Method of producing anti-reflection film

• US 7,351,447 B2
• Filed: 03/19/2004
• Issued: 04/01/2008
• Est. Priority Date: 10/12/2001
• Status: Expired due to Fees

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Kato, Nobuko, Kusano, Yukihiro, Nishida, Mitsuhiro
• Primary Examiner(s): Bashore; Alain L.
• Application Number:
  US10/804,073
• Publication Number:
  US 20040180138A1
• Time in Patent Office: 1,474 Days
• Field of Search: 427/162, 427/164, 427/419.1, 428/212, 428/702, 428/328, 428/331
• US Class Current: 427/162
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: G02B 1/116 including electrically conducting layers
• CPC Class Codes: G02B 1/16 having an anti-static effect, e.g. electrically conducting coatings
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/259 Silicic material

Abstract

A method of producing an anti-reflection film includes forming a first layer on a transparent substrate, forming a second layer on the first layer, and forming the third layer on the second layer. When an optical admittance Y at a surface of the second layer is represented by,

$Y=\frac{H}{E}=\left(x+\mathrm{iy}\right)$
where i is the imaginary number unit,
thicknesses and reflective indexes of the substrate, first layer, second layer, and third layer are selected so that x and y satisfy the following formula,
0.9x{(n²−n₀²)/2n₀}²<{x−(n²+n₀²)/2n₀}²+y²<1.1x{(n²−n₀²)/2n₀}²
where n is a refractive index of the third layer and n₀ is a refractive index of an outer region at an outside of the anti-reflection film.

Claims

1. A method of producing an anti-reflection film, comprising:

selecting a first material having a-reflective index of n₁,

coating the first material on a transparent substrate having a reflective index of n_s to form a first layer having a thickness of d₁,

selecting a second material having a reflective index of n₂,

coating the second material on the first layer to form a second layer having a thickness of d₂ so that an optical admittance Y at a surface of the second layer opposite to the first layer is represented by,

2. A method of producing an anti-reflection film according to claim 1, wherein said third layer is formed so that an optical admittance Y_e at a surface of the third layer opposite to the second layer is represented by,

$Y_e=\frac{H_e}{E_e}$

[EeHe]=[cos⁢

⁢

δ

3(i/n3)⁢

⁢

sin⁢

⁢

δ

3i⁢

⁢

n3⁢

⁢

sin⁢

⁢

δ

3cos⁢

⁢

δ

3]⁡

[cos⁢

⁢

δ

2(i/n2)⁢

⁢

sin⁢

⁢

δ

2i⁢

⁢

n2⁢

⁢

sin⁢

⁢

δ

2cos⁢

⁢

δ

2]⁢

⁢

[cos⁢

⁢

δ

1(i/n1)⁢

sin⁢

⁢

δ

1i⁢

⁢

n1⁢

sin⁢

⁢

δ

1cos⁢

⁢

δ

1]⁡

[1ns]
δ

₃=2bπ

n₃d₃/λ

₀

said thickness of the third layer being selected so that E_e is substantially equal to 1 and H_e is substantially equal to n₀.

3. A method of producing an anti-reflection film according to claim 1, further comprising forming at least one additional j-th layer having a reflective index of n_j and a thickness of d_j on the transparent substrate before forming the first layer where j is a natural number at least 4 so that an optical admittance Y′

at the surface of the second layer opposite to the first layer is represented by,

$Y^{\mathrm{\prime <br><br>}}=\frac{H^{\mathrm{\prime <br><br>}}}{E^{\mathrm{\prime <br><br>}}}=\left(x^{\mathrm{\prime <br><br>}}+{\mathrm{iy}}^{\mathrm{\prime <br><br>}}\right)<br><br>[<br><br>\begin{array}{c}{E}^{\mathrm{\prime <br><br>}}\\ H^{\mathrm{\prime <br><br>}}\end{array}]=\left[\begin{array}{cc}\cos <br><br><br><br>{\mathrm{\delta <br><br>}}_2& \left(i/n_2\right)<br><br><br><br>\sin <br><br><br><br>{\mathrm{\delta <br><br>}}_2\\ i<br><br><br><br>n_2<br><br><br><br>\sin <br><br><br><br>{\mathrm{\delta <br><br>}}_2& \cos <br><br><br><br>{\mathrm{\delta <br><br>}}_2\end{array}\right][<br><br>\begin{array}{cc}\cos <br><br><br><br>{\mathrm{\delta <br><br>}}_1& \left(i/n_1\right)<br><br>\sin <br><br><br><br>{\mathrm{\delta <br><br>}}_1\\ i<br><br><br><br>n_1<br><br>\sin <br><br><br><br>{\mathrm{\delta <br><br>}}_1& \cos <br><br><br><br>{\mathrm{\delta <br><br>}}_1\end{array}]<br><br><br><br>[<br><br>\begin{array}{cc}\cos <br><br><br><br>{\mathrm{\delta <br><br>}}_j& \left(i/n_j\right)<br><br>\sin <br><br><br><br>{\mathrm{\delta <br><br>}}_j\\ i<br><br><br><br>n_j<br><br>\sin <br><br><br><br>{\mathrm{\delta <br><br>}}_j& \cos <br><br><br><br>{\mathrm{\delta <br><br>}}_j\end{array}<br><br>]<br><br><br><br>\mathrm{\dots <br><br>}<br><br>\left[\begin{array}{c}1\\ n_s\end{array}\right]$
δ

_j=2π

n_jd_j/λ

₀

wherein said reflective index of the transparent substrate, the reflective index and the thickness of the first layer, the reflective index and the thickness of the second layer, the reflective index of the third layer, and the reflective index and the thickness of the at least one additional j-th layer are selected so that x′ and

y′

satisfy the following formula,

0.9x{(n₃²−

n₀²)/2n₀}²<

{x′

−

(n₃²+n₀²)/2n₀}²+y′

²<

1.1x{(n₃²−

n₀²)/2n₀}²

4. A method of producing an anti-reflection film according to claim 3, wherein said third layer is formed so that an optical admittance Y′

_e at the surface of the third layer opposite to the second layer is represented by,

5. A method of producing an anti-reflection film according to claim 1, wherein said third layer has an attenuation coefficient of substantially zero.

6. A method of producing an anti-reflection film according to claim 1, wherein said second layer has an attenuation coefficient more than 0.001 at a wavelength of 550 nm.

7. A method of producing an anti-reflection film according to claim 1, wherein said second layer has an attenuation coefficient between 0.01 and 10 at a wavelength of 550 nm.

8. A method of producing an anti-reflection film according to claim 1, wherein said transparent substrate is formed of a synthetic resin.

9. A method of producing an anti-reflection film according to claim 1, wherein said second layer is formed of a composite material containing fine particles of at least one selected from the group consisting of metal, metal oxide and metal nitride.

10. A method of producing an anti-reflection film according to claim 1, wherein said second layer is a thin film formed of at least one selected from the group consisting of metal, metal oxide and metal nitride.

11. A method of producing an anti-reflection film according to claim 1, wherein said second layer has a thickness smaller than 30 nm.

12. A method of producing an anti-reflection film according to claim 1, wherein said transparent substrate is formed of polyester.

13. A method of producing an anti-reflection film according to claim 1, wherein said transparent substrate has a thickness between 30 to 300 μ

m.