OPTICAL SUBSTRATE

• US 20130271836A1
• Filed: 10/09/2012
• Published: 10/17/2013
• Est. Priority Date: 01/31/2012
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Topcon
• Original Assignee: Kabushiki Kaisha Topcon
• Inventors: FUKAYA, Hiroki, SHIMAMURA, Youichi, OKUBO, Takuro, ODAKA, Saki, SAITO, Takaaki, KOJIMA, Tatsuya
• Granted Patent: US 8,882,280 B2
• Time in Patent Office: Days
• US Class Current: 359/507
• CPC Class Codes: C03C 17/34 with at least two coatings having different compositions C03C17/44 takes precedence
• CPC Class Codes: C03C 17/3452 comprising a fluoride
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: G02B 1/105 Protective coatings
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• CPC Class Codes: G02B 1/113 using inorganic layer materials only
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 1/18 Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films G02B1/16 takes precedence
• CPC Class Codes: G02B 27/0006 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation G02B1/18 takes precedence; cleaning in general B08B
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361

Abstract

An optical substrate such as a cover glass which effects only a small change in a reflected color dependent on an incident angle, or more particularly, an optical substrate such as a cover glass for displays includes a reinforcement layer intended to prevent cracking, an antiglare layer formed on the reinforcement layer, a tone-adjustment antireflection film formed on the antiglare layer, and an antifouling layer formed on the antireflection film intended to minimize fingerprint adhesion. The antireflection film includes at least nine layers.

Claims

1. An optical substrate comprising:

a tone-adjustment antireflection film; and

an antifouling layer formed on the antireflection film in order to minimize fingerprint adhesion, wherein

the antireflection film includes at least nine layers.

4. The optical substrate according to claim 1, wherein:

the antireflection film is made of a high-refractive index material of Nb₂O₅, Ta₂O₅, TiO₂, or ZrO₂, or a mixture material using any of these materials, and a low-refractive index material of SiO₂ or MgF₂; and

assuming that nh denotes the refractive index of the high-refractive index material, nl denotes the refractive index of the low-refractive index material, and Δ

n denotes a difference between the refractive indices nh and nl of adjoining layers, the antireflection film satisfies conditions (1) to (3) below.

nh≦

2.0  

 

(1)

nl≦

1.60  

 

(2)

Δ

n≦

0.30  

 

(3)

5. The optical substrate according to claim 1, wherein:

the antireflection film includes nine layers;

assuming that n1, n2, n3, n4, n5, n6, n7, n8, and n9 denote the refractive indices of the nine layers beginning with a layer on an extremely medium side of the antireflection film, and d1, d2, d3, d4, d5, d6, d7, d8, and d9 denote the optical film thicknesses of the respective layers beginning with the layer on the extremely medium side, the antireflection film satisfies conditions below.

n2≦

1.40  

 

(a)

n3=n5=n7=n9>

n1=n4=n6=n8>

n2  

 

(b)

0.0225λ

0≦

d1≦

0.0525λ

0  

 

(c)

0.1453λ

0≦

d2≦

0.3389λ

0  

 

(d)

0.0733λ

0≦

d3≦

0.1710λ

0  

 

(e)

0.0307λ

0=d4≦

0.0716λ

0  

 

(f)

0.2096λ

0≦

d4≦

0.4892λ

0  

 

(g)

0.0315λ

0≦

d6≦

0.0735λ

0  

 

(h)

0.0810λ

0≦

d7≦

0.1889λ

0  

 

(i)

0.0798λ

0≦

d8≦

0.1863λ

0  

 

(j)

0.0258λ

0≦

d9≦

0.0602λ

0  

 

(k)

6. The optical substrate according to claim 1, wherein the superficial layer and second layer of the antireflection film contain at least one material selected from a group including silicon oxide and magnesium fluoride.

7. The optical substrate according to claim 1, wherein the antireflection film is used for visible rays whose wavelengths range from 390 nm to 800 nm.

8. The optical substrate according to claim 1, wherein the spectral reflectance of the antireflection film is equal to or lower than 1.0% with respect to a wavelength range from 390 nm to 800 nm, and equal to or lower than 0.5% with respect to a wavelength range from 400 nm to 780 nm.

9. The optical substrate according to claim 1, wherein when a D65 white light source is used, a* and b* values in the CIELAB color space expressing the reflected color of an antireflection film employed meet −

5<

a*<

5 and −

5<

b*<

5 respectively.

10. The optical substrate according to claim 1, wherein the antifouling layer includes a water-repellent and oil-repellent film.

2. An optical substrate comprising:

a reinforcement layer intended to prevent cracking;

a tone-adjustment antireflection film formed on the reinforcement layer; and

an antifouling layer formed on the antireflection film in order to minimize fingerprint adhesion, wherein

the antireflection film includes at least nine layers.

