Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
  • F21V9/40—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters with provision for controlling spectral properties, e.g. colour, or intensity
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
  • C09K11/61—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
  • C09K11/61—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing fluorine, chlorine, bromine, iodine or unspecified halogen elements
  • C09K11/617—Silicates
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
  • C09K11/64—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing aluminium
  • C09K11/644—Halogenides
  • C09K11/645—Halogenides with alkali or alkaline earth metals
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/01—Manufacture or treatment
  • H10H20/036—Manufacture or treatment of packages
  • H10H20/0361—Manufacture or treatment of packages of wavelength conversion means
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/851—Wavelength conversion means
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/851—Wavelength conversion means
  • H10H20/8511—Wavelength conversion means characterised by their material, e.g. binder
  • H10H20/8512—Wavelength conversion materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W90/00—Package configurations
  • H10W90/701—Package configurations characterised by the relative positions of pads or connectors relative to package parts
  • H10W90/751—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bond wires
  • H10W90/756—Package configurations characterised by the relative positions of pads or connectors relative to package parts of bond wires between a chip and a stacked lead frame, conducting package substrate or heat sink

Definitions

• the invention relates to a lighting device comprising a light source arranged to emit light with a primary wavelength, and a wavelength converting element arranged to convert at least part of the light with the primary wavelength into light with a secondary wavelength, the element comprising a phosphor with a metal-ion activator which is excitable via a partially forbidden electronic transition, said phosphor being compounded with a polymer.
• the invention also relates to a wavelength converting element suitable for use in such lighting device as well as to a method for the manufacture of a wavelength converting element.
• a lighting device of the type mentioned in the opening paragraph is known from the patent publication US 2010/0096974-A1.
• This document describes a device comprising a LED having an encapsulant, which acts as a wavelength converting element.
• Said encapsulant is formed as a shell of a suitable plastic or glass, in which a phosphor or a phosphor blend in particle form is dispersed.
• Said phosphor (blend) acts as a luminescent material that absorbs radiation energy in a portion of the electromagnetic spectrum and emits radiation energy in another portion of the electromagnetic spectrum. In this manner, (part of) the light with a primary wavelength emitted by the LED is converted into light with another (secondary) wavelength.
• phosphors with metal-ion activators which are to be excited via a partially forbidden absorption band show limited interaction with light of an appropriate wavelength.
• forbidden absorption bands are especially found in phosphors having a transition metal-ion activator in the host lattice. In these metals, specific d - d electronic transitions are forbidden.
• Such phosphors show relatively low absorbance upon interaction with light having a suitable wavelength. Nevertheless sufficient light conversion of the primary wavelength can be achieved when using relatively long interaction paths of the light with the primary wavelength through the converting element. In practice this solution implies rather thick elements. However, such long interaction paths usually gives rise to undesired large scattering losses.
• the invention particularly aims at providing a cheap lighting device having a light source and an efficient wavelength converting element with phosphors with a metal- ion activator which is excitable via a partially forbidden absorption. Especially the scattering losses in the converting element should be relatively low.
• Another object of the invention is providing an efficient wavelength converting element of the indicated type suitable for use in a lighting device as well as the manufacture of such wavelength converting element.
• a lighting device comprising 1) a light source arranged to emit light with a primary wavelength, and 2) a wavelength converting element arranged to convert at least part of the light with the primary wavelength into light with a secondary wavelength, the element comprising a phosphor with a metal-ion activator which is excitable via a partially forbidden electronic transition, said phosphor being compounded with a polymer, the phosphor and the polymer being chosen such that the difference in their refractive index is smaller than 0.1.
• the invention is based on the insight gained by the inventors that the undesired scattering in converting elements can be significantly reduced by compounding the phosphor in a polymer having a refractive index which is closely matched to the one of the phosphor.
• the refractive index difference is smaller than 0.1.
• the difference in the refractive index of the phosphor and the refractive index of the polymer is smaller than 0.05, whereas a difference smaller than 0.03 is more preferred.
• the best lighting devices of the desired type are those in which the refractive index difference is smaller than 0.02. It generally holds that a smaller refractive index difference means lower scattering losses in the wavelength converting element.
