JP6179064B2 - Pulse wave measuring device and signal processing device - Google Patents

Description

  The present invention relates to a technique for measuring a pulse wave of a living body.

  A technique for measuring the pulse of a living body using light is known. For example, Patent Document 1 describes a signal processing method for separating a pulse wave signal and an artifact signal from two measurement signals extracted from the same medium in a pulse photometer.

JP 2009-261458 A

When measuring pulse waves using light of two wavelengths, signal processing such as signal amplification is performed on two signals observed by these lights. However, when signal processing is performed on two signals with a circuit configuration of another system, signal noise having no correlation with the other signal is mixed into the two signals due to variations in circuit characteristics. In this case, the correlation between the two signals becomes low, which may adversely affect signal separation as described in Patent Document 1, for example.
An object of the present invention is to increase the correlation between the first signal and the second signal when the signal processing is performed on the first signal and the second signal by different signal processing units.

  The pulse wave assumption device according to the present invention includes a first irradiation unit that irradiates a living body with first light, a second irradiation unit that irradiates the living body with second light, and the body that has passed through the living body. A first light receiving unit that receives the first light, converts the received first light into a first signal, and receives the second light that has passed through the living body; A second light receiving unit that converts the light into a second signal, a first signal processing unit that performs first signal processing on the first signal, and second signal processing on the second signal. A first signal processing section and a second signal subjected to the second signal processing, and a first signal subjected to the first signal processing has a lower correlation than a first threshold And a first removing unit that removes the signal component and outputs a second signal from which the first signal component has been removed. According to this configuration, when the signal processing is performed on the first signal and the second signal by different signal processing units, the correlation between the first signal and the second signal can be increased.

  The pulse wave measuring device has a second signal component whose correlation with the second signal subjected to the second signal processing is lower than a threshold value from the first signal subjected to the first signal processing. And a second removal unit that outputs the first signal from which the second signal component is removed. According to this configuration, even when both the first signal and the second signal include signal components whose correlation with other signals is lower than the threshold, the first signal and the second signal Correlation can be increased.

  The first removal unit or the second removal unit may remove the first signal component or the second signal component using an adaptive filter. According to this configuration, the correlation between the first signal and the second signal can be increased with a simple configuration.

  The pulse wave measuring device includes: a first signal subjected to the first signal processing; and a second signal from which the first signal component has been removed by the first removing unit; or the second signal. A pulsating component indicating the pulsation of the living body from the first signal from which the second signal component has been removed by the removing unit and the second signal from which the first signal component has been removed by the first removing unit And a separation unit for separating the noise component. According to this structure, the precision which isolate | separates a pulsation component and a noise component can be improved.

  The first light and the second light may have different wavelengths. According to this configuration, the correlation between the first signal and the second signal can be increased in the configuration in which the pulse wave is measured using light of two wavelengths.

  In the signal processing device according to the present invention, the first irradiation unit irradiates the living body with the first light, the first light receiving unit receives the first light that has passed through the living body, and receives the received first light. When the first light is converted into the first signal, the first signal processing unit that performs the first signal processing on the first signal and the second irradiation unit irradiate the living body with the second light, When the second light receiving unit receives the second light passing through the living body and converts the received second light into a second signal, the second signal is subjected to second signal processing. A first signal having a lower correlation than a threshold value between the second signal processing unit and the second signal subjected to the second signal processing and the first signal subjected to the first signal processing. And a first removal unit that outputs a second signal from which the first signal component has been removed. According to this configuration, when the signal processing is performed on the first signal and the second signal by different signal processing units, the correlation between the first signal and the second signal can be increased.

