JP2022176741A - temperature measuring device - Google Patents

Abstract

To provide a temperature measuring device capable of improving reliability by reducing effects of a distance between antennas and a temperature of a piezoelectric substrate and effects of noise that does not pass through the piezoelectric substrate even when the distance between the antennas for wireless transmission/reception changes continuously and even when the temperature of the piezoelectric substrate changes continuously.SOLUTION: A temperature measuring device 10 uses a surface acoustic wave of a piezoelectric substrate 1 to measure a temperature via radio in a non-powered manner. Temperature calculation means 75 of a measurement unit 3 is configured to translate electrical signals received by a receiving antenna 5 for a measurement unit from a frequency domain into a time domain, to determine a time range to be analyzed on the basis of, time delayed due to propagation through the piezoelectric substrate as surface acoustic waves, and calculate the temperature of the piezoelectric substrate within the determined analysis time range.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a wireless temperature measuring device that measures temperature using surface acoustic waves through wireless communication.

In recent years, in the assembly manufacturing process of various industrial products or home appliances, or in the manufacturing process of devices such as various electronic parts, various batteries, or substrates on which electronic parts are mounted, which are the constituent parts of those products, heat treatment Furnaces have also diversified, and the functions of each have greatly improved.

Moreover, the temperature control of the object to be heated has come to greatly affect the performance of the product.

In general, in the case of a small furnace or a furnace in which the object to be heated is transported very slowly, a thermocouple is attached inside the furnace to monitor the temperature transition of the object to be heated, and it is connected to the measurement part outside the furnace. It may be possible to measure

However, in the case of a large furnace with a long transport distance, a furnace with an extremely fast transport speed, or a structure such as a shutter in the transport path, the temperature when the thermocouple inside the furnace is connected to the measurement part outside the furnace Measurement is often difficult. When using a thermocouple in such a furnace, a method of connecting a short thermocouple to a wireless unit and inserting it into the furnace together with the wireless unit to wirelessly transmit the thermocouple information to the measurement unit outside the furnace, or There is also a method in which a data storage device is mounted in the wireless unit to store information such as thermocouple information, and the data information is extracted from the storage device after the wireless unit is carried out of the furnace. However, depending on the temperature inside the furnace, it may exceed the heat resistance temperature of the battery used as the drive power source for the transmitter or data storage device when transmitting wirelessly, or the transmitter or storage device itself, and it may not be possible to use it. many in Therefore, a sensing technology that measures temperature using surface acoustic waves of a piezoelectric substrate is used as a wireless measurement sensor that does not include a battery, a transmitter, or a storage device that has a low heat resistance. Are known.

FIG. 10 is an explanatory diagram of a conventional temperature measuring device 20 disclosed in Patent Document 1. As shown in FIG. Patent Literature 1 describes an example of a wireless, non-powered temperature measuring device in which comb-shaped electrodes are provided on a piezoelectric substrate. The temperature measurement device 20 of Patent Document 1 includes a piezoelectric substrate 21 that is composed of a piezoelectric material that exhibits a piezoelectric effect and that can propagate surface acoustic waves, and a piezoelectric substrate 21 that receives a wirelessly transmitted drive signal and wirelessly transmits a response signal. an antenna 22 that converts between radio waves and high-frequency electric signals; a first comb-shaped electrode 23 that is surface acoustic wave conversion means; and a second comb-shaped electrode 24 connected to one terminal of the variable impedance sensor 25 . The second comb-shaped electrode 24 has surface acoustic wave reflection means for reflecting the surface acoustic wave excited by the first comb-shaped electrode 23 which is the surface acoustic wave conversion means. Temperature measurement is performed by analyzing surface acoustic wave characteristics affected by impedance fluctuations.

