Phosphors

• US 4,365,184 A
• Filed: 03/10/1980
• Issued: 12/21/1982
• Est. Priority Date: 06/01/1976
• Status: Expired due to Term

• Current Assignee: The secretary of state for defence in her Britannic Majesty's Government of the United Kingdom of Great Britain And Northern Ireland
• Original Assignee: The secretary of state for defence in her Britannic Majesty's Government of the United Kingdom of Great Britain And Northern Ireland
• Inventors: Vecht, Aron, Higton, Malcolm
• Primary Examiner(s): Smith, John D.
• Application Number:
  US06/128,552
• Time in Patent Office: 1,016 Days
• Field of Search: 252/301.4 S, 252/301.6 S, 427/64, 427/66, 427/12, 427/157, 29/25.11, 29/25.13, 313/503, 313/506, 313/509
• US Class Current: 313/503
• CPC Class Codes: C09K 11/586 with alkaline earth metals
• CPC Class Codes: C09K 11/7703 with alkaline earth metals
• CPC Class Codes: C09K 11/7718 with alkaline earth metals
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source

Abstract

This invention provides phosphors for use in electroluminescent devices. Each phosphor contains a dopant and at least one of the sulphides of the group consisting of strontium, calcium, barium and magnesium sulphide.

Claims

1. A process for making a DC electroluminescent device including the steps of

a. producing phosphor particles including a sulphide selected from the group consisting of strontium, calcium, barium and magnesium sulphide mixed with a dopant comprising cerium,

b. coating said phosphor particles with an element of group Ib of the Periodic Table to introduce said element into the extended surface of said particles,

c. embedding the coated particles in a matrix,

d. arranging the resulting particle bearing matrix as a phosphor layer in contact with two electrodes, and

e. passing a forming direct electrical current between the two electrodes until the electrical resistance is increased in a localized and predetermined region of the phosphor layer.

2. A process for making a DC electroluminescent device including the steps of

a. producing phosphor particles comprising (1) stronium sulfide mixed with a dopant containing cerium, (2) strontium sulfide mixed with a dopant containing copper, (3) strontium sulfide mixed with a dopant containing copper and sodium or (4) calcium sulfide mixed with a dopant containing cerium,

b. coating said phosphor particles with an element of group Ib of the Periodic Table to introduce said element into the extended surface of said particles,

c. embedding the coated particles in a matrix,

d. arranging the resulting particle bearing matrix as a phosphor layer in contact with two electrodes, and

e. passing a forming direct electrical current between the two electrodes until the electrical resistance is increased in a localized and predetermined region of the phosphor layer.

3. The process of claim 2 wherein the phosphor particles, contain strontium sulfide and a dopant containing copper and sodium.

4. The process of claim 2 wherein the phosphor particles comprise strontium sulfide mixed with a dopant comprising cerium.

5. The process of claim 2 wherein the phosphor particles comprise strontium sulfide mixed with a dopant containing copper.

6. The process of claim 2 wherein the phosphor particles comprise calcium sulfide mixed with a dopant containing cerium.

7. The product of the process of claim 4, 5 or 6.

8. A DC electroluminescent device comprising an electrical insulating base, a first electrode supported on the base, a plastic matrix having phosphor particles embedded therein disposed as a layer with one side on said base and over said first electrode and an opposite side, a second electrode disposed in electrical contact with said opposite side of the said layer, and means for connecting said electrodes to a souce of DC electric current to excite the phosphor layer to emit light, said phosphor particles comprising a member selected from the group consisting of strontium sulphide, calcium sulphide, barium sulphide, and magnesium sulphide mixed with a dopant comprising cerium which activates the phosphor to be electroluminescent, said phosphor particles being coated with an element of Group Ib of the Periodic Table.

9. A DC electroluminescent device comprising an electrical insulating base, a first electrode supported on the base, a plastic matrix having phosphor particles embedded therein disposed as a layer with one side on said base and over said first electrode and an opposite side, a second electrode disposed in electrical contact with said opposite side of the said layer, and means for connecting said electrodes to a source of DC electric current to excite the phosphor layer to emit light, said phosphor particles comprising (1) strontium sulfide mixed with a dopant containing cerium, (2) strontium sulfide mixed with a dopant containing copper, (3) strontium sulfide mixed with a dopant containing copper and sodium, or (4) calcium sulfide mixed with a dopant containing cerium which dopant activates the phosphor to be electroluminescent, said phosphor particles being coated with an element of Group Ib of the Periodic Table.

10. The electroluminescent device of claim 9 wherein the phosphor particles contain strontium sulphide and a dopant comprising both copper and sodium.

11. The electroluminescent device of claim 9 wherein the phosphor particles comprise strontium sulfide mixed with a dopant containing cerium.

12. The electroluminescent device of claim 9 wherein the phosphor particles comprise strontium sulfide mixed with a dopant containing copper.

13. The electroluminescent device of claim 9 wherein the phosphor particles comprise calcium sulfide mixed with a dopant containing cerium.