JP4796805B2 - Inertial sensor element - Google Patents

Inertial sensor element Download PDF

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JP4796805B2
JP4796805B2 JP2005249574A JP2005249574A JP4796805B2 JP 4796805 B2 JP4796805 B2 JP 4796805B2 JP 2005249574 A JP2005249574 A JP 2005249574A JP 2005249574 A JP2005249574 A JP 2005249574A JP 4796805 B2 JP4796805 B2 JP 4796805B2
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JP2007064746A (en
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良太 河合
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Kyocera Crystal Device Corp
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Description

本発明は、慣性センサ素子に関する。   The present invention relates to an inertial sensor element.

一般に、慣性センサ素子の形状としてＨ型の形状となる構造（以下、「Ｈ型構造」という。）のものが知られている。
図４に示すように、Ｈ型構造の慣性センサ素子２００は、基部２１０と、この基部２１０から延出する一対の励振用腕部２２０と、この励振用腕部２２０とは反対側に当該基部２１０から延出する一対の検出用腕部２３０とから構成され、当該検出用腕部２３０の幅ＪＷＡが励振用腕部２２０の幅ＪＷＢより広く形成されている。この基部２１０にはパッケージに固定するための支持部２４０が一対の検出用腕部２３０の間に設けられている（例えば、特許文献１参照）。 In general, an inertia sensor element having an H-shaped structure (hereinafter referred to as “H-shaped structure”) is known.
As shown in FIG. 4, the inertial sensor element 200 having an H-shaped structure includes a base 210, a pair of excitation arms 220 extending from the base 210, and the base on the opposite side of the excitation arms 220. The detection arm portion 230 extends from the pair 210, and the width JWA of the detection arm portion 230 is wider than the width JWB of the excitation arm portion 220. The base portion 210 is provided with a support portion 240 for fixing to the package between a pair of detection arm portions 230 (see, for example, Patent Document 1).

この慣性センサ素子２００の励振用腕部２２０をＸＹ平面内の１次屈曲振動（励振モード）で振動させた場合、検出用腕部２３０が振動しないのが理想的である。これを実現するために、従来の慣性センサ素子２００は、検出用腕部２３０の幅ＪＷＡを励振用腕部２２０の幅ＪＷＢより広くしている。これにより、励振振動時における、励振用腕部２２０のＸＹ平面内の１次屈曲振動モード（励振モード）と検出用腕部２３０のＸＹ平面内の１次屈曲振動モードとのカップリングを避けつつ振動を基部２１０より下の方、つまり検出用腕部２３０と支持部２４０とへ伝播しないようにしている。言い換えれば、検出用腕部２３０の幅ＪＷＡが励振用腕部２２０の幅ＪＷＢより広く形成されるのは、励振モード動作時（無回転時）に検出用腕部２３０への振動の伝播（以下、「振動漏れ」という場合がある。）を抑える必要があるためである。   Ideally, when the excitation arm 220 of the inertial sensor element 200 is vibrated by primary bending vibration (excitation mode) in the XY plane, the detection arm 230 does not vibrate. In order to achieve this, in the conventional inertial sensor element 200, the width JWA of the detection arm 230 is made wider than the width JWB of the excitation arm 220. This avoids coupling between the primary bending vibration mode (excitation mode) in the XY plane of the excitation arm 220 and the primary bending vibration mode in the XY plane of the detection arm 230 during excitation vibration. The vibration is prevented from propagating below the base 210, that is, to the detection arm 230 and the support 240. In other words, the width JWA of the detection arm portion 230 is formed wider than the width JWB of the excitation arm portion 220 because the vibration is propagated to the detection arm portion 230 during the excitation mode operation (no rotation) (hereinafter referred to as “resonance arm”). This may be referred to as “vibration leakage”).

