JP2005094609A - 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; and 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, wherein the three-dimensional substrate is made of Li<SB>2</SB>B<SB>4</SB>O<SB>7</SB>crystal or Bi<SB>12</SB>SiO<SB>20</SB>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 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 a Bi ₁₂ SiO ₂₀ crystal;
The electroacoustic transducer on the surface of the three-dimensional substrate propagates the excited surface acoustic wave along a line of intersection between the crystal plane (111) of the Bi ₁₂ SiO ₂₀ crystal and the surface. The line is the maximum perimeter line of the surface,
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 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 a Li ₂ B ₄ O ₇ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer is excited along an intersection line between a crystal plane normal to a direction perpendicular to the C crystal axis of the Li ₂ B ₄ O ₇ crystal and the surface. The 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 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 a Li ₂ B ₄ O ₇ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer is a crystal plane whose normal is a direction inclined between 30 ° and 40 ° in an arbitrary direction from the C crystal axis of the Li ₂ B ₄ O ₇ crystal. And along the line of intersection with the surface, the excited surface acoustic wave is propagated, the line of intersection 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.

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 Bi ₁₂ SiO ₂₀ crystal or Li ₂ B ₄ O ₇ crystal, and the surface of each crystal is electrically connected along the line of intersection between the specific crystal plane of each crystal and the surface. Surface acoustic waves excited on the surface by the acoustic transducer are propagated, and the intersecting line is the maximum outer peripheral line of the surface, so that the surface acoustic wave elements can be easily mass-produced at low cost. In addition, it is possible to exhibit stable surface acoustic wave propagation performance constantly and stably.

  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 3 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 entire three-dimensional substrate 12 is formed in a spherical shape from Li ₂ B ₄ O ₇ crystals. 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. 2, the maximum outer peripheral line 12b on the outer surface of the three-dimensional substrate 12 has an arbitrary direction from the C crystal axis of the Li ₂ B ₄ O ₇ crystal (note that the arbitrary direction and Is an arbitrary angular direction in the entire circumference of 360 ° centered on the C crystal axis) and the crystal plane with the direction CA inclined between 30 ° and 40 ° as a normal and the outside of the three-dimensional substrate 12 It matches the line of intersection with the surface. 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 Li ₂ B ₄ O ₇ crystal. While the surface acoustic wave propagates along the crystal plane on the outer surface of the three-dimensional substrate 12, the energy of the surface acoustic wave generated in the crystal plane when the surface acoustic wave propagates so as to intersect the crystal plane. Therefore, the surface acoustic wave can be propagated most efficiently on the outer surface of the three-dimensional substrate 12.

In the outer surface of the three-dimensional substrate 12 of the first embodiment, which is formed entirely in a spherical shape by Li ₂ B ₄ O ₇ crystal, the maximum outer periphery in which the propagation surface band 12a continues along the outer surface. The 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 a crystal plane whose normal is the direction CB perpendicular to the C crystal axis of the Li ₂ B ₄ O ₇ crystal as shown in FIG. And the line of intersection with the outer surface of the three-dimensional substrate 12. Even in this case, the maximum outer peripheral line 12b along which the propagation surface zone 12a extends along the outer surface of the three-dimensional substrate 12 is in any direction from the C crystal axis of the Li ₂ B ₄ O ₇ crystal (also here) The above arbitrary direction is an arbitrary angular direction in the entire circumference of 360 ° centering on the C crystal axis), and a crystal plane whose normal is a direction CA inclined between 30 ° and 40 ° Means extending on the crystal plane specified separately. While the surface acoustic wave propagates along the crystal plane separately defined on the outer surface of the three-dimensional substrate 12, it is separately defined as in the case of the crystal plane described above with reference to FIG. The surface acoustic wave can be propagated most efficiently on the outer surface of the three-dimensional substrate 12 because no large diffusion of the surface acoustic wave energy occurs in the direction intersecting the crystal plane.

