JP4631615B2 - Surface acoustic wave propagation state measuring device, surface acoustic wave propagation state measuring method, environment change measuring device, environment change measuring method, and multi-round surface acoustic wave element - Google Patents

Description

  The present invention relates to a surface acoustic wave propagation state measuring apparatus that calculates a frequency change amount in a multi-circular surface acoustic wave element, and more particularly to a surface acoustic wave propagation state measuring apparatus that calculates a frequency change amount with high accuracy.

  In recent years, surface acoustic wave devices have been applied to various sensors. Sensors using surface acoustic wave elements include, for example, sensors that detect the change in the physical state from the phase change of the surface acoustic wave after multiple rounds by causing the surface acoustic wave to circulate around the propagation surface of a spherical crystal. .

  Specifically, the phase of the detection signal that has been circulated multiple times is compared with the phase of the reference signal that is used as a reference, and the change in the physical state of the propagation surface is determined by obtaining a value such as a frequency change amount from the amount of change in the phase. Detect.

  In a spherical surface acoustic wave element, a surface acoustic wave is excited on a propagation surface by a burst signal. Each time this excited surface acoustic wave makes multiple rounds on the propagation surface, energy is released as a round received signal. That is, the surface acoustic wave energy is converted and consumed as electric energy via the electroacoustic transducer (interdigital electrode).

Therefore, the matching section is made a high impedance circuit to prevent the release of surface acoustic wave energy. As a result, the surface acoustic wave can be circulated multiple times (see, for example, Patent Document 1).
JP 2005-010098 A

  However, when the burst signal passes through the interdigital electrode, waves having different phase components are generated, and the waveform of the burst signal is changed. That is, phase noise may occur.

  Furthermore, the energy due to noise may be relatively greater than the energy at the carrier frequency. In this case, since an error occurs in the measurement result, it is difficult to accurately calculate the phase change. As a result, it becomes impossible to calculate the frequency change amount or the like from the phase change amount.

  Furthermore, if a burst signal having a duration longer than one round is to be input in order to increase the signal strength of the carrier frequency, the surface acoustic wave excited by the signal input before the first round and the elasticity excited by the newly input signal are used. Interference with surface waves occurs. For this reason, it is difficult to accurately measure the phase and intensity of the surface acoustic wave signal output from the surface acoustic wave element.

Normally, when calculating the phase change, the detection signal and the reference signal have the same intensity. However, in the process of making the intensity equal, the phase of the signal changes, and the frequency change amount cannot be calculated. Sometimes.
An object of the present invention is to calculate the amount of frequency change in a multi-round surface acoustic wave element with high accuracy.

  In order to achieve the above object, the following measures are taken.

  The invention corresponding to claim 1 is connected to a multi-round surface acoustic wave element that is excited by a surface acoustic wave that circulates around the propagation surface by an input of a high-frequency burst signal having a carrier frequency, and an output from the surface acoustic wave element. A surface acoustic wave propagation state measuring device for measuring a change in frequency, wherein the multi-circular surface acoustic wave element inputs the high-frequency burst signal to the multi-circular surface acoustic wave element, and multi-circulates the propagation surface after the input. The output means for detecting the surface acoustic wave and outputting the obtained detection signal; and the ratio of one period in the carrier frequency to the circulation time required for the surface acoustic wave to make one round of the propagation surface is 1 / integer. Storage means for preliminarily storing reference signal data including a reference phase of the surface acoustic wave in the resonance state and a reference frequency for exciting the surface acoustic wave. First adjustment means for adjusting the carrier frequency of the high-frequency burst signal to a resonance frequency so that the detection signal of the surface acoustic wave is in a resonance state, and after the adjustment by the first adjustment means, the output Second adjusting means for adjusting the carrier frequency of the high-frequency burst signal so that the difference between the detection phase, which is the phase of the detection signal output from the means, and the reference phase stored in the storage means is constant; And calculating means for calculating a difference between the carrier frequency adjusted by the second adjusting means and the reference frequency stored in the storage means when the phase difference between the two becomes constant as a result of the adjustment by the second adjusting means. Is a surface acoustic wave propagation state measuring device.

  According to a second aspect of the present invention, in the surface acoustic wave propagation state measuring apparatus corresponding to the first aspect, the multi-circular surface acoustic wave element has a spherical propagation surface, and the second adjustment means includes the detection signal. The waveform of the reference signal and the waveform of the reference signal are sequentially matched from the time when the number of laps is small after the high-frequency burst signal is input, and the waveform after the time corresponding to at least 5000 times the period of the resonance frequency is matched. A surface acoustic wave propagation state measuring device that adjusts the resonance frequency so that the resonance frequency is adjusted.

  The invention corresponding to claim 3 is the surface acoustic wave propagation state measuring device corresponding to claim 1 or claim 2, wherein the high-frequency burst signal has a carrier frequency of 10 MHz or more, and is at least one round of a lap time or more. This is a surface acoustic wave propagation state measuring device composed of the following waves.

  According to a fourth aspect of the present invention, in the surface acoustic wave propagation state measuring apparatus according to any one of the first to third aspects of the present invention, the second adjustment unit is configured to generate the high frequency signal every 5 ppm of the resonance frequency. This is a surface acoustic wave propagation state measuring device that makes the carrier frequency of a burst signal variable.

  According to a fifth aspect of the present invention, in the surface acoustic wave propagation state measuring device corresponding to any one of the first to fourth aspects, the input means makes the surface acoustic wave go around the propagation surface once. It is a surface acoustic wave propagation state measuring device that inputs the high-frequency burst signal over a time that is at least twice as long as the time required for this.

  The invention corresponding to claim 6 is an environment change measuring device using the surface acoustic wave propagation state measuring device corresponding to claim 1, and is preset with respect to the environmental state around the multi-round surface acoustic wave element. Environmental storage means for storing the associated characteristic frequency and the environmental state in association with each other; comparison means for comparing the difference frequency calculated by the calculation means with the characteristic frequency stored by the environment storage means; The environmental change measuring device includes an environmental state output unit that outputs the environmental state stored by the environmental storage unit as a result of comparison by the comparison unit.

