KR20050059541A - Field emission device and field emission display - Google Patents

Abstract

Disclosed is a field emission device. The disclosed device comprises: a plurality of cathode electrodes formed in a stripe shape in one direction on a substrate and arranged with a plurality of unit CNT emitters thereon, and through holes through which electrons emitted from the unit CNT emitters pass; A gate electrode having a gate insulating layer having a gate insulating layer, a gate hole defining a passage of the electrons on the gate insulating layer, and a focus gate electrode which focuses an electron beam at a predetermined distance upwardly from the gate electrode, wherein the focus gate is provided. The electrode has first and second electrodes formed to face each other in a vertical direction with respect to the cathode electrode at both ends of the cathode electrode, and the side facing each other in the first and second electrode with each other with the cathode electrode therebetween Characterized in that the comb electrode is formed extending in parallel in the opposite direction .

Description

Field emission device and field emission display device {Field emission device and field emission display}

The present invention relates to a field emission device, and more particularly, to a field emission device and a field emission display device using a carbon nanotube (CNT).

Carbon nanotubes (CNTs) are materials that have a very low voltage due to their small diameter and the sharpness of the tube ends. They have similar properties to C60 (fulleren), but have excellent electron emission characteristics, chemical and mechanical durability in the form of tubes. And the physical properties and applicability has been studied. Spindt-type field emission devices currently used for field emission displays utilize micro tips as emitters in which electrons are emitted. Such a micro tip has a problem in that its life is shortened due to the influence of an atmosphere gas and a non-uniform electric field during field emission. In addition, in order to lower the driving voltage for electric field emission, the work function must be lowered, but there is a limitation as a conventional metal micro tip. As a material for overcoming this problem, an electric field emission array using carbon nanotubes having excellent durability and excellent electron conductivity as an electron emission source has been developed having an extremely high aspect ratio and a structure similar to C60.

1 is a cross-sectional view schematically showing a cross-sectional structure of a unit CNT electron gun of a conventional field emission array having one gate electrode.

A cathode insulating layer 3 having a cathode electrode 2 formed on the substrate 1 and having an opening 3a covering a portion of the cathode electrode 2 and exposing a central portion of the cathode electrode 2 is provided. Formed. On the cathode insulating layer 3, a gate insulating layer 4 and a gate electrode 5 each having a larger through hole 4a and a gate hole 5a than the opening 3a of the cathode insulating layer 3 are formed. have.

On the other hand, a grown or coated CNT emitter 8 is provided on the upper surface of the cathode electrode 2. In FIG. 1, reference numeral “9” is a front substrate, 9b is an anode electrode, and 9c is a phosphor layer.

2 schematically illustrates the cross-sectional structure of a unit CNT electron gun of a conventional field emission array having two gate electrodes. This electron gun has a structure in which a second gate insulating layer 6 and a second gate electrode 7 on the upper surface thereof are added to the electron gun shown in FIG. Specifically, on the cathode insulating layer 3, the first gate insulating layer 4 and the first gate insulating layer 4 having the large through light 4a and the first gate hole 5a are larger than the opening 3a of the cathode insulating layer 3. One-gate electrode 5 is formed. The second gate insulating layer 6 has a larger through hole 6a and a second gate hole 7a than the first gate hole 5a of the first gate electrode 5 on the first gate electrode 5. And a second gate electrode 7 is formed. On the other hand, a grown or coated CNT emitter 8 is provided on the upper surface of the cathode electrode 2. The second gate electrode 7 may also be referred to as a double gate electrode or a focus gate electrode, and the second gate insulating layer 6 may also be referred to as a focus gate insulating layer.

Unlike the field emission device shown in FIG. 1, the field emission device having the structure shown in FIG. 2 has two first and second gate electrodes 5 and 7 to control electronics such as internal arcing prevention and effective focusing. Is possible.

FIG. 3 is a diagram illustrating an array of the field emission devices shown in FIG. 2.

Referring to FIG. 3, a plurality of stripe cathode electrodes 2 are disposed on the back substrate 1 to be spaced apart from each other by a predetermined distance. The gate electrode 5 is arranged in the direction perpendicular to the array direction of the cathode electrode 2, and has one focus gate hole corresponding to the fluorescent layer 9c that emits one color, that is, one subpixel 9c. 7a is formed, and a plurality of gate holes 5a are formed below each focus gate hole 7a. One CNT emitter 8 is formed in the gate hole 5a. The plurality of CNT emitters 8 formed in one focus gate hole 7a form a unit CNT emitter. The corresponding fluorescent layer emits light in accordance with the signal electrode from the cathode electrode 2.

