Solid-state light emitting devices and signage with photoluminescence wavelength conversion and photoluminescent compositions therefor

Abstract

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.

What is claimed is: 
     
         1 . A method of depositing a photoluminescent material as a substantially uniform layer on a substrate, comprising:
 screen printing a photoluminescent ink as a substantially uniform layer onto a substrate, wherein the photoluminescent ink comprises a mixture of a blue light excitable phosphor material and a light transmissive binder, the blue light excitable phosphor being excitable by light of wavelength 380 nm to 480 nm, and the weight loading of the blue light excitable phosphor material to the light transmissive binder material is in a range of 40% to 75%; and   at least partially curing the light transmissive binder.   
     
     
         2 . The method of  claim 1 , comprising making multiple screen printing passes. 
     
     
         3 . The method of  claim 1 , comprising repeating multiple times the steps of screen printing the layer of the photoluminescent ink and at least partially curing the light transmissive binder. 
     
     
         4 . 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. 
     
     
         5 . The method of  claim 4 , and further comprising during screen printing, selectively varying a thickness of a deposition of the photoluminescent ink such that after forming the component into the selected shape, the layer of photoluminescent is of a substantially uniform thickness. 
     
     
         6 . The method of  claim 1 , wherein the light transmissive binder has in a cured state an elasticity of 300% to 500%. 
     
     
         7 . The method of  claim 1 , wherein the photoluminescent ink has a viscosity of 0.5 Pa·s to 5 Pa·s, 
     
     
         8 . The method of  claim 1 , wherein the light transmissive binder has a viscosity of 1 Pa·s to 2.5 Pa·s. 
     
     
         9 . The method of  claim 1 , wherein the light transmissive binder is U.V. curable. 
     
     
         10 . The method of  claim 1 , wherein the blue light excitable phosphor material has an average particle size of 10 μm to 20 μm. 
     
     
         11 . 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. 
     
     
         12 . The method of  claim 1 , wherein particles of a light reflective material are suspended in the light transmissive binder. 
     
     
         13 . The method of  claim 12 , wherein the light reflective material is selected from the group consisting of: magnesium oxide, titanium dioxide, barium sulfate and combinations thereof. 
     
     
         14 . The method of  claim 13 , wherein the light reflective material has a particle size in a range of 0.1 μm to 10 μm. 
     
     
         15 . The method of  claim 12 , wherein a weight percent loading of light reflective material to phosphor material is in a range 0.01% to 10%. 
     
     
         16 . The method of  claim 1 , wherein the substrate and light transmissive binder in a cured state have refractive indices that are within 0.02 of each other. 
     
     
         17 . The method of  claim 1 , wherein the substrate comprises a light transmissive surface and the photoluminescent ink is provided on at least a part of the light transmissive surface. 
     
     
         18 . The method of  claim 17 , wherein the substrate is selected from the group consisting of: an acrylic, a polycarbonate, a silicone and a glass. 
     
     
         19 . The method of  claim 1 , wherein the substrate comprises a light reflective surface. 
     
     
         20 . The method of  claim 19 , wherein the light reflective surface is selected from the group consisting of: silver, aluminum, chromium, a light reflective polymer, a light reflective paper, a light reflective paint and a light reflective metal.