JP7567233B2 - Brain function detection device - Google Patents

Description

This disclosure relates to a brain function detection device.

The technology disclosed in Patent Document 1 detects brain function in the head by diffusing and reflecting a light beam generated by a light source unit on the head of a person to be detected and receiving the light beam with a detection unit.

JP 2015-134157 A

Now, the presence of hair on the head of the person to be detected attenuates the light beam. Therefore, in the technology disclosed in Patent Document 1, depending on the state of the hair of the person to be detected, the amount of light beam received by the light receiving unit may be insufficient for detecting brain function, which may lead to detection failure.

The objective of this disclosure is to provide a brain function detection device that eliminates detection failures.

The technical means of the present disclosure for solving the problems will be explained below. Note that the claims and the reference characters in parentheses in this section indicate the corresponding relationship with the specific means described in the embodiments described in detail later, and do not limit the technical scope of the present disclosure.

A first aspect of the present disclosure is
an illumination unit (10) having a light source section (12) that generates a beam of light that can be diffusely reflected by a head (2a) of a person to be detected (2) that is located in an illumination area (3), and that emits the beam of light generated by the light source section from the front toward the illumination area;
a detection unit (20) having a plurality of light receiving sections (222a, 222b, 222c) for receiving the light beam diffusely reflected from the irradiation area, and detecting brain function in the head based on the light beam received by the light receiving sections;
If a vertical plane (Sv) including the optical axis (Al) of the beam light emitted from the irradiation unit and extending above and below the irradiation area and a horizontal axis (Lh) perpendicular to the vertical plane are hypothetically defined,
The light receiving units are arranged in a superimposed manner within a specific angle range (Rθ) of 45 degrees above and below the horizontal axis, with the intersection (Ic) of the optical axis included in the vertical plane and the horizontal axis as the center,
the detection unit further has a control unit which calculates a hair ratio (Ph) which is a ratio of a total area of hair (2c) on the head within the spot diameter to an entire area of the spot diameter (φ) in an irradiation region of the beam light, and switches an effective light receiving unit (522) which receives the beam light to be detected for brain function from among a plurality of light receiving units so as to maximize light receiving efficiency at the calculated hair ratio ;
The irradiation unit further includes an emission section that variably adjusts a spot diameter in an irradiation area of the emitted beam light in accordance with a proportion of hair,
The emission unit adjusts and maintains the spot diameter when the hair ratio is equal to or smaller than a threshold value, and adjusts and enlarges the spot diameter when the hair ratio exceeds the threshold value.

In the detection unit of the first embodiment, the light receiving section is superimposed in a specific angle range of 45 degrees above and below the horizontal axis, centered on the intersection with the horizontal axis that is perpendicular to the vertical plane containing the optical axis of the beam light emitted from the irradiation unit in front of the irradiation area. With this, in the range in which the head of the person to be detected located in the irradiation area is normally tilted from the normal position, the beam light diffusely reflected from the head passes through the hair and is easily received by the light receiving section superimposed in the specific angle range. This makes it possible to eliminate a situation in which the amount of beam light received by the light receiving section is insufficient, leading to poor detection of brain function.

A second aspect of the present disclosure is
an illumination unit (10) having a light source section (12) that generates a beam of light that can be diffusely reflected by a head (2a) of a person to be detected (2) that is located in an illumination area (3), and that emits the beam of light generated by the light source section from the front toward the illumination area;
a detection unit (20) having a light receiving section (22) for receiving a light beam diffusely reflected from an irradiation area and detecting a brain function in the head based on the light beam received by the light receiving section;
The irradiation unit is a brain function detection device further having an emission section (314, 414) that variably adjusts the spot diameter (φ) of the emitted beam light in the irradiation area.

In the second embodiment of the irradiation unit, the emission section variably adjusts the spot diameter in the irradiation area of the beam of light emitted from the front. This makes it possible to set a spot diameter that makes it easier for the beam of light diffusely reflected by the head of the subject located in the irradiation area to be received by the light receiving section. This makes it possible to eliminate situations in which the amount of beam light received by the light receiving section is insufficient, leading to poor detection of brain function.

A third aspect of the present disclosure is
an illumination unit (10) having a light source section (12) that generates a beam of light that can be diffusely reflected by a head (2a) of a person to be detected (2) that is located in an illumination area (3), and that emits the beam of light generated by the light source section from the front toward the illumination area;
a detection unit (20) having a plurality of light receiving sections (522a, 522b, 522c) for receiving the light beam diffusely reflected from the irradiation area, and detecting brain function in the head based on the light beam received by the light receiving sections;
The detection unit is a brain function detection device which further has a control unit (524) which switches an effective light receiving unit (522) which receives the beam light to be detected as the subject of brain function detection from among a plurality of light receiving units based on a hair ratio (Ph) which is the ratio of the total area of the hair (2c) on the head within the spot diameter to the total area of the spot diameter (φ) in the irradiation region of the beam light.

