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JP2009042240A - Acceleration sensor - Google Patents

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Publication number
JP2009042240A
JP2009042240A JP2008253520A JP2008253520A JP2009042240A JP 2009042240 A JP2009042240 A JP 2009042240A JP 2008253520 A JP2008253520 A JP 2008253520A JP 2008253520 A JP2008253520 A JP 2008253520A JP 2009042240 A JP2009042240 A JP 2009042240A
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JP
Japan
Prior art keywords
vibrating
acceleration sensor
additional mass
base
vibrating arm
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.)
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Application number
JP2008253520A
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Japanese (ja)
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JP2009042240A5 (en
Inventor
Ryuta Nishizawa
竜太 西澤
Masako Tanaka
雅子 田中
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Seiko Epson Corp
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Seiko Epson Corp
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Priority to JP2008253520A priority Critical patent/JP2009042240A/en
Publication of JP2009042240A publication Critical patent/JP2009042240A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized acceleration sensor of high detection sensitivity. <P>SOLUTION: This acceleration sensor 1 is a vibratory body 10 having a base part 20 fixed on a base and a beam-shaped vibration arm 21 extended out of the base part 20 and bendingly vibrating in a planar direction at a prescribed resonance frequency. The vibration arm 21 includes: vibration arm parts 23 and 24 separated from each other by a through hole 22 bored therethrough at its width direction middle part, vertically to its thickness direction, and in its longitudinal direction; an additional mass part 25 together connecting end parts of the arm parts 23 and 24 separated from each other; and excitation electrodes 31 to 34 provided as excitation means on the arm parts 23 and 24. The vibration arm 21 is supported by a pseudo both-end fixation structure or a single-end fixation structure, having the base part 20 and the mass part 25, and used for detecting a change in the resonance frequency of the vibratory body 10 owing to an inertia effect of the mass part 25 when acceleration is given thereto. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、加速度が加えられたときに振動体の共振周波数が変化することを検出する加
速度センサに関する。
The present invention relates to an acceleration sensor that detects that the resonance frequency of a vibrating body changes when acceleration is applied.

従来、撓みばねと、共振子と、フレームに懸架された振動質量を有するシリコンからな
り、加速度が共振子の周波数の変化に基づき検出され、撓みばね及びフレーム及び振動質
量が、シリコン小板の構造化によって作成される加速度センサというものが知られている
(例えば、特許文献1参照)。
2. Description of the Related Art Conventionally, a bending spring, a resonator, and silicon having a vibrating mass suspended on a frame, acceleration is detected based on a change in the frequency of the resonator, and the bending spring, the frame, and the vibrating mass have a structure of a silicon plate. There is known an acceleration sensor created by conversion (see, for example, Patent Document 1).

また、シリコンウエハの基板上に一端が固定され、他方が変形可能な自由端を有するカ
ンチレバーと、カンチレバーの表面に形成された圧電素子膜と、圧電素子膜の表裏両面に
形成された金属電極と、カンチレバーの自由端に固定された重りとから構成される圧電振
動子を含む加速度センサが知られている(例えば、特許文献2参照)。
A cantilever having one end fixed on the substrate of the silicon wafer and the other having a deformable free end; a piezoelectric element film formed on the surface of the cantilever; and metal electrodes formed on both front and back surfaces of the piezoelectric element film; There is known an acceleration sensor including a piezoelectric vibrator composed of a weight fixed to a free end of a cantilever (see, for example, Patent Document 2).

また、板状の振動体と、振動体の両面に対向して形成される圧電素子と、振動体の一端
部を支持する支持手段を有し、振動体の一端部近傍に孔が形成され、振動体は長さ方向に
振動する(つまり、縦振動)。振動体の振動方向の加速度により振動体と圧電素子とが撓
み、この撓みにより圧電素子に発生する電圧を検出するという加速度センサも知られてい
る(例えば、特許文献3参照)。
In addition, a plate-shaped vibrating body, a piezoelectric element formed to face both surfaces of the vibrating body, and a supporting means for supporting one end of the vibrating body, a hole is formed near one end of the vibrating body, The vibrating body vibrates in the length direction (that is, longitudinal vibration). An acceleration sensor is also known in which a vibrating body and a piezoelectric element bend due to acceleration in the vibration direction of the vibrating body, and a voltage generated in the piezoelectric element due to this bending is detected (for example, see Patent Document 3).

さらに、加速度により移動可能な慣性体と、慣性体を支持し慣性体の移動時に変形する
支持梁と、支持梁上に設置された共振体を備え、共振体は励振部と振動状態を検知する受
信部と、振動を励振部から受信部に伝搬する伝搬部とからなり、加速度が印加された際、
支持梁の変形に対応した共振体の変形により生じる共振体の振動状態の変化を、励振部へ
の入力信号と受信部への出力信号により検出して印加された加速度を測定する加速度セン
サというものが知られている(例えば、特許文献4参照)。
Furthermore, an inertial body that can be moved by acceleration, a support beam that supports the inertial body and deforms when the inertial body moves, and a resonator that is installed on the support beam, the resonator detects the excitation unit and the vibration state. It consists of a receiving part and a propagation part that propagates vibration from the excitation part to the receiving part, and when acceleration is applied,
An acceleration sensor that measures the applied acceleration by detecting changes in the vibration state of the resonator caused by the deformation of the resonator corresponding to the deformation of the support beam from the input signal to the excitation unit and the output signal to the reception unit Is known (see, for example, Patent Document 4).

特開平6−43179号公報(第3頁、図1)JP-A-6-43179 (page 3, FIG. 1) 特開平2−248865号公報(第2、第3頁、図3,9)JP-A-2-248865 (second and third pages, FIGS. 3 and 9) 特開平8−146033号公報(第3頁、図1,2)JP-A-8-146033 (page 3, FIGS. 1 and 2) 特開平7−191052号公報(第1,2頁、図1)Japanese Patent Laid-Open No. 7-191052 (pages 1, 2 and 1)

上述した特許文献1では、加速度が加えられて撓みばねが撓むことにより生ずる共振子
の周波数変化量を検出している。また、検出感度を高めるために振動質量を付加している
。また、特許文献2においても、カンチレバーの先端部に重りを付加して検出感度を高め
ている。そして、これら振動質量や重りは、加速度が加えられる方向に備えられているの
で、振動体を振動するために必要とされるエネルギーが大きくなるとともに、耐衝撃性が
低下することが考えられる。
また、加速度センサの小型化が困難となるという課題がある。
In Patent Document 1 described above, the amount of change in the frequency of the resonator that occurs when the flexure spring is deflected by applying acceleration is detected. In addition, a vibrating mass is added to increase detection sensitivity. Also in Patent Document 2, the detection sensitivity is increased by adding a weight to the tip of the cantilever. And since these vibration masses and weights are provided in the direction in which acceleration is applied, it is considered that the energy required to vibrate the vibrating body increases and the impact resistance decreases.
In addition, there is a problem that it is difficult to reduce the size of the acceleration sensor.

また、特許文献3では、振動体の縦振動を用いており、縦振動の場合は周波数の変化量
が屈曲振動に比べ極めて小さく、検出感度を高めることが難しい。また、振動体の支持構
造が複雑になることと、そのために振動漏れが発生し易いという課題がある。
In Patent Document 3, longitudinal vibration of a vibrating body is used. In the case of longitudinal vibration, the amount of change in frequency is extremely small compared to bending vibration, and it is difficult to increase detection sensitivity. In addition, there is a problem that the support structure of the vibrating body is complicated and vibration leakage is likely to occur.

さらに、振動体の一端部近傍に孔が設けられており、この孔の周縁部に応力集中が発生
し易い構造のため、耐衝撃性が低下するという課題もある。
Furthermore, since a hole is provided in the vicinity of one end portion of the vibrating body and stress concentration tends to occur at the peripheral portion of the hole, there is a problem that impact resistance is reduced.

また、特許文献4による加速度センサは、支持梁に発生する変形を、支持梁に接合され
た共振体により検出するという構造である。支持梁と共振体とは異種材料からなり構成す
る材質の熱膨張率が異なるため、温度変化による支持梁または共振体の変形差が生じ、こ
れが周波数変化として出力されてしまうため、温度特性が悪いという課題を有している。
Further, the acceleration sensor according to Patent Document 4 has a structure in which deformation generated in the support beam is detected by a resonator bonded to the support beam. The support beam and the resonator are made of different materials and have different coefficients of thermal expansion. Therefore, a difference in deformation of the support beam or the resonator due to a temperature change occurs, which is output as a frequency change, resulting in poor temperature characteristics. It has a problem.

また、支持梁と共振体とは接合されているため、接合部において加速度による力の伝搬
ロスが生じるとともに、接合部における長期的な信頼性を確保しにくいという課題もある
In addition, since the support beam and the resonator are joined, there is a problem that a force propagation loss due to acceleration occurs at the joint, and it is difficult to ensure long-term reliability at the joint.

さらに、正確な加速度検出には、支持梁に対する共振体の位置精度が要求されるが、支
持梁と共振体とが別部材であることから、位置精度をだしにくいので製造コストが増加し
、小型化も困難であると予測される。
In addition, accurate acceleration detection requires the position accuracy of the resonator relative to the support beam, but the support beam and the resonator are separate members, which makes it difficult to achieve position accuracy, increasing manufacturing costs, and reducing the size. It is predicted that it will be difficult.

本発明は、上述の課題の少なくとも一部を解決するためになされたものであり、以下の
形態または適用例として実現することが可能である。
SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[適用例1]本適用例の加速度センサは、基台に固定する基部と、前記基部から延出さ
れ所定の共振周波数にて平面方向に屈曲振動をする梁状の振動腕と、からなる振動体であ
って、前記振動腕が、幅方向中央部に厚さ方向に垂直に、且つ長手方向に開設される貫通
孔によって分割された振動腕部と、分割された前記振動腕部の先端部を連結する付加質量
部と、前記振動腕部に設けられる励振手段と、を備え、前記振動腕が、前記基部と前記付
加質量部とにより擬似両端固定構造または片端固定構造で支持され、加速度が加えられた
ときの前記付加質量部の慣性効果による前記振動体の共振周波数変化を検出することを特
徴とする。
[Application Example 1] An acceleration sensor according to this application example includes a base portion fixed to a base and a beam-like vibrating arm extending from the base portion and bending-vibrating in a plane direction at a predetermined resonance frequency. The vibrating arm is divided by a through-hole that is formed in the center in the width direction perpendicular to the thickness direction and in the longitudinal direction, and the distal end portion of the divided vibrating arm portion And an excitation means provided on the vibrating arm, and the vibrating arm is supported by the base and the additional mass in a pseudo double-end fixed structure or a single-end fixed structure, and an acceleration is provided. A change in the resonance frequency of the vibrating body due to the inertial effect of the additional mass when added is detected.

なお、擬似両端固定構造とは、例えば、振動体の基部が固定端で、振動腕の先端部(付
加質量部に相当する部分)は自由端ではあるが、付加質量部が大きいため先端部がほとん
ど振動しないような固定構造を意味する。
The pseudo-both-end fixed structure is, for example, that the base of the vibrating body is a fixed end and the tip of the vibrating arm (the portion corresponding to the additional mass) is a free end, but the tip is not large because the additional mass is large. It means a fixed structure that hardly vibrates.

本適用例によれば、加速度が加えられたときに付加質量部の慣性効果により、振動腕に
伸縮応力(引っ張り応力と圧縮応力)が発生することで振動体の共振周波数が変化するこ
とを利用して加速度を検出するものである。具体的には、振動腕に引っ張り応力が発生す
るときには共振周波数は高くなり、振動腕に圧縮応力が発生するときには共振周波数が低
くなる。この振動体は片端固定構造の屈曲振動のため、加速度が加えられることによる共
振周波数変化量が前述した従来技術の縦振動よりも大きくなり、高い検出感度の加速度セ
ンサを実現できる。
According to this application example, when the acceleration is applied, the resonance effect of the vibrating body is changed by the expansion and contraction stress (tensile stress and compressive stress) generated in the vibrating arm due to the inertial effect of the additional mass part. Thus, the acceleration is detected. Specifically, when a tensile stress is generated in the vibrating arm, the resonance frequency is high, and when a compressive stress is generated in the vibrating arm, the resonance frequency is low. Since this vibrating body is a flexural vibration of a one-end fixed structure, the amount of change in the resonance frequency due to the application of acceleration becomes larger than the longitudinal vibration of the prior art described above, and an acceleration sensor with high detection sensitivity can be realized.

また、振動腕の長手方向に貫通孔が設けられることにより、振動腕部は断面積が小さく
なり、側面に設けられる励振電極間の距離が小さいため電界効率が高く、その結果消費電
流を低く抑えることができる。
In addition, since the through-hole is provided in the longitudinal direction of the vibrating arm, the cross-sectional area of the vibrating arm is reduced, and the electric field efficiency is high because the distance between the excitation electrodes provided on the side surfaces is small, resulting in low current consumption. be able to.