  The invention corresponding to claim 7 is a multi-surface acoustic wave device used in the surface acoustic wave propagation state measuring device corresponding to claim 1, and is installed in a non-contact manner facing the propagation surface. This is a multi-circular surface acoustic wave device including interdigital electrodes that excites surface acoustic waves by applying an electric field.

  According to an eighth aspect of the present invention, there is provided an elastic surface for measuring a change amount of an output frequency from a multi-circular surface acoustic wave element in which a surface acoustic wave that multi-circulates a propagation surface is excited by input of a high frequency burst signal having a carrier frequency A wave propagation state measurement method comprising: an input step of inputting the high-frequency burst signal to the multi-circular surface acoustic wave element; and a surface acoustic wave that circulates around the propagation surface after the input is detected and obtained. An output step for outputting the detected signal and a resonance state in which a ratio of one period in the carrier frequency to a circulation time required for one round of the surface acoustic wave to travel around the propagation surface is 1 / integer. A step of storing in advance a reference signal data including a reference phase of the surface acoustic wave and a reference frequency for exciting the surface acoustic wave; A first adjustment step for adjusting the carrier frequency of the high-frequency burst signal to a resonance frequency so that the output signal is in a resonance state, and output from the output step after adjustment by the first adjustment step A second adjustment step for adjusting a carrier frequency of the high-frequency burst signal so that a difference between a detection phase that is a phase of the detection signal and a reference phase stored in the storage step is constant; As a result of the adjustment by the step, when the phase difference between the two becomes constant, an elasticity provided with a calculation step for calculating a difference between the carrier frequency adjusted by the second adjustment step and the reference frequency stored in the storage means This is a surface wave propagation state measurement method.

  The invention corresponding to claim 9 is the surface acoustic wave propagation state measuring method corresponding to claim 8, wherein the multi-round surface acoustic wave element has a spherical propagation surface, and the second adjustment step includes the detection signal. The waveform of the reference signal and the waveform of the reference signal are sequentially matched from the time when the number of laps is small after the high-frequency burst signal is input, and the waveform after the time corresponding to at least 5000 times the period of the resonance frequency is matched. It is a surface acoustic wave propagation state measuring method for adjusting the resonance frequency so that the resonance frequency is adjusted.

  The invention corresponding to claim 10 is the surface acoustic wave propagation state measuring method corresponding to claim 8 or claim 9, wherein the high-frequency burst signal has a carrier frequency of 10 MHz or more, and at least one or more lap times. This is a surface acoustic wave propagation state measurement method consisting of the following waves.

  The invention corresponding to claim 11 is the surface acoustic wave propagation state measuring method corresponding to any one of claims 8 to 10, wherein the second adjustment step is performed at every 5 ppm of the resonance frequency. This is a surface acoustic wave propagation state measuring method in which the carrier frequency of a burst signal is variable.

  The invention corresponding to claim 12 is the surface acoustic wave propagation state measuring method corresponding to any one of claims 8 to 11, wherein the input step makes the surface acoustic wave go around the propagation surface once. This is a surface acoustic wave propagation state measuring method in which the high-frequency burst signal is input over a period of time that is more than twice as long as it takes.

  The invention corresponding to claim 13 is an environmental change measurement method using the surface acoustic wave propagation state measurement method corresponding to claim 8, and is preset with respect to the environmental condition around the multi-round surface acoustic wave element. An environmental storage step for storing the characteristic frequency associated with the environmental state, a comparison step for comparing the difference frequency calculated by the calculation step with the characteristic frequency stored by the environmental storage step, and the comparison The environmental change measuring method includes an environmental state output step of outputting the environmental state stored in the environmental storage step as a result of the comparison by the step.

<Terminology>
Here, in the present invention, the wave described as “surface acoustic wave” is a boundary wave, a corridor wave, a surface wave that circulates the inner shell, a surface acoustic wave, a leaky surface acoustic wave, a pseudo surface acoustic wave, a pseudo leak It includes all surface acoustic waves that propagate by concentrating energy on a spherical surface, such as surface acoustic waves.

  Similarly, in the present invention, a surface acoustic wave element (spherical boundary acoustic wave element) formed by a boundary with a material having a different propagation path is also an element based on a phenomenon in which an elastic wave propagates through the boundary multiple times. It is called a surface acoustic wave element. For example, in a multi-circular surface acoustic wave device, the three-dimensional substrate is not limited to a spherical device, and if the propagation path has an annular surface, a part of the spherical shape is processed into another shape such as a planar shape. The element which includes is included.

  In the present invention, the circulation speed may not be a propagation speed in a strict sense. In general, when the ambient temperature changes, the propagation speed of the surface acoustic wave changes, but the circulation length of the propagation path also changes due to thermal expansion, so these effects are superimposed and the time required for the circulation of the surface acoustic wave changes. May end up. When a propagation path is made using an anisotropic material, the propagation speed of a surface acoustic wave in a physical sense changes depending on the location. That is, in the present invention, the circulation speed refers to a speed defined by a time required to propagate the circulation path between a predetermined number of times or a predetermined position.

  In the present invention, one interdigital electrode is used to convert an electric signal into an elastic wave, but it does not exclude two or more electroacoustic transducers. For example, a pair of interdigital electrodes may be used, one for transmission and the other for reception.

<Action>
Therefore, the invention corresponding to claims 1 and 8 is the first adjusting means for adjusting the carrier frequency of the high frequency burst signal to the resonance frequency, and a predetermined multiple of the cycle of the carrier frequency from the input of the high frequency burst signal. A second adjusting means for adjusting the carrier frequency so that the phase of the detection signal output from the multi-circular surface acoustic wave element coincides with a predetermined value after the time elapses. The phase change in the state after the surface acoustic wave having a predetermined wave number is propagated after the resonance state is obtained by the configuration including the calculation means for calculating the difference between the carrier frequency adjusted by the reference frequency and the reference frequency Therefore, it is possible to suppress the influence of the interference of the surface acoustic wave that has been circulated multiple times, and to calculate the amount of change in the frequency of the surface acoustic wave propagating on the same path in the multiple lap surface acoustic wave element with high accuracy It can be.

