JP5345574B2 - Measuring method of principal axis thermal constant of two-dimensional anisotropic heat conducting material using multi-point temperature measurement by pulse / periodic method and measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for accurately measuring values of the principal-axis thermophysical properties of a two-dimensional anisotropic heat conductor by using pulses or a heat source which periodically changes, and to provide a measuring apparatus thereof. <P>SOLUTION: In the method for measuring a principal-axis thermal constant of the two-dimensional anisotropic heat conductor using multi-point temperature measurement by a pulse/period method, a spot-like heat source 2 capable of changing over heating and heat absorption is brought into contact with the surface of an object 1 to be measured, the two-dimensional anisotropic heat conductor to heat and absorb heat from the surface of the object 1 to be measured by the spot-like heat source 2. Temperature-measuring elements 3 arranged at a plurality of locations on the surface of the object 1 to be measured measure phase differences and temperature differences of temperature waves in a non-stationary state that the temperature field of the object 1 to be measured changes or in a stationary state that the temperature field does not change to measure values of the principal-axis thermophysical properties such as principal-axis thermal conductivity; principal axis thermal diffusivity; and the specific heat of the object 1 to be measured. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for measuring principal axis thermal conductivity, principal axis thermal diffusivity, and principal axis angle, which are principal axis thermophysical properties of a two-dimensional anisotropic thermal conductive material, and a measuring apparatus for measuring these.

  It is important to establish a method for separating and measuring an efficient and highly accurate principal axis thermal property value (such as principal axis thermal conductivity, principal axis thermal diffusivity, etc.) of a two-dimensional anisotropic thermal conductive material (see Patent Document 1).

  In the conventional separation measurement method of principal axis thermophysical values (main axis thermal conductivity, principal axis thermal diffusivity, etc.) of two-dimensional anisotropic heat conducting materials, it was measured using a constant output heat source. It was difficult to accurately determine the thermal conductivity of the spindle and the thermal diffusivity of the spindle simultaneously from the temperature distribution.

JP 2005-214858 A

  The present invention solves the problems of conventional measurement methods, and by using a heat source that changes in a pulse or periodically, the main axis thermophysical value of the two-dimensional anisotropic heat conductive material (main axis It is an object of the present invention to provide a method for accurately measuring a thermal conductivity, a spindle thermal diffusivity, and the like and a measuring apparatus therefor.

  The gist of the present invention will be described with reference to the accompanying drawings.

A point heat source 2 connected to a Peltier element 8 and configured to be switchable between heating and heat absorption is brought into contact with the surface of the object 1 to be measured, which is a two-dimensional anisotropic heat conductive material or a two-dimensional isotropic heat conductive material. Then, a periodic current such as a pulse current or a sin function or a cos function is applied to the Peltier element 8 so that the surface of the object 1 to be measured is heated or absorbed by the point heat source 2 in a pulsed manner or periodically. A temperature measuring element 3 is disposed on the surface of the object 1 at equal intervals in the measurement axis direction with a plurality of radiation directions that are equiangular with respect to the point-like heat source 2 as the measurement axis direction. The phase difference and the temperature difference of the temperature wave at each measurement point in the unsteady state where the temperature field changes or the steady state where the temperature field does not change are measured, and the measured thermal conductivity in the direction of each measurement axis is measured as the point heat source 2. Per unit time It is represented by the amount of heat flowing, the logarithmic ratio of the distance from the point heat source 2 to each measurement point in the radial direction of the measurement, the thickness of the object 1 to be measured, and the temperature difference between the measurement points. Calculated by Q · ln (r ₂ / r ₁ ) / (2πhΔT), and the measured thermal diffusivity in the direction of each measurement axis is expressed by the phase difference with respect to the time of the temperature wave of the period represented by the pulse period or periodic function. TΔr ² / (4πτ ² ), and from these measured thermal conductivity and measured thermal diffusivity, the two principal axis thermal conductivities, the two principal axis thermal diffusivities, the principal axis angle and the specific heat of the measured object 1 are measured. The present invention relates to a principal axis thermal constant measurement method for a two-dimensional anisotropic thermal conductive material using multipoint temperature measurement by a pulse / period method.

