阅读说明：本技术 传感器元件以及角速度传感器 (Sensor element and angular velocity sensor ) 是由 副岛宗高 高浪俊 于 2019-09-25 设计创作，主要内容包括：在传感器元件中,框架以x轴方向为长度方向。两个驱动臂从框架向y轴方向互相并列地延伸。检测臂在x轴方向上成为两个驱动臂的中央的位置处从框架向y轴方向延伸。多个激振用布线部在两个驱动臂在x轴方向上以相反的相位振动的连接关系下,连接多个激振电极以及端子。第1布线部与第1检测电极和第1检测用端子连接。第2布线部与第2检测电极和第2检测用端子连接。第1布线部的至少一部分和第2布线部的至少一部分在框架上沿框架的长度方向遍及框架的长度的1/4以上的长度而并列地延伸。(In the sensor element, the frame has a longitudinal direction in the x-axis direction. The two drive arms extend parallel to each other in the y-axis direction from the frame. The detection arm extends from the frame in the y-axis direction at a position that becomes the center of the two drive arms in the x-axis direction. The plurality of excitation wiring portions connect the plurality of excitation electrodes and the terminals in a connection relationship in which the two drive arms vibrate in opposite phases in the x-axis direction. The 1 st wiring portion is connected to the 1 st detection electrode and the 1 st detection terminal. The 2 nd wiring portion is connected to the 2 nd detection electrode and the 2 nd detection terminal. At least a part of the 1 st wiring portion and at least a part of the 2 nd wiring portion extend in parallel on the frame over a length of 1/4 or more of the length of the frame in the longitudinal direction of the frame.)

1. A sensor element having:

a piezoelectric body having a frame having a longitudinal direction in an x-axis direction of an orthogonal coordinate system xyz, two drive arms extending from the frame in a y-axis direction at positions distant from each other in the x-axis direction, and a detection arm extending from the frame in the y-axis direction between the two drive arms in the x-axis direction;

a plurality of excitation electrodes disposed on the two drive arms in an arrangement for exciting the two drive arms in an x-axis direction;

one or more 1 st detection electrodes and one or more 2 nd detection electrodes, which are located in the detection arm in an arrangement that extracts charges different in polarity from each other when the detection arm vibrates in the x-axis direction or the z-axis direction;

two excitation terminals, a 1 st detection terminal and a 2 nd detection terminal;

a plurality of excitation wiring portions connecting the plurality of excitation electrodes and the two excitation terminals in a connection relationship in which the two drive arms are bent in opposite sides to each other in the x-axis direction and vibrate in opposite phases when an alternating voltage is applied to the two excitation terminals;

a 1 st detection wiring portion connected to the 1 st detection electrode and the 1 st detection terminal; and

a 2 nd detection wiring portion connected to the 2 nd detection electrode and the 2 nd detection terminal,

at least a part of the 1 st detection wiring portion and at least a part of the 2 nd detection wiring portion extend over 1/4 or more of the length of the frame in the longitudinal direction of the frame on the frame.

2. The sensor element of claim 1,

the 1 st detection wiring portion has a 1 st wiring main body having one end connected to any one of the one or more 1 st detection electrodes and the other end connected to the other 1 st detection electrode or the 1 st detection terminal,

the 2 nd detection wiring portion has a 2 nd wiring main body having one end connected to any one of the one or more 2 nd detection electrodes and the other end connected to the other 2 nd detection electrode or the 2 nd detection terminal,

at least a portion of the 1 st wiring body and at least a portion of the 2 nd wiring body extend on the frame in a length direction of the frame.

3. The sensor element according to claim 1 or 2, wherein,

the 1 st detection wiring portion has a 1 st wiring main body having one end connected to any one of the one or more 1 st detection electrodes and the other end connected to the other 1 st detection electrode or the 1 st detection terminal,

the 2 nd detection wiring portion includes:

a 2 nd wiring main body having one end connected to any one of the one or more 2 nd detection electrodes and the other end connected to the other 2 nd detection electrode or the 2 nd detection terminal; and

one end of the second wiring is connected to any one of the 2 nd detection electrode, the 2 nd wiring main body or the 2 nd detection terminal, and the other end is an open end adjustment wiring,

at least a part of the 1 st wiring body and at least a part of the adjusting wiring extend in a longitudinal direction of the frame on the frame.

