JPS63266913A - Surface acoustic wave device - Google Patents
Surface acoustic wave deviceInfo
- Publication number
- JPS63266913A JPS63266913A JP10057287A JP10057287A JPS63266913A JP S63266913 A JPS63266913 A JP S63266913A JP 10057287 A JP10057287 A JP 10057287A JP 10057287 A JP10057287 A JP 10057287A JP S63266913 A JPS63266913 A JP S63266913A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- comb
- acoustic wave
- surface acoustic
- spurious
- 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.)
- Pending
Links
- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 27
- 239000011358 absorbing material Substances 0.000 claims description 21
- 239000000758 substrate Substances 0.000 abstract description 10
- 230000003247 decreasing effect Effects 0.000 abstract description 3
- 230000005855 radiation Effects 0.000 abstract 1
- 239000000126 substance Substances 0.000 abstract 1
- 230000000737 periodic effect Effects 0.000 description 9
- 238000005452 bending Methods 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229920006332 epoxy adhesive Polymers 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【発明の詳細な説明】
（発明の技術分野）
本発明は、くしば状電極を備える弾性表面波装置に関す
る。DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a surface acoustic wave device including comb-shaped electrodes.
（発明の技術的背景とその問題点）
この種の弾性表面波装置はフィルタや遅延線等として利
用されいるが、特に画像伝送装置の中継器においてフィ
ルタとして用いられる場合には多段で使用されるため、
各段で発生する伝送歪みが順次加算され１画像劣化の原
因となってしまう。(Technical background of the invention and its problems) This type of surface acoustic wave device is used as a filter, delay line, etc., but especially when used as a filter in a repeater of an image transmission device, it is used in multiple stages. For,
Transmission distortions occurring at each stage are added up sequentially, causing deterioration of one image.
従って、画像伝送装置用のフィルタとして用いられる弾
性表面波装置としては帯域内のスプリアスの棚幅、群遅
延が０ 、１ ｄ Ｂ （ｐｅａｋ ｔｏ ｐｅｑｋ）
以下、±２〜３ＢＳｅｃを満たす特性が要求される。Therefore, as a surface acoustic wave device used as a filter for an image transmission device, the shelf width of the spurious in the band and the group delay are 0 and 1 dB (peak to peqk).
Below, characteristics satisfying ±2 to 3 BSec are required.
第６図には弾性表面波装置の一例が示されており、基板
ｌ上には傾斜電極構造の７ボタイズド型くしば状電極２
が設けられている。このくしば状電極２は複数の電極指
２ａとこれら電極指に共通に接続されている共通電極２
ｂとを有し、一方の共通電極２ｂには信号源４が接続さ
れている。また、基板ｌ上にはこのくしば状電極２に対
向して正規型くしば状電極３が設けられている。このく
しば状電極３は電極指３ａと電極指３ａに共通に接続さ
れている共通電極３ｂとを有し、一方の共通電極３ｂに
負荷５が接続されている。An example of a surface acoustic wave device is shown in FIG.
is provided. This comb-shaped electrode 2 includes a plurality of electrode fingers 2a and a common electrode 2 commonly connected to these electrode fingers.
b, and a signal source 4 is connected to one common electrode 2b. Further, a regular comb-shaped electrode 3 is provided on the substrate l, facing the comb-shaped electrode 2. This comb-shaped electrode 3 has electrode fingers 3a and a common electrode 3b commonly connected to the electrode fingers 3a, and a load 5 is connected to one common electrode 3b.
ところで、上記アポタイズド型くしば状電極２において
、正規型くしば状電極３から離間して音響中心Ａより右
側に位置する電極指２ａ群の領域＆＋ 、ａ２に含まれ
る非交差部は、表面波の伝搬部としては不要である。そ
こで、領域ａ２に吸音材を塗布してスプリアスの低域を
図ることが行われている。この場合吸音材の領域ａ２へ
の塗布状態にばらつきを有すると、各弾性表面波装置に
おいて大きさの異なったスプリアスが発生するので、吸
音材は領域ａ２に高精度で塗布する必要がある。しかし
、弾性表面波装置を１００ＭＨｚ以りの高周波帯域でフ
ィルタとして用いる場合には上記くしば状電極２が２ｍ
ｍ口程度に形成されるため、吸音材を上記望城ａ２に０
．１ｍｍ以上の高精度で塗布せざるを得す、従って、量
産化が不可能である。また、領域ａ２で電極指２ａが破
断することもあるので歩留りも低下してしまう。By the way, in the above-mentioned apotized comb-like electrode 2, the non-intersecting part included in the area &+ and a2 of the electrode finger group 2a located on the right side of the acoustic center A and away from the regular comb-like electrode 3 is a surface wave. It is unnecessary as a propagation part. Therefore, a sound absorbing material is applied to the area a2 to reduce the low frequency of the spurious noise. In this case, if there are variations in the application state of the sound absorbing material to the region a2, spurious waves of different magnitudes will occur in each surface acoustic wave device, so the sound absorbing material needs to be applied to the region a2 with high precision. However, when the surface acoustic wave device is used as a filter in a high frequency band of 100 MHz or higher, the comb-shaped electrode 2 has a length of 2 m.
