JP2017140202A - Pulse wave detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an influence by a motion of a body and detect a pulse wave of a heart rate with a high degree of precision.SOLUTION: A pulse wave detection device 100 includes a first light emitter 11 for irradiating a first irradiation light of a first wavelength onto a living body, a second light emitter 12 for irradiating a second irradiation light of a second wavelength onto the living body, a first light receiver 13 for receiving a first reflection light which is the first irradiation light reflected by the living body, and outputting a first light reception signal, a second light receiver 14 for receiving a second reflection light which is the second irradiation light reflected by the living body, and outputting a second light reception signal, and a control unit 20 for detecting a frequency of a pulse wave based on the strength of the first light reception signal and the strength of the second light reception signal. The first irradiation light of the first wavelength and the second irradiation light of the second wavelength are near infrared lights.SELECTED DRAWING: Figure 4

Description

Translated fromJapanese

本発明は、心拍の脈波を検出する装置に関し、特に、生体に向けて光を照射し、生体からの反射光に基づいて脈波を検出する光学式の脈波検出装置に関する。  The present invention relates to an apparatus for detecting a pulse wave of a heartbeat, and more particularly to an optical pulse wave detection apparatus that irradiates light toward a living body and detects a pulse wave based on reflected light from the living body.

従来から、生体の皮膚に光を照射し、その反射光の光量の増減を検出することにより、心拍の脈波を検出する装置が知られている。例えば、特許文献１は、大掛かりな遮光構造がなくても使用可能な光学式の脈波計測装置を開示する。この脈波計測装置は、指に装着された状態で、青色ＬＥＤから指に向けて光を照射し、血管に届いて反射した光をフォトトランジスタによって受光する。その受光量は、血液の脈波によって生じる血量変化に対応する。ここで、青色ＬＥＤの発光波長は、３００ｎｍから７００ｎｍまでの波長領域であり、その発光波長ピークは、４５０ｎｍである。この波長領域の光は、赤外光に比べて血液中のヘモグロビンに吸光されやすいという特性が有り、血量の量、すなわちヘモグロビンの量に応じて、反射されてくる光の強度の変化が大きくなり、信号のＳＮ比が向上するという利点がある。  2. Description of the Related Art Conventionally, there has been known an apparatus for detecting a pulse wave of a heartbeat by irradiating light on the skin of a living body and detecting an increase or decrease in the amount of reflected light. For example,Patent Document 1 discloses an optical pulse wave measuring device that can be used without a large light shielding structure. This pulse wave measuring device irradiates light from a blue LED toward a finger while being worn on the finger, and receives light reflected by the blood vessel by a phototransistor. The amount of received light corresponds to a change in blood volume caused by a pulse wave of blood. Here, the emission wavelength of the blue LED is in a wavelength region from 300 nm to 700 nm, and the emission wavelength peak is 450 nm. Light in this wavelength region has a characteristic that it is more easily absorbed by hemoglobin in blood than infrared light, and the change in the intensity of reflected light is large depending on the amount of blood, that is, the amount of hemoglobin. Thus, there is an advantage that the signal-to-noise ratio of the signal is improved.

また、特許文献２は、太陽光の影響を除去して精度良く脈波を検出する脈波検出装置を開示する。この脈波検出装置は、人体の腕等に固定して利用するものであり、発光素子としての赤外ＬＥＤおよび緑色ＬＥＤと、受光素子としてのフォトダイオードとを備える。赤外ＬＥＤおよび緑色ＬＥＤが、それぞれ赤外光および緑色光を人体に向かって交互に照射し、この光の反射光をフォトダイオードが受光する。
フォトダイオードが出力した受光信号には、毛細動脈に当たって反射した脈波を示す信号（脈波成分）と、皮膚表面又は毛細動脈以外で反射した反射波の成分（反射波成分）との両成分が含まれている。人体に照射された赤外光の反射光は、体動成分と比較して脈拍成分が非常に小さく、緑色光の反射光は、脈拍成分と体動成分とがいずれも抽出できるので、各波長の反射光を比較することによって、脈波成分のみを抽出できる。Patent Document 2 discloses a pulse wave detection device that removes the influence of sunlight and accurately detects a pulse wave. This pulse wave detection device is used by being fixed to a human arm or the like, and includes an infrared LED and a green LED as light emitting elements, and a photodiode as a light receiving element. The infrared LED and the green LED alternately irradiate infrared light and green light toward the human body, respectively, and the photodiode receives the reflected light of this light.
The received light signal output from the photodiode includes both a signal indicating a pulse wave reflected by the capillary artery (pulse wave component) and a reflected wave component reflected from the skin surface or other than the capillary artery (reflected wave component). include. The reflected light of infrared light irradiated to the human body has a very small pulse component compared to the body motion component, and the reflected light of green light can extract both the pulse component and the body motion component. Only the pulse wave component can be extracted by comparing the reflected light.

また、特許文献３は、体動等の影響を受けることなく高精度に血圧を測定することができる血液測定装置を開示する。この血液測定装置は、近赤外光（例えば波長６４０ｎｍ）を皮膚へ照射し、皮膚深部にある橈骨動脈に至り、そこからの反射光を受光する光電センサによって、血管の容量変動に伴う吸光度の変化を血流量の相対変化（光電脈波）として検出する。体動センサとして青外光（例えば波長４２０ｎｍ）を皮膚へ照射し、皮膚表面での反射光の受光する体動センサによって、反射光の変動を体動の変化をして検出する。光電センサの出力波形から体動センサの出力波形を除去することによって、測定精度を向上させる。  Patent Document 3 discloses a blood measurement device capable of measuring blood pressure with high accuracy without being affected by body movement or the like. This blood measuring device irradiates the skin with near-infrared light (for example, wavelength 640 nm), reaches the radial artery in the deep part of the skin, and receives the reflected light from the radial artery, and the absorbance associated with the change in the volume of the blood vessel is measured. The change is detected as a relative change in blood flow (photoelectric pulse wave). The body motion sensor irradiates the skin with blue light (for example, a wavelength of 420 nm), and the body motion sensor that receives the reflected light on the skin surface detects the fluctuation of the reflected light by changing the body motion. Measurement accuracy is improved by removing the output waveform of the body motion sensor from the output waveform of the photoelectric sensor.

特開２００５−１２５１０６号公報JP 2005-125106 A特開２００５−１６０６４１号公報Japanese Patent Laid-Open No. 2005-160641特開２００２−３６９８０５号公報JP 2002-369805 A

上述したように、生体の皮膚に光を照射し、その反射光の増減により心拍の脈波を検出する際、反射光の光量は、他の体の動きによっても増減するために、かかる体の動きによる影響を低減させる必要がある。本願発明者らは、反射光の光量を計測する際の体の動きによる影響を少なくすると共に心拍の脈波を高精度に検出ことを目的として鋭意検討した結果、照射する波長におけるヘモグロビンと水の吸光率の差に着目し、多くの実験を重ねることで、上記目的を達成しうることを見出し、本発明を完成するに至った。
本発明は、所定の波長の異なる２つの光を用いて、体の動きによる影響を少なくすると共に、心拍の脈波を高精度に検出する光学式の脈波検出装置を提供するものである。As described above, when irradiating light on the skin of a living body and detecting a pulse wave of a heartbeat by increasing or decreasing the reflected light, the amount of reflected light increases or decreases depending on the movement of another body. It is necessary to reduce the influence of movement. The inventors of the present application have made extensive studies for the purpose of reducing the influence of body movement when measuring the amount of reflected light and detecting heartbeat pulse waves with high accuracy. By paying attention to the difference in absorbance and repeating a number of experiments, the inventors have found that the above object can be achieved, and have completed the present invention.
The present invention provides an optical pulse wave detection device that uses two lights having different predetermined wavelengths to reduce the influence of body movement and to detect heartbeat pulse waves with high accuracy.

上記課題を解決するために、生体に対して第１波長の第１照射光を照射する第１発光器と、生体に対して第２波長の第２照射光を照射する第２発光器と、第１照射光が生体によって反射された第１反射光を受光し、第１受光信号を出力する第１受光器と、第２照射光が生体によって反射された第２反射光を受光し、第２受光信号を出力する第２受光器と、第１受光信号の強度と第２受光信号の強度に基づいて脈波の周波数を検出する制御部と、を備え、第１波長の第１照射光および第２波長の第２照射光は近赤外光である、脈波検出装置が提供される。
これによれば、ヘモグロビンと水に対する吸光率が互いに異なる２つの波長の近赤外光を照射し、その反射光を分析することで、体の動きによる影響が少なくなり、精度良く脈波を検出する光学式の脈波検出装置を提供できる。In order to solve the above problem, a first light emitter that irradiates a living body with a first irradiation light having a first wavelength, a second light emitter that irradiates a living body with a second irradiation light having a second wavelength, The first irradiation light receives the first reflected light reflected by the living body and outputs a first received light signal; the second irradiation light receives the second reflected light reflected by the living body; A second light receiving device that outputs two light receiving signals, and a controller that detects the frequency of the pulse wave based on the intensity of the first light receiving signal and the intensity of the second light receiving signal, and the first irradiation light having the first wavelength. A pulse wave detection device is provided in which the second irradiation light having the second wavelength is near-infrared light.
According to this, by irradiating two wavelengths of near-infrared light with different absorption rates for hemoglobin and water, and analyzing the reflected light, the influence of the movement of the body is reduced, and the pulse wave is detected accurately. An optical pulse wave detection device can be provided.