Accordingly, the field emission display device having the field emission device of FIG. 3 has one fluorescent layer 9c (R, G, B) from one unit CNT emitter 8, that is, one as shown in FIG. Subpixels correspond to 1: 1.

Meanwhile, a method of exciting fluorescent layers corresponding to one pixel, that is, three subpixels with one unit electron gun has been proposed. That is, as shown in FIG. 5, the electron beams emitted from one unit CNT emitter 8 are switched to the anode electrodes 9d below the fluorescent layers R, G, and B for each color, and the respective color fluorescent layers R, G To B) in turn.

However, when switching the anode electrode 9d, the residual voltage is generated due to the several kV high voltage switching of the anode electrode 9d, and thus, some electron beams are directed to the adjacent fluorescent layer, thereby degrading color purity and luminance. There was.

An object of the present invention is to provide a CNT field emission device and a field emission display device capable of controlling the direction of the electron beam emitted from the CNT emitter.

In order to achieve the above object, the field emission device according to the present invention is:

A gate insulating layer formed on the substrate in a stripe shape in one direction and having a plurality of unit CNT emitters arranged thereon; a gate insulating layer having through holes through which electrons emitted from the unit CNT emitters pass; A field emission device comprising: a gate electrode having a gate hole defining a passage of electrons on a layer; and a focus gate electrode configured to focus an electron beam spaced upwards from the gate electrode by a predetermined distance, the field emission device comprising:

The focus gate electrode includes first and second electrodes formed to face each other in a vertical direction with respect to the cathode electrode at both ends of the cathode electrode, and between the cathode electrode and the side of the first and second electrode facing each other. The comb electrodes are formed to extend in parallel in the direction facing each other.

In order to achieve the above object, the field emission display device according to the present invention includes:

A gate insulating layer having a plurality of cathode electrodes formed in a stripe shape in one direction on the rear substrate and having a plurality of unit CNT emitters arranged thereon, a through hole through which electrons emitted from the unit CNT emitters pass, and the gate A gate electrode having a gate hole defining a passage of the electrons on an insulating layer, a focus gate electrode focusing an electron beam spaced upwards from the gate electrode by a predetermined distance, and spaced apart from the rear substrate by a predetermined distance forwardly; In a field emission display device having a front substrate on which an anode electrode and a fluorescent layer are laminated on opposite surfaces,

The focus gate electrode includes first and second electrodes formed to face each other in a vertical direction with respect to the cathode electrode at both ends of the cathode electrode, and between the cathode electrode and the side of the first and second electrode facing each other. The comb electrodes are formed to extend in parallel in the direction facing each other.

It is preferable that an insulating layer having a predetermined thickness is formed between the gate electrode and the focus gate electrode.

The fluorescent layer in the region corresponding to the unit CNT emitter is composed of regions displaying red subpixels, green subpixels, and blue subpixels.

The electron beam from the unit CNT emitter is a fluorescent layer of any one subpixel area among the areas displaying the red subpixel, the green subpixel, and the blue subpixel according to the voltage applied to the first electrode and the second electrode. Emit light.

Hereinafter, preferred embodiments of the field emission device and the field emission display device according to the present invention will be described in detail with reference to the accompanying drawings. First, the field emission device according to the present invention includes a plurality of side-by-side cathode and gate electrodes arranged in an X-Y matrix, and the stacked structure of the cathode and gate electrodes and the CNT emitters provided at the intersection thereof is basically It may be substantially the same as the conventional field emission device described above, or may be the same as other field emission devices known in the art. Therefore, the detailed basic structure of the present invention having this technical background will not be described in depth, and the technical features of the field emission device according to the present invention will become apparent from the detailed description below.

FIG. 6 is a schematic plan view of the field emission device array according to the present invention, and the stacked structure thereof refers to the structure of FIG. 2.

Referring to FIG. 6, on the rear substrate 1, the cathode electrode 2 in the first direction (vertical direction in the drawing) and the gate electrode 5 in the second direction (horizontal direction in the drawing) are arranged in a direction perpendicular to each other. The gate insulating layer 4 is provided between them. In addition, seven CNT emitters 8 are provided at the intersection between the cathode electrode 2 and the gate electrode 5, but according to other embodiments, only one or more may be formed. . The plurality of CNT emitters formed at these intersections form unit CNT emitters corresponding to one fluorescent layer (subpixel).

