JP2011206286A - Apparatus and method for measuring biological information - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for measuring biological information which acquire biological information while reducing noises by simple processing and reducing power consumption.SOLUTION: The apparatus for measuring biological information Sa includes a sensor section 1 for measuring a predetermined physiological phenomenon of a living body which is a measurement object and outputting measurement data, a histogram calculating section 35 for calculating a first histogram on the basis of the measurement data measured by the sensor section 1, and a statistic parameter calculating section 37a for acquiring a predetermined statistic parameter in the first histogram acquired by the histogram calculating section 35. The apparatus for measuring biological information acquires a second histogram on the basis of the first histogram acquired by the histogram calculating section 35 and the predetermined statistic parameter calculated by the statistic parameter calculating section 37a, and acquires predetermined biological information on the basis of the second histogram.

Description

  The present invention relates to a biological information measuring apparatus that measures biological information related to a living body by measuring physiological phenomena of the living body, and in particular, even when noise occurs due to, for example, body movement of the living body, for example, blood oxygen saturation or pulse rate The present invention relates to a biological information measuring device and a biological information measuring method capable of suitably measuring numbers and the like.

  As is well known, the significance of monitoring the oxygen concentration in living tissue is extremely great in clinical practice. Oxygen is the most important substance for maintaining life activity, and biological tissue cells are seriously injured when the supply of oxygen is cut off. Therefore, parameters relating to oxygen supply are considered to be important. For this reason, when oxygen supply can become unstable, for example, when treating patients with anesthesia, post-surgery, respiratory failure and circulatory failure, monitor whether or not oxygen is being supplied appropriately This is very important. This oxygen supply to the living tissue is performed by arterial blood. Therefore, in order to grasp whether or not oxygen supply to the living tissue is appropriately performed, living body information such as a pulse rate and blood oxygen saturation is monitored.

  Conventionally, a biological information measuring device called a pulse oximeter is known as a device for measuring biological information such as the pulse rate and blood oxygen saturation. This biological information measuring device uses a fluctuation component in the amount of transmitted or reflected light of living tissue caused by pulsation of arterial blood, and measures the attenuation of pulsation with two different wavelengths of light, and calculates the oxygen saturation from the ratio. It is a device to seek. In this biological information measuring apparatus, noise is generated due to, for example, body movements of the living body. Therefore, it is necessary to remove or reduce the noise. For example, Patent Documents 1 to 3 disclose apparatuses for removing noise. .

  The pulse photometer disclosed in Patent Document 1 is a light emitting means for irradiating a living tissue with light of two different wavelengths, and light of each wavelength generated from the light emitting means and transmitted or reflected by the living tissue as an electrical signal. The light-receiving means for converting, and the pulse wave data of each wavelength developed in a two-dimensional orthogonal coordinate system with the discrete time-series pulse wave data of the two wavelengths obtained by the light-receiving unit as the vertical axis or the horizontal axis, Using a rotation matrix that rotates at a predetermined angle around the average value of each pulse wave data, a waveform acquisition unit that obtains a waveform obtained by removing noise included in the discrete time-series pulse wave data, and the waveform acquisition unit Waveform analysis means for obtaining the fundamental frequency or pulse rate of the pulse wave by frequency analysis of the obtained waveform, and blood oxygen concentration calculation means for obtaining the oxygen concentration in the blood from the output of the waveform analysis means Eteiru.

  Further, in the devices disclosed in Patent Document 2 and Patent Document 3, the red pulse wave signal Rch obtained by irradiating the biological tissue with red light and the biological tissue obtained by irradiating the biological tissue with infrared light. The obtained infrared pulse wave signal IRch is converted to the frequency domain, and a ratio between the red pulse wave signal Rch and the infrared pulse wave signal IRch in the vicinity of a plurality of peaks in the frequency domain is obtained. And a noise component, a frequency that gives a peak in the pulse wave signal after removing the noise component is obtained, and a pulse rate is obtained from this frequency.

Japanese Patent No. 4352315 US Pat. No. 6,0029,52 US Pat. No. 6,067,462

  By the way, in the apparatus disclosed in Patent Document 1, iterative computation is required to search for a rotation matrix that is optimal for noise removal, and thus the amount of computation processing is relatively large. Moreover, in each apparatus described in Patent Document 2 and Patent Document 3, since Fourier transform is used in the process of converting to the frequency domain, the amount of calculation processing becomes relatively large. As a result, in each of the devices described in Patent Document 1 to Patent Document 3, the amount of calculation processing is relatively large, and thus power consumption increases.

  The present invention has been made in view of the above-described circumstances, and its object is to obtain biological information by simpler processing and to reduce biological power information and biological information measurement. Is to provide a method.

  As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, the biological information measuring device according to one aspect of the present invention is based on a measurement unit that measures a predetermined physiological phenomenon in a living body to be measured and outputs measurement data, and the measurement data measured by the measurement unit. A histogram calculation unit for obtaining a first histogram, a statistical parameter calculation unit for obtaining a predetermined statistical parameter in the first histogram obtained by the histogram calculation unit, a first histogram obtained by the histogram calculation unit, and the statistical parameter calculation And a biological information calculation unit that obtains a second histogram based on the predetermined statistical parameter calculated by the unit and obtains the predetermined biological information based on the second histogram. The biological information measurement method according to one aspect of the present invention is based on a measurement process of measuring a predetermined physiological phenomenon in a measurement target living body and outputting measurement data, and the measurement data measured by the measurement process A histogram calculation step for obtaining a first histogram, a statistical parameter calculation step for obtaining a predetermined statistical parameter in the first histogram obtained by the histogram calculation step, a first histogram obtained by the histogram calculation step, and the statistical parameter calculation A biometric information calculating step of obtaining a second histogram based on the predetermined statistical parameter calculated in the step, and obtaining the predetermined biometric information based on the second histogram.

  In the biological information measuring device and the biological information measuring method configured as described above, the first histogram of the measurement data is obtained, the statistical parameter of the first histogram is obtained, and the second histogram is obtained based on the first histogram and the statistical parameters. And predetermined biological information is obtained based on the second histogram. As described above, the biological information measuring apparatus and the biological information measuring method according to the present invention can obtain biological information by simpler processing, and as a result, can reduce power consumption.

  In another aspect, in the above-described biological information measurement device, preferably, the measurement unit irradiates the biological tissue of the living body with first light having a predetermined first wavelength and transmits the biological tissue of the biological body. Alternatively, the first sensor unit that receives the reflected first light and outputs first measurement data, and irradiates the living tissue of the living body with the second light having a predetermined second wavelength different from the first wavelength, and the living body A sensor unit including a second sensor unit that receives second light transmitted or reflected from the living tissue and outputs second measurement data, wherein the histogram calculation unit is an alternating current for a DC component in the first measurement data. A histogram f (p) of a third ratio p of a first ratio of components and a second ratio of AC components to DC components in the second measurement data is obtained as the first histogram, and the statistical parameter calculation unit The order of The expected value ev in the first histogram f (p) is obtained as a parameter, and when the biological information calculation unit sets g1 (p) = f (2 × ev−p), the third ratio p is the expected value. {G1 (p) -f (p)} / ∫ {g1 (p) -f (p)} dp when the value is larger than the value ev or when g1 (p) -f (p) is larger than 0 Is obtained as the second histogram, and the pulse rate of the living body is obtained based on the second histogram.

