Phosphor material for light sources and method for fluidizing same

Abstract

The present invention provides a method comprising obtaining a potassium hexafluorosilicate (PFS)-based powder, obtaining a fluidizing material, and mixing the PFS-based powder with the fluidizing material to form a PFS-based mixture. The PFS-based mixture is configured to be mixed with a resin material to form a flowing phosphor blend, the phosphor blend being configured to be placed onto a light source to form a phosphor on the light source.

Description

[0001] This invention application is a divisional application of the invention patent application with international application number PCT / US2017 / 029534, international application date April 26, 2017, application number 201780027462.4 entering the Chinese national phase, and name “Phosphor material for light source and method for fluidizing the same”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This patent application claims priority to U.S. Provisional Application No. 62 / 330,401, filed on May 2, 2016, the entire disclosure of which is incorporated herein by reference. Background Art

[0004] Some light sources include phosphor bodies disposed on or near the light sources. These phosphor bodies or phosphors receive at least some of the light generated by the light source. The received light causes the phosphor to emit light. For example, some light emitting diodes (LEDs) include phosphors that emit red light, which receive light generated by the LED to emit light.

[0005] To make phosphors, potassium hexafluorosilicate (PFS) based materials can be blended with silicone. The blended mixture is then placed on an LED and cured to form the phosphor. One problem that can occur in blending PFS based materials with silicone is that the PFS based materials aggregate into larger clumps. For example, the PFS based material can be in the form of a powder that is mixed with silicone. During the process of mixing the PFS based powder into the silicone, the powder can aggregate into larger clumps. Electrostatic forces can cause this aggregation of the PFS based powder.

[0006] These clumps can cause problems with the phosphor and the formation of the phosphor. The clumps of PFS-based powder can reduce the amount of PFS material that receives light from the light source because only the outer surface area of ​​the larger clumps can receive light, while the interior of the clumps cannot receive light. As a result, the amount of light received by the PFS material to generate light emitted from the phosphor including the PFS material is reduced (relative to a phosphor without clumps or with smaller aggregates of PFS material). During phosphor formation, the PFS and silicone blend can be dispensed through a nozzle or other device with a relatively small opening. Clumps or other aggregates of PFS material in the blend can block or otherwise impede the flow of the blend through and out of the nozzle onto the LED, thereby interfering with the formation of the phosphor. In addition, larger clumps of PFS-based powder can reduce the ability of the phosphor to dissipate heat (relative to a phosphor without clumps or with smaller clumps) and reduce the useful life of the phosphor. Summary of the invention

[0007] In one embodiment, the present invention provides a method comprising obtaining a potassium hexafluorosilicate (PFS)-based powder, obtaining a fluidized material, and mixing the PFS-based powder with the fluidized material to form a PFS-based mixture. The PFS-based mixture is configured to be mixed with a resin material to form a flowing phosphor blend, and the phosphor blend is configured to be placed on a light source to form a phosphor on the light source.

[0008] In another embodiment, the present invention provides a method comprising obtaining a potassium hexafluorosilicate (PFS)-based powder, obtaining a metal oxide fluidizing material, and mixing the PFS-based powder with the metal oxide fluidizing material to form a PFS-based mixture. The PFS-based mixture is configured to be mixed with a resin material to form a phosphor blend, the phosphor blend being configured to form a phosphor of a light source.

[0009] In one embodiment, the present invention provides a phosphor body formed of a potassium hexafluorosilicate (PFS) based powder, a metal oxide fluidizing material, and a resin material. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The subject matter described in this specification will be better understood by reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0011] Figure 1 A flow chart illustrating one embodiment of a method for fluidizing a phosphor material, and optionally using the fluidized phosphor material for producing a phosphor;

[0012] Figure 2 shows mixing of a PFS-based material with a fluidizing material to form a fluidized PFS-based mixture according to one embodiment;

[0013] Figure 3 It is shown that according to one embodiment, Figure 2 The mixing of the fluidized PFS-based mixture and the resin material shown in FIG.