4. The sensor element according to any one of claims 1 to 3,

the piezoelectric body has two units including the frame, the two driving arms, and the detection arm, respectively,

wherein each of the two units is provided with the plurality of excitation electrodes, the one or more 1 st detection electrodes, and the one or more 2 nd detection electrodes,

the plurality of excitation wiring portions connect the plurality of excitation electrodes of the two units in a connection relationship in which the drive arms located on one side in the longitudinal direction of the frame with respect to the detection arm are bent toward the same side and the drive arms located on the other side in the longitudinal direction of the frame with respect to the detection arm are bent toward the same side, among the two units,

the two units have two of the frames having:

a 1 st portion located on one side of the detection arm in the longitudinal direction of the frame;

a 2 nd portion on the other side in the longitudinal direction of the frame than the detection arm,

the 1 st detection wiring portion is located at least the 1 st portion of the 1 st portion and the 2 nd portion of the two frames,

the 2 nd detection wiring portion is located at least at the 1 st portion out of the 1 st portion and the 2 nd portion of the two frames,

an absolute value of a difference between a 1 st length obtained by subtracting a length of the 2 nd portion of the 1 st detection wiring portion from a length of the 1 st portion of the 1 st detection wiring portion and a 2 nd length obtained by subtracting a length of the 2 nd portion of the 2 nd detection wiring portion from a length of the 1 st portion of the 2 nd detection wiring portion is 7/2 or less of a length of the 1 st portion in one frame.

5. The sensor element of claim 4,

the absolute value of the difference between the 1 st length and the 2 nd length is less than half of the length of the 1 st portion in one frame.

6. The sensor element of claim 4 or 5,

in any of the 1 st detection wiring portion and the 2 nd detection wiring portion, a portion of the two frames extending in the longitudinal direction of the frames extends only from the root side of the detection arm to the 1 st site side.

7. The sensor element of claim 4 or 5,

the 1 st detection wiring portion extends from the root side of the detection arm only to the 1 st site side, in a portion of the two frames extending in the longitudinal direction of the frames,

the 2 nd detection wiring portion extends in the longitudinal direction of the frame from the base side of the detection arm to both the 1 st portion side and the 2 nd portion side.

8. The sensor element of claim 4 or 5,

in any of the 1 st detection wiring portion and the 2 nd detection wiring portion, a portion of the two frames extending in the longitudinal direction of the frames extends from the root side of the detection arm to both the 1 st site side and the 2 nd site side.

9. A sensor element having:

the sensor element of any one of claims 1 to 8;

a drive circuit for applying an alternating voltage to the two excitation terminals; and

and a detection circuit for detecting signals from the 1 st detection terminal and the 2 nd detection terminal.

Technical Field

The present disclosure relates to a sensor element used for detecting an angular velocity and an angular velocity sensor having the sensor element.

Background

As an angular velocity sensor, a so-called piezoelectric vibration type angular velocity sensor is known (for example, patent documents 1 and 2). In this sensor, an alternating voltage is applied to a piezoelectric body to excite the piezoelectric body. When the excited piezoelectric body is rotated, a coriolis force is generated in a direction orthogonal to the excitation direction at a magnitude corresponding to the rotation speed (angular velocity), and the piezoelectric body is also vibrated by the coriolis force. By detecting an electric signal generated in accordance with the deformation of the piezoelectric body due to the coriolis force, the angular velocity of the piezoelectric body can be detected.

Patent documents 1 and 2 propose a new vibration mode for the piezoelectric body of the sensor as described above. Specifically, the piezoelectric body has: a frame having an x-axis direction of an orthogonal coordinate system xyz as a longitudinal direction; a pair of driving arms extending from the frame in parallel with each other in the y-axis direction at positions away from each other in the x-axis direction; and a detection arm extending from the frame in the y-axis direction at a position that is a center of the pair of drive arms in the x-axis direction. The pair of driving arms are excited so as to be bent in the x-axis direction toward the opposite sides to each other. Thereby, the frame generates vibration that is flexural-deformed in the y-axis direction. Further, the detection arm generates vibration that displaces in the y-axis direction. When the sensor rotates about the z-axis, the detection arm vibrates in the x-axis direction due to the coriolis force. When the sensor rotates about the x-axis, the detection arm vibrates in the z-axis direction due to the coriolis force.

