Patent Publication Number: US-7724233-B2

Title: Driving circuit and LCD incorporating the same

Description:
FIELD OF THE INVENTION 
   The present invention relates to a driving circuit and a liquid crystal display (LCD) having the driving circuit. 
   GENERAL BACKGROUND 
   An LCD has the advantages of portability, low power consumption, and low radiation, and has been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras and the like. Furthermore, the LCD is considered by many to have the potential to completely replace CRT (cathode ray tube) monitors and televisions. 
     FIG. 3  is a schematic diagram of a typical LCD. The LCD  10  includes an LCD panel  11 , a backlight  12  for projecting light to the LCD panel  11 , and an LCD driving circuit  13 . The LCD panel  11  includes a display area  114  for displaying images, and a periphery circuit area  116 . The LCD driving circuit  13  includes a backlight driving circuit  17 , a panel driving circuit  18  positioned on the periphery circuit area  116 , a power supply device  16 , and a system control device  15 . 
   The power supply device  16  provides a voltage to drive the backlight driving circuit  17  and the panel driving circuit  18 . The system control device  15  provides a backlight driving signal to the backlight driving circuit  17 , and a control signal and a data signal to the panel driving circuit  18 . The panel driving circuit  18  drives the LCD panel  11  to display images on the display area  114  according to the control signal and the data signal. The backlight driving circuit  17  drives the backlight  12  according to the backlight driving signal. 
     FIG. 4  is a block diagram of the panel driving circuit  18 . The panel driving circuit  18  includes a gate driver  184 , a source driver  183 , a latch circuit  182 , a gamma adjustment and grayscale voltage generation circuit  187 , a regulator circuit  186 , a first booster circuit  185 , and a panel interface circuit  181 . The panel driving circuit  18  is an integrated circuit. 
   The first booster circuit  185  receives the voltage from the power supply device  16  and drives the gate driver  184  and the regulator circuit  186 . The regulator circuit  186  supplies driving voltages to the gate driver  184 , the source driver  183 , the latch circuit  182 , and the gamma adjustment and grayscale voltage generation circuit  187 . The panel interface circuit  181  receives the control signal and the data signal from the system control device  15 , and provides them to the gate driver  184 , the first booster circuit  185 , the regulator circuit  186 , the latch circuit  182 , and the gamma adjustment and grayscale voltage generation circuit  187 . The latch circuit  182  and the gamma adjustment and grayscale voltage generation circuit  187  are used to drive the source driver  183  according to the control signal and the data signal. The gate driver  184  is used to scan the LCD panel  11  according to the control signal and the data signal. The source driver  183  provides a plurality of grayscale voltages to the LCD panel  11  when the display area  114  is scanned by the gate driver  184 . 
     FIG. 5  is a block diagram of the backlight driving circuit  17 . The backlight driving circuit  17  includes a backlight interface circuit  171 , a second booster circuit  172 , and an analog/digital transform circuit  173 . 
   The second booster circuit  172  receives the voltage from the power supply device  16  and drives the analog/digital transform circuit  173 . The backlight interface circuit  171  receives the backlight driving signal from the system control device  15 , and provides it to the second booster circuit  172  and the analog/digital transform circuit  173 . The analog/digital transform circuit  173  is used to drive the backlight  12  according to the backlight driving signal. The backlight driving circuit  17  is an integrated circuit. 
   Because both the backlight driving circuit  17  and the panel driving circuit  18  include a booster circuit  172 ,  185  therein, the layout of conductive lines  161  that are used to supply the electrical power to the backlight driving circuit  17  and the panel driving circuit  18  from the power supply device  16  has a complicated configuration. Furthermore, because both the backlight driving circuit  17  and the panel driving circuit  18  include an interface circuit  171 ,  181  therein, the lay out of conductive lines  151  that are used to transmit signals also has a complicated configuration too. 
   It is desired to provide a driving circuit of an LCD which overcomes the above-described deficiencies. 
