JP2019213992A - Measuring device - Google Patents

Abstract

To detect noise which has to be removed from a measurement signal relating to an object.SOLUTION: A measuring device (1) comprises: a light emission part (11) which emits light to a living body; a first light-receiving part and a second light-receiving part (12, 13) which respectively receive the return light of the emitted light returned from the living body; and output means (100) which on the basis of an output signal from the first receiving part and that from the second light-receiving part, outputs information about noise of at least one of the output signal from the first light-receiving part and that from the second light-receiving part. The measuring device is capable of easily detecting whether a measurement signal related to a living body includes noise which has to be removed.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a technical field of a measurement device that receives, for example, return light of light applied to an object and measures information such as biological information.

  As this type of device, for example, a pulse wave signal is detected from the transmittance or reflectance of light of a part of the body of the subject, an acceleration signal accompanying body movement is detected, and the pulse wave signal is detected from the detected pulse wave signal. There has been proposed a device that removes a detected acceleration signal and measures a heart rate in which the influence of noise due to body movement is suppressed (see Patent Document 1).

  Alternatively, a vein pulse wave sensor having a vein light emitting portion that emits light having a wavelength of 600 nm (nanometers) to 750 nm, a vein light receiving portion having strong light receiving characteristics for a wavelength of 600 nm to 750 nm, and a vein pulse wave sensor having a wavelength of 800 nm to 1000 nm. An apparatus has been proposed that includes an arterial light emitting unit that emits light of a wavelength and an arterial pulse wave sensor that includes an arterial light receiving unit that has strong light receiving characteristics for a wavelength of 800 nm to 1000 nm. Here, in particular, a technique for measuring a pulse rate from which the influence of body movement has been removed by subtracting a venous signal detected by a venous pulse wave sensor from an arterial signal detected by an arterial pulse wave sensor is proposed. (See Patent Document 2).

JP 2003-102694 A JP-A-2002-51996

  According to the background art described above, processing for suppressing the influence of body movement (ie, noise) is always performed. For this reason, the above-mentioned background art has a technical problem such as a decrease in measurement responsiveness.

  The present invention has been made in view of, for example, the above-described problems, and has as its object to provide a measurement device that can detect noise to be removed from a measurement signal of an object.

  In order to solve the above-mentioned problems, a measuring device of the present invention includes a light emitting unit that irradiates light to a living body, a first light receiving unit that receives return light of the irradiated light from the living body, and a second light receiving unit. And a noise of at least one of an output signal of the first light receiving unit and an output signal of the second light receiving unit based on an output signal of the first light receiving unit and an output signal of the second light receiving unit. Output means for outputting information about

  The operation and other advantages of the present invention will become more apparent from the embodiments explained below.

It is a schematic structure figure showing the outline of the measuring device concerning an example. FIG. 2 is a block diagram illustrating a main part of a calculation device according to an embodiment. It is a conceptual diagram which shows the concept of a body motion. It is an example of a pulse measurement result. It is an example of the correlation between two output signals. 6 is a flowchart illustrating a measurement process according to the embodiment. It is a schematic structure figure showing the outline of the measuring device concerning the modification of an example. It is a top view showing an example of arrangement of a light emitting element and a light sensing element. It is a top view showing an example of arrangement at the time of having two or more light emitting elements. It is a top view which shows an example of arrangement at the time of having three or more light receiving elements. It is a schematic structure figure showing the outline of the pulse oximeter concerning an example.

  An embodiment according to each of the measuring device, the pulse oximeter, the measuring method, and the computer program of the present invention will be described.

(Measurement device)
The measuring device according to the embodiment includes a light emitting unit that irradiates light to the living body, a first light receiving unit and a second light receiving unit that respectively receive return light of the irradiated light from the living body, and a first light receiving unit. Output means for outputting information on noise of at least one of the output signal of the first light receiving unit and the output signal of the second light receiving unit based on the output signal and the output signal of the second light receiving unit.

