Temperature measurement method, thermophysical property value calculation method, and object interior search method

Abstract

Provided are a temperature measurement method, a thermophysical property value calculation method, and an object interior search method that make it possible to determine a thermophysical property value of a substance under measurement for each timing by using time series measurement data of the substance under measurement and a parameter value for each timing. A temperature measurement method according to the present invention, in which a substance under measurement having an unknown thermophysical property value is heated under a constant heating condition and the temperature of the heated surface is measured, comprises: a step for recording temperature responses of at least two standard substances being heated in time series, the standard substances having known thermophysical properties; a step for determining, for each timing, a parameter value derived from at least two temperature measurement devices 10, the parameter value being used to calculate the thermophysical property value of the substance under measurement on the basis of the recorded time series data; a step for then measuring the temperature response of the substance under measurement in time series as the temperature is changed; and a step for determining the thermophysical property value of the substance under measurement for each timing by using the time series measurement data of the substance under measurement and the parameter value for each timing.

Description

Temperature measurement method, thermophysical property value calculation method, and object interior exploration method

[0001] The present invention relates to a temperature measurement method, a thermophysical property calculation method, and an object interior exploration method.

[0002] In the industrial and medical fields, it is desirable to explore the internal state of an object nondestructively and noninvasively.

[0003] For example, in the medical field, skin malignancies (skin cancer) have traditionally been diagnosed by visual examination using a dermoscope, which requires skill. Furthermore, because a dermoscope can only obtain information on the surface of the skin, it cannot measure the progression of cancer inside the skin.

[0004] Ultrasound is a well-known method for examining the inside of living organisms. Ultrasound examinations examine the structure of a subject's internal tissues by measuring the tissue's acoustic impedance. However, in the case of skin cancer, the acoustic impedance is almost the same as that of healthy tissue, and the condition of the skin also affects the acoustic impedance, resulting in problems with resolution and accuracy. Therefore, there is a need for a method to quickly detect skin cancer with high accuracy and precision.

[0005] Additionally, in the industrial field, X-ray equipment is sometimes used to inspect for defects inside metals. However, there are concerns that X-ray irradiation may damage the sample. The equipment is often large-scale, and because it uses high-energy X-rays that are harmful to the human body, the environments in which it can be used are limited. For this reason, it is desirable to be able to detect defects inside metals using simpler non-destructive testing for the manufacturing and maintenance of industrial products. Furthermore, detecting impurities contained in food is also important, and non-destructive, non-invasive testing is preferable.

[0006] Under these circumstances, the present inventors have proposed a method for detecting skin cancer, etc., by generating a heat pulse in a high-precision temperature measurement device and measuring the degree of skin cancer invasion. This device applies a heat pulse to the skin, accurately measures the temperature decay after the heat pulse is stopped, and calculates the equivalent thermal conductivity k. The equivalent thermal conductivity k can be calculated using the following equation (1).

[0007]

[0008] Here, ΔT(t) is the temperature difference from the steady state temperature due to the application of a heat pulse, and P(t) is the power (W) when the heat pulse is applied. Both change with time t, so they are expressed as a function of time t. ｈ is the heating time of the heat pulse. １ , a ２ is a device-specific constant (device constant) that can be calculated from the temperature decay of two different materials with known thermal conductivities k.

[0009] This method can be used to detect skin cancer by calculating the difference in equivalent thermal conductivity between healthy and cancerous areas of the skin.

[0010] JP 4-224737 JP 2023-36095 JP 2003-75371 JP 2024-11249 JP 2016-217885 Patent No. 7157103 Patent No. 7282238 Nachiket M Kharalkar, Linda J Hayes and Jonathan W Valvano, “ Pulse-power integrated-decay technique for the measurement of thermal conductivity”, Meas, Sci. Technol., 2008, 19, 075104

[0011] A detailed explanation will be given of the conventional method for calculating equivalent thermal conductivity by applying a heat pulse. Figure 1 shows the temperature rise when a heat pulse is applied to silicone rubber and gelled water (water that has been gelled with agar or other materials to stop it from flowing) as standard materials, and the temperature decay data after the application of the heat pulse is stopped. In the case of this device, the heating time and heating power P(t) are controlled to be constant. For the two standard materials listed on the left, whose thermal conductivity k is known, the integral value of the temperature decay in Figure 1 can be calculated using the following equation (2), and from equation (1), a １ , a ２ can be calculated.

