KR20070117335A - Light emission device and liquid crystal display device using the same as back light unit - Google Patents

Abstract

A light emitting device and an LCD(Liquid Crystal Display) using the same as a backlight unit are provided to emit heat of an effective area region without blocking light by installing a patterned heat emitting plate between a second substrate and a diffusion plate, and sufficiently disperse the light as ensuring a distance between the second substrate and the diffusion plate. First and second substrates(12,14) face each other. An electron emission unit(110) is provided within the first substrate. A fluorescent layer is formed within the second substrate, and emits light by electrons emitted from the electron emission unit. An anode electrode is formed in a side of the fluorescent layer. A spacer(18) maintains a gap between the first and second substrates. A diffusion plate(20) is formed on the second substrate and diffuses light emitted from the fluorescent layer. A heat emitting plate(22) is formed between the second substrate and the diffusion plate.

Description

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

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

FIG. 2 is a partial cross-sectional view of the light emitting device shown in FIG. 1.

3 and 4 are views showing a pattern of the heat sink.

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

6 is a partial cross-sectional view of the light emitting device shown in FIG. 5.

7 is an exploded perspective view of a liquid crystal display device using a light emitting device as a backlight unit.

FIG. 8 is a partial cutaway perspective view of the liquid crystal panel assembly shown in FIG. 7.

9 is a block diagram of a configuration for driving a liquid crystal display device.

The present invention relates to a light emitting device and a liquid crystal display using the same as a backlight unit, and more particularly, to a heat dissipation structure of a light emitting device.

Recently, a liquid crystal display device, which is a type of flat panel display device, has been widely used in place of a cathode ray tube. The liquid crystal display has a characteristic of changing the amount of light transmission for each pixel by using the dielectric anisotropy of the liquid crystal whose twist angle changes according to the applied voltage.

Such a liquid crystal display device basically includes a liquid crystal panel assembly and a backlight unit positioned at the rear of the liquid crystal panel assembly to provide light to the liquid crystal panel assembly. The liquid crystal panel assembly receives light emitted from the backlight unit and transmits or blocks the light 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). Since the CCFL is a line light source, the light generated from the CCFL can be evenly distributed toward the liquid crystal panel assembly through optical members such as a diffusion sheet, a diffusion plate, and a prism sheet.

However, in the CCFL method, since the light generated by the CCFL passes through the optical member, considerable light loss occurs, and power consumption is high because the light must be emitted at a high intensity from the CCFL in consideration of the light loss. In addition, the CCFL method is difficult to apply to a large liquid crystal display device of 30 inches or more because it is difficult to large area structure.

As a conventional backlight unit, a light emitting diode (LED) method is known. LEDs are usually provided in plural as point light sources, and constitute a backlight unit by being combined with optical members such as a reflective sheet, a light guide plate, a diffusion sheet, a diffusion plate, and a prism sheet. This LED method has the advantages of fast response speed and excellent color reproducibility, but has a disadvantage of high price and large thickness.

As such, the conventional backlight unit has respective problems according to the type of light source. In addition, since the conventional backlight unit is always turned on at a constant brightness when the liquid crystal display is driven, it is difficult to meet the image quality improvement required for the liquid crystal display.

For example, when the liquid crystal panel assembly displays an arbitrary screen including a bright portion and a dark portion in accordance with an image signal, the backlight unit displays the liquid crystal panel pixels portion displaying the bright portion and the liquid crystal panel pixels displaying the dark portion. If the light of different intensity is provided to the part, 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.

On the other hand, a field emission display (FED, hereinafter referred to as 'FED') that displays by using an electron emission characteristic by an electric field is known, and the FED is used as a backlight unit of a liquid crystal display device. R & D is underway.

The FED is basically provided on one side of the second substrate, an electron emission unit including an electron emission section and driving electrodes, provided on one side of a vacuum container composed of a first substrate, a second substrate, and a sealing member. The light emitting unit includes a fluorescent layer and an anode electrode.

The electron emission unit emits electrons for each pixel according to a driving signal applied to the driving electrodes, and the anode electrode receives a direct current voltage of thousands of volts to accelerate the electrons to the fluorescent layer, and the accelerated electrons are the fluorescent layer of the corresponding pixel. Emit light.

