Liquid crystal display device and electronic device using same

• US 5,986,731 A
• Filed: 08/07/1998
• Issued: 11/16/1999
• Est. Priority Date: 08/07/1997
• Status: Expired due to Term

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Iijima, Chiyoaki
• Primary Examiner(s): Dang, Hung Xuan
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US09/131,311
• Time in Patent Office: 466 Days
• Field of Search: 349/96, 349/113, 349/117, 349/179, 359/487, 359/488, 359/495, 359/494, 359/500, 359/485
• US Class Current: 349/117
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133533 Colour selective polarisers G02F1/1347 takes precedence
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133637 characterised by the wavelength dispersion
• CPC Class Codes: G02F 1/1397 the twist being substantially higher than 90°, e.g. STN-, SBE-, OMI-LC cells
• CPC Class Codes: G02F 2201/346 distributed (Bragg) reflector
• CPC Class Codes: G02F 2203/05 wavelength dependent
• CPC Class Codes: G02F 2203/09 transflective
• CPC Class Codes: G02F 2413/02 Number of plates being 2

Abstract

The present invention relates to a liquid crystal display device, particularly a liquid crystal display device provided with a retardation film, and an electronic device using the same, and provides a liquid crystal display device which satisfactorily and certainly eliminates coloring in the ON-state as well as in the OFF-state and gives a good contrast, and an electronic device using the same. The invention provides a liquid crystal display device comprising a liquid crystal display panel having a liquid crystal layer and a retardation film for eliminating coloring caused on the liquid crystal display panel; wherein a polarized light separator comprising a first film having birefringence and a second film not having birefringence is arranged at least on one side of the liquid crystal display panel; the ratio B_LC /B_RF of the wavelength dispersion B_LC of refractive index anisotropy in the liquid crystal display panel to the wavelength dispersion of retardation in the retardation film is at least 1.02; and the ratio R₄₅₀ /R₆₅₀ of the reflectivity R₄₅₀ at a wavelength of 450 nm of the polarized light separator to the reflectivity R₆₅₀ at a wavelength of 650 nm is at least 1.

Claims

1. A liquid crystal display device comprising:

a liquid crystal display panel having a liquid crystal layer;

a polarized light separator, arranged at least on one side of said liquid crystal display panel, having a ratio R₄₅₀ /R₆₅₀ of the reflectivity R₄₅₀ at a wavelength of 450 nm to the reflectivity R₆₅₀ at a wavelength of 650 nm of at least 1;

wherein said liquid crystal display device has a retardation film for eliminating coloring occurring in said liquid crystal display panel; and

a ratio of the wavelength dispersion B_LC of refractive anisotropy index in said liquid crystal layer to the wavelength dispersion B_RF of retardation in said retardation film is at least 1.02.

2. A liquid crystal display device according to claim 1, wherein said ratio R₄₅₀ /R₆₅₀ is less than or equal to 3.

3. A liquid crystal display device according to claim 1, wherein said polarized light separator is provided with a first layer having birefringence and a second layer not having birefringence, and the refractive index of said first layer is substantially equal to the refractive index of said second layer.

4. A liquid crystal display device according to claim 1, wherein said liquid crystal layer is a nematic liquid crystal layer having a twisted alignment within a range of from 180 to 360°

.

5. A liquid crystal display device according to claim 1, wherein said retardation film is a polymer film.

6. A liquid crystal display device according to claim 1, wherein a side of said liquid crystal display panel opposite to said polarized light separator is provided with a reflector.

7. An electronic device having a liquid crystal display device as the display section thereof, said liquid crystal display device comprising:

a liquid crystal display panel having a liquid crystal layer;

a polarized light separator, arranged at least on one side of said liquid crystal display panel, having a ratio R₄₅₀ /R₆₅₀ of the reflectivity R₄₅₀ at a wavelength of 450 nm to the reflectivity R₆₅₀ at a wavelength of 650 nm of at least 1;

wherein said liquid crystal display device has a retardation film for eliminating coloring occurring in said liquid crystal display panel; and

a ratio of the wavelength dispersion B_LC of refractive index anisotrophy in said liquid crystal layer to the wavelength dispersion B_RF of retardation in said retardation film is at least 1.02.

8. A liquid cyrstal display device comprising:

a liquid crystal display panel having a liquid crystal layer;

a polarized light separator operatively associated with liquid crystal display panel, said light separator having a reflectivity ratio R₄₅₀ /R₆₅₀ of at least one wherein R₄₅₀ is the reflectivity of said light separator at a wavelength of 450 nm and R₆₅₀ is the reflectivity of said light separator at a wavelength of 650 nm; and

a retardation film operatively associated with said liquid cyrstal display panel for eliminating coloring occurring in said liquid cyrstal display panel, wherein a ratio B_LC /B_RF is at least 1.02 where B_LC is the wavelength dispersion of refractive index anisotrophy in said liquid crystal layer and B_RF is the wavelength dispersion of retardation in said retardation film.

9. The liquid cyrstal display device of claim 8 wherein said reflectivity ratio R₄₅₀ /R₆₅₀ is less than or equal to 3.

10. The liquid cyrstal display device of claim 8 wherein said polarized light separator includes a first birefringence layer and a second non-birefringence layer, said first layer having a refractive index substantially equal to a refractive index of said second layer.

11. The liquid cyrstal display device of claim 8 wherein said liquid crystal layer is a nematic layer with a twist alignment of 180 to 360°

.

12. The liquid cyrstal display device of claim 8 within said retardation film is a polymer film.

13. The liquid cyrstal display device of claim 8 further comprising a reflector disposed on said liquid crystal display panel opposite said polarized light separator.