JP4852240B2 - Spherical surface acoustic wave element and rotation angle measuring device - Google Patents

Description

The present invention relates to a spherical surface acoustic wave device and the rotation angle measurement equipment.

  In recent years, surface acoustic wave devices such as high-frequency signal processing electronic devices using surface acoustic waves, high-frequency filters, or surface acoustic wave propagation path measurement sensors are being put into practical use.

  The surface acoustic wave device can be built in a very small size as a signal processing device because the propagation speed of the surface acoustic wave is very slow compared to the electromagnetic wave. In addition, once electromagnetic waves are converted into surface acoustic waves, they can be used in various signal processing devices such as frequency filters, harmonic oscillators using nonlinear phenomena, or light modulation elements based on the interaction between light and elastic waves. It is possible to apply.

  These applications are possible because surface acoustic waves have the property of being easily changed by being affected by changes in electrical signals, electromagnetic waves, pressure, and chemical environment. In each element, usually, an electric signal is converted into a surface acoustic wave, and after the surface acoustic wave has some interaction with the surrounding environment, it is converted into an electric signal again. That is, in each element, the surface acoustic wave is more susceptible to the surrounding environment than the electric signal, and therefore the surface acoustic wave is used only in a part of the electric circuit.

  On the other hand, unlike surface acoustic waves, electrical signals are not affected by the outside along the propagation path (wiring), are stably transmitted with little attenuation, and transmit information to the next signal processing process. It is possible. Such stability of electric signals promotes the use of various electric circuits and leads to the development of today's electronics industry.

  Also, what is called an optical circuit using an optical signal that is stable like an electric signal has been proposed. An optical circuit is very stable without being affected by electromagnetic waves, and enables a large amount of information to be transmitted through an optical fiber. Optical substrates using optical circuits are also being put to practical use. Optical substrates are made of ferroelectrics, switches are made using liquid crystals, and frequency filters (wavelength filters) are made using interference fringe patterns. Thus, it has also been proposed to construct a logical operation circuit.

  However, since the surface acoustic wave is easily affected by the surrounding environment as described above, the surface acoustic wave is used only in a part of each element, unlike these electric signals and optical signals. In fact, circuits using surface acoustic waves for information transmission have hardly been put to practical use. One of the causes is that it is difficult to efficiently propagate surface acoustic waves over long distances.

  In view of this, a surface acoustic wave waveguide has been considered to stably transmit and receive surface acoustic waves.

  However, when a surface acoustic wave carrying information such as a high-frequency signal is propagated on a waveguide, the influence of the medium structure is far greater than that of an electromagnetic wave. As a result, the surface acoustic wave is converted into various elastic wave modes and is difficult to control.

  Although surface acoustic waves are diffused by diffraction, it is very difficult to make a waveguide on a flat substrate for suppressing the diffraction phenomenon.

  In the surface acoustic wave device, it is difficult to realize many functions realized by semiconductor components such as a switch, an amplifier, and an adder circuit as well as a waveguide. For this reason, the function corresponding to the semiconductor component is usually realized by an electronic circuit once converted into an electric signal, rather than partially using a surface acoustic wave.

  In addition, it is difficult for surface acoustic wave devices to have the function of allowing surface acoustic waves to interact with each other and holding (storing) information on vibration patterns of elastic waves for a certain period of time. And devices used for information transmission, and what can be called surface acoustic wave circuits have not been realized.

  On the other hand, some surface acoustic wave devices utilize spherical surface acoustic wave elements. A spherical surface acoustic wave element is an interdigital electrode formed individually or individually on the surface of a piezoelectric crystal sphere, and excites and detects surface acoustic waves.

  In this surface acoustic wave device using a spherical surface acoustic wave element, a surface acoustic wave circulates on the surface of a sphere, so that a very long distance is propagated and a slight change in the propagation speed for each lap is detected. can do.

  In addition, on the surface of the spherical surface acoustic wave element, the surface acoustic wave including phase information can be stored for a very long time compared to the time required for one round of the element surface (circulation time). Furthermore, by setting the beam width when exciting the surface acoustic wave within the range determined by the wavelength and the diameter of the sphere, it is possible to propagate a very narrow path without almost diffusing the energy of the surface acoustic wave. . The beam width can be designed by the overlapping width of the electrodes when the surface acoustic wave excitation means is an interdigital electrode.

 Then, the rotation time of the surface acoustic wave and the state where the circulation path is an integral multiple of the wavelength of the surface acoustic wave are detected from the output information and used as an index. A sensor that detects a change in the sensitive film can also be configured.

For such a sensor, for example, a spherical surface acoustic wave element having a sensitive film that changes the propagation speed of the surface acoustic wave by a specific gas is used, and by comparing the outputs of the surface acoustic waves of a plurality of propagation paths, the temperature etc. There is a method of calibrating the variation factor and trying to accurately measure the concentration of a specific gas.
In this method, it is necessary to form a plurality of interdigital electrodes on the same three-dimensional substrate and apply a high frequency signal for excitation to excite surface acoustic waves in a plurality of circulation paths. In addition, it is necessary to separately digitize outputs from a plurality of detection means and compare them.

  In the above-described sensor or the like, a switch or the like that exchanges energy of a plurality of surface acoustic waves propagating through a plurality of propagation paths to activate an interaction is desired.

On the other hand, the surface acoustic wave element is not limited to the above-described sensor, but has been proposed to be used for a gyro for detecting and measuring changes in rotation and orientation (for example, see Patent Document 1). Here, as shown in FIG. 20, the planar gyro 40 is formed on an acoustic wave base 41 with interdigital electrodes 42 a and 42 b for standing wave excitation, reflectors 43 a and 43 b, a surface acoustic wave perturbation body 44, and an elastic surface. Wave detecting interdigital electrodes 45a and 45b are provided. First, the interdigital electrodes 42a and 42b for standing wave excitation excite surface acoustic waves on the surface of the elastic wave substrate 41. The excited surface acoustic wave propagates in the left-right direction on the surface of the substrate, is reflected by the reflectors 43a and 43b at both ends, and forms a standing wave between the reflectors 43a and 43b. In the antinode portion of the standing wave, vertical vibration having a vibration component in the vertical direction of the substrate is generated by the surface acoustic wave perturbation body 44. At this time, when the planar gyroscope 40 rotates, the vertical vibration of the antinode of the standing wave changes to an elliptical vibration by Coriolis force according to the rotational motion of the elastic wave base 41. As a result, a traveling elastic wave such as a Rayleigh wave is generated and propagates from the surface acoustic wave perturbation body 44 in a direction orthogonal to the path of the standing wave. This elastic wave is detected by the interdigital electrode 45a or 45b for detecting the surface acoustic wave. If such a gyro is realized, there is no mechanical structure, the operation is stable, and high sensitivity by high frequency becomes easy.
JP-A-8-334330

  As described above, in the surface acoustic wave device, it is difficult to propagate the surface acoustic wave stably over a long distance. In addition, even if an area where a plurality of propagation paths are overlapped to form a circuit, it is possible to branch a surface acoustic wave, exchange energy, or influence surface acoustic waves in other propagation paths. This was not possible due to the linearity of surface acoustic waves. In other words, even when the propagation paths intersect spatially, the surface acoustic waves do not interact with each other and cannot influence each other.

  Accordingly, a surface acoustic wave circuit such as a switch for operating the surface acoustic wave propagating in the other propagation path cannot be constituted by the surface acoustic wave propagating in one propagation path.

  Furthermore, it has the function of propagating a surface acoustic wave with a narrow beam width to a predetermined path and adding a perturbation from the outside to excite and propagate a new surface acoustic wave or branch it to another propagation path. It was difficult to realize the signal path.

  On the other hand, in order to excite the standing wave of the surface acoustic wave, the conventional planar gyroscope requires two standing wave excitation interdigital electrodes 42a and 42b, respectively, and reflectors 43a and 43b. For this reason, the reflectors 43a and 43b inevitably increase the size of the device.

  A planar gyro diffracts energy because the surface acoustic wave confined in a specific propagation path is diffracted by the surface acoustic wave perturbant in the propagation process that reciprocates along the propagation path even when the planar substrate does not rotate. Leakage occurs in both directions due to the phenomenon.

  Therefore, a planar gyro is a highly sensitive gyro even if it is intended to create a propagation path in which surface acoustic waves propagate with a high energy density, for example, a gyro that leaks energy in a direction away from the propagation path due to perturbation due to rotation. It is difficult.

  The present invention has been made in consideration of the above circumstances, and enables the stable propagation of surface acoustic waves in the form of a beam, enables the interaction of surface acoustic waves in a region where a plurality of propagation paths overlap, and enables the generation of surface acoustic waves. An object of the present invention is to provide a spherical surface acoustic wave device that can contribute to the realization of a circuit.

Still another object of the present invention is to provide while preventing energy leakage such as planar gyro, a spherical surface acoustic wave device and the rotation angle measurement equipment can achieve a compact gyro which utilizes the surface acoustic wave With the goal.

The invention corresponding to claim 1 has a three-dimensional substrate having a propagation path composed of at least a part of a spherical surface capable of propagating surface acoustic waves, and a surface of the propagation path according to an input drive signal. A surface acoustic wave for exciting a first surface acoustic wave of a beam having a wavelength of the surface acoustic wave less than 1/30 of the diameter of the sphere surface and a width of less than 1/5 of the diameter of the sphere surface. Depending on the rotational movement of the excitation means and the three-dimensional substrate, the first surface acoustic wave is perturbed in a direction different from the propagation direction by the propagation path, and is less than 1/30 of the diameter of the spherical surface A surface acoustic wave perturbation means for exciting and propagating a second surface acoustic wave of a beam having a wavelength of the surface acoustic wave and a width equal to or less than one-fifth of the diameter of the sphere surface, and the surface acoustic wave perturbation The second surface acoustic wave that has been excited and propagated in different directions by means is detected. And a surface acoustic wave detecting means for outputting a detection signal, wherein the propagation path has an annular surface formed of a continuous curved surface, and at least a part of the annular surface includes the surface acoustic wave. The surface acoustic wave excitation means is disposed in at least two circulation paths that intersect each other , and the surface acoustic wave perturbation means is configured to rotate the three-dimensional substrate in three axial directions. Accordingly, the first surface acoustic wave propagating through the circulation path is individually perturbed, and the second surface acoustic wave is separately excited and propagated in a direction different from the circulation path. At least one is formed in the path and at least three in total, and the surface acoustic wave detection means detects the second surface acoustic wave that is excited and propagated by the plurality of surface acoustic wave perturbation means. Three Respectively disposed on the propagation path, a spherical surface acoustic wave device for propagating surface acoustic waves from one channel to another channel.

