Sliding bias and peak limiting for optical hearing devices

Patent metadata

Field	Value
Publication number	US-9930458-B2
Application number	US-201514813301-A
Country	US
Kind code	B2
Filing date	Jul 30, 2015
Priority date	Jul 14, 2014
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A processor comprises instructions to adjust a bias of an input signal in order to decrease a duty cycle of a pulse modulated optical signal. The bias can be increased, decreased, or maintained in response to one or more measured values of the signal. In many embodiments, a gain of the signal is adjusted with the bias in order to inhibit distortion. The bias can be adjusted slowly in order to inhibit audible noise, and the gain can be adjusted faster than the bias in order to inhibit clipping of the signal. In many embodiments, one or more of the bias or the gain is adjusted in response to a value of the signal traversing a threshold amount. The value may comprise a trough of the signal traversing the threshold.

First claim

What is claimed is:

1. A method of transmitting an audio signal to an ear of a user with light, the method comprising:
receiving the audio signal from an input;
determining a bias of the audio signal and a biased audio signal with a processor in response to the audio signal;
outputting the biased audio signal to circuitry to drive a light source with the biased signal in order to generate an optical signal with decreased light energy transmitted from the light source; and
receiving the optical signal with an output transducer to vibrate the ear in response to the output optical signal,
wherein the processor comprises instructions for a look ahead delay to decrease the gain to inhibit clipping in response to a negative signal below a threshold amount detected with the look ahead delay.

2. A method as in claim 1 , wherein the processor comprises instructions to adjust the bias to decrease light energy in response to decreased energy of the audio signal and to adjust the bias to increase light energy in response to increased energy of the audio signal in order to inhibit distortion.

3. A method as in claim 2 , wherein the processor comprises instructions to adjust the bias in a direction corresponding to negative sound pressure in response to decreased amounts of negative sound pressure of the audio signal.

4. A method as in claim 2 , wherein the processor comprises instructions to adjust the bias to decrease amounts of light energy at a first rate and to increase amounts of light energy at a second rate to inhibit distortion, the first rate slower than the second rate.

5. A method as in claim 2 , wherein the processor comprises instructions to adjust the bias over a time duration of more than about 50 ms in order to inhibit an audible thump.

6. A method as in claim 2 , wherein the processor comprises instructions to adjust the bias over a time duration of more than about 20 ms in order to inhibit an audible thump.

7. A method as in claim 1 , wherein the processor comprises instructions to adjust the biased signal to more positive values in response to the negative signal below the threshold amount and to increase the gain when the biased signal is adjusted to the more positive values.

8. A method as in claim 1 , wherein the negative signal corresponds to negative sound pressure and the threshold amount comprises a lower end of the input range.

9. A method as in claim 8 , wherein the processor comprises instructions to decrease the gain faster than a change in bias and wherein the bias remains substantially fixed when the gain is decreased in response to the signal below the threshold.

10. A method as in claim 9 , wherein the processor comprises instructions to decrease the gain over a duration no more than a length of the look ahead delay and the bias remains substantially fixed to within about five percent (5%) over the length of the look ahead delay.

11. A method as in claim 1 , wherein the processor comprises instructions to limit the bias in response to a noise floor associated with one or more of delta sigma modulation circuitry, the circuitry to drive the light source, the light source or the output transducer to receive the output signal.

12. A method as in claim 1 , wherein the audio signal comprises a fixed bias and the processor comprises instructions to determine the biased audio signal in response to the fixed bias of the audio signal.

13. A method as in claim 1 , wherein the circuitry to drive the light source comprises delta sigma modulation circuitry.

14. A method as in claim 13 , wherein the delta sigma modulation circuitry comprises one or more of pulse width modulation circuitry, pulse density modulation circuitry, or a digital to analog converter of the processor comprising the pulse density modulation circuitry.

15. A method as in claim 14 , wherein the circuitry to drive the light source comprises an analog amplifier.

16. A method of transmitting an audio signal to an ear of a user with light, the method comprising:
receiving the audio signal from an input;
determining a bias of the audio signal and a biased audio signal with a processor in response to the audio signal;
outputting the biased audio signal to circuitry to drive a light source with the biased signal in order to generate an optical signal with decreased light energy transmitted from the light source; and
receiving the optical signal with an output transducer to vibrate the ear in response to the output optical signal,
wherein the processor comprises instructions to limit the bias in response to a noise floor associated with one or more of delta sigma modulation circuitry, the circuitry to drive the light source, the light source or the output transducer to receive the output signal.

17. A method as in claim 16 , wherein the processor comprises instructions to adjust the bias to decrease light energy in response to decreased energy of the audio signal and to adjust the bias to increase light energy in response to increased energy of the audio signal in order to inhibit distortion.

18. A method as in claim 17 , wherein the processor comprises instructions to adjust the bias in a direction corresponding to negative sound pressure in response to decreased amounts of negative sound pressure of the audio signal.

19. A method as in claim 17 , wherein the processor comprises instructions to adjust the bias to decrease amounts of light energy at a first rate and to increase amounts of light energy at a second rate to inhibit distortion, the first rate slower than the second rate.

20. A method as in claim 17 , wherein the processor comprises instructions to adjust the bias over a time duration of more than about 50 ms in order to inhibit an audible thump.

21. A method as in claim 17 , wherein the processor comprises instructions to adjust the bias over a time duration of more than about 20 ms in order to inhibit an audible thump.

22. A method as in claim 16 , wherein the processor comprises instructions for a look ahead delay to decrease the gain to inhibit clipping in response to a negative signal below a threshold amount detected with the look ahead delay.

23. A method as in claim 22 , wherein the processor comprises instructions to adjust the biased signal to more positive values in response to the negative signal below the threshold amount and to increase the gain when the biased signal is adjusted to the more positive values.

24. A method as in claim 22 , wherein the negative signal corresponds to negative sound pressure and the threshold amount comprises a lower end of the input range.

25. A method as in claim 24 , wherein the processor comprises instructions to decrease the gain faster than a change in bias and wherein the bias remains substantially fixed when the gain is decreased in response to the signal below the threshold.

26. A method as in claim 25 , wherein the processor comprises instructions to decrease the gain over a duration no more than a length of the look ahead delay and the bias remains substantially fixed to within about five percent (5%) over the length of the look ahead delay.

27. A method as in claim 16 , wherein the audio signal comprises a fixed bias and the processor comprises instructions to determine the biased audio signal in response to the fixed bias of the audio signal.

28. A method as in claim 16 , wherein the circuitry to drive the light source com

Assignees

• Earlens Corp

Inventors

• Freed Daniel J
• Puria Sunil

Classifications

• H04B10/114

  Indoor or close-range type systems · CPC title

• H04B10/50595

  to control the modulator DC bias · CPC title

• H04R2225/49

  Reducing the effects of electromagnetic noise on the functioning of hearing aids, by, e.g. shielding, signal processing adaptation, selective (de)activation of electronic parts in hearing aid · CPC title

• H04R2225/33

  Aspects relating to adaptation of the battery voltage, e.g. its regulation, increase or decrease · CPC title

• H04R25/554 Primary

  using a wireless connection, e.g. between microphone and amplifier or using Tcoils · CPC title