Abstract:
There is provided a liquid crystal display comprising a driving circuit unit. The driving circuit unit has an adaptor and an inverter for converting an input voltage integrally configured with each other. Thus, the liquid crystal display is made small. The liquid crystal display can stably and efficiently display an image through a smaller liquid crystal when an external voltage is supplied to each circuit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a liquid crystal display comprising a driving circuit unit, and more particularly, to a liquid crystal display comprising a driving circuit unit having an adaptor and an inverter for converting an input voltage integrally configured with each other, and an LCD module having an LED module and an LED drive, thereby making the liquid crystal display suitable as a small or middle-sized liquid crystal display and stably and efficiently displaying an image. 
         [0003]    2. Discussion of Related Art 
         [0004]    In general, a liquid crystal display (LCD) has bee used to display an image from a computer. With the recent development of technology, an LCD television has been developed. 
         [0005]    The liquid crystal display has been used as a monitor for a desktop computer, and a portable computer such as a notebook computer. Recently, the liquid crystal display is applied to a variety of consumer electronic appliances such as portable phones, refrigerators, televisions, and washing machines. 
         [0006]    A liquid crystal display displays an image through molecule arrangement of liquid crystals changing as a voltage is supplied to pixels. The liquid crystal display itself cannot emit light and be used at dark places. For use at dark places, the liquid crystal display comprises a back light lamp for surface-illuminating an information display panel in a uniform manner. 
         [0007]    As the liquid crystal display comprises the back light lamp, a power source is necessary. The power source includes a commercial voltage of 220V widely used at homes, and a charged voltage of a rechargeable battery. 
         [0008]    However, a voltage on the order of 1000 to 1500V is required for driving the back light lamp. To this end, a separate adaptor converts such a high voltage into a low voltage, and an inverter converts the low voltage into a high AC voltage. 
         [0009]      FIG. 1  is a schematic view illustrating a structure of a conventional liquid crystal display, and  FIG. 2  is a block diagram illustrating a conventional liquid crystal display. 
         [0010]    Referring to  FIGS. 1 and 2 , first, a power line  110  is provided for taking and supplying an external voltage, and an adaptor  120  for converting an AC voltage into a DC voltage is connected to the power line  110 . An interface substrate  140  comprising a signal processing unit  142  for processing an image signal is connected to the adaptor  120 . An inverter  160  is connected to the interface substrate  140 . The inverter  160  converts a DC voltage from the interface substrate  140  into an AC voltage having a desired size and frequency. 
         [0011]    Meanwhile, a power connector  180  is connected to the inverter  160 . 
         [0012]    The power connector  180  is for supplying the AC voltage from the inverter  160  to back light lamps  202 , which are mounted on and beneath a liquid crystal display module  200 . 
         [0013]    A circuit of such a liquid crystal display will now be described with reference to  FIG. 2 . First, the liquid crystal display comprises an adaptor  120  for taking an external voltage, an interface substrate  140  having a signal processing unit  142  for receiving a rectified voltage from the adaptor  120  and processing a signal, and an inverter  160  for receiving image information from the interface substrate  140 , dropping a voltage to a predetermined voltage, and supplying it to the back light lamps  202 . 
         [0014]    Specifically, the adaptor  120  comprises an AC power input unit  210  for taking the external AC voltage, a first rectifying unit  220  for rectifying the AC voltage from the AC power input unit  210  into a DC voltage, a first converting unit  230  for converting the DC voltage rectified by the first rectifying unit  220 , a second rectifying unit  240  for further rectifying the DC voltage from the first converting unit  230 , an error detection/control-signal feedback circuit unit  250  for detecting an output voltage of the second rectifying unit  240  and stabilizing the output voltage according to a load, and a first power control unit  260  for receiving the stabilized output signal from the error detection/control-signal feedback circuit unit  250  and controlling the first converting unit  230 . 
