JP2005303486A - Ultrasonic sensor - Google Patents

Ultrasonic sensor Download PDF

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JP2005303486A
JP2005303486A JP2004113750A JP2004113750A JP2005303486A JP 2005303486 A JP2005303486 A JP 2005303486A JP 2004113750 A JP2004113750 A JP 2004113750A JP 2004113750 A JP2004113750 A JP 2004113750A JP 2005303486 A JP2005303486 A JP 2005303486A
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vibration
ultrasonic sensor
body portion
piezoelectric
vibration element
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Koji Urase
浩司 浦瀬
Naoya Azuma
直哉 東
Susumu Katayama
進 片山
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Panasonic Electric Works Co Ltd
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Matsushita Electric Works Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/521—Constructional features
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/93—Sonar systems specially adapted for specific applications for anti-collision purposes
    • G01S15/931—Sonar systems specially adapted for specific applications for anti-collision purposes of land vehicles

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ultrasonic sensor in which reverberation vibration is suppressed and an influence of sub-resonance points other than main vibration can be suppressed without employing a damping member. <P>SOLUTION: The ultrasonic sensor 1 comprises a case 4 having a vibrator section 5, and a piezoelectric vibration element 2 abutting against the vibrator section 5 and vibrating the vibrator section 5 in the case 4. The vibrator section 5 has an elongated rectangular or elliptical vibration plane. The piezoelectric vibration element 2 has outline similar to the vibration plane of the vibrator section 5 and substantially same size as that of the vibration plane of the vibrator section 5. Since the outline of the piezoelectric vibration element 2 is similar to the vibration plane of the vibrator section 5, a profile of the piezoelectric vibration element 2 is increased, and reverberation vibration is suppressed by preventing capacitance of the piezoelectric vibration element 2 from decreasing. Since the vibration plane of the vibrator section 5 and the outline of the piezoelectric vibration element 2 have an elongated shape, the influence of sub-resonance points other than main vibration on the vibrator section 5 is suppressed without employing a damping member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、超音波を発信し、その反射波を受信して物体を検出する超音波センサに関するものである。   The present invention relates to an ultrasonic sensor that detects an object by transmitting an ultrasonic wave and receiving a reflected wave thereof.

従来から、超音波センサにおいて、有底状のケースの内底面を振動体部とし、この振動体部を圧電振動素子にて振動させることにより超音波を発信するようにしたものが知られている（例えば、特許文献１及び特許文献２参照）。このような超音波センサは、例えば車両周辺の物体を検知する車両用周辺監視装置等に用いられる。   2. Description of the Related Art Conventionally, an ultrasonic sensor is known in which an inner bottom surface of a bottomed case is used as a vibrating body portion, and the vibrating body portion is vibrated by a piezoelectric vibrating element to transmit ultrasonic waves. (For example, refer to Patent Document 1 and Patent Document 2). Such an ultrasonic sensor is used, for example, in a vehicle periphery monitoring device that detects an object around the vehicle.

特許文献１に記載の超音波センサは、図３（ａ）（ｂ）（ｃ）に示す構成になっている。すなわち、超音波センサ８０は、有底状のケース８１の底面が平板状の振動体部（フラット型のマイク）８２とされ、圧電振動素子８３がケース８１内にて振動体部８２に貼付けられている。振動体部８２は、トラック形状（略長方形又は略長円形）に形成されており、圧電振動素子８３は、略円形に形成されている。   The ultrasonic sensor described in Patent Document 1 has a configuration shown in FIGS. 3 (a), 3 (b), and 3 (c). That is, in the ultrasonic sensor 80, the bottom surface of the bottomed case 81 is a flat vibrating body portion (flat microphone) 82, and the piezoelectric vibrating element 83 is attached to the vibrating body portion 82 in the case 81. ing. The vibrating body portion 82 is formed in a track shape (substantially rectangular or substantially oval), and the piezoelectric vibrating element 83 is formed in a substantially circular shape.

また、吸音材８４がケース８１内に配置され、さらに、絶縁性材料８５がケース８１内に充填されている。圧電振動素子８３は、半田８６を介してリード線８７に接続されていると共に、ケース８１内にインサート成形された導電部材（不図示）を介してリード線８８に接続されている。振動体部８２の内面の外周部には、主振動以外の副共振を抑制するダンピング用の絶縁性材料８９が封止されている。   Further, the sound absorbing material 84 is disposed in the case 81, and the insulating material 85 is further filled in the case 81. The piezoelectric vibration element 83 is connected to the lead wire 87 via the solder 86 and is connected to the lead wire 88 via a conductive member (not shown) insert-molded in the case 81. A damping insulating material 89 that suppresses sub-resonance other than main vibration is sealed on the outer peripheral portion of the inner surface of the vibrating body portion 82.

