Patent Publication Number: US-2005122048-A1

Title: Surface light source device and liquid crystal display device having the same

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a surface light source device and liquid crystal display device having the same. More particularly, the present invention relates to a surface light source device in which an external electrode is disposed on an outer surface of a light source body and a power transfer unit that connects the external electrode to an inverter to provide a discharge voltage to the external electrode, and a liquid crystal display device having the same.  
      2. Description of the Related Art  
      Information-processing devices display processed information via display devices such as liquid crystal display (LCD) apparatuses. LCD apparatuses display images using liquid crystals. The apparatuses have been widely used in various fields, because LCD apparatuses have many advantages such as thinner, lighter, low power consumption, low driving voltage, etc.  
      LCD apparatuses include a liquid crystal display panel for displaying images and a backlight assembly for providing light to the LCD panel. Backlight assemblies are classified as either an edge type backlight assembly or a direct lumination type backlight assembly. An edge type backlight assembly includes a light source disposed on a side surface of a light guide plate. The light generated from the light source is radially reflected through one surface of the light guide plate, and provided to a LCD panel. A direct lumination type backlight assembly includes a plurality of light sources disposed under a LCD panel, a diffusion plate disposed over the light source, and a reflection plate disposed under the light source. The direct lumination type backlight assembly has high brightness but does not have uniform brightness, while the edge type backlight assembly has low brightness and uniform brightness.  
      Backlight assemblies further include a light guide plate, a diffusion member and an optical member such as a prism sheet to improve brightness and uniformity of the brightness when a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) is used as a light source. Therefore, LCD apparatuses in which CCFLs or LEDs are used as light sources have increased volume and weight, resulting in increased manufacturing costs. Recently, surface light source devices have been developed in which discharging is used to provide a light source.  
      Surface light source devices include internal or external electrodes to generate a light source in response to a discharge voltage. The discharge voltage is applied to the electrodes through a plurality of wires withdrawn from an external power supply unit. The wires are connected to the electrodes via a soldering process.  
      Although a soldering process may improve an electric characteristic between the wires and the electrodes, the connection may be easily broken due to an external impact. Further, the electrodes may be damaged by heat generated during the soldering process. Furthermore, the wires are tied to one pair in order to be directly connected to the electrodes, resulting in a complicated process for manufacturing the surface light source.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention provides a surface light source device having electrically improved properties.  
      The present invention also provides a liquid crystal display device having the above surface light source device.  
      According to one aspect of the present invention, a surface light source device, comprises a light source body including a discharge space to generate a light source; at least one external electrode, which is disposed on an outer surface of one end of the light source body, is extended in a first direction, and applies a discharge voltage to the discharge space; and at least one power transfer unit, combined with the at least one external electrode, to apply the discharge voltage to the at least one external electrode.  
      According to another aspect of the present invention, a liquid crystal display device, comprises a surface light source, including: a light source body including a discharge space to generate a light source; and at least one external electrode, which is disposed on an outer surface of one end of the light source body, is extended in a first direction, and applies a discharge voltage to the discharge space; at least one power transfer unit, combined with the at least one external electrode, to apply the discharge voltage to the at least one external electrode; a receiving container to receive the surface light source; and a liquid crystal display unit, disposed on an upper of the surface light source, to display an image with the light source generated from the surface light source.  
      According to the present invention, the surface light source device and the liquid crystal display device have improved electric properties thereof because a discharge voltage is applied to the first and second external electrodes through at least one power transfer unit.  