Prior art documents

Patent document

Patent document 1: international publication No. 2018/021166

Patent document 2: international publication No. 2018/021167

Disclosure of Invention

A sensor element according to one embodiment of the present disclosure includes a piezoelectric body, a plurality of excitation electrodes, one or more 1 st detection electrodes, one or more 2 nd detection electrodes, two excitation terminals, a 1 st detection terminal, a 2 nd detection terminal, a plurality of excitation wiring portions, a 1 st detection wiring portion, and a 2 nd detection wiring portion. The piezoelectric body has a frame, two driving arms, and a detection arm. The frame has a longitudinal direction of an x-axis direction of an orthogonal coordinate system xyz. The two drive arms extend from the frame toward each other in the y-axis direction at positions away from each other in the x-axis direction. The detection arm extends in the x-axis direction from the frame to the y-axis direction between the two drive arms. The plurality of excitation electrodes are disposed on the two drive arms in an arrangement for exciting the two drive arms in the x-axis direction. The one or more 1 st detection electrodes and the one or more 2 nd detection electrodes are located in the detection arm in an arrangement that extracts charges different in positive and negative from each other when the detection arm vibrates in the x-axis direction or the z-axis direction. The plurality of excitation wiring portions connect the plurality of excitation electrodes and the two excitation terminals in a connection relationship in which the two drive arms are bent in the x-axis direction to opposite sides to each other and vibrate in opposite phases when an alternating voltage is applied to the two excitation terminals. The 1 st detection wiring portion is connected to the 1 st detection electrode and the 1 st detection terminal. The 2 nd detection wiring portion is connected to the 2 nd detection electrode and the 2 nd detection terminal. At least a part of the 1 st detection wiring portion and at least a part of the 2 nd detection wiring portion extend over 1/4 or more of the length of the frame in the longitudinal direction of the frame on the frame.

An angular velocity sensor according to one aspect of the present disclosure includes: the sensor element described above; a drive circuit for applying an alternating voltage to the two excitation terminals; and a detection circuit for detecting signals from the 1 st detection terminal and the 2 nd detection terminal.

Drawings

Fig. 1 is a perspective view illustrating a piezoelectric body of a sensor element according to embodiment 1.

Fig. 2 (a) is a perspective view showing a part of the sensor element of fig. 1 in an enlarged manner, and fig. 2 (b) is a sectional view taken along line IIb-IIb of fig. 2 (a).

Fig. 3 (a) and 3 (b) are schematic diagrams for explaining vibrations related to excitation of the sensor element of fig. 1.

Fig. 4 (a) and 4 (b) are schematic diagrams for explaining the vibration involved in the detection of the sensor element of fig. 1.

Fig. 5 (a) and 5 (b) are a plan view schematically showing a detection wiring of the sensor element of fig. 1 and a bottom view seen from above.

Fig. 6 (a) and 6 (b) are a plan view schematically showing a detection wiring of a sensor element according to a comparative example and a bottom view seen from above.

Fig. 7 (a) and 7 (b) are plan views schematically showing the detection wiring of the sensor element according to embodiments 2 and 3.

Fig. 8 is a plan view showing a piezoelectric body of a sensor element according to embodiment 4.

Fig. 9 (a) and 9 (b) are schematic diagrams for explaining vibrations related to excitation of the sensor element of fig. 8.

Fig. 10 (a) and 10 (b) are schematic diagrams for explaining the vibration involved in the detection of the sensor element of fig. 8.

Fig. 11 is a plan view schematically showing a detection wiring of the sensor element of fig. 8.

Fig. 12 is a bottom view schematically showing a detection wiring of the sensor element of fig. 8 in a perspective view from above.

Fig. 13 is a plan view schematically showing a wiring for detection of a sensor element according to embodiment 5.

Fig. 14 is a plan view schematically showing a wiring for detection of a sensor element according to embodiment 6.

Fig. 15 is a plan view schematically showing a wiring for detection of a sensor element according to embodiment 7.

Fig. 16 is a plan view schematically showing a wiring for detection of a sensor element according to embodiment 8.

Fig. 17 (a) is a perspective view showing a part of the sensor element according to embodiment 9 in an enlarged manner, and fig. 17 (b) is a cross-sectional view taken along line xviiib-xviiib in fig. 17 (a).

Fig. 18 (a) and 18 (b) are schematic diagrams for explaining the vibration involved in the detection of the sensor element in fig. 17 (a).

Detailed Description

In the sensor element and the angular velocity sensor according to the embodiment of the present disclosure, the configurations described in patent documents 1 and 2 can be applied in addition to the configurations and functions of the detection wiring. Therefore, the contents of patent documents 1 and 2 can be referred to by reference (Incorporation by reference).

Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. The following figures are schematic. Therefore, details are sometimes omitted, and the size ratio and the like do not always match reality. Further, the dimensional ratios of the drawings do not always match.

In the drawings, for convenience of explanation, an orthogonal coordinate system xyz is shown. The orthogonal coordinate system xyz is defined based on the shape of the sensor element (piezoelectric body). That is, the x-axis, y-axis, and z-axis are not limited to representing the electrical, mechanical, and optical axes of the crystal. In the sensor element, an arbitrary direction may be used as the upper or lower direction, but for convenience, the term "upper surface" or "lower surface" may be used with the positive side in the z-axis direction being the upper side. In the case of simply referred to as a plan view, unless otherwise specified, the view is taken in the z-axis direction.