また、１次屈曲振動の状態でＹ軸周りの回転角速度Ωが加わると、励振用腕部２２０はＺ軸方向にコリオリの力が加わり、Ｚ軸方向成分の振動が生じる。これによって、検出用腕部２３０も振動（歪み）が生じ、検出用腕部２３０に設けられた検出用電極（図示せず）により角速度の向きと大きさとを検出することができる。
特開２０００−１４６５９４号公報 In addition, when the rotational angular velocity Ω around the Y axis is applied in the state of the primary bending vibration, the excitation arm portion 220 applies Coriolis force in the Z axis direction, and vibration in the Z axis direction component occurs. As a result, vibration (distortion) is also generated in the detection arm 230, and the direction and magnitude of the angular velocity can be detected by a detection electrode (not shown) provided on the detection arm 230.
JP 2000-146594 A

しかしながら、従来のＨ型の慣性センサ素子２００では、等価回路における角速度検出モードの抵抗値Ｒ１が大きく、Ｑが小さかったために、角速度検出感度が小さかった。
また、コリオリの力が加わって、Ｚ軸方向に歪みが生じる際に、検出用腕部２３０の幅ＪＷＡが励振用腕部２２０の幅ＪＷＢより広いために、歪みが小さくなっていた。 However, in the conventional H-type inertial sensor element 200, since the resistance value R1 in the angular velocity detection mode in the equivalent circuit is large and Q is small, the angular velocity detection sensitivity is low.
Further, when distortion occurs in the Z-axis direction due to the Coriolis force, the width JWA of the detection arm 230 is wider than the width JWB of the excitation arm 220, and thus the distortion is small.

そこで、本発明では、前記した問題を解決し、精度良く角速度を検出する慣性センサ素子を提供することを課題とする。   Therefore, an object of the present invention is to provide an inertial sensor element that solves the above-described problems and accurately detects an angular velocity.

前記課題を解決するため、本発明は、圧電素子からなり、基部と、当該基部から延出する一対の励振用腕部と、当該励振用腕部と反対側に当該基部から延出する一対の検出用腕部とを備え、前記各励振用腕部が、前記基部側から離れる方向に幅が狭くなるように形成される励振テーパ部と、当該励振テーパ部側から所定の幅で形成される励振定幅部とを備え、前記各検出用腕部が、前記基部側から離れる方向に幅が狭くなるように形成される第一検出テーパ部と、当該第一検出テーパ部側から所定の幅で形成される第一検出定幅部と、当該第一検出定幅部側から離れる方向に幅が狭くなるように形成される第二検出テーパ部と、当該第二検出テーパ部側から所定の幅で形成される第二検出定幅部とを備え、前記第二検出定幅部の幅が、前記第一検出定幅部の幅より狭く、かつ、前記励振定幅部の幅より狭く形成され、前記第一検出定幅部の幅が、前記励振定幅部の幅の２倍以上広く形成されて構成されることを特徴とする。
In order to solve the above problems, the present invention comprises a piezoelectric element, a base, a pair of excitation arms extending from the base, and a pair of extensions extending from the base opposite to the excitation arms. Each of the excitation arm portions is formed with a predetermined width from the excitation taper portion side, and an excitation taper portion formed to have a width narrowing in a direction away from the base side. And a predetermined width from the first detection taper portion side. The first detection taper portion is formed so that the width of each detection arm portion becomes narrower in a direction away from the base side. A first detection constant width portion formed by the first detection constant width portion, a second detection taper portion formed so as to narrow in a direction away from the first detection constant width portion side, and a predetermined value from the second detection taper portion side. and a second detector constant width portion formed in a width, the width of the second detector constant width portion, the first Narrower than the width of the detector constant width portion, and the formed narrower than the width of the excitation constant width portion, constituting the width of the first detector constant width portion, is more than twice wider the width of the excitation of constant width portion It is characterized by being.

また、本発明は、前記第二検出定幅部の長さと前記励振定幅部の長さとの比が−１％〜＋１％となるように形成されても良い。   Further, the present invention may be formed such that a ratio between the length of the second detection constant width portion and the length of the excitation constant width portion is −1% to + 1%.

このような慣性センサ素子によれば、精度よく角速度を検出することができる。   According to such an inertial sensor element, the angular velocity can be detected with high accuracy.

次に、本発明を実施するための最良の形態（以下、「実施形態」という。）について、適宜図面を参照しながら詳細に説明する。図１は、本発明に係る慣性センサ素子の一例を示す図である。図２（ａ）は図１のＡ−Ａ部端面図であり、図２（ｂ）は図１のＢ−Ｂ端面図である。
なお、本実施形態において、圧電素子を水晶として説明する。また、厚みは、素子全体で所定の厚さで一定となっている場合について説明する。 Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the drawings as appropriate. FIG. 1 is a diagram showing an example of an inertial sensor element according to the present invention. 2A is an end view taken along the line AA in FIG. 1, and FIG. 2B is an end view taken along the line BB in FIG.
In the present embodiment, the piezoelectric element is described as a crystal. The case where the thickness is constant at a predetermined thickness throughout the element will be described.

