KR20170133553A - Backlight unit comprising light absortion sheet and liquid crystal display device comprising thereof - Google Patents

Abstract

The present invention relates to a backlight unit including a light absorption sheet and a liquid crystal display apparatus including the same. The backlight unit according to an embodiment of the present invention comprises: a light source part emitting light to three distinct wavelength bands; and a light absorption sheet absorbing light in a part having weak boundaries and converting the light into white light in the three distinct wavelength bands. Therefore color reproduction ratio can be increased in the liquid crystal display apparatus.

Description

BACKLIGHT UNIT COMPRISING LIGHT ABSORTION SHEET AND LIQUID CRYSTAL DISPLAY DEVICE COMPRISING THEREOF FIELD OF THE INVENTION The present invention relates to a backlight unit including a light absorbing sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit including a light absorbing sheet and a liquid crystal display including the same.

The display device (or the display device) is a device for visually displaying data, and includes a liquid crystal display, an electrophoretic display, an organic light emitting display, A cathode ray tube, an electro luminescent display, a field emission display, a surface-conduction electron-emitter display, a plasma display, and a cathode ray tube (Cathode Ray) Display).

2. Description of the Related Art Liquid crystal display devices (LCDs) are electronic devices that transmit various electrical information generated from various devices into visual information using a change in liquid crystal transmittance according to an applied voltage. The liquid crystal display device is widely used as an alternative means capable of overcoming the disadvantages of the CRT (Cathode Ray Tube), which has been used conventionally, and has the advantages of mass production capability, ease of driving means, realization of high image quality, to be.

The liquid crystal display device includes a liquid crystal display panel for displaying an image, a backlight unit (BLU) for irradiating light to the liquid crystal display panel, a drive circuit unit for driving the liquid crystal display panel, A chassis unit for fastening the respective components together, and the like.

The backlight unit includes a red light source, a green light source, and a blue light source in order to illuminate white light with a liquid crystal display panel. The light source unit includes a light emitting diode package including a light emitting diode (LED) .

Thus, when the light emitting diode chip is used as a light source for each color, the light emitting diode chip is expensive, and thus a considerable cost is required for manufacturing the light emitting diode package. Particularly, compared to the blue light emitting diode chip, the green light emitting diode chip and the red light emitting diode chip are considerably expensive. Accordingly, in order to emit white light, the backlight unit may use all of the light sources of three colors, or the white light may be emitted by coupling a color conversion material such as a fluorescent material to the blue LED.

However, the white light that combines a particular color with a material that converts it has a limitation in high color reproduction due to the fact that green, red, and blue are not distinguished clearly. Accordingly, there is a need for a backlight unit and a display device including the backlight unit, in which color classification for high color reproduction is made clear.

The present invention provides a backlight unit that emits light having a narrow bandwidth by absorbing light in a wavelength band that is a boundary between colors, and a liquid crystal display device including the backlight unit.

An object of the present invention is to provide a backlight unit that increases the intensity of light corresponding to a specific wavelength band in a light source unit and a liquid crystal display device including the backlight unit in order to increase a high color reproduction rate due to absorption of light in a wavelength band which is a boundary between colors.

The present invention is intended to realize a backlight unit which absorbs light superimposed at the boundary between green and red to enhance the color reproduction ratio of red and green, and a liquid crystal display including the same.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description and more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

The backlight unit according to an embodiment of the present invention includes a light source unit that emits light in two distinct wavelength bands and a light absorbing sheet that converts the light into white light of three distinct wavelength bands.

A backlight unit according to another embodiment of the present invention includes a light source unit that emits light in three distinct wavelength bands and a light absorbing sheet that absorbs light in a weak boundary and converts the light into white light of three distinct wavelength bands .

A liquid crystal display device according to another embodiment of the present invention includes a backlight unit including a light absorbing sheet for absorbing light in a boundary region between green and red and a backlight unit for displaying an image using white light emitted from the above- And includes a liquid crystal display panel.

In the case of applying the present invention, since the white light enhanced in red and green is emitted from the backlight unit, the color reproduction rate can be increased in the liquid crystal display device.

When the present invention is applied, the light source part of the backlight unit increases the distribution of the color conversion factors so that the green and red colors are sufficiently expressed, and the color mixture due to the increase of the color conversion factors is converted into light of a specific wavelength band It is possible to reproduce not only the blue color but also the green and red colors in depth to increase the DCI overlap ratio of the white light.

When the present invention is applied, the light absorbing sheet and the color conversion factor can be added or controlled in the backlight unit to emit white light, so that the process cost is not complicated but the process cost is also low so that not only efficiency of color reproducibility, The efficiency can be increased.

The effects of the present invention are not limited to the effects described above, and those skilled in the art of the present invention can easily derive the various effects of the present invention in the constitution of the present invention.

