Touch Sensitive Device

• US 20120050230A1
• Filed: 03/30/2010
• Published: 03/01/2012
• Est. Priority Date: 04/09/2009
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: New Transducers Limited (Alphabet Inc.)
• Inventors: Harris, Neil John
• Granted Patent: US 9,870,094 B2
• Time in Patent Office: Days
• US Class Current: 345/178
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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

A method of calibrating a touch sensitive device comprising a touch-sensitive screen; a plurality of transducers mounted to the screen and a processor, the method comprising inputting a signal into the screen at a test position on the screen whereby the screen is excited into vibration; detecting vibration in the screen using the plurality of transducers; and processing, in the processor of the touch-sensitive device, the detected vibration to generate an output signal for each of the plurality of transducers whereby when the transducers are driven by the output signals the screen is excited to generate a desired haptics sensation at the test position.

Claims

1. A method of calibrating a touch sensitive device comprising a touch-sensitive screen;

a plurality of transducers mounted to the screen and a processor, the method comprising inputting a signal into the screen at a test position on the screen whereby the screen is excited into vibration;

detecting vibration in the screen using the plurality of transducers; and

processing, in the processor of the touch-sensitive device, the detected vibration to generate an output signal for each of the plurality of transducers whereby when the transducers are driven by the output signals the screen is excited to generate a desired haptics sensation at the test position.

2. A method according to claim 1, wherein the processing comprises processing the detected vibration to measure a transfer function of the input signal for each of the plurality of transducers.

3. A method according to claim 2, wherein the processing comprises inferring an inverse transfer function for each of the plurality of transducers from the measured transfer functions and generating the output signals for each of the plurality of transducers from the associated inverse transfer functions.

4. A method according to claim 3, wherein the inferring comprises directly calculating each inverse transfer function by inverting the transfer function of the input signal.

5. A method according to claim 3, wherein the inferring comprises using feedback adaptive filter techniques to implicitly invert the transfer function of the input signal.

6. A method according to claim 3, wherein the inferring comprises using heuristic methods.

7. A method according to claim 3, comprising storing the inferred inverse transfer functions.

8. A method according to claim 1, wherein the processing comprises generating the output signal by filtering the detected signal using a time-reversed response.

9. A method according to claim 8, wherein the filtering step comprises approximating said time-reversed response by adding a fixed delay which is at least as long as the duration of the detected signal.

10. A method according to claim 9, wherein the fixed delay is at least 5 ms

11. A method according to claim 9, wherein the fixed delay is at least 10 ms

12. A method according to claim 8, comprising normalising the detected signal before filtering.

13. A method according claim 1, comprising selecting a test position and wherein the processing comprises determining output signals for each of the plurality of transducers so that a maximum haptics sensation is provided at the selected test position.

14. A method according to claim 1, comprising selecting a test position and wherein the processing comprises determining output signals for each of the plurality of transducers so that a minimum haptics sensation is provided at the selected test position.

15. A touch sensitive device configured to operate in a use mode or a calibration mode, the device comprising a touch-sensitive screen;

a plurality of transducers mounted to the screen wherein the plurality of transducers are configured, when the device is operating in use mode, to generate an output signal which excites the screen and wherein the plurality of transducer are configured, in calibration mode, to detect vibration in the screen generated by an input signal from a vibration generator contacting the screen at a test position, and a processor coupled to the multiple transducers whereby the processor is configured to process the detected vibration to generate an output signal for each of the plurality of transducers whereby, in use mode, the plurality of transducers excite the screen to produce a desired haptics sensation to a user contacting the screen at the test position.

16. A touch sensitive device according to claim 15, wherein the plurality of transducers are reciprocal transducers.

17. A touch sensitive device according to claim 16, wherein the processor is configured to process the detected vibration to measure a transfer function of the input signal at each of the plurality of transducers, to infer an inverse transfer function from each measured transfer function and to generate each output signal using the appropriate inverse transfer function.

18. A method of calibrating a touch sensitive device comprising a touch-sensitive screen;

a plurality of vibration transducers coupled to the screen, and a signal processor, the arrangement being such that at least some of the plurality of transducers provide haptic feedback to the screen in response to touch, the method comprising inputting a vibrational signal into the screen at a test position on the screen whereby the screen is excited into vibration;

detecting vibration in the screen using signals from the plurality of transducers in response to the vibrational signal;

measuring, in the signal processor the detected signals to generate an output signal for each of the plurality of transducers whereby the transducers are driven by the output signals to excite the screen to generate a desired haptics sensation at the test position, and wherein the output signals are generated by filtering the detected signals by using time inverted copies of the detected signals.

19. A method according to claim 18, wherein the time inverted copies include adding a fixed delay which is at least as long as the duration of the detected signal.

20. A method according to claim 19, wherein the fixed delay is at least 5 ms

21. A method according to claim 19, wherein the fixed delay is at least 10 ms

22. A method according to claim 18, comprising normalising the detected signal before filtering.