KR20090018627A - Led device with re-emitting semiconductor construction and reflector - Google Patents

Abstract

Briefly, the present disclosure provides a device comprising: a) an LED capable of emitting light at a first wavelength; b) a re-emitting semiconductor construction which comprises a potential well not located within a pn junction; and c) a reflector positioned to reflect light emitted from the LED onto the re-emitting semiconductor construction. Alternately, the device comprises: a) an LED capable of emitting light at a first wavelength; b) a re-emitting semiconductor construction capable of emitting light at a second wavelength which comprises at least one potential well not located within a pn junction; and c) a reflector which transmits light at said first wavelength and reflects at least a portion of light at said second wavelength. Alternately, the device comprises a semiconductor unit comprising a first potential well located within a pn junction which comprises a LED capable of emitting light at a first wavelength, and a second potential well not located within a pn junction which comprises a re-emitting semiconductor construction.

Description

LED DEVICE WITH RE-EMITTING SEMICONDUCTOR CONSTRUCTION AND REFLECTOR}

Cross Reference with Related Application

This application claims the benefit of U.S. Provisional Patent Application 60/804538, filed June 12, 2006, the disclosure of which 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 in which light emitted from a light emitting diode (LED) impinges on a re-emitting semiconductor configuration and excites such semiconductor configuration to down-convert a portion of the emitted light to a longer wavelength. It is about.

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. US Pat. No. 5,998,925 and US Pat. No. 6,734,467 may be related to such techniques.

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.

In summary, the present invention provides a light emitting diode comprising: 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 c) a reflector positioned to reflect light emitted from the LED onto the re-emitting semiconductor construction. The re-emitting semiconductor construction can additionally include an absorbing layer adjacent or immediately adjacent to the potential well. The potential well may be a quantum well. In one embodiment, the re-emitting semiconductor construction can emit light of a second wavelength, and the reflector reflects light of the first wavelength and transmits light of the second wavelength. The reflector can be a multilayer reflector, a non-planar flexible multilayer reflector, or a reflective polarizer layer.

In another aspect, the present invention provides a light emitting diode comprising: a) an LED capable of emitting light of a first wavelength; b) a re-emitting semiconductor construction comprising one or more potential wells capable of emitting light of a second wavelength and not located within a pn junction; And c) a reflector that transmits light of the first wavelength and reflects at least a portion of the light of the second wavelength. The re-emitting semiconductor construction can additionally include an absorbing layer adjacent or immediately adjacent to the potential well. The potential well may be a quantum well. The reflector may be located between the LED and the re-emitting semiconductor construction. The reflector may be a multilayer reflector or a non-planar flexible multilayer reflector.

In another aspect, the invention constitutes a) i) a first potential well constituting an LED located within a pn junction and capable of emitting light of a first wavelength, and ii) a re-emitting semiconductor construction not located within the pn junction. A semiconductor unit comprising a second potential well; And b) a reflector positioned to reflect light emitted from the LED onto the re-emitting semiconductor construction. The re-emitting semiconductor construction can additionally include an absorbing layer adjacent or immediately adjacent to the potential well. The potential well may be a quantum well. In one embodiment, the re-emitting semiconductor construction can emit light of a second wavelength, and the reflector reflects light of the first wavelength and transmits light of the second wavelength. The reflector can be a multilayer reflector, a non-planar flexible multilayer reflector, or a reflective polarizer layer.

In another aspect, the present invention provides a graphic display device comprising the LED element according to the present invention.

In another aspect, the present invention provides a lighting device comprising the LED element according to the present invention.

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" means a potential well whose quantization effect is thin enough to elevate the electron-hole pair transition energy in the well, typically 100 nm or less in thickness,

"Transition energy" means electron-hole recombination energy,

"Grid-matching" 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 0.2 to each other. Less than%, more typically less than 0.1% of each other, most typically less than 0.01% of each other,

"Georgeous asymmetry" 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, and these lattice constants are sufficiently Similarly, it means 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 of the embodiments of the invention described herein, including n-doped and p-doped semiconductor regions, additional embodiments in which n doping is reversed and vice versa are to be considered as disclosed herein. It should be understood.

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 in accordance with one embodiment of the present invention (layer thickness is not represented 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 a device according to an embodiment of the present invention.

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

5 is a schematic cross-sectional view of a device according to the present invention.

6 is a cross-sectional view of the re-emitting semiconductor construction and reflector assembly used in the device of FIG.

7-9 are schematic cross-sectional views of alternative devices in accordance with the present invention.

10 shows a portion of another device according to the invention.

11 is a schematic cross-sectional view of another device according to the invention.

12 is a schematic side view of another element using front surface illumination, similar to the embodiment of FIG. 10.

13 is a schematic side view of a device using an arrangement of nonimaging concentrators.

14 is an enlarged view of a portion of FIG. 12.

15-19 are schematic side views of another embodiment of the present invention.

The present invention provides a device comprising a LED, a re-emitting semiconductor construction, and a reflector positioned to reflect light emitted from the LED into the re-emitting semiconductor construction. 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 another embodiment, the device includes a reflector that transmits light of the first wavelength and reflects at least a portion of the light of the second wavelength. Such reflectors may be located between the LED and the re-emitting semiconductor construction.

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. In one embodiment, the re-emitting semiconductor construction additionally includes an absorbing layer adjacent or immediately adjacent to the potential well. The absorbing layer typically has a band gap energy that is less than or equal to the energy of photons emitted by the LED and greater than the transition energy of the potential wells of the re-emitting semiconductor construction. In typical operation, the absorber layer aids in the absorption of photons emitted from the LED. In one embodiment, the re-emitting semiconductor construction additionally includes 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 one embodiment, the LED is a UV 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 one embodiment, the LED is a visible light LED, typically a green, blue or purple LED, more preferably a green or blue LED, most preferably a blue LED. 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.

