Abstract:
A backlight unit that allows a slimmer design for a display device is presented. The backlight unit includes: a bottom chassis; a bracket accommodated in the bottom chassis and positioned at an edge of the bottom chassis; a light source unit including a substrate fixedly positioned on the bracket and a light source mounted on the substrate, the light source protruding toward a bottom of the bottom chassis; and a light guide plate disposed in the bottom chassis and transmitting light from the light source.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0016228 filed in the Korean Intellectual Property Office on Feb. 2, 2015, the entire content of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    (a) Relevant Field 
         [0003]    The present disclosure relates to a backlight unit and a liquid crystal display (LCD) including the same. 
         [0004]    (b) Description of the Related Art 
         [0005]    A liquid crystal display (LCD) is one of the most widely used display devices today. Generally, the LCD displays an image by filling a liquid crystal material between an upper substrate formed with common electrodes, color filters, and the like, and a lower substrate formed with thin film transistors, pixel electrodes, and the like, applying different voltages to the pixel and common electrodes to generate an electric field, thereby changing arrangement of liquid crystal molecules, and finally adjusting transmittance of light. An LCD panel of the LCD is in itself a non-emissive type of light receiving element, so the LCD generally includes a backlight unit for supplying light to the LCD panel at a rear side thereof. 
         [0006]    As a light source for the backlight unit, a cold cathode fluorescent lamp (CCFL) has been widely used, since it consumes less power and provides bright white light. 
         [0007]    Recently, a light emitting diode (LED) has been gaining popularity since it has superior color reproducibility, a longer lifespan, and less power consumption. 
         [0008]    The backlight unit may be classified into an edge type and a direct type depending on where a light source is positioned in relation to the LCD panel. In the edge type, a light source is positioned at a lateral side of the LCD panel to provide light through a light guide plate, whereas in the direct type, a light source is positioned at a rear side of the LCD panel to provide light thereto. In terms of space utilization and design aspects, there is a demand for a slimmer display device, making the thickness of a backlight unit a major factor in manufacturing the slimmer display device. 
         [0009]    The edge type is preferable to the direct type for making a slimmer backlight unit. However, in the edge type of backlight unit, the edge closest to the light source is thicker than the other edges, posing a challenge in realizing a slimmer backlight unit. 
         [0010]    The above information disclosed in this Background section is only for enhancement of understanding of the background and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0011]    The inventive concept pertains to a backlight unit and a display device including the same and allowing for a slimmer design. 
         [0012]    In one aspect, the inventive concept pertains to a backlight unit that includes: a bottom chassis; a bracket accommodated in the bottom chassis and positioned at an edge of the bottom chassis; a light source unit including a substrate fixedly positioned on the bracket and a light source mounted on the substrate, the light source protruding toward a bottom of the bottom chassis; and a light guide plate disposed in the bottom chassis and transmitting light from the light source. 
         [0013]    The light source may be positioned between the bracket and the light guide plate. 
         [0014]    The light source may be a light emitting diode (LED) package, and a lateral side of a light emitting surface of the LED package may be mounted on the substrate. 
         [0015]    A heat conducting member may be positioned between and in contact with the bracket and the LED package. 
         [0016]    The bracket may include a groove at a bottom surface, and the bracket may be positioned such that a guide protruding from a bottom of the bottom chassis may be inserted into the groove. 
         [0017]    The substrate may be positioned to contact the bracket, and is fixed to the bracket by a screw. 
         [0018]    The substrate may be attached to the bracket by an adhesion member. 
         [0019]    The backlight unit may further include a thermal insulating member positioned on the substrate. 
         [0020]    The backlight unit may further include a mold frame for holding the display panel in place, and the mold frame may not be positioned at an edge where the light source unit is positioned. 
         [0021]    The bottom chassis may further include a wall extending from edges of the bottom, and a bottom surface of the bracket may contact the bottom and one lateral side thereof may contact the wall. 
