JP6928906B2 - Biological information measuring device - Google Patents

Description

The present disclosure relates to a technique for measuring biological information.

Heart rate, blood flow, blood pressure, blood oxygen saturation, and the like are widely used as basic parameters for determining human health. These biometric information about blood is usually measured by a contact measuring instrument. Since the contact-type measuring device restrains the living body of the subject, it causes discomfort to the subject, especially when continuously measuring for a long period of time.

Patent Document 1 discloses a biological activity measuring device including a head fixing means for regulating the movement of the head of a subject. The head fixing means is, for example, a chin rest or an eye mask for fixing the chin or forehead. According to this configuration, since the movement of the head is restricted, the brain function can be measured accurately, but it causes discomfort to the subject when it is continuously measured.

Near infrared rays (electromagnetic waves in the wavelength range of about 700 nm to about 2500 nm) are often used to acquire biological information. Among them, near infrared rays having a relatively short wavelength (for example, about 950 nm or less) are particularly often used. _{Such near-infrared rays have the property of being easily absorbed by oxidized hemoglobin (HbO 2} ) and reduced hemoglobin (Hb) in blood while transmitting through living tissues such as muscle, fat and bone with relatively high transmittance. Have. Near-infrared spectroscopy (hereinafter referred to as "NIRS") is known as a method for measuring biological information utilizing such properties. By using NIRS, for example, the oxidized hemoglobin concentration and the reduced hemoglobin concentration in the blood in the brain can be measured. It is also possible to estimate the activity state of the brain (hereinafter, may be referred to as "brain function") based on the oxygen state of hemoglobin.

Patent Document 2 discloses an optical brain function measuring device that measures brain function using NIRS. This device includes a light source unit that generates infrared light, a photodetection unit that detects infrared light from the human body, and an optical system that controls the irradiation position of light on the human body. According to this configuration, it is disclosed that brain function can be measured at an arbitrary position on the human head.

Patent Document 3 discloses an environmental control system that appropriately controls the surrounding environment of a subject by obtaining data on brain activity at a plurality of measurement sites on the brain surface of the subject.

Japanese Unexamined Patent Publication No. 2003-337102 Japanese Unexamined Patent Publication No. 2015-134157 JP-A-2009-136495

G. Lopez et al. “Continuous blood pressure monitoring in daily life,” Journal of Advanced Mechanical Design, Systems, and Manufacturing 3 (1), 179.18.

However, in the above-mentioned conventional technique, there is a problem that biological information cannot be stably measured when the subject moves.

An exemplary embodiment, but not limited to, of the present application provides a technique capable of measuring biometric information even when the subject is moving.

The biological information measuring device according to one aspect of the present disclosure detects a light source that emits irradiation light for irradiating a test portion of a subject and light from the subject, and performs electricity corresponding to the light. It is provided with a light detector that outputs a signal and a control circuit that determines the power of the irradiation light emitted by the light source and measures biological information regarding blood flow in the test portion based on the electric signal. The control circuit detects the distance between the light source and the test portion based on the electric signal, and determines the power of the irradiation light so that the longer the distance, the greater the power of the irradiation light. do.

The above-mentioned comprehensive or specific embodiment may be realized by a system, a method, an integrated circuit, a computer program, or a recording medium. Alternatively, it may be realized by any combination of systems, devices, methods, integrated circuits, computer programs and recording media.

According to one aspect of the present disclosure, it is possible to measure biological information even when the subject moves.

FIG. 1A is a diagram schematically showing a schematic configuration of a biological information measuring device 100 according to the first embodiment. FIG. 1B is a diagram showing a more detailed configuration example of the biological information measuring device 100 according to the present embodiment. FIG. 1C is a diagram showing an example of light reflected and scattered by the subject O irradiated with the light 121. FIG. 2 is a diagram showing the wavelength dependence of the light absorption coefficients of oxidized hemoglobin (oxyhemoglobin), reduced hemoglobin (deoxyhemoglobin), and water. FIG. 3 is a diagram showing an internal configuration of the processing device 150. FIG. 4 is a diagram schematically showing a typical functional block of the control circuit 200. FIG. 5 is a diagram showing an example of processing of the biological information measuring device 100. FIG. 6 is a diagram schematically showing a modified example of the configuration of the light source. FIG. 7 is a diagram schematically showing a configuration example of a biological information measuring device 100 further provided with an image sensor 141 different from the photodetector 140. FIG. 8 is a diagram schematically showing an example of a pulse wave acquired by measurement. FIG. 9 is a diagram schematically showing pulse waves a and b obtained from, for example, two points of a face and a hand. FIG. 10A is a diagram schematically showing an example of an electronic device 400 to which the biometric information measurement module 300 according to the present embodiment is attached. FIG. 10B is a block diagram schematically showing the configuration of the biometric information measurement module 300 according to the present embodiment. FIG. 11 is a diagram schematically showing a typical functional block of the control circuit 200A of the biometric information measurement module 300. FIG. 12A is a diagram showing a state in which a learner O, who is a subject, is solving a problem in a department (for example, arithmetic, national language, etc.) using an electronic device 400. FIG. 12B is a diagram showing an example of a state in which the head of the learner O moves from the state of FIG. 12A. FIG. 13 is a diagram schematically showing the robot 500 and the interlocutor O who is the subject according to the fourth embodiment. FIG. 14 is a diagram showing a configuration example of the robot 500. FIG. 15 schematically shows the inside of the vehicle 600 according to the fifth embodiment. FIG. 16 schematically shows the appearance of the environment control device 700 according to the sixth embodiment.

Before explaining the embodiments of the present disclosure, the findings underlying the present disclosure will be described.

The inventor of the present application detects biological information (for example, information on cerebral blood flow) related to the blood of the subject, estimates the concentration ratio or emotion of the subject, and controls various devices based on the estimation result. I'm considering that. For example, in an educational application using a tablet terminal, we are studying control such as changing the display content according to the degree of concentration of the learner. Alternatively, we are considering control such as changing the content of the conversation according to the psychological state or concentration of the person who is communicating with the interactive robot by voice or video (expressed as conversation). In addition, depending on the control of the self-driving car according to the concentration of the driver, or the emotions of the people in the room (including the feeling of heat, cold, etc.), the set temperature of the air conditioner or the audio equipment We are also considering control such as changing the volume.

In order to realize such an interactive operation, it is desired to appropriately acquire biological information such as cerebral blood flow of a user (hereinafter, also referred to as "subject"). However, the subject is not always stationary and usually moves well. When the subject's subject (for example, forehead) moves, it becomes difficult to properly acquire biological information.

Since the devices of Patent Document 1 and Patent Document 3 are premised on a state in which the head is stationary, they cannot be applied to the above-mentioned applications.

In the measuring device of Patent Document 2, the power of the light source is always constant regardless of the distance between the subject and the photodetector. Therefore, the farther the photodetector is from the subject, the more the power of the reflected light and the scattered light from the subject is attenuated. As a result, the S / N ratio of the measuring device is lowered, and the detection accuracy of the biological information is lowered.

Based on the above considerations, the inventor of the present application has come up with a novel biometric information measurement technique disclosed below.

