KR20070099839A - Electron emission device and electron emission display device using the same - Google Patents

Abstract

An electron emission device and an electron emission display device using the same are provided to realize a high quality image by securing luminance uniformity. An electron emission device includes substrates(2,4), an electron emission unit(12), a cathode electrode(6), a gate electrode(10), and insulating layers(8,14). The electron emission unit is formed on the substrate. The cathode electrode and the gate electrode are formed to control the electron emission unit. The insulating layers are formed between the cathode electrode and the gate electrode. The electron emission device satisfies the following conditions ([Tm-Ti]/Tm)x100 <= 5% where an average thickness of the insulating layers is Tm and a real thickness of the insulating layers is Ti. The insulating layers are formed by using a chemical vapor deposition method or a screen print method.

Description

ELECTRON EMISSION DEVICE AND ELECTRON EMISSION DISPLAY DEVICE USING THE SAME

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

FIG. 2 is a partial cross-sectional view of the electron emission display device shown in FIG. 1. FIG.

3 is a diagram illustrating electron emission uniformity according to an insulation layer thickness distribution of an electron emission display device according to an exemplary embodiment of the present invention.

The present invention relates to an electron emission device and an electron emission display device using the same, and more particularly, to an insulating layer positioned between a cathode electrode and a gate electrode.

In general, an electron emission element 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 a cold cathode is a field emitter array (FEA) type, a surface conduction emission (SCE) type, a metal-insulating layer-metal -Metal (MIM) type and Metal-Insulator-Semiconductor (MIS) type and the like are known.

Among them, the FEA type electron emission device includes an electron emission portion and driving electrodes for controlling electron emission of the electron emission portion and include one cathode electrode and one gate electrode.

The electron emitting portion is a tip structure having a pointed tip structure mainly made of a material having a low work function or a high aspect ratio, such as molybdenum (Mo) or silicon (Si), so that electrons are easily released by an electric field in a vacuum. , Carbon nanotubes and carbon-based materials such as graphite and diamond-like carbon.

On the other hand, the electron emission elements are formed in an array on one substrate to form an electron emission device, and the electron emission device is combined with another substrate having a light emitting unit composed of a fluorescent layer and an anode electrode to emit electrons. A display device (electron emission display device) is constituted.

The electron emission display device has an insulating layer therebetween for insulating the cathode electrode and the gate electrode, which is largely formed by vapor deposition or screen printing.

However, in the vapor deposition method, the pattern thickness varies according to the position of the substrate according to the deposition amount, and in the screen printing method, acid and valleys are formed on the surface of the insulating layer due to the screen mesh, so that the thickness of the insulating layer varies by location. That is, the thickness difference inevitably occurs in each insulating layer.

As described above, when the thickness difference is formed in the insulating layer for each position, the distance between the cathode electrode and the gate electrode and the distance between the electron emission unit and the gate electrode are changed to generate a difference in the potential applied to the electron emission unit for each pixel. Such a difference in potential causes a deterioration in electron emission uniformity between pixels.

However, as described above, it is very difficult to eliminate the thickness difference of the insulating layer. Therefore, rather than eliminating this, it is necessary to obtain an allowable range of the insulation layer thickness distribution capable of ensuring electron emission uniformity, and to manufacture an electron emission device satisfying this allowable range.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide an allowable range of the thickness distribution of the insulating layer that can ensure the uniformity of electron emission, and to provide an electron emission device and an electron emission display device. To provide a reference, and to provide an electron emission device and an electron emission display device that satisfies this.

In order to achieve the above object, an electron emission device according to an embodiment of the present invention includes a substrate, an electron emission portion formed on the substrate, a cathode electrode and a gate electrode for controlling the electron emission portion, and between the cathode electrode and the gate electrode. An insulating layer is formed, and when the average thickness of the insulating layer is Tm, and the actual thickness of each insulating layer is Ti, the following conditions are satisfied.

In addition, the insulating layer may be formed by chemical vapor deposition or screen printing.

In addition, the insulating layer may include silicon oxide (SiO ₂ ).

In addition, the electron emission unit may be formed of at least one material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, fullerenes (C ₆₀ ), and silicon nanowires.

In addition, the electron emitting device according to the embodiment of the present invention can be applied to an electron emitting display device that emits light and displays. Accordingly, the electron emission display device according to the exemplary embodiment of the present invention includes a first substrate and a second substrate disposed to face each other, a cathode electrode formed on the first substrate, an electron emission portion formed on the cathode electrode, and the electron emission. An insulating layer formed on the first substrate and having an opening exposing portions, a gate electrode formed on the insulating layer and having an opening corresponding to the opening, and formed on one surface of the second substrate facing the first substrate And a spacer for maintaining an interval between the first substrate and the second substrate, and an anode electrode formed on one surface of the fluorescent layer.