さらに、第１波長は８３５〜９１０ｎｍであり、前記第２波長は７４０〜８３０ｎｍであることを特徴としてもよい。
これによれば、実験により確認された波長に限定することで、より精度良く脈波を検出することができる。Further, the first wavelength may be 835 to 910 nm, and the second wavelength may be 740 to 830 nm.
According to this, the pulse wave can be detected with higher accuracy by limiting to the wavelength confirmed by the experiment.

さらに、第１発光器と第２発光器は交互に第１照射光と第２照射光を照射し、第１受光器と第２受光器は１つの受光素子からなることを特徴としてもよい。
これによれば、受光器の数を削減することで脈波検出装置のコストを安くすることができる。Further, the first light emitter and the second light emitter may alternately emit the first irradiation light and the second irradiation light, and the first light receiver and the second light receiver may be composed of one light receiving element.
According to this, the cost of the pulse wave detection device can be reduced by reducing the number of light receivers.

以上説明したように、本発明によれば、所定の波長の異なる２つの光を用いて体の動きによる影響を少なくして、検出精度の高い光学式の脈波検出装置を提供できる。  As described above, according to the present invention, it is possible to provide an optical pulse wave detection device with high detection accuracy by using two lights having different predetermined wavelengths to reduce the influence of body movement.

９５０ｎｍと８７０ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 950 nm and 870 nm.９５０ｎｍと８００ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 950 nm and 800 nm.９５０ｎｍと７５０ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 950 nm and 750 nm.９５０ｎｍと７００ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 950 nm and 700 nm.８７０ｎｍと８００ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows the frequency distribution at the time of experimenting with the combination of the light of a wavelength of 870 nm and 800 nm.８７０ｎｍと７５０ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 870 nm and 750 nm.８７０ｎｍと７００ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 870 nm and 700 nm.８００ｎｍと７５０ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 800 nm and 750 nm.８００ｎｍと７００ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 800 nm and 700 nm.７５０ｎｍと７００ｎｍの波長の光の組合せで実験した場合の周波数分布を示すグラフ。The graph which shows frequency distribution at the time of experimenting with the combination of the light of a wavelength of 750 nm and 700 nm.表１のＳ／Ｎ比の値に基づく等高線グラフ。The contour graph based on the value of S / N ratio of Table 1.本発明に係る脈波検出装置の使用形態を示す説明図。（Ａ）指に接触させて使用する場合、（Ｂ）指から離して使用する場合。Explanatory drawing which shows the usage condition of the pulse-wave detection apparatus which concerns on this invention. (A) When used in contact with a finger, (B) When used away from a finger.本発明に係る第一実施例の脈波検出装置の構成を示す説明図。Explanatory drawing which shows the structure of the pulse-wave detection apparatus of 1st Example which concerns on this invention.本発明に係る第一実施例の脈波検出装置の制御部のブロック図。The block diagram of the control part of the pulse-wave detection apparatus of 1st Example which concerns on this invention.本発明に係る第一実施例の脈波検出装置の信号処理回路のブロック図。The block diagram of the signal processing circuit of the pulse-wave detection apparatus of 1st Example which concerns on this invention.本発明に係る第一実施例の脈波検出装置における動作を示すフローチャート。The flowchart which shows the operation | movement in the pulse-wave detection apparatus of 1st Example which concerns on this invention.本発明に係る第一実施例の脈波検出装置におけるサンプリングを説明する説明図。Explanatory drawing explaining the sampling in the pulse-wave detection apparatus of 1st Example which concerns on this invention.本発明に係る第二実施例の脈波検出装置の構成を示す説明図。Explanatory drawing which shows the structure of the pulse-wave detection apparatus of 2nd Example which concerns on this invention.本発明に係る第二実施例の脈波検出装置の制御部のブロック図。The block diagram of the control part of the pulse-wave detection apparatus of 2nd Example which concerns on this invention.本発明に係る第二実施例の脈波検出装置の信号処理回路のブロック図。The block diagram of the signal processing circuit of the pulse-wave detection apparatus of 2nd Example which concerns on this invention.本発明に係る第二実施例の脈波検出装置における動作を示すフローチャート。The flowchart which shows the operation | movement in the pulse-wave detection apparatus of 2nd Example which concerns on this invention.本発明に係る第二実施例の脈波検出装置におけるサンプリングを説明する説明図。Explanatory drawing explaining the sampling in the pulse-wave detection apparatus of 2nd Example which concerns on this invention.

＜照射する光の波長について＞
波長２００ｎｍから１０μｍでの光に対して、生体内に存在する主な光吸収物質は、水と血液中のヘモグロビンであり、それらの吸収スペクトルは波長に強く依存することが知られている。ヘモグロビンは、波長が７００ｎｍ以下の光に対して強い吸収を持ち、水は、２μｍよりも波長が長い中赤外光および遠赤外光に対して強い吸収を持つ。一方、波長がおよそ７００ｎｍから２μｍまでの近赤外光に対してはヘモグロビンと水の吸収が弱いため、近赤外光は、生体組織に深く浸透する。<About the wavelength of the irradiated light>
It is known that the main light-absorbing substances existing in the living body with respect to light with a wavelength of 200 nm to 10 μm are water and hemoglobin in blood, and their absorption spectra strongly depend on the wavelength. Hemoglobin has strong absorption with respect to light having a wavelength of 700 nm or less, and water has strong absorption with respect to mid-infrared light and far-infrared light having a wavelength longer than 2 μm. On the other hand, since the absorption of hemoglobin and water is weak for near infrared light having a wavelength of about 700 nm to 2 μm, the near infrared light penetrates deeply into the living tissue.

心拍の脈波を光学的に検出するためには、光が動脈に届くことが必要である。そのためには、水による吸光率がより低い光である９００ｎｍ以下の光を使うことが必要である。また、静脈の中のヘモグロビンによる吸光率が大きすぎても深い位置にある動脈に届く前に減衰してしまうので、光の波長が７００ｎｍ以下であると水による吸光率はより小さいが、ヘモグロビンによる吸光率が高くなり適切ではない。したがって、波長が７００ｎｍ〜９００ｎｍ程度の光であれば、水およびヘモグロビン両方による吸光率が小さい。よって、動脈内に存するヘモグロビンの変動を検出するためには、７００ｎｍ〜９００ｎｍの波長の近赤外光を使用することが好ましい。この動脈内に存するヘモグロビンの変動を検出するための光の波長を、本明細書では第１波長という。  In order to optically detect a pulse wave of a heartbeat, it is necessary that light reaches an artery. For that purpose, it is necessary to use light of 900 nm or less, which is light having a lower light absorption rate. In addition, even if the absorbance due to hemoglobin in the vein is too large, it will attenuate before reaching the artery in the deep position, so if the wavelength of light is 700 nm or less, the absorbance due to water is smaller, Absorbance increases and is not appropriate. Therefore, if the light has a wavelength of about 700 nm to 900 nm, the light absorption rate by both water and hemoglobin is small. Therefore, it is preferable to use near infrared light having a wavelength of 700 nm to 900 nm in order to detect a change in hemoglobin present in the artery. The wavelength of light for detecting the fluctuation of hemoglobin existing in the artery is referred to as a first wavelength in this specification.

本発明では、第１波長と、第１波長とは異なる波長（以下、第２波長と言う）の光も使用して、体の動きを相殺する。第１波長との差分を検出するための第２波長は、心拍によるヘモグロビンの変動による反射光の変動においては第１波長の反射光の変動との差が大きくなる波長であり、かつ、体の動きに伴う変動による反射光の変動においては第１波長の反射光の変動との差が小さくなる波長である。したがって、第２波長は、水の吸光率において第１波長と同程度の吸光率を有する波長が適している。そうすると、第２波長も、７００ｎｍ〜９００ｎｍの波長の近赤外光を使用することが好ましい。  In the present invention, the movement of the body is canceled by using the first wavelength and light having a wavelength different from the first wavelength (hereinafter referred to as the second wavelength). The second wavelength for detecting the difference from the first wavelength is a wavelength at which a difference between the reflected light of the first wavelength and the fluctuation of the reflected light due to the hemoglobin fluctuation due to the heartbeat becomes large, and In the fluctuation of the reflected light due to the fluctuation caused by the movement, the difference is smaller than the fluctuation of the reflected light of the first wavelength. Accordingly, the second wavelength is suitably a wavelength having an absorbance similar to that of the first wavelength in the water absorbance. Then, it is preferable to use near infrared light having a wavelength of 700 nm to 900 nm as the second wavelength.

