JP2006325766A - Biological signal measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biological signal measuring instrument for suppressing the light reception of light not transmitted through the vessel of a measurement object detected in a light receiving part low and realizing highly accurate biological signal measurement. <P>SOLUTION: One light receiving part 105 not measured yet among the plurality of light receiving parts is selected S801, the light receiving part 105 is made to function and measurement is performed S802. AC components and DC components are extracted from a measured value S803 and stored in a memory 107 S804. When the measurement of an AC-DC ratio is ended in all of the plurality of light receiving parts 105 in S805 (YES in S805), all the AC-DC ratios stored in the memory part in S804 are compared S805, and the light receiving part of the best value is selected S806. Since it is suitable for the measurement of an oxygen saturation when the AC (amplitude of signal) components are larger and the DC (DC of signal) components are smaller, the light receiving part where the value of AC-DC ratio is largest may be selected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biological signal measuring device that optically measures a biological signal such as a pulse wave and blood oxygen saturation from a blood vessel.

  For home medical care and preventive medical care, it is a device that can measure biological signals such as blood oxygen saturation and pulse in daily life. A biological signal measuring apparatus for measuring a signal has been proposed.

  Here, the blood oxygen saturation (also referred to as SpO2) is an index representing the amount of oxygen contained in the blood, and specifically, is bound to oxygen among the hemoglobin contained in the blood. Expressed as a percentage of things. As a method for measuring oxygen saturation, for example, pulse waves are measured by applying red light (λ1) and infrared light (λ2) of two different wavelengths to a blood vessel, and the oxygen saturation is calculated based on the obtained value. I can do it. The details of this method are as described in Non-Patent Document 1 described later.

Patent Document 1 described later includes a plurality of light emitting units each having a different light emitting region in order to increase the amount of received light that has passed through a blood vessel to be measured and obtain a pulse wave accurately. A technique is disclosed in which an optimum pulse wave can be measured by selecting a combination of light emitting units that irradiate light to the blood vessel to obtain the maximum AC component of the pulse wave. In addition, a technique is disclosed that increases the amount of light passing through a blood vessel by expanding the light emission range by irradiating all the light emitting units having a plurality.
Co-authored by Kenichi Yamakoshi and Tatsuo Togawa, edited by the Japanese Society of EM, “Biological Sensors and Measuring Devices”, Corona, October 25, 2002, p. 206-209 Japanese Patent Laid-Open No. 11-318840

  In Patent Document 1, an accurate measurement value is obtained by selecting a combination of light emitting units having a plurality of light emitting units having different light emitting areas and maximizing the AC component (amplitude) of the waveform obtained by the light receiving unit. However, it does not disclose a solution regarding the light receiving unit. Usually, the size of the light receiving portion in the thickness direction is too large compared to the thickness of the artery, and there is a problem that extra disturbing light that causes noise is received.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a biological signal measuring device that realizes highly accurate biological signal measurement by suppressing light reception of light that does not pass through a blood vessel to be measured detected by a light receiving unit. To do.

  In order to solve the above problems, a biological signal measuring apparatus according to a first aspect of the present invention includes a detection unit including a light emitting unit and a light receiving unit, and includes a detection unit including a light emitting unit and a light receiving unit. The size in the thickness direction of the blood vessel that is the measurement target of the light reception detection region was set to 1 mm or more and 2 mm or less. Thereby, the light which does not pass through the blood vessel of the measurement object received by the light receiving unit can be reduced, and the measurement accuracy can be improved.

  The biological signal measurement device according to the second aspect of the present invention further includes a plurality of the light receiving units in a direction perpendicular to the traveling direction of the blood vessel, and at least one of the signals obtained by the plurality of light receiving units. There is a biological signal selection means for selecting one of them and measuring the biological signal. This makes it possible to avoid the deterioration of measurement accuracy due to deviation due to daily life and to obtain higher-accuracy measurement values by selectively using the light-receiving unit that has received light correctly even when wearing deviation occurs. it can.

  Furthermore, the biological signal selection unit selects the light receiving unit based on the amplitude of the signal obtained by the light receiving unit. The plurality of light receiving units are arranged so as to be distributed two-dimensionally. Thereby, it is possible to perform measurement with higher accuracy more reliably.

