KR20070046541A - Electron emission display device - Google Patents

Abstract

The present invention relates to an electron emission display device capable of increasing display uniformity by minimizing change in electron beam trajectory caused by spacer charging. According to the present invention, an electron emission display device includes a first substrate and a second substrate disposed to face each other, a plurality of electron emission units provided per unit pixel on the first substrate, and an opening for passing an electron beam through the electron emission units. A focusing electrode forming a light emitting diode, a fluorescent layer formed on one surface of the second substrate, and spacers disposed between the first substrate and the second substrate. In this case, the focusing electrode may have a larger number of openings in at least one unit pixel neighboring the spacer than in the unit pixel not neighboring the spacer.

Electron emission unit, spacer, cathode electrode, gate electrode, fluorescent layer, focusing electrode

Description

Electron Emission Display Device {ELECTRON EMISSION DISPLAY DEVICE}

1 is a partially exploded perspective view of an electron emission display device according to an exemplary embodiment of the present invention.

2 is a partial cross-sectional view of an electron emission display device according to an embodiment of the present invention.

3 is a partial plan view of the electron emitting device shown in FIG. 1.

FIG. 4 is a schematic diagram showing an electron beam spot shape expected in the unit pixel configuration shown in FIG. 3.

FIG. 5 is a partial plan view illustrating an electron emission display device of a comparative example in which a focusing electrode forms one opening per unit pixel. FIG.

FIG. 6 is a schematic diagram showing an electron beam spot shape expected in the unit pixel configuration shown in FIG. 5.

The present invention relates to an electron emission display device, and more particularly, to an electron emission display device having spacers disposed inside a vacuum vessel to support a vacuum compression force.

In general, electron emission elements may be classified into a method using a hot cathode and a cold cathode according to the type of electron source.

Here, the electron-emitting device using the cold cathode is a field emitter array (FEA) type, a surface conduction emission type (SCE) type, a metal-insulation layer-metal Metal (MIM) type and Metal-Insulator-Semiconductor (MIS) type are known.

The electron emission elements are arranged in an array on one substrate to form an electron emission device, and the electron emission device is combined with another substrate provided with a light emitting unit composed of a fluorescent layer and an anode electrode, and the electron emission display device. (electron emission display device) is configured.

In the electron emission display device, the first substrate on which the electron emission elements are disposed and the second substrate on which the light emitting unit is provided are integrally bonded at their edges by a sealing member, and then the internal space is evacuated to a vacuum of approximately 10 ^-6 torr and sealed. A vacuum container is constituted with the member. The vacuum container receives a strong compressive force due to the pressure difference between the inside and the outside, and the compressive force increases in proportion to the screen size.

Therefore, a technique of providing a plurality of spacers between the first substrate and the second substrate to support the compressive force applied to the vacuum container and to keep the distance between the two substrates constant has been developed and used. In this case, the spacer is made of a material having high strength and non-conductivity, such as glass or ceramic, and is positioned corresponding to the black layer so as not to invade the fluorescent layer.

However, even when the electron emission display device is provided with a focusing electrode, it is difficult to ensure perfect electron beam straightness, and when electrons emitted from the electron emission portion of the first substrate are directed to the second substrate on which the fluorescent layer is located, It spreads with divergence angle. The electron beam spreading causes electrons to collide on the surface of the spacer, and the spacer on which the electrons collide is charged with a positive or negative potential according to the material properties (dielectric constant, secondary electron emission coefficient, etc.).

Charged spacers distort the electron beam path by changing the electric field around the spacers. For example, a spacer charged at a positive potential attracts an electron beam, and a spacer charged at a negative potential pushes the electron beam. Therefore, the electron beam movement trajectory is changed in the unit pixel around the spacer so that the electron beam spot reaching the second substrate is attracted or pushed away from the spacer.

As a result, there is a difference in the shape of the electron beam spot between the spacer, the neighboring unit pixel, and the other unit pixel, which causes a decrease in display uniformity, hinders accurate color implementation around the spacer, and causes a degradation in display quality in which the spacer is perceived on the screen. do.

Accordingly, an object of the present invention is to provide an electron emission display device capable of increasing display uniformity by minimizing change in electron beam trajectory caused by spacer charging.

