JP2009005721A - Pulse wave measuring method and pulse wave measuring apparatus used for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulse wave measuring method and a pulse wave measuring apparatus of a simple configuration for highly accurately measuring pulse waves by surely reducing the influence of body movements by the apparatus. <P>SOLUTION: Polarized irradiation light is emitted in the state without the body movements; a first polarized light component in a direction which is one of polarization directions same as and orthogonal to the irradiation light and a second polarized light component in the other direction in the reflected light are separated and detected; first signals and second signals respectively corresponding to the first and second polarized light components are separated into pulse wave signals and non pulse wave signals, and the ratio of the pulse wave signals of the first signals to the pulse wave signals of the second signals and the ratio of the non pulse wave signals of the first signals to the non pulse wave signals of the second signals are acquired. The irradiation light is emitted in the state with possibility of the body movements, a third polarized light component in a direction which is one of the polarization directions same as and orthogonal to the irradiation light and a fourth polarized light component in the other direction in the reflected light are separated and detected, two signals respectively corresponding to the third and fourth polarized light components are computed using the two ratios and the pulse wave signals are extracted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for measuring a pulse wave of a living body by irradiating the living body with light and detecting reflected light reflected by the living body.

  The principle of the pulse wave measuring device uses that part of the light irradiated to the living body is absorbed by hemoglobin in the blood. That is, the living body is irradiated with light having a wavelength that is absorbed by hemoglobin, and the reflected light from the living body is detected by an optical sensor and converted into an electrical signal. This electric signal includes a signal corresponding to the amount of red blood cells in the blood vessel, and the signal intensity changes in synchronization with the pulsation. Of the electrical signal output from the optical sensor, the component that changes in synchronization with the pulsation is the pulse wave signal. However, the reflected light from the living body includes light reflected by the skin surface and living tissue in the vicinity of the surface, and these light does not include a pulse wave signal. In addition, if the wavelength of irradiated light is 400-1000 nm, since it is easy to be absorbed by hemoglobin and absorption on the skin surface is comparatively small, it is known that it is suitable for pulse wave measurement.

  When the living body moves during the measurement, the reflected light intensity is changed by changing the relative position between the light source for irradiation and the optical sensor and the living body. Of the electric signal output from the optical sensor, the component that changes due to the movement (body movement) of the living body is the body movement signal. When the living body moves during measurement in this way, the electrical signal output from the optical sensor includes not only the pulse wave signal but also the body motion signal, so that the pulse wave signal cannot be accurately measured. .

  In order to reduce the influence of this body movement, the living body is irradiated with a plurality of irradiation lights having different wavelengths, the reflected light is separated for each wavelength and detected by an optical sensor, and the difference between output signals from the optical sensor is calculated. A technique for extracting a pulse wave signal by detection is disclosed (for example, see Patent Documents 1 and 2). However, the methods described in Patent Documents 1 and 2 have a problem in that a plurality of light sources and optical sensors are required in order to use a plurality of irradiation lights having different wavelengths, resulting in a complicated apparatus configuration.

Therefore, as a method of reducing the influence of body movement with a device having a simple configuration, the living body is irradiated with polarized light, and the reflected light from the living body is changed to the first polarized light whose vibration direction of the electric vector is the same as the above polarized light. A method has been proposed in which the vibration direction of the electric vector is detected separately from the second polarized light whose direction is perpendicular to the polarized light (see, for example, Patent Document 3). In Patent Document 3, the output of at least one of the first polarization and the second polarization is reduced so that the difference between the body motion signals in the output signals of the first polarization and the second polarization detected by the optical sensor becomes small. A technique is disclosed in which heartbeat information of a living body is obtained by processing a signal and calculating a difference or quotient of data corresponding to output signals of the first polarization and the second polarization.
JP 60-135029 A Japanese National Patent Publication No. 5-506802 Japanese Patent Laid-Open No. 11-128177

  In Patent Document 3, the output of at least one of the first polarization and the second polarization is reduced so that the difference between the body motion signals in the output signals of the first polarization and the second polarization detected by the optical sensor becomes small. As an example of a method of processing the signal, a body motion in the output signal of the second polarization is obtained by obtaining a ratio K of the body motion signal in the output signal of the first polarization and the body motion signal in the output signal of the second polarization. It is disclosed that the signal is multiplied by K.

  However, in Patent Document 3, the body motion signal in the output signal of the first polarization and the body motion signal in the output signal of the second polarization are extracted from the electrical signal output from the optical sensor. It is not disclosed whether to do it.

  In view of the above-described conventional problems, the present invention provides a pulse wave measuring method and a pulse wave measuring apparatus capable of measuring a pulse wave with high accuracy by reliably reducing the influence of body movement with an apparatus having a simple configuration. The purpose is to provide.

In order to solve the above-described conventional problems, the pulse wave measuring method of the present invention includes (A) a step of irradiating the measurement site with irradiation light that is polarized light while the measurement site of the living body that is the measurement target is not moving. ,
(B) Of the reflected light reflected at the measurement site with the irradiation of the irradiation light in the step A with no movement at the measurement site, the polarization direction is the same as that of the irradiation light and the orthogonal polarization direction. A step of separating and detecting a first polarization component that is one of the polarization directions and a second polarization component that is a polarization direction orthogonal to the first polarization component;
(C) For each of the first signal corresponding to the first polarization component and the second signal corresponding to the second polarization component detected in the step B, the pulse wave signal and the pulse wave signal are excluded. Separating the signal into a non-pulse wave signal,
(D) Pulse wave signal information related to a ratio between the pulse wave signal of the first signal and the pulse wave signal of the second signal, and non-pulse wave signals of the first signal and non-pulse signals of the second signal Obtaining non-pulse wave signal information relating to a ratio with a pulse wave signal;
(E) a step of irradiating the measurement site with the irradiation light in a state where the measurement site of the living body can be moved;
(F) Of the reflected light reflected at the measurement site in accordance with the irradiation of the irradiation light in the step E in a state where the measurement site can move, the same polarization direction as the irradiation light and a polarization direction orthogonal to the irradiation light A step of separating and detecting a third polarization component having one of the polarization directions and a fourth polarization component having a polarization direction orthogonal to the third polarization component; and (G) the step Using the pulse wave signal information and the non-pulse wave signal information acquired in D, corresponding to the third signal and the fourth polarization component corresponding to the third polarization component detected in the step F A step of extracting a pulse wave signal of the living body in a state in which there is a movement in the measurement site by calculating the fourth signal.