1 is a view showing a structure of a backlight unit to which an optical sheet of the present invention is coupled.
2 is a view illustrating the configuration of a liquid crystal display panel and a backlight unit according to an embodiment of the present invention.
3 is a view showing the structure of a light absorbing sheet including a light absorbing layer according to an embodiment of the present invention.
4 is a view showing a process of manufacturing a light absorbing sheet according to an embodiment of the present invention.
FIGS. 5 and 6 are diagrams showing changes in incident light and emitted light by the light absorbing layer according to an embodiment of the present invention.
FIG. 7 is a diagram illustrating a configuration and a spectrum of a light source according to an embodiment of the present invention.
8 is a view illustrating an operation of a backlight unit according to an embodiment of the present invention.
9 is a view illustrating an operation of a backlight unit according to another embodiment of the present invention.
10 is a view showing a configuration of an optical sheet including a light absorbing sheet according to an embodiment of the present invention.
11 is a view showing a configuration of a light absorbing sheet according to an embodiment of the present invention.
12 is a diagram showing DCI superposition degree when one embodiment of the present invention is applied.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings so that those skilled in the art can easily carry out the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification. Further, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to denote like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, the terms first, second, A, B, (a), (b), and the like can be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.

The present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As shown in FIG.

Hereinafter, the display device will be described mainly with reference to a liquid crystal display device, but the present invention is not limited thereto and can be applied to various display devices requiring a separate light source.

In addition, the light source constituting the backlight unit will be described mainly with reference to the LED, but the present invention is not limited thereto, but may be combined with various light source modules emitting white light.

Hereinafter, the optical sheet according to one embodiment of the present invention can be coupled to the above-described backlight unit. The backlight unit is roughly divided into two types of edge type and direct type.

1 is a view showing a structure of a backlight unit to which an optical sheet of the present invention is coupled.

Referring to FIG. 10, a light source unit 110 having a light emitting diode package as an example is disposed on a front surface of a liquid crystal display panel 90. 10, the light from the light source unit 110 passes through the optical sheet 150 and enters the liquid crystal display panel 90. The light source unit 110 is closely located below the liquid crystal display panel 90 and directly illuminates the liquid crystal display panel 90 in a direct-type backlight unit (Direct BLU) The direct-type backlight unit 100a includes a light source unit 110 and an optical sheet 150. [ Further, the optical sheet 150 of the present invention includes a light absorbing sheet to be described later.

The light source unit 110 having the light emitting diode package as an example is disposed at the side of the liquid crystal display panel 90, that is, at the edge portion of the liquid crystal display panel 90. [ 20, the light source unit 110 emits (emits) light to the upper surface by a light guide panel (LGP) 130 and a reflection plate 120. The light emitted from the light source unit 110 located on the side of the liquid crystal display panel 90 is reflected by the reflection plate 120 along the light guide plate 130 and irradiated to the liquid crystal display panel 90. In this process, a change in the spectrum of light may occur in the optical sheet 150. [ In particular, according to one embodiment of the present invention in which the optical sheet 150 includes a light absorbing sheet, the irradiated light passes through the optical sheet 150 and enters the liquid crystal display panel 90. The edge type backlight unit 100b includes a light source unit 110, a light guide plate 130, a reflection plate 120, and an optical sheet 150. [

When the light emitting diode package is used as the light source of the backlight units 100a and 100b according to the embodiments, the backlight units 100a and 100b may include a light source that emits red light, A light source that emits light, and a light source that emits blue light.

In addition, the light emitting diode package may include a specific color hue and a color conversion factor that causes conversion of light. The color conversion factor may be a fluorescent material, a color conversion filter, or the like.

The optical sheet converts light emitted from the light source and emits the light as light of another attribute. The optical sheet according to an embodiment of the present invention refers to a device that converts an attribute of input light and outputs the light as light of another attribute. More specifically, the optical sheet according to an embodiment of the present invention includes a light absorbing sheet, and the light absorbing sheet absorbs light in a specific wavelength band.

2 is a view illustrating the configuration of a liquid crystal display panel and a backlight unit according to an embodiment of the present invention. The structure of the edge system of FIG. 1 will be mainly described, but the present invention is not limited thereto.

2, the liquid crystal display device 50 includes a liquid crystal display panel 90, a light source unit 110, a backlight unit including a light guide plate 130, a reflection plate 120, and an optical sheet 150, And a frame 80 that fixes the image so that an image can be displayed using the light of the backlight unit.

In FIG. 2, the optical sheet 150 may be composed of a plurality of sub-optical sheets. For example, one embodiment of the suboptical sheet is meant to be disposed in film form. The sub optical sheet provides various functions such as improving brightness or diffusing light. As an example of the sub optical sheet, a dual brightness enhancement film (DBEF), a prism sheet, a diffusion sheet, or the like can be used.