[0012]

[0013] In this way, the equipment constant a １ , a ２ Once is determined, a similar temperature pulse is applied to the material to be measured, and the integral value of the temperature of the material to be measured, calculated using equation (2), is obtained from the surface temperature data. １ , a ２ Since the thermal conductivity k of the substance being measured is known, it is possible to measure the equivalent thermal conductivity k of the substance being measured using equation (1). In the example of Figure 2, the temperature decay curves of skin cancer and healthy areas are different. As a result, the equivalent thermal conductivity k calculated using equation (1) is also different, making it possible to determine whether the skin is cancerous or healthy.

[0014] However, this method cannot identify the depth location of skin cancer, which distinguishes it from healthy areas. In other words, conventional measurement methods have the problem of being unable to clarify the extent to which changes in thermophysical properties due to cancer infiltration have occurred. Furthermore, conventional measurement methods have the drawback of being difficult to detect abnormalities in the equivalent thermal conductivity k near the skin surface. In particular, in early-stage skin cancer, cancerous tissue often remains within the epidermis, making it difficult to measure its equivalent thermal conductivity.

[0015] A temperature measurement method and a thermophysical property calculation method according to an embodiment of the present invention are a temperature measurement method and a thermophysical property calculation method for heating a substance to be measured whose thermophysical properties are unknown under constant heating conditions and measuring the temperature of the heating surface, and are characterized by comprising the steps of: recording the temperature response of at least two standard substances with known thermophysical properties when heated in time series; determining parameter values ​​derived from at least two temperature measurement devices for each time period for calculating the thermophysical properties of the substance to be measured using the time-series recorded data; subsequently measuring the temperature response of the substance to be measured as the temperature changes in time series; and determining the thermophysical property values ​​of the substance to be measured for each time period by using the time-series measurement data of the substance to be measured and the parameter values ​​for each time period.

[0016] In particular, the equivalent thermal conductivity or equivalent thermal diffusivity can be calculated as the thermophysical property value of the substance to be measured.

[0017] In addition, the method for exploring the inside of an object according to an embodiment of the present invention is a method for exploring the inside of an object, which determines the presence or absence of an abnormality inside the measured material and its size by comparing the time changes of the thermophysical property values ​​of the measured material at multiple points, which are determined using the above-mentioned temperature measurement method and thermophysical property calculation method.

[0018] Furthermore, the difference in the time change of the thermophysical property value between the abnormal part and the normal part inside the measured substance or the difference in the time derivative of the time change is expressed by Equation (9). This is a method for investigating the inside of an object, which expresses the difference converted into length by the above method and identifies the position and size of an abnormal part in the material to be measured.

[0019] It should be noted that when referring to a temperature measurement method, a thermophysical property calculation method, and an object interior exploration method, the boundaries of the concepts may overlap. For example, a thermophysical property calculation method may be applied to an object interior exploration method.

[0020] According to an embodiment of the present invention, it is possible to provide a temperature measurement method, a thermophysical property calculation method, and an object interior exploration method that can determine the thermophysical property values ​​of a measured substance at each time by using time-series measurement data of the measured substance and parameter values ​​at each time.

[0021] 1 is a graph showing the change in temperature response ΔT(t) when a 3-second heat pulse is applied to the surface of silicone rubber and gelled water.

[0034] FIG. 1 is a graph showing the heat pulse response of cancerous skin and healthy areas measured using a temperature measurement device (thermal pulse radar).

[0035] FIG. 1 is a cross-sectional view showing the structure of a temperature measurement device.

[0036] FIG. 2 is a schematic diagram showing a skin model to be analyzed.

[0037] FIG. 3 is a table showing the thermal property values ​​of the skin model.

[0038] FIG. 4 is a schematic diagram showing a two-dimensional axisymmetric heat conduction numerical simulation model.

[0039] FIG. 5 is a table showing the thermal property values ​​of a simulation model assuming skin tissue.

[0040] FIG. 6 is a graph showing the temperature response of a measurement device surface when a medium (dermis) contains inclusions (fat layer);

[0041] FIG. 7 is a graph showing the time change when converted to equivalent thermal conductivity k(t);

[0042] FIG. 8 is a graph showing the difference between the equivalent thermal conductivity with inclusions (fat layer) and the equivalent thermal conductivity of the medium (dermis) alone;

[0043] FIG. 9 is a table showing the thermal property values ​​of a simulation model assuming metal and inorganic materials.

