Dual data driving mode liquid crystal display

1. A display device having a display panel in which a plurality of gate lines and a plurality of data lines cross each other to define a plurality of pixels, the display panel comprising:

a timing control unit that outputs a first data control signal and an image data;

a first data driving unit on a first side of the display panel that generates a first data signal from the image data according to the first data control signal, outputs the first data signal to one of the plurality of data lines from the first side, and generates a second data control signal from the first data control signal; and

a second data driving unit on a second side of the display panel that generates a second data signal from the first data signal according to the second data control signal, the second data signal substantially synchronized with the first data signal, and outputs the second data signal to the one of the plurality of data lines from the second side,

wherein the second data driving unit comprises:

a reference voltage generating unit that generates a first reference voltage and a second reference voltage having different levels from the first data signal; and

a switching unit that outputs one of the first reference voltage and the second reference voltage as the second data signal according to the second data control signal.

2. The display device of claim 1 , wherein the first reference voltage and the second reference voltage each are generated to have a magnitude smaller than that of the first data signal.

3. The display device of claim 1 , wherein the second data control signal includes a polarity control signal, and

the switching unit alternately outputs the first reference voltage and the second reference voltage during 1 period of the polarity control signal.

4. The display device of claim 3 , wherein the switching unit outputs the second data signal synchronized with the first data signal according to the polarity control signal.

5. The display device of claim 1 , wherein the second data control signal includes a polarity control signal and a charge control signal, and

the switching unit comprises:

a first switching transistor that is turned on during a first section of the polarity control signal to output the first reference voltage;

a second switching transistor that is turned on during a second section of the polarity control signal to output the second reference voltage; and

a third switching transistor that is turned on according to the charge control signal during the first section of the polarity control signal to output the first reference voltage as the second data signal, and that is turned on according to the charge control signal during the second section of the polarity control signal to output the second reference voltage as the second data signal.

6. The display device of claim 1 , wherein the second data control signal includes a charge control signal, and

the second data driving unit varies a magnitude of the second data signal by adjusting a duty ratio of the charge control signal.

7. The display device of claim 1 , wherein the display panel is a liquid crystal display panel.

8. A display device having a display panel in which a plurality of gate lines and a plurality of data lines cross each other to define a plurality of pixels, the display panel comprising:

a timing control unit that outputs a first data control signal and an image data;

a first data driving unit on a first side of the display panel that generates a first data signal from the image data according to the first data control signal, outputs the first data signal to one of the plurality of data lines from the first side, and generates a second data control signal from the first data control signal; and

a second data driving unit on a second side of the display panel that generates a second data signal from the first data signal according to the second data control signal, the second data signal substantially synchronized with the first data signal, and outputs the second data signal to the one of the plurality of data lines from the second side,

wherein the second data driving unit comprises:

a reference voltage generating unit that generates first to fourth reference voltages having different levels from the first data signal; and

a switching unit that combines two of the first to fourth reference voltages according to the second data control signal and outputs the two combined reference voltage as the second data signal.

9. The display device of claim 8 , wherein the second data control signal includes a polarity control signal, a select signal, and a charge control signal, and

the switching unit comprises:

a first switching transistor and a third switching transistor that are turned on during a first section of the polarity control signal to output the first reference voltage and the third reference voltage, respectively;

a second switching transistor and a fourth switching transistor that are turned on during a second section of the polarity control signal to output the second reference voltage and the fourth reference voltage, respectively;

a fifth switching transistor that is turned on during a first section of the select signal to output one of the first reference voltage and the third reference voltage;

a sixth switching transistor that is turned on during a second section of the select signal to output one of the second reference voltage and the fourth reference voltage; and

a seventh switching transistor that is turned on according to the charge control signal during a first section of the polarity control signal to output one of the first reference voltage and the third reference voltage as the second data signal, and that is turned on according to the charge control signal during a second section of the polarity control signal to output one of the second reference voltage and the fourth reference voltage as the second data signal.