In the embodiment of FIG. 2, the DBEF 210, the prism sheet 220, and the light absorption sheet 230 are formed. In the light absorbing sheet 230 according to the embodiment of the present invention, a light absorbing layer for absorbing a specific wavelength band of light is disposed. The order of the prism sheet 220 and the light absorbing sheet 230 may be varied, and only one prism sheet having a light absorbing layer may be included in the optical sheet 150.

The light absorbing layer according to an embodiment of the present invention absorbs light of a specific wavelength band in order to convert the light emitted from the light source into white light. For example, a phosphor may be included in a light source to emit red light and green light in a light emitting diode emitting blue light. However, when an optical sheet including a light absorbing layer, i.e., a light absorbing sheet, is used, the color reproduction ratio of blue, red, and green is increased, Can be reproduced. 2, the light absorbing sheet 230 includes a light absorbing layer. The light absorbing sheet 230 including the light absorbing layer can provide both the function of the prism sheet and the light absorbing function. Therefore, the light absorbing sheet is a prism sheet to which a light absorbing layer is bonded.

3 is a view showing the structure of a light absorbing sheet including a light absorbing layer according to an embodiment of the present invention.

The light absorbing sheet of Fig. 3 is a structure in which a light absorbing layer is disposed on the lower surface of a prism sheet for increasing the brightness of incident light. On the first surface of the light absorbing sheet, a pattern layer 231 for increasing the diffusion and luminance of light, a support layer 232 for supporting the pattern layer, and a light absorbing layer 300 are formed. One example of the light absorbing layer includes TAP (Tetra Aza Porphyrin). In detail, the pattern layer 231 of the light absorbing sheet 230 is an acrylic layer and the supporting layer 232 is a base PET film, a base PC film (Base Polycarbonate Film), or a base PS film Base PolyStyrene Film) as one embodiment. The height of the support layer 232 may be 250 um. The light absorbing layer 300 may be formed using an acrylic binder.

4 is a view showing a process of manufacturing a light absorbing sheet according to an embodiment of the present invention. The support layer 232 and the pattern layer 231 are formed of a base PET film, a base polymer film, or a base PS film, as shown in FIG. When the film 235 shown in 401 is used independently, it can be a prism sheet. Reference numeral 402a is a process of applying a light absorbing agent for producing the light absorbing layer 300 on the films 231 and 232. [ The light absorbing layer 300 can be formed on the film 235 as shown in 403 by applying the light absorbing agent in the nozzle 420.

And 402b is a process of coating a light absorbing agent for producing the light absorbing layer 300 on the films 231 and 232. [ And may be coated as roll 300a using roller 430 for coating.

When the light absorbing layer 300 is formed as shown in 402a or 402b, the light absorbing sheet is completed as in 403. Since the light absorbing layer 300 of the light absorbing sheet absorbs light of a specific wavelength range and filters the light, the region where the colors overlap can be removed. Accordingly, a spectrum having a narrow bandwidth can be formed to realize a high color reproduction.

FIGS. 5 and 6 are diagrams showing changes in incident light and emitted light by the light absorbing layer according to an embodiment of the present invention. As described above, the incident light 501 is absorbed by the light absorbing sheet 230 in the wavelength band of about 590 nm as indicated by 502 and 502a in the entire spectrum, and emitted as white light as 503. In more detail, the change in light is examined in FIG.

Reference numeral 501 in FIG. 6 is a spectrum of light generated in the light source. The wavelength band B corresponding to the blue color on the left in 501 is distinguished from the wavelength band of the other light. However, the wavelength band G corresponding to the center green and the wavelength band R corresponding to the red color are not distinguished as indicated by 501a. This is because light that causes color mixing is left between the wavelength band G corresponding to green and the wavelength band R corresponding to red. This incident light is absorbed by the light absorbing sheet 230 in the region indicated by 502a. As a result, the spectrum of the light 503 transmitted through the light absorbing sheet 230 has a very low intensity of light between the green wavelength band G and the red wavelength band R, as indicated by 503a.

5 and 6, the light-absorbing sheet according to the embodiment of the present invention converts incident light not white light, or a mixture of a spectrum of which is not suitable for reproduction of a high color, into white light of high color reproduction rate . In addition, in the case of the light source to be combined with the light absorbing sheet of the present invention, it is not necessary to lower the brightness to emit white light, and the light source of the present invention emits light having a high intensity of green and red, can do.

FIG. 7 is a diagram illustrating a configuration and a spectrum of a light source according to an embodiment of the present invention.

The conventional light source is composed of a blue light source and a color conversion factor (Red Phosphor + Yellow Phosphor) for generating red and green so that the emitted light becomes white. On the other hand, in the embodiment of the present invention, the composition ratio of the color conversion factor of the light source 710 can be increased. That is, the composition ratio of the color conversion factors 712 arranged in the blue LEDs 711 and 712 is high.