[0014] Figure 4 According to one embodiment, Figure 3 placing the phosphor blend shown in onto a light source; and

[0015] Figure 5 For different weight percentages of fluidizing material in the PFS-based mixture, Figure 2 The bulk density of the PFS-based mixture and the internal quantum yield or quantum efficiency (QY) of the PFS-based mixture are shown in FIG. DETAILED DESCRIPTION

[0016] Figure 1FIG. 1 is a flow chart of one embodiment of a method 100 for fluidizing a phosphor material and optionally producing a phosphor using the fluidized phosphor material. At 102, a PFS-based powder is obtained. The PFS-based powder may be doped with tetravalent manganese (Mn 4+ ). Alternatively, another type of phosphor material may be obtained. When the PFS-based material is obtained by decomposing a larger solid body of the PFS-based material, such as by grinding or crushing the larger solid body, the PFS-based material may be in the form of a powder. In one embodiment, the PFS-based material may be in the form of a powder when it has an average or median maximum external non-circumferential dimension or diameter of no greater than one tenth of a millimeter.

[0017] At 104, a fluidized material is obtained. In one embodiment, the fluidized material comprises a metal oxide powder. For example, the fluidized material may comprise aluminum oxide. Alternatively, the fluidized material may comprise another metal oxide powder or a material such as silicon dioxide or fumed silicon dioxide. When the particles of the fluidized material have a very small size, such as an average or median maximum external non-circumferential dimension or diameter of less than one micron, the fluidized material may be provided in powder form.

[0018] At 106 , the fluidized material is mixed with a PFS-based powder to form a PFS-based mixture. Figure 2 2 shows the mixing of a PFS-based material 200 and a fluidizing material 202 to form a fluidized PFS-based mixture 204 according to one embodiment. The amount of fluidizing material 202 mixed into the PFS-based material 200 may be relatively small. For example, the total weight of the fluidizing material 202 mixed with the PFS-based material 200 may be no greater than 0.1% of the weight of the PFS-based material 200. Alternatively, the total weight of the fluidizing material 202 mixed with the PFS-based material 200 may be no greater than 0.08%, no greater than 0.06%, no greater than 0.05%, no greater than 0.04%, no greater than 0.03%, or no greater than 0.02% of the weight of the PFS-based material 200.

[0019] The method 100 optionally includes, at 108 , mixing the fluidized PFS-based mixture 204 with a resin material. Figure 3 According to one embodiment, Figure 2 300. The fluidized PFS-based mixture 204 and the resin material 300 are combined to form a flowing phosphor blend 302. The blend 302 can flow by being at least partially fluid until the blend 302 solidifies into a solid body. In one embodiment, the resin material 300 is a silicone, such as polydimethylsiloxane. Alternatively, another curable resin material can be used.

[0020] The method 100 optionally includes, at 110 , placing the phosphor blend onto a light source. Figure 4 4 shows that, according to one embodiment, phosphor blend 302 is placed onto light source 400. Phosphor blend 302 can be injected onto light source 400, such as a semiconductor-based light source (e.g., LED), by injecting blend 302 from reservoir 402 through nozzle 404 onto light source 400. Optionally, blend 302 can be sprayed or otherwise dispensed from nozzle 404. Figure 4 As shown, the blend 302 can at least partially encapsulate the light source 400. The blend 302 can then be cured to harden on or over the light source 400. The cured blend 302 forms a phosphor or phosphor body on the light source 400 that emits light in response to receiving light generated by the light source 400.

[0021] The nozzle 404 may have a relatively small outlet or orifice through which the blend 302 exits the nozzle 404. The outlet may have a diameter of 70 microns or less. If the fluidizing material 202 is not added to the PFS-based material 200, particles of the PFS-based material 200 in the blend 302 may clog the outlet of the nozzle 404 and prevent additional blend 302 from being dispensed from the nozzle 404. Adding the fluidizing material 202 to the PFS-based material 200 prevents such clogging from occurring.

