Organism fluid information acquisition device

Abstract

To provide an organism fluid information acquisition device which is compact and has high detection accuracy.SOLUTION: There is provided an organism fluid information acquisition device comprising a light source, a prism, a first light reception element, a second light reception element, a differential circuit, and a signal processor. The prism has a first boundary surface for branching a laser beam emitted from the light source into a first beam and a second beam, a second boundary surface for fully reflecting the second beam, a third boundary surface for fully reflecting the second beam reflected on the second boundary surface, and a fourth boundary surface to which the second beam reflected on the third boundary surface emits. When a width direction of the organism fluid information acquisition device is an X direction, and a thickness direction of the device and being orthogonal to the X direction is a Y direction, an interval between the second boundary surface and the third boundary surface in the Y direction is shorter than an interval between the first boundary surface and the fourth boundary surface in the X direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a biofluid information acquisition device. [Background technology]

[0002] BACKGROUND ART Conventionally, there is known a biological information acquiring device that acquires biological fluid information such as blood flow rate, blood volume, blood flow velocity, and pulse rate in biological tissue by utilizing scattered light from biological tissue (see, for example, Patent Document 1).

[0003] The bioinformation acquisition device described in Patent Document 1 includes a light source that emits laser light, a light branching element that branches the laser light into a first light beam and a second light beam, a first light receiving element that receives the first light beam, a second light receiving element that receives scattered light generated when the second light beam enters an examination site of the living body and is scattered, a differential circuit to which the first light receiving element and the second light receiving element are connected, a signal processing unit that obtains biofluid information by processing the light detection signal output through the differential circuit, and a first light shielding unit that reduces the scattered light from entering the first light receiving element.

[0004] In this biometric information acquisition device, optical branching for differential amplification, prevention of return light for noise reduction, oblique irradiation, etc. are each performed by independent elements. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2022-144578 Summary of the Invention [Problem to be solved by the invention]

[0006] In the biometric information acquisition device described in Patent Document 1, each function is achieved by a plurality of independent elements, which makes the device large and makes it difficult to make it a wearable device. [Means for solving the problem]

[0007] The biofluid information acquisition device of the present invention includes: a light source that emits laser light; a prism that splits the laser light emitted from the light source into a first light beam and a second light beam; a first light receiving element that receives the first light flux; a second light receiving element that receives scattered light obtained from the living body when the second light beam is incident on the examination site of the living body; a differential circuit that generates a light detection signal based on outputs from the first light receiving element and the second light receiving element; a signal processing unit that processes the light detection signal to generate biofluid information, the prism is plate-shaped or column-shaped; the prism has a first boundary surface that splits the laser light emitted from the light source into the first light beam and the second light beam; a second boundary surface that totally reflects the second light beam; a third boundary surface that totally reflects the second light flux reflected by the second boundary surface; a fourth boundary surface from which the second light flux reflected by the third boundary surface exits, When the width direction of the biofluid information acquisition device is defined as the X direction and the thickness direction of the biofluid information acquisition device, which is a direction perpendicular to the X direction, is defined as the Y direction, the distance between the second boundary surface and the third boundary surface in the Y direction is shorter than the distance between the first boundary surface and the fourth boundary surface in the X direction. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing the main parts of an embodiment of a biofluid information acquisition device of the present invention. [Figure 2] FIG. 2 is a block diagram of the biofluid information acquisition device shown in FIG. [Figure 3] 2 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction. [Figure 4]2 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction. [Figure 5] FIG. 2 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1 as viewed from the Z direction, where the angle θa is 30°. [Figure 6] FIG. 2 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1 as viewed from the Z direction, when the angle θa is −10°. [Figure 7] 2 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction. [Figure 8] 2 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A biofluid information acquisition device according to the present invention will be described in detail below based on the embodiments shown in the accompanying drawings.

[0010] <Embodiment> FIG. 1 is a diagram showing the main components of an embodiment of a biofluid information acquisition device of the present invention. FIG. 2 is a block diagram of the biofluid information acquisition device shown in FIG. 1. FIG. 3 is a side view of a prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction. FIG. 4 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction. FIG. 5 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction, where the angle θa is 30°. FIG. 6 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction, where the angle θa is -10°. FIG. 7 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction. FIG. 8 is a side view of the prism of the biofluid information acquisition device shown in FIG. 1, viewed from the Z direction.

[0011] Furthermore, in this specification, for convenience of explanation, the upper side in FIG. 1 will be referred to as "top" or "upper" and the lower side will be referred to as "bottom" or "lower".

[0012] As shown in Figure 1, the X-axis, Y-axis, and Z-axis are shown as three mutually orthogonal axes. The tip end of the arrow indicating each axis is designated "+: positive," and the base end is designated "-: negative." The direction parallel to the X-axis is also referred to as the "X direction: X-axis direction," the direction parallel to the Y-axis is also referred to as the "Y direction: Y-axis direction," and the direction parallel to the Z-axis is also referred to as the "Z direction: Z-axis direction."

[0013] The width direction of the biofluid information acquisition device 1 is defined as the X direction, the thickness direction of the biofluid information acquisition device 1 is defined as the Y direction, and the length direction of the biofluid information acquisition device 1 is defined as the Z direction.