         [0022]    A display device according to an exemplary embodiment includes a display panel, and a backlight unit for supplying light to the display panel. The backlight unit includes: a bottom chassis; a bracket accommodated in the bottom chassis and positioned at an edge of the bottom chassis; a light source unit including a substrate fixedly positioned onto the bracket and a light source mounted on the substrate, the light source protruding toward a bottom of the bottom chassis; and a light guide plate disposed in the bottom chassis and transmitting light from the light source. 
         [0023]    The light source may be positioned between the bracket and the light guide plate. 
         [0024]    The light source may be a light emitting diode (LED) package, and a lateral side of a light emitting surface of the LED package may be mounted on the substrate. 
         [0025]    A heat conducting member may be positioned between the bracket and the LED package to contact them. 
         [0026]    The bracket may include a groove at a bottom surface, and the bracket may be positioned such that a guide protruding from a bottom of the bottom chassis may be inserted into the groove. 
         [0027]    The substrate may be positioned to contact the bracket, and may be fixed to the bracket by a screw. 
         [0028]    The substrate may be attached to the bracket by an adhesion member. 
         [0029]    The backlight unit may further include a thermal insulating member positioned on the substrate, and the display panel may be positioned on the thermal insulating member. 
         [0030]    The backlight unit may further include a mold frame for fixing the display panel, and the mold frame may not be positioned on an edge where the light source unit is positioned. 
         [0031]    The bottom chassis may further include a wall extending from edges of the bottom chassis, and a bottom surface of the bracket may contact the bottom and a lateral side of the bracket may contact the wall. 
         [0032]    In the backlight unit according to the exemplary embodiment, since a printed circuit board (PCB) of the light source unit functions as the mold frame at the side where the light source unit is positioned (hereinafter referred to as a light input section), the mold frame may be omitted at the light input section. Accordingly, a thickness of the light input section may be reduced to make the slimmer display device. In addition, since the slimmer display device can be manufactured, there is an advantage in realizing a curved display. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]      FIG. 1  is an exploded perspective view of a liquid crystal display (LCD) including a backlight unit according to an exemplary embodiment. 
           [0034]      FIG. 2  is a perspective view showing a cross-section of the backlight unit illustrated in  FIG. 1  taken from a side where a light input section is positioned. 
           [0035]      FIG. 3  is a perspective view showing a cross-section of the backlight unit illustrated in  FIG. 1  taken from a side where the light source unit is not positioned. 
           [0036]      FIG. 4  is a cross-sectional view of the LCD illustrated in  FIG. 1  taken from the side where the light input section is positioned. 
           [0037]      FIG. 5  is a perspective view of a bracket of the backlight unit according to the exemplary embodiment. 
           [0038]      FIG. 6  is a cross-sectional view of an LCD including a backlight unit according to another exemplary embodiment taken from a side where a light input section is positioned. 
           [0039]      FIG. 7  is a cross-sectional view of an LCD including a backlight unit according to a further exemplary embodiment taken from a side where a light input section is positioned. 
           [0040]      FIGS. 8, 9, 10, and 11  are schematic diagrams for illustrating positions of a light source unit and a mold frame according to some exemplary embodiments. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0041]    The inventive concept will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the inventive concept. 
         [0042]    In the drawings, the thickness of layers, films, panels, regions, etc. are enlarged or exaggerated for clarity. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it may be directly on the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. 
         [0043]    A liquid crystal display (LCD) including a backlight unit according to an exemplary embodiment will now be described in detail with reference to  FIGS. 1 to 5 . 
         [0044]      FIG. 1  is an exploded perspective view of an LCD including a backlight unit according to an exemplary embodiment of the inventive concept,  FIG. 2  is a perspective view showing a cross-section of the backlight unit illustrated in  FIG. 1  taken from a side where a light input section is positioned,  FIG. 3  is a perspective view showing a cross-section of the backlight unit illustrated in  FIG. 1  taken from a side where the light source unit is not positioned, and  FIG. 4  is a cross-sectional view of the LCD illustrated in  FIG. 1  taken from the side where the light input section is positioned.  FIG. 5  is a perspective view of a bracket of the backlight unit according to the exemplary embodiment of the inventive concept. 