Since it is formed with a diameter of about m, the sound absorbing material is placed on
．． Coating must be performed with a high precision of 1 mm or more, which makes mass production impossible. Further, since the electrode fingers 2a may break in the region a2, the yield will also decrease.
第７図には他の従来の弾性表面波装置が示されている。FIG. 7 shows another conventional surface acoustic wave device.
即ち、この弾性表面波装置は１２８゜Ｙ−Ｘニオブ酸リ
チウム等の圧電物質から成る基板１上に傾斜電極構造の
７ポタイズド型くしば状電極２が設けられ、このくしば
状電極２は傾斜して交差している複数の電極指２ａと、
これら電極指２ａに共通に接続されている共通電極２ｂ
、２Ｃを有している。一方の共通電極２ｃには信号源４
が接続され、厚さが約２００ＯＡのアルミニウム膜から
成る導電膜６が一体的に形成されている。この導電膜６
は音響中心Ａより図中で右側に位置する電極指２ａ群の
非交差部を覆っている。That is, in this surface acoustic wave device, a 7-potized comb-shaped electrode 2 having an inclined electrode structure is provided on a substrate 1 made of a piezoelectric material such as 128° Y-X lithium niobate. A plurality of electrode fingers 2a intersecting each other,
A common electrode 2b commonly connected to these electrode fingers 2a
, 2C. A signal source 4 is connected to one common electrode 2c.
are connected to each other, and a conductive film 6 made of an aluminum film having a thickness of about 200 OA is integrally formed. This conductive film 6
covers the non-intersecting portion of the group of electrode fingers 2a located on the right side of the acoustic center A in the figure.
このくしば状電極２には約Ｉｎｍの間隔を保持して正規
型くしば状電極３が対向している。このくしば状電極３
は均一に交差している電極指３ａと、これら電極指３ａ
に共通に接続されている共通電極３ｂ、３ｂとを有し、
一方の共通電極３ｂは負荷５を介して接地されている０
両くしば状電極２．３の近傍には吸音材７が配されてい
る。これら吸音材７はエポキシ系の接着剤より成り、基
板ｌ端部等での表面波の不要な反射を除去し、バルク波
の不要な励振を防止する。尚、図中、８はダミー電極で
ある。A regular comb-shaped electrode 3 faces the comb-shaped electrode 2 with an interval of about Inm. This comb-shaped electrode 3
are electrode fingers 3a that are uniformly crossed, and these electrode fingers 3a.
having common electrodes 3b, 3b commonly connected to
One common electrode 3b is grounded via a load 5.
A sound absorbing material 7 is arranged near the comb-like electrodes 2.3. These sound absorbing materials 7 are made of epoxy adhesive, and eliminate unnecessary reflections of surface waves at the ends of the substrate l, etc., and prevent unnecessary excitation of bulk waves. In addition, in the figure, 8 is a dummy electrode.
以上の構成を有する弾性表面波装置の周波数特性を測定
したところ、第８図（Ａ）に示す結果が得られた。即ち
、この第８図（Ａ）は相対利得の振幅周波数特性を示し
、通過帯域領域Ａには周期的なスプリアスが発生してい
た。このスプリアスは第８図（Ｂ）に示すように、約０
．３ｄＢ（ｐｅａｋ ｔｏ ｐｅａｋ）の大きさで発生
しており、大きい周期ｆ１のスプリアスと小さい周期ｆ
２のスプリアスとが合成されてものであった。そして、
ｆｌ及びｆ２周期の各スプリアスの周期数間隔はｆ＋＝
２ｆｚの関係にあることが判明した。また、ｆ１周期の
スプリアスに対応する表面波は主信号に対してくしば状
電極２の１／２の長さ寸法を伝搬するのに要する時間と
等しい時間差で伝搬するのが判明した。When the frequency characteristics of the surface acoustic wave device having the above configuration were measured, the results shown in FIG. 8(A) were obtained. That is, FIG. 8(A) shows the amplitude frequency characteristic of the relative gain, and periodic spurious signals were generated in the passband region A. This spurious is approximately 0 as shown in Figure 8 (B).
．． It occurs at a magnitude of 3 dB (peak to peak), and has a large period f1 spurious and a small period f1.
It was a combination of the second spurious and the second spurious. and,
The period number interval of each spurious in fl and f2 periods is f+=
It turned out that there is a 2fz relationship. It has also been found that the surface wave corresponding to the f1 period spurious propagates with a time difference equal to the time required to propagate half the length of the comb-like electrode 2 with respect to the main signal.
基板ｌの底面を凹凸を設けて荒しても上記ｆ＋ 、ｆｚ
同周期スプリアスは僅かに減少するだけであった。従っ
て、ｆｌ 、ｆｚ同周期スプリアスは直接バルク波によ
って生じるのではなく、又これらスプリアスは底面の凹
凸によりバルク波の一部が散乱されて減少していること
が判る。Even if the bottom surface of the substrate l is roughened by providing unevenness, the above f+, fz
The same-period spurious was only slightly reduced. Therefore, it can be seen that the same-period spurious waves of fl and fz are not directly caused by the bulk waves, and that these spurious waves are reduced by a portion of the bulk waves being scattered by the unevenness of the bottom surface.
