Abstract:
Provided is a display apparatus including: a display panel; and a backlight unit configured to output light to the display panel, wherein the backlight unit includes: a light source configured to emit light having a particular color; a light guide plate (LGP) configured to scatter the light incident from the light source and configured to emit the scattered light through a light emitting surface; and an optical converter configured to convert the light emitted from the light source and including an optical conversion pattern disposed on an inner side from the display panel, the optical converter including an optical conversion material for converting color of light; and wherein the optical converter is provided at an edge portion of the backlight unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Korean Patent Application No. 2015-0045048, filed on Mar. 31, 2015 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Apparatuses and methods consistent with exemplary embodiments relate to a display apparatus, and more particularly, to a display apparatus that is capable of improving color uniformity. 
         [0004]    2. Description of the Related Art 
         [0005]    In the related art, display apparatuses are apparatuses for displaying images, such as televisions (TVs) or monitors. 
         [0006]    For example, display apparatuses are apparatuses for displaying broadcasting signals or image data having various formats by including display panels on which images are displayed. 
         [0007]    The display panels described above may be classified into emissive display panels that emit light by themselves and nonemissive display panels that do not emit light by themselves. Examples of emissive display panels include, but not limited to, cathode ray tube (CRT) panels, electro luminescence (EL) panels, organic light emitting diode (OLED) panels, vacuum fluorescence display (VFD) panels, field emission display (FED) panels, and plasma display panels (PDPs). Examples of nonemissive display panels include, but are not limited to, liquid crystal display (LCD) panels. LCD panels and PDPs have been recently widely used. 
         [0008]    An LCD panel includes a backlight unit which emits white light and a display panel which transmits or blocks light emitted from the backlight unit. 
         [0009]    In particular, it is imperative that the LCD panel has uniform brightness and uniform tone throughout the entire surface of the LCD panel. To this end, the backlight unit has to emit light having uniform brightness and uniform tone throughout the entire surface of the backlight unit. 
         [0010]    However, due to a structural difference between an edge portion and a center portion of the backlight unit, there is a difference between brightness and tone of light emitted from the edge portion and brightness and tone of light emitted from the center portion. 
         [0011]    Also, a larger amount of light is generated in a direction of an optical axis of the backlight unit, whereas a relatively small amount of light is generated in a lateral direction of the backlight unit. Thus, color uniformity and brightness uniformity may be diminished. 
       SUMMARY 
       [0012]    Aspects of one or more exemplary embodiments provide a display apparatus that is capable of improving color uniformity by correcting colors of reflected lights emitted from light sources disposed at edge portions of a backlight unit. 
         [0013]    In accordance with an aspect of an exemplary embodiment, there is provided a display apparatus including: a display panel; and a backlight unit that outputs light to the display panel, wherein the backlight unit may include: light sources disposed to emit light having a particular color; a light guide plate (LGP) that scatters light incident from the light sources and emits the scattered light through an emitting surface; and an optical converter disposed to convert light emitted from the light sources, and the optical converter may be disposed at edge portions of the backlight unit and may include an optical conversion material for converting color of light and optical conversion patterns disposed on the LOP. 
         [0014]    The optical conversion material may include a fluorescent material. 
         [0015]    The backlight unit may include a mold frame disposed to support the display panel, and the optical converter may be disposed on an inner surface of the mold frame. 
         [0016]    The mold frame may include: a front surface disposed so that the display panel is supported on the front surface; and a rear surface in which an installation groove for installing the optical converter is formed. 
         [0017]    The optical conversion patterns may include one among a circular shape, an oval shape, a rectangular shape, and a polygonal shape. 
         [0018]    The optical conversion patterns may be formed on a rear surface of the LOP. 
         [0019]    The backlight unit may further include a quantum dot sheet disposed to convert light emitted toward a front surface of the LOP. 
         [0020]    Densities of the optical conversion patterns may be formed by a difference between the edge portions and a center portion of the LOP. 
         [0021]    Densities of the optical conversion patterns may be reduced as the optical conversion patterns get closer to a center of the LGP from ends of the LOP. 
         [0022]    In accordance with an aspect of another exemplary embodiment, there is provided a display apparatus includes: a display panel on which an image is formed; light sources disposed to emit light having one among red, green, and blue colors toward the display panel; a light guide plate (LGP) that scatters light incident from the light sources and emits the scattered light through an emitting surface; a mold frame disposed to support the display panel; a reflector member that reflects light leaking toward an outside of the LGP in a direction of the LGP; and an optical converter disposed to convert light emitted from the light sources, wherein the optical converter may be disposed on the mold frame and may include an optical conversion material for converting color of light and optical conversion patterns disposed on the LOP. 
         [0023]    The optical conversion material may include a fluorescent material. 
         [0024]    The optical conversion patterns may be formed on a rear surface of the LOP. 
         [0025]    Densities of the optical conversion patterns may be formed by a difference between edge portions and a center portion of the LOP. 
