SIGNAL PROCESSING FOR ACOUSTIC USER INPUT

• US 20150002478A1
• Filed: 09/18/2014
• Published: 01/01/2015
• Est. Priority Date: 03/21/2012
• Status: Active Grant

• Current Assignee: Elliptic Laboratories AS
• Original Assignee: Elliptic Laboratories AS
• Inventors: BANG, Hans Jrgen, DAHL, Tobias Gulden
• Granted Patent: US 9,582,121 B2
• Time in Patent Office: Days
• US Class Current: 345/177
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 3/017 Gesture based interaction, e.g. based on a set of recognized hand gestures interaction based on gestures traced on a digitiser G06F3/04883
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/043 using propagating acoustic waves

Abstract

An electronic apparatus has a transmitter arranged to transmit an acoustic signal. It also has a receiver, for receiving acoustic energy comprising a reflection of the acoustic signal from an input object. It generates an electronic received signal from the received acoustic energy. The apparatus has processing means arranged to: (i) analyse at least a portion of the received signal to determine a linear combination of basis functions which represents an interference component in the received signal; (ii) use the determined linear combination to attenuate interference within the received signal, to give a post-attenuation signal; and (iii) use the post-attenuation signal to determine a user input to the electronic apparatus.

Claims

1. An electronic apparatus comprising:

a transmitting arrangement, arranged to transmit an acoustic signal;

a receiving arrangement, arranged to receive acoustic energy comprising a reflection of the acoustic signal from an input object, and to generate an electronic received signal therefrom; and

a processing arrangement, arranged to;

analyse at least a portion of the received signal to determine a linear combination of basis functions which represents an interference component in the received signal;

use the determined linear combination to attenuate interference within the received signal, to give a post-attenuation signal; and

use the post-attenuation signal to determine a user input to the electronic apparatus.

2. An electronic apparatus as claimed in claim 1, configured to determine what basis functions to use in said analysis by first analysing at least a portion of the received signal.

3. An electronic apparatus as claimed in claim 2, wherein said basis-determining portion is a portion of the received signal that contains substantially none of the transmitted acoustic signal, nor any discernible reflections thereof.

4. An electronic apparatus as claimed in claim 1, wherein said portion of the received signal used to determine a linear combination of basis function contains substantially no energy arising from transmissions from the electronic apparatus.

5. An electronic apparatus as claimed in claim 1, wherein the basis functions are a cosine function and a sine function.

6. An electronic apparatus as claimed in claim 1, wherein the basis functions are a subset from the discrete Fourier transform basis.

7. An electronic apparatus as claimed in claim 1, wherein a set of basis functions is preconfigured for the apparatus, and wherein the apparatus is arranged to access these basis functions prior to determining the linear combination.

8. An electronic apparatus as claimed in claim 1, configured to access a plurality of different sets of basis functions, and to select one set of basis functions to use when determining the linear combination.

9. An electronic apparatus as claimed in claim 8, wherein the sets of basis functions include differently time-shifted versions of a pattern of transmissions used by another device.

10. An electronic apparatus as claimed in claim 8, wherein at least some of the sets of basis functions are associated with respective patterns of interference, and wherein the electronic apparatus is configured to select a set of basis functions by determining the presence, in a portion of the received signal, of a pattern of interference associated with that set.

11. An electronic apparatus as claimed in claim 10, configured to test a number of hypotheses about what pattern of interference may be present in the signal, and to determine a best hypothesis according to a predetermined best-fit criterion.

12. An electronic apparatus as claimed in claim 1, wherein the apparatus is configured to generate a set of basis functions.

13. An electronic apparatus as claimed in claim 12, configured to calculate a singular value decomposition of a matrix that represents a basis-determining portion of the received signal.

14. An electronic apparatus as claimed in claim 1, wherein the basis functions are mutually orthogonal.

15. An electronic apparatus as claimed in claim 1, configured to use the same basis functions to determine a plurality of successive linear combinations representing respective successive interference components in the received signal.

16. An electronic apparatus as claimed in claim 1, configured to determine or select updated basis functions continually or at intervals.

17. An electronic apparatus as claimed in claim 1, configured to determine new basis functions on detecting a change in the value of a frequency component in the received acoustic energy, and to use the new basis functions in determining a linear combination of the new basis functions which represents a further interference component in a later received signal-portion or signal.

18. An electronic apparatus as claimed in claim 1, comprising a memory storing information relating to a finite number of frequency states, and configured to detect the presence of one of the stored frequency states in the received signal, and to respond by changing basis functions.

19. An electronic apparatus as claimed in claim 1, wherein the signal is an ultrasonic signal.

20. An electronic apparatus as claimed in claim 1, configured to determine the linear combination as a combination which matches the interference component according to a predetermined match criterion.

21. An electronic apparatus as claimed in claim 1, configured to attenuate interference within the received signal by subtracting the linear combination from the received signal.

22. An electronic apparatus as claimed in claim 1, configured to attenuate interference within the received signal by:

determining a subset of the basis functions, being those basis functions that have zero coefficients in said linear combination; and

representing at least a portion of the received signal as a linear combination of this subset of the basis functions.

23. An electronic apparatus as claimed in claim 1, configured to attenuate interference from a portion of the received signal that contains reflections from the input object.

24. A method of determining a user input to an electronic apparatus, the method comprising:

transmitting an acoustic signal;

receiving acoustic energy comprising a reflection of the acoustic signal from an input object;

generating an electronic received signal from the received acoustic energy;

analysing at least a portion of the received signal to determine a linear combination of basis functions which represents an interference component in the received signal

using the determined linear combination to attenuate interference within the received signal, to give a post-attenuation signal; and

using the post-attenuation signal to determine a user input to the electronic apparatus.

25. A software product comprising instructions which, when executed on an electronic apparatus, cause the electronic apparatus to:

analyse at least a portion of an electronic received signal to determine a linear combination of basis functions which represents an interference component in the received signal, where the received signal has been generated from received acoustic energy, comprising a reflection of an acoustic signal from an input object;

use the determined linear combination to attenuate interference within the received signal, to give a post-attenuation signal; and

use the post-attenuation signal to determine a user input.