In addition, the electron emission display device according to the exemplary embodiment of the present invention may further include a focusing electrode having an opening through which the electron beam passes through the gate electrode.

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

Referring to FIGS. 1 and 2, the electron emission display device includes a first substrate 2 and a second substrate 4 that are disposed to face each other in parallel at predetermined intervals. Sealing members (not shown) are disposed at the edges of the first substrate 2 and the second substrate 4 to bond the two substrates, thereby the first substrate 2, the second substrate 4, and the sealing member. Constitutes a vacuum vessel. The interior space of the vacuum vessel is evacuated to a vacuum of approximately 10 ⁻⁶ torr.

On the opposite surface of the first substrate 2 to the second substrate 4, electron emission elements are arranged in an array to form the electron emission device 100 together with the first substrate 2, and the electron emission device ( The 100 is combined with the light emitting unit 110 provided on the first substrate 2 and the second substrate 4 to form an electron emission display device.

More specifically, the cathode electrodes 6 are formed on the first substrate 2 in a stripe pattern along one direction (y-axis direction in FIG. 1) of the first substrate 2, and the cathode electrodes 6 are formed. A covering insulating layer 8 is formed on the entire first substrate 2. Gate electrodes 10 are formed on the insulating layer 8 in a stripe pattern along a direction orthogonal to the cathode electrode 6 (the x-axis direction in FIG. 1).

Here, the insulating layer 8 may be formed by chemical vapor deposition or screen printing. In FIG. 2, the thickness Tm of the insulating layer 8 represents an average thickness, and when taken with an actual scanning electron microscope (SEM), the actual thickness of the insulating layer is formed differently for each position.

An intersection area between the cathode electrode 6 and the gate electrode 10 may form a unit pixel, and electron emission parts 12 are formed in each unit pixel on the cathode electrodes 6. In the insulating layer 8 and the gate electrodes 10, openings 82 and 102 corresponding to the electron emission portions 12 are formed, respectively, to expose the electron emission portions 12 on the first substrate 2. Be sure to

In the drawing, the electron emission parts 12 are formed in a circular shape, and are arranged in a line along the length direction of the cathode electrode 6. However, the planar shape, the number and arrangement per pixel area, etc. of the electron emission unit 12 are not limited to the illustrated example.

In addition, the electron emission unit 12 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. Preferred materials for use as the electron emitter 12 include carbon nanotubes, graphite, graphite nanofibers, diamond, diamond-like carbon, fullerene (C ₆₀ ), silicon nanowires, and combinations thereof.

Meanwhile, the structure in which the gate electrode 10 is positioned above the cathode electrode 6 with the insulating layer 8 interposed therebetween has been described. In the opposite case, that is, the structure in which the gate electrode is positioned below the cathode electrode. It is also possible. In this structure, the electron emission part may be formed on the insulating layer in contact with one side of the cathode electrode.

In addition, the electron emission display device according to the exemplary embodiment may further include a focusing electrode. In the embodiment of the present invention, when the insulating layer 8 positioned between the cathode electrode 6 and the gate electrode 10 is called a first insulating layer, the insulating layer 8 may be formed on the gate electrode 10 and the first insulating layer 8. 2 insulating layers 14 and focusing electrodes 16 are formed, respectively.

In the second insulating layer 14 and the focusing electrode 16, openings 142 and 162 are formed on the first substrate 2 to expose the electron emission portions 12.

One opening 162 of the focusing electrode 16 is formed for each unit pixel so that the focusing electrode 16 comprehensively focuses electrons emitted from one unit pixel or one for each opening 102 of the gate electrode 10. Thus, the electrons emitted from each electron emitter 12 may be individually focused. In the drawings, the former case is illustrated as an example.

Next, on one surface of the second substrate 4 opposite to the first substrate 2, the fluorescent layer 18, for example, the red, green, and blue fluorescent layers 18R, 18G, and 18B may be randomly selected from each other. It is formed at intervals, and a black layer 20 for improving contrast of the screen is formed between each fluorescent layer 18. The fluorescent layer 18 may be disposed such that one fluorescent layer 18 corresponds to each unit pixel set in the first substrate 2.

An anode electrode 22 made of a metal film such as aluminum is formed on the fluorescent layer 18 and the black layer 20. The anode electrode 22 receives an anode voltage necessary for accelerating the electron beam from the outside and increases the brightness of the screen by reflecting the visible light emitted toward the first substrate 2 of the visible light emitted from the fluorescent layer 18. .