In the same or similar structure, reference characters of different letters may be given to the drive arm 7A and the drive arm 7B, and in this case, the drive arm 7 may be simply referred to as "drive arm 7" so as not to be distinguished from each other.

Following embodiment 2, only differences from the previously described embodiments will be basically described. The points not particularly mentioned may be the same as those of the embodiments described above. In addition, in some cases, common reference numerals are used for corresponding (identical or similar) structures among the plurality of embodiments even when the shapes and the like are different.

[ embodiment 1 ]

Fig. 1 is a perspective view showing the structure of a sensor element 1 according to embodiment 1. However, in this figure, the conductive layer provided on the surface of the sensor element 1 is basically not illustrated.

The sensor element 1 constitutes, for example, a piezoelectric vibration type angular velocity sensor 51 (reference numeral is fig. 2 (b)) that detects an angular velocity around the z-axis. The sensor element 1 has a piezoelectric body 3. When the piezoelectric body 3 is rotated in a state where a voltage is applied to the piezoelectric body 3 and the piezoelectric body 3 vibrates, vibration due to coriolis force is generated in the piezoelectric body 3. Angular velocity can be detected by detecting an electrical signal (e.g., voltage or charge) generated by the vibration caused by the coriolis force. Specifically, as shown below.

(shape of piezoelectric body)

The piezoelectric body 3 is integrally formed, for example, as a whole. The piezoelectric body 3 may be a single crystal or a polycrystalline body. Further, as for the material of the piezoelectric body 3, it may be appropriately selected, for example, quartz (SiO)₂)、LiTaO₃、LiNbO₃PZT, or silicone.

In the piezoelectric body 3, an electric axis or a polarization axis (hereinafter, only the polarization axis is referred to as a "polarization axis" in some cases) is set to coincide with the x axis. The polarization axis may also be tilted within a given range (e.g., within 15 °) relative to the x-axis. When the piezoelectric body 3 is a single crystal, the mechanical axis and the optical axis may be set to appropriate directions. For example, the mechanical axis may be the y-axis direction, and the optical axis may be the z-axis direction.

The piezoelectric body 3 is fixed in thickness (z-axis direction) as a whole, for example. The piezoelectric body 3 has a line-symmetric shape with respect to a symmetry axis, not shown, which is substantially parallel to the y-axis, for example. However, the details are not necessarily line-symmetrical due to, for example, the presence of irregularities for reducing the possibility of short-circuiting of the wiring and the shape of the piezoelectric body 3 due to anisotropy in etching.

The piezoelectric body 3 includes, for example, a frame 5, two (for example, a pair, which will be described below) drive arms 7(7A and 7B) extending from the frame 5, and two (for example, a pair, which will be described below) mounting arms 11 of a detection arm 9 and a support frame 5.

The pair of driving arms 7 are excited by applying a voltage (electric field). The detection arm 9 is a portion that vibrates due to the coriolis force to generate an electric signal according to the angular velocity. The frame 5 is a portion that contributes to support of the driving arm 7 and the detection arm 9 and transmission of vibration from the driving arm 7 to the detection arm 9. The mounting arm 11 is a portion that facilitates mounting of the sensor element 1 to a mounting base (for example, a part of a housing or a circuit board) not shown.

The frame 5 is, for example, a long shape having a longitudinal direction in the x-axis direction as a whole, and is mounted on the pair of mounting arms 11. Both ends of the frame 5 become supported portions supported by the pair of mounting arms 11. The frame 5 can be deformed in a flexural manner like a beam supported at both ends in a plan view.

In the illustrated example, the frame 5 is formed to have a shape extending linearly in the x-axis direction as a whole. However, the frame 5 may have a shape other than this. For example, the frame 5 may have bent portions at both ends. In this case, the frame 5 is easily deformed by bending because the entire length of the frame 5 is increased.

Various sizes of the frame 5 may be appropriately set. For example, either the width (y-axis direction) or the thickness (z-axis direction) of the frame 5 may be larger than the other. Further, for example, since the frame 5 is preset to be deformed in a flexural manner in a plan view, the width of the frame 5 can be made relatively small. For example, the width of the frame 5 may be smaller than the width of a portion (the mounting arm 11 in the present embodiment) of the piezoelectric body 3 where the terminal 13 described later is provided. For example, the length and width of the frame 5 may be adjusted so that the natural frequency of the flexural deformation in a plan view approaches the natural frequency of the drive arm 7 in the direction excited by the voltage application and/or the natural frequency of the detection arm 9 in the direction vibrated by the coriolis force.

