Liquid crystal display device and method for manufacture of same

• US 20050136196A1
• Filed: 12/07/2004
• Published: 06/23/2005
• Est. Priority Date: 12/18/2003
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation, Fujitsu Display Technologies Corporation (Fujitsu Limited)
• Inventors: Kataoka, Shingo
• Granted Patent: US 7,767,108 B2
• Time in Patent Office: Days
• US Class Current: 428/1.100
• CPC Class Codes: C09K 19/32 containing condensed ring systems, i.e. fused, bridged or spiro ring systems
• CPC Class Codes: C09K 19/54 Additives having no specific mesophase characterised by their chemical composition
• 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: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133703 by introducing organic surfactant additives into the liquid crystal material
• CPC Class Codes: G02F 1/133742 for homeotropic alignment

Abstract

In a method for manufacture of a liquid crystal display device in which a liquid crystal composition is placed between two substrates, after which ultraviolet irradiation is performed to form a liquid crystal layer, a specific polymerizable compound is used, or specific ultraviolet irradiation conditions are adopted, or processing is comprised midway through the ultraviolet irradiation to activate the molecular motion of liquid crystal molecules or to deform the liquid crystal layer. A method for manufacture of a liquid crystal display device and a liquid crystal display device manufactured by this method are provided, in which an alignment control film is rendered unnecessary, and which has such advantages as improved quality of the liquid crystal panel, enhanced production yields, streamlined manufacturing facilities, simplified processes, and reduced costs.

Claims

1. A method for manufacture of a liquid crystal display device, in which a liquid crystal composition comprising liquid crystal molecules and a polymerizable compound which undergoes polymerization under the action of light or a combination of light and heat and which can align said liquid crystal molecules in the vertical direction, is placed between two substrates, after which ultraviolet irradiation is performed to polymerize the polymerizable compound, forming a liquid crystal layer;

wherein

ultraviolet irradiation under a first set of conditions, and ultraviolet irradiation under a second set of conditions for which the rate of polymerization is higher than for said first set of conditions, are combined and performed in this order.

2. The method for manufacture of a liquid crystal display device according to claim 1, wherein prior to ultraviolet irradiation under said first set of conditions, or between ultraviolet irradiation under said first set of conditions and ultraviolet irradiation under said second set of conditions, ultraviolet irradiation is performed under a third set of conditions for which the polymerization rate is lower than for said first set of conditions.

3. The method for manufacture of a liquid crystal display device according to claim 1, wherein conditions of said ultraviolet irradiation relating to the polymerization rate are determined in terms of ultraviolet radiation wavelength, or ultraviolet radiation intensity, or temperature, or a combination thereof.

19. The method for manufacture of a liquid crystal display device according to claim 1, wherein

said liquid crystal composition comprises a compound having the structure of the following formula (2):

(where Y is an acrylate group or a methacrylate group, A is an aromatic ring which may have a substituent, an alicyclic ring which may have a substituent, or a group of an aliphatic chain which may have branches, and n is an integer of 0 or

     1).

23. The method for manufacture of a liquid crystal display device according to claim 19, wherein n=0.

24. The method for manufacture of a liquid crystal display device according to claim 1, wherein the distances between spacers determining the distance between said substrates are maintained at values equal to or greater than a prescribed value.

28. The method for manufacture of a liquid crystal display device according to claim 24, wherein protruding structures provided on a substrate are used as said spacers.

29. The method for manufacture of a liquid crystal display device according to claim 1, wherein said liquid crystal molecules have a negative dielectric constant anisotropy, and have the properties of being aligned substantially vertically when no voltage is applied, and being inclined, when a voltage is applied, in directions regulated by protrusions formed on the substrate or by slits in electrodes.

30. A liquid crystal display device, manufactured by a method for manufacture of a liquid crystal display device according to claim 1.

31. A liquid crystal display device, manufactured by a method for manufacture of a liquid crystal display device according to claim 29.

4. A method for manufacture of a liquid crystal display device, in which a liquid crystal composition comprising liquid crystal molecules and a polymerizable compound which undergoes polymerization under the action of light or a combination of light and heat and which can align said liquid crystal molecules in the vertical direction, is placed between two substrates, after which ultraviolet irradiation is performed to polymerize the polymerizable compound, forming a liquid crystal layer, comprising:

processing to activate the molecular motion of the liquid crystal molecules midway through said ultraviolet irradiation.

5. The method for manufacture of a liquid crystal display device according to claim 4, wherein said activation processing is heating of the liquid crystal layer to the vicinity of a phase transition point of said liquid crystal molecules from a liquid crystal state to an isotropic state.

10. The method for manufacture of a liquid crystal display device according to claim 4, wherein

ultraviolet irradiation under a first set of conditions, and ultraviolet irradiation under a second set of conditions for which the rate of polymerization is higher than for said first set of conditions, are combined and performed in this order.

13. The method for manufacture of a liquid crystal display device according to claim 10, wherein prior to ultraviolet irradiation under said first set of conditions, or between ultraviolet irradiation under said first set of conditions and ultraviolet irradiation under said second set of conditions, ultraviolet irradiation is performed under a third set of conditions for which the polymerization rate is lower than for said first set of conditions.

