Measuring device

Abstract

To provide a technique that can accurately measure the flow rate of blood.SOLUTION: When a light receiving signal to be sampled at a time tn is a first light receiving signal, a light receiving signal to be sampled at a time tn-1 is a second light receiving signal, and a light receiving signal to be sampled at a time tn-2 is the first light receiving signal, a processing apparatus may estimate a fourth frequency spectrum that is a frequency spectrum when a light receiving signal to be sampled at the time tn-1 is assumed to be the first light receiving signal, on the basis of a first frequency spectrum, a second frequency spectrum, and a third frequency spectrum.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a measurement device. [Background technology]

[0002] Patent Document 1 discloses an apparatus for determining blood flow velocity based on Doppler shift frequency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-028891 Summary of the Invention [Problem to be solved by the invention]

[0004] Two laser beams (a first laser beam and a second laser beam) may be used to measure the blood flow velocity. In this method, the blood flow velocity is determined based on the frequency spectrum obtained when both the first laser beam and the second laser beam are irradiated onto the blood, and the frequency spectrum obtained when either the first laser beam or the second laser beam is irradiated onto the blood.

[0005] However, if the blood flow velocity fluctuates due to, for example, heart pulsation, the blood flow velocity when both the first laser light and the second laser light are irradiated onto the blood may differ from the blood flow velocity when only one of the first laser light or the second laser light is irradiated onto the blood. In this case, when specifying the blood flow velocity, the blood flow velocity is specified based on two frequency spectra at different flow velocities, which may make it impossible to measure the blood flow velocity accurately. Therefore, this specification provides a technology that can measure the blood flow velocity accurately. [Means for solving the problem]

[0006] In a first aspect of the present technology, a measurement device includes an irradiation device that irradiates blood with a first laser light and a second laser light that intersects with the first laser light, a light receiving device that receives scattered light generated when at least one of the first laser light and the second laser light irradiated by the irradiation device hits the blood, and a processing device. The light receiving device outputs a light receiving signal corresponding to the received scattered light. The processing device samples a first light receiving signal that is a light receiving signal generated by scattered light generated when both the first laser light and the second laser light hit the blood, and a second light receiving signal that is a light receiving signal generated by scattered light generated when either the first laser light or the second laser light hits the blood, and outputs a first light receiving signal at an arbitrary time t n a first frequency spectrum, which is a frequency spectrum of the received light signal sampled at time t n time t earlier than n-1 a second frequency spectrum, which is a frequency spectrum of the received light signal sampled at time t n-1 time t earlier than n-2 and a third frequency spectrum, which is a frequency spectrum of the received light signal sampled at the time t n The light receiving signal sampled at time t n-1 The light receiving signal sampled at time t n-2 When the light receiving signal sampled at time t is the first light receiving signal, the first frequency spectrum, the second frequency spectrum, and the third frequency spectrum are used to calculate the light receiving signal at time t n-1 The processing device may estimate a fourth frequency spectrum, which is a frequency spectrum when it is assumed that the light receiving signal sampled at the time t is the first light receiving signal. n The light receiving signal sampled at time t n-1 The light receiving signal sampled at time t n-2 When the light receiving signal to be sampled at time t is the second light receiving signal, the first frequency spectrum, the second frequency spectrum, and the third frequency spectrum are used to calculate the light receiving signal at time t n-1A fifth frequency spectrum may be estimated, which is a frequency spectrum when it is assumed that the next sampled light receiving signal is the second light receiving signal.

[0007] According to this configuration, even if the blood flow velocity when both the first laser light and the second laser light are incident on the blood differs from the blood flow velocity when one of the first laser light and the second laser light is incident on the blood due to fluctuations in the blood flow velocity caused by, for example, heart pulsation, the blood flow velocity can be measured at multiple times t n , t n-1 , t n-2 Based on the frequency spectrum at time t n-1 By estimating the fourth frequency spectrum at the same time t n-1 It is possible to obtain the frequency spectrum of the first received light signal (the second frequency spectrum or the fourth frequency spectrum) and the frequency spectrum of the second received light signal (the second frequency spectrum or the fifth frequency spectrum) in the above-mentioned manner, thereby enabling the blood flow velocity to be measured with high accuracy.

[0008] In a second aspect, in the first aspect, the processing device may identify a Doppler shift frequency based on the second frequency spectrum and the fourth frequency spectrum or the fifth frequency spectrum, and identify a blood flow velocity based on the identified Doppler shift frequency.

[0009] According to this configuration, at the same time t n-1 The flow velocity of the blood being measured can be determined using the frequency spectrum of the first received light signal and the frequency spectrum of the second received light signal, thereby enabling the blood flow velocity to be measured with high accuracy.

[0010] In a third aspect, in the first or second aspect, the processing device may identify a point near the convergence value of the fourth frequency spectrum or a point near the convergence value of the fifth frequency spectrum based on a point near the convergence value of the second frequency spectrum.

[0011] According to this configuration, by specifying the points near the convergence value of each frequency spectrum, the fourth frequency spectrum or the fifth frequency spectrum can be accurately estimated.

