Method for estimating liquid flow state and liquid flow state estimation system

Abstract

This method for estimating the fluid state of a liquid has a step (a) for applying heat to a liquid, a step (b) for acquiring a temperature distribution of the liquid to which heat was applied, and a step (c) for estimating the fluid state of the liquid on the basis of the acquired temperature distribution. In addition, this system for estimating the fluid state of a liquid comprises a heating means 1 that applies heat to a liquid, a temperature distribution acquisition means 2 that acquires a temperature distribution of the liquid to which heat was applied, and an estimation means 3 that estimates the fluid state of the liquid on the basis of the acquired temperature distribution. Employing such a method and system for estimating the fluid state of a liquid makes it possible to estimate the flow of the liquid in a non-invasive manner.

Description

Technical Field

[0001] The present invention relates to a method and a system for estimating the flow state of a liquid.

Background Art

[0002] Aqueous humor supplies nutrients to tissues without blood vessels in the eye, removes waste products, and plays a role in adjusting intraocular pressure. Usually, the intraocular pressure is kept constant by a circulation in which the aqueous humor produced in the eye passes through the trabecular meshwork and is discharged outside the eye through the Schlemm's canal. However, when the trabecular meshwork becomes clogged, the fluidity and drainage function of the aqueous humor decrease, and the intraocular pressure increases. An increase in intraocular pressure is known as one of the main mechanisms of glaucoma onset, and symptoms such as compression of the optic nerve, resulting in a decrease in visual function, a narrowing of the visual field, and a decrease in visual acuity, appear. Therefore, understanding the flow of aqueous humor in the eye is important for the early detection and treatment of glaucoma.

[0003] As a technique for understanding the flow of aqueous humor in the eye, for example, Patent Document 1 discloses locally administering a traceable component such as a dye or a fluorescent substance to the aqueous humor and visualizing and monitoring the flow of the aqueous humor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technique disclosed in Patent Document 1, it is necessary to use a syringe or the like to administer a traceable component to the aqueous humor. Considering the administration to the aqueous humor in the eye, it is not desirable from the viewpoint of invasiveness.

[0006] In addition to the flow of aqueous humor in the eye, there are various fields with a need to non-invasively grasp very weak liquid flows (micro-flows) or invisible liquid flows. For example, specific needs include grasping the state of water or oil flow to detect the presence or absence of water or oil leakage and its cause location, grasping the state of blood flow in the human body, and verifying the processing accuracy of micro-channels.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a method for estimating a liquid flow state and a liquid flow state estimation system that can non-invasively estimate the liquid flow state.

Means for Solving the Problems

[0008] In order to achieve the above object, first, the present invention provides a method for estimating a liquid flow state having a step (a) of applying heat to a liquid, a step (b) of acquiring a temperature distribution of the liquid to which heat has been applied, and a step (c) of estimating the liquid flow state based on the acquired temperature distribution (Invention 1).

[0009] According to the above invention (Invention 1), by taking advantage of the property that heat can be applied to the liquid non-invasively and estimating the liquid flow state by grasping the temperature distribution of the liquid to which heat has been applied, the liquid flow state can be estimated non-invasively.

[0010] In the above invention (Invention 1), in step (b), a plurality of temperature distributions of the liquid at different times may be acquired, and in step (c), the liquid flow state may be estimated based on the plurality of acquired temperature distributions (Invention 2).

[0011] According to the above invention (Invention 2), by comprehensively estimating the liquid flow state based on a plurality of temperature distributions, the estimation accuracy can be improved compared to estimating the liquid flow state from a single temperature distribution.

[0012] In the above inventions (Inventions 1 and 2), it is preferable that step (c) includes: step (c1) of setting two positions that form a pair within the region where the temperature distribution has been obtained, and obtaining the temperature difference or temperature ratio between the two positions; step (c2) of executing step (c1) a plurality of times, and selecting one pair having the maximum temperature difference or temperature ratio from among a plurality of pairs of the two positions within the region where the temperature distribution has been obtained; and step (c3) of estimating the direction from the position on the lower temperature side to the position on the higher temperature side among the two positions constituting the selected one pair as the direction in which the liquid flows (Invention 3).

[0013] In the above invention (Invention 3), step (c) may further include step (c4) of estimating the flow rate of the liquid from the temperature difference or temperature ratio between the two positions constituting the one pair selected in step (c2) (Invention 4).

[0014] In the above inventions (Inventions 1 to 4), in step (c), the region where the temperature distribution has been obtained may be divided into a plurality of unit regions, and the flow state of the liquid may be estimated based on the temperatures of the plurality of unit regions (Invention 5).

[0015] In the above invention (Invention 5), the temperature of one of the unit regions may be calculated as the average value of the temperature of the one unit region determined by the temperature distribution and the temperature of another unit region adjacent to the one unit region (Invention 6).