In order to use the FED as a backlight unit, it is necessary to increase the luminance of the screen by applying a higher amount of voltage to the anode electrode than when using the display device. The backlight unit usually requires a high brightness of 10,000 cd / m 2 or more, so when the FED is used as a backlight unit, the FED generates a lot of heat. If the heat is continuously accumulated in the FED without dissipating such heat, serious problems in driving as well as structural problems such as cracking of the substrate occur.

In addition, since light must be transmitted to the side of the substrate where the anode electrode and the fluorescent layer are located, it is very difficult to provide a structure capable of emitting heat in this portion.

Therefore, the present invention is to solve the above problems, an object of the present invention is to provide a light emitting device that can be used as a backlight unit by improving the heat dissipation efficiency while ensuring the transmission of light emitted from the fluorescent layer.

In addition, another object of the present invention is to provide a liquid crystal display device which can implement excellent screen quality by increasing the dynamic contrast ratio of the screen by employing the light emitting device as a backlight unit.

In order to achieve the above object, a light emitting device according to an embodiment of the present invention is formed on an inner surface of the first substrate and the second substrate, the electron emission unit provided on the inner surface of the first substrate, the second substrate disposed opposite to each other And a fluorescent layer emitting light by electrons emitted from the electron emission unit, an anode formed on one surface of the fluorescent layer, a spacer to maintain a gap between the first substrate and the second substrate, and a second substrate formed on the second substrate. And a diffuser plate for dispersing light emitted from the fluorescent layer, and a heat sink formed between the second substrate and the diffuser plate, wherein the second substrate is positioned outside the effective area where the actual light is emitted and the effective area. The heat dissipation plate may be divided into an ineffective area, and the heat sink may be patterned to allow light emitted from the fluorescent layer to pass through the effective area.

The heat dissipation plate may include a hole through which light emitted from the fluorescent layer passes and a hole through which light emitted from the fluorescent layer is blocked, and an area occupied by the hole in the effective area may be S1 within the effective area. When the area occupied by the no void is S2, the light emitting device may satisfy the following conditions.

1 ≤ S1 / S2 ≤ 19

In addition, the hole may be formed to have a predetermined pitch in the effective area. In this case, the hole may be formed corresponding to each pixel.

The heat sink may be formed in a linear or mesh shape.

In addition, the heat sink may include at least one material selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), and platinum (Pt).

In addition, the heat sink may have a thickness within the range of 0.05 ~ 10 mm.

In addition, the heat dissipation plate may be formed by depositing a metal material on the second substrate and then patterning the metal plate.

The electron emission unit may include a cathode electrode, a gate electrode, and an electron emission portion connected to the cathode electrode, which are formed along an intersecting direction with an insulating layer therebetween.

In addition, the electron emission unit may include at least one of a carbon-based material and a nanometer size material.

In addition, the light emitting device according to the embodiment of the present invention can be used in the liquid crystal display as a backlight unit. Accordingly, the liquid crystal display according to the exemplary embodiment of the present invention includes a liquid crystal panel assembly having a plurality of pixels in a row direction and a column direction, and the light emitting device positioned behind the liquid crystal panel to function as a backlight unit. .

In addition, the light emitting device may have a smaller number of pixels than the liquid crystal panel assembly in the row direction and the column direction, and may emit light of different intensity for each pixel.

In addition, the light emitting device may express a gray level of 2 to 8 bits for each pixel.

In addition, the fluorescent layer may be formed of a white fluorescent layer, or may be formed of a red, green, and blue fluorescent layer.

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

1 is an exploded perspective view of a light emitting device according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view of the light emitting device shown in FIG. 1, and FIGS. 3 and 4 are views illustrating patterns of a heat sink.

1 and 2, the light emitting device 100 includes a first substrate 12 and a second substrate 14 disposed to face each other at a predetermined interval. The sealing member 16 is disposed at the edge of the first substrate 12 and the second substrate 14 to bond the two substrates, and thus the first substrate 12, the second substrate 14, and the sealing member 16. ) Constitutes a vacuum vessel. The inner space of the vacuum vessel is evacuated to a vacuum of approximately 10 ⁻⁶ Torr.

The electron emission unit 110 is disposed on the inner surface of the first substrate 12 of the vacuum vessel, and the light emitting unit 120 is disposed on the inner surface of the second substrate 14 of the vacuum vessel. Spacers 18 are disposed between the light emitting units 120 to maintain a gap between the first substrate 12 and the second substrate 14.

