Liquid crystal display device

• US 8,665,403 B2
• Filed: 05/16/2011
• Issued: 03/04/2014
• Est. Priority Date: 05/21/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Hirakata, Yoshiharu
• Primary Examiner(s): Vu, Phu
• Application Number:
  US13/108,229
• Publication Number:
  US 20110285943A1
• Time in Patent Office: 1,023 Days
• Field of Search: 349113-114
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making

Abstract

Reflection efficiency of reflected light is improved and white display is efficiently performed in a liquid crystal display device which performs display by reflecting incident external light. A liquid crystal display device with higher visibility and higher image quality is provided. White display is performed utilizing reflected light which is efficiently scattered with the use of a pixel electrode layer whose surface has depressions and projections, whereby reflection efficiency of the reflected light can be improved and white display can be efficiently performed. Further, a liquid crystal display device with higher visibility and higher image quality can be provided.

Claims

1. A liquid crystal display device comprising:

a liquid crystal layer between a first substrate and a second substrate;

a structural body between the first substrate and the liquid crystal layer;

a reflective electrode layer between the structural body and the liquid crystal layer;

a planarizing film between the reflective electrode layer and the liquid crystal layer;

a pixel electrode between the planarizing film and the liquid crystal layer;

a light-transmitting electrode layer between the second substrate and the liquid crystal layer; and

a polarizing plate on a side of the second substrate opposite to a liquid crystal layer side,

wherein the reflective electrode layer has a surface having a depression and a projection,

wherein a peak wavelength range in which transmittance of the light-transmitting electrode layer is increased is included in a wavelength range in which transmittance in a visible light range of the polarizing plate is decreased, and

wherein the pixel electrode and the light-transmitting electrode layer are formed using similar material with each other.

2. The liquid crystal display device according to claim 1, wherein an average value of an inclination angle of the depression and the projection is greater than or equal to 8°

and less than or equal to 22°

.

3. The liquid crystal display device according to claim 1, wherein an average value of a gap of the depression and the projection is greater than 10 μ

m and less than 30 μ

m.

4. The liquid crystal display device according to claim 1, wherein the depression and the projection are arranged in such a manner that 60% or more of gaps of depressions and projections in one pixel are greater than 10 μ

m and less than 30 μ

m.

5. The liquid crystal display device according to claim 1, wherein an intensity ratio between light emitted through the polarizing plate in part of the wavelength range in which the transmittance in the visible light range of the polarizing plate is decreased and light emitted through the polarizing plate in part of a peak wavelength range in which the transmittance in the visible light range of the polarizing plate is increased is greater than or equal to 0.8 and less than or equal to 1.2.

6. The liquid crystal display device according to claim 1, wherein the reflective electrode layer includes a region in which the depression and the projection are arranged in point symmetry or line symmetry.

25. The liquid crystal display device according to claim 1, wherein the structural body and the planarizing film are formed using similar material with each other.

7. A liquid crystal display device comprising:

a liquid crystal layer between a first substrate and a second substrate;

a structural body between the first substrate and the liquid crystal layer;

a reflective electrode layer between the structural body and the liquid crystal layer;

a planarizing film between the reflective electrode layer and the liquid crystal layer;

a pixel electrode between the planarizing film and the liquid crystal layer;

a light-transmitting electrode layer between the second substrate and the liquid crystal layer; and

a polarizing plate on a side of the second substrate opposite to a liquid crystal layer side,

wherein the reflective electrode layer has a surface having a depression and a projection,

wherein a thickness of the light-transmitting electrode layer is set so that a peak wavelength range in which transmittance of the light-transmitting electrode layer is increased is included in a wavelength range in which transmittance in a visible light range of the polarizing plate is decreased, and

wherein the pixel electrode and the light-transmitting electrode layer are formed using similar material with each other.

8. The liquid crystal display device according to claim 7, wherein an average value of an inclination angle of the depression and the projection is greater than or equal to 8°

and less than or equal to 22°

.

9. The liquid crystal display device according to claim 7, wherein an average value of a gap of the depression and the projection is greater than 10 μ

m and less than 30 μ

m.

10. The liquid crystal display device according to claim 7, wherein the depression and the projection are arranged in such a manner that 60% or more of gaps of depressions and projections in one pixel are greater than 10 μ

m and less than 30 μ

m.

