Light concentrator for light mixing in light-emitting diode packages

Abstract

Disclosed are light-emitting diode (LED) packages, particularly a focuser for mixing light in an LED package to improve the far-field emission pattern (FFP) of the LED package. The LED package may include one or more LED chips having different wavelength ranges, and the focuser positioned above the LED chips may have a reflective surface in addition to a reduced aperture from which light from the LED chips is emitted after being mixed within the focuser. The LED package may also include a lens to further improve the FFP. In embodiments, the focuser may include a diffusing material to facilitate the mixing of light within the focuser. An LED package with a focuser significantly improves the FFP of multicolor LED chips in the LED package by mixing multiple light-emitting point sources into a single point source or a reduced area source.

Description

[Technical Field] 【0001】 (Related applications)

[0001] This application claims the interests of U.S. Patent Application No. 18 / 207,399, filed on 8 June 2023, and U.S. Patent Application No. 18 / 656,839, filed on 7 May 2024, the disclosures of which are incorporated herein by reference in their entirety. 【0002】 (Area of ​​disclosure)

[0001] This disclosure relates to a light-emitting diode (LED) package, and more particularly to a light collector for mixing light in an LED package. [Background technology] 【0003】

[0002] Solid-state lighting devices such as light-emitting diodes (LEDs) are increasingly used in both consumer and commercial applications. Advances in LED technology have resulted in highly efficient, mechanically robust, and long-lasting light sources. Consequently, modern LEDs enable a variety of new display applications and are increasingly being used in general lighting applications, often replacing incandescent and fluorescent light sources. 【0004】

[0003] An LED is a solid-state device that converts electrical energy into light and generally includes an active layer (or active region) of one or more semiconductor materials positioned between an inversely doped n-type layer and a p-type layer. When a bias is applied to the entire doped layer, holes and electrons are injected into one or more active layers, where they recombine to produce light such as visible light or ultraviolet light. An LED chip typically includes an active region, which may be made from, for example, gallium nitride, gallium phosphide, aluminum nitride, indium nitride, gallium indium-based materials, gallium arsenide-based materials, and / or organic semiconductor materials. Photons generated by the active region are emitted in all directions. 【0005】

[0004] LED packages have been developed that can provide mechanical support, electrical connections, and encapsulation for LED emitters. Lumiphoric materials, such as phosphors, can also be placed near the LED emitter to convert some of the light emission to different wavelengths. LED technology continues to be developed for ever-evolving modern applications, but addressing the operational requirements of LED packages and related components of LED packages remains a challenge. 【0006】

[0005] LED packages containing multiple LED chips, especially those with LED chips of different colors, can produce far-field patterns (FFPs) where the intensity of the color varies depending on the viewing angle of the LED package. Because the color is observed to change depending on the viewing angle, this can negatively affect the color uniformity of LED displays and other applications. 【0007】

[0006] The technical field continues to seek improved LED and solid-state lighting devices that have desirable lighting characteristics and can overcome the challenges associated with conventional lighting devices. [Overview of the project] [Means for solving the problem] 【0008】 【0007】This disclosure relates to a light-emitting diode (LED) package, and more particularly, to a condenser for mixing light in an LED package to improve the far-field pattern (FFP) of the LED package. The LED package can be composed of one or more LED chips having different wavelength ranges, and the condenser disposed on the LED chip can have a reflective surface in addition to a reduced aperture from which light is emitted from the LED chip after being mixed in the condenser. The LED package can also include a lens for further adjusting the FFP. In an embodiment, the condenser includes a diffuser material and can facilitate the mixing of light within the condenser. An LED package having a condenser mixes a plurality of emission point sources into a single point source or a reduced-area source, significantly improving the FFP of the multi-color LED chips of the LED package. 【0009】 【0008】In an embodiment, the LED package includes one or more LED chips and at least one condenser disposed above the one or more LED chips, the condenser being formed from a first light-transmissive material, and at least one reflective coating on the surface of the condenser, the reflective coating forming at least one opening. 【0010】 【0009】In an embodiment, the opening of the condenser is at the upper part of the stem portion of the condenser. 【0010】In an embodiment, the first width of the stem portion and the opening is less than 10% of the second width of the housing. 【0011】 【0011】In an embodiment, the width of the opening is at least 50 μm. 【0012】 In an embodiment, the height of the stem portion is such that at least a part of the light emitted by at least one of the one or more LED chips is reflected at least once on at least one surface before exiting the opening. 【0012】 【0013】 In an embodiment, there is no direct line of sight between the opening and most of at least one of the one or more LED chips. 【0013】 【0014】 In an embodiment, a lens having a curved surface is at least partially fixed above the condenser. 【0015】 In an embodiment, the LED package further includes a fill layer surrounding the condenser that blocks stray light from the condenser. 【0014】 【0016】 In an embodiment, the LED package further includes a masking layer on the fill layer. 【0017】 In an embodiment, the condenser includes a diffusing material that diffuses the light emitted by one or more LED chips. 【0015】 【0018】 In an embodiment, the upper surface of the condenser is at least one of curved or linear, and the stem portion is at the apex of the condenser. 【0019】 In an embodiment, the reflective coating includes at least one of a metal or a metal oxide. 【0016】 【0020】 In an embodiment, the far-field pattern of the light emitted by each LED chip of the plurality of chips has a maximum delta theta of less than two degrees. 【0021】 In an embodiment, the first light transmissive material is an epoxy or silicone. 【0017】 【0022】 In the embodiment, the LED package may further include a housing that forms a recess having a recess floor and one or more recess sidewalls, in which one or more LED chips are disposed within the recess, and a lead frame structure that extends through the housing, with a portion of which is disposed along the recess floor.

[0018] 【0023】 In another embodiment, the LED package may include one or more LED chips and at least one light-gathering device positioned at least partially above the one or more LED chips, wherein the light-gathering device has a columnar protrusion and is formed from a first light-transmitting material.

[0019] 【0024】 In this embodiment, the first width of the columnar projection is in the range of 25% to 250% of the lateral dimension of one of the LED chips among the one or more LED chips. 【0025】 In this embodiment, there is no direct line of sight between at least 50% of the upper surface of one of the LED chips and the aperture of the light condenser.

[0020] 【0026】 In this embodiment, the light concentrator includes a diffusing material that diffuses the light emitted by one or more LED chips. 【0027】 In this embodiment, the far-field pattern of the light emitted by each LED chip among the multiple chips has a maximum delta theta of less than 2 degrees.

[0021] 【0028】 In the embodiment, the LED package further includes a housing that forms a recess having a recessed bottom and one or more recessed sidewalls, and a lead frame structure that extends through the housing, with a portion of it positioned along the recessed bottom.

[0022] 【0029】 In the embodiment, the LED package further includes a reflective coating that covers the entire outer surface of the concentrator, except for the reduced opening at the top of the columnar projection. 【0030】 In the embodiment, the LED package further includes a lens that at least partially covers the light concentrator.

[0023] 【0031】 In another embodiment, the LED package includes a housing that forms a recess having a recessed bottom and one or more recessed sidewalls, and a lead frame structure that extends through the housing, with a portion of it positioned along the recessed bottom. The LED package may also include one or more LED chips disposed within the recess and electrically coupled to the lead frame structure, a light condenser that is at least partially disposed within the recess and above the one or more LED chips, and is formed from a first light-transmitting material, a reflective coating on the surface of the light condenser that forms an opening at the apex of the light condenser, and a lens having a curved surface fixed above at least a portion of the light condenser.

[0024] 【0032】 In another embodiment, the LED display may include a display panel and at least one LED package, the at least one LED package comprising one or more LED chips and at least one condenser positioned above the one or more LED chips, the condenser being formed from a first light-transmitting material, and at least one reflective coating on the surface of the condenser, the reflective coating forming at least one opening.

[0025] 【0033】 In this embodiment, a lens having a curved surface is fixed above at least a portion of the light condenser. 【0034】 In this embodiment, the far-field pattern of the light emitted by each LED chip among the multiple chips has a maximum delta theta of less than 2 degrees.

[0026] 【0035】 In this embodiment, one or more LED chips are multiple LED chips composed of a combination of red, green, and blue LED chips. 【0036】 In another embodiment, the LED package comprises at least three LED chips configured to produce a plurality of peak wavelengths, at least one focuser positioned above the at least three LED chips and formed from a first light-transmitting material, and at least one reflective coating on the surface of the focuser, the reflective coating forming an aperture. In a particular embodiment, the far-field pattern of aggregate emission from the at least three LED chips has a full width at half maximum of less than 50.

[0027] 【0037】 In certain embodiments, the figure of merit (FOM) of the far-field pattern is in the range of 0.7 to 0.995, where FOM defines a color quality index relating to the uniformity of the far-field pattern with respect to the central peak wavelength among multiple peak wavelengths, and FOM is a function of the raw far-field pattern data of each LED chip, the noise-corrected luminous intensity data of the raw far-field pattern data of each LED chip, the percentage difference of all non-zero noise-corrected luminous intensity data with respect to the center, the area under the curve for all absolute values ​​of the percentage difference with respect to the central peak wavelength, and the ratio of the area under the curve for all possible values ​​normalized from minimum to maximum from 0 to 1, a ratio normalized based on a minimum criterion of 0.6. In certain embodiments, FOM is in the range of 0.9 to 0.995.

[0028] 【0038】In other embodiments, additional advantages can be obtained by combining any of the embodiments described herein individually or together, and / or by combining the various individual embodiments and features described herein. Any of the various features and elements disclosed herein may be combined with one or more other disclosed features and elements unless otherwise indicated herein.

