LIQUID CRYSTAL DISPLAY AND DRIVING METHOD THEREOF

• US 20090190052A1
• Filed: 10/01/2008
• Published: 07/30/2009
• Est. Priority Date: 01/29/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Jung, Mee-Hye, Jung, Kwang-Chul
• Granted Patent: US 8,570,265 B2
• Time in Patent Office: Days
• US Class Current: 349/38
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2300/0447 for multi-domain technique to improve the viewing angle in a liquid crystal display, such as multi-vertical alignment [MVA]
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display includes a first gate line transmitting a first gate signal, a first data line transmitting a first data voltage, and a first pixel connected to the first gate line and the first data line and including a first subpixel and a second subpixel. The first subpixel includes a first switching element connected to the first gate line, a first liquid crystal capacitor connected to the first switching element, and a first storage capacitor having a first terminal and a second terminal. The second subpixel includes a second switching element connected to the first gate line and the first data line, a second liquid crystal capacitor connected to the second switching element, and a second storage capacitor having a first terminal and a second terminal and having a capacitance different from a capacitance of the first storage capacitor. The first terminal of the first storage capacitor is connected to the first switching element, the first terminal of the second storage capacitor is connected to the second switching element, and the second terminal of the first storage capacitor and the second terminal of the second storage capacitor are coupled to each other and have a varying voltage thereof.

Claims

1. A liquid crystal display comprising:

a first gate line transmitting a first gate signal;

a first data line transmitting a first data voltage; and

a first pixel connected to the first gate line and the first data line and including a first subpixel and a second subpixel, wherein

the first subpixel comprises a first switching element connected to the first gate line, a first liquid crystal capacitor connected to the first switching element, and a first storage capacitor having a first terminal and a second terminal,

the second subpixel comprises a second switching element connected to the first gate line and the first data line, a second liquid crystal capacitor connected to the second switching element, and a second storage capacitor having a first terminal and a second terminal and having a capacitance different from a capacitance of the first storage capacitor,

the first terminal of the first storage capacitor is connected to the first switching element,

the first terminal of the second storage capacitor is connected to the second switching element, and

the second terminal of the first storage capacitor and the second terminal of the second storage capacitor are coupled to each other and have a varying voltage.

2. The liquid crystal display of claim 1, wherein the voltage of the second terminals of the first and second storage capacitors

is fixed while the first and second switching elements turn on to charge the first and second liquid crystal capacitors and the first and second storage capacitors, and

varies after the charging of the first and second storage capacitors is finished.

3. The liquid crystal display of claim 2, wherein the voltage of the second terminals of the first and second storage capacitors

rises when the voltage stored in the first and second liquid crystal capacitors and the first and second storage capacitors has a positive polarity, and

drops when the voltage stored in the first and second liquid crystal capacitors and the first and second storage capacitors has a negative polarity.

4. The liquid crystal display of claim 3, wherein the second terminal of the first and second storage capacitors is supplied with an external voltage.

5. The liquid crystal display of claim 4, further comprising a first storage electrode line that has a periodically varying voltage and is connected to the second terminals of the first and second storage capacitors.

6. The liquid crystal display of claim 5, further comprising:

a second storage electrode line that has a voltage having a polarity opposite a polarity of the voltage of the first storage electrode line;

a second data line transmitting a second data voltage; and

a second pixel connected to the first gate line and the second data line and comprising a third subpixel and a fourth subpixel,

wherein the third subpixel comprises a third switching element connected to the first gate line and the second data line, a third liquid crystal capacitor connected to the third switching element, and a third storage capacitor connected between the third switching element and the second storage electrode line, and

the fourth subpixel comprises a fourth switching element connected to the first gate line and the second data line, a fourth liquid crystal capacitor connected to the fourth switching element, and a fourth storage capacitor connected between the fourth switching element and the second storage electrode line and having a capacitance different from a capacitance of the third storage capacitor.

7. The liquid crystal display of claim 3, wherein the second terminals of the first and second storage capacitors alternate between a voltage-biased state and a floating state.

8. The liquid crystal display of claim 7, further comprising:

a first storage electrode line having a first voltage;

a second storage electrode line having a second voltage that is different from the first voltage; and

a second gate line transmitting the second gate signal,

wherein the first pixel further comprises

a third switching element connected to the first gate line, the first storage electrode line, and the second terminals of the first and second storage capacitors, and

a fourth switching element connected to the second gate line, the second storage electrode line, and the second terminals of the first and second storage capacitors.

9. The liquid crystal display of claim 8, wherein the third switching element transfers the first voltage while the first and second liquid crystal capacitors and the first and second storage capacitors are charged, and

the fourth switching element is turned on to transfer the second voltage after the third switching element is turned off.

10. The liquid crystal display of claim 9, further comprising:

a third gate line transmitting a third gate signal; and

a second pixel connected to the second and third gate lines and the first data line and comprising a third subpixel, a fourth subpixel, a fifth switching element, and a sixth switching element,

wherein the fifth switching element is connected to the second gate line and the second storage electrode line,

the sixth switching element is connected to the third gate line and the first storage electrode line,

the third subpixel comprises a seventh switching element connected to the second gate line and the first data line, a third liquid crystal capacitor connected to the seventh switching element, and a third storage capacitor connected between the fifth switching element and the seventh switching element, and

the fourth subpixel comprises an eighth switching element connected to the second gate line and the first data line, a fourth liquid crystal capacitor connected to the eighth switching element, and a fourth storage capacitor connected between the sixth switching element and the eighth switching element and having a capacitance different from a capacitance of the third storage capacitor.

11. The liquid crystal device of claim 10, wherein the fifth switching element transfers the second voltage while the third and fourth liquid crystal capacitors and the third and fourth storage capacitors are charged, and

the sixth switching element turns on to transfer the first voltage after the fifth switching element is turned off.

12. The liquid crystal device of claim 11, wherein voltages of the first, second, and third gate lines vary sequentially.

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

charging first and second liquid crystal capacitors and first and second storage capacitors with substantially the same voltage;

floating first terminals of the first liquid crystal capacitor and the first storage capacitor that are connected to each other, and first terminals of the second liquid crystal capacitor and the second storage capacitor that are connected to each other; and

changing voltages of the second terminals of the first and second storage capacitors by substantially the same level to cause voltages of the first terminal of the first liquid crystal capacitor and the first terminal of the second liquid crystal capacitor to be differentiated.

14. The driving method of claim 13, wherein a capacitance of the first storage capacitor is different from a capacitance of the second storage capacitor.

15. The driving method of claim 14, wherein during the charging, the voltages of the second terminals of the first and second storage capacitors are maintained at fixed values.

16. The driving method of claim 15, wherein the changing voltages comprises:

raising the voltages of the second terminals of the first and second storage capacitors when the first and second liquid crystal capacitors and the first and second storage capacitors are charged with a positive voltage, and

lowering the voltages of the second terminals of the first and second storage capacitors when the first and second liquid crystal capacitors and the first and second storage capacitors are charged with a negative voltage.

17. The driving method of claim 16, further comprising:

applying an external voltage to the second terminals of the first and second storage capacitors constantly.

18. The driving method of claim 16, further comprising:

floating the second terminals of the first and second storage capacitors after changing the voltages.