         [0026]    Densities of the optical conversion patterns may be reduced as the optical conversion patterns get closer to a center of the LGP from ends of the LOP. 
         [0027]    In accordance with still an aspect of another exemplary embodiment, there is provided a display apparatus including: a display panel on which an image is formed; light sources disposed to emit light having a particular color; a light guide plate (LGP) that scatters light incident from the light sources and emits the scattered light in a direction of the display panel; a quantum dot sheet that converts light emitted toward a front surface of the LGP; a mold frame disposed to support the display panel; and an optical converter disposed to convert light emitted from the light sources, wherein the optical converter may be disposed on the mold frame and may include an optical conversion material for converting color of light and optical conversion patterns disposed on the LOP. 
         [0028]    The optical conversion patterns may be formed on a rear surface of the LOP. 
         [0029]    The light sources may include one among red, green, and blue colors. 
         [0030]    The optical converter may include a yellow fluorescent material for converting blue light into white light. 
         [0031]    Densities of the optical conversion patterns may be formed by a difference between edge portions and a center portion of the LOP. 
         [0032]    Densities of the optical conversion patterns may be reduced as the optical conversion patterns get closer to a center of the LGP from ends of the LOP. 
         [0033]    In accordance with an aspect of another exemplary embodiment, there is provided a display apparatus including: a display panel; and a backlight unit configured to output light to the display panel, wherein the backlight unit includes: a light source configured to emit light having a particular color; a light guide plate (LGP) configured to scatter the light incident from the light source and configured to emit the scattered light through a light emitting surface; and an optical converter configured to convert the light emitted from the light source and including an optical conversion pattern disposed on an inner side from the display panel, the optical converter made of an optical conversion material for converting color of light; and wherein the optical converter is provided at an edge portion of the backlight unit. 
         [0034]    The backlight unit may include a mold frame configured to support the display panel, and the optical converter may be disposed on at least one of an inner surface of the mold frame or an inner surface of the LOP. 
         [0035]    The mold frame may include: a front surface on which the display panel is supported; and a rear surface including an installation groove, the optical converter provided in the installation groove. 
         [0036]    The optical conversion pattern may include at least one of a circular shape, an oval shape, a rectangular shape, and a polygonal shape. 
         [0037]    The optical conversion pattern may be provided on a rear surface of the LOP. 
         [0038]    The backlight unit may further include a quantum dot sheet configured to convert the light emitted from the light emitting surface of the LOP. 
         [0039]    The optical conversion pattern may include a plurality of optical conversion patterns and density of the optical conversion patterns is formed based on a position of each optical conversion pattern of the plurality of optical conversion patterns with respect to the edge portion and a center portion of the LOP. 
         [0040]    The optical conversion pattern may include a plurality of optical conversion patterns and density of the plurality of optical conversion patterns is decreased toward a center portion of the LGP from the edge portion of the LOP. 
         [0041]    In accordance with an aspect of another exemplary embodiment, there is provided a display apparatus including: a display panel configured to form an image; a light source configured to emit light having at least one of red, green, and blue colors toward the display panel; a light guide plate (LGP) configured to scatter the light incident from the light source and configured to emit the scattered light through a light emitting surface; a mold frame supporting the display panel; a reflector member configured to reflect light leaking out of the LGP in a direction of the LGP; and an optical converter configured to convert the light emitted from the light source, wherein the optical converter is disposed on the mold frame or the LGP, includes an optical conversion pattern and is made up of an optical conversion material for converting color of light. 
         [0042]    In accordance with an aspect of another exemplary embodiment, there is provided a display apparatus including: a display panel configured to form an image; a light source configured to emit light having a particular color; a light guide plate (LGP) configured to scatter the light incident from the light source and configured to emit the scattered light in a direction of the display panel; a quantum dot sheet configured to convert the light emitted from a light emitting surface of the LGP; a mold frame supporting the display panel; and an optical converter configured to convert the light emitted from the light source, wherein the optical converter is provided on at least one of the mold frame and the LGP and includes an optical conversion pattern and is made up of an optical conversion material for converting color of light. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0043]    The above and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings of which: 
           [0044]      FIG. 1  is a perspective view of a display apparatus according to an exemplary embodiment; 
           [0045]      FIG. 2  is an exploded perspective view of the display apparatus according to an exemplary embodiment; 
           [0046]      FIG. 3  is a cross-sectional view taken along line A-A′ of  FIG. 1  according to an exemplary embodiment; 
           [0047]      FIG. 4  is a schematic view of a light guide plate (LGP) having an optical converter of a display apparatus according to an exemplary embodiment; 
           [0048]      FIG. 5  is an enlarged view of portion B of  FIG. 4  according to an exemplary embodiment; 
           [0049]      FIG. 6  is a schematic view of an LGP having an optical converter of a display apparatus according to still an exemplary embodiment; and 
           [0050]      FIG. 7  is a schematic view of an LGP having an optical converter of a display apparatus according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0051]    Embodiments described in the specification and configurations shown in the drawings of the specification are merely exemplary embodiments of the disclosure, and there may be various modified examples that may replace the embodiments and the drawings of the specification at the time of filing an application of the disclosure. Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. Meanwhile, terms “front end”, “rear end”, “upper portion”, “lower portion”, “top end”, and “bottom end” used in the following description are defined based on the drawings. A shape and a position of each of elements are not limited by the terms. 
