Touch screen having reduced visibility transparent conductor pattern

• US 8,264,466 B2
• Filed: 03/31/2006
• Issued: 09/11/2012
• Est. Priority Date: 03/31/2006
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Maag, Jonathan P., Aufderheide, Brian E., Spang, Joseph C.
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): Lubit, Ryan A
• Application Number:
  US11/278,166
• Publication Number:
  US 20070236618A1
• Time in Patent Office: 2,356 Days
• Field of Search: 345173-179, 345/182, 345/183, 345204-215, 345690-699
• US Class Current: 345/173
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• 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: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

Disclosed is a transparent touch screen construction that includes a pattern of layer stacks disposed on a substrate. The layer stacks each include a transparent conductor layer and an intermediate layer positioned between the substrate and the transparent conductor layer. The intermediate layer has a refractive index that is lower than that of the transparent conductor layer and that of the substrate. The construction of the layer stacks reduces the difference in visible light transmission between the areas of the substrate covered by the stacks and the areas of the substrate left exposed by the stacks. Also disclosed are methods for reducing the visibility of a patterned transparent conductor in a touch screen by disposing an intermediate layer pattern between a substrate and a transparent conductor pattern, the intermediate layer pattern and transparent conductor pattern being coincident.

Claims

1. A transparent touch screen construction, comprising:

a substrate;

a plurality of layer stacks disposed on the substrate leaving areas of the substrate exposed and areas of the substrate covered by the stacks, each layer stack comprising a transparent conductor layer and an intermediate layer, the intermediate layer having a first major surface in contact with the substrate and a second major surface in contact with the transparent conductor layer, the intermediate layer having an index of refraction that is less than that of the transparent conductor layer and less than that of the substrate;

a plurality of lead lines electrically connected to the transparent conductor layers and configured for connecting to controller electronics adapted to determine touch input information based on signals received when a touch input is coupled to the transparent conductors; and

an adhesive layer disposed on the transparent conductor layer of each layer stack in the areas covered by the stacks, the adhesive layer also being disposed on the substrate in the areas exposed by the stacks, the adhesive layer having a different material composition than the intermediate layer;

wherein a thickness of the transparent conductor layer and a thickness of the intermediate layer are tailored to provide a difference in visible light transmission through the areas covered by the stacks and the areas exposed by the stacks that has a maximum over a range from 400 to 700 nm of about 1% or less and an average over the 400 to 700 nm range of about 0.5% or less.

2. The transparent touch screen construction of claim 1, wherein the substrate is plastic.

3. The transparent touch screen construction of claim 1, wherein the substrate is PET.

4. The transparent touch screen construction of claim 1, wherein the intermediate layer is silicon oxide.

5. The transparent touch screen construction of claim 1, wherein the transparent conductor layer is indium tin oxide.

6. The transparent touch screen construction of claim 1, wherein the substrate is a first substrate and the adhesive layer is an optical adhesive layer, and further comprising a second substrate having an interior surface attached to the optical adhesive layer and an exterior surface opposing the interior surface.

7. The transparent touch screen construction of claim 6, wherein the second substrate is PET.

8. The transparent touch screen construction of claim 6, wherein the second substrate is glass.

9. The transparent touch screen construction of claim 6, wherein the second substrate further comprises a plurality of touch sensitive elements arranged in a pattern.

10. The transparent touch screen construction of claim 1, wherein each of the areas covered by the stacks has a visible light transmission that changes by no more than about 1% over the range from 400 to 700 nm, and wherein each of the areas exposed by the stacks has a visible light transmission that changes by no more than about 1% over the range from 400 to 700 nm.

11. A transparent touch screen construction, comprising:

a substrate;

a plurality of layer stacks disposed on the substrate leaving areas of the substrate exposed and areas of the substrate covered by the stacks, each layer stack comprising a transparent conductor layer and an intermediate layer, the intermediate layer having a first major surface in contact with the substrate and a second major surface in contact with the transparent conductor layer, the intermediate layer having an index of refraction that is less than that of the transparent conductor layer and less than that of the substrate, each stack further comprising an overlayer in contact with the transparent conductor layer so that the transparent conductor layer resides between the intermediate layer and the overlayer, the overlayer also being disposed on the substrate in the areas exposed by the stacks, the overlayer having an index of refraction that is less than that of the transparent conductor layer;

a plurality of lead lines electrically connected to the transparent conductor layers and configured for connecting to controller electronics adapted to determine touch input information based on signals received when a touch input is coupled to the transparent conductors;

an adhesive layer disposed on the transparent conductor layer disposed on the overlayer of each layer stack in the areas covered by the stacks, the adhesive layer also being disposed on the substrate in the areas exposed by the stacks, the adhesive layer having a different material composition than the intermediate layer;

wherein a thickness of the transparent conductor layer and a thickness of the intermediate layer are tailored to provide a difference in visible light transmission through the areas covered by the stacks and the areas exposed by the stacks that has a maximum over a range from 400 to 700 nm of about 1% or less and an average over the 400 to 700 nm range of about 0.5% or less.

12. The transparent touch screen construction of claim 11, wherein the substrate is plastic, and the transparent conductor layer is indium tin oxide.

