KR20090016694A - Led device with re-emitting semiconductor construction and optical element - Google Patents

Abstract

A light source includes an LED component having an emitting surface, and an optical element having an input surface in optical contact with the emitting surface. The LED component may be or include an LED such as an LED die capable of emitting light at a first wavelength, in combination with a re-emitting semiconductor construction which includes a second potential well not located within a pn junction. The optical element can be an extractor whose shape is converging, diverging, or a combination thereof.

Description

LED DEVICE WITH RE-EMITTING SEMICONDUCTOR CONSTRUCTION AND OPTICAL ELEMENT

Cross Reference with Related Application

This application claims the benefit of US Provisional Patent Application No. 60/804541, filed June 12, 2006 and US Provisional Patent Application No. 60/804824, filed June 14, 2006, The disclosure is incorporated herein by reference in its entirety.

The present invention relates to a light source. More specifically, the present invention relates to a light source comprising an optical element such as a light emitting diode (LED), a re-emitting semiconductor construction, and an extractor as described herein.

Light emitting diodes (LEDs) are solid-state semiconductor devices that emit light when a current passes between an anode and a cathode. Conventional LEDs include one pn junction. The pn junction may comprise an intermediate undoped region, and this type of pn junction may also be called a pin junction. Like non-light-emitting semiconductor diodes, conventional LEDs pass current much more easily in one direction, i.e., the direction in which electrons move from the n-region to the p-region. When current passes through the LED in the "forward" direction, electrons from the n-region recombine with holes from the p-region to produce photons of light. The light emitted by conventional LEDs is monochromatic in appearance, ie this light occurs in one narrow band of wavelengths. The wavelength of the emitted light corresponds to the energy associated with electron-hole pair recombination. In the simplest case, this energy is approximately the band gap energy of the semiconductor where recombination occurs.

Conventional LEDs may additionally include one or more quantum wells at the pn junction that capture both high concentrations of electrons and holes to enhance light generation recombination. Several researchers have attempted to manufacture LED devices that emit white or three-color perceptual light that appears white to the human eye.

Some researchers have reported the intended design or manufacture of LEDs with multiple quantum wells in pn junctions intended to emit light of different wavelengths. The following references may relate to such techniques: US Pat. No. 5,851,905; US Patent No. 6,303,404; US Patent No. 6,504,171; US Patent No. 6,734,467; Damilano et al., Monolithic White Light Emitting Diodes Based on InGaN / GaN Multiple-Quantum Wells, Jpn. J. Appl. Phys. Vol. 40 (2001) pp. L918-L920; Yamada et al., Re-emitting semiconductor construction Free High-Luminous-Efficiency White Light-Emitting Diodes Composed of InGaN Multi-Quantum Well, Jpn. J. Appl. Phys. Vol. 41 (2002) pp. L246-L248]; Dalmasso et al., Injection Dependence of the Electroluminescence Spectra of Re-emitting semiconductor construction Free GaN-Based White Light Emitting Diodes, phys. stat. sol. (a) 192, no. 1, 139-143 (2003).

Some researchers have reported the intended design or manufacture of LED devices that combine two conventional LEDs, intended to emit light of different wavelengths independently, into one device. The following references may relate to such techniques: US Pat. No. 5,851,905; US Patent No. 6,734,467; US Patent Application Publication No. 2002/0041148 A1; US Patent Application Publication No. 2002/0134989 A1; And Luo et al., Patterned three-color ZnCdSe / ZnCdMgSe quantum-well structures for integrated full-color and white light emitters, App. Phys. Letters, vol. 77, no. 26, pp. 4259-4261 (2000).

Some researchers intend to combine a chemical re-emitting semiconductor construction, such as yttrium aluminum garnet (YAG), to a conventional LED element, which is intended to absorb a portion of the light emitted by the LED element and to re-emit a longer wavelength of light. Reported designs or manufacturing. U.S. Patent 5,998,925 and U.S. Patent 6,734,467 may be related to such technology.

Some researchers suggest that I, Al, Cl, Br, Ga or In be used to create a fluorescing center on the substrate that is intended to absorb a portion of the light emitted by the LED element and to re-emitting light of longer wavelengths. Report the intended design or manufacture of LEDs grown on doped ZnSe substrates. US Patent No. 6,337,536 and Japanese Patent Application Publication No. 2004-072047 may be related to such a technique.

US Patent Application Publication No. 2005/0023545 (Camras et al.) Is incorporated herein by reference.

The present invention particularly discloses a light source comprising an LED component having a light emitting surface, the LED component comprising: i) an LED capable of emitting light of a first wavelength; And ii) a second potential well that is not located within the pn junction. The LED and re-emitting semiconductor configuration may be part of one die or chip where the LED is associated with a first potential well located within the pn junction and the re-emitting semiconductor configuration is associated with a second potential well where it is not located within the pn junction. Can be. Alternatively, the LED and re-emitting semiconductor construction may be separate elements, with an optical path provided between one or more other translucent components. The disclosed light source also preferably comprises an optical element having an input surface and an output surface, the input surface being in optical contact with the light emitting surface of the LED component. Such emitting surface may be the surface of an LED or the surface of a re-emitting semiconductor construction, but in many cases it is a relatively high refractive index material, such as a semiconductor material or Si, Ge, GaAs, InP, Sapphire, SiC, ZnSe, etc. Surface of another substrate material. In order to enhance the coupling of light from the LED components, the optical elements also preferably have a relatively high refractive index of at least 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3 or 2.4 at the wavelength of the light emitted by the LED. Have The optical element may be an encapsulant formed in place on the LED component and substantially surrounding the LED component (or portion thereof), or separately manufactured and then in contact with or in proximity to the surface of the LED component. And an “extractor” to combine or extract light from the surface and to reduce the amount of light collected within the component. The extractor or other optical element may have a diverging shape that partially collimates the light focused on the input surface, or a converging shape that directs the light focused on the input surface to the side emission pattern.

In some embodiments, the light source further comprises a patterned low refractive index layer in optical contact with the first portion of the emitting surface and having a first refractive index, the input surface of the optical element being in optical contact with the second portion of the emitting surface, The element has a second index of refraction higher than the first index of refraction. In some embodiments, the light source further comprises reflecting means for totally internally reflecting at least a portion of the light generated by the LED component back to the LED component and in optical contact with the first portion of the emitting surface, wherein the input surface of the optical element comprises It is in optical contact with the second part of the light emitting surface different from the one part. In some embodiments, the optical element comprises a first portion comprising an input surface and composed of a first material, the optical element also comprising a second portion comprising an output surface and composed of a second material, the first material being It has a refractive index larger than that of the second material. In some embodiments, the optical element is one of a plurality of optical elements each having an input surface, the optical element being sized such that the input surfaces are spaced from each other and in optical contact with different portions of the emitting surface.

In some embodiments, the optical element has a bottom, two converging sides and two diverging sides, the bottom being an input surface optically coupled to the light emitting surface. In some embodiments, the optical element is optically coupled to the LED component and is shaped to direct light emitted by the LED component to produce a side emission pattern having two lobes. In some embodiments, the optical element has a bottom, an apex smaller than the bottom, and a converging side extending between the bottom and the vertex, the bottom being optically coupled to the light emitting surface and not larger than the light emitting surface, Induces light emitted by the LED component to produce a side-emitting pattern. In some embodiments, the optical element has a bottom, a vertex, and a converging side that joins the bottom and the vertex, the bottom is optically coupled to the emitting surface, and the optical element comprises a bottom and is comprised of a first material And a second section comprising a vertex and composed of a second material. In some embodiments, the optical element has a first refractive index and has a bottom, a vertex, and a converging side that joins the bottom and the vertex, the bottom is optically coupled to the light emitting surface and is not larger than the light emitting surface, and the light source is an LED Also comprising a second optical element encapsulating the component and the first optical element, the second optical element having a second refractive index lower than the first refractive index. In some embodiments, the optical element has a first index of refraction and has a bottom surface, a vertex portion present on the light emitting surface, and a converging side joining the bottom and the vertex portion, the bottom is optically coupled to the light emitting surface, and the light source is an LED Also comprising a second optical element encapsulating the component and the first optical element, the second optical element having a second refractive index lower than the first refractive index. In some embodiments, the LED component and the second optical element encapsulating the first optical element provide an increase in output extracted from the LED component relative to the output extracted by only the first optical element. In some embodiments, the optical element has a bottom, a vertex, and a side joining the bottom and the vertex, the bottom being optically coupled to the light emitting surface and mechanically separated from the light emitting surface.

Graphic display devices and lighting devices including the disclosed LED elements are also described.

These and other aspects of the present application will be apparent from the detailed description below. In no event, however, should the above summary be construed as limiting the claimed technical subject matter, which technical subject matter is defined solely by the appended claims, which may be amended during the procedure.

In this application,

With respect to the stack of layers of a semiconductor device, "immediately adjacent" means next in sequence without intervening layers, and "close" means next in sequence with one or several intervening layers and "around" (surrounding) means both front and back in order,

"Potential well" means a layer of a semiconductor in a semiconductor device having a conduction band energy lower than the surrounding layer or a valence band energy higher than the surrounding layer, or both,

"Quantum well" typically means a potential well that is sufficiently thin, below 100 nm in thickness, so that the quantization effect raises the electron-hole pair transition energy in the well,

"Transition energy" means electron-hole recombination energy,

A “lattice match” refers to two crystalline materials, such as epitaxial films on a substrate, wherein each material that is separated has a predetermined lattice constant, which is substantially the same, Typically less than 0.2% from each other, more typically less than 0.1% from each other, most typically less than 0.01% from each other,

"Pseudomorphic" refers to a first crystalline layer and a second crystalline layer of a given thickness, such as an epitaxial film and a substrate, wherein each layer that is separated has a predetermined lattice constant, the lattice constant The constants are sufficiently similar, meaning that the first layer of a predetermined thickness can employ the lattice spacing of the second layer in the plane of the layer with virtually no misfit defects.

In any disclosed embodiment that includes n-doped and p-doped semiconductor regions, it should be understood that additional embodiments in which n doping is reversed and vice versa are considered as disclosed herein.

Where each of "potential well", "first potential well", "second potential well", and "third potential well" is mentioned herein, one potential well may be provided, or is typically similar It should be understood that multiple potential wells may be provided that share the characteristics. Likewise, when each of "quantum well", "first quantum well", "second quantum well" and "third quantum well" is referred to herein, one quantum well may be provided, or typically It should be understood that multiple quantum wells can be provided that share similar characteristics.

1 is a planar band diagram of conduction and valence bands of a semiconductor in a configuration (layer thickness not shown to scale).

2 is a graph showing lattice constants and band gap energies for various Group II-VI binary compounds and alloys thereof.

3 is a graph showing a spectrum of light emitted from an element.

4 is a planar band diagram of the conduction and valence bands of a semiconductor in a configuration (layer thickness not shown to scale).

5 and 6 are schematic cross-sectional views of LED packages having a brightness enhancement layer.

7 and 8 are schematic cross-sectional views of additional LED packages having a brightness enhancing layer and a tapered optical element.

9 is a graph showing modeled luminance and luminous output of an LED component as a function of the footprint size of the tapered element on the front emitting surface of the LED component.

10-12 are schematic cross-sectional views illustrating LED packages utilizing composite tapered elements, and FIG. 12 further showing a number of tapered elements coupled to the LED components.

13 is a schematic cross-sectional view of another LED package having a brightness enhancement layer and a plurality of optical elements.

14 is a schematic side view illustrating an optical element and LED component configuration.

15A-15C are perspective views of additional optical elements.

16 is a perspective view of a light source with other optical elements.

17A-17I are plan views of additional optical elements.

18A-18C are schematic front views illustrating alternative optical elements.

19A-19E are schematic side views of additional light sources comprising optical elements and LED components.

20A-20D are bottom views of optical element / LED component combinations.

21 is a perspective view of an optical element and an LED component array.

22 is a partial perspective view of another optical element / LED component combination.

The present application discloses an LED component comprising an LED in combination with a re-emitting semiconductor construction, and an illumination device comprising an optical element in optical contact with or optically coupled to the emitting surface of the LED component. The optical element preferably has a relatively high index of refraction to enhance light coupling from the LED component and is preferably an extractor or extractor, but may also be encapsulant or encapsulant. Typically, the LED may emit light of a first wavelength, and the re-emitting semiconductor construction may absorb light of the first wavelength and re-light light of the second wavelength. The re-emitting semiconductor construction includes a potential well that is not located within the pn junction. The potential wells of the re-emitting semiconductor construction are typically quantum wells but need not be.