  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 has an azimuth MD at which the density of the surface acoustic wave energy excited in the propagation surface band 12a is maximized. This is the same reason that it is preferable to configure the 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.

Further, when the three-dimensional substrate 12 is formed of the Li ₂ B ₄ O ₇ crystal as described above, a surface acoustic wave is excited on the outer surface of the three-dimensional substrate 12 to propagate the surface acoustic wave along the outer surface. In addition, the transmission / reception part of the electroacoustic transducer 14 capable of receiving the surface acoustic wave propagating on the outer surface is arranged so as to include a part of the intersecting line (maximum outer peripheral line 12b) on the outer surface of the three-dimensional substrate 12. I know that it is preferable. With such an arrangement, the transmission / reception part of the electroacoustic transducer 14 can excite and receive the surface acoustic wave more efficiently.

In addition to such an arrangement, when the three-dimensional substrate 12 is formed of Li ₂ B ₄ O ₇ crystal as described above and the maximum outer peripheral line 12b is defined as shown in FIG. In order to further increase the efficiency of the transmitting / receiving unit of the electroacoustic transducer 14, the transmitting / receiving unit of the electroacoustic transducer 14 is further illustrated in FIG. Further, it has been found that it is further preferable to arrange in a zone AA indicating between 75 ° and 105 ° in an arbitrary direction from the C axis.

  If the spherical three-dimensional substrate 12 is assumed to be the earth, the C-axis corresponds to the earth's axis on the earth, and the maximum outer peripheral line 12b defined as shown in FIG. 3 corresponds to the meridian on the earth. A band AA defined as shown in FIG. 2 corresponds to a band-like portion extending continuously in an annular shape along the equator between 15 ° north latitude and 15 ° south latitude on the earth.

  In FIG. 2, the band AA is only shown on the outer surface of the three-dimensional substrate 12 in order to prevent the drawing from being complicated, but is actually a portion that cannot be seen on the outer surface of the three-dimensional substrate 12. In addition, it has a continuous annular shape.

[First Modification]
Next, a modification of the surface acoustic wave device according to the present invention will be described in detail.

In the surface acoustic wave element according to this modification, the three-dimensional substrate 12 formed of the Li ₂ B ₄ O ₇ crystal of the first embodiment is formed into a spherical shape using Bi ₁₂ SiO ₂₀ crystal. . Accordingly, the method for defining the maximum outer peripheral line 12b on the outer surface of the three-dimensional substrate 12 is also the case of the three-dimensional substrate 12 formed of the Li ₂ B ₄ O ₇ crystal of the first embodiment described above. Is different. However, the configuration other than this is the same as the configuration of the surface acoustic wave element of the first embodiment described above.

The surface acoustic wave device of this _{modification,} Bi 12 _{SiO 20} the maximum peripheral line 12b in the three-dimensional substrate 12 the outer surface of the whole is formed by _{crystallization,} Bi 12 crystal plane of _{SiO 20} crystal (111) and three-dimensional It is made to correspond to the intersection line with the outer surface of the base 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.

[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.

  The surface acoustic wave device 30 of this embodiment is defined 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 and the modification described above. As described above, the electroacoustic transducers 14 are formed in portions of the plurality of propagating surface strips 12a that do not intersect with the other propagating surface strips 12a. The acoustic conversion element control unit 20 is connected.

  In FIG. 5, the propagation surface band 12 a is shown only on the outer surface of the three-dimensional substrate 12 in order to prevent the drawing from being complicated, but in reality, it is not visible on the outer surface of the three-dimensional substrate 12. The portion also has an annular shape continuously along the maximum outer peripheral line 12b.

