JP3343442B2 - Surface acoustic wave converter - Google Patents
Surface acoustic wave converterInfo
- Publication number
- JP3343442B2 JP3343442B2 JP13756494A JP13756494A JP3343442B2 JP 3343442 B2 JP3343442 B2 JP 3343442B2 JP 13756494 A JP13756494 A JP 13756494A JP 13756494 A JP13756494 A JP 13756494A JP 3343442 B2 JP3343442 B2 JP 3343442B2
- Authority
- JP
- Japan
- Prior art keywords
- sound absorbing
- surface acoustic
- acoustic wave
- absorbing portion
- wave converter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Description
【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【0001】[0001]
【産業上の利用分野】本発明は、電気信号を一旦弾性表
面波に変換するとともに同弾性表面波を再度電気信号に
変換して出力することにより、入力した電気信号の特性
を変更して出力する弾性表面波変換器に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of converting an electric signal into a surface acoustic wave, converting the same into an electric signal again, and outputting the electric signal. To a surface acoustic wave converter.
【0002】[0002]
【従来の技術】従来、この種の弾性表面波変換器は、例
えば特開平6−29771号公報に示されているよう
に、櫛歯状にそれぞれ形成した入力電極及び出力電極を
相対向させてなる圧電基板上に、入力電極及び出力電極
の各外側にて吸音材をそれぞれ塗布してなる第1及び第
2吸音部と、入力電極の外側の角部にて複数の帯状の吸
音材を同入力電極の各櫛歯部に対して斜めに交差させて
塗布してなる第3吸音部とを備え、多重反射や回折現象
による不要弾性表面波が発生しないようにして周波数に
対する群遅延特性及び振幅特性が良好になるようにして
いる。2. Description of the Related Art Conventionally, this type of surface acoustic wave converter has a structure in which an input electrode and an output electrode formed in a comb shape are opposed to each other as shown in, for example, Japanese Patent Application Laid-Open No. 6-29771. A first and a second sound absorbing portion formed by applying a sound absorbing material on each of the outer sides of the input electrode and the output electrode on the piezoelectric substrate, and a plurality of band-shaped sound absorbing materials on the outer corners of the input electrode. A third sound absorbing portion coated obliquely with respect to each comb tooth portion of the input electrode, and a group delay characteristic and an amplitude with respect to frequency so that unnecessary surface acoustic waves due to multiple reflections and diffraction phenomena are not generated. The characteristics are made good.
【0003】[0003]
【発明が解決しようとする課題】しかし、上記従来の装
置にあっても、第1及び第2吸音部の各内側境界、圧電
基板の端部及び第3吸音部の境界での反射による不要弾
性表面波が発生して、周波数に対する群遅延特性及び振
幅特性が充分に良好にならない。本発明は上記問題に対
処するためになされたもので、前記反射による不要弾性
表面波を抑制して、周波数に対する群遅延特性および振
幅特性がより良好となる弾性表面波変換器を提供するこ
とにある。However, even in the above-mentioned conventional device, unnecessary elasticity due to reflection at the inner boundaries of the first and second sound absorbing portions, the ends of the piezoelectric substrate, and the boundaries of the third sound absorbing portions. A surface wave is generated, and the group delay characteristic and the amplitude characteristic with respect to the frequency are not sufficiently improved. The present invention has been made in order to address the above-described problem, and it is an object of the present invention to provide a surface acoustic wave converter that suppresses unnecessary surface acoustic waves due to the reflection, and has better group delay characteristics and amplitude characteristics with respect to frequency. is there.