尚、第６図に示すと同様な構造の他の弾性表面波装置に
おいて、傾斜電極構造の７ポタイズド型くしば状電極に
おける表面波の伝搬方向と平行な長さ寸法を中心周波数
で定まる波長により測定し、周波数特性を調べたところ
、同様に上記した周期的なスプリアスが発生していた。In addition, as shown in FIG. 6, in another surface acoustic wave device with a similar structure, the length dimension parallel to the propagation direction of the surface wave in the 7-potized comb-shaped electrode with the inclined electrode structure is determined by the wavelength determined by the center frequency. When we measured and examined the frequency characteristics, we found that the above-mentioned periodic spurious was also occurring.
ところで、第７図に示す弾性表面波装置の表面波の発生
態様は第９図のように示すことができる。即ち、傾斜電
極構造のアポタイズド型くしば状電極２において、音響
中心Ａからは主応答となる表面波Ｗｏが発生し、正規型
くしば状電極３（第７図参照）と対向する端部の′電極
指２ａからは表面波Ｗ１が発生し、正規型くしば状電極
３より離間する端部の電極指２ａ及び共通電極の端面か
らは表面波Ｗ２が発生する。また、音響中心Ａより発生
して逆方向に伝搬する表面波は端部の電極指２ａにて反
射され、表面波Ｗ３として伝搬する。そして、くしば状
電極２の音響中心Ａから両端までの長さ寸法を文、基板
１での表面波の伝搬速度をＶとした場合、各表面波Ｗｏ
”Ｗ３が正規型くしば状電極３に到達する時間差は主
応答の表面波Ｗｏを基準にすると、表面波Ｗ１はｉ／Ｖ
秒の進み、表面波Ｗ２は１７１秒の遅れ、表面波Ｗ３は
２ ｉ／Ｖ秒の遅れとなる。従って、ｆｚ同周期スプリ
アスは表面波Ｗ３により発生していると考えられる。By the way, the manner in which surface waves are generated in the surface acoustic wave device shown in FIG. 7 can be shown as shown in FIG. 9. That is, in the apotized comb-shaped electrode 2 with the inclined electrode structure, the surface wave Wo, which is the main response, is generated from the acoustic center A, and the surface wave Wo, which is the main response, is generated at the end facing the regular comb-shaped electrode 3 (see FIG. 7). 'Surface waves W1 are generated from the electrode fingers 2a, and surface waves W2 are generated from the electrode fingers 2a at the ends separated from the regular comb-shaped electrode 3 and the end face of the common electrode. Further, a surface wave generated from the acoustic center A and propagating in the opposite direction is reflected by the electrode finger 2a at the end and propagates as a surface wave W3. If the length from the acoustic center A of the comb-shaped electrode 2 to both ends is V, and the propagation speed of the surface wave on the substrate 1 is V, then each surface wave Wo
``The time difference when W3 reaches the regular comb-shaped electrode 3 is based on the main response surface wave Wo, and the surface wave W1 is i/V.
As the seconds advance, the surface wave W2 is delayed by 171 seconds, and the surface wave W3 is delayed by 2 i/V seconds. Therefore, it is considered that the fz same period spurious is generated by the surface wave W3.
そこで、本発明者は上記反射による表面波Ｗ３がｆ２周
期のスプリアスであることを確認すべく、第１θ図に示
すように、共通電極２Ｃ及び導電膜６の一部を表面波の
波長入のｌ／４だけ段状に削り取り、周期数特性を測定
した。この結果。Therefore, in order to confirm that the surface wave W3 caused by the reflection is a spurious wave with a frequency of f2, the inventors set a part of the common electrode 2C and a part of the conductive film 6 at the wavelength of the surface wave, as shown in FIG. 1θ. It was removed stepwise by 1/4, and the periodicity characteristics were measured. As a result.
ｆ２周期のスプリアスは約０ 、１ ｄＢ（ｐｅａｋ
ｔ。The f2 period spurious is approximately 0,1 dB (peak
t.
ｐｅａｋ）まで減少した。この場合非切削部ｂ＋ で反
射される表面波Ｗ３と切削部ｂ２で反射される表面波Ｗ
３ ′とば入／４の切削寸法差があることから理論的に
はπの位相差が生じ、正規型くしば状電極３にて受波さ
れた時点で相互に打ち消し合うはずである。しかし、実
際には上記したようにｆ２周期のスプリアスが生じる。peak). In this case, the surface wave W3 reflected at the non-cutting part b+ and the surface wave W reflected at the cutting part b2
Theoretically, since there is a cutting dimension difference of 3' and burr/4, a phase difference of π occurs, and when the waves are received by the regular comb-shaped electrode 3, they should cancel each other out. However, in reality, as described above, spurious signals of f2 period occur.
この原因は表面波Ｗ３とＷ３ ′の導電膜６を通過する
長さ寸法がす７部とｂ２部とでは異なるため、これら表
面波に位相差が生じることによると考えられる。The reason for this is thought to be that the lengths of the surface waves W3 and W3' passing through the conductive film 6 are different between the portions 7 and 2, and therefore a phase difference occurs between these surface waves.
一方、ｆ１周期のスプリアスは約０．２５ｄＢ（ｐｅａ
ｋ ｔｏ ｐｅａｋ）と僅かに減少するだけであった。On the other hand, the f1 period spurious is approximately 0.25 dB (pea
k to peak).
