KR20080039658A - Light emission device and display using the same - Google Patents

Abstract

A light emission device and a display device using the same are provided to improve display quality by increasing a dynamic contrast ratio of a screen and lower total power consumption by reducing the power consumption of a backlight unit. A light emission device(10) includes a first substrate(12), a second substrate(14), an electron discharging unit(18), and a light emitting unit(20). The second substrate is opposed to the first substrate and is spaced from the first substrate by a predetermined gap. The electron discharging unit is provided on the first substrate. The light emitting unit is provided on the second substrate. The light emitting unit is composed of red, green, and blue fluorescent layers. A transparent thin-film of a predetermined thickness is provided between the green fluorescent layer and the second substrate. The light emission device includes a vacuum container. The vacuum container is composed of a sealing member. The sealing member is provided between the first substrate and the second substrate to bond two substrates.

Description

Light emitting device and display device using same {LIGHT EMISSION DEVICE AND DISPLAY USING THE SAME}

1 is a view showing a trajectory drawn by a black body according to a temperature change in a color coordinate system according to the prior art;

2A is a view showing luminance and color coordinates of white, red, green, and blue when the fluorescent layer is formed by a slurry method according to the prior art;

2B is a view showing luminance and color coordinates of white, red, green, and blue when a fluorescent layer is formed by a slurry method according to the prior art and an Al reflecting film is formed on the fluorescent layer;

2c is a view showing luminance and color coordinates of white, red, green, and blue when a fluorescent layer is formed by a printing-exposure method according to the prior art;

2d is a view showing luminance and color coordinates of white, red, green, and blue when an Al reflection film is provided on a fluorescent layer formed by a printing-exposure method according to the prior art;

3 is a graph showing light transmittance for each wavelength of a bare glass according to the prior art;

4 is a graph showing light transmission characteristics for each wavelength of ITO (indium tin oxide, indium tin oxide) deposited on the bare glass according to the prior art, respectively, in a thickness of 1000 kPa and 2000 kPa;

5 is a table showing the transmission characteristics according to the thickness of ITO in each wavelength region corresponding to R, G, and B in housekeeping rays according to the prior art;

6 is a cross-sectional view schematically showing the configuration of a light emitting device according to an embodiment of the present invention;

7 is an exploded perspective view schematically showing the configuration of a light emitting device according to an embodiment of the present disclosure;

8 is an enlarged view of an enlarged I display unit of FIG. 7;

FIG. 9 is an enlarged view illustrating the III display unit of FIG. 7 in an enlarged manner, and

10 is a partially separated perspective view schematically illustrating a configuration of a liquid crystal display according to an exemplary embodiment of the present invention.

The present invention relates to a light emitting device having an improved white color temperature and a display device using the same.

In general, a flat panel display (FPD) is a substantially flat display device that is thin and relatively low voltage, unlike a cathode ray tube (CRT) that requires a large volume and a high voltage. This includes devices such as field emission displays (FEDs) and vacuum fluoresecent displays (VFDs).

Such a flat panel display device is mainly provided with an electron emission unit for emitting electrons to the cathode substrate, and the anode substrate is provided with a light emitting unit for emitting light in the process of absorbing and exciting energy by the collision of electrons emitted from the electron emission unit. .

The light emitting unit is positioned between the fluorescent layer made of red (R), green (G), and blue (B) on the anode substrate, the reflective film of the metal covering the fluorescent layer, and the R, G, and B fluorescent layers to achieve contrast of the screen. It consists of a black layer which improves.

Here, the reflective film is applied with a voltage higher than that of the cathode substrate to induce electrons toward the anode substrate, and when the electrons collide with the fluorescent layer, the reflective film has a mirror function to re-reflect the electrons reflected toward the cathode substrate toward the anode substrate, and the electrons to the fluorescent layer By flowing unstacked, it increases the life of the fluorescent layer and prevents arcing between the two substrates.

Heating the black body turns from red to orange, yellow and white, and gradually turns the blue color into a strong light. When heat is applied at the absolute temperature of 0 degrees (-273 degrees), which is the lowest temperature, electromagnetic waves (radiation waves) are emitted. Color properties are expressed as the unit of absolute temperature at this time. This is called "Kelvin" and is denoted by "K". The blackbody is the ideal object to completely absorb and completely re-radiate all incident light, following the Planck radiation equation.

