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Heart rate and blood oxygen monitoring system

  • US 10,123,711 B2
  • Filed: 01/10/2013
  • Issued: 11/13/2018
  • Est. Priority Date: 01/10/2012
  • Status: Active Grant
First Claim
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1. An electronic device with heart rate monitor comprising:

  • a body including a planar infrared (IR) transmissive surface comprising a plastic or glass;

    a digital processor located within the body;

    a display screen supported by the body;

    an IR light emitting diode (LED) aligned with the IR transmissive surface;

    LED driving circuitry coupled to the IR LED;

    an IR photodetector aligned with the IR transmissive surface, where the IR transmissive surface serves as a window for the IR LED and the IR photodetector such that a finger placed on the IR transmissive surface over the IR LED and the IR photodetector will reflect IR light from the IR LED back to the IR photodetector through the window;

    a filtering and amplification stage having an input coupled to the IR photodetector;

    an analog-to-digital converter (ADC) having an analog input coupled to an output of the filtering and amplification stage and a digital output; and

    memory coupled to the digital processor including code segments executable by the digital processor for;

    (a) continuously determining if a signal has been acquired from the IR detector until a signal has been acquired;

    (b) filtering the acquired signal, determining if it is strong enough for processing and, if not, increasing the IR LED strength and returning to operation (a);

    (c) detecting if a finger has been placed on the IR transmissive surface and, if not, returning to operation (b);

    (d) capturing raw data from the ADC and storing the raw data in a data log;

    (e) checking the data log and, if N seconds of raw data has not been captured, returning to operation (b);

    (f) performing a Fast Fourier Transform (FFT) of the raw data to develop FFT data;

    (g) processing the FFT data for at least one of window, averaging and noise rejection to develop processed FFT data;

    (h) determining a confidence level in the processed FFT data and, if the confidence level is not above a threshold, returning to operation (b);

    (i) calculating a heart rate from the processed FFT data; and

    (j) at least one of displaying and storing the heart rate.

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