[0044] FIG. 10 is a graph showing the temperature response of a measurement device surface when a substrate material (carbon steel) contains various inclusions (aluminum). 1 is a graph showing the temperature response of the surface of a measuring device when various inclusions (soda glass) are included in a substrate material (carbon steel). This graph shows the time change when converted into equivalent thermal conductivity k(t). This graph shows the difference between the equivalent thermal conductivity with various inclusions and the equivalent thermal conductivity when the substrate material is only carbon steel. This graph shows the time change (second thermophysical property calculation method) of the equivalent thermal conductivity k(t) of carbon steel when brass, stainless steel (SUS), and tungsten are used as standard materials. This graph shows the time change of the equivalent thermal diffusivity α(t) of carbon steel when brass and stainless steel (SUS) are used as standard materials. This graph shows the time difference value change of the equivalent thermal conductivity k organized by the position of the inclusion and the characteristic length L, and the position of the inclusion (skin model). This graph shows the time difference value change of the equivalent thermal conductivity k organized by the position of the inclusion and the characteristic length L, and the position of the inclusion (metal / inorganic material model).

[0022] Hereinafter, a temperature measurement method, a thermophysical property calculation method, and an object interior exploration method according to embodiments of the present invention will be described with reference to Figures 1 to 21. Note that in each figure, the scale of each component may be changed as appropriate to make each component large enough to be recognized. Furthermore, the same or corresponding parts are given the same reference numerals, and duplicated explanations will be omitted.

[0023] First Embodiment: First Thermophysical Property Calculation Method The first thermophysical property calculation method will be described.

[0024] When there are two standard materials with known thermal conductivities as thermophysical properties (for example, Figure 1), the thermal conductivities k of standard materials 1 and 2 are １ , k ２ is the temperature response ΔT when a heat pulse is applied under constant conditions １ (t), ΔT ２ Using (t), it is expressed by equation (3). １ (t), a ２ (t) represents the device constant at each time as a function of time t.

[0025] From equation (3), the equipment constant a １ (t), a ２ (t) is calculated using equation (4).

[0026] Then, the temperature response ΔT(t) of the substance to be measured is measured under the same heating conditions as the standard substance, and the instrument constant a derived by equation (4) is calculated. １ (t), a ２ By using equation (5) from (t), it is possible to calculate the equivalent thermal conductivity k of the substance to be measured as a function of time k(t).

[0027] Since this equivalent thermal conductivity k(t) contains time information, it represents the equivalent thermal conductivity affected by the depth of the heat pulse. By looking at this value, the temperature measurement device can be used as a thermal pulse radar, like an electromagnetic wave radar, to estimate the location of areas with different thermal conductivity in the measured material.

[0028] Second Embodiment: Second Method for Calculating Thermophysical Properties A second method for calculating thermophysical properties will be described.

[0029] When there are three standard materials with known thermal conductivities as thermophysical property values, the equivalent thermal conductivity of the material to be measured can be calculated as a function of time k(t) using equation (6) as in the first thermophysical property calculation method.

[0030] The equipment constant a in equation (6) ０ (t), a １ (t), a ２ (t) is the thermal conductivity k of the three standard materials １ , k ２ , k ３ and temperature response ΔT １ (t), ΔT ２ (t), ΔT ３ (t), it can be calculated by solving the simultaneous equations of equation (7).

[0031] When the temperature response ΔT(t) of the substance to be measured at each time t is measured, the device constant a ０ (t), a １ (t), a ２ Using (t), the equivalent thermal conductivity k(t) of the measured substance at each time is calculated by equation (6).

[0032] Third Embodiment: Third Method for Calculating Thermophysical Properties A third method for calculating thermophysical properties will be described.

[0033] When there are N standard substances with known thermal conductivities as thermophysical properties, the equivalent thermal conductivity k(t) of the substance to be measured can be estimated by equation (8).

[0034] Here, the device constant a ｎ (t) is calculated as the solution of an N-th order simultaneous equation similar to equation (7).

[0035] Fourth Embodiment: Fourth Thermophysical Property Calculation Method A fourth thermophysical property calculation method will be described.