         [0052]      FIG. 1  is a perspective view of a display apparatus according to an exemplary embodiment, and  FIG. 2  is an exploded perspective view of the display apparatus according to an exemplary embodiment, and  FIG. 3  is a cross-sectional view taken along line A-A′ of  FIG. 1  according to an exemplary embodiment. 
         [0053]    A display apparatus  1  is an apparatus that may process image signals received from the outside and may visually display a processed image from the received image signals. Hereinafter, the display apparatus  1  is a television (TV). However, the exemplary embodiment is not limited thereto. For example, the display apparatus  1  may be implemented to have various forms including a monitor, a portable multimedia device, and a portable communication device. Any display apparatus that is capable of visually displays an image may be used as the display apparatus  1 , and the form of the display apparatus is not particularly limited. 
         [0054]    As illustrated in  FIGS. 1 through 3 , the display apparatus  1  includes a display panel  10  on which image information is displayed, and a case  2  that is disposed at an outside area of the display panel  10  so as to accommodate the display panel  10  and various components in the display apparatus  1 . Also, a backlight unit (BLU)  50  and an optical member  30  are disposed in the case  2 . 
         [0055]    The case  2  is formed to surround edge portions and a rear surface of the display panel  10 . A stand  3  for installing the display apparatus  1  on an installation surface (not shown), such as on the bottom, is disposed at a lower portion of the case  2 . 
         [0056]    Meanwhile, although not shown, the display apparatus  1  according to the exemplary embodiment may also be fixed onto a wall using a wall-hanger bracket installed on the wall, instead of the stand  3 . In the exemplary embodiment, the wall-hanger bracket may also be separably installed at the case  2  or fixed onto the wall using the case  2 . 
         [0057]    Referring to  FIGS. 2 and 3 , a top chassis  11  disposed on a front surface of the display panel  10  to form a front edge of the display apparatus  1 , a bottom chassis  12  disposed on a rear surface of the display panel  10 , and a mold frame  40  disposed in the display apparatus  1  may be disposed in front of the case  2 . 
         [0058]    The top chassis  11  is formed to have a shape of a rectangular ring and is disposed on the same surface as a surface on which the display panel  10  on which an image is displayed, is disposed, so that edge portions of the display panel  10  are not exposed to the outside. 
         [0059]    The bottom chassis  12  may be disposed on an opposite surface to the surface on which the display panel  10  is disposed. The bottom chassis  12  may be disposed to prevent various components included in the display apparatus  1  from being exposed to the outside and to protect various components included in the display apparatus  1  from an external shock. 
         [0060]    The mold frame  40  is disposed to support the display panel  10 , the optical member  30 , and the backlight unit  50 . The mold frame  40  is disposed to fix the display panel  10 , the optical member  30 , and the backlight unit  50  to the top chassis  11  and the bottom chassis  12 . 
         [0061]    The display panel  10  may display various images according to image signals input from the outside. In the exemplary embodiment, the display panel  10  may be an emissive display panel on which a plurality of pixels that constitute the display panel  10  generate light by themselves so that an image can be generated, or a nonemissive display panel on which the plurality of pixels reflect/transmit/block light so that an image can be generated. 
         [0062]    Hereinafter, the display panel  10  will be described on the assumption that the display panel  10  is a nonemissive display panel on which the plurality of pixels reflect/transmit/block light emitted from the backlight unit  50  so that an image can be generated. 
         [0063]    The display panel  10  may include a liquid crystal layer (not shown), a transparent electrode layer (not shown), a transparent substrate (not shown), and a color filter array (not shown). 
         [0064]    An appropriate amount of liquid crystal is prepared in the liquid crystal layer. Here, the liquid crystal means an intermediate state of crystal and liquid. The liquid crystal represents an optical property according to a change in a voltage. For example, a direction of the arrangement of molecules that constitute the liquid crystal may be changed according to a change in an electric field applied to the liquid crystal. 
         [0065]    A pair of transparent electrode layers are disposed at both sides of the liquid crystal layer so as to form the changed electric field in the liquid crystal layer. The electric field applied to the liquid crystal layer is changed according to a voltage input between the pair of transparent electrode layers. 
         [0066]    The transparent electrode layer may include gate lines (not shown), data lines (not shown), and a thin film transistor (TFT). 
         [0067]    The gate lines are disposed in a row direction to turn on or off the TFT according to gate signals, and the data lines are disposed in a column direction to transmit data signals to the plurality of pixels through the TFT. In this way, the electric field applied to the liquid crystal layer is changed according to the gate signals input through the gate lines and the data signals input through the data lines, and the molecular arrangement of the liquid crystal is changed according to the change in the electric field. Also, the liquid crystal layer transmits or blocks light according to the molecular arrangement of the liquid crystal. 