Any suitable LED can be used in the practice of the present invention. Elements of the device according to the invention, including LED and re-emitting semiconductor constructions, include Group IV elements such as Si or Ge (in addition to the light emitting layer), InAs, AlAs, GaAs, InP, AlP, GaP, InSb, AlSb, GaSb and their alloys. Group III-V compounds, such as ZnSe, CdSe, BeSe, MgSe, ZnTe, CdTe, BeTe, MgTe, ZnS, CdS, BeS, MgS and alloys thereof, or alloys of any of the above It may be composed of any suitable semiconductor including. 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 one embodiment of the invention, the composition of the various layers of components of the device, such as LED and / or re-emitting semiconductor construction, is selected in view of the following considerations. Each layer is typically either pseudomorphic 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 will determine the amount of quantization energy in the quantum well, which is added to the bulk band gap energy to determine 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 one embodiment of the present invention, the emission wavelength is selected such that the combined output of the light emitted by the device produces an appearance of any color, which color may be white or almost white, pastel, magenta, cyan, or the like. It can be generated by a combination of two, three or more monochromatic light sources comprising. In another embodiment, the device according to the invention emits light of visible wavelengths as light of invisible infrared or ultraviolet wavelengths and 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 conduction and valence bands of a semiconductor in a re-emitting semiconductor construction in accordance with one embodiment of the present invention. 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 the light emitted from the quantum wells 3 and 7 and the short wavelength LED 20. 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 of the invention shown in FIG. 1 operates in accordance with the following principles: blue wavelength photons emitted by the LED and reflected onto the re-emitting semiconductor construction, It can be re-emitting as a green wavelength photon from the green luminescent quantum well 7 or as a red wavelength photon from the red luminescent 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 according to the invention.

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 of the invention, the LED and re-emitting semiconductor constructions are provided in one semiconductor unit. 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 and the other corresponds to the transition energy of the second potential well. 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 in accordance with one embodiment of the present invention. Layer thickness is not shown 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, and 14 represent pn junctions, or more specifically pin junctions, in which the intermediate undoped (“native” doping) layers 11, 12, 13 are n-doped. Interposed between the layer 10 and the 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 of the present invention operates in accordance with the following principle: When a current passes from layer 14 to layer 10, the blue wavelength photon is protons in the pn junction. Ejected from well 12. 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 according to the invention.

Referring back to the embodiment shown in FIG. 4, the absorbing layers 3, 5, 7 and 9 may be particularly suitable for absorbing photons emitted from the first quantum well 12, in which the absorbing layers are first quantum. This is because it has a band gap energy intermediate between the transition energy of the well 12 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 10 may include red, green and blue light emitting quantum wells.

The device according to the invention may comprise an additional layer of conductor, semiconductor or non-conductor material. Electrical contact layers can be added to provide a path for supply of current to the LEDs. A light filtration layer may be added to change or correct the equilibrium of the light wavelengths of light emitted by the constructed LEDs.

In one embodiment, the device according to the invention produces white or nearly white light by emitting light of four principal wavelengths in the blue, green, yellow and red bands. In one embodiment, the device according to the invention produces white or almost white light by emitting light of two main wavelengths in the blue and yellow bands.

The device according to the invention comprises 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 ( It can include additional semiconductor elements, including thyristors, triacs, voltage regulators, and other circuit elements. The device according to the invention may comprise an integrated circuit. The device according to the invention may comprise a display panel or an illumination panel.

The LED and re-emitting semiconductor constructions constituting the device according to the present invention can be prepared by any suitable method which may include molecular beam epitaxy (MBE), chemical vapor deposition, liquid phase epitaxy and vapor phase epitaxy. Elements of the device according to the invention may comprise a substrate. Any suitable substrate can be used in the practice of the present invention. 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, elements of the device according to the invention may be free of substrates. In one embodiment, elements of the device according to the invention can be formed on a substrate and then separated from the substrate. The elements of the device according to the invention can be joined together by any suitable method, including the use of adhesive or welding materials, pressure, heat or a combination thereof. Typically, the resulting bond is transparent. The bonding method may include interfacial bonding or edge bonding. Optionally, a refractive index matching layer or interstitial space may be included.

Any suitable reflector can be used in the device of the present invention. Typically, a multilayer reflector is used, which may be a non-planar flexible multilayer reflector. Multilayer reflectors include polymeric multilayer optical films, ie, films having alternating layers of at least tens, hundreds, or thousands of first and second polymeric materials, the thickness and refractive index of which are limited by reflection bands or visible wavelengths limited by UV wavelengths. It is chosen to achieve the desired reflectivity in the desired portion of the spectrum, such as the reflection band. See, for example, US Pat. No. 5,882,774 (Jonza et al.). The reflection bands produced by these films also experience a blue-shift associated with an angle of incidence similar to the blue-shift associated with a stack of inorganic isotropic materials, but polymer multilayer optical films are characterized in that adjacent pairs of layers are perpendicular to the film. the reflectivity of each interface between adjacent layers with respect to the p-polarized light is slowly reduced with incident angle, or substantially independent of the incident angle, treated to have a matching or nearly matching or intentionally mismatched refractive index associated with the z-axis, or It may increase with an angle of incidence away from the normal. Thus, such polymeric multilayer optical films can maintain high reflectivity levels for p-polarized light even at very inclined angles of incidence, thereby reducing the amount of p-polarized light transmitted by the reflective film compared to conventional inorganic isotropic stack reflectors. Decrease. In order to achieve these properties, the polymer material and the processing conditions require that for each pair of adjacent optical layers the difference in refractive index along the z-axis (parallel to the thickness of the film) is the difference in refractive index along the x or y (in-plane) axis. Is selected to be equal to or less than 0.5, 0.25 or even 0.1. Alternatively, the refractive index difference along the z axis may be opposite in sign to the in-plane refractive index difference.

