JP2010210430A

JP2010210430A - Acceleration sensor

Info

Publication number: JP2010210430A
Application number: JP2009056955A
Authority: JP
Inventors: Hitoshi Yoshida; 仁吉田; Nobuyuki Ibara; 伸行茨; Masafumi Okada; 全史岡田; Hideki Ueda; 英喜上田; Takashi Mori; 岳志森
Original assignee: Panasonic Electric Works Co Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2009-03-10
Filing date: 2009-03-10
Publication date: 2010-09-24

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acceleration sensor that prevents the damage of a beam when excessive acceleration exceeding a measuring range is given. <P>SOLUTION: The acceleration sensor includes a first movable electrode 40 formed in a substantially square shape in a plane view, a first frame 30 which is formed in a substantially square shape in the plane view and surrounds the first movable electrode 40 with a prescribed space left in between, and a pair of first beams 5a and 5b which couples the first movable electrode 40 with the first frame 30 supports the first movable electrode 40 so that it can rock in relation to the first frame 30. The first beams 5a and 5b are formed so that their shafts are positioned on a diagonal line of the first frame 30, and a pair of projecting pieces 30a formed in a substantially square shape in the plane view and projecting toward the first movable electrode 40 is formed integrally with the first frame 30, on the diagonal line of the first frame 30 intersecting the diagonal line at right angles. Recesses 40c each of which is opened on one side opposite to the first frame 30 are provided respectively in the thickness direction through the portions of the first movable part 40 which are opposed to the projecting pieces 30a, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、可動電極の揺動に伴う可動電極と固定電極との間の静電容量の変化に基づいて加速度を検出する静電容量型の加速度センサに関する。 The present invention relates to a capacitance-type acceleration sensor that detects acceleration based on a change in capacitance between a movable electrode and a fixed electrode accompanying the swing of the movable electrode.

従来から、平面視矩形状の可動電極と、可動電極の対向する２辺の略中央において可動電極を揺動自在に支持する１対のビーム部と、可動電極の表面において１対のビーム部を結ぶ直線を境界線とした一方側と他方側のそれぞれに対して所定の距離を空けて対向配置された固定電極とを備え、可動電極の揺動に伴う可動電極と固定電極との間の静電容量の変化を検出することで加速度を検出する静電容量型の加速度センサが知られている（例えば、特許文献１参照）。 Conventionally, a movable electrode having a rectangular shape in plan view, a pair of beam portions that swingably support the movable electrode at substantially the center of two opposite sides of the movable electrode, and a pair of beam portions on the surface of the movable electrode. A fixed electrode disposed opposite to each other with a predetermined distance from one side and the other side with a connecting straight line as a boundary line, and a static electrode between the movable electrode and the fixed electrode that accompanies the swinging of the movable electrode. A capacitance-type acceleration sensor that detects acceleration by detecting a change in capacitance is known (see, for example, Patent Document 1).

以下、このような加速度センサの従来例について図面を用いて説明する。尚、以下の説明では、図５における上下を上下方向と定めるものとする。また、センサチップ１の短手方向と平行な方向をｘ方向、センサチップ１の長手方向と平行な方向をｙ方向、ｘ方向及びｙ方向に互いに直交する方向をｚ方向と定めるものとする。この従来例は、図５に示すように、ＳＯＩ（Silicon on Insulator）基板で形成されたセンサチップ１が上部固定板２ａと下部固定板２ｂとで挟持された構成となっている。センサチップ１は、２つの平面視略矩形状の第１の枠部３０及び第２の枠部３１を有するフレーム部３と、枠部３０，３１の側壁部に対して隙間を空けて各枠部３０，３１に囲まれた空間に配設される平面視略矩形状の２つの第１の可動電極４０及び第２の可動電極４１と、各可動電極４０，４１上面の対向する２辺の略中央部と各枠部３０，３１の側壁部とを連結することにより各可動電極４０，４１をフレーム部３に対して揺動自在に支持する２対のビーム部５ａ〜５ｄとを備える。 Hereinafter, a conventional example of such an acceleration sensor will be described with reference to the drawings. In the following description, the vertical direction in FIG. 5 is defined as the vertical direction. In addition, a direction parallel to the short direction of the sensor chip 1 is defined as an x direction, a direction parallel to the longitudinal direction of the sensor chip 1 is defined as a y direction, and a direction orthogonal to the x direction and the y direction is defined as a z direction. In this conventional example, as shown in FIG. 5, a sensor chip 1 formed of an SOI (Silicon on Insulator) substrate is sandwiched between an upper fixing plate 2a and a lower fixing plate 2b. The sensor chip 1 includes a frame portion 3 having a first frame portion 30 and a second frame portion 31 that are substantially rectangular in plan view, and each frame with a gap between the side walls of the frame portions 30 and 31. The two first movable electrodes 40 and the second movable electrode 41 having a substantially rectangular shape in plan view disposed in a space surrounded by the portions 30 and 31, and two opposing sides of the upper surfaces of the movable electrodes 40 and 41. Two pairs of beam portions 5a to 5d that support the movable electrodes 40 and 41 so as to be swingable with respect to the frame portion 3 by connecting the substantially central portion and the side walls of the frame portions 30 and 31 are provided.

上部固定板２ａはガラス基板により形成され、図５に示すように、第１の可動電極４０と対向する下面には１対の第１のビーム部５ａ，５ｂを結ぶ直線を境界線として第１の固定電極２０ａ及び第２の固定電極２０ｂが設けられている。また、第２の可動電極４１と対向する下面には、１対の第２のビーム部５ｃ，５ｄを結ぶ直線を境界線として第３の固定電極２０ｃ及び第４の固定電極２０ｄが設けられている。各固定電極２０ａ〜２０ｄはアルミニウム系合金から形成されている。 The upper fixed plate 2a is formed of a glass substrate. As shown in FIG. 5, the lower surface facing the first movable electrode 40 has a straight line connecting a pair of first beam portions 5a and 5b as a boundary line. The fixed electrode 20a and the second fixed electrode 20b are provided. Further, on the lower surface facing the second movable electrode 41, a third fixed electrode 20c and a fourth fixed electrode 20d are provided with a straight line connecting the pair of second beam portions 5c and 5d as a boundary line. Yes. Each fixed electrode 20a-20d is formed from an aluminum-based alloy.