[0012] In the fourth aspect of the present technology, the measuring device includes an irradiation device that irradiates blood with a first laser beam and a second laser beam that intersects the first laser beam, and a light receiving device that receives scattered light generated when the first laser beam and the second laser beam irradiated by the irradiation device hit the blood, and a processing device. The light receiving device outputs a light receiving signal corresponding to the received scattered light. The processing device generates a sixth frequency spectrum, which is the frequency spectrum of the light receiving signal due to the scattered light generated when both the first laser beam and the second laser beam hit the blood, based on the light receiving signal output by the light receiving device, and estimates a seventh frequency spectrum, which is the frequency spectrum of the light receiving signal due to the scattered light when it is assumed that one of the first laser beam or the second laser beam hits the blood, based on the generated sixth frequency spectrum.

[0013] According to this configuration, by estimating the seventh frequency spectrum based on the sixth frequency spectrum, even if the blood flow velocity fluctuates due to, for example, the pulsation of the heart, the blood flow velocity can be measured without being affected by the fluctuation. Thereby, the blood flow velocity can be accurately measured.

[0014] In the fifth aspect, in the fourth aspect described above, the processing device may specify a Doppler shift frequency based on the sixth frequency spectrum and the seventh frequency spectrum, and specify the blood flow velocity based on the specified Doppler shift frequency.

[0015] According to this configuration, the blood flow velocity can be accurately measured.

[0016] In the sixth aspect, in the fourth or fifth aspect described above, the processing device may estimate the seventh frequency spectrum based on a straight line connecting the peak point and the point near the convergence value of the sixth frequency spectrum.

[0017] According to this configuration, the seventh frequency spectrum can be accurately estimated.

Brief Description of the Drawings

[0018] [Figure 1] A diagram showing the schematic configuration of the measuring device of the embodiment. [Figure 2] A block diagram of the measuring device of the embodiment. [Figure 3] A flowchart of the first measurement process of Example 1. [Figure 4] A diagram (1) showing an example of the frequency spectrum of the received light signal. [Figure 5] A flowchart of the first estimation process of Example 1. [Figure 6] A diagram (2) showing an example of the frequency spectrum of the received light signal. [Figure 7] A flowchart of the second measurement process of Example 2. [Figure 8] A diagram (1) showing an example of the frequency spectrum of the received light signal. [Figure 9] A flowchart of the second estimation process of Example 2. [Figure 10] A diagram (2) showing an example of the frequency spectrum of the received light signal.

Modes for Carrying Out the Invention

[0019] The measuring device 1 of the embodiment will be described with reference to the drawings. As shown in FIG. 1, the measuring device 1 of the embodiment includes an irradiation device 2, a light receiving device 3, and a processing device 9. The measuring device 1 is a device for measuring the flow velocity of blood flowing inside the tube 100. The tube 100 is, for example, a human blood vessel. In a modified example, the tube 100 may be a blood vessel of an animal other than a human. In another modified example, the tube 100 may not be a blood vessel but an artificial resin tube or the like. In the measuring device 1 of the embodiment, the irradiation device 2, the light receiving device 3, and the processing device 9 are arranged inside the housing 8. Further, the tube 100 passes through the inside of the housing 8.

[0020] The irradiation device 2 is a device that irradiates the blood flowing inside the tube 100 with the first laser light L1 and the second laser light L2. The irradiation device 2 includes a light-emitting element 21, a collimator lens 22, a condenser lens 23, a spectroscope 24, a first mirror 41, a second mirror 42, and a light-shielding device 5.

[0021] The light-emitting element 21 is, for example, a laser diode (LD). The light-emitting element 21 is arranged to face the collimator lens 22 and emits laser light L toward the collimator lens 22. The laser light L emitted by the light-emitting element 21 enters the collimator lens 22. The laser light L emitted by the light-emitting element 21 is, for example, near-infrared light having a wavelength of about 850 nm to 1300 nm.

[0022] The collimator lens 22 is arranged between the light-emitting element 21 and the condenser lens 23. The collimator lens 22 emits the laser light L emitted by the light-emitting element 21 as parallel light. The laser light L (parallel light) emitted from the collimator lens 22 enters the condenser lens 23.

[0023] The condenser lens 23 is arranged between the collimator lens 22 and the spectroscope 24. The condenser lens 23 condenses and emits the laser light L (parallel light) emitted from the collimator lens 22. The laser light L emitted from the condenser lens 23 enters the spectroscope 24.

[0024] The spectroscope 24 is a device that splits the laser light L incident on the spectroscope 24 into the first laser light L1 and the second laser light L2. The first laser light L1 and the second laser light L2 generated by the spectroscope 24 travel in different directions from each other. In the example shown in FIG. 1, the first laser light L1 travels diagonally upward to the right, and the second laser light L2 travels diagonally upward to the left. The first laser light L1 travels toward the first mirror 41, and the second laser light L2 travels toward the second mirror 42. The wavelength of the first laser light L1 and the wavelength of the second laser light L2 are the same wavelength. Also, the frequency of the first laser light L1 and the frequency of the second laser light L2 are the same frequency.

[0025] The first mirror 41 and the second mirror 42 are disposed between the spectroscope 24 and the light blocking device 5. The first mirror 41 and the second mirror 42 face each other. The first laser light L1 generated by the spectroscope 24 is incident on the first mirror 41 and reflected therefrom. The second laser light L2 generated by the spectroscope 24 is incident on the second mirror 42 and reflected therefrom.