Diagram showing the appearance of the pulse wave measurement device Block diagram showing the configuration of the pulse wave measurement device Diagram showing the penetration of light into a living body Diagram showing the path of green light and red light in the living body The figure which shows the input-output characteristic of a 1st amplifier circuit and a 2nd amplifier circuit The figure which shows the distortion of an amplifier circuit. Block diagram showing functional configuration of CPU Conceptual diagram of adaptive filter The figure which shows the signal observation model of G signal and R signal The block diagram which shows the function structure of CPU which concerns on a modification. Conceptual diagram of adaptive filter according to modification

  FIG. 1 is a diagram illustrating an appearance of a pulse wave measuring apparatus 1 according to the present embodiment. The pulse wave measuring device 1 is attached to a human hand 2. The pulse wave measuring device 1 includes a device main body 3 (an example of a signal processing device) that is worn on a human wrist and a pulse wave sensor 4. The apparatus main body 3 and the pulse wave sensor 4 are connected via a cable 5. The pulse wave sensor 4 is fixed to the palm side of the base of the index finger by a band 6 as shown in FIG.

  FIG. 2 is a block diagram showing the configuration of the pulse wave measuring device 1. The pulse wave measuring device 1 measures a pulse wave using light of two wavelengths. The apparatus body 3 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a display unit 14, an operation unit 15, an oscillation circuit 16, and a clock circuit 17. And a first signal processing unit 24a and a second signal processing unit 24b. The first signal processing unit 24a includes a first filter unit 21a, a first amplifier circuit 22a, and a first A / D (analog to digital) conversion unit 23a. The second signal processing unit 24b includes a second filter unit 21b, a second amplifier circuit 22b, and a second A / D conversion unit 23b. The pulse wave sensor 4 includes a drive circuit 18, a first light emitting unit 19a (an example of a first irradiation unit), a second light emitting unit 19b (an example of a second irradiation unit), and a first light receiving unit 20a. And a second light receiving unit 20b.

  The CPU 11 controls each part of the pulse wave measuring device 1 by executing a control program. The ROM 12 is a read-only nonvolatile memory. For example, a basic system program executed by the CPU 11 is stored in the ROM 12. The RAM 13 is a volatile memory used as a work area for the CPU 11. In the RAM 13, for example, various data generated during execution of the control program by the CPU 11 are temporarily stored. The display unit 14 is a liquid crystal display, for example. The display unit 14 displays various information related to pulse wave measurement results and pulse wave measurement under the control of the CPU 11. The operation unit 15 includes a plurality of operation buttons used for operating the pulse wave measuring device 1, for example. The operation unit 15 supplies an operation signal corresponding to a user operation to the CPU 11. The oscillation circuit 16 supplies a clock signal to the CPU 11. The timer circuit 17 measures time under the control of the CPU 11.

  The drive circuit 18 drives the first light emitting unit 19a and the second light emitting unit 19b. For example, when an operation for instructing start of pulse wave measurement is performed using the operation unit 15, the drive circuit 18 alternately drives the first light emitting unit 19 a and the second light emitting unit 19 b. The first light emitting unit 19a includes a light emitting element that emits green light Lg (an example of first light). The peak wavelength of the green light Lg is 525 nm. The second light emitting unit 19b includes a light emitting element that emits red light Lr (an example of second light). The peak wavelength of the red light Lr is 620 nm. The peak wavelength of the red light Lr is larger than the peak wavelength of the green light Lg. When the first light emitting unit 19 a and the second light emitting unit 19 b are driven by the drive circuit 18, the first light emitting unit 19 a and the second light emitting unit 19 b irradiate the measurement site in the living body with light.

  FIG. 3 is a diagram showing the degree of penetration of light into a living body. The vertical axis | shaft shown in FIG. 3 shows the peak wavelength [nm] of light. The horizontal axis shown in FIG. 3 indicates the degree of light penetration into the living body. This penetrance refers to the depth at which light reaches in vivo. This depth refers to the distance from the surface of the living body. As shown in FIG. 3, the penetration degree of light into the living body varies depending on the wavelength. For example, the peak wavelength of the green light Lg is 525 nm, and the peak wavelength of the red light Lr is 620 nm. In this case, the penetration degree of the red light Lr is larger than the penetration degree of the green light Lg.

