Acoustic touch sensor utilizing edge waves
View Patent ↗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.
1. A touch sensor, comprising:
a substrate capable of propagating acoustic surface waves, the substrate including a first surface having a touch sensitive region and including a non-coplanar second surface intersecting the first surface along a first edge, the first edge being configured to propagate a first acoustic surface wave along the first edge, the first surface being configured to propagate a second acoustic surface wave across the touch sensitive region, the second acoustic surface wave being based on the first acoustic surface wave; and
a wave converter for converting between the first and second acoustic surface waves, the wave converter comprising partially reflecting elements being formed on the substrate.
2. The touch sensor of claim 1 , wherein the first edge has a curved region, the touch sensor further comprising a transducer configured for producing and receiving the first acoustic surface waves, the transducer mounted on the substrate.
3. The touch sensor of claim 2 , further comprising at least two transducers mounted to the substrate, the at least two transducers being used to produce or receive acoustic surface waves.
4. The touch sensor of claim 1 , the first surface being at least partially curved.
5. The touch sensor of claim 4 , further comprising at least two transducers mounted to the substrate, the at least two transducers being used to produce or receive acoustic surface waves.
6. The touch sensor of claim 4 , the partially reflective elements being protrusions or grooves regularly spaced with respect to each other by a wavelength of the first acoustic surface wave.
7. The touch sensor of claim 4 , wherein the substrate has a second edge opposite the first edge, the second edge reflecting the second acoustic surface wave after traversing at least a portion of the touch sensitive region.
8. The touch sensor of claim 4 , further comprising a transducer mounted on the substrate to transmit a fourth wave, the substrate including a third surface intersecting the first surface along a third edge, the third edge being configured to propagate a third acoustic surface wave, the second and third surfaces intersecting proximate the transducer, wherein the first and third acoustic surface waves are split from the fourth acoustic surface wave, and wherein the first, third and fourth acoustic surface waves comprise acoustic edge waves.
9. The touch sensor of claim 1 , further comprising transducers mounted to the substrate for producing and receiving the first acoustic surface waves, each of the transducers producing and receiving the first acoustic surface waves to detect coordinates over an area of the touch sensitive region wherein the area may be one of an entire touch sensitive region and a portion of the touch sensitive region.
10. The touch sensor of claim 9 , further comprising:
the substrate further comprising four sidewalls intersecting the first surface along four edges, the sidewalls forming corners with adjacent sidewalls, one of the sidewalls comprising the second surface;
a transducer mounted at each corner, the transducer for producing or receiving an acoustic surface wave; and
the wave converter mounted at or proximate to each of the four edges.
11. The touch sensor of claim 9 , further comprising:
a second sidewall intersecting the first surface along a second edge, the second edge being formed substantially free of defects; and
one or more reflective strips formed proximate the second edge, the reflective strips being spaced apart from each other by an integer times a one-half wavelength of the second acoustic surface wave, the reflective strips and the second edge reflecting the second acoustic surface wave after traversing at least a portion of the touch sensitive region.
12. The touch sensor of claim 1 , further comprising at least two transducers mounted to the substrate, the at least two transducers being used to produce or receive acoustic surface waves.
13. The touch sensor of claim 1 , the touch sensitive region receiving touch events having two coordinates, the two coordinates identifying a location of the touch event with respect to the touch sensitive region, further comprising first and second transducers mounted to the substrate, the first transducer being used to produce and receive the first acoustic surface waves to detect a first coordinate of the touch event on the touch sensitive region, the second transducer being used to produce and receive the first acoustic surface waves to detect a second coordinate of the touch event on the touch sensitive region.
14. The touch sensor of claim 1 , the touch sensitive region receiving touch events having two coordinates, the two coordinates identifying a location of the touch event with respect to the touch sensitive region, further comprising at least two transducers mounted to the substrate, wherein at least one of the at least two transducers is used to produce and receive the first acoustic surface waves to detect a coordinate of the touch event.
15. The touch sensor of claim 1 , further comprising a second sidewall intersecting the first surface along a second edge, the second edge being formed substantially free of defects, the second edge forming an approximate 90° angle between the second sidewall and the first surface, the second edge reflecting the second acoustic surface wave after traversing at least a portion of the touch sensitive region.
16. The touch sensor of claim 1 , the partially reflective elements being protrusions or grooves regularly spaced with respect to each other by a wavelength of the first acoustic surface wave.
17. The touch sensor of claim 16 , wherein the partially reflective elements extend along the first edge, the partially reflective elements having a length from the first edge of less than the wavelength of the first acoustic surface wave.
18. The touch sensor of claim 1 , wherein the substrate has a second edge opposite the first edge, the second edge reflecting the second acoustic surface wave after traversing at least a portion of the touch sensitive region.
19. The touch sensor of claim 1 , the first surface being hemispherical.
20. The touch sensor of claim 1 , further comprising a transducer mounted on the substrate to transmit a fourth wave, the substrate including a third surface intersecting the first surface along a third edge, the third edge being configured to propagate a third acoustic surface wave, the second and third surfaces intersecting proximate the transducer, wherein the first and third acoustic surface waves are split from the fourth acoustic surface wave, and wherein the first, third and fourth acoustic surface waves comprise acoustic edge waves.