KR100796691B1 - Light emission device and liquid crsytal display using the light emission device as back light unit - Google Patents

Abstract

A light emitting device and a liquid crystal display device using the light emitting device as a backlight unit are provided to improve an effective region of the light emitting device by forming a getter film in a sealing member. First and second substrates(12,14) are arranged to be opposite to each other. An effective region is defined on the first and second substrates. A sealing member(16) is arranged at an edge portion of the substrates and forms a vacuum container with the first and second substrates. An electron emitting unit(18) is provided on the first substrate. A light emitting unit(20) is provided on the second substrate and emits light according to the electrons which are emitted from the electron emitting unit. A getter(21) is arranged between the first and second substrates at an edge of the effective region. The getter includes a getter member, a getter container, and a support member which is fixed on the first and second substrates and supports the getter container.

Description

LIGHT EMISSION DEVICE AND LIQUID CRSYTAL DISPLAY USING THE LIGHT EMISSION DEVICE AS BACK LIGHT UNIT}

1 is a partially exploded perspective view of a light emitting device according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of the getter shown in FIG. 1. FIG.

3 is a partial cross-sectional view of a light emitting device according to an embodiment of the present invention.

4 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

The present invention relates to a light emitting device and a liquid crystal display device employing the same as a backlight unit, and more particularly, to a getter.

Recently, a liquid crystal display device, which is a type of flat panel display device, has been widely used to replace a cathode ray tube. The liquid crystal display device has a feature of changing light transmittance for each pixel by using dielectric anisotropy of a liquid crystal whose twist angle changes according to an applied voltage. .

Such a liquid crystal display device is a representative non-luminescent display for displaying an image with the help of an external light source, and basically includes a liquid crystal panel assembly and a backlight unit for providing light to the liquid crystal panel assembly, wherein the liquid crystal panel assembly is used in the backlight unit. By receiving the emitted light, the light is transmitted or blocked by the action of the liquid crystal layer to realize a predetermined image.

The backlight unit may be classified according to the type of light source, and one of them is a cold cathode fluorescent lamp (CCFL) method, which is known as a CCFL. It can be evenly dispersed toward the liquid crystal panel assembly through an optical member such as a diffusion sheet and a diffusion plate and a prism sheet.

However, in the CCFL method, since the light generated by the CCFL passes through the optical member, a considerable light loss occurs, and in consideration of the optical loss, the CCFL method requires a large intensity of light to emit a high power consumption. Due to the difficulty in large area, it is difficult to apply to large display devices of 30 inches or more.

In addition, a light emitting diode (LED) method is known as a conventional backlight unit. LEDs are generally provided as a plurality of point light sources, and include a reflective sheet, a light guide plate, a diffusion sheet, a diffusion plate, and a prism. The LED unit is combined with an optical member such as a sheet to construct a backlight unit. The LED method has advantages of fast response speed and excellent color reproducibility, but has a disadvantage of high price and large thickness.

Accordingly, recently, a field emission type backlight unit that emits light using an electron emission characteristic by an electric field has been proposed as a backlight unit to replace the CCFL method and the LED method.

Conventional field emission type backlight unit includes a getter for increasing the degree of vacuum inside the vacuum vessel. The getter is a chemical vacuum pump made of a material capable of reacting with gas molecules. The activated getter chemically adsorbs the residual gases in the vacuum vessel to increase the degree of vacuum. These getters are classified into evaporation type and non-evaporation type.

However, a conventional evaporation getter forms a getter film which is flashed and then deposited inside the vacuum vessel, which is usually formed outside the effective area of the first substrate or the second substrate constituting the vacuum vessel. This is to deposit sufficient area inside the vacuum vessel to sufficiently adsorb residual gases.

However, if the getter film is formed outside the effective regions of the first substrate and the second substrate in this way, there is a problem that the dead space of the substrate for getter film deposition increases by that much.

In addition, since the conventional backlight unit is always turned on at a constant brightness while driving the display device, there is a problem that it is difficult to meet the image quality improvement required for the display device.

For example, when the liquid crystal panel assembly displays an arbitrary screen including a bright portion and a dark portion according to an image signal, the backlight unit provides light of different intensities in the region displaying the bright portion and the region displaying the dark portion. If so, it is possible to realize a screen having excellent dynamic contrast.