A diffusion plate 20 for dispersing light emitted from the light emitting unit 120 is formed on the second substrate 14, and the light emitting unit 120 is disposed between the second substrate 14 and the diffusion plate 20. Heat dissipation plate 22 for dissipating heat to the outside is formed.

The second substrate 14 may be divided into an effective area A in which light is actually emitted and an invalid area NA located at an outer side of the effective area A. The heat sink 22 may be formed of the effective area A. ) And may have a predetermined pattern. That is, the heat sink 22 is patterned to allow the light emitted by the light emitting unit 120 to pass through.

For example, the heat dissipation plate 22 may include a hole 221 through which light emitted from the light emitting unit 120 passes and a hole 222 through which light emitted from the light emitting unit 120 is blocked. The hole 221 may be disposed in the effective area A with a predetermined pitch along one direction.

The perforations 221 may be formed in an irregular arrangement as well as in a regular arrangement. When the perforations 221 are regularly arranged, they may be formed corresponding to pixels. That is, when the fluorescent layer to be described later is formed corresponding to each pixel, the hole 221 may be formed corresponding to the fluorescent layer. In contrast, when the black layer is formed in the light emitting device, the non-porous portion 222 may be positioned corresponding to the black layer.

In addition, when the area occupied by the perforations 221 in the effective area A is S1 and the area occupied by the non-perforations 222 in the effective area A is S2, the perforations for the non-perforations 222 are defined. The area ratio S1 / S2 of 221 may satisfy the following condition.

1 ≤ S1 / S2 ≤ 19

The area ratio 1 means 50% of the aperture ratio (percentage of the perforated area to the effective area area), and the area ratio 19 means 95% of the aperture ratio.

If the area ratio is less than 1, the luminance of the light emitting device is reduced. If the area ratio is more than 19, the heat dissipation efficiency is reduced.

In this embodiment, even if the opaque heat sink 22 is disposed in the effective area A, the light emitted from the light emitting unit 120 may pass through the heat sink 22 through the hole 221. Therefore, the light emitting device according to the embodiment of the present invention can perform a heat dissipation function while maintaining a light emitting function.

In addition, in the light emitting device according to the embodiment of the present invention, a predetermined gap G is secured between the second substrate 14 and the diffusion plate 20 to eliminate a phenomenon in which the luminance difference occurs around the spacer 18. can do.

In order to secure the gap G as described above, the heat sink 22 may have a thickness t in the range of 0.05 to 10 mm. If the thickness is less than 0.05 mm, the heat dissipation efficiency is lowered. If the thickness is more than 10 mm, the distance from the diffuser plate 20 is farther away, resulting in a decrease in luminance of the light emitting device.

In addition, the heat dissipation plate 22 may be made of a metal or an alloy having a high thermal conductivity so as to efficiently discharge heat generated from the light emitting device. For example, the heat sink 22 may be made of aluminum (Al), silver (Ag), copper (Cu), platinum (Pt), or a combination thereof.

Referring to FIGS. 3 and 4, the heat sinks P1 and P2 may be, for example, linearly formed side by side in one direction of the substrate, or may be formed in a mesh shape in which a plurality of heat sinks are arranged in a direction crossing each other. The pattern of the heat sink is not limited thereto, and various modifications may be made to the shape of the heat sink if the structure allows light to pass therethrough. 3 and 4, dotted lines indicate pixels.

The heat dissipation plate 22 may be manufactured by depositing a metal material on the second substrate 14 and then patterning the same, or between the second substrate 14 and the diffusion plate 20 by manufacturing a preformed metal plate. Can be inserted.

5 is a partial cutaway perspective view of a light emitting device according to an embodiment of the present invention, and FIG. 6 is a partial cross-sectional view of the light emitting device shown in FIG. 5.

The light emitting device 100 includes an electron emitting unit consisting of an electron emitting device, which may be classified into a method using a hot cathode and a cold cathode according to the type of electron source. Can be.

Here, as an electron emission device using a cold cathode, it is referred to as a field emitter array (FEA) type, surface-conduction emission (SCE). ), Metal-insulator-metal (MIM) type and metal-insulator-semiconductor (MIS) type There is this.

The light emitting device 100 according to the embodiment of the present invention includes, for example, an electron emission unit made of an FEA type electron emission device.

