Pulse detection apparatus and pulse detection method

• US 10,107,885 B2
• Filed: 11/19/2013
• Issued: 10/23/2018
• Est. Priority Date: 11/20/2012
• Status: Active Grant

• Current Assignee: Kyushu Institute of Technology
• Original Assignee: Kyushu Institute of Technology
• Inventors: Sato, Yasushi
• Primary Examiner(s): Koval, Melissa
• Assistant Examiner(s): Monsur, Nasima
• Application Number:
  US14/439,474
• Publication Number:
  US 20150346306A1
• Time in Patent Office: 1,799 Days
• Field of Search: None
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/6891 Furniture
• CPC Class Codes: A61B 5/6893 Cars
• CPC Class Codes: G01R 33/34092 RF coils specially adapted for NMR spectrometers
• CPC Class Codes: G01R 33/341 comprising surface coils
• CPC Class Codes: G01R 33/3607 RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal
• CPC Class Codes: G01R 33/5635 Angiography, e.g. contrast-enhanced angiography [CE-MRA] or time-of-flight angiography [TOF-MRA]
• CPC Class Codes: G01R 33/60 using electron paramagnetic resonance G01R33/24, G01R33/62 take precedence

Abstract

Provided is a pulse detection apparatus and a pulse detection method less susceptible to movement of a subject and less susceptible to noise. An oscillation frequency controller is configured to cause a frequency variable oscillator to oscillate at a predetermined oscillation frequency, which is a frequency within a range assumed as a resonance frequency of a molecule of a predetermined constituent constituting the blood flowing through a human body. The oscillation frequency controller also controls an oscillation frequency based on a phase difference signal and an amplitude signal, wherein the phase difference signal indicates the phase difference between a transmission signal transmitted from an antenna to the human body and a reception signal received by the antenna, and the amplitude signal indicates the magnitude of the amplitude of the received signal. A pulse detector detects the change of the amplitude signal in an amplitude direction as a pulse signal.

Claims

1. A pulse detection apparatus, comprising:

a magnetic-field application unit to be arranged near a human body to apply a predetermined magnetic field to the human body;

a frequency variable oscillator configured to oscillate at a predetermined oscillation frequency, the predetermined oscillation frequency being a frequency within a range assumed as a resonance frequency of a molecule of a predetermined constituent constituting the blood flowing through the human body;

an antenna arranged near the human body and configured to transmit a signal oscillated by the frequency variable oscillator, as a radio wave, and receive a radio wave reflected by the human body and then returned to the antenna;

a signal separator configured to separate a transmission signal from a reception signal, the transmission signal being transmitted from the antenna, the reception signal being received by the antenna;

a phase comparator configured to compare the phase of the transmission signal with the phase of the reception signal and output a phase difference signal;

an amplitude detector configured to detect the amplitude of the reception signal and output an amplitude signal related to a pulse of the human body;

an oscillation frequency controller configured to control the oscillation frequency of the frequency variable oscillator based on the phase difference signal and the amplitude signal; and

a pulse detector configured to calculate the pulse of the human body using a change of the amplitude signal in an amplitude direction.

2. The pulse detection apparatus according to claim 1, wherein the pulse detector includes a high pass filter that allows signal(s) with a frequency equal to or higher than a frequency corresponding to the period of the pulse to pass through.

3. The pulse detection apparatus according to claim 1, wherein if the amplitude detector detects an amplitude equal to or greater than a predetermined level and the value of the phase difference signal is zero, the oscillation frequency controller will cause a PLL controller to function to control the oscillation frequency so that the value of the phase difference signal is maintained at zero.

4. The pulse detection apparatus according to claim 3, further comprising:

an adaptive filter configured to pass through, among the signal(s) having passed through the pulse detector, only a signal having a pulse wave frequency, wherein the pulse wave frequency is a frequency identical to the frequency of the pulse.

5. A pulse detection apparatus, comprising:

a magnetic-field application unit to be arranged near a human body to apply a predetermined magnetic field to the human body;

a frequency variable oscillator configured to oscillate at a predetermined oscillation frequency, the predetermined oscillation frequency being a frequency within a range assumed as a resonance frequency of a molecule of a predetermined constituent constituting the blood flowing through the human body;

an antenna arranged near the human body and configured to transmit a signal oscillated by the frequency variable oscillator, as a radio wave, and receive a radio wave reflected by the human body and then returned to the antenna;

a signal separator configured to separate a transmission signal from a reception signal, the transmission signal being transmitted from the antenna, the reception signal being received by the antenna;

a phase comparator configured to compare the phase of the transmission signal with the phase of the reception signal and output a phase difference signal;

a first amplitude detector configured to detect the amplitude of the transmission signal and output a first amplitude signal related to a pulse of the human body;

a second amplitude detector configured to detect the amplitude of the reception signal and output a second amplitude signal related to the pulse of the human body;

a transfer function calculator configured to use the first amplitude signal and the second amplitude signal to calculate a transfer function of the antenna;

an oscillation frequency controller configured to control the oscillation frequency of the frequency variable oscillator based on the phase difference signal and the amplitude signal; and

a pulse detector configured to calculate the pulse of the human body using a change of the transfer function calculated by the transfer function calculator in an amplitude direction.

6. The pulse detection apparatus according to claim 5, wherein the transfer function is an S parameter calculated using:

the transmission signal or the reception signal inputted to the signal separator, and a signal outputted from the signal separator or a signal passing through the signal separator.

7. A pulse detection method, comprising:

applying, using a magnetic-field application unit, a predetermined magnetic field to a human body;

causing a frequency variable oscillator to oscillate at a predetermined frequency, the predetermined oscillation frequency being a frequency within a range assumed as a resonance frequency of a molecule of a predetermined constituent constituting the blood flowing through the human body;

transmitting a signal oscillated by the frequency variable oscillator, as a radio wave, from an antenna arranged near the human body, and receiving a radio wave reflected by the human body and then returned to the antenna;

separating, using a signal separator, a transmission signal from a reception signal, the transmission signal being transmitted from the antenna, the reception signal being received by the antenna;

comparing, using a phase comparator, the phase of the transmission signal with the phase of the reception signal and outputting a phase difference signal;

detecting, using an amplitude detector, the amplitude of the reception signal and outputting an amplitude signal related to a pulse of the human body;

controlling, using an oscillation frequency controller, the oscillation frequency of the frequency variable oscillator based on the phase difference signal and the amplitude signal; and

calculate, using a pulse detector, the pulse of the human body using a change of the amplitude signal in an amplitude direction.