JP2000083914A - Biological information measuring device and pulse wave measuring device - Google Patents

Abstract

(57) [Problem] To provide an optical human body information detecting device and a pulse wave measuring device capable of relaxing restrictions on use conditions without a large-scale light shielding structure. SOLUTION: In a pulse wave measuring device 1, a device main body 10 is mounted on an arm with a wrist band 12, and a detecting device 30 is mounted on a finger with a sensor fixing band 40. In this state, when light is emitted from the LED 31 toward the finger, the light reaches the blood vessel and is reflected. The reflected light is received by the phototransistor 32, and the amount of received light corresponds to a change in blood volume caused by a pulse wave of blood. Where L
The ED 31 uses a blue LED, and its emission wavelength peak is 450 nm. The light receiving wavelength region of the phototransistor 32 is in a wavelength region from 300 nm to 600 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a living body information measuring apparatus such as a pulse wave measuring apparatus, and more particularly, to irradiating a living body with light and detecting reflected light from the living body to detect a living body such as a pulse wave. The present invention relates to a device for measuring information.

[0002]

2. Description of the Related Art As a device for measuring biological information such as a pulse wave, there is an electronic device that optically detects a change in the amount of blood and displays the biological information based on the detection result. In such an optical pulse wave measuring device (biological information measuring device), an LED is used.
Light is emitted from a light-emitting element such as a light-emitting diode (LED) to a fingertip or the like, and reflected light from a living body (blood vessel) is received by a light-receiving element such as a phototransistor. The change in the pulse rate and the pulse wave are displayed based on the pulse wave signal obtained thereby, and the light emitted from the light emitting element has conventionally been infrared light. ing. Here, when external light (sunlight) enters the light receiving element, the amount of received light fluctuates in accordance with the fluctuation of the amount of incident external light. Therefore, in a conventional pulse wave measurement device, a detection part such as a fingertip is shielded. The effect of external light is suppressed by covering with a cover.

[0003]

However, in the conventional pulse wave measuring apparatus, even if the light shielding cover for external light is large, if it is used in a place exposed to external light, such as outdoors, a part of the external light may become a finger itself. There is a disadvantage that erroneous detection of a pulse wave is liable to occur due to fluctuations in the illuminance of external light when the light reaches the light receiving element through the light receiving element. Therefore, the conventional pulse wave measurement device has a restriction that it can be used only in a place where external light does not hit or a place where the illuminance of the external light is constant.To alleviate such a restriction, a larger light-shielding structure is required. As a result, the pulse wave measuring device cannot be downsized. In order to solve such a problem, Japanese Utility Model Application Laid-Open No. 57-74
No. 009 discloses a pulse wave sensor that includes an external light detection element that detects external light in addition to a pulse wave detection device, and that compensates for the influence based on the result of detection of external light by the external light detection element. Have been. However, the provision of an external light detection element and a compensation circuit in the pulse wave sensor hinders downsizing and cost reduction. poor.

[0004] In view of such problems, the present inventor has conducted various studies on the reason why erroneous detection of a pulse wave occurs due to fluctuations in the illuminance of external light. This is because the infrared light used in the detection system has a too high transmittance in the living body, so that even if the light-shielding cover is attached, the external light easily passes through the living body itself and reaches the light receiving element. It was concluded that practical solutions to external light would be possible if resolved.

[0005] Therefore, an object of the present invention is to provide a biological information detecting apparatus and a pulse wave measuring apparatus which can use optical systems which are hardly affected by external light and which can reduce restrictions on use conditions without a large light shielding structure. Is to provide.

[0006]

According to the present invention, there is provided a light emitting unit for irradiating light to a part of a living body, and receiving light emitted from the light emitting unit through the living body. A living body information measuring device having a light receiving unit that performs light receiving, that is, a detecting unit including a light receiving unit that receives reflected light from a living body, and a biological information displaying unit that displays biological information based on a detection result of the detecting unit; It is characterized in that information is displayed based on the detection result of the detection means in the wavelength region from about 300 nm to about 700 nm.