[0026] The first laser light L1 reflected by the first mirror 41 travels in a first direction D1. The second laser light L2 reflected by the second mirror 42 travels in a second direction D2. The first laser light L1 and the second laser light L2 travel in directions that intersect with each other (first direction D1 and second direction D2). The first laser light L1 and the second laser light L2 are each incident on the inside of the tube 100 through which blood flows. As a result, the first laser light L1 and the second laser light L2 are irradiated onto the blood flowing inside the tube 100. The first laser light L1 traveling in the first direction D1 and the second laser light L2 traveling in the second direction D2 intersect at an intersection 10 inside the tube 100. The first laser light L1 and the second laser light L2 overlap with each other inside the tube 100 and interfere with each other.

[0027] The shading device 5 is disposed between the mirrors (first mirror 41 and second mirror 42) and the tube 100. The shading device 5 can block the first laser light L1 and the second laser light L2 traveling toward the tube 100. The shading device 5 is configured to be switchable between a shading state in which it blocks either the first laser light L1 or the second laser light L2, and a non-shading state in which it does not block either the first laser light L1 or the second laser light L2. The shading states of the shading device 5 include a first shading state in which it blocks the first laser light L1 but does not block the second laser light L2, and a second shading state in which it blocks the second laser light L2 but does not block the first laser light L1. The configuration of the shading device 5 is not particularly limited as long as it is switchable between a shading state and a non-shading state.

[0028] The light-shielding device 5 includes, for example, a rotating body 52 disposed on the optical paths of the first laser beam L1 and the second laser beam L2. The rotating body 52 is disposed so as to cross the first laser beam L1 and the second laser beam L2. The rotating body 52 rotates at a predetermined rotational speed clockwise or counterclockwise by driving of a motor 54.

[0029] The rotating body 52 includes a light-shielding portion that shields the laser beam and a non-light-shielding portion that does not shield the laser beam (both are not shown). The non-light-shielding portion of the rotating body 52 is constituted by, for example, an opening provided in the rotating body 52, and is configured such that the laser beam (the first laser beam L1 and the second laser beam L2) can pass therethrough. On the other hand, the light-shielding portion is constituted by, for example, a portion of the rotating body 52 that is not the opening (non-light-shielding portion), and is configured such that the laser beam (the first laser beam L1 and the second laser beam L2) cannot pass therethrough. In the light-shielding device 5, the positions of the light-shielding portion and the non-light-shielding portion are switched as the rotating body 52 rotates.

[0030] In the measuring device 1 shown in FIG. 1, in the first light-shielded state (a state in which the first laser beam L1 is shielded while the second laser beam L2 is not shielded), the second laser beam L2 enters the inside of the tube 100. Further, in the second light-shielded state (a state in which the second laser beam L2 is shielded while the first laser beam L1 is not shielded), the first laser beam L1 enters the inside of the tube 100. Further, in the non-light-shielded state (a state in which neither the first laser beam L1 nor the second laser beam L2 is shielded), both the first laser beam L1 and the second laser beam L2 enter the inside of the tube 100.

[0031] The first laser beam L1 and / or the second laser beam L2 that has entered the inside of the tube 100 scatters when it hits the blood flowing inside the tube 100. More specifically, the first laser beam L1 and / or the second laser beam L2 scatters when it hits the red blood cells contained in the blood. Thereby, scattered light is generated. The first laser beam L1 and the second laser beam L2 hit the blood from different directions. The first laser beam L1 travels in the first direction D1 and hits the blood. The second laser beam L2 travels in the second direction D2 and hits the blood.

[0032] In the measuring device 1, when the first laser light L1 and / or the second laser light L2 strikes blood and scatters, the frequency of each laser light L1, L2 changes due to Doppler shift. The frequency of the scattered light generated by the scattering of each laser light L1, L2 is different from the frequency of each laser light L1, L2. The scattered light generated by the scattering of each laser light L1, L2 travels in various directions. Of the scattered light generated by the scattering of each laser light L1, L2, scattered light P traveling toward the light-receiving device 3 is received by the light-receiving device 3.

[0033] The light receiving device 3 is disposed so as to face the tube 100 through which blood flows. The light receiving device 3 is equipped with a light receiving element 31 that receives scattered light P. The light receiving element 31 is, for example, a photodiode (PD). Of the scattered light generated by scattering of the laser beams L1 and L2, the scattered light P traveling toward the light receiving device 3 is incident on the light receiving element 31. When the light receiving element 31 receives the scattered light P, it outputs a light receiving signal corresponding to the intensity of the scattered light P. As a result, a light receiving signal corresponding to the intensity of the scattered light P is transmitted from the light receiving device 3 to the processing device 9. The light receiving device 3 outputs the light receiving signal in the form of a voltage signal. In a modified example, the light receiving device 3 may output the light receiving signal in the form of a current signal.

[0034] As shown in FIG. 2, the processing device 9 of the measuring device 1 is electrically connected to the irradiation device 2 and the light receiving device 3. The processing device 9 includes, for example, a processing unit 92 and a memory unit 94. The processing unit 92 includes, for example, a CPU, and executes various controls and processes related to the measuring device 1 based on a predetermined program. For example, the processing unit 92 calculates the flow velocity of blood flowing inside the tube 100. The processing unit 92 calculates the blood flow velocity using a calculation method based on the Doppler shift. The memory unit 94 includes, for example, a ROM and a RAM, and stores various information related to the measuring device 1.