[0016] In the above inventions (Inventions 1 to 6), in step (b), at least one of the temperature distribution of the liquid during the heating period in which heat is applied to the liquid and the temperature distribution of the liquid during the cooling period after the application of heat to the liquid is stopped is obtained, and in step (c), the flow state of the liquid may be estimated based on at least one of the temperature distribution during the heating period and the temperature distribution during the cooling period (Invention 7).

[0017] In the above inventions (Inventions 1 to 7), in step (a), heat may be applied to the liquid by irradiating the liquid with light from a light source (Invention 8).

[0018] In the above inventions (Inventions 1 to 8), in step (b), the temperature distribution of the liquid may be obtained by photographing the liquid with a thermographic camera (Invention 9).

[0019] Second, the present invention provides a liquid flow state estimation system including a heating means for applying heat to a liquid, a temperature distribution acquisition means for acquiring the temperature distribution of the heated liquid, and an estimation means for estimating the flow state of the liquid based on the acquired temperature distribution (Invention 10).

Effect of the Invention

[0020] According to the liquid flow state estimation method and the liquid flow state estimation system according to the present invention, by taking advantage of the property that heat can be applied to the liquid in a non-invasive manner, and estimating the flow state of the liquid by grasping the temperature distribution of the liquid to which heat has been applied, it is possible to estimate the flow state of the liquid in a non-invasive manner.

Brief Description of the Drawings

[0021]

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Mode for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below are examples, and the present invention is not limited to these embodiments.

[0023] In the present embodiment, a case where the liquid flow state estimation system 100 estimates the flow state of the aqueous humor of the eye E to be examined will be described as an example. The flow state of the aqueous humor is a concept including the presence or absence of the flow of the aqueous humor, the direction of the flow of the aqueous humor, and its flow velocity. In the present embodiment, the liquid flow state estimation system 100 confirms the presence or absence of the flow of the aqueous humor and estimates the direction of the flow of the aqueous humor and its flow velocity.

[0024] As shown in FIG. 1, the liquid flow state estimation system 100 according to the present embodiment includes a light source 1 that irradiates the eye to be examined E with near-infrared light to apply heat to the aqueous humor of the eye to be examined E, a thermographic camera 2 that photographs the eye to be examined E in order to acquire the temperature distribution of the aqueous humor of the eye to be examined E to which heat has been applied by the light source 1, and an estimation device 3 that estimates the flow state of the aqueous humor from the acquired temperature distribution information of the aqueous humor (the photographed temperature distribution image).

[0025] As the light source 1 used for applying heat to the aqueous humor of the eye to be examined E in the present embodiment, for example, a halogen lamp (halogen heater) capable of irradiating near-infrared light can be used. By continuously irradiating the eye to be examined E with near-infrared light from the light source 1 for a predetermined time, for example, 20 seconds, the near-infrared light passes through the cornea of the eye to be examined E and enters the aqueous humor, and the aqueous humor can be heated by the near-infrared light. The light source 1 is an example of the "heating means" in the present invention, and is not limited thereto as long as it can apply heat to the liquid. For example, a laser light source, an LED light source, or the like may be used. Further, instead of the light source 1, a poultice device, a hot towel, or the like may be adopted as the "heating means".

[0026] The position where the near-infrared light is irradiated from the light source 1 to the eye to be examined E is grasped as the heating position of the eye to be examined E. However, in order to facilitate the grasping, the light source 1 may irradiate the eye to be examined E with light from a plurality of light sources at different angles, and the portion where the plurality of lights intersect may be grasped as the heating position.

[0027] The thermographic camera 2 is a device that analyzes the infrared rays radiated from the aqueous humor of the eye to be examined E to which heat has been applied and photographs the temperature distribution of a predetermined region as an image, and a known infrared thermographic camera can be used. The thermographic camera 2 is connected to the estimation device 3 and is configured to be able to transmit the acquired temperature distribution information of the aqueous humor (the data of the photographed temperature distribution image) to the estimation device 3. Note that the thermographic camera 2 is an example of the "temperature distribution acquisition means" in the present invention.

[0028] The thermographic camera 2 captures the eye under examination E from the time when the light source 1 starts irradiating near-infrared light on the eye under examination E, and acquires temperature distribution information of the eye under examination E (aqueous humor). The thermographic camera 2 acquires, for example, the temperature distribution information of the eye under examination E at a shooting interval of 1 frame per second for 20 seconds from the time when the light source 1 starts irradiation. The acquired temperature distribution information of the eye under examination E is transmitted from the thermographic camera 2 to the estimation device 3 as a temperature distribution image of the eye under examination E. The temperature distribution image transmitted from the thermographic camera 2 to the estimation device 3 can be displayed on the display unit 36 of the estimation device 3 described later.