下部固定板２ｂは、上部固定板２ａと同様にガラス基板により形成され、図５，６に示すように、各可動電極４０，４１と間隔を空けて付着防止膜２３ａ，２３ｂが配設されている。付着防止膜２３ａ，２３ｂは各固定電極２０ａ〜２０ｄと同じ材料から成り、各可動電極４０，４１が動作時に下部固定板２ｂに付着するのを防止する。また、測定レンジを超える過大な加速度が加えられた場合には、付着防止膜２３ａ，２３ｂによって各可動電極４０，４１と下部固定板２ｂとが直接接触するのを防ぐことから衝撃緩和の効果を奏する。 The lower fixed plate 2b is formed of a glass substrate in the same manner as the upper fixed plate 2a. As shown in FIGS. 5 and 6, the anti-adhesion films 23a and 23b are disposed at a distance from the movable electrodes 40 and 41, respectively. Yes. The adhesion preventing films 23a and 23b are made of the same material as the fixed electrodes 20a to 20d, and prevent the movable electrodes 40 and 41 from adhering to the lower fixed plate 2b during operation. In addition, when excessive acceleration exceeding the measurement range is applied, the adhesion preventing films 23a and 23b prevent the movable electrodes 40 and 41 and the lower fixed plate 2b from coming into direct contact with each other. Play.

センサチップ１には、図５に示すように、第１の可動電極４０と各固定電極２０ａ，２０ｂとの間の静電容量Ｃ１，Ｃ２を各々検出する検出電極６ａ，６ｂと、第２の可動電極４１と各固定電極２０ｃ，２０ｄとの間の静電容量Ｃ３，Ｃ４を各々検出する検出電極６ｃ，６ｄと、接地電極７とが設けられている。上部固定板２ａの各検出電極６ａ〜６ｄ及び接地電極７と対向する部位にはスルーホール２１ａ〜２１ｄ，２２が貫設されており、当該スルーホール２１ａ〜２１ｄ，２２を介して各固定電極２０ａ〜２０ｄに各々接続された検出電極６ａ〜６ｄ、及び接地電極７の出力が取り出されるようになっている。また、検出電極６ａと検出電極６ｂとの間、検出電極６ｃと検出電極６ｄとの間、各検出電極６ａ〜６ｄとフレーム部３との間、各検出電極６ａ〜６ｄと各可動電極４０，４１との間には各々隙間が形成されている。このように構成することで、各検出電極６ａ〜６ｄが互いに電気的に絶縁されるので、各検出電極６ａ〜６ｄの寄生容量や電極間のクロストークを低減し、高精度な静電容量の検出を行うことができる。 As shown in FIG. 5, the sensor chip 1 includes detection electrodes 6a and 6b for detecting capacitances C1 and C2 between the first movable electrode 40 and the fixed electrodes 20a and 20b, respectively, and a second Detection electrodes 6c and 6d for detecting capacitances C3 and C4 between the movable electrode 41 and the fixed electrodes 20c and 20d, respectively, and a ground electrode 7 are provided. Through holes 21a to 21d and 22 are formed through portions of the upper fixed plate 2a facing the detection electrodes 6a to 6d and the ground electrode 7, and the fixed electrodes 20a are inserted through the through holes 21a to 21d and 22, respectively. The outputs of the detection electrodes 6a to 6d and the ground electrode 7 respectively connected to ˜20d are taken out. Moreover, between the detection electrode 6a and the detection electrode 6b, between the detection electrode 6c and the detection electrode 6d, between each detection electrode 6a-6d and the flame | frame part 3, each detection electrode 6a-6d and each movable electrode 40, A gap is formed between each of the terminals 41 and 41. With this configuration, the detection electrodes 6a to 6d are electrically insulated from each other, so that parasitic capacitance of the detection electrodes 6a to 6d and crosstalk between the electrodes are reduced, and high-accuracy capacitance can be obtained. Detection can be performed.

第１の可動電極４０の下面における１対の第１のビーム部５ａ，５ｂを結ぶ直線を境界線とした一方側には、図６に示すように、厚み寸法が前記他方側の厚み寸法よりも小さくなるように凹部４０ａが設けられている。同様に、第２の可動電極４１の下面における１対の第２のビーム５ｃ，５ｄを結ぶ直線を境界線とした一方側にも、図示しないが、厚み寸法が前記他方側の寸法よりも小さくなるように凹部４１ａが設けられている。何れの凹部４０ａ，４１ａも、図６に示すように、各可動電極４０，４１の重心位置Ｏとビーム部５ａ〜５ｄとが成す角度θが４５度となるように設けられている。このように構成することで、加速度が加えられた際にビーム部５ａ〜５ｄを軸とした回転モーメントが各可動電極４０，４１に発生し、ｘ方向及びｚ方向の検出感度が等価になる。尚、この従来例では、図５に示すように２つの加速度センサがｘｙ平面に配置され、一方の加速度センサが他方の加速度センサに対してｘｙ平面内で１８０度回転して配置されている。 On one side of the lower surface of the first movable electrode 40 with a straight line connecting the pair of first beam portions 5a and 5b as a boundary line, the thickness dimension is larger than the thickness dimension on the other side, as shown in FIG. A recess 40a is provided so as to be smaller. Similarly, on one side of the lower surface of the second movable electrode 41 with a straight line connecting the pair of second beams 5c and 5d as a boundary line, although not shown, the thickness dimension is smaller than the dimension on the other side. The recessed part 41a is provided so that it may become. As shown in FIG. 6, each of the recesses 40a and 41a is provided such that an angle θ formed by the center of gravity O of each movable electrode 40 and 41 and the beam portions 5a to 5d is 45 degrees. With this configuration, when acceleration is applied, a rotational moment about the beam portions 5a to 5d is generated in each of the movable electrodes 40 and 41, and the detection sensitivity in the x direction and the z direction becomes equivalent. In this conventional example, as shown in FIG. 5, two acceleration sensors are arranged on the xy plane, and one acceleration sensor is arranged 180 degrees rotated in the xy plane with respect to the other acceleration sensor.

各可動電極４０，４１の上部固定板２ａ及び下部固定板２ｂと対向する面には、図６に示すように（図６では第１の可動電極４０のみ図示）、シリコン又はシリコン酸化膜により形成された複数の突起部４０ｂが設けられている。このような突起部４０ｂを設けることにより、各可動電極４０，４１に測定レンジを超える過大な加速度が加えられた場合であっても、各可動電極４０，４１が対向する上部固定板２ａ及び下部固定板２ｂと直接衝突することがなく、センサチップ１の破損を防止することができる。尚、この従来例では各可動電極４０，４１の上部固定板２ａ及び下部固定板２ｂと対向する面に突起部４０ｂを設けているが、上部固定板２ａ及び下部固定板２ｂの各可動電極４０，４１と対向する面に突起部４０ｂを設けても構わない。 As shown in FIG. 6 (only the first movable electrode 40 is shown in FIG. 6), the surface of each movable electrode 40, 41 facing the upper fixed plate 2a and the lower fixed plate 2b is formed of silicon or a silicon oxide film. A plurality of protruding portions 40b are provided. By providing such a protrusion 40b, even if excessive acceleration exceeding the measurement range is applied to each movable electrode 40, 41, the upper fixed plate 2a and the lower portion facing each movable electrode 40, 41 are arranged. The sensor chip 1 can be prevented from being damaged without directly colliding with the fixing plate 2b. In this conventional example, the protrusions 40b are provided on the surfaces of the movable electrodes 40, 41 facing the upper fixed plate 2a and the lower fixed plate 2b. However, the movable electrodes 40 of the upper fixed plate 2a and the lower fixed plate 2b are provided. , 41 may be provided on the surface facing the projection 41b.

