WO2011142380A1 - Temperature sensor - Google Patents

Temperature sensor Download PDF

Info

Publication number
WO2011142380A1
WO2011142380A1 PCT/JP2011/060835 JP2011060835W WO2011142380A1 WO 2011142380 A1 WO2011142380 A1 WO 2011142380A1 JP 2011060835 W JP2011060835 W JP 2011060835W WO 2011142380 A1 WO2011142380 A1 WO 2011142380A1
Authority
WO
WIPO (PCT)
Prior art keywords
surface acoustic
acoustic wave
wave resonator
temperature sensor
propagation direction
Prior art date
Application number
PCT/JP2011/060835
Other languages
French (fr)
Japanese (ja)
Inventor
道雄 門田
重夫 伊藤
吉博 伊藤
有里 星野
Original Assignee
株式会社村田製作所
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Priority to JP2012514817A priority Critical patent/JP5527410B2/en
Publication of WO2011142380A1 publication Critical patent/WO2011142380A1/en

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/22—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of acoustic effects
    • G01K11/26—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of acoustic effects of resonant frequencies
    • G01K11/265—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of acoustic effects of resonant frequencies using surface acoustic wave [SAW]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
    • G01K1/14—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations
    • G01K1/143—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations for measuring surface temperatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/20—Clinical contact thermometers for use with humans or animals

