Abstract:
The present invention relates to a liquid crystal display and a tablet computer having the same. According to the present invention, there is provided a liquid crystal display, comprising: a liquid crystal display panel for displaying an image; a driving circuit unit connected to the liquid crystal display panel and including a printed circuit board mounted with a circuit component; a top chassis disposed over the liquid crystal display panel; and a fastening member for fastening the printed circuit board of the driving circuit unit to the top chassis.

Description:
[0001]    This application claims the benefit of priority of Korean Patent Application No. 10-2007-0016071 filed on Feb. 15, 2007. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a liquid crystal display and a tablet computer having the same. 
         [0004]    2. Description of the Related Art 
         [0005]    A liquid crystal display (LCD) displays an image on a liquid crystal display panel by controlling the light transmissivity of individual picture elements in response to image signals applied to a plurality of control switches arranged in a matrix form. LCD displays are very widely used because of their superior features such as lightweight, slim structure, low power consumption, full-color, and high resolution. Currently, LCD displays are used in devices such as computers, tablet personal computers, notebook computers, PDAs, portable phones, and television sets. 
         [0006]    As the demand for ultra-thin tablet personal computers has recently increased, several studies have been undertaken in the technology of manufacturing such computers. However, the manufacturing cost of an ultra-thin tablet personal computer increases since the number of processes and necessary components for making a tablet personal computer increases as the computer is made thinner or ultra-thin. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a liquid crystal display, which makes it possible to implement an ultra-thin tablet computer, and a tablet computer having the same. 
         [0008]    According to an aspect of the present invention, there is provided a liquid crystal display, including: a liquid crystal display panel for displaying an image; a driving circuit unit connected to the liquid crystal display panel and including a printed circuit board with a circuit component mounted thereon; a top chassis disposed over the liquid crystal display panel; and a fastening member for fastening the printed circuit board of the driving circuit unit to the top chassis. 
         [0009]    The liquid crystal display may further include a backlight unit for providing light to the liquid crystal display panel; a digitizer for inputting location coordinates; and a mold frame having first and second receiving spaces formed therein, the liquid crystal display panel and the backlight unit being accommodated in the first receiving space, and the digitizer and the printed circuit board being accommodated in the second receiving space. 
         [0010]    The digitizer may be disposed between the mold frame and the printed circuit board. 
         [0011]    The driving circuit unit may further include a flexible printed circuit board for connecting the printed circuit board and the liquid crystal display panel, and the flexible printed circuit board may be bent along a side wall of the mold frame so that the printed circuit board is disposed on the digitizer. 
         [0012]    The fastening member may include a body portion; a first fastening portion formed in the body portion; and a second fastening portion formed in the body portion to be spaced apart from the first fastening portion. 
         [0013]    The top chassis may include a coupling portion, and the printed circuit board includes a base plate on which the circuit component is mounted and a protruding portion formed on a side of the base plate. 
         [0014]    The first fastening portion of the fastening member may be fastened to the protruding portion of the printed circuit board and the second fastening portion may be fastened to the coupling portion of the top chassis. 
         [0015]    The first fastening portion of the fastening member may be formed in the shape of a groove, the second fastening portion may be formed in the shape of a groove or through hole, and the coupling portion of the top chassis may be formed in the shape of a protrusion. 
         [0016]    The coupling portion of the top chassis may be formed in the shape of a protrusion and both ends of the protrusion may be perforated, that is to say, a hole may be formed in each end of the coupling portion protrusion. 
         [0017]    The first fastening portion of the fastening member may be formed in the shape of a groove, the second fastening portion may be formed in the shape of a protrusion, and the coupling portion of the top chassis may be formed in the shape of a through hole. 
         [0018]    The first fastening portion of the fastening member may be formed in the shape of a groove, the second fastening portion may be formed in the shape of a groove or through hole, and the coupling portion of the top chassis may be formed in the shape of a through hole, the liquid crystal display further including a fixing portion to be inserted into the second fastening portion and the coupling portion and to be fixed thereto. 