これは表面波Ｗ２とＷ２’が入／４の位相差を有し、か
つ導電膜６を通過する長さ寸法がす３部とｂ２部で同様
に異なっているためである。This is because the surface waves W2 and W2' have a phase difference of 0/4, and the lengths of the waves passing through the conductive film 6 are similarly different between the 3 part and the b2 part.
本発明者は更に第１１図に示すように１表面波の伝搬方
向に対して直交する方向を基準にして、角度０で共通電
極２Ｃ及び導電ｌ１５Ｉ６を斜めに切削した。そして、
周波数特性を測定したところ、切削角度Ｏが大きくなる
に従って１記スプリアスの振幅が小さくなり、特にｆ２
周期のスプリアスが第１２図に示すように、大きく減少
した。即ち、ｆ２周期のスプリアスはほぼ消滅していた
０以上の結果より、反射による表面波Ｗ３がｆ２の周期
のスプリアスを発生させていることが判明した。The inventor further cut the common electrode 2C and the conductive l15I6 obliquely at an angle of 0 with respect to a direction perpendicular to the propagation direction of one surface wave, as shown in FIG. and,
When the frequency characteristics were measured, it was found that as the cutting angle O increases, the amplitude of the first spurious becomes smaller, especially f2
As shown in FIG. 12, the periodic spurious was greatly reduced. That is, from the result of 0 or more in which the spurious with the f2 period almost disappeared, it was found that the surface wave W3 due to reflection generates the spurious with the f2 period.
尚、ｆ１周期のスプリアスも約０．２ｄＢに減少してい
た。Incidentally, the f1 period spurious was also reduced to about 0.2 dB.
（発明の目的）
本発明の目的は、周期スプリアスの極めて小さい弾性表
面波装置を提供することにある。(Object of the Invention) An object of the present invention is to provide a surface acoustic wave device with extremely small periodic spurious.
（発明の概要）
本発明は、電極指を交差させたアポタイズド型くしば状
電極において、共通電極の他のくしば状電極より離間す
る部分を電極指の非交差部の長さ寸法を徐々に小さくす
る方向に屈折させ、この屈折部に表面波の伝搬方向に対
して角度を有する傾斜端縁を設けたことを特徴とする。(Summary of the Invention) The present invention provides an apotized comb-like electrode in which electrode fingers are crossed, and the length of the non-intersecting part of the common electrode is gradually adjusted to It is characterized in that it is bent in the direction of making it smaller, and that this bending part is provided with an inclined edge that is at an angle with respect to the propagation direction of the surface wave.
（発明の実施例）
以下１本発明の実施例を図面を参照して詳細に説明する
。(Embodiments of the Invention) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.
本発明に係る弾性表面波装置は第１図に示すように、基
板２０を備えている。この基板２０は１２８°Ｘ−Ｙニ
オブ酸リチウム等の圧電性物質から形成され、傾斜電極
構造の７ポタイズド型くしば状電極２１が設けられてい
る、このくしば状電極２１は傾斜して交差している複数
の電極指２１ａと、これら電極指に共通に接続されてい
る共通電極２１ｂ、２２とを有している。一方の共通電
極２１ｂは接地され、他、方の共通電極２２には信号源
４が接続され、又これら共通電極２１ｂ、２２には電極
指２１ａと交差しないダミー電極１５が設けられている
。このくしば状電極２１には約１ｍｍの間隔を保持して
正規型くしば状電極２３が対向している。このくしば状
電極２３は均一に交差している電極指２３ａと、これら
電極指２３ａに共通に接続されている共通電極２３ｂ、
２３ｃとから成り、一方の共通電極２３ｂは接地され、
他方の共通型Ｊｉｉ ２３ ｃは負荷５を介して接地さ
れている。The surface acoustic wave device according to the present invention includes a substrate 20, as shown in FIG. The substrate 20 is made of a piezoelectric material such as 128° It has a plurality of electrode fingers 21a and common electrodes 21b and 22 commonly connected to these electrode fingers. One common electrode 21b is grounded, the other common electrode 22 is connected to the signal source 4, and these common electrodes 21b and 22 are provided with a dummy electrode 15 that does not intersect with the electrode finger 21a. A regular comb-shaped electrode 23 faces the comb-shaped electrode 21 with an interval of approximately 1 mm. This comb-shaped electrode 23 includes electrode fingers 23a that are uniformly crossed, a common electrode 23b that is commonly connected to these electrode fingers 23a,
23c, one common electrode 23b is grounded,
The other common type Jii 23 c is grounded via a load 5.