図１に示すように、本発明に係る慣性センサ素子１００は、Ｘ´軸に沿って長辺を有する矩形形状の基部１０と、この基部１０から延出し、Ｙ´軸に沿って形成される一対の励振用腕部２０と、この励振用腕部２０とは反対側に基部１０から延出する検出用腕部３０とから主に構成されている。   As shown in FIG. 1, an inertial sensor element 100 according to the present invention is formed along a Y ′ axis and a rectangular base 10 having a long side along the X ′ axis, and extending from the base 10. It is mainly comprised from a pair of excitation arm part 20 and the detection arm part 30 extended from the base 10 on the opposite side to this excitation arm part 20. FIG.

なお、励振用腕部２０には励振用電極（図示せず）が形成され、図２に示すように、検出用腕部３０には検出用電極Ｋが形成されている。これにより、Ｘ´Ｙ´平面内の１次屈曲振動の状態（以下、「励振時」という。）でＹ´軸周りの回転角速度Ωが加わると、励振用腕部２０にコリオリの力がＺ´軸方向に加わってＺ´軸方向成分の振動が生じる。すると、検出用腕部３０も振動（歪み）が生じ、検出用腕部３０に設けられた検出用電極により角速度の向きと大きさとを検出することができる。   An excitation electrode (not shown) is formed on the excitation arm 20, and a detection electrode K is formed on the detection arm 30 as shown in FIG. As a result, when a rotational angular velocity Ω around the Y ′ axis is applied in a state of primary bending vibration in the X′Y ′ plane (hereinafter referred to as “excitation”), Coriolis force is applied to the excitation arm 20. In addition to the 'axis direction, vibration of the Z' axis direction component occurs. Then, vibration (distortion) is also generated in the detection arm 30, and the direction and magnitude of the angular velocity can be detected by the detection electrode provided on the detection arm 30.

基部１０は、矩形形状となっており、Ｘ´軸に沿う長辺側に励振用腕部２０及び検出用腕部３０が延出するようになっている。また、一対の検出用腕部の間に支持部４０を設けられており、パッケージ（図示せず）に固定できるようになっている。   The base portion 10 has a rectangular shape, and the excitation arm portion 20 and the detection arm portion 30 extend to the long side along the X ′ axis. In addition, a support portion 40 is provided between the pair of detection arm portions so that it can be fixed to a package (not shown).

一対の励振用腕部２０，２０は、それぞれ励振テーパ部２１と励振定幅部２２とから構成され、それぞれが所定の間隔をあけて、前記支持部４０とは反対側となる基部１０の長辺側から互いに平行となるようにＹ´軸に沿って延出している。   The pair of excitation arms 20, 20 are each composed of an excitation taper portion 21 and an excitation constant width portion 22, each of which is a length of the base portion 10 opposite to the support portion 40 with a predetermined interval therebetween. It extends along the Y ′ axis so as to be parallel to each other from the side.

励振テーパ部２１は、基部１０から延出しており、当該基部１０から離れる方向に幅が狭くなるように形成されている。
なお、本実施形態では、この励振テーパ部２１は、幅が狭くなる変化率を２段階に分けて形成されている。つまり、励振テーパ部２１のテーパとなる辺が、基部１０の長辺に対して緩やかな傾斜となる部分と、急な傾斜となる部分とからなり、基部１０の長辺に対して緩やかな傾斜となる部分が基部１０側に位置するようになっている。 The excitation taper portion 21 extends from the base portion 10 and is formed to have a narrow width in a direction away from the base portion 10.
In the present embodiment, the excitation taper portion 21 is formed by dividing the change rate at which the width becomes narrow into two stages. In other words, the taper side of the excitation taper portion 21 is composed of a portion having a gentle slope with respect to the long side of the base portion 10 and a portion having a steep slope, and a gentle slope with respect to the long side of the base portion 10. The part which becomes is located on the base 10 side.

励振定幅部２２は、励振テーパ部２１の幅が狭くなっている側の端部から所定の幅Ｗ３でかつ所定の長さＬ３で形成されている。   The excitation constant width portion 22 is formed with a predetermined width W3 and a predetermined length L3 from an end portion on the side where the width of the excitation taper portion 21 is narrowed.

