Acoustic touch sensor with laminated substrate

• US 20020104691A1
• Filed: 10/05/2001
• Published: 08/08/2002
• Est. Priority Date: 10/20/2000
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: Adler, Robert, Adriani, Paul M., Kent, Joel
• Granted Patent: US 7,006,081 B2
• Time in Patent Office: Days
• US Class Current: 178/18.04
• CPC Class Codes: G06F 3/043 using propagating acoustic waves

Abstract

The present invention is directed to a multilayer substrate for use in touchscreen and touch sensor applications. The substrate, including a microsheet, a polymer sheet, and a plate supports the propagation of acoustic waves, including Love waves and Rayleigh-like waves. The microsheet and plate may be fabricated from glass, metal, or other suitable materials depending on the desired application for the touchscreen. The polymer sheet may be fabricated from polystyrene, polyacrylates, polyether sulfones, or polycyclic olefins. The disclosed touchscreen substrates are thin but durable and have increased touch sensitivity with decreased sensitivity to water and other surface contaminants.

Claims

1. An acoustic touch sensor substrate comprising:

a first shear supporting sheet comprising an upper surface and a lower surface, said upper surface comprising a touch surface;

a shear supporting plate; and

a second flexible sheet comprising a shear supporting polymer positioned between said first sheet and said plate.

2. The acoustic touch sensor substrate of claim 1, wherein said substrate supports Love waves and Rayleigh-like waves.

3. The acoustic touch sensor substrate of claim 1, wherein said thickness of said first sheet is less than about 300 microns.

4. The acoustic touch sensor substrate of claim 1, wherein said thickness of the first sheet is about 50 to 200 microns.

5. The acoustic touch sensor substrate of claim 1, wherein said thickness of said second flexible sheet is about 10 to 100 microns.

6. The acoustic touch sensor substrate of claim 1, wherein said substrate has a total thickness less than 2 millimeters.

7. The acoustic touch sensor substrate of claim 1, wherein said shear supporting polymer has a glass transition temperature above about 260°

K.

8. The acoustic touch sensor substrate of claim 7, wherein said shear supporting polymer is selected from the group consisting of polystyrene, polyacrylate, polycyclic olefins, polyether sulfones, and mixtures thereof.

9. The acoustic touch sensor substrate of claim 1, wherein said first sheet, said second flexible sheet, and said plate are substantially transparent.

10. The acoustic touch sensor substrate of claim 1, wherein said first sheet and said plate comprise glass.

11. The acoustic touch sensor substrate of claim 1, wherein said plate further comprises an upper surface adjacent the polymer sheet and a lower surface opposite said upper surface wherein a second plate is adhered to the lower surface of said plate.

12. The acoustic touch sensor substrate of claim 1, wherein said first sheet and said plate comprise metal.

13. The acoustic touch sensor substrate of claim 1, wherein said first sheet and the plate have bulk shear wave velocities, and the bulk shear wave velocity of the sheet is slower than the bulk sheer wave velocity of the plate.

14. The acoustic touch sensor substrate of claim 13, wherein the bulk shear wave velocity of said first sheet is more than about 5% slower than the bulk shear wave velocity in said plate.

15. The acoustic touch sensor substrate of claim 1, wherein said first sheet and said plate are laminated to said second flexible sheet with a coupling agent.

16. The acoustic touch sensor substrate of claim 15, wherein the coupling agent comprises silane.

17. The acoustic touch sensor substrate of claim 1, wherein said second flexible sheet comprises spacer particles.

18. The acoustic touch sensor substrate of claim 1, wherein said first sheet comprises glass having a thickness of about 100 microns, said second flexible sheet comprises polystyrene having a thickness of about 32 microns, and said plate comprises glass having a thickness greater than about 0.5 mm.

19. The acoustic touch sensor substrate of claim 1, wherein said substrate supports Love waves operating at a frequency having a dispersion parameter less than about one.

20. The acoustic touch sensor substrate of claim 19, wherein said operating frequency is between about 1 to 10 MHz.

21. The acoustic touch sensor substrate of claim 1, wherein said substrate supports Rayleigh-like waves operating at a frequency having a dispersion parameter less than about one.

22. The acoustic touch sensor substrate of claim 21, wherein said operating frequency is about 1 to 10 MHz.

23. The acoustic touch sensor substrate of claim 1, wherein said substrate supports Rayleigh-like waves and Love waves operating at a frequency having a dispersion parameter less than about one.

24. The acoustic touch sensor of claim 23, wherein said operating frequency is about 1 to 10 MHz.

25. The acoustic touch sensor substrate of claim 1 further comprising a third sheet shear supporting sheet, and a fourth sheet comprising a polymer.

30. The acoustic touch system of claim 28 wherein, the electronic circuitry corrects the dispersion effects with digital signal processing.

31. The acoustic touch sensor substrate of claim 21, wherein only one surface-bound Rayleigh-like exists at the desired operating frequency.

32. The acoustic touch sensor substrate of claim 21 wherein the operating frequency is within about 30% of a cut-off frequency of a second Rayleigh-like wave.

26. An acoustic touch sensor substrate comprising:

a first flexible sheet having a touch surface;

a back plate; and

a flexible sheet comprising an acoustic-wave-supporting polymer positioned between said first sheet and said plate.

27. An acoustic touch sensor substrate comprising:

a shear supporting flexible microsheet having a touch surface;

a shear supporting back plate; and

a flexible sheet comprising a shear supporting polymer positioned between said first sheet and said plate.

28. An acoustic touch sensor substrate comprising:

a first shear supporting sheet having a thickness less than about 300 microns;

a shear supporting plate having a thickness less than bout 12 mm; and

a second sheet comprising a shear supporting polymer disposed between said first sheet and said plate, said second sheet having a thickness less than about 100 microns.

29. An acoustic touch system comprising:

a touch substrate comprising;

a first sheet having a shear supporting touch surface;

a shear supporting plate; and

a second flexible sheet comprising a shear supporting polymer positioned between said first sheet and said plate; and

electronic circuitry which corrects for dispersion effects.

33. An acoustic touch sensor substrate for use in a touch system comprising:

a microsheet having an upper surface and a lower surface;

a plate having an upper surface and a lower surface;

a shear wave supporting polymer sheet positioned between the lower surface of the microsheet and the upper surface of the plate;

at least one component of a transducer disposed on said microsheet; and

at least one reflective array disposed on said microsheet.

35. The method of claim 34 wherein the first acoustic wave and the second acoustic wave are Love waves.

36. The method of claim 34 wherein said first acoustic wave and said second acoustic wave are Rayleigh-like waves.

37. The method of claim 34 wherein the first acoustic wave is a Rayleigh-like wave and the second acoustic wave is Love wave.

34. A method of detecting an object comprising:

providing a substrate with at least one touch surface, said substrate comprising;

a flexible microsheet;

a plate; and

a shear supporting polymer sheet positioned between the microsheet and plate;

wherein said substrate supports Rayleigh-like waves and Love waves;

inducing a first surface bound acoustic wave having a direction of propagation along a first axis in the substrate;

reflecting as a second surface bound acoustic wave, portions of the first surface bound wave, said second surface bound wave being directed along a second axis in the substrate, different from the first axis and parallel to said surface;

perturbing said second acoustic wave by placing an object in proximity to said surface; and

detecting the perturbed second acoustic signal.