JP2017136429A - Measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure information on a measurement target by removing unnecessary components such as a body motion.SOLUTION: A measuring instrument comprises: light emission means (201) for irradiating a measurement target (500) with light; first light reception means (211) and second light reception means (212) for receiving return light from the measurement target (500) irradiated with the light; and calculation means (320) for calculating information relating to the measurement target on the basis of the difference between sum signal of light received by the first light reception means and that received by the second light reception means and the difference signal between both of the lights. A measuring instrument like this is capable of accurately measuring information on the measurement target by removing unnecessary components such as a body motion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technical field of a measuring instrument that measures various information such as biological information based on, for example, return light from a measurement target.

  In this type of measuring instrument, for example, light is emitted from a light emitting element to a living body or the like to be measured, and biological information such as pulsation is measured based on return light detected by the light receiving element. One light receiving element may be used in the measuring instrument, but two or more light receiving elements may be used in order to realize more suitable measurement.

  For example, Patent Document 1 proposes a technique of detecting pulsation based on a difference signal between two light receiving elements. Patent Document 2 proposes a technique for detecting body movement based on a difference signal between two light receiving elements. Patent Document 3 proposes a technique for equalizing the distance between a light emitting element and two light receiving elements in order to prevent unnecessary offset components from being superimposed on a tracking signal.

International Publication No. 99/12469 Japanese Patent No. 3789487 Japanese Patent No. 3966434

  When detecting biological information, the detection signal may be disturbed due to the movement of the living body being measured. For this reason, in order to detect biological information correctly, it is preferable that the influence by a body motion can be removed from a detection signal. However, in the body movement detection method described in Patent Document 2 described above, when the light receiving element is arranged at a distant position, the path of light propagating in the living body is different, and as a result, different bodies Motion will be detected. For example, when detecting a pulsation in a living finger or the like, different body movements are detected on the fingertip side and the finger base side. Thus, it can be said that it is difficult to accurately detect body movements in the prior art including the above-mentioned patent document.

  The present invention has been made in view of the above-described problems, for example, and provides a measuring instrument capable of accurately measuring information on a measurement target by removing unnecessary components such as body movements. Is an issue.

  In order to solve the above-described problem, the measuring instrument includes a light emitting unit that emits light, a first light receiving unit and a second light receiving unit that receive return light from the measurement target of the irradiated light, and the first light receiving unit. A difference signal obtained by subtracting a difference signal between the light received by the first light receiving means and the light received by the second light receiving means from the sum signal of the light received by the light receiving means and the light received by the second light receiving means. And calculating means for calculating information related to the measurement target.

  Such an operation and gain of the present invention will be clarified from the embodiments described below.

It is a schematic block diagram which shows the whole structure of the measuring device which concerns on 1st Example. It is a perspective view which shows the measuring method of the biometric information by the measuring device which concerns on 1st Example. It is a top view which shows the distance relationship between the light emitting element of the measuring device which concerns on 1st Example, and a light receiving element. It is a flowchart which shows operation | movement of the measuring device which concerns on 1st Example. It is a graph (the 1) which shows an example of a sum signal. It is a graph (the 1) which shows an example of a difference signal. It is a graph (the 1) which shows an example of a sum signal, a difference signal, and a difference signal. It is a graph (the 2) which shows an example of a sum signal. It is a graph (the 2) which shows an example of a difference signal. It is a graph (the 2) which shows an example of a sum signal, a difference signal, and a difference signal. It is a top view which shows the distance relationship between the light emitting element of the measuring device which concerns on 2nd Example, and a light receiving element. It is a top view which shows the modification of the measuring device which concerns on 2nd Example. It is a flowchart which shows operation | movement of the measuring device which concerns on 2nd Example. It is a top view which shows the distance relationship between the light receiving elements of the measuring device which concerns on 3rd Example. It is a flowchart which shows operation | movement of the measuring device which concerns on 3rd Example.

  Hereinafter, embodiments according to the measuring instrument will be described in order.

  The first measuring instrument of the present embodiment includes a light emitting unit that emits light, a first light receiving unit and a second light receiving unit that receive return light from the measurement target of the irradiated light, and the first light receiving unit. Calculating means for calculating information on the measurement target based on a difference between a sum signal and a difference signal between the light received by the means and the light received by the second light receiving means.

  According to the first measuring instrument of the present embodiment, at the time of operation, light is emitted from a light emitting means including, for example, an LED (Light Emitting Diode) or the like toward a living body or the like to be measured. . The light emitted from the light emitting means is scattered or transmitted by the measurement target, and is detected as return light by the first light receiving means and the second light receiving means, respectively. Each of the first light receiving means and the second light receiving means includes a photodiode and outputs a detection signal corresponding to the detected return light.

  When detection signals are output from the first light receiving means and the second light receiving means, for example, a calculating means including an arithmetic circuit or the like calculates a sum signal and a difference signal of these detection signals. That is, a sum signal obtained by adding the detection signal from the first light receiving means and the detection signal from the second light receiving means, and a difference signal that is a difference between the detection signal from the first light receiving means and the detection signal from the second light receiving means are calculated. Is done.

  Subsequently, the calculation means calculates the difference between the above sum signal and difference signal. Based on the difference between the sum signal and the difference signal, information about the measurement target is calculated. An example of the calculated information is pulsation in a living body.

  Here, in particular, the detection signal obtained from each of the first light receiving means and the second light receiving means is one piece of information related to the measurement target (for example, information that does not change due to a slight difference in position such as a pulsation component of a living body). Are included in the same level, but other information related to the measurement target (for example, information that fluctuates due to a slight difference in position such as a body motion component of a living body) is included in a different state. For this reason, in the difference signal that is the difference between the detection signals, one piece of information about the measurement target is canceled (offset), and only other information about the measurement target remains. Therefore, only the other information can be extracted from a plurality of types of information obtained from the measurement target.