  For example, a light emitting unit which is a light emitting element such as an LED (Light Emitting Diode) irradiates a living body such as a human body with light. Here, the wavelength of the light may be appropriately set according to the measurement object.

  For example, each of a first light receiving unit and a second light receiving unit, which are light receiving elements such as PDs (Photodiodes), receives return light from the living body of light applied to the living body. Here, “return light” is a concept including not only light scattered or reflected by a living body but also light transmitted through the living body. That is, the measurement device according to the embodiment may be a reflection-type measurement device or a transmission-type measurement device.

  For example, the output unit including a memory, a processor, and the like, based on the output signal of the first light receiving unit and the output signal of the second light receiving unit, outputs at least the output signal of the first light receiving unit and the output signal of the second light receiving unit. The information about the noise of one output signal is output.

  Here, according to the research of the present inventor, the following matters have been found. That is, when the living body is set to be symmetrical for measurement, noise may be mixed into a measurement signal such as a volume pulse signal due to body movement of the living body. Various methods for removing noise caused by body motion have been proposed. On the other hand, when processing for removing noise due to body movement (hereinafter, appropriately referred to as “noise removal processing”) is performed, there is a possibility that device performance such as measurement accuracy, responsiveness, and stability may be reduced. is there.

  Specifically, for example, when frequency analysis of a measurement signal is performed as noise removal processing, it is necessary to acquire a measurement signal for a certain period used for the frequency analysis, and the responsiveness is reduced. On the other hand, if the acquisition period of the measurement signal used for the frequency analysis is shortened, the noise is not sufficiently removed and the measurement accuracy is reduced.

  However, it is extremely difficult to perform measurement without performing any noise removal processing in an environment where body motion occurs. Therefore, if the noise removal processing is performed only when the noise to be removed is mixed in the measurement signal, it is expected that the device performance is suppressed from deteriorating.

  In this embodiment, as described above, at least the output signal of the first light receiving unit and the output signal of the second light receiving unit are output by the output unit based on the output signal of the first light receiving unit and the output signal of the second light receiving unit. Information about the noise of one output signal is output. Therefore, by referring to the information regarding the output noise, it can be relatively easily determined whether the noise to be removed is mixed in the output signal (that is, the measurement signal). As a result, according to the measurement device according to the embodiment, noise (noise) to be removed can be detected from the measurement signal of the object (living body).

  In one aspect of the measuring device according to the embodiment, the output unit outputs information regarding noise of at least one output signal based on a correlation between the output signal of the first light receiving unit and the output signal of the second light receiving unit. Output.

  When noise is mixed in the measurement signal, the correlation between the output signal of the first light receiving unit and the output signal of the second light receiving unit changes depending on the degree of the mixed noise (specifically, for example, It has been found from the study of the inventor of the present invention that the larger the noise mixed, the lower the correlation.)

  Therefore, by referring to the information regarding the output noise, it can be relatively easily determined whether or not the noise to be removed is mixed in the output signal.

  In another aspect of the measurement device according to the embodiment, based on information about the output noise, it is determined whether or not at least one output signal includes noise, and at least one output signal includes noise. And a noise reduction unit that reduces noise included in at least one of the output signals.

  According to this aspect, noise included in the output signal can be reduced, which is extremely advantageous in practice. Various known modes can be applied to the method of reducing noise, and a detailed description thereof will be omitted.

  In another aspect of the measurement device according to the embodiment, the information on noise includes information on body movement of a living body.

  According to this aspect, information on the body movement such as the direction of the body movement is also output, which is extremely advantageous in practice.

  In another aspect of the measuring device according to the embodiment, the positional relationship among the light emitting unit, the first light receiving unit, and the second light receiving unit is fixed.

  According to this aspect, noise to be removed from the output signal relating to the living body can be suitably detected, which is extremely advantageous in practice.