         [0019]    The body portion of the fastening member may include a first body and a second body bent from the first body, the first fastening portion may be formed in the first body, and the second fastening portion may be formed in the second body. 
         [0020]    The fastening member may be made of a non-conductive elastic material. 
         [0021]    According to another aspect of the present invention, there is provided a tablet computer, including: a liquid crystal display including a liquid crystal display panel for displaying an image, a driving circuit unit connected to the liquid crystal display panel and including a printed circuit board having a circuit component mounted thereon, a top chassis disposed over the liquid crystal display panel, and a fastening member for fastening the printed circuit board of the driving circuit unit to the top chassis; a front case for receiving the liquid crystal display; and a fixing member for fixing the top chassis of the liquid crystal display to the front case. 
         [0022]    The top chassis may include a coupling portion, the printed circuit board includes a base plate on which the circuit component is mounted and a protruding portion formed on a side of the base plate, and the fastening member may be fastened to the coupling portion of the top chassis and the protruding portion of the printed circuit board. 
         [0023]    The fastening member may include a body portion, a first fastening portion formed in the body portion, and a second fastening portion formed in the body portion to be spaced apart from the first fastening portion; and the first fastening portion may be fastened to the protruding portion of the printed circuit board and the second fastening portion may be fastened to the coupling portion of the top chassis. 
         [0024]    The coupling portion of the top chassis may be a protrusion formed so that both ends thereof are perforated by a hole formed in each end, the front case may have a fastening hole formed therein, and the fixing member may be inserted in the fastening hole of the case and the coupling portion of the top chassis. 
         [0025]    The tablet computer may further include a backlight unit for providing light to the liquid crystal display panel; a digitizer for inputting display panel location coordinates; and a mold frame having first and second receiving spaces formed therein, the liquid crystal display panel and the backlight unit being accommodated in the first receiving space, and the digitizer and the printed circuit board being accommodated in the second receiving space. 
         [0026]    The digitizer may be disposed between the mold frame and the printed circuit board. 
         [0027]    The driving circuit unit may further include a flexible printed circuit board for connecting the printed circuit board and the liquid crystal display panel, and the flexible printed circuit board may be bent along a sidewall of the mold frame and disposed on the digitizer. 
         [0028]    The fastening member may be made of a non-conductive elastic material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The above and other aspects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: 
           [0030]      FIG. 1  is an exploded perspective view of a liquid crystal display according to an embodiment of the present invention; 
           [0031]      FIG. 2  is a sectional view of the liquid crystal display shown in  FIG. 1 ; 
           [0032]      FIGS. 3A to 3C  are schematic perspective views and a sectional view of a fastening member for fastening a printed circuit board of the liquid crystal display to a top chassis; 
           [0033]      FIGS. 4A and 4B  are a schematic perspective view and a partial enlarged view of the liquid crystal display, wherein the fastening member is not yet fastened to the printed circuit board; 
           [0034]      FIG. 5  is a rear perspective view of a mold frame and the top chassis of the liquid crystal display according to the embodiment of the present invention; 
           [0035]      FIGS. 6A to 6C  are perspective views showing a process of fastening the printed circuit board to the top chassis; 
           [0036]      FIGS. 7 to 9  are views showing modified examples of the fastening member of the liquid crystal display according to the present invention; and 
           [0037]      FIG. 10  is a schematic exploded perspective view of a tablet personal computer having the liquid crystal display according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0038]    Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. 
         [0039]      FIG. 1  is an exploded perspective view of a liquid crystal display according to the embodiment of the present invention, and  FIG. 2  is a sectional view of the liquid crystal display shown in  FIG. 1 . 
         [0040]    Referring to  FIGS. 1 and 2 , the liquid crystal display includes a liquid crystal display panel  100 , a driving circuit unit  200 , a top chassis  300 , a back cover  350 , a light source unit  400 , a light guide plate  500 , a digitizer  600 , optical sheets  700 , a mold frame  800  and fastening members  900 . 