According to a second aspect of the present invention, in the spherical surface acoustic wave element corresponding to the first aspect , the three-dimensional substrate has a plurality of the propagation paths intersecting each other and a circulation path formed in each propagation path. The surface acoustic wave detecting means propagates the surface acoustic wave from one propagation path to another propagation path, which is disposed on a circulation path different from the circulation path around which the excited second surface acoustic wave circulates. This is a spherical surface acoustic wave element.

According to a third aspect of the present invention, in the spherical surface acoustic wave element corresponding to the first or second aspect , the surface acoustic wave excitation means is configured such that the first surface acoustic wave is standing along the circular path. The surface acoustic wave perturbation means excites a wave and is periodically formed at a position where the amplitude of the standing wave is maximized in a partial region of the circulation path, and the position where the amplitude is minimized. It is a spherical surface acoustic wave element that propagates a surface acoustic wave from one propagation path to another propagation path, which is composed of structures having different densities and / or heights.

According to a fourth aspect of the present invention, in the spherical surface acoustic wave element corresponding to the first or second aspect , the surface acoustic wave excitation means is a first circuit that circulates the surfaces of the three-dimensional substrate in opposite directions. The surface acoustic wave perturbation means has the function of generating a standing wave in at least a part of the circulation path by exciting a surface acoustic wave and causing the first surface acoustic wave to circulate to interfere with each other. The standing surface wave is perturbed according to the rotational motion of the three-dimensional substrate, and the second surface acoustic wave is excited and propagated in a direction different from the circumferential direction. This is a spherical surface acoustic wave element that propagates a surface acoustic wave from one propagation path to another propagation path, in which structures having different densities and / or heights are provided at the wave antinodes.

According to a fifth aspect of the present invention, in the spherical surface acoustic wave element according to any one of the first to fourth aspects, the surface acoustic wave excitation means is in contact with or close to the surface of the three-dimensional substrate. Propagation consisting of an interdigital electrode for applying an electric field of the drive signal and a piezoelectric material for converting the electric field applied from the interdigital electrode into a surface acoustic wave by a piezoelectric effect. It is a spherical surface acoustic wave element that propagates a surface acoustic wave from a path to another propagation path.

The invention corresponding to claim 6 is the spherical surface acoustic wave element corresponding to any one of claims 1 to 5 , wherein the three-dimensional substrate is a piezoelectric crystal, and is propagated from one propagation path to another. It is a spherical surface acoustic wave element that propagates surface acoustic waves through a road.

The invention corresponding to claim 7 is the spherical surface acoustic wave element corresponding to any one of claims 1 to 6 , wherein the surface acoustic wave detecting means converts the surface acoustic wave into an electric field by a piezoelectric effect. This is a spherical surface acoustic wave element that propagates a surface acoustic wave from one propagation path to another propagation path, which is composed of a piezoelectric material for the purpose and an interdigital electrode for outputting a detection signal corresponding to the electric field.

An invention corresponding to claim 8 is a rotation angle measuring device comprising the spherical surface acoustic wave element according to any one of claims 1 to 7, wherein a high-frequency signal is used as the drive signal to form the elastic surface. A drive signal input means for inputting to the wave excitation means; and a detection signal output from the surface acoustic wave detection means by the perturbation being added to the surface acoustic wave in accordance with the rotational motion of the three-dimensional substrate after the drive signal is inputted. And a rotation angle measuring device for measuring the rotation angle of the three-dimensional substrate.

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

  Similarly, in the present invention, a surface acoustic wave element having a spherical boundary (spherical boundary acoustic wave element) is a spherical surface acoustic wave as long as it is an element based on a phenomenon in which surface acoustic waves propagate on a spherical surface or boundary. It will be called an element. For example, a spherical surface acoustic wave device is not limited to a device in which a three-dimensional substrate has a spherical shape, and if the propagation path has a spherical surface, the surface may have only a hemispherical surface, or a part of the spherical shape may be a planar shape. The element processed into the other shape is also included.

  In this specification, the term “perturbation” refers to an action that changes the propagation state of a surface acoustic wave by an active action from the outside (eg, rotational movement of a three-dimensional substrate). It is distinguished from the “diffraction” of the surface acoustic wave by the structure of the diffractive body or the perturbing body that does not include a typical action. However, there are various mechanical or electromagnetic phenomena that affect the actual wave propagation or excite a new wave using a part of the energy. "Perturbation", "diffraction"). For this reason, in the individual implementation, these various phenomena are included in the two expressions, and therefore it is not necessary to investigate which of the two expressions corresponds.

<Action>
The invention corresponding to claim 1 excites surface acoustic wave perturbation means for exciting a surface acoustic wave on the surface of the three-dimensional substrate and propagating the surface acoustic wave in a propagation direction different from the propagation direction of the excited surface acoustic wave. The configuration provided in the path enables stable surface acoustic wave propagation and enables interaction between surface acoustic waves in a region where multiple propagation paths overlap, contributing to the realization of a surface acoustic wave circuit. A spherical surface acoustic wave device can be provided.

In the invention corresponding to claim 1 , in addition to the above-described action, the propagation path is a revolving path in which the surface acoustic wave can circulate. Therefore, a substantially very long distance can be circulated by the surface acoustic wave. It is possible to provide a spherical surface acoustic wave element suitable for a surface acoustic wave circuit for detecting or measuring the above.

In the invention corresponding to claim 1 , the surface acoustic wave is excited on the surface of the three-dimensional substrate, and the surface acoustic wave excited by the perturbation according to the rotational motion of the three-dimensional substrate is detected. Unlike a type of surface acoustic wave element, since it is not necessary to provide a reflector, a small gyro using surface acoustic waves can be realized. Moreover, since it is realized by a spherical surface acoustic wave element, it is possible to prevent leakage of energy as in a planar gyro.

In the invention corresponding to claim 1 , in addition to the above-described action, the three-dimensional substrate has an annular surface made of a continuous curved surface, and therefore, a circulation path of the surface acoustic wave can be formed. Since it is possible to circulate the surface acoustic wave to be excited, it is not necessary to provide a reflector capable of realizing a compact gyro.
Further, the invention corresponding to claim 1 generates a plurality of surface acoustic waves, and individually changes and detects the propagation direction of the surface acoustic waves according to the rotational motion of the three-dimensional substrate in the three axial directions. Thus, it is possible to provide an element capable of detecting a general rotational orientation and capable of measuring three axes.

In the invention corresponding to claim 2 , in addition to the action corresponding to claim 1 , the surface acoustic wave diffracted wave detecting means excited by the perturbation is arranged on different circulation paths, so that the surface acoustic wave is efficiently detected. be able to. As a result, the amount of rotation can be obtained efficiently.

In addition to the actions corresponding to claims 1 and 2 , the invention corresponding to claims 3 and 4 increases the strength by making the surface acoustic wave a standing wave, and the density and / or height as the surface acoustic wave perturbation means. By providing a structure having different surface acoustic wave propagation directions, the propagation direction of the surface acoustic wave can be changed. As a result, the rotation amount can be obtained.

In the invention corresponding to claim 5 , in addition to the actions corresponding to claims 1 to 4 , since the surface acoustic wave excitation means is composed of the interdigital electrode and the piezoelectric material, the surface acoustic wave can be efficiently excited. it can. As a result, the amount of rotation can be obtained efficiently.

In the invention corresponding to claim 6 , in addition to the actions corresponding to claims 1 to 5 , since the piezoelectric crystal is used for the three-dimensional substrate, the propagation path is formed without using a process such as film formation of the piezoelectric thin film. Can be formed. Thereby, the manufacturing process of an element can be made easy.

In the invention corresponding to claim 7 , in addition to the actions corresponding to claims 1 to 6 , the surface acoustic wave detecting means is composed of the interdigital electrode and the piezoelectric material, so that it propagates in a direction different from the propagation direction by the propagation path. It is possible to efficiently detect the generated surface acoustic wave. As a result, the amount of rotation can be obtained efficiently.

In addition to the actions corresponding to claims 1 to 7 , the invention corresponding to claim 8 detects a surface acoustic wave whose propagation direction is changed according to the rotational motion of the three-dimensional substrate of the spherical surface acoustic wave element, and spherical The rotation angle of the surface acoustic wave element can be obtained.

  As described above, according to the present invention, a stable surface acoustic wave can be propagated, and interaction between surface acoustic waves can be realized in a region where a plurality of propagation paths overlap, thereby realizing a surface acoustic wave circuit. It is possible to provide a spherical surface acoustic wave element that can contribute to the above.

Further according to the invention, it is possible to provide energy while preventing leakage, surface acoustic wave element and the rotation angle measurement equipment can achieve a compact gyro which utilizes the surface acoustic wave, such as a planar gyro.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but before that, an outline of a spherical surface acoustic wave element which is a premise of the present invention will be described. In the following description, the same parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 21 is a schematic diagram showing a configuration of a general spherical surface acoustic wave element. The spherical surface acoustic wave element 50 includes a spherical member 51 having a surface acoustic wave propagation path and an interdigital electrode 52 for excitation.

The spherical member 51 is a three-dimensional substrate having a surface acoustic wave propagation path. The propagation path of the surface acoustic wave can be formed, for example, by sputtering a thin film 51b of a piezoelectric material ZnO on the surface of a spherical glass member 51a. As the spherical member 51, in the case of using quartz or LiNbO ₃ which is a piezoelectric crystal, a propagation path can be formed without using the thin film 51b of the piezoelectric material. Piezoelectric crystals such as quartz have a specific path serving as a propagation path for surface acoustic waves. The number of paths varies depending on the crystal form. For example, in the case of quartz, it is an equator path (hereinafter referred to as “Z-axis cylinder”) with the C axis as the ground axis. In the case of LiNbO ₃ , it has been confirmed that 10 paths exist. In the case of a crystal called a BSO crystal, there are four paths.