      This application relies for priority upon Korean Patent Application No. 2003-87920 filed on Dec. 5, 2003, the contents of which are herein incorporated by reference in its entirety. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other advantages of the present invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:  
       FIG. 1  is a perspective view showing a surface light source device according to an exemplary embodiment of the present invention;  
       FIG. 2  is a cross-sectional view taken along the line A 1 -A 2  of  FIG. 1 ;  
       FIG. 3  is a perspective view showing a power transfer unit according to an exemplary embodiment of the present invention;  
       FIG. 4  is a perspective view showing a power transfer unit according to another exemplary embodiment of the present invention;  
       FIG. 5  is a cross-sectional view taken along the line B 1 -B 2  of  FIG. 4 ;  
       FIG. 6  is a perspective view showing a power transfer unit according to another exemplary embodiment of the present invention;  
       FIG. 7  is a perspective view showing a surface light source device according to another exemplary embodiment of the present invention;  
       FIG. 8  is a perspective view showing the surface light source device shown in  FIG. 1 ;  
       FIG. 9  is a cross-sectional view taken along the line C 1 -C 2  of  FIG. 8 ;  
       FIG. 10  is a plane view showing the space-dividing walls of the surface light source device of  FIG. 8 ;  
       FIG. 11  is a perspective view showing a surface light source device according to another exemplary embodiment of the present invention;  
       FIG. 12  is a cross-sectional view taken along the line D 1 -D 2  of  FIG. 11 ;  
       FIG. 13  is a cross-sectional view taken along the line E 1 -E 2  of  FIG. 11 ;  
       FIG. 14  is a partially enlarged view showing the power transfer unit of  FIG. 11 ;  
       FIG. 15  is a partially enlarged view showing a power transfer unit according to another exemplary embodiment of the present invention; and  
      FIG  16  is an exploded perspective view showing a liquid crystal display device according to an exemplary embodiment of the present invention;  
       FIG. 17  is an enlarged view showing a portion of a receiving container shown in  FIG. 16 ; and  
       FIG. 18  is an exploded perspective view showing a liquid crystal display device according to another exemplary embodiment of the present invention. 
    
    
     DESCRIPTION OF THE INVENTION  
      Hereinafter, the present invention will be explained in detail with reference to the accompanying figures.  
       FIG. 1  is a perspective view showing a surface light source device  1000  according to an exemplary embodiment of the present invention.  FIG. 2  is a cross-sectional view taken along the line A 1 -A 2  of  FIG. 1 . The surface light source device  1000  according to an exemplary embodiment includes a surface light source  200 , an inverter  300 , a first power transfer unit  410  and a second power transfer unit  420 .  
      The surface light source  200  includes a light source body  210 , a first external electrode  220  and a second external electrode  230 . The light source body  210  includes a first substrate  211 , a second substrate  212  facing the first substrate  211  and spaced apart from the first substrate  211 , and a sealing member  213  disposed along ends of the first and second substrates  211  and  212  to seal a discharge space  214  between the first and second substrates  211  and  212 . The discharge space  214  generates a light source using a discharge gas in response to a discharge voltage received from the external electrodes  220  and  230 .  
      The first and second substrates  211  and  212  each include a glass substrate, which transmits visual rays but blocks ultraviolet rays. The first substrate  211 , for example, has a thickness substantially identical to that of the second substrate  212 . The sealing member  213  may be formed on the first and second substrates  211  and  212  by a separate process, be integrally formed with the first substrate  211  or the second substrate  212  or be removed in case of integrally forming the first substrate  211  with the second substrate  212 .  
      The discharge space  214  may be divided into at least two discharge areas  216  by at least one space-dividing member  215 , with respect to  FIGS. 8-10  showing the surface light source device more detail. Referring  FIGS. 8-10 , a plurality of the space-dividing members  215  is arranged with spaces between each member  215  and in parallel to each other in a first direction D 1 . Each member  215  extends in a second direction D 2  substantially perpendicular to the first direction D 1 . Each of the space-dividing members  215  has, for example, a bar-shape, which is extended in the second direction D 2 . The bar-shape has a width “W” and a length “L 1 ” shorter than a length “L 2 ” of the sealing member  213  in the second direction D 2 .  