[0029] 【0039】 Those skilled in the art will understand the scope of this disclosure and its additional embodiments after reading the following detailed description of preferred embodiments in conjunction with the accompanying drawings. 【0040】 The accompanying drawings incorporated herein and forming part of herein illustrate several aspects of this disclosure and, together with the description, are useful in illustrating the principles of this disclosure. [Brief explanation of the drawing]

[0030] [Figure 1] 【0041】 This is a top view of a light-emitting diode (LED) package according to an embodiment of the present disclosure, which includes a lead frame structure collectively formed by a plurality of leads, a body or housing enclosing a portion of the lead frame structure, and a first sealing layer disposed within a recess formed by the housing. [Figure 2] 【0042】 This is a cross-sectional view of the LED package shown in Figure 1, according to an embodiment of the present disclosure. [Figure 3] 【0043】 This is a cross-sectional view of an LED package having a different shaped concentrator according to an embodiment of the present disclosure. [Figure 4] 【0044】 This is a cross-sectional view of an LED package having a light condenser and a lens according to an embodiment of the present disclosure. [Figure 5] 【0045】 This is a cross-sectional view of an LED package similar to the one shown in Figure 4, having a different shaped concentrator, according to an embodiment of the present invention. [Figure 6] 【0046】These are cross-sectional views of LED packages similar to those shown in Figures 4 and 5, having differently shaped concentrators, according to embodiments of the present disclosure. [Figure 7] 【0047】 This is a cross-sectional view of an LED package similar to the one shown in Figure 5, having a light concentrator with a diffusing material, according to an embodiment of the present invention. [Figure 8] 【0048】 This is a cross-sectional view of an LED package similar to the one shown in Figure 6, having a light concentrator with a diffusing material, according to an embodiment of the present invention. [Figure 9] 【0049】 This is a diagram of a light concentrator according to an embodiment of the present disclosure. [Figure 10] 【0050】 This is another cross-sectional view of an LED package having a light concentrator and a filler material, according to an embodiment of the present disclosure. [Figure 11] 【0051】 This is a perspective view of an LED package having a light condenser and a filler material according to an embodiment of the present disclosure. [Figure 12] 【0052】 This is a perspective view of an LED package having a lens according to an embodiment of the present invention. [Figure 13] 【0053】 In the far-field pattern (FFP) graphs shown in Figures 14A-14B and 15A-15B, the light intensity is plotted on the axis as a function of the viewing angle, representing the LED package. [Figure 14A] 【0054】 This is a graph of FFP for conventional LED packages. [Figure 14B] This is a graph of FFP for conventional LED packages. [Figure 15A] 【0055】 This is a graph of the FFP of an LED package disclosed herein in accordance with embodiments of this disclosure. [Figure 15B] This is a graph of the FFP of an LED package disclosed herein in accordance with embodiments of this disclosure. [Figure 16A] 【0056】This is another representation of the FFP of the LED package disclosed herein, compared to a conventional LED package, in accordance with embodiments of the present disclosure. [Figure 16B] This is another representation of the FFP of the LED package disclosed herein, compared to a conventional LED package, in accordance with embodiments of the present disclosure. [Figure 17A] 【0057】 This is a representation of an FFP (Fiber Focused Packet) LED package that includes a lens but does not include a light-gathering element. [Figure 17B] This is a representation of an FFP (Fiber Focused Packet) LED package that includes a lens but does not include a light-gathering element. [Figure 18A] 【0058】 This is another representation of the FFP of the lensed LED package disclosed herein, compared to a lensed RGB component without a light concentrator, according to embodiments of the present disclosure. [Figure 18B] This is another representation of the FFP of the lensed LED package disclosed herein, compared to a lensed RGB component without a light concentrator, according to embodiments of the present disclosure. [Figure 19] 【0059】 This is a top view of the front of a typical display screen according to an embodiment of the present disclosure. [Figure 20A] 【0060】 This graph shows an exemplary far-field pattern in the VV direction of an exemplary LED package, as well as the reference total envelope full width at half maximum (TEFWHMREF) for the total light emitted from the LED chip. [Figure 20B] 【0061】 Figure 20A shows an exemplary far-field pattern in the HH direction of an LED package, as well as a graph showing the TEFWHMREF for the total light emitted from the LED chip. [Figure 21A] 【0062】 This is a graph of the VV-direction far-field pattern in raw data format for an LED package without a focuser and filler material, similar to the LED package in Figure 12. [Figure 21B] 【0063】Figure 21A shows a graph of the raw data format of the far-field pattern in the HH direction for the LED package. [Figure 21C] 【0064】 This graph shows the data from Figure 21A, with the noise-corrected far-field pattern (NC FFP) in the VV direction added. [Figure 21D] 【0065】 This graph shows the data from Figure 21C, with the noise-corrected far-field pattern (NC FFP) in the HH direction added. [Figure 21E] 【0066】 Figure 21C is a graph showing the delta from the center of the plotted line, using the TEFWHM value normalized in the VV direction. [Figure 21F] 【0067】 Figure 21D is a graph showing the delta from the center of the plotted line, using the TEFWHM normalized in the HH direction, i.e., IvNC%(θ) based on the TEFWHM value. [Figure 21G] 【0068】 This graph shows the absolute values ​​of the plotted lines in Figure 21E. [Figure 21H] 【0069】 This graph shows the absolute values ​​of the plotted lines in Figure 21F. [Figure 22] 【0070】 This is a summary table showing the performance index (FOM) that defines the red-green-blue color quality index metric for various LED package configurations. [Modes for carrying out the invention]

[0031] 【0071】 The embodiments described below provide the information necessary to enable those skilled in the art to implement the embodiments and represent the best mode of implementation. By reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and recognize applications of these concepts not specifically addressed herein. It should be understood that these concepts and applications are included within the scope of this disclosure and the accompanying claims.

[0032] 【0072】 In this specification, terms such as "First," "Second," etc., may be used to describe various elements, but it will be understood that these elements should not be limited by these terms. These terms are used solely to distinguish one element from another. For example, without departing from the scope of this disclosure, the First element may be referred to as the Second element, and similarly, the Second element may be referred to as the First element. As used herein, the terms "and / or" include one or more of the related enumerated items, and all combinations thereof.

[0033] 【0073】 When an element such as a layer, region, or substrate is described as being "on top of" or "extending above" another element, it will be understood that the element may be directly above or extending directly above the other element, or there may be an intervening element. In contrast, when an element is described as being "directly above" or extending directly above another element, there is no intervening element. Similarly, when an element such as a layer, region, or substrate is described as being "above" or "extending above" another element, it will be understood that the element may be directly above or extending directly above the other element, or there may be an intervening element. In contrast, when an element is described as being "directly above" or extending directly above another element, there is no intervening element. Also, when an element is described as being "connected" or "bonded" to another element, it will be understood that the element may be directly connected or bonded to the other element, or there may be an intervening element. In contrast, when an element is said to be "directly connected" or "directly coupled" to another element, there is no intervening element.

[0034] 【0074】Relative terms such as “down,” “up,” “above,” “downward,” “horizontal,” or “vertical” may be used herein to describe the relationship between one element, layer, or region and another, as illustrated in the figures. It will be understood that these terms and the terms discussed above are intended to encompass different orientations of the device, in addition to the orientation shown in the figures.

[0035] 【0075】 The terms used herein are intended solely to describe specific embodiments and are not intended to limit the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural form unless the context clearly indicates otherwise. Furthermore, the terms “equipped,” “equipped,” “contains,” and / or “contains” as used herein are understood to identify the presence of a described feature, complete, step, action, element, and / or component, but not to exclude the presence or addition of one or more other features, complete, step, action, element, component, and / or group thereof.

[0036] 【0076】 Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meanings as those generally understood by those skilled in the art to which this disclosure belongs. Furthermore, terms used herein should be construed as having meanings consistent with their meanings in the context of this specification and related art, and should not be construed in an idealized or overly formal sense unless expressly defined herein.

[0037] 【0077】Embodiments are described herein with reference to schematic drawings of embodiments of the present disclosure. Therefore, the actual dimensions of layers and elements may differ, and variations from the exemplary shapes are expected, for example, as a result of manufacturing techniques and / or tolerances. For example, areas illustrated or described as squares or rectangles may have rounded or curved features, and areas illustrated as straight lines may have some irregularities. Thus, the areas illustrated in the drawings are schematic, and their shapes are not intended to illustrate the exact shapes of areas in the device, nor are they intended to limit the scope of the disclosure. In addition, the size of structures or areas may be exaggerated in comparison to other structures or areas for illustrative purposes, and are therefore provided to illustrate general structures of the subject matter, and may or may not be drawn to scale. Elements common to both drawings may be indicated herein by common element numbers and may not be described again later.

[0038] 【0078】 This disclosure relates to light-emitting diode (LED) packages, and more particularly to a focuser for mixing light within the LED package to improve the far-field emission pattern (FFP) of the LED package. The LED package may consist of one or more LED chips having different wavelength ranges, and the focuser positioned above the LED chips may have a reflective surface in addition to a reduced aperture from which light from the LED chips is emitted after being mixed in the focuser. The LED package may also include a lens for further tuning the FFP. In embodiments, the focuser may include a diffusing material to facilitate the mixing of light within the focuser. An LED package having a focuser significantly improves the FFP of multicolor LED chips in the LED package by mixing multiple light-emitting point sources into a single point source or a reduced area source.