Definitions

  • the present invention relates to a temperature sensor for measuring a temperature in a temperature range of ⁇ 20 ° C. to 150 ° C. such as a temperature of a steam gas pipe, a body temperature, and a bath temperature, and more specifically, a plurality of surface acoustic waves.
  • the present invention relates to a temperature sensor that measures temperature based on a difference in resonance characteristics of a resonator.
  • Patent Document 1 discloses a temperature detection device shown in FIG.
  • first and second surface acoustic wave resonators 1003 and 1004 are configured on a quartz substrate 1002.
  • the first and second surface acoustic wave resonators 1003 and 1004 include IDT electrodes and reflectors disposed on both sides of the IDT electrode in the surface acoustic wave propagation direction.
  • a first operational amplifier 1005 is connected to the first surface acoustic wave resonator 1003.
  • a second operational amplifier 1007 is connected to the second surface acoustic wave resonator 1004. Outputs of the first and second surface acoustic wave resonators 1003 and 1004 are given to the detection circuit 1010.
  • FIG. 17 shows a frequency temperature characteristic f1 of the first surface acoustic wave resonator 1003 and a frequency temperature characteristic f2 of the second surface acoustic wave resonator 1004.
  • the frequency temperature characteristics f1 and f2 of the resonance frequency have a shape like a quadratic curve.
  • the resonance frequency difference f2-f1 has a linear relationship with the temperature. Therefore, in Patent Document 1, it is supposed that the temperature can be measured by the resonance frequency difference in a temperature range where the difference of the resonance frequency difference (f2-f1) changes linearly with respect to the temperature.
  • Patent Document 1 also discloses a configuration in which the surface acoustic wave propagation direction of the first surface acoustic wave resonator 1003 and the surface acoustic wave propagation direction of the second surface acoustic wave resonator 1004 are different by 90 °. .
  • the temperature is determined by utilizing the difference between the resonance frequencies of the two surface acoustic wave resonators 1003 and 1004. Therefore, it is described that the temperature can be measured with high accuracy without using an absolute temperature and frequency reference.
  • Non-Patent Document 1 discloses a temperature detection device in which two surface acoustic wave resonators are formed on one quartz substrate.
  • 18 shows the relationship between the temperature in the temperature detection device described in Non-Patent Document 1 and the resonance frequency difference between the two surface acoustic wave resonators
  • FIG. 19 shows the frequency characteristic of the reflection characteristic S11 in the temperature detection device.
  • two IDTs having different propagation directions are formed on a quartz substrate, and the temperature is measured by the difference between the two resonance frequencies as in the case of Patent Document 1. .
  • Patent Document 1 discloses that the surface acoustic wave propagation directions of the two surface acoustic wave resonators 1003 and 1004 formed on one crystal substrate 1002 are different by 90 °, The azimuth is only described as ST cut. That is, Patent Document 1 does not specifically show a configuration capable of measuring temperature with high accuracy in various temperature ranges.
  • Patent Document 1 As described above, in Patent Document 1, as the configuration in which the surface acoustic wave propagation directions of the first surface acoustic wave resonator and the second surface acoustic wave resonator are made different, the propagation angles of the two are made 90 ° different from each other. It is shown. However, when the propagation angle is varied by 90 °, a large quartz substrate must be used. Therefore, downsizing cannot be promoted.
  • Non-Patent Document 1 and Non-Patent Document 2 disclose that the surface acoustic wave propagation directions of two surface acoustic wave resonators formed on one quartz substrate are made different to measure the temperature.
  • the electromechanical coupling coefficient of the surface acoustic wave resonator is in a small range at the Euler angle used. Therefore, the output of the surface acoustic wave resonator cannot be made sufficiently large, and the temperature cannot be measured with high accuracy.
  • An object of the present invention is to use the characteristic difference between the first and second surface acoustic wave resonators to measure a temperature within a temperature range of ⁇ 20 ° C. to 150 ° C. with high accuracy and to reduce the size.
  • An object of the present invention is to provide a temperature sensor capable of achieving
  • a temperature sensor is a temperature sensor for measuring a temperature within a range of ⁇ 20 ° C. to 150 ° C., and includes a quartz substrate and a first surface acoustic wave resonator formed on the quartz substrate. And a second surface acoustic wave resonator formed on the quartz substrate.
  • TCF the frequency temperature coefficient at ⁇ 20 ° C. to 150 ° C. of the first and second surface acoustic wave resonators
  • the absolute value of the TCF of the child is 10 ppm / ° C.
  • the TCF of the first surface acoustic wave resonator and the TCF of the second surface acoustic wave resonator are different, and the first elasticity
  • the difference D (degree) between the propagation direction of the surface acoustic wave in the surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less
  • the first elastic surface When the electromechanical coupling coefficient of the wave resonator is k 2 (1) and the electromechanical coupling coefficient of the second resonator is k 2 (2), k 2 (1) ⁇ 0.0002 and k 2 ( 2) ⁇ 0.0002.
  • TCF V ⁇ 1 (35 ° C.) ⁇ [(V (150 ° C.) ⁇ V ( ⁇ 20 ° C.)) / 170 ° C.] ⁇ LEC Formula (1)
  • V represents the speed of sound (m / sec)
  • V ⁇ 1 (35 ° C.) means the reciprocal of the sound speed at 35 ° C.
  • V (150 ° C.) and V ( ⁇ 20 ° C.) Represents the sound velocity (m / sec) at 150 ° C. and ⁇ 20 ° C., respectively
  • LEC represents the linear expansion coefficient (unit: 1 / ° C.) of the quartz substrate.
  • a Rayleigh wave is used as the surface acoustic wave
  • the first and second surface acoustic wave resonators are used.
  • the first Euler angle and the second Euler angle when the Euler angles of the quartz substrate in FIG. 1 are the first Euler angles ( ⁇ , ⁇ , ⁇ 1) and the second Euler angles ( ⁇ , ⁇ , ⁇ 2), respectively. Satisfy one of the combinations shown in Tables 1 to 3 below.
  • a leaky surface acoustic wave is used as the surface acoustic wave, and the first and second surface acoustic waves are used.
  • the Euler angles of the quartz substrate in the wave resonator are the first Euler angles ( ⁇ , ⁇ , ⁇ 1) and the second Euler angles ( ⁇ , ⁇ , ⁇ 2), respectively, the first Euler angles and the second Euler angles
  • the Euler angles satisfy any combination shown in Table 4 below.
  • a Rayleigh wave is used as a surface acoustic wave in the first surface acoustic wave resonator, and a surface acoustic wave is used in the second surface acoustic wave resonator.
  • the Euler angle of the quartz crystal substrate is in one of the ranges shown in Table 5 below.
  • the first surface acoustic wave resonator includes a first IDT electrode and reflectors arranged on both sides of the first IDT electrode in the surface acoustic wave propagation direction.
  • the second surface acoustic wave resonator includes an IDT electrode and reflectors disposed on both sides of the surface acoustic wave propagation direction of the IDT electrode.
  • one IDT electrode is disposed on the quartz substrate and both sides of the IDT electrode, and a plurality of each is provided.
  • First and second reflectors having electrode fingers, and the first surface acoustic wave resonator using Rayleigh waves by the IDT electrode and the first and second reflectors;
  • the second surface acoustic wave resonator using the leaky surface acoustic wave is configured.
  • the IDT electrode has first and second comb electrodes arranged so that mutual electrode fingers are inserted.
  • the lines connecting the tips of the electrode fingers in the first and second comb electrodes are defined as first and second virtual straight lines, and the first and second virtual straight lines are parallel to the Rayleigh wave propagation direction.
  • the temperature sensor has a third imaginary straight line passing through the intersection of the first imaginary straight line and the outermost electrode finger of the IDT electrode on the second reflector side and extending parallel to the LSAW propagation direction.
  • a straight line extending through the intersection of the IDT electrode with the outermost electrode finger on the first reflector side and extending parallel to the LSAW propagation direction is a fourth virtual straight line, one end of the electrode finger of the first reflector is the first virtual line.
  • the plurality of electrode fingers of the first and second reflectors can reflect the Rayleigh wave and the leaky surface acoustic wave, respectively.
  • the first and second surface acoustic wave resonators can be constituted by one IDT electrode and the first and second reflectors. Therefore, the temperature sensor can be further reduced in size.
  • the extending direction of the electrode fingers of the first and second reflectors is parallel to the extending direction of the electrode fingers of the IDT electrode, and the crossing of the electrode fingers of the IDT electrode is performed.
  • the width is W (unit is m)
  • the distance between the first and second reflectors and the outermost electrode fingers of the IDT electrode is L (unit is m)
  • the first and second reflectors are
  • H unit is m
  • a resonance frequency F1 of the first surface acoustic wave resonator and the second surface acoustic wave resonator in a temperature range in which the temperature sensor is used is used. It is preferable that the resonance frequency F2 is configured so as to be more than ⁇ F shown in the equation (2).
  • F1h is a higher frequency among the frequencies that are 1 / ⁇ 2 of the amplitude intensity in F1
  • F1l is a frequency that is 1 / ⁇ 2 of the amplitude intensity in F1.
  • the lower frequency is shown.
  • F2h is a higher frequency among the frequencies that are 1 / ⁇ 2 of the amplitude intensity in F2
  • F2l is a lower frequency among the frequencies that are 1 / ⁇ 2 of the amplitude intensity in F2. Indicates the frequency.
  • the absolute value of the TCF of the first and second surface acoustic wave resonators is 10 ppm / ° C. or more, the polarity of the TCF of the first surface acoustic wave resonator, and the second elastic wave Since the polarity of the TCF of the surface acoustic wave resonator is different, the difference ⁇ TCF between the TCF of the first surface acoustic wave resonator and the TCF of the second surface acoustic wave resonator is as large as 20 ppm / ° C. or more. That is, since the change of the resonance frequency difference with temperature is large, the temperature can be measured with high accuracy in the temperature range of ⁇ 20 ° C. to 150 ° C.
  • the temperature can be measured with high accuracy.
  • the absolute value of one TCF is less than 10 ppm / ° C., for example, close to 0 ppm / ° C., the amount of frequency change due to temperature becomes less than the frequency reading accuracy. Therefore, the temperature cannot be measured.
  • ⁇ TCF is as large as 20 ppm / ° C. or more
  • the absolute value of TCF of the first and second surface acoustic wave resonators is 10 ppm / ° C. or more, and both polarities are different. Yes. Therefore, the temperature can be measured with high accuracy at a temperature of ⁇ 20 ° C. to 150 ° C. as described above.
  • the temperature sensor can be miniaturized.
  • the frequency temperature coefficient TCF of the surface acoustic wave resonator using the Euler angle quartz crystal substrates shown in Tables 1 to 3, 4 and 5 is linear with respect to the temperature in the temperature range of ⁇ 20 ° C. to 150 ° C. Have the same relationship. Accordingly, it is possible to measure the temperature with high accuracy in the temperature range of -20 ° C to 150 ° C.
  • the temperature sensor of the present invention is preferably used for measuring temperatures belonging to a temperature range of ⁇ 20 ° C. to 150 ° C. such as the temperature of the steam gas pipe, the body temperature, and the temperature of the bath.
  • the temperature is measured using the difference between the temperature characteristics of the resonance frequency of the first surface acoustic wave resonator and the resonance frequency of the second surface acoustic wave resonator. Errors due to manufacturing variations are less likely to occur. Further, the absolute temperature of the object to be measured can be reliably measured.
  • FIG. 1 is a schematic plan view for explaining a temperature sensor according to a first embodiment of the present invention.
  • FIG. 2 is a diagram illustrating a resonance frequency temperature characteristic of the first surface acoustic wave resonator and a resonance frequency temperature characteristic of the second surface acoustic wave resonator in the temperature sensor of the first embodiment.
  • FIG. 3 is a diagram showing the relationship between the temperature and the resonance frequency difference ⁇ f of the first and second surface acoustic wave resonators in the temperature sensor of the first embodiment.
  • FIG. 1 is a schematic plan view for explaining a temperature sensor according to a first embodiment of the present invention.
  • FIG. 2 is a diagram illustrating a resonance frequency temperature characteristic of the first surface acoustic wave resonator and a resonance frequency temperature characteristic of the second surface acoustic wave resonator in the temperature sensor of the first embodiment.
  • FIG. 3 is a diagram showing the relationship between the temperature and the resonance frequency difference ⁇ f of the first and second surface
  • FIG. 4 shows the relationship between the TCF and the electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the Rayleigh wave and the Euler angle ⁇ when a quartz substrate with Euler angles (0 °, 45 °, ⁇ ) is used. It is a figure which shows a relationship.
  • FIG. 5 is a diagram showing the relationship between ⁇ and the propagation direction [ ⁇ + PFA] in a surface acoustic wave resonator using a Rayleigh wave when using a quartz substrate with Euler angles (0 °, 45 °, ⁇ ). .
  • FIG. 6 shows the TCF and electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the leaky surface acoustic wave when using the Euler angle (0 °, 10 °, ⁇ ) quartz substrate, and the Euler angle ⁇ . It is a figure which shows the relationship.
  • FIG. 7 is a diagram showing the relationship between ⁇ and the propagation direction [ ⁇ + PFA] in a surface acoustic wave resonator using a leaky surface acoustic wave when a Euler angle (0 °, 10 °, ⁇ ) quartz substrate is used. It is.
  • FIG. 8 is a schematic plan view of a temperature sensor according to another modification of the first embodiment of the present invention.
  • FIG. 8 is a schematic plan view of a temperature sensor according to another modification of the first embodiment of the present invention.
  • FIG. 9A is a schematic plan view of a temperature sensor according to the second embodiment of the present invention
  • FIG. 9B is a schematic plan view for explaining a preferred structure thereof.
  • FIG. 10 shows the relationship between the TCF and the electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the Rayleigh wave and the Euler angle ⁇ when a quartz substrate with Euler angles (0 °, 35 °, ⁇ ) is used. It is a figure which shows a relationship.
  • FIG. 10 shows the relationship between the TCF and the electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the Rayleigh wave and the Euler angle ⁇ when a quartz substrate with Euler angles (0 °, 35 °, ⁇ ) is used. It is a figure which shows a relationship.
  • FIG. 10 shows the relationship between the TCF and the electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the Rayleigh wave and the Euler angle ⁇ when
  • FIG. 11 is a diagram showing the relationship between ⁇ and the propagation direction [ ⁇ + PFA] in a surface acoustic wave resonator using a leaky surface acoustic wave when a quartz substrate with Euler angles (0 °, 35 °, ⁇ ) is used. It is.
  • FIG. 12 is a diagram showing a relationship between ⁇ and propagation directions [ ⁇ + PFA] of Rayleigh waves and leaky surface acoustic waves in a surface acoustic wave resonator when a quartz substrate with Euler angles (0 °, 35 °, ⁇ ) is used. It is.
  • FIG. 12 is a diagram showing a relationship between ⁇ and propagation directions [ ⁇ + PFA] of Rayleigh waves and leaky surface acoustic waves in a surface acoustic wave resonator when a quartz substrate with Euler angles (0 °, 35 °, ⁇ ) is used. It is.
  • FIG. 12 is a diagram showing a relationship between ⁇ and propag
  • FIG. 13 shows the relationship between the reflection characteristic S11 of the first surface acoustic wave resonator and the frequency in the temperature sensor of the embodiment of the present invention, the frequency F1 of the first surface acoustic wave resonator, and the second elasticity. It is a figure which shows the example in which the frequency F2 of a surface wave resonator appears as a minimum value.
  • FIG. 14 is a diagram showing the relationship between the reflection characteristic S11 of the first and second surface acoustic wave resonators and the frequency in the temperature sensor according to the embodiment of the present invention, and the first and second frequencies F1 and F2 are shown.
  • FIG. 6 is a diagram illustrating an example in which the second frequency F2 is close and cannot be detected as a minimum value.
  • FIG. 15 is a diagram for explaining a method of detecting the first frequency F1 and the second frequency F2 as minimum values in the frequency characteristics of the first surface acoustic wave resonator and the second surface acoustic wave resonator S11.
  • FIG. 16 is a schematic configuration diagram illustrating an example of a conventional temperature detection device.
  • FIG. 17 is a diagram for explaining a temperature measurement principle in a conventional temperature detection apparatus.
  • FIG. 18 is a diagram illustrating a relationship between a temperature in a conventional temperature detection device and a resonance frequency difference between two surface acoustic wave resonators.
  • FIG. 19 is a diagram showing the frequency characteristic of the reflection characteristic S11 in the conventional temperature detection device.
  • FIG. 1 is a schematic plan view of a temperature sensor according to the first embodiment of the present invention.
  • the temperature sensor 1 has a quartz substrate 2. On the quartz substrate 2, a first surface acoustic wave resonator 3 and a second surface acoustic wave resonator 4 are formed. In the present embodiment, Rayleigh waves are excited in the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4, and the resonance characteristics of the Rayleigh waves are used.
  • the first surface acoustic wave resonator 3 includes a first IDT electrode 5 and reflectors 6 and 7 disposed on both sides of the first IDT electrode 5 in the surface acoustic wave propagation direction.
  • the second surface acoustic wave resonator 4 includes an IDT electrode 8 and reflectors 9 and 10 disposed on both sides of the IDT electrode 8 in the surface acoustic wave propagation direction.
  • the IDT electrodes 5 and 8 each have a pair of bus bars 5b, 5c, 8b and 8c.
  • the reflectors 6, 7, 9, and 10 also have a pair of bus bars 6b, 6c, 7b, 7c, 9b, 9c, 10b, and 10c.
  • the first and second surface acoustic wave resonators 3 and 4 are one-port surface acoustic wave resonators.
  • the first IDT electrode 5, the reflectors 6 and 7, the second IDT electrode 8 and the reflectors 9 and 10 are made of an appropriate metal or alloy.
  • Al is used as the metal or alloy.
  • the surface acoustic wave propagation direction A1 of the first surface acoustic wave resonator 3 and the surface acoustic wave propagation direction A2 of the second surface acoustic wave resonator 4 are different as shown in the figure.
  • the first Euler angles ( ⁇ , ⁇ , ⁇ 1) of the first surface acoustic wave resonator 3 are (0 °, 45 °, 5 °).
  • the Euler angle ⁇ indicates the propagation direction with respect to the X axis (see FIG. 1) of the quartz substrate.
  • the surface acoustic wave propagation direction A1 forms an angle of 13.0 ° with respect to the first Euler angle ⁇ 1, and the IDT electrode 5 and the reflectors 6, 7 is arranged.
  • the first IDT electrode 5 in order to realize such a surface acoustic wave propagation direction A1, in the first IDT electrode 5, a portion where a plurality of electrode fingers are interleaved is formed in a parallelogram shape.
  • the reflectors 6 and 7 are also substantially parallelogram shaped. And the reflectors 6 and 7 are arrange
  • the second Euler angles ( ⁇ , ⁇ , ⁇ 2) of the second surface acoustic wave resonator 4 are (0 °, 45 °, 35 °).
  • a portion where a plurality of electrode fingers are interleaved is formed in a parallelogram shape.
  • the reflectors 9 and 10 are also substantially parallelogram shaped. And the reflectors 9 and 10 are arrange
  • transmission direction A2 may be reflected.
  • the absolute value of the frequency temperature coefficient TCF at ⁇ 20 ° C. to 150 ° C. of the first surface acoustic wave resonator 3 is 10 ppm / ° C. or more, and the first surface acoustic wave resonator.
  • the TCF of the second surface acoustic wave resonator 4 are different in polarity. Therefore, as is clear from the experimental examples described later, it is possible to measure a temperature in the range of ⁇ 20 ° C. to 150 ° C. with high accuracy. Further, since the resonance frequency difference between the surface acoustic wave resonators 3 and 4 is used, it is difficult to be affected by manufacturing variations. In addition, since the surface acoustic wave resonators 3 and 4 are arranged as described above, the size can be reduced. This will be described more specifically below.
  • the TCF is expressed by the following formula (1).
  • TCF V ⁇ 1 (35 ° C.) ⁇ [(V (150 ° C.) ⁇ V ( ⁇ 20 ° C.)) / 170 ° C.] ⁇ LEC Formula (1)
  • V represents the speed of sound (m / sec)
  • V ⁇ 1 (35 ° C.) means the reciprocal of the sound speed at 35 ° C.
  • V (150 ° C.) and V ( ⁇ 20 ° C.) Represents the sound velocity (m / sec) at 150 ° C. and ⁇ 20 ° C., respectively
  • LEC represents the linear expansion coefficient (unit: 1 / ° C.) of the quartz substrate.
  • FIG. 2 is a diagram showing temperature characteristics of the resonance frequencies of the first and second surface acoustic wave resonators 3 and 4.
  • the resonance frequencies of the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 have linearity in the temperature range of ⁇ 20 ° C. to 150 ° C.
  • the resonance frequency increases as the temperature increases. That is, TCF is a positive value in the above temperature range.
  • the second surface acoustic wave resonator 4 the TCF has a negative value in the temperature range shown in FIG. Accordingly, the TCF polarities of the first and second surface acoustic wave resonators 3 and 4 are different in the temperature range of ⁇ 20 ° C. to 150 ° C. described above.
  • the temperature can be detected by obtaining the resonance frequency difference ⁇ f between the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4.
  • the resonance frequency difference between the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 formed on the same quartz crystal substrate 2 is calculated. Use to detect temperature.
  • the temperature characteristic of the resonance frequency of one surface acoustic wave resonator is used, the temperature as a reference fluctuates due to manufacturing variations, and thus the temperature cannot be detected accurately.
  • the temperature sensor 1 of the present embodiment the temperature is detected based on the resonance frequency difference between the first and second surface acoustic wave resonators 3 and 4, so that an error due to manufacturing variations hardly occurs. Therefore, the temperature can be detected accurately.
  • the installation space for the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 can be reduced. Therefore, the temperature sensor 1 can be downsized.
  • the first Euler angle of the first surface acoustic wave resonator 3 is (0 °, 45 °, 5 °)
  • the second Euler angle in the second surface acoustic wave resonator 4 is (0
  • the absolute values of the TCF of the first surface acoustic wave resonator 3 and the TCF of the second surface acoustic wave resonator 4 are 10 ppm / ° C. or more. That is, the difference between the two TCFs can be 20 ppm / ° C. or more.
  • ⁇ 35 °
  • PFA degree of propagation direction
  • the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or more.
  • the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less. Clarify the combination.
  • the surface wave propagation direction is 18.0 °
  • the second ⁇ expressed by the equation (4).
  • the surface wave propagation direction is 31.5 °.
  • the difference D (degree) in the propagation direction is 13.5 °, and thus the combination satisfies 50 ° or less.
  • the surface wave propagation direction is 18.0 °
  • the second expressed by the equation (4) From the range of ⁇ of (0 °, 45 °, 85 °), the surface wave propagation direction is 80.1 °.
  • the difference D (degree) in the propagation direction is 62.1 °, and therefore the combination does not satisfy 50 ° or less.
  • the Rayleigh wave TCF (ppm / ° C.), the electromechanical coupling coefficient k 2, and the power flow angle PFA (degrees) of the surface acoustic wave resonators having various Euler angles were investigated.
  • the absolute value of TCF is 10 ppm / ° C.
  • the measurement accuracy of a circuit that measures the resonance frequency of this type of surface acoustic wave resonator is about 1 ppm.
  • FIG. 6 shows that the first and second ⁇ combinations have an absolute value of TCF of 10 ppm / ° C. or more, both TCF polarities are different, and the electromechanical coupling coefficient k 2 is 0.0002 or more. Can be expressed by a combination of Formula (5) and Formula (6).
  • the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or more.
  • the combination which becomes is also included. Therefore, from FIG. 7, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less. Clarify the combination.
  • the surface wave propagation direction is 59.2 °
  • the second ⁇ expressed by the equation (6) From the range of (0 °, 10 °, 80 °), the surface wave propagation direction is 64.5 °.
  • the difference D (degree) in the propagation direction is 5.3 °, and therefore the combination satisfies 50 ° or less.
  • the propagation direction difference D (degrees) is confirmed in all the combinations of the expressions (5) and (6), in this case, for all the ranges expressed by the expressions (5) and (6), It turns out that it becomes 50 degrees or less.
  • TCF ppm / ° C.
  • electromechanical coupling coefficient k 2 electromechanical coupling coefficient k 2
  • power flow angle PFA degree
  • the first A combination was selected in which the difference D (degree) between the propagation direction of the surface acoustic wave in the surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator was 50 ° or less.
  • the results are shown in Table 9.
  • FIG. 8 is a schematic plan view illustrating another modification of the temperature sensor according to the first embodiment.
  • the first and second surface acoustic wave resonators 3 and 4 shown in FIG. 1 are electrically connected and integrated by a connection electrode finger 32. That is, the second bus bar 8c of the IDT electrode 8 shown in FIG. 1, the second bus bars 9c and 10c of the reflectors 9 and 10, and the first bus bar of the IDT electrode 5 of the second surface acoustic wave resonator 4 are shown. 5b and the first bus bars 6b and 7b of the reflectors 6 and 7 are omitted.
  • the electrode finger connected to the second bus bar 8 c of the IDT electrode 8 and the electrode finger connected to the first bus bar 5 b of the IDT electrode 5 are electrically connected by the connection electrode finger portion 32. It is connected.
  • the electrode fingers connected to the omitted bus bar are electrically connected by the connection electrode finger portions 32.
  • the first and second surface acoustic wave resonators in the present invention may be integrated using a plurality of connection electrode fingers 32.
  • the Rayleigh wave excited in the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 is used.
  • a leaky surface acoustic wave excited by the first and second surface acoustic wave resonators 3 and 4 may be used.
  • FIG. 9A is a schematic plan view showing a temperature sensor according to the second embodiment of the present invention.
  • the temperature sensor 41 has a quartz substrate 42.
  • the Euler angles of the quartz substrate 42 are (0 °, 35 °, ⁇ ).
  • a surface acoustic wave resonator 43 is formed on the quartz substrate 42.
  • the surface acoustic wave resonator 43 includes one IDT electrode 44 and reflectors 45 and 46 disposed on both sides of the IDT electrode 44. That is, one 1-port surface acoustic wave resonator including one IDT electrode 44 and reflectors 45 and 46 disposed on both sides of the IDT electrode 44 is formed.
  • the first and second surface acoustic wave resonators of the present invention are constituted by one surface acoustic wave resonator.
  • Rayleigh waves and leaky surface acoustic waves are used among the surface acoustic waves excited by the IDT electrode 44. That is, two surface acoustic waves excited by one IDT electrode 44 are used.
  • the Euler angles of the surface acoustic wave resonators 43 are (0 °, 35 °, 30 °).
  • the resonance characteristic due to the Rayleigh wave and the resonance characteristic due to the leaky surface acoustic wave can be used.
  • bus bars 44a and 44b move to the X-axis direction side from the reflector 45 side toward the reflector 46 side. Accordingly, the Rayleigh wave and the leaky surface acoustic wave can be surely excited.
  • the reflectors 45 and 46 are configured to reflect the Rayleigh wave and the leaky surface acoustic wave having different propagation directions.
  • the length of the electrode finger far from the IDT electrode 44 is made longer than the size of the electrode finger positioned on the IDT electrode 44 side. This makes it possible to reliably reflect Rayleigh waves and leaky surface acoustic waves having different propagation directions. Therefore, the reflector 45 has a trapezoidal shape with a plurality of electrode fingers and bus bars 45a and 45b, with the IDT electrode 44 side as an upper base and the opposite side as a lower base.
  • the reflector 46 is configured in the same manner as the reflector 45.
  • the temperature sensor 41 As in the temperature sensor 41, two surface acoustic waves having different propagation directions may be excited by one IDT electrode 44. In this case, the temperature sensor 41 can be further reduced in size.
  • the TCF at the first Euler angles (0 °, 35 °, 30 °) when Rayleigh waves are used is ⁇ 16.8 ppm / ° C. as shown in FIG. Is 10 ppm / ° C. or higher.
  • the second Euler angle is also (0 °, 35 °, 30 °), but since the leaky surface acoustic wave is used, the TCF is 37.8 ppm / ° C. as shown in FIG. And its absolute value is greater than 10 ppm / ° C.
  • the first Euler angles (0 °, 35 °, 30 °) TCF by Rayleigh waves, and the second Euler angles (0 °, 35 °, 30 °) TCF using leaky surface acoustic waves Are different in polarity as described above. Therefore, the difference between the two TCFs is 54.6 ppm / ° C., and in this embodiment, a temperature of ⁇ 20 ° C. to 150 ° C. can be measured with high accuracy.
  • the electromechanical coupling coefficient k 2 of the Rayleigh wave is 0.00160
  • the electromechanical coupling coefficient k 2 of the leaky surface acoustic wave is 0.00161. Therefore, an output sufficiently larger than that of the temperature sensor 41 can be taken out.
  • the Rayleigh wave and the leaky surface acoustic wave are excited by one IDT electrode 44 as described above.
  • the Euler angles may be selected so that the absolute values of TCFs of Rayleigh waves and leaky surface acoustic waves excited by one IDT electrode 44 are 10 ppm / ° C. or more and the polarities of the two are different. That is, it is not limited to the Euler angles (0 °, 35 °, 30 °) in the case of the second embodiment.
  • Such Rayleigh wave and the Euler angles of the leaky surface acoustic wave will be described with reference TCF, the electromechanical coupling factor k 2 and PFA below to FIGS. 10 to 12.
  • Figure 10 is Euler angles (0 °, 35 °, 30 °) of the Rayleigh wave TCF and (ppm / ° C.) changes to the electromechanical coupling coefficient k 2 [psi shown as the first surface acoustic wave resonator.
  • FIG. 11 also shows changes in TCF (ppm / ° C.) of the leaky surface acoustic wave having Euler angles (0 °, 35 °, 30 °) and the electromechanical coupling coefficient k 2 with respect to ⁇ as the second surface acoustic wave resonator.
  • the absolute values of TCF of Rayleigh wave and leaky surface acoustic wave are both 10 ppm / ° C. or more, the polarities are different from each other, and the electromechanical coupling coefficient k 2 is both 0.0002 or more.
  • ⁇ can be expressed by Expression (7), Expression (8), and Expression (9).
  • the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or more. It is also included. Accordingly, from FIG. 12, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less. Clarify when.
  • the horizontal axis represents ⁇ (degrees)
  • the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator is 4.1 °.
  • the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 29.4 °.
  • the difference D (degree) in the propagation direction is 25.3 °, which satisfies 50 ° or less.
  • the first ⁇ was selected such that the difference D (degree) between the propagation direction of the surface acoustic wave in the surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator was 50 ° or less.
  • the results are shown in Table 10.
  • the first and second reflectors 45 and 46 are provided so as to reflect the Rayleigh wave and the leaky surface acoustic wave.
  • a plurality of electrode fingers whose one ends are connected to the bus bar 44b of the IDT electrode 44 are defined as first electrode fingers.
  • a straight line connecting the tips of the plurality of first electrode fingers is defined as a first virtual straight line W1.
  • a plurality of electrode fingers connected to the bus bar 44a are defined as second electrode fingers.
  • a straight line connecting the tips of the plurality of second electrode fingers is defined as a second virtual straight line W2.
  • the propagation direction of the Rayleigh wave is the direction in which the first and second virtual straight lines W1, W2 extend. That is, the Rayleigh wave propagates through a region surrounded by the first virtual straight line W1 and the second virtual straight line W2. Accordingly, the first and second reflectors 45 and 46 have a plurality of electrode fingers so that there is a region surrounded by the first and second virtual straight lines W1 and W2. 1 and 2nd reflectors 45 and 46 are preferably provided.
  • a straight line passing through the intersection of the first virtual straight line W1 and the outermost electrode finger on the second reflector 46 side of the IDT electrode 44 and extending in parallel with the leaky surface acoustic wave propagation direction is defined as a third virtual straight line W3.
  • a straight line passing through the intersection of the second virtual straight line W2 and the outermost electrode finger on the first reflector 45 side of the IDT electrode 44 and extending in parallel with the leaky surface acoustic wave propagation direction is defined as a fourth virtual straight line W4.
  • the leaky surface acoustic wave propagation region surrounded by the third virtual straight line W3 and the fourth virtual straight line W4 is used as the first and second reflectors 45 and 46. It is desirable to be located at the electrode finger crossing portion. Therefore, it is desirable to provide the first and second reflectors 45 and 46 in this way.
  • both the Rayleigh wave and the leaky surface acoustic wave can be efficiently reflected. Therefore, the Q of the resonator can be further increased.
  • the first and second reflectors are provided so as to reflect the Rayleigh wave and the leaky surface acoustic wave.
  • the extending direction of the electrode finger in the reflector is parallel to the extending direction of the electrode finger of the IDT electrode and satisfies the following formula H> W + L ⁇ TandD.
  • W unit: m
  • L is the center-to-center spacing (unit: m) between the outermost electrode fingers of the reflector and the IDT electrode.
  • H indicates the length of the electrode fingers of the first and second reflectors.
  • D is the difference (in degrees) between the propagation direction of the Rayleigh wave and the propagation direction of the leaky surface acoustic wave.
  • the combination of the first and second Euler angles is preferably the combination of Tables 6 to 8, Table 9 or Table 10 described above.
  • ⁇ and ⁇ have a width in the range of ⁇ 3 °, for example, 0 ° ⁇ 3 ° or 40 ° ⁇ 3 °.
  • the absolute value of TCF is set to approximately 10 ppm / ° C. or more, as in the above-described embodiment, The polarities of the TCF at the first and second Euler angles can be made different. This will be described using an example in which a Rayleigh wave having an Euler angle of (0 °, 45 °, 0 °) and an Euler angle of (0 °, 45 °, 5 °) is used.
  • Tables 11 and 12 show the relationship between ⁇ and TCF when Rayleigh waves are used, respectively, when Euler angles (0 °, ⁇ , 0 °) or ((0 °, ⁇ , 5 °)) are used. Tables 11 and 12 also show TCF change values when ⁇ is ⁇ -3 ° or ⁇ + 3 °.
  • Table 13 shows the relationship between ⁇ and TCF when a leaky surface acoustic wave is used and the Euler angles are (0 °, ⁇ , 30 °). Table 13 also shows the change in TCF when ⁇ is ⁇ -3 ° or ⁇ + 3 °.
  • Tables 14 and 15 show the case where leaky surface acoustic waves are used, and ⁇ and TCF when the Euler angles are (0 °, ⁇ , 75 °) or (0 °, ⁇ , 80 °). The relationship is shown. Tables 14 and 15 also show TCF change values when ⁇ is ⁇ -3 ° or ⁇ + 3 °.
  • the value of ⁇ may fluctuate ⁇ 3 ° in the same manner even when a leaky surface acoustic wave is used.
  • the absolute value of TCF can be made 10 ppm / ° C. or more in the same manner as described above.
  • the temperature sensor measures the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator.
  • the frequency of the surface acoustic wave resonator is detected as the minimum value of the reflection characteristic (S11) of the resonator.
  • FIG. 13 shows the frequency dependence of the reflection characteristic (S11) of the resonator shown in FIG. If the temperature in this case is T1, the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator is sufficiently large at the temperature T1. Therefore, it is possible to detect the frequencies F1 and F2 of the respective resonators as the minimum values of the respective reflection characteristics (S11).
  • FIG. 14 is a diagram showing the reflection characteristics when the temperature cannot be measured.
  • the reflection characteristic S11 is as shown in FIG.
  • the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator is reduced.
  • FIG. 14 shows a case where it is impossible to detect the frequencies F1 and F2 of the first and second resonators as the minimum value of the reflection characteristic (S11).
  • the frequency F1 of the first surface acoustic wave resonator can be specified, but the frequency F2 of the second surface acoustic wave resonator has no minimum value and cannot be specified.
  • the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator cannot be measured, that is, the temperature cannot be measured. Therefore, in the temperature range in which the temperature sensor is used, for example, in the range of 30 ° C. to 45 ° C.
  • the frequency F1 of the first surface acoustic wave resonator and the second surface acoustic wave resonator are It is necessary to sufficiently increase the frequency difference of the frequency F2. For example, it is necessary to make the electrode finger pitch of the first surface acoustic wave resonator different from the electrode finger pitch of the second surface acoustic wave resonator so that the difference between the frequency F1 and the frequency F2 is sufficiently large. .
  • the detection circuit becomes complicated. Therefore, it is desirable that the frequency difference between the frequency F1 and the frequency F2 be equal to or greater than ⁇ F represented by the equation (2). Thereby, the detection circuit is not complicated, and the frequency difference between the frequency F1 and the frequency F2 can be sufficiently increased. Therefore, the frequencies F1 and F2 can be detected as the minimum value of the reflection characteristics (S11) of the first and second surface acoustic wave resonators. As a result, the temperature can be measured with high accuracy.
  • F1h is the higher frequency of the two frequencies that are 1 / ⁇ 2 of the intensity in F1
  • F1l is the two frequencies that are 1 / ⁇ 2 of the intensity in F1.
  • the higher frequency is shown.
  • F2h is the higher frequency of the two frequencies that are 1 / ⁇ 2 of the intensity in F2
  • F2l is the higher of the two frequencies that are 1 / ⁇ 2 of the intensity in F2.
  • each coefficient 1/5 on the right side of Equation (2) is a value obtained experimentally.
  • FIG. 15 illustrates these relationships.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

Provided is a temperature sensor which can measure with high accuracy temperatures in the temperature range from -20°C to 150°C and which achieves a compact form. In a temperature sensor (1), a first surface acoustic wave resonator (3) and a second surface acoustic wave resonator (4) are formed on a crystal substrate (2). When the frequency-temperature coefficient in -20°C to 150°C for the first and second surface acoustic wave resonators (3, 4) is set as TCF, the absolute values of the TCFs for the first and second surface acoustic wave resonators (3, 4) are 10 ppm/°C or greater, and the polarities of the TCF of the first surface acoustic wave resonator (3) and the TCF of the second surface acoustic wave resonator (4) are different. When a difference (D) (degrees) between the propagation direction of the surface acoustic waves in the first surface acoustic wave resonator and the propagation direction of the surface acoustic waves in the second surface acoustic wave resonator is 50° or less, and the electromechanical coupling coefficient of the first surface acoustic wave resonator is set as k2(1) and the electromechanical coupling coefficient of the second resonator is set as k2(2), k2(1) ≥ 0.0002 and k2(2) ≥ 0.0002.