このような構成の超音波センサ８０は、交流電圧がリード線８７、８８を介して圧電振動素子８３に印加されることにより、圧電振動素子８３が歪み、振動体部８２が振動して、矢印Ｐ方向に超音波を発信する。また、超音波センサ８０は、超音波を受けると、振動体部８２が振動し、圧電振動素子８３が歪んで電気信号を発生して、その電気信号をリード線８７、８８から出力する。そして、その電気信号に基づいて、物体の有無、物体までの距離等の検出処理が行われる。   In the ultrasonic sensor 80 having such a configuration, when an AC voltage is applied to the piezoelectric vibration element 83 via the lead wires 87 and 88, the piezoelectric vibration element 83 is distorted and the vibration body portion 82 vibrates, so that the arrow Sends ultrasonic waves in the P direction. Further, when the ultrasonic sensor 80 receives the ultrasonic wave, the vibrating body portion 82 vibrates, the piezoelectric vibration element 83 is distorted to generate an electric signal, and the electric signal is output from the lead wires 87 and 88. Based on the electrical signal, detection processing such as the presence / absence of an object and the distance to the object is performed.

また、特許文献２に記載の超音波センサは、振動体部が略円形とされており、圧電振動素子も略円形とされている。この特許文献２に記載の超音波センサの他の構成は、上記特許文献１に記載の超音波センサの構成と同様である。   Further, in the ultrasonic sensor described in Patent Document 2, the vibrating body portion is substantially circular, and the piezoelectric vibration element is also substantially circular. Other configurations of the ultrasonic sensor described in Patent Document 2 are the same as the configurations of the ultrasonic sensor described in Patent Document 1.

これらの超音波センサによれば、振動体部の振動面に直交する軸寸法を任意に変更することで、超音波の指向特性を任意に設定することが可能である。また、振動体部が平板状（フラット型マイク）であるため、外観を損ねず、ホーン型マイクと同等な特性を得ることが可能である。
実用新案登録第３０３４６８５号公報 特開２０００−２３２９０号公報 According to these ultrasonic sensors, it is possible to arbitrarily set the directivity characteristics of ultrasonic waves by arbitrarily changing the axial dimension orthogonal to the vibration surface of the vibrating body portion. Moreover, since the vibrating body portion is flat (flat type microphone), it is possible to obtain the same characteristics as the horn type microphone without impairing the appearance.
Utility Model Registration No. 3034685 JP 2000-23290 A

ところで、上述した従来の超音波センサにおいては、近年、意匠向上のためにマイク（振動体部）の小型化が要求され、このため、圧電振動素子の貼付けスペースが小さくなり、その結果、必然的に圧電振動素子の形状を小さくしなければならず、圧電振動素子の静電容量が低下してしまい、低残響を図ることができない状況となっている。また、垂直方向の指向特性を狭角化させるためには振動体部の寸法を大きくする必要があるが、振動体部の寸法を大きくすると、主振動以外の副共振点が生じてしまう。このため、副共振点を小さく若しくは無くすために、シリコン等の絶縁性材料をケースの底部（振動体部の外周部）にダンピング効果として封止させており、その封止作業のために生産性の向上を図ることが困難となっている。   By the way, in the conventional ultrasonic sensor described above, in recent years, it is required to reduce the size of the microphone (vibrating body portion) in order to improve the design. Therefore, the space for attaching the piezoelectric vibrating element is reduced, and as a result, it is inevitable. In addition, it is necessary to reduce the shape of the piezoelectric vibration element, the capacitance of the piezoelectric vibration element is reduced, and low reverberation cannot be achieved. Further, in order to narrow the vertical directivity, it is necessary to increase the size of the vibrating body portion. However, if the size of the vibrating body portion is increased, a sub-resonance point other than the main vibration is generated. For this reason, in order to reduce or eliminate the sub-resonance point, an insulating material such as silicon is sealed as a damping effect at the bottom of the case (the outer periphery of the vibrating body), and productivity is improved for the sealing work. It is difficult to improve.

