Phosphor-converted red LED and color-tunable multi-LED packaged light-emitting device

Abstract

The lighting device (1350) comprises a package (1314) comprising a first LED (1310) generating light having a peak emission wavelength from 620 nm to 640 nm (red), a second LED (1354) having a peak emission wavelength from 500 nm to 565 nm (green), and a third LED (1359) generating white light having a CCT of at least 1800K, where the first LED (1310) is a phosphor-converted LED comprising an LED chip (1326) generating light having a dominant wavelength from 400 nm to 480 nm (violet to blue), and a narrowband red phosphor with a FWHM of less than 55 nm.

Description

[Technical field]

[0001] CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 299,408, filed January 13, 2022, entitled "Phosphor-Converted Red LEDs," which is incorporated herein by reference in its entirety.

[0002] FIELD OF THEINVENTION A first aspect of the present invention generally relates to phosphor-converted (PC) color LEDs (Light Emitting Diodes) that generate light of a selected color. More specifically, a preferred embodiment of the present invention relates to phosphor-converted red LEDs (PC red LEDs). Another aspect of the present invention relates to a color-tunable multi-LED (Light Emitting Diode) package light emitting device (multi-LED package) that can generate light having a color temperature from 2200K to 6500K, optionally from red to blue. More specifically, but not exclusively, the present invention relates to a color-tunable multi-LED package that utilizes PC red LEDs. [Background technology]

[0003] 2. Background of the Invention Phosphor-converted color LEDs (light-emitting diodes), also known as "PC color LEDs", generally comprise a blue LED chip and a phosphor (photoluminescent) material that converts substantially all of the excitation light generated by the LED chip into light of a selected color, such as green, yellow, orange, or red, through a process of photoluminescent wavelength conversion. Since all of the light generated by the LED chip is converted into light of a selected color, such PC color LEDs can also be referred to as fully phosphor-converted (FPC) color LEDs. PC color LEDs are contrasted with PC white LEDs, in which there is only partial conversion of the blue light generated by the LED chip, with the remaining blue light ultimately contributing to the emission generation of white light. The light generated by PC color LEDs is generally broadband and has a FWHM (Full Width at Half Maximum) of 70 nm to 120 nm depending on the phosphor composition. The color (peak emission wavelength) of the light generated by PC color LEDs depends on the composition of the phosphor material.

[0004] PC color LEDs are contrasted with direct-emitting "color LEDs," which directly emit nearly monochromatic light (FWHM ≒ 20-25 nm) without photoluminescence (phosphor) wavelength conversion, and the color of the light is determined by the semiconductor material system of the LED chip. For example, direct-emitting green LEDs use InGaN (indium gallium nitride) LED chips, direct-emitting red LEDs use AlInGaP (aluminum indium gallium phosphide) LED chips, and direct-emitting blue LEDs use InGaN (indium gallium nitride) LED chips.

[0005] Due to their narrowband emission characteristics, direct-emitting red, green, and blue color LEDs find particular utility for improving the color gamut of color-tunable multi-LED packages for displays and general lighting, for example in RGB (Red Green Blue) systems, such as display backlighting. Current color-tunable multi-LED packages generally include red, green, and blue direct-emitting "color LED" chips.

[0006] A known color-tunable multi-LED package (Surface Mount Device-SMD) is shown in Figures 1A and 1B, where Figure 1A shows a top view and Figure 1B shows a side cross-sectional view of the multi-LED package taken along line AA. The known multi-LED package 1 comprises a lead frame 2 for powering red, green and blue direct-emitting LED chips 3R, 3G, 3B. A housing 4 is molded on the lead frame and comprises a single cavity 5 (e.g., circular in shape). The red, green and blue direct-emitting LED chips 3R, 3G, 3B are mounted on the floor of the cavity 5 and electrically connected to the lead frame 2. To protect the LED chips 3 from the external environment, the cavity 5 is typically filled with a light-transmitting encapsulant such as a silicone material. Portions of the lead frame 2 extend laterally to the outer edges of the housing 4, and respective electrical terminals 7R, 7G, 7B, 8R, 8G, 8B are formed along opposing edges and the bottom of the package to allow independent (individual) powering of the anodes (positive poles) and cathodes (negative poles) of each of the red, green, and blue direct-emitting color LED chips 3R, 3G, 3B. A PC white LED package is to be contrasted with the direct-emitting color LED chips, and comprises a direct-emitting blue LED chip and a photoluminescent material, typically a phosphor material, which converts a portion of the blue excitation light generated by the LED chip, with the remaining blue light ultimately contributing to the white luminescent product. The phosphor material may be embedded in a light-transmitting encapsulant used to fill the cavity.

[0007] However, a drawback of multi-LED packages based on direct-emitting color LEDs is that, since they are based on different semiconductor material systems, each color LED chip has different characteristics, such as thermal stability, aging characteristics, driving requirements, etc. As a result of these different characteristics, the light output of red, green, and blue LEDs change differently from each other with temperature and time. The color composition of the light generated by RGB systems based on color LEDs consequently changes with temperature and time, and such LED systems may use complex driving circuits to compensate for these different characteristics, which may result in additional costs during manufacturing and maintenance. In contrast, PC color LEDs eliminate the need for such measures, since they are all based on LED chips with the same semiconductor materials and have the same driving requirements, thermal stability, etc.

[0008] Current PC red LEDs generally use broadband red nitride phosphors and have peak emission wavelengths between 620 nm and 630 nm. For many applications, including display backlighting, automotive brake lights and turn signals, traffic signals, emergency vehicle lights, etc., it would be desirable if PC red LEDs could generate narrowband red light with FWHM similar to or shorter than that of direct-emitting color LEDs (FWHM = 20-25 nm).

[0009] For example, K2SiF6:Mn 4+ (KSF), K2TiF6:Mn 4+ (KTF), and K2GeF 6: Mn 4+Narrow-band red phosphors, such as manganese-activated fluoride-based phosphors like (KGF), have a very narrow red emission spectrum (less than 10 nm full width at half maximum for their main emission line spectrum), which makes them highly desirable for achieving high brightness and luminous efficiency (about 25% brighter than broad-band red phosphors like europium-activated red nitride phosphor materials like CASN-CaAlSiN3:Eu) in PC white LEDs. Although narrow-band red fluoride phosphors at first glance seem to be an ideal choice for PC red LEDs, there are drawbacks that make their use in PC red LEDs challenging. For example, the absorption efficiency of narrow-band red fluoride phosphors is significantly lower (typically about 10 times lower) than that of red nitride phosphors currently used in PC red LEDs. Thus, achieving full conversion from blue light to red light requires the usage of narrow-band red fluoride phosphors that are 5 to 20 times greater than that of red nitride phosphors. Such an increase in the overall phosphor usage significantly increases the cost of manufacturing, and especially since narrow-band red fluoride phosphors are significantly more expensive (e.g., at least five times more expensive) than europium-activated red nitride phosphors, this makes narrow-band red fluoride phosphors prohibitively expensive for use in PC red LEDs.

[0010] Furthermore, the relatively very low absorption efficiency of narrow-band red fluoride phosphors can result in unconverted blue light generated by the LED chip and ultimately luminescently produced light, so-called "blue light pass". Unconverted blue light reduces the color purity of the red light emission. Although "blue light pass" may be acceptable in white light systems where blue light is a component of white light, such as backlighting for displays, for applications requiring "pure red" (nearly monochromatic) light, "blue light pass" reduces the color purity of the red light and is therefore highly undesirable.

[0011] Another problem with utilizing only narrowband red fluoride phosphors is that although narrowband red fluoride phosphors provide narrowband red emission, they react readily with water or moisture causing damage to the manganese dopant, resulting in degradation or loss of photoluminescence emission (i.e., quantum efficiency) of the phosphor. Additionally, the reaction of fluoride-based compounds with water can generate highly corrosive hydrofluoric acid that can react with LED packaging materials, such as bond wires, causing premature failure of the device. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention is intended to meet and / or overcome the above-mentioned limitations by presenting new designs and methods not previously contemplated or possible with known configurations. More specifically, preferred embodiments of the present invention relate to, but are not limited to, the following improvements: increasing the luminous efficiency of color-tunable multi-LED packages through a novel phosphor packaging structure that effectively improves the blue absorption efficiency of narrow-band red fluoride phosphors; increasing the color purity of PC red LEDs by reducing "blue light pass"; reducing the usage of narrow-band red fluoride phosphors; and isolating narrow-band red fluoride phosphors from water / moisture in the surrounding environment. [Means for solving the problem]

[0013] The first aspect of the present invention generally relates to a PC red LED based on an InGaN-based blue-emitting LED, which contains a combination of a narrow-band red fluoride phosphor (e.g., a manganese-activated fluoride narrow-band red phosphor) and a red phosphor with higher absorption efficiency, such as a broad-band red phosphor. The inclusion of a broad-band red phosphor with higher absorption efficiency than the narrow-band red fluoride phosphor converts the blue light not converted by the narrow-band red fluoride phosphor into red light, greatly reducing or even eliminating blue light passing and improving color purity. It can thus be said that the inclusion of a red phosphor with higher absorption efficiency than the narrow-band red fluoride phosphor compensates for the lower absorption efficiency of the narrow-band red fluoride phosphor.

[0014] The broadband red phosphor and the narrowband red fluoride phosphor can be provided in the same (single) layer, for example as a mixture, which can improve the ease with which the PC red LED can be manufactured, thus reducing the cost and time of manufacture.

[0015] In another embodiment, each of the broadband red phosphor and the narrowband red fluoride phosphor can be provided in a respective layer, and the layer containing the narrowband red fluoride phosphor is disposed closer to the LED chip than the layer containing the broadband red phosphor. Such an arrangement can effectively increase the absorption efficiency of the narrowband red fluoride phosphor and greatly reduce the usage of the narrowband red fluoride phosphor. The layer containing the narrowband red fluoride phosphor can be in direct contact with at least one of the light-emitting surfaces of the LED chip. The broadband red phosphor can be in direct contact with the layer containing the narrowband red fluoride phosphor and can completely cover (seal) this layer. Such a configuration / arrangement can provide environmental protection for the layer containing the narrowband red fluoride phosphor and can improve the reliability of the entire device.

[0016] According to one aspect of the present invention, a red light emitting device is provided, the red light emitting device comprising: an LED chip having a peak emission wavelength from 400 nm to 500 nm; and a photoluminescent material, the photoluminescent material including a narrowband red fluoride phosphor and a broadband red phosphor.

[0017] In a preferred embodiment, the narrowband red fluoride phosphor and the broadband red phosphor can be arranged as a single layer photoluminescent structure. The phosphors can be provided, for example, in the same layer. The phosphors can be provided in a single layer, typically as a mixture. As used herein, "direct contact" means without an air gap or photoluminescent containing layer. In another preferred embodiment, the device can include a light-transmitting passivation layer between the layer and the LED chip. The light-transmitting layer provides passivation for the LED chip, providing a barrier against possible effects of the narrowband red fluoride phosphor on the LED chip. Such an arrangement can improve the reliability of the device.