しかし、第２波長は、第１波長の吸光率を同程度とするためには、第１波長に近ければ近いほどよいことになるが、第１波長の吸光率と差を大きくするためには、第１波長から離れれば離れるほどよいこととなり、第２波長は、一義的に定まらない。そこで、発明者らは、様々な実験を行った。  However, for the second wavelength, the closer to the first wavelength, the better in order to make the absorbance at the first wavelength comparable, but to increase the difference from the absorbance at the first wavelength. The farther away from the first wavelength, the better. The second wavelength is not uniquely determined. Therefore, the inventors conducted various experiments.

図１Ａ〜図１Ｊは、各波長の光を出力する発光ダイオード（ＬＥＤ）を使用し、実験を行った結果である。使用したＬＥＤの中心波長は、９５０ｎｍ、８７０ｎｍ、８００ｎｍ、７５０ｎｍ、７００ｎｍである。図１Ａが、第１波長に９５０ｎｍ、第２波長に８７０ｎｍを使用した場合の結果であり、以下同様に、図１Ｂが、第１波長に９５０ｎｍ、第２波長に８００ｎｍを、図１Ｃが、第１波長に９５０ｎｍ、第２波長に７５０ｎｍを、図１Ｄが、第１波長に９５０ｎｍ、第２波長に７００ｎｍを、図１Ｅが、第１波長に８７０ｎｍ、第２波長に８００ｎｍを、図１Ｆが、第１波長に８７０ｎｍ、第２波長に７５０ｎｍを、図１Ｇが、第１波長に８７０ｎｍ、第２波長に７００ｎｍを、図１Ｈが、第１波長に８００ｎｍ、第２波長に７５０ｎｍを、図１Ｉが、第１波長に８００ｎｍ、第２波長に７００ｎｍを、図１Ｊが、第１波長に７５０ｎｍ、第２波長に７００ｎｍを使用した場合の結果である。  1A to 1J show results of experiments using light emitting diodes (LEDs) that output light of each wavelength. The center wavelengths of the used LEDs are 950 nm, 870 nm, 800 nm, 750 nm, and 700 nm. FIG. 1A shows the results when 950 nm is used for the first wavelength and 870 nm is used for the second wavelength. Similarly, FIG. 1B shows 950 nm for the first wavelength, 800 nm for the second wavelength, and FIG. FIG. 1D shows 950 nm for the first wavelength, 750 nm for the second wavelength, FIG. 1D shows 950 nm for the first wavelength, 700 nm for the second wavelength, FIG. 1E shows 870 nm for the first wavelength, 800 nm for the second wavelength, and FIG. FIG. 1G shows 870 nm for the first wavelength, 750 nm for the second wavelength, FIG. 1H shows 870 nm for the first wavelength, 700 nm for the second wavelength, FIG. 1H shows 800 nm for the first wavelength, 750 nm for the second wavelength, and FIG. FIG. 1J shows the results when using the first wavelength of 800 nm, the second wavelength of 700 nm, and FIG. 1J using the first wavelength of 750 nm and the second wavelength of 700 nm.

これらの図を描くために、実験では、第１波長と第２波長の光を生体に照射し、受光素子によりその反射光の受光値を取得した。そして、その２つの受光値の比率（Ｒａｔｉｏ）に対して、直流成分のノイズを取り除くために平滑化微分処理を行った後、周波数成分を抽出するために高速フーリエ変換処理を行った。  In order to draw these figures, in the experiment, the living body was irradiated with light of the first wavelength and the second wavelength, and the received light value of the reflected light was obtained by the light receiving element. Then, a smoothing differentiation process was performed on the ratio (Ratio) of the two received light values to remove noise of the DC component, and then a fast Fourier transform process was performed to extract the frequency component.

図１Ａでは、実線矢印が示す心拍の脈波（脈拍）の周期に対応する１Ｈｚ辺りでは多少のピークは示すものの大きなピークを示すとは言えず、２Ｈｚ辺りで最も大きなピークを示す。２Ｈｚは、１Ｈｚの高周波成分とも推測できるが、精度良く脈波のみを検出することを目的としているので、２Ｈｚのピークは無視するものとする。なお、本図では、破線矢印が示す呼吸の周期に対応する０．３〜０．４Ｈｚ辺りでもピークは示していない。そうすると、第１波長に９５０ｎｍ、第２波長に８７０ｎｍを使用した場合、受光した光の中には脈拍の周期の反射光はあまり含まれていないこととなり、精度良く脈波のみを検出する波長の組合せとしては適切ではないと言える。  In FIG. 1A, although a slight peak is shown around 1 Hz corresponding to the period of the pulse wave (pulse) of the heartbeat indicated by the solid line arrow, it cannot be said that a large peak is shown, and the largest peak is shown around 2 Hz. Although 2 Hz can be estimated as a high-frequency component of 1 Hz, the purpose is to detect only the pulse wave with high accuracy, so the peak at 2 Hz is ignored. In this figure, no peak is shown even in the vicinity of 0.3 to 0.4 Hz corresponding to the breathing cycle indicated by the dashed arrow. Then, when 950 nm is used for the first wavelength and 870 nm is used for the second wavelength, the received light does not contain much reflected light of the pulse period, and the wavelength for detecting only the pulse wave with high accuracy is obtained. It can be said that the combination is not appropriate.

図１Ｂでは、脈拍の周期に対応する実線矢印の１Ｈｚ辺りと、呼吸の周期に対応する破線矢印の０．３〜０．４Ｈｚ辺りとでピークを示す。そうすると、第１波長に９５０ｎｍ、第２波長に８００ｎｍを使用した場合、受光した光の中には脈拍の周期の反射光と呼吸の周期の反射光が同程度に含まれていることとなり、呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出する波長の組合せとしては適切ではないと言える。  In FIG. 1B, a peak is shown around 1 Hz of a solid line arrow corresponding to the pulse period and around 0.3 to 0.4 Hz of a broken line arrow corresponding to the breathing period. Then, when 950 nm is used for the first wavelength and 800 nm is used for the second wavelength, the received light contains the reflected light of the pulse period and the reflected light of the respiration period to the same extent. It can be said that it is not appropriate as a combination of wavelengths for detecting only the pulse wave with high accuracy by reducing the influence of the body movement.

図１Ｃでは、脈拍の周期に対応する実線矢印の１Ｈｚ辺りのピークは、呼吸の周期に対応する破線矢印の０．３〜０．４Ｈｚ辺りのピークよりも高く、上記の波長の組合せに比べれば比較的良い組合せとも評価できるが、精度良く脈波のみを検出する波長の組合せとしては適切ではないと言える。図１Ｄでは、同様に、脈拍の周期に対応する実線矢印の１Ｈｚ辺りのピークは、呼吸の周期に対応する破線矢印の０．３〜０．４Ｈｚ辺りのピークよりも高いと言えるが、精度良く脈波のみを検出する波長の組合せとしては適切ではないと言える。そうすると、図１Ａ〜図１Ｄに示す、第１波長に９５０ｎｍを使い、第２波長に８７０〜７００ｎｍを使用した場合は、呼吸のような体の動きによる影響を少なくして脈波のみを検出する波長の組合せとしては適切ではないと言える。  In FIG. 1C, the peak around 1 Hz of the solid line arrow corresponding to the pulse period is higher than the peak around 0.3 to 0.4 Hz of the broken line arrow corresponding to the breathing period, compared to the combination of the above wavelengths. Although it can be evaluated as a relatively good combination, it can be said that it is not appropriate as a combination of wavelengths for detecting only a pulse wave with high accuracy. In FIG. 1D, similarly, it can be said that the peak around 1 Hz of the solid arrow corresponding to the pulse cycle is higher than the peak around 0.3 to 0.4 Hz of the dashed arrow corresponding to the breathing cycle, but with high accuracy. It can be said that the combination of wavelengths for detecting only the pulse wave is not appropriate. Then, when 950 nm is used for the first wavelength and 870 to 700 nm is used for the second wavelength as shown in FIGS. 1A to 1D, only the pulse wave is detected with less influence of body movement such as respiration. It can be said that the combination of wavelengths is not appropriate.

図１Ｅでは、脈拍の周期に対応する実線矢印の１Ｈｚ辺りに非常に高いピークを示し、他の周期においてはピークを示していない。そうすると、第１波長に８７０ｎｍ、第２波長に８００ｎｍを使用した場合、受光した光の中には脈拍の周期の反射光が非常に多く含まれ、他の周期の反射光はほとんど含まれていないことになる。したがって、第１波長を８７０ｎｍとして、第２波長を８００ｎｍとした波長の組合せは、呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出する波長の組合せとして適切であると言える。  In FIG. 1E, a very high peak is shown around 1 Hz of the solid line arrow corresponding to the pulse period, and no peak is shown in other periods. Then, when 870 nm is used for the first wavelength and 800 nm is used for the second wavelength, the received light contains very much reflected light of the pulse period, and hardly contains reflected light of other periods. It will be. Therefore, a wavelength combination in which the first wavelength is set to 870 nm and the second wavelength is set to 800 nm is appropriate as a combination of wavelengths for accurately detecting only the pulse wave with less influence of body movement such as respiration. I can say that.