  In the invention corresponding to claims 2 and 9, in addition to the operation corresponding to claims 1 and 8, the second adjustment means sequentially detects the waveform of the detection signal and the waveform of the reference signal after inputting the high-frequency burst signal. Since the resonance frequency is adjusted so as to match and the waveform after the time corresponding to at least 5000 times the period of the resonance frequency is matched, a change in phase due to multiple rounds can be detected with high accuracy. Propagating in this way for a long time can suppress attenuation associated with circulation when the propagation surface of the surface acoustic wave is spherical. Thereby, it can detect with practical intensity | strength.

  In the invention corresponding to claims 3 and 10, in addition to the actions corresponding to claims 1 to 2 and 8 to 9, the high frequency burst signal has a carrier frequency of 10 MHz or more, and is at least 3 minutes of the lap time. Therefore, even if the intensity of the surface acoustic wave is attenuated by multiple rounds, the phase change can be obtained.

  In the invention corresponding to claims 4 and 11, in addition to the actions corresponding to claims 1 to 3 and 8 to 10, the second adjusting means makes the carrier frequency of the high frequency burst signal variable every 5 ppm of the resonance frequency. Therefore, the waveforms can be matched with high accuracy.

  In the invention corresponding to claims 5 and 12, in addition to the actions corresponding to claims 1 to 4 and 8 to 11, the input means inputs the high-frequency burst signal over a time twice as long as the round time of one round. It is possible to suppress noise due to interference of detection signals that have been circulated multiple times.

  The invention corresponding to claims 6 and 13 is calculated by an environmental storage means for storing a characteristic frequency set in advance with respect to an environmental condition around the multi-circular surface acoustic wave element and the environmental condition, and a calculation means. A comparison means for comparing the frequency of the difference and the characteristic frequency stored by the environment storage means, and an environmental state output means for outputting the environmental state stored by the environment storage means as a result of the comparison by the comparison means. Therefore, the change in the environment can be detected from the frequency fluctuation range due to the change in the environment.

  The invention corresponding to claim 7 is a multi-surface acoustic wave device used in a surface acoustic wave propagation state measuring device, which is installed in a non-contact manner facing the propagation surface, and an electric field is applied to the propagation surface to generate the surface acoustic wave. The structure with the interdigital electrode that excites the surface wave can propagate the surface acoustic wave to the propagation surface without being affected by the mass of the interdigital electrode and the scattering effect between the interdigital electrode and the surface acoustic wave. Therefore, it is possible to provide a multi-circular surface acoustic wave device capable of calculating the frequency change amount with high accuracy.

  According to the present invention, it is possible to calculate the amount of frequency change in the multi-round surface acoustic wave element with high accuracy.

  Thereby, the change in the propagation state of the surface acoustic wave can be calculated with high accuracy from the change in the resonance frequency. For example, when a substance or molecule adheres to the surface of the multi-circular surface acoustic wave element, it can be used for changing the propagation surface (environmental change).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic diagram showing the configuration of a frequency variation calculation system according to the first embodiment of the present invention.

  As shown in FIG. 2, the multi-circular surface acoustic wave element 10 includes a spherical member 12 having a propagation surface 11 and an interdigital electrode 13. As a result, a surface acoustic wave that circulates around the propagation surface 11 is excited by the input of a high-frequency signal from the high-frequency signal source 30. Further, the surface acoustic wave that has made multiple turns is detected by the interdigital electrode 13 and measured by a digital oscilloscope DOS or the like via the switch SW.

  The propagation surface 11 has an annular surface formed of a continuous curved surface, and at least part of the annular surface circulates surface acoustic waves propagating in opposite directions excited by the interdigital electrode 13. For this purpose, a circuit route is provided.

  The spherical member 12 is a three-dimensional substrate having a propagation surface 11 in which a surface acoustic wave once excited can circulate multiple times. Here, a single crystal crystal material processed into a spherical shape is used.

  The interdigital electrode 13 is used to excite surface acoustic waves that circulate around the propagation surface in response to the input of a high-frequency burst signal and to detect surface acoustic waves that have circulated multiple times. For example, it is formed in contact with the surface of the spherical member 12 by using metal deposition and etching by a photolithography process.

  The frequency change amount calculation device (surface acoustic wave propagation state measurement device) 20 calculates the amount by which the carrier frequency of the high-frequency signal from the high-frequency signal source 30 is changed, and includes an input unit 21, an output unit 22, and a storage unit 23. , A resonance adjustment unit 24 (first adjustment unit), a waveform adjustment unit 25 (second adjustment unit), and a calculation unit 26.

  The input unit 21 has a function of setting and changing the carrier frequency of the high-frequency signal output from the high-frequency signal source 30, and inputs a high-frequency burst signal to the multi-round surface acoustic wave element 10.

  Further, the input high frequency burst signal has a carrier frequency of 10 MHz or more, and consists of a wave having a duration of at least one round or more. Thereby, the influence of both ends of the burst signal of the surface acoustic wave that circulates the propagation surface 11 of the multi-surface acoustic wave element 10 can be reduced. In addition, the amplitude of the excited surface acoustic wave can be increased.

  Normally, when a surface acoustic wave is excited with a frequency of 100 MHz or higher, if a high-frequency signal with a short pulse width (impulse in an extreme case) is used, the power of the frequency component of the high-frequency signal becomes relatively small. For this reason, it becomes difficult to perform measurement with an accuracy of 1 ppm. However, only when the phase comparison with the high frequency signal of the high frequency signal source 30 is performed using a narrow band burst signal having a specific frequency, sufficient power can be secured for the frequency component to be measured, and a measurement of 1 ppm is possible. It can be performed.

  The output unit 22 detects a surface acoustic wave that circulates around the propagation surface 11 after inputting a high-frequency burst signal by the input unit 21, and outputs the obtained detection signal to the resonance adjustment unit 24 or the waveform adjustment unit 25. is there. Note that the phase of the detection signal is obtained by heterodyne detection.

