Contact sensitive device

• US 20050165564A1
• Filed: 03/21/2005
• Published: 07/28/2005
• Est. Priority Date: 12/06/2002
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: New Transducers Limited (Alphabet Inc.)
• Inventors: Roland Hill, Nicholas Patrick, Sullivan, Darius Martin
• Granted Patent: US 7,184,898 B2
• Time in Patent Office: Days
• US Class Current: 702/56
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/043 using propagating acoustic waves
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

A contact sensitive device includes a member capable of supporting bending waves and a plurality of sensors mounted on the member for measuring bending wave vibration in the member. The sensors measure the bending wave signals and by calculating a phase angle for each measured bending wave signal and a phase difference between the phase angles of least two pairs of sensors so that at least two phase differences are calculated, the location of the contact can be determined.

Claims

1. A contact sensitive device comprising:

a member capable of supporting bending waves;

a plurality of sensors for measuring bending wave vibration in the member, wherein each of the sensors determines a measured bending wave signal; and

a processor responsive to the measured bending wave signals to calculate a location of a contact on the member, the processor calculating a phase angle for each measured bending wave signal and a phase difference between the phase angles of at least two pairs of sensors so that at least two phase differences are calculated and utilized in determining the location of the contact, wherein the phase difference between the phase angles of each pair of sensors is given by

Δ

θ

_lm=θ

_l−

θ

_m=k(ω

₀)Δ

x_lm+π

n_lm

 

where θ

_i is the phase angle of a measured bending wave signal, x_i is the distance from the contact location to each sensor, Δ

x_lm=x_l−

x_m is a path length difference of two sensors, k(ω

) is a wavevector and n_lm is an integer.

2. A contact sensitive device according to claim 1 wherein the member is an input device for a graphical user interface and the processor is adapted to utilize information about expected contact location in calculation of the location of the contact.

3. A contact sensitive device according to claim 2 where the graphical user interface presents a user with a choice of button locations to contact and the processor assumes that any contact on the member occurs within the button locations in determining the location of the contact.

4. A contact sensitive device according to claim 2 wherein probability of where a contact is likely to occur is utilized in determining the location of the contact.

5. A contact sensitive device according to claim 4 wherein the probability is based on one or more of location, size, and frequency of use of objects presented by the graphical user interface device.

6. A contact sensitive device according to claim 1 wherein sensors are piezoelectric vibration sensors.

7. A contact sensitive device according to claim 1 wherein a single value of the path length difference is determined for each pair of sensors and an intersection of two hyperbolae defined by the two path length differences defines the contact location.

8. A contact sensitive device according to claim 7 further comprising a plurality of band pass filters, and wherein the bending wave signal measured by each sensor is processed by two band-pass filters and two phase angles for each sensor are calculated and two phase angle differences are provided for each pair of sensors.

9. A method of determining information relating to a contact on a contact sensitive device comprising:

providing a member capable of supporting bending waves and a plurality of sensors for measuring bending wave vibration in the member;

measuring a bending wave signal using each of the sensors in response to a contact being applied to the member at a location;

determining a phase angle for each measured bending wave signal;

calculating a phase difference between the phase angles of at least two pairs of sensors; and

determining the location of the contact utilizing the at least two calculated phase differences.

10. A method according to claim 9 further comprising utilizing information about expected contact location in determining the location of the contact.

11. A method according to claim 10 where the member is a graphical user interface and presents a user with a choice of button locations to contact and the method further comprises assuming that any contact on the member occurs within the button locations in determining the location of the contact.

12. A method according to claim 10 further comprising utilizing probability of a contact occurring at a particular location in determining the location of the contact.

13. A method according to claim 12 wherein the probability of the contact occurring at the particular location is based on one or more of location, size, and frequency of use of objects presented by the graphical user interface.

14. The method as recited in claim 9 wherein the phase difference between the phase angles of each pair of sensors is given by Δ

θ

_lm=θ

_l−

θ

_m=k(ω

₀)Δ

x_lm+2π

n_lm, where θ

_i is the phase angle of a measured bending wave signal, x_i is the distance from the contact location to each sensor, Δ

x_lm=x_l−

x_m is a path length difference of two sensors, k(ω

) is a wavevector and n_lm is an integer, and the method further comprises using a state-space estimator to evaluate the likelihood of successive sequences of n_lm, and selecting one of the sequences having a maximum measure of likelihood.

15. The method as recited in claim 14 further comprising the state-space estimator utilizing a sequence of a pair of path-length differences taken at different times to estimate position and velocity of the contact at the different times.

16. The method as recited in claim 15 further comprising choosing a correct sequence of integers, n_lm, for which the state-space estimator gives a maximum measure of likelihood.

17. The method as recited in claim 15 wherein the state-space estimator uses a random walk as a statistical description of motion of the contact.

18. A method for determining a location of a contact on a member capable of supporting bending waves, the member having a plurality of sensors for measuring bending wave vibration in the member, the method comprising:

measuring bending wave signals at each of the sensors in response to the contact being applied to the member at the location;

determining the location of the contact using at least one path length difference for each sensor pair of at least two sensor pairs, the at least one path length difference of each sensor pair being determined according to a phase angle difference the bending wave signals measured by each sensor of the sensor pair.

19. A method as recited in claim 18 wherein a single value of the path length difference is determined for each sensor pair and an intersection of two hyperbolae defined by the at least two path length differences defines the location of the contact.

20. A method as recited in claim 19 further comprising processing the bending wave signal measured by each sensor using separate band-pass filters, calculating two phase angles for the bending wave signal measured by each sensor, respective phase angles corresponding to each band-bass filter, and providing two phase angle differences for each sensor pair, the two phase angle differences for each sensor pair being used to calculate the single value of the path length difference for each sensor pair.