In typical operation, the LED emits photons in response to an electric current, and the re-emitting semiconductor construction emits photons in response to absorption of a portion of the photons emitted from the LED. If desired, the re-emitting semiconductor construction can further include an absorbing layer adjacent or immediately adjacent to the potential well. The absorbing layer typically has a band gap energy less than or equal to the energy of the photons emitted by the LED and greater than the transition energy of the potential well (s) of the re-emitting semiconductor construction. In typical operation, the absorber layer aids in the absorption of photons emitted from the LED. The re-emitting semiconductor construction can further include one or more second potential wells that are not located within the pn junction and have a second transition energy that is not equal to the transition energy of the first potential well. In some embodiments, the LED is a UV light emitting LED. In one such embodiment, the re-emitting semiconductor construction comprises one or more first potential wells not located within the pn junction and having a first transition energy corresponding to blue wavelength light and corresponding to green wavelength light not located within the pn junction. One or more second potential wells with a second transition energy and one or more third potential wells with a third transition energy not located within the pn junction and corresponding to red wavelength light.

In some embodiments, the LEDs are visible light emitting LEDs, typically green, blue or purple LEDs, more typically green or blue LEDs, most typically blue LEDs. In one such embodiment, the re-emitting semiconductor construction comprises a pn junction with one or more first potential wells not located within the pn junction and having a first transition energy corresponding to yellow or green wavelength light, more typically green wavelength light. One or more second potential wells not located within and having a second transition energy corresponding to orange or red wavelength light, more typically red wavelength light. The re-emitting semiconductor construction can include additional potential wells and additional absorbing layers.

In some embodiments, the LED has only one pn junction, and the re-emitting semiconductor construction has only one potential well that is not located within the pn junction and has, for example, transition energy corresponding to green wavelength light. In such a case, the LED emits light of a wavelength shorter than green, for example blue, purple or UV wavelengths.

LED and re-emitting semiconductor constructions can be grown using known semiconductor processing techniques in one manufacturing step or process on one wafer, in which case the LED and re-emitting semiconductor constructions are preferably the same material combination, for example Use ZnSe. Alternatively, the LED and re-emitting semiconductor constructions are grown or fabricated in separate processes, and then bonded together with a binder or otherwise, followed by an array of optical elements corresponding to an array of LEDs formed within the optical element or LED wafer. May be diced into individual dies before or after application. In other cases, the LED and re-emitting semiconductor construction may be kept separate, for example, bonded or otherwise coupled to different surfaces of the extractor or other optical element.

Any suitable LED can be used. Elements of the disclosed devices, including LED and re-emitting semiconductor constructions, include Group IV elements such as Si or Ge (in addition to the light emitting layer), III such as InAs, AlAs, GaAs, InP, AlP, GaP, InSb, AlSb, GaSb and their alloys. Group II-VI compounds such as Group V compounds, ZnSe, CdSe, BeSe, MgSe, ZnTe, CdTe, BeTe, MgTe, ZnS, CdS, BeS, MgS and alloys thereof, or alloys of any of the above It may consist of any suitable semiconductor. If appropriate, the semiconductor may be n-doped or p-doped by any suitable method or by the inclusion of any suitable dopant. In a typical embodiment, the LED is a group III-V semiconductor device and the re-emitting semiconductor construction is a group II-VI semiconductor device.

In some embodiments, the composition of the various layers of components of the device, such as LED or re-emitting semiconductor constructions, is selected in view of the following considerations. Each layer can typically be spaced-matched to the substrate or lattice matched to the substrate at a thickness given for this layer. Alternatively, each layer may be free spaced or lattice matched to the immediately adjacent layer. The potential well layer material and thickness are typically selected to provide the desired transition energy, which will correspond to the wavelength of light to be emitted from the quantum well. For example, the points marked 460 nm, 540 nm and 630 nm in FIG. 2 are the lattice constants close to the lattice constants (5.8687 angstroms or 0.58687 nm) for InP substrates, and 460 nm (blue), 540 nm (green) and A Cd (Mg) ZnSe alloy having a band gap energy corresponding to a wavelength of 630 nm (red) is shown. If the potential well layer is thin enough that the transition energy rises above the bulk band gap energy in the well by quantization, this potential well can be considered as a quantum well. The thickness of each quantum well layer determines the amount of quantization energy in the quantum well, which is added to the bulk band gap energy to yield the transition energy in the quantum well. Thus, the wavelength associated with each quantum well can be adjusted by adjusting the quantum well layer thickness. Typically the thickness of the quantum well layer is between 1 nm and 100 nm, more typically between 2 nm and 35 nm. Typically, the quantization energy leads to a wavelength reduction of 20-50 nm for what is predicted based only on band gap energy. Strains in the light emitting layer, including strains resulting from incomplete matching of lattice constants between free space matching layers, can also alter the transition energy for potential wells and quantum wells.

Techniques for calculating the transition energy of modified or unmodified potential wells or quantum wells are known in the art, for example in Herbert Kroemer, Quantum Mechanics for Engineering, Materials Science and Applied Physics (Prentice Hall, Englewood Cliffs, New). Jersey, 1994) at pp. 54 -63; And Zory, ed., Quantum Well Lasers (Academic Press, San Diego, California, 1993) at pp. 72-79, both of which are incorporated herein by reference.

Any suitable emission wavelength can be selected, including emission wavelengths in the infrared, visible and ultraviolet bands. In some embodiments, the emission wavelength is chosen such that the combined output of the light emitted by the device produces an appearance of any color, which color includes white or nearly white, pastel, magenta, cyan, or the like. It can be generated by a combination of three, three or more monochrome light sources. In some embodiments, the device emits light of invisible infrared or ultraviolet wavelengths and light of visible wavelengths as an indication that the device is in operation. Typically, the LED emits photons of the shortest wavelengths so that the photons emitted from the LED have sufficient energy to drive the potential wells in the re-emitting semiconductor construction. In a typical embodiment, the LED is a III-V semiconductor device, such as a blue light emitting GaN-based LED, and the re-emitting semiconductor construction is a II-VI semiconductor device.

1 is a band diagram showing the conduction band and valence band of a semiconductor in a re-emitting semiconductor construction. Layer thickness is not expressed according to scale. Table I shows the composition of the layers 1-9 of this embodiment and the band gap energy (E _g ) for that composition. This configuration can be grown on InP substrates.

Layer 3 represents one potential well that is a red light emitting quantum well having a thickness of about 10 nm. Layer 7 represents one potential well, which is a green light emitting quantum well having a thickness of about 10 nm. Layers 2, 4, 6 and 8 each represent an absorbing layer having a thickness of about 1000 nm. Layers 1, 5 and 9 represent support layers. The support layer is typically selected to be substantially transparent to light emitted from the quantum wells 3 and 7 and short wavelength LEDs. Alternatively, the device may comprise a plurality of red or green light emitting potential wells or quantum wells separated by an absorber layer and / or a support layer.

Without wishing to be bound by theory, it is believed that the embodiment shown in FIG. 1 operates in accordance with the following principles: blue wavelength photons emitted by the LED and impinging on the re-emitting semiconductor construction are absorbed and green light emitting quantum It can be re-emitting as a green wavelength photon from the well 7 or as a red wavelength photon from the red-emitting quantum well 3. Absorption of short wavelength photons produces electron-hole pairs, which can then be recombined within the quantum well to release photons. The multicolor combination of blue, green and red wavelength light emitted from the device may represent white or nearly white. The intensity of the blue, green and red wavelength light emitted from the device can be balanced in any suitable manner including the manipulation of the number of each type of quantum wells, the use of filters or reflective layers, and the manipulation of the thickness and composition of the absorbing layer. . 3 shows the spectrum of light emitted from one embodiment of the device.

Referring back to the embodiment shown in FIG. 1, the absorbing layers 2, 4, 5, 8 are bands for the absorbing layer which are halfway between the energy of photons emitted from the LED and the transition energy of the quantum wells 3, 7. It can be configured to absorb photons emitted from the LED by selecting the gap energy. Electron-hole pairs generated by absorption of photons in absorbing layers 2, 4, 6, 8 are typically captured by quantum wells 3, 7 and then recombined and at the same time emission of photons takes place. The absorbing layer may optionally have a gradient of composition over all or part of their thickness to direct or direct electrons and / or holes towards the potential well. In some embodiments, the LED and re-emitting semiconductor configurations are provided in one semiconductor unit, that is, the LED and re-emitting semiconductor configurations can be grown in a series of manufacturing steps on the same wafer. Such semiconductor units typically comprise a first potential well located in a pn junction and a second potential well not located in a pn junction. These potential wells are typically quantum wells. The unit can emit light of two wavelengths, one of which corresponds to the transition energy of the first potential well (ie, the light emitted by the LED) and the other wavelength of the second potential well ( That is, light emitted by the re-emitting semiconductor construction). In typical operation, the first potential well emits photons in response to a current passing through the pn junction, and the second potential well emits photons in response to absorption of a portion of the photons emitted from the first potential well. The semiconductor unit may further include one or more absorbing layers around or immediately adjacent to or near the second potential well. The absorbing layer typically has a band gap energy less than or equal to the transition energy of the first potential well and greater than the transition energy of the second potential well. In typical operation, the absorbing layer assists in the absorption of photons emitted from the first potential well. The semiconductor unit may include additional potential wells that are located within or not within the pn junction and additional absorber layers.

4 is a band diagram showing the conduction and valence bands of a semiconductor in such a semiconductor unit. Layer thickness is not expressed according to scale. Table II shows the composition of layers 1 to 14 in this example and the band gap energy (E _g ) for that composition.

Layers 10, 11, 12, 13, 14 represent pn junctions or more specifically pin junctions, which are n-doped with intermediate undoped (“native” doped) layers 11, 12, 13. This is because it is interposed between layer 10 and p-doped layer 14. Layer 12 represents one potential well in the pn junction, which is a quantum well with a thickness of about 10 nm. Alternatively, the device can include multiple potential or quantum wells within the pn junction. Layers 4 and 8 represent second and third potential wells that are not within the pn junction, each of which is a quantum well having a thickness of about 10 nm. Alternatively, the device may include additional potential or quantum wells that are not in the pn junction. In a further alternative example, the device may include one potential or quantum well that is not within the pn junction. Layers 3, 5, 7, 9 represent absorbing layers each having a thickness of about 1000 nm. Electrical contacts, not shown, provide a path for supply of current to the pn junction. Electrical contacts are electrically conductive and typically consist of a conductive metal. A positive electrical contact is electrically connected directly to layer 14 or indirectly through an intermediate structure. A negative electrical contact is electrically connected directly to one or more of the layers 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 or indirectly through an intermediate structure.

Without wishing to be bound by theory, it is believed that this embodiment operates in accordance with the following principle: When a current passes from layer 14 to layer 10, the blue wavelength photon is introduced into the quantum well 12 in the pn junction. ) Is released. Photons traveling in the direction of layer 14 may leave the device. Photons traveling in the opposite direction can be absorbed and re-emitted as green wavelength photons from the second quantum well 8 or as red wavelength photons from the third quantum well 4. Absorption of the blue wavelength photons produces electron-hole pairs, which can then recombine within the second or third quantum well to emit photons. Green or red wavelength photons traveling in the direction of layer 14 may leave the device. The multicolor combination of blue, green and red wavelength light emitted from the device may represent white or nearly white. The intensity of the blue, green and red wavelength light emitted from the device can be balanced in any suitable manner including the manipulation of the number of potential wells of each type and the use of filters or reflective layers. 3 shows the spectrum of light emitted from one embodiment of the device.

Referring again to FIG. 4, the absorbing layers 3, 5, 7, 9 may be particularly suitable for absorbing photons emitted from the first quantum well 12, in which the absorbing layers of the first quantum well 12 This is because it has a band gap energy intermediate between the transition energy and the transition energies of the second and third quantum wells 8, 4. Electron-hole pairs generated by absorption of photons in absorbing layers 3, 5, 7, 9 are typically captured by second or third quantum wells 8, 4, then recombined and simultaneously emit photons This happens. The absorber layer can typically be selectively doped like the surrounding layer, which can be n-doped in this embodiment. The absorbing layer may optionally have a gradient of composition over all or part of their thickness to direct or direct electrons and / or holes towards the potential well.

If the LED is a visible wavelength LED, the layer of re-emitting semiconductor construction can be partially transmissive to the light emitted from the LED. Alternatively, if the LED is a UV wavelength LED, for example, one or more of the layers of the re-emitting semiconductor construction may block a large portion or substantially or completely all of the light emitted from the LED, thereby providing a large amount of light emitted from the device. Partially or substantially or completely all of the light is re-emitting light from the re-emitting semiconductor construction. If the LED is a UV wavelength LED, the re-emitting semiconductor construction can include red, green and blue light emitting quantum wells.