また、振動腕は貫通孔により断面積が小さい2本の振動腕部に分割される。従って、加
速度が加えられた際の屈曲部に発生する伸縮応力が大きくなり、共振周波数の変化量がよ
り大きくなることから検出感度を高めることができる。
Further, the vibrating arm is divided into two vibrating arm portions having a small cross-sectional area by the through hole. Therefore, the expansion and contraction stress generated in the bent portion when acceleration is applied increases, and the amount of change in the resonance frequency increases, so that the detection sensitivity can be increased.

さらに、本適用例による加速度センサは、振動腕に発生する伸縮応力による共振周波数
変化を検出する構造のため、仮に振動体をパッケージングする際において、加速度による
振動腕の長さ方向の伸縮は非常に小さく、振動腕が屈曲振動をする範囲のスペースがあれ
ばよく、小型化できるという効果を有する。
Furthermore, since the acceleration sensor according to this application example has a structure that detects a change in the resonance frequency due to the stretching stress generated in the vibrating arm, when the vibrating body is packaged, the length of the vibrating arm in the longitudinal direction due to the acceleration is extremely low. It is sufficient if there is a space in a range where the vibrating arm is flexibly vibrated, and the size can be reduced.

また、本適用例による加速度センサは基部と振動腕とが一体で形成されているため、前
述した従来技術(特許文献4)による支持梁と共振体とを別体で構成し接合する構造のよ
うに、それぞれの熱膨張率が異なることから生じる温度変化による支持梁または共振体の
変形差が周波数変化として出力されてしまうことがなく、温度特性がよい加速度センサを
実現できる。
In addition, since the acceleration sensor according to this application example has the base portion and the vibrating arm integrally formed, the support beam and the resonator according to the above-described prior art (Patent Document 4) are configured separately and joined. In addition, the deformation difference of the support beam or the resonator due to the temperature change caused by the difference in thermal expansion coefficient is not output as a frequency change, and an acceleration sensor with good temperature characteristics can be realized.

また、従来技術のような支持梁と共振体とを接合する構造に比べ接合部がないため、接
合部における加速度により発生する力の伝搬ロスが生じることもなく、さらに、長期的な
信頼性を確保できるという効果がある。
さらに、基部と振動腕とが一体でかつ同一平面内に形成されていることから、厚さ方向
への突出部が存在せず薄型化を実現できる。
In addition, since there is no joint compared to the structure in which the support beam and the resonator are joined as in the prior art, there is no loss of force propagation caused by acceleration at the joint, and long-term reliability is achieved. There is an effect that it can be secured.
Furthermore, since the base portion and the vibrating arm are integrally formed in the same plane, there is no projecting portion in the thickness direction, and a reduction in thickness can be realized.

[適用例2]上記適用例に記載の加速度センサであって、前記基部と、前記振動腕と、
前記付加質量部と、からなる振動体が2組設けられ、2組の前記付加質量部を共通付加質
量部とし、前記共通付加質量部の重心位置に対して点対称となるように2組の前記振動体
が直線状に連結されていることが好ましい。
Application Example 2 In the acceleration sensor according to the application example, the base, the vibrating arm,
Two sets of vibrating bodies including the additional mass portion are provided, and the two sets of additional mass portions are common additional mass portions, and two sets of the additional mass portions are symmetrical with respect to the center of gravity of the common additional mass portion. It is preferable that the vibrating bodies are connected linearly.

このような構造によれば、付加質量部を挟んで対向する一対の振動体を有する構造体が
構成される。この際、それぞれ対向する振動腕は、付加質量部が十分大きな質量を有して
いるため、互いに逆位相の高次の屈曲振動モードを有し、振動バランスがよい振動体を構
成することができる。つまり高いQ値が得られる。
According to such a structure, a structure having a pair of vibrating bodies facing each other with the additional mass portion interposed therebetween is configured. At this time, each of the vibrating arms facing each other has a sufficiently large mass, so that a vibrating body having a high-order bending vibration mode having an opposite phase to each other and having a good vibration balance can be formed. . That is, a high Q value is obtained.

また、加速度が加えられたとき、隣り合う振動腕部の一方の振動腕部には圧縮応力が発
生し、他方の振動腕部には引っ張り応力が発生する。このような構造の場合、両振動体の
共振周波数の差動をとることで周波数温度特性の影響を打ち消すことができるという効果
がある。
Further, when acceleration is applied, compressive stress is generated in one vibrating arm portion of adjacent vibrating arm portions, and tensile stress is generated in the other vibrating arm portion. In the case of such a structure, there is an effect that the influence of the frequency temperature characteristic can be canceled by taking the difference between the resonance frequencies of both vibrators.

[適用例3]本適用例に記載の加速度センサは、基台に固定する基部と、前記基部から
平行に延出され所定の共振周波数にて平面方向に屈曲振動をする梁状の複数の振動腕と、
からなる振動体であって、複数の前記振動腕それぞれの幅方向中央部に振動方向に対して
垂直に、且つ長手方向に開設される少なくとも一つの貫通孔と複数の前記振動腕の先端部
を連結する付加質量部と、複数の前記振動腕それぞれの両側側面と、前記貫通孔内部側面
とに設けられる励振電極と、を備え、加速度が加えられたときの前記付加質量部の慣性効
果による前記振動体の共振周波数変化を検出することを特徴とする。
Application Example 3 The acceleration sensor according to this application example includes a base fixed to a base and a plurality of beam-like vibrations extending in parallel from the base and bending-vibrated in a plane direction at a predetermined resonance frequency. Arms,
Each of the plurality of vibrating arms has at least one through-hole formed perpendicularly to the vibration direction and in the longitudinal direction at the center in the width direction of each of the plurality of vibrating arms, and tip portions of the plurality of vibrating arms. An additional mass part to be connected, excitation electrodes provided on both side surfaces of each of the plurality of vibrating arms and the inner side surface of the through hole, and the inertial effect of the additional mass part when acceleration is applied It is characterized by detecting a change in the resonance frequency of the vibrating body.

このように構成される加速度センサは、付加質量部で先端部が連結された複数の振動腕
に貫通孔を設けている。従って、振動腕の断面積が小さくなり、加速度を加えたときの振
動腕の変位量を大きくとれることから検出感度を高めることができる。
さらに、振動腕の両側側面と貫通孔の内側側面に励振電極を設けているので、励振電極
間の距離が短くなり電界効率が高まる。このことから低消費電力化が可能となるという効
果がある。
In the acceleration sensor configured as described above, through holes are provided in a plurality of vibrating arms having tip portions connected by additional mass portions. Therefore, since the cross-sectional area of the vibrating arm is reduced and the displacement amount of the vibrating arm when acceleration is applied can be increased, the detection sensitivity can be increased.
Furthermore, since the excitation electrodes are provided on both side surfaces of the vibrating arm and the inner side surface of the through hole, the distance between the excitation electrodes is shortened and the electric field efficiency is increased. This has the effect of reducing power consumption.

[適用例4]適用例3に記載の加速度センサであって、前記貫通孔が、少なくとも複数
の前記振動腕と前記基部との連結部近傍に設けられていることが好ましい。
Application Example 4 In the acceleration sensor according to Application Example 3, it is preferable that the through hole is provided in the vicinity of a connection portion between at least the plurality of vibrating arms and the base portion.

振動腕と基部との連結部近傍は、屈曲振動において歪みが最も大きい位置である。従っ
て、このような歪みが大きい位置に貫通孔を設け、振動腕の両側側面と貫通孔の内側側面
に励振電極を設けることにより励振電極間の距離が短くなり、電界効率を高めることがで
き、低消費電力化を実現できる。
The vicinity of the connecting portion between the vibrating arm and the base is a position where the distortion is the largest in bending vibration. Therefore, by providing a through hole at a position where such distortion is large and providing excitation electrodes on both side surfaces of the vibrating arm and the inner side surface of the through hole, the distance between the excitation electrodes is shortened, and the electric field efficiency can be increased. Low power consumption can be realized.

[適用例5]適用例3に記載の加速度センサであって、前記貫通孔が、複数の前記振動
腕に前記基部との連結部近傍と、前記付加質量部との連結部近傍と、長手方向中央部と、
に開設されていることが好ましい。
[Application Example 5] The acceleration sensor according to Application Example 3, wherein the through hole has a plurality of vibrating arms in the vicinity of a connection part with the base, a connection part with the additional mass part, and a longitudinal direction. The central part,
It is preferable to be established in

このようにすれば、屈曲振動において歪みが最も大きい位置と、振動腕の中央部及び先
端部に貫通孔を有し、励振電極を設けることにより、一層電界効率を高めることができ、
低消費電力化を実現できる。
In this way, the electric field efficiency can be further improved by providing the position where the distortion is greatest in the bending vibration, the through hole in the center part and the tip part of the vibrating arm, and providing the excitation electrode.
Low power consumption can be realized.

[適用例6]適用例3に記載の加速度センサであって、前記基部と、前記貫通孔が開設
された複数の前記振動腕と、前記付加質量部とからなる振動体が2組設けられ、2組の前
記付加質量部を共通付加質量部とし、前記共通付加質量部の重心位置に対して点対称とな
るように2組の前記振動体が直線状に連結されていることが好ましい。
[Application Example 6] The acceleration sensor according to Application Example 3, wherein two sets of vibration bodies each including the base portion, the plurality of vibrating arms in which the through holes are opened, and the additional mass portion are provided, It is preferable that two sets of the additional mass portions are common additional mass portions, and the two sets of the vibrating bodies are linearly connected so as to be point-symmetric with respect to the position of the center of gravity of the common additional mass portion.

このようにすれば、付加質量部を挟んで対向する一対の湾曲された振動腕からなる振動
体を有する両端固定構造の振動体が構成されることになる。この際、それぞれ対向する振
動腕は、逆位相の高次の屈曲振動モードを有し、振動バランスがよい振動体を構成するこ
とができる。つまり高いQ値が得られる。
In this way, a vibrating body having a both-ends fixed structure having a vibrating body composed of a pair of curved vibrating arms facing each other with the additional mass portion interposed therebetween is configured. At this time, the vibrating arms facing each other can form a vibrating body having an antiphase high-order bending vibration mode and a good vibration balance. That is, a high Q value is obtained.

[適用例7]上記適用例に記載の加速度センサであって、前記振動体が水晶からなるこ
とが好ましい。
Application Example 7 In the acceleration sensor according to the application example described above, it is preferable that the vibrator is made of quartz.

振動体の材質としては、圧電性を有する材料であれば特に限定されないが、水晶にすれ
ば、周波数温度特性がよいこと、貫通孔を含めてフォトリソグラフィ技術により一体形成
が容易であり製造し易く、高精度で形成することができる。
The material of the vibrating body is not particularly limited as long as it is a piezoelectric material, but if it is made of quartz, it has good frequency-temperature characteristics, and can be easily formed integrally by photolithography technology, including through-holes. Can be formed with high accuracy.

[適用8]上記適用例に記載の加速度センサであって、前記振動体が恒弾性材料からな
り、前記振動腕の側面に圧電素子膜が形成されていることが好ましい。
[Application 8] In the acceleration sensor according to the application example described above, it is preferable that the vibrating body is made of a constant elastic material, and a piezoelectric element film is formed on a side surface of the vibrating arm.

恒弾性材料としては、例えば、ニッケル、鉄、クロム、チタン、あるいはそれらの合金
であるエリンバ、鉄−ニッケル合金などが含まれる。
このように、振動体として恒弾性材料を用いることにより構造的強度が高まり、強い加
速度領域の検出に対応できるという効果がある。
The constant elastic material includes, for example, nickel, iron, chromium, titanium, or an elimba or an iron-nickel alloy thereof.
As described above, the use of a constant elastic material as the vibrator increases the structural strength and has an effect of being able to cope with detection of a strong acceleration region.

以下、本発明の実施形態を図面に基づいて説明する。
図1〜図5は実施形態1に係る加速度センサを示し、図6は実施形態2、図7は実施形
態3、図8は実施形態4、図9は実施形態5、図10は実施形態6、図11は実施形態7
を示している。
なお、以下の説明で参照する図は、図示の便宜上、部材ないし部分の縦横の縮尺は実際
のものとは異なる模式図である。
(実施形態1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 5 show an acceleration sensor according to Embodiment 1, FIG. 6 shows Embodiment 2, FIG. 7 shows Embodiment 3, FIG. 8 shows Embodiment 4, FIG. 9 shows Embodiment 5, and FIG. FIG. 11 shows the seventh embodiment.
Is shown.
Note that the drawings referred to in the following description are schematic views in which the vertical and horizontal scales of members or portions are different from actual ones for convenience of illustration.
(Embodiment 1)

図1は、実施形態1に係る加速度センサの1例を示し、(a)は正面図、(b)は(a
)のH−H切断面を示す断面図である。図1(a)において、加速度センサ1は、基台(
図示せず)に固定する基部20と、基部20の端面から延出され所定の共振周波数にて平
面方向に屈曲振動をする梁状の振動腕21と、を有する振動体10により構成される。
FIG. 1 shows an example of an acceleration sensor according to the first embodiment, where (a) is a front view and (b) is (a
It is sectional drawing which shows the HH cut surface of FIG. In FIG. 1 (a), the acceleration sensor 1 has a base (
The vibrating body 10 includes a base 20 that is fixed to the base 20 and a beam-like vibrating arm 21 that extends from an end face of the base 20 and flexurally vibrates in a plane direction at a predetermined resonance frequency.

