KR20120108479A - Backlight unit - Google Patents

Abstract

PURPOSE: A backlight unit is provided to install a first lenticular lens array sheet on an upper portion of an optical waveguide wherein the first lenticular lens array sheet forms parallel light, thereby increasing light transmission efficiency. CONSTITUTION: An optical waveguide array(100) comprises a plurality of optical waveguides. The optical waveguides respectively correspond to lower pixels of liquid crystals. The optical waveguides induce light of three colors irradiated from three color light sources by internal total reflection. The optical waveguides are vertically branched toward the lower pixels of the liquid crystals. A first lenticular lens array sheet(400) is arranged between an upper portion of the optical waveguide array and a liquid crystal panel. The first lenticular lens array sheet converts the light of three colors into parallel light. [Reference numerals] (AA,DD) Red light; (BB,EE) Green light; (CC,FF) Blue light

Description

BACKLIGHT UNIT [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit (BLU) of a liquid crystal display (LCD), and more particularly, to a backlight unit capable of improving light efficiency of a liquid crystal display (LCD).

In general, a liquid crystal display (LCD) uses a change in the transmittance of a liquid crystal according to an applied voltage to convert light into various pieces of electrical information generated by various devices into image information and light to the liquid crystal panel. It consists of a backlight unit for supplying.

1A is a cross-sectional view showing an example of a conventional direct type liquid crystal display device.

Referring to the drawings, a conventional liquid crystal display (LCD) includes a liquid crystal panel 20 including a liquid crystal pixel 23 that serves as a light valve by controlling light transmittance, and supplies light to the liquid crystal panel 20. The backlight unit 10 is provided.

The backlight unit 10 includes a CCFL (Cold Cathode Fluorescence Lamp) 11a, or EEFL (External Electrode Fluorescence Lamp), or a white light LED (Light Emitting Diode), or an LED that emits three colors of R, G, and B. The light source assembly 11 and the light sheets reflecting or evenly mixing the light emitted from the light source from the reflector 11b positioned below the light source are scattered to the plurality of liquid crystal pixels 23. Here, R, G, and B are abbreviations for Red, Green, and Blue, and R, G, and B mean red, green, and blue without further indication.

The light sheet is basically composed of a diffusion plate 12, a diffusion sheet 13, a light collecting sheet 14, a reflective polarizing sheet 15, a protective film 16 and the like to properly adjust the viewing angle and brightness. do.

1B illustrates a liquid crystal display device employing a side type backlight unit. In the case of the side type backlight unit, the optical waveguide 17 includes a light source of the CCFL or LED 11-1 disposed on the side surface of the optical waveguide 17. Like the direct type, a diffusion sheet 13, a light collecting sheet 14, a reflective polarizing sheet 15, and a protective film 16 are disposed between the optical waveguide 17 and the liquid crystal panel 20. A scattering pattern 18 and a reflective film 19 are provided on the lower surface of the waveguide 17 to improve uniformity and brightness of light.

As shown in FIG. 1 and FIG. 2, the liquid crystal panel 20 is provided between the rear glass substrate 22, the front glass substrate 25, the rear glass substrate 22, and the front glass substrate 25. A plurality of liquid crystal pixels 23, R, G and B color filters 24 installed inside the front glass substrate 25, a polarizing sheet A 21 attached to the rear glass substrate 22, and a front glass substrate ( The polarizing sheet B 26 attached to 25 and the like play a major optical role. Each of the liquid crystal pixels 23 is composed of R, G, and B liquid crystal subpixels for implementing R, G, and B three-color images. Each of the R, G, and B liquid crystal subpixels has R, G, and B liquid crystal subpixels. R, G, and B color filters 24 (24a, 24b, 24c) that transmit B light are provided.

In addition, a black matrix (24d) is provided at the boundary line between adjacent color filters 24 to remove color crosstalk between neighboring subpixels.

In the conventional LCD as described above, a method of implementing a color image includes installing R, G, and B liquid crystal subpixels that implement an image of three colors R, G, and B in one liquid crystal pixel that is the minimum unit of the pixel. R, G, B color filters are installed on the front side of the liquid crystal subpixel of the backlight unit, and the backlight unit scatters uniform white light over the entire liquid crystal panel, by passing only the R, G, and B light for each subpixel. Color image is made.

In conventional LCDs, the power of white light emitted from the backlight unit 10 is controlled by the aperture ratios of the polarizing sheets 21 and 26, the color filters 24, and the liquid crystal pixels 23 provided in front and behind the liquid crystal pixels 23. Is mostly lost and only about 5% to 10% of the light exits the LCD, so the optical energy efficiency of the LCD has been significantly lower. Therefore, improving the optical energy efficiency of the LCD is an important task for enhancing the competitiveness and energy saving of the LCD. The optical energy loss of the LCD is about 50% in the polarizing sheets 21 and 26, about 30% to 50% in the aperture ratio of the liquid crystal pixel 23, and about 70% in the color filter 24, so that the overall light is about 90% or more. Loss occurs and causes high power consumption of LCD. In particular, the color filter 24 is a core element for implementing a color image, but has a problem of causing a lot of light loss due to absorption.

The color filter 24 is a key element for implementing a color image, but since white light passes through the color filter 24, about 30% is transmitted and about 70% is absorbed and lost. Account for the largest portion of losses.