         [0041]    The liquid crystal display panel  100  includes a color filter substrate  110  and a thin film transistor (TFT) substrate  120 . The color filter substrate  110  is a substrate on which RGB filters displaying a predetermined color when light passes therethrough are formed through a thin film process. A common electrode made of transparent conductor such indium tin oxide (ITO), indium zinc oxide (IZO) or the like is formed on an entire surface of the color filter substrate. The TFT substrate  120  is a transparent glass substrate on which TFTs are formed in a matrix form. In each TFT, a data line is connected to a source terminal, a gate line is connected to a gate terminal, and a pixel electrode, which is a transparent electrode made of transparent conductive material, is connected to a drain terminal. Accordingly, when an electric signal is applied to the gate line, the TFT is turned on, so that an electric signal required for forming an image is applied to the drain terminal and the associated pixel electrode. Once the TFT is turned-on, an electric field is formed between the pixel electrode of the TFT substrate and the common electrode of the color filter substrate. Due to this electric field, the arrangement of liquid crystal material interposed between the TFT substrate and the color filter substrate is changed and the light transmissivity is changed according to the changed arrangement, thereby displaying the desired image. 
         [0042]    In order to drive the liquid display panel  100 , the driving circuit unit  200  serves to apply a gate signal to the gate line of the liquid display panel  100  and a data signal to the data line. 
         [0043]    The driving circuit unit  200  includes a flexible printed circuit board  210 , driving integrated circuits (ICs)  220  and a printed circuit board  250 . 
         [0044]    The printed circuit board  250  includes a base plate  230  on which various kinds of circuit components are mounted and protruding portions  240  formed at both sides of the base plate  230 . The circuit components required for driving the liquid crystal display panel including a control IC, such as a DC-DC converter circuit for generating various kinds of voltages, a gamma reference voltage generator for outputting a gray scale voltage and the like, are mounted to the base plate  230  of the printed circuit board. The protruding portions  240  are fastened to first fastening portions  920  (see  FIGS. 3A to 3C ) of the fastening members  900 , which will be described below. The protruding portions  240  may be formed integrally with the base plate  230 . 
         [0045]    The flexible printed circuit board  210  electrically connects the printed circuit board  250  and the TFT substrate  120  of the liquid crystal display panel  100 . The driving ICs  220  are mounted to the flexible printed circuit board  210 , so that RGB (read, green and blue) signals generated in the printed circuit board  250 , electric power and the like are transmitted to the liquid crystal display panel  100 . Although a tape-automated bonding (TAB) mounting method is employed in the embodiment of the present invention, a chip on glass (COG) mounting method in which the driving IC  220  is not mounted on the flexible printed circuit board  210  but mounted on a thin film transistor substrate may alternatively be employed. 
         [0046]    The top chassis  300 , which is formed in the shape of a rectangular frame, includes a plane portion  301  and side wall portions  305  bent at a right angle from the plane portion  301 . The plane portion  301  of the top chassis overlaps the edges of the liquid crystal display panel  100  and the driving circuit unit  200  to retain them in place and to protect them against an external shock. Coupling portions  310  are formed on two of the side wall portions  305  of the top chassis  300 . Each of the coupling portions  310  may be formed in the shape of a protrusion. That is, the coupling portion  310  protrudes inwardly, i.e., into the space in which the liquid crystal display panel  100  is accommodated. The coupling portions  310  may be formed integrally with the side wall portions  305  of the top chassis  300 , and each of the coupling portions  310  may have a hole  312  formed in each of the ends thereof, as shown in  FIG. 6A . In a process of manufacturing the top chassis  300 , a portion of the side wall portion  305  can be made to protrude by partially pressing the side wall portion  305  of the top chassis  300 , to thereby form the coupling portion  310 . 
         [0047]    The light source unit  400  includes a lamp  410  and a lamp reflector  430 . A cold cathode fluorescent lamp or an external electrode fluorescent lamp may be used as the lamp  410 . Although the lamp  410  may be formed in a linear shape as shown in the figure, the lamp is not limited to that shape. The lamp reflector  430  reflects light radially emitted from the lamp  410  to the light guide plate  500 . Then the light exits from the light guide plate  500  towards the display panel to maximize the light use efficiency. Although the lamp is used as the light source utilized in the light source unit  400  in this embodiment, the present invention is not limited thereto. That is, various kinds of light sources, such as the light emitting diode, may be used. 
