Abstract:
A liquid crystal display (LCD) module includes a liquid crystal panel; a backlight unit supplying light to the liquid crystal panel; a PCB including a plurality of output pads connected to the liquid crystal panel and a plurality of dummy output pads; and a cover shield protecting the PCB and including an embossing pattern, wherein at least one of the plurality of dummy output pads facing the embossing pattern is electrically isolated.

Description:
[0001]    The present invention claims the benefit of Korean Patent Application No. 2006-0131738, filed in Korea on Dec. 21, 2006, which is hereby incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The present application relates to a liquid crystal display module, and in particular, to a liquid crystal display (LCD) module and a method of fabricating the same. 
       BACKGROUND 
       [0003]    Display devices have typically used cathode-ray tubes (CRT). Presently, much effort has been made to study and develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDP), field emission displays, and electro-luminescence displays (ELD), as a substitute for CRT. LCD devices have advantages over the other flat panel displays, some of the advantages are high resolution, light weight, thin profile, compact size, and low power supply requirements. 
         [0004]    In general, an LCD device includes two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other. A voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field, thereby changing the light transmissivity of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field. 
         [0005]    Because the LCD device is a non-emissive type display device, a backlight is needed to supply the non-emissive type display device with light. 
         [0006]      FIG. 1  is an exploded perspective view illustrating an LCD module according to the related art, and  FIG. 2  is a cross-sectional view illustrating the LCD module of  FIG. 1 . 
         [0007]    Referring to  FIGS. 1 and 2 , an LCD module  1  includes a liquid crystal panel  30 , a backlight unit  20 , a main supporter  10 , a bottom cover  40  and a top cover  50 . 
         [0008]    The backlight unit  20  and the liquid crystal panel  30  are sequentially located over a bottom cover  40 . The main supporter  10  has a rectangular frame shape and supports the backlight unit  20  and the liquid crystal panel  30 . The main supporter  10  is combined with the bottom cover  40 . The top cover  50  is disposed on the top of the LCD module  1 . The top cover  50  presses and fixes a peripheral portion of the liquid crystal panel  30  and is combined with the main supporter  10  and the bottom cover  40 . 
         [0009]    A printed circuit board (PCB)  34  as a driving circuit of the liquid crystal panel  30  is connected to the liquid crystal panel  30  through a plurality of tape carrier package (TCP) films  32  which are flexible. The PCB  34  has a plurality of output pads and dummy output pads  35  in a pad portion PA. The TCP film  32  has a plurality of input pads and output pads. The liquid crystal panel  30  has a plurality of input pads. The output pad of the PCB  34  is connected to the input pad of the TCP film  32 , and the output pad of the TCP film  32  is connected to the input pad of the liquid crystal panel  30 . The dummy pads  35  are located between the output pads of the PCB  34 . 
         [0010]    To connect the output pad of the PCB  34  to the input pad of the TCP film  32 , an anisotropic conductive film (ACF) is used. The ACF includes a bonding material and a plurality of conductive particles in the bonding material. The ACF is formed entirely in the pad portion PA. To improve bonding efficiency between the PCB  34  and the TCP film  32 , the same output pad structure in the PCB  34  is formed, and to do this, the dummy output pads  35  are formed. 
         [0011]    The backlight unit  20  includes a backlight  24 , a reflecting sheet  22 , a light guide plate  26 , and optical sheets  28  such as a prism sheet and a diffusion sheet. A lamp  24  is used as the backlight  24 , and the lamp  24  is located at a side portion of the LCD module  1 . The lamp  24  is guided by a lamp guider (not shown) that partially covers the lamp  24 . The lamp  24  is fixed by a couple of lamp holders that are located at both ends of the lamp  24 . 
         [0012]    A cover shield  60  is located below the bottom cover  40  and covers the PCB  34  and a lamp driving circuit. 
