JP2012085109A - Surface acoustic wave device - Google Patents
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Abstract
Description
本発明は、入力された電気信号を弾性表面波に変換し、この弾性表面波の圧電基板上における伝搬特性に基づく処理が施された後に電気信号に再び変換する弾性表面波デバイスに関する。 The present invention relates to a surface acoustic wave device that converts an input electrical signal into a surface acoustic wave, and converts the surface acoustic wave back into an electrical signal after processing based on propagation characteristics of the surface acoustic wave on a piezoelectric substrate.
弾性表面波センサ等の弾性表面波デバイスは、以下の好ましい特徴を有するために、これらの特徴を活かすことによる小型化、軽量化、無調整化が容易なデバイスとして多様なものが開発されつつある。 Since surface acoustic wave devices such as surface acoustic wave sensors have the following desirable characteristics, various devices are being developed that can be easily reduced in size, reduced in weight, and made non-adjustable by utilizing these characteristics. .
(1) 入力された電気信号が内部で変換されることによって得られる弾性表面波の波長が電磁波の波長の百万分の一程度と大幅に短い。
(2) 弾性表面波の伝搬路となる圧電基板上と、その圧電基板上に微細に形成可能な膜やパターンとして形成された電極等とから構成される。
(3) 圧電基板の表面の研磨は、弾性表面波の伝搬路が形成される片面だけで十分である。
(1) The wavelength of the surface acoustic wave obtained by internally converting the input electrical signal is significantly short, about one millionth of the wavelength of the electromagnetic wave.
(2) It is composed of a piezoelectric substrate serving as a surface acoustic wave propagation path, and a film, a pattern, and the like that can be finely formed on the piezoelectric substrate.
(3) For polishing the surface of the piezoelectric substrate, only one surface on which the propagation path of the surface acoustic wave is formed is sufficient.
(4) 弾性表面波の主要なエネルギーが圧電基板の表面に集中して伝搬するために、このような表面に形成された電極、あるいはその表面に接触する媒質との音響的な結合が密に、あるいは自在に達成される。
(5) 上記結合の下で弾性表面波に施される処理、あるいは生じる変化は、線形領域だけではなく非線形領域でも、安定に精度よく実現可能である。
(4) Since the main energy of the surface acoustic wave is concentrated and propagates on the surface of the piezoelectric substrate, the acoustic coupling between the electrode formed on such a surface or the medium in contact with the surface is tight. Or achieved at will.
(5) The process applied to the surface acoustic wave under the above-described coupling or the change that occurs can be realized stably and accurately not only in the linear region but also in the nonlinear region.
従来の弾性表面波センサとしては、例えば、後述する特許文献１に開示されるように以下の通りに構成された弾性表面波装置がある。
(1) 伝搬特性が同じである２つの伝搬路が圧電基板上に形成される。
As a conventional surface acoustic wave sensor, for example, there is a surface acoustic wave device configured as follows as disclosed in Patent Document 1 described later.
(1) Two propagation paths having the same propagation characteristics are formed on the piezoelectric substrate.
(2) これらの伝搬路の一方では、その伝搬路上に配置された遮断手段（該当する伝搬路上に塗布された樹脂、あるいは形成された溝）によって弾性表面波の伝搬が阻止されることによって、他方の伝搬路で生じるバルク波が予測される。
(3) 上記他方の伝搬路を伝搬した弾性波（弾性表面波およびバルク波を含む。）から上記予測されたバルク波が減じられることにより、バルク波の成分の抑圧が図られる。
(2) On one of these propagation paths, the propagation of the surface acoustic wave is blocked by the blocking means (resin applied on the propagation path or the groove formed) on the propagation path, A bulk wave generated in the other propagation path is predicted.
(3) The predicted bulk wave is subtracted from the elastic wave (including the surface acoustic wave and bulk wave) propagated through the other propagation path, thereby suppressing the bulk wave component.
