Liquid crystal display and method of manufacturing the same and method of driving the same

• US 6,504,592 B1
• Filed: 06/13/2000
• Issued: 01/07/2003
• Est. Priority Date: 06/16/1999
• Status: Active Grant

• Current Assignee: Gold Charm Limited (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Suzuki, Seiji, Hirai, Yoshihiko, Sumiyoshi, Ken, Yamamoto, Yuji, Suzuki, Teruaki, Sakamoto, Michiaki, Suzuki, Masayoshi, Kanoh, Hiroshi, Ishii, Toshiya, Okamoto, Mamoru, Matsuyama, Hiroaki, Kawada, Kiyomi, Takatori, Ken-Ichi
• Primary Examiner(s): DUDEK, JAMES A
• Application Number:
  US09/593,119
• Time in Patent Office: 938 Days
• Field of Search: 349/110, 349/111, 349/141, 349/129
• US Class Current: 349/129
• 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 1/13373 Disclination line; Reverse tilt
• CPC Class Codes: G02F 1/13394 spacers regularly patterned on the cell subtrate, e.g. walls, pillars G02F1/133377 takes precedence
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/136218 Shield electrodes
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G02F 2201/122 having a particular pattern

Abstract

A liquid crystal display having a wide viewing angle and easily manufactured. The liquid crystal display comprises an upper substrate and a lower substrate, and a liquid crystal material disposed between the upper substrate and the lower substrate. The liquid crystal display has a conductive protrusion disposed on the surface of the upper substrate opposing to the lower substrate. The conductive protrusion is disposed over a scanning electrode line or a signal electrode line and has the same potential as that of the upper electrode. As another structure, each of pixel electrodes on the lower substrate has a smaller area than that of a common electrode on the upper substrate and is covered by the common electrode, and each of the pixel electrodes comprises an electrode portion having approximately symmetrical shape.

Claims

1. A liquid crystal display comprising:

an upper substrate and a lower substrate, wherein at least one of said upper substrate and said lower substrate is a transparent substrate;

an upper electrode disposed on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, and a lower electrode disposed on the surface of said lower substrate which surface of said lower substrate opposes to said upper substrate, wherein at least one of said upper electrode and lower electrode disposed on said transparent substrate is transparent;

a liquid crystal material disposed between said upper electrode and said lower electrode;

a scanning electrode line and a signal electrode line disposed on the surface of said lower substrate which surface of said lower substrate opposes to said upper substrate;

a switching element for controlling application of a voltages to said lower electrode, wherein said application of a voltage to said lower electrode by said switching element is controlled by application of voltages to said scanning electrode line and said signal electrode line; and

a conductive protrusion disposed on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, wherein said conductive protrusion is disposed over said scanning electrode line or said signal electrode line and has the same potential as that of said upper electrode.

2. A liquid crystal display as set forth in claim 1, wherein said conductive protrusion comprises:

a protruded portion disposed on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, said protruded portion being disposed over said scanning electrode line or said signal electrode line; and

a part of said upper electrode covering said protruded portion.

3. A liquid crystal display as set forth in claim 1, wherein said upper substrate is an upper transparent substrate and said conductive protrusion comprises:

a protruded portion disposed on the surface of said upper transparent substrate which surface of said upper substrate opposes to said lower substrate, said protruded portion being disposed over said scanning electrode line or said signal electrode line; and

a part of said upper transparent electrode covering a side surface of said protruded portion.

4. A liquid crystal display as set forth in claim 2, wherein said protruded portion comprises color filter layers or transparent resin layers which are piled on the surface of said upper transparent substrate opposing to said lower substrate.

5. A liquid crystal display as set forth in claim 1, wherein the width of said conductive protrusion is substantially equal to or larger than the width of said scanning electrode line or said signal electrode line.

6. A liquid crystal display as set forth in claim 1, further comprising a lower insulating film which covers said scanning electrode line and, said signal electrode line and which contacts with said conductive protrusion.

7. A liquid crystal display as set forth in claim 1, wherein at least one of said upper electrode and said lower electrode further comprises a projection which is different from said conductive protrusion and which is used for dividing alignment of said liquid crystal material.

8. A liquid crystal display as set forth in claim 1, wherein at least one of said upper electrode and said lower electrode further comprises a nonconductive opening portion which is used for dividing alignment of said liquid crystal material.

9. A liquid crystal display as set forth in claim 1, wherein said conductive protrusion is electrically coupled with said scanning electrode line or said signal electrode line.

10. A liquid crystal display as set forth in claim 9, further comprising a conductive contact portion disposed on said scanning electrode line or said signal electrode line, wherein said conductive protrusion and said conductive contact portion contact with each other.

11. A liquid crystal display as set forth in claim 1, further comprising spacers dispersed in a space between said upper substrate and said lower substrate.

