Abstract:
The present invention relates to a light guide plate, and a method and apparatus of manufacturing the same. The light guide plate includes; a transparent substrate including an active area and a dummy area defined in the periphery of the active area, wherein a groove for coupling other members is defined in the dummy area; and a pattern layer disposed on one surface of the substrate. The pattern layer is not disposed on the dummy area of the substrate, but disposed on the active area of the substrate. Since the pattern layer is formed on only the active are of the substrate using a spinless process, a material for forming the pattern layer may not be wasted to reduce material costs. Also, since a plurality of grooves are formed in the substrate before the pattern layer is formed on the substrate, conventional limitations, whereby it is difficult to perform a groove forming process due to a pattern layer cured by forming a plurality of grooves after the pattern layer is formed, may be overcome.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a light guide plate capable of being applied to a backlight of a liquid crystal display (LCD) device. 
       Background Art 
       [0002]    Generally, liquid crystal display (LCD) device does not have a light source in itself. Thus, a backlight unit functioning as a light source is mounted on the rear of a liquid crystal panel. The backlight unit functioning as the light source of the LCD device may be largely classified into a direct type and an edge type. 
         [0003]    In case of the direct type, a light source is arranged on an entire lower surface of the liquid crystal panel, whereby light emitted from the light source is directly transmitted to the liquid crystal panel. Meanwhile, in case of the edge type, a light source is arranged at one lower side of the liquid crystal panel, whereby light emitted from the light source is transmitted to the liquid crystal panel through the use of light guide plate. 
         [0004]    Hereinafter, an edge type LCD device according to the related art will be described with reference to the accompanying drawings. 
         [0005]      FIG. 1  is a cross sectional view of an LCD device according to the related art, and  FIGS. 2   a  and  2   b  are plane view and cross sectional view of a light guide plate according to the related art. 
         [0006]    As shown in  FIG. 1 , the LCD device according to the related art includes a liquid crystal panel  1  and a backlight unit  2 . 
         [0007]    The liquid crystal panel  1  is formed in such a way that a liquid crystal layer is provided between lower and upper substrates. 
         [0008]    The backlight unit  2  is positioned below the liquid crystal panel  1 , and the backlight unit  2  emits light to the liquid crystal panel  1 . 
         [0009]    The backlight unit  2  includes a light guide plate  10 , a light source  20 , optical sheets  30 , and a reflection plate  40 . 
         [0010]    The light guide plate  10  guides the light emitted from the light source  20  toward the liquid crystal panel  1 . 
         [0011]    The light source  20  is positioned at a lateral side of the light guide plate  10 , and the light source  20  emits light to the lateral side of the light guide plate  10 . 
         [0012]    The optical sheets  30  uniformly transmit the light passing through the light guide plate  10  to the liquid crystal panel  1 , wherein the optical sheets  30  are formed by combining a plurality of sheets such as diffusion sheet and prism sheet. 
         [0013]    The reflection plate  40  is positioned below the light guide plate  10 , to thereby prevent a loss of light emitted from the light source. 
         [0014]    As shown in  FIGS. 2   a  and  2   b , the light guide plate  10  according to the related art comprises a predetermined pattern layer  14  on a substrate  12  so as to change a path of light. 
         [0015]    At the edges of the light guide plate  40 , there are a plurality of grooves  15  to be combined with other members. That is, the light guide plate  10  is combined with other members through the grooves  15 , to thereby complete the backlight unit. 
         [0016]    The light guide plate  10  according to the related art may be manufactured by steps of coating a predetermined material on the entire surface of the substrate  12  through a spin coating method; forming the pattern layer  14  through the use of predetermined mold; and forming the grooves  15  by removing predetermined portions at the side. 
         [0017]    However, in case of the light guide plate  10  according to the related art, the grooves  15  are formed after forming the pattern layer  15  on the substrate  12 . For forming the grooves  15 , the pattern layer  14  is removed together with the substrate  12 . However, since hardness of the pattern layer  14  becomes strong after completing the curing process, it is difficult to carry out the process of forming the grooves  15 , which might cause the increase of defect. 
         [0018]    In the light guide plate  10  according to the related art, since the predetermined material is coated on the entire surface of the substrate  12  through the spin coating method, the pattern layer  14  is coated on the entire surface of the substrate  12 . However, light travel is interrupted in the edges of the light guide plate  10  because the grooves  15  of the edge of the light guide plate  10  are combined with other members. That is, if the material is coated on the entire surface of the substrate  12 , the material is wasted. Also, a large amount of material is wasted during the spin coating process, which causes the increase of material cost. 
