KR20070111813A - Electron emission device and electron emission display apparatus having the same - Google Patents

Abstract

An electron emission device and an electron emission display apparatus having the same are provided to emit electrons uniformly from an electron emission source by uniformly distributing a voltage to be applied to the electron emission source. Cathode electrodes(120) and electron emission portions(250) are disposed on a first substrate. Gate electrodes(140) are disposed in such a manner to be electrically insulated from the cathode electrodes. An insulator layer(130) is disposed between the cathode electrodes and the gate electrodes to insulate. Carbon nano tubes(125) are disposed on the cathode electrodes, and are coated with a resistive layer. The gate electrodes are covered by a second insulator layer, and focusing electrodes are disposed in parallel with the gate electrodes.

Description

Electron emitting device and electron emission display apparatus having same TECHNICAL FIELD

1 is a perspective view schematically showing the configuration of a conventional electron emitting device and a display device.

2 is a cross-sectional view taken along the line II-II of FIG.

3 is a cross-sectional view schematically showing the configuration of an electron emitting device and a display device according to the first embodiment of the present invention.

4 is an enlarged view of portion IV of FIG. 3;

5 is a cross-sectional view schematically showing the configuration of an electron emitting device according to a second embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

60: spacer 70: phosphor layer

80: anode electrode 90: second substrate

100, 200: electron emission display device

101: electron emission device

102: front panel 103: light emitting space

110: first substrate 120: cathode electrode

125: carbon nanotubes coated with a resistive layer 130: first insulator layer

131: electron emission source hole 135: second insulator layer

140: gate electrode 145: focusing electrode

150, 250: electron emission source

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron emission element and an electron emission display apparatus having the same. More particularly, the present invention relates to an electron emission element having a new structure in which a voltage applied to an electron emission source is uniformly distributed. The present invention relates to an electron emission display device having the same and improved uniformity between pixels.

In general, an electron emission device includes a method using a hot cathode and a cold cathode as an electron emission source. Examples of electron-emitting devices using a cold cathode include field emitter array (FEA), surface conduction emitter (SCE) type, metal insulator metal (MIM) type, metal insulator semiconductor (MIS) type, and ballistic electron surface emitting (BSE) type. ) And the like are known.

The FEA type uses a principle that electrons are easily released due to electric field difference in vacuum when a material having a low work function or a high β function is used as an electron emission source. Molybdenum (Mo) and silicon A tip structure with a major material such as (Si), a carbon-based material such as graphite, DLC (Diamond Like Carbon), and a recent nano tube or nano wire, etc. Devices have been developed that use nanomaterials as electron emission sources.

The SCE type is a device in which an electron emission source is formed by providing a conductive thin film between a first electrode and a second electrode disposed to face each other on a first substrate and providing a micro crack in the conductive thin film. The device uses a principle that electrons are emitted from an electron emission source that is a micro crack by applying a voltage to the electrodes to flow a current to the surface of the conductive thin film.

The MIM type and the MIS type electron emission devices each form an electron emission source having a metal-dielectric layer-metal (MIM) and metal-dielectric layer-semiconductor (MIS) structure, and are disposed between two metals or metals with a dielectric layer interposed therebetween. When a voltage is applied between semiconductors, a device using the principle of emitting electrons is moved and accelerated from a metal or semiconductor having a high electron potential toward a metal having a low electron potential.

The BSE type uses the principle that electrons travel without scattering when the size of the semiconductor is reduced to a dimension area smaller than the average free stroke of the electrons in the semiconductor, thereby forming an electron supply layer made of a metal or a semiconductor on an ohmic electrode. And an insulator layer and a metal thin film formed on the electron supply layer to emit electrons by applying power to the ohmic electrode and the metal thin film.

Among these, the FEA type electron emission device can be classified into a top gate type and an under gate type according to the arrangement of the cathode electrode and the gate electrode. It can be divided into a pole tube, a triode or a quadrupole. An example of implementing a display device using an FEA type electron emission device is illustrated in FIGS. 1 and 2.

1 is a partial perspective view showing a schematic configuration of a conventional top gate type electron emission display device, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1.

As shown in FIGS. 1 and 2, the conventional electron emission display apparatus 100 includes an electron emission element 101 and a front panel 102 that are arranged side by side to form a light emitting space 103 that is a vacuum. A spacer 60 is provided to maintain a gap between the electron emission element 101 and the front panel 102.

