JP2018134470A - Measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: 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 irradiated on an object and measures information such as biological information.

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

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

JP 2003-102694 A JP 2002-51996 A

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

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

  In order to solve the above-described problems, a measuring device according to the present invention emits light to a living body, and a first light receiving section and a second light receiving section that respectively receive return light from the living body of the irradiated light. And 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 Output means for outputting information relating to.

  The effect | action and other gain of this invention are clarified from the form for implementing demonstrated below.

It is a schematic block diagram which shows the outline | summary of the measuring device which concerns on an Example. It is a block diagram which shows the principal part of the calculation apparatus which concerns on an Example. It is a conceptual diagram which shows the concept of a body movement. It is an example of a pulse measurement result. It is an example of the correlation between two output signals. It is a flowchart which shows the measurement process which concerns on an Example. It is a schematic block diagram which shows the outline | summary of the measuring device which concerns on the modification of an Example. It is a top view which shows an example of arrangement | positioning of a light emitting element and a light receiving element. It is a top view which shows an example of arrangement | positioning in case two or more light emitting elements are provided. It is a top view which shows an example of arrangement | positioning in case three or more light receiving elements are provided. It is a schematic block diagram which shows the outline | summary of the pulse oximeter which concerns on an Example.

  Embodiments according to the measurement apparatus, pulse oximeter, measurement method, and computer program of the present invention will be described.

(Measurement device)
The measurement device according to the embodiment includes a light emitting unit that irradiates light to a living body, a first light receiving unit and a second light receiving unit that receive return light from the living body of the irradiated light, 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 that 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 light may be appropriately set according to the measurement target.

  For example, each of a first light receiving unit and a second light receiving unit, which are light receiving elements such as PD (Photodiode), receives the return light from the living body of light irradiated on the living body. Here, the “return light” is a concept including not only light scattered or reflected by the 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 means including a memory, a processor, etc., based on the output signal of the first light receiving unit and the output signal of the second light receiving unit, at least of the output signal of the first light receiving unit and the output signal of the second light receiving unit. Information on noise of one output signal is output.

  Here, according to the inventor's research, the following matters have been found. That is, if the living body is measured symmetrically, noise may be mixed into a measurement signal such as a volume pulse wave signal due to body movement of the living body. Various methods for removing noise caused by body movement have been proposed. On the other hand, when processing for removing noise caused by body movement (hereinafter referred to as “noise removal processing” as appropriate) is performed, there is a possibility that the apparatus performance such as measurement accuracy, responsiveness, stability, etc. may deteriorate. 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 responsiveness decreases. On the other hand, if the acquisition period of the measurement signal used for frequency analysis is shortened, noise is not sufficiently removed and measurement accuracy is lowered.

  However, it is extremely difficult to perform measurement without performing noise removal processing in an environment where body movement occurs. Therefore, if the noise removal process is performed only when the noise to be removed is mixed in the measurement signal, it is expected that the degradation of the apparatus performance is suppressed.

  In the present embodiment, as described above, the output unit outputs 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. Information about noise of one output signal is output. For this reason, 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 (that is, the measurement signal). As a result, according to the measurement device according to the embodiment, it is possible to detect noise (noise) to be removed from the measurement signal related to the object (living body).

  In one aspect of the measurement apparatus according to the embodiment, the output unit obtains information on noise of at least one output signal based on the 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 level of the mixed noise (specifically, for example, It has been found from the study of the present inventor that the larger the noise that is mixed, the lower the correlation.

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

  In another aspect of the measuring apparatus according to the embodiment, it is determined whether at least one of the output signals includes noise based on the information on the output noise, and at least one of the output signals includes noise. If it is, the noise reduction means which reduces the noise contained in at least one output signal is further provided.

  According to this aspect, noise included in the output signal can be reduced, which is very advantageous in practice. It should be noted that various known modes can be applied to the method for reducing noise, and therefore the details thereof are omitted.

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

  According to this aspect, for example, information related to body movement such as the direction of body movement is also output, which is very advantageous in practice.

  In another aspect of the measuring apparatus 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, the noise to be removed from the output signal related to the living body can be suitably detected, which is very advantageous in practice.

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

  The “first light receiving unit and the second light receiving unit that 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” are the first return light and It means a first light receiving part that receives each of the second return light and a second light receiving part 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 with each other (that is, the first light and the second light are alternately irradiated on the living body). For this reason, each of the first light receiving unit and the second light receiving unit alternately receives the first return light and the second return light.

  For example, the output means including a memory, a processor, and the like includes a first output signal of the first light receiving unit that receives one return light 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 related to the living body, similarly to the measurement device according to the embodiment described above.

  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, the noise to be removed from the output signal related to the living body can be suitably detected, which is very advantageous in practice.

(Measurement method)
The measurement method according to the embodiment is a measurement in a measurement apparatus 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 receive return light from the living body of the irradiated light, respectively. Is the method. The measurement method is based on the output signal of the first light receiving unit and the output signal of the second light receiving unit, and 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.

  According to the measurement method according to the embodiment, noise (noise) to be removed from the output signal related to the living body can be detected, similarly to the measurement device according to the above-described embodiment.

