JP3435065B2 - Piezoelectric acceleration sensor - Google Patents
Piezoelectric acceleration sensorInfo
- Publication number
- JP3435065B2 JP3435065B2 JP21497498A JP21497498A JP3435065B2 JP 3435065 B2 JP3435065 B2 JP 3435065B2 JP 21497498 A JP21497498 A JP 21497498A JP 21497498 A JP21497498 A JP 21497498A JP 3435065 B2 JP3435065 B2 JP 3435065B2
- Authority
- JP
- Japan
- Prior art keywords
- case
- piezoelectric
- inner case
- piezoelectric acceleration
- sensor
- 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
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- Cooling Or The Like Of Electrical Apparatus (AREA)
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、温度変化が激しい
環境に適応する圧電式加速度センサに関する。
【０００２】
【従来の技術】従来、屋外に設置される圧電式加速度セ
ンサとして圧電式感震器等がある。この種の圧電式感震
器は、図３に示すように、ケース１００内部に圧電式加
速度検出部１０１、圧電式加速度検出部１０１の出力信
号を処理する電気回路が形成されたプリント基板１０２
等を配設してなる。ここで、圧電式加速度検出部１０１
は、特許第２５８１９０１号公報に記載のものと同一の
構成により、３方向の加速度を検出することが可能であ
る。
【０００３】
【発明が解決しようとする課題】しかし、図３に示す従
来の圧電式感震器においては、温度変化が激しい環境に
設置された場合、ケース１００内部に結露が生じて圧電
式加速度検出部１０１の圧電素子の絶縁を低下させた
り、電気回路部が形成されているプリント基板１０２を
腐食させたりするという問題があった。圧電素子の絶縁
が低下すると、圧電式加速度検出部１０１のＳ／Ｎ比が
低下してしまい、微弱な振動を検出する感震器として好
ましくないからである。
【０００４】本発明は、従来の技術が有するこのような
問題点に鑑みてなされたものであり、その目的とすると
ころは、設置される環境の温度変化によって発生する結
露の影響を少なくすることにより、信頼性の高い圧電式
加速度センサを提供しようとするものである。
【０００５】
【課題を解決するための手段】上記課題を解決すべく請
求項１に係る発明は、ケース内部に四角柱の４面に圧電
素子と錘を突出させて取り付けてなる３方向圧電式加速
度検出部を有する圧電式加速度センサにおいて、前記ケ
ース内部に中空円筒形状の内ケースを配設すると共に、
この内ケースの内部に前記３方向圧電式加速度検出部を
固定し、前記内ケースと前記３方向圧電式加速度検出部
とで形成される空間を縮小する張り出し部を前記内ケー
スの内面に突出形成したものである。
【０００６】
【０００７】
【０００８】
【発明の実施の形態】以下に本発明の実施の形態を添付
図面に基づいて説明する。ここで、図１は本発明に係る
３方向圧電式感震器の部分縦断面図、図２は本発明に係
る３方向圧電式感震器の部分横断面図である。
【０００９】本発明に係る３方向圧電式感震器は、図１
又は図２に示すように、ケース１、内ケース２、３方向
圧電式加速度検出部３、電子部品が実装されたプリント
基板４、張り出し部５、コネクタ６等からなる。
【００１０】ケース１は、アルミ合金等の金属部材から
なる上ケース部材１ａと下ケース部材１ｂを密着するこ
とで、中空の円柱形状の完全密閉ケースを形成してい
る。
【００１１】内ケース２は、アルミ合金等の金属部材か
らなり、ケース１内部において空気と接する表面積を増
大させるためにケース１の底面に絶縁部材２ｂを介して
固定されている。また、内ケース２の上面にリード線を
通す孔部２ａが形成されているので、ケース１の内壁で
形成される空間と内ケース２の内部空間とは孔部２ａに
より連通している。
【００１２】３方向圧電式加速度検出部３は、四角柱３
ａの４面、即ち４方向に圧電素子３ｂと錘３ｃを突出さ
せて取り付けてなる。３方向圧電式加速度検出部３は、
内ケースの底面に固定され、特許第２５８１９０１号公
報に記載のものと同一の構成であるので、３方向の加速
度を同時検出することが可能である。
【００１３】プリント基板４は、内ケース２の張り出し
部５に立設したスペーサ４ａにねじ止めされている。３
方向圧電式加速度検出部３とプリント基板４との間はリ
ード線（不図示）によって電気的に接続され、３方向圧
電式加速度検出部３の各方向の出力は、所定の処理回路
に入力される。
【００１４】この処理回路は、例えば、３方向圧電式加
速度検出部３が出力する３方向の加速度に応じた電荷信
号を電圧信号に変換するものである。また、処理回路の
アースラインは、内ケース２に接地すると共に地震計本
体（図示せず）のアースラインに接続されている。
【００１５】内ケース２に設けた４つの張り出し部５
は、内ケース２と３方向圧電式加速度検出部３で形成さ
れる空間の容積を縮小するためのもので、３方向圧電式
加速度検出部３と接触しないように配設されている。
【００１６】以上のように構成した３方向圧電式感震器
の作用について説明する。ケース１内部に内ケース２を
設けたので、ケース１内において空気と接触する表面積
は著しく増大する。また、内ケース２と３方向圧電式加
速度検出部３で形成される空間は、張り出し部５によっ
て著しく減少するので、ケース１内部に封入されている
空気の絶対量も減少することになる。
【００１７】このように、ケース１内部に封入される空
気の絶対量が少量となると共に、空気が接触するケース
１内部の表面積が著しく増大するので、ケース１外部の
気温が低下し、ケース１内部に結露が生じたとしても、
ケース１の内部に配置された各部材の単位表面積当たり
の結露する水分の量は減少する。これにより、圧電素子
表面の単位表面積当たりの結露する水分の量も減少する
ことになり、絶縁低下によるノイズの発生頻度を抑制す
ることができる。
