KR20220149329A - A temperature estimating apparatus and method using at least one surface acoustic wave sensor - Google Patents

Abstract

The present invention relates to a temperature measuring device and a temperature measuring method, using at least one surface acoustic wave (SAW) sensor. The temperature measuring device can measure accurate temperature. To achieve the purpose of the present invention, the temperature measuring device using at least one SAW sensor includes: a signal generating unit generating a signal based on a preset frequency; a switch switching a transfer mode into a receiving mode after the generated signal is transmitted; a signal detecting unit detecting at least one of a reflected signal from the SAW sensor based on the signal transmitted to the SAW sensor after the switch is switched into the receiving mode; and a processor obtaining a resonant frequency by analyzing electricity about at least one of the detected reflected signal, and set to measure the temperature based on the obtained resonant frequency.

Description

A TEMPERATURE ESTIMATING APPARATUS AND METHOD USING AT LEAST ONE SURFACE ACOUSTIC WAVE SENSOR using at least one SAW sensor

The present invention relates to a temperature measuring apparatus and method using at least one SAW sensor.

In general, an acoustic wave propagating through the surface of an elastic body includes a bulk acoustic wave (BAW), and an acoustic wave propagating along the surface of an elastic body includes a surface acoustic wave (SAW).

A surface acoustic wave (SAW) is an acoustic wave that proceeds by generating vibration of particles on a solid surface by an external force, and is used to measure a temperature. Such a temperature sensor is called a SAW sensor.

SAW sensors are used in electronic devices for miniaturization because they can measure temperature wirelessly without requiring a separate power source.

1 is an exemplary view showing a conventional temperature measuring system.

Referring to FIG. 1 , the temperature measuring system 100 includes a sensor unit 120 and a reader unit 110 .

The sensor unit 120 includes a piezoelectric substrate 121 , a transducer 122 , a reflector 125 , and an antenna 123 . In the piezoelectric substrate 121, the delay line 124 expands or contracts according to the ambient temperature, and also affects the physical properties of the piezoelectric substrate, so that the propagation time of the surface acoustic wave or the resonance frequency is changed. By detecting the change, it becomes possible to measure the temperature.

The transducer 122 may be formed of a comb electrode, and generates a surface acoustic wave by a signal received from the antenna 111 . The reflector 125 serves to transmit the surface acoustic wave generated by the transducer 122 through the delay line 124 and reflect the surface acoustic wave at the end of the delay line to propagate it back to the transducer 122 .

When the sensor driving signal is transmitted from the reader unit 110 through the antenna, the sensor driving signal is input to the transducer 122 of the sensor unit 120 . The piezoelectric substrate 121 is vibrated by the high-frequency signal input to the transducer 122 , and accordingly, a surface acoustic wave propagating along the surface of the piezoelectric substrate 121 is generated, and the delay line 124 is propagated to propagate the reflector plate 125 . ) is propagated.

The surface acoustic wave propagated in this way is reflected by the reflector 125 , passes through the delay line 124 and the transducer 122 , and is transmitted again by the antenna of the sensor unit 120 , and the signal is received by the reader 110 . The signal received through the reader 110 may calculate the temperature of the equipment to be measured by analyzing frequency characteristics such as amplitude or frequency of the frequency.

The prior art related to such a conventional temperature measurement system is disclosed in Patent Document 1 (Korean Patent Publication No. 10-964871). However, Patent Document 1 does not disclose the contents of reflected wave cancellation.

In addition, conventionally, since the position where the SAW sensor is used is used inside the sealed chamber for the LCD high-temperature process, a natural resonant frequency mode or reflected wave is generated depending on the size of the chamber, so that the internal eddy phenomenon of radio frequency power resonant at a specific frequency is prevented. In severe cases, a residual power phenomenon occurs for several tens of nS. In addition, since most of the reflected power by the SAW sensor is temporally buried in the residual power in a state in which the residual power is generated and cannot be distinguished, the resonant frequency cannot be accurately obtained.

