Light emitting device

• US 20050062390A1
• Filed: 08/25/2003
• Published: 03/24/2005
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Nanataki, Tsutomu, Takeuchi, Yukihisa, Ohwada, Iwao
• Granted Patent: US 7,067,970 B2
• Time in Patent Office: Days
• US Class Current: 313/310
• CPC Class Codes: H01J 1/304 Field-emissive cathodes
• CPC Class Codes: H01J 1/53 Electrodes intimately associated with a screen on or from which an image or pattern is formed, picked-up, converted, or stored
• CPC Class Codes: H01J 31/123 Flat display tubes

Abstract

A light emission device has an emitter made of a dielectric material, a cathode electrode disposed on a surface of the emitter, an anode electrode disposed on a reverse surface of the emitter, and a pulse generation source for applying a drive voltage between the cathode electrode and the anode electrode through a resistor. A fluorescent body is disposed on the surface of the emitter out of contact with the cathode, but as closely to the cathode electrode as possible.

Claims

1. A light emission device comprising:

a substance disposed in a vacuum atmosphere and serving as an emitter made of a dielectric material; and

a first electrode, a second electrode, and a fluorescent body which are disposed in contact with said substance serving as the emitter;

wherein when a drive voltage is applied between said first electrode and said second electrode, the polarization of at least a portion of said substance serving as the emitter is reversed or changed to emit electrons from at least a portion of said first electrode, and said electrons impinge upon said fluorescent body to emit light therefrom.

2. A light emission device according to claim 1, wherein said first electrode and said fluorescent body are disposed on a first surface of said substance serving as the emitter, and said second electrode is disposed on a second surface of said substance serving as the emitter.

3. A light emission device according to claim 2, wherein said first electrode and said fluorescent body have an outer peripheral edge and an inner peripheral edge, respectively, which face each other.

4. A light emission device according to claim 2, wherein said fluorescent body and said first electrode have an outer peripheral edge and an inner peripheral edge, respectively, which face each other.

5. A light emission device according to claim 2, wherein said first electrode and said second electrode have respective projected shapes as viewed in plan, and the projected shape of said second electrode has a protruding portion which protrudes from a peripheral edge of the projected shape of said first electrode.

6. A light emission device according to claim 5, wherein the projected shape of said first electrode and the projected shape of said second electrode are similar to each other.

7. A light emission device according to claim 5, wherein said protruding portion has a maximum length ranging from 1 μ

m to 500 μ

m.

8. A light emission device according to claim 1, wherein said first electrode and said second electrode are disposed in contact with a principal surface of said substance serving as the emitter, with a slit defined between said first electrode and said second electrode, said fluorescent body being disposed in at least said slit.

9. A light emission device according to claim 8, wherein said substance serving as the emitter has a portion exposed at least between said first electrode and said fluorescent body.

10. A light emission device according to claim 8, wherein said first electrode and said fluorescent body have an outer peripheral edge and an inner peripheral edge, respectively, which face each other.

11. A light emission device according to claim 10, wherein said fluorescent body and said second electrode have an outer peripheral edge and an inner peripheral edge, respectively, which face each other.

12. A light emission device according to claim 8, wherein said second electrode and said fluorescent body have an outer peripheral edge and an inner peripheral edge, respectively, which face each other.

13. A light emission device according to claim 12, wherein said fluorescent body and said first electrode have an outer peripheral edge and an inner peripheral edge, respectively, which face each other.

14. A light emission device according to claim 8, wherein said fluorescent body is disposed in covering relation to said second electrode.

15. A light emission device according to claims 1, wherein a step includes a preparatory period in which a first voltage making the potential of said first electrode higher than the potential of said second electrode is applied between said first electrode and said second electrode to polarize said substance serving as the emitter, and an electron emission period in which a second voltage making the potential of said first electrode lower than the potential of said second electrode is applied between said first electrode and said second electrode to reverse or change the polarization of said substance serving as the emitter to emit electrons therefrom, and said step is repeated.

16. A light emission device according to claim 8, wherein a step includes a preparatory period in which a first voltage making the potential of said first electrode higher than the potential of said second electrode is applied between said first electrode and said second electrode to polarize said substance serving as the emitter, and an electron emission period in which a second voltage making the potential of said first electrode lower than the potential of said second electrode is applied between said first electrode and said second electrode to reverse the polarization of said substance serving as the emitter to emit electrons from said first electrode, and a first cycle includes at least one said step, wherein a step includes a preparatory period in which said second voltage is applied between said first electrode and said second electrode to polarize said substance serving as the emitter, and an electron emission period in which said first voltage applied between said first electrode and said second electrode to reverse the polarization of said substance serving as the emitter to emit electrons from said second electrode, and a second cycle includes at least one said step, and wherein operation of said first cycle and operation of said second cycle are selectively performed.

17. A light emission device according to claim 15, wherein electrons are emitted from a portion of said first electrode in the vicinity of a triple point made up of said first electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step, and the emitted electrons impinge upon said fluorescent body to emit light therefrom.

18. A light emission device according to claim 15, wherein electrons are emitted from a portion of said first electrode in the vicinity of a triple point made up of said first electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step, and the emitted electrons are reflected by a surface of said substance serving as the emitter and impinge upon said fluorescent body to emit light therefrom.

19. A light emission device according to claim 15, wherein electrons are emitted from a portion of said first electrode in the vicinity of a triple point made up of said first electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step, the emitted electrons impinge upon said substance serving as the emitter to emit secondary electrons therefrom, and said secondary electrons impinge upon said fluorescent body to emit light therefrom.

20. A light emission device according to claim 16, wherein electrons are emitted from a portion of said first electrode in the vicinity of a triple point made up of said first electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step of said first cycle, and the emitted electrons impinge upon said fluorescent body to emit light therefrom, and wherein electrons are emitted from a portion of said second electrode in the vicinity of a triple point made up of said second electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step of said second cycle, and the emitted electrons impinge upon said fluorescent body to emit light therefrom.

21. A light emission device according to claim 16, wherein electrons are emitted from a portion of said first electrode in the vicinity of a triple point made up of said first electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step of said first cycle, and the emitted electrons are reflected by a surface of said substance serving as the emitter and impinge upon said fluorescent body to emit light therefrom, and wherein electrons are emitted from a portion of said second electrode in the vicinity of a triple point made up of said second electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step of said second cycle, and the emitted electrons are reflected by a surface of said substance serving as the emitter and impinge upon said fluorescent body to emit light therefrom.

22. A light emission device according to claim 16, wherein electrons are emitted from a portion of said first electrode in the vicinity of a triple point made up of said first electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step of said first cycle, the emitted electrons impinge upon a surface of said substance serving as the emitter to emit secondary electrons therefrom, and said secondary electrons impinge upon said fluorescent body to emit light therefrom, and wherein electrons are emitted from a portion of said second electrode in the vicinity of a triple point made up of said second electrode, said substance serving as the emitter, and a vacuum atmosphere during said electron emission period in said step of said second cycle, the emitted electrons impinge upon said substance serving as the emitter to emit secondary electrons therefrom, and said secondary electrons impinge upon said fluorescent body to emit light therefrom.

23. A light emission device according to claim 1, wherein said vacuum atmosphere has a vacuum level of at most 2000 Pa.

24. A light emission device according to claim 23, wherein said vacuum atmosphere has a vacuum level of at most 10⁻

3 Pa.

25. A light emission device according to claim 1, wherein said substance serving as the emitter is made of a piezoelectric material, an anti-ferroelectric material, or an electrostrictive material.