図１Ｆでは、脈拍の周期に対応する実線矢印の１Ｈｚ辺りに非常に高いピークを示し、他の周期においてはピークを示していない。図１Ｇにおいても、脈拍の周期に対応する実線矢印の１Ｈｚ辺りに非常に高いピークを示し、他の周期においてはピークを示していない。そうすると、図１Ｅ〜図１Ｇに示す、第１波長に８７０ｎｍ、第２波長に８００〜７００ｎｍを使用した場合、受光した光の中には脈拍の周期の反射光が非常に多く含まれ、他の周期の反射光はほとんど含まれていないこととなり、呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出する波長の組合せとして適切であると言える。  In FIG. 1F, a very high peak is shown around 1 Hz of the solid line arrow corresponding to the pulse period, and no peak is shown in other periods. Also in FIG. 1G, a very high peak is shown around 1 Hz of the solid line arrow corresponding to the pulse period, and no peak is shown in other periods. Then, when 870 nm is used for the first wavelength and 800 to 700 nm is used for the second wavelength, as shown in FIGS. 1E to 1G, the received light contains very much reflected light of the pulse period, The reflected light of the period is hardly included, and it can be said that it is suitable as a combination of wavelengths for detecting only the pulse wave with high accuracy while reducing the influence of body movement such as respiration.

図１Ｈでは、脈拍の周期に対応する実線矢印の１Ｈｚ辺りに高いピークを示し、呼吸の周期に対応する破線矢印の０．３〜０．４Ｈｚ辺りに多少多く含まれることを示しているものの、１Ｈｚ辺りのピークに比べればかなり低い。そうすると、第１波長に８００ｎｍ、第２波長に７５０ｎｍを使用した場合、受光した光の中には脈拍の周期の反射光が非常に多く含まれ、他の周期の反射光はほとんど含まれていないことになる。したがって、第１波長を８００ｎｍとして、第２波長を７５０ｎｍとした波長の組合せは、呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出する波長の組合せとして適切であると言える。  In FIG. 1H, a high peak is shown around 1 Hz of the solid line arrow corresponding to the pulse period, and it is shown that it is included a little around 0.3 to 0.4 Hz of the broken line arrow corresponding to the breathing period. It is considerably lower than the peak around 1 Hz. Then, when 800 nm is used for the first wavelength and 750 nm is used for the second wavelength, the received light contains very much reflected light of the pulse period, and hardly contains reflected light of other periods. It will be. Therefore, a wavelength combination in which the first wavelength is set to 800 nm and the second wavelength is set to 750 nm is appropriate as a combination of wavelengths for detecting only the pulse wave with high accuracy while reducing the influence of body movement such as respiration. I can say that.

図１Ｉでは、呼吸の周期に対応する破線矢印の０．３〜０．４Ｈｚ辺りと脈拍の周期に対応する実線矢印の１Ｈｚ辺りに同程度のピークを示す。そうすると、第１波長に８００ｎｍ、第２波長に７００ｎｍを使用した場合、受光した光の中には脈拍の周期の反射光と呼吸の周期の反射光が同程度に含まれていることとなり、呼吸のような体の動きによる影響を少なくして脈波のみを検出する波長の組合せとしては適切ではないと言える。  In FIG. 1I, the same level of peaks are shown around 0.3 to 0.4 Hz of the broken line arrow corresponding to the respiratory cycle and around 1 Hz of the solid line arrow corresponding to the pulse period. Then, when 800 nm is used for the first wavelength and 700 nm is used for the second wavelength, the received light contains the reflected light of the pulse period and the reflected light of the respiration period to the same extent. It can be said that it is not appropriate as a combination of wavelengths for detecting only the pulse wave by reducing the influence of the body movement.

図１Ｊでは、呼吸の周期に対応する破線矢印の０．３〜０．４Ｈｚ辺りに多少ピークを示し、脈拍の周期に対応する実線矢印の１Ｈｚ辺りにピークはほとんどない。そうすると、第１波長に７５０ｎｍ、第２波長に７００ｎｍを使用した場合、脈波をほとんど検出できないので、波長の組合せとして適切でないと言える。  In FIG. 1J, there is a slight peak around 0.3 to 0.4 Hz of the dashed arrow corresponding to the breathing cycle, and there is almost no peak around 1 Hz of the solid arrow corresponding to the pulse cycle. Then, when 750 nm is used for the first wavelength and 700 nm is used for the second wavelength, pulse waves can hardly be detected, so it can be said that the combination of wavelengths is not appropriate.

上述したことをまとめると、実際に実験を行った２つの波長の組合せとしては、８７０ｎｍと８００ｎｍ、８７０ｎｍと７５０ｎｍ、８７０ｎｍと７００ｎｍ、８００ｎｍと７５０ｎｍ、８００ｎｍと７００ｎｍ、７５０ｎｍと７００ｎｍ、の組合せにおいて、受光した光の中には脈拍の周期の反射光が非常に多く含まれ、他の周期の反射光はほとんど含まれていないこととなり、呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出する波長の組合せとして適切であると言える。  In summary, the two wavelengths actually tested are 870 nm and 800 nm, 870 nm and 750 nm, 870 nm and 700 nm, 800 nm and 750 nm, 800 nm and 700 nm, and 750 nm and 700 nm. The reflected light contains a very large amount of reflected light of the pulse period, and hardly contains the reflected light of other periods. The influence of body movement such as breathing is reduced and the pulse is accurately detected. It can be said that it is suitable as a combination of wavelengths for detecting only waves.

しかし、上記の波長は実験に使用されたＬＥＤのスペクトル分布におけるピーク波長であり、実際には、そのピーク波長をほぼ中央値として、半値幅３０ｎｍ〜４０ｎｍ程度を示すのが通常のＬＥＤのスペクトル分布の仕様である。そうすると、ある程度の波長幅を有して適切であると言うことが可能である。たとえば、最も際立った差を示した８７０ｎｍと８００ｎｍの組合せの場合、半値幅を考慮すれば、第１波長が８５０ｎｍ〜８９０ｎｍ程度であり、第２波長が７８０ｎｍ〜８２０ｎｍ程度であれば、呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出することができると考えられる。同様に、８７０ｎｍと７５０ｎｍの組合せの場合、半値幅を考慮すれば、第１波長が８５０ｎｍ〜８９０ｎｍ程度であり、第２波長が７３０ｎｍ〜７７０ｎｍ程度であれば、呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出することができると考えられる。  However, the above-mentioned wavelength is the peak wavelength in the spectrum distribution of the LED used in the experiment. In practice, the peak wavelength is approximately the median, and the half-width of about 30 nm to 40 nm is shown as a normal LED spectrum distribution. This is the specification. Then, it can be said that it is appropriate with a certain wavelength width. For example, in the case of the combination of 870 nm and 800 nm, which shows the most remarkable difference, if the first half wavelength is about 850 nm to 890 nm and the second wavelength is about 780 nm to 820 nm, the half-width is considered. It is considered that only the pulse wave can be detected accurately with less influence of the body movement. Similarly, in the case of the combination of 870 nm and 750 nm, if the half-value width is taken into consideration, if the first wavelength is about 850 nm to 890 nm and the second wavelength is about 730 nm to 770 nm, the influence of body movement such as respiration It is considered that only the pulse wave can be detected with high accuracy.

表１は、第１波長をＶＳ１、第２波長をＶＳ２として、上述したように、２つの受光値の比率（Ｒａｔｉｏ）に対して高速フーリエ変換処理を行った結果において、周波数が１以上１．５Ｈｚ未満におけるピーク値をＳ欄に、０以上１．０Ｈｚ未満におけるピーク値をＮ欄に記載して、Ｓ欄に記載されたピーク値をＮ欄に記載されたピーク値で除したものをＳ／Ｎ比として算出したものである。すなわち、このＳ／Ｎ比は、脈波に対応する周波数帯における信号の大きさをＳｉｇｎａｌとみなし、呼吸に対応する周波数帯における信号の大きさをＮｏｉｓｅとみなしたＳ／Ｎ比である。

Table 1 shows that the first wavelength is VS1 and the second wavelength is VS2, and as described above, the result of performing the fast Fourier transform process on the ratio (Ratio) of the two received light values indicates that the frequency is 1 or more. The peak value at less than 5 Hz is written in the S column, the peak value at 0 to less than 1.0 Hz is written in the N column, and the peak value written in the S column is divided by the peak value written in the N column. / N ratio. That is, this S / N ratio is an S / N ratio in which the magnitude of the signal in the frequency band corresponding to the pulse wave is regarded as Signal and the magnitude of the signal in the frequency band corresponding to respiration is regarded as Noise.