  Further, three temperature measuring elements 3 are arranged at equal intervals in the measurement axis direction with three radiation directions of 0 °, 120 °, and 240 ° centered on the point heat source 2 as measurement axis directions. The principal axis thermal constant measurement method for a two-dimensional anisotropic thermal conductive material using multipoint temperature measurement by a pulse / period method according to claim 1.

  The Peltier element 8 is supplied with a periodic current such as a pulse current or a sin function, a cos function, etc. so that the point heat source 2 repeats heating and heat absorption on the surface of the object 1 to be measured. The application condition is set, and two principal axis thermal conductivities, two principal axis thermal diffusivities, principal axis angles and specific heat of the object to be measured 1 are simultaneously measured using an absolute method. The present invention relates to a principal axis thermal constant measurement method for a two-dimensional anisotropic thermal conductive material using multipoint temperature measurement by the pulse / period method described in any one of the items.

Further, by measuring the phase difference and temperature difference of the temperature wave at each measurement point in the unsteady state where the temperature field of the measured object 1 changes or in the steady state where the temperature field does not change, the two main axes of the measured object 1 are measured. A principal axis thermal constant measuring device for a two-dimensional anisotropic thermal conductive material using multi-point temperature measurement by pulse / periodic method to measure thermal conductivity, two principal axis thermal diffusivities, principal axis angle and specific heat, and a Peltier element 8 and a point-like heat source 2 configured to be switchable between heating and heat absorption, and the temperature wave of each measurement point in a non-steady state where the temperature field of the object to be measured 1 changes or a steady state where the temperature field does not change A temperature measuring element 3 for measuring a phase difference and a temperature difference, and a phase difference and a temperature difference of a temperature wave having a period represented by a pulse period or a periodic function with respect to time at each measurement point where the temperature measuring element 3 is arranged. Heat transfer in the measuring axis direction An actual measurement value calculation unit 16 for calculating a thermal conductivity and a thermal diffusivity as an actual measurement value. The actual measurement value calculation unit 16 calculates the actual thermal conductivity on each measurement axis from the point heat source 2 per unit time. Q · ln (r ₂₎ expressed by the amount of heat flowing to the point, the logarithmic ratio of the distance from the point heat source 2 to the measurement point on the radial line, the thickness of the object 1 to be measured, and the temperature difference of the measurement point / r ₁₎ / (means for calculating the 2πhΔT), tΔr said measured thermal diffusivity on each measurement axis, represented by a phase difference with respect to time of the temperature wave period represented by the pulse period or periodic function ² The present invention relates to an apparatus for measuring the principal axis thermal constant of a two-dimensional anisotropic heat conducting material using multipoint temperature measurement by a pulse / period method, characterized by comprising means for calculating by / (4πτ ² ) .

  Further, three temperature measuring elements 3 are arranged at equal intervals in the measurement axis direction with three radiation directions of 0 °, 120 °, and 240 ° centered on the point heat source 2 as measurement axis directions. 5. The apparatus according to claim 4, wherein the main-axis heat constant measuring device for a two-dimensional anisotropic heat conducting material using multi-point temperature measurement by a pulse / periodic method.

Further, a periodic current such as a pulse current or a sin function or a cos function is applied to the Peltier element 8 so that the point-like heat source 2 is represented by a pulse period or a periodic function with respect to the surface of the object 1 to be measured. The application condition of heat flux that repeats heating and endotherm is set at, and the two principal axis thermal conductivities, the two principal axis thermal diffusivities, the principal axis angle and the specific heat of the measured object 1 are measured simultaneously using the absolute method. 6. The apparatus for measuring the principal axis thermal constant of a two-dimensional anisotropic heat conducting material using multi-point temperature measurement by the pulse / period method according to claim 4 or 5 , characterized by comprising: It is.