Accordingly, there is a need to obtain an accurate resonant frequency for the SAW sensor to measure the temperature.

Korean Patent Publication No. 10-964871

Conventionally, most of the reflected power by the SAW sensor in a state in which residual power is generated is buried in the residual power over time and cannot be distinguished, and thus the temperature cannot be accurately measured because the resonant frequency cannot be accurately obtained.

Accordingly, the present invention provides an apparatus and method for measuring a temperature using at least one SAW sensor.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the appended claims.

In order to achieve this object, the present invention provides a temperature measuring apparatus using at least one surface acoustic wave (SAW) sensor, comprising: a signal generator generating a signal based on a set frequency; a switch for switching from a transmission mode to a reception mode after transmission of the generated signal; a signal detection unit configured to detect at least a portion of a reflected signal from the SAW sensor based on a signal transmitted to the SAW sensor after the switch is switched to the reception mode; and a processor configured to obtain a resonant frequency by analyzing power of at least a portion of the detected reflected signal, and measure a temperature based on the obtained resonant frequency.

In addition, the present invention provides a method of a temperature measuring apparatus using at least one SAW sensor, comprising: generating a signal based on a set frequency; and after transmitting the generated signal, switching a switch from a transmission mode to a reception mode process, and after the switch is switched to the reception mode, the process of detecting at least a part of the reflected signal from the SAW sensor based on the signal transmitted to the SAW sensor; It may include a process of obtaining a resonant frequency by analyzing the electric power, and a process of measuring a temperature based on the obtained resonant frequency.

In addition, the present invention provides a temperature measurement system using at least one SAW sensor, comprising: at least one SAW sensor; and generating a signal based on a set frequency, and after transmitting the generated signal, detecting at least a portion of the reflected signal from the SAW sensor based on the signal transmitted to the SAW sensor, It may include a temperature measuring device configured to obtain a resonant frequency by analyzing power to a portion, and measure a temperature based on the obtained resonant frequency.

The present invention detects at least a part of a reflected signal from the SAW sensor based on a signal transmitted to the SAW sensor after transmitting a signal, after switching a switch from a transmitting mode to a receiving mode, and at least one of the detected reflected signals By analyzing the power of a part to obtain a resonant frequency, it is possible to measure the temperature more accurately.

In addition, the present invention can transmit a signal hundreds of times per second by switching the switch from the reception mode to the transmission mode when the frequency at which the signal is transmitted is within the frequency band of the SAW sensor after measuring the temperature.

In addition, in the present invention, when the switch is switched from the receiving mode to the transmitting mode, by shifting the set frequency by a certain frequency unit and resetting the frequency, signals for different frequencies can be transmitted, and a more accurate resonance frequency can be obtained. have.

In addition, according to the present invention, the temperature can be measured hundreds of times per second or more by transmitting a subsequent signal following the signal to the SAW sensor through a frequency set by shifting by a predetermined frequency unit.

In addition, the present invention can measure the temperature hundreds of times or more per second by continuously shifting the set frequency in units of a predetermined frequency while continuously performing transmission of a signal and reception of a reflected signal based on the signal.

In addition, the present invention can adaptively transmit signals sequentially by switching the switch from the transmit mode to the receive mode at the point in time when the reflected signal starts to be detected.

In addition, in the present invention, the switch detects at least a portion of the reflected signal corresponding to the point at which the detection of the reflected signal is completed from the time when the switch from the transmission mode to the reception mode is completed, so that the remaining power is lost. You can measure the exact temperature by some.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 is an exemplary view showing a conventional temperature measuring system.
2 is an exemplary view showing a temperature measuring system according to an embodiment of the present invention.
3 is a flowchart illustrating an operation of a temperature measuring apparatus according to an embodiment of the present invention.
4 is an exemplary diagram illustrating a time sequence of a temperature measuring apparatus according to an embodiment of the present invention.
5A is a time diagram illustrating an operation time of a conventional temperature measuring device.
5B is a time diagram illustrating an operating time of a temperature measuring apparatus according to an embodiment of the present invention.
6A is a result showing the power of a received reflected signal based on a conventional signal transmission.
6B is a result showing the power of a reflected signal received based on signal transmission according to an embodiment of the present invention.