[0029] The estimation device 3 is configured to acquire the temperature distribution information transmitted from the thermographic camera 2 and estimate the flow state of the aqueous humor based on the acquired temperature distribution information, and can visualize the estimated flow state of the aqueous humor. The estimation device 3 is an example of the "estimation means" in the present invention, and for example, a general-purpose personal computer can be used.

[0030] As shown in FIG. 2, the estimation device 3 includes a CPU 31, a ROM 32, a RAM 33, a storage device 34, a display processing unit 35, a display unit 36, an input unit 37, and a communication interface unit 38, and a bus 30 for transmitting control signals or data signals between the units is provided.

[0031] When the power is turned on to the estimation device 3, the CPU 31 loads various programs stored in the ROM 32 or the storage device 34 into the RAM 33 and executes them. In the present embodiment, the CPU 31 reads and executes the programs stored in the ROM 32 or the storage device 34, thereby realizing the functions of an image generation means 41, a region setting means 42, a temperature calculation means 43, a direction estimation means 44, and a speed estimation means 45 (shown in FIG. 3) described later.

[0032] The storage device 34 may be a non-volatile storage device such as a flash memory, an SSD, a magnetic storage device (e.g., HDD, etc.), an optical disk, etc., or may be a volatile storage device such as a RAM, and stores programs executed by the CPU 31 and data referred to by the CPU 31. Further, a conversion table 50 described later is stored in the storage device 34.

[0033] The display processing unit 35 displays the display data given from the CPU 31 on the display unit 36. As the display unit 36, for example, a liquid crystal display can be used.

[0034] The input unit 37 includes a group of buttons for receiving the operation input of the user, and includes an interface circuit for recognizing the press (operation) input of each button and outputting it to the CPU 31, but a touch panel input method may be adopted as the input unit 37.

[0035] The thermographic camera 2 is connected to the communication interface unit 38, and the estimation device 3 is configured to be able to acquire the temperature distribution image transmitted from the thermographic camera 2. Further, the light source 1 may be connected to the communication interface unit 38, and the estimation device 3 may be configured to control the irradiation of near-infrared light from the light source 1 to the eye to be examined E (turning on and off of the light source 1), or other terminal devices etc. may be connected to the communication interface unit 38, and the estimation device 3 may be configured to be able to transmit the estimation result of the aqueous humor flow state to the terminal device etc.

[0036] Regarding the functions realized by the estimation device 3 configured as described above, it will be described with reference to FIG. 3. FIG. 3 is a functional block diagram for explaining the functions that play a major role in the estimation device 3 of the present embodiment, and is composed of an image generation means 41, a region setting means 42, a temperature calculation means 43, a direction estimation means 44, and a speed estimation means 45. Not all of these means are essential components of the estimation device 3, and the functions of the estimation device 3 can be appropriately changed in consideration of the type of liquid to be heated, the surrounding environment, weather conditions, the use of the system 100, the calculation load of the estimation device 3, etc.

[0037] The image generation means 41 generates a processing target image D to be used for estimating the flow state of the aqueous humor from the plurality of temperature distribution images D acquired by the estimation device 3. P This function is realized as follows, for example. As a premise, the thermographic camera 2 has acquired the temperature distribution information of the eye to be examined E at a shooting interval of 1 frame per second for 20 seconds from the time when the light source 1 starts irradiation, and the estimation device 3 has acquired a total of 20 temperature distribution images D n (n = 1 to 20).

[0038] First, the CPU 31 of the estimation device 3 selects one temperature distribution image as a reference from the temperature distribution images D n (n = 1 to 20) of the eye to be examined E acquired from the thermographic camera 2 via the communication interface unit 38. For example, the temperature distribution image D5 taken 5 seconds after the start of the near-infrared light irradiation is selected as the reference image D s . Note that the acquisition time of the reference image D s is not limited to 5 seconds after the start of heating, but can be changed according to the type of the liquid to be heated, the heating method, the use of the system 100, etc., and may be determined by experiments, for example. Also, a plurality of temperature distribution images are selected from the acquired temperature distribution images D n (n = 1 to 20) of the eye to be examined E, and the average image of these plurality of temperature distribution images may be used as the reference image D s .

[0039] Subsequently, the CPU 31 selects one temperature distribution image from the temperature distribution images D s taken after the reference image D n is taken. For example, the temperature distribution image D6 taken 6 seconds after the start of the near-infrared light irradiation is selected, and the reference image D s is subtracted from the temperature distribution image D6 to generate a differential image of the temperature distribution, which is used as the processing target image D P . The generated processing target image D P is not limited to one, and there may be a plurality of processing target images D Pmay be generated. For example, a temperature distribution image D6 taken 6 seconds after the start of near-infrared light irradiation and a temperature distribution image D7 taken 7 seconds after the start of near-infrared light irradiation are selected, and a reference image D s is subtracted from each of the temperature distribution image D6 and the temperature distribution image D7 to generate two processing target images D P .