In the detection unit of the first and third aspects, the control unit switches the effective light receiving unit of the light beam to be detected as the brain function detection target from among the multiple light receiving units. At this time, the switching is based on the hair ratio of the total area of the hair on the head within the spot diameter of the light beam emitted from the front to the total area of the spot diameter in the irradiation area of the light beam emitted from the front. This makes it possible to select the effective light receiving unit that is likely to receive the light beam diffusely reflected on the head of the subject located in the irradiation area according to the hair condition of the head. Therefore, it is possible to eliminate the situation in which the detection of brain function is poor due to other light receiving units that receive an insufficient amount of light beam.

A fourth aspect of the present disclosure is
an illumination unit (10) having a light source section (12) that generates a beam of light that can be diffusely reflected by a head (2a) of a person to be detected (2) that is located in an illumination area (3), and that emits the beam of light generated by the light source section from the front toward the illumination area;
a detection unit (20) having a plurality of light receiving sections (522a, 522b, 522c) for receiving the light beam diffusely reflected from the irradiation area, and detecting brain function in the head based on the light beam received by the light receiving sections;
The irradiation unit further includes an emission section (614) that variably adjusts the optical axis direction (Dl) of the emitted beam light,
The detection unit is a brain function detection device that further includes a control unit (624) that switches between effective light receiving units (522) that receive the beam light that is the subject of brain function detection, from among a plurality of light receiving units, in line with the optical axis direction.

In the detection unit of the fourth aspect, the control unit switches the effective light receiving unit for the light beam that is the subject of brain function detection from among multiple light receiving units in accordance with the optical axis direction of the light beam that is emitted from the front by the emission unit in the irradiation unit and variably adjusted. This makes it possible to select an effective light receiving unit that is more likely to receive the diffusely reflected light beam, depending on the compatibility between the state of the hair on the head of the subject located in the irradiation area and the optical axis direction. This makes it possible to eliminate situations in which poor detection of brain function occurs due to other light receiving units receiving an insufficient amount of light beam.

1 is a side view showing the overall configuration of a brain function detecting device according to a first embodiment. 1 is a side view showing an example of mounting the brain function detecting device according to a first embodiment on a vehicle. FIG. 4 is a graph for explaining characteristics of the brain function detecting device according to the first embodiment. 4 is a graph for explaining characteristics of the brain function detecting device according to the first embodiment. 4 is a graph for explaining characteristics of the brain function detecting device according to the first embodiment. 4 is a graph for explaining characteristics of the brain function detecting device according to the first embodiment. FIG. 7 is a view taken along line VII-VII in FIG. FIG. 7 is a view taken along line VII-VII of a modified example of the embodiment shown in FIG. FIG. 7 is a view taken along line VII-VII of a modified example of the embodiment shown in FIG. FIG. 7 is a view taken along line VII-VII of a modified example of the embodiment shown in FIG. 2 is a schematic diagram for explaining a detailed configuration of the brain function detecting device according to the first embodiment. FIG. 2 is a schematic diagram for explaining a detailed configuration of the brain function detecting device according to the first embodiment. FIG. FIG. 11 is a side view showing the overall configuration of a brain function detecting device according to a second embodiment. This is a view taken along line XIV-XIV in Figure 13. FIG. 11 is a side view showing the overall configuration of a brain function detecting device according to a third embodiment. 13 is a schematic diagram for explaining the operation of the brain function detecting device according to the third embodiment. FIG. 13 is a graph for explaining characteristics of the brain function detecting device according to the third embodiment. FIG. 13 is a side view showing the overall configuration of a brain function detecting device according to a fourth embodiment. FIG. 13 is a side view showing the overall configuration of a brain function detecting device according to a fifth embodiment. This is a view taken along the line XX-XX in Figure 19. FIG. 21 is a schematic diagram for explaining the characteristics of the brain function detecting device according to the fifth embodiment, corresponding to FIG. 20 . FIG. 13 is a side view showing the overall configuration of a brain function detecting device according to a sixth embodiment. FIG. 7 is a view taken along line VII-VII of a modified example of the embodiment shown in FIG. FIG. 7 is a view taken along line VII-VII of a modified example of the embodiment shown in FIG.

Below, several embodiments are described with reference to the drawings. Note that in each embodiment, corresponding components are given the same reference numerals, and duplicated descriptions may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of the other embodiment described above may be applied to the other portions of the configuration. In addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments may be partially combined together even if not explicitly stated, as long as there is no particular problem with the combination.

First Embodiment
1 detects brain functions of a subject 2. The brain function detection device 1 detects cerebral blood flow corresponding to brain activity in the cerebral cortex in a head 2a of the subject 2 in a non-contact manner by near-infrared spectroscopy known as NIRS. For this purpose, the brain function detection device 1 includes an irradiation unit 10 and a detection unit 20.

The irradiation unit 10 has a light source section 12 and an emission section 14. The light source section 12 is a laser element or a light-emitting diode element that generates a beam of light that can be diffusely reflected by the head 2a of the person to be detected 2. In particular, the light source section 12 generates near-infrared light of a single wavelength or multiple wavelengths in the range of 650 to 950 nm, for example, as a beam of light. Here, the light source section 12 that generates beams of light of multiple wavelengths may be composed of a wavelength-variable light source, or may be composed of multiple light sources of different wavelengths.

