Abstract:
An inverter for a liquid crystal display device and a liquid crystal display module using the inverter are provided. The inverter includes a circuit board defining a hole through itself, and a transformer inversely inserted into the hole of the circuit. The transformer generates a high voltage.

Description:
[0001]    This application claims the benefit of Korean Patent Application No. 10-2006-0049228 filed in Korea on Jun. 1, 2006, which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an inverter for a backlight unit and an LCD module using the same. 
         [0004]    2. Discussion of the Related Art 
         [0005]    In general, an active matrix (AM) type LCD device displays moving images using thin film transistors (hereinafter, referred to as “TFTs”) as switching elements. In comparison with a cathode ray tube (CRT), the LCD device can have a smaller size. Thus, the LCD device may be used in a wide variety of applications, such as personal computers, notebook computers, office equipment, and mobile phones. 
         [0006]    The LCD device is not a self-lighting emission device. In this respect, the LCD device necessarily requires a light source, for example, a backlight unit, which is operated by an inverter. Among various components provided in the LCD device, the backlight unit consumes the most power. 
         [0007]    The inverter that drives the backlight unit is generally divided into a DC/DC inverter and a DC/AC inverter. In this case, the DC/DC inverter generates a DC voltage by a pulse width modulation (PWM) method. Also, the DC/AC inverter converts the DC voltage supplied from the DC/DC converter into a high AC voltage having a level suitable for driving a lamp. However, the inverter for the LCD device of the related art consumes a large amount of power due to the low efficiency of a transformer included in the DC/AC inverter. 
         [0008]      FIG. 1  is an exploded perspective view of a related art LCD device. 
         [0009]    As shown in  FIG. 1 , the related art LCD device includes an LCD panel  30  to display images and a backlight unit. The backlight unit includes a fluorescent lamp  31  to emit light, a U-shaped lamp housing  32  to surround the fluorescent lamp  31 , a light-diffusion sheet  35 , a first prism sheet  37 , a second prism sheet  36  and a protective sheet  38  provided in sequence below the LCD panel  30 . The backlight further includes a light-guiding plate  33 , a reflective sheet  34 , and main support  39  to support and fix the LCD panel  30  and the backlight unit. 
         [0010]    A display area (A) of LCD panel  30  is illuminated with the light emitted from the backlight unit. Although not shown, the display area (A) of LCD panel  30  is comprised of two transparent substrates bonded to each other, and a liquid crystal layer formed by providing liquid crystal material in an inner space between the two transparent substrates. Further, two polarizing plates are adhered to respective outer surfaces of the two substrates. A driving circuit  40  is provided to drive the display area (A). 
         [0011]    The backlight unit operates as follows. When the fluorescent lamp  31  provided at one end of the light-guiding plate  33  is turned on, the light emitted from the fluorescent lamp  31  is reflected by the lamp housing  32 . Then, the reflected light is transmitted to an end of light-guiding plate  33 , in which the fluorescent lamp  31  is not provided, through a cross section of light-guiding plate  33 . As a result, the light is diffused to the entire surface of light-guiding plate  33 , and the display area (A) of LCD panel is illuminated by the light using the light-diffusion plate  35 . 
         [0012]    In the related art LCD device, thin film transistors formed in the LCD panel control respective pixels according to a signal provided by the driving circuit  40  so that the light for the display area (A) of LCD panel is selectively transmitted. By controlling light transmission through the respective pixels, the image is displayed on the display area (A) of LCD panel. 
         [0013]      FIG. 2  is an exploded perspective view of a transformer for a lamp-driving circuit of an LCD device according to the related art.  FIG. 3  is a perspective view of the transformer shown in  FIG. 2 . 
         [0014]    As shown in  FIGS. 2 and 3 , the transformer for the inverter of the LCD device comprises a bobbin  1 , on which coil  2  is wound, provided with partitions  1   a  at fixed intervals, and ferrite cores  4   a  and  4   b  inserted into the center of bobbin  1 . Here, the bobbin  1  having the partitions  1   a  is formed of a plastic material. The ferrite cores  4   a  and  4   b  are formed by mixing minutely powdered iron oxide and manganese together, thereby being able to guide a magnetic flux. 