  Further, the plurality of light receiving units are arranged in a lattice shape parallel and perpendicular to the traveling direction of the blood vessel to be measured, and further arranged while shifting the columns in the vertical direction with respect to the traveling direction of the blood vessel to be measured. To do. This increases the probability that there is a light receiving unit that can receive light correctly, and enables more accurate measurement.

  Further, the plurality of light receiving units are arranged so as to be densely arranged at a plurality of locations at locations away from the traveling direction of the blood vessel to be measured. Thereby, even when the blood vessel to be measured is meandering, accurate measurement can be performed.

  A biological signal measuring apparatus according to a third aspect of the present invention includes a detection unit including a light emitting unit and a light receiving unit, and a measurement processing unit that measures a biological signal based on an output from the detection unit. A plurality of light-receiving portions whose size in the direction perpendicular to the running direction of the target blood vessel is sufficiently small with respect to the diameter in the thickness direction of the blood vessel, arranged in a direction perpendicular to the running direction of the blood vessel to be measured; Selects a light-receiving unit in an effective area from a plurality of light-receiving units, and performs measurement processing according to a signal from the selected light-receiving unit. Thereby, it becomes possible to avoid the deterioration of the measurement accuracy due to the deviation due to daily life.

  Furthermore, in particular, when the ring type is attached to the fingers, it is possible to always measure the biological signal without disturbing daily life.

  According to the first aspect of the present invention, it is possible to accurately measure a biological signal by reducing the influence of disturbance light that becomes a measurement inhibiting factor.

  According to the 2nd aspect of this invention, the tolerance | permissible_range of the mounting state of the biosignal measuring apparatus which can measure a biosignal correctly can be expanded by providing a some light-receiving part. In addition, it is possible to allow positional deviation due to body movement of the biological signal measuring device.

  According to the third aspect of the present invention, there is provided a biological signal measuring apparatus that includes a plurality of light receiving units that are sufficiently smaller than a blood vessel diameter to be measured, and that can selectively measure a biological signal by selectively using a part thereof. The allowable range of the wearing state can be widened, and it is possible to allow a positional shift due to body movement of the biological signal measuring device. Furthermore, appropriate measurement can be performed without being affected by individual differences in the thickness of blood vessels. In addition, since it is possible to cope with individual differences, it is possible to reduce the influence of disturbance light, which becomes a measurement inhibiting factor, and to measure biological signals more accurately.

(First embodiment)
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In the drawings used in the following description, the same parts or the same functions are denoted by the same reference numerals. Therefore, detailed description thereof will not be repeated.

  In the first embodiment of the present invention exemplified below, as a biological signal measuring device that irradiates a blood vessel to be measured from a light emitting unit and measures a biological signal by a signal obtained by the light receiving unit, A ring type biological signal measuring device (hereinafter simply referred to as “human body wearing sensor”) that wears and measures a pulse wave and oxygen saturation from a finger artery will be described as an example. According to this configuration example, since the wearing location is a finger, it is possible to always measure a biological signal without disturbing daily life. As described above, the human body wearing sensor is a device that is almost always worn on the user's finger and measures oxygen saturation, pulse, blood pressure, etc. from the pulse wave constantly or intermittently. Note that the configuration described below is not limited to a ring type or the like, and can be applied to any biological signal measuring apparatus that measures a biological signal using a signal obtained from a light receiving unit that is in close contact with a living body with a blood vessel as a measurement target. is there.

  FIG. 1 schematically shows a cross-sectional view of the human body wearing sensor 100 and fingers. As shown in the figure, the human body wearing sensor 100 in the present embodiment has an annular shape, and a light emitting unit 104 and a light receiving unit 105 are provided on the inner periphery thereof. The intrinsic palmar finger artery 102 is an artery on the ventral side (palm side) of the finger 101 and is a measurement target of the human body mounting sensor, and the bone 103 is mounted by the human body mounting sensor 100 at a position where a normal ring is mounted. If it is, it becomes the proximal phalanx. There are two (102-a, 102-b) unique palmar finger arteries 102 on the ventral side of the finger of the bone 103 in each of the index finger to the ring finger. The artery 102 to be measured is irradiated with light from the light emitting unit 104, and the light passing through the living tissue including the artery 102 is received by the light receiving unit 105. Here, an LED (Light Emitting Diode) is used as the light source of the light emitting unit 104, and a PD (Photo Diode) is used as the light receiving element of the light receiving unit 105. In addition, the light receiving unit 105 is configured to be in close contact with the finger 101 with an appropriate pressing force so that the pulsation of the artery 102 increases.