However, the above-described backlight unit cannot implement the above functions, and thus the conventional liquid crystal display device has a limitation in increasing the dynamic contrast ratio of the screen.

Accordingly, an object of the present invention is to provide a light emitting device capable of minimizing an invalid area of a substrate for installing a getter and a liquid crystal display using the light emitting device as a backlight unit. .

Another object of the present invention is to provide a light emitting device capable of dividing a light emitting surface into a plurality of regions and independently controlling the light intensity of each divided region, and a liquid crystal display capable of increasing the dynamic contrast ratio of a screen by using the light emitting apparatus as a backlight unit. To provide a device.

In order to achieve the above object, the present invention is directed to a first substrate and a second substrate disposed opposite to each other and the effective area is set, the first substrate and the second substrate located at the edge of the first substrate and the second substrate And a sealing member constituting a vacuum container, an electron emission unit provided on the first substrate, a light emitting unit provided on the second substrate, and emitting light by electrons emitted from the electron emission unit, and outside the effective area. And a getter provided between the first substrate and the second substrate, wherein the getter has a getter material, an opener facing the sealing member, the getter container in which the getter material is stored, and the first and second substrates. Each of which is fixed and includes a support for supporting the getter container.

In addition, the support may include a linear first support connected to one side of the getter container and fixed to the first substrate, and a linear second support connected to the other side of the getter container and fixed to the second substrate. have.

In addition, the first support and the second support may be drawn out of the vacuum container while crossing the sealing member.

The getter vessel, the first support and the second support may be made of a conductive material, and the getter material may be activated by a current flowing along the first support, the getter vessel, and the second support.

In addition, the getter material is barium (Ba), titanium (Ti), vanadium (V), zirconium (Zr), niobium (Nb), molybdenum (Mo), tantalum (Ta), barium-aluminum (Ba-Al), zirconium It may include any one material selected from the group consisting of aluminum (Zr-Al), silver-titanium (Ag-Ti) and zirconium-nickel (Zr-Ni).

In addition, the distance between the first substrate and the second substrate may be in the range of 5 to 20 mm.

In addition, the electron emission unit may be electrically connected to one of the first and second electrodes and any one of the first and second electrodes formed along an intersecting direction while maintaining an insulation state. It may include an electron emitter.

In addition, the present invention provides a liquid crystal display including a light emitting device and a liquid crystal panel assembly positioned in front of the light emitting device to receive light emitted from the light emitting device to display an image.

In addition, the liquid crystal panel assembly may have first pixels, and the light emitting device may have a smaller number of second pixels than the first pixels, and emit light having different intensities for each of the second pixels.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. However, the present invention may be embodied in many different forms. In the drawings, parts that are not related to the description are omitted for clarity of explanation, and like reference numerals designate like elements throughout the specification.

1 is a partially exploded perspective view of a light emitting device according to an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of the getter shown in FIG. 1.

Referring to FIG. 1, the light emitting device 10 according to the present exemplary embodiment includes a first substrate 12 and a second substrate 14 that are disposed to face each other in parallel at predetermined intervals. The sealing member 16 is disposed at the edge of the substrate 14 to bond the two substrates together, and the inner space is evacuated to a vacuum of approximately 10 ⁻⁶ Torr so that the first substrate 12 and the second substrate 14 and the sealing member are disposed. 16 constitutes a vacuum container.

The first substrate 12 and the second substrate 14 are partitioned into an effective region contributing to the actual visible light emission inside the sealing member 16 and an ineffective region surrounding the effective region. The region is provided with an electron emitting unit 18 for electron emission, and the effective region of the second substrate 14 is provided with a light emitting unit 20 for emitting visible light.

In addition, a getter 21 is installed and activated in an ineffective region between the first substrate 12 and the second substrate 14 to adsorb gases remaining in the vacuum vessel.

Referring to FIG. 2, the getter 21 includes a getter material 211, a getter container 212, a first support 213, and a second support 214.