Description

温度センサTemperature sensor
　本発明は、例えば、水蒸気ガス配管の温度、体温、及び風呂の温度などの－２０℃～１５０℃の温度範囲において温度を測定するための温度センサに関し、より詳細には、複数の弾性表面波共振子の共振特性の差により温度を測定する温度センサに関する。 The present invention relates to a temperature sensor for measuring a temperature in a temperature range of −20 ° C. to 150 ° C. such as a temperature of a steam gas pipe, a body temperature, and a bath temperature, and more specifically, a plurality of surface acoustic waves. The present invention relates to a temperature sensor that measures temperature based on a difference in resonance characteristics of a resonator.
　近年、弾性表面波共振子の周波数温度特性を利用して温度を測定する装置が種々提案されている。 In recent years, various apparatuses for measuring temperature using the frequency temperature characteristics of surface acoustic wave resonators have been proposed.
　例えば、下記の特許文献１には、図１６に示す温度検出装置が開示されている。温度検出装置１００１では、水晶基板１００２上に、第１及び第２の弾性表面波共振子１００３，１００４が構成されている。第１及び第２の弾性表面波共振子１００３及び１００４は、ＩＤＴ電極と、ＩＤＴ電極の弾性表面波伝搬方向両側に配置された反射器とを有する。第１の弾性表面波共振子１００３に第１のオペアンプ１００５が接続されている。同様に、第２の弾性表面波共振子１００４に第２のオペアンプ１００７が接続されている。第１，第２の弾性表面波共振子１００３，１００４の出力が、検出回路１０１０に与えられる。 For example, the following Patent Document 1 discloses a temperature detection device shown in FIG. In the temperature detection device 1001, first and second surface acoustic wave resonators 1003 and 1004 are configured on a quartz substrate 1002. The first and second surface acoustic wave resonators 1003 and 1004 include IDT electrodes and reflectors disposed on both sides of the IDT electrode in the surface acoustic wave propagation direction. A first operational amplifier 1005 is connected to the first surface acoustic wave resonator 1003. Similarly, a second operational amplifier 1007 is connected to the second surface acoustic wave resonator 1004. Outputs of the first and second surface acoustic wave resonators 1003 and 1004 are given to the detection circuit 1010.
　図１７は、第１の弾性表面波共振子１００３の周波数温度特性ｆ１と、第２の弾性表面波共振子１００４の周波数温度特性ｆ２とを示す。図１７から明らかなように、共振周波数の周波数温度特性ｆ１，ｆ２は、二次曲線のような形を有する。ある温度域、例えば図１７のＴ１からＴ２の間の温度域では、共振周波数差ｆ２－ｆ１は温度に対して直線的な関係を有する。そこで、特許文献１では、共振周波数差（ｆ２－ｆ１）の差が温度に対して直線的に変化する温度域において、共振周波数差により温度を測定することができるとされている。 FIG. 17 shows a frequency temperature characteristic f1 of the first surface acoustic wave resonator 1003 and a frequency temperature characteristic f2 of the second surface acoustic wave resonator 1004. As apparent from FIG. 17, the frequency temperature characteristics f1 and f2 of the resonance frequency have a shape like a quadratic curve. In a certain temperature range, for example, a temperature range between T1 and T2 in FIG. 17, the resonance frequency difference f2-f1 has a linear relationship with the temperature. Therefore, in Patent Document 1, it is supposed that the temperature can be measured by the resonance frequency difference in a temperature range where the difference of the resonance frequency difference (f2-f1) changes linearly with respect to the temperature.
　また、特許文献１では、第１の弾性表面波共振子１００３の表面波伝搬方向と、第２の弾性表面波共振子１００４の表面波伝搬方向とを９０°異ならせた構成も開示されている。 Patent Document 1 also discloses a configuration in which the surface acoustic wave propagation direction of the first surface acoustic wave resonator 1003 and the surface acoustic wave propagation direction of the second surface acoustic wave resonator 1004 are different by 90 °. .
　特許文献１では、２つの弾性表面波共振子１００３，１００４の共振周波数の差を利用して温度を決定している。従って、絶対的な温度と周波数との基準を用いずともよく、温度を高精度に測定することができると記載されている。 In Patent Document 1, the temperature is determined by utilizing the difference between the resonance frequencies of the two surface acoustic wave resonators 1003 and 1004. Therefore, it is described that the temperature can be measured with high accuracy without using an absolute temperature and frequency reference.
　別の例として、下記の非特許文献１には、１つの水晶基板上に２つの弾性表面波共振子が構成されている温度検出装置が開示されている。図１８は、非特許文献１に記載の温度検出装置における温度と２つの弾性表面波共振子の共振周波数差との関係を示し、図１９は該温度検出装置における反射特性Ｓ１１の周波数特性を示す。非特許文献１では、ここでは、水晶基板上に伝播方向を変えた２つのＩＤＴが形成されており、上記特許文献１の場合と同様に、２つの共振周波数の差によって温度を計測している。具体的にはＹカット水晶基板、オイラー角で表示すると（０°，９０°，ψ）の水晶基板を用いており、その伝播方向はψ＝３６度と４５度であり、それぞれのＴＣＦは１２ｐｐｍ／℃、－１２ｐｐｍ／℃となっている。 As another example, Non-Patent Document 1 below discloses a temperature detection device in which two surface acoustic wave resonators are formed on one quartz substrate. 18 shows the relationship between the temperature in the temperature detection device described in Non-Patent Document 1 and the resonance frequency difference between the two surface acoustic wave resonators, and FIG. 19 shows the frequency characteristic of the reflection characteristic S11 in the temperature detection device. . In Non-Patent Document 1, here, two IDTs having different propagation directions are formed on a quartz substrate, and the temperature is measured by the difference between the two resonance frequencies as in the case of Patent Document 1. . Specifically, a Y-cut quartz substrate and a quartz substrate of (0 °, 90 °, ψ) when expressed in Euler angles are used, the propagation directions are ψ = 36 ° and 45 °, and each TCF is 12 ppm. / ° C and -12 ppm / ° C.
　また、下記の非特許文献２では、水晶基板上に伝播方向を変えた２つのＩＤＴが形成されており、具体的には３５度回転Ｙカット水晶基板、オイラー角で表示すると（０°，１２５°，ψ）の水晶基板を用いている。弾性表面波の伝播方向はψ＝０度と３５度であり、それぞれのＴＣＦは１５ｐｐｍ／℃、３５ｐｐｍ／℃となっている。 Further, in the following Non-Patent Document 2, two IDTs having different propagation directions are formed on a quartz substrate. Specifically, when a 35-degree rotated Y-cut quartz substrate is displayed with Euler angles (0 °, 125 A quartz substrate of °, ψ) is used. The propagation directions of the surface acoustic waves are ψ = 0 degrees and 35 degrees, and the TCFs are 15 ppm / ° C. and 35 ppm / ° C., respectively.
ＷＯ０１／０４２７５２WO01 / 042752
　特許文献１では、１つの水晶基板１００２上に構成された２つの弾性表面波共振子１００３，１００４の弾性表面波伝搬方向を９０°異ならせることは開示されているものの、具体的な水晶基板の方位角についてはＳＴカットと記載されているだけである。すなわち、特許文献１には、様々な温度範囲で高精度に温度を測定し得る構成は具体的に示されていない。 Although Patent Document 1 discloses that the surface acoustic wave propagation directions of the two surface acoustic wave resonators 1003 and 1004 formed on one crystal substrate 1002 are different by 90 °, The azimuth is only described as ST cut. That is, Patent Document 1 does not specifically show a configuration capable of measuring temperature with high accuracy in various temperature ranges.
　上記のように、特許文献１では、第１の弾性表面波共振子と第２の弾性表面波共振子の弾性表面波伝搬方向を異ならせる構成として、両者の伝搬角を９０°異ならせた構成が示されている。しかしながら、伝搬角を９０°異ならせた場合、大きな水晶基板を用いなければならない。従って、小型化を進めることができない。 As described above, in Patent Document 1, as the configuration in which the surface acoustic wave propagation directions of the first surface acoustic wave resonator and the second surface acoustic wave resonator are made different, the propagation angles of the two are made 90 ° different from each other. It is shown. However, when the propagation angle is varied by 90 °, a large quartz substrate must be used. Therefore, downsizing cannot be promoted.
　非特許文献１および非特許文献２では、１つの水晶基板上に構成された２つの弾性表面波共振子の弾性表面波伝搬方向を異ならせ、温度を測定することは開示されている。しかし、用いられているオイラー角では弾性表面波共振子の電気機械結合係数が小さい範囲にある。従って、弾性表面波共振子の出力を十分な大きさにできず、高精度に温度を測定することができない。 Non-Patent Document 1 and Non-Patent Document 2 disclose that the surface acoustic wave propagation directions of two surface acoustic wave resonators formed on one quartz substrate are made different to measure the temperature. However, the electromechanical coupling coefficient of the surface acoustic wave resonator is in a small range at the Euler angle used. Therefore, the output of the surface acoustic wave resonator cannot be made sufficiently large, and the temperature cannot be measured with high accuracy.
　本発明の目的は、第１及び第２の弾性表面波共振子の特性差を利用して、－２０℃～１５０℃の温度範囲内の温度を高精度に測定することができ、かつ小型化を図ることができる温度センサを提供することにある。 An object of the present invention is to use the characteristic difference between the first and second surface acoustic wave resonators to measure a temperature within a temperature range of −20 ° C. to 150 ° C. with high accuracy and to reduce the size. An object of the present invention is to provide a temperature sensor capable of achieving
　本発明の温度センサは、－２０℃～１５０℃の範囲内の温度を測定するための温度センサであって、水晶基板と、前記水晶基板上に構成された第１の弾性表面波共振子と、前記水晶基板上に構成されている第２の弾性表面波共振子とを備える。本発明では、前記第１及び第２の弾性表面波共振子の－２０℃～１５０℃における周波数温度係数を下記の式で示されるＴＣＦとしたときに、第１及び第２の弾性表面波共振子のＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、かつ第１の弾性表面波共振子のＴＣＦと、第２の弾性表面波共振子のＴＣＦの極性が異なっており、かつ前記第１の弾性表面波共振子における弾性表面波の伝搬方向と、前記第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下であり、かつ前記第１の弾性表面波共振子の電気機械結合係数をｋ２（１）、前記第２の共振子の電気機械結合係数をｋ２（２）としたときに、ｋ２（１）≧０．０００２かつｋ２（２）≧０．０００２である。 A temperature sensor according to the present invention is a temperature sensor for measuring a temperature within a range of −20 ° C. to 150 ° C., and includes a quartz substrate and a first surface acoustic wave resonator formed on the quartz substrate. And a second surface acoustic wave resonator formed on the quartz substrate. In the present invention, when the frequency temperature coefficient at −20 ° C. to 150 ° C. of the first and second surface acoustic wave resonators is TCF expressed by the following equation, the first and second surface acoustic wave resonances are performed. The absolute value of the TCF of the child is 10 ppm / ° C. or more, the TCF of the first surface acoustic wave resonator and the TCF of the second surface acoustic wave resonator are different, and the first elasticity The difference D (degree) between the propagation direction of the surface acoustic wave in the surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less, and the first elastic surface When the electromechanical coupling coefficient of the wave resonator is k 2 (1) and the electromechanical coupling coefficient of the second resonator is k 2 (2), k 2 (1) ≧ 0.0002 and k 2 ( 2) ≧ 0.0002.
　ＴＣＦ＝Ｖ－１（３５℃）×［（Ｖ（１５０℃）－Ｖ（－２０℃））／１７０℃］－ＬＥＣ　…式（１） TCF = V −1 (35 ° C.) × [(V (150 ° C.) − V (−20 ° C.)) / 170 ° C.] − LEC Formula (1)
　なお、式（１）中、Ｖは音速（ｍ／秒）を示し、Ｖ－１（３５℃）は、３５℃における音速の逆数を意味し、Ｖ（１５０℃）及びＶ（－２０℃）は、それぞれ、１５０℃及び－２０℃における音速（ｍ／秒）を示し、ＬＥＣは水晶基板の線膨張係数（単位は１／℃）を示す。 In the formula (1), V represents the speed of sound (m / sec), V −1 (35 ° C.) means the reciprocal of the sound speed at 35 ° C., and V (150 ° C.) and V (−20 ° C.) Represents the sound velocity (m / sec) at 150 ° C. and −20 ° C., respectively, and LEC represents the linear expansion coefficient (unit: 1 / ° C.) of the quartz substrate.
　本発明に係る温度センサのある特定の局面では、第１及び第２の弾性表面波共振子において、弾性表面波としてレイリー波を利用しており、前記第１及び第２の弾性表面波共振子における水晶基板のオイラー角を、それぞれ、第１のオイラー角（φ，θ，ψ１）及び第２のオイラー角（φ，θ，ψ２）としたとき、第１のオイラー角と第２のオイラー角とが、下記の表１～３に示す何れかの組み合わせを満たしている。 In a specific aspect of the temperature sensor according to the present invention, in the first and second surface acoustic wave resonators, a Rayleigh wave is used as the surface acoustic wave, and the first and second surface acoustic wave resonators are used. The first Euler angle and the second Euler angle when the Euler angles of the quartz substrate in FIG. 1 are the first Euler angles (φ, θ, ψ1) and the second Euler angles (φ, θ, ψ2), respectively. Satisfy one of the combinations shown in Tables 1 to 3 below.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
　本発明に係る温度センサの他の特定の局面では、第１及び第２の弾性表面波共振子において、弾性表面波として漏洩弾性表面波を利用しており、前記第１及び第２の弾性表面波共振子における水晶基板のオイラー角を、それぞれ、第１のオイラー角（φ，θ，ψ１）及び第２のオイラー角（φ，θ，ψ２）としたとき、第１のオイラー角と第２のオイラー角とが、下記の表４に示す何れかの組み合わせを満たしている。 In another specific aspect of the temperature sensor according to the present invention, in the first and second surface acoustic wave resonators, a leaky surface acoustic wave is used as the surface acoustic wave, and the first and second surface acoustic waves are used. When the Euler angles of the quartz substrate in the wave resonator are the first Euler angles (φ, θ, ψ1) and the second Euler angles (φ, θ, ψ2), respectively, the first Euler angles and the second Euler angles The Euler angles satisfy any combination shown in Table 4 below.
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
　本発明に係る温度センサのさらに他の特定の局面では、前記第１の表面波共振子において、弾性表面波としてレイリー波を利用しており、前記第２の弾性表面波共振子において弾性表面波として漏洩弾性表面波を利用しており、前記第１及び第２の弾性表面波共振子における前記水晶基板のオイラー角が、下記の表５に示す何れかの範囲である。 In still another specific aspect of the temperature sensor according to the present invention, a Rayleigh wave is used as a surface acoustic wave in the first surface acoustic wave resonator, and a surface acoustic wave is used in the second surface acoustic wave resonator. In the first and second surface acoustic wave resonators, the Euler angle of the quartz crystal substrate is in one of the ranges shown in Table 5 below.
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　本発明に係る温度センサの他の局面では、前記第１の弾性表面波共振子が第１のＩＤＴ電極と、第１のＩＤＴ電極の弾性表面波伝搬方向両側に配置された反射器とを有し、前記第２の弾性表面波共振子が、ＩＤＴ電極と、ＩＤＴ電極の弾性表面波伝搬方向両側に配置された反射器とを有する。 In another aspect of the temperature sensor according to the present invention, the first surface acoustic wave resonator includes a first IDT electrode and reflectors arranged on both sides of the first IDT electrode in the surface acoustic wave propagation direction. The second surface acoustic wave resonator includes an IDT electrode and reflectors disposed on both sides of the surface acoustic wave propagation direction of the IDT electrode.
　上記レイリー波と漏洩弾性表面波を利用した本発明の温度センサの他の特定の局面では、前記水晶基板上に１つのＩＤＴ電極と、該ＩＤＴ電極の両側に配置されており、かつそれぞれが複数本の電極指を有する第１及び第２の反射器とが設けられており、前記ＩＤＴ電極及び第１及び第２の反射器により、レイリー波を利用した前記第１の弾性表面波共振子と、漏洩弾性表面波を用いた第２の弾性表面波共振子とが構成されている。前記ＩＤＴ電極が互いの電極指が間挿されるように配置された第１，第２のくし歯電極を有している。温度センサは前記第１，第２のくし歯電極において電極指の先端を結ぶ線を第１、第２仮想直線とし、前記第１、第２仮想直線がレイリー波伝搬方向と平行である。温度センサは、第１仮想直線と前記ＩＤＴ電極の第２反射器側最外電極指との交点を通り、かつＬＳＡＷ伝搬方向に平行に延びる直線を第３仮想直線とし、第２仮想直線と、前記ＩＤＴ電極の第１反射器側最外電極指との交点を通りかつＬＳＡＷ伝搬方向に平行に延びる直線を第４仮想直線としたときに、第１反射器の電極指の一端が第１仮想直線上に、他端が第４仮想直線上に位置しており、第２反射器の電極指の一端が第３仮想直線上に、他端が第２仮想直線上に位置している。第１及び第２の反射器の複数本の前記電極指が、それぞれ、レイリー波及び漏洩弾性表面波を反射し得る。 In another specific aspect of the temperature sensor of the present invention using the Rayleigh wave and the leaky surface acoustic wave, one IDT electrode is disposed on the quartz substrate and both sides of the IDT electrode, and a plurality of each is provided. First and second reflectors having electrode fingers, and the first surface acoustic wave resonator using Rayleigh waves by the IDT electrode and the first and second reflectors; The second surface acoustic wave resonator using the leaky surface acoustic wave is configured. The IDT electrode has first and second comb electrodes arranged so that mutual electrode fingers are inserted. In the temperature sensor, the lines connecting the tips of the electrode fingers in the first and second comb electrodes are defined as first and second virtual straight lines, and the first and second virtual straight lines are parallel to the Rayleigh wave propagation direction. The temperature sensor has a third imaginary straight line passing through the intersection of the first imaginary straight line and the outermost electrode finger of the IDT electrode on the second reflector side and extending parallel to the LSAW propagation direction. When a straight line extending through the intersection of the IDT electrode with the outermost electrode finger on the first reflector side and extending parallel to the LSAW propagation direction is a fourth virtual straight line, one end of the electrode finger of the first reflector is the first virtual line. On the straight line, the other end is located on the fourth virtual straight line, one end of the electrode finger of the second reflector is located on the third virtual straight line, and the other end is located on the second virtual straight line. The plurality of electrode fingers of the first and second reflectors can reflect the Rayleigh wave and the leaky surface acoustic wave, respectively.
　従って、１つのＩＤＴ電極及び上記第１及び第２の反射器により、第１及び第２の弾性表面波共振子を構成することができる。よって、温度センサのさらなる小型化を図ることができる。 Therefore, the first and second surface acoustic wave resonators can be constituted by one IDT electrode and the first and second reflectors. Therefore, the temperature sensor can be further reduced in size.
　この場合、より具体的には、前記第１，第２の反射器の電極指の延びる方向が、前記ＩＤＴ電極の前記電極指の延びる方向と平行であり、前記ＩＤＴ電極の前記電極指の交叉幅をＷ（単位はｍ）、前記第１及び第２の反射器と、前記ＩＤＴ電極の最外側電極指同士間の間隔をＬ（単位はｍ）、前記第１及び第２の反射器の前記電極指の長さをＨ（単位はｍ）、前記レイリー波と前記漏洩弾性表面波の伝搬方向の差をＤ（度）としたときに、Ｈ＞Ｗ＋Ｌ×ｔａｎＤとされていることが好ましい。 In this case, more specifically, the extending direction of the electrode fingers of the first and second reflectors is parallel to the extending direction of the electrode fingers of the IDT electrode, and the crossing of the electrode fingers of the IDT electrode is performed. The width is W (unit is m), the distance between the first and second reflectors and the outermost electrode fingers of the IDT electrode is L (unit is m), and the first and second reflectors are When the length of the electrode finger is H (unit is m) and the difference in propagation direction between the Rayleigh wave and the leaky surface acoustic wave is D (degrees), it is preferable that H> W + L × tanD. .
　本発明に係る温度センサのさらに他の特定の局面では、前記温度センサが使用される温度範囲において、前記第１の弾性表面波共振子の共振周波数Ｆ１と、前記第２の弾性表面波共振子の共振周波数Ｆ２とが、式（２）で示すΔＦ以上離れているように構成されていることが好ましい。 In still another specific aspect of the temperature sensor according to the present invention, a resonance frequency F1 of the first surface acoustic wave resonator and the second surface acoustic wave resonator in a temperature range in which the temperature sensor is used. It is preferable that the resonance frequency F2 is configured so as to be more than ΔF shown in the equation (2).
　ΔＦ=１／５×Ｆ１／（Ｆ１ｈ－Ｆ１ｌ）＋１／５×Ｆ２／（Ｆ２ｈ－Ｆ２ｌ） ・・・式（２） ΔF = 1/5 × F1 / (F1h−F1l) + 1/5 × F2 / (F2h−F2l) Equation (2)
　なお、式（２）中Ｆ１ｈはＦ１における振幅強度の１／√２の強度となる周波数の内、高い方の周波数であり、Ｆ１ｌはＦ１における振幅強度の１／√２の強度となる周波数の内、低い方の周波数を示す。また、Ｆ２ｈはＦ２における振幅強度の１／√２の強度となる周波数の内、高い方の周波数であり、Ｆ２ｌはＦ２における振幅強度の１／√２の強度となる周波数の内、低い方の周波数を示す。 In Formula (2), F1h is a higher frequency among the frequencies that are 1 / √2 of the amplitude intensity in F1, and F1l is a frequency that is 1 / √2 of the amplitude intensity in F1. Of these, the lower frequency is shown. F2h is a higher frequency among the frequencies that are 1 / √2 of the amplitude intensity in F2, and F2l is a lower frequency among the frequencies that are 1 / √2 of the amplitude intensity in F2. Indicates the frequency.
　本発明に係る温度センサでは、第１及び第２の弾性表面波共振子のＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、第１の弾性表面波共振子のＴＣＦの極性と、第２の弾性表面波共振子のＴＣＦの極性とが異なっているので、第１の弾性表面波共振子のＴＣＦと、第２の弾性表面波共振子のＴＣＦとの差ΔＴＣＦが２０ｐｐｍ／℃以上と大きい。すなわち、共振周波数差の温度による変化が大きいため、－２０℃～１５０℃の温度範囲で温度を高精度に測定することができる。 In the temperature sensor according to the present invention, the absolute value of the TCF of the first and second surface acoustic wave resonators is 10 ppm / ° C. or more, the polarity of the TCF of the first surface acoustic wave resonator, and the second elastic wave Since the polarity of the TCF of the surface acoustic wave resonator is different, the difference ΔTCF between the TCF of the first surface acoustic wave resonator and the TCF of the second surface acoustic wave resonator is as large as 20 ppm / ° C. or more. That is, since the change of the resonance frequency difference with temperature is large, the temperature can be measured with high accuracy in the temperature range of −20 ° C. to 150 ° C.
　なお、第１の弾性表面波共振子のＴＣＦと、第２の弾性表面波共振子のＴＣＦの差ΔＴＣＦが大きい場合、温度を高精度に測定することができる。しかしながら、一方のＴＣＦの絶対値が１０ｐｐｍ／℃未満、例えば０ｐｐｍ／℃に近い場合には、温度による周波数変化量が周波数読取精度以下に小さくなる。従って、温度測定ができない。 In addition, when the difference ΔTCF between the TCF of the first surface acoustic wave resonator and the TCF of the second surface acoustic wave resonator is large, the temperature can be measured with high accuracy. However, when the absolute value of one TCF is less than 10 ppm / ° C., for example, close to 0 ppm / ° C., the amount of frequency change due to temperature becomes less than the frequency reading accuracy. Therefore, the temperature cannot be measured.