[0036] The thermal properties of the object are thermal conductivity k and specific heat c ｐ , and from the value of density ρ, α = k / (c ｐThe thermal diffusivity α is a quantity that indicates the speed at which the temperature distribution relaxes and reaches a thermal equilibrium state. Since the thermal diffusivity α is expressed as a function of the thermal conductivity k, the first to third thermophysical property calculation methods use the thermal diffusivity α instead of the thermal conductivity k of the standard material, and calculate the device constant a at each time t. ｎ (t) is derived, and α(t) of the substance to be measured can be calculated using equations (5), (6), and (8).

[0037] Next, an example of this embodiment will be described. (Example 1)

[0038] The following explanation will be given with reference to Figures 3 to 7. Figure 3 is a schematic longitudinal cross-sectional view of a temperature measurement device (thermal pulse radar), and Figure 4 shows a skin model that is the subject of numerical analysis. Figure 5 shows the thermal properties of the skin model in Figure 4, with the epidermis given three different thermal conductivities and a three-second heat pulse applied, as in Figure 1. Figure 6 shows the temperature response of a three-dimensional heat conduction model, and Figure 7 shows the time change in equivalent thermal conductivity at each time.

[0039] As shown in Figure 3, the temperature measurement device (thermal pulse radar) 10 comprises a thin-film thermosensitive element 1 for measurement, a thin-film thermosensitive element 2 for protective heating, a temperature control element 3, a pipe-shaped shaft 4 that houses these components, and a control processing unit (not shown) that controls each component. The tip of the shaft 4 is a temperature-sensing thermosensitive element 41 that functions as a probe. Furthermore, the thin-film thermosensitive element 1 for measurement and the thin-film thermosensitive element 2 for protective heating have basically the same specifications and characteristics.

[0040] The thin-film thermosensitive element 1 for measurement is a thin-film thermistor, and includes a thin-film element layer 12 on a substrate 11. The thin-film element layer 12 is a thermistor composition, and is made of an oxide semiconductor having a negative temperature coefficient. The thin-film element layer 12 is formed by a method such as sputtering.

[0041] The temperature control element 3 is disposed on the rear end side of the measurement thin-film thermosensitive element 1 and the protective heating thin-film thermosensitive element 2. A heat sink 31 and a thin-film thermosensitive element 32 for the temperature control element are provided on the front end side of the temperature control element 3, and a heat dissipation fin 33 is disposed on the rear end side. The thin-film thermosensitive element 32 for the temperature control element is disposed so as to be thermally coupled to the heat sink 31. The thin-film thermosensitive element 32 for the temperature control element functions to sense the temperature of the heat sink 31 and control the temperature of the Peltier element serving as the temperature control element 3.

[0042] Figure 4 shows a skin model to be numerically analyzed, showing the epidermis, dermis, fat, and muscle layers in the depth direction from the skin surface. Measurements are performed by contacting the temperature sensor 41 of the temperature measuring device 10 with the skin surface. Figure 5 shows the thermal property values ​​of the skin model.

[0043] FIG. 6 shows the results of a numerical simulation of the temperature response ΔT(t) of the temperature measuring device 10 when it is brought into contact with the skin model of FIG. 4 and heated for 3 seconds. First, the thermal conductivity k １ , k ２ The temperature response ΔT of known gel water and silicone rubber １ (t), ΔT ２ (t) to obtain the equipment constant a １ , a ２ Next, as shown in Figure 5, we performed a numerical simulation by changing the thermal conductivity of the skin in three ways.

[0044] FIG. 7 shows the change in equivalent thermal conductivity k(t) over time. k(t) was derived using the temperature response in FIG. 6 and the first thermophysical property calculation method. The temperature response in FIG. 6 does not clearly show the change in the thermal conductivity of the skin. However, when converted to equivalent thermal conductivity as shown in FIG. 7, the influence of thermal conduction in the skin appears at the peak time of 0.06 seconds, and this influence causes a difference in the equivalent thermal conductivity over time.

[0045] Furthermore, comparing the thermal conductivity values ​​shown in Figure 5 with Figure 7, the high thermal conductivity of the dermis is reflected for periods of less than one second, when the heat pulse has not yet reached the depths. As the heat propagates, the thermal conductivity decreases due to the influence of the fat layer, which has low thermal conductivity. When the heat pulse reaches the fat layer, which also has low thermal conductivity, the equivalent thermal conductivity decreases further, and when the heat pulse reaches the muscle layer, the equivalent thermal conductivity increases again. In this way, comparing the time change in thermal conductivity at multiple points reveals that it changes depending on the depth reached by the heat pulse.

