Liquid crystal display device having an overdriving data generator and method of driving the same

1. A liquid crystal display device, comprising:

an over driving data generator comparing a gray level of a data signal of a present frame with a gray level of a data signal of a previous frame to output an over driving data signal, wherein the data signal has a bit number of n to form 2 n gray levels of data signal, and the over driving data signal has a level number of 2 n +2, wherein a 1 st level of the over driving data signal is for over driving a 1 st gray level of data signal, 2 nd to (2 n +1) th levels of the over driving data signal are for over driving 2 nd to (2 n −1) th gray levels of data signal, and a (2 n +2) th level of the over driving data signal is for over driving a (2 n ) th gray level of data signal;

a gate driver that supplies a gate voltage to a gate line;

a (n+1)-bit data drive IC receiving the over driving data signal, and generating level voltages having a number of 2 n+1 such that (2 n +2) level voltages, among the 2 n+1 level voltages, corresponding to the 2 n +2 levels of the over driving data signal are used as over driving data voltages to be outputted to a data line;

a data processing circuit that generates a (n+k)-bit extended frame data signal;

a dithering circuit that is between the data processing circuit and the over driving data generator, the dithering circuit truncates k low significant bits of the extended frame data signal, and generates a plurality of n-bit frame data signals to spatially or temporally compensate the truncation of the k low significant bits, the plurality of n-bit frame data signals being repeated during at least one frame, the n-bit frame data being input to the over driving data generator,

wherein the 2 n+1 level voltages are divided into first, second and third level groups in level order such that the second level group has 2 n level voltages between the first and third level groups, the first level group has 2 n−1 level voltages, and the third level group has 2 n−1 level voltages, wherein one of the 2 n−1 level voltages of the first level group is used as an over driving data voltage corresponding to the (2 n +2) th level of the over driving data signal, wherein one of the 2 n−1 level voltages of the third level group is used as an over driving data voltage corresponding to the 1 st level of the over driving data signal, and wherein the 2 n level voltages of the second group are used as available gray level voltages corresponding to the 2 n gray levels of data signal and are used as over driving data voltages corresponding to the 2 nd to (2 n +1) th levels of the over driving data signal; and

a liquid crystal panel including a data line, a gate line and a pixel connected to the gate line and the data line, wherein the pixel is applied with the over driving data voltage corresponding to the over driving data signal through the data line.

2. The liquid crystal display device according to claim 1 , wherein the over driving data generator includes a frame memory storing the data signal of the previous frame.

3. The liquid crystal display device according to claim 1 , wherein the data processing circuit processes and outputs a source data signal to the dithering circuit.

4. The liquid crystal display device according to claim 1 , wherein the third level group includes gray level voltages from 1st to (2 (n−1) th level voltages- and having a number of 2 (n−1) , the second level group includes gray level voltages starting from (2 (n−1) +1)th level voltage and having a number of 2 n , and the first level group includes the remaining gray level voltages and having a number of 2 (n−1) .

5. The liquid crystal display device according to claim 1 , wherein n is 9.

6. A method of driving a liquid crystal display device, comprising:

comparing a gray level of a data signal of a present frame with a gray level of a data signal of a previous frame to output an over driving data signal using an over driving data generator, wherein the data signal has a bit number of n to form 2 n gray levels of data signal, and the over driving data signal has a level number of 2 n +2, wherein a 1 st level of the over driving data signal is for over driving a 1 st gray level of data signal, 2 nd to (2 n +1) th levels of the over driving data signal are for over driving 2 nd to (2n−1) th gray levels of data signal, and a (2 n +2) th level of the over driving data signal is for over driving a (2 n ) th gray level of data signal;

supplying a gate voltage to a gate line from a gate driver;

outputting the over driving data signal to a (n+1)-bit data drive IC, and generating level voltages having a number of (2 n +1) in the (n+1)-bit data drive IC such that 2 n +2 level voltages, among the 2 n+1 level voltages, corresponding to the 2 n +2 levels of the over driving data signal are used as over driving data voltages to be outputted to a data line from the (n+1)-bit data drive IC;

applying the over driving data voltage corresponding to the over driving data signal to a pixel, which is connected to the gate line and the data line, of a liquid crystal panel through the data line;

generating, by a data processing circuit, a (n+k)-bit extended frame data signal; and

performing a dithering process using a dithering circuit that is between the processing circuit and the over driving data generator, wherein the dithering circuit truncates k low significant bits of the extended frame data signal, and generates a plurality of n-bit frame data signals to spatially or temporally compensate the truncation of the k low significant bits, the plurality of n-bit frame data signals being repeated during at least one frame, the n-bit frame data being input to the over driving data generator,

wherein the 2 n+1 level voltages are divided into first, second and third level groups in level order such that the second level group has 2 n level voltages between the first and third level groups, the first level group has 2 n−1 level voltages, and the third level group has 2 n−1 level voltages, wherein one of the 2 n−1 level voltages of the first level group is used as an over driving data voltage corresponding to the (2 n +2) th level of the over driving data signal, wherein one of the 2 n−1 level voltages of the third level group is used as an over driving data voltage corresponding to the 1 st level of the over driving data signal, and wherein the 2 n level voltages of the second group are used as available gray level voltages corresponding to the 2 n gray levels of data signal and are used as over driving data voltages corresponding to the 2 nd to (2 n +1) th levels of the over driving data signal.

7. The method according to claim 6 , further comprising storing the data signal of the previous frame.

8. The method according to claim 6 , wherein the data processing circuit processes and outputs a source data signal to the dithering circuit.

9. The method according to claim 6 , wherein n is 9.