The pulse wave measuring device of the present invention is a device used for the pulse wave measuring method,
A light source that emits the irradiation light that irradiates the measurement site;
A polarizer for limiting the polarization direction of the irradiation light;
Of the reflected light reflected at the measurement site, a polarization beam splitter that separates a component in the same polarization direction as the irradiation light and a component in the polarization direction orthogonal to the irradiation light,
A first optical sensor that detects any one polarization component of the same polarization direction component and the orthogonal polarization direction component of the irradiation light;
A second optical sensor for detecting a component in the polarization direction orthogonal to the polarization direction detected by the first optical sensor;
A first low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the first photosensor;
A second low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the second photosensor;
A first high-pass filter that transmits a frequency component included in a frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the first photosensor;
A second high-pass filter that transmits a frequency component included in the frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the second photosensor;
A first divider for dividing the output signal of the second low-pass filter by the output signal of the first low-pass filter;
A second divider for dividing the output signal of the second high-pass filter by the output signal of the first high-pass filter;
A variable gain amplifier that amplifies an output signal of one of the first photosensor and the second photosensor;
A differential amplifier for amplifying a difference between an output signal of the other of the first optical sensor and the second optical sensor and an output signal of the variable gain amplifier; and an output signal of the first divider. An amplification factor controller for controlling the amplification factor of the variable gain amplifier is provided.

Another pulse wave measuring device of the present invention is a device used for the pulse wave measuring method.
A light source that emits the irradiation light that irradiates the measurement site;
A first polarizer for limiting a polarization direction of the irradiation light;
An optical modulator that modulates a polarization direction of the irradiation light transmitted through the first polarizer;
A modulation signal for operating the optical modulator such that the polarization direction of the irradiation light is alternately switched in two directions orthogonal to each other, and a modulation signal having a frequency higher than the frequency band of the pulse wave signal is transmitted to the optical modulator. A signal generator,
A second polarizer that limits the polarization direction of the reflected light reflected at the measurement site;
An optical sensor for detecting the reflected light transmitted through the second polarizer;
A demultiplexer that separates an output signal of the optical sensor into an in-phase component and an anti-phase component of the modulation signal;
A third low-pass filter that transmits only a frequency component lower than the modulation signal from a signal corresponding to one of the in-phase component and the anti-phase component output from the demultiplexer;
A fourth low-pass filter that transmits only a frequency component lower than the modulation signal from a signal corresponding to the other component of the in-phase component and the anti-phase component output from the demultiplexer;
A first low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the third low-pass filter;
A second low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the fourth low-pass filter;
A first high-pass filter that transmits a frequency component included in a frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from an output signal of the third low-pass filter;
A second high-pass filter that transmits a frequency component included in the frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the fourth low-pass filter;
A first divider for dividing the output signal of the second low-pass filter by the output signal of the first low-pass filter;
A second divider for dividing the output signal of the second high-pass filter by the output signal of the first high-pass filter;
A variable gain amplifier that amplifies an output signal of any one of the third low-pass filter and the fourth low-pass filter;
A differential amplifier that amplifies a difference between the output signal of the other of the third low-pass filter and the fourth low-pass filter and the output signal of the variable gain amplifier; and an output signal of the first divider An amplification factor controller for controlling the amplification factor of the variable gain amplifier is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the influence of a body motion can be reliably reduced with the apparatus of simple structure, and a pulse wave can be measured with high precision.

The pulse wave measuring method according to the present invention includes (A) a step of irradiating the measurement site with irradiation light that is polarized light in a state where there is no movement in the measurement site of the living body to be measured,
(B) Of the reflected light reflected at the measurement site with the irradiation of the irradiation light in the step A with no movement at the measurement site, the polarization direction is the same as that of the irradiation light and the orthogonal polarization direction. A step of separating and detecting a first polarization component that is one of the polarization directions and a second polarization component that is a polarization direction orthogonal to the first polarization component;
(C) For each of the first signal corresponding to the first polarization component and the second signal corresponding to the second polarization component detected in the step B, the pulse wave signal and the pulse wave signal are excluded. Separating the signal into a non-pulse wave signal,
(D) Pulse wave signal information related to a ratio between the pulse wave signal of the first signal and the pulse wave signal of the second signal, and non-pulse wave signals of the first signal and non-pulse signals of the second signal Obtaining non-pulse wave signal information relating to a ratio with a pulse wave signal;
(E) a step of irradiating the measurement site with the irradiation light in a state where the measurement site of the living body can be moved;
(F) Of the reflected light reflected at the measurement site in accordance with the irradiation of the irradiation light in the step E in a state where the measurement site can move, the same polarization direction as the irradiation light and a polarization direction orthogonal to the irradiation light A step of separating and detecting a third polarization component having one of the polarization directions and a fourth polarization component having a polarization direction orthogonal to the third polarization component; and (G) the step Using the pulse wave signal information and the non-pulse wave signal information acquired in D, corresponding to the third signal and the fourth polarization component corresponding to the third polarization component detected in the step F A step of extracting a pulse wave signal of the living body in a state in which there is a movement in the measurement site by calculating the fourth signal.

  According to the pulse wave measurement method of the present invention, a pulse wave signal can be extracted with high accuracy by using one kind of illumination light and reducing non-pulse wave signals including body motion signals.

  It is preferable that the wavelength of irradiation light is a wavelength included in a wavelength range of 400 to 1000 nm. If it does in this way, since it is easy to be absorbed by hemoglobin and absorption on the skin surface is comparatively small, it is suitable for pulse wave measurement.

  The reflected light reflected at the measurement site of the living body is incident on the surface of the living body (inside the layer) and the surface reflected light that is reflected without being diffused from the surface of the living body, the surface diffuse reflected light that is diffusely reflected from the surface of the living body There is in-layer diffuse reflection light that is diffused and reflected within the layer and then exits the living body at a position away from the incident position. It is known that the surface reflected light does not include a pulse wave signal but includes only a body motion signal, and the surface diffuse reflection light and the in-layer diffuse reflection light include a pulse wave signal and a body motion signal. Therefore, in the pulse wave measurement method of the present invention, in the steps B and F, out of the reflected light reflected at the measurement site, it enters the living body from the irradiation position of the irradiation light at the measurement site, and It is preferable to detect only reflected light emitted outside the living body at a position away from the irradiation position, that is, only diffuse reflection light within the layer. In this way, the ratio of the body motion signal that is a noise component included in the detected signal is reduced, so that the signal-to-noise ratio (hereinafter abbreviated as SN ratio) can be improved.

  The interval between the irradiation position of the irradiation light and the position where the reflected light is emitted outside the living body is preferably 6 to 12 mm.

  In the pulse wave measurement method of the present invention, for example, in the step D, the value n of the ratio of the pulse wave signal of the first signal and the pulse wave signal of the second signal as the pulse wave signal information, As the non-pulse wave signal information, a value m of the ratio of the non-pulse wave signal of the first signal and the non-pulse wave signal of the second signal is acquired, and in the step G, the third signal is The pulse wave signal of the living body can be extracted by subtracting a signal obtained by multiplying the fourth signal by 1 / m. In the step G, the fourth signal may be subtracted from a signal obtained by multiplying the third signal by m.

  In the pulse wave measuring method of the present invention, (H) Steps A to D are performed using a plurality of the irradiation lights having different polarization directions, and a value n of the ratio of n to m for each of the irradiation lights. A step of calculating / m, and (I) using the result of the calculation in step H, further extracting the irradiation light having the minimum value of n / m from the plurality of irradiation lights, The steps E to G are preferably performed using the irradiation light extracted in the step I. In this way, since the intensity of the detected signal increases, the SN ratio can be further improved.

