Patent Publication Number: US-8531440-B2

Title: Column driver device, driving device, and related serial transmission device for a liquid crystal display device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a column driver device, a driving device and a related serial transmission device for a liquid crystal display device, and more particularly, to a column driver device, a driving device and a related serial transmission device for reducing instantaneous current for enhancing reliability of the devices by averaging the effect resulting from signal level change of the devices according to different coding schemes. 
     2. Description of the Prior Art 
     With the advancement of display technology, the size of a panel in a liquid crystal display (LCD) device is getting larger to meet demands, which results in an increase in the number of pixels in the panel and heavy loading of data transmission. For this reason, a prior art serial transmission device provides a solution to improve the above problem. 
     Please refer to  FIG. 1 .  FIG. 1  is a schematic diagram of a driving device  10  in an LCD device according to the prior art. The driving device  10  is a serial transmission device, which comprises a timing controller  102  and source drivers, also called column drivers, SD_ 1  to SD_n. The timing controller  102  is utilized for performing signal processes for outputting displaying data to a source driver SD_ 1 . The source drivers SD_ 1  to SD_n are in series for outputting data line signals to data line groups DLS_ 1  to DLS_n on the panel, wherein each data line group comprises at least one data line. Now describe the operation of the source drivers SD_ 1  to SD_n. The source driver SD_ 1  receives data corresponding to a data line group DLS_ 1  from the displaying data outputted from the timing controller  102 , performs related processes on the received data for generating results, and outputs the results to the data line group DLS_ 1 . Meanwhile, the source driver SD_ 1  transfers the displaying data outputted from the timing controller  102  to a source driver SD_ 2 . The source driver SD_ 2  performs processes similar to the source driver SD_ 1  and then transfers the displaying data to a source driver SD_ 3 , and so forth. As a result, the driving device  10  outputs the displaying data to the data line groups DLS_ 1  to DLS_n on the panel for displaying a frame. 
     However, when signal level of the displaying data changes, for example the displaying data changes from 0 to 1 or from 1 to 0, the current consumption of the driving device  10  increases. The signal level change results in a large instantaneous current that may lead to abnormal voltage rise/drop or a temperature rise, so as to result in a state transfer failure or abnormal displaying, moreover, a reliability problem of the driving device  10 . 
     SUMMARY OF THE INVENTION 
     It is therefore a primary objective of the claimed invention to provide a column driving device, a driving device and related serial transmission device for a liquid crystal display (LCD) device. 
     The present invention discloses a serial transmission device for reducing instantaneous current comprising an input terminal for receiving serial data, a coding module coupled to the input terminal comprising a plurality of coding units in series for transforming the serial data to a plurality of coding results according to a plurality of coding schemes, and a plurality of output terminals respectively coupled to the plurality of coding units of the coding module for outputting the plurality of coding results. 
     The present invention further discloses a column driving device for an LCD device comprising a serial data generator coupled to a timing controller of the LCD device for transforming parallel data to serial data, a coding module coupled to the serial data generator comprising a plurality of coding units in series for transforming the serial data to a plurality of coding results according to a plurality of coding schemes, a latch module coupled to the coding module for storing the plurality of coding results, and a decoding module coupled to the latch module for performing decoding processes on the plurality of coding results for generating a plurality of column driving signals according to the plurality of coding schemes. 
     The present invention further discloses a driving device for an LCD device comprising a timing controller for generating displaying data, a column driver module coupled to the timing controller comprising a plurality of column drivers in series for outputting the displaying data according to a plurality of coding schemes, wherein each column driver of the column driver module comprises an input terminal for receiving the displaying data, a coding unit coupled to the input terminal for transforming the displaying data to a coding result according to one of the plurality of coding schemes, a processing unit coupled to the coding unit for performing a signal process on the displaying data for generating a column driving signal, and an output terminal coupled to the coding unit for outputting the coding result to another column driver, and a display module coupled to the column driver module for displaying the displaying data according to a plurality of column driving signals outputted by the column driver module. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a driving device in an LCD device according to the prior art. 
         FIG. 2  is a schematic diagram of a serial transmission device according to an embodiment of the present invention. 
         FIG. 3  is a schematic diagram of a column driving device in an LCD device according to an embodiment of the present invention. 
         FIG. 4  is a schematic diagram of a column driving device in an LCD device according to an embodiment of the present invention. 
         FIG. 5  is a schematic diagram of a column driving device in an LCD device according to an embodiment of the present invention. 
         FIG. 6  is a code table of binary code and Gray code. 
         FIG. 7  is a schematic diagram of implementation of Gray code. 
         FIG. 8  is a schematic diagram of a binary decoder. 
         FIG. 9  is a schematic diagram of a Gray decoder. 