The device may comprise additional layers of conductor, semiconductor or non-conductive material. Electrical contact layers can be added to provide a path for supply of current to the LEDs. An electrical contact layer may be disposed so that the current that excites the LED can also pass through the re-emitting semiconductor construction. Alternatively, a portion of the re-emitting semiconductor construction can be etched to form holes or openings through which electrical contacts can be formed in the p or n layers of the LED. A light filtering layer may be added to change or correct the balance of the light wavelengths of the light emitted by the constructed LEDs.

In some embodiments, the disclosed light sources provide white or nearly white light by emitting light at four principal wavelengths in the blue, green, yellow, and red bands. In an alternative embodiment, the light source produces white or nearly white light by emitting light of two major wavelengths in the blue and yellow bands. In another embodiment, the light source emits substantially one visible light color, for example green.

Devices may be active or passive components, such as resistors, diodes, zener diodes, capacitors, transistors, bipolar transistors, FET transistors, MOSFET transistors, insulated gate bipolar transistors, phototransistors, photodetectors, SCRs, thyristors, tris It can include additional semiconductor elements including triacs, voltage regulators, and other circuit elements. The device may comprise an integrated circuit. The device may comprise a display panel or an illumination panel.

(John Wiley & Sons, New York, 1999)]에 설명된 것들을 포함한다. 미국 특허 제5,915,193호(통(Tong) 등) 및 제6,563,133호(통)에 설명된 웨이퍼 접합 방법이 또한 사용될 수 있다. ZnSe에 GaN을 웨이퍼 접합하는 방법은 문헌[Murai et al., Japanese Journal of Applied Physics 43 No. 10A, page L1275 (2004)]에 설명되어 있다. 일부 실시예에서, 접합층은 LED와 재발광 반도체 구성 사이에 존재한다. 접합층은 예를 들어 투명 접착층, 무기 박막, 가융 유리 프릿(frit) 또는 다른 적합한 접합제를 포함할 수 있다. 접합층의 추가 예가 미국 특허 출원 공개 제2005/0023545호(캠라스 등)에 설명되어 있다. 전형적으로, 생성된 결합부(bond)는 투명하다. 접합 방법은 계면 접합, 또는 단지 에지에만 요소(예를 들어, LED 및 재발광 반도체 구성)를 결합하는 기술, 즉 에지 접합을 포함할 수 있다. 선택적으로, 굴절률 정합층 또는 층간 공간(interstitial space)이 포함될 수 있다.LEDs and re-emitting semiconductor constructions included within the disclosed light sources may be prepared by any suitable method that may include molecular beam epitaxy (MBE), chemical vapor deposition, liquid phase epitaxy, and vapor phase epitaxy. Elements of the device can include any suitable substrate. Typical substrate materials include Si, Ge, GaAs, InP, Sapphire, SiC and ZnSe. The substrate may be n-doped, p-doped, or semi-insulating, which may be accomplished by any suitable method or by the inclusion of any suitable dopant. Alternatively, the elements of the device may be free of the substrate. In one embodiment, elements of the device may be formed on a substrate and then separated from the substrate. The elements of the device may also be joined together by any suitable method, including the use of adhesive or welding materials, pressure, heat or a combination thereof. Such a method may be used, for example, to bond an LED (eg, LED die) to a re-emitting semiconductor configuration, to bond the LED to an optical element (eg, an extractor), or to bond the re-emitting semiconductor configuration to an optical element. Can be used. Useful semiconductor wafer bonding techniques are described in chapters 4 and 10 of the text Semiconductor Wafer Bonding. by Q.-Y. Tong and U.

(John Wiley & Sons, New York, 1999). The wafer bonding method described in US Pat. Nos. 5,915,193 (Tong et al.) And 6,563,133 (Tong) can also be used. Methods of wafer bonding GaN to ZnSe are described in Murai et al., Japanese Journal of Applied Physics 43. No. 10A, page L1275 (2004). In some embodiments, the bonding layer is between the LED and the re-emitting semiconductor construction. The bonding layer may comprise, for example, a transparent adhesive layer, an inorganic thin film, a fusible glass frit or other suitable bonding agent. Further examples of bonding layers are described in US Patent Application Publication No. 2005/0023545 (Camras et al.). Typically, the resulting bond is transparent. Bonding methods may include interfacial bonding, or techniques that couple elements (eg, LED and re-emitting semiconductor constructions) only at the edges, ie, edge bonding. Optionally, a refractive index matching layer or interstitial space may be included.

LEDs are typically sold in the form of a package containing an LED die or chip mounted on a metal header. LED dies are LEDs in their most basic form, ie in the form of discrete components or chips manufactured by semiconductor wafer processing procedures. The component or chip may include electrical contacts suitable for applying power to energize the device. Individual layers of components or chips and other functional elements are typically formed on a wafer scale, and the finished wafer is finally diced into individual piece parts to yield multiple LED dies. The metal header has a reflecting cup on which the LED die is mounted and an electrical lead connected to the LED die. The package further includes a molded transparent resin encapsulating the LED die. Encapsulation resins typically have a nominal hemispherical front face that partially collimates light emitted from the LED die. The LED component may be or include an LED die, or an LED die in combination with a re-emitting semiconductor construction or other element.

The aforementioned optical elements can be manufactured separately and then in contact with or in proximity to the surface of the LED component, which can be used to combine or "extract" light therefrom and reduce the amount of light collected within the component. Such elements may be called extractors. The extractor usually has an input face of size and shape that substantially matches the main light emitting face of the LED component.

The extractor can be used to provide a high brightness LED package or light source. As described above or as described in currently pending US patent application Ser. No. 11/009217 or US patent application Ser. No. 11/009241, which is incorporated herein by reference, the LED components of such a package may be used as individual elements or The semiconductor unit may be a combination LED / re-emitting semiconductor construction.

In FIG. 5, the LED package 10 includes LED components 12 mounted on a header or other mount 14. Although LED components and mounts are generally shown for simplicity, it will be appreciated that they may include conventional design features as known in the art and a re-emitting layer as described above. The main light emitting surface 12a, the bottom surface 12b, and the side surface 12c of the LED component are shown in a simple rectangular arrangement, but inclined sides forming other known shapes, for example truncated inverted pyramid shapes. It can also be considered. Electrical contacts to the LED component are also not shown for simplicity, but may be provided on any surface of the LED component as is known. In an exemplary embodiment, the LED component has two contacts all disposed on the bottom surface 12b of the LED component, as in the case of a "flip chip" LED component design. Mount 14 may also function as a support substrate, electrical contacts, heat sinks and / or reflector cups.

The LED package 10 also includes a transparent optical element 16 encapsulating or enclosing the LED component 12. The optical element 16 has a refractive index that is halfway between the LED component (more precisely, the outer portion of the LED component adjacent the light emitting surface 12a) and the refractive index of the ambient medium, which is usually air. In many embodiments, it is desirable to select a material for element 16 where the refractive index is as high as possible but does not substantially exceed the refractive index of the LED component, which means that the difference in refractive index between the LED component and element 16 The smaller it is, the less light is trapped and lost in the LED component. Optical element 16 as shown has a curved output surface, which can help ensure that light is transmitted from the LED package to the surrounding medium and can also at least partially focus the light emitted by the LED component or Can be used to aim. Optical elements having other shapes, including tapered shapes, described further below, may also be used to collimate light. Optical element 16 may be an encapsulant formed in situ on an LED component, in which case it is typically the encapsulant is or comprises a translucent epoxy or silicone.

The LED package 10 further includes a patterned low refractive index layer 18 between the optical element 16 and the LED component, which has the effect of selectively preserving some light collection within the LED component. Enhance the luminance within the opening or region 20 localized at 12a). The patterned low refractive index layer 18 is substantially in optical contact with a portion of the light emitting surface 12a and the side surface 12c except for the opening 20, and the optical element 16 extends over the area of the opening 20. In optical contact with a part of (12a). (In this regard, "optical contact" means that the refractive index characteristic of the low refractive index layer or transparent element controls or substantially affects the total internal reflection (TIR) of at least some of the light propagating within the LED component, for example). Refers to surfaces or media that are sufficiently closely spaced apart, including but not limited to, direct physical contact, typically by a gap of 100, 50, or 25 nm or less, including, for example, having no gaps at all. Are in separate evanescent waves The patterned low refractive index layer 18 has a refractive index substantially lower than both the refractive index of the LED component and the refractive index of the transparent element 16. The layer 18 is It is also optically thick at locations intended to promote light capture, which is why the thickness of the optically thickened attenuated internal frustr large enough to avoid ated total internal reflection, or the refractive index characteristics of the medium on one side of the layer (e.g., optical element 16) in the medium (e.g., LED 12) on the other side of the layer. Means that it does not control or substantially affect the total internal reflection of at least some of the light traveling in. Preferably, the thickness of the patterned low refractive index layer is about 1 / of the wavelength relative to the energy of light of interest in the vacuum. 10, more preferably 1/2, more preferably greater than about 1. The " patterning " of layer 18 also means that layer 18 is continuous across the LED emitting surface but extremely within opening 20 It is meant to include embodiments that are thin (and therefore inefficient to maintain total internal reflection) and that are manufactured optically thick in other locations, where layer 18 is a transparent dielectric material or a layer of such material at the surface of the LED component. It is advantageous to include at least these materials have an advantage over reflective coatings made by simply applying a metal layer to the LED, for example, where the dielectric material is 100% (by TIR) to most of the light in the LED component. Reflections can be provided, while simple metal coatings have substantially less than 100% reflectivity, especially at high incidence angles.

The patterned low refractive index layer 18 reduces the brightness of another portion of the LED (eg, the portion of the light emitting surface 12a beyond the opening 20) and reduces the brightness of the LED (eg, within the opening 20). To improve the brightness of some parts. This effect depends on the LED component having an internal loss low enough to support a large number of bounce reflections of light emitted within the LED component during operation. As advances in LED component manufacturing and design are made, the loss from surface or volume absorption can be expected to be reduced, the internal quantum efficiency can be expected to be increased, and the brightness enhancement effects described herein It can be expected to provide a steadily increasing gain. Bulk absorption can be reduced by improving the substrate and epitaxial deposition process. Surface absorption can be reduced by an improved back reflector, for example by bonding an epitaxial layer to a high reflectivity metal mirror or by including an omnidirectional mirror in the LED structure. Such a design may be more efficient when combined with shaping the back side of the LED component to increase light output through the top side. In an exemplary embodiment, most of the bottom surface 12b is a high reflective material such as a metal or dielectric stack. Preferably, the reflector has a reflectance of greater than 90%, more preferably 95%, most preferably 99% at the LED emission wavelength.

Referring again to FIG. 5, any point light emitting source 22 emits light rays 24, for example. The refractive indices of the LED component 12 and the transparent element 16 are such that the light rays upon the first encounter with the light emitting surface 12a at the LED / optical element interface can be transmitted into and refracted by the element 16. However, the patterned layer 18 changes its interface at that location, causing total internal reflection to the light beam 24. The light beam travels through the thickness of the LED component, reflects off the rear face 12b, and meets the light emitting face 12a again, since there is no layer 18 as shown in FIG. ) To escape into. Thus, the portion of the light emitting surface 12a in the opening 20 becomes brighter at the expense of the portion of the light emitting surface 12a covered by the low refractive index layer 18 (higher luminous flux per unit area and per unit solid angle). ).

In the embodiment of FIG. 5, some light in the LED striking the low refractive index layer 18 is small enough that the angle of incidence to the light emitting surface 12a normal vector is small enough to pass through the low refractive index layer 18 into the element 16. You can still escape. Thus, the light striking the low refractive index coating of the LED component may have an escape angle in the range that is less than zero but less than the uncoated portion. In an alternative embodiment, the low refractive index layer 18 is overcoated with a good vertical incidence reflector, such as a reflective metal or an interference reflector, so as to avoid the loss of the TIR provided by the low refractive index layer 18 without losing the light in the LED component. It is possible to increase recycling and to further improve the brightness at the opening 20. Optionally, an interference reflector may be located between the LED component outer surface and the low refractive index layer 18.

