Abstract:
Provided is a backlight assembly and a liquid crystal display including: a light source; a light guide plate; and a bottom chassis comprising an accommodating portion, a light source cover configured to accommodate the light source, a first sidewall, and a second sidewall, the accommodating portion comprising a first accommodating portion and a second accommodating portion detachably coupled with each other, wherein the light source cover is formed on a first edge of the first accommodating portion, the first sidewall is formed on a second edge of the first accommodating portion, and the second sidewall is formed on an edge of the second accommodating portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/870,691, filed on Oct. 11, 2007 and claims priority from and the benefit of Korean Patent Application No. 10-2006-0099498, filed on Oct. 12, 2006, both of which are hereby incorporated by reference for all purposes as if fully set forth herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1 Field 
         [0003]    The present disclosure relates to a backlight assembly and a liquid crystal display device including the same. More particularly, the present disclosure relates to a backlight assembly and a liquid crystal display device including the backlight assembly, where the liquid crystal display device is slim, lightweight, and requires low manufacturing costs because the device integrates a bottom chassis and a lamp cover. 
         [0004]    2. Discussion of the Background 
         [0005]    Liquid crystal display (“LCD”) devices have increasingly been used in a broad range of applications because LCDs are lightweight, compact, and require low power consumption. An LCD device includes an LCD module and a driving circuit for driving the LCD module. 
         [0006]    The LCD module includes an LCD panel including liquid crystal cells arranged in a matrix format between two transparent substrates, and a backlight assembly which emits light to the LCD panel. 
         [0007]    The backlight assembly includes a lamp for emitting light to the LCD panel, a lamp housing for covering the lamp, a light guide plate for guiding incident light from the lamp toward the LCD panel, a reflection sheet located on the inner surface of the light guide plate, and a plurality of optical sheets stacked on the light guide plate. 
         [0008]    Although there are various types of backlight assemblies, a backlight assembly including a lamp cover for seating the lamp is commonly used. However, stacking the lamp cover on the backlight assembly increases the thickness of the LCD device. This structure increases the LCD device&#39;s manufacturing costs because the LCD device includes the lamp cover for preventing light emitted from the lamp from proceeding thereunder and a reflection material coated on the lamp cover for guiding the light toward the light guide plate. 
       SUMMARY OF THE INVENTION 
       [0009]    The present disclosure provides a backlight assembly and an LCD device including the backlight assembly, where the liquid crystal display device is slim, lightweight, and requires low manufacturing costs because the device integrates a bottom chassis and a lamp cover. 
         [0010]    Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. 
         [0011]    The present application discloses a backlight assembly, comprising: a light source; a light guide plate; and a bottom chassis comprising an accommodating portion, a light source cover configured to accommodate the light source, and first and second sidewalls, the accommodating portion comprising a first accommodating portion and a second accommodating portion configured to separatably engage with each other, wherein the light source cover is formed on a first edge of the first accommodating portion, the first sidewall is formed on a second edge of the first accommodating portion, and the second sidewall is formed on an edge of the second accommodating portion. 
         [0012]    The present application also discloses a liquid crystal display device, comprising: a liquid crystal display panel; a driving circuit to drive the liquid crystal display panel; a light source to provide the liquid crystal display panel with light; a light guide plate to guide the light emitted from the light source toward the liquid crystal display panel; and a bottom chassis comprising an accommodating portion, a light source cover configured to accommodate the light source, and first and second sidewalls, the accommodating portion comprising a first accommodating portion and a second accommodating portion configured to separatably engage with each other; and a top chassis enclosing edge portions of the liquid crystal display panel and covering side surfaces of the bottom chassis, wherein the light source cover is formed on a first edge of the first accommodating portion, the first sidewall is formed on a second edge of the first accommodating portion, and the second sidewall is formed on an edge of the second accommodating portion. 
