Diode structure flat panel display

• US 5,612,712 A
• Filed: 06/07/1995
• Issued: 03/18/1997
• Est. Priority Date: 03/16/1992
• Status: Expired due to Term

• Current Assignee: Applied Nanotech Holdings Incorporated (Nano Magic, Inc.)
• Original Assignee: Microelectronics and Computer Technology Corporation
• Inventors: Kumar, Nalin, Xie, Chenggang
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US08/479,270
• Time in Patent Office: 650 Days
• Field of Search: 345/63, 345/74, 345/75, 345/77, 345/89, 345/147, 345/148, 313/495
• US Class Current: 345/75.2
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: H01J 1/304 Field-emissive cathodes
• CPC Class Codes: H01J 1/3042 microengineered, e.g. Spindt-type
• CPC Class Codes: H01J 2201/304 Field emission cathodes
• CPC Class Codes: H01J 2201/30426 Coatings on the emitter surface, e.g. with low work function materials
• CPC Class Codes: H01J 2201/30457 Diamond
• CPC Class Codes: H01J 2201/319 Circuit elements associated with the emitters by direct integration
• CPC Class Codes: H01J 2329/8625 Spacing members
• CPC Class Codes: H01J 2329/864 characterised by the material
• CPC Class Codes: H01J 29/085 Anode plates, e.g. for screens of flat panel displays
• CPC Class Codes: H01J 31/127 using large area or array sources, i.e. essentially a source for each pixel group
• CPC Class Codes: H01J 61/0677 characterised by the electron emissive material
• CPC Class Codes: H01J 63/06 Lamps with luminescent screen excited by the ray or stream
• CPC Class Codes: H01J 9/027 of thin film cathodes

Abstract

A matrix-addressed diode flat panel display of field emission type is described, utilizing a diode (two terminal) pixel structure. The flat panel display comprises a cathode assembly having a plurality of cathodes, each cathode including a layer of cathode conductive material and a layer of a low effective work-function material deposited over the cathode conductive material and an anode assembly having a plurality of anodes, each anode including a layer of anode conductive material and a layer of cathodoluminescent material deposited over the anode conductive material, the anode assembly located proximate the cathode assembly to thereby receive charged particle emissions from the cathode assembly, the cathodoluminescent material emitting light in response to the charged particle emissions. The flat panel display further comprises means for selectively varying field emission between the plurality of corresponding light-emitting anodes and field-emission cathodes to thereby effect an addressable grey-scale operation of the flat panel display.

Claims

1. A diode flat panel display consisting of only anode and cathode electrodes, comprising:

a plurality of corresponding light-emitting anodes and field-emission cathodes, each of said anodes emitting light in response to emission from each of said corresponding cathodes; and

means for addressing and electrically exciting selectable ones of said corresponding anodes and cathodes by changing an electrical potential of both said corresponding cathode and anode.

2. The display as recited in claim 1 wherein said cathodes are divided into cathode subdivisions.

3. The display as recited in claim 1 wherein said anodes are divided into anode subdivisions.

4. The display as recited in claim 2 wherein each cathode subdivision is independently addressable.

5. The display as recited in claim 3 wherein each anode subdivision is independently addressable.

6. The display as recited in claim 4 wherein said cathode subdivisions are addressable in various combinations to allow a grey scale operation of said cathodes.

7. The display as recited in claim 5 wherein said anode subdivisions are addressable in various combinations to allow a grey scale operation of said anodes.

8. The display as recited in claim 6 wherein said cathode subdivisions are of various sizes.

9. The display as recited in claim 7 wherein said anode subdivisions are of various sizes.

10. The display as recited in claim 8 wherein said sizes of said cathode subdivisions are related to one another by powers of 2.

11. The display as recited in claim 9 wherein said sizes of said anode subdivisions are related to one another by powers of 2.

12. The display as recited in claim 1 wherein said plurality of anodes comprise phosphor strips.

13. The display as recited in claim 1 wherein each of said cathodes comprises:

a substrate;

an electrically resistive layer deposited over said substrate; and

a layer of material having a low effective work function deposited over said resistive layer.

14. The display as recited in claim 1 wherein an electrical potential provided by a diode biasing circuit is continuously applied to said corresponding anodes and cathodes.

15. The display as recited in claim 14 wherein said corresponding cathode and anode pair is electrically activated in response to application of a total electrical potential equal to a sum of said electrical potential provided by said diode biasing circuit and an electrical potential provided by a driver circuit.

16. The display as recited in claim 15 wherein said electrical potential provided by said driver circuit is substantially less than said electrical potential provided by said diode biasing circuit.

46. The display as recited in claim 1 wherein each of said cathodes comprises:

two conductive layers having different resistivities, wherein a lower one of said two conductive layers has a higher conductivity than an upper one of said two conductive layers.