Suitable low refractive index layer 18 includes a coating of magnesium fluoride, calcium fluoride, silica, sol gel, carbon fluoride and silicon. Aerogel materials are also suitable because they can achieve extremely low effective refractive indices of about 1.2 or less, or even about 1.1 or less. Aerogels are prepared by high temperature and pressure critical point drying of gels composed of colloidal silica structural units filled with solvent. The resulting material is a low density microporous medium. Exemplary thicknesses for the low refractive index layer 18 are about 50 to 100,000 nm, preferably about 200 to 2000 nm, depending on the refractive index of the material. The refractive index of layer 18 is lower than the refractive index of optical element 16, which may be a molding resin or other encapsulant material, and lower than the refractive index of that portion of the LED component or LED component adjacent to the emitting surface (s). Preferably, the refractive index of layer 18 is less than about 1.5, more preferably less than 1.4. The low refractive index layer 18 may be a solid layer of dielectric material or a vacuum or gas filled gap between the LED component and the transparent element 16.

The outer surface of the LED component is optically smooth, ie may have a surface roughness R _A of less than about 20 nm. Some, all or part of the exterior LED surface is also optically rough, ie may have a surface roughness R _A greater than about 20 nm. A portion of the edge or top surface may also be at an angle that is not perpendicular to the bottom of the LED component. These angles can range from 0 to 45 degrees from orthogonality. In addition, the major or minor surface of the LED component need not be flat. For example, raised portions or portions of the light emitting surface of the LED component may contact the generally flat bottom surface of the optical element, forming the openings 20, 20a, 34 of at least FIGS. 5-7.

The shape of the opening 20 formed by substantially no low refractive index layer 18 may be circular, rectangular, square, or more complex, whether polygonal or nonpolygonal, orthopedic or atypical. Multiple openings are also contemplated as described in more detail below. The aperture shape (s) can typically be selected as a function of the intended use and can be adapted to optimize overall system performance. Patterning the surface of the opening in a continuous or discontinuous pattern or network of coated low refractive index areas, or providing a low refractive index layer with a thickness or refractive index or both to alter the distribution of light output across the surface of the opening Is also contemplated. The opening may also cover the entire upper emitting surface 12a, where at least a portion of the side 12c is covered with a low refractive index layer.

Referring to FIG. 6, the LED package 10a is shown similar to the LED package 10, but the low refractive index layer 18 is modified by including a network of coated low refractive index regions within the central opening. The modified low refractive index layer is thus labeled 18a and the modified central opening is labeled 20a. Other elements retain the reference numbers used in FIG. 5. As shown, the network of low index regions is arranged in a relatively dense pattern near the edge of the opening so that transmission is relatively low in this region. The ability to adapt transmission through the aperture is useful in high brightness LEDs where specific spatial uniformity or power distribution is required for system design. Likewise, such an arrangement of low refractive index media in the openings can be applied to other disclosed embodiments, including but not limited to the embodiments of FIGS. 7, 8 and 10-12.

The openings can be coated with low refractive index materials having different thicknesses or different refractive indices, or both, for the low refractive index materials (conveniencely referred to as "ambient low refractive index materials") that form the openings. Such design flexibility can be used to alter the angular distribution of light emitted by the packaged LED. For example, coating the opening 20 or 20a with a material having a refractive index between the optical element 16 and the refractive index of the surrounding low refractive index material will limit the range of angles of light emitted by the opening. This usually allows light to be emitted at large angles to be regenerated in the LED component and increases the output of light in an angular range that can be used more efficiently by the associated optical system. For example, the focusing optics used in the electronic projection system do not efficiently use light outside of the commonly used F / 2 to F / 2.5 acceptance design angle.

Referring now to FIG. 7, the LED package 30 is in optical contact with the LED component 12 partially and transparently spaced apart from the LED component to form a substantial air gap 34 therebetween. ). The transparent element 32 has an input face 32a and an output face 32b, the input face 32a being smaller than the output face 32b, smaller than the light emitting face 12a of the LED component, and part of the light emitting face. In optical contact with the opening 34. In this regard, the input face is "small" than the output face because it has a smaller surface area, and thus the output face is larger than the input face because it has a larger surface area. The difference in shape between the optical element 32 and the light emitting surface 12a creates an air gap 36, which forms a pattern of low refractive index around the contact area (opening 34). Thus, light generated by the LED component can be efficiently extracted from the opening 34 by the transparent element 32 at high brightness. Optical element 32 and other optical elements disclosed herein may be bonded to the LED component at the point of contact by any suitable means, or may be held in place without being bonded to the LED component emitting surface. Further description of non-junction optical elements in LED packages is hereby incorporated by reference in its entirety and is commonly referred to in the US as "LED Package With Non-Bonded Optical Element" and is commonly assigned. Patent Application Publication 2006/0091784 (Connor et al.). As noted above, the angular range of light emitted by the LED emitting surface 12a over the opening 34 into the optical element 32 is a material whose refractive index is between the refractive indices of the LED component 12 and the transparent element 32. It can be reduced by interposing the layer.

Another approach is to use a transparent element with one or more tapered sidewalls as shown in FIG. 8 to reduce the angular range of the collected light—or to collimate (at least partially) the collected light. Here, the LED package 40 is similar to the LED package 30, but the optical element 42 is replaced with the optical element 32. Element 42 has an input face 42a and an output face 42b, the input face 42a being smaller than the output face 42b, smaller than the light emitting face 12a of the LED component, and having a portion of the light emitting face. The optical contact is made to form the opening 44. The difference in shape between the optical element 42 and the light emitting surface 12a creates an air gap 46, which forms a pattern of low refractive index around the contact area (opening 44). Moreover, the optical element 42 includes tapered sides 42c and 42d, which are reflective to collimate some of the very inclined light entering the input face 42a from the LED component. The reflectances of the sides 42c and 42d may be provided by a low refractive index medium supporting the TIR, or by the application of a reflective material, for example a metal layer or an interference reflector, or a combination thereof.

Optical element 42 may be formed through a fluid, thermally bound inorganic glass, plastic inorganic glass, or an optically smooth finish (surface roughness R less than about 50 nm, preferably less than about 20 nm. _A )) may be in optical contact with the emitting surface of the LED component by providing a surface and then keeping these surfaces adjacent to each other. Moreover, the optical element 42 is formed separately from the lenticular top comprising a surface 42b with a tapered bottom comprising surfaces 42a, 42c, 42d, these two parts being joined together by conventional means. It may be a complex of structures attached or otherwise bonded. Broken lines are provided to more clearly show the two parts. Further description of the composite optical element, design considerations and related advantages is provided below.

The model was used to determine a possible brightness increase for a packaged LED using a tapered optical element coupled to the patterned low refractive index layer and the output aperture. The LED die was modeled to have the material properties of silicon carbide (refractive index 1.55), for example, with a light emitting area, an absorbing area, and a sloped edge facet, to represent the optical behavior of a typical LED die. A truncated inverted pyramid tapered optical element was optically coupled to the front or light emitting surface of the LED die. The material property of the optical element is the material property of silicon carbide. The LED die had a square shape when viewed from the front as the input and output surfaces of the optical element were such. The model further combined the output face of the optical element to a hemispherical lens with the material properties of BK7 glass, where the diameter of the lens was 10 times the width of the square LED die light emitting surface, and the radius of curvature of the lens was 5 times the width. The aspect ratio, i.e. the height of the optical element is maintained at 2.2 times the width of the output surface of the optical element and the width of the output surface is maintained at twice the width of the input surface, while the size of the input surface of the optical element is LED die emitting Incrementally changed from 100% of the area to 4%. As the size of the optical element becomes smaller than the size of the LED die emitting surface, a medium with a refractive index of 1 covers a portion of the LED die emitting surface outside the optical element input surface, thus complementing the LED die in a manner complementary to the optical element input surface. It is assumed to form a patterned low refractive index layer covering the light emitting surface. Fractional output emitted by the optical element (indicative of the relative luminous output of the LED package) and relative irradiance (lumen / (cm 2 sr)) emitted by the output surface of the optical element (indicative of the relative luminance of the LED package) ) Was calculated. 9 shows the observed trend in a general manner. Curve 50 is the emitted relative fractional output and curve 52 is the relative irradiance. The results support that as the aperture size decreases, less overall luminous output is obtained from the package, but the luminance (in the smaller aperture) can be significantly increased.

Similar results for the model indicate that a light source configuration using an LED die in combination with an LED component, ie a re-emitting semiconductor configuration, for example a re-emitting semiconductor configuration, is placed on top of the LED die and an optical element (e. Is expected for a light source arrangement disposed above the re-emitting semiconductor construction, ie optically coupled to the emitting surface of the LED component.

The patterned low refractive index layer of the disclosed embodiments can include a coating of low refractive index material applied to a gap or LED component. Suitable methods of coating the LED component with a low refractive index material of liquid—or with a separate layer capable of forming an indirect reflector— include spin coating, spray coating, dip coating, and dispensing the coating on the LED component. . The liquid coating may consist of monomers, solvents, polymers, inorganic glass molding materials, sol gels, and aerogels that are subsequently cured. Suitable methods of coating the low refractive index material in the gaseous state include chemical vapor deposition or condensing vapor on the LED component. LED components may also be coated with low refractive index materials by sputtering, vapor deposition, or other conventional physical vapor deposition methods.

Coating is applied to multiple LEDs at the wafer level (before dicing) or after the wafer is diced but before being mounted, after the LED component is mounted on a header or other support, and after electrical connection is made to the LED component. Can be applied. The coating may also be applied after bonding the re-emitting semiconductor construction wafer to an LED wafer comprising an array of individual LEDs. The opening can be formed before or after the low refractive index coating is applied. The choice of post-coating patterning method may depend on the compatibility with the particular low refractive index material (s) and semiconductor processing selected. For example, the wafer may be covered with photoresist and patterned to create holes requiring openings, suitable low refractive index coatings may be deposited, and then liftoff may be performed using a suitable solvent. Alternatively, the low refractive index material may be deposited first over the entire wafer or LED component, the patterned photoresist layer may be applied as an etch mask and the low refractive index material may be removed using a suitable technique such as reactive ion etching. have. The photoresist layer may be selectively peeled off using a suitable solvent. Other techniques for patterning low refractive index materials include laser ablation and shadow masking, which can be particularly useful for materials that can be dissolved in typical photolithographic stripping or developing solvents. Suitable methods of lifting off the unwanted coating from the low adhesion area include first applying the bonding material and then removing the bonding material, where the bonding material may remove the coating from the opening area but the surrounding coating may remain intact. To be. Low refractive index coatings can also be patterned to form areas in which electrical connections can be made to the LED components. See, eg, US Patent Application Publication No. 2003/0111667 A1 (Schubert), which is incorporated herein by reference.

Metal reflective layers can be applied by conventional processes and patterned as needed to provide openings and proper electrical insulation.

Referring now to FIG. 10, an LED package 60 is shown that uses a tapered optical element 62 to combine light from LED component 12. As discussed in connection with the optical element 42 of FIG. 8, the optical element 62 also has a composite configuration, ie includes two or more sections 64, 66 joined together. These sections have input faces 64a, 66a, output faces 64b, 66b and reflective sides 64c, 64d, 66c, 66d as shown. The tapered side of the element 62 redirects or collimates (at least partially) the light from the LED emitting surface 12a located in a non-imaging manner. For tapered element 62 and other tapered elements disclosed herein, the sides need not be planar. These aspects may be conical, curved (including parabola) or any suitable combination depending on the intended use and design constraints. The tapered element disclosed may have the shape of an element known in the art as a CPC (“composite” parabolic concentrator).

In many situations, the tapered optical element is formed of a high refractive index material to reduce reflection at the LED emitting surface 12a across the opening formed by the input surface 64a so that light is more efficiently emitted from the LED component 12. It is desirable to combine or extract. In many situations it is also desirable to manufacture optical elements using materials having high thermal conductivity and high thermal stability. In this way, the optical element can perform not only an optical function but also a thermal management function. In addition, U.S. Patent Application Publication No. 2006/0091414 (Oderkirk), which is incorporated herein by reference in its entirety and is commonly assigned to " LED Package With Front Surface Heat Extractor " As described in more detail in (Ouderkirk et al.), Thermal management benefits can be obtained by thermally coupling such optical elements to a heat sink.

Unfortunately, transparent materials with sufficiently high refractive indices at LED emission wavelengths, for example greater than about 1.8, 2.0 or even 2.5 and / or greater than about 0.2 W / cm / K thermal conductivity, are expensive and / or difficult to manufacture. There is a tendency. Materials with both high refractive index and high thermal conductivity include diamond, silicon carbide (SiC) and sapphire (Al ₂ O ₃ ). These inorganic materials are expensive, physically very hard, and difficult to shape or polish to an optical grade finish. Silicon carbide also exhibits a type of defect called a micropipe, which can lead in particular to scattering of light. Silicon carbide is also electrically conductive, thereby providing electrical contact or circuit functionality as well. Scattering in the tapered optical element may be allowed if the scattering is limited to a position adjacent the input end of the element. However, fabricating tapered elements with a length sufficient to efficiently combine light from the LED components can be costly and time consuming. An additional challenge in manufacturing a one-piece tapered element is that the material yield can be relatively low and that the form factor allows the LED component to be assembled separately with the tapered element. For this reason, it may be advantageous to divide the tapered element into two or more sections made of different optical materials to reduce manufacturing costs.