The emission unit 14 is an optical system that emits the beam light generated by the light source unit 12 from the front toward the irradiation area 3. In particular, the emission unit 14 is configured by a combination of, for example, lenses and mirrors that collimate and align the beam light. Here, the head 2a of the subject 2 is located in the irradiation area 3 when detecting brain function. For example, when the brain function detection device 1 is mounted on a vehicle 4 as shown in FIG. 2, the position of the irradiation area 3 that matches the position of the head 2a is set with respect to the seat 4a on which the subject 2 is seated.

1 and 2, the emission unit 14 emits a directional beam of light from the front of the irradiation area 3, aiming at a position of the head 2a of the subject 2 in the irradiation area 3 corresponding to the surface of the forehead 2b. At this time, the emission unit 14 of the first embodiment fixes the optical axis direction Dl (i.e., emission direction) of the emitted beam of light, for example, in the front-rear direction of the horizontal direction in the vehicle 4 on the horizontal plane HP (see FIG. 2). Alternatively, the emission unit 14 fixes the optical axis direction Dl of the beam of light, for example, in the horizontal direction in the vehicle 4 on the horizontal plane HP, obliquely upward or downward inclined with respect to the front-rear direction. Furthermore, the emission unit 14 also fixes the spot diameter φ of the beam of light at a position of the head 2a of the subject 2 in the irradiation area 3 corresponding to the surface of the forehead 2b. Here, the diameter of the beam, which is the so-called Gaussian spot diameter φ (i.e., 1/ ^e2 width of the maximum intensity), can be appropriately set as shown in FIGS. 3 to 6, taking into consideration, for example, the thickness of the hair 2c that overlaps the forehead 2b of the head 2a, but is preferably set to 10 mm or more, which is greater than the values in FIGS. 5 and 6.

As shown in FIG. 1, the detection unit 20 has a light receiving section 22 and a control section 24. The light receiving section 22 is a semiconductor sensor element that receives, on a light receiving surface, a light beam that is diffusely reflected by the head 2a of the person to be detected 2 located in the irradiation area 3 from the irradiation area 3. The light receiving section 22 outputs a signal that indicates the amount of received light beam according to the power of the light beam that is diffusely reflected within the head 2a in the irradiation area 3 and then reaches the light receiving section 22.

The light receiving unit 22 in the first embodiment is arranged singly, overlapping the specific angle range Rθ shown in Figs. 1, 3 to 7. As shown in Figs. 1, 2, and 7, a vertical plane Sv is virtually defined that includes the optical axis Al of the beam light emitted from the emission unit 14 of the irradiation unit 10 and extends above and below the irradiation area 3. For example, the vertical plane Sv in the vehicle 4 on the horizontal plane HP (see Fig. 2) actually coincides with the vertical plane. Furthermore, in the first embodiment, a horizontal axis Lh that is perpendicular to the vertical plane Sv and runs along the horizontal direction of the irradiation area 3 is virtually defined. For example, the horizontal axis Lh in the vehicle 4 on the horizontal plane HP actually coincides with the horizontal axis. Under these virtual definitions, in the first embodiment, a specific angle range Rθ is defined on both the left and right sides of the vertical plane Sv, in particular, within an angle range of 45 degrees above and below the horizontal axis Lh, with the intersection Ic of the optical axis Al and the horizontal axis Lh as the center.

Therefore, a single light receiving unit 22 is arranged at a position where at least a portion of the light receiving surface overlaps with the specific angle range Rθ. In particular, Figures 1 and 7 show a representative example of a detection unit 20 in which the center of the light receiving surface of the light receiving unit 22 is arranged at a position 45 degrees below the horizontal axis Lh, to the left of the vertical plane Sv when viewed from the subject 2 whose head 2a is located in the irradiation area 3 (i.e., when viewed in the opposite direction to the optical axis direction Dl). Of course, arrangements other than this example may be adopted as long as they satisfy the above-mentioned regulations.

For example, as shown in FIG. 8, the center of the light receiving surface of the light receiving unit 22 may be located at a position 45 degrees above the horizontal axis Lh on the left side of the vertical plane Sv when viewed from the person to be detected 2 within the specific angle range Rθ, or at a position 45 degrees above or below the horizontal axis Lh on the right side of the vertical plane Sv when viewed from the person to be detected 2 (the figure shows an example of 45 degrees to the right and above). Alternatively, as shown in FIG. 9, the center of the light receiving surface of the light receiving unit 22 may be located at a position more than 0 degrees and less than 45 degrees above or below the horizontal axis Lh on the left or right side of the vertical plane Sv when viewed from the person to be detected 2 within the specific angle range Rθ (the figure shows an example of 30 degrees to the left and below). Alternatively, as shown in FIG. 10, the center of the light receiving surface of the light receiving unit 22 may be located at a position 0 degrees from the horizontal axis Lh, i.e., on the horizontal axis Lh, to the left or right of the vertical plane Sv when viewed from the subject 2 within the specific angle range Rθ (the figure shows an example of the center being on the right and at 0 degrees).