      Each space-dividing member  215  has one end  131  connected to an inner side surface of the sealing member  213  and the other end  133  placed apart from an opposite inner side surface of the sealing member  213 . Each space-dividing member  215  further includes upper and lower portions making contact with the first and second substrates  211  and  212 , respectively, by an adhesive member. The space-dividing members  215  are spaced apart from each other in a predetermined interval “d” and the first ends  131  or second ends  133  of the space-dividing members  215  are alternatively spaced apart from the sealing member  213 , so that the space-dividing members  215  are arranged in a zigzag shape.  
      Because the space-dividing members  215  are arranged in a zigzag between the first and second substrates  211  and  212  in the first direction D 1 , a connection path  119  is formed to connect the discharge areas  216 . A discharge gas is uniformly flowed into the discharge areas  216  through the connection path  119 . Alternatively, the surface light source device  1000  may have a sealed discharged area without forming the connection path  119  in which the first and second ends  131  and  133  of the space-dividing member  215  make contact with the sealing member  213 . In this case, each space-dividing member  215  may have a hole formed therethrough so as to uniformly distribute the discharge gas into the discharge areas  216 .  
      The space-dividing members  215  may be formed with a different material from or an identical material to that of the sealing member  213 . When the space-dividing members  215  are formed with an identical material to that of the sealing member  213 , the space-dividing members  215  may be formed with the sealing member  213  at the same time.  
      The first and second external electrodes  220  and  230  are formed on outer surfaces of opposite ends of the light source body  210 , respectively, and are extended in the first direction D 1 . Although  FIG. 1  shows the first and second external electrodes  220  and  230  formed on both upper and lower outer surfaces of the light source body  210 , the first and second external electrodes  220  and  230  may be formed on only an upper outer surface or only a lower outer surface of the light source body  210 .  
      The first and second external electrodes  220  and  230  receive a discharge voltage so as to make the discharge space  214  in a discharge state. For example, the first and second external electrodes  220  and  230  include a material having a superior conductivity, for example, such as copper (Cu), nickel (Ni), aluminum (A 1 ) tape, silver (Ag) paste and so on. Also, the first and second external electrodes  220  and  230  have a surface area suitable for supplying excitation energy inside the surface light source  200 .  
      The surface light source  200  further includes a first fluorescent layer  217  and a second fluorescent layer  218  facing each other. The first and second fluorescent layers  217  and  218  are formed on an inner surface of the first and second substrates  211  and  212 , respectively, except for an area on which the space-dividing members  215  are formed. Although not shown in  FIG. 9 , the surface light source  200  may further include a fluorescent layer formed on side surfaces of the space-dividing members  215 . The first and second fluorescent layers  217  and  218  emit visual rays in response to the ultraviolet rays generated by plasma in the discharge space  214 .  
      Furthermore, the surface light source  200  includes a reflecting layer  219  formed between the first substrate  211  and the first fluorescent layer  217 . The reflecting layer  219  reflects the visual rays generated by the first and second fluorescent layers  217  and  218  to the second substrate  212 . The surface light source  200  still further includes a protection layer (not shown), which may be formed between the second substrate  212  and the second fluorescent layer  218  and between the first substrate  211  and the reflecting layer  219 . The protection layer prevents mercury (Hg) that is a basis of the discharge gas injected into the discharge space  214  from being chemically reacted to the first and second substrates  211  and  212 .  
      The first and second external electrodes  220  and  230  disposed on the outer surface of the light source body  210  receive a discharge voltage from the inverter  300  ( FIG. 1 ), and are connected to the inverter  300  through the first and second power transfer units  410  and  420 , respectively. Referring to  FIGS. 1 and 2 , the first and second power transfer units  410  and  420  are combined with both ends of the light source body  210  on which the first and second external electrodes  220  and  230  are disposed. The first and second power transfer units  410  and  420 , for example, each have a clip-shaped. Particularly, the first and second power transfer units  410  and  420  clip on the first and second external electrodes  220  and  230  disposed on the light source body  210  toward the first direction D 1 , and electrically connect to the first and second external electrodes  220  and  230 , respectively.  