         [0015]    The signal processing unit  142  of the interface substrate  140  comprises a DC converting unit  310  for receiving the rectified DC voltage from the second rectifying unit  240  of the adaptor  120  and converting it into a low voltage suitable for video signal processing, a noise removing circuit unit  320  for removing a noise from the rectified DC voltage from the second rectifying unit  240 , an image signal processing unit  330  for receiving a low voltage from the DC converting unit  310  and processing the video signal, and a microcomputer  340  for controlling the image signal processing unit  330 . 
         [0016]    The inverter  160  comprises a second power control unit  410  for receiving the DC voltage without a noise from the noise removing circuit unit  320  and converting it to an AC voltage, a luminance adjusting circuit unit  420  for adjusting luminance under control of the microcomputer  340 , a second converting unit  430  for receiving the AC voltage from the second power control unit  410  and converting it into a suitable voltage, an error detection/control-signal feedback circuit unit  440  for detecting the output voltage of the second converting unit  430  and stabilizing the output voltage according to a load, and a protecting circuit unit  450  for controlling overcurrent and overvoltage to be a proper level to protect the circuit. 
         [0017]    In this liquid crystal display, however, the adaptor  120  has a complex appearance since it is designed to be exposed to the exterior and connected to the power line  110 . The structure of the liquid crystal display is complex because the adaptor  120  is a separate entity. 
         [0018]    In addition, the signal processing unit  142  of the interface substrate  140  must convert the DC voltage from the adaptor  120  into a low DC level (e.g., about 5V or less) required for operation of the image signal processing unit. This degrades conversion efficiency. 
         [0019]    Furthermore, the above liquid crystal display is suitable in large size, but is not suitable as a small or middle-sized liquid crystal display having an LED module. 
         [0020]    Recently, with the advent of various multimedia devices, such as image-communicable portable phones, MP3 players, portable multimedia players (PMPs), PDPs, personal digital assistants (PDAs), and electronic dictionaries, by virtue of technical development of electronic devices, the devices are gradually made small. Thus, there is a need for a liquid crystal display suitable for small multimedia devices. 
       SUMMARY OF THE INVENTION 
       [0021]    An aspect of the present invention provides a liquid crystal display comprising a driving circuit unit having an adaptor and an inverter integrally configured with each other. 
         [0022]    Another aspect of the present invention provides a small or middle-sized liquid crystal display having an LED module in which a driving circuit unit for supplying a power voltage is integrally configured with the liquid crystal display in order to improve power efficiency. 
         [0023]    Still another aspect of the present invention provides a liquid crystal display comprising a driving circuit unit in which the liquid crystal display comprises a power supply unit and an inverter, and an LCD module includes an LED module and an LED drive controlled by a timing control unit, which makes the liquid crystal display suitable as a small or middle-sized liquid crystal display. 
         [0024]    To achieve the objects, a driving circuit unit comprising a power supply and an inverter integrally configured with each other is provided in an LCD module. 
         [0025]    Exemplary embodiments of the present invention provide a liquid crystal display (LCD) comprising an LCD module, a back light disposed at one side of the LCD module for emitting light, and a driving circuit unit for driving the back light, and the driving circuit unit comprises: an AC power supply unit for supplying an external voltage; a first rectifying unit fro rectifying the external voltage from the AC power supply unit into a DC voltage; a first converting unit for converting the rectified DC voltage from the first rectifying unit; a second rectifying unit for further rectifying the converted voltage from the first converting unit; a DC converting unit for converting the rectified DC voltage from the second rectifying unit; an inverter power driving unit for receiving the converted current from the DC converting unit to drive an inverter; an inverter high-frequency driving circuit unit driven by the inverter power driving unit for driving a switching circuit and performing comparison, detection and control on an input voltage; a second converting unit for converting an output voltage of the inverter high-frequency driving circuit unit into a voltage having a predetermined level; an LCD module driven by a current from the second converting unit, LCD module including a timing control unit and an LED drive and being integrally configured with the back light; an image processing unit for processing a video signal using the DC converting unit driven by the rectified DC voltage from the second rectifying unit; and a microcomputer for receiving an image signal processed by the image processing unit and controlling luminance and the image signal. 
         [0026]    The display may further comprise a protecting circuit unit for detecting an overvoltage output from the second converting unit to the back light to perform protection. The display may further comprise a noise removing circuit unit for performing comparison and detection on a voltage output from the second rectifying unit to the DC converting unit to remove a noise from the output voltage. 