The present disclosure includes a biometric information measuring device, a biometric information measuring module, an integrated circuit, a biometric information measuring method, a computer program, an electronic device, a robot, a vehicle, and an environmental control device described in the following items.
[Item 1]
A light source that emits irradiation light to irradiate the subject's part,
A photodetector that detects light from the subject and outputs an electrical signal corresponding to the light.
A control circuit for determining the power of the irradiation light emitted by the light source and measuring biological information regarding blood flow in the test portion based on the electric signal is provided.
The control circuit detects the distance between the light source and the test portion based on the electric signal, and increases the power of the irradiation light so that the longer the distance, the greater the power of the irradiation light. Biometric information measuring device to determine.
[Item 2]
The control circuit further compares the first distance, which is the distance at the first time, with the second distance, which is the distance at the second time after the first time, and as a result of the comparison, the distance. If it is determined that the value has fluctuated, the power of the irradiation light is determined again.
The biometric information measuring device according to claim 1.
[Item 3]
The photodetector is an image sensor that acquires a moving image of the test portion including a plurality of frames.
The control circuit makes the comparison between the first distance and the second distance for each predetermined number of frames.
The biometric information measuring device according to claim 2.
[Item 4]
The control circuit further determines whether or not the measurement of the biological information is normal, and when it detects that the measurement cannot be performed normally, the comparison between the first distance and the second distance. I do,
The biometric information measuring device according to claim 2.
[Item 5]
The photodetector is an image sensor that acquires an image of the subject to be inspected.
The electrical signal includes a signal indicating the image.
Based on the signal showing the image, the control circuit uses the first brightness, which is the brightness of the test unit at the first time, and the brightness of the test unit at the second time after the first time. A brightness fluctuation amount, which is the difference between a certain second brightness and the first brightness and the second brightness, is detected, and the power of the irradiation light is adjusted according to the brightness fluctuation amount.
The biometric information measuring device according to claim 1.
[Item 6]
The image is a moving image including a plurality of frames.
The control circuit detects the brightness fluctuation amount for each predetermined number of frames.
The biometric information measuring device according to claim 5.
[Item 7]
The control circuit further determines whether or not the measurement of the biological information is normal, and detects the brightness fluctuation amount when it detects that the measurement cannot be performed normally.
The biometric information measuring device according to claim 5.
[Item 8]
The control circuit further detects a distance variation amount, which is the difference between the first distance, which is the distance at the first time, and the second distance, which is the distance at the second time after the first time. And the power of the irradiation light is adjusted according to the distance fluctuation amount.
The biometric information measuring device according to claim 1.
[Item 9]
The image is a moving image including a plurality of frames.
The control circuit detects the distance fluctuation amount for each predetermined number of frames.
The biometric information measuring device according to claim 8.
[Item 10]
The control circuit further determines whether or not the measurement of the biological information is normal, and detects the distance fluctuation amount when it detects that the measurement cannot be performed normally.
The biometric information measuring device according to claim 8.
[Item 11]
The control circuit further detects the position of the subject to be inspected based on the electric signal, and determines the position in which the irradiation light is irradiated in the subject based on the position.
The biometric information measuring device according to claim 1.
[Item 12]
The photodetector is an image sensor that acquires an image of the subject to be inspected.
The electrical signal includes a signal indicating the image.
The control circuit detects the position of the test portion by image recognition based on the signal indicating the image.
The biometric information measuring device according to claim 11.
[Item 13]
The biometric information measuring device includes a first photodetector and a second photodetector.
Each of the first photodetector and the second photodetector is the photodetector.
The second photodetector is an image sensor and
The first photodetector detects a component of the wavelength included in the irradiation light among the light from the subject, and outputs a first electric signal corresponding to the component of the wavelength.
The second photodetector detects a component of visible light in the light from the subject and outputs a second electric signal corresponding to the component of the visible light.
The control circuit detects the distance based on the second electric signal and measures the biological information based on the first electric signal.
The biometric information measuring device according to claim 1.
[Item 14]
The irradiation light is pulsed light.
The control circuit detects the distance based on the time from when the light source emits the pulsed light until the photodetector detects the pulsed light.
The biometric information measuring device according to claim 1.
[Item 15]
Further provided with an optical element arranged on the path of the irradiation light and changing the position of the subject to be irradiated with the irradiation light.
The control circuit controls the optical element based on the electric signal.
The biometric information measuring device according to claim 11.
[Item 16]
The subject is the forehead of the subject.
The biological information is information on cerebral blood flow.
The biometric information measuring device according to claim 1.
[Item 17]
Further comprising an interface for transmitting the electric signal output from the photodetector to an external device.
The biometric information measuring device according to claim 1.
[Item 18]
A light source that emits irradiation light to irradiate the subject's part,
A photodetector that detects light from the subject and outputs a first electrical signal corresponding to the light.
A control circuit that determines the power of the irradiation light emitted by the light source and measures biological information regarding blood flow in the test portion based on the first electric signal.
It is provided with an interface for acquiring an image of the part to be inspected and communicating with an external device including an image sensor that outputs a second electric signal including a signal indicating the image.
The interface receives the second electrical signal from the external device and transmits the first electrical signal to the external device.
Based on the second electric signal, the control circuit detects the distance between the light source and the test portion, and the longer the distance, the greater the power of the irradiation light. A biometric information measuring device that determines power.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, all the embodiments described below show comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement and connection forms of components, steps, step order, etc. shown in the following embodiments are examples, and are not intended to limit the present disclosure. The various aspects described herein can be combined with each other as long as there is no conflict. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components. In the following description, components having substantially the same function or similar functions may be designated by a common reference numeral, and the description may be omitted.

(Embodiment 1)
First, the biological information measuring device according to the first embodiment will be described. The biological information measuring device non-contactly measures the cerebral blood flow in the subject's part to be examined.

FIG. 1A is a diagram schematically showing a schematic configuration of a biological information measuring device 100 according to the first embodiment.

The biological information measuring device 100 includes a light source 110, a photodetector 140, and a control circuit 200 connected thereto. The light emitted from the light source 110 is reflected by the subject O's subject (forehead in the illustrated example) and is incident on the photodetector 140. The photodetector 140 converts the incident light into an electric signal and outputs it. The control circuit 200 adjusts the irradiation position and power of light by the light source 110 based on the signal output from the photodetector 140. Briefly, the control circuit 200 performs the following operations.
(1) The position of the test section and the distance to the test section are specified based on an electric signal (for example, a signal indicating an image) output from the photodetector 140 during light emission of the light source 110.
(2) Based on the position and distance of the specified test portion, the position and the power of light to be irradiated by the subject O are determined. For example, an optical element such as a MEMS mirror (not shown) is controlled so that the position of the test portion is correctly irradiated with light. Then, the light source 110 is made to emit light so that the power of the light reaching the photodetector 140 becomes substantially a specified value. For example, the larger the distance to the test portion, the higher the power of the light emitted by the light source 110, and the smaller the distance, the lower the power of the light emitted by the light source 110.

Here, a method of adjusting the power of light will be described. The power of light is defined by the energy of light per unit time, and the unit is watt (W) = joule / second (J / S).

When the irradiation light is continuous light, the light power can be controlled by controlling the intensity of the irradiation light. That is, the light power can be increased by increasing the intensity of the irradiation light. Further, the light power can be reduced by lowering the intensity of the irradiation light.

Further, when the irradiation time of continuous light is shorter than the unit time, the light power can be further controlled by the irradiation time control. The unit time may be, for example, 1 second. The light power can be increased by lengthening the irradiation time.

When the irradiation light is pulsed light, the optical power can be controlled by controlling the intensity of the irradiation light and further controlling the duty ratio of the pulse (the ratio of the irradiation time to the pulse period). By increasing the intensity of the irradiation light, the light power can be increased. The optical power can be increased by increasing the duty ratio of the pulse. Further, the light power can be reduced by lowering the intensity of the irradiation light.

Further, when the irradiation time of a group of pulsed light is shorter than the unit time, the optical power can be controlled by controlling the number of pulses. At this time, the optical power can be increased by increasing the number of pulses. Further, the optical power can be reduced by reducing the number of pulses.

The control circuit 200 first performs the above operation when the detection of biological information is started (at the time of initial operation). As a result, the part to be inspected is irradiated with light with an appropriate power, and biological information can be detected with high accuracy. However, in the same state, the detection cannot be continued when the subject O moves. Therefore, the control circuit 200 in the present embodiment performs the above operation at predetermined time intervals while detecting biological information. As a result, even if the subject O moves, the direction and power of the light are properly maintained, and the detection of biological information can be continued.

The above operation is not limited to the mode in which the operation is performed both at the time of the initial operation and during the detection, and may be performed at at least one of the timing of the initial operation and the timing of the detection. As a result, it is possible to detect biometric information with high accuracy regardless of the position of the test portion of the subject O at least during the initial operation and at least one of the detection times.

Hereinafter, the configuration and operation of the present embodiment will be described in more detail.

[1-1. Configuration of biological information measuring device 100]
FIG. 1B is a diagram showing a more detailed configuration example of the biological information measuring device 100 according to the present embodiment. In the biometric information measuring device 100 in this example, in addition to the light source 110, the light detector 140, and the control circuit 200 described above, the optical element 120 that changes the path of the light emitted from the light source 110 and the subject O It includes an optical system 130 that collects light, and a processing device 150 that processes a signal output from the light detector 140 and controls a light source 110 and an optical element 120. The control circuit 200 is provided inside the processing device 150. FIG. 1B also shows a display 160, which is an external element of the biometric information measuring device 100. The display 160 is connected to the processing device 200 and displays the processing result.

The details of each component will be described below.

The light source 110 irradiates the subject portion of the subject O with light. The subject portion in this embodiment is the amount of the subject O. By irradiating the forehead with light, information on cerebral blood flow can be obtained by detecting the reflected light or diffused light. The "scattered light" includes reflected scattered light and transmitted scattered light. In the following description, the reflected scattered light may be simply referred to as "reflected light". When acquiring blood information other than cerebral blood flow, a site other than the forehead (for example, an arm or a leg) may be used as the test site. In the following explanation, unless otherwise specified, the subject is assumed to be the forehead. In the following description, the subject O is assumed to be a human, but may be an animal having non-human skin and having a hairless portion. The term "subject" as used herein means a subject in general, including such animals.

The light source 110 emits light of, for example, 650 nm or more and 950 nm or less. This wavelength range is included in the wavelength range from red to near infrared rays. The above wavelength range is called the "window of the living body" and is known for its low absorption rate in the body. Although the light source 110 in the present embodiment will be described as emitting light in the above wavelength range, light in another wavelength range may be used. In this specification, the term "light" is used not only for visible light but also for infrared light.