         [0068]    The gate lines and the data lines may be formed of indium tin oxide (ITO) or indium zinc oxide (IZO). 
         [0069]    A pair of transparent substrates (not shown) constitute an exterior of the display panel  10  and protect the liquid crystal layer and the transparent electrode layer. The pair of transparent substrates may be formed of reinforced glass having good light transmittance or a transparent film. 
         [0070]    The color filter array may include a red filter, a blue filter, and a green filter, which are respectively formed in each of regions corresponding to a plurality of pixels so that colors can be displayed in the plurality of pixels that constitute the display panel  10 . 
         [0071]    In this way, the display panel  10  blocks or transmits light generated in the backlight unit  50  that will be described later so that an image can be generated. In detail, the respective pixels that constitute the display panel  10  block or transmit light emitted from the backlight unit  50  so that images having various colors can be generated. 
         [0072]    A driving circuit  20  provides driving signals for driving the display panel  10  to the display panel  10 . The driving circuit  20  may include a data driving circuit  21  and a gate driving circuit  22 . 
         [0073]    The gate driving circuit  22  may be connected to the gate lines (not shown) of the display panel  10  and may transmit the gate signals to the gate lines. Also, the data driving circuit  21  may be connected to the data lines (not shown) of the display panel  10  and may transmit the data signals to the data lines. 
         [0074]    The backlight unit  50  is installed in rear of the display panel  10  and generates light through which the display panel  10  generates an image. 
         [0075]    The backlight unit  50  includes a plurality of light sources  51  disposed to emit light toward the display panel  10 , a light guide plate (LGP)  60  that converts light generated in each of the plurality of light sources  51  into sheet light, a reflector sheet  35  that is disposed on a rear surface of the LGP  60  and reflects light output from the LGP  60 , and a quantum dot sheet  37  that receives the light from the LGP  60  and outputs white light (light in which lights having various colors are mixed with each other). 
         [0076]    The plurality of light sources  51  are disposed at sides of the LGP  60  and output light toward the LGP  60 , as illustrated in  FIG. 3 . 
         [0077]    In the exemplary embodiment, the plurality of light sources  51  may output light (monochromatic light) having one wavelength (one color) or light (white light) in which lights having a plurality of wavelengths are mixed with each other. 
         [0078]    When the backlight unit  50  includes the quantum dot sheet  37 , a plurality of light sources that output monochromatic light (in particular, blue light having a short wavelength) are usually used as the plurality of light sources  51 . Hereinafter, the exemplary embodiments where the plurality of light sources  51  output blue light (hereinafter, referred to as “blue light”) will be described. 
         [0079]    The plurality of light sources  51  may employ light emitting diodes (LEDs) having a small heat dissipation amount or cold cathode fluorescence lamps (CCFLs). 
         [0080]    The plurality of light sources  51  may be coupled to a printed circuit board (PCB)  52  formed of a flexible material and may be disposed at the edge portions of the display panel  10 . 
         [0081]    The LGP  60  changes a proceeding direction of light incident from sides of the edge type backlight unit  50  and emits light toward a front surface  61  of the LGP  60 . In the exemplary embodiment, in order to change the proceeding direction of light, a plurality of convex striped patterns may be formed in the front surface  61  of the LGP  60 , and a plurality of dots may be formed in a rear surface  62  of the LGP  60 . 
         [0082]    Also, the sizes of the convex striped patterns and a distance therebetween may be adjusted so that uniform light can be emitted toward the front surface  61  of the LGP  60 , and the sizes of the plurality of dots and a distance therebetween may be adjusted. 
         [0083]    In addition, the convex striped patterns in the front surface  61  of the LGP  60  may be formed in an embossed shape using a printing technique, and the dots in the rear surface  62  of the LGP  60  may be formed in an engraved shape using laser. 
         [0084]    Thus, a part of light incident on an inside of the LGP  60  may be scattered by the dots formed in the rear surface  62  of the LGP  60  and may be emitted toward the front surface  61  of the LGP  60 . 
         [0085]    Also, the remaining part of the light may be reflected by the reflector sheet  35  disposed on the rear surface  62  of the LGP  60  toward the inside of the LGP  60 . 
         [0086]    In addition, a part of the reflected light may move to a center of the LGP  60 , may be scattered in the center of the LGP  60 , and may also be emitted toward the front surface  61  of the LGP  60 . 
         [0087]    In this way, due to refraction, reflection and scattering of the light generated in the LGP  60 , the LGP  60  is disposed to emit uniform light toward the front surface  61  of the LGP  60 . 
         [0088]    The LGP  60  may employ polymethyl methacrylate (PMMA) or transparent polycarbonate (PC) that is transparent and has good strength. 
