Touch Screen Having Reduced Visibility Transparent Conductor Pattern

• US 20070236618A1
• Filed: 03/31/2006
• Published: 10/11/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Maag, Jonathan, Aufderheide, Brian, Spang, Joseph
• Granted Patent: US 8,264,466 B2
• Time in Patent Office: Days
• US Class Current: 349/12
• 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 disposed between the substrate and 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; and

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,

wherein the difference in visible light transmission through the areas covered by the stacks and the areas exposed by the stacks has a maximum of about 1% or less and an average of about 0.5% or less.

2. The transparent touch screen construction of claim 1, wherein each stack further comprises an overlayer on the transparent conductor layer so that the transparent conductor layer resides between the intermediate layer and the overlayer, the overlayer having an index of refraction that is less than that of the transparent conductor layer.

3. The transparent touch screen construction of claim 1, further comprising a filler material disposed on the substrate and covering the plurality of layer stacks and the areas exposed by the plurality of layer stacks.

4. The transparent touch screen construction of claim 3, where the filler material is an optical adhesive.

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

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

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

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

9. The transparent touch screen construction of claim 3, 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 has a refractive index of about 1.8 to 2.1, and the filler material has a refractive index of about 1.4 to 1.8.

10. The transparent touch screen construction of claim 4, wherein the substrate is a first substrate, and further comprising a second substrate having an interior surface adhered to the first substrate using an optically clear adhesive and an exterior surface opposing the interior surface.

11. The transparent touch screen construction of claim 10, wherein the second substrate is plastic.

12. The transparent touch screen construction of claim 10, wherein the second substrate is PET.

13. The transparent touch screen construction of claim 10, wherein the second substrate is glass.

14. The transparent touch screen construction of claim 10, wherein the second substrate includes an anti-reflective coating on the exterior surface.

15. The transparent touch screen construction of claim 10, wherein the second substrate includes a hardcoat on the exterior surface.

16. The transparent touch screen construction of claim 10, wherein the optically clear adhesive adhering the second substrate to the first substrate is the filler material.

17. The transparent touch screen construction of claim 10, wherein the second substrate further comprises a plurality of touch sensitive elements arranged in a pattern.

18. The transparent touch screen construction of claim 17, 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.

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

patterning a transparent conductor on a substrate; and

patterning an intermediate layer between the substrate and the patterned transparent conductor, where the transparent conductor pattern and the intermediate layer pattern coincide, and where the intermediate layer has an index of refraction that is less than that of the substrate and less than that of the patterned transparent conductor.

20. The method of claim 19, further comprising the step of disposing a filler material over the patterned transparent conductor and intermediate layer, the filler material having an index of refraction that is less than that of the patterned transparent conductor.

21. The method of claim 20, further comprising the step of disposing a second substrate over the filler material.

22. The method of claim 19, wherein the steps of patterning the transparent conductor and patterning the intermediate layer occur simultaneously.

23. The method of claim 19, wherein the step of patterning the intermediate layer occurs prior to the step of patterning the transparent conductor.

24. A touch input system comprising:

a touch screen overlay comprising a substrate, 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 disposed between the substrate and 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;

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.