JPH11128177A - Bio-information detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect bio-information without making contact with the living body even if the living body is moving. SOLUTION: A P-polarized beam is irradiated toward a living body 10 by a polarization filter 16 and a lens 18, and the beam reflected from the living body 10 is split by a polarization beam splitter 22 into a P-polarized beam and an S-polarized beam, which are detected respectively by a first light receiving part 24 and a second light receiving part 26. A processing circuit 28 multiplies detection data about the S-polarized beam by K so that the component of movement of the living body involved in the detection data about the P- polarized beam and the S-polarized beam detected by the first light receiving part 24 and the second light receiving part 26 become equal. The difference between the detection data about the S-polarized beam multiplied by K and the detection data about the P-polarized beam is computed to obtain information about the heartbeats of the living body.

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 detecting apparatus, and more particularly, to a living body information detecting apparatus that irradiates an area where a living body is movably arranged with light to detect living body information.

[0002]

2. Description of the Related Art Conventionally, a heart rate measuring device has been proposed as a biological information detecting device. The heart rate measuring device irradiates the skin with light, detects reflected light or transmitted light, and measures the heart rate (heart beat). Hereinafter, this principle will be described.

[0003] With the movement of the heart, the amount of blood existing near the skin surface inside the skin increases and decreases. On the other hand, the light applied to the skin separates into light reflected on the skin surface and light entering the skin. The light that enters the skin,
Furthermore, it is separated into one that is absorbed by blood existing near the skin surface inside the skin and one that is diffused inside the skin and reflected outside the skin surface. The amount of light absorbed by the blood changes according to the change in the amount of blood, that is, the heartbeat. Therefore,
The amount of light reflected from the inside of the skin changes according to the heartbeat. Therefore, the heart rate can be measured from the heart rate component of the light reflected from the inside of the skin.

Meanwhile, a heart rate measuring device includes a contact type (pulse oximeter) for bringing a measuring part into contact with a part (a finger or the like) of a living body and a non-contact type (patent application Hei 10) for measuring a heart rate without contacting the living body. 8-73663).

[0005] The contact type heart rate measuring device is a device in which a light source, a finger, and a measuring section which comes into contact with the finger are arranged in order, and the transmitted light from the finger is measured by the measuring section to measure the heart rate. In the contact heart rate measurement device, since the finger and the measurement unit are in contact with each other, a change in the amount of transmitted light due to movement, vibration, or the like of the finger is small.

[0006] The non-contact type heart rate measuring device has two types of LEDs.
Light from a light source and a light source is transmitted through two types of interference filters to irradiate the skin with first light having a high transmittance to the inside of the skin and second light having a high reflectance on the skin surface. Since the first light has a high transmittance to the inside of the skin, it passes through the inside of the skin, and the reflected light from the inside of the skin contains a large amount of heartbeat components. In addition, the second light has a high reflectance on the skin surface, so that it is reflected from the skin surface, and the reflected light does not contain much heartbeat components. And
Since each reflected light has noise due to the movement of the living body, each reflected light is combined and the noise is removed to measure the heart rate.

[0007]

However, in the contact type heart rate measuring device, since the finger and the measuring unit are in contact with each other, the contact type heart rate measuring device restrains the living body, hinders free movement, and causes annoyance.

On the other hand, in the non-contact type heart rate measuring device, the above problem does not occur because the living body and the measuring unit are not in contact with each other.
When the living body moves freely, the detection amount of the reflected light changes.
The heartbeat component is weak and has a small proportion in the total amount of reflected light. Therefore, when the living body moves freely, the heartbeat component is buried in the change in the amount of reflected light, and it becomes difficult to detect the heartbeat. When two types of light are used, two types of LEDs or two interference filters are used.
Light sources corresponding to wavelengths, such as separation into different types of light, must be prepared, which increases costs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and proposes a biological information detecting device which is non-contact type with respect to a living body and which can accurately detect information of the living body even when the living body moves. With the goal.

[0010]

To achieve the above object, the present invention provides an irradiating means for irradiating a living body with linearly polarized light,
The reflected light reflected from the living body is converted into a first linearly polarized light in which the vibration direction of the electric vector is the same as the electric vector of the linearly polarized light and a second vibrational direction in which the vibration direction of the electric vector is perpendicular to the electric vector of the linearly polarized light. Separation means for separating the first linearly polarized light and the second linearly polarized light separated by the separation means,
At least one of the first linearly polarized light and the second linearly polarized light so that the difference between the moving components of the living body in the detection data of the first linearly polarized light and the second linearly polarized light detected by the detecting means is reduced. One of the detection data is processed to calculate data corresponding to the detection data of each of the first linearly polarized light and the second linearly polarized light, and a difference or quotient of the calculated data is calculated to obtain biological information. Means.