The pulse wave measuring device of the present invention is a pulse wave measuring device used for the above-described pulse wave measuring method,
A light source that emits the irradiation light that irradiates the measurement site;
A polarizer for limiting the polarization direction of the irradiation light;
Of the reflected light reflected at the measurement site, a polarization beam splitter that separates the same polarization direction component as the irradiation light and the polarization component orthogonal to the irradiation light,
A first optical sensor for detecting a component in one polarization direction among a component in the same polarization direction as the irradiation light and a component in a polarization direction orthogonal to the irradiation light;
A second optical sensor for detecting a component in the polarization direction orthogonal to the component in the polarization direction detected by the first optical sensor;
A first low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the first photosensor;
A second low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the second photosensor;
A first high-pass filter that transmits a frequency component included in a frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the first photosensor;
A second high-pass filter that transmits a frequency component included in the frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the second photosensor;
A first divider for dividing the output signal of the second low-pass filter by the output signal of the first low-pass filter;
A second divider for dividing the output signal of the second high-pass filter by the output signal of the first high-pass filter;
A variable gain amplifier that amplifies an output signal of one of the first photosensor and the second photosensor;
A differential amplifier for amplifying a difference between an output signal of the other of the first optical sensor and the second optical sensor and an output signal of the variable gain amplifier; and an output signal of the first divider An amplification factor controller for controlling the amplification factor of the variable gain amplifier is provided.

  According to the pulse wave measuring apparatus of the present invention, the amplification factor control unit controls the amplification factor of the variable gain amplifier based on the output signal of the first divider, thereby reducing the non-pulse wave signal in the differential amplifier. The pulse wave signal can be measured from the output signal of the differential amplifier.

  The pulse wave measuring apparatus according to the present invention includes a polarizer driving unit that rotates the polarizer, and an arithmetic operation that calculates a value of a ratio between the output signal of the second divider and the output signal of the first divider. And a drive control unit for controlling the polarizer driving unit so that the value is minimized. With such a configuration, since the output signal of the differential amplifier increases, the SN ratio can be improved.

The pulse wave measuring device of the present invention is a pulse wave measuring device used for the above-described pulse wave measuring method,
A light source that emits the irradiation light that irradiates the measurement site;
A first polarizer for limiting a polarization direction of the irradiation light;
An optical modulator that modulates a polarization direction of the irradiation light transmitted through the first polarizer;
A modulation signal for operating the optical modulator such that the polarization direction of the irradiation light is alternately switched in two directions orthogonal to each other, and a modulation signal having a frequency higher than the frequency band of the pulse wave signal is transmitted to the optical modulator. A signal generator,
A second polarizer that limits the polarization direction of the reflected light reflected at the measurement site;
An optical sensor for detecting the reflected light transmitted through the second polarizer;
A demultiplexer that separates an output signal of the optical sensor into an in-phase component and an anti-phase component of the modulation signal;
From the signal corresponding to one of the in-phase component and the anti-phase component output from the demultiplexer, only the frequency component lower than the modulation signal is transmitted and included in the frequency band of the pulse wave signal A third low-pass filter that transmits the transmitted frequency component,
From the signal corresponding to the other of the in-phase component and the anti-phase component output from the demultiplexer, only the frequency component lower than the modulation signal is transmitted and included in the frequency band of the pulse wave signal A fourth low-pass filter that transmits the frequency component;
A first low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the third low-pass filter;
A second low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the fourth low-pass filter;
A first high-pass filter that transmits a frequency component included in a frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from an output signal of the third low-pass filter;
A second high-pass filter that transmits a frequency component included in the frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the fourth low-pass filter;
A first divider for dividing the output signal of the second low-pass filter by the output signal of the first low-pass filter;
A second divider for dividing the output signal of the second high-pass filter by the output signal of the first high-pass filter;
A variable gain amplifier that amplifies an output signal of any one of the third low-pass filter and the fourth low-pass filter;
A differential amplifier that amplifies a difference between the output signal of the other of the third low-pass filter and the fourth low-pass filter and the output signal of the variable gain amplifier; and an output signal of the first divider An amplification factor controller that controls the amplification factor of the variable gain amplifier may be provided.

  Even with such a configuration, the amplification factor control unit controls the amplification factor of the variable gain amplifier based on the output signal of the first divider, thereby reducing the non-pulse wave signal in the differential amplifier. A pulse wave signal can be measured from the output signal of the amplifier.

  Here, an arithmetic unit that calculates a value of a ratio between the output signal of the second divider and the output signal of the first divider, and the signal generator is controlled so that the value is minimized. It is preferable to further include a signal generator control unit. With such a configuration, since the output signal of the differential amplifier increases, the SN ratio can be improved. Moreover, since it is not necessary to mechanically drive the polarizer, the measurement time can be shortened.

  Further, the pulse wave measuring device of the present invention is configured to calculate a value of a ratio between the output signal of the second divider and the output signal of the first divider, and the value exceeds a threshold value. It is preferable to further include a warning output unit that outputs a warning in such a case. The larger the value of the ratio between the output signal of the second divider and the output signal of the first divider, the smaller the output signal of the differential amplifier, so the SN ratio becomes lower. By providing the warning output unit, the user of the pulse wave measurement device has a ratio value between the output signal of the second divider and the output signal of the first divider exceeding the threshold value, and the measurement site It is possible to know that the measurement site needs to be changed because of the inappropriateness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The configuration of the pulse wave measuring apparatus according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view of a pulse wave measurement device 100 according to the present embodiment, and FIG. 2 is a front view of the pulse wave measurement device 100.

  The pulse wave measuring apparatus 100 according to the present embodiment includes an apparatus main body 102 that stores an optical system and an electric system member, and a mounting ring 104. The mounting ring 104 has a hollow cylindrical shape, and, as shown in FIG. 1, a human finger 158 to be a measurement site is inserted into the hollow portion at the time of measurement.

  The apparatus main body 102 is provided with a measurement start switch 106 and a display 146 as a display unit, and the mounting ring 104 is provided with a measurement preparation completion display lamp 108.

  Next, the internal structure of the apparatus main body 102 of the pulse wave measuring apparatus 100 will be described with reference to FIG. FIG. 3 is a block diagram showing an internal configuration of the apparatus main body 102 of the pulse wave measuring apparatus 100.

  As shown in FIG. 3, the apparatus main body 102 includes a light source 112, a polarizer 114, a polarizing beam splitter 118, a first photosensor 120, a second photosensor 122, a first low-pass filter 124, a second Low-pass filter 126, first high-pass filter 128, second high-pass filter 130, first divider 132, second divider 134, variable gain amplifier 136, differential amplifier 138, computer 140, emission light emission A hole 142 and a reflected light incident hole 144 are provided. Here, the computer 140 corresponds to an amplification factor control unit in the present invention.

