Electroluminescent phosphor particles encapsulated with an aluminum oxide based multiple oxide coating
AssigneeMinnesota Mining and Manufacturing Company
InventorKenton D. Budd
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Abstract
Encapsulated electroluminescent phosphor particles and a method of making same. Each phosphor particle is encapsulated by a substantially transparent aluminum oxide-based multiple oxide coating. The encapsulated phosphors exhibit high initial luminescent brightness and high resistance to humidity-accelerated decay of luminescent brightness. The aluminum oxide-based coating provides reduced sensitivity to chemical degradation caused by exposure to condensed moisture or otherwise liquid water. The coating comprises the aluminum oxide and at least one other metal oxide.
Claims26
A plurality of encapsulated particles, each of said encapsulated particles comprising:
- a phosphor particle of an electroluminescent phosphor material which exhibits humidity-accelerated decay in the presence of moisture;
- and
- a substantially transparent multiple metal oxide coating which is more resistant to chemical degradation from liquid water than an aluminum oxide coating and which sufficiently encapsulates said phosphor particle to provide said phosphor particle with substantial protection from humidity-accelerated decay, said coating comprising said aluminum oxide and at least one other metal oxide which are not in the form of the compound mullite.
A plurality of encapsulated particles, each of said encapsulated particles comprising:
- a phosphor particle of an electroluminescent phosphor material which exhibits humidity-accelerated decay in the presence of moisture;
- and
- a substantially transparent multiple metal oxide coating which is more resistant to chemical degradation from liquid water than an aluminum oxide coating and which sufficiently encapsulates said phosphor particle to provide said phosphor particle with substantial protection from humidity-accelerated decay, said coating comprising said aluminum oxide, a silicon oxide and at least one other metal oxide.
A method of encapsulating phosphor particles comprising the steps of:
- providing a bed of phosphor particles, each of which exhibits humidity-accelerated decay in the presence of moisture;
- providing at least two precursors comprising a vapor phase aluminum oxide precursor and at least one other vapor phase metal oxide precursor;
- and
- exposing the bed to the precursors such that the precursors chemically react and encapsulate each phosphor particle with a multiple metal oxide coating that comprises an aluminum oxide and at least one other metal oxide,
- wherein the aluminum oxide and the at least one other metal oxide are not in the form of the compound mullite, and the coating is substantially transparent, more resistant to chemical degradation from liquid water than a coating consisting essentially of aluminum oxide, and sufficiently encapsulating to provide the phosphor particle with substantial protection from humidity-accelerated decay.
A method of encapsulating phosphor particles comprising the steps of:
- providing a bed of phosphor particles, each of which exhibits humidity-accelerated decay in the presence of moisture;
- providing at least three precursors comprising a vapor phase aluminum oxide precursor, a vapor phase silicon oxide precursor and at least one other vapor phase metal oxide precursor;
- and
- exposing the bed to the precursors such that the precursors chemically react and encapsulate each phosphor particle with a multiple metal oxide coating that comprises an aluminum oxide, a silicon oxide and at least one other metal oxide,
- wherein the coating is substantially transparent, more resistant to chemical degradation from liquid water than a similar coating consisting essentially of aluminum oxide, and sufficiently encapsulating to provide the phosphor particle with substantial protection from humidity-accelerated decay.
Dependencies are inferred from the claim text.