[0018] To further improve the absorption efficiency of the narrowband red fluoride phosphor, the narrowband red fluoride phosphor can be placed closer to the LED than the broadband red phosphor. By placing the narrowband red fluoride phosphor closer to the LED chip, the absorption efficiency of the narrowband red fluoride phosphor is effectively increased because the narrowband red fluoride phosphor does not have to compete with the broadband red phosphor for blue photons.

[0019] In a preferred embodiment, the red light emitting device may include a two-layer photoluminescent structure, the two-layer photoluminescent structure including a first layer containing a narrowband red fluoride phosphor disposed adjacent to the LED chip, and a second layer disposed on and covering the first layer containing a broadband red phosphor, the second layer being capable of partially or completely covering the first layer.

[0020] Compared to a single layer photoluminescent structure, a two-layer photoluminescent structure having a first layer containing only or substantially (at least 90% by weight) only narrow-band red fluoride phosphor covered by a second layer can provide numerous advantages, including, but not limited to: (1) a significant reduction in the amount of narrow-band red fluoride phosphor used (approximately 40% reduction); (2) the second layer provides environmental protection to the first layer, thereby reducing the opportunity for water / moisture to reach and degrade the narrow-band red fluoride phosphor; and (3) a significant reduction or even elimination of "blue light pass" resulting in better color purity of the red light generated by the device.

[0021] The first layer is in direct contact with at least one light emitting surface (surface) of the LED chip.

[0022] The second layer can be in direct contact with the first layer.

[0023] To further reduce the usage of narrowband red fluoride phosphor, the first layer can further comprise particles of a light scattering material, such as particles of zinc oxide; silicon dioxide; titanium dioxide, magnesium oxide; barium sulfate; aluminum oxide, and combinations thereof.

[0024] The narrow band red fluoride phosphor is K2SiF6:Mn 4+ , K2GeF6:Mn 4+ , and K2TiF6:Mn 4+ or K2SiF6:Mn 4+ , K2GeF6:Mn 4+ , and K2TiF6:Mn 4+ The signal may be selected from the group consisting of:

[0025] To reduce the FWHM of the red emission generated by the device, the peak emission wavelength of the broadband red phosphor can be selected to be approximately the same as the peak emission wavelength of the narrowband red fluoride phosphor. In a preferred embodiment, the peak emission wavelength of the broadband red phosphor can be within 5 nm of the peak emission wavelength of the narrowband red fluoride phosphor. The broadband red phosphor can have a peak emission wavelength of 620 nm to 640 nm and have the general composition AAlSiN3:Eu 3+ where A is at least one of Ca, Sr, or Ba.

[0026] In preferred embodiments, the red light emitting device generates red light having a color purity of at least 90% and a FWHM of less than 30 nm, a FWHM of less than 20 nm, or a FWHM of less than 10 nm.

[0027] According to another aspect of the present invention, a red light emitting device is contemplated, comprising: an LED flip chip having a peak emission wavelength of 400 nm to 500 nm; and a photoluminescent material in direct contact with at least one light emitting surface of the LED flip chip, the photoluminescent material including a narrowband red fluoride phosphor and a broadband red phosphor.

[0028] In a preferred embodiment, the narrowband red fluoride phosphor and the broadband red phosphor can be configured as a single layer photoluminescent structure. The phosphors can be contained in the same layer. The phosphors can be contained in a single layer, typically as a mixture, which can be in direct contact with at least one light-emitting surface of the LED flip chip.

[0029] In a preferred embodiment, the narrowband red fluoride phosphor and the broadband red phosphor can be configured as a two-layer photoluminescent structure. In one preferred embodiment, the red light emitting device includes a first layer and a second layer, the first layer containing the narrowband red fluoride phosphor adjacent to the LED chip, and the second layer is on the first layer and contains the broadband red phosphor material. The first layer can be in direct contact with at least one light emitting surface (surface) of the LED flip chip, and the second layer can be in direct contact with the first layer.

[0030] The phosphor-converted red LED (PC Red LED) according to an embodiment of the present invention finds utility as a red light source in a light emitting device (illumination device), such as an RGB (Red, Green, Blue) multi-LED package comprising a red LED, a green LED, and a blue LED, and the RGB light emitting device finds utility in a color tunable light source.

[0031] Other aspects of the present invention relate generally to color-tunable multi-LED (light emitting diode) packages (illumination devices / light emitting devices) that can generate light with colors ranging from red to blue and / or color temperatures ranging from 2200 K to 6500 K. More specifically, these embodiments relate to, but are not limited to, multi-LED packages utilizing PC red LEDs such as those described herein.

[0032] According to another aspect of the invention, there is contemplated a lighting device comprising a package, the package comprising: a first LED; a second LED; and a third LED, the first LED generating light having a peak emission wavelength between 620 nm and 640 nm (i.e., red), the second LED generating light having a peak emission wavelength between 500 nm and 565 nm (i.e., green), and the third LED generating light having a CCT (Correlated Color Temperature) of at least 1800 K, the first LED comprising a phosphor-converted LED and a narrowband red phosphor, the phosphor-converted LED comprising an LED chip generating light having a dominant wavelength between 400 nm and 480 nm (i.e., violet to blue).

[0033] The narrow band red phosphor is K2SiF6:Mn 4+ , K2GeF6:Mn 4+ , and K2TiF6:Mn 4+ Includes at least one of the following:

[0034] The first LED may further include a broadband red phosphor.

[0035] The first LED is capable of producing light having a color purity of at least 90%.

[0036] The narrowband red phosphor and the broadband red phosphor can be contained within a single layer.

[0037] The lighting device may comprise a first layer and a second layer, the first layer containing a narrowband red phosphor and the second layer containing a broadband red phosphor.

[0038] The LED chip may comprise a flip chip.

[0039] The second LED can include a phosphor-converted LED and a green phosphor, where the phosphor-converted LED produces light having a dominant wavelength between 400 nm and 480 nm (ie, violet-blue).

[0040] The lighting device may comprise a fourth LED, the fourth LED emitting light having a dominant wavelength between 430 nm and 480 nm (ie blue).

[0041] The third LED may generate light having a CCT of 2000K to 5000K and may include an LED chip and a green-red phosphor, where the LED chip generates light having a dominant wavelength of 400nm to 480nm (i.e., violet-blue).

[0042] The light generated by the device includes a combination of light generated by the first, second, third, and fourth LEDs, and the chromaticity of the light generated by the device is adjustable by controlling the power to the first, second, third, and fourth LEDs, such that the chromaticity coordinates are within 0.003 Δuv from the black body locus for a CRI (Color Rendering Index) of 80 to 98 for a CCT of 1800K to 6500K. As used herein, the "chromaticity" of light, the "color of light," and the "color point" of light may be used interchangeably and may refer to the chromaticity / color of light as represented by its chromaticity coordinates on the CIE (Commission Internationale de I'eclairage) chromaticity diagram. Δuv (delta uv) is a metric that quantifies the degree to which light of a given color temperature is close to the black body locus. As is known, Δuv is the Euclidean distance difference of chromaticity coordinate uv between a test light source and the nearest point on the blackbody locus, and is defined in ANSI_NEMA_ANSLG C78.377-2008: American National Standard for Electric Lamps - Specifications for Chromaticity of Solid-State Lighting Products. Δuv is on the 1976 CIEu,v chromaticity diagram and is a measure of the distance along the iso-CCT line (line of constant color temperature) from the blackbody locus (Planckian locus of blackbody radiation) to the color point of a light of a given CCT (color temperature). A positive Δuv value indicates that the color point is above the blackbody locus (i.e., on the 1931 CIEx,y chromaticity diagram, CIEy is greater than the CIEy value of the blackbody locus) and there is a color shift from the blackbody locus towards yellow / green. Negative values ​​indicate that the color point is below the blackbody locus (i.e., on the 1931 CIEx,y chromaticity diagram, the CIEy is less than the CIEy value of the blackbody locus) and there is a color shift from the blackbody locus towards peach (pink).

[0043] The package may include a lead frame; a housing; and a pair of electrodes, the housing having a first recess, a second recess, a third recess, and a fourth recess, the pair of electrodes being connected to each recess, and each recess including at least one of a first, a second, a third, and a fourth LED.

[0044] Alternatively, the package may comprise a lead frame; a housing; and a common cathode electrode and respective anode electrodes, the housing having first, second, third, and fourth recesses, the common cathode electrode connected to each recess and each anode electrode connected to each recess, each recess containing at least one of the first, second, third, and fourth LEDs.

[0045] In another embodiment, the third LED comprises an LED chip emitting light having a CCT of 5000K to 8000K and emitting light having a dominant wavelength of 400nm to 480nm (ie, violet-blue).

[0046] According to another aspect, a light emitting device comprises: a package with four LEDs generating light having different CIE color points, the device generates white light with different CCTs ranging from 1800K to 8000K by controlling the relative light output of the four LEDs, the chromaticity of the white light generated by the device follows the blackbody locus, and at least one of the LEDs comprises a narrowband red phosphor having a FWHM of less than 55 nm.

[0047] This narrow band red phosphor is K2SiF6:Mn 4+ , K2GeF6:Mn 4+ , and K2TiF6:Mn 4+ The light source may comprise at least one narrow band red phosphor.

[0048] In a preferred embodiment, a first LED generates light having a peak emission wavelength between 620 nm and 640 nm (i.e., red); a second LED generates light having a peak emission wavelength between 500 nm and 565 nm (i.e., green); a third LED generates light having a dominant wavelength between 430 nm and 480 nm (i.e., blue); and a fourth LED generates light having a CCT of at least 1800K.

[0049] According to an additional aspect, the present invention provides a linear lighting apparatus, the lighting apparatus comprising: an elongated structure; and a lighting device as defined herein mounted on a substrate.

[0050] The substrate may comprise a flexible circuit board.