[0046] Therefore, the temperature measurement method and the thermophysical property calculation method in each of the present embodiments and this Example 1 are thermophysical property calculation methods in which a substance to be measured whose thermophysical properties are unknown is heated under constant heating conditions and the temperature of the heating surface is measured. Since the integral value of the temperature decay in Figure 1 can be calculated from equation (2), the apparatus constants a1 and a2 can be calculated from equation (1), and (A) the method includes a step of recording the temperature response of at least two standard substances with known thermophysical properties during heating in chronological order.

[0047] From equation (3), the equipment constant a １ (t), a ２ (t) can be calculated using equation (4), and (B) includes a step of determining parameter values ​​derived from at least two temperature measuring devices at each time point in order to calculate the thermophysical property values ​​of the substance to be measured using time-series recorded data.

[0048] As shown in FIG. 6, there is also a subsequent step (C) of measuring the temperature response of the substance to be measured in time series when the temperature changes.

[0049] As shown in equation (5), (D) determining the thermophysical property values ​​of the measured substance at each time by using the time-series measurement data of the measured substance and the parameter values ​​at each time. In particular, the equivalent thermal conductivity or equivalent thermal diffusivity can be calculated as the thermophysical property value of the measured substance.

[0050] Example 2 As Example 2, a heat conduction simulation using a calculation model of skin will be described with reference to FIGS.

[0051] Fig. 8 shows a two-dimensional axisymmetric heat conduction numerical simulation model, Fig. 9 shows the thermal properties of a simulation model assuming skin tissue, Fig. 10 shows the temperature response of the measurement device surface when the medium (dermis) contains inclusions (fat layer), Fig. 11 shows the time change when converted into equivalent thermal conductivity k(t), and Fig. 12 shows the difference between the equivalent thermal conductivity with inclusions (fat layer) and the equivalent thermal conductivity of the medium (dermis) alone.

[0052] As shown in Figure 8, the simulation model used here is a heat conduction model in which the temperature measurement device 10 is a disk with a diameter of 2 mm, and a heat pulse is applied with a constant heat flux q from t = 0 seconds. The thermal properties of the medium are assumed to be constant, and inclusions with different thermal properties are placed inside it. Surfaces other than the heated surface are assumed to be adiabatic, and the medium is assumed to be the dermis, and the inclusion is assumed to be the fat layer.

[0053] The inclusion had a diameter of 6 mm and a thickness of 0.5 mm, and the distance d between the temperature measuring device 10 and the top end of the inclusion was set to 0.5 mm and 1 mm. Note that the heat flux q from the temperature measuring device 10 with a diameter of 2 mm was 2000 W / m ２ A heat pulse was applied.

[0054] The thermal properties of these materials are shown in Figure 9. Figure 10 shows the temperature response under the above conditions. The temperature response when d = 1 mm is almost the same as that of the medium (dermis), and cannot be distinguished in the figure.

[0055] Figure 11 shows the time variation of the equivalent thermal conductivity k(t) converted using the first thermophysical property calculation method. The equivalent thermal conductivity of the medium (dermis) gradually approaches 0.45 over time. The equivalent thermal conductivity is lowered due to the insertion of inclusions (fat layers) with low thermal conductivity. This effect is more pronounced the shorter the distance between the temperature measuring device 10 and the fat layer.

[0056] Figure 12 shows the difference value obtained by subtracting the equivalent thermal conductivity of the medium (dermis) alone from the equivalent thermal conductivity including the inclusion (fat layer). As in Figure 11, it shows that the difference becomes larger the closer the inclusion (fat layer) is to the temperature measuring device 10. It also becomes clear that the closer the inclusion (fat layer) is to the temperature measuring device 10, the earlier the difference begins to differ from the value of the medium (dermis) alone.

[0057] As described above, similar to the above-mentioned embodiments and Example 1, according to Example 2, the thermal property values ​​of the measured substance can be determined at each time by using the time-series measurement data of the measured substance and the parameter values ​​at each time.

[0058] Example 3 As Example 3, a heat conduction simulation using a calculation model of metal and inorganic materials will be described with reference to FIGS.

[0059] FIG. 13 shows the thermal property values ​​of a simulation model assuming metal and inorganic materials, and FIG. 14 shows the temperature response of a temperature measuring device when the substrate material (carbon steel) contains various inclusions (aluminum).