Because of such a problem, one of the technologies being developed to increase the optical energy efficiency of the LCD is the FSC (Field Sequential Color) technology. This technology is designed to eliminate the color filter which occupies a large part of the optical energy loss. It uses R, G, and B three-color LEDs as the light source for the backlight, and the screen image signal is a three-color image of R, G, and B colors. After separating into signals, R video signal is sent to the liquid crystal panel while the R-LED is turned on, G video signal is sent to the liquid crystal panel while the G-LED is turned on, and B video signal is sequentially sent to the liquid crystal panel while the B-LED is turned on. It is a technology that allows the viewer to feel the color image by spraying at a high speed.

The FSC LCD technology has achieved considerable advances through many studies due to the need for no liquid crystal subpixels and greatly improved light transmission efficiency, but the speed of a circuit for controlling an image is weaker than that of a basic LCD. It should be about 6 times, and there are problems such as flickering and color break-up of moving images.

In order to solve the above problems, the applicant of the present invention has applied for a "liquid crystal display without color filter" (Registration No. 10-0962302), but the liquid crystal display without color filter improves light transmission efficiency by removing the color filter. An optical waveguide having a cylindrical shape (Cylindrical Shape) has been introduced, but an optical waveguide having such a cylindrical shape has a problem in that it is not easy to manufacture. In addition, the optical structure such as a prism type optical branch structure having a very narrow width is too complicated to have practical problems, and also has a problem in that application is difficult.

The present invention uses an optical waveguide or a thin film type self-luminous source that induces light by the total internal reflection effect, which is easy to manufacture and simple in structure, and efficiently, and installs a first lenticular lens array sheet to create parallel light on the upper part of the optical waveguide. Accordingly, an object of the present invention is to provide a backlight unit of a liquid crystal display device which improves light transmission efficiency by installing a reflective polarizing film between a first lenticular lens array sheet and an optical waveguide array.

According to an aspect of the present invention, disposed below the liquid crystal panel including a plurality of liquid crystal subpixels respectively corresponding to the three colors of light to irradiate three colors of light, three colors of light to implement a color image A plurality of three color light sources each irradiated; Installed to correspond to the plurality of liquid crystal subpixels installed in the liquid crystal panel, and arranged side by side to vertically branch toward the plurality of liquid crystal subpixels while guiding the three colors of light emitted from the three color light sources through the internal reflection. An optical waveguide array having a plurality of optical waveguides; And a first lenticular lens array sheet disposed between an upper portion of the optical waveguide array and the liquid crystal panel and converting three colors of light emitted from the three color light sources into parallel light.

According to yet another aspect of the present invention, a plurality of liquid crystals disposed in the liquid crystal panel are disposed below the liquid crystal panel including a plurality of liquid crystal subpixels respectively corresponding to three colors of light, and irradiate three colors of light. A three-color self-emitting source array having a plurality of three-color self-emitting sources disposed to be parallel to each other so as to correspond to the lower pixels, and to emit three-color light toward the plurality of liquid crystal sub-pixels; And a first lenticular lens array sheet disposed between the three-color self-emitting source array and the liquid crystal panel and converting three colors of light emitted from the three-color self-emissive light source into parallel light. have.

The backlight unit according to the present invention has the following effects.

First, the liquid crystal display is provided through a backlight unit that directly sprays red, green, and blue light to the liquid crystal subpixels corresponding to red, green, and blue colors, respectively, using optical waveguides corresponding to the red, green, and blue light sources. The light transmission efficiency of the device can be improved.

Second, it is easy to manufacture by using the optical waveguide and the first lenticular lens array sheet of a simple structure, and R, G, B by providing a second lenticular lens array sheet between the liquid crystal panel and the first lenticular lens array sheet Differentiated condensation of red, green, and blue can be achieved into the liquid crystal subpixel.

Third, by using the R, G, B LED and the R, G, B light mixer, it is possible to achieve stable and high image quality by supplying uniform and stable red, green, and blue light.

Fourth, by using self-emitting sources such as R, G, B OLED or R, G, B quantum dots instead of LEDs as a three-color light source, the structure of the light source is simplified, and the advantages of the liquid crystal display device and the advantages of the self-emitting source By utilizing all of these, high efficiency and image quality can be achieved.

Fifth, the polarization efficiency may be improved by disposing the reflective polarizing film between the first lenticular lens array sheet and the optical waveguide array, thereby further improving the light efficiency of the liquid crystal display device.

Sixth, R, G, and B color filters are supplied to the R, G, and B liquid crystal subpixels, respectively, so that the R, G, and B color filters can be removed, and the color filter can be stabilized to reduce color crosstalk and stabilize image quality. You can keep it without removing it.

