JP2005094610A - Surface acoustic wave element and environmental difference detecting apparatus employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave element suitable for mass production and always stably exhibiting an excellent surface acoustic wave propagating performance, and also to provide an environmental difference detecting apparatus employing such a surface acoustic wave element. <P>SOLUTION: This surface acoustic wave element is provided with a three-dimensional substrate 12 having a surface including at least a part of a circular curved surface having a continuous curved surface through which a surface acoustic wave can propagate; an electroacoustic transducer element 14 capable of exciting a surface acoustic wave on the surface, allowing the surface acoustic wave along the surface and receiving the propagating surface acoustic wave. The three-dimensional substrate is made of LiNbO<SB>3</SB>crystal, LiTaO<SB>3</SB>crystal or a rock crystal. On the surface of the three-dimensional substrate, the electroacoustic transducer element allows the surface acoustic wave along an intersection between crystal faces of these crystals and the surface, and the intersection is the maximum external periphery line. The environmental difference detecting apparatus compares surface acoustic wave reception signals of the electroacoustic transducer elements of a plurality of propagation surface zones of the surface acoustic wave element, and detects the difference between environments of spaces with which respective signals are brought into contact. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface acoustic wave element and an environmental difference detection apparatus using the surface acoustic wave element.

  A substrate having a surface capable of exciting a surface acoustic wave (SAW) and capable of propagating the excited surface acoustic wave, and exciting the surface acoustic wave on the surface of the substrate along the surface. BACKGROUND ART A surface acoustic wave element including an electroacoustic transducer that propagates the surface acoustic wave and can receive the surface acoustic wave propagating is well known.

  The surface acoustic wave element is used as a delay line, an oscillation element, a resonance element, a frequency selection element, for example, various sensors including a chemical sensor, a biosensor, and a pressure sensor, or a remote tag.

  International Publication WO 01/45255 discloses a spherical surface acoustic wave element. The substrate of the spherical surface acoustic wave element has a spherical surface that can excite the surface acoustic wave and propagate the excited surface acoustic wave. The electroacoustic transducer of the spherical surface acoustic wave element is arranged in a band having a predetermined width that is continuous in an annular shape on the spherical surface of the base, and the surface acoustic wave excited on the surface Is propagated along the direction in which the bands are continuous and repeatedly circulated.

In the spherical surface acoustic wave element, the surface acoustic wave excited by the electroacoustic transducer is substantially attenuated within the surface acoustic wave propagation band in the annular surface acoustic wave propagation band on the surface of the substrate. The above surface can be repeatedly circulated without doing so.
International Publication WO 01/45255

  Since the surface of the surface acoustic wave element propagates the surface acoustic wave along the surface thereof, the entire surface of the substrate can be excited by the surface acoustic wave and can propagate the excited surface acoustic wave. Or by attaching a thin film formed of a surface acoustic wave excitation-propagating material to the surface thereof.

  It has been found that the substrate formed by the combination with the thin film has a high manufacturing cost and is not suitable for mass production at the present time. In the base made of only a material capable of propagating the surface acoustic wave, the elastic surface cannot propagate or circulate in the direction in which the surface acoustic wave is to propagate on the surface of the base. It has been found that there is a difference in the ability to propagate waves. Further, it is difficult to propagate or circulate the surface acoustic wave in a plurality of directions different from each other on the surface.

  The present invention has been made under the above circumstances, and an object of the present invention is a surface acoustic wave element that is suitable for mass production and can always stably exhibit good surface acoustic wave propagation performance. It is an object to provide an environmental difference detection apparatus using a surface acoustic wave element.

In order to achieve the above object, a surface acoustic wave device according to the present invention is:
A three-dimensional substrate having a surface including at least a part of an annular curved surface in which curved surfaces capable of propagating surface acoustic waves are continuous;
An electroacoustic transducer capable of exciting the surface acoustic wave on the surface and propagating the surface acoustic wave along the surface and receiving the surface acoustic wave propagating to the surface;
With
The three-dimensional substrate is LiNbO ₃ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer has a normal crystal axis defined by rotating the + Y axis, which is the crystal axis of the LiNbO ₃ crystal, by 20 ° in the + Z direction with the X axis as the rotation center. The normal axis is the crystal axis defined by rotating the + Y axis, which is the intersection of the crystal plane and the surface, and the crystal axis of the LiNbO ₃ crystal by 26 ° in the −Z direction with the X axis as the rotation center. The excited surface acoustic wave is propagated along at least one of the intersecting lines between the crystal plane and the surface, and the at least one intersecting line becomes the maximum outer peripheral line of the surface. Yes,
It is characterized by that.

In order to achieve the above object, another surface acoustic wave device according to the present invention is also:
A three-dimensional substrate having a surface including at least a part of an annular curved surface in which curved surfaces capable of propagating surface acoustic waves are continuous;
An electroacoustic transducer capable of exciting the surface acoustic wave on the surface and propagating the surface acoustic wave along the surface and receiving the surface acoustic wave propagating to the surface;
With
The three-dimensional substrate is LiTaO ₃ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer has a crystal axis defined by rotating the + Y axis, which is the crystal axis of the LiTaO ₃ crystal, by 45 ° about the X axis in the −Z direction. Along the intersection line between the crystal plane and the surface as a line, the excited surface acoustic wave is propagated, and the intersection line is the maximum outer peripheral line of the surface,
It is characterized by that.

In order to achieve the above object, yet another surface acoustic wave device according to the present invention also provides:
A three-dimensional substrate having a surface including at least a part of an annular curved surface in which curved surfaces capable of propagating surface acoustic waves are continuous;
An electroacoustic transducer capable of exciting the surface acoustic wave on the surface and propagating the surface acoustic wave along the surface and receiving the surface acoustic wave propagating to the surface;
With
The three-dimensional substrate is quartz;
The electroacoustic transducer on the surface of the three-dimensional substrate propagates the excited surface acoustic wave along an intersection line between the crystal plane and the surface with the Y axis being the crystal axis of quartz as a normal line. And the intersection line is the maximum outer peripheral line of the surface,
It is characterized by that.

  In order to achieve the above object, an environmental difference detection apparatus according to the present invention excites surface acoustic waves to a plurality of electroacoustic transducers along a plurality of intersection lines on the surface of the surface acoustic wave element according to the present invention. Propagating and receiving the surface acoustic wave propagating and outputting a reception signal, comparing reception signals output from a plurality of electroacoustic transducers, a plurality of portions where a plurality of surface acoustic waves propagate on the surface It is characterized by detecting a difference in environment in a plurality of portions of a space that touches.

  In the present invention, pseudo surface acoustic waves and, for example, corridor waves excited and propagated by an electroacoustic transducer just below the surface of the crystal material forming the three-dimensional substrate are also referred to as surface acoustic waves. . Furthermore, even an elastic wave that normally propagates along the surface of a three-dimensional substrate in contact with a different substance on the surface, such as a boundary acoustic wave, that is not usually referred to as a surface acoustic wave is used here. It is described as a wave.

  Even if any film is formed on the surface of the three-dimensional substrate where surface acoustic waves propagate, or the electroacoustic transducer is formed on the surface via any film, such a film. The presence of such a film is allowed if it does not substantially interfere with the desired propagation of surface acoustic waves.

Furthermore, in the claims, specification and drawings of the present application, the crystal axes of LiNbO ₃ , LiTaO ₃ and quartz of the three-dimensional substrate are expressed using + and − signs and X, Y and Z axes. Such an expression is a well-known expression method for the crystal axis of the piezoelectric crystal.

The surface acoustic wave element according to the present invention and the environmental difference detection device according to the present invention using the surface acoustic wave element according to the present invention have a surface for propagating the surface acoustic wave. The three-dimensional substrate is formed of LiNbO ₃ crystal, LiTaO ₃ crystal, or quartz crystal, and the electroacoustic transducer is used on the surface of each crystal along an intersection line between a specific crystal plane of each crystal and the surface. The surface acoustic wave excited on the surface is propagated, and the intersecting line is the maximum outer peripheral line of the surface, so that the surface acoustic wave device can be easily mass-produced inexpensively and is always stable. Thus, it is possible to exhibit good surface acoustic wave propagation performance.