The above-described objects, features and advantages will be described below in detail with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

Although the first, second, etc. are used to describe various elements, these elements are not limited by these terms, of course. These terms are only used to distinguish one component from other components, and unless otherwise stated, the first component may be the second component, of course.

In the following, that an arbitrary component is disposed on the "upper (or lower)" of a component or "top (or below)" of a component means that any component is disposed in contact with the upper surface (or lower surface) of the component. Furthermore, it may mean that other components may be interposed between the component and any component disposed on (or under) the component.

Also, when it is described that a component is “connected”, “coupled” or “connected” to another component, the components may be directly connected or connected to each other, but other components are “interposed” between each component. It is to be understood that “or, each component may be “connected”, “coupled” or “connected” through another component.

Throughout the specification, unless otherwise stated, each element may be singular or plural.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "consisting of" or "comprising" should not be construed as necessarily including all of the various components or various steps described in the specification, some of which components or some steps are It should be construed that it may not include, or may further include additional components or steps.

Throughout the specification, when “A and/or B” is used, it means A, B or A and B, unless specifically stated to the contrary, and when “C to D” is used, it means that there is no specific contrary description. Unless otherwise specified, it means that it is greater than or equal to C and less than or equal to D.

Hereinafter, an apparatus and method for measuring a temperature using at least one surface acoustic wave (SAW) sensor according to some embodiments of the present invention will be described.

2 is an exemplary view showing a temperature measuring system according to an embodiment of the present invention.

Referring to FIG. 2 , a temperature measuring system 200 according to an embodiment of the present invention measures a temperature using at least one SAW sensor 211 , 213 , and the at least one SAW sensor 210 . A measuring device 220 may be included.

According to an embodiment, the temperature measuring device 220 may include an antenna 226 , a switch 225 , a signal generator 223 , a signal detector 224 , and a processor 222 . In addition, the temperature measuring device 220 may further include a display control device 221 . Alternatively, the display control device 221 may be a separate device from the temperature measuring device 220 , and may display information received from the temperature measuring device 220 .

According to an embodiment, the SAW sensors 211 and 213 may be attached to an enclosed space (eg, a chamber) to sense an internal temperature.

The configuration of the temperature measuring system 200 shown in FIG. 2 is according to an embodiment, and the components of the temperature measuring system 200 are not limited to the embodiment shown in FIG. 2 , and some components as needed may be added, changed or deleted.

In addition, the configuration of the temperature measuring device 220 shown in FIG. 2 is according to an embodiment, and the components of the temperature measuring device 220 are not limited to the embodiment shown in FIG. 2 , and as necessary, some Components may be added, changed, or deleted.

In addition, the temperature measuring apparatus 220 according to the present invention may include interrogator hardware (not shown) capable of transmitting and receiving a radio frequency pulse signal hundreds of times per second or more.

According to an embodiment, the display control device 221 displays various data regarding the operation of the temperature sensor (eg, the SAW sensors 211 and 213), or the temperature sensor (eg, the SAW sensors 211 and 213)). It can receive input that controls the operation of The display control device 221 may transmit/receive data or signals to and from the processor 222 through a wired or wireless connection.

According to an embodiment, the signal generator 223 may receive a control signal from the processor 222 to generate a frequency and scan the frequency band of the SAW sensors 211 and 213 . The signal generator 223 may generate a signal based on a set frequency under the control of the processor 222 . For example, when the frequency band of the SAW sensors 211 and 213 is 419.3 MHz-422.3 MHz and the step is 4 kHz, the signal generator 223 transmits a signal at 419.3 MHz, and then the frequency ( Example: Retransmit the signal by shifting (419.3MHz) to 419.3MHz.

