Granted Patent B2

US 7,133,009 · App. 10/415,994 · Granted Nov 7, 2006

Abstract

Claims (35)

1. A multiplexed matrix alternating current (AC) electroluminescent display, comprising:

an array of matrix addressed capacitively switchable electroluminescent pixels, each capacitively switchable electroluminescent pixel including an electroluminescent pixel having an EL threshold voltage across said electroluminescent pixel and a circuit element connected in electrical series with said electroluminesent pixel, said circuit element being switchable at a first threshold voltage across said circuit element between an electrically insulating capacitive state and an electrically conducting state when a magnitude of an AC voltage applied across said capacitively switchable electroluminescent pixel is such that a voltage drop across said circuit element reaches said first threshold voltage, wherein each capacitively switchable electroluminescent pixel exhibits a first capacitance when the magnitude of the AC voltage applied across said capacitively switchable electroluminescent pixel is such that the voltage drop across said circuit element is less than said first threshold voltage and substantially no EL light emission occurs, and when the magnitude of the AC voltage applied across said capacitively switchable electroluminescent pixel is such that the voltage drop across said circuit element is larger than said first threshold voltage and a voltage drop across said electroluminescent pixel is smaller than the EL threshold voltage, said capacitively switchable electroluminescent pixel exhibits a second capacitance larger than said first capacitance but with substantially no EL light emission, and when the magnitude of the AC voltage applied across said capacitively switchable electroluminescent pixel is such that the voltage drop across said electroluminescent pixel is larger than said EL threshold voltage EL light emission occurs from said capacitively switchable electroluminescent pixel; and

power supply means connected to said array of matrix addressed capacitively switchable electroluminescent pixels for providing power to each capacitively switchable electroluminescent pixel.

2. The electroluminescent display according to claim 1 wherein said circuit element has a capacitance in said capacitive state that is substantially equal to, or less than, a capacitance of said electroluminescent pixel.

3. The electroluminescent display according to claim 1 wherein said circuit element has a capacitance in said capacitive state that is in a range of from about 1 to about 1,000,000 times less than a capacitance of said electroluminescent pixel.

4. The electroluminescent display according to claim 1 wherein said array of capacitively switchable electroluminescent pixels are arranged in rows and columns, and wherein each capacitively switchable electroluminescent pixel in a given row is connected to a row electrode, and wherein each capacitively switchable electroluminescent pixel in a given column is connected to a column electrode.

5. The electroluminescent display according to claim 4 wherein said circuit element is sandwiched between said electroluminescent pixel and one of said row and column electrodes.

6. The electroluminescent display according to claim 4 wherein a separate row voltage is applied to a specific row electrode, and a specific column voltage is applied to a specific column electrode, and wherein a difference of voltages applied to said row electrodes and said column electrodes is applied across the capacitively switchable electroluminescent pixel located at an intersection of said specific row and said specific column.

7. The electroluminescent display according to claim 6 wherein said circuit element is electrically insulating when the voltage across said capacitively switchable electroluminescent pixel is below a preselected threshold voltage, and wherein said preselected threshold voltage is selected to have a magnitude higher than a magnitude of a difference voltage applied to said capacitively switchable electroluminescent pixel located at the intersection of said specific row and said specific column when the lower of said row voltage and said column voltage is applied to said column electrode and said row electrode respectively.

8. The electroluminescent display according to claim 4 wherein said column electrode is formed on a surface of a substrate and an insulator layer is located on said column electrode, an electroluminescent phosphor layer being located on top of said insulator layer, and said circuit element being located on top of said electroluminescent phosphor layer, and said row electrode being located on top of said circuit element, and wherein either the row electrode and the circuit element or the substrate, the column electrode and the insulator layer are substantially transparent.

9. The electroluminescent display according to claim 4 wherein said column electrode is formed on a surface of a substrate and a an electroluminescent phosphor layer being located on top of said column electrode, and an insulator layer being located on top of said electroluminescent phosphor layer, and said circuit element being located on top of said insulator layer, and said row electrode being located top of said circuit element, and wherein either the row electrode, the circuit element and the insulator layer, or the substrate and the column electrode are substantially transparent.

10. The electroluminescent display according to claim 4 wherein said column electrode is formed on a surface of a substrate and a first insulator layer is located on said column electrode, an electroluminescent phosphor layer being located on top of said insulator layer and a second insulator layer being located on top of said electroluminescent phosphor layer, and said circuit element being located on top of said second insulator layer, and said row electrode being located on top of said circuit element, and wherein either the row electrode, the circuit element and the second insulator layer or the substrate, the column electrode and the first insulator layer are substantially transparent.

