Sony Patent | Biological information acquisition device, head-mounted information presentation device, and biological information acquisition method

Patent: Biological information acquisition device, head-mounted information presentation device, and biological information acquisition method

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Publication Number: 20210298615

Publication Date: 20210930

Applicant: Sony

Abstract

An object is to provide a technique for removing fluctuations caused by a change in posture of a target from which a blood flow velocity is acquired when measuring the blood flow velocity. The present technology provides a biological information acquisition device including: a blood flow velocity measurement unit that is installed on a head; a detection unit that detects a position change amount of the blood flow velocity measurement unit, a moving velocity of the blood flow velocity measurement unit, or the position change amount and the moving velocity of the blood flow velocity measurement unit; a correction information generation unit that generates correction information of a blood flow velocity on the basis of the position change amount, the moving velocity, or the position change amount and the moving velocity; and a correction unit that corrects the blood flow velocity measured by the blood flow velocity measurement unit using the correction information. Furthermore, the present technology also provides a head-mounted information presentation device and a biological information acquisition method.

Claims

1. A biological information acquisition device comprising: a blood flow velocity measurement unit that is installed on a head; a detection unit that detects a position change amount of the blood flow velocity measurement unit, a moving velocity of the blood flow velocity measurement unit, or the position change amount and the moving velocity of the blood flow velocity measurement unit; a correction information generation unit that generates correction information of a blood flow velocity on a basis of the position change amount, the moving velocity, or the position change amount and the moving velocity; and a correction unit that corrects the blood flow velocity measured by the blood flow velocity measurement unit using the correction information.

2. The biological information acquisition device according to claim 1, wherein the position change amount includes an amount of change in inclination of the blood flow velocity measurement unit or an amount of change in height of the blood flow velocity measurement unit.

3. The biological information acquisition device according to claim 1, wherein the position change amount includes an amount of change in inclination of the blood flow velocity measurement unit, and the inclination includes an angle projected onto a plane passing the blood flow velocity measurement unit and a center line of the head.

4. The biological information acquisition device according to claim 1, wherein the moving velocity includes an angular velocity of the blood flow velocity measurement unit or a velocity of the blood flow velocity measurement unit.

5. The biological information acquisition device according to claim 1, wherein the moving velocity includes an angular velocity of the blood flow velocity measurement unit.

6. The biological information acquisition device according to claim 1, wherein the correction information generation unit generates correction information for canceling a fluctuation in blood flow velocity caused by a change in position of the head, correction information for canceling a fluctuation in blood flow velocity caused by the moving velocity of the head, or correction information obtained by adding up the two pieces of correction information.

7. The biological information acquisition device according to claim 1, wherein the correction information generation unit generates correction information on a basis of the position change amount, a position characteristic correction parameter set on a basis of a relationship between a position of the blood flow velocity measurement unit and a blood flow velocity fluctuation amount, and/or a transient characteristic correction parameter related to transient characteristics of the blood flow velocity, and/or generates correction information on a basis of the moving velocity, a velocity characteristic correction parameter set on a basis of a relationship between the moving velocity of the blood flow velocity measurement unit and the blood flow velocity fluctuation amount, and/or the transient characteristic correction parameter related to the transient characteristics of the blood flow velocity.

8. The biological information acquisition device according to claim 7, wherein the biological information acquisition device further comprises a position characteristic correction parameter setting unit that sets and/or updates the position characteristic correction parameter.

9. The biological information acquisition device according to claim 8, wherein the position characteristic correction parameter setting unit sets and/or updates the position characteristic correction parameter before correction by the correction unit is performed.

10. The biological information acquisition device according to claim 8, wherein the position characteristic correction parameter setting unit sets and/or updates the position characteristic correction parameter on a basis of a relationship between a position change amount in a case where the position of the blood flow velocity measurement unit is changed to various different positions from a reference position and a blood flow velocity measured at each of the various different positions.

11. The biological information acquisition device according to claim 7, wherein the biological information acquisition device further comprises a velocity characteristic correction parameter setting unit that sets and/or updates the velocity characteristic correction parameter.

12. The biological information acquisition device according to claim 11, wherein the velocity characteristic correction parameter setting unit sets and/or updates the velocity characteristic correction parameter before correction by the correction unit is performed.

13. The biological information acquisition device according to claim 11, wherein the velocity characteristic correction parameter setting unit sets and/or updates the velocity characteristic correction parameter on a basis of a relationship between various moving velocities of the blood flow velocity measurement unit and a blood flow velocity measured at each of the various moving velocities.

14. The biological information acquisition device according to claim 7, wherein the biological information acquisition device further comprises a transient characteristic correction parameter setting unit that sets and/or updates the transient characteristic correction parameter.

15. The biological information acquisition device according to claim 14, wherein the transient characteristic correction parameter setting unit sets and/or updates the transient characteristic correction parameter before correction by the correction unit is performed.

16. The biological information acquisition device according to claim 14, wherein the transient characteristic correction parameter setting unit sets and/or updates the transient characteristic correction parameter by fitting a blood flow velocity estimated value estimated by using the position characteristic correction parameter to temporal blood flow velocity data temporally measured in a process of changing the position of the blood flow velocity measurement unit to another position from a reference position.

17. The biological information acquisition device according to claim 1, wherein the correction unit uses the correction information to cancel a fluctuation in blood flow velocity caused by a change in position of the head and/or a fluctuation in blood flow velocity caused by a moving velocity of the head.

18. A head-mounted information presentation device comprising: a blood flow velocity measurement unit that is installed on a head; a detection unit that detects a position change amount of the blood flow velocity measurement unit, a moving velocity of the blood flow velocity measurement unit, or the position change amount and the moving velocity of the blood flow velocity measurement unit; a correction information generation unit that generates correction information on a basis of the position change amount, the moving velocity, or the change amount and the moving velocity; and a correction unit that corrects the blood flow velocity measured by the blood flow velocity measurement unit using the correction information.