  The “transmission / reception part” described in the present invention for exciting and receiving a surface acoustic wave on the surface of a three-dimensional substrate has two functions that are separated into a “transmission part” and a “reception part”. It can also be configured as a part. If the “transmission part” and the “reception part” are configured as mutually independent parts in this way, the design of the drive circuit and the detection circuit for these becomes easy. Since the surface acoustic wave passes through the “transmission part” and the “reception part” which are independent from each other in each round, the propagation efficiency of the surface acoustic wave is mutually different between the “transmission part” and the “reception part”. Although it is somewhat lower than the case where it is not configured as an independent part, there is no problem in practical use.

[First Embodiment]
Hereinafter, a first embodiment of a surface acoustic wave device according to the present invention will be described in detail with reference to FIGS. 1 to 4 in the accompanying drawings.

  FIG. 1 shows the appearance of the surface acoustic wave device 10 according to the first embodiment. The surface acoustic wave device 10 includes: a three-dimensional substrate 12 having a surface including a propagation surface band 12a formed by at least a part of an annular curved surface in which curved surfaces capable of propagating surface acoustic waves are continuous; An electroacoustic transducer 14 capable of exciting the surface acoustic wave to propagate the surface acoustic wave along the propagation surface zone 12a and receiving the surface acoustic wave propagating to the propagation surface zone 12a.

  Here, the propagation surface band 12a is drawn so that the dimension in the width direction W is constant in the direction in which the propagation surface band 12a continues in an annular shape for simplification of the drawing. While the surface acoustic wave propagates in the direction in which the propagation surface band 12a continues in an annular shape on the surface of 12, the surface acoustic wave may have a constant dimension in the width direction W as shown in FIG. In addition, the dimension in the width direction W may repeat diffusion and contraction.

  In any case, it is practically desired that the surface acoustic wave propagating in the propagation surface band 12a propagates at a desired distance from the electroacoustic transducer 14 or at least 80% of energy per round.

In this embodiment, the three-dimensional substrate 12 is entirely formed in a spherical shape by a trigonal LiNbO ₃ crystal. Therefore, in this embodiment, the propagation surface band 12 a is continuous in an annular shape on the spherical surface of the three-dimensional substrate 12. The propagation surface band 12a is continuous along the maximum outer peripheral line 12b of the three-dimensional substrate 12, and preferably includes the maximum outer peripheral line 12b within the range of the propagation surface band 12a.

As shown in FIG. 2A, the maximum outer peripheral line 12b on the outer surface of the three-dimensional substrate 12 has a + Y axis as one crystal axis of the LiNbO ₃ crystal and a + Z direction with the X axis as the rotation center. And the crystal plane with the crystal axis CA defined by being rotated by 20 ° as a normal line and the line of intersection with the outer surface 12 of the three-dimensional substrate 12. That is, the maximum outer peripheral line 12b along the propagation surface band 12a on the outer surface of the three-dimensional substrate 12 extends on one crystal plane of the LiNbO ₃ crystal. While surface acoustic waves propagate along the crystal plane on the outer surface of the three-dimensional substrate 12, no large diffusion of surface acoustic wave energy occurs in the direction intersecting the crystal plane. The surface acoustic wave can be propagated most efficiently on the outer surface.

Since the LiNbO ₃ crystal forming the three-dimensional substrate 12 is a trigonal system, as shown in FIG. 2B, three crystal axes + Y forming 120 ° with respect to each other in one plane. have. Therefore, the spherical outer surface of the three-dimensional substrate 12 formed entirely by LiNbO ₃ crystal is defined by rotating these three crystal axes + Y by 20 ° in the + Z direction around the X axis. When three intersecting lines between the three crystal planes having the three crystal axes CA as normals and the outer surface of the three-dimensional substrate 12 are defined as the maximum outer peripheral line 12b, the three outer peripheral lines 12b are referred to above. As described above, it is possible to define three continuous propagation surface bands 12a.

In the outer surface of the three-dimensional substrate 12 of the first embodiment, which is formed in a spherical shape by the trigonal LiNbO ₃ crystal as a whole, the propagation surface zone 12a is continuous along the outer surface. The outer peripheral line 12b can also be defined as follows.

That is, the maximum outer peripheral line 12b on the outer surface of the three-dimensional substrate 12 is centered on the X axis about the + Y axis, which is one crystal axis of the LiNbO ₃ crystal, as shown in FIG. By rotating it in the −Z direction by 26 °, it is made to coincide with the intersection line between the crystal plane having the defined crystal axis CB as the normal line and the outer surface of the three-dimensional substrate 12. This also means that in this case, the maximum outer peripheral line 12b along the propagation surface zone 12a on the outer surface of the three-dimensional substrate 12 has the three + Y axes in the LiNbO ₃ crystal in the + Z direction around the X axis. It means that the crystal axis CA rotated by 20 ° extends on one crystal plane different from the above-mentioned three crystal planes. While the surface acoustic wave propagates along the other crystal plane on the outer surface of the three-dimensional substrate 12, it intersects with the other crystal plane as in the case of the three crystal planes. Since no large diffusion of surface acoustic wave energy occurs in the direction, the surface acoustic wave can be propagated most efficiently on the outer surface of the three-dimensional substrate 12.

Since the LiNbO ₃ crystal forming the three-dimensional substrate 12 is trigonal, it has _three crystal axes + Y forming 120 ° with respect to each other as shown in FIG. doing. Therefore, on the spherical outer surface of the three-dimensional substrate 12 formed entirely by LiNbO ₃ crystal, these three crystal axes + Y are rotated by 26 ° in the −Z direction around the X axis. When three intersecting lines between the three crystal planes having the three defined crystal axes CB as normals and the outer surface 12 of the three-dimensional substrate 12 are defined as the maximum outer peripheral line 12b, the three maximum outer peripheral lines 12b As described above, it is possible to define three continuous propagation surface bands 12a.

That is, since the LiNbO ₃ crystal forming the three-dimensional substrate 12 has a total of six crystal planes, a total of six crystals are formed on the outer surface of the three-dimensional substrate 12 formed entirely by the LiNbO ₃ crystal. A maximum perimeter line 12b can be defined.

  Also, how much width the surface acoustic wave propagating on the surface of the three-dimensional substrate 12 actually has in the direction orthogonal to the propagation direction along the surface is determined by, for example, attaching water droplets to the surface. It can also be visually inferred from the fact that the surface acoustic wave does not propagate in the portion where water droplets adhere on the surface.

  In general, when interdigital electrodes are used as electroacoustic transducers to excite high-frequency surface acoustic waves, the effective width of the interdigital electrodes (that is, interdigital transducers with respect to the surface of the three-dimensional substrate). A direction in which the electrode can excite surface acoustic waves and propagate in a desired direction and can receive the surface acoustic waves propagated on the surface, in a direction perpendicular to the desired direction along the surface The effective width is the maximum outer perimeter line (indicated by reference numeral 12a in FIG. 1) where the surface acoustic wave propagates on the surface is the desired direction ( In FIG. 1, the surface acoustic wave is excited and received when the radius of curvature is greater than 1.5 times the radius of curvature of the curvature in the direction orthogonal to (indicated by reference numeral 12b). Efficiency is found to be greatly reduced.

