SYSTEM AND METHOD OF DETERMINING LIGHT SOURCE AGING

• US 20100145645A1
• Filed: 12/09/2008
• Published: 06/10/2010
• Est. Priority Date: 12/09/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Gonopolskiy, Oleg, Anderson, Arik, Widman, Ronald A., Barrett, Bruce J.
• Granted Patent: US 9,404,961 B2
• Time in Patent Office: Days
• US Class Current: 702/65
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: G01R 31/2635 Testing light-emitting diodes, laser diodes or photodiodes
• CPC Class Codes: H05B 47/20 Responsive to malfunctions or to light source life; for protection

Abstract

A physiological sensor includes a light source and an age detector circuit in communication with the light source. The age detector circuit is configured to determine an age of the light source based on current-voltage characteristics of said light source. In addition, a method includes measuring an initial I-V characteristic and an actual I-V characteristic of the light source, and comparing the initial I-V characteristic to the actual I-V characteristic since changes in the I-V characteristics indicate aging. Actual I-V characteristics can be compared between light sources when they age at different rates to determine light source aging. Moreover, the method may include updating the memory device with the actual I-V characteristic at predetermined times.

Claims

1. A monitoring system comprising:

a sensor having a light source; and

an age detector circuit in communication with said light source and configured to determine an age of said light source based on a current-voltage characteristic of said light source.

2. A monitoring system as set forth in claim 1, wherein said age detector circuit is configured to compare an initial current-voltage characteristic of said light source to an actual current-voltage characteristic of said light source measured to determine the age of said light source.

3. A monitoring system as set forth in claim 2, wherein said age detector circuit includes a memory device and wherein said memory device is configured to store the initial current-voltage characteristic of said light source.

4. A monitoring system as set forth in claim 3, wherein said age detector circuit is configured to update said memory device with the actual current-voltage characteristic at a predetermined time.

5. A monitoring system as set forth in claim 4, further comprising an interference detection circuit in communication with said memory device and said age detector circuit and configured to measure interference caused by an external source of electromagnetic energy.

6. A monitoring system as set forth in claim 5, wherein said interference detection circuit is configured to allow said age detector circuit to communicate with said memory device based on the interference measured.

7. A monitoring system as set forth in claim 6, wherein said interference detection circuit is configured to allow said age detector circuit to communicate with said memory device when no substantial RF interference is measured.

8. A monitoring system as set forth in claim 6, wherein said interference detection circuit is configured to allow said age detector circuit to communicate with said memory device when substantially no light is emitted from said light source.

9. A monitoring system as set forth in claim 6, wherein said memory device is configured to measure ambient light when substantially no light is being emitted from said light source and wherein communication between said age detector circuit and said memory device is limited to times when substantially no ambient light measurements are taking place.

10. A monitoring system as set forth in claim 2, wherein said detector circuit includes a voltage detector circuit in communication with said light source and wherein said voltage detector circuit is configured to measure the actual current-voltage characteristics of said light source.

11. A monitoring system as set forth in claim 10, wherein said voltage detector circuit is configured to detect a forward voltage of said light source.

12. A method of determining an age of a light source, said method comprising:

measuring an initial current-voltage characteristic of the light source;

measuring an actual current-voltage characteristic of the light source; and

comparing the initial current-voltage characteristic of the light source to the actual current-voltage characteristic of the light source to determine the age of the light source.

13. A method as set forth in claim 12, further comprising storing the initial current-voltage characteristic of the light source in a memory device.

14. A method as set forth in claim 13, further comprising accessing the memory device to retrieve the initial current-voltage characteristic of the light source.

15. A method as set forth in claim 13, further comprising updating the memory device with the actual current-voltage characteristics at a predetermined time.

16. A method as set forth in claim 15, further comprising measuring interference caused by an external source or the light source.

17. A method as set forth in claim 16, further comprising updating the memory device when substantially no RF interference is measured.

18. A method as set forth in claim 16, further comprising updating the memory device when substantially no light is emitted from said light source.

19. A method as set forth in claim 16, further comprising updating the memory device when no forward voltage passing through the light source is measured.

20. A method as set forth in claim 12, wherein measuring the initial current-voltage characteristic of the light source includes measuring an initial forward voltage of the light source.

21. A method as set forth in claim 20, wherein measuring the actual current-voltage characteristic of the light source includes measuring an actual forward voltage of the light source.

22. A method as set forth in claim 21, wherein comparing the initial current-voltage characteristic of the light source to the actual current-voltage characteristic of the light source includes comparing the initial forward voltage of the light source to the actual forward voltage of the light source to determine the age of the light source.

23. A method as set forth in claim 12, wherein comparing the actual current-voltage characteristic of one light source and the actual current-voltage characteristic of another light source includes comparing one light source to another to determine the age of the light sources.