Pulse wave detecting device and method therefor

• US 7,470,235 B2
• Filed: 09/23/2005
• Issued: 12/30/2008
• Est. Priority Date: 03/30/2005
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Suzuki, Takuji, Ouchi, Kazushige, Moriya, Akihisa
• Primary Examiner(s): Marmor, II; Charles A
• Assistant Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US11/233,022
• Publication Number:
  US 20060224054A1
• Time in Patent Office: 1,194 Days
• Field of Search: 600/485, 600500-503
• US Class Current: 600/500
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light

Abstract

A pulse wave measuring apparatus can determine an optimum combination of a pair of light-emitting element and light-receiving element out of plural light-emitting elements and plural light-receiving elements on a real time basis according to a difference of signal intensity of a pulse wave signal from the light-receiving element and always measure an stable pulse wave of a wrist artery robustly.

Claims

1. A measuring apparatus for detecting a pulse wave signal indicating a change in a blood flow in the blood vessel of a patient by using light, comprising:

a sensor module including a plurality of light-emitting elements to irradiate the blood vessel, and a plurality of light-receiving elements to receive reflected light as a pulse wave signal from the blood vessel, each element being configured to be attached on the surface of the patient;

a processor for light emission that causes the plurality of light-emitting elements to emit light one after another;

an autocorrelation value calculating processor that calculates autocorrelation values of respective pulse wave signals corresponding to respective combinations of the light-emitting elements, which have emitted light, and the light-receiving elements, which have received light, respectively; and

an optimum position identifying processor that selects a combination of a light-emitting element and a light-receiving element, which has outputted a pulse wave signal with a highest autocorrelation value among the respective autocorrelation values, as an optimum combination,

wherein the autocorrelation value calculating processor slices waveforms of pulse wave signals in an arbitrary period from the pulse wave signals, respectively, and obtains an autocorrelation between the sliced waveforms and the pulse wave signals to thereby calculate autocorrelation values of the respective pulse wave signals.

2. A pulse wave measuring apparatus according to claim 1, wherein the arbitrary period includes a pulse wave of at least one beat.

3. A measuring apparatus for detecting a pulse wave signal indicating a change in a blood flow in the blood vessel of a patient by using light, comprising

a sensor module including a plurality of light-emitting elements to irradiate the blood vessel, and a plurality of light-receiving elements to receive reflected light as a pulse wave signal from the blood vessel, each element being configured to be attached on a surface of the patient;

a processor for light emission that causes the plurality of light-emitting elements to emit light one after another;

an autocorrelation value calculating processor that calculates autocorrelation values of respective pulse wave signals corresponding to respective combinations of the lite-emitting elements, which have emitted light, and the light-receiving elements, which have received light, respectively; and

an optimum position identifying processor that selects a combination for a light-emitting element and a light-receiving element, which has outputted a pulse wave signal with a highest autocorrelation value among the respective autocorrelation values, an optimum combination,

wherein, in selecting an optimum combination again after an optimum combination of a light-emitting element and a light-receiving element is determined by the optimum position identifying processor, the processor for light emission causes a light-emitting element near the light-emitting element selected as the light-emitting of the optimum combination to emit light.

4. A measuring method of detecting a pulse wave signal indicating a change in a blood flow in a blood vessel of a patient by using light, comprising:

causing a plurality of light-emitting elements provided in a sensor module to emit light one after another;

calculating autocorrelation values of respective pulse wave signals corresponding to respective combinations of light-emitting elements that have emitted light, and light-receiving elements that have received light, respectively; and

selecting a combination of a light-emitting element and a light-receiving element, which has outputted a pulse wave signal with a highest autocorrelation value among the respective autocorrelation values, as an optimum combination,

wherein the step of calculating autocorrelation value includes slicing waveforms of pulse wave signals in an arbitrary period from the pulse wave signals, respectively, and obtaining an autocorrelation between the sliced waveforms and the pulse wave signals to thereby calculate autocorrelation values of the respective pulse wave signals.

5. A computer-readable medium encoded with a program that causes a computer to perform a measuring method of detecting a pulse wave signal indicating a change in a blood flow in the blood vessel of patient by using light, the program comprising the steps of:

a light-emitting step of causing a plurality of light-emitting elements provided in a sensor module to emit light one after another;

an input step of inputting respective pulse wave signals outputted from a plurality of light-receiving elements provided in the sensor module;

an autocorrelation value calculating step of calculating autocorrelation values of respective pulse wave signals corresponding to respective combinations of light-emitting elements that have emitted light, and the light-receiving elements that have received light, respectively; and

an optimum position identifying step of selecting a combination of a light-emitting element and a light-receiving element, which has outputted a pulse wave signal with a highest autocorrelation value among the respective autocorrelation values, as an optimum combination,

wherein the autocorrelation value calculating step includes slicing waveforms of pulse wave signals in an arbitrary period from the pulse wave signals, respectively, and obtaining an autocorrelation between the sliced waveforms and the pulse wave signals to thereby calculate autocorrelation values of the respective pulse wave signals.

6. A measuring method of detecting a pulse wave signal indicating a change in a blood flow in the blood vessel of a patient by using light, comprising:

causing a plurality of light-emitting elements provided in a sensor module to emit light one after another;

calculating autocorrelation values of respective pulse wave signals corresponding to respective combinations of the light-emitting elements, which have emitted light, and light-receiving elements, which have received light, respectively; and

selecting a combination of a light-emitting element and a light-receiving element, which has outputted a pulse wave signal with a highest autocorrelation value among the respective autocorrelation values, as an optimum combination,

wherein, in selecting an optimum combination again after an optimum combination of a light-emitting element and a light-receiving element is determined in the selecting step, a light-emitting element near the light-emitting element selected as the light-emitting of the optimum combination is caused to emit light.

7. A computer-related medium encoded with a program that causes a computer to perform a measuring method of detecting a pulse wave signal indicating a change in a blood flow in the blood vessel of patient by using light, the program comprising the steps of:

a light-emitting step of causing a plurality of light-emitting elements provided in a sensor module to emit light one after another;

an input step of inputting respective pulse wave signals outputted from light-receiving elements provided in the sensor module;

an autocorrelation value calculating step of calculating autocorrelation values of respective pulse wave signals corresponding to respective combinations of the light-emitting elements, which have emitted light, and the light-receiving elements, which have received light, respectively; and

an optimum position identifying step of selecting a combination of a light-emitting element and a light-receiving element, which has outputted a pulse wave signal with a highest autocorrelation value among the respective autocorrelation values, as an optimum combination,

wherein, in selecting an optimum combination again after an optimum combination of a light-emitting element and a light-receiving element is determined in the optimum position identifying step, a light-emitting element near the light-emitting element selected as the light-emitting of the optimum combination is caused to emit light.