Display apparatus, method of driving display apparatus, electron emitter, method of driving electron emitter, apparatus for driving electron emitter, electron emission apparatus, and method of driving electron emission apparatus

• US 7,379,037 B2
• Filed: 03/24/2004
• Issued: 05/27/2008
• Est. Priority Date: 03/26/2003
• Status: Expired due to Fees

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Takeuchi, Yukihisa, Nanataki, Tsutomu, Akao, Takayoshi, Ohwada, Iwao
• Primary Examiner(s): Awad; Amr A.
• Assistant Examiner(s): Sherman; Stephen G
• Application Number:
  US10/808,258
• Publication Number:
  US 20040233136A1
• Time in Patent Office: 1,525 Days
• Field of Search: 345/75.2, 345/204, 345/690, 3151691-1694, 313495-496
• US Class Current: 345/75.2
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: H01J 1/312 having an electric field perpendicular to the surface, e.g. tunnel-effect cathodes of metal-insulator-metal [MIM] type H01J1/304- H01J1/308 take precedence
• CPC Class Codes: H01J 2201/3125 Metal-insulator-Metal [MIM] emission type cathodes
• CPC Class Codes: H01J 31/127 using large area or array sources, i.e. essentially a source for each pixel group

Abstract

One image is displayed in a period as one frame, which includes one charge accumulation period and one light emission period. In the charge accumulation period, all electron emitters are scanned, and voltages depending on the luminance levels of corresponding pixels are applied to the electron emitters which correspond to pixels to be turned on (to emit light), to accumulate charges (electrons) in amounts depending on the luminance levels of corresponding pixels in the electron emitters which correspond to pixels to be turned on. In the next light emission period, a constant voltage is applied to all the electron emitters to emit electrons in amounts depending on the luminance levels of corresponding pixels from the electron emitters which correspond to pixels to be turned on, thereby emitting light from the pixels to be turned on.

Claims

1. A display apparatus having a plurality of electron emitters arrayed in association with a plurality of pixels, for emitting electrons from the electron emitters to display an image, each electron emitter including a first electrode and a second electrode in direct contact with said electron emitter;

and

a drive circuit for scanning all the electron emitters to apply necessary voltages to the electron emitters, wherein;

necessary charges are accumulated in all the electron emitters in a first period;

a voltage required to emit electrons is applied to all the electron emitters to cause a plurality of electron emitters which correspond to pixels to emit light therefrom, for emitting light from said pixels, in a second period after said first period;

light is emitted from said pixels only during said second period; and

wherein one image is displayed in a period as one frame, said one frame including said first period and said second period;

wherein said drive circuit scans all said electron emitters and applies accumulation voltages depending on the luminance levels of corresponding pixels to the electron emitters which correspond to pixels to emit light therefrom in said first period, and applies a constant emission voltage to all the electron emitters in the second period after said first period;

wherein charges in amounts depending on the luminance levels of corresponding pixels are accumulated in the electron emitters which correspond to pixels to emit light therefrom in said first period; and

wherein electrons are emitted in amounts depending on the luminance levels of corresponding pixels from the electron emitters which correspond to pixels to emit light therefrom in said second period, thereby emitting light from the pixels.

2. A display apparatus according to claim 1, characterized in that

said drive circuit comprises:

a pulse generating circuit for generating a pulse signal having a constant pulse amplitude; and

an amplitude modulating circuit for amplitude-modulating said pulse signal to generate said accumulation voltage in said first period.

3. A display apparatus according to claim 1, characterized in that

said drive circuit comprises:

a pulse generating circuit for generating a pulse signal applicable to said electron emitters, said pulse signal having a voltage waveform including a positive-going edge or a negative-going edge which is continuously variable in level; and

a pulse width modulating circuit for pulse-width-modulating said pulse signal to generate said accumulation voltage in said first period.

4. A display apparatus according to claim 1, wherein said electron emitters have such characteristics that the electron emitters change to a first state in which electrons are accumulated when an electric field is applied in one direction to said electron emitters, and change from said first state to a second state in which electrons are emitted when an electric field is applied in another direction to said electron emitters, and a drive circuit is controlled to apply a voltage between a voltage for changing the electron emitters to said first state and a voltage for changing the electron emitters to a state immediately prior to said second state, to electron emitters which are unselected.

5. A display apparatus according to claim 1, characterized in that

said electron emitters are selected and unselected through corresponding select lines;

and

said drive circuit places the select lines of electron emitters which are unselected into a high impedance state.

6. A method of driving a display apparatus having a plurality of electron emitters arrayed in association with a plurality of pixels, for emitting electrons from the electron emitters to display an image, each electron emitter including a first electrode and a second electrode in direct contact with said electron emitter, said method comprising:

the step of accumulating necessary charges in all the electron emitters in a first period, which includes the step of scanning all said electron emitters, and applying accumulation voltages depending on the luminance levels of corresponding pixels to the electron emitters which correspond to pixels to emit light therefrom in said first period, to accumulate charges in amounts depending on the luminance levels of corresponding pixels in the electron emitters which correspond to pixels to emit light therefrom in said first period; and

the step of applying a voltage required to emit electrons to all the electron emitters to cause a plurality of electron emitters which correspond to pixels to emit light therefrom, for emitting light from said pixels, in a second period after said first period, which includes the step of applying a constant emission voltage to all the electron emitter'"'"'s in the second period after said first period, to emit electrons in amounts depending on the luminance levels of corresponding pixels from the electron emitters which correspond to pixels to emit light therefrom in said second period, thereby emitting light from the pixels;

wherein light is emitted from said pixels only during said second period and one image is displayed in a period as one flame, said one frame including said first period and said second period.