(Pulse oximeter)
The pulse oximeter according to the embodiment includes a first light emitting unit that irradiates the living body with the first light, a second light emitting unit that irradiates the living body with the second light having a wavelength different from the wavelength of the first light, A first light receiving unit and a second light receiving unit that receive the first return light from the living body of light and the second return light from the living body of the second light, respectively, and one of the first return light and the second return light At least one of the first output signal and the second output signal based on the first output signal of the first light receiving unit receiving the return light and the second output signal of the second light receiving unit receiving the one return light. Output means for outputting information on noise of one of the output signals.

  The “first light receiving unit and the second light receiving unit that respectively receive the first return light from the living body of the first light and the second return light from the living body of the second light” include the first return light and the second return light. This means a first light receiving unit that receives each second return light, and a second light receiving unit that receives each of the first return light and the second return light. That is, both the first light receiving unit and the second light receiving unit receive both the first return light and the second return light.

  The first light emitting unit and the second light emitting unit typically emit light alternately (that is, the first light and the second light are alternately irradiated on the living body). Therefore, each of the first light receiving unit and the second light receiving unit receives the first return light and the second return light alternately.

  For example, an output unit including a memory, a processor, and the like includes a first output signal of a first light receiving unit that receives one of the first return light and the second return light, and a first output signal that receives the one return light. Based on the second output signal of the two light receiving units, information on noise of at least one of the first output signal and the second output signal is output.

  The pulse oximeter according to the embodiment can also detect noise (noise) to be removed from the output signal relating to the living body, similarly to the measurement device according to the above-described embodiment.

  In one aspect of the pulse oximeter according to the embodiment, the positional relationship among the first light emitting unit, the second light emitting unit, the first light receiving unit, and the second light receiving unit is fixed.

  According to this aspect, noise to be removed from the output signal relating to the living body can be suitably detected, which is extremely advantageous in practice.

(Measurement method)
A measuring method according to an embodiment measures a light emitting unit that irradiates light to a living body, and a first light receiving unit and a second light receiving unit that respectively receive return light of the irradiated light from the living body. Is the way. The measurement method includes information on noise of at least one of the output signal of the first light receiving unit and the output signal of the second light receiving unit based on the output signal of the first light receiving unit and the output signal of the second light receiving unit. Is provided.

  According to the measuring method according to the embodiment, similarly to the measuring device according to the above-described embodiment, it is possible to detect noise to be removed from an output signal relating to a living body.

(Computer program)
The computer program according to the embodiment is mounted on a measuring device including a light emitting unit that irradiates light to a living body, and a first light receiving unit and a second light receiving unit that respectively receive return light of the irradiated light from the living body. The computer which has performed the information on the noise of at least one of the output signal of the first light receiving unit and the output signal of the second light receiving unit based on the output signal of the first light receiving unit and the output signal of the second light receiving unit Function as output means for outputting

  According to the computer program of the present embodiment, the recording medium such as a RAM (Random Access Memory), a CD-ROM (Compact Disc Read Only Memory), or a DVD-ROM (DVD Read Only Memory) for storing the computer program is used. If the computer program is read and executed by a computer provided in the measuring device, or if the computer program is executed after being downloaded via a communication unit, the measuring device according to the above-described embodiment is compared. It can be achieved easily. Thereby, similarly to the measurement device according to the above-described embodiment, it is possible to detect noise to be removed from the output signal relating to the living body.

<Measurement device>
An embodiment according to the measuring device of the present invention will be described with reference to the drawings. In the present embodiment, a device for measuring a volume pulse wave by an optical method will be described as an example of a measuring device.

(Configuration of measuring device)
A configuration of the measuring device according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram illustrating an outline of a measurement device according to an embodiment. FIG. 2 is a block diagram illustrating a main part of the calculation device according to the embodiment.

  In FIG. 1, a measuring device 1 processes a light output unit 11 such as a red LED or an infrared LED, a light receiving unit 12 or 13 such as a PD, and a signal output from each of the light receiving units 12 and 13. And a calculation device 100. The light emitting means 11 and the light receiving means 12 and 13 are fixed to a support plate.