         [0045]    Referring to  FIGS. 1 and 2 , the LCD basically includes an LCD panel  100  and a backlight unit  200 . The backlight unit  200  supplies light to the LCD panel, and the LCD panel  100  controls the supplied light to display an image. The LCD further includes a top chassis  300  that protects the LCD panel  100  by enclosing its edges and prevents the LCD panel  100  from being separated from the backlight unit  200 . In some exemplary embodiments, the top chassis  300  may be omitted. 
         [0046]    The LCD panel  100  includes a lower display substrate  110 , an upper display substrate  120 , and a liquid crystal layer (not shown). The lower display substrate  110  and the upper display substrate  120  are attached to each other while maintaining a predetermined interval therebetween, and the liquid crystal layer is formed therebetween. 
         [0047]    The lower display substrate  110  includes a transparent insulation substrate such as glass, and a plurality of thin film transistors, data lines, gate lines, pixel electrodes, etc. that are formed on the insulation substrate. 
         [0048]    A data line is connected to a source terminal of a thin film transistor, and a gate line is connected to a gate terminal. A pixel electrode formed of a transparent conductive material such as indium tin oxide (ITO) is connected to a drain terminal of the thin film transistor. 
         [0049]    The upper display substrate  120  positioned to face the lower display substrate  110  includes a transparent insulation substrate, and color filters, common electrodes, etc. that are formed on the insulation substrate. Each of the color filters may be included to represent primary colors such as red, green, and blue. A common electrode is formed of a transparent conductive material such as indium tin oxide (ITO) and indium zinc oxide (IZO). At least one of the color filter and the common electrode may be positioned in the lower display substrate  110 . 
         [0050]    Polarizers  130  and  140  are attached to a bottom surface of the lower display substrate  110  and to a top surface of the upper display substrate  120 , respectively. The polarizers  130  and  140  may polarize incident light on the LCD panel  100  to allow light vibrating only in one direction to be transmitted. 
         [0051]    In the LCD panel  100 , when the thin film transistor is turned on by a signal applied to the gate line, a signal applied to the data line is applied to the pixel electrode. Then, an electric field of predetermined intensity is generated between the pixel electrode and the common electrode to control alignments of liquid crystal molecules of the liquid crystal layer. Accordingly, transmittance of light passing through the liquid crystal layer is controlled to display an image. 
         [0052]    The liquid crystal display includes at least one driving device (not shown) such as a driver, and a controller that controls signals applied to the LCD panel  100 . As an IC chip, the driving device may be mounted on the LCD panel  100  or on a printed circuit board (PCB) and a flexible printed circuit board (FPCB) to be electrically connected to the LCD panel  100 . Some driving devices may be integrated into the LCD panel  100 . 
         [0053]    The backlight unit  200  is positioned below the LCD panel  100  to supply light to the LCD panel  100 . 
         [0054]    The backlight unit  200  includes a bottom chassis  210  and various components accommodated therein or fixed thereto. The bottom chassis  210  and each of the components will now be described. The bottom chassis  210  is open upward, so it is a kind of container having an accommodating space of a predetermined depth. The bottom chassis  210  may have, for example, an overall quadrangular tray-like shape. The bottom chassis  210  includes a substantially flat bottom  211 , and a wall  212  that upwardly extends from edges of the bottom  211 . Heights of the wall  212  may be the same in the four edges of the bottom chassis  210 , at least one edge may have a different height, or even the same edge may have partially different heights. For example, the height of the wall  212  where a light source unit  230  of the backlight unit  200  to be described later is positioned (i.e., the light input section) may be greater than those of the wall  212  where the light source unit  230  is not positioned. At least one guide  215  is formed in the bottom  211  such that a bracket  220  to be described later is positioned around the edge near the light input section and maintains its original position. The guide  215  upwardly protrudes from the bottom  211 . The guide  215  may protrude in a substantially circular cylindrical shape, but it is not limited thereto, and it may protrude, for example, in a quadrangular pillar shape, or may be elongated to protrude in parallel with the wall. 