  The light source 112 includes a semiconductor laser and an optical system that emits light emitted from the semiconductor laser as substantially parallel light, and irradiates the living body 152 with irradiation light 150 having a beam diameter of 1.2 mm and a wavelength of 780 nm. To do. The polarizer 114 has a disk shape and has a function of aligning the polarization direction of the irradiation light 150 emitted from the light source 112 in one direction. In the present embodiment, the polarizer 114 is arranged so that the polarization direction of the irradiation light 150 is aligned with the y direction in FIG. The irradiation light 150 emitted from the light source 112 and transmitted through the polarizer 114 is irradiated to the measurement site of the living body 152 through the irradiation light emission hole 142.

  When the irradiation light 150 irradiated to the living body 152 reaches the living body 152, a part of the irradiation light 150 is reflected by the skin surface, but the rest propagates while diffusing in the living tissue, and is emitted from the living body 152 as reflected light. Here, most of the reflected light emitted from the irradiation position of the irradiation light 150 is the surface reflection light which is a component reflected on the skin surface not including the pulse wave signal, and is diffusely reflected inside the living body including the pulse wave signal. The ratio of surface diffuse reflection light as a component is as small as about 1/1000. On the other hand, the reflected light emitted from a position 6 to 12 mm away from the irradiation position of the irradiation light 150 includes only in-layer diffuse reflection light that is light that propagates while diffusing in the living tissue. The ratio of the pulse wave signal in the in-layer diffuse reflected light is as large as about 1/100 to 1/10.

  By limiting the light receiving angle of the polarization beam splitter 118 by the reflected light incident hole 144, only reflected light emitted from a position 6 to 12 mm away from the irradiation position of the irradiated light 150 passes through the reflected light incident hole 144 and is polarized. The light enters the splitter 118.

  The polarization beam splitter 118 reflects light polarized in the x direction and transmits light polarized in the y direction. Accordingly, of the reflected light from the living body 152, the first reflected light 154, which is a component polarized in the x direction, enters the first optical sensor 120 and is converted into an electrical signal, and the first reflected light 154 is a component polarized in the y direction. The second reflected light 156 enters the second optical sensor 122 and is converted into an electrical signal. That is, the first reflected light 154 has a polarization direction orthogonal to the irradiation light 150, and the second reflected light 156 has the same polarization direction as the irradiation light 150.

  The output signal of the second photosensor 122 is input to the variable gain amplifier 136 and amplified by the computer 140 to a preset amplification factor. The output signal of the first optical sensor 120 and the output signal of the variable gain amplifier 136 are input to the differential amplifier 138. The differential amplifier 138 outputs the difference between the output signal of the first optical sensor 120 and the output signal of the variable gain amplifier 136 as a pulse wave signal. The pulse wave signal output from the differential amplifier 138 is displayed on the display 146.

  Next, a method for setting the gain of the variable gain amplifier 136 will be described with reference to FIG. FIG. 4 is a graph schematically showing an example of output signals of the first photosensor 120, the second photosensor 122, and the differential amplifier 138. In FIG. 4, the vertical axis of each graph is, in order from the top, the output signal So (t) of the first photosensor 120, the output signal Sp (t) of the second photosensor 122, and the output signal of the differential amplifier 138. S (t) is shown, and the horizontal axis shows time t.

  Po (t) is a component of the pulse wave signal in the output signal of the first optical sensor 120, and changes according to the pulsation. Ro (t) is a component (non-pulse wave signal) other than the pulse wave signal in the output signal of the first optical sensor 120, and is constant when there is no body motion, but changes with body motion. Includes signal. Pp (t) is a component of a pulse wave signal in the output signal of the second optical sensor 122, and changes according to the pulsation. Rp (t) is a component (non-pulse wave signal) other than the pulse wave signal in the output signal of the second optical sensor 122, and is constant when there is no body motion, but changes with body motion. Includes signal.

  The output signal So (t) of the first optical sensor 120 and the output signal Sp (t) of the second optical sensor 122 are expressed by the following (Equation 1) and (Equation 2), respectively.

  The relationship between the pulse wave signal Po (t) and Pp (t) is expressed by the following (Equation 3).

  Here, n is a constant.

  Furthermore, the relationship between Ro (t) and Rp (t), which are non-pulse wave signals, is expressed by the following (Equation 4).

  Here, m is a constant.

  Since there is no body motion signal in the state where there is no body motion at the measurement site of the living body, Ro (t) and Rp (t) which are non-pulse wave signals do not include any body motion signal, and Ro and Rp are constants, respectively. And can be expressed as Therefore, the output signal So (t) of the first optical sensor 120, the output signal Sp (t) of the second optical sensor 122, and the non-pulse wave signal Ro (t) when there is no body movement at the measurement site of the living body. ) And Rp (t) are expressed as the following (Equation 5), (Equation 6), and (Equation 7).

  Both the first low-pass filter 124 and the second low-pass filter 126 shown in FIG. 3 have a function of transmitting only a frequency component of 0.03 Hz or less. Therefore, the first low-pass filter 124 and the second low-pass filter 126 are substantially determined from the output signal So (t) of the first photosensor 120 and the output signal Sp (t) of the second photosensor 122, respectively. Transmits only the DC component. As described above, Ro (t) and Rp (t), which are non-pulse wave signals, do not include a body motion signal in the state where there is no body motion in the measurement site of the living body, and are constant values Ro and Rp, respectively. Since the first low-pass filter 124 and the second low-pass filter 126 can express the pulse from the output signal So (t) of the first photosensor 120 and the output signal Sp (t) of the second photosensor 122. The wave signals Po (t) and Pp (t) can be removed, and only the non-pulse wave signals Ro and Rp can be separated and detected.

  Note that when there is a body motion at the measurement site of the living body, the non-pulse wave signals Ro (t) and Rp (t) change according to the body motion, so the output signal of the first optical sensor 120 The So (t) and the output signal Sp (t) of the second optical sensor 122 include signals having various frequencies of 0.1 to 100 Hz. At this time, the frequency range of the output signal So (t) of the first photosensor 120 and the output signal Sp (t) of the second photosensor 122 is the frequency range of the pulse wave signals Po (t) and Pp (t). Since it overlaps with (0.3-3 Hz), the low-pass filter cannot separate and extract only the non-pulse wave signal.

  Thus, in a state where there is no body movement in the measurement site of the living body, the output signal of the first low-pass filter 124 corresponds to Ro, and the output signal of the second low-pass filter 126 corresponds to Rp. The first divider 132 has a function of dividing the output signal of the second low-pass filter 126 by the output signal of the first low-pass filter 124. Therefore, in a state where there is no body movement at the measurement site of the living body, the output signal of the first divider 132 corresponds to the constant m.

  Both the first high-pass filter 128 and the second high-pass filter 130 shown in FIG. 1 have a function of transmitting only frequency components of 0.3 Hz or higher. As described above, Ro (t) and Rp (t), which are non-pulse wave signals, do not include a body motion signal in the state where there is no body motion in the measurement site of the living body, and are constant values Ro and Rp, respectively. Therefore, the first high-pass filter 128 and the second high-pass filter 130 can generate a direct current from the output signal So (t) of the first photosensor 120 and the output signal Sp (t) of the second photosensor 122. The non-pulse wave signals Ro and Rp, which are components, are removed, and only the pulse wave signals Po (t) and Pp (t) can be separated and detected.