In addition, the use of polymeric multilayer optical films enables various new embodiments and construction methods to be exploited by the flexibility and formability of such films, with or without the aforementioned refractive index relationships. For example, the polymeric multilayer optical film may be permanently modified by embossing, thermoforming or other known means to have a three-dimensional shape, such as a portion of a paraboloid, sphere or ellipsoid. In general, see US Patent Application Publication No. 2002/0154406 (Merrill et al.). See also US Pat. No. 5,540,978 (Schrenk) for further polymeric multilayer film examples. Unlike conventional inorganic isotropic stacks, in which layer layers are usually vapor deposited on rigid, brittle substrates, polymeric multilayer optical films can be made in the form of large volumes of rolls, also laminated and coated on other films, and further described below. As described, it may be die cut or otherwise subdivided into small pieces for easy incorporation into the optical system. Suitable polymer multilayer optical film subdivision methods are disclosed in pending US patent application Ser. No. 10 / 268,118, filed Oct. 10, 2002.

A wide range of polymeric materials is suitable for use in multilayer optical films for LED containing devices. However, especially when the device comprises a white light re-emitting semiconductor construction coupled to a UV LED excitation source, the multilayer optical film preferably comprises an alternating polymer layer composed of a material that resists degradation when exposed to UV light. In this respect, particularly preferred polymer pairs are polyethylene terephthalate (PET) / co-polymethylmethacrylate (co-PMMA). The UV stability of the polymer reflector can also be increased by the inclusion of non-UV absorbing light stabilizers such as Hindered Amine Light Stabilizers (HALS). In some cases, the polymeric multilayer optical film may also include a transparent metal or metal oxide layer. See, eg, PCT Publication WO 97/01778 (Ouderkirk et al.). In applications where particularly high intensity UV light is used, which allows even strong polymer material combinations to be unacceptably degraded, it may be advantageous to form a multilayer stack using inorganic materials. The inorganic material layer can be isotropic and can be made to exhibit birefringence as described in PCT Publication WO 01/75490 (Weber), thus advantageously obtaining improved p-polarized reflectivity as described above. Has a refractive index relationship. In most cases, however, it is most convenient and cost effective for the multilayer optical film to be substantially polymer completely without inorganic materials.

5 and 6 combine the re-emitting semiconductor construction 22 in combination with one or both of the long pass (LP) reflector 24 and the short pass (SP) reflector 26 (both shown). One embodiment of forming a reflector-re-light emitter configuration 16 is shown. LP reflectors or filters based on scattering processes can achieve relatively constant performance as a function of angle of incidence. LP and SP mirrors constructed from stacks of inorganic dielectric materials may have good spectral selectivity over a narrow range of angles of incidence. The device 10 further includes an LED 12 on a mount 14 and may include a capsule 18 having a convex surface 20.

If the LED and re-emitting semiconductor constructions constitute one semiconductor unit, only a long pass (LP) reflector 24 may be needed.

7-9 show alternative configurations of elements 40, 50, 60 using concave multilayer optical film LP reflectors 46, 56. FIGS. The separation of the LP reflectors 46, 56 from the re-emitting semiconductor constructions 42, 52 and bending them to provide concave surfaces for the re-emitting semiconductor constructions 42, 52 and the LEDs 12 is an LP reflector 46, 56. It helps to reduce the range of the angle of incidence of the excitation light impinging on), thereby reducing the leakage of LED light through the LP reflectors 46, 56 generated by its blue shifting effect. Preferably, the multilayer optical film is permanently deformed into a concave surface of a suitable shape before being immersed in the transparent medium 18 by embossing or other suitable process. The multilayer optical film is a mirror reflector within each reflection band, whether LP or SP. Diffuse reflections from multilayer optical films are typically negligible.

In FIG. 7, device 40 includes a relatively small area of re-emitting semiconductor construction layer 42 disposed on an optional SP reflector 44 composed of a polymer multilayer optical film. The LP reflector 46 is embossed to obtain a concave shape and positioned close to the other components 42 and 44 of the re-emitting semiconductor construction-reflector assembly. The LED 12 and the heat sink 14 are arranged to direct the excitation light emitted by the LED toward the center of the re-emitting semiconductor construction layer 42. Preferably, the excitation light has the greatest influence at or near the center of the re-emitting semiconductor construction layer 42. The excitation light that is not absorbed at the first crossing of the re-emitting semiconductor component layer 42 passes through the region 48 between the LP reflector 46 and the re-emitting semiconductor component layer 42, and then is caused by the LP reflector 46. Reflected back towards the re-emitting semiconductor construction layer. Region 48 may be comprised of transparent potting material 18 or alternatively another polymeric material, or air (or other gas) or glass. LP reflector 46 is preferably shaped to maximize the amount of excitation light reflected back to the re-emitting semiconductor construction.

FIG. 8 shows device 50 similar to device 40 except that the size of re-emitting semiconductor construction layer 52, SP reflector 54, and LP reflector 56 is increased. For a given distance from the LED 12 to the re-emitting semiconductor component layer and the same heat sink 14 geometry, the larger LP reflector 56 has a higher concentration of light at the center of the re-emitting semiconductor component layer. Will get The smaller central emission area of the re-emitting semiconductor construction layer provides a smaller range of angles of incidence of re-emitting light on the surface of the LP reflector, improving overall device efficiency. As before, region 58 may be comprised of potting material 18 or other polymeric material, or air (or other gas), or glass.

The element 60 shown in FIG. 9 is similar to the element 50 except that the LP reflector 66 now forms the outer surface of the light source. Region 68 may be filled with potting material 18 or other transparent medium.

The re-emitting semiconductor construction layers of FIGS. 7-9 can be patterned to define the re-emitting semiconductor construction in a continuous or most efficient position. In addition, in the embodiments of FIGS. 5 and 7 and 9 and in other embodiments in which the re-emitting semiconductor construction-reflector assembly is disposed above and spaced apart from the LEDs, the device may be manufactured in two halves. That is, one includes an LED with a heat sink and the other includes a re-emitting semiconductor component layer and multilayer reflector (s). These two halves can be made separately and then joined together or otherwise fixed. Such construction techniques can help to simplify manufacturing and increase overall yield.