1A is a structural diagram illustrating an example of a conventional direct type liquid crystal display.
1B is a structural diagram showing an example of a liquid crystal display device employing a conventional side type backlight unit.
2 is a plan view showing the structure of a general color filter.
3A is a structural diagram illustrating a liquid crystal display device to which a backlight unit according to a first embodiment of the present invention is applied.
3B is a perspective view illustrating a structure of the backlight unit illustrated in FIG. 3A.
4A is a perspective view illustrating a state in which a slit sheet is integrally installed on a lower surface of the first lenticular lens array sheet.
4B is a perspective view showing a state in which the slit sheet is integrally installed on the upper part of the optical waveguide.
4C is a perspective view illustrating a slit sheet provided between the first lenticular lens array sheet and the optical waveguide array.
FIG. 5 is a layout view showing the arrangement of the three-color light source, the optical fiber array, the optical mixer, and the optical waveguide array shown in FIG. 3.
6 is a view showing a state in which the optical fiber output terminal shown in Figure 3 is fixed by the optical fiber stator.
FIG. 7 is a conceptual diagram illustrating an optical connection state of the three-color light source, the optical fiber array, the optical mixer, and the optical waveguide array shown in FIG. 3.
8 is a structural diagram illustrating a liquid crystal display device to which a reflective polarizing film is applied to a backlight unit according to a first embodiment of the present invention.
9 is a principle diagram illustrating a principle of light passing through the first lenticular lens array sheet of FIG. 8.
FIG. 10 is a side cross-sectional view of the liquid crystal display of FIG. 8.
11A to 11C are perspective views illustrating embodiments of the optical waveguide shown in FIG. 8, respectively.
12 is a structural diagram illustrating a liquid crystal display device to which a backlight unit according to a second embodiment of the present invention is applied.
FIG. 13 is a diagram illustrating a state in which three color light sources are regionally divided according to an embodiment of the present invention.
14 is a diagram illustrating a result detected by an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention, and not all of the technical ideas of the present invention are described. Therefore, It is to be understood that equivalents and modifications are possible.

Hereinafter, a backlight unit according to the present invention will be described with reference to the accompanying drawings.

3 to 11C, the liquid crystal display device to which the backlight unit 300 is applied according to an embodiment of the present invention includes a three-color light source 310, an optical waveguide array 100, and a first lenticular lens array. A sheet 400.

The backlight unit 300 is disposed under the liquid crystal panel 200 including the plurality of liquid crystal subpixels 210 corresponding to the three color light sources 310, respectively, and the three colors emitted from the three color light sources 310. Serves to irradiate light to the liquid crystal panel 200.

Here, the three colors of light generally mean red (R; red), green (G; green), and blue (B; blue) for implementing a color image. However, since cyan, magenta, and yellow can also implement color images, the three colors of light may be cyan, magenta, and yellow. However, hereinafter, for convenience of description, the three colors of light will be described as red (R), green (G), and blue (B) by way of example, which is not to be interpreted as narrowing the scope of the present invention. Should not.

The liquid crystal panel 200 disposed on the backlight unit 300 includes a plurality of liquid crystal subpixels 210; 210R, 210G, respectively corresponding to three colors of light R, G, and B of red, green, and blue. 210B) and polarizing films 240 and 250 and a diffusion sheet 260.

The backlight unit 300 disposed below the liquid crystal panel 200 may include a plurality of three colors that irradiate three colors of red, green, and blue colors R, G, and B, respectively, constituting three primary colors of light. Light sources 310; 310R, 310G, and 310B. As the three-color light source 310, a light emitting diode (LED) emitting light of red, green, and blue, respectively, or a white light emitted from a white LED using a spectroscopic element such as a diffraction grating. It can also be obtained by spectroscopically decomposing into red, green and blue light. Alternatively, the three color light source 310 may use an organic light emitting diode (OLED) or a quantum dot.

The optical waveguide array 100 includes a plurality of optical waveguides 110 (110R, 110G, 110B) disposed in parallel with each other. Each optical waveguide 110 (110; 110R, 110G, 110B) is installed to correspond to a plurality of R, G, B liquid crystal subpixels 210 installed in the liquid crystal panel 200, respectively, irradiated from the three-color light source 310 And an optical branching structure that splits the three colors of light R, G, and B toward the liquid crystal subpixel 210 corresponding to each color.

A first lenticular lens array sheet 400 is disposed between the upper portion of the optical waveguide array 100 and the liquid crystal panel 200, and the first lenticular lens array sheet 400 is formed by the three-color light source 310. It serves to convert the irradiated three-color light (R, G, B) into parallel light, respectively.

As shown in FIGS. 3 and 4C, the first lenticular lens array sheet 400 may include a reflective light blocking layer 410, a slit 420, a transparent substrate 430, and a lenticular lens array 440. Include.

The reflective light shielding layer 410 serves to block or reflect the light guided by the optical waveguide 110, and the slit 420 passes the light that is retained by the optical waveguide 110 and the transparent substrate. 430 serves to transfer the light passing through the slit 420 to the top.

와 같이 주어진다. 따라서 슬릿의 폭 W가 작을수록 평행도가 우수해진다. 여기서, n은 상기 투명기판(430)과 상기 렌티큘러렌즈 어레이(440)의 굴절율이다. 상기 렌티큘러렌즈 어레이(440)의 초점거리 f는 상기 슬릿(420)의 상을 상기 액정하위픽셀(210)에 맺도록 설계될 수 있다.The lenticular lens array 440 refracts the light passing through the slit 420 and the transparent substrate 430 and transmits the light to the liquid crystal panel 200 in a vertical direction. The parallelism of the parallel light generated by the lenticular lens array 440 is proportional to the width W of the slit 420 divided by the focal length f of the lenticular lens array 440.

As shown in Fig. Therefore, the smaller the width W of the slit, the better the parallelism. N is a refractive index of the transparent substrate 430 and the lenticular lens array 440. The focal length f of the lenticular lens array 440 may be designed to couple the image of the slit 420 to the liquid crystal subpixel 210.