  The interdigital electrodes 52 for excitation can excite surface acoustic waves in the propagation path on the surface of the spherical member 51 by applying an RF (high frequency) signal of a constant frequency from a high frequency signal source.

  The spherical surface acoustic wave element as described above is an element utilizing the fact that the excited surface acoustic wave circulates in a strip shape along the diameter of the spherical member. And it can be used as described in the following (i) and (ii).

  (I) The spherical surface acoustic wave element can be propagated while maintaining the phase wavefront of the surface acoustic wave by adjusting the balance between the diffraction effect of the surface acoustic wave and the geometric characteristics of the spherical member. That is, the surface acoustic wave can be propagated as a beam. In particular, when the three-dimensional substrate is a spherical member and isotropic, it can be set so that the phase wavefront of the surface acoustic wave is perpendicular to the circulation path at any location of the circulation path. The calculation method of this setting condition is already well known. However, in the following embodiments, it is not always necessary to make this setting, and the beam width may change to some extent.

  (Ii) When a unidirectional interdigital electrode is not used as the excitation interdigital electrode, surface acoustic waves are excited in both directions substantially perpendicular to the interdigital electrode. Therefore, the generated surface acoustic wave circulates around the surface of the spherical member and can form a standing wave. The interdigital electrode leaks the propagating surface acoustic wave to the measurement circuit as electric energy, but there is almost no electric energy lost when the surface acoustic wave passes through the interdigital electrode. Therefore, the surface acoustic wave can be continuously circulated around the propagation path several tens of times or several hundred times. Furthermore, if a high frequency signal is input for a time longer than the time for which the surface acoustic wave makes one round, the standing wave can be generated while being amplified during that time. Each of the following embodiments will be described by taking as an example a case where a standing wave is formed from the viewpoint of easily generating a large amplitude (a case where a unidirectional interdigital electrode is not used as an excitation interdigital electrode). However, the standing wave is not essential to the present invention, and it goes without saying that a unidirectional interdigital electrode may be used.

  This is the end of the description of the general spherical surface acoustic wave element that is the premise of each embodiment of the present invention.

Subsequently, each reference example and each embodiment of the present invention will be described.

<First Reference Example >
FIG. 1 is a schematic diagram showing a configuration of a rotational angle measuring device for a spherical surface acoustic wave device according to a first reference example of the present invention. This rotational angle measuring device includes a spherical surface acoustic wave element 10, a high-frequency signal source 20, and signal intensity measuring units 21A and 21B.

  Here, the spherical surface acoustic wave element 10 includes a spherical member 11, a standing wave excitation interdigital electrode 12, a surface acoustic wave perturbation body 13, and detection interdigital electrodes 14 </ b> A and 14 </ b> B.

  The spherical member 11 is a three-dimensional substrate having a propagation path capable of propagating a surface acoustic wave, and here, a quartz crystal (piezoelectric crystal) having a diameter of 10 mm is used. The propagation path has an annular surface made of a continuous curved surface, and a circular path for circulating the surface acoustic wave generated by the interdigital transducer 12 is provided on the annular surface.

  The interdigital electrode 12 for standing wave excitation is provided in contact with the surface of the spherical member 11, and the electric field of the RF signal is applied to the spherical member in accordance with a constant frequency RF signal (driving signal) input from the high-frequency signal source 20. 11 is applied to the propagation path of the surface, and has a function of exciting and propagating the surface acoustic wave on the surface of the spherical member 11. More specifically, the interdigital electrode 12 for standing wave excitation is formed on the z-axis cylinder of quartz that is the spherical member 11 and excites the surface acoustic wave to be excited in both the left and right directions, so that it is generated as the standing wave SAW1. The standing wave SAW1 is propagated as a belt-like beam that goes around the surface of the sphere, but it is not necessary to create a complete beam. This is because even if the beam width changes to some extent, there is no significant effect on the measurement of the rotation angle. For example, it is sufficient that the width of the beam diffuses throughout the spherical member 11 and it is difficult to fix the element, or there is no trouble such as causing a nonlinear effect due to the concentration of the beam. In order to design a surface acoustic wave element that satisfies these conditions, the wavelength of the surface acoustic wave excited by the interdigital electrode 12 for exciting the standing wave should be set to 1/30 or less of the diameter of the spherical member 11. desirable. The overlapping width of the interdigital electrode 12 for standing wave excitation (or the beam width of the surface acoustic wave beam immediately after being excited by the interdigital electrode 12 for standing wave excitation) is 5 minutes of the diameter of the spherical member 11. It is desirable to make it 1 or less.

  The surface acoustic wave perturbation body 13 propagates the standing wave SAW1 of the surface acoustic wave in a direction different from the propagation direction of the propagation path according to the rotational motion of the spherical member 11, and specifically, the standing wave. For example, a thick gold film having a density higher than that of the spherical member 11 is arranged at the position of the antinode of the SAW 1. This surface acoustic wave perturbation body 13 can be produced as follows. That is, a film of a gold chrome film (gold 300 nm, chromium 50 nm or so) is formed on the circulation path, and then the gold film and the chrome film are etched by a photolithography process so as to leave a pattern of the antinodes of the standing wave SAW1. And create. This photolithography process can be easily carried out because an optical system having a focal point on the sphere surface has already been developed. From the viewpoint of efficiently exciting the perturbation surface acoustic wave SAW2 when the spherical member 11 rotates, it is desirable that the surface acoustic wave perturbation body 13 is made of a material having as high a density as possible.

  The detection interdigital electrodes 14A and 14B (surface acoustic wave detection means) detect the surface acoustic wave SAW2 propagated in different directions by the surface acoustic wave perturbation body 13 by the piezoelectric effect of the spherical member 11, and detect the signal intensity. It is possible to output to the measurement units 21A and 21B. The detection interdigital electrodes 14A and 14B are formed in the traveling direction of the surface acoustic wave SAW2 propagating in different directions and at positions sandwiching the circulation band of the standing wave SAW1 of the surface acoustic wave. That is, the surface acoustic wave SAW2 propagated in different directions does not necessarily have to go around.

  On the other hand, the high-frequency signal source 20 is a signal source that outputs an RF signal having a constant frequency and applies the obtained RF burst signal to the interdigital electrode for standing wave excitation. The period of the sine wave in the RF signal is set to 1 / integer of the round time Tc required for the surface acoustic wave to make one round of the round path of the spherical member 11. Thereby, by applying the RF burst signal for a time longer than the circulation time Tc, it is possible to excite a surface acoustic wave having a large vibration amplitude and a standing wave having a large amplitude.

  The signal intensity measuring units 21A and 21B measure the rotation angle of the spherical member 11 from the intensity of the detection signal based on the detection signals output from the detection interdigital electrodes 14A and 14B, respectively. As a detection signal, an intensity signal substantially proportional to the angular velocity of rotation is observed, and the rotation angle is measured by time integration.

  The spherical surface acoustic wave element 10 as described above may be formed as shown in FIG. The interdigital electrode only needs to apply an electric field to the piezoelectric material to excite an elastic wave or to electrically receive an electric field generated by the piezoelectric material. Therefore, a structure in which the interdigital electrode 31 is formed so as to be opposed to the spherical member 11 in the gap portion of the mold base 30 close to the spherical member 11 may be used. A manufacturing method of such a structure is established by a semiconductor or micromachine technology. It is also possible to realize the interdigital electrode formed separately on the concave surface by approaching the three-dimensional substrate. Since it is not necessary to create a physical structure of the circulation path, the propagation of the surface acoustic wave is less reflected and less attenuated.

  Next, a rotation angle measurement method using the rotation angle measurement device for the spherical surface acoustic wave element configured as described above will be described.

  The high frequency signal source 20 generates and outputs an RF signal having a constant frequency, thereby inputting the RF burst signal to the interdigital transducer 12 for excitation. The period of the sine wave in the RF burst signal is adjusted so that the excited surface acoustic wave SAW1 is 1 / integer of the circulation time Tc required for one round of the circulation path of the spherical member 11, and the RF burst The entire signal is applied for a time longer than the circulation time Tc.

  When an RF signal is applied to the interdigital transducer 12 for excitation, surface acoustic waves SAW11 and SAW12 that circulate in opposite directions on the surface of the spherical member 11 are excited as shown in FIG. Is done.

  Here, the surface acoustic waves SAW11 and SAW12 are set to form a standing wave SAW1 on the circuit path by causing the surface acoustic waves SAW11 and SAW12 to rotate to interfere with each other. In the standing wave SAW1, the position where the respective phases of the surface acoustic waves from the opposite circulation directions on the circuit path are equal becomes antinode, and the amplitude increases. In addition, a node is formed at a position where the phase is shifted by 90 degrees from the antinode position, and is canceled by the interference of the surface acoustic waves SAW11 and SAW12 from the opposite circulation directions, and the amplitude becomes zero. Note that the time required for one round is constant even when the three-dimensional substrate is isotropic or has anisotropy like a crystal during multiple rounds. Therefore, a standing wave can be formed, and the positions of the antinodes and nodes of the standing wave SAW1 are unchanged.

  On the other hand, the thick gold film of the surface acoustic wave perturbation body 13 is formed at the antinode of the standing wave SAW1, as shown in FIG. Here, the surface of the spherical member 11 vibrates so as to alternate between positions (a) and (b) every ½ period of the standing wave SAW1. The surface acoustic wave perturbation body 13 realizes a fine vibration weight function.

  Then, the surface acoustic waves SAW11 and SAW12 constituting the standing wave SAW1 pass through the interdigital transducer 12 for each circulation cycle Tc and circulate around the surface of the spherical member 11. The surface acoustic waves SAW11 and SAW12 are collectively represented as SAW1 in FIG.

