Electron emitting method of electron emitter

• US 20040104689A1
• Filed: 06/11/2003
• Published: 06/03/2004
• Est. Priority Date: 11/29/2002
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Nanataki, Tsutomu, Takeuchi, Yukihisa, Ohwada, Iwao
• Granted Patent: US 7,129,642 B2
• Time in Patent Office: Days
• US Class Current: 315/169.4
• CPC Class Codes: H01J 1/30 Cold cathodes, e.g. field-emissive cathode
• CPC Class Codes: H01J 1/32 Secondary-electron-emitting electrodes H01J1/35 takes precedence

Abstract

An electron emitter has an emitter section formed on a substrate, and a cathode electrode and an anode electrode formed on a same surface of the emitter section. A slit is formed between the cathode electrode and the anode electrode. A drive voltage from a pulse generation source is applied between the cathode electrode and the anode electrode, and the anode electrode is connected to the ground. A collector electrode is provided above the emitter section at a position facing the slit. The collector electrode is connected to a bias voltage source through a resistor. The emitter section is made of a piezoelectric material.

Claims

1. A method of emitting electrons from an electron emitter including an emitter section made of a dielectric material, a first electrode in contact with said emitter section, and a second electrode in contact with said emitter section, said method comprising the steps of:

polarizing said emitter section in one direction; and

applying an electric field beyond a coercive field to said emitter section through said first and second electrodes to reverse polarization of said emitter section for emitting electrons.

2. A method of emitting electrons according to claim 1, wherein said emitter section is made of a piezoelectric material.

3. A method of emitting electrons according to claim 2, wherein said electric field beyond said coercive field is applied to said emitter section within a certain period for emitting electrons.

4. A method of emitting electrons according to claim 2, wherein said polarization of said emitter section in one direction is performed by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period, and

said polarization reversal of said emitter section for emitting electrons is performed by applying a second voltage between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period.

5. A method of emitting electrons according to claim 4, wherein a level of said second voltage is controlled so that said electric field beyond said coercive field is applied to said emitter section within a certain period from the beginning of said second period.

6. A method of emitting electrons according to claim 1, wherein said emitter section is made of an anti-ferroelectric material.

7. A method of emitting electrons according to claim 6, wherein said electric field applied to said emitter section has a level for inducing phase transition of said emitter section into a ferroelectric material within a certain period, and changing polarization of said emitter section for emitting electrons.

8. A method of emitting electrons according to claim 6, wherein said polarization of said emitter section in one direction is performed by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period, and

phase transition of said emitter section into a ferroelectric material is induced, and polarization of said emitter section is changed by applying a second voltage between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period.

9. A method of emitting electrons according to claim 8, wherein said first voltage applied between said first electrode and said second electrode in said first period is 0V, and polarization of said emitter section is reset.

10. A method of emitting electrons according to claim 8, wherein a level of said second voltage is controlled so that phase transition of said emitter section into a ferroelectric material is induced within a certain period from the beginning of said second period, and an electric field is applied to said emitter section to change polarization of said emitter section for emitting electrons.

11. A method of emitting electrons according to claim 8, wherein a level of said second voltage is controlled at the beginning of said second period to repeat a series of cycle in which said second voltage reaches a level required for electron emission and the voltage between said first electrode and said second electrode drops due to electron emission to a threshold level for resetting polarization of said emitter section.

12. A method of emitting electrons according to claim 1, wherein said emitter section is made of an electrostrictive material.

13. A method of emitting electrons according to claim 12, wherein said polarization of said emitter section in one direction is performed by applying a first voltage between said first electrode and said second electrode for causing said first electrode to have a potential higher than a potential of said second electrode in a first period, and

polarization of said emitter section is changed for emitting electrons by applying a second voltage between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode in a second period.

14. A method of emitting electrons according to claim 13, wherein said first voltage applied between said first electrode and said second electrode in said first period is 0V, and polarization of said emitter section is reset.

15. A method of emitting electrons according to claim 13, wherein a level of said second voltage is controlled so that an amount of polarization in the emitter section within a certain period from the beginning of said second period is controlled, and the number of emitted electrons is controlled.

16. A method of emitting electrons according to claim 13, wherein a level of said second voltage applied at the beginning of said second period is controlled so that electron emission continues by slight fluctuation of the voltage between said first electrode and said second electrode.

17. A method of emitting electrons according to claim 1, wherein

said first electrode is formed in contact with said emitter section;

said second electrode is formed in contact with said emitter section; and

a slit is formed between said first electrode and said second electrode.

18. A method of emitting electrons according to claim 17, wherein polarization reversal or polarization change occurs in an electric field E applied to said emitter section represented by E=Vak/d, where d is a width of said slit, and Vak is a voltage between said first electrode and said second electrode.

19. A method of emitting electrons according to claim 18, wherein said voltage Vak is less than a dielectric breakdown voltage of said emitter section.

20. A method of emitting electrons according to claim 1, wherein said first electrode is formed on a first surface of said emitter section, and said second electrode is formed on a second surface of said emitter section.

21. A method of emitting electrons according to claim 20, wherein polarization reversal or polarization change occurs in an electric field E applied to said emitter section represented by E=Vak/h, where h is a thickness of said emitter section between said first electrode and said second electrode, and Vak is a voltage between said first electrode and said second electrode.

22. A method of emitting electrons according to claim 21, wherein said voltage Vak is less than a dielectric breakdown voltage of said emitter section.

23. A method of emitting electrons according to claim 1, wherein said electric field is applied between said first electrode and said second electrode for causing said first electrode to have a potential lower than a potential of said second electrode to reverse or change polarization of at least a portion of said emitter section;

and

the polarization reversal or polarization change induces emission of electrons in the vicinity of said first electrode.

24. A method of emitting electrons according to claim 1, wherein said electric field is applied between said first electrode and said second electrode to reverse or change polarization of at least a portion of said emitter section;

the polarization reversal or polarization change causes positive poles of dipole moments in the vicinity of said first electrode to be oriented toward said first electrode, inducing emission of primary electrons from said first electrode; and

said emitted primary electrons impinge upon said emitter section to induce emission of secondary electrons from said emitter section.

25. A method of emitting electrons according to claim 24, wherein said first electrode, said emitter section, and a vacuum atmosphere define a triple point;

and

primary electrons are emitted from a portion of said first electrode in the vicinity of said triple point, and said emitted primary electrons impinge upon said emitter section to induce emission of secondary electrons from said emitter section.