         [0055]    The bottom chassis  210  may be formed of a metallic material such as an aluminum plate, an aluminum alloy plate, or zinc-plated steel. In some exemplary embodiments, the bottom chassis  210  may be formed of a plastic material such as polycarbonate (PC). 
         [0056]    In the bottom chassis  210 , the bracket  220 , the light source unit  230 , a reflective sheet  260 , a light guide plate  270 , an optical sheet  280 , etc. are accommodated. Among them, the bracket  220  and the light source unit  230  are placed near the edge of the bottom chassis  210  where the light input section is positioned. 
         [0057]    The bracket  220  is positioned on the bottom  211  of the bottom chassis  210  at the edge thereof where the light input section is positioned such that the light source unit  230  can maintain a predetermined position. The bracket  220  may be positioned close to the wall  212  of the bottom chassis  210  as well as the bottom  211  thereof. 
         [0058]    The bracket  220  is more specifically illustrated in  FIG. 5 .  FIG. 5  (A) is a perspective view seen from above and  FIG. 5  (B) is a perspective view seen from below. As illustrated, the bracket  220  may have an overall thin and long quadrangular bar shape. A groove  221  is formed in a bottom surface of the bracket  220  along a length direction thereof, and at least one hole  225  is formed to penetrate from a top surface to the bottom surface. In some exemplary embodiments, the hole  225  may be formed such that it does not penetrate the bracket  220 . 
         [0059]    The groove  221  is formed to be inserted into the guide  215  of the bottom chassis  210 , allowing the bracket  220  to be fixed at a predetermined position. For this purpose, for example, the groove  221  may be formed such that it has substantially the same width as that of the guide  215  and a greater height than that of the guide  215  protruding from the bottom  211 . In this case, “substantially having the same width” may mean “the width of the groove being slightly greater than that of the guide”. When the widths are exactly the same, inserting one into another may be difficult if either one of the bracket  220  and the guide  215  is not an elastic body. The groove  221  has been exemplarily described such that it is elongated in the bracket  220  to be inserted into the guide  215 , but in some exemplary embodiments, holes, instead of the groove  221 , may be topically formed only at positions where the guides  215  are formed in accordance with a shape of the guide  215 . 
         [0060]    The bracket  220  may be formed of a metallic material having good thermal conductivity such that heat from the light source unit  230  may be transferred to the bottom chassis  210  to prevent the source unit  230  from being overheated. For example, the bracket  220  may be formed through extrusion molding of aluminum, an aluminum alloy, etc. However, a material for the bracket  220  is not limited to the metallic material, and for example, may be formed of a material such as a thermally conductive plastic. 
         [0061]    The light source unit  230  includes a substrate  231  and a light source  232  mounted thereon, and a larger side of the substrate  231  is closely fixed onto the bracket  220 , and the light source  232  downwardly protrudes from the substrate  231  to be positioned between the bracket  220  and the light guide plate  270 . 
         [0062]    The substrate  231  may have an overall elongated bar shape. The substrate  231  serves to support the light source  232  and supply power to the light source  232 . The substrate  231  may be a circuit board, and particularly, a metal core printed circuit board (MCPCB). 
         [0063]    In order to fix the substrate  231  onto the bracket  220 , a hole  235  of the substrate  231  is formed at a position where the hole  225  of the bracket  220  is formed. After the penetration hole  235  of the substrate  231  is aligned to the hole  225  of the bracket  220 , the substrate  231  may be fixed to the bracket  220  by tightening a screw  251  toward the hole  225  from the hole  235 . 
         [0064]    Since the substrate  231  is tightly attached to the bracket  220  and the bracket  220  is tightly attached to the bottom chassis  210 , the heat generated from the light source  232  may be quickly transferred and discharged to the bottom chassis  210  through the substrate  231  and the bracket  220 . That is, the substrate  231 , the bracket  220 , and the bottom chassis  210  may serve as a heat sink of the light source  232 . For effective heat transfer and discharge, the substrate  231  and the bracket  220  may be formed of a material having a superior heat transfer characteristic, and for example, as described above, the substrate  231  may be the MCPCB and the bracket  220  may be formed of the metallic material. 