In this way, the signal generator 223 may generate a signal to be transmitted to the at least one SAW sensor 211 and 213 in units of 4 kHz until the signal reaches 422.3 MHz. The signal may be a driving signal for controlling the SAW sensors 211 and 213 to sense the temperature.

According to an embodiment, the signal detector 224 may acquire the resonance frequency by detecting the intensity (eg, signal power) of the signal reflected from the SAW sensors 211 and 213 . After the switch 225 is switched to the reception mode, the signal detection unit 224 detects at least a portion of the reflected signal from the SAW sensors 211 and 213 based on the signal transmitted to the SAW sensors 211 and 213 . can be detected. For example, the signal detection unit 224 may detect a portion of the reflected signal when the switch is switched from the transmit mode to the receive mode.

According to an embodiment, the switch 225 may switch the antenna 226 to be connected to the signal transmitter 223 or the signal detector 224 . For example, the switch 225 connects the antenna 226 and the signal transmitter 223 when operating in the transmit mode, and when operating in the receive mode, the antenna 226 and the signal detector ( 224) can be connected. When the switch 225 intends to transmit a signal, it is switched to a transmission mode under the control of the processor 222, and after a predetermined time (eg, 0.5 μS to 2 μS) passes after the signal is transmitted, reception in the transmission mode mode can be switched. The switch 225 may be switched from the reception mode to the transmission mode again under the control of the processor 222 when the processor 222 measures a temperature through a portion of the reflected signal based on the transmission of the signal. .

According to an embodiment, the antenna 226 may wirelessly transmit a signal to the at least one SAW sensor 211 , 213 . For example, the antenna 226 may transmit at least one signal to the at least one SAW sensor 211 and 213 through a time division duplexing (TDD) scheme. The at least one SAW sensor 211 and 213 may include one to a plurality (eg, 20) SAW sensors.

According to an embodiment, the processor 222 drives at least one component (eg, an antenna 226 , a switch 225 , a signal generator 223 , and a signal connected to the processor 222 ) by driving software. The detection unit 224) may be controlled based on wired communication or wireless communication. In addition, the processor 222 may perform various data processing and operations based on the wired communication or the wireless communication.

According to an embodiment, the processor 222 processes commands or data received from the antenna 226 , the switch 225 , the signal generator 223 , and the signal detector 224 , and outputs the processed data. may be transmitted to the display control device 221 .

According to one embodiment, the processor 222 obtains the resonance frequency of the SAW sensors 211 and 213 and software for temperature conversion, an algorithm for removing the eigenmode frequency or reflected wave residual power inside the high temperature chamber; and operating software such as a graphic user interface (GUI) of the display control device 221 may be recorded.

According to an embodiment, the processor 222 generates a signal through the signal generator 223 in a unit of a predetermined frequency unit (eg, 4 kHz), and transmits the generated signal through the antenna 226 in an enclosed space ( For example, the data may be transmitted to the at least one SAW sensor 211 and 213 located in the chamber). The chamber is a space in charge of high-temperature processing in the process of manufacturing the LCD.

According to an embodiment, the processor 222 may switch the switch 225 from the transmit mode to the receive mode when a predetermined time elapses after the signal is transmitted. The processor 222 may switch the switch 225 from the transmit mode to the receive mode when the reflected signal reflected from the SAW sensors 211 and 213 starts to be detected based on the signal transmission.

According to an embodiment, the processor 222 receives at least a portion of the reflected signal corresponding to the point at which the switch 225 completes the transition from the transmit mode to the receive mode to the point at which the detection of the reflected signal is completed. It can be detected through the signal detector 224 .

According to an exemplary embodiment, the processor 222 transmits at least a portion of the reflected signal corresponding to a point in time when the residual power generated based on the signal transmission is extinguished to a point in time when the detection of the reflected signal is completed by the signal detection unit. (224) can be detected.

