Abstract:
In an LCD apparatus having an optical member, the optical member has a base body having a light incident surface and a light emitting surface faced the light incident surface. A first resin layer is formed on the light emitting surface and a light diffusing pattern is uniformly formed on the first resin layer so as to diffuse a first light and emit a second light. Accordingly, the LCD apparatus can improve display quality and can be fabricated in low-cost manufacture. Also, since the light diffusing pattern is formed with a curable material, the light diffusing pattern can have various shapes and superior reproducibility.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application relies for priority upon Korean Patent Application No. 2002-60804 filed on Oct. 5, 2002, the contents of which are herein incorporated by reference in its entirety.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an optical member, a method of fabricating the same and an LCD (Liquid Crystal Display) apparatus having the same, and more particularly to an optical member that has high display quality and may be manufactured at a low-cost, a method of fabricating the same and an LCD apparatus having the same.  
           [0004]    2. Description of the Related Art  
           [0005]    In general, an LCD apparatus displays an image using a liquid crystal. A liquid crystal applied to an LCD apparatus has electrical property, for example, such as an arrangement is varied according to an electric field applied thereto and optical property, for example, such as light transmittance is varied according to the arrangement of the liquid crystal.  
           [0006]    In order to display an image using a liquid crystal, an LCD apparatus includes a light supply module for generating light and a display module for changing the light emitted from the light supply module into image light having image information.  
           [0007]    The LCD apparatus further includes a module for changing a light distribution of the light emitted from the light supply module or improving brightness of the light emitted from the light supply module. The module is disposed between the light supply module and the display module.  
           [0008]    In detail, the module includes a light guide plate, a diffusion sheet and a prism sheet. The light guide plate changes the light distribution of a line light source emitted from the light supply module into a light distribution of a surface light source. The diffusion sheet is disposed on the light guide plate and allows the light emitted from the light guide plate to have a uniform brightness distribution. The diffusion sheet includes beads distributed on a transparent substrate so as to scatter or diffuse the light emitted from the light guide plate.  
           [0009]    However, beads may be nonuniformly distributed on the diffusion sheet since beads are very minute. In case that beads are nonuniformly distributed, the brightness distribution of the light emitted from the diffusion sheet is not uniform, thereby deteriorating display quality of LCD apparatus.  
         BRIEF SUMMARY OF THE INVENTION  
         [0010]    The present invention provides an optical member for generating light having a uniform brightness distribution.  
           [0011]    Also, the present invention provides a method of fabricating the above optical member.  
           [0012]    Also, the present invention provides an LCD apparatus having the above optical member.  
           [0013]    In one aspect of the invention, an optical member includes a base body and a light diffusing layer formed on the base body.  
           [0014]    The base body has a light incident surface for receiving a first light and a light emitting surface for emitting the first light, which faces the light incident surface. The light diffusing layer has a first resin layer disposed on the light emitting surface and a light diffusing pattern disposed on the first resin layer so as to diffuse the first light emitted from the light emitting surface and to emit a second light.  
           [0015]    In another aspect of the invention, in a method of fabricating an optical member, a first resin layer is formed on a light emitting surface of a base body having a light incident surface for receiving a first light and the light emitting surface for emitting the first light, which faces the light incident surface. A light diffusing pattern having a hemispherical shape is formed on the first resin layer so as to diffuse the first light emitted from the light emitting surface and to emit a second light, the light diffusing pattern having a hemispherical shape. The first resin layer is cured through a curing process.  
           [0016]    In further aspect of the invention, an LCD apparatus includes a light supply module for generating a first light, an optical member for diffusing the first light and emitting a second light and an LCD panel assembly for displaying an image using the second light.  
           [0017]    The optical member includes a base body having a light incident surface for receiving the first light and a light emitting surface facing the light incident surface, a first resin layer formed on the light emitting surface, and a light diffusing layer having a light diffusing pattern formed on the first resin layer, for diffusing the first light emitted from the light emitting surface and emitting a second light.  
           [0018]    According to the present invention, the light diffusing pattern formed on the optical member changes a light having a nonuniform brightness distribution into a light having a uniform brightness distribution. Thus, the LCD apparatus having the optical member can improve display quality and can be fabricated at a low-cost since the optical member does not need beads.  
