Methods and apparatus to monitor haptic vibrations of touchscreens

1. An apparatus comprising:

a haptic signal generator to obtain a surface haptic control signal that is to cause a touchscreen to vibrate to generate a perception of a texture for a user interacting with the touchscreen, the texture corresponding to content displayed on the touchscreen, vibrations of the touchscreen to produce an acoustically detectable signal; and

a watermark encoder to encode a watermark into the surface haptic control signal to generate a watermarked surface haptic control signal, the watermark including identifying information to identify the content, the watermark to modify the acoustically detectable signal.

2. The apparatus as defined in claim 1 , further including a communications interface to transmit the watermarked surface haptic control signal to a computing device, the computing device including the touchscreen.

3. The apparatus as defined in claim 1 , further including the touchscreen.

4. The apparatus as defined in claim 3 , further including a surface haptic controller to vibrate the touchscreen based on the watermarked surface haptic control signal.

5. The apparatus as defined in claim 1 , wherein the watermark encoder encodes the watermark into the surface haptic control signal by modifying the surface haptic control signal to cause vibrations based on at least one of different frequencies or different amplitudes for defined durations.

6. The apparatus as defined in claim 1 , wherein the watermark encoder encodes the watermark into the surface haptic control signal using a modulated signal with an amplitude that is a function of time.

7. The apparatus as defined in claim 1 , wherein differences in vibrations caused by the surface haptic control signal and the watermarked surface haptic control signal are not discernable by human touch.

8. The apparatus as defined in claim 1 , wherein the watermark is detectable using a sensor monitoring an acoustic the acoustically detectable signal generated by the vibrations of the touchscreen.

9. The apparatus as defined in claim 1 , wherein the watermarked surface haptic control signal is to cause the touchscreen to vibrate with ultrasonic vibrations, and the watermark is detectable using an ultrasonic sensor monitoring the acoustically detectable signal produced by the ultrasonic vibrations of the touchscreen.

10. A method comprising:

generating, by executing an instruction with a processor, a surface haptic control signal that is to cause a touchscreen to vibrate to generate a sensation of a texture for a user interacting with the touchscreen, the texture corresponding to content displayed on the touchscreen, vibrations of the touchscreen to produce an acoustically detectable signal; and

encoding, by executing an instruction with the processor, a watermark into the surface haptic control signal to generate a watermarked surface haptic control signal, the watermark including identifying information to identify the content, the watermark to modify the acoustically detectable signal.

11. The method as defined in claim 10 , further including transmitting the watermarked surface haptic control signal to a computing device, the computing device including the touchscreen.

12. The method as defined in claim 10 , wherein the processor and the touchscreen correspond to a same computing device.

13. The method as defined in claim 12 , further including vibrating the touchscreen based on the watermarked surface haptic control signal.

14. The method as defined in claim 10 , further including encoding the watermark into the surface haptic control signal by modifying the surface haptic control signal to cause vibrations based on at least one of different frequencies or different amplitudes for defined durations.

15. A non-transitory computer readable medium comprising instructions that, when executed, cause a processor to at least:

generate a surface haptic control signal that is to cause a touchscreen to vibrate to generate a sensation of a texture for a user interacting with the touchscreen, the texture corresponding to content displayed on the touchscreen, vibrations of the touchscreen to produce an acoustically detectable signal; and

encode a watermark into the surface haptic control signal to generate a watermarked surface haptic control signal, the watermark including an identifier to be mapped to identifying information for the content, the watermark to modify the acoustically detectable signal.

16. The non-transitory computer readable medium as defined in claim 15 , wherein the instructions further cause the processor to transmit the watermarked surface haptic control signal to a computing device, the computing device including the touchscreen.

17. The non-transitory computer readable medium as defined in claim 15 , wherein the processor and the touchscreen are part of a single device.

18. The non-transitory computer readable medium as defined in claim 17 , wherein the instructions further cause the processor to vibrate the touchscreen based on the watermarked surface haptic control signal.

19. The non-transitory computer readable medium as defined in claim 15 , wherein the instructions further cause the processor to encode the watermark into the surface haptic control signal by modifying the surface haptic control signal to cause vibrations at different frequencies for defined durations.

20. The non-transitory computer readable medium as defined in claim 15 , wherein differences in vibrations caused by the surface haptic control signal and the watermarked surface haptic control signal are not discernable by human touch.