FIG. 10 illustrates a concept that may be advantageously applied to other embodiments herein, that is, providing an air gap between the LED and the re-emitting semiconductor component layer and / or in the vicinity of one or more elements of the re-emitting semiconductor component-reflector assembly. To provide. Only some elements of the device are shown in this figure for the sake of simplicity. The air gap 70 is shown between the LED 12 and the re-emitting semiconductor construction layer 72, ie, the adjacent multilayer optical film SP reflector 74. The air gap is minimally affected by the excitation light from the LED reaching the re-emitting semiconductor component layer because of the relatively small angle involved. However, the air gap enables total internal reflection (TIR) of light traveling at large angles of incidence, such as light traveling within the SP reflector 74, re-emitting semiconductor construction layer 72, and LP reflector. In the embodiment of FIG. 10, the efficiency of the SP reflector 74 is improved by enabling TIR at the bottom surface of the reflector 74. Alternatively, the SP reflector 74 can be removed and an air gap can be formed directly under the re-emitting semiconductor construction layer 72. An air gap may also be formed adjacent to the LP reflector at the top side or at its top or bottom side of the re-emitting semiconductor construction layer 72. One approach to providing an air gap involves the use of known microstructured films. Such films have a substantially flat surface opposite the microstructured surface. The microstructured surface may be characterized by a set of linear v-shaped grooves or prisms, multiple cross sets of v-shaped grooves forming an array of small pyramids, one or more sets of narrow ridges, and the like. When the microstructured surface of such a film is disposed against another flat film, an air gap is formed between the top portions of the microstructured surface.

As the re-emitting semiconductor construction converts light of one wavelength (excitation wavelength) to another wavelength (emission wavelength), heat may be generated. The presence of an air gap near the re-emitting semiconductor construction can significantly reduce heat transfer from the re-emitting semiconductor construction to the surrounding material. Reduced heat transfer can be compensated in other ways, for example by providing a layer of glass or transparent ceramic near the layer of re-emitting semiconductor that can laterally remove heat.

Another approach to improving the efficiency of the device according to the invention is that at least a portion of the excitation light from the LED is directed to the top (observation) of the re-emitting semiconductor construction layer rather than directed all the excitation light on the bottom surface of the re-emitting semiconductor construction layer. It is to configure the LED, the re-emitting semiconductor construction layer and the LP reflector to be reflected by the LP reflector directly on the face. 11 shows such a device 80. The heat sink 14 ′ has been modified from the above embodiment so that the LED 12 and the re-emitting semiconductor construction layer 82 may generally be mounted in the same plane. The SP reflector 84 is shown underneath the re-emitting semiconductor construction layer, but in many cases will not be required. This causes the LP reflector 86 embossed in the form of a concave ellipsoid or similar shape to direct UV excitation light directly from the LED onto the top surface of the re-emitting semiconductor construction layer 82, which surface faces the front of the device 80. For heading. The LED and re-emitting semiconductor construction layers are preferably arranged at the focal point of the ellipsoid. Visible light emitted by the re-emitting semiconductor construction layer is transmitted by the LP reflector 86 and received by the rounded front end of the device body to form the desired pattern or visible (preferably white) light.

Directing excitation light directly to the front face of the re-emitting semiconductor construction layer has a number of benefits. The brightest portion of the re-emitting semiconductor component layer, where the excitation light is the strongest, is now exposed in front of the device rather than obscured through the thickness of the re-emitting semiconductor component layer. The re-emitting semiconductor construction layer is made substantially thicker to absorb substantially all UV excitation light without worrying about the thickness / brightness tradeoff mentioned above. The re-emitting semiconductor construction can be mounted on a broadband metal mirror comprising silver or reinforced aluminum.

12 schematically illustrates another embodiment where the LED light impinges on the front face of the re-emitting semiconductor construction layer but some of the LED light also impinges on the back face. In this embodiment, some light emitted by the LED 12 impinges on the rear surface of the re-emitting semiconductor construction layer 92, while some LED light is also reflected from the concave LP reflector 96 to reflect the re-emitting semiconductor. The front surface of the re-emitting semiconductor construction layer 92 is hit without traversing through the construction. The visible light emitted by the re-emitting semiconductor construction layer 92 then passes through the LP reflector 96 towards the observer or illuminator. The LED, re-emitting semiconductor component layer and LP reflector can all be immersed or attached to a transparent potting medium as shown in the previous embodiment.

FIG. 13 schematically illustrates another embodiment where a combination of non-imaging collectors is arranged to enhance the operation of a multilayer optical film. Specifically, light collector elements 100a, 100b, 100c are provided as shown between LED 12, SP reflector 104, re-emitting semiconductor construction layer 102 and LP reflector 106. The collector element has the effect of reducing the angular spread of light impinging on the multilayer reflector, thus reducing the blue shift of the reflection band described above with respect to FIGS. The collector element may be in the form of a simple conical section with flat sidewalls, or the sidewalls may take on a more complex curved shape as is known to enhance collimation or condensing action along the direction of light movement. In either case, the side walls of the collector element are reflective and the two ends (one small and one large) are not reflective. In FIG. 13, the LED 12 is disposed at the small end of the light collector 100a. The light collector element 100a collects a wide range of light emitted by the LED, which range is reduced when such light is moved to the large end of the light collector element 100a on which the SP reflector 104 is mounted. The SP reflector transmits UV excitation light to the light collector element 100b, which collects such light on the re-emitting semiconductor construction layer 102 (increasing the angular dispersion of light). The wide angular range of visible light emitted downward by the re-emitting semiconductor component layer 102 is converted by the condenser element 100b into a narrower angular range in the SP reflector 104, where the light is converted into the narrow-emitting semiconductor component layer ( Is reflected back up again. On the other hand, the excitation light leaked through the re-emitting semiconductor component layer 102 and the visible light emitted upward by the re-emitting semiconductor component layer 102 initially have a wide angular dispersion, but are smaller by the light collector element 100c. Converted to angular dispersion, the LP reflector 106 will better transmit visible light emitted by the re-emitting semiconductor construction and reflect back the excitation light towards the re-emitting semiconductor construction layer.