           [0019]    Also, since the light diffusing pattern is formed with a curable material, the light diffusing pattern can have various shapes and superior reproducibility. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    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:  
         [0021]    [0021]FIG. 1 is a perspective view showing an optical member according to an exemplary embodiment of the present invention;  
         [0022]    [0022]FIGS. 2A and 2B are views showing a base body shown in FIG. 1;  
         [0023]    [0023]FIGS. 3A and 3B are graphs showing heat properties of a base body shown in FIG. 1;  
         [0024]    [0024]FIG. 4 is a cross-sectional view taken along the lines A-A′ for showing an optical member shown in FIG. 1;  
         [0025]    [0025]FIG. 5 is a partially enlarged view showing a portion “B” in FIG. 4;  
         [0026]    [0026]FIG. 6 is a scanning-electron-microscopy (SEM) specimen showing a light diffusing pattern according to an exemplary embodiment of the present invention;  
         [0027]    [0027]FIGS. 7A to  7 D are views for illustrating a method of fabricating an optical member according to an exemplary embodiment of the present invention;  
         [0028]    [0028]FIGS. 8A to  8 C are views for illustrating a method of fabricating an optical member according to another exemplary embodiment of the present invention;  
         [0029]    [0029]FIGS. 9A to  9 E are views for illustrating a method of manufacturing a roller according to an exemplary embodiment of the present invention; and  
         [0030]    [0030]FIG. 10 is a schematic view showing an LCD apparatus according to an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]    [0031]FIG. 1 is a perspective view showing an optical member according to an exemplary embodiment of the present invention.  
         [0032]    Referring to FIG. 1, an optical member  100  includes an optical sheet that changes light having a nonuniform brightness distribution into light having a uniform brightness distribution. For this purpose, the optical member  100  includes a base body  110  and a light diffusing layer  150 .  
         [0033]    The base body  110  has a shape of a rectangular plate or a rectangular sheet having a length longer than a width thereof and comprises polyester having a high light transmittance.  
         [0034]    [0034]FIG. 2A is a plan view showing the base body  110  shown in FIG. 1, and FIG. 2B is a sectional view showing the base body  110  shown in FIG. 1.  
         [0035]    Referring to FIGS. 2A and 2B, the base body  110  includes a first surface  111 , a second surface  112 , a third surface  113 , a fourth surface  114 , a light incident surface  115  and a light emitting surface  116 .  
         [0036]    Particularly, the first and second surfaces  111  and  112  face the third and fourth surfaces  113  and  114 , respectively, and the light incident surface  115  faces the light emitting surface  116 . The first to fourth surfaces  111 ,  112 ,  113  and  114  are connected between the light incident surface  115  and the light emitting surface  116 . The base body  110  has high light transmittance so as to emit a first light  510  that is incident through the light incident surface  115  without changing optical properties of the first light  510 .  
         [0037]    The base body  110  may have various shapes in association with an installation position of a light source (not shown) that emits the first light  510 . The base body  110  may be deformed by heat generated from the light source (not shown) and the heat generated from the light source (not shown) may cause wrinkle on the base body  110 . As a result, the base body  110  wrinkled by the heat deteriorates display quality of the LCD apparatus.  
         [0038]    [0038]FIGS. 3A and 3B are graphs showing heat properties of the base body  110  shown in FIG. 1.  
         [0039]    In FIG. 3A, a graph GA represents a length variation of the base body  110  while the base body  110  is heated and a graph GB represents a length variation of the base body  110  while the base body  110  is cooled.  
         [0040]    As shown in FIG. 3A, when the base body  110  is successively heated from temperature “A” to temperature “B”, the base body  110  is expanded along the graph GA as represented in quadratic curve. The base body  110  is successively expanded while the temperature “A” reaches the temperature “B” and contracted while the temperature “B” reaches temperature “C” even though the temperature “B” rises to the temperature “C”, so the expanded length of the base body  110  is longest at the temperature “B”.  
         [0041]    When the base body  110  is successively cooled from the temperature “C” to the temperature “A”, the base body  110  has a length different from a length before the base body  110  is heated. The difference between the expanded length and the contracted length of the base body  110  is as shown in reference numeral “L” of FIG. 3A. This means that the base body  110  is permanently deformed when the temperature applied to the base body  110  exceeds a specified temperature.  