The first section is preferably in optical contact with the LED component and has a first optic having a high refractive index (preferably approximately equal to the LED component refractive index at the light emitting surface), high thermal conductivity, and / or high thermal stability. Are made of materials. In this regard, high thermal stability refers to materials having a decomposition temperature of about 600 ° C. or higher.

The second section is coupled to the first section and is made of a second optical material, which can be made easier than the first optical material with a low material cost. The second optical material may have a lower refractive index, lower thermal conductivity, or both as compared to the first optical material. For example, the second optical material may include glass, polymers, ceramics, ceramic nanoparticle filled polymers, and other optically transparent materials. Suitable glasses include those comprising oxides of lead, zirconium, titanium and barium. The glass can be made from compounds comprising titanate, zirconate and tartarate. Suitable ceramic nanoparticles include zirconia, titania, zinc oxide and zinc sulfide.

A third section comprised of a third optical material may be coupled to the second section to further assist in coupling the LED light to the external environment. In one embodiment, the refractive indices of the three sections are arranged such that n ₁ > n ₂ > n ₃ to minimize the overall Fresnel surface reflection associated with the tapered element.

Very large lens elements such as the top of the optical element 42 shown in FIG. 8 may advantageously be located or formed at the output end of the disclosed simple or composite taper element. Antireflective coatings may also be provided on the input and output surfaces of the disclosed optical elements, including the surface (s) and / or taper elements or other collimating elements of such lens elements.

In an exemplary arrangement, the LED die may include a 1 mm x 1 mm GaN junction on a 0.4 mm thick slab of SiC. The first section 64 of the tapered element 62 may be composed of SiC. The second section 66 may be composed of a nonabsorbing non-scattering high refractive index LASF35 glass with n = 2.0. The width dimension of the junction between the first and second sections and the output dimension of the second section can be selected as desired to optimize the overall light output into the ambient environment with a refractive index of 1.0. The edge of the 0.4 mm thick SiC slab can be tapered with a 12 degree negative slope to completely attenuate the TIR mode of light reflection on the side of the LED component. This slope can be adapted as desired because absorption and scattering in the LED junction and SiC slab can alter the integrated mode structure compared to standard encapsulated LEDs. For example, it may be desirable to use a positive slope (if the width of the LED junction is less than the width of the SiC slab) to induce the optical mode away from the absorbing junction. SiC slabs can be considered as part of the tapered element in this way.

The first section 64 can be coupled to the heat sink as described above. The second section 66 may be bonded to the first section 64 using conventional bonding techniques. If a bonding material is used, it may have a predetermined refractive index between the two optical materials that are joined to reduce Fresnel reflections. Other useful bonding techniques include wafer bonding techniques known in the semiconductor wafer bonding art. Useful semiconductor wafer bonding techniques include those described above.

In the LED package 70 shown in FIG. 11, the first section 74 is encapsulated in the second section 76, with the tapered reflective sidewalls connecting the input face 74a to the larger output face 74b. The second section also utilizes a composite taper element 72 having an input face 76a (in the same space as the output face 74b) and even much larger output face 76b. The output face 76a is curved to provide the composite element 72 with light output useful for further collimation or focusing. The tapered side of the section 74 is shown having a coating 78 of low refractive index material to promote TIR at such a surface. The material preferably has a refractive index lower than the refractive indices of the first section 74, the second section 76, and the LED component 12. Such a coating 78 may also be applied to a portion of the light emitting surface 12a that is not in contact with the section 74 and / or to the side 12c (see FIG. 5) of the LED component 12. In the construction of the LED package 70, the first section 74 may be coupled to (or simply placed over) the desired opening area of the emitting surface 12a, and the precursor liquid encapsulating material is metered in a sufficient amount The LED component and the first section can be encapsulated, and then the precursor material is cured to form the finished second section 76. Suitable materials for this purpose include conventional encapsulation formulations such as silicone or epoxy materials. The package may also include a heat sink coupled to the side of the first section 76 through the coating 78. Even without such a heat sink, the use of the high thermal conductivity first section of the tapered element adds significant thermal mass to the LED component, providing a slight advantage for at least pulsed operation using modulated drive currents. Can provide.

Both simple and complex tapered elements disclosed herein can be made by conventional means, for example by separately manufacturing tapered components, bonding the first segment to the LED component, and then adding subsequent segments. . Alternatively, simple and complex tapered elements are US Patent Application Publication No. 2006/0094340 (Oderkirk et al.), Entitled " Process For Manufacturing Optical And Semiconductor Elements " ) And U.S. Patent Application Publication No. 2006/0094322 (Oderkirk et al.) Entitled "Process For Manufacturing A Light Emitting Array", Both of these patent application publications are incorporated herein by reference in their entirety. In summary, a workpiece is prepared that includes one or more layers of the desired optical material. The workpiece can be in a large format such as a wafer or fiber segment. Subsequently, the finely patterned abrasive is brought into contact with the workpiece to polish the channel in the workpiece. When polishing is complete, the channel forms a number of protrusions that may be in the form of simple or complex tapered elements. The tapered elements can be individually removed from the workpiece and bonded to separate LED components one by one, or the array of tapered elements can be conveniently bonded to the array of LED components.

Furthermore, optical elements such as extractors may be manufactured using the techniques described in US Patent Application No. 11 / 381,512, filed May 3, 2006 (Agency Control Number: 62114US002), May 2006 It can be made using the high refractive index material disclosed in US Patent No. 11 / 381,518 (Representative Control No. 61216US002), filed on 3rd, and assigned in its entirety, both of which are hereby incorporated by reference. .

When a light coupling element whose input surface is smaller than the light emitting surface of the LED component is used, it becomes possible to consider combining a number of such elements in different parts of the same light emitting surface.

Advantageously, such an approach can be used to reduce the amount of optical material needed to combine a given amount of light from the LED component by simply replacing one tapered optical element with a plurality of smaller optical elements. have. Differences in material usage can be particularly important when dealing with expensive and difficult materials such as diamond, SiC and sapphire. For example, replacing one tapered optical element with a 2x2 array of smaller tapered optical elements can reduce the required thickness for high refractive index (first) optical material by more than twice, and a 3x3 array More than three times the required thickness can be reduced. Surprisingly, although light may not be efficiently emitted from the LED in place between the input faces of the optical element, modeling indicates that this approach still has a very high overall extraction efficiency.

Another advantage of using multiple light coupling elements such as tapered elements is that gaps or spaces are formed between the elements that can be used for various purposes. For example, the gap or space can be filled with high refractive index fluids, metal thermal conductors, electrical conductors, heat transfer fluids, and combinations thereof.

Modeling was carried out for an LED package consisting of an absorbent layer and SiC with an adjusted layer such that 30% of the light generated in the LED die emitted from the LED when immersed in a medium having a refractive index of 1.52. This represents a typical LED device. The model used a 3x3 array of tapered optical elements coupled to the LED emitting surface as shown in LED package 80 of FIG. The LED die 12 ′ shown here has an inclined side 12c ′ and a front emitting surface 12a ′, with the three tapered optical elements 82, 84, 86 being respectively input faces 82a, 84a. 86a) is shown coupled to the front emitting surface. It should be noted that spaces or gaps 83 and 85 have been formed between the small optical elements. Output faces 82b, 84b, 86b are coupled to the input face 88a of the tapered large optical element 88, which has an output face 88b. The model also used a hemispherical lens (not shown) with a very large size for the tapered element 88, with the plane of the hemispherical lens attached to the output face 88b and the lens with BK7 glass (n = 1.52). Was prepared. Tapered element 88 was modeled as consisting of LAS35 (n = about 2). The model was then evaluated for different optical materials for small tapered elements and different materials for the surrounding space surrounding the LED components, including gaps 83 and 85.

The calculated output power (for example, in watts) of the modeled LED package is a function of the optical material of the tapered element (shown as "A" in the table) and the surrounding material (shown as "B" in Table III) as shown below: to be.

When these values are normalized to the power output of the system using one SiC taper element instead of a 3x3 array of smaller elements, the following results are obtained (Table IV):

Tables III and IV show that the tapered optical elements do not need to be optically coupled over the entire area of the LED emitting surface to extract light efficiently. These tables also show that the surrounding volume between the small tapered elements can have a low refractive index without causing a significant reduction in extraction efficiency. Similar results are expected for light sources that use LED components, including both LED and re-emitting semiconductor constructions.

The ambient volume can be filled with a certain material to increase the extraction efficiency. The filler material may be a fluid, organic or inorganic polymer, inorganic particle filled polymer, salt or glass. Suitable inorganic particles include zirconia, titania and zinc sulfide. Suitable organic fluids include any that are stable at the LED operating temperature and against the light generated by the LED. In some cases, the fluid should also have low electrical conductivity and ion concentration. Suitable fluids include water, halogenated hydrocarbons, and aromatic and heterocyclic hydrocarbons. The filler material may also function to bond the tapered optical element to the LED component.

At least a portion of the space between the optical elements may have a metal applied for distributing current to the LED component, removing heat from the LED component, or both. Since the metal has a measurable light absorption, it may be desirable to minimize absorption losses. This can be done by minimizing the contact area of the LED component with the metal and reducing light coupling to the metal by introducing a low refractive index material between the LED component surface, the optical element, or both and the metal. For example, the contact area can be patterned into an array of metal contacts surrounded by a low refractive index material in electrical conduction with the top metal layer. See, for example, the '667 Schubert patent publication mentioned above. Suitable low refractive index materials include fluorocarbons, water, and hydrocarbons, such as fluorinert, available from 3M Company, St. Paul, Minn., USA, in gas or vacuum. The metal may extend into the medium surrounding the optical element, where heat may be removed.

Fluid can also be provided between the tapered elements to remove additional heat. The array of tapered optical elements can be a square array (eg, 2x2, 3x3, etc.), a rectangular array (eg, 2x3, 2x4, etc.), or a hexagonal array. The tapered individual optical elements can be square, rectangular, triangular, circular, or other desired cross-sectional shape at their input or output surfaces. The array may extend over the entire light emitting surface of the LED, over or over a portion thereof, or only over a portion thereof. LEDs with low softening temperature solder glass, soft inorganic coatings such as zinc sulfide, high refractive index fluids, polymers, ceramic filled polymers, or to provide optical elements and LEDs with very smooth and flat surfaces and to the input surface of the optical element By mechanically holding the component, the tapered element can be attached to the LED emitting surface.

Another LED package 90 having a number of optical elements 92, 94 and a patterned low refractive index layer 96 is shown in FIG. 13. The patterned low refractive index layer 96 includes two openings, as shown, with optical elements 92 and 94 disposed thereon in optical contact with the light emitting surface 12a of the LED component. Layer 96 is also in optical contact with LED component emitting surface 12a as well as LED component side 12c. The LED package 90 further includes a metal contact 98 shown over a portion of the low refractive index layer 96. Although not shown in FIG. 13, the patterned layer 96 is also patterned in the vicinity of the metal contact 98, and the metal contact 98 preferably extends through the hole in the layer 96 to extend the LED component 12. Provides electrical contact to A second electrical contact can be provided at another location on the LED component, depending on the chip design.

Extractors and other optical elements useful in the disclosed light sources can have a wide variety of shapes, sizes, and configurations. For example, converging optical elements have also been found to be useful for efficiently extracting light from LED components and to alter the angular distribution of emitted light. As described above or as described in currently pending US patent application Ser. No. 11/009217 or US patent application Ser. No. 11/009241, which is incorporated herein by reference, the LED components of such a package may be used as individual elements or The semiconductor unit may be a combination LED / re-emitting semiconductor construction.

The optical element can efficiently extract light from the LED component and change the angular distribution of the emitted light. Each optical element is optically coupled to the light emitting surface of the LED component (or LED component array) to efficiently extract light and change the light emission pattern of the emitted light. LED light sources comprising optical elements may be useful in a variety of applications, including, for example, backlights of liquid crystal displays or backlit signs.