19. A biological information acquisition method comprising: a blood flow velocity measurement process of measuring a blood flow velocity of a head using a blood flow velocity measurement device installed on the head; a detection process of detecting a position change amount of the blood flow velocity measurement device, a moving velocity of the blood flow velocity measurement device, or the position change amount and the moving velocity of the blood flow velocity measurement device; a correction information generation process of generating correction information on a basis of the position change amount, the moving velocity, or the change amount and the moving velocity; and a correction process of correcting the blood flow velocity measured by the blood flow velocity measurement device using the correction information.

Description

TECHNICAL FIELD

[0001] The present technology relates to a biological information acquisition device, a head-mounted information presentation device, and a biological information acquisition method. More specifically, the present technology relates to a biological information acquisition device, a head-mounted information presentation device, and a biological information acquisition method that correct a measured blood flow velocity.

BACKGROUND ART

[0002] Biological information such as blood flow, blood pressure, heart rate, and body temperature is used to grasp the health state and/or psychological state of a person. Various devices have been proposed so far in order to acquire the biological information. For example, as a method for measuring blood flow, a method using laser Doppler flowmetry (hereinafter, also referred to as LDF), a method using ultrasonic waves, and a method using electromagnetic induction can be mentioned.

[0003] In order to acquire more accurate biological information, the measured biological information can be corrected. As an example of the technique related to such correction, for example, Patent Document 1 below discloses a blood pressure correction information generation device including a specific wrist position change period detection unit and a specific blood pressure correction information generation unit. The blood pressure correction information generated by the device corrects a measurement error of the blood pressure information caused by a change in the position of the wrist in the wrist-mounted blood pressure measurement device.

CITATION LIST

Patent Document

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-121273

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

[0005] The biological information not only fluctuates depending on the health state and/or the psychological state, but also fluctuates depending on the posture or moving velocity of a target from which the biological information is acquired. Therefore, in order to more accurately grasp the health state and/or the psychological state on the basis of the biological information, it is desirable that the biological information be corrected to remove fluctuations caused by a change in the posture of a biological information acquisition target or the moving velocity of the biological information acquisition target.

[0006] An object of the present technology is to provide a technique for removing fluctuations caused by a change in the posture of a target or the moving velocity of the target from which the blood flow velocity is acquired when measuring the blood flow velocity.

Solutions to Problems

[0007] The present technology provides a biological information acquisition device including:

[0008] a blood flow velocity measurement unit that is installed on a head;

[0009] a detection unit that detects a position change amount of the blood flow velocity measurement unit, a moving velocity of the blood flow velocity measurement unit, or the position change amount and the moving velocity of the blood flow velocity measurement unit;

[0010] a correction information generation unit that generates correction information of a blood flow velocity on the basis of the position change amount, the moving velocity, or the position change amount and the moving velocity; and

[0011] a correction unit that corrects the blood flow velocity measured by the blood flow velocity measurement unit using the correction information.

[0012] According to one embodiment of the present technology, the position change amount may be the amount of change in the inclination of the blood flow velocity measurement unit or the amount of change in the height of the blood flow velocity measurement unit. According to one embodiment of the present technology, the position change amount can include an amount of change in inclination of the blood flow velocity measurement unit, and the inclination can include an angle projected onto a plane passing the blood flow velocity measurement unit and a center line of the head.

[0013] According to one embodiment of the present technology, the moving velocity can include an angular velocity of the blood flow velocity measurement unit or a velocity of the blood flow velocity measurement unit.

[0014] Particularly preferably, the moving velocity can be the angular velocity of the blood flow velocity measurement unit.

[0015] According to one embodiment of the present technology, the correction information generation unit can generate

[0016] correction information for canceling a fluctuation in blood flow velocity caused by a change in position of the head,

[0017] correction information for canceling a fluctuation in blood flow velocity caused by the moving velocity of the head, or

[0018] correction information obtained by adding up the two pieces of correction information.

[0019] According to one embodiment of the present technology, the correction information generation unit can generate

[0020] correction information on the basis of the position change amount, a position characteristic correction parameter set on the basis of a relationship between a position of the blood flow velocity measurement unit and a blood flow velocity fluctuation amount, and/or a transient characteristic correction parameter related to transient characteristics of the blood flow velocity, and/or generate

[0021] correction information on the basis of the moving velocity, a velocity characteristic correction parameter set on the basis of a relationship between the moving velocity of the blood flow velocity measurement unit and the blood flow velocity fluctuation amount, and/or the transient characteristic correction parameter related to the transient characteristics of the blood flow velocity.

[0022] According to one embodiment of the present technology, the biological information acquisition device may further include a position characteristic correction parameter setting unit that sets and/or updates the position characteristic correction parameter.

[0023] The position characteristic correction parameter setting unit can set and/or update the position characteristic correction parameter before performing correction by the correction unit.

[0024] The position characteristic correction parameter setting unit can set and/or update the position characteristic correction parameter on the basis of the relationship between the position change amount in a case where the position of the blood flow velocity measurement unit is changed to various different positions from the reference position and the blood flow velocity measured at each of the various different positions.

[0025] According to one embodiment of the present technology, the biological information acquisition device may further include a velocity characteristic correction parameter setting unit that sets and/or updates the velocity characteristic correction parameter.

[0026] The velocity characteristic correction parameter setting unit can set and/or update the velocity characteristic correction parameter before performing correction by the correction unit.

[0027] The velocity characteristic correction parameter setting unit can set and/or update the velocity characteristic correction parameter on the basis of a relationship between various moving velocities of the blood flow velocity measurement unit and a blood flow velocity measured at each of the various moving velocities.

[0028] According to one embodiment of the present technology, the biological information acquisition device may further include a transient characteristic correction parameter setting unit that sets and/or updates the transient characteristic correction parameter.

[0029] The transient characteristic correction parameter setting unit can set and/or update the transient characteristic correction parameter before performing correction by the correction unit.

[0030] The transient characteristic correction parameter setting unit can set and/or update the transient characteristic correction parameter by fitting a blood flow velocity estimated value estimated by using the position characteristic correction parameter to temporal blood flow velocity data temporally measured in a process of changing the position of the blood flow velocity measurement unit to another position from a reference position.

[0031] According to one embodiment of the present technology, the correction unit can use the correction information to cancel a fluctuation in blood flow velocity caused by a change in position of the head and/or a fluctuation in blood flow velocity caused by a moving velocity of the head.