  The storage unit 23 previously stores reference signal data including the reference phase of the surface acoustic wave in the resonance state and a reference frequency for exciting the surface acoustic wave.

  Here, the “resonant state” is a state in which the ratio of one period of the surface acoustic wave to the circulation time T required for the surface acoustic wave to make one revolution on the propagation surface 11 is 1 / integer of the circulation time T. is there.

  In the resonance state, as shown in FIG. 3A, when a drive signal is input to the interdigital electrode 13, the rotation time T for one round of the surface acoustic wave is an integral multiple of the vibration period of the surface acoustic wave. Become. For this reason, the interdigital electrode 13 applies an electric field that amplifies the vibration of the surface acoustic wave to the spherical member 12 in the same phase as the surface acoustic wave that has already circulated, so that the output intensity of the surface acoustic wave is maximized. .

  In a state that is not in the resonance state, as shown in FIG. 3B, when the drive signal is input to the interdigital electrode 13, the rotation time T for one round of the surface acoustic wave is equal to the vibration period of the surface acoustic wave. It is not an integer multiple. For this reason, surface acoustic waves having different phases are applied to the surface acoustic waves being circulated by the interdigital electrodes 13, and the surface acoustic waves already being circulated are canceled out. Therefore, the intensity of the surface acoustic wave becomes insufficient, and the phase of the output detection signal becomes unstable in terms of time.

  The resonance adjusting unit 24 is for adjusting the carrier frequency of the high-frequency burst signal to a resonance frequency so that the surface acoustic wave detection signal detected by the output unit 22 is in a resonance state.

  The reason for setting the resonance state is that the propagation state of the surface acoustic wave element (hereinafter also referred to as environmental change) is a propagation state that is easy to reproduce when the frequency response before and after the change of the propagation surface is obtained. is there. A plurality of resonance states exist depending on how many times one period corresponds to the wavelength ratio. If the fluctuation range of the environment is set in advance, the frequency can be uniquely adopted as a specific frequency for the environment.

  Another reason for setting the resonance state is to measure a signal having a stable amplitude with small phase fluctuation. When the measurement is performed in a resonance state, the phase of the output signal is proportional to the time, so that there is a great advantage that the propagation speed of the surface acoustic wave can be obtained from the change in the phase.

  For example, when the temperature rises and the propagation speed of the surface acoustic wave increases, the phase of the output signal becomes irregular with respect to time as shown in FIG. The output time (phase) of the signal must be measured. However, in the resonance state, the output signal is temporally stable as shown in FIG. Therefore, it is not necessary to follow the change in the waveform, and the propagation speed of the surface acoustic wave can be obtained from the change in the phase of the output signal at a specific time.

  The waveform adjustment unit 25 is adjusted so that the difference between the detection phase that is the phase of the detection signal output from the output unit 22 after the adjustment by the resonance adjustment unit 24 and the reference phase stored in the storage unit 23 becomes constant. This is for adjusting the carrier frequency of the high frequency burst signal.

  Specifically, the carrier frequency of the high frequency burst signal is adjusted every 5 ppm of the resonance frequency.

  In addition, the waveform adjustment unit 25 inputs the high frequency burst signal to the multi-circular surface acoustic wave element 10 so that the waveform of the detection signal and the waveform of the reference signal are sequentially matched.

  Then, the resonance frequency is adjusted so that the waveforms after the time corresponding to at least 5000 times the circulation time T are matched. Here, when the propagation surface is a spherical surface, the attenuation rate of the surface acoustic wave accompanying the circulation is small. Therefore, phase detection is possible even when the intensity of the detection signal decreases after a lap time longer than 5000 times the wavelength or the reflected wave generated every time a surface acoustic wave passes through the interdigital electrode increases. It is. The measurement in the resonance state is effective in the phase measurement after the lap time of 5000 times or more has elapsed.

  When the phase difference between the detection signal and the reference signal becomes constant as a result of adjustment by the waveform adjustment unit 25, the calculation unit 26 determines the carrier frequency adjusted by the waveform adjustment unit 25 and the reference frequency stored in the storage unit 23. Is calculated.

  Here, the procedure for obtaining the amount of change in frequency when the phase difference is made constant will be described.

  FIG. 4A shows an example of a result obtained by measuring the difference between the detection phase and the reference phase immediately after applying the driving burst signal. Here, in FIG. 4, the vertical axis indicates the phase difference, and the horizontal axis indicates the elapsed time. That is, the amount of change in frequency when the phase difference is made constant is nothing but the frequency when the state of FIG. 4A is adjusted to the state of FIG. 4B.

  The spherical surface acoustic wave element has a diameter of 3.3 mm and a carrier frequency in the vicinity of 150 MHz (here, 152.1 MHz).

  In FIG. 4A, the phase difference of 110 degrees at time 0 seconds changes to -125 degrees after 100 microseconds.

  In other words, the phase of 180 degrees−110 degrees + (− 125 degrees − (− 180)) degrees = 70 degrees + 55 degrees = 125 degrees has changed between time 0 seconds and 100 μsec.

  Here, the change in time when the phase of the 152.1 MHz signal changes by 125 degrees is the product of the time required for one cycle and the rate of phase change.

In other words,
(Signal period) x (Phase change due to multiple rounds / 360 degrees)
= 1 / (152.1 × 10 ⁶ ) × 125 degrees / 360 degrees. And since this change occurs in 100 microseconds, the rate of change is
(Signal period) x (phase change amount due to multiple rounds / 360 degrees) / (total time required for multiple rounds)
1 / (152.1 × 10 ⁶ ) × 125 degrees / 360 degrees / (100 × 10 ⁻⁶ ). That is, the phase of the surface acoustic wave signal is advanced by this ratio.

  Conversely, if the frequency is lowered by this ratio, the phase change will be canceled out. The amount of change in frequency at this time is calculated as follows.

(Frequency change)
= (Carrier frequency) × {(phase change amount due to multiple rounds / 360 degrees) × (signal period)} / (time required for multiple rounds)
= 152.1 × 10 ⁶ × (70 + 55) / 360 × (1 / (152.1 × 10 ⁶ )) / (100 × 10 ⁻⁶ )
= 3470Hz
It becomes.