傾斜電極構造の７ボタイズド型くしば状電極２ｌにおい
て、共通電極２２の正規型くしば状電極２３より離間す
る部分は、音響中心Ａ＆Ｉ！より電極指２１ａの非交差
部の長さ寸法を徐々に小さくする方向に屈折し、屈折部
２２Ａを形成している。この屈折部２２Ａは外端側に主
応答の表面波の伝搬方向（矢印参照）に対して所定角度
で傾斜している傾斜端縁２２ａを有している。そして、
この屈折部２２Ａ上には傾斜端縁２２ａを含んだ状態で
エポキシ系の接着剤より成る吸音材２５が設けられてい
る。この吸音材２５は略コ字状に形成され、共通電極２
２の非屈折部と他の共通電極２１ｂの各縁部を含む吸音
部２６．２７を有している。尚、＜シば状電極２３の近
傍にも同材質から成る吸音材２８が設けられている。In the 7-bottomized comb-shaped electrode 2l having an inclined electrode structure, the portion of the common electrode 22 that is spaced apart from the regular comb-shaped electrode 23 is located at the acoustic center A&I! The electrode finger 21a is bent in a direction that gradually reduces the length of the non-intersecting portion, thereby forming a bent portion 22A. The refracting portion 22A has an inclined edge 22a on the outer end side, which is inclined at a predetermined angle with respect to the propagation direction (see arrow) of the main response surface wave. and,
A sound absorbing material 25 made of epoxy adhesive is provided on the bent portion 22A, including the inclined edge 22a. This sound absorbing material 25 is formed in a substantially U-shape, and the common electrode 25
2 and each edge of the other common electrode 21b. Note that a sound absorbing material 28 made of the same material is also provided near the wrinkled electrode 23.
以上の構成を有する本発明の弾性表面波装置において、
音響中心Ａより発生して共通電極２２の屈折部２２Ａ側
に伝搬する表面波Ｗ３は、第２図に示すように、吸音材
２５の中央部に吸音され、かつその一部は傾斜端縁２２
ａに反射されて吸音部２７及び２６に順次吸音される。In the surface acoustic wave device of the present invention having the above configuration,
As shown in FIG. 2, the surface wave W3 generated from the acoustic center A and propagating toward the bending portion 22A of the common electrode 22 is absorbed by the central portion of the sound absorbing material 25, and a portion of it is absorbed by the inclined edge 22.
The sound is reflected by the sound absorbing portions 27 and 26 and is successively absorbed by the sound absorbing portions 27 and 26.
そして、周波数特性を測定したところ、ｆ２周期のスプ
リアスは殆ど消滅しており、表面波Ｗ３が正規型くしば
状電極２３側で受波されていないことが判明した。Then, when the frequency characteristics were measured, it was found that the spurious wave with the f2 period had almost disappeared, and that the surface wave W3 was not received on the regular comb-shaped electrode 23 side.
また、傾斜端縁２２ａで発生して吸音材２５の中央部に
て吸音されなかった表面波Ｗ２は、第２図に示すように
、該端縁２２ａと直交する方向に伝搬し、その殆どが吸
音部２７にて吸音される。Furthermore, the surface waves W2 generated at the inclined edge 22a and not absorbed at the center of the sound absorbing material 25 propagate in a direction perpendicular to the edge 22a, as shown in FIG. The sound is absorbed by the sound absorbing section 27.
そして、周波数特性を測定した結果、ｆ＋同周期スプリ
アスは約０ 、１ ｄ Ｂ （ｐｅａｋ ｔｏ ｐｅａ
ｋ）に低減していた。Then, as a result of measuring the frequency characteristics, f + same-period spurious is approximately 0,1 dB (peak to pea
k).
上記実施例において、正規型くしば状電極２３の共通電
極２３ｂを負荷５側に接続し、他方の共通電極２３ｃを
接地すると、ｆｚ同周期スプリアスは同様に殆ど消滅し
、又ｆ１周期のスプリアスは更に減少し、約０ 、０５
ｄ Ｂ （ｐｅａｋ ｔｏ ｐｅａｋ）になった。In the above embodiment, when the common electrode 23b of the regular comb-like electrode 23 is connected to the load 5 side and the other common electrode 23c is grounded, the fz same-period spurious almost disappears, and the f1-period spurious also disappears. It further decreases to about 0.05
It became d B (peak to peak).
ところで、第１図に示す弾性表面波装置において、傾斜
電極構造の７ポタイズド型くしば状電極２１の両端に位
置して信号源４に接続されている電極指１５’及び電極
指２１ａ′からは周期的。By the way, in the surface acoustic wave device shown in FIG. 1, from the electrode finger 15' and the electrode finger 21a' which are located at both ends of the 7-potized comb-shaped electrode 21 with the inclined electrode structure and are connected to the signal source 4, Periodic.