In addition, in a wireless, non-powered temperature measuring device using pectinate electrodes, the method of Patent Document 2 is known as an example of means for eliminating the influence of fluctuations in the distance between wireless antennas. FIG. 11 is an explanatory diagram of a conventional temperature measuring device 30 disclosed in Patent Document 2. As shown in FIG. A temperature measuring device 30 of Patent Document 2 includes a piezoelectric substrate 31 , a first comb-shaped electrode 32 , a second comb-shaped electrode 33 , a third comb-shaped electrode 34 , and a measuring device 35 . The first comb-shaped electrode 32 is electrically connected to an antenna 37 for transmitting and receiving radio waves to and from an external antenna 36 and is located on the piezoelectric substrate 31 . The second comb-shaped electrode 33 is electrically connected to a sensor 38 having an impedance that changes according to a physical quantity from the outside, and is positioned on the piezoelectric substrate 31 so as to face the first comb-shaped electrode 32 . ing. The third comb-shaped electrode 34 is positioned on the piezoelectric substrate 31 so as to face the first comb-shaped electrode 32 . The measuring device 35 measures the time from the transmission of radio waves by the external antenna 36 to the reception of radio waves by the external antenna 36 through the propagation of surface acoustic waves between the first comb-shaped electrode 32 and the second comb-shaped electrode 33, and the , the time from the transmission of radio waves by the external antenna 36 to the reception of radio waves by the external antenna 36 through the propagation of surface acoustic waves between the first comb-shaped electrode 32 and the third comb-shaped electrode 34 . By doing so, the effects of distance fluctuations in wireless are eliminated.

JP 2012-255706 A Japanese Patent Application Laid-Open No. 2020-112466

However, in the configuration of Patent Document 1, when analyzing the influence information of the impedance variation of the impedance variable sensor 25, the influence of the distance variation between the antennas due to movement is not taken into consideration. It is affected by unnecessary electrical signals such as reflected waves from the walls of the furnace that are received during the transmission and reception of electrical signals, so-called noise, and the problem is that it is difficult to remove this electrical noise. have.

Further, in the configuration of Patent Document 2, reflected waves with different propagation distances of the surface acoustic waves propagating on the piezoelectric substrate 31 are used to cancel the influence of the propagation time due to the variation in the distance between the antennas 36 and 37 . However, especially when the distance between the antennas 36 and 37 changes continuously, the situation inside the furnace changes every moment. The state of the electrical noise generated also fluctuates from moment to moment.

The present invention solves the above-described conventional problems, and even when the distance between antennas for wireless transmission and reception changes continuously and the temperature of the piezoelectric substrate changes continuously, the distance between the antennas and the piezoelectric It is an object of the present invention to provide a temperature measuring device capable of improving reliability by reducing the influence of substrate temperature and the influence of noise that does not pass through a piezoelectric substrate.

In order to achieve the above object, a temperature measuring device according to one aspect of the present invention comprises:
a measuring unit including a transmitting antenna for the measuring unit that wirelessly transmits a high-frequency electrical signal and a receiving antenna for the measuring unit that receives the signal;
a piezoelectric substrate including an antenna for the piezoelectric substrate that transmits and receives electrical signals to and from the measurement unit;
An electric signal received from a transmission antenna for the measurement unit of the measurement unit provided on the piezoelectric substrate is excited on the piezoelectric substrate as a surface acoustic wave, and the surface acoustic wave propagating on the piezoelectric substrate is generated as an electric signal. A temperature measuring device comprising a comb-shaped electrode that converts into a signal,
Either one of the transmitting antenna for the measuring section and the receiving antenna for the measuring section is arranged upstream of the conveying path of the piezoelectric substrate conveyed on the linear conveying path, and downstream of the conveying path. Either the transmitting antenna for the measuring unit or the receiving antenna for the measuring unit is arranged on the side,
The measurement unit converts the electrical signal received by the receiving antenna for the measurement unit from the frequency domain to the time domain, and the range of time to be analyzed based on the time delayed by propagating the piezoelectric substrate as a surface acoustic wave. and calculating the temperature of the piezoelectric substrate within the determined analysis target time range.