　本発明によれば、上記ΔＴＣＦが２０ｐｐｍ／℃以上と大きいだけでなく、第１，第２の弾性表面波共振子のＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、かつ両者の極性が異なっている。従って、上記のように－２０℃～１５０℃の温度で温度を高精度に測定することが可能となる。 According to the present invention, not only the above ΔTCF is as large as 20 ppm / ° C. or more, but also the absolute value of TCF of the first and second surface acoustic wave resonators is 10 ppm / ° C. or more, and both polarities are different. Yes. Therefore, the temperature can be measured with high accuracy at a temperature of −20 ° C. to 150 ° C. as described above.
　さらに、第１，第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下であるので、温度センサを小型化することができる。 Furthermore, since the difference D (degree) from the propagation direction of the surface acoustic wave in the first and second surface acoustic wave resonators is 50 ° or less, the temperature sensor can be miniaturized.
　しかも、表１～３、表４、表５に示すオイラー角の水晶基板を用いた弾性表面波共振子の周波数温度係数ＴＣＦは、－２０℃～１５０℃の温度範囲で、温度に対して直線的な関係を有する。従って、それによっても、－２０℃～１５０℃の温度範囲で温度を高精度に測定することができる。 In addition, the frequency temperature coefficient TCF of the surface acoustic wave resonator using the Euler angle quartz crystal substrates shown in Tables 1 to 3, 4 and 5 is linear with respect to the temperature in the temperature range of −20 ° C. to 150 ° C. Have the same relationship. Accordingly, it is possible to measure the temperature with high accuracy in the temperature range of -20 ° C to 150 ° C.
　よって、本発明の温度センサは、水蒸気ガス配管の温度、体温、及び風呂の温度などの－２０℃～１５０℃の温度範囲に属する温度を測定するのに好適に用いられる。 Therefore, the temperature sensor of the present invention is preferably used for measuring temperatures belonging to a temperature range of −20 ° C. to 150 ° C. such as the temperature of the steam gas pipe, the body temperature, and the temperature of the bath.
　また、本発明に係る温度センサでは、第１の弾性表面波共振子の共振周波数の温度特性及び第２の弾性表面波共振子の共振周波数の差を利用して温度を測定するものであるため、製造ばらつきによる誤差が生じ難い。また、被測定物の絶対温度を確実に測定することができる。 In the temperature sensor according to the present invention, the temperature is measured using the difference between the temperature characteristics of the resonance frequency of the first surface acoustic wave resonator and the resonance frequency of the second surface acoustic wave resonator. Errors due to manufacturing variations are less likely to occur. Further, the absolute temperature of the object to be measured can be reliably measured.
図１は、本発明の第１の実施形態に係る温度センサを説明するための模式的平面図である。FIG. 1 is a schematic plan view for explaining a temperature sensor according to a first embodiment of the present invention. 図２は、第１の実施形態の温度センサにおける第１の弾性表面波共振子の共振周波数温度特性と、第２の弾性表面波共振子の共振周波数温度特性とを示す図である。FIG. 2 is a diagram illustrating a resonance frequency temperature characteristic of the first surface acoustic wave resonator and a resonance frequency temperature characteristic of the second surface acoustic wave resonator in the temperature sensor of the first embodiment. 図３は、第１の実施形態の温度センサにおける、第１，第２の弾性表面波共振子の共振周波数差Δｆと、温度との関係を示す図である。FIG. 3 is a diagram showing the relationship between the temperature and the resonance frequency difference Δf of the first and second surface acoustic wave resonators in the temperature sensor of the first embodiment. 図４は、オイラー角（０°，４５°，ψ）の水晶基板を用いた場合のレイリー波を利用した弾性表面波共振子におけるＴＣＦ及び電気機械結合係数ｋ２と、オイラー角のψとの関係を示す図である。FIG. 4 shows the relationship between the TCF and the electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the Rayleigh wave and the Euler angle ψ when a quartz substrate with Euler angles (0 °, 45 °, ψ) is used. It is a figure which shows a relationship. 図５は、オイラー角（０°，４５°，ψ）の水晶基板を用いた場合のレイリー波を利用した弾性表面波共振子における伝搬方向［ψ＋ＰＦＡ］と、ψとの関係を示す図である。FIG. 5 is a diagram showing the relationship between ψ and the propagation direction [ψ + PFA] in a surface acoustic wave resonator using a Rayleigh wave when using a quartz substrate with Euler angles (0 °, 45 °, ψ). . 図６は、オイラー角（０°，１０°，ψ）の水晶基板を用いた場合の漏洩弾性表面波を利用した弾性表面波共振子におけるＴＣＦ及び電気機械結合係数ｋ２と、オイラー角のψとの関係を示す図である。FIG. 6 shows the TCF and electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the leaky surface acoustic wave when using the Euler angle (0 °, 10 °, ψ) quartz substrate, and the Euler angle ψ. It is a figure which shows the relationship. 図７は、オイラー角（０°，１０°，ψ）の水晶基板を用いた場合の漏洩弾性表面波を利用した弾性表面波共振子における伝搬方向［ψ＋ＰＦＡ］と、ψとの関係を示す図である。FIG. 7 is a diagram showing the relationship between ψ and the propagation direction [ψ + PFA] in a surface acoustic wave resonator using a leaky surface acoustic wave when a Euler angle (0 °, 10 °, ψ) quartz substrate is used. It is. 図８は、本発明の第１の実施形態の他の変形例に係る温度センサの模式的平面図である。FIG. 8 is a schematic plan view of a temperature sensor according to another modification of the first embodiment of the present invention. 図９（ａ）は、本発明の第２の実施形態に係る温度センサの模式的平面図であり、（ｂ）は、その好ましい構造を説明するための模式的平面図である。FIG. 9A is a schematic plan view of a temperature sensor according to the second embodiment of the present invention, and FIG. 9B is a schematic plan view for explaining a preferred structure thereof. 図１０は、オイラー角（０°，３５°，ψ）の水晶基板を用いた場合のレイリー波を利用した弾性表面波共振子におけるＴＣＦ及び電気機械結合係数ｋ２と、オイラー角のψとの関係を示す図である。FIG. 10 shows the relationship between the TCF and the electromechanical coupling coefficient k 2 in the surface acoustic wave resonator using the Rayleigh wave and the Euler angle ψ when a quartz substrate with Euler angles (0 °, 35 °, ψ) is used. It is a figure which shows a relationship. 図１１は、オイラー角（０°，３５°，ψ）の水晶基板を用いた場合の漏洩弾性表面波を利用した弾性表面波共振子における伝搬方向［ψ＋ＰＦＡ］と、ψとの関係を示す図である。FIG. 11 is a diagram showing the relationship between ψ and the propagation direction [ψ + PFA] in a surface acoustic wave resonator using a leaky surface acoustic wave when a quartz substrate with Euler angles (0 °, 35 °, ψ) is used. It is. 図１２は、オイラー角（０°，３５°，ψ）の水晶基板を用いた場合の弾性表面波共振子におけるレイリー波及び漏洩弾性表面波の伝搬方向［ψ＋ＰＦＡ］とψとの関係を示す図である。FIG. 12 is a diagram showing a relationship between ψ and propagation directions [ψ + PFA] of Rayleigh waves and leaky surface acoustic waves in a surface acoustic wave resonator when a quartz substrate with Euler angles (0 °, 35 °, ψ) is used. It is. 図１３は、本発明の実施形態の温度センサにおける第１の弾性表面波共振子の反射特性Ｓ１１と周波数との関係を示し、第１の弾性表面波共振子の周波数Ｆ１と、第２の弾性表面波共振子の周波数Ｆ２とが極小値として表れている例を示す図である。FIG. 13 shows the relationship between the reflection characteristic S11 of the first surface acoustic wave resonator and the frequency in the temperature sensor of the embodiment of the present invention, the frequency F1 of the first surface acoustic wave resonator, and the second elasticity. It is a figure which shows the example in which the frequency F2 of a surface wave resonator appears as a minimum value. 図１４は、本発明の実施形態の温度センサにおける第１，第２の弾性表面波共振子の反射特性Ｓ１１と周波数との関係を示す図であり、第１，第２の周波数Ｆ１，Ｆ２が近接しており、第２の周波数Ｆ２を極小値として検出することができない例を示す図である。FIG. 14 is a diagram showing the relationship between the reflection characteristic S11 of the first and second surface acoustic wave resonators and the frequency in the temperature sensor according to the embodiment of the present invention, and the first and second frequencies F1 and F2 are shown. FIG. 6 is a diagram illustrating an example in which the second frequency F2 is close and cannot be detected as a minimum value. 図１５は、第１の弾性表面波共振子及び第２の弾性表面波共振子Ｓ１１の周波数特性において、第１の周波数Ｆ１及び第２の周波数Ｆ２を極小値として検出する方法を説明するための図である。FIG. 15 is a diagram for explaining a method of detecting the first frequency F1 and the second frequency F2 as minimum values in the frequency characteristics of the first surface acoustic wave resonator and the second surface acoustic wave resonator S11. FIG. 図１６は、従来の温度検出装置の一例を示す概略構成図である。FIG. 16 is a schematic configuration diagram illustrating an example of a conventional temperature detection device. 図１７は、従来の温度検出装置における温度測定原理を説明するための図である。FIG. 17 is a diagram for explaining a temperature measurement principle in a conventional temperature detection apparatus. 図１８は、従来の温度検出装置における温度と、２つの弾性表面波共振子の共振周波数差の関係を示す図である。FIG. 18 is a diagram illustrating a relationship between a temperature in a conventional temperature detection device and a resonance frequency difference between two surface acoustic wave resonators. 図１９は、従来の温度検出装置における、反射特性Ｓ１１の周波数特性を示す図である。FIG. 19 is a diagram showing the frequency characteristic of the reflection characteristic S11 in the conventional temperature detection device.
　以下、本発明の具体的な実施形態を説明することにより、本発明を明らかにする。 Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention.
　（第１の実施形態）
　図１は、本発明の第１の実施形態に係る温度センサの模式的平面図である。 (First embodiment)
FIG. 1 is a schematic plan view of a temperature sensor according to the first embodiment of the present invention.
　温度センサ１は、水晶基板２を有する。水晶基板２上に、第１の弾性表面波共振子３及び第２の弾性表面波共振子４が構成されている。本実施形態では、第１の弾性表面波共振子３及び第２の弾性表面波共振子４においてレイリー波が励振され、該レイリー波による共振特性が利用される。 The temperature sensor 1 has a quartz substrate 2. On the quartz substrate 2, a first surface acoustic wave resonator 3 and a second surface acoustic wave resonator 4 are formed. In the present embodiment, Rayleigh waves are excited in the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4, and the resonance characteristics of the Rayleigh waves are used.
　第１の弾性表面波共振子３は、第１のＩＤＴ電極５と、第１のＩＤＴ電極５の弾性表面波伝搬方向両側に配置された反射器６，７とを有する。同様に、第２の弾性表面波共振子４は、ＩＤＴ電極８と、ＩＤＴ電極８の弾性表面波伝搬方向両側に配置された反射器９，１０とを有する。ＩＤＴ電極５，８は、それぞれ、一対のバスバー５ｂ，５ｃ，８ｂ，８ｃを有する。同様に、反射器６，７，９，１０もまた、一対のバスバー６ｂ，６ｃ，７ｂ，７ｃ，９ｂ，９ｃ，１０ｂ，１０ｃを有する。第１，第２の弾性表面波共振子３，４は、上記のように、１ポート型弾性表面波共振子である。 The first surface acoustic wave resonator 3 includes a first IDT electrode 5 and reflectors 6 and 7 disposed on both sides of the first IDT electrode 5 in the surface acoustic wave propagation direction. Similarly, the second surface acoustic wave resonator 4 includes an IDT electrode 8 and reflectors 9 and 10 disposed on both sides of the IDT electrode 8 in the surface acoustic wave propagation direction. The IDT electrodes 5 and 8 each have a pair of bus bars 5b, 5c, 8b and 8c. Similarly, the reflectors 6, 7, 9, and 10 also have a pair of bus bars 6b, 6c, 7b, 7c, 9b, 9c, 10b, and 10c. As described above, the first and second surface acoustic wave resonators 3 and 4 are one-port surface acoustic wave resonators.
　第１のＩＤＴ電極５、反射器６，７、第２のＩＤＴ電極８及び反射器９，１０は、適宜の金属もしくは合金からなる。本実施形態では、上記金属もしくは合金として、Ａｌが用いられている。 The first IDT electrode 5, the reflectors 6 and 7, the second IDT electrode 8 and the reflectors 9 and 10 are made of an appropriate metal or alloy. In this embodiment, Al is used as the metal or alloy.
　第１の弾性表面波共振子３の弾性表面波伝搬方向Ａ１と、第２の弾性表面波共振子４の弾性表面波伝搬方向Ａ２とは図示のように異なっている。本実施形態では、第１の弾性表面波共振子３の第１のオイラー角（φ，θ，ψ１）は（０°，４５°，５°）である。なお、上記オイラー角のψは、水晶基板のＸ軸（図１参照）に対する伝搬方位を示す。 The surface acoustic wave propagation direction A1 of the first surface acoustic wave resonator 3 and the surface acoustic wave propagation direction A2 of the second surface acoustic wave resonator 4 are different as shown in the figure. In the present embodiment, the first Euler angles (φ, θ, ψ1) of the first surface acoustic wave resonator 3 are (0 °, 45 °, 5 °). The Euler angle ψ indicates the propagation direction with respect to the X axis (see FIG. 1) of the quartz substrate.
　第１の弾性表面波共振子３では、弾性表面波伝搬方向Ａ１が、オイラー角のψ１＋ＰＦＡの方向となる。従って、第１の弾性表面波共振子３の弾性表面波伝搬方向は、第１のオイラー角が（０°，４５°，５°）であるため、５°＋１３．０°＝１８．０°の方向とされている。 In the first surface acoustic wave resonator 3, the surface acoustic wave propagation direction A1 is the direction of Euler angle ψ1 + PFA. Accordingly, the surface acoustic wave propagation direction of the first surface acoustic wave resonator 3 is 5 ° + 13.0 ° = 18.0 ° because the first Euler angles are (0 °, 45 °, 5 °). It is said that the direction.
　すなわち、第１の弾性表面波共振子３では、弾性表面波伝搬方向Ａ１が、第１のオイラー角のψ１に対して１３．０°の角度を成すように、ＩＤＴ電極５及び反射器６，７が配置されている。図示のように、このような弾性表面波伝搬方向Ａ１を実現するために、第１のＩＤＴ電極５においては、複数本の電極指が間挿し合っている部分が平行四辺形の形状とされており、反射器６，７も略平行四辺形の形状とされている。そして、上記弾性表面波伝搬方向Ａ１に沿って伝搬する弾性表面波を反射させるように反射器６，７が配置されている。 That is, in the first surface acoustic wave resonator 3, the surface acoustic wave propagation direction A1 forms an angle of 13.0 ° with respect to the first Euler angle ψ1, and the IDT electrode 5 and the reflectors 6, 7 is arranged. As shown in the drawing, in order to realize such a surface acoustic wave propagation direction A1, in the first IDT electrode 5, a portion where a plurality of electrode fingers are interleaved is formed in a parallelogram shape. The reflectors 6 and 7 are also substantially parallelogram shaped. And the reflectors 6 and 7 are arrange | positioned so that the surface acoustic wave which propagates along the said surface acoustic wave propagation | transmission direction A1 may be reflected.
　他方、第２の弾性表面波共振子４の第２のオイラー角（φ，θ，ψ２）は（０°，４５°，３５°）である。これに対して、弾性表面波伝搬方向Ａ２は、３５°＋（－３．５°）＝３１．５°とされている。すなわち、第２の弾性表面波共振子４では、弾性表面波伝搬方向Ａ２が、第２のオイラー角のψ２に対して－３．５°の角度を成すように、ＩＤＴ電極８及び反射器９，１０が配置されている。図示のように、このような弾性表面波伝搬方向Ａ２を実現するために、第２のＩＤＴ電極８においては、複数本の電極指が間挿し合っている部分が平行四辺形の形状とされており、反射器９，１０も略平行四辺形の形状とされている。そして、上記弾性表面波伝搬方向Ａ２に沿って伝搬する弾性表面波を反射させるように反射器９，１０が配置されている。 On the other hand, the second Euler angles (φ, θ, ψ2) of the second surface acoustic wave resonator 4 are (0 °, 45 °, 35 °). On the other hand, the surface acoustic wave propagation direction A2 is set to 35 ° + (− 3.5 °) = 31.5 °. That is, in the second surface acoustic wave resonator 4, the IDT electrode 8 and the reflector 9 are arranged such that the surface acoustic wave propagation direction A 2 forms an angle of −3.5 ° with respect to the second Euler angle ψ 2. , 10 are arranged. As shown in the drawing, in order to realize such a surface acoustic wave propagation direction A2, in the second IDT electrode 8, a portion where a plurality of electrode fingers are interleaved is formed in a parallelogram shape. The reflectors 9 and 10 are also substantially parallelogram shaped. And the reflectors 9 and 10 are arrange | positioned so that the surface acoustic wave which propagates along the said surface acoustic wave propagation | transmission direction A2 may be reflected.
　本実施形態の温度センサ１では、第１の弾性表面波共振子３の－２０℃～１５０℃における周波数温度係数ＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、かつ第１の弾性表面波共振子のＴＣＦと、第２の弾性表面波共振子４のＴＣＦの極性が異なっている。従って、後述する実験例から明らかなように、－２０℃～１５０℃の範囲の温度を高精度に測定することができる。また、弾性表面波共振子３，４の共振周波数差を利用しているため、製造ばらつきによる影響を受け難い。加えて、弾性表面波共振子３，４が上記のように配置されているため、小型化を図ることができる。これを、以下においてより具体的に説明する。 In the temperature sensor 1 of the present embodiment, the absolute value of the frequency temperature coefficient TCF at −20 ° C. to 150 ° C. of the first surface acoustic wave resonator 3 is 10 ppm / ° C. or more, and the first surface acoustic wave resonator. And the TCF of the second surface acoustic wave resonator 4 are different in polarity. Therefore, as is clear from the experimental examples described later, it is possible to measure a temperature in the range of −20 ° C. to 150 ° C. with high accuracy. Further, since the resonance frequency difference between the surface acoustic wave resonators 3 and 4 is used, it is difficult to be affected by manufacturing variations. In addition, since the surface acoustic wave resonators 3 and 4 are arranged as described above, the size can be reduced. This will be described more specifically below.
　なお、上記ＴＣＦは、下記の式（１）で表される。 The TCF is expressed by the following formula (1).
　ＴＣＦ＝Ｖ－１（３５℃）×［（Ｖ（１５０℃）－Ｖ（－２０℃））／１７０℃］－ＬＥＣ　…式（１） TCF = V −1 (35 ° C.) × [(V (150 ° C.) − V (−20 ° C.)) / 170 ° C.] − LEC Formula (1)
　なお、式（１）中、Ｖは音速（ｍ／秒）を示し、Ｖ－１（３５℃）は、３５℃における音速の逆数を意味し、Ｖ（１５０℃）及びＶ（－２０℃）は、それぞれ、１５０℃及び－２０℃における音速（ｍ／秒）を示し、ＬＥＣは水晶基板の線膨張係数（単位は１／℃）を示す。 In the formula (1), V represents the speed of sound (m / sec), V −1 (35 ° C.) means the reciprocal of the sound speed at 35 ° C., and V (150 ° C.) and V (−20 ° C.) Represents the sound velocity (m / sec) at 150 ° C. and −20 ° C., respectively, and LEC represents the linear expansion coefficient (unit: 1 / ° C.) of the quartz substrate.
　まず、図２及び図３を参照して、温度センサ１における温度測定原理を説明する。 First, the temperature measurement principle of the temperature sensor 1 will be described with reference to FIGS.
　図２は、第１及び第２の弾性表面波共振子３，４の共振周波数の温度特性を示す図である。図２から明らかなように、第１の弾性表面波共振子３及び第２の弾性表面波共振子４の共振周波数は、－２０℃～１５０℃の温度範囲で、直線性を有する。そして、第１の弾性表面波共振子３では、共振周波数は温度が上がるにつれて高くなっている。すなわち、上記温度範囲でＴＣＦが正の値である。これに対して、第２の弾性表面波共振子４では、図２に示す温度範囲において、ＴＣＦが負の値となっている。従って、上述した－２０℃～１５０℃の温度範囲において、第１，第２の弾性表面波共振子３，４のＴＣＦの極性が異なっている。 FIG. 2 is a diagram showing temperature characteristics of the resonance frequencies of the first and second surface acoustic wave resonators 3 and 4. As is apparent from FIG. 2, the resonance frequencies of the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 have linearity in the temperature range of −20 ° C. to 150 ° C. In the first surface acoustic wave resonator 3, the resonance frequency increases as the temperature increases. That is, TCF is a positive value in the above temperature range. On the other hand, in the second surface acoustic wave resonator 4, the TCF has a negative value in the temperature range shown in FIG. Accordingly, the TCF polarities of the first and second surface acoustic wave resonators 3 and 4 are different in the temperature range of −20 ° C. to 150 ° C. described above.
　図３は、（第１の弾性表面波共振子３の共振周波数－第２の弾性表面波共振子４の共振周波数）＝Δｆと、温度との関係を示す図である。 FIG. 3 is a diagram showing the relationship between (resonance frequency of first surface acoustic wave resonator 3−resonance frequency of second surface acoustic wave resonator 4) = Δf and temperature.
　図２に示したように、第１の弾性表面波共振子３及び第２の弾性表面波共振子４の共振周波数の温度特性が上記温度範囲において直線的に変化するため、図３に示すように、Δｆもまた、温度が変化した場合、直線的に変化する。よって、図３から明らかなように、第１の弾性表面波共振子３と第２の弾性表面波共振子４との共振周波数差Δｆを求めれば、温度を検出することがきできる。 As shown in FIG. 2, since the temperature characteristics of the resonance frequency of the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 change linearly in the above temperature range, as shown in FIG. In addition, Δf also changes linearly when the temperature changes. Therefore, as apparent from FIG. 3, the temperature can be detected by obtaining the resonance frequency difference Δf between the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4.
　本実施形態の温度センサ１では、上記のように、１つの同じ水晶基板２上に構成された第１の弾性表面波共振子３と、第２の弾性表面波共振子４の共振周波数差を利用して、温度を検出する。１つの弾性表面波共振子の共振周波数の温度特性を利用した場合には、製造ばらつきにより基準となる温度が変動するため、正確に温度を検出することができない。これに対して、本実施形態の温度センサ１では、第１及び第２の弾性表面波共振子３，４の共振周波数差に基づいて温度を検出するため、製造ばらつきによる誤差が生じ難い。従って、温度を正確に検出することができる。 In the temperature sensor 1 of the present embodiment, as described above, the resonance frequency difference between the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 formed on the same quartz crystal substrate 2 is calculated. Use to detect temperature. When the temperature characteristic of the resonance frequency of one surface acoustic wave resonator is used, the temperature as a reference fluctuates due to manufacturing variations, and thus the temperature cannot be detected accurately. On the other hand, in the temperature sensor 1 of the present embodiment, the temperature is detected based on the resonance frequency difference between the first and second surface acoustic wave resonators 3 and 4, so that an error due to manufacturing variations hardly occurs. Therefore, the temperature can be detected accurately.
　また、第１の弾性表面波共振子３の弾性表面波伝搬方向Ａ１と、第２の弾性表面波伝搬方向Ａ２とは、３５．０°－３．５°－（５．０°＋１３．０°）＝１３．５°の角度を成している。従って、第１の弾性表面波共振子３と第２の弾性表面波共振子４とを近接配置することができる。 The surface acoustic wave propagation direction A1 of the first surface acoustic wave resonator 3 and the second surface acoustic wave propagation direction A2 are 35.0 ° −3.5 ° − (5.0 ° + 13.0). °) = 13.5 °. Therefore, the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 can be disposed close to each other.
　特許文献１に記載の弾性表面波伝搬方向を９０°異ならせた２つの弾性表面波共振子を構成した場合には、２つの弾性表面波共振子の配置スペースが大きくなるという問題があった。 When two surface acoustic wave resonators having different surface acoustic wave propagation directions described in Patent Document 1 by 90 ° are configured, there is a problem that an arrangement space for the two surface acoustic wave resonators becomes large.
