JP2012225813A

JP2012225813A - Three axis accelerometer

Info

Publication number: JP2012225813A
Application number: JP2011094610A
Authority: JP
Inventors: Daisuke Nakamura; 大輔中村; Katsuya Morinaka; 克也森仲
Original assignee: Panasonic Corp
Current assignee: Panasonic Corp
Priority date: 2011-04-21
Filing date: 2011-04-21
Publication date: 2012-11-15

Abstract

PROBLEM TO BE SOLVED: To provide a 3-axis accelerometer capable of accurately detecting the acceleration in three axis directions of X-axis, Y-axis and Z-axis without generating any cross-axis sensitivity and ensuring the sensor sensitivity even when an acceleration detection element is reduced in size and height.SOLUTION: The 3-axis accelerometer includes a first weight part 23 formed at the substantially central area of a base plate 21; a support frame portion 24; a plurality of beam-like flexible portions 25, 25' and 26, 26'; and a plurality of strain resistance elements Rx21, Rx22 and the like. Plural pairs of thin portions 27, 27', 28, 28', 29, 29' and 30, 30', each pair of which is parallel to each other and substantially symmetrical with respect to the central axis of each pair of beam-like flexible portions are formed in the support frame portion; each of second, third, fourth and fifth weight parts 31-34 is formed therein.

Description

本発明は自動車や航空機等の輸送機器や携帯端末等に搭載され、互いに直交するＸ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を検出する３軸加速度センサに関する。 The present invention relates to a three-axis acceleration sensor that is mounted on a transport device such as an automobile or an aircraft, a portable terminal, or the like and detects acceleration in three axes including an X axis, a Y axis, and a Z axis that are orthogonal to each other.

図５（ａ）は従来の加速度センサの検出素子の上面図、図５（ｂ）は図５（ａ）の検出素子のＸ軸に平行なＡ−Ａ線での断面図を示す（特許文献１参照）。 5A is a top view of a detection element of a conventional acceleration sensor, and FIG. 5B is a cross-sectional view of the detection element of FIG. 5A taken along line AA parallel to the X axis (Patent Literature). 1).

図５（ａ）（ｂ）において、１はＸＹ平面に平行に配置されたシリコン等からなる基板であり、該基板１の底面側をエッチング処理するとともに貫通孔２を形成することにより、厚肉部からなる錘部３とそれを囲むように配された支持枠部４と、薄肉で該錘部３および支持枠部４とを接続するＸ軸に平行な第１、第２の梁状可撓部５，５′と、薄肉で該錘部３および支持枠部４とを接続するＹ軸に平行な第３、第４の梁状可撓部６，６′と、が形成されている。前記第１の梁状可撓部５と支持枠部４との連結端部には歪抵抗素子Ｒｘ１を、前記第１の梁状可撓部５と錘部３との連結端部には歪抵抗素子Ｒｘ２を形成している。また、前記第２の梁状可撓部５′と錘部との連結端部には歪抵抗素子Ｒｘ３を、前記第２の梁状可撓部５′と支持枠部４との連結端部には歪抵抗素子Ｒｘ４を形成している。そして、前記歪抵抗素子Ｒｘ１，Ｒｘ２，Ｒｘ３，Ｒｘ４を前記第１、第２の梁状可撓部５，５′の中心線上に配置している。同様にして、前記第３の梁状可撓部６と支持枠部４との連結端部には歪抵抗素子Ｒｙ１，Ｒｚ１を、前記第３の梁状可撓部６と錘部３との連結端部には歪抵抗素子Ｒｙ２，Ｒｚ２を形成している。また、前記第３の梁状可撓部６′と錘部３との連結端部には歪抵抗素子Ｒｙ３，Ｒｚ３を、前記第３の梁状可撓部６′と支持枠部４との連結端部には歪抵抗素子Ｒｙ４，Ｒｚ４を形成している。そして、前記歪抵抗素子Ｒｙ１，Ｒｙ２，Ｒｙ３，Ｒｙ４と前記歪抵抗素子Ｒｚ１，Ｒｚ２，Ｒｚ３，Ｒｚ４とを前記第３、第４の梁状可撓部６，６′の中心線の両側にそれぞれ１列に配置している。 5 (a) and 5 (b), reference numeral 1 denotes a substrate made of silicon or the like arranged in parallel to the XY plane, and the bottom surface side of the substrate 1 is etched and the through-hole 2 is formed to increase the thickness. And a support frame portion 4 disposed so as to surround the weight portion 3, and a first and a second beam-like member that are thin and parallel to the X axis that connects the weight portion 3 and the support frame portion 4. The flexible portions 5 and 5 'and the third and fourth beam-like flexible portions 6 and 6' that are thin and parallel to the Y-axis that connect the weight portion 3 and the support frame portion 4 are formed. . A strain resistance element Rx1 is provided at the connection end portion between the first beam-like flexible portion 5 and the support frame portion 4, and a strain end is provided at the connection end portion between the first beam-like flexible portion 5 and the weight portion 3. A resistive element Rx2 is formed. In addition, a strain resistance element Rx3 is provided at a connection end portion between the second beam-like flexible portion 5 'and the weight portion, and a connection end portion between the second beam-like flexible portion 5' and the support frame portion 4. Is formed with a strain resistance element Rx4. The strain resistance elements Rx1, Rx2, Rx3, Rx4 are arranged on the center line of the first and second beam-like flexible portions 5, 5 ′. Similarly, the strain resistance elements Ry1 and Rz1 are connected to the connecting end portion of the third beam-like flexible portion 6 and the support frame portion 4, and the third beam-like flexible portion 6 and the weight portion 3 are connected to each other. Strain resistance elements Ry2 and Rz2 are formed at the connection end. Further, strain resistance elements Ry3 and Rz3 are provided at the connecting end portion between the third beam-like flexible portion 6 'and the weight portion 3, and the third beam-like flexible portion 6' and the support frame portion 4 are connected to each other. Strain resistance elements Ry4 and Rz4 are formed at the connection end. The strain resistance elements Ry1, Ry2, Ry3, Ry4 and the strain resistance elements Rz1, Rz2, Rz3, Rz4 are respectively arranged on both sides of the center line of the third and fourth beam-like flexible portions 6, 6 '. Arranged in one row.

特開２００４−１８４３７３号公報JP 2004-184373 A

しかしながら、上記従来の加速度センサの検出素子においては、１つの軸方向のみに加速度が印加され錘部３にその軸方向の慣性力が働いた場合において、この軸方向の加速度の他に、他の軸方向の加速度も出力される、いわゆる他軸感度のために、加速度の検出精度が低下するという問題点があった。 However, in the detection element of the conventional acceleration sensor, when acceleration is applied only in one axial direction and an inertial force in the axial direction is applied to the weight portion 3, in addition to the acceleration in the axial direction, Due to the so-called other-axis sensitivity in which axial acceleration is also output, there is a problem in that the accuracy of acceleration detection decreases.

以下に、この問題点について説明する。 This problem will be described below.

図６（ａ）は前記第１、第２の梁状可撓部５，５′に形成した歪抵抗素子Ｒｘ１，Ｒｘ２，Ｒｘ３，Ｒｘ４により構成されるブリッジ回路である。図６（ａ）において、歪抵抗素子Ｒｘ１と歪抵抗素子Ｒｘ２との間に電源電圧（Ｖｄｄ）が接続され、歪抵抗素子Ｒｘ３と歪抵抗素子Ｒｘ４との間にアース（Ｖｓｓ）が接続されて、歪抵抗素子Ｒｘ１と歪抵抗素子Ｒｘ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｘ２と歪抵抗素子Ｒｘ３との中点電位（Ｖ２）との差が測定される。Ｘ軸方向の加速度が印加されていない場合には、歪抵抗素子Ｒｘ１，Ｒｘ２，Ｒｘ３，Ｒｘ４は平衡する（Ｒｘ１・Ｒｘ３＝Ｒｘ２・Ｒｘ４）ように構成されており、歪抵抗素子Ｒｘ１と歪抵抗素子Ｒｘ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｘ２と歪抵抗素子Ｒｘ３との中点電位（Ｖ２）との差は零となっている。また、図６（ｂ）は前記第３、第４の梁状可撓部６，６′に形成した歪抵抗素子Ｒｙ１，Ｒｙ２，Ｒｙ３，Ｒｙ４により構成されるブリッジ回路である。図６（ｂ）において、歪抵抗素子Ｒｙ１と歪抵抗素子Ｒｙ２との間に電源電圧（Ｖｄｄ）が接続され、歪抵抗素子Ｒｙ３と歪抵抗素子Ｒｙ４との間にアース（Ｖｓｓ）が接続されて、歪抵抗素子Ｒｙ１と歪抵抗素子Ｒｙ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｙ２と歪抵抗素子Ｒｙ３との中点電位（Ｖ２）との差が測定される。Ｙ軸方向の加速度が印加されていない場合には、歪抵抗素子Ｒｙ１，Ｒｙ２，Ｒｙ３，Ｒｙ４は平衡する（Ｒｙ１・Ｒｙ３＝Ｒｙ２・Ｒｙ４）ように構成されており、歪抵抗素子Ｒｙ１と歪抵抗素子Ｒｙ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｙ２と歪抵抗素子Ｒｙ３との中点電位（Ｖ２）との差は零となっている。さらにまた、図６（ｃ）は前記第３、第４の梁状可撓部６，６′に形成した歪抵抗素子Ｒｚ１，Ｒｚ２，Ｒｚ３，Ｒｚ４により構成されるブリッジ回路である。図６（ｃ）においては、歪抵抗素子Ｒｚ１と歪抵抗素子Ｒｚ２との間に電源電圧（Ｖｄｄ）が接続され、歪抵抗素子Ｒｚ３と歪抵抗素子Ｒｚ４との間にアース（Ｖｓｓ）が接続されているが、歪抵抗素子Ｒｚ１と歪抵抗素子Ｒｚ３との中点電位（Ｖ１）と、歪抵抗素子Ｒｚ２と歪抵抗素子Ｒｚ４との中点電位（Ｖ２）との差が測定される点で図６（ａ）（ｂ）と異なっている。Ｚ軸方向の加速度が印加されていない場合には、歪抵抗素子Ｒｚ１，Ｒｚ２，Ｒｚ３，Ｒｚ４は平衡する（Ｒｚ１・Ｒｚ４＝Ｒｚ２・Ｒｚ３）ように構成されており、歪抵抗素子Ｒｚ１と歪抵抗素子Ｒｚ３との中点電位（Ｖ１）と、歪抵抗素子Ｒｚ２と歪抵抗素子Ｒｚ４との中点電位（Ｖ２）との差は零となっている。 FIG. 6A shows a bridge circuit composed of strain resistance elements Rx1, Rx2, Rx3, Rx4 formed in the first and second beam-like flexible portions 5, 5 ′. In FIG. 6A, the power supply voltage (Vdd) is connected between the strain resistance element Rx1 and the strain resistance element Rx2, and the ground (Vss) is connected between the strain resistance element Rx3 and the strain resistance element Rx4. The difference between the midpoint potential (V1) of the strain resistance element Rx1 and the strain resistance element Rx4 and the midpoint potential (V2) of the strain resistance element Rx2 and the strain resistance element Rx3 is measured. When no acceleration in the X-axis direction is applied, the strain resistance elements Rx1, Rx2, Rx3, and Rx4 are configured to be balanced (Rx1, Rx3 = Rx2, Rx4), and the strain resistance element Rx1 and the strain resistance The difference between the midpoint potential (V1) between the element Rx4 and the midpoint potential (V2) between the strain resistance element Rx2 and the strain resistance element Rx3 is zero. FIG. 6B shows a bridge circuit composed of strain resistance elements Ry1, Ry2, Ry3, and Ry4 formed in the third and fourth beam-like flexible portions 6, 6 ′. In FIG. 6B, the power supply voltage (Vdd) is connected between the strain resistance element Ry1 and the strain resistance element Ry2, and the ground (Vss) is connected between the strain resistance element Ry3 and the strain resistance element Ry4. The difference between the midpoint potential (V1) of the strain resistance element Ry1 and the strain resistance element Ry4 and the midpoint potential (V2) of the strain resistance element Ry2 and the strain resistance element Ry3 are measured. When acceleration in the Y-axis direction is not applied, the strain resistance elements Ry1, Ry2, Ry3, and Ry4 are configured to be balanced (Ry1 · Ry3 = Ry2 · Ry4). The difference between the midpoint potential (V1) of the element Ry4 and the midpoint potential (V2) of the strain resistance element Ry2 and the strain resistance element Ry3 is zero. FIG. 6C shows a bridge circuit constituted by the strain resistance elements Rz1, Rz2, Rz3, Rz4 formed in the third and fourth beam-like flexible portions 6, 6 ′. In FIG. 6C, the power supply voltage (Vdd) is connected between the strain resistance element Rz1 and the strain resistance element Rz2, and the ground (Vss) is connected between the strain resistance element Rz3 and the strain resistance element Rz4. However, the difference between the midpoint potential (V1) of the strain resistance elements Rz1 and Rz3 and the midpoint potential (V2) of the strain resistance elements Rz2 and Rz4 is measured. 6 (a) and (b) are different. When no acceleration in the Z-axis direction is applied, the strain resistance elements Rz1, Rz2, Rz3, and Rz4 are configured to be balanced (Rz1 · Rz4 = Rz2 · Rz3), and the strain resistance element Rz1 and the strain resistance The difference between the midpoint potential (V1) with the element Rz3 and the midpoint potential (V2) between the strain resistance element Rz2 and the strain resistance element Rz4 is zero.