As described above, according to the temperature measuring device according to the aspect of the present invention, the piezoelectric substrate, which is the object of temperature measurement, moves and the distance between the measuring unit and the piezoelectric substrate changes continuously. An electric signal transmitted from the piezoelectric substrate is received and excited as a surface acoustic wave by comb-like electrodes on the piezoelectric substrate. When this surface acoustic wave propagates on the piezoelectric substrate, it is converted into an electrical signal by the comb-shaped electrodes and transmitted to the measuring unit while having information of temperature influence as a frequency characteristic. At this time, since the time delay due to distance is constant, it is possible to distinguish time delays such as reflected waves that are received by the measurement unit without reaching the piezoelectric substrate as noise. The temperature of the piezoelectric substrate can be calculated by the temperature calculating means by selectively analyzing the electrical signal that has passed through the piezoelectric substrate as a surface acoustic wave.

Therefore, even if the distance between the antennas for wireless transmission and reception changes continuously and the temperature of the piezoelectric substrate changes continuously, the effect of the distance between the antennas and the temperature of the piezoelectric substrate and the fact that the piezoelectric substrate does not pass the Reliability can be improved by reducing the influence of noise.

Explanatory drawing of a temperature measuring device according to an embodiment of the present invention Detailed explanatory diagram of the temperature measuring device according to the embodiment of the present invention Explanatory diagram of generation of unnecessary noise in the embodiment of the present invention Explanatory diagram of a method for determining analysis target time according to the embodiment of the present invention Explanatory drawing of the positional relationship of the temperature measuring device according to the embodiment of the present invention. Explanatory drawing of the temperature measuring device in the first modified example of the embodiment of the present invention Detailed explanatory diagram of the temperature measuring device in the first modified example of the embodiment of the present invention Explanatory diagram of vertical polarization and horizontal polarization Explanatory drawing of the temperature measuring device in the second modified example of the embodiment of the present invention Explanatory drawing showing a conventional temperature measuring device Explanatory diagram showing a conventional temperature measuring device

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(embodiment)
FIG. 1 is an explanatory diagram of a temperature measuring device 10 according to an embodiment of the invention.

A temperature measuring device 10 includes a piezoelectric substrate 1 , a measuring section 3 , and comb-like electrodes 8 and 9 .

The measurement unit 3 includes a transmitter 4a having a transmission antenna 4 for the measurement unit that transmits a high-frequency electrical signal, and a receiver 5a that has a reception antenna 5 for the measurement unit that receives the high-frequency electrical signal. A transmitter 4a and a receiver 5a are connected to the main body 3a. The measurement main unit 3a controls transmission and reception of high-frequency electrical signals.
The piezoelectric substrate 1 includes a piezoelectric substrate receiving antenna 2a for receiving an electrical signal transmitted from a transmitting antenna 4 for the measuring section, and a piezoelectric substrate for transmitting an electrical signal to a receiving antenna 5 for the measuring section. and a transmitting antenna 2b. When the piezoelectric substrate 1 whose temperature is to be measured is conveyed along the conveying path 6 in the furnace 7 in a wireless and non-powered state, the transmission antenna 4 for the measurement section connected to the measurement body section 3a and the measurement The receiving antennas 5 for the parts are installed outside the furnace 7 and at, for example, the upstream end and the downstream end of the transport path 6 along which the piezoelectric substrate 1 moves linearly. Here, the transmitting antenna 4 for the measuring section and the receiving antenna 5 for the measuring section are not limited to being installed on the upstream side and the downstream side of the conveying route 6 respectively. A mode in which they are respectively installed on the side and the upstream side may also be used.

Comb-shaped electrodes 8 and 9 are provided on the piezoelectric substrate 1 as a first comb-shaped electrode 8 and a second comb-shaped electrode 9, and transmit electricity received from the transmission antenna 4 for the measuring section 3 of the measuring section 3. A signal is excited as a surface acoustic wave on the piezoelectric substrate 1, and the surface acoustic wave propagating on the piezoelectric substrate 1 is converted into an electric signal.