このような構成の弾性表面波センサでは、バルク波に起因する精度や性能の低下が軽減される。 In the surface acoustic wave sensor having such a configuration, deterioration in accuracy and performance due to bulk waves is reduced.
なお、本発明に関連する先行技術としては、既述の特許文献１の他に後述する特許文献２がある。以下、これらの先行技術の概要を列記する。 In addition, as a prior art relevant to this invention, there exists patent document 2 mentioned later other than patent document 1 already stated. The outline of these prior arts is listed below.
(1) 「圧電性基板上に、弾性表面波を励振する入力電極と、該入力電極からの弾性表面波を電気信号に変換して出力する出力電極とを形成し、所望の周波数特性を得るために電極指交差幅に重み付けした弾性表面波装置において、前記入力電極は、前記弾性表面波の伝搬方向とほぼ直交する方向に互いに対向して配置され、且つ各々から弾性表面波と共に励振される前記圧電性基板の表面に対して平行に進行するバルク波を互いに逆相とするように構成された第１及び第２の入力電極を含み、該第１及び第２の入力電極の各々から前記出力電極へ伝搬する弾性表面波のいずれか一方を遮断する遮断手段を設けた」ことにより、「基板の特性によらず、主として圧電性基板に平行に進行する不要バルク波を抑圧して帯域外抑圧度を改善する」点に特徴がある弾性表面波装置…特許文献１ (1) “On the piezoelectric substrate, an input electrode for exciting a surface acoustic wave and an output electrode for converting the surface acoustic wave from the input electrode into an electric signal and outputting it are obtained to obtain a desired frequency characteristic. Therefore, in the surface acoustic wave device weighted to the electrode finger crossing width, the input electrodes are arranged to face each other in a direction substantially orthogonal to the propagation direction of the surface acoustic wave, and are excited together with the surface acoustic wave from each. First and second input electrodes configured so that bulk waves traveling parallel to the surface of the piezoelectric substrate are in opposite phases to each other, and from each of the first and second input electrodes By providing a blocking means to block any one of the surface acoustic waves propagating to the output electrode ”,“ outside of the band by suppressing unwanted bulk waves that travel mainly parallel to the piezoelectric substrate, regardless of the substrate characteristics. To improve the degree of suppression Characteristic surface acoustic wave device ... Patent Document 1
(2) 「弾性表面波素子の基板裏面を所定の条件を満たす角度に傾斜させる」ことにより、「この裏面で反射され基板表面に形成された出力電極または弾性表面波導波路の異なる位置に入射するバルク波による信号を相殺させ、高いＳＮ比で出力信号を取り出せるようにする」点に特徴がある…特許文献２ (2) By “inclining the back surface of the surface acoustic wave element to an angle satisfying a predetermined condition”, “incident at different positions of the output electrode or the surface acoustic wave waveguide reflected on the back surface and formed on the substrate surface It is characterized in that the signal due to the bulk wave is canceled and the output signal can be extracted with a high SN ratio.
ところで、上述した従来の弾性表面波センサでは、弾性表面波の伝搬の阻止や抑圧は、その弾性表面波の伝搬路に塗布された樹脂、あるいは形成された溝によって実現されていた。 By the way, in the conventional surface acoustic wave sensor described above, the propagation and suppression of the surface acoustic wave are realized by a resin applied to the propagation path of the surface acoustic wave or a groove formed.
また、このような樹脂の塗布や溝の形成は、弾性基板の表面に対する電極の形成とは別の工程として実現されるため、コスト高でとなるだけではなく、弾性表面波の伝搬を阻止する特性にバラツキが生じる要因となる可能性が高かった。 In addition, since the application of the resin and the formation of the groove are realized as a process different from the formation of the electrode on the surface of the elastic substrate, not only the cost is increased but also the propagation of the surface acoustic wave is prevented. There was a high possibility that this would cause variations in characteristics.