[0032] Furthermore, the present technology also provides a head-mounted information presentation device including:

[0033] a blood flow velocity measurement unit that is installed on a head;

[0034] a detection unit that detects a position change amount of the blood flow velocity measurement unit, a moving velocity of the blood flow velocity measurement unit, or the position change amount and the moving velocity of the blood flow velocity measurement unit;

[0035] a correction information generation unit that generates correction information on the basis of the position change amount, the moving velocity, or the change amount and the moving velocity; and

[0036] a correction unit that corrects the blood flow velocity measured by the blood flow velocity measurement unit using the correction information.

[0037] Furthermore, the present technology also provides a biological information acquisition method including:

[0038] a blood flow velocity measurement process of measuring the blood flow velocity of a head by a blood flow velocity measurement device installed on the head,

[0039] a detection process of detecting a position change amount of the blood flow velocity measurement device, a moving velocity of the blood flow velocity measurement device, or the position change amount and the moving velocity of the blood flow velocity measurement device,

[0040] a correction information generation process of generating correction information on the basis of the position change amount, the moving velocity, or the change amount and the moving velocity, and

[0041] a correction process of correcting the blood flow velocity measured by the blood flow velocity measurement device using the correction information.

[0042] According to the present technology, the measured blood flow velocity can be corrected so as to remove the fluctuation caused by a change in the posture of a measurement target or the moving velocity of the measurement target.

[0043] Note that effects provided by the present technology are not necessarily limited to effects described herein, but may also be any of those described in the present description.

BRIEF DESCRIPTION OF DRAWINGS

[0044] FIG. 1 is an example of a block diagram of a biological information acquisition device according to the present technology.

[0045] FIG. 2 is a model diagram for explaining a change in blood flow velocity.

[0046] FIG. 3 is a diagram showing an example of a position where a blood flow velocity measurement device is installed.

[0047] FIG. 4 is a diagram for explaining a change in inclination of a head.

[0048] FIG. 5 is a model diagram for explaining resistance and gravity acting on a red blood cell.

[0049] FIG. 6 is a diagram for explaining an example of a method of setting a position characteristic correction parameter.

[0050] FIG. 7 is a model diagram for explaining a change in blood flow velocity.

[0051] FIG. 8 is a diagram showing an example of a configuration of a head-mounted information presentation device according to the present technology.

[0052] FIG. 9 is a diagram showing an example of a configuration of a head-mounted information presentation device according to the present technology.

[0053] FIG. 10 is an example of a flow chart of biological information acquisition processing according to the present technology.

[0054] FIG. 11 is a graph showing a relationship between blood flow velocity and head inclination.

[0055] FIG. 12 is a graph showing blood flow velocity before and after correction.

[0056] FIG. 13 is an example of a block diagram of a biological information acquisition device according to the present technology.

[0057] FIG. 14 is a model diagram for explaining resistance and gravity acting on a red blood cell.

[0058] FIG. 15 is a diagram for explaining an example of a method of setting a velocity characteristic correction parameter.

[0059] FIG. 16 is an example of a block diagram of a biological information acquisition device according to the present technology.

[0060] FIG. 17 is an example of a flow chart of biological information acquisition processing according to the technology.

[0061] FIG. 18 is an example of a flow chart of biological information acquisition processing according to the technology.

[0062] FIG. 19 is a graph showing blood flow velocity before and after correction.

MODE FOR CARRYING OUT THE INVENTION

[0063] Preferred aspects for carrying out the present technology are described below. Note that embodiments described below indicate representative embodiments of the present technology, and the scope of the present technology is not limited to such embodiments. Note that the present technology will be described in the following order. [0064] 1. First embodiment (biological information acquisition device)

[0065] (1) Description of the first embodiment

[0066] (2) Example of configuration of the biological information acquisition device (correction based on position change amount of head)

[0067] (2-1) Correction information based on the amount of change in inclination

[0068] (2-2) Correction information based on the amount of change in height

[0069] (3) Example of configuration of the biological information acquisition device (correction based on moving velocity of head)

[0070] (3-1) Correction information based on angular velocity

[0071] (4) Example of configuration of the biological information acquisition device (correction based on position change amount and moving velocity of head) [0072] 2. Second embodiment (head-mounted information presentation device)

[0073] (1) Description of the second embodiment

[0074] (2) Configuration of the head-mounted information presentation device [0075] 3. Third embodiment (biological information acquisition method)

[0076] (1) Description of the third embodiment

[0077] (2) Example of the third embodiment (biological information acquisition method using position change amount of head)

[0078] (3) Example of the third embodiment (biological information acquisition method using moving velocity of head)

[0079] (4) Example of the third embodiment (biological information acquisition method using position change amount and moving velocity of head) [0080] 4. Example

[0081] (1) Correction based on position change amount

[0082] (2) Correction based on position change amount and moving velocity

1. FIRST EMBODIMENT (BIOLOGICAL INFORMATION ACQUISITION DEVICE)

[0083] (1) Description of the First Embodiment

[0084] A biological information acquisition device according to the present technology generates correction information on the basis of the position change amount of a blood flow velocity measurement unit installed on a head, the moving velocity of the blood flow velocity measurement unit, or both the position change amount and the moving velocity, and then corrects the blood flow velocity measured by the blood flow velocity measurement unit by using the correction information. Therefore, from the measured blood flow velocity of the head, the fluctuations in the blood flow velocity caused by a change in the position of the head and/or the moving velocity of the head, i.e., fluctuations in the blood flow velocity caused by a change in the posture of the person and/or the transition degree of the person can be removed. Thus, the biological information acquisition device according to the present technology can obtain blood flow velocity data that enables a more accurate grasp the health state and/or the psychological state of a person.

[0085] (2) Example of Configuration of the Biological Information Acquisition Device (Correction Based on Position Change Amount)

[0086] According to one embodiment of the present technology, the biological information acquisition device generates correction information on the basis of the position change amount of a blood flow velocity measurement unit installed on a head, and then corrects the blood flow velocity measured by the blood flow velocity measurement unit by using the correction information.