         [0089]    The reflector sheet  35  is disposed on the rear surface  62  of the LGP  60  described above and reflects a part of light directed toward the rear surface  62  of the LGP  60  from the inside of the LGP  60  toward the inside of the LGP  60 . 
         [0090]    The reflector sheet  35  is manufactured by coating base materials with a material having high reflectivity. For example, the reflector sheet  35  may be manufactured by coating base materials, such as polyethylene terephthalate (PET), with a polymer having high reflectivity. 
         [0091]    In addition, the quantum dot sheet  37  may be disposed on the front surface  61  of the LGP  60 . 
         [0092]    The quantum dot sheet  37  converts light emitted toward the front surface  61  of the LGP  60  into white light. 
         [0093]    Quantum dots mean semiconductor particles having a small spherical shape with a size of nanometer (nm) and may include a central body having a size of approximately 2 to 10 nm and a shell formed of zinc sulfide (ZnS). Here, cadmium selenite (CdSe), cadmium tellurite (CdTe), or cadmium sulfide (CdS) may be used to form the central body of the quantum dots. 
         [0094]    The quantum dots emit light by themselves or emit light having a particular wavelength by absorbing light when a voltage is applied to the quantum dots. 
         [0095]    Electrons of the quantum dots are placed at a low energy level (or band) in a stable state. In this case, when the quantum dots absorb light from the outside, electrons at the low energy level move to a high energy level (or band). Since electrons placed at the high energy level are in an instable state, the electrons naturally move to the low energy level from the high energy level. In this way, while the electrons move to the low energy level from the high energy level, the electrons emit light corresponding to an energy difference between the high energy level and the low energy level. In this case, a wavelength of the emitted light is determined by the energy difference between the high energy level and the low energy level. 
         [0096]    In particular, the quantum dots emit light having a short wavelength as their sizes are decreased, and the quantum dots emit light having a long wavelength as their sizes are increased. For example, quantum dots having a diameter of approximately 2 nm may emit blue light, and quantum dots having a diameter of approximately 10 nm may emit red light. 
         [0097]    Also, by using the quantum dots having various sizes, the quantum dots may emit lights having various wavelengths from the red light to the blue light. In other words, by using the quantum dots having various sizes, light (white light) having a natural color may be generated. 
         [0098]    The quantum dot sheet  37  may be manufactured by dispersing the above-described quantum dots into a resin. 
         [0099]    When light is incident onto the quantum dot sheet  37  from the LGP  60 , the incident light excites electrons of the quantum dots included in the quantum dot sheet  37 . In other words, electrons at the low energy level (or band) move to the high energy level (or band) due to the incident light. 
         [0100]    Subsequently, the quantum dots output light (white light) having various wavelengths according to their sizes while the excited electrons move to the low energy level from the high energy level. The light having various wavelengths passes through the optical member  30  and the display panel  10  so that an image can be generated. 
         [0101]    As described above, the backlight unit  50  may include the plurality of light sources  51 , the LGP  60 , the reflector sheet  35 , and the quantum dot sheet  37 , thereby emitting uniform sheet light. 
         [0102]    The optical member  30  refracts or scatters light so as to increase a viewing angle of the display apparatus  1  and to increase brightness of the display apparatus  1 . 
         [0103]    The optical member  30  may include various sheets. For example, the optical member  30  may include a diffusion sheet  31 , a prism sheet  32 , a protective sheet  33 , and a dual brightness-enhancement film (DBEF)  34 . 
         [0104]    The diffusion sheet  31  diffuses light emitted from the backlight unit  50  along a surface so that color and brightness of the entire screen of the display apparatus  1  become uniform. Since light emitted from the LGP  60  is emitted through the patterns formed in the front surface  61  of the LGP  60 , the patterns formed in the front surface  61  of the LGP  60  may be recognized from the light emitted from the LGP  60 . 
         [0105]    In order to prevent the patterns formed in the front surface  61  of the LGP  60  from being recognized from the light emitted from the LGP  60 , the diffusion sheet  31  may diffuse the light emitted from the LGP  60  in a direction perpendicular to an emitting direction. 
         [0106]    In other words, the diffusion sheet  31  diffuses the light emitted from the backlight unit  50  so that brightness of the entire surface of the display apparatus  1  can be maintained at a uniform level. 
         [0107]    The light that passes through the diffusion sheet  31  is diffused in a direction perpendicular to a surface of the diffusion sheet  31  such that brightness of the display apparatus  1  is rapidly lowered. The prism sheet  32  refracts or concentrates the light diffused by the diffusion sheet  31 , thereby increasing brightness of the display apparatus  1 . 
         [0108]    Also, the prism sheet  32  includes prism patterns having the shape of a triangular prism. A plurality of prism patterns are arranged to be adjacent to each other and constitute the shape of a plurality of bands. That is, the plurality of prism patterns that are patterns in which crests and valleys are arranged in a staggered manner, form rows and protrude toward the display panel  10 . 
         [0109]    The protective sheet  33  protects various components included in the backlight unit  50  from an external shock or introduction of foreign substances. In particular, scratch easily occurs in the prism sheet  32 , and the protective sheet  33  may prevent scratch from occurring in the prism sheet  32 . 