FIG. 2 is a diagram showing the wavelength dependence of the light absorption coefficients of oxidized hemoglobin (oxyhemoglobin), reduced hemoglobin (deoxyhemoglobin), and water. In the visible light region of 650 nm or less, the _{absorption by hemoglobin (HbO 2} and Hb) in blood is large, and in the wavelength region longer than 950 nm, the absorption by water is large. On the other hand, in the wavelength range of 650 nm or more and 950 nm or less, the absorption coefficient of hemoglobin and water is relatively low, and the scattering coefficient is relatively large. Therefore, the light in this wavelength range enters the body, is strongly scattered, and returns to the body surface. Therefore, it is possible to efficiently acquire information in the body. Therefore, in this embodiment, light in this wavelength range is mainly used.

The light source 110 can be, for example, a laser light source such as a laser diode (LD) that continuously emits pulsed light. When the subject O is a person as in the present embodiment, it is required to consider the influence of the emitted light on the retina. When a laser light source is used as the light source 110, the light source 110 may be set so as to satisfy the class 1 of the laser safety standard established in each country. When Class 1 is satisfied, the subject O is irradiated with light having a low illuminance such that the exposure limit AEL is less than 1 mW. However, the light source 110 itself does not have to satisfy Class 1. For example, an element such as a diffuser plate or an ND filter may be arranged between the light source 110 and the subject O, and the light may be diffused or attenuated to satisfy Class 1 of the laser safety standard.

The light source 110 is not limited to a laser light source, and may be another type of light source such as a light emitting diode (LED). For the light source 110, for example, a semiconductor laser, a solid-state laser, a fiber laser, a superluminescent diode, an LED (Light Emitting Diode), and the like can be widely used. By combining these with the small optical element 120, the entire device can be miniaturized. The light source 110 is not limited to a light source that emits pulsed light, and may be a light source that emits continuous light.

The light source 110 starts and stops light emission and changes the light emission power in response to an instruction from the control circuit 200. The light 121 emitted from the light source 110 is used to detect information about cerebral blood flow and to detect the position and distance of the forehead.

The optical element 120 is arranged on the optical path of the light 121 between the light source 110 and the subject portion (that is, the forehead) of the subject O. The optical element 120 changes the optical path of the light 121 to guide the light 121 to the forehead. The optical element 120 adjusts the irradiation position of the light 121 on the forehead in response to the instruction from the control circuit 200. When the optical element 120 includes a mirror, the irradiation position of the light 121 on the forehead can be changed by changing the angle thereof.

The optical element 120 can be, for example, a MEMS (Micro Electro Mechanical Systems) mirror. In particular, if a two-axis scanning MEMS mirror is used, the light irradiation position in the test portion can be adjusted two-dimensionally. This makes it possible to adjust the light irradiation position in a small size and at high speed. For the optical element 120, for example, a polygon mirror, a galvano mirror, or a rotary prism may be used.

In the present specification, the combination of the light source 110 and the optical element 120 may be referred to as a "light source unit". The light source unit 170 including the light source 110 and the optical element 120 can be configured as, for example, one optical module. In the present specification, the light emitting direction from the light source unit 170 may be expressed as "the light emitting direction from the light source".

FIG. 1C is a diagram schematically showing how the reflected and scattered light (referred to as “return light”) reaches the photodetector 140 in the subject O irradiated with the light 121. The return light from the subject O is reflected once (including diffuse reflection), scattered, or multiple scattered inside the subject O with the component reflected on the surface of the subject O (surface reflection component I1). Includes a component (internal scattering component I2). Of these, the component to be detected is the internal scattering component I2. However, in general, the signal strength of the internal scattering component I2 is small. This is because, as mentioned above, in addition to being irradiated with a very small amount of light that meets the laser safety standards, there is a large amount of light scattering and absorption by the scalp, cerebrospinal fluid, skull, gray matter, white matter and bloodstream. Because. Furthermore, the change in signal intensity due to changes in blood flow or components in the blood flow during brain activity corresponds to a magnitude of one tenth, which is very small. Therefore, it is desirable to detect the surface reflection component I1, which is several thousand to tens of thousands times the signal component to be detected, with as little mixing as possible. Therefore, the detection circuit 140 may be composed of an image sensor having an electronic shutter function, and the control circuit 200 may appropriately control the shutter timing to detect only the diffuse reflection component I2. Such a configuration is disclosed, for example, in the specification of Japanese Patent Application No. 2015-122390. The entire disclosure of Japanese Patent Application No. 2015-122390 is incorporated herein by reference.

The optical system 130 collects the light 121 reflected or diffused by the test portion on the photodetector 140. The optical system 130 is, for example, a single lens or a plurality of lenses, and may include a mirror. When the optical system 130 includes a lens, antireflection films for suppressing reflection of light 121 may be provided on the light receiving side surface and the emitting side surface of the lens, respectively. This makes it possible to detect cerebral blood flow information with higher sensitivity.

The photodetector 140 detects the return light from the subject O. The photodetector 140 includes, for example, a plurality of photodetectors arranged in one or two dimensions. Each photodetector includes, for example, a photodiode, and outputs an electric signal according to the power (amount of light) of the light 121 from the test portion. The photodetector may be another device, such as a photomultiplier tube (PMT). When a highly sensitive avalanche photodiode or a photomultiplier tube is used as the photodetector, it is possible to acquire information on cerebral blood flow with higher sensitivity.

The photodetector 140 may be an image sensor such as a CCD or CMOS that is sensitive to light in a wavelength range including the wavelength of the light emitted from the light source 110. By using an image sensor, it is possible to acquire a two-dimensional intensity distribution of light (for example, a moving image). As will be described later, using the acquired moving image, a characteristic pattern of the test portion can be extracted by image recognition, and the position of the test portion in the image can be specified. Further, the movement of the test portion may be detected by motion detection.

The photodetector 140 also has a configuration capable of measuring the distance to the subject O. For example, the distance to the subject O can be measured by using TOF (Time-of-Flight) technology. In the TOF technique, the irradiation light is reflected by the subject O, and the time required for the reflected light to reach the photodetector 140, that is, the flight time is measured. The distance to the test portion of the subject O can be measured based on the difference between the phase of the light detected by each detection element and the phase of the light in the light source 110.

The optical system 130 and the photodetector 140 can be integrally configured. Further, the light source unit 170, the optical system 130, and the photodetector 140 may be integrally configured. This provides, for example, a portable small optical unit. The small optical unit can be connected to the processing device 150 with a cable such as a USB cable.

FIG. 3 is a diagram showing an internal configuration of the processing device 150.

The processing device 150 is connected to and controls a light source 110, an optical element 120, a detector 140, and a display 160. The processing device 150 includes a ROM (Read Only Memory) 152, a RAM (Random Access Memory) 153, and a control circuit 200. The control circuit 200 is an integrated circuit including, for example, a CPU (Central Processing Unit). The control circuit 200 controls the operation of the biological information measuring device 100. The ROM 152 stores a computer program executed by the control circuit 200. The computer program is a group of instructions for causing the control circuit 200 to perform, for example, the processing shown by the flowchart described later, or a part thereof. Such computer programs can be downloaded, for example, over a network and stored on a computer-readable recording medium. The RAM 153 is a work memory for expanding the program when the control circuit 200 executes the program. The RAM 153 is also a storage device that stores a signal (data) output from the photodetector 140 or data related to the measured biological information. As used herein, the term "biological information" means various information related to blood such as heartbeat, blood flow rate, blood pressure, and blood oxygen saturation. In particular, in this embodiment, the above information in cerebral blood flow is measured by the control circuit 200. Thereby, the state such as the concentration ratio or emotion of the subject O can be estimated.

The processing device 150 may be a general-purpose computer such as a personal computer or a tablet computer. Such a computer includes a CPU that controls the operation of the entire processing device 150. The CPU may perform some or all of the operations performed by the control circuit in the present disclosure. In that case, the CPU of the general-purpose computer functions as at least a part of the "control circuit" in the present disclosure.

The light source 110, the optical element 120, and the photodetector 140 can be connected to the processing device 150 via various interfaces. For example, if the photodetector 140 is an image sensor, it can be connected to the processing device 150 using terminals conforming to the MIPI standard (registered trademark). Further, the light source 110 and the optical element 120 can be connected to the processing device 150 by using, for example, a USB interface.

As shown, the processing device 150 may be connected to a display device 160 that displays a moving image of a subject and biological information. The display device 160 is a display such as a liquid crystal display or an organic EL. The display device 160 may be connected to the processing device 150 using, for example, HDMI® standard terminals. The user of the biological information measuring device 100 can obtain various information about the biological activity from the display device 160.

In addition to the wired connection described above, it is also possible to transmit and / or receive data by wireless communication. For example, communication conforming to the Wi-Fi® standard or the ZigBee® standard can be used.

The biological information measuring device 100 measures a two-dimensional intensity distribution of light, and measures various biological information such as blood flow, blood pressure, blood oxygen saturation, and heart rate in the brain based on the intensity distribution. Can be done. Such a measurement technique is disclosed in, for example, Patent Document 2, and can be suitably used for the present disclosure. For reference, all the disclosure contents of Patent Document 2 are incorporated herein by reference.