しかし、上記特性のバラツキについては、弾性表面波センサに対して要求される感度や性能のさらなる向上を妨げる要因となるために、解消や大幅な軽減を実現できる技術が強く要望されつつある。 However, since the variation in the above characteristics is a factor that hinders further improvement in sensitivity and performance required for the surface acoustic wave sensor, there is a strong demand for a technique that can be eliminated or greatly reduced.
本発明は、コストが大幅に増加することなく、性能が向上し、かつ特性のバラツキが安定に回避される弾性表面波デバイスを提供することを目的とする。 SUMMARY OF THE INVENTION An object of the present invention is to provide a surface acoustic wave device that improves performance and stably avoids variations in characteristics without significantly increasing costs.
請求項１に記載の発明では、圧電基板上に形成され、かつ電気信号を弾性波に変換する送波電極と、前記圧電基板を介して到来した弾性波を電気信号に変換する受波電極とを有する弾性表面波デバイスにおいて、伝搬速度調整体は、前記送波電極と前記受波電極とで挟まれた前記圧電基板上の領域に塗設あるいは形成され、前記弾性波の内、弾性表面波の伝搬速度をバルク波の伝搬速度に揃え、または前記弾性表面波と前記バルク波との伝搬速度の差を緩和する。 According to the first aspect of the present invention, a transmitting electrode that is formed on the piezoelectric substrate and converts an electric signal into an elastic wave, and a receiving electrode that converts the elastic wave that has arrived through the piezoelectric substrate into an electric signal; In the surface acoustic wave device, the propagation velocity adjusting body is coated or formed in a region on the piezoelectric substrate sandwiched between the transmitting electrode and the receiving electrode. Is made equal to the propagation velocity of the bulk wave, or the difference in propagation velocity between the surface acoustic wave and the bulk wave is relaxed.
すなわち、送波電極と受波電極とで挟まれた圧電基板上の領域と、その送波電極との間における弾性波の伝搬速度の差が圧縮されるため、このような伝搬速度の差に起因して生じるバルク波のレベルが低く抑えられ、あるいはバルク波の発生が回避される。 In other words, the difference in the propagation speed of the elastic wave between the area on the piezoelectric substrate sandwiched between the transmission electrode and the reception electrode and the transmission electrode is compressed. The level of the bulk wave generated due to this is suppressed low, or the generation of the bulk wave is avoided.
請求項２に記載の発明では、圧電基板上に形成され、かつ電気信号を弾性波に変換する送波電極と、前記圧電基板を介して到来した弾性波を電気信号に変換する受波電極とを有する弾性表面波デバイスにおいて、第一の擬似電極は、前記送波電極と前記受波電極とで挟まれた前記圧電基板上の領域の内、前記送波電極の近傍に形成され、前記送波電極と前記領域と間における前記弾性波の伝搬速度の差を緩和する。 According to a second aspect of the present invention, there is provided a transmitting electrode that is formed on a piezoelectric substrate and converts an electric signal into an elastic wave, and a receiving electrode that converts an elastic wave that has arrived through the piezoelectric substrate into an electric signal; The first pseudo electrode is formed in the vicinity of the transmitting electrode in a region on the piezoelectric substrate sandwiched between the transmitting electrode and the receiving electrode. A difference in propagation speed of the elastic wave between the wave electrode and the region is reduced.
すなわち、送波電極と伝搬路との継ぎ目でバルク波が発生する要因となる両者間の伝搬速度の差は、送波電極と同様に導体パターンとして一括して形成可能な擬似電極によって緩和される。 In other words, the difference in propagation velocity between the transmitting electrode and the propagation path that causes bulk waves to be generated is mitigated by the pseudo electrode that can be collectively formed as a conductor pattern, similar to the transmitting electrode. .
