WEARABLE HEART RATE MONITOR

• US 20140288436A1
• Filed: 06/03/2014
• Published: 09/25/2014
• Est. Priority Date: 06/22/2012
• Status: Active Grant

• Current Assignee: Fitbit, Inc. (Alphabet Inc.)
• Original Assignee: Fitbit, Inc. (Alphabet Inc.)
• Inventors: Yuen, Shelten Gee Jao, Venkatraman, Subramaniam
• Granted Patent: US 9,456,787 B2
• Time in Patent Office: Days
• US Class Current: 600/479
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence

Abstract

A biometric monitoring device is used to determine a user'"'"'s heart rate by using a heartbeat waveform sensor and a motion detecting sensor. In some embodiments, the device collects collecting concurrent output data from the heartbeat waveform sensor and output data from the motion detecting sensor, detects a periodic component of the output data from the motion detecting sensor, and uses the periodic component of the output data from the motion detecting sensor to remove a corresponding periodic component from the output data from the heartbeat waveform sensor. From this result, the device may determine and present the user'"'"'s heart rate.

Claims

1. A method of determining a user'"'"'s heart rate using a worn biometric monitoring device comprising a plurality of sensors including a heartbeat waveform sensor and a motion detecting sensor, the method comprising:

(a) collecting concurrent output data from the heartbeat waveform sensor and output data from the motion detecting sensor, wherein the output data from the heartbeat waveform sensor provides information about the user'"'"'s heart rate and wherein the output data from the motion detecting sensor provides information about the user'"'"'s periodic physical movements other than heartbeats;

(b) determining a periodic component of the output data from the motion detecting sensor;

(c) processing the output data from the heartbeat waveform sensor to remove the periodic component from the output data from the heartbeat waveform sensor;

(d) using the output data from the motion detecting sensor, determining a range of expected heart rates;

(e) determining the user'"'"'s heart rate from the output data produced in (c), wherein the determined heart rate exists within the range of expected heart rates; and

(f) presenting the user'"'"'s heart rate.

2. The method of claim 1, wherein determining the range of expected heart rates comprises:

(i) determining the user'"'"'s heart rate when the output data from the motion detecting sensor indicates that the user is substantially stationary;

(ii) determining the user'"'"'s activity level and/or activity type from the periodic component of the output data from the motion detecting sensor; and

(iii) determining the range of expected heart rates from the user'"'"'s heart rate determined in (i) and the user'"'"'s activity level and/or activity type determined in (ii).

3. The method of claim 2, wherein a minimum expected heart rate in the range of expected heart rates is greater than the user'"'"'s heart rate determined in (i).

4. The method of claim 2, wherein determining the user'"'"'s activity type comprises inferring the activity type from information contained in the output data from the motion detecting sensor or detecting a manually entered selection of activity type.

5. The method of claim 1, wherein determining the range of expected heart rates comprises determining the user'"'"'s step rate from the output data from the motion detecting sensor.

6. The method of claim 1, wherein determining the user'"'"'s heart rate comprises calculating the spectral density of the output data produced in (c).

7. The method of claim 1, wherein the periodic movement detected by the motion sensor is a wearer'"'"'s limb movements.

8. The method of claim 1, wherein the motion detecting sensor is an accelerometer or a gyroscope.

9. The method of claim 1, wherein the heartbeat waveform sensor comprises a photoplethysmography sensor or an ECG sensor.

10. The method of claim 1, wherein collecting the output data from the heartbeat waveform sensor comprises:

pulsing a light source in the worn biometric monitoring device at a first frequency; and

detecting light from the light source at the first frequency.

11. The method of claim 10, wherein pulsing the light source at the first frequency comprises emitting a succession of light pulses of substantially constant intensity.

12. The method of claim 1, wherein presenting the user'"'"'s heart rate comprises presenting the heart rate on the worn biometric monitoring device.

13. The method of claim 1, wherein presenting the user'"'"'s heart rate comprises presenting the heart rate on an external device that periodically communicates with the worn biometric monitoring device.