  Since the present invention is configured as described above, it is possible to measure the spindle thermal physical properties (spindle thermal conductivity, spindle thermal diffusivity, etc.) of the two-dimensional anisotropic thermal conductive material with high efficiency and high accuracy.

  Further, by measuring the principal axis thermophysical property of the two-dimensional anisotropic heat conductive material, it is possible to easily distinguish it from the two-dimensional isotropic heat conductive material. That is, for example, a two-dimensional anisotropic thermal conductive material usually has two different values of principal axis thermal conductivity, but in the case of a two-dimensional isotropic thermal conductive material, this value is the same and the value is one. It can be easily identified by connecting.

It is explanatory drawing which shows the arrangement | positioning condition of the temperature measurement element with respect to the point-like heat source of the two-dimensional anisotropic heat conductive material of a present Example. It is an explanatory outline figure showing a point heat source of this example, a Peltier device, and a sample holder part. It is a block diagram of the measuring apparatus which measures the principal-axis thermophysical property value and principal-axis angle of the two-dimensional anisotropic heat conductive material of a present Example.

  An embodiment of the present invention which is considered to be suitable will be briefly described with reference to the drawings showing the operation of the present invention.

  In the measuring method according to the present invention, for example, a point-like heat source 2 is formed by attaching a metal plate 9 such as thin copper of the same area on one side of a Peltier element 8 as a heat source and welding a thin metal rod 10 on this surface. The tip of the point heat source 2 in a state where a periodic current such as a pulse current or a sin function or a cos function is passed through the Peltier element 8 serving as a heat source of the point heat source 2 is covered with a two-dimensional anisotropic heat conductive material. In order to diffuse heat uniformly around one heat source point that is brought into contact with the surface of the object to be measured 1 and in contact with the surface of the object 1 to be measured, the heat reflects the characteristics of the two-dimensional anisotropic heat conductive material. The phase difference of the temperature wave in the unsteady state where the temperature field changes or in the steady state where the temperature field does not change from the temperature distribution on the surface of the two-dimensional object 1 to be measured considering the anisotropic characteristics. And measuring the temperature difference Spindle thermal conductivity of the original anisotropic thermal conductive material, the spindle thermal diffusivity measures the spindle thermal physical properties such as specific heat.

  The measuring apparatus according to the present invention has, for example, a Peltier element 8 connected to a rod-shaped metal body 10 having a fixed shape, and this rod-shaped metal body 10 becomes a point heat source 2 on the surface of the object 1 to be measured which is in point contact. A heat flow field in which heat flows is formed, and nine temperature measurement points are provided at three equidistant positions (for example, 120 ° intervals) at three positions away from the point-like heat source 2 at the same interval. Measure phase difference and temperature difference of temperature wave in unsteady state where temperature field changes or steady state where temperature field does not change, and measure thermal conductivity and thermal diffusivity in three directions at equal intervals. The main axis direction is calculated from the measured values, and finally, the main axis thermal conductivity, the main axis thermal diffusivity, and the main axis angle are measured.

  Further, for example, in the temperature measurement at each temperature measurement point set on the surface of the two-dimensional anisotropic material, the amount of heat applied by the point heat source 2 is heated, absorbed, and diffused by the object 1 to be measured. For example, in the experiment, the entire object to be measured 1 and the point-like heat source 2 are covered with the holder 11 in order to prevent heat leakage loss of the two-dimensional anisotropic heat conductive material.

  Also, for example, when measuring with higher accuracy in measuring the thermophysical properties of the spindle, nine measurement temperature point temperatures on the surface of the object 1 to be measured by the point heat source 2 are measured at a high resolution temperature of mK. Although necessary, this apparatus sufficiently satisfies this requirement, and is provided with means for measuring and calculating the principal axis physical property value of the two-dimensional anisotropic heat conductive material.

