Pulsimeter

• US 6,036,653 A
• Filed: 11/05/1997
• Issued: 03/14/2000
• Est. Priority Date: 11/07/1996
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Baba, Norimitsu, Kobayashi, Michio, Kosuda, Tsukasa
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US08/964,966
• Time in Patent Office: 860 Days
• Field of Search: 600/500, 600/501, 600/502, 600/503, 600/518, 600/481, 600/490
• US Class Current: 600/500
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

A pulsimeter analyzes a pulse wave signal output by a pulse wave sensor worn on a part of the body while exercising, enables extraction of only the pulse wave component without being affected by movement of the body, and evaluates a detection state indicative of whether the pulse wave sensor is detecting the pulse. A pulse wave component extractor extracts a pulse wave component from the result of a time-frequency analysis of a pulse wave signal. A pulse rate calculator calculates the pulse rate per minute based on the pulse wave component extracted by the pulse wave component extractor. The pulse rate is then displayed. A detection state of the pulse wave sensor is also displayed by providing a detection state evaluator for determining the presence of a pulse wave component based on the result output by the pulse wave component extractor.

Claims

1. A pulsimeter worn by a user comprising:

a pulse wave detector, said pulse wave detector detects at least one of a pulse wave component and a body movement component and outputs a pulse wave signal;

a time-frequency analyzer, said time-frequency analyzer time-frequency analyzes the pulse wave signal responsive to said pulse wave detector; and

a pulse wave extractor, said pulse wave extractor extracts, independent of any body movement component produced by movement of the user, the pulse wave component responsive to said time-frequency analyzer.

2. The pulsimeter according to claim 1, wherein said time-frequency analyzer time-frequency analysis is in accordance with a parameter of a function, said pulsimeter further comprising a parameter changing means for changing the parameter of the function based on a pulse wave signal obtained from the pulse wave detector when the user is at rest and a movement component is absent.

4. The pulsimeter according to claim 1 or 3, wherein said time-frequency analyzer time-frequency analyzes in accordance with a wavelet transform.

5. The pulsimeter according to claim 1 or 3, wherein said time-frequency analyzer time-frequency analyzes in accordance with a Wigner-Ville distribution.

3. A pulsimeter worn by a user comprising:

a pulse wave detector, said pulse wave detector detects at least one of a pulse component and a body movement component and outputs a pulse wave signal;

a time-frequency analyzer, said time-frequency analyzer time-frequency analyzes the pulse wave signal responsive to said pulse wave detector;

a pulse wave extractor, said pulse wave extractor extracts the pulse wave component responsive to said time-frequency analyzer; and

a detection state evaluator, said detection state evaluator evaluates a pulse wave detection state of said pulse wave detector based on the pulse wave component extracted by said pulse wave extractor.

6. A method of measuring a pulse wave of a user comprising the steps of:

(a) detecting at least one of a pulse wave component representing a pulse measurement of a user and a movement component indicative of any movement by the user;

(b) time-frequency analyzing the at least one detected pulse wave component and movement component;

(c) extracting the pulse wave component from step (b) independent of any of the movement component.

7. A method according to claim 6,

wherein step (b) comprises the step of applying a wavelet transform;

wherein step (c) comprises the steps of

determining any inflection points;

counting a number of inflection points; and

wherein if there is only one inflection point only the pulse wave component is present, and

wherein if there are at least two inflection points the movement component is superimposed on the pulse wave component.

8. A method according to claim 7, wherein one of the at least two inflection points has a frequency furthest away from a previous frequency point is the movement component and another one of the at least two inflection points has a frequency closest to the previous frequency point is the pulse wave component.

9. A method according to claim 7, wherein the wavelet transform is a Symlets function.

10. A method according to claim 7, wherein the wavelet transform is a Daubechies function.

11. A method according to claim 6,

wherein step (b) comprises the step of applying a wavelet transform;

wherein step (c) comprises the steps of

determining any inflection points;

counting a number of inflection points; and

wherein if there is only one inflection point only the pulse wave component is present, and

wherein if there an absence of an inflection point the pulse wave component and the movement component are absent.

12. A method according to claim 11,

wherein if one inflection point is present and a frequency of the one inflection point is within a predetermined amount of a previous frequency then the one inflection point is a pulse wave component, if the one inflection point is present and the frequency of the one inflection point is without the predetermined amount of the previous frequency then the one inflection point is a movement component,

wherein if there are at least two inflection points then the pulse wave component and the movement component are present,

wherein one of the at least two inflection points has a frequency furthest away from a previous frequency point is the movement component and another one of the at least two inflection points has a frequency closest to the previous frequency point is the pulse wave component.

13. A method according to claim 6,

wherein step (b) comprises the step of applying a wavelet transform having a basis function parameter;

wherein step (a) further comprises the step of setting the basis function prior to step (b);

wherein step (c) comprises the steps of

determining any inflection points; and

counting a number of inflection points;

wherein if there is only one inflection point only the pulse wave component is present, and

wherein if there an absence of an inflection point the pulse wave component and the movement component are absent.

14. A pulsimeter worn by a user comprising:

(a) detecting means for detecting at least one of a pulse wave component representing a pulse measurement of a user and a movement component indicative of any movement by the user;

(b) time-frequency analyzing means for time-frequency analyzing the at least one detected pulse wave component and movement component sensed by said detecting means;

(c) extracting means for extracting the pulse wave component from said time-frequency analyzing means independent of any of the movement component.

15. A pulsimeter according to claim 14,

wherein said time-frequency analyzing means for further applying a wavelet transform;

wherein said extracting means for further

determining any inflection points;

counting a number of inflection points; and

wherein if there is only one inflection point only the pulse wave component is present, and

wherein if there are at least two inflection points the movement component is superimposed on the pulse wave component.

16. A pulsimeter according to claim 15, wherein one of the at least two inflection points has a frequency furthest away from a previous frequency point is the movement component and another one of the at least two inflection points has a frequency closest to the previous frequency point is the pulse wave component.

17. A pulsimeter according to claim 15, wherein the wavelet transform is a Symlets function.

18. A pulsimeter according to claim 15, wherein the wavelet transform is a Daubechies function.

19. A pulsimeter according to claim 14,

wherein said time-frequency analyzing means for further applying a wavelet transform;

wherein said extracting means for further

determining any inflection points;

counting a number of inflection points; and

wherein if there is only one inflection point only the pulse wave component is present, and

wherein if there an absence of an inflection point the pulse wave component and the movement component are absent.

20. A pulsimeter according to claim 19,

wherein if one inflection point is present and a frequency of the one inflection point is within a predetermined amount of a previous frequency then the one inflection point is a pulse wave component, if the one inflection point is present and the frequency of the one inflection point is without the predetermined amount of the previous frequency then the one inflection point is a movement component,

wherein if there are at least two inflection points then the pulse wave component and the movement component are present,

wherein one of the at least two inflection points has a frequency furthest away from a previous frequency point is the movement component and another one of the at least two inflection points has a frequency closest to the previous frequency point is the pulse wave component.

21. A pulsimeter according to claim 14,

wherein said time-frequency analyzing means for further applying a wavelet transform having a basis function parameter;

wherein said pulsimeter comprises a parameter changing means for setting the basis function;

wherein said extracting means for further

determining any inflection points;

counting a number of inflection points; and

wherein if there is only one inflection point only the pulse wave component is present, and

wherein if there an absence of an inflection point the pulse wave component and the movement component are absent.