CN221124395U - Device for measuring in-plane thermophysical quantity of film - Google Patents

Abstract

The utility model discloses a device for measuring thermal physical quantities within a film surface, wherein the measuring device is applied to the measurement of thermal conductivity within a self-supporting film surface, the measurement of thermal diffusivity within a surface, and the measurement of volume heat capacity, and the measuring device comprises: a triple frequency signal acquisition box, a double frequency signal acquisition box, a data acquisition module, and a control module; the triple frequency signal acquisition box comprises an AC current source module, a baseband signal elimination circuit, a first secondary amplifier, a first matrix switch, and a sampling resistor; the double frequency signal acquisition box comprises a DC/AC constant current source module, a DC signal elimination circuit, a second secondary amplifier, and a second matrix switch. The technical solution of the embodiment of the utility model realizes the simultaneous acquisition of the triple frequency voltage signal on the first conductive strip and the double frequency voltage signal on the second conductive strip, and eliminates the baseband voltage signal and the DC voltage signal, thereby realizing the efficient and accurate measurement of thermal physical quantities within the film surface.

Description

A device for measuring thermal physical quantities in a film surface

Technical Field

The utility model relates to the technical field of thermal property measurement, in particular to a device for measuring thermal physical quantities within a film surface.

Background technique

In the process of developing functional films such as thermoelectric films and phase change films, it is necessary to systematically characterize their thermal physical properties such as thermal conductivity and thermal diffusivity. When measuring the thermal conductivity of the film surface, an AC heating current of a certain frequency is passed through the first conductive strip, and a DC detection current is passed through the second conductive strip. The temperature fluctuation information on the two conductive strips is obtained by measuring the tripled frequency voltage signal on the first conductive line and the doubled frequency voltage signal on the second conductive line, and then the thermophysical properties of the film to be measured are inverted according to a certain heat transfer model. A key to implementing this method is how to eliminate the interference of the single frequency (base frequency) on the first conductive strip and the DC voltage signal on the second conductive line and accurately measure the weak tripled frequency voltage signal and doubled frequency voltage signal.

In the measurement of the in-plane thermal conductivity of the film, in order to obtain the thermophysical properties of the film, it is necessary not only to measure the triple frequency voltage signal and the double frequency voltage signal, but also to measure the resistance of the variable resistor and the two conductive strips in the circuit; if the AC current source that provides the heating current is not a constant current source, the amplitude of the AC current needs to be calibrated separately. In order to complete the measurement of the above physical quantities, it is necessary to frequently change the connection method of the measurement circuit, which is time-consuming. Therefore, in the process of measuring the in-plane thermophysical properties of the film, it is crucial to improve the accuracy of the measurement results and the efficiency of the measurement.

Utility Model Content

The utility model provides a device for measuring thermal physical quantities within a film surface, so as to solve the problems of low efficiency and low accuracy in the process of measuring thermal physical quantities within a film surface in the prior art.

According to one aspect of the utility model, a device for measuring thermal physical quantities in a film surface is provided, which is applied to the measurement of thermal conductivity, thermal diffusivity and volume heat capacity in a self-supporting film surface. The device for measuring thermal physical quantities in a film surface comprises:

A triple frequency signal acquisition box, a double frequency signal acquisition box, a data acquisition module and a control module;

The triple frequency signal acquisition box includes an AC current source module, a baseband signal elimination circuit, a first secondary amplifier, a first matrix switch and a sampling resistor; the triple frequency signal acquisition box is used to collect triple frequency signals;

The AC current source module is connected to the first conductive strip, the first conductive strip is connected to the baseband signal elimination circuit, the baseband signal elimination circuit is connected to the first secondary amplifier, the first secondary amplifier is connected to the first matrix switch, the first matrix switch is connected to the data acquisition module; the sampling resistor is connected to the first conductive strip and the first matrix switch respectively;

The double frequency signal acquisition box includes a DC/AC constant current source module, a DC signal elimination circuit, a second secondary amplifier and a second matrix switch; the double frequency signal acquisition box is used to collect double frequency signals;

The DC/AC constant current source module is connected to the second conductive strip, the second conductive strip is connected to the DC signal elimination circuit, the DC signal elimination circuit is connected to the second secondary amplifier, the second secondary amplifier is connected to the second matrix switch, and the second matrix switch is connected to the data acquisition module;

The AC current source module, the baseband signal elimination circuit and the first matrix switch are all connected to the control module in communication; the DC/AC constant current source module, the DC signal elimination circuit and the second matrix switch are all connected to the control module in communication;

The control module is connected to the data acquisition module and is used to calculate the thermal physical quantity in the film surface according to the triple frequency signal and the double frequency signal.

Optionally, the baseband signal elimination circuit includes: a first variable resistor, a first digital-to-analog conversion chip, a first digital output circuit, a first amplifier and a second amplifier, wherein the first amplifier and the second amplifier have the same amplification factor; a first conductive strip and a first variable resistor are connected in series; an input end of the first amplifier is respectively connected to two ends of the first conductive strip; an input end of the second amplifier is respectively connected to two ends of the first variable resistor; an output end of the second amplifier is connected to the first digital-to-analog conversion chip; and the first digital output circuit is connected to the first digital-to-analog conversion chip;

The first differential input terminal of the first secondary amplifier is connected to the output terminal of the first amplifier and the first input terminal of the first matrix switch respectively; the second differential input terminal of the first secondary amplifier is connected to the first digital-to-analog conversion chip and the third input terminal of the first matrix switch respectively; the output terminal of the first secondary amplifier is connected to the second input terminal of the first matrix switch;

The triple frequency signal acquisition box also includes a sampling resistor amplifier; the input end of the sampling resistor amplifier is respectively connected to the two ends of the sampling resistor, and the output end of the sampling resistor amplifier is connected to the fourth input end of the first matrix switch;

The DC signal elimination circuit includes: a second variable resistor, a second digital-to-analog conversion chip, a second digital output circuit, a third amplifier and a fourth amplifier, wherein the third amplifier and the fourth amplifier have the same amplification factor; the second conductive strip and the second variable resistor are connected in series; the input end of the third amplifier is respectively connected to the two ends of the second conductive strip; the input end of the fourth amplifier is respectively connected to the two ends of the second variable resistor; the output end of the fourth amplifier is connected to the second digital-to-analog conversion chip; the second digital output circuit is connected to the second digital-to-analog conversion chip;

The first differential input terminal of the second secondary amplifier is respectively connected to the output terminal of the third amplifier and the first input terminal of the second matrix switch; the second differential input terminal of the second secondary amplifier is respectively connected to the second digital-to-analog conversion chip and the third input terminal of the second matrix switch; the output terminal of the second secondary amplifier is connected to the second input terminal of the second matrix switch.

Optionally, the data acquisition module includes a first input terminal, a second input terminal and a third input terminal;

The first input terminal is connected to the first output terminal of the first matrix switch; the second input terminal is connected to the second output terminal of the first matrix switch; and the third input terminal is connected to the output terminal of the second matrix switch.

Optionally, the data acquisition module includes a synchronous data acquisition card or a phase-locked amplifier circuit.

Optionally, the triple frequency signal acquisition box further includes a first interaction unit;

The first interactive unit includes a first knob, a first panel signal input port, and a first panel signal output port;

The first knob is connected to the first variable resistor and is used to adjust the value of the first variable resistor; the first panel signal input port is connected to the wiring terminal of the first conductive strip, and the first matrix switch is connected to the data acquisition module through the first panel signal output port;

The double frequency signal acquisition box also includes a second interaction unit;

The second interactive unit includes a second knob, a second panel signal input port, and a second panel signal output port;

The second knob is connected to the second variable resistor for adjusting the value of the second variable resistor; the second panel signal input port is connected to the connection terminal of the second conductive strip, and the second matrix switch is connected to the data acquisition module through the second panel signal output port.

The technical solution of the utility model realizes the simultaneous acquisition of the triple frequency voltage signal on the first conductive strip and the double frequency voltage signal on the second conductive strip by setting a triple frequency signal acquisition box, a double frequency signal acquisition box, a data acquisition module and a control module in the device for measuring the thermal physical quantity in the film surface, eliminates the interference of the base frequency voltage signal and the DC voltage signal, and can easily switch to the resistance measurement function, thereby realizing the efficient and accurate measurement of the thermal physical quantity in the film surface. At the same time, the triple frequency signal acquisition box also includes a sampling resistor, which can also realize the function of current calibration and providing reference signal output.