         [0013]    Referring to  FIG. 2 , when modulizing the LCD module  1 , for space efficiency, the PCB  34  is located below the bottom cover  40 . To connect the PCB  34  at a bottom portion and the liquid crystal panel  40  at a top portion, the TCP film  32  is bent, for example, twice. The cover shield  60  has an embossing pattern  63  at an inner surface of the cover shield  60 . The embossing pattern  63  faces and is spaced apart from the PCB  34 . 
         [0014]      FIG. 3  is a view illustrating relationship of dummy output pads of a PCB and embossing patterns of a cover shield according to the related art, and  FIGS. 4A and 4B  are cross-sectional views, taken along a line IV-TV, illustrating states that an external pressure is not applied to a cover shield and applied to the cover shield, respectively. 
         [0015]    Referring to  FIG. 3 , embossing patterns  63  correspond to a pad portion PA at a periphery of a PCB  34 . Most of the embossing patterns  63  correspond to dummy output pads  35 . An ACF  70  is formed entirely on the pad portion PA. A first portion of the ACF  70  connects an output pad  36  of the PCB  34  to an input pad of the TCP  32 . A second portion of the ACF  70  located on the dummy pads  35  is exposed. 
         [0016]    The output pads  36  and the dummy output pads  35  of the PCB  34  are connected to a PCB ground portion (not shown) to ground them. For example, all the pads  36  and  35  are connected to a ground line in the PCB  34  to ground them. To strengthen ground, the PCB ground portion is connected to at least one of other components of the LCD module made of metal which can act as other ground portion. For example, at least one or combination of a bottom cover ( 40  of  FIGS. 1 and 2 ), a top cover ( 50  of  FIGS. 1 and 2 ), a cover shield  60  and so on can be used as the other ground portion. To prevent electromagnetic interference (EMI), resistance, for example, of several ohms between the PCB ground portion and the other ground portion is needed. To do this, a resistor chip having several ohms may be used between the PCB ground portion and the other ground portion, and thus a predetermined ground state preventing EMI is obtained. 
         [0017]    Referring to  FIG. 4A , when an external pressure is not applied to the cover shield, a distance between the embossing pattern  63  and the second portion of the ACF  70  remains. 
         [0018]    Referring to  FIG. 4B , when an external pressure is applied to the cover shield, the embossing pattern  63  moves downward and presses the ACE  70 . Accordingly, the embossing pattern  63  is electrically connected to the dummy output pad  35  through conductive particles  72  of the ACF  70 . Due to such the unexpected connection, resistance between the PCB ground portion and the cover shield usable as the other ground portion is about 0 ohm, and thus the predetermined ground state in the PCB changes. Accordingly, there may occur EMI, and display quality is reduced. 
       SUMMARY 
       [0019]    Accordingly, the present invention is directed to a liquid crystal display (LCD) module that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
         [0020]    An advantage of the present invention is to provide a liquid crystal display (LCD) module that can improve display quality. 
         [0021]    Additional features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. These and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0022]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a liquid crystal display (LCD) module includes a liquid crystal panel; a backlight unit supplying light to the liquid crystal panel; a PCB including a plurality of output pads connected to the liquid crystal panel and a plurality of dummy output pads; and a cover shield protecting the PCB and including an embossing pattern, wherein at least one of the plurality of dummy output pads facing the embossing pattern is electrically isolated. 
         [0023]    In another aspect, a liquid crystal display (LCD) module includes a liquid crystal panel; a backlight unit supplying light to the liquid crystal panel; a PCB including a plurality of output pads connected to the liquid crystal panel and a plurality of dummy output pads, the plurality of output pads and the plurality of dummy output pads connected to a ground portion; and a cover shield protecting the PCB and including an embossing pattern, wherein at least one of the plurality of dummy output pads facing the embossing pattern has an isolated piece which corresponds to the embossing pattern. 