[0051] These and other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the specific embodiments of the invention in conjunction with the accompanying drawings. [Brief description of the drawings]

[0052] [Figure 1] 1A and 1B are schematic representations of a known tunable surface-mount multi-LED package, with FIG. 1A showing a top view and FIG. 1B showing a cross-sectional side view taken along line A-A'. [Diagram 2] 2 is a schematic cross-sectional side view of a packaged single layer red light-emitting device according to one embodiment of the present invention. [Diagram 3] 2 is a schematic cross-sectional side view of a packaged single-layer red light-emitting device according to one embodiment of the present invention. [Figure 4] 2 is a schematic cross-sectional side view of a packaged bi-layer red light-emitting device according to one embodiment of the present invention. [Diagram 5] 2 is a schematic cross-sectional side view of a packaged bi-layer red light-emitting device according to one embodiment of the present invention. [Figure 6] FIG. 2 is a schematic cross-sectional side view of a CSP (chip-scale packaged) bi-layer red light-emitting device according to one embodiment of the present invention. [Figure 7] FIG. 2 is a schematic cross-sectional side view of a CSP (chip-scale packaged) bi-layer red light-emitting device according to one embodiment of the present invention. [Figure 8] FIG. 1 is a CIE 1931 chromaticity diagram illustrating the calculated color purity and dominant wavelength of light of a given chromaticity (color). [Figure 9]9A and 9B show the measured spectra, i.e., intensity (arbitrary units) versus wavelength (nm), for (i) a comparative example Com.1 of a packaged red light-emitting device containing a broadband red phosphor (thick solid line), (ii) a comparative example Com.2 of a packaged red light-emitting device containing a narrowband red fluoride phosphor (thin solid line), (iii) a packaged single-layer red light-emitting device Dev.1 according to one embodiment of the present invention (dashed line), and (iv) a packaged bilayer red light-emitting device Dev.2 according to one embodiment of the present invention (dotted line) - FIG. 9A shows the spectrum for the wavelength portion from 550 nm to 700 nm (i.e., green to red region) and FIG. 9B shows the spectrum for the wavelength portion from 400 nm to 600 nm (i.e., violet to yellow). FIG. 9C is a CIE 1931 chromaticity diagram illustrating the chromaticity (color) of light emitted by (i) a comparative packaged red light-emitting device Com.1 (thick solid line), (ii) a comparative packaged red light-emitting device Com.2 (thin solid line), (iii) a packaged single-layer red light-emitting device Dev,1 (dashed line), and (iv) a packaged bilayer red light-emitting device Dev.2 (dotted line). [Figure 10] Figure 10A is a schematic plan view of a color-tunable multi-LED package light-emitting device utilizing a CSP (chip-scale packaged) bilayer red light-emitting device according to one embodiment of the present invention, and Figure 10B is a CIE 1931 chromaticity diagram illustrating the gamut of light that the color-tunable multi-LED package light-emitting device of Figure 10A can generate. [Figure 11] FIG. 2 is a schematic top view of a color-tunable multi-LED packaged light-emitting device utilizing a CSP (chip-scale packaged) bi-layer red light-emitting device according to one embodiment of the present invention. [Figure 12] FIG. 2 is a schematic plan view of a color-tunable multi-LED packaged light-emitting device utilizing packaged red light-emitting devices according to one embodiment of the present invention. [Figure 13]13A-13C are schematic representations of a color-tunable multi-LED package light-emitting device comprising a PC red LED, a green LED, a blue LED, and a white LED according to one embodiment of the present invention, with FIG 13A showing a top view, FIG 13B showing a side cross-sectional view taken along line BB, and FIG 13C showing a side cross-sectional view taken along line CC. FIG 13D is a CIE 1931 chromaticity diagram illustrating the gamut of light that the color-tunable multi-LED package light-emitting device of FIG 13A-13C can generate. [Figure 14] 14A-14C are schematic representations of a color-tunable multi-LED package light-emitting device comprising a CSP PC red LED, a CSP PC green LED, a blue LED flip chip, and a CSP white LED according to one embodiment of the present invention, where FIG. 14A shows a top view, FIG. 14B shows a side cross-sectional view taken along line DD, and FIG. 14C shows a side cross-sectional view taken along line EE. [Figure 15] Figure 15A is a schematic top view of a color-tunable multi-LED package light-emitting device comprising a PC red LED, a PC green LED, and two PC cool white (CW) LEDs according to one embodiment of the present invention, and Figure 15B is a CIE 1931 chromaticity diagram illustrating the gamut of light that the color-tunable multi-LED package light-emitting device of Figure 15A can generate. [Figure 16] 1 is a schematic representation of a color-tunable linear light-emitting device according to one embodiment of the present invention. [Figure 17]17A-17C are measured characteristics of a color-tunable multi-LED packaged light-emitting device (Pack 1) comprising a PC red LED (red), a PC green LED (green), a blue LED (blue), and a white LED (white); FIG. 17A shows the spectrum, i.e., normalized intensity (arbitrary units) versus wavelength (nm) for the PC red LED (thick solid line), PC green LED (dash-dotted line), blue LED (dotted line), and white LED (dashed line); FIG. 17B is a CIE 1931 chromaticity diagram illustrating the chromaticity (color) generated by the PC red LED (square), PC green LED (diamond), white LED (cross), ANSI CCT center point (solid circle) device gamut (solid line), and the black body locus (dashed line); and FIG. 17C is a CIE 1931 chromaticity diagram illustrating the calculated color purity of light generated by the PC red LED, green LED, blue LED, and white LED. [Figure 18] 18A-18C are diagrams illustrating the measured emission characteristics of a color-tunable multi-LED packaged light emitting device (Pack 1) operable to generate light with a CCT ranging from 2700K to 6500K and a CRI Ra of 90. FIG. 18A illustrates the spectrum, i.e., normalized emission intensity (arbitrary units) versus wavelength (nm), for a CCT of 2700K (dotted line), a CCT of 3000K (dashed line), and a CCT of 4000K. FIG. 18B illustrates the spectrum, i.e., normalized emission intensity (arbitrary units) versus wavelength (nm), for a CCT of 5000K (dotted line), a CCT of 5700K (dashed line), and a CRI Ra of 90. FIG. 18C illustrates the chromaticity (color) of light generated by the color-tunable multi-LED packaged light emitting device (Pack 1) for nominal CCTs of 2700K, 3000K, 4000K, 5000K, 5700K, and 6500K, and a CIE 1931 chromaticity diagram illustrating the emission locus (solid line), blackbody locus (dashed line), and MacAdam ellipse (SCDM-standard deviation of color matching) for CCTs from 2700K to 6500K. [Figure 19]FIG. 1 is a CIE 1931 chromaticity diagram illustrating the color points produced by a color-tunable multi-LED packaged light-emitting device (Pack 1) operable to generate light having nominal CCTs of 2700K, 3000K, 4000K, 5000K, and 6500K, the emission locus (solid line), the blackbody locus (dashed line), and the MacAdam ellipse for CCTs from 2700K to 6500K. [Figure 20] FIG. 20A is a schematic representation of a four-cavity LED package according to one embodiment of the present invention, and FIG. 20B is a schematic representation of the four-cavity LED package leadframe of FIG. 20A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Detailed Description of the Invention Packaged PC Red LED In embodiments, the broadband red phosphor and narrowband red fluoride phosphor particles can be provided as a single layer and / or a mixture within the same layer, and since such devices comprise only one photoluminescent layer, these devices are referred to as "single layer" structure photoluminescent devices.

[0054] In other embodiments, the broadband red phosphor and the narrowband red fluoride phosphor can be included in respective layers, with the layer containing the narrowband red fluoride phosphor being located closer to the LED chip than the layer containing the broadband red phosphor. Because such devices comprise two photoluminescent layers, these devices are referred to as "two-layer" photoluminescent devices.

[0055] Single-layer PC packaged red LED A packaged single layer red light emitting device (PC Red LED) 210 according to one embodiment of the present invention will now be described with reference to Figure 2, which shows a schematic cross-sectional side view of device 210. Light emitting device 210 may comprise a Surface Mounted Device (SMD), such as a 2835 LED package, as shown.

[0056] Light emitting device 210 comprises a leadframe 212 on which a housing (package) 214 is molded. Housing 214 comprises a bottom 216 and sidewall portions 218A, 218B that extend upwardly from opposite edges of bottom 216. The inner surfaces of sidewall portions 218A, 218B slope inwardly relative to their respective vertical axes toward the bottom and, together with the inner surface (floor) of bottom 216, define a cavity in the shape of a frustum of an inverted pyramid or an inverted cone.

[0057] Portions of the lead frame 212 extend laterally outside the edges of the housing 214 to form respective electrical terminals 222, 224 along opposing edges of the package to enable electrical power to the anode (A) and cathode (C) of each LED chip.

[0058] The cavity 220 contains one or more InGaN-based LED chips (violet-blue LED chips) mounted on the floor (bottom inner surface) of the cavity 220. As shown, the LED chips 226 can be electrically connected to the lead frame 212 by bond wires 228. The device 210 can include three InGaN-based LED chips and can have a nominal driving condition of 100 mA, 9V.

[0059] The cavity 220 is filled with a red-light-emitting photoluminescent material 230, which constitutes a single-layer photoluminescent structure. The photoluminescent material layer 230 may include a light-transmitting (transparent) encapsulant, such as a silicone material, in which the red-light-emitting photoluminescent material 230 is dispersed.

[0060] In accordance with the present invention, the red photoluminescent material 230 includes a combination of a narrowband red fluoride phosphor and a red phosphor, such as a broadband red phosphor, that has a higher absorption efficiency than the narrowband red fluoride phosphor. Details of suitable narrowband red and broadband red phosphors are provided below. The photoluminescent layer 230 can contain materials other than the photoluminescent (phosphor) material, such as light scattering particles or light diffusing materials.

[0061] The single layer device 210 can be fabricated by dispersing a curable light-transmitting liquid material, such as silicone, containing a mixture of narrowband red fluoride phosphor and broadband red phosphor into the cavity 220 .

[0062] 3, there is shown a packaged single layer red light emitting device 310 formed in accordance with another embodiment of the present invention. This embodiment differs from FIG. 2 only in that the LED chip 326 comprises an LED flip chip.

[0063] Double-layer PC packaged red LED A packaged bi-layer red light emitting device (PC Red LED) 410 according to one embodiment of the present invention will now be described with reference to FIG. 4, which shows a schematic cross-sectional view of the device 410.

[0064] 2 in that the photoluminescent material layer 430 is comprised of a two-layer photoluminescent structure comprising a first photoluminescent layer 430A and a second photoluminescent layer 430B. The first photoluminescent layer 430A is closer to the LED chip 426 than the second photoluminescent layer 430B, i.e., the first photoluminescent layer 430A is closer to the LED chip 426 (i.e., is a proximal layer) while the second photoluminescent material layer 430B is distal to the LED chip 426 (i.e., is a distal layer).

[0065] In terms of photoluminescent (phosphor) material, the first photoluminescent layer 430A contains only or substantially (at least 90% by weight) only narrow-band red fluoride phosphor. More specifically, in an embodiment, the first photoluminescent layer 430A contains K2SiF6:Mn 4+ The first photoluminescent layer 430A contains only K2SiF6:Mn fluoride phosphor dispersed in dimethyl silicon. However, other materials, such as light diffusing (scattering) materials, may be added to the first photoluminescent layer 430A, although the amount of other materials is typically no more than 30% by weight of the narrowband red fluoride phosphor. Furthermore, in this embodiment, the first photoluminescent layer 430A is made of K2SiF6:Mn fluoride phosphor dispersed in dimethyl silicon. 4+ The first photoluminescent layer 430A is immediately adjacent to the LED chip 426 and may be in direct contact with the LED chip 426 as shown in Figure 4. There are no other photoluminescent materials or photoluminescent material-containing layers between the first photoluminescent layer 430A and the LED chip 426.

[0066] The second photoluminescent layer 430B contains a broadband red phosphor and is dispersed over the first photoluminescent layer 430A.