5 and 6, the electron emission unit 110 includes cathode electrodes 24 formed in a stripe pattern along one direction (y-axis direction in FIG. 3) of the first substrate 12, and an insulating layer. Gate electrodes 28 formed in a stripe pattern along a direction orthogonal to the cathode electrode 24 (the x-axis direction in FIG. 3) with the interposed between the electrodes 26 and the electrons electrically connected to the cathode electrode 24. Discharge portions 30.

The gate electrodes 28 may receive a scan signal to function as scan electrodes, and the cathode electrodes 24 may receive a data signal to serve as data electrodes.

Electron emitters 30 are formed in the cathode electrode 24 at each intersection region of the cathode electrode 24 and the gate electrode 28. Openings 261 and 281 corresponding to each electron emission part 30 are formed in the insulating layer 26 and the gate electrodes 28 so that the electron emission part 30 is exposed on the first substrate 12. do.

In the above-described structure, one intersection region of the cathode electrode 24 and the gate electrode 28 may correspond to one pixel region of the light emitting device, or two or more intersection regions may correspond to one pixel region of the light emitting device. In the second case, two or more cathode electrodes 24 and two or more gate electrodes 28 corresponding to one pixel area may be electrically connected to each other to receive the same driving voltage.

The electron emission part 30 is 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 30 may include, for example, carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, fullerenes (C ₆₀ ), silicon nanowires, or a combination thereof. The electron emitting portion 30 may be manufactured by screen printing, direct growth, chemical vapor deposition, or sputtering.

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).

Next, the light emitting unit 120 provided on the second substrate 14 includes a fluorescent layer 32 and an anode electrode 34 positioned on one surface of the fluorescent layer 32. The fluorescent layer 32 may be formed of a white fluorescent layer or a combination of red, green, and blue fluorescent layers. In the figure, the first case is illustrated.

The white fluorescent layer may be formed on the entirety of the second substrate 14, or may be divided and positioned 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 divided and positioned in a predetermined pattern in one pixel area.

The anode electrode 34 may be formed of a metal film such as aluminum (Al) covering the surface of the fluorescent layer 32. The anode electrode 34 is an acceleration electrode for attracting an electron beam, and is applied with a high voltage (a positive DC voltage of approximately several thousand volts) to maintain the fluorescent layer 32 in a high potential state, and among the visible light emitted from the fluorescent layer 32. The luminance of the screen is increased by reflecting the visible light emitted toward the first substrate 12 toward the second substrate 14.

When a predetermined driving voltage is applied to the cathode electrodes 24 and the gate electrodes 28 in the above-described configuration, an electric field is formed around the electron emission section 30 in the pixel region where the voltage difference between the two electrodes is greater than or equal to the threshold. Electrons are emitted. The emitted electrons are attracted by the high voltage applied to the anode electrode 34 and collide with the corresponding fluorescent layer 32 to emit light. The emission intensity of the pixel-specific fluorescent layer 32 corresponds to the electron beam emission amount of the pixel.

Heat generated from the electron emission unit and the light emitting unit in the driving process as described above is discharged to the outside through the heat sink 22 in contact with the outside air, and removes heat that may accumulate in the light emitting device.

The light emitting device 100 of the above-described embodiment can be used as a backlight unit of the liquid crystal display described below.

FIG. 7 is an exploded perspective view of a liquid crystal display device using a light emitting device as a backlight unit, and FIG. 8 is a partially cutaway perspective view of the liquid crystal panel assembly shown in FIG. 7.

Referring to FIG. 7, the liquid crystal display 200 according to the exemplary embodiment of the present invention may include a liquid crystal panel assembly 210 having arbitrary pixels in a row direction and a column direction, and a rear side of the liquid crystal panel assembly 210. Positioned to provide light to the liquid crystal panel assembly 210.

The light emitting device 100 according to the embodiment of the present invention has a smaller number of pixels than the liquid crystal panel assembly 210 along the row direction and the column direction, so that one pixel of the light emitting device 100 has two or more liquid crystal panel assemblies 210. ) Corresponds to pixels.

Here, the row direction may be defined as one direction of the liquid crystal display 200, for example, the horizontal direction (the x-axis direction in FIG. 6) of the screen implemented by the liquid crystal panel assembly 210, and the column direction may be the liquid crystal display ( Another direction of 200 may be defined as, for example, a vertical direction (y-axis direction in FIG. 6) of a screen implemented by the liquid crystal panel assembly 210.