図７（ａ）は従来の加速度センサの検出素子にＸ軸方向の加速度が印加された時の上面図、図７（ｂ）は図７（ａ）のＸ軸に平行なＡ−Ａ線での断面図である。図７（ｂ）において、錘部３はＸ軸方向に向く慣性力Ｆｘにより回動し、歪抵抗素子Ｒｘ１，Ｒｘ３には引張歪が作用して抵抗値が上昇し、歪抵抗素子Ｒｘ２，Ｒｘ４には圧縮歪が作用して抵抗値が低下する。これにより、図６（ａ）のブリッジ回路の平衡が破れ、歪抵抗素子Ｒｘ１と歪抵抗素子Ｒｘ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｘ２と歪抵抗素子Ｒｘ３との中点電位（Ｖ２）との電圧差が検出される。 FIG. 7A is a top view when acceleration in the X-axis direction is applied to the detection element of the conventional acceleration sensor, and FIG. 7B is an AA line parallel to the X-axis in FIG. FIG. In FIG. 7B, the weight portion 3 is rotated by an inertial force Fx directed in the X-axis direction, tensile strain acts on the strain resistance elements Rx1 and Rx3, and the resistance value increases, and the strain resistance elements Rx2 and Rx4. , Compressive strain acts and the resistance value decreases. As a result, the balance of the bridge circuit of FIG. 6A is broken, and the midpoint potential (V1) between the strain resistance element Rx1 and the strain resistance element Rx4 and the midpoint potential between the strain resistance element Rx2 and the strain resistance element Rx3 ( A voltage difference from V2) is detected.

図７（ｃ）は図７（ａ）の第４の梁状可撓部６′と錘部３との連結部近傍におけるＸ軸に平行なＢ−Ｂ線断面図、図７（ｄ）は第４の梁状可撓部６′と支持枠部４との中央部近傍におけるＸ軸に平行なＣ−Ｃ線断面図、図７（ｅ）は第４の梁状可撓部６′と支持枠部４との連結部近傍におけるＸ軸に平行なＤ−Ｄ線断面図である。 FIG. 7C is a cross-sectional view taken along the line BB parallel to the X axis in the vicinity of the connecting portion between the fourth beam-like flexible portion 6 ′ and the weight portion 3 in FIG. 7A, and FIG. FIG. 7E is a cross-sectional view of the fourth beam-like flexible portion 6 ′ and the support frame portion 4 near the center, taken along the line C-C, and FIG. FIG. 6 is a cross-sectional view taken along line D-D parallel to the X axis in the vicinity of the connecting portion with the support frame portion 4.

Ｘ軸の正方向への錘部３の回動に伴い、図７（ｃ）（ｄ）（ｅ）に示すように、前記第４の梁状可撓部６′の断面は支持枠部４との連結部から錘部３との連結部までＺ軸周りに連続的に回転する、すなわち前記第４の梁状可撓部６′が捻られるためＲｚ３には引張歪が作用して抵抗値が上昇する。同様に、前記第３の梁状可撓部６も捻られるためＲｚ２には引張歪が作用して抵抗値が上昇する。これにより、図６（ｃ）のブリッジ回路の平衡が破れ、歪抵抗素子Ｒｚ１と歪抵抗素子Ｒｚ３との中点電位（Ｖ１）と、歪抵抗素子Ｒｚ２と歪抵抗素子Ｒｚ４との中点電位（Ｖ２）との電圧差が発生するため、あたかもＺ軸方向に加速度が印加されたかのような偽信号、すなわち他軸感度が発生することになる。なお、歪抵抗素子Ｒｚ１，Ｒｚ４は各々前記第３の梁状可撓部６と支持枠部４との連結端部、前記第３の梁状可撓部６′と支持枠部４との連結端部に形成されているため、前記第３、第４の梁状可撓部６，６′の捻れによる歪は実質的に作用せず、歪抵抗素子Ｒｚ１，Ｒｚ４の抵抗値は変化することはない。 As the weight portion 3 rotates in the positive direction of the X axis, the cross section of the fourth beam-like flexible portion 6 'is shown in FIG. 7 (c), (d), and (e). From the connecting part to the connecting part to the weight part 3 continuously rotating around the Z axis, that is, the fourth beam-like flexible part 6 'is twisted, so that tensile strain acts on Rz3 and the resistance value Rises. Similarly, since the third beam-like flexible portion 6 is also twisted, a tensile strain acts on Rz2 and the resistance value increases. Thereby, the balance of the bridge circuit of FIG. 6C is broken, and the midpoint potential (V1) between the strain resistance element Rz1 and the strain resistance element Rz3, and the midpoint potential between the strain resistance element Rz2 and the strain resistance element Rz4 ( Since a voltage difference from V2) occurs, a false signal as if acceleration is applied in the Z-axis direction, that is, another-axis sensitivity is generated. The strain resistance elements Rz1 and Rz4 are respectively connected to the connection end portion between the third beam-like flexible portion 6 and the support frame portion 4, and to the connection between the third beam-like flexible portion 6 ′ and the support frame portion 4. Since it is formed at the end, the strain caused by twisting of the third and fourth beam-like flexible portions 6 and 6 'does not substantially act, and the resistance values of the strain resistance elements Rz1 and Rz4 change. There is no.

また、図７（ｃ）に示すように、Ｘ軸の正方向への錘部３の回動に伴い、前記第３、第４の梁状可撓部６，６′が捻られるため、歪抵抗素子Ｒｙ２，Ｒｙ３には圧縮歪が作用して抵抗値が低下する。この時、図６（ｂ）のブリッジ回路は原理的には平衡状態を維持する。すなわち、歪抵抗素子Ｒｙ２，Ｒｙ３の抵抗値がともに△％だけ低下するとすれば、
Ｒｙ１・Ｒｙ３（１−△）−Ｒｙ４・Ｒｙ２（１−△）
＝（Ｒｙ１・Ｒｙ３−Ｒｙ２・Ｒｙ４）・（１−△）＝０
となるため、図６（ｂ）のブリッジ回路は平衡状態を維持し、歪抵抗素子Ｒｙ１と歪抵抗素子Ｒｙ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｙ２と歪抵抗素子Ｒｙ３との中点電位（Ｖ２）とは同一電位となる。これにより、Ｘ軸方向の加速度によりＹ軸方向の他軸感度が発生することはない。しかしながら、歪抵抗素子Ｒｙ１，Ｒｙ２，Ｒｙ３，Ｒｙ４の形成位置のバラツキやエッチング加工後に梁状可撓部に作用する残留歪等により、歪抵抗素子Ｒｙ２，Ｒｙ３の抵抗値の変化率△が異なる場合がある。この場合には、図６（ｂ）のブリッジ回路は平衡が破れ、歪抵抗素子Ｒｙ１と歪抵抗素子Ｒｙ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｙ２と歪抵抗素子Ｒｙ３との中点電位（Ｖ２）との電圧差が発生するため、あたかもＹ軸方向に加速度が印加されたかのような偽信号、すなわち他軸感度が発生することになる。 Further, as shown in FIG. 7C, the third and fourth beam-like flexible portions 6 and 6 ′ are twisted with the rotation of the weight portion 3 in the positive direction of the X-axis, so that the distortion is caused. Compressive strain acts on the resistance elements Ry2 and Ry3 and the resistance value decreases. At this time, the bridge circuit of FIG. 6B is maintained in an equilibrium state in principle. That is, if the resistance values of the strain resistance elements Ry2 and Ry3 are both reduced by Δ%,
Ry1 · Ry3 (1-Δ) -Ry4 · Ry2 (1-Δ)
= (Ry1, Ry3-Ry2, Ry4), (1-Δ) = 0
Therefore, the bridge circuit of FIG. 6B maintains an equilibrium state, and the midpoint potential (V1) between the strain resistance element Ry1 and the strain resistance element Ry4, and between the strain resistance element Ry2 and the strain resistance element Ry3. The point potential (V2) is the same potential. Thereby, the other-axis sensitivity in the Y-axis direction does not occur due to the acceleration in the X-axis direction. However, when the rate of change Δ of the resistance values of the strain resistance elements Ry2, Ry3 is different due to variations in the formation positions of the strain resistance elements Ry1, Ry2, Ry3, Ry4, residual strain acting on the beam-like flexible portion after the etching process, etc. There is. In this case, the bridge circuit of FIG. 6B is out of balance, and the midpoint potential (V1) between the strain resistance element Ry1 and the strain resistance element Ry4, and the midpoint between the strain resistance element Ry2 and the strain resistance element Ry3. Since a voltage difference from the potential (V2) is generated, a false signal as if acceleration is applied in the Y-axis direction, that is, the other-axis sensitivity is generated.