  In this state, when the spherical surface acoustic wave element 10 rotates according to the rotational movement of the external object to which the element is attached, the inertial force is in a direction different from the vibration of the thick gold film of the surface acoustic wave perturbing body 13. Works. This inertial force is generally called Coriolis force. When this inertial force acts on the vibration of the gold thick film, the antinode of the oscillating standing wave vibrates in an elliptical shape, and for example, the surface acoustic wave SAW2 is excited in a direction different from the surface acoustic wave SAW1. . The surface acoustic wave SAW2 excited here is a Rayleigh wave. In the Rayleigh wave, as shown in FIG. 5, near the surface of the solid material, the displacement of the material becomes a vertically long ellipse, and the displacement direction of the surface at the uppermost displacement point and the propagation direction of the Rayleigh wave are reversed. However, the present invention is not limited to Rayleigh waves, as long as energy is concentrated and propagated to the surface of the three-dimensional substrate.

  In any case, every time the surface acoustic wave SAW1 passes through the surface acoustic wave propagation body 13 according to the rotational motion of the spherical surface acoustic wave element 10, a Rayleigh wave is generated in a direction different from the propagation direction of the surface acoustic wave SAW1. A surface acoustic wave SAW2 is excited. The surface acoustic wave SAW2 is received by the detection interdigital electrode 14A or 14B depending on the direction of the rotational motion. When received, the detection signal of the surface acoustic wave SAW2 is output to the corresponding signal intensity measurement unit 21A or 21B.

  Based on the detection signal, the signal intensity measuring unit 21A or 21B can measure the rotation angle of the spherical surface acoustic wave element from the intensity of the detection signal.

In the present invention, the detection signal of the surface acoustic wave propagating in different directions due to the perturbation due to the rotation of the three-dimensional substrate has a property of being output with an intensity corresponding to the rotation speed of the three-dimensional substrate, and It does not change the output (intensity) according to the direction in static space. The rotated angle is obtained by integrating the rotational speed with time.

  Here, the measurement procedure of the rotation angle described above will be described in detail with reference to the time chart of FIG. In FIG. 6, the horizontal axis represents time, and the vertical axis represents signal intensity.

In this reference example , the SN ratio is improved by detecting surface acoustic waves that have propagated in different directions after cutting the excitation RF signal.

  The frequency of the surface acoustic wave SAW2 that the excitation RF signal is excited by the surface acoustic wave perturbation body 13 is a frequency that is at least included in the standing wave excitation RF signal. For this reason, the standing wave excitation RF signal enters the detection interdigital electrodes 14A and 14B or their signal lines to generate noise. Therefore, in order to improve the SN ratio, measurement is performed by the following procedures (i) to (iii).

  (I) First, as shown in FIG. 6A, an RF signal is applied for a predetermined time to excite a standing wave (time t1). In this case, it is desirable that the circulation time Tc in which the surface acoustic wave SAW1 circulates in the circulation path is an integral multiple of the period of the RF signal. This is because the amplitude intensity of the standing wave can be increased by making the signal period of the RF burst signal to be excited longer than the circulation time Tc.

(Ii) Next, the excitation RF signal is disconnected (time t2). In the case of the present reference example , the energy of the surface acoustic wave is stored over the circulation path, and the standing wave exists even after the excitation RF signal is cut. As a result, after the excitation RF signal is cut off, it is possible to measure the intensity of the detection signal output from the detection interdigital electrode 14A or 14B as the rotation angle measurement target. However, as shown in FIG. 6B, the intensity of the standing wave of the surface acoustic wave SAW1 decays exponentially with time.

  (Iii) Next, according to the rotational motion of the spherical member 11 from time t0 to t3 as shown in FIG. 6C, the surface acoustic wave SAW2 propagated in different directions as shown in FIG. 6D. Is output from the detection interdigital electrode to the signal intensity measuring unit 21A or 21B.

  Even when the rotation speed is constant, the detection signal is observed with time decay according to the attenuation of the standing wave intensity. However, the signal intensity measuring units 21A and 21B may adopt the value of the time with the largest amplitude as the intensity of the detection signal, as indicated by an arrow a in FIG. If the intensity of the detection signal is calibrated with the standing wave intensity of the surface acoustic wave SAW1 in order to perform higher-precision measurement, it becomes possible to prevent the fluctuation of the standing wave intensity from affecting the measurement result. . In addition to calibrating the amplitude of the detection signal, the rotation angle can be measured with higher accuracy by integrating the calibrated amplitude with time.

As described above, according to the present reference example , the surface acoustic wave SAW 1 is excited on the surface of the spherical member 11, and the elasticity that propagates in a direction different from the propagation direction of the surface acoustic wave SAW 1 according to the rotational motion of the spherical member 11. Unlike the conventional planar surface acoustic wave gyro, the configuration for detecting the surface wave SAW2 eliminates the need for a reflector, and thus a small gyro using surface acoustic waves can be realized. Moreover, since it is realized by a spherical surface acoustic wave element, it is possible to prevent leakage of energy as in a planar gyro.

  Further, since the spherical member 11 has an annular surface made of a continuous curved surface, the surface acoustic wave can be circulated on the circulation path, and the element can be reduced in size. In addition, the surface acoustic wave to be excited is made to be a standing wave to increase the intensity, and the surface acoustic wave perturbing body 13 is provided with a structure in which substances having different masses are arranged, so that the propagation direction of the surface acoustic wave can be efficiently changed. Can be changed. Thereby, a rotation angle can be calculated | required efficiently.

  In addition, in the surface acoustic wave device, the surface acoustic wave to be excited is excited under the condition determined by the diameter of the spherical member, and is propagated in a beam shape without being diffracted and detected by the interdigital electrode for detection. be able to. Therefore, the problem of conventional planar gyros, “surface wave“ diffraction ”is output to the interdigital electrodes for detection, and the surface wave signals excited by the perturbation due to the rotation of the three-dimensional substrate are buried. Therefore, it is possible to prevent a phenomenon that makes measurement difficult due to a decrease in the SN ratio.

It is also possible to relatively increase the SN of the detection signal generated with the rotation by installing the interdigital electrode for detection near the opposite side of the three-dimensional substrate with respect to the surface acoustic wave perturbed body. is there.

<First embodiment>
FIG. 7 is a schematic view showing a configuration of a spherical surface acoustic wave element applied to the rotation angle measuring apparatus according to the first embodiment of the present invention. The same parts as those in FIG. The parts are marked with alphabetic subscripts, and the different parts are mainly described here. In the following embodiments, the same description is omitted.

This embodiment is a modification of the first reference example , and as shown in FIG. 7A, there are six rotation directions (detection directions x1, x2, y1) of three rotation axes x, y, z orthogonal to each other. , Y2, z1, z2) from the viewpoint of being able to detect the rotation angle, as shown in FIG. 7B, the spherical member 11 includes two propagation paths A, B orthogonal to each other and the respective propagation paths A. , B and a circulation path formed on B. At least one surface acoustic wave perturbation body 13x, 13y, 13z is formed in each circulation path, and a total of three are formed. Further, the detection interdigital electrodes 14x1, x2, y1, y2, z1, and z2 having the corresponding subscripts x, y, and z are propagated along the propagation paths A and B so as to sandwich the surface acoustic wave perturbations 13x, 13y, and 13z. It arrange | positions on the circumference path different from the upper circumference path. The detection orientations x1 and x2 correspond to two rotation directions when the spherical member 11 rotates around the x axis. The same applies to the other detection directions y1, y2, z1, and z2.

  Here, the spherical surface acoustic wave element 10 includes a spherical member 11, interdigital electrodes 12A and 12B for exciting standing waves, surface acoustic wave perturbations 13x, 13y, and 13z, and interdigital electrodes for detection 14x1, 14x2, and 14y1, 14y2, 14z1, and 14z2.

  The spherical member 11 has a plurality of circulation paths. In this embodiment, the interdigital electrodes 12A and 12B for exciting the standing wave excite the surface acoustic waves in the propagation paths A and B, respectively.

  The interdigital electrodes 12A and 12B for exciting the standing wave excite standing waves SAW1A and SAW1B (not shown) of the surface acoustic waves on the propagation paths A and B, respectively.

  The surface acoustic wave perturbation body 13x is stationary on the propagation path A so that the surface acoustic wave is individually propagated toward the interdigital electrodes 14x1 or 14x2 for detection according to the rotational movement of the spherical member 11 on the x axis. It is a thick film arranged at the position of the antinode of the wave SAW1A.

  The surface acoustic wave perturbation body 13y is stationary on the propagation path A so that the surface acoustic wave propagates individually toward the interdigital electrodes 14y1 or 14y2 for detection according to the rotational movement of the spherical member 11 in the y-axis. It is a thick film arranged at the position of the antinode of the wave SAW1A.

  The surface acoustic wave perturbation body 13z is stationary on the propagation path B so that the surface acoustic wave is individually propagated toward the interdigital electrodes 14z1 or 14z2 for detection according to the rotational movement of the spherical member 11 in the z-axis. It is a thick film disposed at the position of the antinode of the wave SAW1B.

  Originally, it is desirable to form 13z on the propagation path A, but forming a plurality of surface acoustic wave perturbations on the propagation path A is not preferable from the viewpoint of exciting a stable standing wave. It is formed at a shifted position.

  The detection interdigital electrodes 14x1 and 14x2 detect surface acoustic waves SAW2x1 and SAW2x2, respectively, and output detection signals to the signal intensity measuring units 21A and 21B. Interdigital electrodes for detection 14y1, 14y2 and 14z1, 14z2 have the same functions as 14x1, 14x2, and detect surface acoustic waves SAW2y1, SAW2y2, SAW2z1, SAW2z2 propagated in different directions, and signal intensity measuring units not shown Can be output.

On the other hand, the high-frequency signal source 20 and the signal intensity measuring units 21A, 21B,... Are not shown, but are configured in the same manner as in the first reference example . That is, the high-frequency signal source 20 can apply an RF signal having a constant frequency to the interdigital electrodes 12A and 12B for standing wave excitation. Further, the signal intensity measuring units 21A, 21B,... Are respectively rotated based on the detection signals output from the detection interdigital electrodes 14x1, 14x2, 14y1, 14y2, 14z1, and 14z2, and the rotation directions x1 of the corresponding suffixes x1 to z2. , X2, y1, y2, z1, z2 can be measured. That is, one signal intensity measuring unit 21A, 21B,... Is provided for each detection interdigital electrode 14x1,.

