PULSE MEASUREMENT DEVICE, PULSE MEASUREMENT METHOD, AND PULSE MEASUREMENT PROGRAM

• US 20150164350A1
• Filed: 02/23/2015
• Published: 06/18/2015
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Inventors: FUJII, Kenji, KAMEGAWA, Shigemi
• Granted Patent: US 9,924,881 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02422 within occluders
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence

Abstract

A pulse wave signal expressing a pulse is obtained by detecting a measurement subject'"'"'s pulse a using a pulse wave sensor. The pulse wave signal is stored in a storage unit. A frequency spectrum of the pulse wave signal is found by converting the time-domain pulse wave signal into the frequency domain. Whether or not the measurement subject is at rest is determined by finding a frequency range, within a predetermined total frequency range the pulse rate of a person can take on, in which an intensity of a frequency component of the frequency spectrum exceeds a first threshold, and finding whether or not a percentage of the total frequency range occupied by the frequency range is less than a second threshold. A pulse rate from the point in time when the measurement subject has been determined to be at rest is found as the measurement subject'"'"'s at-rest pulse rate.

Claims

1. A pulse measurement device comprising:

a data obtainment unit configured to obtain a pulse wave signal expressing a pulse by detecting a pulse of a measurement subject using a pulse wave sensor;

a storage unit configured to store the pulse wave signal;

a frequency conversion unit configured to find a frequency spectrum of the pulse wave signal by converting the time-domain pulse wave signal stored in the storage unit into a frequency domain;

a rest state determination unit configured to determine whether or not the measurement subject is at rest by finding a frequency range, within a predetermined total frequency range the pulse rate of a person can take on, in which an intensity of a frequency component of the frequency spectrum exceeds a first threshold, and finding whether or not a percentage of the total frequency range occupied by the frequency range is less than a second threshold; and

a pulse rate obtainment unit configured to find a pulse rate from the point in time when the measurement subject has been determined to be at rest as the measurement subject'"'"'s at-rest pulse rate.

2. The pulse measurement device according to claim 1,

wherein the pulse wave sensor is a photoelectric sensor including a light-emitting unit configured to emit light toward the measurement area at a given emitted light intensity and a light-receiving unit that receives light reflected by or transmitted through the measurement area.

3. The pulse measurement device according to claim 1,

wherein the pulse rate obtainment unit finds, as the measurement subject'"'"'s at-rest pulse rate, a frequency indicating a maximum intensity peak among the intensity peaks contained in the frequency spectrum when it has been determined that the measurement subject is at rest.

4. The pulse measurement device according to claim 1,

wherein the first threshold is set as a ratio to the intensity of the maximum intensity peak among the intensity peaks contained in the frequency spectrum.

5. The pulse measurement device according to claim 1,

wherein the frequency conversion unit segments the time-domain pulse wave signal stored in the storage unit into periods of a predetermined given length and finds a frequency spectrum of the pulse wave signal by converting the pulse wave signal into the frequency domain cyclically;

and

the rest state determination unit determines whether or not the percentage is less than the second threshold for the frequency spectra of the pulse wave signal found cyclically, and determines that the measurement subject is at rest when the percentage is less than the second threshold a plurality of times in succession.

8. The pulse measurement device according to claim 2,

wherein the pulse rate obtainment unit finds, as the measurement subject'"'"'s at-rest pulse rate, a frequency indicating a maximum intensity peak among the intensity peaks contained in the frequency spectrum when it has been determined that the measurement subject is at rest.

9. The pulse measurement device according to claim 2,

wherein the first threshold is set as a ratio to the intensity of the maximum intensity peak among the intensity peaks contained in the frequency spectrum.

10. The pulse measurement device according to claim 3,

wherein the first threshold is set as a ratio to the intensity of the maximum intensity peak among the intensity peaks contained in the frequency spectrum.

11. The pulse measurement device according to claim 8,

wherein the first threshold is set as a ratio to the intensity of the maximum intensity peak among the intensity peaks contained in the frequency spectrum.

6. A pulse measurement method comprising:

a step of obtaining a pulse wave signal expressing a pulse by detecting a pulse of a measurement subject using a pulse wave sensor and storing the pulse wave signal in a storage unit;

a step of finding a frequency spectrum of the pulse wave signal by converting the time-domain pulse wave signal stored in the storage unit into a frequency domain;

a step of determining whether or not the measurement subject is at rest by finding a frequency range, within a predetermined total frequency range the pulse rate of a person can take on, in which an intensity of a frequency component of the frequency spectrum exceeds a first threshold, and finding whether or not a percentage of the total frequency range occupied by the frequency range is less than a second threshold; and

a step of finding, as the measurement subject'"'"'s at-rest pulse rate, a frequency indicating a maximum intensity peak among the intensity peaks contained in the frequency spectrum when it has been determined that the measurement subject is at rest.

7. A pulse measurement program for causing a computer to execute the pulse measurement method according to claim 6.