Touch sensor panel having an index matching passivation layer

• US 10,558,281 B2
• Filed: 07/13/2015
• Issued: 02/11/2020
• Est. Priority Date: 11/11/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Tung, Chun-Hao, Dorjgotov, EnkhAmgalan, Kuwabara, Masato, Kang, Sunggu, Chen, Cheng, Zhong, John Z.
• Primary Examiner(s): Edouard, Patrick N
• Assistant Examiner(s): Wilson, Douglas M
• Application Number:
  US14/798,417
• Publication Number:
  US 20150316689A1
• Time in Patent Office: 1,674 Days
• CPC Class Codes: B32B 2457/208 Touch screens
• CPC Class Codes: B32B 37/12 characterised by using adhesives
• CPC Class Codes: G02B 1/11 Anti-reflection coatings
• CPC Class Codes: G02B 1/111 using layers comprising organic materials
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

Touch sensor panels typically include a plurality of layers that can be stacked on top of each other. When the touch sensor panel is used in a bright environment, incident light can hit the interfaces between those layers of the stackup having mismatched refractive indices and can reflect off those interfaces. The light reflected from those interfaces can give rise to the appearance of fringes on the touch sensor panel, which can be visually distracting. In order to reduce the appearance of these fringes, embodiments of the disclosure are directed to the addition of an index matching passivation layer between a conductive layer of traces and an adhesive layer in the touch sensor panel stackup.

Claims

1. A stackup for contacting a touch sensor panel adhesive layer and conductive material layer, comprising:

a first index matching passivation layer configured for contacting the adhesive layer at a first interface; and

a second index matching passivation layer adjacent to the first index matching passivation layer and configured for contacting the conductive material layer at a second interface;

wherein the first index matching passivation layer is selected to have a first refractive index to produce a percentage reflectance at the first interface of less than 1%; and

wherein the second index matching passivation layer is selected to have a second refractive index to produce a percentage reflectance at the second interface of less than 1%.

2. The stackup of claim 1, wherein the second index matching passivation layer is configured for contacting the conductive material layer when the conductive material layer is formed from Indium Tin Oxide (ITO).

3. The stackup of claim 1, wherein the second refractive index is between 1.6 and 1.75.

4. The stackup of claim 1, wherein the first index matching passivation layer is selected with the first refractive index and the second index matching passivation layer is selected with the second refractive index to create a first percentage reflectance at the first interface and a second percentage reflectance at the second interface, the first percentage reflectance and the second percentage reflectance having a predetermined relationship.

5. The stackup of claim 4, wherein the first percentage reflectance and the second percentage reflectance are approximately equal.

6. The stackup of claim 5, wherein the first and second index matching passivation layers have a combined total refractive index of about 1.65.

7. The stackup of claim 1, the second index matching passivation layer formed from a combination of acrylic material and ZrO₂.

8. The stackup of claim 1, the second index matching passivation layer formed from a combination of acrylic material and a second material selected from the group consisting of TiO₂ (Rutile), TiO₂ (Anatase) and ZnO.

9. The stackup of claim 1, the first and second index matching passivation layers having a combined thickness of between 2 and 15 um.

10. The stackup of claim 1, further comprising the adhesive layer, wherein the adhesive layer is in contact with the first index matching passivation layer.

11. A stackup for contacting a touch sensor panel adhesive layer and conductive material layer, comprising:

a first index matching passivation layer configured for contacting the adhesive layer at a first interface; and

a second index matching passivation layer adjacent to the first index matching passivation layer and configured for contacting the conductive material layer at a second interface;

wherein the first index matching passivation layer is selected to have a first refractive index and the second index matching passivation layer is selected to have a second refractive index to create a first percentage reflectance at the first interface and a second percentage reflectance at the second interface, the first percentage reflectance and the second percentage reflectance being approximately equal.

12. The stackup of claim 11, wherein the second index matching passivation layer is configured for contacting the conductive material layer when the conductive material layer is formed from Indium Tin Oxide (ITO).

13. The stackup of claim 11, wherein the second refractive index is about 1.65.

14. The stackup of claim 11, wherein the first index matching passivation layer is selected with the first refractive index to produce the percentage reflectance at the first interface of less than 1%, and the second index matching passivation layer is selected with the second refractive index to produce the percentage reflectance at the second interface of less than 1%.

15. The stackup of claim 11, the second index matching passivation layer formed from a combination of acrylic material and ZrO₂.

16. The stackup of claim 11, the second index matching passivation layer formed from a combination of acrylic material and a second material selected from the group consisting of TiO₂ (Rutile), TiO₂ (Anatase) and ZnO.

17. The stackup of claim 11, the first and second index matching passivation layers having a combined thickness of between 2 and 15 um.

18. The stackup of claim 11, further comprising the adhesive layer, wherein the adhesive layer is in contact with the first index matching passivation layer.

19. A method of reducing an appearance of fringes on a touch sensor panel, comprising:

forming a first index matching passivation layer for contacting an adhesive layer at a first interface;

forming a second index matching passivation layer adjacent to the first index matching passivation layer, the second index matching layer for contacting a conductive material layer at a second interface;

selecting the first index matching passivation layer with a first refractive index to produce a percentage reflectance at the first interface of less than 1%; and

selecting the second index matching passivation layer with a second refractive index to produce a percentage reflectance at the second interface of less than 1%.

20. The method of claim 19, further comprising forming the second index matching passivation layer for contacting the conductive material layer when the conductive material layer is formed from Indium Tin Oxide (ITO).

21. The method of claim 19, further comprising forming the second index matching passivation layer such that the second refractive index is between 1.6 and 1.75.

22. The method of claim 19, further comprising selecting the first and second index matching passivation layers to create a first percentage reflectance at the first interface and a second percentage reflectance at the second interface, the first percentage reflectance and the second percentage reflectance being approximately equal.

23. The method of claim 22, further comprising forming the first and second index matching passivation layers to have a combined total refractive index of about 1.65.

24. The method of claim 19, further comprising forming the second index matching passivation layer from a combination of acrylic material and ZrO₂.

25. The method of claim 19, further comprising forming the first and second index matching passivation layers to have a combined thickness of between 2 and 15 um.