[0087] An example of the biological information acquisition device of this embodiment will be described below with reference to FIG. 1. FIG. 1 is an example of a block diagram of the biological information acquisition device of this embodiment.

[0088] As shown in FIG. 1, a biological information acquisition device 100 includes a blood flow velocity measurement unit 101, a detection unit 102, a processing unit 103, and an output unit 108. The processing unit 103 includes a correction information generation unit 104, a correction unit 105, a position characteristic correction parameter setting unit 106, and a transient characteristic correction parameter setting unit 107.

[0089] The blood flow velocity measurement unit 101 is installed on the head. The blood flow velocity measurement unit 101 may be configured to be able to measure the blood flow velocity of the head. A blood flow velocity measuring method used by the blood flow velocity measurement unit 101 may be a method known in the art, for example, any of a laser Doppler flowmetry (LDF) method, an ultrasonic method, and an electromagnetic induction utilization method. The blood flow velocity measurement unit 101 can include a blood flow velocity measurement device that measures the blood flow velocity by any of these methods. The blood flow velocity measurement device may be installed at any position on the head, for example, on the frontal head portion, the side head portion, or the rear head portion.

[0090] A more specific example of the blood flow velocity measurement device for measuring the blood flow velocity by the LDF method will be described below. The blood flow velocity device can include, for example, a laser light irradiation unit that irradiates the skin of the head with laser light, a detection unit that detects the light generated by the irradiation of the skin with the laser light, and a blood flow velocity calculation unit that calculates the blood flow velocity on the basis of the wavelength of the scattered light detected by the detection unit. Within the scattered light generated by the irradiation of the laser light, the frequency of the scattered light scattered by a stationary biological tissue is the same as the frequency of the irradiated laser light, while the frequency of scattered light scattered by scattering substances (mainly red blood cells) that move in the blood vessels of the skin of the head is subject to a slight Doppler shift. The interference light generated by the interference of these two scattered light is detected by the detection unit. The blood flow velocity calculation unit calculates the blood flow velocity by performing frequency analysis processing on the optical beat of the interference light.

[0091] The detection unit 102 detects the position change amount of the blood flow velocity measurement unit 101, particularly the position change amount of the blood flow velocity measurement device. In the present technology, the amount of change can be the amount of change in the inclination of the blood flow velocity measurement unit or the amount of change in the height of the blood flow velocity measurement unit.

[0092] The detection unit 102 can include, for example, an acceleration sensor, a gyro sensor, or a barometric pressure sensor. These sensors used in the present technology may be those known in the art. For example, any of these sensors can be provided in the biological information acquisition device 100 so that the position change is the same as the position change of the blood flow velocity measurement unit 101. For example, the positional relationship between the blood flow velocity measurement unit 101 and the detection unit 102 can be fixed. Therefore, the position change amount detected by the detection unit 102 can be treated as the position change amount of the blood flow velocity measurement unit 101.

[0093] Alternatively, the detection unit 102 may be a combination of a marker indicating the position of the blood flow velocity measurement unit 101 and a marker recognition device that recognizes the marker. The marker may be attached to the blood flow velocity measurement unit 101, or may be attached to the biological information acquisition device 100 so that the position change is the same as the position change of the blood flow velocity measurement unit 101. The marker recognition device can include an imaging element. By processing a still image or a moving image obtained by the imaging element, the position change amount of the marker can be measured. The position change amount of the marker can be treated as the position change amount of the blood flow velocity measurement unit 101.

[0094] The processing unit 103 can include a processor such as a CPU and a memory such as RAM and/or ROM. A program for causing the device to execute the biological information acquisition method according to the present technology, a position characteristic correction parameter and a transient characteristic correction parameter described below, a program for setting or updating these parameters, and the like can be stored in the memory. The function of the processing unit 103 can be realized by the processor.

[0095] The correction information generation unit 104 generates correction information on the basis of the position change amount of the blood flow velocity measurement unit 101 detected by the detection unit 102. Since the correction information is generated on the basis of the position change amount of the blood flow velocity measurement unit 101, it is suitable for canceling a change (increase/decrease) in the blood flow velocity caused by a change in the position of the head.

[0096] That is, according to one embodiment of the present technology, the correction information generation unit 104 can generate correction information for canceling fluctuations (for example, increase or decrease) of the blood flow velocity caused by a change in the position of the head. For example, the correction information generation unit 104 can generate correction information for canceling an increase in the blood flow velocity caused by lowering in the position of the head or correction information for canceling a decrease in the blood flow velocity caused by raising in the position of the head. More specifically, the correction information generation unit 104 can generate correction information on the basis of the position change amount, the position characteristic correction parameter set on the basis of the relationship between the position of the blood flow velocity measurement unit and the blood flow velocity fluctuation amount and/or the transient characteristic correction parameter related to transient characteristics of the blood flow velocity. More specific examples of the generated correction information will be described in (2-1) and (2-2) below.

[0097] The correction unit 105 corrects the blood flow velocity measured by the blood flow velocity measurement unit 101 by using the correction information generated by the correction information generation unit 104.

[0098] For example, in a case where the blood flow velocity has increased due to lowering in the position of the head, the correction unit 105 subtracts the increase from the measured blood flow velocity by using the correction information generated by the correction information generation unit 104. Alternatively, in a case where the blood flow velocity has decreased due to raising in the position of the head, the correction unit 105 adds the decrease to the measured blood flow velocity by using the correction information generated by the correction information generation unit 104. As described above, in the present technology, the correction unit 105 can cancel the fluctuation of the blood flow velocity caused by the change in the position of the head by using the correction information. For example, the correction unit 105 can use the correction information to cancel the increase in the blood flow velocity caused by lowering in the position of the head or cancel the decrease in the blood flow velocity caused by raising in the position of the head.

[0099] The position characteristic correction parameter setting unit 106 sets and/or updates the position characteristic correction parameter set on the basis of the relationship between the position of the blood flow velocity measurement unit and the blood flow velocity fluctuation amount.