  Since the artery 102 pulsates in accordance with the heartbeat, the light absorption by hemoglobin fluctuates in synchronization with the heartbeat, and the amount of light received through the artery 102 in the light receiving unit 105 also changes. Arise. As shown in Non-Patent Document 1, in measuring oxygen saturation, the difference in absorbance due to hemoglobin in the artery 102 is used by using light of two different wavelengths, red light and infrared light. At this time, it is known that an approximate value of the oxygen saturation can be obtained based on the ratio of the ratio of the AC component to the DC component at two wavelengths (called Ratio of ratio). Therefore, more accurate measurement is possible in an environment where AC / DC is a large value. As shown in FIG. 12, the AC component here refers to the amplitude component of the signal, and the DC component refers to the DC component that is the average value of the signal.

  FIG. 2 shows how the inner diameter of the artery 102 expands and contracts due to pulsation. Thus, the artery when expanded due to the pulsation caused by the change in blood flow caused by the pulsation of the heart is shown as 102-w, and the artery when contracted (steady state) is shown as 102-s. In addition, the inner diameters in the direction parallel to and perpendicular to the light receiving surface of the light receiving unit 105 when expanded are Wmax and Lmax, respectively, and the direction parallel to and perpendicular to the light receiving surface of the light receiving unit 105 when contracted The inner diameter of each is Wmin and Lmin.

  In the present embodiment, the size of the light receiving unit 105 in the thickness direction of the artery is 1.3 mm. Hereinafter, the reason why such a size is used will be described with reference to the drawings.

  FIG. 3 shows a model of only a part of the human body wearing sensor 100 and the finger 101 when the human body wearing sensor 100 is worn, and the vicinity of the artery 102 to be measured and the light receiving unit 105. 3 patterns are shown for each of the light receiving portions 105 of different sizes. More specifically, in (a) to (c) of FIG. 3, the size (detectable region) in the thickness direction of the blood vessel to be measured by the light receiving unit 105 is set to 3 with respect to the inner diameter of the artery 102. It has been changed to a kind.

  First, FIG. 3A shows a case where the size in the thickness direction of the blood vessel to be measured by the light receiving unit 105 is equal to or smaller than the inner diameter in the vertical direction of the blood vessel contraction 102a-s, that is, Wmin. The light emitted from the human body wearing sensor attached to the finger 101a to the artery 102a to be measured from the light emitting unit 104a is indicated by a horizontal solid line 106a. Since the light receiving portion 105a is smaller than the inner diameter of the contracting artery 102a-s as shown in the figure, among the light 106a emitted from the light emitting portion 104, the light received through the artery 102a is indicated by a dotted line 107a. It becomes. In practice, light is diffused by cells and other tissues, but the intrinsic palmar finger artery 102 as a measurement target is in a shallow position, so the distance between the detection unit 105 and the artery 102 as a measurement target. (D in FIG. 1) becomes smaller, and modeling in which light goes straight through the inside of the illustrated finger becomes possible. Furthermore, since the detection unit 105 is pressed against the finger as described above during measurement, d in FIG. 1 becomes smaller.

  Next, FIG. 3B shows a case where the size of the light receiving portion 105 is larger than the contracted inner diameter Wmin and smaller than the expanded inner diameter Wmax. In this case, the light receiving area 107b expands as compared with (a) as indicated by the dotted line area. Further, since the size of the light receiving unit 105b is between the contracted inner diameter Wmin and the expanded inner diameter Wmax in the blood vessel thickness direction, the pulsation in the blood vessel thickness direction (Wmax-Wmin) can also be detected, and changes due to the pulsation can be captured. It becomes easy.

