Liquid Crystal Display Device, Optical Compensatory Sheet, and Polarizer and Liquid Crystal Display Device Employing the Same

• US 20090122243A1
• Filed: 12/28/2005
• Published: 05/14/2009
• Est. Priority Date: 12/28/2004
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Sugiyama, Susumu, Saitoh, Yukito, Nakayama, Hajime, Aminaka, Eiichiro
• Granted Patent: US 8,049,850 B2
• Time in Patent Office: Days
• US Class Current: 349/118
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• 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 1/133528 Polarisers
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• 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 2201/50 Protective arrangements
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: G02F 2203/05 wavelength dependent
• CPC Class Codes: G02F 2413/02 Number of plates being 2

Abstract

A liquid crystal display device comprising a liquid crystal panel in which liquid crystals having negative dielectric anisotropy are interposed between upper substrate and lower substrate that have been vertically oriented on the surface, the orientation of the liquid crystals being almost vertical with no applied voltage, almost horizontal when a predetermined voltage is applied, and tilted when a smaller voltage than the predetermined voltage is applied; a first polarizer and a second polarizer disposed on both sides of the liquid crystal panel such that the absorption axes of the polarizers are perpendicular to each other; a first retardation film disposed between the liquid crystal panel and the first polarizer; and a second retardation film disposed between the liquid crystal panel and the second polarizer, wherein the polarizer comprises a polarizing film and a pair of protective films having the polarizing film in between, and wherein at least one of the protective films is a cellulose acylate film satisfying:

0≦Re₍₆₃₀₎≦10 and |Rth₍₆₃₀₎|≦25

Claims

1. A liquid crystal display device comprising a liquid crystal panel in which liquid crystals having negative dielectric anisotropy are interposed between upper substrate and lower substrate that have been vertically oriented on the surface, the orientation of the liquid crystals being almost vertical with no applied voltage, almost horizontal when a predetermined voltage is applied, and tilted when a smaller voltage than the predetermined voltage is applied;

a first polarizer and a second polarizer disposed on both sides of the liquid crystal panel such that the absorption axes of the polarizers are perpendicular to each other;

a first retardation film disposed between the liquid crystal panel and the first polarizer; and

a second retardation film disposed between the liquid crystal panel and the second polarizer, wherein the polarizer comprises a polarizing film and a pair of protective films having the polarizing film in between, and wherein at least one of the protective films is a cellulose acylate film satisfying;

0≦

Re₍₆₃₀₎≦

10 and |Rth₍₆₃₀₎|≦

25.

2. The liquid crystal display device according to claim 1, wherein the first retardation film satisfies:

50≦

Re₍₅₈₉₎≦

100 and 30≦

Rth₍₅₈₉₎≦

80, and

the second retardation film satisfies;

Re₍₅₈₉₎≦

20 and 100≦

Rth₍₅₈₉₎|≦

300.

3. The liquid crystal display device according to claim 1, wherein the cellulose acylate film satisfies:

0≦

Re₍₆₃₀₎≦

5 and |Rth₍₆₃₀₎|≦

10.

4. The liquid crystal display device according to claim 1, wherein the cellulose acylate film satisfies:

0≦

Re₍₆₃₀₎≦

3 and |Rth₍₆₃₀₎|≦

5.

5. The liquid crystal display device according to claim 1, wherein the cellulose acylate film contains at least one compound reducing the retardation in the direction of film thickness, Rth, in an amount satisfying the following formulas (I) and (II):

(Rth(A)−

Rth(0))/A≦

−

1.0, 

 

(I)

0.01≦

A≦

30 

 

(II)

wherein Rth(A) is the Rth (nm) of the film containing A % of the compound reducing Rth, Rth(0) is the Rth (nm) of the film not containing the compound reducing Rth, and A is the weight (%) of the compound based on 100% of the weight of the raw material polymer of the film.

6. The liquid crystal display device according to claim 1, wherein the cellulose acylate film is made of cellulose acylate with a degree of acyl substitution of 2.85 to 3.00 containing at least one compound reducing Re_(λ

) and Rth<sub>(λ

)</sub>, in an amount of 0.01 to 30% by weight relative to the cellulose acylate solids content.

7. The liquid crystal display device according to claim 1, wherein the cellulose acylate film contains at least one compound reducing |Re₍₄₀₀₎−

Re₍₇₀₀₎| and |Rth₍₄₀₀₎−

Rth₍₇₀₀₎| of the film, in an amount of 0.01 to 30% by weight relative to the cellulose acylate solids content.

8. The liquid crystal display device according to claim 1, wherein the cellulose acylate film has a thickness of 10 to 120 μ

m.