         [0065]    The light source  232  is electrically connected to wires of the substrate  231  to receive power, and emits light by converting electrical energy into light energy. The light source  232  may be a light emitting diode (LED) package, and a plurality of light sources  232  may be positioned on the single substrate  231  at predetermined intervals. In this case, the LED package is mounted on the substrate  231  such that a light emitting surface faces the light guide plate  270 . 
         [0066]    Since the substrate  231  is fixed onto the bracket  220  and the light source  232  is positioned between the bracket  220  and the light guide plate  270 , a horizontal surface of the substrate  231  and the light emitting surface of the LED package are substantially perpendicular to each other, and a rear side of the light emitting surface of the LED package rather than a lateral side thereof is mounted on the substrate  231 . In addition to the LED package, other possible point or line light sources may be used as the light source  232 . Since a wide surface of the substrate  231  of the light source unit  230  is fixed onto the bracket  220 , an uppermost surface (i.e., top surface of the substrate  231 ) forms a flat surface along the edge of the bottom chassis  210  where the light input section is positioned while the substrate  231  is fixed onto the bracket  220 . Accordingly, even if an additional mold frame on which the LCD panel  100  is placed is not provided to where the light input section is positioned, the substrate  231  serves as the mold frame to position the LCD panel  100  onto the top of the substrate  231 . As a result, the mold frame may be removed from the light input section, thereby reducing a thickness of the light input section. Further, use of the mold frame decreases, so a manufacturing cost may be reduced. 
         [0067]    However, when the LCD panel  100  is placed directly onto the substrate  231 , heat generated from the light source  232  may be transferred to the LCD panel  100  through the substrate  231 . Accordingly, a thin thermal insulating member  240  may be positioned on the substrate  231  to prevent the generated heat from being transferred to the LCD panel  100 . The thermal insulating member  240  may be positioned to cover the entire top surface of the substrate  231  or at least some of the top surface thereof that overlaps LCD panel  100 . The thermal insulating member  240  may be a heat insulating tape, and may be attached to the top surface of the substrate  231 . In order to fix the substrate  231  to the bracket  220  through the screw  251 , a hole  245  of the thermal insulating member  240  may be formed at a position where the hole  235  of the substrate  231  is formed. 
         [0068]    The light guide plate  270  is positioned on the bottom  211  of the bottom chassis  210  such that one edge faces the light source  232 . The light guide plate  270  is used to guide the light emitted from the light source  232  such that the emitted light is transmitted to the LCD panel  100 . The light guide plate  270  may be formed of polymethylmethacrylate (PMMA) having high light transmittance, polycarbonate (PC) having excellent strength and heat resistance, methylmethacrylate-styrene (MS) having excellent heat resistance and humidity resistance, or the like. The light guide plate  270  serves to convert the light generated from the light source unit  230 , which has an optical distribution of a point or line light source, into light having an optical distribution of a surface light source, that is, to uniformly distribute the generated light. A flat or wedge plate may be used as the light guide plate  270 , and one or both surfaces thereof may be formed with a pattern. 
         [0069]    A reflective sheet  260  is positioned below the light guide plate  270 , that is, between the light guide plate  270  and the bottom chassis  210 . The reflective sheet  260  reflects the light traveling toward the light guide plate  270  such that the reflected light is finally directed toward the LCD panel  100 , thereby improving optical efficiency. The reflective sheet  260  may be formed of a plastic material such as polyethylene terephthalate (PET), polycarbonate (PC), and polystyrene (PS). The reflective sheet  260  may include a light reflective material such as titanium dioxide TiO 2  to increase light reflectance. 
