Electroluminescent phosphor with plural moisture resistant coatings thereon

Abstract

A moisture-resistant electroluminescent phosphor is provided wherein the individual phosphor particles have a first coating of an inorganic moisture-resistant coating and a second coating of an organic moisture-resistant coating. The process for making the moisture-resistant phosphor comprises applying a first layer of an inorganic moisture-resistant coating to individual particles of an electroluminescent phosphor to form a first-coated phosphor, substantially isolating said first-coated phosphor from contact with atmospheric oxygen and moisture, and applying a second layer of an organic moisture-resistant coating to the first-coated phosphor to form a second-coated phosphor.

1 . A process for providing a moisture-resistant electroluminescent phosphor comprising the steps of: 
 applying a first layer of an inorganic moisture-resistant coating to individual particles of a phosphor to form a first-coated phosphor,    substantially isolating said first-coated phosphor from contact with atmospheric oxygen and moisture; and    applying a second layer of an organic moisture-resistant coating to form a second-coated phosphor.    
     
     
         2 . The process of  claim 1  wherein said first layer is an aluminum nitride.  
     
     
         3 . The process of  claim 1  wherein said electroluminescent phosphor comprises zinc sulfide activated with one or more activators.  
     
     
         4 . The process of  claim 1  wherein said organic coating is substantially transmissive of visible light, electrically insulating, and has low moisture permeability.  
     
     
         5 . The process of  claim 1  wherein the second layer is a parylene, polyester, polyalkylacrylate, or vinyl-epoxy resin.  
     
     
         6 . The process of  claim 5  wherein the first layer is an aluminum nitride.  
     
     
         7 . The process of  claim 2  wherein the second layer is a parylene.  
     
     
         8 . The process of  claim 2  wherein the second layer is poly(p-xylylene) or poly(p-α-xylylene) with α=H, Cl, Br, F, alkyl or amino.  
     
     
         9 - 16 . (canceled).