本発明は、上記課題を解決するためになされたものであり、振動体部の小型化による圧電振動素子の静電容量の低下を防いで残響振動を抑制できると共に、ダンピングを行うことなく主振動以外の副共振点による影響を抑制できる超音波センサを提供することを目的とする。   The present invention has been made in order to solve the above-mentioned problems, and can prevent reverberation vibration by preventing a decrease in the capacitance of the piezoelectric vibration element due to downsizing of the vibration body portion, and can suppress main vibration without performing damping. An object of the present invention is to provide an ultrasonic sensor capable of suppressing the influence of sub-resonance points other than the above.

上記目的を達成するために請求項１の発明は、平板状の振動体部を有するケースと、このケース内にて振動体部に当接され振動体部を振動させる圧電振動素子とを備える超音波センサにおいて、振動体部は、振動面が細長形状であり、圧電振動素子は、その外形が振動体部の振動面と相似形状に形成されているものである。   In order to achieve the above object, an invention according to claim 1 includes a case having a flat plate-like vibrating body portion, and a piezoelectric vibrating element that abuts on the vibrating body portion and vibrates the vibrating body portion in the case. In the acoustic wave sensor, the vibration body portion has an elongated vibration surface, and the piezoelectric vibration element has an outer shape similar to the vibration surface of the vibration body portion.

請求項２の発明は、請求項１に記載の超音波センサにおいて、圧電振動素子は、その外形が矩形状又は長円形状とされているものである。   According to a second aspect of the present invention, in the ultrasonic sensor according to the first aspect, the outer shape of the piezoelectric vibration element is rectangular or oval.

請求項３の発明は、請求項１に記載の超音波センサにおいて、圧電振動素子は、その外形が振動体部の振動面と略同じ大きさとされているものである。   According to a third aspect of the present invention, in the ultrasonic sensor according to the first aspect, the outer shape of the piezoelectric vibration element is substantially the same as the vibration surface of the vibration body portion.

請求項１の発明によれば、圧電振動素子の外形を振動体部の振動面と相似形状とすることにより、圧電振動素子の形状を大きくすることが可能となり、圧電振動素子の静電容量の低下を防いで残響振動を抑制することができる。これにより、発信した超音波の近距離からの反射波の識別が可能となり、近距離での物体の検出を正確に行うことができる。しかも、振動体部の振動面及び圧電振動素子の外形を細長形状とすることにより、従来のようにダンピング用の部材を用いることなく主振動以外の副共振点の影響を抑制することができる。これにより、物体の検出を正確に行うことができ、また、ダンピング用の部材を用いる必要がないため生産性が向上する。   According to the first aspect of the invention, by making the outer shape of the piezoelectric vibration element similar to the vibration surface of the vibrating body portion, it is possible to increase the shape of the piezoelectric vibration element, and to reduce the capacitance of the piezoelectric vibration element. The reverberation vibration can be suppressed by preventing the decrease. Thereby, it becomes possible to identify a reflected wave from a short distance of the transmitted ultrasonic wave, and it is possible to accurately detect an object at a short distance. In addition, by making the vibration surface of the vibrating body portion and the outer shape of the piezoelectric vibration element elongated, it is possible to suppress the influence of sub-resonance points other than the main vibration without using a damping member as in the prior art. As a result, the object can be accurately detected, and the productivity is improved because it is not necessary to use a damping member.

請求項２の発明によれば、圧電振動素子の外形を矩形状又は長円形状とすることにより、副共振点の影響をより一層抑制することができ、物体の検出をより一層正確に行うことができる。   According to the invention of claim 2, by making the outer shape of the piezoelectric vibration element rectangular or oval, the influence of the secondary resonance point can be further suppressed, and the object can be detected more accurately. Can do.

請求項３の発明によれば、圧電振動素子の外形を振動体部の振動面と略同じ大きさとすることにより、圧電振動素子の大きさを最も大きくでき、これにより、残響振動をより一層抑制することができ、近距離での物体の検出をより一層正確に行うことができる。   According to the third aspect of the present invention, the size of the piezoelectric vibration element can be maximized by making the outer shape of the piezoelectric vibration element substantially the same as the vibration surface of the vibrating body portion, thereby further suppressing reverberation vibration. This makes it possible to detect an object at a short distance even more accurately.