[0040] The processing target image D P does not necessarily have to be a difference image generated from the reference image D s and the temperature distribution image D n . Depending on the type of liquid to be heated, the heating method, the use of the system 100, etc., the temperature distribution image D n may be directly used as the processing target image D P to estimate the flow state of the liquid. However, when estimating the flow state of a liquid such as aqueous humor, which has a very slow flow and the speed at which the applied heat diffuses in the liquid is faster than the speed of the flow of the liquid itself, using the difference image generated from the reference image D s and the temperature distribution image D n as the processing target image D P has the advantage that the flow state can be easily visualized.

[0041] The region setting means 42 has a function of dividing the processing target image D P into a plurality of unit regions, and this function is realized, for example, as follows. When the CPU 31 of the estimation device 3 acquires the processing target image D P of the eye to be examined E generated by the image generation means 41 as shown in FIG. 4, as shown in FIG. 5, an analysis region A is set for the processing target image D P .

[0042] The analysis region A is, for example, such that the center position of the region coincides with the heating position by the light source 1 (the position on the eye to be examined E heated by the light source 1), for the processing target image D Pis set for. In the present embodiment, as shown in FIG. 5, the analysis region A is configured by arranging hexagonal unit regions in a honeycomb pattern so that the outer shape of the entire region is substantially hexagonal. By setting such an analysis region A for the processing target image D P the processing target image D P can be divided into a plurality of unit regions.

[0043] The temperature calculation means 43 has a function of calculating the temperature of each unit region, and this function is realized as follows, for example. The CPU 31 of the estimation device 3 acquires the temperature of one unit region to be calculated for temperature based on the processing target image D P and also acquires the temperatures of other unit regions adjacent to the one unit region based on the processing target image D P . Subsequently, the average value of those temperatures is calculated, and the calculated average value is set as the temperature of one unit region. By calculating the temperature of one unit region in consideration of the temperatures of the surrounding unit regions in this way, it is possible to suppress the temperature variation more than using the temperature of the one unit region as it is, so that the temperature of each unit region can be calculated accurately. Note that, in order to calculate the temperature of one unit region, it is not necessarily required to use the temperatures of all adjacent unit regions, and the temperature calculation method can be appropriately changed in consideration of the type of the liquid to be heated, the surrounding environment, the weather conditions, the use of the system 100, the calculation load of the estimation device 3, and the like.

[0044] For example, when the unit region H1 shown in FIG. 5 is set as the target region for temperature calculation, the CPU 31 acquires the temperature T1 of the unit region H1 from the data of the processing target image D P and also acquires the temperatures T2, T3, T4, and T5 of the four unit regions H2, H3, H4, and H5 adjacent to the unit region H1 from the data of the processing target image D P . The temperature T A1 calculated by averaging all five obtained temperatures (T1, T2, T3, T4, T5) is set as the temperature of the unit region H1. The CPU 31 can calculate the temperatures of all the unit regions constituting the analysis region A set in the processing target image D P in the same manner.

[0045] The direction estimation means 44 has a function of estimating the direction of the aqueous humor flow from the processing target image D P and this function is realized as follows, for example. First, the CPU 31 of the estimation device 3 sets two positions that are opposite to each other within the analysis region A of the processing target image D P and calculates the temperature difference between these two positions. For example, as shown in FIG. 6(a), from among the unit regions located in the outer peripheral portion of the analysis region A, two unit regions H A1 and H A2 that are opposite to each other are set, and the difference between the temperature of the unit region H A1 and the temperature of the unit region H A2 is calculated. Note that, for the sake of easy understanding, the temperature distribution is not depicted in the processing target image D P of FIG. 6.

[0046] Similarly, as shown in FIG. 6(b), five pairs of two unit regions that are opposite to each other are set, and for each pair, the temperature difference between the two unit regions (the unit regions H B1 and H B2 , H C1 and H C2 , H D1 and H D2 , H E1 and H E2 , H F1 and H F2 constituting the pair in FIG. 6(b)) is calculated. From among the six pairs of unit regions thus obtained, one pair in which the temperature difference between the two unit regions is the largest is selected. Here, it is assumed that the temperature difference between the unit regions H B1 and H B2 is the largest, and one pair composed of these two unit regions is selected.