請求項３に記載の発明では、請求項２に記載の弾性表面波デバイスにおいて、第二の擬似電極は、前記領域の内、前記受波電極の近傍に形成され、前記領域と前記受波電極との間における前記弾性波の伝搬速度の差を緩和する。 According to a third aspect of the present invention, in the surface acoustic wave device according to the second aspect, the second pseudo electrode is formed in the vicinity of the receiving electrode in the region, and the region and the receiving electrode The difference in the propagation speed of the elastic wave between and is relaxed.
すなわち、伝搬路と受波電極との継ぎ目でバルク波が発生する要因となる両者間の伝搬速度の格差は、受波電極と同様に導体パターンとして一括して形成可能な擬似電極によって緩和される。 That is, the disparity in propagation velocity between the propagation path and the receiving electrode, which causes bulk waves to be generated, is alleviated by the pseudo electrode that can be formed as a conductor pattern at the same time as the receiving electrode. .
請求項４に記載の発明では、請求項２に記載の弾性表面波デバイスにおいて、前記第一の擬似電極は、前記第一の擬似電極に直接もしくは間接的に所定の媒質が接触する状態で、前記伝搬速度の差に起因するバルク波の発生が回避され、または許容される程度に前記差を緩和する。 According to a fourth aspect of the present invention, in the surface acoustic wave device according to the second aspect, the first pseudo electrode is in a state in which a predetermined medium is in contact with the first pseudo electrode directly or indirectly, Generation of bulk waves due to the difference in propagation speed is avoided or mitigated to an acceptable degree.
すなわち、第一の擬似電極よって上記伝搬速度の差が緩和される程度には、既述の媒質の種類、特性、量、位置等が加味される。 That is, the above-described medium type, characteristics, amount, position, and the like are added to the extent that the difference in the propagation speed is alleviated by the first pseudo electrode.
請求項５に記載の発明では、請求項３に記載の弾性表面波デバイスにおいて、前記第二の擬似電極は、前記第二の擬似電極に直接もしくは間接的に所定の媒質が接触する状態で、前記伝搬速度の差に起因するバルク波の発生が回避され、または許容される程度に前記差を緩和する。 According to a fifth aspect of the present invention, in the surface acoustic wave device according to the third aspect, the second pseudo electrode is in a state in which a predetermined medium is directly or indirectly in contact with the second pseudo electrode. Generation of bulk waves due to the difference in propagation speed is avoided or mitigated to an acceptable degree.
すなわち、第二の擬似電極よって上記伝搬速度の差が緩和される程度には、既述の媒質の種類、特性、量、位置等が加味される。 That is, the above-described medium type, characteristics, amount, position, and the like are added to the extent that the difference in the propagation speed is alleviated by the second pseudo electrode.
本発明によれば、従来例に比べて構成が大幅に変更されることなく、バルク波の発生に起因する性能および精度の低下が大幅に緩和され、あるいは回避される。
また、本発明に係る弾性表面波デバイスは、多様な媒質に対する柔軟な適応の下で所望の特性、性能および機能を実現可能となる。
したがって、本発明が適用された装置やシステムは、バルク波の発生のメカニズムに適合して安価にまたは容易に実現可能な構成により、弾性表面波デバイスに特有の利点が積極的に活用され、かつ多様な用途における所望の性能や信頼性が確度高く安定に実現される。
According to the present invention, the deterioration in performance and accuracy due to the generation of bulk waves is greatly eased or avoided without the configuration being significantly changed compared to the conventional example.
The surface acoustic wave device according to the present invention can realize desired characteristics, performance, and functions under flexible adaptation to various media.
Therefore, the apparatus and system to which the present invention is applied can positively utilize the advantages specific to the surface acoustic wave device by adopting a configuration that can be realized at low cost or easily by adapting to the mechanism of generation of bulk waves, and Desired performance and reliability in various applications can be realized with high accuracy and stability.
以下、図面に基づいて本発明の実施形態について詳細に説明する。
図１は、本発明の一実施形態を示す図である。
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of the present invention.