  FIG. 4 is a diagram illustrating paths of the green light Lg and the red light Lr in the living body. The first light emitting unit 19a, the second light emitting unit 19b, the first light receiving unit 20a, and the second light receiving unit 20b are configured such that the measurement site having the same depth is irradiated with the green light Lg and the red light Lr. Placed in position. As described above, since the penetrability of the red light Lr is larger than that of the green light Lg, the red light Lr basically passes through a deeper part of the living body than the green light Lg. However, when the distance D2 between the second light emitting unit 19b and the second light receiving unit 20b is reduced, the red light L emitted from the second light emitting unit 19b is a ratio of the scattered light in the shallow part in the living body. Therefore, the average penetrance in the living body becomes small. That is, when the distance D2 between the second light emitting unit 19b and the second light receiving unit 20b is reduced, the red light Lr passes through a shallower part of the living body. Therefore, by making the distance D2 between the second light emitting unit 19b and the second light receiving unit 20b smaller than the distance D1 between the first light emitting unit 19a and the first light receiving unit 20a, green It can adjust so that the light Lg and the red light Lr may be irradiated to the measurement part of the same depth. In this case, the green light Lg is applied to the measurement site T1 as shown in FIG. As shown in FIG. 4B, the red light Lr is irradiated to the measurement site T2 having the same depth as the measurement site T1.

  The green light Lg emitted from the first light emitting unit 19a is reflected by the measurement site T1 and received by the first light receiving unit 20a. When receiving the green light Lg, the first light receiving unit 20a converts the received green light Lg into a first analog signal (an example of a first signal) and outputs the first analog signal. The first analog signal includes a measurement signal component indicating the pulsation of the blood vessel existing at the measurement site T1. The red light Lr emitted from the second light emitting unit 19b is reflected by the measurement site T2 and received by the second light receiving unit 20b. When receiving the red light Lr, the second light receiving unit 20b converts the received red light Lr into a second analog signal (an example of a second signal) and outputs the second analog signal. The second analog signal includes a measurement signal component indicating the pulsation of the blood vessel existing at the measurement site T2. As described above, since the measurement site T1 and the measurement site T2 have the same depth, it is considered that the same blood vessel exists in the measurement site T1 and the measurement site T2. Accordingly, the same measurement signal component is included in the first analog signal and the second analog signal.

  The first analog signal output from the first light receiving unit 20a is input to the first filter unit 21a shown in FIG. The first filter unit 21a includes an AC (Alternating Current) filter and a DC (Direct Current) filter (both not shown). When the first analog signal is input, the AC filter removes a pulsation component (AC component) indicating pulsation from the input first analog signal and outputs a DC component of the first analog signal. When the first analog signal is input, the DC filter removes the fluctuation component (DC component) of the baseline of the pulse wave from the input first analog signal and outputs the AC component of the first analog signal. .

  The second analog signal output from the second light receiving unit 20b is input to the second filter unit 21b. Similar to the first filter unit 21a, the second filter unit 21b includes an AC filter and a DC filter (not shown). When the second analog signal is input, the AC filter removes a pulsation component (AC component) indicating pulsation from the input second analog signal and outputs a DC component of the second analog signal. When the second analog signal is input, the DC filter removes the fluctuation component (DC component) of the baseline of the pulse wave from the input second analog signal and outputs the AC component of the second analog signal. .

  The AC component of the first analog signal output from the first filter unit 21a is input to the first amplifier circuit 22a. When the AC component of the first analog signal is input, the first amplifier circuit 22a amplifies and outputs the AC component of the input first analog signal. The AC component of the second analog signal output from the second filter unit 21b is input to the second amplifier circuit 22b. When the AC component of the second analog signal is input, the second amplifier circuit 22b amplifies and outputs the AC component of the input second analog signal. The gains of the first amplifier circuit 22a and the second amplifier circuit 22b are set by the CPU 11. For example, the CPU 11 sets the gain of the first amplifier circuit 22a and the signal intensity so that the signal intensity is the same between the signal output from the first amplifier circuit 22a and the signal output from the second amplifier circuit 22b. The gain of the second amplifier circuit 22b is set.