It is known that there is a close relationship between changes in cerebral blood flow or components in the bloodstream (eg, hemoglobin) and human neural activity. For example, changes in nerve cell activity in response to changes in human emotions change cerebral blood flow or components in the blood. Therefore, if biological information such as changes in cerebral blood flow or changes in blood components can be measured, the psychological state of the subject can be estimated. The subject's psychological state includes, for example, mood (eg, pleasure, discomfort), emotion (eg, relief, anxiety, sadness, resentment, etc.), health status (eg, energy, malaise), and temperature sensation (eg, hot). , Cold, sultry) and so on. Derived from this, indicators showing the degree of brain activity, such as proficiency, proficiency, and concentration, are also included in the psychological state.

[1-2. Operation of biometric information measuring device]
FIG. 4 is a diagram schematically showing a typical functional block of the control circuit 200. The control circuit 200 includes a detection unit 210, a light source control unit 220, a measurement unit 230, and an estimation unit 240. The control circuit 200 is an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). The function corresponding to each functional block can be implemented in the control circuit 200 by both software and hardware. For example, the internal ROM (not shown) of the control circuit 200 or the computer program stored in the ROM 152 may include a group of instructions for executing a function corresponding to each functional block. The control circuit 200 is a product that can be distributed on the market by itself.

FIG. 5 is a diagram showing an example of processing of the biological information measuring device 100. Hereinafter, it is assumed that the main body of operation is the control circuit 200, and the control circuit 200 executes the function corresponding to each functional block. As described above, when the CPU is provided separately from the control circuit 200, the CPU may execute a part of the functions of the control circuit 200. Hereinafter, the photodetector 140 will be described as being a TOF image sensor, and the optical element 120 will be described as being a MEMS mirror.

(Step S500)
The detection unit 210 of the control circuit 200 detects the position of the forehead of the subject O and the distance between the light source 110 and the forehead. Specifically, the detection unit 210 acquires the position information of the forehead in the frame image by image recognition by using a moving image output from the photodetector 140 and composed of a plurality of frame images. For example, the position of the forehead is specified by pattern matching using a template associated with the person's forehead. The position information can be, for example, information indicating the position of the center in the image in the detected pattern. The template is stored in the ROM 152 in advance, for example. A known method can be widely used for image recognition, and the method is not limited to a specific method. Further, the detection unit 210 calculates (distance measurement) the distance to the subject O based on the signal including the information indicating the phase difference of the power of the light output from the photodetector 140.

The light source control unit 220 of the control circuit 200 controls the light source 110 and the optical element 120 (that is, the light source unit 170).

The light source control unit 220 and the detection unit 210 execute the above-described operation as the initial operation of the biological information measuring device 100. Specifically, when the measurement of the biological information using the biological information measuring device 100 is started, the light source control unit 220 instructs the light source unit 170 to emit light. The light power and emission direction at this time are set to preset initial values. The detection unit 210 executes an initial operation and acquires initial information indicating the position and distance of the test unit. This initial operation corresponds to the calibration of the biological information measuring device 100.

(Step S501)
The light source control unit 220 sets the initial values of the light emission direction and the power based on the initial information from the detection unit 210. Specifically, the initial value of the light emission direction is set in the optical element 120. The optical element 120 sets, for example, the angle of the MEMS mirror to an angle corresponding to the initial value, and determines the irradiation position of the light 121 on the forehead. The initial value of the optical power is set in the light source 110. The light source 110 emits light 121 having a power corresponding to the initial value to the subject 0. By the above operation, regardless of the position of the subject O facing the biological information measuring device 100, light can be emitted with an appropriate power in an appropriate direction according to the position.

(Step S502)
The measurement unit 230 of the control circuit 200 measures the biological information of the subject O based on the output signal from the photodetector 140. For example, the measuring unit 230 uses NIRS to measure the oxidized hemoglobin concentration and the reduced hemoglobin concentration in the blood in the brain as biological information. The estimation unit 240 of the control circuit 200 estimates the psychological state of the subject based on the measured biological information. For example, the estimation unit 240 estimates the psychological state such as the concentration ratio and emotion of the subject O from the oxygen state of hemoglobin.

Here, a specific example of the method for measuring biological information will be described.

The major role of blood is to receive oxygen from the lungs and carry it to tissues, and to receive carbon dioxide from tissues and circulate it in the lungs. About 15 g of hemoglobin is present in 100 ml of blood. Hemoglobin bound to oxygen is oxidized hemoglobin, and hemoglobin not bound to oxygen is reduced hemoglobin. As shown in FIG. 2, the light absorption characteristics of oxidized hemoglobin and reduced hemoglobin are different. Oxidized hemoglobin absorbs infrared rays with wavelengths above about 830 nm relatively well, and reduced hemoglobin relatively strongly absorbs red light (eg, wavelengths at 660 nm). For near infrared rays with a wavelength of 805 nm, there is no difference in the absorption rates between the two. Therefore, in the present embodiment, two wavelengths of 660 nm (red light) and 830 nm (infrared light) are used, and the optical power from the test section is measured for each wavelength. From the power ratio of these red light and infrared light, the ratio of the concentrations of two types of hemoglobin (oxygen saturation) can be obtained. The combination of the two wavelengths used may be a combination of a wavelength less than 805 nm and a wavelength longer than 805 nm. Oxygen saturation is a value that indicates how much of the hemoglobin in the blood is associated with oxygen. Oxygen saturation is defined by the following formula, where C (Hb) is the concentration of reduced hemoglobin and C (HbO ₂ ) is the concentration of oxidized hemoglobin.
Oxygen saturation = C (HbO ₂ ) / [C (HbO ₂ ) + C (Hb)] x 100 (%)

In addition to blood, the living body contains components that absorb light with wavelengths from red to near infrared, but the light absorption rate fluctuates over time mainly due to hemoglobin in arterial blood. do. Therefore, the blood oxygen saturation can be measured with high accuracy based on the fluctuation of the absorption rate. Arterial blood pumped from the heart becomes a pulse wave and moves in the blood vessel. Venous blood, on the other hand, has no pulse wave. Light irradiated to a living body is absorbed by each layer of the living body such as arteries and veins and tissues other than blood and passes through the living body, but the thickness of tissues other than arteries does not change with time. Therefore, the scattered light from the living body shows a temporal intensity change according to the change in the thickness of the arterial blood layer due to the pulsation. This change reflects changes in the thickness of the arterial blood layer and does not include the effects of venous blood and tissues. Therefore, it is possible to obtain information on arterial blood by focusing only on the fluctuating component of scattered light. The pulse can also be determined by measuring the period of the component that changes with time.

When nerve cells are activated, oxygen carried by hemoglobin in the blood in the capillaries is consumed. It is known that an increase in blood flow occurs with a local reaction due to oxygen consumption. It is also known that reduced hemoglobin in capillaries temporarily increases by passing oxygen to living tissues. For example, it is assumed that the subject O is learning by solving a task. At that time, the cerebral blood flow may change from moment to moment depending on the degree of concentration. The higher the concentration, the higher the cerebral blood flow and the lower the blood oxygen saturation. Therefore, the estimation unit 240 can determine the concentration degree of the subject O based on, for example, the amount of change from the reference value of the cerebral blood flow rate or the blood oxygen saturation degree. In the present embodiment, a table for associating the amount of change from the reference value of cerebral blood flow or blood oxygen saturation with the degree of concentration is stored in ROM 152 in advance. The estimation unit 240 can determine the degree of concentration of learning from the measured biometric information by referring to the table. The measurement result of the measurement unit 230 and the estimation result of the estimation unit 240 are temporarily held in, for example, the RAM 153.

(Step S503)
As described above, for example, it is assumed that the subject O is learning by solving a certain task. At that time, it is assumed that the head of the subject O, that is, the forehead, which is the subject, moves during the measurement. Therefore, the detection unit 210 monitors whether or not the subject (particularly the head) has moved after performing the initial operation. For example, the detection unit 210 calculates a motion vector between consecutive frame images. The detection unit 210 determines that the subject O has moved when the magnitude of the motion vector is equal to or greater than the threshold value, and determines that the subject O has not moved when the magnitude of the motion vector is less than the threshold value. .. For example, the threshold value is stored in ROM 152 in advance.

The detection unit 210 does not have to sequentially determine the movement of the subject O, and may determine the movement for each predetermined number of frames (for example, 300 frames). As a result, the power consumption of the control circuit 200 can be suppressed.

When the detection unit 210 determines that the subject O has not moved, the process returns to step S502 again. Therefore, the setting of the light source unit 170 remains the default setting. When the detection unit 210 determines that the subject has moved, the process proceeds to step S505.

It should be noted that, without monitoring based on such a motion vector, for example, the measurement of the biological information in step S502 is repeatedly performed, and when it is detected that the measurement cannot be performed normally, the operation proceeds to step S505. good. Alternatively, the position and distance may simply be rediscovered at predetermined time intervals (eg, seconds to minutes).

