LIQUID CRYSTAL DISPLAY DEVICE, METHOD OF MANUFACTURING THE SAME AND ALIGNMENT LAYER COMPOSITION FOR THE LIQUID CRYSTAL DISPLAY DEVICE

• US 20100182556A1
• Filed: 01/07/2010
• Published: 07/22/2010
• Est. Priority Date: 01/19/2009
• Status: Active Grant

• Current Assignee: TCL China Star Optoelectronics Technology Co. Ltd. (TCL Technology Group Corp.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Oh, Keun-Chan, Lyu, Jae-Jin, Cho, Seon-Ah, Sohn, Ji-Won
• Granted Patent: US 8,962,107 B2
• Time in Patent Office: Days
• US Class Current: 349/127
• CPC Class Codes: C09K 19/56 Aligning agents
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/027 Polyimide
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/133723 Polyimide, polyamide-imide
• 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
• CPC Class Codes: H01J 9/205 Applying optical coatings or shielding coatings to the vessel of flat panel displays, e.g. applying filter layers, electromagnetic interference shielding layers, anti-reflection coatings or anti-glare coatings
• CPC Class Codes: H01J 9/233 Manufacture of photoelectric screens or charge-storage screens

Abstract

A liquid crystal display device that includes an array substrate, an opposite substrate and a liquid crystal display layer is described. The array substrate includes a pixel electrode and a lower alignment layer. The pixel electrode has a plurality of slit portions extending in different directions. The lower alignment layer includes a reactive mesogen (RM) diamine is formed on the pixel electrode to induce an alignment direction of the liquid crystal molecules. An upper alignment layer is formed on a common electrode of the opposite substrate. The RM is cured at surfaces of the lower and upper alignment layers in response to ultraviolet (UV) light, so that liquid crystal molecules have a pretilt angle. Therefore, the aperture ratio and the response time may be improved, and afterimages may be decreased, so that display quality may be improved.

Claims

1. A liquid crystal display (LCD) device comprising:

an array substrate including;

a lower substrate having a switching part formed thereon;

a pixel electrode formed on a unit pixel area defined on the lower substrate to connect with the switching part, the pixel electrode having a plurality of slit portions extending in different directions; and

a lower alignment layer formed on the pixel electrode, the lower alignment layer including a reactive mesogen (RM) to induce an alignment direction of liquid crystal molecules;

an opposite substrate including an upper substrate opposite to the lower substrate, a common electrode formed on the upper substrate to face the pixel electrode, and an upper alignment layer formed on the common electrode; and

a liquid crystal layer comprising liquid crystal molecules having a pretilt angle between a surface of the lower alignment layer and a surface of the upper alignment layer.

2. The LCD device of claim 1, wherein the upper alignment layer comprises an RM to induce an alignment direction of liquid crystal molecules.

3. The LCD device of claim 2, wherein the lower alignment layer and the upper alignment layer include a polyimide, and are formed from an alignment layer composition including a base dianhydride, a base diamine, a crosslinker, a vertical alignment diamine and an RM diamine, the content of the RM diamine being about 10 wt % to about 80 wt % based on a total weight of the base diamine, the vertical alignment diamine and the RM diamine.

4. The LCD device of claim 2, wherein the pixel electrode comprises a first pixel electrode and a second pixel electrode that are disposed on the unit pixel area to receive the different pixel voltages, and the slit portions are formed on a plurality of domains defined on the first and second pixels.

5. The LCD device of claim 4, wherein the common electrode corresponding to the first and second pixel electrodes has a continuous shape and does not include an opening.

6. The LCD device of claim 2, wherein the lower alignment layer and the upper alignment layer are configured to arrange a long axis of the liquid crystal molecules in a vertical direction when an electric field is not applied to the liquid crystal layer.

7. The LCD device of claim 2, wherein the lower alignment layer and the upper alignment layer are configured to arrange a long axis of the liquid crystal molecules in an extending direction of the slit portion at each of the domains when an electric field is applied to the liquid crystal layer.

8. The LCD device of claim 3, wherein the alignment layer composition further comprises an initiator having substantially the same structure as the RM.

9. The LCD device of claim 2, wherein the liquid crystal layer further comprises an additional RM, which is no more than about 0.3 wt %.

10. The LCD device of claim 3, wherein the RM diamine includes a compound represented by:

wherein Y represents at least one selected from the group consisting of an acrylate group, a methacrylate group, a vinyl group, a vinyloxy group and/or an epoxy group;

X₂ represents an alkyl group, an alkenyl group, and/or an alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring;

A₂ represents an alkenyl group, and/or an alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring, wherein each hydrogen atom is replaceable with a functional group;

X₁ represents an alkyl group, an alkenyl group, and/or an alkynyl group, which have 1 to 18 carbon atoms and have a chain or ring structure including at least one ring or condensed ring, —

COO—

, —

OCO—

, —

O—

or —

CONH— and

;

A₁ represents an alkenyl group, an alkenyl group, and/or an alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring, wherein each hydrogen atom is replaceable with a functional group.