The first lenticular lens array sheet 400 includes a plurality of light blocking walls 450 between the lenticular lenses 440 to minimize color crosstalk of light of different colors between adjacent liquid crystal subpixels. Can be installed additionally. When the light shielding wall 450 is installed, color interference between neighboring liquid crystal subpixels is almost eliminated, and thus, the price competitiveness can be improved by removing a color filter from the liquid crystal panel. The light blocking wall 450 is disposed between the lenticular lenses 440 adjacent to each other in a longitudinal direction parallel to the lenticular lens 440 in a direction perpendicular to the plane.

The light passing through the liquid crystal subpixels 210R, 210G, and 210B passes through the polarizing film 250 attached to the outside of the front glass substrate 925 and is then diffused by the diffusion sheet 260 to form an appropriate brightness and viewing angle. Done. The diffusion sheet 260 may be manufactured using a micro lens array sheet, a micro lenticular lens array sheet, or a transparent resin coated sheet including beads. Alternatively, a scattering pattern or a groove may be installed on the surface to diffuse light, and another optical sheet including a function capable of diffusing other light is possible.

As shown in FIG. 4A, the reflective light shielding layer 410 is provided on the lower surface of the first lenticular lens array sheet 400 or integrally installed on the upper surface of the optical waveguide 110 as shown in FIG. 4B. As shown in FIG. 4C, a slit sheet 480 having a slit 470 may be installed between the first lenticular lens array sheet 400 and the optical waveguide array 100. The reflective light shielding layers 410 described in FIGS. 4A-4C are all identical in optical performance. When the reflective light shielding layer 410 is installed in the slit sheet 480, any slit 420 or the reflective light shielding layer may be formed on the lower surface of the first lenticular lens array sheet 400 and the upper surface of the optical waveguide 110. 410 need not be formed. The slit sheet 480 reflects the light and the slit 470 through which light formed in parallel with the lenticular lens array 440 of the optical waveguide array 100 and the first lenticular lens array sheet 400 passes. It is composed of a reflective surface 460 for blocking.

As shown in FIG. 5, the backlight unit 300 uses red, green, and blue tricolor lights R, G, and B emitted from the plurality of tricolor sources 310 by total internal reflection and light propagation effects. A plurality of light mixers 600 may be further provided by uniformly mixing each color to evenly distribute the respective R, G, and B optical waveguides 110 for each color. The light mixer 600 may be made of a transparent material and may have a structure in which light is uniformly mixed by total internal reflection such as a cylindrical, square pillar, and polygonal pillar structure. The optical mixer 600 may be applied to realize stable and excellent image quality by averaging brightness differences and wavelength differences of individual LEDs, and also for illuminating a plurality of liquid crystal subpixels 210 using a few LEDs. Also advantageous.

In addition, the liquid crystal display device may further include an optical fiber array 500. The optical fiber array 500 includes a plurality of optical fibers 510 (510R, 510G, 510B). Each of the optical fibers 510; 510R, 510G, and 510B receives the red, green, and blue three-colored lights R, G, and B emitted from the three-color light sources 310 corresponding to each color, respectively. 3) to each optical waveguide 110 (110; 110R, 110G, and 110B).

The optical mixer 600 is preferably installed between the inlet end of the optical fibers 510 (510R, 510G, 510B) of the optical fiber array 500 and the three-color light source 310. The optical mixer 600 (600; 600R, 600G, 600B) installed as described above uniformly mixes red, green, and blue light (R, G, B) from the plurality of three-color light sources (310) for each of the plurality of optical fibers. And distributes evenly toward 510. In order to increase the light input efficiency, the light input surface 640 and the light output surface 650 of the light mixer 600 may be subjected to an anti-reflective coating.

The optical fiber 510 disposed in front of the light output surface of the optical mixer 600 may be arranged in one dimension, that is, in one line, or two or three or more lines in two dimensions. In addition, in order to minimize the loss of light, the optical fibers 510 should be arranged as close to each other as possible.

Although not shown, the optical fiber 510 may be a branched optical fiber having one input terminal and a plurality of output terminals. When dividing one optical fiber 510 into a plurality of optical fibers, the diameter of the optical fiber disposed in front of the optical output surface of the optical mixer 600 may be larger than the width of the optical waveguide 110. However, even in this case, the diameter of the end of the optical fiber 510 branched into the optical waveguide 110 into the optical waveguide 110 must be smaller than the width of the input end of the optical waveguide 110 to reduce the optical coupling loss. It can increase. The method of splitting the optical fiber may be divided into branches from the optical fiber having one input terminal and have a plurality of output terminals, and the intensity of light from the multiple output terminals should be the same.

The backlight unit 300, the back plate 700 to install the optical waveguide 110, the three-color light source 310 and the optical fiber 510 of the optical fiber array 500 of the optical waveguide array 100. It may be further provided. The back plate 700 fixes the optical waveguide 110 of the optical waveguide array 100 and the optical fiber 510 of the optical fiber array 500 on the upper surface thereof, and the tricolor light source 310 on the rear or side surface thereof. And a light mixer 600 to be arranged, and the optical fiber 510 is optically connected to supply the light between the three-color light source 310 and the light mixer 600 and the optical waveguide 110.

In FIG. 5, the optical waveguide array 100, the optical waveguide 110, and the backlight unit 300 are not illustrated, and the optical waveguide array 100, the optical waveguide 110, and the backlight unit 300 are not shown. Reference will be made to FIG. 3.

