Heart rate data collection

• US 9,282,902 B2
• Filed: 04/22/2015
• Issued: 03/15/2016
• Est. Priority Date: 06/22/2012
• Status: Active Grant

• Current Assignee: Fitbit, Inc. (Alphabet Inc.)
• Original Assignee: Fitbit, Inc. (Alphabet Inc.)
• Inventors: Richards, Peter W., Elliot, Thomas Samuel, Yuen, Shelten Gee Jao
• Primary Examiner(s): Lamprecht, Joel
• Application Number:
  US14/693,710
• Publication Number:
  US 20150223708A1
• Time in Patent Office: 328 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/185 Optical shielding, e.g. baffles
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• 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 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• 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 5/02427 Details of sensor
• CPC Class Codes: A61B 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• 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 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: A61B 5/4815 Sleep quality
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7225 : Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: H04L 67/12 : specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04W 4/027 : using movement velocity, acceleration information
• CPC Class Codes: H04W 4/80 : Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

One innovative aspect is directed to heartrate data collection. In some implementations, a circuit includes a light detector for generating a detected signal based on received light. The circuit includes a switching circuit configured to receive a first signal based on the detected signal and to switch among a first and a second configuration. In some implementations, the circuit includes a first and a second sampling circuit for sampling a value of the first signal when the switching circuit is in the first configuration and second configurations, respectively. In some implementations, the circuit includes an ambient light cancellation circuit for countering a first component of the first signal while the first switching circuit is in the first configuration. In some implementations, the circuit includes an adjustable gain circuit for adjusting a gain of the first signal while the first switching circuit is in the first configuration.

Claims

1. A circuit comprising:

a light detector for receiving light and for generating a first electrical signal based on the received light;

a controller for generating one or more first control signals and one or more second control signals;

a first switching circuit having at least a first configuration and a second configuration, the first switching circuit for;

receiving a second electrical signal based on the first electrical signal,

receiving the one or more first control signals, and

switching among at least the first configuration and the second configuration based on the one or more first control signals;

a first sampling circuit for sampling a value of the second electrical signal while the first switching circuit is in the first configuration; and

an ambient light cancellation circuit for generating a third electrical signal to at least partially counter a first component of the first electrical signal, the third electrical signal being based on the one or more second control signals and a value of the second electrical signal sampled by the first sampling circuit.

2. The circuit of claim 1, wherein the ambient light cancellation circuit includes an adjustable impedance stage between a first terminal of the ambient light cancellation circuit and a second terminal of the ambient light cancellation circuit for providing an adjustable impedance to adjust the third electrical signal based on the one or more second control signals.

3. The circuit of claim 2, wherein:

the adjustable impedance stage includes an impedance network having at least a first impedance path having a first impedance, and a second impedance path having a second impedance; and

the ambient light cancellation circuit further includes a second switching circuit for switching among at least the first impedance path and the second impedance path based on the one or more second control signals.

4. The circuit of claim 1, further including a second sampling circuit for sampling a value of the second electrical signal while the first switching circuit is in the second configuration.

5. The circuit of claim 4, further including an analog-to-digital converter (ADC) for generating a digital voltage signal based on the second electrical signal sampled by the second sampling circuit.

6. A device comprising:

the circuit of claim 5; and

a light emitter for emitting light toward a region of the skin of a user.

7. The device of claim 6, further including a driver circuit that powers the light emitter based on one or more third control signals generated by the controller, wherein the third control signals cause the driver circuit to drive the light emitter during an interval of time while the first switching circuit is in the second configuration, and wherein the third control signals cause the driver circuit to turn off the light emitter after the second sampling circuit has sampled the second electrical signal and prior to the first switching circuit switching into the first configuration.

8. The device of claim 6, wherein the light emitter and the circuit are arranged at least partially within a housing wearable by the user.

9. A circuit comprising:

a light detector for receiving light and for generating a first electrical signal based on the received light;

a controller for generating one or more first control signals and one or more second control signals;

a first switching circuit having at least a first configuration and a second configuration, the first switching circuit for;

receiving a second electrical signal based on the first electrical signal,

receiving the one or more first control signals, and

switching among at least the first configuration and the second configuration based on the one or more first control signals;

an adjustable gain circuit for adjusting a third electrical signal to adjust a gain of the second electrical signal relative to the first electrical signal while the first switching circuit is in the first configuration, the third electrical signal being based on the first electrical signal and the one or more second control signals; and

a first sampling circuit for sampling a value of the second electrical signal while the first switching circuit is in the first configuration.

10. The circuit of claim 9, further including an analog-to-digital converter (ADC) for generating a digital voltage signal based on the second electrical signal sampled by the first sampling circuit.

11. The circuit of claim 10, wherein the digital voltage signal is representative of a heartrate of a user.

12. The circuit of claim 9, wherein the adjustable gain circuit includes:

a first terminal;

a second terminal; and

an adjustable impedance stage between the first terminal and the second terminal for providing an adjustable impedance to adjust the third electrical signal based on the one or more third control signals.