According to an embodiment, the processor 222 analyzes the power of at least a portion of the detected reflected signal to obtain a resonant frequency for the SAW sensors 211 and 213, and a temperature based on the obtained resonant frequency (eg the internal temperature of the chamber) can be measured.

According to an embodiment, the processor 222 transmits the frequency of the bands (eg, 430/940/2400MHz) of the SAW sensors 211 and 213 in the RF interrogator (not shown) to the SAW sensor at a rate of 100 Hz to 1000 Hz. Signal transmission and reception can be alternated by changing the frequency 1000 to 4000 times per channel.

According to an embodiment, the processor 222 may obtain a maximum resonant frequency by analyzing the received power of a reflected signal measured for every transmission/reception, and may convert it into a corresponding temperature through [Equation 1] below.

In [Equation 1], the resonance frequency is the resonance frequency, the reference frequency is the reference frequency, the temp coefficient is the temperature change amount of the SAW sensor, and the offset temp is the correction coefficient.

In general, the SAW sensor is known as a linear change in temperature, but non-linear changes may occur in each section due to plating and impurities introduced during the manufacturing process. Accordingly, the processor 222 may correct the temperature by using the interval interpolation method for such correction.

According to an embodiment, the processor 222 may identify the largest frequency in the frequency of the received at least one reflected signal as the resonant frequency based on the transmission of the at least one signal.

According to an embodiment, the processor 222 may include the signal generator 223, the switch 225, and By controlling the signal detection unit 224, transmission of a signal and reception of a reflected signal based on the signal are continuously performed while continuously shifting a preset frequency (eg, 419.3 MHz) in units of the predetermined frequency (eg, 4 kHz). can do.

According to an embodiment, when the switch 225 is switched from the receive mode to the transmit mode, the processor 222 may set the frequency by shifting the set frequency by a predetermined frequency unit.

According to an embodiment, the processor 222 transmits a subsequent signal (eg, a second signal) following the signal (eg, a first signal) to the SAW sensor 211 through a frequency set by shifting in units of the predetermined frequency. , 213).

According to an embodiment, the temperature measuring device 220 may further include a communication unit (not shown). The processor 222 may transmit the measured temperature based on a part of at least one reflected signal to the display control device 221 through the communication unit (not shown) in real time.

According to an embodiment, the at least one SAW sensor 211 , 213 and the temperature measuring device 220 may perform wireless communication based on time division duplexing (TDD).

3 is a flowchart illustrating an operation of a temperature measuring apparatus according to an embodiment of the present invention. 4 is an exemplary diagram illustrating a time sequence of a temperature measuring apparatus according to an embodiment of the present invention.

Hereinafter, an operation of the temperature measuring apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4 .

According to an embodiment, the temperature measuring device 200 (eg, the processor 222 ) may transmit a signal to the SAW sensor through a switch based on a set frequency ( S310 ). The temperature measuring device 200 (eg, the processor 222 ) may transmit a signal to the at least one SAW sensor at a frequency (eg, 419.3 MHz) set through the signal generator 223 . Then, the temperature measuring device 200 (eg, the processor 222) is at least one SAW sensor 211 in units of 4 kHz from the set frequency (eg, 419.3 MHz) to the frequency band (eg, 422.3 MHz). , 213 , and transmits the generated signal to at least one SAW sensor 211 , 213 in the chamber through the switch 225 .

4 illustrates a process of obtaining the maximum resonant frequency by measuring the reflected power resonant from the SAW sensor while scanning the channel band of the SAW sensor, and converting it into a corresponding temperature.

Referring to FIG. 4 , the temperature measuring apparatus 200 (eg, the processor 222 ) may set a Tx Transmission Phase Locked Loop (PLL) frequency in a first block 411 . In addition, the temperature measuring device 200 (eg, the processor 222 ) checks the Tx PLL LD (Locked Detector) in the second block 412 and, when the set frequency is confirmed, the Tx in the third block 413 The PLL output can be enabled. A signal may be transmitted during the third block 413 .