  The AC component of the first analog signal output from the first amplifier circuit 22a and the DC component of the first analog signal output from the first filter unit 21a are input to the first A / D conversion unit. The The first A / D conversion unit 23a includes a first A / D conversion circuit and a second A / D conversion circuit (not shown). When the AC component of the first analog signal is input, the first A / D conversion circuit converts the AC component of the input first analog signal from an analog signal to a digital signal and outputs the converted signal. Specifically, the first A / D conversion circuit samples and quantizes the AC component of the first analog signal at a preset sampling frequency. This sampling frequency is, for example, 100 Hz. Quantization is performed, for example, with 10 bits. When the DC component of the first analog signal is input to the second A / D conversion circuit, the DC component of the input first analog signal is converted into an analog signal in the same manner as the first A / D conversion circuit. To digital signal and output.

  The AC component of the second analog signal output from the second amplifier circuit 22b and the DC component of the second analog signal output from the second filter unit 21b are input to the second A / D conversion unit 23b. Is done. The second A / D converter 23b includes a third A / D converter circuit and a fourth A / D converter circuit (both not shown). When the AC component of the second analog signal is input to the third A / D conversion circuit, the AC component of the input second analog signal is converted into an analog signal in the same manner as the first A / D conversion circuit. To digital signal and output. When the DC component of the second analog signal is input to the fourth A / D conversion circuit, the DC component of the input second analog signal is converted into an analog signal in the same manner as the first A / D conversion circuit. To digital signal and output. Sampling data obtained by the sampling of the first A / D conversion unit 23a and the second A / D conversion unit 23b is supplied to the CPU 11, and the gains of the first amplification circuit 22a and the second amplification circuit 22b are set. It is used as a judgment material when doing.

  In the following description, a signal output from the first light receiving unit 20a and subjected to signal processing (an example of first signal processing) in the first signal processing unit 24a is referred to as a “G signal”. A signal output from the second light receiving unit 20b and subjected to signal processing (an example of second signal processing) in the second signal processing unit 24b is referred to as an “R signal”. The signal processing of the first signal processing unit 24a includes filter processing performed by the first filter unit 21a, signal amplification processing performed by the first amplification circuit 22a, and the first A / D conversion unit 23a. The A / D conversion process performed by is included. The signal processing of the second signal processing unit 24b includes filter processing performed by the second filter unit 21b, signal amplification processing performed by the second amplification circuit 22b, and a second A / D conversion unit 23b. The A / D conversion process performed by is included.

Since the first signal processing unit 24a and the second signal processing unit 24b have different circuit configurations, there are differences in circuit characteristics.
FIG. 5 is a diagram illustrating input / output characteristics of the first amplifier circuit 22a and the second amplifier circuit 22b. In FIG. 5, a line I1 indicates the input / output characteristics of the first amplifier circuit 22a, and a line I2 indicates the input / output characteristics of the second amplifier circuit 22b. As shown in FIG. 5, the first amplifier circuit 22a and the second amplifier circuit 22b have different input / output characteristics.

  FIG. 6 is a diagram illustrating distortion of the amplifier circuit. When the input / output characteristics of the amplifier circuit are nonlinear, the output waveform Wo is distorted with respect to the input waveform Wi. As shown in FIG. 5, when there is a difference in input / output characteristics between the first amplifier circuit 22a and the second amplifier circuit 22, the first amplifier circuit 22 and the second amplifier circuit 22 And different distortions in the R signal. This distortion appears as a signal noise component. Thereby, a signal noise component uncorrelated with the other signal is superimposed on the G signal or the R signal.

  In addition to the first amplifier circuit 22a and the second amplifier circuit 22b, the frequency characteristics are different between the first filter unit 21a and the second filter unit 21b due to, for example, individual differences between elements constituting the filter. There is a case. Further, the quantization error may be different between the first A / D converter 23a and the second A / D converter 23b. Even in such a case, a signal noise component having no correlation with the other signal is superimposed on the G signal or the R signal.