In this case, the cathode electrode 24 of the light emitting device 100 may be formed in parallel with the column direction, and the gate electrode 28 of the light emitting device 100 may be formed in parallel with the row direction.

The number of pixels of the liquid crystal panel assembly 210 and the number of pixels of the light emitting device 100 along the row direction are referred to as M and M ', respectively, and the number of pixels and the light emitting device 100 of the liquid crystal panel assembly 210 along the column direction. ), The number of pixels (resolution) of the liquid crystal panel assembly 210 can be expressed as M × N, and the number of pixels (resolution) of the light emitting device 100 is M ′ × N. Can be expressed as'

In this case, M and N representing the number of pixels of the liquid crystal panel assembly 210 may be defined as an integer of 240 or more, respectively, and M 'and N' representing the number of pixels of the light emitting device 100 may be any one of 2 to 99. Can be defined as an integer.

According to the above-described configuration, the light emitting device 100 may increase the dynamic contrast ratio of the screen by providing light having different intensity to the pixels of the liquid crystal panel assembly 210 corresponding to each pixel.

Referring to FIG. 8, the liquid crystal panel assembly 210 may include a liquid crystal injected between a transparent third substrate 42 and a fourth substrate 44 and a third substrate 42 and a fourth substrate 44 disposed to face each other. Layer 46; Pixel electrodes 48 and switching elements 50 are formed on an inner surface of the third substrate 42, and a common electrode 52 is formed on an inner surface of the fourth substrate 44.

On the outer surface of the third substrate 42 and the fourth substrate 44, a pair of polarizing plates 54 and 56 having polarization axes orthogonal to each other are positioned, and the alignment layers 58 are disposed to face each other with the liquid crystal layer 46 therebetween. do.

A plurality of gate lines 60 transmitting a gate signal (scan signal) and a plurality of data lines 62 transmitting a data signal are formed on an inner surface of the third substrate 42. The gate lines 60 are located next to each other along the row direction, and the data lines 62 are located next to each other along the column direction.

One pixel electrode 48 is positioned for each sub-pixel and is connected to the gate line 60 and the data line 62 through the switching element 50.

The color filter 64 is disposed between the fourth substrate 44 and the common electrode 52. The color filter 64 is composed of red, green, and blue filters corresponding to one sub-pixel, and three sub-pixels in which three filters of red, green, and blue are located constitute one pixel.

When the switching element 50 is turned on in the liquid crystal panel assembly 210 having the above-described configuration, an electric field is formed between the pixel electrode 48 and the common electrode 52, and the electric field is positioned in the liquid crystal layer 46 by the electric field. The twist angle of the liquid crystal molecules is changed. The liquid crystal panel assembly 210 implements a predetermined color image by controlling the amount of light transmission by adjusting the twist angle of the liquid crystal molecules for each sub-pixel.

9 is a block diagram of a configuration for driving a liquid crystal display device.

Referring to FIG. 9, the liquid crystal display of the present exemplary embodiment is connected to the liquid crystal panel assembly 210, the gate driver 212 and the data driver 214 connected to the liquid crystal panel assembly 210, and the data driver 214. And a gray voltage generator 216, a light emitting device 100, and a signal controller 218 for controlling them.

The liquid crystal panel assembly 210 includes a plurality of signal lines G ₁ -G _n , D ₁ -D _m , and a plurality of pixels PX connected to the signal lines and arranged in a substantially matrix form when viewed in an equivalent circuit. ). The signal lines G ₁ -G _n and D ₁ -D _m are a plurality of gate lines G ₁ -G _n for transmitting a gate signal (also called a “scan signal”), and a plurality of data for transmitting a data signal. Line D ₁ -D _m .

Each pixel PX, for example, the i-th (i = 1,2, ... n) gate line G _i and the j-th (j = 1,2, ... m) data line D _j The pixel 211 connected to includes a switching element Q connected to the signal lines G _i and D _j , a liquid crystal capacitor Clc, and a storage capacitor Cst connected thereto. Holding capacitor Cst can be omitted as needed.

The switching element Q is a three-terminal element such as a thin film transistor, which is provided on the lower substrate (not shown) of the liquid crystal panel assembly 210, the control terminal of which is connected to the gate line G _i , and the input terminal is connected to the data. It is connected to the line D _j , and the output terminal is connected to the liquid crystal capacitor Clc and the storage capacitor Cst.