[0014] In each drawing, the center lines of the light beams, that is, the light rays, are shown for the laser light L, the first light beam L1, the second light beam L2, and the scattered light L3.

[0015] 1 shows only a portion of the housing 31 of the biofluid information acquisition device 1, rather than the entirety of it. Also, in FIG. 2, only some of the signal and control lines are shown.

[0016] The biofluid information acquisition device 1 shown in FIG. 1 is a device for acquiring biofluid information of a subject, which is a living body 100.

[0017] Furthermore, biological fluid information is information relating to the fluid in the living body 100, and examples thereof include blood flow rate, blood volume, blood flow velocity, pulse rate, blood pressure, pulse wave velocity, arteriosclerosis level, and volume pulse wave in the living body 100.

[0018] Furthermore, the form of the biofluid information acquisition device 1 is not particularly limited, and various forms can be mentioned, such as a form in which it is worn by a subject and used, a stationary form, etc. In this embodiment, however, we will explain the case where it is applied to a form in which it is worn by a subject and used.

[0019] 1 and 2, the biofluid information acquisition device 1 has a housing 31 that houses and supports each component of the biofluid information acquisition device 1. The housing 31 is box-shaped, and its outer shape is a rectangular parallelepiped. However, the shape of the housing 31 is not limited to this.

[0020] The biofluid information acquisition device 1 also includes a circuit board 2 having various electronic components, circuits, etc. The circuit board 2 is disposed in, or housed in, a housing 31.

[0021] The biofluid information acquisition device 1 also includes a light source 3 that emits laser light L, a first light-receiving element 5, a second light-receiving element 6, a differential circuit 7, a signal processing unit 8 that generates biofluid information, a control unit 9 that controls the operation of the biofluid information acquisition device 1, a memory unit 11 that stores various information and programs, a display unit 12 that displays various information, and an operation unit 13 that is an input unit for various instructions and various inputs. The light source 3, the first light-receiving element 5, the second light-receiving element 6, the differential circuit 7, the signal processing unit 8, the control unit 9, the memory unit 11, the display unit 12, and the operation unit 13 are each electrically connected to a circuit board 2, and certain components thereof are arranged on the circuit board 2.

[0022] The biofluid information acquisition device 1 also has a prism 4, a collimating lens 21, a condensing lens 22, a cover glass 23 that serves as a cover plate, and a light reflecting member 24. The prism 4, collimating lens 21, condensing lens 22, and light reflecting member 24 are disposed, i.e., housed, in a housing 31. The cover glass 23 is disposed at the bottom of the housing 31, i.e., at the end of the housing 31 on the negative side in the Y direction, and is supported by the housing 31 and exposed to the outside.

[0023] The circuit board 2 is disposed in the upper part of the housing 31, i.e., at the end of the housing 31 on the + side in the Y direction, and the light source 3, the first light receiving element 5, and the second light receiving element 6 are disposed in the upper part of the housing 31. In this case, the first light receiving element 5 is disposed on the left side of the light source 3 in FIG. 1, i.e., on the - side in the X direction, and the second light receiving element 6 is disposed on the right side of the light source 3 in FIG. 1, i.e., on the + side in the X direction.

[0024] The prism 4 is disposed on the optical path between the light source 3 and the cover glass 23. The prism 4 has a function of splitting the laser light L emitted from the light source 3 into a first light beam L1 and a second light beam L2. The prism 4 and the configuration related to the prism 4 will be described in detail later.

[0025] The cover glass 23 is disposed on the negative side of the second light receiving element 6 in the Y direction, at the bottom of the housing 31, i.e., at the end of the housing 31 on the negative side in the Y direction. This cover glass 23 is the part that comes into contact with the living organism 100 when the biofluid information acquisition device 1 is attached to the living organism 100, and has the function of protecting the inside of the biofluid information acquisition device 1. The cover plate is not limited to the cover glass 23, and its constituent material is not limited to glass material, but may include, for example, a resin material. The cover glass 23 may be configured to be spaced apart from the living organism 100 when the biofluid information acquisition device 1 is attached to the living organism 100.

[0026] The cover glass 23 is plate-shaped and optically transparent. The second light beam L2 emitted from the fourth boundary surface 44 of the prism 4 passes through the cover glass 23, and the scattered light L3 obtained from the living body 100 also passes through the cover glass 23.

[0027] In addition, the collimating lens 21 is disposed on the optical path between the light source 3 and the first boundary surface 41 of the prism 4 .

[0028] The condenser lens 22 is disposed on the optical path between the second light receiving element 6 and the cover glass 23 .

[0029] Furthermore, the light reflecting member 24 is disposed on the optical path between the first light receiving element 5 and the first boundary surface 41 of the prism 4. This light reflecting member 24 has a function of reflecting the first light flux L1 reflected by the first boundary surface 41 toward the first light receiving element 5. Examples of the light reflecting member 24 include a prism and a reflecting plate.

[0030] The light source 3 has a function of emitting laser light L. The light source 3 is not particularly limited, and examples thereof include a semiconductor laser.

[0031] The first light receiving element 5 has a function of receiving the first light flux L1. The first light receiving element 5 is not particularly limited, and examples thereof include a photodiode and a phototransistor.