         [0013]    The present application discloses a backlight assembly, comprising: a lamp; a light guide plate configured to guide light emitted from the lamp; an optical sheet disposed on the light guide plate; and a chassis configured to accommodate the lamp, the light guide plate, and the optical sheet, the chassis comprising a first chassis and a second chassis, wherein the first chassis and the second chassis are configured to be separatably coupled together such that an upper surface of the first chassis is coplanar with an upper surface of the second chassis, the coplanar upper surfaces forming an accommodating portion, and wherein the light source cover is formed on a first edge of the first chassis, the first sidewall is formed on a second edge of the first chassis, and the second sidewall is formed on an edge of the second chassis. 
         [0014]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are included to provide a further understanding of the invention are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention. 
           [0016]      FIG. 1  is an exploded perspective view showing an LCD according to an exemplary embodiment of the present invention. 
           [0017]      FIG. 2  is a cross-sectional view taken along line I-I′ of  FIG. 1 . 
           [0018]      FIG. 3  is a graphical view showing a first bottom chassis engaged with a second bottom chassis of  FIG. 1 . 
           [0019]      FIG. 4A ,  FIG. 4B ,  FIG. 5A ,  FIG. 5B ,  FIG. 5C ,  FIG. 5D ,  FIG. 6A  and  FIG. 6B  are graphical views showing the first bottom chassis and the second bottom chassis of  FIG. 3  according to exemplary embodiments of the present invention. 
           [0020]      FIG. 7  is a graphical view showing a method of engaging the first bottom chassis and the second bottom chassis shown in  FIG. 4A  and  FIG. 4B . 
           [0021]      FIG. 8  is a perspective view showing a backlight assembly shown in  FIG. 1 . 
           [0022]      FIG. 9  is a cross-sectional view of the LCD device including a lamp cover and a mold frame according to an exemplary embodiment of the present invention. 
           [0023]      FIG. 10  is a perspective view showing an LCD device according to an exemplary embodiment of the present invention. 
           [0024]      FIG. 11  is a graphical view showing a reflection sheet according to an exemplary embodiment of the present invention. 
           [0025]      FIG. 12  is a cross-sectional view taken along line II-II′ of  FIG. 10 . 
           [0026]      FIG. 13  is a graphical view showing a bottom chassis according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Various exemplary embodiments of the invention are described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative size of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. 
         [0028]    It will be understood that when an element such as a layer, film, region or substrate is referred to as being “on”, “connected to”, or “coupled to” another element or layer, it can be directly on, directly connected to, or directly coupled to the other element or layer, or intervening elements or layers may also be present. In contrast, when an element is referred to as being “directly on”, “directly connected to”, or “directly coupled to” another element or layer, there are no intervening elements or layers present. 
         [0029]      FIG. 1  is an exploded perspective view showing an LCD device according to an exemplary embodiment of the present invention, and  FIG. 2  is a cross-sectional view taken along line I-I′ of  FIG. 1 . 
         [0030]    The LCD device shown in  FIG. 1  and  FIG. 2  includes an LCD panel  120 , a backlight assembly  170 , a mold frame  110 , a top chassis  100 , and a bottom chassis  90  divided into a first bottom chassis  92  and a second bottom chassis  94 . 
         [0031]    The LCD panel  120  includes a thin film transistor (“TFT”) substrate  124 , and a color filter substrate  122  facing the TFT substrate  124 . Liquid crystals (not shown) are disposed between the TFT substrate  124  and the color filter substrate  122 . The LCD panel  120  displays an image by controlling the light transmissivity of the liquid crystals using TFTs switching element that are arranged in a matrix format. The color filter substrate  122  includes RGB color filters thereon for generating a desired color. Therefore, light transmitted through the liquid crystals is expressed as a desired color through the RGB color filters for displaying an image. 
         [0032]    The top chassis  100  covers an upper edge portion of the LCD panel  120 , and side surfaces of the top chassis  100  are formed to cover side surfaces of the mold frame  110  and the bottom chassis  90 . 