  When body movement is present at the measurement site of the living body, the frequency ranges of the output signal So (t) of the first photosensor 120 and the output signal Sp (t) of the second photosensor 122 are as described above. Since it overlaps with the frequency range (0.3 to 3 Hz) of the pulse wave signals Po (t) and Pp (t), the high-pass filter cannot separate and extract the pulse wave signal.

  Thus, in a state where there is no body movement in the measurement site of the living body, the output signal of the first high-pass filter 128 corresponds to Po (t), and the output signal of the second high-pass filter 130 corresponds to Pp (t). To do. The second divider 134 has a function of dividing the output signal of the second high-pass filter 130 by the output signal of the first high-pass filter 128. Therefore, in a state where there is no body movement at the measurement site of the living body, the output signal of the second divider 134 corresponds to the constant n.

  The computer 140 sets the amplification factor of the variable gain amplifier 136 to 1 / m based on the output signal of the first divider 132. At this time, the output signal S (t) of the differential amplifier 138 is expressed as (Equation 8).

  Substituting (Equation 1) to (Equation 4) into (Equation 8) gives the result as (Equation 9).

  As shown in (Equation 9), it can be seen that the output signal S (t) of the differential amplifier 138 includes only the pulse wave signal.

  Next, a pulse wave measurement procedure using the pulse wave measurement device 100 according to the present embodiment will be described. First, the subject inserts a finger 158 to be a measurement site into the mounting ring 104 of the pulse wave measuring device 100.

  Next, the measurement start switch 106 is pushed while the subject holds the finger 158 that is the measurement site without moving. When the measurement start switch 106 is pressed, the above operation is performed, so that the computer 140 sets the gain of the variable gain amplifier 136 to 1 / m based on the output signal of the first divider 132.

  When the setting of the gain of the variable gain amplifier 136 is completed, the measurement preparation completion display lamp 108 is turned on. Thus, the subject can know that the measurement preparation has been completed. After the measurement preparation completion display lamp 108 is turned on, the subject returns to a normal activity that may cause movement of the measurement site, and the pulse wave measurement device 100 performs pulse wave measurement. The measurement result is displayed on the display 146.

  As can be seen from (Equation 9), except for the case of m = n, the pulse wave signal can be measured using the pulse wave measuring device and the pulse wave measuring method according to the present invention. Here, the pulse wave measuring device 100 shown in FIGS. 1 to 3 has a configuration other than the mounting ring 104 and the measurement preparation completion display lamp 108, and the interval between the irradiation light emitting hole 142 and the reflected light incident hole 144 is 9 mm. The set pulse wave measuring device was made as a prototype. The above-described method is performed in such a manner that the irradiation light exit hole 142 and the reflected light incident hole 144 of the prototype pulse wave measuring device are pressed between the first joint and the second joint of the index finger of the left hand of the person and there is no movement of the finger. As a result, the constants m and n were measured, and m = 3.3 and n = 2.4.

  A living body is not optically isotropic and exhibits dichroism. That is, the refractive index and the absorptance differ depending on the polarization direction. As a result, the intensity of the reflected light and the polarization direction change depending on the polarization direction of the irradiation light. Bipolar dichroism of a living body is not uniform and varies depending on the part. It also varies depending on the pressure applied to the living body. Therefore, since the polarization characteristics of the reflected light change depending on the change in the irradiation position of the irradiation light and the degree of contact between the mounting ring and the measurement site, the constants m and n for extracting the pulse wave signal change. Therefore, it is preferable to reset the constants m and n every time the device ring 104 of the pulse wave measuring device 100 is attached.

  As described above, according to the pulse wave measuring apparatus 100 according to the present embodiment, only one light source 112 is used, and the computer 140 controls the amplification factor of the variable gain amplifier 136 based on the output signal of the first divider 132. Thus, the non-pulse wave signal is reduced in the differential amplifier 138, and the pulse wave signal can be measured with high accuracy from the output signal of the differential amplifier 138.

  Further, according to the pulse wave measuring apparatus 100 according to the present embodiment, the light reception angle of the polarization beam splitter 118 is limited by the reflected light incident hole 144 and only the diffuse reflection light within the layer is detected. The ratio of the included body motion signal is reduced, and the SN ratio can be improved.

(Embodiment 2)
Next, a pulse wave measuring apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing an internal configuration of apparatus main body 502 in pulse wave measuring apparatus 500 according to the present embodiment.

  The pulse wave measuring apparatus 500 according to the present embodiment is different from the pulse wave measuring apparatus 100 according to the first embodiment in that a polarizer driving unit 516 is provided inside the apparatus main body 502. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Based on a control signal from the computer 540, the polarizer driving unit 516 rotates the polarizer 114 and the light source 112 to the right or left in a plane perpendicular to the optical axis of irradiation light (z direction in FIG. 5). It has a function of setting the rotation angle Θ of the polarizer 114 and the light source 112. Here, the computer 540 corresponds to an amplification factor control unit, a calculation unit, and a drive control unit in the present invention.

  Next, the setting operation of the rotation angle Θ of the polarizer 114 and the light source 112 by the polarizer driving unit 516 will be described with reference to FIG. FIG. 6 is a graph showing the relationship between the rotation angle Θ of the polarizer 114 and the light source 112 and the value of the ratio n / m between the constants n and m. In FIG. 6, the horizontal axis indicates the rotation angle Θ of the polarizer 114 and the light source 112, and the vertical axis indicates the value of the ratio n / m between the constants n and m. When Θ = 0 °, the polarization direction of the irradiation light 550 is the y direction.

  A living body is not optically isotropic and exhibits dichroism. That is, the refractive index and the absorptance differ depending on the polarization direction. As a result, the intensity of the reflected light and the polarization direction change depending on the polarization direction of the irradiation light. Bipolar dichroism of a living body is not uniform and varies depending on the part. It also changes depending on the pressure applied to the living body. The polarization characteristics of the reflected light change as the irradiation position of the mounting ring and the contact position between the mounting ring and the measurement site change depending on the mounting position and mounting direction of the mounting ring with respect to the finger. The constants m and n change.

  As shown in FIG. 6, when the mounting position of the mounting ring with respect to the finger is the first position 160 in FIG. 2, when the rotation angle Θ of the polarizer 114 and the light source 112 is swept, the ratio n / m of constants n and m As shown by the solid line, the value of changes in a square shape of a sine wave, and shows a minimum value at a black dot. Similarly, when the mounting position of the mounting ring with respect to the finger is the second position 162 in FIG. 2, the ratio n / m of the constants n and m is determined by sweeping the rotation angle Θ of the polarizer 114 and the light source 112. The value varies along the alternate long and short dash line, and shows the minimum value at the black square point. Further, when the mounting position of the mounting ring with respect to the finger is the third position 164 in FIG. 2, the value of the ratio n / m of the constants n and m is obtained by sweeping the rotation angle Θ of the polarizer 114 and the light source 112. Changes along the broken line and shows the minimum value at the point of the black triangle.