The length L1 of the frame 5 can be set to, for example, a length from one end to the other end of the frame 5 (a length from one to the other of the two support positions of the frame 5). In the illustrated example, the length L1 is the same as the distance (shortest distance) from the + x-side surface of the-x-side mounting arm 11 to the-x-side surface of the + x-side mounting arm 11. In the case where the frame 5 is not linear, such as when the frame 5 has a bent portion, the length L1 may be set to a length along the path of the frame 5 (more specifically, the center line thereof).

The drive arm 7 extends from the frame 5 in the y-axis direction, and its tip is a free end. Therefore, the driving arm 7 can be deformed in a flexural manner like a cantilever beam. The pair of drive arms 7 extend in parallel (for example, parallel) with each other at positions distant from each other in the x-axis direction. The pair of driving arms 7 are provided at positions that are linearly symmetrical with respect to an unillustrated symmetrical axis (see the detection arm 9) parallel to the y-axis, for example, passing through the center of the frame 5.

As will be described later (fig. 3 (a) and 3 (b)), the pair of driving arms 7 desirably causes flexural deformation (vibration) of the frame 5 in a plan view by excitation in the x-axis direction. Therefore, for example, the positions of the pair of drive arms 7 with respect to the x-axis direction of the frame 5 may be appropriately set so that the flexural deformation of the frame 5 is increased by the vibration of the pair of drive arms 7. For example, when the length 3 of the frame 5 in the x-axis direction is divided into equal parts, the pair of driving arms 7 are located in regions on both sides.

The specific shape and the like of the driving arm 7 can be set as appropriate. For example, the driving arm 7 is formed in a long rectangular parallelepiped shape. That is, the sectional shape (xz plane) is rectangular. Although not particularly shown, the drive arm 7 may be formed in a hammer shape whose width (x-axis direction) is widened at the front end side portion. The pair of driving arms 7 are formed in a shape and a size substantially symmetrical to each other. Therefore, the vibration characteristics of both are equivalent to each other. However, for example, in order to reduce unwanted vibration, the shape of the pair of driving arms 7 may be non-line-symmetric by adjusting the shape of the cross section (for example, providing a notch or the like in a rectangular shape).

The drive arm 7 is excited in the x-axis direction as described later. Therefore, if the width (x-axis direction) of the driving arm 7 is increased, the natural frequency in the excitation direction (x-axis direction) becomes high, and if the length (in another point of view, the mass) thereof is increased, the natural frequency in the excitation direction becomes low. For example, the drive arm 7 may be set to various sizes so that the natural frequency of vibration in the excitation direction of the drive arm 7 approaches a desired frequency. In this case, the desired frequency may be set to be deviated from the unwanted vibration frequency (frequency at which unwanted vibration occurs in the z-axis direction of the piezoelectric body 3) by 1kHz or more. This is because the imbalance of the frame operation at the time of excitation of the driving arm 7 can be reduced, and undesired vibration of the detection arm 9 described later can be reduced.

The detection arm 9 extends from the frame 5 in the y-axis direction, and its front end is set as a free end. Therefore, the detection arm 9 can be deformed in a flexural manner like a cantilever beam. The detection arm 9 extends between the pair of drive arms 7 in parallel (for example, parallel) with the pair of drive arms 7. The detection arm 9 is located, for example, at the center in the x-axis direction of the frame 5 and/or at the center between the pair of drive arms 7.

The specific shape and the like of the detection arm 9 can be set as appropriate. For example, the detection arm 9 may have a long rectangular parallelepiped shape. That is, the sectional shape (xz plane) is rectangular. The detection arm 9 may have a hammer shape whose width (x-axis direction) is increased at a distal end portion (see detection arms 9A and 9B in fig. 8 described later).

As will be described later, in the present embodiment, the detection arm 9 vibrates in the x-axis direction by the coriolis force. Therefore, if the width (x-axis direction) of the detection arm 9 is increased, the natural frequency in the vibration direction (x-axis direction) becomes high, and if the length (in another point of view, the mass) thereof is increased, the natural frequency in the vibration direction becomes low. For example, the detection arm 9 may be variously sized so that the natural frequency of vibration in the vibration direction of the detection arm 9 approaches the natural frequency of vibration in the excitation direction of the drive arm 7. The length of the detection arm 9 is, for example, equal to the length of the drive arm 7. However, the two may be different.