  Here, it is assumed that the G signal output from the first A / D converter 23a includes the first signal noise component in addition to the measurement signal component described above. In addition, the R signal output from the second A / D conversion unit 23b includes the first signal noise component and the second signal noise component in addition to the measurement signal component described above. .

  FIG. 7 is a block diagram illustrating a functional configuration of the CPU 11. The CPU 11 includes a first removal unit 41 and a separation unit 42. The G signal output from the first A / D conversion unit 23 a and the R signal output from the second A / D conversion unit 23 b are input to the first removal unit 41. When the G signal and the R signal are input, the first removal unit 41 uses an adaptive filter to remove a signal component having no correlation with the G signal from the input R signal. This “no correlation” means that the correlation with the G signal is strictly lower than the threshold value. “Removal” is a concept that includes not only completely removing uncorrelated signal components but also attenuating uncorrelated signal components.

  FIG. 8 is a conceptual diagram of an adaptive filter used by the first removal unit 41. The G signal output from the first A / D conversion unit 23 a is input to the delay unit 51. When the G signal is input, the delay unit 51 delays and outputs the input G signal. The G signal output from the delay unit 51 is input to the adder 52. The R signal output from the second A / D converter 23 b is input to an FIR (finite impulse response) filter 53. When an R signal is input, the FIR filter 53 performs a filtering process on the input R signal using a coefficient and outputs the filtered signal. The R signal output from the FIR filter 53 is input to the adder 52. When the G signal and the R signal are input, the adder 52 outputs a difference between the input G signal and the R signal as an error signal ε. The coefficient of the FIR filter 53 is updated using an algorithm such as an LMS (Least Mean Square) algorithm so that the expected value of the square of the error signal ε output from the adder 52 is minimized.

  As described above, the R signal includes the second signal noise component (an example of the first signal component) that is not included in the G signal. In this case, the FIR filter 53 removes the second signal noise component having no correlation with the G signal from the R signal. As a result, the R signal from which the second signal noise component has been removed is output from the FIR filter 53. Since the R signal includes only the measurement signal component and the first signal noise component as in the G signal, the R signal has a high correlation with the G signal.

  The G signal output from the first A / D conversion unit 23 a and the R signal output from the FIR filter 53 are input to the separation unit 42. When the G signal and the R signal are input, the separation unit 42 separates the pulse wave component and the body motion noise component from the input G signal and R signal. This body movement noise refers to an error caused by vibration when the body moves. When the separation unit 42 separates the pulse wave component and the body motion noise component, a pulse wave is obtained based on the pulse component.

  FIG. 9 is a diagram illustrating a signal observation model of the G signal and the R signal. In FIG. 9, p is a pulsation signal indicating pulsation at time tn, and n is a noise signal indicating noise at time tn. G is the first light receiving portion 20a, that is, the terminal for green light Lg, and R is the second light receiving portion 20b, that is, the terminal for red light Lr. The pulsation signal p is transmitted to the G terminal with the transmission coefficient 1, and is transmitted to the R terminal with the transmission coefficient φs. The noise signal n is transmitted to the G terminal with the transmission coefficient 1, and is transmitted to the R terminal with the transmission coefficient φn.

  In the signal observation model shown in FIG. 9, when the pulsation signal p and the noise signal n are mixed by the following equation (1), the G signal observed at the G terminal and the R signal observed at the R terminal are obtained. That is, in order to separate the pulsation signal p and the noise signal n, an inverse matrix operation represented by the following equation (2) may be performed. The inverse matrix in Equation (2) is a separation matrix.

  In order to separate the pulsation signal p and the noise signal n using the separation matrix shown in Expression (2), it is necessary to estimate φs and φn. This φs is the norm ratio of the vector of the R signal to the G signal in a stable period that is hardly affected by body movement. Φn is the norm ratio of the vector of the R signal to the G signal during the noise period affected by body movement.