[0039] 【0079】Before delving into the specific details of various aspects of this disclosure, an overview of the various elements that may be included in an exemplary LED package of this disclosure is provided for context. An LED chip typically comprises an active LED structure or region which may have many different semiconductor layers arranged in different ways. The manufacturing and operation of LEDs and their active structures are generally known in the art and will be briefly discussed herein. The layers of an active LED structure can be manufactured using known processes which have a suitable process, such as manufacturing using metal-organic chemical vapor deposition. The layers of an active LED structure may comprise many different layers, and generally comprise an active layer sandwiched between n-type and p-type oppositely doped epitaxial layers, all of which are formed in a continuous manner on a growth substrate. The active LED structure is understood to include, but is not limited to, additional layers and elements such as buffer layers, nucleation layers, superlattice structures, undoped layers, cladding layers, contact layers, current-spreading layers, light extraction layers, and elements. The active layer may comprise a single quantum well, multiple quantum wells, a double heterostructure, or superlattice structures.

[0040] 【0080】Active LED structures can be manufactured from different material systems, some of which are Group III nitride-based. Group III nitrides are semiconductor compounds formed between nitrogen (N) and elements of Group III of the periodic table, typically aluminum (Al), gallium (Ga), and indium (In). Gallium nitride (GaN) is a common binary compound. Group III nitrides also refer to ternary and quaternary compounds such as aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AlInGaN). In the case of Group III nitrides, silicon (Si) is a common n-type dopant, and magnesium (Mg) is a common p-type dopant. Therefore, in the case of Group III nitride-based material systems, the active layer, n-type layer, and p-type layer may include one or more layers of GaN, AlGaN, InGaN, and AlInGaN, either undoped or doped with Si or Mg. Other material systems include organic semiconductor materials and other III-V group systems such as gallium phosphide (GaP), gallium arsenide (GaAs), and related compounds.

[0041] 【0081】 The active LED structure may be grown on a growth substrate that can contain many materials, including sapphire, SiC, silicon, aluminum nitride (AlN), and GaN. Sapphire is another common substrate for Group III nitrides and, among other related substrates, also has advantages such as low cost, established manufacturing processes, and excellent light-transmitting optical properties.

[0042] 【0082】Different embodiments of the active LED structure can emit light of different wavelengths depending on the composition of the active layer. In some embodiments, the active LED structure emits blue light with a peak wavelength range of about 430 nanometers (nm) to 480 nm. In other embodiments, the active LED structure emits green light with a peak wavelength range of 500 nm to 570 nm. In other embodiments, the active LED structure emits red light with a peak wavelength range of 600 nm to 700 nm. In certain embodiments, the active LED structure may be configured to emit light outside the visible spectrum, including one or more portions of the ultraviolet (UV) spectrum, one or more portions of the near-infrared spectrum, and / or the infrared spectrum (e.g., 700 nm to 1000 nm). The UV spectrum is typically divided into three wavelength range categories, indicated by the letters A, B, and C. Thus, UV-A light is typically defined as having a peak wavelength range of 315 nm to 400 nm, UV-B as typically having a peak wavelength range of 280 nm to 315 nm, and UV-C as typically having a peak wavelength range of 100 nm to 280 nm. UV LEDs are particularly important for use in applications related to the disinfection of microorganisms in air, water, and surfaces. For other applications, UV LEDs may be provided with one or more emissive materials to provide LED packages with aggregate emission having a broad spectrum and improved color quality for visible light applications.

[0043] 【0083】The LED chip may also be covered with one or more light-emitting materials (also referred to here as emitters), such as phosphors, so that at least a portion of the light from the LED chip is absorbed by one or more emitters and converted into one or more different wavelength spectra according to the characteristic emission from one or more emitters. In this regard, at least one emitter that receives at least a portion of the light produced by the LED light source can re-emit light having a different peak wavelength than the LED light source. The LED light source and one or more light-emitting materials may be selected so that the combined output has one or more desired properties such as color, color point, and intensity. In certain embodiments, the collective emission of the LED chip may optionally be combined with one or more light-emitting materials to provide cool white, neutral white, or warm white light, such as in a color temperature range of 2500 Kelvin (K) to 10,000 K. In certain embodiments, light-emitting materials having cyan, green, amber, yellow, orange, and / or red peak emission wavelengths may be used. In some embodiments, a combination of an LED chip and one or more light-emitting elements (e.g., phosphors) generally emits a combination of white light. One or more phosphors may be yellow (e.g., YAG:Ce), green (e.g., LuAg:Ce), and red (e.g., Ca i-x-y Sr x EU y This may include luminescent phosphors of AlSiN3, and combinations thereof.

[0044] 【0084】The luminescent materials described herein may be one or more of the following: phosphors, scintillators, luminescent inks, quantum dot materials, day glow tapes, etc., or may include them. The luminescent materials may be provided by any suitable means, such as direct coating on one or more surfaces of an LED, dispersion in a sealing material configured to cover one or more LEDs, and / or coating on one or more optical or support elements (e.g., by powder coating, inkjet printing, etc.). In certain embodiments, the luminescent materials may be down-converted or up-converted, and combinations of both down-converted and up-converted materials may be provided. In certain embodiments, several different (e.g., differently composed) luminescent materials arranged to produce different peak wavelengths may be arranged to receive light from one or more LED chips. One or more luminescent materials may be provided in various configurations on one or more parts of an LED chip. In certain embodiments, the luminescent material may be provided on one or more surfaces of an LED chip, while other surfaces of such an LED chip may not have any luminescent material.

[0045] 【0085】As used herein, a layer or region of an emitting device may be considered “transparent” if at least 80% of the light that strikes the layer or region passes through the layer or region and exits. Furthermore, as used herein, a layer or region of an LED is considered “reflective,” or embodies a “mirror” or “reflector,” if at least 80% of the light that strikes the layer or region is reflected. In some embodiments, the light emission comprises visible light, such as blue and / or green LEDs, with or without the emitting material. In other embodiments, the light emission may comprise invisible light. For example, in the case of GaN-based blue and / or green LEDs, silver (Ag) may be considered a reflective material (e.g., at least 80% reflectivity). In the case of UV LEDs, appropriate materials can be selected to achieve desired, in some embodiments, high reflectivity and / or, in some embodiments, low absorptivity. In certain embodiments, a “light-transmitting” material may be configured to transmit at least 50% of the light emission at the desired wavelength.

[0046] 【0086】This disclosure can be useful for LED chips having various geometries, such as vertical and transverse shapes. Vertical LED chips typically include an anode and a cathode on opposite sides or surfaces of the LED chip. Transverse LED chips typically include both an anode and a cathode on the same side of the LED chip opposite to a substrate, such as a growth substrate. In certain embodiments, a transverse LED chip is mounted on a submount of an LED package, with the anode and cathode on the surface of the LED chip opposite the submount. In this configuration, wire bonds can be used to provide electrical connections between the anode and cathode. In other embodiments, a transverse LED chip may be flip-chip mounted on the surface of a submount of an LED package, with the anode and cathode on the surface of an active LED structure adjacent to the submount. In this configuration, electrical traces or patterns can be provided on the submount to provide electrical connections between the anode and cathode of the LED chip. In a flip-chip configuration, the active LED structure is located between the LED chip substrate and the LED package submount. Therefore, light emitted from the active LED structure can pass through the substrate in the desired emission direction. In other embodiments, the active LED structure may be coupled to a carrier submount, eliminating the growth substrate and allowing light to exit the active LED structure without passing through the growth substrate.

[0047] 【0087】According to aspects of this disclosure, an LED package may include one or more elements such as a light-emitting material, a encapsulating material, a light-altering material, a lens, and electrical contacts, on which one or more LED chips are provided. In certain embodiments, the LED package may include a support material such as a submount or lead frame. Suitable materials for submounts include, but are not limited to, ceramic materials such as aluminum oxide, alumina, AlN, or organic insulators such as polyimide (PI) or polyphthalamide (PPA). In other embodiments, the submount may comprise a printed circuit board (PCB), sapphire, Si, or other suitable material. In the PCB embodiment, different PCB types may be used, such as a standard FR-4 PCB, a metal core PCB, or other types of PCBs. In even further embodiments, the support structure may embody a lead frame structure. A light-altering material may be placed within the LED package to reflect light from one or more LED chips or otherwise direct it to a desired emission direction or pattern.

[0048] 【0088】In certain embodiments, aspects of the present disclosure relate to LED packages having a lead frame structure at least partially housed by a body or housing. The lead frame structure may typically be formed of a metal such as copper, a copper alloy, or another conductive metal. The lead frame structure may initially be part of a larger metal structure that is individualized during the manufacture of individual LED packages. Within an individual LED package, the isolated portion of the lead frame structure can form connections between the anode and cathode of the LED chips. The body or housing may be formed of an insulating material arranged to surround or enclose a portion of the lead frame structure. The body can be formed on the lead frame structure before individualization, so that the individual lead frame portions are electrically isolated from each other and mechanically supported by the body within an individual LED package. The body forms a cup or recess, at the bottom of the recess, where one or more LED chips can be mounted on the lead frame. A portion of the lead frame structure may extend from the recess through the body, protruding to the outside of the body or becoming accessible to the outside of the body to provide external electrical connections. A sealing material such as silicone or epoxy can be filled into the recess to seal one or more LED chips.