以下、本発明を具体化した実施形態について図面を参照して説明する。図１（ａ）（ｂ）（ｃ）において、超音波センサ１は、例えば車両周辺の物体を検知する車両用周辺監視装置等に用いられるセンサであり、超音波を発信し、その反射波を受信して物体を検出するセンサである。   DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. In FIGS. 1A, 1B, and 1C, an ultrasonic sensor 1 is a sensor that is used in, for example, a vehicle periphery monitoring device that detects an object around a vehicle, and transmits ultrasonic waves and reflects the reflected waves. It is a sensor that receives and detects an object.

超音波センサ１は、超音波を発生させるための圧電振動素子２と、超音波を吸音する吸音材３と、圧電振動素子２及び吸音材３を収納するケース４とを備えている。ケース４は、有底略円筒状であり、超音波を発信・受信するための振動体部５を有しており、ケース４の底面が振動体部５とされている。圧電振動素子２は、振動体部５の内面に貼付けられており、ケース４内にて振動体部５に当接している。吸音材３は、圧電振動素子２及び振動体部５との間に空間を介して配置されている。   The ultrasonic sensor 1 includes a piezoelectric vibration element 2 for generating ultrasonic waves, a sound absorbing material 3 for absorbing ultrasonic waves, and a case 4 for housing the piezoelectric vibration element 2 and the sound absorbing material 3. The case 4 has a substantially cylindrical shape with a bottom, has a vibrating body portion 5 for transmitting and receiving ultrasonic waves, and the bottom surface of the case 4 is the vibrating body portion 5. The piezoelectric vibration element 2 is affixed to the inner surface of the vibrating body portion 5 and is in contact with the vibrating body portion 5 in the case 4. The sound absorbing material 3 is disposed between the piezoelectric vibrating element 2 and the vibrating body portion 5 via a space.

また、超音波センサ１は、圧電振動素子２を駆動し、又は圧電振動素子２からの信号を送出するリード線６、８を備え、一方のリード線６は半田７を介して圧電振動素子２に接続されると共に、他方のリード線８は導電部材（不図示）を介して圧電振動素子２に接続されている。ケース４内には、絶縁性材料９が充填されている。   The ultrasonic sensor 1 includes lead wires 6 and 8 that drive the piezoelectric vibration element 2 or send a signal from the piezoelectric vibration element 2, and the one lead wire 6 is connected to the piezoelectric vibration element 2 via the solder 7. And the other lead wire 8 is connected to the piezoelectric vibration element 2 via a conductive member (not shown). The case 4 is filled with an insulating material 9.

このような構成の超音波センサ１において、交流電圧がリード線６、８を介して圧電振動素子２に印加されることにより、圧電振動素子２が歪んで振動体部５を振動させ、振動体部５が振動することにより、矢印Ｑの方向に超音波を発信する。また、振動体部５にて超音波を受信すると、振動体部５が振動し、圧電振動素子２が振動体部５の振動により歪んで電気信号を発生して、その電気信号をリード線６、８から出力する。そして、その電気信号に基づいて、物体の有無や物体までの距離等の検出処理が行われる。   In the ultrasonic sensor 1 having such a configuration, when an AC voltage is applied to the piezoelectric vibration element 2 via the lead wires 6 and 8, the piezoelectric vibration element 2 is distorted to vibrate the vibration body portion 5. When the unit 5 vibrates, an ultrasonic wave is transmitted in the direction of the arrow Q. In addition, when the ultrasonic wave is received by the vibrating body unit 5, the vibrating body unit 5 vibrates, and the piezoelectric vibration element 2 is distorted by the vibration of the vibrating body unit 5 to generate an electric signal. , 8 are output. Based on the electrical signal, detection processing such as the presence / absence of an object and the distance to the object is performed.

上記振動体部５は、平板状であり、振動面が細長のトラック形状（略長方形又は略長円形）に形成されている。また、上記圧電振動素子２は、その外形が振動体部５の振動面と相似形状（すなわちトラック形状）に形成されており、また、振動体部５の振動面と略同じ大きさに形成されている。   The vibrating body portion 5 has a flat plate shape, and the vibration surface is formed in an elongated track shape (substantially rectangular or substantially oval). The piezoelectric vibration element 2 has an outer shape similar to that of the vibration surface of the vibration body portion 5 (that is, a track shape), and is substantially the same size as the vibration surface of the vibration body portion 5. ing.