         [0110]    The DBEF  34  that is a kind of polarizing film is also referred to as a reflective polarizing film. 
         [0111]    The DBEF  34  transmits polarized light of the light emitted from the backlight unit  50  in a direction parallel to a polarization direction of the DBEF  34  and reflects polarized light in a different direction from the polarization direction of the DBEF  34 . 
         [0112]    Light is known as a transverse wave that vibrates in a direction perpendicular to a proceeding direction of the light. The polarizing film transmits light that vibrates in a particular direction, of light that vibrates in various directions and absorbs light that vibrates in a different direction from the particular direction of the light, of the light that vibrates in various directions. 
         [0113]    Contrary to this, the DBEF  34  reflects polarized light in a different direction from the polarization direction of the DBEF  34 . Here, the reflected light is recycled in the backlight unit  50 , and brightness of the display apparatus  1  is improved by light recycling. 
         [0114]    Meanwhile, the light scattered in the rear surface  62  of the LGP  60  is emitted toward the quantum dot sheet  37 . In this case, at least a part of the light emitted from the LGP  60  may be absorbed onto the quantum dot sheet  37  and may excite the electrons included in the quantum dots of the quantum dot sheet  37 . The electrons of the quantum dots excited by the light return to its stable state so that light (white light) having various wavelengths can be emitted. 
         [0115]    Also, a part of the light emitted from the LGP  60  is not absorbed onto the quantum dot sheet  37  but may pass through the quantum dot sheet  37 . In this way, the light emitted from the quantum dot sheet  37  includes white light generated by the quantum dot sheet  37  and light that passes through the quantum dot sheet  37 . 
         [0116]    Thus, a part of the light emitted from the quantum dot sheet  37  may pass through the optical member  30  and the display panel  10  and may be output to an outside of the display apparatus  1 . 
         [0117]    In detail, polarized light in the same direction as the polarization direction of the DBEF  34  included in the optical member  30  may pass through the optical member  30  including the DBEF  34  and may be output to the outside of the display apparatus  1  depending on whether the display panel  10  is driven. 
         [0118]    The light output to the outside of the display apparatus  1  may form an image output by the display apparatus  1 . 
         [0119]    Meanwhile, the plurality of light sources  51  of the backlight unit  50  generally output monochromatic light (in particular, blue light) having one wavelength (one color). The light output from the light source  51  is initially monochromatic light, but the monochromatic light is converted into white light in which lights having a plurality of wavelengths (various colors) are mixed with each other, while the light is recycled in the backlight unit  50 . 
         [0120]    As a result, a most part of the light output by the backlight unit  50  becomes white light. 
         [0121]    The white light includes lights having a plurality of wavelengths (various colors) so that color reproducibility of the display apparatus  1  can be improved. 
         [0122]    Meanwhile, a part of the light emitted from the plurality of light sources  51  may be absorbed by the mold frame  40  at edge portions of the display apparatus  1 . That is, the amount of white light generated at the edge portions of the display apparatus  1  may be reduced. Also, a part of monochromatic light (blue light) emitted from the plurality of light sources  51  may pass through the LGP  60 , the quantum dot sheet  37 , the optical member  30 , and the display panel  10  and may be emitted toward the outside of the display apparatus  1 . As a result, a ratio of white light generated by light recycling with respect to the light emitted from the display apparatus  1  is reduced, and a ratio of monochromatic light (blue light) emitted from the plurality of light sources  51  with respect to the light emitted from the display apparatus  1  is increased. Thus, the image output by the display apparatus  1  may appear blue at the edge portions of the display apparatus  1 . 
         [0123]    Also, in this way, when the ratio of white light with respect to the light emitted from the edge portions of the display apparatus  1  is reduced and the ratio of monochromatic light (blue light) with respect to the light emitted from the edge portions of the display apparatus  1  is increased/decreased, there is a difference of color (color coordinates) between the light emitted from the edge portions of the display apparatus  1  and the light emitted from a center portion of the display apparatus  1 . 
         [0124]    In order to prevent this phenomenon, an optical converter  100  may be disposed in the mold frame  40 , as illustrated in  FIG. 3 . 
         [0125]    The mold frame  40  may be formed to have a shape of a rectangular ring. The mold frame  40  may include a first frame  41  disposed to be coupled to the front top chassis  11  and a second frame  42  disposed to be coupled to the rear bottom chassis  12 . In the exemplary embodiment, the first frame  41  and the second frame  42  may be formed integrally with each other or individually. 
         [0126]    The first frame  41  of the mold frame  40  may include a first support surface  41   a  disposed on a front surface of the first frame  41  to support the display panel  10  and a second support surface  41   b  disposed on the front surface of the first frame  41  to support the optical member  30 . 
         [0127]    Meanwhile, the optical converter  100  may be disposed on an inner surface  43  of the mold frame  40  so as to convert the light emitted from the edge portions of the display apparatus  1  into white light. 