Referring to FIG. 6, the back plate 700 includes an optical fiber stator 710 to fix the exit end of the optical fiber 510 of the optical fiber array 500 at the inlet of the optical waveguide 110 (see FIG. 3). To this end, a plurality of optical fiber stators 710 are provided on the rear plate 700. The structure of the optical fiber stator 710 may be a quadrangle or a triangle, and any structure may be used to stably fix the optical fiber 510 so that the optical fiber 510 does not shake.

The operation of the liquid crystal display device to which the backlight unit 300 according to the first embodiment of the present invention described above will be described with reference to FIG. 7. Here, red (R), green (G), and blue (B) LEDs may be used as the three-color light source 310. Since the principles of implementing the LEDs having different colors are the same, the description of For convenience, the operation according to the first embodiment of the present invention will be described using the red light emitted from the red LED.

The red light from the plurality of R-LEDs 310R installed at the bottom of the back plate 700 enters the light input surface 640 of the light mixer 600 and is evenly mixed and then comes out of the light output surface 650. Into the R-optical fiber 510R. In this case, by using the optical mixer 600, the light entering the optical fiber 510 can be uniformly distributed, and the optical characteristics are averaged by averaging the optical characteristics such as brightness difference, wavelength difference, and life variation difference of each LED. It can improve performance.

The red light induced by total internal reflection in the R-optical fiber 510R enters into the R-waveguide 110R installed at the upper portion of the back plate 700, and again in total internal reflection in the R-waveguide 110R. The red light guided by the light is branched vertically by the optical branch structure 115 inside the R-waveguide 110R and incident into the plurality of R-liquid crystal subpixels 210R of the liquid crystal panel 200.

In the same way, the light from the G-LED 310G is mixed in the G-optical mixer 600G, and then guided into the G-waveguide 110G via the G-optic fiber 510G to form a G-liquid crystal subpixel. Incidentally, the light emitted from the B-LED 310B enters the B-liquid crystal subpixel 210B through the same process.

As described above, the red, green, and blue light emitted from the R, G, and B-LEDs 310R, 310G, and 310B are respectively arranged in the order of the optical mixers 600, R, G, and B-optical fibers as shown in FIG. 510R, 510G, 510B), R, G, and B-waveguides (110R, 110G, 110B) through sequentially entering the R, G, B-liquid crystal subpixels (210R, 210G, 210B) to implement a color image have. In addition, since the light branched from the R, G, B-waveguides (110R, 110G, 110B) directly enters the R, G, B-liquid crystal subpixels (210R, 210G, 210B), the diffusion sheet, Various light sheets such as prism sheets are also unnecessary.

In FIG. 7, the liquid crystal panel 200 and the plurality of liquid crystal subpixels 210; 201R, 210G, and 210B are not shown. The liquid crystal panel 200 and the plurality of liquid crystal subpixels 210; 201R and 210G are not shown. 210B) may be preferably referred to in FIG.

8 to 11C, the reflective polarizing film 800 is further provided in the liquid crystal display device to which the backlight 300 according to the first embodiment of the present invention is applied.

8 is a structural diagram showing a state in which the reflective polarizing film 800 is further provided in the liquid crystal display device to which the backlight unit 300 according to the first embodiment of the present invention is applied. However, since the same reference numerals as the reference numerals shown in FIGS. 3 to 7 denote the same members having the same configuration and having the same function, the repeated description will be omitted.

The backlight unit 300 may further include a reflective polarizing film 800 to improve light efficiency. Here, the backlight unit 300 may include both the reflective polarizing film 800 and the second lenticular lens array sheet 900 or only one of them. In addition, the second lenticular lens array sheet 900 may be attached to the polarizing film 240 attached to the rear glass substrate 900 of the liquid crystal panel 200, or may be integrally formed with the first lenticular lens array sheet 400. It may be manufactured.

The reflective polarizing film 800 is provided between the optical waveguide 110 of the optical waveguide array 100 and the first lenticular lens array sheet 400 to improve the light efficiency of the backlight unit 300. . The reflective polarizing film 800 is separately installed between the first lenticular lens array sheet 400 and the optical waveguide 110, or integrally installed on the bottom surface of the first lenticular lens array sheet 400, or the optical waveguide It can be integrally installed on the top surface of 110, and in all cases the optical performance is almost similar. In addition, the reflective polarizing film 800 may be integrally installed with the reflective light shielding layer 410 or the slit sheet 480.

The second lenticular lens array sheet 900 enhances the performance of the first lenticular lens array sheet 400 and condenses light into the liquid crystal subpixel 210 to increase efficiency. Each lenticular lens 910 included in the second lenticular lens array sheet 900 is disposed at the same interval as the optical waveguides 110R, 110G, and 110B and the liquid crystal subpixel 210. Each of the lenticular lenses 910 has a convex shape and is provided on an upper surface of the lenticular lens 440 of the first lenticular lens array sheet 400. In addition, the second lenticular lens array sheet 900 may be attached to the polarizing film 240 attached to the rear glass substrate 922 of the liquid crystal panel 200.

The optical waveguide array 100 may further include an optical waveguide substrate 120 for branching light corresponding to each color. The optical waveguide substrate 120 is disposed below each optical waveguide 110.