  Therefore, according to the present invention, a periodic current represented by, for example, a pulse current or a periodic function is applied to the Peltier element 8 by the point-like heat source 2 set directly on the surface of the measured object 1 which is a two-dimensional anisotropic heat conductive material. A situation where the generated heat is applied from the point-like heat source 2 having a small area to the surface of the object 1 to be measured and the heat diffuses on the surface of the object 1 to be measured and the inside thereof is, for example, unidirectional The temperature is measured as a function of time by means of temperature measuring elements 3 installed at three equal intervals, and the geometrical relationship is used to determine the direction of the principal axis angle from the three directions of thermal conductivity and thermal diffusivity. The two main shaft thermal conductivities and the two main shaft thermal diffusivities can be directly determined.

  A specific embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, a point heat source 2 that can be switched between heating and heat absorption by the Peltier element 8 is brought into contact with the surface of the object 1 to be measured, which is a two-dimensional anisotropic heat conductive material or a two-dimensional isotropic heat conductive material. The surface of the measured object 1 is brought into contact with the point-like heat source 2 by periodically applying a pulsed current or a periodic current such as a sin function or a cos function to the Peltier element 8 to heat and absorb the surface of the measured object 1. The temperature measurement elements 3 arranged in a plurality of locations in the temperature measurement element 3 measure the phase difference and temperature difference of the temperature wave in the unsteady state where the temperature field of the measured object 1 changes or in the steady state where the temperature field does not change. 1 is a method for measuring the principal axis thermal constant of a two-dimensional anisotropic thermal conductive material using multi-point temperature measurement by a pulse-periodic method for measuring principal axis thermal physical properties such as principal axis thermal conductivity, principal axis thermal diffusivity, and specific heat.

  First, a two-dimensional thermophysical property measuring unit, a measuring device, and an overall view of the measuring device for measuring the principal axis thermal conductivity, the principal axis thermal diffusivity, and the principal axis angle of the two-dimensional anisotropic thermal conductive material of this example, respectively, A description will be given with reference to FIGS.

FIG. 1 shows a point heat source 2 of a main axis thermal constant measuring device for a two-dimensional anisotropic heat conducting material by the heat flow meter type multi-point temperature measurement method, and nine temperature measurement points (point (a) to point ( ) Is shown at the positions of r ₁ , r ₂ , r ₃ ). The attachment position of the thermocouple 3 as the temperature measuring element 3 is shown as a case where the angle α is α = 120 °, but three different axes on the same angle of α = 120 °, that is, the thermocouple installation axis L ₁ (0 °) 4, Thermocouple installation axis L ₂ (120 °) 5, Thermocouple installation axis L ₃ (240 °) 6 Measured thermal conductivity ( By obtaining the formula (1)) and the measured thermal diffusivity (formula (8)), two different main shaft thermal conductivities (formula (4), formula (5)), main shaft thermal diffusivity (formula (11)) , Equation (12)) and the spindle angle position φ _λ (equation (7)) can be measured simultaneously.

  FIG. 2 shows details of the point heat source 2, the Peltier element 8, and the sample holder.

  Specifically, a metal plate 9 such as thin copper having the same area is attached to one side of the Peltier element 8 and a thin cylindrical metal rod 10 is welded on this surface to constitute the point heat source 2. In order to prevent heat leakage loss of the two-dimensional anisotropic heat conducting material, the point heat source 2 is erected on the sample 1 so that the tip of the heat source 2 contacts the surface of the sample 1 (object 1 to be measured). The entire sample 1 and the point-like heat source 2 are covered with a holder 11.

  Further, a periodic current such as a pulse current or a sin function or a cosine function is periodically applied to the Peltier element 8 provided in the point-shaped heat source 2 configured as described above by the Peltier element power source 14 to the point-like heat source 2. An inflow heat quantity Q is generated, and heat is applied to the surface of the sample 1 which is a two-dimensional anisotropic heat conductive material.

