Abstract:
Data transmission circuit with ESD protection comprises a first set of data lines and a second set of data lines; a first set of ESD protection components coupled to the first set of data lines; a second set of ESD protection components coupled to the second set of data lines; a first current path coupled to the first set of ESD protection components for dispensing the ESD current; and a second current path coupled to the second set of ESD protection components for dispensing the ESD current.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a data transmission circuit with electrostatic discharge(ESD) protection, and more particularly, to a data transmission circuit with ESD protection in a liquid crystal display(LCD) 
         [0003]    2. Description of the Prior Art 
         [0004]    Please refer to  FIG. 1 .  FIG. 1  is a diagram illustrating a conventional LCD  100 . The LCD  100  comprises a data transmission circuit  110  and a pixel driving circuit  120 . The pixel driving circuit  120  comprises scan lines G 1  to Gm for transmitting pixel driving signals to pixels. The data transmission circuit  110  comprises data lines D 0  to Dn, ESD protection components E 0  to En, and a current path P 1 . In the data transmission circuit  110 , the data lines D 0  to Dn transmit frame data to the pixels; each of the ESD components E 0  to En has one end coupled to a corresponding data line, and the other end coupled to the current path P 1  for protecting the corresponding data line from damage by ESD events, and dispersing the ESD currents by lead the ESD currents to the current path P 1 . 
         [0005]    Please refer to  FIG. 2 .  FIG. 2  is a diagram illustrating data lines D 0  and D 1 . The data transmission circuit  110  transmits data of different polarities compared to the common voltage Vcom. And the polarities of data on different data lines can be the same or different. For example, the data transmission circuit  110  transmits data of positive polarity compared to the common voltage Vcom on the odd data lines D 0 , D 2 , D 4  . . . , and Dn× 1 . The data transmission circuit  110  transmits data of negative polarity compared to the common voltage Vcom on the even data lines D 1 , D 3 , D 5  . . . , and Dn. As shown in  FIG. 2 , the data line D 0  transmits data of positive voltages, and the data line D 1  transmits data of negative voltages. Thus, assumed that the corresponding voltage of data has a range from 0 to 5 volts, the voltage difference between the data lines D 0  and D 1  can be up to 10 volts as the voltage difference V×1 shown in  FIG. 2 . However, the behavior of the data transmission circuit  110  can be different with the description above. The data transmission circuit  110  can be defined to work in other manner. For example, the data transmission circuit  110  transmits data of negative polarity compared to the common voltage Vcom on the even data lines D 0 , D 2 , D 4  . . . , and Dn− 1 . The data transmission circuit  110  transmits data of positive polarity compared to the common voltage Vcom on the odd data lines D 1 , D 3 , D 5  . . . , and Dn. Or, the data transmission circuit  110  transmits data of negative polarity compared to the common voltage Vcom on the even data lines D 0 , D 2 , D 4  . . . , and Dn− 1  in a first period, and transmits data of positive polarity compared to the common voltage Vcom on the even data lines D 0 , D 2 , D 4  . . . , and Dn− 1  in a second period. Therefore, the voltage of a data line can be positive in a period and negative in other period. 
         [0006]    Please refer to  FIG. 3 .  FIG. 3  is a diagram illustrating the data lines D 0  and D 1 . When the data transmission circuit  110  transmits data, the voltages the data lines D 0  and D 1  are positive compared to the common voltage Vcom in one period, and are negative compared to the common voltage Vcom in another period. As shown in  FIG. 3 , the dotted line represents the voltage of the data line D 0 , and the solid line represents the voltage of the data line D 1 . It is assumed that the voltage corresponding to data ranges from 0 to 5 volts. Therefore, the voltage difference between the data lines D 0  and D 1  may be up to 10 volts, as the voltage difference V×2 shown in  FIG. 3 . 
         [0007]    There are too many examples about the driving method of the data lines to describe. Thus, the present invention provides some examples in order to illustrate that the data lines are driven by voltages of different polarities so that the voltage difference between data lines possibly may be over a ceiling. 
