Patterned conductor touch screen having improved optics

• US 20050083307A1
• Filed: 10/15/2003
• Published: 04/21/2005
• Est. Priority Date: 10/15/2003
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Aufderheide, Brian E., Spang, Joseph C., Maag, Jonathan P.
• Granted Patent: US 8,068,186 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G02B 5/204 in which spectral selection is performed by means of a conductive grid or array, e.g. frequency selective surfaces for use with wavelengths longer than the infrared light H01Q15/0006
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

The present invention provides a touch screen that includes a pattern of transparent conductors as touch sensing elements, and that has a layered construction configured to reduce the visibility of the transparent conductor pattern. The construction includes a coating covering a substrate, the transparent conductor pattern disposed on the coating, and a filler material covering and contacting the transparent conductor pattern and the areas of the coating not covered by the transparent conductor pattern, where the index of refraction of the filler material is less than the index of refraction of the substrate and less than the index of refraction of the transparent conductor pattern.

Claims

1. A touch screen comprising:

a substrate;

a coating substantially covering the substrate;

a transparent conductor pattern disposed on the coating, the pattern leaving areas of the coating uncovered; and

a filler material covering and contacting both the transparent conductor pattern and the areas of the coating uncovered by the transparent conductor pattern;

wherein the coating has a refractive index that is less than that of the substrate and less than that of the transparent conductor pattern.

2. The touch screen of claim 1, wherein the filler material has a refractive index matching or nearly matching the refractive index of the coating.

3. The touch screen of claim 1, wherein the filler material is the same as the material of the coating.

4. The touch screen of claim 1, wherein the filler material comprises silicon oxide.

5. The touch screen of claim 1, wherein the filler material is an adhesive.

6. The touch screen of claim 1, wherein the substrate comprises plastic.

7. The touch screen of claim 1, wherein the substrate comprises polyester.

8. The touch screen of claim 1, wherein the substrate includes a hardcoat disposed on a surface opposing the coating.

9. The touch screen of claim 1, wherein the coating comprises silicon oxide.

10. The touch screen of claim 1, wherein the transparent conductor pattern comprises a transparent conductive oxide.

11. The touch screen of claim 1, wherein the transparent conductor pattern comprises indium tin oxide.

12. The touch screen of claim 1, wherein the transparent conductor pattern comprises a conductive polymer.

13. The touch screen of claim 1, wherein the substrate has a refractive index of about 1.6 to 1.7, the transparent conductor pattern has a refractive index of about 1.8 to 2.1, the coating has a refractive index of about 1.4 to 1.5, and the filler material has a refractive index of about 1.4 to 1.8.

14. The touch screen of claim 1, further comprising a second substrate disposed over the filler material.

15. The touch screen of claim 14, wherein the second substrate comprises glass.

16. The touch screen of claim 14, wherein the second substrate comprises plastic.

17. The touch screen of claim 14, wherein the second substrate comprises polyester.

18. The touch screen of claim 14, wherein the second substrate is bonded to the touch screen by an adhesive.

19. The touch screen of claim 18, wherein the adhesive is the filler material.

20. The touch screen of claim 1, wherein the coating has a thickness selected to substantially reduce reflections of visible light in areas covered by the transparent conductor pattern.

21. The touch screen of claim 1, wherein the transparent conductor pattern comprises a plurality of parallel stripes.

22. The touch screen of claim 1, wherein the transparent conductor pattern is configured for connecting to controller electronics adapted to determine touch location from signals generated when a conductive touch implement is capacitively coupled to a portion of the pattern.

23. The touch screen of claim 22 being arranged so the touch implement is capacitively coupled to the transparent conductor pattern through the substrate.

24. The touch screen of claim 22 being arranged so the touch implement is capacitively coupled to the transparent conductor pattern through the filler material.

25. The touch screen of claim 22 being arranged so the touch implement is capacitively coupled to the transparent conductor pattern through a second substrate disposed over the filler material.

26. The touch screen of claim 1 configured to be disposed over an electronic display so that the display can be viewed through the touch screen.

27. The touch screen of claim 1, further comprising a second substrate, a second coating substantially covering the second substrate, a second transparent conductor pattern disposed on the second coating to leave areas of the second coating uncovered by the pattern, and a second filler material covering and contacting both the second transparent conductor pattern and the areas of the second coating uncovered by the transparent conductor pattern.

28. A touch screen construction comprising:

a PET substrate;

an silicon oxide layer covering the PET substrate;

an array of parallel ITO bars disposed on the silicon oxide layer; and

an optically clear pressure sensitive adhesive disposed over and covering the ITO bars, the optically clear pressure sensitive adhesive having a refractive index in the range of 1.4 to 1.8 inclusive.

29. The touch screen construction of claim 28 adhered to a second substrate through the optically clear adhesive.

30. The touch screen construction of claim 29, wherein the second substrate comprises plastic.

31. The touch screen construction of claim 29, wherein the second substrate comprises glass.

32. A touch screen comprising:

a touch screen construction comprising;

a transparent conductor patterned on a substrate;

a first layer substantially covering the substrate and disposed between the transparent conductor and the substrate, the first layer configured to increase visible light transmission through the touch screen in areas covered by the transparent conductor; and

a second layer disposed to contact the transparent conductor in areas covered by the transparent conductor and to contact the first layer in areas uncovered by the transparent conductor, the second layer configured to substantially inhibit visible light reflections at contact interfaces between the first layer and the second layer.

33. The touch screen of claim 32, wherein the touch screen construction further comprises a second substrate disposed over the second layer.

34. The touch screen of claim 32, further comprising an electronic display positioned for viewing through the touch screen construction.

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

coating an undercoat material between a substrate and the patterned transparent conductor so that the undercoat material substantially covers the substrate, the undercoat material having a refractive index that is less than that of the substrate and the patterned transparent conductor, and wherein the patterned transparent conductor leaves areas of the undercoat material exposed; and

disposing a filler material over the patterned transparent conductor and exposed areas of the undercoat material, the filler material having a refractive index and thickness selected to reduce interfacial reflections of visible light in areas covered by the patterned transparent conductor.

36. The method of claim 35, further comprising the step of disposing a second substrate over the filler material.

37. The method of claim 35, further comprising the step of forming the patterned transparent conductor.