The electron emission device 101 may include a first substrate 110, gate electrodes 140 and cathode electrodes 120 disposed on the first substrate 110, and the gate electrode 140. And an insulator layer 130 disposed between the cathode electrode 120 and the gate electrode 140 to electrically insulate the cathode electrode 120.

Electron emission holes 131 are formed in regions where the gate electrodes 140 and the cathode electrode 120 cross each other, and an electron emission source 150 is disposed therein.

The front panel 102 includes a second substrate 90, an anode electrode 80 disposed on the bottom surface of the second substrate 90, and a phosphor layer 70 disposed on the bottom surface of the anode electrode 80. do.

As described above, when a display device that implements an image by using an FEA type electron emission device is manufactured, luminance uniformity between pixels may be inferior. This is a problem that can occur when the voltage applied to each electron emission source is inconsistent. Such a problem can greatly hinder the quality of the display device, which must be solved to improve the quality of the display device. . Therefore, there is a great need to find a way to solve such a problem that the uniformity between pixels is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to emit electrons uniformly, and an electron emission device having a simple manufacturing process, which reduces manufacturing costs, and thereby providing uniformity between pixels. It is to provide a display device.

An object of the present invention as described above, the first substrate; A cathode electrode and an electron emission unit disposed on the first substrate; A gate electrode disposed to be electrically insulated from the cathode electrode; An insulator layer disposed between the cathode electrode and the gate electrode to insulate the cathode electrode and the gate electrode; It is achieved by providing an electron-emitting device comprising carbon nanotubes coated with a resistive layer and disposed in contact with the cathode electrode.

In addition, the object of the present invention as described above, the first substrate; A plurality of cathode electrodes disposed on the first substrate; A plurality of gate electrodes disposed to intersect the cathode electrodes; An insulator layer disposed between the cathode electrode and the gate electrode to insulate the cathode electrodes and the gate electrodes; An electron emission source hole formed at a point where the cathode electrode and the gate electrode cross each other; An electron emission source including a carbon nanotube disposed in the electron emission hole and coated with a resistance layer; A second substrate disposed substantially parallel to the first substrate; An anode electrode disposed on the second substrate; And a phosphor layer disposed on the anode electrode.

Hereinafter, preferred embodiments of the electron emission device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a view schematically showing the configuration of an electron emission device and a display device implemented using the same according to a first embodiment of the present invention, and FIG. 4 is an enlarged view of part IV of FIG. 3. .

As shown in FIGS. 3 and 4, the electron emission device 200 according to the first embodiment of the present invention may include a first substrate 110, a cathode electrode 120, a gate electrode 140, and a first electrode. The insulator layer 130, the electron emission source 250, and the resistive layer are coated with the carbon nanotubes 125.

The first substrate 110 is a plate-shaped member having a predetermined thickness. Quartz glass, glass containing a small amount of impurities such as Na, plate glass, a glass substrate coated with SiO ₂ , an aluminum oxide, or a ceramic substrate may be used. Can be. In addition, when implementing a flexible display apparatus, a flexible material may be used.

The cathode electrode 120 is disposed to extend in one direction on the first substrate 110 and may be made of a conventional electrically conductive material. For example, metals such as Al, Ti, Cr, Ni, Au, Ag, Mo, W, Pt, Cu, Pd or alloys thereof, glass and metals or metal oxides such as Pd, Ag, RuO ₂ , Pd-Ag It may be made of a printed conductor consisting of a transparent conductor such as In ₂ O ₃ or SnO ₂ , or a semiconductor material such as polysilicon.

The gate electrode 140 may be disposed with the cathode electrode 120 and the insulator layer 130 interposed therebetween, and may be made of a conventional electrically conductive material like the cathode electrode 120.

The insulator layer 130 is disposed between the gate electrode 140 and the cathode electrode 120 to insulate the cathode electrode 120 and the gate electrode 140 to generate a short between the two electrodes. prevent.

The electron emission source 250 is disposed to be energized with the cathode electrode 120, and has a lower height than the gate electrode 140. As the material of the electron emission source 250, any material having a needle-like structure may be used. In particular, it is preferable to be made of carbon-based materials such as carbon nanotubes (CNTs) having a small work function and large beta functions, graphite, diamond and diamond-like carbon. In particular, since the carbon nanotubes have excellent electron emission characteristics and facilitate low voltage driving, the carbon nanotubes are advantageous for the large area of a device using them as an electron emission source.