  According to this configuration, there is provided a biological information measuring device that obtains the expected value ev of p based on the first histogram f (p) and the pulse rate of the living body based on the second histogram g1 (p).

  In another aspect, in the above-described biological information measurement device, preferably, the measurement unit irradiates the biological tissue of the living body with first light having a predetermined first wavelength and transmits the biological tissue of the biological body. Alternatively, the first sensor unit that receives the reflected first light and outputs first measurement data, and irradiates the living tissue of the living body with the second light having a predetermined second wavelength different from the first wavelength, and the living body A sensor unit including a second sensor unit that receives second light transmitted or reflected from the living tissue and outputs second measurement data, wherein the histogram calculation unit is an alternating current for a DC component in the first measurement data. A histogram f (p) of a third ratio p of a first ratio of components and a second ratio of AC components to DC components in the second measurement data is obtained as the first histogram, and the statistical parameter calculation unit The order of An expected value ev and a moving average g2 (p) in the first histogram f (p) are obtained as parameters, and the biological information calculation unit determines that the third ratio p is greater than the expected value ev, or the g2 {G2 (p) −f (p)} / ∫ {g2 (p) −f (p)} dp when (p) −f (p) is greater than 0 is obtained as the second histogram, The pulse rate of the living body is obtained based on the histogram.

  According to this configuration, the expected value ev of p and the moving average g2 (p) from the first histogram f (p) are obtained as predetermined statistical parameters, and the expected value ev and moving average g2 of the first histogram f (p) are obtained. A biological information measuring device for obtaining the pulse rate of the living body based on (p) is provided.

  In another aspect, in the above-described biological information measurement device, preferably, the measurement unit irradiates the biological tissue of the living body with first light having a predetermined first wavelength and transmits the biological tissue of the biological body. Alternatively, the first sensor unit that receives the reflected first light and outputs first measurement data, and irradiates the living tissue of the living body with the second light having a predetermined second wavelength different from the first wavelength, and the living body A sensor unit including a second sensor unit that receives second light transmitted or reflected from the living tissue and outputs second measurement data, wherein the histogram calculation unit is an alternating current for a DC component in the first measurement data. A histogram f (p) of a third ratio p of a first ratio of components and a second ratio of AC components to a DC component in the second measurement data is obtained as the first histogram, and the statistical parameter calculator is 1 hiss A moving average g2 (p) in the gram f (p) is obtained, a third ratio p_p that gives a peak of the moving average g2 (p) is obtained as the predetermined statistical parameter, and the biological information calculating unit is configured to obtain the third ratio. {g2 (p) −f (p) when p is larger than a third ratio p_p giving the peak of the moving average g2 (p) or when g2 (p) −f (p) is greater than 0 } / ∫ {g2 (p) −f (p)} dp is obtained as the second histogram, and the pulse rate of the living body is obtained based on the second histogram.

  According to this configuration, the moving average g2 (p) of the first histogram f (p) and the third ratio p_p that gives the peak of the moving average g2 (p) are obtained as predetermined statistical parameters, and the first histogram f (p There is provided a biological information measuring device for obtaining the pulse rate of the living body based on the moving average g2 (p) of p).

  In another aspect, in the above-described biological information measuring device, preferably, the biological information calculation unit changes a calculation formula for calculating the pulse rate of the living body according to a standard deviation value of the first histogram. To do.

  According to this configuration, there is provided a biological information measuring device that changes a calculation formula for obtaining the pulse rate of the living body according to the degree of noise included in the measurement data.

  In another aspect, in the above-described biological information measuring device, preferably, the biological information calculation unit further calculates blood oxygen saturation as the predetermined biological information.

  According to this configuration, in addition to the pulse rate, the blood oxygen saturation is also obtained.

  The biological information measuring device and the biological information measuring method according to the present invention can obtain biological information by simpler processing, and as a result, can reduce power consumption.

It is a block diagram which shows the structure of the biometric information measuring apparatus in 1st Embodiment. It is a flowchart which shows operation | movement of the biometric information measuring apparatus in 1st Embodiment. It is a figure for demonstrating operation | movement of the biometric information measuring apparatus in 1st Embodiment. It is a block diagram which shows the structure of the biometric information measuring apparatus in 2nd Embodiment. It is a flowchart which shows operation | movement of the biometric information measuring apparatus in 2nd Embodiment. It is a figure for demonstrating operation | movement of the biometric information measuring apparatus in 2nd Embodiment.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted suitably.

  The biological information measuring apparatus according to the present embodiment obtains a first histogram based on a measurement unit that measures a predetermined physiological phenomenon in a living body to be measured and outputs measurement data, and the measurement data measured by the measurement unit. Calculated by a histogram calculation unit, a statistical parameter calculation unit for obtaining a predetermined statistical parameter in the first histogram obtained by the histogram calculation unit, a first histogram obtained by the histogram calculation unit, and the statistical parameter calculation unit A biometric information calculation unit that obtains a second histogram based on the predetermined statistical parameter and obtains the predetermined biometric information based on the second histogram; Alternatively, the biological information measurement device according to the present embodiment obtains a histogram based on a measurement unit that measures a predetermined physiological phenomenon in a measurement target living body and outputs measurement data, and the measurement data measured by the measurement unit. A histogram calculation unit, a statistical parameter calculation unit for obtaining a predetermined statistical parameter in the histogram obtained by the histogram calculation unit, and a plurality of classes of the histogram based on the predetermined statistical parameter calculated by the statistical parameter calculation unit And a biological information calculation unit for obtaining the predetermined biological information based on the measurement data corresponding to one of the plurality of predetermined ranges. Hereinafter, the biological information measuring apparatus in the present embodiment will be described more specifically.

(First embodiment)
FIG. 1 is a block diagram showing the configuration of the biological information measuring apparatus in the first embodiment. The biological information measuring device Sa in the first embodiment is a device that measures biological information related to a living body by measuring a physiological phenomenon of the living body that is a measurement target. The biological information is, for example, a pulse rate or blood oxygen saturation (blood oxygen concentration). Such biological information can be obtained by using a fluctuation component in the transmitted light amount or reflected light amount of a living tissue caused by pulsation of arterial blood, and the basic principle thereof is a well-known conventional means, for example, 53-026437 and the like.

  For example, as shown in FIG. 1, such a biological information measuring device Sa measures a predetermined physiological phenomenon of a living body and outputs measurement data, and the measurement data measured by the sensor unit 1. Based on, for example, a calculation control unit 3a that obtains biological information such as a pulse rate and blood oxygen saturation, and a display unit 5 that displays the biological information measured by the calculation control unit 3a so as to be recognized from the outside. .

  The sensor unit 1 is connected to the calculation control unit 3a, and in this embodiment, is a device that measures information related to blood in a living tissue as a physiological phenomenon of the living body. More specifically, the sensor unit 1 is a device that measures a fluctuation component in a transmitted light amount or a reflected light amount of a living tissue caused by arterial blood pulsation due to a heartbeat as a physiological phenomenon of the living body.

