Acoustic touch sensor

• US 20050243071A1
• Filed: 04/13/2005
• Published: 11/03/2005
• Est. Priority Date: 04/14/2004
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touch Solutions, Inc.
• Inventors: Adler, Robert, Kent, Joel C., Gomes, Paulo I.
• Granted Patent: US 8,325,159 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 and includes a first surface having a touch sensitive region. A first sidewall intersects the first surface along a first edge. The first edge is configured to propagate a first acoustic wave along the first edge. The first acoustic wave may be a one-dimensional edge wave. A wave converter converts the first acoustic wave to a second acoustic wave, and the first surface is configured to propagate the second acoustic wave across 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 along a first edge, the first edge being configured to propagate a first acoustic wave along the first edge, the first surface being configured to propagate a second acoustic wave across the touch sensitive region, the second acoustic wave being based on the first acoustic wave; and

a wave converter for converting the first acoustic wave to the second acoustic wave.

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

.

3. The touch sensor of claim 1, further comprising a transducer provided proximate the first edge, the transducer producing the first acoustic wave propagating along the first edge, the transducer receiving the second acoustic wave propagating across the touch sensitive region.

4. The touch sensor of claim 1, wherein the wave converter comprises a partially reflective element located immediately adjacent the first edge.

5. The touch sensor of claim 1, wherein the second acoustic wave is one of a Shear wave, a Lamb wave, and a Rayleigh wave.

6. The touch sensor of claim 1, wherein the wave converter comprises a first array of partially reflective elements positioned proximate the first edge for converting the first acoustic wave propagating along the first edge to the second acoustic wave propagating on the substrate.

7. The touch sensor of claim 1, wherein the wave converter comprises partially reflective elements that are spaced apart by approximately a wavelength of the first acoustic wave.

8. The touch sensor of claim 1, wherein the wave converter including reflective elements having regularly spaced grooves.

9. The touch sensor of claim 1, further comprising a transducer provided proximate the first edge, the transducer producing the first acoustic wave propagating along the first edge.

10. The touch sensor of claim 1, further comprising a diffractive grating comprising a series of regularly spaced grooves proximate the first edge, the grooves extending from the first edge along the first surface for a distance of less than a wavelength of the first acoustic wave.

11. The touch sensor of claim 1, further comprising a transducer proximate the first edge, the transducer including a shear-mode piezo provided on a surface of the substrate perpendicular to a direction of propagation of the first acoustic wave.

12. A touch sensor system comprising:

a transmitter for generating a one-dimensional first acoustic wave;

a touch sensor 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 along first and second edges, the first edge being configured to propagate the first acoustic wave, the first surface being configured to propagate a second acoustic wave across the touch sensitive region;

a first converter, provided on the substrate, for converting the first acoustic wave to the second acoustic wave propagating on the substrate across the touch sensitive region; and

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

13. The touch sensor system of claim 12, wherein at least one of the transmitter and detector comprises a piezoelectric element.

14. The touch sensor system of claim 12, wherein the first converter comprises an array of reflective elements positioned proximate the first edge.

15. The touch sensor system of claim 12, further comprising a controller driving the transmitter to generate the first acoustic wave and receiving signals from the detector.

16. The touch sensor system of claim 12, further comprising a second wave converter for converting the second acoustic wave to a one-dimensional third acoustic wave detected by the detector.

17. The touch sensor system of claim 12, wherein the substrate is transparent such that the touch sensor can function as a touchscreen.

18. 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 along first and second edges, the method comprising:

transmitting a one-dimensional first acoustic wave along the first edge;

converting the first acoustic wave into a second acoustic wave;

directing the second acoustic wave along the first surface through the touch sensitive region; and

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

19. The method of claim 18, wherein the detecting step includes detecting perturbations in the second acoustic wave, the perturbations being indicative of a location of a touch event.

20. The method of claim 18, wherein the detecting step further comprises converting the second acoustic wave into a one-dimensional third acoustic wave and detecting the third acoustic wave proximate one of the first and second edges.