[0067] Compared to the single-layer device 210, for example, as shown in FIG. 2, in the single-layer light-emitting device, the narrow-band red fluoride phosphor and the broad-band red phosphor, including the mixture, are equally exposed to the excitation light, for example, blue excitation light, because each is located at the same position (in a layer) relative to the LED chip. The narrow-band red fluoride phosphor has a much lower blue absorption efficiency than the broad-band red phosphor, so a larger amount of the narrow-band red fluoride phosphor is required to convert sufficient blue light into red emission that needs to be attributed to the narrow-band red fluoride phosphor. In contrast, in the two-layer light-emitting device 410, the narrow-band red fluoride phosphor in the separate individual layer 430A is individually exposed to blue excitation light; thus, a larger percentage of the blue excitation light from the blue LED chip 426 can be absorbed by the narrow-band red phosphor, and the remaining blue excitation light can penetrate the photoluminescent layer 430B containing the broad-band red phosphor. Advantageously, in the two-layer photoluminescent structure, the first photoluminescent layer 430A can more effectively convert blue excitation light into narrow-band red light, and the amount / usage of narrow-band red fluoride phosphor can be significantly reduced (up to about 40%) compared to the single-layer photoluminescent configuration (FIG. 2). An additional advantage of the two-layer photoluminescent structure is that the second photoluminescent layer 430B completely covers the first photoluminescent layer 430A, which effectively isolates the narrow-band red fluoride phosphor contained in the first photoluminescent layer 430A from direct contact with water / moisture in the surrounding environment. Such a two-layer structure provides an effective solution to address the poor moisture reliability of narrow-band red fluoride phosphor.

[0068] 5, there is shown a packaged bilayer light emitting device 510 formed in accordance with another embodiment of the present invention. This embodiment differs from FIG. 4 only in that the LED chip 526 comprises an LED flip chip.

[0069] CSP (Chip Scale Package) PC Red LED Although the above embodiments have been described with respect to packaged PC red LED devices, embodiments of the present invention find utility in chip-scale packaged light emitting devices. As used herein, a CSP configuration is a chip-scale packaging configuration that does not include a lead frame. In a CSP configuration, the LED chip may comprise an integrated component of the package. For example, one or more layers of material may be applied directly to the surface of a flip chip to form a packaged device. A particular advantage of the CSP configuration is the small size of the packaged device, which is comparable to the chip size.

[0070] FIG. 6 shows a side view of a CSP bilayer red light emitting device 610 according to an embodiment of the present invention. In this embodiment, a first photoluminescent layer 630A containing a narrowband red fluoride phosphor is applied as a layer of uniform thickness directly onto at least the primary light emitting surface (top surface as shown) of an LED flip chip 626 to cover this surface. A second photoluminescent material layer 630B containing a broadband red phosphor is applied or deposited (fabricated) as a layer of uniform thickness onto the first photoluminescent layer 630A to cover this layer. As shown, the device 610 can further include a light reflecting layer 632, e.g., white silicone or epoxy, covering the four sides of the LED chip to prevent emission of excitation light from these sides. In other embodiments, a light reflecting layer can cover the edges of the first and second photoluminescent layers to prevent emission of excitation light from these edges.

[0071] 7 shows a side view of a CSP bilayer red light emitting device 710 according to an embodiment of the present invention. In this embodiment, a first photoluminescent layer 730A containing a narrowband red fluoride phosphor is applied or deposited (fabricated) as a layer of uniform thickness directly onto at least the primary light emitting surface (top surface as shown) and four side light emitting surfaces of an LED flip chip 726 to cover these surfaces. A second photoluminescent layer 730B containing a broadband red phosphor is applied or deposited (fabricated) as a layer of uniform thickness onto the top and side surfaces of the first photoluminescent layer 730A to cover these surfaces. The first and second photoluminescent layers 730A, 730B can be in the form of conformal coatings.

[0072] Narrowband red fluoride phosphor As used herein, narrow band red phosphor refers to a photoluminescent material that generates red light having a full width at half maximum (FWHM) emission intensity of about 5 nm to about 20 nm in response to stimulation with excitation light. As described herein, the narrow band red phosphor is a manganese-activated potassium hexafluorosilicate phosphor (KSF) - K2SiF6:Mn 4+ Other manganese-activated fluoride narrow-band red phosphors include manganese-activated potassium hexafluorogermanate phosphor (KGF)-K2GeF6:Mn 4+ and manganese-activated potassium hexafluorotitanate phosphor (KTF) - K2TiF6:Mn 4+ may include.

[0073] Broadband Red Phosphor As used herein, a broadband red phosphor refers to a photoluminescence material that generates red light having a full width at half maximum (FWHM) emission intensity from about 50 nm to about 120 nm in response to stimulation by excitation light. As described above, the broadband red phosphor can include a rare earth-activated broadband red phosphor, which can be excited by blue light and, in response to this excitation, emits light having a peak emission wavelength λ within the range of about 620 nm to about 640 nm, i.e., within the red region of the visible spectrum. p The rare earth-activated red photoluminescence material can include, for example, a europium-activated silicon nitride-based phosphor, a group IIA / group IIB sulfoselenide-based phosphor, or a silicate-based phosphor. Examples of broadband red phosphors are listed in Table 1.

[0074] In some embodiments, the europium-activated silicon nitride-based phosphor includes the general formula CaAlSiN3:Eu 2+ (1:1:1:3 nitride) calcium aluminum silicon nitride phosphor (CASN: Calcium Aluminum Silicon Nitride). The CASN phosphor can be doped with other elements such as strontium (Sr) to have the general formula (Sr,Ca)AlSiN3:Eu 2+ and can be made to be.

[0075] Alternatively, the rare earth-activated red phosphor can include a nitride-based phosphor with a general composition (Sr,Ba)2Si5N8:Eu 2+ (2:5:8 nitride).

[0076] The rare earth-activated red phosphor can also include a group IIA / group IIB sulfoselenide-based phosphor. The first example of a group IIA / group IIB sulfoselenide-based phosphor material has the composition MSe 1-x S x Eu, where M is at least one of Mg, Ca, Sr, Ba, and Zn and 0 < x < 1.0. A specific example of this phosphor material is the CSS phosphor (CaSe 1-x S x: It is (Eu). The emission wavelength of the CSS phosphor can be adjusted from 600 nm to 650 nm by changing the S / Se ratio in the composition.

[0077] In some preferred examples, the rare-earth activated red phosphor can include a silicate system with a general composition of (Sr 1-x M x ) y Eu z SiO5, where 0 < x ≦ 0.5, 2.6 ≦ y ≦ 3.5, 0.001 ≦ z 0.5, and M is one or more divalent metals selected from the group consisting of Ba, Mg, Ca, and Zn.

[0078]

Table 1

[0079] Color purity and dominant wavelength Color purity, or chroma, provides a measure of how closely the color tone of the light of a given color (chromaticity) resembles the color (monochromatic) of the spectrum corresponding to the light of the dominant wavelength λ d . Color purity can have values from 0% to 100%. Figure 8 is the CIE 1931 chromaticity diagram illustrating a method for calculating the color purity and dominant wavelength of the light of a given chromaticity (color).

[0080] Referring to Figure 8, the color point (chromaticity) of the light of a given color is shown on the chromaticity diagram by the cross 834, and the "white standard illuminant" is shown at point 836. The "white standard illuminant" used in this specification is of equal energy (flat spectrum) and has color space coordinates CIE(1 / 3, 1 / 3). The straight line 838 (dashed line) connecting the color points 834 and 836 of the chromaticity intersects the outer curve boundary (periphery) of the CIE color space at two points. The intersection point 840 closer to the given color CIE(x, y)834 is the dominant wavelength λ d corresponding to the wavelength of the color of the pure (pure) spectrum (monochromatic) at this intersection point. The intersection point 842 on the opposite side within the color space corresponds to the complementary dominant wavelength λ c and the complementary dominant wavelength λ cWhen added in the proper proportion to a given color, it produces the color of the white standard illuminant.

[0081] The outer curved boundary of the chromaticity diagram is the monochromatic (spectral) locus, with numbers indicating wavelengths in nanometers (nm). Monochromatic light (i.e., anything that lies on the spectral locus) has a color purity of 100, whereas the color purity of the "white standard illuminant" 834 is 0. The color purity of light with chromaticity coordinates CIE(x, y) plotted on the chromaticity diagram is the chromaticity of the "white standard illuminant" 836 at a dominant wavelength λ d This is the ratio of the distance from the "white standard illuminant" 836 to the color point 834 to the distance to the intersection point 840 corresponding to

[0082] Experimental Test Data In this specification, the following nomenclature is used to refer to the PC red light-emitting devices: Com.# refers to a comparative PC red light-emitting device comprising a single red phosphor (i.e., a broadband red phosphor or a narrowband red fluoride phosphor), and Dev.# refers to a light-emitting device according to the present invention comprising a combination of a narrowband red fluoride phosphor and a broadband red phosphor.

[0083] The comparative PC red light emitting device (Com.#) and the PC red light emitting device according to the present invention (Dev.#) are composed of SMD2835 packaged devices containing four blue LED chips connected in series. Each device is nominally 1.2 W (rated drive conditions are 100 mA and a forward drive voltage V of 12 V). f (It is.)

[0084] The red phosphor used in the test device was KSF (K2SiF6:Mn 4+ ) narrowband red fluoride phosphor and CASN(Ca 1-x Sr x AlSiN3:Eu) broadband red phosphor.

[0085] For the comparative devices, Com.# red phosphor (KSF or CASN) was mixed in phenyl silicone and the mixture dispensed into the 2835 package filling the LED cavity.

[0086] For the single layer device (Dev.1): a mixture of KSF and CASN phosphors is contained in phenyl silicone and dispensed into a 2835 package to fill the cavity of the LED.

[0087] For the bilayer device (Dev.2): KSF phosphor is mixed in phenyl silicone and dispensed into the 2835 package to partially fill the LED cavity. The KSF phosphor layer is cured in an oven. CASN phosphor is mixed with phenyl silicone and then dispensed onto the KSF to completely fill the LED cavity and then cured in an oven.

[0088] optical performance The test method involves measuring the total luminance of a PC red emitting device in an integrating sphere.

[0089] Table 2 lists the compositions of the comparative devices Com.1 and Com.2, and the devices Dev.1 and Dev.2 according to the invention. CASN 630, CASN 650, and CASN 655 refer to CASN phosphors with peak emission wavelengths of 630 nm, 650 nm, and 655 nm, respectively. The weight percent values ​​in Table 2 are the weight percent of the total phosphor weight. The weight values ​​in Table 2 are the weight of the KSF phosphor normalized to the weight of the KSF phosphor in the comparative PC red LED Com.2.

[0090] As can be seen from Table 2, in terms of phosphor composition: Com.1 comprises a single layer phosphor structure including 100% by weight of CASN 630; Com.2 comprises a single layer phosphor structure including 100% by weight of KSF; Dev.1 comprises a single layer phosphor structure containing a combination of 67% by weight of KSF and 33% by weight of CASN 650; Dev.2 comprises a two-layer phosphor structure having a first phosphor layer including 61% by weight of KSF and a second phosphor layer including 39% by weight of CASN 655.