The irradiating means irradiates the living body with linearly polarized light. When irradiated with linearly polarized light, it is reflected from the living body.
The reflected light includes surface reflected light that is reflected from the surface of the living body without being diffused, surface diffused reflected light that is diffusely reflected from the surface of the living body, and intra-layer diffuse reflected light that is diffusely reflected inside the living body (in the layer). , There is. Here, it is generally known that the polarization state changes when light is reflected, and the change is different between the surface diffuse reflected light and the surface diffuse reflected light and the layer diffuse reflected light. That is, the surface reflected light is the first linearly polarized light in which the vibration direction of the electric vector is the same as the linearly polarized light, and includes only the moving component of the living body. The surface reflected light and the intra-layer diffuse reflected light include a first linearly polarized light and a second linearly polarized light whose electric vector oscillates in a direction perpendicular to the linearly polarized light. The linearly polarized light includes a moving component of the living body and an information component of the living body.

[0012] The separating means reflects the reflected light from the living body,
The light is separated into first linearly polarized light and second linearly polarized light. The detecting means detects the first linearly polarized light and the second linearly polarized light separated by the separating means.

The calculating means includes a first linearly polarized light and a second linearly polarized light so as to reduce a difference between moving components of the living body in the detected data of the first linearly polarized light and the second linearly polarized light detected by the detecting means. At least one of the detection data of the polarized light is processed to calculate data corresponding to the detection data of each of the first linearly polarized light and the second linearly polarized light, and a difference or a quotient of the calculated data is calculated to obtain biological information. .

As described above, the living body is irradiated with the linearly polarized light, and the reflected light reflected from the living body is combined with the first linearly polarized light and the second linearly polarized light.
And at least one of the first linearly polarized light and the second linearly polarized light so that the difference between the moving components of the living body in the detection data of the first linearly polarized light and the second linearly polarized light becomes smaller. Since the detection data is processed, the difference between the information components of the living body in the data corresponding to the detection data of each of the first linearly polarized light and the second linearly polarized light increases.

Therefore, if the difference or the quotient of the data corresponding to the detection data of each of the first linearly polarized light and the second linearly polarized light is calculated, information on the living body can be accurately calculated even if the living body moves. .

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, the biological information detecting device according to the present embodiment includes a light emitting unit 12 and a drive circuit 14 for driving the light emitting unit 12. In addition, the biological information detection device is configured to move in a direction in which the light emitted from the light emitting unit 12 travels.
A polarizing filter 16 that converts light emitted from the light emitting unit 12 into linearly polarized light (P-polarized light), and a first light receiving unit 24 and a second light receiving unit 26 that convert the linearly polarized light from the polarizing filter 16 into a later-described one.
A lens 18 (focal length 30 [mm]),
Are arranged in order. Note that the light emitting unit, the polarizing filter 16 and the lens 18 constitute an irradiation unit of the present invention.

The distance between the light emitting section 12 and the lens 18 is L1 (for example, 130 [mm]). Also,
L2 (for example, 40 [m
m]) The distant position is the measurement area 20.

The measurement area 20 of the object to be measured (living body) 10
In the direction in which light is reflected from the surface located at
At a position separated by a predetermined distance from 0, the light reflected from the surface of the measured object 10 is perpendicular to the first linearly polarized light (P-polarized light) in which the oscillation direction of the electric vector is the same as the linearly polarized light by the polarizing filter 16. Polarizing beam splitter 2 as a separating means for separating light into second linearly polarized light (S-polarized light)
2 are arranged.

In the direction in which the first linearly polarized light (P-polarized light) separated by the polarization beam splitter 22 travels,
A first light receiving unit 24 that receives linearly polarized light (P-polarized light) is disposed. In the direction in which the second linearly polarized light (S-polarized light) separated by the polarization beam splitter 22 travels, a second light receiving unit 26 that receives the second linearly polarized light (S-polarized light) is arranged. Note that the distance between the measurement area 20 and each of the first light receiving unit 24 and the second light receiving unit 26 is L3 (for example, 160 [mm]). The first light receiving unit 24
The second light receiving section 26 constitutes the detecting means of the present invention.