         [0033]    The mold frame  110  accommodates the LCD panel  120  and the backlight assembly  170  to prevent movement thereof and to absorb an outside impact on the LCD panel  120  and the backlight assembly  170 . The mold frame  110  may be formed of synthetic resins or plastics to be insulated from a driving circuit. 
         [0034]    The backlight assembly  170  includes a lamp  182 , a reflection sheet  190 , a light guide plate  160 , a diffusion sheet  176 , a prism sheet  174 , and a protection sheet  172  and supplies light to the LCD panel  120 . 
         [0035]    The lamp  182  may be comprised of at least one cold cathode fluorescence lamp having a bar shape for generating light, a lamp electrode line  183  connected to both ends of the lamp  182  for applying a driving voltage. Alternatively, the at least one cold cathode fluorescent lamp may be replace with a plurality of light emitting diodes for generating light. The lamp  182  may be fixed by a lamp holder  184 . 
         [0036]    The sheets include the diffusion sheet  176 , the prism sheet  174 , and the protection sheet  172 . The diffusion sheet  176  and the prism sheet  174  are combined with two or three sheets, and diffuse and converge light emitted from the light guide plate  182 , improving brightness and a viewing angle of the LCD device. The protection sheet  172  may be stacked on the diffusion sheet  176  or the prism sheet  174  for protecting sheets sensitive to dust or scratching and for preventing movement of the sheets and the backlight assembly  170 . 
         [0037]    The light guide plate  160  uniformly distributes light emitted from the lamp  182  across the entire surface of the light guide plate  160 , and then guides the light toward the LCD panel  120 . For doing so, the light guide plate  160  may be formed of a transparent, thermal resistant polycarbonate, or a transparent acryl resin with a high refraction index. The light guide plate  160  has a protrusion portion  162  formed on at least one side surface thereof as shown in  FIG. 8 . The protrusion portion  162  of the light guide plate  160  is fixed to a groove  164  of an inner sidewall  314  of the bottom chassis  90 . 
         [0038]    Referring back to  FIG. 1 , the reflection sheet  190  reflects light emitted from a lower portion of the light guide plate  160  back toward the light guide plate  160 . For doing so, the reflection sheet  190  may have a basic material coated with a highly reflective material. The basic material may include aluminum (Al), polyethylene terephthalate (PET), etc. and the reflective material may include silver (Ag), titanium (Ti), etc. The bottom chassis  90  is divided into the first bottom chassis  92  and the second bottom chassis  94 . 
         [0039]      FIG. 3  shows a graphical view of the first bottom chassis  92  engaged with the second bottom chassis  94  of  FIG. 1 . The first bottom chassis  92  includes a first accommodating portion  192 , a first inner sidewall  312 , a first lamp cover  302 , and first and second opening portions  402  and  404 . The second bottom chassis  94  includes a second accommodating portion  194 , a second inner sidewall  314 , a second lamp cover  304 , and third and fourth opening portions  406  and  408 . 
         [0040]    The first bottom chassis  92  and the second bottom chassis  94  are engaged to face each other. The first accommodating portion  192  of the first bottom chassis  92  and the second accommodating portion  194  of the second bottom chassis  94  provide an accommodating space, which accommodates the light guide plate  160 , the optical sheets  172 ,  174  and  176 , and the reflection sheet  190 . The first accommodating portion  192  and the second accommodating portion  194  are formed to be symmetrical to each other, and their facing surfaces may be formed in an ‘L’ shape and a reverse ‘L’ shape. 
         [0041]      FIG. 4A  and  FIG. 4B  show graphical views of exemplary embodiments of the first bottom chassis  92  and the second bottom chassis  94  of  FIG. 3 , respectively. 
         [0042]    Referring to  FIG. 4A  and  FIG. 4B , the first bottom chassis  92  includes a first mounting portion  202  formed to overlap and engage an area of the second accommodating portion  194 , a first mounting hole  502 , and a first accommodating hole  512 . The second bottom chassis  94  includes a second mounting portion  204  formed to overlap and engage an area of the first accommodating portion  192 , a second accommodating hole  504 , and a second mounting hole  514 . The first accommodating portion  192  forms the first mounting portion  202  such that a stepped portion is formed at an area in contact with the second accommodating portion  194 . 
