Acoustic touch sensor

• US 20050248547A1
• Filed: 04/13/2005
• Published: 11/10/2005
• Est. Priority Date: 04/14/2004
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: Kent, Joel C., Gomes, Paulo I.
• Granted Patent: US 7,545,365 B2
• Time in Patent Office: Days
• US Class Current: 345/177
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

A touch sensor comprises a substrate capable of propagating acoustic waves. The substrate includes a first surface having a touch sensitive region and a first sidewall intersecting the first surface at a first edge. A transmitter is provided on the first sidewall of the substrate. The transmitter generates acoustic waves that propagate directly from the first sidewall through at least a portion of the touch sensitive region.

Claims

1. A touch sensor comprising:

a substrate capable of propagating acoustic waves, the substrate including a first surface having a touch sensitive region and including a first sidewall intersecting the first surface at a first edge; and

a transmitter, provided on the first sidewall of the substrate, for generating acoustic waves that propagate directly from the first sidewall through at least a portion of the touch sensitive region.

2. The touch sensor of claim 1, wherein the first surface and the first sidewall intersect at the first edge with an angle of approximately 90°

.

3. The touch sensor of claim 1, wherein the transmitter directs the acoustic waves along a direction perpendicular to the first sidewall.

4. The touch sensor of claim 1, wherein the transmitter further comprises a first electrode having a periodic series of structures formed along the first sidewall.

5. The touch sensor of claim 1, wherein the transmitter further comprises first and second electrodes, each of the first and second electrodes including a series of fingers arranged interleaved with one another along the first sidewall.

6. The touch sensor of claim 1, wherein the sidewall comprises a first end and a second end, and the transmitter is positioned at the first end, and further comprising a waveguide directed along a length of the sidewall and a reflective array positioned along the length of the sidewall proximate the first surface.

7. The touch sensor of claim 1, wherein the transmitter includes an electrode having spaced apart fingers, the fingers oriented along the height of the sidewall, wherein the fingers are spaced apart to tune an angle of the acoustic wave directed across the touch sensitive region.

8. The touch sensor of claim 1, wherein the transmitter generates one of a shear wave, a Lamb wave and a Rayleigh wave as the acoustic wave propagating through at least a portion of the touch sensitive region.

9. The touch sensor of claim 1, wherein the acoustic wave propagating across the touch sensitive region forms an acute angle with the first sidewall.

10. The touch sensor of claim 1, further comprising a detector provided on a second sidewall of the substrate, the detector detecting the acoustic waves after traversing at least a portion of the touch sensitive region.

11. The touch sensor of claim 1, wherein the transmitter further comprises first and second transducers comprising periodic structures, the first and second transducers provided on opposed first and second sidewalls of the substrate, respectively, the first and second transducers generating first and second acoustic waves that propagate along directions oriented at acute angles to the opposed first and second sidewalls.

12. The touch sensor of claim 1, wherein the transmitter further comprises a modulation layer formed to modulate the acoustic waves in one of damping the acoustic waves, tuning and detuning the acoustic wave with respect to a resonant frequency, and shifting a phase of the acoustic wave.

13. A touch sensor system comprising:

a substrate capable of propagating acoustic waves, the substrate including a first surface having a touch sensitive region and including first and second sidewalls intersecting the first surface;

a transmitter, provided on the first sidewall of the substrate, for generating acoustic waves that propagate directly from the first sidewall, the acoustic waves propagating across at least a portion of the touch sensitive region; and

a detector, provided on the second sidewall of the substrate, for detecting the acoustic waves after traversing at least a portion of the touch sensitive region.

14. The touch sensor system of claim 13, wherein the transmitter further comprises first and second electrodes, each of the first and second electrodes further comprising periodic structures along the first sidewall.

15. The touch sensor system of claim 13, wherein the transmitter further comprises first and second interdigital transducers provided on opposed first and third sidewalls of the substrate, respectively, the first and second interdigital transducers generating first and second acoustic waves that propagate along directions oriented at acute angles to the opposed first and third sidewalls.

16. The touch sensor system of claim 13, wherein the sidewall comprises a first end and a second end, and the transmitter is positioned at the first end, and further comprising a waveguide directed along a length of the sidewall and a reflective array positioned along the length of the sidewall proximate the first surface, the waveguide being one of a strip bonded to the sidewall and a groove formed by removing material from the sidewall.

17. A method for detecting a touch on a touch sensitive region of a substrate capable of propagating acoustic waves, the substrate including a first surface having the touch sensitive region, the substrate having first and second sidewalls intersecting the first surface, the method comprising:

generating an acoustic wave proximate the first sidewall of the substrate;

directing the acoustic wave through a portion of the first sidewall of the substrate into the substrate and across at least a portion of the touch sensitive region; and

detecting the acoustic wave proximate the second sidewall of the substrate.

18. The method of claim 17, wherein the detecting further comprises detecting perturbations in the acoustic wave, the perturbations being indicative of a location of a touch event.

19. The method of claim 17, wherein the directing further comprises directing the acoustic wave along a linear direction extending directly from a source located along a length of the first sidewall through at least a portion of the touch sensitive region, wherein the acoustic wave completes a signal path without being reflected.

20. The method of claim 17, wherein the directing further comprising directing the acoustic wave along a length of the first sidewall and reflecting the acoustic wave in a