9. A liquid crystal display device comprising a pair of substrates disposed to face each other, at least one of them having an electrode, and a nematic liquid crystal material interposed between the pair of substrates;

and having a liquid crystal cell having a liquid crystal layer in which the liquid crystal molecules of the nematic liquid crystal material align approximately vertically to the surfaces of the pair of substrates during dark state, a first polarizing film and a second polarizing film disposed such that the liquid crystal cell is interposed between the films, and optical compensatory films respectively disposed between the liquid crystal layer and the first polarizing film, and between the liquid crystal layer and the second polarizing film,

wherein a cellulose acylate film is disposed between the optical compensatory film and at least one of the polarizing film and the liquid crystal layer,

wherein when the thickness of the liquid crystal layer is d (unit;

nm), the refractive index anisotropy at a wavelength λ

(unit;

nm) is Δ

n<sub>(λ

)</sub>, the sum of the in-plane retardations of the optical compensatory film and the cellulose acylate film at the wavelength λ

is Re<sub>sum(λ

)</sub>, and the sum of the retardations of the optical compensatory film and the cellulose acylate film in the thickness direction at the wavelength λ

is Rth<sub>sum(λ

)</sub>, with respect to at least two different wavelengths in the wavelength range of 380 nm to 780 nm, the following formulas (I) to (IV) are satisfied;

200≦

Δ

n<sub>(λ

)</sub>×

d≦

1000, 

 

(I)

Rth_sum(λ

)/λ

=A×

Δ

n<sub>(λ

)</sub>×

d/λ

+B, 

 

(II)

Re_sum(λ

)/λ

=C×

λ

/{Δ

n<sub>(λ

)</sub>×

d}+D, and 

 

(III)

0.488≦

A≦

0.56,

B=−

0.0567,

−

0.041≦

C≦

0.016, and

D=0.0939; and

 

 

(IV)

wherein when the in-plane retardation of the cellulose acylate film at the wavelength λ

(unit;

nm) is Re<sub>2(λ

)</sub>, and the retardation in the thickness direction of the cellulose acylate film at the wavelength λ

(unit;

nm) is Rth<sub>2(λ

)</sub>, the following formulas (IX) and (X) are satisfied;

0≦

Re₂₍₆₃₀₎≦

10 and |Rth₂₍₆₃₀₎≦

25, and 

 

(IX)

|Re₂₍₄₀₀₎−

Re₂₍₇₀₀₎|≦

10 and

|Rth₂₍₄₀₀₎−

Rth₂₍₇₀₀₎|≦

35. 

 

(X)

10. The liquid crystal display device according to claim 9, wherein the in-plane slow axis of the optical compensatory film, and the transmission axis of the polarizing film among the first and the second polarizing films, which is disposed closer to the optical compensatory film, are substantially parallel.

11. The liquid crystal display device according to claim 9, wherein with respect to at least two wavelengths differing by 50 nm or greater, the above formulas (I) to (IV) are satisfied.

12. The liquid crystal display device according to claim 9, wherein with respect to all wavelengths of 450 nm, 550 nm and 650 nm, the above formulas (I) to (IV) are satisfied.

13. A liquid crystal display device comprising a pair of substrates disposed to face each other, at least one of them having an electrode, and a nematic liquid crystal material interposed between the pair of substrates;

and having a liquid crystal cell having a liquid crystal layer in which the liquid crystal molecules of the nematic liquid crystal material align approximately vertically to the surfaces of the pair of substrates during dark state, a first polarizing film and a second polarizing film disposed such that the liquid crystal cell is interposed between the films, an optical compensatory film disposed between the liquid crystal layer and one of the first and second polarizing films, and a cellulose acylate film disposed between the liquid crystal layer and at least one of the first and second polarizing films,

wherein when the thickness of the liquid crystal layer is d (unit;

nm), the refractive index anisotropy at a wavelength λ

(unit;

nm) is Δ

n<sub>(λ

)</sub>, the sum of the in-plane retardations of the optical compensatory film and the cellulose acylate film at the wavelength λ

is Re<sub>sum(λ

)</sub>, and the sum of the retardations of the optical compensatory film and the cellulose acylate film in the thickness direction at the wavelength λ

is Rth<sub>sum(λ

)</sub>, with respect to at least two different wavelengths in the wavelength range of 380 nm to 780 nm, the following formulas (V) to (VIII) are satisfied;

200≦

Δ

n<sub>(λ

)</sub>×

d≦

1000, 

 

(V)

Rth_sum(λ

)/λ

=E×

Δ

n<sub>(λ

)</sub>×

d/λ

, 

 

(VI)