Furthermore, in the first embodiment, as shown in Figures 1 and 7 to 10, an orthogonal plane So perpendicular to the optical axis Al of the beam light emitted from the emission section 14 of the irradiation unit 10 is virtually defined. Under this virtual definition and the virtual definition described above, the specific angle range Rθ in which the center of the light receiving surface of the light receiving section 22 is located is defined on the orthogonal plane So passing through the emission section 14 of the irradiation unit 10. As a result, the single light receiving section 22 is superimposed on the specific angle range Rθ around the emission section 14.

Now, when the head 2a of the subject 2 is in the normal position in the irradiation area 3, the hair flow of the hair 2c of the head 2a that overlaps the forehead 2b tends to be in the vertical direction, as shown in FIG. 11. On the other hand, when the head 2a located in the irradiation area 3 is tilted from the normal position, the hair flow of the hair 2c of the head 2a that overlaps the forehead 2b tends to be in the vertical direction to substantially the same extent as the head 2a, as shown in FIG. 12. In either case, the light receiving unit, which is assumed to be located in the direction of the hair flow starting from the optical axis Al, receives a drastic reduction in the amount of light beam that is blocked and attenuated by the hair 2c. Here, the angle range in which the head 2a is usually tilted is less than 45 degrees to the left and right of the vertical direction. Therefore, the specific angle range Rθ is specified as described above so that the light receiving unit 22 is avoided from being placed in the hair flow direction in the range in which the head 2a is usually tilted starting from the optical axis Al.

The control unit 24 shown in FIG. 1 is mainly composed of a microcomputer. The control unit 24 is electrically connected to the light source unit 12 of the irradiation unit 10 and the light receiving unit 22 of the detection unit 20. The control unit 24 controls the generation of the beam light by the light source unit 12 and the reception of the beam light by the light receiving unit 22 in response to the generation of the beam light. The control unit 24 detects cerebral blood flow as a brain function based on the amount of beam light received by the light receiving unit 22. The control unit 24 may output the detection results or the state of brain activity determined from the detection results to a display device (not shown) inside or outside the brain function detection device 1.

(Action and Effect)
The effects of the first embodiment described above will be described below.

In the detection unit 20 of the first embodiment, the light receiving unit 22 is superimposed in a specific angle range Rθ of 45 degrees above and below the horizontal axis Lh, centered on the intersection Ic with the horizontal axis Lh that is perpendicular to the vertical plane Sv containing the optical axis Al of the beam light emitted from the irradiation unit 10 in front of the irradiation area 3. According to this, in the range in which the head 2a of the subject 2 located in the irradiation area 3 is normally tilted from the normal position, the beam light diffusely reflected by the head 2a passes through the hair 2c and is easily received by the light receiving unit 22 superimposed in the specific angle range Rθ. Therefore, it is possible to eliminate a situation in which the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

The light receiving unit 22 of the first embodiment is superimposed in a specific angle range Rθ of 45 degrees above and below the horizontal axis Lh, centered on the intersection Ic between the optical axis Al of the light beam emitted from the irradiation unit 10 and the horizontal axis Lh. With this, in the range in which the head 2a of the person to be detected 2 is normally tilted from the normal position, the light beam diffusely reflected by the head 2a passes through the hair 2c and is easily received by the light receiving unit 22 around the optical axis Al. This makes it possible to eliminate, with a simple configuration, a situation in which the amount of light beam received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

The light receiving unit 22 of the first embodiment is superimposed on an orthogonal plane So that is perpendicular to the optical axis Al of the beam light emitted from the irradiation unit 10 and passes through the irradiation unit 10, in a specific angle range Rθ centered on Ic between the optical axis Al and the horizontal axis line Lh. With this, in the range in which the head 2a of the subject 2 is normally tilted from the normal position, the beam light diffusely reflected by the head 2a passes through the hair 2c and is easily received by the light receiving unit 22 around the irradiation unit 10. With this, it is possible to eliminate the situation in which the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function, with a simple and compact configuration.

According to the first embodiment, in the range in which the head 2a of the subject 2 is normally tilted from the normal position, the beam light diffusely reflected by the head 2a passes through the hair 2c, and the amount of light received by the single light receiving unit 22 arranged superimposedly in the specific angle range Rθ is likely to increase. This makes it possible to eliminate, with a simple and compact configuration, a situation in which the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

In the first embodiment, the irradiation unit 10 sets the spot diameter φ of the emitted beam light in the irradiation area 3 to 10 mm or more. With this, the beam light with a large spot diameter φ is diffusely reflected on the head 2a of the person to be detected 2, making it easier for the beam light to pass between the hair 2c and therefore easier to be received by the light receiving unit 22. This makes it possible to increase reliability in resolving situations where the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

Second Embodiment
The second embodiment is a modified example of the first embodiment. As shown in Figures 13 and 14, in the second embodiment, a plurality of light receiving sections 222a, 222b, and 222c are arranged at positions where at least a part of the light receiving surface overlaps with the specific angle range Rθ. Here, the specific angle range Rθ in the second embodiment is also defined on an orthogonal plane So passing through the emission section 14 of the irradiation unit 10, within an angular range of 45 degrees above and below the horizontal axis Lh, centered on the intersection Ic of the optical axis Al and the horizontal axis Lh on the vertical plane Sv.

