Biological information measuring device including light source, light detector, and control circuit

Abstract

A biological information measuring device according to an aspect of the present disclosure includes: a light source that, in operation, emits irradiation light for irradiating a test portion of a subject; a light detector that, in operation, detects light from the subject and outputs an electrical signal corresponding to the light; and a control circuit that, in operation, determines a power of the irradiation light emitted by the light source, and that, in operation, measures biological information related to a blood flow at the test portion based on the electrical signal. The control circuit, in operation, detects a distance between the light source and the test portion based on the electrical signal, and determines the power of the irradiation light such that the power of the irradiation light is increased as the distance increases.

What is claimed is: 
     
         1 . A device comprising:
 a light source that emits pulsed light to a subject;   at least one detector that detects light, the light including returned pulsed light which is returned from the subject due to emission of the pulsed light; and   a circuit that causes the at least one detector to detect the returned pulsed light, the returned pulsed light including internal scattering component which is scattered inside the subject, wherein   the circuit causes the at least one detector to detect the internal scattering component by controlling a shutter timing of the at least one detector, and   the circuit generates biological information indicating pulse wave of the subject based on the internal scattering component.   
     
     
         2 . The device according to  claim 1 , wherein:
 the circuit estimates a distance between the light source and the subject based on the light detected by the at least one detector; and   the circuit determines a power of the pulsed light emitted by the light source based on the distance.   
     
     
         3 . The device according to  claim 2 , wherein the circuit estimates the distance based on the returned pulsed light. 
     
     
         4 . The device according to  claim 2 , wherein:
 the at least one detector includes a first detector and a second detector;   the circuit generates the biological information based on a first signal from the first detector; and   the circuit estimates the distance based on a second signal from the second detector.   
     
     
         5 . The device according to  claim 4 , wherein:
 the first detector detects the returned pulsed light; and   the second detector detects visible light from the subject.   
     
     
         6 . The device according to  claim 1 , wherein:
 the light source emits first pulsed light to a first portion of the subject and second pulsed light to a second portion of the subject;   the circuit causes the at least one detector to detect first internal scattering component which is scattered inside the first portion from first returned pulsed light, the first returned pulsed light being returned from the first portion to the at least one detector due to emission of the first pulsed light;   the circuit causes the at least one detector to detect second internal scattering component which is scattered inside the second portion from second returned pulsed light, the second returned pulsed light being returned from the second portion to the at least one detector due to emission of the second pulsed light;   the circuit generates first biological information indicating pulse wave of the first portion based on the first internal scattering component and second biological information indicating pulse wave of the second portion based on the second internal scattering component; and   the circuit generates information indicating a blood pressure of the subject based on the first biological information and the second biological information.   
     
     
         7 . The device according to  claim 2 , wherein:
 the light source is stationary during a testing process; and   the distance between the light source and the subject is variable during the testing process due to movement of the subject.   
     
     
         8 . A method comprising:
 emitting pulsed light to a subject;   detecting, by controlling a timing of detection, internal scattering component which is included in returned pulsed light and scattered inside the subject, the returned pulsed light being returned from the subject due to emission of the pulsed light; and   obtaining biological information indicating pulse wave of the subject based on the internal scattering component.   
     
     
         9 . A non-transitory computer-readable recording medium storing a program which performs a method when the program is executed by a computer, the method comprising:
 causing a light source to emit pulsed light to a subject;   causes a detector to detect, by controlling a shutter timing of the detector, internal scattering component which is included in returned pulsed light and scattered inside the subject, the returned pulsed light being returned from the subject due to emission of the pulsed light; and   generating biological information indicating pulse wave of the subject based on the internal scattering component.