[0100] The position characteristic correction parameter setting unit 106 can set and/or update the position characteristic correction parameter before, for example, performing correction by the correction unit. The biological information acquisition device 100 may have a predetermined position characteristic correction parameter in advance or may not have the position characteristic correction parameter in advance.

[0101] In a case where the biological information acquisition device 100 has a predetermined position characteristic correction parameter in advance, the position characteristic correction parameter setting unit 106 may update the position characteristic correction parameter before the blood flow velocity is corrected according to the present technology. In a case where the biological information acquisition device 100 has a predetermined position characteristic correction parameter in advance, the position characteristic correction parameter may not be updated. For example, the position characteristic correction parameter set at the time of shipment of the biological information acquisition device 100 may be used as it is, or the position characteristic correction parameter set when a certain user uses the biological information acquisition device 100 for the first time may be used as it is at the next use (when the biological information acquisition device or the blood flow velocity measurement device is mounted after the second time).

[0102] In a case where the biological information acquisition device 100 does not have a position characteristic correction parameter in advance, the position characteristic correction parameter setting unit 106 may set the position characteristic correction parameter before the blood flow velocity is corrected according to the present technology.

[0103] In this way, by setting or updating the position characteristic correction parameter before the blood flow velocity is corrected according to the present technology, the position characteristic correction parameter according to a target (particularly person) whose blood flow is measured by the biological information acquisition device according to the present technology can be set or updated. More accurate correction information can be generated by the set or updated position characteristic correction parameter, and then, more appropriate correction of blood flow velocity can be performed on the basis of the more accurate correction information.

[0104] While the biological information acquisition device according to the present technology is mounted on the target, the position characteristic correction parameter may be updated at predetermined time intervals or for each buffer unit. More specifically, the update may be performed, for example, every 3 minutes to 3 hours, particularly every 5 minutes to 2 hours, and more particularly every 10 minutes to 1 hour. The buffer unit refers to one sample unit of the blood flow velocity measured by the blood flow velocity measurement device. For example, the predetermined number of times of measuring the blood flow velocity can be one unit, or the predetermined time interval in which the blood flow velocity is measured can be one unit. By updating the position characteristic correction parameter at predetermined time intervals or for each buffer unit in this way, for example, in a case where the blood flow velocity is acquired by the biological information acquisition device according to the present technology for a long period of time, a more appropriate position characteristic correction parameter enables more appropriate correction of blood flow velocity.

[0105] The setting and/or update of the position characteristic correction parameter will be described in more detail below in (2-1) or (2-2).

[0106] The transient characteristic correction parameter setting unit 107 sets and/or updates the transient characteristic correction parameter relating to the transient characteristics of the blood flow velocity.

[0107] The transient characteristic correction parameter setting unit 107 can set and/or update the transient characteristic correction parameter, for example, before the blood flow velocity measurement unit performs correction by the correction unit. The biological information acquisition device 100 may have a predetermined transient characteristic correction parameter in advance or may not have the transient characteristic correction parameter in advance.

[0108] In a case where the biological information acquisition device 100 has a predetermined transient characteristic correction parameter in advance, the transient characteristic correction parameter setting unit 107 may update the transient characteristic correction parameter before the blood flow velocity is corrected according to the present technology. In a case where the biological information acquisition device 100 has a predetermined transient characteristic correction parameter in advance, the transient characteristic correction parameter may not be updated. For example, the transient characteristic correction parameter set at the time of shipment of the biological information acquisition device 100 may be used as it is, or the transient characteristic correction parameter set when a certain user uses the biological information acquisition device 100 for the first time may be used as it is at the next use (when the biological information acquisition device or the blood flow velocity measurement device is mounted after the second time).

[0109] In a case where the biological information acquisition device 100 does not have a transient characteristic correction parameter in advance, the transient characteristic correction parameter setting unit 107 may set the transient characteristic correction parameter before the blood flow velocity is corrected according to the present technology.

[0110] In this way, by setting or updating the transient characteristic correction parameter before the blood flow velocity is corrected according to the present technology, the transient characteristic correction parameter according to a target (particularly person) to which the biological information acquisition device according to the present technology is applied can be set or updated. More accurate correction information can be generated by the set or updated transient characteristic correction parameter, and then, more appropriate correction of blood flow velocity can be performed on the basis of the more accurate correction information.

[0111] While the biological information acquisition device according to the present technology is mounted on the target, the transient characteristic correction parameter may be updated at predetermined time intervals or for each buffer unit. More specifically, the update may be performed, for example, every 3 minutes to 3 hours, particularly every 5 minutes to 2 hours, and more particularly every 10 minutes to 1 hour. Therefore, for example, in a case where the blood flow velocity is acquired by the biological information acquisition device according to the present technology for a long period of time, a more appropriate transient characteristic correction parameter enables more appropriate correction of blood flow velocity.

[0112] The setting and/or update of the transient characteristic correction parameter will be described in more detail below in (2-1) or (2-2).

[0113] The output unit 108 can output the measured or corrected blood flow velocity, and output the psychological state or health state of the measurement target determined on the basis of the measured or corrected blood flow velocity, or output a video or a sound based on the measured or corrected blood flow velocity. The output unit 108 can include, for example, a printing device, an image display device, or a sound output device for outputting the blood flow velocity, the psychological state, the health state, the video, or the sound. The video or sound according to the blood flow velocity can be, for example, a video or a sound for notifying the measurement target of a case where the blood flow velocity is out of a predetermined numerical range, or a video or a sound for encouraging the measurement target to take a break.

[0114] The biological information acquisition processing by the biological information acquisition device 100 may be performed as described, for example, in 3. “(2) Example of the third embodiment (biological information acquisition method using position change amount of head)”below.

[0115] (2-1) Correction Information Based on the Amount of Change in Inclination

[0116] According to one embodiment of the present technology, the correction information generation unit 104 can generate the correction information of the blood flow velocity on the basis of the amount of change in the inclination of the blood flow velocity measurement unit. In this embodiment, the inclination can be, for example, an angle projected onto a plane passing the blood flow velocity measurement unit and the center line of the head. The generation of the correction information will be described in more detail below.

