Liquid crystal display device and driving method

• US 20030053018A1
• Filed: 07/25/2002
• Published: 03/20/2003
• Est. Priority Date: 07/25/2001
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ono, Shinya
• Granted Patent: US 6,903,713 B2
• Time in Patent Office: Days
• US Class Current: 349/129
• CPC Class Codes: G02F 1/133738 for homogeneous alignment
• CPC Class Codes: G02F 1/133742 for homeotropic alignment
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]

Abstract

A liquid crystal panel includes a cell formed between substrates and disposed to face each other and severally including alignment films and, liquid crystal molecules held inside the cell, and an electrode for applying a driving electric field in a parallel direction to the liquid crystal molecules. In the liquid crystal panel, the electrode is formed on at least one of the substrates and on a side facing the liquid crystal molecules. An alignment film is formed on the substrate so as to cover the electrode and an alignment film is disposed on the opposite substrate. The alignment films and are severally selected from a horizontal alignment film and a perpendicular alignment film which are different in aligning modes.

Claims

1. A liquid crystal panel comprising:

a cell formed between substrates, the substrates being disposed to face each other and severally including alignment films;

liquid crystal molecules held in the cell; and

an electrode for applying a driving electric field in a direction parallel to a surface of the substrates,

wherein the electrode is formed on at least one of the substrates on a side facing the liquid crystal molecules, and

the alignment film disposed on the substrate to cover the electrode and the alignment film disposed on the opposite substrate are severally selected from a horizontal alignment film and a perpendicular alignment film which are mutually different in aligning modes.

2. The liquid crystal panel according to claim 1, wherein the electrode is composed of plural pairs of comb electrodes which form driving electric fields for driving the liquid crystal molecules.

3. The liquid crystal panel according to claim 1, wherein the perpendicular alignment film is disposed adjacently to the electrode.

4. The liquid crystal panel according to claim 1, wherein an alignment direction of the horizontal alignment film is set within 10 degrees with respect to the direction of the electric fields in a parallel direction generated by the comb electrodes.

5. The liquid crystal panel according to claim 1,

wherein a tilt angle of the horizontal alignment film is set in a range from 70 to 90 degrees with respect to a thickness direction of the cell, and

a tilt angle of the perpendicular alignment film is set in a range from 0 to 30 degrees with respect to the thickness direction of the cell.

6. The liquid crystal panel according to claim 1,

wherein an optical compensator is disposed on the liquid crystal panel adjacently to any one of the substrate where the comb electrodes are formed and the opposite substrate,

the optical compensator includes discotic liquid crystal molecules, and

the discotic crystal molecules are selected from horizontal alignment and perpendicular alignment which are different from each other severally on a side adjacent to the substrate and on a side facing the substrate.

7. The liquid crystal panel according to claim 1, wherein the liquid crystal molecules are nematic liquid crystal molecules.

8. A liquid crystal display device comprising:

a liquid crystal panel including

a cell formed between substrates which are disposed to face each other and severally include alignment films,

liquid crystal molecules held in the cell, and

an electrode for applying a driving electric field in a direction parallel to a surface of the substrates; and

a backlight unit,

wherein the electrode is formed on at least one of the substrates on a side facing the liquid crystal molecules, and

the alignment film disposed on the substrate to cover the electrode and the alignment film disposed on the opposite substrate are severally selected from a horizontal alignment film and a perpendicular alignment film which are mutually different in aligning modes.

9. The liquid crystal display device according to claim 8, wherein the electrode is composed of plural pairs of comb electrodes which form driving electric fields for driving the liquid crystal molecules.

10. The liquid crystal display device according to claim 8, wherein the perpendicular alignment film is disposed adjacently to the electrode.

11. The liquid crystal display device according to claim 8, wherein an alignment direction of the horizontal alignment film is set within 10 degrees with respect to the direction of the electric fields in a parallel direction generated by the comb electrodes.

12. The liquid crystal display device according to claim 8,

wherein a tilt angle of the horizontal alignment film is set in a range from 70 to 90 degrees with respect to a thickness direction of the cell, and

a tilt angle of the perpendicular alignment film is set in a range from 0 to 30 degrees with respect to the thickness direction of the cell.

13. The liquid crystal display device according to claim 8,

wherein an optical compensator is disposed on the liquid crystal panel on the opposite substrate, on any one of a side of adjacent to the liquid crystal molecules and an opposite face thereto,

the optical compensator includes discotic liquid crystal molecules, and

the discotic liquid crystal molecules are selected from horizontal alignment and perpendicular alignment which are different from each other severally on a side of the adjacent substrate and on a side facing to the substrate.

14. The liquid crystal display device according to claim 8, wherein the liquid crystal molecules are nematic liquid crystal molecules.

15. A driving method for a liquid crystal display device including a liquid crystal panel having a cell formed between substrates disposed to face each other and severally including alignment films, liquid crystal molecules held in the cell and an electrode for applying a driving electric field in a direction parallel to a surface of the substrates, and a backlight unit, the method comprising the steps of:

generating a parallel electric field by the electrode formed on at least one of the substrates and disposed on a side facing the liquid crystal molecules;

aligning the liquid crystal molecules by the parallel electric field;

transmitting a light beam from the backlight unit through the cell after polarizing the light beam; and

controlling the transmission of the light beam by applying and canceling the parallel electric field.

16. The driving method for a liquid crystal display device according to claim 15, wherein the step of transmitting the light beam through the cell includes a step of transmitting the polarized light beam through alignment films severally selected from a horizontal alignment film and a perpendicular alignment film of mutually different aligning modes.

17. The driving method for a liquid crystal display device according to claim 15, the method further comprising:

a step of generating the parallel electric field from plural pairs of comb electrodes for forming a driving voltage to drive the liquid crystal molecules.

18. The driving method for a liquid crystal display device according to claim 15, the method further comprising:

a step of generating the parallel electric field on a side of the perpendicular alignment film.

19. The driving method for a liquid crystal display device according to claim 15, the method further comprising:

a step of generating the parallel electric field within 10 degrees with respect to an alignment direction of the horizontal alignment film.

20. The driving method for a liquid crystal display device according to claim 15,

wherein a tilt angle of the horizontal alignment film is set in a range from 70 to 90 degrees with respect to a thickness direction of the cell, and

a tilt angle of the perpendicular alignment film is set in a range from 0 to 30 degrees with respect to the thickness direction of the cell.

21. The driving method for a liquid crystal display device according to claim 15,

wherein the step of transmitting the light beam includes a step of transmitting the light beam through an optical compensator, which is disposed adjacently to an opposite side to a side abutting on the liquid crystal molecules of the substrate facing to the substrate where the comb electrodes are formed,

the optical compensator includes discotic liquid crystal molecules, and

the discotic liquid crystal molecules are selected from horizontal alignment and perpendicular alignment which are different from each other on a side adjacent to the substrate and on a side facing the substrate.