  This inflow heat quantity Q is obtained from the Fourier law by measuring the temperature at the temperature measurement point (co) and the temperature measurement point (sa) with the heat flow meter 7 and using the known thermal conductivity of the cylindrical metal body 10. Can be sought.

  Further, since the surface of the sample 1 reduces heat loss due to convection, the point heat source 2, the Peltier element 8 and the sample holder part can be covered with the heat insulating material 12, and the measurement accuracy of the principal axis thermophysical property value can be improved.

  FIG. 3 shows an overall schematic diagram of the measuring apparatus. After placing the sample 1 which is a two-dimensional anisotropic heat conductive material on the sample mounting table 13 and covering the entire object to be measured 1 with the holder 11, the sample 1 is locally pulsed using the point heat source 2. The temperature and phase temperature changes of the nine thermocouples 3 that are periodically heated and absorbed by the period represented by the periodic function and placed on the surface of the sample 1 are measured using the multi-thermometer 15, and these The measurement data is stored in the computer 16 as the actual measurement value calculation unit 16.

  The measured values of these temperature changes are immediately analyzed and displayed by the computer 16 as the main axis thermal conductivity, main axis thermal diffusivity, specific heat, and main axis angle of the two-dimensional anisotropic heat conductive material. .

  Further, by using the measurement method and the measurement apparatus described above, heating and endotherm are performed by the Peltier element 8 at the center of the 3 sets × 3 pairs of thermocouples 3 installed on the surface of the sample 1 which is a two-dimensional anisotropic heat conductive material. The point-like heat source 2 that can be switched to is installed, and a periodic current such as a pulse current or a sin function or a cos function is supplied to the Peltier element 8 by a periodic function such as a pulse period or a sin function or a cos function. The heat of the point-like heat source 2 generated in a period is added, and this heat diffuses to show an unsteady temperature distribution or a steady temperature distribution reflecting the characteristics of the two-dimensional anisotropic heat conductive material. It is theoretically shown below that the principal axis thermal conductivity and the principal axis thermal diffusivity of the two-dimensional anisotropic thermal conductive material can be separated and measured simultaneously by measuring the change or distribution state.

  The one-way thermal conductivity of the three pairs of thermocouples can be expressed by equation (1) of the distance from the point-like heat source 2 of the thermocouple 3 and the measured temperature difference in the steady state. The measured temperature has a period, and the measured temperature difference is obtained by using a value obtained by removing this period by Fourier transform or first-order approximation.

Here, Q: the amount of heat supplied from the point-like heat source 2, h: thickness of the sample of the two-dimensional anisotropic heat conductive material, λ _i : measured thermal conductivity in the measurement axis direction, r ₁ , r ₂ : temperature Indicates the radius to the measurement position.

  In general, using the thermal conductivities on the three measurement axes, the principal axis thermal conductivity is calculated by the following formula (2).

Here, λ _{p1 is} one principal axis thermal conductivity, α is an angle between three measurement axes, and λ ₁ , λ ₂ , and λ ₃ are measured values of thermal conductivity on the three axes.

Similarly, λ _P2 is calculated by the following equation (3).

Here, λ _p2 represents the other principal axis thermal conductivity.

In particular, the thermal conductivity at 0 °, 120 °, and 240 ° obtained experimentally by the equation (1) represents the thermophysical value of the two-dimensional anisotropic heat conductive material. The main spindle thermal conductivity λ _P1 is calculated by the equation (4).

Similarly, λ _P2 is calculated by the following equation (5).

Further, the principal axis angle φ _λ of the two-dimensional anisotropic heat conductive material is generally obtained by the equation (6).

Here, phi _lambda main axis angle determined by experimentally three measured thermal conductivity lambda ₁ of the measuring _axis, lambda _2, lambda _3, the lambda _k1, lambda _k2 are constants.

In particular, the principal axis angle φ _λ at 0 °, 120 °, and 240 ° is obtained by Equation (7).