         [0015]    Each of the ferrite cores  4   a  and  4   b  is formed in the shape of an “E” wherein the central part of the “E”-shaped ferrite core penetrates the center of bobbin  1 . The sidewalls of ferrite cores  4   a  and  4   b  surround the sides of bobbin  1  having the coil  2  wound thereon. 
         [0016]    Based on a predetermined winding ratio, the winding number of coil  2  at a first side is different from the winding number of coil  2  at a second side. A current flows through the coil  2 . 
         [0017]    At both ends of the bobbin  1 , there are lead pins  3 . In detail, the coil  2  is wound on each grooved coil-winding part between the partitions  1   a . Then, a tape is wound on the coil-winding part of bobbin  1  having the coil  2  wound thereon. After assembling the ferrite cores  4   a  and  4   b  into the bobbin  1 , the ferrite cores  4   a  and  4   b  are bound up with an adhesive tape. 
         [0018]    The coil-winding parts having the coil  2  wound thereon are divided by the sidewalls of bobbin  1  and partitions  1   a  of bobbin  1 . In this case, the coil-winding parts include a low tension part, a medium tension part, and a high tension part. 
         [0019]      FIG. 4  is a cross sectional view illustrating a lower part of the LCD module according to the related art including an inverter, a bottom cover, and a cover shield. 
         [0020]    As shown in  FIG. 4 , an inverter  170  is positioned at a predetermined interval from a rear surface of bottom cover  150 . Also, a cover shield  160  covers the inverter  170 . Here, the inverter  170  comprises a printed circuit board (PCB)  190 , a transformer  180 , and high-tension and low-tension patterns  182 . There is a connector (not shown) in the PCB  190 . Through the connector of PCB  190 , the inverter  170  is connected to a fluorescent lamp (not shown) so that power is supplied to the fluorescent lamp. Also, a plurality of integrated circuits (ICs) are provided in the PCB  190 , thereby controlling the operation of the inverter  170 . 
         [0021]    The transformer  180  comprises a core to guide a magnetic flux; a bobbin (not shown) having first and second coils (not shown) wound thereon; and first and second lead pins  183  and  184  respectively connected to the first and second coils at both sides of the bobbin (not shown). The first and second lead pins  183  and  184  are soldered on the PCB  190 . As the transformer  180  is supplied with DC voltage outputted from the PCB  190 , the transformer  180  generates AC voltage to drive the lamp. 
         [0022]    The total thickness of inverter  170  is measured by adding the thickness of PCB  190  and the thickness of transformer  180  together. In this case, the transformer  180  is thicker than the PCB  190 . Thus, the total thickness of inverter  170  is determined by the thickness of transformer  180 . The transformer  180  has a considerable thickness so that the inverter  170  also has a considerable thickness. The rear surface of the cover shield  160  to cover the inverter  170  is formed at a predetermined height from the rear surface of PCB  190  to the upper surface of transformer  180 . That is, the transformer  180  is positioned at a predetermined interval from the cover shield  160 , thereby defining an insulation distance. To obtain an insulation distance between the bottom cover  150  and the transformer  180 , the transformer  180  is positioned at a predetermined interval from the bottom cover  150 . Accordingly, the thickness of LCD module is increased due to the thickness of the transformer  180 . 
         [0023]    If a high-tension voltage is supplied to a high-luminance lamp, the transformer  180  of the inverter  170  must be thick. In the related art structure, the total thickness of the LCD module is mostly due to the thickness of the transformer  180 . By supplying the high-tension voltage from the inverter  170 , the LCD module must be thicker. 
         [0024]    However, the related art inverter has the following disadvantages. First, it is difficult to decrease the total thickness of the inverter due to the thickness of the transformer used as a voltage-boosting means. In an LCD module for a television, the fluorescent lamps are arranged parallel to each other so that the cost of the inverter is decreased. Thus, the thickness of the transformer is increased to realize the high capacity so that the thickness of inverter as well as the total thickness of the LCD module is also increased. 
       SUMMARY OF THE INVENTION 
       [0025]    Accordingly, the present invention is directed to an inverter for an LCD device and an LCD module using the same that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
         [0026]    An object of the present invention is to provide an inverter for an LCD device to obtain an insulation distance between a cover shield and a bottom cover in a transformer and a high-tension pattern so that a total thickness of an LCD device and an LCD module using the same are decreased. 