         [0128]    The optical converter  100  may be installed in an installation groove  45  recessed into the inner surface  43  of the mold frame  40 . 
         [0129]    The optical converter  100  may include an optical conversion material  110 . 
         [0130]    Here, the optical conversion material  110  that is a material that emits visible rays when light is incident on the optical conversion material  110  from the outside, may include a fluorescent material or quantum dots. 
         [0131]    In other words, when the light is incident on the optical converter  100  of the mold frame  40  from the LGP  60 , a part of the incident light is converted into white light using the optical conversion material  110 , and light reflected by the reflector sheet  35  and white light converted by the optical conversion material  110  may be emitted together. 
         [0132]    In detail, electrons of the optical conversion material  110  are placed at the low energy level (or band) in a stable state, and when the optical conversion material  110  absorbs light from the outside, the electrons at the low energy level move to the high energy level (or band). Because the electrons placed at the high energy level are in an instable state, the electrons naturally move to the low energy level from the high energy level and emit energy in the form of light while moving to the low energy level from the high energy level. Also, the wavelength of the emitted light is determined by an energy difference between the high energy level and the low energy level. 
         [0133]    Thus, when light emitted from the plurality of light sources  51  or the light recycled in the backlight unit  50  is absorbed by the optical conversion material  110 , the optical conversion material  110  may emit light. 
         [0134]    In the exemplary embodiment, when the optical conversion material  110  emits yellow light and red light, yellow light emitted toward the optical conversion material  110  and blue light that passes through the optical conversion material  110  are mixed with each other so that white light can be emitted from the optical conversion material  110 . 
         [0135]    For example, when the blue light is incident from the plurality of light sources  51  toward the optical conversion material  110 , the optical conversion material  110  may generate the yellow light and the red light due to the blue light of the plurality of light sources  51 . In addition, a part of the blue light emitted from the plurality of light sources  51  may pass through the optical conversion material  110 . 
         [0136]    In this way, the yellow light and the red light generated by the optical conversion material  110  and the blue light that passes through the optical conversion material  110  are mixed with one another so that light emitted from the optical conversion material  110  becomes white light having various wavelengths (various colors). 
         [0137]    In this way, the white light generated by the optical conversion material  110  disposed on the inner surface  43  of the mold frame  40  may increase the ratio of white light at edge portions of the backlight unit  50 . In other words, the optical conversion material  110  formed at edge portions of the reflector sheet  35  may compensate for insufficiency of light recycling at the edge portions of the backlight unit  50 . 
         [0138]    As described above, in order to compensate for insufficiency of light recycling at the edge portions of the backlight unit  50 , the optical converter  100  including the optical conversion material  110  is disposed on the inner surface  43  of the mold frame  40  included in the backlight unit  50 . 
         [0139]    In addition, as described above, the optical conversion material  110  disposed in the inner surface  43  of the mold frame  40  has been described. However, the exemplary embodiment is not limited thereto, and the optical conversion material  110  may be coated on the rear surface  62  of the LGP  60  as described below. In other words, the optical conversion material  110  may also be placed between the reflector sheet  35  and the LGP  60 . 
         [0140]    Meanwhile, in the exemplary embodiment of the, the mold frame  40  includes two support surfaces for supporting the display panel  10  and the optical member  30 . However, the exemplary embodiment is not limited thereto. For example, the support surfaces of the mold frame  40  may have various shapes. 
         [0141]    Meanwhile, the optical converter  100  may include optical conversion patterns  120  formed on the LGP  60 . 
         [0142]      FIG. 4  is a schematic view of a light guide plate (LGP) having an optical converter of a display apparatus according to an exemplary embodiment, and  FIG. 5  is an enlarged view of portion B of  FIG. 4 , and  FIG. 6  is a schematic view of an LGP having an optical converter of a display apparatus according to an exemplary embodiment, and  FIG. 7  is a schematic view of an LGP having an optical converter of a display apparatus according to an exemplary embodiment. 
         [0143]    As illustrated in  FIGS. 4 through 7 , the optical converter  100  of the display apparatus  1  includes the optical conversion patterns  120 . 
         [0144]    As illustrated in  FIGS. 4 through 6 , the optical converter  100  may include the optical conversion patterns  120  formed on the rear surface  62  of the LGP  60 . 
         [0145]    In the exemplary embodiment, sizes and shape of the optical conversion patterns  120  may be adjusted in various ways. 
         [0146]    Also, a width of each edge portion of the LGP  60  in which the optical conversion patterns  120  are formed, may be adjusted in various ways. 
         [0147]    Also, the sizes and shape of the optical conversion patterns  120  may be adjusted in various ways. 
         [0148]    In detail, the distance L 1  of each edge portion of the LGP  60  in which the optical conversion patterns  120  are formed, and the sizes and shape of the optical conversion patterns  120  formed to the distance L 1  of each edge portion may be adjusted in consideration of various variable, such as a distance between each light source  51  of the plurality of light sources  51  and the LGP  60 , a width at which the mold frame  40  and the LGP  60  overlap each other, and the thickness of the quantum dot sheet  37 . 