  As a method for measuring the physiological phenomenon of the living body, for example, a method using the light absorption characteristic of hemoglobin in the living tissue can be mentioned. Oxygen is transported to each cell of the living body by hemoglobin, but hemoglobin combines with oxygen in the lung to become oxygenated hemoglobin, and returns to hemoglobin (reduced hemoglobin) when oxygen is consumed in the cells of the living body. Blood oxygen saturation is defined as the percentage of oxyhemoglobin in the blood (in the blood). The absorbance of each of these hemoglobin and oxyhemoglobin has a wavelength dependency, and hemoglobin absorbs more light than oxyhemoglobin for red light (red wavelength region light), for example, while infrared light (infrared light) Less light is absorbed than oxyhemoglobin. In other words, when hemoglobin is oxidized to oxygenated hemoglobin, the absorption of red light decreases and the absorption of infrared light increases. Conversely, when it is reduced to return to hemoglobin, the absorption of red light increases and the absorption of infrared light increases. It has an optical property that absorption is reduced. The biological information measuring device Sa according to the present embodiment uses such a difference in absorption characteristics of hemoglobin and oxyhemoglobin with respect to red light and infrared light, for example, a living body such as a pulse rate and blood oxygen saturation. It seeks information. That is, the greater the absorbance of red light, the greater the amount of reduced hemoglobin and the lower the oxygen saturation. On the contrary, the greater the absorbance of infrared light, the greater the amount of oxyhemoglobin and the greater the oxygen saturation.

  Due to such a method, the sensor unit 1 according to the present embodiment includes, for example, a first sensor unit 11 that measures the light absorption characteristics in the biological tissue with respect to red light, and a first sensor that measures the light absorption characteristics in the biological tissue with respect to infrared light. 2 sensor section 12 and is connected to calculation control section 3a. The first sensor unit 11 includes, for example, an R light emitting element such as a light emitting diode that irradiates the biological tissue with red light having a wavelength λ1, and red light that is irradiated by the R light emitting element and transmitted or reflected by the biological tissue. For example, the second sensor unit 12 is configured to irradiate the living tissue with infrared light having a wavelength λ2 different from the wavelength λ1, for example, a light-emitting diode. An IR light emitting element and an IR light receiving element such as a silicon photodiode that receives infrared light irradiated by the IR light emitting element and transmitted or reflected by the living tissue are configured. The sensor unit 1 can use such a transmission type or reflection type sensor.

  The sensor unit 1 has a structure that can be set in a predetermined biological tissue, such as a finger, an earlobe, or the back of the hand, wrist, or foot of an infant, and is set in the predetermined biological tissue. The measurement data measured by the first and second sensor units 11 and 12 are output to the arithmetic control unit 3a. More specifically, in the first sensor unit 11 having such a configuration, the R light emitting element emits red light to the living tissue, and the R light receiving element is applied to the living tissue by the R light emitting element. The red light R that is transmitted or reflected through the living tissue of the irradiated red light is received, and the received red light is photoelectrically converted, whereby an electric signal corresponding to the amount of received light is used as the measurement data as the operation control unit 3a. Output to. Similarly, in the second sensor unit 12, the IR light emitting element irradiates the biological tissue with infrared light, and the IR light receiving element emits infrared light irradiated onto the biological tissue by the IR light emitting element. Infrared light transmitted or reflected through the living tissue is received, and the received infrared light is photoelectrically converted to output an electrical signal corresponding to the amount of received light to the arithmetic control unit 3a as the measurement data.

  The arithmetic control unit 3a is connected to the display unit 5 and is a device that obtains biological information based on measurement data measured by the sensor unit 1 and controls the entire biological information measuring device Sa. The arithmetic control unit 3a acquires time-series data of measurement data from the sensor unit 1 by sampling the measurement data measured by the sensor unit 1 at a predetermined sampling period (for example, a frequency of 37.5 Hz, for example). is there. Further, for example, the calculation control unit 3a acquires measurement data from the sensor unit 1 as time-series data by driving the sensor unit 1 with a predetermined cycle, that is, by causing each operation of light emission and light reception to be performed. Further, for example, the sensor unit 1 measures the measurement data as time series data from the living tissue by sampling at a predetermined sampling period, and outputs the measurement data of the time series data to the arithmetic control unit 3a. The measurement data may be analog data, but in the present embodiment, the measurement data is digital data. Conversion from analog data to digital data (AD conversion) is performed by the sensor unit 1 or the arithmetic control unit 3a. Further, if necessary, the sensor unit 1 or the operation control unit 3a may further include an amplification unit that amplifies the measurement data before AD conversion.

  More specifically, the arithmetic control unit 3a obtains a first histogram based on measurement data measured by the sensor unit 1, obtains predetermined statistical parameters in the obtained first histogram, and obtains these. A second histogram is obtained based on the first histogram and a predetermined statistical parameter, and the predetermined biological information is obtained based on the second histogram. In other words, the arithmetic control unit 3a obtains a histogram based on the measurement data measured by the sensor unit 1, obtains a predetermined statistical parameter in the obtained histogram, and based on the obtained predetermined statistical parameter. The histogram class is divided into a plurality of predetermined ranges, and the predetermined biological information is obtained based on the measurement data (measurement data of the second histogram) corresponding to one of the plurality of predetermined ranges. . Such an arithmetic control unit 3a is constituted by, for example, a microcomputer including a microprocessor, a memory, and its peripheral circuits. The memory includes various programs such as a biological information calculation program for obtaining biological information based on measurement data measured by the sensor unit 1, a control program for controlling the entire biological information measuring device Sa, and a sensor unit. For example, an EEPROM (Electrically Erasable Programmable Read Only Memory), which is a rewritable nonvolatile memory element, or a nonvolatile memory that stores various data such as the measurement data measured in Step 1 and data necessary for the execution of the program. A ROM (Read Only Memory) which is an element, and a RAM (Random Access Memory) which is a so-called working memory of the microprocessor, for example, which is a volatile storage element, is configured. Central Processing Unit), etc., and functions by executing the program In addition, for example, a first pre-processing unit 31, a second pre-processing unit 32, a first band-pass filter unit (first BPF unit) 33, a second band-pass filter unit (second BPF unit) 34, and a histogram calculation Unit 35, ratio calculation unit 36, statistical parameter calculation unit 37 a, pv calculation unit 38 a, blood oxygen saturation calculation unit 39, pulse rate calculation unit 40, and reliability calculation unit 41.

The first and second preprocessing units 31 and 32 perform predetermined preprocessing on the measurement data input from the sensor unit 1. More specifically, the first preprocessing unit 31 performs so-called dark processing for correcting dark current in the R light receiving element on the measurement data related to red light input from the first sensor unit 11. Then, the first ratio (red light _AC / DC ratio) R (= R _AC / R _DC ) of the _AC component R _AC to the DC component R _DC is calculated, and the first BPF unit 33 is notified (output). ) The first ratio R is considered to be equal to the change in absorbance of the living tissue with respect to red light, based on the approximation by Lambert-Beer law. The second preprocessing unit 32 performs a so-called dark process for correcting dark current in the IR light receiving element on the measurement data related to the infrared light input from the second sensor unit 12, and A second ratio (infrared light _AC / DC ratio) IR (= IR _AC / IR _DC ) of the _AC component IR _AC with respect to the DC component IR _DC is calculated, and this second ratio IR is notified (output) to the first BPF unit 33. . This second ratio IR is considered to be equal to the change in absorbance of the living tissue with respect to infrared light based on the approximation by the Lambert-Beer law. For the dark process, known conventional means are used. For example, an output value (dark current value) Rdark output from the light-receiving R light receiving element is subtracted from the measurement data related to the red light, and the infrared light is subtracted. This is performed by subtracting the output value (dark current value) IRdark output from the IR light receiving element in the light-shielded state from the measurement data related to. The output values Rdark and IRdark output from the light-receiving R light-receiving element and the IR light-receiving element are measured in advance. For example, the output values Rdark and IRdark output from the R light receiving element and the IR light receiving element in the light shielding state may be measured in advance every measurement, or may be measured and stored in advance, for example. .