14. A wearable fitness monitoring device comprising:

a motion sensor configured to provide output corresponding to motion by a user wearing the fitness monitoring device;

a heartbeat waveform sensor; and

control logic comprising instructions for;

(a) collecting concurrent output data from the heartbeat waveform sensor and output data from the motion detecting sensor, wherein the output data from the heartbeat waveform sensor provides information about the user'"'"'s heart rate and wherein the output data from the motion detecting sensor provides information about the user'"'"'s periodic physical movements other than heartbeats;

(b) determining a periodic component of the output data from the motion detecting sensor;

(c) processing the output data from the heartbeat waveform sensor to remove the periodic component from the output data from the heartbeat waveform sensor;

(d) using the output data from the motion detecting sensor, determining a range of expected heart rates;

(e) determining the user'"'"'s heart rate from the output data produced in (c), wherein the determined heart rate exists within the range of expected heart rates; and

(f) presenting the user'"'"'s heart rate.

15. The wearable fitness monitoring device of claim 14, wherein the heartbeat waveform sensor is a photoplethysmographic sensor comprising (i) a periodic light source, (ii) a photo detector positioned to receive periodic light emitted by the light source after interacting with the user'"'"'s skin, and (iii) circuitry determining the user'"'"'s heart rate from output of the photo detector.

16. The wearable fitness monitoring device of claim 15, wherein the photoplethysmographic sensor comprises two periodic light sources straddling the photo detector.

17. The wearable fitness monitoring device of claim 15, wherein the photoplethysmographic sensor further comprises a housing having a recess in which the photo detector is disposed.

18. The wearable fitness monitoring device of claim 17, wherein the housing of the photoplethysmographic sensor further comprises a second recess in which the periodic light source is disposed.

19. The wearable fitness monitoring device of claim 18, wherein the housing protrudes at least about 1 mm above a base surface of the wearable fitness monitoring device arranged to press against the user'"'"'s skin when worn.

20. The wearable fitness monitoring device of claim 15, wherein the photoplethysmographic sensor further comprises an IML film over the photo detector and the periodic light source.

21. The wearable fitness monitoring device of claim 14, wherein the instructions for determining the range of expected heart rates comprise instructions for:

(i) determining the user'"'"'s heart rate when the output data from the motion detecting sensor indicates that the user is substantially stationary;

(ii) determining the user'"'"'s activity level and/or activity type from the periodic component of the output data from the motion detecting sensor; and

(iii) determining the range of expected heart rates from the user'"'"'s heart rate determined in (i) and the user'"'"'s activity level and/or activity type determined in (ii).

22. The wearable fitness monitoring device of claim 21, wherein a minimum expected heart rate in the range of expected heart rates is greater than the user'"'"'s heart rate determined in (i).

23. The wearable fitness monitoring device of claim 21, wherein the instructions for determining the user'"'"'s activity type comprise instructions for inferring the activity type from information contained in the output data from the motion detecting sensor or detecting a manually entered selection of activity type.

24. The wearable fitness monitoring device of claim 14, wherein the instructions for determining the range of expected heart rates comprise instructions for determining the user'"'"'s step rate from the output data from the motion detecting sensor.

25. The wearable fitness monitoring device of claim 14, wherein the instructions for determining the user'"'"'s heart rate comprise the instructions for calculating the spectral density of the output data produced in (c).

26. The wearable fitness monitoring device of claim 14, wherein the motion detecting sensor is an accelerometer or a gyroscope.

27. The wearable fitness monitoring device of claim 14, wherein the instructions for collecting the output data from the heartbeat waveform sensor comprise instructions for:

pulsing a light source in the wearable biometric monitoring device at a first frequency; and

detecting light from the light source at the first frequency.

28. The wearable fitness monitoring device of claim 27, wherein the instructions for pulsing the light source at the first frequency comprise the instructions for emitting a succession of light pulses of substantially constant intensity.

29. The wearable fitness monitoring device of claim 14, wherein the instructions for presenting the user'"'"'s heart rate comprise instructions for presenting the heart rate on the wearable biometric monitoring device.

30. The wearable fitness monitoring device of claim 14, wherein the instructions for presenting the user'"'"'s heart rate comprise instructions for presenting the heart rate on an external device that periodically communicates with the wearable biometric monitoring device.