以下、上記従来例における加速度検出について説明する。先ず、ｘ方向における加速度の検出について説明する。第１の可動電極４０にｘ方向の加速度が加えられた場合、第１の可動電極４０と各固定電極２０ａ，２０ｂとの間の静電容量Ｃ１，Ｃ２は、それぞれ以下に示す数式で表される。尚、数式（１），（２）中のパラメータＣ０は、第１の可動電極４０にｘ方向の加速度が加えられていない状態における第１の可動電極４０と各固定電極２０ａ，２０ｂとの間の静電容量を示す。 Hereinafter, acceleration detection in the conventional example will be described. First, detection of acceleration in the x direction will be described. When acceleration in the x direction is applied to the first movable electrode 40, the capacitances C1 and C2 between the first movable electrode 40 and the fixed electrodes 20a and 20b are expressed by the following mathematical formulas, respectively. The The parameter C0 in the equations (1) and (2) is the distance between the first movable electrode 40 and each fixed electrode 20a, 20b in the state where no acceleration in the x direction is applied to the first movable electrode 40. The electrostatic capacity is shown.

Ｃ１＝Ｃ０−ΔＣ …（１）
Ｃ２＝Ｃ０＋ΔＣ …（２）
同様に、第２の可動電極４１にｘ方向の加速度が加えられた場合、第２の可動電極４１と各固定電極２０ｃ，２０ｄとの間の静電容量Ｃ３，Ｃ４は、それぞれ以下に示す数式で表される。尚、数式（３），（４）中のパラメータＣ０は、上記と同様に第２の可動電極４１にｘ方向の加速度が加えられていない状態における第２の可動電極４１と各固定電極２０ｃ，２０ｄとの間の静電容量を示す。 C1 = C0−ΔC (1)
C2 = C0 + ΔC (2)
Similarly, when an acceleration in the x direction is applied to the second movable electrode 41, the capacitances C3 and C4 between the second movable electrode 41 and the fixed electrodes 20c and 20d are expressed by the following equations, respectively. It is represented by Note that the parameter C0 in the equations (3) and (4) is the same as the above, and the second movable electrode 41 and each fixed electrode 20c, when the acceleration in the x direction is not applied to the second movable electrode 41. The capacitance between 20d is shown.

Ｃ３＝Ｃ０−ΔＣ …（３）
Ｃ４＝Ｃ０＋ΔＣ …（４）
而して、各検出電極６ａ〜６ｄを介して上記静電容量Ｃ１〜Ｃ４を検出し、ＡＳＩＣ（Application Specific Integrated Circuit）等を利用して静電容量Ｃ１，Ｃ２の差分値ＣＡ（＝Ｃ１−Ｃ２）、及び静電容量Ｃ３，Ｃ４の差分値ＣＢ（＝Ｃ３−Ｃ４）を算出し、算出された差分値ＣＡ，ＣＢの和（±４ΔＣ）をＸ出力として出力することにより、静電容量の変化から第１の可動電極４０及び第２の可動電極４１に加えられたｘ方向の加速度を検出することができる。 C3 = C0−ΔC (3)
C4 = C0 + ΔC (4)
Thus, the capacitances C1 to C4 are detected via the detection electrodes 6a to 6d, and the difference value CA (= C1−) of the capacitances C1 and C2 is detected using an ASIC (Application Specific Integrated Circuit) or the like. C2) and the difference value CB (= C3−C4) between the capacitances C3 and C4, and the sum of the calculated difference values CA and CB (± 4ΔC) is output as the X output, whereby the capacitance From this change, the acceleration in the x direction applied to the first movable electrode 40 and the second movable electrode 41 can be detected.

次に、ｚ方向における加速度の検出について説明する。第１の可動電極４０にｚ方向の加速度が加えられた場合、第１の可動電極４０と各固定電極２０ａ，２０ｂとの間の静電容量Ｃ１，Ｃ２は、それぞれ以下に示す数式で表される。尚、数式（５），（６）中のパラメータＣ０は、第１の可動電極４０にｚ方向の加速度が加えられていない状態における第１の可動電極４０と各固定電極２０ａ，２０ｂとの間の静電容量を示す。 Next, detection of acceleration in the z direction will be described. When acceleration in the z direction is applied to the first movable electrode 40, the capacitances C1 and C2 between the first movable electrode 40 and the fixed electrodes 20a and 20b are expressed by the following equations, respectively. The The parameter C0 in the equations (5) and (6) is the distance between the first movable electrode 40 and each fixed electrode 20a, 20b in the state where no acceleration in the z direction is applied to the first movable electrode 40. The electrostatic capacity is shown.

Ｃ１＝Ｃ０＋ΔＣ …（５）
Ｃ２＝Ｃ０−ΔＣ …（６）
同様に、第２の可動電極４１にｚ方向の加速度が加えられた場合、第２の可動電極４１と各固定電極２０ｃ，２０ｄとの間の静電容量Ｃ３，Ｃ４は、それぞれ以下に示す数式で表される。尚、数式（７），（８）中のパラメータＣ０は、上記と同様に第２の可動電極４１にｚ方向の加速度が加えられていない状態における第２の可動電極４１と各固定電極２０ｃ，２０ｄとの間の静電容量を示す。 C1 = C0 + ΔC (5)
C2 = C0−ΔC (6)
Similarly, when an acceleration in the z direction is applied to the second movable electrode 41, the capacitances C3 and C4 between the second movable electrode 41 and the fixed electrodes 20c and 20d are expressed by the following equations, respectively. It is represented by It should be noted that the parameter C0 in the equations (7) and (8) is the same as described above, and the second movable electrode 41 and each fixed electrode 20c, in the state where no acceleration in the z direction is applied to the second movable electrode 41. The capacitance between 20d is shown.