[0117] The velocity of blood flow flowing through a blood vessel at a certain position of the head changes as the position of the head changes. The change in the blood flow velocity caused by the change in the position of the head (the increase in the blood flow velocity and the decrease in the blood flow velocity) will be described below with reference to FIG. 2. FIG. 2 is a model diagram for explaining a change in the blood flow velocity.

[0118] As shown on the left side of FIG. 2, the blood flow velocity measurement unit 101 is installed on a frontal head portion (forehead) 211 of a person 210. The blood flow velocity measurement unit 101 includes, for example, an LDF type blood flow velocity measurement device. As shown in FIG. 3, the blood flow velocity measurement unit 101 is arranged at the center of the frontal head portion 211. The blood flow velocity measurement unit 101 can measure the blood flow velocity of the frontal head portion 211 by the LDF method.

[0119] On the left side of FIG. 2, the person 210 faces the front, and the position of the blood flow velocity measurement unit 101 in this state is used as a reference position. In the case shown on the left side of FIG. 2, for example, a blood flow flowing from the heart to the head is defined as V.sub.total, a blood flow velocity in the skin at a certain position on the frontal head portion measured by the blood flow velocity measurement unit 101 is defined as V.sub.1, and a blood flow velocity in the skin at a certain position on the rear head portion is defined as V.sub.2.

[0120] The state in which the person 210 faces downward by an angle .theta. is shown on the right side of FIG. 2. The angle .theta. is the amount of change in the inclination of the blood flow velocity measurement unit 101. As shown in FIG. 4, the angle .theta. is an angle projected onto a plane P passing the blood flow velocity measurement unit 101 and a center line X of the head of the person 210. As shown on the right side of FIG. 2, when the head faces downward by the angle .theta., the blood flow velocity at the certain position of the frontal head portion measured by the blood flow velocity measurement unit 101 increases by a fluctuation amount v (that is V.sub.1+v) and the blood flow velocity in the blood vessel at a certain position on the rear head portion decreases by the fluctuation amount v (that is, V.sub.2-v).

[0121] The fluctuation amount v will be described below using a model related to resistance and gravity acting on a red blood cell of mass m as shown in FIG. 5. In FIG. 5, cv is a resistance acting on a red blood cell RBC, and the resistance is caused by, for example, a blood vessel. In FIG. 5, mg sin .theta. is a force generated by gravity acting on the red blood cell RBC. In the model, the fluctuation amount v is represented by the equation of motion of the following Formula (1).

[ Math . .times. 1 ] m .times. dv dt = - cv + mg .times. .times. sin .times. .times. .theta. ( 1 ) ##EQU00001##

[0122] The above Formula (1) is transformed into the following.

[ Math . .times. 2 ] dv = - c m .times. ( v + mg c .times. sin .times. .times. .theta. ) .times. dt ( 2 ) ##EQU00002##

[0123] Assuming that c/m in Formula (2) is .tau. and mg/c is .alpha., Formula (2) becomes Formula (3) below.

[Math. 3]

dv=-.tau.(v+.alpha.(sin .theta.))dt (3)

[0124] Formula (3) becomes the following Formula (4) by integrating both sides.

[Math. 4]

v=.alpha..times.sin .theta.e.sup.-t/.tau. (4)

[0125] As described above, the fluctuation amount v is represented by Formula (4).

[0126] As described above, according to one embodiment of the present technology, the correction information for canceling the increase in the blood flow velocity caused by lowering in the position of the head may be the fluctuation amount v represented by Formula (4). Furthermore, the correction information for canceling the decrease in the blood flow velocity caused by the raising in the position of the head may also be the fluctuation amount v represented by Formula (4).

[0127] That is, in a case where the position of the blood flow velocity measurement unit 101 becomes low, the increase in the blood flow velocity caused by a change in the position of the head is removed by subtracting the fluctuation amount v represented by Formula (4) from the measured blood flow velocity. In a case where the position of the blood flow velocity measurement unit 101 becomes high, the decrease in the blood flow velocity caused by a change in the position of the head can be compensated by adding the fluctuation amount v represented by Formula (4) to the measured blood flow velocity.

[0128] The symbol a in Formula (4) is called a position characteristic correction parameter. The position characteristic correction parameter may be set or updated on the basis of the relationship between the position of the blood flow velocity measurement unit and the blood flow velocity fluctuation amount. The setting or update can be performed by the position characteristic correction parameter setting unit 106. An example of how to set the position characteristic correction parameter will be described below.

[0129] The blood flow velocity measurement unit 101 is mounted on the forehead of the person. With the blood flow velocity measurement unit 101 mounted, the person changes the position of the head from the reference position to various positions. The various positions can include, for example, one or more, two or more, three or more, or four selected from the position in a case where the person faces downward, the position in a case where the person faces upward, the position in a case where the head is inclined to the right, and the position in a case where the head is inclined to the left. In addition to these positions, for example, the various positions may include the position in a case where the person faces downward and the head is inclined to the right and/or left, the position in a case where the person faces upward and the head is inclined to the right and/or left, and the like.

[0130] At each of the various positions, the blood flow velocity measurement unit 101 measures the blood flow velocity at the forehead, and the detection unit 102 measures the position change amount of the blood flow velocity measurement unit 101. The position characteristic correction parameter setting unit 106 can set and/or update the position characteristic correction parameter on the basis of the blood flow velocity and the position change amount measured at the various positions. That is, the position characteristic correction parameter setting unit 106 can set and/or update the position characteristic correction parameter on the basis of the relationship between the position change amount in a case where the position of the blood flow velocity measurement unit is changed to various different positions from the reference position and the blood flow velocity (particularly, blood flow velocity fluctuation amount) measured at each of the various different positions.

[0131] The blood flow velocity measurement by the blood flow velocity measurement unit 101 may be measured at a point of time when a predetermined time has elapsed after the change in the position of the head to each of the various positions. The blood flow velocity changes with time delay with respect to the change in the position of the head. That is, the change in the blood flow velocity caused by the change in the position of the head has transient characteristics. Therefore, as described above, by measuring the blood flow velocity at a point of time when a predetermined time has elapsed after the change in the position of the head, it is possible to measure a more accurate blood flow velocity after the change in the position of the head. The predetermined time can be, for example, 1 second to 60 seconds, particularly 3 seconds to 40 seconds, and more particularly 5 seconds to 30 seconds.