Re_sum(λ

)/λ

=F×

λ

/{Δ

n<sub>(λ

)</sub>×

d}+G, and 

 

(VII)

0.726≦

E≦

0.958,

0.0207≦

F≦

0.0716, and

G=0.032; and

 

 

(VIII)

wherein when the in-plane retardation of the cellulose acylate film at the wavelength λ

(unit;

nm) is Re<sub>2(λ

)</sub>, and the retardation in the thickness direction of the cellulose acylate film at the wavelength λ

(unit;

nm) is Rth<sub>2(λ

)</sub>, the following formulas (IX) and (X) are satisfied;

0≦

Re₂₍₆₃₀₎≦

10 and |Rth₂₍₆₃₀₎|≦

25, and 

 

(IX)

|Re₂₍₄₀₀₎−

Re₂₍₇₀₀₎|≦

10 and

|Rth₂₍₄₀₀₎−

Rth₂₍₇₀₀₎|≦

35. 

 

(X)

14. The liquid crystal display device according to claim 13, wherein the in-plane slow axis of the optical compensatory film, and the transmission axis of the polarizing film among the first and the second polarizing films, which is disposed closer to the optical compensatory film, are substantially parallel.

15. The liquid crystal display device according to claim 13, wherein the angle between the in-plane slow axis of the cellulose acylate film and the transmission axis of the polarizing film among the first and second polarizing films, which is disposed closer to the cellulose acylate film, is between −

10° and

10°

, or between 80° and

110°

.

16. The liquid crystal display device according to claim 13, wherein with respect to at least two wavelengths differing by 50 nm or greater, the above formulas (V) to (VIII) are satisfied.

17. The liquid crystal display device according to claim 13, wherein with respect to all wavelengths of 450 nm, 550 nm and 650 nm, the above formulas (V) to (VIII) are satisfied.

18. An optical compensatory sheet having in order of a transparent support satisfying the following formulas (1) and (2), an optically anisotropic layer A satisfying the following formula (3) disposed thereon, and an optically anisotropic layer C satisfying the following formula (4) disposed thereon:

0≦

Re₍₅₉₀₎≦

10 and |Rth₅₉₀|≦

25, 

 

(1)

|Re₍₄₅₀₎−

Re₍₆₅₀₎|≦

10 and |Rth₍₄₅₀₎−

Rth₍₆₅₀₎|≦

35 

 

(2)

10≦

Re₍₅₉₀₎≦

150 and 0≦

Rth₍₅₉₀₎≦

200 

 

(3)

0≦

Re₍₅₉₀₎≦

10 and 40≦

Rth₍₅₉₀₎≦

400 

 

(4)

wherein Re<sub>(λ

)</sub> is the front retardation value (unit;

nm) at a wavelength of λ

nm, and Rth<sub>(λ

)</sub> is the retardation value (unit;

nm) in the thickness direction at a wavelength of λ

nm.

20. The optical compensatory sheet according to claim 18, wherein the transparent support contains at least one compound reducing Rth_(λ

), in an amount satisfying the following formulas (5) and (6);

(Rth<sub>(λ

)</sub>(A)−

Rth<sub>(λ

)</sub>(0)/A≦

−

1.0, and 

 

(5)

0.01≦

A≦

30 

 

(6)

wherein Rth<sub>(λ

)</sub>(A) is Rth<sub>(λ

)</sub>(nm) of the transparent support containing A % of the compound reducing Rth<sub>(λ

)</sub>;

Rth<sub>(λ

)</sub>(0) is Rth_λ

(nm) of the transparent support not containing the compound reducing Rth<sub>(λ

)</sub>; and

A is the weight (%) of the compound based on 100% by weight of the raw material polymer for the transparent support.

21. The optical compensatory sheet according to claim 18, wherein the transparent support contains at least one compound reducing |Re₍₄₀₀₎−

Re₍₇₀₀₎| and |Rth₍₄₀₀₎−

Rth₍₇₀₀₎|, in an amount of 0.01 to 30% by weight relative to the solids content of the raw material polymer for the support.

22. The optical compensatory sheet according to claim 18, wherein the transparent support is formed from a cellulose acylate film.

23. The optical compensatory sheet according to claim 22, wherein the cellulose acylate film is made of cellulose acylate with a degree of acyl substitution of 2.85 to 3.00 containing at least one compound reducing Re_(λ

) and Rth<sub>(λ

)</sub>, in an amount of 0.01 to 30% by weight relative to the cellulose acylate solids content.

24. The optical compensatory sheet according to claim 18, wherein the film thickness of the transparent support is 10 to 120 μ

m.