　これに対して、本実施形態では、第１の弾性表面波共振子３及び第２の弾性表面波共振子４の設置スペースを小さくすることができる。従って、温度センサ１では、小型化を進めることができる。 On the other hand, in the present embodiment, the installation space for the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 can be reduced. Therefore, the temperature sensor 1 can be downsized.
　さらに、上記第１の弾性表面波共振子３の第１のオイラー角が（０°，４５°，５°）であり、第２の弾性表面波共振子４における第２のオイラー角が（０°，４５°，３５°）であるため、以下に示すように、第１の弾性表面波共振子３のＴＣＦと、第２の弾性表面波共振子４のＴＣＦの絶対値を１０ｐｐｍ／℃以上とし、すなわち、両者のＴＣＦの差を２０ｐｐｍ／℃以上とすることができる。また第１の弾性表面波共振子３の電気機械結合係数をｋ２（１）と、第２の弾性表面波共振子４の電気機械結合係数をｋ２（２）の絶対値はそれぞれｋ２（１）＝０．００１０、ｋ２（２）＝０．００１２５とｋ２（１）≧０．０００２かつｋ２（２）≧０．０００２であり、弾性表面波共振子の出力を十分な大きさにできる。よって、感度を高めることができ、温度を高精度に測定することができる。これを、様々なオイラー角の弾性表面波共振子についてのＴＣＦ（ｐｐｍ／℃）、電気機械結合係数ｋ２及びパワーフロー角ＰＦＡ（度）を示して説明する。 Further, the first Euler angle of the first surface acoustic wave resonator 3 is (0 °, 45 °, 5 °), and the second Euler angle in the second surface acoustic wave resonator 4 is (0 As shown below, the absolute values of the TCF of the first surface acoustic wave resonator 3 and the TCF of the second surface acoustic wave resonator 4 are 10 ppm / ° C. or more. That is, the difference between the two TCFs can be 20 ppm / ° C. or more. The electromechanical coupling coefficient of the first surface acoustic wave resonator 3 k 2 (1) and the absolute value respectively k 2 of the electromechanical coupling coefficient of the second surface acoustic wave resonator 4 k 2 (2) (1) = 0.0010, k 2 (2) = 0.00125 and k 2 (1) ≧ 0.0002 and k 2 (2) ≧ 0.0002, and the output of the surface acoustic wave resonator is sufficient Can be sized. Therefore, the sensitivity can be increased and the temperature can be measured with high accuracy. This will be described by showing TCF (ppm / ° C.), electromechanical coupling coefficient k 2, and power flow angle PFA (degrees) for surface acoustic wave resonators having various Euler angles.
　図４はθ＝４５°のときのＴＣＦ（ｐｐｍ／℃）と電気機械結合係数ｋ２のψに対する変化を示している。また、図５はθ＝４５°のときの伝播方向＝ψ＋ＰＦＡ（度）のψに対する変化を示している。例えば（０°，４５°，３５°）の場合、ψ＝３５°とＴＣＦを示す曲線との交点より、ＴＣＦ＝－２２ｐｐｍ／℃であることがわかり、ψ＝３５°とｋ２のグラフの交点より、ｋ２＝０．００１２５であることがわかる。このようにして図４より、ＴＣＦの絶対値が１０ｐｐｍ／℃以上で、それぞれ極性が異なっており、かつ電気機械結合係数をｋ２が０．０００２以上であるψの組み合わせをあげると、式（３）、式（４）の組み合わせであらわすことができる。 FIG. 4 shows changes in TCF (ppm / ° C.) and electromechanical coupling coefficient k 2 with respect to ψ when θ = 45 °. FIG. 5 shows the change of propagation direction = ψ + PFA (degrees) with respect to ψ when θ = 45 °. For example, in the case of (0 °, 45 °, 35 °), it can be seen from the intersection of ψ = 35 ° and the curve showing TCF that TCF = −22 ppm / ° C., and the graph of ψ = 35 ° and k 2 From the intersection, it can be seen that k 2 = 0.00125. From FIG. 4 this way, the absolute value of TCF in the 10 ppm / ° C. or higher, respectively have different polarities, and when the electromechanical coefficient k 2 is mentioned a combination of ψ is 0.0002 or more, the formula ( 3) It can be expressed by a combination of formula (4).
　第１のψ … ０°≦ψ≦２１° …式（３）
　第２のψ … ２８°≦ψ≦９０° …式（４） First ψ ... 0 ° ≤ ψ ≤ 21 ° ... Formula (3)
Second ψ ... 28 ° ≤ ψ ≤ 90 ° ... Formula (4)
　ただしこの組み合わせには、第１の弾性表面波共振子における弾性表面波の伝搬方向と、第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以上となる組み合わせも含まれる。そこで図５より、前記第１の弾性表面波共振子における弾性表面波の伝搬方向と、前記第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下となる組み合わせを明らかにする。図５の横軸はψ（度）、縦軸は伝播方向＝ψ＋ＰＦＡ（度）をあらわしている。例えば、式（３）であらわされる第１のψの範囲より（０°，４５°，５°）のときは表面波伝搬方向は１８．０°、式（４）であらわされる第２のψの範囲より（０°，４５°，３５°）のときは表面波伝搬方向は３１．５°となることを示している。この場合、伝播方向の差Ｄ（度）は１３．５°となり、従って、５０°以下を満足する組み合わせである。しかしながら、例えば、式（３）であらわされる第１のψの範囲より（０°，４５°，５°）のときは表面波伝搬方向は１８．０°、式（４）であらわされる第２のψの範囲より（０°，４５°，８５°）のときは表面波伝搬方向は８０．１°となることを示している。この場合、伝播方向の差Ｄ（度）は６２．１°となり、従って、５０°以下を満足しない組み合わせである。 However, in this combination, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or more. This combination is also included. Therefore, from FIG. 5, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less. Clarify the combination. The horizontal axis in FIG. 5 represents ψ (degrees), and the vertical axis represents propagation direction = ψ + PFA (degrees). For example, from the range of the first ψ expressed by the equation (3) (0 °, 45 °, 5 °), the surface wave propagation direction is 18.0 °, and the second ψ expressed by the equation (4). From the range of (0 °, 45 °, 35 °), the surface wave propagation direction is 31.5 °. In this case, the difference D (degree) in the propagation direction is 13.5 °, and thus the combination satisfies 50 ° or less. However, for example, in the case of (0 °, 45 °, 5 °) from the range of the first ψ expressed by the equation (3), the surface wave propagation direction is 18.0 °, and the second expressed by the equation (4). From the range of ψ of (0 °, 45 °, 85 °), the surface wave propagation direction is 80.1 °. In this case, the difference D (degree) in the propagation direction is 62.1 °, and therefore the combination does not satisfy 50 ° or less.
　このようにして、様々なオイラー角の弾性表面波共振子についてのレイリー波のＴＣＦ（ｐｐｍ／℃）、電気機械結合係数ｋ２及びパワーフロー角ＰＦＡ（度）を調査した。その結果、１）ＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、２）両者のＴＣＦの極性が異なっており、３）電気機械結合係数をｋ２が０．０００２以上であり、さらに４）第１の弾性表面波共振子における弾性表面波の伝搬方向と、第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下となる組み合わせを選んだ。その結果を表６～表８に示す。 In this way, the Rayleigh wave TCF (ppm / ° C.), the electromechanical coupling coefficient k 2, and the power flow angle PFA (degrees) of the surface acoustic wave resonators having various Euler angles were investigated. As a result, 1) the absolute value of TCF is 10 ppm / ° C. or higher, 2) the polarities of both TCFs are different, 3) the electromechanical coupling coefficient k 2 is 0.0002 or higher, and 4) The combination in which the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less was selected. The results are shown in Tables 6 to 8.
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000013
　この種の弾性表面波共振子の共振周波数を測定する回路の測定の精度は１ｐｐｍ程度である。温度測定に必要な精度は用途により様々であるが、例えば体温を測定する場合には０．１℃以下でなくてはならない。これより０．１℃を精度よく測定するためには１ｐｐｍ／０．１℃＝１０ｐｐｍ／℃以上のＴＣＦが必要であることがわかる。 The measurement accuracy of a circuit that measures the resonance frequency of this type of surface acoustic wave resonator is about 1 ppm. The accuracy required for temperature measurement varies depending on the application. For example, when measuring body temperature, it must be 0.1 ° C. or lower. From this, it can be seen that a TCF of 1 ppm / 0.1 ° C. = 10 ppm / ° C. or higher is necessary to accurately measure 0.1 ° C.
　なお、第１の実施形態において、図６はθ＝１０°のときのＴＣＦ（ｐｐｍ／℃）と電気機械結合係数ｋ２のψに対する変化を示している。また、図７はθ＝１０°のときの伝播方向＝ψ＋ＰＦＡ（度）のψに対する変化を示している。図６より、ＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、両者のＴＣＦの極性が異なっており、かつ電気機械結合係数ｋ２が０．０００２以上である、第１，第２のψの組み合わせをあげると、式（５）、式（６）の組み合わせで表わすことができる。 In the first embodiment, FIG. 6 shows changes in TCF (ppm / ° C.) and electromechanical coupling coefficient k 2 with respect to ψ when θ = 10 °. Further, FIG. 7 shows a change in propagation direction = ψ + PFA (degree) with respect to ψ when θ = 10 °. FIG. 6 shows that the first and second ψ combinations have an absolute value of TCF of 10 ppm / ° C. or more, both TCF polarities are different, and the electromechanical coupling coefficient k 2 is 0.0002 or more. Can be expressed by a combination of Formula (5) and Formula (6).
　第１のψ … ２９°≦ψ≦６５° …式（５）
　第２のψ … ７８°≦ψ≦８４° …式（６） First ψ ... 29 ° ≦ ψ ≦ 65 ° Formula (5)
Second ψ ... 78 ° ≤ ψ ≤ 84 ° ... Formula (6)
　ただし、この組み合わせには、第１の弾性表面波共振子における弾性表面波の伝搬方向と、第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以上となる組み合わせも含まれる。そこで図７より、前記第１の弾性表面波共振子における弾性表面波の伝搬方向と、前記第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下となる組み合わせを明らかにする。 However, in this combination, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or more. The combination which becomes is also included. Therefore, from FIG. 7, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less. Clarify the combination.
　図７の横軸はψ（度）、縦軸は伝播方向＝ψ＋ＰＦＡ（度）をあらわしている。例えば、式（５）であらわされる第１のψの範囲より（０°，１０°，３５°）のときは表面波伝搬方向は５９．２°、式（６）であらわされる第２のψの範囲より（０°，１０°，８０°）のときは表面波伝搬方向は６４．５°となることを示している。この場合、伝播方向の差Ｄ（度）は５．３°となり、従って、５０°以下を満足する組み合わせである。このようにして式（５）と式（６）の組合せのすべてにおいて伝播方向の差Ｄ（度）を確認すると、この場合には式（５）と式（６）であらわされる範囲すべてについて、５０度以下となることがわかる。 7, the horizontal axis represents ψ (degrees), and the vertical axis represents propagation direction = ψ + PFA (degrees). For example, in the range of the first ψ expressed by the equation (5) (0 °, 10 °, 35 °), the surface wave propagation direction is 59.2 °, and the second ψ expressed by the equation (6). From the range of (0 °, 10 °, 80 °), the surface wave propagation direction is 64.5 °. In this case, the difference D (degree) in the propagation direction is 5.3 °, and therefore the combination satisfies 50 ° or less. Thus, when the propagation direction difference D (degrees) is confirmed in all the combinations of the expressions (5) and (6), in this case, for all the ranges expressed by the expressions (5) and (6), It turns out that it becomes 50 degrees or less.
　このようにして、様々なオイラー角の弾性表面波共振子についての漏洩弾性表面波のＴＣＦ（ｐｐｍ／℃）、電気機械結合係数ｋ２及びパワーフロー角ＰＦＡ（度）を調査した。その結果、１）ＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、２）ＴＣＦの極性が異なっており、３）電気機械結合係数をｋ２が０．０００２以上であり、さらに４）第１の弾性表面波共振子における弾性表面波の伝搬方向と、第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下となる組み合わせを選んだ。結果を表９に示す。 Thus, the TCF (ppm / ° C.), electromechanical coupling coefficient k 2, and power flow angle PFA (degree) of the leaky surface acoustic wave for surface acoustic wave resonators having various Euler angles were investigated. As a result, 1) the absolute value of TCF is 10 ppm / ° C. or higher, 2) the polarity of TCF is different, 3) the electromechanical coupling coefficient is k 2 is 0.0002 or higher, and 4) the first A combination was selected in which the difference D (degree) between the propagation direction of the surface acoustic wave in the surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator was 50 ° or less. The results are shown in Table 9.
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000014
　（第１の実施形態の変形例）
　図８は、第１の実施形態の温度センサの他の変形例を示す模式的平面図である。本変形例の温度センサ３１では、図１に示した第１，第２の弾性表面波共振子３，４が接続電極指部３２により電気的に接続されて一体化されている。すなわち、図１に示したＩＤＴ電極８の第２のバスバー８ｃ、反射器９，１０の第２のバスバー９ｃ，１０ｃと、第２の弾性表面波共振子４のＩＤＴ電極５の第１のバスバー５ｂ、反射器６，７の第１のバスバー６ｂ，７ｂが省略されている。その代わり、例えば、ＩＤＴ電極８の第２のバスバー８ｃに接続されている電極指と、ＩＤＴ電極５の第１のバスバー５ｂに接続されている電極指とが接続電極指部３２により電気的に接続されている。反射器９，１０及び反射器６，７においても、同様に、接続電極指部３２により、省略されたバスバーに接続されている電極指同士が電気的に接続されている。 (Modification of the first embodiment)
FIG. 8 is a schematic plan view illustrating another modification of the temperature sensor according to the first embodiment. In the temperature sensor 31 of this modification, the first and second surface acoustic wave resonators 3 and 4 shown in FIG. 1 are electrically connected and integrated by a connection electrode finger 32. That is, the second bus bar 8c of the IDT electrode 8 shown in FIG. 1, the second bus bars 9c and 10c of the reflectors 9 and 10, and the first bus bar of the IDT electrode 5 of the second surface acoustic wave resonator 4 are shown. 5b and the first bus bars 6b and 7b of the reflectors 6 and 7 are omitted. Instead, for example, the electrode finger connected to the second bus bar 8 c of the IDT electrode 8 and the electrode finger connected to the first bus bar 5 b of the IDT electrode 5 are electrically connected by the connection electrode finger portion 32. It is connected. Similarly, in the reflectors 9 and 10 and the reflectors 6 and 7, the electrode fingers connected to the omitted bus bar are electrically connected by the connection electrode finger portions 32.
　本変形例のように、本発明における第１，第２の弾性表面波共振子は、複数の接続電極指部３２を用いて一体化されていてもよい。 As in this modification, the first and second surface acoustic wave resonators in the present invention may be integrated using a plurality of connection electrode fingers 32.
　上記第１の実施形態では、第１の弾性表面波共振子３及び第２の弾性表面波共振子４において励振されるレイリー波を利用した。しかしながら、本発明においては、第１，第２の弾性表面波共振子３，４において励振される漏洩弾性表面波を用いてもよい。 In the first embodiment, the Rayleigh wave excited in the first surface acoustic wave resonator 3 and the second surface acoustic wave resonator 4 is used. However, in the present invention, a leaky surface acoustic wave excited by the first and second surface acoustic wave resonators 3 and 4 may be used.
　（第２の実施形態）
　図９（ａ）は、本発明の第２の実施形態に係る温度センサを示す模式的平面図である。温度センサ４１は、水晶基板４２を有する。水晶基板４２のオイラー角は（０°，３５°，ψ）である。水晶基板４２上に、弾性表面波共振子４３が構成されている。弾性表面波共振子４３は、１つのＩＤＴ電極４４と、ＩＤＴ電極４４の両側に配置された反射器４５，４６とを有する。すなわち、１つのＩＤＴ電極４４と、ＩＤＴ電極４４の両側に配置された反射器４５，４６とからなる１つの１ポート型弾性表面波共振子が形成されている。 (Second Embodiment)
FIG. 9A is a schematic plan view showing a temperature sensor according to the second embodiment of the present invention. The temperature sensor 41 has a quartz substrate 42. The Euler angles of the quartz substrate 42 are (0 °, 35 °, ψ). A surface acoustic wave resonator 43 is formed on the quartz substrate 42. The surface acoustic wave resonator 43 includes one IDT electrode 44 and reflectors 45 and 46 disposed on both sides of the IDT electrode 44. That is, one 1-port surface acoustic wave resonator including one IDT electrode 44 and reflectors 45 and 46 disposed on both sides of the IDT electrode 44 is formed.
　本実施形態では、１つの弾性表面波共振子で、本発明の第１，第２の弾性表面波共振子が構成されている。 In the present embodiment, the first and second surface acoustic wave resonators of the present invention are constituted by one surface acoustic wave resonator.
　本実施形態では、ＩＤＴ電極４４により励振される弾性表面波のうち、レイリー波と、漏洩弾性表面波とが用いられる。すなわち、１つのＩＤＴ電極４４で励振される２つの弾性表面波を利用している。 In this embodiment, Rayleigh waves and leaky surface acoustic waves are used among the surface acoustic waves excited by the IDT electrode 44. That is, two surface acoustic waves excited by one IDT electrode 44 are used.
　ここでは、弾性表面波共振子４３のオイラー角は（０°，３５°，３０°）である。レイリー波のパワーフロー角ＰＦＡは－６．８°である。従って、レイリー波の伝搬方向は、３０°＋（－６．８°）＝２３．３°となる。 Here, the Euler angles of the surface acoustic wave resonators 43 are (0 °, 35 °, 30 °). The Rayleigh wave power flow angle PFA is −6.8 °. Therefore, the propagation direction of the Rayleigh wave is 30 ° + (− 6.8 °) = 23.3 °.
　他方、漏洩弾性表面波のパワーフロー角ＰＦＡは１２．２°である。従って、漏洩弾性表面波の伝搬方向は３０°＋１２．２°＝４２．２°である。 On the other hand, the power flow angle PFA of the leaky surface acoustic wave is 12.2 °. Accordingly, the propagation direction of the leaky surface acoustic wave is 30 ° + 12.2 ° = 42.2 °.
　上記のように、１つのＩＤＴ電極４４を有する弾性表面波共振子４３において、上記レイリー波による共振特性と、漏洩弾性表面波による共振特性を利用することができる。レイリー波の伝搬方向と漏洩弾性表面波の伝搬方向が上記のように異なっている。従って、ＩＤＴ電極４４では、異なる電位に接続されている電極指が交差している領域が平行四辺形の形状を有している。よって、バスバー４４ａ，４４ｂもまた、オイラー角のψ＝３０°方向から傾斜している。 As described above, in the surface acoustic wave resonator 43 having one IDT electrode 44, the resonance characteristic due to the Rayleigh wave and the resonance characteristic due to the leaky surface acoustic wave can be used. The propagation direction of the Rayleigh wave and the propagation direction of the leaky surface acoustic wave are different as described above. Therefore, in the IDT electrode 44, the region where the electrode fingers connected to different potentials intersect has a parallelogram shape. Accordingly, the bus bars 44a and 44b are also inclined from the Euler angle ψ = 30 ° direction.
　より具体的には、反射器４５側から反射器４６側に向かうにつれて、バスバー４４ａ，４４ｂがＸ軸方向側に移動している。それによって、上記レイリー波及び上記漏洩弾性表面波を確実に励振することが可能とされている。 More specifically, the bus bars 44a and 44b move to the X-axis direction side from the reflector 45 side toward the reflector 46 side. Accordingly, the Rayleigh wave and the leaky surface acoustic wave can be surely excited.
　また、反射器４５，４６は、伝搬方向が異なる上記レイリー波及び上記漏洩弾性表面波を反射し得るように構成されている。反射器４５を例にとると、ＩＤＴ電極４４側に位置している電極指の寸法に比べ、ＩＤＴ電極４４から遠い側の電極指の長さが長くされている。それによって、伝搬方向が異なるレイリー波及び漏洩弾性表面波を確実に反射することを可能としている。よって、反射器４５は、複数本の電極指及びバスバー４５ａ，４５ｂを含む形状の外形は、ＩＤＴ電極４４側を上底、反対側を下底とする台形形状とされている。反射器４６についても、反射器４５と同様に構成されている。 The reflectors 45 and 46 are configured to reflect the Rayleigh wave and the leaky surface acoustic wave having different propagation directions. Taking the reflector 45 as an example, the length of the electrode finger far from the IDT electrode 44 is made longer than the size of the electrode finger positioned on the IDT electrode 44 side. This makes it possible to reliably reflect Rayleigh waves and leaky surface acoustic waves having different propagation directions. Therefore, the reflector 45 has a trapezoidal shape with a plurality of electrode fingers and bus bars 45a and 45b, with the IDT electrode 44 side as an upper base and the opposite side as a lower base. The reflector 46 is configured in the same manner as the reflector 45.
　温度センサ４１のように、１つのＩＤＴ電極４４で、伝搬方向が異なる２つの弾性表面波を励振してもよく、この場合、温度センサ４１の小型化をさらに進めることができる。 As in the temperature sensor 41, two surface acoustic waves having different propagation directions may be excited by one IDT electrode 44. In this case, the temperature sensor 41 can be further reduced in size.
　本実施形態では、レイリー波を利用した場合の第１のオイラー角（０°，３５°，３０°）におけるＴＣＦは、後述の図１０に示すように－１６．８ｐｐｍ／℃であり、絶対値は１０ｐｐｍ／℃以上である。他方、第２のオイラー角も（０°，３５°，３０°）であるが、漏洩弾性表面波を利用しているので、そのＴＣＦは、後述の図１１に示すように３７．８ｐｐｍ／℃であり、その絶対値は１０ｐｐｍ／℃よりも大きい。このようにレイリー波による第１のオイラー角（０°，３５°，３０°）のＴＣＦと、漏洩弾性表面波を利用した第２のオイラー角（０°，３５°，３０°）のＴＣＦとは、上記の通り極性が異なっている。よって、両者のＴＣＦの差は５４．６ｐｐｍ／℃となり、本実施形態においても、－２０℃～１５０℃の温度を高精度に測定することができる。また、図１０および図１１から明らかなように、レイリー波の電気機械結合係数ｋ２は０．００１６０であり、漏洩弾性表面波の電気機械結合係数ｋ２は０．００１６１である。従って、温度センサ４１より充分大きな出力を取り出すことができる。 In the present embodiment, the TCF at the first Euler angles (0 °, 35 °, 30 °) when Rayleigh waves are used is −16.8 ppm / ° C. as shown in FIG. Is 10 ppm / ° C. or higher. On the other hand, the second Euler angle is also (0 °, 35 °, 30 °), but since the leaky surface acoustic wave is used, the TCF is 37.8 ppm / ° C. as shown in FIG. And its absolute value is greater than 10 ppm / ° C. In this way, the first Euler angles (0 °, 35 °, 30 °) TCF by Rayleigh waves, and the second Euler angles (0 °, 35 °, 30 °) TCF using leaky surface acoustic waves, Are different in polarity as described above. Therefore, the difference between the two TCFs is 54.6 ppm / ° C., and in this embodiment, a temperature of −20 ° C. to 150 ° C. can be measured with high accuracy. Moreover, as is clear from FIG. 10 and FIG. 11, the electromechanical coupling coefficient k 2 of the Rayleigh wave is 0.00160, the electromechanical coupling coefficient k 2 of the leaky surface acoustic wave is 0.00161. Therefore, an output sufficiently larger than that of the temperature sensor 41 can be taken out.
　第２の実施形態の温度センサ４１では、上記のように、レイリー波と漏洩弾性表面波とを１つのＩＤＴ電極４４により励振している。この場合においても、１つのＩＤＴ電極４４で励振されるレイリー波及び漏洩弾性表面波のＴＣＦの絶対値が１０ｐｐｍ／℃以上となり、両者の極性が異なるように、オイラー角を選択すればよい。すなわち、上記第２の実施形態の場合のオイラー角（０°，３５°，３０°）に限定されるものではない。このようなレイリー波と漏洩弾性表面波のオイラー角と、ＴＣＦ、電気機械結合係数ｋ２及びＰＦＡを下記の図１０～図１２を用いて説明する。 In the temperature sensor 41 of the second embodiment, the Rayleigh wave and the leaky surface acoustic wave are excited by one IDT electrode 44 as described above. Also in this case, the Euler angles may be selected so that the absolute values of TCFs of Rayleigh waves and leaky surface acoustic waves excited by one IDT electrode 44 are 10 ppm / ° C. or more and the polarities of the two are different. That is, it is not limited to the Euler angles (0 °, 35 °, 30 °) in the case of the second embodiment. Such Rayleigh wave and the Euler angles of the leaky surface acoustic wave will be described with reference TCF, the electromechanical coupling factor k 2 and PFA below to FIGS. 10 to 12.
　図１０は第１の弾性表面波共振子としてオイラー角（０°，３５°，３０°）のレイリー波のＴＣＦ（ｐｐｍ／℃）と電気機械結合係数ｋ２のψに対する変化を示す。また図１１には第２の弾性表面波共振子としてオイラー角（０°，３５°，３０°）の漏洩弾性表面波のＴＣＦ（ｐｐｍ／℃）と電気機械結合係数ｋ２のψに対する変化を示す。図１０および図１１において、レイリー波および漏洩弾性表面波のＴＣＦの絶対値がともに１０ｐｐｍ／℃以上で、それぞれ極性が異なっており、かつ電気機械結合係数をｋ２がともに０．０００２以上であるψは、式（７）、式（８）、式（９）で表すことができる。 Figure 10 is Euler angles (0 °, 35 °, 30 °) of the Rayleigh wave TCF and (ppm / ° C.) changes to the electromechanical coupling coefficient k 2 [psi shown as the first surface acoustic wave resonator. FIG. 11 also shows changes in TCF (ppm / ° C.) of the leaky surface acoustic wave having Euler angles (0 °, 35 °, 30 °) and the electromechanical coupling coefficient k 2 with respect to ψ as the second surface acoustic wave resonator. Show. 10 and FIG. 11, the absolute values of TCF of Rayleigh wave and leaky surface acoustic wave are both 10 ppm / ° C. or more, the polarities are different from each other, and the electromechanical coupling coefficient k 2 is both 0.0002 or more. ψ can be expressed by Expression (7), Expression (8), and Expression (9).