It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present utility model, nor are they intended to limit the scope of the present utility model. Other features of the present utility model will become easily understood through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a connection diagram of a triple frequency signal acquisition box provided according to an embodiment of the utility model;

FIG2 is a connection diagram of a double frequency signal acquisition box provided according to an embodiment of the utility model;

3 is a schematic diagram of the connection of a triple frequency signal and a double frequency signal acquisition box provided according to an embodiment of the utility model;

4 is a schematic structural diagram of a first interactive unit of a triple frequency signal acquisition box provided according to an embodiment of the present utility model;

5 is a schematic structural diagram of a second interactive unit of a double frequency signal acquisition box provided according to an embodiment of the utility model;

6 is a flow chart of a first method for measuring thermal physical quantities within a film surface provided according to an embodiment of the present utility model;

7 is a flow chart of a first method for obtaining the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor according to an embodiment of the present utility model;

8 is a flow chart of a first method for obtaining the resistance value of the second conductive strip and the resistance value of the second variable resistor provided according to an embodiment of the present utility model;

9 is a flow chart of a second method for obtaining the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor according to an embodiment of the present utility model;

FIG10 is a flow chart of a method for eliminating a baseband signal according to an embodiment of the present utility model;

FIG11 is a flow chart of a method for eliminating DC signals according to an embodiment of the present utility model;

12 is a flow chart of a method for obtaining a triple frequency signal amplitude, a triple frequency signal initial phase, and a double frequency signal initial phase according to an embodiment of the present utility model;

FIG13 is a schematic diagram of a system for measuring thermal physical quantities within a film surface according to an embodiment of the present utility model;

FIG14 is a trend diagram showing the variation of the amplitude of the triple frequency signal of the first conductive strip in a thin film with the frequency of the excitation current according to an embodiment of the present invention;

FIG15 is a trend diagram showing the phase of temperature fluctuation on a first conductive strip and a second conductive strip in a thin film according to an embodiment of the present invention as a function of the frequency of the excitation current;

FIG. 16 is a diagram of a thin film according to an embodiment of the present invention. Schematic diagram of measurement results as the temperature fluctuation amplitude ΔT ₁ of the first conductive strip changes;

FIG. 17 is a schematic diagram of measurement results of the variation of the angular frequency ω of the excitation current in a thin film with M(2ω)·N(2ω) according to an embodiment of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here.

Fig. 1 is a schematic diagram of the connection of a triple frequency signal acquisition box provided according to an embodiment of the utility model, Fig. 2 is a schematic diagram of the connection of a double frequency signal acquisition box provided according to an embodiment of the utility model, and Fig. 3 is a schematic diagram of the connection of a triple frequency signal and double frequency signal acquisition box provided according to an embodiment of the utility model. The device for measuring thermal physical quantities within the film surface is applied to the measurement of thermal conductivity within the surface of the self-supporting film, the measurement of thermal diffusivity within the surface, and the measurement of volumetric heat capacity. When measuring thermal physical quantities within the surface of the self-supporting film, a first conductive strip and a second conductive strip parallel to each other are made on the surface of the self-supporting film, the first conductive strip serves as a heater and a thermometer, and the second conductive strip serves as a thermometer. The thermal physical properties of the film to be measured are calculated by using the measuring device to obtain the temperature fluctuation information on the first conductive strip and the second conductive strip. As shown in combination with Fig. 1, Fig. 2 and Fig. 3, the measuring device includes:

A triple frequency signal acquisition box 7, a double frequency signal acquisition box 8, a data acquisition module 9 and a control module 55;

The triple frequency signal acquisition box 7 includes an AC current source module 10, a baseband signal elimination circuit 11, a first secondary amplifier 12, a first matrix switch 13 and a sampling resistor 14; the triple frequency signal acquisition box 7 is used to collect triple frequency signals;

The AC current source module 10 is connected to the first conductive strip 4, the first conductive strip 4 is connected to the baseband signal elimination circuit 11, the baseband signal elimination circuit 11 is connected to the first secondary amplifier 12, the first secondary amplifier 12 is connected to the first matrix switch 13, and the first matrix switch 13 is connected to the data acquisition module 9; the sampling resistor 14 is connected to the first conductive strip 4 and the first matrix switch 13 respectively;

The double frequency signal acquisition box 8 includes a DC/AC constant current source module 30, a DC signal elimination circuit 31, a second secondary amplifier 32 and a second matrix switch 33; the double frequency signal acquisition box 8 is used to collect double frequency signals;

The DC/AC constant current source module 30 is connected to the second conductive strip 5, the second conductive strip 5 is connected to the DC signal elimination circuit 31, the DC signal elimination circuit 31 is connected to the second secondary amplifier 32, the second secondary amplifier 32 is connected to the second matrix switch 33, and the second matrix switch 33 is connected to the data acquisition module 9;

The AC current source module 10, the baseband signal elimination circuit 11 and the first matrix switch 13 are all connected to the control module 55; the DC/AC constant current source module 30, the DC signal elimination circuit 31 and the second matrix switch 33 are all connected to the control module 55;

The control module 55 is connected to the data acquisition module 9 and is used to calculate the thermal physical quantity within the film surface according to the triple frequency signal and the double frequency signal.

Among them, the triple frequency signal acquisition box 7 is connected to the first conductive strip 4 for collecting the triple frequency signal on the first conductive strip 4, the triple frequency signal acquisition box 7 collects the triple frequency voltage signal on the first conductive strip 4 and eliminates the fundamental frequency voltage signal on the first conductive strip 4 to prevent the fundamental frequency voltage signal from interfering with the measurement of the triple frequency voltage signal, thereby affecting the accuracy of the measurement of thermal physical quantities within the film surface; the double frequency signal acquisition box 8 is connected to the second conductive strip 5 for collecting the double frequency signal on the second conductive strip 5, the double frequency signal acquisition box 8 collects the double frequency voltage signal on the second conductive strip 5 and eliminates the DC voltage signal on the second conductive strip 5 to prevent the DC voltage signal from interfering with the measurement of the double frequency voltage signal, thereby affecting the accuracy of the measurement of thermal physical quantities within the film surface.

Specifically, the connection relationship of the triple frequency signal acquisition box 7 is as follows: the AC current source module 10 is connected to the first conductive strip 4, the first conductive strip 4 is connected to the baseband signal elimination circuit 11, the baseband signal elimination circuit 11 is connected to the first secondary amplifier 12, the first secondary amplifier 12 is connected to the first matrix switch 13, and the first matrix switch 13 is connected to the data acquisition module 9; the sampling resistor 14 is connected to the first conductive strip 4 and the first matrix switch 13 respectively. The AC current source module 10 is used to output an AC current of a certain frequency and amplitude, and the current passes through the first conductive strip 4 and the sampling resistor 14 connected in series in sequence; the baseband signal elimination circuit 11 is used to eliminate the baseband voltage signal in the first AC signal; the first secondary amplifier 12 plays a role in differential amplification of the voltage signal, and in some embodiments, the amplification factor of the first secondary amplifier 12 is at least 100 times; the first matrix switch 13 is used to transmit the voltage signal to the data acquisition module 9; the sampling resistor 14 is used to calibrate the output current amplitude of the AC current source and the output reference voltage signal.

The connection relationship of the double frequency signal acquisition box 8 is as follows: the DC/AC constant current source module 30 is connected to the second conductive strip 5, the second conductive strip 5 is connected to the DC signal elimination circuit 31, the DC signal elimination circuit 31 is connected to the second secondary amplifier 32, the second secondary amplifier 32 is connected to the second matrix switch 33, and the second matrix switch 33 is connected to the data acquisition module 9. The DC/AC constant current source module 30 is used to output a DC constant current or an AC constant current to the second conductive strip 5; the DC signal elimination circuit 31 is used to eliminate the DC voltage signal in the second AC signal; the second secondary amplifier 32 plays a role in differential amplification of the voltage signal. In some embodiments, the amplification factor of the second secondary amplifier 32 is at least 100 times; the second matrix switch 33 is used to transmit the voltage signal to the data acquisition module 9.

In addition, the AC current source module 10, the baseband signal elimination circuit 11 and the first matrix switch 13 are all communicatively connected to the control module 55. The control module 55 can control the frequency and amplitude of the output current of the AC current source module 10, and control the switching of the first matrix switch 13 so that different voltage signals are input into the data acquisition module 9; the DC/AC constant current source module 30, the DC signal elimination circuit 31 and the second matrix switch 33 are all communicatively connected to the control module 55. The control module 55 can control the DC/AC constant current source module 30 to output DC constant current or AC constant current of different sizes, and control the switching of the second matrix switch 33 so that different voltage signals are input into the data acquisition module 9.