The first light receiving section 24 and the second light receiving section 26
Is connected to a processing circuit 28 as an arithmetic means of the present invention, and the processing circuit 28 is connected to a data analysis system 30.

As shown in FIG. 2A, the light emitting section 12
An LED 32 that emits light having an emission wavelength of 870 [nm]
In the center, P1 (for example, 8
[Mm]) Four are arranged at a pitch interval, three are arranged at a pitch P3 (for example, 22 [mm]) in the vertical direction A across the center, and three are arranged at a P3 pitch interval horizontally across the center. One is arranged and configured.

As the polarizing filter 16, a film polarizing plate (manufactured by POLAROID) having sufficient polarization characteristics at the wavelength (870 [nm]) of light from the light emitting section 12 is used.

As shown in FIG. 2B, the first light receiving section 2
Reference numeral 4 includes a Si photodiode 34 and a C-mount lens (focal length 16 [mm]) 36.

Next, the operation of the present embodiment will be described. As shown in FIG. 3, the linearly polarized light I _P
Is condensed and radiated onto the measured object 10 located in the measurement area 20 via the lens 18. When linearly polarized light I _P to be measured 10 is irradiated, it is reflected from the measurement object 10.

The light reflected from the measured object 10 is separated into P-polarized light and S-polarized light by the polarization beam splitter 22. The P-polarized light is received by the first light receiving unit 24,
The S-polarized light is received by the second light receiving unit 26.

The received light data (P-polarized light component H _PP ) by the first light receiving unit 24 and the received light data (S-polarized light component H _Ps ) by the second light receiving unit 26 are input to the processing circuit 28.

The heartbeat information calculation processing routine (see FIG. 4) executed by the processing circuit 28 when a start button (not shown) is turned on will be described.

When this routine starts, step 42 is executed.
In step 44, the first linearly polarized light (P-polarized light component H _PP ) received by the first light receiving unit 24 is fetched.
The second linearly polarized light (S-polarized light component _HPs ) received by the light receiving unit 26 is taken in.

In step 46, the heart rate information D is calculated based on the equation (1).

[0031]

## EQU1 ## D ← H _pp −K * H _ps (1) Equation (1) will be described below.

The reflected light reflected from the measured object 10 includes:
As shown in FIG. 3, the surface reflected light S _PP that is reflected from the surface of the measured object 10 without being diffused, the surface diffuse reflected light SD _PP and SD _{PS that} is diffusely reflected from the surface of the measured object 10, and the measured light There are in-layer diffuse reflection light ID _PP and ID _PS that diffusely reflect inside the object 10 (inside the layer). Here, _PP represents a P-polarized light component, and _PS represents an S-polarized light component.

Here, the surface reflected light Sp is linearly polarized light I _P
There is a property of being reflected while maintaining the polarization state corresponding to (P-polarized light) (property having a P-polarized component), and is expressed by equation (2). The surface diffuse reflection light SD _PP and the intra-layer diffuse reflection light ID _PP have the property that the polarization characteristics become random (P
(A property having a polarized light component and an S-polarized light component), and are represented by the equations (3) and (4), respectively.

[0034]

## EQU2 ## Surface reflected light Sp = S _pp (2)

[0035]

[Expression 3] Surface diffuse reflection light SDp = SD _pp + SD _ps (3)

[0036]

## EQU4 ## Diffuse reflected light in the layer IDp = ID _pp + ID _ps (4) Further, the surface reflected light Sp has only the movement component of the surface of the measured object 10 and is expressed by the equation (5). You. The surface diffuse reflected light SD _PP and the intra-layer diffuse reflected light ID _PP have a motion component and a heartbeat component, and are represented by equations (6) and (7), respectively. However, the motion component is represented by _(m), and the heartbeat component is represented by _(s) .

[0037]

## EQU5 ## Surface reflected light Sp = S _{pp (m)} (5)

[0038]

[6] surface diffusion reflection light _{SDp = SD pp (s) +} SD pp (m) + SD ps (s) + SD ps (m) ··· (6)

[0039]

## EQU00007 ## Diffuse reflected light in the layer IDp = ID.sub.pp _(s) + _{ID.sub.pp (m)} + _{ID.sub.ps (s)} + _{ID.sub.ps (m)} (7) And, the equations (5) to (7) are Decomposed into a polarized light component H _pp and an S polarized light component H _ps and put together, (8)
Expression (9) The P-polarized light component H _pp is received by the first light receiving unit 24, and the S-polarized light component H _ps is received by the second light receiving unit 26.