振動体10は圧電性材料により形成されている。圧電性材料としては、チタン酸鉛(P
bTiO3)、チタン酸ジルコン酸鉛(PZT(登録商標))、酸化亜鉛(ZnO)、水
晶等を使用することができるが、本実施形態では、周波数温度特性が優れ、高いQ値を有
する水晶を使用した場合を例示して説明する。
The vibrating body 10 is made of a piezoelectric material. As a piezoelectric material, lead titanate (P
bTiO 3 ), lead zirconate titanate (PZT (registered trademark)), zinc oxide (ZnO), quartz, and the like can be used. In this embodiment, however, the quartz has excellent frequency-temperature characteristics and a high Q value. The case where is used will be described as an example.

振動体10は、XY平面に展開されたZ板であって、基部20の一辺の中央からY軸方
向に単純梁状の振動腕21が延出されて構成されている。基部20は、振動体10を図示
しないパッケージの基台に固定するための固定部である。振動腕21の幅方向(X軸方向
)中央部には、振動腕21の振動方向に対して垂直、つまり厚さ方向(Z軸方向)に貫通
し、且つ、長手方向(Y軸方向)に沿って貫通孔22が開設されている。
The vibrating body 10 is a Z plate developed on the XY plane, and is configured by extending a simple beam-like vibrating arm 21 from the center of one side of the base 20 in the Y-axis direction. The base 20 is a fixing part for fixing the vibrating body 10 to a base of a package (not shown). The central portion of the vibrating arm 21 in the width direction (X-axis direction) is perpendicular to the vibrating direction of the vibrating arm 21, that is, penetrates in the thickness direction (Z-axis direction) and extends in the longitudinal direction (Y-axis direction). A through-hole 22 is opened along.

振動腕21の先端部(自由端)には、付加質量部25が形成されている。付加質量部2
5は、本実施形態では、基部20と同等な質量または、さらに大きな質量となるように平
面サイズが設定されている。また、貫通孔22の一方の端部は基部20との連結部まで達
し、他方の端部は付加質量部25との連結部まで達している。
なお、付加質量部25の大きさは、上述した擬似両端固定構造となる範囲で任意の大き
さに設定することができる。
An additional mass portion 25 is formed at the tip (free end) of the vibrating arm 21. Additional mass part 2
In this embodiment, the plane size is set so that the mass is equal to or larger than the base 20 in this embodiment. Further, one end portion of the through hole 22 reaches the connecting portion with the base portion 20, and the other end portion reaches the connecting portion with the additional mass portion 25.
In addition, the magnitude | size of the additional mass part 25 can be set to arbitrary magnitude | sizes in the range used as the pseudo | simulation both-ends fixing structure mentioned above.

振動腕21は、貫通孔22により振動腕部23と振動腕部24とに分割され、先端部は
付加質量部25によって連結されている。振動腕部23,24は、振動腕21の中心軸P
に対して対称形である。これら振動腕部23,24それぞれの側面には励振電極が形成さ
れている。
The vibrating arm 21 is divided into a vibrating arm portion 23 and a vibrating arm portion 24 by a through-hole 22, and the distal end portion is connected by an additional mass portion 25. The vibrating arm portions 23, 24 are center axes P of the vibrating arm 21.
Is symmetrical. Excitation electrodes are formed on the side surfaces of the vibrating arm portions 23 and 24, respectively.

次に、図1(b)を参照して励振手段としての励振電極の構成について説明する。振動
腕部23の外側面23aには励振電極31、内側面23bには励振電極33が形成されて
いる。また、振動腕部24の外側面24aには励振電極32、内側面24bには励振電極
34が形成されている。励振電極31〜34は、貫通孔22の概ねY軸方向側面の範囲全
体に形成される。なお、励振電極31〜34は検出電極を兼用する。
Next, the configuration of the excitation electrode as the excitation means will be described with reference to FIG. An excitation electrode 31 is formed on the outer side surface 23a of the vibrating arm 23, and an excitation electrode 33 is formed on the inner side surface 23b. An excitation electrode 32 is formed on the outer surface 24a of the vibrating arm 24, and an excitation electrode 34 is formed on the inner surface 24b. Excitation electrodes 31-34 are formed in the whole range of the side surface of through-hole 22 in the Y-axis direction. The excitation electrodes 31 to 34 also serve as detection electrodes.

励振電極31,32は同電位の電極であり、励振電極33,34は励振電極31,32
とは異なる電位の電極であり、図示しないが、それぞれが基部20の表面まで延在され、
図示しない発振回路及び検出回路に接続される。
The excitation electrodes 31 and 32 are electrodes having the same potential, and the excitation electrodes 33 and 34 are excitation electrodes 31 and 32.
Are electrodes having different potentials, and although not shown, each extends to the surface of the base 20,
It is connected to an oscillation circuit and a detection circuit (not shown).

発振回路から励振電極31,32、励振電極33,34それぞれに逆電位の励振信号が
入力されると、振動腕21は、基部20との連結部近傍を振動の節として一次の屈曲振動
をしようとすると、付加質量部25が大きいため、図1(a)に表すような二次の屈曲振
動で共振する。
When excitation signals having opposite potentials are input to the excitation electrodes 31 and 32 and the excitation electrodes 33 and 34 from the oscillation circuit, the resonating arm 21 will perform primary bending vibration with the vicinity of the connecting portion with the base 20 as a vibration node. Then, since the additional mass part 25 is large, it resonates by secondary bending vibration as shown in FIG.

つまり、振動腕21に励振信号が入力されると、付加質量部25の先端部が矢印C方向
に振動しようとするが大きな付加質量部25が存在するため、その移動量はごくわずかで
あり振動腕21は、二点鎖線C’で示すような二次の屈曲振動となる。
That is, when an excitation signal is input to the vibrating arm 21, the tip of the additional mass portion 25 tries to vibrate in the direction of arrow C, but there is a large additional mass portion 25, so that the amount of movement is very small and vibration occurs. The arm 21 exhibits a secondary bending vibration as indicated by a two-dot chain line C ′.

また、同様に、付加質量部25の先端部が矢印B方向に振動しようとするとき、付加質
量部25が存在するため、その移動量はごくわずかであり振動腕21は、破線B’で示す
ような二次の屈曲振動となる。
Similarly, when the tip of the additional mass portion 25 tries to vibrate in the direction of the arrow B, the additional mass portion 25 exists, so that the amount of movement is very small, and the vibrating arm 21 is indicated by a broken line B ′. Such secondary bending vibration occurs.

従って、このような振動体10は基部を固定部とする片端固定構造ではあるが、付加質
量部25を基部20と同等か、さらに大きな質量とすることにより、付加質量部25と基
部20との間であたかも擬似両端固定構造が構成されているといえる。そのことから振動
腕21は、振動腕21と基部20との連結部近傍と、振動腕21と付加質量部25との連
結部近傍と、に振動の節を有する高次の屈曲振動モードとなる。
Therefore, although such a vibrating body 10 has a one-end fixed structure in which the base portion is a fixed portion, by making the additional mass portion 25 equal to or larger than the base portion 20, It can be said that a pseudo-both-end fixing structure is formed between the two. Therefore, the vibrating arm 21 becomes a higher-order flexural vibration mode having vibration nodes in the vicinity of the connecting portion between the vibrating arm 21 and the base portion 20 and in the vicinity of the connecting portion between the vibrating arm 21 and the additional mass portion 25. .

次に、加速度検出について説明する。
図1(a)において、振動腕21がX軸方向に所定の共振周波数で二次の屈曲振動して
いるときに、+Y軸方向の加速度+Ayが加えられると、振動腕21の基部20との連結
部及び屈曲部には付加質量部25の慣性効果により圧縮応力が発生する。圧縮応力が発生
すると共振周波数は低くなる方向に変化する。また、−Y軸方向に加速度−Ayが加えら
れると、振動腕21の基部20との連結部及び屈曲部には引っ張り応力が発生する。引っ
張り応力が発生すると共振周波数は高くなる方向に変化する。
Next, acceleration detection will be described.
In FIG. 1A, when acceleration + Ay in the + Y-axis direction is applied when the vibrating arm 21 is subjected to secondary bending vibration at a predetermined resonance frequency in the X-axis direction, A compressive stress is generated in the connecting portion and the bent portion due to the inertia effect of the additional mass portion 25. When compressive stress is generated, the resonance frequency changes in the direction of lowering. Further, when the acceleration −Ay is applied in the −Y-axis direction, tensile stress is generated in the connecting portion and the bent portion of the vibrating arm 21 with the base portion 20. When a tensile stress is generated, the resonance frequency changes in a higher direction.

この共振周波数変化を検出回路にて検出し、検出された共振周波数を変換回路(図示せ
ず)で電圧に変換し、加速度として検出することができる。
なお、共振周波数を位相速度としてとらえ、位相速度の変化値を微分回路にて時間で微
分して加速度とする構成としてもよい。
This change in resonance frequency can be detected by a detection circuit, and the detected resonance frequency can be converted into a voltage by a conversion circuit (not shown) and detected as an acceleration.
The resonance frequency may be regarded as the phase velocity, and the change value of the phase velocity may be differentiated with respect to time by a differentiation circuit to obtain acceleration.

従って、上述した実施形態1によれば、加速度が加えられたときに付加質量部25の慣
性効果により、振動腕21に伸縮応力(引っ張り応力と圧縮応力)が発生することによる
振動体10の共振周波数が変化することを利用して加速度を検出するものである。具体的
には、振動腕21に引っ張り応力が発生するときには共振周波数は高くなり、振動腕21
に圧縮応力が発生するときには共振周波数が低くなる。従って、この振動体10によれば
、加速度が加えられることによる共振周波数変化量が前述した従来技術の縦振動よりも大
きくなり、高い検出感度の加速度センサを実現できる。
Therefore, according to the first embodiment described above, the resonance of the vibrating body 10 due to the expansion and contraction stress (tensile stress and compression stress) generated in the vibrating arm 21 due to the inertial effect of the additional mass portion 25 when acceleration is applied. The acceleration is detected by utilizing the change in frequency. Specifically, when a tensile stress is generated in the vibrating arm 21, the resonance frequency increases, and the vibrating arm 21
When compressive stress is generated, the resonance frequency is lowered. Therefore, according to the vibrating body 10, the amount of change in the resonance frequency due to the application of acceleration is larger than the longitudinal vibration of the conventional technology described above, and an acceleration sensor with high detection sensitivity can be realized.

また、振動腕21の長手方向に貫通孔22が設けられることにより、振動腕部23,2
4の断面積が小さくなり、側面に設けられる励振電極間の距離が小さくなるため電界効率
が高く、その結果消費電流を低く抑えることができる。
Further, by providing the through-hole 22 in the longitudinal direction of the vibrating arm 21, the vibrating arm portions 23, 2 are provided.
Since the sectional area of 4 is reduced and the distance between the excitation electrodes provided on the side surfaces is reduced, the electric field efficiency is high, and as a result, the current consumption can be kept low.

また、振動腕21は貫通孔22により断面積が小さい2本の振動腕部23,24に分割
される。従って、加速度が加えられた際の屈曲部に発生する伸縮応力が大きくなり、共振
周波数の変化量がより大きくなることから検出感度を高めることができる。
The vibrating arm 21 is divided into two vibrating arm portions 23 and 24 having a small cross-sectional area by the through hole 22. Therefore, the expansion and contraction stress generated in the bent portion when acceleration is applied increases, and the amount of change in the resonance frequency increases, so that the detection sensitivity can be increased.

また、付加質量部25を振動腕に対して充分に大きくすることで、振動腕21の先端部
の移動量は極めて小さい。従って、振動腕21は、付加質量部25と基部20との間で擬
似両端固定構造が構成されることから高次の屈曲振動モードとなる。このような高次の屈
曲振動モードにおいて、検出感度がよい加速度センサを実現できる。
Further, by making the additional mass portion 25 sufficiently large with respect to the vibrating arm, the moving amount of the tip portion of the vibrating arm 21 is extremely small. Therefore, the vibrating arm 21 is in a higher-order bending vibration mode because the pseudo both-ends fixing structure is configured between the additional mass portion 25 and the base portion 20. In such a higher-order bending vibration mode, an acceleration sensor with good detection sensitivity can be realized.