このような構成の本発明の超音波センサ１と、図３（ａ）（ｂ）（ｃ）に示す従来の（すなわち、振動体部の振動面が細長のトラック形状であり、圧電振動素子の外形が円形状である）超音波センサ８０について、圧電振動素子の静電容量を測定する実験を行った。実験の結果、従来の超音波センサ８０では、静電容量が２１７１ｐＦであるのに対し、本発明の超音波センサ１では、静電容量が５１６８ｐＦであった。すなわち、この実験から、本発明の超音波センサ１は従来の超音波センサ８０よりも静電容量が大きいという結果が得られた。また、ｆ＝１／２π√（ＬＣ）の関係により、ｆ、すなわち周波数が一定の場合、静電容量が大きくなれば、圧電振動素子の等価回路定数のＬ（リアクタンス）値が小さくなるため、本発明の超音波センサ１は従来の超音波センサ８０よりもＬ値が小さいという結果が導かれる。   The ultrasonic sensor 1 of the present invention having the above-described configuration and the conventional (ie, the vibrating surface of the vibrating body portion has an elongated track shape shown in FIGS. 3A, 3B, and 3C), and the piezoelectric vibrating element With respect to the ultrasonic sensor 80 (whose outer shape is a circular shape), an experiment for measuring the capacitance of the piezoelectric vibration element was performed. As a result of the experiment, the conventional ultrasonic sensor 80 has a capacitance of 2171 pF, whereas the ultrasonic sensor 1 of the present invention has a capacitance of 5168 pF. That is, from this experiment, the ultrasonic sensor 1 of the present invention has a larger capacitance than the conventional ultrasonic sensor 80. Further, according to the relationship of f = 1 / 2π√ (LC), when f, that is, when the frequency is constant, if the capacitance increases, the L (reactance) value of the equivalent circuit constant of the piezoelectric vibration element decreases. As a result, the ultrasonic sensor 1 of the present invention has a smaller L value than the conventional ultrasonic sensor 80.

また、圧電振動素子の等価回路定数のＬ値が異なる場合について、残響時間を測定する実験を行った。実験の結果、Ｌ値が１００ｍＨの場合では、残響時間が１．０ｍｓｅｃであるのに対し、Ｌ値が８０ｍＨの場合では、残響時間が０．９ｍｓｅｃであった。すなわち、この実験から、Ｌ値が小さい方が残響時間が短いという結果が得られた。従って、この実験結果、及び上記の本発明の超音波センサ１は従来の超音波センサ８０よりも静電容量が大きくＬ値が小さいという実験結果から、本発明の超音波センサ１は従来の超音波センサ８０よりも残響時間が短いという結果が導かれる。   In addition, an experiment for measuring the reverberation time was performed when the L values of the equivalent circuit constants of the piezoelectric vibration elements were different. As a result of the experiment, when the L value was 100 mH, the reverberation time was 1.0 msec, whereas when the L value was 80 mH, the reverberation time was 0.9 msec. That is, from this experiment, a result that the reverberation time was shorter when the L value was smaller was obtained. Therefore, from this experimental result and the experimental result that the ultrasonic sensor 1 of the present invention has a larger capacitance and a smaller L value than the conventional ultrasonic sensor 80, the ultrasonic sensor 1 of the present invention is a conventional ultrasonic sensor. The result is that the reverberation time is shorter than that of the acoustic wave sensor 80.

また、本発明の超音波センサ１と従来の超音波センサ８０について、圧電振動素子のインピーダンス特性を測定する実験を行った。従来の超音波センサ８０におけるインピーダンス特性を図２（ａ）に、本発明の超音波センサ１におけるインピーダンス特性を図２（ｂ）に示す。図２（ａ）（ｂ）において、横軸は振動周波数であり、縦軸はインピーダンスである。なお、従来の超音波センサ８０は、副共振を抑制するダンピング用の絶縁性材料８９が封止されていない構成で実験を行った。   In addition, with respect to the ultrasonic sensor 1 of the present invention and the conventional ultrasonic sensor 80, an experiment for measuring impedance characteristics of the piezoelectric vibration element was performed. FIG. 2A shows the impedance characteristics of the conventional ultrasonic sensor 80, and FIG. 2B shows the impedance characteristics of the ultrasonic sensor 1 of the present invention. 2A and 2B, the horizontal axis is the vibration frequency, and the vertical axis is the impedance. Note that the conventional ultrasonic sensor 80 was tested in a configuration in which the damping insulating material 89 that suppresses sub-resonance is not sealed.