Light sources comprising the converging optical elements described herein may be suitable for use in backlights of both configurations, edge and direct. Wedge-shaped optical elements are particularly suitable for edge type backlights where the light source is disposed along the outside of the backlight. Pyramid or conical converging optical elements may be particularly suitable for use in direct backlights. Such light sources can be used as a single light source element or arranged in an array, depending on the particular backlight design.

In the case of a direct backlight, the light source is generally disposed between the diffuse reflector or mirror reflector and the top film stack, which may include a prism film, a diffuser and a reflective polarizer. These can be used to direct light emitted from the light source towards the viewer in the most useful viewing angle range and with uniform brightness. Exemplary prism films include brightness enhancing films such as BEF ™ available from 3M Company, St. Paul, Minnesota, USA. Exemplary reflective polarizers include DBEF ™, also available from 3M Company, St. Paul, Minn. For edge type backlights, the light source can be positioned to inject light into the hollow or solid light guide. The light guide generally has a reflector underneath and a top film stack as described above.

14 is a schematic side view illustrating a light source according to an embodiment. The light source includes an optical element 99 and an LED component 12. The optical element 99 has a triangular cross section with a bottom surface 120 and two converging sides 140 that are coupled opposite to the bottom surface 120 to form a vertex 130. The apex may be a point as shown at 130 in FIG. 14, and may be blunt, for example as in a truncated triangle (shown as dashed line 135). The blunt apex can be flat, rounded, or a combination thereof. The vertex is smaller than the base and preferably above the base. In some embodiments, the vertices are no more than 20% of the base size. Preferably, the vertex is 10% or less of the base size. In FIG. 14, the vertex 130 is centered over the bottom 120. However, embodiments are also contemplated where the vertices are not centered or deviate away from the center of the base.

The optical element 99 is optically coupled to (or in optical contact with) the LED component 12 to extract light emitted by the LED component 12. The main emitting surface 12a of the LED component 12 is substantially parallel and proximate to the underside 120 of the optical element 99. LED component 12 and optical element 99 may be optically coupled in a number of ways, including bonded and non-bonded configurations, described in more detail below.

Converging sides 140a and 140b of optical element 99 operate to change the light emission pattern of light emitted by LED component 12 as shown by arrows 160a and 160b in FIG. 14. Exposed typical LED components emit light in a first light emitting pattern. Typically, the first emissive pattern is generally forward emissive or has substantially front emissive components. Converging optical elements, such as optical element 99 shown in FIG. 14, change the first light emitting pattern to a different second light emitting pattern. For example, the wedge-shaped optical element induces light emitted by the LED component to produce a side emission pattern with two lobes. FIG. 14 shows exemplary light rays 160a and 160b emitted by the LED component, which enters the optical element 99 from the underside. Light rays emitted in a direction forming a relatively small angle of incidence with the converging side 140a will be refracted as they exit the high refractive index material of the optical element 20 and enter the surrounding medium (eg, air). Exemplary light ray 160a shows one such light ray incident at a small angle to the normal. Other light rays that are emitted at a large angle of incidence, ie at an angle above the critical angle, will be totally internally reflected at the first converging side 140a that they encounter. However, for a converging optical element such as illustrated in FIG. 14, the reflected light beam will then encounter the second converging side 140b at a small angle of incidence, where it will be refracted and exit the optical element. Exemplary ray 160b illustrates one such light path.

An optical element having at least one converging side can change the first light emitting pattern to a different second light emitting pattern. For example, the general forward emitting light pattern may be changed to the second general side emitting light pattern using such a converging optical element. In other words, the high refractive index optical element can be shaped to induce light emitted by the LED component to produce a side emission pattern. If the optical element is rotationally symmetrical (eg, shaped as a cone), the resulting light emission pattern will have a toroidal distribution and the intensity of the emitted light will be concentrated in a circular pattern around the optical element. If, for example, the optical element is shaped into a wedge (see, eg, FIG. 16), the side emission pattern will have two lobes, and the light intensity will be concentrated in two zones. In the case of a symmetrical wedge, two lobes will be located on opposite sides (two opposed zones) of the optical element. For optical elements having a plurality of converging sides, the side emitting pattern will have a corresponding plurality of lobes. For example, for an optical element shaped as a four-sided pyramid, the resulting side emitting pattern will have four lobes. The side emitting pattern can be symmetrical or asymmetrical. An asymmetric pattern will be produced when the vertices of the optical element are arranged asymmetrically with respect to the base or emitting surface. Those skilled in the art will understand various permutations of such arrangements and shapes that produce a variety of different emission patterns as desired.

In some embodiments, the side emission pattern has an intensity distribution with a maximum at polar angle of at least 30 ° as measured in the intensity line diagram. In another embodiment, the side emission pattern has an intensity distribution centered at an angle of at least 30 °. Other intensity distributions are also possible with the optical elements currently disclosed, including, for example, having and / or centered at maximum at 45 ° and 60 ° polar angles.

The converging optical element can take various forms. Each optical element has a bottom, a vertex and at least one converging side. The base can have any shape (eg, square, circular, symmetrical or asymmetrical, regular or irregular). Vertices may be points, lines or surfaces (for blunt vertices). Regardless of the particular converging shape, the vertex has a smaller surface area than the base, so that the side (s) converge from the bottom toward the vertex. Converging optical elements can be shaped as pyramids, cones, wedges, or a combination thereof. Each of these shapes can also be truncated near the vertex to form a blunt vertex. The converging optical element may have a polyhedron shape with a polygonal base and at least two converging sides. For example, a pyramidal or wedge shaped optical element may have a rectangular or square bottom and four sides with at least two converging sides. The other side may be a parallel side or alternatively may diverge or converge. The shape of the base need not be symmetrical and can be shaped, for example, as a trapezoid, parallelogram, quadrilateral or other polygon. In other embodiments, the converging optical element may be circular, oval or irregularly shaped but have a continuous base. In these embodiments, the optical element can be said to have a single converging side. For example, an optical element with a circular base can be shaped as a cone. In general, the converging optical element includes a bottom, (at least partially) a vertex on the bottom, and one or more converging sides that connect the vertex and the bottom to complete the solid.

FIG. 15A shows one embodiment of a converging optical element 200 shaped as a four-sided pyramid having a base 220, a vertex 230, and four sides 240. In this specific embodiment, the bottom surface 220 may be rectangular or square, and the vertex portion 230 is centered on the bottom surface (projection of the vertex portion to the line 210 perpendicular to the plane of the bottom surface is the bottom surface 220). Centered above). 15A also shows an LED component 12 having an emitting surface 12a adjacent and parallel to the underside 220 of the optical element 200. LED component 12 and optical element 200 are optically coupled at the emitting surface-base interface. Optical coupling can be achieved in several ways, described in more detail below. For example, LED components and optical elements can be bonded together. In FIG. 15A the bottom and the emitting surface of the LED component are shown to substantially match in size. In other embodiments, the bottom may be larger or smaller than the LED component emitting surface.

15B illustrates another embodiment of the converging optical element 202. Here, the optical element 202 has a hexagonal bottom 222, a blunt apex 232, and six sides 242. The sides extend between the base and the vertex, and each side converges toward the vertex 232. The apex 232 is blunt and also forms a surface shaped as a hexagon that is hexagonal but smaller than the hexagonal base.

FIG. 15C shows another embodiment of an optical element 204 having two converging sides 244, a bottom 224, and a vertex 234. In FIG. 15C, the optical element is shaped as a wedge and the vertex 234 forms a line. The other two sides are shown as parallel sides. The optical element 204 when viewed from above is shown in FIG. 17D.

An alternative embodiment of the wedge-shaped optical element also includes a shape having a combination of converging and diverging sides, such as the optical element 206 shown in FIG. 16. In the embodiment of FIG. 16, the wedge-shaped optical element 206 is similar to an axe-head. The two diverging sides 142 operate to collimate the light emitted by the LED components. The two converging sides 144 are above the bottom when viewed from the side (see FIG. 14), but the vertices shaped as lines having a portion extending beyond the bottom when viewed as shown in FIG. 16 (or FIG. 17E) ( Converge to the top forming 132. The converging side 144 allows the light emitted by the LED component 12 to be turned sideways as shown in FIG. 14. Another embodiment includes a wedge shape in which all sides converge, for example as shown in FIG. 17F.

The optical element may also be shaped as a cone with a circular or elliptical bottom, a vertex over (at least partially) the bottom, and one converging side connecting the bottom and the vertex. As in the pyramid and wedge shapes described above, the vertices may be points, lines (straight or curved), or they may be blunt to form a surface.

17A-17I show plan views of some alternative embodiments of optical elements. 17A-17F illustrate an embodiment where the vertex is centered on the underside. 17G-17I illustrate an embodiment of an asymmetric optical element in which the vertex is deviated or tilted relative to the base and not centered on the base.

FIG. 17A shows a pyramidal optical element with a square bottom, four sides, and a blunt vertex 230a centered over the bottom. FIG. 17H shows a pyramidal optical element with a square bottom, four sides and blunt vertices 230h off center. FIG. 17B shows an embodiment of an optical element with a square bottom and a blunt vertex 230b shaped as a circle. In this case, the converging side is curved such that the square base is connected with the circular vertex. FIG. 17C shows a pyramidal optical element having a square bottom, four triangular sides converging at points to form a vertex portion 230c centered over the bottom. FIG. 17I shows a pyramidal optical element having a square underside, four triangular sides that converge at a point to form a vertex portion 230i that is off-top (not centered).

17D-17G illustrate wedge-shaped optical elements. In FIG. 17D, apex 230d forms a line above and centered on the bottom surface. In FIG. 17E, apex 230e forms a line centered over the bottom and partially above the bottom. The vertex portion 230e also has portions extending beyond the bottom surface. The top view shown in FIG. 17E may be the top view of the optical element shown in perspective view in FIG. 16 and described above. 17F and 17G show two alternative embodiments of a wedge-shaped optical element having four abutting sides and a vertex forming a line. In FIG. 17F, the vertex portion 230f is centered on the bottom surface, while in FIG. 17G, the vertex portion 230g is deflected.

18A-18C show side views of optical elements according to alternative embodiments. 18A illustrates one embodiment of an optical element having a bottom 350 and sides 340 and 341 starting at bottom 350 and converging toward a vertex 330 above the bottom 350. Optionally, the sides may converge towards the blunt apex 331. 18B shows another embodiment of an optical element having a bottom 352, a converging side 344 and a side 342 perpendicular to the bottom. Two sides 342 and 344 form a vertex 332 over the edge of the base. Optionally, the vertex can be a blunt vertex 333. 18C shows a side view of an alternative optical element having a generally triangular cross section. Here, the bottom surface 325 and the side surfaces 345 and 347 generally form a triangle, while the side surfaces 345 and 347 are non-planar surfaces. In FIG. 18C, the optical element has a curved left side 345 and a faceted right side (ie, a combination of three smaller flat portions 347a-347c). The sides may be curved, divided, faceted, convex, concave or a combination thereof. Aspects of that type still function to alter the angular emission of the extracted light, similar to the planar or flat surfaces described above, but provide an increased degree of customization of the final light emission pattern.

19A-19E illustrate alternative embodiments of optical elements 420a-420e having non-planar sides 440a-440e extending between respective bottoms 422a-422e and vertices 430a-430e, respectively. Illustrated. In FIG. 19A, the optical element 420a has a side 440a that includes two faceted portions 441a and 442a. Portion 442a near base 422a is perpendicular to bottom 422a, while portion 441a converges toward apex 430a. Similarly, in FIGS. 19B and 19C, optical elements 420b and 420c have sides 440b and 440c formed by connecting two portions 441b and 441c, 442b and 442c, respectively. In Fig. 19B, the converging portion 441b is concave. In Fig. 19C, the converging portion 441c is convex. 19D shows an optical element 420d having two sides 440d formed by connecting portions 441d and 442d. Here, the portion 442d near the bottom surface 422d converges toward the blunt apex 430d and the top portion 441d is perpendicular to the surface of the blunt apex 630d. 19E illustrates an alternative embodiment of optical element 420e with curved side 440e. Here, side 440e is s-shaped, but generally converges towards blunt vertex 430e. When the sides are formed of two or more parts as shown in Figs. 19A-19E, the sides are preferably arranged so that the sides still converge mostly, although this part may have non-converging parts.

