Capacitive touch screen with conductive polymer

• US 7,477,242 B2
• Filed: 05/20/2002
• Issued: 01/13/2009
• Est. Priority Date: 05/20/2002
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Moshrefzadeh, Robert S., Bottari, Frank J., Cairns, Darran R., Richter, Paul J., Cross, Elisa M., Chernefsky, Anthony F.
• Primary Examiner(s): Nguyen; Kevin M
• Application Number:
  US10/152,260
• Publication Number:
  US 20030213624A1
• Time in Patent Office: 2,430 Days
• Field of Search: 345173-183, 178/18.06
• US Class Current: 345/179
• CPC Class Codes: G06F 3/0444 using a single conductive element covering the whole sensing surface, e.g. by sensing the electrical current flowing at the corners

Abstract

A capacitive touch screen is described with a touch area including a substantially transparent conductive polymer. The capacitive touch screen also includes circuitry connecting the conductive polymer of the touch area to a power source, where the circuitry is configured to determine a location of a capacitive coupling on the touch area.

Claims

1. A capacitive touch screen comprising:

a touch area comprising a substantially transparent conductive polymer acting as a primary signal carrier for making a capacitive coupling to an object at a touch location; and

circuitry connecting the conductive polymer of the touch area to a power source, the circuitry configured to determine the touch location.

2. The capacitive touch screen of claim 1 wherein the touch area does not include a transparent conductive oxide.

3. The capacitive touch screen of claim 1 wherein the conductive polymer is the only transparent conductive element in the touch area.

4. The capacitive touch screen of claim 1 further comprising a protective coating on the conductive polymer.

5. The capacitive touch screen of claim 4 wherein the protective coating serves as a dielectric layer.

6. The capacitive touch screen of claim 1 wherein the conductive polymer is PEDOT.

7. The capacitive touch screen of claim 1 further comprising:

a substrate wherein the touch area is formed on the substrate; and

a display device positioned adjacent to the substrate.

8. The capacitive touch screen of claim 1 further comprising a rigid substrate, wherein the touch area is formed on the substrate.

9. The capacitive touch screen of claim 1 further comprising a flexible substrate, wherein the touch area is formed on the substrate.

10. The capacitive touch screen of claim 1 wherein the touch area comprises a sheet of conductive polymer having a substantially uniform resistance.

11. The capacitive touch screen of claim 1 wherein the touch area comprises a pattern of conductive polymer.

12. The capacitive touch screen of claim 11 wherein the pattern of conductive polymer comprises a plurality of parallel sensor bars.

13. The capacitive touch screen of claim 1 wherein the touch panel is configured to create a substantially uniform current density in the touch area.

14. The capacitive touch screen of claim 1 further comprising a linearization pattern.

15. A touch panel for locating a touch point, comprising:

a current-conducting impedance surface having at least a pair of boundaries, the impedance surface comprising a conductive polymer;

wherein the touch panel is configured to cause a substantially linearized electrical current through the impedance surface, wherein currents passing through a touch point on the impedance surface from each of the boundaries determine a location of the touch point.

16. The touch panel of claim 15 wherein the impedance surface does not include a transparent conductive oxide.

17. The touch panel of claim 15 wherein the conductive polymer is the only transparent conductive element on the impedance surface.

18. The touch panel of claim 15 further comprising a protective coating on the impedance surface.

19. The touch panel of claim 18 wherein the protective coating serves as a dielectric layer.

20. The touch panel of claim 15 wherein the conductive polymer is PEDOT.

21. The touch panel of claim 15 wherein the impedance surface is formed on a flexible substrate.

22. The touch panel of claim 15 wherein the impedance surface is formed on a rigid substrate.

23. The touch panel of claim 15 wherein the impedance surface comprises a sheet of conductive polymer having a substantially uniform resistance.

24. The touch panel of claim 15 wherein the impedance surface comprises a pattern of conductive polymer.

25. The touch panel of claim 15 wherein the pattern of conductive polymer comprises a plurality of parallel sensor bars.

26. The touch panel of claim 15 further comprising a linearization pattern.

27. A touch sensitive display module comprising:

a touch area comprising a substantially transparent conductive polymer acting as a primary signal carrier for making a capacitive coupling to an object at a touch location;

circuitry connecting the conductive polymer of the touch area to a power source, the circuitry configured to determine the touch location; and

a display device having a display surface.

28. The touch sensitive display device of claim 27 wherein the touch area does not include a transparent conductive oxide.

29. The touch sensitive display device of claim 27 wherein the conductive polymer is the only transparent conductive element in the touch area.

30. The touch sensitive display device of claim 27 further comprising a protective coating on the conductive polymer.

31. The touch sensitive display device of claim 30 wherein the protective coating serves as a dielectric layer.

32. The touch sensitive display device of claim 27 wherein the conductive polymer is an intrinsically conductive polymer.

33. The touch sensitive display device of claim 27 wherein the conductive polymer is PEDOT.

34. The touch sensitive display device of claim 27 further comprising a rigid substrate, wherein the touch area is formed on the substrate.

35. The touch sensitive display device of claim 27 further comprising a flexible substrate, wherein the touch area is formed on the substrate.

36. The touch sensitive display device of claim 27 wherein the touch area comprises a sheet of conductive polymer having a substantially uniform resistance.

37. The touch sensitive display device of claim 27 wherein the touch area comprises a pattern of conductive polymer.

38. The touch sensitive display device of claim 37 wherein the pattern of conductive polymer comprises a plurality of parallel sensor bars.

39. The touch sensitive display device of claim 27 wherein the touch panel is configured to create a substantially uniform current density the touch area.

40. The touch sensitive display device of claim 27 further comprising a linearization pattern.

41. A method of making a capacitive touch screen comprising:

providing a substrate;

forming a touch area on the substrate comprising a substantially transparent conductive polymer, wherein the conductive polymer is configured to act as a primary signal carrier for making a capacitive coupling to an object.

42. The method of making a capacitive touch screen of claim 41 further comprising forming a protective layer on the touch area.

43. The method of making a capacitive touch screen of claim 41 wherein the object is selected from the group consisting of a user'"'"'s body part, a conductive stylus, or a conductive stylus connected to an earth ground.

44. The method of making a capacitive touch screen of claim 41 further comprising forming a linearization pattern on the touch area.