Here, whether or not the measurement is normal can be determined by measuring the signal level of the electric signal corresponding to the blood flow of the test portion input to the control circuit. As the distance between the light source 110 and the test section increases, the level of the electric signal decreases and the SN ratio of the electrical signal deteriorates. Therefore, when the signal level falls below a predetermined value, the light source 110 and the test section The light power is increased so that the SN ratio is within a predetermined range by rediscovering the distance of.

On the other hand, the shorter the distance between the light source 110 and the test section, the more saturated the electrical signal. Therefore, when the signal level exceeds a predetermined value, the distance between the light source 110 and the test section is re-detected. The power of light is reduced so that the signal level is equal to or less than a predetermined value and the SN ratio of the signal is within a predetermined range.

(Step S505)
The detection unit 210 re-detects the position of the forehead of the subject O and the distance between the light source 110 and the forehead, and generates update information regarding the position and distance.

(Step S506)
The light source control unit 220 adjusts the light emission direction and the light power based on the update information from the detection unit 210. Specifically, the updated value of the light emission direction is set in the optical element 120, and the updated value of the optical power is set in the light source 110. The optical element 120 changes the angle of the MEMS mirror to an angle according to the updated value, and changes the irradiation position of the light 121 on the forehead. The light source 110 changes the optical power to the optical power value indicated by the updated value. When the setting of the light source unit 170 is updated, the process returns to step S502 again.

By the above operation, the setting of the light source unit is optimized at the time of the initial operation and during the measurement of the biological information. In this embodiment, the above optimization is performed both during the initial operation and during the measurement of biological information, but the present disclosure is not necessarily limited to such an embodiment. The above optimization may be performed at at least one of the initial operation and the measurement of biological information.

[1-3. Modification example]
Subsequently, a modified example of the present embodiment will be described.

FIG. 6 schematically shows a modified example of the configuration of the light source. The biological information measuring device in this modification includes two light sources 110 and 111. The two light sources 110 and 111 are connected to the control circuit 200.

Light in a wavelength band different from that of the light source 110 and the light source 111 is emitted. The wavelengths of the light emitted by the light source 110 and the light source 111 can be, for example, the above-mentioned 650 nm and 830 nm. However, the combination is not limited to this wavelength combination, and various combinations can be adopted. When the measurement target is a living tissue as in the present embodiment, as shown in FIG. 2, when the wavelength is larger than 805 nm, the absorbance by the oxidized hemoglobin is larger than the absorbance by the reduced hemoglobin. On the other hand, when the wavelength is less than 805 nm, the opposite characteristic is exhibited. Therefore, for example, it is assumed that the light source 110 emits light having a wavelength near 750 nm and the light source 111 emits light having a wavelength near 850 nm. In this case, if the light powers of the internal scattering component I2 due to the light from the light source 110 and the internal scattering component I2 due to the light from the light source 111 are measured, the initial values of the blood concentrations _{of HbO 2 and Hb can be solved by solving a predetermined simultaneous equations.} The amount of change from can be obtained.

The control circuit 200 solves simultaneous equations using the respective optical powers of the internal scattering component I2 due to the light from the light source 110 and the internal scattering component I2 due to the light from the light source 111, so that, for example, the initial blood concentration of _{HbO 2 and Hb} Calculate the amount of change from the value. Apart from the control circuit 200, an arithmetic circuit (not shown) for solving the simultaneous equations may be provided separately.

In the above example, the number of light sources is two, but three or more light sources having different wavelength bands of emitted light may be used. Alternatively, a light source whose wavelength band of light can be changed may be used. With such a configuration, more biometric information about blood can be obtained.

FIG. 7 is a diagram schematically showing a configuration example of a biological information measuring device 100 further provided with an image sensor 141 different from the photodetector 140. As described above, the biometric information measuring device 100 may include another image sensor 141 independent of the photodetector 140. According to this configuration, the photodetector 140 is used, for example, as a sensor specialized for measuring biological information, and the position and distance of the test portion can be detected based on the output signal from the image sensor 141. The control circuit 200 may detect the movement of the subject by using a moving image based on the output signal of the image sensor 141. Alternatively, the control circuit 200 may detect the distance based on the output signal of the photodetector 140 and detect the position based on the output signal of the image sensor 141, or vice versa. In the present specification, the photodetector 140 may be referred to as a "first photodetector" and the image sensor 141 may be referred to as a "second photodetector". Further, the electric signal output from the first photodetector may be referred to as a "first electric signal", and the electric signal output from the second photodetector may be referred to as a "second electric signal".

The biological information measuring device 100 according to the present embodiment can also measure biological information other than cerebral blood flow. Some specific examples will be described below.

When the blood flow changes, the reflectance of light changes. Utilizing this, for example, by irradiating an exposed test portion such as a face and a hand with near-infrared light and detecting the reflected light, the pulse rate and the degree of concentration can be measured in a non-contact manner. The control circuit 200 detects the initial information of the position and distance of the test portion according to the flow shown in FIG. 5 described above, and then determines the initial values of the light emission direction and the light power based on the initial information in the light source unit 170. Set to. The control circuit 200 then adjusts the light emission direction and the light power according to the movement of the test unit while monitoring the movement of the test unit.

FIG. 8 schematically shows an example of a pulse wave acquired by measurement. When measuring the pulse rate, the measuring unit 230 generates a pulse wave having a periodic curve based on, for example, an output signal from the photodetector 140. For example, the measuring unit 230 counts the maximum value of the pulse wave and calculates the time difference (referred to as “pulse wave period”) between two adjacent maximum values as shown in the figure. The measuring unit 230 converts the period of the pulse wave into a reciprocal and calculates the pulse rate.

The estimation unit 240 of the control circuit 200 can measure the variance of the pulse wave cycle in a predetermined period and determine a mental state such as concentration or relaxation. In general, when concentrated or tense, the pulse wave cycle tends to approach constant, and when relaxed, the pulse wave cycle tends to fluctuate. Therefore, the estimation unit 240 determines that the subject O is in a concentrated state or a tense state if the variance of the period is less than a predetermined value. With breathing, the variance gradually increases and may exceed a predetermined value. In that case, the estimation unit 240 can determine that the subject O is in a relaxed state.

Further, the biological information measuring device 100 can be used to measure blood vessel age, blood pressure, and the like in a non-contact manner. Specifically, the pulse wave velocity (PWV) is measured using the biological information measuring device 100. PWV is obtained by measuring the pulse waves of the face and hands and dividing the time difference of the pulse waves by the distance between them.

For example, PWV can be obtained by irradiating two exposed parts of the face and hands with near-infrared light and detecting the reflected light. Alternatively, for example, the PWV can be obtained by irradiating two exposed parts of the hand and ankle with near-infrared light and detecting the reflected light. It should be noted that, as the two test portions, locations that are separated from each other can be arbitrarily designated. It will be possible to measure vascular age and blood pressure in a non-contact manner based on PWV. The control circuit 200 detects the initial information of the position information and the distance information of the two test portions according to the flow shown in FIG. 5 described above, and then starts the light emission direction and the initial light power based on the initial information. Set the value to the light source unit 170. After that, the control circuit 200 adjusts the light emission direction and the optical power according to the movement of each test unit while monitoring the movement of each of the two test units during measurement.

FIG. 9 schematically shows pulse waves a and b obtained from, for example, two points on the face and hands. The measurement point A is located on the face and the measurement point B is located on the hand. For example, the measurement unit 230 of the control circuit 200 calculates PWV from the following equation (1) using the time difference ΔT at the rising points of the pulse waves of the measurement points A and B and the distance D between the two points.
PWV = D / ΔT equation (1)

For example, the estimation unit 240 of the control circuit 200 can estimate the blood vessel age and blood pressure based on PWV. For example, a table showing the average value of PWV for each age (generation) is stored in ROM 152 in advance. The estimation unit 240 can refer to the table to identify which age the PWV value obtained by the measurement is closest to the average value, and can estimate the blood vessel age of the subject O. In addition, the estimation unit 240 can estimate the blood pressure from the PWV. For example, a method for estimating blood pressure using PWV disclosed in Non-Patent Document 1 can be used.

When a contact-type measuring device is used, the method of attaching or pressing the sensor portion against the body may affect the measurement result. If the measurement can be performed in a non-contact manner as in the present embodiment, such a problem can be solved and the measurement can be simplified.

According to the present embodiment, the control circuit 200 adjusts the light irradiation position and the light power according to the position and distance of the test portion. Therefore, during the measurement, the subject O can spend a relatively free posture without being restrained by the device. Moreover, since it is possible to irradiate light having an appropriate power at an appropriate position, a high-quality signal can be obtained. As a result, the S / N ratio can be improved. Further, since the control circuit 200 monitors the movement of the subject O, even if the subject O moves a little during the measurement, the biological information can be stably measured. Therefore, for example, the subject O can receive the measurement while working.

(Embodiment 2)
Next, the biometric information measurement module according to the second embodiment will be described. The biometric information measurement module in this embodiment is an attachment used externally to a general-purpose portable electronic device such as a tablet terminal, a smartphone, or a notebook PC (laptop). Hereinafter, the points different from the biological information measuring device 100 according to the first embodiment will be mainly described, and the description of common parts will be omitted.