         [0070]    The optical sheet  280  is positioned on the light guide plate  270 . The optical sheet  280  may include a diffuser sheet  281 , a prism sheet  282 , a protecting sheet  283 , etc. The diffuser sheet  281  is used to allow the light emitted from the light guide plate  270  to have uniform distribution, that is, to generate a surface light source of uniform brightness. The prism sheet  282  controls a traveling direction of the light diffused by the diffuser sheet  281  such that the traveling direction of the light is perpendicular to the LCD panel  100 . The protecting sheet  283  may be used to protect a prism of the prism sheet  282  from scratches and the like. The protecting sheet  283  may also serve to widen a viewing angle that is previously narrowed by the prism sheet  282 . 
         [0071]    The optical sheet  280  may exclude one of the prism sheet  282  and the protecting sheet  283  while including a plurality of the others. The optical sheet  280  may further include an optical sheet having characteristics other than those described above. For example, the optical sheet  280  may include a reflective polarizer sheet that can improve luminance efficiency by separating, transmitting, and reflecting polarization components of light. 
         [0072]    The backlight unit  200  includes a mold frame  290  that has a predetermined height to stably fix the LCD panel  100  to the backlight unit  200 . As described above, since the substrate  231  of the light source unit  230  may serve as the mold frame in the light input section where the light source unit  230  is positioned, the mold frame  290  is not positioned in the light input section. 
         [0073]    The mold frame  290  may be combined with the bottom chassis  210 , for example, such that it is hooked and fastened to a hook (not shown) and the like that enclose the wall  212  of the bottom chassis  210 . In this case, a part of the mold frame  290  may press the optical sheet  280  to limit movement of the optical sheet  280  as well as the light guide plate  270  and the reflective sheet  260  therebelow. The mold frame  290  may be formed in one piece or a plurality of pieces. 
         [0074]    The LCD panel  100  is fixed onto the mold frame  290 . The LCD panel  100  may be attached to a flat surface of the mold frame  290  through an adhesion member (not shown), and the adhesion member may be a double-sided cushion tape having impact-absorbing capability to reduce impacts applied to the LCD panel  100 . In the light input section, the LCD panel  100  may be fixed onto the thermal insulating member  240  that is positioned on the substrate  231  of the light source unit  230 , or may not be fixed thereon but placed thereon. 
         [0075]    Though not illustrated, an inverter board and/or a PCB for signal conversion may be mounted on a bottom surface of the bottom chassis  210  as a PCB for power supply. The inverter board converts an external power supply into a constant voltage level to supply it to the light source  232 . The PCB for signal conversion may convert an analog data signal into a digital data signal to transmit it to the LCD panel  100  through the flexible printed circuit board attached to the LCD panel  100 . 
         [0076]    A process of supplying light of a backlight unit  200  having the aforementioned structure to an LCD panel  100  will now be briefly described. First, when power is supplied to a light source  232  through a substrate  231  fixed onto a bracket  220 , the light source  232  generates and emits light. The emitted light is uniformly distributed while passing through a light guide plate  270  to be directed toward an optical sheet  280 , and light emitted from a bottom  211  of a bottom chassis  210  is reflected by a reflective sheet  260  to be directed to the optical sheet  280 . Subsequently, the light is diffused while passing through the optical sheet  280 , and is controlled in its travelling direction such that it is supplied over an entire surface of the LCD panel  100 . 
         [0077]    Meanwhile, the light source  232  generates heat when generating the light. The generated heat is transferred to the bottom chassis  210  through the substrate  231  and the bracket  220  contacting each other in a wide area to be discharged to the outside. Since the heat is blocked by a thermal insulating member  240  positioned therebetween in a direction toward the LCD panel  100  positioned on the substrate  231 , the heat may be prevented from being transferred to the LCD panel  100  from the substrate  231 . 
         [0078]    An LCD including a backlight unit according to another exemplary embodiment will now be described with reference to  FIGS. 6 and 7 . 
         [0079]      FIG. 6  is a cross-sectional view of an LCD including a backlight unit according to another exemplary embodiment taken from a side where a light input section is positioned. 