To capture as much LED excitation light as possible, the small end of the collector element 100a may have a cavity to capture at least some of the light emitted by the face of the LED, as shown in FIG. 14. .

Further discussion

The interference reflector described herein includes a reflector formed of organic, inorganic, or a combination of organic and inorganic materials. The interference reflector may be a multilayer interference reflector. The interference reflector can be a flexible interference reflector. Flexible interference reflectors can be formed from polymers, non-polymeric materials, or polymeric and non-polymeric materials. Exemplary films comprising polymeric and nonpolymeric materials are disclosed in US Pat. Nos. 6,010,751 and 6,172,810, and European Patent Publication No. 733,919 A2, both of which are incorporated herein by reference.

The interference reflector described herein can be formed from a flexible, plastic, or deformable material, and can itself be flexible, plastic, or deformable. These interference reflectors can be curved or bent to the radius available for conventional LEDs, ie 0.5 to 5 mm. These flexible interference reflectors can be bent or curved and still maintain pre-deflection optical properties.

Known self-assembled periodic structures such as cholesteric reflective polarizers and certain block copolymers are considered to be multilayer interference reflectors for this application. Cholesteric mirrors can be made using a combination of left and right chiral pitch elements.

In an exemplary embodiment, a long pass filter that partially transmits blue light of all wavelengths is used in combination with a thin yellow re-emitting semiconductor component layer to first pass through the re-emitting semiconductor component and then back from the LED onto the re-emitting semiconductor component layer. May direct some blue light.

In addition to providing reflection of UV light, the function of the multilayer optical film can block the transmission of UV light to prevent deterioration of subsequent elements inside or outside the LED package, including preventing damage to the human eye. In some embodiments, it may be advantageous to include a UV absorber on the side of the UV reflector furthest from the LED. Such UV absorbers can be in, on or adjacent to the multilayer optical film.

While a variety of methods are known in the art for producing interference filters, any polymer configuration can provide a number of manufacturing and cost benefits. When high temperature polymers with high optical transmittances and large refractive index differences are used in the interference filter field, thin, highly flexible, environmentally stable filters may be manufactured to meet the optical needs of short pass (SP) and long pass (LP) filters. Can be. In particular, a coextruded multilayer interference filter as disclosed in US Pat. No. 6,531,230 (Weber et al.) Can provide not only accurate wavelength selection but also large area, cost effective manufacturing. The use of polymer pairs with high refractive index differences makes it possible to construct very thin high reflection mirrors that are self-supporting, ie have no substrate but are very easily processed. Such interference structures will not crack, crush or otherwise degrade when thermoformed or when bent to a radius of curvature as small as 1 mm.

The filters, which are all polymers, can be thermoformed into various 3D shapes, such as, for example, hemispherical domes (as described below). However, care must be taken to control thinning in the correct amount across the entire surface of the dome to produce the desired angular performance. Filters with simple two-dimensional curvature are easier to produce than filters of 3D composite shape. In particular, any thin flexible filter can be bent into a 2D shape, for example as part of a cylinder, in which case it is not necessary to have a filter that is entirely polymer. The multilayer inorganic filter on the thin polymer substrate can be molded in this manner as well as the inorganic multilayer on the glass substrate having a thickness of less than 200 micrometers. The inorganic multilayer may need to be heated to a temperature close to the glass transition temperature to obtain a permanent shape with low stress.

The optimal bandedge for long pass filters and short pass filters will depend on the emission spectrum of both the LED and re-emitting semiconductor configurations in the system in which the filter is designed to operate. In an exemplary embodiment, in the case of a short pass filter, substantially all of the LED emission passes through the filter to excite the re-emitting semiconductor configuration, and substantially all of the emission of the re-emitting semiconductor configuration is reflected by the filter so that they are absorbed by the LEDs or they are absorbed. Do not enter the base structure where possible. For this reason, the short pass pass band edge is disposed in the region between the average emission wavelength of the LED and the average emission wavelength of the re-emitting semiconductor construction. In an exemplary embodiment, the filter is disposed between the LED and the re-emitting semiconductor construction. However, if the filter is planar, light emission from a typical LED may strike the filter at various angles, and at some angles of incidence, will not be reflected by the filter and reach the re-emitting semiconductor construction. If the filter is not curved to maintain a nearly constant angle of incidence, it may be desirable to place the design band edge at wavelengths greater than the midpoint of the re-emitting semiconductor construction and the LED emission curve to optimize overall system performance. In particular, very small light emission of the re-emitting semiconductor construction is directed towards the filter at an angle of incidence of almost zero degrees because the included solid angle is very small.

In another exemplary embodiment, the long pass reflecting filter is disposed opposite the re-emitting semiconductor construction layer from the LED, regenerating the LED excitation light back to the re-emitting semiconductor construction to improve system efficiency. In an exemplary embodiment, the long pass filter may be omitted if the LED emission is in the visible light spectrum and a large amount of LED emission is required to balance the re-emitting semiconductor construction color output. However, a blue LED / yellow re-emitting semiconductor is provided through a spectral angle shift that uses a long pass filter that partially transmits short wavelength light, for example blue light, to pass more blue light at large angles upon vertical incidence. Optimize the angular performance of your configuration system.

In a further exemplary embodiment, the LP filter is curved to maintain a nearly constant angle of incidence of the LED emitted light on the filter. In this embodiment, both the re-emitting semiconductor construction and the LEDs are directed to one side of the LP filter. At large angles of incidence, the LP filter will not reflect short wavelength light. For this reason, the long wavelength band edge of the LP filter can be disposed at the longest wavelength possible while blocking the light emission of the re-emitting semiconductor construction as little as possible. In addition, the band edge placement can be changed to optimize the overall system efficiency.

The term "adjacent" is defined herein to indicate the relative position of two articles close to each other. Adjacent items may be contacted or spaced apart from one another with one or more materials disposed between adjacent items.