In addition, the temperature measuring device 200 (eg, the processor 222 ) may disable the Tx PLL output in the fourth block 414 . In the fourth block 414, signal transmission may be temporarily stopped.

Referring to FIG. 3 , the temperature measuring device 200 (eg, the processor 222 ) may switch the switch from the transmit mode to the receive mode after a predetermined time has elapsed ( S312 ). The temperature measuring device 200 (eg, the processor 222 ) transmits a signal generated in units of 4 kHz from 419.3 MHz to 422.3 MHz through the signal generator 223 in the chamber through the switch 225 . After being transmitted to at least one of the SAW sensors 211 and 213 , when a predetermined time elapses, the switch may be switched from the transmission mode to the reception mode.

Referring to FIG. 4 , the temperature measuring device 200 (eg, the processor 222 ) switches the switch from the transmission mode (eg, Tx mode) to the reception mode (eg, Rx mode) in the fifth block 415 . can do it

Referring to FIG. 3 , the temperature measuring device 200 (eg, the processor 222 ) reflects from the SAW sensor based on at least a part of the signal transmitted from the SAW sensor after the switch is switched to the reception mode. A signal can be detected (S314). The temperature measuring device 200 (eg, the processor 222) may identify the level of the power intensity of the detected reflected signal.

According to an embodiment, the temperature measuring device 200 (eg, the processor 222 ) is configured to have the strength (eg, the power of the signal) reflected from the SAW sensors 211 and 213 through the signal detector 224 . ) can be detected. After the switch 225 is switched to the reception mode, the temperature measuring device 200 (eg, the processor 222 ) performs the SAW sensors 211 and 213 based on the signals transmitted from the SAW sensors 211 and 213 . ) may be detected through the signal detector 224 at least part of the reflected signal.

According to an embodiment, the temperature measuring device 200 (eg, the processor 222 ) completes the detection of the reflected signal from a point in time when the residual power for each signal generated based on the transmission of at least one signal is extinguished. At least a portion of the reflected signal corresponding to the time point may be detected through the signal detector 224 .

According to an embodiment, the temperature measuring device 200 (eg, the processor 222 ) may obtain a resonance frequency by analyzing the power of the reflected signal ( S316 ). The temperature measuring device 200 (eg, the processor 222 ) may measure the power of at least a portion of each reflected signal to identify the resonant frequencies of the corresponding SAW sensors 211 and 213 .

According to an embodiment, the temperature measuring device 200 (eg, the processor 222 ) may measure the temperature based on the acquired resonant frequency ( S318 ). The temperature measuring device 200 (eg, the processor 222) analyzes the power of at least a portion of each reflected signal to obtain a resonant frequency for each SAW sensor 211 and 213, respectively, and the obtained resonant frequency Based on this, the temperature (eg the internal temperature of the chamber) can be measured.

According to an embodiment, the temperature measuring apparatus 200 (eg, the processor 222 ) may identify whether the frequency at which the signal is transmitted is within the channel band of the SAW sensor ( S320 ). The temperature measuring device 200 (eg, the processor 222) continuously shifts in a unit of a predetermined frequency (eg, 4 kHz) within the frequency band (eg, 419.3 MHz-422.3 MHz) of the SAW sensors 211 and 213 . while transmitting a signal. The temperature measuring device 200 (eg, the processor 222 ) may identify whether a frequency of a signal transmitting a signal is within or not within the frequency band due to the frequency shifting.

The above processes ( S314 , S316 , S318 , and S320 ) are performed in the sixth block 416 of FIG. 4 .

According to an embodiment, the temperature measuring device 200 (eg, the processor 222) may switch the switch from the reception mode to the transmission mode (S322). When the temperature is measured by the processor 222 , the temperature measuring device 200 (eg, the processor 222 ) may switch the switch from the reception mode to the transmission mode so that the next signal can be transmitted.