      The inverter  300  provides a discharge voltage to the surface light source  200  so as to generate discharge in the discharge space  214 , and the discharge voltage is applied to the surface light source  200  from the inverter  300  through first and second power lines  460  and  470  and the first and second power transfer units  410  and  420 . The first and second power lines  460  and  470  electrically connect the first and second power transfer units  410  and  420  to the inverter  300 . For example, the first and second power lines  460  and  470  may be operatably fixed to the first and second power transfer units  410  and  420  by a soldering process, respectively. Therefore, the discharge voltage generated from the inverter  300  is applied to the first and second external electrodes  220  and  230  through the first and second power lines  460  and  470  and the first and second power transfer units  410  and  420 .  
       FIG. 3  is a perspective view showing the first power transfer unit  410  shown in  FIG. 1 . In this exemplary embodiment, the second power transfer unit  420  has a structure substantially identical to that of the first power transfer unit  410 , and thus a detailed description of the second power transfer unit  420  will be omitted.  
      Still referring to  FIG. 3 , the first power transfer unit  410  includes a conductive material having an elastic force in a direction perpendicular to the first and second directions D 1  and D 2 . The first power transfer unit  410  includes a first surface  412  configured to make contact with the upper surface of the first external electrode  220  disposed on the upper outer surface of the light source body  210 , a second surface  414  downwardly extended from the first surface  412  and disposed on a side outer surface of the light source body  210 , and a third surface  416  extended from the second surface  414  and configured to make contact with the lower surface of the first external electrode  220  disposed on with the lower outer surface of the light source body  210 . The first and third surfaces  412  and  416  face each other.  
      The first power transfer unit  410  clips on the first external electrode  220  disposed on the light source body  210  while advancing from the side surface of the light source body  210  in the first direction D 1 . In order to easily clip the first power transfer unit  410  on the light source body  210 , the first and third surfaces  412  and  416  may have bent portions  417  and  418  outwardly extended from ends of the first and third surfaces  412  and  416 . The first power transfer unit  410  clips on the first external electrode  220  disposed on the light source body  210  and fixes to the first external electrode  220  and the light source body  210  with the elastic force of the first and third surfaces  412  and  416 .  
      In order to enhance the elastic force of the first and third surfaces  412  and  416 , the first power transfer unit  410  may further include a spring (not shown) interposed between the first and third surfaces  412  and  416 . Also, the first or second power transfer unit  410  or  420  may be formed in various shapes so as to enhance an engaging force between the first or second power transfer unit  410  or  420  and the light source body  210 .  
       FIG. 4  is a perspective view showing a first power transfer unit  510  according to another exemplary embodiment.  FIG. 5  is a cross-sectional view taken along the line B 1 -B 2  of  FIG. 4 .  
      Referring to  FIGS. 4 and 5 , the first power transfer unit  510  includes a first surface  512  configured to make contact with the upper surface of the first external electrode  220  disposed on the upper outer surface of the light source body  210 , a second surface  514  downwardly extended from the first surface  512  and disposed on the side outer surface of the light source body  210 , and a third surface  516  extended from the second surface  514  and configured to make contact with the lower surface of the first external electrode  220  disposed on the lower outer surface of the light source body  210 . The first and third surfaces  512  and  516  face each other. The first surface  512  includes a first bending portion  517  inwardly bent from an end of the first surface  512 , and the third surface  516  includes a second bending portion  518  inwardly bent from an end of the third surface  516 . First and second bending portions  517  and  518  extend toward each other.  
      The light source body  210  and the first external electrode  220  further each include a first engaging recess  211   a  formed at the upper surfaces thereof and engaged with the first bending portion  517  and a second engaging recess  212   a  formed at the lower surfaces thereof and engaged with the second bending portion  518 . Particularly, the first engaging recess  211   a  is formed at a position where the first bending portion  517  is placed and the second engaging recess  212   a  is formed at a position where the second bending portion  518  is placed. Thus, when the first power transfer unit  510  clips on the first external electrode  220  disposed on the light source body  210 , the first and second engaging recesses  211   a  and  212   a  are engaged with the first and second bending portions  517  and  518 , respectively, resulting in enhanced engagement between the first power transfer unit  510  and the first external electrode  220  and light source body  210 , preventing separation of the first power transfer unit  510  from the first external electrode  220  and light source body  210 .  