【００１８】また、３方向圧電式感震器の処理回路のア
ースラインを内ケース２に接地すると共に地震計本体の
アースラインに接続し、最外ケースであるケース１と内
ケース２とを絶縁したことにより、この３方向圧電式感
震器とこの出力を処理する地震計本体とを離れた位置に
設置したとしても、３方向圧電式感震器と地震計本体間
に発生するグランドループノイズを低減できる。
【００１９】なお、上述の実施の形態においては、本発
明を３方向圧電式感震器に適用した場合について説明し
た。しかし、本発明は圧電素子を使用したものであれ
ば、その他の加速度検出部を備えるセンサ、例えば、単
軸加速度センサにも適用できる。
【００２０】また、上述の実施の形態においては、ケー
ス１内部の表面積を増大させるために内ケース２を設け
たが、内ケース２内に更にケースを設けて三重のケース
構造としてもよい。この場合、最も内側のケース内に、
加速度検出部３、プリント基板４を配設するようにし、
張り出し部５も最も内側のケース内に設けるようにす
る。
【００２１】更に、上述の実施の形態においては、ケー
ス１内部の空気と接触する表面積を増大させるために内
ケース２を設け、その形状をほぼ中空円筒形状とした場
合について説明した。しかし、本発明はこれに限らず、
加速度検出部３を包み込むような形状のものであればそ
の他の形状であってもよい。
【００２２】
【発明の効果】以上説明したように請求項１に係る発明
によれば、ケース内部に配設した内ケースより内ケース
の外側表面積及び内側表面積によって、ケース内部の空
気と接触する表面積を確実に増やすことができ、内ケー
スの内面に突出形成した張り出し部により中空円筒形状
の内ケースと四角柱の４面に圧電素子と錘を突出させて
取り付けてなる３方向圧電式加速度検出部３で形成され
る空間を縮小することができ、ケース内部の単位表面積
当たりに結露する水分の量が減少するので、結露による
絶縁低下を抑制でき、信頼性の向上が図れる。
【００２３】
【００２４】Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a piezoelectric acceleration sensor adapted to an environment in which temperature changes drastically. 2. Description of the Related Art Conventionally, there is a piezoelectric vibration sensor or the like as a piezoelectric acceleration sensor installed outdoors. As shown in FIG. 3, a piezoelectric vibration sensor of this type includes a printed circuit board 102 in which a piezoelectric acceleration detection unit 101 and an electric circuit for processing an output signal of the piezoelectric acceleration detection unit 101 are formed inside a case 100.
And so on. Here, the piezoelectric acceleration detector 101
Is capable of detecting acceleration in three directions with the same configuration as that described in Japanese Patent No. 2581901. [0003] However, in the conventional piezoelectric seismic device shown in FIG. 3, when it is installed in an environment where the temperature changes drastically, dew condensation occurs inside the case 100 and the piezoelectric type There are problems that the insulation of the piezoelectric element of the detection unit 101 is reduced, and that the printed circuit board 102 on which the electric circuit unit is formed is corroded. This is because if the insulation of the piezoelectric element is reduced, the S / N ratio of the piezoelectric acceleration detector 101 is reduced, which is not preferable as a seismic sensor for detecting weak vibration. [0004] The present invention has been made in view of such problems of the prior art, and an object of the present invention is to reduce the influence of dew condensation caused by a temperature change in an environment in which the apparatus is installed. Accordingly, it is intended to provide a highly reliable piezoelectric acceleration sensor. [0005] In order to solve the above-mentioned problems, the invention according to claim 1 is to provide a piezoelectric device in which four surfaces of a square prism are provided inside a case.