  Further, by subtracting the difference signal from the sum signal of the detection signals, other information included in each of the sum signal and the difference signal is canceled. As a result, only the one information can be extracted from a plurality of types of information obtained from the measurement target.

  As described above, according to the measuring instrument according to the present embodiment, only specific information can be extracted from various types of information included in the detection signal. Specifically, for example, only a pulsation component or only a body motion component can be extracted from a detection signal obtained from a living body to be measured. Therefore, it is possible to remove information unnecessary for measurement and accurately measure information on the measurement target.

  In one aspect of the first measuring instrument of the present embodiment, the distance between the light emitting point of the light emitting means and the first light receiving means is equal to the distance between the light emitting point of the light emitting means and the second light receiving means.

  According to this aspect, since the light receiving condition of the first light receiving unit and the light receiving condition of the second light receiving unit can be brought close to each other, specific information can be extracted more accurately from the detection signal of each light receiving unit. Become.

  In addition, “equal” in this aspect is a broad concept including that the two values are close to the extent that the above-described effect can be sufficiently obtained, in addition to the case where the two values completely match.

  The second measuring instrument of the present embodiment includes a first light receiving means pair and a second light receiving means for irradiating light and two light receiving means for receiving return light from the measurement target of the irradiated light. In each of the light receiving means pair, the first light receiving means pair, and the second light receiving means pair, the output of one light receiving means and the output of the other light receiving means are added to obtain an added output, and the first light receiving means pair In each of the first light-receiving means pair and the second light-receiving means pair, one light-receiving means in which the sum output is added to the sum output of the second light-receiving means pair to generate a sum signal And subtracting the output of the other light receiving means to obtain a subtraction output, and adding the subtraction output of the first light receiving means pair and the subtraction output of the second light receiving means pair to generate a difference signal And the measured pair based on the difference between the sum signal and the difference signal. And a calculating means for calculating information related.

  According to the second measuring instrument of the present embodiment, at the time of operation, light is emitted from a light emitting means including an LED or the like toward a living body or the like to be measured. The light emitted from the light emitting means is scattered or transmitted by the measurement target, and detected as return light by the first light receiving means pair and the second light receiving means pair, respectively. Each of the first light receiving means pair and the second light receiving means pair includes one light receiving means and another light receiving means. Each of the one light receiving unit and the other light receiving unit includes a photodiode and outputs a detection signal corresponding to the detected return light.

  When a detection signal is output from the first light receiving means pair and the second light receiving means pair, the sum signal generating means outputs the output of one light receiving means and the other light receiving in each of the first light receiving means pair and the second light receiving means pair. The outputs of the means are added to obtain an added output. That is, the output of one light receiving means for the first light receiving means and the output of the other light receiving means are added to obtain the added output of the first light receiving means pair, and the output of the one light receiving means for the second light receiving means. And the outputs of the other light receiving means are added to obtain the added output of the second light receiving means pair. Subsequently, the sum signal generating means adds the addition output of the first light receiving means pair and the addition output of the second light receiving means pair to generate a sum signal. That is, the sum signal is a signal obtained by adding the detection signals of the four light receiving means included in the first light receiving means pair and the second light receiving means pair.

  On the other hand, in the difference signal generating means, the output of one light receiving means and the output of the other light receiving means in each of the first light receiving means pair and the second light receiving means pair are subtracted to obtain a subtracted output. That is, the output of one light receiving means for the first light receiving means and the output of the other light receiving means are subtracted to obtain the subtracted output of the first light receiving means pair, and the output of the one light receiving means for the second light receiving means. And the outputs of the other light receiving means are subtracted to obtain the subtracted output of the second light receiving means pair. Subsequently, the difference signal generating means adds the subtraction output of the first light receiving means pair and the subtraction output of the second light receiving means pair to generate a difference signal. That is, the difference signal is a signal obtained by adding the difference signals of the two light receiving means included in the first light receiving means pair and the difference signals of the two light receiving means included in the second light receiving means pair.

  When the sum signal and the difference signal are calculated, the difference between the sum signal and the difference signal is calculated by the calculation means. Based on the difference between the sum signal and the difference signal, information about the measurement target is calculated. An example of the calculated information is pulsation in a living body.

  Here, in particular, the detection signal obtained from each of the one light receiving means and the other light receiving means in the first light receiving means pair and the second light receiving means pair is a piece of information (for example, a pulsating component of a living body). Information that does not change due to slight differences in position), while other information related to the measurement target (for example, information that varies according to slight positional differences such as body movement components of a living body). Includes in different states. For this reason, in the difference signal obtained by adding the subtraction output and the subtraction output, which are the differences between the detection signals, one information regarding the measurement target is canceled (offset), and only other information regarding the measurement target remains. Therefore, only the other information can be extracted from a plurality of types of information obtained from the measurement target.

  Further, by subtracting the difference signal from the sum signal of the detection signals, other information included in each of the sum signal and the difference signal is canceled. As a result, only the one information can be extracted from a plurality of types of information obtained from the measurement target.

  As described above, according to the measuring instrument according to the present embodiment, only specific information can be extracted from various types of information included in the detection signal. Specifically, for example, only a pulsation component or only a body motion component can be extracted from a detection signal obtained from a living body to be measured. Therefore, it is possible to remove information unnecessary for measurement and accurately measure information on the measurement target.

  In one aspect of the second measuring instrument of the present embodiment, the distance between the light emitting point of the light emitting unit and the one light receiving unit of the first light receiving unit pair is the light emitting point of the light emitting unit and the first light receiving unit pair. The distance between the light emitting point of the light emitting means and one light receiving means of the second light receiving means pair is equal to the distance between the light emitting point of the light emitting means and the other light receiving means pair. It is equal to the distance to the light receiving means.