Furthermore, the temperature measuring device 10 includes a temperature calculating means 75 connected to the measuring body 3a. The temperature calculation means 75 may be arranged inside the measurement main body 3a, or may be arranged outside the measurement main body 3a. The temperature calculation means 75 converts the electric signal received by the receiving antenna 5 for the measurement unit from the frequency domain to the time domain, and calculates the analysis target time based on the time delayed by propagating the piezoelectric substrate 1 as a surface acoustic wave. A range is determined, and the temperature of the piezoelectric substrate 1 within the determined analysis target time range is calculated. That is, the temperature calculation means 75 calculates the frequency of the surface acoustic wave because the frequency characteristics of the surface acoustic wave change due to factors such as a change in the spacing between the comb-shaped electrodes 8 and 9 provided on the piezoelectric substrate 1 . The change in properties can be associated with the temperature of the piezoelectric substrate 1, and the temperature of the piezoelectric substrate 1 is calculated by analyzing the high-frequency electrical signal.

The temperature measurement device 10 according to the embodiment of the present invention will be described in further detail below.

FIG. 2 is a detailed explanatory diagram of the temperature measuring device 10 according to the embodiment of the present invention. As described above, the piezoelectric substrate 1 is provided with the piezoelectric substrate receiving antenna 2a for receiving an electric signal from the measuring unit 3 and the piezoelectric substrate transmitting antenna 2b for transmitting the electric signal. The receiving antenna 2a is electrically connected to a first comb-shaped electrode 8 provided on the piezoelectric substrate 1, for example, at one end in the longitudinal direction. It is electrically connected to the second comb-shaped electrode 9 provided on the other end side in the longitudinal direction. The first comb-shaped electrode 8 and the second comb-shaped electrode 9 are arranged on the piezoelectric substrate 1 at positions facing each other.

The measurement unit 3 sweeps a predetermined frequency, for example, 420 to 430 MHz, which is specified low power under the Radio Law, or a high frequency including a frequency in the range of 915 to 930 MHz for RFID, and transmits an electric signal from the transmitter 4a. It is transmitted wirelessly from the antenna 4 .

A high-frequency electrical signal transmitted from the transmitting antenna 4 of the transmitter 4a connected to the measurement main body 3a is received by the receiving antenna 2a of the piezoelectric substrate 1, and the first comb-shaped electrode is formed on the piezoelectric substrate 1. At 8, it is excited as a surface acoustic wave.

After that, the excited surface acoustic wave propagates on the piezoelectric substrate 1, reaches the second comb-shaped electrode 9, is converted into an electrical signal again, and is transmitted from the transmission antenna 2b of the piezoelectric substrate 1. FIG.

The electrical signal transmitted from the transmitting antenna 2b is received by the receiving antenna 5 of the receiver 5a connected to the measuring body 3a.

The temperature calculation means (temperature calculation unit) 75 connected to the measurement main unit 3a analyzes the electrical signal received by the reception antenna 5 within the analysis target time range, thereby calculating the temperature of the piezoelectric substrate 1. Calculated by the calculating means 75 . The details of how the measurement unit 3 determines the time to be analyzed will be described later.

According to the above-described configuration, it is possible to extract and analyze only high-frequency electrical signals propagated as surface acoustic waves on the piezoelectric substrate 1 without being affected by changes in distance due to the following effects. Even when the distances between the piezoelectric substrate 1 and the antennas 4, 2a, 5, 2b of the measuring unit 3 change continuously, the temperature measurement accuracy of the temperature measuring device 10 can be improved.