[0040]

## EQU8 ## P polarization component H _pp = S _{pp (m)} + SD _{pp (s)} + SD _{pp (m)} + ID _{pp (s)} + ID _{pp (m)} (8)

[0041]

S p _-polarized light component H _ps = SD _{ps (s)} + SD _{ps (m)} + ID _{ps (s)} + ID _{ps (m)} (9) where the motion component of the P-polarized light component and the S-polarized light component The S-polarized component H _ps indicated by reference numeral 50 in FIG. 5A is set so that the difference from the motion component is reduced, for example, to be equal.
Is multiplied by K. This makes it possible to increase the difference between the heart rate component of the P-polarized component and the heart rate component of the S-polarized component. Note that the value of K is obtained by equation (10).

[0042]

(Equation 10)

The light intensity (light amount per unit time) of the linearly polarized light I _P irradiating the object to be measured 10 is known in advance.
_{pp (m)} , SD _{pp (m)} , ID _{pp (m)} , SD _{ps (m)} , and I
The value of _{Dps (m)} can be estimated. Therefore, the value of K can also be determined in advance.

The difference between the P-polarized light component indicated by reference numeral 54 in FIG. 5B and the S-polarized light component multiplied by K indicated by reference numeral 52 in FIG. 5A is given by equation (11).

[0045]

H _pp −K * H _ps = S _{pp (m)} + SD _{pp (s)} + SD _{pp (m)} + ID _{pp (s)} + ID _{pp (m)} −K * (SD _{ps (s)} + SD _{ps (m )} + ID _{ps (s)} + ID _{ps (m)} ) = S _{pp (m)} + SD _{pp (m)} + ID _{pp (m)} -K * SD _{ps (m)} -K * ID _{ps (m)} + SD _{pp (s)} + ID _{pp (s)} -K * SD _{ps (s)} -K * ID _{ps (s)} (11) As described above, in order to make the motion component of the P-polarized component equal to the motion component of the S-polarized component. Since the S-polarized component H _ps is multiplied by K (see equation (10)), S _{pp (m)} + SD _{pp (m)} + ID _{pp (m)} −K * SD _{ps (m)} −
K * ID _{ps (m)} = 0. Therefore, equation (11) can be transformed into equation (12).

[0046]

H _pp −K * H _ps = SD _{pp (s)} + ID _{pp (s)} −K * SD _{ps (s)} −K * ID _{ps (s)} (12) By making the motion component of the polarization component equal to the motion component of the S polarization component and performing the difference processing, FIG.
As shown in (C), only the heart rate information D can be extracted.

In step 48, the heart rate information D is output to the data analysis system 30 by multiplying it by a predetermined number (for example, 10,000 times).

The data analysis system 30 creates a heart rate graph based on the heart rate information D as shown in FIG.
Display on the display.

The heart rate graph shown in FIG. 6 is for the subject A, but the heart rate was similarly detected for the subjects B and C. The heart rate was confirmed with a commercially available heart rate monitor.

As described above, the object to be measured is irradiated with the P-polarized light, and the light reflected from the object to be measured is reflected by the P-polarized light and the S-polarized light.
The light is separated into polarized light, the motion component of the P-polarized component is made equal to the motion component of the S-polarized component, and the difference processing is performed to detect only the heartbeat information.

Therefore, even if the object to be measured moves, FIG.
As shown in FIGS. 5A to 5C, the motion component 58 is canceled, so that the heartbeat information can be detected with high accuracy.

In the embodiment described above, the S-polarized component is multiplied by K in order to make the motion component of the P-polarized component equal to the motion component of the S-polarized component. However, the present invention is not limited to this. The P-polarized component may be multiplied by 1 / K, and the S-polarized component and the P-polarized component may be processed so that the motion component of the P-polarized component and the motion component of the S-polarized component become equal. Note that the motion component of the P-polarized component and the motion component of the S-polarized component are not limited to being equal, and the difference between the motion component of the P-polarized component and the motion component of the S-polarized component is reduced. The P-polarized component and the S-polarized component may be processed such that the difference between the heartbeat component of S and the heartbeat component of the S-polarized component increases.

In the above-described embodiment, at least one of the P-polarized light component and the S-polarized light component is processed as described above to calculate the difference. However, the present invention is not limited to this. The quotient may be calculated by processing at least one of the polarization components as described above.