図において、圧電基板１１が有する矩形の片面の中央部には、その片面に相似な矩形の伝搬路１２が確保され、かつたんぱく質等の膜が形成される。このような伝搬路１２の特定の辺の近傍には、圧電基板１１上における導体のパターンとして櫛形電極(IDT:interdigital
transducer)１３Ｓが形成され、その特定の辺に対向する他の辺の近傍には、櫛形電極１３Ｒが上記櫛形電極１３Ｓに正対する状態で形成される。なお、このような櫛形電極１３Ｒの構成は既述の櫛形電極１３Ｓの構成と同じである。
In the figure, a rectangular propagation path 12 similar to one side is secured at the center of one side of the piezoelectric substrate 11 and a film of protein or the like is formed. In the vicinity of a specific side of the propagation path 12, a comb-shaped electrode (IDT: interdigital) is formed as a conductor pattern on the piezoelectric substrate 11.
transducer) 13S is formed, and in the vicinity of the other side opposite to the specific side, a comb-shaped electrode 13R is formed in a state of facing the comb-shaped electrode 13S. The configuration of the comb electrode 13R is the same as the configuration of the comb electrode 13S described above.
櫛形電極１３Ｓの一方の端子には信号源２０の出力が接続され、その櫛形電極１３Ｓの他方の端子および信号源２０の接地端子と共に接地される。 The output of the signal source 20 is connected to one terminal of the comb-shaped electrode 13S, and is grounded together with the other terminal of the comb-shaped electrode 13S and the ground terminal of the signal source 20.
櫛形電極１３Ｒの一方の端子は回路２１の入力に接続され、その櫛形電極１３Ｒの他方の端子と回路２１の接地端子とは、共に接地される。 One terminal of the comb-shaped electrode 13R is connected to the input of the circuit 21, and the other terminal of the comb-shaped electrode 13R and the ground terminal of the circuit 21 are both grounded.
以下、図１を参照して本実施形態の動作を説明する。
信号源２０は、例えば、上記伝搬路１２の中央部に該当する反応場に滴下され、あるいは接触する媒質について、計測されるべき項目に適した所定の周波数の交流信号を櫛形電極１３Ｓに与える。ここに、「媒質」とは、例えば、本実施形態に係る弾性表面波センサによって行われる計測や検査の対象として、反応場上に滴下され（滴下され得る）液体や溶液を意味する。
The operation of this embodiment will be described below with reference to FIG.
The signal source 20 applies, for example, an alternating current signal having a predetermined frequency suitable for an item to be measured to the comb-shaped electrode 13 </ b> S with respect to a medium dropped or contacted with a reaction field corresponding to the central portion of the propagation path 12. Here, the “medium” means, for example, a liquid or a solution that is dropped (can be dropped) on the reaction field as an object of measurement or inspection performed by the surface acoustic wave sensor according to the present embodiment.
櫛形電極１３Ｓは、このような交流信号によって励振され、図１に太い実線の矢印で示すように、伝搬路１２に弾性表面波を送出する。 The comb-shaped electrode 13S is excited by such an AC signal, and sends a surface acoustic wave to the propagation path 12 as indicated by a thick solid arrow in FIG.
この弾性表面波は、伝搬路１２上において既述の媒質が滴下されあるいは接触する反応場を伝搬して櫛形電極１３Ｒに到達し、その櫛形電極１３Ｒによって電気信号Ｅａに変換される。 This surface acoustic wave propagates through the reaction field where the above-mentioned medium is dropped or contacts on the propagation path 12 to reach the comb electrode 13R, and is converted into an electric signal Ea by the comb electrode 13R.