       DISCLOSURE 
     Technical Problem 
       [0019]    Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a light guide plate which overcomes a problem of defects during a process of forming grooves, and reduces a material cost by preventing a material from being wasted. 
       Technical Solution 
       [0020]    To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a light guide plate comprising: a transparent substrate including active and dummy areas, wherein the dummy area is positioned in the circumference of the active area, and the dummy area is provided with a plurality of grooves to be combined with other members; and a pattern layer on one surface of the substrate, wherein the pattern layer is formed in the active area of the substrate, and is not formed in the dummy area of the substrate. 
         [0021]    Also, the substrate and pattern layer are formed of poly methyl methacrylate (PMMA), and an adhesive is not provided between the substrate and pattern layer. 
         [0022]    Furthermore, bead structure are additionally included in the pattern layer. 
         [0023]    Also, a pattern layer is additionally formed on the other surface of the substrate, and the pattern layer on the other surface of the substrate is not formed in the dummy area, and is formed in the active area. 
         [0024]    In another aspect of the present invention, there is provided a method of manufacturing a light guide plate with a pattern layer on an active area of a substrate comprising: preparing the substrate with a plurality of grooves in a dummy area in the circumference of the active area; coating the active area of the substrate with a pattern material by a spinless coating method; curing edges of the pattern material coated; forming a pattern in the pattern material by bring a predetermined mold into contact with the pattern material; curing the pattern material while being brought into contact with the mold; and separating the mold. 
         [0025]    In addition, the method further comprises carrying out IR (infrared ray) or UV (ultraviolet ray) drying process and cooling process after coating the pattern material. 
         [0026]    The process of coating the pattern material comprises coating the pattern material including bead structures therein. 
         [0027]    Also, the processes of forming the pattern in the pattern material, curing the pattern material, and separating the mold are consecutively carried out by an apparatus including a pair of first rolls consisting of a first upper roll and a first lower roll, a pair of second rolls consisting of a second upper roll and a second lower roll, a mold wound on the first upper roll and the second upper roll, and a UV irradiation apparatus positioned between the first upper roll and the second upper roll. 
         [0028]    In another aspect of the present invention, there is provided an apparatus of manufacturing a light guide plate comprising: a pair of first roll consisting of a first upper roll and a first lower roll; a pair of second roll consisting of a second upper roll and a second lower roll; a third roll positioned in the rear upper side of the second upper roll; a fourth roll positioned in the upper side between the first upper roll and the second upper roll; a mold rotated while being wound among the first upper roll, the second upper roll, the third roll and the fourth roll; and a UV irradiation apparatus positioned between the first upper roll and the second upper roll. 
       Advantageous Effects 
       [0029]    According to the present invention, a material for forming the pattern layer is not wasted because the pattern layer is formed only in the active area of the substrate through a spinless coating process. Also, a plurality of grooves are formed before forming the pattern layer on the substrate, so that it is possible to overcome a related art problem of defects, wherein the defects are caused by difficulties in forming the grooves when the plurality of grooves are formed in the cured pattern layer after curing the pattern layer. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0030]      FIG. 1  is a cross sectional view of an LCD device according to the related art. 
           [0031]      FIGS. 2   a  and  2   b  are plane view and cross sectional view of a light guide plate according to the related art. 
           [0032]      FIG. 3   a  is a plane view of a light guide plate according to one embodiment of the present invention, and  FIG. 3   b  is a cross sectional view of a light guide plate according to one embodiment of the present invention. 
           [0033]      FIG. 4  is a cross sectional view of a light guide plate according to another embodiment of the present invention. 
           [0034]      FIG. 5  is a cross sectional view of a light guide plate according to another embodiment of the present invention. 
           [0035]      FIGS. 6   a  to  6   f  are cross sectional views of a method of manufacturing a light guide plate according to one embodiment of the present invention. 
           [0036]      FIG. 7  is a rough view of an apparatus of manufacturing a light guide plate according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
         [0038]      FIG. 3   a  is a plane view of a light guide plate according to one embodiment of the present invention, and  FIG. 3   b  is a cross sectional view of a light guide plate according to one embodiment of the present invention. 
         [0039]    As shown in  FIGS. 3   a  and  3   b , a light guide plate according to one embodiment of the present invention includes a substrate  100  and a pattern layer  200 . 