Furthermore, the control module 55 can be used to control the measurement process and record data. The control module 55 and the data acquisition module 9 are connected to calculate the thermal physical quantity in the film surface according to the triple frequency signal and the double frequency signal.

The technical solution of the utility model realizes the simultaneous acquisition of the triple frequency voltage signal on the first conductive strip and the double frequency voltage signal on the second conductive strip by setting a triple frequency signal acquisition box, a double frequency signal acquisition box, a data acquisition module and a control module in the device for measuring the thermal physical quantity in the film surface, eliminates the interference of the base frequency voltage signal and the DC voltage signal, and can easily switch to the resistance measurement function, thereby realizing the efficient and accurate measurement of the thermal physical quantity in the film surface. At the same time, the triple frequency signal acquisition box also includes a sampling resistor, which can also realize the function of current calibration and providing reference signal output.

Optionally, with continued reference to FIGS. 1 , 2 and 3 , the baseband signal elimination circuit 11 includes: a first variable resistor 16, a first digital-to-analog conversion chip 19, a first digital output circuit 20, a first amplifier 17 and a second amplifier 18, wherein the first amplifier 17 and the second amplifier 18 have the same amplification factor; an input end of the first amplifier 17 is respectively connected to two ends of the first conductive strip 4; an input end of the second amplifier 18 is respectively connected to two ends of the first variable resistor 16; an output end of the second amplifier 18 is connected to the first digital-to-analog conversion chip 19; and the first digital output circuit 20 is connected to the first digital-to-analog conversion chip 19;

The first differential input terminal of the first secondary amplifier 12 is connected to the output terminal of the first amplifier 17 and the first input terminal 21 of the first matrix switch 13 respectively; the second differential input terminal of the first secondary amplifier 12 is connected to the first digital-to-analog conversion chip 19 and the third input terminal 23 of the first matrix switch 13 respectively; the output terminal of the first secondary amplifier 12 is connected to the second input terminal 22 of the first matrix switch 13;

The DC signal elimination circuit 31 includes: a second variable resistor 34, a second digital-to-analog conversion chip 37, a second digital output circuit 38, a third amplifier 35 and a fourth amplifier 36; the third amplifier 35 and the fourth amplifier 36 have the same amplification factor; the second conductive strip 5 and the second variable resistor 34 are connected in series; the input end of the third amplifier 35 is respectively connected to the two ends of the second conductive strip 5; the input end of the fourth amplifier 36 is respectively connected to the two ends of the second variable resistor 34, and the output end of the fourth amplifier 36 is connected to the second digital-to-analog conversion chip 37; the second digital output circuit 38 is connected to the second digital-to-analog conversion chip 37;

The first differential input terminal of the second secondary amplifier 32 is respectively connected to the output terminal of the third amplifier 35 and the first input terminal 39 of the second matrix switch 33; the second differential input terminal of the second secondary amplifier 32 is respectively connected to the second digital-to-analog conversion chip 37 and the third input terminal 41 of the second matrix switch 33; the output terminal of the second secondary amplifier 32 is connected to the second input terminal 40 of the second matrix switch 33.

Among them, the first digital-to-analog conversion chip 19 and the first digital output circuit 20 in the baseband signal elimination circuit 11 are used to adjust the gain range of the voltage signal amplified by the first variable resistor 16. The first digital output circuit 20 is communicated with the control module 55. The control module 55 controls the gain of the first digital-to-analog conversion chip 19. The first digital output circuit 20 outputs the gain control signal to the first digital-to-analog conversion chip 19.

The principle of the baseband signal elimination circuit 11 is as follows: the first conductive strip 4 and the first variable resistor 16 are connected in series, and the two ends of the first conductive strip 4 are connected to the first amplifier 17. The first amplifier 17 is used to amplify the voltage signal at the two ends of the first conductive strip 4 and input the voltage signal at the two ends of the first conductive strip 4 to the first differential input end of the first secondary amplifier 12; the two ends of the first variable resistor 16 are connected to the second amplifier 18, and the second amplifier 18 is used to amplify the voltage signal of the first variable resistor 16 and input the voltage signal at the two ends of the first variable resistor 16 to the second differential input end of the first secondary amplifier 12, and the output end of the second amplifier 18 is connected to the first digital-to-analog conversion chip 19. The resistance value of the first variable resistor 16 is adjusted to be greater than the resistance value of the first conductive strip 4, and then the gain of the first digital-to-analog conversion chip 19 is adjusted and set so that the amplified baseband voltage signal of the second differential input terminal of the first variable resistor 16 input to the first secondary amplifier 12 is close to the amplified baseband voltage signal of the first conductive strip 4. When the amplified voltage signal of the first conductive strip 4 and the amplified voltage signal of the first variable resistor 16 are differentially input to the first secondary amplifier 12, the voltage signal output by the first secondary amplifier 12 eliminates the baseband voltage signal in the voltage signal of the first conductive strip, thereby eliminating the baseband voltage signal in the first conductive strip 4.

Among them, the second digital-to-analog conversion chip 37 and the second digital output circuit 38 in the DC signal elimination circuit 31 are used to adjust the gain range of the voltage signal of the second variable resistor 34. The second digital output circuit 38 is communicated with the control module 55. The control module 55 controls the gain of the second digital-to-analog conversion chip 37. The second digital output circuit 38 outputs the gain control signal to the second digital-to-analog conversion chip 37.

The principle of the DC signal elimination circuit 31 is as follows: the second conductive strip 5 is connected in series with the second variable resistor 34, and the two ends of the second conductive strip 5 are connected to the third amplifier 35, and the third amplifier 35 is used to amplify the voltage signal at the two ends of the second conductive strip 5 and input the voltage signal at the two ends of the second conductive strip 5 into the first differential input end of the second secondary amplifier 32; the two ends of the second variable resistor 34 are connected to the fourth amplifier 36, and the fourth amplifier 36 is used to amplify the voltage signal of the second variable resistor 34 and input the voltage signal at the two ends of the second variable resistor 34 into the second differential input end of the second secondary amplifier 32. The resistance value of the second variable resistor 34 is adjusted to be greater than the resistance value of the second conductive strip 5, and then the gain of the second digital-to-analog conversion chip 37 is set so that the amplified DC voltage signal of the second variable resistor 34 input to the second differential input end of the second secondary amplifier 32 is close to the amplified DC voltage signal of the second conductive strip 5. When the amplified voltage signal of the second conductive strip 5 and the amplified voltage signal of the second variable resistor 34 are differentially input into the second secondary amplifier 32, the voltage signal output by the second secondary amplifier 32 eliminates the DC voltage signal in the voltage signal of the second conductive strip, thereby eliminating the DC voltage signal in the second conductive strip 5.

It can be understood that the amplification factor of the first amplifier 17 and the amplification factor of the second amplifier 18 in the embodiment of the utility model are the same, the purpose is to synchronously amplify the voltage signal at both ends of the first conductive strip 4 and the voltage signal at both ends of the first variable resistor 16, so as to more accurately eliminate the baseband voltage signal. At the same time, the triple frequency signal output by the first secondary amplifier 12 is amplified in two stages, which improves the accuracy of the triple frequency signal output. The amplification factor of the third amplifier 35 is the same as the amplification factor of the fourth amplifier 36, the purpose is to synchronously amplify the voltage signal at both ends of the second conductive strip 5 and the voltage signal at both ends of the second variable resistor 34, so as to more accurately eliminate the DC voltage signal. At the same time, the double frequency signal output by the second secondary amplifier 32 is amplified in two stages, which improves the accuracy of the double frequency signal output.

The technical solution of the embodiment of the utility model discloses the connection relationship between the baseband signal elimination circuit and the DC signal elimination circuit, clarifies the elimination principle of the baseband voltage signal and the DC voltage signal, and realizes the accurate measurement of thermal physical quantities within the film surface.

Optionally, referring to FIG. 1 , FIG. 2 and FIG. 3 , the data acquisition module 9 includes a first input terminal 27 , a second input terminal 28 and a third input terminal 29 ;

The first input terminal 27 is connected to the first output terminal of the first matrix switch 13 ; the second input terminal 28 is connected to the second output terminal of the first matrix switch 13 ; and the third input terminal 29 is connected to the output terminal of the second matrix switch 33 .

Among them, the first input terminal 27 and the second input terminal 28 are used to input the voltage signal in the triple frequency signal acquisition box 7 into the data acquisition module 9 respectively; the third input terminal 29 is used to input the voltage signal in the double frequency signal acquisition box 8 into the data acquisition module 9.