The pair of mounting arms 11 are formed in a shape having a y-axis direction as a longitudinal direction, for example. In the illustrated example, the shape of the cross section (xz section) of the mounting arm 11 is set to be constant in the longitudinal direction (y-axis direction). However, the mounting arm 11 may be formed to have a narrow width at a portion connected to the frame 5, and the shape of the cross section may be changed in the longitudinal direction. Various sizes of the mounting arm 11 may be set as appropriate.

(terminal)

At least 4 terminals 13(13A to 13D) are provided on the lower surfaces of the pair of mounting arms 11. The terminal 13 is opposed to a pad provided on the mounting base, not shown, and is bonded to the pad of the mounting base by solder or a bump containing a conductive adhesive. Thereby, the sensor element 1 and the mounting substrate are electrically connected, and the sensor element 1 (the piezoelectric body 3) is supported in a state in which the driving arm 7 and the detection arm 9 can vibrate. The 4 terminals 13 are provided at both ends of the pair of mounting arms 11, for example.

(excitation electrode and detection electrode)

Fig. 2 (a) is an enlarged perspective view of a part of the sensor element 1. Further, fig. 2 (b) is a sectional view taken along line IIb-IIb of fig. 2 (a).

The sensor element 1 includes excitation electrodes 15(15A and 15B) for applying a voltage to the drive arm 7, and detection electrodes 17(17A and 17B) for extracting a signal generated by the detection arm 9. These are formed by a conductor layer formed on the surface of the piezoelectric body 3. The material of the conductor layer is, for example, metal such as Cu or Al.

Reference numerals A, B of the excitation electrode 15 and the detection electrode 17 are given based on an orthogonal coordinate system xyz. Therefore, as will be described later, the excitation electrode 15A of one drive arm 7 and the excitation electrode 15A of the other drive arm 7 are not necessarily at the same potential. The same applies to the excitation electrode 15B. The same applies to the detection electrodes 17A and 17B in the embodiment in which a plurality of detection arms 9 are provided (in the embodiment described later).

The excitation electrodes 15A are provided on the upper surface and the lower surface (e.g., on a pair of surfaces facing both sides in the z-axis direction) of each drive arm 7. The excitation electrodes 15B are disposed on, for example, a pair of side surfaces (a pair of surfaces facing both sides in the x-axis direction) of each of the drive arms 7.

In the embodiment described later, a drive arm 7 extending from the frame 5 to the negative side in the y-axis direction may be provided. In such a driving arm 7, the reference symbol a of the excitation electrode 15 corresponds to the upper surface and the lower surface, and the reference symbol B of the excitation electrode 15 corresponds to the side surface.

The excitation electrodes 15 are formed on the respective upper, lower, left, and right surfaces of the respective drive arms 7 so as to cover most of the respective surfaces, for example. However, at least one of the excitation electrodes 15A and 15B (the excitation electrode 15A in the present embodiment) is formed smaller than each surface in the width direction so as not to be short-circuited with each other. Further, a part of the drive arm 7 on the base side and the tip side may be a non-arrangement position of the excitation electrode 15.

In each of the drive arms 7, the two excitation electrodes 15A are set to have the same potential. In each of the drive arms 7, the two excitation electrodes 15B are set to have the same potential. The excitation electrodes 15, which should be set to have the same potential as each other, are connected to each other, for example.

When a voltage is applied between the excitation electrodes 15A and 15B, for example, an electric field is generated from the upper surface toward the pair of side surfaces (both sides in the x-axis direction) and an electric field is generated from the lower surface toward the pair of side surfaces in the driving arm 7. On the other hand, the polarization axis coincides with the x-axis direction. Therefore, if the component of the electric field in the x-axis direction is focused, the direction of the electric field coincides with the direction of the polarization axis in one side portion of the x-axis direction in the drive arm 7, and the direction of the electric field is opposite to the direction of the polarization axis in the other side portion.

As a result, one side portion of the driving arm 7 in the x-axis direction contracts in the y-axis direction, and the other side portion expands in the y-axis direction. The drive arm 7 is bent toward one side in the x-axis direction like two metals. When the voltages applied to the excitation electrodes 15A and 15B are reversed, the driving arm 7 is bent in the opposite direction. According to such a principle, if an ac voltage is applied to the excitation electrodes 15A and 15B, the drive arm 7 vibrates in the x-axis direction.

Although not particularly shown, one or more grooves extending along the longitudinal direction of the drive arm 7 are provided on the upper surface and/or the lower surface of the drive arm 7 (the grooves may be formed by arranging a plurality of concave portions in the longitudinal direction of the drive arm 7), and the excitation electrodes 15A may be provided over the grooves. In this case, the excitation electrode 15A and the excitation electrode 15B are opposed to each other in the x-axis direction with the wall portion of the groove interposed therebetween, and the excitation efficiency is improved.