  Finally, FIG. 3C shows a case where the size of the light receiving portion 105 is made larger than the expanded inner diameter Wmax. In this case, since the light receiving portion 105c is larger than the inner diameter Wmax of the dilated artery 102c-w, even the incident light 106c that does not pass through the artery 102c is always received. Of the light receiving unit 105c, light that does not pass through the artery 102c, that is, a portion that receives noise light is indicated by hatching. As the size of the light receiving unit 105c increases, the hatched area increases.

  FIG. 4 shows the relationship between the size of the light receiving unit 105 and the signal intensity. First, the case where the size of the light receiving portion 105 is shown in FIG. 3A is the case where Wmin (inner diameter during contraction) or less in the drawing. In this case, as the size of the PD increases, the strength of the received signal increases as a whole, so that each of the AC component and the DC component increases at a constant increment. However, the artery 102a changes due to the pulsation to the contraction artery 102a-s and the dilation artery 102a-w. However, since the size of the light receiving portion 105a is smaller than the contraction inner artery inner diameter Wmin, the amount of light received by the pulsation in the light receiving portion 105a. The fluctuations are caused only by fluctuations in the light path length (Lmin, Lmax in FIG. 2).

  Next, in the case where the size of the light receiving unit 105 is FIG. 3B, in the AC component, fluctuation due to both the light amount change due to the path length change due to the above-described Lmin and Lmax and the light amount change due to the blood vessel widths Wmin and Wmax. Therefore, as the size of the light receiving unit 105 increases, the AC component, which is the fluctuation range, increases with a steeper slope than in the case of (a). On the other hand, when the artery 102b contracts, the component that does not pass through the artery 102b is also received when the artery 102b contracts, so that the increase rate of the DC component increases compared to the case of (a).

  Finally, when the size of the light receiving unit 105 is as shown in FIG. 3C, the DC component increases because the noise light increases as the size of the light receiving unit 105c increases, whereas the AC component is increased by the light receiving unit 105c. Even if it becomes larger than the dilated artery 102c-w, the size of the area 107c that passes through the artery 102c and receives light does not become larger than the dilated artery 102c-w, so the value of the AC component is constant.

  As described above, if the size of the light receiving unit 105 is too small, fluctuation due to pulsation cannot be detected. Conversely, if the size of the light receiving unit 105 is too large, light that does not pass through the artery 102 that is a measurement target is noise light. It is understood that the DC component is increased and the measurement accuracy is deteriorated due to a quantization error or the like from the above-described calculation formula. In addition, if the size of the light receiving unit 105 is too large, disturbance light including frequency components such as a fluorescent lamp may hinder accurate measurement. Furthermore, an increase in the size of the light receiving unit 105 causes an increase in the junction capacitance of the diode, resulting in a poor frequency response and an increase in the pulse driving width of the LED, which leads to an increase in power consumption.

  Therefore, the size of the light receiving unit 105 can best detect the fluctuation of the signal due to pulsation in the AC component, and can suppress the DC component that does not pass through the artery 102, the disturbance light noise component, and the junction capacitance to the minimum. A highly accurate measurement value can be obtained by adding a margin to the size. As described above, the size of the light receiving unit 105 in the thickness direction in the present embodiment in the thickness direction of the artery is a size obtained by further adding a margin so as to allow individual differences and positional deviations. It is possible to obtain a highly accurate measurement value by keeping the DC component detected by the unit low. Preferably, the size of blood vessels including individual differences is 1 mm, and the range of displacement due to body movement is also 1 mm. Therefore, it is preferably about 1 to 2 times Wmax, that is, about 1 mm to 2 mm. Here, the size is 130% of Wmax and 1.3 mm.

In this embodiment, as shown in FIG. 1, the light receiving unit 105 is installed in the vertical direction (Wmin, Wmax), but is installed in the horizontal direction (Lmin, Lmax). In this case, similarly, by setting the size of the light receiving unit 105 to the expanded inner diameter Lmax, it is possible to obtain a highly accurate measurement value with the maximum AC component and the minimum DC component. Note that the diameter of a normal blood vessel that is not pressurized may be used as an approximate value of Wmax.
(Second Embodiment)
In the first embodiment, since the distance between the artery 102 to be measured and the light receiving unit (distance d in FIG. 1) is small, the size 105 of the light receiving unit 105 is set to Wmax, and individual differences and positional deviations are allowed. It has been explained that a highly accurate measurement value can be obtained by setting the thickness to 1.3 mm with a margin added. However, assuming that the human body wearing sensor 100 is worn in daily life, there is a possibility that the wearing deviation due to various body movements may occur, and the light receiving unit 105 itself is greatly displaced from the artery 102 to be measured. there is a possibility. In the present embodiment, a plurality of the light receiving sections 105 having the sizes that can obtain the optimum measurement values shown in the first embodiment are arranged so that the two-dimensionally distributed light receiving areas include the vicinity of the blood vessel to be measured. A description will be given of a configuration in which a more accurate measurement value can be obtained by selectively using the light receiving unit 105 that has received light correctly even when a mounting deviation occurs.

