ACOUSTIC TOUCH APPARATUS WITH MULTI-TOUCH CAPABILITY

• US 20130234995A1
• Filed: 03/09/2012
• Published: 09/12/2013
• Est. Priority Date: 03/09/2012
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touch Solutions, Inc.
• Inventors: Son, Kyu-Tak, Kent, Joel C.
• Granted Patent: US 9,201,546 B2
• Time in Patent Office: Days
• US Class Current: 345/177
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: G06F 3/0433 in which the acoustic waves are either generated by a movable member and propagated within a surface layer or propagated within a surface layer and captured by a movable member

Abstract

An acoustic touch apparatus that utilizes the transfer of surface acoustic waves from one surface, through the touch substrate, to another surface to enable multi-touch capabilities.

Claims

1. An acoustic touch apparatus that distinguishes simultaneous touches, comprising a substrate that is adapted to utilize a transfer of surface acoustic waves, through the substrate, between opposite surfaces of the substrate to vary touch sensitivity along a respective acoustic path across a substrate touch region and acoustic transducers that are adapted to transmit and receive surface acoustic waves travelling on the opposite substrate surfaces, said substrate touch region providing additional signal information of touch responses of receiving transducers sufficient to permit the apparatus to determine an axis coordinate of a respective touch on the substrate touch region.

2. The apparatus of claim 1, wherein the additional signal information comprises a comparison of the touch responses of receiving transducers with non-touch responses of the receiving transducers.

3. The apparatus of claim 1, wherein the additional signal information comprises a comparison of the signal level changes of the touch responses of receiving transducers.

4. An acoustic touch apparatus, comprising:

a substrate that has top and bottom surfaces;

a transmitting and receiving acoustic wave transducer pair on the top surface that is adapted to transmit and receive surface acoustic waves therebetween across a touch region on the top surface and to produce a touch response signal for a touch on the touch region;

a transmitting and receiving acoustic wave transducer pair on the bottom surface that is adapted to transmit and receive surface acoustic waves therebetween, said substrate being adapted to propagate surface acoustic waves along each surface and to transfer, through the substrate, surface acoustic waves between the surfaces sufficient to enable a touch on the top surface to produce a touch response signal by the bottom surface transducer pair; and

a controller that operates on the touch response signals and non-touch response signals produced by each of the bottom surface transducer pair and the top surface transducer pair and determines positional information of a touch on the touch region from the response signals.

5. The apparatus of claim 4, wherein the controller operates on the response signals to determine the top and bottom touch sensitivity along an acoustic path across the touch region.

6. The apparatus of claim 5, wherein the top and bottom sensitivity is represented by the reduction in amplitude of the touch response signal to the non-touch response signal for each of the bottom surface transducer pair and the top surface transducer pair.

7. The apparatus of claim 6, wherein the controller determines positional information of a touch by comparing the amplitude reductions of the touch response of the bottom surface transducer pair to the touch response of the top surface transducer pair.

8. The apparatus of claim 6, wherein the controller determines positional information of a touch by applying the following relation:

b(d)/t(d)={b(L/2)/t(L/2)}·

d·

(L−

d)/(L/2)², where L is the distance between the transducers in a respective transducer pair on the top and bottom surfaces;

b(d) is the amplitude reduction of the touch response for a touch at distance d by the bottom surface transducer pair; and

t(d) is the amplitude reduction of the touch response for a touch at distance d by the top surface transducer pair.

9. The apparatus of claim 5, wherein the substrate is adapted to propagate surface acoustic waves along each surface and to transfer, through the substrate, surface acoustic waves between the surfaces sufficient to enable a touch on the top surface to produce a respective touch response signal between the top surface transmitting transducer to the bottom surface receiving transducer, and the bottom surface transmitting transducer to the top surface receiving transducer.

10. The apparatus of claim 9, wherein the top and bottom sensitivity is represented by the reduction in amplitude of the touch response signal to the non-touch response signal between the bottom surface transmitting transducer to the top surface receiving transducer, and the top surface transmitting transducer to the bottom surface receiving transducer.