【0004】[0004]
【課題を解決するための手段】上記目的を達成するため
に、本発明の構成上の特徴は、櫛歯状にそれぞれ形成し
た入力電極及び出力電極を相対向させてなる圧電基板上
に、入力電極及び出力電極の各外側にて吸音材をそれぞ
れ塗布してなる第1及び第2吸音部と、入力電極の外側
の角部にて複数の帯状の吸音材を同入力電極の各櫛歯部
に対して斜めに交差させて塗布してなる第3吸音部とを
有する弾性表面波変換器において、圧電基板上の入力電
極と第1吸音部の間及び第3吸音部上にて同第1及び第
3吸音部を構成する吸音材よりも軟質の吸音材を塗布し
てなる第4吸音部と、圧電基板上の出力電極と第2吸音
部の間にて同第2吸音部を構成する吸音材よりも軟質の
吸音材を塗布してなる第5吸音部とを設けたことにあ
る。In order to achieve the above object, a structural feature of the present invention is that an input electrode and an output electrode formed in a comb shape are opposed to each other on a piezoelectric substrate. First and second sound absorbing portions each formed by applying a sound absorbing material on the outside of each of the electrodes and the output electrode, and a plurality of band-shaped sound absorbing materials on each of the outer corners of the input electrode; A surface acoustic wave converter having a third sound absorbing portion coated obliquely with respect to the first sound absorbing portion, between the input electrode on the piezoelectric substrate and the first sound absorbing portion and on the third sound absorbing portion. And a fourth sound absorbing portion coated with a softer sound absorbing material than the sound absorbing material constituting the third sound absorbing portion, and the second sound absorbing portion between the output electrode on the piezoelectric substrate and the second sound absorbing portion. A fifth sound absorbing portion formed by applying a softer sound absorbing material than the sound absorbing material is provided.
【0005】[0005]
【発明の作用・効果】上記のように構成した本発明にお
いては、入力電極と第1吸音部の間に位置する第4吸音
部も、出力電極と第2吸音部の間に位置する第5吸音部
も軟質に構成されているので、同第4及び第5吸音部の
各電極側の境界での反射による不要弾性表面波が減少す
る。また、軟質の第4吸音部は第3吸音部を覆っている
ので、第3吸音部の境界での反射による不要弾性表面波
も減少する。さらに、圧電基板の端部側に位置する第1
及び第2吸音部は硬質に構成されるので、圧電基板の端
部に届く弾性表面が減少して、同端部での反射による不
要弾性表面波が減少する。このようにして不要弾性表面
波の発生が抑制される結果、本発明の弾性表面波変換器
によれば、周波数に対する群遅延特性および振幅特性が
より良好となる。In the present invention configured as described above, the fourth sound absorbing portion located between the input electrode and the first sound absorbing portion is also the fifth sound absorbing portion located between the output electrode and the second sound absorbing portion. Since the sound absorbing portion is also soft, unnecessary surface acoustic waves due to reflection at the boundaries of the fourth and fifth sound absorbing portions on the electrode side are reduced. Further, since the soft fourth sound absorbing portion covers the third sound absorbing portion, unnecessary surface acoustic waves due to reflection at the boundary of the third sound absorbing portion are also reduced. Furthermore, the first substrate located on the end side of the piezoelectric substrate
In addition, since the second sound absorbing portion is configured to be hard, the amount of elastic surface reaching the end of the piezoelectric substrate is reduced, and unnecessary surface acoustic waves due to reflection at the end are reduced. As a result of suppressing the generation of the unnecessary surface acoustic wave in this way, according to the surface acoustic wave converter of the present invention, the group delay characteristic and the amplitude characteristic with respect to the frequency are further improved.