さらに、本実施形態による加速度センサ1は、振動腕21に発生する伸縮応力による共
振周波数変化を検出する構造である。従って、大きな質量を有する付加質量部25を設け
ることにより、加速度が加えられた際の屈曲部に発生する引っ張り応力または圧縮応力が
大きくなることから検出感度を高めることができる。
Furthermore, the acceleration sensor 1 according to the present embodiment has a structure that detects a change in resonance frequency due to stretching stress generated in the vibrating arm 21. Therefore, by providing the additional mass portion 25 having a large mass, the detection sensitivity can be increased because the tensile stress or the compressive stress generated in the bent portion when acceleration is applied is increased.

なお、付加質量部25の大きさは、上述した擬似両端支持構造となる範囲で任意の大き
さに設定することができる。振動体10をパッケージングする際において、加速度による
振動腕21の長さ方向の伸縮は非常に小さく、振動腕21が屈曲振動をする範囲のスペー
スがあればよく、小型化できるという効果を有する。
In addition, the magnitude | size of the additional mass part 25 can be set to arbitrary magnitude | sizes in the range used as the pseudo | simulated both-ends support structure mentioned above. When the vibrating body 10 is packaged, expansion and contraction in the length direction of the vibrating arm 21 due to acceleration is very small, and it is sufficient if there is a space in a range where the vibrating arm 21 performs flexural vibration, and the size can be reduced.

また、基部20と振動腕21とが一体で形成されているため、前述した従来技術(特許
文献4)による支持梁と共振体とを別体で構成し接合する構造のように、それぞれの熱膨
張率が異なることから生じる温度変化による支持梁または共振体の変形差が周波数変化と
して出力されてしまうことがなく、温度特性がよい加速度センサを実現できる。
In addition, since the base 20 and the vibrating arm 21 are integrally formed, each of the heat beams as in the structure in which the supporting beam and the resonator according to the above-described prior art (Patent Document 4) are configured separately and joined. An acceleration sensor with good temperature characteristics can be realized without the deformation difference of the support beam or the resonator due to the temperature change caused by different expansion coefficients being output as a frequency change.

また、従来技術のような支持梁と共振体とを接合する構造に比べ接合部がないため、接
合部における加速度により発生する力の伝搬ロスが生じることもなく、さらに、長期的な
信頼性を確保できるという効果がある。
さらに、振動体10の材質を水晶とし、基部20と振動腕21とが一体でかつ同一平面
内に形成することから、周波数温度特性がよく、貫通孔22を含めてフォトリソグラフィ
技術により一体形成が容易であり製造し易く、高精度で形成することができる。また、厚
さ方向への突出部が存在せず薄型化を実現できる。
In addition, since there is no joint compared to the structure in which the support beam and the resonator are joined as in the prior art, there is no loss of force propagation caused by acceleration at the joint, and long-term reliability is achieved. There is an effect that it can be secured.
Furthermore, since the vibrating body 10 is made of quartz and the base 20 and the vibrating arm 21 are integrally formed in the same plane, the frequency temperature characteristic is good, and the through hole 22 and the through hole 22 are integrally formed by photolithography. It is easy and easy to manufacture and can be formed with high accuracy. Further, there is no protrusion in the thickness direction, and a reduction in thickness can be realized.

なお、上述した実施形態1は、擬似両端固定構造を例示したものであるが、片端固定構
造の振動体にも適応可能である。
(変形例1)
In addition, although Embodiment 1 mentioned above illustrates the pseudo | simulation both-ends fixing structure, it is applicable also to the vibrating body of a one-end fixing structure.
(Modification 1)

続いて、実施形態1の変形例1に係る加速度センサついて図面を参照して説明する。変
形例1は、振動体が片端固定構造で一次の屈曲振動をする形態であることを特徴とする。
図2は、変形例1に係る加速度センサの構成を示す斜視図である。図2において、加速
度センサとしての振動体10は、付加質量部25を除いて前述した実施形態1(図1、参
照)と同形状をしている。付加質量部25は、振動腕21の延長上に設けられており、振
動腕21は、貫通孔22によって振動腕部23,24に分割されている。
Next, an acceleration sensor according to Modification 1 of Embodiment 1 will be described with reference to the drawings. Modification 1 is characterized in that the vibrating body has a one-end fixed structure and performs primary bending vibration.
FIG. 2 is a perspective view showing the configuration of the acceleration sensor according to the first modification. In FIG. 2, the vibrating body 10 as an acceleration sensor has the same shape as that of the first embodiment (see FIG. 1) except for the additional mass portion 25. The additional mass portion 25 is provided on an extension of the vibrating arm 21, and the vibrating arm 21 is divided into vibrating arm portions 23 and 24 by through holes 22.

振動腕部23,24の側面には、図1で表される励振電極31〜34が設けられている
。発振回路から励振電極31,32、励振電極33,34それぞれに逆電位の励振信号が
入力されると、振動腕21は、基部20との連結部近傍を振動の節として一次の屈曲振動
をする(矢印Aで図示)。
Excitation electrodes 31 to 34 shown in FIG. 1 are provided on the side surfaces of the vibrating arm portions 23 and 24. When excitation signals having opposite potentials are input from the oscillation circuit to the excitation electrodes 31 and 32 and the excitation electrodes 33 and 34, the resonating arm 21 performs primary bending vibration with the vicinity of the connecting portion with the base 20 as a vibration node. (Indicated by arrow A).

加速度の検出は実施形態1と同様に行う。つまり、振動腕21がX軸方向に所定の共振
周波数で一次の屈曲振動しているときに、+Y軸方向の加速度+Ayが加えられると、振
動腕21の基部20との連結部及び屈曲部には付加質量部25の慣性効果により圧縮応力
が発生する。圧縮応力が発生すると共振周波数は低くなる方向に変化する。また、−Y軸
方向に加速度−Ayが加えられると、振動腕21の基部20との連結部及び屈曲部には引
っ張り応力が発生する。引っ張り応力が発生すると共振周波数は高くなる方向に変化する
。この共振周波数変化を検出回路にて検出し、検出された共振周波数を変換回路(図示せ
ず)で電圧に変換し、加速度として検出することができる。
The acceleration is detected in the same manner as in the first embodiment. In other words, when acceleration + Ay in the + Y-axis direction is applied while the vibrating arm 21 is performing primary bending vibration at a predetermined resonance frequency in the X-axis direction, the connecting portion and the bending portion of the vibrating arm 21 with the base portion 20 are applied. , A compressive stress is generated due to the inertial effect of the additional mass portion 25. When compressive stress is generated, the resonance frequency changes in the direction of lowering. Further, when the acceleration −Ay is applied in the −Y-axis direction, tensile stress is generated in the connecting portion and the bent portion of the vibrating arm 21 with the base portion 20. When a tensile stress is generated, the resonance frequency changes in a higher direction. This change in resonance frequency can be detected by a detection circuit, and the detected resonance frequency can be converted into a voltage by a conversion circuit (not shown) and detected as an acceleration.

なお、振動腕の総長さL1に対する貫通孔22の長さL2の比を変えることで、加速度
による周波数変動量が変動することがシミュレーション及び実験によって確認されている

図3は、振動腕の総長さL1に対する貫通孔の長さL2の比と周波数変動量の関係につ
いて示すグラフである。図3に示すように、加速度(m/s2)に対する周波数変動量(
ppm/(m/s2)は、振動腕の総長さL1に対する貫通孔22の長さL2の比(L2
/L1(%)で表す)に従い変化する。
It has been confirmed by simulation and experiment that the amount of frequency fluctuation due to acceleration varies by changing the ratio of the length L2 of the through hole 22 to the total length L1 of the vibrating arm.
FIG. 3 is a graph showing the relationship between the ratio of the length L2 of the through hole to the total length L1 of the vibrating arm and the amount of frequency fluctuation. As shown in FIG. 3, the amount of frequency fluctuation with respect to acceleration (m / s 2 ) (
ppm / (m / s 2 ) is the ratio of the length L2 of the through hole 22 to the total length L1 of the vibrating arm (L2
/ L1 (expressed in%)).

このグラフから、L2/L1が0のとき(貫通孔22がないとき)、周波数変動量は0
.1ppm/(m/s2)であり、貫通孔22がない場合でも加速度の検出が可能である
ことを示している。しかし、周波数変動量が0.1ppm/(m/s2)では検出感度が
低く、実用上好ましくない。
From this graph, when L2 / L1 is 0 (when there is no through hole 22), the frequency fluctuation amount is 0.
. 1 ppm / (m / s 2 ), indicating that acceleration can be detected even when there is no through hole 22. However, when the frequency fluctuation amount is 0.1 ppm / (m / s 2 ), the detection sensitivity is low, which is not preferable for practical use.

L2/L1が大きくなるに従い周波数変動量が大きくなり、80%近傍で最大値を示す
。そして、L2/L1が80%を中心として±20%の範囲で、周波数変動量が概ね1p
pm/(m/s2)以上の検出感度を示しており、実用上好ましいレベルである。
As L2 / L1 increases, the amount of frequency fluctuation increases and shows a maximum value in the vicinity of 80%. And when L2 / L1 is in the range of ± 20% centering on 80%, the frequency fluctuation amount is about 1p.
The detection sensitivity is pm / (m / s 2 ) or higher, which is a practically preferable level.

このような変形例1によれば、振動体10が片端固定構造で一次の屈曲振動の構造にお
いても、前述した実施形態1と同様な効果が得られる。
(変形例2)
According to the first modification, the same effect as that of the first embodiment described above can be obtained even when the vibrating body 10 has a one-end fixed structure and a primary bending vibration structure.
(Modification 2)

続いて、実施形態1の変形例2に係る加速度センサについて図面を参照して説明する。
変形例2は、振動腕の自由端に一次の屈曲振動をする程度の大きな付加質量部を設けたこ
とに特徴を有している。従って、前述した実施形態1(図1、参照)との相違個所を中心
に説明する。共通部分には実施形態1と同じ符号を附している。
図4は、本変形例に係る振動体を示す正面図である。図4において、振動体10は、基
部20の一辺の中央からY軸方向に梁状の振動腕21が垂直に延出されている。振動腕2
1の幅方向(X軸方向)中央には、厚さ方向(Z軸方向)に貫通し、且つ、長手方向(Y
軸方向)に沿って貫通孔22が開設されている。
Next, an acceleration sensor according to Modification 2 of Embodiment 1 will be described with reference to the drawings.
The modification 2 is characterized in that a large additional mass part that performs primary bending vibration is provided at the free end of the vibrating arm. Therefore, the description will focus on the differences from the first embodiment (see FIG. 1). Common parts are denoted by the same reference numerals as those in the first embodiment.
FIG. 4 is a front view showing a vibrating body according to this modification. In FIG. 4, the vibrating body 10 has a beam-like vibrating arm 21 extending vertically from the center of one side of the base 20 in the Y-axis direction. Vibration arm 2
1 in the center in the width direction (X-axis direction), penetrates in the thickness direction (Z-axis direction), and extends in the longitudinal direction (Y
A through hole 22 is formed along the axial direction.

貫通孔22は実施形態1(図1、参照)と同様な位置、大きさで形成されており、貫通
孔22の長さと付加質量部25を含む振動腕21の総長さとの関係も概ね実施形態1に準
じている。振動腕21の先端部(自由端)には、付加質量部25が形成されている。付加
質量部25は、変形例1(図2、参照)よりも大きく、実施形態1(図1、参照)よりも
小さく設定されている。従って、振動腕21は、基部20との連結部近傍を振動の節とす
る一次の屈曲振動をする。
The through-hole 22 is formed at the same position and size as in the first embodiment (see FIG. 1), and the relationship between the length of the through-hole 22 and the total length of the vibrating arm 21 including the additional mass portion 25 is also generally the embodiment. It is based on 1. An additional mass portion 25 is formed at the tip (free end) of the vibrating arm 21. The additional mass unit 25 is set to be larger than the first modification (see FIG. 2) and smaller than the first embodiment (see FIG. 1). Therefore, the vibrating arm 21 performs primary bending vibration with the vicinity of the connecting portion with the base 20 as a vibration node.