The LED excitation light may be any light that the LED light source can emit. The LED excitation light can be UV or blue light. Blue light also includes purple and indigo light. LEDs include not only co-emitting devices, but also devices using inductive or super-radiative light emission, including laser diodes and vertical resonant surface emitting laser diodes.

The layers of the re-emitting semiconductor construction described herein may be continuous or discontinuous layers. The layer of re-emitting semiconductor construction material may be a uniform or non-uniform pattern. The layer of re-emitting semiconductor construction material may be a plurality of regions having a small area. In an exemplary embodiment, each of the plurality of regions is one or more different from each other, for example, a red emitting region, a blue emitting region and a green emitting region. It can be formed from a re-emitting semiconductor construction that emits visible light of a wavelength. The regions emitting a plurality of wavelengths of visible light can be arranged and configured in any uniform or non-uniform manner as desired. For example, the layer of re-emitting semiconductor construction material can be a plurality of regions having a non-uniform density gradient along the surface or region. This region may have any constant or non-uniform shape.

The structured re-emitting semiconductor construction layer can be constructed in a number of ways to provide performance gains, as described below. When many types of re-emitting semiconductor constructions are used to provide wider or more spectral output, light from short-wavelength re-emitting semiconductor constructions can be absorbed by other re-emitting semiconductor constructions. The pattern comprising separate lines or separated regions of each type of re-emitting semiconductor construction reduces the amount of reabsorption. This will be particularly effective in cavity configurations where pump light that has not been absorbed is reflected back into the re-emitting semiconductor construction pattern.

A first optical component comprising a re-emitting semiconductor construction / reflector assembly may then be attached to the LED base, and the heat sink may optionally include a transparent heat sink, which includes the re-emitting semiconductor component layer and interference Embodiments in which a filter can be attached are disclosed herein. The transparent heat sink may be a sapphire layer disposed between the re-emitting semiconductor construction layer / interference filter and the LED base. Most glasses have higher thermal conductivity than polymers and can likewise be useful for this function. The thermal conductivity of many other crystalline materials is higher than most glasses and can also be used here. The sapphire layer can be contacted at the edge by a metal heat sink.

The lifetime of the SP or LP filter is preferably greater than or equal to the lifetime of the LEDs in the same system. Degradation of the polymer interference filter may be due to overheating, which can result in material creep that changes the layer thickness value and thus the wavelength that the filter reflects. In the worst case, overheating melts the polymeric material, leading to rapid flow of the material and changes in wavelength selection as well as causing nonuniformity in the filter.

Degradation of the polymeric material may also be induced by short wavelength (chemical) radiation such as blue, purple or UV radiation, depending on the polymeric material. The rate of degradation depends on both the chemical light flux and the temperature of the polymer. Both temperature and flux generally decrease as the distance from the LED increases. Thus, in the case of high brightness LEDs, especially UV LEDs, it is advantageous to place the polymer filter away from the LED as far as the design allows. Placing the polymer filter on a transparent heat sink as described above can also improve the life of the filter. For domed filters, the flux of actinic radiation decreases with the square of the distance from the LED. For example, a hemispherical MOF reflector with a radius of 1 cm with a unidirectional 1 watt LED placed in the center of curvature will have an average intensity of 1 / (2π) W / cm 2 (surface area of the dome = 2π cm 2). At a radius of 0.5 cm, the average strength of the dome is 4 times that value or 2 / π W / cm 2. The system of LEDs, re-emitting semiconductor constructions, and multilayer optical films can be designed taking into account light flux and temperature control.

The reflective polarizer may be disposed adjacent to the multilayer reflector and / or adjacent to the re-emitting semiconductor construction material. Reflective polarizers allow light of a desired polarization to be emitted while reflecting other polarizations. Re-emitting semiconductor construction layers and other film components known in the art can polarize depolarized light reflected by reflective polarizers and are combined with re-emitting semiconductor construction layers or multilayer reflectors Light may be regenerated by the reflection of the layer to increase the brightness of the polarized light of the solid state optical device (LED). Suitable reflective polarizers include, for example, cholesteric reflective polarizers, cholesteric reflective polarizers with quarter wave retarders, DBEF reflective polarizers available from 3M Company, or DRPF reflective polarizers also available from 3M Company. . The reflective polarizer preferably polarizes the light emitted by the re-emitting semiconductor construction over a significant wavelength and angular range and can likewise reflect the LED emission wavelength range when the LED emits blue light.

Suitable multilayer reflector films are birefringent multilayer optical films, where the refractive index in the thickness direction of two adjacent layers is substantially matched and has a Brewster angle (an angle at which the reflectance of p-polarized light becomes zero) that is very large or nonexistent. . This allows the construction of multilayer mirrors and polarizers whose reflectivity to p-polarized light slowly decreases with, or is independent of, or increases with the angle of incidence away from the normal. As a result, a multilayer film with high reflectivity can be achieved over a wide bandwidth (both in the polarization plane for any direction of incidence for the mirror and for the selected direction for the polarizer). These polymeric multilayer reflectors include alternating layers of first and second thermoplastic polymers. This alternating layer forms a local coordinate system with x and y axes perpendicular to each other extending parallel to this layer and z axis perpendicular to the x and y axes, where at least some of the layers are birefringent. The absolute value of the difference in refractive index between the first and second layers is Δx, Δy and Δz for light polarized along the mutually perpendicular first, second and third axes, respectively. The third axis is perpendicular to the plane of the film, where Δx is greater than about 0.05 and Δz is less than about 0.05. These films are described, for example, in US Pat. No. 5,882,774, which is incorporated herein by reference.

15 is a schematic cross-sectional view of another embodiment of the present invention, namely device 210. Although non-planar multilayer reflector 224 is shown adjacent to re-emitting semiconductor construction 222, non-planar multilayer reflector 224 allows light to travel between re-emitting semiconductor construction 222 and multilayer reflector 224. Just be located. Non-planar multilayer reflector 224 reflects LED excitation light, such as UV or blue light, and transmits visible light. This non-planar multilayer reflector 224 may be referred to as a long pass (LP) reflector as described above. The arrangement above can be disposed in an optically transparent material 220.