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

A first substrate and a second substrate disposed to face each other, a plurality of electron emitters provided per unit pixel on the first substrate, a focusing electrode positioned on the electron emitters and forming an opening for passing an electron beam, and a second Fluorescent layers formed on one surface of the substrate, and spacers disposed between the first substrate and the second substrate, wherein the focusing electrode has a greater number of unit pixels in the at least one unit pixel neighboring the spacer than in the spacer; Provided is an electron emission display device forming an opening.

The focusing electrode may form one opening for each unit pixel in unit pixels not adjacent to the spacer. In addition, the focusing electrode may form at least two openings having different distances from the spacer in at least one unit pixel adjacent to the spacer.

The electron emission display device further includes cathode electrodes formed on the first substrate and electrically connected to the electron emission parts, and gate electrodes formed in a direction intersecting the cathode electrodes while maintaining insulation from the cathode electrodes. .

In this case, the unit pixels may correspond to the intersection regions of the cathode electrodes and the gate electrodes, and the electron emission units may be disposed in a line along the length direction of one of the cathode electrode and the gate electrode for each unit pixel.

The spacers may be formed in a wall shape and may be spaced apart from each other along a plurality of unit pixels in one direction of the first substrate and another direction perpendicular to the first substrate.

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

1 and 2 are partially exploded perspective and partial cross-sectional views of an electron emission display device according to an exemplary embodiment of the present invention, and FIG. 3 is a partial plan view of the electron emission device shown in FIG. 1.

Referring to the drawings, the electron emission display device includes a first substrate 10 and a second substrate 12 which are disposed in parallel to each other at predetermined intervals. Sealing members (not shown) are disposed at the edges of the first substrate 10 and the second substrate 12 to bond the two substrates, and the internal space is evacuated with a vacuum of approximately 10 ⁻⁶ torr to form the first substrate 10. ), The second substrate 12 and the sealing member constitute a vacuum container.

On the opposite surface of the first substrate 10 to the second substrate 12, electron emission elements are arranged in an array to form the electron emission device 100 together with the first substrate 10, and the electron emission device ( 100 is combined with the second substrate 12 and the light emitting unit 110 provided on the second substrate 12 to form an electron emission display device.

First, the cathode electrodes 14, which are first electrodes, are formed in a stripe pattern along one direction of the first substrate 10 on the first substrate 10, and cover the cathode electrodes 14. 10) The first insulating layer 16 is formed on the whole. Gate electrodes 18, which are second electrodes, are formed on the first insulating layer 16 in a stripe pattern along a direction orthogonal to the cathode electrodes 14.

An intersection area between the cathode electrodes 14 and the gate electrodes 18 forms a unit pixel, and electron emission parts 20 are formed in each unit pixel above the cathode electrodes 14. In addition, openings 161 and 181 corresponding to the electron emission parts 20 are formed in the first insulating layer 16 and the gate electrodes 18, so that the electron emission parts 20 are formed on the first substrate 10. To be exposed.

The electron emission unit 20 may be formed of materials that emit electrons when an electric field is applied in a vacuum, such as a carbon-based material or a nanometer (nm) size material. The electron emission unit 20 may include carbon nanotubes (CNT), graphite, graphite nanofibers, diamonds, diamond-like carbons (DLC), C ₆₀ , silicon nanowires, and combinations thereof. Printing, direct growth, sputtering or chemical vapor deposition (CVD) can be applied.

On the other hand, the electron emission portion may be formed of a tip structure having a pointed tip mainly made of molybdenum (Mo) or silicon (Si).

The electron emission units 20 form two rows per unit pixel, and may be positioned in one line along the length direction of one of the cathode electrode 14 and the gate electrode 18, for example, the cathode electrode 14. The planar shape of each electron emitter 20 may be circular. The arrangement of the electron emission units 20 and the planar shape of the electron emission units 20 for each pixel are not limited to the illustrated example, and may be variously modified.

In addition, in the above, the structure in which the gate electrodes 18 are positioned on the cathode electrodes 14 with the first insulating layer 16 therebetween has been described, but the gate electrodes have the first insulating layer interposed therebetween. A structure positioned below the electrodes is also possible, in which case the electron emission parts may be formed on the side of the cathode electrode over the first insulating layer.

The focusing electrode 22, which is a third electrode, is formed on the gate electrodes 18 and the first insulating layer 16. A second insulating layer 24 is positioned below the focusing electrode 22 to insulate the gate electrodes 18 and the focusing electrode 22, and passes the electron beam through the focusing electrode 22 and the second insulating layer 24. Openings 221 and 241 are provided.