[0022] Adding the fluidizing material 202 to the PFS-based material 200 may increase the loose bulk density or tapped density of the fluidized PFS-based mixture 204 , even when a relatively small amount of the fluidizing material 202 is present. Figure 5 The bulk density 500 of the PFS-based material 200 in the PFS-based mixture 204 and the internal quantum yield or quantum efficiency (QY) 502 of the PFS-based mixture 204 are shown for different weight percentages of the fluidizing material 202 in the mixture 204. The internal quantum yield or efficiency can represent the ratio of the number of photons leaving the sample of the PFS-based mixture / the number of photons absorbed by the sample. The internal quantum yield or efficiency can be measured by an FS5 fluorescence spectrophotometer using an integrating sphere manufactured by Edinburgh Instruments. Figure 5 In the example shown, the PFS-based material 200 is potassium hexafluorosilicate doped with tetravalent manganese, and the fluidizing material 202 is alumina.

[0023] The bulk density 500 and quantum yield 502 are shown next to a horizontal axis 504 representing different weight percentages of aluminum oxide in the mixture 204, and a first vertical axis 506 and a second vertical axis 508 representing different bulk densities and different internal quantum yields or efficiencies.

[0024] like Figure 5 As shown, even in relatively small amounts (e.g., at 0.005% by weight), adding the fluidizing material 202 to the PFS-based material 200 increases the bulk density 500 of the PFS-based material 200. As the amount of the fluidizing material 202 added to the PFS-based mixture 204 increases (e.g., an amount of 0.03% to 0.07% by weight), the bulk density 500 becomes constant or substantially constant and is approximately 20% greater than the bulk density 500 without adding the fluidizing material 202 to the PFS-based material 200. Within the measurement error of the powder, the quantum efficiency 502 of the PFS-based mixture 204 is constant or substantially constant within this range.

[0025] Unless otherwise defined, the technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present disclosure belongs. The terms "first", "second", etc. used herein do not represent any order, quantity, or importance, but are used to distinguish an element from another element. In addition, the terms "one" and "a kind of" do not represent quantitative restrictions, but represent the presence of at least one of the cited items. The use of "including", "comprising" or "having" and its variations in this article is intended to cover the items listed thereafter and their equivalents, as well as other items. The terms "connect" and "couple" are not limited to physical or mechanical connections or connections, and may include electrical and optical connections or connections, whether direct or indirect.

[0026] In addition, the skilled person will recognize the interchangeability of various features from different embodiments. Those of ordinary skill in the art can mix and match the various features described, as well as other known equivalents for each feature, to construct additional systems and techniques in accordance with the principles of the present disclosure.

[0027] When describing the alternative embodiments of the claimed device, specific terms are used for clarity. However, the present invention is not intended to be limited to the specific terms so selected. Therefore, it should be understood that each specific element includes all technical equivalents that operate in a similar manner to achieve similar functions.

[0028] It should be noted that the various non-limiting embodiments described and claimed herein may be used separately, in combination, or selectively combined for specific applications.

[0029] Furthermore, some of the various features of the above-described non-limiting embodiments may be used to advantage without the corresponding use of other described features.Thus, the foregoing description should be considered merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.

[0030] The following claim limitations are not written in means-plus-function format and are not intended to be interpreted under 35 USC §112(f) unless and until such claim limitations expressly use the phrase "means" followed by a recitation of function absent further structure.

Claims

1. A method for forming a phosphor body, the method comprising: mixing a potassium hexafluorosilicate-based powder with a metal oxide fluidizing material to form a potassium hexafluorosilicate-based mixture, wherein the fluidizing material comprises aluminum oxide, wherein the potassium hexafluorosilicate-based mixture is configured to be mixed with a resin material to form a flowing phosphor blend, and the phosphor blend is configured to be placed onto a light source to form a phosphor body on the light source, The fluidizing material is present in an amount of 0.03 wt % to 0.07 wt % relative to the weight of the potassium hexafluorosilicate-based mixture.