         [0024]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide farther explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
           [0026]    In the drawings: 
           [0027]      FIG. 1  is an exploded perspective view illustrating an LCD module according to the related art; 
           [0028]      FIG. 2  is a cross-sectional view illustrating the LCD module of  FIG. 1 ; 
           [0029]      FIG. 3  is a view illustrating relationship of dummy output pads of a PCB and embossing patterns of a cover shield according to the related art; 
           [0030]      FIGS. 4A and 4B  are cross-sectional views, taken along a line IV-IV, illustrating states that an external pressure is not applied to a cover shield and applied to the cover shield, respectively; 
           [0031]      FIG. 5  is an exploded perspective view illustrating an LCD module according to an embodiment of the present invention; 
           [0032]      FIG. 6  is a view illustrating relationship of dummy output pads of a PCB having isolation region and embossing patterns of a cover shield according to the embodiment; and 
           [0033]      FIGS. 7 and 8  are cross-sectional views taken along lines VII-VII and VIII-VIII, respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    Reference will now be made in detail to illustrated embodiments of the present invention, which are illustrated in the accompanying drawings. 
         [0035]      FIG. 5  is an exploded perspective view illustrating an LCD module according to an embodiment of the present invention. 
         [0036]    Referring to  FIG. 5 , an LCD module  101  includes a liquid crystal panel  130 , a backlight unit  120 , a main supporter  110 , a bottom cover  140  and a top cover  150 . 
         [0037]    The backlight unit  120  and the liquid crystal panel  130  are sequentially located over a bottom cover  140 . The main supporter  110  has a rectangular flame shape and supports the backlight unit  120  and the liquid crystal panel  130 . The main supporter  110  is combined with the bottom cover  140 . The top cover  150  is disposed on the top of the liquid crystal panel. The top cover  150  presses and fixes a peripheral portion of the liquid crystal panel  130  and is combined with the main supporter  110  and the bottom cover  140 . 
         [0038]    A PCB  134  as a driving circuit of the liquid crystal panel  130  is connected to the liquid crystal panel  130  through a plurality of TCP films  132  which are flexible. The PCB  134  has a plurality of output pads and dummy output pads  135  in a pad portion PA. The output pads of the PCB  134  are located in a first region of the pad portion PA, and the dummy output pads of the PCB  134  are located in a second region of the pad portion PA. 
         [0039]    The TCP film  132  has a plurality of input pads and output pads. The liquid crystal panel  130  has a plurality of input pads. The output pad of the PCB  134  is connected to the input pad of the TCP film  132 , and the output pad of the TCP film  132  is connected to the input pad of the liquid crystal panel  130 . The dummy pads  135  are located between the output pads of the PCB  134 . 
         [0040]    To connect the output pad of the PCB  134  to the input pad of the TCP film  132 , an anisotropic conductive film (ACF) is used. The ACF includes a bonding material and a plurality of conductive particles in the bonding material. The ACF is formed entirely in tie pad portion PA To improve bonding efficiency between the PCB  134  and the TCP film  132 , the same output pad structure in the PCB  134  is formed, and to do this, the dummy output pads  135  are formed. 
         [0041]    The backlight unit  120  includes a backlight  124 , a reflecting sheet  122 , a light guide plate  126 , and optical sheets  128  such as a prism sheet and a diffusion sheet. A lamp  124  is used as the backlight  124 , and the lamp  124  is located at a side portion of the LCD module  101 . The lamp  124  is guided by a lamp guider (not shown) that partially covers the lamp  124 . The lamp  124  is fixed by a couple of lamp holders that are located at both ends of the lamp  124 . 
         [0042]    A cover shield  160  is located below the bottom cover  140  and covers the PCB  134  and a lamp driving circuit to protect them. 
         [0043]    When modulizing the LCD module  101 , for space efficiency, the PCB  134  is located below the bottom cover  140 . To connect the PCB  134  at a bottom portion and the liquid crystal panel  140  at a top portion, the TCP film  132  is bent, for example, twice. The cover shield  160  has an embossing pattern  163  at an inner surface of the cover shield  160 . The embossing pattern  163  faces and is spaced apart from the PCB  134 . 