The three-dimensional substrate 12 is supported on a support base 18 via a support arm 16 at a portion other than the propagation surface band 12 a on which the surface acoustic wave excited by the electroacoustic transducer 14 propagates on the outer surface. In order not to have any influence on the surface acoustic wave propagating through the propagation surface band 12a, nothing is brought into contact with the propagation surface band 12a except for the electroacoustic transducer 14. Therefore, in this embodiment, in order to excite the surface acoustic wave in the electroacoustic transducer 14 in the propagation surface band 12a, the surface acoustic wave propagated through the propagation surface zone 12a and received by the electroacoustic transducer 14 is electroacoustic. The electroacoustic transducer control unit 20 for receiving from the transducer 14 is connected to the electroacoustic transducer 14 by a lead wire extending from the electroacoustic transducer 14 on a region other than the propagation surface band 12a on the outer surface of the three-dimensional substrate 12. Has been. As shown in FIG. 1, for example, the electroacoustic transducer control unit 20 includes an impedance matching circuit 20a, a circulator 20, a transmitter 20c including a high frequency power supply, an amplifier 20d, a digital oscilloscope 20e, and the like. A high-frequency radio wave receiving antenna can be used instead of the transmitter 20c.

  As shown in FIG. 4A, the electroacoustic transducer 14 has an azimuth MD at which the density of the surface acoustic wave energy that is excited in the propagation surface band 12a flows to the maximum outer circumferential line 12b. It is preferable to be configured to be within 20 °. This angle is more preferably within 10 °, and further preferably within 5 °. This means that the surface acoustic wave excited on the propagation surface band 12a by the electroacoustic transducer 14 keeps 80% or more of the energy along the maximum outer peripheral line 12b on the outer surface of the three-dimensional substrate 12, for example, every turn. If it can circulate with a small attenuation rate, it may tend to diffuse from the maximum outer peripheral line 12b rather than the width immediately after being excited as it propagates, but it is preferably within the above angle range. Means.

  The term “along the maximum outer circumferential line” described in the present invention refers to the direction in which the density of the surface acoustic wave energy flow is maximum with respect to the maximum outer circumferential line when the surface acoustic wave propagates around the circulation or propagation path. The case is preferably within 20 °, more preferably within 10 °, and still more preferably within 5 °.

  In this embodiment, the electroacoustic transducer 14 is directly formed on the outer surface of the three-dimensional substrate 12 within the range of the propagation surface band 12a. In this embodiment, the electroacoustic transducer 14 is an interdigital electrode 22 such as a comb-shaped electrode, and is formed on the outer surface by various known methods such as vapor deposition, printing, sputtering, sol-gel method, and the like. It can be formed directly.

  In the case where the electroacoustic transducer 14 is formed by the interdigital electrode 22, the interdigital electrode 22 is formed with respect to the propagation surface band 12a in the interdigital electrode 22 as well shown in FIG. A line perpendicular to the outer surface of the three-dimensional substrate 12 with respect to a transmitting / receiving portion (a portion having the above-described effective width) capable of exciting a surface acoustic wave and receiving a surface acoustic wave propagating to the propagation surface zone 12a is a propagation surface zone. It is preferable to be configured so as to fall within a range of 10 ° or less with respect to the corresponding maximum outer peripheral line 12b along which 12a extends. More specifically, the transmitting / receiving portion (in the case of the interdigital electrode 22), each terminal (line element) 22 a of the pattern extends along the maximum outer peripheral line 12 b in each terminal (line element) 22 a of the interdigital electrode 22 pattern. This means that the orthogonal line OL extending along the outer surface of the propagation surface band 12a with respect to the portion overlapping each other in the direction is preferably within a range of 10 ° or less with respect to the maximum outer peripheral line 12b. .

  The reason for this is that, as described above with reference to FIG. 4A, the electroacoustic transducer 14 is maximized in the direction MD where the density of the surface acoustic wave energy flow excited in the propagation surface band 12a is maximized. This is the same as the reason why it is preferable to configure the outer peripheral line 12b to be within 20 °.

  Furthermore, the arrangement period P of the plurality of terminals 22a (see FIG. 4B) of the interdigital electrode 22 pattern in the direction along the maximum outer peripheral line 12b is 1/10 or less of the radius of curvature of the maximum outer peripheral line 12b. Preferably there is. The arrangement period P corresponds to the length of one wavelength (ie, vibration period) of the surface acoustic wave excited by the interdigital electrode 22.

  The wavelength of the surface acoustic wave (that is, the arrangement period P of the plurality of terminals 22a of the interdigital electrode 22 pattern) is the radius of curvature of the maximum outer peripheral line 12b included in the propagation surface band 12a through which the surface acoustic wave propagates (the propagation surface band 12a). Is formed by a part of a spherical surface as in this embodiment, if it is larger than 1/10 of the radius of the spherical surface), the geometric feature of the curved propagation surface band 12a is The function of suppressing the surface acoustic wave propagating through 12a from spreading is weakened. Accordingly, when a surface acoustic wave having a relatively long wavelength is to be propagated to the propagation surface band 12a on the surface of the three-dimensional substrate 12 by a desired distance, the radius of curvature of the maximum outer peripheral line 12b included in the propagation surface body 12a. Must be set in advance to satisfy the above-described relationship with the wavelength.

  Therefore, in order to propagate the surface acoustic wave efficiently in the propagation surface band 12b, it is preferable to use the arrangement period.

The diameter of the spherical three-dimensional substrate of the LiNbO ₃ crystal actually produced by the inventors of this application according to this embodiment is 25.4 mm, and the interdigital electrode used as the electroacoustic transducer is used as the spherical three-dimensional substrate. The outer surface of the crystal was formed at a position corresponding to the + X direction of the crystal as viewed from the center of the three-dimensional substrate. After forming a film by vapor deposition of 1000 angstroms of chromium or 1000 angstroms of gold on the outer surface of the three-dimensional substrate, the interdigital electrodes have terminals (line elements) as described above. The LiNbO ₃ crystal is formed by being subjected to a photolithography process so as to be orthogonal to the direction of rotation on the outer surface of the spherical shape with the + Y axis rotated about 20 ° in the + Z direction about the X axis as the rotation center. . The arrangement period P of the terminals (line elements) of the interdigital electrode pattern formed at this time is 0.532 mm, and a plurality of terminals (line elements) each having a width of 0.133 mm are arranged at intervals of 0.133 mm. Then, a desired pulse voltage is applied between terminals (line elements) adjacent to each other. And the length of the overlapping part of each adjacent terminal (line element) which an electric field produces mutually by applying a pulse voltage is 3.1 mm.

Here, the inventor of the present application has described the dimensions of an example of the interdigital electrode used as the electroacoustic transducer produced on the outer surface of the spherical three-dimensional substrate of LiNbO ₃ crystal. As long as the functions or effects required by the present invention can be achieved on the outer surface of the electrode, a currently known interdigital electrode of any material, size and shape can be used.

Then, when an impulse signal having a half-value width of 2 nanoseconds was applied to the interdigital electrode of the spherical surface acoustic wave element configured as described above at a voltage of 100 V, as a result, in the direction of circulation from the interdigital electrode. It was confirmed by a digital oscilloscope that a bursty signal having a center frequency of about 6.5 MHz was repeatedly output at least 50 times at intervals of 21.8 μsec. This is because, as described above, surface acoustic waves are generated at least 50 times at a speed of 3658 m / s on the average on the outer surface of the spherical three-dimensional substrate of LiNbO ₃ crystal having a diameter of 25.4 mm. It means that you have circulated.

The inventor of the present application also described the interdigital electrode used as an electroacoustic transducer at the same position as described above on the outer surface of the spherical three-dimensional substrate of LiNbO ₃ crystal having the same diameter as described above. Different from the above, it was formed as follows. That is, in this case, the interdigital electrode is formed on the outer surface of the three-dimensional substrate by forming a film by vapor deposition of 1000 angstroms of chromium or 1000 angstroms of gold, and then the terminals of the interdigital electrodes (line elements). ) Is perpendicular to the direction of rotation on the outer surface of the spherical shape with the + Y axis of the LiNbO ₃ crystal rotated about 26 ° in the −Z direction around the X axis as described above. It was formed by being processed. The various dimensions of the terminals (line elements) of the interdigital electrode pattern formed at this time are the same as described above.