FIG. 3 is an explanatory diagram of propagation of a high-frequency electrical signal transmitted from the measurement unit 3. As shown in FIG. Regarding wireless transmission and reception in general space, not only transmission and reception between the transmission antenna 4 of the transmitter 4a connected to the measurement main body 3a and the reception antenna 2a of the piezoelectric substrate 1, but also transmission from the transmission antenna 4 The generated electric signal 71 propagates in each direction around the transmitting antenna 4 and is also reflected by various objects such as the metal wall 13 existing around the transmitting antenna 4 . Although the intensity level of the reflected signal varies, the reflected electrical signal reaches the receiving antenna 5 of the receiver 5a and is received as an unnecessary electrical signal, so-called reflected noise 11. FIG. Other typical unnecessary electrical signals include direct waves 12 that propagate directly from the transmitting antenna 4 to the receiving antenna 5 . In order for the temperature calculation means 75 to analyze the temperature of the piezoelectric substrate 1 with high accuracy, the piezoelectric substrate 1 is reached and excited by the first comb-shaped electrode 8 as a surface acoustic wave, and the surface elastic wave is generated on the piezoelectric substrate 1 . After propagating as a wave and receiving the influence of temperature as a frequency characteristic, it reaches the opposing second comb-shaped electrode 9 and is converted into an electrical signal again, transmitted from the piezoelectric substrate 1 and reflected back. Only the electric signal of the wave needs to be extracted by the temperature calculation means 75 and analyzed by the temperature calculation means 75 . Therefore, the reflection noise 11 and the direct wave 12 that do not pass through the piezoelectric substrate 1 as surface acoustic waves must be removed as much as possible in the temperature calculation means 75 so as not to be analyzed.

FIG. 4 is an explanatory diagram for removing the noise 11 and extracting a necessary electric signal in the temperature calculating means 75. As shown in FIG. The transmission/reception between the measurement unit 3 and the piezoelectric substrate 1 is an exchange of high-frequency electrical signals, that is, information in the frequency domain. By inverse Fourier transforming this information, it can be treated as information in the time domain. By converting to the time domain, a time delay occurs between the electrical signal transmitted and received through space and the electrical signal transmitted and received through the piezoelectric substrate 1 as a surface acoustic wave. As a result of an experiment conducted by the inventor, the delay time when passing over the piezoelectric substrate 1 was about 200 ns, which corresponds to spatial propagation of about 60 m when converted to a spatial distance. In the time domain information, by utilizing the delay time when the surface acoustic wave passes over the piezoelectric substrate 1, the electrical signal returning after passing over the piezoelectric substrate 1 can be extracted as the time to be analyzed. It becomes possible.

Specifically, in FIG. 4, information in the time domain is obtained by inverse Fourier transforming the information in the frequency domain (see (1) to (2) in FIG. 4).

Next, from the obtained information in the time domain, only the data of a predetermined time width delayed through the piezoelectric substrate 1 is cut out (see (2) and (3) in FIG. 4).

This cut out information in the time domain is transformed into the frequency domain by Fourier transform (see (3) to (4) in FIG. 4), so that the surface acoustic wave passes through the piezoelectric substrate 1 and returns. Only electrical signals can be analyzed in the frequency domain.

As described above, in order to remove reflection noise, it is necessary to accurately extract only the information that has passed through the piezoelectric substrate 1 in the time domain. Since it varies, it is conventionally necessary to remove this time delay due to the distance between the antennas as well as the noise. However, it was found that this need not be removed in the present embodiment as follows.

FIG. 5 is an explanatory diagram of the positional relationship of the temperature measuring device 10 according to the embodiment of the present invention. A high-frequency electrical signal transmitted from the transmitting antenna 4 of the measuring unit 3 propagates through space, reaches the receiving antenna 2a of the piezoelectric substrate 1, propagates on the piezoelectric substrate 1 as a surface acoustic wave, and is transmitted from the transmitting antenna 2b. Then, it propagates through the space again and is received by the receiving antenna 5 of the measuring unit 3 . At this time, let us look at the total distance over which the high-frequency electrical signal propagates through space from the transmitting antenna 4 to the receiving antenna 5 . Along the conveying path 6, the space is propagated when the piezoelectric substrate 1 is at the position of the distance A1 from the transmitting antenna 4 and when the piezoelectric substrate 1 is at the position of the distance A2 from the transmitting antenna 4 from the distance A1. Since the total distance is A1+B1=A2+B2, regardless of the position of the piezoelectric substrate 1 on the transport path 6, the distance propagated through space is the same, that is, the time delay due to propagation through space does not change. It will be.