11. The liquid crystal display device according to claim 7, wherein an intensity ratio between light emitted through the polarizing plate in part of the wavelength range in which the transmittance in the visible light range of the polarizing plate is decreased and light emitted through the polarizing plate in part of a peak wavelength range in which the transmittance in the visible light range of the polarizing plate is increased is greater than or equal to 0.8 and less than or equal to 1.2.

12. The liquid crystal display device according to claim 7, wherein the reflective electrode layer includes a region in which the depression and the projection are arranged in point symmetry or line symmetry.

26. The liquid crystal display device according to claim 7, wherein the structural body and the planarizing film are formed using similar material with each other.

13. A liquid crystal display device comprising:

a reflective electrode layer over a structural body;

a planarizing film over the reflective electrode layer;

a pixel electrode over the planarizing film;

a liquid crystal layer over the pixel electrode;

a light-transmitting electrode layer over the liquid crystal layer; and

a polarizing plate over the light-transmitting electrode layer,

wherein the reflective electrode layer has a surface having a depression and a projection,

wherein a peak wavelength range in which transmittance of the light-transmitting electrode layer is increased is included in a wavelength range in which transmittance in a visible light range of the polarizing plate is decreased, and

wherein the pixel electrode and the light-transmitting electrode layer are formed using similar material with each other.

14. The liquid crystal display device according to claim 13, wherein an average value of an inclination angle of the depression and the projection is greater than or equal to 8°

and less than or equal to 22°

.

15. The liquid crystal display device according to claim 13, wherein an average value of a gap of the depression and the projection is greater than 10 μ

m and less than 30 μ

m.

16. The liquid crystal display device according to claim 13, wherein the depression and the projection are arranged in such a manner that 60% or more of gaps of depressions and projections in one pixel are greater than 10 μ

m and less than 30 μ

m.

17. The liquid crystal display device according to claim 13, wherein an intensity ratio between light emitted through the polarizing plate in part of the wavelength range in which the transmittance in the visible light range of the polarizing plate is decreased and light emitted through the polarizing plate in part of a peak wavelength range in which the transmittance in the visible light range of the polarizing plate is increased is greater than or equal to 0.8 and less than or equal to 1.2.

18. The liquid crystal display device according to claim 13, wherein the reflective electrode layer includes a region in which the depression and the projection are arranged in point symmetry or line symmetry.

27. The liquid crystal display device according to claim 13, wherein the structural body and the planarizing film are formed using similar material with each other.

19. A liquid crystal display device comprising:

a reflective electrode layer over a structural body;

a planarizing film over the reflective electrode layer;

a pixel electrode over the planarizing film;

a liquid crystal layer over the pixel electrode;

a light-transmitting electrode layer over the liquid crystal layer; and

a polarizing plate over the light-transmitting electrode layer,

wherein the reflective electrode layer has a surface having a depression and a projection,

wherein a thickness of the light-transmitting electrode layer is set so that a peak wavelength range in which transmittance of the light-transmitting electrode layer is increased is included in a wavelength range in which transmittance in a visible light range of the polarizing plate is decreased, and

wherein the pixel electrode and the light-transmitting electrode layer are formed using similar material with each other.

20. The liquid crystal display device according to claim 19, wherein an average value of an inclination angle of the depression and the projection is greater than or equal to 8°

and less than or equal to 22°

.

21. The liquid crystal display device according to claim 19, wherein an average value of a gap of the depression and the projection is greater than 10 μ

m and less than 30 μ

m.

22. The liquid crystal display device according to claim 19, wherein the depression and the projection are arranged in such a manner that 60% or more of gaps of depressions and projections in one pixel are greater than 10 μ

m and less than 30 μ

m.

23. The liquid crystal display device according to claim 19, wherein an intensity ratio between light emitted through the polarizing plate in part of the wavelength range in which the transmittance in the visible light range of the polarizing plate is decreased and light emitted through the polarizing plate in part of a peak wavelength range in which the transmittance in the visible light range of the polarizing plate is increased is greater than or equal to 0.8 and less than or equal to 1.2.

24. The liquid crystal display device according to claim 19, wherein the reflective electrode layer includes a region in which the depression and the projection are arranged in point symmetry or line symmetry.

28. The liquid crystal display device according to claim 19, wherein the structural body and the planarizing film are formed using similar material with each other.