In performing detection in such a wavelength range, for example, the emission wavelength range of the light emitting section is set to at least about 3
When the wavelength range is from 00 nm to about 700 nm, and the light receiving wavelength region of the light receiving unit is λ nm, the light receiving wavelength region is only the range represented by the following equation: 0 <λ ≦ 700.

Such a biological information measuring device can constitute, for example, a pulse wave measuring device for displaying pulse wave information as biological information based on the detection result of the detecting means.

[0009]

In the pulse wave measuring device (biological information measuring device) according to the present invention, light is emitted from a light emitting portion such as an LED to a finger or a wrist, and reflected light from a blood vessel is detected by a light receiving portion such as a phototransistor. Thus, a change in blood volume caused by a pulse wave of blood is detected as a change in the amount of received light, and a pulse rate and a change in a pulse wave are displayed based on a pulse wave signal obtained thereby. In the present invention, the biological information is 300n
It is displayed based on the detection result in the wavelength region from m to 700 nm. In performing detection in such a wavelength range, for example, the wavelength range of the light emitting unit is at least 30
If the wavelength range is from 0 nm to 700 nm and the light receiving wavelength region is 700 nm or less, of the light included in the external light, the light having a wavelength region of 700 nm or less does not reach the light receiving portion using the finger as a light guide, Light in the wavelength region lower than 300 nm is almost absorbed on the skin surface. Therefore, the biological information can be measured from the detection result in the wavelength region from 300 nm to 700 nm based on only the light from the light emitting unit without being affected by external light. Therefore, unless external light is directly incident on the detection portion, erroneous detection of a pulse wave caused by external light does not occur, so that restrictions on use conditions can be relaxed without providing a large-scale light shielding structure.

Further, hemoglobin in blood has an absorption coefficient for light having a wavelength region in a range from 300 nm to 700 nm that is significantly larger than that for infrared light.

When light having a wavelength range from 300 nm to 700 nm is irradiated toward a living body in accordance with the light absorption characteristics of hemoglobin, the intensity of light reflected from the living body (blood vessel) changes with blood volume. It changes greatly following. Therefore, the S / N ratio of the pulse wave signal is improved.

[0012]

An embodiment of the present invention will be described with reference to the drawings.

(Overall Configuration) FIG. 1 is an explanatory view showing a use state of a pulse wave measuring apparatus according to an embodiment, and FIGS.
FIG. 3C is a cross-sectional view schematically illustrating a positional relationship between a finger on which the detection device of the pulse wave measurement device is mounted and the optical element, and FIG. 3 is an explanatory diagram illustrating an operation of the detection device mounted on the finger. .

In FIG. 1, a pulse wave measuring device 1 (biological information measuring device) of the present embodiment has a device main body 1 having a wristwatch structure.
0 and the cable 20 pulled out from the apparatus body 10
And a detection device 3 provided on the distal end side of the cable 20.
And a sensor fixing band 40 made of rubber or the like for mounting the detection device 30 on a finger or a wrist.

The main body 10 comprises a watch case 11 having a built-in timekeeping function, and a wristband 12 for attaching the watch case 11 to an arm. On the front side of the watch case 11, a liquid crystal display device 13 that displays, in addition to the current time and date, pulse wave information (biological information) based on the detection result of the detection device 30 and the like is configured. In addition, inside the watch case 11, in order to display a change in pulse rate or the like based on a detection result by the detection device 30,
A data processing circuit 50 for performing signal processing on the detection signal and the like is also built in, and the data processing circuit 50 and the liquid crystal display device 13 constitute a biological information display unit 60. Button switches 111 and 112 are provided on the outer surface of the watch case 11 for adjusting the time and switching the display mode.

The power source of the pulse wave measuring device 1 is a watch case 11
The cable 20 supplies power to the detection device 30 from the battery, and the detection device 3
The detection result of 0 is sent to the data processing circuit 50 in the watch case 11.
Can be entered.

In this example, the sensor fixing band 40 includes
A magic tape is stretched, and as shown by a solid line in FIG. 1, the sensor fixing band 40 can be attached in a state where the detection device 30 is in close contact with the base of the finger. Further, as shown by a dotted line in FIG. 1, the detection device 30 can be brought into close contact with a fingertip.