         FIG. 10  is a schematic diagram of a driving device in an LCD device according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 2 .  FIG. 2  is a schematic diagram of a serial transmission device  20  according to an embodiment of the present invention. The serial transmission device  20  is utilized for reducing instantaneous current and comprises an input terminal  202 , a coding module  204  and output terminals OP_ 1  to OP_n. The input terminal  202  is utilized for receiving serial data. The coding module  204  is coupled to the input terminal  202  and comprises coding units C_ 1  to C_n in series for transforming the serial data to coding results according to different coding schemes. The output terminals OP_ 1  to OP_n are respectively coupled to coding units C_ 1  to C_n for outputting the coding results. In detail, a coding unit C_ 1  performs a coding process on the serial data received by the input terminal  202  for generating a coding result, outputs the coding result via an output terminal OP_ 1  and at the same time, and transfers the coding result to a coding unit C_ 2 . Next, the coding unit C_ 2  performs another coding process on the received coding result, outputs another coding result via an output terminal OP_ 2 , and transfers the another coding result to a coding unit C_ 3 , and so forth. As a result, the serial transmission device  20  outputs different coding results via the output terminals OP_ 1  to OP_n. 
     The serial data can be transformed to different coding results by different coding schemes. For example, if “01” is the original serial data, “00”, “01”, “10” or “11” is possible to be the coding result from different coding schemes. In other words, a data transfer state changes by different coding schemes. Therefore, compared to the serial data received by the input terminal  202 , there may only a part of the coding results of the coding units C_ 1  to C_n with data transfer states. That is, the serial transmission device  20  can stagger data transfer states to prevent from increase of instantaneous current caused by signal level change. 
     Note that, the serial transmission device  20  is an embodiment of the present invention, and those skilled in the art can make alterations and modifications accordingly. For example, in the serial transmission device  20  the input terminal  202  can also be coupled to a parallel-to-serial converter utilized for transforming parallel data to the serial data first. In addition, the input terminal  202  can be coupled between any two coding units, for example, coding unit C_ 1  and C_ 2 , or coupled to all of the coding units C_ 1  to C_n instead of being coupled to the nearest coding unit C_ 1 , as shown in  FIG. 2 . Moreover, the number of the coding units is dependent on demands and the coding scheme corresponding to each coding unit can be any kind of code scheme, such as binary code, Gray code, Hamming code, Turbo code, and etc. 
     In a word, the serial transmission device  20  reduces instantaneous current by averaging the effect resulting from signal level change of the devices according to serial transmission and different coding schemes, so as to enhance reliability of the serial transmission device  20 . 
     From the above, the serial transmission device  20  can reduce instantaneous current by averaging the effect resulting from signal level change of the devices for enhancing reliability of the serial transmission device  20 . Note that, the present invention can be applied in any kind of device or system using serial transmission. Please refer to  FIG. 3 .  FIG. 3  is a schematic diagram of a column driving device  30  in an LCD device according to an embodiment of the present invention. The column driving device  30  comprises a serial data generator  302 , a coding module  304 , a latch module  306  and a decoding module  308 . The serial data generator  302  is coupled to a timing controller  310  of the LCD device for transforming parallel data to serial data. The coding module  304  is coupled to the serial data generator  302  and comprises coding units C_ 1  to C_n in series for transforming the serial data to coding results according to different coding schemes. The latch module  306  is coupled to the coding module  304  for storing the coding results in latches L 1  and L 2 . The decoding module  308  is coupled to the latch module  306  and comprises decoders D_ 1  to D_n for performing decoding processes on the coding results stored in the latch module  306  for generating corresponding column driving signals according to different coding schemes. 
     From the above, the serial data can be transformed to different coding results by different coding schemes. Therefore, compared to the original serial data outputted from the serial data generator  302 , there may only a part of the coding results of the coding units C_ 1  to C_n with data transfer states. That is, the coding module  304  can stagger data transfer states to prevent from increase of instantaneous current caused by signal level change. 
     Note that, the column driving device  30  is an embodiment of the present invention, and those skilled in the art can make alterations and modifications accordingly. For example, the serial data generator  302  can be coupled between any two coding units, for example, coding unit C_ 1  and C_ 2 , or coupled to all of the coding units C_ 1  to C_n instead of being coupled to the nearest coding unit C_ 1 , as shown in  FIG. 3 . Moreover, the number of the coding units is dependent on demands and the coding scheme corresponding to each coding unit can be any kind of code scheme, such as binary code, Gray code, Hamming code, Turbo code, and etc. 