振動腕21に上述したような付加質量部25を設けることにより、振動腕21の質量増
加により、加速度が加えられた際の屈曲部に発生する引っ張り応力または圧縮応力が変形
例1よりも大きくなり、検出感度を高めることができる。
(変形例3)
By providing the additional mass portion 25 as described above to the vibrating arm 21, the tensile stress or the compressive stress generated in the bent portion when acceleration is applied becomes larger than that in the first modification due to the increase in the mass of the vibrating arm 21. , Detection sensitivity can be increased.
(Modification 3)

続いて、実施形態1の変形例3に係る加速度センサについて図面を参照して説明する。
変形例3は、前述した実施形態1では1本の振動腕を備えていることに対し、振動腕を複
数本備えていることに特徴を有している。ここでは、振動腕を2本備える構造を例示して
説明する。
図5は、変形例3に係る振動体を示し、(a)は正面図、(b)は(a)のJ−J切断
面を示す断面図である。図5(a)、(b)において、加速度センサとしての振動体50
は、基部51の一辺から2本の振動腕54,58が垂直に、且つ、平行に延出されている
。つまり、この振動体50は音叉型振動体である。
Next, an acceleration sensor according to Modification 3 of Embodiment 1 will be described with reference to the drawings.
The modified example 3 is characterized in that a plurality of vibrating arms are provided in contrast to the single vibrating arm provided in the first embodiment. Here, a structure including two vibrating arms will be described as an example.
5A and 5B show a vibrating body according to the third modification, in which FIG. 5A is a front view and FIG. 5B is a cross-sectional view showing a JJ section of FIG. 5A and 5B, the vibrating body 50 as an acceleration sensor
The two vibrating arms 54 and 58 are extended from one side of the base 51 vertically and in parallel. That is, the vibrating body 50 is a tuning fork type vibrating body.

振動腕54,58にはそれぞれ、幅方向中央部に貫通孔55,59が開設されている。
これら振動腕54,58と貫通孔55,59それぞれの形状は、前述した実施形態1(図
1、参照)の振動腕21、貫通孔22に相当する。そして、貫通孔55,59を設けるこ
とにより、振動腕54は振動腕部56,57とに分割され、振動腕58は振動腕部60,
61に分割される。振動腕部56,57は先端部を付加質量部54aにて連結され、振動
腕部60,61は先端部を付加質量部58aにて連結されている。
In the vibrating arms 54 and 58, through holes 55 and 59 are formed in the center in the width direction, respectively.
The shapes of the vibrating arms 54 and 58 and the through holes 55 and 59 correspond to the vibrating arm 21 and the through hole 22 of the above-described first embodiment (see FIG. 1). By providing the through holes 55 and 59, the vibrating arm 54 is divided into the vibrating arm portions 56 and 57, and the vibrating arm 58 is divided into the vibrating arm portions 60 and 57.
It is divided into 61. The vibrating arm portions 56 and 57 are connected at their distal ends with an additional mass portion 54a, and the vibrating arm portions 60 and 61 are connected at their distal ends with an additional mass portion 58a.

図5(b)に示すように、振動腕部56,57,60,61それぞれの側面には励振電
極が形成されている。具体的には、振動腕部56の外側面56aには励振電極71、内側
面56bには励振電極72が設けられている。一方、振動腕部57の外側面57aには励
振電極73、内側面57bには励振電極74が形成されている。また、振動腕部60の外
側面60aには励振電極77、内側面60bには励振電極78、振動腕部61の外側面6
1aには励振電極75、内側面61bには励振電極76が形成されている。
As shown in FIG. 5B, excitation electrodes are formed on the side surfaces of the vibrating arm portions 56, 57, 60, and 61, respectively. Specifically, an excitation electrode 71 is provided on the outer side surface 56a of the vibrating arm portion 56, and an excitation electrode 72 is provided on the inner side surface 56b. On the other hand, an excitation electrode 73 is formed on the outer surface 57a of the vibrating arm 57, and an excitation electrode 74 is formed on the inner surface 57b. Further, an excitation electrode 77 is provided on the outer side surface 60 a of the vibrating arm 60, an excitation electrode 78 is provided on the inner side surface 60 b, and the outer side surface 6 of the vibrating arm unit 61.
An excitation electrode 75 is formed on 1a, and an excitation electrode 76 is formed on the inner side surface 61b.

励振電極71,73,76,78は同電位の電極群、励振電極72,74,75,77
は同電位の電極群であり、励振電極71,73,76,78と励振電極72,74,75
,77とに逆電位の励振信号が入力される。このような構成にすることで、振動腕54,
58はそれぞれ矢印B,C方向、つまり、X軸方向にそれぞれが逆相となるように一次の
屈曲振動をする。
The excitation electrodes 71, 73, 76, 78 are an electrode group having the same potential, and the excitation electrodes 72, 74, 75, 77.
Is an electrode group of the same potential, the excitation electrodes 71, 73, 76, 78 and the excitation electrodes 72, 74, 75.
, 77 are inputted with excitation signals having opposite potentials. With this configuration, the vibrating arm 54,
58 performs primary bending vibrations so that the phases are opposite to each other in the directions of arrows B and C, that is, in the X-axis direction.

基部51は、連結部52で振動腕54,58と連結されており、この領域に振動の節が
存在する。連結部52と基部51との間にはくびれ部53が形成されている。くびれ部5
3は、振動腕54,58の振動を固定部に伝達させないために設けられている。
The base 51 is connected to the vibrating arms 54 and 58 by the connecting portion 52, and a vibration node exists in this region. A constricted portion 53 is formed between the connecting portion 52 and the base portion 51. Constriction part 5
3 is provided to prevent the vibrations of the vibrating arms 54 and 58 from being transmitted to the fixed portion.

このような構造は音叉型振動体であり、音叉型振動体は、構造対称性を有し、振動した
ときに振動腕54,58が互いに逆位相で振動することから振動漏れが小さく振動効率が
高いという利点がある。
Such a structure is a tuning fork type vibrating body, and the tuning fork type vibrating body has structural symmetry, and when vibrating, the vibrating arms 54 and 58 vibrate in mutually opposite phases, so that vibration leakage is small and vibration efficiency is low. There is an advantage of high.

また、振動腕54,58のそれぞれに貫通孔55,59が設けられているために、振動
腕54,58の断面積が小さくなるので、発生する伸縮応力が大きくなる。従って、振動
腕を複数有する形状であっても加速度による収縮応力や引っ張り応力が高くなり共振周波
数変化量が大きく、高い検出感度が得られる。
なお、本実施形態では、振動腕を2本備える構造を例示しているが、3本でもそれ以上
としてもよい。3本の場合には、中央の振動腕を検出用とすることができる。
(実施形態2)
Further, since the through-holes 55 and 59 are provided in the vibrating arms 54 and 58, respectively, the cross-sectional area of the vibrating arms 54 and 58 is reduced, so that the generated expansion / contraction stress is increased. Therefore, even in the shape having a plurality of vibrating arms, the contraction stress and the tensile stress due to acceleration are increased, and the amount of change in resonance frequency is large, so that high detection sensitivity can be obtained.
In the present embodiment, a structure including two vibrating arms is illustrated, but three or more may be used. In the case of three, the center vibrating arm can be used for detection.
(Embodiment 2)

続いて、実施形態2に係る加速度センサについて図面を参照して説明する。実施形態2
は、前述した実施形態1及び変形例が擬似両端固定構造または片端固定構造であることに
対して、両端固定構造としたところに特徴を有している。
図6は、実施形態2に係る加速度センサを示す正面図である。図6において、加速度セ
ンサ40は、振動体10,11の2組の振動体が共通の付加質量部25において直線状に
連結されて構成されている。
Next, the acceleration sensor according to the second embodiment will be described with reference to the drawings. Embodiment 2
Is characterized in that it has a double-end fixing structure, whereas the first embodiment and the modification described above have a pseudo double-end fixing structure or a single-end fixing structure.
FIG. 6 is a front view showing the acceleration sensor according to the second embodiment. In FIG. 6, the acceleration sensor 40 is configured by connecting two sets of vibrating bodies 10 and 11 in a straight line at a common additional mass portion 25.

図6に示すように、加速度センサ40の重心位置Gの右側は、基部20と振動腕21と
付加質量部25とから構成される振動体10、左側は基部45と振動腕41と付加質量部
25とから構成される振動体11である。振動腕21は貫通孔22によって分割された振
動腕部23,24を有し、それぞれに図1(b)に示すような励振電極が設けられている
As shown in FIG. 6, the right side of the gravity center G of the acceleration sensor 40 is the vibrating body 10 including the base 20, the vibrating arm 21, and the additional mass unit 25, and the left side is the base 45, the vibrating arm 41, and the additional mass unit. The vibrating body 11 is composed of 25. The resonating arm 21 has resonating arm portions 23 and 24 divided by a through-hole 22, and excitation electrodes as shown in FIG.

一方、振動腕41は貫通孔42によって分割された振動腕部43,44を有し、それぞ
れに図1(b)に示すような励振電極が設けられている。従って、付加質量部25は、振
動体10及び振動体11の共通付加質量部である。加速度センサ40は、重心位置Gに対
して点対称形状であって、共通の付加質量部25において振動体10と振動体11の2組
の振動体が直線状に連結された、基部20及び基部45を固定部とする両端固定構造であ
る。また、付加質量部25は、基部20,45と同等または、それらよりも大きな質量と
なる平面サイズを有している。
On the other hand, the resonating arm 41 has resonating arm portions 43 and 44 divided by a through hole 42, and each is provided with an excitation electrode as shown in FIG. Therefore, the additional mass unit 25 is a common additional mass unit for the vibrating body 10 and the vibrating body 11. The acceleration sensor 40 has a point-symmetric shape with respect to the center of gravity position G, and two bases of the vibrator 10 and the vibrator 11 are linearly connected at the common additional mass part 25, and the base 20 and the base It is a both-ends fixing structure having 45 as a fixing part. Further, the additional mass portion 25 has a planar size that is equal to or larger than the base portions 20 and 45.

ここで、振動腕21,41それぞれに逆電位、逆位相、同じ周波数の励振信号を入力す
ると、付加質量部25は充分大きな質量を有しているため、矢印D、矢印E方向の変位は
極わずかである。従って、振動腕21は、振動腕21と基部20との連結部、及び振動腕
21と付加質量部25との連結部近傍にある振動の節を有し、矢印D’方向または矢印E
’方向に二次の屈曲振動となる。また、振動腕41は、振動腕41と基部45との連結部
、及び振動腕41と付加質量部25との連結部近傍の振動の節を有し、振動腕21とは逆
位相の二次の屈曲振動をする。
Here, when an excitation signal having a reverse potential, a reverse phase, and the same frequency is input to each of the vibrating arms 21 and 41, the additional mass portion 25 has a sufficiently large mass. It is slight. Accordingly, the resonating arm 21 has a connecting portion between the resonating arm 21 and the base portion 20 and a vibration node in the vicinity of the connecting portion between the resonating arm 21 and the additional mass portion 25, and the direction of the arrow D ′ or the arrow E
'Secondary bending vibration in the direction. The resonating arm 41 has a connecting portion between the resonating arm 41 and the base portion 45 and a vibration node in the vicinity of the connecting portion between the resonating arm 41 and the additional mass portion 25. Of bending vibration.

上述した実施形態2の構造によれば、加速度センサ40は付加質量部25を挟んで対向
する振動体10,11を有する両端固定構造となる。この際、それぞれの振動腕21,4
1は、逆位相の高次の屈曲振動モードを有し、振動バランスがよい振動体を構成する。つ
まり高いQ値が得られる。
According to the structure of the second embodiment described above, the acceleration sensor 40 has a both-ends fixed structure having the vibrating bodies 10 and 11 that are opposed to each other with the additional mass portion 25 interposed therebetween. At this time, the respective vibrating arms 21 and 4
1 has an antiphase high-order bending vibration mode and constitutes a vibrating body having a good vibration balance. That is, a high Q value is obtained.

また、対向する振動腕21,41は、Y軸方向の加速度が加えられたとき、一方に収縮
応力が発生し、他方の振動腕には引っ張り応力が発生する。このような構造の場合、両振
動体の共振周波数の差動をとることで周波数温度特性の影響を打ち消すことができるとい
う効果がある。
(実施形態3)
Further, when acceleration in the Y-axis direction is applied to the opposing vibrating arms 21 and 41, contraction stress is generated on one side, and tensile stress is generated on the other vibrating arm. In the case of such a structure, there is an effect that the influence of the frequency temperature characteristic can be canceled by taking the difference between the resonance frequencies of both vibrators.
(Embodiment 3)

続いて、実施形態3に係る加速度センサについて図面を参照して説明する。実施形態3
は、前述した実施形態1,2では振動体として水晶を用いていることに対して恒弾性材料
を用いることを特徴とする。本実施形態の振動体の形状は、前述した実施形態1,2形状
と同じ考え方が応用できるが、ここでは、実施形態1(図1、参照)と同じ形状のものを
例示して説明する。
図7は、実施形態3に係る振動体を示し、(a)は正面図、(b)は(a)のK−K切
断面を示す断面図である。図7(a)、(b)において、振動体80は、基部81の一辺
から垂直方向に振動腕82が延出されて構成されている。基部81は、振動体80を図示
しないパッケージの基台に固定するための固定部である。振動腕82の幅方向中央には、
厚さ方向に貫通し、且つ、長手方向に長い貫通孔83が開設されている。
Next, an acceleration sensor according to Embodiment 3 will be described with reference to the drawings. Embodiment 3
Is characterized in that a constant elastic material is used in contrast to the use of quartz as the vibrator in the first and second embodiments. Although the same concept as the shapes of the first and second embodiments can be applied to the shape of the vibrating body of the present embodiment, here, the same shape as that of the first embodiment (see FIG. 1) will be described as an example.
FIG. 7: shows the vibrating body which concerns on Embodiment 3, (a) is a front view, (b) is sectional drawing which shows the KK cut surface of (a). 7A and 7B, the vibrating body 80 is configured by extending a vibrating arm 82 from one side of a base 81 in the vertical direction. The base part 81 is a fixing part for fixing the vibrating body 80 to a base of a package (not shown). In the center of the vibrating arm 82 in the width direction,
A through hole 83 penetrating in the thickness direction and long in the longitudinal direction is formed.