  The first and second BPF units 33 and 34 are filters that remove a predetermined noise component from the measurement data measured by the sensor unit 1, and are usually included as fluctuation components in the amount of transmitted or reflected light of living tissue caused by pulsation of arterial blood. The frequency components other than the frequency components to be removed are removed. The first BPF unit 33 is, for example, a filter that uses a predetermined frequency band including a frequency component that is normally included as a fluctuation component in the transmitted light amount or reflected light amount of biological tissue caused by pulsation of arterial blood with respect to red light. 1 ratio R is filtered (filtered), and the first ratio R after the filtering process is sent to each of the ratio calculating section 36, blood oxygen saturation calculating section 39, pulse rate calculating section 40, and reliability calculating section 41. Notice. The second BPF unit 34 is, for example, a filter having a predetermined frequency band including a frequency component that is normally included as a fluctuation component in a transmitted light amount or a reflected light amount of living tissue caused by pulsation of arterial blood with respect to infrared light as a pass band, The second ratio IR is filtered (filtered), and the second ratio IR after the filter processing is subjected to the ratio calculation unit 36, the blood oxygen saturation calculation unit 39, the pulse rate calculation unit 40, and the reliability calculation unit 41. To notify.

  The ratio calculation unit 36 calculates a third ratio (two-wavelength variation ratio) p (= R / IR) of the first ratio R with respect to the second ratio IR, and notifies the histogram calculation unit 35 of the third ratio p. It is.

  The histogram calculator 35 calculates a first histogram (frequency distribution) f (p) of the third ratio p obtained from the measurement data measured by the sensor unit 1 within a predetermined time range, and this third ratio p The first histogram f (p) is notified to each of the statistical parameter calculation unit 37a and the pv calculation unit 38a. The predetermined time range is a time range in which the number of pieces of measurement data in which the first histogram f (p) is statistically significant can be acquired. The number of pieces of measurement data is, for example, 300 or 400 Or 500 mag. The histogram calculation unit 35 classifies a predetermined range assumed as a numerical range that can be taken by the third ratio p into a plurality of classes (classes) at predetermined intervals, and the first histogram f (p ), The frequency of the third ratio p in each class by allocating each of the plurality of third ratios p input from the ratio calculation unit 36 to the one of these classes by the predetermined time before Ask for. Thereby, the histogram calculation unit 35 obtains the first histogram f (p) of the third ratio p.

The statistical parameter calculator 37a calculates a predetermined statistical parameter for the first histogram f (p) of the third ratio p calculated by the histogram calculator 35, and uses the calculated statistical parameter as the pv calculator 38a and the blood This is notified to each part of the medium oxygen saturation calculating unit 39. In the present embodiment, the predetermined statistical parameter is an expected value ev and a standard deviation σ of the first histogram f (p). The expected value ev is calculated by the following equation A1.
Expected value ev = ∫p × f (p) dp (A1)
However, the integral ∫ is executed from the minimum class value a to the maximum class value b in the plurality of classes.

  Then, the statistical parameter calculation unit 37a obtains a function g1 (p) = f (2 × ev−p) using the calculated expected value ev.

  The pv calculation unit 38a converts the third ratio p into the signal component ratio pa and the noise component ratio pv based on the statistical parameter in the first histogram f (p) of the third ratio p calculated by the statistical parameter calculation unit 37. In this case, the noise component ratio pv is calculated, and the calculated noise component ratio pv is notified to each of the blood oxygen saturation calculator 39 and the pulse rate calculator 40.

Here, when measuring the absorbance of a living tissue, when the signal component corresponding to the change in absorbance is s and the noise component superimposed on this signal component is n, the first ratio R and the second ratio IR are The following formulas B1 and B2 hold.
IR = s + n (B1)
R = s × pa + n × pv (B2)

  The signal component ratio pa is a ratio between the signal component s corresponding to the change in absorbance in infrared light and the signal component corresponding to the change in absorbance in red light. This signal component ratio pa is generally the oxygen saturation level in blood. It is known to correspond one-to-one. The noise component ratio pv is a ratio between the noise component n superimposed on the signal component s for infrared light and the noise component superimposed on the signal component for red light.

More specifically, in this embodiment, the pv calculation unit 38a is based on the first histogram f (p) obtained by the histogram calculation unit 35 and the predetermined statistical parameter calculated by the statistical parameter calculation unit 37a. A second histogram h1 (p) is obtained, and the noise component ratio pv is calculated using the second histogram h1 (p). In this embodiment, when the function g1 (p) = f (2 × ev−p) is defined, when p ≦ expected value ev, h1 (p) = 0 is defined, and when p> expected value ev, h1 (p) = {g1 (p) −f (p)} / ∫ {g1 (p) −f (p)} dp, and when g1 (p) −f (p) ≦ 0, h1 (p ) = 0 and g1 (p) −f (p)> 0, h1 (p) = {g1 (p) −f (p)} /｝ {g1 (p) −f (p)} dp Is defined. That is,
h1 (p) = 0; p ≦ expected value ev or g1 (p) −f (p) ≦ 0
h1 (p) = {g1 (p) −f (p)} / ∫ {g1 (p) −f (p)} dp (where the integral ∫ is the maximum from the minimum class value a in the plurality of classes. Up to class value b, except for p ≦ ev and g1 (p) −f (p) ≦ 0, p); p> expected value ev or g1 (p) −f (p )> 0 (A2)
The noise component ratio pv is calculated by the following equation A3.
Noise component ratio pv = ∫p × h1 (p) dp (A3)
However, the integral ∫ is executed from the minimum class value a to the maximum class value b in the plurality of classes.

The blood oxygen saturation calculation unit 39 estimates the oxygen saturation based on the noise component ratio pv calculated by the pv calculation unit 38a, for example, the estimated value SvO _{2 of} venous blood oxygen saturation or the oxygen saturation of arterial blood. The value SpO ₂ is obtained, and the obtained oxygen saturations SvO ₂ and SpO ₂ are output to the display unit 5.

More specifically, for example, the blood oxygen saturation calculation unit 39 uses a lookup table (calibration table) representing a relationship between the noise component ratio pv and the oxygen saturation, which is obtained and stored in advance. Then, an estimated value SvO ₂ of oxygen saturation of venous blood is obtained. Further, the blood oxygen saturation calculating unit 39 calculates the signal component ratio pa based on the noise component ratio pv, for example, by using the following equation B3, and the signal component ratio pa obtained and stored in advance. The estimated value SpO ₂ of the arterial blood oxygen saturation is obtained by using a look-up table (calibration table) representing the relationship between the oxygen saturation and the oxygen saturation.
pa = {pv × ΣR (i) × IR (i) −ΣR (i) × R (i)} / {pv × ΣIR (i) × IR (i) −ΣR (i) × IR (i)} .. (B3)

  The pulse rate calculation unit 40 calculates the pulse rate within a predetermined time based on the first ratio R related to red light, the second ratio IR related to infrared light, and the noise component ratio pv calculated by the pv calculation unit 38a. (For example, the pulse rate for 1 minute) is calculated, and this pulse rate is output to the display unit 5.