一対の検出用腕部３０，３０は、それぞれ第一検出テーパ部３１，第一検出定幅部３２，第二検出テーパ部３３，第二検出定幅部３４から構成され、所定の間隔をあけて、前記支持部４０を間に挟んで、前記励振用腕部２０とは反対側となる基部１０の長辺側から互いに平行となるようにＹ´軸に沿って延出している。   The pair of detection arm portions 30 and 30 includes a first detection taper portion 31, a first detection constant width portion 32, a second detection taper portion 33, and a second detection constant width portion 34, respectively, with a predetermined interval. Then, with the support portion 40 in between, the Y portion extends from the long side of the base portion 10 opposite to the excitation arm portion 20 so as to be parallel to each other.

第一検出テーパ部３１は、基部１０から延出しており、当該基部１０から離れる方向に幅が狭くなるように形成されている。
なお、前記励振テーパ部２１と同様に、この第一検出テーパ部３１は、幅が狭くなる変化率を２段階に分けて形成されている。また、第二検出テーパ部３３も前記励振テーパ部２１と同様に幅が狭くなる変化率を２段階に分けて形成されている。 The first detection taper portion 31 extends from the base portion 10 and is formed to have a narrow width in a direction away from the base portion 10.
Similar to the excitation taper portion 21, the first detection taper portion 31 is formed by dividing the rate of change in width into two stages. Similarly to the excitation taper portion 21, the second detection taper portion 33 is also formed by dividing the change rate of the width into two stages.

第一検出定幅部３２は、第一検出テーパ部３１の幅が狭くなっている側の端部から所定の幅Ｗ１でかつ所定の長さＬ１で形成され、励振用腕部２０からの振動の伝播を防ぐ役割を果たす。   The first detection constant width portion 32 is formed with a predetermined width W1 and a predetermined length L1 from an end portion on the side where the width of the first detection taper portion 31 is narrow, and vibration from the excitation arm portion 20 Plays a role in preventing the propagation of

ここで、第一検出定幅部３２の幅Ｗ１は、励振用腕部２０の励振定幅部２２の幅Ｗ３の２倍以上となっている。
また、第一検出定幅部３２の長さＬ１は、励振用腕部２０の励振定幅部２２の長さＬ３の３分の１となっている。 Here, the width W1 of the first detection constant width portion 32 is at least twice the width W3 of the excitation constant width portion 22 of the excitation arm portion 20.
Further, the length L1 of the first detection constant width portion 32 is one third of the length L3 of the excitation constant width portion 22 of the excitation arm portion 20.

つまり、第一検出定幅部３２の長さＬ１が励振定幅部２２の長さＬ３の３分の１とならない場合、第一検出定幅部３２の幅Ｗ１が励振定幅部２２の幅Ｗ３の２倍より小さいと、励振時の振動を検出用腕部３０への伝播が大きく（十分に抑えきれず）、振動漏れが増大してしまう。したがって、第一検出定幅部３２を前記のごとく形成することにより、励振時における振動漏れを抑制できるため、精度良く角速度を検出することができる。   That is, when the length L1 of the first detection constant width portion 32 is not one third of the length L3 of the excitation constant width portion 22, the width W1 of the first detection constant width portion 32 is the width of the excitation constant width portion 22. If it is smaller than twice W3, the vibration during excitation is greatly propagated to the detection arm 30 (it cannot be sufficiently suppressed), and vibration leakage increases. Therefore, by forming the first detection constant width portion 32 as described above, vibration leakage at the time of excitation can be suppressed, so that the angular velocity can be detected with high accuracy.

第二検出テーパ部３３は、第一検出定幅部３２の端部に、基部１０から離れる方向に幅が狭くなるように形成されている。   The second detection taper portion 33 is formed at the end of the first detection constant width portion 32 so that the width is narrowed in the direction away from the base portion 10.

第二検出定幅部３４は、第二検出テーパ部３３の幅が狭くなっている側の端部から所定の幅Ｗ２でかつ所定の長さＬ２で形成され、角速度検出感度を向上させる役割を果たす。   The second detection constant width portion 34 is formed with a predetermined width W2 and a predetermined length L2 from the end on the side where the width of the second detection taper portion 33 is narrow, and plays a role of improving the angular velocity detection sensitivity. Fulfill.