Preferably, the size of the underside matches the size of the LED component at the light emitting surface. 20A-20D show exemplary embodiments of such an arrangement. In FIG. 20A, an optical element having a circular bottom 550a is optically coupled to an LED component having a square light emitting surface 570a. Here, the bottom surface and the light emitting surface are matched by making the diameter "d" of the circular bottom surface 550a equal to the diagonal dimension (also "d") of the square light emitting surface 570a. In FIG. 20B, the optical element with hexagonal bottom 550b is optically coupled to the LED component with square light emitting surface 570b. Here, the height "h" of the hexagonal bottom surface 550b coincides with the height "h" of the square light emitting surface 570b. In FIG. 20C, an optical element having a rectangular bottom 550c is optically coupled to an LED component having a square emitting surface 570c. Here, the width "w" of both the bottom surface and the light emitting surface coincide. In FIG. 20D, an optical element having a square bottom 550d is optically coupled to an LED component having a hexagonal light emitting surface 570d. Here, the height "h" of both the bottom surface and the light emitting surface coincide. Of course, a simple arrangement in which both the underside and the emitting surface are identically shaped and have the same surface area also meets this criterion. Here, the surface area of the bottom surface coincides with the surface area of the light emitting surface of the LED component.

Similarly, when the optical element is coupled to the array of LED components, the size of the array at the light emitting side may preferably match the size of the underside of the optical element. In addition, the shape of the array need not match the shape of the base as long as it matches in at least one dimension (eg, diameter, width, height or surface area).

Alternatively, the size of the LED components on the light emitting surface or the combined size of the LED component arrays may be smaller or larger than the size of the underside. 19A and 19C illustrate embodiments in which the light emitting surfaces 412a and 412c of the LED components 410a and 410c respectively match the size of the bottom surfaces 422a and 422c, respectively. 19B shows LED component 410b having a light emitting surface 412b that is larger than bottom 422b. 19D shows an array 412d of LED components in which the combined size at the light emitting surface 412d is greater than the size of the bottom surface 422d. 19E shows LED component 410e having a light emitting surface 412e smaller than the bottom 422e.

For example, where the LED component emitting surface is a square having a side of 1 mm, the optical element underside can be formed to have a matching square having a side of 1 mm. Alternatively, the square emitting surface may be optically coupled to the bottom of the rectangle, wherein one of the sides of the rectangle coincides with the size of the side of the emitting surface. The mismatched sides of the rectangle can be larger or smaller than the sides of the square. Alternatively, the optical element may be manufactured to have a circular base with a diameter equal to the diagonal dimension of the light emitting surface. For example, for a 1 mm x 1 mm square light emitting surface, a circular base with a diameter of 1.41 mm will be considered to be consistent in size for the purposes of the present application. The size of the base can also be made slightly smaller than the size of the light emitting surface. This is one of the aims of minimizing the apparent size of the light source, as described in co-owned US Patent Application Publication No. 2006/0091411 (Oderkirk et al.), Entitled "High Brightness LED Package," entitled Invention. If you can have an advantage.

FIG. 21 illustrates another embodiment of a light source including a converging optical element 624 optically coupled to a plurality of LED components 614a-614c arranged in an array 612. This arrangement is particularly useful when the red, green and blue LEDs are combined within the array to produce white light when the light is mixed. In FIG. 21, the optical element 624 has a converging side 646 that redirects light laterally. Optical element 624 has a bottom 624 shaped as a square optically coupled to an array of LED components 612. The array of LED components 612 also forms a square shape (with side 616).

The optical elements disclosed herein are disclosed in U.S. Patent Application Publication No. 2006/0094340 (Oderkirk et al.), Entitled "Process for Manufacturing Optical Element and Semiconductor Device," by conventional means or assigned to the applicant. US Patent Application Publication No. 2006/0094322 (Oderkirk et al.), Entitled "Process for Producing Light Emitting Array," and November 2005, entitled "Array of Optical Elements and Methods for Making the Same". It may be prepared using the precision polishing technique disclosed in US Patent Application No. 11/288071 (Agent Control Number: 60914US002), filed on May 22.

The disclosed optical elements (particularly including extractors) are transparent and preferably have a relatively high refractive index. Suitable materials for the optical element are high refractive index glass (e.g., Scott glass type LASF35 available from Scott North America, Inc., Elmford, NY, trade name LASF35) and ceramic (e.g. Inorganic materials such as, for example, sapphire, zinc oxide, zirconia, diamond, and silicon carbide). Sapphire, zinc oxide, diamond and silicon carbide are particularly useful because these materials also have relatively high thermal conductivity (0.2-5.0 W / cm K). High refractive index polymers or nanoparticle filled polymers are also contemplated. Suitable polymers can be both thermoplastic polymers and thermoset polymers. Thermoplastic polymers can include polycarbonates and cyclic olefin copolymers. Thermosetting polymers can be, for example, acrylic materials, epoxies, silicones and others known in the art. Suitable ceramic nanoparticles include zirconia, titania, zinc oxide and zinc sulfide.

The refractive index n _o of the optical element is preferably similar to the refractive index n _e of the LED component emitting surface. Preferably, the difference between the two is 0.2 or less (| n _o -n _e | <0.2). Optionally, the difference can be greater than 0.2 depending on the material used. For example, the light emitting surface can have a refractive index of 1.75. Suitable optical elements may have a refractive index (n _o ≧ 1.75) of at least 1.75, including for example n _o ≧ 1.9, n _o ≧ 2.1 and n _o ≧ 2.3. Optionally, n _o may be less than n _e (eg n _o ≧ 1.7). Preferably, the refractive index of the optical element is matched with the refractive index of the main light emitting surface. In some embodiments, the refractive indices of both the optical element and the emitting surface can be the same value (n _o = n _e ). For example, the sapphire emitting element with n _e = 1.76 is a sapphire optical element, or a glass optical element of SF4 (available from Scott North America Inc., Elmford, NY, trade name SF4) with n _o = 1.76. Can be matched with. In another embodiment, the refractive index of the optical element may be higher or lower than the refractive index of the light emitting surface. When made from a high refractive index material, the optical element increases light extraction from the LED components due to the high refractive index and changes the light emission distribution of the light due to its shape, thereby providing a customized light emission pattern.

Throughout this specification, LED component 12 is generally shown for simplicity, but may include conventional design features as known in the art in addition to the re-emitting configuration described above. For example, the LED components can include separate p- and n-doped semiconductor layers, buffer layers, substrate layers, and superstrate layers. While a simple rectangular LED component arrangement is shown, the inclined sides forming other known configurations, for example truncated inverted pyramid LED component shapes, are also contemplated. Electrical contacts to the LED components are also not shown for simplicity, but may be provided on any surface of the die as is known. In an exemplary embodiment, the LED component has two contacts all disposed on the bottom surface in a "flip chip" design. The present invention is not intended to limit the shape of the optical elements or the shape of the LED components, but merely provides illustrative examples.

When the minimum gap between the optical element and the emitting surface of the LED component is below the evanescent wave, the optical element is considered to be optically coupled or in optical contact with the LED component. Optical coupling can be achieved by placing the LED component and the optical element physically close to each other. 14 shows a gap 150 between the light emitting surface 12a of the LED component 12 and the bottom 120 of the optical element 99. Typically, the gap 150 is an air gap and is typically very small to promote a frustrated total internal reflection. For example, in FIG. 14, if the gap 150 is nearly similar to the wavelength of light in the air, the bottom 120 of the optical element 99 is optically close to the light emitting surface 12a of the LED component 12. do. Preferably, the thickness of the gap 150 is smaller than the wavelength of light in the air. In LEDs where multiple wavelengths of light are used, the gap 150 is preferably at most the value of the longest wavelength. Suitable gap sizes include 25 nm, 50 nm and 100 nm. Preferably, the gap is minimized, such as when the input openings or bottoms of the LED components and optical elements are polished to optical flatness and wafer bonded together.

In addition, the gap 150 is substantially uniform over the contact area between the light emitting surface 12a and the bottom 120 and the light emitting surface 12a and the bottom 120 have a roughness of less than 20 nm, preferably less than 5 nm. It is preferable. In such a configuration, light rays emitted from the LED component 12 at an angle that is generally totally internally reflected at the LED component-air interface or outside the escape cone will instead be transmitted into the optical element 20. The surface of the bottom 120 may be shaped to mate with the light emitting surface 12a to facilitate optical coupling. For example, if the emitting surface 12a of the LED component 12 is flat as shown in FIG. 14, the underside 120 of the optical element 99 may also be flat. Alternatively, if the emitting surface of the LED component is curved (eg slightly concave), the underside of the optical element may be shaped to match the emitting surface (eg slightly convex). The size of the bottom 120 may be smaller than, equal to, or larger than the LED component emitting surface 12a. Base 120 may be the same or different cross-sectional shape than LED component 12. For example, an LED component may have a square emitting surface while an optical element has a circular base. Other variations will be apparent to those skilled in the art.

Suitable gap sizes include 100 nm, 50 nm and 25 nm. Preferably, the gap is minimized, such as when the input openings or bottoms of the LED components and optical elements are polished to optical flatness and wafer bonded together. Optical elements and LED components can be bonded together by applying high temperature and high pressure to provide an optically coupled arrangement. Any known wafer bonding technique can be used. Exemplary wafer bonding techniques are described in US Patent Application Publication No. 2006/0094340 (Oderkirk et al.) Entitled "Process for Manufacturing Optical Elements and Semiconductor Devices."

In the case of a limited gap, optical coupling can be achieved or augmented by adding a thin optical conductive layer between the light emitting surface of the LED component and the underside of the optical element. FIG. 22 shows a schematic partial side view of an LED component and an optical element, such as shown in FIG. 14, but with a thin optical conductive layer 660 disposed within the gap 150. Like the gap 150, the optical conductive layer 660 may have a thickness of 100 nm, 50 nm, or 25 nm or less. Preferably, the refractive index of the optical coupling layer matches exactly with the refractive index of the light emitting surface or the optical element. The optical conductive layer can be used in both bonded and non-bonded (mechanical separation) configurations. In bonding embodiments, the optically conductive layer can be any suitable bonding agent that transmits light, including, for example, a transparent adhesive layer, an inorganic thin film, a meltable glass frit, or other similar binder. Further examples of junction configurations are described, for example, in US Patent Application Publication No. 2002/0030194 (Camras et al.) Entitled "Light Emitting Diodes with Improved Light Extraction Efficiency" published March 14, 2002. .

In non-bonded embodiments, the LED component may be optically coupled to the optical element without using any adhesive or other bonding agent between the LED component and the optical element. Non-bonded embodiments allow both the LED component and the optical element to be mechanically separated and to move independently of each other. For example, the optical element can move laterally relative to the LED component. In another example, both the optical and LED components expand freely as each component is heated during operation. In such mechanically isolated systems, most of the shear or normal stress forces generated by expansion are not transferred from one component to another. In other words, the movement of one component does not mechanically affect other components. This configuration may be particularly desirable if the luminescent material is susceptible to breakage, there is a mismatch in thermal expansion coefficient between the LED component and the optical element, and the LED is repeatedly turned on and off.

Mechanically separate configurations can be formed by optically placing the optical element close to the LED component (with only a very small air gap between the two). The air gap should be small enough to promote total internal damping as described above.

Alternatively, as shown in FIG. 22, if a thin optical conductive layer can cause the optical element and the LED component to move independently, this thin optical conductive layer 660 (eg, refractive index matching fluid) It may be added to the gap 150 between the element 99 and the LED component 12. Examples of suitable materials for the optically conductive layer 660 include refractive index matching oils and other liquids or gels having similar optical properties. Optionally, the optically conductive layer 660 can also be thermally conductive.

The optical element and the LED component may be encapsulated together using any known encapsulant material to make a final LED package or light source. Encapsulating the optical element and the LED component provides a way to keep them together in a non-bonded embodiment.

Additional non-junction configurations are described in US Patent Application Publication No. 2006/0091784 (Corner et al.), Entitled “LED Packages with Non-junction Optical Elements,” and which are co-owned by the applicant.

The optical element may be manufactured from one structure, for example cut from one block of material, or may be manufactured in a composite configuration by joining two or more sections together.

The first section is preferably in optical contact with the LED component, and has a high refractive index (preferably approximately equal to the LED component refractive index in terms of emission), and optionally high thermal conductivity, and / or high thermal stability. It is made of one optical material. In this regard, high thermal stability refers to materials having a decomposition temperature of about 600 ° C. or higher. The thickness of the first section is preferably optically thick (eg, at least 5 micrometers effectively, or 10 times the light wavelength).

Silicon carbide is also electrically conductive, thereby providing electrical contact or circuit functionality as well. Scattering in the optical element may be allowed if the scattering is limited to a position adjacent the input end or bottom of the optical element. However, fabricating an optical element with a length sufficient to efficiently combine light from the LED component can be expensive and time consuming. A further challenge in manufacturing one part of the optical element is that the material yield can be relatively low and the form factor allows the LED component to be assembled separately from the optical element. For this reason, it may be advantageous to divide the optical element into two (or more) sections made of different optical materials to reduce the manufacturing cost.

