OPTICAL HEART RATE SENSOR

• US 20160022160A1
• Filed: 07/23/2015
• Published: 01/28/2016
• Est. Priority Date: 07/23/2014
• Status: Active Grant

• Current Assignee: Shenzhen Goodix Technology Co., Ltd.
• Original Assignee: Goodix Technology Incorporated (Shenzhen Goodix Technology Co., Ltd.)
• Inventors: Pi, Bo, He, Yi
• Granted Patent: US 10,499,821 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0233 Optical standards
• CPC Class Codes: A61B 2560/0247 for compensation or correction of the measured physiological value
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 2562/04 Arrangements of multiple sensors of the same type
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02444 Details of sensor A61B5/02427 takes precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6898 Portable consumer electronic devices, e.g. music players, telephones, tablet computers
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• 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: A61B 5/7228 Signal modulation applied to the input signal sent to patient or subject; demodulation to recover the physiological signal modulation H03C
• CPC Class Codes: A61B 5/7242 using integration

Abstract

Techniques, systems and apparatus are described for implementing a heart rate sensor based on optical measurements of color response of human blood. An optical heart rate sensor can include light source circuitry including a first light emitting diode (LED) to output a first source light signal to a target measurement site, a second LED to output a second source light signal to the target measurement site, a first current pulse driver communicatively coupled to the first LED to modulate the first source light signal output from the first LED at a first predetermined frequency and a second current pulse driver communicatively coupled to the second LED to modulate the second source light signal output from the second LED at a second predetermined frequency different from the first predetermined frequency. The optical heart rate sensor can include detector circuitry including a light detecting photodiode connected to a bias voltage.

Claims

1. An optical heart rate sensor comprising:

light source circuitry comprising;

a light emitting diode (LED) to output a source light signal to a target measurement site, and

a current pulse driver communicatively coupled to the LED to modulate the source light signal output from the LED at a predetermined frequency; and

detector circuitry comprising;

a light detecting photodiode connected to a bias voltage, the light detecting photodiode configured to generate a detector current responsive to detecting a target light signal reflected or scattered from the target measurement site in response to the modulated light signal,

a bank of switches communicatively coupled to the photodiode, and

a capacitor communicatively coupled to the bank of switches;

wherein the bank of switches is configured to switch on and off in response to pulse signals in opposite phases to generate an integrator signal based on charges integrated on the capacitor by the generated detector current.

2. The optical heart rate sensor of claim 1, wherein the bank of switches is configured to switch on and off in response to pulse signals in opposite phases to generate the integrator signal to alternately integrate a charge in the capacitor in opposite directions.

3. The optical heart rate sensor of claim 1, wherein the integrator signal is used to cancel out a background light signal present in the detector current.

4. The optical heart rate sensor of claim 1, wherein the integrator signal can be used to correlate to a heart rate.

5. An optical heart rate sensor comprising:

light source circuitry comprising;

a first light emitting diode (LED) to output a first source light signal to a target measurement site,

a second LED to output a second source light signal to the target measurement site,

a first current pulse driver communicatively coupled to the first LED to modulate the first source light signal output from the first LED at a first predetermined frequency and

a second current pulse driver communicatively coupled to the second LED to modulate the second source light signal output from the second LED at a second predetermined frequency different from the first predetermined frequency; and

detector circuitry comprising;

a light detecting photodiode connected to a bias voltage, the light detecting photodiode configured to generate a detector current responsive to detecting a target light signal reflected or scattered from the target measurement site in response to the modulated light signals,

a bank of switches communicatively coupled to the photodiode, and

a capacitor communicatively coupled to the bank of switches;

wherein the bank of switches is configured to switch on and off in response to pulse signals in opposite phases to allow the generated detector current from the light detecting photodiode to alternately integrate a charge in the capacitor in opposite directions.

6. The optical heart rate sensor of claim 5, wherein the bank of switches is configured to switch on and off in response to pulse signals in opposite phases to generate the integrator signal based to alternately integrating a charge in the capacitor in opposite directions.

7. The optical heart rate sensor of claim 5, wherein the integrator signal is used to cancel out a background light signal present in the detector current.

8. The optical heart rate sensor of claim 5, wherein the modulated light signals of different frequencies are subtracted to compensate for motion artifacts.

9. The optical heart rate sensor of claim 5, wherein the integrator signal can be used to correlate to a heart rate.

10. A method of optically sensing a heart rate, the method comprising:

emitting, from a light source, a source light signal to a target measurement site;

modulating, by a current pulse driver communicatively coupled to the light source, the source light signal emitted from the light source at a predetermined frequency;

generating, from a light detecting photodiode, a detector current responsive to detecting a target light signal reflected or scattered from the target measurement site in response to the modulated light signal; and

generating an integrator signal based on the generated detector current.

11. The method of claim 10, wherein the generating the integrator signal includes switching on and off a bank of switches communicatively coupled to a capacitor in response to pulse signals in opposite phases.

12. The method of claim 10, wherein switching on and off the bank of switches in response to the pulse signals in opposite phases to generate the integrator signal includes alternately integrating a charge in the capacitor in opposite directions.

13. The method of claim 10, wherein the integrator signal is used to cancel out a background light signal present in the detector current.

14. The method of claim 10, wherein the integrator signal can be used to correlate to a heart rate.

15. The method of claim 10, comprising:

emitting, by another source light, another source light; and

modulating, by another current pulse driver communicatively coupled to the other source light, the other source light signal emitted from the other light source at another predetermined frequency different from the predetermined frequency.

16. The method of claim 15, wherein the generating the detector current includes:

generating, from the light detecting photodiode, the detector current responsive to detecting a target light signal reflected or scattered from the target measurement site in response to the modulated light signal and the other modulated light signal; and

generating an integrator signal based on the generated detector current.

17. The method of claim 16, wherein the modulated light signals of different frequencies are subtracted to compensate for motion artifacts.

18. An optical heart rate sensor comprising:

light emitting means for emitting a source light signal to a target measurement site;

signal modulating means for modulating emitted the source light signal emitted from the light emitting means at a predetermined frequency; and

light detector means for generating a detector current responsive to detecting a target light signal reflected or scattered from the target measurement site in response to the modulated light signal; and

switching means for turning on and off electrical connection to a capacitor to allow the capacitor to accumulate charges.

19. The optical heart rate sensor of claim 18, wherein the switching means is configured to switch on and off the electrical connection to the capacitor in response to pulse signals in opposite phases to generate an integrator signal to alternately integrate a charge in the capacitor in opposite directions.

20. The optical heart rate sensor of claim 19, wherein the integrator signal can be used to correlate to a heart rate.