図２は、表１のＳ／Ｎ比の値に基づいて、所謂等高線グラフを描いたものである。値の無い部分（一点鎖線より右下側）はＳ／Ｎ比をゼロとし、Ｓ／Ｎ比が０〜２は白、２〜４はグレー、４〜６は黒で描いた。Ｓ／Ｎ比の評価では、４以上であれば呼吸のような体の動きによる影響を少なくして精度良く脈波のみを検出することができるとした。したがって、黒く描かれた周波数の領域が精度良く脈波のみを検出することができる領域である。そうすると、８３５〜９１０ｎｍの第１波長（ＶＳ１）と７４０〜８３０ｎｍの第２波長（ＶＳ２）の組合せであれば、精度良く脈波のみを検出することができると言える。この組合せの領域（点線で囲まれた矩形の領域）には、一部にグレーの領域を含むが、黒の領域に近いので、グレーの領域であっても十分精度良く脈波のみを検出することができると評価できる。  FIG. 2 depicts a so-called contour graph based on the value of the S / N ratio in Table 1. A portion having no value (lower right side of the alternate long and short dash line) was drawn with an S / N ratio of zero, with the S / N ratio being 0 to 2 in white, 2 to 4 in gray, and 4 to 6 in black. In the evaluation of the S / N ratio, when it is 4 or more, it is assumed that only the pulse wave can be accurately detected with less influence of body movement such as breathing. Therefore, the frequency region drawn in black is a region where only the pulse wave can be detected with high accuracy. If it does so, if it is a combination of the 1st wavelength (VS1) of 835-910 nm and the 2nd wavelength (VS2) of 740-830 nm, it can be said that only a pulse wave can be detected accurately. This combination area (rectangular area surrounded by a dotted line) includes a gray area in part, but it is close to the black area, so only the pulse wave is detected with sufficient accuracy even in the gray area. Can be evaluated.

以下では、図面を参照しながら、本発明に係る各実施例について説明する。
＜第一実施例＞
図３〜図８を参照し、本実施例における脈波検出装置１００を説明する。脈波検出装置１００は、発光器と受光器を有する検知部１０と、発光器が照射した光が生体（指）Ｂで反射し受光器が受光した反射光の強度に基づいて心拍による変動（脈波）を検出する制御部２０とを備える。脈波検出装置１００の検知部１０は、図３（Ａ）が示すように生体（指）Ｂに接触させて使用してもよいし、図３（Ｂ）が示すように生体（指）Ｂに接触させず離して使用してもよい。また、検知部１０が検知する生体の部位は、指に限られず、顔や胴体など他の部位であってもよい。Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Example>
With reference to FIGS. 3-8, the pulse-wave detection apparatus 100 in a present Example is demonstrated. The pulsewave detection device 100 includes adetector 10 having a light emitter and a light receiver, and fluctuations due to heartbeats based on the intensity of reflected light reflected by the living body (finger) B when the light emitted from the light emitter is reflected by the living body (finger) B ( And acontrol unit 20 that detects a pulse wave). Thedetection unit 10 of the pulsewave detection device 100 may be used in contact with the living body (finger) B as shown in FIG. 3A, or the living body (finger) B as shown in FIG. It is also possible to use it without contacting it. Further, the part of the living body detected by thedetection unit 10 is not limited to the finger, and may be another part such as a face or a torso.

たとえば、脈波検出装置１００は、車両を運転する運転者の脈波を検出する場合は、ルームミラーやハンドルなどに設けられて、顔に照射された光の反射光に基づいて脈波を検出してもよい。また、脈波検出装置１００は、椅子やソファ、ベッドなどの胴体が接触する部分に設けられて、使用者の胴体に向けて衣服を通過する強い光を照射し、その反射光に基づいて脈波を検出してもよい。  For example, when detecting the pulse wave of the driver who drives the vehicle, the pulsewave detection device 100 is provided in a room mirror, a handle, etc., and detects the pulse wave based on the reflected light of the light applied to the face. May be. The pulsewave detection device 100 is provided at a portion where the body such as a chair, a sofa, or a bed comes into contact, irradiates the user's body with strong light passing through the clothes, and based on the reflected light, the pulse wave is detected. Waves may be detected.

図４に示すように、脈波検出装置１００の検知部１０は、生体（指）Ｂに対して第１波長の第１照射光を照射する第１発光器１１と、生体（指）Ｂに対して第２波長の第２照射光を照射する第２発光器１２と、第１照射光が生体（指）Ｂによって反射された第１反射光を受光し、第１受光信号を出力する第１受光器１３と、第２照射光が生体（指）Ｂによって反射された第２反射光を受光し、第２受光信号を出力する第２受光器１４と、を備える。第１発光器１１および第２発光器１２は、電気信号を光信号に変換する発光素子であり、たとえば、コスト面で有利な発光ダイオード（ＬＥＤ）や、大きな出力が可能な半導体レーザである。第１受光器１３および第２受光器１４は、受信した光信号を電気信号に復調する受光素子であり、たとえば、フォトダイオードである。  As shown in FIG. 4, thedetection unit 10 of the pulsewave detection device 100 applies thefirst light emitter 11 that irradiates the living body (finger) B with the first irradiation light having the first wavelength, and the living body (finger) B. On the other hand, thesecond light emitter 12 that emits the second irradiation light having the second wavelength, the first reflected light that is reflected by the living body (finger) B, and the first light reception signal is output. 1light receiver 13, and 2ndlight receiver 14 which receives the 2nd reflected light in which 2nd irradiation light was reflected by the biological body (finger) B, and outputs a 2nd light reception signal. Thefirst light emitter 11 and thesecond light emitter 12 are light emitting elements that convert an electric signal into an optical signal, and are, for example, a light emitting diode (LED) that is advantageous in terms of cost, or a semiconductor laser capable of large output. Thefirst light receiver 13 and thesecond light receiver 14 are light receiving elements that demodulate received optical signals into electrical signals, and are, for example, photodiodes.

第１発光器１１および第２発光器１２は、制御部２０と信号線で接続され、プリント配線基板１９上に配置された投光回路部品１７により実際に駆動されて、所定の波長で発光する。発光された光は、投光窓１５を通って生体（指）Ｂに照射される。第１受光器１３および第２受光器１４は、照射された光が生体（指）Ｂに反射して受光窓１６を通って戻ってきた反射光を受光する。第１受光器１３および第２受光器１４は、受光した反射光を復調した電気信号をプリント配線基板１９上の受光回路部品１８に渡す。受光回路部品１８は信号線により制御部２０と接続されており、第１受光器１３および第２受光器１４が復調した電気信号は、制御部２０に渡される。  Thefirst light emitter 11 and thesecond light emitter 12 are connected to thecontrol unit 20 through signal lines, and are actually driven by the light projectingcircuit component 17 disposed on the printedwiring board 19 to emit light at a predetermined wavelength. . The emitted light is irradiated to the living body (finger) B through theprojection window 15. Thefirst light receiver 13 and thesecond light receiver 14 receive the reflected light that is reflected from the irradiatedlight 16 and returned through thelight receiving window 16. Thefirst light receiver 13 and thesecond light receiver 14 pass an electric signal obtained by demodulating the received reflected light to the lightreceiving circuit component 18 on the printedwiring board 19. The lightreceiving circuit component 18 is connected to thecontrol unit 20 by a signal line, and the electric signal demodulated by the firstlight receiving device 13 and the secondlight receiving device 14 is passed to thecontrol unit 20.

第１受光器１３は、第１発光器１１が照射した第１波長の第１照射光が生体（指）Ｂによって反射された第１反射光を受光し、第１受光信号を出力する。第２受光器１４は、第２発光器１２が照射した第２波長の第２照射光が生体（指）Ｂによって反射された第１反射光を受光し、第１受光信号を出力する。このように、本実施では、第１発光器１１と第１受光器１３、および第２発光器１２と第２受光器１４とがそれぞれ対応しており、第１受光器１３と第２受光器１４は、それぞれ第１波長と第２波長を選択的に透過するフィルタを用いる。  Thefirst light receiver 13 receives the first reflected light reflected by the living body (finger) B with the first irradiation light having the first wavelength irradiated by thefirst light emitter 11 and outputs a first light reception signal. Thesecond light receiver 14 receives the first reflected light reflected by the living body (finger) B with the second irradiation light having the second wavelength irradiated by thesecond light emitter 12 and outputs a first light reception signal. Thus, in the present embodiment, thefirst light emitter 11 and thefirst light receiver 13, and thesecond light emitter 12 and thesecond light receiver 14 correspond to each other, and thefirst light receiver 13 and the second light receiver. 14 uses filters that selectively transmit the first wavelength and the second wavelength, respectively.