The carbon nanotubes 125 coated with the resistive layer are disposed to be perpendicular to the electron emission source 250. In particular, the process may be simplified by pasting the carbon nanotubes 125 coated with the resistive layer as shown in FIG. 3, so that the voltage applied to the electron emission source 250 may be uniformly applied. Function. That is, the voltage applied by the coating of the resistive layer on the carbon nanotube drops, and thus a voltage having a small deviation with respect to the entire area is applied in the electron emission source 250, and the adjacent electron emission source ( A voltage having a small deviation between 250 is applied.

The carbon nanotubes 125 coated with the resistance layer form an electron emission source consisting of only carbon nanotubes having a constant resistance value, thereby improving the electron emission uniformity between the carbon nanotubes at a relatively high resistance value. In general, carbon nanotubes synthesized using a metal catalyst are mixed with carbon nanotubes having different electrical resistance values. Therefore, by coating the resistance layer, it is possible to increase the resistance value of the surface of the carbon nanotubes themselves, thereby enabling constant electron emission.

In the carbon nanotubes 125 coated with the resistive layer, the resistive layer preferably has a resistivity of 10 ⁻³ 10cm to 10 ⁵ Ωcm. If the specific resistance value is less than 10 ⁻³ dBm, the effect obtained by making the voltage applied to the cathode electrode uniform by using the resistance layer cannot be obtained. That is, the effect of evenly emitting the electrons in each of the electron emission sources 250, and thus, the effect of preventing the unevenness of the screen and enabling uniform light emission cannot be obtained. In addition, when the resistance value of the carbon nanotubes 125 coated with the resistive layer exceeds 10 ⁵ Pacm, the power consumption is excessively increased and impractical regardless of the effect obtained by forming the resistive layer.

The carbon nanotubes coated with the resistance layer are preferably 80 to 100% by weight of the total carbon nanotube content. If the coated carbon nanotubes are less than 80% by weight, the effect of the resistance layer coating is insignificant, which is not preferable.

On the other hand, the carbon nanotubes coated with the resistance layer may adjust the content and thickness of the resistance layer such that the resistivity uniformity is 80% or more.

The electron emission device 201 having the configuration as described above may apply a negative voltage to the cathode electrode and a positive voltage to the gate electrode to emit electrons from the electron emission source.

On the other hand, the electron emitting device described so far can be used in a display device for generating an image by generating visible light. In order to configure the display device, the second substrate 90 arranged in parallel with the first substrate 110 of the electron emission device according to the present invention, the anode electrode 80 provided on the second substrate 90 and the It further includes a phosphor layer 70 provided on the anode electrode (80).

In addition, the cathode electrode 120 and the gate electrode 140 may be disposed to cross each other in order to implement an image instead of simply generating visible light as a lamp.

Further, electron emission source holes 131 are formed in regions where the gate electrodes 140 and the cathode electrode 120 cross each other, and the electron emission source 250 is disposed therein.

The electron emission device 101 including the first substrate 110 and the front panel 102 including the second substrate 90 face each other while maintaining a predetermined distance therebetween to form a light emitting space. Spacers 60 are arranged to maintain the gap between the emitting element 101 and the front panel 102. The spacer 60 may be made of an insulating material.

In addition, in order to maintain the vacuum inside, the circumference of the space formed by the electron emission element 101 and the front panel 102 is sealed, and the air inside is exhausted.

An electron emission display device having such a configuration operates as follows.

Electrons are emitted from the electron emission source 250 installed on the cathode electrode 120 by applying a negative voltage to the cathode electrode 120 and applying a positive voltage to the gate electrode 140 for electron emission. To be possible. In addition, a strong (+) voltage is applied to the anode electrode 80 to accelerate electrons emitted toward the anode electrode 80. When the voltage is applied in this way, electrons are emitted from the needle-like materials constituting the electron emission source 250, proceed toward the gate electrode 140, and are accelerated toward the anode electrode 80. Electrons accelerated toward the anode electrode 80 hit the phosphor layer 70 positioned on the anode electrode 80 to generate visible light.

Meanwhile, the voltage applied to the electron emission sources constituting the pixel is made uniform by the carbon nanotubes 125 coated with the resistive layer used in the electron emission device of the first embodiment of the present invention, thereby increasing luminance uniformity between pixels. The image quality is improved.

Hereinafter, a method of manufacturing an electron emission device according to a first embodiment of the present invention. The manufacturing method described below is only one embodiment, and is not necessarily to be manufactured by the following method.