Non-planar multilayer reflector 224 may be positioned to receive light from LED 212 as described herein. Non-planar multilayer reflector 224 can be any available thickness. Non-planar polymeric multilayer reflector 224 may be between 5 and 200 micrometers or between 10 and 100 micrometers in thickness. Non-planar multilayer reflector 224 may optionally be substantially free of inorganic material.

Non-planar multilayer reflector 224 may be formed of a material that resists degradation when exposed to UV, blue light, or violet light, as described herein. The multilayer reflector described herein can be stable under high intensity illumination for a long time. High intensity illumination can generally be defined as a flux level of 1 to 100 W / cm 2. The operating temperature at the interference reflector may be 100 ° C. or less, or 65 ° C. or less. Suitable exemplary polymeric materials include, for example, UV resistant materials formed from acrylic materials, PET materials, PMMA materials, polystyrene materials, polycarbonate materials, THV materials available from 3M (St. Paul, MN), and combinations thereof. It may include. These materials and PEN materials can be used as blue excitation light.

Non-planar multilayer reflector 224 may have a non-uniform thickness or thickness gradient along its length, width, or both. The non-planar multilayer reflector 224 may have a first thickness in the inner region 223 of the non-planar multilayer reflector 224 and a second thickness in the outer region 225 of the non-planar multilayer reflector 224. . The difference in thickness across the surface of the reflector is related to the corresponding difference or shift in the spectral reflectivity and the thin areas are blue shifted relative to the thick areas. There are various ways in which thickness gradients can be created. For example, the thickness gradient may be formed by thermoforming, embossing, laser embossing, extrusion, or the like, to name a few.

As shown in FIG. 15, the thickness of the inner region 223 may be greater than the thickness of the outer region 225. Increasing the thickness of the interior region 223 may reduce the undesirable effect known as the "halo effect". "Halo effect" is a problem known in the art that the balance of blue excitation light and yellow conversion light changes as a function of the viewing angle of the LED. Here, the thickness of the inner region 223 may be greater than the thickness of the outer region 225 to reduce the axial blue transmission.

As shown in FIG. 16, the thickness of the outer region 325 may be greater than the thickness of the inner region 323. The arrangement can be disposed within the optically transparent material 320.

The non-planar multilayer reflector can be located in any available configuration with LEDs as described herein. In an exemplary embodiment, the non-planar multilayer reflector is located between the re-emitting semiconductor construction and the LED (see, eg, FIG. 17). In another exemplary embodiment, the re-emitting semiconductor construction is located between the non-planar multilayer reflector and the LED (see, eg, FIGS. 15 and 16).

The non-planar multilayer reflector 224/324 can be configured to reflect UV or blue light and transmit at least a portion of the visible light spectrum, such as green light, yellow light or red light. In another exemplary embodiment, the non-planar multilayer reflector 224/324 can be configured to reflect UV, blue or green light and transmit at least a portion of the visible light spectrum, such as yellow or red light.

Re-emitting semiconductor construction 222/322 can emit visible light when illuminated with excitation light emitted from LEDs 212/312. The re-emitting semiconductor construction material can be any available thickness.

17 is a schematic cross-sectional view of another embodiment of an element 410 of the present invention. Although non-planar multilayer reflector 426 is shown adjacent to re-emitting semiconductor construction 422, non-planar multilayer reflector 426 allows light to travel between re-emitting semiconductor construction 422 and non-planar multilayer reflector 426. All you have to do is place it. Non-planar multilayer reflector 426 reflects visible light and transmits LED excitation light, such as UV or blue light, for example. This non-planar multilayer reflector 426 may be referred to as a short pass SP reflector as described above. The arrangement above may be disposed in an optically transparent material 420.

Non-planar multilayer reflector 426 may comprise the same material and may be formed in a similar manner to non-planar multilayer reflector 424 described above. Re-emitting semiconductor construction layer 422 is also described above.

Non-planar multilayer reflector 426 may be located in any available configuration with LEDs 412 as described herein. In the exemplary embodiment shown in FIG. 17, a non-planar multilayer reflector 426 is positioned between the re-emitting semiconductor construction 422 and the LED 412. In another exemplary embodiment, the re-emitting semiconductor construction 422 is positioned between the non-planar multilayer reflector 426 and the LED 412. In an alternative embodiment, the non-planar multilayer reflector 426 is hemispherical concave toward the LED 412. Such a design allows the light emitted by the LED 412 to strike the non-planar multilayer reflector 426 at a vertical or near vertical angle of incidence. The non-planar geometry of the multilayer reflector 426 allows this light to pass through the non-planar multilayer reflector 426 regardless of the side or direction in which substantially all shortwave light diverges from the LED 412.

18 is a schematic cross-sectional view of another embodiment of an element 510 of the present invention. Although the first non-planar multilayer reflector 524 is shown spaced apart from the re-emitting semiconductor construction 522, the first non-planar multilayer reflector 524 has light reflected from the re-emitting semiconductor construction 522 and the first non-planar multilayer. It only needs to be positioned so that it can travel between the reflectors 524. The first non-planar multilayer reflector 524 reflects LED excitation light, such as for example UV or blue light, and transmits visible light. The first non-planar multilayer reflector 524 may be referred to as a long pass (LP) reflector as described above. The arrangement can be disposed within the optically transparent material 520.

While the second non-planar multilayer reflector 526 is shown adjacent to the re-emitting semiconductor construction material 22, the second non-planar multilayer reflector 526 has no light emitting the re-emitting semiconductor construction material 522 and the second non-planar construction. It only needs to be positioned so that it can run between the multilayer reflectors 526. The second non-planar multilayer reflector 526 reflects visible light and transmits LED excitation light, for example UV or blue light. The second non-planar multilayer reflector 526 may be referred to as a short pass SP reflector as described above.