The CNT emitter 8 is formed on the cathode electrode 2, and the gate electrode 5 has a gate hole 5a corresponding to each of the CNT emitters 8. In addition, the insulating layer 4 electrically insulates the gate electrode 5 and the cathode electrode 2 as in a general field emission device, and provides a through hole 4a corresponding to the CNT emitter 8. Have Here, the cathode insulating layer 3 and the gate insulating layer 4 of FIG. 2 may be formed of one insulating layer.

The focus gate electrode is an electrode that controls the trajectory of electrons extracted by the gate electrode 5. The focus gate electrode is composed of first and second electrodes 11 and 12. These electrodes 11 and 12 respectively extend in the direction perpendicular to the direction of the cathode electrode 2 at both ends of the cathode electrodes 2 and are arranged to face each other. On the opposite sides of these electrodes 11 and 12, comb electrodes 11a and 12a which extend in parallel to the cathode electrode 2 alternately with each other with the cathode electrode 2 therebetween are formed.

When the voltage applied to the first electrode 11 and the voltage applied to the second electrode 12 are the same, the electron beam goes straight in FIG. 5 to emit the green fluorescent layer G. FIG. Subsequently, when an electrode relatively higher than the second comb electrode 12a is applied to the first comb electrode 11a, the electron beam is focused in the direction of the first comb electrode 11a to emit the red fluorescent layer R of FIG. 5. . Conversely, when an electrode relatively higher than the first comb electrode 11a is applied to the second comb electrode 12a, the electron beam is focused in the direction of the second comb electrode 12a to emit the blue fluorescent layer B of FIG. Let's do it. Therefore, the trajectory direction of the electron beam can be controlled by switching the first and second electrodes 11 and 12 of the focus gate electrode to a predetermined voltage, so that the unit CNT emitter 8 corresponds to one pixel. That is, it can be used corresponding to the three sub-pixels.

7 is an explanatory diagram showing an example of a switching circuit of the field emission device according to the present invention.

Referring to FIG. 7, the first electrode 11 and the second electrode 12 may be switched on three wires, respectively. When the first and second electrodes 11 and 12 are connected in the red mode R as shown in FIG. 7, the first electrode 11 is connected to the 11 V voltage source 13, and the second electrode 12 is − It is connected to a 42 V voltage source 14, so that the electron beam is adjusted in the direction of the first electrode 11 to excite the red fluorescent layer R.

FIG. 8 is a diagram showing a result of simulation of the trajectories of electrons when a predetermined voltage is applied to the first and second electrodes 11 and 12 under the above conditions under a gate voltage of 180 V and an anode voltage of 2.5 kV. . 8, it can be seen that electrons emitted from the CNT emitter 8 are focused toward the first electrode 11 having a high focus gate voltage.

Referring back to FIG. 7, when the first and second electrodes 11 and 12 are connected in the green mode, the first electrode 11 and the second electrode 12 are connected to the same voltage source (-42V) 14. Thus, the electron beam is focused between the first comb electrode 11a and the second comb electrode 12a to go straight to emit the green fluorescent layer.

FIG. 9 is a diagram illustrating a result of a simulation of electron trajectories when the same voltage (-11 V) is applied to the first and second electrodes 11 and 12 under a gate voltage of 180 V and an anode voltage of 2.5 kV. . 9, it can be seen that electrons emitted from the CNT emitter 8 are focused by the focus gate voltage and travel in a straight direction.

10 is an explanatory diagram showing another example of a switching circuit of the field emission device according to the present invention.

Referring to FIG. 10, the first electrode 11 and the second electrode 12 may be switched with three wires, each of which is an 11 V voltage source 15, a -11 V voltage source 16,- Is connected to a 42 V voltage source 17. When the first and second electrodes 11 and 12 are connected in the red mode as shown in FIG. 10, the first electrode 11 is connected to the 11 V voltage source 15, and the second electrode 12 is connected to the -42 V voltage source. And the electron beam is focused in the direction of the first electrode to excite the red phosphor layer (R).

FIG. 11 shows the first and second electrodes 11 and 12 under conditions of switching to a red mode (Pos 1), a green mode (Pos 2), and a blue mode (Pos 3) at a gate voltage of 180 V and an anode voltage of 2.5 kV. Is a diagram showing the results of simulating the trajectory of electrons when a predetermined voltage is applied to the circuit. It can be seen that the electron beams in each mode are focused on the corresponding fluorescent layers R, G, and B separately from each other.