When an impulse signal is applied to the interdigital electrode of the spherical surface acoustic wave element having the above-described configuration in the same manner as described above, about 6 in the direction of rotation from the interdigital electrode. It was confirmed by a digital oscilloscope that a burst signal having a center frequency of 5 MHz was repeatedly output at least 50 times at intervals of 22.5 μsec. This means that, as described above, surface acoustic waves are generated at least 50 times at a speed of 3540 m / s on the outer surface of the spherical three-dimensional substrate of LiNbO ₃ crystal having a diameter of 25.4 mm as described above. It means that you have circulated.

  The position of the outer surface of each of the two types of spherical surface acoustic wave elements configured as described above by the inventor of the present application is separated from the interdigital electrode in the direction in which the circuit circulates (that is, the surface acoustic wave circulation path). When a cotton swab containing water is brought into contact with the top), no output can be obtained from the interdigital electrode even if an impulse signal is applied to the interdigital electrode as described above, and the surface acoustic wave circulates. It turns out that it is obstructed. Further, the two types of spherical surface acoustic wave elements configured as described above are separated from the interdigital electrode by 5 mm or more in the direction perpendicular to the direction of the circumference (that is, the surface acoustic wave). When the impulse signal is applied to the interdigital electrode as described above, the burst signal as described above repeats from the interdigital electrode as described above. It was output and it turned out that the circumference | surroundings of a surface acoustic wave as mentioned above are not inhibited.

[First Modification]
Next, a first modification of the surface acoustic wave element according to the present invention will be described in detail with reference to FIGS.

In the surface acoustic wave device of this modification, the three-dimensional substrate 12 formed of the trigonal LiNbO ₃ crystal of the first embodiment is replaced with the same trigonal LiTaO ₃ crystal. It is formed in a spherical shape. Accordingly, the method of defining the maximum outer peripheral line 12b defined on the outer surface of the three-dimensional substrate 12 is also a three-dimensional substrate formed of the trigonal LiNbO ₃ crystal of the first embodiment described above. This is different from the case of 12. However, the configuration other than this is the same as the configuration of the surface acoustic wave element of the first embodiment described above.

In the surface acoustic wave element of the first modification, the maximum outer peripheral line 12b is shown in FIG. 5A on the outer surface of the three-dimensional substrate 12 formed entirely by a trigonal LiTaO ₃ crystal. As shown, one crystal plane of the LiTaO ₃ crystal, which is a crystal axis obtained by rotating the + Y axis, which is one crystal axis, by 45 ° in the −Z direction about the X axis as a normal, and 3 It is made to correspond to the line of intersection with the outer surface of the dimensional substrate 12. While the surface acoustic wave propagates along the one crystal plane on the outer surface of the three-dimensional substrate 12, the direction intersecting the crystal plane is the same as in the case of the crystal plane of the first embodiment. Therefore, the surface acoustic wave can be propagated most efficiently on the outer surface of the three-dimensional substrate 12.

Since the LiTaO ₃ crystal forming the three-dimensional substrate 12 is a trigonal system, as shown in FIG. 5B, it has three crystal axes + Y forming 120 ° with each other in one plane. doing. Therefore, when the three intersecting lines defined as described above for these three crystal axes + Y are defined as the maximum outer peripheral line 12b, the three propagation surface bands 12a continuous as described above along the three maximum outer peripheral lines 12b. Can be defined.

[Second Modification]
Next, a second modification example of the surface acoustic wave device according to the present invention will be described in detail with reference to FIGS.

In the surface acoustic wave device of this modification, the three-dimensional substrate 12 formed of the trigonal system LiNbO ₃ crystal of the first embodiment described above is formed into a spherical shape by using a crystal having a similar trigonal system system. Is formed. Accordingly, the method of defining the maximum outer peripheral line 12b defined on the outer surface of the three-dimensional substrate 12 is also a three-dimensional substrate formed of the trigonal LiNbO ₃ crystal of the first embodiment described above. This is different from the case of 12. However, the configuration other than this is the same as the configuration of the surface acoustic wave element of the first embodiment described above.

  In the surface acoustic wave element of the second modification, the maximum outer peripheral line 12b is shown in FIG. 6A on the outer surface of the three-dimensional substrate 12 formed entirely by trigonal crystal. As shown in the figure, it is made to coincide with the intersection line between one crystal plane having the + Y axis, which is one crystal axis CD of quartz, as a normal line and the outer surface of the three-dimensional substrate 12. While the surface acoustic wave propagates along the one crystal plane on the outer surface of the three-dimensional substrate 12, the direction intersecting the crystal plane is the same as in the case of the crystal plane of the first embodiment. Therefore, the surface acoustic wave can be propagated most efficiently on the outer surface of the three-dimensional substrate 12.

  Since the crystal forming the three-dimensional substrate 12 is a trigonal system, it has three crystal axes + Y forming 120 ° with respect to each other in one plane as shown in FIG. Yes. Therefore, when the three intersecting lines defined as described above with respect to these three crystal axes + Y are defined as the maximum outer peripheral line 12b, the three propagation surface bands 12a continuous along the three maximum outer peripheral lines 12b as described above. Can be defined.

  In the surface acoustic wave device 10 according to the first embodiment and the first and second modifications, the electroacoustic transducer 14 is excited on the outer surface of the three-dimensional substrate 12 of the surface acoustic wave device 10. The propagation surface band 12a continues in an annular shape within the range of the propagation surface band 12a in which the generated surface acoustic wave continues in an annular shape along the maximum outer peripheral line 12b defined as described above on the outer surface. The various dimensions of the three-dimensional substrate 12 are made to circulate in an annular shape with a consumption rate substantially equal to or less than 20% of the energy per cycle along the direction in which the three-dimensional substrate 12 circulates (ie, keeps 80% or more of the energy per cycle). The dimensions and various dimensions of the electroacoustic transducer 14 are set as described above.

  This means that the three-dimensional substrate 12 of the surface acoustic wave element 10 may have any arbitrary shape other than the propagation surface band 12a. For example, the three-dimensional substrate 12 can have a ring-shaped donut shape, barrel shape, rugby ball shape, or disk shape having an annular propagation surface band 12a on the outer surface.

  In the surface acoustic wave device 10 according to the first embodiment and the first and second modifications described above, there is something in the fluid (gas or fluid) filled in the space in contact with the propagation surface band 12a. If there is a change (that is, if there is any change in the external environment in contact with the propagation surface band 12a), a change occurs in the propagation speed of the surface acoustic wave propagating through the propagation surface band 12a and the propagation time required per cycle. That is, the surface acoustic wave element 10 can be used as an environmental difference detection device for detecting changes and differences in the external environment.

[Second Embodiment]
Next, a second embodiment of the surface acoustic wave device according to the present invention will be described in detail with reference to FIG.

  In this embodiment, it is prescribed as described above on the outer surface of the three-dimensional substrate 12 of the surface acoustic wave device 10 according to any of the first embodiment, the first modification, and the second modification. Other propagation surfaces in any of a plurality of propagation surface bands 12a (six in the first embodiment and three in each of the first and second modifications) As described above, the electroacoustic transducer 14 is formed in a portion that does not intersect with the belt 12a, and each electroacoustic transducer 14 is connected to the electroacoustic transducer control unit 20 described above.

  Furthermore, in this embodiment, the three-dimensional substrate 12 is supported on some pedestal (not shown) at a position excluding the plurality of propagation surface bands 12a on which the electroacoustic transducer 14 is formed on the outer surface of the three-dimensional substrate 12. The support member 32 is fixed.

  The surface acoustic wave element 30 according to the second embodiment configured as described above is different from the surface acoustic wave element 10 according to any of the first embodiment, the first and the second modifications. In comparison, it is better when used as an environmental difference detection device. The reason is as follows.