The specific angle range Rθ in Figures 13 and 14 in particular representatively shows an example in which the centers of the light receiving surfaces of the light receiving units 222a, 222b, and 222c are located at positions 45 degrees above, 45 degrees below, and 0 degrees below the horizontal axis Lh to the left of the vertical plane Sv when viewed from the subject 2 whose head 2a is located in the irradiation area 3. Of course, any arrangement other than this example may be adopted as long as it satisfies the above-mentioned regulations.

In this second embodiment, the control unit 224 individually controls the generation of the beam light by the light source unit 12 and the reception of the beam light by each of the light receiving units 222a, 222b, and 222c in response to the generation of the beam light. The control unit 224 detects cerebral blood flow as a brain function based on the amount of beam light received by each of the light receiving units 222a, 222b, and 222c.

(Action and Effect)
The effects of the second embodiment, which are different from those of the first embodiment, will be described below.

According to the second embodiment, in the range in which the head 2a of the subject 2 is normally tilted from the normal position, the beam light diffusely reflected by the head 2a passes through the hair 2c, which tends to increase the amount of light received by the multiple light receiving units 222a, 222b, and 222c arranged in a superimposed manner in the specific angle range Rθ. This makes it possible to increase the reliability of eliminating situations that lead to poor detection of brain function.

Third Embodiment
The third embodiment is a modified example of the first embodiment. The emission unit 314 of the third embodiment shown in Fig. 15 variably adjusts the spot diameter φ in the irradiation area 3 of the beam light emitted from the front with the optical axis direction Dl fixed, under the control of the control unit 324. For this purpose, the control unit 324 of the third embodiment calculates the hair ratio Ph that is adjusted to the adjustment of the spot diameter φ shown in Fig. 16. Here, the hair ratio Ph is the ratio of the total area of the hair 2c on the forehead 2b of the head 2a of the detection subject 2 located in the irradiation area 3 within the spot diameter φ of the beam light to the total area of the spot diameter φ of the beam light in the irradiation area 3 (hereinafter referred to as the spot area).

The control unit 324 may obtain a photographed image of the irradiation region 3 photographed from the front by an internal or external imaging device (not shown) of the brain function detection device 1. In this case, the control unit 324 estimates the total area assumed to be occupied by the hair 2c within the spot diameter φ of the initial condition from image processing of the photographed image, and calculates the hair ratio Ph for the spot area within the spot diameter φ of the initial condition. Alternatively, the control unit 324 may cause the light receiving unit 22 to receive the diffuse reflection of the beam light emitted from the emission unit 314 with the spot diameter φ of the initial condition. In this case, the control unit 324 calculates the total area actually occupied by the hair 2c within the spot diameter φ of the initial condition from analysis processing of the amount of beam light received by the light receiving unit 22, and calculates the hair ratio Ph for the spot area within the spot diameter φ of the initial condition.

In either case, the control unit 324 initially sets the initial spot diameter φ to 10 mm as shown in FIG. 17 in order to execute image processing of the captured image or analysis of the amount of received light as an initial operation before entering the actual detection operation of brain function. Here, FIG. 17 shows that when the thickness of the hair 2c is 1 mm, if the hair ratio Ph corresponding to the initial spot diameter φ is 0.4 or less, the light receiving efficiency of the light receiving unit 22 exceeds 50%.

Therefore, in particular, in the third embodiment, when the hair ratio Ph calculated for the spot diameter φ of the initial condition is equal to or less than a threshold value, for example 0.4, the control unit 324 causes the emission unit 314 in this detection operation to adjust the spot diameter φ to maintain the initial setting. On the other hand, when the hair ratio Ph exceeds the threshold value, the control unit 324 causes the emission unit 314 in this detection operation to adjust the spot diameter φ to an enlarged size exceeding the initial setting.

The control unit 324 of this detection operation controls the generation of the beam light by the light source unit 12, the adjustment of the spot diameter φ by the emission unit 314, and the reception of the beam light by the light receiving unit 22 in a specific angle range Rθ according to these. The control unit 324 detects cerebral blood flow as a brain function based on the amount of beam light received by the light receiving unit 22 with a light receiving efficiency of over 50%.

(Action and Effect)
The effects of the third embodiment, which are different from those of the first embodiment, will be described below.

In the irradiation unit 10 of the third embodiment, the emitter 314 variably adjusts the spot diameter φ in the irradiation area 3 of the beam light emitted from the front. This makes it possible to set the spot diameter φ at which the beam light diffusely reflected on the head 2a of the subject 2 located in the irradiation area 3 is easily received by the light receiver 22. This makes it possible to eliminate a situation in which the amount of beam light received by the light receiver 22 is insufficient, leading to poor detection of brain function.