The second section is coupled to the first section and is made of a second optical material, which can be made easier than the first material with a low material cost. The second optical material may have a lower refractive index, lower thermal conductivity, or both as compared to the first optical material. For example, the second optical material may include glass, polymers, ceramics, ceramic nanoparticle filled polymers, and other optically transparent materials. Suitable glasses include those comprising oxides of lead, zirconium, titanium and barium. The glass can be made from compounds comprising titanate, zirconate and tartarate. Suitable ceramic nanoparticles include zirconia, titania, zinc oxide and zinc sulfide.

Optionally, a third section comprised of a third optical material may be coupled to the second section to further assist in coupling the LED light to the external environment. In one embodiment, the refractive indices of the three sections are arranged such that n ₁ > n ₂ > n ₃ to minimize the overall Fresnel surface reflection associated with the optical element.

The disclosed light sources are graphic display devices such as large or small screen video monitors, computer monitors or displays, televisions, telephones or telephone displays, personal digital assistants or personal digital assistant displays, pager or pager displays, calculators or calculator displays, Game console or game console display, toy or toy display, large or small appliance or large or small appliance display, car dashboard or car dashboard display, car interior or car interior display, ship dashboard or ship dashboard display, ship interior or ship Interior display, aircraft dashboard or aircraft dashboard display, aircraft interior or aircraft interior display, traffic controller or bridge The controller may be a display, advertisement display, or a component or an essential component of advertising signs and the like.

The disclosed light source may be such as a component or essential component of a liquid crystal display (LCD) or similar display, ie a backlight for such a display. In some embodiments, the semiconductor device is configured for use as a backlight for liquid crystal displays, in particular by matching the color emitted by the semiconductor device to the color filter of the LCD display.

The disclosed light sources are lighting devices, for example self-contained or built-in lighting fixtures or lamps, landscape or architectural lighting fixtures, handheld or vehicle mounted lamps, automotive headlights or taillights, automotive interior lighting fixtures, signals for automotive or non-automotive use Components or essential components such as road lighting devices, traffic control signals, ship lamps or signals or interior lighting fixtures, aircraft lamps or signals or interior lighting fixtures, large or small appliances or large or small appliance lamps; Or any device or component used as an infrared, visible or ultraviolet light source.

In some cases, the light source comprises (a) a LED capable of emitting light of a first wavelength, (b) a re-emitting semiconductor construction comprising a potential well not located within a pn junction and having a light emitting surface, (c) of the light emitting surface A patterned low refractive index layer in optical contact with the first portion and having a first refractive index, and (d) an optical element having an input surface in optical contact with the second portion of the light emitting surface and having a second refractive index higher than the first refractive index. do. In some cases, the patterned low refractive index layer provides total internal reflection at the light emitting surface for at least some of the light generated within the light source.

In some cases, the light source comprises (a) a re-emitting semiconductor construction comprising (i) an LED capable of emitting light of a first wavelength, and (ii) a potential well not located within the pn junction and having an emitting surface. LED component; (b) means for totally internal reflection of at least a portion of the light generated by the LED component back into the LED component and in optical contact with the first portion of the emitting surface; And (c) an optical element having an input surface in optical contact with a second portion of the emitting surface different from the first portion.

In some cases, the light source has (a) an LED capable of emitting light of a first wavelength, and (ii) an LED having a re-emitting semiconductor construction having a light emitting surface comprising a potential well not located within the pn junction. Component; And (b) a collimating optical element having an input surface and an output surface. In some cases, the input surface is in optical contact with at least a portion of the light emitting surface. In some cases, the optical element comprises a first portion comprising an input surface and composed of a first material. In some cases, the optical element includes a second portion comprising an output end and composed of a second material. In some cases, the first material has a refractive index that is greater than the refractive index of the second material. In some cases, the first portion has a thermal conductivity greater than that of the second material.

In some cases, the light source may comprise (a) a light emitting semiconductor configuration comprising (i) an LED capable of emitting light of a first wavelength, and (ii) a second potential well not located within the pn junction and having an emitting surface. An LED component; And (b) a plurality of optical elements each having an input surface. In some cases, the optical element is sized such that the input surfaces are spaced from each other and in optical contact with different portions of the light emitting surface.

In some cases, the light source includes (a) an LED component having a first potential well located in the pn junction and a second potential well not located in the pn junction, the LED component having a light emitting surface; (b) a patterned low refractive index layer in optical contact with the first portion of the emitting surface and having a first refractive index; And (c) an optical element having an input surface in optical contact with the second portion of the light emitting surface. In some cases, the optical element has a second refractive index that is greater than the first refractive index. In some cases, the patterned low refractive index layer provides total internal reflection at the light emitting surface for at least some of the light generated within the light source.

In some cases, the light source includes (a) an LED component comprising a first potential well located in the pn junction and a second potential well not located in the pn junction and having a light emitting surface; (b) means for totally internal reflection of at least a portion of the light generated by the LED component back into the LED component and in optical contact with the first portion of the emitting surface; And (c) an optical element having an input surface in optical contact with a second portion of the emitting surface different from the first portion.

In some cases, the light source includes (a) an LED component comprising a first potential well located in the pn junction and a second potential well not located in the pn junction and having a light emitting surface; And (b) a collimating optical element having an input surface and an output surface. In some cases, the input surface is in optical contact with at least a portion of the light emitting surface. In some cases, the optical element comprises a first portion comprising an input surface and composed of a first material. In some cases, the optical element includes a second portion comprising an output surface and composed of a second material. In some cases, the first material has a refractive index that is greater than the refractive index of the second material. In some cases, the first material has a thermal conductivity greater than that of the second material.

In some cases, the light source includes (a) an LED component comprising a first potential well located in the pn junction and a second potential well not located in the pn junction and having a light emitting surface; And (b) a plurality of optical elements each having an input surface. In some cases, the optical element is sized such that the input surfaces are spaced from each other and in optical contact with different portions of the light emitting surface.

In some cases, the light source may comprise (a) an LED capable of emitting light of a first wavelength and having a light emitting surface; (b) a re-emitting semiconductor construction comprising a potential well not located within a pn junction; (c) a patterned low refractive index layer in optical contact with the first portion of the emitting surface and having a first refractive index; And (d) an optical element having an input surface in optical contact with the second portion of the light emitting surface. In some cases, the optical element has a second refractive index that is greater than the first refractive index. In some cases, the patterned low refractive index layer provides total internal reflection at the light emitting surface for at least some of the light generated within the light source.

In some cases, the light source comprises (a) a re-emitting semiconductor construction comprising (i) an LED capable of emitting light of a first wavelength and having an emitting surface, and (ii) a potential well not located within the pn junction. LED component; (b) means for totally internal reflection of at least a portion of the light generated by the LED component back into the LED component and in optical contact with the first portion of the emitting surface; And (c) an optical element having an input surface in optical contact with a second portion of the emitting surface different from the first portion.

In some cases, the light source comprises (a) a re-emitting semiconductor construction comprising (i) an LED having a light emitting surface and having a light emitting surface, and (ii) a potential well not located within the pn junction. LED component; And (b) a collimating optical element having an input surface and an output surface. In some cases, the input surface is in optical contact with at least a portion of the light emitting surface. In some cases, the optical element comprises a first portion comprising an input surface and composed of a first material. In some cases, the optical element includes a second portion comprising an output surface and composed of a second material. In some cases, the first material has a refractive index that is greater than the refractive index of the second material. In some cases, the first material has a thermal conductivity greater than that of the second material.

In some cases, the light source comprises (a) a re-emitting semiconductor construction comprising (i) an LED having a light emitting surface and having a light emitting surface, and (ii) a potential well not located within the pn junction. LED component; And (b) a plurality of optical elements each having an input surface. In some cases, the optical element is sized such that the input surfaces are spaced from each other and in optical contact with different portions of the light emitting surface.

In some cases, the light source comprises (a) a LED capable of emitting light of a first wavelength, (b) a re-emitting semiconductor construction having a potential well that is not located within a pn junction and having a light emitting surface; And (c) a light extractor having an input surface in optical contact with the light emitting surface.

In some cases, the light source includes (a) an LED component comprising a first potential well located in the pn junction and a second potential well not located in the pn junction and having a light emitting surface; And (b) a light extractor having an input surface in optical contact with the light emitting surface.

In some cases, the light source may comprise (a) an LED capable of emitting light of a first wavelength and having a light emitting surface; (b) a re-emitting semiconductor construction comprising a potential well not located within a pn junction; And (c) a light extractor having an input surface in optical contact with the light emitting surface.

In some cases, the light source includes (a) an LED capable of emitting light of a first wavelength; (b) a re-emitting semiconductor construction comprising a potential well not located within a pn junction and having a light emitting surface; And (c) a patterned low refractive index layer in optical contact with the first portion of the light emitting surface that is less than all of the light emitting surface. In some cases, the patterned layer has a refractive index lower than the refractive index of the emitting surface.

In some cases, the light source includes (a) an LED component comprising a first potential well located in the pn junction and a second potential well not located in the pn junction and having a light emitting surface; And (b) a patterned low refractive index layer in optical contact with the first portion of the light emitting surface that is less than all of the light emitting surface. In some cases, the patterned layer has a refractive index lower than the refractive index of the emitting surface.

In some cases, the light source may comprise (a) an LED capable of emitting light of a first wavelength and having a light emitting surface; (b) a re-emitting semiconductor construction comprising a potential well not located within a pn junction; And (c) a patterned low refractive index layer in optical contact with the first portion of the light emitting surface that is less than all of the light emitting surface. In some cases, the patterned layer has a refractive index lower than the refractive index of the emitting surface. In some cases, the graphic display device or lighting device includes such a light source.

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and principles of this invention, and it should be understood that this invention is not unduly limited to the illustrative embodiments set forth above.

Claims (21)

An LED component having a light emitting surface and comprising a LED capable of emitting light of a first wavelength and a re-emitting semiconductor construction comprising a second potential well not located within a pn junction; And A light source comprising an optical element having an input surface and an output surface in optical contact with at least a portion of the light emitting surface. The light source of claim 1, wherein the second potential well is a quantum well or comprises a quantum well. The light source of claim 1, wherein the LED comprises a first potential well located within a pn junction. The light source of claim 1, wherein the light emitting surface is a surface of the LED die and the optical element is disposed between the LED die and the re-emitting semiconductor construction. The light source of claim 4, wherein the re-emitting semiconductor construction is bonded to the output surface of the optical element. The light source of claim 1, wherein the light emitting surface is a surface of a re-emitting semiconductor construction, wherein the re-emitting semiconductor construction is disposed between the LED and the optical element. The light source of claim 6, wherein the re-emitting semiconductor construction is attached to the LED by a bonding layer. The light source of claim 6, wherein the re-emitting semiconductor construction and the LED have a single configuration formed on the same semiconductor wafer. The light source of claim 1, wherein the optical element comprises an encapsulant. The light source of claim 1, wherein the optical element comprises an extractor. The light source of claim 1, wherein the optical element comprises a lens. The light emitting device of claim 1, further comprising a patterned low refractive index layer in optical contact with the first portion of the emitting surface and having a first refractive index, wherein the input surface of the optical element is in optical contact with the second portion of the emitting surface, The element has a second refractive index higher than the first refractive index. The optical component of claim 1, further comprising means for totally internally reflecting at least a portion of the light generated by the LED component back into the LED component and in optical contact with the first portion of the light emitting surface, wherein the input surface of the optical element is formed of the first component. A light source in optical contact with a second portion of the emitting surface different from one portion. The optical element of claim 1, wherein the optical element comprises a first portion comprising an input surface and comprised of a first material, the optical element comprising a second portion comprising an output end and comprised of a second material, wherein the first material is A light source having a higher refractive index than the second material. The light source of claim 1, wherein the optical element is one of a plurality of optical elements each having an input surface, the optical element having a size such that the input surfaces are spaced from each other and in optical contact with a different portion of the light emitting surface. The light source of claim 1, wherein the optical element comprises a bottom, two converging sides, and two diverging sides. The light source of claim 1, wherein the optical element is shaped to direct light emitted by the LED component to produce a side emission pattern. The light source of claim 1, wherein the optical element comprises a bottom, a vertex smaller than the bottom, and a converging side extending between the bottom and the vertex. 19. The light source of claim 18, wherein the bottom is an input face of the optical element and the bottom is no larger than the light emitting face of the LED component. Graphic display device comprising a light source according to claim 1. Lighting device comprising a light source according to claim 1.

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