Patent Publication Number: US-2010118231-A1

Title: Liquid crystal display device

Description:
TECHNICAL FIELD 
     The embodiment relates to a liquid crystal display device. 
     BACKGROUND ART 
     As information processing technology has been developed, flat display devices such as LCDs, PDPs or AMOLEDs have been extensively used. Since such flat display devices have been extensively used for portable devices, they must have a slim structure. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     The embodiment provides an LCD having a slim structure. 
     Technical Solution 
     According to an embodiment, an LCD comprises: a first substrate; a second substrate facing the first substrate; a liquid crystal layer interposed between the first substrate and the second substrate; and a light source disposed at a lateral side of the second substrate to emit light toward the second substrate. 
     According to an embodiment, an LCD comprises: a liquid crystal panel including first and second substrates facing each other; a connection substrate connected with the second substrate; and a light source mounted on the connection substrate to emit light toward a lateral side of the second substrate. 
     According to an embodiment, an LCD comprises: a liquid crystal panel; a polarizing layer disposed inside the liquid crystal panel; a scattering member adhering to a bottom surface of the liquid crystal panel; and a light source disposed at a lateral side of the liquid crystal panel. 
     Advantageous Effects 
     An LCD according to the embodiment displays an image by receiving light through a lateral side of a liquid crystal panel, i.e. a lateral side of a substrate included in the liquid crystal panel. 
     Accordingly, the LCD according to the embodiment does not require a member for guiding light, which is generated from a light source, in a horizontal direction. Thus, the LCD according to the embodiment has a slim structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exploded perspective view of an LCD according to a first embodiment; 
         FIG. 2  illustrates a sectional view of one section of an LCD according to a first embodiment; 
         FIG. 3  illustrates a sectional view of one section of a liquid crystal panel according to a second embodiment; 
         FIG. 4  illustrates a sectional view of one section of an LCD according to a third embodiment; and 
         FIG. 5  illustrates a sectional view of one section of an LCD according to a fourth embodiment. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     In the description of an embodiment, it will be understood that, when a panel, a substrate, a layer (or film), a region, a pattern, a sheet, a member or a structure is referred to as being “on” or “under” another panel, another substrate, another layer (or film), another region, another pad, another member, another sheet or another structure, it can be “directly” or “indirectly” on the other panel, substrate, layer (or film), region, sheet, member or structure, or one or more intervening layers may also be present. Further, “on” or “under” of each layer is determined based on the drawing. 
     Further, the thickness or size of layers shown in the drawings can be simplified or exaggerated for the purpose of clear explanation. In addition, the size of each element may be reduced or magnified from the real size thereof. 
       FIG. 1  illustrates an exploded perspective view of an LCD according to a first embodiment and  FIG. 2  illustrates a sectional view of one section of an LCD according to a first embodiment. 
     Referring to  FIG. 1  and  FIG. 2 , the LCD comprises a case  100 , a reflective sheet  200 , an optical sheet  300 , a liquid crystal panel  400 , a connection substrate  500 , a light emitting diode  600  and a scattering member  700 . 
     The case  100  receives the reflective sheet  200 , the optical sheet  300 , the liquid crystal panel  400 , the connection substrate  500 , the light emitting diode  600  and the scattering member  700 . 
     The reflective sheet  200  is disposed inside the case  100  to reflect light, which is generated from the light emitting diode  600 , in the upward direction. 
     The optical sheet  300  improves properties of transmitted light. The optical sheet  300  comprises a first prism sheet  310 , a polarizing sheet  320  and a second prism sheet  330 . 
     The first prism sheet  310  is disposed below the liquid crystal panel  400  and on the reflective sheet  200 . In more detail, the first prism sheet  310  is interposed between the scattering member  700  and the reflective sheet  200 . Further, the first prism sheet  310  makes contact with the scattering member  700  and the reflective sheet  200 . 
     The first prism sheet  310  comprises a first prism pattern extending in the first direction. The first prism sheet  310  increases brightness of the LCD by refracting the transmitted light or guiding the transmitted light toward the liquid crystal panel  400 . 
     The polarizing sheet  320  is disposed on the liquid crystal panel  400  to polarize the transmitted light in a predetermined direction. The polarizing sheet  320  can closely make contact with the liquid crystal panel  400 . 
     The second prism sheet  330  is disposed on the polarizing sheet  320 . The second prism sheet  330  comprises a second prism pattern extending in the second direction. Similarly to the first prism sheet  310 , the second prism sheet  330  increases brightness of the LCD by refracting the transmitted light or guiding the transmitted light toward the liquid crystal panel  400 . 
