Glass pane with reflectance reducing coating

• US 5,318,830 A
• Filed: 04/23/1992
• Issued: 06/07/1994
• Est. Priority Date: 05/29/1991
• Status: Expired due to Fees

• Current Assignee: Central Glass Company Limited
• Original Assignee: Central Glass Company Limited
• Inventors: Takamatsu, Atsushi, Makita, Kensuke
• Primary Examiner(s): Turner, A. A.
• Application Number:
  US07/872,033
• Time in Patent Office: 775 Days
• Field of Search: 428/212, 428/216, 428/336, 428/426, 428/428, 428/432, 428/697, 428/701, 428/702, 428/437, 359/359, 359/586, 359/589
• US Class Current: 428/216
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: B32B 17/10761 containing vinyl acetal
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/213 SiO2
• CPC Class Codes: C03C 2217/22 ZrO2
• CPC Class Codes: C03C 2217/23 Mixtures
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: C03C 2218/355 Temporary coating
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/3163 Next to acetal of polymerized unsaturated alcohol [e.g., formal butyral, etc.]

Abstract

The invention relates to a transparent coating on a transparent glass pane which may be a laminated glass pane such as an automobile windshield. The invention provides a two-layer coating made up of a first oxide film, e.g. a TiO₂ -SiO₂ mixed oxide film, which is in contact with the glass pane and has a thickness of 70-100 nm and a refractive index of 1.80-1.90 and an outer second oxide film, e.g. a SiO₂ film, which has a thickness of 110-130 nm and a refractive index of 1.40-1.50. With respect to visible light obliquely incident on the coating side of the glass pane at an angle of 50-70 degrees with the normal, the reflectance of the coated glass pane becomes lower than that of the glass pane without coating by 4.5-6.5%. To reduce the reflectance of perpendicularly incident light the two-layer coating can be modified into a three-layer coating by interposing another oxide film, e.g. a TiO₂ film, having a thickness of 130-160 nm and a refractive index of 2.05-2.30 between the above described first and second oxide films. The three-layer coating is nearly equivalent to the two-layer coating in the ability to reduce the reflectance of obliquely incident light.

Claims

1. A coated glass pane, comprising a transparent glass substrate and a reflectance reducing coating formed on a major surface of the glass substrate, the reflectance reducing coating being a two-layer coating comprising:

a first layer which is a transparent oxide film in direct contact with said major surface of said substrate and has a thickness of 70-100 nm and a refractive index in the range from 1.80 to 1.90, and

a second layer which is a transparent oxide film formed on said first layer and has a thickness of 110-130 nm and a refractive index in the range from 1.40 to 1.50,

said coating being constructed such that, with respect to visible light incident on said coating from the coated side of the coated glass pane at an incidence angle in the range from 50 to 70 degrees, the reflectance of the coated glass pane is lower than the reflectance of said glass substrate without coating by 4.5 to 6.5%;

wherein said first layer of said coating is a mixed oxide film comprising at least one relatively high refractivity oxide selected from the group consisting of TiO₂ and ZrO₂ and at least one relatively low refractivity oxide selected from the group consisting of SiO₂, Al₂ O₃ and B₂ O₃ ; and

wherein said second layer of said coating is a SiO₂ film.

2. A coated glass pane according to claim 1, wherein said first layer of said coating is a binary oxide film formed of TiO₂ and SiO₂.

3. A coated glass pane according to claim 2, wherein the molar ratio of said TiO₂ to said SiO₂ in said first layer is in the range from 55:

45 to 62;

38.