(Computer program)
A computer program according to an embodiment is mounted on a measurement 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 receive return light from the living body of the irradiated light, respectively. The information regarding the noise of the output signal 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. To function as output means for outputting.

  According to the computer program of this embodiment, from a recording medium such as a RAM (Random Access Memory), a CD-ROM (Compact Disc Read Only Memory), and a DVD-ROM (DVD Read Only Memory) that stores the computer program. If the computer program is read and executed by a computer provided in the measurement device, or if the computer program is executed after being downloaded via the communication means, the measurement device according to the above-described embodiment is compared. Can be realized easily. Thereby, the noise (noise) which should be removed from the output signal which concerns on a biological body is detectable like the measuring device which concerns on embodiment mentioned above.

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

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

  In FIG. 1, a measuring device 1 processes light emitting means 11 such as a red LED and infrared LED, light receiving means 12 and 13 such as PD, and signals output from the light receiving means 12 and 13, respectively. 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 a blood vessel of a human finger (corresponding to a “living body” according to the present invention). Each of the light receiving means 12 and 13 mainly receives light transmitted through the blood vessel (corresponding to “return light” according to the present invention) and outputs a signal corresponding to the amount of light received.

  For example, as shown in FIG. 1, when measurement is performed by irradiating a blood vessel of a fingertip, the positional relationship between the light emitting means 11 and the light receiving means 12 and 13 varies as the finger moves (see FIG. 3). Then, noise may be mixed in the output signals output from the light receiving units 12 and 13 due to finger movement (ie, body movement).

  Here, simply, for example, a pulse wave, a pulse, a heartbeat or the like is detected from the output signal output from the light receiving means 12 or 13. However, if noise due to body movement 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 (see FIG. 4B). Normal measurement (see broken line) ”).

  On the other hand, various noise removal methods have been proposed to remove noise caused by body movement. By applying a noise removal process to the output signal output from the light receiving means 12 or 13, for example, a pulse wave, a pulse, a heartbeat or the like in which the influence of noise caused by body movement is suppressed is detected. However, when the noise removal process is performed (see FIG. 4 “Noise removed (solid line)”), the response delay is compared to the case where the noise removal process is not performed (see “Normal measurement (dashed line)” in FIG. 4). 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 movement. Therefore, in this embodiment, it is determined whether noise is mixed in the output signals from the light receiving means 12 and 13, and when it is determined that noise is mixed, the noise removal processing is performed. The measurement apparatus 1 is configured.

  Specifically, as illustrated 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 comparators 121, 122, and 123 that compare with a predetermined threshold, 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 means 12 and the output signal from the light receiving means 13 have a high correlation (that is, phase relationship). (The number is high). On the other hand, as shown in FIG. 5B, when there is a body motion, the correlation between the output signal from the light receiving means 12 and the output signal from the light receiving means 13 is low (that is, the correlation coefficient is low).

  The signal component caused by pulsation in the output signal from the light receiving element 12 and the signal component caused by pulsation in the output signal from the light receiving element 13 are in phase over a wide range. On the other hand, the phase of the signal component resulting from body movement changes locally. For this reason, if the output signals from each of 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 means 12 and the output signal from the light receiving means 13 is calculated, it is possible to relatively easily determine whether or not body movement has occurred, and further, the degree of body movement. Can be detected.

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

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

  Similarly, the comparator 123 compares the calculated correlation coefficient with a threshold value 3 different from the threshold value 1 and the threshold value 2. The comparator 123 outputs “1”, for example, when the calculated correlation coefficient is larger than the threshold 3, and outputs “0”, for example, when the calculated correlation coefficient is equal to or smaller than the threshold 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 based on the obtained relationship, the measurement error The correlation coefficient corresponding to the upper limit value of the allowable range, the correlation coefficient corresponding to the maximum value of noise that can be removed by the noise removal process, and the like may be set.

More specifically, the “threshold value 1” according to the present embodiment is set as a correlation coefficient corresponding to noise whose 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 a correlation coefficient corresponding to. The “threshold 3” according to the present embodiment is set as a correlation coefficient corresponding to the minimum value of noise whose measurement error exceeds the allowable range even when the noise removal process is performed. In other words, in this embodiment, “threshold 1> threshold 2> threshold 3” is set.

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

  When “0” is output from the comparator 121 and “1” is output from the comparator 122 (that is, when “threshold 1 ≧ correlation coefficient> threshold 2”), the noise level determination unit 130 “Body motion 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 2 ≧ correlation coefficient> threshold 3”), the noise level determination unit 130 “Body motion removal 2” for which noise removal processing is performed is selected.

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

  With this configuration, when there is no body movement, it is possible to perform a highly responsive measurement in which noise removal processing is not performed, and when body movement occurs, the target is determined according to the degree of body movement. Noise removal processing is performed so as to obtain the measurement accuracy to be performed. Therefore, according to the measuring apparatus 1 according to the present embodiment, it is possible to suppress the measurement responsiveness and the load on the measuring apparatus 1 while appropriately removing noise caused by body movement.