The separation unit 42 calculates the norm ratio of the stable period by the following equation (3). In the formula (3), ‖R _ACpulse ‖ ₂ is the norm of the AC component of the R signal in the stable period, ‖G _ACpulse ‖ ₂ is the norm of the AC component of the G signal in the stable period, ‖R _DCpulse ‖ ₂ is the norm of the DC component of the R signal during the stable period, and ‖G _DCpulse ‖ ₂ is the norm of the DC component of the G signal during the stable period. Further, the separation unit 42 calculates the norm ratio of the noise period by the following equation (4). In the formula (4), ‖R _ACnoise ‖ ₂ is the norm of the AC component of the R signal in the noise period, ‖G _ACnoise ‖ ₂ is the norm of the AC component of the G signal in the noise period, ‖R _DCnoise ‖ ₂ is the norm of the DC component of the R signal in the noise period, and ‖G _DCnoise ‖ ₂ is the norm of the DC component of the G signal in the noise period.

  The separation unit 42 substitutes the norm ratio obtained by the equation (3) as φs and the norm ratio obtained by the equation (4) as φn into the separation matrix of the equation (2), and the G signal measured in the noise period. By substituting the value of the AC component of the R signal into G and R in equation (2), the pulsation component and the noise component in the noise period are separated.

  As described above, the G signal or R signal is mixed with signal noise components that have no correlation with other signals due to the difference in circuit characteristics between the first signal processing unit 24a and the second signal processing unit 24b. Resulting in. However, according to the above-described embodiment, since the signal noise component having a low correlation with the G signal is removed from the R signal in the first removal unit 41, the correlation between the R signal and the G signal becomes high. Thereby, compared with the case where the correlation between G signal and R signal is low, the precision which isolate | separates a pulsation component and a noise component from G signal and R signal in the separation part 42 can be improved.

  The present invention is not limited to the above-described embodiment, and may be modified as follows. Further, the following modifications may be combined with each other.

(1) Modification 1
In the above-described embodiment, the signal noise component having no correlation with the G signal is removed from the R signal. However, contrary to this embodiment, a signal noise component uncorrelated with the R signal may be removed from the G signal. Here, it is assumed that the G signal output from the first A / D converter 23a includes the first signal noise component and the second noise component in addition to the measurement signal component. Further, it is assumed that the R signal output from the second A / D converter 23b includes the first signal noise component in addition to the measurement signal component.

  In this case, the R signal (an example of the first signal) output from the second A / D conversion unit 23 b is input to the delay unit 51. The G signal (an example of the second signal) output from the first A / D conversion unit 23 a is input to the FIR filter 53. As described above, the G signal includes the second signal noise component (an example of the first signal component) that is not included in the R signal. In this case, the FIR filter 53 removes the second signal noise component having no correlation with the R signal from the G signal. As a result, the G signal from which the second signal noise component has been removed is output from the FIR filter 53. Since the G signal includes only the measurement signal component and the first signal noise component, like the R signal, it has a high correlation with the R signal. In this case, the separation unit 42 receives the G signal output from the FIR filter 53 and the R signal output from the second A / D conversion unit 23b. Even with such a configuration, the correlation between the G signal and the R signal can be increased.

(2) Modification 2
In the above-described embodiment, only the R signal is subjected to the process of removing the signal noise component uncorrelated with the G signal. However, processing for removing signal noise components having no correlation with other signals may be performed on both the R signal and the G signal.

  FIG. 10 is a block diagram showing a functional configuration of the CPU 11 according to this modification. The CPU 11 includes a second removal unit 43 in addition to the first removal unit 41 and the separation unit 42 described above. The G signal output from the first A / D conversion unit 23 a and the R signal output from the second A / D conversion unit 23 b are input to both the first removal unit 41 and the second removal unit 43. Is done. Here, it is assumed that the G signal output from the first A / D converter 23a includes the first signal noise component in addition to the measurement signal component. Further, it is assumed that the R signal output from the second A / D converter 23b includes a second noise component in addition to the measurement signal component. When the G signal and the R signal are input, the second removing unit 43 removes a signal component having no correlation with the R signal from the input G signal using an adaptive filter.