[0091] [Table 2]

[0092] Table 3 lists the measured optical performance of PC red light emitting devices (PC red LEDs) Com.1, Com.2, Dev.1, and Dev.2. Figures 9A and 9B show the measured spectra, i.e., intensity (arbitrary units) versus wavelength (nm), for (i) a comparative packaged red light emitting device Com.1 containing a broadband red phosphor (thick solid line), (ii) a comparative packaged red light emitting device Com.2 containing a narrowband red fluoride phosphor (thin solid line), (iii) a packaged single layer red light emitting device Dev.1 according to an embodiment of the present invention (dashed line), and (iv) a packaged bilayer red light emitting device Dev,2 according to an embodiment of the present invention. Figure 9A shows the wavelength portion of the spectrum at wavelengths from 550 nm to 700 nm (i.e., green-red region). Figure 9B shows the wavelength portion of the spectrum at wavelengths from 400 nm to 600 nm (i.e., blue-violet-yellow), illustrating "blue light pass". FIG. 9C is a CIE 1931 chromaticity diagram illustrating the chromaticity (color) of light generated by (i) comparative packaged red light-emitting device Com.1 (solid circle), (ii) comparative packaged red light-emitting device Com.2 (cross), (iii) packaged single-layer red light-emitting device Dev.1 (solid triangle), (iv) packaged double-layer red light-emitting device Dev.2 (solid diamond), the blackbody locus (dashed line), and the boundaries of the chromaticity gamut (solid line).

[0093] [Table 3]

[0094] As can be seen from Table 3, the comparative device Com.1, which contains only a broadband red phosphor (CASN 630), has a peak emission wavelength λ of 639 nm. p 729lm (100%) luminous flux and 10.0lm / W luminous efficacy, FWHM of 67nm, dominant wavelength λ of 620nm d , and produces red light with a color purity of 99.7%. In comparison, the comparative device Com.2, which contains only narrow-band red fluoride phosphor (KSF), produces a peak emission wavelength λ of 633 nm.p The narrowband red fluoride phosphor (Com.2) produces red light with an increased luminous flux of 13.89 lm (190%) and luminous efficacy of 11.5 lm / W, a FWHM of 7 nm, a dominant wavelength of 627 nm, and a color purity of 87.3%. Note that, as might be expected, the use of the narrowband red fluoride phosphor (Com.1) results in a significant (90%) increase in lumen output / efficacy, a reduction in FWHM (from 67 nm to 7 nm), and a decrease in color purity (87.3% compared to 99.7%) compared to the use of the broadband red phosphor (Com.1).

[0095] 9B, for Com.1, there is no evidence of blue-violet / blue light (400-500 nm) in the final emission spectrum (thick solid line), indicating that all of the blue light generated by the LED is converted to red light, i.e., there is no evidence of "blue light pass" in the emission product of the Com.1 device. In contrast, for Com.2, the emission spectrum (thin solid line) shows a clear peak at 944 (λ p Com.2 has a wavelength of approximately 435 nm (approximately 435 nm) in the blue-violet / blue region of the spectrum, with peak 944 due to the blue light generated by the LED that is not converted, the so-called "blue light pass". The large drop in color purity of the red light produced by Com.2 compared to Com.1 (87.3% compared to 99.7%) is due to the unconverted blue light 944, which reduces the chromaticity CIE x of the light and moves the chromaticity of the light (color point 834 - Figure 8) further away from the curve boundary of the chromaticity diagram, thereby reducing the color purity. Increasing the weight loading of narrowband red fluoride phosphor (KSF) relative to the binder (silicone) from 70% to 80% only increases the color purity of the light produced by Com.2 to a value of 95%. Thus, a large increase in the KSF loading alone significantly increases the cost of production without resulting in a significant increase in the light performance / purity of the device. Therefore, a combination of a narrowband red fluoride phosphor (eg, a manganese-activated fluoride narrowband red phosphor) with a red phosphor having a higher absorption efficiency, such as a broadband red phosphor, is advantageous.

[0096] As can be seen from Table 3, the single layer device Dev.1, which contains a combination of narrowband red fluoride phosphor and broadband red phosphor (CASN 650), has a peak emission wavelength λ of 633 nm. p 9B, Dev.1 emits red light with a peak of 946 (λ 1 ) in the blue-violet / blue region of the spectrum, a luminous efficacy of 14.89 lm (204%) and 12.3 lm / W, a FWHM of 27 nm, a dominant wavelength of 619 nm, and a color purity of 94.2%. p 445 nm), with peak 946 due to unconverted blue light, "blue light pass", but the intensity of peak 946 is much smaller (about half) than peak 944 of Com.2. The increase in color purity of the red light generated by Dev.1 compared to Com.2 (94.2% compared to 87.3%) is due to the reduction in unconverted blue light in the final luminescence product. As shown in FIG. 9C, the reduction in unconverted blue light increases the chromaticity CIE x value of the light generated by Dev.1 (934a - solid triangle) compared to Com.2 (cross) and moves the chromaticity point of the light towards the chromaticity gamut boundary curve (solid line) of the chromaticity diagram, thereby increasing the color purity. The increase in color purity of the light generated by Dev,1 compared to Com.2 is due to the inclusion of a broadband red phosphor, which reduces the intensity of unconverted blue light 946 in the final luminescence product. As can be seen from Table 2, the inclusion of the broadband red phosphor also reduces the amount (weight) of narrowband red fluoride phosphor used (34% weight reduction compared to Com.2).

[0097] As can be seen from Table 3, the bilayer device Dev.2, which contains a combination of narrowband red fluoride phosphor and broadband red phosphor (CASN 650), has a peak emission wavelength λ of 633 nm. p 17.72lm (243%) luminous flux and 14.5lm / W luminous efficacy, FWHM of 7.49nm, dominant wavelength λ of 621nm d , and produces red light with a color purity of 97.7%. Referring to FIG. 9B, Dev. 2 produces a peak 948 (λ p445 nm) with a peak 948 due to unconverted blue light - "blue light pass" - but the peak 948 is broadened and much less intense (about one-fourth) than the intensity of peak 944 of Com.2. The increase in color purity of the red light produced by the bilayer device Dev.2 compared to the single layer device Dev.1 (97.7% compared to 94.2%) is due to the reduction in unconverted blue light 948 in the final luminescence product. As shown in FIG. 9C, the reduction in unconverted blue light increases the chromaticity CIE x value of the light produced by Dev,2 (934b - diamonds) compared to Dev,1 (934a - triangles) and shifts the chromaticity point 934b of the light towards the chromaticity gamut boundary curve (solid line) of the chromaticity diagram, thereby increasing the color purity. The reduction in "blue light pass" is due to the bilayer photoluminescent structure, in which the narrowband red fluoride phosphor is provided in a separate layer adjacent to the LED chip. Such a configuration effectively increases the absorption efficiency of the narrowband red fluoride phosphor, since it does not compete with the broadband red phosphor for blue photons, as in the case of the single layer photoluminescent structure. Furthermore, as can be seen from Table 3, the bilayer photoluminescent structure can reduce the amount (weight) of narrowband red fluoride phosphor used (40% weight reduction compared to Com. 2) while increasing color purity and intensity / luminous efficiency (243% compared to 204%).

[0098] In summary, it has been found that red light emitting devices according to embodiments of the present invention, including a combination of a narrowband red fluoride phosphor and a broadband red phosphor, can provide numerous advantages, including, but not limited to: (1) a significant reduction (approximately 40%) in the amount of narrowband red fluoride phosphor used; (2) a significant reduction, or even elimination, of "blue light pass," which results in an increase in the color purity of the red light generated by the device; (3) a significant increase in the light intensity / luminous efficiency of the device; and (4) color purity that is comparable to or better than that of a PC red LED that utilizes only a broadband red phosphor.

[0099] Color-tunable multi-LED package light-emitting device Phosphor-converted red LEDs (PC red LEDs) according to embodiments of the present invention find utility as red light sources in light emitting devices, such as, for example, an RGB (red, green, blue) multi-LSD packaged light emitting device comprising a red LED, a green LED, and a blue LED. As described herein, the PC red LED can be constructed as a packaged device or a CSP (chip-scale packaged) device having a single or double layer photoluminescent structure. The green LED can be constructed as a packaged or CSP (chip-scale packaged) phosphor-converted LED (PC green LED) having a single layer photoluminescent structure comprising a green photoluminescent material (phosphor) covering a blue-violet to blue LED chip. The green phosphor can be, for example, a green silicate phosphor ((Sr 1-x Ba x )2SiO4:Eu), β-SiAlON phosphor, or green-emitting YAG (Yttrium Aluminum Garnet) phosphor ((Y,Ba) 1-x (Al 1-y Ga y )5O 12 :Ce x Alternatively, the green LED may comprise a direct-emitting green LED chip (e.g., an InGaN-based LED chip). The blue LED typically comprises an InGaN-based LED chip or a flip chip.

[0100] FIG. 10A shows a schematic plan view of a color-tunable multi-LED package light-emitting device 1050 utilizing a red light-emitting device (PC red LED). The light-emitting device 1050 comprises a package (e.g., SMD) 1014 comprising a lead frame and a housing 1052 defining a single cavity (recess) 1020 (e.g., circular as shown), which contains a PC red LED 1010, a green LED 1054, and a blue LED 1056. The PC red LED 1010 can be a PC red LED according to an embodiment of the invention, such as a single or double layer CSP (chip-scale packaged) red light-emitting device, such as the CSP devices of FIG. 6 or FIG. 7. The green LED can be a CSP PC green LED with a broadband green phosphor coated on the LED flip chip. The green LED 1054 can be a CSP PC green LED with a broadband green phosphor coated on the LED flip chip. The green phosphor produces light having a peak emission wavelength of 500 nm to 565 nm. Alternatively, the green LED may comprise a direct-emitting green LED chip (e.g., an InGaN-based LED chip). The blue LED 1056 typically comprises an InGaN-based LED chip and produces light having a dominant wavelength of 430 nm to 480 nm. The cavity 1020 may be filled with an optically transparent medium (e.g., silicone) to provide environmental protection for the red LED 1010, the green LED 1054, and the blue LED 1056. As shown, the package 1014 typically includes respective anode and cathode electrical terminals 1022, 1024 to allow electrical power to be individually provided to the anode and cathode of each of the red (R), green (B), and blue LEDs 1010, 1054, 1056.

[0101] The light emitting device 1050 can generate light of colors ranging from blue to red, as well as light of different color temperatures. FIG. 10B is a CIE 1931 chromaticity diagram, illustrating the gamut (color / color temperature) of light that the light emitting device 1050 can generate. The CIE chromaticity diagram shows the chromaticity (color point) 1057R of the red light generated by a PC red LED, the chromaticity (color point) 1057G of the green light generated by a PC green LED, and the chromaticity (color point) 1057B of the blue light generated by a blue LED. A line 1058 connecting points 1058R, 1057G, and 1057B defines a triangle that represents the gamut of chromaticity (color) / color temperature of light that the light emitting device 1050 can generate - i.e., the device can generate light of any color / color temperature within or on the boundary of this triangle. As can be noted from the chromaticity diagram, device 1050 is capable of producing light with color temperatures that lie on the blackbody locus (dashed line) and that correspond to ANSI CCT (American National Standards Institute Correlated Color Temperature) center points within or on the boundary of this triangle.