  FIG. 5 is a layout view when nine light receiving portions 105 are arranged as a group light receiving portion. In the light receiving units 105-1 to 105-9, the light receiving areas are arranged in a lattice shape parallel to and perpendicular to the traveling direction of the blood vessel. In particular, the lattice is only in the traveling direction of the blood vessel to be measured. Align them slightly. More specifically, the light receiving portions 105 are arranged side by side in a direction approximately perpendicular to the direction of blood flow, and the light receiving portions above each of the directions parallel to the direction of blood flow. Each of the light receiving portions 105 is arranged at a position shifted by one third from the width of 105. The size of the light receiving unit 105 in the thickness direction of the blood vessel is preferably about 150% of the aforementioned Wmax, that is, about 1.5 mm in consideration of individual differences and positional deviation. Thus, the size is slightly larger than the diameter when the blood vessel is expanded, and the nine light receiving sections 105-1 to 105-9 are slightly different from each other (33% in the lateral direction). Since the artery 102 is linearly running in the vertical direction in the figure because it is displaced, even if it moves from the light receiving part 105-n where there is a region that can receive light well, Since the light receiving unit 105 can receive light well, by selecting the light receiving unit 105 that can receive light well, a detection value with a large amount of light that has passed through the artery 102, that is, the AC component has a maximum DC. Measurement of oxygen saturation and the like can be performed with measurement values with less components (noise), and high-accuracy measurement can be realized.

  FIG. 6 shows a functional configuration diagram of the human body wearing sensor 100 in the present embodiment. As shown in the figure, the human body wearing sensor 100 is mainly composed of a detection unit 103 and a measurement processing unit 108. The detection unit 103 determines the light receiving unit 104, a group light receiving unit including a plurality of light receiving units 105 (n = 9 in the case of FIG. 5), and a light receiving unit connected to the light receiving unit 105 and used for measurement. And a memory unit 107 connected to the light receiving unit determining unit. Next, the measurement processing unit 108 is connected to the light receiving unit determination unit. The memory unit 107 is a memory that stores measurement values obtained by the respective light receiving units 105 when the light receiving unit determination unit 106 determines the light receiving units, and the light receiving unit determination unit 106 selects the optimum light receiving unit. 105 is determined, and the measurement value by the determined light receiving unit 105 is notified to the measurement processing unit 108. The measurement processing unit 108 performs a biological signal measurement process based on the signal obtained by the light receiving unit 105, such as calculation of oxygen saturation.

  FIG. 7 is a flowchart showing a processing flow of the light receiving unit determination unit 106. First, an unmeasured light receiving unit 105 is selected from a plurality of light receiving units (S801), and the light receiving unit 105 is operated to perform measurement (S802). An AC component and a DC component are extracted from the measured value (S803), stored in the memory 107 (S804), and when the AC-DC ratio has been measured in all the plurality of light receiving units 105 in S805 (YES in S805). In step S804, all AC-DC ratios stored in the memory unit 107 are compared (S805), and the light receiving unit having the best value is selected (S806).

  FIG. 8 shows an example of AC component and DC component data measured from each of the plurality of light receiving units 105 stored in the memory 107. The AC-DC ratio column at the right end is a value obtained by dividing the AC component obtained by each light receiving unit by the DC component. Since the larger the AC component and the smaller the DC component, the more suitable the oxygen saturation measurement is, the light receiving unit determining unit 106 should select the light receiving unit having the largest AC-DC ratio value in the rightmost column. Good. Thereafter, the measurement value received by the selected light receiving unit 105 (for example, light receiving unit-1 in FIG. 6) is notified to the measurement processing unit 108, and the other light receiving units (light receiving unit-2 to light receiving unit-n). Stops the light receiving function and does not adopt it as a measurement value.