         [0040]    The substrate  100  is formed of a transparent material, for example, poly methyl methacrylate (PMMA). Owing to great transmittance of PMMA, PMMA is appropriate for a material of light guide plate. However, the material of substrate  100  is not limited to PMMA. 
         [0041]    The substrate  100  is a base of the light guide plate, wherein the substrate  100  includes an active area and a dummy area. In the active area positioned in the center of the substrate  100 , light travels toward a liquid crystal panel. In the dummy area positioned in the circumference of the substrate  100 , light doesn&#39;t travel toward the light crystal panel. The dummy area corresponds to a peripheral region of the active area. 
         [0042]    The dummy area of the substrate  100  is provided with a plurality of grooves  110 . By the use of grooves  100 , the light guide plate may be combined with other members of a backlight unit. 
         [0043]    The pattern layer  200  is formed on a surface of the substrate  100 . Especially, the pattern layer  200  is formed in the active area of the substrate  100 , and is not formed in the dummy area of the substrate  100 . 
         [0044]    Through a spinless coating process instead of a spin coating process, the pattern layer  200  is formed in the active area of the substrate  100 . According to the present invention, it is possible to prevent a material for forming the pattern layer  200  from being wasted, to thereby reduce a material cost. 
         [0045]    The pattern layer  200  may have an uneven surface structure, wherein a cross sectional shape of the uneven surface structure may vary, for example, triangular cross section, circular cross section, elliptical cross section, and etc. On the plane view, the uneven surface with the above cross section may be a stripe pattern, matrix pattern, or dot pattern. 
         [0046]    By applying the various shapes of pattern layer  200 , it is possible to reduce the number of optical sheets to be used, or not to use the optical sheets such as prism sheets. 
         [0047]    The pattern layer  200  may be formed of poly methyl poly methyl methacrylate (PMMA). In this case, poly methyl methacrylate (PMMA) may be obtained by curing methyl methacrylate (MMA). Thus, without using an additional adhesive, the pattern layer  200  of poly methyl methacrylate (PMMA) may be formed on the substrate  100 . That is, it is possible that the adhesive is not provided between the substrate  100  and the pattern layer  200 . This will be easily understood with reference to the following processes. 
         [0048]      FIG. 4  is a cross sectional view of a light guide plate according to another embodiment of the present invention. Except that bead structures  300  are included in a pattern layer  200 , the light guide plate of  FIG. 4  is identical in structure to the light guide plate of  FIGS. 3   a  and  3   b . Thus, wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and a detailed explanation for the same parts will be omitted. 
         [0049]    As shown in  FIG. 4 , the light guide plate according to another embodiment of the present invention includes a substrate  100 , the pattern layer  200  on an active area of the substrate  100 , and the bead structures  300  included in the pattern layer  200 . 
         [0050]    The bead structures  300  are provided to enhance light efficiency by diffusing light. If additionally providing the bead structures  300 , it is possible to enhance the light efficiency of light guide plate. 
         [0051]    The bead structures  300  may be formed of oxide, for example, SnO 2 , TiO 2 , ZnO 2 , SiO 2 , CeO 2 , and etc. 
         [0052]      FIG. 5  is a cross sectional view of a light guide plate according to another embodiment of the present invention. Except that pattern layers  210  and  220  are formed on both surfaces of a substrate  100 , the light guide plate of  FIG. 5  is identical in structure to the light guide plate of  FIGS. 3   a  and  3   b . Thus, wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and a detailed explanation for the same parts will be omitted. 
         [0053]    As shown in  FIG. 5 , the light guide plate according to another embodiment of the present invention includes the substrate  100 , the first pattern layer  210  on an active area of one surface of the substrate  100 , and the second pattern layer  220  on an active area of the other surface of the substrate  100 . 
         [0054]    A detailed structure of each of the first and second pattern layers  210  and  220  is the same as that of the pattern layer  200  shown in  FIGS. 3   a  and  3   b.    
         [0055]    Meanwhile, bead structures may be included in at least any one of the first and second pattern layers  210  and  220 . 
         [0056]      FIGS. 6   a  to  6   f  are cross sectional views of a method of manufacturing the light guide plate according to one embodiment of the present invention, in particular, the light guide plate according to  FIGS. 3   a  and  3   b.    
         [0057]    First, as shown in  FIG. 6   a , the substrate  100  is prepared. 
         [0058]    The substrate  100  may be formed of poly methyl methacrylate (PMMA), but not necessarily. 