[0049] 【0089】As used herein, photomodifying materials may include many different materials, including light-reflecting materials that reflect or direct light, light-absorbing materials that absorb light, and materials that act as thixotropic agents. As used herein, the term “light-reflecting” refers to a material or particle that reflects, refracts, or directs light. In the case of light-reflecting materials, the photomodifying material may include at least one of fused silica, fumed silica, titanium dioxide (TiO2), or metal particles suspended in a binder such as silicone or epoxy. In the case of light-absorbing materials, the photomodifying material may include at least one of carbon, silicon, or metal particles suspended in a binder such as silicone or epoxy. Light-reflecting and light-absorbing materials may comprise nanoparticles. In certain embodiments, the photomodifying material may be generally white in order to reflect and direct light. In other embodiments, the photomodifying material may be generally opaque, i.e., black, in order to absorb light and enhance contrast.

[0050] 【0090】 In certain embodiments, the photomodifying material includes both a light-reflecting material and a light-absorbing material suspended in a binder. The weight ratio of the light-reflecting material to the binder may range from about 1:1 to about 2:1. The weight ratio of the light-absorbing material to the binder may range from about 1:400 to about 1:10. In certain embodiments, the total weight of the photomodifying material includes any combination of the binder, the light-reflecting material, and the light-absorbing material. In some embodiments, the binder may constitute a weight percentage ranging from about 10% to about 90% of the total weight of the photomodifying material. The light-reflecting material may constitute a weight percentage ranging from about 10% to about 90% of the total weight of the photomodifying material. The light-absorbing material may constitute a weight percentage ranging from about 0% to about 15% of the total weight of the photomodifying material.

[0051] 【0091】In further embodiments, the light-absorbing material may comprise a weight percentage ranging from about 0% to about 15% of the total weight of the photomodified material. In further embodiments, the binder may comprise a weight percentage ranging from about 25% to about 70% of the total weight of the photomodified material. The light-reflecting material may comprise a weight percentage ranging from about 25% to about 70% of the total weight of the photomodified material. The light-absorbing material may comprise a weight percentage ranging from about 0% to about 5% of the total weight of the photomodified material. In further embodiments, the light-absorbing material may comprise a weight percentage ranging from about 0% to about 5% of the total weight of the photomodified material.

[0052] 【0092】 Figure 1 is a top view of an LED package 100, which includes a lead frame structure collectively formed by a plurality of leads 102-1 to 102-6, a body or housing 104 that houses a portion of the lead frame structure, and a sealing layer 106 disposed within a recess 103 formed by the housing 104. The sealing layer 106 can surround and at least partially cover one or more LED chips 108-1 to 108-3.

[0053] 【0093】 Figure 2 is a cross-sectional view of the LED package 100 of Figure 1. The LED package 100 includes LED chips 108-1 to 108-3, which are mounted and electrically coupled to leads 102-1 to 102-3 respectively and electrically coupled to the corresponding leads 102-4 to 102-6 via wire bonds 109. In Figure 1, a single wire bond 109 is shown for each LED chip 108-1 to 108-3, but it is understood that the various LED chips 108-1 to 108-3 may embody a lateral structure to which a second wire bond may be applied to provide electrical coupling.

[0054] 【0094】In certain embodiments, each of the LED chips 108-1 to 108-3 may be configured to emit a different wavelength than the other LED chips. For example, LED chip 108-1 may be configured to emit red light, LED chip 108-2 may be configured to emit green light, and LED chip 108-3 may be configured to emit blue light. In certain embodiments, the differences between the red, green, and blue light emission may necessitate that LED chip 108-1 be formed from a different material system than the other LED chips 108-2, 108-3. In even further embodiments, the differences between LED chips 108-1 to 108-3 may include different chip shapes, such as LED chip 108-1 being thicker than LED chips 108-2, 108-3. Although three LED chips 108-1 to 108-3 are shown, the principles disclosed herein are applicable to any number of LED chips in the LED package 100. The recess 103 is located at the bottom of the recess 104 F and one or more recessed side walls 104 S This may include: Leads 102-1 to 102-6 may be arranged to penetrate the housing 104, and a portion of leads 102-1 to 102-6 may be located at the bottom of the recess 104. F It is positioned along or at the bottom of the recess 104 F It will be exposed.

[0055] 【0095】 In Figure 1, LED chips 108-1 to 108-3 are arranged in a single row, but in other embodiments, LED chips 108-1 to 108-3 are arranged, for example, with each chip located at the bottom of a recess 104 FIt should be recognized that they can be arranged in different configurations, such as being uniformly arranged around the center position. In other embodiments, the arrangement can be based on the color emitted by the LED chip. For example, an LED chip that emits red light can be arranged at the center of the LED package. Since the shape of the LED package 100 may increase the possibility of high light output efficiency of the central chip, and also since equivalent red LED chips may be more expensive than green or blue LED chips of equivalent absolute intensity, smaller red LED chips can be used, thereby saving costs. 【0056】 【0096】 As best shown in FIG. 2, the encapsulation layer 106 is disposed along the bottom 104 of the recess and covers a portion of the leads 102-1 to 102-6 disposed along the bottom 104 of the recess. Depending on the various shapes of the LED chips 108-1 to 108-3, the encapsulation layer 106 may cover one or more sidewalls of the LED chips 108-1 to 108-3 and a portion of the upper surface of the LED chips 108-1 to 108-3. For example, one or more portions of the LED chip 108-1 can extend above the upper surface of the encapsulation layer 106. The encapsulation layer 106 may include epoxy or silicone depending on the application. In a further embodiment, the encapsulation layer 106 may be configured to be light transmissive and / or light transparent with respect to the wavelength of the light generated by the LED chips 108-1 to 108-3. In an example where the LED chip 108-1 extends above the first encapsulation layer 106-1, one or more portions of the LED chip 108-1, such as the upper surface of the LED chip 108-1, can extend into or be present within the light collector 114. 【0057】 【0097】 ​​​​​​Although Figure 2 does not show wire bond 109, this is solely for the purpose of facilitating the illustration, and it should be recognized in Figure 2 and the remaining diagrams in the detailed description that LED chips 108-1 to 108-3 may include wire bonds for electrically coupling LED chips 108-1 to 108-3 to the corresponding leads 102-4 to 102-6.

[0058] 【0098】 The light concentrator 114 can be positioned above the LED chips 108-1 to 108-3 and the sealing layer 106. The light concentrator can be formed from epoxy, silicone, or some other light-transmitting material. The upper surface of the light concentrator 114 can be coated with a reflective coating 112, except for an uncoated opening 110 at the apex, center, or near the top of the light concentrator 114. Light emitted from the LED chips 108-1 to 108-3 enters the light concentrator 114, is reflected once or more by the reflective coating 112, mixed within the light concentrator, and then finally exits the light concentrator 114 through the opening 110. Light mixing within the concentrator 114 before emission through aperture 110 improves the light emission pattern and reduces color due to angular shift of the LED package 10, as the light from each of the LED chips 108-1, 108-2, and 108-3 appears to be emitted from a single light-emitting point or area (aperture 110) rather than from three separate locations. Where this disclosure refers to a single light-emitting point, it should be recognized that this refers to a single light source (e.g., an LED chip, or the output of multiple LED chips from aperture 110) and not from a mathematical standpoint. In this standpoint, point can be a term that represents a light source smaller than the described LED package or system, and the size may vary by the entire system.

[0059] 【0099】In embodiments, the reflective coating 112 on the light condenser 114 may be a metal or metal oxide deposited or layered on the light condenser 114. For example, in one embodiment, the reflective coating 112 may be a metal cladding (e.g., silver, aluminum, etc.), and in another embodiment, it may be a TiO2 surface deposit, paint, or coating. In yet another embodiment, the reflective coating 112 may comprise a diffuse reflector from either texturing or fine particles in a medium (e.g., pigment). In addition, the reflective coating 112 may be a filled layer of epoxy or silicone comprising a reflector such as TiO2. The material of the reflective coating can be selected based on the desired luminescence characteristics of the LED package, with a higher reflectivity material being used if higher intensity luminescence is desired. In the embodiment shown in Figure 2, the reflective coating 112 is shown as a thin coating on the surface of the light condenser 114, but in other embodiments, the reflective coating 112 may be a thicker layer as described above.

[0060] 【0100】 Referring to Figure 3, cross-sectional views of LED packages 100 having different shaped concentrators 114 according to embodiments of the present disclosure are shown. The concentrator 114 in Figure 3 has a stem portion 116 which may have a diameter approximately equal to the diameter of the opening 110. The stem portion 116 may be cylindrical in shape, protruding from the top, center, or apex of the concentrator 114. In other embodiments, the stem portion 116 may have a shape other than cylindrical. The stem portion 116 may be positioned at a height such that there is no direct line of sight (exemplified by line 118) from the LED chips 108-3 and 108-1 to the opening 110, so that at least a portion of the light emitted by the LED chips 108-3 and 108-1 is deflected by any of the other surfaces, such as the reflective coating 112, the recessed bottom 104 FThe light is reflected at least once from other LED chips or sidewalls before exiting the condenser 114 through the aperture 110. Therefore, the height of the stem portion 116 can vary depending on the diameter of the aperture 110 and / or the distribution or arrangement of the LED chips 108-1, 108-02, 108-3 within the housing 104. For example, a lower stem portion height results in a narrower aperture 110, satisfying the condition that light is reflected at least once before exit. Alternatively, an increased stem portion height may widen the aperture 110 depending on the desired emission characteristics. In this example, the width of the aperture 110 can be less than 10% of the width of the housing 104 or the width of the lens positioned above the condenser 114 (see Figures 4-8 and 12). In this embodiment, the aperture can be larger than 50 μm. In this embodiment, the height of the stem portion ranges from the absence of the stem portion as shown in Figure 2 to three times the height of the concentrator base portion (for example, the height of the concentrator 114 without the stem portion), or from the base of the stem to the bottom of the recess 104 F The range can be up to three times the distance to the condenser 114. In another embodiment, the stem portion can be greater than three times the height of the condenser 114. In the embodiment, the width of the columnar projection and the opening is in the range of 25% to 250% of the lateral dimension of one of the LED chips among the one or more LED chips.