The gray voltage generator 216 generates two sets of gray voltages (or a set of reference gray voltages) related to the transmittance of the pixel PX. One of the two sets has a positive value for the common voltage Vcom, and the other set has a negative value.

A gate driver 212, the gate lines of the liquid crystal panel assembly _{(210) (G 1 -G n} ) and is connected to the gate turn-on voltage (Von) and the gate line Gate a gate signal which is a combination of a turn-off voltage (Voff) (G ₁ -G _n ).

The data driver 214 is connected to the data lines D ₁ -D _m of the liquid crystal panel assembly 210, selects a gray voltage from the gray voltage generator 216, and uses the data line D ₁ -D as a data signal. _m ). However, when the gray voltage generator 216 provides only a predetermined number of reference gray voltages instead of providing all of the voltages for all grays, the data driver 214 divides the reference gray voltages and thus the gray voltages for all grays. Generate and select the data signal from it.

The signal controller 218 controls the gate driver 212, the data driver 214, the light emitting device controller 220, and the like. The signal controller 218 receives input image signals R, G, and B and an input control signal for controlling the display thereof from an external graphic controller (not shown).

The input image signals R, G, and B contain luminance information of each pixel PX, and luminance has a predetermined number, for example, 1024 (= 2 ¹⁰ ), 256 (= 2 ⁸ ), or 64 ( = 2 ⁶ ) There are grays. Examples of the input control signal include a vertical sync signal Vsync, a horizontal sync signal Hsync, a main clock MCLK, and a data enable signal DE.

The signal controller 218 properly processes the input image signals R, G and B based on the input image signals R, G and B and the input control signal according to the operating conditions of the liquid crystal panel assembly 210, and controls the gate. After generating the signal CONT1 and the data control signal CONT2, the gate control signal CONT1 is sent to the gate driver 212, and the data control signal CONT2 and the processed image signal DAT are transmitted to the data driver 214). In addition, the signal controller 218 transmits the gate control signal CONT1, the data control signal CONT2, and the processed image signal DAT to the light emitting device controller 220.

The light emitting device 100 includes a light emitting device controller 220, a column driver 222, a scan driver 224, and a display unit 226.

The display unit 226 includes a plurality of scan lines S ₁ -S _p for transmitting scan signals, a plurality of column lines C ₁ -C _q for transferring column signals, and a plurality of light emitting pixels EPX. . Each of the plurality of light emitting pixels EPX is positioned in a region defined by scan lines S ₁ -S _p and column lines C ₁ -C _q intersecting the scan lines. Scan lines S ₁ -S _p are connected to scan driver 224, and column lines C ₁ -C _q are connected to column driver 222. In addition, the scan driver 224 and the column driver 222 are connected to the light emitting device controller 220 and operate according to a control signal of the light emitting device controller 220.

The plurality of scan lines S ₁ -S _p are scan electrodes of the above-described light emitting device, and the column lines C ₁ -C _q are data electrodes.

The light emitting device controller 220 generates and transmits a scan driver control signal CS for controlling the scan driver 224 using the gate control signal CONT1. A column driver control signal CC is generated using the data control signal, and a column signal CLS corresponding to the image signal DAT is generated. The generated column driver control signal CS and the column signal CLS are transmitted to the column driver 222. The light emitting device controller 220 generates luminance information for each pixel of the light emitting device 100 from the image signal DAT of one frame, and generates a column signal CLS according to the generated luminance information.

The scan driver 224 sequentially applies a scan signal having a predetermined pulse to the scan lines S ₁ -S _p based on the received scan driver control signal. The column driver 222 applies a driving voltage corresponding to the color signal to each column line C ₁ -C _q according to the input column driver control signal.

By the above-described configuration, the display unit 226 of the light emitting device 100 receives a driving signal synchronized with the image signal and emits light of an appropriate intensity according to the luminance information of each pixel, which is transmitted to the liquid crystal panel assembly 210. to provide. Each of the light emitting pixels EPX of the light emitting device display unit 226 may be driven so that gray scale representation of 2 to 8 bits is possible.

As a result, when the liquid crystal panel assembly 210 displays a screen having different brightness for each position, the light emitting device 100 provides strong light to the pixels of the liquid crystal panel assembly 210 displaying the bright portion, and the dark portion. Weak light may be provided to a portion of the pixels of the liquid crystal panel assembly 210 that displays. In addition, the light emitting pixels of the light emitting device 100 corresponding to the pixels of the liquid crystal panel assembly 210 displaying black may be turned off.