Here, in the case where the three-dimensional substrate 12 is formed of Li ₂ B ₄ O ₇ crystal as described above, a surface acoustic wave is excited on the outer surface of the three-dimensional substrate 12 to generate a surface acoustic wave along the outer surface. The transmission / reception part of the electroacoustic transducer 14 capable of propagating and receiving the surface acoustic wave propagating on the outer surface is arranged so as to include a part of the intersection line (maximum outer peripheral line 12b) on the outer surface of the three-dimensional substrate 12. It is preferable that With such an arrangement, the transmission / reception part of the electroacoustic transducer 14 can excite and receive the surface acoustic wave more efficiently.

In addition to such an arrangement, when the three-dimensional substrate 12 is formed of Li ₂ B ₄ O ₇ crystal as described above and the maximum outer peripheral line 12b is defined as shown in FIG. In order to further increase the efficiency of the transmitting / receiving unit of the electroacoustic transducer 14, the transmitting / receiving unit of the electroacoustic transducer 14 is further illustrated in FIG. 2 on the outer surface of the three-dimensional substrate 12. Further, it is more preferable that they are arranged in a zone AA showing between 75 ° and 105 ° in an arbitrary direction from the C axis.

  Furthermore, in this embodiment, the three-dimensional substrate 12 is placed on any pedestal (not shown) at a position excluding the plurality of propagation surface bands 12a and the band AA where the electroacoustic transducer 14 is formed on the outer surface of the three-dimensional substrate 12. A support member 32 for supporting is fixed.

  The surface acoustic wave element 30 according to the second embodiment configured as described above is more environmentally sensitive than the surface acoustic wave element 10 according to any of the first embodiment and the modification. It is better when used as a 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. 5, 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.

[Third Embodiment]
Next, a third embodiment of the 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. 6 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 Li ₂ B ₄ O ₇ crystal or Bi ₁₂ SiO ₂₀ crystal, as with the three-dimensional substrate 12 of the first embodiment and its modification. In addition, at least one of 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 its modification, and the outer surface, The inner surface of the three-dimensional substrate 12 of the surface acoustic wave device 40 according to the third embodiment is defined in the same manner as the maximum outer peripheral line 12b serving as a reference for extending the propagation surface band 12a along the intersection line is defined. In addition, at least one maximum outer peripheral line 12b serving as a reference for causing the propagation surface band 12a to follow an intersection line between at least one of a plurality of crystal planes peculiar to the type of crystal forming the three-dimensional substrate 12 and the inner surface is provided. It is prescribed. 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 band 12a on the inner surface of the three-dimensional substrate 12 of this embodiment is the same as the definition of the propagation surface band 12a on the outer surface of the three-dimensional substrate 12 of the first embodiment and its modifications. Is the same as 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. 5, the type of crystal in which the three-dimensional substrate 12 is formed 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. 5, it can be used as an environmental difference detection device that can detect environmental differences more precisely. I can do it.

Furthermore, in this embodiment as well, as in the surface acoustic wave device 30 of the second embodiment described above with reference to FIG. 5, the three-dimensional substrate 12 has the Li ₂ B ₄ O ₇ crystal as described above. The electroacoustic transducer 14 is capable of exciting a surface acoustic wave on the inner surface of the three-dimensional substrate 12 to propagate the surface acoustic wave along the outer surface and receiving the surface acoustic wave propagating on the inner surface. It is preferable that the transmission / reception part includes a part of the intersecting line (maximum outer peripheral line 12b) on the inner surface of the three-dimensional substrate 12. With such an arrangement, the transmission / reception part of the electroacoustic transducer 14 can excite and receive the surface acoustic wave more efficiently.

In addition to such an arrangement, when the three-dimensional substrate 12 is formed of Li ₂ B ₄ O ₇ crystal as described above and the maximum outer peripheral line 12b is defined as shown in FIG. In order to further increase the efficiency of the transmitting / receiving unit of the electroacoustic transducer 14, the transmitting / receiving unit of the electroacoustic transducer 14 is further illustrated in FIG. 2 on the inner surface of the three-dimensional substrate 12. Further, it is more preferable that they are arranged in a zone AA showing between 75 ° and 105 ° in an arbitrary direction from the C axis.