  As shown in (Expression 8), the smaller the value of the ratio n / m between the constants n and m, the larger the pulse wave signal in the output signal S (t) of the differential amplifier 138, so the SN ratio improves. . Accordingly, the polarizer driving unit 516 sets the rotation angle Θ of the polarizer 114 and the light source 112 based on the control signal from the computer 540 at the position where the value of the ratio n / m between the constants n and m shows the minimum value. Thus, the SN ratio can be improved.

  Next, a pulse wave measurement procedure using pulse wave measurement apparatus 500 according to the present embodiment will be described. First, the subject inserts a finger as a measurement site into the mounting ring 104 of the pulse wave measuring device 500.

  Next, the measurement start switch 106 is pressed in a state where the subject holds the finger serving as the measurement site so as not to move. When the measurement start switch 106 is pressed, the computer 540 controls the polarizer driving unit 516 to sweep the rotation angle Θ of the polarizer 114 and the light source 112. At the same time, the computer 540 calculates the value of the ratio n / m between the constants n and m based on the output signal of the second divider 134 and the output signal of the first divider 132, and n / m Finds the rotation angle Θmin when is the minimum value.

  Next, the computer 540 controls the polarizer driving unit 516 to set the rotation angle of the polarizer 114 and the light source 112 to Θmin, and sets the gain of the variable gain amplifier 136 to 1 / m. When the setting of the rotation angle of the polarizer 114 and the light source 112 and the amplification factor of the variable gain amplifier 136 are completed, the measurement ready display lamp 108 is turned on. Thus, the subject can know that the measurement preparation has been completed.

  After the measurement preparation completion display lamp 108 is turned on, the subject returns to normal activity in which the measurement site may move, and the pulse wave measurement device 500 performs pulse wave measurement. The measurement result is displayed on the display 146.

  As shown in FIG. 5, the rotation angle Θmin of the polarizer 114 and the light source 112 when the values of the constants m and n and the ratio n / m between the constants n and m show the minimum values is the mounting position of the device ring 104. Therefore, it is preferable to set the rotation angle of the polarizer 114 and the light source 112 and the gain of the variable gain amplifier 136 each time the device ring 104 is mounted.

  As described above, according to pulse wave measuring apparatus 500 according to the present embodiment, the same effect as pulse wave measuring apparatus 100 according to the first embodiment can be obtained. In addition, the polarizer driving unit 516 sets the rotation angle Θ of the polarizer 114 and the light source 112 based on the control signal from the computer 540 at a position where the value of the ratio n / m between the constants n and m shows the minimum value. Thus, the SN ratio can be improved.

(Embodiment 3)
Next, a pulse wave measuring apparatus according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 7 is a side view of the pulse wave measuring apparatus 700 according to the present embodiment, and FIG. 8 is a front view of the pulse wave measuring apparatus 700.

  The pulse wave measuring apparatus 700 according to the present embodiment is different from the pulse wave measuring apparatus 500 according to the second embodiment in that the mounting ring 104 includes a warning lamp 710. Since other configurations are the same as those of the second embodiment, description thereof is omitted. Here, the warning lamp 710 corresponds to a warning output unit in the present invention.

  The computer 540 of the pulse wave measuring apparatus 700 according to the present embodiment stores a threshold for the value of the ratio n / m between the constants n and m in an internal memory. After the computer 540 calculates the ratio n / m of the constants n and m while sweeping the rotation angle Θ of the polarizer 114 and the light source 112 and detects the rotation angle Θmin when n / m shows the minimum value The computer 540 reads the threshold value stored in the memory and compares the threshold value with the minimum value of n / m. As a result of the comparison, if the minimum value of n / m exceeds the threshold value, the computer 540 sends a command to the warning lamp 710 to turn on the warning lamp 710. Here, the threshold is preferably set to 0.8 or less.

  The larger the value of the ratio between the output signal of the second divider and the output signal of the first divider, the smaller the output signal of the differential amplifier, so the SN ratio becomes lower. As the warning lamp 710 is turned on, the subject has an unsuitable measurement site because the value of the ratio between the output signal of the second divider and the output signal of the first divider exceeds the threshold value. Therefore, it can be known that the measurement site needs to be changed.

  When the warning lamp 710 is turned on, the subject changes the position of the mounting ring 104 with respect to the finger and then presses the measurement start switch 106 again. When the computer 540 determines that the minimum value of n / m is equal to or less than the threshold value, the measurement preparation completion display lamp 108 is turned on. Thereby, the subject can know that the measurement preparation is completed.

  As described above, according to pulse wave measuring apparatus 700 according to the present embodiment, the same effects as those of pulse wave measuring apparatuses 100 and 500 according to Embodiments 1 and 2 are obtained. In addition, since the subject can know that the measurement site is inappropriate, the SN ratio can be prevented from decreasing.

  In the first to third embodiments, the example in which the variable gain amplifier 136 is disposed between the second optical sensor 122 and the differential amplifier 138 has been described. However, the present invention is not limited to this. The variable gain amplifier may be arranged between the first photosensor 120 and the differential amplifier 138 instead of between the second photosensor 122 and the differential amplifier 138. In this case, the computers 140 and 540 may set the gain of the variable gain amplifier to m based on the output signal of the first divider 132. At this time, the output signal S ′ (t) of the differential amplifier 138 is expressed as (Equation 10).

  Substituting (Equation 1) to (Equation 4) into (Equation 10) gives the result as (Equation 11).

  As shown in (Equation 11), it can be seen that the output signal S ′ (t) of the differential amplifier 138 includes only the pulse wave signal.

(Embodiment 4)
Next, a pulse wave measuring apparatus according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 9 is a block diagram showing an internal configuration of apparatus main body 902 in pulse wave measuring apparatus 900 according to the present embodiment. In addition, about the structure which has the function similar to the pulse wave measuring device 100 which concerns on Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 9, the apparatus main body 902 includes a light source 112, a first polarizer 914, an optical modulator 960, a signal generator 962, a second polarizer 964, an optical sensor 966, a demultiplexer 968, 3 low-pass filter 970, fourth low-pass filter 972, first low-pass filter 124, second low-pass filter 126, first high-pass filter 128, second high-pass filter 130, first divider 132, first 2 divider 134, variable gain amplifier 136, differential amplifier 138, computer 940, irradiation light exit hole 142, reflected light incident hole 144, and display 146 which is a display unit. Here, the computer 940 corresponds to an amplification factor control unit, a calculation unit, and a signal generator control unit in the present invention.

  The light modulator 960 has a function of modulating the polarization direction of light emitted from the light source 112 and transmitted through the first polarizer 914. In the case of pulse wave measuring apparatus 900 according to the present embodiment, modulated irradiation light 974 is generated by switching the polarization direction between the x direction and the y direction at a modulation frequency of 3.3 KHz. Here, the signal generator 962 supplies a modulation signal to the optical modulator 960 and the demultiplexer 968 based on the control signal from the computer 940.

  A part of the modulated irradiation light 974 irradiated to the living body 152 propagates while diffusing in the living tissue, and is emitted from the living body 152 as reflected light. The reflected light from the living body 152 enters the second polarizer 964. The second polarizer 964 is arranged so that the polarization direction transmits the component in the y direction. The light transmitted through the second polarizer 964 enters the optical sensor 966.