  Next, a rotation angle measurement method using the rotation angle measurement device for the spherical surface acoustic wave element configured as described above will be described.

  Now, it is assumed that an RF signal is inputted to the interdigital electrodes 12A and 12B for standing wave excitation from a high-frequency signal source (not shown).

  The interdigital electrodes 12A and 12B for exciting the standing waves excite the standing waves SAW1A and SAW1B (not shown) of the surface acoustic waves on the propagation paths A and B, respectively, according to the input RF signals.

  In this state, when the spherical surface acoustic wave element 10 rotates in the x1 or x2 direction with the x axis as the central axis, the surface acoustic wave perturbation body 13x detects the surface acoustic wave SAW1A in accordance with this rotational motion. Alternatively, the propagation direction is changed toward 14 × 2.

  For example, when rotating in the x1 direction around the x axis, the surface acoustic wave propagates in the direction of the detection interdigital electrode 14x1. The detection interdigital electrode 14x1 detects surface acoustic waves propagated in different directions and outputs a detection signal to the signal intensity measurement unit 21A. The signal intensity measuring unit 21A can measure the rotation angle in the x1 direction based on the detection signal.

  Similarly, when rotating in the x2 direction around the x axis, the surface acoustic wave SAW1A propagates in the direction of the detection interdigital electrode 14x2. The detection interdigital electrode 14x2 outputs a detection signal to the signal intensity measuring unit 21B, and the signal intensity measuring unit 21B can measure the rotation angle in the x2 direction.

  Similarly, the rotation angle along the rotation directions x1, x2, y1, y2, z1, and z2 is detected in accordance with the rotational motion around the rotation axes x, y, and z of the spherical surface acoustic wave element 10. Can do.

As described above, according to the present embodiment, in addition to the effects of the first reference example , a plurality of surface acoustic waves are generated, and the surface acoustic waves are individually excited according to the rotational movement of the spherical member 11 in the three axial directions. Therefore, it is possible to provide a device that can detect a three-dimensional rotation direction and can perform three-axis measurement. Specifically, by using the two propagation paths A and B, the rotation angle can be detected for all three axes. Any rotation in three dimensions can be detected independently of the three rotations of the x, y, and z axes. Even when the circulation path is not vertical, the rotation amount of each direction can be obtained by calculation.

  In the above embodiment, in order to avoid crosstalk of surface acoustic waves leaking to the surface of the spherical member 11, RF signals having different frequencies are applied to the interleaved electrodes 12A and 12B for standing wave excitation. Is desirable.

  In the above embodiment, eight interdigital electrodes 12A to 12B and 14x1 to 14z2 are used. In order to prevent such a large number of interdigital electrodes from being formed, the configuration shown in FIG. 8 can be employed. In this configuration, the above described standing wave excitation interdigital electrodes 12A and 12B are omitted, and the detection interdigital electrodes 14y1, 14y2, 14z1, and 14z2 are arranged on the propagation path A or B, respectively. The electrodes 14y1, 14y2, 14z1, and 14z2 have the function of interdigital electrodes for standing wave excitation. Specifically, a surface acoustic wave perturbation body 13 yz is formed at the intersection of the propagation paths A and B, and the detection interdigital electrodes 14 y 1, 14 y 2, 14 z 1, and 14 z 2 are connected to the propagation path A so as to sandwich the surface acoustic wave perturbation body 13 yz from four directions. , B. Thus, for example, a high-frequency signal is applied to the interdigital electrode 14y1 for detection to excite a standing wave, which is excited and propagated in different directions by the surface acoustic wave perturbation body 13yz and then propagated in different directions. The surface wave can be detected by the interdigital electrode 14z1 or 14z2 for detection. That is, with the configuration shown in FIG. 8, since the interdigital electrodes 12A and 12B dedicated to standing wave excitation can be omitted, the number of interdigital electrodes to be formed can be reduced to six. Can be simplified.

In this embodiment, the propagation path B is perpendicular to the propagation path A, and surface acoustic waves are excited and circulated in the propagation paths A and B. However, in the case of quartz, the propagation path B Attenuation accompanying laps is large. Therefore, it is more preferable to use lithium niobate (LiNbO ₃ ) or lithium tantalate as the spherical member 11.

<Second Embodiment>
FIG. 9 is a schematic diagram showing a configuration of a surface acoustic wave perturbation body applied to a spherical surface acoustic wave element according to the second embodiment of the present invention.

The present embodiment is a modification of the first reference example or the first embodiment, and uses “mass formation” and / or “mass defect” as the surface acoustic wave perturbing body 13.

  Here, the surface acoustic wave perturbation body 13 is periodically formed in a partial region of the circumferential path of the surface acoustic wave and at the position of the antinode of the standing wave. Or it is comprised from the structure from which height differs. For example, the surface acoustic wave perturbation body 13 is formed in the propagation path by a material having an elastic constant different from that of the spherical member 11. This may be formed by holes or grooves by etching of the spherical member 11 or the piezoelectric film formed on the surface thereof, or conversely, a convex structure may be formed on the member.

  Specifically, as shown in FIGS. 9A to 9C, the surface acoustic wave perturbing body 13 can be formed by a convex structure, a concave structure, or a composite structure.

  In the case of the convex structure shown in FIG. 9A, perturbation is applied to the mass forming unit 13a with respect to a certain rotation operation.

  In the case of the concave structure shown in FIG. 9B, the mass defect portion 13b adds a perturbation to a phase opposite to that of the convex structure for a certain rotation operation. Here, the mass defect 13b having a concave structure can be created by the following procedures (i) to (iii).

  (I) A resist is patterned on the surface of the spherical member 11 such as a crystal sphere so that the antinode position of the standing wave is exposed.

  (Ii) The exposed belly position of the spherical member 11 is etched by hydrofluoric acid treatment.

  (Iii) A dimple-like diffusion pattern is formed by peeling off the resist to create the mass defect portion 13b. In this method, a process for forming a different material is not required.

  In the case of the composite structure shown in FIG. 9C, the convex structure and the concave structure are overlapped.

  The arrangement of the mass forming portion 13a and the mass defect portion 13b as described above is as shown in FIG. That is, in one surface acoustic wave (excitation wave) along the horizontal direction of the paper surface, the mass defect portion 13b is disposed on the antinode of the low position, and the mass forming portion 13a is disposed on the antinode of the high position. In other words, the mass forming portion 13a is arranged one for each wavelength λ with respect to one surface acoustic wave. Similarly, one mass defect portion 13b is arranged for each wavelength λ with respect to one surface acoustic wave. In addition, each part 13a, 13b is not arrange | positioned in the node position of a standing wave.

  On the other hand, in the vertical direction of the paper surface, the mass forming portions 13a are arranged one by one at intervals of λ ′. Similarly, the mass defect portions 13b are arranged one by one at intervals of λ ′. With this arrangement, a surface acoustic wave (Rayleigh wave) having one wavelength λ ′ is excited along the vertical direction of the paper surface.

  In addition, as shown in the figure, the mass forming part 13a and the mass defect part 13b are related to the surface acoustic wave excited and the surface acoustic wave excited in a different direction by perturbation with respect to each other at half wavelength (λ / 2), They are arranged in a lattice pattern at intervals of (λ ′ / 2), and a perturbation effect can be generated for each half wavelength.

According to the above configuration, in addition to the effects of the first reference example or the first embodiment, the mass forming portion 13a and the mass defect portion 13b made of substances having different densities and heights are used as the surface acoustic wave perturbing body 13. By providing the arranged structure, the surface acoustic wave can be efficiently excited by perturbation. Thereby, it becomes possible to obtain | require a rotation angle efficiently. In particular, in the case of a composite structure, since a perturbation effect can be generated for each half wavelength, the signal intensity of the surface acoustic wave excited by the perturbation can be further increased.

< Third Embodiment>
FIG. 11 is a plan view showing a configuration of a surface acoustic wave perturbation body applied to a spherical surface acoustic wave element according to a third embodiment of the present invention.

This embodiment is a modification of the first reference example or the first to second embodiments, and from the viewpoint of exciting a surface acoustic wave excited by perturbation in an oblique direction, as shown in FIG. With respect to the propagation direction d of the surface acoustic wave, the mass forming portions 13a of the surface acoustic wave perturbing body 13 are arranged in an oblique direction by an angle θ.

  The thus formed elastic surface perturbation body 13 propagates the surface acoustic wave SAW1 in an oblique direction by an angle θ from the circulation direction. Further, if the mass defect portion 13b is arranged between the mass forming portions 13a as described above to form the composite surface acoustic wave perturbation body 13 as shown in FIG. 12, the mass defect portion 13b is more efficient. In addition, the surface acoustic wave can be excited by perturbation.

According to the above structure, in addition to the effects of the first reference example or the first and second embodiments, the surface acoustic wave can be excited in an oblique direction, so that each interdigital electrode of the spherical member 11 It is possible to freely design the arrangement of the circulation path. For example, as shown in FIG. 13, a rotation angle measuring device for the spherical surface acoustic wave element 10 can be easily created even with a spherical member 11L made of a crystal such as LiNbO ₃ . In the LiNbO ₃ crystal, the circulation path of the surface acoustic wave is specified by the crystal form. For example, the orbital zone of SAW1 serving as the Z-axis cylinder and the orbital zone of SAW2 inclined to the Z-axis cylinder are specified by the crystal form. For this reason, it is necessary to propagate the surface acoustic wave SAW2 in a direction other than perpendicular to the propagation path of the standing wave SAW1 of the surface acoustic wave. In such a case, by using the surface acoustic wave perturbation body 13 described in the present embodiment, the surface acoustic wave can be excited by the perturbation along the propagation path of the surface acoustic wave.