[0035] Example 1 (First measurement process; Figure 3) Next, the first measurement process of Example 1 will be described with reference to FIG. 3. The first measurement process is started, for example, when the light-emitting element 21 of the irradiation device 2 emits the laser light L. The start trigger of the first measurement process is not particularly limited. As shown in FIG. 3, in S2 of the first measurement process, the processing device 9 samples the light reception signal output by the light reception device 3 at a predetermined time interval (for example, 1-second interval). The time interval of sampling is preferably the same time interval as, for example, the time interval at which the light shielding state and the non-light shielding state of the light shielding device 5 are switched. The processing device 9 alternately samples the light reception signal (first light reception signal) when the light shielding device 5 is in the non-light shielding state and the light reception signal (second light reception signal) when the light shielding device 5 is in the light shielding state (first light shielding state or second light shielding state).

[0036] When the light shielding device 5 is in the non-light shielding state, both the first laser light L1 and the second laser light L2 are irradiated onto the blood from the irradiation device 2. Therefore, the first light reception signal when the light shielding device 5 is in the non-light shielding state is a light reception signal due to scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood.

[0037] On the other hand, when the light shielding device 5 is in the light shielding state (first light shielding state or second light shielding state), one of the first laser light L1 or the second laser light L2 is irradiated onto the blood from the irradiation device 2. Therefore, the second light reception signal when the light shielding device 5 is in the light shielding state (first light shielding state or second light shielding state) is a light reception signal due to scattered light generated when one of the first laser light L1 or the second laser light L2 hits the blood.

[0038] In the measuring device 1, for example, the light reception signal sampled by the processing device 9 at an arbitrary time t n is the first light reception signal based on the scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood (however, n is a natural number of 1 or more). Also, the processing device 9 samples at time t n at a time t one before that n-1The received light signal to be sampled is a second received light signal based on scattered light generated when either the first laser light L1 or the second laser light L2 hits the blood. Also, at time t, the processing device 9 n-1 at the time t one before n-2 The received light signal to be sampled is a first received light signal based on scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood.

[0039] In the subsequent S4, the processing device 9 generates the frequency spectrum of the received light signal sampled in the above S2. More specifically, the processing device 9 performs a Fourier transform on the received light signal sampled in S2. The processing device 9 can perform a Fourier transform, for example, by means of an FFT (Fast Fourier Transform) analyzer. Fourier transform is a technique that can convert a function of time into a function of frequency. Since Fourier transform is well known, a detailed description thereof will be omitted. The processing device 9 generates the frequency spectrum of the received light signal by performing a Fourier transform. Also, the processing device 9 converts the generated frequency spectrum into decibels. The frequency spectrum converted into decibels is shown, for example, as the relationship between frequency and voltage as shown in FIG. 4.

[0040] In S4, the processing device 9 n for the received light signal (first received light signal) sampled at time t n-1 for the received light signal (second received light signal) sampled at time t n-2 and for each of the received light signals (first received light signals) sampled at time t n generates a frequency spectrum. By S4, the frequency spectra of the received light signals sampled at a predetermined time interval (for example, 1-second interval) are generated. For example, as shown in FIG. 4, the frequency spectrum (first frequency spectrum) SP(t n ) of the received light signal (first received light signal) sampled at time t n-1 the frequency spectrum (second frequency spectrum) SP(t n-1 ) of the received light signal (second received light signal) sampled at time t n-2The frequency spectrum (third frequency spectrum) SP(t n-2 ) is generated.

[0041] In S4, at time t n The first frequency spectrum SP(t n ) is the frequency spectrum of the first received light signal due to scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood. n-2 The third frequency spectrum SP(t n-2 ) is the frequency spectrum of the first received light signal due to scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood. n-1 The second frequency spectrum SP(t n-1 ) is the frequency spectrum of the second received light signal due to scattered light generated when either the first laser light L1 or the second laser light L2 hits the blood.

[0042] In the next step S6, the processing device 9 n The first frequency spectrum SP(t n ), time t n-1 The second frequency spectrum SP(t n-1 ), and time t n-2 The third frequency spectrum SP(t n-2 ) based on the fourth frequency spectrum SPX(t n-1 ) is estimated. n-1 ) at time t n-1 1 is a frequency spectrum when it is assumed that the light receiving signal sampled at time t n-1 The light receiving signal sampled in is the second light receiving signal (i.e., the light receiving signal due to scattered light generated when either the first laser light L1 or the second laser light L2 hits the blood), but the fourth frequency spectrum SPX(t n-1 ) is virtually at time t n-1When it is assumed that the received light signal to be sampled is not the second received light signal but the first received light signal (i.e., the received light signal due to the scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood), the time t n-1 is the frequency spectrum at. The processing device 9 executes a first estimation process (see FIG. 5) to estimate the fourth frequency spectrum SPX(t n-1 ).

[0043] (First Estimation Process; FIG. 5) Next, the first estimation process of Example 1 will be described with reference to FIG. 5. As shown in FIG. 5, in S62 of the first estimation process, the processing device 9 identifies the points near the convergence value in each frequency spectrum. As shown in FIG. 6, in the frequency spectrum of the received light signal, as it goes from the peak point toward the high-frequency side (the right side of the X-axis), the value on the Y-axis (voltage axis) decreases and converges to a certain value. The point near the convergence value is a point near the convergence value in the frequency spectrum. The point near the convergence value is, for example, a point where the value on the Y-axis in the frequency spectrum becomes 115% of the convergence value. Note that the value of the point near the convergence value is not particularly limited.