First, materials for forming the first substrate 110, the cathode electrode 120, the insulator layer 130, and the gate electrode 140 are sequentially stacked to have a predetermined thickness. Lamination is preferably performed by a process such as screen printing.

Next, a mask pattern is formed on the upper surface of the gate electrode 140 with a predetermined thickness. The mask pattern is formed to form an electron emission hole, and is performed by a photolithography process in which a photoresist (PR) is applied and a pattern is formed using UV or E-beam. .

Next, the gate electrode 140, the insulator layer 130, and the cathode electrode 120 are etched using the mask pattern to form an electron emission hole. The etching process uses wet etching using an etchant, dry etching using an corrosive gas, or an ion beam according to the material and thickness of the gate electrode 140, the insulator layer 130, and the cathode electrode 120. It can be made by a micro machining method.

Next, a carbon paste comprising a carbon material is prepared. Carbon paste prepares the composition separately. As the carbon paste for the electron emission source, a carbon nanotube coated with a resistance layer is used as described above. The carbon nanotube paste coated with the resistive layer is applied to the electron emission hole. Then, the carbon paste for electron emission source is coated on the carbon paste coated with the resistance layer. The application process can be performed by screen printing.

Subsequently, a process of curing a portion of the carbon paste for forming a resistive layer and a portion of the electron paste of forming an electron emitting source are respectively cured.

This process is carried out differently when the carbon paste contains the photosensitive resin and when it is not. First, when the photosensitive resin is contained, an exposure process is used. For example, when a photosensitive resin having negative photosensitivity is included, the negative photosensitive resin has a property of curing upon receiving light, so that after applying the photoresist in a photolithography process, selectively irradiating light to selectively irradiate only a portion of the carbon paste. It is possible to cure to form an electron emission source.

Next, after the exposure, the carbon paste and the photoresist remaining without developing by curing are removed to complete the electron emitting device.

On the other hand, when a carbon paste does not contain photosensitive resin, an electron emission source can be formed by the following method.

When the carbon paste does not contain photosensitive resin, a photolithography process using a separate photoresist pattern is required. That is, a photoresist pattern is first formed using a photoresist film, and then carbon paste is supplied by printing using the photoresist pattern.

The carbon paste printed as described above is subjected to a sintering step in a nitrogen gas atmosphere in which oxygen gas or oxygen of 1000 ppm or less, in particular 10 ppm to 500 ppm, is present. Through the firing step in the oxygen gas atmosphere, the carbon nanotubes in the carbon paste may improve adhesion to the substrate, the vehicle may be volatilized and removed, and other inorganic binders may be melted and solidified, thereby contributing to the durability of the electron emission source. It becomes possible.

The firing temperature should be determined in consideration of the volatilization temperature and time of the vehicle included in the carbon paste. Typical firing temperatures are from 350 ° C to 500 ° C, preferably 450 ° C. If the firing temperature is less than 350 ℃ may cause a problem that the volatilization such as a vehicle is not sufficiently made, if the firing temperature exceeds 500 ℃ may cause a problem that the manufacturing cost increases, the substrate may be damaged.

The calcined product thus fired undergoes an activation step as necessary. According to one embodiment of the activation step, after applying a solution that can be cured in the form of a film through a heat treatment process, for example, an electron emission source surface treatment agent containing a polyimide-based polymer on the firing result, and then heat treatment Then, the film formed by the heat treatment is peeled off. According to another embodiment of the activation step, the activation process may be performed by forming an adhesive part having an adhesive force on the surface of the roller driven by a predetermined driving source and pressing the surface of the firing product at a predetermined pressure. Through this activation step, the nano-sized inorganic material can be controlled to be exposed or vertically oriented to the electron emission source surface.

On the other hand, the carbon paste further includes a vehicle to control the printability and viscosity of the carbon paste in addition to the carbon nanotubes. The vehicle may consist of a resin component and a solvent component.

The resin component may be, for example, a cellulose resin such as ethyl cellulose, nitrocellulose, or the like; Acrylic resins such as polyester acrylate, epoxy acrylate, urethane acrylate and the like; At least one of a vinyl-based resin such as polyvinyl acetate, polyvinyl butyral, polyvinyl ether, and the like may be included, but is not limited thereto. Some of the resin components as described above may simultaneously serve as a photosensitive resin.

The solvent component is, for example, at least one of terpineol, butyl carbitol (BC), butyl carbitol acetate (BCA), toluene and texanol It may include. Among these, it is preferable to contain terpineol.