         [0149]    For example, the optical conversion patterns  120  may include oval or racetrack patterns  121  having an oval or a racetrack shape, as illustrated in  FIG. 4 . In the exemplary embodiment, the oval/racetrack patterns  121  may have various sizes in lengths and widths. 
         [0150]    In addition, the oval patterns  121  may adjust a distance X PITCH between respective center of oval/racetrack patterns  121 ′ adjacent in a horizontal direction X and a distance Y PITCH between respective center of oval/racetrack patterns  121 ″ adjacent in a vertical direction Y of the oval patterns  121  as shown in  FIG. 5 . 
         [0151]    For example, if the width, at which the mold frame  40  and the LGP  60  overlap each other, is small, the amount of light blocked by the mold frame  40  is reduced such that the distance L 1  of each edge portion of the LGP  60  in which the optical conversion patterns  120  are formed, can be reduced. On the other hand, if the width, at which the mold frame  40  and the LGP  60  overlap each other, is large, the amount of light blocked by the mold frame  40  is increased such that the distance L 1  of each edge portion of the LGP  60  in which the optical conversion patterns  120  are formed, can be increased. 
         [0152]    Meanwhile, the optical conversion patterns  120  formed in the LGP  60  may include one among diamond-shaped diamond patterns  122  ( FIG. 6 ), circular patterns having a circular shape (not shown), or rectangular patterns (not shown) having a rectangular shape. 
         [0153]    However, the exemplary embodiment is not limited thereto. For example, the optical conversion patterns  120  may include various polygonal shapes, such as a pentagonal shape and a hexagonal shape. 
         [0154]    Also, densities of the optical conversion patterns  120  formed on the LGP  60  may be adjusted in consideration of various variables. 
         [0155]    For example, coating densities of the optical conversion patterns  120  may be reduced according to a distance from the edge portions of the LGP  60 . This is because strongest monochromatic light (blue light) is emitted due to the insufficiency of light recycling at edge portions of the backlight unit  50  and light recycling is increased as the optical conversion patterns  120  get distant from the edge portions of the backlight unit  50  and thus the ratio of white light is increased. 
         [0156]    Also, for example, when the diamond-shaped patterns  122  are formed on the rear surface  62  of the LGP  60 , the optical conversion patterns  120  may be formed at the edge portions of the LGP  60  to have the largest diamond shape, and the area of the diamond-shaped patterns  122  may be reduced as the diamond-shaped patterns  120  get farther away from the edge portions of the LGP  60 . 
         [0157]    In addition, although not shown, the area of the diamond-shaped patterns  122  may be maintained at a constant level, and a distance between the diamond-shaped patterns  122  may vary. For example, the distance between the diamond-shaped patterns  122  placed at the edge portions of the LGP  60  may be the smallest and may also be increased as the diamond-shaped patterns  122  get distant from the edge portions of the LGP  60 . 
         [0158]    Referring to  FIG. 7 , in a display apparatus  1  according to an exemplary embodiment, a film  80  on which optical conversion patterns  120  are formed, may be attached to the LGP  60 . 
         [0159]    The optical conversion patterns  120  having various shapes may be formed in the film  80 . 
         [0160]    The film  80  having the optical conversion patterns  120  formed therein may be attached to the edge portions of the LGP  60 . 
         [0161]    In this case, sizes and densities of the optical conversion patterns  120  formed in the film  80  may be adjusted as described above with respect to  FIG. 5 . 
         [0162]    For example, the film  80  may change the optical conversion patterns  120  patterned based on a distance between the optical conversion patterns  120  and the edge portions of the LGP  60 . For example, the optical conversion patterns  120  placed at the edge portions of the LGP  60  may have the widest area, and the area of the optical conversion patterns  120  may be reduced as the optical conversion patterns  120  get farther away from the edge portions of the LGP  60 . 
         [0163]    Through the above configuration, the display apparatus  1  may reduce a color difference between center and edge portions of the display apparatus  1 . That is, the optical converter  100  including the optical conversion material  110  is formed on the inner surface  43  of the mold frame  40 , and the optical conversion patterns  120 , sizes, densities and shapes of which can be adjusted, are formed in the LGP  60  so that the color difference between the center and the edge portions of the display apparatus  1  can be reduced. 
         [0164]    As described above, in a display apparatus according to the above-described exemplary embodiments, colors of reflected lights emitted from a plurality of light sources disposed at edge portions of a backlight unit are adjusted so that color uniformity can be improved. 
         [0165]    In addition, the occurrence of a color uniformity difference is prevented so that the quality of a product can be improved. 
         [0166]    While exemplary embodiments have been particularly shown and described above, it would be appreciated by those skilled in the art that various changes may be made therein without departing from the principles and spirit of the inventive concept, the scope of which is defined in the following claims.