The optical waveguide substrate 120 has a higher optical refractive index and better surface planarity than the material constituting each optical waveguide 110 in case the roughness or the optical characteristic of the surface of the back plate 700 is inappropriate for the waveguide of the light. It is preferable to be made of a material or a metal or metal thin film such as aluminum, silver, copper or gold having high reflectance in the visible light region, or a multilayer thin film having high visible light reflectance.

Hereinafter, the operation of the liquid crystal display device to which the backlight unit 300 in which the reflective polarizing film 800 is additionally installed will be described. Here, the repeated description of the content duplicated with the content described in the first embodiment of the present invention will be omitted. In addition, it will be described using the red light emitted from the red (R) LED for convenience of description.

As illustrated in FIGS. 9 to 10, the red light R guided along the R-optical fiber 510R is transferred into the R-waveguide 110R installed on the top of the back plate 700, and R- Reflective polarization film 800 formed on the upper part of the red light (R) is induced by the total internal reflection into the optical waveguide (110R) is partially branched by the optical branch structure 115 installed inside the R-waveguide (110R) And passes through the first lenticular lens array sheet 400 into the R-liquid crystal subpixel 210R.

Non-polarized light (p, s) that proceeds in the R-optical fiber (510R) is scattered in the optical branch structure 115 in the optical waveguide proceeds to the top, but the liquid crystal in the reflective polarizing film 800 The p-polarized light coinciding with the transmission polarization axis of the polarization film 240 of the panel 200 is transmitted, and the s polarization perpendicular to the transmission polarization axis is reflected. The p-polarized light passing through the reflective polarizing film 800 passes through the slit 420 at the lower surface of the first lenticular lens array sheet 900 to become parallel light by the lenticular lens array 440 thereon. The narrower the width W of the slit 420, the better the parallelism. When the reflected s-polarized light proceeds inside the optical waveguide 110 and the polarized light changes to become p-polarized light, the s-polarized light passes through the reflective polarizing film 800 and proceeds to the liquid crystal subpixel 210.

The light hitting the reflective light shielding layer 410 of the first lenticular lens array sheet 400 reflects all irrespective of the polarization state, returns to the R-waveguide 110R, and recycles to the slit while recycling. And then proceeds to the first lenticular lens array sheet 400 to increase the light efficiency.

The reflective light shielding layer 410 is provided on a lower surface of the first lenticular lens array sheet 400, or integrally provided on an upper surface of the optical waveguide 110, or between the first lenticular lens array sheet and the optical waveguide array. It may be installed in the form of a slit sheet 480 having a slit separately, all the optical performance is the same.

Meanwhile, the light passing through the liquid crystal subpixels 210R, 210G, and 210B passes through the polarizing film 250 attached to the outside of the front glass substrate 925, and is then diffused by the diffusion sheet 260 to provide an appropriate brightness and viewing angle. To form. The diffusion sheet 260 may be manufactured using a micro lens array sheet, a micro lenticular lens array sheet, or a transparent resin coated sheet including beads. Alternatively, scattering patterns or grooves may be provided on the surface to diffuse light, and other optical sheets including a function of diffusing light may be provided.

Referring to FIG. 10, after the light emitted from the optical fiber 510 is incident into the optical waveguide 110, the light is transmitted to the first lenticular lens array sheet 400 by the optical branch structure 115 installed inside the optical waveguide 110. ) Principle of separation in the direction of. The optical branch structure 115 provided on the lower surface of the optical waveguide 110 is an optical waveguide by providing a micro optical structure such as a micro cylindrical structure, a micro lens structure, a prism structure, a groove structure, or a scattering pattern. Light propagating inside 110 is scattered by the micro-optical structure 115 so that light is branched upward. At this time, by increasing the density of the micro optical branch structure 115 along the direction of light propagation can be made uniform along the optical waveguide 110.

11A to 11C, the cross-sectional structure of the optical waveguide 110 should be a structure capable of inducing light in the optical waveguide by the total internal reflection effect of the light, and the cross section of the light incident portion has a square structure 110. 11A), hemispherical structures 110 '(see FIG. 11B), trapezoidal structures 110 "(see FIG. 11C) are possible.

Hereinafter, a liquid crystal display device to which the backlight unit 300 according to the second embodiment of the present invention is applied will be described.

12 is a structural diagram illustrating a backlight unit 300 according to a second embodiment of the present invention. However, the same reference numerals as the reference numerals shown in FIGS. 3 to 11 denote the same members having the same structure and the same function, and thus, repeated descriptions thereof will be omitted.

As shown in FIG. 12, the backlight unit 300 according to the third embodiment of the present invention includes a tricolor self-emitting source array 150 and a first lenticular lens array sheet 400. In addition, the reflective polarizing film 800 and the second lenticular lens array sheet 900 may be further provided.

The liquid crystal panel 200 installed on the backlight unit 300 includes a plurality of liquid crystal subpixels 210 (210; 210R, 210G, and 210B) respectively corresponding to three colors of light (R, G, and B).

The backlight unit 300 is disposed under the liquid crystal panel 200 and includes a plurality of three-color self-luminous sources 150 (150; 150R, 150G, and 150B) for emitting three colors of light (R, G, and B). do. As the three-color self-emitting source 150, red, green, and blue organic light emitting diodes (OLEDs) 150 or red, green, and blue quantum dots may be used. Quantum dot self-luminous sources are semiconductor crystals (eg, CdS, CdSe, ZnS, etc.) having a diameter of about 10 nanometers, and a polymer may be coated on the outer layer. It can generate light and can be used as the tricolor self-luminous source of the present invention together with OLED.

