Acoustic touch apparatus with variable thickness substrate
View Patent ↗An acoustic touch apparatus that has a variable thickness glass substrate that permits the transfer of surface acoustic waves between the back and front surfaces, thus enabling transducers to be placed on the substrate surface opposite the desired touch input surface.
1. An acoustic touch apparatus, comprising a substrate, having top and bottom surfaces, that is adapted in a first region to propagating surface acoustic waves along substrate surfaces and in a second region to transferring propagating surface acoustic waves from the one of the surfaces to the other surface through the substrate via top-bottom oscillation; at least one acoustic wave transducer on the bottom surface that is adapted to transmit surface acoustic waves; and at least one acoustic wave transducer on the bottom surface that is adapted to receive surface acoustic waves from the transmitting transducer, said substrate having, between the transmitting transducer and the receiving transducer, at least one first region disposed between two second regions.
2. The apparatus of claim 1 , wherein the first region has a thickness that is at least 3.5 Rayleigh wavelengths.
3. The apparatus of claim 1 , wherein the first region has a thickness that is at least 5.5 Rayleigh wavelengths.
4. The apparatus of claim 1 , wherein the second region has a thickness sufficiently thin to convert a surface acoustic wave on a first surface to a surface acoustic wave on a second surface.
5. The apparatus of claim 4 , wherein the second region is dimensioned to inhibit the surface acoustic wave on the second surface from converting back to a surface acoustic wave on the first surface.
6. The apparatus of claim 1 , wherein the second region has a thickness sufficiently thin to transfer acoustic surface wave energy between the top and bottom surfaces of the substrate.
7. The apparatus of claim 1 , wherein the first region and the second regions are dimensioned so that the surface acoustic waves transmitted by the transmitting transducer travel from the bottom surface to the top surface through the substrate; along the top surface; and from the top surface to the bottom surface through the substrate to be received by the receiving transducer, said top surface forming a touch sensing region for the apparatus.
8. The apparatus of claim 7 , wherein the length of the second region is approximately one-half of the beat wavelength of the surface acoustic waves.
9. The apparatus of claim 8 , wherein thickness of the second region is adjustable to tune the beat wavelength and the length of the second region to selected respective measurements.
10. The apparatus of claim 7 , wherein the length of the first region is shorter than the beat wavelength of the surface acoustic waves.
11. The apparatus of claim 1 , wherein a portion of the bottom surface in the second region has a coating material applied thereon sufficient to suppress the transfer of acoustic surface wave energy between the top and bottom surfaces of the substrate within that portion.
12. An acoustic touch apparatus, comprising:
a. a substrate that has top and bottom surfaces and that is adapted in a first region to propagating surface acoustic waves along substrate surfaces and in a second region to transferring propagating surface acoustic waves from the one of the surfaces to the other surface through the substrate via top-bottom oscillation;
b. at least one acoustic wave transducer on the bottom surface that is adapted to transmit surface acoustic waves;
c. at least one acoustic wave transducer on the bottom surface that is adapted to receive surface acoustic waves;
d. at least one reflective array on the bottom surface that is adapted to reflect the surface acoustic waves from the transmitting transducer towards the receiving transducer; and
e. at least one reflective array on the bottom surface that is adapted to receive and reflect the reflected transmitted surface acoustic waves to the receiving transducer, said substrate having, between the transmitting transducer and the receiving transducer, at least one first region disposed between two second regions.
13. The apparatus of claim 12 , wherein the first region has a thickness that is at least 3.5 Rayleigh wavelengths.
14. The apparatus of claim 12 , wherein the first region has a thickness that is at least 5.5 Rayleigh wavelengths.
15. The apparatus of claim 12 , wherein the second region has a thickness sufficiently thin to convert a surface acoustic wave on a first surface to a surface acoustic wave on a second surface.
16. The apparatus of claim 15 , wherein the second region is dimensioned to inhibit the surface acoustic wave on the second surface from converting back to a surface acoustic wave on the first surface.
17. The apparatus of claim 12 , wherein the second region has a thickness sufficiently thin to transfer acoustic surface wave energy between the top and bottom surfaces of the substrate.
18. The apparatus of claim 12 , wherein the first region and the second regions are dimensioned so that the surface acoustic waves transmitted by the transmitting transducer and reflected by the first reflective array travel from the bottom surface to the top surface through the substrate; along the top surface; and from the top surface to the bottom surface through the substrate to be reflected by the second reflective array to the receiving transducer, said top surface forming a touch sensing region for the apparatus.
19. The apparatus of claim 18 , wherein the length of the second region is approximately one-half of the beat wavelength of the surface acoustic waves.
20. The apparatus of claim 19 , wherein thickness of the second region is adjustable to tune the beat wavelength and the length of the second region to selected respective measurements.
21. The apparatus of claim 18 , wherein the length of the first region is shorter than the beat wavelength of the surface acoustic waves.
22. The apparatus of claim 12 , wherein a portion of the bottom surface in the second region has a coating material applied thereon sufficient to suppress the transfer of acoustic surface wave energy between the top and bottom surfaces of the substrate within that portion.