  When only one electroacoustic transducer 14 and one electroacoustic transducer control unit 20 connected to the electroacoustic transducer 14 are used as in the surface acoustic wave device 10 described above, the elastic surface is affected by the change in the external environment described above. When any physical change occurs in the wave element 10 (for example, expansion or contraction of the three-dimensional substrate 12 due to a change in the temperature of the external environment), the propagation speed of the surface acoustic wave propagating through the propagation surface band 12a or 1 A subtle change occurs in the propagation time required per period.

  Therefore, if the change of the fluid (gas or fluid) filled in the space in contact with the propagation surface zone 12a (ie, the change in the external environment in contact with the propagation surface zone 12a) is to be detected more precisely as described above. The physical change of the surface acoustic wave element 10 due to the influence of the change in the external environment described above must be taken into consideration.

  According to the surface acoustic wave device 30 according to the second embodiment with reference to FIG. 7, at least one of the plurality of propagation surface bands 12 a in which the electroacoustic transducer 14 is formed on the outer surface of the three-dimensional substrate 12. The two propagation surface bands 12a are isolated from the external environment intended to detect changes, and at least one remaining propagation surface band 12a among the plurality of propagation surface bands 12a forming the electroacoustic transducer 14 is Configure to contact the external environment.

  With such a configuration, the signal received by the electroacoustic transducer control unit 20 corresponding thereto from the electroacoustic transducer 14 on the propagation surface band 12a isolated from the external environment is received from the external environment. A physical change of the surface acoustic wave element 10 accompanying the change, and the electric power corresponding thereto from the electroacoustic transducer 14 of the remaining at least one propagation surface band 12a in contact with the external environment. The signal received by the acoustic conversion element control unit 20 indicates a change in the external environment in addition to a physical change in the surface acoustic wave element 10 accompanying a change in the external environment.

  Therefore, it is isolated from the external environment from the signal received by the electroacoustic transducer control unit 20 to which it corresponds from the electroacoustic transducer 14 of the remaining at least one propagation surface band 12a in contact with the external environment. By subtracting the signal received by the electroacoustic transducing element control unit 20 to which the electroacoustic transducing element 14 corresponding to the electroacoustic transducing element 14 on the propagating surface band 12a corresponds, only a change in the external environment is detected. Is possible.

[Modification]
FIG. 8 shows a modification of the surface acoustic wave element 30 according to the second embodiment described with reference to FIG.

  In this modification, a common excitation electroacoustic transducer element 14 ′ common to the plurality of propagation surface bands 12 a is formed in the intersecting region of the plurality of propagation surface bands 12 a on the outer surface of the three-dimensional substrate 12. The common excitation electroacoustic transducer 14 'is connected to the common excitation electroacoustic transducer control unit 20', and the common excitation electroacoustic transducer control unit 20 'propagates through the common excitation electroacoustic transducer 14'. Control is performed so that a surface acoustic wave having the same frequency is simultaneously excited and propagated through the surface band 12a.

  In addition, reception electroacoustic transducers 14 '' are formed at positions that do not overlap each other in each of the plurality of propagation surface bands 12a. Each of the plurality of receiving electroacoustic transducers 14 '' is connected to the receiving electroacoustic transducer element control unit 20 '', and each receiving electroacoustic transducer element control unit 20 '' is connected to each receiving electroacoustic transducer element control unit 20 ''. The receiving electroacoustic transducer control unit 20 ″ is connected to a signal difference detecting means 24 for detecting a difference in received signals.

  Usually, the plurality of receiving electroacoustic transducers 14 ″ simultaneously receive surface acoustic waves from the plurality of propagation surface bands 12 a. However, for example, when a foreign substance such as a liquid comes into contact with any one of the propagation surface bands 12a due to a change in the environment of a portion of the external space adjacent to any one of the propagation surface bands 12a, any one of the foreign objects contacted. There is a difference between the propagation speed of surface acoustic waves in one propagation surface band 12a and the propagation speeds of surface acoustic waves in the remaining plurality of propagation surface bands 12a that are not in contact with foreign matter. Due to this difference, the signal difference detecting means 24 connected to the plurality of receiving electroacoustic transducers 14 '' via the plurality of receiving electroacoustic transducer elements 20 '' has an environment in the external space portion. You can know the degree of change.

  In this modification, one common excitation electroacoustic transducer 14 'is formed for a plurality of propagation surface bands 12a, and a corresponding plurality of receiving electroacoustic transducers 14' 'are formed. Therefore, one common excitation electroacoustic element control unit 20 ′ for one common excitation electroacoustic transducer 14 ′, and a plurality of receiving electricity for a plurality of receiving electroacoustic transducers 14 ″. An acoustic conversion element control unit 20 ″ is provided.

  The circuit designs of the common excitation electroacoustic element control unit 20 ′ and the plurality of receiving electroacoustic transducing element control units 20 ″ of such a modification are the same as those in the second embodiment shown in FIG. Compared to each circuit design of the plurality of electroacoustic transducer control units 20 for transmission / reception control provided corresponding to the plurality of electroacoustic transducers 14 for transmission / reception with respect to the plurality of propagation surface bands 12a of the form Easy to.

[Third Embodiment]
Next, a third embodiment of a surface acoustic wave device according to the present invention will be described in detail with reference to FIG.

  In the surface acoustic wave element 40 according to the third embodiment, the three-dimensional substrate 12 has a recess or a hollow portion, and the surface 12c of the recess or the hollow portion can propagate the surface acoustic wave. The curved surface includes a propagation surface band 12a that is continuous in an annular shape. FIG. 9 shows a three-dimensional substrate 12 having a through hole which is a kind of hollow portion.

The three-dimensional substrate 12 is entirely formed of LiNbO ₃ crystal, LiTaO ₃ crystal, or quartz crystal, as in the three-dimensional substrate 12 of the first embodiment and the first or second modification described above. . At least a plurality of crystal planes peculiar to the type of crystal forming the three-dimensional substrate 12 on the outer surface of the three-dimensional substrate 12 of the first embodiment and the first or second modification described above. The surface acoustic wave device 40 according to the third embodiment is similar to the surface acoustic wave element 40 according to the third embodiment in the same manner that the maximum outer peripheral line 12b serving as a reference for extending the propagation surface band 12a along the intersection line between one and the outer surface is defined. At least one serving as a reference for causing the propagation surface zone 12a to follow the intersection line between the inner surface and at least one of a plurality of crystal planes specific to the type of crystal forming the three-dimensional substrate 12 on the inner surface of the three-dimensional substrate 12 Two maximum perimeter lines 12b are defined. A propagation surface band 12a is defined so as to continuously extend along the maximum outer peripheral line 12b on the inner surface. The method of defining the propagation surface zone 12a on the inner surface of the three-dimensional substrate 12 of this embodiment is the same as that of the first embodiment described above and the outer surface of the three-dimensional substrate 12 of the first or second modification. This is the same as the method of defining the propagation surface band 12a. Therefore, the maximum outer peripheral line 12b is preferably included in the range of the propagation surface band 12a on the inner surface.

  Then, the electroacoustic acoustic wave is also propagated to the propagation surface band 12a on the inner surface of the three-dimensional substrate 12 of this embodiment along the maximum outer peripheral line 12b within the propagation surface band 12a without being greatly attenuated. A conversion element 14 is formed, and the electroacoustic conversion element control unit 20 is connected to the electroacoustic conversion element 14.

  Also in this embodiment, as long as the propagation surface band 12a is defined by the predetermined method described above, the shape of the portion other than the propagation surface band 12a is arbitrary.

  The surface acoustic wave element 40 according to this embodiment is excited by the electroacoustic transducer 14 on the propagation surface band 12a and propagates in the propagation surface band 12a without significant attenuation while maintaining energy of, for example, 80% or more per round. The surface acoustic wave changes in response to various changes in the fluid (gas or fluid) passing through the internal space of the through hole, which is the environment in contact with the propagation surface band 12a on the inner surface of the three-dimensional substrate 12. By receiving as an electrical signal by the electroacoustic transducer control unit 20 via the acoustic transducer 14, it is possible to detect the change in the environment, that is, the difference.