         [0027]    Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0028]    To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, an inverter for a liquid crystal display (LCD) device comprises a circuit board defining a hole therethrough; and a transformer inversely inserted into the hole of the circuit, the transformer generating a high voltage. 
         [0029]    In another aspect, a liquid crystal display (LCD) module comprises an LCD panel; a backlight assembly including a light source to supply light to a rear surface of the LCD panel; a main support on which the LCD panel and the backlight assembly are supported; and an inverter including a circuit board defining a hole therethrough and a transformer inversely inserted into the hole of the circuit board, wherein the inverter supplies power to the light source of the backlight assembly. 
         [0030]    It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    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. In the drawings: 
           [0032]      FIG. 1  is an exploded perspective view of an LCD device according to the related art; 
           [0033]      FIG. 2  is an exploded perspective view of a transformer for a lamp-driving circuit of an LCD device according to the related art; 
           [0034]      FIG. 3  is a perspective view of a transformer of the type shown in  FIG. 2 ; 
           [0035]      FIG. 4  is a cross sectional view of a lower part of an LCD module according to the related art having an inverter, a bottom cover and a cover shield; 
           [0036]      FIG. 5  is a perspective view, illustrating an LCD module according to an exemplary embodiment of the present invention; and 
           [0037]      FIG. 6  is a cross sectional view of a lower part of the LCD module of  FIG. 5  illustrating an inverter, a bottom cover, and a cover shield. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Hereinafter, an inverter for an LCD device according to the present invention and an LCD module using the same will be described with reference to the accompanying drawings. 
         [0039]      FIG. 5  is a perspective view of an LCD module according to an exemplary embodiment of the present invention.  FIG. 6  is a cross sectional view of a lower part of the LCD module of  FIG. 5  illustrating an inverter, a bottom cover, and a cover shield. 
         [0040]    As shown in  FIG. 5 , the LCD module  200  according to an exemplary embodiment of the present invention includes an LCD panel  210 , a backlight assembly  220 , a main support  240 , a top case  230 , a bottom cover  250 , a cover shield  260 , and an inverter  270 . The LCD panel  210  includes upper and lower substrates  210   a  and  210   b  facing each other and a liquid crystal layer (not shown) formed between the upper and lower substrates  210   a  and  210   b . The lower substrate  210   b  has thin film transistors as switching elements, and the upper substrate  210   a  has a color filter layer. Images are displayed under the control of the thin film transistors being turned-on/off. 
         [0041]    The LCD panel  210  is connected to gate and source PCBs  215   a  and  215   b  which respectively output an image signal and a scanning signal to the LCD panel  210 . Also, the backlight assembly  220  is positioned underneath the LCD panel  210 , and the backlight assembly  220  supplies light to the LCD panel  210 . The backlight assembly  220  is a direct type backlight. A plurality of lamps  221  are arranged parallel to each other, a reflective sheet  222  is positioned underneath the plurality of lamps  221 , and a plurality of optical sheets  223  are provided on the plurality of lamps  221 . 
         [0042]    The LCD panel  210  and the backlight assembly  220  are positioned on the main support  240  so that the main support  240  stably supports and fixes the LCD panel  210  and the backlight assembly  220 . Also, the top case  230  covers the upper edges of LCD panel  210  and the lateral sides of main support  240  so that the upper edges of LCD panel  210  and the lateral sides of main support  240  are supported and protected by the top case  230 . The bottom cover  250  covers the bottom of main support  240  so that the bottom cover  250  protects the lower side of LCD module  200 . Thereafter, the bottom cover  250  is connected together with the top case  230  and the support main  240  by a connection part (not shown), thereby completing the module. 
         [0043]    Then, the inverter  270  is positioned underneath the bottom cover  250  so that the inverter  270  can supply power to the plurality of lamps  221 . The inverter  270  is covered with the cover shield  260 . The cover shield  260  and the bottom cover  250  cover the inverter  270  to protect the inverter  270  from the external impact. The cover shield  260  and the bottom cover  250  are formed of metal materials to block an electromagnetic wave. 