On the inner surface of the sensor fixing band 40, a detecting device 30 is fixed as a box-shaped optical unit 300, which is schematically shown in FIGS. 2 (a), 2 (b) and 2 (c). As described above, the LED 31 and the phototransistor 3
2 is pointed at the finger. Here, FIG. 2A shows a state in which the LED 31 and the phototransistor 32 are arranged in the length direction of the finger when the detection device 30 is attached in close contact with the base of the finger. FIG. 2B shows a state in which the detection device 30 is attached in a state in which the detection device 30 is in close contact with the fingertip.
LED 31 and phototransistor 3 in the length direction of the finger
2 shows a state where 2 are arranged. FIG. 2C shows a structure in which the LED 31 and the phototransistor 32 are arranged in the direction around the finger when the detection device 30 is attached to the finger in close contact with the finger.

In this example, as shown in FIG.
From the living body (blood vessel), and the light reflected from the living body (blood vessel) is received by the phototransistor 32 to detect a pulse wave from the living body (blood vessel).

In detecting such a pulse wave, in this example,
Biological information is displayed based on a detection result in a wavelength region from 300 nm to 700 nm instead of infrared light. That is, in the detection device 30, L whose emission wavelength region is in the range from 300 nm to 700 nm is used.
An ED 31 and a phototransistor 32 having a light receiving wavelength region of 700 nm or less are used, and biological information is displayed based on a detection result in a wavelength region from 300 nm to 700 nm which is an overlapping region. Such a detection device 3
When 0 is used, light having a wavelength region of 700 nm or less among the light included in the external light does not reach the phototransistor 32 (light receiving unit) using a finger as a light guide, while light having a wavelength of 300 nm or less is used as described later. Is almost absorbed at the skin surface.

Therefore, the detection result is 300 to 70 nm based on only the light of the light emitting portion without being affected by external light.
This is because biological information can be measured from a detection result in a wavelength region up to 0 nm.

Here, the light emitted from the LED 31 is:
A part of the light reaches the blood vessel through the finger as shown by the arrow C, and the reflected light from the hemoglobin in the blood reaches the phototransistor 32 as shown by the arrow D. The amount of light received on this path is the amount of biological reflection. A part of the light emitted from the LED 31 is reflected on the finger surface as shown by an arrow E and reaches the phototransistor 32. The amount of light received along this path is the amount of skin reflection. Furthermore, LED
As shown by arrows F and G, part of the light emitted from 31 and the light reflected from the blood vessels is absorbed or dispersed in the finger and does not reach the phototransistor 32.

In this example, the LED 31 is In
GaN-based (indium-gallium-nitrogen-based) blue LE
D is used, and the emission spectrum has an emission peak at 450 nm as shown in FIG. 4, and the emission wavelength range is from 350 nm to 600 nm. In this example, a GaAsP-based (gallium-arsenic-phosphorus-based) phototransistor is used as the phototransistor 32 corresponding to the LED 31 having such light emission characteristics, and the light receiving wavelength range of the element itself is shown in FIG. As shown, the main sensitivity region is in the range from 300 nm to 600 nm, and there is also a sensitivity region below 300 nm. Here, a sensor unit in which a filter is added to an element may be used as the phototransistor 32. An example of a light receiving wavelength region of such a sensor unit is, as shown in FIG. 6, a main sensitivity region from 400 nm to 550 nm. In the range. Since the power consumption of the LED 31 and the phototransistor 32 is relatively small, even when the timekeeping function and the pulse wave measurement function are driven by one small battery as in the pulse wave measurement device 1 of this example, the continuous operation time Is long.

(Structure of Detector) The structure of the optical unit will be described in detail with reference to FIGS. 7 is a plan view of the optical unit, FIG. 8 is a cross-sectional view taken along line AA 'of FIG. 7, FIG. 9 is a cross-sectional view taken along line BB' of FIG.
FIG. 8 is a sectional view taken along line CC ′ of FIG. 7.