  That is, when the carrier frequency is changed by 3470 Hz, the detection phase asymptotically approaches the reference phase in parallel as shown in FIG.

  By the way, when measured before the current measurement, the frequency measured as the resonance frequency was 152.103464 MHz, and the phase value at the time of 100 microseconds was −128.3 degrees. Therefore, there is a difference between the current value of 125 degrees and 3.3 degrees.

Therefore, if the previous equation is further corrected, the required frequency change amount is
152.096634 × 10 ⁶ × (3.3) / 360 × (1 / (152.096634 × 10 ⁶ )) / (100 × 10 ⁶ )
= 9.2Hz
It becomes.

Therefore,
1520966634Hz-9.2Hz = 152096625Hz
It becomes.

  There is a difference of 6839 Hz from the frequency 152103464 MHz of the previous measurement result.

  Thereby, it can be determined that there is a change in propagation velocity of 6839 Hz / 152103464 Hz = about 44 ppm.

  The storage unit 23, the resonance adjustment unit 24, the waveform adjustment unit 25, and the calculation unit 26 can be realized by a hardware configuration, and can also be realized by a combination of a hardware configuration and a software configuration. In the latter case, each function of the software configuration is realized by installing a program obtained in advance from a computer-readable storage medium or a network.

  The high frequency signal source 30 generates a high frequency and outputs it to the input unit 21.

(Operation of Frequency Change Calculation Device 20)
Next, the operation of the frequency variation calculation device 20 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, a high frequency burst signal is input to the interdigital electrode 13 of the multi-round surface acoustic wave element 10 by the input unit 21 (S1). Thereby, a surface acoustic wave is excited on the propagation surface 11 in the multi-circular surface acoustic wave element 10.

  The excited surface acoustic wave is detected by the interdigital electrode 13 and output to the resonance adjustment unit 24 and the waveform adjustment unit 25 via the output unit 22 (S2).

  Next, the carrier frequency is adjusted by the resonance adjusting unit 24 so as to be in a resonance state (S3). Here, when the resonance state is not established, the carrier frequency is changed. Then, this operation is repeated until the detection signal output from the output unit 22 is in a resonance state (S3-No, S4).

  Note that whether or not the resonance state has been reached can also be determined based on the intensity of the detection signal. That is, since the waves strengthen each other in the resonance state, the intensity value rapidly increases.

  Next, when the carrier frequency is adjusted so that the resonance adjustment unit 24 enters a resonance state, the difference between the detection phase of the detection signal output from the output unit 22 and the reference phase stored in advance in the storage unit 23 is constant. The carrier frequency of the high frequency burst signal is adjusted by the waveform adjustment unit 25 (S3-Yes, S5). Here, when the phase difference is not constant, the carrier frequency is changed. Then, this operation is repeated until the difference between the detection phase output by the output unit 22 and the reference phase becomes constant (S5-No, S6).

  Next, when the phase difference between the detected phase and the reference phase becomes constant as a result of adjustment by the waveform adjustment unit 25, the difference between the carrier frequency adjusted by the waveform adjustment unit 25 and the reference frequency stored in the storage unit 23 Is calculated by the calculation unit 26 (S5-Yes, S7).

  As described above, according to the frequency variation calculation device 20 according to the present embodiment, the reference signal data having at least the reference phase and preferably the intensity information of the surface acoustic wave in the resonance state, and the surface acoustic wave. A storage unit 23 for preliminarily storing a reference frequency for exciting the signal, a resonance adjusting unit 24 for adjusting the carrier frequency of the high-frequency burst signal to a resonance frequency, a detection phase and a reference phase that are phases of the detection signal, The waveform adjustment unit 25 for adjusting the carrier frequency of the high-frequency burst signal so that the difference between them is constant with respect to time, and the carrier frequency adjusted by the waveform adjustment unit 25 when the phase difference between them is constant And a calculation unit 26 that calculates a difference between the reference frequency and the reference frequency, the change in the phase is obtained after the resonance state is obtained. Can be suppressed, it is possible to calculate the frequency change in the multi-turn surface acoustic wave element 10 with high precision.

  Note that the frequency change amount calculation method according to the present embodiment is not limited to obtaining a normal resonance frequency (resonance frequency). Even if a resonance state is established using a burst signal, the phase is not completely proportional to the time as long as measurement is performed using the burst signal. Even in such a case, the frequency variation calculation method according to the present embodiment can be used as long as accurate measurement is realized by revealing the resonance state and comparing it with the stored reference phase. Is not excluded.

  Furthermore, according to the present embodiment, the waveform adjustment unit 25 sequentially matches the waveform of the detection signal and the waveform of the reference signal after inputting the high-frequency burst signal, and makes the propagation surface spherical and accompanies the circulation. The attenuation due to wave diffraction is reduced. And since the resonance frequency is adjusted so that the waveform after the time corresponding to at least 5000 times the round time is matched, the phase change due to multiple rounds can be detected with high accuracy.

  Further, according to the present embodiment, the waveform adjustment unit 25 makes the carrier frequency of the high-frequency burst signal variable every 5 ppm of the resonance frequency, so that the waveforms can be matched with high accuracy.

  In addition, according to the present embodiment, the high frequency burst signal has a carrier frequency of 10 MHz or more and is composed of a wave having a circulation time of at least one round. Therefore, even if the intensity of the surface acoustic wave is attenuated by multiple rounds, the phase is increased. Can be determined.

  When the difference between the phase of the detection signal and the reference phase is 360 degrees or more, the laps do not overlap, for example, by comparison with the phase of the signal of the second round. Accordingly, the resonance frequency can be accurately calculated at a time when the number of circulations is large, using phase data at a time when the phase difference does not increase.

  It should be noted that the propagation state change measurement based on the calculation of the resonance frequency and the frequency value using the resonance frequency can be performed with at least two pieces of phase data.