なお、振動体80は、ニッケル、鉄、クロム、チタン、あるいはそれらの合金であるエ
リンバ、鉄−ニッケル合金などの恒弾性材料からなり、所望の共振周波数、サイズに対応
して選択する。
The vibrating body 80 is made of a constant elastic material such as nickel, iron, chromium, titanium, or an alloy thereof such as Elinba or an iron-nickel alloy, and is selected according to a desired resonance frequency and size.

振動腕82は、貫通孔83を設けることにより振動腕部84,85に分割されている。
振動腕部84,85の先端部は付加質量部82aで連結されている。そして、振動腕部8
4,85それぞれの外側側面には、圧電素子膜86,87が形成されている。図7(b)
に示すように、圧電素子膜86には表裏両面のそれぞれに上部電極88a、下部電極88
bが形成されている。また、下部電極88bと振動腕部84の外側側面との間には絶縁性
膜(図示せず)が形成されている。
The vibrating arm 82 is divided into vibrating arm portions 84 and 85 by providing a through hole 83.
The tip ends of the vibrating arm portions 84 and 85 are connected by an additional mass portion 82a. And the vibrating arm 8
Piezoelectric element films 86 and 87 are formed on the outer side surfaces of the four and 85, respectively. FIG. 7 (b)
As shown in FIG. 4, the piezoelectric element film 86 has an upper electrode 88a and a lower electrode 88 on both the front and back surfaces.
b is formed. An insulating film (not shown) is formed between the lower electrode 88 b and the outer side surface of the vibrating arm portion 84.

一方、圧電素子膜87には表裏両面のそれぞれに上部電極89a,下部電極89bが形
成されている。また、下部電極89bと振動腕部85の外側側面との間には絶縁性膜(図
示せず)が形成されている。
On the other hand, an upper electrode 89a and a lower electrode 89b are formed on the front and back surfaces of the piezoelectric element film 87, respectively. In addition, an insulating film (not shown) is formed between the lower electrode 89 b and the outer side surface of the vibrating arm portion 85.

圧電素子膜86,87にはそれぞれ逆電位の励振信号が入力されることにより、振動腕
82は、実施形態1と同様な二次の屈曲振動をし、所定の共振周波数で安定した振動を継
続する。
なお、圧電素子膜86,87の材料としては、チタン酸鉛(PbTiO3)、チタン酸
ジルコン酸鉛(PZT(登録商標))、酸化亜鉛(ZnO)等を採用することができる。
When an excitation signal having a reverse potential is input to each of the piezoelectric element films 86 and 87, the vibrating arm 82 performs a secondary bending vibration similar to that in the first embodiment, and continues a stable vibration at a predetermined resonance frequency. To do.
As materials for the piezoelectric element films 86 and 87, lead titanate (PbTiO 3 ), lead zirconate titanate (PZT (registered trademark)), zinc oxide (ZnO), or the like can be used.

従って、上述した実施形態3によれば、前述した実施形態1の効果と、振動体80に恒
弾性材料を用いることにより構造的強度が高まり、振動腕部84,85の断面積を小さく
しても、強い加速度領域の検出にも対応できるという効果がある。
(実施形態4)
Therefore, according to the above-described third embodiment, the structural strength is increased by using the constant elastic material for the vibrating body 80 and the cross-sectional area of the vibrating arm portions 84 and 85 is reduced. However, there is an effect that it can cope with detection of a strong acceleration region.
(Embodiment 4)

続いて、実施形態4に係る加速度センサについて図面を参照して説明する。実施形態4
は、複数の振動腕それぞれに貫通孔が設けられていることに特徴を有している。なお、本
実施形態では、振動腕が2本の場合を例示して説明する。
図8は、本実施形態に係る加速度センサを示し、(a)は正面図、(b)は励振電極の
構成を拡大して示す部分正面図である。図8(a)において、加速度センサとしての振動
体100は、基部102の1辺から貫通孔101によって分割された振動腕105,11
2が、互いに平行に延出され、それらの先端部は付加質量部113によって連結された片
端固定構造である。
Next, an acceleration sensor according to Embodiment 4 will be described with reference to the drawings. Embodiment 4
Is characterized in that a through hole is provided in each of the plurality of vibrating arms. In the present embodiment, a case where there are two vibrating arms will be described as an example.
8A and 8B show the acceleration sensor according to the present embodiment, where FIG. 8A is a front view and FIG. 8B is a partial front view showing an enlarged configuration of the excitation electrode. In FIG. 8A, a vibrating body 100 as an acceleration sensor includes vibrating arms 105 and 11 divided by a through hole 101 from one side of a base portion 102.
2 are extended in parallel to each other, and the tip portions thereof are one-end fixing structures connected by an additional mass portion 113.

また、振動腕105は、貫通孔106を開設することによって振動腕部107,108
が形成され、振動腕112は、貫通孔109を開設することによって振動腕部110,1
11が形成されている。なお、貫通孔106,109の長さは振動腕105,112の長
さに略等しい。また、振動腕105と振動腕112とは、中心軸Pに対して対称形である
In addition, the vibrating arm 105 is provided with the through-hole 106 so that the vibrating arm portions 107 and 108 are opened.
And the vibrating arm 112 is formed by opening the through-hole 109 so that the vibrating arm portions 110 and 1
11 is formed. Note that the lengths of the through holes 106 and 109 are substantially equal to the lengths of the vibrating arms 105 and 112. The vibrating arm 105 and the vibrating arm 112 are symmetrical with respect to the central axis P.

基部102は、振動腕105,112との連結部104と、くびれ部103とを有し、
付加質量部113においても振動腕105,112との連結部115と、くびれ部114
とを有して構成されている。そして、図8(b)に示すように、振動腕105,112そ
れぞれの両側側面と、貫通孔106,109内部側面には励振電極が形成されている。
The base portion 102 includes a connecting portion 104 with the vibrating arms 105 and 112 and a constricted portion 103.
Also in the additional mass portion 113, the connecting portion 115 with the vibrating arms 105 and 112 and the constricted portion 114.
And is configured. As shown in FIG. 8B, excitation electrodes are formed on both side surfaces of the vibrating arms 105 and 112 and inner side surfaces of the through holes 106 and 109, respectively.

各励振電極は図8(b)に示すように、振動腕部110の外側側面に励振電極120、
貫通孔109の内側側面に励振電極121,122が設けられ、貫通孔101の内側側面
には励振電極123,124、貫通孔106の内側側面には励振電極125,126が設
けられ、さらに、振動腕部107の外側側面には励振電極127が設けられている。
As shown in FIG. 8B, each excitation electrode has an excitation electrode 120 on the outer side surface of the vibrating arm 110.
Excitation electrodes 121 and 122 are provided on the inner side surface of the through hole 109, excitation electrodes 123 and 124 are provided on the inner side surface of the through hole 101, excitation electrodes 125 and 126 are provided on the inner side surface of the through hole 106, and vibration An excitation electrode 127 is provided on the outer side surface of the arm portion 107.

これらの励振電極120〜123と、励振電極124〜127とは、中心軸Pに対して
対称形となるように構成されている。そして、励振電極120,122,125,127
は同電位の第1電極群であって、励振電極121,123,124,126は同電位の第
2電極群である。
The excitation electrodes 120 to 123 and the excitation electrodes 124 to 127 are configured to be symmetrical with respect to the central axis P. And excitation electrode 120,122,125,127.
Is a first electrode group having the same potential, and the excitation electrodes 121, 123, 124, and 126 are second electrode groups having the same potential.

ここで、第1電極群と第2電極群とに逆相の電位を印加することにより、振動腕105
及び振動腕112は、基部102の連結部に振動の節を有する一次の屈曲振動をする。
Here, by applying a reverse-phase potential to the first electrode group and the second electrode group, the vibrating arm 105
The vibrating arm 112 performs primary bending vibration having a vibration node at the connecting portion of the base portion 102.

この加速度センサに軸方向の加速度が加えられると、振動腕105,112に伸縮応力
が発生することによる共振周波数の変化を生じ、この共振周波数の変化を加速度として検
出する。
なお、本実施形態における貫通孔106,109に対して励振電極の配置は、振動腕1
05,112が一次の屈曲振動をするために様々に設定することが可能である。
When an acceleration in the axial direction is applied to the acceleration sensor, a change in the resonance frequency is caused by the expansion and contraction stress generated in the vibrating arms 105 and 112, and the change in the resonance frequency is detected as an acceleration.
In addition, the arrangement of the excitation electrode with respect to the through holes 106 and 109 in the present embodiment is such that the vibrating arm 1
It is possible to set various values for 05 and 112 to perform primary bending vibration.

例えば、励振電極120〜127の全部または一部を、振動腕105,112の基部1
02の方向に偏らせて配置させることができる。一次の屈曲振動において、振動による歪
みが大きく発生する部分は、振動腕105、112と基部102(連結部104)との連
結部付近となるので、この歪みが大きい部分に励振電極を設けてもよい。
For example, all or part of the excitation electrodes 120 to 127 may be connected to the base 1 of the vibrating arms 105 and 112.
It can be biased in the direction of 02. In the primary bending vibration, the portion where the distortion caused by the vibration is large is in the vicinity of the connecting portion between the vibrating arms 105 and 112 and the base portion 102 (the connecting portion 104). Good.

同様に、本実施形態における貫通孔106,109の形状、開設位置、それに伴う励振
電極の配置は様々に設定することが可能である。
(実施形態5)
Similarly, the shape of the through holes 106 and 109 in this embodiment, the opening position, and the arrangement of the excitation electrodes associated therewith can be set in various ways.
(Embodiment 5)

次に、実施形態5に係る加速度センサについて図面を参照して説明する。本実施形態は
、貫通孔が基部方向に偏らせて配置されていることを特徴とする。従って、実施形態4(
図8、参照)と異なる部分を中心に説明する。
図9は、実施形態5に係る振動体を示し、(a)は正面図、(b)は励振電極の構成を
拡大して示す部分正面図である。図9(a)において、振動腕105,112にはそれぞ
れ貫通孔151,153が開設されている。貫通孔151,153は、基部102側に偏
って開設され、連結部104から振動腕105,112の長さの略中央部までの範囲に設
けられる。
Next, an acceleration sensor according to Embodiment 5 will be described with reference to the drawings. The present embodiment is characterized in that the through holes are arranged so as to be biased toward the base portion. Therefore, the fourth embodiment (
The description will focus on the parts different from FIG.
9A and 9B show a vibrating body according to the fifth embodiment, where FIG. 9A is a front view and FIG. 9B is a partial front view showing an enlarged configuration of an excitation electrode. In FIG. 9A, through-holes 151 and 153 are formed in the vibrating arms 105 and 112, respectively. The through holes 151 and 153 are opened to be biased toward the base portion 102 and are provided in a range from the connecting portion 104 to the substantially central portion of the length of the vibrating arms 105 and 112.

なお、貫通孔151,153は、振動腕105,112が一次の屈曲振動の際に発生す
る歪みが大きい範囲に設けられている。
Note that the through holes 151 and 153 are provided in a range where the distortion generated when the vibrating arms 105 and 112 undergo primary bending vibration is large.

励振電極は、図9(b)に示すように、振動腕105と振動腕112の外側側面と、貫
通孔101,151,153の内側側面に設けられる。貫通孔101の内側側面には励振
電極123,124、貫通孔153の内側側面には励振電極137,138、貫通孔15
1の内側側面には励振電極141,142が設けられている。また、振動腕105の両側
側面の励振電極124,127は、概ね振動腕105の長さ範囲とし、振動腕112の両
側側面の励振電極120,123は、概ね振動腕112の長さ範囲とする。
As shown in FIG. 9B, the excitation electrodes are provided on the outer side surfaces of the vibrating arms 105 and 112 and the inner side surfaces of the through holes 101, 151, and 153. Excitation electrodes 123 and 124 are provided on the inner side surface of the through hole 101, and excitation electrodes 137 and 138 are provided on the inner side surface of the through hole 153.
Excitation electrodes 141 and 142 are provided on the inner side surface of 1. Further, the excitation electrodes 124 and 127 on both side surfaces of the vibrating arm 105 are generally in the length range of the vibrating arm 105, and the excitation electrodes 120 and 123 on both side surfaces of the vibrating arm 112 are generally in the length range of the vibrating arm 112. .