[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 element 50 according to the fourth embodiment is entirely composed of Li ₂ B ₄ O ₇ crystal or Bi ₁₂ SiO, as with the three-dimensional substrate 12 of the first embodiment and its modification. A spherical three-dimensional substrate 12 formed of ₂₀ crystals 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 propagated on the outer surface of the three-dimensional substrate 12 of the first embodiment and its modification. Similar to the surface band 12a, the maximum outer peripheral line 12b is preferably included within the range of the propagation surface band 12a.

  The surface acoustic wave element 50 according to this embodiment is different from the surface acoustic wave element 10 according to the first embodiment or the modified example in that the surface acoustic wave is propagated to the propagation surface band 12 a on the outer surface of the three-dimensional substrate 12. An electroacoustic transducer 14 for exciting the wave and propagating the excited surface acoustic wave along the maximum outer peripheral line 12b within the range of the propagation surface band 12a is directly formed on the propagation surface band 12a on the outer surface of the three-dimensional substrate 12. It is not done.

  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 the case where the electroacoustic transducer 14 is directly formed on the propagation surface band 12a in the surface acoustic wave device 10 of the first embodiment or the modification. It is the same.

  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 its 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, in this embodiment, similarly to the surface acoustic wave element 30 of the second embodiment described above with reference to FIG. 5, the type of crystal in which the three-dimensional substrate 12 is formed on the outer 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, the propagation surface zone facing region 52a of the pedestal 52 is made to face, and the propagation surface zone facing region 52a faces the crossing region of the plurality of propagation surface zones 12a on the outer surface of the three-dimensional substrate 12 through a predetermined gap S. The electroacoustic transducer 14 facing each other 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. 5, it can be used as an environmental difference detection device that can detect environmental differences more precisely. I can do it.

Furthermore, in this embodiment as well, as in the surface acoustic wave device 30 of the second embodiment described above with reference to FIG. 5, the three-dimensional substrate 12 has the Li ₂ B ₄ O ₇ crystal as described above. The electroacoustic transducer 14 is capable of exciting a surface acoustic wave on the outer surface of the three-dimensional substrate 12 to propagate the surface acoustic wave along the outer surface and receiving the surface acoustic wave propagating on the inner surface. Is preferably arranged so as to include a part of the intersecting line (maximum outer peripheral line 12 b) on the outer surface of the three-dimensional substrate 12. With such an arrangement, the transmission / reception part of the electroacoustic transducer 14 can excite and receive the surface acoustic wave more efficiently.

In addition to such an arrangement, when the three-dimensional substrate 12 is formed of Li ₂ B ₄ O ₇ crystal as described above and the maximum outer peripheral line 12b is defined as shown in FIG. In order to further increase the efficiency of the transmitting / receiving unit of the electroacoustic transducer 14, the transmitting / receiving unit of the electroacoustic transducer 14 is further illustrated in FIG. 2 on the outer surface of the three-dimensional substrate 12. Further, it is more preferable that they are arranged in a zone AA showing between 75 ° and 105 ° in an arbitrary direction from the C axis.

[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 formed entirely of Li ₂ B ₄ O ₇ crystal or Bi ₁₂ SiO ₂₀ crystal, like the three-dimensional substrate 12 of the first embodiment and its modification. Yes. In addition, at least one of 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 its modification, and the outer surface, The three-dimensional substrate of the surface acoustic wave device 60 according to the fifth embodiment is defined in the same manner as the maximum outer peripheral line 12b serving as a reference for continuously extending the propagation surface body 12a along the intersection line The propagation surface body 12 ′ is matched with an intersection line of at least one of a plurality of crystal planes peculiar to the type of crystal forming the three-dimensional substrate 12 ′ on the outer surface of the 12 ′ hemisphere and the outer surface. At least one maximum outer peripheral line 12′b is defined as a reference for continuously running 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 that 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 of the first embodiment described above and its modifications. This is the same as the method of defining the maximum outer peripheral line 12b on the outer surface of the three-dimensional substrate 12.