In the case of an evaporative getter, the getter material 211 is made of metals such as barium (Ba), titanium (Ti), vanadium (V), zirconium (Zr), niobium (Nb), molybdenum (Mo), and tantalum (Ta). , Barium-aluminum (Ba-Al), zirconium-aluminum (Zr-Al), silver-titanium (Ag-Ti), zirconium-nickel (Zr-Ni) and the like.

The getter container 212 holds the getter material 211 and is formed in a flat cylindrical shape having an opening on one side. The getter container 212 is disposed so that the opening faces the sealing member 16. This is to cause the getter material 211 stored in the 212 to be deposited on the sealing member 16 when flashed.

The shape of the getter container 212 can be modified in various ways, such as a flat cylindrical, flat square.

The getter container 212 is fixed between the first substrate 12 and the second substrate 14 by a support. The support body is connected to one side of the getter container 212 and is fixed to the first substrate 12. And a first support 214 connected to the other side of the getter container 212 and fixed to the second substrate 14. The getter container 212 is formed by the first and second supporters 213 and 214. ) May float between the first substrate 12 and the second substrate 14.

The first and second supports 213 and 214 may be formed in a linear manner, and each of the first and second supports 213 and 214 extends outside the sealing member 16 to be firmly fixed to the first and second substrates 12 and 14, respectively. The second supports 213 and 214 may be drawn out of the vacuum vessel while crossing the sealing member 16. As such, the first and second supports 213 and 214 may be drawn out of the vacuum vessel. The reason is to apply a current to the first and second supports 213 and 214 so that the getter material 211 can be flashed, so that the getter container 212 and the first and second supports ( 213 and 214 may be made of a conductive material such as metal.

Each of the getters 21 may be arranged in plural numbers at predetermined intervals along each side of the sealing member 16.

3 is a partial cross-sectional view of a light emitting device according to an embodiment of the present invention and shows a specific configuration of an electron emission unit and a light emitting unit.

Referring to FIG. 3, the electron emission unit 18 may include first and second electrodes 22 and 26 formed in a stripe pattern in a direction crossing each other with the insulating layer 24 interposed therebetween, And electron emission portions 28 electrically connected to either one of the first electrode 22 and the second electrode 26.

When the electron emission portion 28 is formed on the first electrode 22, the first electrode 22 becomes a cathode electrode for supplying current to the electron emission portion 28, and the second electrode 26 is a cathode electrode. When the electron emission portion 28 is formed in the second electrode 26, the second electrode 26 becomes a cathode electrode, forming an electric field by the voltage difference between The first electrode 22 becomes a gate electrode.

An electrode positioned along the row direction (x-axis direction in FIG. 3) of the light emitting device 10 among the first electrode 22 and the second electrode 26 functions as a scan electrode, and the column direction of the light emitting device 10 is used. The electrodes located along the side function as data electrodes.

Openings 261 and 241 are formed in the second electrode 26 and the insulating layer 24 at each intersection of the first electrode 22 and the second electrode 26 to expose a part of the surface of the first electrode 22. The electron emission part 28 is positioned on the first electrode 22 inside the opening 241 of the insulating layer 24.

The electron emission unit 28 is a kind of electron emission layer having a predetermined thickness and diameter, and may be formed of materials emitting electrons when a electric field is applied in vacuum, such as a carbon-based material or a nanometer-sized material.

The electron emission unit 28 may include, for example, carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, fullerenes (C ₆₀ ), silicon nanowires, or a combination thereof, and may be screen printed by the method. Direct growth, chemical vapor deposition or sputtering.

The electron emitters 28 are gathered and positioned in the middle portion of the intersection region of the first electrode 22 and the second electrode 26 except for an edge in consideration of electron beam spreading characteristics.

In the above structure, one intersection area of the first electrode 22 and the second electrode 26 corresponds to one pixel area of the light emitting device 10, or two or more crossing areas are one pixel area of the light emitting device 10. In the second case, two or more first electrodes 22 or two or more second electrodes 26 corresponding to one pixel area may be electrically connected to each other to receive the same driving voltage.

Next, the light emitting unit 20 includes a fluorescent layer 30 and an anode electrode 32 positioned on one surface of the fluorescent layer 30. The fluorescent layer 30 may be formed of a white fluorescent layer, or may be red and green. And blue fluorescent layers may be configured in combination. FIG. 1 illustrates a first case.