  The timing at which the light receiving unit determination unit 106 determines the best light receiving unit 105 is preferably immediately before the measurement processing unit 108 performs measurement.

  Furthermore, in the above-described S801, measurement is performed by causing the light receiving unit 105 to function one by one in order among the plurality of light receiving units, but of course, measurement from a plurality of light receiving units may be performed simultaneously.

  In addition, the group light receiving units shown in FIG. 5 are regularly arranged in a lattice shape while shifting only in the traveling direction of the blood vessels, but any of the light receiving units 105 may be randomly arranged in a plane so as not to overlap. Such a light receiving unit is likely to receive light appropriately, and an effect of improving measurement accuracy can be expected.

  In addition, the light receiving unit determining unit 106 selects the light receiving unit having the largest AC-DC ratio value in the rightmost column, but may simply select the light receiving unit 105 having the largest AC value.

As described above, since the best one is selected from the plurality of light receiving portions 105 of the group light receiving portions arranged by shifting the detection areas, depending on the displacement during wearing and the difference in position of the artery 102 depending on the individual. However, the best measurement is possible.
(Third embodiment)
In the second embodiment, by arranging a plurality of the light receiving portions 105 so as to be different light receiving regions little by little, the light receiving portions 105 that have received light correctly even when mounting displacement occurs can be selectively performed. A configuration has been described in which it is possible to obtain a more accurate measurement value by using it.

  However, the second embodiment is based on the premise that the blood vessel to be measured runs linearly, and does not operate effectively when the blood vessel is meandering. The biological signal measuring apparatus 100 according to the present embodiment will be described with respect to the configuration of the human-body-mounted sensor 100 that improves the possibility that an accurate biological signal can be measured even when a deviation occurs when a blood vessel is meandering.

  FIG. 9 shows a layout of the light receiving unit 105 of the human body wearing sensor 100 according to the present embodiment.

  As shown in the figure, in the human-body-mounted sensor 100 according to the present embodiment, the group light receiving units arranged so that the plurality of light receiving units 105 are densely arranged in a lattice pattern are separated from each other by a distance in the blood vessel traveling direction. It is provided at two locations. Although not shown, two light emitting units 104 are provided for each of the two group light receiving units.

  FIG. 10 shows a functional configuration diagram of the human body wearing sensor 100 in the present embodiment. As shown in the figure, the human body wearing sensor 100 is mainly composed of a detection unit 103 and a measurement processing unit 108. The detection unit 103 includes two group light receiving units composed of a plurality of light receiving units 105 (n = 9 in the case of FIG. 5), two light emitting units 104A and 104B for each group light receiving unit, and two Light receiving unit determination units 106A and 106B for determining a light receiving unit to be used for measurement connected to the light receiving unit 105 of each group light receiving unit, memory units 107A and 107B connected to the respective light receiving unit determination units, A group light receiving unit determining unit 109 that determines which output of the light receiving unit determining units 106A and 106B connected to each group light receiving unit is used for measurement is configured.

  The two light receiving unit determination units 106A and 106B of the human body wearing sensor 100 according to the present embodiment perform the operations up to S806 in the operation flow described in FIG. The group light receiving unit determination unit 109 is notified of the AC-DC ratio of the light receiving unit. The group light receiving unit determination unit 109 determines to use the output from the light receiving unit determination unit with the better AC-DC ratio notified, that is, the larger value, and in the measurement process, the measurement The output from the light receiving unit determination unit is relayed to the processing unit 108.

  The group light receiving units shown in FIG. 9 are regularly arranged in a lattice pattern while being displaced only in the blood vessel traveling direction, but the respective light receiving units 105 are not overlapped in each group light receiving unit region. Even if they are randomly arranged in a plane, there is a high possibility that light is received appropriately in any of the light receiving sections, and an effect of improving measurement accuracy can be expected.

  Further, in selecting the best light receiving unit 105, the group light receiving unit determines two best light receiving units 105 in accordance with the flow of FIG. 7 and compares them, and S801 in the flow of FIG. 7 is used. From S to S805, it goes without saying that the light receiving units 105 included in both the group light receiving units may be measured and compared.