  Since the light incident on the optical sensor 966 has a polarization direction orthogonal to the modulated irradiation light 974 when the polarization direction of the modulated irradiation light 974 is the x direction, the output signal of the optical sensor 966 is the pulse according to the first embodiment. This corresponds to the output signal So (t) of the first optical sensor 120 in the wave measuring device 100. On the other hand, when the polarization direction of the modulated irradiation light 974 is the y direction, the light incident on the optical sensor 966 has the same polarization direction as that of the modulated irradiation light 974. Therefore, in the pulse wave measuring apparatus 100 according to Embodiment 1. This corresponds to the output signal Sp (t) of the second photosensor 122. That is, the optical sensor 966 alternately outputs signals corresponding to Sp (t) or So (t) in synchronization with the modulation signal of the optical modulator 960.

  An output signal of the optical sensor 966 is input to the demultiplexer 968. The demultiplexer 968 synchronizes the output signal of the optical sensor 966 with the modulation signal from the signal generator 962, and sends the modulated irradiation light 974 to the third low-pass filter 970 when the polarization direction of the modulation irradiation light 974 is in the x direction. Is switched to the fourth low-pass filter 972 and output.

  The third low-pass filter 970 and the fourth low-pass filter 972 transmit only signals having a frequency lower than the modulation frequency of 3.3 KHz, and block signals having a frequency equal to or higher than the modulation frequency. Therefore, the output signal of the third low-pass filter 970 corresponds to So (t), and the output signal of the fourth low-pass filter 972 corresponds to Sp (t).

  The method for setting the amplification factor of the variable gain amplifier 136 is the same as that of the pulse wave measuring apparatus 100 according to the first embodiment, and thus the description thereof is omitted.

  As described above, according to pulse wave measurement apparatus 900 according to the present embodiment, the same effect as pulse wave measurement apparatus 100 according to Embodiment 1 can be obtained.

(Embodiment 5)
Next, a pulse wave measuring apparatus according to Embodiment 5 of the present invention will be described with reference to FIGS. FIG. 10 is a block diagram showing an internal configuration of the apparatus main body 982 in the pulse wave measuring apparatus 980 according to the present embodiment, and FIG. 11 shows the polarization direction of the modulated irradiation light 984 emitted from the pulse wave measuring apparatus 980. It is a schematic diagram shown. In addition, the same code | symbol is attached | subjected about the structure which has the function similar to the pulse-wave measuring apparatus 900 which concerns on Embodiment 4, and description is abbreviate | omitted.

  The computer 986 in the pulse wave measuring apparatus 980 according to the present embodiment controls the light modulator 960 via the signal generator 988, thereby changing the polarization direction of the modulated irradiation light 984 as shown in FIG. The first polarization direction rotated counterclockwise from the direction by an angle θ and the second polarization direction rotated counterclockwise from the y direction by an angle θ are set to be switched alternately.

  By sweeping the rotation angle θ in the polarization direction of the modulated irradiation light 984, as in the case where the polarizer drive unit 516 sweeps the rotation angle Θ of the polarizer 114 and the light source 112 in the second embodiment, the constants n and m The ratio n / m can be changed. Similar to the second embodiment, the computer 986 obtains the rotation angle θmin in the polarization direction of the modulated irradiation light 984 when n / m indicates the minimum value in a state where there is no movement of the measurement site in the living body. The computer 986 controls the optical modulator 960 via the signal generator 988 to set the rotation angle of the polarization direction of the modulated irradiation light 984 to θmin, so that the output signal S (t) of the differential amplifier 138 is output. Since the pulse wave signal can be maximized, the S / N ratio is maximized.

  As described above, according to pulse wave measuring apparatus 980 according to the present embodiment, the same effect as pulse wave measuring apparatus 100 according to the first embodiment can be obtained. Further, since the mechanical operation is not required when sweeping the rotation angle θ in the polarization direction of the modulated irradiation light 984, the rotation angle in the polarization direction of the modulation irradiation light 984 can be determined in a short time. As a result, it is possible to shorten the time during which the subject maintains the state where the measurement site does not move.

  In the fourth and fifth embodiments, the example in which the variable gain amplifier 136 is disposed between the fourth low-pass filter 972 and the differential amplifier 138 has been described, but the present invention is not limited to this. A variable gain amplifier may be disposed between the third low-pass filter 970 and the differential amplifier 138 instead of between the fourth low-pass filter 972 and the differential amplifier 138. In this case, the computers 940 and 986 may set the gain of the variable gain amplifier to m based on the output signal of the first divider 132. At this time, since the output signal S ′ (t) of the differential amplifier 138 is expressed by (Equation 11) as described above, the output signal S ′ (t) of the differential amplifier 138 includes only the pulse wave signal. .

  According to the present invention, since the pulse wave can be measured with high accuracy even in a state in which the subject spends normal daily life, it can be used for health management based on the pulse wave and control of home appliances. it can.

The side view of the pulse wave measuring device concerning one embodiment of the present invention Front view of the pulse wave measurement device Block diagram showing the internal configuration of the main body of the pulse wave measuring device The graph which shows typically the example of the output signal of the 1st optical sensor in the same pulse wave measuring device, the 2nd optical sensor, and a differential amplifier The block diagram which shows the structure inside the apparatus main body in the pulse wave measuring device which concerns on other embodiment of this invention. The graph which shows the relationship between the rotation angle (theta) of the polarizer and light source in the same pulse wave measuring device, and the value of ratio n / m of constant n and m Side view of a pulse wave measuring device according to still another embodiment of the present invention. Front view of the pulse wave measurement device The block diagram which shows the structure inside the apparatus main body in the pulse-wave measuring apparatus which concerns on other embodiment of this invention. The block diagram which shows the structure inside the apparatus main body in the pulse-wave measuring apparatus which concerns on other embodiment of this invention. Schematic diagram showing the polarization direction of modulated irradiation light emitted from the pulse wave measurement device

Explanation of symbols

100, 500, 700, 900, 980 Pulse wave measuring device 102, 502, 902, 982 Device main body 104 Wear ring 106 Measurement start switch 108 Measurement preparation completion display lamp 112 Light source 114 Polarizer 118 Polarizing beam splitter 120 First optical sensor 122 second optical sensor 124 first low-pass filter 126 second low-pass filter 128 first high-pass filter 130 second high-pass filter 132 first divider 134 second divider 136 variable gain amplifier 138 difference Dynamic amplifier 140, 540, 940, 986 Computer 142 Irradiation light exit hole 144 Reflected light incident hole 146 Display 150, 550 Irradiation light 152 Living body 154 First reflected light 156 Second reflected light 158 Finger 160 First position 162 First 2 position 164 Third position 516 Polarizer driver 710 Warning lamp 914 First polarizer 960 Optical modulator 962, 988 Signal generator 964 Second polarizer 966 Photosensor 968 Demultiplexer 970 Third low-pass filter 972 Fourth Low pass filter 974,984 modulated light

Claims (9)