According to the present invention, the fluorescent layers of three subpixels corresponding to one unit CNT emitter may be emitted by switching two spaced focus gate electrodes. In particular, since the voltage switching to the focus gate electrode is a low voltage, it is easy to switch the voltages differently from each other. In addition, when assembling the front substrate to the rear substrate having the electron-emitting device does not require a high degree of accuracy. This is because even if the assembly is shifted slightly, the switching voltage can adjust the electrons to reach the desired fluorescent layer.

On the other hand, the number of cathode electrodes and data driver ICs connected to the respective cathode electrodes are reduced by one third, thereby reducing manufacturing costs.

Although the present invention has been described with reference to the embodiments with reference to the drawings, this is merely exemplary, it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined only by the appended claims.

1 is a cross-sectional view schematically showing a cross-sectional structure of a unit CNT electron gun of a conventional field emission array having one gate electrode.

2 is a cross-sectional view schematically showing a cross-sectional structure of a unit CNT electron gun of a conventional field emission array having two gate electrodes.

3 is a plan view schematically illustrating an array of the field emission devices shown in FIG. 2.

FIG. 4 is a diagram illustrating excitation of a fluorescent layer by 1: 1 correspondence with an electron gun of the prior art. FIG.

FIG. 5 is a diagram illustrating sequentially excitation of three fluorescent layers with one electron gun. FIG.

6 is a schematic plan view of a field emission device array according to the present invention.

7 is an explanatory diagram showing an example of a switching circuit of the field emission device according to the present invention.

FIG. 8 is a diagram illustrating a result of simulation of a trajectory of electrons when different voltages are applied to a first electrode and a second electrode of a focus gate electrode of the present invention.

FIG. 9 is a diagram illustrating a result of simulating the trajectories of electrons when the same voltage is applied to the first electrode and the second electrode of the focus gate electrode of the present invention.

10 is an explanatory diagram showing another example of a switching circuit of the field emission device according to the present invention.

FIG. 11 is a diagram illustrating a result of simulating a trajectory of electrons when switching a voltage applied to a first electrode and a second electrode of a focus gate electrode of the present invention.

* Description of Signs of Major Parts of Drawings *

1: substrate (back substrate) 2: cathode electrode

3: cathode insulating layer 4: gate insulating layer

5: gate electrode 5a: gate hole

6: focus gate insulating layer 7: focus gate electrode

8: CNT emitter (unit CNT emitter) 9: Front electrode

9b, 9d: anode electrode 9c: fluorescent layer

11: first electrode 11a, 12a: comb electrode

12: second electrode 13 ~ 17: voltage source

Claims (6)

A gate insulating layer formed on the substrate in a stripe shape in one direction and having a plurality of unit CNT emitters arranged thereon; a gate insulating layer having through holes through which electrons emitted from the unit CNT emitters pass; A field emission device comprising: a gate electrode having a gate hole defining a passage of electrons on a layer; and a focus gate electrode configured to focus an electron beam spaced upwards from the gate electrode by a predetermined distance, the field emission device comprising: The focus gate electrode includes first and second electrodes formed to face each other in a vertical direction with respect to the cathode electrode at both ends of the cathode electrode, and between the cathode electrode and the side of the first and second electrode facing each other. And a comb electrode extending side by side in a direction facing each other. The method of claim 1, And a dielectric layer having a predetermined thickness between the gate electrode and the focus gate electrode. A gate insulating layer having a plurality of cathode electrodes formed in a stripe shape in one direction on the rear substrate and having a plurality of unit CNT emitters arranged thereon, a through hole through which electrons emitted from the unit CNT emitters pass, and the gate A gate electrode having a gate hole defining a passage of the electrons on an insulating layer, a focus gate electrode focusing an electron beam spaced upwards from the gate electrode by a predetermined distance, and spaced apart from the rear substrate by a predetermined distance forwardly; In a field emission display device having a front substrate on which an anode electrode and a fluorescent layer are laminated on opposite surfaces, The focus gate electrode includes first and second electrodes formed to face each other in a vertical direction with respect to the cathode electrode at both ends of the cathode electrode, and between the cathode electrode and the side of the first and second electrode facing each other. And a comb electrode extending side by side in a direction facing each other on the field emission display device. The method of claim 3, wherein And an insulating layer having a predetermined thickness is formed between the gate electrode and the focus gate electrode. The method of claim 3, wherein And the fluorescent layer in the region excited by the unit CNT emitter is configured to display a red subpixel, a green subpixel, and a blue subpixel, respectively. The method of claim 5, The electron beam from the unit CNT emitter is a fluorescent layer of any one of the subpixel areas of the red subpixel, the green subpixel, and the blue subpixel according to the voltage applied to the first electrode and the second electrode. A field emission display device characterized by emitting light.