次に、従来の加速度センサの検出素子にＹ軸方向の加速度が印加された時には、錘部３はＹ軸方向に向く慣性力Ｆｙにより回動し、歪抵抗素子Ｒｙ２，Ｒｙ４には引張歪が作用して抵抗値が上昇し、歪抵抗素子Ｒｙ１，Ｒｙ３には圧縮歪が作用して抵抗値が低下する。これにより、図６（ｂ）のブリッジ回路の平衡が破れ、歪抵抗素子Ｒｙ１と歪抵抗素子Ｒｙ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｙ２と歪抵抗素子Ｒｙ３との中点電位（Ｖ２）との電圧差がＹ軸方向の加速度として検出される。 Next, when acceleration in the Y-axis direction is applied to the detection element of the conventional acceleration sensor, the weight portion 3 is rotated by the inertial force Fy directed in the Y-axis direction, and tensile strain is applied to the strain resistance elements Ry2 and Ry4. The resistance value rises by acting, and the strain value acts on the strain resistance elements Ry1 and Ry3 to lower the resistance value. Thereby, the balance of the bridge circuit of FIG. 6B is broken, and the midpoint potential (V1) between the strain resistance element Ry1 and the strain resistance element Ry4, and the midpoint potential between the strain resistance element Ry2 and the strain resistance element Ry3 ( The voltage difference from V2) is detected as the acceleration in the Y-axis direction.

また、Ｙ軸方向への錘部３の回動に伴い、前記第１、第２の梁状可撓部５，５′が捻られる。この時、歪抵抗素子Ｒｘ１，Ｒｘ２，Ｒｘ３，Ｒｘ４の形成位置が前記第１、第２の梁状可撓部５，５′の中心線上からずれていたり、エッチング加工後に梁状可撓部に残留歪が存在したりする場合には、図６（ａ）のブリッジ回路の平衡が破れ、歪抵抗素子Ｒｘ１と歪抵抗素子Ｒｘ４との中点電位（Ｖ１）と、歪抵抗素子Ｒｘ２と歪抵抗素子Ｒｘ３との中点電位（Ｖ２）との電圧差が発生するため、あたかもＸ軸方向に加速度が印加されたかのような偽信号、すなわち他軸感度が発生することになる。 Further, the first and second beam-like flexible portions 5 and 5 ′ are twisted with the rotation of the weight portion 3 in the Y-axis direction. At this time, the formation position of the strain resistance elements Rx1, Rx2, Rx3, Rx4 is shifted from the center line of the first and second beam-like flexible portions 5, 5 ', or after the etching process, When residual strain exists, the balance of the bridge circuit in FIG. 6A is broken, and the midpoint potential (V1) between the strain resistance element Rx1 and the strain resistance element Rx4, the strain resistance element Rx2, and the strain resistance. Since a voltage difference from the midpoint potential (V2) with respect to the element Rx3 is generated, a false signal as if acceleration is applied in the X-axis direction, that is, another-axis sensitivity is generated.

本発明は上記従来の課題を解決するもので、歪抵抗素子の形成位置のバラツキやエッチング加工後に梁状可撓部に残留歪があったしても、他軸感度が発生せず、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出できる３軸加速度センサを提供するものである。 The present invention solves the above-described conventional problems. Even if there is variation in the formation position of the strain resistance element or residual strain in the beam-shaped flexible portion after etching processing, no other-axis sensitivity occurs, and the X axis The present invention provides a triaxial acceleration sensor that can accurately detect acceleration in the triaxial direction including the Y axis and the Z axis.

上記目的を達成するために、本発明は以下の構成を有する。 In order to achieve the above object, the present invention has the following configuration.

請求項１に記載の発明は、ＸＹ平面に平行に置かれた基板と、前記基板の略中央部に設けられ加速度を受けて変位する第１の錘部と、前記第１の錘部を取り囲むように配置した支持枠部と、前記第１の錘部と支持枠部とを連結しＸ軸に平行な一対の梁状可撓部と、前記第１の錘部と支持枠部とを連結しＹ軸に平行な一対の梁状可撓部と、前記梁状可撓部上でかつ前記梁状可撓部と前記第１の錘部との連結端部に形成した歪抵抗素子とを備え、前記支持枠部内に、前記Ｘ軸に平行な一対の梁状可撓部の中心軸に関して略対称で、Ｘ軸に平行な一対の薄肉部を設けることにより、加速度を受けて変位する第２、第３の錘部を形成するとともに、前記支持枠部内に、前記Ｙ軸に平行な一対の梁状可撓部の中心軸に関して対称で、Ｙ軸に平行な一対の薄肉部を設けることにより、加速度を受けて変位する第４、第５の錘部を形成したもので、この構成によれば、Ｘ軸方向またはＹ軸方向のいずれか１つの軸方向の加速度が印加された時、この加速度が印加された軸に直交する梁状可撓部と、第２、第３または第４、第５の錘部が同方向に変位するため、前記梁状可撓部と錘部との連結端部に形成した歪抵抗素子に引張歪または圧縮歪が作用しないようにでき、これにより、他軸感度を発生させることなく、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出でき、かつ第１の錘部と、第２、第３または第４、第５の錘部が同方向に変位するため、加速度感度を向上させることができるという作用効果を有するものである。 According to the first aspect of the present invention, a substrate placed parallel to the XY plane, a first weight portion provided at a substantially central portion of the substrate and displaced by acceleration, and the first weight portion are surrounded. The support frame part arranged in this way, the first weight part and the support frame part are connected, a pair of beam-like flexible parts parallel to the X axis, and the first weight part and the support frame part are connected. A pair of beam-like flexible portions parallel to the Y-axis, and a strain resistance element formed on the beam-like flexible portion and at a connection end portion between the beam-like flexible portion and the first weight portion. Provided with a pair of thin-walled portions that are substantially symmetrical with respect to the central axis of the pair of beam-like flexible portions parallel to the X-axis and parallel to the X-axis in the support frame portion. Forming a third weight portion and a pair of beam-shaped flexible portions symmetrical to the central axis of the pair of beam-shaped flexible portions parallel to the Y axis and parallel to the Y axis in the support frame portion; By providing the flesh portion, the fourth and fifth weight portions that are displaced by the acceleration are formed. According to this configuration, the acceleration in one of the X-axis direction and the Y-axis direction can be increased. When the beam is applied, the beam-shaped flexible portion perpendicular to the axis to which the acceleration is applied and the second, third, fourth, and fifth weight portions are displaced in the same direction. Tensile strain or compressive strain is prevented from acting on the strain resistance element formed at the connection end portion between the weight portion and the weight portion, so that it is possible to form the X-axis, the Y-axis, and the Z-axis without generating other-axis sensitivity. The acceleration in the axial direction can be accurately detected, and the first weight part and the second, third, fourth, and fifth weight parts are displaced in the same direction, so that acceleration sensitivity can be improved. It has an effect.

本発明の請求項２に記載の発明は、特に、前記歪抵抗素子と電気的に接続された電極パッドを前記支持枠部の上面で、前記薄肉部および前記第２、第３、第４、第５の錘部以外の位置に設けたもので、この構成によれば、前記電極パッドと外部電極を接続する際、もしくは、他の基板等への実装・接着を行う際に応力が印加された時、前記薄肉部が撓むため、前記梁状可撓部および前記第２、第３、第４、第５の錘部への応力印加を妨げることができ、これにより、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出できるという作用効果を有するものである。 In the invention according to claim 2 of the present invention, in particular, an electrode pad electrically connected to the strain resistance element is formed on the upper surface of the support frame portion, and the thin portion and the second, third, fourth, This is provided at a position other than the fifth weight portion. According to this configuration, stress is applied when the electrode pad and the external electrode are connected, or when mounting / bonding to another substrate or the like. Since the thin portion bends, the application of stress to the beam-like flexible portion and the second, third, fourth, and fifth weight portions can be prevented. This has the effect of being able to accurately detect the acceleration in the three-axis direction including the axis and the Z-axis.

本発明の請求項３に記載の発明は、特に、前記薄肉部に切り欠き部を設けたもので、この構成によれば、前記薄肉部の剛性が下がるため、Ｘ軸方向またはＹ軸方向のいずれか１つの軸方向の加速度が印加された時、前記第２、第３、第４、第５の錘部の変位量を増加させることができ、これにより、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度感度をさらに向上させることができるという作用効果を有するものである。 In the invention according to claim 3 of the present invention, in particular, a notch portion is provided in the thin portion. According to this configuration, the rigidity of the thin portion is lowered, so that the X-axis direction or the Y-axis direction is reduced. When the acceleration in any one of the axial directions is applied, the amount of displacement of the second, third, fourth, and fifth weight portions can be increased, whereby the X axis, the Y axis, and the Z axis This has the effect of further improving the acceleration sensitivity in the three-axis direction.

以上のように本発明の３軸加速度センサは、ＸＹ平面に平行に置かれた基板と、前記基板の略中央部に設けられ加速度を受けて変位する第１の錘部と、前記第１の錘部を取り囲むように配置した支持枠部と、前記第１の錘部と支持枠部とを連結しＸ軸に平行な一対の梁状可撓部と、前記第１の錘部と支持枠部とを連結しＹ軸に平行な一対の梁状可撓部と、前記梁状可撓部上でかつ前記梁状可撓部と前記第１の錘部との連結端部に形成した歪抵抗素子とを備え、前記支持枠部内に、前記Ｘ軸に平行な一対の梁状可撓部の中心軸に関して略対称で、Ｘ軸に平行な一対の薄肉部を設けることにより、加速度を受けて変位する第２、第３の錘部を形成するとともに、前記支持枠部内に、前記Ｙ軸に平行な一対の梁状可撓部の中心軸に関して対称で、Ｙ軸に平行な一対の薄肉部を設けることにより、加速度を受けて変位する第４、第５の錘部を形成したもので、Ｘ軸方向またはＹ軸方向のいずれか１つの軸方向の加速度が印加された時、この加速度が印加された軸に直交する梁状可撓部と、第２、第３または第４、第５の錘部が同方向に変位するため、前記梁状可撓部と錘部との連結端部に形成した歪抵抗素子に引張歪または圧縮歪が作用しないようにでき、これにより、他軸感度を発生させることなく、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出できるとともに、第１の錘部と、第２、第３または第４、第５の錘部が同方向に変位するため、加速度感度を向上させることができるという優れた効果を奏するものである。 As described above, the three-axis acceleration sensor according to the present invention includes the substrate placed in parallel with the XY plane, the first weight portion that is provided at a substantially central portion of the substrate and is displaced by the acceleration, and the first weight sensor. A support frame portion disposed so as to surround the weight portion; a pair of beam-like flexible portions that connect the first weight portion and the support frame portion and are parallel to the X axis; and the first weight portion and the support frame A pair of beam-shaped flexible portions that are connected to each other and parallel to the Y-axis, and a strain formed on the beam-shaped flexible portion and at a connection end portion between the beam-shaped flexible portion and the first weight portion. A resistance element, and a pair of thin portions parallel to the X-axis that are substantially symmetrical with respect to the central axis of the pair of beam-like flexible portions parallel to the X-axis in the support frame. The second and third weight portions that are displaced in the direction are formed, and the support frame portion is symmetrical with respect to the central axis of the pair of beam-like flexible portions parallel to the Y axis, and Y By providing a pair of thin wall parts parallel to each other, the fourth and fifth weight parts that are displaced by the acceleration are formed, and the acceleration in either the X-axis direction or the Y-axis direction is applied. The beam-like flexible part perpendicular to the axis to which the acceleration is applied and the second, third, fourth, and fifth weight parts are displaced in the same direction, Tensile strain or compressive strain can be prevented from acting on the strain resistance element formed at the connection end portion with the weight portion, so that the three axes including the X axis, the Y axis, and the Z axis can be generated without generating other axis sensitivity. The acceleration in the direction can be accurately detected, and the first weight part and the second, third, fourth, and fifth weight parts are displaced in the same direction, so that the acceleration sensitivity can be improved. There is an effect.