     The liquid crystal panel  400  is disposed inside the case  100  to adjust the intensity of the transmitted light in each pixel that is an image display unit. The liquid crystal panel  400  comprises a TFT substrate  410 , a color filter substrate  420  and a liquid crystal layer  430 . 
     The TFT substrate  410  forms the electric field in each pixel by receiving a signal through the connection substrate  500 . The TFT substrate  410  comprises a base substrate  411 , a polarizing layer  412  and a TFT layer  413 . 
     The base substrate  411  is a glass substrate or a quartz substrate. The base substrate  411  is transparent or translucent. 
     The polarizing layer  412  is disposed on the base substrate  411 . In more detail, the polarizing layer  412  is formed by coating the entire surface of the base substrate  411 . The polarizing layer  412  polarizes the transmitted light in a predetermined direction. 
     For example, the polarizing layer  412  can be formed by coating a TCF (thin crystal film) on the base substrate  411 . 
     In more detail, the polarizing layer  412  can be formed through the following process. 
     First, the base substrate  411  is cleaned. Next, the base substrate  411  is subject to plasma processing. 
     Then, the TCF is coated on the base substrate  411  through a FAS slot die coating method, a Mayer rod coating method and the like. At this time, a polarizing direction of the TCF is determined based on the coating direction. 
     The coated TCF is patterned by deionized water and the like. 
     Then, the TCF is stabilized by BaCl 2  and the like. 
     Last, the stabilized TCF is subject to heat treatment at the temperature of about 60° to 130°. 
     Further, the polarizing layer  412  comprises a reflective polarizing film such as a DBEF (dual brightness enhancement film). The reflective polarizing film polarizes a part of the transmitted light and reflect a remaining part of the transmitted light. 
     For example, the reflective polarizing film comprises several hundreds of compressed layers having refraction indices different from each other. 
     The TFT layer  413  is formed on the polarizing layer  412 . The TFT layer  413  comprises a plurality of lines, a plurality of thin film transistors and pixel electrodes. The TFT layer  413  forms the electric field in each pixel by receiving an electrical signal through the connection substrate  500 . 
     Further, the polarizing layer  412  may be disposed on the TFT layer  413 . 
     The color filter substrate  420  is disposed above the TFT substrate  410  while facing the TFT substrate  410 . The color filter substrate  420  comprises a plurality of color filters. The color filter substrate  420  is coupled with the TFT substrate  410  by a sealing member  440 . 
     The liquid crystal layer  430  is interposed between the TFT substrate  410  and the color filter substrate  420 . The liquid crystal layer  430  comprises liquid crystal. 
     Further, a driver IC  401  is mounted on the TFT layer  413 . 
     The connection substrate  500  is electrically and physically connected with the TFT substrate  410 . For example, the connection substrate  500  is electrically connected with lines formed on the TFT layer  413 . 
     The connection substrate  500  is prepared in the form of a flexible circuit board. The connection substrate  500  is electrically connected with a main substrate for driving the LCD. 
     The light emitting diode  600  is directly mounted on the connection substrate  500 . Further, the light emitting diode  600  is disposed at a lateral side of the liquid crystal panel  400 . In more detail, the light emitting diode  600  is disposed at a lateral side of the TFT substrate  410 , i.e. the base substrate  411 . 
     The height of the light emitting diode  600  is substantially identical to or greater than the thickness of the TFT substrate  410 . 
     The light emitting diode  600  generates light to emit the light toward the lateral side of the liquid crystal panel  400 . In more detail, the light emitting diode  600  emits the light toward the lateral side of the base substrate  411 . A light emitting surface  610 , through which the light of the light emitting diode  600  is emitted, faces the lateral side of the base substrate  411 . 
     The scattering member  700  is disposed below the liquid crystal panel  400 . In detail, the scattering member  700  is disposed below the base substrate  411 . The scattering member  700  comprises a base film  710  and a protrusion pattern  720 . 
     The base film  710  is transparent. For example, resin is used for the base film  710 . 
     The protrusion pattern  720  protrudes from the base film  710 . The protrusion pattern  720  can be integrally formed with the base film  710 . The number of protrusions per a unit area of the protrusion pattern  720  (hereinafter, referred to as protrusion density) may vary depending on the position in the protrusion pattern  720 . 