S (λ, T) = (2hc ² / λ ⁵ ) / (e ^{hc / kTλ} -1)

Where c is the luminous flux and h is the Planck's constant. From this equation, the intensity of radiant energy according to the temperature and wavelength of the blackbody can be known. Blackbody radiation is used to estimate the temperature of a furnace or star. Since the radiation distribution function is a function of the wavelength λ and the temperature T, it is possible to know the radiation distribution function S (λ) for each wavelength λ by knowing the blackbody temperature T. By knowing the radiation distribution function (λ), the X, Y, Z and x, y color coordinates can be known, and thus the blackbody temperature T can be known as the color coordinates of x and y.

1 shows a trajectory drawn by a complete radiator (black body) in accordance with temperature change in a color coordinate system. At present, the color temperature expressed in the FED is about 7,000K to 8,000K at the anode low pressure of 7kV, which is somewhat lower than the target 10,000K.

2A to 2D are each a case where a fluorescent layer is formed by a slurry method, a fluorescent layer is formed by a slurry method, and an Al reflecting film is formed on the fluorescent layer, a fluorescent layer is formed by a printing-exposure method, and In the case where the Al reflection film is provided on the fluorescent layer formed by the printing-exposure method, luminance and color coordinates of white (W), red (R), green (G), and blue (B) are shown.

According to FIG. 2A, the R / B and G / B luminance ratios are 2.2 and 3.9, respectively, and the white color coordinates have a value of 12,672K, while the R / B and G / B luminance ratios are increased in FIGS. 2C and 2D. As can be seen that leads to a decrease in color temperature. Therefore, in the fluorescent layer formed by the print-exposure method, it is evident that the R / B luminance ratio and the G / B luminance ratio must be reduced than in the present for the increase of the white color temperature.

Therefore, in order to improve the white color temperature, it can be seen that it is required to lower the luminance of green (G) under the existing fluorescent layer conditions.

3 is a graph showing light transmittance for each wavelength of a bare glass. Referring to FIG. 3, it can be seen that the transmittance is approximately 86 to 88% in all wavelength ranges of the visible light.

FIG. 4 shows light transmission characteristics of wavelengths obtained by depositing and evaluating ITO (indium tin oxide) on a bare glass at a thickness of 1000 mW and 2000 mW, respectively.

5 shows the transmission characteristics according to the thickness of ITO in each wavelength region corresponding to R, G, and B in the house beam.

4 and 5, the light transmittances in the B and R regions are not significantly different when the ITO thickness is 1000 GPa and when the thickness is 2000 GPa, while the light transmittance in the G region is higher than when the ITO thickness is 1000 GPa. This is about 14-15% lower. In other words, if ITO of 2000 mW is used, the luminance of the G wavelength range is relatively decreased in B or R compared to the area band than in the case of no ITO or an anode having ITO of 2000 m or less.

Accordingly, an object of the present invention is to provide a light emitting device that can achieve an effect of increasing white color temperature by lowering a luminance ratio of G / B.

Another object of the present invention is to provide a display device to which the above-described light emitting device is applied.

The present invention to achieve the above object is a first substrate; A second substrate facing the first substrate and disposed at a predetermined interval; An electron emission unit provided on the first substrate; And a light emitting unit provided on the second substrate, wherein the light emitting unit is formed of fluorescent layers of red (R), green (G), and blue (B), and the green (G) fluorescent layer and the second There is provided a light emitting device in which a transparent thin film having a predetermined thickness t is provided between substrates.

The transparent thin film may be made of ITO, and the thickness t of the transparent thin film may be formed larger than 0.1 μm and smaller than 1.0 μm. Alternatively, it can be formed larger than 0.1 and smaller than 0.3㎛.

A black layer may be further included between the fluorescent layers, and an anode electrode may be formed on one surface of the fluorescent layers and the black layer. The anode electrode may be made of a metal film.

The electron emitting unit includes a first electrode formed on the first substrate; An insulating layer covering the first electrode and formed on the entire first substrate; A second electrode formed to cross the first electrodes on the insulating layer; And an electron emission part formed on the first electrode in a region where the first electrode and the second electrode cross each other.