（ａ）本発明の実施の形態１における３軸加速度センサの検出素子の上面図、（ｂ）（ａ）におけるａ−ａ線断面図、（ｃ）（ａ）におけるｂ−ｂ線断面図(A) Top view of detection element of triaxial acceleration sensor according to Embodiment 1 of the present invention, (b) Aa line sectional view in (a), (c) bb line sectional view in (a) （ａ）本発明の実施の形態１における３軸加速度センサの検出素子にＸ軸方向の加速度が印加された時の上面図、（ｂ）（ａ）のａ−ａ線断面図、（ｃ）（ａ）のｃ−ｃ線断面図、（ｄ）（ａ）のｄ−ｄ線断面図、（ｅ）（ａ）のｂ−ｂ線断面図(A) Top view when acceleration in the X-axis direction is applied to the detection element of the three-axis acceleration sensor according to Embodiment 1 of the present invention, (b) Aa line cross-sectional view of (a), (c) (A) cc line sectional view, (d) (a) dd line sectional view, (e) (a) bb line sectional view （ａ）本発明の実施の形態２における３軸加速度センサの検出素子の上面図、（ｂ）（ａ）において検出素子内部方向に応力が印加された時のｅ−ｅ線断面図(A) Top view of detection element of triaxial acceleration sensor according to Embodiment 2 of the present invention, (b) ee line cross-sectional view when stress is applied in the detection element internal direction in (a) （ａ）−（ｃ）本発明の実施の形態３における３軸加速度センサの検出素子の上面図(A)-(c) Top view of detection element of triaxial acceleration sensor in Embodiment 3 of the present invention. （ａ）従来の加速度センサの検出素子の上面図、（ｂ）図５（ａ）の検出素子におけるＡ−Ａ線断面図(A) Top view of detection element of conventional acceleration sensor, (b) AA line sectional view of detection element in FIG. 5 (a) （ａ）前記従来の加速度センサの検出素子に形成した歪抵抗素子Ｒｘ１，Ｒｘ２，Ｒｘ３，Ｒｘ４により構成されるブリッジ回路図、（ｂ）同検出素子に形成した歪抵抗素子Ｒｙ１，Ｒｙ２，Ｒｙ３，Ｒｙ４により構成されるブリッジ回路図、（ｃ）同検出素子に形成した歪抵抗素子Ｒｚ１，Ｒｚ２，Ｒｚ３，Ｒｚ４により構成されるブリッジ回路図(A) Bridge circuit diagram composed of strain resistance elements Rx1, Rx2, Rx3, Rx4 formed on the detection elements of the conventional acceleration sensor, (b) Strain resistance elements Ry1, Ry2, Ry3 formed on the detection elements. Bridge circuit diagram composed of Ry4, (c) Bridge circuit diagram composed of strain resistance elements Rz1, Rz2, Rz3, Rz4 formed in the detection element （ａ）従来の加速度センサの検出素子にＸ軸正方向の加速度が印加された時の上面図、（ｂ）（ａ）のＡ−Ａ線断面図、（ｃ）（ａ）のＢ−Ｂ線断面図、（ｄ）（ａ）のＣ−Ｃ線断面図、（ｅ）（ａ）のＤ−Ｄ線断面図(A) Top view when acceleration in the positive direction of the X-axis is applied to the detection element of the conventional acceleration sensor, (b) AA line sectional view of (a), (c) BB of (a) Line sectional view, (d) CC line sectional view of (a), (e) DD line sectional view of (a)

（実施の形態１）
以下、実施の形態１を用いて、本発明の特に請求項１に記載の発明について説明する。図１（ａ）は本発明の実施の形態１における３軸加速度センサの検出素子の上面図、図１（ｂ）は図１（ａ）の検出素子におけるＸ軸に平行なａ−ａ線断面図、図１（ｃ）は図１（ａ）の検出素子におけるＸ軸に平行なｂ−ｂ線断面図を示す。図１（ａ）−（ｃ）において、２１はＸＹ平面に平行に配置されたシリコン単結晶基板であり、該基板２１の底面側をエッチング処理するとともに貫通孔２２を形成することにより、厚肉部からなる錘部２３とそれを囲むように配された支持枠部２４と、薄肉で該錘部２３および支持枠部２４とを接続するＸ軸に平行な第１、第２の梁状可撓部２５，２５′と、薄肉で該錘部３および支持枠部４とを接続するＹ軸に平行な第３、第４の梁状可撓部２６，２６′とが形成されている。前記第１の梁状可撓部２５と支持枠部２４との連結端部には歪抵抗素子Ｒｘ２１を、前記第１の梁状可撓部２５と錘部２３との連結端部には歪抵抗素子Ｒｘ２２を形成している。また、前記第２の梁状可撓部２５′と錘部２３との連結端部には歪抵抗素子Ｒｘ２３を、前記第２の梁状可撓部２５′と支持枠部２４との連結端部には歪抵抗素子Ｒｘ２４を形成している。そして、前記歪抵抗素子Ｒｘ２１，Ｒｘ２２，Ｒｘ２３，Ｒｘ２４を前記第１、第２の梁状可撓部２５，２５′の中心線上に配置している。同様にして、前記第３の梁状可撓部２６と支持枠部２４との連結端部には歪抵抗素子Ｒｙ２１，Ｒｚ２１を、前記第３の梁状可撓部２６と錘部２３との連結端部には歪抵抗素子Ｒｙ２２，Ｒｚ２２を形成している。また、前記第３の梁状可撓部２６′と錘部２３との連結端部には歪抵抗素子Ｒｙ２３，Ｒｚ２３を、前記第３の梁状可撓部２６′と支持枠部２４との連結端部には歪抵抗素子Ｒｙ２４，Ｒｚ２４を形成している。そして、前記歪抵抗素子Ｒｙ２１，Ｒｙ２２，Ｒｙ２３，Ｒｙ２４と前記歪抵抗素子Ｒｚ２１，Ｒｚ２２，Ｒｚ２３，Ｒｚ２４とを前記第３、第４の梁状可撓部２６，２６′の中心線の両側にそれぞれ１列に配置している。前記歪抵抗素子としてはシリコン単結晶基板の所定の位置にホウ素等の不純物をイオン注入して形成した半導体ピエゾ抵抗または酸化亜鉛、酸化クロム、酸化ルテニウムなどを蒸着して構成した酸化物抵抗を用いることができる。また、前記各歪抵抗素子は金属配線（図示せず）により図６に示したものと同様のブリッジ回路を構成している。２７，２７′，２８，２８′は前記支持枠部２４内に、前記Ｘ軸に平行な一対の梁状可撓部２５，２５′の中心軸に関して略対称で、Ｘ軸に平行に設けられた一対の薄肉部であり、３１，３２は前記薄肉部２７，２７′，２８，２８′を設けることによって形成された、加速度を受けて変位する第２、第３の錘部である。また、２９，２９′，３０，３０′は前記支持枠部２４内に、前記Ｙ軸に平行な一対の梁状可撓部２６，２６′の中心軸に関して略対称で、Ｙ軸に平行に設けられた一対の薄肉部であり、３３，３４は前記薄肉部２９，２９′，３０，３０′を設けることによって形成された、加速度を受けて変位する第４、第５の錘部である。 (Embodiment 1)
Hereinafter, the first aspect of the present invention will be described with reference to the first embodiment. FIG. 1A is a top view of the detection element of the triaxial acceleration sensor according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view taken along the line aa in the detection element of FIG. FIG. 1 and FIG. 1C are cross-sectional views taken along the line bb parallel to the X axis in the detection element of FIG. In FIGS. 1A to 1C, reference numeral 21 denotes a silicon single crystal substrate arranged in parallel with the XY plane. The bottom surface side of the substrate 21 is etched and a through-hole 22 is formed to increase the thickness. First and second beam-like members that are thin and parallel to the X-axis connecting the weight portion 23 and the support frame portion 24. The flexible portions 25 and 25 ′ and the third and fourth beam-like flexible portions 26 and 26 ′ which are thin and are parallel to the Y axis and connect the weight portion 3 and the support frame portion 4 are formed. The strain resistance element Rx21 is connected to the connecting end portion between the first beam-shaped flexible portion 25 and the support frame portion 24, and the connecting end portion between the first beam-shaped flexible portion 25 and the weight portion 23 is strained. A resistance element Rx22 is formed. Further, a strain resistance element Rx23 is connected to the connection end portion between the second beam-shaped flexible portion 25 ′ and the weight portion 23, and the connection end between the second beam-shaped flexible portion 25 ′ and the support frame portion 24. A strain resistance element Rx24 is formed in the portion. The strain resistance elements Rx21, Rx22, Rx23, Rx24 are arranged on the center lines of the first and second beam-like flexible portions 25, 25 ′. Similarly, the strain resistance elements Ry21 and Rz21 are connected to the connecting end portion of the third beam-like flexible portion 26 and the support frame portion 24, and the third beam-like flexible portion 26 and the weight portion 23 are connected. Strain resistance elements Ry22 and Rz22 are formed at the connection end. Further, strain resistance elements Ry23 and Rz23 are provided at the connecting end portion between the third beam-like flexible portion 26 'and the weight portion 23, and the third beam-like flexible portion 26' and the support frame portion 24 are connected to each other. Strain resistance elements Ry24 and Rz24 are formed at the connection end. The strain resistance elements Ry21, Ry22, Ry23, Ry24 and the strain resistance elements Rz21, Rz22, Rz23, Rz24 are respectively arranged on both sides of the center line of the third and fourth beam-like flexible portions 26, 26 '. Arranged in one row. As the strain resistance element, a semiconductor piezoresistor formed by ion-implanting impurities such as boron into a predetermined position of a silicon single crystal substrate or an oxide resistor configured by depositing zinc oxide, chromium oxide, ruthenium oxide or the like is used. be able to. Each of the strain resistance elements constitutes a bridge circuit similar to that shown in FIG. 6 by metal wiring (not shown). 27, 27 ′, 28, 28 ′ are provided in the support frame 24 so as to be substantially symmetrical with respect to the central axis of the pair of beam-like flexible portions 25, 25 ′ parallel to the X axis and parallel to the X axis. A pair of thin portions 31 and 32 are second and third weight portions which are formed by providing the thin portions 27, 27 ', 28 and 28' and which are displaced by acceleration. 29, 29 ', 30, 30' are substantially symmetrical with respect to the central axis of the pair of beam-like flexible portions 26, 26 'parallel to the Y axis in the support frame 24, and parallel to the Y axis. A pair of thin portions provided, and 33 and 34 are fourth and fifth weight portions formed by providing the thin portions 29, 29 ', 30, and 30', which are displaced by acceleration. .