  On the other hand, by measuring the temperature at 9 points of 0 °, 120 ° and 240 °, the time delay is obtained from the phase difference of the temperature wave in the unsteady state, and each of these axes is calculated using the following equation (8). The thermal diffusivity in the direction can be determined.

Here, Δr: distance between installed thermocouples represented by r ₂ -r ₁ or r ₃ -r ₂ , t: period of heat source, τ: time delay of two temperature waves, κ _i : actual measurement in measurement axis direction The measured value of thermal diffusivity is shown.

  Generally, using the thermal diffusivities on the three measurement axes, the principal axis thermal diffusivity is calculated by the following equation (9).

Here, κ _p1 : one main axis thermal conductivity, κ ₁ , κ ₂ , κ ₃ : actual measured values of thermal diffusivity in three measurement axes.

Similarly, the other main shaft thermal diffusivity κ _P2 can be obtained by the following equation (10).

Here, λ _p2 is the other principal axis thermal conductivity.

In particular, one main axis thermal diffusivity κ _P1 can be obtained from the measured values of thermal diffusivity at 0 °, 120 °, and 240 ° using the following equation (11).

Similarly, the other principal axis thermal diffusivity κ _P2 can be obtained by the following equation (12).

  Further, the specific heat of the object to be measured can be calculated from the principal axis thermal conductivity and the principal axis thermal diffusivity by the following equation (13).

  Here, c is the specific heat and ρ is the sample density.

  According to the calculation formula of the main shaft thermal conductivity, the formula (4), the formula (5), the calculation formula of the main shaft thermal diffusivity, the formula (11), the formula (12), the calculation formula of the main shaft angle, the formula (7). It becomes possible to measure the principal axis thermal conductivity, the principal axis thermal diffusivity, and the principal axis angle of the two-dimensional anisotropic heat conductive material with high accuracy.

  Therefore, in this embodiment, the point heat source 2 capable of switching the heat absorption by the Peltier element 8 is brought into contact with the surface of the sample 1 which is a two-dimensional anisotropic heat conductive material, and the pulse current or sin is applied to the Peltier element 8. The heat of the point heat source 2 generated by applying a periodic current such as a function or a cos function to generate a pulse period or a period represented by a periodic function such as a sin function or a cos function is diffused. By measuring the temperature distribution change state in the unsteady state or steady state reflecting the characteristics of the two-dimensional anisotropic heat conducting material, the principal axis thermal conductivity and the principal axis thermal diffusivity of the two-dimensional anisotropic heat conducting material are determined. This provides a method and apparatus for measuring principal axis thermophysical properties (principal thermal conductivity, principal axis thermal diffusivity, etc.) of a two-dimensional anisotropic thermal conductive material that can be separated and measured simultaneously with high accuracy.

  Note that the present invention is not limited to this embodiment, and the specific configuration of each component can be designed as appropriate.

DESCRIPTION OF SYMBOLS 1 Object to be measured 2 Point heat source 3 Temperature measuring element 8 Peltier element
16 Actual value calculation unit

Claims (6)