図５が示すように、制御部２０は、制御回路２１と、駆動回路２２と、受光回路２３と、信号処理回路２４と、外部出力回路２５と、を備える。制御回路２１は、検知部１０に電源を供給すると共に駆動回路２２を制御する。駆動回路２２は、第１発光器１１および第２発光器１２を駆動する第１駆動信号および第２駆動信号を生成し、検知部１０の各発光器を駆動する。受光回路２３は、検知部１０の第１受光器１３および第２受光器１４が出力した第１受光信号および第２受光信号を受け取る。信号処理回路２４は、受光回路２３が受け取ったそれぞれの受光信号を後述する方法で信号を処理する。外部出力回路２５は、信号処理回路２４で処理され検出された脈波の数値を、この脈波の数値を利用する外部の装置等に適合するように出力する。制御部２０は、全体として１つのマイコン（マイクロコンピュータ）に構成してもよいし、複数の専用の集積回路に構成してもよい。  As shown in FIG. 5, thecontrol unit 20 includes acontrol circuit 21, adrive circuit 22, alight receiving circuit 23, asignal processing circuit 24, and anexternal output circuit 25. Thecontrol circuit 21 supplies power to thedetection unit 10 and controls thedrive circuit 22. Thedrive circuit 22 generates a first drive signal and a second drive signal that drive thefirst light emitter 11 and thesecond light emitter 12, and drives each light emitter of thedetection unit 10. Thelight receiving circuit 23 receives the first light receiving signal and the second light receiving signal output from thefirst light receiver 13 and thesecond light receiver 14 of thedetection unit 10. Thesignal processing circuit 24 processes each received light signal received by thelight receiving circuit 23 by a method described later. Theexternal output circuit 25 outputs the pulse wave value processed and detected by thesignal processing circuit 24 so as to be compatible with an external device or the like using the pulse wave value. Thecontrol unit 20 may be configured as a single microcomputer (microcomputer) as a whole, or may be configured as a plurality of dedicated integrated circuits.

図６が示すように、信号処理回路２４は、Ａ／Ｄ変換回路２４３と、演算回路２４２と、フィルタ回路２４１とを備える。Ａ／Ｄ変換回路２４３は、受光回路２３から第１受光信号と第２受光信号をそれぞれ受け取るため２つのＡ／Ｄ変換回路を有する。演算回路２４２は、Ａ／Ｄ変換回路２４３によりアナログ値からデジタル値に変換された第１受光信号と第２受光信号を入力されて、その２つの受光信号から比（強度比）を計算して求める。フィルタ回路２４１は、デジタルフィルタを有し、ノイズを除去した後に外部出力回路２５に渡す。信号処理回路２４が機能することで、心拍による脈動由来の振幅信号が得られる。  As shown in FIG. 6, thesignal processing circuit 24 includes an A /D conversion circuit 243, anarithmetic circuit 242, and afilter circuit 241. The A /D conversion circuit 243 has two A / D conversion circuits for receiving the first light reception signal and the second light reception signal from thelight reception circuit 23, respectively. Thearithmetic circuit 242 receives the first received light signal and the second received light signal converted from analog values to digital values by the A /D conversion circuit 243, and calculates a ratio (intensity ratio) from the two received light signals. Ask. Thefilter circuit 241 has a digital filter, removes noise, and passes it to theexternal output circuit 25. Thesignal processing circuit 24 functions to obtain an amplitude signal derived from pulsation due to heartbeat.

図７および図８を参照して、脈波検出装置１００の信号処理回路２４における信号の処理の方法を中心に説明する。なお、フローチャートにおけるＳはステップを意味する。制御部２０の制御回路２１は、Ｓ１００において、駆動回路２２を介して第１駆動信号および第２駆動信号を送り、第１発光器１１および第２発光器１２を発光させる。図８（Ａ）および（Ｂ）のグラフ示すように、第１発光器１１は、第１波長の出力光を発光し続け、第２発光器１２は、第２波長の出力光を発光し続ける。第１波長は、動脈内に存するヘモグロビンの変動である脈波を検出するために適した波長なので、第１受光器１３の受光信号は、図８（Ｃ）が示すように、心拍数の周波数成分が優勢な周波数を含む波形を有する。一方、第２波長は、第１波長とはわずかに異なる波長なので、図８（Ｅ）が示すように、心拍数の周波数成分も含むが他の体の動きの周波数成分が優勢な周波数（たとえば、脈波の周波数より小さい呼吸の周波数）を含む波形を有する。  With reference to FIG. 7 and FIG. 8, the signal processing method in thesignal processing circuit 24 of the pulsewave detection device 100 will be mainly described. In the flowchart, S means a step. In S100, thecontrol circuit 21 of thecontrol unit 20 sends the first drive signal and the second drive signal via thedrive circuit 22 to cause thefirst light emitter 11 and thesecond light emitter 12 to emit light. As shown in the graphs of FIGS. 8A and 8B, thefirst light emitter 11 continues to emit output light of the first wavelength, and thesecond light emitter 12 continues to emit output light of the second wavelength. . Since the first wavelength is a wavelength suitable for detecting a pulse wave that is a fluctuation of hemoglobin existing in the artery, the received light signal of thefirst light receiver 13 is a frequency of the heart rate as shown in FIG. The component has a waveform containing the dominant frequency. On the other hand, since the second wavelength is slightly different from the first wavelength, as shown in FIG. 8E, the frequency component including the heart rate frequency component but the frequency component of the other body movement is dominant (for example, , A respiration frequency smaller than the pulse wave frequency).

信号処理回路２４は、Ｓ１０２において受光回路２３に入力された第１受光信号を、図８（Ｄ）が示すようにサンプリングし、Ｓ１０４において受光回路２３に入力された第２受光信号を、図８（Ｆ）が示すようにサンプリングする。そして、信号処理回路２４は、Ｓ１０６において、第１受光信号および第２受光信号のサンプリングされた値を基に、第１受光信号および第２受光信号の比（強度比）を算出する。信号処理回路２４は、Ｓ１０８において、Ｍ個の強度比が算出されたか否かを検査し、Ｍ個の強度比を算出するまでサンプリングを繰り返す。なお、Ｍ個とは、脈波を推定するために必要な数であり、推定方法により、また求められる精度や算出時間などにより適宜定められる。また、推定方法は、上述した高速フーリエ変換に限られるものではなく、四則演算のみで推定してもよい。Ｍ個の強度比が算出されたされた場合、信号処理回路２４は、Ｓ１１０において、Ｍ個の強度比が示す第１波長の周波数成分から第２波長の周波数成分を相殺して、心拍数（脈波）の周波数成分のみを検出する。信号処理回路２４は、Ｓ１１２において、検出された心拍数を外部へ出力する。  Thesignal processing circuit 24 samples the first light receiving signal input to thelight receiving circuit 23 in S102 as shown in FIG. 8D, and the second light receiving signal input to thelight receiving circuit 23 in S104 is changed to FIG. Sample as shown in (F). In S106, thesignal processing circuit 24 calculates a ratio (intensity ratio) between the first light reception signal and the second light reception signal based on the sampled values of the first light reception signal and the second light reception signal. In S108, thesignal processing circuit 24 checks whether or not M intensity ratios have been calculated, and repeats sampling until the M intensity ratios are calculated. Note that the number M is a number necessary for estimating a pulse wave, and is appropriately determined by an estimation method, required accuracy, calculation time, and the like. Further, the estimation method is not limited to the above-described fast Fourier transform, and may be estimated only by four arithmetic operations. When the M intensity ratios are calculated, thesignal processing circuit 24 cancels the frequency components of the second wavelength from the frequency components of the first wavelength indicated by the M intensity ratios in S110, and the heart rate ( Only the frequency component of the pulse wave is detected. In S112, thesignal processing circuit 24 outputs the detected heart rate to the outside.

このように、脈波検出装置１００は、第１波長の第１照射光に由来する第１受光信号の強度と、第２波長の第２照射光に由来する第２受光信号の強度に基づき、両者を比較することによって、心拍による動きである脈波の周波数を検出する。なお、上述したように、第１波長の第１照射光および第２波長の第２照射光は近赤外光である。これによれば、ヘモグロビンと水に対する吸光率が互いに異なる２つの波長の近赤外光を照射し、その反射光を分析することで、体の動きによる影響が少なくなり、精度良く脈波を検出する光学式の脈波検出装置１００を提供できる。また、第１波長は、好ましくは８４０〜９００ｎｍであり、第２波長は、好ましくは７４０〜８３０ｎｍである。発明者らが行った実験結果により、近赤外光の中でもこれらの波長を使用することで、より精度良く脈波を検出することができる。  Thus, the pulsewave detection device 100 is based on the intensity of the first light reception signal derived from the first irradiation light of the first wavelength and the intensity of the second light reception signal derived from the second irradiation light of the second wavelength. By comparing the two, the frequency of the pulse wave, which is a movement caused by a heartbeat, is detected. As described above, the first irradiation light having the first wavelength and the second irradiation light having the second wavelength are near-infrared light. According to this, by irradiating two wavelengths of near-infrared light with different absorption rates for hemoglobin and water, and analyzing the reflected light, the influence of the movement of the body is reduced, and the pulse wave is detected accurately. The optical pulsewave detection device 100 can be provided. The first wavelength is preferably 840 to 900 nm, and the second wavelength is preferably 740 to 830 nm. According to the results of experiments conducted by the inventors, pulse waves can be detected with higher accuracy by using these wavelengths in near-infrared light.