It can be understood that different voltage signals can be input into the data acquisition module 9 by switching the first matrix switch 13, and different voltage signals can be input into the data acquisition module 9 by switching the second matrix switch 33. The technical solution of the embodiment of the utility model, by setting multiple input terminals in the data acquisition module, enables the triple frequency signal acquisition box and the double frequency signal acquisition box to work simultaneously and input the voltage signals into the data acquisition module simultaneously, thereby improving the efficiency of measuring the thermal physical quantity in the film surface.

Optionally, with continued reference to FIG. 1 , FIG. 2 and FIG. 3 , the data acquisition module 9 includes a synchronous data acquisition card or a phase-locked amplifier circuit.

Specifically, taking the synchronous data acquisition card as an example, the synchronous data acquisition card includes a first input terminal, a second input terminal and a third input terminal. The first input terminal is connected to the second input terminal 22 of the first matrix switch 13, so that the triple frequency signal is output to the synchronous data acquisition card; the second input terminal is connected to the fourth input terminal 24 of the first matrix switch 13, so that the reference signal of the sampling resistor 14 is output to the synchronous data acquisition card; the third input terminal is connected to the second input terminal 40 of the second matrix switch 33, so that the double frequency signal is output to the synchronous data acquisition card.

Specifically, taking the phase-locked amplifier circuit as an example: the phase-locked amplifier circuit includes a first sub-phase-locked amplifier circuit and a second sub-phase-locked amplifier circuit, the first sub-phase-locked amplifier circuit includes a first signal input terminal, the second sub-phase-locked amplifier circuit includes a third signal input terminal, and the second input terminal is shared by the first sub-phase-locked amplifier circuit and the second sub-phase-locked amplifier circuit as a reference signal input terminal. The first input terminal is connected to the second input terminal 22 of the first matrix switch 13, so that the triple frequency signal is output to the first sub-phase-locked amplifier circuit, the second input terminal is connected to the fourth input terminal 24 of the first matrix switch 13, so that the baseband reference signal of the sampling resistor 14 is output to the first sub-phase-locked amplifier circuit and the second sub-phase-locked amplifier circuit; the third input terminal is connected to the second input terminal 40 of the second matrix switch 33, so that the double frequency signal is output to the second sub-phase-locked amplifier circuit.

The technical solution of the embodiment of the utility model is to set a synchronous data acquisition card or a phase-locked amplifier circuit in the data acquisition module, so that the first AC signal acquisition box and the second AC signal acquisition box can work simultaneously and input the voltage signal into the data acquisition module at the same time, thereby improving the efficiency of measuring thermal physical quantities within the film surface.

Optionally, FIG4 is a schematic diagram of the structure of a first interactive unit of a triple frequency signal acquisition box provided according to an embodiment of the present utility model, and FIG5 is a schematic diagram of the structure of a second interactive unit of a double frequency signal acquisition box provided according to an embodiment of the present utility model, in combination with FIG1, FIG2, FIG3, FIG4 and FIG5:

The triple frequency signal acquisition box 7 also includes a first interaction unit;

The first interactive unit includes a first knob 61, a first panel signal input port 62 and a first panel signal output port 63;

The first knob 61 is connected to the first variable resistor 16 and is used to adjust the value of the first variable resistor 16; the first panel signal input port 62 is connected to the wiring terminal of the first conductive strip 4, and the first matrix switch 13 is connected to the data acquisition module 9 through the first panel signal output port 63;

The double frequency signal acquisition box 8 also includes a second interaction unit;

The second interactive unit includes a second knob 61, a second panel signal input port 62, and a second panel signal output port 63;

The second knob 61 is connected to the second variable resistor 34 for adjusting the size of the second variable resistor 34 ; the second panel signal input port 62 is connected to the connection terminal of the second conductive strip 5 , and the second matrix switch 33 is connected to the data acquisition module 9 via the second panel signal output port 63 .

Among them, the first interactive unit can be a panel of the triple frequency signal acquisition box 7, the first knob 61 is used to adjust the size of the first variable resistor 16, the first panel signal input port 62 is connected to the terminal of the first conductive strip 4, and the first panel signal output port 63 is connected to the data acquisition module 9 to realize the input of the voltage signal of the first conductive strip 4 and the output of the triple frequency signal and other voltage signals.

The second interactive unit can be a panel of the double frequency signal acquisition box 8, the second knob 61 is used to adjust the size of the second variable resistor 34, the second panel signal input port 62 is connected to the terminal of the second conductive strip 5, and the second panel signal output port 63 is connected to the data acquisition module 9 to realize the input of the voltage signal of the second conductive strip 5 and the output of the double frequency signal and other voltage signals.

The technical solution of the embodiment of the utility model, by setting up a first interactive unit and a second interactive unit, allows the operator to conveniently realize the collection of triple frequency signals, double frequency signals and other voltage signals through the interaction between the first interactive unit and the second interactive unit, thereby ensuring the measurement efficiency of thermal physical quantities within the film surface.

Based on the same utility model concept, the embodiment of the utility model further provides a method for measuring thermal physical quantities in a film plane, which is applied to a device for measuring thermal physical quantities in a film plane. FIG6 is a flow chart of a first method for measuring thermal physical quantities in a film plane provided according to an embodiment of the utility model, wherein the first AC signal includes the triple frequency signal and the base frequency signal; the second AC signal includes the double frequency signal and the DC signal. As shown in FIG6 and FIG3, the method for measuring thermal physical quantities in a film plane includes:

S11, obtaining the resistance temperature coefficient of the first conductive strip, the current amplitude of the AC current source module, the resistance value of the first conductive strip, the resistance value of the first variable resistor, the resistance value of the second conductive strip, the resistance value of the second variable resistor, the film thickness, and the spacing between the first conductive strip and the second conductive strip.

The self-supporting film surface in the embodiment of the utility model includes a parallel first conductive strip 4 and a second conductive strip 5, wherein the first conductive strip 4 serves as a heater and a thermometer, and the second conductive strip 5 serves only as a thermometer, thereby realizing the measurement of thermal physical quantities.

Among them, the current amplitude of the triple frequency current source module 10, the resistance value of the first conductive strip 4 and the resistance value of the first variable resistor 16 can be obtained through the triple frequency signal acquisition box 7. Further, the resistance temperature coefficient of the first conductive strip 4 can be calculated according to the resistance value of the first conductive strip 4 that changes with temperature; the double frequency signal acquisition box 8 can obtain the resistance value of the second conductive strip 5 and the resistance value of the second variable resistor 34.

Among them, in order to calculate the in-plane thermal conductivity and in-plane thermal diffusivity of the film, it is also necessary to know the film thickness and the distance between the first conductive strip 4 and the second conductive strip 5. Therefore, the film thickness and the distance between the first conductive strip 4 and the second conductive strip 5 are also necessary conditions for calculating the in-plane thermal physical quantities of the film.

S12. Adjust the baseband signal elimination circuit according to the resistance value of the first conductive strip and the resistance value of the first variable resistor to eliminate the baseband signal in the first AC signal; adjust the DC signal elimination circuit according to the resistance value of the second conductive strip and the resistance value of the second variable resistor to eliminate the DC signal in the second AC signal.

Among them, based on the baseband signal elimination circuit and the first secondary amplifier 12, the first AC signal is input to the first input end of the first secondary amplifier 12, and the baseband signal is input to the second input end of the first secondary amplifier 12. By using the differential input working principle of the first secondary amplifier 12, the output end of the first secondary amplifier 12 mainly outputs the amplified triple frequency signal to eliminate the baseband signal in the first AC signal. Similarly, based on the DC signal elimination circuit and the second secondary amplifier 32, the second AC signal is input to the first input end of the second secondary amplifier 32, and the DC signal is input to the second input end of the second secondary amplifier 32, so that the output end of the second secondary amplifier 32 mainly outputs the amplified double frequency signal to eliminate the DC signal in the second AC signal.

S13, determining the amplitude of the tripled frequency signal and the initial phase of the tripled frequency signal according to the tripled frequency signal; and determining the initial phase of the doubled frequency signal according to the doubled frequency signal.

The purpose of obtaining the initial phase of the triple frequency signal and the initial phase of the double frequency signal based on the excitation current signal is to obtain the temperature fluctuation phase of the first conductive strip 4 and the second conductive strip 5 according to the initial phase.

It can be understood that according to the currents of different frequencies and magnitudes, different triple frequency signal amplitudes, triple frequency signal initial phases and double frequency signal initial phases can be obtained, and then the in-plane thermal conductivity, in-plane thermal diffusivity and volume heat capacity of the film at this temperature can be calculated.