ここで、第二検出定幅部３４の幅Ｗ２は、第一検出定幅部３２の幅Ｗ１より狭く、かつ、励振用腕部２０の励振定幅部２２の幅Ｗ３より狭く形成される。
また、第二検出定幅部３４の長さＬ２は、当該第二検出定幅部３４の長さＬ２と励振用腕部２０の励振定幅部２２の長さＬ３との比が＋１％となるように形成されている。 Here, the width W2 of the second detection constant width portion 34 is formed to be narrower than the width W1 of the first detection constant width portion 32 and narrower than the width W3 of the excitation constant width portion 22 of the excitation arm portion 20.
The length L2 of the second detection constant width portion 34 is such that the ratio of the length L2 of the second detection constant width portion 34 and the length L3 of the excitation constant width portion 22 of the excitation arm portion 20 is + 1%. It is formed to become.

このように、第二検出定幅部３４が当該第二検出定幅部３４の長さＬ２と励振用腕部２０の励振定幅部２２の長さＬ３との比が±１％となるように形成されることで、検出振動時において、振動の節が基部１０中央部に位置するので、角速度の誤検出がなくなり、また、検出誤差を小さくすることができる。また、第二検出定幅部３４が当該第二検出定幅部３４の長さＬ２と励振用腕部２０の励振定幅部２２の長さＬ３との比が±１％を超えて形成されると、振動の節が基部１０中央部に位置しなくなり、振動バランスが悪くなる。
なお、このように、振動の節が基部１０にある場合を振動バランスが良いという。 Thus, the second detection constant width portion 34 has a ratio of ± 1% between the length L2 of the second detection constant width portion 34 and the length L3 of the excitation constant width portion 22 of the excitation arm portion 20. As a result, the vibration node is located at the center of the base 10 during detection vibration, so that erroneous detection of angular velocity is eliminated and detection error can be reduced. The second detection constant width portion 34 is formed so that the ratio of the length L2 of the second detection constant width portion 34 and the length L3 of the excitation constant width portion 22 of the excitation arm portion 20 exceeds ± 1%. Then, the vibration node is not positioned at the center of the base 10 and the vibration balance is deteriorated.
It should be noted that the vibration balance is good when the node of vibration is in the base 10 as described above.

このような慣性センサ素子１００において、第二検出定幅部３４の幅Ｗ２が励振定幅部２２の幅Ｗ３より狭いために、第二検出定幅部３４の歪みが大きくなり、また、この歪みが第一検出定幅部３２に応力を加えるため、第一検出定幅部３２に歪が生じる。   In such an inertial sensor element 100, since the width W2 of the second detection constant width portion 34 is narrower than the width W3 of the excitation constant width portion 22, the distortion of the second detection constant width portion 34 is increased. However, since stress is applied to the first detection constant width portion 32, the first detection constant width portion 32 is distorted.

したがって、第一検出テーパ部３１側の第一検出定幅部３２の端部部分と、第二検出テーパ部３３側の第二検出定幅部３４の端部部分とに電荷が集中しやすくなるので、図２（ａ）及び図２（ｂ）に示すように、検出電極Ｋを第一検出定幅部３２と第二検出定幅部３４とに設ければ、検出電極の有効電極面積が大きくなり、角速度検出感度を向上させることができる。
なお、検出電極Ｋは、厚さ方向に異なる極性を並べつつ、幅方向に異なる極性を対向させて設けられている。 Accordingly, electric charges are likely to concentrate on the end portion of the first detection constant width portion 32 on the first detection taper portion 31 side and the end portion of the second detection constant width portion 34 on the second detection taper portion 33 side. Therefore, as shown in FIGS. 2A and 2B, if the detection electrode K is provided in the first detection constant width portion 32 and the second detection constant width portion 34, the effective electrode area of the detection electrode is increased. This increases the angular velocity detection sensitivity.
The detection electrode K is provided with different polarities facing each other in the width direction while arranging different polarities in the thickness direction.

ここで、長さＬ１と幅Ｗ１となる第一検出定幅部３２と、長さＬ２と幅Ｗ２となる第二検出定幅部３４と、長さＬ３と幅Ｗ３となる励振定幅部２２の各周波数について説明する。図３は、励振用定幅部の長さと第二検出用幅部の長さとの比に対する検出振動時の基部中心部の変位の一例を示すグラフである。   Here, the first detection constant width portion 32 having the length L1 and the width W1, the second detection constant width portion 34 having the length L2 and the width W2, and the excitation constant width portion 22 having the length L3 and the width W3. Each frequency will be described. FIG. 3 is a graph showing an example of the displacement of the central portion of the base during detection vibration with respect to the ratio of the length of the excitation constant width portion and the length of the second detection width portion.