The three color self-emitting source arrays 150 (150R, 150G, 150B) are installed at the same interval as the plurality of liquid crystal subpixels (210; 210R, 210G, 210B), and the three color self-emitting source arrays 150 are It is provided on the top of the back plate 700.

The first lenticular lens array sheet 400 includes a reflective light shielding layer 410, a slit 420, a transparent substrate 430, and a lenticular lens array 440. Due to the provision, color interference between neighboring pixels can be prevented. When the light shielding wall 450 is added between the lenticular lenses 440, color interference is almost eliminated, thereby making it possible to remove the color filter. In addition, the reflective light shielding layer 410 is provided between the first lenticular lens array sheet 400 and the three-color self-emitting source array 150 as a separate slit sheet 480 or the three-color self-emitting source 150. It may be installed integrally on the upper surface of the. Since the first lenticular lens array sheet 400 has been described in the first embodiment of the present invention, a detailed description thereof will be omitted.

The R, G, and B color filters 920 installed in the liquid crystal panel 200 may be removed, but may be left as it is to minimize screen stability and color interference. That is, the color filter 920 is not necessarily provided, but may be selectively provided.

The second lenticular lens array sheet 900 further improves efficiency by condensing three colors of light R, G, and B into the liquid crystal subpixels 210, 210R, 210G, and 210B and the color filter 920. Optionally, additional installation is possible.

The second lenticular lens array sheet 900 is installed between the liquid crystal panel 200 and the first lenticular lens array sheet 400, and the second lenticular lens array sheet 900 is the liquid crystal panel 200. And a plurality of lenticular lenses 910 disposed to correspond to the liquid crystal subpixel 210. Since the second lenticular lens array sheet 900 has been described in the first embodiment of the present invention, a detailed description thereof will be omitted.

The reflective polarizing film 800 may be disposed between the first lenticular lens array sheet 400 and the three-color self-luminous sources 150R, 150G, and 150B of the three-color self-luminous source array 150. The reflective polarizing film 800 may be integrally formed with the reflective light blocking layer 410 or the slit sheet 480.

Fig. 13 shows a planar layout view of the three-color self-luminous sources. Since a plurality of three-color self-emitting sources 150 are provided on the rear panel 700, it is possible to apply a local dimming technology for applying ON / OFF power in units of compartments. By increasing the contrast, it is possible to further reduce the power consumption. As shown in FIG. 13, the unit of regional division driving is driven by the block 990, and the minimum unit of the block is up to one linear self-luminous source. As the unit of the block 990 is smaller, better image quality can be realized.

Therefore, the light energy efficiency can be greatly improved by spraying three colors of light onto the liquid crystal subpixels 210 corresponding to the three colors by using the self-luminous sources corresponding to the three colors. In addition, the light is easily collected by using the first lenticular lens array sheet 400, and the second lenticular lens array sheet 900 is provided between the liquid crystal panel 200 and the first lenticular lens array sheet 400. The light efficiency can be further improved. In addition, by using the self-luminous source as a three-color light source, it is possible to manufacture a more simple and efficient backlight unit 300 by removing optical components such as the optical fiber array 510 and the light mixer 600 applied in the first embodiment.

In the second embodiment in which the self-luminous sources 150R, 150G, 150B of the self-luminous source array 150 are used as three-color light sources instead of the LEDs, the optical power between the individual LEDs appearing when a plurality of LEDs are adopted as the light source. There is no characteristic variation, and many thin film transistors (TFT) required for each pixel are unnecessary in an AMOLED (Active-Matrix OLED) display using OLED directly as a pixel without the liquid crystal panel 200. This is highlighted.

FIG. 14 shows the results of an optical simulation conducted to prove the validity of the present invention, and is parallel to the R, G, B liquid crystal subpixels 210R, 210G. 210B at the point where the liquid crystal subpixel 210 is located. The R, G, B lines are formed to show that the R, G, B light is incident into the R, G, B liquid crystal subpixels 210R, 210G. 210B, and the high efficiency of the present application is justified.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: optical waveguide array 110: optical waveguide
200: liquid crystal panel 210: liquid crystal subpixel
300: backlight unit 310: three-color light source
400: first lenticular lens array sheet 410: reflective light shielding layer
420: slit 430: transparent substrate
440 lenticular lens array 450 shading wall
480: slit sheet 500: optical fiber array
510: optical fiber 600: optical mixer
700: rear panel 710: optical fiber stator
800: reflective polarizing film 900: second lenticular lens array sheet
910: Lenticular Lens

Claims (25)