         [0044]    The second region of the pad portion PA has an isolation region IA where the dummy output pads  135  are not connected to lines of the PCB and a PCB ground. Accordingly, the dummy output pads  135  in the isolation region IA are electrically floated. 
         [0045]      FIG. 6  is a view illustrating relationship of dummy output pads of a PCB having isolation region and embossing patterns of a cover shield according to the embodiment, and  FIGS. 7 and 8  are cross-sectional views taken along lines VII-VII and VIII-VIII, respectively. 
         [0046]    Referring to  FIGS. 6 to 8 , embossing patterns  163  correspond to a pad portion PA at a periphery of a PCB  134 . Most of the embossing patterns  163  correspond to dummy output pads  135 . An ACF  170  is formed entirely on the pad portion PA. A first portion of the ACF  170  connects an output pad  136  of the PCB  134  to an input pad of the TCP  132 . A second portion of the ACF  170  located on the dummy pads  135  is not covered by and exposed between the TCP films. 
         [0047]    The output pads  136  and the dummy output pads  135  of the PCB  134  are connected to a PCB ground portion (not shown) to ground them. For example, all the pads  136  and  135  are connected to a ground line in the PCB  134  to ground them. To strengthen ground, the PCB ground portion is connected to at least one of other components of the LCD module made of metal which can act as other ground portion. For example, at least one or combination of a bottom cover ( 140  of  FIG. 5 ), a top cover ( 150  of  FIG. 5 ), a cover shield  160  and so on can be used as the other ground portion. To prevent electromagnetic interference (EMI), resistance, for example, of several ohms between the PCB ground portion and the other ground portion is needed. To do this, a resistor chip having several ohms may be used between the PCB ground portion and the other ground portion, and thus a predetermined ground state preventing EMI is obtained. 
         [0048]    An isolation region IA is formed in a second region of the pad portion PA and corresponds to the embossing pattern  163 . The isolation region IA is isolated from other region of the second region of the pad portion PA. For example, the isolation region IA is isolated by a groove H surrounding the isolation region IA. 
         [0049]    The isolation region IA has an area more than a contact area A of the embossing pattern  163  when an external pressure applied. The isolation region IA may have an island shape, for example, rectangular shape, and the groove H may have a frame shape surrounding the isolation region IA. The isolation region IA divides the dummy output pads  135  into first and second pads  135   a  and  135   b  in accordance that the dummy output pads  135  cross the isolation region IA. In other words, the first pad  135   a  does not cross the isolation region IA, while the second pad  135   b  crosses the isolation region IA. The second pad  135   b  may be separated into at least two pieces, for example, three pieces with the groove H between the pieces. Because the piece of the second pad  135   b  in the isolation region IA is electrically disconnected to other lines in the PCB, the piece of the second pad  135   b  in the isolation region IA is electrically disconnected to the PCB ground portion. 
         [0050]    When the embossing pattern  163  is applied with an external pressure and connected to the dummy output pad  135  through the ACF  170 , the embossing pattern  163  is connected to the isolated piece of the second pad  135   b . Accordingly, even when the pressure is applied and the embossing pattern  163  is connected to the dummy output pad  135 , the PCB ground portion is not connected to the cover shield usable as the other ground portion. Accordingly, the predetermined ground state in the PCB  134  does not change. As a result, EMI can be prevented, and display quality can be improved. 
         [0051]    In the above embodiment, the groove is formed to ensure the electrical isolation. To form the groove, process of etching the PCB after forming the output pads and the dummy pads can be applicable. Alternatively, without the groove, the electrical isolation may be obtained. For example, the dummy output pads corresponding to where the groove is formed in the above embodiment may be etched and separated. 
         [0052]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.