Solid-state light emitting devices and signage with photoluminescence wavelength conversion and photoluminescent compositions therefor
A photoluminescent composition (“phosphor ink”) comprises a suspension of particles of at least one blue light (380 nm to 480 nm) excitable phosphor material in a light transmissive liquid binder in which the weight loading of at least one phosphor material to binder material is in a range 40% to 75%. The binder can be U.V. curable, thermally curable, solvent based or a combination thereof and comprise a polymer resin; a monomer resin, an acrylic, a silicone or a fluorinated polymer. The composition can further comprise particles of a light reflective material suspended in the liquid binder. Photoluminescence wavelength conversion components; solid-state light emitting devices; light emitting signage surfaces and light emitting signage utilizing the composition are disclosed.
1. A method of manufacturing a photoluminescent wavelength conversion component for a solid-state light emitting device, comprising:
mixing a blue light excitable phosphor material and a light reflective material with a U.V. curable light transmissive binder to form a composition, wherein the blue light excitable phosphor material has an average particle size of 10 μm to 20 μm, wherein a weight percent loading of the light reflective material to the blue light excitable phosphor material is 0.01% to 10%, wherein the light reflective material has a particle size in a range of 0.1 μm to 10 μm, the blue light excitable phosphor material being excitable by light of wavelength 380 nm to 480 nm;
screen printing the composition as a layer over at least a part of a substrate, wherein the substrate and the light transmissive binder in a cured state have refractive indices that are within 0.02 of each other, and wherein the substrate is selected from the group consisting of: an acrylic, a polycarbonate, a silicone and a glass; and
at least partially curing the light transmissive binder.
2. The method of claim 1 , wherein the substrate comprises a thermoplastics material and further comprising heating the substrate to form a component of a selected shape.
3. The method of claim 1 , wherein the substrate is selected from the group consisting of: an acrylic, a polycarbonate, a silicone and a glass.
4. The method of claim 1 , and further comprising during screen printing, selectively varying a thickness of a deposition of the light transmissive binder such that after forming the photoluminescent wavelength conversion component into a selected shape, the light transmissive binder is of a substantially uniform thickness.
5. The method of claim 1 , wherein the light transmissive binder has in a cured state an elasticity of 300% to 500%.
6. The method of claim 1 , wherein the light transmissive binder has a viscosity 0.5 Pa·s to 5 Pa.·s or 1 Pa·s to 2.5 Pa·s.
7. The method of claim 1 , wherein the light transmissive binder is selected from the group consisting of: a polymer resin; a monomer resin; an acrylic, a silicone and a fluorinated polymer.
8. The method of claim 1 , wherein the light transmissive binder has in a cured state an elasticity in a range 300% to 500%.
9. The method of claim 1 , wherein the blue light excitable phosphor material is selected from the group consisting of: a silicate phosphor; an orthosilicate phosphor; a nitride phosphor; an oxy-nitride phosphor; a sulfate phosphor, an oxy-sulfate phosphor; and a garnet (YAG) phosphor.
10. The method of claim 1 , wherein the light reflective material is selected from the group consisting of: magnesium oxide, titanium dioxide, barium sulfate and combinations thereof.
11. The method of claim 1 , wherein the light reflective material has a particle size in a range of 0.1 μm to 1 μm.
12. The method of claim 11 , wherein a weight percent loading of the light reflective material to the blue light excitable phosphor material is in a range 0.01% to 10%.
13. The method of claim 1 , where the U.V. curable light transmissive binder is selected from the group consisting of: a polymer resin; a monomer resin, an acrylic, a silicone, and a fluorinated polymer.
14. The method of claim 1 , and comprising screen printing the U.V. curable photoluminescent ink over an entire light emitting surface of the substrate.
15. The method of claim 1 , and comprising screen printing the U.V. curable photoluminescent ink as a graduated pattern.
16. The method of claim 1 , and comprising screen printing the U.V. curable photoluminescent ink as a first order stochastic pattern comprising a pseudo random array of dots of substantially the same size.
17. The method of claim 1 , and comprising screen printing the U.V. curable photoluminescent ink as a second order stochastic pattern comprising a pseudo random array of dots of varying size.