• the invention will function in all kind of lighting devices having a light source emitting light with a primary wavelength and a phosphor for (partly) converting the wavelength of this light, such as for example TL-tubes.
• a light source emitting light with a primary wavelength and a phosphor for (partly) converting the wavelength of this light such as for example TL-tubes.
• the wavelength converting element in the invented lighting device can comprise a single phosphor, but also multiple phosphors. If two or more phosphors are used, at least one of them should have a metal- ion activator which is excitable via a partially forbidden transition. Multiple phosphors are especially useful when designing lighting devices which should emit white light.
• the phosphor comprises a Mn(IV)-activated fluoride compound.
• the Mn(IV) transition metal- ion is located in a specific coordination site in the crystalline host lattice. Here it functions as an activator, which has to be excited via a partially forbidden d - d transition.
• phosphors having a fluoride-based host lattices show relatively small refractive indexes. In combination with a well-chosen polymer material, a good match of the refractive indexes can be obtained, so that the refractive index difference is rather small, i.e. smaller than 0.1.
• Mn(IV)-activated fluoride compound are preferred over other known phosphor compounds, like Cr(III)- or Eu(III)- activated crystalline phosphor compounds, as the Mn(IV) compounds show an interesting emission line pattern in the red area of the electromagnetic spectrum and moreover have a relatively good exitability in the blue area of the spectrum.
• Mn(IV)-activated fluoride compound comprises at least one of K 2 SiF 6 :Mn(IV) and
• a person skilled in the art knows that small amounts of the chemical elements in these crystalline compounds can be replaced by other elements. This is due either to impurities in the starting materials or to a deliberate choice in order to adjust the properties of these compounds.
• Compounds of these types are interesting as, in combination with other phosphor compounds, relatively cheap lighting devices can be manufactured having a warm white spectrum at correlated color temperatures ⁇ 3000K with high color rendition (Ras > 80 and positive R9).
• the other phosphor compounds should emit in the yellow to green part of the electromagnetic spectrum.
• Y 3 Al50i 2 :Ce or Lu 3 Al50i 2 :Ce (or known variations thereof) are good candidates for such other phosphor compounds.
• the polymer is a fluorine-containing polymer.
• Polymers of this type can be used with great advantage when compounded with phosphors having a metal-ion activator which is excitable via a partially forbidden electronic transition.
• phosphors comprising a Mn(IV)-activated fluoride compound such as compounds of the type K 2 SiF 6 :Mn(IV) and Na 3 Li 3 Al 2 Fi 2 :Mn(IV)
• the refractive index of these phosphors and polymers match rather well. Wavelength converting elements comprising a phosphor as described before, being compounded with an organic polymer as described before appear to be quite transparent and therefore show unexpected low scattering.
• the polymer is a copolymer comprising at least two of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride.
• the refractive index of the resulting co-polymer can be nicely adjusted to a desired value, especially to the value of the refractive index of the phosphor compound to be mixed with the polymer.
• the lighting device according to the invention in which the polymer is a co-polymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride.
• a skilled person can without any inventive action select the right amounts of these three fluoropolymer precursors in order to design a co-polymer with a desired refractive index.
• the amount of phosphor in the polymer ranges from 10 - 20 vol.%.
• a phosphor amount smaller than 10 vol.% causes that the conversion elements should be designed rather thick (> 2 mm) in order to obtain a sufficient conversion efficiency.
• Phosphor amounts in the polymer larger than 20 vol.% results in converting elements having a thickness lower than 0.1 mm, which elements are difficult to handle in practice.
• Optimal amounts of the phosphor in the polymer range from 13 - 17 vol.%. Using these amounts, converting elements can be manufactured having an optimal combination of thickness and absorption efficiency.
• a lighting device shows the feature that it comprises at least two light sources and that the wavelength converting element is arranged remotely from the light sources.
• a lighting device may comprise more than one wavelength converting element.
• the present invention can be applied in lighting devices of which the wavelength converting element is proximate to the light source, usually a LED.
• the wavelength converting element is in direct contact with the LED and may be shaped to form an optical lens.