S14. Determine the film's in-plane thermal conductivity, film's in-plane thermal diffusivity and film's volumetric heat capacity based on the resistance temperature coefficient of the first conductive strip, the current amplitude of the AC current source module, the resistance value of the first conductive strip, the tripled frequency signal amplitude, the tripled frequency signal initial phase, the doubled frequency signal initial phase, the film thickness and the spacing between the first conductive strip and the second conductive strip.

Specifically, according to the initial phase Φ _3ω of the triple frequency signal and the initial phase Φ _2ω of the double frequency signal, the phases Φ(2ω) ₁ and Φ(2ω) ₂ of the temperature fluctuation on the first conductive strip 4 and the second conductive strip 5 can be further obtained, wherein Φ(2ω) ₁ =Φ _3ω +π/2, Φ(2ω) ₂ =Φ _2ω . It can be understood that when currents with the same amplitude but different angular frequencies are input into the triple frequency signal acquisition box, the triple frequency signal amplitude corresponding to the currents with different angular frequencies, the phase Φ(2ω) ₁ of the temperature fluctuation on the first conductive strip 4 and the phase Φ(2ω) ₂ of the temperature fluctuation on the second conductive strip 5 can be obtained, and the in-plane thermal conductivity, in-plane thermal diffusivity and volume heat capacity of the sample at the temperature can be calculated accordingly.

The technical solution of the embodiment of the utility model realizes the simultaneous acquisition of the triple frequency voltage signal on the first conductive strip and the double frequency voltage signal on the second conductive strip by setting a triple frequency signal acquisition box, a double frequency signal acquisition box, a data acquisition module and a control module in the device for measuring the thermal physical quantity in the film surface, eliminates the interference of the base frequency voltage signal and the DC voltage signal, and can easily switch to the resistance measurement function, thereby realizing the efficient and accurate measurement of the thermal physical quantity in the film surface. At the same time, the triple frequency signal acquisition box also includes a sampling resistor, which can also realize the function of current calibration and providing reference signal output.

Optionally, based on the above embodiments, with continued reference to FIG. 1 , FIG. 2 and FIG. 3 , the baseband signal elimination circuit 11 includes: a first variable resistor 16, a first digital-to-analog conversion chip 19, a first digital output circuit 20, a first amplifier 17 and a second amplifier 18, wherein the amplification factors of the first amplifier 17 and the second amplifier 18 are the same; the first conductive strip 4 and the first variable resistor 16 are connected in series; the input end of the first amplifier 17 is respectively connected to the two ends of the first conductive strip 4; the input end of the second amplifier 18 is respectively connected to the two ends of the first variable resistor 16; the output end of the second amplifier 18 is connected to the first digital-to-analog conversion chip 19; the first digital output circuit 20 is connected to the first digital-to-analog conversion chip 19;

The first differential input terminal of the first secondary amplifier 12 is connected to the output terminal of the first amplifier 17 and the first input terminal 21 of the first matrix switch 13 respectively; the second differential input terminal of the first secondary amplifier 12 is connected to the first digital-to-analog conversion chip 19 and the third input terminal 23 of the first matrix switch 13 respectively; the output terminal of the first secondary amplifier 12 is connected to the second input terminal 22 of the first matrix switch 13;

The DC signal elimination circuit 31 includes: a second variable resistor 34, a second digital-to-analog conversion chip 37, a second digital output circuit 38, a third amplifier 35 and a fourth amplifier 36; the third amplifier 35 and the fourth amplifier 36 have the same amplification factor; the second conductive strip 5 and the second variable resistor 34 are connected in series; the input end of the third amplifier 35 is respectively connected to the two ends of the second conductive strip 5; the input end of the fourth amplifier 36 is respectively connected to the two ends of the second variable resistor 34, and the output end of the fourth amplifier 36 is connected to the second digital-to-analog conversion chip 37; the second digital output circuit 38 is connected to the second digital-to-analog conversion chip 37;

The first differential input terminal of the second secondary amplifier 32 is respectively connected to the output terminal of the third amplifier 35 and the first input terminal 39 of the second matrix switch 33; the second differential input terminal of the second secondary amplifier 32 is respectively connected to the second digital-to-analog conversion chip 37 and the third input terminal 41 of the second matrix switch 33; the output terminal of the second secondary amplifier 32 is connected to the second input terminal 40 of the second matrix switch 33.

When the data acquisition module 9 includes a synchronous data acquisition card, the method for obtaining the current amplitude of the AC current source module, the resistance value of the first conductive strip, the resistance value of the first variable resistor, the resistance value of the second conductive strip and the resistance value of the second variable resistor is as follows:

FIG7 is a flow chart of a first method for obtaining the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor according to an embodiment of the present utility model, as shown in FIG7 :

S20 , outputting a first control signal to the AC current source module to control the AC current source module to output AC current.

The first control signal is used to control the AC current source module 10 to output a current with an angular frequency of ω and transmit the current to the first conductive strip 4 , the first variable resistor 16 and the sampling resistor 14 .

S21 , outputting a second control signal to the first digital output circuit to control the gain of the first digital-to-analog conversion chip to 1.

The second control signal is output to the first digital output circuit 20 to control the gain of the first digital-to-analog conversion chip 19 to be 1, that is, the voltage signal of the first variable resistor 16 does not attenuate, and the resistance value of the first variable resistor 16 calculated accordingly is the real resistance value.

S22, outputting a third control signal to the first matrix switch to control the first matrix switch to sequentially output the first conductive strip voltage signal, the first variable resistor voltage signal and the sampling resistor voltage signal to the synchronous data acquisition card.

Among them, the third control signal is used to control the switching of the first matrix switch 13, and sequentially controls the first input terminal 21, the third input terminal 23 and the fourth input terminal 24 of the first matrix switch 13 to output the first conductive strip voltage signal, the first variable resistor voltage signal and the sampling resistor voltage signal to the data acquisition module 9.

S23, performing a fast Fourier transform on the first conductive strip voltage signal to obtain the amplitude of the baseband signal of the first conductive strip, performing a fast Fourier transform on the first variable resistor voltage signal to obtain the amplitude of the baseband signal of the first variable resistor, and performing a fast Fourier transform on the sampling resistor voltage signal to obtain the amplitude of the baseband signal of the sampling resistor.

Among them, the data acquisition module 9 collects the time domain signal of the first conductive strip voltage signal, the time domain signal of the first variable resistor voltage signal and the time domain signal of the sampling resistor voltage signal, and performs fast Fourier transform on the above signals to obtain the fundamental frequency signal amplitude of the first conductive strip 4, the fundamental frequency signal amplitude of the first variable resistor 16 and the fundamental frequency signal amplitude of the sampling resistor 14.

S24, calculating the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor according to the resistance value of the sampling resistor, the fundamental frequency signal amplitude of the first conductive strip, the fundamental frequency signal amplitude of the first variable resistor, and the fundamental frequency signal amplitude of the sampling resistor.

Among them, since the resistance value of the sampling resistor 14 is a known quantity, the current amplitude of the AC current source module 10, the resistance value of the first conductive strip 4, and the resistance value of the first variable resistor 16 can be calculated according to the fundamental frequency signal amplitude of the first conductive strip 4, the fundamental frequency signal amplitude of the first variable resistor 16, and the fundamental frequency signal amplitude of the sampling resistor 14.

FIG8 is a flow chart of a first method for obtaining the resistance value of the second conductive strip and the resistance value of the second variable resistor according to an embodiment of the present utility model, as shown in FIG8 :

S30, outputting a fourth control signal to the DC/AC constant current source module to control the DC/AC constant current source module to output a plurality of DC currents of different magnitudes.

S31 , outputting a fifth control signal to the second digital output circuit to control the gain of the second digital-to-analog conversion chip to be 1.

Among them, the fourth control signal is used to control the DC/AC constant current source module 30 to output multiple DC currents of different sizes and transmit the DC current to the second conductive strip 5 and the second variable resistor 34, so that the voltage of the second conductive strip 5 and the voltage of the second variable resistor 34 under multiple DC currents of different sizes can be obtained; the fifth control signal is output to the second digital output circuit 38, and the gain of the second digital-to-analog conversion chip 37 is controlled to be 1, that is, the voltage signal of the second variable resistor 34 does not attenuate, that is, the voltage value of the second variable resistor 34 at this time is a real value that does not attenuate.

S32, outputting a sixth control signal to the second matrix switch to control the second matrix switch to sequentially output a plurality of second conductive strip voltage signals and a plurality of second variable resistor voltage signals to the synchronous data acquisition card.