  Further, in this embodiment, similarly to the surface acoustic wave element 30 of the second embodiment described above with reference to FIG. 7, the type of crystal forming the three-dimensional substrate 12 on the inner surface is used. Each of the plurality of propagation surface bands 12a along the plurality of maximum outer peripheral lines 12b matched with the plurality of lines of intersection between the specific plurality of crystal planes and the inner surface has intersections with the other propagation surface bands 12a. Except for this, the electroacoustic transducer 14 to which the above-described electroacoustic transducer control unit 20 is connected can be formed. In this case as well, like the surface acoustic wave element 30 of the second embodiment described above with reference to FIG. 7, it can be used as an environmental difference detection device that can detect environmental differences more precisely. I can do it.

  Furthermore, also in this embodiment, the three-dimensional substrate 12 is formed on the outer surface in the same manner as the surface acoustic wave element 30 of the modification of the second embodiment described above with reference to FIG. A plurality of propagation surface belts 12a are formed at intersections of a plurality of propagation surface belts 12a along a plurality of maximum outer peripheral lines 12b that coincide with a plurality of intersection lines between a plurality of crystal planes peculiar to the type of crystal and the outer surface. It is also possible to form a common electroacoustic transducer element 14 ′ for common excitation and a receiving electroacoustic transducer element 14 ″ outside the intersecting region in each of the plurality of propagation surface bands 12a. In this case as well, like the surface acoustic wave element 30 of the modification of the second embodiment described above with reference to FIG. 8, it is used as an environmental difference detection device that can detect environmental differences more precisely. I can do it.

[Fourth Embodiment]
Next, a fourth embodiment of a surface acoustic wave device according to the present invention will be described in detail with reference to FIGS.

The surface acoustic wave device 50 according to the fourth embodiment is entirely composed of LiNbO ₃ crystal and LiTaO, similarly to the three-dimensional substrate 12 of the first embodiment and the first or second modification. A spherical three-dimensional substrate 12 made of _three crystals or quartz is provided. On the outer surface of the three-dimensional substrate 12, at least one of a plurality of intersecting lines between a plurality of crystal planes of the material of the three-dimensional substrate 12 and the outer surface is a maximum outer peripheral line 12b, and an annular shape is formed along the maximum outer peripheral line 12b. A continuous propagation surface zone 12a is defined. The propagation surface band 12a on the outer surface of the three-dimensional substrate 12 of the surface acoustic wave element 50 of this embodiment is also the three-dimensional substrate 12 of the first embodiment and the first or second modification. Similar to the propagation surface zone 12a on the outer surface of the substrate, it preferably includes a maximum outer peripheral line 12b within the range of the propagation surface zone 12a.

  The surface acoustic wave element 50 of this embodiment is different from the surface acoustic wave elements 10 of the first embodiment and the first and second modifications in that the propagation on the outer surface of the three-dimensional substrate 12 is performed. The electroacoustic transducer 14 for exciting the surface acoustic wave on the surface band 12a and propagating the excited surface acoustic wave along the maximum outer peripheral line 12b within the range of the propagation surface band 12a propagates on the outer surface of the three-dimensional substrate 12. That is, it is not formed directly on the surface band 12a.

  In this embodiment, the propagation surface zone facing region in which the pedestal 52 that supports a portion other than the propagation surface zone 12a on the outer surface of the three-dimensional substrate 12 faces the propagation surface zone 12a with a predetermined gap S therebetween. The electroacoustic transducer 14 is formed in the propagation surface zone facing region 52 a of the pedestal 52. The dimensions and arrangement of the electroacoustic transducer 14 with respect to the propagation surface band 12a are the same as those in the surface acoustic wave device 10 of the first embodiment and the first and second modifications. It is the same as the case where it is formed.

  When the electroacoustic transducer 14 is a comb-like electrode 22 such as a comb-shaped electrode, the predetermined gap S is an array period P of a plurality of line elements (terminals) of the pattern of the comb-like electrode 22 ((B in FIG. 4). It is preferable that it is 1/4 or less of (see)). When the predetermined gap S is not less than ¼ of the arrangement period P (see FIG. 4B), the electroacoustic transducer 14 has a desired elasticity on the propagation surface band 12a on the outer surface of the three-dimensional substrate 12. It becomes difficult to always reliably excite surface waves.

  The surface acoustic wave element 50 according to the fourth embodiment can be used in the same manner as the three-dimensional substrate 12 of the first embodiment and the first or second modification. Moreover, when the electroacoustic transducer 14 faces the propagation surface band 12a on the outer surface of the three-dimensional substrate 12 via a predetermined gap S, the propagation surface band 12a on the outer surface of the three-dimensional substrate 12 Compared with the case where the electroacoustic transducer 14 is directly formed, the electroacoustic transducer 14 formed directly on the propagation surface band 12a is excited by the electroacoustic transducer 14 to the propagation surface zone 12a and the propagation surface zone 12a. It is possible to eliminate the influence that may slightly affect the surface acoustic wave propagating through the inside, and it is possible to detect the change of the surface acoustic wave propagating through the propagating surface band 12a more precisely.

  Further, also in the surface acoustic wave element 50 according to the fourth embodiment, as in the modification of the second embodiment of the present invention described above with reference to FIG. The propagation surface band facing region 52a of the pedestal 52 is made to face the intersecting region of the plurality of propagation surface belts 12a along the plurality of maximum outer peripheral lines 12b, and the three-dimensional substrate A common excitation electroacoustic transducer 14 ′ facing each other through a predetermined gap S can be formed in the intersecting region of the plurality of propagation surface bands 12 a on the outer surface of 12. Further, in each of the plurality of propagation surface bands 12a, an additional pedestal propagation surface band facing region similar to the pedestal 52 having the propagation surface band facing region 52a outside the intersecting region is faced, and the propagation of this additional pedestal A receiving electroacoustic transducer 14 '' facing each other through the predetermined gap S outside the intersecting area in each of the plurality of propagation surface bands 12a on the outer surface of the three-dimensional substrate 12 is formed in the surface band facing area. I can do it. In this case as well, like the surface acoustic wave element 30 of the modification of the second embodiment described above with reference to FIG. 8, it is used as an environmental difference detection device that can detect environmental differences more precisely. I can do it.

[Fifth Embodiment]
Next, a fifth embodiment of a surface acoustic wave device according to the present invention will be described in detail with reference to FIG.

  The surface acoustic wave element 60 according to the fifth embodiment includes a three-dimensional substrate 12 ′ having a hemispherical shape, and a curved surface capable of propagating surface acoustic waves is formed on the outer surface of the three-dimensional substrate 12 ′. It includes a propagation surface band 12′a formed by a part of at least a continuous annular curved surface.

The hemispherical three-dimensional substrate 12 ′ is entirely made of LiNbO ₃ crystal, LiTaO ₃ crystal, or quartz crystal, like the three-dimensional substrate 12 of the first embodiment and the first or second modification. Is formed. At least a plurality of crystal planes peculiar to the type of crystal forming the three-dimensional substrate 12 on the outer surface of the three-dimensional substrate 12 of the first embodiment and the first or second modification described above. The surface acoustic wave according to the fifth embodiment is the same as the maximum outer peripheral line 12b serving as a reference for continuously extending the propagation surface body 12a along the line of intersection between one and the outer surface. The at least one of a plurality of crystal planes peculiar to the type of crystal forming the three-dimensional substrate 12 'on the hemispherical outer surface of the three-dimensional substrate 12' of the element 60 is made to coincide with the intersection line of the outer surface. , At least one maximum outer peripheral line 12'b is defined as a reference for continuously extending the propagation surface body 12'a. Preferably, the maximum outer peripheral line 12'b is included in the range of the propagation surface band 12'a.

  The method of defining the maximum outer peripheral line 12′b, which serves as a reference for the propagation surface band 12′a along the outer surface of the three-dimensional substrate 12 ′ of this embodiment, is the same as that in the first embodiment and the first embodiment. Alternatively, the method is the same as the method of defining the maximum outer peripheral line 12b on the outer surface of the three-dimensional substrate 12 of the second modification.