FIG. 10A is a diagram schematically showing an example of an electronic device 400 to which the biometric information measurement module 300 according to the present embodiment is attached. As shown, the biometric information measurement module 300 is used by being connected to the electronic device 400. The module 300 has a light source 110 and a photodetector 140. Although not shown in FIG. 10A, an optical element 120 such as a MEMS mirror and a control circuit 200A are provided inside the housing of the module 300. In the example of FIG. 10A, the module 300 is connected to the lower part of the electronic device 400, but the present invention is not limited to this. The position to be connected depends on the position of the connector of the electronic device 400. In the present embodiment, the moving image information acquired by the camera 450 of the electronic device 400 can be used.

With such a configuration, for example, a module 300 including a light source 110 and a photodetector 140 specialized for biometric information measurement (that is, detecting infrared light) is attached to an electronic device 400 such as a tablet terminal or a smartphone. A new usage method is possible. The camera 450 built into the electronic device 400 detects the movement of the subject O, and the control circuit 200A in the module 300 adjusts the emission direction and power of the light source 110 based on the detection signal. obtain.

The camera 450 built into a device such as a tablet terminal or a smartphone usually has an infrared (IR) cut filter in front of the image sensor. Therefore, the camera 450 cannot receive infrared light. On the other hand, the photodetector 140 of the module 300 may not include an infrared cut filter but may include a visible light cut filter in order to detect near-infrared light suitable for measuring biological information. Therefore, the detection of biological information can be performed by the photodetector 140 of the module 300, and the position and distance of the test portion that can be detected even with visible light can be specified by the camera 450 of the electronic device 400.

Here, the photodetector 140 of the biometric information measurement module 300 may detect not only the biometric information but also the distance between the light source 110 and the test portion. The position of the subject to be inspected can be detected by the camera 450 of the electronic device 400. The camera 450 of the electronic device 400 that operates with visible light can operate only with ambient light without irradiation light from the light source, and since the light source consumes a large amount of power, there is an effect that the total power consumption of the electronic device can be reduced. ..

FIG. 10B is a block diagram schematically showing the configurations of the biometric information measurement module 300 and the electronic device 400 in the present embodiment. The biometric information measurement module 300 detects light in a light source 110, an optical element 120, an optical system 130 (not shown), a photodetector 140, a control circuit 200A, a ROM 152, a RAM 153, and an external electronic device 400. It has an input / output interface (I / F) 250 for transmitting the output signal of the device 140. The module 300 may have a minimum number of components to operate as a module, as shown.

In addition to the camera 450, the electronic device 400 includes a display 456, a control circuit 454, a ROM 452, a RAM 453, and an input / output interface 440. The control circuit 454 may include, for example, a CPU and a digital signal processor (DSP) for image processing. The control circuit 454 analyzes the image acquired by the camera 450, controls the display of the display 456, and the like. The control circuit 454 operates in cooperation with the module 300 by executing a computer program (application) installed in advance. For example, the control circuit 454 causes the control circuit 200A of the module 300 to perform the measurement of the biometric information using the light source 110, the optical element 120, and the photodetector 140 when the biometric information is measured. At the same time, the control circuit 454 causes the camera 450 to take a picture of the subject O, and calculates the position and distance of the test part based on the acquired image. The control circuit 454 sends the information to the control circuit 200A of the module 300. Upon receiving this, the control circuit 200A adjusts the light emitting power of the light source 110 and the angle of the optical element 120 (that is, the light emitting direction) based on the position and distance information. As a result, light of an appropriate power is emitted in an appropriate direction following the movement of the test portion.

The output I / F 250 can be, for example, a USB interface. The output I / F may be another interface, for example, a wireless communication interface compliant with the Wi-Fi® standard or the ZigBee® standard.

FIG. 11 is a diagram schematically showing a typical functional block of the control circuit 200A of the biometric information measurement module 300. The control circuit 200A includes a CPU 180, a detection unit 210, and a light source control unit 220. The control circuit 200A is different from the control circuit 200 in the first embodiment in that the measurement unit 230 and the estimation unit 240 are not included. The CPU 180 controls the operation of the biometric information measurement module 300. The functions of the detection unit 210 and the light source control unit 220 are as described in the first embodiment.

The biometric information measurement module 300 can be connected to an external electronic device 400 via, for example, a USB cable connected to the output I / F 250. An application that executes the signal processing in the present disclosure (for example, the above-mentioned position and distance measurement processing and the processing corresponding to step S502 in FIG. 5) is installed in the electronic device 400. As a result, the processor of the electronic device 400 can receive the output signal of the photodetector 140 from the biometric information measurement module 300 and measure the biometric information based on the output signal. In addition, the psychological state of the subject can be estimated based on the biological information.

According to this embodiment, a biometric information measurement module that can be attached to and detached from an external electronic device 400 is provided.

(Embodiment 3)
Next, an embodiment of a learning system to which the technique of the present disclosure is applied will be described.

FIG. 12A is a diagram showing a state in which a learner O, who is a subject, is solving a problem in a department (for example, arithmetic, national language, etc.) using an electronic device 400. The electronic device 400 in this embodiment is a tablet computer (hereinafter referred to as a tablet PC). In addition to the tablet PC, the electronic device 400 can be any device having a display, such as a mobile phone, a smartphone, a notebook PC (laptop), an electronic book terminal, an electronic dictionary, or an electronic notebook.

The electronic device 400 may be the one to which the module 300 according to the third embodiment is attached, or may be a dedicated terminal having a built-in function of the module 300.

An educational system using a tablet PC as shown can be used, for example, in an educational institution such as a school or a private school, or at home. Learner O (for example, a child) learns using an application that displays subject problems such as math or Japanese on the display of a tablet PC.

An application (software) for displaying the problem of the department is pre-installed in the electronic device 400. The application may be downloaded via a telecommunication line such as the Internet. When the processor (control circuit) of the electronic device 400 executes the application, operations such as display of a question, display of correct answers and explanations after the answer, and transition to the next question are realized.

The control circuit of the electronic device 400 in the present embodiment detects biological information such as cerebral blood flow, blood oxygen saturation, or pulse wave cycle dispersion while the learner O is solving the problem. Monitor the concentration of learner O. The method for determining the degree of concentration is as described in the first embodiment. When the control circuit of the electronic device 400 detects a decrease in the concentration of the learner O, for example, it displays information that is of interest to the display or displays a simple problem to prevent the decrease in the concentration. As a result, the learning effect can be enhanced.

In a learning system such as the present embodiment, the learner O is not always stationary while the learner O is solving the problem. In particular, the learner O's head and body tend to move well when he / she does not understand the problem or lacks concentration. FIG. 12B shows an example of a state in which the head of the learner O moves from the state of FIG. 12A. As the learner O's head moves, the distance between the electronic device 400 and the subject (forehead) can also change. In such a case, in the prior art, there arises a problem that the light from the light source does not reach the forehead, or even if the light reaches the forehead, the detection accuracy is lowered due to the change in the distance.

On the other hand, the control circuit of the electronic device 400 of the present embodiment detects the position of the forehead of the learner O and the distance to the forehead during the initial operation (that is, at the start of light emission) and during the operation, and detects the position and the distance to the forehead. Adjust the light emission direction and power according to the position and distance. As a result, the forehead of the learner O is irradiated with light of an appropriate power, and the degree of concentration can be appropriately measured. If such adjustment is performed at the start of light emission of the light source and at predetermined times during light emission, it is possible to always irradiate light with an appropriate power by following the movement of the forehead.

The electronic device 400 according to the present embodiment includes the biological information measuring device 100 according to the first embodiment. The electronic device 400 irradiates the forehead of the subject O with infrared light, and uses NIRS to estimate the degree of concentration of learning of the subject O. The subject O solves and learns the problem displayed on the display screen of the electronic device 400 while operating with the stylus. As described above, when the subject O is solving the problem, the cerebral blood flow rate and the like change according to the degree of concentration of the subject O due to the activity of nerve cells. The control circuit 200 estimates the concentration ratio of the subject O based on the change. For example, as described above, the degree of concentration can be determined by referring to the table.

In addition, the learning proficiency can be estimated from the temporal change of the concentration. The learning of factorization in mathematics will be explained as an example. At the beginning of learning, the subject learns the factorization formula and how to apply it. Since he is not accustomed to it at the beginning, the degree of concentration is large and the amount of change in cerebral blood flow over time is large. As you complete the problem, you will become accustomed to applying the formula, so the answer time will be faster and the amount of time change in cerebral blood flow will decrease. Learning proficiency can be determined from the temporal transition of the change curve of cerebral blood flow. In addition to the temporal transition of changes in cerebral blood flow, the accuracy of judgment can be improved by using information indicating the degree of shortening of the answering time.

It is assumed that the amount of fluctuation in the head of the subject O, who is the user of the electronic device 400, changes according to the difficulty level of the problem. For example, suppose that the angle of the head changes from the angle shown in FIG. 12A to the angle shown in FIG. 12B when the subject O is solving the task. Even in that case, since the control circuit 200 monitors the movement of the subject O, when the movement is detected, the light emission direction and the power can be adjusted.