Ｃ３＝Ｃ０−ΔＣ …（７）
Ｃ４＝Ｃ０＋ΔＣ …（８）
而して、各検出電極６ａ〜６ｄを介して上記静電容量Ｃ１〜Ｃ４を検出し、ＡＳＩＣ等を利用して静電容量Ｃ１，Ｃ２の差分値ＣＡ（＝Ｃ１−Ｃ２）、及び静電容量Ｃ３，Ｃ４の差分値ＣＢ（＝Ｃ３−Ｃ４）を算出し、算出された差分値ＣＡ，ＣＢの和（±４ΔＣ）をＺ出力として出力することにより、静電容量の変化から第１の可動電極４０及び第２の可動電極４１に加えられたｚ方向の加速度を検出することができる。 C3 = C0−ΔC (7)
C4 = C0 + ΔC (8)
Thus, the capacitances C1 to C4 are detected via the detection electrodes 6a to 6d, and the difference value CA (= C1−C2) between the capacitances C1 and C2 using the ASIC or the like, and the electrostatic capacitance. A difference value CB (= C3−C4) between the capacitors C3 and C4 is calculated, and the sum (± 4ΔC) of the calculated difference values CA and CB is output as a Z output. The acceleration in the z direction applied to the movable electrode 40 and the second movable electrode 41 can be detected.

米国特許公開２００７−００００３２３号公報US Patent Publication No. 2007-0000223

ところで、上記従来例では、測定レンジを超える過大な加速度が加えられた場合において、各ビーム部５ａ〜５ｄを軸とした回転方向に対しては、突起部４０ｂや付着防止膜２３ａ，２３ｂによって上部固定板２ａ及び下部固定板２ｂとセンサチップ１とが直接衝突するのを防ぐことでセンサチップ１の破損を防止している。しかしながら、ｘｙ平面における各ビーム部５ａ〜５ｄの軸と直交する方向に対しては何の手段も講じられていない。
このため、測定レンジを超える過大な加速度が加えられた場合において、各可動電極４０，４１が前記方向において過度に揺動することで各ビーム部５ａ〜５ｄに生じる曲げ応力によって各ビーム部５ａ〜５ｄが破損する虞があった。 By the way, in the above-described conventional example, when excessive acceleration exceeding the measurement range is applied, the protrusion 40b and the adhesion preventing films 23a and 23b are used for the rotation direction around the beam portions 5a to 5d. The sensor chip 1 is prevented from being damaged by preventing the fixing plate 2a and the lower fixing plate 2b and the sensor chip 1 from directly colliding with each other. However, no means is taken with respect to the direction orthogonal to the axes of the beam portions 5a to 5d in the xy plane.
For this reason, when an excessive acceleration exceeding the measurement range is applied, each of the beam portions 5a to 5d is caused by bending stress generated in each of the beam portions 5a to 5d due to excessive swinging of the movable electrodes 40 and 41 in the direction. There was a possibility that 5d might be damaged.

本発明は、上記の点に鑑みて為されたもので、測定レンジを超える過大な加速度が加えられた場合におけるビーム部の破損を防止することのできる加速度センサを提供することを目的とする。 The present invention has been made in view of the above points, and an object of the present invention is to provide an acceleration sensor capable of preventing the beam portion from being damaged when an excessive acceleration exceeding the measurement range is applied.

請求項１の発明は、上記目的を達成するために、可動電極と、可動電極を所定の間隔を空けて囲む枠部と、可動電極と枠部とを連結するとともに可動電極を枠部に対して揺動自在に支持する１対のビーム部と、可動電極の表面における１対のビーム部を結ぶ直線を境界線とした一方側および他方側に対してそれぞれ所定の間隔を空けて対向配置される１対の固定電極とを備え、ビーム部を軸とした可動電極の揺動に伴う可動電極と固定電極との間の静電容量の変化から加速度を検出する加速度センサであって、可動電極の表面と平行する平面において可動電極が少なくともビーム部の軸方向と直交する方向へ移動するのを制限するストッパ手段を設けたことを特徴とする。 In order to achieve the above object, the invention of claim 1 connects the movable electrode, the frame portion surrounding the movable electrode with a predetermined interval, the movable electrode and the frame portion, and the movable electrode to the frame portion. And a pair of beam portions that are supported so as to be swingable and a straight line connecting the pair of beam portions on the surface of the movable electrode as a boundary line, and are arranged to face each other with a predetermined interval therebetween. An acceleration sensor that detects acceleration from a change in electrostatic capacitance between the movable electrode and the fixed electrode that accompanies the swinging of the movable electrode with the beam portion as an axis. Stopper means is provided for restricting movement of the movable electrode in a direction orthogonal to the axial direction of the beam portion on a plane parallel to the surface of the beam.

請求項２の発明は、請求項１の発明において、ストッパ手段は、可動電極の外周縁に設けられて枠部と対向する一面が開口するとともにビーム部の軸方向において対向する内壁、及びビーム部の軸方向と直交する方向において枠部と対向する内壁を有する凹所と、枠部に設けられてその一部が凹所の内側に進入するとともに加速度が加えられていない状態で凹所の各内壁との間に所定の隙間を有する突片とから成ることを特徴とする。 According to a second aspect of the present invention, in the first aspect of the present invention, the stopper means is provided on the outer peripheral edge of the movable electrode, and has an inner wall facing the axial direction of the beam portion that is open at one surface facing the frame portion, and the beam portion. A recess having an inner wall facing the frame portion in a direction orthogonal to the axial direction of each of the recesses, and each of the recesses provided in the frame portion with a part thereof entering the inside of the recess and no acceleration being applied. It comprises a projecting piece having a predetermined gap between the inner wall and the inner wall.

請求項３の発明は、請求項１の発明において、ストッパ手段は、可動電極の外周縁において少なくともビーム部の軸方向と直交する方向の各々に設けられて枠部と可動電極との間の距離を他の部位よりも狭める突部から成ることを特徴とする。 According to a third aspect of the present invention, in the first aspect of the present invention, the stopper means is provided at each of the outer peripheral edges of the movable electrode at least in the direction orthogonal to the axial direction of the beam portion, and the distance between the frame portion and the movable electrode. It is characterized by comprising a projecting portion that narrows the surface from other portions.

請求項４の発明は、請求項３の発明において、可動電極及び枠部は平面視略矩形状であって、ビーム部は、その軸部が可動電極及び枠部の対角線上に位置するように形成され、突部は、可動電極において前記対角線とは異なる対角線上に位置するように形成されたことを特徴とする。 According to a fourth aspect of the present invention, in the third aspect of the invention, the movable electrode and the frame portion are substantially rectangular in a plan view, and the beam portion is positioned so that the shaft portion is located on a diagonal line of the movable electrode and the frame portion. The projecting portion is formed so as to be positioned on a diagonal line different from the diagonal line in the movable electrode.