これらの励振電極120,123,137,138と、励振電極124,127,14
1,142とは、中心軸Pに対して対称形となるように構成されている。そして、励振電
極120,138,141,127は同電位の第1電極群であって、励振電極137,1
23,124,142は同電位の第2電極群である。
These excitation electrodes 120, 123, 137, 138 and excitation electrodes 124, 127, 14
1 and 142 are configured to be symmetrical with respect to the central axis P. The excitation electrodes 120, 138, 141, 127 are a first electrode group having the same potential, and the excitation electrodes 137, 1
Reference numerals 23, 124 and 142 denote a second electrode group having the same potential.

ここで、第1電極群と第2電極群とに逆相の電位を印加することにより、振動腕105
及び振動腕112は、基部102の連結部に振動の節を有する一次の屈曲振動をする。
Here, by applying a reverse-phase potential to the first electrode group and the second electrode group, the vibrating arm 105
The vibrating arm 112 performs primary bending vibration having a vibration node at the connecting portion of the base portion 102.

この加速度センサに軸方向の加速度が加えられると、振動腕105,112に伸縮応力
が発生することによる共振周波数の変化を生じ、この共振周波数の変化を加速度として検
出する。
When an acceleration in the axial direction is applied to the acceleration sensor, a change in the resonance frequency is caused by the expansion and contraction stress generated in the vibrating arms 105 and 112, and the change in the resonance frequency is detected as an acceleration.

なお、上述した励振電極の配置は1例であって、励振電極120,123,124,1
27を励振電極137,138,141,142と同じ長さとなるように設けてもよい。
(実施形態6)
The arrangement of the excitation electrodes described above is an example, and the excitation electrodes 120, 123, 124, 1
27 may be provided to have the same length as the excitation electrodes 137, 138, 141, 142.
(Embodiment 6)

続いて、実施形態6に係る加速度センサについて図面を参照して説明する。実施形態6
は、各振動腕それぞれに複数の貫通孔が開設されていることを特徴とする。従って、実施
形態4(図8、参照)と異なる部分を中心に説明する。また、共通部分には同じ符号を附
している。
図10は、実施形態6に係る加速度センサを示し、(a)は正面図、(b)は励振電極
の構成を拡大して示す部分正面図である。図10(a)において、振動腕105には貫通
孔150,155,151が、振動腕112には貫通孔152,156,153が開設さ
れている。
Next, an acceleration sensor according to Embodiment 6 will be described with reference to the drawings. Embodiment 6
Is characterized in that a plurality of through holes are formed in each vibrating arm. Therefore, it demonstrates centering on a different part from Embodiment 4 (refer FIG. 8). In addition, common parts are denoted by the same reference numerals.
10A and 10B show an acceleration sensor according to the sixth embodiment, where FIG. 10A is a front view and FIG. 10B is a partial front view showing an enlarged configuration of excitation electrodes. In FIG. 10A, the vibrating arm 105 has through holes 150, 155 and 151, and the vibrating arm 112 has through holes 152, 156 and 153.

貫通孔150,152は、振動腕105,112それぞれの付加質量部113の近傍に
設けられている。具体的には、貫通孔150,152は付加質量部113から振動腕10
5,112の長手方向全長の概ね30%の範囲に設けられる。また、貫通孔151,15
3は、基部102の近傍に設けられている。なお、貫通孔151,153は基部102か
ら振動腕105,112の長手方向全長の概ね30%の範囲に設けられる。さらに、振動
腕105,112の長手方向中央部には、貫通孔155,156が設けられ、貫通孔15
5,156は、振動腕105,112の長手方向中央を中心として振動腕105,112
の長手方向全長の60%以内の範囲に設けられる。
The through holes 150 and 152 are provided in the vicinity of the additional mass portions 113 of the vibrating arms 105 and 112, respectively. Specifically, the through holes 150 and 152 extend from the additional mass portion 113 to the vibrating arm 10.
5,112 in the range of approximately 30% of the entire length in the longitudinal direction. Also, the through holes 151 and 15
3 is provided in the vicinity of the base 102. The through holes 151 and 153 are provided in a range of approximately 30% of the entire length in the longitudinal direction of the vibrating arms 105 and 112 from the base 102. Furthermore, through holes 155 and 156 are provided in the longitudinal center of the vibrating arms 105 and 112, and the through holes 15
Reference numerals 5 and 156 denote the vibrating arms 105 and 112 with the center in the longitudinal direction of the vibrating arms 105 and 112 as the center.
In the range within 60% of the total length in the longitudinal direction.

貫通孔151,153は振動腕105,112が一次の屈曲振動をする際に発生する歪
みが最も大きい位置に設けられ、貫通孔155,156、貫通孔150,152は歪みは
徐々に小さくなる位置である。そして、振動腕105,112の外側側面と貫通孔150
〜153,155,156の内側側面には、それぞれ励振電極が設けられている。
The through holes 151 and 153 are provided at positions where the distortion generated when the vibrating arms 105 and 112 undergo primary bending vibration is the largest, and the through holes 155 and 156 and the through holes 150 and 152 are positions where the distortion gradually decreases. It is. The outer side surfaces of the vibrating arms 105 and 112 and the through hole 150
Excitation electrodes are provided on the inner side surfaces of ˜153, 155, and 156, respectively.

図10(b)に示すように、振動腕105の外側側面には励振電極127が設けられて
いる。また、貫通孔150の内側側面には励振電極125,126、貫通孔151の内側
側面には励振電極141,142、貫通孔155の内側側面には励振電極133,134
が設けられている。また、貫通孔101の内側側面には励振電極123,124、貫通孔
152には励振電極121,122、貫通孔156の内側側面には励振電極129,13
0、貫通孔153の内側側面には励振電極137,138が設けられている。また、振動
腕112の外側側面には励振電極120が設けられている。これら励振電極は、中心軸P
に対して対称である。
As shown in FIG. 10B, the excitation electrode 127 is provided on the outer side surface of the vibrating arm 105. Further, excitation electrodes 125 and 126 are provided on the inner side surface of the through hole 150, excitation electrodes 141 and 142 are provided on the inner side surface of the through hole 151, and excitation electrodes 133 and 134 are provided on the inner side surface of the through hole 155.
Is provided. Excitation electrodes 123 and 124 are provided on the inner side surface of the through hole 101, excitation electrodes 121 and 122 are provided on the through hole 152, and excitation electrodes 129 and 13 are provided on the inner side surface of the through hole 156.
0, excitation electrodes 137 and 138 are provided on the inner side surface of the through hole 153. An excitation electrode 120 is provided on the outer side surface of the vibrating arm 112. These excitation electrodes have a central axis P
Is symmetric.

なお、励振電極120,123,124,127は同電位の第1電極群であって、励振
電極121,122,129,130,137,138,125,126,133,13
4,141,142は同電位の第2電極群である。
The excitation electrodes 120, 123, 124, 127 are a first electrode group having the same potential, and the excitation electrodes 121, 122, 129, 130, 137, 138, 125, 126, 133, 13
Reference numerals 4, 141, 142 denote second electrode groups having the same potential.

ここで、第1電極群と第2電極群とに逆相の電位を印加することにより、振動腕105
及び振動腕112は、基部102の連結部104に振動の節を有する一次の屈曲振動をす
る。
Here, by applying a reverse-phase potential to the first electrode group and the second electrode group, the vibrating arm 105
The vibrating arm 112 performs primary bending vibration having a vibration node at the connecting portion 104 of the base portion 102.

この加速度センサに軸方向の加速度が加えられると、振動腕105,112に伸縮応力
が発生することによる共振周波数の変化を生じ、この共振周波数の変化を加速度として検
出する。
When an acceleration in the axial direction is applied to the acceleration sensor, a change in the resonance frequency is caused by the expansion and contraction stress generated in the vibrating arms 105 and 112, and the change in the resonance frequency is detected as an acceleration.

なお、上述した実施形態6における励振電極の構成は1例であって、例えば、励振電極
120,123,124,127は、貫通孔150,151,152,153,155,
156それぞれに対向するように分割した構成としてもよい。
In addition, the structure of the excitation electrode in Embodiment 6 mentioned above is an example, For example, excitation electrode 120,123,124,127 is the through-hole 150,151,152,153,155,155.
It is good also as a structure divided | segmented so that each of 156 might be opposed.

以上説明したように、実施形態4では、振動腕105,112それぞれの長手方向全体
にわたって貫通孔151,153が設けられ、また、実施形態5では基部102の近傍に
貫通孔106,109が設けられ、実施形態6では、さらに振動腕105,112の長手
方向中央部に貫通孔155,156が設けられている。従って、基部102(連結部10
4)近傍に振動の節を有する一次の屈曲振動において発生する歪みの大きい位置と、それ
よりは小さいが歪みが発生する位置に貫通孔を設けていることから、振動腕105,11
2の変形する位置の断面積が小さくなり発生する応力が大きくなる。また、加速度を加え
たときの振動腕105,112の変位量が大きくとれることから共振周波数変化量が大き
くなり検出感度を高めることができる。
As described above, in the fourth embodiment, the through holes 151 and 153 are provided over the entire longitudinal direction of the vibrating arms 105 and 112, and in the fifth embodiment, the through holes 106 and 109 are provided in the vicinity of the base portion 102. In the sixth embodiment, through-holes 155 and 156 are further provided in the longitudinal center portions of the vibrating arms 105 and 112. Accordingly, the base 102 (the connecting portion 10
4) Since the through-holes are provided at the position where the distortion generated in the primary bending vibration having the vibration node in the vicinity is large and the position where the distortion occurs although it is smaller than that, the vibrating arms 105 and 11 are provided.
The cross-sectional area of the deforming position 2 becomes smaller and the generated stress becomes larger. Further, since the displacement amount of the vibrating arms 105 and 112 when acceleration is applied can be increased, the amount of change in the resonance frequency is increased, and the detection sensitivity can be increased.

また、前述した実施形態1〜実施形態3よりもさらに励振電極間の距離が短くなり電界
効率が高まる。このことから低消費電力化が可能となるという効果がある。
(実施形態7)
In addition, the distance between the excitation electrodes is further reduced as compared with the first to third embodiments, and the electric field efficiency is increased. This has the effect of reducing power consumption.
(Embodiment 7)

続いて、実施形態7に係る加速度センサについて図面を参照して説明する。実施形態7
は、前述した実施形態4〜実施形態6による加速度センサ(振動体)が片端固定構造であ
ることに対して、両端固定構造としたところに特徴を有している。
図11は、実施形態7に係る加速度センサを示す正面図である。図11において、加速
度センサ200は、振動体100,180が共通の付加質量部113において2組が直線
状に連結されて構成されている。
Next, an acceleration sensor according to Embodiment 7 will be described with reference to the drawings. Embodiment 7
Is characterized in that the acceleration sensor (vibrating body) according to Embodiments 4 to 6 described above has a one-end fixing structure, but has a two-end fixing structure.
FIG. 11 is a front view showing an acceleration sensor according to the seventh embodiment. In FIG. 11, the acceleration sensor 200 is configured such that two sets are connected in a straight line at an additional mass portion 113 where the vibrating bodies 100 and 180 are common.

図11に示すように、加速度センサ200の重心位置Gの右側は、基部102と貫通孔
101によって分割された振動腕105,112と付加質量部113とから構成される振
動体100である。また、左側は基部160と貫通孔163によって分割された振動腕1
64,165と付加質量部113とから構成される振動体180である。振動腕105,
112は貫通孔101によって分割されて形成されている。また、振動腕105は貫通孔
106を有し、振動腕112は貫通孔109を有している。
一方、振動腕164には貫通孔166、振動腕165には貫通孔168が開設されてい
る。
As shown in FIG. 11, the right side of the center of gravity position G of the acceleration sensor 200 is a vibrating body 100 composed of vibrating arms 105 and 112 and an additional mass portion 113 divided by a base portion 102 and a through hole 101. The left side is the vibrating arm 1 divided by the base 160 and the through-hole 163.
The vibrating body 180 includes 64 and 165 and the additional mass portion 113. Vibrating arm 105,
Reference numeral 112 is formed by being divided by the through hole 101. The vibrating arm 105 has a through hole 106, and the vibrating arm 112 has a through hole 109.
On the other hand, a through hole 166 is formed in the vibrating arm 164, and a through hole 168 is formed in the vibrating arm 165.

また、基部102には、振動腕105,112が連結される連結部104と、くびれ部
103とが設けられている。振動腕105,112が連結される付加質量部113には、
連結部115と、くびれ部114とが設けられている。
The base portion 102 is provided with a connecting portion 104 to which the vibrating arms 105 and 112 are connected and a constricted portion 103. In the additional mass part 113 to which the vibrating arms 105 and 112 are connected,
A connecting portion 115 and a constricted portion 114 are provided.