       FIG. 6  shows a perspective view of a first power transfer unit  610  according to another exemplary embodiment. In  FIG. 6 , a power-line connection member  618  is formed on a first power transfer unit  610  to electrically connect the first power transfer unit  610  to either of the first and second power lines  460  and  470 .  
      Still referring to  FIG. 6 , the first power transfer unit  610  includes a first surface  612  configured to make contact with the upper surface of the first external electrode  220  disposed on the upper outer surface of the light source body  210 , a second surface  614  downwardly extended from the first surface  612  and disposed on the side outer surface of the light source body  210 , a third surface  616  extended from the second surface  614  and configured to make contact with the lower surface of the first external electrode  220  disposed on the lower outer surface of the light source body  210 , and the power-line connection member  618  disposed on the second surface  614 . The first and third surfaces  612  and  616  face each other.  
      The power-line connection member  618  is formed such that the first power line  460  may be fixed to the power-line connection member  618 . For example, the power-line connection member  618  includes first and second connection portions  618   a  and  618   b  facing each other and protruding from the second surface  614 . The power-line connection member  618  may be formed by partially cutting an outwardly protruding portion from the second surface  614 . The first power line  460  is inserted and fixed between the first and second connection portions  618   a  and  618   b  of the power-line connection member  618 . Since the first power line  460  is combined with the first power transfer unit  610  via the power-line connection member  618 , a soldering process is omitted in this embodiment.  
       FIG. 7  is a perspective view showing a surface light source device according to another exemplary embodiment. In  FIG. 7 , the same reference numerals denote the same elements in  FIG. 1 , and thus the detailed descriptions of the same elements will be omitted.  
      Referring to  FIG. 7 , a surface light source device  1000  according to another exemplary embodiment of the present invention includes a surface light source  200 , a first power transfer unit  710 , a second power transfer unit  720  and an inverter  300 . The surface light source  200  includes a light source body  210  and first and second external electrodes  220  and  230  disposed on outer surfaces of opposite ends of the light source body  210 . The first and second external electrodes  220  and  230  extend in a first direction D 1 .  
      The first and second power transfer unit  710  and  720  clip on the two ends of the first and second external electrodes  220  and  230  disposed on the light source body  210  in a longitudinal direction of the first and second external electrodes  220  and  230 . For example, the first power transfer unit  710  is connected to a first end of the light source body  210  on which the first external electrode  220  is disposed, in a second direction D 2  substantially perpendicular to the first direction D 1 . The first power transfer unit  710  makes contact with the first external electrode  220  formed on the upper and lower surfaces of the light source body  210 . The second power transfer unit  720  is connected to a second end of the light source body  210  on which the second external electrode  230  is disposed, in a third direction D 3  opposite to the second direction D 2 . The second power transfer unit  720  makes contact with the second external electrode  230  formed on the upper and lower surfaces of the light source body  210 .  
      Each of the first and second power transfer units  710  and  720  has a length substantially identical to a length of each the first and second external electrodes  220  and  230 . As the contact areas between the first and second power transfer units  710  and  720  and the first and second external electrodes  220  and  230  increase, the electric or thermal property of the surface light source device  2000  is improved. Therefore, the first and second power transfer units  710  and  720  may function as an auxiliary heat sink due to the increased contact areas. Also, since the first and second power transfer units  710  and  720  may function as an absorbing member, an external impact is applied to the light source body  210  after passing through the first and second power transfer units  710  and  720  and a mechanical stability of the surface light source device  2000  is improved.  