25. The optical compensatory sheet according to claim 18, wherein the optically anisotropic layer A is made of a stretched polymer film.

26. The optical compensatory sheet according to claim 18, wherein the optically anisotropic layer A is formed from a liquid crystalline compound.

27. The optical compensatory sheet according to claim 18, wherein the optically anisotropic layer C is made of a stretched polymer film.

28. The optical compensatory sheet according to claim 18, wherein the optically anisotropic layer C is formed from a liquid crystalline compound.

29. The optical compensatory sheet according to claim 18, wherein the optically anisotropic layer C is formed from a non-liquid crystalline compound.

30. The optical compensatory sheet according to claim 18, wherein the wavelength dependence of Re_(λ

) of the optical anisotropic layer A satisfies the following formulas (7) and (8);

Re₍₄₅₀₎/Re₍₅₅₀₎=0.60 to 0.98, and 

 

(7)

Re₍₆₅₀₎/Re₍₅₅₀₎=1.00 to 1.60. 

 

(8)

31. The optical compensatory sheet according to claim 18, wherein the wavelength dependence of Rth_(λ

) of the optical anisotropic layer C satisfies the following formulas (9) and (10);

Rth₍₄₅₀₎/Rth₍₅₅₀₎=1.02 to 1.60, and 

 

(9)

Rth₍₆₅₀₎/Rth₍₅₅₀₎=0.60 to 1.00. 

 

(10)

32. The optical compensatory sheet according to claim 18, wherein the wavelength dependence of Re_(λ

) of the optical anisotropic layer A satisfies the following formulas (7) and (8), while the wavelength dependence of Rth<sub>(λ

)</sub> of the optical anisotropic layer C satisfies the following formulas (9) and (10);

Re₍₄₅₀₎/Re₍₅₅₀₎=0.60 to 0.98, 

 

(7)

Re₍₆₅₀₎/Re₍₅₅₀₎=1.00 to 1.60, 

 

(8)

Rth₍₄₅₀₎/Rth₍₅₅₀₎=1.02 to 1.60, and 

 

(9)

Rth₍₆₅₀₎/Rth₍₅₅₀₎=0.60 to 1.00. 

 

(10)

33. A polarizer having protective films on both sides of a polarizer, wherein at least one of the protective films is the optical compensatory sheet according to claim 18, and the side facing the transparent support is bonded to the polarizer.

34. The polarizer according to claim 33, wherein the protective film contains at least one selected from the group consisting of plasticizer, ultraviolet absorbent, release promoting agent, dye, matting agent and conductive microparticles.

35. The polarizer according to claim 33, wherein at least one layer selected from the group consisting of a hardcoat layer, an anti-glare layer, an anti-reflection layer, an antifouling layer and an antistatic layer is provided on the surface of at least one protective film.

36. A liquid crystal display device having a liquid crystal cell and a pair of polarizers disposed on both sides of the liquid crystal cell, wherein at least one of the polarizers is the polarizer according to claim 33.

37. A liquid crystal display device having a liquid crystal cell and a pair of polarizers disposed on both sides of the liquid crystal cell, wherein the polarizer comprises a polarizer and a pair of protective films having the polarizer interposed in between, and at least one of the protective films is the optical compensatory sheet according to claim 18.

39. The liquid crystal display device according to claim 36, wherein the liquid crystal cell is a VA mode cell.

19. An optical compensatory sheet having in order of a transparent support satisfying the following formulas (1) and (2), an optically anisotropic layer C satisfying the following formula (4) disposed thereon, and an optically anisotropic layer A satisfying the following formula (3) disposed thereon:

0≦

Re₍₅₉₀₎≦

10 and |Rth₍₅₉₀₎≦

25, 

 

(1)

|Re₍₄₅₀₎−

Re₍₇₀₀₎|≦

10 and |Rth₍₄₅₀₎−

Rth₍₆₅₀₎|≦

35 

 

(2)

10≦

Re₍₅₉₀₎≦

150 and 0≦

Rth₍₅₉₀₎≦

200 

 

(3)

0≦

Re₍₅₉₀₎≦

10 and 40≦

Rth₍₅₉₀₎≦

400 

 

(4)

wherein Re<sub>(λ

)</sub> is the front retardation value (unit;

nm) at a wavelength of λ

nm, and Rth<sub>(λ

)</sub> is the retardation value (unit;

nm) in the thickness direction at a wavelength of λ

nm.

38. A liquid crystal display device having a liquid crystal cell and a pair of polarizers disposed on both sides of the liquid crystal cell, wherein the polarizer comprises a polarizer and a pair of protective films having the polarizer interposed in between, and at least one of the protective films is the optical compensatory sheet according to claim 19.