  Further, the surface acoustic wave per round is also applied to the propagation surface band 12′a on the outer surface of the three-dimensional substrate 12 ′ of this embodiment along the maximum outer peripheral line 12′b within the range of the propagation surface band 12′a. The electroacoustic transducer 14 is directly formed to propagate and maintain at least 80% or more energy, and the electroacoustic transducer control unit 20 is connected to the electroacoustic transducer 14.

  In this embodiment, the propagation of the surface acoustic wave that is excited by the electroacoustic transducer 14 within the range of the propagation surface zone 12′a and propagates along the maximum outer peripheral line 12′b within the range of the propagation surface zone 12′a. A surface acoustic wave reflector 62 is formed at a position away from the electroacoustic transducer 14 in the direction. The surface acoustic wave reflector 62 transmits the surface acoustic wave propagated from the electroacoustic transducer 14 through the propagation surface zone 12'a toward the surface acoustic wave reflector 62 through the propagation surface zone 12'a through the same path. Reflected toward the acoustic transducer 14.

  Also in this embodiment, the shape of the portion other than the propagation surface band 12'a is arbitrary as long as the propagation surface band 12'a is defined by the predetermined method described above.

  Also in this embodiment, the three-dimensional substrate 12 'is supported by a pedestal (not shown) except for the propagation surface band 12'a.

  The surface acoustic wave device 60 according to this embodiment is excited by the electroacoustic transducer 14 to the propagation surface band 12'a formed of at least a part of an annular curved surface, and does not significantly attenuate the inside of the propagation surface band 12'a. The propagating surface acoustic wave changes in response to various changes in the fluid (gas or fluid) contained in the external space, which is the environment in contact with the propagating surface band 12'a on the outer surface of the three-dimensional substrate 12. Is received as an electrical signal by the electroacoustic transducer control unit 20 via the electroacoustic transducer 14, so that the environmental change, that is, the difference can be detected.

  Further, also in this embodiment, similar to the surface acoustic wave element 30 of the second embodiment described above with reference to FIG. 7, the kind of crystal forming the three-dimensional substrate 12 ′ on the outer surface Each of the plurality of propagation surface bands 12′a along the plurality of maximum outer peripheral lines 12′b defined by the plurality of intersecting lines between the plurality of crystal planes peculiar to the outer surface and the other outer surface, The electroacoustic transducer 14 to which the above-described electroacoustic transducer control unit 20 is connected can be formed except for the intersection with 'a. In this case, the surface acoustic wave reflector 62 is installed at a position facing the electroacoustic transducer 14 in each of the plurality of propagation surface bands 12'a except for an intersection with the other propagation surface band 12'a.

  Further, in the same manner as the surface acoustic wave element 30 of the modification of the second embodiment described above with reference to FIG. 8, in the intersection region of the plurality of propagation surface bands 12′a on the outer surface of the three-dimensional substrate 12 ′. A common excitation electroacoustic transducer 14 ′ is formed, and a receiving electroacoustic transducer 14 ″ is formed outside the intersecting region in each of the plurality of propagation surface bands 12′a instead of the surface acoustic wave reflector 62. May be.

  Furthermore, in this embodiment, as in the surface acoustic wave device 40 of the third embodiment described above with reference to FIG. 9, for example, a hemispherical recess or cavity formed in the three-dimensional substrate 12 A propagation surface band 12a formed by at least a part of an annular curved surface with a center line 12b on the inner surface is defined, and such propagation surface bands 12a are separated from each other along the center line 12a and face each other. The acoustic conversion element 14 and the surface acoustic wave reflector 62 can be modified to be installed.

  Furthermore, in this embodiment as well, as in the surface acoustic wave element 50 of the fourth embodiment described above with reference to FIGS. 10 and 11, electric power is directly applied to the propagation surface band 12a of the three-dimensional substrate 12 ′. Instead of forming the acoustic transducer 14, the electroacoustic transducer 14 can be formed on a pedestal (not shown) so as to face the propagation surface band 12 a via a predetermined gap S, or the three-dimensional substrate 12. A common excitation electroacoustic transducer 14 'is formed on the above-mentioned pedestal (not shown) so as to oppose the intersecting regions of the plurality of propagation surface bands 12'a on the outer surface of the sheet with a predetermined gap S and a plurality of propagation surfaces. The receiving electroacoustic transducer 14 '' can be formed on the above-mentioned pedestal (not shown) so as to face each other through the predetermined gap S other than the intersecting region in each of the bands 12'a.

  Furthermore, another electroacoustic transducer 14 to which the above-described electroacoustic transducer control unit 20 is connected can be used instead of the surface acoustic wave reflector 62.

1 is a schematic view of a surface acoustic wave device according to a first embodiment of the present invention. (A) is a propagation that propagates a surface acoustic wave to the outer surface of the three-dimensional substrate when the entire three-dimensional substrate of the surface acoustic wave device according to the first embodiment of the present invention is formed of LiNbO ₃ crystal. There how to define along the maximum peripheral line as a reference surface zone into one of three crystal faces of the LiNbO ₃ crystal perspective view schematically showing; and, as (B) is, (a) FIG. 3 is a schematic view of a three-dimensional substrate as viewed from a + Z direction to a −Z direction in order to show three maximum outer peripheral lines serving as references for three propagation surface bands set on the outer surface of the three-dimensional substrate. (A) is a propagation that propagates a surface acoustic wave to the outer surface of the three-dimensional substrate when the entire three-dimensional substrate of the surface acoustic wave device according to the first embodiment of the present invention is formed of LiNbO ₃ crystal. how to define along the maximum peripheral line as a reference surface zone to one another three crystal faces of the LiNbO ₃ crystal be a perspective view showing schematically; and, (B) is, as the (a) FIG. 6 is a schematic view of the three-dimensional substrate viewed from the −Z direction to the −Z direction in order to show three maximum outer peripheral lines that are the reference for another three propagation surface bands defined on the outer surface of the three-dimensional substrate. . (A) is a schematic view of a preferable state in which the electroacoustic transducer is arranged with respect to the corresponding maximum outer peripheral line in the propagation surface zone of the three-dimensional substrate of the surface acoustic wave device according to the first embodiment of the present invention. And (B) is an interdigital electrode with respect to the corresponding maximum peripheral line in the propagation surface zone of the three-dimensional substrate of the surface acoustic wave device according to the first embodiment of the present invention. It is a figure which shows schematically the further more preferable state by which the electroacoustic conversion element by is arrange | positioned. (A) shows the surface acoustic wave on the outer surface of the three-dimensional substrate when the entire three-dimensional substrate of the surface acoustic wave element is formed of LiTaO ₃ crystal in accordance with the first modification of the first embodiment of the present invention. FIG. 2 is a perspective view schematically showing a state in which a maximum outer peripheral line serving as a reference of a propagation surface zone for propagating a crystal is defined along one of three crystal faces of a LiTaO ₃ crystal; and (B) is (A) FIG. 6 is a schematic view of the three-dimensional substrate viewed from the + Z direction to the −Z direction in order to show the three maximum outer peripheral lines that are the reference for the three propagation surface bands defined on the outer surface of the three-dimensional substrate. . (A) is a case where a surface acoustic wave is propagated to the outer surface of a three-dimensional substrate when the entire three-dimensional substrate of the surface acoustic wave element is formed of quartz according to the second modification of the first embodiment of the present invention. FIG. 6 is a perspective view schematically showing a state in which a maximum outer peripheral line serving as a reference of a propagation surface band to be formed is defined along one of three crystal planes of quartz; and (B) is as shown in (A). FIG. 3 is a schematic view of a three-dimensional substrate as viewed from a −Z direction to a −Z direction in order to show three maximum outer peripheral lines serving as a reference for three propagation surface bands defined on the outer surface of the three-dimensional substrate. It is a perspective view which shows roughly the surface acoustic wave element according to 2nd Embodiment of this invention. FIG. 8 is a perspective view schematically showing a surface acoustic wave device according to a modification of the second embodiment in FIG. 7. It is a perspective view which shows roughly the surface acoustic wave element according to 3rd Embodiment of this invention. It is a perspective view which shows roughly the surface acoustic wave element according to 4th Embodiment of this invention. 10 schematically shows a state in which the electroacoustic transducer is formed on the pedestal of the three-dimensional substrate so as to face the propagation surface band on the outer surface of the three-dimensional substrate of the surface acoustic wave device of FIG. 10 with a predetermined gap. FIG. It is a perspective view which shows roughly the surface acoustic wave element according to 5th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Surface acoustic wave element, 12 ... Three-dimensional base | substrate, 12a ... Propagation surface zone, 12b ... Maximum outer periphery line, 12c ... Inner surface, 14 ... Electroacoustic transducer, 14 '... Electroacoustic transducer for common excitation, 14' '... Receiving electroacoustic transducer, 22 ... Interdigital electrode, 22a ... Line element (terminal), CA, CB, CC, CD ... Crystal axis direction, P ... Arrangement period.