  In addition, the frequency change amount calculation device 20 further includes an environment storage means for storing a characteristic frequency set in advance with respect to an environmental state around the multi-circular surface acoustic wave element and the environmental state, and a calculation A comparison means for comparing the difference frequency calculated by the means with the characteristic frequency stored by the environment storage means, and an environmental state output means for outputting the environmental state stored by the environment storage means as a result of the comparison by the comparison result. It is also possible to create an environmental measurement device. In this case, a change in the environment can be detected from the frequency fluctuation range due to the change in the environment.

<Second Embodiment>
In the second embodiment of the present invention, the input timing of the high frequency burst signal in the input unit 21 is adjusted.

  The input unit 21 inputs the high frequency burst signal to the multi-round surface acoustic wave element 10 over a time that is an integral multiple of the round time T. As a result, a signal having a relatively stable phase can be obtained.

  Here, three patterns of detection signals obtained according to the timing of inputting the high-frequency burst signal will be described.

(1. Short burst not in resonance)
Usually, the surface acoustic wave is slightly reflected by the interdigital electrode 13 formed on the surface of the multi-circular surface acoustic wave element 10. Therefore, the detected signal spreads before and after the time domain.

  That is, when the frequency of the burst signal is not the resonance frequency and the input time is not an integral multiple of the circulation time T, the detection signal output by performing multiple rotations of the multi-circular surface acoustic wave element 10 is a burst signal for each rotation. (See FIG. 6A).

  In this case, as the number of turns increases, the time spreads and interferes with the preceding and following signals (see FIG. 6B).

  That is, when the phase is measured in a region where the number of laps is large, a stable phase value is obtained in the region where the burst signal is observed (Q region in FIG. 6B), but the region where the burst signal is not observed (FIG. 6). In the (P region of (B)), the signal intensity is small and the phase itself is unclear.

  In this case, when the temperature changes, the P region whose phase is unstable moves at the time of the Q region to be observed. Therefore, it becomes impossible to measure the phase change of linear data.

(2. Long burst that is not in resonance)
When the frequency of the burst signal is not the resonance frequency but the input time is an integral multiple of the round-trip time T, the time length of the burst signal is not the resonance frequency, so that the intensity changes due to interference in a region where adjacent signals overlap (FIG. 7). (See (A)). Therefore, the phase is naturally discontinuous in this region (see FIG. 7B).

(3. Burst in resonance state)
In the case of the resonance state, the influence of the reflected component of the surface acoustic wave and the superposition of the surface acoustic wave spread at an earlier time is less than the above-described pattern.

  For example, if the frequency of the burst signal is the resonance frequency and the input time is an integral multiple of the circulation time T, the signal phase has a stable distribution in both the Q region and the P region (see FIG. 8). For this reason, the measured value is stabilized even if the arrival time of the signal is somewhat changed by the temperature or the like.

  If the frequency of the burst signal is the resonance frequency, a signal having a relatively stable phase can be obtained even when the input time is shorter than the circulation time T. As a result, the measurement can be performed accurately.

  As described above, according to the present embodiment, the input unit 21 inputs the high-frequency burst signal over a time that is an integral multiple of the circulation time T, so that it is possible to suppress noise due to interference of the detection signal that has been circulated multiple times.

  In particular, when the number of circulations (ratio of propagation length of surface acoustic wave to wavelength) is large, highly accurate phase detection can be performed.

  For example, when the resolution of surface acoustic wave propagation velocity measurement exceeds 3 ppm and exceeds 5000 times the wavelength, highly accurate phase detection can be performed.

  In addition, in the case of a 45 MHz element using a crystal Z-axis cylinder having a diameter of 1 cm, this effect appears when the number of turns exceeds 20 turns (equivalent to 9500 times). On the other hand, when a 15 MHz element is produced using the same quartz crystal base material, the shape of the burst signal collapses in about 30 rounds (4500 times). This is because even if the propagation length is sufficiently small from the multiple of the wavelength, the influence from the electrode or the like increases every time it circulates, affecting the phase measurement.

  In addition, in the frequency variation calculation device 20 according to the present embodiment, a signal whose signal intensity changes exponentially according to the circulation is a measurement target. Therefore, it is possible to prevent measurement from becoming inaccurate due to a change in the absolute value of the phase in the process of equalizing the intensities of the detection signal and the reference signal.

<Third Embodiment>
FIG. 9 is a schematic diagram showing a configuration of a frequency variation calculation system according to the third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the part same as the part demonstrated in 1st Embodiment, and the overlapping description is abbreviate | omitted. In the following embodiments, duplicate descriptions are omitted in the same manner.

  The multi-circular surface acoustic wave element 10T is used for temperature calibration.

  The input unit 21 includes a modulation circuit 21A, an RF switch 21B, a unidirectional coupler 21C, an RF switch 21D, and an element changeover switch 21E.

  The modulation circuit 21A can modulate the carrier frequency of the high-frequency signal from the high-frequency signal source 30 at 150 MHz and finely adjust the modulated frequency at 1 Hz intervals.

  The RF switch 21B converts the high frequency signal adjusted by the modulation circuit 21A into a burst signal.

  The unidirectional coupler 21C is for preventing the detection signal of the surface acoustic wave from the multi-round surface acoustic wave element 10 from traveling backward.

  The RF switch 21D is a switch that can select whether to connect the unidirectional coupler 21C and the element changeover switch 21E or to connect the unidirectional coupler 21C and the amplifier 22A.

  The element changeover switch 21E is a switch that can select the multi-round surface acoustic wave element 10 or 10T.

  The output unit 22 includes an amplification unit 22A, a modulation circuit 22B, a multiplier 22C, an IF filter 22D, an A / D converter 22E, a multiplier 22F, an I / D 22G, a multiplier 22H, an I / D 22I, a phase calculator 22J, and an intensity. A detector 22K, a low-pass filter 22L, an A / D converter 22M, and an output processing unit 22N are provided.

  Further, the modulation circuit 22B, the multiplier 22C, the IF filter 22D, and the A / D converter 22E can obtain the waveform of the detection signal by heterodyne detection.

  The reason for using heterodyne detection is as follows.

  The measurement of the surface acoustic wave has a very slight phase change rate as a measurement target. For this reason, it is necessary to make the drive signals the same so as not to be affected by the instability between elements and elements.