  More specifically, the pulse rate calculation unit 40 includes the first ratio R (i) related to red light, the second ratio IR (i) related to infrared light, and the noise component calculated by the pv calculation unit 38a. Using the ratio pv, a pulse wave signal S (i) = R (i) −pv × IR (i) is obtained, a period T_period of the signal S (i) is obtained, and a period T_period of the signal S (i) is obtained. The pulse rate (= 60 / period T_period) is obtained by dividing 60 by.

  The reliability calculation unit 41 calculates a predetermined reliability and outputs the calculated reliability to the display unit 5.

The reliability is an index (degree) indicating how reliable the calculated value related to biological information is. Such reliability can be obtained by, for example, any one of the following formulas C1 to C6, and the reliability calculation unit 41 includes the first ratio R related to red light and the second ratio related to infrared light. Based on the ratio IR, a predetermined reliability for the oxygen saturation calculated by the blood oxygen saturation calculating unit 39 is calculated. In the reliability z obtained by such an equation, the reliability of the blood oxygen saturation level decreases as the absolute value of the value z increases. In each of these equations, Σ calculates the sum for i.
z = [Σ {R (i) × IR (i)} / Σ {IR (i)} ² ] − [Σ {R (i)} ² / ΣR {(i) × IR (i)}]・ (C1)
z = [Σ {R (i) × IR (i)} / Σ {IR (i)} ² ] ² − [Σ {R (i)} ² / Σ {IR (i)} ² ] ( C2)
z = [Σ {R (i)} ² / Σ {R (i) × IR (i)}] ² − [Σ {R (i)} ² / (Σ {IR (i)} ² ]... (C3)
z = [(1 / N) × ΣR (i) / IR (i)] ² − (Σ {R (i)} ² ) / (Σ {IR (i)} ² ) (C4)
z = (ΣR (i) × IR (i)) / (Σ {IR (i)} ² ) − (1 / N) × ΣR (i) / IR (i) (C5)
z = (Σ {R (i)} ² ) / (ΣR (i) × IR (i)) − (1 / N) × ΣR (i) / IR (i) (C6)

  The display unit 5 is a device that displays the operating state of the biological information measuring device Sa, biological information obtained by the arithmetic control unit 3a, and the like, and is, for example, a liquid crystal display device (LCD) or an organic EL display device. In the present embodiment, for example, the display unit 5 displays the pulse rate display unit 51 that displays the pulse rate calculated by the pulse rate calculation unit 40 and the oxygen saturation calculated by the blood oxygen saturation calculation unit 39. The blood oxygen saturation level display unit 52 and the reliability level display unit 53 that displays the reliability level calculated by the reliability level calculation unit 41 are provided.

  Next, the operation of the biological information measuring device Sa of the first embodiment will be described. FIG. 2 is a flowchart showing the operation of the biological information measuring apparatus in the first embodiment. FIG. 3 is a diagram for explaining the operation of the biological information measuring apparatus according to the first embodiment. The relatively thick solid line in FIG. 3 indicates the histogram f (p) of the third ratio p, the broken line indicates the function g1 (p) (= f (2 × ev−p)), and the relatively thin solid line indicates Represents the second histogram h1 (p).

  In the biological information measuring apparatus Sa of the present embodiment, for example, measurement of biological information of a biological object to be measured is started by turning on a power switch (not shown) or turning on a measurement start switch after turning on the power switch, Measurement data is acquired and a first histogram f (p) is created.

  More specifically, first, the measurement data Rs (including the dark current) relating to the red light and the dark current Rdark are measured by the first sensor unit 11 of the sensor unit 1 and converted from an analog signal to a digital signal. At the same time, the second sensor unit 12 of the sensor unit 1 measures the measurement data IRs (including the dark current) related to the infrared light and the dark current IRdark, and converts them from an analog signal to a digital signal. Subsequently, dark processing (Rs-Rdark) is performed on the measurement data Rs related to red light input from the sensor unit 1 by the first preprocessing unit 31 of the arithmetic control unit 3a, and the first ratio R is calculated. In addition, dark processing (IRs-IRdark) is performed on the measurement data IRs related to the infrared light input from the sensor unit 1 by the second preprocessing unit 32 of the arithmetic control unit 3a, and the second ratio IR Is calculated. Subsequently, the first ratio R notified from the first preprocessing unit 31 is filtered by the first BPF unit 33 of the calculation control unit 3a, and the second preprocessing unit is filtered by the second BPF unit 34 of the calculation control unit 3a. The second ratio IR notified from 32 is filtered. Subsequently, a third ratio p of the first ratio R with respect to the second ratio IR is calculated by the ratio calculation unit 36 of the calculation control unit 3a, and the histogram calculation unit 35 of the calculation control unit 3a calculates the third ratio p in a predetermined time range. A histogram f (p) of 3 ratio p is calculated. For example, the histogram f (p) of the third ratio p as shown by the solid line in FIG. 3 is obtained for the measurement data in the time range from the current time ti to the past time ti− (N + 1).

  When the first histogram f (p) of the third ratio p is created in this way, in FIG. 2, first, in step S11, the statistical parameter calculation unit 37a of the calculation control unit 3a has a predetermined range, for example, the first The expected value ev and standard deviation σ for the histogram f (p) of the third ratio p are calculated in the range from the minimum class value a to the maximum class value b in the class of one histogram f (p).

  Subsequently, in step S12, the arithmetic control unit 3a determines whether or not the obtained standard deviation σ is equal to or smaller than a predetermined value σth (whether σ ≦ σth?). This step S12 is a process for determining the degree of noise included in the first histogram f (p) of the third ratio p, and the predetermined value σth is set as a threshold without performing a noise removal process described later. From the viewpoint of whether or not the pulse rate can be obtained from the measurement data with a predetermined accuracy according to the specification, for example, it is set appropriately.

  If the standard deviation σ is equal to or smaller than the predetermined value σth as a result of the determination in step S12 (Yes), the process of step S22 is executed, while the standard deviation σ is determined to be the predetermined value σth as a result of the determination in step S12. If not (No), the process of step S13 is executed.

  In step S13, the statistical parameter calculation unit 37a calculates g1 (p) (= f (2 × ev−p)). For example, in the above example, g1 (p) indicated by a broken line in FIG. 3 is obtained with respect to the first histogram f (p) having the third ratio p indicated by a solid line in FIG.

  Subsequently, in step S14, the pv calculation unit 38a of the calculation control unit 3a determines whether or not the third ratio p is equal to or higher than the expected value ev (p ≧ ev?). As a result of the determination in step S14, when the third ratio p is not equal to or greater than the expected value ev (No, p <ev), the pv calculation unit 38a executes step S16, and h1 ( p) = 0, and the process of step S19 is executed. On the other hand, as a result of the determination in step S14, when the third ratio p is equal to or greater than the expected value ev (Yes, p ≧ ev), the pv calculation unit 38a executes step S15, and g1 (p) −f It is determined whether (p) is 0 or more (whether g1 (p) −f (p) ≧ 0).