[0032] The second light receiving element 6 has a function of receiving scattered light L3 obtained from the living body 100 when the second light beam L2 is incident on the test site of the living body 100. The second light receiving element 6 is not particularly limited, and examples thereof include a photodiode and a phototransistor.

[0033] The differential circuit 7 also has a function of generating a light detection signal based on the outputs of the first light receiving element 5 and the second light receiving element 6. That is, the differential circuit 7 converts the detection currents output from the first light receiving element 5 and the second light receiving element 6 into voltage signals, generates a signal corresponding to the difference between the voltage signals, and outputs it as a light detection signal.

[0034] The signal processing unit 8 is configured to include an arithmetic circuit such as a CPU (Central Processing Unit) and can be realized as one or more processors, and reads and executes various programs stored in the memory unit 11. The signal processing unit 8 also generates biofluid information by processing the light detection signal. Note that a known method can be used to determine the biofluid information based on the light detection signal, and therefore a description thereof will be omitted.

[0035] The control unit 9 is configured to include an arithmetic circuit such as a CPU (Central Processing Unit) and can be realized as one or more processors, and reads and executes various programs stored in the storage unit 11. This allows the control of the operation of the biofluid information acquisition device 1 and various processes such as various calculations and various judgments to be performed.

[0036] The processors that realize the control unit 9 and the signal processing unit 8 may be provided separately, or all or part of them may be shared.

[0037] The storage unit 11 also stores various programs that can be executed by the control unit 9. The storage unit 11 is also capable of storing various data input from the outside. The storage unit 11 is configured to include, for example, a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory). The storage unit 11 is not limited to being non-detachable, and may be configured to include a detachable external storage device.

[0038] Display unit 12 is an example of a notification unit that notifies information, and has a function of displaying various types of information, such as biofluid information, etc. Display unit 12 is not particularly limited, and examples thereof include a liquid crystal display device and an organic EL display device.

[0039] The operation unit 13 is not particularly limited and may be, for example, an operation button, an operation switch, an operation dial, etc. By operating the operation unit 13, the subject can issue various instructions and input various information to the biofluid information acquisition device 1.

[0040] Furthermore, a display input unit having the functions of the display unit 12 and the operation unit 13 may be used instead of the display unit 12 and the operation unit 13, or together with the display unit 12 and the operation unit 13. As the display input unit, for example, a touch panel or the like may be used.

[0041] Next, the prism 4 and the configuration related to the prism 4 will be described. The prism 4 has a function of splitting the laser light L emitted from the light source 3 into a first light beam L1 and a second light beam L2.

[0042] The prism 4 is made of various resin materials, various glass materials, etc. The prism 4 may be formed as a single unit, or may be made up of multiple members.

[0043] The prism 4 has a plate or columnar shape. In this embodiment, the prism 4 has the shape shown in Figures 1 and 3 when viewed from the Z direction, and the two surfaces of the prism 4 in the Z direction are flat. However, the shapes of the two surfaces of the prism 4 in the Z direction may be other shapes.

[0044] The following describes the various conditions of the shape, orientation, and arrangement of the prism 4 when viewed from the Z direction.

[0045] As shown in FIGS. 1 and 3 , when viewed from the Z direction, the prism 4 has a first boundary surface 41, a second boundary surface 42, a third boundary surface 43, a fourth boundary surface 44, a fifth boundary surface 45, and a sixth boundary surface 46, which are boundaries with air. Each of the boundary surfaces 41 to 46 is a portion of the surface of the prism 4. Each of the boundary surfaces 41 to 46 is flat and linear when viewed from the Z direction. In this specification, the first boundary surface 41 will also be referred to simply as the "boundary surface 41," the second boundary surface 42 will also be referred to simply as the "boundary surface 42," the third boundary surface 43 will also be referred to simply as the "boundary surface 43," the fourth boundary surface 44 will also be referred to simply as the "boundary surface 44," the fifth boundary surface 45 will also be referred to simply as the "boundary surface 45," and the sixth boundary surface 46 will also be referred to simply as the "boundary surface 46."

[0046] The boundary surface 41 of the prism 4 is a site where the laser light L emitted from the light source 3 is split into a first light beam L1 and a second light beam L2. That is, the laser light L is split at the boundary surface 41 into the first light beam L1 that is reflected at the boundary surface 41 and the second light beam L2 that is transmitted through the boundary surface 41.

[0047] In addition, a polarization separation film 47 is disposed on the boundary surface 41. As a result, the first light beam L1, which is reflected light, is S-polarized light, and the second light beam L2, which is transmitted light, is P-polarized light. Note that the polarization separation film 47 may be omitted.

[0048] Furthermore, boundary surface 42 is a portion that totally reflects second light beam L2 that has passed through boundary surface 41. Furthermore, boundary surface 43 is a portion that totally reflects second light beam L2 that has been reflected by boundary surface 42. Furthermore, boundary surface 44 is a portion from which second light beam L2 that has been reflected by boundary surface 43 is emitted. Furthermore, boundary surfaces 45 and 46 are unused portions. Note that in the drawings, center lines of light beams, i.e., light rays, are shown for laser light L, first light beam L1, and second light beam L2.

[0049] The boundaries 41 to 46 are arranged in the following order clockwise from the boundary 41: boundary 41, boundary 46, boundary 43, boundary 44, boundary 45, and boundary 42.