[0132] Alternatively, the position of the head may be changed so slowly that the transient characteristics are negligible. Blood flow velocity may be measured after the slow change in the position of the head. In a case where the position of the head is changed slowly in this way, the movement of the head does not have to be stopped at a specific position. For example, the head may slowly move for one turn, and blood flow velocity may be measured sequentially during the one turn.

[0133] The symbol .theta. in the Formula (4) is the amount of change in the inclination of the blood flow velocity measurement unit 101 and may be an angle projected onto the plane passing the blood flow velocity measurement unit 101 and the center line of the head of the person 210 as shown in FIG. 4. The symbol .theta. may be measured by the detection unit 102, for example, may be measured by a 3-axis acceleration sensor (not shown) included in the detection unit 102. The detection unit 102 may be arranged at the center of the frontal head portion 211 so as to change the position in the same manner as the position of the blood flow velocity measurement unit 101. For example, by fixing the positional relationship between the detection unit 102 and the blood flow velocity measurement unit 101 in the biological information acquisition device 100, the blood flow velocity measurement unit 101 and the detection unit 102 perform the same positional change. Therefore, the position change amount of the detection unit 102 can be regarded as the position change amount of the blood flow velocity measurement unit 101.

[0134] The symbol .theta. in Formula (4) may be determined using, for example, the following Formula (5) based on an output value of the 3-axis acceleration sensor.

[ Math . .times. 5 ] .theta. = a 1 .times. b 1 + a 2 .times. b 2 + a 3 .times. b 3 a 1 2 + a 2 2 + a 3 2 .times. b 1 2 + b 2 2 + b 3 2 ( 5 ) ##EQU00003##

[0135] In the above Formula (5), a=[a.sub.1, a.sub.2, a.sub.3] is an output value of the 3-axis acceleration sensor when the person 210 is facing the front as shown on the left side of FIG. 2, that is, an output value of the 3-axis acceleration sensor at the reference position. In Formula (5), b=[b.sub.1, b.sub.2, b.sub.3] is an output value of the 3-axis acceleration sensor in a case where the head of the person 210 faces downward by the angle .theta. as shown on the right side of FIG. 2. In the present technology, the angle .theta. may be measured by a gyro sensor.

[0136] For example, at each of the position in a case where the person faces downward, the position in a case where the person faces upward, the position in a case where the head is inclined to the right, the position in a case where the head is inclined to the left, the position in a case where the person faces downward and the head is inclined to the right, the position in a case where the person faces downward and the head is inclined to the left, the position in a case where the person faces upward and the head is inclined to the right, and the position in a case where the person faces upward and the head is inclined to the left, the blood flow velocity fluctuation amount is measured by the blood flow velocity measurement device 201 and the position change amount is measured by the 3-axis acceleration sensor. These measurements at each position may be performed multiple times. The blood flow velocity fluctuation amount and the position change amount at each position are plotted on the vertical axis and the horizontal axis, respectively. The inclination of the straight line obtained by applying the least-squares method to the plotted data may be adopted as position characteristic correction parameter .alpha.. For example, by measurement of the blood flow velocity fluctuation amount and measurement of the position change amount at the various positions, it is possible to obtain plots and a straight line as shown in FIG. 6. In FIG. 6, the vertical axis is the blood flow fluctuation amount v, and the horizontal axis is the position change amount sine.

[0137] The symbol .tau. in the Formula (4) is called a transient characteristic correction parameter. The transient characteristic correction parameter is a parameter related to the transient characteristics of the blood flow velocity. As described above, the blood flow velocity changes with time delay with respect to the change in the position of the head, that is, the change in the blood flow velocity caused by the change in the position of the head has transient characteristics. In order to reflect the transient characteristics in a measurement value of the blood flow velocity, the above-mentioned transient characteristic correction parameter can be used.

[0138] The transient characteristic correction parameter .tau. may be calculated, for example, by fitting a blood flow velocity estimated value estimated by using the position characteristic correction parameter .alpha. to temporal blood flow velocity data temporally measured in the process of changing the position of the blood flow velocity measurement device 201 from the reference position to another position. The fitting may be performed by, for example, a linear fitting or may be performed by a non-linear fitting. For example, the transient characteristic correction parameter setting unit 107 can calculate the transient characteristic correction parameter as described above and set and/or update the parameter.

[0139] (2-2) Correction Information Based on the Amount of Change in Height

[0140] According to another embodiment of the present technology, the correction information generation unit can generate correction information of the blood flow velocity on the basis of the amount of change in the height of the blood flow velocity measurement unit. A more specific example of generating the correction information will be described below.

[0141] The change in the blood flow velocity caused by the change in the position of the head (the increase in the blood flow velocity and the decrease in the blood flow velocity) will be described below with reference to FIG. 7. FIG. 7 is a model diagram for explaining a change in the blood flow velocity. In FIG. 7, the change in the position of the blood flow velocity measurement unit 101 is indicated by using height h instead of the angle .theta. in FIG. 2. That is, the left side of FIG. 7 shows the state where the person 210 is facing the front, that is, the case where the blood flow velocity measurement unit 101 is in the reference position, and the right side of FIG. 7 shows the position of the head 211 lowered by h and the position of the blood flow velocity measurement unit 101 is also lowered by h accordingly.

[0142] On the left side of FIG. 7, the person 210 faces the front, and the position of the blood flow velocity measurement unit 101 in this state is used as a reference position. In the case shown on the left side of FIG. 7, for example, a blood flow flowing from the heart to the head is defined as V.sub.total, a blood flow velocity at a certain position on the frontal head portion measured by the blood flow velocity measurement unit 101 is defined as V.sub.1, and a blood flow velocity in a blood vessel at a certain position on the rear head portion is defined as V.sub.2.