Among them, the switching of the second matrix switch 33 indicates switching between different circuits, and controls the first input terminal 39 and the third input terminal 41 of the second matrix switch 33 to be connected with the synchronous data acquisition card in turn, so as to output multiple second conductive strip voltage signals and multiple second variable resistor voltage signals to the data acquisition module 9 for subsequent analysis and processing of the data.

S33. Determine a linear fitting curve of the second conductive strip according to a plurality of currents of different magnitudes and a plurality of second conductive strip voltage signals, and determine a resistance value of the second conductive strip according to the linear fitting curve.

S34, determining a linear fitting curve of the second variable resistor according to a plurality of currents of different magnitudes and a plurality of second variable resistor voltage signals, and determining a resistance value of the second variable resistor according to the linear fitting curve.

Among them, the second conductive strip voltage signal is linearly fitted to the current, and the slope after linear fitting is the resistance value of the second conductive strip 5; the second variable resistor voltage signal is linearly fitted to the current, and the slope after linear fitting is the resistance value of the second variable resistor 34.

When the data acquisition module includes a phase-locked amplifier circuit, the method for obtaining the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor is as follows:

FIG9 is a flow chart of a second method for obtaining the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor according to an embodiment of the present utility model, as shown in FIG9 :

S40 , outputting a seventh control signal to the AC current source module to control the AC current source module to output AC current.

S41 , outputting an eighth control signal to the first digital output circuit to control the gain of the first digital-to-analog conversion chip to be 1.

S42, outputting a ninth control signal to the first matrix switch to control the first matrix switch to sequentially output the first conductive strip voltage signal, the first variable resistor voltage signal and the sampling resistor voltage signal to the phase-locked amplifier circuit.

S43, using a phase-locked amplifier circuit to process the first conductive strip voltage signal to determine the amplitude of the fundamental frequency signal of the first conductive strip, process the first variable resistor voltage signal to determine the amplitude of the fundamental frequency signal of the first variable resistor, and process the sampling resistor voltage signal to obtain the amplitude of the fundamental frequency signal of the sampling resistor.

Among them, since the data acquisition module 9 is a phase-locked amplifier circuit, there is no need to obtain the signal amplitude through Fourier transform. The phase-locked technology can directly obtain the fundamental frequency signal amplitude of the first conductive strip 4, the fundamental frequency signal amplitude of the first variable resistor 16 and the fundamental frequency signal amplitude of the sampling resistor 14.

S44, calculating the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor according to the resistance value of the sampling resistor, the fundamental frequency signal amplitude of the first conductive strip, the fundamental frequency signal amplitude of the first variable resistor, and the fundamental frequency signal amplitude of the sampling resistor.

Similarly, when a phase-locked amplifier circuit is provided in the data acquisition module 9, the DC/AC constant current source 30 can be controlled to output a constant AC current to the second conductive strip 5 and the second variable resistor 34, and the gain of the second digital-to-analog conversion chip 37 can be controlled to be 1. The second matrix switch is controlled to sequentially output the second conductive strip voltage signal and the second variable resistor voltage signal to the phase-locked amplifier circuit. The phase-locked amplifier circuit is used to process the second conductive strip voltage signal to determine the amplitude of the baseband signal of the second conductive strip and calculate the resistance value of the second conductive strip, and the second variable resistor voltage signal is processed to determine the amplitude of the baseband signal of the second variable resistor and calculate the resistance value of the second variable resistor.

The technical solution of the embodiment of the utility model can directly measure the resistance value of the first conductive strip, the resistance value of the second conductive strip, the resistance value of the first variable resistor and the resistance value of the second variable resistor by adopting a synchronous data acquisition card method or a phase-locked amplifier circuit method in conjunction with a triple frequency signal acquisition box and a double frequency signal acquisition box, so that the triple frequency signal acquisition box and the double frequency signal acquisition box have the function of measuring triple frequency signals and double frequency signals as well as the function of resistance measurement.

In some embodiments, FIG10 is a flow chart of a method for eliminating a baseband signal according to an embodiment of the present utility model. As shown in FIG10 and FIG3 , the method includes:

S50, adjusting the resistance value R _br of the first variable resistor to be greater than the resistance value R _Q1 of the first conductive strip, and determining a first attenuation ratio R _Q1 /R _br according to the resistance value R _br of the first variable resistor and the resistance value R _Q1 of the first conductive strip.

Among them, the principle of eliminating the baseband signal is to offset the baseband signal in the first conductive strip voltage signal, so the attenuation ratio needs to be determined according to the first variable resistor resistance value R _br and the first conductive strip resistance value R _Q1 , so that the amplitude of the attenuated first variable resistor baseband voltage signal is the same as the amplitude of the baseband component in the first conductive strip voltage signal.

S51. Output a tenth control signal to the first digital output circuit according to the first attenuation ratio R _Q1 /R _br to adjust the gain of the first digital-to-analog conversion chip so that the amplitude of the fundamental frequency component of the voltage signal of the attenuated first variable resistor is the same as the amplitude of the fundamental frequency component of the first AC signal, so as to differentially eliminate the fundamental frequency signal in the first AC signal when inputting the first secondary amplifier.

When the attenuated amplified voltage signal of the first variable resistor 16 and the amplified voltage signal of the first conductive strip 4 are differentially input to the first secondary amplifier 12 , the fundamental frequency voltage signal of the first variable resistor 16 and the fundamental frequency voltage signal of the first conductive strip 4 are offset to the greatest extent.

FIG11 is a flow chart of a method for eliminating a DC signal according to an embodiment of the present utility model. In combination with FIG11 and FIG3 , the method includes:

S60, adjusting the resistance value R _ar of the second variable resistor to be greater than the resistance value R _Q2 of the second conductive strip, and determining a second attenuation ratio R _Q2 /R _ar according to the resistance value R _ar of the second variable resistor and the resistance value R _Q2 of the second conductive strip.

Among them, the principle of eliminating the DC signal is to offset the DC signal in the second conductive strip voltage signal, so the attenuation ratio needs to be determined according to the second variable resistor resistance value R _ar and the second conductive strip resistance value R _Q2 , so that the amplitude of the attenuated second variable resistor DC voltage signal is the same as the amplitude of the DC component in the second conductive strip voltage signal.

S61. Control the second digital output circuit according to the second attenuation ratio R _Q2 /R _ar to adjust the gain of the second digital-to-analog conversion chip so that the DC component of the attenuated voltage signal of the second variable resistor is the same as the DC component of the second AC signal, so as to differentially eliminate the DC signal in the second AC signal when inputting the second secondary amplifier.

Among them, when the attenuated amplified voltage signal of the second variable resistor 34 and the amplified voltage signal of the second conductive strip 5 are differentially input to the second secondary amplifier 32, the DC voltage signal of the second variable resistor 34 and the DC voltage signal component of the second conductive strip 5 will be offset to the greatest extent, thereby preventing the output signal of the second secondary amplifier 32 from exceeding the measuring range of the data acquisition module 9.

The technical solution of the embodiment of the utility model adjusts the first variable resistor and the second variable resistor, and adjusts the gain of the first digital-to-analog conversion chip and the gain of the second digital-to-analog conversion chip, so that the baseband signal in the first AC signal passing through the first secondary amplifier is offset, and the DC signal in the second AC signal passing through the second secondary amplifier is offset, so as to obtain accurate tripled frequency signal and doubled frequency signal, thereby improving the accuracy of the device for measuring thermal physical quantities within the thin film surface.

In some embodiments, FIG12 is a flow chart of a method for obtaining the amplitude of a triple frequency signal, an initial phase of a triple frequency signal, and an initial phase of a double frequency signal according to an embodiment of the present invention. As shown in FIG12 , the method includes:

S70, controlling the input end of the synchronous data acquisition card to be connected to the second input end of the first matrix switch, the fourth input end of the first matrix switch, and the second input end of the second matrix switch respectively.

Among them, the first input terminal 27 of the synchronous data acquisition card is controlled to be connected with the second input terminal 22 of the first matrix switch 13, so that the triple frequency signal amplified by the first secondary amplifier 12 is continuously input into the synchronous data acquisition card; the third input terminal 29 of the synchronous data acquisition card is controlled to be connected with the second input terminal 40 of the second matrix switch 33, so that the double frequency signal amplified by the second secondary amplifier 32 is continuously input into the synchronous data acquisition card; the second input terminal 28 of the synchronous data acquisition card is controlled to be connected with the fourth input terminal 24 of the first matrix switch 13, so that the baseband voltage signal of the sampling resistor 14 can be continuously input into the synchronous data acquisition card as a reference signal.