12. A liquid crystal display as set forth in claim 1, wherein:

said liquid crystal display has a plurality of pixel areas surrounded by said scanning electrode lines and signal electrode lines;

said lower electrode comprises a plurality of pixel electrodes each corresponding to said pixel area;

each of said pixel area has a predetermined symmetry center point; and

said conductive protrusions are disposed centrosymmetrically with respect to said symmetry center point.

13. A liquid crystal display as set forth in claim 12, wherein said symmetry center point is substantially in the center of a corresponding pixel area.

14. A liquid crystal display as set forth in claim 12, wherein, in each of said pixel area, at least one of said upper electrode and said pixel electrode further comprises a projection which is different from said conductive protrusion and which is used for dividing alignment of said liquid crystal material, and wherein said projection is disposed on a predetermined line which substantially passes said symmetry center point.

15. A liquid crystal display as set forth in claim 12, wherein at least one of said upper electrode and said lower electrode further comprises a nonconductive opening portion which is used for dividing alignment of said liquid crystal material, and wherein said nonconductive opening portion is disposed on a predetermined line which substantially passes said symmetry center point.

16. A liquid crystal display as set forth in claim 1, wherein:

said liquid crystal display has a plurality of pixel areas surrounded by said scanning electrode lines and signal electrode lines;

said lower electrode comprises a plurality of pixel electrodes each corresponding to said pixel area;

each of said pixel area has a predetermined symmetry center line; and

said conductive protrusions are disposed symmetrically with respect to said symmetry center line.

17. A liquid crystal display as set forth in claim 16, wherein said symmetry center line is substantially passes the center of a corresponding pixel area.

18. A liquid crystal display as set forth in claim 16, wherein, in each of said pixel area, at least one of said upper electrode and said pixel electrode further comprises a projection which is different from said conductive protrusion and which is used for dividing alignment of said liquid crystal material, and wherein said projection is disposed substantially on said symmetry center line.

19. A liquid crystal display as set forth in claim 16, wherein at least one of said upper electrode and said lower electrode further comprises a nonconductive opening portion which is used for dividing alignment of said liquid crystal material, and wherein said nonconcductive opening portion is disposed substantially on said symmetry center line.

20. A liquid crystal display as set forth in claim 1, wherein said liquid crystal material is a nematic liquid crystal material, a cholesteric liquid crystal material, or a discotic liquid crystal material.

21. A liquid crystal display as set forth m claim 20, wherein an operation mode of said liquid crystal material is twisted nematic, STN super twisted nematic, homogeneous, homeotropic, in-plain switching, π

-cell, cholesteric phase transition, polymer dispersion, or polymer network.

22. A method of manufacturing a liquid crystal display comprising:

(a) forming a wiring electrode line on the surface of a lower substrate which surface of said lower substrate opposes to an upper substrate, forming an insulating film covering said wiring electrode line, forming a lower electrode on said insulating film, and forming a switching element for applying a voltage to said lower electrode;

(b) forming a protruded portion on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, wherein said protruded portion is located substantially just above said wiring electrode line when said lower substrate and said upper substrate are opposed to each other;

(c) forming an upper electrode covering whole portion of said protruded portion and the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, wherein at least one of said upper substrate and said lower substrate is a transparent substrate, and at least one of said upper electrode and lower electrode disposed on said transparent substrate is transparent;

(d) opposing said lower substrate and said upper substrate such that said protruded portion is located substantially just above said wiring electrode line; and

(e) injecting a liquid crystal material between said lower substrate and upper substrate.

23. A method of manufacturing a liquid crystal display as set forth in claim 22, wherein said step (b) comprises forming said protruded portion by piling a plurality of color filters on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate.

24. A method of manufacturing a liquid crystal display as set forth in claim 22, wherein said step (b) comprises piling a plurality of transparent resin layers on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate and removing piled transparent resin layers except portions corresponding to said protruded portions.

25. A method of manufacturing a liquid crystal display as set forth in claim 22, wherein the width of said protruded portion is substantially equal to or larger than the width of said wiring electrode line.

26. A method of manufacturing a liquid crystal display as set forth in claim 22, further comprising:

(f) forming a projection which is different from said protruded portion on at least one of said upper electrode and said lower electrode.

27. A method of manufacturing a liquid crystal display as set forth in claim 22, Other comprising:

(g) removing a portion of at least one of said upper electrode and said lower electrode.

28. A method of manufacturing a liquid crystal display as set forth in claim 22, further comprising:

(h) forming a conductive contact portion on said wiring electrode line, said conductive contact portion being electrically coupled with said wiring electrode line;

wherein said step (d) further comprises disposing said conductive contact portion and said upper electrode covering said protruded portion such that said conductive contact portion and said upper electrode covering said protruded portion contact with each other.

45. A method of manufacturing a liquid crystal display as set forth in claim 22, further comprising forming spacers dispersed in a space between said upper substrate and said lower substrate.

46. A method of manufacturing a liquid crystal display as set forth in claim 22, wherein said liquid crystal material is a nematic liquid crystal material, a cholesteric liquid crystal material, or a discotic liquid crystal material.