[0061] 【0101】 In some embodiments, the light concentrator 114 can have a variety of different shapes or configurations, such as being relatively flat or thin. The angle of the top surface can also be reversed to make the overall shape concave rather than convex. In other embodiments, the light concentrator 114 can be omitted entirely, and a single opening 110 can be formed above the capsule 106.

[0062] 【0102】 In this embodiment, the upper part of the stem portion 116 is the side wall 104 of the housing 104, as shown in Figure 3. S It may extend above the stem portion 116. In other embodiments, the upper part of the stem portion 116 is the side wall 104 S It may be at the same height as the top, or in other embodiments, the side wall 104 SIt can be lower than the top.

[0063] 【0103】 Figure 4 is a cross-sectional view of an LED package having a light condenser and a lens according to an embodiment of the present disclosure. 【0104】 Figure 4 is similar to the embodiment shown in Figure 2, except that a filler material 122 is added around and above the concentrator 114. The opening 110 is not covered by the filler material 122. In various embodiments, the filler material 122 may include a photomodifying material, such as a light-reflecting or light-absorbing material, that completely or partially reflects, blocks, or reduces light passing through or around the reflective coating 112 of the concentrator, ensuring that the majority of the light emitted by the LED package 100 passes through the opening 110. The filler material may be epoxy or silicone having a composition configured to be light-reflecting or light-blocking. In embodiments, the filler material 122 may be left uncovered around the opening 110, at least a portion of the concentrator 114.

[0064] 【0105】 A masking layer 124 can be deposited on top of the filler material 122. The masking layer 124 improves contrast and further enhances the FFP of the LED package 100. Details of the masking layer are shown in Figure 10. The masking layer 124 can be black or light-absorbing.

[0065] 【0106】 Compared to the embodiment shown in Figure 2, Figure 4 also includes a lens 120 positioned above the concentrator 114, the filler material 122, and the masking layer 124. In some embodiments, as shown in Figure 4, the lens 120 may also be positioned above at least a portion of the housing 104.

[0066] 【0107】The lens 120 can be a lens formed on top of the rest of the LED package 100 using a molding process, or a lens formed as a separate element and later fixed to the LED package 100 using an adhesive. The lens 120 can be glass, silicone, or another suitable light-transmitting material.

[0067] 【0108】 Furthermore, although Figure 4 shows the top of the filler material 122 forming a straight line between the housing 104 and the opening 110, it should be recognized that due to the expansion or contraction of the surface adhesive and sealing material during the curing process, the filler material 122 may sag in the center or rise at or near the edges of the housing 104 or the concentrator 114. Other shapes may be considered and determined by design and natural process characteristics.

[0068] 【0109】 In the embodiment shown in Figure 5, the configuration is similar to that of Figure 3, except for the filler material 122, the masking layer 124, and the lens 120, except that in some embodiments, the filler material 122 may not cover part of the stem portion 116. In other embodiments, the filler material 122 may cover the entire stem portion 116. In embodiments where the filler material 122 covers part of the stem portion 116, although not shown, the filler material 122 must transmit light at least partially, and if the transmittance is low, the portion covering the stem portion 116 must be thin enough to provide the expected light output efficiency. It should also be noted that in Figure 5, the stem portion 116 is higher than the wall of the housing 104, but in other embodiments, the top of the stem portion 116 may be the same height as the wall of the housing 104 or lower.

[0069] 【0110】Figure 6 shows another example of the LED package 100, similar to those shown in Figures 4 and 5, except that the shape of the light concentrator 114 is different. The light concentrator 114 in Figure 6 can form a dome shape with a curved upper end, whereas the light concentrators in Figures 2 to 5 have a conical shape with a straight upper end. The curved end of the dome-shaped light concentrator 114 in Figure 6 can provide better light extraction characteristics than the conical light concentrators in Figures 2 to 5.

[0070] 【0111】 Figures 7 and 8 are cross-sectional views of an LED package 100 similar to those shown in Figures 5 and 6, except that the light concentrator 114 in Figures 7 and 8 is formed within the light concentrator using a diffusing material that can further promote the mixing of light within the light concentrator 114. The diffusing material can be silica or TiO2 or any other light scattering material according to embodiments of the present disclosure.

[0071] 【0112】 Figure 9 shows a condenser 114 according to an embodiment of the present disclosure. The condenser 114 shown in Figure 9 is a condenser 114 without a metal or metal oxide reflective coating 112. The illustrated version of the condenser 114 is a condenser 114 having a stem portion 116. The condenser 114 is formed by molding a plurality of condensers with epoxy or silicone, and then the plurality of condensers can be coated with a metal or metal oxide coating for the reflective coating 112. As already discussed, a masking layer 124 may be added above 112 to provide a non-reflective or black layer to improve contrast. In exemplary embodiments, if a sufficiently thick aluminum layer is used for the reflective coating 112, then the masking layer 124 can be provided by anodizing with a black pigment. Next, the top of the condenser can be polished or ground to remove the reflective coating 112 from the top of the stem portion 116, creating an opening 110. Next, the light concentrators can be separated from each other and positioned above the LED chip 108 and the sealing material 106 in the recess 103.

[0072] 【0113】Figure 10 is another cross-sectional view of an LED package having a concentrator and filler material according to an embodiment of the present disclosure. Figure 10 is a schematic cross-sectional view of an actual LED package 100. As can be seen from Figure 10, the filler material 122 may have a meniscus shape due to surface adhesion to the stem portion 116 and the walls of the housing 104, shrinkage of the encapsulating material, or a designed process. The black masking layer 124 appears to cover the top of the filler material 122, but the opening 110 of the concentrator 114 remains uncovered. The embodiment shown herein also shows a encapsulating layer 106 surrounding and at least partially covering the LED chips 108-1, 108-2, 108-3.

[0073] 【0114】 Figure 11 is a perspective view of an LED package 100 having a light concentrator 114 and a filler material 122 according to an embodiment of the present disclosure. The LED package 100 shown in Figure 11 is before the masking layer 124 is applied and before the lens 120 is molded or fixed. The opening 110 is visible in the center of the LED package 100 surrounded by the filler material 122.

[0074] 【0115】 Figure 12 is a perspective view of an LED package 100 having a lens 120 according to an embodiment of the present invention. The lens 120 is positioned above the top of the filler material 122 and the masking layer 124, and in some embodiments similarly extends over at least a portion of the housing. The lens 120 can further improve the FFP of the light emitted by the LED package.

[0075] 【0116】 Figure 13 shows a representation of an LED package having an axis in which light intensity is plotted as a function of viewing angle in the FFP graphs of Figures 14A-14B and Figures 15A-15B. For example, an FFP graph of light intensity against viewing angle can be plotted along the YY axis 131 or along the XX axis 133, with the light intensity corresponding to chips 108-1, 108-2, and 108-3.

[0076] 【0117】Figures 14A and 14B show graphs of FFP for a conventional LED package. The conventional LED package is similar to the LED package in Figure 11, but lacks the condenser 114 or lens 120 used in this disclosure. Figure 14A shows the FFP along the YY axis 131, which shows the light intensity 132 at different + / - theta values ​​134 plotted in degrees, where theta=0 is directly above or opposite the LED package. In the embodiments shown in Figures 14A and 14B, the plotted line 137 corresponds to light from LED chip 108-1, line 135 corresponds to light from LED chip 108-2, and line 136 corresponds to light from LED chip 108-3. In Figure 14A, the peak intensity of LED chip 108-2 is theta 0, while the maximum delta theta of LED chips 108-1 and 108-3 relative to the central peak of chip 108-2 is 10–15 degrees, which corresponds to the peak intensity of these chips at a viewing angle of 10–15 degrees relative to directly above or opposite the LED package. Plot lines 135, 136, and 137 are nearly identical along the XX axis 133 shown in Figure 14B, because the chips are positioned along a line perpendicular to the XX axis 133 within the housing 104 of the LED package. In this regard, color uniformity along the XX direction is generally considered good and meets the requirements of most display systems.

[0077] 【0118】Figures 15A and 15B show graphs of the far-field patterns of the LED package 100 from Figure 12 according to embodiments of the present disclosure. Figure 15A shows the FFP of light intensity 132 at different + / - theta values ​​134 along the YY axis 131, where theta=0 is directly above or opposite the LED package 100. In Figures 15A and 15B, the plotted line 137 corresponds to light from LED chip 108-1, line 135 corresponds to light from LED chip 108-2, and line 136 corresponds to light from LED chip 108-3. In Figure 15A, the peak intensities of LED chips 108-1, 108-2, and 108-3 are all close to theta=0, the normalized intensity difference along the YY axis 131 is close to zero, corresponding to excellent color uniformity across all YY viewing angles and a delta-theta value close to zero. The color uniformity along the XX axis 133, as shown in Figure 15B, is also excellent, being almost zero, and the delta theta value is also almost zero. Figures 15A and 15B clearly demonstrate the improvement in delta theta between the LED package disclosed herein with a light condenser and a conventional LED package without a light condenser, particularly when comparing the color uniformity along the YY direction in Figures 14A and 15A.