         [0059]    A process of preparing the substrate  100  includes a step of forming the plurality of grooves in the dummy area corresponding to the peripheral region of the active area of the substrate  100 . The step of forming the plurality of grooves may be carried in various methods generally known to those in the art. 
         [0060]    Before forming the pattern layer on the substrate  100 , the plurality of grooves are formed in the substrate  100 . Thus, it is possible to overcome a related art problem related with difficulty in the step of forming the plurality of grooves, wherein the related art problem occurs when the pattern layer is cured and then the plurality of grooves are formed in the cured pattern layer. 
         [0061]    If needed, it is possible to manufacture the substrate  100  with the plurality of grooves in the manufacturing process, instead of forming the plurality of grooves in the manufactured substrate  100  after manufacturing the substrate  100 . 
         [0062]    As shown in  FIG. 6   b , a pattern material  200   a  is coated on the active area of the substrate  100 . 
         [0063]    The pattern material  200   a  may be formed of methyl methacrylate (MMA). Because methyl methacrylate (MMA) is a low molecule of liquid state, methyl methacrylate (MMA) may be coated on the active area of the substrate  100  by the spinless coating process using a printing nozzle  400 . 
         [0064]    For the spinless coating process, the printing nozzle  400  is moved while the substrate  100  is fixed, or the substrate  100  is moved while the printing nozzle  400  is fixed. 
         [0065]    If needed, an additive such as polymerization initiator or curing agent may be added into methyl methacrylate (MMA), and then methyl methacrylate (MMA) with the additive therein may be coated. 
         [0066]    Although not shown, after coating the pattern material  200   a , IR (infrared ray) or UV (ultraviolet ray) drying process may be carried out so as to make the coated pattern material  200   a  be a gel state. Also, a cooling process may be carried out after the IR or UV drying process, to thereby restore the substrate  100  expanded during the drying process. 
         [0067]    Then, as shown in  FIG. 6   c , edges of the coated pattern material  200   a  are cured. 
         [0068]    Generally, the pattern material  200   a  is coated in a quadrangle shape on the active area of the substrate  100 . Thus, four edges of the quadrangle-shaped pattern material  200   a  are cured. 
         [0069]    The reason why the edges of the pattern material  200   a  are cured before the process of forming the pattern in the pattern material  200   a  (See the following process of  FIG. 6   d ) is to prevent the shape of pattern material  200   a  from being deformed when a mold is brought into contact with the pattern material  200   a  for the process of forming the pattern. 
         [0070]    Thus, the edge of the pattern material  200   a  to be cured has such a width as to prevent the deformation of pattern material  200   a  even though the mold is brought into contact with the pattern material  200   a  for the process of forming the pattern. 
         [0071]    The process of curing the edges of the pattern material  200   a  may be carried out by a UV irradiation apparatus. 
         [0072]    Then, as shown in  FIG. 6   d , the predetermined mold  500  is brought into contact with the pattern material  200   a , to thereby form the pattern in the pattern material  200   a.    
         [0073]    The mold  500  is formed in consideration to the shape of pattern layer needed to be obtained. For example, a cross section of the mold  500  may be variously changed into a triangle, circle, or ellipse; and a pattern with the cross section may be variously changed into a stripe pattern, matrix pattern, or dot pattern. 
         [0074]    As shown in  FIG. 6   e , the pattern material  200   a  with the pattern is cured. 
         [0075]    The process of curing the pattern material  200   a  may be carried out through the use of UV irradiation apparatus. 
         [0076]    As shown in the drawings, the process of curing the pattern material  200   a  is carried out under the circumstances the mold  500  is brought into contact with the pattern material  200   a . Especially, in order to cure the pattern material  200   a  by UV irradiation over the mold  500 , the mold  500  is formed of a transparent material. 
         [0077]    As shown in  FIG. 6   f , the mold  500  is separated, to thereby complete the light guide plate of  FIGS. 3   a  and  3   b , which is provided with the pattern layer  200  on the active area of the substrate  100 . 
         [0078]    In the above process of  FIG. 6   b , the bead structures of the oxide such as SnO 2 , TiO 2 , ZnO 2 , SiO 2  or CeO 2  are included in the pattern material  200   a , and then the pattern material  200   a  is coated, to thereby obtain the light guide plate of  FIG. 4 . 
         [0079]    When the above process is applied to both surfaces of the substrate  100 , it is possible to obtain the light guide plate of  FIG. 5 . 