According to the present embodiment, even while the subject O is working, it is possible to irradiate the subject portion with light having an appropriate power at an appropriate position, and to stably measure biological information.

(Embodiment 4)
Next, the interactive robot according to the fourth embodiment will be described.

FIG. 13 is a diagram schematically showing the robot 500 and the interlocutor O who is the subject according to the fourth embodiment. FIG. 14 is a diagram showing a configuration example of the robot 500.

The robot 500 according to the present embodiment has the same components as the biological information measuring device 100 according to the first embodiment mounted on its head. The robot 500 detects the position and distance of the forehead of the subject O, irradiates the forehead with light having an appropriate light power, and estimates the emotion of the subject O using NIRS. The robot 500 can adjust the light irradiation position by moving the head following the movement of the subject O. Since the robot 500 faces the other party during the dialogue, it is a natural act to adjust the light irradiation position by moving the head.

As shown in FIG. 14, in the robot 500, in addition to the components described in the embodiment, at least one motor 520 for driving each part including the head, a speaker 530 for outputting voice, and an interlocutor O are emitted. It includes a microphone 540 that detects the sound, a camera 550, and a control circuit 510 that controls each part. The control circuit 510 detects the position of the test unit (for example, the forehead) and the distance to the test unit in the interlocutor O by performing the same operation as the control circuit 200 in the first embodiment. Then, based on the detection result of the photodetector 140, biological information such as cerebral blood flow is measured. Based on the biological information, a control signal for controlling elements such as the motor 520 and the speaker 530 is generated. The robot 500 can perform various operations based on the control signal. For example, if it is detected that the concentration of the interlocutor O is reduced during the voice dialogue using the speaker 530 and the microphone 540, the topic may be changed or the voice dialogue may be stopped. can. The robot 500 estimates the emotions of the other party during the dialogue. Specifically, the control circuit 200 estimates emotions based on changes in cerebral blood flow caused by neural activity. For example, the control circuit 200 can estimate emotions by referring to a table that associates changes in cerebral blood flow with emotions (for example, relief, anxiety, sadness, resentment, etc.). The robot 500 can change the topic with the interlocutor, for example, according to the emotion estimation result.

The control circuit 510 can adjust the light emission direction by controlling the movement of the head according to the position and distance of the test portion. Further, the head of the robot 500 and the optical element 120 arranged in front of the light source 110 may be combined to control the light emission direction. For example, the movement of the head can be controlled to roughly adjust the light emitting direction, and then the light source unit 170 can be controlled to finely adjust the light emitting direction. The optical element 120 may be omitted if it is unnecessary.

The program (application) that defines the operation of the present embodiment can be downloaded through, for example, a telecommunication line and installed in the robot 500. As a result, it is possible to improve the operation by updating the application.

According to this embodiment, appropriate communication can be achieved in the dialogue with the robot.

(Embodiment 5)
FIG. 15 schematically shows the inside of the vehicle 600 according to the fifth embodiment.

The vehicle 600 according to the present embodiment includes, for example, the biometric information measuring device 100 according to the embodiment at or near the position where the drive recorder is attached. The biological information measuring device 100 can be attached to the attachment portion 610 of the vehicle 600. The driver can freely attach / detach the biological information measuring device 100. The vehicle 600 includes not only automobiles but also trains and other mobile objects that need to be driven. In the present embodiment, the subject O is a driver.

The biological information measuring device 100 irradiates the forehead of the subject O with infrared light, and estimates the concentration ratio and the health state of the subject O using NIRS. The vehicle 600 includes a control circuit 620 that controls the operation of the vehicle 600. The control circuit 620 generates a control signal for the vehicle 600 based on the biometric information from the control circuit 200 of the biometric information measuring device 100. Alternatively, the control circuit 200 may generate a control signal for the vehicle 600 based on biological information, and the control circuit 620 may control the vehicle 600 based on the control signal. The vehicle comprises, for example, an automatic driving mode. If the vehicle is driving manually, the vehicle can receive a control signal to switch the driving mode from manual driving to automatic driving. For example, when it is detected that the concentration ratio of the driver O has decreased, the driver O may be dozing. Therefore, safety can be ensured by switching from manual operation to automatic operation.

The biological information measuring device 100 can also be linked with the car navigation system. For example, the biometric information measuring device 100 can transmit the information to the car navigation system when it is determined that the driver lacks concentration. The car navigation system can use, for example, a voice speaker or a display screen to warn of lack of concentration. The biometric information measuring device 100 does not always need to irradiate the driver with infrared light. For example, the driver is reddish by an instruction of a car navigation system (such as "turn right at an intersection 100 m ahead"). The degree of concentration of the driver may be determined by irradiating with external light. If there is no change in cerebral blood flow even with voice instructions from the car navigation system, there is a high possibility that the degree of concentration is lacking.

(Embodiment 6)
FIG. 16 schematically shows the appearance of the environment control device 700 according to the sixth embodiment.

The environmental control device 700 according to the present embodiment includes a biological information measuring device 100. The environmental control device 700 can be, for example, an air conditioner and audio. Such a device capable of controlling the environment around the user (temperature, sound, light, humidity, odor, etc.) is referred to as an "environmental control device" in the present specification. In the present embodiment, the subject O may be one or more users of the environmental control device 700.

The environmental control device 700 irradiates the forehead of the subject O with infrared light, and uses NIRS to estimate the psychological state of the subject O, specifically, the mood and temperature sensation.

The control circuit 200 of the biological information measuring device 100 monitors the movement of the subject O, and first identifies the subject O. After that, the control circuit 200 identifies the position of the subject portion (for example, the forehead) of the subject O by image recognition, and starts irradiating the forehead with infrared light.

The environment control device 700 includes a control circuit 710. The control circuit 710 generates a control signal of the environment control device 700 based on the biometric information from the control circuit 200 of the biometric information measuring device 100. Alternatively, the control circuit 200 may generate a control signal of the environment control device 700 based on the biological information, and the control circuit 710 may control the environment control device 700 based on the control signal. For example, it is assumed that the biological information measuring device 100 detects the discomfort of the subject O. When the environmental control device 700 is an air conditioner, the environmental control device 700 can automatically turn on the power and start the operation, or lower or raise the set temperature during the operation. When the environment control device 700 is an audio device, the environment control device 700 may automatically lower the volume, or may automatically select music (classical music or the like) that is expected to have a relaxing effect.

(Embodiment 7)
The biometric information measuring device according to the seventh embodiment will be described focusing on the differences from the biometric information measuring device 100 of the first embodiment.

Consider a case where the irradiation light from the light source 110 is divergent light instead of parallel light. When the divergent light is irradiated so that the entire test portion is exposed to the irradiation light and the image of the test section is acquired by the image sensor, the inventors of the present application detect the distance between the light source 110 and the test section. However, it was found that the detection accuracy of the presence or absence of movement of the subject is higher when the amount of brightness fluctuation in the subject is detected. That is, the difference between the seventh embodiment and the biometric information measuring device 100 of the first embodiment is that the amount of luminance fluctuation is detected.

Specifically, as compared with the first embodiment, the photodetector 140 is an image sensor, and the operations of steps S503 to S506 of the process shown in FIG. 5 are different.

Hereinafter, the operation of step S503 in the seventh embodiment will be described assuming that the main body of the operation is the control circuit 200 and the control circuit 200 executes the function corresponding to each functional block. As described above, when the CPU is provided separately from the control circuit 200, the CPU may execute a part of the functions of the control circuit 200. Hereinafter, the photodetector 140 will be described as being a TOF image sensor, and the optical element 120 will be described as being a MEMS mirror.

The detection unit 210 extracts the first luminance from the image of the test section acquired at the first time in the photodetector 140, and obtains the second luminance from the image of the test section acquired at the second time. Extract. The control circuit 200 calculates the amount of brightness fluctuation of the test unit between the first time and the second time from the first brightness and the second brightness. The detection unit 210 determines that the subject O has moved when the magnitude of the luminance fluctuation amount is equal to or greater than the threshold value, and determines that the subject O has not moved when the magnitude of the luminance fluctuation amount is less than the threshold value. For example, the threshold value is stored in ROM 152 in advance.

In the seventh embodiment, since the distance between the light source 110 and the test portion is not directly measured, step S505 of the first embodiment is unnecessary. After calculating the luminance fluctuation amount, the process proceeds to step S506. In step S506, the drive current fluctuation amount ΔJ of the light source 110 is determined according to the detected luminance fluctuation amount. When the drive current of the light source 110 at the first time is J1, the drive current of the light source 110 at the second time is set as J2 = J1 + ΔJ. When the irradiation light is divergent light, the amount of luminance fluctuation can be detected with high accuracy, so that the accuracy of the driving current fluctuation amount ΔJ of the light source 110 can be increased, and the adjustment accuracy of the light power can be improved.