まず、励振時の励振定幅部２２の周波数Ｆ３は、（１）式で現される。
Ｆ３＝Ｋｆ×λ２×Ｗ３／（Ｌ３）２ ・・・ （１）
ここで、Ｋｆは周波数定数であり、λは、境界条件である。
また、励振時の第一検出定幅部３２の周波数Ｆ１は、（２）式で現される。
Ｆ１＝Ｋｆ×λ２×Ｗ１／（Ｌ１）２ ・・・ （２）
また、励振時の第二検出定幅部３４の周波数Ｆ２は、（３）式で現される。
Ｆ２＝Ｋｆ×λ２×Ｗ２／（Ｌ２）２ ・・・ （３） First, the frequency F3 of the excitation constant width portion 22 at the time of excitation is expressed by equation (1).
F3 = Kf × λ 2 × W3 / (L3) 2 (1)
Here, Kf is a frequency constant, and λ is a boundary condition.
Further, the frequency F1 of the first detection constant width portion 32 at the time of excitation is expressed by the equation (2).
F1 = Kf × λ 2 × W1 / (L1) 2 (2)
Moreover, the frequency F2 of the second detection constant width part 34 at the time of excitation is represented by (3) Formula.
F2 = Kf × λ 2 × W2 / (L2) 2 (3)

このとき、励振時に第一検出定幅部３２と第二検出定幅部３４とが振動しにくくなるようにする場合は、検出振動時の第一検出定幅部３２の振動Ｆ１（検出振動時の第二検出定幅部３４の振動Ｆ２）と励振時の励振定幅部２２の振動Ｆ３とが異なるようにする。つまり、この第一検出定幅部３２の振動Ｆ１（検出振動時の第二検出定幅部３４の振動Ｆ２）と励振時の励振定幅部２２の振動Ｆ３との差が大きくなるにつれて励振時に第一検出定幅部３２と第二検出定幅部３４とが振動しにくくなる。   At this time, when making it difficult for the first detection constant width portion 32 and the second detection constant width portion 34 to vibrate during excitation, the vibration F1 of the first detection constant width portion 32 during detection vibration (when detecting vibration) The vibration F2) of the second detection constant width portion 34 is different from the vibration F3 of the excitation constant width portion 22 during excitation. That is, during the excitation as the difference between the vibration F1 of the first detection constant width portion 32 (vibration F2 of the second detection constant width portion 34 during detection vibration) and the vibration F3 of the excitation constant width portion 22 during excitation increases. The first detection constant width portion 32 and the second detection constant width portion 34 are less likely to vibrate.

したがって、第一検出定幅部３２の幅Ｗ１が励振定幅部２２の幅Ｗ３の２倍となっており、第一検出定幅部３２の長さＬ１が励振定幅部２２の長さＬ３の３分の１倍となっているので、励振時における第一検出定幅部３２の周波数は励振定幅部２２と異なり、振動の伝播による影響が従来に比べて小さくなる。   Therefore, the width W1 of the first detection constant width portion 32 is twice the width W3 of the excitation constant width portion 22, and the length L1 of the first detection constant width portion 32 is the length L3 of the excitation constant width portion 22. Therefore, the frequency of the first detection constant width portion 32 at the time of excitation is different from that of the excitation constant width portion 22, and the influence of vibration propagation is smaller than that of the conventional case.

また、第二検出定幅部３４の幅Ｗ２が励振定幅部２２の幅Ｗ３の２分の１倍となっており、第一検出定幅部３４の長さＬ１が励振定幅部２２の長さＬ３の＋１％分長くなっているので、励振時における第一検出定幅部３２の周波数は励振定幅部２２と異なり、振動の伝播による影響が従来に比べて小さくなる。   Further, the width W2 of the second detection constant width portion 34 is a half of the width W3 of the excitation constant width portion 22, and the length L1 of the first detection constant width portion 34 is equal to that of the excitation constant width portion 22. Since the length is increased by + 1% of the length L3, the frequency of the first detection constant width portion 32 at the time of excitation is different from that of the excitation constant width portion 22, and the influence of vibration propagation is smaller than in the conventional case.