実験の結果、従来の超音波センサ８０では、図２（ａ）から明らかなように、図中Ｕ１で示す箇所に主振動が存在し、図中Ｕ２で示す箇所に副共振点が存在している。一方、本発明の超音波センサ１では、図２（ｂ）から明らかなように、図中Ｖ１で示す箇所に主振動が存在し、図中Ｖ２で示す箇所（図２（ａ）のＵ２に対応する箇所）には副共振点が存在しておらず、また、他の何れの箇所にも副共振点が存在していない。すなわち、この実験から、本発明の超音波センサ１は従来の超音波センサ８０では生じる副共振が生じないことが明らかとなった。   As a result of the experiment, in the conventional ultrasonic sensor 80, as is clear from FIG. 2A, the main vibration is present at the location indicated by U1 in the figure, and the secondary resonance point is present at the location indicated by U2 in the figure. Yes. On the other hand, in the ultrasonic sensor 1 of the present invention, as is clear from FIG. 2B, the main vibration is present at the position indicated by V1 in the figure, and the position indicated by V2 in the figure (in U2 in FIG. 2A). There is no sub-resonance point at the corresponding location), and there is no sub-resonance point at any other location. That is, from this experiment, it has been clarified that the ultrasonic sensor 1 of the present invention does not generate sub-resonance that occurs in the conventional ultrasonic sensor 80.

このように、本発明の超音波センサ１では、振動体部５の振動面を細長のトラック形状（略長方形又は略長円形）にし、圧電振動素子２の外形を振動体部５の振動面と相似形状にすると共に振動体部５の振動面と略同じ大きさにすることにより、圧電振動素子２の静電容量の低下を防いで残響振動を抑制ができ、しかも、従来のようにダンピング用の部材を用いる（シリコン等の絶縁性材料を振動体部の外周部に封止させる）ことなく主振動以外の副共振点の発生を抑制できる。   As described above, in the ultrasonic sensor 1 of the present invention, the vibration surface of the vibration body portion 5 is formed into a slender track shape (substantially rectangular or substantially oval), and the outer shape of the piezoelectric vibration element 2 is the vibration surface of the vibration body portion 5. The resonating vibration can be suppressed by reducing the electrostatic capacity of the piezoelectric vibration element 2 by making it similar and having substantially the same size as the vibration surface of the vibrating body portion 5, and for damping as in the conventional case. The generation of sub-resonance points other than the main vibration can be suppressed without using the above member (sealing the insulating material such as silicon on the outer periphery of the vibrating body).

従って、本発明の超音波センサ１によれば、残響振動を抑制できるため、発信した超音波の近距離からの反射波の識別が可能となり、近距離での物体の検出を正確に行うことができる。しかも、主振動以外の副共振点の発生を抑制できるため、物体の検出をさらに正確に行うことができる。また、副共振点の発生を抑制するの従来のようにダンピング用の部材を用いる必要がないため、生産性が向上する。   Therefore, according to the ultrasonic sensor 1 of the present invention, since reverberation vibration can be suppressed, it is possible to identify a reflected wave from a short distance of the transmitted ultrasonic wave, and to accurately detect an object at a short distance. it can. In addition, since the occurrence of sub-resonance points other than the main vibration can be suppressed, the object can be detected more accurately. Further, since it is not necessary to use a damping member as in the conventional case of suppressing the occurrence of the secondary resonance point, productivity is improved.

なお、本発明は、上記実施形態の構成に限られず、種々の変形が可能である。例えば、上記実施形態において、振動体部５の振動面は、必ずしもトラック形状（長方形又は長円形）に限られず、細長形状であれば、例えば楕円形状や多角形状であってもよい。この場合、圧電振動素子２の外形を振動体部５の振動面の形状に合った相似形状とすればよい。このような構成によっても、上記実施形態と同様の効果が得られる。また、圧電振動素子２の外形は、必ずしも振動体部５の振動面と同じ大きさに限られず、振動体部５の振動面と相似形状であれば、振動体部５の振動面よりもある程度小さくてもよい。このような構成によっても、上記実施形態と同様の効果が得られる。   In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible. For example, in the above-described embodiment, the vibration surface of the vibrating body portion 5 is not necessarily limited to the track shape (rectangular or oval), and may be, for example, an elliptical shape or a polygonal shape as long as it is an elongated shape. In this case, the outer shape of the piezoelectric vibration element 2 may be a similar shape that matches the shape of the vibration surface of the vibrating body portion 5. Even with such a configuration, the same effect as in the above embodiment can be obtained. In addition, the outer shape of the piezoelectric vibration element 2 is not necessarily limited to the same size as the vibration surface of the vibration body portion 5. If the shape is similar to the vibration surface of the vibration body portion 5, the outer shape of the piezoelectric vibration element 2 is somewhat larger than the vibration surface of the vibration body portion 5. It may be small. Even with such a configuration, the same effect as in the above embodiment can be obtained.