[0047] Subsequently, the CPU 31 estimates the direction from the unit region on the lower temperature side to the unit region on the higher temperature side among the two unit regions H B1 and H B2 constituting the selected one pair as the direction in which the aqueous humor flows. For example, if the temperature of the unit region H B1 is lower than the temperature of the unit region H B2When it is lower than the temperature of B1 from the unit area H B2 it is estimated that the aqueous humor flows in the direction toward the unit area H

[0048] In the present embodiment, two positions in each pair are set on the outer peripheral portion of the analysis region A and face each other (on the diagonal line), but the present invention is not limited to this. For example, as shown in FIG. 6(d), one of the two positions forming a pair is set at the center of the analysis region A and the other is set at the outer peripheral portion of the analysis region A, and the direction of the flow of the aqueous humor may be estimated based on the temperature difference between the center position of the analysis region A and the positions of a plurality of outer peripheral portions. In this example, six pairs each composed of the unit area H0 at the center of the analysis region A and the unit area H 01 、H 02 、H 03 、H 04 、H 05 、H 06 、at the outer peripheral portion are set, and the difference between the temperature of the unit area H0 and the temperature of the unit area H 01 and the difference between the temperature of the unit area H0 and the temperature of the unit area H 02 are calculated, and the temperature difference between the two unit areas of each pair is calculated in this way.

[0049] Note that the two positions to be paired may not be each one unit area, but may be an aggregate of unit areas formed from a plurality of unit areas. In that case, the temperature of the aggregate of the unit areas may be the average value of the temperatures of the unit areas forming the aggregate.

[0050] Also, when the image generation means 41 generates a plurality of processing target images D P the temperature of each unit area obtained from those plurality of processing target images D P processing target image D of the temperature of each unit area obtained from the plurality of processing target images D PThe average value between them may be used as the temperature of each unit region, and the flow direction may be estimated as described above based on the average temperature. Alternatively, for each of the plurality of processing target images D P the flow direction may be estimated as described above, and the direction in which the aqueous humor flows may be estimated by comprehensively considering the obtained results.

[0051] The velocity estimation means 45 has a function of estimating the flow velocity of the aqueous humor from the temperature difference between two positions used by the direction estimation means 44 to estimate the flow direction of the aqueous humor, and this function is realized, for example, as follows.

[0052] The CPU 31 of the estimation device 3 collates the temperature difference between two positions, that is, the unit regions H B1 and H B2 used by the direction estimation means 44 to estimate the flow direction of the aqueous humor, with the conversion table 50 stored in the storage device 34, and estimates the flow velocity derived from the temperature difference as the flow velocity of the aqueous humor. Specifically, the conversion table 50 is created in advance by quantifying the relationship between the change amount of the temperature difference between two positions and the flow velocity using a model that measures the temperature difference between two positions at various flow velocities, and the relationship between the time change amount (slope) of the temperature difference and the flow velocity is defined. By comparing the change amount of the temperature difference between two positions actually acquired by the estimation device 3 with this conversion table 50, the flow velocity of the aqueous humor can be estimated. The estimated flow velocity of the aqueous humor is transmitted from the CPU 31 to the display processing unit 35 as display data, and can be displayed near the captured image and the direction indication image of the eye to be examined E displayed on the display unit 36.

[0053] An example of the conversion table 50 is shown in Table 1. In the conversion table 50 of Table 1, the relationship between the change amount of the temperature difference between two positions and the flow velocity is quantified using a model that measures the temperature difference between two positions at flow velocities of 0 μL / min (no flow), 5 μL / min, 10 μL / min, 15 μL / min, and 20 μL / min, and such a conversion table 50 is created in advance and stored in the storage device 34. Note that regression analysis may be performed in advance based on the relationship between the change amount of the temperature difference and the flow velocity, and the obtained regression equation may be used as the conversion table 50.

[0054]

Table 1

[0055] The CPU 31 obtains the amount of change in the temperature difference based on the temperature difference between two positions used by the direction estimation means 44 to estimate the direction in which the aqueous humor flows, and estimates the flow rate corresponding to the amount of change in the temperature difference in the conversion table 50 as the flow rate of the aqueous humor. For example, when the amount of change in the temperature difference based on the temperature difference between two positions used by the direction estimation means 44 to estimate the direction in which the aqueous humor flows is calculated to be 0.0158, since the closest value in the conversion table 50 is 0.016, the CPU 31 estimates the flow rate of the aqueous humor to be 15 μL / min.

[0056] In the present embodiment, the estimation device 3 estimates the direction in which the aqueous humor flows and the flow rate of the aqueous humor from the temperature difference between two positions in the analysis region A by the direction estimation means 44 and the speed estimation means 45, but estimation may be performed using the temperature ratio instead of the temperature difference.

[0057] The main processing flow of the liquid flow state estimation method for estimating the flow state of the aqueous humor of the eye to be examined E, which is performed by the liquid flow state estimation system 100 configured as described above, will be described with reference to the flowchart shown in FIG. 7.

[0058] First, the light source 1 is turned on, and near-infrared light irradiation of the eye to be examined E is started (step S101). As a result, the near-infrared light passes through the cornea of the eye to be examined E and enters the aqueous humor, and heating of the aqueous humor by the near-infrared light is started.