         [0080]    The processes of  FIGS. 6   d  to  6   f  among the aforementioned processes may be consecutively carried out in an apparatus without pause, which will be explained as follows. 
         [0081]      FIG. 7  is a rough view of an apparatus of manufacturing the light guide plate according to one embodiment of the present invention. This apparatus may perform the consecutive processes of forming the pattern in the pattern material through the use of mold (process of  FIG. 6   d ), curing the pattern material with the pattern (process of  FIG. 6   e ), and separating the mold (process of  FIG. 6   f ). 
         [0082]    As shown in  FIG. 7 , the apparatus of manufacturing the light guide plate according to one embodiment of the present invention includes a pair of first rolls  611  and  612 , a pair of second rolls  621  and  622 , a third roll  630 , a fourth roll  640 , a mold  500 , a belt  700 , and a UV irradiation apparatus  800 . 
         [0083]    The pair of first rolls  611  and  612  comprises the first upper roll  611  and first lower roll  612 . The substrate  100  coated with the pattern material  200   a  is introduced into a space between the first upper roll  611  and the first lower roll  612 . 
         [0084]    The pair of second rolls  621  and  622  comprises the second upper roll  621  and second lower roll  622 . The light guide plate with the pattern layer  200  on the substrate  100  is taken out of a space between the second upper roll  621  and the second lower roll  622 . 
         [0085]    The third roll  630  is positioned in the rear upper side of the second upper roll  621 , wherein the third roll  630  separates mold  500  from the pattern material  200   a.    
         [0086]    The fourth roll  640  is positioned in the upper side between the first and second upper rolls  611  and  621 , wherein the fourth roll  640  makes it possible to maintain a tension of the mold  500 . 
         [0087]    The mold  500  is rotated while being wound among the first upper roll  611 , second upper roll  621 , third roll  630 , and fourth roll  640 , whereby the mold  500  is brought into contact with the pattern material  200   a  coated on the substrate  100 , thereby forming the pattern layer  200 . 
         [0088]    The belt  700  is wound on the first lower roll  612  and second lower roll  622 , whereby the substrate  100  is moved through the use of belt  700 . It is possible to provide an additional roll for winding the belt  700  on the first lower roll  612  and second lower roll  622 . 
         [0089]    The UV irradiation apparatus  800  is positioned between the first upper roll  611  and second upper roll  621 , to thereby cure the pattern material  200   a  with the pattern on the substrate  100  being moved. 
         [0090]    An operation of the apparatus shown in  FIG. 7  will be explained as follows. 
         [0091]    First, the substrate  100  coated with the pattern material  200   a  is introduced into the space between the pair of first rolls, that is, first upper roll  611  and first lower roll  612 . Then, the mold  500  rotated while being wound among the first upper roll  611 , second upper roll  621 , third roll  630  and fourth roll  640  is brought into contact with the pattern material  200   a , thereby forming the pattern in the pattern material  200   a.    
         [0092]    Under the circumstances the mold  500  is brought into contact with the pattern material  200   a , the substrate  100  is moved toward the pair of second rolls  621  and  622 . The substrate  100  is moved by rotation of the belt  700 . 
         [0093]    During movement of the substrate  100 , the pattern material  200   a  is cured by the UV irradiation apparatus  800 . 
         [0094]    Then, after curing the pattern material  200   a , the substrate  100  is taken out of the space between the pair of second rolls  621  and  622 , that is, second upper roll  621  and the second lower roll  622 . While the substrate  100  is taken out of the space, the mold  500  being brought into contact with the pattern material  200   a  is wound on the third roll  630 , simultaneously. Naturally, the contact between the mold  500  and the pattern material  200   a  is released so that the mold  500  is separated from the substrate  200 . 
         [0095]    Meanwhile, the above apparatus of manufacturing the light guide plate according to the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. For example, a roll with the mold  500  wound thereon may be additionally provided, and a roll for moving the substrate  100  may be additionally provided. Also, the apparatus of manufacturing the light guide plate according to the present invention may be simplified in structure by omitting at least one of the third roll  630  and fourth roll  640 . 
         [0096]      FIG. 7  illustrates the apparatus of consecutively carrying out the processes of  FIGS. 6   d  to  6   f . The apparatus of carrying out the processes of  FIGS. 6   a  to  6   c  is arranged in-line before the apparatus of  FIG. 7 , to thereby consecutively carry out the entire processes for manufacturing the light guide plate according to the present invention.