KR100869790B1 - Field emission display device - Google Patents

Abstract

The present invention relates to a field emission display device that controls the path of an electron beam emitted from an emitter toward a fluorescent film of a corresponding pixel to realize a clear image quality, and increases the luminance of the screen by increasing the amount of the electron beam that reaches the fluorescent film.

The field emission display device includes gate electrodes formed in a stripe pattern on a first substrate; An insulating layer formed on the first substrate while covering the gate electrodes; Cathode electrodes formed on the insulating layer in a stripe pattern orthogonal to the gate electrode, and having a plurality of through portions located in the intersection area along the gate electrode direction at each intersection area with the gate electrode; A plurality of emitters disposed in the through portion of the cathode electrode along the cathode electrode direction and electrically connected to the cathode electrode; A transparent anode electrode formed on the second substrate; And fluorescent films formed on the anode electrode.

Field emission, emitter, color purity, cathode, gate, anode, metal grid, fluorescent film

Description

Field emission display device {FIELD EMISSION DISPLAY DEVICE}

1 is a partially exploded perspective view of a field emission display device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the field emission display viewed in the direction of arrow A of FIG. 1.

3 is a partial plan view of the rear substrate shown in FIG. 1.

4 is a schematic diagram showing an electron beam emission trajectory obtained through computer simulation in the field emission display according to the first embodiment of the present invention.

5 is a partial plan view of a rear substrate of a field emission display device according to a second exemplary embodiment of the present invention.

6 is a schematic diagram showing an electron beam emission trajectory obtained through computer simulation in the field emission display according to the second exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission display device, and more particularly, to a field emission display device in which a plurality of emitters are arranged in one pixel area using a carbon-based material, in particular, carbon nanotubes (CNTs). It is about.

In the field of field emission display (FED), Emi is a source of electron emission through a thick film process such as screen printing using a carbon-based material that emits electrons well under low voltage (approximately, 10 to 100V) driving conditions. Research and development of technology to form the flat even.

According to the technical trends so far, suitable carbon-based materials for flat emitters are graphite, diamond, diamond liked carbon (DLC) and carbon nanotubes, among which carbon nanotubes have a radius of curvature at their ends. Due to this fine shape characteristic, it is expected to emit electrons well even at a low electric field of about 1 to 10 V / mu m and is expected to be an ideal electron emission material.

When the field emission display device has a triode structure having a cathode, an anode, and a gate electrode, a conventional field emission display device first forms a cathode electrode on a substrate on which an emitter is disposed, and then emits an emission on the cathode electrode. After the emitter is disposed, the gate electrode is disposed over the emitter.

However, in the above-described general triode structure, there is a manufacturing difficulty in filling the emitter material into the holes formed in the gate electrode and the insulating layer under the gate electrode, and in addition, electrons emitted from the emitter during the actual driving process are electron beamed. In this case, the electron beam divergence becomes stronger under the influence of the positive voltage applied to the gate electrode, and the electron beam spreads.

As a result, the electron beam emitted from one emitter emits not only the fluorescent film of the corresponding pixel but also the fluorescent film of another pixel that is not desired, thereby degrading the color purity of the screen, thereby making it impossible to realize vivid image quality.

In view of these problems, conventionally, efforts have been made to provide excellent control of the focusing of the electron beam emitted from the emitter by installing a metal grid in the form of a mesh between the gate electrode and the anode electrode. And field emission display devices disclosed in 2000-268704.

In addition to the above-described advantages, the metal grid has an additional advantage of preventing damage to the configuration of the back substrate including the emitter when arcing occurs due to the high voltage applied to the anode electrode of the device. When the electron beam is emitted, the electron beam does not pass through the hole of the metal grid, but the electron beam is shielded by hitting the metal grid, so the utilization efficiency of the electron beam is reduced, and the amount of the electron beam that reaches the fluorescent film is reduced, thereby reducing the brightness of the screen There is this.

This problem especially arises in a structure in which the gate electrode is disposed below the cathode electrode and the emitter is disposed above the cathode electrode, as in the field emission display device disclosed in US Pat. No. 6,420,726 proposed by the applicant of the present invention. There are many possibilities.