         [0042]    Recently, a length of lamp applied to an LCD apparatus and a light amount thereof gradually increases according to a scaled-up size of the LCD apparatus. As a result, a heat amount generated from the lamp increases, so that the base body  110  applied to the LCD apparatus may be wrinkled due to the increased heat amount generated from the lamp.  
         [0043]    Referring to FIG. 3B, when the heat-treated base body  110  is successively heated from the temperature “A” to the temperature “C”, the base body  110  is expanded in proportion to the temperature raised from the temperature “A” to the temperature “C”. On the contrary, when the heat-treated base body  110  is cooled from the temperature “C” to the temperature “A”, the length of the base body  110  returns to an initial state before the base body  110  is heated. That is, the expanded length of the base body  110  is identical to the contracted length of the base body  110 .  
         [0044]    The heat-treated base body  110  that comprises polyester does not wrinkle by the heat generated from the lamp, thereby preventing the deterioration of display quality of the LCD apparatus. As shown in FIG. 1, the light diffusing layer  150  is disposed on the heat-treated base body  110 .  
         [0045]    [0045]FIG. 4 is a cross-sectional view taken along the lines A-A′ for showing an optical member shown in FIG. 1, and FIG. 5 is a partially enlarged view showing a portion “B” shown in FIG. 4.  
         [0046]    Referring to FIGS. 4 and 5, the light diffusing layer  150  is disposed on the light emitting surface  116  of the base body  110 . The light diffusing layer  150  includes a first resin layer  130  and a light diffusing pattern  135 .  
         [0047]    The first resin layer  130  may be comprised of a curable material that is gradually cured in accordance with the passage of time or rapidly cured under a specified condition.  
         [0048]    In this exemplary embodiment, the first resin layer  130  is rapidly cured under the specified condition. That is, the first resin layer  130  is cured by exposure to ultraviolet rays, so the first resin layer  130  includes an ultraviolet-curable material.  
         [0049]    Also, an expansion ratio and a contraction ratio of the first resin layer  130  are identical to those of the heat-treated base body  110  as described above. If the expansion ratio and contraction ratio of the first resin layer  130  are not identical to those of the heat-treated base body  110 , the first resin layer  130  attached on the heat-treated base body  110  may be cracked or torn while the heat-treated base body  110  is expanded or contracted by the heat generated from the lamp.  
         [0050]    [0050]FIG. 6 is a scanning-electron-microscopy (SEM) specimen showing a light diffusing pattern according to an exemplary embodiment of the present invention.  
         [0051]    Referring to FIG. 6, the light diffusing pattern  135  is formed on a surface of the first resin layer  130  by using a stamp method.  
         [0052]    The light diffusing pattern  135  has a hemispherical shape uniformly formed on the surface of the first resin layer  130 . The first light  510  passing through the base body  110  reaches the light diffusing pattern  135  and is diffused while passing through a spherical surface of the light diffusing pattern  135 . Hereinafter, the first light  510  diffused by the light diffusing pattern  135  is defined as a second light  420 .  
         [0053]    In this exemplary embodiment, with consideration for using the stamp method so as to form the light diffusing pattern  135 , the light diffusing pattern  135  may have various shapes, for example, such as a convex pyramid, a concave hemisphere or a concave pyramid.  
         [0054]    As shown in FIG. 5, the optical member  100  further includes a layer  140  having a second resin layer  142  disposed on the light incident surface  115  and a protrusion  144  disposed on the second resin layer  142  so as to prevent the second resin layer  142  from making contact with a member adjacent to the optical member  100 .  
         [0055]    The second resin layer  142  is comprised of the curable material that is gradually cured in accordance with the passage of time or rapidly cured under the specified condition. In this exemplary embodiment, the second resin layer  142  includes the ultraviolet-curable material so as to be cured by exposure to ultraviolet rays.  
         [0056]    Also, an expansion ratio and a contraction ratio of the second resin layer  142  are identical to those of the heat-treated base body  110 . If the expansion ratio and contraction ratio of the second resin layer  142  are not identical to those of the heat-treated base body  110 , the second resin layer  142  attached on the heat-treated base body  110  may be cracked or torn while the heat-treated base body  110  is expanded or contracted by the heat generated from the lamp.  
         [0057]    Furthermore, an expansion ratio and a contraction ratio of the second resin layer  142  are identical to those of the first resin layer  130 . If the expansion ratio and contraction ratio of the second resin layer  142  are not identical to those of the first resin layer  130 , the base body  110  may be bent due to differences of the expansion and contraction ratios between the first and second resin layers  130  and  142  while the base body  110  is expanded or contracted.  