As described above, since there are two group light receiving portions that are separated from each other in the substantially traveling direction of the blood vessel, even if the artery is meandering instead of being straight, any one of the plurality of light receiving portions 105. Is likely to match the position of the artery 102. Furthermore, although the number of group light-receiving units shown in the present embodiment is two, the number is not limited to this number and may be larger.
(Fourth embodiment)
In the above-described embodiment, the size in the thickness direction of the blood vessel to be measured of the light receiving element itself of the light receiving unit 105 is about 1 to 2 times Wmax when the blood vessel is expanded, that is, about 1 mm to 2 mm. By doing so, the DC component detected by the light receiving unit is suppressed to a low level to achieve highly accurate measurement, and the plurality of light receiving units 105 are provided, thereby avoiding deterioration in measurement accuracy due to deviation due to daily life.

  In this embodiment, the deterioration of measurement accuracy due to deviation due to daily life is achieved by realizing a high-accuracy measurement by suppressing the DC component low, and further by providing a plurality of the light receiving units 105, This will be described with reference to the drawings.

  FIG. 11 shows a layout of the light receiving unit 105 of the human body wearing sensor 100 according to the present embodiment.

  As shown in the figure, in the human body wearing sensor 100 according to the present embodiment, a plurality (N) of light receiving portions 105 elongated in the running direction of the artery 102 to be measured are perpendicular to the running direction of the blood vessel. A group light receiving portion arranged in a line in the direction is provided. The size of the light receiving unit 105 in the thickness direction of the blood vessel is sufficiently shorter than the diameter in the thickness direction of the blood vessel. The size of the light receiving unit 105 in the thickness direction of the blood vessel in the present embodiment is about 1/20 of the diameter in the thickness direction of the blood vessel, that is, about 0.05 mm. Further, the number of the light receiving portions 105 is 100 (N = 100). That is, the size in the thickness direction of the blood vessel in the entire group light receiving unit composed of the plurality of light receiving units 105 is about 5 mm, and it is possible to cope with individual differences such as a larger positional deviation and the thickness of the blood vessel. The size of the light receiving unit 105 in the running direction of the blood vessel is 1 mm.

  The functional configuration diagram of the human body wearing sensor 100 in the present embodiment is the same as that of FIG. 10 shown in the second embodiment, and is largely configured by the detection unit 103 and the measurement processing unit 108. The detection unit 103 includes the light-emitting unit 104, a group light-receiving unit including a plurality of light-receiving units 105, and a light-receiving unit determining unit 106 that determines a light-receiving unit connected to the light-receiving unit 105 of the group light-receiving unit and used for measurement. And a memory unit 107 connected to the light receiving unit determining unit.

  The light receiving unit determination unit 106 of the human body wearing sensor 100 according to the present embodiment performs the processing up to S805 in FIG. 7 of the second embodiment, and creates a table similar to FIG. 8 in the memory unit 107. To do. In this table, suffixes are assigned from the first in the order in which the plurality of light receiving portions 105 are physically arranged. Next, a combination of integers n and m that maximizes the value of α defined by Equation 1 is searched. Since this technique is known as a brute force technique, the detailed description thereof will not be repeated here. Note that N ≧ m> n> 0.

  Based on the values of n and m that maximize α in Expression 1 obtained by the above processing, the light receiving unit determination unit 106 only includes the (m−n + 1) light receiving units 105 from the n-th to the m-th. , And the measurement processing unit 108 is notified of the sum of these ac and dc values.

  Alternatively, a part of the plurality of light receiving units that can detect a signal from the measurement target can be effectively measured by the switch circuit.

  In addition, the method of selecting a part of the light receiving units from the plurality of light receiving units described above is an example, and in addition, an average size at the time of vascular dilation is cut out mainly in an area where the rate of change in the amount of received light due to pulsation is high. Alternatively, a method of selecting a light receiving unit in which each AC / DC value is a predetermined value or more, or selecting a light receiving unit in which only the AC value is a predetermined value or more may be used.