14. The method for manufacture of a liquid crystal display device according to claim 10, wherein conditions of said ultraviolet irradiation relating to the polymerization rate are determined in terms of ultraviolet radiation wavelength, or ultraviolet radiation intensity, or temperature, or a combination thereof.

20. The method for manufacture of a liquid crystal display device according to claim 4, wherein

said liquid crystal composition comprises a compound having the structure of the following formula (2):

(where Y is an acrylate group or a methacrylate group, A is an aromatic ring which may have a substituent, an alicyclic ring which may have a substituent, or a group of an aliphatic chain which may have branches, and n is an integer of 0 or

     1).

25. The method for manufacture of a liquid crystal display device according to claim 4, wherein the distances between spacers determining the distance between said substrates are maintained at values equal to or greater than a prescribed value.

32. The method for manufacture of a liquid crystal display device according to claim 4, wherein said liquid crystal molecules have a negative dielectric constant anisotropy, and have the properties of being aligned substantially vertically when no voltage is applied, and being inclined, when a voltage is applied, in directions regulated by protrusions formed on the substrate or by slits in electrodes.

6. A method for manufacture of a liquid crystal display device, in which a liquid crystal composition comprising liquid crystal molecules and a polymerizable compound which undergoes polymerization under the action of light or a combination of light and heat and which can align said liquid crystal molecules in the vertical direction, is placed between two substrates, after which ultraviolet irradiation is performed to polymerize the polymerizable compound, forming a liquid crystal layer, comprising:

processing to deform said liquid crystal layer midway through said ultraviolet irradiation.

11. The method for manufacture of a liquid crystal display device according to claim 6, wherein

ultraviolet irradiation under a first set of conditions, and ultraviolet irradiation under a second set of conditions for which the rate of polymerization is higher than for said first set of conditions, are combined and performed in this order.

15. The method for manufacture of a liquid crystal display device according to claim 6, comprising:

processing to activate the molecular motion of the liquid crystal molecules midway through said ultraviolet irradiation.

17. The method for manufacture of a liquid crystal display device according to claim 15, wherein said activation processing is heating of the liquid crystal layer to the vicinity of a phase transition point of said liquid crystal molecules from a liquid crystal state to an isotropic state.

21. The method for manufacture of a liquid crystal display device according to claim 6, wherein

said liquid crystal composition comprises a compound having the structure of the following formula (2):

(where Y is an acrylate group or a methacrylate group, A is an aromatic ring which may have a substituent, an alicyclic ring which may have a substituent, or a group of an aliphatic chain which may have branches, and n is an integer of 0 or

     1).

26. The method for manufacture of a liquid crystal display device according to claim 6, wherein the distances between spacers determining the distance between said substrates are maintained at values equal to or greater than a prescribed value.

33. The method for manufacture of a liquid crystal display device according to claim 6, wherein said liquid crystal molecules have a negative dielectric constant anisotropy, and have the properties of being aligned substantially vertically when no voltage is applied, and being inclined, when a voltage is applied, in directions regulated by protrusions formed on the substrate or by slits in electrodes.

7. A method for manufacture of a liquid crystal display device, in which a liquid crystal composition comprising liquid crystal molecules and a polymerizable compound which undergoes polymerization under the action of light or a combination of light and heat and which can align said liquid crystal molecules in the vertical direction, is placed between two substrates, after which ultraviolet irradiation is performed to polymerize the polymerizable compound, forming a liquid crystal layer;

wherein

said liquid crystal composition comprises a compound having the structure of the following formula (1);

(where X is an acrylate group or a methacrylate group;

R is an alkyl group or an alkoxy group, with the number of carbon atoms between 1 and 18, or one of these groups with a portion of the carbon atoms or hydrogen atoms replaced by other atoms or molecules;

a is 0 or 1; and

m is an integer between 0 and

     2).

8. The method for manufacture of a liquid crystal display device according to claim 7, wherein a=0.

9. The method for manufacture of a liquid crystal display device according to claim 8, wherein m=0.

12. The method for manufacture of a liquid crystal display device according to claim 7, wherein

ultraviolet irradiation under a first set of conditions, and ultraviolet irradiation tinder a second set of conditions for which the rate of polymerization is higher than for said first set of conditions, are combined and performed in this order.

16. The method for manufacture of a liquid crystal display device according to claim 7, comprising:

processing to activate the molecular motion of the liquid crystal molecules midway through said ultraviolet irradiation.

18. The method for manufacture of a liquid crystal display device according to claim 7, comprising:

processing to deform said liquid crystal layer midway through said ultraviolet irradiation.

22. The method for manufacture of a liquid crystal display device according to claim 7, wherein

said liquid crystal composition comprises a compound having the structure of the following formula (2):

(where Y is an acrylate group or a methacrylate group, A is an aromatic ring which may have a substituent, an alicyclic ring which may have a substituent, or a group of an aliphatic chain which may have branches, and n is an integer of 0 or

     1).

27. The method for manufacture of a liquid crystal display device according to claim 7, wherein the distances between spacers determining the distance between said substrates are maintained at values equal to or greater than a prescribed value.

34. The method for manufacture of a liquid crystal display device according to claim 7, wherein said liquid crystal molecules have a negative dielectric constant anisotropy, and have the properties of being aligned substantially vertically when no voltage is applied, and being inclined, when a voltage is applied, in directions regulated by protrusions formed on the substrate or by slits in electrodes.