Liquid crystal display device and method for manufacture of same

• US 7,767,108 B2
• Filed: 12/07/2004
• Issued: 08/03/2010
• Est. Priority Date: 12/18/2003
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation, Fujitsu Limited
• Inventors: Kataoka, Shingo
• Primary Examiner(s): Visconti; Geraldina
• Application Number:
  US11/006,250
• Publication Number:
  US 20050136196A1
• Time in Patent Office: 2,065 Days
• Field of Search: 252/299.01, 252/299.6, 430/20, 428/1.1, 349/1, 349/187
• US Class Current: 252/299.01
• 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, thus forming a liquid crystal layer, wherein:

said ultraviolet irradiation comprises a first ultraviolet irradiation stage and a second ultraviolet irradiation stage after the first ultraviolet irradiation stage; and

the rate of polymerization in the second ultraviolet irradiation stage is higher than the rate of polymerization in the first ultraviolet irradiation stage.

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

3. The method for manufacture of a liquid crystal display device according to claim 1, wherein conditions of said stages of 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.

18. 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):

22. The method for manufacture of a liquid crystal display device according to claim 18, wherein n=0.

23. 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.

27. The method for manufacture of a liquid crystal display device according to claim 23, wherein protruding structures provided on a substrate are used as said spacers.

28. The method for manufacture of a liquid crystal display device according to claims 1 through 27, 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.

29. A liquid crystal display device, manufactured by a method for manufacture of a liquid crystal display device according to any of claims 1 through 27.

30. A liquid crystal display device, manufactured by a method for manufacture of a liquid crystal display device according to claim 28.

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, thus forming a liquid crystal layer, comprising:

heating the liquid crystal layer to a vicinity of a phase transition point of said liquid crystal molecules from a liquid crystal state to an isotropic state midway through said ultraviolet irradiation.

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

said ultraviolet irradiation comprises a first ultraviolet irradiation stage and a second ultraviolet irradiation stage after the first ultraviolet irradiation stage; and

the rate of polymerization in the second ultraviolet irradiation stage is higher than the rate of polymerization in the first ultraviolet irradiation stage.

12. The method for manufacture of a liquid crystal display device according to claim 9, wherein prior to said first ultraviolet irradiation stage, or between said first and second ultraviolet irradiation stages, a third ultraviolet irradiation stage is performed in which the polymerization rate is lower than for the polymerization rate in said first ultraviolet irradiation stage.

13. The method for manufacture of a liquid crystal display device according to claim 9, wherein conditions of said stages of 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 4, wherein

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

24. 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.

31. 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.

5. 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, thus forming a liquid crystal layer, comprising:

deforming said substrates midway through said ultraviolet irradiation.

10. The method for manufacture of a liquid crystal display device according to claim 5, wherein:

said ultraviolet irradiation comprises a first ultraviolet irradiation stage and a second ultraviolet irradiation stage after the first ultraviolet irradiation stage; and

the rate of polymerization in the second ultraviolet irradiation stage is higher than the rate of polymerization in the first ultraviolet irradiation stage.

14. The method for manufacture of a liquid crystal display device according to claim 5, comprising:

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

16. The method for manufacture of a liquid crystal display device according to claim 14, 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.

20. The method for manufacture of a liquid crystal display device according to claim 5, wherein

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

25. The method for manufacture of a liquid crystal display device according to claim 5, 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 5, 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, thus forming a liquid crystal layer;

wherein

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

7. The method for manufacture of a liquid crystal display device according to claim 6, wherein a=0.

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

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

said ultraviolet irradiation comprises a first ultraviolet irradiation stage and a second ultraviolet irradiation stage after the first ultraviolet irradiation stage; and

the rate of polymerization in the second ultraviolet irradiation stage is higher than the rate of polymerization in the first ultraviolet irradiation stage.

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 6, comprising:

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

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):

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.