         [0048]    The light guide plate  500  is coupled with the lamp reflector  430 . With the light guide plate, the distribution of light from the linear shaped light source unit  400  is converted into that of a surface light source. The optical sheets  700  are disposed over the light guide plate  500  to make the distribution of light emitted from the light guide plate  500  more uniform in intensity. 
         [0049]    The digitizer  600  reads the two-dimensional location coordinates, X-Y, of the location of a stylus pen on the display screen. The digitizer  600  converts location coordinates, of the stylus pen on the liquid crystal display panel  100 , into an electric signal. The digitizer  600  decomposes an image written on the screen, be it a picture, a line of text or the like into electronic bits and stores them in a computer, and replays the stored data to display the original image. The digitizer  600  is connected to the driving circuit unit  200  for driving the liquid crystal display panel  100  and displays the input location coordinate converted into the electric signal on the liquid crystal display panel  100 . 
         [0050]    The mold frame  800  has a first receiving space and a second receiving space formed therein. The first receiving space is an upper receiving space facing the liquid crystal display panel  100 . And the second receiving space is a lower receiving space facing the back cover  350 . A backlight unit, including the light source unit  400 , the light guide plate  500 , and the optical sheet  700  and the liquid crystal display panel  100  are accommodated in the first receiving space of the mold frame  800 . The digitizer  600  and the printed circuit board  250  of the driving circuit unit  200  are accommodated in the second receiving space. The flexible printed circuit board  210  of the driving circuit unit  200  is bent along a sidewall of the mold frame  800 , so that the printed circuit board  250 , connected to one end of the flexible printed circuit board  210 , is disposed in the second receiving space of the mold frame  800 . The digitizer  600  is first disposed in the second receiving space of the mold frame  800 , and the printed circuit board  250  is disposed under the digitizer  600  (see  FIG. 2 ). That is, the digitizer  600  is disposed between the mold frame  800  and the printed circuit board  250 . 
         [0051]    The fastening members  900  fix the printed circuit board  250  of the driving circuit unit  200  to the liquid crystal display. The fastening members  900  are fastened to the coupling portions  310  of the top chassis  300  and the protruding portions  240  of the printed circuit board  250 , respectively. That is, the protruding portions  240  of the printed circuit board  250  are inserted into the fastening members  900  to be fixed thereto and the fastening members  900  are fastened to the coupling portions  310  of the top chassis  300  to be fixed thereto, respectively, whereby the printed circuit board  250  is fixed to the top chassis  300 . The fastening member  900  may be made of a non-conductive elastic material such as silicon rubber. The configuration and fastening structure of the fastening member  900  will be described in detail below. 
         [0052]    The back cover  350  is installed under the mold frame  800  and supports the digitizer  600 . 
         [0053]      FIGS. 3A to 3C  are schematic perspective views and a sectional view of the fastening member for fastening the printed circuit board of the liquid crystal display with the top chassis, and  FIGS. 4A and 4B  are a schematic perspective view and a partial enlarged view of the liquid crystal display, wherein the fastening member is not yet fastened with the printed circuit board. 
         [0054]    Referring to  FIGS. 3A to 3C , the fastening member  900  includes a body portion  910 , a first fastening portion  920  and a second fastening portion  930 . 
         [0055]    The body portion  910  includes a first body  911  and a second body  915  bent from the first body  911 . The first fastening portion  920  is formed in the first body  911 , and the second fastening portion  930  is formed in the second body  915 . The first fastening portion  920  is formed in the shape of a groove, and the second fastening portion  930  may be formed in the shape of a through hole. 