[0059] While continuously irradiating the eye to be examined E with near-infrared light from the light source 1, the eye to be examined E is photographed with the thermographic camera 2, and temperature distribution information of the eye to be examined E (aqueous humor) is acquired (step S102). In the present embodiment, the thermographic camera 2 acquires the temperature distribution information of the eye to be examined E at an imaging interval of 1 frame per second for 20 seconds from the time when the light source 1 starts irradiation, and the temperature distribution information acquired by the thermographic camera 2 is the temperature distribution image D of the eye to be examined En It is transmitted from the thermographic camera 2 to the estimation device 3 with (n = 1 to 20). The estimation device 3 acquires temperature distribution images of a total of 20 eyes to be examined E, and stores all or some of the temperature distribution images in the storage device 34 as needed.

[0060] The estimation device 3 is the temperature distribution image D of the eye to be examined E n When acquiring (n = 1 to 20) from the thermographic camera 2, the temperature distribution image D n Among (n = 1 to 20), the temperature distribution image D5 taken 5 seconds after the start of near-infrared light irradiation is selected as the reference image D s (Step S103). The estimation device 3 is the reference image D s One temperature distribution image D other than the one used as n (n = 1 to 20) is selected, and a temperature distribution difference image is generated by subtracting the reference image D n from the selected temperature distribution image D n , and this is set as the image D to be processed s (Step S104). P

[0061] On the other hand, the estimation device 3 sets an analysis area A divided into a plurality of unit areas for the image D to be processed P (Step S105). Subsequently, the estimation device 3 acquires the temperatures of all the unit areas constituting the analysis area A based on the image D to be processed P . The temperature of one unit area in one image D to be processed P is calculated as the average value of the temperature of the unit area obtained from one image D to be processed P and the temperatures of a plurality of adjacent unit areas.

[0062] Subsequently, the estimation device 3 is the image D to be processed P ​Set a plurality of pairs of two positions within the analysis region A, and calculate the temperature difference between the two positions constituting each pair (step S107). Next, the estimation device 3 selects one pair from the plurality of pairs in which the temperature difference between the two positions constituting each pair is the largest (step S108), and among the two positions constituting the selected one pair, the direction from the position on the lower temperature side to the position on the higher temperature side is estimated as the direction in which the aqueous humor flows (step S109).

[0063] In addition, the estimation device 3 collates the temperature difference between the two positions used for estimating the flow direction of the aqueous humor with the conversion table 50 stored in the storage device 34, and estimates it as the flow velocity of the aqueous humor derived from the temperature difference (step S110).

[0064] In this way, the liquid flow state estimation system 100 according to the present embodiment and the liquid flow state estimation method implemented using the system 100 take advantage of the characteristic that heat can be non-invasively applied to the liquid, and by grasping the temperature distribution of the liquid to which heat has been applied, the flow state of the aqueous humor, that is, the flow direction and flow velocity of the aqueous humor, can be estimated non-invasively.

[0065] In the above-described embodiment, the temperature distribution of the aqueous humor during the heating period in which heat is applied to the aqueous humor by the irradiation of near-infrared light by the light source 1 is acquired, and the flow state of the aqueous humor is estimated based on the temperature distribution during the heating period. However, after applying heat to the aqueous humor, the irradiation of near-infrared light by the light source 1 is stopped, the temperature distribution of the aqueous humor during the cooling period after the application of heat to the aqueous humor is stopped is acquired, and the flow state of the aqueous humor may be estimated based on the temperature distribution during the cooling period, or the temperature distributions during both the heating period and the cooling period may be acquired, and the flow state of the aqueous humor may be estimated based on both of them.

[0066] Here, in the liquid flow state estimation system 100 according to the present embodiment and the liquid flow state estimation method implemented using the system 100, it is possible to estimate the flow state of the liquid, such as the presence or absence of liquid flow and the direction of the flow, even from the acquired temperature distribution information of one liquid (one temperature distribution image). On the other hand, when estimating the flow state of the liquid by comprehensively estimating the flow states of the liquid estimated based on a plurality of temperature distribution information (a plurality of temperature distribution images with different acquisition timings), the estimation accuracy can be improved compared to the case of estimating the flow state of the liquid from one temperature distribution information.

[0067] As described above, the liquid flow state estimation method and the liquid flow state estimation system according to the present invention have been described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, an analysis region in which a plurality of regular hexagonal unit regions are arranged in a honeycomb shape is set for the temperature distribution image. However, the present invention is not limited thereto as long as the direction of the liquid flow can be accurately estimated in the analysis region. For example, as shown in FIG. 8(a), an analysis region A1 composed of a plurality of square unit regions may be set, or as shown in FIG. 8(b), a circular analysis region A2 obtained by dividing a plurality of concentric circles into unit regions such that the sizes of the unit regions are equal may be set. Further, the analysis region may be set with each pixel as a unit region.