It is disposed under the liquid crystal panel including a plurality of liquid crystal subpixels respectively corresponding to three colors of light to irradiate three colors of light,
A plurality of three-color light source for irradiating three colors of light to implement a color image;
Installed to correspond to the plurality of liquid crystal subpixels installed in the liquid crystal panel, and arranged side by side to vertically branch toward the plurality of liquid crystal subpixels while guiding the three colors of light emitted from the three color light sources through the internal reflection. An optical waveguide array having a plurality of optical waveguides; And
And a first lenticular lens array sheet disposed between an upper portion of the optical waveguide array and the liquid crystal panel to convert light of three colors irradiated from the three color light sources into parallel light.
The method according to claim 1,
The three color light source,
Red, green, and blue light emitting diodes (LEDs) emitting red, green, and blue, respectively, constituting the three primary colors of light,
Red, green, and blue light obtained by spectroscopic white light emitted from a white LED using a spectroscopic element,
Red, green, and blue organic light emitting diodes (OLEDs) emitting red, green, and blue, respectively;
The backlight unit is any one selected from quantum dots emitting red, green, and blue, respectively.
The method according to claim 1,
The first lenticular lens array sheet,
A reflective light shielding layer having slits for reflecting or passing the light branched from the optical waveguide;
A transparent substrate for transmitting the light passing through the slit to the top;
And a lenticular lens array having a plurality of lenticular lenses that refract light passing through the slit and the transparent substrate to be transmitted to the liquid crystal panel.
The method according to claim 3,
The first lenticular lens array sheet,
And a plurality of light blocking walls respectively disposed in a vertical direction between the plurality of lenticular lenses to remove color interference between the lenticular lens and the liquid crystal subpixels adjacent to each other.
The method according to claim 1,
And a slit sheet disposed between the first lenticular lens array sheet and the optical waveguide array to selectively reflect or pass light.
The method according to claim 1,
The optical waveguide array,
And a slit disposed on an upper surface of the plurality of optical waveguides to selectively reflect or pass light.
The method according to claim 1,
Each optical waveguide,
The cross section of the light incident portion is a shape selected from one of rectangular, hemispherical, elliptical and trapezoidal,
The backlight unit is a straight line in the longitudinal direction.
The method according to claim 1,
And a plurality of optical fiber arrays having a plurality of optical fibers for transmitting the three colors of light emitted from the three color light sources to the respective optical waveguides of the optical waveguide array in correspondence with each color.
The method according to claim 8,
Each of the optical fibers has a branch type having a single input terminal and a plurality of output terminals.
The method according to claim 8,
A plurality of light mixers installed at each of the optical fiber inlet ends and uniformly mixing the three colors of light irradiated from the plurality of three color light sources for each color to distribute the light evenly toward the respective optical fibers;
And a backplane having a top surface fixed to each optical fiber of the optical fiber array and the optical waveguide array.
The method of claim 10,
The light mixer is a backlight unit of the selected shape of the cylindrical, rectangular columnar and polygonal columnar.
The method of claim 10,
The backplane,
And a plurality of optical fiber stators for fixing an exit end of each optical fiber of the optical fiber array.
The method according to claim 1,
And a reflective polarizing film disposed between the optical waveguide array and the first lenticular lens array sheet to improve light efficiency.
The method according to claim 13,
The reflective polarizing film is integrated with the first lenticular lens array sheet or the optical waveguide array backlight unit.
The method according to any one of claims 1 to 14,
A second lenticular lens array sheet disposed between the first lenticular lens array sheet and the liquid crystal panel, the second lenticular lens array sheet including a plurality of lenticular lenses disposed to correspond to the liquid crystal subpixels, and easily condensing to the liquid crystal subpixels. Further comprising a backlight unit.
The method according to claim 15,
The second lenticular lens array sheet,
And a backlight unit integrated with the liquid crystal panel or the first lenticular lens array sheet.
It is disposed under the liquid crystal panel including a plurality of liquid crystal subpixels respectively corresponding to three colors of light to irradiate three colors of light,
A three-color self-emitting source array having a plurality of three-color self-luminous sources arranged in parallel with each other so as to correspond to the plurality of liquid crystal subpixels provided in the liquid crystal panel, and arranged in parallel with each other to radiate three-color light toward the plurality of liquid crystal subpixels; And
And a first lenticular lens array sheet disposed between the three-color self-emitting source array and the liquid crystal panel to convert three colors of light emitted from the three-color self-emitting source into parallel light.
18. The method of claim 17,
The three-color self-luminous source,
OLEDs emitting red, green, and blue, respectively
The backlight unit is any one selected from quantum dots emitting red, green, and blue, respectively.
18. The method of claim 17,
A second lenticular lens array sheet disposed between the liquid crystal panel and the first lenticular lens array sheet, the second lenticular lens array sheet including a plurality of lenticular lenses disposed to correspond to the liquid crystal subpixels, and easily condensing to the liquid crystal subpixels. Further comprising a backlight unit.
18. The method of claim 17,
The first lenticular lens array sheet,
A reflection light shielding layer formed with a slit for reflecting or passing the light emitted from the three color light emitting sources;
A transparent substrate for transmitting the light passing through the slit to the top;
And a lenticular lens array having a plurality of lenticular lenses that refract light passing through the slit and the transparent substrate to be transmitted to the liquid crystal panel.
The method of claim 20,
The first lenticular lens array sheet,
And a plurality of light blocking walls respectively disposed in a vertical direction between the plurality of lenticular lenses to remove color interference between the lenticular lens and the liquid crystal subpixels adjacent to each other.
18. The method of claim 17,
And a slit sheet disposed between the first lenticular lens array sheet and the tricolor self-luminous source array to selectively reflect or pass light.
18. The method of claim 17,
And a reflective polarizing film disposed between the first lenticular lens array sheet and the three-color self-emitting source array to improve light efficiency.
24. The method of claim 23,
The reflective polarizing film is integral with the reflective light blocking layer or the slit sheet.
18. The method of claim 17,
The three-color self-emitting source array,
And a slit disposed on the plurality of three-color self-luminous sources to selectively reflect or pass light.

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