         [0044]    The inverter  270  includes a PCB  290  and a transformer  280 . Here, a connector (not shown) is positioned in the PCB  290  of inverter  270 . Through the connector (not shown), the inverter  270  is connected to the lamp  221  so that the lamp  221  is supplied with power. Also, the PCB  290  of inverter  270  is provided with a plurality of ICs (not shown) to control the operation of inverter  270 . 
         [0045]    As shown in  FIG. 6 , the transformer  280  of inverter  270  includes a core  281  to guide a magnetic flux; a bobbin (not shown) having first and second coils (not shown) wound thereon; first and second lead pins  283  and  284  respectively connected with the first and second coils and respectively positioned at both sides of bobbin (not shown); and high-tension and low-tension patterns  282  respectively connected with the first and second lead pins  283  and  284 . The first and second lead pins  283  and  284  are soldered on the PCB  290 . The transformer  280  is supplied with a DC voltage from the PCB  290  of inverter  270 , and the transformer  280  generates the AC voltage to drive the lamp  221 . 
         [0046]    The inverter  270  is positioned at a predetermined interval from the rear surface of bottom cover  250 . Also, the rear surface of cover shield  260  is positioned at a predetermined interval from the rear surface of PCB  290  of inverter  270 . To insert the transformer  280  into the PCB  290  of inverter  270 , a hole  295  is provided in the PCB  290  of inverter  270 . The hole  295  is open to the front and rear directions. After the transformer  280  is inversely inserted into the hole  295  of PCB  290 , the transformer  280  is soldered on the PCB  290 . 
         [0047]    For the hole  295  of PCB  290  on which the transformer  280  is soldered, there is an insulation material  285  to obtain a creeping distance between the high-tension and low-tension patterns  282 . That is, the core of transformer  280  is positioned toward the bottom cover  250 , and the first and second lead pins  283  and  284  are assembled into the PCB  290 , thereby forming the inverter  270 . To obtain the creeping distance of insulation distance, the gap of hole  295 , formed between the transformer  280  and the PCB  290 , should be filed with the insulation material  285 . 
         [0048]    In the above-mentioned structure, the thickness of inverter  270  is substantially identical to that of the transformer  280 . For example, on inserting the transformer  280  into the hole  295  of PCB  290 , if the transformer  280  is thicker than the PCB  290 , the thickness of inverter  270  corresponds to the thickness of transformer  280 . Conversely, if the transformer  280  is thinner than the PCB  290 , the thickness of inverter  270  corresponds to the value measured by subtracting the insertion depth of transformer  280  from the sum of the thickness of transformer  280  and the thickness of PCB  290 . Even though the insertion depth of transformer  280  is smaller than the thickness of PCB  290  of inverter  270 , the thickness of transformer  280  is relatively large so that the thickness of inverter  270  is about the thickness of transformer  280 . 
         [0049]    As a result, in comparison to the related art inverter having a thickness corresponding to the sum of the thickness of transformer and the thickness of the PCB, the inverter of the present invention has a smaller thickness. 
         [0050]    Also, the height from the rear surface of PCB  290  to the rear surface of cover shield  260  is less than that of the related art. In comparison to the height to the cover shield  160  of the related art shown in the dotted line of  FIG. 6 , the height from the rear surface of PCB  290  to the cover shield  260  is decreased in proportion to the depth (H) of transformer  280  inserted into the hole  295 . 
         [0051]    In comparison to the related art, the inverter of the present invention is formed with the cover shield having a height that is decreased in proportion to the insertion depth of transformer  280 , thereby also decreasing the thickness of the LCD module  200 . In addition, the transformer is inserted into the hole formed in the PCB, thereby decreasing the total thickness of inverter. As a result, the height of the cover shield  260  is decreased so that the total thickness of LCD module  200  is decreased. 
         [0052]    As mentioned above, the inverter for the LCD device according to the present invention and the LCD module using the same has numerous advantages. For example, the transformer is inversely inserted into the hole formed in the PCB of inverter such that the core is formed toward the bottom cover, thereby decreasing the total thickness of inverter. Accordingly, the height of cover shield is decreased so that the total thickness of the LCD module is decreased. 
         [0053]    The above-mentioned structure to decrease the total thickness of inverter may be applicable to all kinds of LCD devices without regard to the type of inverter. 
         [0054]    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 inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.