In these figures, the optical unit 300
Then, the back cover 30 is attached to the sensor frame 301 as the case body.
2 is covered and the inside is a component storage space. The fixing of the back cover 302 to the sensor frame 301 is performed by three back cover fixing screws 303. The back cover fixing screw 303 is attached to the sensor fixing band 40 on the lower surface of the back cover 302.
Is fixed, and the sensor fixing band 40 is
It extends from 00 to both sides. The sensor frame 301 is oriented in a direction perpendicular to the sensor fixing band 40.
A cable 20 is drawn out from the inside of the cable. A glass plate 304 (filter) is provided on the upper surface of the sensor frame 301.
, A light transmission window is formed, and a circuit board 305 is fixed inside the sensor frame 301 so as to face the glass plate 304. On the circuit board 305, an LED 31, a phototransistor 32 (a sensor unit with a filter), and a transistor 309 are mounted.
The light-emitting surface and the light-receiving surface of the phototransistor 32 face the glass plate 304, respectively. The circuit board 305 is fixed to the sensor frame 301 by fixing the board set screw 307 to two pins 306 fitted from the upper surface of the sensor frame 301. The ground plate 308 is also fixed by the pins 306.

(Configuration of Data Processing Circuit) The configuration of the data processing circuit 50 provided inside the watch case 11 will be described with reference to FIG. FIG. 11 shows a data processing circuit 50.
FIG. 3 is a block diagram showing the configuration of FIG.

In the data processing circuit 50, the pulse wave signal converter 51 converts a signal input from the detector 30 via the cable 20 into a digital signal and outputs the digital signal to the pulse wave signal storage 52. I have. Pulse wave signal storage unit 52
Is a RAM for storing pulse wave data converted into digital signals. The pulse wave signal calculation unit 53 reads out the signal stored in the pulse wave signal storage unit 52, performs a frequency analysis on the signal, and inputs the result to the pulse wave component extraction unit 54. The pulse wave component extraction unit 54 extracts a pulse wave component from the input signal from the pulse wave signal calculation unit 53 and outputs it to the pulse rate calculation unit 55. The pulse rate calculation unit 55 determines the frequency of the input pulse wave. The pulse rate is calculated based on the components, and the result is output to the liquid crystal display device 13.

(Operation) The operation of the pulse wave measuring apparatus 1 thus configured will be briefly described with reference to FIGS. 1, 3 and 11. First, as shown in FIG. 1, the device main body 10 is worn on the arm with the wrist band 12, and the detection device 30 (the glass plate 304 of the optical unit 300) is brought into close contact with the finger by the sensor fixing band 40. In this state, as shown schematically in FIG. 3, when light is emitted from the LED 31 toward the finger, this light reaches the blood vessel and is partially absorbed by hemoglobin in the blood and partially reflected. Living body (blood vessels)
Is reflected by the phototransistor 32, and a change in the amount of received light corresponds to a change in blood volume caused by a pulse wave of blood. That is, when the blood volume is large, the reflected light is weak, while when the blood volume is small, the reflected light is strong. Therefore, if the change in the reflected light intensity is monitored by the phototransistor 32, the pulse and the like can be detected. In order to perform such detection, the data processing circuit 50 shown in FIG.
Then, a signal input from the phototransistor 32 (detection device 30) is converted into a digital signal, and the digital signal is subjected to frequency analysis and the like to calculate a pulse rate. Then, the pulse rate obtained by the calculation is displayed on the liquid crystal display device 13. That is, the pulse wave measuring device 1 functions as a pulse meter.

(Effects of Embodiment) In this embodiment, the emission wavelength range of the LED 31 is in the range of 350 nm to 600 nm, and the light reception wavelength range of the phototransistor 32 is in the range of the main sensitivity range of 300 nm to 600 nm. . The light receiving wavelength range when a unit combining an element and a filter is used as the phototransistor 32 is in a range from 400 nm to 550 nm.
Therefore, even if the pulse wave is measured in the simple light-shielded state shown in FIG. 1, among the light contained in the external light, the light having a wavelength region of 700 nm or less uses the finger as a light guide and the phototransistor 32.
Since only light in the wavelength region that does not reach the (light receiving portion) and does not affect detection passes through the finger as a light guide, in this example, external light hits the exposed portion of the finger. However, the external light does not affect the detection result of the pulse wave. In this example, the S / N ratio of the pulse wave signal based on the change in blood volume is high. The reason will be described below.