The emission unit 314 of the third embodiment variably adjusts the spot diameter φ according to the hair proportion Ph of the total area of the hair 2c on the head 2a within the spot diameter φ relative to the total spot area of the entire spot diameter φ in the irradiation region 3. This allows the spot diameter φ at which the beam light is easily received by the light receiving unit 22 to be set according to the hair condition of the head 2a. This makes it possible to increase reliability in resolving situations where the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

The emission unit 314 of the third embodiment may variably adjust the spot diameter φ based on the hair ratio Ph calculated from the captured image of the irradiation area 3. This allows the spot diameter φ to be accurately set from the actual captured image so that the amount of light received by the light receiving unit 22 increases according to the state of the hair on the head 2a. This makes it possible to ensure high reliability in resolving situations where the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

The emission unit 314 of the third embodiment may variably adjust the spot diameter φ based on the hair ratio Ph calculated from the amount of beam light received by the light receiving unit 22. This allows the spot diameter φ to be accurately set from the actual light receiving result so that the amount of light received by the light receiving unit 22 increases according to the hair condition of the head 2a. Therefore, it is possible to ensure high reliability in resolving situations where the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

(Fourth embodiment)
The fourth embodiment is a modification of the third embodiment. As shown in Fig. 18, the emission unit 414 of the fourth embodiment performs continuous or discrete variable adjustment of the spot diameter φ in an initial operation under the control of the control unit 324. To this end, the control unit 424 for the initial operation calculates the hair ratio Ph each time the spot diameter φ is changed by the emission unit 414 from the captured image of the irradiation area 3 or the amount of beam light received by the light receiving unit 22 as an initial operation according to the third embodiment.

The control unit 424 in the initial operation selects the effective spot diameter φe that maximizes the light receiving efficiency for the calculated hair proportion Ph. Furthermore, the control unit 424 in the main detection operation controls the generation of the beam light by the light source unit 12, the adjustment of the effective spot diameter φe by the emission unit 414, and the reception of the beam light by the light receiving unit 22 in the specific angle range Rθ corresponding to these. The control unit 424 detects cerebral blood flow as a brain function based on the amount of beam light received by the light receiving unit 22 at the maximum light receiving efficiency.

(Action and Effect)
The effects of the fourth embodiment, which are different from those of the first and third embodiments, will be described below.

The emission unit 414 of the fourth embodiment variably adjusts the spot diameter φ in accordance with the change in the amount of beam light received by the light receiving unit 22, which corresponds to the dimensional change in the spot diameter φ. This allows the effective spot diameter φe to be accurately set so that the amount of beam light diffusely reflected by the head 2a of the person to be detected 2 and received by the light receiving unit 22 increases according to the hair condition of the head 2a. Therefore, it is possible to ensure high reliability in resolving situations in which the amount of beam light received by the light receiving unit 22 is insufficient, leading to poor detection of brain function.

Fifth Embodiment
The fifth embodiment is a modified example of the third embodiment. As shown in Figures 19 and 20, in the fifth embodiment, the requirement of the specific angle range Rθ is removed, and a plurality of light receiving units 522a, 522b, and 522c are arranged. Specifically, in the fifth embodiment, the light receiving units 522a, 522b, and 522c are arranged on an orthogonal plane So passing through the emission unit 14 of the irradiation unit 10, within an arbitrary angle range from the horizontal axis Lh, centered on the intersection Ic of the optical axis Al and the horizontal axis Lh in the vertical plane Sv.

The specific angle range Rθ in particular in Figures 19 and 20 representatively shows an example in which the centers of the light receiving surfaces of the light receiving units 522a, 522b, and 522c are located at 0 degrees, 45 degrees below, and 90 degrees below the horizontal axis Lh, at least to the left of the vertical plane Sv when viewed from the subject 2 whose head 2a is located in the irradiation area 3. Of course, arrangements other than this example may be adopted.

In the fifth embodiment, the emission unit 14 of the first embodiment, which fixes the optical axis direction Dl and the spot diameter φ, is used instead of the emission unit 314 of the third embodiment, which fixes the optical axis direction Dl and variably adjusts the spot diameter φ. Also, in the fifth embodiment, the control unit 524 of the third embodiment, which controls the variable adjustment of the spot diameter φ, is used instead of the control unit 324 of the third embodiment, which controls the variable adjustment of the spot diameter φ.