47. A method of manufacturing a liquid crystal display as set forth in claim 22, wherein an operation mode of said liquid crystal material is twisted nematic, STN super twisted nematic, homogeneous, homeotropic, in-plain switching, π

-cell, cholesteric phase transition, polymer dispersion, or polymer network.

29. A method of manufacturing a liquid crystal display having a plurality of pixel areas, said method comprising:

(a) forming wiring electrode lines on the surface of a lower substrate which surface of said lower substrate opposes to an upper substrate such that said wiring electrode lines surround respective pixel areas, forming an insulating film covering said wiring electrode lines, forming, for each pixel area, a pixel electrode which does not coupled with said wiring electrode line, and forming a switching element for controlling an application of a voltage to said pixel electrode;

(b) forming protruded portions on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, wherein said protruded portions are located at portions centrosymmetrical with respect to a predetermined symmetry center point in each pixel area, and are located substantially just above said wiring electrode lines when said lower substrate and said upper substrate are opposed to each other;

(c) forming an upper electrode covering whole portion of said protruded portions and the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate;

(d) opposing said lower substrate and said upper substrate such that said protruded portions are located substantially just above said wiring electrode lines and such that each of said pixel areas is formed; and

(e) injecting a liquid crystal material between said lower substrate and upper substrate.

30. A method of manufacturing a liquid crystal display as set forth in claim 29, wherein said symmetry center point is substantially in the center of a corresponding pixel area.

31. A method of manufacturing a liquid crystal display as set forth in claim 29, further comprising:

(f) forming a projection which is different from said protruded portion on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate;

wherein said step (c) comprises forming an upper transparent electrode covering said surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, said protruded portion and said projection.

32. A method of manufacturing a liquid crystal display as set forth in claim 31, wherein said step (f) comprises forming a projection which is different from said protruded portion on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate such that said projection is located on a predetermined line substantially passing through said symmetry center point.

33. A method of manufacturing a liquid crystal display as set forth in claim 29, further comprising:

(g) removing a portion of said upper electrode except said protruded portion.

34. A method of manufacturing a liquid crystal display as set forth in claim 33, wherein said step (g) comprises removing said upper electrode existing on a predetermined line substantially passing through said symmetry center point.

35. A method of manufacturing a liquid crystal display as set forth in claim 29, further comprising:

(h) removing a portion of said lower electrode.

36. A method of manufacturing a liquid crystal display as set forth in claim 35, wherein said step (h) comprises removing said lower electrode existing on a predetermined line substantially passing through said symmetry center point.

37. A method of manufacturing a liquid crystal display having a plurality of pixel areas, said method comprising:

(a) forming wiring electrode lines on the surface of a lower substrate which surface of said lower substrate opposes to an upper substrate such that said wiring electrode lines surround respective pixel areas, forming an insulating film covering said wiring electrode lines, forming, for each pixel area, a pixel electrode which does not coupled with said wiring electrode line, and forming a switching element for controlling an application of a voltage to said pixel electrode;

(b) forming protruded portions on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, wherein said protruded portions are located at portions symmetrical with respect to a predetermined symmetry center line in each pixel area, and are located substantially just above said wiring electrode lines when said lower substrate and said upper substrate are opposed to each other;

(c) forming an upper electrode covering whole portion of said protruded portions and the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate;

(d) opposing said lower substrate and said upper substrate such that said protruded portions are located substantially just above said wiring electrode lines and such that each of said pixel areas is formed; and

(e) injecting a liquid crystal material between said lower substrate and upper substrate.

38. A method of manufacturing a liquid crystal display as set forth in claim 37, wherein said symmetry center line is substantially in the center of a corresponding pixel area.

39. A method of manufacturing a liquid crystal display as set forth in claim 37, further comprising:

(f) forming a projection which is different from said protruded portion on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate;

wherein said step (c) comprises forming an upper transparent electrode covering said surface of said upper substrate which surface of said upper substrate opposes to said lower substrate, said protruded portion and said projection.

40. A method of manufacturing a liquid crystal display as set forth in claim 39, wherein said step (f) comprises forming a projection which is different from said protruded portion on the surface of said upper substrate which surface of said upper substrate opposes to said lower substrate such that said projection is substantially located on said symmetry center line.

41. A method of manufacturing a liquid crystal display as set forth in claim 37, further comprising:

(g) removing a portion of said upper electrode except said protruded portion.

42. A method of manufacturing a liquid crystal display as set forth in claim 41, wherein said step (g) comprises removing said upper electrode substantially existing on said symmetry center line.

43. A method of manufacturing a liquid crystal display as set forth in claim 37, further comprising:

(h) removing a portion of said lower electrode.

44. A method of manufacturing a liquid crystal display as set forth in claim 43, wherein said step (h) comprises removing said lower electrode substantially existing on said symmetry center line.