In the pair of drive arms 7, the excitation electrode 15A of the drive arm 7A and the excitation electrode 15B of the drive arm 7B are set to the same potential, and the excitation electrode 15B of the drive arm 7A and the excitation electrode 15A of the drive arm 7B are set to the same potential. The excitation electrodes 15 that should be set to the same potential are connected to each other, for example.

In such a connection relationship, if an alternating voltage is applied between the excitation electrodes 15A and 15B, voltages having phases opposite to each other are applied to the pair of drive arms 7. As a result, the pair of drive arms 7 vibrate as if they are flexurally deformed in directions opposite to each other in the x-axis direction.

The detection electrode 17 has the same configuration as the excitation electrode 15 in the present embodiment. That is, the detection electrodes 17A are provided on the upper surface and the lower surface (e.g., a pair of surfaces facing both sides in the z-axis direction) of the detection arm 9. The detection electrodes 17B are provided on a pair of side surfaces (e.g., a pair of surfaces facing both sides in the x-axis direction) of the detection arm 9. The two detection electrodes 17A are connected to each other, and further, the two detection electrodes 17B are connected to each other.

In the detection electrode 17, the reference symbol a corresponds to the upper surface and the lower surface, and the reference symbol B corresponds to the side surface, as in the excitation electrode 15. The above description of the width and arrangement position of the driving arm 7 of the excitation electrode 15 can be cited in the width and arrangement position of the detection arm 9 of the detection electrode 17. In addition, the detection arm 9 may have a groove formed in the upper surface and/or the lower surface.

If the detection arm 9 is deformed in the x-axis direction, a voltage is generated between the detection electrode 17A and the detection electrode 17B according to a principle opposite to the excitation of the driving arm 7. In other words, the detection electrodes 17A and 17B extract charges (potential or signal in another point of view) different in polarity (polarity) from each other from the detection arm 9. If the detection arm 9 vibrates in the z-axis direction, the voltage applied to the detection electrode 17 is detected as an alternating voltage.

(Wiring part (summary))

The sensor element 1 includes: a plurality of excitation wiring portions 19 that connect at least two of the plurality of terminals 13 (two of the 4 terminals 13 in the present embodiment) and the plurality of excitation electrodes 15 to each other; and a plurality of detection wiring portions 21 that connect at least two of the other terminals 13 (two of the other terminals in 4 terminals in the present embodiment) and the plurality of detection electrodes 17 to each other.

More specifically, a part of the excitation wiring portions 19 connects the excitation electrodes 15A and one of the 4 terminals 13 to each other. The remaining excitation wiring portions of the excitation wiring portions 19 connect the excitation electrodes 15B and the other of the 4 terminals 13 to each other. A part of the plurality of detection wiring portions 21 connects the plurality of detection electrodes 17A and another of the 4 terminals 13 to each other. The remaining detection wiring portions of the plurality of detection wiring portions 21 connect the plurality of detection electrodes 17B and the remaining one of the 4 terminals 13 to each other.

The excitation wiring portions 19 and the detection wiring portions 21 are formed by conductor layers formed on the surface of the piezoelectric body 3. The material of the conductor layer is, for example, metal such as Cu or Al. These wiring portions may be formed of the same material as that of the excitation electrode 15 and the detection electrode 17.

The plurality of excitation wiring portions 19 and the plurality of detection wiring portions 21 can be connected to each other without short-circuiting each other in such a manner that the entire portions are provided on the surface of the piezoelectric body 3 by being appropriately arranged on the upper surface, the lower surface, and/or the side surfaces of the respective portions of the piezoelectric body 3. However, the three-dimensional intersection may be formed by providing an insulating layer on the wiring portion on the piezoelectric body 3 and providing another wiring portion thereon.

The piezoelectric body 3 may be provided with one or more terminals 13 for a reference potential to which a reference potential is applied from the outside, and a reference potential wiring 20 (shown by a 2-dot chain line in fig. 2 a) connected to the terminals 13 for the reference potential. The reference potential terminal 13 may be a terminal, not shown, different from the 4 terminals 13 connected to the excitation wiring portion 19 and the detection wiring portion 21, and may be provided at an appropriate position on the lower surface of the mounting arm 11, for example.

The reference potential wiring 20 has a portion located between the excitation wiring portion 19 and the detection wiring portion 21, for example. More specifically, for example, a part of the reference potential line 20 extends in the longitudinal direction of the frame 5 (for example, in parallel) between one or more (two in the illustrated example) excitation line portions 19 and one or more (two in the illustrated example) detection line portions 21 on the upper surface and/or the lower surface of the frame 5.