Specifically, the control unit 524 of the fifth embodiment calculates the hair ratio Ph for a fixed spot diameter φ from the captured image of the irradiation area 3 or the amount of light beam received by each light receiving unit 522a, 522b, 522c as an initial operation conforming to the third embodiment. Therefore, the control unit 524 of this detection operation in particular selects the effective light receiving unit 522 with the maximum light receiving efficiency for the calculated hair ratio Ph from the light receiving units 522a, 522b, 522c, as shown in FIG. 21 for example. Furthermore, the control unit 524 of this detection operation controls the generation of the beam light by the light source unit 12 and the reception of the beam light by the effective light receiving unit 522 corresponding to the generation of the beam light. The control unit 324 detects cerebral blood flow as a brain function based on the amount of light beam received by the effective light receiving unit 522 with the maximum light receiving efficiency. In this way, the control unit 524 switches the effective light receiving unit 522 that receives the beam light to be detected as the brain function detection target from among the multiple light receiving units 522a, 522b, and 522c.

(Action and Effect)
The effects of the fifth embodiment, which are different from those of the first and third embodiments, will be described below.

In the detection unit 20 of the fifth embodiment, the control unit 524 switches the effective light receiving unit 522 of the beam light to be detected for brain function from among the multiple light receiving units 522a, 522b, and 522c. At this time, the switching is based on the hair ratio Ph, which is the total area of the hair 2c on the head 2a within the spot diameter φ of the beam light emitted from the front, relative to the total area of the spot diameter φ in the irradiation area 3 of the beam light emitted from the front. This makes it possible to select the effective light receiving unit 522 that is likely to receive the beam light diffusely reflected on the head 2a of the subject 2 located in the irradiation area 3, depending on the hair condition of the head 2a. This makes it possible to eliminate a situation in which poor detection of brain function occurs due to other light receiving units that receive an insufficient amount of beam light.

The control unit 524 of the fifth embodiment may switch the effective light receiving unit 522 based on the hair proportion Ph calculated from the captured image of the irradiation area 3. This allows the effective light receiving unit 522 to be accurately selected from the actual captured image so that the amount of light received is increased according to the hair condition of the head 2a. Therefore, it is possible to ensure high reliability in resolving situations in which the amount of light beam received by light receiving units other than the effective light receiving unit 522 is insufficient, leading to poor detection of brain function.

The control unit 524 of the fifth embodiment may switch the effective light receiving unit 522 based on the hair ratio Ph calculated from the amount of beam light received by the light receiving units 522a, 522b, and 522c. This allows the effective light receiving unit 522 to be accurately selected from the actual light receiving results so that the amount of light received is increased according to the hair condition of the head 2a. This makes it possible to ensure high reliability in resolving situations where the amount of beam light received by light receiving units other than the effective light receiving unit 522 is insufficient, leading to poor detection of brain function.

Sixth Embodiment
The sixth embodiment is a modified example of the fifth embodiment. As shown in FIG. 22, in the sixth embodiment, instead of the emission part 314 of the fifth embodiment, which fixes the optical axis direction Dl and the spot diameter φ, an emission part 614 is adopted, which variably adjusts the optical axis direction Dl and fixes the spot diameter φ. Here, the emission part 614 of the sixth embodiment swings the optical axis direction Dl (i.e., the emission direction) of the beam light at least one of diagonally upward and diagonally downward with respect to the front-rear direction of the horizontal direction in the vehicle 4 on the horizontal plane HP. Alternatively, the emission part 614 swings the optical axis direction Dl (i.e., the emission direction) of the beam light at least one of diagonally left and diagonally right with respect to the front-rear direction of the horizontal direction in the vehicle 4 on the horizontal plane HP. Of course, both of these swinging methods may be adopted.

Furthermore, in the sixth embodiment, instead of the control unit 524 that controls the switching of the light receiving units 522a, 522b, and 522c based on the hair ratio Ph, a control unit 624 is adopted that controls the switching of the light receiving units 522a, 522b, and 522c in accordance with the optical axis direction Dl.

Specifically, the control unit 624 of the sixth embodiment selects the effective light receiving unit 522 with the maximum light reception from among the light receiving units 522a, 522b, and 522c in accordance with the change in the optical axis direction Dl of the light beam scanning inside the head 2a in the irradiation area 3. In particular, the control unit 624 controls the generation of the light beam by the light source unit 12 and the variable adjustment of the optical axis direction Dl by the emission unit 614, as well as the reception of the light beam by the effective light receiving unit 522 in response to these. The control unit 624 detects cerebral blood flow as a brain function based on the amount of light beam received by the effective light receiving unit 522 with the maximum light receiving efficiency. In this way, the control unit 624 switches the effective light receiving unit 522 that receives the light beam to be detected as a brain function from among the multiple light receiving units 522a, 522b, and 522c from a perspective different from that of the fifth embodiment.

(Action and Effect)
The effects of the sixth embodiment, which are different from those of the first, third and fifth embodiments described above, will be described below.

In the detection unit 20 of the sixth embodiment, the control unit 624 switches the effective light receiving unit 522 from among the multiple light receiving units 522a, 522b, and 522c in accordance with the optical axis direction Dl of the light beam emitted from the front by the emission unit 614 in the irradiation unit 10 and variably adjusted. This makes it possible to select the effective light receiving unit 522 that is more likely to receive the diffusely reflected light beam depending on the compatibility between the hair condition on the head 2a of the subject 2 located in the irradiation area 3 and the optical axis direction Dl. This makes it possible to eliminate a situation in which poor detection of brain function occurs due to other light receiving units receiving an insufficient amount of light beam.