　８°≦ψ≦１５° …式（７）
　２５°≦ψ≦５３° …式（８）
　７５°≦ψ≦８３° …式（９） 8 ° ≦ ψ ≦ 15 ° (7)
25 ° ≦ ψ ≦ 53 ° Formula (8)
75 ° ≦ ψ ≦ 83 ° (9)
　ただし、この範囲では、第１の弾性表面波共振子における弾性表面波の伝搬方向と、第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以上となる場合も含まれる。そこで図１２より、前記第１の弾性表面波共振子における弾性表面波の伝搬方向と、前記第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下となる場合を明らかにする。 However, in this range, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or more. It is also included. Accordingly, from FIG. 12, the difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less. Clarify when.
　図１２の横軸はψ（度）、縦軸は伝播方向＝ψ＋ＰＦＡ（度）をあらわしている。例えば、式（７）であらわされる第１のψの範囲より（０°，３５°，１０°）のときは前記第１の弾性表面波共振子における弾性表面波の伝搬方向は４．１°、前記第２の弾性表面波共振子における弾性表面波の伝搬方向は２９．４°となることを示している。この場合、伝播方向の差Ｄ（度）は２５．３°となり、５０°以下を満足する。このようにして式（７）、式（８）、式（９）のすべてにおいて伝播方向の差Ｄ（度）を確認すると、この場合には式（７）、式（８）、式（９）であらわされる範囲すべてについて、５０度以下となることがわかる。 12, the horizontal axis represents ψ (degrees), and the vertical axis represents propagation direction = ψ + PFA (degrees). For example, in the case of (0 °, 35 °, 10 °) from the range of the first ψ expressed by Equation (7), the propagation direction of the surface acoustic wave in the first surface acoustic wave resonator is 4.1 °. The propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 29.4 °. In this case, the difference D (degree) in the propagation direction is 25.3 °, which satisfies 50 ° or less. Thus, when the propagation direction difference D (degree) is confirmed in all of the equations (7), (8), and (9), in this case, the equations (7), (8), and (9) It can be seen that it is 50 degrees or less for all of the range represented by.
　このようにして、様々なオイラー角の弾性表面波共振子についてのレイリー波および漏洩弾性表面波のＴＣＦ（ｐｐｍ／℃）、電気機械結合係数ｋ２及びパワーフロー角ＰＦＡ（度）を調査した。その結果、１）ＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、２）ＴＣＦの極性が異なっており、３）電気機械結合係数をｋ２が０．０００２以上であり、さらに４）第１の弾性表面波共振子における弾性表面波の伝搬方向と、第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下となるψを選んだ。その結果を表１０に示す。 In this manner, the Rayleigh wave and leaky surface acoustic wave TCF (ppm / ° C.), electromechanical coupling coefficient k 2, and power flow angle PFA (degree) were investigated for surface acoustic wave resonators having various Euler angles. As a result, 1) the absolute value of TCF is 10 ppm / ° C. or higher, 2) the polarity of TCF is different, 3) the electromechanical coupling coefficient is k 2 is 0.0002 or higher, and 4) the first Ψ was selected such that the difference D (degree) between the propagation direction of the surface acoustic wave in the surface acoustic wave resonator and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator was 50 ° or less. The results are shown in Table 10.
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000015
　第２の実施形態では、上記のように、レイリー波及び漏洩弾性表面波を反射し得るように第１及び第２の反射器４５，４６が設けられている。レイリー波及び漏洩弾性表面波を効率よく反射させるには、それぞれの伝搬方向において漏洩が生じ難いように反射器４５，４６を設けることが望ましい。 In the second embodiment, as described above, the first and second reflectors 45 and 46 are provided so as to reflect the Rayleigh wave and the leaky surface acoustic wave. In order to efficiently reflect the Rayleigh wave and the leaky surface acoustic wave, it is desirable to provide the reflectors 45 and 46 so that the leak does not easily occur in each propagation direction.
　従って、上記反射器４５，４６は以下のように設けられることが望ましい。図９（ｂ）において、ＩＤＴ電極４４のバスバー４４ｂに一端が接続されている複数本の電極指を第１の電極指とする。この複数本の第１の電極指の先端を結ぶ直線を第１仮想直線Ｗ１とする。バスバー４４ａに接続されている複数本の電極指を第２の電極指とする。この複数本の第２の電極指の先端を結ぶ直線を第２仮想直線Ｗ２とする。 Therefore, it is desirable to provide the reflectors 45 and 46 as follows. In FIG. 9B, a plurality of electrode fingers whose one ends are connected to the bus bar 44b of the IDT electrode 44 are defined as first electrode fingers. A straight line connecting the tips of the plurality of first electrode fingers is defined as a first virtual straight line W1. A plurality of electrode fingers connected to the bus bar 44a are defined as second electrode fingers. A straight line connecting the tips of the plurality of second electrode fingers is defined as a second virtual straight line W2.
　レイリー波の伝搬方向は第１，第２仮想直線Ｗ１，Ｗ２の延びる方向である。すなわち、レイリー波は、第１仮想直線Ｗ１と、第２仮想直線Ｗ２とで囲まれた領域を伝搬する。従って、第１，第２の反射器４５，４６の複数本の電極指が位置している部分内に、第１，第２仮想直線Ｗ１，Ｗ２で囲まれた領域が存在するように、第１，第２の反射器４５，４６が設けられることが望ましい。 The propagation direction of the Rayleigh wave is the direction in which the first and second virtual straight lines W1, W2 extend. That is, the Rayleigh wave propagates through a region surrounded by the first virtual straight line W1 and the second virtual straight line W2. Accordingly, the first and second reflectors 45 and 46 have a plurality of electrode fingers so that there is a region surrounded by the first and second virtual straight lines W1 and W2. 1 and 2nd reflectors 45 and 46 are preferably provided.
　また、第１仮想直線Ｗ１とＩＤＴ電極４４の第２の反射器４６側の最外側電極指との交点を通り、かつ漏洩弾性表面波伝搬方向と平行に延びる直線を第３仮想直線Ｗ３とする。第２仮想直線Ｗ２と、ＩＤＴ電極４４の第１の反射器４５側最外側電極指との交点を通り、かつ漏洩弾性表面波伝搬方向と平行に延びる直線を第４仮想直線Ｗ４とする。 A straight line passing through the intersection of the first virtual straight line W1 and the outermost electrode finger on the second reflector 46 side of the IDT electrode 44 and extending in parallel with the leaky surface acoustic wave propagation direction is defined as a third virtual straight line W3. . A straight line passing through the intersection of the second virtual straight line W2 and the outermost electrode finger on the first reflector 45 side of the IDT electrode 44 and extending in parallel with the leaky surface acoustic wave propagation direction is defined as a fourth virtual straight line W4.
　この場合、漏洩弾性表面波を確実に反射させるには、第３仮想直線Ｗ３と第４仮想直線Ｗ４とで囲まれた漏洩弾性表面波伝搬領域が、第１，第２の反射器４５，４６の電極指交差部分に位置していることが望ましい。従って、このように第１，第２の反射器４５，４６が設けられていることが望ましい。 In this case, in order to reliably reflect the leaky surface acoustic wave, the leaky surface acoustic wave propagation region surrounded by the third virtual straight line W3 and the fourth virtual straight line W4 is used as the first and second reflectors 45 and 46. It is desirable to be located at the electrode finger crossing portion. Therefore, it is desirable to provide the first and second reflectors 45 and 46 in this way.
　図９（ｂ）に示したように、この好ましい構造によれば、レイリー波と漏洩弾性表面波の双方を効率よく反射させることができる。従って、共振子のＱをより一層高めることができる。 As shown in FIG. 9B, according to this preferable structure, both the Rayleigh wave and the leaky surface acoustic wave can be efficiently reflected. Therefore, the Q of the resonator can be further increased.
　第２の実施形態では、上記のように、レイリー波及び漏洩弾性表面波を反射し得るように第１及び第２の反射器が設けられている。この構造を実現するには、好ましくは、反射器における電極指の延びる方向が、ＩＤＴ電極の電極指の延びる方向と平行であり、下記の式Ｈ＞Ｗ＋Ｌ×ＴａｎＤを満たすことが望ましい。ここで、図９（ａ）に示すように、Ｗ（単位はｍ）は、ＩＤＴ電極の電極指の交差幅を示す。Ｌは、反射器と、ＩＤＴ電極との最外側電極指同士間の中心間間隔（単位はｍ）である。Ｈは、第１及び第２の反射器の電極指の長さを示す。また、Ｄは、レイリー波の伝搬方向と漏洩弾性表面波の伝搬方向の差（単位は度）である。 In the second embodiment, as described above, the first and second reflectors are provided so as to reflect the Rayleigh wave and the leaky surface acoustic wave. In order to realize this structure, it is preferable that the extending direction of the electrode finger in the reflector is parallel to the extending direction of the electrode finger of the IDT electrode and satisfies the following formula H> W + L × TandD. Here, as shown in FIG. 9A, W (unit: m) indicates the crossing width of the electrode fingers of the IDT electrode. L is the center-to-center spacing (unit: m) between the outermost electrode fingers of the reflector and the IDT electrode. H indicates the length of the electrode fingers of the first and second reflectors. D is the difference (in degrees) between the propagation direction of the Rayleigh wave and the propagation direction of the leaky surface acoustic wave.
　（オイラー角の許容範囲）
　本発明に係る温度センサでは、第１及び第２のオイラー角の組み合わせは、上述した表６～８、表９または表１０の組み合わせであることが望ましい。ここでは、オイラー角（φ，θ，ψ）において、φ及びθは例えば０°±３°あるいは４０°±３°のように、±３°範囲の幅を有する。このように、オイラー角のφ及びθは、上述した表の好ましい組み合わせにおいて、±３°の範囲内であれば、上述した実施形態と同様に、ＴＣＦの絶対値をほぼ１０ｐｐｍ／℃以上とし、第１，第２のオイラー角におけるＴＣＦの極性を異ならせることができる。これを、オイラー角が（０°，４５°，０°）およびオイラー角が（０°，４５°，５°）であるレイリー波を利用した場合を例にとり説明する。 (Euler angle tolerance)
In the temperature sensor according to the present invention, the combination of the first and second Euler angles is preferably the combination of Tables 6 to 8, Table 9 or Table 10 described above. Here, in Euler angles (φ, θ, ψ), φ and θ have a width in the range of ± 3 °, for example, 0 ° ± 3 ° or 40 ° ± 3 °. Thus, if the Euler angles φ and θ are within a range of ± 3 ° in the preferred combinations of the above-described tables, the absolute value of TCF is set to approximately 10 ppm / ° C. or more, as in the above-described embodiment, The polarities of the TCF at the first and second Euler angles can be made different. This will be described using an example in which a Rayleigh wave having an Euler angle of (0 °, 45 °, 0 °) and an Euler angle of (0 °, 45 °, 5 °) is used.
　表１１及び表１２は、それぞれ、レイリー波を利用した場合であって、オイラー角（０°，θ，０°）または（（０°，θ，５°）の場合のθとＴＣＦとの関係を示す。また、表１１及び表１２では、θがθ－３°またはθ＋３°の場合のＴＣＦの変化値を併せて示す。 Tables 11 and 12 show the relationship between θ and TCF when Rayleigh waves are used, respectively, when Euler angles (0 °, θ, 0 °) or ((0 °, θ, 5 °)) are used. Tables 11 and 12 also show TCF change values when θ is θ-3 ° or θ + 3 °.
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000017
Figure JPOXMLDOC01-appb-T000017
　表１１から明らかなように、（０°，θ，０°）において、θが４０°～５０°の範囲において、θが－３°あるいは＋３°変化してもＴＣＦの変化は－１．９～＋２．４ｐｐｍ／℃と非常に小さいことがわかる。 As is apparent from Table 11, at (0 °, θ, 0 °), when θ is in the range of 40 ° to 50 °, even if θ changes by −3 ° or + 3 °, the change in TCF is −1.9. It can be seen that it is very small, up to +2.4 ppm / ° C.
　同様に、表１２から明らかなように、（０°，θ，５°）において、θが４０°～５５°の範囲で、θが－３°または＋３°変動したとしても、ＴＣＦの変化分は－０．７～＋２．４ｐｐｍ／℃と非常に小さいことがわかる。よって、レイリー波を利用した場合、θが、表に記載の角度±３°の範囲であっても、ＴＣＦの絶対値をほぼ１０ｐｐｍ／℃以上と大きくすることができることがわかる。 Similarly, as is clear from Table 12, even when θ is in the range of 40 ° to 55 ° and θ varies by −3 ° or + 3 ° at (0 °, θ, 5 °), the amount of change in TCF It can be seen that is as small as −0.7 to +2.4 ppm / ° C. Therefore, it can be seen that when Rayleigh waves are used, the absolute value of TCF can be increased to approximately 10 ppm / ° C. or more even when θ is in the range of the angle ± 3 ° described in the table.
　表１３は、漏洩弾性表面波を利用した場合であって、オイラー角が（０°，θ，３０°）の場合のθとＴＣＦとの関係を示す。また、表１３では、θがθ－３°またはθ＋３°の場合のＴＣＦの変化値を併せて示す。 Table 13 shows the relationship between θ and TCF when a leaky surface acoustic wave is used and the Euler angles are (0 °, θ, 30 °). Table 13 also shows the change in TCF when θ is θ-3 ° or θ + 3 °.
Figure JPOXMLDOC01-appb-T000018
Figure JPOXMLDOC01-appb-T000018
　表１３から明らかなように、漏洩弾性表面波を用いた場合においても、（０°，θ，３０°）において、θが３０°～４０°の範囲において、θが－３°あるいは＋３°の変化をしてもＴＣＦの変化は－１．５～＋１．８ｐｐｍ／℃と非常に小さいことがわかる。 As is apparent from Table 13, even when leaky surface acoustic waves are used, at (0 °, θ, 30 °), when θ is in the range of 30 ° to 40 °, θ is −3 ° or + 3 °. It can be seen that the change in TCF is very small, -1.5 to +1.8 ppm / ° C.
　表１４及び表１５は、それぞれ、漏洩弾性表面波を利用した場合であって、オイラー角が（０°，θ，７５°）または（０°，θ，８０°）の場合のθとＴＣＦとの関係を示す。また、表１４及び表１５では、θがθ－３°またはθ＋３°の場合のＴＣＦの変化値を併せて示す。 Tables 14 and 15 show the case where leaky surface acoustic waves are used, and θ and TCF when the Euler angles are (0 °, θ, 75 °) or (0 °, θ, 80 °). The relationship is shown. Tables 14 and 15 also show TCF change values when θ is θ-3 ° or θ + 3 °.
Figure JPOXMLDOC01-appb-T000019
Figure JPOXMLDOC01-appb-T000019
Figure JPOXMLDOC01-appb-T000020
Figure JPOXMLDOC01-appb-T000020
　表１４から明らかなように、漏洩弾性表面波を用いた場合において、（０°，θ，７５°）において、θが３０°～４０°の範囲において、θが－３°あるいは＋３°の変化をしてもＴＣＦの変化は－２．８～＋０．７ｐｐｍ／℃と非常に小さいことがわかる。また、ＴＣＦは、絶対値１４．０ｐｐｍ／℃よりも大きい方向に変化することもわかる。 As is apparent from Table 14, when leaky surface acoustic waves are used, the change of θ is −3 ° or + 3 ° in the range of 30 ° to 40 ° at (0 °, θ, 75 °). It can be seen that the change in TCF is very small, -2.8 to +0.7 ppm / ° C. It can also be seen that TCF changes in a direction larger than the absolute value of 14.0 ppm / ° C.
　表１５から明らかなように、漏洩弾性表面波を用いた場合において、（０°，θ，８０°）において、θが３０°～４０°の範囲において、θが－３°あるいは＋３°の変化をしてもＴＣＦの変化は－３．６～＋２．８ｐｐｍ／℃と小さいことがわかる。 As is apparent from Table 15, when leaky surface acoustic waves are used, when (0 °, θ, 80 °), θ is in the range of 30 ° to 40 °, and θ is changed by −3 ° or + 3 °. It can be seen that the change in TCF is as small as −3.6 to +2.8 ppm / ° C. even if.
　従って、漏洩弾性表面波を用いた場合においても、同様に、θの値が±３°変動してもよいことがわかる。 Therefore, it can be seen that the value of θ may fluctuate ± 3 ° in the same manner even when a leaky surface acoustic wave is used.
　同様に、他の好ましいオイラー角の場合も、θは、±３°の範囲で変動しても、上記と同様にＴＣＦの絶対値を１０ｐｐｍ／℃以上とすることができる。 Similarly, in the case of other preferable Euler angles, even if θ varies within a range of ± 3 °, the absolute value of TCF can be made 10 ppm / ° C. or more in the same manner as described above.
　また、オイラー角のφについても、同様である。 The same applies to the Euler angle φ.
　本発明に係る温度センサは前記第１の弾性表面波共振子の周波数Ｆ１と、前記第２の弾性表面波共振子の周波数Ｆ２の周波数の差を測定している。例えば、弾性表面波共振子の周波数を共振子の反射特性（Ｓ１１）の極小値として検出する場合について述べる。図１３に図８で示した共振子の反射特性（Ｓ１１）の周波数依存性を示す。この場合の温度をＴ１とすると、温度Ｔ１では前記第１の弾性表面波共振子の周波数Ｆ１と、前記第２の弾性表面波共振子の周波数Ｆ２の周波数の差が十分に大きい。従って、それぞれの共振子の周波数Ｆ１およびＦ２を、それぞれの反射特性（Ｓ１１）の極小値として検出することが可能である。 The temperature sensor according to the present invention measures the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator. For example, a case where the frequency of the surface acoustic wave resonator is detected as the minimum value of the reflection characteristic (S11) of the resonator will be described. FIG. 13 shows the frequency dependence of the reflection characteristic (S11) of the resonator shown in FIG. If the temperature in this case is T1, the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator is sufficiently large at the temperature T1. Therefore, it is possible to detect the frequencies F1 and F2 of the respective resonators as the minimum values of the respective reflection characteristics (S11).
　次に、図１４は、温度を測定することができない場合の反射特性を示す図である。例えば、温度がＴ１からＴ１とは異なる温度Ｔ２に変化した場合、反射特性Ｓ１１は図１４に示す通りとなる。この場合、第１の弾性表面波共振子の周波数Ｆ１と、前記第２の弾性表面波共振子の周波数Ｆ２の周波数の差が小さくなる。従って、第１，第２の共振子の周波数Ｆ１およびＦ２を、反射特性（Ｓ１１）の極小値として検出することが不可能になる場合を図１４に示す。 Next, FIG. 14 is a diagram showing the reflection characteristics when the temperature cannot be measured. For example, when the temperature changes from T1 to a temperature T2 different from T1, the reflection characteristic S11 is as shown in FIG. In this case, the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator is reduced. Accordingly, FIG. 14 shows a case where it is impossible to detect the frequencies F1 and F2 of the first and second resonators as the minimum value of the reflection characteristic (S11).
　図１４に示す場合には、前記第１の弾性表面波共振子の周波数Ｆ１は特定できるが、前記第２の弾性表面波共振子の周波数Ｆ２は極小値がなく、特定することができない。この場合には前記第１の弾性表面波共振子の周波数Ｆ１と、前記第２の弾性表面波共振子の周波数Ｆ２の周波数の差を測定すること、つまり温度を測定することができない。そのため当該温度センサが使用される温度範囲、例えば体温測定の場合は３０℃から４５℃の範囲において、前記第１の弾性表面波共振子の周波数Ｆ１と、前記第２の弾性表面波共振子の周波数Ｆ２の周波数の差を十分に大きくすることが必要である。例えば第１の弾性表面波共振子の電極指ピッチと、第２の弾性表面波共振子の電極指ピッチを周波数Ｆ１と周波数Ｆ２の差が十分に大きくなるように異ならせることなどが必要である。 In the case shown in FIG. 14, the frequency F1 of the first surface acoustic wave resonator can be specified, but the frequency F2 of the second surface acoustic wave resonator has no minimum value and cannot be specified. In this case, the difference between the frequency F1 of the first surface acoustic wave resonator and the frequency F2 of the second surface acoustic wave resonator cannot be measured, that is, the temperature cannot be measured. Therefore, in the temperature range in which the temperature sensor is used, for example, in the range of 30 ° C. to 45 ° C. in the case of body temperature measurement, the frequency F1 of the first surface acoustic wave resonator and the second surface acoustic wave resonator are It is necessary to sufficiently increase the frequency difference of the frequency F2. For example, it is necessary to make the electrode finger pitch of the first surface acoustic wave resonator different from the electrode finger pitch of the second surface acoustic wave resonator so that the difference between the frequency F1 and the frequency F2 is sufficiently large. .
　しかしながら、前記周波数Ｆ１と、前記周波数Ｆ２の周波数との差が大きすぎると検出回路が複雑になる。そのため前記周波数Ｆ１と、前記周波数Ｆ２との周波数の差を式（２）で示すΔＦ以上とすることが望ましい。それによって、検出回路を複雑化せず、かつ前記周波数Ｆ１と、前記周波数Ｆ２との周波数の差が十分に大きくすることができる。よって、周波数Ｆ１およびＦ２を、第１，第２の弾性表面波共振子の反射特性（Ｓ１１）の最小値として検出することが可能となる。その結果、温度を高精度に測定することが可能となる。 However, if the difference between the frequency F1 and the frequency F2 is too large, the detection circuit becomes complicated. Therefore, it is desirable that the frequency difference between the frequency F1 and the frequency F2 be equal to or greater than ΔF represented by the equation (2). Thereby, the detection circuit is not complicated, and the frequency difference between the frequency F1 and the frequency F2 can be sufficiently increased. Therefore, the frequencies F1 and F2 can be detected as the minimum value of the reflection characteristics (S11) of the first and second surface acoustic wave resonators. As a result, the temperature can be measured with high accuracy.
　ΔＦ=１／５×Ｆ１／（Ｆ１ｈ－Ｆ１ｌ）＋１／５×Ｆ２／（Ｆ２ｈ－Ｆ２ｌ） ・・・式（２） ΔF = 1/5 × F1 / (F1h−F1l) + 1/5 × F2 / (F2h−F2l) Equation (2)
　なお、式（２）中Ｆ１ｈはＦ１における強度の１／√２の強度となる２つの周波数の内、高い方の周波数であり、Ｆ１ｌはＦ１における強度の１／√２の強度となる２つの周波数の内、高い方の周波数を示す。また、Ｆ２ｈはＦ２における強度の１／√２の強度となる２つの周波数の内、高い方の周波数であり、Ｆ２ｌはＦ２における強度の１／√２の強度となる２つの周波数の内、高い方の周波数を示す。また、式（２）の右辺の各係数１／５は実験的に求められた値である。 In Formula (2), F1h is the higher frequency of the two frequencies that are 1 / √2 of the intensity in F1, and F1l is the two frequencies that are 1 / √2 of the intensity in F1. The higher frequency is shown. F2h is the higher frequency of the two frequencies that are 1 / √2 of the intensity in F2, and F2l is the higher of the two frequencies that are 1 / √2 of the intensity in F2. Indicates the frequency. In addition, each coefficient 1/5 on the right side of Equation (2) is a value obtained experimentally.
　これらの関係を図示したものが図１５である。 FIG. 15 illustrates these relationships.
　なお、上記では、φは０°～１８０°、ψは０°～９０°の範囲でのみ記述しているが、水晶の結晶の対称性より
　θ(１８０°+Ｘ°)= θ(Ｘ°)
　ψ(９０°+Ｘ°)=ψ（９０°-Ｘ°）
　ψ(１８０°+Ｘ°)=ψ（Ｘ°）
であることは明白である。 In the above, φ is described only in the range of 0 ° to 180 °, and ψ is described in the range of 0 ° to 90 °, but θ (180 ° + X °) = θ (X ° )
ψ (90 ° + X °) = ψ (90 ° -X °)
ψ (180 ° + X °) = ψ (X °)
It is clear that.
　例えば、
　θ(２００°)= θ(２０°)
　ψ(１１０°)=ψ（２０°）
　ψ(２００°)=ψ（２０°）
である。 For example,
θ (200 °) = θ (20 °)
ψ (110 °) = ψ (20 °)
ψ (200 °) = ψ (20 °)
It is.
　　１…温度センサ
　　２…水晶基板
　　３，４…第１，第２の弾性表面波共振子
　　５…第１のＩＤＴ電極
　　５ｂ，５ｃ…バスバー
　　６，７…反射器
　　６ｂ，６ｃ，７ｂ，７ｃ…バスバー
　　８…第２のＩＤＴ電極
　　８ｂ，８ｃ…バスバー
　　９，１０…反射器
　　９ｂ，９ｃ，１０ｂ，１０ｃ…バスバー
　　３１…温度センサ
　　３２…接続電極指部
　　４１…温度センサ
　　４２…水晶基板
　　４３…弾性表面波共振子
　　４４…ＩＤＴ電極
　　４４ａ，４４ｂ…バスバー
　　４５，４６…反射器
　　４５ａ，４５ｂ…バスバー
　　Ｗ１～Ｗ４…第1～第４仮想直線
  DESCRIPTION OF SYMBOLS 1 ... Temperature sensor 2 ... Quartz substrate 3, 4 ... 1st, 2nd surface acoustic wave resonator 5 ... 1st IDT electrode 5b, 5c ... Bus bar 6, 7 ... Reflector 6b, 6c, 7b, 7c ... Bus bar 8 ... 2nd IDT electrode 8b, 8c ... Bus bar 9, 10 ... Reflector 9b, 9c, 10b, 10c ... Bus bar 31 ... Temperature sensor 32 ... Connection electrode finger part 41 ... Temperature sensor 42 ... Quartz substrate 43 ... Surface acoustic wave Resonator 44 ... IDT electrodes 44a and 44b ... Bus bars 45 and 46 ... Reflectors 45a and 45b ... Bus bars W1 to W4 ... First to fourth virtual straight lines