This is because the emission of the electron beam is most likely at the edge of the emitter and the electron beam tends to propagate along the parabolic trajectory toward the front substrate, so that all the electron beam emitted from one emitter passes through the hole of the metal grid intact. If not, the amount of the electron beam for emitting the corresponding fluorescent film is greatly reduced.                         

Furthermore, in the above-described structure, one emitter is positioned at one edge of the cathode electrode for each pixel, and a strong electric field is concentrated at the edge of each emitter, and electrons are emitted therefrom, so the electron emission characteristics of the emitter are nonuniform. There is a problem that it is difficult to control the light emission characteristics uniformly, there is a limit in increasing the amount of the electron beam to reach the fluorescent film because the electron beam emission region of the emitter is narrow.

In addition, in the above-described structure, since one emitter is arranged for each pixel, the current load applied to each emitter is very large, causing the emitter to be damaged during long periods of operation in a high current region, resulting in low emitter lifetime reliability. have.

Therefore, the present invention is to solve the above problems, an object of the present invention is to control the path so that the electron beam emitted from the emitter toward the fluorescent film of the pixel to implement a clear image quality, the electron beam reaching the fluorescent film The present invention provides a field emission display device capable of increasing the brightness of a screen by increasing the amount of light and improving the lifetime reliability of the emitter.

In order to achieve the above object, the present invention,

Gate electrodes formed in a stripe pattern on the first substrate, an insulating layer formed on the first substrate while covering the gate electrodes, and a stripe pattern orthogonal to the gate electrode on the insulating layer, and crossing regions with the gate electrodes. Cathodes each having a plurality of penetrating portions located in the intersection region along the gate electrode direction, a plurality of emitters electrically connected to the cathode electrode and disposed in the cathode electrode through the cathode electrode direction; A field emission display including a transparent anode electrode formed on a substrate and a fluorescent film formed on the anode electrode is provided.

The emitters are in close contact with the side of the cathode electrode and electrically connected to the cathode electrode, and are formed in a single transverse unit extending along the cathode electrode direction.

Preferably, the penetrations and emitters in the cross section are symmetrical with respect to the centerline connecting the center of the cathode along the direction of the cathode.

To this end, the cathode electrode has first through third through portions formed in the intersection area, and each through portion has a rectangular shape having two horizontal sides in the direction of the cathode electrode.

The first and second emitters are positioned along two horizontal sides of the second through part at random intervals, and one horizontal side adjacent to the edge of the cathode electrode is provided between the two horizontal sides provided at the first through part and the third through part, respectively. Along the third and fourth emitters.

In another embodiment, the cathode electrode has first, second, third, and fourth through portions formed in an intersection area, wherein each of the through portions has a rectangular shape having two horizontal sides along the direction of the cathode electrode. The first and second penetrations are located above the centerline and the third and fourth penetrations are below the centerline.

The first and second emitters are positioned along one horizontal edge adjacent to the upper edge of the cathode electrode among the two horizontal edges respectively provided in the first and second through portions, and the third and fourth through portions are provided. The third and fourth emitters are positioned along one horizontal edge adjacent to the lower edge of the cathode electrode among the two horizontal edges.

The emitter is made of any one or combination of carbon nanotubes, graphite, diamond, diamond-like carbon, C ₆₀ (fulleren), a metal grid in the form of a mesh is disposed between the cathode electrode and the anode electrode to focus the electron beam Let's do it.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a partially exploded perspective view of a field emission display device according to a first exemplary embodiment of the present invention, and FIG. 2 is a partially combined cross-sectional view of the field emission display device viewed from the direction of arrow A of FIG. 1.

As shown, the field emission display device includes a first substrate (hereinafter referred to as a 'back substrate' for convenience) and a second substrate (hereinafter referred to as a 'front substrate' for convenience) disposed to face each other at arbitrary intervals to have an internal space. And a structure for emitting electrons by forming an electric field on the rear substrate 2 and a configuration for implementing a predetermined image by the electrons on the front substrate 4.