[0050] Furthermore, the boundary surface 41 and the boundary surface 44 are disposed opposite to each other. Furthermore, although the boundary surface 41 and the boundary surface 44 are parallel to each other in this embodiment, the present invention is not limited to this and they may be non-parallel to each other.

[0051] The boundary surface 42 and the boundary surface 43 are disposed opposite to each other. In the present embodiment, the boundary surface 42 and the boundary surface 43 are not parallel to each other, but the boundary surface 42 and the boundary surface 43 may be parallel to each other.

[0052] Furthermore, boundary surface 45 is disposed between boundary surface 42 and boundary surface 44. One end of boundary surface 45 is connected to the end of boundary surface 42, and the other end of boundary surface 45 is connected to the end of boundary surface 44. The portion of prism 4 corresponding to boundary surface 45 is unused. By providing such boundary surface 45 and shaping prism 4 so that a portion of prism 4 is cut out, the length of prism 4 in the Y direction is shorter than when boundary surface 45 is not provided. This allows the thickness of biofluid information acquisition device 1 to be thinner, enabling the biofluid information acquisition device 1 to be made smaller and thinner.

[0053] Furthermore, boundary surface 46 is disposed between boundary surface 41 and boundary surface 43. One end of boundary surface 46 is connected to the end of boundary surface 43. The angle θ formed by boundary surface 43 and boundary surface 46 on the prism 4 side is greater than 180°. As a result, notches are formed in prism 4 that are cut out at boundary surface 43 and boundary surface 46, thereby shortening the optical path length in prism 4. This allows the thickness and width of biofluid information acquisition device 1 to be reduced, thereby enabling the biofluid information acquisition device 1 to be made smaller.

[0054] The width direction of the biofluid information acquisition device 1, i.e., the width direction of the housing 31, is defined as the X direction, and the thickness direction of the biofluid information acquisition device 1, i.e., the thickness direction of the housing 31, which is perpendicular to the X direction, is defined as the Y direction. The distance between the boundary surface 42 and the boundary surface 43 in the Y direction is defined as t 2_3 The distance between the boundary surface 41 and the boundary surface 44 in the X direction is defined as t 1_4 Let this t 2_3 is the distance between the boundary surface 42 and the boundary surface 43, and t 1_4 is the distance between the boundary surface 41 and the boundary surface 44. When defined in this way, the distance between the boundary surface 42 and the boundary surface 43 in the Y direction, that is, the distance t 2_3 is the distance between the boundary surface 41 and the boundary surface 44 in the X direction, that is, the distance t 1_4This allows the length of the prism 4 in the Y direction to be shortened, thereby enabling the biofluid information acquisition device 1 to be made smaller, and in particular thinner, thereby reducing the burden on the subject.

[0055] Furthermore, in such a prism 4, the second light beam L2 reflected at the boundary surface 43 can be prevented from being reflected at the boundary surface 44 and returning to the boundary surface 41 side within the prism 4, thereby enabling accurate acquisition of biofluid information.

[0056] Below, preferable conditions for each of the conditions of the prism 4 will be explained, but the present invention is not limited to these.

[0057] The beam diameter of the laser light L emitted from the light source 3 is D0. The beam diameter of the laser light L at the boundary surface 41 is D1. The beam diameter of the second light beam L2 at the boundary surface 42 is D2. The beam diameter of the second light beam L2 at the boundary surface 43 is D3. The incident angle of the laser light L on the boundary surface 41 is θ1, The incident angle of the second light beam L2 on the boundary surface 42 is θ2. The distance between the boundary surface 41 and the boundary surface 44 is t 1_4 When the distance t 1_4 satisfies the following formula (1).

[0058]

number

[0059] This prevents the second light beam L2 reflected at the boundary surface 43 from being reflected at the boundary surface 44 and returning to the boundary surface 41 side within the prism 4, thereby enabling accurate acquisition of biofluid information. The beam diameter D0 is the beam diameter after the collimator lens 21.

[0060] In addition, the distance between the boundary surface 42 and the boundary surface 43 is t 2_3When the distance t 2_3 satisfies the following formula (2).

[0061]

number

[0062] This allows the length of the prism 4 in the Y direction to be shortened, thereby enabling the biofluid information acquisition device 1 to be made smaller, and in particular thinner.

[0063] The beam diameter D1 of the laser light L at the boundary surface 41 is expressed by the following formula (5). D1=D0 / sin(90-θ1) (5)

[0064] Also, the refractive index of the prism 4 is n t , The refractive index of air is n i , When the incident angle of the second light beam L2 on the boundary surface 43 is θ3, The relationship θ2≦θ3 is satisfied, which allows the length of the prism 4 in the Y direction to be shortened.

[0065] Moreover, the incident angle θ2 satisfies the following formula (3).

[0066]

number

[0067] Moreover, the incident angle θ3 satisfies the following formula (4).

[0068]

number

[0069] This allows the angle of incidence of the second light beam L2 on the living body 100 to be approximately 45°, suppressing the capture of reflected light by the cover glass 23 and enabling accurate acquisition of biofluid information. Also, the length of the prism 4 in the Y direction can be shortened, allowing the biofluid information acquisition device 1 to be made smaller, particularly thinner.