  According to this aspect, the light receiving condition of one light receiving unit in the first light receiving unit pair and the light receiving condition of the other light receiving unit in the first light receiving unit pair can be brought close to each other, and one light reception in the second light receiving unit pair The light receiving conditions of the means and the light receiving conditions of the other light receiving means in the second light receiving means pair can be made closer to each other. For this reason, it becomes possible to extract specific information more accurately from the detection signal of each light receiving means.

  In addition, “equal” in this aspect is a broad concept including that the two values are close to the extent that the above-described effect can be sufficiently obtained, in addition to the case where the two values completely match.

  The third measuring instrument of this embodiment includes a light emitting means for irradiating light, a first light receiving means for receiving return light from the measurement target of the irradiated light, a second light receiving means, a third light receiving means, A first computing means for computing a fourth light receiving means, a first addition output obtained by adding the outputs of the first light receiving means and the second light receiving means adjacent in one direction, and a subtracted first subtraction output; A second calculation means for calculating a second addition output obtained by adding the outputs of the third light receiving means and the fourth light receiving means adjacent to each other along the one direction, and a second subtraction output obtained by subtraction. A third calculation means for calculating a third addition output obtained by adding the outputs of the first light receiving means and the third light receiving means adjacent to each other in a direction different from the direction, and a subtracted third subtraction output; Add the outputs of the second light receiving means and the fourth light receiving means adjacent along the other direction. Fourth operation means for calculating the fourth addition output and the subtracted fourth subtraction output respectively, and adding the first addition output and the second addition output to generate a sum signal for the one direction. 1 sum signal generation means, first difference signal generation means for adding the first subtraction output and the second subtraction output to generate a difference signal for the one direction, the third addition output, and the fourth addition A sum signal is added to generate a sum signal for the other direction, and a second sum signal generating means for adding the third subtraction output and the fourth subtraction output to generate a difference signal for the other direction. Second difference signal generating means, and calculating means for calculating information on the measurement target based on the difference between the sum signal and the difference signal in each of the position direction and the other direction.

  According to the third measuring instrument of the present embodiment, at the time of operation, light is emitted from a light emitting means including an LED or the like toward a living body or the like to be measured. The light emitted from the light emitting means is scattered or transmitted by the measurement target, and is detected as return light by the first light receiving means, the second light receiving means, the third light receiving means, and the fourth light receiving means, respectively. Each of the first to fourth light receiving means is configured to include a photodiode or the like, and outputs a detection signal corresponding to the detected return light.

  When a detection signal is output from the first to fourth light receiving means, a first addition output obtained by adding the outputs of the first light receiving means and the second light receiving means adjacent in one direction in the first calculation means; The subtracted first subtraction output is calculated. In the second calculation means, a second addition output obtained by adding the outputs of the third light receiving means and the fourth light receiving means adjacent in one direction and a subtracted second subtraction output are calculated. In the third calculation means, a third addition output obtained by adding the outputs of the first light receiving means and the third light receiving means adjacent to each other in a direction different from the one direction, and a subtracted third subtraction output are calculated. Is done. In the fourth calculation means, a fourth addition output obtained by adding the outputs of the second light receiving means and the fourth light receiving means adjacent to each other in the other direction and a subtracted fourth subtraction output are calculated.

  The first addition output and the second addition output are added by the first sum signal generating means, and a sum signal for one direction is generated. Further, the first subtraction output and the second subtraction output are added by the first difference signal generation means, and a difference signal for one direction is generated. Similarly, the 3rd addition output and the 4th addition output are added in the 2nd sum signal production | generation means, and the sum signal regarding another direction is produced | generated. Further, the third subtraction output and the fourth subtraction output are added by the second difference signal generating means, and a difference signal for the other direction is generated. That is, a sum signal and a difference signal are generated for each of one direction and the other direction.

  When the sum signal and the difference signal are calculated, the difference between the sum signal and the difference signal in each direction is calculated by the calculation means. Specifically, the difference between the sum signal related to one direction and the difference signal related to one direction is calculated, and the difference between the sum signal related to the other direction and the difference signal related to the other direction is calculated. That is, the difference between the sum signal and the difference signal is generated for each of one direction and the other direction.

  When the difference between the sum signal and the difference signal is calculated, information about the measurement target is calculated based on the calculated difference regarding each direction. For example, information related to the measurement target is calculated based on the difference related to one direction, and similarly information related to the measurement target is calculated based on the difference related to the other direction. Note that one direction is obtained by performing a predetermined calculation (for example, calculation of an average value, etc.) using information calculated based on a difference regarding one direction and information calculated based on a difference regarding another direction. It is also possible to calculate information based on both the difference regarding and the difference regarding other directions. Incidentally, as an example of the information on the living body calculated here, pulsation in the living body can be cited.

  Here, in particular, the detection signal obtained from each of the first to fourth light receiving means has the same information on the measurement target (for example, information that does not change due to a slight difference in position such as a pulsation component of a living body). On the other hand, it includes other information related to the measurement target (for example, information that fluctuates due to a slight difference in position such as a body motion component of a living body) in a different state. For this reason, in the difference signal obtained by adding the differences between the detection signals, one information related to the measurement target is canceled (offset), and only other information related to the measurement target remains. Therefore, only the other information can be extracted from a plurality of types of information obtained from the measurement target.

  Further, by subtracting the difference signal from the sum signal of the detection signals, other information included in each of the sum signal and the difference signal is canceled. As a result, only the one information can be extracted from a plurality of types of information obtained from the measurement target.

  In this embodiment, in particular, since the difference between the sum signal and the difference signal is calculated for each of the one direction and the other direction, it is higher than the case where the difference between the sum signal and the difference signal is calculated only for one direction. Information about a living body can be calculated with high accuracy.