11. The optical substrate according to claim 2, wherein:

the antireflection film is made of a high-refractive index material of Nb₂O₅, Ta₂O₅, TiO₂, or ZrO₂, or a mixture material using any of these materials, and a low-refractive index material of SiO₂ or MgF₂; and

assuming that nh denotes the refractive index of the high-refractive index material, nl denotes the refractive index of the low-refractive index material, and Δ

n denotes a difference between the refractive indices nh and nl of adjoining layers, the antireflection film satisfies conditions (1) to (3) below.

nh≧

2.0  

 

(1)

nl≦

1.60  

 

(2)

Δ

n≧

0.30  

 

(3)

13. The optical substrate according to claim 2, wherein:

the antireflection film includes nine layers;

assuming that n1, n2, n3, n4, n5, n6, n7, n8, and n9 denote the refractive indices of the nine layers beginning with a layer on an extremely medium side of the antireflection film, and d1, d2, d3, d4, d5, d6, d7, d8, and d9 denote the optical film thicknesses of the respective layers beginning with the layer on the extremely medium side, the antireflection film satisfies conditions below.

n2≦

1.40  

 

(a)

n3=n5=n7=n9>

n1=n4=n6=n8>

n2  

 

(b)

0.0225λ

0≦

d1≦

0.0525λ

0  

 

(c)

0.1453λ

0≦

d2≦

0.3389λ

0  

 

(d)

0.0733λ

0≦

d3≦

0.1710λ

0  

 

(e)

0.0307λ

0=d4≦

0.0716λ

0  

 

(f)

0.2096λ

0≦

d4≦

0.4892λ

0  

 

(g)

0.0315λ

0≦

d6≦

0.0735λ

0  

 

(h)

0.0810λ

0≦

d7≦

0.1889λ

0  

 

(i)

0.0798λ

0≦

d8≦

0.1863λ

0  

 

(j)

0.0258λ

0≦

d9≦

0.0602λ

0  

 

(k)

15. The optical substrate according to claim 2, wherein the superficial layer and second layer of the antireflection film contain at least one material selected from a group including silicon oxide and magnesium fluoride.

17. The optical substrate according to claim 2, wherein the antireflection film is used for visible rays whose wavelengths range from 390 nm to 800 nm.

19. The optical substrate according to claim 2, wherein the spectral reflectance of the antireflection film is equal to or lower than 1.0% with respect to a wavelength range from 390 nm to 800 nm, and equal to or lower than 0.5% with respect to a wavelength range from 400 nm to 780 nm.

3. An optical substrate comprising:

a reinforcement layer intended to prevent cracking;

an antiglare layer formed on the reinforcement layer;

a tone-adjustment antireflection film formed on the antiglare layer; and

an antifouling layer formed on the antireflection film in order to minimize fingerprint adhesion, wherein

the antireflection film includes at least nine layers.

12. The optical substrate according to claim 3, wherein:

the antireflection film is made of a high-refractive index material of Nb₂O₅, Ta₂O₅, TiO₂, or ZrO₂, or a mixture material using any of these materials, and a low-refractive index material of SiO₂ or MgF₂; and

assuming that nh denotes the refractive index of the high-refractive index material, nl denotes the refractive index of the low-refractive index material, and Δ

n denotes a difference between the refractive indices nh and nl of adjoining layers, the antireflection film satisfies conditions (1) to (3) below.

nh≧

2.0  

 

(1)

nl≦

1.60  

 

(2)

Δ

n≧

0.30  

 

(3)

14. The optical substrate according to claim 3, wherein:

the antireflection film includes nine layers;

assuming that n1, n2, n3, n4, n5, n6, n7, n8, and n9 denote the refractive indices of the nine layers beginning with a layer on an extremely medium side of the antireflection film, and d1, d2, d3, d4, d5, d6, d7, d8, and d9 denote the optical film thicknesses of the respective layers beginning with the layer on the extremely medium side, the antireflection film satisfies conditions below.

n2≦

1.40  

 

(a)

n3=n5=n7=n9>

n1=n4=n6=n8>

n2  

 

(b)

0.0225λ

0≦

d1≦

0.0525λ

0  

 

(c)

0.1453λ

0≦

d2≦

0.3389λ

0  

 

(d)

0.0733λ

0≦

d3≦

0.1710λ

0  

 

(e)

0.0307λ

0=d4≦

0.0716λ

0  

 

(f)

0.2096λ

0≦

d4≦

0.4892λ

0  

 

(g)

0.0315λ

0≦

d6≦

0.0735λ

0  

 

(h)

0.0810λ

0≦

d7≦

0.1889λ

0  

 

(i)

0.0798λ

0≦

d8≦

0.1863λ

0  

 

(j)

0.0258λ

0≦

d9≦

0.0602λ

0  

 

(k)

16. The optical substrate according to claim 3, wherein the superficial layer and second layer of the antireflection film contain at least one material selected from a group including silicon oxide and magnesium fluoride.

18. The optical substrate according to claim 3, wherein the antireflection film is used for visible rays whose wavelengths range from 390 nm to 800 nm.

20. The optical substrate according to claim 3, wherein the spectral reflectance of the antireflection film is equal to or lower than 1.0% with respect to a wavelength range from 390 nm to 800 nm, and equal to or lower than 0.5% with respect to a wavelength range from 400 nm to 780 nm.