LED CONTROL UTILIZING AMBIENT LIGHT OR SIGNAL QUALITY

• US 20090299675A1
• Filed: 06/02/2009
• Published: 12/03/2009
• Est. Priority Date: 06/03/2008
• Status: Active Application

• Current Assignee: Nonin Medical Incorporated
• Original Assignee: Nonin Medical Incorporated
• Inventors: Schilling, Josh D., Isaacson, Philip O.
• Granted Patent: US 10,271,778 B2
• Time in Patent Office: Days
• US Class Current: 702/104
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7242 using integration

Abstract

A system and method for controlling a light emitting device for an optical sensor based on signal quality and/or power consumption requirements. Drive current and/or integration time is controlled as a function of detected ambient light or signal quality. As the signal quality decreases the drive current or integration time can be adjusted to provide a more usable signal. If after some criteria for reduction, such as “time on” or high signal quality, then the drive current can be decreased.

Claims

1. A device comprising:

a sensor having a light emitter and having a detector configured to provide an output corresponding to an optical property of tissue using light from the emitter;

a processor coupled to the sensor and configured to determine a value corresponding to a signal to noise ratio for the output and configured to compare the value with a threshold; and

a control unit coupled to the processor and configured to adjust power supplied to the sensor based on the comparison.

2. The device of claim 1 wherein the emitter is configured to emit light having at least one of a near infrared range and a red range.

3. The device of claim 1 wherein the emitter includes at least one of a light emitting diode and a vertical-cavity surface-emitting laser (VCSEL).

4. The device of claim 1 wherein the processor is configured to determine a measure of ambient noise.

5. The device of claim 1 wherein the processor is configured to determine a measure of shot noise.

6. The device of claim 1 wherein the processor is configured to determine a measure of electronic noise.

7. The device of claim 1 wherein the processor is configured to determine a measure of at least one of thermal fluctuations and circuit flicker.

8. The device of claim 1 wherein the control unit is configured to adjust power by adjusting intensity of the emitted light.

9. The device of claim 1 wherein the control unit is configured to adjust power by adjusting a time of the emitted light.

10. The device of claim 1 wherein the control unit is configured to adjust power by adjusting an acquisition time of the detector.

11. A method comprising:

emitting light from a device configured to measure a parameter of a tissue using an optical property of the tissue;

measuring a light signal corresponding to the emitted light;

using a processor to determine a value corresponding to a signal to noise ratio for the light signal;

comparing the value with a threshold; and

adjusting power consumption of the device based on the comparison.

12. The method of claim 11 wherein emitting light includes emitting radiation in at least one of a near infrared range and a red range.

13. The method of claim 11 wherein emitting light includes emitting using at least one of a light emitting diode and a vertical-cavity surface-emitting laser (VCSEL).

14. The method of claim 11 wherein measuring the light signal includes generating a signal using a light detector.

15. The method of claim 11 wherein using the processor to determine the value includes measuring ambient noise.

16. The method of claim 11 wherein using the processor to determine the value includes measuring shot noise.

17. The method of claim 11 wherein using the processor to determine the value includes measuring electronic noise.

18. The method of claim 11 wherein measuring electronic noise includes measuring at least one of thermal fluctuations and circuit flicker.

19. The method of claim 11 wherein adjusting power consumption includes adjusting intensity of the emitted light.

20. The method of claim 11 wherein adjusting power consumption includes adjusting a time of the emitted light.

21. The method of claim 11 wherein adjusting power consumption includes adjusting an acquisition time for measuring the parameter.

22. A system comprising:

an emitter configured to emit light;

a detector configured to provide an output corresponding to a measured light signal based on an optical property of tissue and the emitted light;

a processor coupled to the detector and configured to determine a value corresponding to a measure of quality of the light signal and configured to compare the value with a threshold; and

a control unit configured to adjust power consumption based on the comparison.

23. The system of claim 22 wherein the measure of quality includes at least one of signal power level, signal amplitude, and signal to noise ratio.

24. The system of claim 22 wherein the emitter is configured to emit light having at least one of a near infrared range and a red range.

25. The system of claim 22 wherein the emitter includes at least one of a light emitting diode and a vertical-cavity surface-emitting laser (VCSEL).

26. The system of claim 22 wherein the processor is configured to receive a measure of ambient noise.

27. The system of claim 22 wherein the processor is configured to receive a measure of shot noise.

28. The system of claim 22 wherein the processor is configured to receive a measure of electronic noise.

29. The system of claim 22 wherein the processor is configured to receive a measure of at least one of thermal fluctuations and circuit flicker.

30. The system of claim 22 wherein the control unit is coupled to at least one of an amplifier and a driver.

31. The system of claim 30 wherein the amplifier includes an integration amplifier coupled to the detector.

32. The system of claim 30 wherein the driver is coupled to the light emitter.

33. The system of claim 32 wherein the control unit is configured to adjust power supplied to the driver.

34. The system of claim 22 wherein the control unit is configured to adjust power by adjusting an acquisition time of the emitted light.