図２（ａ）は本発明の実施の形態１における３軸加速度センサの検出素子にＸ軸方向の加速度が印加された時の上面図、図２（ｂ）は図２（ａ）のＸ軸に平行なａ−ａ線での断面図である。図２（ｂ）において、錘部２３はＸ軸の正方向に向く慣性力Ｆｘにより回動し、歪抵抗素子Ｒｘ２１，Ｒｘ２３には引張歪が作用して抵抗値が上昇し、歪抵抗素子Ｒｘ２２，Ｒｘ２４には圧縮歪が作用して抵抗値が低下する。これにより、歪抵抗素子Ｒｘ２１，Ｒｘ２２，Ｒｘ２３，Ｒｘ２４で構成されるブリッジ回路の平衡が破れ、歪抵抗素子Ｒｘ２１と歪抵抗素子Ｒｘ２４との中点電位と、歪抵抗素子Ｒｘ２２と歪抵抗素子Ｒｘ２３との中点電位との電圧差がＸ軸方向の加速度として検出される。 2A is a top view when acceleration in the X-axis direction is applied to the detection element of the triaxial acceleration sensor according to Embodiment 1 of the present invention, and FIG. 2B is the X-axis of FIG. 2A. It is sectional drawing in the aa line parallel to this. In FIG. 2B, the weight portion 23 is rotated by an inertial force Fx directed in the positive direction of the X-axis, tensile strain acts on the strain resistance elements Rx21 and Rx23, and the resistance value increases, and the strain resistance element Rx22. , Rx24 is subjected to compressive strain to reduce the resistance value. As a result, the balance of the bridge circuit composed of the strain resistance elements Rx21, Rx22, Rx23, and Rx24 is broken, and the midpoint potential between the strain resistance element Rx21 and the strain resistance element Rx24, the strain resistance element Rx22, and the strain resistance element Rx23 A voltage difference from the midpoint potential is detected as acceleration in the X-axis direction.

図２（ｃ）は図２（ａ）の第４の梁状可撓部２６′と錘部２３との連結部近傍におけるＸ軸に平行なｃ−ｃ線断面図、図２（ｄ）は図２（ａ）の第４の梁状可撓部２６′と支持枠部２４との連結部近傍におけるＸ軸に平行なｄ−ｄ線断面図、図２（ｅ）は図２（ａ）の支持枠部２４上で、かつ、第４の薄肉部３０，３０′および第５の錘部３４におけるＸ軸に平行なｂ−ｂ線断面図である。 2C is a cross-sectional view taken along the line cc parallel to the X axis in the vicinity of the connecting portion between the fourth beam-like flexible portion 26 ′ and the weight portion 23 in FIG. 2A, and FIG. FIG. 2A is a cross-sectional view taken along the line dd in the vicinity of the connecting portion between the fourth beam-shaped flexible portion 26 ′ and the support frame portion 24 in FIG. 2A, and FIG. FIG. 6 is a cross-sectional view taken along line bb parallel to the X axis of the fourth thin portion 30, 30 ′ and the fifth weight portion 34 on the support frame portion 24.

図２（ｃ）に示すように錘部２３のＸ軸の正方向への回動に伴い第４の梁状可撓部２６′は錘部２３との連結部においてＹ軸の周りに回転する。ここで、従来の加速度センサの検出素子においては、第４の梁状可撓部２６′は支持枠部２４との連結部近傍においてＹ軸の周りに回転することができない。これにより、第４の梁状可撓部２６′は錘部２３との接続部と、支持枠部２４との接続部との間で捻れることになる。しかしながら、本発明の実施の形態１における３軸加速度センサの検出素子においては、支持枠部２４に第４の薄肉部３０，３０′を設けているため、この第４の薄肉部３０，３０′が第１、第２の梁状可撓部２５，２５′と同方向に変位し、第１の錘部２３における上面と、第５の錘部３４における上面とが同一平面となるため、この捻れは第４の梁状可撓部２６′内で発生することがない。これにより、歪抵抗素子Ｒｚ２４には引張または圧縮歪が作用せず抵抗値は変化することはない。同様に、前記第３の梁状可撓部２６上の歪抵抗素子Ｒｚ２１にも引張または圧縮歪が作用せず抵抗値は変化することはない。これにより、歪抵抗素子Ｒｚ２１，Ｒｚ２２，Ｒｚ２３，Ｒｚ２４で構成されるブリッジ回路は平衡状態を維持するため、他軸感度が発生することがない。 As shown in FIG. 2 (c), the fourth beam-like flexible portion 26 ′ rotates around the Y axis at the connecting portion with the weight portion 23 as the weight portion 23 rotates in the positive direction of the X axis. . Here, in the detection element of the conventional acceleration sensor, the fourth beam-like flexible portion 26 ′ cannot rotate around the Y axis in the vicinity of the connecting portion with the support frame portion 24. As a result, the fourth beam-like flexible portion 26 ′ is twisted between the connection portion with the weight portion 23 and the connection portion with the support frame portion 24. However, in the detection element of the triaxial acceleration sensor according to the first embodiment of the present invention, the fourth thin portion 30, 30 'is provided in the support frame portion 24. Therefore, the fourth thin portion 30, 30' is provided. Is displaced in the same direction as the first and second beam-like flexible portions 25 and 25 ', and the upper surface of the first weight portion 23 and the upper surface of the fifth weight portion 34 are in the same plane. Twist does not occur in the fourth beam-like flexible part 26 '. As a result, no tensile or compressive strain acts on the strain resistance element Rz24, and the resistance value does not change. Similarly, no tensile or compressive strain acts on the strain resistance element Rz21 on the third beam-shaped flexible portion 26, and the resistance value does not change. As a result, the bridge circuit composed of the strain resistance elements Rz21, Rz22, Rz23, and Rz24 maintains an equilibrium state, so that no other-axis sensitivity occurs.

また、図２（ｃ）−（ｅ）に示すように、錘部２３がＸ軸の正方向へ回動しても、前記第３、第４の梁状可撓部２６，２６′上に形成した歪抵抗素子Ｒｙ２１，Ｒｙ２４には歪が作用しないため抵抗値は変化せず、これにより歪抵抗素子Ｒｙ２１，Ｒｙ２２，Ｒｙ２３，Ｒｙ２４の形成位置のバラツキやエッチング加工後に梁状可撓部に作用する残留歪等により、歪抵抗素子Ｒｙ２１，Ｒｙ２４の抵抗値の変化率△が異なったとしても歪抵抗素子Ｒｙ２１，Ｒｙ２２，Ｒｙ２３，Ｒｙ２４で構成されるブリッジ回路は平衡状態を維持し、他軸感度が発生することがない。 Further, as shown in FIGS. 2C to 2E, even if the weight portion 23 is rotated in the positive direction of the X axis, the third and fourth beam-like flexible portions 26 and 26 'are not moved. Since the strain does not act on the formed strain resistance elements Ry21 and Ry24, the resistance value does not change. This causes variations in the formation positions of the strain resistance elements Ry21, Ry22, Ry23, and Ry24 and acts on the beam-shaped flexible portion after etching processing. Even if the change rate Δ of the resistance value of the strain resistance elements Ry21, Ry24 differs due to the residual strain, etc., the bridge circuit composed of the strain resistance elements Ry21, Ry22, Ry23, Ry24 maintains the equilibrium state and the other-axis sensitivity Will not occur.

また、図２（ｅ）に示すように、Ｘ軸方向の加速度が印加されると、第１の錘部２３がＸ軸方向に回動するとともに、支持枠部２４に形成された第５の錘部３４は、第１の錘部２３と同方向に変位するため、Ｘ軸に印加される単位加速度あたりに変位する錘部の質量が、第１の錘部２３のみの場合と比較して増加する。同様に、第４の錘部３３も、第１の錘部２３と同方向に変位する。それにより、加速度検出素子のＸ軸方向の加速度感度を向上させることができる。 Further, as shown in FIG. 2E, when acceleration in the X-axis direction is applied, the first weight portion 23 rotates in the X-axis direction and the fifth weight formed on the support frame portion 24. Since the weight part 34 is displaced in the same direction as the first weight part 23, the mass of the weight part displaced per unit acceleration applied to the X-axis is smaller than that of the first weight part 23 alone. To increase. Similarly, the fourth weight part 33 is also displaced in the same direction as the first weight part 23. Thereby, the acceleration sensitivity of the acceleration detection element in the X-axis direction can be improved.

次に、本発明の実施の形態１における３軸加速度センサの検出素子にＹ軸方向の加速度が印加されると、錘部２３はＹ軸方向に向く慣性力Ｆｙにより回動し、歪抵抗素子Ｒｙ２２，Ｒｙ２４には引張歪が作用して抵抗値が上昇し、歪抵抗素子Ｒｙ２１，Ｒｙ２３には圧縮歪が作用して抵抗値が低下する。これにより、歪抵抗素子Ｒｙ２１，Ｒｙ２２，Ｒｙ２３，Ｒｙ２４で構成されるブリッジ回路の平衡が破れ、歪抵抗素子Ｒｙ２１と歪抵抗素子Ｒｙ２４との中点電位と、歪抵抗素子Ｒｙ２２と歪抵抗素子Ｒｙ２３との中点電位との電圧差がＹ軸方向の加速度として検出される。 Next, when acceleration in the Y-axis direction is applied to the detection element of the triaxial acceleration sensor according to Embodiment 1 of the present invention, the weight portion 23 is rotated by the inertial force Fy directed in the Y-axis direction, and the strain resistance element Tensile strain acts on Ry22 and Ry24 to increase the resistance value, and compressive strain acts on the strain resistance elements Ry21 and Ry23 to decrease the resistance value. As a result, the balance of the bridge circuit composed of the strain resistance elements Ry21, Ry22, Ry23, and Ry24 is broken, and the midpoint potential between the strain resistance elements Ry21 and Ry24, the strain resistance elements Ry22, and the strain resistance elements Ry23, A voltage difference from the midpoint potential is detected as acceleration in the Y-axis direction.