According to an embodiment, the temperature measuring apparatus 200 (eg, the processor 222) may set the set frequency by shifting it by a predetermined frequency (S324). When the switch 225 is switched to the transmission mode, the temperature measuring device 200 (eg, the processor 222) transmits the frequency (eg, 419.3 MHz) set in the process (S310) to a predetermined frequency (eg, 4 kHz). Shift as much as possible (eg 419.7MHz).

Referring to FIG. 4 , the temperature measuring device 200 (eg, the processor 222 ) switches the switch from the receiving mode (eg, Rx mode) to the transmission mode (eg, Tx mode) in the seventh block 417 . can do it In addition, the temperature measuring device 200 (eg, the processor 222 ) may return to the first block 411 to set the transmission frequency.

5A is a time diagram illustrating an operation time of a conventional temperature measuring device. 5B is a time diagram illustrating an operating time of a temperature measuring apparatus according to an embodiment of the present invention.

Referring to FIG. 5A , in the related art, the switch is switched from the transmit mode to the receive mode at a time point T1 at which a signal is transmitted. The time (T1 to T2) 511 for which these switches are switched takes a certain time (about: 0.1 μS). In addition, after the switch is switched from the transmit mode to the receive mode (T2), a reflected signal according to signal transmission starts to be detected from a time point T4 after a predetermined time 512 (eg, 0.4 μS). The reflected signal is detected from time T4 to time T5 ( 515 ).

Then, after a predetermined time (516) has elapsed from when the switch is switched from the transmission mode to the reception mode (T2), the switch is switched from the reception mode to the transmission mode again.

However, in the related art, residual power according to signal transmission is generated for a predetermined period (T1 to T3) 514 after the signal is transmitted. Since the power to the reflected signal is measured for a certain time (515) from a certain point (eg, T4) to a certain time (T5) before the residual power is dissipated, the reflection of the SAW sensor in the state in which the residual power is generated Most of the power is temporally buried in the residual power and cannot be distinguished. Therefore, it was difficult to obtain an accurate resonant frequency according to the power of the signal.

As described above, in the related art, since the reflected wave excitation power and the SAW reflected power exist at the same time during the signal detection period by the signal detection unit after the signal is transmitted, unless the excitation power is removed, the presence or absence of the SAW reflected power cannot be checked. .

In order to solve this conventional problem, an embodiment of the present invention pushes the Tx PLL output disable 414 time point T1 forward so that the reflected wave excitation power remaining period T3 moves to the vicinity of the transmit/receive switch switch T2. , the SAW reflected power is also pulled forward by the same amount of time, so that a part of the SAW reflected power remains in the reception detection level check section to obtain the SAW resonant frequency.

Referring to FIG. 5B , in the present invention, after a predetermined time 521 has elapsed after the signal is transmitted, the switch is switched from the transmission mode to the reception mode in a predetermined period 522, and the switching transition is completed at a time point T2. During the time T5 for a portion of the reflected signal at 525 , the power of the reflected signal is analyzed. Since the residual power according to the signal transmission is generated for a predetermined period (T1 to T2) 513 after the signal is transmitted, the power of the reflected signal is analyzed at a time point T2 when the residual power is lost. Then, the switch operates from the transmit mode to the receive mode for a predetermined time ( 514 ). And, after the completion of the switching, after a predetermined time 516 has passed, the switch again switches from the reception mode to the transmission mode.

6A is a result showing the power of a received reflected signal based on a conventional signal transmission. 6B is a result showing the power of a reflected signal received based on signal transmission according to an embodiment of the present invention.

Referring to FIG. 6A , in the related art, since power for a reflected signal is measured before the residual power is lost, most of the reflected power of the SAW sensor is temporally buried in the residual power. In addition, since the residual power including the power of the reflected signal is maintained for a predetermined time 610, there is a problem in that it is difficult to identify the resonant frequency.