Claims (21)

A three-dimensional substrate having a surface including at least a part of an annular curved surface in which curved surfaces capable of propagating surface acoustic waves are continuous;
An electroacoustic transducer capable of receiving the surface acoustic wave propagating along the surface while exciting the surface acoustic wave on the surface and propagating the surface acoustic wave along the surface;
With
The three-dimensional substrate is LiNbO ₃ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer has a normal crystal axis defined by rotating the + Y axis, which is the crystal axis of the LiNbO ₃ crystal, by 20 ° in the + Z direction with the X axis as the rotation center. The normal axis is the crystal axis defined by rotating the + Y axis, which is the intersection of the crystal plane and the surface, and the crystal axis of the LiNbO ₃ crystal by 26 ° in the −Z direction with the X axis as the rotation center. The excited surface acoustic wave is propagated along at least one of the intersecting lines between the crystal plane and the surface, and the at least one intersecting line becomes the maximum outer peripheral line of the surface. Yes,
A surface acoustic wave device. On the surface of the three-dimensional substrate, the electroacoustic transducer has a normal crystal axis defined by rotating the + Y axis, which is the crystal axis of the LiNbO ₃ crystal, by 20 ° in the + Z direction with the X axis as the rotation center. The normal axis is the crystal axis defined by rotating the + Y axis, which is the intersection of the crystal plane and the surface, and the crystal axis of the LiNbO ₃ crystal by 26 ° in the −Z direction with the X axis as the rotation center. Along the line of intersection between the crystal plane and the surface, the excited surface acoustic wave is propagating, each of the lines of intersection being the maximum perimeter of the surface,
The surface acoustic wave device according to claim 1.   3. The surface acoustic wave device according to claim 1, wherein the surface of the three-dimensional substrate has at least a part of a spherical surface. The surface has a curved surface in which the surface acoustic wave can propagate and is continuous in an annular shape,
The electroacoustic transducer is configured to excite the surface acoustic wave on the surface and propagate and circulate the surface acoustic wave along the intersection line.
The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is provided.   The surface acoustic wave device according to claim 4, wherein the surface of the three-dimensional substrate is a spherical surface. A three-dimensional substrate having a surface including at least a part of an annular curved surface in which curved surfaces capable of propagating surface acoustic waves are continuous;
An electroacoustic transducer capable of receiving the surface acoustic wave propagating along the surface while exciting the surface acoustic wave on the surface and propagating the surface acoustic wave along the surface;
With
The three-dimensional substrate is LiTaO ₃ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer has a crystal axis defined by rotating the + Y axis, which is the crystal axis of the LiTaO ₃ crystal, by 45 ° about the X axis in the −Z direction. Along the intersection line between the crystal plane and the surface as a line, the excited surface acoustic wave is propagated, and the intersection line is the maximum outer peripheral line of the surface,
A surface acoustic wave device.   The surface acoustic wave device according to claim 6, wherein the surface of the three-dimensional substrate has at least a part of a spherical surface. The surface has a curved surface in which the surface acoustic wave can propagate and is continuous in an annular shape,
The electroacoustic transducer is configured to excite the surface acoustic wave on the surface and propagate and circulate the surface acoustic wave along the intersection line.
The surface acoustic wave device according to claim 7.   9. The surface acoustic wave device according to claim 8, wherein the surface of the three-dimensional substrate is a spherical surface. A three-dimensional substrate having a surface including at least a part of an annular curved surface in which curved surfaces capable of propagating surface acoustic waves are continuous;
An electroacoustic transducer capable of receiving the surface acoustic wave propagating along the surface while exciting the surface acoustic wave on the surface and propagating the surface acoustic wave along the surface;
With
The three-dimensional substrate is quartz;
The electroacoustic transducer on the surface of the three-dimensional substrate propagates the excited surface acoustic wave along an intersection line between the crystal plane and the surface with the Y axis being the crystal axis of quartz as a normal line. And the intersection line is the maximum outer peripheral line of the surface,
A surface acoustic wave device.   The surface acoustic wave device according to claim 10, wherein the surface of the three-dimensional substrate has at least a part of a spherical surface. The surface has a curved surface in which the surface acoustic wave can propagate and is continuous in an annular shape,
The electroacoustic transducer is configured to excite the surface acoustic wave on the surface and propagate and circulate the surface acoustic wave along the intersection line.
The surface acoustic wave device according to claim 10.   The surface acoustic wave device according to claim 12, wherein the surface of the three-dimensional substrate is a spherical surface. In the direction intersecting with the extending direction of the intersecting line along the surface, the electroacoustic transducer excites a surface acoustic wave on the surface, and the energy of the surface acoustic wave along the intersecting line is 80% per round. Propagating while maintaining the above, the dimension capable of receiving the surface acoustic wave is 1 / 1.5 or less of the curvature radius of the curved surface extending in the direction perpendicular to the intersecting line on the surface,
The surface acoustic wave device according to any one of claims 1 to 13, wherein the surface acoustic wave device is provided.   The electroacoustic transducer has a direction in which the energy flow density of the surface acoustic wave emitted from the electroacoustic transducer along the intersecting line is maximum within 20 ° with respect to the corresponding intersecting line. The surface acoustic wave device according to claim 14, wherein the surface acoustic wave device is disposed on a surface.   The surface acoustic wave device according to any one of claims 1 to 15, wherein the electroacoustic transducer is formed in the propagation surface zone.   The electroacoustic transducer includes an interdigital electrode, and the interdigital electrode excites a surface acoustic wave to the surface at a plurality of terminals of the interdigital electrode and transmits the surface acoustic wave propagating to the surface. The surface acoustic wave device according to any one of claims 1 to 16, wherein a receivable transmission / reception part includes a part of a corresponding intersection line.   18. The surface acoustic wave device according to claim 17, wherein an arrangement period of the plurality of terminals of the interdigital electrode in a direction along the intersecting line is 1/10 or less of a radius of curvature of the intersecting line. .   The surface acoustic wave device according to claim 1, wherein the surface of the three-dimensional substrate is an outer surface of the three-dimensional substrate.   The said three-dimensional base | substrate has a recess or a hollow part, The said surface is an inner surface of the recess or hollow part of the said three-dimensional base | substrate, The any one of Claim 1 thru | or 18 characterized by the above-mentioned. The surface acoustic wave device according to Item.   21. The surface acoustic wave according to claim 1, wherein the surface acoustic wave is excited and propagated to a plurality of electroacoustic transducers along a plurality of intersection lines on the surface of the surface acoustic wave element. The received signals are output, the received signals output from the plurality of electroacoustic transducers are compared, and the difference in the environment of the plurality of portions of the space where the plurality of portions where the plurality of surface acoustic waves propagate on the surface is in contact is determined. An environmental difference detection device characterized by detecting.

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