かつ瞬時に印加される電界が突然打ち切られることに起
因して表面波Ｗｌ 、Ｗ！ ’が発生する。これらの表
面波Ｗｌ 、 Ｗｚ ’は主応答の表面波に対して同一
の時間差で進み、又遅れているのでスプリアスの振幅特
性には同相で加わる。さて、第３図に示すように、くし
ば状電極２１における電極指２１ａの交差部の中心近傍
に仮想的に直線りを設け、この直線りの主応答の表面波
の伝搬方向に対する傾斜角をΦとすると、この傾斜角Φ
が大きくなるに従って、つまり、電極指１５’と電極指
２１ａ’の長さ寸法が小さくなるに従ってｆ＋同周期ス
プリアスが減少した。そして、電極指１５′の長さ寸法
を１１％その対向している内端の電極指２１ａの長さ寸
法をｌｘとすると、電極指１５′の長さを１１＋ｌｚの
約１０％の長さ寸法に設定した場合ｆ１周期のスプリア
スが０．１ｄＢ（ｐ＠ａｋ ｔｏ ｐｅａｋ）以下に低
減することが判った。尚、電極指２１ａ′の長さ寸法は
傾斜角Φとは無関係に屈折部２２Ａの傾きを電極指２１
ａ′が小さくなるように設計することで電極指１５’よ
りも短く設定することができるのは勿論である。Moreover, due to the abrupt termination of the instantaneously applied electric field, surface waves Wl, W! ' occurs. Since these surface waves Wl and Wz' advance with the same time difference and lag behind the main response surface wave, they are added to the spurious amplitude characteristics in the same phase. Now, as shown in FIG. 3, a virtual straight line is provided near the center of the intersection of the electrode fingers 21a in the comb-shaped electrode 21, and the inclination angle of this straight line with respect to the propagation direction of the surface wave of the main response is determined. If Φ, then this inclination angle Φ
The f+ same-period spurious response decreased as the length of the electrode finger 15' and the electrode finger 21a' became smaller. If the length of the electrode finger 15' is 11% and the length of the opposing inner end electrode finger 21a is lx, then the length of the electrode finger 15' is approximately 10% of 11+lz. It has been found that when set to , the f1 period spurious is reduced to 0.1 dB (p@ak to peak) or less. Incidentally, the length dimension of the electrode finger 21a' is determined based on the inclination of the bent portion 22A regardless of the inclination angle Φ.
Of course, by designing so that a' is small, it can be set shorter than the electrode finger 15'.
また、上記７ポタイズド型くしば状電極２１において、
共通電極２２の非屈折部と他の共通電極２１ｂとの各外
端縁では、第２図に示すように、ｗ２ 、ｗ３等の波の
一部が反射されるので、反射波Ｗ４ 、Ｗｓが発生する
。しかるに、共通電極２２の非屈折部と他の共通電極２
１ｂの各端縁はそれぞれ吸音部２６．２７にて覆われて
いるので、Ｌ記反射波Ｗ４ 、Ｗｓはこれら吸音部２６
．２７により吸音される。従って、これら反射波Ｗ４、
Ｗｓによるスプリアスの増大を確実に防止することがで
きる。In addition, in the 7-potized comb-shaped electrode 21,
As shown in FIG. 2, at each outer edge of the non-refracting portion of the common electrode 22 and the other common electrode 21b, some of the waves w2, w3, etc. are reflected, so the reflected waves W4, Ws Occur. However, the non-bending portion of the common electrode 22 and the other common electrode 2
Since each end edge of 1b is covered with a sound absorbing part 26, 27, the L reflected waves W4 and Ws are caused by these sound absorbing parts 26.
．． 27 absorbs the sound. Therefore, these reflected waves W4,
It is possible to reliably prevent an increase in spurious signals due to Ws.
モして、吸音材２５の中央部にて屈折部２２Ａの一部を
含み、かつその吸音部２６．２７にて共通電極２２の非
屈折部と他の共通電極２１ｂの端縁を含むように吸音材
を塗布する場合には、塗布精度がそれほど要求されない
ので、歩留まりよく弾性表面波装置を量産化することが
可能である。The central part of the sound absorbing material 25 includes a part of the bending part 22A, and the sound absorbing part 26.27 includes the non-bending part of the common electrode 22 and the edge of the other common electrode 21b. When applying the sound absorbing material, since high application accuracy is not required, surface acoustic wave devices can be mass-produced with high yield.
第４図には本発明の他の実施例が示されている。即ち、
この実施例の傾斜構造の７ポタイズド型くしば状電極２
１において、共通電極３２の屈折部３２Ａは外方に突出
する傾斜端縁３２ａを有している。そして、この屈折部
３２Ａ上には傾斜端縁３２ａを含んだ状態で吸音材２９
が設けられている。この吸音材２９は２字状に形成され
ている。この実施例において、表面波Ｗ３は傾斜端縁２
２ａにて反射されて吸音材２９に吸音され、又傾斜端縁
２２ａを含む外端縁で発生する表面波Ｗ２も同様に吸音
材２９に吸音される。従って、ｆ２周期のスプリアスを
消滅させ、かつｆ＋同周期スプリアスを低減することが
できる上に、表面波Ｗ２ 、Ｗ３を吸音するために２字
状の吸音材２９を設ければよいので量産化の点で優れて
いる。Another embodiment of the invention is shown in FIG. That is,
7-potized comb-shaped electrode 2 with a tilted structure in this example
In No. 1, the bent portion 32A of the common electrode 32 has an inclined edge 32a projecting outward. The sound absorbing material 29 is placed on the bending portion 32A, including the inclined edge 32a.
is provided. This sound absorbing material 29 is formed in a two-character shape. In this example, the surface wave W3 is generated by the inclined edge 2.
2a and is absorbed by the sound absorbing material 29, and the surface wave W2 generated at the outer edge including the inclined edge 22a is also absorbed by the sound absorbing material 29. Therefore, it is possible to eliminate the f2-period spurious and reduce the f+ periodic spurious, and since it is only necessary to provide the double-shaped sound absorbing material 29 to absorb the surface waves W2 and W3, mass production is facilitated. Excellent in that respect.