As a result, the liquid crystal display 200 of the present exemplary embodiment may improve the dynamic contrast of the screen through the above-described process.

As described above, the liquid crystal display 200 according to the exemplary embodiment of the present invention uses the light emitting device 100 having the above-described configuration as a backlight unit, and thus, when compared to the conventional CCFL and LED backlight units, Has an advantage.

Since the light emitting device according to the embodiment of the present invention is a surface light source, it does not require a plurality of optical members used in the CCFL type and the LED type backlight unit. Therefore, the liquid crystal display according to the exemplary embodiment of the present invention has almost no light loss generated through the optical member, and does not have to emit excessive intensity light in consideration of the light loss, thereby obtaining excellent efficiency with low power consumption.

In addition, the light emitting device according to the embodiment of the present invention can reduce the cost according to not using the optical member, the manufacturing cost is lower than the LED type backlight unit. In addition, since the light emitting device according to the embodiment of the present invention is easily enlarged, the light emitting device may be easily applied to a large liquid crystal display of 30 inches or more.

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.

The light emitting device according to the embodiment of the present invention is provided with a patterned heat sink between the second substrate and the diffusion plate even when used for high brightness, such as a backlight unit, thereby dissipating heat in the effective area without blocking light. The distance between the second substrate and the diffusion plate can be ensured so that the light can be sufficiently dispersed.

In addition, the liquid crystal display according to the exemplary embodiment of the present invention using the light emitting device as the backlight unit may increase the dynamic contrast ratio of the screen to improve display quality, reduce power consumption, and facilitate enlargement.

Claims (16)

A first substrate and a second substrate disposed to face each other; An electron emission unit provided on an inner surface of the first substrate; A fluorescent layer formed on an inner surface of the second substrate and emitting light by electrons emitted from the electron emission unit; An anode formed on one surface of the fluorescent layer; A spacer maintaining a gap between the first substrate and the second substrate; A diffusion plate formed on the second substrate to disperse light emitted from the fluorescent layer; And A heat sink formed between the second substrate and the diffusion plate; Including; The second substrate is divided into an effective area in which actual light is emitted and an invalid area located outside the effective area, The heat sink is formed in a pattern so that the light emitted from the fluorescent layer in the effective area can pass through. The method of claim 1, The heat sink is made of a hole through which the light emitted from the fluorescent layer passes and a non-hole blocking the light emitted from the fluorescent layer, A light emitting device that satisfies the following conditions when an area occupied by the hole in the effective area is S1 and an area occupied by the non-pore in the effective area is S2. 1 ≤ S1 / S2 ≤ 19 The method of claim 2, And the hole is formed to have a predetermined pitch within the effective area. The method of claim 3, The hole is formed in the light emitting device corresponding to each pixel. The method of claim 1, The heat sink is a light emitting device made of a linear or mesh type. The method of claim 1, The heat sink includes at least one material selected from the group consisting of aluminum (Al), silver (Ag), copper (Cu), and platinum (Pt). The method of claim 1, The heat sink is a light emitting device having a thickness in the range of 0.05 ~ 10 mm. The method of claim 1, The heat sink is formed by depositing a metal material on the second substrate and patterning. The method of claim 1, The heat sink is a light emitting device consisting of a metal plate molded. The method of claim 1, The electron emission unit, A cathode electrode and a gate electrode formed in a direction crossing each other with an insulating layer interposed therebetween; And An electron emission unit connected to the cathode electrode; Light emitting device comprising a. The method of claim 10, The light emitting device of claim 1, wherein the electron emission unit comprises at least one of a carbon-based material and a nanometer-sized material. The light emitting device according to any one of claims 1 to 11; 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 12, And the liquid crystal panel assembly forms a plurality of pixels along a row direction and a column direction, and the light emitting device forms a smaller number of pixels than the liquid crystal panel assembly along the row direction and the column direction. The method of claim 13, The light emitting device is a liquid crystal display device to represent the gray level of 2 to 8 bits (bit) for each pixel. The method of claim 12, The liquid crystal display device in which the said fluorescent layer consists of a white fluorescent layer. The method of claim 12, And a fluorescent layer comprises a red, green, and blue fluorescent layer.

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