In the present exemplary embodiment, the focusing electrode 22 forms openings 221 and 221 ′ different from each other in the unit pixel neighboring the spacer 26 and the unit pixel that are not the spacer 26 described later.

Next, on one surface of the second substrate 12 opposite to the first substrate 10, the fluorescent layer 28, for example, the red, green, and blue fluorescent layers 28R, 28G, and 28B may be randomly selected from each other. It is formed at intervals, and a black layer 30 is formed between the fluorescent layers 28 to improve the contrast of the screen. The fluorescent layer 28 is disposed so that one fluorescent layer corresponds to each unit pixel set in the first substrate 10.

An anode electrode 32 made of a metal film such as aluminum (Al) is formed on the fluorescent layer 28 and the black layer 30. The anode electrode 32 receives a high voltage required for electron beam acceleration from the outside to maintain the fluorescent layer 28 in a high potential state, and is emitted toward the first substrate 10 of the visible light emitted from the fluorescent layer 28. The visible light is reflected toward the second substrate 12 to increase the brightness of the screen.

On the other hand, the anode electrode may be made of a transparent conductive film such as indium tin oxide (ITO) rather than a metal film. In this case, the anode is positioned on one surface of the fluorescent layer 28 and the black layer 30 facing the second substrate 12. Moreover, the structure which uses simultaneously the above-mentioned transparent conductive film and a metal film as an anode electrode is also possible.

In addition, a plurality of spacers 26 are disposed between the first substrate 10 and the second substrate 12 to support the compressive force applied to the vacuum container and to keep the distance between the two substrates constant. The spacers 26 are positioned corresponding to the black layer 30 so as not to invade the fluorescent layer 28.

In the drawing, for example, a wall-type spacer disposed side by side with the gate electrode 18 is illustrated. In FIG. 1, one spacer 26 is illustrated for convenience, but the spacers 26 have a plurality of unit pixels therebetween with the horizontal direction of the screen (the x-axis direction of the drawing) and the vertical direction of the screen (the y-axis of the drawing). Direction, spaced apart from one another.

In the present embodiment, the focusing electrode 22 is a unit not neighboring the spacer 26 in consideration of the electron beam movement trajectory in the unit pixels neighboring the spacer 26 (hereinafter, referred to as 'first unit pixels' for convenience). The openings having different shapes from the pixels (hereinafter, referred to as 'second unit pixels' for convenience) are formed.

That is, in the second unit pixels, the focusing electrode 22 forms one opening 221 for each unit pixel to comprehensively focus electrons emitted from the unit pixel. On the other hand, in the first unit pixels, the focusing electrode 22 forms at least two openings 222 and 223 having different distances from the spacer 26 for each unit pixel so that at least two electrons are emitted from the unit pixel. Gather them in groups and focus them.

In FIG. 3, for example, the focusing electrode may include a first opening 222 having a separation distance between the spacer 26 and d1 and a second opening 223 having a separation distance between the spacer 26 and d2 in the first unit pixel. And a bridge 224 formed between the first opening 222 and the second opening 223 in the center of the unit pixel. The bridge 224 functions as a focused electric field barrier when the surface of the spacer 26 is charged to a positive potential, for example, to attract electrons emitted inside the second opening 223 toward the charged spacer 26. It acts as a deterrent.

The electron emission display device having the above-described configuration is driven by supplying a predetermined voltage to the cathode electrodes 14, the gate electrodes 18, the focusing electrodes 22, and the anode electrodes 32 from the outside.

For example, any one of the cathode electrodes 14 and the gate electrodes 18 receives a scan driving voltage to serve as scan electrodes, and the other electrodes receive a data driving voltage to serve as data electrodes. In addition, the focusing electrode 22 receives a voltage required for electron beam focusing, for example, 0 V or a negative DC voltage of several to several tens of volts, and the anode electrode 32 requires a voltage for accelerating the electron beam, for example, several hundred to several thousand volts. DC voltage of is applied.

As a result, an electric field is formed around the electron emission part 20 in the pixels in which the voltage difference between the cathode electrode 14 and the gate electrode 18 is greater than or equal to the threshold, and electrons are emitted therefrom. The emitted electrons are focused through the openings 221 and 221 ′ of the focusing electrode 22 to the center of the electron beam bundle, and are attracted to the corresponding fluorescent layer 28 by being attracted by the high voltage applied to the anode electrode 32. It emits light.