         [0027]    Other embodiments of the present invention provide a liquid crystal display comprising an LCD module having an LED module, a back light disposed at one side of the LCD module for emitting light, and a driving circuit unit for driving the back light, and the liquid crystal display comprises: the LCD module including a timing control unit connected to an LCD panel; and a graphic control unit connected to the timing control unit of the LCD module and having an LED drive integrally mounted therewith for driving the LED module. 
         [0028]    Other embodiments of the present invention provide a liquid crystal display comprising an LCD module having an LED module, a back light disposed at one side of the LCD module for emitting light, and a driving circuit unit for driving the back light, and the liquid crystal display comprises: the LCD module including a timing control unit integrally configured with an LED drive and connected to an LCD panel; and a graphic control unit connected to the timing control unit of the LCD module for driving the timing control unit. 
         [0029]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail preferred embodiments thereof with reference to the attached drawings in which: 
           [0031]      FIG. 1  is a schematic view illustrating a structure of a conventional liquid crystal display; 
           [0032]      FIG. 2  is a block diagram illustrating a conventional liquid crystal display; 
           [0033]      FIG. 3  is an exploded perspective view illustrating a liquid crystal display comprising a driving circuit unit according to the present invention; 
           [0034]      FIG. 4  is a schematic view illustrating a structure of a liquid crystal display comprising a driving circuit unit according to the present invention; 
           [0035]      FIG. 5  is a block diagram illustrating a liquid crystal display comprising a driving circuit unit according to the present invention; 
           [0036]      FIG. 6  is a block diagram illustrating a liquid crystal display comprising a driving circuit unit according to an embodiment of the present invention; 
           [0037]      FIG. 7  is a circuit diagram illustrating an LED drive for a liquid crystal display according to the present invention; 
           [0038]      FIG. 8  is a block diagram illustrating another embodiment of the present invention; and 
           [0039]      FIG. 9  is a block diagram illustrating still another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided as teaching examples of the invention. Like numbers refer to like element. 
         [0041]      FIG. 3  is an exploded perspective view illustrating a liquid crystal display comprising a driving circuit unit according to the present invention,  FIG. 4  is a schematic view illustrating a structure of a liquid crystal display comprising a driving circuit unit according to the present invention,  FIG. 5  is a block diagram illustrating a liquid crystal display comprising a driving circuit unit according to the present invention, and  FIG. 6  is a block diagram illustrating a liquid crystal display comprising a driving circuit unit according to an embodiment of the present invention. 
         [0042]      FIG. 7  is a circuit diagram illustrating an LED drive for a liquid crystal display according to the present invention,  FIG. 8  is a block diagram illustrating another embodiment of the present invention, and  FIG. 9  is a block diagram illustrating still another embodiment of the present invention. 
         [0043]    Referring to  FIG. 3 , the liquid crystal display of the present invention comprises front and rear cases  44  and  46 . The liquid crystal display further comprises an LCD panel  60  for displaying an image, and a back light  58  mounted below the LCD panel  60  for illuminating the LCD panel  60 , both of which are interposed between the front and rear cases  44  and  46 . 
         [0044]    The liquid crystal display further comprises a light guide plate  48  disposed on the back light  58 , and a diffusion sheet  52  disposed on the light guide plate  48 . The LCD panel  60  is disposed on the diffusion sheet  52 . 
         [0045]    The liquid crystal display further comprises a reflection sheet  50  disposed below the light guide plate  48 . 
         [0046]    The back light  58  comprises a fixing plate  62  extending in a longitudinal direction and having a bar shape, an LED fixing PCB  64  fixed on the fixing plate  62 , an LED drive  54  disposed at one side of a lower surface of the fixing plate  62 , and a plurality of LED lamps  56  fixed on the LED fixing PCB  64 . 
         [0047]    The LCD panel  60  comprises a driving circuit unit  100  for supplying a voltage to the back light  58  and the LCD panel  60  to drive them. 