[0078] 【0119】Figures 16A and 16B show another representation of the FFP of the LED package disclosed herein compared to a conventional LED package without a lens or focuser, according to embodiments of the present disclosure. In Figure 16A, the axes are represented by the total envelope full width at half maximum (TEFWHM) on the x-axis 139 and the intensity value % difference (IV%DIFF) on the y-axis 138, with lines 140, 141, and 142 representing the red, blue, and green colors emitted by a conventional LED package without a focuser or lens along the YY axis 131. Lines 143, 144, and 145 represent the red, blue, and green colors emitted by an LED package with a focuser and lens along the YY axis. Lines 140-142 are defined as the % difference in intensity values ​​of trace 135 with theta=0 relative to chip 108-2, as shown in Figure 14A. Lines 143 to 145 are defined as the percentage difference in intensity values ​​of trace 135 with respect to tip 108-2, where theta=0, as shown in Figure 15A. Thus, lines 142 and 145, corresponding to the green light emitted by tip 108-2, are flat lines with IV%DIFF=0 across the entire range of TEFWHM.

[0079] 【0120】 TEFWHM corrects the viewing angle of the component and provides an envelope in which the intensity of each color exceeds 50% at a given theta. IV%DIFF is the difference with respect to the central FFP line (the central green LED chip in the sample embodiment) at theta=0. The reference curve for IV%DIFF is based on the chip that is the most centrally located anchor FFP, which in the embodiments disclosed herein is LED chip 108-2, in this case green. Thus, for example, the IV%Diff of red (R) relative to green (G) is given by the following formula:

[0080] 【0121】

[0081] 【number】

[0082] 【0122】Plots of IV%Diff for red and blue respectively more clearly show theta offset and RGB full peak overlap, allowing for a more direct comparison of components with different viewing angles.

[0083] 【0123】 Figure 16B is a similar graph that has the same line, except that it is viewed along the XX axis 133. 【0124】 Figures 17A and 17B show graphs of FFP for an LED package with a lens but without a focuser. Figure 17A shows the FFP of light intensity 132 at different + / - theta values ​​134 plotted in degrees along the YY axis 131, where theta=0 is directly above or opposite the LED package. In the embodiments shown in Figures 17A and 17B, the plotted line 137 corresponds to light from LED chip 108-1, line 135 corresponds to light from LED chip 108-2, and line 136 corresponds to light from LED chip 108-3.

[0084] 【0125】 Figures 18A and 18B show another representation of the FFP of the lensed LED package disclosed herein, compared to the lensed LED package without a focuser, according to embodiments of the present disclosure. In Figures 18A and 18B, lines 146, 147, and 148 of red, blue, and green light emitted by the lensed but non-focuser-containing LED package are plotted, while lines 149, 150, and 151 are lines of red, blue, and green light emitted by the LED package including both a focuser and a lens. It should be recognized that lines 149, 150, and 151 correspond to lines 143, 144, and 145 in Figures 16A and 16B above. The plots in Figure 18A are along the YY axis 131, and the plots in Figure 18B are along the XX axis 133.

[0085] 【0126】Referring to Figure 19, a portion of an LED display screen 152, which is, for example, an indoor and / or outdoor screen, is schematically shown, and this screen typically comprises a driver printed circuit board (PCB) 154 in which a number of surface-mount devices (SMDs) 156 are arranged in a matrix, with each SMD defining a pixel. The SMDs 156 may comprise devices such as those shown in the embodiments of Figures 1 to 8 and Figures 10 to 12. The SMD devices 156 are electrically connected to traces or pads on the PCB 154 that are connected to respond to appropriate electrical signal processing and driver circuit configurations (not shown). As disclosed above, Figure 19 shows LED chips 108 arranged in a row, but it should be recognized that in other embodiments, the LED chips 108 may be arranged in different configurations.

[0086] 【0127】 According to aspects of this disclosure, evaluation parameters have been developed for comparing the uniformity and color mixing in the far-field patterns of the LED packages disclosed herein. As disclosed herein, the figure of merit (FOM) has been developed to define a color quality index metric that characterizes the color quality and uniformity of far-field emission in multi-color and multi-chip LED packages. For example, the FOM of a color quality index as described herein may be useful in characterizing the red, green, and blue wavelength peaks from an LED package containing red LED chips, blue LED chips, and green LED chips. To visualize the FOM in various graphs, first, the reference total envelope full width at half maximum (TEFWHM) for multi-chip LED emission is used. REF ) is determined. TEFWHM REF Although not a component of FOM, it is generated as a technique for normalizing the x-axis (e.g., theta angle) to visualize and compare different emission delta patterns. TEFWHM REF It corrects the viewing angle and provides an envelope in which the intensity of each color exceeds 50% for a given theta. TEFWHM REFThe FOM may be used to generate various graphs of FOM to compare various arrangements of LED packages in accordance with the principles of this disclosure. As described herein, the FOM is derived by evaluating the emission peaks from multiple LED chips in a far-field pattern with respect to the central peak of the far-field pattern (viewing angle from the center is 0°), for which the area under the curve is determined and integrated for all absolute values ​​of the noise-corrected deviation from the center, the ratio of the sum of the areas under the curve to all possible values ​​is derived and normalized so that the range from minimum to maximum is 0 to 1. REF This is used to visualize the graphs in Figures 21A to 21F, but the actual calculation of FOM is done using TEFWHM. REF It is unrelated to the number of [something].

[0087] 【0128】 Figure 20A is a graph of an exemplary far-field pattern in the VV direction of an exemplary LED package, and further, the TEFWHM for total light emission from LED chips 108-1 to 108-3. REF This shows that the exemplary LED package is similar to the LED package in Figure 12, but without the concentrator 114 and filler material 122 of this disclosure. Figure 20B is a graph of the exemplary far-field pattern in the HH direction of the LED package shown in Figure 20A, and further, the TEFWHM for total light emission from LED chips 108-1 to 108-3. REF This shows the selection of data for LED packages without the light concentrator 114 and filler material 122, and the TEFWHM of any LED package. REF This is for illustrative purposes to illustrate the following. Raw far-field pattern inputs of normalized luminous intensity (Iv) versus theta (θ) are collected to generate plot lines for each LED chip 10⁸-1 to 10⁸-3. From the data, the left (L) plot line is defined as the most negative θ value (i.e., 10⁸-3), the center (C) plot line is defined as the center peak wavelength θ=0 (i.e., 10⁸-2), and the right (R) plot line is defined as the most positive θ value (i.e., 10⁸-1). Primary peak TEFWHM REFThe input is the maximum negative theta (θ) in the vertical (VV) and horizontal (HH) directions where the normalized luminosity is 50% (Iv(θ)=0.5). min ) and maximum positive theta (θ max ) may be defined as ). In Figures 20A and 20B, a horizontal dashed line is drawn where Iv(θ)=0.5, and the vertical line is TEFWHM REF The corresponding boundaries are shown.

[0088] 【0129】 Noise reduction of the raw far-field pattern (NoiseLVL) can be applied to a noise level appropriate to the features in the data, capturing all ancillary peaks and emission while baseline-setting other values ​​for model simplification. For example, for Figures 20A and 20B, the noise level is set to Iv(θ)=0.05, and Iv(θ)<0.05 corresponds to Iv(θ)=0. In practice, the noise level may be set to other levels based on the relative noise in various far-field patterns. TEFWHM for normalizing theta(θ) in the HH and VV directions REF The value is calculated using the following formula to find the maximum negative theta (θ) min ) and maximum positive theta (θ max It may also be defined by adding the absolute values ​​of ).

[0089] HorzTEFWHM Ref =|Horzθ max |+|Horzθ min | VertTEFWHM Ref =|Vertθ max |+|Vertθ min | As mentioned above, the horizontal dashed line in Figures 20A and 20B is drawn at Iv(θ) = 0.5, and the vertical line is TEFWHM REF This indicates the corresponding boundary that defines it.

[0090] 【0130】 Subsequently, the x-axis value of theta (θ) is TEFWHM REF It may be corrected by the HH value of theta (θ), HorzTEFWHMRef The VV value of theta (θ) is normalized using VertTEFWHM Ref Using this method, the values ​​are normalized, and a new x-axis value defined as the normalized TEFWHM is obtained, as shown in Figures 21E to 21H.

[0091] 【number】

[0092] 【0131】 The noise-corrected intensity value (IvNC(θ)) may also be derived by the following conditional equation.

[0093] 【number】

[0094] 【0132】 The percentage of noise-corrected intensity values ​​where all values ​​are non-zero (IvNC%(θ)) may be derived by the following conditional expression.

[0095] 【number】

[0096] The absolute value of IvNC%(θ) may then be defined as |IvNC%(θ)| for all plot lines, both in the VV and HH directions, for a total of six plot lines: left, center, and right.

[0097] 【0133】Next, for each plotted line, the net intensity coefficient (IvNCSumAll) may be defined by integrating the area under the curve over all |IvNC%(θ)| contributions for the total quantifiable metric of the optical quality deviation or delta from the central far-field pattern over all θ values. The equation ∫|IvNC%(θ)|dθ may be performed for the left and right plotted lines in both the VV and HH directions. Functionally, it is realized by the following equation for the sum of all |IvNC%(θ)| for all θ values ​​of the left and right plotted lines in both the VV and HH directions.