Comparing the spectrum 730a of the conventional light source indicated at 730 with the spectrum 730b of the embodiment of the present invention, since the distribution of the color conversion factor is low in the conventional light source, the intensity of the light in the blue wavelength band is high, The intensity of the light in the wavelength band was low. On the other hand, in the spectrum 730b of the light source according to the embodiment of the present invention, the intensity of light in the blue wavelength band is low and the intensity of light in the green and red wavelength bands is high, as compared with 730a. 730b, the light emitted from the light source has a weak blue color and a mixed color of green and red. However, by applying the light-absorbing sheet of the present invention, it is possible to obtain a blue light, a green light, Light having a narrow bandwidth is emitted.

In summary, the backlight unit according to an embodiment of the present invention converts light divided into two wavelength bands differently from a conventional light source, and divides the light into three wavelength bands, thereby enabling high color reproduction of white light.

8 is a view illustrating an operation of a backlight unit according to an embodiment of the present invention. For convenience of explanation, the light source unit 810 is disposed in a direct-down manner, but the present invention is not limited thereto. 8, the edge system of FIG. 2 in which the light guide plate and the reflection plate are disposed at the portion where the light source units 810 are disposed is included in the present invention.

The light source unit 810 includes a blue LED (Light Emitting Diode), a yellow color conversion factor, and a red color conversion factor. The light emitted from the light source unit 810 by adjusting the distribution of the yellow color conversion factor and the red color conversion factor has a spectrum configuration divided into a first wavelength band 801a and a second wavelength band 801b. That is, the light emitted from the plurality of light source units 810 is divided into two wavelength bands 801a and 801b, which are classified by the region 809 in which the intensity of light is low. In one embodiment, the first wavelength band 801a corresponds to the blue wavelength band and the second wavelength band 801b corresponds to the green wavelength band and the red wavelength band. Here, the green wavelength band and the red wavelength band are included in the second wavelength band 801b, but there is no light having a weak intensity to the extent indicated by 809 in an intermediate point or an intermediate point in the second wavelength band 801b. That is, in a region near the middle point or the middle point of the second wavelength band 801b, a value Intensity_B of the intensity of light having a low intensity 809, which distinguishes between the first wavelength band 801a and the second wavelength band 801b, There is no point to have.

This can be expressed by the following equation.

Intensity_GR, which is the minimum intensity of the light in the second wavelength band 801b when the lowest wavelength is WL_Green_Low and the highest wavelength is WL_Red_High at the central portion 891 of the second wavelength band 801b, has the following relationship I have. The central portion of the second wavelength band 801b may be a region of 520 nm or more and 650 m or less in which green and red may be mixed, but the present invention is not limited thereto.

[Equation 1]

Intensity_GR = min (Intensity (WL_i)) where WL_Green_Low <= WL_i <= WL_Red_High;

Intensity_B <Intensity_GR;

In summary, light incident on the light absorbing sheet 830 in the light source unit 810 according to an embodiment of the present invention is divided into a first wavelength band 801a and a second wavelength band 801b, Intensity_B is lower than Intensity_GR, which is the intensity of light at the point where the light intensity is lowest at the central portion of the band 801b. In order to enhance the intensity of red and green, a yellow color conversion factor and a red color conversion factor are used to increase the intensity of red and green, because the light absorbing sheet 830 absorbs light in a wavelength band for separating red and green at the center of the second wavelength band 801b. The distribution of factors can be increased. The light source unit 810 can emit red light and green light with stronger intensity to enhance the color expression of red and green. By applying the light absorbing sheet 830, the bandwidth of red and green can be narrowed, Increasing the DCI overlap ratio and enabling high color reproduction.

Intensity_GR, which is the minimum value of the intensity of light in the second wavelength band 801b, is a minimum value of the intensity of the light of the first wavelength band and the second wavelength band boundary, Intensity_B. &Lt; / RTI &gt; Intensity_GR may correspond to the value of the lowest light intensity at a central portion (for example, 520 nm or more and 650 m or less) in the second wavelength band 801b.

One embodiment of the first wavelength band 801a is 400 nm to 480 nm in one embodiment. And the second wavelength band 801b is 490 nm to 700 nm as green light. In addition, the wavelength band for absorbing light is 590 nm as an example, and may have a range of 5 nm or 10 nm or the like as a wider region. That is, the light-absorbing sheet according to one embodiment of the present invention can absorb light positioned between 580 nm and 600 nm. However, the present invention is not limited to these numerical values, and can be applied to various wavelength bands. That is, when the embodiment of the present invention is applied, it is possible to increase the intensity of light of a specific spectrum, and absorb light of a certain wavelength band out of the raised portions and emit light having a narrow bandwidth.