  In particular, when a wide-band signal is used, it is difficult to remove other noise signals even if a frequency filter that passes only a specific frequency to be observed is used.

  In this case, the phase of a surface acoustic wave signal having a propagation distance of 5000 cycles can be accurately captured only when a burst signal having a duration of one or more rounds in a narrow band is used and detection is performed using a heterodyne detection method. Can do.

  The A / D converter 22E digitizes the intensity of the waveform obtained in the heterodyne detection to obtain a digital intensity value.

  The output processing unit 22N is for outputting signals obtained from the phase calculator 22J and the A / D converter 22M to the resonance adjusting unit 24 and the waveform adjusting unit 25.

  The storage unit 23 stores a digital intensity value obtained by digitizing the intensity of the reference waveform obtained by heterodyne detection.

The waveform adjustment unit 25 adjusts the carrier frequency so that the digital intensity value of the detection signal obtained by the A / D converter 22E matches the digital intensity value of the reference waveform. Thereby, the difference between the detected phase output from the output unit 22 and the reference phase stored in the storage unit 23 can be made constant.

  As described above, in this embodiment, the output unit 22 obtains the waveform of the detection signal by heterodyne detection, digitizes the intensity of the obtained waveform, and stores the intensity of the waveform of the reference signal in the storage unit 23. The digitized digital intensity value is stored, and the waveform adjusting unit 25 resonates the resonance frequency so that the digital intensity value obtained by the A / D converter 22E matches the digital intensity value of the waveform of the reference signal. Adjust. As described above, since the waveform is matched with the digital intensity value, signal processing by a computer can be executed with high accuracy.

<Fourth Embodiment>
FIG. 10 is a schematic diagram showing the configuration of a multi-circular surface acoustic wave device 10S according to the fourth embodiment of the present invention.

  The multi-circular surface acoustic wave element 10 </ b> S includes an interdigital electrode 13 that is installed in a non-contact manner so as to face the propagation surface 11 and excites a surface acoustic wave by applying an electric field to the propagation surface.

  Specifically, an external base material 14 is provided around the spherical member 12, a void region R is provided in the spherical member 12 and the mold base material 14, and the interdigital electrode 13 is formed in the void region R.

  An arrow Z in FIG. 10 indicates the crystal axis Z-axis direction of the crystal, and the propagation direction of the surface acoustic wave excited by the interdigital electrode 13 is a direction perpendicular to the paper surface.

  By the way, when a circulating surface acoustic wave passes through the interdigital electrode, (a) the energy leaks to the electric circuit each time the surface acoustic wave circulates (b) the energy of the surface acoustic wave against the air or water. The energy of the surface acoustic wave is lost due to the reason that the surface acoustic wave is reflected and scattered by the substance on the propagation path.

  Among these, the influence of energy loss (above (c)) due to leakage into the circuit is particularly large.

  On the other hand, when the multi-round surface acoustic wave element 10 of the present embodiment is used, there is an electrical interaction between the spherical member 12 and the interdigital electrode 13, but the mass of the interdigital electrode 13 and the scattering of the surface acoustic wave. The effect of the effect can be eliminated. As a result, adverse effects related to phase measurement can be reduced as much as possible.

  As described above, the multi-circular surface acoustic wave device 10 according to the present embodiment is installed in a non-contact manner so as to face the propagation surface 11 and applies an electric field to the propagation surface 11 to excite surface acoustic waves. With the configuration including the electrode 13, the surface acoustic wave can be propagated to the propagation surface 11 without being affected by the mass of the interdigital electrode 13 or the scattering effect between the interdigital electrode 13 and the surface acoustic wave. Therefore, it is possible to provide the multi-round surface acoustic wave device 10 that can calculate the amount of frequency change with high accuracy.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine a component suitably in different embodiment.

It is a schematic diagram which shows an example of a structure of the frequency variation calculation system which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of a structure of the multiple circulation surface acoustic wave element which concerns on the same embodiment. It is a figure for demonstrating the resonance state which concerns on the same embodiment. It is a figure which shows the change of the phase which concerns on the same embodiment. It is a flowchart for demonstrating operation | movement of the frequency variation calculation apparatus 20 which concerns on the same embodiment. It is a figure which shows the detection signal which concerns on the 2nd Embodiment of this invention. It is a figure which shows the detection signal which concerns on the same embodiment. It is a figure which shows the detection signal which concerns on the same embodiment. It is a schematic diagram which shows an example of a structure of the frequency variation calculation system which concerns on the 3rd Embodiment of this invention. It is a schematic diagram which shows an example of a structure of the multi-around surface acoustic wave element 10 which concerns on the 4th Embodiment of this invention.

Explanation of symbols

      DESCRIPTION OF SYMBOLS 10 ... Multi-around surface acoustic wave element, 11 ... Propagation surface, 12 ... Spherical member, 13 ... Interdigital electrode, 20 ... Frequency change amount calculation apparatus, 21 ... Input part, 21A ... modulation circuit, 21B ... RF switch, 21C ... unidirectional coupler, 21D ... RF switch, 21E ... element selector switch, 22 ... output unit, 22A ... Amplifying section, 22B ... modulation circuit, 22C ... multiplier, 22D ... IF filter, 22E ... A / D converter, 22F ... multiplier, 22G ... I / D, 22H ... Multiplier, 22I ... I / D, 22J ... Phase calculator, 22K ... Intensity detector, 22L ... Low pass filter, 22M ... A / D converter, 22N ... Output processing unit, 23 ... storage unit, 24 ... resonance adjustment unit, 25 · Waveform adjusting section, 26 ... calculator, 30 ... high frequency signal source.