[0060] Fig. 15 shows the temperature response of the temperature measurement device when the substrate material (carbon steel) contains various inclusions (soda glass), Fig. 16 shows the time change when converted into equivalent thermal conductivity k(t), and Fig. 17 shows the difference between the equivalent thermal conductivity with various inclusions and the equivalent thermal conductivity for the substrate material (carbon steel) alone.

[0061] Using the simulation model shown in FIG. 8 of Example 2, a heat conduction simulation was carried out in which the substrate material was carbon steel (k = 43 W / mK). Aluminum (k = 237 W / mK) with a diameter of 6 mm and a thickness of 1 mm and soda glass (k = 1.03 W / mK) with a diameter of 6 mm and a thickness of 0.2 mm were set as inclusions, and the distance d between the temperature measuring device and the top end of the inclusion was assumed to be set to 1 mm and 2 mm. Note that the heat flux q from the temperature measuring device with a diameter of 2 mm was 20,000 W / m ２Figure 13 shows the thermal properties of the carbon steel substrate material, the aluminum inclusions, and the soda glass.

[0062] 14 and 15 show the temperature response under the above conditions. １ , a ２ is the thermal conductivity k １ , k ２ The temperature response ΔT of known brass (k = 123 W / mK) and stainless steel (SUS, k = 16 W / mK) １ (t), ΔT ２ It can be seen that when aluminum, which has good thermal conductivity, is used as an inclusion, the temperature response is smaller than when there are no inclusions, and when soda glass, which has poor thermal conductivity, is used as an inclusion, the temperature response is larger.

[0063] Figure 16 shows the time change in equivalent thermal conductivity k(t) calculated using the first thermophysical property calculation method based on the simulation results of Figures 8, 14, and 15. Focusing on the data for the substrate material (carbon steel) alone, it can be seen that k(t) gradually approaches the set value of k = 43. When there are aluminum inclusions with high thermal conductivity, k(t) is calculated to be large, and when there is soda glass with low thermal conductivity, k(t) is calculated to be small. When the inclusions are close to the temperature measurement device, their influence becomes greater.

[0064] Figure 17 shows the difference obtained by subtracting the equivalent thermal conductivity of the substrate material (carbon steel) alone from the equivalent thermal conductivity including the inclusion. The effect of the inclusion is the same as in Figure 16, but it can be seen that the closer the inclusion is to the temperature measurement device, the more pronounced its effect becomes at the beginning of the measurement.

[0065] Example 4 As Example 4, a thermophysical property measurement using the second thermophysical property value calculation method will be described with reference to FIGS. 18 and 19. FIG.

[0066] FIG. 18 shows the change over time in the equivalent thermal conductivity k(t) of carbon steel when brass, stainless steel (SUS), and tungsten are used as standard materials, and FIG. 19 shows the change over time in the equivalent thermal diffusivity α(t) of carbon steel when brass and stainless steel (SUS) are used as standard materials.

[0067] The second thermophysical property calculation method is a method for determining the equivalent thermal conductivity of a material to be measured using three types of standard materials. Fig. 18 shows an example in which the equivalent thermal conductivity of carbon steel is calculated from the thermophysical property values ​​of three materials used as standard materials, assuming the second thermophysical property calculation method. Fig. 19 shows an example in which the equivalent thermal diffusivity of carbon steel is calculated, assuming the fourth thermophysical property calculation method. The equivalent thermal conductivity of carbon steel is calculated using set values ​​(k = 43 W / mK, α = 1.18 × 10 －７ m / s ２ ) is approaching. Although it depends on the thermophysical properties of the measured substance, using three or more reference materials, as in the example of Figure 18, may improve the accuracy of measuring the thermophysical properties of the measured substance. Furthermore, it is thought that measuring many reference materials and using the third thermophysical property calculation method will improve the accuracy of calculating the thermophysical properties of the target substance.

[0068] Fifth Embodiment As a fifth embodiment, a method for identifying the distance between an inclusion and a temperature measuring device that applies a heat pulse will be described with reference to FIGS. 20 and 21. FIG.

[0069] In Examples 1 to 4, it became clear that the time change in equivalent thermal conductivity depends on the size and thermal properties of the inclusion, but it was difficult to clearly identify the position of the inclusion. In Example 5, a method for identifying the distance between the inclusion and the sensor that applies the heat pulse will be described with reference to Figures 20 and 21.