[0044] In S62, the processing device 9 determines the time t n identifies the point V(t n ) near the convergence value in the first frequency spectrum SP(t n ) at. Similarly, the processing device 9 determines the time t n-1 identifies the point V(t n-1 ) near the convergence value in the second frequency spectrum SP(t n-1 ) at. Also, the processing device 9 determines the time t n-2 identifies the point V(t n-2 ) near the convergence value in the third frequency spectrum SP(t n-2 ) at. Note that the point V(t n-1 ) near the convergence value in the second frequency spectrum SP(t n-1 ) at, for example, the time t n-1 is such that in the second frequency spectrum SP(t n-1 ) at the time t n-1 , the value on the Y-axis is the time t n in the first frequency spectrum SP(t n) may be a point that is 115% of the convergence value in

[0045] In subsequent S64, the processing device 9 determines a point near the specific convergence value VX(t n-1 ) for specifying the fourth frequency spectrum SPX(t n-1 ). More specifically, the processing device 9 multiplies the value of the X-axis coordinate (frequency-axis coordinate) of the point V(t n-1 ) near the convergence value in the second frequency spectrum SP(t n-1 ) at time t n-1 ) by a predetermined coefficient (for example, 0.9) to determine the point VX(t n-1 ) near the specific convergence value (see FIG. 6). The point VX(t n-1 ) near the specific convergence value is a point obtained by translating the point V(t n-1 ) near the convergence value in the second frequency spectrum SP(t n-1 ) at time t n-1 ) in the negative direction of the X-axis.

[0046] In subsequent S66, the processing device 9 determines the deviation width in the X-axis (frequency-axis) direction from other points near the convergence value for the point VX(t n-1 ) near the specific convergence value determined in the above S64. More specifically, the processing device 9 determines the deviation width α in the X-axis direction between the point VX(t n-1 ) near the specific convergence value and the point V(t n-2 ) near the convergence value in the third frequency spectrum SP(t n-2 ) at time t n-2 ) (see FIG. 6). Further, the processing device 9 determines the deviation width β in the X-axis direction between the point VX(t n-1 ) near the specific convergence value and the point V(t n ) near the convergence value in the first frequency spectrum SP(t n ) at time t n ).

[0047] In subsequent S68, the processing device 9 estimates the fourth frequency spectrum SPX(t n-1 ) using the deviation widths α and β determined in the above S66. More specifically, the processing device 9 estimates the fourth frequency spectrum SPX(tn-1 ) is calculated. The processing device 9 calculates at time t n 's first frequency spectrum SP(t n ), at time t n-2 's third frequency spectrum SP(t n-2 ), and based on the deviation widths α, β, calculates the fourth frequency spectrum SPX(t n-1 ). The processing device 9 calculates the fourth frequency spectrum SPX(t n-1 ) according to the following formula (1). The processing device 9 executes the calculation according to formula (1) for a plurality of points of each frequency spectrum.

[0048]

Equation

[0049] When the first estimation process (see FIG. 5) is completed, the processing device 9 executes S8 of the first measurement process (see FIG. 3). In S8 of the first measurement process, the processing device 9 determines the Doppler shift frequency fd based on the fourth frequency spectrum SPX(t n-1 ) estimated in the first estimation process (see FIG. 5) and the second frequency spectrum SP(t n-1 ) at time t n-1 . More specifically, the processing device 9 calculates the Doppler shift frequency fd based on the peak frequency fpX in the fourth frequency spectrum SPX(t n-1 ) and the peak frequency fp(t n-1 ) in the second frequency spectrum SP(t n-1 ) at time t n-1 . Note that the peak frequency is the frequency (value on the X-axis) corresponding to the maximum value of the voltage (value on the Y-axis) in the frequency spectrum. The processing device 9 determines the Doppler shift frequency fd, for example, according to the following formula (2).

[0050]

Equation

[0051] In the next step S10, the processing device 9 determines the flow velocity v of the blood being measured (blood flowing through the tube 100) based on the Doppler shift frequency fd determined in S8 above. The processing device 9 determines the blood flow velocity v, for example, based on the following equation (3). In the following equation (3), λ is the wavelength of the first laser light L1 and the second laser light L2, and θ is half the intersection angle between the first laser light L1 and the second laser light L2 (see FIG. 1). The processing device 9 also determines the blood flow rate based on the determined blood flow velocity v. For example, the processing device 9 determines the blood flow rate by multiplying the determined blood flow velocity v by the cross-sectional area of the tube 100. Note that the processing device 9 may determine the blood flow velocity and flow rate using other calculation methods. The calculation method is not particularly limited.

[0052]

number

[0053] The measuring device 1 of the first embodiment has been described above. As is clear from the above description, the processing device 9 n The first frequency spectrum SP(t n ) and time t n-1 The second frequency spectrum SP(t n-1 ) and time t n-2 The third frequency spectrum SP(t n-2 ) and based on time t n-1 The fourth frequency spectrum SPX(t n-1 ) is estimated (see S6 in Figure 3 and Figure 5).

[0054] According to this configuration, even if the blood flow velocity when both the first laser light L1 and the second laser light L2 hit the blood differs from the blood flow velocity when one of the first laser light L1 or the second laser light L2 hits the blood due to fluctuations in the blood flow velocity caused by, for example, heart pulsation, the blood flow velocity can be measured at multiple times t n , t n-1 , tn-2 Based on the frequency spectrum at time t n-1 the fourth frequency spectrum SPX(t n-1 ) at time t is estimated, and the fourth frequency spectrum SPX(t n-1 ) of the first received signal and the second frequency spectrum SP(t n-1 ) of the second received signal at the same time t n-1 ) can be obtained. Thereby, the blood flow velocity v can be accurately measured.