First, the reason for being hardly affected by external light will be described with reference to FIG. FIG. 12A shows the relationship between the wavelength of light and the light transmittance of the skin. Here, the polygonal line a is a transmission characteristic for light having a wavelength of 200 nm, the polygonal line b is a transmission characteristic for light having a wavelength of 300 nm, the polygonal line c is a transmission characteristic for light having a wavelength of 500 nm, and the polygonal line d is a transmission characteristic for light having a wavelength of 700 nm. The transmission characteristic of light and the broken line e indicate the transmission characteristic of light having a wavelength of 1 μm. As is clear from this figure, among the light included in the external light, light having a wavelength region of 700 nm or less tends to be hard to transmit through the finger, and thus the external light is not covered with the sensor fixing band 40. In FIG. 3, a dotted line X
As shown in the figure, the light does not reach the phototransistor 32 through the finger. Therefore, if light of 700 nm or less is used as detection light as in this example, the influence of external light can be suppressed by covering only the minimum necessary range without covering the finger in a large scale. The example pulse wave measuring device 1 can be used outdoors. In addition, since light in a wavelength region lower than 300 nm is almost absorbed by the skin surface, even if the light receiving wavelength region is set to 700 nm or less, the substantial light receiving wavelength region is:
It becomes 300 nm to 700 nm.

On the other hand, when an LED having an emission peak near 880 nm is used and a silicon-based phototransistor is used as in the prior art, the light receiving wavelength range is from 350 nm to 1200 nm as shown in FIG. Range. Therefore, in the conventional optical system (detection device),
Of the external light, as shown by an arrow Y in FIG. 3, light having a wavelength of 1 μm that easily reaches the light receiving portion using a finger as a light guide, that is, light shown by a polygonal line e in FIG. Since the pulse wave is detected based on the detection result, erroneous detection due to a change in external light is likely to occur.

Next, the reason why the S / N ratio of the pulse wave signal is high in the pulse wave measuring apparatus 1 of the present embodiment will be described with reference to FIG. FIG. 12B is an explanatory diagram showing the relationship between the wavelength of light and the light absorption characteristics of various hemoglobins.

FIG. 12 (b) shows the light absorption characteristics of hemoglobin not bound to oxygen by a curve Hb, and the light absorption characteristics of hemoglobin bound to oxygen by a curve HbO2. As shown by these curves, hemoglobin in blood has a large extinction coefficient for light having a wavelength of 300 nm to 700 nm, and a wavelength of 88 μm, which is conventional detection light.
It is several times to about 100 times or more larger than the extinction coefficient for light of 0 nm. Therefore, as in this example, the wavelength region (300
When light of (nm to 700 nm) is used as the detection light, the detection value changes with high sensitivity to a change in blood volume, so that a pulse wave detection rate (S / N ratio) based on the change in blood volume is high.

(Amount of External Light Penetrating Under Each Light-Shielding Condition) In evaluating the pulse wave measuring apparatus 1 of this embodiment, FIGS.
As shown in (e), while changing the light shielding range for the finger from condition 1 to condition 5, only the amount of penetration of external light was measured in comparison with a conventional pulse wave measurement device (comparative example). Here, as the pulse wave measuring device 1 of this example, the light receiving sensitivity is from 400 nm to 6 nm.
Sample 1 using a 00 nm phototransistor 32;
Sample 2 using a phototransistor 32 having a light receiving sensitivity of 300 nm to 700 nm was used for evaluation. On the other hand, as comparative examples, samples 3, 4, and 5 whose light receiving sensitivity deviated from the range from 300 nm to 700 nm were used for evaluation. The condition 1 is a condition in which the base of the index finger is covered with a light-shielding cover with a width of 10 mm as shown in FIG.
FIG. 14B shows a state in which the base of the index finger is covered with a light-shielding cover with a width of 20 mm as shown in FIG.
(C) As shown in FIG.
As shown in FIG. 14 (d), a state where the base of the forefinger is covered with a light-shielding cover with a width of 70 mm as shown in FIG. 14 (d), and condition 5 is as shown in FIG. 14 (e). ,
The entire index finger, the base of the thumb, the base of the middle finger, and the vicinity of the base of each finger are covered with a light-shielding cover.