     In addition, please refer to  FIG. 4 .  FIG. 4  is a schematic diagram of a column driving device  40  in an LCD device according to an embodiment of the present invention. The column driving device  40  comprises a serial data generator  402 , coding units  404  and  406 , a latch module  410  and a decoding module  412 . The structure of the column driving device  40  is similar to the column driving device  30  and is not given here. The difference is, the column driving device  40  only comprises two coding units and the serial data generator  402  is coupled between the coding unit  404  and the coding unit  406 . In this situation, the decoding module  412  comprises only two decoders, DAC 1  and DAC 2 , corresponding to two different coding schemes, so as to reducing complexity and production cost. Therefore, according to the column driving device  40 , the coding units  404  and  406  can stagger data transfer states to prevent from increase of instantaneous current caused by signal level change. 
     Moreover, please refer to  FIG. 5 .  FIG. 5  is a schematic diagram of a column driving device  50  in an LCD device according to an embodiment of the present invention. The column driving device  50  comprises a serial data generator  502 , coding units  504  and  506 , a latch module  510  and a decoding module  512 . The structure of the column driving device  50  is similar to the column driving device  40  and is not given here. The difference is, the serial data generator  502  is only coupled to the coding unit  504 . Similarly, the column driving device  50  can stagger data transfer states to prevent from increase of instantaneous current caused by digital signal level change. 
     The column driving device  40  and the column driving device  50  are embodiments of the present invention, which can stagger data transfer states according to two different coding schemes, and those skilled in the art can make alterations and modifications accordingly. For example, the corresponding coding schemes are not limited to specific coding schemes. For example, please refer to  FIG. 6  for a code table of binary code and Gray code. As shown in  FIG. 6 , when 0 transfers to 7, the corresponding binary code transfers from 000 to 111 and the corresponding Gray code transfers from 000 to 100. That is, there are 3 data transfer states for using binary code and only 1 data transfer state for using Gray code, and the combination of binary code and Gray code can average the number of data transfer states to 2. Therefore, the column driving device  40  and the column driving device  50 , which use the combination of binary code and Gray code, can reduce the number of data transfer states for reducing instantaneous current for preventing from overheat. 
     Please refer to  FIG. 7  for a schematic diagram of implementation of Gray code. Binary code transfers to Gray code by an exclusive-OR logic circuit. Please refer to  FIG. 8  and  FIG. 9  for implementation of decoders DAC 1  and DAC 2 .  FIG. 8  is a schematic diagram of a binary decoder  80 .  FIG. 9  is a schematic diagram of a Gray decoder  90 . In  FIG. 8  and  FIG. 9 , V 1  to V 8  represent 8 different voltage signals corresponding to 8 signal levels, 0 to 7. Switches D 1  and D 1 B respectively control to output 1 and 0 for the most significant bit (MSB), switches D 2  and D 2 B respectively control to output 1 and 0 for the second bit, and switches D 3  and D 3 B respectively control to output 1 and 0 for the least significant bit (LSB). Therefore, the binary decoder  80  and the Gray decoder  90  can output correct signals according to ON/OFF state of these six switches. For example, if the received data is “100”, the binary decoder  80  outputs a voltage signal V 5  and the Gray decoder  90  outputs a voltage signal V 8 . Please note that  FIG. 8  and  FIG. 9  are examples of decoders, and other coding schemes and decoders also can be applied in the present invention. 
     From the above, the present invention can be applied in any kind of device or system using serial transmission for reducing instantaneous current by averaging the effect resulting from signal level change. Please refer to  FIG. 10 .  FIG. 10  is a schematic diagram of a driving device  100  in an LCD device according to an embodiment of the present invention. The driving device  100  comprises a timing controller  1002 , a column driver module  1004  and a display module  1006 . The timing controller  1002  is utilized for generating displaying data. The column driver module  1004  is coupled to the timing controller  1002  and comprises column drivers C 10 _ 1  to C 10 _n in series for outputting the displaying data according to different coding schemes. In each column driver of the column driver module  1004 , a coding unit is utilized for transforming the displaying data to coding results according to a corresponding coding scheme and outputting the coding results to another column driver, and a processing unit is utilized for performing signal processes on the displaying data for generating column driving signals. Therefore, in the driving device  100 , each column driver can perform a coding process on the displaying data according to a corresponding coding scheme. The displaying data can be transformed to different coding results by different coding schemes. Compared to the displaying data, there may only a part of the coding results of the column driver C 10 _ 1  to C 10 _n with data transfer states. That is, the column driver C 10 _ 1  to C 10 _n can stagger data transfer states to prevent from increase of instantaneous current caused by signal level change, so as to avoid abnormal frame displaying caused by rising temperatures. 
     Note that, the driving device  100  is an embodiment of the present invention, and those skilled in the art can make alterations and modifications accordingly. For example, in  FIG. 10 , the timing controller  1002  also can be coupled between any two column drivers, such as a column driver C 10 _ 1  and a column driver C 10 _ 2 , or coupled to all of the column drivers. 
     In conclusion, the present invention can perform serial transmission according to different coding schemes for staggering data transfer states in a column driver for reducing instantaneous current caused by signal level change, so as to enhance the reliability. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.