  FIG. 11 is a conceptual diagram of an adaptive filter used by the second removal unit 43. This adaptive filter has the same configuration as the adaptive filter of the first removal unit 41 described above. However, the G signal output from the first A / D converter 23a is input to the delay device 61, and the R signal output from the second A / D converter 23b is input to the FIR filter 63. Is done. As described above, the G signal includes the first signal noise component (an example of the second signal component) that has no correlation with the R signal. In this case, the FIR filter 63 removes the first signal noise component that has no correlation with the R signal from the G signal. As a result, the G signal from which the first signal noise component has been removed is output from the FIR filter 63.

  In addition, the first removing unit 41 removes a signal component that has no correlation with the G signal from the input R signal, as described above. As described above, the R signal includes the second signal noise (an example of the first signal component) that has no correlation with the G signal. In this case, the FIR filter 53 removes the second signal noise component having no correlation with the G signal from the R signal. As a result, the R signal from which the second signal noise component has been removed is output from the FIR filter 53.

  Since the G signal output from the FIR filter 63 and the R signal output from the FIR filter 53 both include only the measurement signal component, they have a high correlation. In this case, the G signal output from the FIR filter 63 and the R signal output from the FIR filter 53 are input to the separation unit 42. According to this modification, the correlation between the G signal and the R signal can be enhanced even when both the G signal and the R signal include a signal noise component that has no correlation with other signals.

(3) Modification 3
The light used for pulse wave measurement is not limited to light of two wavelengths. For example, the pulse wave may be measured using light of one wavelength. In this case, the 1st light emission part 19a and the 2nd light emission part 19b irradiate the light of the same wavelength. For example, both the first light emitting unit 19a and the second light emitting unit 19b emit green light. In addition, the first light emitting unit 19a, the second light emitting unit 19b, the first light receiving unit 20a, and the second light receiving unit 20b have a distance between the second light emitting unit 19b and the second light receiving unit 20b. The first light emitting unit 19a and the first light receiving unit 20a are arranged to have the same distance. Even with such a configuration, the correlation between the two signals can be increased by performing the same processing as in the above-described embodiment.

(4) Modification 4
The method of signal separation performed in the separation unit 42 is not limited to the method described in the embodiment. For example, a pulsating component and a noise component may be separated from two signals by applying a method described in Japanese Patent Application Laid-Open No. 2009-261458.

(5) Modification 5
In the adaptive filter described above, the FIR filter 53 is used as the coefficient variable filter. However, the coefficient variable filter used in the adaptive filter is not limited to the FIR filter 53. For example, instead of the FIR filter 53, an IIR (Infinite impulse response) filter may be used.

(6) Modification 6
In the embodiment described above, the first removal unit 41 is realized by a digital filter. However, the first removal unit 41 may be realized by an analog filter. In this case, the 1st removal part 41 removes the 2nd signal component which has no correlation with G signal from the input R signal using an analog filter. Similarly, the second removal unit 43 may also be realized by an analog filter.

(7) Modification 7
The light emitted by the first light emitting unit 19a and the second light emitting unit 19b is not limited to green light and red light. For example, light of other wavelengths such as blue light and infrared light may be used.

(8) Modification 8
In the embodiment which moved up, the 1st light-receiving part 20a which receives green light, and the 2nd light-receiving part 20b which receives red light were provided separately. However, a two-divided photodiode may be used instead of the first light receiving unit 20a and the second light receiving unit 20b.

(9) Modification 9
The apparatus main body 3 and the pulse wave sensor 4 may be connected by wireless communication. Further, the apparatus main body 3 and the pulse wave sensor 4 may be configured integrally. Further, the part to which the pulse wave sensor 4 is attached is not limited to the finger. For example, other parts of the living body such as the back of the hand, wrist, upper arm, back of the foot, earlobe, etc. may be used.

(10) Modification 10
The 1st light-receiving part 20a and the 2nd light-receiving part 20b may receive the light which permeate | transmitted the biological body. In this case, the first light emitting unit 19a and the first light receiving unit 20a, and the second light emitting unit 19b and the second light receiving unit 20b are provided at positions facing each other across the living body. That is, the first light receiving unit 20a and the second light receiving unit 20b may receive light that has passed through the living body. This “passing” is a concept including a case where the light is reflected by a part in the living body and a case where the light passes through the living body.