According to another embodiment of the present invention, there is provided a display device including a panel assembly positioned in front of the above-described light emitting device and receiving the light emitted from the light emitting device to display an image.

The panel assembly may be applied to a liquid crystal panel assembly.

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. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In an embodiment of the present invention, the light emitting device includes all devices capable of recognizing that light is emitted when viewed from the outside. Therefore, all display apparatuses that display information by displaying symbols, alphanumeric characters, and images, are also included in the light emitting apparatus. The light emitting device may be used as a light source for providing light to the light receiving display panel.

6 to 9 are views illustrating a configuration of a light emitting device according to an embodiment of the present invention.

6 to 8, a light emitting device 10 according to an exemplary embodiment of the present invention may include a first substrate 12 and a second substrate 14 that are disposed to face each other in parallel at a predetermined interval, and a first substrate. And a vacuum container composed of a sealing member 16 disposed between the 12 and the second substrate 14 to join the two substrates.

Spacers 34 are positioned between the first substrate 12 and the second substrate 14 to support the compressive force applied to the vacuum vessel and to keep the distance between the two substrates constant.

The first substrate 12 and the second substrate 14 may be divided into an effective region contributing to the actual visible light emission and an ineffective region surrounding the effective region. The effective area of the first substrate 12 is provided with an electron emission unit 18 for electron emission, and the effective area of the second substrate 14 is provided with a light emission unit 20 for visible light emission.

The electron emission unit 18 includes first electrodes 24 and second electrodes 26 and first electrodes 24 formed in a stripe pattern along a direction crossing each other with the insulating layer 22 therebetween, and the first electrodes 24. ) And electron emitters 28 electrically connected to any one of the second electrodes 26.

When the electron emission portion 28 is formed on the first electrode 24, the first electrode 24 becomes a cathode electrode for supplying current to the electron emission portion 28, and the second electrode 26 is a cathode electrode. An electric field is formed by the voltage difference between and the gate electrode is used to induce electron emission. On the contrary, when the electron emission portion is formed in the second electrode, the second electrode becomes a cathode electrode and the first electrode becomes a gate electrode.

In the drawing, openings 261 and 221 are formed in the second electrodes 26 and the insulating layer 22 at the intersections of the first electrode 24 and the second electrode 26 to partially remove the surface of the first electrode 24. The case where the electron emission part 28 is positioned on the first electrode 24 is exposed and exposed inside the opening 221 of the insulating layer 22. The position of the electron emission unit 28 is not limited to the illustrated example and can be variously modified.

The electron emission unit 28 may be formed of materials emitting electrons when an electric field is applied, such as a carbon-based material or a nanometer-sized material. The electron emission unit 28 may include, for example, a material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbon, fullerene (C ₆₀ ), silicon nanowires, and combinations thereof. Screen printing, direct growth, chemical vapor deposition or sputtering may be applied to the preparation method.

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 20 is disposed between the red (R), green (G) and blue (B) fluorescent layers 30R, 30G, 30B, and the fluorescent layers 30R, 30G, 30B. The black layer 31 and the anode electrode 32 positioned on one surface of the fluorescent layers 30R, 30G, and 30B to enhance the contrast of the screen are included. The fluorescent layers 30R, 30G, and 30B may be divided and positioned in a predetermined pattern in one pixel area.

Referring to FIG. 9, a transparent thin film 35 having a predetermined thickness is provided between the green fluorescent layer 30G and the second substrate 14. By adopting the transparent thin film 35, the luminance of the green (G) wavelength range is reduced compared to the blue (B) or red (R) range, thereby lowering the luminance ratio of G / B, thereby increasing the effect of white color temperature. You can get it.

The transparent thin film 35 may be made of, for example, ITO, and the thickness t may be greater than 0.1 μm and smaller than 1.0 μm. (0.1 μm <t <1.0 μm)

Or the thickness t can be formed larger than 0.1 micrometer and smaller than 0.3 micrometer. (0.1 μm <t <0.3 μm)

The anode electrode 32 may be formed of a metal film such as aluminum (Al) covering the surfaces of the fluorescent layers 30R, 30G, and 30B. The anode electrode 32 is an acceleration electrode for attracting an electron beam to maintain the fluorescent layers 30R, 30G, and 30B in a high potential state by applying a high voltage, and is the first of visible light emitted from the fluorescent layers 30R, 30G, and 30B. The visible light emitted toward the substrate 12 is reflected toward the second substrate 14 to increase the luminance of the light emitting surface.