請求項１の発明によれば、測定レンジを超える過大な加速度が加えられた場合において、可動電極の表面と平行する平面上であってビーム部の軸方向と直交する方向へ可動電極が移動するのをストッパ手段によって制限することができる。したがって、可動電極の過度の揺動によってビーム部に曲げ応力が発生するのを防ぐことができ、ビーム部の破損を防止することができる。 According to the first aspect of the present invention, when an excessive acceleration exceeding the measurement range is applied, the movable electrode moves on a plane parallel to the surface of the movable electrode and in a direction perpendicular to the axial direction of the beam portion. Can be limited by the stopper means. Therefore, it is possible to prevent bending stress from being generated in the beam portion due to excessive swinging of the movable electrode, and it is possible to prevent damage to the beam portion.

請求項２の発明によれば、測定レンジを超える過大な加速度が加えられた場合において、枠部の突片が可動電極の凹所の内壁に当接することで、可動電極の表面と平行する平面上であってビーム部の軸方向、及び軸方向と直交する方向での可動電極の移動を制限することができる。したがって、可動電極の過度の揺動によってビーム部に曲げ応力が発生するのを防ぐことができ、ビーム部の破損を防止することができる。 According to the invention of claim 2, when an excessive acceleration exceeding the measurement range is applied, the projecting piece of the frame portion abuts against the inner wall of the recess of the movable electrode, so that the plane parallel to the surface of the movable electrode It is possible to limit the movement of the movable electrode in the axial direction of the beam portion and in the direction orthogonal to the axial direction. Therefore, it is possible to prevent bending stress from being generated in the beam portion due to excessive swinging of the movable electrode, and it is possible to prevent damage to the beam portion.

請求項３の発明によれば、測定レンジを超える過大な加速度が加えられた場合において、可動電極の突部が枠部に当接することで可動電極の表面と平行する平面上であってビーム部の軸方向と直交する方向への可動電極の移動を制限することができる。したがって、可動電極の過度の揺動によってビーム部に曲げ応力が発生するのを防ぐことができ、ビーム部の破損を防止することができる。 According to the invention of claim 3, when an excessive acceleration exceeding the measurement range is applied, the projecting portion of the movable electrode is in contact with the frame portion so that the beam portion is on a plane parallel to the surface of the movable electrode. The movement of the movable electrode in a direction orthogonal to the axial direction of the first electrode can be restricted. Therefore, it is possible to prevent bending stress from being generated in the beam portion due to excessive swinging of the movable electrode, and it is possible to prevent damage to the beam portion.

請求項４の発明によれば、測定レンジを超える過大な加速度が加えられた場合において、可動電極の突部が枠部に当接することで可動電極の表面と平行する平面上であってビーム部の軸方向、及び軸方向と直交する方向への可動電極の移動を制限することができる。したがって、可動電極の過度の揺動によってビーム部に曲げ応力が発生するのを防ぐことができ、ビーム部の破損を防止することができる。 According to the invention of claim 4, when an excessive acceleration exceeding the measurement range is applied, the projecting portion of the movable electrode is in contact with the frame portion so that the beam portion is on a plane parallel to the surface of the movable electrode. The movement of the movable electrode in the axial direction and the direction orthogonal to the axial direction can be restricted. Therefore, it is possible to prevent bending stress from being generated in the beam portion due to excessive swinging of the movable electrode, and it is possible to prevent damage to the beam portion.

本発明に係る加速度センサの実施形態１を示す図で、（ａ）は平面図で、（ｂ）は固定電極との位置関係を示す平面図である。BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Embodiment 1 of the acceleration sensor which concerns on this invention, (a) is a top view, (b) is a top view which shows the positional relationship with a fixed electrode. （ａ）は同上の断面図で、（ｂ）は同上の突片の厚みを変更した場合における断面図である。(A) is sectional drawing same as the above, (b) is sectional drawing at the time of changing the thickness of a protruding piece same as the above. 本発明に係る加速度センサの実施形態２を示す図で、（ａ）は平面図で、（ｂ）は固定電極との位置関係を示す平面図である。It is a figure which shows Embodiment 2 of the acceleration sensor which concerns on this invention, (a) is a top view, (b) is a top view which shows the positional relationship with a fixed electrode. （ａ）は同上の断面図で、（ｂ）は同上の突部の厚みを変更した場合における断面図である。(A) is sectional drawing same as the above, (b) is sectional drawing at the time of changing the thickness of the protrusion part same as the above. 従来の加速度センサを示す分解斜視図である。It is a disassembled perspective view which shows the conventional acceleration sensor. 同上のｙｚ平面における断面図である。It is sectional drawing in yz plane same as the above.

（実施形態１）
以下、本発明に係る加速度センサの実施形態１について図面を用いて説明する。但し、本実施形態の基本的な構成は従来例と共通であるので、共通する部位には同一の番号を付して説明を省略する。また、以下の説明では、従来例での説明と同様に、図５における上下を上下方向、センサチップ１の短手方向と平行な方向をｘ方向、センサチップ１の長手方向と平行な方向をｙ方向と定めるものとする。 (Embodiment 1)
Hereinafter, a first embodiment of an acceleration sensor according to the present invention will be described with reference to the drawings. However, since the basic configuration of this embodiment is the same as that of the conventional example, common portions are denoted by the same reference numerals and description thereof is omitted. In the following description, as in the conventional example, the vertical direction in FIG. 5 is the vertical direction, the direction parallel to the short direction of the sensor chip 1 is the x direction, and the direction parallel to the longitudinal direction of the sensor chip 1 is It shall be defined as the y direction.

本実施形態は、図１（ａ），（ｂ）に示すように、平面視略正方形状の第１の可動電極４０と、第１の可動電極４０を所定の間隔を空けて囲む平面視略正方形状の第１の枠部３０と、第１の可動電極４０と第１の枠部３０とを連結するとともに第１の可動電極４０を第１の枠部３０に対して揺動自在に支持する１対の第１のビーム部５ａ，５ｂと、第１の可動電極４０の上面（表面）における１対の第１のビーム部５ａ，５ｂを結ぶ直線を境界線とした一方側および他方側に対してそれぞれ所定の間隔を空けて対向配置される第１の固定電極２０ａ及び第２の固定電極２０ｂとを備え、第１の可動電極４０の下面（裏面）における１対の第１のビーム部５ａ，５ｂを結ぶ直線を境界線とした一方の側に凹部４０ａが設けられている。 In this embodiment, as shown in FIGS. 1A and 1B, the first movable electrode 40 having a substantially square shape in plan view and the plan view schematically surrounding the first movable electrode 40 with a predetermined interval therebetween. The first frame 30 having a square shape, the first movable electrode 40 and the first frame 30 are connected to each other, and the first movable electrode 40 is swingably supported with respect to the first frame 30. One side and the other side with a straight line connecting the pair of first beam portions 5a and 5b and the pair of first beam portions 5a and 5b on the upper surface (surface) of the first movable electrode 40 as a boundary line A pair of first beams on the lower surface (back surface) of the first movable electrode 40. The first fixed electrode 20a and the second fixed electrode 20b are arranged to face each other with a predetermined distance therebetween. A concave portion 40a is provided on one side having a straight line connecting the portions 5a and 5b as a boundary line.