Table 1 shows the measurement results of the amount of external light penetrating under each of these conditions. The penetration amount of external light is represented by the output current of the phototransistor (unit: μA).

[0036]

[Table 1]

As shown in Table 1, the pulse wave measuring device 1 of this embodiment
According to (Samples 1 and 2), since light in the wavelength region from 300 nm to 700 nm is received, the influence of external light can be ignored under any of the conditions performed this time. Of the light included in the external light, light having a wavelength region of 700 nm or less
This is because the finger does not reach the phototransistor 32 (light receiving portion) as a light guide. Therefore, according to the pulse wave measuring device 1 of the present embodiment, it is sufficient that the finger is covered with the width of 10 mm by the detecting device 30 itself or the sensor fixing band 40 (light shielding cover). On the other hand, in the pulse wave measurement device (samples 3, 4, and 5) of the comparative example, the whole of the index finger, the base of the thumb, the base of the middle finger, and the vicinity of the base of each finger were covered over a wide range (condition 5). ), The effect of external light can be ignored, and a large-scale light shielding structure is required.

(Effects of External Light in Each Environment) In this example, an LED 31 (blue light source) having an emission wavelength peak of 450 nm was used, and a GaAsP phototransistor 32 having a light reception wavelength range of 300 nm to 600 nm was used. Pulse wave measuring device 1 and LE having an emission wavelength peak of 880 nm
D, the light receiving wavelength range is from 350 nm to 1200 nm
FIG. 15 and FIG. 16 show the results of comparing and examining the degree of the influence of external light with respect to the pulse wave measuring device using the phototransistor up to (comparative example). The data shown in the figure shows the result of performing frequency analysis on the detection result of the pulse wave, and the peak with an arrow among many peaks corresponds to the frequency of the pulse wave.

FIG. 15A shows a result of measurement of a pulse wave when the vehicle travels in a dark room environment with the pulse wave measuring device of the present example being worn on an arm. FIG. 15 (b) shows a measurement result of a pulse wave when the vehicle travels in one direction toward sunlight with the pulse wave measurement device of the present example being worn on an arm. FIG.
(C) shows a state in which the pulse wave measuring device of this example is worn on the arm,
The measurement result of the pulse wave when the vehicle travels while turning so that the relative direction of the sunlight fluctuates is shown. Under any of the conditions shown in these figures, the peak of the pulse wave with an arrow is clearer than the other peaks, and the pulse wave measurement device 1 of the present example is hardly affected by external light. I understand.

FIG. 16A shows a result of measurement of a pulse wave when the vehicle travels in a dark room environment while the conventional pulse wave measuring device is worn on the arm. FIG. 16 (b) shows a measurement result of the pulse wave when the pulse wave measurement device of the present example is worn on the wrist and travels in one direction toward sunlight. FIG.
(C) shows a state in which the pulse wave measuring device of this example is worn on the arm,
The measurement result of the pulse wave when the vehicle travels while turning so that the relative direction of the sunlight fluctuates is shown. As shown in these figures, the conventional pulse wave measurement device can measure a pulse wave only in a dark room environment, and under conditions where external light is applied,
It turns out that measurement is impossible.

(Relative Sensitivity of Pulse Wave Signal) Next, the pulse wave signal level (μA) when the pulse wave is measured by the pulse wave measuring device 1 of the present embodiment and the conventional pulse wave measuring device (comparative example). ,
Table 2 shows the results of comparing and examining the overall level (μA) of the reflected light and the ratio of the pulse wave signal included in the reflected light. Here, as the pulse wave measuring device 1 of the present example, the emission wavelength range is 420 n.
In addition to the sample 6 using the LED 31 (blue emission color) of m to 480 nm, the emission wavelength range is 540 to 57 nm.
Sample 7 using 0 nm LED 31 (green emission color) was also provided for evaluation.

In Sample 7, a GaP-based LED 31 having a green emission color was used.
As shown in FIG. 17, D31 has a main light emission region in the range of 540 nm to 570 nm as shown in FIG. 17, and the light emission region extends from 520 nm to 600 nm. In the sample 7 using such a GaP-based LED 31, a GaP-based phototransistor 32 is used in accordance with its light-emitting characteristics.
As shown in the figure, the sensitivity region is in the range from 200 nm to nearly 700 nm.