Re-emitting semiconductor construction 522 is shown disposed between first non-planar polymeric multilayer reflector 524 and second non-planar polymeric multilayer reflector 526. Re-emitting semiconductor construction 522 is described above.

19 is a schematic cross-sectional view of another embodiment of an element 610 of the present invention. While the first non-planar multilayer reflector 624 is shown adjacent to the re-emitting semiconductor construction material 622, the first non-planar multilayer reflector 624 has no light from the re-emitting semiconductor construction material 622 and the first non-planar construction. It only needs to be positioned so that it can run between the multilayer reflectors 624. The first non-planar multilayer reflector 624 reflects LED excitation light, such as, for example, UV or blue light, and transmits visible light. The first non-planar multilayer reflector 624 may be referred to as a long pass (LP) reflector as described above. The arrangement above may be disposed in an optically transparent material 620.

While the second non-planar multilayer reflector 626 is shown adjacent to the re-emitting semiconductor construction material 622, the second non-planar multilayer reflector 626 has the light re-emitting semiconductor construction material 622 and the second non-planar construction. It only needs to be positioned so that it can run between the multilayer reflectors 626. The second non-planar multilayer reflector 626 reflects visible light and transmits LED excitation light, such as, for example, UV or blue light. The second non-planar multilayer reflector 626 may be referred to as a short pass SP reflector as described above.

The re-emitting semiconductor construction layer 622 is shown disposed between the first non-planar multilayer reflector 624 and the second non-planar multilayer reflector 626. Re-emitting semiconductor construction 622 is described above.

The device according to the invention is a graphic display device, for example a large or small screen video monitor, a computer monitor or display, a television, a telephone or telephone display, a personal digital assistant or personal digital assistant display, a pager or pager display, a calculator or Calculator display, 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 a component or an essential component such as a traffic controller display, an advertisement display, or an advertisement sign.

The device according to the invention can be such as a component or an essential component of a liquid crystal display (LCD) or similar display, ie a backlight for such a display. In one embodiment, the semiconductor device according to the invention is particularly adapted for use as a backlight for liquid crystal displays by matching the color emitted by the semiconductor device according to the invention to the color filter of the LCD display.

The device according to the invention is a lighting device, for example a self-supporting or built-in lighting fixture or lamp, a landscape or architectural lighting fixture, a handheld or vehicle mounted lamp, an automobile headlight or taillight, an automobile interior lighting fixture, a car or other than Components or essential components such as signals for use, road lighting devices, traffic control signals, ship lamps or signals or interior lighting equipment, aircraft lamps or signals or interior lighting equipment, large or small equipment or large or small equipment lamps; Or any device or component used as an infrared, visible or ultraviolet 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 exemplary embodiments described above.

Claims (28)

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 c) a reflector positioned to reflect light emitted from the LED onto the re-emitting semiconductor construction. The device of claim 1, wherein the re-emitting semiconductor construction further comprises an absorbing layer immediately adjacent or immediately adjacent to at least one of the at least one potential wells. The device of claim 1, wherein the at least one potential well comprises a quantum well. The device of claim 1, wherein the reflector is a multilayer reflector. The device of claim 1, wherein the reflector is a non-planar flexible multilayer reflector. The device of claim 1, wherein the reflector is a reflective polarizer layer. A graphic display device comprising the device of claim 1. Lighting device comprising the device according to claim 1. The device of claim 1, wherein the re-emitting semiconductor construction can emit light of a second wavelength and the reflector reflects light of the first wavelength and transmits light of the second wavelength. 10. The reflector of claim 9, wherein the reflector is an interference reflector positioned proximate to the re-emitting semiconductor construction, the device further comprising a TIR facilitating layer immediately adjacent the re-emitting semiconductor construction, wherein the TIR facilitating layer comprises a first refractive index at the first wavelength. And a second refractive index that is less than the first refractive index at the second wavelength. a) an LED capable of emitting light of a first wavelength; b) a re-emitting semiconductor construction comprising at least one potential well that can emit light of a second wavelength and is not located within a pn junction; And c) a reflector that transmits light of the first wavelength and reflects at least a portion of the light of the second wavelength. 12. The device of claim 11, wherein the re-emitting semiconductor construction further comprises an absorbing layer adjacent or immediately adjacent to at least one of the at least one potential wells. The device of claim 11, wherein the at least one potential well comprises a quantum well. The device of claim 11, wherein the reflector is located between the LED and the re-emitting semiconductor construction. The device of claim 11, wherein the reflector is a multilayer reflector. The device of claim 11, wherein the reflector is a non-planar flexible multilayer reflector. Graphic display device comprising the device according to claim 11. Lighting device comprising the device according to claim 11. a) i) a first potential well located within the pn junction and constituting an LED capable of emitting light of a first wavelength, and ii) a semiconductor unit comprising a second potential well that is not located within a pn junction and constitutes a re-emitting semiconductor construction; And b) a reflector positioned to reflect light emitted from the LED onto the re-emitting semiconductor construction. 20. The device of claim 19, wherein the re-emitting semiconductor construction further comprises an absorbing layer adjacent or immediately adjacent to at least one of the at least one potential wells. The device of claim 19, wherein the at least one potential well comprises a quantum well. 20. The device of claim 19, wherein the re-emitting semiconductor construction can emit light of a second wavelength, and a reflector reflects light of the first wavelength and transmits light of the second wavelength. 23. The device of claim 22, wherein the reflector is an interference reflector positioned proximate to the re-emitting semiconductor construction, the device further comprising a TIR facilitating layer immediately adjacent the re-emitting semiconductor construction, wherein the TIR facilitating layer comprises a first refractive index at the first wavelength. And a second refractive index that is less than the first refractive index at the second wavelength. The device of claim 19, wherein the reflector is a multilayer reflector. 20. The device of claim 19, wherein the reflector is a non-planar flexible multilayer reflector. The device of claim 19, wherein the reflector is a reflective polarizer layer. 20. Graphic display device comprising the device according to claim 19. Lighting device comprising the device according to claim 19.

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