【0006】[0006]
【実施例】以下、本発明の一実施例を図面を用いて説明
すると、図1は同実施例に係る弾性表面波変換器を概略
的に示した平面図である。この弾性表面波変換器は、Li
NbO3,LiTaO3,水晶などの圧電材料を直方体状に形成した
圧電基板10を備えている。圧電基板10上には、櫛歯
状にそれぞれ形成した入力電極11及び出力電極12が
相対向して設けられていて、弾性表面波が入力電極11
から出力電極12に伝搬されるようになっている。入力
電極11は平行に延設された一対の基部11a,11b
と各基部11a,11bからそれぞれ垂直に延設された
多数の櫛歯部11c,11dとからなり、各櫛歯部11
c,11d間の交差長を異ならせて重み付け弾性表面波
変換器を構成している。出力電極12は平行に延設され
た一対の基部12a,12bと各基部12a,12bか
らそれぞれ垂直に延設された少数の櫛歯部12c,12
dとからなり、各櫛歯部12c,12d間の交差長を一
定にして正規型弾性表面波変換器を構成している。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view schematically showing a surface acoustic wave converter according to an embodiment of the present invention. This surface acoustic wave converter uses Li
There is provided a piezoelectric substrate 10 in which a piezoelectric material such as NbO 3 , LiTaO 3 , quartz or the like is formed in a rectangular parallelepiped shape. An input electrode 11 and an output electrode 12 formed in a comb shape are provided on the piezoelectric substrate 10 so as to face each other.
To the output electrode 12. The input electrode 11 is a pair of bases 11a and 11b extending in parallel.
And a number of comb teeth 11c, 11d vertically extending from the bases 11a, 11b, respectively.
A weighted surface acoustic wave converter is configured by making the intersection length between c and 11d different. The output electrode 12 includes a pair of bases 12a and 12b extending in parallel and a small number of comb teeth 12c and 12 extending vertically from the bases 12a and 12b, respectively.
d to form a normal surface acoustic wave converter with the intersecting length between the comb portions 12c and 12d constant.
【0007】入力電極11及び出力電極12の各外側に
は硬質の吸音材(例えばJIS−Aの60)を塗布した
吸音部13,14がそれぞれ設けられている。入力電極
11の外側の角部であって櫛歯部11c,11dが交差
していない部分には、複数の帯状に形成した硬質の吸音
材(例えばJIS−Aの60)を各櫛歯部11c,11
dに斜めに交差するように塗布した吸音部15が設けら
れている。この吸音部15の各帯の一端はまとめて吸音
部13に接続され、各他端は入力電極11の基部11
a,11bに分離して接続されている。また、入力電極
11と出力電極12との間の弾性表面波の伝搬路上であ
ってその縁部には硬質の吸音材(例えばJIS−Aの6
0)を塗布した一対の吸音部16,16が設けられてい
る。On the outside of each of the input electrode 11 and the output electrode 12, there are provided sound absorbing portions 13 and 14 to which a hard sound absorbing material (for example, JIS-A 60) is applied. A plurality of band-shaped hard sound absorbing materials (for example, JIS-A 60) are provided at the outer corners of the input electrode 11 where the comb teeth 11c and 11d do not intersect. , 11
A sound absorbing portion 15 is provided so as to diagonally cross d. One end of each band of the sound absorbing unit 15 is connected to the sound absorbing unit 13 at a time, and the other end is connected to the base 11 of the input electrode 11.
a and 11b. A hard sound absorbing material (for example, JIS-A 6) is provided on the surface acoustic wave propagation path between the input electrode 11 and the output electrode 12 and at the edge thereof.
A pair of sound absorbing parts 16, 16 coated with 0) are provided.
【0008】さらに、入力電極11と吸音部13の間に
位置する圧電基板10の上、入力電極11の外側の角部
であって櫛歯部11c,11dの一部を含む吸音部15
の上、基部11a,11bの一部であって吸音部15が
接続されている部分の上、及び同部分の側方に位置する
圧電基板10の上には、前記吸音部13〜16を構成す
る吸音材よりも軟質の吸音材(例えば、JIS−Aの2
4)を塗布した吸音部17が設けられている。この吸音
部17の形成にあたっては、図2に示すように吸音部1
3,15を形成した後に、軟質の吸音材を圧電基板10
上に塗布することによって吸音部17を形成する。ま
た、出力電極12と吸音部14の間に位置する圧電基板
10の上には、前記吸音部17と同等な軟質の吸音材
(例えば、JIS−Aの24)を塗布した吸音部18が
設けられている。Further, on the piezoelectric substrate 10 located between the input electrode 11 and the sound absorbing portion 13, a sound absorbing portion 15 which is a corner portion outside the input electrode 11 and includes a part of the comb teeth portions 11c and 11d.