       FIG. 11  is a perspective view showing a surface light source device according to another embodiment of the present invention.  FIG. 12  is a cross-sectional view taken along the line D 1 -D 2  of  FIG. 11 .  FIG. 13  is a cross-sectional view taken along the line E 1 -E 2  of  FIG. 11 .  
      Referring to  FIGS. 11-13 , first and second power transfer units  810  and  820  cover one end of the light source body  210 , the first external electrode  220  and the second external electrode  230 . The first and second power transfer units  810  and  820  are electrically connected to the first and second external electrodes  220  and  230 , respectively. The first and second power transfer units  810  and  820  include a conductive metal material. Each of the first and second power transfer units  810  and  820  has a clip-shaped. For example, the first power transfer unit  810  electrically connects the first external electrode  220  disposed on the first substrate  211  with the first external electrode  220  disposed on the second substrate  212 , and the second power transfer unit  820  electrically connects the second external electrode  230  disposed on the first substrate  211  with the second external electrode  230  disposed on the second substrate  212 .  
      Thus, the first and second power transfer units  810  and  820  may simultaneously apply a power voltage provided from a power supply unit such as an inverter  300  ( FIG. 1 ) to the first and second external electrodes  220  and  230 , respectively. Each of the first and second power transfer units  810  and  820  includes a fixing portion  811  protruded therefrom so as to fix a first power line  460  ( FIG. 1 ), to which the power voltage from the inverter  300  is applied.  
      The surface light source device  1000  further includes a first fluorescent layer  217  disposed on the first substrate  211 , a second fluorescent layer  218  disposed on the second substrate  212 , and a reflection layer  219  disposed between the first substrate  211  and the first fluorescent layer  217 .  
       FIG. 14  is a partially enlarged view showing the first power transfer unit  810  of  FIG. 11 . In this exemplary embodiment, the second power transfer unit  820  has a structure substantially identical to that of the first power transfer unit  810 , and thus a detailed description of the second power transfer unit  820  will be omitted.  
      Referring to  FIG. 14 , the first power transfer unit  810  includes the fixing portion  811  to fix the first power line  460  withdrawn from the inverter  300  ( FIG. 1 ). The fixing portion  811  is protruded from the first power transfer unit  810  such that the fixing portion  811  has a substantially semicircular shape, and a hole  813  is formed through a center portion of the fixing portion  811  through which the first power line  460  passes. The fixing portion  811  and the first power transfer unit  810  include the same metal material. The fixing portion  811  fixes the first power line  460  to the first power transfer unit  810  such that the power voltage provided from the inverter  300  is applied through the first power transfer unit  810  to the first external electrode  220 . Thus, the power voltage provided from the inverter  300  through the first power line  460  may be simultaneously applied to the first external electrode  220  on the outside of the first and second substrates  211  and  212 .  
      Also, when the first power line  460  is soldered to the fixing portion  811  after inserted into the hole  813  of the fixing portion  811 , workability may be improved and process time may be reduced because the power voltage is applied to the first external electrode  220  formed on the outside of the first and second substrates  211  and  212  through the first power line  460 . Although  FIGS. 11-14  show the fixing portion  811  formed on an upper portion of the first power transfer unit  810 , the fixing portion  811  may be formed on a side portion or a lower portion of the first power transfer unit  810 .  
       FIG. 15  is a partially enlarged view showing a power transfer unit according to another exemplary embodiment of the present invention. Referring to  FIG. 15 , a first power transfer unit  910  includes a first fixing portion  911  and a second fixing portion  912  so as to fix a first power line  460  to the first power transfer unit  910 . The first and second fixing portions  911  and  912  are provided on the first power transfer unit  910  in parallel to each other in a longitudinal direction of the first power transfer unit  910 .  