The white fluorescent layer may be formed in the entirety of the second substrate 14 or may be divided and disposed in a predetermined pattern such that one white fluorescent layer is positioned in each pixel area. The red, green, and blue fluorescent layers may be predetermined in one pixel area. It can be separated by the pattern of.

The anode electrode 32 may be formed of a metal film such as aluminum (Al) covering the surface of the fluorescent layer 30. The anode electrode 32 is an acceleration electrode for attracting an electron beam and is applied with a high voltage to pass the fluorescent layer 30. While maintaining the above state, the visible light emitted from the fluorescent layer 30 is reflected toward the first substrate 12 to the second substrate 14 to increase the brightness of the screen.

Spacers 34 may be disposed between the first substrate 12 and the second substrate 14 to support the compressive force applied to the vacuum container and to maintain a constant gap between the two substrates. The spacer 34 may be positioned outside the cross region of the second electrode 26 and the second electrode 26. For example, the spacer 34 may be made of glass or ceramic.

The light emitting device 10 having the above-described configuration applies a predetermined driving voltage to the first electrodes 22 and the second electrodes 26 from the outside of the vacuum container, and the direct current amount of thousands of volts or more to the anode electrode 32. Drive by applying voltage.

Then, in the pixels where the voltage difference between the first electrode 22 and the second electrode 26 is greater than or equal to the threshold, an electric field is formed around the electron emission unit 28 to emit electrons therefrom, and the emitted electrons are attracted to the anode voltage to correspond. The light emission intensity of the fluorescent layer 30 for each pixel corresponds to the electron beam emission amount of the corresponding pixel.

The light emitting device of the above-described embodiment applies a high voltage of 10 kV or more, preferably 10 to 15 kV, to the anode electrode 32 through the anode pad portion so as to achieve a maximum brightness of approximately 10,000 cd / m ² or more in the center of the effective region. In the light emitting device of the present embodiment, the distance between the first substrate 12 and the second substrate 14 is kept large in the range of 5 to 20 mm in order to eliminate electrical instability such as a short in the vacuum container due to the application of a high voltage.

As the distance between the first substrate 12 and the second substrate 14 increases, the height of the sealing member 16 is increased, and the area of the entire inner surface of the sealing member 16 is also increased. As a result, the sealing member 16 provides sufficient space for the getter film to be deposited. As a result, the getter is flashed toward the sealing member 16 (arrow in FIG. 3) so that the getter film is formed on the inner surface of the sealing member 16. Even in this case, the getter film can adsorb residual gas in the vacuum container due to the sufficient area.

Therefore, the light emitting device according to the embodiment of the present invention does not need to form the getter film on the first and second substrates 12 and 14, and thus does not require a separate dead space for depositing it. .

4 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the liquid crystal display device 50 according to the present exemplary embodiment includes a liquid crystal panel assembly 52 forming a plurality of pixels in a row direction and a column direction, and is located behind the liquid crystal panel assembly 52 to form a liquid crystal panel assembly. And a light emitting device 10 that provides light to 52. Hereinafter, for convenience, the light emitting device will be referred to as a backlight unit.

Any known liquid crystal panel assembly may be applied to the liquid crystal panel assembly 50, and an optical member such as a diffusion plate or a diffusion sheet may be disposed between the liquid crystal panel assembly 52 and the light emitting device 10 as necessary.

In the present exemplary embodiment, the backlight unit 10 forms a smaller number of pixels than the liquid crystal panel assembly 52 along the row direction and the column direction so that one pixel of the backlight unit 10 includes a plurality of pixels of the liquid crystal panel assembly 52. Each pixel of the backlight unit 10 may emit light corresponding to the highest gray level among the pixels of the liquid crystal panel assembly 52 corresponding thereto, and the backlight unit 10 may have 2 to 8 bits for each pixel. You can express the gradation of.

For convenience, a pixel of the liquid crystal panel assembly 52 is called a first pixel, a pixel of the backlight unit 10 is called a second pixel, and a plurality of first pixels corresponding to one second pixel is called a first pixel group. do.