In the above-described embodiment, the heart rate is obtained. However, the present invention is not limited to this, and the blood pressure may be obtained based on the heart rate information.

In the above-described embodiment, the polarization beam splitter, the first light receiving unit, and the second light receiving unit are provided. However, the present invention is not limited to this, and the polarization beam splitter, the first light receiving unit, and the like are not limited thereto. , And the second light receiving unit may be omitted, and a polarizing filter and a light receiving unit may be provided.
When detecting the P-polarized light component, the polarization filter is set to have the same direction as the polarization filter 16 on the light source side. That is, only the P-polarized light is transmitted by the polarizing filter. When detecting the S-polarized component, the polarization filter is connected to the polarization filter 16 on the light source side by 90 °. That is, only the S-polarized light is transmitted by the polarizing filter.

In the above embodiment, the object to be measured is irradiated with P-polarized light. However, the present invention is not limited to this.
The object to be measured may be irradiated with polarized light.

In the above-described embodiment, the light emitting portion is L
Although the ED is used, the present invention is not limited to this, and a light bulb such as a tungsten lamp or a halogen lamp may be used.
A wavelength may be selected by adding a filter to these.

In the above-described embodiment, a film polarizing plate is used, but the present invention is not limited to this, and a glass polarizing plate may be used.

[0059]

As described above, according to the present invention, the reflected light from the living body is separated into the first linearly polarized light and the second linearly polarized light, and the living body in each of the first linearly polarized light and the second linearly polarized light is separated. The detection data of at least one of the first linearly polarized light and the second linearly polarized light is processed so that the difference between the moving components of the first linearly polarized light and the second linearly polarized light becomes smaller. Has the effect that the information of the living body can be accurately calculated even if the living body moves.

[Brief description of the drawings]

FIG. 1 is a block diagram of a biological information detection device according to the present embodiment.

FIG. 2A is a diagram illustrating a state of a light emitting surface of a light emitting unit, and FIG. 2B is a partial cross-sectional view of a light receiving unit.

FIG. 3 is a diagram illustrating types of reflected light when a measurement target is irradiated with P-polarized light.

FIG. 4 is a flowchart illustrating a control routine of a processing circuit.

FIG. 5A is a graph showing S-polarized light components,
(B) is a graph showing the P-polarized light component, and (C)
Is a graph showing heart rate information.

FIG. 6 is a heart rate graph.

[Explanation of symbols]

 Reference Signs List 12 light emitting unit (irradiating unit) 14 drive circuit (irradiating unit) 16 polarizing filter (irradiating unit) 18 lens (irradiating unit) 22 polarizing beam splitter (separating unit) 24 first light receiving unit (detecting unit) 26 second light receiving Section (detection means) 28 processing circuit (arithmetic means) 30 data analysis system

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeo Terada 41-Cho Chu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory, Inc. 41, Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Inventor Hiroshi Ito 41, Toyota-Chuo Research Laboratory, Nagakute-machi, Aichi-gun, Aichi, Japan (72) Inventor Morihiro Matsuda Aichi Prefecture 41 Toyota Chuo R & D Co., Ltd., No. 41, Nagachute-cho, Nagakute-cho, Aichi-gun (72) Inside the inventor Tetsuya Mizuno 1-1-1 Showa-cho, Kariya-shi, Aichi Pref. 14 Iwatani, Shimohazu-machi, Nishio-shi, Japan Inside the Japan Automotive Parts Research Laboratory

Claims (1)

[Claims] An irradiating means for irradiating a living body with linearly polarized light; and a reflected light reflected from the living body, the first linearly polarized light having an electric vector oscillating in the same direction as the linearly polarized electric vector. Separating means for separating the vector vibration direction into second linearly polarized light having a direction perpendicular to the electric vector of the linearly polarized light; and separating the first linearly polarized light and the second linearly polarized light separated by the separating means. Detecting means for detecting, the first linearly polarized light and the second linearly polarized light so that the difference between the moving component of the living body in the detection data of each of the first linearly polarized light and the second linearly polarized light detected by the detecting means is reduced. Processing the detection data of at least one of the two linearly polarized lights to calculate data corresponding to the detection data of each of the first linearly polarized light and the second linearly polarized light, and calculating the difference or A biological information detecting device comprising: a calculating means for calculating a quotient to obtain biological information.