[0068] Also, in the above-described embodiment, the thermographic camera 2 acquires the temperature distribution image of the eye to be examined E at an imaging interval of 1 frame per second. However, the present invention is not limited thereto, and for example, the temperature distribution image may be acquired at an imaging interval of 10 frames per second, and the average image of a plurality of consecutive frames (for example, 3 frames) may be used as the temperature distribution image processed by the estimation device 3 to estimate the flow state of the aqueous humor. By using the average image of the temperature distribution images of several frames before and after in this way, the variation in the images for each imaging and the variation in the temperature over time can be reduced.

[0069] Furthermore, although the method for estimating the flow state of a liquid and the system for estimating the flow state of a liquid according to the present invention are used to estimate the flow state of aqueous humor in the above-described embodiment, the applicable fields are not limited thereto. For example, it is also applicable to grasping the state of the flow of water or oil in order to detect the presence or absence of water leakage or oil leakage and the location of its cause, grasping the state of the flow of blood in the human body, verifying the processing accuracy of microchannels, and the like.

Example

[0070] The method for estimating the flow state of a liquid and the system for estimating the flow state of a liquid according to the present invention will be described more specifically with reference to the following examples, but the scope of the present invention is not limited to these examples and the like.

[0071] [Evaluation device] An experiment for estimating the flow state of a liquid (water) was conducted using an evaluation device 5 as shown in FIG. 9. The evaluation device 5 has a resin gasket 52 with a liquid flow space 521 having a circular shape in plan view formed on a glass substrate 51, and a cover glass 53 is disposed on the gasket 52 to form an integral unit. An inflow portion 522 into which an inflow pipe 54 for supplying liquid to the gasket 52 is inserted is provided on one side portion (the left side in FIG. 9) of the liquid flow space 521 of the gasket 52, and an outflow portion 523 into which an outflow pipe 55 through which the liquid is discharged from the gasket 52 is inserted is provided on the opposite side portion (the right side in FIG. 9) of the liquid flow space 521. Further, the evaluation device 5 is configured to be able to generate a flow in the liquid in the liquid flow space 521 of the gasket 52 by supplying liquid from the inflow portion 522 of the gasket 52 and discharging the liquid from the outflow portion 523 using a pump (not shown, MINI-PUMP VARIABLE FLOW manufactured by Fisher Scientific), and the flow rate of the liquid in the liquid flow space 521 can be controlled to a desired speed by controlling the pump.

[0072] The evaluation device 5 irradiates near-infrared light from a near-infrared light source (not shown, an illumination device for an infrared halogen lamp made by Sumitomo Optical Glass) toward the center of the liquid flow space 521 of the gasket 52, and can capture a temperature distribution image of the liquid in the liquid flow space 521 by a thermographic camera (not shown, Boson320 made by FLIR Systems, 92° (HFOV) 2.3 mm).

[0073] [Example 1] Using such an evaluation device 5, an experiment was conducted to estimate the flow state of water as the liquid to be estimated. First, water was flowed into the liquid flow space 521 at a flow rate of 20 μL / min, and heating of the water was started by irradiating near-infrared light with a luminous intensity of 24.6 mW. Temperature distribution images of the water in the liquid flow space 521 at the start of irradiation (0 seconds), 5 seconds after the start of irradiation, 15 seconds after, and 30 seconds after were captured with a thermographic camera. Fig. 10 shows a schematic representation of the four captured temperature distribution images. Fig. 10 shows how the temperature distribution of the continuously heated water changes with time while the flow rate of the water is fixed.

[0074] [Example 2] Next, using such an evaluation device 5, heating of the water was started by irradiating near-infrared light in four patterns in which the flow rate of the water flowing into the liquid flow space 521 was changed to 0 μL / min (no flow), 5 μL / min, 10 μL / min, and 20 μL / min, and a temperature distribution image of the water in the liquid flow space 521 15 seconds after the start of irradiation was captured with a thermographic camera. Fig. 11 shows a schematic representation of the four captured temperature distribution images. Fig. 11 shows how the temperature distribution differs depending on the difference in the flow rate of the water when a predetermined time has elapsed since the start of heating.

[0075] It can be seen from the temperature distribution images captured in Example 1 and Example 2 that by applying heat to the liquid and obtaining the temperature distribution of the liquid to which heat has been applied, the flow state of the liquid can be estimated based on the obtained temperature distribution.