  As described above, according to the measuring instrument according to the present embodiment, only specific information can be extracted from various types of information included in the detection signal. Specifically, for example, only a pulsation component or only a body motion component can be extracted from a detection signal obtained from a living body to be measured. Therefore, it is possible to remove information unnecessary for measurement and accurately measure information on the measurement target.

  In one aspect of the third measuring instrument of the present embodiment, the first light receiving means, the second light receiving means, the third light receiving means, and the fourth light receiving means are equal to each other in the distance adjacent to each other in plan view. It is arranged as follows.

  According to this aspect, the distance between the first light receiving means and the second light receiving means adjacent along one direction, the distance between the third light receiving means and the fourth light receiving means adjacent along the one direction, the other The distance between the first light receiving means and the third light receiving means adjacent to each other in the direction and the distance between the second light receiving means and the fourth light receiving means adjacent to each other in the other direction are arranged to be equal.

  As a result, the first addition output obtained by adding the outputs of the first light receiving means and the second light receiving means adjacent along one direction, the first subtraction output obtained by subtraction, the third light receiving means adjacent along the one direction, and The second addition output obtained by adding the output of the fourth light receiving means, the second subtraction output obtained by subtraction, the third addition output obtained by adding the outputs of the first light receiving means and the third light receiving means adjacent along the other direction, and subtracted. The third subtracted output, the fourth added output obtained by adding the outputs of the second light receiving unit and the fourth light receiving unit adjacent to each other in the other direction, and the subtracted fourth subtracted output are calculated under the same conditions. That is, each added output and subtracted output is calculated as a parameter relating to two light receiving elements arranged at a predetermined interval.

  Therefore, the sum signal and difference signal obtained by adding each of these addition output and subtraction output can be made appropriate. Therefore, it is possible to accurately measure information on the measurement target in each of one direction and the other direction.

  In another aspect of the third measuring instrument of the present embodiment, the distance between the light emitting point of the light emitting means and each of the first light receiving means, the second light receiving means, the third light receiving means, and the fourth light receiving means is: Each is equal.

  According to this aspect, the light receiving conditions of the first to fourth light receiving means can be made closer to each other. For this reason, it becomes possible to extract specific information more accurately from the detection signal of each light receiving means.

  In addition, “equal” in this aspect is a broad concept including that the two values are close to the extent that the above-described effect can be sufficiently obtained, in addition to the case where the two values completely match.

  In another aspect of the measuring instrument of the present embodiment, the calculation means calculates information on the measurement target based on the difference between the frequency component of the sum signal and the frequency component of the difference signal.

  According to this aspect, frequency analysis is performed on the sum signal and the difference signal, and information on the measurement target is calculated using the frequency component that is the analysis result. In this way, since specific information can be detected using the peak of the frequency component, more suitable measurement can be realized.

  In the aspect using the frequency component described above, the calculation unit further includes a normalization unit that normalizes the frequency component of the sum signal and the frequency component of the difference signal by dividing the frequency component by the respective maximum values. Information on the measurement target may be calculated based on a difference frequency component that is a difference between the normalized frequency component of the sum signal and the normalized frequency component of the difference signal.

  In this case, the frequency component of the sum signal is normalized by being divided by the maximum value of the frequency component of the sum signal. Similarly, the frequency component of the difference signal is also divided and normalized by the maximum value of the frequency component of the difference signal. Therefore, the peak of the frequency component can be easily detected, and more suitable measurement can be realized.

  In the aspect using the normalized frequency component described above, the calculation unit may estimate a frequency indicating a maximum amplitude in the difference frequency component as a pulsation cycle of the measurement target.

  In this case, the sum signal includes the pulsation component and the body motion component of the living body to be measured. On the other hand, since the pulsation component is canceled in the difference signal, only the body motion component is included. For this reason, when the difference frequency component which is the difference between the frequency components of the sum signal and the difference signal is calculated, only the body motion component included in both the sum signal and the difference signal is canceled, and only the pulsation component remains. Therefore, the frequency showing the maximum amplitude in the difference frequency component can be estimated as the pulsation cycle of the living body.

  Hereinafter, embodiments of measuring instruments will be described with reference to the drawings.

<1: First embodiment>
First, the measuring instrument according to the first embodiment will be described. In the following, an example in which the measuring instrument is applied to a pulsation measuring device will be described (the same applies to the following embodiments).

<1-1: Configuration of measuring instrument>
First, the configuration of the measuring instrument according to the first embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic configuration diagram showing the overall configuration of the measuring instrument according to the first embodiment. FIG. 2 is a perspective view showing a biological information measuring method by the measuring instrument according to the first embodiment, and FIG. 3 is a plan view showing the distance relationship between the light emitting element and the light receiving element of the measuring instrument according to the first embodiment. FIG.

  In FIG. 1, the measuring instrument 101 according to the present embodiment includes a probe 111, a wiring unit 310, a biological information calculation unit 320, and a display 330.

  The probe 111 is provided with a light emitting element 201 that emits light to a living body to be measured, a first light receiving element 211 and a second light receiving element 212 that receive return light from the living body, and a light shielding plate 250. Yes. The light emitting element 201 is a specific example of “light emitting means” and includes, for example, one or a plurality of LEDs. The first light receiving element 211 and the second light receiving element 212 are specific examples of “first light receiving means” and “second light receiving means”, respectively, and are configured as photodiodes having the same structure. The light shielding plate 250 is provided to prevent light emitted from the light emitting element 201 from going directly to the first light receiving element 211 and the second light receiving element 212 (that is, without being scattered or transmitted in the living body). ing.

