LIQUID CRYSTAL DISPLAY AND DRIVING METHOD THEREOF

• US 20090322974A1
• Filed: 03/24/2009
• Published: 12/31/2009
• Est. Priority Date: 06/25/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Sung-Woon, Lee, Seung-Hoon, Lu, Jiangang, Kim, Hee-Seop, Yeom, Joo-Seok
• Granted Patent: US 8,593,583 B2
• Time in Patent Office: Days
• US Class Current: 349/37
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence

Abstract

The present invention relates to a liquid crystal display including: a first substrate, a gate line formed disposed on the first substrate, a first data line and a second data lines formed both of which are disposed on the first substrate, and insulated from and intersection disposed substantially perpendicular to the gate line, a first thin film transistor connected to the gate line and the first data line, a second thin film transistor connected to the gate line and the second data line, a first pixel electrode connected to the first thin film transistor, a second pixel electrode connected to the second thin film transistor, a second substrate facing disposed substantially opposite to the first substrate, a common electrode formed disposed on the second substrate, and a liquid crystal layer disposed between the first substrate and the second substrate, and including biaxial liquid crystal.

Claims

1. A liquid crystal display comprising:

a first substrate;

a gate line disposed on the first substrate;

a first data line and a second data line both of which are disposed on the first substrate, and insulated from and disposed substantially perpendicular to the gate line;

a first thin film transistor connected to the gate line and the first data line;

a second thin film transistor connected to the gate line and the second data line;

a first pixel electrode connected to the first thin film transistor;

a second pixel electrode connected to the second thin film transistor;

a second substrate disposed substantially opposite to the first substrate;

a common electrode disposed on the second substrate; and

a liquid crystal layer disposed between the first substrate and the second substrate, and including biaxial liquid crystal.

2. The liquid crystal display of claim 1, wherein

the first pixel electrode and the second pixel electrode respectively include a first stem and a second stem, and a plurality of first branches and second branches respectively connected to the first stem and the second stem.

3. The liquid crystal display of claim 2, wherein the first branches and the second branches are alternately disposed with respect to each other.

4. The liquid crystal display of claim 3, wherein the first stem and second stem are disposed substantially parallel to the gate line, or the first data line and the second data line, and

the first branches and the second branches are disposed substantially perpendicular to the first stem and the second stem.

5. The liquid crystal display of claim 4, wherein the first pixel electrode and the second pixel electrode respectively further include a first connection and a second connection for connection with the first thin film transistor and the second thin film transistor, respectively.

6. The liquid crystal display of claim 3, wherein the branches are curved at a predetermined angle.

7. The liquid crystal display of claim 1, wherein the first pixel electrode and the second pixel electrode are configured to include a period in which substantially the same voltage is applied thereto and a period in which a different voltage is applied thereto during one frame.

8. The liquid crystal display of claim 1, wherein the biaxial liquid crystal has different refractive indexes and different dielectric ratios in x-, y-, and z-axis directions, and an axis direction having a maximum refractive index and an axial direction having a maximum dielectric ratio are different from each other.

9. The liquid crystal display of claim 1, wherein the biaxial liquid crystal has different refractive indexes and different dielectric ratios in x-, y-, and z-axis directions, and an axis direction having a maximum refractive index and an axial direction having a maximum dielectric ratio are substantially the same.

10. The liquid crystal display of claim 1, wherein the rubbing direction for the biaxial liquid crystal is oblique to the gate line and the first data line and the second data line.

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

polarizers attached to the outside surface of the first substrate and the second substrate,

wherein the transmittance directions of the polarizers are oblique to the gate line and the first data line and second data line.

12. A driving method for a liquid crystal display including first and second thin film transistors connected to a single gate line, and first and second data lines, first and second pixel electrodes respectively connected to the first and second thin film transistors, a common electrode disposed substantially opposite to the first and second pixel electrodes, and a biaxial liquid crystal layer, the driving method comprising:

applying a gate-on voltage to the gate line;

applying a first data voltage to the first data line; and

applying a second data voltage to the second data line,

wherein the applying of the second data voltage divides one frame into at least two periods including a first period wherein a voltage with substantially the same polarity and magnitude as the first data voltage is applied to the second data line as the second data voltage, and a second period wherein a voltage with a different polarity and magnitude from the first data voltage is applied to the second data line as the second data voltage.

13. The driving method of claim 12, wherein the first period begins again after the second period has passed at the end of one frame, and the first period and the second period are alternately applied.

14. The driving method of claim 12, wherein the second data voltage applied during the second period is substantially the same voltage as that applied to the common electrode.

15. The driving method of claim 12, wherein the second data voltage applied in the second period has substantially the same magnitude as the first data voltage and the opposite polarity to that of the first data voltage.

16. The driving method of claim 12, wherein the length of the first period is greater than the length of the second period for one frame.

17. The driving method of claim 12, further comprising:

applying a voltage to the common electrode,

wherein the common electrode is applied with the common voltage during the first period, and the common electrode is electrically connected to a floating ground potential in the second period.

18. A driving method of a liquid crystal display including a biaxial liquid crystal, comprising:

applying a horizontal electric field to the biaxial liquid crystal;

pre-tilting the biaxial liquid crystal using the horizontal electric field; and

applying a vertical electric field to the biaxial liquid crystal after pre-tilting the biaxial liquid crystal.

19. The driving method of claim 18, wherein the horizontal electric field and the vertical electric field are alternately applied in one frame.

20. The driving method of claim 18, wherein a black gray level is displayed before applying the horizontal electric field.

21. The driving method of claim 18, wherein a gray level is displayed by controlling the vertical electric field in the applying of the vertical electric field.

22. The driving method of claim 18, wherein the applying of the horizontal electric field and the applying of the vertical electric field are alternately executed.