Therefore, since the analysis target time considering the delay time in the time domain does not change due to the movement of the piezoelectric substrate 1, the analysis can be performed with the analysis target time optimized as the initial conditions for measurement.

Note that the piezoelectric substrate 1 receives an electrical signal from the receiving antenna 2a of the piezoelectric substrate 1, propagates it on the piezoelectric substrate 1 as a surface acoustic wave, and then transmits the electrical signal from the transmitting antenna 2b of the piezoelectric substrate 1 as an electrical signal. Let us consider the effect of the distance traveled by . The inventor measured the time required for the surface acoustic wave to pass through the piezoelectric substrate 1 through an experiment, and the result was about 100 ns. For this reason, considering the general transport speed of the piezoelectric substrate 1, the movement distance within 100 ns can be ignored.

Regarding the influence of the temperature of the piezoelectric substrate 1 on the surface acoustic wave, changes in frequency characteristics due to changes in temperature, for example, expansion or contraction of the piezoelectric substrate 1 itself due to changes in temperature, or The frequency characteristics of the surface acoustic wave change due to factors such as a change in the distance between the first comb-shaped electrode 8 and the second comb-shaped electrode 9 provided on the piezoelectric substrate 1 . Since the change in the frequency characteristics of the surface acoustic waves can be associated with the temperature of the piezoelectric substrate 1, the temperature of the piezoelectric substrate 1 can be measured by the temperature calculating means 75 by analyzing the high-frequency electrical signal. can.

As described above, according to the present embodiment, in an environment where the piezoelectric substrate 1 to be measured for temperature moves and the distance between the measuring unit 3 and the piezoelectric substrate 1 changes continuously, The electric signal 71 is received and excited as a surface acoustic wave by the first comb-shaped electrode 8 on the piezoelectric substrate 1 . When this surface acoustic wave propagates on the piezoelectric substrate 1 , it is converted into an electric signal by the second comb-shaped electrode 9 and transmitted to the measurement unit 3 while having temperature influence information as a frequency characteristic. At this time, since the time delay due to the distance is constant, time delays such as reflected waves received by the measurement unit 3 without reaching the piezoelectric substrate 1 can be distinguished as noise 11, and the temperature of the piezoelectric substrate 1 can be determined. The temperature of the piezoelectric substrate 1 can be calculated by the temperature calculating means 75 by selectively analyzing the electrical signal that has passed through the piezoelectric substrate 1 as a surface acoustic wave for analysis.

Therefore, even if the distance between the antennas 4, 2a, 5, 2b for wireless transmission and reception changes continuously and the temperature of the piezoelectric substrate 1 changes continuously, the distance between the antennas 4, 2a, 5, 2b Reliability can be improved by reducing the effects of the distance and the temperature of the piezoelectric substrate 1 and the effects of the noise 11 that does not pass through the piezoelectric substrate 1 .
(Modification)
The configuration of FIG. 1 utilizes the transmission characteristics S21 of the piezoelectric substrate 1 due to high-frequency surface acoustic waves, but as a modification, a configuration utilizing the reflection characteristics S11 shown in FIG. 6 is also possible. In the configuration of FIG. 6, the piezoelectric substrate 1 moves along the transport path 6 connecting the transmitting antenna 4 and the receiving antenna 5 of the measuring unit 3, and the piezoelectric substrate 1 is provided with the transmitting/receiving antenna 14. As shown in FIG.

FIG. 7 is a detailed explanatory diagram of the temperature measuring device 10B in a modification of the embodiment of the invention of FIG. The piezoelectric substrate 1 is provided with a measuring section 3 and a transmitting/receiving antenna 14 for transmitting or receiving an electric signal. The transmitting/receiving antenna 14 is electrically connected to a comb-shaped electrode 15 provided on the piezoelectric substrate 1 . A reflector 16 is arranged on the piezoelectric substrate 1 at a position facing the comb-shaped electrode 15 .