[0070] Here, in the above formula (3), if θ2 is equal to or less than the value of the right-hand side, total reflection does not occur at the boundary surface 42, depending on other conditions.

[0071] Furthermore, in the above formula (3), if θ2 is equal to or greater than the value on the left side, the prism 4 becomes large depending on other conditions.

[0072] Furthermore, in the above formula (4), if θ3 is equal to or less than the value of the right-hand side, total reflection does not occur at the boundary surface 43, depending on other conditions.

[0073] Furthermore, in the above formula (4), if θ3 is equal to or greater than the value on the left side, the prism 4 becomes large depending on other conditions.

[0074] 4, when viewed from the Z direction, a line segment Q is assumed to connect the center P1 of the second light beam L2 at the boundary surface 42 with the center P2 of the second light beam L2 at the boundary surface 43. In this case, the center P1 is the center of the incident range R2 of the second light beam L2 at the boundary surface 42, and the center P2 is the center of the incident range R3 of the second light beam L2 at the boundary surface 43.

[0075] The Y-direction component QY of the line segment Q is shorter than the X-direction component QX of the line segment Q. This allows the length of the prism 4 in the Y direction to be shortened, thereby enabling the biofluid information acquisition device 1 to be made smaller, and in particular thinner.

[0076] Furthermore, the orientation of the prism 4 in the biofluid information acquisition device 1 is not particularly limited and may be set appropriately depending on the required conditions. In this embodiment, as shown in Figures 5 and 6, the angle θa of the second boundary surface 42 relative to the cover glass 23 when viewed from the Z direction is between -10° and 30°. This allows the biofluid information acquisition device 1 to be made thinner. Furthermore, the angle θa is a value relative to the surface of the cover glass 23.

[0077] 5 shows the case where the angle θa is +30°, and Fig. 6 shows the case where the angle θa is -10°, and the orientation of the prism 4 with respect to the cover glass 23 can be set within the above range. Therefore, it is also possible to set the angle θa to, for example, 0, that is, to set the orientation of the prism 4 so that the second boundary surface 42 and the surface of the cover glass 23 are parallel to each other.

[0078] 7, the center P of the second light beam L2 incident on the cover glass 23 is G The position of the center P is located closer to the prism 4 than the optical axis 52 of the condenser lens 22. G In other words, this is the center of the incident range R4 of the second light beam L2 on the cover glass 23. This makes it possible to improve the utilization efficiency of the scattered light L3 obtained from the examination site of the living body 100.

[0079] Also, the center P G and the distance t between the position A of the optical axis 52 on the incident surface of the cover glass 23. G is greater than 0 and equal to or less than 2 mm. This makes it possible to improve the efficiency of use of scattered light L3 obtained from the test site of the living body 100. G is more preferably 0.25 mm or more and 2 mm or less. This makes it possible to further increase the utilization efficiency of the scattered light L3 obtained from the examination site of the living body 100.

[0080] 8, the point located closest to the collimator lens 21 in the incident range R1 of the laser light L emitted from the light source 3 on the boundary surface 41 as viewed from the Z direction is designated as P. P The vertex of the collimator lens 21 on the boundary surface 41 side is P L Let's say.

[0081] point P P and vertex P L The distance t in the direction of the optical axis 51 of the collimator lens 21 L_P is greater than 0.

[0082] This makes it possible to prevent the first light beam L1 reflected by the boundary surface 41 from interfering with the collimator lens 21.

[0083] Next, the procedure for acquiring biofluid information using the biofluid information acquisition device 1 and the operation of the biofluid information acquisition device 1 will be described with reference to FIGS.

[0084] First, the subject attaches the biofluid information acquisition device 1 to the living body 100 so that the cover glass 23 of the biofluid information acquisition device 1 is placed at the examination site of the living body 100.

[0085] When laser light L is emitted from the light source 3, the laser light L is converted into parallel light by the collimator lens 21 and enters the boundary surface 41 of the prism 4, where it is split into a first light beam L1 and a second light beam L2. That is, the laser light L is split into the first light beam L1 reflected by the boundary surface 41 and the second light beam L2 transmitted through the boundary surface 41.

[0086] The first light beam L1 is reflected by the light reflecting member 24, enters the first light receiving element 5, and is received by the first light receiving element 5. The first light receiving element 5 outputs a detection current to the differential circuit 7 in accordance with the amount of received light.

[0087] The second light beam L2 is reflected by the boundary surface 42, reflected by the boundary surface 43, emitted from the boundary surface 44, transmitted through the cover glass 23, and incident on, i.e., irradiated with, the examination site of the living body 100. As a result, scattered light L3 is emitted from the examination site of the living body 100.

[0088] Furthermore, scattered light L3 obtained from the examination site of the living body 100 is collected by the collecting lens 22, incident on the second light receiving element 6, and received by the second light receiving element 6. Furthermore, a detection current corresponding to the amount of received light is output from the second light receiving element 6 to the differential circuit 7.

[0089] In addition, the differential circuit 7 converts the detection currents output from the first light receiving element 5 and the second light receiving element 6 into voltage signals, generates a signal corresponding to the difference between the voltage signals, and outputs it to the signal processing unit 8 as a light detection signal.

