Resistive touch sensor having microstructured conductive layer

• US 7,019,734 B2
• Filed: 07/17/2002
• Issued: 03/28/2006
• Est. Priority Date: 07/17/2002
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Whitney, Leland R., Cross, Elisa M., Moshrefzadeh, Robert S.
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US10/196,794
• Publication Number:
  US 20040012570A1
• Time in Patent Office: 1,350 Days
• Field of Search: 345173-180, 178 1801- 1809, 178 1901- 1907
• US Class Current: 345/173
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

The present invention discloses resistive touch sensors that incorporate microstructured conductive layers. When local electrical contact is made between the microstructured conductive layer and an opposing conductive layer due to a touch input, the resulting signal can be used to determine the location of the touch. The microstructures can be used to penetrate a solid, deformable filler material disposed between the conductive layers, for example to provide more transmission of light through the sensor. The microstructures can also provide additional functionalities such as z-axis sensitivity, image direction, light control, light extraction, and so forth.

Claims

1. A touch sensor for determining the location of a touch input comprising:

a first plurality of conductive microstructures disposed on a flexible substrate; and

a second plurality of conductive microstructures spaced apart from and facing the first plurality of conductive microstructures,

wherein the location of the touch input is determined using an electrical signal produced by local electrical contact between a portion of the first plurality of conductive microstructures and a portion of the second plurality of conductive microstructures, the local electrical contact due to the touch input.

2. The touch sensor of claim 1, further comprising a filler material disposed between the first and second plurality of conductive microstructures.

3. The touch sensor of claim 2, wherein the filler material is solid and deformable.

4. A touch sensor for determining a location of a touch input comprising:

a conductive layer;

a plurality of conductive microstructures facing the conductive layer; and

a solid, deformable filler material disposed between the conductive layer and the conductive microstructures,

wherein the location of the touch input is determined using an electrical signal produced by local electrical contact between the conductive layer and a portion of the conductive microstructures due to the touch input.

5. The touch sensor of claim 4, wherein the filler material comprises a visible light transmissive material.

6. The touch sensor of claim 4, wherein the filler material comprises an elastomer.

7. The touch sensor of claim 4, wherein the filler material comprises a silicone.

8. The touch sensor of claim 4, wherein the filler material comprises a clear silicone.

9. The touch sensor of claim 4, wherein the conductive microstructures are disposed on a flexible substrate.

10. The touch sensor of claim 4, wherein the conductive layer is disposed on a flexible substrate.

11. The touch sensor of claim 4, wherein the conductive microstructures act as an electrical sink when local electrical contact is made between the conductive layer and at least a portion of the conductive microstructures.

12. The touch sensor of claim 4, wherein the conductive layer comprises a transparent conductive oxide.

13. The touch sensor of claim 4, wherein the conductive layer comprises a conductive polymer.

14. The touch sensor of claim 4, wherein the conductive microstructures comprise a transparent conductive oxide.

15. The touch sensor of claim 4, wherein the conductive microstructures comprises a conductive polymer.

16. The touch sensor of claim 4, wherein the conductive microstructures comprise a conformal conductive coating disposed over a plurality of protrusions.

17. The touch sensor of claim 4, wherein the conductive microstructures comprise ridges.

18. The touch sensor of claim 4, wherein the conductive microstructures comprise posts.

19. The touch sensor of claim 4, wherein the filler material further comprises particles dispersed therein.

20. The touch sensor of claim 19, wherein the particles comprise conductive particles.

21. The touch sensor of claim 4, wherein the conductive microstructures comprise a patterned conductive layer.

22. The touch sensor of claim 21, wherein the microstructures comprise parallel ridges, and the patterned conductive layer comprises stripes of conductive material residing on the parallel ridges.

23. The touch sensor of claim 4, wherein the conductive layer is patterned.

24. The touch sensor of claim 4, wherein the microstructures comprise a first plurality of protrusions that rise to substantially the same first height and a second plurality of protrusions that rise to substantially the same second height different from the first height.

25. A touch sensor comprising:

a first substrate comprising a first conductive layer;

a second substrate comprising a second conductive layer conformally covering a plurality of microstructures; and

a solid, deformable filler material disposed between the first and second conductive layers,

wherein at least one of the first and second substrates is flexible to allow electrical contact between the first conductive layer and the second conductive layer upon application of a force from a touch input so that the touch input location can be determined.

26. The touch sensor of claim 25, wherein the deformable material comprises an elastomeric material.

27. The touch sensor of claim 25, wherein the deformable material is disposed so that substantially no air gaps exist between the first and second conductive layers.

28. The touch sensor of claim 25, wherein the plurality of microstructures comprise bumps.

29. The touch sensor of claim 25, wherein the plurality of microstructures comprise posts.

30. The touch sensor of claim 25, wherein the plurality of microstructures comprise ribs.

31. The touch sensor of claim 25, wherein the first substrate is flexible.

32. The touch sensor of claim 25, wherein the second substrate is flexible.

33. The touch sensor of claim 25, wherein the first conductive layer comprises a transparent conductive oxide.

34. The touch sensor of claim 25, wherein the first conductive layer comprises a conductive polymer.

35. The touch sensor of claim 25, wherein the second conductive layer comprises a transparent conductive oxide.

36. The touch sensor of claim 25, wherein the second conductive layer comprises a conductive polymer.

37. The touch sensor of claim 25, wherein the first conductive layer is patterned.

38. The touch sensor of claim 25, wherein the second conductive layer is patterned.

39. The touch sensor of claim 25, wherein the microstructures comprise a first plurality of protrusions that rise to substantially the same first height and a second plurality of protrusions that rise to substantially the same second height different from the first height.

40. A method of determining the location of a touch on a touch screen comprising:

contacting a first electrode layer and a second electrode layer in response to the touch, the first electrode layer comprising a plurality of microstructures, a portion of the microstructures penetrating through a solid, deformable filler material during the contacting step; and

measuring a signal due to contacting the first electrode layer and second electrode layer.