  The light emitted from the light emitting means 11 is applied to blood vessels of a human finger (corresponding to the “living body” according to the present invention). Each of the light receiving means 12 and 13 mainly receives transmitted light (corresponding to "return light" according to the present invention) transmitted through the blood vessel, and outputs a signal corresponding to the amount of received light.

  For example, as shown in FIG. 1, when measurement is performed by irradiating light to a blood vessel at the fingertip, the movement of the finger changes the positional relationship between the light emitting unit 11 and the light receiving units 12 and 13 (see FIG. 3). Then, there is a possibility that noise is mixed in the output signals output from the light receiving units 12 and 13 due to the movement of the finger (that is, the body movement).

  Here, simply, for example, a pulse wave, a pulse, a heartbeat, and the like are detected from the output signal output from the light receiving unit 12 or 13. However, if noise due to body motion is mixed in the output signal, it is difficult to correctly detect a pulse wave or the like using the output signal from the light receiving means 12 or 13 as it is (FIG. 4B). Normal measurement (broken line) ”).

  On the other hand, various noise removal methods have been proposed to remove noise caused by body motion. By subjecting the output signal output from the light receiving unit 12 or 13 to noise removal processing, a pulse wave, a pulse, a heartbeat, or the like, in which the influence of noise due to body movement is suppressed, is detected. However, when the noise elimination processing is performed (see FIG. 4 “Noise elimination (solid line)”), the response delay is longer than when the noise elimination processing is not performed (see FIG. 4 “Normal measurement (dashed line)”). Occurs.

  As shown in FIG. 4A, for example, a pulse can be correctly detected without noise removal processing if there is no noise due to body motion. Therefore, in the present embodiment, it is determined whether or not noise is mixed in the output signals from the light receiving units 12 and 13, and if it is determined that the noise is mixed, the noise removal processing is performed. The measuring device 1 is configured.

  Specifically, as shown in FIG. 2, the calculation device 100 includes a correlation coefficient calculation unit 110 that calculates a correlation coefficient between output signals output from the light receiving units 12 and 13, and a calculated correlation coefficient. And a predetermined threshold value, and a noise level determination unit 130 that determines the noise level of the output signal.

  Here, as shown in FIG. 5A, when there is no body movement, the output signal from the light receiving unit 12 and the output signal from the light receiving unit 13 have a high correlation (that is, the phase relationship). (The number is high). On the other hand, as shown in FIG. 5B, when there is body movement, the correlation between the output signal from the light receiving unit 12 and the output signal from the light receiving unit 13 is low (that is, the correlation coefficient is low).

  The signal component of the output signal from the light receiving element 12 due to the pulsation and the signal component of the output signal from the light receiving element 13 due to the pulsation are widely in phase. On the other hand, the phase of the signal component caused by the body movement changes locally. Therefore, if the output signals from the light receiving elements 12 and 13 are compared with each other, the presence or absence of body movement can be determined. That is, if the correlation coefficient between the output signal from the light receiving unit 12 and the output signal from the light receiving unit 13 is calculated, it is possible to relatively easily determine whether or not the body movement has occurred, and furthermore, to determine the degree of the body movement relatively easily. Can be detected.

  In FIG. 2, a comparator 121 compares the correlation coefficient calculated by the correlation coefficient calculation unit 110 with a threshold value 1. The comparator 121 outputs, for example, “1” when the calculated correlation coefficient is larger than the threshold value 1, and outputs, for example, “0” when the calculated correlation coefficient is equal to or smaller than the threshold value 1.

  Similarly, the comparator 122 compares the calculated correlation coefficient with a threshold 2 different from the threshold 1. The comparator 122 outputs, for example, “1” when the calculated correlation coefficient is larger than the threshold value 2, and outputs, for example, “0” when the calculated correlation coefficient is smaller than the threshold value 2.