[0090] The signal processor 8 processes the light detection signal to generate predetermined biofluid information, such as blood flow rate, blood volume, blood flow velocity, pulse rate, blood pressure, pulse wave velocity, arteriosclerosis level, and volume pulse wave. The acquired biofluid information is stored in the storage unit 11 and is read out as needed.

[0091] The acquired biofluid information is also displayed on the display unit 12. This allows the subject to understand the biofluid information.

[0092] As described above, according to the biofluid information acquisition device 1, by using the above-described prism 4, it is possible to shorten the length of the prism 4 in the Y direction, thereby achieving a reduction in the size, and in particular, the thickness, of the biofluid information acquisition device 1. This reduces the burden on the subject.

[0093] In addition, the second light beam L2 reflected at the boundary surface 43 of the prism 4 can be prevented from being reflected at the boundary surface 44 and returning to the boundary surface 41 side within the prism 4, thereby enabling accurate acquisition of biofluid information.

[0094] <Other configurations> The biofluid information acquisition device 1 may have the configuration described below, and this configuration may be applied to the above-described embodiments.

[0095] <<Configuration 1>> A predetermined amount, for example, 3% of the laser light L emitted from the light source 3 may be reflected by the first boundary surface 41 of the prism 4 and incident on the reference light-receiving element as reference light. This improves the signal-to-noise ratio of the light detection signal, thereby enabling accurate acquisition of biofluid information.

[0096] Furthermore, when a plate-shaped optical branching element is used instead of the prism 4, it is necessary to consider not only the light reflected on the surface of the optical branching element but also the light reflected on the back surface of the branching element, so it is necessary to provide a light intensity adjustment mechanism.However, in this embodiment, since the prism 4 is used, there is no need to provide a light intensity adjustment mechanism, which simplifies the configuration.

[0097] <<Configuration 2>> A light-shielding portion having an opening that passes a portion of the laser light L emitted from the light source 3 and blocks the remainder may be provided on the first boundary surface 41 of the prism 4. This light-shielding portion can be formed, for example, by pinhole processing or the like.

[0098] <<Configuration 3>> At least a part of the differential circuit 7 may be configured by a circuit having a differential amplifier or the like, and the light detection signal may be generated by this circuit.

[0099] <<Configuration 4>> At least a part of the differential circuit 7 may be configured as an arithmetic processing unit that performs arithmetic processing, such as subtraction, to calculate the photodetection signal.

[0100] As described above, the biofluid information acquisition device 1 comprises a light source 3 that emits laser light L, a prism 4 that splits the laser light L emitted from the light source 3 into a first light beam L1 and a second light beam L2, a first light receiving element 5 that receives the first light beam L1, a second light receiving element 6 that receives scattered light L3 obtained from the living body 100 when the second light beam L2 enters the test area of ​​the living body 100, a differential circuit 7 that generates a light detection signal based on the output of the first light receiving element 5 and the second light receiving element 6, and a signal processing unit 8 that generates biofluid information by processing the light detection signal.

[0101] The prism 4 has a plate-like or columnar shape and includes a first boundary surface 41 that splits the laser light L emitted from the light source 3 into a first light beam L1 and a second light beam L2, a second boundary surface 42 that totally reflects the second light beam L2, a third boundary surface 43 that totally reflects the second light beam L2 reflected by the second boundary surface 42, and a fourth boundary surface 44 from which the second light beam L2 reflected by the third boundary surface 43 exits.

[0102] Furthermore, when the width direction of the biofluid information acquisition device 1 is defined as the X direction and the thickness direction of the biofluid information acquisition device 1, which is a direction perpendicular to the X direction, is defined as the Y direction, the distance between the second boundary surface 42 and the third boundary surface 43 in the Y direction is shorter than the distance between the first boundary surface 41 and the fourth boundary surface 44 in the X direction.

[0103] According to this biofluid information acquisition device 1, the length of the prism 4 in the Y direction can be shortened, which allows for a reduction in size, and in particular, thickness, of the biofluid information acquisition device 1. This reduces the burden on the subject.

[0104] In addition, the second light beam L2 reflected by the third boundary surface 43 of the prism 4 can be prevented from being reflected by the fourth boundary surface 44 and returning to the first boundary surface 41 inside the prism 4, thereby enabling accurate acquisition of biofluid information.

[0105] In addition, in the biofluid information acquisition device 1, the beam diameter of the laser light L emitted from the light source 3 is defined as D0, The beam diameter of the second light beam L2 at the second boundary surface 42 is D2. The beam diameter of the second light beam L2 at the third boundary surface 43 is D3. The incident angle of the laser light L on the first boundary surface 41 is θ1, The incident angle of the second light beam L2 on the second boundary surface 42 is θ2. The distance between the first boundary surface 41 and the fourth boundary surface 44 is t 1_4 When the distance t 1_4 satisfies the following formula (1).

[0106]

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[0107] This prevents the second light beam L2 reflected by the third boundary surface 43 from being reflected by the fourth boundary surface 44 and returning to the first boundary surface 41 within the prism 4, thereby enabling accurate acquisition of biofluid information.

[0108] In addition, in the biofluid information acquisition device 1, the beam diameter of the laser light L emitted from the light source 3 is defined as D0, The beam diameter of the second light beam L2 at the second boundary surface 42 is D2. The incident angle of the laser light L on the first boundary surface 41 is θ1, The incident angle of the second light beam L2 on the second boundary surface 42 is θ2. The distance between the second boundary surface 42 and the third boundary surface 43 is t 2_3 When the distance t 2_3 satisfies the following formula (2).