（ａ）は本発明の一実施形態に係る超音波センサの構成を示す平面図、（ｂ）は（ａ）のＡ−Ａ断面図、（ｃ）は（ａ）のＢ−Ｂ断面図。(A) is a top view which shows the structure of the ultrasonic sensor which concerns on one Embodiment of this invention, (b) is AA sectional drawing of (a), (c) is BB sectional drawing of (a). （ａ）は同超音波センサの圧電振動素子のインピーダンス特性を示す図、（ｂ）は従来の超音波センサの圧電振動素子のインピーダンス特性を示す図。(A) is a figure which shows the impedance characteristic of the piezoelectric vibration element of the ultrasonic sensor, (b) is a figure which shows the impedance characteristic of the piezoelectric vibration element of the conventional ultrasonic sensor. （ａ）は従来の超音波センサの構成を示す平面図、（ｂ）は（ａ）のＣ−Ｃ断面図、（ｃ）は（ａ）のＤ−Ｄ断面図。(A) is a top view which shows the structure of the conventional ultrasonic sensor, (b) is CC sectional drawing of (a), (c) is DD sectional drawing of (a).

符号の説明Explanation of symbols

１ 超音波センサ
２ 圧電振動素子
３ 吸音材
４ ケース
５ 振動体部
６、８ リード線
７ 半田
９ 絶縁性材料 DESCRIPTION OF SYMBOLS 1 Ultrasonic sensor 2 Piezoelectric vibration element 3 Sound absorption material 4 Case 5 Vibrating body part 6, 8 Lead wire 7 Solder 9 Insulating material

Claims (3)

平板状の振動体部を有するケースと、このケース内にて前記振動体部に当接され振動体部を振動させる圧電振動素子とを備える超音波センサにおいて、
前記振動体部は、振動面が細長形状であり、
前記圧電振動素子は、その外形が前記振動体部の振動面と相似形状に形成されていることを特徴とする超音波センサ。 In an ultrasonic sensor comprising: a case having a flat plate-like vibrating body portion; and a piezoelectric vibrating element that is in contact with the vibrating body portion and vibrates the vibrating body portion in the case
The vibrating body portion has an elongated vibration surface,
2. The ultrasonic sensor according to claim 1, wherein the piezoelectric vibration element has an outer shape similar to a vibration surface of the vibration body portion. 前記圧電振動素子は、その外形が矩形状又は長円形状とされていることを特徴とする請求項１に記載の超音波センサ。   The ultrasonic sensor according to claim 1, wherein an outer shape of the piezoelectric vibration element is a rectangular shape or an oval shape. 前記圧電振動素子は、その外形が前記振動体部の振動面と略同じ大きさとされていることを特徴とする請求項１に記載の超音波センサ。


2. The ultrasonic sensor according to claim 1, wherein an outer shape of the piezoelectric vibration element is substantially the same as a vibration surface of the vibration body portion.


JP2004113750A 2004-04-08 2004-04-08 Ultrasonic sensor Pending JP2005303486A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008170306A (en) * 2007-01-12 2008-07-24 Mitsubishi Electric Corp Evaluation method of ranging sensor
JP2010050963A (en) * 2008-07-25 2010-03-04 Sumitomo Chemical Co Ltd Ultrasonic sensor case and ultrasonic sensor
US7984290B2 (en) 2005-05-20 2011-07-19 Hitachi, Ltd. System and method for encrypted communication

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7984290B2 (en) 2005-05-20 2011-07-19 Hitachi, Ltd. System and method for encrypted communication
JP2008170306A (en) * 2007-01-12 2008-07-24 Mitsubishi Electric Corp Evaluation method of ranging sensor
JP2010050963A (en) * 2008-07-25 2010-03-04 Sumitomo Chemical Co Ltd Ultrasonic sensor case and ultrasonic sensor

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