  Similarly, the comparator 123 compares the calculated correlation coefficient with a threshold 3 different from the thresholds 1 and 2. The comparator 123 outputs, for example, “1” when the calculated correlation coefficient is larger than the threshold value 3, and outputs, for example, “0” when the calculated correlation coefficient is equal to or smaller than the threshold value 3.

  Here, the threshold value 1, the threshold value 2, and the threshold value 3 are determined experimentally, empirically, or by simulation, for example, by obtaining the relationship between the degree of noise and the correlation coefficient, and measuring the measurement error based on the obtained relationship. May be set as the correlation coefficient corresponding to the upper limit of the allowable range, the correlation coefficient corresponding to the maximum value of noise that can be removed by the noise removal processing, and the like.

More specifically, “threshold 1” according to the present embodiment is set as a correlation coefficient corresponding to noise for which a measurement error is within an allowable range without performing noise removal processing.
The “threshold value 2” according to the present embodiment is a maximum value of noise that can make a measurement error within an allowable range by performing a simple noise removal process (for example, a simple algorithm and a short processing time). Is set as the correlation coefficient corresponding to. The “threshold value 3” according to the present embodiment is set as a correlation coefficient corresponding to a minimum value of noise in which a measurement error exceeds an allowable range even when noise removal processing is performed. That is, in the present embodiment, the threshold value is set so that “threshold value 1> threshold value 2> threshold value 3”.

  When “1” is output from the comparator 121 (that is, when “correlation coefficient> threshold value 1”), the noise level determination unit 130 selects “normal measurement” in which noise removal processing is not performed.

  If “0” is output from the comparator 121 and “1” is output from the comparator 122 (that is, if “threshold 1 ≧ correlation coefficient> threshold 2”), the noise level determination unit 130 “Body removal 1” for which simple noise removal processing is performed is selected.

  When “0” is output from the comparator 122 and “1” is output from the comparator 123 (that is, when “threshold value 2 ≧ correlation coefficient> threshold value 3”), the noise level determination unit 130 "Body removal 2" for which noise removal processing is performed is selected.

  When “0” is output from the comparator 123 (that is, when “threshold value 3 ≧ correlation coefficient”), the noise level determination unit 130 stops the measurement for a predetermined period (for example, one cycle period).

  With this configuration, it is possible to perform measurement with good responsiveness in which the noise removal processing is not performed when there is no body movement, and when the body movement occurs, the target is set according to the degree of the body movement. A noise removal process is performed to obtain the required measurement accuracy. Therefore, according to the measuring device 1 according to the present embodiment, the responsiveness of measurement and the load on the measuring device 1 can be suppressed while appropriately removing noise caused by body movement.

(Measurement processing)
The measurement processing executed in the measurement device 1 configured as described above will be described with reference to the flowchart in FIG.

  6, first, the correlation coefficient calculation unit 110 of the calculation device 100 acquires an output signal from the light receiving unit 12 (Step S101). In parallel with or before or after the process of step S101, the correlation coefficient calculation unit 110 acquires an output signal from the light receiving unit 13 (step S102).

  Next, the correlation coefficient calculator 110 calculates a correlation coefficient between the output signal from the light receiving unit 12 and the output signal from the light receiving unit 13 (Step S103). Subsequently, the noise level determination unit 130 determines whether the calculated correlation coefficient is larger than the threshold 1 (step S104).

  When it is determined that the calculated correlation coefficient is larger than the threshold value 1 (Step S104: Yes), the noise level determination unit 130 selects the normal measurement (Step S105). As a result, a value such as a pulse is output based on the output signal from the light receiving unit 12 or 13 to which the noise removal processing has not been performed.