第５図には更に本発明の他の実施例が示されている。即
ち、この実施例では第１図に示す傾斜電極構造の７ボタ
イズド型くしば状電極２１．２１’が対向して配され、
一方のくしば状電極２１は送波用として用いられ、他方
のくしば状電極２１′は受波用として用いられている。FIG. 5 shows yet another embodiment of the invention. That is, in this embodiment, the seven-bottomed comb-shaped electrodes 21 and 21' having the inclined electrode structure shown in FIG. 1 are arranged to face each other,
One comb-shaped electrode 21 is used for transmitting waves, and the other comb-shaped electrode 21' is used for receiving waves.
そして、両くしば状電極２１．２１’はマルチストリッ
プカプラ３０にて結合されている０本実施例においても
同一の効果が得られるのは勿論である。Of course, the same effect can be obtained even in the embodiment in which both the comb-like electrodes 21 and 21' are connected by the multi-strip coupler 30.
上記各実施例では傾斜電極構造の７ボタイズド型くしば
状電極に本発明を適用しているが１通常のアポタイズド
型くしば状電極にも本発明を適用することができ、この
場合にはｆ１周期のスプリアスは約１７２に低減し、又
ｆ２周期のスプリアスは殆ど消滅する。In each of the above embodiments, the present invention is applied to a 7-bottomed comb-like electrode with an inclined electrode structure, but the present invention can also be applied to a normal apotized-type comb-like electrode, and in this case, f1 The period spurious is reduced to about 172, and the f2 period spurious almost disappears.
また、共通電極２２の屈折部２２Ａにおける傾斜端縁２
２ａは各種の形状に設定することができ、要は表面波Ｗ
２ 、Ｗ３を吸音材側に案内する形状であればよい。Further, the inclined edge 2 at the bent portion 22A of the common electrode 22
2a can be set in various shapes, and the point is that the surface wave W
2. Any shape may be used as long as it guides W3 toward the sound absorbing material.
（発明の効果）
本発明によれば、電極指を交差させたアポタイズト型電
極において、共通電極の他のくしば状電極より離間する
部分を電極指の非交差部の長さ寸法を徐々に小さくする
方向に屈折させ、該屈折部に表面波の伝搬方向に対して
角度を有する傾斜端縁を設けたことで、周期的なスプリ
アスを大幅に低減することができる。従って、画像の伝
送歪みを充分に抑圧する必要のある画像伝送デバイスや
広帯域特性の優れたフィルタ等として好適な弾性表面波
装置を提供することができる。(Effects of the Invention) According to the present invention, in an apotized electrode in which electrode fingers are crossed, the length of the non-intersecting part of the common electrode is gradually reduced in the part of the common electrode that is spaced apart from other comb-shaped electrodes. By refracting the beam in the direction of the surface wave and providing the refracting portion with an inclined edge having an angle with respect to the propagation direction of the surface wave, periodic spurious waves can be significantly reduced. Therefore, it is possible to provide a surface acoustic wave device suitable for use as an image transmission device that needs to sufficiently suppress image transmission distortion, a filter with excellent broadband characteristics, and the like.
第１図及び第２図は本発明に係る弾性表面波装置の平面
図とその動作を説明する概略平面図、第３図は第１図の
装置の要部を電極指等の長さと周期スプリアスとの関係
で示す平面図、第４図は本発明の他の実施例に係る装置
の平面図、第５図は本発明の更に他の実施例に係る装置
の概略平面図、第６図及び第７図は傾斜電極構造の７ポ
タイズド型くしば状電極を備える従来の弾性表面波装置
をそれぞれ示す平面図、第８図は（Ａ）、（Ｂ）は第７
図に示す装置の振幅周波数特性と周期スプリアス特性を
それぞれ示す図、第９図は第７図に示す装置の表面波発
生態様を説明する概略平面図、第１Ｏ図及び第１１図は
第７図に示す装置の周期スプリアスを確認するための実
験例をそれぞれ概略的に示す部分平面図、第１２図は第
１１図の実験例の周期スプリアス特性図である。
２０−−一−−−−−−−基板、
２１．２３−−−−−−−＜ｔ、ば状電極。
２１ａ、２３ ａ −−−−一電極指、２１ｂ、２２−
−−−−一共通電極、
２２Ａ、３２Ａ−−−−一屈折部、
２２ａ、３２ ａ −−−−一傾斜端縁、２５．３０、
−一一一一一吸音材、
（他１名）
加−−一一一−−−−−基板
２１．２３−−−−−−−＜Ｌぼ状を極２１ａ 、
２２釦 −一−−−電糧指２１ｂ 、 ２２−一−−
−−共通電極２２Ａ−−−−−−−−一屈ｔ／ｒ１！８
２２ａ −−−−一−−−−傾斜′＠縁２５ −−−−
−−−−一吸盲材
２６．２７−−−−−−−吸音部
第３図
第５図
第６図
第８図
（Ａ）
第１２図1 and 2 are a plan view of a surface acoustic wave device according to the present invention and a schematic plan view illustrating its operation, and FIG. 3 shows the main parts of the device shown in FIG. FIG. 4 is a plan view of an apparatus according to another embodiment of the present invention, FIG. 5 is a schematic plan view of an apparatus according to still another embodiment of the present invention, FIG. FIG. 7 is a plan view showing a conventional surface acoustic wave device equipped with a 7-potized comb-like electrode with an inclined electrode structure, and FIG.