         [0043]    The first mounting portion  202  is formed from the first accommodating portion  192  in a single body and second mounting portion  204  is formed from the second accommodating portion  194  in a single body. 
         [0044]    When the first bottom chassis  92  engages the second bottom chassis  94 , the first mounting portion  202  engages and overlaps the second accommodating portion  194  at an area equivalent to the width of the first mounting portion  202 , and the second mounting portion  204  engages and overlaps the first accommodating portion  192  at an area equivalent to the width of the second mounting portion  204 . In this manner, the engagement of the first bottom chassis  92  and the second bottom chassis  94  may prevent light emitted from the lamp  182  from leaking through a gap between the facing surfaces of the first accommodating portion  192  and the second accommodating portion  194 . Further, the intersection and overlapping of the first accommodating portion  192  and the second accommodating portion  194  strengthens the engagement between the first bottom chassis  92  and the second bottom chassis  94 . 
         [0045]      FIG. 5A ,  FIG. 5B ,  FIG. 5C  and  FIG. 5D  show graphical views of exemplary embodiments of the first bottom chassis  92  and the second bottom chassis  94  of  FIG. 3 , respectively. 
         [0046]    As shown in  FIG. 5A  and  FIG. 5B , a second mounting portion  204   a  of the second bottom chassis  94  is formed such that a stepped portion is formed across the entire width of the second bottom chassis  94  and in contact with the first accommodating portion  192  across the entire width of the first bottom chassis  92 . The first accommodating portion  192  is also formed to overlap and engage the second accommodating portion  194  across the entire width of the second bottom chassis  94 . Alternatively, as shown in  FIG. 5C  and  FIG. 5D , the first accommodating portion  192  may form a first mounting portion  202   a  to overlap and engage the second accommodating portion  194  across the entire width of the second bottom chassis  94 . 
         [0047]    The first mounting portion  204   a  is formed from the first accommodating portion  192  in a single body, and the second mounting portion  202   a  is formed from the second accommodating portion  194  in a single body. 
         [0048]      FIG. 6A  and  FIG. 6B  show graphical views of exemplary embodiments of the first bottom chassis  92  and the second bottom chassis  94  of  FIG. 3 , respectively. 
         [0049]    As shown in  FIG. 6A  and  FIG. 6B , the first mounting portion  212  is arranged under the first accommodating portion  192  to form a stepped portion and overlaps and engages an area in contact with the second accommodating portion  194 . In other words, the second accommodating portion  194  is mounted on the first mounting portion  212  which partially extends from the first accommodating portion  192  and forms a stepped portion by a constant distance. Likewise, the second mounting portion  214  partially extends from the second accommodating portion  194  and forms a stepped portion by a constant distance. The first mounting portion  212  is formed from the first accommodating portion  192  in a single body, and the second mounting portion  214  is formed from the second accommodating portion  194  in a single body. 
         [0050]    Alternatively, the first accommodating portion  192  includes a first inner sidewall  322  perpendicular to the first accommodating portion  192 , and the second accommodating portion  194  includes a second inner sidewall  324  perpendicular to the second accommodating portion  194 . The first inner sidewall  322  includes sidewalls  322   a  and  322   b  formed at both sides of the first accommodating portion  192 , and the second inner sidewall  324  includes sidewalls  324   a  and  324   b  formed at the both sides of the second accommodating portion  194 . 