ところで、櫛形電極１３Ｓによって送出された弾性表面波のエネルギーの一部は、例えば、櫛形電極１３Ｓを形成する金属膜の部位と伝搬路１２との間における弾性波の伝搬速度の差（以下、「伝搬速度の格差」という。）が大きい場合には、図１に点線の矢印で示すように、圧電基板１１の表面ではなく内部を伝搬するバルク波に変換される。 By the way, a part of the energy of the surface acoustic wave transmitted by the comb-shaped electrode 13S is, for example, the difference in the propagation speed of the acoustic wave between the metal film portion forming the comb-shaped electrode 13S and the propagation path 12 (hereinafter referred to as “ In the case where the difference in propagation speed is large), it is converted into a bulk wave propagating not inside the surface of the piezoelectric substrate 11 but as indicated by a dotted arrow in FIG.
しかし、本実施形態では、伝搬路１２に塗設されたたんぱく質等の膜の厚さｔは、櫛形電極１３Ｓによって送出された表面弾性波の一部が既述の「伝搬速度の格差」に起因してバルク波に変換されない程度に、その伝搬路１２における弾性表面波の伝搬速度が遅くなる値に、予め設定される。 However, in the present embodiment, the thickness t of the protein film or the like applied to the propagation path 12 is caused by the above-described “propagation speed difference” due to a part of the surface acoustic wave transmitted by the comb-shaped electrode 13S. Thus, it is set in advance to a value at which the propagation speed of the surface acoustic wave in the propagation path 12 becomes slow to the extent that it is not converted into a bulk wave.
すなわち、本実施形態によれば、バルク波の発生が回避され、あるいは従来例に比べて、発生し得るバルク波のレベルが大幅に小さく抑えられる。
したがって、本発明によれば、バルク波に起因する精度や性能の低下が回避される。
That is, according to the present embodiment, the generation of bulk waves is avoided, or the level of bulk waves that can be generated is significantly reduced as compared with the conventional example.
Therefore, according to the present invention, deterioration in accuracy and performance due to bulk waves is avoided.
なお、本実施形態では、伝搬路１２の厚みｔは、例えば、反応場上にある（存在し得る）媒質の種類、量、分布等に適した値に予め設定されてもよい。 In the present embodiment, the thickness t of the propagation path 12 may be set in advance to a value suitable for the type, amount, distribution, etc., of the medium (that may exist) on the reaction field.
また、本実施形態では、伝搬路１２における弾性表面波の伝搬速度は、その伝搬路１２に塗布されたたんぱく質等の膜の厚みｔが調整されることにより、バルク波の発生が回避されあるいは緩和される値に設定されている。 In this embodiment, the propagation speed of the surface acoustic wave in the propagation path 12 is adjusted so that the generation of bulk waves is avoided or alleviated by adjusting the thickness t of the film of protein or the like applied to the propagation path 12. Is set to a value.
しかし、このような伝搬速度の設定は、例えば、以下の何れの形態で実現されてもよい。
(1) 伝搬路１２に塗設されたたんぱく質等の膜に関して、厚みｔに併せて（あるいは、厚みｔとは別に）、その厚みｔの物理的な分布と、該当する膜の形状、寸法、材質との全てまたは一部が好適に設定される。
However, such setting of the propagation speed may be realized in any of the following forms, for example.
(1) Concerning the film of protein or the like coated on the propagation path 12, in conjunction with the thickness t (or separately from the thickness t), the physical distribution of the thickness t, the shape, dimensions, and the like of the corresponding film, All or part of the material is suitably set.
(2) 伝搬路１２に塗設されたたんぱく質等の膜に併せて（あるいは、その膜とは別に）、図２に示すように、櫛形電極１３Ｓと伝搬路１２との間に、その伝搬路１２に引き渡される弾性表面波の伝搬速度を低く抑える擬似電極３１Ｓが形成される。 (2) Along with the film of protein or the like coated on the propagation path 12 (or separately from the film), the propagation path is disposed between the comb-shaped electrode 13S and the propagation path 12, as shown in FIG. The pseudo electrode 31 </ b> S is formed to suppress the propagation speed of the surface acoustic wave delivered to 12.