[0055] Further, the processing device 9 identifies the Doppler shift frequency fd based on the second frequency spectrum SP(t n-1 ) and the fourth frequency spectrum SPX(t n-1 ), and identifies the blood flow velocity v based on the identified Doppler shift frequency fd (see S8 and S10 in FIG. 3).

[0056] According to this configuration, the blood flow velocity v of the measurement target can be identified using the fourth frequency spectrum SPX(t n-1 ) of the first received signal and the second frequency spectrum SP(t n-1 ) of the second received signal at the same time t n-1 ). Thereby, the blood flow velocity v can be accurately measured.

[0057] When the processing device 9 estimates the fourth frequency spectrum SPX(t n-1 ), it identifies a specific convergence value vicinity point VX(t n-1 ) of the fourth frequency spectrum SPX(t n-1 ) based on a point V(t n-1 ) near the convergence value of the second frequency spectrum SP(t n-1 ) (see FIG. 6). According to this configuration, the fourth frequency spectrum SPX(t n-1 ) can be accurately estimated.

[0058] (Modification example) In the above-described Example 1, the processing device 9 at time t nThe received light signal to be sampled is the first received light signal (i.e., the received light signal based on the scattered light generated when both the first laser beam L1 and the second laser beam L2 hit the blood), but it is not limited to this configuration. Also, at time t, the processing device 9 n-1 The received light signal to be sampled is the second received light signal (i.e., the received light signal based on the scattered light generated when either the first laser beam L1 or the second laser beam L2 hits the blood), and at time t n-2 The received light signal to be sampled is the first received light signal (i.e., the received light signal based on the scattered light generated when both the first laser beam L1 and the second laser beam L2 hit the blood), but it is not limited to this configuration.

[0059] In a modified example, at time t, the processing device 9 n The received light signal to be sampled may be the second received light signal (i.e., the received light signal based on the scattered light generated when either the first laser beam L1 or the second laser beam L2 hits the blood). Also, at time t, the processing device 9 n-1 The received light signal to be sampled is the first received light signal (i.e., the received light signal based on the scattered light generated when both the first laser beam L1 and the second laser beam L2 hit the blood), and at time t n-2 The received light signal to be sampled may be the second received light signal (i.e., the received light signal based on the scattered light generated when either the first laser beam L1 or the second laser beam L2 hits the blood).

[0060] In this case, at time t n The first frequency spectrum SP(t n ) is the frequency spectrum of the second received light signal, and at time t n-1 The second frequency spectrum SP(t n-1 ) is the frequency spectrum of the first received light signal, and at time t n-2 The third frequency spectrum SP(t n-2 ) is the frequency spectrum of the second received light signal.

[0061] Also, in S6 of the first measurement process (see FIG. 3), the processing device 9, at time t nThe first frequency spectrum SP(t n ), at time t n-1 The second frequency spectrum SP(t n-1 ), and at time t n-2 The third frequency spectrum SP(t n-2 ), based on this, the fifth frequency spectrum SPX(t n-1 ) is estimated. The fifth frequency spectrum SPX(t n-1 ) is the frequency spectrum when it is assumed that the received light signal sampled at time t n-1 is the second received light signal. In a modified example, the received light signal sampled at time t n-1 is the first received light signal (that is, the received light signal based on the scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood), but the fifth frequency spectrum SPX(t n-1 ) is virtually the frequency spectrum at time t n-1 when it is assumed that the received light signal sampled at time t n-1 is not the first received light signal but the second received light signal (that is, the received light signal based on the scattered light generated when one of the first laser light L1 or the second laser light L2 hits the blood).

[0062] The processing device 9 executes a first estimation process to estimate the fifth frequency spectrum SPX(t n-1 ) (see FIG. 5). Since the first estimation process is the same as that in the first embodiment, a detailed description thereof is omitted. Also, for S8 and S10 of the first measurement process (see FIG. 3), since they are the same as those in the first embodiment, a detailed description thereof is omitted. In the first estimation process and the first measurement process of the modified example, "the fourth frequency spectrum" is read as "the fifth frequency spectrum".

[0063] According to the configuration of the modified example, based on the frequency spectra at a plurality of times t n , t n-1 , t n-2 , the fifth frequency spectrum SPX(t n-1 ) at time t n-1 ) is estimated, so that the fifth frequency spectrum SPX(t n-1 ) of the second received light signal at the same time tn-1 ) and the second frequency spectrum SP(t of the first received optical signal n-1 ) can be obtained. Thus, similar to Example 1, the blood flow velocity v can be accurately measured.

[0064] (Example 2) Next, Example 2 will be described. In the description of Example 2, detailed descriptions of configurations similar to those in the above Example 1 may be omitted.

[0065] (Second measurement process; FIG. 7) The second measurement process of Example 2 will be described with reference to FIG. 7. The second measurement process is started, for example, when the light emitting element 21 of the irradiation device 2 emits the laser light L. The start trigger of the second measurement process is not particularly limited. As shown in FIG. 7, in S2 of the second measurement process, the processing device 9 samples the received optical signal output by the light receiving device 3 at a predetermined time interval (for example, 1 second interval). The process of S2 in the second measurement process is the same as the process of S2 in the first measurement process (see FIG. 3). Therefore, detailed description of the process of S2 in the second measurement process will be omitted.