[0102] FIG. 11 shows a schematic plan view of a color-tunable multi-LED package light-emitting device 1150 utilizing a red light-emitting device (PC red LED). The light-emitting device 1150 comprises a package 1114 having three cavities 1120a, 1120b, 1120c, each of which contains a phosphor-converted red LED 1110, a green LED 1154, and a blue LED 1156. As shown, the PC red LED 1110 may be a PC red LED according to an embodiment of the present invention, such as a single-layer or double-layer CSP (chip-scale packaged) red light-emitting device, such as the CSP devices of FIG. 6 or FIG. 7. The green LED 1154 may be a CSP PC green LED or a direct-emitting green LED (e.g., an InGaN-based LED chip). The blue LED 1056 typically comprises an InGaN-based LED chip and generates light having a dominant wavelength between 430 nm and 480 nm. Each cavity 1120a, 1120b, 1120c can be filled with an optically transparent medium (e.g., silicone) to provide environmental protection for the red LED 1110, the green LED 1154, and the blue LED 1156. As shown, the package 1114 generally includes respective anode electrical terminals 1122R, 1122G, 1122B and cathode electrical terminals 1124R, 1124G, 1124B to allow independent power supply to the anode and cathode of each of the red (R) LED 1110, the green (G) LED 1154, and the blue (B) LED 1156. Like the light emitting device 1050 of FIG. 10, the light emitting device 1150 can generate light in a range of colors from blue to red, and of different color temperatures - i.e., light with color temperatures within or on the boundaries of the triangle on the chromaticity diagram (FIG. 10B).

[0103] FIG. 12 shows a schematic plan view of a color-tunable multi-LED packaged light-emitting device 1250 utilizing a red light-emitting device (PC red LED). The light-emitting device 1250 comprises a package 1214 having three cavities 1220a, 1220b, 1220c, each of which contains a PC red LED 1210, a green LED 1254, and a blue LED chip 1256. As shown, the phosphor-converted red LED 1210 may comprise a PC red LED according to an embodiment of the invention, such as a single-layer or dual-layer light-emitting device, such as the packaged device of FIGS. 2-5, in which the cavity 1220a is filled with a narrowband red fluoride phosphor and a broadband red phosphor. As shown, the green LED 1254 may comprise a PC green LED, such as the packaged device with the cavity 1220b filled with a green phosphor. The blue LED generally comprises an InGaN-based LED chip and generates light having a dominant wavelength between 430 nm and 480 nm. The cavity 1220c may be filled with an optically transparent medium (e.g., silicone) to provide environmental protection for the blue LED 1256. As shown, the package 1214 generally comprises respective anode electrical terminals 1222R, 1222G, 1222B and cathode electrical terminals 124R, 1224G, 1224B to allow power to be independently provided to the anode and cathode of each of the red (R) LED 1210, green (G) LED 1254, and blue (B) LED 1256. Like the light emitting device 1050 of FIG. 10, the light emitting device 1250 may generate light in a range of colors from blue to red, as well as light of different color temperatures - i.e., light with color temperatures within or on the boundary of the triangle on the chromaticity diagram (FIG. 10B).

[0104] 13A-13C are schematic representations of a color-tunable multi-LED package light emitting device with PC red, green, blue, and white LEDs, according to one embodiment of the present invention, with FIG. 13A showing a top view, FIG. 13B showing a side cross-sectional view along BB, and FIG. 13C showing a side cross-sectional view along CC. The light emitting device 1350 comprises a package 1314 comprising a lead frame 1312 and a housing 1352 molded onto the lead frame. The housing 1352 comprises a first cavity 1320a, a second cavity 1320b, a third cavity 1320c, and a fourth cavity 1320d, which respectively contain a phosphor-converted red LED 1310, a green LED 1354, a blue LED 1356, and a white LED 1359. As shown, the package 1314 comprises a first pair of anode and cathode electrical terminals 1322aR, 1324aR connected to the first cavity 1320a, a second pair of anode and cathode electrical terminals 1322bG, 1324bG connected to the second cavity 1320b, a third pair of anode and cathode electrical terminals 1322cB, 1324cB connected to the third cavity 1320c, and a fourth pair of anode and cathode electrical terminals 1322dW, 1324dW connected to the fourth cavity 1320d, enabling independent power supply to the red (R) LED 1310, the green (G) LED 1354, the blue (B) LED 1356, and the white (W) LED 1359.

[0105] As shown, the phosphor-converted red LED 1310 may comprise a PC red LED 1310 according to an embodiment of the invention, such as a single layer or dual layer light emitting device, such as the packaged device of Figures 2-5, in which a first cavity 1320a contains a violet-blue LED chip 1326, the first cavity 1320a being filled with a narrowband red fluoride phosphor and a broadband red phosphor photoluminescent layer. As shown, the green LED 1354 may comprise a PC green LED, such as a packaged device, in which a second cavity 1320b contains a violet-blue LED chip 1326, the second cavity 1320b being filled with a red phosphor photoluminescent layer 1360 covering the blue-violet LED chip 1326. The blue LED 1356 comprises a blue LED chip, which generates light having a dominant wavelength of 430 nm to 480 nm. The third cavity 1320c can be filled with a light-transmitting medium (e.g., silicone) to provide environmental protection for the blue LED chip 1356. As shown, the white LED 1359 can comprise a packaging device in which a fourth cavity 1320d contains a violet-blue LED chip 1326, which is filled with a green-red phosphor photoluminescent layer covering the blue-violet LED chip 1326. The white LED 1359 is configured to generate warm white (WW) light having a CCT (color temperature) of 2000K to 4000K.

[0106] The light emitting device 1350 can generate light of colors (chromaticities) ranging from blue to red, as well as light of different color temperatures. Figure 13D is a CIE 1931 chromaticity diagram illustrating the gamut (color / color temperature) of light that the light emitting device 1350 can generate. The CIE chromaticity diagram in Figure 13D shows the chromaticity (color point) 1357R (solid diamond) of red light generated by a PC red LED, the chromaticity (color point) 1357G (solid diamond) of green light generated by a PC green LED, the chromaticity (color point) 1357B (solid diamond) of blue light generated by a blue LED, and the chromaticity (color point) 1357W (cross) of light generated by a white LED. The lines 1358 connecting points 1357R, 1357G, and 1357B define a triangle that represents the gamut of chromaticity / color temperature of light that the light emitting device 1350 can generate - i.e., the device can generate light of any chromaticity / color temperature that is within or on the boundary of the triangle. Note that the white LED does not increase the color gamut of the device, since its color point 1357W is within the triangle. However, the inclusion of the white LED simplifies the generation of light of other color temperatures by adding green / blue light to the light generated by the white LED, and the generation of light with a higher Color Rendering Index (CRI) Ra by adding red light to the light generated by the white LED.

[0107] 14A-14C are schematic representations of a color-tunable multi-LED package light-emitting device including a CSP PC red LED, a CSP PC green LED, a blue LED flip chip, and a CSP white LED, with FIG. 14A showing a top view, FIG. 14B showing a side cross-sectional view taken along line DD, and FIG. 14C showing a side cross-sectional view taken along line EE, according to an embodiment of the present invention. Light-emitting device 1450 is similar to light-emitting device 1350 and includes a chip-scale packaged (CSP) LED. As shown, phosphor-converted red LED 1410 is comprised of a CSP PC red LED according to an embodiment of the present invention, such as a single-layer or dual-layer red light-emitting device, such as the CSP devices of FIGS. 6 and 7, with a blue-violet LED flip chip 1426 having a photoluminescent layer 1430 of narrowband red fluoride phosphor and broadband red phosphor on at least the light-emitting surface of the LED flip chip. The first cavity 1420a can be filled with an optically transparent medium (e.g., silicone) to provide environmental protection for the CSP PC red LED 1410. As shown, the CSP PC green LED 1454 can include a violet-blue LED flip chip 1426 having a green phosphor photoluminescent layer 1460 on at least the light emitting surface of the LED flip chip 1426. The second cavity 1420b can be filled with an optically transparent medium (e.g., silicone) to provide environmental protection for the CSP PC green LED 1454. The blue LED 1456 includes a blue LED chip that generates light having a dominant wavelength of 430 nm to 480 nm. The third cavity 1420c can be filled with an optically transparent medium (e.g., silicone) to provide environmental protection for the blue LED chip 1456. As shown, the CSP white LED 1459 can include a violet-blue LED flip chip 1426 having a green-red phosphor photoluminescent layer 1462 on at least the light emitting surface of the LED flip chip 1426 .The fourth cavity 1420d can be filled with a light transmissive medium (e.g., silicone) to provide environmental protection for the CSP white LED 1459. The white LED 1459 can be configured to generate warm white (WW) light with a CCT (color temperature) of 2000K to 5000K. The package 1414 generally comprises anode electrical terminals 1422aR, 1422bG, 1422cB, and 1422dW connected to each cavity 1420a, 1420b, 1520c, and 1420d, respectively, and cathode electrical terminals 1424a, 1424b, 1424c, and 1424d connected to each cavity 1420a, 1420b, 1520c, and 1420d, respectively, to enable power to be supplied to the anodes and cathodes of each of the red (R) LED 1410, green (G) LED 1454, blue (B) LED 1456, and white LED 1459. Like light emitting device 1250 of FIG. 12, light emitting device 1450 can emit light of colors ranging from blue to red, as well as light of different color temperatures - i.e., light of colors / color temperatures within or on the boundary of the triangle on the chromaticity diagram (FIG. 10B).

[0108] 15A is a schematic top view of a color-tunable multi-LED package light-emitting device 1550 including a PC red LED, a PC green LED, and two cool white (CW) LEDs, according to one embodiment of the present invention. The light-emitting device 1550 includes a package 1514 including a lead frame and a housing 1552 molded on the lead frame. The housing 1552 includes a first cavity 1520a, a second cavity 1520b, a third cavity 1520c, and a fourth cavity 1520d, which respectively contain a phosphor-converted red LED 1510, a phosphor-converted green LED 1554, a first CW LED 1564, and a second CW LED 1564. As shown, the phosphor-converted red LED 1510 can be a PC red LED according to an embodiment of the invention, such as a single or dual layer red light emitting device, such as the packaged devices of Figures 2-5, where a first cavity 1520a includes a violet-blue LED chip 1526 and is filled with a narrowband red fluoride phosphor and a broadband red phosphor photoluminescent layer over the violet-blue LED chip 1526. As shown, the green LED 1554 can be a PC green LED, such as a packaged device, where a second cavity 1520b includes a violet-blue LED chip 1526 and is filled with a green phosphor photoluminescent layer over the violet-blue LED chip 1526. As shown, the first and second CW LEDs 1564 can comprise a packaging device in which the third and fourth cavities each contain a violet-blue LED chip 1526 and are filled with a green-yellow phosphor photoluminescent layer covering the violet-blue LED chip 1526. The first and second CW LEDs 1564 can be configured to generate white light with a CCT (color temperature) of 5000K to 8000K. The first and second CW LEDs 1564 can generate CW light of the same CCT or CW light of different CCTs.The package 1514 generally includes respective anode electrical terminals 1522aR, 1522bG, 1522cCW, and 1522dCW and cathode electrical terminals 1524aR, 1524bG, 1524cCW, and 1524dCW connected to each cavity to enable independent supply of power to the anode and cathode of each of the red (R) LED 1510, the green (G) LED 1554, and the first and second CW LEDs 1564.