Conventionally, in the light source part, the distribution of the color conversion factors such as the fluorescent material is reduced in order to prevent the color mixture in the overlapping part such as green-red, and the color reproduction ratio of green and red is lower than that of blue. However, when the present invention is applied, the distribution of the color conversion factors is increased so that the green and red colors are sufficiently expressed in the light source unit 810, and the color mixture due to the increase of the color conversion factors is specified Light of a wavelength band can be absorbed, so that not only blue but also green and red can be reproduced. Particularly, the light-absorbing sheet 830 and the color conversion factor are not complicated, and the process cost is also low, so that not only efficiency of color reproducibility but also efficiency in process and price is high.

Meanwhile, the light-absorbing sheet 830 according to an embodiment of the present invention may have a specific wavelength range such as a green wavelength band and a red wavelength band, for example, 802, so that the second wavelength band 801b can be distinguished from the light having the same characteristic as 801. [ And absorbs light of a wavelength band corresponding to 802a so that the band can be distinguished. As a result, the light 803 transmitted through the light-absorbing sheet 830 emits 801a in the first wavelength band 803a and its waveform and corresponds to the blue wavelength band. The second wavelength band is divided into a second-first wavelength band such as 803b and a second-2 wavelength band such as 803c. The second-1 wavelength band 803b corresponds to the green wavelength band, and the second-2 wavelength band 803c corresponds to the red wavelength band. Therefore, the light 803 having a high color reproduction is emitted.

8, a yellow color conversion factor and a red color conversion factor are used to indicate the green and red colors of the light source unit 810 using the blue LED, and the second color conversion factor and the red color conversion factor are used in the light absorption sheet 830, The intensity of the green and red light can be increased by absorbing light in the wavelength band of the boundary so that the one-wavelength band 803b and the second-2-wavelength band 803c are separated.

As shown in FIG. 8, it is possible to absorb a part of the wavelength band of the light divided into the two separated wavelength bands and to output the three different wavelength bands to realize the high color reproduction.

8, a light source section 810 that emits light divided into a first wavelength band 801a and a second wavelength band 801b, and a light source section 810 that emits light in a part of the wavelength band 802a of the second wavelength band 801b. And a liquid crystal display device including the backlight unit according to an embodiment of the present invention.

The light absorbing sheet 830 has a first wavelength band 803a and a second wavelength band 803b separated by the incident first and second wavelength bands 801a and 801b, And the second-second wavelength band 803c. The wavelength band 802a where the light absorbing sheet 830 absorbs light is a wavelength band between the second-first wavelength band 803b and the second-second wavelength band 803c. Absorbing sheet 830 absorbs light in the region to be mixed, the light source unit 810 can increase the intensity of green and red, thereby enhancing both the blue / green / red, thereby increasing the light efficiency and increasing the color recall.

As shown in FIG. 2, the light absorbing sheet 830 may be in close contact with any one of the DBEF 210 and the prism sheet 220, which is a double brightness enhancement film. The order of the DBEF, the prism sheet, and the light absorbing sheet can be variously configured.

According to an embodiment of the present invention, a backlight unit 810 including a light source unit 810 that emits light in two distinct wavelength bands and a light absorbing sheet 830 that converts the light into white light of three distinct wavelength bands, Can be implemented.

9 is a view illustrating an operation of a backlight unit according to another embodiment of the present invention. For convenience of explanation, the light source unit 910 is disposed in a direct-down manner, but the present invention is not limited thereto. 9, the edge method of FIG. 2 in which the light guide plate and the reflection plate are disposed at the portion where the light source portions 910 are disposed is also included in the present invention.

The light 901 emitted from the light source unit 910 has a spectrum configuration divided into a first wavelength band 901a, a second wavelength band 901b, and a third wavelength band 901c. That is, the light emitted from the plurality of light source units 910 is divided into three wavelength bands 901a, 901b, and 901c, which are divided into regions 909a and 909b in which the intensity of light is low. In one embodiment, the first wavelength band 901a corresponds to the blue wavelength band, the second wavelength band 901b corresponds to the green wavelength band, and the third wavelength band 901c corresponds to the red wavelength band. Here, there is a distinction such as 909b between the green wavelength band and the red wavelength band. However, when Intensity_B, which is the intensity of light at 909a, and Intensity_Pre, which is the intensity of light at 909b, are compared, it has a relationship of Intensity_Pre> Intensity_B. That is, the distinction is not large between the second wavelength band 901b and the third wavelength band 901c. That is, the light emitted from the light source unit 910 according to an exemplary embodiment of the present invention has a spectrum equal to 901.

On the other hand, the light absorbing sheet 930 according to the embodiment of the present invention converts light having the same characteristics as 901. A green wavelength band and a red wavelength band can be distinguished as a specific region, for example, 902a, so that the second wavelength band 901b and the third wavelength band 901c can be distinguished from the light 901 emitted from the light source unit 910 Absorbs light in a wavelength band corresponding to 902a. As a result, the spectrum of the light 903 transmitted through the light absorbing sheet 930 will be described. The first wavelength band 903a maintains its waveform when compared with the first wavelength band 903a, but the second wavelength band 903b, Intensity_Post, which is the intensity of light at point 919b between the three-wavelength band 903c, is smaller than Intensity_Pre. As a result, light 903 having a higher color reproduction is emitted. Intensity_Post denotes a minimum value among the intensities of light distributed between the second wavelength band 903b and the third wavelength band 903c.