         [0056]    The first fastening portion  920  of the fastening member  900  is formed corresponding to the shape and size of the protruding portion  240  so that the protruding portion  240  formed at both sides of the base plate  230  of the printed circuit board  250  is inserted into the first fastening portion  920  (see  FIGS. 4A and 4B ). Also, the second fastening portion  930  of the fastening member  900  is formed corresponding to the shape and size of the coupling portion  310  so that the protrusion-shaped coupling portion  310  (see  FIG. 5 ) formed on the sidewall of the top chassis  300  may be inserted into the second fastening portion  930 . 
         [0057]    Although the body portion  910  includes the first body  911  and the second body  915  forming generally an “L” shape in this embodiment, the shape of the body portion  910  is not limited to an “L” shape. That is, the body portion may be formed in various shapes, for example, a hexahedral shape (see  FIG. 7 ). 
         [0058]    The fastening member  900  is made of a non-conductive elastic material such as silicon rubber. The digitizer  600  may malfunction when it is brought into contact with metallic materials. Accordingly, it is preferred that the fastening member which can possibly come in contact with the digitizer  600  be made of a non-conductive and elastic material to prevent malfunction of the digitizer  600 . 
         [0059]      FIG. 5  is a rear perspective view of the mold frame and the top chassis of the liquid crystal display according to the embodiment of the present invention.  FIG. 5  shows the mold frame  800  and the top chassis  300  of the liquid crystal display which are fastened together. 
         [0060]    The coupling portions  310  are formed to inwardly protrude at two sidewalls of the top chassis  300 . The coupling portions  310  are formed integrally with the top chassis  300 . In this embodiment, each end of the coupling portions  310  may be formed with a hole therein. However, the shape of the coupling portion  310  is not limited to coupling portions having holes. In a region of the mold frame  800  corresponding to a position of the coupling portion  310 , a receiving portion  830  is formed by removing a portion of a sidewall of the mold frame  800  in order to accommodate the fastening member  900 . 
         [0061]      FIGS. 6A to 6C  are perspective views showing a process of fastening the printed circuit board to the top chassis. 
         [0062]    Referring to  FIGS. 6A to 6C , the first fastening portions  920  of the fastening members  900  are aligned with the protruding portions  240  of the printed circuit board  250 . And then, the protruding portions  240  of the printed circuit board  250  are inserted into and fastened to the first fastening portions  920  formed in a shape of a groove (see  FIG. 6A ). 
         [0063]    Next, the second fastening portions  930  of the fastening members  900  are engaged with the protrusion-shaped coupling portions  310  of the top chassis  300  and fixed thereto (see  FIGS. 6B and 6C ). 
         [0064]    With the printed circuit board  250  fixed to the top chassis  300  by means of the fastening members  900 , and with the fastening members  900  made of non-conductive elastic material, as in this embodiment of the present invention, malfunction of the digitizer  600  is prevented when the fastening member  900  is brought into contact with the digitizer  600 . In addition, since the fastening members  900  absorb shocks and vibrations, the possibility that the printed circuit board is damaged by an externally applied shock or vibration is remarkably reduced. 
         [0065]      FIGS. 7 to 9  show exemplary modifications of the fastening member of the liquid crystal display of the present invention. 
         [0066]    Referring to  FIG. 7 , a fastening member  900  includes a body portion  910 , a first fastening portion  920  and a second fastening portion  930 . The body portion  910  is formed in a generally rectangular parallelepiped shape. The first fastening portion  920  is formed in a first side of the body portion  910  and the second fastening portion  930  is formed in a second side opposite to the first side. The first fastening portion  920  is formed in the shape of a groove corresponding to a protruding portion  240  of a printed circuit board  250 , and the second fastening portion  930  is formed in the shape a blind hole or a through hole corresponding to the shape and the size of a protrusion-shaped coupling portion  310  formed on a sidewall of a top chassis  300 . 
         [0067]    Referring to  FIG. 8 , a fastening member  900  includes a body portion  910  generally formed in an “L” shape, a first fastening portion  920  and a second fastening portion  930 . The first fastening portion  920  is formed in the shape of a groove in a first side of the body portion  910 , and the second fastening portion  930  is formed in the shape of a through hole in a second side of the body portion  910 . 