錘部２３がＹ軸の正方向へ回動しても、支持枠部２４には第１、第２の薄肉部２７，２７′，２８，２８′が設けられているため、本発明の実施の形態１における３軸加速度センサの検出素子にＸ軸正方向の加速度が印加された時と同様にして、第１、第２の梁状可撓部２５，２５′には捻れが発生することがなく、前記第１、第２の梁状可撓部２５，２５′上に形成した歪抵抗素子Ｒｘ２１，Ｒｘ２４には歪が作用しないため抵抗値は変化せず、これにより歪抵抗素子Ｒｘ２１，Ｒｘ２４の形成位置のバラツキやエッチング加工後に梁状可撓部に作用する残留歪等により、歪抵抗素子Ｒｘ２１，Ｒｘ２４の抵抗値の変化率△が異なったとしても歪抵抗素子Ｒｘ２１，Ｒｘ２２，Ｒｘ２３，Ｒｘ２４で構成されるブリッジ回路は平衡状態を維持し、他軸感度が発生することがない。 Even if the weight portion 23 is rotated in the positive direction of the Y axis, the support frame portion 24 is provided with the first and second thin portions 27, 27 ', 28, 28'. In the same manner as when the X-axis positive direction acceleration is applied to the detection element of the three-axis acceleration sensor in the first embodiment, twisting occurs in the first and second beam-like flexible portions 25 and 25 '. The strain resistance elements Rx21 and Rx24 formed on the first and second beam-like flexible portions 25 and 25 'are not subjected to strain, so that the resistance value does not change. Even if the change rate Δ of the resistance values of the strain resistance elements Rx21, Rx24 varies due to variations in the formation position of the Rx24 and residual strain acting on the beam-shaped flexible portion after the etching process, the strain resistance elements Rx21, Rx22, Rx23, The bridge circuit composed of Rx24 maintains a balanced state. And, axis sensitivity does not occur.

また、Ｙ軸方向の加速度が印加されると、第１の錘部２３がＹ軸方向に回動するとともに、支持枠部２４に形成された第２、第３の錘部３１，３２は、第１の錘部２３と同方向に変位するため、Ｙ軸に印加される単位加速度あたりに変位する錘部の質量が、第１の錘部２３のみの場合と比較して増加する。それにより、加速度検出素子のＹ軸方向の加速度感度を向上させることができる。 When acceleration in the Y-axis direction is applied, the first weight portion 23 rotates in the Y-axis direction, and the second and third weight portions 31 and 32 formed on the support frame portion 24 are Since the first weight part 23 is displaced in the same direction, the mass of the weight part displaced per unit acceleration applied to the Y axis is increased as compared with the case of only the first weight part 23. Thereby, the acceleration sensitivity of the acceleration detection element in the Y-axis direction can be improved.

このように、本発明の実施の形態１における３軸加速度センサの検出素子においては、Ｘ軸方向またはＹ軸方向のいずれか１つの軸方向の加速度が印加された時、加速度が印加された軸方向に、支持枠部に設けられた薄肉部が変位することで、この加速度が印加された軸に直交する他の梁状可撓部には捻れが発生せず、前記梁状可撓部と錘部との連結端部に形成した歪抵抗素子に引張歪または圧縮歪が作用しないようにでき、これにより、他軸感度を発生させることなく、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出でき、かつ、支持枠部に形成された第２、第３、第４、第５の錘部が加速度印加方向に対して、第１の錘部と同方向に変位するため、Ｘ軸およびＹ軸方向の加速度感度を向上することができ、これにより、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出できるものである。 As described above, in the detection element of the three-axis acceleration sensor according to Embodiment 1 of the present invention, when the acceleration in one of the X-axis direction and the Y-axis direction is applied, the axis to which the acceleration is applied is applied. In the direction, the thin-walled portion provided in the support frame portion is displaced, so that the other beam-like flexible portions orthogonal to the axis to which the acceleration is applied are not twisted, and the beam-like flexible portions and Tensile strain or compressive strain can be prevented from acting on the strain resistance element formed at the connection end portion with the weight portion, so that the three axes including the X axis, the Y axis, and the Z axis can be generated without generating other axis sensitivity. The acceleration in the direction can be accurately detected, and the second, third, fourth, and fifth weights formed on the support frame are displaced in the same direction as the first weight with respect to the acceleration application direction. Therefore, the acceleration sensitivity in the X-axis and Y-axis directions can be improved. Axis, in which the acceleration in three axial directions consisting of the Z-axis can be accurately detected.

（実施の形態２）
以下、実施の形態２を用いて、本発明の特に請求項２に記載の発明についてさらに説明する。図３（ａ）は本発明の実施の形態２における３軸加速度センサの検出素子の上面図、図３（ｂ）は図３（ａ）におけるＸ軸に平行なｅ−ｅ線断面図である。なお、この本発明の実施の形態２においては、上記した本発明の実施の形態１の構成と同様の構成を有するものについては、同一符号を付しており、その説明は省略する。 (Embodiment 2)
Hereinafter, the second aspect of the present invention will be further described with reference to the second embodiment. FIG. 3A is a top view of the detection element of the triaxial acceleration sensor according to Embodiment 2 of the present invention, and FIG. 3B is a cross-sectional view taken along the line ee parallel to the X axis in FIG. . In the second embodiment of the present invention, components having the same configuration as the configuration of the first embodiment of the present invention described above are denoted by the same reference numerals, and the description thereof is omitted.

図３（ａ）において、本発明の実施の形態２が上記した本発明の実施の形態１と相違する点は、歪抵抗素子と電気的に接続された電極パッド３５を支持枠部２４の上面で、薄肉部２７，２７′，２８，２８′，２９，２９′，３０，３０′および第２、第３、第４、第５の錘部３１〜３４以外の箇所に設けた点である。 In FIG. 3A, the second embodiment of the present invention differs from the first embodiment of the present invention described above in that the electrode pad 35 electrically connected to the strain resistance element is connected to the upper surface of the support frame portion 24. In this case, the thin portions 27, 27 ', 28, 28', 29, 29 ', 30, 30' and the second, third, fourth and fifth weight portions 31 to 34 are provided. .

本発明の実施の形態２における３軸加速度センサにおいては、本発明の実施の形態１における３軸加速度センサと同様に他軸感度を発生させることがなく、かつ、加速度感度を向上させることができるとともに、さらに梁状可撓部２５，２５′，２６，２６′および歪抵抗素子Ｒｘ２１〜Ｒｘ２４，Ｒｙ２１〜Ｒｙ２４，Ｒｚ２１〜Ｒｚ２４に応力を伝達させないようにでき、これにより、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出できるものである。 In the triaxial acceleration sensor according to the second embodiment of the present invention, the other-axis sensitivity is not generated and the acceleration sensitivity can be improved similarly to the triaxial acceleration sensor according to the first embodiment of the present invention. In addition, it is possible to prevent stress from being transmitted to the beam-like flexible portions 25, 25 ′, 26, 26 ′ and the strain resistance elements Rx21 to Rx24, Ry21 to Ry24, Rz21 to Rz24. The acceleration in the three-axis direction composed of the Z axis can be accurately detected.

以下に、この点について説明する。 This point will be described below.

図３（ａ）に示す本発明の実施の形態２において、Ｘ軸方向の加速度が印加されると、本発明の実施の形態１における３軸加速度センサの検出素子の場合と同様にして、支持枠部２４に設けられた第３、第４の薄肉部２９，２９′，３０，３０′が第１、第２の梁状可撓部２５，２５′と同方向に変位し、第１の錘部２３における上面と、第４、第５の錘部３３，３４における上面とが同一平面となるため、第３、第４の梁状可撓部２６′内で捻れが発生することがない。これにより、歪抵抗素子Ｒｚ２１，Ｒｚ２４およびＲｙ２１，Ｒｙ２４には引張または圧縮歪が作用せず抵抗値は変化しない。これにより、歪抵抗素子Ｒｚ２１，Ｒｚ２２，Ｒｚ２３，Ｒｚ２４およびＲｙ２１，Ｒｙ２２，Ｒｙ２３，Ｒｙ２４で構成されるブリッジ回路は平衡状態を維持するため、他軸感度が発生することがない。 In the second embodiment of the present invention shown in FIG. 3 (a), when acceleration in the X-axis direction is applied, the support is performed in the same manner as the detection element of the three-axis acceleration sensor in the first embodiment of the present invention. The third and fourth thin portions 29, 29 ', 30, 30' provided in the frame portion 24 are displaced in the same direction as the first and second beam-like flexible portions 25, 25 ', and the first Since the upper surface of the weight portion 23 and the upper surfaces of the fourth and fifth weight portions 33 and 34 are on the same plane, no twist is generated in the third and fourth beam-like flexible portions 26 '. . Thereby, tensile resistance or compressive strain does not act on the strain resistance elements Rz21, Rz24 and Ry21, Ry24, and the resistance value does not change. As a result, the bridge circuit composed of the strain resistance elements Rz21, Rz22, Rz23, Rz24 and Ry21, Ry22, Ry23, Ry24 maintains an equilibrium state, so that no other-axis sensitivity occurs.

また、本発明の実施の形態２において、Ｙ軸正方向の加速度が印加された時も、本発明の実施の形態１における３軸加速度センサの検出素子の場合と同様にして、錘部２３がＹ軸の正方向へ回動しても、支持枠部２４には第１、第２の薄肉部２７，２７′，２８，２８′が設けられているため、第１、第２の梁状可撓部２５，２５′には捻れが発生することがなく、前記第１、第２の梁状可撓部２５，２５′上に形成した歪抵抗素子Ｒｘ２１，Ｒｘ２４には歪が作用しないため抵抗値は変化しない。これにより、歪抵抗素子Ｒｘ２１，Ｒｘ２２，Ｒｘ２３，Ｒｘ２４で構成されるブリッジ回路は平衡状態を維持し、他軸感度が発生することがない。 Further, in the second embodiment of the present invention, when acceleration in the Y-axis positive direction is applied, the weight portion 23 is moved as in the case of the detection element of the three-axis acceleration sensor in the first embodiment of the present invention. Even if the support frame 24 is rotated in the positive direction of the Y-axis, the first and second thin beam portions 27, 27 ', 28, 28' are provided on the support frame portion 24. The flexible portions 25 and 25 'are not twisted, and no strain acts on the strain resistance elements Rx21 and Rx24 formed on the first and second beam-like flexible portions 25 and 25'. The resistance value does not change. As a result, the bridge circuit composed of the strain resistance elements Rx21, Rx22, Rx23, and Rx24 maintains an equilibrium state, and no other-axis sensitivity is generated.