[0098] 【number】

[0099] The values ​​of the central plot line are all zero by definition and do not contribute to this part, so they are omitted. Subsequently, the net intensity coefficient ratio is defined by the following ratio, where IvNCSumALL Max This refers to the maximum possible value for IvNCSumAll.

[0100] 【number】

[0101] 【0134】 Subsequently, the net intensity coefficient ratio (IvNCSum Ratio FOM may be generated by normalizing ). For example, in the case of data acquisition having 91 data points for each far-field pattern scan of the left and right plot lines in both the VV and HH directions, IvNCSumALL Max =36400. The 91 data points represent 91 left VV, right VV, left HH, and right HH, with the center point 0 omitted. FOM may also be evaluated as the net intensity coefficient ratio normalized to the minimum ratio to extend the range (0 to 1), and is defined by the following formula:

[0102] 【number】

[0103] Based on the overall structure of the example LED package, for the reference low range, max(IvNCSum Ratio ) is defined as 1, and min(IvNCSum Ratio ) is set to 0.6.

[0104] 【0135】 As described above, in the case of an LED package having multiple LED chips that generate multiple peak wavelengths, the FOM of the far-field pattern of the LED chips defines a color quality index relating to the uniformity of the far-field pattern with respect to the central peak wavelength. The FOM of the far-field pattern may be defined as a function of a ratio normalized based on a minimum criterion of 0.6, which is the ratio of the area under the curve for all absolute values ​​of the percentage differences with respect to the central peak wavelength, (4) the area under the curve for all possible values ​​normalized from a minimum to a maximum value between 0 and 1.

[0105] 【0136】 As described herein, FOM may then be used to compare and / or classify LED packages by their respective design, symmetry, and target FWHM value. Various classification designs may include single-cavity or multi-cavity LED packages, with or without curved lenses. Comparison may be achieved by ranking FOM within the classification. For example, the FOM of various LED packages with single-cavity and symmetrical designs may be ranked for a particular target FWHM. In another example, the FOM of various LED packages with multi-cavity and asymmetrical designs may be ranked for a different target FWHM.

[0106] 【0137】Figures 21A to 21H are plots representing the generation of FOM for another LED package similar to the LED package in Figure 12, but without the concentrator 114 and filler material 122 of this disclosure, and described by the above formula. The selection of LED packages is for illustrative purposes only to show the generation of FOM for any LED package. Figure 21A is a graph of the VV direction far-field pattern of the LED package in raw data format. Figure 21B is a graph of the HH direction far-field pattern of the LED package shown in Figure 21A in raw data format. Figure 21C is a graph of the VV direction noise-corrected far-field pattern (NC FFP) added to the data from Figure 21A. Figure 21D is a graph of the HH direction noise-corrected far-field pattern (NC FFP) added to the data from Figure 21C. In this regard, Figures 21C and 21D represent the above-mentioned noise-corrected intensity values ​​(IvNC(θ)).

[0107] 【0138】 Next, the noise-corrected intensity value percentage IvNC%(θ) relative to the center is determined and plotted. Figure 21E is a graph showing the delta from the center, i.e., IvNC%(θ), using the TEFWHM value normalized in the VV direction for the plotted line in Figure 21C. Figure 21F is a graph showing the delta from the center, i.e., IvNC%(θ), using the TEFWHM value normalized in the HH direction for the plotted line in Figure 21D. In both Figure 21E and Figure 21F, the plotted line for LED chip 108-2 is zero because the other plotted lines 108-1 and 108-3 represent the deviation of the optical quality of the centrally located LED chip 108-2 from the FFP.

[0108] 【0139】Figure 21G is a graph showing the absolute value |IvNC%(θ)| of the plotted line in Figure 21E, and Figure 21H is a graph showing the absolute value |IvNC%(θ)| of the plotted line in Figure 21F. Next, the net intensity coefficient (IvNCSumAll) for a quantifiable index of the optical quality deviation or delta from the central far-field pattern may be determined based on the absolute value |IvNC%(θ)| as described above. Finally, the FOM is the net intensity coefficient IvNCSumAll and the possible maximum value IvNCSumALL Max It may also be derived by defining a ratio and normalizing it as described by the FOM formula above.

[0109] 【0140】 Figure 22 is a summary table 158 showing the FOM, or normalization ratio, for various LED package configurations. As described above, the FOM as described herein is essentially an RGB color quality index metric that characterizes the color quality and far-field emission uniformity of multi-color and multi-chip LED packages. In Figure 22, Examples 1 to 7 represent conventional multi-cavity LED packages in which red, blue, and green LED chips are arranged in separate cavities. Examples 1 to 6 represent symmetrical LED packages with an FWHM target of 30°, while Example 7 represents an asymmetrical LED package with directional emission FWHM targets of 45° and 90°. Example 8 represents a conventional single-cavity LED package with red, blue, and green LED chips, without a curved lens (i.e., with a flat top sealing material in the recess), and with an FWHM target of 115°. Examples 1 through 8 are provided as a reference for comparison of single-cavity and lensed LED packages having the focusers of this disclosure targeting narrower FWHM values ​​such as 30°. Region 160 is shown with FOM values ​​from 0.8 to 0.96 to represent industry-acceptable target FOM values.

[0110] 【0141】As further shown in Figure 22, FOM values ​​for the LED package described above for Figure 12 are also provided. Specifically, FOM values ​​are provided for the configuration of the LED package of Figure 12 having the internal structure of the concentrator 114, filler material 122, and black masking layer 124 shown in Figure 10. The FOM of the LED package of Figure 12 is 0.995, which is higher than the entire range of the industry-acceptable region 160. Thus, aspects of the present disclosure provide multi-chip in a single-cavity LED package arrangement where the FWHM target is narrow (e.g., less than 60°, less than 50°, or 30° or less) and the FOM value is in the range of 0.7 to 0.995, or 0.8 to 0.995, or 0.9 to 0.995, or any range above the industry-acceptable highest standard value of 0.96.

[0111] 【0142】 Any of the embodiments described herein, and / or any of the various individual embodiments and features described herein, may be combined for further advantages. Any of the various embodiments disclosed herein may be combined with one or more other disclosed embodiments unless otherwise indicated herein.

[0112] 【0143】 Those skilled in the art will recognize improvements and modifications to preferred embodiments of this disclosure. All such improvements and modifications are considered to fall within the scope of the concepts disclosed herein and the claims that follow.