As a comparative example, the emission wavelength range was 3
Sample 8, which deviated from the range of 00 nm to 700 nm,
9 and 10 were evaluated.

Table 2 shows the evaluation results.

[0045]

[Table 2]

As shown in Table 2, the pulse wave measuring device 1 of this embodiment
According to (Samples 6 and 7), the emission wavelength range is 30 in accordance with the wavelength range where the absorption coefficient of hemoglobin in blood is large.
Since a certain light in the range from 0 nm to 700 nm is used, the ratio of the pulse wave signal included in the reflected light is 0.019,
It is as large as 0.013 and has high sensitivity. On the other hand, in the pulse wave measuring devices (samples 8, 9, and 10) of the comparative example, the ratio of the pulse wave signal included in the reflected light is very small, 0.002 or less, and the sensitivity is low. That is, the sensitivity of the pulse wave measuring device 1 of the present example is about 10 times smaller than the conventional one in the S / N ratio of the pulse wave signal.
Improve dramatically by nearly double.

(Effect of Skin Color) Next, Table 3 shows the result of an examination that the advantage of the high sensitivity of the pulse wave measuring device 1 of the present embodiment is not affected by the skin color. In this evaluation, the pulse wave measuring device 1 of this example using an LED (blue light source) having an emission wavelength peak of 450 nm that is hardly reflected on the surface of the skin
(Sample 11) and 880 nm that easily reflects on the surface of the skin
With respect to a conventional pulse wave measuring device using LED having an emission wavelength peak of Comparative Example (Comparative Example, Sample 12), pulse waves of yellow race, white and black were measured, and the amount of skin reflection detected at that time was measured. , The amount of biological reflection (the amount of reflection from blood vessels), and the pulse wave component were calculated.

[0048]

[Table 3]

As a result, as shown in Table 3, yellow race,
It was demonstrated that the ratio of the pulse wave component to the total amount of received light was high, that is, the measurement sensitivity to the biological information was high, regardless of whether the race was white or black.

(Other Examples) As shown in FIG. 12 (b), the light absorption characteristics of hemoglobin in blood differ between hemoglobin not bound to oxygen and hemoglobin bound to oxygen. Different from 300nm to 700n
When light having a wavelength of up to m, for example, light having a wavelength of about 470 nm is used as detection light, the amount of various hemoglobins, the total amount of hemoglobin, and the like can be measured as biological information from the intensity. In addition, for example, the moisture contained in the skin can be measured as biological information from the difference in the light absorption characteristics between the skin and the moisture.

[0051]

As described above, in the pulse wave measuring apparatus (biological information measuring apparatus) according to the present invention, light is emitted from a light emitting portion such as an LED to a fingertip or the like, and reflected light from blood or the like is reflected by a phototransistor. And the like, and the biological information is measured based on the detection result in the wavelength region from 300 nm to 700 nm of the detecting means. In performing detection in such a wavelength region, for example, if the wavelength region of the light emitting unit is at least in a range from 300 nm to 700 nm and the light receiving wavelength region is 700 nm or less, the wavelength region of the light included in the external light is 700 nm. The following light does not reach the light receiving portion using the finger as a light guide, while light in a wavelength region lower than 300 nm is almost absorbed by the skin surface. Therefore, the biological information can be measured from the detection result in the wavelength region from 300 nm to 700 nm based on only the light from the light emitting unit without being affected by external light.
Therefore, unless external light is directly incident on the detection portion, erroneous detection of a pulse wave caused by external light does not occur, so that restrictions on use conditions can be relaxed without providing a large-scale light shielding structure.

Further, hemoglobin in blood has an absorption coefficient for light having a wavelength region in the range of 300 nm to 700 nm that is significantly larger than that for infrared light.

When light having a wavelength range from 300 nm to 700 nm is irradiated toward a living body in accordance with the absorption characteristics of hemoglobin, the intensity of light reflected from the living body (blood vessel) changes with the blood volume. It changes greatly following. Therefore, since the S / N ratio of the pulse wave signal is improved, the pulse wave measurement device according to the present invention also has an effect that the measurement sensitivity of the pulse wave is high.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a use state of a pulse wave measuring device according to one embodiment of the present invention.