7. A method for driving a display apparatus according to claim 6, characterized in that

a pulse signal having a constant pulse amplitude is generated;

and

said pulse signal is amplitude-modulated to generate said accumulation voltage in said first period.

8. A method for driving a display apparatus according to claim 6, characterized in that

a pulse signal applicable to said electron emitters is generated, said pulse signal having a voltage waveform including a positive-going edge or a negative-going edge which is continuously variable in level;

and

said pulse signal is pulse-width-modulated to generate said accumulation voltage in said first period.

9. A method for driving a display apparatus according to claim 6, characterized in that

said electron emitters have such characteristics that the electron emitters change to a first state in which electrons are accumulated when an electric field is applied in one direction to said electron emitters, and change from said first state to a second state in which electrons are emitted when an electric field is applied in another direction to said electron emitters;

and

a voltage between a voltage for changing the electron emitters to said first state and a voltage for changing the electron emitters to a state immediately prior to said second state, is applied to electron emitters which are unselected.

10. A method of driving a display apparatus according to claim 6, characterized in that

said electron emitters are selected and unselected through corresponding select lines;

and

the select lines of electron emitters which are unselected are placed into a high impedance state.

11. An electron emission apparatus having a plurality of electron emitters, each electron emitter including a first electrode and a second electrode in direct contact with said electron emitter;

a pulse generating circuit for generating a pulse signal having a constant pulse amplitude; and

an amplitude modulating circuit for amplitude-modulating said pulse signal to generate an accumulation voltage in a first period.

wherein charges required for electron emission are accumulated in said plurality of electron emitters by applying accumulation voltages that depend on the amount of charges to be accumulated in said plurality of electron emitters in said first period; and

a constant emission voltage required for electron emission is applied to all the said plurality of electron emitters to emit electrons in an amount depending on the charges accumulated in said plurality of electron emitters in a second period after said first period; and

electrons are emitted from said plurality of electron emitters only during said second period.

12. An electron emission apparatus according to claim 11, characterized in that

said electron emitters have such characteristics that the electron emitters change to a first state in which electrons are accumulated when an electric field is applied in one direction to said electron emitters, and change from said first state to a second state in which electrons are emitted when an electric field is applied in another direction to said electron emitters;

said apparatus further comprising a drive circuit for applying a voltage between a voltage for changing the electron emitters to said first state and a voltage for changing the electron emitters to a state immediately prior to said second state, to electron emitters which are unselected.

13. An electron emission apparatus having a plurality of electron emitters, each electron emitter including a first electrode and a second electrode in direct contact with said electron emitter;

a pulse generating circuit for generating a pulse signal applicable to said electron emitters, said pulse signal having a voltage waveform including a positive-going edge or a negative-going edge which is continuously variable in level; and

a pulse width modulating circuit for pulse-width-modulating said pulse signal to generate an accumulation voltage in a first period,

wherein charges required for electron emission are accumulated in said plurality of electron emitters by applying accumulation voltages that depend on the luminance level selected for said plurality of electron emitters in said first period; and

a constant emission voltage required for electron emission is applied to said plurality of electron emitters to emit electrons in an amount depending on the charges accumulated in each of said plurality of electron emitters in a second period after said first period; and

electrons are emitted from said plurality of electron emitters only during said second period.

14. A method of driving an electron emission apparatus having a plurality of electron emitters each having a first electrode and a second electrode in direct contact with said electron emitter, said method comprising:

amplitude-modulating a pulse signal having a constant pulse amplitude to generate accumulation voltages in a first period;

accumulating charges required for electron emission in said plurality of electron emitters by applying the accumulation voltages that depend on the amount of charges to be accumulated in said plurality of electron emitters in said first period; and

applying a constant emission voltage required for electron emission to said plurality of electron emitters to emit electrons in an amount depending on the charges accumulated in said plurality of electron emitters in a second period after said first period,

wherein electrons are emitted from said plurality of electron emitters only during said second period.

15. A method of driving an electron emission apparatus according to claim 14, characterized in that

said electron emitters have such characteristics that the electron emitters change to a first state in which electrons are accumulated when an electric field is applied in one direction to said electron emitters, and change from said first state to a second state in which electrons are emitted when an electric field is applied in another direction to said electron emitters;

and

a voltage between a voltage for changing the electron emitters to said first state and a voltage for changing the electron emitters to a state immediately prior to said second state, is applied to electron emitters which are unselected.

16. A method of driving an electron emission apparatus having plurality of electron emitters, each electron emitter including a first electrode and a second electrode in direct contact with said electron emitter, said method comprising:

generating a pulse signal applicable to said electron emitters, said pulse signal having a voltage waveform including a positive-going edge or a negative-going edge which is continuously variable in level;

pulse-width modulating said pulse signal to generate accumulated voltages in said a first period;

accumulating charges required for electron emission in said plurality of electron emitters by applying the accumulation voltages that depend on the luminance level selected for said plurality of electron emitters in said first period; and

applying a constant emission voltage required for electron emission to said plurality of electron emitters to emit electrons in an amount depending on the charges accumulated in said electron emitters in a second period after said first period,

wherein electrons are emitted from said electron emitters only during said second period.