In addition, since the location where the conventional SAW sensor is used is inside a closed chamber for high-temperature LCD processing, a natural resonant frequency mode or reflected wave is generated according to the size of such a chamber, so that the internal eddy phenomenon of radio frequency power resonant at a specific frequency may be severe. In this case, a residual power phenomenon occurs for several tens of μS.

In this way, most of the reflected power of the SAW sensor in a state in which the residual power is generated is temporally buried in the residual power and thus cannot be distinguished.

In order to solve this problem, the present invention combines a high-speed digital signal processor (DSP)-based transmit/receive switching switch, step variable adjustment in nS units at the transmit/receive switching timing, and propagation delay analysis of the SAW sensor to remove residual power. Residual power was removed to obtain experimental results as shown in FIG. 6b below.

Referring to FIG. 6B , in the present invention, since the resonant frequency is obtained by using the power of a portion of the reflected signal after the residual power is dissipated, a more accurate resonant frequency 620 may be obtained.

Each step in each of the above-described flowcharts may be operated regardless of the illustrated order, or may be performed simultaneously. In addition, at least one component of the present invention and at least one operation performed by the at least one component may be implemented in hardware and/or software.

As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed in the present specification. It is obvious that variations can be made. In addition, although the effects according to the configuration of the present invention have not been explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

210: at least one SAW sensor
220: temperature measuring device
221: display control device
222: processor
223: signal generator
224: signal detection unit
225: switch
226: antenna

Claims (10)

In the temperature measuring device using at least one SAW (surface acoustic wave) sensor,
a signal generator for generating a signal based on a set frequency;
a switch for switching from a transmission mode to a reception mode after transmission of the generated signal;
a signal detection unit configured to detect at least a portion of a reflected signal from the SAW sensor based on a signal transmitted to the SAW sensor after the switch is switched to the reception mode;
and a processor configured to analyze power for at least a portion of the detected reflected signal to obtain a resonant frequency, and to measure a temperature based on the obtained resonant frequency.
The method of claim 1,
The processor is
After measuring the temperature, when the frequency at which the signal is transmitted is within the frequency band of the SAW sensor, the temperature measuring device is set to switch the switch from the reception mode to the transmission mode.
3. The method of claim 2,
The processor is
When the switch is switched from the reception mode to the transmission mode, the temperature measuring apparatus sets the frequency by shifting the set frequency by a predetermined frequency unit.
4. The method of claim 3,
The processor is
A temperature measuring device configured to transmit a subsequent signal following the signal to the SAW sensor through a frequency set by shifting the predetermined frequency unit.
5. The method of claim 4,
The processor is
Within the frequency band of the SAW sensor, the signal generator, the switch, and the signal detector are controlled to continuously shift the set frequency in units of the predetermined frequency while transmitting a signal and receiving a reflected signal based on the signal A temperature measuring device set up to continuously perform
The method of claim 1,
The processor is
When the generated signal is transmitted, the temperature measuring device is set to switch the switch from the transmission mode to the reception mode after a predetermined time has elapsed.
7. The method of claim 6,
The processor is
a temperature measuring device configured to switch the switch from the transmitting mode to the receiving mode at a time point when the reflected signal starts to be detected.
8. The method of claim 7,
The processor is
A temperature measuring device configured to detect, through the signal detector, at least a portion of the reflected signal corresponding to the time when the switch from the transmission mode to the reception mode is completed to the point when the detection of the reflected signal is completed.
9. The method of claim 8,
The processor is
A temperature measuring apparatus configured to detect, through the signal detector, at least a portion of the reflected signal corresponding to a point in time when the detection of the reflected signal is completed from a point in time when the residual power generated based on the signal transmission is extinguished.
The method of claim 1,
The processor is
A temperature measuring device configured to identify, as the resonant frequency, a largest frequency in a frequency of the received at least one reflected signal based on the transmission of the at least one signal.

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