11. A method of manufacturing an LCD device, the method comprising:

forming a lower alignment layer on an array substrate comprising a pixel electrode having a plurality of slit portions inducing an alignment direction of liquid crystal molecules, the lower alignment layer including an RM;

coupling an opposite substrate to the array substrate;

providing a liquid crystal layer between the lower alignment layer and the array substrate; and

irradiating the lower alignment layer with light under conditions in which an electric field is applied to the liquid crystal layer through the pixel electrode to provide a pretilt angle to liquid crystal molecules at a surface of the lower alignment layer.

12. The method of claim 11, further comprising:

forming an upper alignment layer on a common electrode of the opposite substrate before coupling the opposite substrate to the array substrate.

13. The method of claim 12, wherein the upper alignment layer includes an RM.

14. The method of claim 12, wherein the common electrode corresponding to the pixel electrode has a continuous shape and does not include an opening.

15. The method of claim 12, wherein the lower alignment layer and the upper alignment layer include a polyimide, formed from an alignment layer composition including a base dianhydride, a base diamine, a crosslinker, a vertical alignment diamine and an RM diamine, the content of the RM diamine being about 10 wt % to about 80 wt % based on a total weight of the base diamine, the vertical alignment diamine and the RM diamine.

16. The method of claim 15, wherein the RM diamine includes a compound represented by:

wherein Y represents at least one selected from the group consisting of an acrylate group, a methacrylate group, a vinyl group, a vinyloxy group and/or an epoxy group;

X₂ represents an alkyl group, an alkenyl group, and/or an alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring;

A₂ represents an alkenyl group, and/or alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring, wherein each hydrogen atom is replaceable with a functional group;

X₁ represents an alkyl group, an alkenyl group, and/or an alkynyl group, which have 1 to 18 carbon atoms and have a chain or ring structure including at least one ring or condensed ring, —

COO—

, —

OCO—

, —

O—

or —

CONH— and

;

A₁ represents an alkenyl group, an alkenyl group, and/or an alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring, wherein each hydrogen atom is replaceable with a functional group.

17. The method of claim 11, wherein the liquid crystal layer includes an additional RM, which is no more than about 0.3 wt %.

18. The method of claim 15, wherein the alignment layer composition further comprises an initiator having the same structure as the RM diamine.

19. The method of claim 11, wherein the pixel electrodes are formed on a unit pixel area of the array substrate, and the slit portions are extended in different directions on a plurality of domains defined on each of the pixel electrodes.

20. The method of claim 19, wherein the lower alignment and the upper alignment layer are configured so that a long axis of the liquid crystal molecules is vertically aligned when an electric field is not applied to the liquid crystal layer.

21. The method of claim 19, wherein the lower alignment layer and the upper alignment layer are configured so that the long axis of the liquid crystal molecules is arranged in an extending direction of the slit portion at each of the domains when an electric field is applied to the liquid crystal layer.

22. An alignment layer composition for an LCD device, the alignment layer composition comprising:

a base anhydride;

a base diamine;

a crosslinker; and

a side chain component.

23. The alignment layer composition of claim 22, wherein the base anhydride includes a base dianhydride.

24. The alignment layer composition of claim 22, wherein the side chain component includes a vertical alignment diamine and an RM diamine.

25. The alignment layer composition of claim 24, wherein a content of the RM diamine is about 10 wt % to about 80 wt % based on a total weight of the base diamine, the vertical alignment diamine and the RM diamine.

26. The alignment layer composition of claim 24, wherein the RM diamine includes a compound represented by:

wherein Y represents at least one selected from the group consisting of an acrylate group, a methacrylate group, a vinyl group, a vinyloxy group and/or an epoxy group;

X₂ represents an alkyl group, an alkenyl group, and/or an alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring;

A₂ represents an alkenyl group, and/or alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring, wherein each hydrogen atom is replaceable with a functional group;

X₁ represents an alkyl group, an alkenyl group, and/or an alkynyl group, which have 1 to 18 carbon atoms and have a chain structure or a ring structure including at least one ring or condensed ring, —

COO—

, —

OCO—

, —

O—

or —

CONH— and

;

A₁ represents an alkenyl group, an alkenyl group, and/or an alkynyl group having 1 to 18 carbon atoms and having a chain or ring structure including at least one ring or condensed ring, wherein each hydrogen atom is replaceable with a functional group.