第１のビーム部５ａ，５ｂは、図１（ａ）に示すように、その軸部が第１の枠部３０の対角線上に位置するように形成されている。そして、第１の枠部３０の前記対角線と直交する対角線上には、第１の可動電極４０に向かって突出する平面視略矩形状の１対の突片３０ａが第１の枠部３０と一体に形成されている。また、第１の可動電極４０の各突片３０ａと対向する部位には、第１の枠部３０と対向する一面が開口した凹所４０ｃがそれぞれ厚み方向（上下方向）に貫設されている。これら突片３０ａと凹所４０ｃとで、第１の可動電極４０の表面と平行する平面（ｘｙ平面）において第１の可動電極４０が少なくとも第１のビーム部５ａ，５ｂの軸方向と直交する方向へ移動するのを制限するストッパ手段を構成している。 As shown in FIG. 1A, the first beam portions 5 a and 5 b are formed so that their shaft portions are positioned on the diagonal line of the first frame portion 30. A pair of projecting pieces 30 a having a substantially rectangular shape in plan view and projecting toward the first movable electrode 40 is formed on the diagonal line orthogonal to the diagonal line of the first frame part 30. It is integrally formed. In addition, in a portion of the first movable electrode 40 that faces each projecting piece 30a, a recess 40c that opens on one surface facing the first frame portion 30 is provided in the thickness direction (vertical direction). . With the protruding pieces 30a and the recesses 40c, the first movable electrode 40 is at least orthogonal to the axial direction of the first beam portions 5a and 5b in a plane (xy plane) parallel to the surface of the first movable electrode 40. Stopper means for restricting movement in the direction is configured.

凹所４０ｃは、第１のビーム部５ａ，５ｂの軸方向において対向する内壁と、前記軸方向と直交する方向において第１の枠部３０と対向する内壁とを有する。各突片３０ａは、その端部が各凹所４０ｃの内側に進入し、且つ加速度が加えられていない状態で凹所４０ｃの各内壁との間に所定の隙間を有するように配設されている。このように突片３０ａの端部と凹所４０ｃの各内壁との間に所定の隙間を設けることで、第１の可動電極４０が第１のビーム部５ａ，５ｂを軸として回動する際に、測定レンジの範囲内において突片３０ａと凹所４０ｃとが当接してその回動を阻害するのを防ぐことができる。 The recess 40c has an inner wall that faces the first beam portions 5a and 5b in the axial direction, and an inner wall that faces the first frame portion 30 in a direction orthogonal to the axial direction. Each projecting piece 30a is disposed so that the end thereof enters the inside of each recess 40c and has a predetermined gap between each inner wall of the recess 40c in a state where acceleration is not applied. Yes. As described above, when the predetermined gap is provided between the end of the projecting piece 30a and each inner wall of the recess 40c, the first movable electrode 40 is rotated about the first beam portions 5a and 5b. In addition, it is possible to prevent the protrusion 30a and the recess 40c from coming into contact with each other within the measurement range and hindering the rotation thereof.

而して、測定レンジを超える過大な加速度が加えられた場合において、第１の枠部３０の各突片３０ａが第１の可動電極４０の各凹所４０ｃの内壁に当接することで、ｘｙ平面における第１のビーム部５ａ，５ｂの軸方向、及び軸方向と直交する方向での第１の可動電極４０の移動を制限することができる。したがって、第１の可動電極４０の過度の揺動によって第１のビーム部５ａ，５ｂに曲げ応力が発生するのを防ぐことができ、第１のビーム部５ａ，５ｂの破損を防止することができる。 Thus, when an excessive acceleration exceeding the measurement range is applied, each projecting piece 30a of the first frame portion 30 comes into contact with the inner wall of each recess 40c of the first movable electrode 40, so that xy The movement of the first movable electrode 40 in the axial direction of the first beam portions 5a and 5b in the plane and the direction orthogonal to the axial direction can be restricted. Therefore, it is possible to prevent bending stress from being generated in the first beam portions 5a and 5b due to excessive swinging of the first movable electrode 40, and it is possible to prevent damage to the first beam portions 5a and 5b. it can.

ところで、第１の枠部３０の角部と第１の可動電極４０の角部との間の距離が長い場合、突片３０ａの長さも長くなるために突片３０ａの強度が低下してしまう。また、第１の可動電極４０に凹所４０ｃを貫設すると、第１の可動電極４０の質量が小さくなり、加速度の検出感度が低下してしまう。このため、本実施形態では第１の可動電極４０を大きく形成することでこれらの問題を解決している。しかしながら、第１の可動電極４０を大きくすると、第１の枠部３０と第１の可動電極４０との間の距離が短くなるために第１のビーム部５ａ，５ｂの軸方向の長さが短くなってしまい、加速度の検出感度が低下してしまう。 By the way, when the distance between the corner portion of the first frame portion 30 and the corner portion of the first movable electrode 40 is long, the length of the protrusion piece 30a is also increased, so that the strength of the protrusion piece 30a is reduced. . Further, if the recess 40c is provided through the first movable electrode 40, the mass of the first movable electrode 40 is reduced, and the acceleration detection sensitivity is lowered. For this reason, in this embodiment, these problems are solved by forming the first movable electrode 40 large. However, when the first movable electrode 40 is enlarged, the distance between the first frame portion 30 and the first movable electrode 40 is shortened, so that the axial lengths of the first beam portions 5a and 5b are reduced. This shortens the acceleration detection sensitivity.

