Optical film, its manufacturing method, anti-glare polarizer using the same, and display apparatus

1. An optical film comprising:

a layer including micro concave/convex portions formed on a surface of the layer,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

wherein when light incident on the layer is reflected in a direction of specular reflection there is a deviation angle α from the direction of specular reflection at which a differentiation with respect to d{Log(I(α))}/dα is at a maximum absolute value, where Log(I(α)) represents a logarithm of an intensity of light reflected at the deviation angle α.

2. The optical film according to claim 1 , wherein when an angle showing the maximum absolute value of the differentiation with respect to angle d{Log(I(α))}/dα of the logarithm intensity of reflection Log(I(α)) in the direction of said deviation angle α is assumed to be α 1 and an angle showing a maximum reflection intensity of said logarithm intensity of reflection Log(I(α)) is assumed to be α 0 , a relation of the following equation (1) is satisfied:

Log( I (α0))−Log( I (α1))= kI α{(α1 −α0)−0.5}( k : 0 <kI α1)  (Equation 1).

3. The optical film according to claim 1 , wherein an angle α 1 showing the maximum absolute value of the differentiation with respect to angle d{Log(I(α))}/dα of the logarithm intensity of reflection Log(I(α)) in the direction of said deviation angle α is equal to 6° or less.

4. The optical film according to claim 1 , wherein an angle α 0 showing a maximum value of the logarithm intensity of reflection Log(I(α)) in the direction of said deviation angle α is equal to 0°.

5. The optical film according to claim 1 , wherein said optical film further comprising

a substrate, and

the layer is an anti-glare layer and is provided on said substrate, and

said anti-glare layer contains fine particles and said micro concave/convex portions are formed on the surface by said fine particles.

6. The optical film according to claim 1 , wherein said micro concave/convex portions are obtained by coating said substrate with a coating material containing fine particles and a resin, aggregating said fine particles by a convection of said coating material, and hardening said coating material.

7. The optical film according to claim 1 , wherein an average particle size of said fine particles lies within a range from 1.5 μm or more to 7.5 μm or less, and

an average film thickness of the layer lies within a range from 4 μm or more to 15 μm or less.

8. An optical film comprising:

a layer including micro concave/convex portions formed on a surface of the layer,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

a differentiation d{P(β)}/dβ of a histogram P(β) to an inclination angle β of said micro concave/convex portions has a maximum absolute value.

9. The optical film according to claim 8 , wherein when an angle showing the maximum absolute value of a differentiation with respect to angle d{Log(P(β))}/dβ of a logarithm histogram Log(P((β)) to said inclination angle β is assumed to be β 1 and an angle showing a maximum frequency of said logarithm histogram Log(P(β))is assumed to be β 0 , a relation of the following equation (2) is satisfied:

Log( P (β0))−Log( P (β1))= kP β{(β1−β0)−0.5}( k :0 <kP β≦1)  (Equation 2).

10. The optical film according to claim 5 , wherein an angle β 1 showing the maximum absolute value of a differentiation d{P(β)}/dβ of a histogram P(β) to said inclination angle β is equal to 3° or less.

11. The optical film according to claim 8 , wherein an angle β 0 at which a histogram P(β) to said inclination angle β shows a maximum frequency is equal to 0°.

12. The optical film according to claim 8 , wherein

a value C(2.0) of transmitted image clarity measured by using an optical comb having a comb width of 2 mm in accordance with JIS-K7105 is equal to 30% or more, and

a ratio C(0.125)/C(2.0) of the value C(2.0) measured by using said optical comb having the comb width of 2 mm and a value C(0.125) measured by using an optical comb having a comb width of 0.125 mm is equal to 0.1 or more.

13. An optical film comprising:

a layer including micro concave/convex portions formed on a surface of the layer,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm,

a value C(2.0) of transmitted image clarity measured by using an optical comb having a comb width of 2 mm in accordance with JIS-K7105 is equal to 30% or more, and

a ratio C(0.125)/C(2.0) of the value C(2.0) measured by using said optical comb having the comb width of 2 mm and a value C(0.125) measured by using an optical comb having a comb width of 0.125 mm is equal to 0.1 or more.

14. A method of manufacturing an optical film, the method comprising:

forming a layer including micro concave/convex portions on a surface of the layer, and forming said micro concave/convex portions by a shape transfer method, a sand blasting method, or a method of coating with a coating material containing a resin and fine particles,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

wherein when light incident on the layer is reflected in a direction of specular reflection there is a deviation angle α from the direction of specular reflection at which a differentiation with respect to d{Log(I(α))}/dα is at a maximum absolute value, where Log(I(α)) represents a logarithm of an intensity of light reflected at the deviation angle α.

15. The method of manufacturing the optical film according to claim 14 , wherein the forming step of said micro concave and convex portions includes:

supplying a resin containing an ionizing radiation-curable resin or a thermosetting resin into a die; and

hardening and exfoliating the resin supplied to said die.