[0109]

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[0110] This allows the length of the prism 4 in the Y direction to be shortened, thereby enabling the biofluid information acquisition device 1 to be made smaller, and in particular thinner.

[0111] Furthermore, in the biofluid information acquisition device 1, when the direction perpendicular to the X and Y directions is defined as the Z direction, when viewed from the Z direction, the Y-direction component QY of the line segment Q connecting the center P1 of the second light beam L2 at the second boundary surface 42 and the center P2 of the second light beam L2 at the third boundary surface 43 is shorter than the X-direction component QX of the line segment Q.

[0112] This allows the length of the prism 4 in the Y direction to be shortened, thereby enabling the biofluid information acquisition device 1 to be made smaller, and in particular thinner.

[0113] The biofluid information acquisition device 1 also has a housing 31 that houses the prism 4, and a cover glass 23 that is disposed in the housing 31 and that is a cover plate through which the second light beam L2 emitted from the fourth boundary surface 44 passes. The angle θa of the second boundary surface 42 relative to the cover glass 23 is between −10° and 30°. This allows the biofluid information acquisition device 1 to be made thinner.

[0114] In addition, in the biofluid information acquisition device 1, the refractive index of the prism 4 is set to n t , The refractive index of air is n i , The beam diameter of the laser light L emitted from the light source 3 is D0. The beam diameter of the second light beam L2 at the second boundary surface 42 is D2. The incident angle of the laser light L on the first boundary surface 41 is θ1, The incident angle of the second light beam L2 on the second boundary surface 42 is θ2. When the incident angle of the second light beam L2 on the third boundary surface 43 is θ3, The incident angle θ2 satisfies the following formula (3), and the incident angle θ3 satisfies the following formula (4), and θ2≦θ3.

[0115]

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[0116]

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[0117] This allows the angle of incidence of the second light beam L2 on the living body 100 to be approximately 45°, suppressing the capture of reflected light by the cover glass 23 and enabling accurate acquisition of biofluid information. Also, the length of the prism 4 in the Y direction can be shortened, allowing the biofluid information acquisition device 1 to be made smaller, particularly thinner.

[0118] The biofluid information acquisition device 1 also includes a housing 31 that houses the prism 4, a condenser lens 22 that is disposed in the housing 31 and that condenses the scattered light L3 onto the second light receiving element 6, and a cover glass 23 that is disposed in the housing 31 and that is a cover plate through which the second light beam L2 emitted from the fourth boundary surface 44 passes. When the direction orthogonal to the X direction and the Y direction is defined as the Z direction, the center P of the cover glass 23 of the second light beam L2 that is incident on the cover glass 23 as viewed from the Z direction is G The position of is located closer to the prism 4 than the optical axis 52 of the condenser lens 22, and the center P G and the distance t between the optical axis 52 and the position A on the cover glass 23. G is greater than 0 and less than or equal to 2 mm.

[0119] This makes it possible to improve the utilization efficiency of the scattered light L3 obtained from the region of the living body 100 to be examined.

[0120] The biofluid information acquisition device 1 also has a collimator lens 21 disposed between the light source 3 and the first boundary surface 41, through which the laser light L emitted from the light source 3 passes. When the direction perpendicular to the X and Y directions is defined as the Z direction, the point P located closest to the collimator lens 21 within the incident range R1 of the laser light L emitted from the light source 3 on the first boundary surface 41 as viewed from the Z direction is defined as P and the vertex P of the collimator lens 21 on the first boundary surface 41 side. L The distance t in the direction of the optical axis 51 of the collimator lens 21 L_P is greater than 0.

[0121] This makes it possible to prevent the first light beam L1 reflected by the first boundary surface 41 from interfering with the collimator lens .

[0122] Furthermore, in the biofluid information acquisition device 1, when the direction perpendicular to the X direction and Y direction is defined as the Z direction, when viewed from the Z direction, the prism 4 has a fifth boundary surface 45 between the second boundary surface 42 and the fourth boundary surface 44.

[0123] By providing such an interface 45 and making the shape of the prism 4 such that a portion of the prism 4 is cut out, the length of the prism 4 in the Y direction is shorter than when the interface 45 is not provided, thereby making it possible to reduce the thickness of the biofluid information acquisition device 1 and making the biofluid information acquisition device 1 smaller and thinner.