17. A method of operation of a diode flat panel display consisting of only anode and cathode electrodes, comprising the steps of:

providing a plurality of corresponding light-emitting anodes and field-emission cathodes, each of said anodes emitting light in response to emission from each of said corresponding cathodes; and

addressing and electrically exciting selectable ones of said corresponding anodes and cathodes by changing an electrical potential of both said corresponding cathode and anode.

18. The method as recited in claim 17 wherein said cathodes are divided into cathode subdivisions.

19. The method as recited in claim 17 wherein said anodes are divided into anode subdivisions.

20. The method as recited in claim 18 wherein each cathode subdivision is independently addressable.

21. The method as recited in claim 19 wherein each anode subdivision is independently addressable.

22. The method as recited in claim 20 wherein said cathode subdivisions are addressable in various combinations to allow a grey scale operation of said cathodes.

23. The method as recited in claim 21 wherein said anode subdivisions are addressable in various combinations to allow a grey scale operation of said anodes.

24. The method as recited in claim 22 wherein said cathode subdivisions are of various sizes.

25. The method as recited in claim 23 wherein said anode subdivisions are of various sizes.

26. The method as recited in claim 24 wherein said sizes of said cathode subdivisions are related to one another by powers of 2.

27. The method as recited in claim 25 wherein said sizes of said anode subdivisions are related to one another by powers of 2.

28. The method as recited in claim 17 wherein said plurality of anodes comprise phosphor strips.

29. The method as recited in claim 17 wherein each of said cathodes comprises:

a substrate;

an electronically resistive layer deposited over said substrate; and

a layer of material having a low effective work function deposited over said resistive layer.

30. The method as recited in claim 17 wherein an electrical potential provided by a diode biasing circuit is continuously applied to said corresponding anodes and cathodes.

31. The method as recited in claim 30 wherein said corresponding cathode and anode pair is electrically activated in response to application of a total electrical potential equal to a sum of said electrical potential provided by said diode biasing circuit and an electrical potential provided by a driver circuit.

32. The method as recited in claim 31 wherein said electrical potential provided by said driver circuit is substantially less than said electrical potential provided by said diode biasing circuit.

33. A system for implementing a grey scale in a diode flat panel display consisting of only anode and cathode electrodes, said system comprising:

a plurality of field emission cathodes arranged in rows;

a plurality of light emitting anodes arranged in columns, each column subdivided into sub-columns, said anodes responsive to electrons emitted from said cathodes;

means for joining said rows of cathodes and said columns of anodes to form a pattern of pixels; and

means for independently and simultaneously addressing a cathode row and a combination of anode subcolumns within an anode column to thereby produce various levels of pixel intensity.

34. The system as recited in claim 33 wherein said subcolumns are of varying widths.

35. The system as recited in claim 33 wherein said anode comprises a phosphor.

36. The system as recited in claim 33 wherein said field emission cathode comprises:

a substrate;

an electronically resistive layer deposited over said substrate; and

a layer of material having a low effective work function deposited over said resistive layer.

37. The system as recited in claim 36 wherein said material has a low effective work function.

38. The system as recited in claim 33 wherein said rows of cathodes and said columns of anodes are separated by a physical gap and an electrical potential provided by a diode biasing circuit.

39. The system as recited in claim 38 wherein said subcolumns of anodes are activated by said rows of cathodes in response to a total electrical potential equal to a sum of said electrical potential provided by said diode biasing circuit and an electrical potential provided by a driver circuit.

40. The system as recited in claim 39 wherein said electrical potential provided by said driver circuit is substantially less than said electrical potential provided by said diode biasing circuit.

41. The system as recited in claim 33 wherein said various levels of intensity are discrete levels.

42. A diode flat panel display consisting of only anode and cathode electrodes, comprising:

a plurality of corresponding light-emitting anodes and field-emission cathodes, each of said anodes emitting light in response to emission from each of said corresponding cathodes; and

means for selectively varying field emission between said plurality of corresponding light-emitting anodes and field-emission cathodes to thereby effect an addressable grey-scale operation of said flat panel display.

43. The display as recited in claim 42 wherein emission between said plurality of corresponding light-emitting anodes and field-emission cathodes is varied by application of a variable electrical potential between selectable ones of said plurality of corresponding light-emitting anodes and field-emission cathodes.

44. The display as recited in claim 42 wherein emission between said plurality of corresponding light-emitting anodes and field-emission cathodes is varied by applying a switched constant electrical potential between selectable ones of said plurality of corresponding light-emitting anodes and field-emission cathodes.

45. The display as recited in claim 44 wherein said constant electrical potential is pulse width modulated.

47. A diode flat panel display consisting of only anode and cathode electrodes, comprising:

a plurality of corresponding light-emitting anodes and field emission cathodes, each of said anodes emitting light in response to emission from each of said corresponding cathodes, wherein each of said cathodes comprises;

a substrate;

an electrically resistive layer deposited over said substrate; and

a conductive material deposited over said resistive layer.