Display device

• US 7,956,957 B2
• Filed: 02/21/2007
• Issued: 06/07/2011
• Est. Priority Date: 02/24/2006
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Egi, Yuji, Nishi, Takeshi, Ishitani, Tetsuji
• Primary Examiner(s): Le; Uyen-Chau N
• Assistant Examiner(s): Bedtelyon; John M
• Application Number:
  US11/677,300
• Publication Number:
  US 20070200978A1
• Time in Patent Office: 1,567 Days
• Field of Search: 349/103, 349/96
• US Class Current: 349/103
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes
• CPC Class Codes: G02F 2203/64 Normally black display, i.e. the off state being black

Abstract

An object is to provide a display device with high contrast ratio. Another object is to manufacture such a high-performance display device at low cost. In a display device having a display element interposed between a pair of light-transmitting substrates, a stack of polarizer-including layers in a parallel nicol state is provided outside each of the light-transmitting substrates. Here, transmission axes of polarizers that are stacked in the stack on one side of the display element and transmission axes of polarizers that are stacked in the stack on another side of the display element are arranged to be displaced from a cross nicol state. Also, a retardation film may be provided between the polarizers that are stacked and the substrate.

Claims

1. A display device comprising:

a first light-transmitting substrate and a second light-transmitting substrate arranged to face each other;

a display element disposed between the first light-transmitting substrate and the second light-transmitting substrate;

a first layer including first stacked polarizers adjacent to the first light-transmitting substrate; and

a second layer including second stacked polarizers adjacent to the second light-transmitting substrate,

wherein the first light-transmitting substrate and the second light-transmitting substrate are disposed between the first layer and the second layer,

wherein the second stacked polarizers are in direct contact with each other,

wherein the second layer includes a pair of protective layers between which the second stacked polarizers are disposed,

wherein transmission axes of the first stacked polarizers are arranged in a parallel nicol state relative to one another,

wherein transmission axes of the second stacked polarizers are arranged in a parallel nicol state relative to one another, and

wherein the transmission axes of the first stacked polarizers are arranged in a cross nicol state with a deviation relative to the transmission axes of the second stacked polarizers.

2. The display device according to claim 1,

wherein the first layer further comprises at least a pair of protective layers, and

wherein one of the first stacked polarizers is disposed between the pair of protective layers.

3. The display device according to claim 1, further comprising a protective layer,

wherein the first layer comprises at least a first polarizer and a second polarizer, and

wherein the protective layer is disposed between the first polarizer and the second polarizer.

4. The display device according to claim 1,

wherein the first layer comprises a first polarizer and a second polarizer, and

wherein the first polarizer is in direct contact with the second polarizer.

5. The display device according to claim 1, further comprising a light source, wherein the second layer is disposed between the display element and the light source.

6. The display device according to claim 1, wherein the transmission axes of the first stacked polarizers and the transmission axes of the second stacked polarizers are arranged in cross nicol state with the deviation in a range of −

3 degrees to +3 degrees.

7. The display device according to claim 1, wherein the display element is a liquid crystal element.

8. The display device according to claim 1, wherein extinction coefficients of absorption axes of the first stacked polarizers are same.

9. The display device according to claim 1, wherein the display device is a liquid crystal display device of a twisted nematic mode.

10. The display device according to claim 1, wherein the display device is a liquid crystal display device of a vertical alignment mode.

11. A display device comprising:

a first light-transmitting substrate and a second light-transmitting substrate arranged to face each other;

a display element disposed between the first light-transmitting substrate and the second light-transmitting substrate;

a first layer including first stacked polarizers adjacent to the first light-transmitting substrate;

a second layer including second stacked polarizers adjacent to the second light-transmitting substrate;

a first retardation film disposed between the first light-transmitting substrate and the first layer; and

a second retardation film disposed between the second light-transmitting substrate and the second layer,

wherein the first light-transmitting substrate and the second light-transmitting substrate are disposed between the first layer and the second layer,

wherein the second stacked polarizers are in direct contact with each other,

wherein the second layer includes a pair of protective layers between which the second stacked polarizers are disposed,

wherein transmission axes of the first stacked polarizers are arranged in a parallel nicol state relative to one another,

wherein transmission axes of the second stacked polarizers are arranged in a parallel nicol state relative to one another, and

wherein the transmission axes of the first stacked polarizers are arranged in a cross nicol state with a deviation relative to the transmission axes of the second stacked polarizers.

12. The display device according to claim 11,

wherein the first layer further comprises at least a pair of protective layers,

wherein one of the first stacked polarizers is disposed between the pair of protective layers.

13. The display device according to claim 11, further comprising a protective layer,

wherein the first layer comprises at least a first polarizer and a second polarizer, and

wherein the protective layer is disposed between the first polarizer and the second polarizer.

14. The display device according to claim 11, wherein the first layer comprises a first polarizer and a second polarizer, and wherein the first polarizer is in direct contact with the second polarizer.

15. The display device according to claim 11, further comprising a light source, wherein the second layer is disposed between the display element and the light source.