[0070] Figure 20 shows the time difference value change of the equivalent thermal conductivity k organized by the position of the inclusion and the characteristic length L, and the position of the inclusion (skin model), and Figure 21 shows the time difference value change of the equivalent thermal conductivity k organized by the position of the inclusion and the characteristic length L, and the position of the inclusion (metal / inorganic material model).

[0071] The thermal conductivity k can be converted to units of length using equation (9).

[0072] Here, the thermal diffusivity α is calculated as follows using the thermal conductivity k: α = k / (c ｐ ρ) where C is the equipment constant.

[0073] Figure 20 shows the time-differentiated difference dk / dt between the equivalent thermal conductivity k(t) with the inclusion (fat layer) shown in Figure 12 and the equivalent thermal conductivity k(t) of the medium (dermis) alone, organized by the characteristic length L when the equipment constant C in equation (9) is set to 1.3. The position of the top of the inclusion (fat layer) and the position where the characteristic curve rises are almost the same. In this example, it can also be seen that the position where the fat layer disappears and the maximum value of the time difference are almost the same.

[0074] Like Fig. 20, Fig. 21 summarizes the time derivatives for the metal and inorganic materials shown in Fig. 17 with respect to the characteristic length L. As in Fig. 20, the positions of inclusions and the positions where the time derivative of equivalent thermal conductivity changes coincide. As described above, by measuring the shapes and thermal property values ​​of inclusions, it may be possible to estimate the position, depth, size, and thermal property values ​​of the inclusions.

[0075] As described above, according to this embodiment, by calculating the thermophysical property values ​​over time, it is possible to distinguish differences in thermophysical properties near the surface, which were not possible with conventional methods. For example, it is possible to clarify skin cancer in an abnormal area that remains in the epidermis based on differences in thermophysical properties. Furthermore, if the substance being measured is a biological component, is skin or a superficial tissue close to the skin, and the abnormal area is a cancerous lesion, it is possible to non-invasively determine the stage of the cancer.

[0076] On the other hand, when the substance to be measured is food, agricultural or marine products, or industrial products, the time change of the thermal properties of the food or industrial product can be compared between an abnormal item suspected of containing an abnormal substance or a defective material and a normal item not containing an abnormal substance or a defective material, thereby making it possible to non-invasively determine the presence or absence and size of impurities or defects inside the food or industrial product.

[0077] The difference in the time change of the thermal property values ​​between the abnormal part and the normal part inside the measured substance is expressed as a difference converted into length, and the position and size of the abnormal part inside the measured substance can be identified.Furthermore, the difference in the time derivative of the time change of the thermal property values ​​between the abnormal part and the normal part inside the measured substance is expressed as a difference converted into length, and the position and size of the abnormal part inside the measured substance can be identified.

[0078] Since heat propagates from the heated area to the interior over time, information about depth can be obtained by calculating the changes in thermal properties over time, as in this embodiment. For example, the layer structure inside the skin can be clarified by observing the changes over time in equivalent thermal conductivity, etc.

[0079] Furthermore, when a foreign object with different thermal properties exists inside a substance, the position (depth and size) of the foreign object can be estimated non-invasively by the thermal property measurement method and object interior exploration method of this embodiment. For example, in the case of skin cancer, the depth of cancer penetration can be estimated from the time change of the equivalent thermal conductivity, etc., which not only reveals the stage of cancer but also serves as a guideline for how deep the cancer should be removed.

[0080] Furthermore, the measurement targets can be applied not only to living organisms such as skin cancer, but also to industrial materials such as metal materials, plastics, and ceramics, as well as food.

[0081] The present invention is not limited to the configurations of the above-described embodiments, and various modifications are possible within the scope of the invention. Furthermore, the above-described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

[0082] DESCRIPTION OF SYMBOLS 1 Thin film temperature sensing element for measurement 2 Thin film temperature sensing element for protective heating 3 Temperature control element 4 Shaft 10 Temperature measurement device (thermal pulse radar) 11 Substrate 12 Thin film element layer 31 Heat sink 32 Thin film temperature sensing element 33 Heat dissipation fin 41 Temperature sensing section

Claims

1. A temperature measurement method for heating a substance to be measured whose thermophysical properties are unknown under constant heating conditions and measuring the temperature of the heating surface, comprising the steps of: recording the temperature response of at least two standard substances with known thermophysical properties during heating in time series; determining parameter values ​​derived from at least two temperature measurement devices for each hour to calculate the thermophysical properties of the substance to be measured using the time-series recorded data; subsequently measuring the temperature response of the substance to be measured in time series as the temperature changes; and determining the thermophysical properties of the substance to be measured for each hour using the time-series measurement data of the substance to be measured and the parameter values ​​for each hour.