  Further, the surface wave 12′a on the outer surface of the three-dimensional substrate 12 ′ of this embodiment also has a surface acoustic wave of at least 80% along the maximum outer peripheral line 12′b within the range of the surface band 12′a. The electroacoustic transducer 14 is directly formed so as to keep the above energy and propagate, 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, in this embodiment as well, similar to the surface acoustic wave device 30 of the second embodiment described above with reference to FIG. 5, the kind of crystal in which the three-dimensional substrate 12 ′ is formed 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.

Furthermore, in this embodiment as well, as in the surface acoustic wave element 30 of the second embodiment described above with reference to FIG. 5, the three-dimensional substrate 12 ′ is formed of Li ₂ B ₄ O ₇ as described above. In the case of being formed of crystals, electroacoustic conversion capable of exciting a surface acoustic wave with respect to the outer surface of the three-dimensional substrate 12 'and propagating the surface acoustic wave along the outer surface and receiving the surface acoustic wave propagating through the inner surface. It is preferable that the transmitting / receiving part of the element 14 is arranged so as to include a part of the intersecting line (maximum outer peripheral line 12′b) on the outer surface of the three-dimensional substrate 12 ′. With such an arrangement, the transmission / reception part of the electroacoustic transducer 14 can excite and receive the surface acoustic wave more efficiently.

In addition to such an arrangement, the three-dimensional substrate 12 ′ is formed of the Li ₂ B ₄ O ₇ crystal as described above, and the maximum outer peripheral line 12′b is defined as shown in FIG. 2, in order to further increase the efficiency of the transmitting / receiving unit of the electroacoustic transducer 14, the transmitting / receiving unit of the electroacoustic transducer 14 is further illustrated in FIG. 2 on the outer surface of the three-dimensional substrate 12 ′. It is further preferable that it is arranged in a zone AA showing between 75 ° and 105 ° in an arbitrary direction from the C-axis.

  Furthermore, in this embodiment, as in the surface acoustic wave element 40 of the third embodiment described above with reference to FIG. 6, for example, a hemispherical recess or cavity formed in the three-dimensional substrate 12 ′. A propagation surface band 12'a formed by at least a part of an annular curved surface with a maximum outer peripheral line 12'b on the inner surface of the inner surface of the inner surface of the substrate, and along the maximum outer peripheral line 12a. The electroacoustic transducer 14 and the surface acoustic wave reflector 62 that are separated from each other and face each other may be modified to be installed.

  Furthermore, in this embodiment, similarly to the surface acoustic wave element 50 of the fourth embodiment described above with reference to FIGS. 7 and 8, the propagation surface band 12′a of the three-dimensional substrate 12 ′ is formed. Instead of directly forming the electroacoustic transducer 14, the electroacoustic transducer 14 can be formed on a pedestal (not shown) so as to face the propagation surface band 12 ′ a through a predetermined gap S.

  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. Propagation surface for propagating surface acoustic waves to the outer surface of a 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 Li ₂ B ₄ O ₇ crystal FIG. 3 is a perspective view schematically showing a state in which a maximum outer peripheral line serving as a reference of a band is defined along one of a group of crystal planes of a Li ₂ B ₄ O ₇ crystal and a preferable band for arranging an electroacoustic transducer. . Propagation surface for propagating surface acoustic waves to the outer surface of a 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 Li ₂ B ₄ O ₇ crystal how to define along the maximum peripheral line as a reference band to one of the crystal face of another group of Li ₂ B ₄ O ₇ crystal is a perspective view schematically showing. (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. It is a perspective view which shows roughly the surface acoustic wave element according to 2nd Embodiment of this invention. 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. 7 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. 7 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, 12 '... Three-dimensional base | substrate, 12a, 12'a ... Propagation surface zone, 12b, 12'b ... Maximum outer periphery line, 12c ... Inner surface, 14 ... Electroacoustic transducer 14' ... electroacoustic transducers, 22 ... interdigital electrodes, 22a ... line elements (terminals), 30, 40, 50, 60 ... surface acoustic wave elements, AA ... band, C ... C-axis, CA, CB ... direction, P ... Array period.