16. The method of manufacturing the optical film according to claim 14 , wherein said forming step of said micro concave and convex portions includes:

coating a substrate with the coating material containing an ionizing radiation-curable resin or a thermosetting resin as a resin and the fine particles; and

drying and hardening said coating material coated onto said substrate, and

in the step of hardening said coating material, a temperature of said substrate coated with said coating material is adjusted.

17. The method of manufacturing the optical film according to claim 14 , wherein said forming step of said micro concave and convex portions includes:

coating a substrate with the coating material containing an ionizing radiation-curable resin or a thermosetting resin as a resin and the fine particles; and

drying and hardening said coating material coated onto said substrate, and

a specific gravity difference between said fine particles and liquid components contained in said coating material is adjusted, a proper sedimentation and/or aggregation of said fine particles is caused, and thereafter, said substrate is coated with said coating material.

18. The manufacturing method of the optical film according to claim 14 , wherein said forming step of said micro concave and convex portions includes:

coating a substrate with the coating material containing an ionizing radiation-curable resin or a thermosetting resin as a resin and the fine particles; and

drying and hardening said coating material coated onto said substrate, and

a surface tension difference between said fine particles and said resin in said coating material is adjusted.

19. A method of manufacturing an optical film, the method comprising:

forming a layer including micro concave/convex portions on a surface of the layer, and forming said micro concave/convex portions by a shape transfer method, a sand blasting method, or a method of coating the surface with a resin containing fine particles,

wherein an average horizontal interval between minimum depths of the micro concave portion and maximum heights of the convex portions is equal ranges from 5 to 300 μm, and

a differentiation d{P(β)}/dβ of a histogram P(β) to an inclination angle β of said micro concave/convex portions has a maximum absolute value.

20. A method of manufacturing an optical film, the method comprising:

forming a layer including micro concave/convex portions on a surface of the layer, and forming said micro concave/convex portions by a shape transfer method, a sand blasting method, or a method of coating the surface with a resin containing fine particles,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

a value C(2.0) of transmitted image clarity measured by using an optical comb having a comb width of 2 mm in accordance with JIS-K7105 is equal to 30% or more, and

a ratio C(0.125)/C(2.0) of the value C(2.0) measured by using said optical comb having the comb width of 2 mm and a value C(0.125) measured by using an optical comb having a comb width of 0.125 mm is equal to 0.1 or more.

21. An anti-glare polarizer comprising:

a polarizer; and

an optical film formed on said polarizer,

wherein said optical film has micro concave/convex portions on a surface of the optical film,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

wherein when light incident on the optical film is reflected in a direction of specular reflection there is a deviation angle α from the direction of specular reflection at which a differentiation with respect to d{Log(I(α))}/dα is at a maximum absolute value, where Log(I(α)) represents a logarithm of an intensity of light reflected at the deviation angle α.

22. An anti-glare polarizer comprising

a polarizer; and

an optical film formed on said polarizer,

wherein said optical film has micro concave/convex portions on a surface of the optical film,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

a differentiation d{P(β)}/dβ of a histogram P(β) to an inclination angle β of said micro concave/convex portions has a maximum absolute value.

23. An anti-glare polarizer comprising:

a polarizer; and

an optical film formed on said polarizer,

wherein said optical film has micro concave/convex portions on a surface of the optical film,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

wherein a value C(2.0) of transmitted image clarity measured by using an optical comb having a comb width of 2 mm in accordance with JIS-K7105 is equal to 30% or more, and

wherein a ratio C(0.125)/C(2.0) of the value C(2.0) measured by using said optical comb having the comb width of 2 mm and a value C(0.125) measured by using an optical comb having a comb width of 0.125 mm is equal to 0.1 or more.

24. A display apparatus comprising:

a display unit displaying an image; and

an optical film formed on a display surface side of said display unit,

wherein said optical film has micro concave/convex portions on a surface of the optical film,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

wherein when light incident on the optical film is reflected in a direction of specular reflection there is a deviation angle α from the direction of specular reflection at which a differentiation with respect to d{Log(I(α))}/dα is at a maximum absolute value, where Log(I(α)) represents a logarithm of an intensity of light reflected at the deviation angle α.

25. A display apparatus comprising:

a display unit configured to display an image; and

an optical film formed on a display surface side of said display unit,

wherein said optical film has micro concave/convex portions on a surface of the optical film,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μm, and

wherein a differentiation d{P(β)}/dβ of a histogram P(β) to an inclination angle β of said micro concave/convex portions has an extreme value.

26. A display apparatus comprising:

a display unit configured to display an image; and

an optical film formed on a display surface side of said display unit,

wherein said optical film has micro concave/convex portions on a surface of the optical film,

wherein an average horizontal interval between minimum depths of the micro concave portions and maximum heights of the convex portions ranges from 5 to 300 μtm, and

wherein a value C(2.0) of transmitted image clarity measured by using an optical comb having a comb width of 2 mm in accordance with JIS-K7105 is equal to 30% or more, and

wherein a ratio C(0.125)/C(2.0) of the value C(2.0) measured by using said optical comb having the comb width of 2 mm and a value C(0.125) measured by using an optical comb having a comb width of 0.125 mm is equal to 0.1 or more.