A point heat source configured to connect a Peltier element and switch between heating and heat absorption is brought into contact with the surface of the object to be measured, which is a two-dimensional anisotropic heat conductive material or a two-dimensional isotropic heat conductive material, and the Peltier A pulse current or a periodic current such as a sin function or a cos function is applied to the element to heat or absorb the surface of the object to be measured in a pulsed manner or periodically by the point heat source. A temperature measuring element in which a plurality of radiation directions that are equiangular with each other around a point heat source are set as measurement axis directions at equal intervals in the measurement axis direction, and the temperature field of the object to be measured changes in an unsteady state or Measure the phase difference and temperature difference of the temperature wave at each measurement point in the steady state where the temperature field does not change, and measure the measured thermal conductivity in the direction of each measurement axis from the point heat source. It said measuring axis direction said is this radial direction from the source log ratio of the distance to each measurement point, the thickness of the object to be measured, and represented by the above temperature difference between measurement points Q · ln (r _{2 /} r ₁ ) / (2πhΔT) and the measured thermal diffusivity in each measurement axis direction is represented by a phase difference with respect to time of a temperature wave having a period represented by a pulse period or a periodic function, tΔr ² / (4πτ ² ) The two main axis thermal conductivities, two main axis thermal diffusivities, the main axis angle and the specific heat of the measured object are measured from these measured thermal conductivity and measured thermal diffusivity. Measurement method of principal axis thermal constant of two-dimensional anisotropic heat conducting material using multi-point temperature measurement by the method.   3. The temperature measuring elements are arranged three by three at equal intervals in the measurement axis direction, with three radiation directions of 0 °, 120 °, and 240 ° centered on the point heat source as measurement axis directions. A method for measuring a principal axis thermal constant of a two-dimensional anisotropic thermal conductive material using multipoint temperature measurement by the pulse / period method according to Item 1.   By applying a periodic current such as a pulse current or a sin function or a cos function to the Peltier element, a condition for applying a heat flux in which the point heat source repeatedly heats and absorbs heat on the surface of the object to be measured is set. The two principal axis thermal conductivities, the two principal axis thermal diffusivities, the principal axis angle, and the specific heat of the object to be measured are measured simultaneously using an absolute method. Of principal axis thermal constant of two-dimensional anisotropic heat conducting material using multi-point temperature measurement by pulse / periodic method. Measuring the phase difference and temperature difference of the temperature wave at each measurement point in the unsteady state where the temperature field of the measured object changes or in the steady state where the temperature field does not change, and the two principal axis thermal conductivities of the measured object, A main axis thermal constant measuring device for two-dimensional anisotropic heat conducting material using multi-point temperature measurement by pulse / periodic method to measure two main axis thermal diffusivity, main axis angle and specific heat, heating by connecting Peltier element measured and the and the point-like heat source configured to be switched to the heat absorption, the phase difference and the temperature difference between the temperature wave of the measurement points in a steady state in which no change in the non-steady-state or the temperature field changes in temperature field of the object to be measured Thermal conductivity and heat in each measurement axis direction using the temperature measurement element and the phase difference and temperature difference of the temperature wave of the period represented by the pulse period or periodic function with respect to the time of each measurement point where the temperature measurement element is arranged Realize diffusion rate An actual value calculation unit that calculates the value, and the actual value calculation unit radiates the actual heat conductivity on each measurement axis from the point heat source and the amount of heat flowing from the point heat source per unit time. Means for calculating by Q · ln (r ₂ / r ₁ ) / (2πhΔT) expressed by the logarithmic ratio of the distance to the measurement point on the direction line, the thickness of the measured object, and the temperature difference of the measurement point And means for calculating the measured thermal diffusivity on each measurement axis by tΔr ² / (4πτ ² ) represented by a phase difference with respect to time of a temperature wave having a period represented by a pulse period or a periodic function. An apparatus for measuring the principal axis thermal constant of a two-dimensional anisotropic heat-conducting material using multipoint temperature measurement by the pulse / period method.   3. The temperature measuring elements are arranged three by three at equal intervals in the measurement axis direction with three radiation directions of 0 °, 120 °, and 240 ° centered on the point heat source as measurement axis directions. Item 5. An apparatus for measuring the principal axis thermal constant of a two-dimensional anisotropic thermal conductive material using multipoint temperature measurement by the pulse / period method according to Item 4. A pulse current or a periodic current such as a sin function or a cos function is applied to the Peltier element so that the point-like heat source is heated and absorbed by a pulse period or a period represented by a periodic function with respect to the surface of the object to be measured. The heat flux application condition is repeated, and the two principal axis thermal conductivities, the two principal axis thermal diffusivities, the principal axis angle and the specific heat of the measured object are measured simultaneously using the absolute method. An apparatus for measuring a principal axis thermal constant of a two-dimensional anisotropic thermal conductive material using the multipoint temperature measurement by the pulse / period method according to any one of claims 4 and 5 .