(Measurement process)
A measurement process executed in the measurement apparatus 1 configured as described above will be described with reference to a flowchart of FIG.

  In FIG. 6, first, the correlation coefficient calculation unit 110 of the calculation apparatus 100 acquires an output signal from the light receiving means 12 (step S <b> 101). In parallel with or in parallel with the processing of step S101, the correlation coefficient calculation unit 110 acquires an output signal from the light receiving means 13 (step S102).

  Next, the correlation coefficient calculation unit 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 or not the calculated correlation coefficient is greater than the threshold value 1 (step S104).

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

  When it is determined that the calculated correlation coefficient is equal to or less than the threshold value 1 (step S104: No), the noise level determination unit 130 determines whether the calculated correlation coefficient is greater than the threshold value 2 (step S104). S106). When it is determined that the calculated correlation coefficient is greater 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 means 12 or 13 that has been subjected to simple noise removal processing.

  When it is determined that the calculated correlation coefficient is equal to or less than the threshold value 2 (step S106: No), the noise level determination unit 130 determines whether the calculated correlation coefficient is greater than the threshold value 3 (step S106). S108). When it is determined that the calculated correlation coefficient is greater than the threshold value 3 (step S108: Yes), the noise level determination unit 130 selects 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 means 12 or 13 that has been subjected to the noise removal processing.

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

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

(Modification of measuring device)
Next, a modified example of the measuring apparatus 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 means 1 and 2 mainly receives reflected light (corresponding to “return light” according to the present invention) scattered and reflected by blood vessels (hemoglobin in blood) and outputs a signal corresponding to the amount of light received. .

  In both the so-called transmission type measurement device (see FIG. 1) and the so-called reflection type measurement device (see FIG. 7), the light emitting element and the two light receiving elements can take various positional relationships. Specifically, for example, the light emitting element and the light receiving element are formed so that an isosceles triangle having the same distance between the light emitting element and the light receiving element 1 and the distance between the light emitting element and the light receiving element 2 is formed in a plan view. 1 and the light receiving element 2 may be arranged, respectively (see FIG. 8A). Alternatively, a light emitting element may be arranged in the middle of a 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 so that the distance between the light emitting element and the light receiving element 1 and the distance between the light emitting element and the light receiving element 2 are different from each other (FIG. 8 ( c)).

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

  In this case, a plurality of light emitting elements may be arranged in one place (see FIG. 9A). If comprised in this way, a comparatively high light quantity can be obtained, for example using a light emitting element with a comparatively low light quantity. For this reason, for example, the manufacturing cost can be suppressed and the deterioration of the light emitting element can be suppressed.

  Alternatively, a plurality of sets of light emitting elements and light receiving elements may be arranged (see FIG. 9B). With this configuration, since the distance between the light emitting element and the light receiving element can be reduced, the amount of received light can be increased, which is very advantageous in practice.

  The measurement apparatus 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 arranged on a perpendicular bisector of the line connecting the light receiving element 1 and the light receiving element 2, respectively. According to this configuration, from the fluctuation 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 2 (that is, “(light receiving amount of the light receiving element 1 + light receiving amount of the light receiving element 2) / 2”). , Body motion in the x direction in FIG. 10 can be detected. Further, 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, “{(the light receiving amount of the light receiving element 1 + the light receiving amount of the light receiving element 2). ) / 2 + the amount of light received by the light receiving element 3/2/2)), the body movement in the y direction in FIG. 10 can be detected.

  Alternatively, as shown in FIG. 10B, a light receiving element may be arranged at each vertex of a rectangle centering on the light emitting element. With this configuration, (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) fluctuation in 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 (that is, “(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. Further, (i) the fluctuation of 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 3 (that is, “(the amount of light received by the light receiving element 1 + the amount of light received by the light receiving element 3) / 2”), ii) From the fluctuation 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 (that is, “(the amount of light received by the light receiving element 2 + the amount of light received by the light receiving element 4) / 2”), It is possible to detect body movement in the y direction.

<Pulse oximeter>
Next, the pulse oximeter according to the embodiment will be described with reference to FIG. FIG. 11: is a schematic block diagram which shows the outline | summary of the pulse oximeter based on an Example.

  In FIG. 11A, a 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 calculation device 100 (see FIG. 1, here) (Not shown).

  The calculation device 100 calculates a correlation coefficient between the output signal from the light receiving element 1 and the 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, and the calculation is performed. The correlation coefficient thus obtained is compared with a predetermined threshold (in the above-described embodiment, “threshold 1”, “threshold 2”, and “threshold 3”), and noise caused by body movement is mixed in the output signal. It is determined whether or not. And when it determines with the noise resulting from a body movement mixing in an output signal, a predetermined noise removal process is implemented.

  The pulse oximeter includes an output signal from one of the light receiving element 1 and the light receiving element 2 during a period in which light is emitted from the light emitting means 1 and a signal from the one in a period in which light is emitted from the light emitting means 2. For example, a pulse or the like is detected based on the output signal. In addition, since various well-known aspects are applicable to the function as a pulse oximeter, the description about the detail is omitted.

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

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. Moreover, it is included in the technical scope of the present invention.

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

Claims (1)

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