さらに、上述したように、実験において、最も際立った差を示しＳ／Ｎ比においても最も高い値を有した第１波長が８７０ｎｍで第２波長が８００ｎｍの組合せの場合、半値幅を考慮して、第１波長が８５０ｎｍ〜８９０ｎｍ程度であり、第２波長が７８０ｎｍ〜８２０ｎｍ程度であってもよい。さらに、Ｓ／Ｎ比においても２番目に高い値を有した第１波長が８７０ｎｍで第２波長が７５０ｎｍの組合せの場合、半値幅を考慮して、第１波長が８５０ｎｍ〜８９０ｎｍ程度であり、第２波長が７３０ｎｍ〜７７０ｎｍ程度であってもよい。そうすると、第１波長が８５０ｎｍ〜８９０ｎｍ程度であり、第２波長が７３０ｎｍ〜８２０ｎｍ程度であれば、体の動きによる影響が少なくなり、精度良く脈波を検出できると言える。  Furthermore, as described above, in the experiment, when the combination of thefirst wavelength 870 nm and thesecond wavelength 800 nm that showed the most remarkable difference and had the highest value in the S / N ratio, the half-value width was considered. The first wavelength may be about 850 nm to 890 nm, and the second wavelength may be about 780 nm to 820 nm. Furthermore, when the first wavelength having the second highest value in the S / N ratio is 870 nm and the second wavelength is 750 nm, the first wavelength is about 850 nm to 890 nm in consideration of the half width. The second wavelength may be about 730 nm to 770 nm. Then, if the first wavelength is about 850 nm to 890 nm and the second wavelength is about 730 nm to 820 nm, it can be said that the influence of the movement of the body is reduced and the pulse wave can be detected with high accuracy.

＜第二実施例＞
図９〜図１３を参照して、本実施例における脈波検出装置１００Ａを説明する。なお、重複記載を避けるために、上記実施例と同じ構成要素には同じ符号を付し、上記実施例とことなる部分を中心に説明する。<Second Example>
With reference to FIGS. 9-13, the pulse-wave detection apparatus 100A in a present Example is demonstrated. In addition, in order to avoid duplication description, the same code | symbol is attached | subjected to the same component as the said Example, and it demonstrates centering on the part different from the said Example.

図９に示すように、脈波検出装置１００Ａの検知部１０Ａは、第１波長の第１照射光を照射する第１発光器１１と、第２波長の第２照射光を照射する第２発光器１２と、第１照射光および第２照射光が反射された第１反射光および第２反射光を受光し、受光信号を出力する受光器１３Ａ（または１４Ａ）と、を備える。  As illustrated in FIG. 9, thedetection unit 10A of the pulsewave detection device 100A includes afirst light emitter 11 that emits first irradiation light having a first wavelength and a second light emission that emits second irradiation light having a second wavelength. And alight receiver 13A (or 14A) that receives the first reflected light and the second reflected light reflected from the first irradiation light and the second irradiation light and outputs a light reception signal.

第１発光器１１および第２発光器１２は、制御部２０Ａと信号線で接続され、プリント配線基板１９上に配置された投光回路部品１７により実際に駆動されて、所定の波長で発光する。受光器１３Ａは、反射して受光窓１６を通って戻ってきた反射光を受光する。受光器１３Ａは、受光した反射光を復調した電気信号を受光回路部品１８に渡す。受光回路部品１８は信号線により制御部２０Ａと接続されており、受光器１３Ａが復調した電気信号は、制御部２０Ａに渡される。  Thefirst light emitter 11 and thesecond light emitter 12 are connected to thecontrol unit 20A through a signal line, and are actually driven by the light projectingcircuit component 17 disposed on the printedwiring board 19 to emit light at a predetermined wavelength. . Thelight receiver 13 </ b> A receives the reflected light that has been reflected and returned through thelight receiving window 16. Thelight receiver 13 </ b> A passes an electric signal obtained by demodulating the received reflected light to the lightreceiving circuit component 18. The lightreceiving circuit component 18 is connected to thecontrol unit 20A by a signal line, and the electric signal demodulated by thelight receiver 13A is passed to thecontrol unit 20A.

受光器１３Ａは、第１発光器１１が照射した第１波長の第１照射光が反射された第１反射光を受光すると共に、第２発光器１２が照射した第２波長の第２照射光が反射された第１反射光を受光し、受光信号を出力する。このように、本実施では、第１発光器１１と第２発光器１２の２つの発光器に対して１つの受光器１３Ａを備えるため、受光器１３Ａは、第１波長の光と第２波長の光の両方を受光できる受光範囲を有するものである。  Thelight receiver 13A receives the first reflected light reflected by the first irradiation light having the first wavelength irradiated by thefirst light emitter 11, and the second irradiation light having the second wavelength irradiated by thesecond light emitter 12. The first reflected light is reflected and a light reception signal is output. As described above, in the present embodiment, since thesingle light receiver 13A is provided for the two light emitters of thefirst light emitter 11 and thesecond light emitter 12, thelight receiver 13A has the first wavelength and the second wavelength. It has a light receiving range that can receive both of the light.

図１０に示すように、制御部２０Ａは、制御回路２１Ａと、駆動回路２２と、受光回路２３Ａと、信号処理回路２４Ａと、外部出力回路２５と、を備える。制御回路２１Ａは、後述する方法により駆動回路２２を駆動する。受光回路２３Ａは、受光器１３Ａが出力した受光信号を受け取る。信号処理回路２４Ａは、受光回路２３Ａが受け取った受光信号を後述する方法で信号を処理する。  As shown in FIG. 10, thecontrol unit 20A includes a control circuit 21A, adrive circuit 22, alight receiving circuit 23A, asignal processing circuit 24A, and anexternal output circuit 25. The control circuit 21A drives thedrive circuit 22 by a method described later. Thelight receiving circuit 23A receives the light reception signal output from thelight receiver 13A. Thesignal processing circuit 24A processes the received light signal received by thelight receiving circuit 23A by a method described later.

図１１が示すように、信号処理回路２４Ａは、Ａ／Ｄ変換回路２４３Ａと、演算回路２４２Ａと、フィルタ回路２４１とを備える。Ａ／Ｄ変換回路２４３Ａは、受光回路２３Ａから受光信号を受け取る１つのＡ／Ｄ変換回路を有する。演算回路２４２Ａは、Ａ／Ｄ変換回路２４３Ａによりアナログ値からデジタル値に変換された受光信号を入力されて、第１波長の第１照射光が反射された第１反射光に由来する受光信号と、第２波長の第２照射光が反射された第２反射光に由来する受光信号とから比（強度比）を計算して求める。  As illustrated in FIG. 11, thesignal processing circuit 24A includes an A / D conversion circuit 243A, anarithmetic circuit 242A, and afilter circuit 241. The A / D conversion circuit 243A has one A / D conversion circuit that receives a light reception signal from thelight reception circuit 23A. Thearithmetic circuit 242A receives the light reception signal converted from the analog value into the digital value by the A / D conversion circuit 243A, and receives the light reception signal derived from the first reflected light from which the first irradiation light having the first wavelength is reflected. The ratio (intensity ratio) is calculated and obtained from the received light signal derived from the second reflected light from which the second irradiation light having the second wavelength is reflected.

図１２および図１３を参照して、脈波検出装置１００Ａにおける第１発光器１１および第２発光器１２の発光方法と信号処理回路２４Ａにおける信号の処理の方法を中心に説明する。制御回路２１Ａは、Ｓ２００において、駆動回路２２を介して第１駆動信号を送り、図１３（Ａ）のグラフが示すように、第１発光器１１を例えば０．２〜０．３ｍｓの間発光させた後オフにするように駆動する。第１発光器１１が発光すると、その間に受光器１３Ａは、図１３（Ｃ）に示すように第１反射光を受光する。信号処理回路２４Ａは、Ｓ２０２において受光回路２３Ａに入力された受光信号を第１受光信号として、図１３（Ｄ）が示すようにサンプリングする。  With reference to FIG. 12 and FIG. 13, the light emission method of thefirst light emitter 11 and thesecond light emitter 12 in the pulsewave detection device 100A and the signal processing method in thesignal processing circuit 24A will be mainly described. In S200, the control circuit 21A sends a first drive signal via thedrive circuit 22, and as shown in the graph of FIG. 13A, thefirst light emitter 11 emits light for 0.2 to 0.3 ms, for example. Then, it is driven to turn off. When thefirst light emitter 11 emits light, thelight receiver 13A receives the first reflected light as shown in FIG. Thesignal processing circuit 24A samples the light reception signal input to thelight reception circuit 23A in S202 as a first light reception signal as shown in FIG.