The light emitting device 10 having the above-described configuration applies a predetermined driving voltage to the first electrodes 24 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 30. Drive by applying voltage.

Then, in the pixels where the voltage difference between the first electrode 24 and the second electrode 26 is greater than or equal to the threshold, an electric field is formed around the electron emission unit 28, and electrons are emitted therefrom, and the emitted electrons are attracted to the anode voltage to correspond. It emits light by colliding with a portion of the fluorescent layer. The emission intensity of the fluorescent layer for each pixel corresponds to the electron beam emission amount of the corresponding pixel.

10 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment using the light emitting device having the above-described configuration as a backlight unit.

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

Any known liquid crystal panel assembly may be applied to the liquid crystal panel assembly 52, and an optical member (not shown), such as a diffusion plate or a diffusion sheet, may be disposed between the liquid crystal panel assembly 52 and the backlight unit as necessary. have.

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. To respond. Each pixel of the backlight unit 10 may emit light corresponding to the highest gray level among the plurality of liquid crystal panel assembly pixels, and the backlight unit 10 may express a gray level of 2 to 8 bits for each pixel.

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 driving of the backlight unit 10, the signal controller which controls the liquid crystal panel assembly 52 detects the highest gray level among the first pixels of the first pixel group, and adjusts the gray level required for emitting the second pixel according to the detected gray level. The calculation may be performed by converting the digital data into digital data and generating a driving signal of the backlight unit using the digital data. Therefore, when the image is displayed in the corresponding first pixel group, the second pixel of the backlight unit may emit light with 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 in the drawing) of the screen implemented by the liquid crystal panel assembly 52, and the column direction may be different from that of the liquid crystal display device. One direction, for example, may be defined as a vertical direction (y-axis direction of the drawing) of the screen implemented by the liquid crystal panel assembly.

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. If the number of pixels of the backlight unit in the row direction and the column direction exceeds 99, driving of the backlight unit becomes complicated and may cause a cost increase for manufacturing a driving circuit.

As described above, 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 independently controls the light emission intensity for each pixel to provide light of an appropriate intensity for the liquid crystal panel assembly pixels corresponding to each pixel. To provide. Therefore, the liquid crystal display of the present embodiment can increase the dynamic contrast of the screen and can realize a clearer picture quality.

The light emitting device according to the present invention can obtain the effect of increasing the white color temperature by providing a transparent thin film between the green fluorescent layer and the second substrate to lower the luminance ratio of G / B.

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

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.

Claims (10)

A first substrate; A second substrate facing the first substrate and disposed at a predetermined interval; An electron emission unit provided on the first substrate; And Light emitting unit provided on the second substrate Including; The light emitting unit includes red (R), green (G), and blue (B) fluorescent layers, and a transparent thin film having a predetermined thickness (t) is disposed between the green (G) fluorescent layer and the second substrate. Provided light emitting device. The method of claim 1, The transparent thin film is a light emitting device made of ITO. The method of claim 1, And a thickness t of the transparent thin film is larger than 0.1 µm and smaller than 1.0 µm. The method of claim 3, And a thickness t of the transparent thin film is greater than 0.1 µm and smaller than 0.3 µm. The method of claim 1, The light emitting device further comprises a black layer between the fluorescent layers. The method of claim 5, An anode electrode is formed on one surface of the fluorescent layers and the black layer. The method of claim 6, The anode electrode is made of an Al metal film. The method of claim 1, The electron emitting unit, A first electrode formed on the first substrate; An insulating layer covering the first electrode and formed on the entire first substrate; A second electrode formed to cross the first electrodes on the insulating layer; And An electron emission part formed on the first electrode in a region where the first electrode and the second electrode cross each other; Light emitting device comprising a. The light emitting device according to any one of claims 1 to 8; And A panel assembly positioned in front of the light emitting device to receive light emitted from the light emitting device to display an image; Display device comprising a. The method of claim 8, A display device comprising the panel assembly as a liquid crystal panel assembly.

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