Claims (8)

  1. 　－２０℃～１５０℃の範囲内の温度を測定するための温度センサであって、
    　水晶基板と、
    　前記水晶基板上に構成された第１の弾性表面波共振子と、
    　前記水晶基板上に構成されている第２の弾性表面波共振子とを備え、
    　前記第１及び第２の弾性表面波共振子の－２０℃～１５０℃における周波数温度係数を下記の式で示されるＴＣＦとしたときに、第１及び第２の弾性表面波共振子のＴＣＦの絶対値が１０ｐｐｍ／℃以上であり、かつ第１の弾性表面波共振子のＴＣＦと、第２の弾性表面波共振子のＴＣＦの極性が異なっており、かつ前記第１の弾性表面波共振子における弾性表面波の伝搬方向と、前記第２の弾性表面波共振子における弾性表面波の伝搬方向との差Ｄ（度）が５０°以下であり、かつ前記第１の弾性表面波共振子の電気機械結合係数をｋ２（１）、前記第２の共振子の電気機械結合係数をｋ２（２）としたときに、ｋ２（１）≧０．０００２かつｋ２（２）≧０．０００２である、温度センサ。
    　ＴＣＦ＝Ｖ－１（３５℃）×［（Ｖ（１５０℃）－Ｖ（－２０℃））／１７０℃］－ＬＥＣ　…式（１）
    　なお、式（１）中、Ｖは音速（ｍ／秒）を示し、Ｖ－１（３５℃）は、３５℃における音速の逆数を意味し、Ｖ（１５０℃）及びＶ（－２０℃）は、それぞれ、１５０℃及び－２０℃における音速（ｍ／秒）を示し、ＬＥＣは水晶基板の線膨張係数（単位は１／℃）を示す。     A temperature sensor for measuring a temperature within a range of −20 ° C. to 150 ° C.,
    A quartz substrate,
    A first surface acoustic wave resonator configured on the quartz substrate;
    A second surface acoustic wave resonator configured on the quartz substrate,
    When the frequency temperature coefficient at −20 ° C. to 150 ° C. of the first and second surface acoustic wave resonators is TCF represented by the following formula, the TCF of the first and second surface acoustic wave resonators is The absolute value is 10 ppm / ° C. or more, the TCF of the first surface acoustic wave resonator and the TCF of the second surface acoustic wave resonator are different, and the first surface acoustic wave resonator The difference D (degree) between the propagation direction of the surface acoustic wave in the first surface acoustic wave and the propagation direction of the surface acoustic wave in the second surface acoustic wave resonator is 50 ° or less, and the first surface acoustic wave resonator has When the electromechanical coupling coefficient is k 2 (1) and the electromechanical coupling coefficient of the second resonator is k 2 (2), k 2 (1) ≧ 0.0002 and k 2 (2) ≧ 0 .0002, a temperature sensor.
    TCF = V −1 (35 ° C.) × [(V (150 ° C.) − V (−20 ° C.)) / 170 ° C.] − LEC Formula (1)
    In the formula (1), V represents the speed of sound (m / sec), V −1 (35 ° C.) means the reciprocal of the sound speed at 35 ° C., and V (150 ° C.) and V (−20 ° C.) Represents the sound velocity (m / sec) at 150 ° C. and −20 ° C., respectively, and LEC represents the linear expansion coefficient (unit: 1 / ° C.) of the quartz substrate.
  2. 　第１及び第２の弾性表面波共振子において、弾性表面波としてレイリー波を利用しており、前記第１及び第２の弾性表面波共振子における水晶基板のオイラー角を、それぞれ、第１のオイラー角（φ，θ，ψ１）及び第２のオイラー角（φ，θ，ψ２）としたとき、第１のオイラー角と第２のオイラー角とが、下記の表１～３に示す何れかの組み合わせを満たす、請求項１に記載の温度センサ。
    Figure JPOXMLDOC01-appb-T000001
    Figure JPOXMLDOC01-appb-T000002
    Figure JPOXMLDOC01-appb-T000003
         In the first and second surface acoustic wave resonators, Rayleigh waves are used as the surface acoustic waves, and the Euler angles of the quartz crystal substrates in the first and second surface acoustic wave resonators are respectively When the Euler angles (φ, θ, ψ1) and the second Euler angles (φ, θ, ψ2) are set, the first Euler angles and the second Euler angles are any of those shown in Tables 1 to 3 below. The temperature sensor according to claim 1 satisfying a combination of:
    Figure JPOXMLDOC01-appb-T000001
    Figure JPOXMLDOC01-appb-T000002
    Figure JPOXMLDOC01-appb-T000003
  3. 　第１及び第２の弾性表面波共振子において、弾性表面波として漏洩弾性表面波を利用しており、前記第１及び第２の弾性表面波共振子における水晶基板のオイラー角を、それぞれ、第１のオイラー角（φ，θ，ψ１）及び第２のオイラー角（φ，θ，ψ２）としたとき、第１のオイラー角と第２のオイラー角とが、下記の表４に示す何れかの組み合わせを満たす、請求項１に記載の温度センサ。
    Figure JPOXMLDOC01-appb-T000004
         In the first and second surface acoustic wave resonators, a leaky surface acoustic wave is used as the surface acoustic wave, and the Euler angles of the quartz crystal substrates in the first and second surface acoustic wave resonators are respectively When the Euler angles (φ, θ, ψ1) of 1 and the second Euler angles (φ, θ, ψ2) are set, the first Euler angle and the second Euler angle are any of those shown in Table 4 below. The temperature sensor according to claim 1 satisfying a combination of:
    Figure JPOXMLDOC01-appb-T000004
  4. 　前記第１の表面波共振子において、弾性表面波としてレイリー波を利用しており、前記第２の弾性表面波共振子において弾性表面波として漏洩弾性表面波を利用しており、前記第１及び第２の弾性表面波共振子における前記水晶基板のオイラー角が、下記の表５に示す何れかの範囲である、請求項１に記載の温度センサ。
    Figure JPOXMLDOC01-appb-T000005
         In the first surface acoustic wave resonator, a Rayleigh wave is used as the surface acoustic wave, and in the second surface acoustic wave resonator, a leaky surface acoustic wave is used as the surface acoustic wave. The temperature sensor according to claim 1, wherein an Euler angle of the quartz crystal substrate in the second surface acoustic wave resonator is in any range shown in Table 5 below.
    Figure JPOXMLDOC01-appb-T000005
  5. 　前記第１の弾性表面波共振子が第１のＩＤＴ電極と、第１のＩＤＴ電極の弾性表面波伝搬方向両側に配置された反射器とを有し、
    　前記第２の弾性表面波共振子が、ＩＤＴ電極と、ＩＤＴ電極の弾性表面波伝搬方向両側に配置された反射器とを有する、請求項１～４のいずれか１項に記載の温度センサ。     The first surface acoustic wave resonator includes a first IDT electrode and reflectors disposed on both sides of the surface acoustic wave propagation direction of the first IDT electrode;
    5. The temperature sensor according to claim 1, wherein the second surface acoustic wave resonator includes an IDT electrode and reflectors disposed on both sides of the IDT electrode in the surface acoustic wave propagation direction.
  6. 　前記水晶基板上に１つのＩＤＴ電極と、該ＩＤＴ電極の両側に配置されており、かつそれぞれが複数本の電極指を有する第１及び第２の反射器とが設けられており、前記ＩＤＴ電極及び第１及び第２の反射器により、レイリー波を利用した前記第１の弾性表面波共振子と、漏洩弾性表面波を用いた第２の弾性表面波共振子とが構成されており、
    　前記ＩＤＴ電極が互いの電極指が間挿されるように配置された第１，第２のくし歯電極を有し、前記第１，第２のくし歯電極において電極指の先端を結ぶ線を第１、第２仮想直線とし、
    　前記第１、第２仮想直線がレイリー波伝搬方向と平行であり、
    　第１仮想直線と前記ＩＤＴ電極の第２反射器側最外電極指との交点を通り、かつＬＳＡＷ伝搬方向に平行に延びる直線を第３仮想直線とし、
    　第２仮想直線と、前記ＩＤＴ電極の第１反射器側最外電極指との交点を通りかつＬＳＡＷ伝搬方向に平行に延びる直線を第４仮想直線としたときに、
    　第１反射器の電極指の一端が第１仮想直線上に、他端が第４仮想直線上に位置しており、
    　第２反射器の電極指の一端が第３仮想直線上に、他端が第２仮想直線上に位置しており、
    　前記第１及び第２の反射器の複数本の前記電極指が、それぞれ、前記レイリー波及び前記漏洩弾性表面波を反射するように構成される、請求項４に記載の温度センサ。     One IDT electrode on the quartz substrate, and first and second reflectors that are arranged on both sides of the IDT electrode and each have a plurality of electrode fingers, are provided. And the first and second reflectors constitute the first surface acoustic wave resonator using a Rayleigh wave and the second surface acoustic wave resonator using a leaky surface acoustic wave,
    The IDT electrode has first and second comb electrodes arranged so that the electrode fingers of each other are inserted, and a line connecting the tips of the electrode fingers in the first and second comb electrodes is 1 and the second virtual straight line,
    The first and second virtual lines are parallel to the Rayleigh wave propagation direction;
    A straight line passing through the intersection of the first virtual straight line and the outermost electrode finger of the IDT electrode on the second reflector side and extending in parallel with the LSAW propagation direction is defined as a third virtual straight line,
    When a straight line extending through the intersection of the second virtual straight line and the first reflector side outermost electrode finger of the IDT electrode and extending in parallel with the LSAW propagation direction is defined as a fourth virtual straight line,
    One end of the electrode finger of the first reflector is located on the first imaginary line and the other end is located on the fourth imaginary line,
    One end of the electrode finger of the second reflector is located on the third virtual line, and the other end is located on the second virtual line,
    The temperature sensor according to claim 4, wherein the plurality of electrode fingers of the first and second reflectors are configured to reflect the Rayleigh wave and the leaky surface acoustic wave, respectively.
  7. 　前記第１，第２の反射器の電極指の延びる方向が、前記ＩＤＴ電極の前記電極指の延びる方向と平行であり、前記ＩＤＴ電極の前記電極指の交叉幅をＷ（単位はｍ）、前記第１及び第２の反射器と、前記ＩＤＴ電極の最外側電極指同士間の間隔をＬ（単位はｍ）、前記第１及び第２の反射器の前記電極指の長さをＨ（単位はｍ）、前記レイリー波と前記漏洩弾性表面波の伝搬方向の差をＤ（度）としたときに、Ｈ＞Ｗ＋Ｌ×ｔａｎＤとされている、請求項６に記載の温度センサ。 The extending direction of the electrode fingers of the first and second reflectors is parallel to the extending direction of the electrode fingers of the IDT electrode, and the crossing width of the electrode fingers of the IDT electrode is W (unit is m). The distance between the first and second reflectors and the outermost electrode fingers of the IDT electrode is L (unit is m), and the length of the electrode fingers of the first and second reflectors is H ( The temperature sensor according to claim 6, wherein the unit is m), and H> W + L × tanD, where D (degrees) is a difference in propagation direction between the Rayleigh wave and the leaky surface acoustic wave.
  8. 　前記温度センサが使用される温度範囲において、前記第１の弾性表面波共振子の共振周波数Ｆ１と、前記第２の弾性表面波共振子の共振周波数Ｆ２とが、式（２）で示すΔＦ以上離れているように構成されている、請求項１～７のいずれか１項に記載の温度センサ。
    　ΔＦ=１／５×Ｆ１／（Ｆ１ｈ－Ｆ１ｌ）＋１／５×Ｆ２／（Ｆ２ｈ－Ｆ２ｌ） ・・・式（２）
    　なお、式（２）中Ｆ１ｈはＦ１における振幅強度の１／√２の強度となる周波数の内、高い方の周波数であり、Ｆ１ｌはＦ１における振幅強度の１／√２の強度となる周波数の内、低い方の周波数を示す。また、Ｆ２ｈはＦ２における振幅強度の１／√２の強度となる周波数の内、高い方の周波数であり、Ｆ２ｌはＦ２における振幅強度の１／√２の強度となる周波数の内、低い方の周波数を示す。     In a temperature range in which the temperature sensor is used, a resonance frequency F1 of the first surface acoustic wave resonator and a resonance frequency F2 of the second surface acoustic wave resonator are greater than or equal to ΔF represented by Expression (2). The temperature sensor according to any one of claims 1 to 7, wherein the temperature sensor is configured to be separated from each other.
    ΔF = 1/5 × F1 / (F1h−F1l) + 1/5 × F2 / (F2h−F2l) (2)
    In Formula (2), F1h is a higher frequency among the frequencies that are 1 / √2 of the amplitude intensity in F1, and F1l is a frequency that is 1 / √2 of the amplitude intensity in F1. Of these, the lower frequency is shown. F2h is a higher frequency among the frequencies that are 1 / √2 of the amplitude intensity in F2, and F2l is a lower frequency among the frequencies that are 1 / √2 of the amplitude intensity in F2. Indicates the frequency.
PCT/JP2011/060835 2010-05-13 2011-05-11 Temperature sensor WO2011142380A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2012514817A JP5527410B2 (en) 2010-05-13 2011-05-11 Temperature sensor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2010-110929 2010-05-13
JP2010110929 2010-05-13

