Methods, Systems and Devices for Measuring Fingertip Heart Rate

• US 20150173628A1
• Filed: 03/05/2015
• Published: 06/25/2015
• Est. Priority Date: 01/15/2013
• Status: Abandoned Application

• Current Assignee: Fitbit, Inc. (Alphabet Inc.)
• Original Assignee: Fitbit, Inc. (Alphabet Inc.)
• Inventors: Yuen, Shelten, Venkatraman, Subramaniam, Albert, Eric Van, Park, James
• Application Number:
  US14/639,409
• Publication Number:
  US 20150173628A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2503/10 Athletes
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0082 adapted for particular medical purposes
• 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 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/1112 Global tracking of patients, e.g. by using GPS
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• 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 5/7271 Specific aspects of physiological measurement analysis A61B5/316, A61B5/349 and A61B5/374 take precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A system and method of tracking activity includes a motion sensor, a light source and a light detector. The light detector is configured to capture an amount of the light that is reflected back to the light detector, at least a first portion of the light reflected back to the light detector is reflected from a blood vessel disposed under a skin of a user when the user places the skin over the heart rate monitor location on the housing. A processor is in communication with the motion sensor and the light detector and can process the reflected light to identify heart beats of the user and produce an indication of a heart rate. The indication of the heart rate can be displayed on the display screen as an option, in addition to the metrics that quantify the motion data.

Claims

1. A method of tracking activity, comprising,

sensing motion with a motion sensor, the motion sensor including a processor, the processor configured for processing motion data produced by the motion sensor;

displaying metrics that quantify the motion data produced by the motion sensing, the metrics being displayed on a device display screen integrated with a housing of the motion sensor;

directing light emitted from a light source, the light source being included in the housing at a heart rate monitor location on the housing; and

capturing an amount of the light that is reflected back to a light detector, the light detector integrated within the housing, at least a first portion of the light reflected back to the light detector is reflected from a blood vessel disposed under a skin of a user when the user places the skin over the heart rate monitor location on the housing, the processor further being in communication with the light detector to enable processing of the reflected light, the processing configured to identify heart beats of the user and produce an indication of a heart rate, the indication of the heart rate being displayable on the display screen as an option, in addition to the metrics that quantify the motion data, wherein identifying heart beats includes measuring a baseline reflectance signal of the light reflected from the blood vessel between each one of the heart beats and for detecting a second reflectance signal corresponding to at least one heart beat in the blood vessel, the second reflectance signal being less than the baseline reflectance signal, where the blood vessel scatters more of the light during the at least one heart beat than between each one of the heart beats.

2. The method of claim 1, wherein identifying heart beats includes identifying and filtering at least one falsely detected heart beat coinciding with motion detected by the motion sensor.

3. The method of claim 1, wherein the heart rate is calculated including:

detecting the plurality of heart beats in the light received in the light detector within a sampling time period;

measuring a first time interval between a first beat of the detected plurality of heart beats and a second beat of the detected plurality of heart beats;

dividing the sample time interval by the first time interval to determine a first estimate of heart beats detected within the sampling time period;

extrapolating the first estimate of heart beats within the sampling time period to a first estimated heart beats per minute; and

outputting the first estimate heart beats per minute to the display screen.

4. The method of claim 3, wherein calculating the heart rate further includes:

adding at least one beat to the first estimate of heart beats to produce a second estimate of heart beats;

subtracting at least one beat from the first estimate of beats to produce a third estimate of heart beats;

scoring the first estimate of heart beats, the second estimate of heart beats and the third estimate of heart beats;

selecting a highest scoring of the first estimate of heart beats, the second estimate of heart beats and the third estimate of heart beats; and

outputting the selected estimated heart beats per minute to the display screen.

5. The method of claim 1, wherein the heart rate is calculated including:

detecting the plurality of heart beats in the light received in the light detector within a sampling time period;

estimating a first estimated heart beats per minute corresponding to the plurality of heart beats detected in the sampling time period;

estimating a second estimated heart beats per minute, wherein the second estimated heart beats per minute is greater than the first estimated heart beats per minute;

estimating a third estimated heart beats per minute, wherein the third estimated heart beats per minute is less than first estimated heart beats per minute;

scoring the first estimate of heart beats, the second estimate of heart beats and the third estimate of heart beats;

selecting a highest scoring of the first estimate of heart beats, the second estimate of heart beats and the third estimate of heart beats; and

outputting the selected estimated heart beats per minute to the display screen.

6. The method of claim 5, wherein the second estimated heart beats per minute includes at least one heart beat more than the plurality of heart beats in the light received in the light detector within a sampling time period and the third estimated heart beats per minute includes at least one heart beat less than the plurality of heart beats in the light received in the light detector within a sampling time period.