(11) Modification 11
The program executed in the CPU 11 may be provided in a state of being recorded on a recording medium such as a magnetic tape, a magnetic disk, a flexible disk, an optical disk, a magneto-optical disk, or a memory, and may be installed in the pulse wave measuring device 1. Further, this program may be downloaded to the pulse wave measuring device 1 via a communication line such as the Internet.

DESCRIPTION OF SYMBOLS 1 ... Pulse wave measuring device, 11 ... CPU, 12 ... ROM, 13 ... RAM, 14 ... Display part, 15 ... Operation part, 16 ... Oscillation circuit, 17 ... Time measuring circuit, 18 ... Drive circuit, 19a ... 1st light emission Part, 19b ... second light emitting part, 20a ... first light receiving part, 20b ... second light receiving part, 21a ... first filter part, 21b ... second filter part, 22a ... first amplifier circuit, 22b ... second amplifier circuit, 23a ... first A / D converter, 23b ... second A / D converter, 24a ... first signal processor, 24b ... second signal processor, 41 ... 1st removal part, 42 ... separation part, 43 ... 2nd removal part

Claims (6)

A first irradiation unit that irradiates the living body with the first light;
A second irradiation unit for irradiating the living body with second light;
A first light receiving unit that receives the first light reflected by the living body and converts the received first light into a first signal;
A second light receiving unit that receives the second light reflected by the living body and converts the received second light into a second signal;
A first signal processing unit that performs first signal processing on the first signal;
A second signal processing unit for performing second signal processing on the second signal;
Low There first signal component than the correlation threshold between the first signal processing the first signal subjected, the second signal processing is removed from the second signal subjected, A first removal unit that outputs the second signal from which the first signal component has been removed, and
The first removal unit includes:
A delay unit for delaying the first signal;
An FIR filter that performs filtering on the second signal using a coefficient;
An adder that outputs an error signal indicating a difference between the delay unit and the output signal of the FIR filter;
The pulse wave measuring device, wherein the coefficient in the FIR filter is updated according to the error signal. Removing a second signal component whose correlation with the second signal subjected to the second signal processing is lower than a threshold from the first signal subjected to the first signal processing; The pulse wave measuring apparatus according to claim 1, further comprising: a second removing unit that outputs the first signal from which the second signal component is removed. The first signal subjected to the first signal processing and the second signal from which the first signal component has been removed by the first removal unit, or the second signal by the second removal unit. From the first signal from which the signal component has been removed and the second signal from which the first signal component has been removed by the first removal unit, a pulsation component and a noise component indicating the pulse wave of the living body The pulse wave measuring device according to claim 2 , further comprising a separation unit that separates the two . The pulse wave measuring device according to any one of claims 1 to 3, wherein the first light and the second light have different wavelengths. The first signal processing and the second signal processing include processing for amplifying the first signal or the second signal, or processing for converting an analog signal into a digital signal. 5. The pulse wave measuring device according to any one of 1 to 4. When the living body is irradiated with the first light by the first irradiating unit and the first light reflected by the living body is converted into the first signal by the first light receiving unit, the first signal is changed to the first signal. A first signal processing unit that performs one signal processing;
When the second irradiation unit irradiates the living body with the second light, and the second light receiving unit converts the second light reflected by the living body into a second signal, the second signal is converted into the second signal. A second signal processing unit for performing second signal processing;
Removing a first signal component whose correlation with the first signal subjected to the first signal processing is lower than a threshold value from the second signal subjected to the second signal processing; A first removal unit that outputs the second signal from which the first signal component has been removed, and
The first removal unit includes:
A delay unit for delaying the first signal;
An FIR filter that performs filtering on the second signal using a coefficient;
An adder that outputs an error signal indicating a difference between the delay unit and the output signal of the FIR filter;
The signal processing apparatus, wherein the coefficient in the FIR filter is updated according to the error signal.