peak Nit may be in the range of about 610 nm to about 680 nm while Duv of the color point remains near -0.010 (between about -0.006 and about -0.014), with CCT of about 2700 K to about 3000 K.
  • an LPI of about 135 or greater is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a much more preferred color appearance when utilizing the Silicate + PFS + Nit spectra 3200, 3500, and 3800 than is possible by using light sources typically having LPI of 120 or less, and only very slightly less so than the seventh embodiment having LPI of about 144.
  • a ninth exemplary embodiment of a light source providing further reduced color preference (LPI) for a Silicate + PFS + Nit light source than the seventh embodiment, but still exceeding that of light sources typically having LPI of 120 or greater, the peak and calculated dominant wavelengths of the green silicate phosphor 3204, 3504, and 3804 in FIGS. 32, 35 and 38 are shifted relative to the optimal peak and dominant wavelengths of the seventh embodiment, and the peak wavelength of the nitride red phosphor 3208, 3508, and 3808 in FIGS. 32, 35 and 38 is shifted relative to the optimal peak wavelength of 660 nm of the seventh embodiment.
  • LPI color preference
  • Dom Sil may be in the range of about 515 nm to about 563 nm
  • Peak Nit may be in the range of about 610 nm to about 680 nm
  • Duv of the color point is ideally near -0.010, but may be anywhere in the range of about 0.000 to about -0.020, with CCT of about 2700 K to about 3000 K.
  • an LPI of about 120 or greater is obtained, so that a human observer may perceive more saturated colors, enhanced whiteness, and a more preferred color appearance when utilizing the Silicate + PFS + Nit spectra 3200, 3500, and 3800 than is possible by using light sources typically having LPI of 120 or less.
  • a yellow-absorbing filter such as neodymium (Nd) glass, or a Nd compound, or a comparable yellow filter
  • a yellow-absorbing filter such as neodymium (Nd) glass, or a Nd compound, or a comparable yellow filter
  • Nd neodymium
  • a neodymium (Nd) glass dome may be placed over the LED light engine, and the Nd glass dome may function to suppress yellow light to further enhance the perception of red and green vibrancy.
  • the peak wavelength of the red phosphor may be moved to shorter wavelengths or the FWHM of the red phosphor to be increased.
  • the inclusion of a yellow filter may provide further enhanced color preference (higher LPI) by further enhancing the depression in the yellow.
  • the composite light source 4000 may include a reflective chamber 4002, an LED (light emitting diode) 4004, at least one phosphor 4006 (“phosphor”), a transparent encapsulant 4008, and a transparent lens 4010.
  • the LED 4004 may include a blue emitter.
  • the phosphor 4006 may be a silicate or a blend of any of silicate, NR and BR phosphors, as described above in any of exemplary embodiments 1 -9. As shown in FIG.
  • the phosphor 4006 may be suspended in the transparent encapsulant 4008 that fills a reflector cup portion 4002 of the composite light source.
  • the phosphor 4006 covers the LED 4004, and the transparent encapsulant 4008 covers the phosphor 4006 and fills the reflector cup 4002.
  • a lens 4010 covers the LED 4004, and the transparent encapsulant 4008 fills the reflector cup 4002, while the phosphor 4006 is positioned on top of the transparent encapsulant 4008.
  • the composite light source may be represented in any other suitable form. For example, separate/multiple LEDs with different phosphors, remote phosphors (e.g., phosphor separated from the LED),

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Abstract

Selon certains modes de réalisation, une source lumineuse composite comprend au moins une source lumineuse bleue présentant une longueur d'onde de pic dans la plage d'environ 400 nanomètres (nm) à environ 460 nm ; au moins une substance fluorescente silicatée ; au moins un convertisseur-abaisseur dans le rouge étroit ; et la source lumineuse composite présentant un indice de préférence d'éclairage (LPT) d'au moins 120. L'invention concerne également de nombreux autres aspects.
PCT/US2015/025128 2014-09-09 2015-04-09 Sources lumineuses à del à préférence de couleur augmentée, utilisant du silicate, du nitrure et des substances fluorescentes à base de pfs Ceased WO2016039817A1 (fr)

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