Despite the action of the focusing electrode 22 during the driving process described above, there are electrons diverging to the periphery of the electron beam bundle, and some of these electrons collide with the surface of the spacer 26 to cause the surface of the spacer 26 to be positive. Charge to potential

In this case, as the focusing electrode 22 forms at least two openings 222 and 223 in the first unit pixels adjacent to the spacer 26, the bridge 224 of the focusing electrode 22 may form the spacer 26. Electrons emitted from the inside of the second opening 223 which are easily attracted toward each other are pushed in a direction opposite to the spacer 26 to suppress electron beam distortion due to charging of the spacer 26.

FIG. 4 is a schematic diagram showing an electron beam spot shape expected in the first unit pixel and second unit pixel configurations shown in FIG. 3.

3 and 4, the electron beam spot BS1 is formed along the shape of the opening 221 of the focusing electrode 22 since there is no electron beam path distortion caused by the spacer 26 in the second unit pixel. In the first unit pixel, the electron beam is attracted toward the spacer 26 due to the charging of the spacer 26, but the bridge 224 pushes the electrons attracted toward the spacer 26 in the opposite direction to the second unit pixel. It is possible to form an electron beam spot BS2 of a substantially similar shape.

FIG. 5 is a partial plan view showing an electron emission display device of a comparative example in which a focusing electrode forms one opening per unit pixel in both the first unit pixel and the second unit pixel, and FIG. 6 is expected in the configuration shown in FIG. 5. It is a schematic diagram which shows the electron beam spot shape.

Referring to the drawing, when the spacer 11 is charged with a positive potential, for example, the electron emission parts 13 positioned at a distance from the first unit pixel to the spacer 11 are surrounded by the focusing electrode and thus emit this electron emission. Electrons emitted from the portion 13 have less drag toward the spacer 11. On the other hand, since the electron emitters 13 'which are far away from the spacer 11 are less affected by the focusing electrode, electrons emitted from the electron emitter 13' are easily attracted toward the spacer 11. In the figure, reference numeral 15 denotes a focusing electrode opening.

Thus, as shown in FIG. 6, the electron beam spot BS4 formed in the first unit pixel is compared with the electron beam spot BS3 formed in the second unit pixel. It causes the display quality to be perceived by the spacer on the screen.

Although the field emission array (FEA) type electron emission display device has been described above, the present invention is not limited to the FEA type, but can be easily applied to other types of electron emission display devices having spacers and focusing electrodes.

In addition, while the preferred embodiment of the present invention has 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. In addition, it is natural that it belongs to the scope of the present invention.

As described above, the electron emission display device according to the present invention can suppress the drag of the electron beam toward the spacer even when the spacer is charged by forming at least two openings in the focusing electrode in the unit pixels adjacent to the spacer. Accordingly, in the electron emission display device according to the present invention, color can be accurately implemented around the spacer, and the display quality can be improved by preventing the spacer from being recognized on the screen.

Claims (8)

A first substrate and a second substrate disposed to face each other; A plurality of electron emission parts provided on the first substrate in a plurality of unit pixels; A focusing electrode positioned on the electron emission parts and forming an opening for passing an electron beam; Fluorescent layers formed on one surface of the second substrate; And Spacers disposed between the first substrate and the second substrate, And at least one unit pixel adjacent to the spacer, the focusing electrode forming a larger number of openings than unit pixels not adjacent to the spacer. The method of claim 1, And the focusing electrode forms one opening per unit pixel in unit pixels not adjacent to the spacer. The method of claim 2, And at least two openings having different distances from the spacer in at least one unit pixel adjacent to the spacer. The method according to claim 2 or 3, An electron emission display device further comprising cathode electrodes formed on the first substrate and electrically connected to the electron emission portions, and gate electrodes formed in a direction intersecting the cathode electrodes while maintaining insulation from the cathode electrodes; . The method of claim 4, wherein And the unit pixels correspond to the intersection regions of the cathode electrodes and the gate electrodes, and the electron emission units are disposed in a line along a length direction of one of the cathode electrode and the gate electrode for each unit pixel. The method of claim 5, The electron emission display device of claim 2, wherein the electron emission units form two rows for each unit pixel, and are arranged in a line along the length direction of the cathode electrode. The method of claim 1, And the electron emission unit comprises at least one material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, C ₆₀ and silicon nanowires. The method of claim 1, And the spacers having a wall shape and spaced apart from each other along a plurality of unit pixels in one direction of the first substrate and another direction perpendicular to the first substrate.

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