  As shown in FIG. 2, the probe 111 according to the present embodiment is attached to a living body 500 (for example, a fingertip or an earlobe) at the time of measurement (in FIG. 2, for convenience of explanation, the living body 500, the probe 111, and the like are attached. However, the living body 500 and the probe 11 are typically attached so as to be in contact with each other). At the time of measurement, of the light emitted from the light emitting element 201, the light reflected by the living body 500 is received by the first light receiving element 211 and the second light receiving element 212.

  In the present embodiment, as described above, the reflection type device that receives the reflected light in the living body 500 has been described. However, the present invention can also be applied to a transmission type device that receives the transmitted light in the living body 500. In the transmission type device, the first light receiving element 211 and the second light receiving element 212 are arranged on the opposite side through the living body 500 when viewed from the light emitting element 201.

  As shown in FIG. 3, in the probe 111 according to this embodiment, the distance relationship between the light emitting element 201 and the first light receiving element 211 and the second light receiving element 212 is clearly defined. Specifically, the distance L1 from the light emitting point of the light emitting element 201 to the light receiving point of the first light receiving element 211 and the distance L2 from the light emitting point of the light emitting element 201 to the light receiving point of the second light receiving element 212 are made equal to each other. ing. Therefore, return light is incident on the first light receiving element 211 and the second light receiving element 212 under the same conditions.

  Returning to FIG. 1, the probe 111 is connected to the biological information calculation unit 320 via the wiring unit 310. The biological information calculation unit 320 is connected to the display 330.

  The biological information calculation unit 320 is a specific example of “calculation means”, and is generated according to the detection signal generated by each of the first light receiving element 211 and the second light receiving element 212 (that is, according to the intensity of received light). The pulsation period of the living body 500 is calculated based on the signal). Note that the biological information calculation unit 320 may calculate biological information other than the pulsation period as long as the biological information can be calculated from the detection signal. The calculated pulsation cycle is displayed on the display 330.

  Note that the measuring instrument 101 according to the present embodiment may be provided with other components such as input means for controlling the operation of the measuring instrument 101 in addition to the above-described components.

<1-2: Operation of measuring instrument>
Next, the operation of the measuring instrument according to the first embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing the operation of the measuring instrument according to the first embodiment.

  In FIG. 4, when the measuring instrument according to the present embodiment is operated, light is first irradiated from the light emitting element 201 to the living body 500 (step S101). The light emitted from the light emitting element 201 is reflected by the living body 500 and received by each of the first light receiving element 211 and the second light receiving element 212. Then, the first light receiving element 211 and the second light receiving element 212 generate detection signals according to the intensity of the received light (step S102). That is, two types of detection signals are separately generated by the first light receiving element 211 and the second light receiving element 212. The detection signal is output to the biological information calculation unit 320.

  In the biological information calculation unit 320, first, a sum signal and a difference signal of the detection signals are calculated (step S103). Specifically, the detection signal of the first light receiving element 211 and the detection signal of the second light receiving element 212 are added, and a sum signal is calculated. Further, the detection signal of the first light receiving element 211 and the detection signal of the second light receiving element 212 are subtracted to calculate a difference signal.

  Subsequently, the biometric information calculation unit 320 normalizes the sum signal and the difference signal (step S104). Specifically, the sum signal is normalized by being divided by the maximum value of the sum signal. Similarly, the difference signal is normalized by dividing by the maximum value of the difference signal. It is also possible to use other normalization methods.

  Subsequently, the biological information calculation unit 320 subtracts the normalized difference signal from the normalized sum signal (step S105). That is, a difference signal between the sum signal and the difference signal is calculated. Then, the biological information calculation unit 320 detects the frequency having the maximum amplitude in the calculated difference signal (step S106), and outputs the detected frequency as the pulsation cycle of the living body (step S107).

  Here, the sum signal and the difference signal calculated from the detection signal, and the difference signal thereof will be specifically described with reference to FIGS. FIG. 5 is a graph (part 1) showing an example of the sum signal, FIG. 6 is a graph (part 1) showing an example of the difference signal, and FIG. 7 is a graph showing the sum signal, the difference signal, and the difference signal. It is a graph (the 1) which shows an example. 8 is a graph (part 2) showing an example of the sum signal, FIG. 9 is a graph (part 2) showing an example of the difference signal, and FIG. 10 is a graph showing the sum signal, the difference signal, and the difference signal. It is a graph (the 2) which shows an example.

  In FIG. 5, the sum signal is obtained by adding the detection signal of the first light receiving element 211 and the detection signal of the second light receiving element 212. For this reason, in the normalized sum signal, the pulsation cycle of the living body 500 appears as a peak. In addition to the pulsation cycle, a peak due to body movement of the living body 500 also appears. Here, the left peak in the figure is shown as pulsation and the right peak as body movement, but at the stage when the sum signal is calculated, which peak is pulsation (that is, a value to be detected). Cannot be determined. Therefore, pulsation cannot be measured using only the sum signal. Or even if it can measure, it will become a thing with a low precision.

  In FIG. 6, the difference signal is obtained by subtracting the detection signal of the first light receiving element 211 and the detection signal of the second light receiving element 212. Here, in particular, the detection signal obtained from each of the first light receiving element 211 and the second light receiving element 212 includes the pulsation component and the body motion component of the living body, as can be seen from the sum signal shown in FIG. One pulsation component has a characteristic that does not vary with a slight difference in position of the light receiving element, whereas the other body movement component has a characteristic that varies with a slight difference in position of the light receiving element. For this reason, the detection signals obtained from each of the first light receiving element 211 and the second light receiving element 212 include pulsating components of the same degree, but include different body motion components. As a result, in the difference signal that is the difference between the detection signals, the pulsation component of the living body is canceled (offset), and only the body movement component of the living body remains. Therefore, according to the difference signal, only the body motion component can be extracted from a plurality of types of information included in the detection signal.