11. The electroluminescent display according to claim 8 wherein the row and column electrodes are interchanged.

12. The electroluminescent display according to claim 4 wherein said column electrode is formed on a surface of a substrate and said circuit element being located on top of said column electrode, an insulator layer is located on said circuit element, an electroluminescent phosphor layer being located on top of said insulator layer and said row electrode being located top of said electroluminescent phosphor layer, and wherein either the row electrode, or the substrate, the column electrode, the circuit element and the insulator layer are substantially transparent.

13. The electroluminescent display according to claim 4 wherein said column electrode is formed on a surface of a substrate and said circuit element being located on top of said column electrode, an electroluminescent phosphor layer being located on top of said circuit element and an insulator layer being located on top of said electroluminescent phosphor layer, and said row electrode being located top of said insulator layer, and wherein either the row electrode and the insulator layer or the substrate, the column electrode, and the circuit element are substantially transparent.

14. The electroluminescent display according to claim 4 wherein said column electrode is formed on a surface of a substrate and said circuit element being located on top of said column electrode, a first insulator layer is located on said circuit element, an electroluminescent phosphor layer being located on top of said first insulator layer and a second insulator layer being located on top of said electroluminescent phosphor layer, and said row electrode being located top of said second insulator layer, and wherein either the row electrode and the second insulator layer or the substrate, the column electrode, the circuit element and the first insulator layer are substantially transparent.

15. The electroluminescent display according to claim 12 wherein the row and column electrodes are interchanged.

16. The electroluminescent display according to claim 8 wherein said column electrode or said row electrode located on top of said substrate has a surface area substantially equal to a surface area of said electroluminescent phosphor layer and the other of said row electrode or said column electrode on said circuit element has a surface area substantially equal to said surface area of said electroluminescent phosphor layer.

17. The electroluminescent display according to claim 12 wherein said column electrode or said row electrode located on top of said substrate has a surface area substantially equal to a surface area of said electroluminescent phosphor layer and the other of said row electrode or said column electrode on said electroluminescent phosphor layer has a surface area substantially equal to said surface area of said electroluminescent phosphor layer.

18. The electroluminescent display according to claim 13 wherein said column electrode or said row electrode located on top of said substrate has a surface area substantially equal to a surface area of said electroluminescent phosphor layer and the other of said row electrode or said column electrode on said insulator layer has a surface area substantially equal to said surface area of said electroluminescent phosphor layer.

19. The electroluminescent display according to claim 14 wherein said column electrode or said row electrode located on top of said substrate has a surface area substantially equal to a surface area of said electroluminescent phosphor layer and the other of said row electrode or said column electrode on said second insulator layer has a surface area substantially equal to said surface area of said electroluminescent phosphor layer.

20. The electroluminescent display according to claim 9 wherein a conductive pad is located between said circuit element and said insulating layer.

21. The electroluminescent display according to claim 14 wherein a conductive pad is located between said circuit element and said first insulating layer.

22. The electroluminescent display according to claim 10 wherein a conductive pad is located between said circuit element and said second insulating layer.

23. The electroluminescent display according to claim 8 wherein a conductive pad is located between said circuit element and said electroluminescent phosphor layer.

24. The electroluminescent display according to claim 20 wherein the surface area of said row electrode or said column electrode adjacent to the circuit element is substantially lower than the surface area of said electroluminescent phosphor layer.

25. The electroluminescent display according to claim 1 wherein said circuit element is a layer of solid material having selected dielectric properties.

26. The electroluminescent display according to claim 25 wherein said layer of solid material is a dielectric material which functions as a capacitor when an electric field in a selected range of electric field strengths is applied across said layer and as a conductor when an electric field having an electric field strength outside of said selected range of electric field strengths is applied across said layer.

27. The electroluminescent display according to claim 26 wherein said dielectric material is selected from the group consisting of ZnS, SrS, Zn 2 Si x Ge (1−x) O 4 , Ga 2 O 3 , SrGa 2 O 4 and CaGa 2 O 4 .

28. The electroluminescent display according to claim 1 wherein said circuit element includes a fluid switching medium which is electrically insulating when a voltage below a threshold voltage is applied across said switching medium and electrically conducting when a voltage above said threshold is voltage applied across said switching medium.

29. The electroluminescent display according to claim 28 wherein said fluid switching medium is a gas.

30. The electroluminescent display according to claim 1 wherein said circuit element is a first circuit element, and wherein said electroluminescent display includes a second circuit element incorporated therein.

31. The electroluminescent display according to claim 1 wherein said circuit element has selected dimensions including length, width and thickness, a selected relative dielectric constant and breakdown potential to give a selected capacitance versus voltage characteristic.

32. The electroluminescent display according to claim 25 wherein said solid layer is sandwiched between insulating layers.

33. The electroluminescent display according to claim 28 wherein said fluid switching medium is sandwiched between insulating layers.

Assignments (10)