次に、Ｘ軸方向の加速度が印加され、第１の錘部２３がＸ軸方向に回動する際には、支持枠部２４に形成された第４、第５の錘部３３、３４が、第１の錘部２３と同方向に変位し、また、Ｙ軸正方向の加速度が印加され、第１の錘部２３がＹ軸正方向に回動する際には、支持枠部２４に形成された第２、第３の錘部３１，３２が、第１の錘部２３と同方向に変位するため、Ｘ、Ｙ各軸に印加される単位加速度あたりに変位する錘部の質量が、第１の錘部２３のみの場合と比較して増加する。それにより、加速度検出素子のＸ、Ｙ各軸方向の加速度感度を向上させることができる。 Next, when acceleration in the X-axis direction is applied and the first weight portion 23 rotates in the X-axis direction, the fourth and fifth weight portions 33 and 34 formed on the support frame portion 24 are When the first weight part 23 is displaced in the same direction as the first weight part 23 and the acceleration in the Y-axis positive direction is applied and the first weight part 23 rotates in the Y-axis positive direction, the support frame part 24 Since the formed second and third weight portions 31 and 32 are displaced in the same direction as the first weight portion 23, the mass of the weight portion displaced per unit acceleration applied to the X and Y axes is It increases compared to the case of only the first weight part 23. Thereby, the acceleration sensitivity of the X and Y axis directions of the acceleration detecting element can be improved.

次に、本発明の実施の形態２における３軸加速度センサの検出素子は、検出素子上の電極パッドと外部電極間を金属ワイヤーを用いたワイヤーボンディング、もしくは、電極パッドと外部電極とをＡｕ−Ａｕ接合などによる金属接合やはんだなどによる共晶接合等の接合を用いて電気的に接続される。これにより、特に、接合を用いて接続を行う際には、熱膨張などによる他材料の変形や外乱応力の影響などによって発生した応力が、梁状可撓部２５，２５′，２６，２６′および歪抵抗素子Ｒｘ２１〜Ｒｘ２４，Ｒｙ２１〜Ｒｙ２４，Ｒｚ２１〜Ｒｚ２４に伝達しやすくなる。 Next, the detection element of the triaxial acceleration sensor according to the second embodiment of the present invention is configured such that wire bonding using a metal wire is performed between the electrode pad on the detection element and the external electrode, or the electrode pad and the external electrode are connected with Au- Electrical connection is made using metal bonding such as Au bonding or eutectic bonding using solder. Thereby, particularly when connecting using bonding, stress generated by deformation of other materials due to thermal expansion or the influence of disturbance stress is caused by the beam-like flexible portions 25, 25 ', 26, 26'. And it becomes easy to transmit to the strain resistance elements Rx21 to Rx24, Ry21 to Ry24, Rz21 to Rz24.

図３（ａ）に示すように、本発明の実施の形態２における３軸加速度センサの検出素子においては、前記電気的接続に用いる電極パッド３５を薄肉部２７，２７′，２８，２８′，２９，２９′，３０，３０′および第２、第３、第４、第５の錘部３１〜３４以外の支持枠部の上面に設けることにより、電極パッド間の略中央部にはいずれかの薄肉部が設けられるようになる。それにより、図３（ｂ）に示すように、接合時および接合後の外乱・雰囲気変化によって発生する応力が、薄肉部が変位することで緩和され、それにより、梁状可撓部および歪抵抗素子に応力が伝達することを防ぐことができ、他軸感度が発生することがない。また、図３（ａ）に示す構成においては、電極パッドと外部電極との接合のみでなく、加速度検出素子を他の基板等に接着剤等を介して実装を行う際にもその効果を奏する。 As shown in FIG. 3 (a), in the detection element of the triaxial acceleration sensor according to the second embodiment of the present invention, the electrode pad 35 used for the electrical connection is made of thin portions 27, 27 ', 28, 28', 29, 29 ′, 30, 30 ′ and any of the second, third, fourth, and fifth weights 31 to 34, provided on the upper surface of the support frame, any The thin-walled portion is provided. As a result, as shown in FIG. 3 (b), the stress generated by the disturbance / atmosphere change during and after the bonding is relaxed by the displacement of the thin-walled portion, whereby the beam-shaped flexible portion and the strain resistance are reduced. It is possible to prevent stress from being transmitted to the element, and no other-axis sensitivity is generated. The configuration shown in FIG. 3A is effective not only when the electrode pad and the external electrode are joined, but also when the acceleration detection element is mounted on another substrate or the like via an adhesive or the like. .

このように、本発明の実施の形態２における３軸加速度センサの検出素子においては、Ｘ軸方向またはＹ軸方向のいずれか１つの軸方向の加速度が印加された時、加速度が印加された軸方向に、支持枠部に設けられた薄肉部が変位することで、この加速度が印加された軸に直交する他の梁状可撓部には捻れが発生せず、前記梁状可撓部と錘部との連結端部に形成した歪抵抗素子に引張歪または圧縮歪が作用しないようにでき、これにより、他軸感度を発生させることなく、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出でき、かつ、支持枠部に形成された第２、第３、第４、第５の錘部が加速度印加方向に対して、第１の錘部と同方向に変位するため、Ｘ軸およびＹ軸方向の加速度感度を向上することができるとともに、さらに、電極パッドを薄肉部および第２、第３、第４、第５の錘部以外の支持枠部の上面に設けることにより、外部電極との電気的接続時、もしくは、他の基板等への実装・接着時に発生する応力が、薄肉部が変位することで緩和され、梁状可撓部および歪抵抗素子に応力が伝達することを防ぐことができ、これにより、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出できるものである。 As described above, in the detection element of the triaxial acceleration sensor according to the second embodiment of the present invention, when the acceleration in one of the X axis direction and the Y axis direction is applied, the axis to which the acceleration is applied is applied. In the direction, the thin-walled portion provided in the support frame portion is displaced, so that the other beam-like flexible portions orthogonal to the axis to which the acceleration is applied are not twisted, and the beam-like flexible portions and Tensile strain or compressive strain can be prevented from acting on the strain resistance element formed at the connection end portion with the weight portion, so that the three axes including the X axis, the Y axis, and the Z axis can be generated without generating other axis sensitivity. The acceleration in the direction can be accurately detected, and the second, third, fourth, and fifth weights formed on the support frame are displaced in the same direction as the first weight with respect to the acceleration application direction. Therefore, the acceleration sensitivity in the X-axis and Y-axis directions can be improved, and further Mounting the electrode pad on the upper surface of the thin frame part and the support frame part other than the second, third, fourth, and fifth weight parts, when electrically connected to the external electrode, or mounted on another substrate, etc. -Stress generated at the time of adhesion is relieved by the displacement of the thin-walled portion, and it is possible to prevent stress from being transmitted to the beam-like flexible portion and the strain resistance element, whereby the X-axis, Y-axis, Z-axis It is possible to accurately detect the acceleration in the three-axis direction.

（実施の形態３）
以下、実施の形態３を用いて、本発明の特に請求項３に記載の発明についてさらに説明する。図４（ａ）−（ｃ）は本発明の実施の形態３における３軸加速度センサの検出素子の上面図である。なお、この本発明の実施の形態３においては、上記した本発明の実施の形態１の構成と同様の構成を有するものについては、同一符号を付しており、その説明は省略する。 (Embodiment 3)
In the following, the third embodiment of the present invention, particularly the invention described in claim 3, will be further described. 4A to 4C are top views of the detection element of the triaxial acceleration sensor according to Embodiment 3 of the present invention. In the third embodiment of the present invention, components having the same configurations as those of the first embodiment of the present invention are denoted by the same reference numerals, and description thereof is omitted.

図４（ａ）において、本発明の実施の形態３が上記した本発明の実施の形態１と相違する点は、支持枠部２４に設けられた薄肉部２７，２７′，２８，２８′，２９，２９′，３０，３０′に切り欠き部３６を設けた点である。 4A, the third embodiment of the present invention is different from the first embodiment of the present invention described above in that thin-walled portions 27, 27 ′, 28, 28 ′, 29, 29 ', 30, and 30' are provided with notches 36.

本発明の実施の形態３における３軸加速度センサにおいては、本発明の実施の形態１、２における３軸加速度センサと同様に他軸感度を発生させることがなく、かつ、加速度感度を向上させることができるとともに、さらに加速度感度の向上ができるものである。 In the triaxial acceleration sensor according to the third embodiment of the present invention, the other-axis sensitivity is not generated and the acceleration sensitivity is improved as in the triaxial acceleration sensor according to the first and second embodiments of the present invention. The acceleration sensitivity can be further improved.

図４（ａ）に示す本発明の実施の形態３において、Ｘ軸正方向の加速度が印加された時、本発明の実施の形態１、２における３軸加速度センサの検出素子の場合と同様にして、支持枠部２４に設けられた第３、第４の薄肉部２９，２９′，３０，３０′が第１、第２の梁状可撓部２５，２５′と同方向に変位し、第１の錘部２３における上面と、第４、第５の錘部３３，３４における上面とが同一平面となるため、第３、第４の梁状可撓部２６，２６′内で捻れが発生することがない。これにより、歪抵抗素子Ｒｚ２１，Ｒｚ２４およびＲｙ２１，Ｒｙ２４には引張または圧縮歪が作用せず抵抗値は変化しない。これにより、歪抵抗素子Ｒｚ２１，Ｒｚ２２，Ｒｚ２３，Ｒｚ２４およびＲｙ２１，Ｒｙ２２，Ｒｙ２３，Ｒｙ２４で構成されるブリッジ回路は平衡状態を維持するため、他軸感度が発生することがない。 In the third embodiment of the present invention shown in FIG. 4A, when acceleration in the X-axis positive direction is applied, the same as in the case of the detection element of the three-axis acceleration sensor in the first and second embodiments of the present invention. The third and fourth thin portions 29, 29 ', 30, 30' provided on the support frame portion 24 are displaced in the same direction as the first and second beam-like flexible portions 25, 25 ', Since the upper surface of the first weight portion 23 and the upper surfaces of the fourth and fifth weight portions 33 and 34 are coplanar, twisting occurs in the third and fourth beam-shaped flexible portions 26 and 26 '. It does not occur. Thereby, tensile resistance or compressive strain does not act on the strain resistance elements Rz21, Rz24 and Ry21, Ry24, and the resistance value does not change. As a result, the bridge circuit composed of the strain resistance elements Rz21, Rz22, Rz23, Rz24 and Ry21, Ry22, Ry23, Ry24 maintains an equilibrium state, so that no other-axis sensitivity occurs.