The sound absorbing parts 13 to 16 are formed on a part of the base parts 11 a and 11 b to which the sound absorbing part 15 is connected and on the piezoelectric substrate 10 located on the side of the part. Sound absorbing material that is softer than the sound absorbing material (for example, JIS-A 2
The sound absorbing part 17 coated with 4) is provided. In forming the sound absorbing portion 17, as shown in FIG.
After forming the layers 3 and 15, the soft sound absorbing material is
The sound absorbing part 17 is formed by applying the composition on the top. On the piezoelectric substrate 10 located between the output electrode 12 and the sound absorbing part 14, a sound absorbing part 18 coated with a soft sound absorbing material (for example, JIS-A 24) equivalent to the sound absorbing part 17 is provided. Have been.
【0009】このように構成した弾性表面波変換器の使
用状態においては、入力電極11の基部11a,11b
に高周波発振器21が接続されるとともに出力電極12
の基部12a,12b間には抵抗22が接続されて、抵
抗22の両端から出力信号を得るようにする。これによ
り、高周波発振器21からの高周波電気信号は入力電極
11にて弾性表面波に変換され、同弾性表面波が出力電
極12に伝搬されて同電極12にてふたたび電気信号に
変換されて出力される。この場合、入力された高周波信
号は、入力電極11、出力電極12などにより、帯域制
限されかつ所定の周波数特性をもつ信号に変換されて出
力されることになる。When the surface acoustic wave converter thus configured is in use, the bases 11a and 11b of the input electrode 11 are used.
High-frequency oscillator 21 is connected to output electrode 12
A resistor 22 is connected between the bases 12a and 12b so that an output signal is obtained from both ends of the resistor 22. Thereby, the high-frequency electric signal from the high-frequency oscillator 21 is converted into a surface acoustic wave at the input electrode 11, and the surface acoustic wave is transmitted to the output electrode 12, converted again into an electric signal at the same electrode 12, and output. You. In this case, the input high-frequency signal is converted into a signal having a band-limited and predetermined frequency characteristic by the input electrode 11, the output electrode 12, and the like, and is output.
【0010】このような弾性表面波変換器の作動状態に
おいては、吸音部13〜18は圧電基板10上を伝搬す
る不要弾性表面波を吸収する。具体的には、吸音部1
3,14は硬質に構成されていて、圧電基板10上を同
基板10の端部に向かって伝搬する弾性表面波を多量に
吸収して同端部に到達する弾性表面波を減少させるの
で、同端部での反射による不要弾性表面波を減少させ
る。吸音部15は入力電極11の櫛歯部11c,11d
での多重反射による不要弾性表面波を吸収する。吸音部
16は回折現象による圧電基板10上の不要弾性表面波
を吸収する。吸音部17,18は軟質に構成されている
ので、吸音部17の一部であって入力電極11と吸音部
13との間に位置する部分及び吸音部18は吸音部1
7,18に入射する際の同吸音部17,18の境界での
反射による不要弾性表面波の発生を抑制するとともに、
同吸音部17,18から吸音部13,14に入射する際
の同吸音部13,14の境界での反射による不要弾性表
面波の発生を抑制する。さらに、吸音部17の一部であ
って吸音部15を覆っている部分は、吸音部15の境界
での反射による不要弾性表面波の発生を抑制する。In such an operation state of the surface acoustic wave converter, the sound absorbing portions 13 to 18 absorb unnecessary surface acoustic waves propagating on the piezoelectric substrate 10. Specifically, the sound absorbing unit 1
3 and 14 are configured to be hard and absorb a large amount of surface acoustic waves propagating on the piezoelectric substrate 10 toward the edge of the substrate 10 to reduce the surface acoustic waves reaching the edge. An unnecessary surface acoustic wave due to reflection at the same end is reduced. The sound absorbing part 15 is a comb tooth part 11c, 11d of the input electrode 11.
