Method for determining the locations of at least two impacts

• US 8,237,676 B2
• Filed: 12/19/2008
• Issued: 08/07/2012
• Est. Priority Date: 12/21/2007
• Status: Active Grant

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touch Solutions, Inc.
• Inventors: Duheille, Remi, Schevin, Olivier, Ing, Ros Kiri
• Primary Examiner(s): Olson, Jason
• Application Number:
  US12/339,874
• Publication Number:
  US 20090195517A1
• Time in Patent Office: 1,327 Days
• Field of Search: None
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04808 Several contacts: gestures triggering a specific function, e.g. scrolling, zooming, right-click, when the user establishes several contacts with the surface simultaneously; e.g. using several fingers or a combination of fingers and pen
• CPC Class Codes: G06F 3/043 using propagating acoustic waves

Abstract

A method for determining the locations of at least two impacts F₁ and F₂ on a surface using one or more sensors S_i, i=1 to n, with n being the number of sensors, and the impacts F₁ and F₂ generating a signal being sensed by the one or more sensors, wherein each sensor provides a sensed signal s_i(t), i=1 to n, with n being the number of sensors. To be able to determine simultaneous impacts of different amplitudes the method includes identifying the location x of one impact, and determining a modified sensed signal s_i′(t) for each sensor in which the contribution due to the identified impact is reduced and which is based on a comparison, in particular a correlation, of each of the sensed signals s_i(t) and a predetermined reference signal r_ij(t) corresponding to a reference impact R_j at location j. The method can also be based on couples of sensed signals.

Claims

1. Method for determining the locations of at least two impacts F₁ and F₂ on a surface using one or more sensors S_i, i=1 to n, with n being the number of sensors, the impacts F₁ and F₂ generating a signal being sensed by the one or more sensors, wherein each sensor provides a sensed signal s_i(t), i=1 to n, with n being the number of sensors;

and comprising;

a) identifying the location x of one impact, and

b) determining a modified sensed signal s_i′

(t) for each sensor in which the contribution due to the identified impact is reduced and which is based on a comparison of each of the sensed signals s_i(t) and a predetermined reference signal r_ij(t) corresponding to a reference impact R_j at a reference location j.

2. Method according to claim 1, wherein the locations of the at least two impacts on the surface define a trajectory of a continuous impact on the surface.

3. Method according to claim 2, wherein the first and second impact correspond to successive positions on the trajectory.

4. Method according to claim 1, wherein the sensor is an acoustic sensor.

5. Method according to claim 1, wherein identifying the location x of one impact is of the strongest impact.

6. Method according to claim 5, wherein the comparison is a correlation.

7. Method according to claim 6 wherein b) comprises:

b1) correlating each of the sensed signals s_i(t) with the reference signal r_ix(t), which is the reference signal, out of a plurality of reference signals r_ij(t) corresponding to a series of reference impacts provided at a certain number of reference positions R_j, which corresponds to a reference impact in the vicinity of the location x of a strongest impact,

b2) fitting each correlation product with a predetermined function and

b3) subtracting the fitted function from the correlation product.

8. Method according to claim 7, wherein the correlating of each of the sensed signals s_i(t) with the reference signal r_ix(t) is performed by using the Fourier transform S_i(ω

) of the sensed signal s_i(t) and the Fourier transform R_ix(ω

) of the reference signal r_ix(t).

9. Method according to claim 8, wherein b) further comprises, multiplying the results obtained with the Fourier transform R_ix(ω

) of the reference signal r_ix(t) to thereby obtain a modified Fourier transform S_i′

(ω

) corresponding to a modified sensed signal s_i′

(t).

10. Method according to claim 9, and further comprising c) identifying the location of the next weaker second impact using the modified sensed signals s_i′

(t) or its Fourier transform S_i′

(ω

), wherein c) comprises;

determining the correlations of the modified sensed signals s_i′

(t) of each sensor with each reference signal r_ij(t), and averaging the correlation products over the sensors for each reference signal r_ij(t).