      The first fixing portion  911  is provided on the first power transfer unit  910  by partially cutting the first power transfer unit  910  and bending the cut portion, thereby providing a wing  913  that receives an inner wire of the first power line  460 . When a predetermined force is applied to the wing  913  after the inner wire of the first power line  460  is received into the wing  913 , the wing  913  grips the inner wire of the first power line  460 . Since the first fixing portion  911  makes contact with the inner wire of the first power line  460  and fixes the inner wire of the first power line  460  to the first power transfer unit  910 , the power voltage provided from the inverter  300  may be applied to the first external electrode  220  formed on the outside of the first and second substrates  211  and  212 .  
      The second fixing portion  912  is provided on the first power transfer unit  910  by partially cutting the first power transfer unit  910  and bending the cut portion, thereby providing a wing  913  that receives a cable sheath of the first power line  460 . The second fixing portion  912  fixes the first power line  460  to the first power transfer unit  910  such that the first power line  460  is not separated from the first power transfer unit  910  due to an external impact. The first and second fixing portions  911  and  912  may be formed on an upper side portion, a side portion or a lower portion of the first power transfer unit  910 .  
      Thus, the power voltage provided from the inverter  300  through the first power line  460  may be simultaneously applied to the first external electrode  220  formed on the outside of the first and second substrates  211  and  212 . Also, workability may be improved and process time may be reduced of the surface light source device  1000  because the power voltage is applied to the first external electrode  220  on the outside of the first and second substrates  211  and  212  through the first power line  460 .  
       FIG. 16  is an exploded perspective view showing a liquid crystal display device according to an exemplary embodiment of the present invention.  FIG. 17  is an enlarged view showing a portion of a receiving container shown in  FIG. 16 .  
      Referring to  FIGS. 16 and 17 , a liquid crystal display device  2000  includes the surface light source  200 , the first and second power transfer units  410  and  420 , a receiving container  1100 , the inverter  300  and a display unit  1200 . In this exemplary embodiment, the surface light source  200 , the inverter  300 , the first power transfer unit  410  and the second power transfer unit  420  have structures substantially identical to those of the surface light source  200 , the inverter  300 , the first power transfer unit  410  and the power transfer unit  420  of  FIG. 1 , and thus the detailed descriptions of the surface light source  200 , the inverter  300 , the first power transfer unit  410  and the second power transfer unit  420  will be omitted.  
      The display unit  1200  includes a liquid crystal display panel  1210  that displays an image, and a data printed circuit board  1220  and a gate printed circuit board  1230  that generates driving signals to drive the liquid crystal display panel  1210 . The data and gate printed circuit boards  1220  and  1230  are electrically connected to the liquid crystal display panel  1210  via a data tape carrier package (data TCP)  1240  and a gate tape carrier package (gate TCP)  1250 .  
      The liquid crystal display panel  1210  includes a thin film transistor (TFT) substrate  1212 , a color filter substrate  1214  combined with the TFT substrate  1212 , and liquid crystal  1216  interposed between the TFT substrate  1212  and the color filter substrate  1214 . The TFT substrate  1212  includes a transparent glass substrate on which TFTs are arranged in a matrix configuration. Each of the TFTs includes a source electrode connected to a data line, a gate electrode connected to a gate line and a drain electrode connected to a pixel electrode (not shown) including a transparent conductive material. The color filter substrate  1214  is a substrate in which red, green and blue pixels (not shown) are formed in a thin film process. The color filter substrate  1214  includes a transparent conductive common electrode (not shown) formed therein.  
      The receiving container  1100  includes a bottom surface  1110  and a plurality of sidewalls  1120  extended from edges of the bottom surface  1110  so as to provide a receiving space. The surface light source  200  is received into the receiving space of the receiving container  1100 . The sidewalls  1120  are extended in a direction substantially perpendicular to the bottom surface  1110 , and make contact with four side surfaces of the surface light source  200 , thereby preventing the separation of the surface light source  200  from the receiving container  1100 . The receiving container  1100  may further include an insulating member (not shown) between the bottom surface  1110  and the surface light source  200 . When the receiving container  1100  is formed with a metal, the insulating member prevents the electrodes of the surface light source  200  from making contact with the receiving container  1100 .  