(3) 図２に破線で示すように、伝搬路１２と櫛形電極１３Ｒとの間に、その伝搬路１２から櫛形電極１３Ｒに引き渡される弾性表面波の伝搬速度を低く抑えることにより櫛形電極１３Ｒの近傍におけるバルク波の発生を抑制する擬似電極３１Ｒが備えられる。 (3) As indicated by broken lines in FIG. 2, the propagation speed of the surface acoustic wave delivered from the propagation path 12 to the comb electrode 13R is kept low between the propagation path 12 and the comb electrode 13R, thereby reducing the comb electrode 13R. A pseudo electrode 31R that suppresses the generation of bulk waves in the vicinity is provided.
(4) 既述の擬似電極３１Ｓ（３１Ｒ）によって伝搬速度が低く設定される程度は、例えば、その擬似電極３１Ｓ（３１Ｒ）に直接もしくは間接的に媒質が接触した（または接触し得る）状態で好適に設定される。 (4) The degree to which the propagation speed is set low by the above-described pseudo electrode 31S (31R) is, for example, in a state in which the medium is in contact with (or can be in contact with) the pseudo electrode 31S (31R). It is set suitably.
なお、上記擬似電極３１Ｓ、３１Ｒは、何れも、例えば、図２に示すようにラダー型の導体パターンとして構成可能であるが、このような導体パターンの形状、構造、寸法、配置等は、上記弾性表面波の伝搬速度を所望の形態で低く抑えることができるならば、如何なるものであってもよい。 Each of the pseudo electrodes 31S and 31R can be configured as a ladder-type conductor pattern as shown in FIG. 2, for example. The shape, structure, dimension, arrangement, and the like of such a conductor pattern are as described above. As long as the propagation speed of the surface acoustic wave can be kept low in a desired form, any surface wave may be used.
また、擬似電極３１Ｓ（３１Ｒ）に対する上記媒質の間接的な接触は、例えば、その媒質との物理的な隔たりを確保し、あるいは電気的な結合を粗とする「ダム」等を介して行われてもよい。 The indirect contact of the medium with the pseudo electrode 31S (31R) is performed, for example, through a “dam” or the like that secures a physical separation from the medium or roughs the electrical coupling. May be.
さらに、上記擬似電極３１Ｓ（３１Ｒ）を備えた構成では、これらの擬似電極３１Ｓ（３１Ｒ）は、伝搬路（反応場）上に塗設されたたんぱく質等とは異なり、櫛形電極１３Ｓ、１３Ｒと同様に弾性基板１１上にパターンとして一括して形成可能であり、配置、形状、寸法等の何れもが微細に設定可能であるため、低廉化に併せて、性能の安定な向上が図られる。 Further, in the configuration provided with the pseudo electrodes 31S (31R), these pseudo electrodes 31S (31R) are different from the proteins and the like coated on the propagation path (reaction field), and are similar to the comb electrodes 13S and 13R. In addition, since it can be collectively formed as a pattern on the elastic substrate 11 and any of the arrangement, shape, dimensions and the like can be set finely, the performance can be stably improved along with the reduction in cost.
また、本発明は、本実施形態のような弾性表面波センサに限定されず、例えば、弾性表面波フィルタ、弾性表面波発振器、弾性表面波共振器、弾性表面波導波路、弾性表面波遅延器、弾性表面波相関器等の多様な弾性表面波デバイスにも同様に適用可能である。 Further, the present invention is not limited to the surface acoustic wave sensor as in the present embodiment. For example, the surface acoustic wave filter, the surface acoustic wave oscillator, the surface acoustic wave resonator, the surface acoustic wave waveguide, the surface acoustic wave delay device, The present invention can be similarly applied to various surface acoustic wave devices such as a surface acoustic wave correlator.
さらに、本発明は、上述した実施形態に限定されず、本発明の範囲において多様な実施形態の構成が可能であり、構成要素の全てまたは一部に如何なる改良が施されてもよい。 Further, the present invention is not limited to the above-described embodiments, and various configurations can be made within the scope of the present invention, and any improvement may be applied to all or some of the components.