Here, the brightness extracted from the image of the test section may be the average value of the brightness of the entire test section. However, the detection accuracy of the brightness fluctuation amount when the distance from the light source 110 to the test portion fluctuates is high when the distance fluctuation amount is small. Therefore, when determining the initial light power of the light source 110, the distance from the light source 110 to the test section is actually detected, the initial light power of the light source 110 is determined, and then the light source due to the movement of the test section. When adjusting the optical power of 110, it is preferable to detect the amount of brightness fluctuation.

(Embodiment 8)
The biometric information measuring device according to the eighth embodiment will be described focusing on the differences from the biometric information measuring device 100 of the first embodiment.

Consider a case where the irradiation light from the light source 110 is divergent light instead of parallel light. When the divergent light is irradiated so that the entire test portion is exposed to the irradiation light and the image of the test portion is acquired by the image sensor, the inventors of the present application perform the test rather than detecting the distance or the amount of distance fluctuation. It was found that the detection accuracy of the presence or absence of movement of the subject is higher when the amount of brightness fluctuation in the part is detected. That is, the difference between the seventh embodiment and the biometric information measuring device 100 of the first embodiment is that the amount of luminance fluctuation is detected.

The difference between the eighth embodiment and the biometric information measuring device 100 of the first embodiment is that the amount of distance variation between the light source 110 and the test unit is calculated.

Specifically, the operations of steps S503 to S506 of the process shown in FIG. 5 are different from those of the first embodiment.

Hereinafter, the operation of step S503 in the seventh embodiment will be described assuming that the main body of the operation is the control circuit 200 and the control circuit 200 executes the function corresponding to each functional block. As described above, when the CPU is provided separately from the control circuit 200, the CPU may execute a part of the functions of the control circuit 200. Hereinafter, the photodetector 140 will be described as being a TOF image sensor, and the optical element 120 will be described as being a MEMS mirror.

In step S503 of the eighth embodiment, the detection unit 210 acquires the first distance between the light source 110 and the test unit at the first time, and between the light source 110 and the test unit at the second time. Get the second distance. Based on the acquired first distance and second distance, the amount of distance fluctuation between the first time and the second time is calculated.

The detection unit 210 determines that the subject O has moved when the magnitude of the distance fluctuation amount is equal to or greater than the threshold value, and determines that the subject O has not moved when the magnitude of the distance fluctuation amount is less than the threshold value. For example, the threshold value is stored in ROM 152 in advance.

In the eighth embodiment, when it is determined that the subject O has moved, it is not necessary to detect the distance between the light source 110 and the subject portion again, so that step S505 is unnecessary. That is, when it is determined that the subject O has moved, the drive current fluctuation amount ΔI of the light source is determined according to the calculated distance fluctuation amount.

When the drive current of the light source at the first time is J1, the drive current of the light source at the second time is set as J2 = J1 + ΔJ. In general, since ΔJ is sufficiently smaller than J1, it is possible to set an upper limit value of a value sufficiently smaller than I1 for the fluctuation amount ΔI. Therefore, even if there is an error in detecting the distance, the amount of fluctuation in the drive current due to the detection error is small, so that malfunction of the light source such as irradiating light power other than the predetermined value can be reduced.

The present disclosure can be used for non-contact measurement of biological information, for example, biological / medical sensing, robots, vehicles, electronic devices, and the like.

100 Biometric information measuring device 110 Light source 120 Optical element 130 Optical system 140 Photodetector 150 Device body 180 CPU
152 ROM
153 RAM
160 Display device 170 Light source unit 180, 200, 510 Control circuit 250 Output I / F
300 Biological information measurement module 400 Electronic equipment 500 Robot 600 Vehicle 700 Environmental control device

Claims (20)

A light source that emits irradiation light to irradiate the subject's part,
A photodetector that detects light from the subject and outputs an electrical signal corresponding to the light.
A control circuit for determining the power of the irradiation light emitted by the light source and measuring biological information regarding blood flow in the test portion based on the electric signal is provided.
The control circuit
Based on the electric signal, the distance between the light source and the test portion is detected.
The power of the irradiation light is determined so that the longer the distance, the greater the power of the irradiation light .
Based on the electrical signal, a luminance fluctuation amount indicating the luminance fluctuation amount of the test portion between different times is detected.
The power of the determined irradiation light is adjusted based on the brightness fluctuation amount.
Biometric information measuring device. The control circuit further compares the first distance, which is the distance at the first time, with the second distance, which is the distance at the second time after the first time, and as a result of the comparison, the distance. If it is determined that the value has fluctuated, the power of the irradiation light is determined again.
The biometric information measuring device according to claim 1. The photodetector is an image sensor that acquires a moving image of the test portion including a plurality of frames.
The control circuit makes the comparison between the first distance and the second distance for each predetermined number of frames.
The biometric information measuring device according to claim 2. The control circuit further determines whether or not the measurement of the biological information is normal, and when it detects that the measurement cannot be performed normally, the comparison between the first distance and the second distance. I do,
The biometric information measuring device according to claim 2. The photodetector is an image sensor that acquires an image of the subject to be inspected.
The electrical signal includes a signal indicating the image.
The image is a moving image including a plurality of frames.
The control circuit detects the brightness fluctuation amount for each predetermined number of frames.
The biometric information measuring device according to claim 1. The control circuit further determines whether or not the measurement of the biological information is normal, and detects the brightness fluctuation amount when it detects that the measurement cannot be performed normally.
The biometric information measuring device according to claim 1. The control circuit further detects a distance variation amount, which is the difference between the first distance, which is the distance at the first time, and the second distance, which is the distance at the second time after the first time. And the power of the irradiation light is adjusted according to the distance fluctuation amount.
The biometric information measuring device according to claim 1. The photodetector is an image sensor that acquires an image of the subject to be inspected.
The electrical signal includes a signal indicating the image.
The image is a moving image including a plurality of frames.
The control circuit detects the distance fluctuation amount for each predetermined number of frames.
The biometric information measuring device according to claim 7. The control circuit further determines whether or not the measurement of the biological information is normal, and detects the distance fluctuation amount when it detects that the measurement cannot be performed normally.
The biometric information measuring device according to claim 7. The control circuit further detects the position of the subject to be inspected based on the electric signal, and determines the position in which the irradiation light is irradiated in the subject based on the position.
The biometric information measuring device according to claim 1. The photodetector is an image sensor that acquires an image of the subject to be inspected.
The electrical signal includes a signal indicating the image.
The control circuit detects the position of the test portion by image recognition based on the signal indicating the image.
The biometric information measuring device according to claim 10. The biometric information measuring device includes a first photodetector and a second photodetector.
Each of the first photodetector and the second photodetector is the photodetector.
The second photodetector is an image sensor and
The first photodetector detects a component of the wavelength included in the irradiation light among the light from the subject, and outputs a first electric signal corresponding to the component of the wavelength.
The second photodetector detects a component of visible light in the light from the subject and outputs a second electric signal corresponding to the component of the visible light.
The control circuit detects the distance based on the second electric signal and measures the biological information based on the first electric signal.
The biometric information measuring device according to claim 1. The irradiation light is pulsed light.
The control circuit detects the distance based on the time from when the light source emits the pulsed light until the photodetector detects the pulsed light.
The biometric information measuring device according to claim 1. Further provided with an optical element arranged on the path of the irradiation light and changing the position of the subject to be irradiated with the irradiation light.
The control circuit controls the optical element based on the electric signal.
The biometric information measuring device according to claim 10. The subject is the forehead of the subject.
The biological information is information on cerebral blood flow.
The biometric information measuring device according to claim 1. Further comprising an interface for transmitting the electric signal output from the photodetector to an external device.
The biometric information measuring device according to claim 1. The irradiation light is pulsed light.
The control circuit determines the power of the irradiation light by controlling the number of pulses of the pulsed light emitted by the light source.
The biometric information measuring device according to claim 1. The irradiation light is pulsed light.
The photodetector is an image sensor having an electronic shutter function.
By controlling the shutter timing of the electronic shutter, the control circuit causes the image sensor to detect the light scattered inside the test portion.
The biometric information measuring device according to claim 1. A diffuser plate that is arranged between the light source and the subject and diffuses the irradiation light is further provided.
The biometric information measuring device according to claim 1. A light source that emits irradiation light to irradiate the subject's part,
A photodetector that detects light from the subject and outputs a first electrical signal corresponding to the light.
A control circuit that determines the power of the irradiation light emitted by the light source and measures biological information regarding blood flow in the test portion based on the first electric signal.
It is provided with an interface for acquiring an image of the part to be inspected and communicating with an external device including an image sensor that outputs a second electric signal including a signal indicating the image.
The interface receives the second electrical signal from the external device and transmits the first electrical signal to the external device.
The control circuit
Based on the second electric signal, the distance between the light source and the test portion is detected.
The power of the irradiated light was determined so that the power of the irradiation light before Symbol distance longer increases,
Based on the first electric signal, a luminance fluctuation amount indicating the luminance fluctuation amount of the test portion between different times is detected.
The power of the determined irradiation light is adjusted based on the brightness fluctuation amount.
Biometric information measuring device.

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