Publications (1)

Publication Number Publication Date
WO2011142380A1 true WO2011142380A1 (en) 2011-11-17

Family

ID=44914432

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2011/060835 WO2011142380A1 (en) 2010-05-13 2011-05-11 Temperature sensor

Country Status (2)

Country Link
JP (1) JP5527410B2 (en)
WO (1) WO2011142380A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015064238A1 (en) * 2013-10-31 2015-05-07 京セラ株式会社 Elastic wave element, filter element and communication device
CN106225948A (en) * 2016-07-27 2016-12-14 电子科技大学 A kind of double SAW Temperature Sensors and method for designing thereof
JP2021516906A (en) * 2018-03-16 2021-07-08 フレクエンシスＦｒｅｃ’Ｎ’Ｓｙｓ Composite substrate for SAW tags for RFID and sensor applications
CN114112102A (en) * 2021-11-24 2022-03-01 之江实验室 Surface acoustic wave temperature sensor with linear output characteristic and preparation method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6140021U (en) * 1984-08-14 1986-03-13 日本無線株式会社 surface acoustic wave oscillator
WO2001042752A1 (en) * 1999-12-10 2001-06-14 Fujitsu Limited Temperature sensor
WO2006123085A1 (en) * 2005-05-20 2006-11-23 Transense Technologies Plc Saw torque and temperature sensor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6140021U (en) * 1984-08-14 1986-03-13 日本無線株式会社 surface acoustic wave oscillator
WO2001042752A1 (en) * 1999-12-10 2001-06-14 Fujitsu Limited Temperature sensor
WO2006123085A1 (en) * 2005-05-20 2006-11-23 Transense Technologies Plc Saw torque and temperature sensor

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015064238A1 (en) * 2013-10-31 2015-05-07 京セラ株式会社 Elastic wave element, filter element and communication device
JP6050486B2 (en) * 2013-10-31 2016-12-21 京セラ株式会社 Filter element and communication device
US10153748B2 (en) 2013-10-31 2018-12-11 Kyocera Corporation Acoustic wave element, filter element, and communication device
CN106225948A (en) * 2016-07-27 2016-12-14 电子科技大学 A kind of double SAW Temperature Sensors and method for designing thereof
JP2021516906A (en) * 2018-03-16 2021-07-08 フレクエンシスＦｒｅｃ’Ｎ’Ｓｙｓ Composite substrate for SAW tags for RFID and sensor applications
JP7480936B2 (en) 2018-03-16 2024-05-10 ソイテック Composite Substrate for SAW Tags for RFID and Sensor Applications
CN114112102A (en) * 2021-11-24 2022-03-01 之江实验室 Surface acoustic wave temperature sensor with linear output characteristic and preparation method

Also Published As

Publication number Publication date
JP5527410B2 (en) 2014-06-18
JPWO2011142380A1 (en) 2013-07-22

Similar Documents

Publication Publication Date Title
WO2017188342A1 (en) Elastic wave element and communication device
JP6247377B2 (en) Elastic wave element, filter element, and communication apparatus
CN113169722A (en) Elastic wave device, branching filter, and communication device
EP1998443B1 (en) Elastic wave resonator
US8476984B2 (en) Vibration device, oscillator, and electronic apparatus
JP4569447B2 (en) Surface acoustic wave element and surface acoustic wave device
JPWO2007046236A1 (en) Lamb wave device
JP4645957B2 (en) Surface acoustic wave element and surface acoustic wave device
JP5527410B2 (en) Temperature sensor
US8692439B2 (en) Surface acoustic wave resonator, surface acoustic wave oscillator, and electronic device
US20020171513A1 (en) Surface acoustic wave device and electronic device using the same
JP2000323956A (en) Surface acoustic wave device and communication equipment
JP2010010874A (en) Surface acoustic wave filter
JP2008054163A (en) Lamb-wave type high-frequency resonator
KR100889231B1 (en) Boundary acoustic wave device
JP3255502B2 (en) Highly stable surface acoustic wave device
JP4465464B2 (en) Lamb wave type elastic wave device
WO2000067374A1 (en) Transverse double mode saw filter
WO2001035528A1 (en) Surface acoustic wave device
JP7392734B2 (en) elastic wave device
JP2007078428A (en) Surface acoustic wave sensor, and surface acoustic wave sensor system
JP2009027671A (en) Sh type bulk wave resonator
CN116781029B (en) Inclination angle determining method of resonator in filter, filter and radio frequency chip
WO2024101338A1 (en) Elastic wave resonator and communication device
JP2003298383A (en) Surface acoustic wave element

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 11780637

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2012514817

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11780637

Country of ref document: EP

Kind code of ref document: A1