  If g1 (p) -f (p) is not equal to or greater than 0 as a result of the determination in step S15 (No, g1 (p) -f (p) <0), the pv calculation unit 38a performs step S17. And h1 (p) = 0 for the third ratio p, and the process of step S19 is executed. On the other hand, if g1 (p) −f (p) is 0 or more as a result of the determination in step S15 (Yes, g1 (p) −f (p) ≧ 0), the pv calculation unit 38a S18 is executed, and h1 (p) = {g1 (p) −f (p)} / ∫ {g1 (p) −f (p)} dp for the third ratio p (provided that the integral ∫ Is performed from the minimum class value a to the maximum class value b in the class (except for the p region where p ≦ ev and g1 (p) −f (p) ≦ 0).

  Each process from step S14 to step S18 is executed for each of the third ratios p in the range of a ≦ p ≦ b, and the second histogram h1 (p) is obtained. For example, in the above-described example, the second histogram h1 (p) indicated by the relatively thin solid line in FIG. 3 is obtained with respect to the first histogram f (p) having the third ratio p indicated by the relatively thick solid line in FIG. .

  In step S19, the pv calculation unit 38a determines that the noise component ratio pv = ∫p × h1 (p) dp (where the integral ∫ is the minimum class value a to the maximum class value b in the plurality of classes). Will be executed by.)

  Subsequently, in step S20, the pulse rate calculator 40 uses the noise component ratio pv obtained by the above-described processes to obtain a pulse wave signal S (i) = R (i) −pv × IR (i). The period T_period of the signal S (i) is obtained.

  Subsequently, in step S21, the pulse rate calculation unit 40 calculates the pulse rate (= 60 / period T_period) by dividing 60 by the period T_period of the signal S (i) thus determined.

  On the other hand, in step S22, the pulse rate calculation unit 40 obtains the cycle T_period of the second ratio IR (i), and subsequently executes step S21, and thus obtains the cycle T_period of the second ratio IR (i) thus obtained. The pulse rate (= 60 / period T_period) is obtained by dividing 60 by.

If σ is equal to or smaller than the predetermined value σth, the process may jump to step S20 as pv = [Σ {R (i) × IR (i)} / Σ {IR (i)} ² ] + δ. Here, δ is a positive value, may be a constant value, or may be a value according to [Σ {R (i) × IR (i)} / Σ {IR (i)} ² ].

  Then, the arithmetic control unit 3 a displays the pulse rate obtained by each of these processes on the pulse rate display unit 51 of the display unit 5.

  In the above-described processing, the integration range for obtaining the expected value ev and the integration range for obtaining the noise component ratio pv may be the same or different.

Further, the blood oxygen saturation calculation unit 39 of the calculation control unit 3a calculates the venous blood oxygen saturation SvO ₂ based on the noise component ratio pv, and calculates the signal component ratio pa based on the noise component ratio pv. Based on the obtained signal component ratio pa, the oxygen saturation SpO ₂ of arterial blood is obtained. Then, the arithmetic control unit 3 a displays the obtained oxygen saturation SvO ₂ and SpO ₂ on the blood oxygen saturation display unit 52 of the display unit 5.

  Further, the reliability calculation unit 41 of the calculation control unit 3 a obtains a predetermined reliability, and the calculation control unit 3 a displays the obtained reliability on the reliability display unit 53 of the display unit 5.

  As described above, in the biological information measuring device Sa of the present embodiment, the first histogram f (p) of the third ratio p based on the measurement data R and IR is obtained, and an expected value is used as a statistical parameter of the first histogram f (p). ev is obtained, and predetermined biological information is obtained based on measurement data in a predetermined range based on the expected value ev. As described above, the biological information measuring device Sa of the present embodiment can obtain the biological information by simpler processing, and as a result, can reduce power consumption.

  In this embodiment, the expected value ev in the first histogram f (p) of the third ratio p is obtained as a predetermined statistical parameter, and the pulse of the living body is based on the expected value ev of p based on the first histogram f (p). A biological information measuring device Sa for obtaining the number and further obtaining the blood oxygen saturation is provided.

  Next, another embodiment will be described.

(Second Embodiment)
The biological information measuring apparatus Sa according to the first embodiment uses the expected value ev and the function g1 (p) = f (2 × ev−p) in the first histogram f (p) with the third ratio p, and the pulse rate and blood The biological oxygen measurement device Sb in the second embodiment calculates the intermediate oxygen saturation, but the expected value ev in the first histogram f (p) of the third ratio p and the moving average g2 (p) of the third ratio p. Is used to determine the pulse rate and blood oxygen saturation.

  FIG. 4 is a block diagram showing the configuration of the biological information measuring device in the second embodiment. In FIG. 4, the biological information assumption device Sb according to the second embodiment includes a sensor unit 1, an arithmetic control unit 3 b, and a display unit 5. Since the sensor unit 1 and the display unit 5 in the biological information assumption device Sb of the second embodiment are the same as the sensor unit 1 and the display unit 5 in the biological information assumption device Sa of the first embodiment, respectively, description thereof is omitted. To do.

  And the calculation control part 3b in the biometric information assumption apparatus Sb of 2nd Embodiment is connected to the display part 5, and while calculating | requiring biometric information based on the measurement data measured by the sensor part 1, the biometric information measurement apparatus Sa whole Functionally, for example, a first pre-processing unit 31, a second pre-processing unit 32, a first band-pass filter unit (first BPF unit) 33, and a second band-pass filter unit (Second BPF unit) 34, histogram calculation unit 35, ratio calculation unit 36, statistical parameter calculation unit 37b, pv calculation unit 38b, blood oxygen saturation calculation unit 39, pulse rate calculation unit 40, A reliability calculation unit 41; The first preprocessing unit 31, the second preprocessing unit 32, the first BPF unit 33, the second BPF unit 34, the histogram calculation unit 35, the ratio calculation unit 36, and the blood oxygen saturation in the biological information assumption device Sb of the second embodiment. The calculation unit 39, the pulse rate calculation unit 40, and the reliability calculation unit 41 are respectively a first preprocessing unit 31, a second preprocessing unit 32, a first BPF unit 33, and a first BPF unit 33 in the biological information assumption device Sa of the first embodiment. Since it is similar to the 2BPF unit 34, the histogram calculation unit 35, the ratio calculation unit 36, the blood oxygen saturation calculation unit 39, the pulse rate calculation unit 40, and the reliability calculation unit 41, description thereof is omitted.

  The statistical parameter calculator 37b calculates a predetermined statistical parameter for the first histogram f (p) of the third ratio p calculated by the histogram calculator 35, and uses the calculated statistical parameter as the pv calculator 38b and the blood This is notified to each part of the medium oxygen saturation calculating unit 39. In the present embodiment, the predetermined statistical parameter is the moving average g2 (p) of the first histogram f (p) related to the expected value ev, the standard deviation σ, and the third ratio p in the first histogram f (p).

  The pv calculation unit 38b calculates a noise component ratio pv based on the first histogram f (p) of the third ratio p obtained by the histogram calculation unit 35, and uses the calculated noise component ratio pv for blood oxygen saturation. It notifies to each part of the degree calculation part 39 and the pulse rate calculation part 40.