[0109] The light emitting device 1550 can generate light of colors ranging from green to red, as well as light of different color temperatures. FIG. 15B is a CIE 1931 chromaticity diagram illustrating the gamut (color / color temperature) of light that the light emitting device 1550 can generate. The chromaticity diagram of FIG. 15B shows the chromaticity (color point) 1557R (solid diamond) of red light generated by a PC red LED, the chromaticity (color point) 1557G (solid diamond) of green light generated by a PC green LED, and the chromaticity (color point) 1557CW (solid diamond) of light generated by a CW LED. A line 1558 connecting points 1557R, 1557G, and 1557CW defines a triangle representing the gamut (color) / color temperature (chromaticity) of light that the light emitting device 1550 can generate - i.e., the device can generate light of any chromaticity (color) / color temperature that is within or on the boundary of the triangle. The inclusion of a CW LED can simplify the generation of light of other color temperatures by adding green / red light to the light generated by the CW LED.

[0110] FIG. 16 is a schematic top view of a color-tunable linear light-emitting device 1668 according to one embodiment of the present invention. The color-tunable linear light-emitting device 1668 comprises a linear (elongated) substrate 1670, such as a strip of a Metal Core Printed Circuit Board (MCPCB) or a strip of a flexible circuit board, and a multi-LED package light-emitting device 1650 mounted on and connected to the substrate. As shown, the color-tunable multi-LED package light-emitting device 1650 can be arranged in a linear array along the elongation of the substrate. For illustrative purposes only, the color-tunable multi-LED package light-emitting device 1650 is shown to comprise the device of FIGS. 13A-13C, comprising a PC red LED (R), a green LED (G), a blue LED (B), and a white LED (W). It will be apparent that the device 1650 can comprise other color-tunable multi-LED package light-emitting devices described herein. Each LED of a given color may be electrically connected in series, with anode electrical connectors 1672R, 1672G, 1672B, and 1672W and cathode electrical connectors 1674R, 1674G, 1674B, and 1674W at opposite ends of the substrate for each string of LEDs.

[0111] Test data for practical use In this specification, Pack# is used to represent the color-tunable multi-LED package light-emitting device according to the present invention.

[0112] A color-tunable multi-LED package light-emitting device designated Pack 1 includes the device of FIGS. 13A-13C and includes a PC red LED, a PC green LED, a blue LED, and a PC white LED. The PC red LED in the first cavity includes a single layer structure, which is made of KSF (K2SiF6:Mn 4+ ) narrowband red fluoride phosphor and CASN(Ca 1-x Sr xThe LED in the second cavity is comprised of a PC green LED, which comprises a blue-violet-blue InGaN LED chip and a green silicate phosphor. The green phosphor ((Ba,Sr)2SiO4) is comprised of a phenyl silicone, and the mixture is dispensed into the second cavity of the package to completely cover the blue-violet-blue InGaN LED chip. The blue LED in the third cavity is comprised of an InGaN blue LED chip. The white LED in the fourth cavity is comprised of a single layer PC white LED, which comprises a green-red photoluminescent material (e.g., (Ba,Sr)2SiO4 and CASN). The green-red phosphor is contained in a phenyl silicone, and this mixture is dispensed into the fourth cavity of the package to cover the violet-blue InGaN LED chip.

[0113] The color-tunable multi-LED package light-emitting device of the present invention includes four individual LEDs (red, green, blue, and white) and uses four independent currents to drive the individual LEDs. In generating white light of different CCTs, the light generated by the white LEDs can be combined with light from red LEDs and / or green LEDs and / or blue LEDs in different ratios to generate light of any CIE white color point on the blackbody locus, which preferably meets ANSI lighting standards. In contrast, current smart lighting products use one cool white (CW) LED and one warm white (WW) LED, and do not mix light from RGB LEDs. Such smart lighting products can tune the CIE white color point along the straight line connecting the CIE CW color point to the CIE WW color point; for example, they can tune the CCT from 2700K (WW) to 6500K (CW). For CIE points between the CIE CW color point and the CIE WW color point, especially those that are midway between the CCT color points of approximately 4000 K, the CIE color points deviate significantly from the black body locus. As a result, current smart lighting products are unable to generate light with a CIE white color point that is on the black body locus throughout their color temperature operating range and struggle to meet ANSI lighting standards.

[0114] Table 4 lists the measured optical characteristics of the PC red LED (R), PC green LED (G), blue LED (B), and white LED (W) in the color-tunable multi-LED package light-emitting device pack 1. As can be seen from Table 4, the PC red LED has a dominant wavelength (λ d The PC green LED produces red light with a dominant wavelength of 547 nm and a color purity of 90%, the PC green LED produces light with a dominant wavelength of 547 nm and a color purity of 80%, and the blue LED produces light with a dominant wavelength of 467 nm and a color purity of 99%. The white LED produces warm white (WW) light with a CCT of 3000K and an average color rendering index (CRI Ra) of 70. For comparison, the light produced by the white LED has a dominant wavelength of 585 nm and a color purity of 52%.

[0115] [Table 4]

[0116] 17A-17C are measured optical characteristics of a color-tunable multi-LED packaged light-emitting device (Pack 1), where FIG. 17A shows the spectra, i.e., normalized intensity (arbitrary units) versus wavelength (nm), for the PC Red LED (thick solid line), PC Green LED (dash-dotted line), Blue LED (dotted line), and White LED (dashed line); FIG. 17B is a CIE 1931 chromaticity diagram illustrating the chromaticity (color points), ANSI CCT center points (solid circles), device gamuts (solid lines), and blackbody locus (dashed lines) of the light generated by the PC Red LED (squares), PC Green LED (diamonds), Blue LED (triangles), and White LED (crosses); and FIG. 17C is a CIE 1931 chromaticity diagram illustrating the calculated color purity of the light generated by the PC Red LED, PC Green LED, Blue LED, and White LED.

[0117] Referring to Figure 17A, the PC Red LED shows a low intensity blue peak 1747 at about 449 nm, corresponding to a small amount of "blue light pass". The CIE chromaticity diagram in Figure 17B shows the chromaticity (color point) 1776 (square) of red light produced by the PC Red LED, the chromaticity (color point) 1778 (diamond) of green light produced by the PC Green LED, the chromaticity (color point) 1780 (triangle) of blue light produced by the Blue LED, and the chromaticity (color point) 1782 (cross) of light produced by the White LED. The lines 1784 connecting points 1776, 1778, and 1780 define a triangle representing the color / color temperature (chromaticity) of light that the light emitting device pack 1 can produce - i.e., the device can produce light of any color / color temperature that lies on or within the triangle. It should be noted that the lowest CCT on the blackbody locus (dashed line) of light that the device can generate is approximately 2240K, which corresponds to the intersection 1786 of the line 1784 connecting color points 1776 and 1778 with the blackbody locus.

[0118] The CIE chromaticity diagram in Figure 17C illustrates the calculated chromaticity of light produced by a PC Red LED, a PC Green LED, a Blue LED, and a White LED. As explained herein, chromaticity, or saturation, is the degree to which the hue of light of a given color (chromaticity) is expressed as a function of the dominant wavelength λ. d 17C, the chromaticities (color points) 1776, 1778, 1780, and 1782 of the PC Red LED, PC Green LED, Blue LED, and White LED are indicated on the chromaticity diagram by crosses, and the "White Standard Illuminant", CIE (1 / 3, 1 / 3), is indicated by point 1736. Respective straight lines 1738R, 1738G, 1738B, 1738W connecting each color point 1776, 1778, 1780, and 1782 to the "White Standard Illuminant" 1736 are extended to intersect the outer curved boundary of the CIE color space. The intersection point 1740 closest to a given color point is the dominant wavelength λ of that color as the wavelength of the pure spectral color (monochromatic) at that intersection point. d The color purity of light of a given chromaticity plotted on a chromaticity diagram is determined by the "white standard illuminant" 1736, which is the dominant wavelength λ d The ratio of the distance from the "white standard illuminant" 1736 to the color points 1776, 1778, 1780, and 1782 to the distance to the intersection point 1740 corresponding to the color purity and dominant wavelength is tabulated in Table 4.

[0119] Table 5 shows the forward current (I F) for nominal color temperatures (CCT) of 2700K, 3000K, 4000K, 5000K, and 6500K. Table 6 lists the measured optical and electrical properties of Device Pack 1 for nominal color temperatures from 2700K to 6500K when operated to produce light with a nominal CRI Ra of 90. As can be seen from Table 5, the CCT of the light produced by Device Pack 1 is increased by a combination of: (i) increasing the blue light component produced by the blue LED, (ii) increasing the green light component produced by the PC green LED, (iii) decreasing the red light component produced by the PC red LED, and (iv) decreasing the white light produced by the white LED. Table 6 illustrates that by selecting the drive currents of the PC Red LED, PC Green LED, Blue LED, and White LED, the color-tunable multi-LED packaged light emitting device (Pack 1) can generate white light having a CCT of 2700K to 6500K, an average color rendering index CRI Ra of 90, and a CRI R9 of at least 50, with a luminous efficacy of about 114 to about 124 lm / W. Table 5 also includes measurements of the CCT of the light generated by Pack 1.

[0120] [Table 5]

[0121] [Table 6]

[0122] 18A-18C are measured emission characteristics of a color-tunable multi-LED packaged light emitting device (Pack 1) operable to generate light having a CCT of 2700K to 6500K and a CRIRa of 90, where FIG. 18A shows the spectrum, i.e., normalized emission intensity (arbitrary units) versus wavelength (nm), for a CCT of 2700K (dotted line), a CCT of 3000K (dashed line), and a CCT of 400K (solid line), and FIG. 18B shows the spectrum, i.e., normalized emission intensity (arbitrary units) versus wavelength (nm). FIG. 18C shows the chromaticity (color point) of the light generated by the color-tunable multi-LED packaged light emitting device (Pack 1) for nominal CCTs of 2700K, 3000K, 4000K, 5000K, 5700K, and 6500K, with the emission locus (solid line), blackbody locus (dashed line), and MacAdam ellipse for nominal CCTs from 2700K to 6500K.

[0123] As described herein, the CCT of the light generated by the device pack 1 is increased by a combination of: (i) increasing the blue light component generated by the blue LED, (ii) increasing the green light component generated by the PC green LED, (iii) decreasing the red light component generated by the PC red LED, and (iv) decreasing the white light component generated by the white LED. As can be seen from the spectra in Figures 18A and 18B, the CCT of the light generated by the device pack 1 is increased by a combination of: (i) increasing the blue light component generated by the blue LED, as shown by arrow 1888, (ii) increasing the green light component generated by the PC green LED, as shown by arrow 1890, and (iii) decreasing the red light component generated by the PC red LED, as shown by arrow 1892.

[0124] Referring to FIG. 18C, one notices that the emission locus (solid line 1894) - the chromaticity of light that pack 1 can produce - is a curve that closely follows the blackbody locus (dashed line). As explained herein, Δuv (delta uv) is a metric that quantifies how close a given color temperature is to the blackbody locus. Table 6 lists the Δuv for device pack 1 operating to produce light with a nominal CRI Ra of 90 for nominal CCTs of 2700K, 3000K, 4000K, 5000K, and 6500K. As can be seen from the table, Δuv varies from -0.0003 to 0.0031.