      The receiving container  1100  further includes a receiving recess  1130  having a shape corresponding to a shape of the first and second power transfer units  410  and  420 . The receiving recess  1130  is formed at the bottom surface  1110  and the sidewalls  1120  corresponding to an area into which the first and second power transfer units  410  and  420  are placed. When the surface light source  200 , to which the first and second power transfer units  410  and  420  are connected, is received into the receiving container  1100 , the first and second power transfer units  410  and  420  are received into the receiving recess  1130 , and also the lower surface and side surfaces of the light source body  210  make contact with the bottom surface  1110  and the sidewalls  1120  of the receiving container  1100 , respectively.  
      The receiving container  1100  further includes an opening  1140  formed through the bottom surface  1110 . The first and second power lines  460  and  470  enter into and exit from the opening  1140 . The opening  1140  is formed adjacent to the receiving recess  1130 . The first and second power lines  460  and  470  connected to the first and second power transfer units  410  and  420  are withdrawn from the receiving container  1100  through the opening  1140 , and are electrically connected to the inverter  300 .  
      The liquid crystal display device  2000  further includes an optical plate  1260  and a top chassis  1270 . The optical plate  1260  is disposed between the surface light source  200  and the liquid crystal display panel  1200 . The optical plate  1260  enhances brightness and uniformity of light emitted from the surface light source  200 . For example, the optical plate  1260  may include a diffusion sheet that diffuses the light and a prism sheet that condenses the light. The liquid crystal display device  2000  may further include a mold frame (not shown) between the light source body  200  and the optical plate  1260  in order to support the optical plate  1260 .  
      The top chassis  1270  is combined with the receiving container  1100  while surrounding edges of the liquid crystal display panel  1210 . The top chassis  1270  prevents breakage of the liquid crystal display panel  1210  due to an external impact, and prevents from the separation of the liquid crystal display panel  1210  from the receiving container  1100 .  
       FIG. 18  is an exploded perspective view showing a liquid crystal display device according to the other exemplary embodiment of the present invention. In  FIG. 18 , the surface light source  200 , the inverter  300 , the first power transfer unit  410  and the second power transfer unit  420  have structures substantially identical to those of the surface light source  200 , the inverter  300 , the first power transfer unit  410  and the power transfer unit  420  of  FIG. 11 . The same reference numerals denote the same elements in  FIGS. 1 and 16 , and thus the detailed descriptions of the same elements will be omitted.  
      Referring to  FIG. 18 , the discharge voltage generated from the inverter  300  is applied to the first and second power transfer units  810  and  820  ( FIG. 11 ) through the first and second power lines  460  and  470 , respectively. Since the inner wire of the first and second power lines  460  and  470  are fixed to the first and second power transfer units  810  and  820  by the fixing portion  811 , the discharge voltage applied to the first and second power transfer units  810  and  820  is be applied to the surface light source device  1100  through the first and second external electrodes  220  and  230 . Therefore, the first and second power lines  460  and  470  are electrically connected to the first and second external electrodes  220  and  230 .  
      Thus, the discharge voltage is applied to the first and second external electrodes  220  and  230  through the first and second power transfer units  810  and  820 . In response to the discharge voltage applied to the discharge areas  216 , the surface light source device  1000  performs a discharge operation. The first and second power lines  460  and  470  may be directly soldered to the first and second external electrodes  220  and  230 , respectively.  
      Since a surface light source device according to exemplary embodiments of the present disclosure include first and second external electrodes disposed on an outer surface of a light source body and first and second power transfer units connecting the first and second external electrodes to an inverter, electrical and mechanical properties of the surface light source device is improved. Further, the surface light source device provides the light having uniform brightness distribution. Furthermore, the surface light source device uses one power line, instead of a plurality of wires withdrawn from an inverter. Thus, workability is improved and process time is reduced.  
      Although the exemplary embodiments of the present invention have been described, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art within the spirit and scope of the present invention as hereinafter claimed.