4. A coated glass pane according to claim 1, wherein said glass substrate comprises a color glass sheet.

5. A coated glass pane according to claim 1, wherein said glass substrate is a laminated glass pane.

6. A coated glass pane, comprising a transparent glass substrate and a reflectance reducing coating formed on a major surface of the glass substrate, the reflectance reducing coating being a three-layer coating comprising:

a first layer which is a transparent oxide film in direct contact with said major surface of said substrate and has a thickness of 70-100 nm and a refractive index in the range from 1.80 to 1.90,

a second layer which is a transparent oxide formed on said first layer and has a thickness of 130-160 nm and a refractive index in the range from 2.05 to 2.30, and

a third layer which is a transparent oxide film formed on said second layer and has a thickness of 110-130 nm and a refractive index in the range from 1.40 to 1.50,

said coating being constructed such that, with respect to visible light incident on said coating from the coated side of the coated glass pane at an incidence angle in the range from 50 to 70 degrees, the reflectance of the coated glass pane is lower than the reflectance of said glass substrate without coating by 4.5 to 6.5%;

wherein said first layer of said coating is a mixed oxide film comprising at least one relatively high refractivity oxide selected from the group consisting of TiO₂ and ZrO₂ and at least one relatively low refractivity oxide selected from the group consisting of SiO₂, Al₂ O₃ and B₂ O₃ ;

wherein said second layer of coating is a film comprising at least one member selected from the group consisting of TiO₂, Ta₂ O₅, and a combination of at least one member selected from the group consisting of TiO₂ and Ta₂ O₅ and at least one member selected from the group consisting of SiO₂, ZrO₂, Al₂ O₃ and B₂ O₃ ; and

wherein said third layer of said coating is a SiO₂ film.

7. A coated glass pane according to claim 6, wherein said glass substrate comprises a color glass sheet.

8. A coated glass pane according to claim 6, wherein said glass substrate is a laminated glass pane.

9. A coated glass pane, comprising a transparent glass substrate and a reflectance reducing coating formed on a major surface of the glass substrate, the reflectance reducing coating being a three-layer coating comprising:

a first layer which is a transparent oxide film in direct contact with said major surface of said substrate and has a thickness of 70-100 nm and a refractive index in the range from 1.80 to 1.90,

a second layer which is a transparent oxide film formed on said first layer and has a thickness of 130-160 nm and a refractive index in the range from 2.05 to 2.30, and

a third layer which is a transparent oxide film formed on said second layer and has a thickness of 110-130 nm and a refractive index in the range from 1.40 to 1.50,

said coating being constructed such that, with respect to visible light incident on said coating from the coated side of the coated glass pane at an incidence angle in the range from 50 to 70 degrees, the reflectance of the coated glass pane is lower than the reflectance of said glass substrate without coating by 4.5 to 6.5%,

wherein said first layer of said coating is a mixed oxide film comprising at least one relatively high refractivity oxide selected from the group consisting of TiO₂ and ZrO₂ and at least one relatively low refractivity oxide selected from the group consisting of SiO₂, Al₂ O₃ and B₂ O₃ ; and

said second layer of said coating is a film comprising at least one member selected from the group consisting of TiO₂, Ta₂ O₅, and a combination of at least one member selected from the group consisting of TiO₂ and Ta₂ O₅ and at least one member selected from the group consisting of SiO₂, ZrO₂, Al₂ O₃ and B₂ O₃.

10. A coated glass pane according to claim 9, wherein said first layer of said coating is a binary oxide film formed of TiO₂ and SiO₂.

11. A coated glass pane according to claim 10, wherein the molar ratio of said TiO₂ to said SiO₂ in said first layer is in the range from 55:

45 to 62;

38.

12. A coated glass pane according to claim 9, wherein said second layer of said coating is a TiO₂ film.

13. A coated glass pane according to claim 9, wherein said second layer of said coating is a Ta₂ O₅ film.

14. A coated glass pane according to claim 9, wherein said second layer of said coating is a binary oxide film formed of TiO₂ and Ta₂ O₅.

15. A coated glass pane according to claim 9, wherein said second layer of said coating is a mixed oxide film comprising at least one relatively high refractivity oxide selected from the group consisting of TiO₂ and Ta₂ O₅ and at least one relatively low refractivity oxide selected from the group consisting of SiO₂, ZrO₂, Al₂ O₃ and B₂ O₃.