また、検出振動時の励振定幅部２２の周波数Ｆｓ３は、（４）式で現される。
Ｆｓ３＝Ｋｆ×λ２×ｔ／（Ｌ３）２ ・・・ （４）
ここで、ｔは、厚さである。
また、検出振動時の第一検出定幅部３２の周波数Ｆｓ１は、（５）式で現される。
Ｆｓ１＝Ｋｆ×λ２×ｔ／（Ｌ１）２ ・・・ （５）
また、検出振動時の第二検出定幅部３４の周波数Ｆｓ２は、（６）式で現される。
Ｆｓ２＝Ｋｆ×λ２×ｔ／（Ｌ２）２ ・・・ （６） Further, the frequency Fs3 of the excitation constant width portion 22 at the time of detected vibration is expressed by the equation (4).
Fs3 = Kf × λ 2 × t / (L3) 2 (4)
Here, t is the thickness.
Further, the frequency Fs1 of the first detection constant width portion 32 at the time of the detection vibration is expressed by Expression (5).
Fs1 = Kf × λ 2 × t / (L1) 2 (5)
Further, the frequency Fs2 of the second detection constant width portion 34 at the time of the detection vibration is expressed by Expression (6).
Fs2 = Kf × λ 2 × t / (L2) 2 (6)

検出振動時に、励振定幅部２２の周波数と第二検出定幅部３４の周波数とをカップリングさせる場合は、振動の節が基部１０にあるようにする。   When coupling the frequency of the excitation constant width portion 22 and the frequency of the second detection constant width portion 34 at the time of the detection vibration, the node of vibration is set to be in the base portion 10.

一例として、図３に示すように、第二検出定幅部３４の長さＬ２と励振定幅部２２の長さＬ３との比が±０．５％で形成される場合、検出振動時の基部１０中央部の変位がほぼ０となり、振動バランスが良い状態となっている。
したがって、第二検出定幅部３４の長さＬ２と励振定幅部２２の長さＬ３との比が±１％で形成されることで検出振動時の振動バランスが良くなり、精度良く角速度を検出することができる。 As an example, as shown in FIG. 3, when the ratio between the length L2 of the second detection constant width portion 34 and the length L3 of the excitation constant width portion 22 is formed at ± 0.5%, The displacement at the center of the base 10 is almost zero, and the vibration balance is good.
Therefore, since the ratio of the length L2 of the second detection constant width portion 34 and the length L3 of the excitation constant width portion 22 is formed at ± 1%, the vibration balance at the time of detection vibration is improved, and the angular velocity is accurately determined. Can be detected.

また、第一検出定幅部３２の長さＬ１は、励振定幅部２２の長さＬ３の３分の１倍となっているので、検出振動時の第二検出定幅部３４の周波数Ｆｓ２と励振定幅部２２の周波数Ｆｓ３とのカップリングに影響することがない。   In addition, since the length L1 of the first detection constant width portion 32 is one third of the length L3 of the excitation constant width portion 22, the frequency Fs2 of the second detection constant width portion 34 during detection vibration. And the frequency Fs3 of the excitation constant width portion 22 are not affected.

このように慣性センサ素子１００を構成したことにより、励振時に検出用腕部３０が振動しにくくなるので、誤検出等をなくすことができる。
また、検出振動時に検出用腕部３０が励振用腕部２０の振動とカップリングすることができるので、振動漏れが増大し、精度良く角速度を検出することができる。 By configuring the inertial sensor element 100 in this manner, the detection arm 30 is less likely to vibrate during excitation, so that erroneous detection and the like can be eliminated.
Further, since the detection arm 30 can be coupled with the vibration of the excitation arm 20 during the detection vibration, vibration leakage increases, and the angular velocity can be detected with high accuracy.

なお、本発明に係る慣性センサ素子１００の支持部４０も含めた最大の長さＬの一例としては、例えば、３．５ｍｍであり、また、本発明に係る慣性センサ素子１００の支持部４０も含めた最大の幅Ｗの一例としては、例えば、１ｍｍとなっている。したがって、このような慣性センサ素子１００を収納可能な、例えば、５０ｍｍ×３２ｍｍサイズ以下のパッケージが適用可能となる。   An example of the maximum length L including the support portion 40 of the inertial sensor element 100 according to the present invention is, for example, 3.5 mm, and the support portion 40 of the inertial sensor element 100 according to the present invention is also included. An example of the included maximum width W is, for example, 1 mm. Therefore, for example, a package having a size of 50 mm × 32 mm or less that can accommodate such inertial sensor element 100 can be applied.