Unnecessary surface acoustic waves due to multiple reflections are absorbed. The sound absorbing section 16 absorbs unnecessary surface acoustic waves on the piezoelectric substrate 10 due to a diffraction phenomenon. Since the sound absorbing portions 17 and 18 are configured to be soft, a portion of the sound absorbing portion 17 that is located between the input electrode 11 and the sound absorbing portion 13 and the sound absorbing portion 18 are formed of the sound absorbing portion 1.
In addition to suppressing the generation of unnecessary surface acoustic waves due to reflection at the boundary between the sound absorbing parts 17 and 18 when the light enters the sound absorbing parts 7 and 18,
The generation of unnecessary surface acoustic waves due to reflection at the boundary between the sound absorbing portions 13 and 14 when the light enters the sound absorbing portions 13 and 14 from the sound absorbing portions 17 and 18 is suppressed. Further, a part of the sound absorbing portion 17 that covers the sound absorbing portion 15 suppresses generation of unnecessary surface acoustic waves due to reflection at the boundary of the sound absorbing portion 15.
【0011】次に、吸音部17,18による不要弾性表
面波の発生の抑制効果を確認するための実験結果につい
て説明する。図3(A)及び図4(A)は吸音部13〜16
のみを設けた従来の弾性表面波変換器の周波数に対する
群遅延特性及び振幅特性をそれぞれ表すグラフであり、
図3(B)及び図4(B)は前記弾性表面波変換器に吸音部
17,18を付加した場合の周波数に対する群遅延特性
及び振幅特性をそれぞれ表すグラフである。図3(A)及
び図3(B)を比較することにより、吸音部17,18を
設けた本実施例によれば、大きな周期をもつリップル、
うねりが小さくなったことが確認される。また、図4
(A)及び図4(B)を比較することにより、吸音部17,
18を設けた本実施例によれば、振幅特性の立ち上がり
及び立ち下がり特性が良好すなわち傾きが若干急峻にな
ったことが確認される。Next, experimental results for confirming the effect of suppressing the generation of unnecessary surface acoustic waves by the sound absorbing portions 17 and 18 will be described. FIGS. 3A and 4A show the sound absorbing portions 13 to 16.
It is a graph respectively showing the group delay characteristics and the amplitude characteristics with respect to the frequency of the conventional surface acoustic wave converter provided only,
FIGS. 3B and 4B are graphs respectively showing the group delay characteristic and the amplitude characteristic with respect to the frequency when the sound absorbing units 17 and 18 are added to the surface acoustic wave converter. By comparing FIG. 3A and FIG. 3B, according to the present embodiment in which the sound absorbing portions 17 and 18 are provided, the ripple having a large period can be obtained.
It is confirmed that the swell has been reduced. FIG.
By comparing FIG. 4A and FIG.
According to the present embodiment provided with 18, it is confirmed that the rising and falling characteristics of the amplitude characteristic are good, that is, the slope is slightly steep.
【0012】以上の説明から理解できるとおり、上記実
施例によれば、吸音部17,18を設けたことにより、
圧電基板10上における不要弾性表面波が良好に抑制さ
れて、弾性表面波変換器の周波数に対する群遅延特性及
び振幅特性が改善される。As can be understood from the above description, according to the above embodiment, the provision of the sound absorbing portions 17 and 18 allows
Unnecessary surface acoustic waves on the piezoelectric substrate 10 are satisfactorily suppressed, and the group delay characteristics and the amplitude characteristics with respect to the frequency of the surface acoustic wave converter are improved.