More specifically, in this embodiment, the pv calculator 38b is based on the first histogram f (p) obtained by the histogram calculator 35 and the predetermined statistical parameter calculated by the statistical parameter calculator 37a. A second histogram h2 (p) is obtained, and the noise component ratio pv is calculated using the second histogram h2 (p). In this embodiment, when p ≦ expected value ev, h2 (p) = 0 is defined, and when p> expected value ev, h2 (p) = {g2 (p) −f (p)} / ∫ {g2 ( p) −f (p)} dp, h2 (p) = 0 is defined when g2 (p) −f (p) ≦ 0, and h2 when g2 (p) −f (p)> 0. (P) = {g2 (p) −f (p)} / ∫ {g2 (p) −f (p)} dp. That is,
h2 (p) = 0; p ≦ expected value ev or g2 (p) −f (p) ≦ 0
h2 (p) = {g2 (p) −f (p)} / ∫ {g2 (p) −f (p)} dp (where the integral ∫ is the maximum from the minimum class value a in the plurality of classes. Up to the value b of the class of ## EQU2 ## except for p ≦ ev and g1 (p) −f (p) ≦ 0, where p> expected value ev or g2 (p) −f (p )> 0 (A4)
The noise component ratio pv is calculated by the following equation A5.
Noise component ratio pv = ∫p × h2 (p) dp (A5)
However, the integral ∫ is executed from the minimum class value a to the maximum class value b in the plurality of classes.

  Next, the operation of the biological information measuring device Sb of the second embodiment will be described. FIG. 5 is a flowchart showing the operation of the biological information measuring apparatus in the second embodiment. FIG. 6 is a diagram for explaining the operation of the biological information measuring apparatus according to the second embodiment. The relatively thick solid line in FIG. 6 indicates the histogram f (p) of the third ratio p, the broken line indicates the moving average g2 (p) of the histogram f (p) with respect to the third ratio p, and the relatively thin solid line indicates , Represents the function h2 (p).

  In the biological information measuring device Sb of the present embodiment, similarly to the biological information measuring device Sa of the first embodiment, for example, by turning on a power switch (not shown) or turning on a measurement start switch (not shown) after turning on the power switch, Measurement of biological information of a living body to be measured is started, measurement data is acquired, and a first histogram f (p) is created. For example, for the measurement data in the time range from the current time ti to the past time ti− (N + 1), the first histogram f (p) having the third ratio p as shown by the solid line in FIG. 6 is obtained.

  When the first histogram f (p) of the third ratio p is created, in FIG. 5, first, in step S31, the statistical parameter calculation unit 37 of the calculation control unit 3b performs a predetermined range as in step S11. For example, the expected value ev and the standard deviation for the first histogram f (p) of the third ratio p in the range from the minimum class value a to the maximum class value b in the class of the first histogram f (p). Each σ is calculated.

  Subsequently, in step S32, the arithmetic control unit 3b determines whether or not the obtained standard deviation σ is equal to or less than a predetermined value σth set in advance (step σ ≦ σth?), As in step S12.

  If the standard deviation σ is equal to or smaller than the predetermined value σth as a result of the determination in step S32 (Yes), the process of step S42 is executed, while the standard deviation σ is determined to be the predetermined value σth as a result of the determination in step S32. If not (No), the process of step S33 is executed.

  In step S33, the statistical parameter calculator 37b moves the moving average g2 (p) = ∫f (p) dp of the first histogram f (p) with respect to the third ratio p (where the integral ∫ is 2ΔP from the current time point). (Executed in the range from p−Δp to p + Δp). For example, in the above example, g2 (p) indicated by a broken line in FIG. 6 is obtained with respect to the first histogram f (p) having the third ratio p indicated by a solid line in FIG.

  Subsequently, in step S34, the pv calculation unit 38b of the arithmetic control unit 3b determines whether or not the third ratio p is equal to or larger than the expected value ev (p ≧ ev?). As a result of the determination in step S34, when the third ratio p is not equal to or greater than the expected value ev (No, p <ev), the pv calculation unit 38b executes step S36, and h2 ( p) = 0, and the process of step S39 is executed. On the other hand, if the result of determination in step S34 is that the third ratio p is equal to or greater than the expected value ev (Yes, p ≧ ev), the pv calculation unit 38b executes step S35, and g2 (p) −f It is determined whether (p) is 0 or more (whether g2 (p) −f (p) ≧ 0).

  If g2 (p) -f (p) is not equal to or greater than 0 as a result of the determination in step S35 (No, g2 (p) -f (p) <0), the pv calculation unit 38b performs step S37. And h2 (p) = 0 for the third ratio p, and the process of step S39 is executed. On the other hand, if g2 (p) −f (p) is equal to or greater than 0 as a result of the determination in step S35 (Yes, g2 (p) −f (p) ≧ 0), the pv calculation unit 38b S38 is executed, h2 (p) = {g2 (p) −f (p)} / ∫ {g2 (p) −f (p)} dp for the third ratio p (where integral ∫ Is performed from the minimum class value a to the maximum class value b in the class (except for the p region where p ≦ ev and g1 (p) −f (p) ≦ 0).

  Each processing from step S34 to step S38 is executed for each of the third ratios p in the range of a ≦ p ≦ b, and the second histogram h2 (p) is obtained. For example, in the above-described example, the second histogram h2 (p) indicated by the relatively thin solid line in FIG. 6 is obtained with respect to the first histogram f (p) having the third ratio p indicated by the relatively thick solid line in FIG. .

  In step S39, the pv calculator 38b determines that the noise component ratio pv = ∫p × h2 (p) dp (where the integral ∫ is the minimum class value a to the maximum class value b in the plurality of classes). Will be executed by.)

  Subsequently, in step S40, the pulse rate calculation unit 40 uses the noise component ratio pv obtained by each of the above-described processes, similarly to step S20, to detect a pulse wave signal S (i) = R (i) −pv. XIR (i) is obtained, and the period T_period of the signal S (i) is obtained.

  Subsequently, in step S41, the pulse rate calculation unit 40 divides 60 by the period T_period of the signal S (i) obtained in this way, similarly to step S21, thereby dividing the pulse rate (= 60 / period T_period). Ask.

  On the other hand, in step S42, the pulse rate calculation unit 40 obtains the cycle T_period of the second ratio IR (i) in the same manner as in step S22, and subsequently executes step S41 to obtain the second ratio IR thus obtained. The pulse rate (= 60 / period T_period) is obtained by dividing 60 by the period T_period of (i).

  Then, the arithmetic control unit 3 b displays the pulse rate obtained by each of these processes on the pulse rate display unit 51 of the display unit 5.

  In the above-described processing, the integration range for obtaining the expected value ev and the integration range for obtaining the noise component ratio pv may be the same or different.

The blood oxygen saturation calculation unit 39 of the calculation control unit 3b calculates the venous blood oxygen saturation SvO ₂ based on the noise component ratio pv, and calculates the signal component ratio pa based on the noise component ratio pv. Based on the obtained signal component ratio pa, the oxygen saturation SpO ₂ of arterial blood is obtained. Then, the arithmetic control unit 3 b displays the obtained oxygen saturation SvO ₂ and SpO ₂ on the blood oxygen saturation display unit 52 of the display unit 5.

  Further, the reliability calculation unit 41 of the calculation control unit 3 b obtains a predetermined reliability, and the calculation control unit 3 b displays the obtained reliability on the reliability display unit 53 of the display unit 5.

  As described above, in the biological information measuring device Sb of the present embodiment, the first histogram f (p) of the third ratio p based on the measurement data R and IR is obtained, and an expected value as a statistical parameter of the first histogram f (p). ev is obtained, and predetermined biological information is obtained based on measurement data in a predetermined range based on the expected value ev. As described above, the biological information measuring device Sb according to the present embodiment can obtain biological information through simpler processing, and as a result, can reduce power consumption.