  In FIG. 7, when the difference signal is subtracted from the above-described sum signal, the body motion components included in each of the sum signal and the difference signal are canceled. As a result, only the pulsating component of the living body 500 remains in the differential signal. Therefore, the pulsation cycle of the living body 500 can be measured by detecting the frequency that is the maximum amplitude of the difference signal.

  In the waveforms shown in FIGS. 5 to 7, the pulsation cycle can be detected from the maximum amplitude of the sum signal without calculating the difference signal and the difference signal, but the maximum amplitude of the sum signal does not become a pulsation component. There may be cases.

  In the sum signal shown in FIG. 8, the peak of the left pulsation component in the figure appears smaller than the peak of the right body motion component in the figure. Therefore, when the maximum amplitude of the sum signal is detected in such a case, a body motion component that should not be measured is measured.

  However, as shown in FIG. 9, in the difference signal, the pulsation component is canceled and only the body motion component remains in the same manner as described above.

  Therefore, as shown in FIG. 10, if the difference signal between the sum signal and the difference signal is calculated, the body motion component is canceled and only the pulsation component remains. Therefore, it is possible to measure the pulsation cycle of the living body 500 by detecting the frequency that is the maximum amplitude of the difference signal.

  As described above, according to the measuring instrument according to the first embodiment, it is possible to extract only specific information from various types of information included in the detection signal. Therefore, it is possible to remove the body motion component unnecessary for measurement and accurately measure the pulsation cycle of the living body 500.

<2: Second embodiment>
Next, a measuring instrument according to the second embodiment will be described. The second embodiment differs from the first embodiment described above only in part of the configuration and operation, and is otherwise substantially the same. Therefore, in the following, differences from the already described first embodiment will be described in detail, and descriptions of overlapping points will be omitted as appropriate.

<2-1: Configuration of measuring instrument>
First, the configuration of the measuring instrument according to the second embodiment will be described with reference to FIG. 11 and FIG. FIG. 11 is a plan view showing the distance relationship between the light emitting element and the light receiving element of the measuring instrument according to the second embodiment. FIG. 12 is a plan view showing a modification of the measuring instrument according to the second embodiment.

  In FIG. 11, the measuring instrument according to the second embodiment is configured to include four light receiving elements, a first light receiving element 221, a second light receiving element 222, a third light receiving element 223, and a fourth light receiving element 224. . Here, the distance L 1 between the light emitting point of the light emitting element 201 and the light receiving point of the first light receiving element 221, the distance L 2 between the light emitting point of the light emitting element 201 and the light receiving point of the second light receiving element 222, and the light emitting point of the light emitting element 201 The distance L3 between the light receiving point of the third light receiving element 223 and the distance L4 between the light emitting point of the light emitting element 201 and the light receiving point of the fourth light receiving element 224 are equal to each other. Therefore, return light is incident on each of the first light receiving element 221, the second light receiving element 222, the third light receiving element 223, and the fourth light receiving element 224 under the same conditions.

  In FIG. 12, the first light receiving element 221, the second light receiving element 222, the third light receiving element 223, and the fourth light receiving element 224 do not have to have the same distances L1 to L4. And the light receiving point of the first light receiving element 221 and the distance L2 between the light emitting point of the light emitting element 201 and the light receiving point of the second light receiving element 222 are equal to each other, and the light emitting point of the light emitting element 201 and the third light receiving element The distance L3 between the light receiving point 223 and the distance L4 between the light emitting point of the light emitting element 201 and the light receiving point of the fourth light receiving element 224 may be arranged to be equal to each other.

  That is, the measuring instrument according to the second embodiment only needs to include two light receiving element pairs including two light receiving elements having the same distance from the light emitting element 201. Hereinafter, the first light receiving element 221 and the second light receiving element 222 having the same distance to the light emitting element 201 are referred to as a first light receiving element pair. Similarly, the third light receiving element 223 and the fourth light receiving element 224 are referred to as the second light receiving element. Called as a pair. Here, return light is incident on the two light receiving elements included in the first light receiving element pair under the same conditions. The two light receiving elements included in the second light receiving element pair also have the return light incident under the same conditions as those of the first light receiving element pair.

<2-2: Operation of measuring instrument>
Next, the operation of the measuring instrument according to the second embodiment will be described with reference to FIG. FIG. 13 is a flowchart showing the operation of the measuring instrument according to the second embodiment.

  In FIG. 13, when the measuring instrument according to the present embodiment is operated, light is first irradiated from the light emitting element 201 to the living body 500 (step S201). The light emitted from the light emitting element 201 is reflected by the living body 500 and received by each of the first light receiving element 221, the second light receiving element 222, the third light receiving element 223, and the fourth light receiving element 224. The first light receiving element 221, the second light receiving element 222, the third light receiving element 223, and the fourth light receiving element 224 generate detection signals in accordance with the intensity of the received light (step S202). That is, four types of detection signals are separately generated by the first light receiving element 221, the second light receiving element 222, the third light receiving element 223, and the fourth light receiving element 224. The detection signal is output to the biological information calculation unit 320.

  In the biological information calculation unit 320, first, an addition output and a subtraction output of the first light receiving element pair are respectively calculated (step S203). Specifically, the detection signal of the first light receiving element 221 and the detection signal of the second light receiving element 222 are added, and the added output is calculated. Further, the detection signal of the first light receiving element 221 and the detection signal of the second light receiving element 222 are subtracted to calculate a subtracted output.

  Similarly, the biological information calculation unit 320 calculates the addition output and the subtraction output of the second light receiving element pair, respectively (step S204). Specifically, the detection signal of the third light receiving element 223 and the detection signal of the fourth light receiving element 224 are added to calculate an added output. Further, the detection signal of the third light receiving element 223 and the detection signal of the fourth light receiving element 224 are subtracted to calculate a subtracted output.