In a piezoelectric acceleration sensor having a three-direction piezoelectric acceleration detection unit in which an element and a weight are protruded and attached, an inner case having a hollow cylindrical shape is provided inside the case,
The three-way piezoelectric acceleration detector is fixed inside the inner case, and a projecting portion for reducing the space formed by the inner case and the three-direction piezoelectric acceleration detector is formed on the inner surface of the inner case. It was done. [0008] Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a partial longitudinal sectional view of the three-way piezoelectric seismic device according to the present invention, and FIG. 2 is a partial transverse sectional view of the three-way piezoelectric seismic device according to the present invention. A three-way piezoelectric seismic sensor according to the present invention is shown in FIG.
Alternatively, as shown in FIG. 2, the case 1 includes an inner case 2, a three-way piezoelectric acceleration detector 3, a printed circuit board 4 on which electronic components are mounted, a protrusion 5, a connector 6, and the like. The case 1 is formed by closely contacting an upper case member 1a and a lower case member 1b made of a metal member such as an aluminum alloy, thereby forming a completely closed case having a hollow cylindrical shape. The inner case 2 is made of a metal member such as an aluminum alloy, and is fixed to the bottom surface of the case 1 via an insulating member 2b in order to increase the surface area in contact with air inside the case 1. Further, since the hole 2a through which the lead wire passes is formed on the upper surface of the inner case 2, the space formed by the inner wall of the case 1 and the inner space of the inner case 2 communicate with each other by the hole 2a. The three-direction piezoelectric acceleration detecting section 3 has a rectangular prism 3
The piezoelectric element 3b and the weight 3c are mounted so as to protrude in four directions of a, that is, in four directions. The three-direction piezoelectric acceleration detector 3
Since it is fixed to the bottom surface of the inner case and has the same configuration as that described in Japanese Patent No. 2581901, accelerations in three directions can be simultaneously detected. The printed circuit board 4 is screwed to a spacer 4a erected on the projecting portion 5 of the inner case 2. 3
The directional piezoelectric acceleration detector 3 and the printed circuit board 4 are electrically connected by a lead wire (not shown), and outputs of each direction of the three-directional piezoelectric acceleration detector 3 are input to a predetermined processing circuit. You. This processing circuit converts, for example, a charge signal output from the three-directional piezoelectric acceleration detector 3 in accordance with three-directional acceleration into a voltage signal. The ground line of the processing circuit is grounded to the inner case 2 and connected to the ground line of the seismometer main body (not shown). Four overhang portions 5 provided on the inner case 2
Is for reducing the volume of the space formed by the inner case 2 and the three-directional piezoelectric acceleration detector 3, and is disposed so as not to contact the three-directional piezoelectric acceleration detector 3. The operation of the three-way piezoelectric vibrator thus constructed will be described. Since the inner case 2 is provided inside the case 1, the surface area of the case 1 that comes into contact with air is significantly increased. Further, since the space formed by the inner case 2 and the three-direction piezoelectric acceleration detector 3 is significantly reduced by the overhang 5, the absolute amount of air sealed in the case 1 is also reduced. As described above, the absolute amount of the air sealed in the case 1 becomes small, and the surface area inside the case 1 with which the air comes into contact is remarkably increased. Even if condensation forms inside,
The amount of condensed moisture per unit surface area of each member arranged inside the case 1 is reduced. As a result, the amount of water condensed per unit surface area of the piezoelectric element surface is also reduced, and the frequency of occurrence of noise due to a decrease in insulation can be suppressed. The ground line of the processing circuit of the three-way piezoelectric seismic sensor is grounded to the inner case 2 and connected to the ground line of the seismometer main body to insulate the outermost case 1 from the inner case 2. As a result, even if the three-way piezoelectric seismic sensor and the seismometer main body that processes this output are installed at separate positions, the ground loop noise generated between the three-way piezoelectric seismic sensor and the seismometer main body Can be reduced. In the above embodiment, a case has been described in which the present invention is applied to a three-way piezoelectric vibration sensor. However, the present invention can be applied to a sensor including another acceleration detecting unit, for example, a single-axis acceleration sensor as long as the sensor uses a piezoelectric element. In the above-described embodiment, the inner case 2 is provided in order to increase the surface area inside the case 1. However, a case may be further provided in the inner case 2 to form a triple case structure. In this case, in the innermost case,
The acceleration detection unit 3 and the printed circuit board 4 are provided,
The overhang portion 5 is also provided in the innermost case. Further, in the above-described embodiment, a case has been described where the inner case 2 is provided to increase the surface area of the case 1 which comes into contact with air, and the shape thereof is substantially a hollow cylindrical shape. However, the present invention is not limited to this,
Any other shape may be used as long as the shape encloses the acceleration detection unit 3. As described above, according to the first aspect of the present invention, the inner case is disposed within the case from the inner case.