2. The temperature measuring method according to claim 1, wherein the thermophysical property value is equivalent thermal conductivity.

3. The temperature measuring method according to claim 1, wherein the thermophysical property value is equivalent thermal diffusivity.

4. A method for calculating thermophysical properties in which a substance to be measured whose thermophysical properties are unknown is heated under constant heating conditions and the temperature of the heating surface is measured, comprising the steps of: recording the temperature response of at least two standard substances with known thermophysical properties during heating in time series; determining parameter values ​​derived from at least two temperature measurement devices for each hour to calculate the thermophysical properties of the substance to be measured using the time-series recorded data; subsequently measuring the temperature response of the substance to be measured as the temperature changes in time series; and determining the thermophysical properties of the substance to be measured for each hour using the time-series measurement data of the substance to be measured and the parameter values ​​for each hour.

5. The method for calculating a thermophysical property value according to claim 4, wherein the thermophysical property value is an equivalent thermal conductivity.

6. The method for calculating a thermophysical property value according to claim 4, wherein the thermophysical property value is an equivalent thermal diffusivity.

7. The thermophysical property calculation method according to claim 4, characterized in that there are two standard materials and two parameter values.

8. The thermophysical property calculation method according to claim 4, wherein the number of said standard substances and said parameter values ​​is three or more.

9. The method for calculating thermophysical properties according to claim 4, wherein the known thermophysical properties of the standard material are thermal conductivity, specific heat, and density.

10. A method for examining the inside of an object, in which a substance to be measured whose thermophysical properties are unknown is heated under constant heating conditions and the temperature of the heating surface is measured, comprising the steps of: recording the temperature response of at least two standard substances with known thermophysical properties when heated in time series; determining parameter values ​​derived from at least two temperature measurement devices for each time period for calculating the thermophysical properties of the substance to be measured using the time-series recorded data; subsequently measuring the temperature response of the substance to be measured in time series as the temperature changes; determining the thermophysical properties of the substance to be measured for each time period by using the time-series measurement data of the substance to be measured and the parameter values ​​for each time period; and comparing the time-series changes in the thermophysical properties of the substance to be measured at multiple points to determine the presence or absence of an abnormality inside the substance to be measured and the size of such an abnormality.

11. The method for examining the interior of an object according to claim 10, wherein the thermophysical property value is equivalent thermal conductivity.

12. The method for examining the interior of an object according to claim 10, wherein the thermophysical property value is an equivalent thermal diffusivity.

13. A method for exploring the interior of an object according to any one of claims 10 to 12, characterized in that the substance to be measured is a biological component, and the time change in the thermal property value of the biological component is compared between an abnormal part and a healthy part in the vicinity thereof to determine the abnormal part inside the biological component.

14. A method for exploring the interior of an object according to claim 13, wherein the biological component is skin or superficial tissue close to the skin, the abnormal part is a cancerous lesion, and the stage of the cancer is determined.

15. A method for exploring the interior of an object according to any one of claims 10 to 12, characterized in that the substance to be measured is a food product, agricultural or marine product, or industrial product, and the presence or absence and size of impurities or defects inside the substance to be measured are determined by comparing the time changes in the thermophysical properties of the substance to be measured between an abnormal item suspected of containing an abnormal substance or a material defect and a normal item not containing an abnormal substance or a material defect.

16. A method for exploring the interior of an object according to any one of claims 10 to 12, characterized in that the difference in the time change of the thermophysical property values ​​between the abnormal part and the normal part inside the measured material is expressed as a difference converted into length, and the position and size of the abnormal part inside the measured material are identified.

17. A method for exploring the interior of an object according to any one of claims 10 to 12, characterized in that the difference in the time derivative of the thermal property value of an abnormal part and a normal part inside the measured material with respect to the time change is expressed as a difference converted into length, and the position and size of the abnormal part inside the measured material are identified.

18. A method for exploring the interior of an object according to claim 16 or 17, characterized in that the change in the thermal property value over time is converted into length L using the following formula, where C is the device constant, α is the thermal diffusivity, and t is the time.

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