         [0008]    Please refer to  FIG. 4 .  FIG. 4  is a diagram illustrating the current flowing from the data line D 0  to the data line D 1  when there is a voltage difference between the data lines D 0  and D 1 . In fact, the ESD protection component is not ideal, and leaks current when a voltage is applied to the ESD protection component. The size of the leakage current rises as the voltage applied to the ESD protection component rises. Under the assumption that the voltage corresponding to data ranges from 0 to 5 volts, if all the data lines transmit data with voltages of the same polarity, the voltage difference between any of the two data lines is only up to 5 volts. But, if the data lines are driven by the method illustrated in  FIG. 2  or  FIG. 3 , the voltage difference between any of the two data lines may be over 5 volts. Consequently, even no ESD event happens, the ESD component still leaks current from the data line D 0  to the data line D 1  through the ESD component E 0  and the current path P 1 . In this way, the voltage levels of the data lines D 0  and D 1  are affected, causing wrong voltages to be transmitted to the pixels and wrong frames to be displayed (causing attenuated voltages to be transmitted to the pixels and affect display quality. The leak current also increases the undesired power consumption of driving circuit.) 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides a data transmission circuit with ESD protection. The data transmission circuit comprises a first set of data lines for receiving and transmitting data of a first type; a second set of data line for receiving and transmitting data of a second type; a first set of ESD protection components, each ESD protection component of the first set of the ESD protection components coupled to a corresponding data line of the first set of data lines; a second set of ESD protection components, each ESD protection component of the second set of the ESD protection components coupled to a corresponding data line of the second set of data lines; a first current path coupled to each ESD protection component of the first set of the ESD protection components; and a second current path coupled to each ESD protection component of the second set of the ESD protection components. 
         [0010]    The present invention provides a LCD having data transmission circuit with ESD protection. The LCD comprises a first glass substrate comprising a pixel driving circuit comprising a plurality of scan lines for transmitting a plurality of driving signals; a data transmission circuit comprising a first set of data lines for receiving and transmitting data of a first type; a second set of data line for receiving and transmitting data of a second type; a first set of ESD protection components, each ESD protection component of the first set of the ESD protection components coupled to a corresponding data line of the first set of data lines; a second set of ESD protection components, each ESD protection component of the second set of the ESD protection components coupled to a corresponding data line of the second set of data lines; a first current path coupled to each ESD protection component of the first set of the ESD protection components; and a second current path coupled to each ESD protection component of the second set of the ESD protection components; a plurality of first pixel areas wherein each first pixel area is coupled to the pixel driving circuit and a corresponding data line of the first set of the data lines for receiving a corresponding driving signals of the plurality of driving signals and a corresponding data of the data of the first type; and a plurality of second pixel areas wherein each second pixel area is coupled to the pixel driving circuit and a corresponding data line of the second set of the data lines for receiving a corresponding driving signals of the plurality of driving signals and a corresponding data of the data of the second type; and a second glass substrate; and a liquid crystal layer disposed between the first glass substrate and the second glass substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a diagram illustrating a conventional LCD. 
           [0012]      FIG. 2  is a diagram illustrating data lines. 
           [0013]      FIG. 3  is a diagram illustrating the data lines. 
           [0014]      FIG. 4  is a diagram illustrating the current flowing from one data line to another data line when there is a voltage difference between the data lines. 
           [0015]      FIG. 5  is a diagram illustrating the data transmission circuit of the present invention. 
           [0016]      FIG. 6  is a diagram illustrating a first embodiment of the ESD protection component En of the present invention. 
           [0017]      FIG. 7  is a diagram illustrating the second embodiment of the ESD protection component En of the present invention. 
           [0018]      FIG. 8  is a diagram illustrating a third embodiment of the ESD protection component En of the present invention. 
           [0019]      FIG. 9  is a diagram illustrating a fourth embodiment of the ESD protection component En of the present invention. 