   SUMMARY 
   A driving circuit of an LCD includes a system driver, a power supply device device, and a system control device. The power supply device provides a votage to the system driver. The system control device generates a backlight driving signal, a data signal and a control signal and applies them to the system driver. The system driver drives an LCD panel and a backlight of the LCD according to the backlight driving signal, the data signal and the control signal. 
   An LCD includes an LCD panel, a backlight, and a driving circuit. The driving circuit includes a system driver, a power supply device, and a system control device. The power supply device provides a votage to the system driver. The system control device generates a backlight driving signal, a data signal and a control signal and applies them to the system driver. The system driver drives the LCD panel and the backlight of the LCD according to the backlight driving signal, the data signal and the control signal. 
   Advantages and novel features of the above-described circuit will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of an LCD having a driving circuit according to a preferred embodiment of the present invention. 
       FIG. 2  is a block diagram of a system driver of the driving circuit of  FIG. 1 , also showing a power supply device and a system control device of the driving circuit. 
       FIG. 3  is a schematic diagram of a conventional LCD having an LCD driving circuit. 
       FIG. 4  is a block diagram of a panel driving circuit of the LCD driving circuit of  FIG. 3 , also showing a power supply device and a system control device of the LCD driving circuit. 
       FIG. 5  is a block diagram of a backlight driving circuit of the LCD driving circuit of  FIG. 3 , also showing the power supply device and the system control device of the LCD driving circuit. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Reference will now be made to the drawings to describe the present invention in detail. 
     FIG. 1  is a schematic diagram of an LCD having a driving circuit according to a preferred embodiment of the present invention. The LCD  20  includes an LCD panel  21 , a backlight  22  for projecting light to the LCD panel  21 , and a driving circuit  23 . The LCD panel  21  includes a display area  214  for displaying images, and a periphery circuit area  216 . The driving circuit  23  includes a system driver  28 , a power supply device  26 , and a system control device  25 . The power supply device  26  provides a voltage to the system driver  28 . The system control device  25  provides a backlight driving signal, a data signal, and a control signal to the system driver  28 . The system driver  28  is positioned on the periphery circuit area  216  for driving the LCD panel  21  to display images on the display area  214  according to the backlight driving signal, the data signal and the control signal. The backlight  22  can be a light emitting diode (LED) or a cold cathode fluorescent lamp (CCLF). The system driver  28  can be an integrated circuit (IC). 
     FIG. 2  is a block diagram of the system driver  28 , also showing the power supply device  26  and the system control device  25 . The system driver  28  includes a gate driver  284 , a source driver  283 , a latch circuit  282 , a gamma adjustment and grayscale voltage generation circuit  287 , a regulator circuit  286 , a booster circuit  285 , an analog/digital transform circuit  288 , and a system interface circuit  281 . 
   The booster circuit  285  receives the voltage from the power supply device  26 , and drives the gate driver  284  and the regulator circuit  286 . The regulator circuit  286  supplies driving voltages to the gate driver  284 , the source driver  283 , the latch circuit  282 , the gamma adjustment and grayscale voltage generation circuit  287 , and the analog/digital transform circuit  288 . The system interface circuit  281  receives the control signal and data signal from the system control device  25 , and provides them to the gate driver  284 , the booster circuit  285 , the regulator circuit  286 , the latch circuit  282 , and the gamma adjustment and grayscale voltage generation circuit  287 . The system interface circuit  281  also receives the backlight driving signal from the system control device  25 , and provides it to the analog/digital transform circuit  288 . The latch circuit  282  and the gamma adjustment and grayscale voltage generation circuit  287  are used to drive the source driver  283  according to the control signal and the data signal. The gate driver  284  is used to scan the LCD panel  21  according to the control signal and the data signal. The source driver  283  provides a plurality of grayscale voltages to the LCD panel  21  when the LCD panel  21  is scanned by the gate driver  284 . The analog/digital transform circuit  288  is used to drive the backlight  22  according to the backlight driving signal. 
   Because the driving circuit  23  only has one booster circuit  285  and one system interface circuit  281 , the layout of conductive lines  251 ,  261  for supplying the electrical power and transmitting signals to the system driver  28  has a relatively simple configuration. 
   It is to be understood, however, that even though numerous characteristics and advantages of the preferred embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.