16. The display device according to claim 11, wherein the transmission axes of the first stacked polarizers and the transmission axes of the second stacked polarizers are arranged in cross nicol state with the deviation in a range of −

3 degrees to +3 degrees.

17. The display device according to claim 11, wherein the display element is a liquid crystal element.

18. The display device according to claim 11, wherein extinction coefficients of absorption axes of the first stacked polarizers are same.

19. The display device according to claim 11, wherein the display device is a liquid crystal display device of a twisted nematic mode.

20. The display device according to claim 11, wherein the display device is a liquid crystal display device of a vertical alignment mode.

21. A display device comprising:

a first light-transmitting substrate and a second light-transmitting substrate arranged to face each other;

a display element disposed between the first light-transmitting substrate and the second light-transmitting substrate;

a first layer including first stacked polarizers adjacent to the first light-transmitting substrate; and

a second layer including second stacked polarizers adjacent to the second light-transmitting substrate,

wherein the first light-transmitting substrate and the second light-transmitting substrate are disposed between the first layer and the second layer,

wherein the second layer comprises a first polarizer and a second polarizer which are in direct contact with each other,

wherein the second layer further comprises a pair of protective layers between which the first polarizer and the second polarizer are disposed,

wherein a transmission axis of the first polarizer and a transmission axis of the second polarizer are arranged in a parallel nicol state relative to one another,

wherein transmission axes of the first stacked polarizers are arranged in a parallel nicol state relative to one another, and

wherein the transmission axes of the first stacked polarizers are arranged in a cross nicol state with a deviation relative to the transmission axes of the second stacked polarizers.

22. The display device according to claim 21,

wherein the first layer further comprises at least a pair of protective layers, and

wherein one of the first stacked polarizers is disposed between the pair of protective layers.

23. The display device according to claim 21, further comprising a protective layer, wherein the protective layer is disposed between the first polarizer and the second polarizer.

24. The display device according to claim 21,

wherein the first layer comprises a third polarizer and a fourth polarizer, and

wherein the third polarizer is in direct contact with the fourth polarizer.

25. The display device according to claim 21, further comprising a light source, wherein the second layer is disposed between the display element and the light source.

26. The display device according to claim 21, wherein the transmission axes of the first stacked polarizers and the transmission axes of the second stacked polarizers are arranged in cross nicol state with the deviation in a range of −

3 degrees to +3 degrees.

27. The display device according to claim 21, wherein the display element is a liquid crystal element.

28. The display device according to claim 21, wherein extinction coefficients of absorption axes of the first stacked polarizers are same.

29. The display device according to claim 21, wherein the display device is a liquid crystal display device of a twisted nematic mode.

30. The display device according to claim 21, wherein the display device is a liquid crystal display device of a vertical alignment mode.

31. A display device comprising:

a first light-transmitting substrate and a second light-transmitting substrate arranged to face each other;

a display element disposed between the first light-transmitting substrate and the second light-transmitting substrate;

a first layer including first stacked polarizers adjacent to the first light-transmitting substrate;

a second layer including second stacked polarizers adjacent to the second light-transmitting substrate;

a first retardation film disposed between the first light-transmitting substrate and the first layer; and

a second retardation film disposed between the second light-transmitting substrate and the second layer,

wherein the first light-transmitting substrate and the second light-transmitting substrate are disposed between the first layer and the second layer,

wherein the second layer comprises a first polarizer and a second polarizer which are in direct contact with each other,

wherein the second layer further comprises a pair of protective layers between which the first polarizer and the second polarizer are disposed,

wherein a transmission axis of the first polarizer and a transmission axis of the second polarizer are arranged in a parallel nicol state relative to one another,

wherein transmission axes of the first stacked polarizers are arranged in a parallel nicol state relative to one another, and

wherein the transmission axes of the first stacked polarizers are arranged in a cross nicol state with a deviation relative to the transmission axes of the second stacked polarizers.

32. The display device according to claim 31,

wherein the first layer further comprises at least a pair of protective layers,

wherein the one of the first stacked polarizers is disposed between the pair of protective layers.

33. The display device according to claim 31, further comprising a protective layer, wherein the protective layer is disposed between the first polarizer and the second polarizer.

34. The display device according to claim 31,

wherein the first layer comprises a third polarizer and a fourth polarizer, and

the third polarizer is in direct contact with the fourth polarizer.

35. The display device according to claim 31, further comprising a light source, wherein the second layer is disposed between the display element and the light source.

36. The display device according to claim 31, wherein the transmission axes of the first stacked polarizers and the transmission axes of the second stacked polarizers are arranged in cross nicol state with the deviation in a range of −

3 degrees to +3 degrees.

37. The display device according to claim 31, wherein the display element is a liquid crystal element.

38. The display device according to claim 31, wherein extinction coefficients of absorption axes of the first stacked polarizers are same.

39. The display device according to claim 31, wherein the display device is a liquid crystal display device of a twisted nematic mode.

40. The display device according to claim 31, wherein the display device is a liquid crystal display device of a vertical alignment mode.