13. The circuit of claim 12, wherein:

the adjustable impedance stage includes an impedance network having at least a first impedance path having a first impedance, and a second impedance path having a second impedance; and

the adjustable gain circuit further includes a second switching circuit for switching among at least the first impedance path and the second impedance path based on the one or more second control signals.

14. The circuit of claim 9, further including a second sampling circuit for sampling a value of the second electrical signal while the first switching circuit is in the second configuration.

15. The circuit of claim 14, further including an ambient light cancellation circuit for generating a fourth electrical signal to at least partially counter a first component of the first electrical signal while the first switching circuit is in the first configuration, the fourth electrical signal being based on one or more third control signals and the value of the second electrical signal sampled by the second sampling circuit.

16. The circuit of claim 15, wherein the ambient light cancellation circuit includes an adjustable impedance stage between a first terminal of the ambient light cancellation circuit and a second terminal of the ambient light cancellation circuit for providing an adjustable impedance to adjust the fourth electrical signal based on the one or more second control signals.

17. The circuit of claim 16, wherein:

the adjustable impedance stage includes an impedance network having at least a first impedance path having a first impedance, and a second impedance path having a second impedance; and

the ambient light cancellation circuit further includes a second switching circuit for switching among at least the first impedance path and the second impedance path based on the one or more third control signals.

18. The circuit of claim 9, wherein:

the first electrical signal is a current signal;

the second electrical signal is a voltage signal; and

the circuit further includes an electrical current-to-voltage converter for converting the first electrical signal to the second electrical signal.

19. A device comprising:

the circuit of claim 9; and

a light emitter for emitting light toward a region of the skin of a user.

20. The device of claim 19, further including a driver circuit that powers the light emitter based on one or more third control signals generated by the controller, wherein the third control signals cause the driver circuit to drive the light emitter during an interval of time while the first switching circuit is in the first configuration, and wherein the third control signals cause the driver circuit to turn off the light emitter after the first sampling circuit has sampled the second electrical signal and prior to the first switching circuit switching into the second configuration.

21. The device of claim 19, wherein the light emitter and the circuit are arranged at least partially within a housing wearable by the user.

22. A method comprising:

causing, by a controller, a switching circuit to transition from a first configuration to a second configuration to enable a first sampling circuit;

detecting, by a light detector, an ambient light signal;

generating, by the light detector, a first detected signal based on the ambient light signal;

sampling, by the first sampling circuit, the first detected signal;

emitting, by a light emitter, an emitted light signal;

causing, by the controller, the switching circuit to transition from the second configuration to the first configuration to enable a second sampling circuit;

detecting, by the light detector, an incident light signal including an emitted component from the emitted light signal and an ambient component from the ambient light signal;

generating, by the light detector, a second detected signal based on the incident light signal;

generating, by an ambient light cancellation circuit, a countering signal based on the sampled first detected signal, the countering signal for countering at least a portion of an ambient component of the second detected signal;

sampling, by the second sampling circuit, the second detected signal while the ambient component of the second detected signal is being countered; and

providing an output signal based on the sampled second detected signal.

23. The method of claim 22, further including:

performing the method of claim 22 over a plurality of cycles; and

digitizing, by an analog-to-digital converter, the provided output signals to provide a digital voltage signal.

24. The method of claim 23, wherein the digital voltage signal is representative of a heartrate of a user.

25. The method of claim 22, further including generating at least one physiological metric based on the output signal.

26. The method of claim 22, further including:

setting, by the controller, an impedance of an adjustable gain circuit; and

providing, by the adjustable gain circuit, a gain adjustment signal based on the set impedance for adjusting a gain of the second detected signal.

27. A method comprising:

emitting, by a light emitter, an emitted light signal;

setting, by a controller, an impedance of an adjustable gain circuit;

causing, by the controller, a switching circuit to transition from a first configuration to a second configuration to enable a first sampling circuit;

detecting, by the light detector, an incident light signal including an emitted component from the emitted light signal;

generating, by the light detector, a first detected signal based on the incident light signal;

providing, by the adjustable gain circuit, a gain adjustment signal based on the set impedance for adjusting a gain of the first detected signal while the first switching circuit is in the second configuration;

sampling, by the first sampling circuit, the first detected signal while the first switching circuit is in the second configuration and while the gain of the first detected signal is adjusted by the gain adjustment signal; and

providing an output signal based on the sampled first detected signal.

28. The method of claim 27, further including:

performing the method of claim 27 over a plurality of cycles; and

digitizing, by an analog-to-digital converter, the provided output signals to provide a digital voltage signal.

29. The method of claim 28, wherein the digital voltage signal is representative of a heartrate of a user.

30. The method of claim 27, further including generating at least one physiological metric based on the output signal.