[0124] While the biofluid information acquisition device of the present invention has been described above based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part can be replaced with any configuration having a similar function. In addition, any other components may be added. [Explanation of symbols]

[0125] DESCRIPTION OF SYMBOLS 1...Biofluid information acquisition device 2...Circuit board 3...Light source 4...Prism 41...First boundary surface 42...Second boundary surface 43...Third boundary surface 44...Fourth boundary surface 45...Fifth boundary surface 46...Sixth boundary surface 47...Polarization separation film 5...First light receiving element 6...Second light receiving element 7...Differential circuit 8...Signal processing unit 9...Control unit 11...Memory unit 12...Display unit 13...Operation unit 21...Collimating lens 22...Condenser lens 23...Cover glass 24...Light reflecting member 31...Housing 51...Optical axis 52...Optical axis 100...Body A...Position D0...Beam diameter D1...Beam diameter D2...Beam diameter D3...Beam diameter L...Laser light L1...First light beam L2...Second light beam L3...Scattered light P1...Center P2...Center P G …Center P L …Vertex P P...point Q...line segment QX...component QY...component R1...incident range R2...incident range R3...incident range R4...incident range t 1_4 ...distance t 2_3 ...distance t G ...distance t L_P ...distance θ...angle θ1...incident angle θ2...incident angle θ3...incident angle θa...angle

Claims

1. a light source that emits laser light; a prism that splits the laser light emitted from the light source into a first light beam and a second light beam; a first light receiving element that receives the first light flux; a second light receiving element that receives scattered light obtained from the living body when the second light beam is incident on the examination site of the living body; a differential circuit that generates a light detection signal based on outputs from the first light receiving element and the second light receiving element; a signal processing unit that processes the light detection signal to generate biofluid information, the prism is plate-shaped or column-shaped; the prism has a first boundary surface that splits the laser light emitted from the light source into the first light beam and the second light beam; a second boundary surface that totally reflects the second light beam; a third boundary surface that totally reflects the second light flux reflected by the second boundary surface; a fourth boundary surface from which the second light flux reflected by the third boundary surface exits, A biofluid information acquisition device characterized in that, when the width direction of the biofluid information acquisition device is defined as the X direction and the thickness direction of the biofluid information acquisition device, which is a direction perpendicular to the X direction, is defined as the Y direction, the distance between the second boundary surface and the third boundary surface in the Y direction is shorter than the distance between the first boundary surface and the fourth boundary surface in the X direction.

2. The beam diameter of the laser light emitted from the light source is D ０ , The beam diameter of the second light beam at the second boundary surface is defined as D ２ , The beam diameter of the second light beam at the third boundary surface is defined as D ３ , The incident angle of the laser light on the first boundary surface is defined as θ １ , The incident angle of the second light beam on the second boundary surface is defined as θ ２ , The distance between the first boundary surface and the fourth boundary surface is t １＿４ When the distance t １＿４ The biofluid information acquisition device according to claim 1 , wherein the following formula (1) is satisfied: [Equation 1]

3. The beam diameter of the laser light emitted from the light source is D ０ , The beam diameter of the second light beam at the second boundary surface is defined as D ２ , The incident angle of the laser light on the first boundary surface is defined as θ １ , The incident angle of the second light beam on the second boundary surface is defined as θ ２ , The distance between the second boundary surface and the third boundary surface is t ２＿３ When the distance t ２＿３ The biofluid information acquisition device according to claim 1 , wherein the following formula (2) is satisfied: [Equation 2]

4. When the direction perpendicular to the X direction and the Y direction is defined as the Z direction, A biofluid information acquisition device as described in claim 1, wherein, when viewed from the Z direction, the Y-direction component of the line segment connecting the center of the second light beam at the second boundary surface and the center of the second light beam at the third boundary surface is shorter than the X-direction component of the line segment.

5. a housing that houses the prism; a cover plate disposed on the housing and through which the second light flux emitted from the fourth boundary surface passes, 2. The biofluid information acquisition device according to claim 1, wherein the angle of the second boundary surface relative to the cover plate is between −10° and 30°.

6. The refractive index of the prism is n ｔ , The refractive index of air is n ｉ , The beam diameter of the laser light emitted from the light source is D ０ , The beam diameter of the second light beam at the second boundary surface is defined as D ２ , The incident angle of the laser light on the first boundary surface is defined as θ １ , The incident angle of the second light beam on the second boundary surface is defined as θ ２ , The incident angle of the second light beam on the third boundary surface is defined as θ ３ When The incident angle θ ２ satisfies the following formula (3), and the incident angle θ ３ satisfies the following formula (4), and θ ２ ≦θ ３ The biofluid information acquisition device according to claim 1 . [Equation 3] [Equation 4]

7. a housing that houses the prism; a condenser lens disposed in the housing and configured to condense the scattered light onto the second light receiving element; a cover plate disposed on the housing and through which the second light flux emitted from the fourth boundary surface passes, When the direction perpendicular to the X direction and the Y direction is defined as the Z direction, When viewed from the Z direction, a center position on the cover plate of the second light flux incident on the cover plate is located closer to the prism than the optical axis of the condenser lens; The biofluid information acquisition device according to claim 1 , wherein the distance between the center and the position of the optical axis on the cover plate is greater than 0 and equal to or less than 2 mm.

8. a collimator lens disposed between the light source and the first boundary surface, through which the laser light emitted from the light source passes; When the direction perpendicular to the X direction and the Y direction is defined as the Z direction, When viewed from the Z direction, A biofluid information acquisition device as described in claim 1, wherein the distance in the optical axis direction of the collimating lens between the point located closest to the collimating lens within the incident range of the laser light emitted from the light source at the first boundary surface and the vertex of the collimating lens on the first boundary surface side is greater than 0.

9. When the direction perpendicular to the X direction and the Y direction is defined as the Z direction, When viewed from the Z direction, The biofluid information acquisition device according to claim 1 , wherein the prism has a fifth boundary surface between the second boundary surface and the fourth boundary surface.

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