[0076] [Quantification of water fluidity] From the temperature distribution images obtained in the patterns of each flow rate in Example 2, an attempt was made to quantify the fluidity of water. First, for the temperature distribution image taken at an imaging interval of 5 seconds in the pattern of a flow rate of 0 μL / min (no flow) and the temperature distribution image taken at an imaging interval of 5 seconds in the pattern of a flow rate of 20 μL / min, two regions a and region b as shown in FIG. 12 were set, and using the method of the above-described embodiment, the temperature of each region was obtained, and the temperature difference between region a and region b was calculated. When the temperature differences between region a and region b after the start of heating of water (0 seconds), 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, and 30 seconds from the start of heating were plotted on a graph with the temperature difference on the vertical axis and the elapsed time on the horizontal axis, it could be illustrated as shown in FIG. 13. Looking at FIG. 13, it is understood that the pattern of a flow rate of 0 μL / min (no flow) continues to have no temperature difference between region a and region b, and the plots of the pattern of a flow rate of 20 μL / min are arranged on a substantially rising straight line.

[0077] In addition to the four flow rate patterns of Example 2, the same experiment was also conducted for a pattern in which the flow rate of water flowing in the liquid flow space 521 was set to 15 μL / min. A graph similar to FIG. 13 was created for a total of five flow rate patterns, and the slope (Δy / Δx) of the temperature difference for each flow rate pattern was calculated. When the calculated slope (Δy / Δx) of the temperature difference for each flow rate pattern was plotted as the change amount of the temperature difference for each flow rate pattern on a graph with the change amount of the temperature difference on the vertical axis and the flow rate on the horizontal axis, it could be illustrated as shown in FIG. 14. Looking at FIG. 14, it is understood that the change amount of the temperature difference is determined in proportion to the flow rate, and it can be seen that by conducting such an experiment, the conversion table 50 in the above-described embodiment can be created in advance.

Description of Reference Numerals

[0078] 100 Liquid Flow State Estimation System 1 Light Source (Heating Means) 2 Thermographic Camera (Temperature Distribution Acquisition Means) 3 Estimation Device (Estimation Means) 41 Image Generation Means 42 Region Setting Means 43 Temperature Calculation Means 44 Direction estimation means 45 Speed estimation means E Eye to be examined 5 Evaluation device

Claims

1. Step (a) of applying heat to a liquid; Step (b) of obtaining the temperature distribution of the liquid to which heat has been applied; Step (c) of estimating the flow state of the liquid based on the obtained temperature distribution, and having, In step (a), heat is applied to the liquid by irradiating the liquid with light from a light source, In step (b), a plurality of temperature distributions of the liquid at different times are obtained, In step (c), the flow state of the liquid is estimated based on the plurality of obtained temperature distributions. A method for estimating the flow state of a liquid.

2. Said step (c) is Step (c1) of setting two positions that are opposite to each other within the region where the temperature distribution is obtained, and obtaining the temperature difference or temperature ratio between the two positions; Step (c2) of executing step (c1) a plurality of times, and selecting one pair having the maximum temperature difference or temperature ratio from among the plurality of pairs of the two positions within the region where the temperature distribution is obtained; Step (c3) of estimating the direction in which the liquid flows as the direction from the position on the lower temperature side to the position on the higher temperature side among the two positions constituting the selected one pair. The method for estimating the flow state of a liquid according to claim 1.

3. Said step (c) is The method for estimating the flow state of a liquid according to claim 2, further including step (c4) of estimating the flow velocity of the liquid from the temperature difference or temperature ratio between the two positions constituting the one pair selected in step (c2).

4. In step (c), the region where the temperature distribution is obtained is divided into a plurality of unit regions, and the flow state of the liquid is estimated based on the temperatures of the plurality of unit regions. The method for estimating the flow state of a liquid according to any one of claims 1 to 3.

5. The temperature of one of the unit regions is calculated as the average value of the temperature of the one unit region determined by the temperature distribution and the temperature of another unit region adjacent to the one unit region. The method for estimating the flow state of a liquid according to claim 4.

6. In step (b), at least one of the temperature distribution of the liquid during the heating period when heat is being applied to the liquid and the temperature distribution of the liquid during the cooling period after the application of heat to the liquid has been stopped is obtained, The method for estimating the flow state of a liquid according to any one of claims 1 to 5, wherein in the step (c), the flow state of the liquid is estimated based on at least one of the temperature distribution during the heating period and the temperature distribution during the cooling period.

7. The method for estimating the flow state of a liquid according to any one of claims 1 to 6, wherein in the step (b), the temperature distribution of the liquid is obtained by photographing the liquid with a thermographic camera.

8. Heating means for applying heat to the liquid, Temperature distribution acquisition means for acquiring the temperature distribution of the liquid to which heat has been applied, Estimation means for estimating the flow state of the liquid based on the acquired temperature distribution, and the heating means is a light source that applies heat to the liquid by irradiating the liquid with light, the temperature distribution acquisition means acquires a plurality of temperature distributions of the liquid at different times, the estimation means estimates the flow state of the liquid based on the plurality of acquired temperature distributions, a liquid flow state estimation system.

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