[0143] On the right side of FIG. 7, the height of the frontal head portion 211 of the person 210 is lowered by h, and the position of the blood flow velocity measurement unit 101 is lowered by the height h accordingly. As shown on the right side of FIG. 7, when the position of the head is lowered by the height h, the blood flow velocity at the certain position of the frontal head portion measured by the blood flow velocity measurement unit 101 increases by a fluctuation amount v (that is V.sub.1+v) and the blood flow velocity in the blood vessel at a certain position on the rear head portion decreases by the fluctuation amount v (that is, V.sub.2-v).

[0144] The fluctuation amount v can be represented by the equation of motion using mgh instead of mg sin .theta. in the above Formula (1). The following Formula (6) can be obtained by transforming the equation of motion in a manner similar to the transformation from the above Formula (1) to Formula (4).

[Math. 6]

v=.alpha..times.he.sup.-t/.tau. (6)

[0145] As described above, according to one embodiment of the present technology, the correction information for canceling the increase in the blood flow velocity caused by lowering in the position of the head may be the fluctuation amount v represented by Formula (6). Furthermore, the correction information for canceling the decrease in the blood flow velocity caused by the raising in the position of the head may also be the fluctuation amount v represented by Formula (6).

[0146] That is, in a case where the position of the blood flow velocity measurement unit 101 becomes low, the increase in the blood flow velocity caused by a change in the position of the head is removed by subtracting the fluctuation amount v represented by Formula (6) from the measured blood flow velocity. In a case where the position of the blood flow velocity measurement unit 101 becomes high, the decrease in the blood flow velocity caused by a change in the position of the head can be compensated by adding the fluctuation amount v represented by Formula (6) to the measured blood flow velocity.

[0147] The symbol a in Formula (6) is called a position characteristic correction parameter similar to .alpha. in Formula (4). The position characteristic correction parameter may be set on the basis of the relationship between the position of the blood flow velocity measurement unit and the blood flow velocity fluctuation amount. The position characteristic correction parameter setting unit 106 can set and/or update the position characteristic correction parameter on the basis of the blood flow velocity and the position change amount measured at specific various positions. That is, the position characteristic correction parameter setting unit 106 can set and/or update the position characteristic correction parameter on the basis of the relationship between the position change amount in a case where the position of the blood flow velocity measurement unit is changed to various different positions from the reference position and the blood flow velocity (particularly, blood flow velocity fluctuation amount) measured at each of the various different positions. An example of how to set the position characteristic correction parameter will be described below.

[0148] The blood flow velocity measurement unit 101 is mounted on the forehead of the person. With the blood flow velocity measurement unit 101 mounted, the person changes the position of the head from the reference position to various positions.

[0149] The various positions can include, for example, one or more, two or more, three or more, or four selected from the position in a case where the person faces downward, the position in a case where the person faces upward, the position in a case where the head is inclined to the right, and the position in a case where the head is inclined to the left. In addition to these positions, for example, the various positions may include the position in a case where the person faces downward and the head is inclined to the right and/or left, the position in a case where the person faces upward and the head is inclined to the right and/or left, and the like.

[0150] At each of the various positions, the blood flow velocity measurement unit 101 measures the blood flow velocity at the forehead, and the detection unit 102 detects the position change amount of the blood flow velocity measurement unit 101.

[0151] The blood flow velocity measurement by the blood flow velocity measurement unit 101 may be measured at a point of time when a predetermined time has elapsed after the change in the position of the head to each of the various positions. Therefore, as described above, it is possible to eliminate the transient characteristics and measure the more accurate blood flow velocity after the change in the head position. The predetermined time can be, for example, 1 second to 60 seconds, particularly 3 seconds to 40 seconds, and more particularly 5 seconds to 30 seconds.

[0152] Alternatively, the position of the head may be changed so slowly that the transient characteristics are negligible. Blood flow velocity may be measured after the slow change in the position of the head. In a case where the position of the head is changed slowly in this way, the movement of the head does not have to be stopped at a specific position.

[0153] The symbol h in Formula (6) can be the amount of change in the height of the blood flow velocity measurement unit 101. The symbol h may be measured by the detection unit 102, for example, by a barometric pressure sensor (not shown) included in the detection unit 102. The detection unit 102 may be arranged at the center of the frontal head portion 211 so as to change the position in the same manner as the position of the blood flow velocity measurement unit 101. For example, by fixing the positional relationship between the detection unit 102 and the blood flow velocity measurement unit 101 in the biological information acquisition device 100, the blood flow velocity measurement unit 101 and the detection unit 102 perform the same positional change. Therefore, the position change amount of the detection unit 102 can be regarded as the position change amount of the blood flow velocity measurement unit 101.

[0154] The symbol h in Formula (6) may be determined by, for example, an acceleration sensor, a gyro sensor, or a barometric pressure sensor. For example, for symbol h in

[0155] Formula (6), the amount of change in height h may be determined on the basis of the change in barometric pressure measured by the barometric pressure sensor.

[0156] For example, in each of cases where the head is at various heights, the blood flow velocity measurement unit 101 measures the blood flow velocity fluctuation amount and the detection unit 102 measures the position change amount. These measurements at each height may be performed multiple times. The blood flow velocity fluctuation amount and the position change amount at each height are plotted on the vertical axis and the horizontal axis, respectively. The inclination of the straight line obtained by applying the least-squares method to the plotted data may be adopted as position characteristic correction parameter .alpha..

[0157] The symbol .tau. in Formula (6) is called a transient characteristic correction parameter similar to .tau. in Formula (4). The transient characteristic correction parameter is a parameter related to the transient characteristics of the blood flow velocity. As mentioned above, the change in the blood flow velocity caused by the change in the position of the head has transient characteristics. In order to reflect the transient characteristics in a measurement value of the blood flow velocity, the above-mentioned transient characteristic correction parameter can be used.

[0158] The transient characteristic correction parameter .tau. may be calculated, for example, by fitting a blood flow velocity estimated value estimated by using the position characteristic correction parameter .alpha. to temporal blood flow velocity data temporally measured in the process of changing the position of the blood flow velocity measurement unit 101 from the reference position to another position. The fitting may be performed by, for example, a linear fitting or may be performed by a non-linear fitting. For example, the transient characteristic correction parameter setting unit 107 can calculate the transient characteristic correction parameter as described above and set and/or update the parameter.

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