  When it is determined that the calculated correlation coefficient is equal to or smaller than the threshold 1 (Step S104: No), the noise level determination unit 130 determines whether the calculated correlation coefficient is larger than the threshold 2 (Step S104). S106). When it is determined that the calculated correlation coefficient is larger than the threshold value 2 (step S106: Yes), the noise level determination unit 130 selects body motion removal 1 (step S107). As a result, a value such as a pulse is output based on the output signal from the light receiving unit 12 or 13 to which the simple noise removal processing has been performed.

  When it is determined that the calculated correlation coefficient is equal to or smaller than the threshold 2 (Step S106: No), the noise level determination unit 130 determines whether the calculated correlation coefficient is larger than the threshold 3 (Step S106). S108). When it is determined that the calculated correlation coefficient is larger than the threshold value 3 (Step S108: Yes), the noise level determination unit 130 selects the body motion removal 2 (Step S109). As a result, a value such as a pulse is output based on the output signal from the light receiving unit 12 or 13 on which the noise removal processing has been performed.

  When it is determined that the calculated correlation coefficient is equal to or smaller than the threshold value 3 (step S108: No), the noise level determination unit 130 temporarily stops the measurement (step S110). At this time, it may be configured that the user is notified that measurement is impossible.

  The “calculating device 100” according to the embodiment is an example of the “output unit” and the “noise reducing unit” according to the present invention.

(Modification of measuring device)
Next, a modified example of the measuring device according to the embodiment will be described with reference to FIGS.

  As shown in FIG. 7, the measuring device may be configured to include a light emitting element, a light receiving element 1 and a light receiving element 2 fixed on the same support plate. In this case, the light emitted from the light emitting means is applied to a blood vessel of a human finger. Each of the light receiving units 1 and 2 mainly receives reflected light (corresponding to “return light” according to the present invention) scattered and reflected by a blood vessel (hemoglobin in blood), and outputs a signal corresponding to the amount of received light. .

  In both the so-called transmission-type measuring device (see FIG. 1) and the so-called reflection-type measuring device (see FIG. 7), the light-emitting element and the two light-receiving elements can have various positional relationships. Specifically, for example, the light-emitting element and the light-receiving element are formed such that an isosceles triangle in which the distance between the light-emitting element and the light-receiving element 1 is equal to the distance between the light-emitting element and the light-receiving element 2 in a plan view. 1 and the light receiving element 2 may be arranged respectively (see FIG. 8A). Alternatively, the light emitting element may be arranged in the middle of the straight line connecting the light receiving element 1 and the light receiving element 2 (see FIG. 8B). Alternatively, the light emitting element, the light receiving element 1 and the light receiving element 2 may be arranged such that the distance between the light emitting element and the light receiving element 1 is different from the distance between the light emitting element and the light receiving element 2 (FIG. c)).

  The measuring device according to the embodiment may further include a plurality of light emitting elements (see FIG. 9). Note that the wavelength of light emitted from each of the plurality of light emitting elements is typically the same.

  In this case, a plurality of light emitting elements may be arranged at one place (see FIG. 9A). With this configuration, for example, a relatively high light amount can be obtained by using a light emitting element having a relatively low light amount. Therefore, for example, it is possible to suppress the manufacturing cost and the deterioration of the light emitting element.

  Alternatively, a plurality of sets of light emitting elements and light receiving elements may be arranged (see FIG. 9B). With such a configuration, the distance between the light emitting element and the light receiving element can be reduced, so that the amount of received light can be increased, which is extremely advantageous in practical use.

  The measuring device according to the embodiment may further include one light emitting element and three or more light receiving elements (see FIG. 10).

  In this case, as shown in FIG. 10A, the light emitting element and the light receiving element 3 may be respectively arranged on a vertical bisector of a line connecting the light receiving element 1 and the light receiving element 2. With this configuration, the average value of the light receiving amount of the light receiving element 1 and the light receiving amount of the light receiving element 2 (ie, “((light receiving amount of light receiving element 1 + light receiving amount of light receiving element 2) / 2))” , The body movement in the x direction in FIG. 10 can be detected. Also, the average value of the light receiving amount of the light receiving element 1 and the light receiving amount of the light receiving element 2 and the average value of the light receiving amount of the light receiving element 3 (that is, “｛(light receiving amount of the light receiving element 1 + light receiving amount of the light receiving element 2) 10), the body movement in the y direction in FIG. 10 can be detected from the fluctuation of the amount of light received by the light receiving element 3) / 2 +).

