Liquid crystal display and method of fabricating the same

• US 20060126000A1
• Filed: 06/23/2005
• Published: 06/15/2006
• Est. Priority Date: 12/13/2004
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Choi, Su Seok, Choi, Sang Ho
• Granted Patent: US 8,059,255 B2
• Time in Patent Office: Days
• US Class Current: 349/172
• CPC Class Codes: G02F 1/133711 by organic films, e.g. polymeric films
• CPC Class Codes: G02F 1/133726 made of a mesogenic material
• CPC Class Codes: G02F 1/133788 by light irradiation, e.g. linearly polarised light photo-polymerisation

Abstract

A liquid crystal display device includes an upper substrate including an upper polarizer having a first light absorption axis and an upper electrode, a lower substrate including a lower polarizer having a second light absorption axis substantially parallel to the first light absorption axis and a lower electrode, a ferroelectric liquid crystal layer formed on at least one of the upper substrate and the lower substrate, and a nematic system liquid crystal layer formed on the ferroelectric liquid crystal layer between the upper substrate and the lower substrate.

Claims

1. A liquid crystal display device, comprising:

an upper substrate including an upper polarizer having a first light absorption axis and an upper electrode;

a lower substrate including a lower polarizer having a second light absorption axis substantially parallel to the first light absorption axis and a lower electrode;

a ferroelectric liquid crystal layer formed on at least one of the upper substrate and the lower substrate; and

a nematic system liquid crystal layer formed on the ferroelectric liquid crystal layer between the upper substrate and the lower substrate.

2. The liquid crystal display device according to claim 1, wherein the nematic system liquid crystal layer is substantially driven in-plane by the ferroelectric liquid crystal layer.

3. The liquid crystal display device according to claim 1, further comprising an alignment film formed on each of the upper substrate and the lower substrate.

4. The liquid crystal display device according to claim 3, wherein the ferroelectric liquid crystal layer is formed on the alignment film.

5. The liquid crystal display device according to claim 1, wherein the upper and lower electrodes are transparent electrodes.

6. The liquid crystal display device according to claim 1, wherein a first ferroelectric liquid crystal layer is formed on the upper substrate and a second ferroelectric liquid crystal layer is formed on the lower substrate.

7. The liquid crystal display device according to claim 6, wherein a spontaneous polarization direction of the first ferroelectric liquid crystal layer is opposite to a spontaneous polarization direction of the second ferroelectric liquid crystal layer.

8. The liquid crystal display device according to claim 1, wherein a spontaneous polarization direction of the ferroelectric liquid crystal layer is aligned towards the substrate on which it is formed.

9. The liquid crystal display device according to claim 1, wherein a spontaneous polarization direction of the ferroelectric liquid crystal layer is aligned towards the nematic system liquid crystal layer.

10. A fabricating method of a liquid crystal display device, comprising the steps of:

forming an upper polarizer having a first light absorption axis on an upper substrate;

forming a lower polarizer having a second light absorption axis on a lower substrate, the second light absorption axis being substantially parallel to the first light absorption axis;

forming an electrode on each of the upper substrate and the lower substrate;

forming a ferroelectric liquid crystal layer on at least one of the upper substrate and the lower substrate; and

forming a nematic system liquid crystal layer on the ferroelectric liquid crystal layer between the upper substrate and the lower substrate.

11. The fabricating method according to claim 10, further comprising the step of forming an alignment film in each of the upper substrate and the lower substrate.

12. The fabricating method according to claim 11, wherein the ferroelectric liquid crystal layer is formed on the alignment film.

13. The fabricating method according to claim 10, wherein the step of forming the ferroelectric liquid crystal layer includes the steps of:

forming a ferroelectric liquid crystal solution by mixing a ferroelectric liquid crystal into a solvent;

spreading the solution over at least one of the upper substrate and the lower substrate;

evaporating the solvent within the solution by heating the substrate; and

aligning a spontaneous polarization direction of the ferroelectric liquid crystal.

14. The fabricating method according to claim 13, wherein the solution includes between about 93 wt % and 97 wt % of the ferroelectric liquid crystal and between about 3 wt % and 7 wt % of the solvent.

15. The fabricating method according to claim 13, wherein the step of aligning the spontaneous polarization direction of the ferroelectric liquid crystal includes any one of a step of exposing the ferroelectric liquid crystal to a medium having high or low polarity, applying an electric field to the ferroelectric liquid crystal, and applying a magnetic field to the ferroelectric liquid crystal.

16. The fabricating method according to claim 10, wherein the step of forming the ferroelectric liquid crystal layer includes the steps of:

forming a ferroelectric liquid crystal solution by mixing a ferroelectric liquid crystal with a photopolymerization monomer;

spreading the solution over at least one of the upper substrate and the lower substrate;

aligning a spontaneous polarization direction of the ferroelectric liquid crystal; and

polymerizing the photopolymerization monomer by irradiating the solution with ultraviolet ray.

17. The fabricating method according to claim 16, wherein the solution includes between about 95 wt % and 99 wt % of the ferroelectric liquid crystal and between about 1 wt % and 5 wt % of the photopolymerization monomer.

18. The fabricating method according to claim 16, wherein the step of aligning the spontaneous polarization direction of the ferroelectric liquid crystal includes any one of a step of exposing the ferroelectric liquid crystal to a medium having high or low polarity, applying an electric field to the ferroelectric liquid crystal, and applying a magnetic field to the ferroelectric liquid crystal.

19. The fabricating method according to claim 10, wherein the step of forming the ferroelectric liquid crystal layer includes the step of:

forming a first ferroelectric liquid crystal layer on the upper substrate; and

forming a second ferroelectric liquid crystal layer on the lower substrate.

20. The fabricating method according to claim 19, further comprising the step of aligning a spontaneous polarization direction of the first ferroelectric liquid crystal layer opposite to a spontaneous polarization direction of the second ferroelectric liquid crystal layer.

21. The fabricating method according to claim 10, further comprising the step of aligning a spontaneous polarization direction of the ferroelectric liquid crystal layer towards the substrate on which it is formed.

22. The fabricating method according to claim 10, further comprising the step of aligning a spontaneous polarization direction of the ferroelectric liquid crystal layer towards the nematic system liquid crystal layer.