そこで、本実施形態では、第１の可動電極４０の第１のビーム部５ａ，５ｂが設けられている角部において、それぞれ第１のビーム部５ａ，５ｄの幅方向における両側縁に切り欠き４０ｄを貫設し、第１の枠部３０の角部と、第１の可動電極４０の角部よりも内側の部位とを連結するように第１のビーム部５ａ，５ｂを形成している。このため、第１の枠部３０の角部と第１の可動電極４０の角部とを連結する場合と比較して軸方向の長さが長くなるので、第１の可動電極４０が大きくなっても第１のビーム部５ａ，５ｂが必要な軸方向の長さを確保することができる。 Therefore, in the present embodiment, at the corner portions of the first movable electrode 40 where the first beam portions 5a and 5b are provided, notches 40d are formed on both side edges in the width direction of the first beam portions 5a and 5d, respectively. The first beam portions 5a and 5b are formed so as to connect the corner portion of the first frame portion 30 and the portion inside the corner portion of the first movable electrode 40. For this reason, since the axial length becomes longer compared with the case where the corners of the first frame 30 and the corners of the first movable electrode 40 are connected, the first movable electrode 40 becomes larger. Even in this case, the first beam portions 5a and 5b can ensure the necessary axial length.

また、本実施形態では、センサチップ１が支持基板Ｃと活性層Ａにより酸化膜Ｂを挟持したＳＯＩ基板から成る。このため、図２（ａ）に示すように、突片３０ａを活性層Ａで形成すれば第１のビーム部５ａ，５ｂと同時に形成することが可能であり、製造が容易となる。また、図２（ｂ）に示すように、突片３０ａを活性層Ａのみならず酸化膜Ｂ及び支持基板Ｃも含めて形成すれば、突片３０ａの強度を高めることができる。 In this embodiment, the sensor chip 1 is composed of an SOI substrate in which the oxide film B is sandwiched between the support substrate C and the active layer A. Therefore, as shown in FIG. 2A, if the projecting piece 30a is formed of the active layer A, it can be formed at the same time as the first beam portions 5a and 5b, and the manufacture becomes easy. Further, as shown in FIG. 2B, if the protrusion 30a is formed including not only the active layer A but also the oxide film B and the support substrate C, the strength of the protrusion 30a can be increased.

尚、従来例のように第１の可動電極４０の対向する２辺の略中央部と第１の枠部３０の側壁部とを連結するように第１のビーム部５ａ，５ｂを形成した場合でも、第１のビーム部５ａ，５ｂの軸方向と直交する方向において第１の枠部３０及び第１の可動電極４０にそれぞれ突片３０ａ及び凹所４０ｃを設けることで、本実施形態と同様の効果を奏することができる。また、本実施形態では、第１の枠部３０、第１の可動電極４０、第１のビーム部５ａ，５ｂに関する構成についてのみ記載しているが、従来例における第２の枠部３１、第２の可動電極４１、第２のビーム部５ｃ，５ｄに関する構成に対して本実施形態の構成を採用しても構わないことは言うまでもない。 When the first beam portions 5a and 5b are formed so as to connect the substantially central portions of the two opposing sides of the first movable electrode 40 and the side wall portions of the first frame portion 30 as in the conventional example. However, by providing the projecting pieces 30a and the recesses 40c in the first frame 30 and the first movable electrode 40 in the direction orthogonal to the axial direction of the first beam portions 5a and 5b, respectively, as in the present embodiment. The effect of can be produced. Moreover, in this embodiment, although only the structure regarding the 1st frame part 30, the 1st movable electrode 40, and the 1st beam parts 5a and 5b is described, the 2nd frame part 31 in the prior art example, the 1st It goes without saying that the configuration of the present embodiment may be adopted for the configuration relating to the second movable electrode 41 and the second beam portions 5c and 5d.

（実施形態２）
以下、本発明に係る加速度センサの実施形態２について図面を用いて説明する。但し、本実施形態の基本的な構成は実施形態１と共通であるので、共通する部位には同一の番号を付して説明を省略する。また、以下の説明では、従来例での説明と同様に、図５における上下を上下方向、センサチップ１の短手方向と平行な方向をｘ方向、センサチップ１の長手方向と平行な方向をｙ方向と定めるものとする。本実施形態は、図３（ａ），（ｂ）に示すように、実施形態１の突片３０ａ及び凹所４０ｃを設ける代わりに、突部４０ｅをストッパ手段として設けている。 (Embodiment 2)
Hereinafter, an acceleration sensor according to a second embodiment of the present invention will be described with reference to the drawings. However, since the basic configuration of the present embodiment is common to that of the first embodiment, common portions are denoted by the same reference numerals and description thereof is omitted. In the following description, as in the conventional example, the vertical direction in FIG. 5 is the vertical direction, the direction parallel to the short direction of the sensor chip 1 is the x direction, and the direction parallel to the longitudinal direction of the sensor chip 1 is It shall be defined as the y direction. In this embodiment, as shown in FIGS. 3A and 3B, instead of providing the projecting piece 30a and the recess 40c of the first embodiment, a projecting portion 40e is provided as a stopper means.

突部４０ｅは、図３（ａ）に示すように、第１の可動電極４０の第１のビーム部５ａ，５ｂの軸方向と直交する対角線上において、対向する第１の枠部３０の角部との間の距離が他の部位における第１の枠部３０と第１の可動電極４０との間の距離よりも狭くなるように平面視略矩形状に形成されている。また、第１の枠部３０の突部４０ｅと対向する角部には、突部４０ｅの衝突による応力を緩和するために突部４０ｅの端面と平行な面を有する平坦部３０ｂが形成されている。 As shown in FIG. 3A, the protrusion 40e is formed on the diagonal line of the first movable electrode 40 on the diagonal line orthogonal to the axial direction of the first beam portions 5a and 5b. It is formed in a substantially rectangular shape in plan view so that the distance between the first and second parts is narrower than the distance between the first frame part 30 and the first movable electrode 40 in other parts. Further, a flat portion 30b having a surface parallel to the end face of the protrusion 40e is formed at the corner portion of the first frame portion 30 facing the protrusion 40e in order to relieve stress due to the collision of the protrusion 40e. Yes.

而して、測定レンジを超える過大な加速度が加えられた場合において、第１の可動電極４０の突部４０ｅが第１の枠部３０の平坦部３０ｂに当接することで、ｘｙ平面における第１のビーム部５ａ，５ｂの軸方向、及び軸方向と直交する方向での第１の可動電極４０の移動を制限することができる。したがって、第１の可動電極４０の過度の揺動によって第１のビーム部５ａ，５ｂに曲げ応力が発生するのを防ぐことができ、第１のビーム部５ａ，５ｂの破損を防止することができる。 Thus, when an excessive acceleration exceeding the measurement range is applied, the protrusion 40e of the first movable electrode 40 comes into contact with the flat portion 30b of the first frame portion 30, so that the first in the xy plane is obtained. The movement of the first movable electrode 40 in the axial direction of the beam portions 5a and 5b and the direction orthogonal to the axial direction can be restricted. Therefore, it is possible to prevent bending stress from being generated in the first beam portions 5a and 5b due to excessive swinging of the first movable electrode 40, and it is possible to prevent damage to the first beam portions 5a and 5b. it can.