制御回路２１Ａは、第１発光器１１の発光をオフした後、Ｓ２０４において、第２発光器１２を同じ時間、図１３（Ｂ）のグラフが示すように発光させる。第２発光器１２が発光すると、その間に受光器１３Ａは、図１３（Ｅ）に示すように第２反射光を受光する。信号処理回路２４Ａは、Ｓ２０６において、受光回路２３Ａに入力された受光信号を第２受光信号として、図１３（Ｆ）が示すようにサンプリングする。信号処理回路２４Ａは、Ｓ２０８において、Ｎ個のサンプリング値が得られたか否かを検査し、Ｎ個のサンプリング値が得られるまでサンプリングを繰り返す。なお、Ｎ個は、第１受光信号および第２受光信号の値の積算値を得るためにサンプリングする回数である。たとえば、第１発光器１１および第２発光器１２を０．２５ｍｓの周期で交互に間欠的に発光させ、各発光器の発光１回につき、1回サンプリングを行う。Ｎ個が２００個の場合とすると、サンプリングされた２００回の受光信号を加算して積算値を算出する。つまり、５０ｍｓの周期で積算値が発光器ごとに得られることになる。  After the light emission of thefirst light emitter 11 is turned off, the control circuit 21A causes thesecond light emitter 12 to emit light for the same period of time as shown in the graph of FIG. 13B in S204. When thesecond light emitter 12 emits light, thelight receiver 13A receives the second reflected light as shown in FIG. In S206, thesignal processing circuit 24A samples the light reception signal input to thelight reception circuit 23A as the second light reception signal as shown in FIG. In S208, thesignal processing circuit 24A checks whether or not N sampling values are obtained, and repeats sampling until N sampling values are obtained. N is the number of times of sampling to obtain an integrated value of the values of the first light receiving signal and the second light receiving signal. For example, thefirst light emitter 11 and thesecond light emitter 12 are caused to emit light alternately and intermittently at a cycle of 0.25 ms, and sampling is performed once for each light emission of each light emitter. If N is 200, the sampled 200 received light signals are added to calculate the integrated value. That is, an integrated value is obtained for each light emitter at a period of 50 ms.

Ｎ個のサンプリング値が得られた場合、信号処理回路２４Ａは、Ｓ２１０において、サンプリングされたＮ個の第１受光信号の値を積算し、Ｓ２１２において、サンプリングされたＮ個の第２受光信号の値を積算する。そして、信号処理回路２４Ａは、Ｓ２１４において、両方の積算値を基に両者の比（強度比）を算出する。  When N sampling values are obtained, thesignal processing circuit 24A integrates the values of the sampled N first light reception signals in S210, and in S212, the sampled N second light reception signals. Accumulate values. Then, in S214, thesignal processing circuit 24A calculates a ratio (intensity ratio) between the two based on both integrated values.

信号処理回路２４Ａは、Ｓ２１６において、第１受光信号の値の積算値と第２受光信号の値の積算値の比（強度比）がＭ個算出されたか否かを検査し、Ｍ個の強度比が得られるまでサンプリングを繰り返す。なお、Ｍ個とは、脈波を推定するために必要な数である。Ｍ個の強度比が算出されたされた場合、信号処理回路２４Ａは、Ｓ２１８において、Ｍ個の強度比が示す第１波長の周波数成分から第２波長の周波数成分を相殺して、心拍数（脈波）の周波数成分のみを検出する。信号処理回路２４Ａは、Ｓ２２０において、検出された心拍数を外部へ出力する。  In S216, thesignal processing circuit 24A checks whether or not the ratio (intensity ratio) of the integrated value of the first received light signal value and the integrated value of the second received light signal value has been calculated in S216. Repeat sampling until the ratio is obtained. Note that M is the number necessary to estimate the pulse wave. When the M intensity ratios are calculated, thesignal processing circuit 24A cancels the frequency components of the second wavelength from the frequency components of the first wavelength indicated by the M intensity ratios in S218, and the heart rate ( Only the frequency component of the pulse wave is detected. In S220, thesignal processing circuit 24A outputs the detected heart rate to the outside.

このように、本実施例における脈波検出装置１００Ａは、第１発光器１１と第２発光器１２は、交互に第１照射光と第２照射光を照射し、第１発光器１１が発光したタイミングで受光器１３Ａが受光した受光信号を第１受光信号とみなし、第２発光器１２が発光したタイミングで受光器１３Ａが受光した受光信号を第２受光信号とみなす。受光器１３Ａは、上記実施例と異なり、１つの受光素子から構成されている。これによれば、受光器の数を削減することで脈波検出装置１００Ａのコストを安くすることができる。  Thus, in the pulsewave detection device 100A in the present embodiment, thefirst light emitter 11 and thesecond light emitter 12 alternately emit the first irradiation light and the second irradiation light, and thefirst light emitter 11 emits light. The light reception signal received by thelight receiver 13A at the timing received is regarded as the first light reception signal, and the light reception signal received by thelight receiver 13A at the timing emitted by thesecond light emitter 12 is regarded as the second light reception signal. Unlike the above embodiment, thelight receiver 13A is composed of one light receiving element. According to this, the cost of the pulsewave detection device 100A can be reduced by reducing the number of light receivers.

なお、本実施例の脈波検出装置１００Ａは、上記実施例の脈波検出装置１００に比べ、Ｍ個の強度比を取得するのに時間がかかるが、第１波長の第１照射光に由来する第１受光信号の強度と、第２波長の第２照射光に由来する第２受光信号の強度に基づき強度比が求められるので、同様に心拍による動きである脈波の周波数を検出することができる。  Note that the pulsewave detection device 100A of the present embodiment takes more time to acquire M intensity ratios than the pulsewave detection device 100 of the above embodiment, but is derived from the first irradiation light of the first wavelength. Since the intensity ratio is obtained based on the intensity of the first received light signal and the intensity of the second received light signal derived from the second irradiation light having the second wavelength, the frequency of the pulse wave, which is the movement caused by the heartbeat, is detected in the same manner. Can do.

なお、本発明は、例示した実施例に限定するものではなく、特許請求の範囲の各項に記載された内容から逸脱しない範囲の構成による実施が可能である。すなわち、本発明は、主に特定の実施形態に関して特に図示され、かつ説明されているが、本発明の技術的思想および目的の範囲から逸脱することなく、以上述べた実施形態に対し、数量、その他の詳細な構成において、当業者が様々な変形を加えることができるものである。  In addition, this invention is not limited to the illustrated Example, The implementation by the structure of the range which does not deviate from the content described in each item of a claim is possible. That is, although the present invention has been particularly illustrated and described with respect to particular embodiments, it should be understood that the present invention has been described in terms of quantity, quantity, and amount without departing from the scope and spirit of the present invention. In other detailed configurations, various modifications can be made by those skilled in the art.

１００ 脈波検出装置
１０ 検知部
１１ 第１発光器
１２ 第２発光器
１３ 第１受光器
１４ 第２受光器
１５ 投光窓
１６ 受光窓
１７ 投光回路部品
１８ 受光回路部品
１９ プリント配線基板
２０ 制御部
２１ 制御回路
２２ 駆動回路
２３ 受光回路
２４ 信号処理回路
２４１ フィルタ回路
２４２ 演算回路
２４３ Ａ／Ｄ変換回路
２５ 外部出力回路
Ｂ 生体（指）DESCRIPTION OFSYMBOLS 100 Pulsewave detection apparatus 10Detection part 111st light emitter 122nd light emitter 131st light receiver 142nd light receiver 15Light projection window 16Light reception window 17 Lightprojection circuit component 18 Lightreception circuit component 19 Printedwiring board 20Control Unit 21Control circuit 22Drive circuit 23Light receiving circuit 24Signal processing circuit 241Filter circuit 242 Arithmetic circuit 243 A /D conversion circuit 25 External output circuit B Living body (finger)

Claims (3)

Translated fromJapanese

生体に対して第１波長の第１照射光を照射する第１発光器と、
生体に対して第２波長の第２照射光を照射する第２発光器と、
前記第１照射光が前記生体によって反射された第１反射光を受光し、第１受光信号を出力する第１受光器と、
前記第２照射光が前記生体によって反射された第２反射光を受光し、第２受光信号を出力する第２受光器と、
前記第１受光信号の強度と前記第２受光信号の強度に基づいて脈波の周波数を検出する制御部と、
を備え、
前記第１波長の前記第１照射光および前記第２波長の前記第２照射光は近赤外光である、
脈波検出装置。A first light emitter for irradiating a living body with a first irradiation light having a first wavelength;
A second light emitter for irradiating the living body with the second irradiation light having the second wavelength;
A first light receiver that receives the first reflected light reflected by the living body and outputs a first received light signal;
A second light receiver for receiving the second reflected light reflected by the living body and outputting a second light receiving signal;
A controller that detects the frequency of the pulse wave based on the intensity of the first light receiving signal and the intensity of the second light receiving signal;
With
The first irradiation light of the first wavelength and the second irradiation light of the second wavelength are near infrared light,
Pulse wave detector. 前記第１波長は８３５〜９１０ｎｍであり、前記第２波長は７４０〜８３０ｎｍであることを特徴とする請求項１に記載の脈波検出装置。  2. The pulse wave detection device according to claim 1, wherein the first wavelength is 835 to 910 nm, and the second wavelength is 740 to 830 nm. 前記第１発光器と前記第２発光器は交互に前記第１照射光と前記第２照射光を照射し、
前記第１受光器と前記第２受光器は１つの受光素子からなることを特徴とする請求項１または２に記載の脈波検出装置。The first light emitter and the second light emitter alternately emit the first irradiation light and the second irradiation light,
The pulse wave detection device according to claim 1, wherein the first light receiver and the second light receiver include one light receiving element.

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