In FIG. 9, the relationship of the intensities of light in the respective regions is expressed by Equation (2).

&Quot; (2) &quot;

Intensity_B <Intensity_Pre

Intensity_Post <Intensity_Pre

In summary, the light incident on the light absorbing sheet 930 in the light source unit 910 according to an embodiment of the present invention includes the first wavelength band 901a, the second wavelength band 901b, the third wavelength band 901c, Where light of a wavelength band that is the boundary between the second wavelength band 901b and the third wavelength band 901c is absorbed by the light absorbing sheet 930. [

Conventionally, in the light source part, there is a part of light even in the wavelength band separating between green and red so that the distribution of the color conversion factor such as the fluorescent material is reduced to prevent the color mixture, and the intensity of the green and red is low. However, when the present invention is applied, the distribution of the color conversion factors is increased so that the green and red colors are expressed sufficiently in the light source unit 910, and the light that occurs at the boundary portion between green and red due to the increase of the color conversion factors Since the light absorbing sheet 930 can absorb light of a specific wavelength band, not only blue but also green and red colors can be reproduced. Particularly, the light-absorbing sheet 930 and the color conversion factor are not complicated in process but their process cost is also low, so that not only efficiency of color reproducibility but also efficiency in process and price is high.

9, a light source unit 910 that emits light divided into a first wavelength band 901a, a second wavelength band 901b, and a third wavelength band 901c, a second wavelength band 901b, The backlight unit can be constituted by the light absorbing sheet 930 that absorbs light at the boundary of the third wavelength band 901c. Of course, various components such as a light guide plate and a reflection plate can be disposed in the backlight unit.

The light absorbing sheet 930 absorbs the light at the boundary between the second wavelength band 901b and the third wavelength band 901c in the light having the same characteristic as the 901 and transmits the green light and the green light corresponding to the second wavelength band 901b It is possible to prevent the color mixture between the red light corresponding to the three-wavelength band 901c. A yellow color conversion factor and a red color conversion factor are used to indicate the green and red colors of the light source unit 910 using the blue LED and the second wavelength band 903b and the third wavelength band 903c, the intensity of the green and red light can be increased by absorbing the light in the wavelength band of the boundary.

The characteristics of the light 901 incident on the light absorbing sheet 930 described above, that is, the characteristics of the light 901 emitted from the light source portion 910 and the characteristics of the light 903 emitted from the light absorbing sheet 930 As follows. Intensity_Pre, which is the minimum value of the Intensity value of the wavelength band disposed between the second wavelength band 901b and the third wavelength band 901c of the incident light 901, is the second wavelength band emitted from the light- (Intensity_Post), which is the minimum value of intensity values of the wavelength bands arranged between the third wavelength band 903b and the third wavelength band 903c.

Absorbing sheet 930 absorbs light between the second wavelength band 901b and the third wavelength band 901c so that the light source unit 910 can increase the intensity of green and red, To enhance light efficiency and color reproduction rate.

2, the light absorbing sheet 930 may be in close contact with any one of the DBEF 210 and the prism sheet 220 as shown in FIG. The order of the DBEF, the prism sheet, and the light absorbing sheet can be variously configured.

In an embodiment of the present invention, when the blue LED is used as one embodiment of the light source units 110, 810, and 910, the distribution of the yellow and red color conversion factors is increased. As a result, the color coordinates of the light source units 110, 810, and 910 to which the embodiment of the present invention is applied can satisfy Wx0.293 / Wy0.240. Also, when the embodiment of the present invention is applied, the color temperature can reach 10,000K.

1, an embodiment of the present invention is applicable to both the edge method and the direct method. Further, in the present invention, the material properties of the light absorbing layer included in the light absorbing sheets 830 and 930 can be considered. When the light absorbing material is weak to heat, it is applied in an edge manner, have.

According to an embodiment of the present invention, there is provided a light emitting device including a light source portion 910 for emitting light in three divided wavelength bands, a light absorbing sheet 910 for absorbing light in a weak boundary portion and converting the light into white light of three divided wavelength bands, (930) may be implemented.

The light source and the light absorbing sheet shown in Figs. 8 and 9 can be applied to the backlight unit of Fig. 1 and the liquid crystal display device of Fig.