11. The apparatus of claim 10, wherein the controller determines positional information of a touch by comparing the amplitude reductions of the touch response of the bottom surface transmitting transducer to the top surface receiving transducer, to the touch response of the top surface transmitting transducer to the bottom surface receiving transducer.

12. The apparatus of claim 11, wherein the controller determines positional information of a touch by further analyzing the amplitude changes of the touch response of the bottom surface transducer pair and of the touch response of the top surface transducer pair.

13. The system of claim 9, wherein the controller determines positional information of overlapping touches on the top surface by utilizing a comparison of the touch response signal between the top surface transmitting transducer to the bottom surface receiving transducer with the touch response signal between the bottom surface transmitting transducer to the top surface receiving transducer for each touch to distinguish between the signals of the touches and the respective positional information.

14. An acoustic touch sensor system having multi-touch capability, comprising:

a substrate that is capable in a peripheral region to propagating surface acoustic waves along substrate surfaces and in a central region to permit top-bottom oscillation of the surface acoustic waves from the one of the surfaces to the other surface through the substrate, said substrate having a top surface, a bottom surface, and a curved connecting surface formed between said top surface and said bottom surface;

a first transmitting element disposed on an outside area of the peripheral region of the bottom surface and a second transmitting element disposed on an inside area of the peripheral region of the bottom surface;

a first receiving element disposed on an outside area of the peripheral region of the bottom surface and a second receiving element disposed on an inside area of the peripheral region of the bottom surface, the set of transmitting elements and the set of receiving elements disposed on opposing sides of the central region of the substrate; and

a controller that excites the first and second transmitting elements to generate respective surface acoustic waves and that analyzes the respective signals received by the first and second receiving elements, said substrate forming at least respective wave paths from the first transmitting element, around the proximate curved connecting surface, through the substrate in the central region and to the second receiving element; and

from the second transmitting element, through the substrate in the central region, around the proximate curved connecting surface and to the first receiving element.

15. The system of claim 14, wherein each transmitting element comprises a transmitting acoustic wave transducer and an associated transmitting reflective array and each receiving element comprises a receiving acoustic wave transducer and an associated receiving reflective array.

16. The system of claim 14 further comprising another set of transmitting elements and another set of receiving elements disposed on the other two opposing sides of the central region of the substrate in a similar manner as the respective first sets, each pair of sets being utilized to define a respective axis coordinate of the front surface.

17. The system of claim 14, wherein each receiving element is adapted to produce a touch response signal for a respective touch on the top surface and the controller analyzes the touch response signals and non-touch response signals produced by each receiving element to determine axis coordinate information of the touch on the top surface from the response signals.

18. The system of claim 17, wherein the controller analyzes the ratios of signal losses of touch response signals to determine axis coordinate information of the touch on the top surface.

19. The system of claim 17, wherein the controller analyzes the delay times of touch response signals, and the ratios of signal losses of touch response signals in the top-bottom oscillation-based signals to determine axis coordinate information of the touch on the top surface.

20. The system of claim 19, wherein certain of the axis coordinate information is dependent upon the ratios of signal losses of touch response signals in the top-bottom oscillation-based signals;

and the distance between respective transmitting and receiving elements on the top and bottom surfaces.

21. The system of claim 19, further comprising another set of transmitting elements and another set of receiving elements disposed on the other two opposing sides of the central region of the substrate in a similar manner as the respective first sets, each pair of sets being utilized to define a respective axis coordinate of the front surface.

22. The system of claim 17, wherein the controller analyzes the ratios of signal level changes of touch response signals to determine axis coordinate information of the touch on the top surface.

23. The system of claim 14, wherein the substrate further has a damping material separating the peripheral region into outside and inside areas.

24. The system of claim 14, wherein the substrate is adapted to provide non-symmetrical top and bottom surfaces acoustic waves in a peripheral region in order to propagate surface acoustic waves.