  In addition, when a surface acoustic wave whose propagation direction has been changed by a surface acoustic wave perturbant is propagated to another propagation path, the surface acoustic wave perturbation is performed so that the surface acoustic wave after the change of the propagation direction is propagated as a beam. By designing the body, it is possible to take out as a large signal without diffusing the energy of the surface acoustic wave after the change. For this reason, the problem of conventional planar gyros, “surface diffraction of surface acoustic waves” is output to the interdigital electrodes for detection, and the signals of surface acoustic waves excited by perturbations due to the rotation of the planar substrate are buried. It is possible to prevent a phenomenon that makes measurement difficult as the SN ratio decreases.

  Furthermore, when the vibration period of the surface acoustic wave excited with the rotation of the three-dimensional substrate is 1 / integer of the lap time required to circulate the circulatory path, the surface acoustic wave energy is more stably propagated. It can be maintained on the road. In order to satisfy this condition, a thin film for adjusting the circulation time of the surface acoustic wave excited along with the rotation of the three-dimensional substrate may be formed on the circulation path.

< Fourth Embodiment>
FIG. 14 is a schematic diagram showing the configuration of a rotational angle measuring device for a spherical surface acoustic wave element according to the fourth embodiment of the present invention.

The present embodiment is a modification of the first reference example or the first to third embodiments, and the resonance state of the surface acoustic wave is maintained by adjusting the frequency of the RF signal of the high-frequency signal source 20s, which is always sufficient. A standing wave with a high intensity is generated.

  This rotational angle measuring device includes a spherical surface acoustic wave element 10, a high frequency signal source 20s, a switching unit 22, a changeover switch 23, a surface acoustic wave intensity measuring unit 24, a resonance state determining unit 25, a frequency adjusting unit 26, and a signal intensity (not shown). A measuring unit is provided.

  Here, the interdigital electrode 12 s for standing wave excitation in the spherical surface acoustic wave element 10 is provided in contact with the surface of the spherical member 11, and a constant frequency RF input from the high frequency signal source 20 s via the changeover switch 23. According to the signal (driving signal), an RF signal electric field is applied to the propagation path on the surface of the spherical member 11 to excite surface acoustic waves SAW11 and SAW12 that circulate in opposite directions on the surface of the spherical member 11. ing.

  Further, the interdigital electrode 12s for standing wave excitation detects a synthetic wave SAW1 (not shown) of the circulating surface acoustic waves SAW11 and SAW12 when examining the frequency of the RF signal that can generate a standing wave. The loop detection signal is output to the surface acoustic wave intensity measurement unit 24 via the changeover switch 23.

  On the other hand, the high-frequency signal source 20 s is a signal source that intermittently outputs an RF signal having a constant frequency and applies the obtained RF burst signal to the interdigital electrode 12 s for standing wave excitation via the changeover switch 23. . The high frequency signal source 20s is controlled by the frequency adjustment unit 26, and it is preferable to use, for example, a digital signal generator from the viewpoint of fine adjustment of the frequency.

  The switching unit 22 has a function of controlling connection or insulation of the changeover switch 23.

  The changeover switch 23 is controlled by the changeover unit 22 to connect the interdigital electrode 12s for standing wave excitation to the high-frequency signal source 20s or the surface acoustic wave intensity measurement unit 24, or to insulate from both 20s and 24.

  The surface acoustic wave intensity measurement unit 24 has a function of measuring the intensity of the surface acoustic wave SAW1 based on the circumference detection signal input from the interleaved electrode 12s for standing wave excitation via the changeover switch 23, and the obtained For example, a digital oscilloscope can be used.

  Based on the intensity measurement value output from the surface acoustic wave intensity measurement unit 24, the resonance state determination unit 25 determines whether or not to adjust the frequency of the RF signal and the determination result indicating the adjustment. And a function of controlling the frequency adjusting unit 26. The resonance state determination unit 25 uses an electronic computer here, and issues an instruction to change the frequency of the RF signal to the frequency adjustment unit 26 using GPIB or the like. The instruction to change the frequency is to promptly obtain a resonance state.When the frequency is changed in the increasing or decreasing direction, and the current intensity measurement value increases from the previous intensity measurement value, the next change is also made. It is preferable to put out in the same direction.

  The frequency adjustment unit 26 is controlled by the resonance state determination unit 25 and adjusts the frequency of the RF signal of the high-frequency signal source 20s. Note that the high-frequency signal source 20s and the frequency adjusting unit 26 can be integrally configured using digital parts.

Next, the resonance state of the surface acoustic wave and the measurement method will be described. Note that the method for measuring the rotation angle of the spherical surface acoustic wave element is the same as in the first reference example and the first to third embodiments, and is omitted, and a method of adjusting to the resonance frequency is mainly described. To do.

  Here, the “resonant state” means a state in which the time for which the surface acoustic wave circulates around the circular path of the spherical surface acoustic wave element is an integral multiple of the vibration period of the surface acoustic wave. In the resonance state, when a high frequency signal is applied for a time longer than one round, surface acoustic waves propagating in opposite directions can be amplified, and as a result, a strong standing wave can be excited. The reason is that an electric field that amplifies the vibration of the surface acoustic wave is applied to the interdigital electrode for standing wave excitation in the same phase as the surface acoustic wave that has already circulated.

  On the other hand, when the frequency is not within the resonance state, that is, when a frequency at which the resonance state cannot be created is applied to the interdigital electrode for standing wave excitation, the surface acoustic wave having a different phase is applied to the surface acoustic wave in circulation. The surface acoustic wave that already exists is canceled out. For this reason, when the resonance state is deviated, it is impossible to form a standing wave having a sufficient strength to detect a surface acoustic wave excited in a different direction by perturbation.

    Such a resonance state is affected by the ambient temperature, humidity, surface condition, and the like. For example, the resonance state is broken by changing the circumferential speed (frequency) of the surface acoustic wave SAW1 depending on the temperature. Conversely, the resonance state can be maintained by adjusting the frequency (period) of the surface acoustic wave SAW1. The frequency of the surface acoustic wave SAW1 is changed according to the frequency of the RF signal. That is, by changing the frequency of the RF signal, the frequency of the surface acoustic wave SAW1 that maintains the resonance state can be adjusted.

  Since the intensity of the standing wave is strong in the resonance state, it can be determined whether or not the resonance state is obtained by measuring the intensity I ′ of the surface acoustic wave SAW1. That is, the intensity of the circulating surface acoustic wave is measured by the surface acoustic wave intensity measuring unit 24, and the obtained measurement intensity is compared with a reference intensity in a preset resonance state. When the measured intensity is lower than the reference intensity, it is determined that the resonance state has been lost. When deviating from the resonance state, the frequency of the RF signal output from the high-frequency signal source 20s is changed, and the intensity of the surface acoustic wave is measured again. It is possible to detect the resonance state by repeatedly changing the frequency of the RF signal until the measurement intensity becomes equal to the reference intensity.

  Further, when approaching the resonance state, the measured intensity value of the surface acoustic wave increases, and shows a maximum value in the resonance state. Therefore, the method of maintaining the resonance state is not limited to the method of comparing with the above-described reference intensity, but the frequency of the RF signal is swept in the direction in which the measured intensity value increases so that the measured intensity value of the surface acoustic wave is maximized. Alternatively, a method for controlling the frequency may be used.

  Alternatively, the standing wave interdigital electrode 12s may be separated into a standing wave excitation interdigital electrode 12t and an excitation wave intensity detecting interdigital electrode 12u as shown in FIG. Thereby, the switching part 22 and the changeover switch 23 can be omitted, and the configuration can be simplified. Further, it has an advantage that surface acoustic waves can be excited and detected continuously. Alternatively, the apparatus shown in FIG. 15 may be modified so that the interdigital electrode 12u for intensity detection is switched and connected to the high-frequency transmitter 20s or the surface acoustic wave intensity measuring unit 24. In this modification, the two interdigital electrodes 12t and 12u are driven together during standing wave excitation, and the interdigital electrode 12u for intensity detection may be used as shown in FIG. 15 when detecting the resonance state.

  Next, a procedure for maintaining a resonance state and generating a standing wave with sufficient strength in the rotation angle measuring apparatus configured as described above will be described with reference to the flowchart of FIG. The rotation angle measuring device shown in FIG. 14 is used.

  First, the frequency adjustment unit 26 adjusts the frequency of the RF signal of the high-frequency signal source 20s (s1). Next, the switching unit 22 controls the changeover switch 23 to connect the spherical surface acoustic wave element 10 and the high-frequency signal source 20s (s2). The high frequency signal source 20s generates an RF signal having a constant frequency and intermittently outputs the RF signal, thereby inputting the RF burst signal to the interdigital electrode 12s for excitation.

  The interdigital electrode 12s for standing wave excitation excites the surface acoustic waves SAW11 and SAW12 that circulate in opposite directions on the surface of the spherical member 11, and causes the surface acoustic waves SAW11 and SAW12 to circulate to interfere with each other. The standing wave SAW1 is generated in at least a part of (S3).

  Next, the switching unit 22 controls the changeover switch 23 to connect the spherical surface acoustic wave element 10 and the surface acoustic wave intensity measuring unit 24 (s4). Thereby, the interdigital electrode 12s for standing wave excitation detects the surface acoustic wave SAW1 that circulates, and outputs a circulatory detection signal to the surface acoustic wave intensity measuring unit 24.

  The surface acoustic wave intensity measurement unit 24 measures the intensity of the surface acoustic wave SAW1 based on the rotation detection signal (s5), and outputs the obtained measurement intensity value I ′ to the resonance state determination unit 25.

  The resonance state determination unit 25 determines whether or not to adjust the frequency of the RF signal based on the measured intensity value I ′. In the determination, the measured intensity value I ′ of the rotation detection signal is compared with the reference intensity value I of the surface acoustic wave in a preset resonance state.

  As a result of the comparison, if the measured intensity value I ′ and the reference intensity value I are equal, it is determined that the resonance state exists, and the process is terminated (s6 = Yes). Further, if the measured intensity value I ′ is lower than the reference intensity value I, it is determined that the resonance state is not established, and an instruction to change the frequency of the RF signal is issued to the frequency adjustment unit 26 so as to increase the measured intensity value I ′ (s6). = No).