以上、本発明の実施形態について説明したが、本発明は前記実施形態には限定されない。例えば、本実施形態では、圧電素子を水晶として説明したがこれに限定されるものではなく、ニオブ酸リチウム、タンタル酸リチウム等の圧電効果のある材質を適宜用いることができる。   As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, in the present embodiment, the piezoelectric element is described as a quartz crystal, but the present invention is not limited to this, and a material having a piezoelectric effect such as lithium niobate or lithium tantalate can be used as appropriate.

本発明に係る慣性センサ素子の一例を示す図である。It is a figure which shows an example of the inertial sensor element which concerns on this invention. （ａ）は図１のＡ−Ａ部端面図であり、（ｂ）は図１のＢ−Ｂ端面図である。(A) is the AA section end elevation of Drawing 1, (b) is the BB end elevation of Drawing 1. 励振用定幅部の長さと第二検出用幅部の長さとの比に対する検出振動時の基部中心部の変位の一例を示すグラフである。It is a graph which shows an example of the displacement of the base center part at the time of a detection vibration with respect to the ratio of the length of the constant width part for excitation, and the length of the width part for 2nd detection. 従来の慣性センサ素子を示す図である。It is a figure which shows the conventional inertial sensor element.

符号の説明Explanation of symbols

１００ 慣性センサ素子
１０ 基部
２０ 励振用腕部
２１ 励振テーパ部
２２ 励振定幅部
３０ 検出用腕部
３１ 第一検出テーパ部
３２ 第一検出定幅部
３３ 第二検出テーパ部
３４ 第二検出定幅部
Ｋ 検出電極
Ｗ１，Ｗ２，Ｗ３ 幅
Ｌ１，Ｌ２，Ｌ３ 長さ DESCRIPTION OF SYMBOLS 100 Inertial sensor element 10 Base 20 Excitation arm part 21 Excitation taper part 22 Excitation taper part 30 Detection arm part 31 1st detection taper part 32 1st detection constant width part 33 2nd detection taper part 34 2nd detection constant width Part K Detection electrode W1, W2, W3 Width L1, L2, L3 Length

Claims (2)

圧電素子からなり、基部と、当該基部から延出する一対の励振用腕部と、当該励振用腕部と反対側に当該基部から延出する一対の検出用腕部とを備え、
前記各励振用腕部が、前記基部側から離れる方向に幅が狭くなるように形成される励振テーパ部と、
当該励振テーパ部側から所定の幅で形成される励振定幅部とを備え、
前記各検出用腕部が、
前記基部側から離れる方向に幅が狭くなるように形成される第一検出テーパ部と、
当該第一検出テーパ部側から所定の幅で形成される第一検出定幅部と、
当該第一検出定幅部側から離れる方向に幅が狭くなるように形成される第二検出テーパ部と、
当該第二検出テーパ部側から所定の幅で形成される第二検出定幅部とを備え、
前記第二検出定幅部の幅が、前記第一検出定幅部の幅より狭く、かつ、前記励振定幅部の幅より狭く形成され、
前記第一検出定幅部の幅が、前記励振定幅部の幅の２倍以上広く形成されて構成されることを特徴とする慣性センサ素子。 A piezoelectric element, comprising a base, a pair of excitation arms extending from the base, and a pair of detection arms extending from the base on the opposite side of the excitation arm,
The excitation taper portion formed so that the width of each of the excitation arm portions becomes narrower in a direction away from the base side,
An excitation constant width portion formed with a predetermined width from the excitation taper portion side,
Each of the detection arms is
A first detection taper portion formed so as to be narrow in a direction away from the base side;
A first detection constant width portion formed with a predetermined width from the first detection taper portion side;
A second detection taper portion formed so that the width becomes narrower in a direction away from the first detection constant width portion side;
A second detection constant width portion formed with a predetermined width from the second detection taper portion side,
The width of the second detection constant width portion is narrower than the width of the first detection constant width portion, and narrower than the width of the excitation constant width portion,
The inertial sensor element, wherein the first detection constant width portion is formed to have a width that is at least twice as wide as the excitation constant width portion . 前記第二検出定幅部の長さと前記励振定幅部の長さとの比が−１％〜＋１％となるように形成されることを特徴とする請求項１に記載の慣性センサ素子。 2. The inertial sensor element according to claim 1, wherein a ratio of a length of the second detection constant width portion and a length of the excitation constant width portion is −1% to + 1%.
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