[0066] In S24 following S2 of the second measurement process, the processing device 9 generates a sixth frequency spectrum SP6, which is the frequency spectrum of the first received optical signal (that is, the received optical signal based on the scattered light generated when both the first laser light L1 and the second laser light L2 hit the blood), among the received optical signals sampled in S2 above. The processing device 9 generates the sixth frequency spectrum SP6 by performing a Fourier transform on the first received optical signal sampled in S2. The processing device 9 can perform the Fourier transform by, for example, an FFT (Fast Fourier Transform) analyzer. Since the Fourier transform is well known, detailed description thereof will be omitted. Further, the processing device 9 converts the generated sixth frequency spectrum SP6 into decibels. The sixth frequency spectrum SP6 converted into decibels is shown, for example, as the relationship between frequency and voltage as shown in FIG. 8.

[0067] In subsequent S26, the processing device 9 estimates a seventh frequency spectrum SP7 based on the sixth frequency spectrum SP6 generated in the above S24. The seventh frequency spectrum SP7 is the frequency spectrum of the received signal due to scattered light when it is assumed that either the first laser beam L1 or the second laser beam L2 hits the blood. The sixth frequency spectrum SP6 and the seventh frequency spectrum SP7 are regarded as the frequency spectra of the received signal due to scattered light at the same time. The processing device 9 executes a second estimation process (see FIG. 9) to estimate the seventh frequency spectrum SP7.

[0068] (Second Estimation Process; FIG. 9) Next, the second estimation process of the second embodiment will be described with reference to FIG. 9. As shown in FIG. 9, in S82 of the second estimation process, the processing device 9 identifies a peak point Z and a point V near the convergence value in the sixth frequency spectrum SP6 (see FIG. 10). As shown in FIG. 10, the peak point Z in the sixth frequency spectrum SP6 is the point at which the voltage value (value on the Y-axis) is maximum in the sixth frequency spectrum SP6. Also, in the sixth frequency spectrum SP6, as it goes from the peak point Z toward the high-frequency side (right side of the X-axis), the voltage value (value on the Y-axis) decreases and converges to a certain value. The point V near the convergence value of the sixth frequency spectrum SP6 is a point near the convergence value in the sixth frequency spectrum SP6. The point V near the convergence value is, for example, the point at which the voltage value (value on the Y-axis) is 115% of the convergence value in the sixth frequency spectrum SP6. Note that the point V near the convergence value is not particularly limited.

[0069] In subsequent S84, the processing device 9 identifies a first straight line M1 which is a straight line connecting the peak point Z of the sixth frequency spectrum SP6 and the vicinity point V of the convergence value (see FIG. 10). In subsequent S86, the processing device 9 identifies a second straight line M2, a third straight line M3, and a fourth straight line M4 (see FIG. 10). The second straight line M2 is a straight line passing through the peak point Z of the sixth frequency spectrum SP6, and its slope is a slope obtained by multiplying the slope of the first straight line M1 by a predetermined coefficient. The predetermined coefficient is obtained in advance, for example, by performing a regression analysis on the experimental results obtained through prior experiments. The third straight line M3 is a straight line obtained by translating the second straight line M2 in the negative direction of the Y-axis by a predetermined value. The predetermined value is obtained in advance, for example, by performing a regression analysis on the experimental results obtained through prior experiments. The fourth straight line M4 is a straight line parallel to the X-axis, and the value of the Y-axis is a value less than the convergence value of the sixth frequency spectrum SP6.

[0070] In subsequent S88, the processing device 9 estimates the seventh frequency spectrum SP7. The processing device 9 sets the line connecting the third straight line M3 and the fourth straight line M4 identified in the above S86 as the seventh frequency spectrum SP7 (see FIG. 10). The seventh frequency spectrum SP7 is regarded as the frequency spectrum of the received light signal due to the scattered light generated when either the first laser beam L1 or the second laser beam L2 hits the blood.

[0071] When the second estimation process (see FIG. 9) ends, the processing device 9 executes S28 of the second measurement process (see FIG. 7). In S28 of the second measurement process, the processing device 9 identifies the Doppler shift frequency fd based on the sixth frequency spectrum SP6 generated in the above S24 and the seventh frequency spectrum SP7 estimated in the second estimation process (see FIG. 9). More specifically, the processing device 9 calculates the Doppler shift frequency fd based on the peak frequency fp6 in the sixth frequency spectrum SP6 and the peak frequency fp7 in the seventh frequency spectrum SP7. Note that the peak frequency is the frequency (value on the X-axis) corresponding to the maximum value of the voltage (value on the Y-axis) in the frequency spectrum. The processing device 9 identifies the Doppler shift frequency fd, for example, by the following formula (4).

[0072]

Number

[0073] In the subsequent S10, the processing device 9 specifies the flow velocity v of the blood to be measured (the blood flowing through the tube 100) based on the Doppler shift frequency fd specified in the above S28. The processing device 9 specifies the flow velocity v of the blood, for example, based on the above-described formula (3). The processing in S10 of the second measurement process is the same as the processing in S10 of the first measurement process (see FIG. 3). Therefore, the detailed description of the processing in S10 of the second measurement process is omitted.