  Alternatively, as shown in FIG. 10B, a light receiving element may be arranged at each vertex of a rectangle centered on the light emitting element. According to this structure, (i) the average value of the amount of light received by the light receiving element 1 and the amount of light received by the light receiving element 2 (that is, "((the amount of light received by the light receiving element 1 + the amount of light received by the light receiving element 2) / 2)") And (ii) the average value of the amount of light received by the light receiving element 3 and the amount of light received by the light receiving element 4 (ie, “(the amount of light received by the light receiving element 3 + the amount of light received by the light receiving element 4) / 2”). Thus, the body movement in the x direction in FIG. 10 can be detected. Also, (i) the variation of the average value of the light receiving amount of the light receiving element 1 and the light receiving amount of the light receiving element 3 (that is, “((the light receiving amount of the light receiving element 1 + the light receiving amount of the light receiving element 3) / 2))”; ii) From the variation of the average value of the amount of light received by the light receiving element 2 and the amount of light received by the light receiving element 4 (ie, “(the amount of light received by the light receiving element 2 + the amount of light received by the light receiving element 4) / 2”), FIG. The body motion in the y direction can be detected.

<Pulse oximeter>
Next, a pulse oximeter according to an embodiment will be described with reference to FIG. FIG. 11 is a schematic configuration diagram illustrating an outline of the pulse oximeter according to the example.

  In FIG. 11A, the pulse oximeter includes a light emitting element 1 that is, for example, a red LED, a light emitting element 2 that is, for example, an infrared LED, a light receiving element 1 and a light receiving element 2, and a calculating device 100 (see FIG. (Not shown).

  The calculating device 100 calculates a correlation coefficient between an output signal from the light receiving element 1 and an output signal from the light receiving element 2 during a period in which light is emitted from one of the light emitting element 1 and the light emitting element 2. The obtained correlation coefficient is compared with a predetermined threshold value (“threshold value 1”, “threshold value 2”, and “threshold value 3” in the above-described embodiment), and noise resulting from body movement is mixed in the output signal. Is determined. Then, when it is determined that noise due to body movement is mixed in the output signal, predetermined noise removal processing is performed.

  As a pulse oximeter, an output signal from one of the light receiving element 1 and the light receiving element 2 during a period when light is emitted from the light emitting unit 1 and a signal from the one during a period when light is emitted from the light emitting unit 2 For example, a pulse or the like is detected based on the output signal. It should be noted that various known modes can be applied to the function as the pulse oximeter, and a detailed description thereof will be omitted.

  As shown in FIG. 11B, the presence or absence of body movement is detected based on the light emitted from the light emitting element 1 and the output signals from the light receiving elements 1 and 2, and the light emitting element 1 and the light emitting element are detected. For example, a pulse or the like may be detected from the light emitted from each of the light receiving elements 2 and the output signal from the light receiving element 2.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or idea of the invention which can be read from the claims and the entire specification, and a measuring device with such a change is also applicable. Also, they are included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Measuring device, 11 ... Light emitting means, 12, 13 ... Light receiving means, 100 ... Calculation device, 110 ... Correlation coefficient calculation part, 130 ... Noise level determination part

Claims (1)

A light emitting unit that irradiates light to a living body,
A first light receiving unit and a second light receiving unit that respectively receive return light from the living body of the irradiated light,
Based on an output signal of the first light receiving unit and an output signal of the second light receiving unit, information on noise of at least one of the output signal of the first light receiving unit and the output signal of the second light receiving unit is provided. Output means for outputting,
A measuring device comprising: