Vertically aligned liquid crystal display device having an optimized viewing angle

• US 20060164581A1
• Filed: 02/09/2006
• Published: 07/27/2006
• Est. Priority Date: 07/12/2002
• Status: Active Grant

• Current Assignee: TCL China Star Optoelectronics Technology Co. Ltd. (TCL Technology Group Corp.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yang, Young-Chol, Kim, Sang-Il, Kim, Tae-Hwan
• Granted Patent: US 7,760,299 B2
• Time in Patent Office: Days
• US Class Current: 349/119
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 1/133637 characterised by the wavelength dispersion
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2202/40 Materials having a particular birefringence, retardation
• CPC Class Codes: G02F 2413/04 Number of plates greater than or equal to 4

Abstract

A method of improving the viewing angle of a vertically-aligned liquid crystal display device is presented. The method involves designing a uniaxial compensation film to provide a retardation value of 200 nm or less for light having a wavelength of about 550 nm. Using this uniaxial compensation film, a display device can be built by obtaining a liquid crystal panel with liquid crystal molecules contained between glass substrates, coupling the uniaxial compensation film to at least one of the glass substrates, and coupling a polarization film and electrodes to the compensation film. Preferably, the uniaxial compensation film has a thickness less than or equal to 50 microns. Where there are multiple compensation films, the total thickness and the total retardation values should be considered.

Claims

1-23. -23. (canceled)

24. A display device comprising:

a first and second glass substrates facing each other with a gap.

a liquid crystal layer interposed between the first glass substrate and the second glass substrates,

wherein the liquid crystal layer comprises liquid crystal molecules whose long axes are oriented orthogonal to the first and second glass substrates;

a first uniaxial compensation film coupled to the first glass substrates, wherein the first uniaxial compensation film has a retardation value less than or equal to 200 nm for light having a wavelength of about 550 nm;

a polarization film coupled to the first uniaxial compensation film; and

a first electrode and a second electrode formed on at least one of the first and second glass substrates.

25. The display device of claim 24, wherein the display device is a transflective type display device.

26. The display device of claim 24, wherein the first uniaxial compensation film has total thickness equal to or less that 50 um.

27. The display device of claim 24, wherein the display device has a viewing angle larger than 75 degrees from the top and larger than 74 degrees from the sides at a contrast ratio of 2:

1.

28. The display device of claim 24, wherein the first uniaxial compensation film has reflective indexes nx, ny, and nz and the reflective indexes nx, ny, and nz satisfy nx=ny>

nz.

29. The display device of claim 28, wherein the total retardation value of the first uniaxial compensation film is less than or equal to 160 nm.

30. The display device of claim 24, further comprising a reverse dispersion phase difference film located between the first uniaxial compensation film and the polarization film.

31. The display device of claim 24, further comprising an additional compensation film coupled to one of the first and second glass substrates.

32. The display device of claim 31, wherein the display device is a transflective type display device.

33. The display device of claim 24, further comprising a second uniaxial compensation film coupled to the second glass substrate, wherein the second uniaxial compensation film has the retardation value less than or equal to 200 nm for light having a wavelength of about 550 nm.

34. The display device of claim 33, wherein the display device is a transflective type.

35. The display device of claim 33, wherein the first and second uniaxial compensation films have total thickness equal to or less that 50 um.

36. The display device of claim 33, wherein the display device has a viewing angle larger than 75 degrees from the top and larger than 74 degrees from the sides at a contrast ratio of 2:

1.

37. The display device of claim 33, wherein the first and second uniaxial compensation films have reflective indexes nx, ny, and nz and the reflective indexes nx, ny, and nz satisfy nx=ny>

nz.

38. The display device of claim 37, wherein the total retardation value of the first and second uniaxial compensation films is less than or equal to 2000 nm.

39. The display device of claim 33, further comprising a reverse dispersion phase difference film located between the first uniaxial compensation film and the polarization film.

40. The display device of claim 33, further comprising an additional compensation film coupled to one of the first and second glass substrates.

41. The display device of claim 40, wherein the display device is a transflective type display device.