FIGS. 2A to 2C are cross-sectional views schematically showing a positional relationship between a detection device and a finger in the pulse wave measurement device shown in FIG.

FIG. 3 is an explanatory diagram showing an operation of a detection device attached to a finger in the pulse wave measurement device shown in FIG.

FIG. 4 is an explanatory diagram showing an emission spectrum of an InGaN blue LED used in the pulse wave measuring device shown in FIG.

FIG. 5 is an explanatory diagram showing light receiving characteristics of an InGaP-based phototransistor used in the pulse wave measuring device shown in FIG.

FIG. 6 is an explanatory diagram showing light receiving characteristics of a phototransistor unit with a filter used in the pulse wave measuring device shown in FIG.

FIG. 7 is a plan view showing a configuration of a detection device (optical unit) of the pulse wave measurement device shown in FIG.

FIG. 8 is a sectional view taken along line AA ′ of FIG. 7;

FIG. 9 is a sectional view taken along line BB ′ of FIG. 7;

FIG. 10 is a sectional view taken along line CC ′ of FIG. 7;

11 is a block diagram showing a configuration of a data processing circuit of the pulse wave measuring device shown in FIG.

12A is a graph showing the relationship between the wavelength of light and the light transmittance of the skin, and FIG. 12B is an explanatory diagram showing the relationship between the wavelength of light and the light absorption characteristics of various hemoglobins. .

FIG. 13 is an explanatory diagram showing light receiving characteristics of a silicon-based phototransistor used in a conventional pulse wave measuring device.

FIG. 14 is an explanatory diagram showing various experimental conditions in which a light shielding range to a finger is changed in evaluating a degree of intrusion of external light in the pulse wave measuring device of the present example.

FIG. 15 is an explanatory diagram showing data obtained by performing frequency analysis on a result of detection of a pulse wave by the pulse wave measurement device of the present example when evaluating the influence of external light in the pulse wave measurement device of the present example.

FIG. 16 is an explanatory diagram showing data obtained by performing frequency analysis on a result of detection of a pulse wave by the pulse wave measurement device according to the comparative example in evaluating the influence of external light in the pulse wave measurement device of the present example.

17 is an explanatory diagram showing an emission spectrum of a GaP-based LED used in the pulse wave measuring device shown in FIG.

FIG. 18 shows GaAsP used in the pulse wave measuring device shown in FIG.
FIG. 4 is an explanatory diagram showing light receiving characteristics of a system phototransistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pulse wave measuring device (biological information measuring device) 10 ... Device main body 11 ... Watch case 12 ... Wristband 13 ... Liquid crystal display device 20 ... Cable 30 ... Detector 31 ... LED (light emitting part) 32 ... phototransistor (light receiving part) 40, 40A ... Sensor fixing band 50 ... Data processing circuit 51 ... Pulse wave signal converter 52 ... Pulse Wave signal storage unit 53 pulse wave signal calculation unit 54 pulse wave component extraction unit 55 pulse rate calculation unit 60 biological information display means 300 optical unit 301 sensor frame 305: circuit board 304: glass plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuyuki Honda 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (72) Inventor Masayuki Kawada 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments, Inc.

Claims (3)

[Claims] 1. A light emitting unit for irradiating a part of a living body with light, a detecting unit including a light receiving unit for receiving light emitted from the light emitting unit through the living body, and a detecting unit based on a detection result of the detecting unit. A biological information display device for displaying biological information by displaying the biological information based on a detection result in a wavelength region from about 300 nm to about 700 nm of the detection means. Biological information measuring device. 2. The light-receiving wavelength region according to claim 1, wherein a light-emitting wavelength region of the light-emitting unit is at least in a range from about 300 nm to about 700 nm, and a light-receiving wavelength region of the light-receiving unit is λ nm. The biological information measuring device is only in a range that satisfies the formula 0 <λ ≦ 700. 3. A pulse wave measuring device comprising the biological information measuring device defined in claim 1 or 2, wherein the pulse wave information as the biological information is displayed based on a detection result of the detecting means. Pulse wave measuring device.