また、本発明の実施の形態３において、Ｙ軸正方向の加速度が印加された時も、本発明の実施の形態１，２における３軸加速度センサの検出素子の場合と同様にして、錘部２３がＹ軸の正方向へ回動しても、支持枠部２４には第１、第２の薄肉部２７，２７′，２８，２８′が設けられているため、第１、第２の梁状可撓部２５，２５′には捻れが発生することがなく、前記第１、第２の梁状可撓部２５，２５′上に形成した歪抵抗素子Ｒｘ２１，Ｒｘ２４には歪が作用しないため抵抗値は変化しない。これにより、歪抵抗素子Ｒｘ２１，Ｒｘ２２，Ｒｘ２３，Ｒｘ２４で構成されるブリッジ回路は平衡状態を維持し、他軸感度が発生することがない。 In the third embodiment of the present invention, when acceleration in the positive direction of the Y-axis is applied, the weight portion is the same as in the case of the detection element of the three-axis acceleration sensor in the first and second embodiments of the present invention. Even if 23 rotates in the positive direction of the Y-axis, the support frame portion 24 is provided with the first and second thin portions 27, 27 ', 28, 28'. The beam-like flexible portions 25 and 25 'are not twisted, and strain is applied to the strain resistance elements Rx21 and Rx24 formed on the first and second beam-like flexible portions 25 and 25'. The resistance value does not change. As a result, the bridge circuit composed of the strain resistance elements Rx21, Rx22, Rx23, and Rx24 maintains an equilibrium state, and no other-axis sensitivity is generated.

次に、Ｘ軸正方向の加速度が印加され、第１の錘部２３がＸ軸正方向に回動する際には、支持枠部２４に形成された第４、第５の錘部３３、３４が、第１の錘部２３と同方向に変位し、また、Ｙ軸正方向の加速度が印加され、第１の錘部２３がＹ軸正方向に回動する際には、支持枠部２４に形成された第２、第３の錘部３１，３２が、第１の錘部２３と同方向に変位するため、Ｘ、Ｙ各軸に印加される単位加速度あたりに変位する錘部の質量が、第１の錘部２３のみの場合と比較して増加する。それにより、加速度検出素子のＸ、Ｙ各軸方向の加速度感度を向上させることができる。 Next, when acceleration in the X-axis positive direction is applied and the first weight portion 23 rotates in the X-axis positive direction, fourth and fifth weight portions 33 formed on the support frame portion 24, 34 is displaced in the same direction as the first weight portion 23, and when the acceleration in the Y-axis positive direction is applied and the first weight portion 23 rotates in the Y-axis positive direction, the support frame portion Since the second and third weight portions 31 and 32 formed in the portion 24 are displaced in the same direction as the first weight portion 23, the weight portions that are displaced per unit acceleration applied to the X and Y axes are arranged. The mass increases as compared with the case of only the first weight portion 23. Thereby, the acceleration sensitivity of the X and Y axis directions of the acceleration detecting element can be improved.

さらに、図４（ａ）に示す本発明の実施の形態３においては、前記各薄肉部に切り欠き部３６を設け、前記各薄肉部の剛性を下げる構造となっているため、Ｘ、Ｙ各軸方向の加速度が印加された時、第２、第３、第４、第５の錘部３１〜３４の変位量を増大させることができ、これにより、加速度検出素子のＸ、Ｙ各軸方向の加速度感度をさらに向上させることができる。 Furthermore, in Embodiment 3 of the present invention shown in FIG. 4 (a), since each thin portion is provided with a notch 36, the rigidity of each thin portion is reduced. When the acceleration in the axial direction is applied, the displacement amount of the second, third, fourth, and fifth weights 31 to 34 can be increased, so that the X and Y axial directions of the acceleration detecting element can be increased. The acceleration sensitivity can be further improved.

図４（ｂ）、（ｃ）に示すように、前記切り欠き部の形状は一対の薄肉部内で同形状であれば、円形に限らず多角形のものでも構わない。また、前記各薄肉部に設ける前記切り欠き部の個数は複数でも良く、その配列方向はＸ軸方向、Ｙ軸方向どちらでも構わない。 As shown in FIGS. 4B and 4C, the shape of the notch is not limited to a circle but may be a polygon as long as it is the same shape within a pair of thin portions. Moreover, the number of the notches provided in each thin portion may be plural, and the arrangement direction may be either the X-axis direction or the Y-axis direction.

このように、本発明の実施の形態３における３軸加速度センサにおいては、本発明の実施の形態１，２における３軸加速度センサと同様に他軸感度を発生させることがないとともに、薄肉部に切り欠き部を設けることにより、支持枠部に形成された第２、第３、第４、第５の錘部の変位量を増大させることができ、Ｘ軸およびＹ軸方向の加速度感度をさらに向上することができ、これにより、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出できるものである。 As described above, the triaxial acceleration sensor according to the third embodiment of the present invention does not generate other-axis sensitivity as in the triaxial acceleration sensor according to the first and second embodiments of the present invention, and the thin portion By providing the notch, it is possible to increase the amount of displacement of the second, third, fourth, and fifth weight portions formed in the support frame, and further increase the acceleration sensitivity in the X-axis and Y-axis directions. As a result, the acceleration in the three-axis direction including the X-axis, the Y-axis, and the Z-axis can be accurately detected.

本発明に係る３軸加速度センサは、ＸＹ平面に平行に置かれた基板と、前記基板の略中央部に設けられ加速度を受けて変位する第１の錘部と、前記第１の錘部を取り囲むように配置した支持枠部と、前記第１の錘部と支持枠部とを連結しＸ軸に平行な一対の梁状可撓部と、前記第１の錘部と支持枠部とを連結しＹ軸に平行な一対の梁状可撓部と、前記梁状可撓部上でかつ前記梁状可撓部と前記第１の錘部との連結端部に形成した歪抵抗素子とを備え、前記支持枠部内に、前記Ｘ軸に平行な一対の梁状可撓部の中心軸に関して略対称で、Ｘ軸に平行な一対の薄肉部を設けることにより、加速度を受けて変位する第２、第３の錘部を形成するとともに、前記支持枠部内に、前記Ｙ軸に平行な一対の梁状可撓部の中心軸に関して対称で、Ｙ軸に平行な一対の薄肉部を設けることにより、加速度を受けて変位する第４、第５の錘部を形成したもので、Ｘ軸方向またはＹ軸方向のいずれか１つの軸方向の加速度が印加された時、この加速度が印加された軸に直交する他の梁状可撓部と、第２、第３または第４、第５の錘部が同方向に捻れるため、前記梁状可撓部と錘部との連結端部に形成した歪抵抗素子に引張歪または圧縮歪が作用しないようにでき、これにより、他軸感度を発生させることなく、Ｘ軸、Ｙ軸、Ｚ軸からなる３軸方向の加速度を正確に検出でき、かつ第１の錘部と、第２、第３または第４、第５の錘部が同方向に変位するため、加速度感度を向上させることができるという効果を有するものであり、ために、特に、自動車や航空機等の輸送機器や携帯端末等に用いてこれらの機器に働く互いに直交するＸ軸、Ｙ軸、Ｚ軸方向の加速度を検出する３軸加速度センサとして有用なものである。 A three-axis acceleration sensor according to the present invention includes a substrate placed in parallel with an XY plane, a first weight portion provided at a substantially central portion of the substrate, which is displaced by acceleration, and the first weight portion. A surrounding support frame portion, a pair of beam-like flexible portions that connect the first weight portion and the support frame portion and are parallel to the X axis, and the first weight portion and the support frame portion. A pair of beam-like flexible portions that are connected and parallel to the Y-axis, and a strain resistance element formed on the beam-like flexible portion and at a connection end portion between the beam-like flexible portion and the first weight portion; And a pair of thin-walled portions that are substantially symmetrical with respect to the central axis of the pair of beam-like flexible portions parallel to the X-axis and are parallel to the X-axis in the support frame portion, and are displaced by receiving acceleration. Second and third weight portions are formed, and the support frame portion is symmetrical with respect to the central axis of the pair of beam-like flexible portions parallel to the Y axis and is parallel to the Y axis. By providing a pair of thin-walled portions, the fourth and fifth weight portions that are displaced by the acceleration are formed, and when an acceleration in either the X-axis direction or the Y-axis direction is applied. Since the other beam-like flexible part orthogonal to the axis to which this acceleration is applied and the second, third, fourth, or fifth weight part are twisted in the same direction, the beam-like flexible part and the weight Tensile strain or compressive strain can be prevented from acting on the strain resistance element formed at the connection end portion with the portion, and thereby, the triaxial direction composed of the X axis, the Y axis, and the Z axis without generating other axis sensitivity. The acceleration can be accurately detected, and the first weight part and the second, third, fourth, and fifth weight parts are displaced in the same direction, so that the acceleration sensitivity can be improved. In particular, these are used for transportation equipment such as automobiles and airplanes, portable terminals, etc. X-axis orthogonal to each other acts on the vessel, Y-axis, is useful as a three-axis acceleration sensor for detecting acceleration in the Z-axis direction.

２１基板
２３第１の錘部
２４支持枠部
２５，２５′，２６，２６′ 梁状可撓部
Ｒｘ２１〜Ｒｘ２４，Ｒｙ２１〜Ｒｙ２４，Ｒｚ２１〜Ｒｚ２４歪抵抗素子
２７，２７′，２８，２８′，２９，２９′，３０，３０′ 薄肉部
３１〜３４第２，第３，第４，第５の錘部
３５電極パッド
３６切り欠き部 21 Substrate 23 First weight part 24 Support frame part 25, 25 ', 26, 26' Beam-like flexible part Rx21-Rx24, Ry21-Ry24, Rz21-Rz24 Strain resistance elements 27, 27 ', 28, 28', 29, 29 ', 30, 30' Thin portion 31-34 Second, third, fourth, fifth weight 35 Electrode pad 36 Notch

Claims

A substrate placed parallel to the XY plane;
A first weight portion that is provided at a substantially central portion of the substrate and receives an acceleration to be displaced;
A support frame portion arranged to surround the first weight portion;
A pair of beam-like flexible portions connecting the first weight portion and the support frame portion and parallel to the X axis;
A pair of beam-like flexible portions connecting the first weight portion and the support frame portion and parallel to the Y axis;
A strain resistance element formed on the beam-shaped flexible portion and at a connection end portion between the beam-shaped flexible portion and the first weight portion;
By providing a pair of thin portions in the support frame portion that are substantially symmetrical with respect to the central axis of the pair of beam-like flexible portions parallel to the X axis and parallel to the X axis, Forming a third weight,
In the support frame portion, by providing a pair of thin portions that are substantially symmetrical with respect to the central axis of the pair of beam-like flexible portions parallel to the Y-axis and parallel to the Y-axis, a fourth displacement that is displaced by acceleration is provided. A triaxial acceleration sensor in which a fifth weight portion is formed.

An electrode pad electrically connected to the strain resistance element is provided on the upper surface of the support frame portion at a position other than the thin portion and the second, third, fourth, and fifth weight portions. The triaxial acceleration sensor according to claim 1.

The triaxial acceleration sensor according to claim 1 or 2, wherein a cutout portion is provided in the thin portion.