In the above-described driving of the backlight unit 10, the signal controller 54 controlling the liquid crystal panel assembly 52 detects the highest gray level among the first pixels of the first pixel group, and according to the detected gray level, the second pixel. Calculating the grayscale required for light emission and converting it into digital data, and generating a driving signal of the backlight unit 10 using the digital data, the second pixel of the backlight unit 10 When an image is displayed in the first pixel group, light may be emitted at a predetermined gray level in synchronization with the first pixel group.

The row direction may be defined as one direction of the liquid crystal display 50, for example, a horizontal direction (x-axis direction of the drawing) of the screen implemented by the liquid crystal panel assembly 52, and the column direction may be defined as the liquid crystal display 50. ) May be defined as a vertical direction (y-axis direction of the drawing) of the screen implemented by the liquid crystal panel assembly 52.

The liquid crystal panel assembly 52 may form 240 or more pixels along the row direction and the column direction, and the backlight unit 10 may form 2 to 99 pixels along the row direction and the column direction. And when the number of pixels of the backlight unit 10 in the column direction exceeds 99, driving of the backlight unit 10 may be complicated and may cause an increase in cost for manufacturing a driving circuit.

As such, the backlight unit 10 is a kind of self-luminous display panel having a resolution of 2 × 2 to 99 × 99. The backlight unit 10 controls the light emission intensity independently for each pixel to be suitable for the pixels of the liquid crystal panel assembly 52 corresponding to each pixel. Therefore, the liquid crystal display device 50 according to the present embodiment can increase the dynamic contrast of the screen and can realize a clearer picture quality.

In the light emitting device according to the present invention, by forming the getter film on the sealing member, the effective area of the light emitting device can be reduced, and the getter container can be more firmly fixed by a support fixed to both sides of the first substrate and the second substrate.

In addition, the liquid crystal display device using the above-described light emitting device as a backlight unit can improve the display quality by increasing the contrast of the screen and the dynamic contrast ratio of the screen, and can reduce the total power consumption by reducing the power consumption of the backlight unit, and is 30 inches or more. It can be easily manufactured in a large display device.

Claims (9)

A first substrate and a second substrate disposed to face each other and having an effective area set therein; A sealing member positioned at an edge of the first substrate and the second substrate to form a vacuum container together with the first substrate and the second substrate; An electron emission unit provided on the first substrate; A light emitting unit provided on the second substrate and emitting light by electrons emitted from the electron emitting unit; And A getter provided between the first substrate and the second substrate outside the effective area; Including; And the getter includes a getter material, an getter container having an opening facing the sealing member, and a support for holding the getter material and being fixed to the first and second substrates, respectively. The method of claim 1, The support, And a linear first support connected to one side of the getter container and fixed to the first substrate, and a linear second support connected to the other side of the getter container and fixed to the second substrate. The method of claim 2, And the first and second supports are led out of the vacuum container while crossing the sealing member. The method of claim 3, The getter container, the first support and the second support are made of a conductive material, The getter material is activated by a current flowing along the first support, the getter container and the second support. The method of claim 1, The getter material is barium (Ba), titanium (Ti), vanadium (V), zirconium (Zr), niobium (Nb), molybdenum (Mo), tantalum (Ta), barium-aluminum (Ba-Al), zirconium-aluminum A light emitting device comprising any one material selected from the group consisting of (Zr-Al), silver-titanium (Ag-Ti) and zirconium-nickel (Zr-Ni). The method of claim 1, The light emitting device having a distance between the first substrate and the second substrate in a range of 5 to 20 mm. The method of claim 6, The electron emission unit, First and second electrodes formed along an intersecting direction while maintaining an insulated state; And And an electron emission unit electrically connected to any one of the first electrodes and the second electrodes. The light emitting device according to any one of claims 1 to 7; And A liquid crystal panel assembly positioned in front of the light emitting device to receive light emitted from the light emitting device to display an image Liquid crystal display comprising a. The method of claim 8, The liquid crystal panel assembly has first pixels, The light emitting device has a smaller number of second pixels than the first pixels, and the second pixels provide light to the liquid crystal panel assembly by independently controlling emission intensity for each pixel.

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