• the invention can however also be applied in lighting devices in which the wavelength converting element is in the vicinity of the light source (LED).
• the converting element can be present as a layer on the exterior of an optical lens, which lens is in direct contact with the LED.
• the present invention can however also be applied with great advantage in a lighting device having multiple LEDs wherein the converting element is arranged remotely from these LEDs.
• the converting element preferably has the shape of a plate and is positioned at a distance from the light sources.
• the invention relates also to a wavelength converting element, which is suitable for use in a lighting device. More particularly, such element according to the invention comprises a phosphor with a metal-ion activator which is excitable via a partially forbidden electronic transition, said phosphor being compounded with a polymer, the phosphor and the polymer being chosen such that the difference in their refractive index is smaller than 0.1.
• Said phosphor comprises preferably a Mn(IV)-activated fluoride compound, more preferably a compound comprising at least one of K 2 SiF 6 :Mn(IV) and
• the phosphor may also comprise a coating to increase the stability of the phosphor.
• the coating material consists substantially of a fluoride with very low solubility in water, such as calcium fluoride.
• Said polymer can be an inorganic polymer, but an organic polymer is preferred. Fluorine-containing polymers appear to be very useful, especially co-polymers comprising at least two of tetrafiuoroethylene, hexafluoropropylene and vinylidene fluoride.
• the wavelength converting element can be shaped as an optical element, particularly as a lens or as a plate.
• the invention further relates to a method for manufacturing a wavelength converting element.
• This invented method has the feature that the phosphor is compounded with the polymer, after which the compound is shaped into a wavelength converting element. Contrary to state of the art methods, the phosphor and (pre)polymer are after their mixing not cured 'in situ'.
• the mixture of phosphor and the already cured polymer is preferably prepared by extrusion or kneading.
• the shaping of the converting element is preferably performed by means of hot pressing or injection moulding.
• the elements manufactured according to this method can be applied with great advantage in a lighting device. BRIEF DESCRIPTION OF THE DRAWINGS
• Figure 1 shows a cross-section of a first embodiment of a lighting device according to the present invention
• Figure 2 shows a cross-section of a second embodiment of a lighting device according to the present invention.
• FIG. 1 illustrates in cross-section a first embodiment of the lighting device 1 according to the present invention.
• Said lighting device 1 comprises a light source 2, which is embodied as a light emitting diode (LED).
• LED light emitting diode
• Said light source 2 is positioned on a part 3 of a power lead 4, which, together with a further power lead 5, arranges for electrical current that causes the LED to emit radiation. This radiation is indicated by the arrows that point away from the LED.
• the power leads 4, 5 include thin conducting wires 6 which are directly connected to the LED.
• Light source 2 is encapsulated in a wavelength converting element 7, which has the shape of an optical lens.
• Converting element 7 is mainly composed of an organic polymer.
• a phosphor has been compounded with this polymer.
• Said phosphor contains a metal- ion activator which is excitable via a partially forbidden electronic transition.
• a Mn(IV)-activated fluoride compound was used as the phosphor, more particularly the compound Na 3 Li 3 Al 2 Fi 2 :Mn(rV).
• a fluorine-containing polymer was used as a matrix for the phosphor.
• the polymer used was a co-polymer of
• the difference in the refractive index of both constituents of the converting element was below 0.03. More precisely, the refractive index of the phosphor material has been measured to be 1.340 whereas the refractive index of the polymer material was matched to a value of 1.363. Due to the small difference in refractive indexes of both constituents (0.023), hardly or no scattering was observed in the converting element, even when the element had rather large dimensions of 10 mm (length) by 5 mm (cross section). So, an efficient absorption of the blue radiation of 450 nm was possible, which was converted by the wavelength converting element to radiation with a wavelength maximum of 650 nm.
• the wavelength converting element is positioned proximate to the light source 2 (here the LED).
• light source 2 is directly surrounded by the phosphor material.
• a converting element 7 shaped as an optical lens in which the phosphor is not proximate to but in the vicinity of the light source 2. In that situation, the phosphor is concentrated in a layer 8 at some distance from the light source 1.
• layer 8 functions as the wavelength converting element.