(Other embodiments)

Although several embodiments have been described above, the present disclosure should not be interpreted as being limited to those embodiments, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

In the modified examples of the first to fourth embodiments, as shown in FIG. 23 (which is a modified example of the first embodiment), the specific angle range Rθ may be defined with the intersection Ic of the horizontal axis Lh and a location on the vertical plane Sv other than the optical axis Al as the center. In the modified examples of the first to fourth embodiments, as shown in FIG. 24 (which is a modified example of the first embodiment), the emission sections 14, 314, and 414 of the irradiation unit 10 may be offset from the orthogonal plane So on which the light receiving sections 22, 222a, 222b, and 222c are arranged due to the definition of the specific angle range Rθ.

In the modified examples of the fifth and sixth embodiments, the light receiving units 522a, 522b, and 522c may be arranged in any angle range centered on the intersection Ic between the horizontal axis Lh and a location on the vertical plane Sv other than the optical axis Al. In the modified examples of the fifth and sixth embodiments, the emission units 14 and 614 of the irradiation unit 10 may be located outside the orthogonal plane So on which the light receiving units 522a, 522b, and 522c are arranged.

In the third and fourth embodiments, a beam of light with an adjusted spot diameter φ may be received by a plurality of light receiving units arranged in a superimposed manner in a specific angle range Rθ in accordance with the second embodiment. In the third and fourth embodiments, a beam of light with a variably adjusted spot diameter φ may be received by a single or a plurality of light receiving units arranged without the requirement of the specific angle range Rθ in accordance with the fifth embodiment. In the fifth and sixth embodiments, switching may be performed among a plurality of light receiving units arranged in a superimposed manner in a specific angle range Rθ in accordance with the second embodiment. In the modified examples of the fifth and sixth embodiments, the spot diameter φ may also be variably adjusted in accordance with the third or fourth embodiment. In the modified example of the sixth embodiment, switching may be performed in accordance with the optical axis direction Dl so as to be based on the hair ratio Ph in accordance with the fifth embodiment.

2 Person to be detected, 2a Head, 3 Irradiation area, 10 Irradiation unit, 12 Light source unit, 14, 314, 414, 614 Emitter unit, 20 Detection unit, 22, 222a, 222b, 222c, 522a, 522b, 522c Light receiving unit, 522 Effective light receiving unit, 24, 224, 324, 424, 524, 624 Control unit, Al Optical axis, Dl Optical axis direction, Ic Intersection, Lh Horizontal axis, Ph Hair ratio, Rθ Specific angle range, So Orthogonal plane, Sv Vertical plane, φ Spot diameter

Claims (5)

an illumination unit (10) having a light source section (12) that generates a beam of light that can be diffusely reflected by a head (2a) of a person to be detected (2) that is located in an illumination area (3), and that emits the beam of light generated by the light source section from the front toward the illumination area;
a detection unit (20) having a plurality of light receiving sections (222a, 222b, 222c) for receiving the light beam diffusely reflected from the irradiation area, and detecting a brain function in the head based on the light beam received by the light receiving sections;
If a vertical plane (Sv) including the optical axis (Al) of the beam light emitted from the irradiation unit and extending above and below the irradiation area and a horizontal axis (Lh) perpendicular to the vertical plane are hypothetically defined,
The plurality of light receiving units are arranged in a superimposed manner within a specific angle range (Rθ) of 45 degrees above and below the horizontal axis, with the intersection (Ic) of the optical axis and the horizontal axis included in the vertical plane as the center,
the detection unit further includes a control unit which calculates a hair ratio (Ph) which is a ratio of a total area of hair (2c) on the head within the spot diameter to an entire area of the spot diameter (φ) in the irradiation region of the light beam, and switches an effective light receiving unit (522) which receives the light beam to be detected for the brain function from among a plurality of light receiving units so that light receiving efficiency at the calculated hair ratio is maximized;
The irradiation unit further includes an emission section that variably adjusts the spot diameter of the emitted beam light in the irradiation area in accordance with the hair ratio,
The emission unit maintains and adjusts the spot diameter when the hair ratio is equal to or less than a threshold value, and increases and adjusts the spot diameter when the hair ratio exceeds the threshold value . If an orthogonal plane (So) perpendicular to the optical axis is virtually defined,
The brain function detection device according to claim 1 , wherein the light receiving sections are arranged so as to overlap in the specific angle range on the orthogonal plane passing through the irradiation unit. 3. The brain function detecting device according to claim 1 , wherein the emission section variably adjusts the spot diameter in accordance with a change in the amount of the light beam received by the light receiving section, which change corresponds to a dimensional change in the spot diameter. The brain function detection device according to any one of claims 1 to 3 , wherein the hair ratio is calculated from a photographed image of the irradiation area. 4. The brain function detection device according to claim 1, wherein the hair ratio is calculated from the amount of the beam light received by the light receiving section.

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