【図1】 本発明の一実施例を示す弾性表面波変換器の
平面概略図である。FIG. 1 is a schematic plan view of a surface acoustic wave converter according to an embodiment of the present invention.
【図2】 前記弾性表面波変換器の吸音部17,18を
設ける前の状態を示す部分図である。FIG. 2 is a partial view showing a state before the sound absorbing portions 17 and 18 of the surface acoustic wave converter are provided.
【図3】 (A)は従来の弾性表面波変換器の周波数に対
する群遅延特性を示すグラフであり、(B)は前記実施例
に係る弾性表面波変換器の同群遅延特性を示すグラフで
ある。3A is a graph showing a group delay characteristic with respect to the frequency of the conventional surface acoustic wave converter, and FIG. 3B is a graph showing the same group delay characteristic of the surface acoustic wave converter according to the embodiment. is there.
【図4】 (A)は従来の弾性表面波変換器の周波数に対
する振幅特性を示すグラフであり、(B)は前記実施例に
係る弾性表面波変換器の同振幅特性を示すグラフであ
る。FIG. 4A is a graph showing amplitude characteristics with respect to frequency of a conventional surface acoustic wave converter, and FIG. 4B is a graph showing the same amplitude characteristics of the surface acoustic wave converter according to the embodiment.
10…圧電基板、11…入力電極、12…出力電極、1
3〜18…吸音部。10: piezoelectric substrate, 11: input electrode, 12: output electrode, 1
3 to 18: sound absorbing parts.
Claims (1)
出力電極を相対向させてなる圧電基板上に、前記入力電
極及び出力電極の各外側にて吸音材をそれぞれ塗布して
なる第1及び第2吸音部と、前記入力電極の外側の角部
にて複数の帯状の吸音材を同入力電極の各櫛歯部に対し
て斜めに交差させて塗布してなる第3吸音部とを有する
弾性表面波変換器において、前記圧電基板上の入力電極
と第1吸音部の間及び前記第3吸音部上にて同第1及び
第3吸音部を構成する吸音材よりも軟質の吸音材を塗布
してなる第4吸音部と、前記圧電基板上の出力電極と第
2吸音部の間にて同第2吸音部を構成する吸音材よりも
軟質の吸音材を塗布してなる第5吸音部とを設けたこと
を特徴とする弾性表面波変換器。1. A first and a second sound absorbing material which are respectively applied to the outside of each of the input electrode and the output electrode on a piezoelectric substrate having input and output electrodes formed in a comb shape facing each other. A second sound-absorbing portion, and a third sound-absorbing portion formed by applying a plurality of band-shaped sound absorbing materials obliquely to each of the comb teeth of the input electrode at corners outside the input electrode. In the surface acoustic wave converter, a sound absorbing material softer than the sound absorbing materials constituting the first and third sound absorbing portions between the input electrode on the piezoelectric substrate and the first sound absorbing portion and on the third sound absorbing portion. A fourth sound absorbing portion formed by coating, and a fifth sound absorbing member formed by applying a softer sound absorbing material between the output electrode on the piezoelectric substrate and the second sound absorbing portion than the sound absorbing material constituting the second sound absorbing portion. And a surface acoustic wave converter.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13756494A JP3343442B2 (en) | 1994-06-20 | 1994-06-20 | Surface acoustic wave converter |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13756494A JP3343442B2 (en) | 1994-06-20 | 1994-06-20 | Surface acoustic wave converter |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH088687A JPH088687A (en) | 1996-01-12 |
JP3343442B2 true JP3343442B2 (en) | 2002-11-11 |
Family
ID=15201672
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP13756494A Expired - Fee Related JP3343442B2 (en) | 1994-06-20 | 1994-06-20 | Surface acoustic wave converter |
Country Status (1)
Country | Link |
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JP (1) | JP3343442B2 (en) |
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1994
- 1994-06-20 JP JP13756494A patent/JP3343442B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
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JPH088687A (en) | 1996-01-12 |
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