(A) a step of irradiating the measurement site with irradiation light that is polarized in a state where there is no movement in the measurement site of the living body that is the measurement target;
(B) Of the reflected light reflected at the measurement site with the irradiation of the irradiation light in the step A with no movement at the measurement site, the polarization direction is the same as that of the irradiation light and the orthogonal polarization direction. A step of separating and detecting a first polarization component that is one of the polarization directions and a second polarization component that is a polarization direction orthogonal to the first polarization component;
(C) For each of the first signal corresponding to the first polarization component and the second signal corresponding to the second polarization component detected in the step B, the pulse wave signal and the pulse wave signal are excluded. Separating the signal into a non-pulse wave signal,
(D) Pulse wave signal information related to a ratio between the pulse wave signal of the first signal and the pulse wave signal of the second signal, and non-pulse wave signals of the first signal and non-pulse signals of the second signal Obtaining non-pulse wave signal information relating to a ratio with a pulse wave signal;
(E) a step of irradiating the measurement site with the irradiation light in a state where the measurement site of the living body can be moved;
(F) Of the reflected light reflected at the measurement site in accordance with the irradiation of the irradiation light in the step E in a state where the measurement site can move, the same polarization direction as the irradiation light and a polarization direction orthogonal to the irradiation light A step of separating and detecting a third polarization component having one of the polarization directions and a fourth polarization component having a polarization direction orthogonal to the third polarization component; and (G) the step Using the pulse wave signal information and the non-pulse wave signal information acquired in D, corresponding to the third signal and the fourth polarization component corresponding to the third polarization component detected in the step F A pulse wave measurement method including a step of extracting a pulse wave signal of the living body in a state where the measurement site may move by calculating a fourth signal to be performed. In the steps B and F, out of the reflected light reflected at the measurement site, the light enters the living body from the irradiation position of the irradiation light at the measurement site, and goes outside the living body at a position away from the irradiation position. The pulse wave measuring method according to claim 1, wherein only the reflected light emitted is detected. In the step D, a ratio value n of the pulse wave signal of the first signal and the pulse signal of the second signal is used as the pulse wave signal information, and the first signal is used as the non-pulse wave signal information. And a value m of the ratio of the non-pulse wave signal of the second signal to the non-pulse wave signal of the second signal,
In step G,
By subtracting a signal obtained by multiplying the third signal by 1 / m from the third signal, or subtracting the fourth signal from a signal obtained by multiplying the third signal by m, the pulse wave signal of the living body The pulse wave measurement method according to claim 1, wherein the pulse wave is extracted. (H) performing steps A to D using a plurality of irradiation lights having different polarization directions, and calculating a ratio value n / m of the n and the m for each of the irradiation lights; I) further including the step of extracting the irradiation light having the minimum value of n / m from a plurality of the irradiation lights using the calculation result in the step H;
The pulse wave measuring method according to claim 3, wherein the steps E to G are performed using the irradiation light extracted in the step I. A pulse wave measuring device used in the pulse wave measuring method according to claim 3 or 4,
A light source that emits the irradiation light that irradiates the measurement site;
A polarizer for limiting the polarization direction of the irradiation light;
Of the reflected light reflected at the measurement site, a polarization beam splitter that separates a component in the same polarization direction as the irradiation light and a component in the polarization direction orthogonal to the irradiation light,
A first optical sensor for detecting a component in one polarization direction among a component in the same polarization direction as the irradiation light and a component in a polarization direction orthogonal to the irradiation light;
A second optical sensor for detecting a component in the polarization direction orthogonal to the component in the polarization direction detected by the first optical sensor;
A first low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the first photosensor;
A second low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the second photosensor;
A first high-pass filter that transmits a frequency component included in a frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the first photosensor;
A second high-pass filter that transmits a frequency component included in the frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the second photosensor;
A first divider for dividing the output signal of the second low-pass filter by the output signal of the first low-pass filter;
A second divider for dividing the output signal of the second high-pass filter by the output signal of the first high-pass filter;
A variable gain amplifier that amplifies an output signal of one of the first photosensor and the second photosensor;
A differential amplifier for amplifying a difference between an output signal of the other of the first optical sensor and the second optical sensor and an output signal of the variable gain amplifier; and an output signal of the first divider. A pulse wave measuring device comprising an amplification factor control unit for controlling the amplification factor of the variable gain amplifier. A polarizer driver for rotating the polarizer;
An arithmetic unit that calculates a value of a ratio between an output signal of the second divider and an output signal of the first divider; and a drive that controls the polarizer driving unit so that the value is minimized. The pulse wave measurement device according to claim 5, further comprising a control unit. A pulse wave measuring device used in the pulse wave measuring method according to claim 3 or 4,
A light source that emits the irradiation light that irradiates the measurement site;
A first polarizer for limiting a polarization direction of the irradiation light;
An optical modulator that modulates a polarization direction of the irradiation light transmitted through the first polarizer;
A modulation signal for operating the optical modulator such that the polarization direction of the irradiation light is alternately switched in two directions orthogonal to each other, and a modulation signal having a frequency higher than the frequency band of the pulse wave signal is transmitted to the optical modulator. A signal generator,
A second polarizer that limits the polarization direction of the reflected light reflected at the measurement site;
An optical sensor for detecting the reflected light transmitted through the second polarizer;
A demultiplexer that separates an output signal of the optical sensor into an in-phase component and an anti-phase component of the modulation signal;
A third low-pass filter that transmits only a frequency component lower than the modulation signal from a signal corresponding to one of the in-phase component and the anti-phase component output from the demultiplexer;
A fourth low-pass filter that transmits only a frequency component lower than the modulation signal from a signal corresponding to the other component of the in-phase component and the anti-phase component output from the demultiplexer;
A first low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the third low-pass filter;
A second low-pass filter that transmits only a frequency component lower than the frequency band of the pulse wave signal from the output signal of the fourth low-pass filter;
A first high-pass filter that transmits a frequency component included in a frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from an output signal of the third low-pass filter;
A second high-pass filter that transmits a frequency component included in the frequency band of the pulse wave signal and blocks a frequency component lower than the frequency band of the pulse wave signal from the output signal of the fourth low-pass filter;
A first divider for dividing the output signal of the second low-pass filter by the output signal of the first low-pass filter;
A second divider for dividing the output signal of the second high-pass filter by the output signal of the first high-pass filter;
A variable gain amplifier that amplifies an output signal of any one of the third low-pass filter and the fourth low-pass filter;
A differential amplifier that amplifies a difference between the output signal of the other of the third low-pass filter and the fourth low-pass filter and the output signal of the variable gain amplifier; and an output signal of the first divider A pulse wave measuring device comprising an amplification factor control unit for controlling the amplification factor of the variable gain amplifier. A calculation unit for calculating a value of a ratio between the output signal of the second divider and the output signal of the first divider; and a signal generator for controlling the signal generator so that the value is minimized. The pulse wave measuring device according to claim 7, further comprising a device control unit. A calculation unit that calculates a value of a ratio between the output signal of the second divider and the output signal of the first divider, and a warning output unit that outputs a warning when the value exceeds a threshold value The pulse wave measuring device according to claim 5 or 7 provided.

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