         [0058]    The protrusion  144  is formed on a surface of the second resin layer  142  in a matrix configuration and protruded from the surface of the second resin layer  142 . The protrusion  144  may have various shapes, for example, such as a hemispherical shape and a polygonal shape since the protrusion  144  is formed using the stamp method.  
         [0059]    Hereinafter, a method of fabricating the optical member according to an exemplary embodiment of the present invention will be illustrated with reference to the accompanying drawings.  
         [0060]    [0060]FIGS. 7A to  7 D are views for illustrating a method of fabricating an optical member according to an exemplary embodiment of the present invention.  
         [0061]    Referring to FIG. 7A, the base body  110  is selectively heat-treated according to a material contained into the base body  110  before forming the first resin layer  130  (see FIG. 7B) thereon. That is, the heat treatment with respect to the base body  110  is selectively performed when the expansion ratio and the contraction ratio are not identical to each other.  
         [0062]    Referring to FIG. 7B, the first resin layer  130  is formed on the light emitting surface  116  of the base body  110  in a thin film. In this exemplary embodiment, the first resin layer  130  includes the curable material cured by exposure to the ultraviolet rays.  
         [0063]    Referring to FIG. 7C, a first roller  370 , on which a first transfer pattern  130  having a hemispherical shape that is reversed with respect to the light diffusing pattern  135  (see FIG. 4) is formed, is disposed on the first resin layer  130 . The first roller  370  is rolled along the surface of the first resin layer  130  so as to form the light diffusing pattern  135  on the first resin layer  130 . After the light diffusing pattern  135  is formed on the first resin layer  130  by rolling the first roller  370 , the first resin layer  130  and the light diffusing pattern  135  formed on the first resin layer are exposed to the ultraviolet rays, thereby curing the first resin layer  130  and the light diffusing pattern  135 .  
         [0064]    Referring to FIG. 7D, after curing the first resin layer  130  and the light diffusing pattern  135 , the second resin layer  140  having the curable material cured by exposure to the ultraviolet rays is formed on the light incident surface  115  of the base body  110 . A second roller  380 , on which a second transfer pattern  385  having a reversed shape with respect to the protrusion  144  is formed, is disposed on the second resin layer  140 . The second roller  380  is rolled along the surface of the second resin layer  140  so as to form the protrusion  144  on the surface of the second resin layer  140 , thereby preventing the base body  110  from making contact with a member adjacent to the base body  110 , for example, such as a light guide plate (not shown). The second resin layer  140  and the protrusion  144  are cured by exposure to the ultraviolet rays.  
         [0065]    [0065]FIGS. 8A to  8 C are views for illustrating a method of fabricating an optical member according to another exemplary embodiment of the present invention.  
         [0066]    Referring to FIG. 8A, a first resin layer  130  is formed on a light emitting surface  116  of a base body  110  and a second resin layer  140  is formed on a light incident surface  115 . In this exemplary embodiment, the first and second resin layers  130  and  140  include a curable material cured by exposure to an ultraviolet rays.  
         [0067]    Referring to FIGS. 8B and 8C, a first roller  370  is disposed on the first resin layer  130  and a second roller  380  is disposed on the second resin layer  140 .  
         [0068]    The first roller  370  includes a first transfer pattern  375  which is closely formed on the first rolled  370  and the second roller  380  includes a second transfer pattern  385  which is separated from each other in a predetermined distance. The first and second transfer patterns  375  and  385  has a hemispherical shape that is reversed with respect to a light diffusing pattern  135  and a protrusion  145 , respectively (see FIG. 8C).  
         [0069]    The first roller  370  is rolled along a surface of the first resin layer  130  so as to form the light diffusing pattern  135  on the first resin layer  130  and the second roller  380  is rolled along a surface of the second resin layer  140  so as to form the protrusion  145  on the second resin layer  140 , respectively. The light diffusing pattern  135  and the protrusion  145  may be formed by transferring the base body  110  to be passed between the first and second rollers  370  and  380 .  
         [0070]    After the light diffusing pattern  135  and the protrusion  145  are formed on the first and second resin layers  130  and  140 , respectively, the first resin layer  130  and the second resin layer  140  are exposed to the ultraviolet rays, so the first resin layer  130  on which the light diffusing pattern  135  is formed and the second resin layer  140  on which the protrusion  145  is formed are cured.  