  The change of the frequency of the RF signal as described above is repeated until the surface acoustic wave SAW1 enters a resonance state. Thereby, an RF signal having the adjusted frequency can be input, and a standing wave having sufficient intensity can be generated.

As described above, according to the present embodiment, in addition to the effects of the first reference example or the first to third embodiments, the resonance state of the surface acoustic wave is adjusted by adjusting the frequency of the RF signal of the high-frequency signal source 20s. It is possible to maintain and always generate a standing wave with sufficient intensity.

  Further, since the standing wave can be efficiently excited by adjusting the frequency of the RF signal, the vibration amplitude at the antinode of the surface acoustic wave perturbing body 13 can be increased. Therefore, when measuring the rotation angle, the intensity of the surface acoustic wave excited by the perturbation can be increased, and the measurement sensitivity can be improved.

< Fifth Embodiment>
FIG. 17 is a schematic diagram showing the structure of a spherical surface acoustic wave device according to the fifth embodiment of the present invention.

  Further, in the following description, the number of interdigital electrodes is an example, and the present invention includes a form in which the number of interdigital electrodes is changed in accordance with the number of propagation paths.

  The spherical surface acoustic wave element 110 includes interdigital electrodes 130A to 130D and surface acoustic wave perturbations 140A to 140D on a spherical member 11X having a plurality of propagation paths 120A to 120D capable of propagating surface acoustic waves. Yes.

  The spherical member 11X is a three-dimensional substrate having propagation paths 120A to 120D capable of propagating surface acoustic waves. As the spherical member 11X, a spherical member 11L made of a crystal such as LiNbO 3 may be used.

  The propagation paths 120 </ b> A to 120 </ b> D are a plurality of propagation paths that share two crossing areas where two arbitrary lines cross each other at two places or a single connection area connected at one place.

  Here, when two propagation paths intersect with each other, if the propagation paths are both circular paths, the propagation paths are said to “cross”. On the other hand, when two propagation paths intersect, if at least one of the propagation paths is not a circular path, the propagation path is said to be “connected”.

  Propagation paths 120A and 120B are circulation paths composed of continuous curved surfaces capable of circulating surface acoustic waves, and propagation paths 120A and 120B intersect each other.

  The propagation paths 120C and 120D are propagation paths in which surface acoustic waves do not circulate, and are connected to the propagation paths 120A and 120B.

  The interdigital electrodes 130A to 130D are formed on the propagation paths 120A to 120D, and excite surface acoustic waves on the surfaces of the propagation paths 120A to 120D according to the input drive signals, and the surface acoustic wave perturbations 140A to 140D. A surface acoustic wave whose propagation direction is changed by 140D is detected, and a detection signal is output.

The surface acoustic wave perturbations 140A to 140D have a function of perturbing the surface acoustic waves excited by the interdigital electrodes 130A to 130D and propagating the surface acoustic waves in directions different from the propagation directions of the propagation paths 120A to 120D, respectively. I have it. In the fifth to sixth embodiments, the surface acoustic wave perturbation body may be replaced with a surface acoustic wave diffractive body. That is, the surface acoustic wave perturbant and the surface acoustic wave diffractor are not distinguished from each other as long as they have a function of propagating the surface acoustic wave output to the input surface acoustic wave in different directions. At this time, the action of exciting the second surface acoustic wave from the first surface acoustic wave by the surface acoustic wave perturbing body is the action that the first surface acoustic wave by the surface acoustic wave diffractor is diffracted and propagates. Shall be replaced.

Here, the surface acoustic wave perturbations 140A, 140B, and 140D are formed in a connection region between the propagation path 120A and the propagation path 120C, a connection region between the propagation path 120B and the propagation path 120C, and a connection region between the propagation path 120B and the propagation path 120D, respectively. Thus, the surface acoustic wave perturbation body 140C is formed in the intersection region of the propagation path 120A and the propagation path 120B. Note that the propagation paths 120A and 120B also have a crossing region (not shown) on the back side of the paper in FIG. 17 (the two circular paths intersect at two points).
Next, the operation of the surface acoustic wave element 110 according to this embodiment will be described.

  Here, for the sake of simplicity, the surface acoustic waves SAWq1 and SAWq2 excited by the interdigital electrode 130C will be described as an example, but it goes without saying that other interdigital electrodes may play the same role.

  First, a high frequency signal is applied to the interdigital electrode 130C, and the surface acoustic waves SAWq1 and SAWq2 are excited so as to propagate in both directions on the propagation path 120C from both sides of the interdigital electrode 130C.

  The surface acoustic wave SAWq1 propagates on the propagation path 120C, the propagation direction is changed by the surface acoustic wave perturbation body 140A formed in the connection region, and propagates through the propagation path 120A. On the other hand, the surface acoustic wave SAWq2 propagates on the propagation path 120C, and propagates through the propagation path 120B with the propagation direction changed by the surface acoustic wave perturbation body 140B formed in the connection region.

  The surface acoustic wave SAWq1 goes around the propagation path 120A, and the surface acoustic wave SAWq2 goes around the propagation path 120B. At this time, the two surface acoustic waves SAWq1 and SAWq2 interact on the surface acoustic wave perturbation body 140C in the intersecting region and exchange energy with each other.

  As a result, for example, an adder circuit that outputs the interference output of the surface acoustic waves SAWq1 and SAWq2 from the interdigital electrode on one propagation path can be configured.

  Similarly, for example, when the surface acoustic wave SAWq2 that circulates in the propagation path 120B passes through the surface acoustic wave perturbation body 140D, the surface acoustic wave from the other propagation path 120D is propagated to the surface acoustic wave perturbation body 140D, and the surface acoustic wave By interacting (interfering) two surface acoustic waves on the perturbing body 140D, a switch for turning off propagation of the surface acoustic wave SAWq2 during circulation, an attenuator for attenuating, or an amplifier for amplifying can be configured. it can.

  As described above, according to the present embodiment, the configuration including the surface acoustic wave perturbation body that propagates the excited surface acoustic wave in a propagation direction different from the propagation direction in the connection region or the intersection region of the propagation path, Provided is a surface acoustic wave device that contributes to the realization of a surface acoustic wave circuit because it enables stable surface acoustic wave propagation and realizes interaction between surface acoustic waves in a region where a plurality of propagation paths overlap. be able to.

  Thereby, for example, a spherical surface acoustic wave system that realizes a signal transmission system via surface acoustic waves can be realized.

< Sixth Embodiment>
FIG. 18 is a schematic diagram showing the structure of a spherical surface acoustic wave device according to the sixth embodiment of the present invention.

This embodiment is a modification of the fifth embodiment. In addition to the function of changing the propagation direction of surface acoustic waves, the surface acoustic wave perturbations 140A1 to 140D1 receive instructions from external control means, It has a function of giving a perturbation that changes with time to a surface acoustic wave. The function of giving a time-dependent perturbation to a surface acoustic wave is, for example, a vibrator that vibrates with an electric signal. For example, as the type shown in FIG. 2, this vibrator has a structure in which interdigital electrodes are formed facing the surface acoustic wave perturbations 140A1 to 140D1 in the gap portion of the mold base material that is in close contact with the spherical member 11X. It is possible. However, it goes without saying that the surface acoustic wave may be perturbed with time by the rotational movement of the spherical member 11X.

Since the structure of other components is the same as that of the fifth embodiment, the description thereof is omitted.

  Next, the operation of the surface acoustic wave element 110 according to this embodiment will be described.

  Here, for the sake of simplicity, the surface acoustic waves SAWp1 and SAWp2 excited by the interdigital electrode 130A and the interdigital electrode 130B will be described as an example, but it goes without saying that other interdigital electrodes may play the same role. Yes.

  First, the surface acoustic wave SAWp1 is excited by the interdigital electrode 130A, and the surface acoustic wave SAWp2 is excited by the interdigital electrode 130B.

  The surface acoustic wave SAWp1 goes around the propagation path 120A, and the surface acoustic wave SAWp2 goes around the propagation path 120B.

  Next, the surface acoustic wave perturbation body 140C1 receives an instruction from the outside, and applies a time-varying perturbation to the surface acoustic wave SAWp1. As a result, the surface acoustic wave perturbation body 140C1 exchanges energy with the surface acoustic wave SAWp1, and propagates the surface acoustic wave SAWp1 in the propagation direction of the propagation path 120B.

  The surface acoustic wave SAWp1 that propagates through the propagation path 120B is combined with the surface acoustic wave SAWp2 that has previously propagated through the propagation path 120B, and propagates as the surface acoustic wave SAWp.

  As described above, according to the present embodiment, the two propagation paths 120A and 120B are propagated by giving a perturbation that changes with time in accordance with an instruction from the outside to the intersection region between the two propagation paths 120A and 120B. It is possible to realize a system in which the surface acoustic waves SAWp1 and SAWp2 that influence each other influence each other.

  An electronic component that performs signal processing and processing by connecting a propagation path of a surface acoustic wave is, for example, a non-linear element, but if it is formed on a circular path, it enables connection that is difficult on a two-dimensional plane. .

  This is a surface acoustic wave circuit system corresponding to an electronic circuit, and the connection region and the intersection region have a function corresponding to a switch in this case.

  That is, in this embodiment, a surface acoustic wave perturbation body formed in an intersection region or a connection region of a plurality of propagation paths has a function to transfer energy to and from a surface acoustic wave propagating through a plurality of propagation paths, and a switching function. Have.

< Second Reference Example >
FIG. 19 is a schematic diagram showing the structure of a spherical surface acoustic wave device according to a second reference example of the present invention.

This reference example is a modification of the fifth embodiment and uses a single interdigital electrode 130A to excite and detect a surface acoustic wave propagating through a plurality of propagation paths.

  The surface acoustic wave diffractor 140C2 reflects a surface acoustic wave that circulates the propagation path 120B after branching by reflecting a surface acoustic wave that propagates on the propagation path 120B by branching the surface acoustic wave that propagates on the propagation path 120A. It has a function of propagating on the propagation path 120A, and is specifically a ladder-type reflective electrode pattern.