  Subsequently, the biological information calculation unit 320 calculates a sum signal and a difference signal (step S205). Specifically, the addition output of the first light receiving element pair and the addition output of the second light receiving element pair are added to calculate a sum signal. Further, the subtraction output of the first light receiving element pair and the subtraction output of the second light receiving element pair are added to calculate a difference signal.

  Subsequently, the biometric information calculation unit 320 normalizes the sum signal and the difference signal (step S206). Specifically, the sum signal is normalized by being divided by the maximum value of the sum signal. Similarly, the difference signal is normalized by dividing by the maximum value of the difference signal. It is also possible to use other normalization methods.

  Subsequently, the biometric information calculation unit 320 subtracts the normalized difference signal from the normalized sum signal (step S207). That is, a difference signal between the sum signal and the difference signal is calculated. Then, the biological information calculation unit 320 detects the frequency having the maximum amplitude in the calculated difference signal (step S208), and outputs the detected frequency as the pulsation cycle of the living body (step S209).

  Here, in the second embodiment, unlike the first embodiment, four light receiving elements are provided. However, in each of the first light receiving element pair and the second light receiving element pair, the two light receiving elements are similar to each other. Return light is incident under certain conditions. Therefore, the sum signal obtained by adding the respective addition outputs of the first light receiving element pair and the second light receiving element pair includes both the pulsating component and the body moving component, as shown in FIGS. On the other hand, the difference signal obtained by adding the subtraction outputs of the first light receiving element pair and the second light receiving element pair includes only the body motion component as shown in FIGS. Therefore, the difference signal between the sum signal and the difference signal includes only the pulsation component as shown in FIGS.

  As described above, the measuring instrument according to the second embodiment can accurately measure the pulsation cycle of the living body 500 by removing body motion components unnecessary for measurement. In the second embodiment, in particular, the pulsation component and the body motion component can be extracted with high accuracy by the number of light receiving elements as compared with the first embodiment.

<3: Third embodiment>
Next, a measuring instrument according to the third embodiment will be described. The third embodiment differs from the first and second embodiments described above only in part of the configuration and operation, and is otherwise substantially the same. Therefore, in the following, differences from the already described first and second embodiments will be described in detail, and descriptions of overlapping points will be omitted as appropriate.

<3-1: Configuration of measuring instrument>
First, the configuration of the measuring instrument according to the third embodiment will be described with reference to FIG. FIG. 14 is a plan view showing the distance relationship between the light receiving elements of the measuring instrument according to the third embodiment.

  In FIG. 14, the measuring instrument according to the third embodiment includes four light receiving elements, a first light receiving element 231, a second light receiving element 232, a third light receiving element 233, and a fourth light receiving element 234. . Here, although the light emitting element 201 is not illustrated in FIG. 14, the light emitting element 201 is viewed from the first light receiving element 231, the second light receiving element 232, the third light receiving element 233, and the fourth light receiving element 234. It is arranged on the opposite side of 500. That is, the measuring instrument according to the third embodiment is a transmission type device. The light emitting element 201 is similar to the second embodiment described above in that the distance L1 between the light emitting point of the light emitting element 201 and the light receiving point of the first light receiving element 231 and the light emitting point of the light emitting element 201 and the second light receiving element 232 are the same. The distance L2 between the light receiving point, the light emitting point of the light emitting element 201 and the light receiving point of the third light receiving element 233, and the distance L4 between the light emitting point of the light emitting element 201 and the light receiving point of the fourth light receiving element 234 are They are placed at the same position. Therefore, return light is incident on each of the first light receiving element 231, the second light receiving element 232, the third light receiving element 233, and the fourth light receiving element 234 under the same conditions.

  In the measuring instrument according to the third embodiment, in particular, the first light receiving element 231, the second light receiving element 232, the third light receiving element 233, and the fourth light receiving element 234 are adjacent to each other at equal intervals when viewed in a plan view. Are arranged as follows. Specifically, the distance L5 between the light receiving point of the first light receiving element 231 and the light receiving point of the second light receiving element 232, the distance L6 between the light receiving point of the third light receiving element 233 and the light receiving point of the fourth light receiving element 234, the first The distance L7 between the light receiving point of the first light receiving element 231 and the light receiving point of the third light receiving element 233 and the distance L8 between the light receiving point of the second light receiving element 232 and the light receiving point of the fourth light receiving element 234 are equal to each other. Placed in position.

  In addition, since the measuring instrument according to the third embodiment is required to arrange four light receiving elements at relatively equal intervals in a relatively narrow space as described above, the light emitting element 201 is placed on a different plane from the light receiving element. Although a transmissive type device that can be arranged has been described as an example, if the light emitting element 201 can be arranged at the center of the light receiving element as in the second embodiment (see, for example, FIG. 11), it can also be configured as a reflective type device.

<3-2: Operation of measuring instrument>
Next, the operation of the measuring instrument according to the third embodiment will be described with reference to FIG. FIG. 15 is a flowchart showing the operation of the measuring instrument according to the third embodiment.

  In FIG. 15, when the measuring instrument according to the present embodiment is operated, light is first irradiated from the light emitting element 201 to the living body 500 (step S301). The light emitted from the light emitting element 201 passes through the living body 500 and is received by each of the first light receiving element 231, the second light receiving element 232, the third light receiving element 233, and the fourth light receiving element 234. Then, the first light receiving element 231, the second light receiving element 232, the third light receiving element 233, and the fourth light receiving element 234 generate detection signals according to the intensity of the received light (step S302). That is, four types of detection signals are separately generated by the first light receiving element 231, the second light receiving element 232, the third light receiving element 233, and the fourth light receiving element 234. The detection signal is output to the biological information calculation unit 320.