According to such a configuration, a high-frequency electric signal transmitted from the transmitting antenna 4 of the transmitter 4a connected to the measurement main body 3a is received by the transmitting/receiving antenna 14, and a comb-shaped electric signal is formed on the piezoelectric substrate 1. After being excited by the electrode 15 as a surface acoustic wave, the excited surface acoustic wave propagates on the piezoelectric substrate 1, is reflected by the reflector 16, reaches the comb-shaped electrode 15, and is converted into an electric signal again. , is transmitted from the transmitting/receiving antenna 14 .

This electrical signal transmitted from the transmitting/receiving antenna 14 is received by the receiving antenna 5 of the receiver 5a connected to the measurement main body 3a.

The temperature calculation means 75 calculates the temperature of the piezoelectric substrate 1 by analyzing the electric signal received by the receiving antenna 5 .

By using the reflection characteristic S11, the delay time due to the propagation of the surface acoustic wave on the piezoelectric substrate 1 is doubled compared to when the transmission characteristic S21 is used, so the output waveform of the time delay becomes clearer. .

According to the above-described configuration, even when the reflection characteristic S11 is used, the high-frequency electric signal passing through the piezoelectric substrate 1 is not affected by the change in distance, as in the case of using the transmission characteristic S21. Therefore, the temperature measurement accuracy of the temperature measurement device 10B can be maintained even when the distance between the piezoelectric substrate 1 and the antennas of the measurement unit 3 continuously changes. I can. That is, even when the reflection characteristic S11 is used, the time domain data for determining the analysis target time is not affected by the change in distance due to the movement of the piezoelectric substrate 1, so the analysis target time is constant. You can leave it.

In order to stabilize the transmission and reception of high-frequency electrical signals between antennas, polarized waves can be used when using the pass characteristic S21. FIG. 8 is an explanatory diagram of polarization due to the arrangement of antennas. As shown in FIG. 8(a), the polarized wave by the antenna 17 perpendicular to the ground is called the vertical polarized wave 18, and as shown in FIG. 8(b), the polarized wave by the antenna 17 horizontal to the ground is Polarization is called horizontal polarization 19 . If the wavelength is longer (lower frequency) than microwaves, good communication may not be possible unless the polarization planes of the antennas on the transmitting side and the receiving side are matched. As a case in which the loss at this time is used in reverse, mutual interference can be reduced by separating the vertical and horizontal.

In the configuration shown in FIG. 9, the transmitting antenna 4 of the measuring unit 3 is vertically (vertically) arranged so as to form a vertically polarized wave 18, and the receiving antenna 5 is arranged horizontally so as to be horizontally polarized. Arranged so as to form a wave 19 . On the other hand, the receiving antenna 2a of the piezoelectric substrate 1 is arranged vertically (vertical direction) and arranged so as to form a vertically polarized wave 18, and the transmitting antenna 2b of the piezoelectric substrate 1 is arranged along the horizontal direction and horizontally polarized. Arranged so as to form a wave 19 .

In other words, by transmitting the vertically polarized wave 18 from the transmitting antenna 4 of the measuring unit 3, the receiving antenna 2a of the piezoelectric substrate 1 can easily receive it, but noise reflected by the metal wall surface of the furnace 7 or through space As a result, the electrical signal that propagates directly to the receiving antenna 5 of the measuring unit 3 has a large loss.

Further, by arranging the transmitting antenna 2b of the piezoelectric substrate 1 so as to produce a horizontally polarized wave 19, the piezoelectric substrate 1 is propagated as a surface acoustic wave, and the electric signal transmitted from the transmitting antenna 2b of the piezoelectric substrate 1 is transmitted horizontally. It becomes polarized wave 19 and can be received by the receiving antenna 5 of the measuring unit 3 with little loss.

As a result, it is possible to transmit only the electrical signal necessary for analyzing the temperature, which has propagated through the piezoelectric substrate 1 as a surface acoustic wave, without any loss.