         [0048]    The back light  58  having the above structure is disposed at a rear side of the light guide plate  48 . Accordingly, the back light  58  can perform a back lighting function with a higher luminance. 
         [0049]    The back light  58  comprises LED lamps  56 , which are typical LED lamps for emitting white color light. Alternatively, the LED lamps  56  may include lamps that can emit white color light through a combination of red, blue, and green LEDs. The LED lamps  56  are driven by the LED drive  54 . 
         [0050]    The LED drive  54  is integrally configured with an LCD module  200  that will be described later, and is detachably connected to the digital LCD drive circuit. That is, the LED drive  54  is integrally configured with the back light  58 , as in  FIG. 4 . 
         [0051]    Accordingly, it is unnecessary to provide a separate LED drive circuit. What is needed is that an LCD panel control signal and an LED control signal are supplied to the driving circuit unit  100 . 
         [0052]    The LED drive  54  of the back light  58  is electrically controlled by a timing control unit  70  connected thereto. 
         [0053]    Referring to  FIGS. 4 to 6 , the liquid crystal display according to the present invention further comprises a driving circuit unit  100  for converting a commercial AC voltage into a DC voltage and then into an AC voltage required for driving the back light  202 . The driving circuit unit  100  is connected to the back light  202  for driving the back light  202 . The back light  202  is electrically connected to the LCD module  200 . 
         [0054]    The driving circuit unit  100  comprises an AC power supply unit  10  for supplying a commercial AC voltage; a first rectifying unit  12  for rectifying the AC voltage from the AC power supply unit  10 ; a first converting unit  14  for converting the rectified DC voltage; a second rectifying unit  16  for further rectifying the DC voltage from the first converting unit  14 ; a DC converting unit  18  for detecting the rectified DC voltage from the second rectifying unit  16  and converting it into a voltage suitable for a load; a feedback control circuit unit  20  for detecting the voltage from the DC converting unit  18  and stabilizing it; and a switching circuit unit  22  for detecting a characteristic of the output voltage of the feedback control circuit unit  20 , performing comparison on the voltage, and controlling a pulse width. 
         [0055]    The driving circuit unit  100  further comprises an inverter power driving unit  24  driven by the DC voltage output from the DC converting unit  18 ; an inverter high-frequency driving circuit unit  26  for receiving the voltage from the inverter power driving unit  24  to drive the inverter, detecting and comparing the supplied DC voltage, and controlling the output voltage; an inverter transformer  28  driven by the output voltage of the inverter high-frequency driving circuit unit  26  for inducing a primary voltage toward a secondary side using magnetic induction of a core and a turn ratio of coils; and a second converting unit  30  for receiving the induced voltage from the inverter transformer  28  and further converting the DC voltage. The driving circuit unit  100  further comprises a protecting circuit unit  32  for controlling overcurrent and overvoltage output from the second converting unit  30  to be a suitable level in order to protect the circuit. 
         [0056]    The inverter high-frequency driving circuit unit  24  comprises a control IC, a high-frequency control circuit, and a switching circuit for driving and controlling the inverter. 
         [0057]    The high-frequency control circuit applies a switching signal to a switching circuit including a switching device such as one or a plurality of transistors or electric field transistors in order to switch the inverter transformer  28 . 
         [0058]    The second converting unit  30  is connected to the back light  202 . The second converting unit  30  drives the back light  202  by supplying a high voltage to the back light  202 . 
         [0059]    The LCD module  200  integrally configured with the back light  202  comprises an LED drive  54 , and a timing control unit  70  is connected to the LED drive  54 . 
         [0060]    Meanwhile, in order to process an image using a low voltage, the driving circuit unit  100  further comprises a DC converting unit  34  for receiving the DC voltage from the second rectifying unit  16 ; an image processing unit  36  for receiving a low DC voltage from the DC converting unit  34  and processing a video signal; and a microcomputer  38  for controlling the image processing unit  36 . 
         [0061]    The driving circuit unit  100  of the present invention drives the back light  202  and the LCD module  200 . 