13. The transparent touch screen construction of claim 12, wherein the substrate has a refractive index of about 1.6 to 1.7, the intermediate layer has a refractive index of about 1.4 to 1.6, the transparent conductor layer has a refractive index of about 1.8 to 2.1, and the adhesive layer is an optical adhesive layer having a refractive index of about 1.4 to 1.8.

14. The transparent touch screen construction of claim 11, wherein the substrate has a refractive index of about 1.6 to 1.7, the intermediate layer has a refractive index of about 1.4 to 1.6, the transparent conductor layer has a refractive index of about 1.8 to 2.1, and the adhesive layer is an optical adhesive layer having a refractive index of about 1.4 to 1.8.

15. The transparent touch screen construction of claim 11, wherein the substrate is a first substrate and the adhesive layer is an optical adhesive layer, and further comprising a second substrate having an interior surface attached to the optical adhesive layer and an exterior surface opposing the interior surface.

16. The transparent touch screen construction of claim 15, wherein the second substrate is PET.

17. The transparent touch screen construction of claim 15, wherein the second substrate is glass.

18. The transparent touch screen construction of claim 15, wherein the second substrate further comprises a plurality of touch sensitive elements arranged in a pattern.

19. The transparent touch screen construction of claim 18, wherein the plurality of touch sensitive elements of the second substrate have a layer construction that is the same as the plurality of layer stacks of the first substrate.

20. The transparent touch screen construction of claim 11, wherein each of the areas covered by the stacks has a visible light transmission that changes by no more than about 1% over the range from 400 to 700 nm, and wherein each of the areas exposed by the stacks has a visible light transmission that changes by no more than about 1% over the range from 400 to 700 nm.

21. A method for reducing the visibility of a patterned transparent conductor in a touch screen, comprising:

providing a substrate covered with a transparent conductor layer and an intermediate layer, the intermediate layer having a first major surface in contact with the substrate and a second major surface in contact with the transparent conductor layer, the intermediate layer having an index of refraction that is less than that of the transparent conductor layer and less than that of the substrate;

patterning the transparent conductor layer; and

patterning the intermediate layer to coincide with the patterned transparent conductor layer to provide a plurality of layer stacks on the substrate leaving areas of the substrate exposed by the stacks and areas of the substrate covered by the stacks; and

disposing an adhesive material over the plurality of layer stacks such that the adhesive material covers both the areas of the substrate covered by the stacks and the areas of the substrate exposed by the stacks, the adhesive material having an index of refraction that is less than that of the patterned transparent conductor layer, the adhesive material also having a different material composition than the intermediate layer;

wherein the patterning is carried out and thicknesses of the intermediate layer and the patterned transparent conductor are tailored such that a difference in visible light transmission through the areas covered by the stacks and the areas exposed by the stacks has a maximum over a range from 400 to 700 nm of about 1% or less and an average over the 400 to 700 nm range of about 0.5% or less.

22. The method of claim 21, wherein the adhesive material comprises an optical adhesive.

23. The method of claim 22, further comprising the step of disposing a second substrate over the adhesive material.

24. The method of claim 21, wherein the steps of patterning the transparent conductor layer and patterning the intermediate layer occur simultaneously.

25. The method of claim 21, wherein the step of patterning the intermediate layer occurs prior to the step of patterning the transparent conductor layer.

26. The method of claim 21, wherein the patterning is carried out and thicknesses of the intermediate layer and the patterned transparent conductor are tailored such that each of the areas covered by the stacks has a visible light transmission that changes by no more than about 1% over the range from 400 to 700 nm, and wherein each of the areas exposed by the stacks has a visible light transmission that changes by no more than about 1% over the range from 400 to 700 nm.

27. A touch input system, comprising:

a touch screen overlay comprising a substrate on which is formed a plurality of layer stacks, the plurality of layer stacks being arranged so as to leave areas of the substrate exposed by the stacks and areas of the substrate covered by the stacks, the plurality of layer stacks including a transparent conductor sensing element pattern disposed on the substrate in an active area of the touch screen, and an intermediate layer pattern coincident with the transparent conductor sensing element pattern and having a first major surface in contact with the substrate and a second major surface in contact with the transparent conductor sensing element pattern, the intermediate layer having an index of refraction that is less than that of the transparent conductor and less than that of the substrate, the touch screen overlay also including an adhesive material that covers both the areas of the substrate covered by the stacks and the areas of the substrate exposed by the stacks, the adhesive material having an index of refraction that is less than that of the transparent conductor sensing element pattern, the adhesive material also having a different material composition than the intermediate layer;

controller electronics coupled to the transparent conductor sensing element pattern and configured to receive signals from the touch screen overlay due to a touch input in the active area and to determine information related to the touch input from the received signals; and

a display device viewable through the touch screen overlay;

wherein a thickness of the transparent conductor sensing element pattern and a thickness of the intermediate layer pattern are tailored to provide a difference in visible light transmission of the touch screen overlay through the areas covered by the stacks and the areas exposed by the stacks that has a maximum over a range from 400 to 700 nm of about 1% or less and an average over the 400 to 700 nm range of about 0.5% or less.

28. The system of claim 27, wherein the touch screen overlay has a visible light transmission, in each of the areas covered by the stacks, that changes by no more than about 1% over the range from 400 to 700 nm, and wherein the touch screen overlay has a visible light transmission, in each of the areas exposed by the stacks, that changes by no more than about 1% over the range from 400 to 700 nm.