[0074] As described above, the measuring device 1 of the second embodiment has been described. As is clear from the above description, the processing device 9 generates the sixth frequency spectrum SP6, which is the frequency spectrum of the received light signal due to the scattered light generated when both the first laser beam L1 and the second laser beam L2 hit the blood, and based on the generated sixth frequency spectrum SP6, estimates the seventh frequency spectrum SP7, which is the frequency spectrum of the received light signal due to the scattered light when it is assumed that either the first laser beam L1 or the second laser beam L2 hits the blood.

[0075] The processing device 9 specifies the Doppler shift frequency fd based on the sixth frequency spectrum SP6 and the seventh frequency spectrum SP7, and specifies the flow velocity v of the blood based on the specified Doppler shift frequency fd.

[0076] According to this configuration, by estimating the seventh frequency spectrum SP7 based on the sixth frequency spectrum SP6, even if the flow velocity of the blood fluctuates due to, for example, the pulsation of the heart, the flow velocity of the blood can be measured without being affected by the fluctuation. Thereby, the flow velocity of the blood can be measured with high accuracy.

[0077] The processing device 9 estimates the seventh frequency spectrum SP7 based on the first straight line M1 connecting the peak point Z of the sixth frequency spectrum SP6 and the convergence value neighborhood point V. With this configuration, the seventh frequency spectrum SP7 can be estimated with high accuracy.

[0078] (Variation) In the above-described first and second embodiments, the light blocking device 5 is configured to block the first laser light L1 and the second laser light L2, but is not limited to this configuration. In a modified example, the light blocking device 5 may be configured to block only the first laser light L1 and not the second laser light L2. In another modified example, the light blocking device 5 may be configured to block only the second laser light L2 and not the first laser light L1.

[0079] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0080] 1: measuring device, 2: irradiation device, 3: light receiving device, 5: light blocking device, 8: housing, 9: processing device, 10: intersection, 21: light emitting element, 22: collimator lens, 23: condenser lens, 24: spectroscope, 31: light receiving element, 41: first mirror, 42: second mirror, 52: rotating body, 54: motor, 100: tube, L1: first laser light, L2: second laser light

Claims

1. An irradiation device that irradiates blood with a first laser beam and a second laser beam that intersects the first laser beam, A light receiving device that receives scattered light generated when at least one of the first laser beam and the second laser beam irradiated by the irradiation device hits the blood, A processing device, and The light receiving device outputs a light receiving signal corresponding to the received scattered light, The processing device, A first light receiving signal that is a light receiving signal due to scattered light generated when both the first laser beam and the second laser beam hit the blood, and a second light receiving signal that is a light receiving signal due to scattered light generated when only one of the first laser beam or the second laser beam hits the blood are sampled, Any time t ｎ a first frequency spectrum that is the frequency spectrum of the received signal sampled at time t, the time t ｎ at a time t earlier than ｎ－１ a second frequency spectrum that is the frequency spectrum of the received signal sampled at time t, the time t ｎ－１ at a time t earlier than ｎ－２ a third frequency spectrum that is the frequency spectrum of the received signal sampled at time t, and generate the time t ｎ the received light signal sampled at the time t is the first received light signal, and the time t ｎ－１ the received light signal sampled at the time t is the second received light signal, and the time t ｎ－２ when the received light signal sampled at the time t is the first received light signal, based on the first frequency spectrum, the second frequency spectrum, and the third frequency spectrum, estimate a fourth frequency spectrum that is the frequency spectrum when it is assumed that the received light signal sampled at the time t ｎ－１ is the first received light signal, the time t ｎ the received light signal sampled at the time t is the second received light signal, and the time t ｎ－１ the received light signal sampled at the time t is the first received light signal, and the time t ｎ－２ when the received light signal sampled at the time t is the second received light signal, based on the first frequency spectrum, the second frequency spectrum, and the third frequency spectrum, the time t ｎ－１ a measuring device that estimates a fifth frequency spectrum that is a frequency spectrum when it is assumed that the received light signal sampled at the time t is the second received light signal.

2. The processing device specifies a Doppler shift frequency based on the second frequency spectrum and the fourth frequency spectrum or the fifth frequency spectrum, and specifies the blood flow velocity based on the specified Doppler shift frequency. The measuring device according to claim 1.

3. The processing device specifies a point near the convergence value of the fourth frequency spectrum or a point near the convergence value of the fifth frequency spectrum based on a point near the convergence value of the second frequency spectrum. The measuring device according to claim 1 or 2.

4. An irradiation device that irradiates blood with a first laser beam and a second laser beam that intersects the first laser beam, A light receiving device that receives scattered light generated when the first laser beam and the second laser beam irradiated by the irradiation device hit the blood, A processing device, and The light receiving device outputs a light receiving signal corresponding to the received scattered light, The processing device, Based on the light receiving signal output by the light receiving device, a sixth frequency spectrum that is a frequency spectrum of a light receiving signal due to scattered light generated when both the first laser beam and the second laser beam hit the blood is generated, Based on the generated sixth frequency spectrum, a seventh frequency spectrum that is a frequency spectrum of a light receiving signal due to scattered light assuming that only one of the first laser beam or the second laser beam hits the blood is estimated. Measuring device.

5. The processing device specifies a Doppler shift frequency based on the sixth frequency spectrum and the seventh frequency spectrum, and specifies the blood flow velocity based on the specified Doppler shift frequency. The measuring device according to claim 4.

6. The measuring device according to claim 4 or 5, wherein the processing device estimates the seventh frequency spectrum based on a straight line connecting a peak point of the sixth frequency spectrum and a point near the convergence value.

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