           [0020]      FIG. 10  is a diagram illustrating a LCD of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Please refer to  FIG. 5 .  FIG. 5  is a diagram illustrating the data transmission circuit  500  of the present invention. As shown in  FIG. 5 , the data transmission circuit  500  comprises data lines D 0 , D 1 , D 2 , . . . , and Dn, ESD protection components E 0 , E 1 , E 2 , . . . , and En, and current paths P 2  and P 3 . It is assumed that the voltages of the even data lines D 0 , D 2 , D 4 , . . . , and Dn− 1  are positive, the voltages of the odd data lines D 1 , D 3 , D 5 , . . . , and Dn are negative, and the voltage range is also 5 volts. The present invention utilizes the character of the driving method of the data lines described above to design the transmission circuit  500 : dividing the ESD components E 0 -En into two groups, coupling each group to the corresponding data lines and current paths. As shown in  FIG. 5 , one ends of the even ESD protection components E 0 , E 2 , E 4 , . . . , and En are respectively coupled to the corresponding data lines D 0 , D 2 , D 4 , . . . , and Dn, and the other ends of the even ESD protection components E 0 , E 2 , E 4 , . . . , and En− 1  are conjointly coupled to the current path P 2 . One ends of the odd ESD protection components E 1 , E 3 , E 5 , . . . , and En are respectively coupled to the corresponding data lines D 1 , D 3 , D 5 , . . . , and Dn, and the other ends of the odd ESD protection components E 1 , E 3 , E 5 , . . . , and En are conjointly coupled to the current path P 3 . In this way, since the voltages of the even data lines D 0 , D 2 , D 4 , . . . , and Dn− 1  are all positive and ranges in 5 volts, the voltage over each ESD components E 0 , E 2 , E 4 , . . . , and En− 1  is not over 5 volts and no leakage current is generated if there is no ESD event. On the other hand, since the voltages of the odd data lines D 1 , D 3 , D 5 , . . . , and Dn are all negative and ranges in 5 volts, the voltage over each ESD components E 1 , E 3 , E 5 , . . . , and En is not over 5 volts and no leakage current is generated if there is no ESD event. Thus, the data transmission circuit  500  avoids current leakage caused by the voltage difference between two data lines over a ceiling. 
         [0022]    However, it is only an example of the present invention to divide the ESD protection components into two groups in the data transmission circuit  500 . The spirit of the present invention is to categorize the data lines by the voltages, and to couple the data lines of the same category to the same group of the ESD protection components and the current paths. In this way, the ESD protection components do not leak current caused by the voltage difference between the data lines of the same group. Thus, in reality, it is also possible to divide the ESD protection components and the current paths into more groups to prevent the ESD protection components from conducting when no ESD events happen. 
         [0023]    Please refer to  FIG. 6 .  FIG. 6  is a diagram illustrating a first embodiment of the ESD protection component En of the present invention. As shown in  FIG. 6 , the ESD protection component En comprises two diodes Da and Db. The diode Da is reversely coupled to the diode Db. 
         [0024]    Please refer to  FIG. 7 .  FIG. 7  is a diagram illustrating the second embodiment of the ESD protection component En of the present invention. As shown in  FIG. 7 , the ESD protection component En comprises 4 diodes Dc, Dd, De, and Df. A first back-to-back diode is composed of the diode Dc reversely coupled to the diode Dd. A second back-to-back diode is composed of the diode De reversely coupled to the diode Df. The first back-to-back diode is coupled to the second back-to-back diode in parallel. 
         [0025]    Please refer to  FIG. 8 .  FIG. 8  is a diagram illustrating a third embodiment of the ESD protection component En of the present invention. As shown in  FIG. 8 , the ESD protection component En comprises two diodes Dg and Dh. The diode Dg is reversely coupled to the diode Dh in series. 
         [0026]    Please refer to  FIG. 9 .  FIG. 9  is a diagram illustrating a fourth embodiment of the ESD protection component En of the present invention. As shown in  FIG. 9 , the ESD component En comprises two Metal Oxide Semiconductor(MOS) transistors Qa and Qb. The gate of the MOS transistor Qa is coupled to the data line, the first end of the MOS transistor Qa is coupled to the data line, and the second end of the MOS transistor Qa is coupled to the current path. The gate of the MOS transistor Qb is coupled to the current path, the first end of the MOS transistor Qb is coupled to the current path, and the second end of the MOS transistor Qb is coupled to the data line. 
         [0027]    Please refer to  FIG. 10 .  FIG. 10  is a diagram illustrating a LCD  1000  of the present invention. The LCD  1000  comprises a first glass substrate  1100 , a liquid crystal layer  1200 , and a second glass substrate  1300 . The liquid crystal layer is disposed between the first and the second glass substrates  1100  and  1300 . The first glass substrate  1100  comprises a data transmission circuit  1110  and the pixel driving circuit  1120 . The data transmission circuit  1110  is composed as the same as the data transmission circuit  500  in  FIG. 5 . The pixel driving circuit  1120  is composed as the same as the pixel driving circuit  120 . The data lines D 0 -Dn of the data transmission circuit  1110  interweave the scan lines of the pixel driving circuit  1120  and the plurality of the pixels A 00 , A 01 , A 02 , . . . , and Anm− 1  are generated. The related description is the same as those described above and is omitted. Therefore, the LCD  1000  of the present invention avoids the ESD protection components conducting when no ESD events happen, which raises the display quality. 
         [0028]    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. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.