         [0068]    A coupling portion  315  is formed in a sidewall of a top chassis  300 . The coupling portion  315  is formed in the shape of a through-hole. 
         [0069]    A protruding portion  240  of a printed circuit board  250  is inserted into the first fastening portion  920  of the fastening member  900 , and a fixing portion  330  is inserted into the second fastening portion  930  and the coupling portion  315  of the top chassis  300  to be fixed. A screw or the like may be used as the fixing portion  330 . 
         [0070]    Referring to  FIG. 9 , a fastening member  900  includes a body portion  910  generally formed in an “L” shape, a first fastening portion  920  and a second fastening portion  935 . The first fastening portion  920  is formed in the shape of a groove in a first side of the body portion  910 , and the second fastening portion  935  is formed in the shape of a protrusion on a second side of the body portion  910 . The second fastening portion  935  may be formed in a hollow shape, i.e., a pipe shape, or in a hollow cylindrical shape. A coupling portion  315  is formed in a sidewall of a top chassis  300 . The coupling portion  315  may be formed in the shape of a through hole. 
         [0071]    A protruding portion  240  of a printed circuit board  250  is inserted into the first fastening portion  920  of the fastening member  900 . The second fastening portion  935  is inserted in and fixed to the coupling portion  315  of the top chassis  300 . 
         [0072]      FIG. 10  is a schematic exploded perspective view of a tablet computer having the liquid crystal display according to the present invention. 
         [0073]    Referring to  FIG. 10 , a tablet computer includes a liquid crystal display, a computer main body (not shown), a front case  1100  and a rear case  1300  for receiving the liquid crystal display and the computer main body. 
         [0074]    The liquid crystal display includes a liquid crystal display panel  100 , a driving circuit unit  200 , a top chassis  300 , a back cover  350 , a lamp unit  400 , a light guide plate  500 , a digitizer  600 , optical sheets  700 , a mold frame  800  and fastening members  900 . 
         [0075]    Coupling portions  310  are formed in the top chassis  300 . Each coupling portion  310  is formed as a protrusion, protruding inwardly into the space in which the liquid display panel is accommodated, and a hole  312 , as shown in  FIG. 6A , extending into the protrusion from the outer surface of the top chassis. A printed circuit board  250  of the driving circuit unit  200  includes a base plate  230 , on which circuit components (not shown) are mounted, and protruding portions  240  formed in both sides of the base plate  230 . 
         [0076]    First fastening portions  920  of the fastening members  900  are fastened to the protruding portions  240  of the printed circuit board  250 , and second fastening portions  930  are fastened to protrusions of the coupling portions  310  of the top chassis  300 , respectively. 
         [0077]    The front case  1100  is disposed over the top chassis  300  of the liquid crystal display, and the rear case  1300  is disposed under the back cover  350 . Like the top chassis  300 , the front case  1100  is formed in the shape of a rectangular frame and has fastening holes  1150  formed in side wall portions thereof. 
         [0078]    Fixing members  1200  are inserted into the fastening holes  1150  formed in the front case  1100  and the holes  312  of the coupling portions  310  of the top chassis  300  to fasten the front case to the top chassis, and thereby fasten the liquid crystal display to the front case. Although a screw or the like may be used as the fixing member  1200 , the present invention is not limited thereto. 
         [0079]    According to the present invention as described above, a printed circuit substrate is fixed by means of fastening members made of non-conductive elastic material, so that contact between the fastening members and a digitizer will not result in malfunction of the digitizer. In addition, the fastening members absorb shocks and vibrations and thus decrease the possibility that the printed circuit board will be damaged by externally applied shocks and vibrations. 
         [0080]    In addition, a tablet computer can be easily assembled, thereby being made ultra-thin in a simplified manner. 
         [0081]    The above descriptions are merely exemplary embodiments of a liquid crystal display and a tablet computer having the same according to the present invention, so that the present invention is not limited thereto. The true scope of the present invention should be defined to the extent that those skilled in the art can make various modifications and changes thereto without departing from the scope of the invention, as defined by the appended claims.