  As described above, the human body wearing sensor 100 according to the present embodiment arranges a large number of the light receiving units 105 in a row in a direction perpendicular to the traveling direction of the blood vessel 102, and the total number of the light receiving units 105 is determined from the light receiving units 105. Since the subset with the best AC-DC ratio is selected, the best measurement is possible even if there is a deviation during wearing or the position of the artery 102 varies between individuals.

It is sectional drawing of the human body mounting | wearing sensor which concerns on the 1st Embodiment of this invention, and a mounting finger. It is sectional drawing of the artery used as a measuring object. It is the figure which showed typically the relationship between the light-receiving part of the human body wearing sensor which concerns on the 1st Embodiment of this invention, and an artery. It is the graph which showed the relationship between the size of the light-receiving part of the human body wearing sensor which concerns on the 1st Embodiment of this invention, and signal strength. It is a permeation figure of a human body wearing sensor and a wearing finger concerning a 2nd embodiment of the present invention. It is a block diagram of a human body wearing sensor concerning a 2nd embodiment of the present invention. It is the flowchart which showed the flow of the process of the light-receiving part determination part of the human body mounting sensor which concerns on the 2nd Embodiment of this invention. It is the figure which showed the table stored in the memory of the human body mounting sensor which concerns on the 2nd Embodiment of this invention. It is a permeation | transmission figure of the human body mounting | wearing sensor which concerns on the 3rd Embodiment of this invention, and a mounting finger. It is a block diagram of a human body wearing sensor concerning a 3rd embodiment of the present invention. It is a permeation | transmission figure of the human body mounting | wearing sensor which concerns on the 4th Embodiment of this invention, and a mounting finger. It is a figure explaining an AC component and a DC component.

Explanation of symbols

100 Human Body Sensor 101 Finger 102 Arteries 102a-w, 102b-w, 102c-w Arteries 102a-s, 102b-s, 102c-s at the time of expansion Arteries 103 at the time of contraction 103 Bone 104 Light emitting unit 105 Light receiving unit 106 Light receiving unit determining unit 107 Memory 108 Measurement processing unit 109 Group light receiving unit determination unit

Claims (8)

A biological signal measuring device that irradiates a blood vessel to be measured from a light emitting unit and measures a biological signal by a signal obtained by a light receiving unit,
A detection means comprising a light emitting part and a light receiving part
The biological signal measuring apparatus according to claim 1, wherein a size of a blood vessel which is a measurement target of the light receiving detection region of the light receiving unit is 1 mm or more and 2 mm or less.   A plurality of the light receiving units in a direction perpendicular to a running direction of the blood vessel, and a biological signal selection unit configured to select at least one of the signals obtained by the plurality of light receiving units and measure a biological signal. The biological signal measuring device according to claim 1.   The biological signal measuring apparatus according to claim 2, wherein the biological signal selection unit selects the light receiving unit based on an amplitude of a signal obtained by the light receiving unit.   The biological signal measuring apparatus according to claim 2 or 3, wherein the plurality of light receiving units are arranged so as to be two-dimensionally distributed.   The plurality of light receiving units are arranged in a lattice shape parallel to and perpendicular to the traveling direction of the blood vessel to be measured, and further arranged while shifting the columns in the vertical direction with respect to the traveling direction of the blood vessel to be measured. The biological signal measuring apparatus according to claim 4, wherein:   The biological signal measuring device according to claim 4, wherein the plurality of light receiving units are arranged so as to be densely arranged at a plurality of locations at a location distant from a traveling direction of a blood vessel to be measured. A biological signal measuring device that irradiates a blood vessel to be measured from a light emitting unit and measures a biological signal by a signal obtained by a light receiving unit,
Detection means comprising a light emitting part and a light receiving part;
Measurement processing means for measuring a biological signal based on the output from the detection means,
The light receiving unit has a plurality of light receiving units arranged in a direction perpendicular to the traveling direction of the blood vessel to be measured, the size of the direction perpendicular to the traveling direction of the blood vessel to be measured being sufficiently small with respect to the diameter in the thickness direction of the blood vessel. And
The measurement processing unit selects a light receiving unit in an effective area from the plurality of light receiving units, and performs a measurement process according to a signal from the selected light receiving unit.
A biological signal measuring device.   The biological signal measuring device according to any one of claims 1 to 7, wherein the biological signal measuring device is a ring type attached to a finger.

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