１１ 圧電基板
１２ 伝搬路
１３Ｒ，１３Ｓ 櫛形電極
２０ 信号源
２１ 回路
３１Ｒ，３１Ｓ 擬似電極
11 Piezoelectric substrate 12 Propagation path 13R, 13S Comb electrode 20 Signal source 21 Circuit 31R, 31S Pseudo electrode
Claims (5)
前記送波電極と前記受波電極とで挟まれた前記圧電基板上の領域に塗設あるいは形成され、前記弾性波の内、弾性表面波の伝搬速度をバルク波の伝搬速度に揃え、または前記弾性表面波と前記バルク波との伝搬速度の差を緩和する伝搬速度調整体を備えた
ことを特徴とする弾性表面波デバイス。 A surface acoustic wave device formed on a piezoelectric substrate and having a transmitting electrode for converting an electric signal into an elastic wave and a receiving electrode for converting an elastic wave that has arrived through the piezoelectric substrate into an electric signal. ,
Coated or formed in a region on the piezoelectric substrate sandwiched between the transmitting electrode and the receiving electrode, and among the elastic waves, the propagation speed of the surface acoustic wave is aligned with the propagation speed of the bulk wave, or A surface acoustic wave device comprising: a propagation velocity adjusting body that relaxes a difference in propagation velocity between a surface acoustic wave and the bulk wave.
前記送波電極と前記受波電極とで挟まれた前記圧電基板上の領域の内、前記送波電極の近傍に形成され、前記送波電極と前記領域と間における前記弾性波の伝搬速度の差を緩和する第一の擬似電極を備えた
ことを特徴とする弾性表面波デバイス。 A surface acoustic wave device formed on a piezoelectric substrate and having a transmitting electrode for converting an electric signal into an elastic wave and a receiving electrode for converting an elastic wave that has arrived through the piezoelectric substrate into an electric signal. ,
Of the region on the piezoelectric substrate sandwiched between the transmitting electrode and the receiving electrode, formed in the vicinity of the transmitting electrode, the propagation speed of the elastic wave between the transmitting electrode and the region A surface acoustic wave device comprising a first pseudo electrode for reducing the difference.
前記領域の内、前記受波電極の近傍に形成され、前記領域と前記受波電極との間における前記弾性波の伝搬速度の差を緩和する第二の擬似電極を備えた
ことを特徴とする弾性表面波デバイス。 The surface acoustic wave device according to claim 2,
A second pseudo electrode that is formed in the vicinity of the receiving electrode in the region and relaxes a difference in propagation speed of the elastic wave between the region and the receiving electrode is provided. Surface acoustic wave device.
前記第一の擬似電極は、
前記第一の擬似電極に直接もしくは間接的に所定の媒質が接触する状態で、前記伝搬速度の差に起因するバルク波の発生が回避され、または許容される程度に前記差を緩和する
ことを特徴とする弾性表面波デバイス。 The surface acoustic wave device according to claim 2,
The first pseudo electrode is
In a state where a predetermined medium is in direct or indirect contact with the first pseudo electrode, generation of a bulk wave due to the difference in the propagation speed is avoided, or the difference is reduced to an allowable level. A surface acoustic wave device.
前記第二の擬似電極は、
前記第二の擬似電極に直接もしくは間接的に所定の媒質が接触する状態で、前記伝搬速度の差に起因するバルク波の発生が回避され、または許容される程度に前記差を緩和する
ことを特徴とする弾性表面波デバイス。 The surface acoustic wave device according to claim 3,
The second pseudo electrode is
In a state where a predetermined medium is in direct or indirect contact with the second pseudo electrode, generation of a bulk wave due to the difference in propagation velocity is avoided, or the difference is reduced to an allowable level. A surface acoustic wave device.
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| JPS5535887B2 (en) * | 1975-04-01 | 1980-09-17 | ||
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