More specifically, the transparent gate electrodes 6 are formed on the rear substrate 2 in a stripe pattern along one direction (Y direction in the drawing) of the rear substrate 2, and cover the gate electrodes 6 while covering the rear substrate. In front of (2) a transparent insulating layer 8 is placed with any thickness. On the insulating layer 8, opaque cathode electrodes 10 are formed in a stripe pattern along a direction orthogonal to the gate electrode 6 (X direction in the drawing).

In the present exemplary embodiment, when the pixel area of the field emission display device is defined as an intersection area between the gate electrode 6 and the cathode electrode 10, the surface of the insulating layer 8 is exposed to the cathode electrode 10 for each pixel area. A plurality of through parts 12 are formed. The through parts 12 are preferably arranged in a line along the gate electrode direction (Y direction in the drawing). In the present embodiment, three through parts forming an odd number will be described as an example.

When the three through parts are named as first through third through parts 12a, 12b and 12c, the shape of the through parts 12 is in the cathode electrode direction (X direction in the drawing) as shown in FIG. A rectangular shape having a horizontal side along the vertical side along the gate electrode direction (X direction in the drawing) is preferable, and an imaginary center line connecting the center of the cathode electrode 10 along the cathode electrode direction (indicated by a B line in the figure). It is positioned to be vertically symmetric with respect to.

Here, the emitters to be described later are located on the horizontal sides of the first to third through parts 12a, 12b, and 12c, so that the emitters can secure a sufficient electron emission area so that the horizontal parts of the through parts 12 are horizontal. It is preferable to form the sides to a sufficient length.

In addition, a plurality of emitters 14 are formed on the insulating layer 8 in the first to third through parts 12a, 12b, and 12c along the cathode electrode direction. In this case, since the emitters 14 should be electrically connected to the cathode electrode 10, the emitters 14 may be disposed in close contact with the side surfaces of the cathode electrode 10 along the horizontal sides of the first through third through parts 12a, 12b, and 12c. Electrical contact is realized by contacting the side surface of the cathode electrode 10, and each emitter 14 is formed of a single cross-section unit extending along the cathode electrode direction (X direction in the drawing).                     

The emitters 14 are preferably positioned symmetrically with respect to the above-described center line (B line). This is because when the emitters 14 are arranged symmetrically with respect to any one pixel, the electron beam emitted from the emitters 14 is not uniformly directed in a certain part of the direction but in a uniform distribution toward the front substrate 4. Because you can proceed.

In this embodiment, for this purpose, the first and second emitters 14a and 14b are positioned at random intervals along the two horizontal sides of the second through part 12b in the second through part 12b in the center. In the first through part 12a and the third through part 12c, the third and fourth emitters 14c and 14d are positioned along one horizontal side adjacent to the edge of the cathode electrode 10. Thus, in the present embodiment, four emitters 14 are positioned symmetrically in each pixel area.

The emitter 14 is formed in a flat shape having a thickness larger than that of the cathode electrode 10. In the present invention, the emitter 14 is made of a carbon-based material, such as carbon nanotubes, graphite, diamond, diamond-like carbon, C ₆₀ (fulleren) or a combination thereof, and in this embodiment, carbon nanotubes are applied. Doing.

On the other hand, one surface of the front substrate 4 facing the rear substrate 2, along with the transparent anode electrode 16, along the vertical direction of the screen, that is, the gate electrode direction (Y direction in the drawing) R, G, B fluorescent film The fields 18 are positioned at random intervals, and a black matrix film 20 for contrast enhancement is positioned between each of the R, G, and B fluorescent films 18.

Furthermore, the metal thin film layer 22 made of aluminum or the like may be positioned on the fluorescent film 18 and the black matrix film 20. The metal thin film layer 22 serves to improve the breakdown voltage characteristics and luminance of the field emission display device.

The front substrate 4 and the rear substrate 2 constituted as described above are joined by a sealing material at arbitrary intervals while the cathode electrode 10 and the fluorescent film 18 face each other to cross each other, and between them. By exhausting the formed internal space and maintaining in a vacuum state, the field emission display device is constructed.