It is understandable that in order to ensure phase consistency, the sampling resistor base frequency signal and the triple frequency signal must be collected synchronously, and the sampling resistor base frequency signal and the double frequency signal must also be collected synchronously. In order to improve measurement efficiency, the sampling resistor base frequency signal, triple frequency signal and double frequency signal can be collected synchronously.

S71, controlling the AC current source module to output a plurality of currents with different angular frequencies and controlling the DC/AC constant current source module to output a constant DC current.

Among them, since in the measuring device provided by the embodiment of the utility model, the first conductive strip 4 is used as a heater and a thermometer, and the second conductive strip 5 is used as a thermometer, a plurality of currents with constant amplitudes and different angular frequencies are outputted only to the first conductive strip 4 to generate temperature fluctuations, and the temperature fluctuation information of the first conductive strip 4 can be obtained by measuring the tripled frequency voltage signal drawn from the first conductive strip 4; a constant direct current is outputted to the second conductive strip 5, and the temperature fluctuation information of the second conductive strip 5 can be obtained by measuring the doubled frequency voltage signal drawn from the second conductive strip 5.

S72, controlling the data acquisition module to synchronously receive a plurality of first secondary amplifier voltage signals, a plurality of sampling resistor voltage signals, and a plurality of corresponding second secondary amplifier voltage signals.

S73, determine the amplitudes of multiple tripled frequency signals and the real-time phases of multiple tripled frequency signals by fast Fourier transform of multiple first secondary amplifier voltage signals; determine the real-time phases of multiple sampling resistor baseband voltage signals by fast Fourier transform of multiple sampling resistor voltage signals; determine the amplitudes of multiple doubled frequency signals and the real-time phases of multiple doubled frequency signals by fast Fourier transform of multiple second secondary amplifier voltage signals.

Among them, the first secondary amplifier voltage signal is data processed to obtain the amplitude of the tripled frequency signal and the real-time phase of the tripled frequency signal corresponding to different angular frequencies; the multiple sampling resistor voltage signals are data processed to obtain the real-time phase of the sampling resistor baseband voltage signal corresponding to different angular frequencies; the second stage amplifier voltage signal is data processed to obtain the amplitude of the doubled frequency signal and the real-time phase of the doubled frequency signal corresponding to different angular frequencies.

S74, determining multiple initial phases of tripled frequency signals according to the real-time phases of multiple tripled frequency signals and the corresponding real-time phases of multiple sampling resistor fundamental frequency voltage signals; determining multiple initial phases of doubled frequency signals according to the real-time phases of multiple doubled frequency signals and the corresponding real-time phases of multiple sampling resistor fundamental frequency voltage signals.

In some embodiments, the initial phase Φ _3ω of the triple frequency signal, the real-time phase Φ _Ref of the sampling resistor base frequency signal and the real-time phase Φ _3ω,A of the triple frequency signal satisfy Φ _3ω ＝Φ _3ω,A -mod(f _3ω ×T ₀ ×360,360), wherein T ₀ ＝Φ _Ref /(360×f _1ω ), f _1ω ＝ω/(2π), f _3ω ＝3ω/(2π); the sampling resistor base frequency signal and the triple frequency signal are collected synchronously;

The initial phase Φ _2ω of the double frequency signal, the real-time phase Φ _Ref of the sampling resistor base frequency signal and the real-time phase Φ _2ω,A of the double frequency signal satisfy Φ _2ω ＝Φ _2ω,A -mod(f _2ω ×T ₀ ×360,36)0, wherein T ₀ ＝Φ _Ref /(360×f _1ω ), f _1ω ＝ω/(2π), f _2ω ＝2ω/(2π); the base frequency signal of the sampling resistor and the double frequency signal are collected synchronously.

The technical solution of the embodiment of the utility model provides a method for measuring the initial phase of a triple frequency signal and the initial phase of a double frequency signal. By adopting this measurement method, when measuring weak AC signals, there is no need to use a phase-locked amplifier or to set up additional hardware such as a trigger circuit and a reference signal source, thereby achieving a compact layout of the overall structure of the instrument and greatly reducing the cost of the measuring device.

The technical solution of the utility model realizes the simultaneous acquisition of the triple frequency voltage signal on the first conductive strip and the double frequency voltage signal on the second conductive strip by setting a triple frequency signal acquisition box, a double frequency signal acquisition box, a data acquisition module and a control module in the device for measuring the thermal physical quantity in the film surface, eliminates the interference of the base frequency voltage signal and the DC voltage signal, and can easily switch to the resistance measurement function, thereby realizing the efficient and accurate measurement of the thermal physical quantity in the film surface. At the same time, the triple frequency signal acquisition box also includes a sampling resistor, which can also realize the function of current calibration and providing reference signal output.

Based on the same utility model concept, the utility model embodiment also provides a thin film surface thermal physical quantity measurement system. Figure 13 is a schematic diagram of a thin film surface thermal physical quantity measurement system provided according to the utility model embodiment. Combined with Figure 13 and Figure 3, it includes: a control module 55, a vacuum sample chamber 56, a temperature controller 58, a chip thermometer 59, a vacuum meter 60, a triple frequency signal acquisition box 7, a double frequency signal acquisition box 8, a data acquisition module 9, a sample holder 43 and a variable temperature sample rod 57.

The sample to be tested is mounted on the sample holder 43, and the variable temperature sample rod 57 is used to fix the sample holder 43 and is in the vacuum sample chamber 56. The four terminals on the first conductive strip 4 are connected to the triple frequency signal acquisition box 7, and the four terminals on the second conductive strip 5 are connected to the double frequency signal acquisition box 8.

The data acquisition module uses a synchronous data acquisition card. In the triple frequency signal acquisition box 7 and the double frequency signal acquisition box 8, the amplification factor of the first amplifier 17, the second amplifier 18, the third amplifier 35 and the fourth amplifier 36 is 10 times; the amplification factor of the first secondary amplifier 12 and the second secondary amplifier 32 is 100 times.

The system works as follows:

Step 1: evacuate the vacuum sample chamber 56.

Step 2: Change the temperature of the sample holder 43 , use the triple frequency signal acquisition box 7 to measure the change of the resistance of the first conductive strip 4 with temperature in the expected measurement temperature range, and calculate the resistance temperature coefficient β ₁ of the first conductive strip 4 .

Step 3, set the size of the first variable resistor 16 in the triple frequency signal acquisition box 7 so that its resistance value is slightly larger than the maximum resistance value of the first conductive strip 4 within the expected measurement temperature range; set the size of the second variable resistor 34 on the double frequency signal acquisition box 8 so that it is slightly larger than the maximum resistance value of the second conductive strip 5 within the expected measurement temperature range.

When the sample temperature is balanced at a certain value T ₀ , the control module 55 measures the resistance R _br of the first variable resistor 16 and the resistance R _Q1 of the first conductive strip 4 according to the triple frequency signal acquisition box 7, and calculates the ratio of R _Q1 /R _br at the temperature; the control module 55 measures the resistance R _ar of the second variable resistor 34 and the resistance R _Q2 of the second conductive strip 5 according to the double frequency signal acquisition box 8, and calculates the ratio of R _Q2 /R _ar at the temperature.

Step 4: The control module 55 sets the output gains of the first digital-to-analog conversion chip 19 and the second digital-to-analog conversion chip 37 according to the values of R _Q1 /R _br and R _Q2 /R _ar .

Step 5, the control module 55 controls the AC current source 10 in the triple frequency signal acquisition box 7 to input a sinusoidal AC current with a certain amplitude and angular frequency to the first conductive strip 4, and controls the DC/AC constant current source 30 in the double frequency signal acquisition box 8 to input a DC current with an amplitude of _ID to the second conductive strip 5.

The control module 55 collects the triple frequency signal amplitude |V _3ω | and the real-time phase of the triple frequency signal obtained from the first conductive strip 4, the real-time phase of the baseband voltage signal obtained from the sampling resistor 14, and the real-time phase of the double frequency signal obtained from the second conductive strip 5;

The initial phase Φ _3ω of the triple frequency signal and the initial phase Φ _2ω of the double frequency signal based on the excitation current I(t) = I ₀ sin(ωt) are calculated, and the phases Φ(2ω) ₁ and Φ(2ω) ₂ of the temperature fluctuation on the first conductive strip 4 and the second conductive strip 5 are further obtained, where Φ(2ω) ₁ = Φ _3ω +π/2, Φ(2ω) ₂ = Φ _2ω .