Claims (13)

An elastic surface connected to a multi-surface acoustic wave element that is excited by a surface acoustic wave that circulates around the propagation surface by the input of a high-frequency burst signal having a carrier frequency, and measures the amount of change in the output frequency from the surface acoustic wave element A wave propagation state measuring device,
Input means for inputting the high-frequency burst signal to the multi-round surface acoustic wave element;
After the input, output means for detecting a surface acoustic wave that circulates around the propagation surface and outputs the obtained detection signal;
A reference including a reference phase of the surface acoustic wave in the resonance state with respect to a resonance state in which the ratio of one period in the carrier frequency to the circulation time required for the surface acoustic wave to make one round on the propagation surface is 1 / integer Storage means for preliminarily storing signal data and a reference frequency for exciting the surface acoustic wave;
First adjusting means for adjusting the carrier frequency of the high-frequency burst signal to a resonance frequency so that the detection signal of the surface acoustic wave is in a resonance state;
After the adjustment by the first adjustment unit, the high-frequency burst signal is adjusted so that the difference between the detection phase that is the phase of the detection signal output from the output unit and the reference phase stored in the storage unit is constant. A second adjusting means for adjusting the carrier frequency;
A calculation means for calculating a difference between the carrier frequency adjusted by the second adjustment means and the reference frequency stored in the storage means when the phase difference between the two becomes constant as a result of the adjustment by the second adjustment means; A surface acoustic wave propagation state measuring apparatus comprising: In the surface acoustic wave propagation state measuring apparatus according to claim 1,
The multi-round surface acoustic wave element has a spherical propagation surface,
The second adjusting means includes
The waveform of the detection signal and the waveform of the reference signal are sequentially matched from the time when the number of laps is small after inputting the high-frequency burst signal, and at least after a time corresponding to 5000 times the period of the resonance frequency The surface acoustic wave propagation state measuring apparatus, wherein the resonance frequency is adjusted so as to match the waveforms. In the surface acoustic wave propagation state measuring device according to claim 1 or 2,
2. The surface acoustic wave propagation state measuring apparatus according to claim 1, wherein the high-frequency burst signal has a carrier frequency of 10 MHz or more and is composed of a wave having a circulation time of at least one round. The surface acoustic wave propagation state measuring apparatus according to any one of claims 1 to 3,
The surface acoustic wave propagation state measuring apparatus according to claim 2, wherein the second adjustment means makes the carrier frequency of the high-frequency burst signal variable every 5 ppm of the resonance frequency. The surface acoustic wave propagation state measuring apparatus according to any one of claims 1 to 4,
The surface acoustic wave propagation state measuring apparatus according to claim 1, wherein the input means inputs the high-frequency burst signal over a time that is twice or more as long as the surface acoustic wave makes one round of the propagation surface. An environment change measuring device using the surface acoustic wave propagation state measuring device according to claim 1,
Environmental storage means for storing a characteristic frequency set in advance with respect to an environmental state around the multi-circular surface acoustic wave element and the environmental state in association with each other;
A comparison means for comparing the difference frequency calculated by the calculation means with the characteristic frequency stored by the environment storage means;
An environmental change measuring apparatus comprising: an environmental state output unit that outputs an environmental state stored by the environmental storage unit as a result of comparison by the comparison unit. In the multi-surface acoustic wave device used in the surface acoustic wave propagation state measuring device according to claim 1,
A multi-circular surface acoustic wave device comprising an interdigital electrode that is installed in a non-contact manner facing the propagation surface and applies an electric field to the propagation surface to excite a surface acoustic wave. A surface acoustic wave propagation state measuring method for measuring a change amount of an output frequency from a multi-surface acoustic wave element in which a surface acoustic wave that multi-circulates a propagation surface is excited by input of a high-frequency burst signal having a carrier frequency,
An input step of inputting the high-frequency burst signal to the multi-circular surface acoustic wave element;
After the input, an output step of detecting a surface acoustic wave that circulates around the propagation surface and outputting the obtained detection signal;
A reference including a reference phase of the surface acoustic wave in the resonance state with respect to a resonance state in which a ratio of one period in the carrier frequency occupying in a circulation time required for one round of the surface acoustic wave to circulate on the propagation surface is 1 / integer A storage step for preliminarily storing signal data and a reference frequency for exciting the surface acoustic wave;
A first adjustment step for adjusting the carrier frequency of the high-frequency burst signal to a resonance frequency so that the detection signal of the surface acoustic wave is in a resonance state;
After the adjustment in the first adjustment step, the high-frequency burst signal is adjusted so that the difference between the detection phase, which is the phase of the detection signal output from the output step, and the reference phase stored in the storage step is constant. A second adjustment step for adjusting the carrier frequency;
A calculation step for calculating a difference between the carrier frequency adjusted in the second adjustment step and the reference frequency stored in the storage means when the phase difference between the two becomes constant as a result of the adjustment in the second adjustment step; A surface acoustic wave propagation state measuring method comprising: In the surface acoustic wave propagation state measuring method according to claim 8,
The multi-round surface acoustic wave element has a spherical propagation surface,
The second adjustment step includes
The waveform of the detection signal and the waveform of the reference signal are sequentially matched from the time when the number of laps is small after inputting the high-frequency burst signal, and at least after a time corresponding to 5000 times the period of the resonance frequency A surface acoustic wave propagation state measuring method, wherein the resonance frequency is adjusted so that the waveforms match. In the surface acoustic wave propagation state measuring method according to claim 8 or 9,
2. The surface acoustic wave propagation state measuring method according to claim 1, wherein the high-frequency burst signal has a carrier frequency of 10 MHz or more and is composed of a wave having a circulation time of at least one round. The surface acoustic wave propagation state measurement method according to any one of claims 8 to 10,
In the second adjustment step, the carrier frequency of the high-frequency burst signal is made variable every 5 ppm of the resonance frequency. The surface acoustic wave propagation state measuring method according to any one of claims 8 to 11,
The surface acoustic wave propagation state measuring method characterized in that the input step inputs the high-frequency burst signal over a time that is twice or more the time required for the surface acoustic wave to make one round of the propagation surface. An environmental change measurement method using the surface acoustic wave propagation state measurement method according to claim 8,
An environment storage step for storing the characteristic frequency set in advance with respect to the environmental state around the multi-circular surface acoustic wave element in association with the environmental state;
A comparison step of comparing the frequency of the difference calculated by the calculation step with the characteristic frequency stored by the environment storage step;
An environmental change measurement method comprising: an environmental state output step of outputting the environmental state stored in the environmental storage step as a result of the comparison in the comparison step.

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