BEAT DETECTION DEVICE AND BEAT DETECTION METHOD

• US 20100198087A1
• Filed: 01/08/2010
• Published: 08/05/2010
• Est. Priority Date: 02/02/2009
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: TAKAHASHI, Yusuke, URANO, Osamu, KURODA, Masao
• Granted Patent: US 8,758,258 B2
• Time in Patent Office: Days
• US Class Current: 600/500
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured

Abstract

A beat detection device includes: a pulse wave sensor adapted to detect and output a pulse wave signal; a body motion sensor adapted to detect and output a body motion signal due to a body motion of a human body; a pulse wave signal filtering section adapted to generate an adaptive filter based on the body motion signal to extract a noise signal in the pulse wave signal, and to output a beat signal obtained by eliminating the noise signal from the pulse wave signal; and a filter coefficient setting section adapted to set a coefficient of the adaptive filter to be a predetermined value in response to detection of increase in a body motion change beyond a predetermined threshold value based on the body motion signal.

Claims

1. A beat detection device comprising:

a pulse wave sensor adapted to detect and output a pulse wave signal;

a body motion sensor adapted to detect and output a body motion signal due to a body motion of a human body;

a pulse wave signal filtering section adapted to generate an adaptive filter based on the body motion signal to extract a noise signal in the pulse wave signal, and to output a beat signal obtained by eliminating the noise signal from the pulse wave signal; and

a filter coefficient setting section adapted to set a coefficient of the adaptive filter to be a predetermined value in response to detection of increase in a body motion change beyond a predetermined threshold value based on the body motion signal.

2. The beat detection device according to claim 1, wherein

the filter coefficient setting section resets the coefficient of the adaptive filter to be an initial value.

3. The beat detection device according to claim 1, further comprising:

a body motion storage section adapted to store the body motion signal, which is detected before and after a predetermined body motion change, in correspondence with the coefficient of the adaptive filter,

wherein the filter coefficient setting section sets, in response to detection of increase in the body motion change beyond the predetermined threshold value, and the body motion change corresponding to the predetermined body motion change, the coefficient of the adaptive filter to be a value corresponding to the body motion change.

4. The beat detection device according to claim 1, wherein

the body motion sensor individually outputs body motion signals based on body motions in at least two axial directions, respectively, and

the pulse wave signal filtering section sets the beat signal, which is based on a first pulse wave signal output by the pulse wave sensor and a body motion signal in an axial direction having a most significant influence on the first pulse wave signal, as a second pulse wave signal, and outputs the beat signal based on the second pulse wave signal and a body motion signal having a second most significant influence.

5. The beat detection device according to claim 4, wherein

the beat detection device is used in a state of being attached to an arm, and

the body motion sensor sets a direction from a wrist toward an elbow as the axial direction having the most significant influence, and when extending the arm in parallel to a ground and setting a palm connected to the arm to be parallel to the ground, sets a direction perpendicular to both of the direction from the wrist toward the elbow and the ground as the axial direction having the second most significant influence.

6. The beat detection device according to claim 1, wherein

the filter coefficient setting section detects the increase in the body motion change beyond the predetermined threshold value based on a signal obtained by applying a band-pass filter on the body motion signal.

7. The beat detection device according to claim 1, wherein

the filter coefficient setting section detects the increase in the body motion change beyond the predetermined threshold value based on a summed value of the body motion signal output in a past predetermined period.

8. The beat detection device according to claim 1, wherein

the filter coefficient setting section detects the increase in the body motion change beyond the predetermined threshold value based on an amplitude of the body motion signal output in a past predetermined period.

9. The beat detection device according to claim 1, wherein

the filter coefficient setting section stops, when setting the coefficient of the adaptive filter, setting the coefficient of the adaptive filter until a predetermined period of time elapses.

10. The beat detection device according to claim 1, further comprising:

a pulse measurement section adapted to measure a pulse rate based on the beat signal; and

a display section adapted to display the pulse rate.

11. A beat detection method comprising:

providing a computer adapted to detect a beat signal and provided with a pulse wave sensor adapted to detect a pulse wave signal, and a body motion sensor adapted to detect and output a body motion signal due to a body motion of a human body;

generating an adaptive filter based on the body motion signal to extract a noise signal in the pulse wave signal, and outputting a beat signal obtained by eliminating the noise signal from the pulse wave signal; and

setting a coefficient of the adaptive filter to be a predetermined value in response to detection of increase in a body motion change beyond a predetermined threshold value based on the body motion signal.