• the other part of the lens (outside layer 8) is substantially free of the phosphor.
• the complete lens may consist of the polymer material which matches with the phosphor. It is also possible that the part of the lens which is substantially free of the phosphor is composed of another polymer material, without departing from the present invention.
• Layer 8 should however contain a polymer having a refractive index as defined according to the present invention.
• the wavelength converting element 7 may comprise additional phosphors, which preferably should emit in the yellow to green part of the electromagnetic spectrum.
• additional phosphors Y 3 Al 5 0i2:Ce(III) or Lu 3 Al 5 0i2:Ce(III) (or known variations thereof) are good candidates for such additional phosphor compounds.
• Wavelength converting element with phosphor mixtures of these types are interesting as relatively cheap lighting devices with a warm white spectrum at correlated color temperatures ⁇ 3000K with high color rendition (Ras > 80 and positive R9) can be manufactured with such mixtures.
• Figure 2 illustrates in cross-section a second embodiment of the lighting device 1 according to the present invention.
• Device 1 comprises a plurality of light sources 2 (again embodied as LEDs), of which only five are shown in cross-section. These LEDs may emit radiation of the same or of different wavelength. The direction of the radiation is indicated by small arrows.
• the emitted light leaves the lighting device 1 via converting element 7, which is here formed as a plate.
• converting element 7 is here formed as a plate.
• the incident radiation is converted to radiation having a different wavelength.
• said optical plate is attached to a substrate 9 which is transparent to the (converted) radiation.
• the side-walls 10 and the bottom- wall 11 are provided with reflecting means, so that a large portion of the generated radiation leaves the lighting device 1 via the wavelength converting element 7. If LEDs are used which emit radiation with different wavelengths, color mixing can occur within the lighting device 1. In such device, it may be useful to apply a stack of wavelength converting elements 7, the individual elements being chosen for the different wavelengths emitted by the different LEDs.
• the wavelength converting element 7 comprises a polymer and a phosphor with a metal- ion activator which is excitable via a partially forbidden electronic transition. More precisely, the phosphor comprises a Mn(IV)-activated fluoride compound, more specifically the compound K 2 SiF 6 :Mn(IV).
• the polymer is a fluorine-containing polymer chosen from the class of organic polymers. More precisely, the polymer is a co-polymer comprising at least two of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (DyneonTM THV 2030 GZ). The mentioned phosphor has been compounded with the indicated polymer, starting with appr.
• the phosphor and polymer materials have been chosen such that the difference in their refractive index is smaller than 0.1. More precisely, the refractive index of the phosphor material has been determined to be 1.340 whereas the refractive index of the polymer material was matched to a value of 1.350. Due to the small difference is refractive indexes of both constituents
• the wavelength converting element according to the present invention was manufactured and shaped according to the invented method.
• a good combination of phosphor and polymer was determined. This means especially that the difference in refractive index between both substances should be small (smaller than 0.1, preferably smaller than 0.05 and more preferably smaller than 0.02).
• a certain volume amount of phosphor material and polymer material were combined and extruded or kneaded at a temperature below 200°C. Above this temperature, decomposition of the phosphor material is possible.
• the amount of phosphor in the polymer ranged between 10 and 20 vol%.
• the wavelength converting element was shaped as an optical lens or as an optical plate by means of hot pressing or injection moulding.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Engineering & Computer Science (AREA)
• Luminescent Compositions (AREA)
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• 2010
  • 2010-12-17 KR KR1020127018580A patent/KR20120115322A/ko not_active Ceased
  • 2010-12-17 CN CN201080057753.6A patent/CN102652166B/zh active Active
  • 2010-12-17 JP JP2012543986A patent/JP5795771B2/ja not_active Expired - Fee Related
  • 2010-12-17 US US13/509,802 patent/US9175214B2/en not_active Expired - Fee Related
  • 2010-12-17 WO PCT/IB2010/055905 patent/WO2011073951A2/en not_active Ceased
  • 2010-12-17 TW TW099144686A patent/TW201140890A/zh unknown
  • 2010-12-17 EP EP10812916.4A patent/EP2513246B1/en active Active

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