ところで、本実施形態では、センサチップ１が支持基板Ｃと活性層Ａにより酸化膜Ｂを挟持したＳＯＩ基板から成る。このため、図４（ａ）に示すように、突部４０ｅを活性層Ａで形成すれば第１のビーム部５ａ，５ｂと同時に形成することが可能であり、製造が容易となる。また、図４（ｂ）に示すように、突部４０ｅを活性層Ａのみならず酸化膜Ｂ及び支持基板Ｃも含めて形成すれば、突部４０ｅの強度を高めることができる。 By the way, in this embodiment, the sensor chip 1 is composed of an SOI substrate in which the oxide film B is sandwiched between the support substrate C and the active layer A. For this reason, as shown in FIG. 4A, if the protrusion 40e is formed of the active layer A, it can be formed simultaneously with the first beam portions 5a and 5b, and the manufacture becomes easy. Further, as shown in FIG. 4B, if the protrusion 40e is formed including not only the active layer A but also the oxide film B and the support substrate C, the strength of the protrusion 40e can be increased.

尚、従来例のように第１の可動電極４０の対向する２辺の略中央部と第１の枠部３０の側壁部とを連結するように第１のビーム部５ａ，５ｂを形成した場合でも、第１のビーム部５ａ，５ｂの軸方向と直交する方向において第１の可動電極４０に突部４０ｅを設けることで、ｘｙ平面における第１のビーム部５ａ，５ｂの軸方向と直交する方向での第１の可動電極４０の移動を制限することができる。また、本実施形態では、第１の枠部３０、第１の可動電極４０、第１のビーム部５ａ，５ｂに関する構成についてのみ記載しているが、従来例における第２の枠部３１、第２の可動電極４１、第２のビーム部５ｃ，５ｄに関する構成に対して本実施形態の構成を採用しても構わないことは言うまでもない。 When the first beam portions 5a and 5b are formed so as to connect the substantially central portions of the two opposing sides of the first movable electrode 40 and the side wall portions of the first frame portion 30 as in the conventional example. However, by providing the protrusion 40e on the first movable electrode 40 in a direction orthogonal to the axial direction of the first beam portions 5a and 5b, the axial direction of the first beam portions 5a and 5b in the xy plane is orthogonal. The movement of the first movable electrode 40 in the direction can be restricted. Moreover, in this embodiment, although only the structure regarding the 1st frame part 30, the 1st movable electrode 40, and the 1st beam parts 5a and 5b is described, the 2nd frame part 31 in the prior art example, the 1st It goes without saying that the configuration of the present embodiment may be adopted for the configuration relating to the second movable electrode 41 and the second beam portions 5c and 5d.

２０ａ第１の固定電極
２０ｂ第２の固定電極
３０第１の枠部
３０ａ突片
４０第１の可動電極
４０ｃ凹所
５ａ，５ｂ第１のビーム部 20a 1st fixed electrode 20b 2nd fixed electrode 30 1st frame part 30a Projection piece 40 1st movable electrode 40c Recess 5a, 5b 1st beam part

Claims

可動電極と、可動電極を所定の間隔を空けて囲む枠部と、可動電極と枠部とを連結するとともに可動電極を枠部に対して揺動自在に支持する１対のビーム部と、可動電極の表面における１対のビーム部を結ぶ直線を境界線とした一方側および他方側に対してそれぞれ所定の間隔を空けて対向配置される１対の固定電極とを備え、ビーム部を軸とした可動電極の揺動に伴う可動電極と固定電極との間の静電容量の変化から加速度を検出する加速度センサであって、可動電極の表面と平行する平面において可動電極が少なくともビーム部の軸方向と直交する方向へ移動するのを制限するストッパ手段を設けたことを特徴とする加速度センサ。 A movable electrode; a frame portion surrounding the movable electrode with a predetermined interval; a pair of beam portions that connect the movable electrode and the frame portion and support the movable electrode with respect to the frame portion; A pair of fixed electrodes disposed opposite to each other at a predetermined interval with respect to one side and the other side of which a straight line connecting a pair of beam portions on the surface of the electrode is a boundary line. An acceleration sensor that detects acceleration from a change in capacitance between the movable electrode and the fixed electrode accompanying the swinging of the movable electrode, wherein the movable electrode is at least an axis of the beam portion in a plane parallel to the surface of the movable electrode. An acceleration sensor provided with stopper means for restricting movement in a direction orthogonal to the direction.

前記ストッパ手段は、可動電極の外周縁に設けられて枠部と対向する一面が開口するとともにビーム部の軸方向において対向する内壁、及びビーム部の軸方向と直交する方向において枠部と対向する内壁を有する凹所と、枠部に設けられてその一部が凹所の内側に進入するとともに加速度が加えられていない状態で凹所の各内壁との間に所定の隙間を有する突片とから成ることを特徴とする請求項１記載の加速度センサ。 The stopper means is provided on the outer peripheral edge of the movable electrode and opens on one surface facing the frame portion and faces the frame portion in the direction orthogonal to the axial direction of the beam portion and the inner wall facing the beam portion in the axial direction. A recess having an inner wall, and a projecting piece which is provided in the frame portion and a part thereof enters the inside of the recess and has a predetermined gap between the inner wall of the recess in a state where no acceleration is applied. The acceleration sensor according to claim 1, comprising:

前記ストッパ手段は、可動電極の外周縁において少なくともビーム部の軸方向と直交する方向の各々に設けられて枠部と可動電極との間の距離を他の部位よりも狭める突部から成ることを特徴とする請求項１記載の加速度センサ。 The stopper means is formed of a protrusion provided at each of the outer peripheral edges of the movable electrode at least in a direction orthogonal to the axial direction of the beam portion and narrowing the distance between the frame portion and the movable electrode from other portions. The acceleration sensor according to claim 1.

前記可動電極及び枠部は平面視略矩形状であって、ビーム部は、その軸部が可動電極及び枠部の対角線上に位置するように形成され、突部は、可動電極において前記対角線とは異なる対角線上に位置するように形成されたことを特徴とする請求項３記載の加速度センサ。
The movable electrode and the frame portion have a substantially rectangular shape in plan view, and the beam portion is formed such that the shaft portion thereof is positioned on a diagonal line of the movable electrode and the frame portion, and the protrusion is formed on the diagonal line of the movable electrode. The acceleration sensor according to claim 3, wherein the acceleration sensors are located on different diagonal lines.