For example, the liquid crystal display device 50 may include a backlight unit 100a or 100b, a liquid crystal display panel 90, and a frame 80 for supporting the backlight unit 100a or 100b. The backlight unit 100a or 100b includes a light source unit that emits light divided into a first wavelength band and a second wavelength band and a light absorbing sheet that absorbs light of a partial wavelength band of the second wavelength band, And outputs the light divided into the first wavelength band and the second wavelength band that are incident on the first wavelength band, the second-first wavelength band, and the second-second wavelength band. In addition, the liquid crystal display panel 90 displays images using light in the first wavelength band, the second-first wavelength band, and the second-second wavelength band. As described above, since the liquid crystal display panel 90 displays an image using white light, the red and green are enhanced by using the light source and the light absorbing sheet as described above, thereby increasing the color reproduction rate and increasing the DCI overlap rate by 95% or more have. Since the backlight unit that increases the light efficiency and the DCI superposition ratio is used, the power consumption of the liquid crystal display device 50 can be lowered, and in particular, the color reproducibility in a large-area TV can be improved.

8 and 9, the characteristic of the light source unit of the backlight unit of the present invention is that Intensity_GR, which is the minimum value of the intensity of light in the second wavelength band, is the first wavelength band and the second wavelength And emits light having a spectrum larger than Intensity_B, which is the minimum value of the intensity of light at the band boundary. The light absorbing sheet of the backlight unit of the present invention absorbs light between the second-1 wavelength band and the second-2 wavelength band described above and absorbs light between the 2-1 wavelength band and the 2-2 wavelength band Intensity_GR_post (Intensity_Post in FIG. 9) which is the minimum value of Intensity has a value smaller than Intensity_GR (Intensity_Pre in FIG. 9). For example, a yellow color conversion factor and a red color conversion factor are used to indicate green and red in a light source section using a blue LED, and the second-1 wavelength band and the second-2 wavelength band are separated The intensity of the green and red light can be increased by absorbing the light in the wavelength band of the boundary so that the liquid crystal display of the present invention can express green and red in depth.

The optical sheet previously described with reference to FIG. 2 includes a DBEF 210, a prism sheet 220, and a light absorbing sheet 230. The configuration of these sheets can be variously selected. Hereinafter, the structure of the light-absorbing sheet and other sheets according to an embodiment of the present invention will be described with reference to FIG.

10 is a view showing a configuration of an optical sheet including a light absorbing sheet according to an embodiment of the present invention.

1010 denotes a DBEF, 1020a and 1020b denote a prism sheet, and 1030 denote a light absorbing sheet. The laminated structure of the first light absorbing sheet 1051 is the order of the light absorbing sheet 1030, the DBEF 1010, the first prism sheet 1020a, and the second prism sheet 1020b. In the same configuration as 1051, the DCI overlap ratio is 95% or more.

The laminated structure of the second light absorbing sheet 1052 is the order of the light absorbing sheet 1030, the first prism sheet 1020a and the second prism sheet 1020b, and the DCI overlap ratio is also 95% or more. The laminated structure of the third light absorbing sheet 1053 is the order of the DBEF 1010, the light absorbing sheet 1030, the first prism sheet 1020a, and the second prism sheet 1020b. On the other hand, the laminated structure of the fourth light-absorbing sheet 1054 is the order of the DBEF 1010, the light-absorbing sheet 1030, and the prism sheet 1020.

In addition, the DBEF 1030, the light absorbing sheet 1030, and the prism sheet 1020 may be stacked in various order, and the optical sheet may overlap two or more specific sheets according to the embodiment. Since the DBEF 1030 and the prism sheet 1020 are components for improving brightness, the light efficiency can be increased when the light absorbing sheet 1030 and the light absorbing sheet 1030 are closely contacted with each other to form a backlight unit. In particular, if the light efficiency is increased, the life of the light source part can be increased and the power consumption can be reduced.

11 is a view showing a configuration of a light-absorbing sheet 1030 according to an embodiment of the present invention. As shown in FIG. 3, the light absorbing sheet 1030 may have a light absorbing layer on a lower or upper layer of a base PET film, a base PC film (Base Polycarbonate Film), a base PS film (Base PolyStyrene Film) . A light absorbing layer is produced by laminating or coating a base film to produce a light absorbing sheet.

More specifically, in the case of the first light-absorbing sheet 1030a, the light-absorbing layer 300 is disposed under the base film 1031. In the case of the second light absorbing sheet 1030b, the light absorbing layer 300 is disposed on the base film 1031. In the third light absorbing sheet 1030c, light absorbing layers 300a and 300b are disposed on the upper and lower layers of the base film 1031 to increase the light absorbing efficiency.

3, 4, and 11, the light absorbing sheet may be configured such that a light absorbing layer is disposed on one side or both sides of the prism sheet. Further, as shown in 1053 and 1054 in Fig. 10 or 150 in Fig. 2, the light absorbing sheet can be disposed between the double brightness improving film and the prism sheet. Further, the light absorbing sheet may be disposed on one side of the double brightness enhancement film as shown in 1051 in Fig. Or the light absorbing sheet may be disposed on one side of the prism sheet as shown at 1052 in Fig.