  In the biometric information calculation unit 320, first, of the four light receiving elements, the addition outputs related to two adjacent light receiving elements are calculated for each adjacent direction (step S303). Specifically, the detection signal of the first light receiving element 231 and the detection signal of the second light receiving element 232 are added for the adjacent in the vertical direction of FIG. 14 (hereinafter referred to as “one direction” as appropriate) 1 addition output is calculated. Further, the detection signal of the third light receiving element 233 and the detection signal of the fourth light receiving element 234 are added to calculate a second addition output. On the other hand, the detection signal of the first light receiving element 231 and the detection signal of the third light receiving element 233 are added for the adjacent in the left-right direction (hereinafter referred to as “other direction” as appropriate) in FIG. The output is calculated. Further, the detection signal of the second light receiving element 232 and the detection signal of the fourth light receiving element 234 are added, and a fourth addition output is calculated.

  Similarly, the biometric information calculation unit 320 calculates subtracted outputs related to two adjacent light receiving elements among the four light receiving elements, for each adjacent direction (step S304). Specifically, the detection signal of the first light receiving element 231 and the detection signal of the second light receiving element 232 are subtracted for the adjoining in the vertical direction in FIG. 14, and the first subtraction output is calculated. Further, the detection signal of the third light receiving element 233 and the detection signal of the fourth light receiving element 234 are subtracted to calculate a second subtracted output. On the other hand, the detection signal of the first light receiving element 231 and the detection signal of the third light receiving element 233 are subtracted for the adjoining in the left-right direction in FIG. 14, and a third subtraction output is calculated. Further, the detection signal of the second light receiving element 232 and the detection signal of the fourth light receiving element 234 are subtracted to calculate a fourth subtraction output.

  Subsequently, the biological information calculation unit 320 calculates a sum signal and a difference signal (step S305). Specifically, the first addition output and the second addition output are added to generate a sum signal related to one direction. In addition, the first subtraction output and the second subtraction output are added to generate a difference signal for one direction. Similarly, the third addition output and the fourth addition output are added to generate a sum signal in the other direction. In addition, the third subtraction output and the fourth subtraction output are added to generate a difference signal in the other direction. That is, a sum signal and a difference signal are generated for each of one direction and the other direction.

  Subsequently, the biometric information calculation unit 320 normalizes the sum signal and the difference signal (step S306). Specifically, the sum signal for one direction is divided by the maximum value of the sum signal for one direction, and the sum signal for the other direction is normalized by being divided by the maximum value of the sum signal for the other direction. The Similarly, the difference signal for one direction is divided by the maximum value of the difference signal for one direction, and the difference signal for the other direction is normalized by being divided by the maximum value of the difference signal for the other direction. It is also possible to use other normalization methods.

  Subsequently, the biological information calculation unit 320 subtracts the normalized difference signal from the normalized sum signal (step S307). Specifically, the difference between the sum signal related to one direction and the difference signal related to one direction is calculated, and the difference between the sum signal related to the other direction and the difference signal related to the other direction is calculated. That is, the difference between the sum signal and the difference signal is generated for each of one direction and the other direction. Then, the biological information calculation unit 320 detects the frequency having the maximum amplitude in the calculated difference signal (step S308), and outputs the detected frequency as the pulsation cycle of the living body (step S309). In the present embodiment, since the difference is calculated for each of one direction and the other direction, the pulsation period of the living body based on the difference regarding the one direction is calculated, and the pulsation period based on the difference regarding the other direction is calculated. Is also calculated. Note that the pulsation period calculated for each direction in this manner is selected and output, for example. Alternatively, a predetermined calculation (for example, calculation of an average value, etc.) is performed by using a pulsation cycle calculated based on a difference related to one direction and a pulsation cycle calculated based on a difference related to another direction. It is also possible to output a pulsation cycle based on both the difference regarding the direction of the other direction and the difference regarding the other direction.

  Here, in the third embodiment, unlike the first and second embodiments, the first to fourth addition outputs and the first to fourth subtraction outputs are calculated for the four light receiving elements in the adjacent directions, respectively. Since the adjacent distances of the four light receiving elements are equal to each other, the first to fourth addition outputs and the first to fourth subtraction outputs are calculated under the same conditions. The sum signal obtained by adding the first to fourth addition outputs includes both the pulsation component and the body motion component, as shown in FIGS. On the other hand, the difference signal obtained by adding each of the first to fourth subtraction outputs includes only the body motion component as shown in FIGS. Therefore, the difference signal between the sum signal and the difference signal includes only the pulsation component as shown in FIGS.

  As described above, according to the measuring instrument according to the third embodiment, it is possible to remove the body motion component unnecessary for the measurement and accurately measure the pulsation cycle of the living body 500. In the third embodiment, in particular, the addition output and the subtraction output are calculated for each adjacent direction, so that the pulsation component and the body motion component can be extracted with high accuracy.

  The present invention 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, and a measuring instrument with such a change is also included in the technical concept of the present invention.

DESCRIPTION OF SYMBOLS 101 Measuring instrument 111 Probe 201 Light emitting element 211,221,231 1st light emitting element 212,222,232 2nd light emitting element 223,233 3rd light emitting element 224,234 4th light emitting element 250 Light-shielding plate 310 Wiring part 320 Biological information calculation Part 330 display 500 living body

Claims (1)

A light emitting means for irradiating light;
A first light receiving means and a second light receiving means for receiving return light from the measurement target of the irradiated light;
The difference signal between the light received by the first light receiving means and the light received by the second light receiving means is subtracted from the sum signal of the light received by the first light receiving means and the light received by the second light receiving means. And a calculating means for calculating information on the measurement target based on the difference signal.

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