By appropriately combining any of the various embodiments or modifications described above, the respective effects can be obtained. In addition, combinations of embodiments, combinations of examples, or combinations of embodiments and examples are possible, as well as combinations of features in different embodiments or examples.

The temperature measuring device according to the above aspect of the present invention can greatly reduce the influence of noise when measuring the temperature of a continuously moving temperature measurement object, and can improve the frequency characteristics due to the temperature of the piezoelectric substrate. Accurate analysis becomes possible. For this reason, the above aspect of the present invention is a system for measuring temperature with high accuracy wirelessly and without power supply. Alternatively, it can be applied to a heat treatment method and apparatus for performing various heat treatments such as a reflow furnace.

1 Piezoelectric substrate 2a Receiving antenna 2b Transmitting antenna 3 Measuring unit 3a Measuring body 4 Transmitting antenna 4a Transmitter 5 Receiving antenna 5a Receiver 6 Transport path 7 Furnace 8 First comb-shaped electrode 9 Second comb-shaped electrode 10 , 10B temperature measuring device 11 reflected noise 12 direct wave 13 metal wall surface 14 transmitting/receiving antenna 15 comb-like electrode 16 reflector 17 antenna 18 vertically polarized wave 19 horizontally polarized wave 20 temperature measuring device 21 piezoelectric substrate 22 antenna 23 first comb-like shape Electrode 24 Second comb-shaped electrode 25 Impedance variable sensor 30 Temperature measuring device 31 Piezoelectric substrate 32 First comb-shaped electrode 33 Second comb-shaped electrode 34 Third comb-shaped electrode 35 Measuring device 36 External antenna 37 Antenna 38 sensor 71 electrical signal transmitted from the measuring unit 75 temperature calculation means

Claims (2)

a measuring unit including a transmitting antenna for the measuring unit that wirelessly transmits a high-frequency electrical signal and a receiving antenna for the measuring unit that receives the signal;
a piezoelectric substrate including an antenna for the piezoelectric substrate that transmits and receives electrical signals to and from the measurement unit;
An electric signal received from a transmission antenna for the measurement unit of the measurement unit provided on the piezoelectric substrate is excited on the piezoelectric substrate as a surface acoustic wave, and the surface acoustic wave propagating on the piezoelectric substrate is generated as an electric signal. A temperature measuring device comprising a comb-shaped electrode that converts into a signal,
Either one of the transmitting antenna for the measuring section and the receiving antenna for the measuring section is arranged upstream of the conveying path of the piezoelectric substrate conveyed on the linear conveying path, and downstream of the conveying path. Either the transmitting antenna for the measuring unit or the receiving antenna for the measuring unit is arranged on the side,
The measurement unit converts the electrical signal received by the receiving antenna for the measurement unit from the frequency domain to the time domain, and the range of time to be analyzed based on the time delayed by propagating the piezoelectric substrate as a surface acoustic wave. and calculating the temperature of the piezoelectric substrate within the determined analysis target time range. a first comb-shaped electrode and a second comb-shaped electrode that constitute the comb-shaped electrode and are arranged on the piezoelectric substrate so as to face each other;
a first antenna constituting an antenna for the piezoelectric substrate and electrically connected to the first comb-shaped electrode;
a second antenna that constitutes an antenna for the piezoelectric substrate and is electrically connected to the second comb-shaped electrode, wherein the first comb-shaped electrode An electric signal received from a transmission antenna for the unit is excited as a surface acoustic wave on the piezoelectric substrate, and the second comb-shaped electrode converts the surface acoustic wave propagating on the piezoelectric substrate into an electric signal,
the first antenna and the second antenna are arranged in planes of polarization different from each other;
The first antenna is arranged in the same plane of polarization as either the transmission antenna for the measurement unit or the reception antenna for the measurement unit that transmits and receives electrical signals to and from the first antenna,
2. The second antenna according to claim 1, wherein said second antenna is arranged in the same plane of polarization as the other of said transmitting antenna for said measuring unit and said receiving antenna for said measuring unit that transmits and receives an electric signal to and from said second antenna. temperature measuring device.

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