Step 6: Change the excitation current angular frequency ω to obtain a series of |V _3ω |, Φ(2ω) ₁ and Φ(2ω) ₂ corresponding to different frequencies.

Step 7: Calculate the in-plane thermal conductivity, in-plane thermal diffusivity and volumetric heat capacity of the sample at this temperature.

The following are the data measured based on the above steps:

FIG14 is a trend diagram of the amplitude of the tripled frequency signal of the first conductive strip in a thin film according to an embodiment of the present invention as the frequency of the excitation current changes. FIG15 is a trend diagram of the phase of the temperature fluctuation on the first conductive strip and the second conductive strip in a thin film according to an embodiment of the present invention as the frequency of the excitation current changes. FIG14 and FIG15 respectively show the trends of the amplitude of the tripled frequency signal |V _3ω | of the 83.5nm silicon nitride thin film sample measured at room temperature, the phase Φ(2ω) ₁ of the temperature fluctuation on the first conductive strip 4, and the phase Φ(2ω) ₂ of the temperature fluctuation on the second conductive strip 5 as the frequency of the excitation current changes f (f＝ω/2π).

It can be understood that the excitation current is the current output by the AC current source module, and the detection current is the DC current output by the DC/AC constant current source module. In the embodiment of the utility model, the excitation current amplitude is I ₀ =0.10mA (RMS unit), and the detection current amplitude is I _DC =0.10mA. As shown in FIG. 14 and FIG. 15, the measured triple frequency signal amplitude is less than 100μV, and the experimental data is very smooth.

Furthermore, calculation and M(2ω)·N(2ω), where N(2ω)=[Φ(2ω) ₁ -Φ(2ω) ₂ ]/D, M(2ω)=N(2ω)/tan(3π/2-Φ(2ω) ₁ ), where D is the distance between the first conductive strip 4 and the second conductive strip 5, and M(2ω) and N(2ω) are intermediate quantities calculated based on the temperature fluctuation phases Φ(2ω) ₁ and Φ(2ω) ₂ .

Furthermore, the temperature fluctuation amplitude |ΔT ₁ | of the first conductive strip 4 corresponding to each excitation current of different frequencies is calculated according to β ₁ and |V _3ω |, where _RS1 is the resistance of the first conductive strip 4.

FIG. 16 is a diagram of a thin film according to an embodiment of the present invention. The schematic diagram of the measurement results with the change of the temperature fluctuation amplitude |ΔT ₁ | of the first conductive strip is shown in FIG16. Plotting |ΔT ₁ | yields a straight line. Based on the slope K ₁ of the fitted line, the in-plane thermal conductivity κ _|| of the film sample to be tested is calculated to be 2.16 Wm ^-1 K ^-1 (κ _|| = _PL K ₁ /2d, where _PL is the AC heating power amplitude per unit length of the first conductive strip, and d is the film thickness).

FIG17 is a schematic diagram of the measurement results of the angular frequency ω of the excitation current in a thin film according to an embodiment of the present invention varying with M(2ω)·N(2ω). As shown in FIG17 , a straight line is obtained by plotting ω against M(2ω)·N(2ω). By fitting the data using a straight line passing through the origin, it is obtained that the in-plane thermal diffusivity α _|| of the thin film sample is 1.09× ^{10-6 m2s -1} (α _|| ＝ _K2 , where _K2 is the slope of the fitting line), and the volume heat capacity _Cv of the sample is 1.99× ¹⁰⁶ Jm ^{-3K -1} ( _Cv ＝κ _|| /α _|| ).

It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

The above specific implementations do not constitute a limitation on the protection scope of the utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims (5)

1. A device for measuring thermal physical quantities in a film surface, characterized in that it is applied to the measurement of thermal conductivity, thermal diffusivity and volume heat capacity in a self-supporting film surface, and the device for measuring thermal physical quantities in a film surface comprises: A triple frequency signal acquisition box, a double frequency signal acquisition box, a data acquisition module and a control module; The triple frequency signal acquisition box comprises an AC current source module, a baseband signal elimination circuit, a first secondary amplifier, a first matrix switch and a sampling resistor; the triple frequency signal acquisition box is used to collect triple frequency signals; The AC current source module is connected to the first conductive strip, the first conductive strip is connected to the baseband signal elimination circuit, the baseband signal elimination circuit is connected to the first secondary amplifier, the first secondary amplifier is connected to the first matrix switch, the first matrix switch is connected to the data acquisition module; the sampling resistor is connected to the first conductive strip and the first matrix switch respectively; The double frequency signal acquisition box comprises a DC/AC constant current source module, a DC signal elimination circuit, a second secondary amplifier and a second matrix switch; the double frequency signal acquisition box is used to collect double frequency signals; The DC/AC constant current source module is connected to the second conductive strip, the second conductive strip is connected to the DC signal elimination circuit, the DC signal elimination circuit is connected to the second secondary amplifier, the second secondary amplifier is connected to the second matrix switch, and the second matrix switch is connected to the data acquisition module; The AC current source module, the baseband signal elimination circuit and the first matrix switch are all connected to the control module in communication; the DC/AC constant current source module, the DC signal elimination circuit and the second matrix switch are all connected to the control module in communication; The control module is connected to the data acquisition module and is used to calculate the thermal physical quantity within the film surface according to the triple frequency signal and the double frequency signal. 2. The measuring device according to claim 1 is characterized in that the baseband signal elimination circuit comprises: a first variable resistor, a first digital-to-analog conversion chip, a first digital output circuit, a first amplifier and a second amplifier, wherein the first amplifier and the second amplifier have the same amplification factor; the first conductive strip and the first variable resistor are connected in series; the input end of the first amplifier is respectively connected to the two ends of the first conductive strip; the input end of the second amplifier is respectively connected to the two ends of the first variable resistor; the output end of the second amplifier is connected to the first digital-to-analog conversion chip; the first digital output circuit is connected to the first digital-to-analog conversion chip; The first differential input end of the first secondary amplifier is connected to the output end of the first amplifier and the first input end of the first matrix switch respectively; the second differential input end of the first secondary amplifier is connected to the first digital-to-analog conversion chip and the third input end of the first matrix switch respectively; the output end of the first secondary amplifier is connected to the second input end of the first matrix switch; The triple frequency signal acquisition box further includes a sampling resistor amplifier; the input end of the sampling resistor amplifier is respectively connected to the two ends of the sampling resistor, and the output end of the sampling resistor amplifier is connected to the fourth input end of the first matrix switch; The DC signal elimination circuit includes: a second variable resistor, a second digital-to-analog conversion chip, a second digital output circuit, a third amplifier and a fourth amplifier, wherein the third amplifier and the fourth amplifier have the same amplification factor; the second conductive strip and the second variable resistor are connected in series; the input end of the third amplifier is respectively connected to the two ends of the second conductive strip; the input end of the fourth amplifier is respectively connected to the two ends of the second variable resistor; the output end of the fourth amplifier is connected to the second digital-to-analog conversion chip; the second digital output circuit is connected to the second digital-to-analog conversion chip; The first differential input terminal of the second secondary amplifier is respectively connected to the output terminal of the third amplifier and the first input terminal of the second matrix switch; the second differential input terminal of the second secondary amplifier is respectively connected to the second digital-to-analog conversion chip and the third input terminal of the second matrix switch; the output terminal of the second secondary amplifier is connected to the second input terminal of the second matrix switch. 3. The measuring device according to claim 1, characterized in that the data acquisition module comprises a first input terminal, a second input terminal and a third input terminal; The first input terminal is connected to the first output terminal of the first matrix switch; the second input terminal is connected to the second output terminal of the first matrix switch; and the third input terminal is connected to the output terminal of the second matrix switch. 4. The measuring device according to claim 2 is characterized in that the data acquisition module comprises a synchronous data acquisition card or a phase-locked amplifier circuit. 5. The measuring device according to claim 2, characterized in that the triple frequency signal acquisition box further comprises a first interaction unit; The first interaction unit includes a first knob, a first panel signal input port, and a first panel signal output port; The first knob is connected to the first variable resistor and is used to adjust the value of the first variable resistor; the first panel signal input port is connected to the wiring terminal of the first conductive strip, and the first matrix switch is connected to the data acquisition module through the first panel signal output port; The double frequency signal acquisition box also includes a second interaction unit; The second interaction unit includes a second knob, a second panel signal input port, and a second panel signal output port; The second knob is connected to the second variable resistor for adjusting the size of the second variable resistor; the second panel signal input port is connected to the connection terminal of the second conductive strip, and the second matrix switch is connected to the data acquisition module through the second panel signal output port.