         [0062]      FIG. 6  illustrates an embodiment of the present invention. The driving circuit unit  100  further comprises a luminance-adjusting circuit unit  40  for receiving the image-processed signal from the microcomputer  38  to adjust luminance of the liquid crystal display; and a noise removing circuit unit  42  for removing a noise from the DC voltage, which is sent from the second rectifying unit  16  to the DC converting unit  18 . 
         [0063]    In operation, first, the first rectifying unit  12  rectifies an AC voltage from the AC power supply unit  10  into a DC voltage, and the first converting unit  14  converts the DC voltage into a voltage having a predetermined level and inputs it to the second rectifying unit  16 . 
         [0064]    The second rectifying unit  16  further rectifies the DC voltage and inputs the resultant DC voltage to the DC converting unit  18 . 
         [0065]    The DC converting unit  18  converts the input voltage into a constant voltage for driving the inverter, and applies the constant voltage to the inverter power driving unit  24 . 
         [0066]    Meanwhile, the DC voltage from the second rectifying unit  16  is also input to the DC converting unit  34 . The DC converting unit  34  outputs a typical, low constant voltage and inputs it to the image processing unit  36 . Accordingly, the image processing unit  36  processes a video signal and drives the microcomputer  38 . 
         [0067]    As the output voltage of the DC converting unit  18  is applied to the inverter high-frequency driving circuit unit  26  via the inverter power driving unit  24 , the inverter high-frequency driving circuit unit  26  operates to switch the inverter transformer  28 . 
         [0068]    The inverter transformer  28  induces the primary voltage toward a secondary voltage to stabilize the voltage, and applies the stabilized voltage to the second converting unit  30 . The second converting unit  30  converts the voltage from the inverter transformer  28  into a high AC voltage required for driving the back light  202  and outputs the high AC voltage to drive the liquid crystal display. 
         [0069]    The second converting unit  30  drives the timing control unit  70 , which operates the LED drive  54  to drive the back light  202 . 
         [0070]      FIG. 7  is a circuit diagram illustrating an LED drive for a liquid crystal display according to the present invention,  FIG. 8  is a block diagram illustrating another embodiment of the present invention, and  FIG. 9  is a block diagram illustrating still another embodiment of the present invention. 
         [0071]    Referring to  FIGS. 8 to 9 , a graphic control unit  72  is connected to a computer, and the graphic control unit  72  is connected to the LCD module  200 . 
         [0072]    The LCD module  200  comprises an LCD panel  60 , a timing control unit  74  connected to the LCD panel  60 , and an LED module  204  disposed at a side of the LCD panel  60 . 
         [0073]    The graphic control unit  72  is connected with the timing control unit  70 . 
         [0074]    As shown in  FIG. 8 , the LED drive  54  is provided in the graphic control unit  72 , and the graphic control unit  72  is connected to the timing control unit  70 . 
         [0075]    The LED drive  54  is connected to the LED module  204  of the LCD module  200  for driving the LED module  204 . 
         [0076]    As shown in  FIG. 9 , the LED drive  54  of the present invention is provided in the timing control unit  70 , and drives the LED module  204  as it is connected with the timing control unit  70 . 
         [0077]    According to the present invention, by providing the driving circuit unit comprising the power supply and the inverter integrally configured with each other in the LCD module, the liquid crystal display can be made small. The driving circuit unit can be easily applied to a small or middle-sized liquid crystal display, thereby preventing power loss. 
         [0078]    According to the present invention, by providing the driving circuit unit comprising the power supply and the inverter integrally configured with each other in the LCD module, the liquid crystal display can be made small. The driving circuit unit can be easily disposed in a small or middle-sized liquid crystal display, thereby reducing manufacturing cost and the number of manufacture processes to improve productivity. 
         [0079]    Furthermore, the present invention can be easily applied to a small or middle-sized liquid crystal display, which makes it possible to prevent power loss and efficiently supply the power. 
         [0080]    The invention has been described using preferred exemplary embodiments. However, it is to be understood that the scope of the invention is not limited to the disclosed embodiments. On the contrary, the scope of the invention is intended to include various modifications and alternative arrangements within the capabilities of persons skilled in the art using presently known or future technologies and equivalents. The scope of the claims, therefore, should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.