Due to the outer surface area and inner surface area of the
The surface area that comes into contact with air can be reliably increased, and a hollow cylindrical shape is formed by an overhang that protrudes from the inner surface of the inner case.
The piezoelectric element and weight protrude from the inner case and the four surfaces of the square pillar
Formed by the attached three-way piezoelectric acceleration detector 3
Since the amount of water condensed per unit surface area inside the case can be reduced, insulation deterioration due to dew condensation can be suppressed, and reliability can be improved. [0024]
【図面の簡単な説明】
【図１】本発明に係る３方向圧電式感震器の部分縦断面
図
【図２】本発明に係る３方向圧電式感震器の部分横断面
図
【図３】従来の圧電式感震器の部分縦断面図
【符号の説明】
１…ケース、１ａ…上ケース部材、１ｂ…下ケース部
材、２…内ケース、２ａ…孔部、２ｂ…絶縁部材、３…
３方向圧電式加速度検出部、３ａ…四角柱、３ｂ…圧電
素子、３ｃ…錘、４…プリント基板、５…張り出し部。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial longitudinal sectional view of a three-way piezoelectric seismic device according to the present invention. FIG. 2 is a partial transverse sectional view of a three-way piezoelectric seismic device according to the present invention. DESCRIPTION OF SYMBOLS 1 ... case, 1a ... upper case member, 1b ... lower case member, 2 ... inner case, 2a ... hole, 2b ... insulating member, 3 …
Three-direction piezoelectric acceleration detector, 3a: square pole, 3b: piezoelectric element, 3c: weight, 4: printed circuit board, 5: overhanging part.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平１−195368（ＪＰ，Ａ) 特開 平７−280828（ＪＰ，Ａ) 特開 平６−231847（ＪＰ，Ａ) 特開 平３−105066（ＪＰ，Ａ) 特開 平９−211266（ＪＰ，Ａ) 実開 平１−61695（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01P 15/08 - 15/09 G01D 11/24 H05K 7/20 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-195368 (JP, A) JP-A-7-280828 (JP, A) JP-A-6-231847 (JP, A) JP-A-3- 105066 (JP, A) JP-A-9-211266 (JP, A) JP-A-1-61695 (JP, U) (58) Fields investigated (Int. Cl. 7 , DB name) G01P 15/08-15 / 09 G01D 11/24 H05K 7/20
Claims (1)
錘を突出させて取り付けてなる３方向圧電式加速度検出
部を有する圧電式加速度センサにおいて、前記ケース内
部に中空円筒形状の内ケースを配設すると共に、この内
ケースの内部に前記３方向圧電式加速度検出部を固定
し、前記内ケースと前記３方向圧電式加速度検出部とで
形成される空間を縮小する張り出し部を前記内ケースの
内面に突出形成したことを特徴とする圧電式加速度セン
サ。(57) [Claims] [Claim 1] A piezoelectric element is provided on four sides of a square pillar inside a case.
In a piezoelectric acceleration sensor having a three-directional piezoelectric acceleration detecting section having a weight protruded and attached , a hollow cylindrical inner case is provided inside the case, and the three-directional piezoelectric sensor is provided inside the inner case. A piezoelectric acceleration sensor, wherein an acceleration detecting portion is fixed, and a projecting portion for reducing a space formed by the inner case and the three-directional piezoelectric acceleration detecting portion is formed on an inner surface of the inner case.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21497498A JP3435065B2 (en) | 1998-07-30 | 1998-07-30 | Piezoelectric acceleration sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21497498A JP3435065B2 (en) | 1998-07-30 | 1998-07-30 | Piezoelectric acceleration sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000046861A JP2000046861A (en) | 2000-02-18 |
| JP3435065B2 true JP3435065B2 (en) | 2003-08-11 |
Family
ID=16664640
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21497498A Expired - Fee Related JP3435065B2 (en) | 1998-07-30 | 1998-07-30 | Piezoelectric acceleration sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3435065B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108731719A (en) * | 2017-04-20 | 2018-11-02 | 发那科株式会社 | Encoder |
-
1998
- 1998-07-30 JP JP21497498A patent/JP3435065B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108731719A (en) * | 2017-04-20 | 2018-11-02 | 发那科株式会社 | Encoder |
| US10267658B2 (en) | 2017-04-20 | 2019-04-23 | Fanuc Corporation | Encoder |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000046861A (en) | 2000-02-18 |
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