         [0051]    As shown in  FIG. 7 , the overlap and engagement of the first accommodating portion  192  to the second accommodating portion  194  may be strengthened by using screws  506  and  507 . A screwing method will be described with reference to  FIG. 4A  and  FIG. 4B  as previously described above. The first mounting hole  502  formed in the first mounting portion  202  and the second accommodating hole  504  formed at a position corresponding to the first mounting hole  502  are aligned and secured by the first screw  506 . The second mounting hole  514  formed in the second mounting portion  204  and the first accommodating hole  512  formed at a position corresponding to the second mounting hole  514  are aligned and secured by the second screw  507 . Alternatively, a plurality of screws may be used at desired positions for improving a securing strength. In this way, the overlap and engagement of the first accommodating portion  192  and the second accommodating portion  194  may prevent light from leaking toward the lower portion of the light guide plate  160 . Further, the light guide plate  160 , the optical sheets  172 ,  174 , and  176 , and the reflection sheets  186  and  188  may be more easily accommodated by dividing the bottom chassis  90  into the first bottom chassis  92  and the second bottom chassis  94 . 
         [0052]    As shown in  FIG. 8 , the first inner sidewall  312  accommodates the light guide plate  160 , the optical sheets  172 ,  174 , and  176 , and the reflection sheets  186  and  188 . The light guide plate  160  is fixed by the first inner sidewall  312 . The groove  164  is formed at a position corresponding to the protrusion portion  162  of the light guide plate  160  in the first inner sidewall  312  perpendicular to the first accommodating portion  192  (refer to  FIG. 3 ,  FIG. 4A  and  FIG. 4B ). Accordingly, by combining the groove  164  of the first inner sidewall  312  with the protrusion  162  of the light guide plate  160 , the securing strength of the light guide plate  160  and the bottom chassis  90  may be improved. Alternatively, the protrusion portion  162  may be formed on the second inner sidewall  314 , and the groove  164  may be formed on the light guide plate  160  at a position corresponding to the protrusion portion  162  Like the first inner sidewall  312 , the second inner sidewall  314  may have a groove  164  or a hole into which the protrusion portion  162  of the light guide plate  160  is inserted. 
         [0053]    The first lamp cover  302  and the second lamp cover  304  extend from one side surfaces of the first bottom chassis  92  and the second bottom chassis  94 , respectively, and are bent to enclose a lamp reflection layer  185  and the lamp  182  fixed by the lamp holder  184 . The first lamp cover  302  and the second lamp cover  304  are formed in a ‘C’ shape, for example, to accommodate the lamp  182  and the lamp reflection layer  185 . Accordingly, the first lamp cover  302  and the second lamp cover  304  accommodate the lamp  182 . The lamp electrode line  183  for applying a driving voltage to the lamp  182  is exposed to an external circuit and is disposed between the first and second lamp covers  302  and  304  and the mold frame  110 . More specifically, as shown in  FIG. 2 , the lamp electrode line  183  disposed between the first lamp cover  302  and the mold frame  110  is supported and secured by bending side surface of the first lamp cover  302 . Further, as shown in  FIG. 9 , when the side surface of the first lamp cover  302  is flat, a protrusion portion  110   a  of the mold frame  110  is formed between the first lamp cover  302  and the mold frame  110  to support and fix the lamp electrode line  183 . Meanwhile, the first lamp cover  302  may be formed of a material with high reflectivity for reflecting light generated from the lamp  182  toward the light guide plate  160 , thereby improving light efficiency of the LCD device. 
         [0054]    The lamp reflection layer  185  may be formed of a material with high reflectivity on an inner surface of the first lamp cover  302 . The lamp reflection layer  185  reflects light emitted from the lamp  182  toward an incident surface of the light guide plate  160 , thus improving light efficiency. The lamp reflection layer  185  is attached to the inner surface of the first lamp cover  302  by an adhesive. Alternatively, the lamp reflection layer  185  may be coated with a reflective material such as Ag or Al to enclose the inner surface of the first lamp cover  302 . The second lamp cover  304  has the same structures as the first lamp cover  302 . Therefore, repetitive descriptions will be omitted. 