         [0071]    Hereinafter, a method of fabricating a roller according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.  
         [0072]    [0072]FIGS. 9A to  9 E are views for illustrating a method of manufacturing a roller according to an exemplary embodiment of the present invention.  
         [0073]    Referring to FIG. 9A, a first photoresist layer  310  is coated on a first substrate  300  by using a spin coating method.  
         [0074]    Then, a pattern mask  330  is aligned with the first photoresist layer  310 . The pattern mask  330  includes a chrome layer  332  that is partially opened corresponding to positions on which a light diffusing pattern (not shown) is formed. A light  335  is provided to the pattern mask  330  aligned with the first photoresist layer  310 .  
         [0075]    The light  335  provided to the pattern mask  330  is supplied to the first photoresist layer  310  passing through the opening portion  334  of the chrome layer  332  so as to partially expose the first photoresist layer  310 .  
         [0076]    Referring to FIG. 9B, partially exposed portions of the first photoresist layer  310  by the light  335  supplied through the pattern mask  330  is removed through a developing process, thereby forming a second photoresist layer  317  on which a first pattern  315  having size identical to and shape that is reversed with respect to that of the light diffusing pattern  135  is formed.  
         [0077]    Referring to FIG. 9C, a metal layer  340  is formed on the second photoresist layer  317  by using a sputtering method, on which the first pattern  315  is formed. The metal layer  340  has a second pattern  345  having size and shape identical to those of the light diffusing pattern  135  by means of the first pattern  315  of the second photoresist layer  317 .  
         [0078]    The second photoresist layer  317  formed under the metal layer  340  is removed through an ashing process and the metal layer  340  is separated from the second photoresist layer  317 .  
         [0079]    The separated metal layer  340  is attached on a second substrate  350  as shown in FIG. 9D and a synthetic resin layer  360  is coated over the second pattern  345  of the metal layer  340 . In this exemplary embodiment, the synthetic resin layer  360  is preferably coated over the second pattern  345  without a void space between the synthetic resin layer  360  and the second pattern  345  of the metal layer  340 .  
         [0080]    By coating the synthetic resin layer  360  over the second pattern  345  of the metal layer  340 , a third pattern  365  is formed on the synthetic resin layer  360 . The third pattern  365  has a reversed shape with respect to the light diffusing pattern  135  and is named as a transfer pattern hereinafter.  
         [0081]    Referring to FIG. 9E, the synthetic resin layer  360 , on which the transfer pattern  365  is formed, is attached along an outer surface of the first roller  370 . The light diffusing pattern  135  of the first resin layer  130  according to the exemplary embodiment of the present invention is formed by using the first roller  370  having the transfer pattern  365 .  
         [0082]    [0082]FIG. 10 is a schematic view showing an LCD apparatus according to an exemplary embodiment of the present invention.  
         [0083]    Referring to FIG. 10, an LCD apparatus  700  includes a light supply module  500 , a light adjusting module  400  and a display module  600 .  
         [0084]    The light supply module  500  includes at least one CCFL (Cold Cathode Fluorescent Lamp) so as to emit the first light  510  needed to display the image. The first light  510  emitted from the light supply module  500  is supplied to the light adjusting module  400 .  
         [0085]    The light adjusting module  400  includes at least two optical members  100  and  200 .  
         [0086]    In this exemplary embodiment, the light adjusting module  400  includes a diffusing sheet  100  and a prism sheet  200 . The diffusing sheet  100  changes a brightness distribution of the first light  510  so as to emit the second light  420  having a uniform brightness distribution. The prism sheet  200  receives the second light  420  provided from the diffusing sheet  100  and changes directions of the second light  420  so as to emit a third light  430 . The diffusing sheet  100  has a same structure as the optical sheet (see FIG. 4) and is fabricated through a same process as the optical sheet (see FIGS. 7A to  7 D), so a method of fabricating the diffusing sheet  100  will be omitted in detail.  
         [0087]    The display module  600  receives the third light  430  provided from the prism sheet  200  and emits an image light  610  having image information.  
         [0088]    In this exemplary embodiment, the display module  600  is an LCD panel that displays the image information using a liquid crystal. The LCD panel may have various shapes so as to display the image information using the liquid crystal.  
         [0089]    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.