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 electrode may be positioned on one surface of the fluorescent layer facing the second substrate and the black layer, and may be formed in plural in a predetermined pattern. The anode electrode may also have a structure in which the above-mentioned transparent conductive film and a metal film are simultaneously formed.

In addition, a plurality of spacers 24 are provided between the first substrate 2 and the second substrate 4 to support the compressive force applied to the vacuum vessel, and to support the first substrate 2 and the second substrate 4. Keep the interval constant. The spacers 24 are disposed corresponding to the non-light emitting regions in which the black layer 20 is located so as not to invade the fluorescent layer 18.

3 is a diagram illustrating electron emission uniformity according to an insulation layer thickness distribution of an electron emission display device according to an exemplary embodiment of the present invention.

In the electron emission display device according to the embodiment of the present invention, the thickness distribution D of the insulating layer 8 is formed to be 5% or less.

The thickness distribution D of the insulating layer 8 is defined as follows when the average thickness of the insulating layer 8 is Tm and the actual thickness for each position of the insulating layer 8 is Ti.

That is, the thickness distribution D of the insulating layer 8 is the absolute value of the difference between the average thickness Tm of the insulating layer 8 and the actual thickness Ti for each position as the average thickness Tm of the insulating layer 8. It is the value formed by dividing and multiplying by 100.

Therefore, when the thickness distribution D of the insulating layer 8 becomes 5% or less, it is as follows.

The small thickness distribution D means that the thickness difference of each position of the insulating layer 8 is small and that the insulating layer 8 is formed evenly. In the embodiment of the present invention, the thickness distribution (D) of the insulating layer 8 The reason why D) should be 5% or less is as follows.

The thickness distribution D of the insulating layer 8 affects the potential applied to the electron emission part 12, and as the thickness distribution D increases, the potential applied to the electron emission part 12 for each pixel is changed. . When the potential of the electron emission unit 12 for each pixel is changed, the electron emission amount of the electron emission unit 2 for each pixel also changes, thereby degrading the electron emission uniformity for each pixel.

The minimum thickness distribution (D) that can secure the electron emission uniformity as described above is 5%.

Referring to FIG. 3, when the thickness distribution D of the insulating layer 8 is 5% or less, the electron emission uniformity is maintained at 95% or more. When the thickness distribution D of the insulating layer 8 exceeds 5%, the electron emission uniformity drops sharply, and as shown in FIG. 3, the electron emission uniformity decreases with a steep slope.

Here, since the electron emission uniformity (%) is proportional to the luminance uniformity, the electron emission uniformity in FIG. 3 was obtained as the luminance uniformity between adjacent pixels. Luminance uniformity is obtained by dividing the minimum luminance value by the maximum luminance value and multiplying it by 100.

In the case of chemical vapor deposition, the thickness of the insulating layer 8 may be adjusted by temperature, power, gas amount, and the like. In the case of screen printing, the thickness of the insulating layer 8 may be adjusted by the wire diameter of the screen mesh, the number of meshes, and the like. Can be.

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, the present invention provides an electron emission device capable of securing electron emission uniformity for each pixel by providing a range for the thickness distribution of the insulating layer. Accordingly, the electron emission display device according to the exemplary embodiment of the present invention can secure high-quality images by ensuring luminance uniformity.

Claims (6)

Board; An electron emission unit formed on the substrate; A cathode electrode and a gate electrode controlling the electron emission unit; And An insulating layer formed between the cathode electrode and the gate electrode Including; An electron emitting device that satisfies the following conditions when the average thickness of the insulating layer is Tm and the actual thickness of each of the insulating layers is Ti.

The method of claim 1, And the insulating layer is formed by chemical vapor deposition or screen printing. The method of claim 1, And the insulating layer comprises silicon oxide (SiO ₂ ). The method of claim 1, And the electron emission unit is formed of at least one material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, fullerenes (C ₆₀ ), and silicon nanowires. A first substrate and a second substrate disposed to face each other; A cathode electrode formed on the first substrate; An electron emission unit formed on the cathode electrode; An insulating layer formed on the first substrate and having an opening exposing the electron emission portion; A gate electrode formed on the insulating layer and having an opening corresponding to the opening; A fluorescent layer formed on one surface of the second substrate facing the first substrate; An anode formed on one surface of the fluorescent layer; And Spacer to maintain the gap between the first substrate and the second substrate Including; And assuming that the average thickness of the insulating layer is Tm and the actual thickness of each of the insulating layers is Ti, the following condition is satisfied.

The method of claim 5, And a focusing electrode having an opening through which the electron beam passes through the gate electrode.

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