7. The method of claim 1, further comprising,

detecting a pressure applied to the heart rate monitor location of the housing with the skin of the user during the identification of heart beats, the pressure being detected by a pressure detecting system included in the housing;

and

outputting a feedback signal regarding the detected pressure applied to the heart rate monitor location, the feedback indication being indicative of more or less pressure desired to produce the heart rate.

8. The method of claim 7, wherein detecting the pressure includes at least one of a group consisting of:

processing the reflected light, the processing configured to identify one of an excess pressure, an insufficient pressure or an acceptable pressure from the detected heart beats of the user;

or

detecting a pressure with a pressure sensor disposed near light source and the light detector.

9. The method of claim 1, further comprising, displaying one or both of waveform data or numerical data when the skin of the user is over the heart rate monitor location and the heart beats are being identified over a sampling time period;

and

displaying the heart rate on the display screen upon concluding the sampling time period.

10. The method of claim 9, further comprising, displaying at least one recalled heart rate to be displayed on the display screen.

11. The method of claim 1, wherein the processing configured to identify heart beats of the user and produce an indication of a heart rate includes identifying and filtering a falsely detected heart beat coinciding with motion detected by the motion sensor.

12. The method of claim 1, further comprising, detecting an infrared (IR) proximity with at least one infrared (IR) proximity sensor associated with the light source and light detector, the IR proximity sensor configured to activate the light source and light detector upon detecting presence of the skin of the user, wherein detecting presence of the skin of the user further functions to navigate to one or more metrics of the display screen.

13. The method of claim 1, wherein the light detector is disposed next to the light source.

14. The method of claim 1, wherein the heart rate monitor location includes a button and the button has an infrared (IR) light transmitting structure, the light source and the light detector are disposed substantially below the button.

15. The method of claim 1, further comprising:

Communicating to a computer with a communication transceiver configured for communicating via at least one a wireless network;

an ambient light sensor; and

an indicator for visually identifying the heart rate monitor location on the housing.

16. The method of claim 1, wherein the light source and the reflected light detector can be selected for any suitable wavelength or suitable band of wavelengths of light ranging from between infrared wavelengths through a human visible spectrum to ultraviolet wavelengths.

17. The method of claim 1, wherein the light source includes at least one of:

an infrared (IR) light source, wherein the IR light emitted from the light source produces a deadfront at the heart rate monitor location of the housing;

or

a green light source and the heart rate monitor location includes a translucent green window.

18. The method of claim 1, wherein the housing includes at least one marking to identify a location of the heart rate monitor on the housing.

19. A heart rate monitor comprising:

a light source;

a light detector disposed to receive light emitted from the light source and reflected from a blood vessel disposed within in a heart rate monitor subject;

a display screen; and

a processor coupled to the light source, the light detector and the display screen, the controller including memory and processor including computer executable instructions for;

detecting a plurality of heart beats in the light received in the light detector within a sampling time period including measuring a baseline reflectance signal of the light reflected from the blood vessel between each one of the heart beats and for detecting a second reflectance signal corresponding to at least one heart beat in the blood vessel, the second reflectance signal being less than the baseline reflectance signal, where the blood vessel scatters more of the light during the at least one heart beat than between each one of the heart beats;

estimating a first estimated heart beats per minute corresponding to the plurality of heart beats detected in the sampling time period;

estimating a second estimated heart beats per minute, wherein the second estimated heart beats per minute is greater than the first estimated heart beats per minute;

estimating a third estimated heart beats per minute, wherein the third estimated heart beats per minute is less than first estimated heart beats per minute;

scoring the first estimate of heart beats, the second estimate of heart beats and the third estimate of heart beats;

selecting a highest scoring of the first estimate of heart beats, the second estimate of heart beats and the third estimate of heart beats; and

outputting the selected estimated heart beats per minute to the display screen.

20. An activity tracking device, comprising,

a housing, the housing including:

a motion sensor and a processor, the processor configured for processing motion data produced by the motion sensor;

a display screen integrated with the housing to display metrics that quantify the motion data produced by the motion sensor;

a light source integrated within the housing to enable light to be directed out of the housing at a heart rate monitor location on the housing; and

a light detector integrated within the housing, the light detector configured to capture an amount of the light that is reflected back to the light detector, at least a first portion of the light reflected back to the light detector is reflected from a blood vessel disposed under a skin of a user when the user places the skin over the heart rate monitor location on the housing, the processor further being in communication with the light detector to enable processing of the reflected light, the processing configured to identify heart beats of the user and produce an indication of a heart rate, the indication of the heart rate being displayable on the display screen as an option, in addition to the metrics that quantify the motion data, wherein the heart rate is calculated based on an algorithm that;

calculates a first estimate of heart beats per minute corresponding to detected plurality of heart beats in the light received in the light detector within a sampling time period;

calculates a refined estimate of heart beats per minute; and

identifies and filters at least one falsely detected heart beat coinciding with motion detected by the motion sensor.