In addition, a metal grid 24 having a mesh shape having a plurality of holes 24a is positioned in the vacuum container formed by the front substrate 4 and the rear substrate 2. The metal grid 24 prevents damage to the rear substrate 2 when arcing occurs in the vacuum vessel and serves to focus electrons emitted from the emitter 14.

In this case, a plurality of upper spacers 26 are disposed in the non-pixel region between the front substrate 4 and the metal grid 24 to maintain a constant distance between the front substrate 4 and the metal grid 24. In the non-pixel region between the rear substrate 2 and the metal grid 24, a plurality of lower spacers 28 are disposed to maintain a constant distance between the rear substrate 2 and the metal grid 24.

The field emission display device configured as described above is driven by supplying a predetermined voltage to the gate electrode 6, the cathode electrode 10, the anode electrode 16, and the metal grid 24 from the outside. (6) is a positive voltage of several to several tens of volts, a positive voltage of several to several tens of volts to the cathode electrode 10, a positive voltage of several hundred to several thousand volts to the anode electrode 16, and Positive voltages of tens to hundreds of volts are applied to the metal grid 24.                     

As a result, an electric field is formed around the emitter 14 due to the voltage difference between the gate electrode 6 and the cathode electrode 10, and electrons are emitted therefrom. In this embodiment, four emitters 14a to each pixel area are emitted. Since 14d) is disposed, an electric field is concentrated at the edges of the four emitters 14a to 14d, and electrons are emitted from the same at the same time.

As such, the electron beams emitted from the emitter 14 are intimately passed through the holes 24a of the metal grid 24 while being directed to the front substrate 4 by the positive voltage applied to the metal grid 24. The fluorescent film 18 emits light by colliding with the fluorescent film 18 by being attracted by the high voltage applied to the anode electrode 16.

In this case, in the field emission display device according to the present exemplary embodiment, the emitters 14 are arranged along the direction of the cathode electrode and are arranged to be vertically symmetric with respect to the above-described center line (B line). The electron beams emitted from the X-rays do not diffuse in the horizontal direction (X direction of the drawing) of the screen where the other fluorescent film is located, and draw the emission trajectory along the vertical direction (Y direction of the drawing) of the screen where the same color is located.

In addition, due to the arrangement characteristic of the emitter 14, the third emitter 14c positioned in the first through part 12a emits an electron beam toward the third through part 12c, Since the fourth emitter 14d positioned emits an electron beam toward the first through portion 12a, the electron beams emitted from one pixel region do not extend to the same color fluorescent film located in another pixel. The emission trajectory defined in the fluorescent film 18 region of the pixel is shown.

FIG. 4 is a schematic view showing an electron beam emission trajectory obtained through the computer simulation of the present invention in the field emission display device according to the present embodiment. As shown in FIG. 4, electron beams simultaneously emitted from four emitters 14a to 14d are represented. Scanned with a symmetrical balance towards the center of the fluorescent film 18, the electron beams emitted from one pixel region pass through the holes of the corresponding metal grid 24 intact, and then the fluorescent film 18 of the corresponding pixel. You will only reach.

In view of the above, in the present embodiment, it is expected that the color purity of the screen is improved and the vertical resolution of the screen is improved because other color violations do not occur. In addition, in the present embodiment, since electrons are simultaneously emitted from the edges of the four emitters 14a to 14d, a larger amount of electron beams are provided to the fluorescent film 18 to improve the brightness of the screen, and to each emitter 14 It is expected that the lifetime reliability of the emitter 14 is increased by lowering the applied current load.

FIG. 5 is a partial plan view of a rear substrate of a field emission display device according to a second embodiment of the present invention. In the present embodiment, an even number, for example, four through parts 30a, may be provided for each pixel area of the cathode electrode 10. 30b, 30c, and 30d are arranged in a line along the gate electrode direction (Y direction in the drawing) to expose the surface of the insulating layer 8, and the insulating layer 8 in the first to fourth through portions 30a to 30d. A plurality of emitters 32 are positioned along the cathode electrode direction (X direction in the drawing).