[0125] Table 7 shows the driving current (I F ) for nominal color temperatures (CCT) of 2700K, 3000K, 4000K, 5000K, 5700K, and 6500K. Table 8 lists the optical and electrical characteristics of Device Pack 1 when operated to produce a nominal CRI Ra of 95.

[0126] As can be seen from Table 7, the CCT of the light generated by device Pack 1 is increased by a combination of: (i) increasing the blue light component generated by the blue LED, (ii) increasing the green light component generated by the PC Green LED, (iii) decreasing the red light component generated by the PC Red LED, and (iv) decreasing the white light generated by the white LED. Table 8 illustrates that by selecting the drive currents of the PC Red LED, PC Green LED, Blue LED, and White LED, the color-tunable multi-LED package light-emitting device (Pack 1) can generate light having a CCT from 2700K to 6500K, an average color rendering index CRI Ra of 95, and a CRI R9 of at least 80, with a luminous efficacy of about 110 to about 115 lm / W.

[0127] [Table 7]

[0128] [Table 8]

[0129] Figure 19 is a CIE 1931 chromaticity diagram illustrating measurements of the chromaticity (color point) of light produced by a color-tunable multi-LED packaged light-emitting device (Pack 1) operable to produce light having a CRI Ra of 95 for nominal color temperatures of 2700K, 3000K, 4000K, 5000K, and 6500K. The diagram also shows the emission locus (solid line), the blackbody locus (dashed line), and the MacAdam ellipse for CCTs from 2700K to 6500K. Referring to Figure 20, it is noted that the emission locus (solid line 1994) - the chromaticity locus of light that Pack 1 can produce - is a curve that closely follows the blackbody locus (dashed line). Table 8 lists the Δuv values ​​for Device Pack 1, operated to produce light having a nominal CRI of 95, for nominal CCTs of 2700K, 3000K, 4000K, 5000K, 5700K, and 6500K. As can be seen, the Δuv values ​​vary from -0.0002 to 0.0023.

[0130] In view of the above, the color-tunable multi-LED package light-emitting device according to an embodiment of the present invention can generate white light with different CCT and different CRI Ra (e.g., CRI Ra90 and CRI Ra95) by varying the forward driving current of the four LEDs (i.e., red, green, blue, and white). Furthermore, the device according to the present invention has a higher luminous efficiency compared to current color-tunable multi-LED package light-emitting devices. The combination of these features represents a significant breakthrough in the lighting industry, significantly reducing the SKUs (Stock Keeping Units) of LED packages required for different lighting applications.

[0131] As described herein, the multi-cavity LED package may have a pair of respective anode and cathode electrical terminals connected to each cavity. In other embodiments of the present invention, the LED package may include a common cathode terminal connected to each cavity and a respective anode terminal connected to each cavity. FIG. 20A is a schematic representation of a four-cavity LED package according to an embodiment of the present invention, and FIG. 20B is a schematic representation of a lead frame of the four-cavity LED package of FIG. 20A. As shown in FIGS. 20A and 20B, the LED package 2014 includes lead frames 2012a-2012e and a housing 2016 molded on the lead frames. The housing 2016 includes a first cavity 2020a, a second cavity 2020b, a third cavity 2020c, and a fourth cavity 2020d - shown as dashed rectangles in FIG. 20A - for receiving respective LED chips. As shown, the package 2014 includes a first anode electrical terminal 2022a connected to the first cavity 2020a, a second anode electrical terminal 2022b connected to the second cavity 2020b, a third anode electrical terminal 2022c connected to the third cavity 2020c, and a fourth anode electrical terminal 2022d connected to the fourth cavity 2020d, and a common cathode electrical terminal 2024 connected to each of the cavities 2020a, 2020b, 2020c, and 2020d, allowing for independent power supply to each LED chip 2026. Referring to FIG. 20B, areas of the leadframes 2012a-2012e are indicated by cross-hatching, the housing 2016 is indicated by dashed lines, and the cavities 2020a-2020e are indicated by dotted lines. The leadframe comprises a central cross-shaped region 2012e and four rectangular regions 2012a, 2012b, 2012c, and 2012d located at the free corners of the cross-shaped region 2012e. As can be seen in this figure, each cavity 2020a, 2020b, 2020c, and 2020d has a respective L-shaped region of the cross-shaped region 2012e that constitutes a common cathode connection to each cavity.Rectangular regions 2012a, 2012b, 2012c, and 2012d constitute the anode connections to the respective cavities. As can be seen in Fig. 20A, the L-shaped regions, in addition to providing a common cathode connection, provide thermally conductive mounting pads for the LED chip 2026, thereby improving heat dissipation from the LED chip 2026. [Explanation of symbols]

[0132] List of reference numbers Figure 1 1 Multi-LED package 2 Lead Frame 3. Direct-emitting LED chips 3R direct emission red LED chip 3G direct emission green LED chip 3B direct emission blue LED chip 4. Housing 5 Cavity (recess) 6 Translucent encapsulant 7 Anode electrical terminal 7R Anode Electrical Terminal Red LED 7G Anode electrical terminal Green LED 7B Anode electrical terminal Blue LED 8 Cathode electrical terminal 8R Cathode Electrical Terminal Red LED 8G Cathode electrical terminal Green LED 8B Cathode electrical terminal Blue LED Figures 2-20 (#=figure number) #10 Red light emitting device #12 Lead frame #14 Housing (package) #16 Bottom of housing #18A Housing side wall #18B Housing side wall #20 Cavity (recess) #20a First cavity (first recess) #20b Second cavity (second recess) #20c 3rd cavity (3rd recess) #20d 4th cavity (4th recess) #22 Anode electrical terminal #22a Anode electrical terminal first cavity (recess) #22b Anode electrical terminal second cavity (recess) #22c Anode electrical terminal 3rd cavity (recess) #22d Anode electrical terminal 4th cavity (recess) #24 Cathode electrical terminal #24a Cathode electrical terminal first cavity (recess) #24b Cathode electrical terminal second cavity (recess) #24c Cathode electrical terminal 3rd cavity (recess) #24d Cathode electrical terminal 4th cavity (recess) #26 Blue-purple to blue LED chip #28 Bond wire #30 Red photoluminescent layer #30A 1st Red Photoluminescent Layer #30B 2nd Red Photoluminescent Layer #32 Light reflective layer #34 Chromaticity (color point) #36 White Standard Illuminant CIE (1 / 3, 1 / 3) #38 Straight line #40 Main wavelength λ d #42 Complementary color dominant wavelength λ c #44 Blue Peak #46 Blue Peak - Single Layer PC Red LED #48 Blue Peak - Dual Layer PC Red LED #50 Color-tunable multi-LED package light-emitting device #52 Housing #54 Green LED #56 Blue LED #57R Chromaticity (color point) - Red LED #57G Chromaticity (Color Point)-Green LED #57B Chromaticity (color point) - Blue LED #57W Chromaticity (color point) - White LED #57CW Chromaticity (color point) - Cool white (CW) LED #57WW Chromaticity (color point) - Warm white (WW) LED #58 Straight line connecting chromaticity (color points) #59 White LED #60 Green photoluminescent layer #62 Green to red photoluminescent layer #64 CW (Cool White) LED #66a 1st LED #66b 2nd LED #66c 3rd LED #66d 4th LED #68 Color-tunable linear light-emitting device #70 Circuit Board #72 Anode electrical terminal #74 Cathode electrical terminal #76 Chromaticity (Color Point) - Red PC LED (Pack 1) #78 Chromaticity (Color Point) - Green PC LED (Pack 1) #80 Chromaticity (color point) - Blue PC LED (Pack 1) #82 Chromaticity (color point) - White PC LED (Pack 1) #84 Straight line connecting chromaticity (color points) #86 Minimum CCT Chromaticity (Color Point) #88 Arrows - Blue region of the spectrum #90 Arrows - Green region of the spectrum #92 Arrows - Red region of the spectrum #94 Luminous Trail #96 Highest CCT chromaticity (color point)

Claims

1. 1. A light emitting device comprising a phosphor-converted red LED, the phosphor-converted red LED comprising: A blue LED; A photoluminescent material including a narrowband red fluoride phosphor and a broadband red phosphor. A light emitting device comprising:

2. The narrow band red phosphor is K 2 SiF 6 ;Mn 4+ , K 2 GeF 6 ;Mn 4+ , and K 2 TiF 6 :Mn 4+ 10. The light emitting device of claim 1, wherein the at least one narrow band red phosphor is selected from the group consisting of

3. 3. The light emitting device of claim 1, comprising a package having at least one cavity for the phosphor-converted red LED.

4. 3. The light emitting device of claim 1, wherein the blue LED comprises a flip chip, and the narrowband red fluoride phosphor and the broadband red phosphor are on a light emitting surface of the flip chip.

5. 3. The light emitting device of claim 1 or 2, wherein the narrowband red fluoride phosphor and the broadband red phosphor are in one layer, optionally in a single layer.

6. 3. The light emitting device of claim 1, wherein the narrowband red fluoride phosphor is in a first layer and the broadband red phosphor is in a second layer.

7. The broadband red phosphor has the general composition CaAlSiN 3 :EU 2+ Nitride phosphor with general composition (Sr,Ca)AlSiN 3 :EU 2+ Nitride phosphor, general composition (Sr,Ba) 2 AlSi 5 N 8 :EU 2+ Nitride phosphor with general composition MSe 1-x S x A group IIA / IIB sulfide selenide phosphor of formula (IIA / IIB):Eu, where M is one of Mg, Ca, Sr, Ba, and Zn, and 0<x<1.0, and the general composition (Sr 1-x M x ) y EU z SiO 5 3. The light emitting device according to claim 1, wherein 0<x≦0.5, 2.6≦y≦3.3, 0.001≦z≦0.5, and M is at least one divalent metal selected from the group consisting of Ba, Mg, Ca, and Zn.

8. 3. The light emitting device of claim 1, wherein the phosphor-converted red LED produces red light having a color purity of at least 90%.

9. The light-emitting device of claim 1, wherein the phosphor-converted red LED generates red light having a FWHM of less than 30 nm, less than 20 nm, or less than 10 nm.

10. The light-emitting device of claim 1 or 2, wherein the phosphor-converted red LED generates red light having a peak emission wavelength from 620 nm to 640 nm.

11. 3. The light emitting device of claim 1, further comprising a green LED and a direct emitting blue LED.

12. 12. The light emitting device of claim 11, wherein the green LED comprises a direct-emitting green LED.

13. 12. The light emitting device of claim 11, wherein the green LED is a phosphor-converted green LED, the phosphor-converted green LED comprising a violet-to-blue LED flip chip and a green phosphor.

14. 12. The light emitting device of claim 11, wherein the green LED is comprised of a chip-scale packaged phosphor-converted green LED comprising a violet-to-blue LED flip chip and a green phosphor on an emitting surface of the violet-to-blue LED flip chip.

15. 12. The light emitting device of claim 11, comprising a package having at least one cavity for the green LED.

16. 15. The light emitting device of claim 14, comprising a package having at least one cavity for the green LED.

17. 12. The light emitting device of claim 11, comprising a package having at least one cavity for the direct-emitting blue LED.

18. 3. A light emitting device according to claim 1, comprising a fourth LED generating light having a CCT of at least 1800K.

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