Claims (24)

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 a Bi ₁₂ SiO ₂₀ crystal;
The electroacoustic transducer on the surface of the three-dimensional substrate propagates the excited surface acoustic wave along a line of intersection between the crystal plane (111) of the Bi ₁₂ SiO ₂₀ crystal and the surface. The line is the maximum perimeter line of the surface,
A surface acoustic wave device.   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.   The surface acoustic wave device according to claim 3, wherein the surface of the three-dimensional substrate is a spherical surface.   The transmitting / receiving part of the electroacoustic transducer that can excite the surface acoustic wave to the surface of the three-dimensional substrate and propagate the surface acoustic wave along the surface and receive the surface acoustic wave propagating through the surface, 5. The surface acoustic wave device according to claim 2, wherein the surface acoustic wave element is disposed so as to include a part of the intersection line on the surface of the three-dimensional substrate. 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 a Li ₂ B ₄ O ₇ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer is excited along an intersection line between a crystal plane normal to a direction perpendicular to the C crystal axis of the Li ₂ B ₄ O ₇ crystal and the surface. The 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.   The transmitting / receiving part of the electroacoustic transducer that can excite the surface acoustic wave to the surface of the three-dimensional substrate and propagate the surface acoustic wave along the surface and receive the surface acoustic wave propagating through the surface, 10. The surface acoustic wave device according to claim 7, wherein the surface acoustic wave element is disposed so as to include a part of the intersection line on the surface of the three-dimensional substrate. 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 a Li ₂ B ₄ O ₇ crystal;
On the surface of the three-dimensional substrate, the electroacoustic transducer is a crystal plane whose normal is a direction inclined between 30 ° and 40 ° in an arbitrary direction from the C crystal axis of the Li ₂ B ₄ O ₇ crystal. And along the line of intersection with the surface, the excited surface acoustic wave is propagated, the line of intersection is the maximum outer peripheral line of the surface,
A surface acoustic wave device.   The surface acoustic wave device according to claim 11, 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 11.   The surface acoustic wave device according to claim 13, wherein the surface of the three-dimensional substrate is a spherical surface.   The transmitting / receiving part of the electroacoustic transducer that can excite the surface acoustic wave to the surface of the three-dimensional substrate and propagate the surface acoustic wave along the surface and receive the surface acoustic wave propagating through the surface, 10. The surface acoustic wave device according to claim 7, wherein the surface acoustic wave element is disposed so as to include a part of the intersection line on the surface of the three-dimensional substrate.   The transmitter / receiver of the electroacoustic transducer is further arranged at least partially in a region between 75 ° and 105 ° in an arbitrary direction from the C axis on the surface of the three-dimensional substrate. The surface acoustic wave device according to claim 15. 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 16, wherein the surface acoustic wave device is characterized in that:   The electroacoustic transducer has a direction in which the density of the surface acoustic wave energy flowing from the electroacoustic transducer along the intersecting line reaches a maximum within 20 ° including 20 ° with respect to the corresponding intersecting line. The surface acoustic wave device according to claim 17, wherein the surface acoustic wave device is disposed on the surface so as to become.   The surface acoustic wave device according to any one of claims 1 to 18, wherein the electroacoustic transducer is formed in the propagation surface band.   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 line perpendicular to the surface with respect to a receivable transmission / reception part is configured to fall within a range of 10 ° or less with respect to a corresponding intersection line. The surface acoustic wave device according to Item.   21. The surface acoustic wave device according to claim 20, 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 any one of claims 1 to 21, 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 21 characterized by the above-mentioned. The surface acoustic wave device according to Item.   24. 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 intersecting 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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