  In this embodiment, the expected value ev and the moving average g2 (p) in the first histogram f (p) of the third ratio p are obtained as predetermined statistical parameters, and the expectation of p based on the first histogram f (p) A biological information measuring device Sb is provided that calculates the pulse rate of the living body based on the value ev and the moving average g2 (p), and further calculates the blood oxygen saturation.

  In the second embodiment described above, the statistical parameter calculation unit 37b obtains the expected value ev in the first histogram f (p) of the third ratio p and its moving average g2 (p) as the predetermined statistical parameter, When the third ratio p is larger than the expected value ev or when g2 (p) −f (p) is larger than 0, the pv calculation unit 38b {g2 (p) −f (p)} / ∫ { g2 (p) −f (p)} dp is obtained as the second histogram h2 (p), the noise component ratio pv is obtained based on the second histogram h2 (p), and the pulse rate calculating unit 40 Although the pulse rate of the living body is obtained based on the component ratio pv, the statistical parameter calculation unit 37b obtains the moving average g2 (p) in the first histogram f (p) of the third ratio p, and the moving average g2 (p ) Give a peak The ratio p_p is obtained as the predetermined statistical parameter, and the pv calculation unit 38b determines that the third ratio p is larger than the third ratio p_p that gives the peak of the moving average g2 (p), or g2 (p) −f ( {g2 (p) −f (p)} / ∫ {g2 (p) −f (p)} dp when p) is larger than 0 is obtained as the second histogram h2 (p), and this second histogram h2 Based on (p), the noise component ratio pv may be obtained, and the pulse rate calculator 40 may obtain the pulse rate of the living body based on the noise component ratio pv.

  Even with such a configuration, the biological information measuring device S can obtain biological information through simpler processing, and as a result, power consumption can be reduced. In this configuration, the moving average g2 (p) in the first histogram f (p) of the third ratio p and the third ratio p_p that gives the peak of the moving average g2 (p) are obtained as predetermined statistical parameters. A biological information measuring device Sb is provided that calculates the pulse rate of the living body based on the moving average g2 (p) of the first histogram f (p) and further calculates the blood oxygen saturation.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

Sa, Sb Biological information measuring device 1 Sensor unit 3a, 3b Operation control unit 5 Display unit 11 First sensor unit 12 Second sensor unit 35 Histogram calculation unit 36 Ratio calculation unit 37a, 37b Statistical parameter calculation unit 38a, 38b pv calculation unit 39 Blood oxygen saturation calculator 40 Pulse rate calculator

Claims (7)

A measurement unit that measures a predetermined physiological phenomenon in the living body to be measured and outputs measurement data; and
A histogram calculation unit for obtaining a first histogram based on the measurement data measured by the measurement unit;
A statistical parameter calculator for obtaining a predetermined statistical parameter in the first histogram obtained by the histogram calculator;
A second histogram is obtained based on the first histogram obtained by the histogram calculation unit and the predetermined statistical parameter calculated by the statistical parameter calculation unit, and the predetermined biological information is obtained based on the second histogram. A biological information measuring device comprising: a biological information calculating unit. The measurement unit irradiates the living tissue of the living body with first light having a predetermined first wavelength, receives the first light transmitted or reflected through the living tissue of the living body, and outputs first measurement data. Second measurement data is received by irradiating the biological tissue of the living body with second light having a predetermined second wavelength different from the first wavelength, and receiving or transmitting the second light transmitted or reflected through the biological tissue of the biological body. A sensor unit including a second sensor unit that outputs
The histogram calculation unit calculates a histogram f (p) of a third ratio p between a first ratio of the AC component to the DC component in the first measurement data and a second ratio of the AC component to the DC component in the second measurement data. Obtained as the first histogram,
The statistical parameter calculation unit obtains an expected value ev in the first histogram f (p) as the predetermined statistical parameter,
When the third ratio p is larger than the expected value ev when g1 (p) = f (2 × ev−p), or the g1 (p) −f ( {g1 (p) −f (p)} / ∫ {g1 (p) −f (p)} dp when p) is larger than 0 is obtained as the second histogram, and the living body is calculated based on the second histogram. The biological information measuring device according to claim 1, wherein the pulse rate is calculated. The measurement unit irradiates the living tissue of the living body with first light having a predetermined first wavelength, receives the first light transmitted or reflected through the living tissue of the living body, and outputs first measurement data. Second measurement data is received by irradiating the biological tissue of the living body with second light having a predetermined second wavelength different from the first wavelength, and receiving or transmitting the second light transmitted or reflected through the biological tissue of the biological body. A sensor unit including a second sensor unit that outputs
The histogram calculation unit calculates a histogram f (p) of a third ratio p between a first ratio of the AC component to the DC component in the first measurement data and a second ratio of the AC component to the DC component in the second measurement data. Obtained as the first histogram,
The statistical parameter calculation unit obtains an expected value ev and a moving average g2 (p) in the first histogram f (p) as the predetermined statistical parameter,
The biometric information calculation unit {g2 (p) −f (p) when the third ratio p is larger than the expected value ev or when the g2 (p) −f (p) is larger than 0. } / 情報 {g2 (p) −f (p)} dp is obtained as the second histogram, and the pulse rate of the living body is obtained based on the second histogram. measuring device. The measurement unit irradiates the living tissue of the living body with first light having a predetermined first wavelength, receives the first light transmitted or reflected through the living tissue of the living body, and outputs first measurement data. Second measurement data is received by irradiating the biological tissue of the living body with second light having a predetermined second wavelength different from the first wavelength, and receiving or transmitting the second light transmitted or reflected through the biological tissue of the biological body. A sensor unit including a second sensor unit that outputs
The histogram calculation unit calculates a histogram f (p) of a third ratio p between a first ratio of the AC component to the DC component in the first measurement data and a second ratio of the AC component to the DC component in the second measurement data. Obtained as the first histogram,
The statistical parameter calculation unit obtains a moving average g2 (p) in the first histogram f (p), obtains a third ratio p_p that gives a peak of the moving average g2 (p) as the predetermined statistical parameter,
When the third ratio p is larger than a third ratio p_p that gives the peak of the moving average g2 (p), or when the g2 (p) −f (p) is larger than 0 {G2 (p) −f (p)} / ∫ {g2 (p) −f (p)} dp is obtained as the second histogram, and the pulse rate of the living body is obtained based on the second histogram. The living body information measuring device according to claim 1 characterized by things. The said biological information calculation part changes the calculation formula which calculates | requires the pulse rate of the said biological body according to the value of the standard deviation of the said 1st histogram, The any one of Claim 2 thru | or 4 characterized by the above-mentioned. Biological information measuring device. The biological information measuring apparatus according to any one of claims 2 to 5, wherein the biological information calculation unit further calculates blood oxygen saturation as the predetermined biological information. A measurement process for measuring a predetermined physiological phenomenon in the measurement target and outputting measurement data;
A histogram calculation step for obtaining a first histogram based on the measurement data measured by the measurement step;
A statistical parameter calculating step for obtaining a predetermined statistical parameter in the first histogram obtained by the histogram calculating step;
A second histogram is obtained based on the first histogram obtained by the histogram calculating step and the predetermined statistical parameter calculated by the statistical parameter calculating step, and the predetermined biological information is obtained based on the second histogram. A biological information measuring method comprising: a biological information calculating step.

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