     For example, the protrusion density is increased in the second direction. Further, the protrusion density may be gradually increased proportionally to the distance relative to the light emitting diode  600 . 
     The scattering member  700  is disposed such that the protrusion pattern  720  faces the liquid crystal panel  400 , and adheres to the base substrate  411  by an adhesive member  800 . In detail, the adhesive member  800  adheres to the scattering member  700  while adhering to the base substrate  411 . 
     The adhesive member  800  has a refraction index substantially identical to that of the base substrate  411 . In detail, the refraction index of the adhesive member  800  corresponds to that of the base substrate  411 . 
     Thus, light incident into the base substrate  411  can be easily incident into the adhesive member  800 . Further, the light incident into the adhesive member  800  is scattered by the protrusion pattern  720 . 
     In detail, since the refraction index of the adhesive member  800  is substantially identical to that of the base substrate  411 , the light incident through the lateral side of the base substrate  411  is easily scattered. 
     According to another embodiment, the refraction index of the adhesive member  800  may be greater than that of the base substrate  411 . 
     For example, the adhesive member  800  may use PSA (pressure sensitive adhesive) and the like. 
     The light emitted from the light emitting diode  600  is incident through the lateral side of the base substrate  411 . The incident light is scattered by the scattering member  700  and then is totally reflected by the base substrate  411 . 
     A part of the incident light is emitted upward and the other part of the incident light is emitted downward. At this time, the light emitted upward is polarized by passing through the polarizing layer  412 , and then is used for displaying an image. 
     Further, the light emitted downward passes through the first prism sheet  310 , is reflected by the reflective sheet  200 , and then passes through the first prism sheet  310 . 
     The light passing through the first prism sheet  310  twice has properties improved by the first prism sheet  310 , and is used for displaying an image. 
     According to the LCD of the embodiment, the light is incident through the lateral side of the base substrate  411  and an image is displayed by the incident light, so that a light guide plate and the like is not required. 
     Thus, the LCD according to the embodiment has a slim structure as compared with an existing LCD additionally using a light guide plate. 
     Further, the polarizing layer  412  is disposed inside the liquid crystal panel  400  and the first prism sheet  310  is interposed between the scattering member  700  and the reflective sheet  200 , so that the LCD according to the embodiment can display high quality images. 
     Further, a driving signal is applied to the liquid crystal panel  400  and the light emitting diode  600  through the connection substrate  500 . In other words, the driving signal is applied to the liquid crystal panel  400  and the light emitting diode  600  through one substrate. 
     Thus, the LCD according to the embodiment can be formed through a simple process. 
     In addition, the light emitting diode  600  is mounted on the connection substrate  500 , so that the light emitting diode  600  can be disposed adjacently to the lateral side of the base substrate  411 . Thus, light leaked from the light emitting diode  600  can be reduced. 
     Consequently, the LCD according to the embodiment has improved brightness. 
       FIG. 3  is a sectional view showing one section of an LCD according to another embodiment. The present embodiment will further describe a transflective layer with reference to the aforementioned embodiment. 
     Referring to  FIG. 3 , the liquid crystal panel  400  comprises a transflective layer  414 . The transflective layer  414  is interposed between the polarizing layer  412  and the base substrate  411 . The transflective layer  414  allows a part of incident light to pass therethrough and reflect remaining incident light. 
     The transflective layer  414  is formed by laminating a plurality of transparent layers having refraction indices different from each other. 
     Light incident into the base film  710  is totally reflected by the base film  710 , and a part of the light is totally reflected in the transflective layer  414 . 
     Thus, the light incident into the base film  710  can be uniformly emitted upward, so that the LCD according to the embodiment has improved brightness uniformity. 
       FIGS. 4 and 5  are sectional views showing LCDs according to further another embodiment. The present embodiment will further describe a position of an optical sheet with reference to the aforementioned embodiments. 
     Referring to  FIG. 4 , the first prism sheet  310  is interposed between the polarizing sheet  320  and the liquid crystal panel  400 . At this time, the first prism sheet  310 , the polarizing sheet  320  and the second prism sheet  330  can closely make contact with each other. 
     Referring to  FIG. 5 , the first prism sheet  310  can be interposed between the polarizing sheet  320  and the second prism sheet  330 . 
     Since the first prism sheet  310  is disposed on the liquid crystal panel, all lights for displaying images pass through the first prism sheet  310 . 
     Thus, the LCD according to the embodiment can display high quality images. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. 
     INDUSTRIAL APPLICABILITY 
     The LCD according to the embodiment is used for displaying images.