一方、振動体180においては、基部160には、振動腕164,165が連結される
連結部162と、くびれ部161とが設けられている。振動腕164,165が連結され
る付加質量部113には、連結部118と、くびれ部119とが設けられている。
On the other hand, in the vibrating body 180, the base portion 160 is provided with a connecting portion 162 to which the vibrating arms 164 and 165 are connected, and a constricted portion 161. The additional mass portion 113 to which the vibrating arms 164 and 165 are connected is provided with a connecting portion 118 and a constricted portion 119.

付加質量部113は、振動体100と振動体180との共通付加質量部であって、基部
102,160と同等か大きい質量を有して平面形状が設定されている。そして、加速度
センサ200は、重心位置Gに対して点対称形状である。従って、加速度センサ200は
、共通の付加質量部113において振動体100と、振動体100と同形状の振動体18
0とが直線状に連結され、基部102及び基部160を基台への固定部とする両端固定構
造である。なお、振動体100,180それぞれは、前述した実施形態4(図8、参照)
と励振電極を含め同じ構成である。
The additional mass portion 113 is a common additional mass portion for the vibrating body 100 and the vibrating body 180 and has a mass that is equal to or larger than that of the base portions 102 and 160 and has a planar shape. The acceleration sensor 200 is point-symmetric with respect to the gravity center position G. Therefore, the acceleration sensor 200 includes the vibrating body 100 and the vibrating body 18 having the same shape as the vibrating body 100 in the common additional mass unit 113.
This is a double-end fixing structure in which 0 is linearly connected and the base 102 and the base 160 are fixed to the base. Each of the vibrating bodies 100 and 180 is the same as that in the fourth embodiment described above (see FIG. 8).
And the excitation electrode.

ここで、振動腕105,112及び振動腕164,165それぞれに前述した実施形態
4と同様に逆電位、逆位相、同じ周波数の励振信号を入力すると、付加質量部113が十
分大きな質量を有しているためほとんど変位せず、振動腕105,112と振動腕164
,165は互いに基部102(連結部104),160(連結部162)、付加質量部1
13との連結部近傍を振動の節とする二次の屈曲振動となる。
Here, if the excitation signals having the reverse potential, the reverse phase, and the same frequency are input to the vibrating arms 105 and 112 and the vibrating arms 164 and 165, respectively, as in the fourth embodiment, the additional mass unit 113 has a sufficiently large mass. Therefore, the vibrating arms 105 and 112 and the vibrating arms 164 are hardly displaced.
, 165 are the base part 102 (connecting part 104), 160 (connecting part 162) and the additional mass part 1
This is a secondary bending vibration in which the vicinity of the connecting portion to the vibration 13 is a vibration node.

従って、上述した実施形態7によれば、付加質量部113を挟んで対向する振動体10
0,180を有する両端固定構造となる。この際、振動腕105,112と振動腕164
,165とは、逆位相の二次の屈曲振動モードを有し、振動バランスがよい振動体を構成
する。つまり高いQ値が得られる。
Therefore, according to the seventh embodiment described above, the vibrating bodies 10 that face each other with the additional mass portion 113 interposed therebetween.
Both ends are fixed structure having 0,180. At this time, the vibrating arms 105 and 112 and the vibrating arm 164
, 165 constitutes a vibrating body having an antiphase secondary bending vibration mode and a good vibration balance. That is, a high Q value is obtained.

また、対向する振動腕105,112と振動腕164,165は、Y軸方向の加速度が
加えられたとき、一方に収縮応力が発生し、他方の振動腕には引っ張り応力が発生する。
このような構造の場合、両振動体の共振周波数の差動をとることで周波数温度特性の影響
を打ち消すことができるという効果がある。
In addition, when the acceleration in the Y-axis direction is applied to the opposing vibrating arms 105 and 112 and the vibrating arms 164 and 165, contraction stress is generated on one side, and tensile stress is generated on the other vibrating arm.
In the case of such a structure, there is an effect that the influence of the frequency temperature characteristic can be canceled by taking the difference between the resonance frequencies of both vibrators.

なお、本実施形態の構成における貫通孔は、前述した実施形態5(図9、参照)のよう
に基部102側に偏らせる構成してもよく、実施形態6の(図10、参照)のように、振
動腕105,112のそれぞれに複数設ける構造としてもよい。
In addition, the through hole in the configuration of the present embodiment may be configured to be biased toward the base 102 as in the above-described fifth embodiment (see FIG. 9), or as in the sixth embodiment (see FIG. 10). In addition, a plurality of vibrating arms 105 and 112 may be provided.

実施形態1に係る加速度センサの1例を示し、(a)は正面図、(b)は(a)のH−H切断面を示す断面図。An example of the acceleration sensor which concerns on Embodiment 1 is shown, (a) is a front view, (b) is sectional drawing which shows the HH cut surface of (a). 実施形態1の変形例1に係る加速度センサの構成を示す斜視図。FIG. 6 is a perspective view illustrating a configuration of an acceleration sensor according to a first modification of the first embodiment. 振動腕の総長さL1に対する貫通孔の長さL2の比と周波数変動量の関係について示すグラフ。The graph which shows about the relationship between the ratio of the length L2 of the through-hole with respect to the total length L1 of a vibrating arm, and the amount of frequency fluctuations. 実施形態1の変形例2に係る加速度センサを示す正面図。FIG. 6 is a front view showing an acceleration sensor according to a second modification of the first embodiment. 実施形態1の変形例3に係る加速度センサを示し、(a)は正面図、(b)は(a)のJ−J切断面を示す断面図。The acceleration sensor which concerns on the modification 3 of Embodiment 1 is shown, (a) is a front view, (b) is sectional drawing which shows the JJ cut surface of (a). 実施形態2に係る加速度センサを示す正面図。FIG. 6 is a front view showing an acceleration sensor according to a second embodiment. 実施形態3に係る加速度センサを示し、(a)は正面図、(b)は(a)のK−K切断面を示す断面図。The acceleration sensor which concerns on Embodiment 3 is shown, (a) is a front view, (b) is sectional drawing which shows the KK cut surface of (a). 実施形態4に係る加速度センサを示し、(a)は正面図、(b)は励振電極の構成を拡大して示す部分正面図。The acceleration sensor which concerns on Embodiment 4 is shown, (a) is a front view, (b) is a partial front view which expands and shows the structure of an excitation electrode. 実施形態5に係る振動体を示し、(a)は正面図、(b)は励振電極の構成を拡大して示す部分正面図。The vibrating body which concerns on Embodiment 5 is shown, (a) is a front view, (b) is a partial front view which expands and shows the structure of an excitation electrode. 実施形態6に係る加速度センサを示し、(a)は正面図、(b)は励振電極の構成を拡大して示す部分正面図。The acceleration sensor which concerns on Embodiment 6 is shown, (a) is a front view, (b) is a partial front view which expands and shows the structure of an excitation electrode. 実施形態7に係る加速度センサを示す正面図。FIG. 10 is a front view showing an acceleration sensor according to a seventh embodiment.

符号の説明Explanation of symbols

1…加速度センサ、10…振動体、20…基部、21…振動腕、22…貫通孔、23,
24…振動腕部、25…付加質量部、31〜34…励振手段としての励振電極。
DESCRIPTION OF SYMBOLS 1 ... Acceleration sensor, 10 ... Vibrating body, 20 ... Base part, 21 ... Vibrating arm, 22 ... Through-hole, 23,
24 ... vibrating arm part, 25 ... additional mass part, 31-34 ... excitation electrode as excitation means.

Claims (8)

基台に固定する基部と、前記基部から延出され所定の共振周波数にて平面方向に屈曲振
動をする梁状の振動腕と、からなる振動体であって、
前記振動腕が、幅方向中央部に厚さ方向に垂直に、且つ長手方向に開設される貫通孔に
よって分割された振動腕部と、分割された前記振動腕部の先端部を連結する付加質量部と
、前記振動腕部に設けられる励振手段と、を備え、
前記振動腕が、前記基部と前記付加質量部とにより擬似両端固定構造または片端固定構
造で支持され、
加速度が加えられたときの前記付加質量部の慣性効果による前記振動体の共振周波数変
化を検出することを特徴とする加速度センサ。
A vibrating body comprising: a base fixed to a base; and a beam-like vibrating arm extending from the base and bending-vibrating in a plane direction at a predetermined resonance frequency,
The vibrating arm is connected to a vibrating arm portion divided by a through-hole opened in the longitudinal direction in the width direction at a center portion in the width direction and an additional mass connecting the tip portion of the divided vibrating arm portion. And an excitation means provided on the vibrating arm portion,
The vibrating arm is supported by the base and the additional mass portion in a pseudo-both fixed structure or a one-end fixed structure,
An acceleration sensor for detecting a change in resonance frequency of the vibrating body due to an inertial effect of the additional mass portion when acceleration is applied.
請求項1に記載の加速度センサにおいて、
前記基部と、前記振動腕と、前記付加質量部と、からなる振動体が2組設けられ、
2組の前記付加質量部を共通付加質量部とし、前記共通付加質量部の重心位置に対して
点対称となるように2組の前記振動体が直線状に連結されていることを特徴とする加速度
センサ。
The acceleration sensor according to claim 1,
Two sets of vibrating bodies comprising the base, the vibrating arm, and the additional mass portion are provided,
Two sets of the additional mass portions are common additional mass portions, and the two sets of the vibrating bodies are linearly connected so as to be point-symmetric with respect to the center of gravity of the common additional mass portion. Acceleration sensor.
基台に固定する基部と、前記基部から平行に延出され所定の共振周波数にて平面方向に
屈曲振動をする梁状の複数の振動腕と、からなる振動体であって、
複数の前記振動腕それぞれの幅方向中央部に振動方向に対して垂直に、且つ長手方向に
開設される少なくとも一つの貫通孔と、
複数の前記振動腕の先端部を連結する付加質量部と、
複数の前記振動腕それぞれの両側側面と、前記貫通孔内部側面とに設けられる励振電極
と、を備え、
加速度が加えられたときの前記付加質量部の慣性効果による前記振動体の共振周波数変
化を検出することを特徴とする加速度センサ。
A vibrating body comprising a base fixed to a base and a plurality of beam-like vibrating arms extending in parallel from the base and bending-vibrating in a plane direction at a predetermined resonance frequency,
At least one through-hole formed in the longitudinal direction perpendicular to the vibration direction in the widthwise center of each of the plurality of vibrating arms;
An additional mass portion that connects the tip portions of the plurality of vibrating arms;
Exciting electrodes provided on both side surfaces of each of the plurality of vibrating arms and the inner side surface of the through hole,
An acceleration sensor for detecting a change in resonance frequency of the vibrating body due to an inertial effect of the additional mass portion when acceleration is applied.
請求項3に記載の加速度センサにおいて、
前記貫通孔が、少なくとも複数の前記振動腕と前記基部との連結部近傍に設けられてい
ることを特徴とする加速度センサ。
The acceleration sensor according to claim 3,
The acceleration sensor, wherein the through hole is provided in the vicinity of a connecting portion between at least a plurality of the vibrating arms and the base.
請求項3に記載の加速度センサにおいて、
前記貫通孔が、複数の前記振動腕に前記基部との連結部近傍と、前記付加質量部との連
結部近傍と、長手方向中央部と、に開設されていることを特徴とする加速度センサ。
The acceleration sensor according to claim 3,
The acceleration sensor according to claim 1, wherein the through-hole is formed in a plurality of the vibrating arms in the vicinity of a connection portion with the base portion, in the vicinity of a connection portion with the additional mass portion, and in a central portion in the longitudinal direction.
請求項3に記載の加速度センサにおいて、
前記基部と、前記貫通孔が開設された複数の前記振動腕と、前記付加質量部とからなる
振動体が2組設けられ、
2組の前記付加質量部を共通付加質量部とし、前記共通付加質量部の重心位置に対して
点対称となるように2組の前記振動体が直線状に連結されていることを特徴とする加速度
センサ。
The acceleration sensor according to claim 3,
Two sets of vibrating bodies each including the base, the plurality of vibrating arms having the through-holes, and the additional mass portion are provided,
Two sets of the additional mass portions are common additional mass portions, and the two sets of the vibrating bodies are linearly connected so as to be point-symmetric with respect to the center of gravity of the common additional mass portion. Acceleration sensor.
請求項1ないし請求項6のいずれか一項に記載の加速度センサにおいて、
前記振動体が水晶からなることを特徴とする加速度センサ。
The acceleration sensor according to any one of claims 1 to 6,
An acceleration sensor, wherein the vibrating body is made of quartz.
請求項1ないし請求項6のいずれか一項に記載の加速度センサにおいて、
前記振動体が恒弾性材料からなり、前記振動腕の側面に圧電素子膜が形成されているこ
とを特徴とする加速度センサ。
The acceleration sensor according to any one of claims 1 to 6,
An acceleration sensor, wherein the vibrating body is made of a constant elastic material, and a piezoelectric element film is formed on a side surface of the vibrating arm.
JP2008253520A 2006-10-13 2008-09-30 Acceleration sensor Withdrawn JP2009042240A (en)

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JP2008209388A (en) 2008-09-11

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