Electronic devices having scratch-resistant antireflection coatings

Patent metadata

Field	Value
Publication number	US-10591645-B2
Application number	US-201715484888-A
Country	US
Kind code	B2
Filing date	Apr 11, 2017
Priority date	Sep 19, 2016
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

An electronic device may have transparent members such as display cover layers and camera windows. A transparent member such as a sapphire member may be provided with an antireflection coating. The antireflection coating may have a stack of dielectric thin-film interference filter layers that form a thin-film interference filter that suppresses visible light reflections. The stack of dielectric thin-film interference filter layers may have thicknesses and materials that provide the thin-film interference filter and coating with low light reflection properties while enhancing scratch resistance. An adhesion layer may be used to help adhere the stack of thin-film interference filter layer to the transparent member. An antismudge coating such as a fluoropolymer coating may be used to reduce smudging. Graded layers and layers with elevated hardness values may be used in the coating.

First claim

What is claimed is:

1. An electronic device having an interior and an exterior, comprising:
a housing;
a component in the housing;
a transparent member that overlaps the component and that separates the interior of the electronic device from the exterior of the electronic device, wherein the transparent member has a first surface that faces the exterior and an opposing second surface;
a visible light antireflection coating on the first surface of the transparent member that includes a stack of thin-film interference filter layers including an uppermost thin-film interference filter layer having a first index of refraction, a lowermost thin-film interference filter layer between the uppermost thin-film interference filter layer and the transparent member, and a second-to-top thin-film interference filter layer that is adjacent to the uppermost thin-film inference filter layer and that has a second index of refraction that is lower than the first index of refraction; and
an adhesion layer between the lowermost thin-film-interference filter layer and the transparent member, wherein the adhesion layer comprises a graded index layer.

2. The electronic device defined in claim 1 further comprising an antismudge layer on the uppermost thin-film interference filter layer.

3. The electronic device defined in claim 2 wherein the uppermost thin-film interference filter layer comprises a layer selected from the group consisting of: a silicon nitride layer, a hafnium oxide layer, and a diamond-like carbon layer.

4. The electronic device defined in claim 3 wherein the second-to-top thin-film interference filter layer is a silicon oxide layer.

5. The electronic device defined in claim 4 wherein the transparent member comprises a sapphire member and wherein the uppermost thin-film interference filter layer has a thickness of less than 20 nm.

6. The electronic device defined in claim 1 wherein the component comprises a camera.

7. The electronic device defined in claim 1 wherein the graded index layer comprises a mixture of aluminum oxide and silicon oxide.

8. The electronic device defined in claim 7 wherein the lowermost thin-film interference filter layer comprises a silicon oxide layer.

9. The electronic device defined in claim 1 wherein the lowermost thin-film interference filter is formed on the transparent member and comprises a first material and wherein the uppermost thin-film interference filter comprises a second material that is the same as the first material.

10. The electronic device defined in claim 1 wherein the adhesion layer has opposing first and second surfaces, wherein the first surface contacts the transparent member, and wherein the second surface contacts the lowermost thin-film interference filter layer.

11. An electronic device, comprising:
a camera;
a transparent sapphire member that overlaps the camera; and
a visible light antireflection coating on the sapphire member that includes a stack of thin-film interference filter layers including an uppermost thin-film interference filter layer having a first index of refraction, wherein the uppermost thin-film interference filter layer has an index of refraction of greater than 2.0, a lowermost thin-film interference filter layer between the uppermost thin-film interference filter layer and the transparent sapphire member, a second-to-top thin-film interference filter layer that is adjacent to the uppermost thin-film interference filter layer and that has a second refractive index that is lower than the first index of refraction, wherein the uppermost thin-film interference filter layer comprises the same material as at least one of the other thin-film interference filter layers, wherein each filter layer of the stack of thin-film interference filter layers has an individual thickness, and wherein the individual thickness of the uppermost thin-film interference filter layer is less than all of the other individual thicknesses of the thin-film interference filter layers.

12. The electronic device defined in claim 11 further comprising an antismudge layer on the uppermost thin-film interference filter layer, wherein the uppermost thin-film interference filter has a Knoop hardness of at least 1500.

13. The electronic device defined in claim 11 wherein the stack of thin-film interference filter layers comprises a plurality of silicon oxide layers and wherein the uppermost thin-film interference filter layer comprises a layer selected from the group consisting of: titanium dioxide, niobium oxide, tantalum oxide, zirconium oxide, hafnium oxide, silicon nitride, and yttrium oxide, aluminum oxide, and aluminum nitride.

14. An electronic device, comprising:
a light-based component;
a transparent member that overlaps the light-based component;
a visible light antireflection coating on the transparent member that includes a stack of thin-film interference filter layers including an uppermost thin-film interference filter layer and a lowermost thin-film interference filter layer between the uppermost thin-film interference filter layer and the transparent member, wherein the uppermost thin-film interference filter layer has first and second opposing surfaces, wherein the first surface of the uppermost thin-film interference filter layer is coupled to an underlying thin-film interference filter layer, and wherein the uppermost thin-film interference filter layer is a graded index layer having a first refractive index at the first surface; and
a fluoropolymer antismudge layer on the second surface of the uppermost thin-film interference filter layer, wherein the uppermost thin-film interference filter layer has a second refractive index at the second surface that is higher than the first refractive index.

15. The electronic device defined in claim 14 wherein the uppermost thin-film interference filter layer comprises a mixture of first and second materials and wherein the first material is silicon nitride.

16. The electronic device defined in claim 15 wherein the light-based component comprises an image sensor.

17. The electronic device defined in claim 14 , wherein the transparent member comprises a sapphire member, wherein the visible light antireflection coating further comprises a graded index adhesion layer between the lowermost thin-film interference filter layer and the sapphire member, wherein the graded index adhesion layer includes a mixture of first and second materials, and wherein the first material comprises aluminum oxide.

18. The electronic device defined in claim 14 wherein the uppermost thin-film interference filter layer comprises a first material having a first hardness and a second material having a second hardness that is greater than the first hardness, wherein the first surface is formed from the first material, and wherein the second surface is formed from the second material.

Assignees

• Apple Inc

Inventors

• Ge Zhenbin
• Zhao Xianwei
• Bae Wookyung
• Kang Sunggu
• Wang Ligang
• Yuen Avery P
• Cool Stephen C
• Zhong John Z

Classifications

• G02B1/14

  Protective coatings, e.g. hard coatings · CPC title

• G02B1/18

  Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films (G02B1/16 takes precedence) · CPC title

• G02B1/115 Primary

  Multilayers · CPC title

• G02B5/28

  Interference filters · CPC title