2. The method of claim 1, wherein the potassium hexafluorosilicate-based powder comprises potassium hexafluorosilicate doped with manganese.

3. The method according to claim 2, wherein the manganese comprises Mn 4+ . The method of claim 1 , wherein the fluidized material comprises a metal oxide powder.

5. The method of claim 1, wherein the fluidizing material comprises silicon dioxide.

6. The method of claim 1, wherein the fluidized material is formed into submicron sized particles. The method of claim 1 , wherein the resin material comprises silicone.

8. The method of claim 1, wherein the phosphor formed from the phosphor blend has a greater quantum efficiency relative to a phosphor formed from a phosphor blend including the potassium hexafluorosilicate-based powder and a resin material and not including the fluidizing material.

9. A method for forming a phosphor body, the method comprising: A potassium hexafluorosilicate-based powder is mixed with a metal oxide fluidizing material to form a potassium hexafluorosilicate-based mixture, wherein the fluidizing material includes aluminum oxide, wherein the potassium hexafluorosilicate-based mixture is configured to be mixed with a resin material to form a flowing phosphor blend, the flowing phosphor blend is configured to form a phosphor body of a light source, and wherein the metal oxide fluidizing material is present in an amount of 0.03 wt % to 0.07 wt % relative to the weight of the potassium hexafluorosilicate-based mixture.

10. The method of claim 9, further comprising placing the flowing phosphor blend onto the light source to form the phosphor body on the light source.

11. The method of claim 9, wherein the potassium hexafluorosilicate-based powder comprises potassium hexafluorosilicate doped with manganese.

12. The method according to claim 11, wherein the manganese comprises Mn 4+ .

13. The method of claim 9, wherein the metal oxide fluidizing material is formed into submicron sized particles. The method of claim 9 , wherein the resin material comprises silicone.

15. The method of claim 9, wherein the phosphor formed from the phosphor blend has a greater quantum efficiency relative to a phosphor formed from a phosphor blend including the potassium hexafluorosilicate-based powder and a resin material and not including the metal oxide fluidizing material.

16. A phosphor body formed from: Potassium hexafluorosilicate based powder; a metal oxide fluidizing material, wherein the fluidizing material comprises aluminum oxide; and Resin material, The metal oxide fluidizing material is present in an amount of 0.03 wt % to 0.07 wt % relative to the weight of the potassium hexafluorosilicate-based mixture.

17. The phosphor body of claim 16, wherein the potassium hexafluorosilicate-based powder comprises potassium hexafluorosilicate doped with manganese.

18. The phosphor body of claim 17, wherein the manganese comprises Mn 4+ .

19. The phosphor body of claim 16, wherein the metal oxide fluidizing material is formed into sub-micron sized particles.

20. The phosphor body of claim 16, wherein the resin material comprises silicone.

21. The phosphor body of claim 16, wherein the phosphor body has a greater quantum efficiency relative to another phosphor body formed from a phosphor blend including the potassium hexafluorosilicate-based powder and a resin material and excluding the metal oxide fluidizing material.

22. A method for manufacturing a light source, the method comprising: obtaining a flowing phosphor blend of a mixture of a potassium hexafluorosilicate-based powder, a metal oxide fluidizing material, and a resin material, the blend configured to be placed onto a light source to form a phosphor body on the light source, wherein the fluidizing material includes aluminum oxide; and dispensing the flowing phosphor blend from a nozzle onto the light source, The metal oxide fluidizing material is present in an amount of 0.03 wt % to 0.07 wt % relative to the weight of the potassium hexafluorosilicate-based mixture.

23. The method of claim 22, wherein the nozzle has an outlet through which the flowing phosphor blend is dispensed, the outlet having an opening no greater than 70 microns.

Images