11. Method according to claim 10, wherein a) to c) are repeated to identify the location of the next weaker impact, wherein in each time in a) the location of the impact which has been identified in the previous run is taken as strongest location x and in b) a new modified sensed signal is determined out of the determined modified sensed signal of the previous run.

12. Method according to claim 10, wherein determining the correlation is performed by using the Fourier transforms S_i′

(ω

) and R_ij(ω

).

13. Method according to claim 10, wherein averaging the correlation product is performed in the time domain.

14. Method according to claim 7, wherein the reference impact is closest to the location x of the strongest impact.

15. Method according to claim 7, wherein the predetermined function is a complex exponential function.

16. Method according to claim 6, wherein b) comprises:

b1) correlating each of the Fourier transforms S_i(ω

) of the sensed signals s_i(t) with the Fourier transform R_ix(ω

) of the reference signal r_ix(t), which is the reference signal, out of a plurality of reference signals r_ij(t) corresponding to a series of reference impacts provided at a certain number of reference positions R_j, which corresponds to a reference impact in the vicinity of the location x of a strongest impact, thereby obtaining n correlation products S_i(ω

)_R_ix*(ω

), with R_ix*(ω

) being the complex conjugate of the Fourier transform R_ix(ω

),

b2) averaging the correlation products S_i(ω

)_R_ix*(ω

) over the n sensors,

b3) determining the phase of the average of the n correlation products S_i(ω

)_R_ix*(ω

),

b4) multiplying each of the correlation products S_i(ω

)_R_ix*(ω

) with the complex conjugate of the phase of the average to thereby obtain modified correlation products,

b5) subtracting the real part from the modified correlation products, and

b6) multiplying each of the remaining part of the modified correlation products with the phase of the average.

17. Method according to claim 16, wherein the reference signal is closest to the location x of the strongest impact.

18. A method for determining the locations of at least two impacts F₁ and F₂ on a surface using one or more sensors S_i, i=1 to n, with n being the number of sensors, and the impacts F₁ and F₂ generating a signal being sensed by the one or more sensors, wherein each sensor provides a sensed signal s_i(t), i=1 to n, with n being the number of sensors and comprising:

a) identifying the location x of one impact, and

b) determining a modified signal based on the sensed signal s_i(t) in which the contribution of the identified impact is reduced and which is furthermore based on a comparison of pairs of sensed signals s_i(t) and s_i′

(t) and pairs of corresponding predetermined reference signals r_ij(t) and r<sub>i′

j</sub>(t) corresponding to a reference impact R_j at a reference location i.

19. Method according to claim 18, wherein identifying the location x of one impact is of the strongest impact.

20. Method according to claim 19, and wherein the comparison is a correlation.

21. Method according to claim 20, wherein b) comprises:

b1) correlating the Fourier transforms S_i(ω

) and S_i′

(ω

) of two sensed signals s_i(t) and s_i′

(t) thereby obtaining a first correlation product S_i(ω

)_S_i′

*(ω

), with S_i′

*(ω

) being the complex conjugate of the Fourier transform S_i′

(ω

),

b2) correlating the Fourier transforms R_ix(ω

) and R<sub>i′

x</sub>(ω

) of the corresponding reference signals r_ix(t) and r<sub>i′

x</sub>(t), r_ix(t) and r<sub>i′

x</sub>(t) being the reference signals which correspond to a reference impact in the vicinity of the strongest impact x, thereby obtaining a second correlation product R_ix*(ω

) R<sub>i′

x</sub>(ω

) with R_ix*(ω

) being the complex conjugate of the Fourier transform R_ix(ω

),

b3) correlating the first and second correlation products to obtain a third correlation product S_i(ω

) S_i′

*(ω

) R_ix*(ω

) R_ix′

(ω

),

b4) averaging the real part of the third correlation product over all pairs of sensor couples and subtracting this average from the third correlation products to obtain P<sub>ii′

x</sub>(ω

).