12 is a diagram showing DCI superposition degree when one embodiment of the present invention is applied. In the color coordinates 1210 indicates the DCI reference value. The case where the backlight unit of the present invention is applied is the same as 1220. The overlapped ratio corresponds to 95% or more, and the high color reproduction rate is high.

In the past, when the white light was implemented only by the color conversion factor, the DCI overlap ratio was only 81%. However, when the present invention is applied, the color conversion factor is adjusted to the blue LED and the light absorption sheet is combined. A new light source having a narrow band width can be realized.

Further, when the embodiment of the present invention is applied, high color reproduction is possible without using an expensive optical sheet. In particular, by combining the light absorbing sheet, which is an embodiment of the present invention, with the light source unit, each color has a narrow bandwidth, so that the color can be expressed in depth. The light emitted from the light source portion can be configured to absorb the overlapping region of the light absorbing sheet, that is, the overlapped wavelength band (for example, a part of the wavelength band around 590 nm) corresponding to the characteristic of overlapping of green and red .

On the other hand, the light-absorbing sheet of the present invention has an advantage that it does not deteriorate the light efficiency based on a configuration that does not contain harmful substances in the environment.

When the present invention is applied, it is possible to realize a differentiated high color reproduction technique by utilizing a new LAS (Light Absorption Sheet) containing a light absorbent capable of absorbing only a specific wavelength. Particularly, by combining the color conversion factors to the light source portion to increase the color of the red / blue portion, the light absorption sheet is combined to narrow the bandwidth of blue, green, and red to emit clear and clean white light, (For example, a DCI overlap ratio of 95%), it is possible to reduce the cost of manufacturing the light source portion.

A liquid crystal display device according to an embodiment of the present invention includes a backlight unit including a light absorbing sheet that absorbs light in a boundary region between green and red, and a liquid crystal display unit that displays an image using white light emitted from the backlight unit. And a display panel. In more detail, a backlight unit that absorbs light of a specific wavelength band using a light absorbing sheet and emits R / G / B in a narrow bandwidth without separating wavelengths of R, G, and B in the light source, A display device can be implemented.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is therefore to be understood that such changes and modifications are intended to be included within the scope of the present invention unless they depart from the scope of the present invention.

50: liquid crystal display device 90: liquid crystal display panel
100a, 100b: backlight unit 150, 1051, 1052, 1053, 1054:
210, 1010: DBEF 220, 1020. 1020a, 1020b: prism sheet
230, 830, 930: light absorbing sheet 300: light absorbing layer
710, 810, 910:

Claims (8)

A light source unit emitting light divided into a first wavelength band and a second wavelength band; And
And a light absorbing sheet for absorbing light of a partial wavelength band of the second wavelength band and outputting the light as light classified into a first wavelength band, a second-first wavelength band and a second-second wavelength band.
The method according to claim 1,
The backlight unit
Further comprising at least one of a dual brightness enhancement film or a prism sheet,
Wherein the double brightness enhancement film or prism sheet and the light absorbing sheet are in close contact with each other.
3. The method of claim 2,
The light-absorbing sheet has a light absorbing layer disposed on one side or both sides of the prism sheet,
Wherein the light absorbing sheet is disposed between the double brightness enhancement film and the prism sheet or disposed on one side of the double brightness enhancement film or on one side of the prism sheet.
The method according to claim 1,
Wherein the first wavelength band corresponds to a blue wavelength band,
The second-1 wavelength band corresponds to a green wavelength band,
And the second-2 wavelength band corresponds to a red wavelength band.
The method according to claim 1,
And the light absorbing sheet absorbs light between the second-1 wavelength band and the second-2 wavelength band.
The method according to claim 1,
The light source unit includes at least one blue LED (Light Emitting Diode), a yellow color conversion factor and a red color conversion factor,
Intensity_GR which is a minimum intensity of light in the second wavelength band is larger than Intensity_B which is a minimum intensity of light of the first wavelength band and the second wavelength band boundary.
A first wavelength band, a second wavelength band and a second wavelength band by absorbing light in a part of the wavelength band of the second wavelength band, A backlight unit including a light absorbing sheet for emitting light as light divided into a plurality of light beams;
A liquid crystal display panel for displaying an image using light of the first wavelength band, the second-first wavelength band, and the second-second wavelength band; And
And a frame supporting the backlight unit and the liquid crystal display panel.
8. The method of claim 7,
Intensity_GR, which is the minimum intensity of light in the second wavelength band, is greater than Intensity_B, which is the minimum intensity of light of the first wavelength band and the second wavelength band boundary,
The light absorbing sheet absorbs light between the second-1 wavelength band and the second-2 wavelength band, and absorbs light between the second-1 wavelength band and the second- The Intensity_GR_post being smaller than the Intensity_GR.

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