On the other hand, when the content of the solvent component is too small or too large, there may be a problem that the printability and flowability of the carbon paste is lowered. In particular, when the content of the vehicle is too large, there is a problem that the drying time may be too long.

In addition, the carbon paste may further include one or more selected from a photosensitive resin, a photoinitiator, and a filler, as necessary.

On the other hand, non-limiting examples of the aforementioned photosensitive resins include acrylate monomers, benzophenone monomers, acetophenone monomers, or thioxanthone monomers, and more specifically epoxy acrylates and polyester acrylates. , 2,4-diethyloxanthone, or 2,2-dimethoxy-2-phenylacetophenone can be used.

The photoinitiator serves to initiate crosslinking of the photosensitive resin when the photosensitive resin is exposed. Non-limiting examples of such photoinitiators include benzophenone and the like.

The filler is a material that serves to further improve the conductivity of the inorganic material having a nano-size that is not sufficiently adhered to the substrate, non-limiting examples thereof include Ag, Al, and the like.

Meanwhile, in the foregoing description, only the method of forming the electron emission source using the carbon paste has been described, but in addition to the above method, the electron emission source may be formed using the chemical vapor deposition (CVD) growth method.

5 is a partial cross-sectional view showing a schematic configuration of an electron emitting device according to a second embodiment of the present invention.

As shown in FIG. 5, in the electron emission device according to the second embodiment of the present invention, the second insulator layer 135 and the focusing electrode 145 are added to the structure of the electron emission device of the first embodiment described above. .

The focusing electrode 145 is installed to be electrically insulated from the gate electrode 140 by the second insulator layer 135. In addition, electrons emitted from the electron emission source 250 by the electric field formed by the cathode electrode 120 and the gate electrode 140 may be used as shown in FIGS. 1 to 3 of the front panel 102 as much as possible. It functions to go straight toward the anode electrode (80). The material of the focusing electrode 145 is made of a material having excellent electrical conductivity, similar to the cathode electrode 120 and the gate electrode. In the case of the electron emission device further including the focusing electrode 145, when the carbon nanotube 125 coated with the resistance layer of the present invention is formed, a voltage applied to the electron emission source may be uniformly applied. As a result, electron emission may occur uniformly. In addition, in the display device employing the electron emission device, the electron focusing effect by the focusing electrode and the uniform voltage application effect by the resistive layer are combined to ensure uniformity between pixels.

As described above, according to the present invention, since the voltage applied to the electron emission source is uniformly distributed, the electron emission from the electron emission source occurs uniformly, and the uniformity between pixels in the display device employing the electron emission element is improved. The effect can be obtained.

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

Claims (8)

A first substrate; A cathode electrode and an electron emission unit disposed on the first substrate; A gate electrode disposed to be electrically insulated from the cathode electrode; An insulator layer disposed between the cathode electrode and the gate electrode to insulate the cathode electrode and the gate electrode; An electron emission device disposed in contact with the cathode electrode, comprising a carbon nanotube coated with a resistance layer. The method of claim 1, The resistive layer has a specific resistance value of 10 ⁻³ Ωcm to 10 ⁵ Ωcm. The method of claim 1, The carbon nanotube coated with the resistance layer is an electron emission device, characterized in that 80 to 100% by weight of the total carbon nanotube content. The method of claim 1, A second insulator layer covering an upper side of the gate electrode; And a focusing electrode insulated from the gate electrode by the second insulator layer, and arranged in a direction parallel to the gate electrode. A first substrate; A plurality of cathode electrodes disposed on the first substrate; A plurality of gate electrodes disposed to intersect the cathode electrodes; An insulator layer disposed between the cathode electrode and the gate electrode to insulate the cathode electrodes and the gate electrodes; An electron emission source hole formed at a point where the cathode electrode and the gate electrode cross each other; And An electron emission source including a carbon nanotube disposed in the electron emission hole and coated with a resistance layer; A second substrate disposed substantially parallel to the first substrate; An anode electrode disposed on the second substrate; And And an phosphor layer disposed on the anode electrode. The method of claim 5, And the resistive layer has a resistivity of 10 ⁻³ Ωcm to 10 ⁵ Ωcm. The method of claim 5, The resistive layer-coated carbon nanotube is an electron emission display device, characterized in that 80 to 100% by weight of the total carbon nanotube content. The method of claim 5, A second insulator layer covering an upper side of the gate electrode; And a focusing electrode insulated from the gate electrode by the second insulator layer, and arranged in a direction parallel to the gate electrode.

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