  The branching of the surface acoustic wave can be controlled by changing the pattern shape of the surface acoustic wave diffractor 140C2. It can be actively controlled by changing the number of line elements of the pattern of the elastic surface diffractive body 140C2.

  The surface acoustic wave diffraction body 140C2 uses the same structure as the surface acoustic wave perturbation body 13 described above. In addition, a local heat distribution may be generated in a crossing region or a connection region to form a mass point having a discontinuous elastic property.

Since the structure of other components is the same as that of the fifth embodiment, the description thereof is omitted.

Next, the operation of the surface acoustic wave element according to this reference example will be described.

  First, the surface acoustic wave SAWr1 is excited by the interdigital electrode 130A.

  The excited surface acoustic wave SAWr1 goes around the propagation path 120A and reaches the surface acoustic wave diffractor 140C2.

  Here, the surface acoustic wave diffractor 140C2 splits the surface acoustic wave SAWr1 into a surface acoustic wave SAWr4 that propagates in the circular path 120A and a surface acoustic wave SAWr2 that propagates in the circular path 120C.

  The surface acoustic wave SAWr4 branched and propagating through the circulation path 120A reaches the interdigital electrode 130A and is detected.

  Further, the surface acoustic wave SAWr2 propagating through the circular path 120C propagates again as the surface acoustic wave SAWr3 through the surface acoustic wave diffractor 140C2, and reaches the interdigital electrode 130A and is detected.

As described above, according to the present reference example , a single interdigital electrode 140A is used to excite and detect a surface acoustic wave propagating through a plurality of propagation paths, and the surface acoustic wave is branched and propagated. It becomes possible to make it.

  In addition, since the propagation path is a circulation path around which the surface acoustic wave can circulate, it is possible to provide a surface acoustic wave element capable of branching and circulating the surface acoustic wave.

  Thereby, it is possible to detect the difference in the propagation state of the surface acoustic wave between the two propagation paths 120A and 120B (circular path) from the intensity, frequency response, and phase change of the detection signal from the interdigital electrode 130A. . That is, it is possible to configure an element that detects a change in the propagation state of the two propagation paths 120A and 120B.

  Further, if a sensitive film that changes the propagation speed of the surface acoustic wave according to the surrounding gas concentration is attached to one of the propagation paths 120A and 120B (both of the circulation paths), the surface acoustic wave of the two propagation paths 120A and 120B It is also possible to use it for a sensor using the phase change of the output based on the difference in propagation state.

  Furthermore, since the surface acoustic wave detection means and the surface acoustic wave excitation means are configured as the same interdigital electrode, a surface acoustic wave element having a simple structure can be provided.

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

It is a schematic diagram which shows the structure of the rotation angle measuring apparatus of the spherical surface acoustic wave element which concerns on the 1st reference example of this invention. It is sectional drawing which shows the deformation | transformation structure of the interdigital electrode in the embodiment. It is a schematic diagram for demonstrating the standing wave in the same embodiment. It is a schematic diagram for demonstrating the standing wave and the surface acoustic wave perturbation body in the embodiment. It is a schematic diagram for demonstrating the Rayleigh wave in the same embodiment. . It is a time chart for demonstrating the measurement procedure in the embodiment. It is a schematic diagram which shows the structure of the spherical surface acoustic wave element applied to the rotation angle measuring apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the modification of the spherical surface acoustic wave element applied to the rotation angle measuring apparatus in the embodiment. It is a schematic diagram which shows the structure of the surface acoustic wave perturbation body applied to the spherical surface acoustic wave element which concerns on the 2nd Embodiment of this invention. It is a top view which shows the structure of the surface acoustic wave perturbation body in the embodiment. It is a top view which shows the structure of the surface acoustic wave perturbation body applied to the spherical surface acoustic wave element which concerns on the 3rd Embodiment of this invention. It is a top view which shows the structure of the elastic surface perturbation body (composite type) in the embodiment. It is a schematic diagram for demonstrating the application example in the same embodiment. It is a schematic diagram which shows the structure of the rotation angle measuring apparatus of the spherical surface acoustic wave which concerns on the 4th Embodiment of this invention. It is a schematic diagram which shows the structure of the modification of the rotation angle measuring apparatus in the embodiment. It is a flowchart for demonstrating the procedure until the standing wave in the embodiment is generated. It is a schematic diagram which shows the structure of the surface acoustic wave element concerning the 5th Embodiment of this invention. It is a schematic diagram which shows the structure of the surface acoustic wave element which concerns on the 6th Embodiment of this invention. It is a schematic diagram which shows the structure of the surface acoustic wave element which concerns on the 2nd reference example of this invention. It is a schematic diagram showing a gyro using a conventional planar surface acoustic wave element. It is a schematic diagram which shows the structure of a general spherical surface acoustic wave element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,110 ... Spherical surface acoustic wave element, 11 ... Spherical member, 12, 12A, 12B ... Interdigital electrode for standing wave excitation, 13, 13x-13z, 140A-140D ... Surface acoustic wave perturbation body, 140C2 ... Surface acoustic wave diffractor, 13a ... Mass forming part, 13b ... Mass defect part, 14A, 14B, 14x1-14z2 ... Interdigital electrodes for detection, 20 ... High frequency signal source, 21A, 21B ... Signal intensity Measurement unit, 22 ... switching unit, 23 ... changeover switch, 120A to 120D propagation path, 130A to 130D ... interdigital electrode.

Claims (8)

A three-dimensional substrate having a propagation path composed of at least a part of a spherical surface capable of propagating surface acoustic waves;
According to the input drive signal, the surface of the propagation path has a surface acoustic wave wavelength equal to or less than 1/30 of the diameter of the sphere surface and a width equal to or less than 1/5 of the diameter of the sphere surface. Surface acoustic wave excitation means for exciting the first surface acoustic wave of the beam of
In accordance with the rotational movement of the three-dimensional substrate, the first surface acoustic wave is perturbed to a direction different from the propagation direction by the propagation path, and the surface acoustic wave has a diameter of 1/30 or less of the spherical surface. A surface acoustic wave perturbation means for exciting and propagating a second surface acoustic wave of a beam having a wavelength equal to or less than one fifth of the diameter of the sphere surface;
A surface acoustic wave detecting means for detecting the second surface acoustic wave excited and propagated in a different direction by the surface acoustic wave perturbation means and outputting a detection signal;
The propagation path is
It has an annular surface consisting of a continuous curved surface,
At least a part of the annular surface is provided with a circulation path for circulating the surface acoustic wave,
The surface acoustic wave excitation means is disposed in at least two circular paths that intersect each other ,
The surface acoustic wave perturbation means individually perturbs the first surface acoustic wave propagating through the circular path in accordance with the rotational movement of the three-dimensional substrate in three axial directions, and in a direction different from the circular path. At least one and a total of at least three are formed in each of the circumferential paths so as to individually excite and propagate the second surface acoustic wave;
The surface acoustic wave detecting means is arranged in each of three propagation paths so as to detect the second surface wave propagated by being excited by the plurality of surface acoustic wave perturbing means. A spherical surface acoustic wave element that propagates surface acoustic waves from one propagation path to another. The spherical surface acoustic wave device according to claim 1 ,
The three-dimensional substrate has a plurality of the propagation paths intersecting each other and a circulation path formed in each propagation path,
The surface acoustic wave detecting means is arranged on a circuit path different from a circuit path around which the excited second surface acoustic wave circulates. A spherical surface acoustic wave device that propagates waves. In the spherical surface acoustic wave device according to claim 1 or 2 ,
The surface acoustic wave excitation means excites a standing wave of the first surface acoustic wave along the circular path,
The surface acoustic wave perturbation means is periodically formed at a position where the amplitude of the standing wave is maximized in a partial region of the circulation path, and the position where the amplitude is minimized is the density and / or high A spherical surface acoustic wave element for propagating a surface acoustic wave from one propagation path to another propagation path, comprising a structure having a different thickness. In the spherical surface acoustic wave device according to claim 1 or 2 ,
The surface acoustic wave excitation means includes
Exciting a first surface acoustic wave that circulates in opposite directions around the surface of the three-dimensional substrate;
Having a function of generating a standing wave in at least a part of the circulation path by causing the first surface acoustic wave to circulate to interfere with each other;
The surface acoustic wave perturbation means is
In accordance with the rotational motion of the three-dimensional substrate, the surface acoustic wave constituting the standing wave is perturbed, and the second surface acoustic wave is excited and propagated in a direction different from the circulation direction. A spherical surface acoustic wave element for propagating a surface acoustic wave from one propagation path to another propagation path, wherein a structure having a different density and / or height is provided at the antinode of the standing wave. The spherical surface acoustic wave device according to any one of claims 1 to 4 ,
The surface acoustic wave excitation means includes
An interdigital electrode provided in contact with or in proximity to the surface of the three-dimensional substrate for applying an electric field of the drive signal;
Spherical elasticity for propagating surface acoustic waves from one propagation path to another propagation path, characterized by comprising a piezoelectric material for converting the electric field applied from this interdigital electrode into surface acoustic waves by the piezoelectric effect Surface wave device. The spherical surface acoustic wave device according to any one of claims 1 to 5 ,
The spherical surface acoustic wave element for propagating a surface acoustic wave from one propagation path to another propagation path, wherein the three-dimensional substrate is a piezoelectric crystal. The spherical surface acoustic wave device according to any one of claims 1 to 6 ,
The surface acoustic wave detection means includes
A piezoelectric material for converting the surface acoustic wave into an electric field by the piezoelectric effect;
A spherical surface acoustic wave element for propagating a surface acoustic wave from one propagation path to another propagation path, comprising interdigital electrodes for outputting a detection signal corresponding to the electric field. A rotation angle measuring device comprising the spherical surface acoustic wave element according to any one of claims 1 to 7,
Drive signal input means for inputting a high-frequency signal to the surface acoustic wave excitation means as the drive signal;
After the driving signal is input, the perturbation is applied to the surface acoustic wave according to the rotational motion of the three-dimensional substrate, and the rotation angle of the three-dimensional substrate is determined based on the detection signal output from the surface acoustic wave detecting means. A rotation angle measuring device comprising rotation angle measuring means for measuring.

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