22. Method according to claim 21, further comprising c) identifying the location of the next weaker second impact, comprising:

multiplying P<sub>ii′

x</sub>(ω

) with the sum of R_ix(ω

) R_im*(ω

)+_R<sub>i′

x</sub>*(ω

) R<sub>i′

m</sub>(ω

) for all reference impacts R_m, m=1 to P, with P being the number of reference impacts at reference locations m, and for all sensor couples S_i and S_i′

, with R_im(ω

) and R<sub>i′

m</sub>(ω

) being the Fourier transforms of reference signal r_im(t) and r<sub>i′

m</sub>(t), and R_im*(ω

) and R<sub>i′

x</sub>*(ω

) being the complex conjugates of Fourier transforms R_im(ω

)+R<sub>i′

x</sub>(ω

),

Fourier transforming each one of the products, and

summing the negative time part to the positive time part of each Fourier transform.

23. Method according to claim 22, wherein c) further comprises averaging the obtained sums for all sensor couples S_i and S_i′

.

24. Method according to claim 23, wherein the averaging of the obtained sums is performed in the time domain.

25. Method according to claim 21, wherein in the vicinity of the strongest impact is closest to the location x of the strongest impact.

26. Method according to claim 25, wherein a) to c) are repeated to identify the location of the next weaker impact, wherein each time in a) the location of the impact which has been identified in c) of the previous run is taken as strongest location x and in b) a new modified signal is determined out of the determined modified signal of the previous run.

27. Method according to claim 21, wherein a) comprises

correlating the Fourier transforms S_i(ω

) and S_i′

(ω

) of two sensed signals s_i(t) and s_i′

(t) thereby obtaining the first correlation product S_i(ω

) S_i′

(ω

)*,

correlating the Fourier transforms R_im and R<sub>i′

m</sub>(ω

) of two corresponding reference signals r_im(t) and r<sub>i′

m</sub>(t), m=1 to P, with P being the number of reference impacts at reference locations m, thereby obtaining second correlation products R_im*(ω

) R<sub>i′

m</sub>(ω

), R_im*(ω

) being the complex conjugate of Fourier transform R_im(ω

),

correlating the first and second correlation products to obtain the third correlation product S_i(ω

) S_i′

*(ω

) R_im*(ω

) R<sub>i′

m</sub>(ω

), and

averaging the correlation products over the couples of sensors S_i and S_i′

.

28. Method according to claim 27, wherein the averaging of the correlation products is performed in the time domain.

29. Method according to claim 20, wherein a) comprises:

determining the correlations of the sensed signal s_i(t) of each sensor with each reference signal r_ij(t), and

averaging the correlation products over the sensors for each reference signal r_ij(t).

30. Method according to claim 29, wherein determining the correlations is performed using the Fourier transforms S_i(ω

) and R_ij(ω

).

31. Method according to claim 29, wherein the averaging of the correlation products is performed in the time domain.

32. Method according to claim 18, wherein the locations of the at least two impacts on the surface define a trajectory of a continuous impact on the surface.

33. Method according to claim 18, wherein the sensor is an acoustic sensor.

34. Computer program product, comprising one or more non-transitory computer readable media having computer-executable instructions adapted to perform the following:

a) identify the location x of one impact, and

b) determine a modified sensed signal s_i′

(t), i=1 to n, with n being the number of sensors, for each sensor in which the contribution due to the identified impact is reduced and which is based on a comparison of each of the sensed signals s_i(t) and a predetermined reference signal r_ij(t) corresponding to a reference impact R_j at location j.

35. A device for determining the locations of at least two impacts F₁ and F₂ on a surface comprising:

a processing unit, and

one or more sensors configured and arranged to transmit a sensed signal being the result of the at least two impacts to the processing unit,

wherein the processing unit is configured and arranged to;

a) identify the location x of one impact, and

b) determine a modified sensed signal s_i′

(t), i=1 to n, with n being the number of sensors, for each sensor in which the contribution due to the identified impact is reduced and which is based on a comparison of each of the sensed signals s_i(t) and a predetermined reference signal r_ij(t) corresponding to a reference impact R_j at location j.