         [0080]    The exemplary embodiment of  FIG. 6  is substantially the same as the aforementioned exemplary embodiment illustrated in  FIGS. 1 to 5 , but it is different in that a heat conducting member  253  is positioned between the bracket  220  and the light source  232 . The substrate  231  of the light source unit  230  is fixed onto the top surface of the bracket  220 , but the light source  232  is mounted only on the substrate  231  and there may be an interval between the light source  232  and the bracket  220 . In the current exemplary embodiment, the heat conducting member  253  having a thickness corresponding to the interval is positioned between the bracket  220  and the light source  232  to allow the light source  232  to contact the bracket  220  through the heat conducting member  253 . In this case, heat generated from the light source  232  may be partially transferred to the bracket  220  through the heat conducting member  253  without passing through the substrate  231 , thereby improving heat dissipation efficiency. One side of the heat conducting member  253  may be attached to a lateral side of the bracket  220  or the light source  232 , or both sides of the heat conducting member  253  may be respectively attached to lateral sides of the bracket  220  and the light source  232 . 
         [0081]      FIG. 7  is a cross-sectional view of an LCD including a backlight unit according to a further exemplary embodiment taken from a side where a light input section is positioned. 
         [0082]    The exemplary embodiment of  FIG. 7  is substantially the same as the aforementioned exemplary embodiment illustrated in  FIGS. 1 to 5 , but it is different therefrom in that a thin adhesion member  252  is positioned between the bracket  220  and the substrate  231 . The substrate  231  and the bracket  220  are adhered by the adhesion member  252  such that the light source unit  230  is fixed to its original position. Accordingly, as in the aforementioned exemplary embodiment, there is no need to respectively form the holes  225  and  235  in the bracket  220  and the substrate  231 , so there is no need to tighten the screw  251  into the holes  225  and  235 . The adhesion member  252  may cause an overall thickness to increase by a thickness of the adhesion member  252 , but there is no need to tighten the screw to fix the substrate  231  onto the bracket  220 , as shown in the aforementioned exemplary embodiment, thereby reducing an assembly time. In addition, a manufacturing cost of parts can be reduced because a perforation process is eliminated. 
         [0083]    Positions of a light source unit  230  and a mold frame  290  will now be described with reference to  FIGS. 9 to 11 . 
         [0084]      FIGS. 8, 9, 10, and 11  are schematic diagrams for illustrating positions of a light source unit and a mold frame according to some exemplary embodiments. 
         [0085]      FIGS. 8 to 10  are schematic top plan views of the light source unit  230  and the mold frame  290  to show a positional relationship between the light source unit  230  and the mold frame  290 . The backlight unit  200  may have a rectangular shape that is identical to that of a generic LCD panel. The backlight unit  200  has four edges, and two edges (long sides) thereof are relatively longer while the other two edges (short sides) are relatively shorter. 
         [0086]    Referring first to  FIG. 8 , the light source unit  230  is positioned at one short side, while the mold frame  290  is positioned at the other short side and the two long sides. In the short side where the light source unit  230  is positioned (i.e., the light input section), the substrate  231  of the light source unit  230  provides a flat and wide surface on which one edge of the LCD panel may be placed, so the mold frame  290  is not positioned in the light input section. The mold frame  290  may be mounted on the other three edges to provide the flat surface on which the other three edges are positioned. The mold frame  290  may be formed in one piece or two or more pieces so as to be mounted. 
         [0087]    In an exemplary embodiment of  FIG. 9 , the light source unit  230  is positioned on two short sides. The mold frame  290  is not positioned at the short sides where the light source unit  230  is positioned, but is positioned only at two long sides. The mold frame  290  positioned at each of the long sides may be formed in one piece or in a plurality of pieces. 
         [0088]    The exemplary embodiment of  FIG. 10  and the exemplary embodiment of  FIG. 11  are respectively similar to those of  FIG. 8  and  FIG. 9 , but they are different in that the light source unit  230  is positioned at one long side. The mold frame  290  is not positioned at the long side where the light source unit  230  is positioned, but is positioned on the other long side and two short sides ( FIG. 10 ) or only on two short sides ( FIG. 11 ). 
         [0089]    While this inventive concept has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the concept is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.