         [0055]    As shown in  FIG. 3  and  FIG. 8 , the first to fourth opening portions  402 ,  404 ,  406  and  408  allow the lamp electrode line  183  connected to the lamp  182  to be exposed to an external circuit. The first opening portion  402  is exposed by a constant distance at an area in contact with the first lamp cover  302  and the first inner sidewall  312 ; the second opening portion  404  is exposed by a constant distance at an area in contact with the first lamp cover  302  and the second inner sidewall  314 ; the third opening portion  406  is exposed by a constant distance at an area in contact with the second lamp cover  304  and the second inner sidewall  314 ; and the fourth opening portion  408  is exposed by a constant distance at an area in contact with the second lamp cover  304  and the first inner sidewall  312 . The lamp electrode lines  183  connected to the lamp  182  inserted into the first lamp cover  302  are exposed through the first opening portion  402  and the second opening portion  404 . The lamp electrode lines connected to the lamp  182  inserted into the second lamp cover  304  are exposed at the third opening portion  406  and the fourth opening portion  408 . Accordingly, the lamp electrode lines  183  may be easily moved and connected to an external circuit. 
         [0056]      FIG. 10  and  FIG. 12  show a perspective view and a cross-sectional view, respectively, of the LCD device according to another exemplary embodiment of the present invention. 
         [0057]      FIG. 10  and  FIG. 12  are the same configurations as those of  FIG. 1  and  FIG. 2 , except for the addition of a reflection sheet. Accordingly, any repetitive descriptions will be omitted. 
         [0058]    The reflection sheet includes first and second reflection sheets  186  and  188  where the reflection sheet reflects light emitted to the lower portion of the light guide plate  160  back toward the light guide plate  160 . For doing so, the first and second reflection sheets  186  and  188  may have a basic material coated with a material with high reflectivity. The basic material may be Al, PET, etc. and the reflective material may be Ag, Ti, etc. 
         [0059]    The first reflection sheet  186  is bent into a shape similar to the second lamp cover  304  and the second reflection sheet  188  is bent into a shape similar to the first lamp cover  302 . The first reflection sheet  186  and the second reflection sheet  188  are stacked on the first lamp cover  302  and the second lamp cover  304  and reflect light generated from the lamp  182  back toward the light guide plate  160 , thus improving light efficiency. Meanwhile, as shown in  FIG. 11 , a single reflection sheet  187  may be formed to have both ends  84  and  86  bent into a shape similar to the first lamp cover  302  and the second lamp cover  304  and to enclose the lamp  182 . 
         [0060]      FIG. 13  shows a perspective view of a bottom chassis according to an exemplary embodiment of the present invention. 
         [0061]    As shown in  FIG. 13 , the bottom chassis comprises an accommodating portion  292 , an inner sidewall  332 , first and second lamp covers  322  and  324 , and a light guide plate inserting portion  334 . The accommodating portion  292  and the inner sidewall  332  provide an accommodating space which may accommodate the light guide plate  160 , the optical sheets  172 ,  174 , and  176 , and the reflection sheet  190 . The first and second lamp covers  322  and  324  extend from both sides of the bottom chassis and are bent in a shape to enclose the lamp  182  fixed by the lamp holder  184  and the lamp reflection layer  185 . The first and second lamp covers  322  and  324  are formed in a ‘C’ shape to accommodate the lamp  182  and the lamp reflection layer  185  in a ‘C’ shape. The light guide plate inserting portion  334  is formed to provide an open area facing the inner sidewall  332 . Because the area corresponding to the sidewall  332  of the bottom chassis is open, the light guide plate  160 , the optical sheets  172 ,  174 , and  176 , and the reflection sheet  190  may be easily accommodated. 
         [0062]    As described above, the backlight assembly and the LCD device including the backlight assembly according to the present invention enclose the lamp by bending both sides of the bottom chassis and dividing the bottom chassis into the first and second bottom chassis. Accordingly, since an additional lamp cover is unnecessary, the present invention may reduce manufacturing costs and provide a slim, lightweight LCD device. 
         [0063]    Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts taught herein, which may appear to those skilled in the present art, will still fall within the spirit and scope of the present invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.