9 is a schematic plan view illustrating the surface wave generation mode of the device shown in FIG. 7, and FIGS. FIG. 12 is a partial plan view schematically showing experimental examples for confirming periodic spurious of the apparatus shown in FIG. 12, and FIG. 12 is a periodic spurious characteristic diagram of the experimental example of FIG. 20--1---------Substrate, 21.23-----<t, bar-shaped electrode. 21a, 23a ----one electrode finger, 21b, 22-
----One common electrode, 22A, 32A---One bending part, 22a, 32a---One inclined edge, 25.30,
-11111 sound absorbing material, (1 other person) addition--111---- Substrate 21.23----< L-shaped pole 21a,
22 button -1---Electric food finger 21b, 22-1---
--Common electrode 22A----Ikkut/r1!8
22a -----1---- Incline'@edge 25 ----
---Socket blind material 26.27-----Sound absorption part Figure 3 Figure 5 Figure 6 Figure 8 (A) Figure 12
Claims (3)
電極指及び該電極指が接続されている共通電極を有する
くしば状電極を備える弾性表面波装置において、前記共
通電極は対向する他のくしば状電極より離間する部分が
前記電極指の非交差部の長さ寸法を徐々に小さくする方
向に屈折し、かつ該屈折部が表面波の伝搬方向に対して
角度を有する傾斜端縁を有することを特徴とする弾性表
面波装置。(1) In a surface acoustic wave device comprising a comb-like electrode having electrode fingers whose intersection length changes in response to an impulse response and a common electrode to which the electrode fingers are connected, the common electrodes are arranged opposite to each other, and an inclined edge whose portion separated from the comb-like electrode is bent in a direction that gradually reduces the length of the non-intersecting portion of the electrode fingers, and the bent portion is at an angle with respect to the propagation direction of the surface wave; A surface acoustic wave device comprising:
を特徴とする特許請求の範囲第１項に記載の弾性表面波
装置。(2) The surface acoustic wave device according to claim 1, wherein a sound absorbing material is arranged near the common electrode.
に対して偏移させるべく前記電極指の交差位置を傾斜さ
せた傾斜電極構造を有することを特徴とする特許請求の
範囲第１項に記載の弾性表面波装置。(3) The comb-shaped electrode has an inclined electrode structure in which the intersecting position of the electrode fingers is inclined so as to shift the side lobe with respect to the main lobe. surface acoustic wave device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10057287A JPS63266913A (en) | 1987-04-22 | 1987-04-22 | Surface acoustic wave device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10057287A JPS63266913A (en) | 1987-04-22 | 1987-04-22 | Surface acoustic wave device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63266913A true JPS63266913A (en) | 1988-11-04 |
Family
ID=14277618
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10057287A Pending JPS63266913A (en) | 1987-04-22 | 1987-04-22 | Surface acoustic wave device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63266913A (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53143147A (en) * | 1977-05-20 | 1978-12-13 | Murata Manufacturing Co | Elastic surface wave device |
| JPS5412542A (en) * | 1977-06-29 | 1979-01-30 | Hitachi Ltd | Elastic surface wave unit |
| JPS5487495A (en) * | 1977-12-21 | 1979-07-11 | Tektronix Inc | Surface elastic wave converter |
| JPS58190117A (en) * | 1982-04-19 | 1983-11-07 | エヌ・ベ−・フイリツプス・フル−イランペンフアブリケン | Acoustic surface wave device and band filter with same |
| JPS60256207A (en) * | 1984-06-01 | 1985-12-17 | Matsushita Electric Ind Co Ltd | Manufacture of elastic wave device |
| JPS6129207A (en) * | 1984-07-19 | 1986-02-10 | Matsushita Electric Ind Co Ltd | Elastic wave device |
| JPS61245613A (en) * | 1984-12-17 | 1986-10-31 | シ−メンス、アクチエンゲゼルシヤフト | Electric surface elastic wave filter |
-
1987
- 1987-04-22 JP JP10057287A patent/JPS63266913A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53143147A (en) * | 1977-05-20 | 1978-12-13 | Murata Manufacturing Co | Elastic surface wave device |
| JPS5412542A (en) * | 1977-06-29 | 1979-01-30 | Hitachi Ltd | Elastic surface wave unit |
| JPS5487495A (en) * | 1977-12-21 | 1979-07-11 | Tektronix Inc | Surface elastic wave converter |
| JPS58190117A (en) * | 1982-04-19 | 1983-11-07 | エヌ・ベ−・フイリツプス・フル−イランペンフアブリケン | Acoustic surface wave device and band filter with same |
| JPS60256207A (en) * | 1984-06-01 | 1985-12-17 | Matsushita Electric Ind Co Ltd | Manufacture of elastic wave device |
| JPS6129207A (en) * | 1984-07-19 | 1986-02-10 | Matsushita Electric Ind Co Ltd | Elastic wave device |
| JPS61245613A (en) * | 1984-12-17 | 1986-10-31 | シ−メンス、アクチエンゲゼルシヤフト | Electric surface elastic wave filter |
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