Claims

[Claim 1] Light-emitting diode (LED) package, One or more LED chips, At least one light condenser positioned above one or more LED chips, the light condenser being formed from a first light-transmitting material, An LED package comprising at least one reflective coating on the surface of the light concentrator, the reflective coating comprising at least one reflective coating that forms at least one opening. [Claim 2] The LED package according to claim 1, wherein the opening of the light concentrator is located at the top of the stem portion of the light concentrator. [Claim 3] The LED package according to claim 2, wherein the first width of the stem portion and the opening is less than 10% of the second width of the housing. [Claim 4] The LED package according to claim 2, wherein the width of the opening is at least 50 μm. [Claim 5] The LED package according to claim 2, wherein the height of the stem portion is such that at least a portion of the light emitted by at least one of the one or more LED chips is reflected at least once by at least one surface before exiting the opening. [Claim 6] The LED package according to claim 2, wherein there is no direct line of sight between the opening and a large portion of at least one of the one or more LED chips. [Claim 7] The LED package according to claim 1, wherein a lens having a curved surface is at least partially fixed above the light concentrator. [Claim 8] The LED package according to claim 1, further comprising a packed layer surrounding the light concentrator that blocks stray light from the light concentrator. [Claim 9] The LED package according to claim 8, further comprising a masking layer on the filling layer. [Claim 10] The LED package according to claim 1, wherein the light concentrator comprises a diffusion material that diffuses the light emitted by the one or more LED chips. [Claim 11] The LED package according to claim 2, wherein the upper surface of the light concentrator is at least one of curved or straight, and the stem portion is at the apex of the light concentrator. [Claim 12] The LED package according to claim 1, wherein the reflective coating comprises at least one of a metal or a metal oxide. [Claim 13] The LED package according to claim 1, wherein the far-field pattern of the light emitted by each of the multiple LED chips has a maximum delta theta of less than 2 degrees. [Claim 14] The LED package according to claim 1, wherein the first light-transmitting material is epoxy or silicone. [Claim 15] A housing that forms a recess having a recessed bottom and one or more recessed side walls, wherein the one or more LED chips are disposed within the recess, The LED package according to claim 1, further comprising a lead frame structure that extends through the housing, a portion of which is arranged along the bottom of the recess. [Claim 16] Light-emitting diode (LED) package, One or more LED chips, An LED package comprising at least one light-gathering device at least partially positioned above one or more LED chips, wherein the light-gathering device has a columnar projection, and the light-gathering device is formed from a first light-transmitting material. [Claim 17] The LED package according to claim 16, wherein the first width of the columnar projection is in the range of 25% to 250% of the lateral dimension of one of the one or more LED chips. [Claim 18] The LED package according to claim 16, wherein there is no direct line of sight between at least 50% of the upper surface of one of the one or more LED chips and the opening of the light concentrator. [Claim 19] The LED package according to claim 16, wherein the light concentrator comprises a diffusion material that diffuses the light emitted by the one or more LED chips. [Claim 20] The LED package according to claim 16, wherein the far-field pattern of the light emitted by each of the multiple LED chips has a maximum delta theta of less than 2 degrees. [Claim 21] A housing that forms a recess having a recessed bottom and one or more recessed side walls, The LED package according to claim 16, further comprising a lead frame structure that extends through the housing, a portion of which is arranged along the bottom of the recess. [Claim 22] The LED package according to claim 16, further comprising a reflective coating that covers the entire outer surface of the light concentrator except for the reduced opening at the top of the columnar projection. [Claim 23] The LED package according to claim 22, further comprising a lens that at least partially covers the light concentrator. [Claim 24] Light-emitting diode (LED) package, A housing that forms a recess having a recessed bottom and one or more recessed side walls, A lead frame structure that extends through the housing, with a portion of it arranged along the bottom of the recess, One or more LED chips are disposed within the recess and electrically coupled to the lead frame structure, A light concentrator, at least partially located within the recess and above one or more LED chips, is formed from a first light-transmitting material, and comprises: A reflective coating on the surface of the light concentrator, the reflective coating having an opening at the apex of the light concentrator, An LED package comprising a lens having a curved surface fixed above at least a portion of the light concentrator. [Claim 25] Light-emitting diode (LED) display, Display panel and It comprises at least one LED package, and the at least one LED package is One or more LED chips, At least one light condenser positioned above one or more LED chips, the at least one light condenser being formed from a first light-transmitting material, An LED display comprising at least one reflective coating on the surface of the light concentrator, the reflective coating comprising at least one reflective coating that forms at least one opening. [Claim 26] The LED display according to claim 25, wherein a lens having a curved surface is fixed above at least a portion of the light concentrator. [Claim 27] The LED display according to claim 25, wherein the far-field pattern of the light emitted by each of the multiple LED chips has a maximum delta theta of less than 2 degrees. [Claim 28] The LED display according to claim 25, wherein the one or more LED chips are a plurality of LED chips composed of a combination of red, green, and blue LED chips. [Claim 29] Light-emitting diode (LED) package, At least three LED chips configured to generate multiple peak wavelengths, At least one light condenser positioned above the at least three LED chips, the at least one light condenser being formed from a first light-transmitting material, An LED package comprising at least one reflective coating on the surface of the light concentrator, the reflective coating forming an opening. [Claim 30] The LED package according to claim 29, wherein the far-field pattern of the collective light emission from the at least three LED chips has a full width at half maximum of less than 50. [Claim 31] The figure of merit (FOM) of the far-field pattern is in the range of 0.7 to 0.995, and the FOM defines a color quality index relating to the uniformity of the far-field pattern with respect to the central peak wavelength among the plurality of peak wavelengths, and the FOM is, Raw far-field pattern data for each LED chip, The noise-corrected light intensity data of the raw far-field pattern data for each LED chip, Percentage difference from the center of all non-zero noise-corrected light intensity data, The area under the curve for all absolute values ​​of the percentage difference with respect to the central peak wavelength, The LED package according to claim 30, wherein the ratio of the area under the curve for all possible values ​​whose range from minimum to maximum is normalized from 0 to 1 is a function of the ratio normalized based on a minimum criterion of 0.

6. [Claim 32] The LED package according to claim 31, wherein the FOM is in the range of 0.9 to 0.

995. [Claim 33] The LED package according to claim 29, wherein the opening of the light concentrator is located at the top of the stem portion of the light concentrator. [Claim 34] The LED package according to claim 33, wherein the first width of the stem portion and the opening is less than 10% of the second width of the housing. [Claim 35] The LED package according to claim 33, wherein the width of the opening is at least 50 μm. [Claim 36] The LED package according to claim 33, wherein the height of the stem portion is such that at least a portion of the light emitted by at least one of the at least three LED chips is reflected at least once by at least one surface before exiting the opening. [Claim 37] The LED package according to claim 33, wherein there is no direct line of sight between the opening and at least one of the at least three LED chips. [Claim 38] The LED package according to claim 33, wherein there is no direct line of sight between the opening and the at least three LED chips. [Claim 39] The LED package according to claim 33, wherein the upper surface of the light concentrator is at least one of curved or straight, and the stem portion is at the apex of the light concentrator. [Claim 40] The LED package according to claim 29, wherein a lens having a curved surface is at least partially fixed above the light concentrator. [Claim 41] The LED package according to claim 29, further comprising a filler material surrounding at least a portion of the light concentrator and the opening, wherein the filler material is configured to be light-reflective or light-shielding to the light generated by the at least three LED chips. [Claim 42] The LED package according to claim 41, further comprising a masking layer on the filler material, wherein the filler material is located between the light concentrator and the masking layer, and the masking layer is configured to be light-absorbing. [Claim 43] The LED package according to claim 29, wherein the light concentrator comprises a diffusing material that diffuses the light emitted by the at least three LED chips. [Claim 44] The LED package according to claim 29, wherein the reflective coating comprises at least one of a metal or a metal oxide. [Claim 45] The LED package according to claim 29, wherein the far-field pattern of the light emitted by each of the at least three LED chips has a maximum delta theta of less than 2 degrees. [Claim 46] The LED package according to claim 29, wherein the first light-transmitting material is epoxy or silicone. [Claim 47] A housing that forms a recess having a recessed bottom and one or more recessed side walls, wherein at least three LED chips are disposed within the recess, The LED package according to claim 29, further comprising a lead frame structure that extends through the housing, a portion of which is arranged along the bottom of the recess. [Claim 48] Light-emitting diode (LED) package, At least three LED chips configured to generate multiple peak wavelengths, An LED package comprising at least one light-gathering device at least partially positioned above the at least three LED chips, wherein the light-gathering device has columnar projections, and the light-gathering device is formed from a first light-transmitting material. [Claim 49] The LED package according to claim 48, wherein the far-field pattern of the collective light emission from the at least three LED chips has a full width at half maximum of less than 50. [Claim 50] The figure of merit (FOM) of the far-field pattern is in the range of 0.7 to 0.995, and the FOM defines a color quality index relating to the uniformity of the far-field pattern with respect to the central peak wavelength among the plurality of peak wavelengths, and the FOM is, Raw far-field pattern data for each LED chip, The noise-corrected light intensity data of the raw far-field pattern data for each LED chip, Percentage difference from the center of all non-zero noise-corrected light intensity data, The area under the curve for all absolute values ​​of the percentage difference with respect to the central peak wavelength, The LED package according to claim 49, wherein the ratio of the area under the curve for all possible values ​​whose range from minimum to maximum is normalized from 0 to 1 is a function of the ratio normalized based on a minimum criterion of 0.

6. [Claim 51] The LED package according to claim 50, wherein the FOM is in the range of 0.9 to 0.

995. [Claim 52] The LED package according to claim 48, wherein the first width of the columnar projection is in the range of 25% to 250% of the lateral dimension of one of the at least three LED chips. [Claim 53] The LED package according to claim 48, wherein there is no direct line of sight between at least 50% of the upper surface of one of the at least three LED chips and the opening of the light concentrator. [Claim 54] The LED package according to claim 48, wherein the light concentrator comprises a diffusing material that diffuses the light emitted by the at least three LED chips. [Claim 55] The LED package according to claim 48, wherein the far-field pattern of the light emitted by each of the at least three LED chips has a maximum delta theta of less than 2 degrees. [Claim 56] A housing that forms a recess having a recessed bottom and one or more recessed side walls, The LED package according to claim 48, further comprising a lead frame structure that extends through the housing, a portion of which is arranged along the bottom of the recess. [Claim 57] The LED package according to claim 48, further comprising a reflective coating that covers the entire outer surface of the light concentrator except for the reduced opening at the top of the columnar projection. [Claim 58] The LED package according to claim 57, further comprising a lens that at least partially covers the light concentrator. [Claim 59] Light-emitting diode (LED) display, Display panel and It comprises at least one LED package, and the at least one LED package is At least three LED chips configured to generate multiple peak wavelengths, At least one light condenser positioned above the at least three LED chips, the at least one light condenser being formed from a first light-transmitting material, An LED display comprising at least one reflective coating on the surface of the light concentrator, the reflective coating forming an opening. [Claim 60] The LED display according to claim 59, wherein a lens having a curved surface is fixed above at least a portion of the light concentrator. [Claim 61] The LED display according to claim 59, wherein the far-field pattern of the light emitted by each of the at least three LED chips has a maximum delta theta of less than 2 degrees. [Claim 62] The LED display according to claim 59, wherein the at least three LED chips comprise a combination of red, green, and blue LED chips. [Claim 63] The LED display according to claim 59, wherein the far-field pattern of the collective light emission from the at least three LED chips has a full width at half maximum of less than 50. [Claim 64] The figure of merit (FOM) of the far-field pattern is in the range of 0.7 to 0.995, and the FOM defines a color quality index relating to the uniformity of the far-field pattern with respect to the central peak wavelength among the plurality of peak wavelengths, and the FOM is, Raw far-field pattern data for each LED chip, The noise-corrected light intensity data of the raw far-field pattern data for each LED chip, Percentage difference from the center of all non-zero noise-corrected light intensity data, The area under the curve for all absolute values ​​of the percentage difference with respect to the central peak wavelength, The LED display according to claim 63, wherein the ratio of the area under the curve for all possible values ​​whose range from minimum to maximum is normalized from 0 to 1 is a function of the ratio normalized based on a minimum criterion of 0.

6. [Claim 65] The LED display according to claim 64, wherein the FOM is in the range of 0.9 to 0.995.

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