The emitters 32 are arranged up and down symmetrically with respect to the above-described center line (B line). For this purpose, the first and second penetrating portions 30a and 30b positioned above the center line with reference to the drawings are provided at the center lines. The first and second emitters 32a and 32b are positioned along one horizontal edge near the upper edge of the cathode electrode 10 among the two horizontal edges, and the third and fourth through portions 30c positioned below the center line. In 30d), the third and fourth emitters 32c and 32d are positioned along one horizontal side near the lower edge of the cathode electrode 10 among the two horizontal edges provided in each.

Fig. 6 is a schematic view showing electron beam emission trajectories obtained through the computer simulation of the present invention in the field emission display device according to the present embodiment, in which electron beams simultaneously emitted from four emitters 32a to 32d are compared with those of the previous embodiment. It can be seen that the scanning is performed while symmetrically balancing toward the center of the fluorescent film 18 in a more focused state.

Further, it can be seen that the electron beams emitted from one pixel area have reached the fluorescent film 18 of the pixel after completely passing through holes corresponding to the metal grid 24.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As described above, according to the present invention, since the path of the electron beam emitted from the emitter can be controlled toward the fluorescent film of the corresponding pixel, color invasion does not occur and screen color purity is improved and screen vertical resolution is increased. Furthermore, according to the present invention, by providing a larger amount of electron beam to the fluorescent film, the brightness of the screen is improved, and the current load applied to each emitter is lowered to increase the lifetime reliability of the emitter.

Claims (11)

First and second substrates disposed to face each other at arbitrary intervals; Gate electrodes formed on the first substrate in a stripe pattern; An insulating layer formed on the first substrate while covering the gate electrodes; Cathode electrodes formed on the insulating layer in a stripe pattern orthogonal to the gate electrode, and having a plurality of through portions located in the intersection area along the gate electrode direction at each intersection area with the gate electrode; A plurality of emitters disposed in the through portion of the cathode electrode along the direction of the cathode electrode and electrically connected to the cathode electrode; A transparent anode electrode formed on the second substrate opposite the first substrate; And Fluorescent films formed in an arbitrary pattern on the anode electrode Field emission display comprising a. The method of claim 1, And the emitters are in close contact with the side of the cathode electrode in the penetrating portion and electrically connected to the cathode electrode. The method of claim 1, And the emitter is comprised of a monolithic, transverse monolith extending along the cathode electrode direction. The method of claim 1, And a shape symmetry with respect to the center line connecting the centers of the cathode electrodes along the cathode electrode direction in the crossing area. The method of claim 4, wherein And the cathode has first, second, and third through portions formed in the intersection area, and each through portion has a rectangular shape having two horizontal sides in the direction of the cathode electrode. The method of claim 5, The first and second emitters are positioned along two horizontal sides of the second through part at arbitrary intervals, and one horizontal side adjacent to the edge of the cathode electrode among two horizontal sides provided at the first through part and the third through part, respectively. Field emission indicators with third and fourth emitters positioned along the surface. The method of claim 4, wherein And the cathode has first, second, third, and fourth through portions formed in the intersection area, and each through portion has a rectangular shape having two horizontal sides in the direction of the cathode electrode. The method of claim 7, wherein The first and second penetrating portions are positioned above the center line, and the first and second emitters are disposed along one horizontal edge adjacent to the upper edge of the cathode of the two horizontal edges provided at the first and second penetrating portions, respectively. In addition, the third and fourth through parts are positioned below the center line, and the third and fourth through parts are disposed along one horizontal side adjacent to the lower edge of the cathode electrode among the two horizontal sides provided in the third and fourth through parts, respectively. , Field emission indicator with 4 emitters. The method of claim 1, And the emitter is one of carbon nanotubes, graphite, diamond, diamond-like carbon, C ₆₀ (fulleren), or a combination thereof. The method of claim 1, And a metal grid having a mesh shape disposed between the cathode electrode and the anode electrode. The method of claim 10, The field emission display further includes lower spacers disposed in the non-pixel region between the first substrate and the metal grid, and upper spacers disposed in the non-pixel region between the metal grid and the second substrate. Device.

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