By providing the reference potential wiring 20 between the excitation wiring portion 19 and the detection wiring portion 21, for example, the reference potential wiring 20 functions as a shield, and thus the influence of the drive signal flowing through the excitation wiring portion 19 on the detection signal flowing through the detection wiring portion 21 can be reduced. As a result, the detection accuracy is improved. In another aspect, the excitation wiring portion 19 and the detection wiring portion 21 can be disposed close to each other.

(drive Circuit and detection Circuit)

As shown in fig. 2 (b), the angular velocity sensor 51 includes a drive circuit 103 that applies a voltage to the excitation electrode 15, and a detection circuit 105 that detects an electric signal from the detection electrode 17.

The drive circuit 103 includes, for example, an oscillation circuit and an amplifier, and applies an ac voltage of a predetermined frequency between the excitation electrodes 15A and 15B via the two terminals 13. The frequency may be determined in advance in the angular velocity sensor 51, or may be specified from an external device or the like.

The detection circuit 105 is configured to include, for example, an amplifier and a detector circuit, detects a potential difference between the detection electrode 17A and the detection electrode 17B via the two terminals 13, and outputs an electric signal corresponding to a detection result to an external device or the like. More specifically, for example, the potential difference is detected as an ac voltage, and the detection circuit 105 outputs a signal corresponding to the amplitude of the detected ac voltage. The angular velocity may be determined based on the amplitude. The detection circuit 105 outputs a signal corresponding to a phase difference between the voltage applied to the drive circuit 103 and the detected electric signal. An orientation of the rotation may be determined based on the phase difference.

The drive circuit 103 and the detection circuit 105 constitute a control circuit 107 as a whole. The control Circuit 107 is formed of, for example, a chip IC (Integrated Circuit), and is mounted on a Circuit board on which the sensor element 1 is mounted or a mounting base body having an appropriate shape.

(operation of angular velocity sensor)

Fig. 3 (a) and 3 (b) are schematic plan views for explaining excitation of the piezoelectric body 3. In both figures, the phases of the ac voltages applied to the excitation electrodes 15 are shifted from each other by 180 °.

As described above, the driving arms 7A and 7B are excited in opposite phases by applying an alternating voltage to the excitation electrodes 15 so as to be deformed in opposite directions to each other in the x-axis direction. At this time, as shown in fig. 3a, if the pair of drive arms 7 are flexed outward in the x-axis direction (the side where the pair of drive arms 7 are separated from each other), the bending moment is transmitted to the frame 5, and the frame 5 is flexed toward the positive side in the y-axis direction. As a result, the detection arm 9 is displaced to the positive side in the y-axis direction. On the other hand, as shown in fig. 3b, if the pair of drive arms 7 are flexed toward the inner side in the x-axis direction (the side where the pair of drive arms 7 approach each other), the bending moment is transmitted to the frame 5, and the frame 5 is displaced toward the negative side in the y-axis direction. As a result, the detection arm 9 is displaced to the negative side in the y-axis direction. Therefore, the pair of driving arms 7 are excited, and the detection arm 9 vibrates in the y-axis direction.

Fig. 4 (a) and 4 (b) are schematic perspective views for explaining the vibration of the detection arm 9 caused by the coriolis force. Fig. 4 (a) and 4 (b) correspond to the states of fig. 3 (a) and 3 (b). In the figure, the driving arm 7 and the frame 5 are not shown in their modified forms.

As described with reference to fig. 3 (a) and 3 (b), the piezoelectric body 3 is vibrating. In this state, if the sensor element 1 rotates about the z-axis, the detection arm 9 vibrates (displaces) in the y-axis direction, and therefore vibrates (deforms) in a direction (x-axis direction) orthogonal to the rotation axis (z-axis) and the vibration direction (y-axis) due to the coriolis force. The signal (e.g., voltage) generated by the deformation is extracted by the detection electrode 17 as described above. The coriolis force (further, the voltage of the detected signal) increases as the angular velocity increases. Thereby, the angular velocity can be detected.

(Wiring part for detection)

Fig. 5 (a) is a plan view schematically showing the detection line segment 21 (a view showing the + z side surface). Fig. 5 (b) is a bottom view schematically showing the detection wiring portion 21 (a view showing a surface on the-z side). However, (b) of fig. 5 is a perspective view of the sensor element 1 from above (+ z side), showing the lower surface of the sensor element 1.

In these drawings, the piezoelectric body 3, the detection electrode 17, the detection wiring portion 21, and the terminal 13 are schematically shown. As described above, the terminals 13 connected to the detection electrodes 17, the detection wiring portions 21, and the detection wiring portions 21 are divided into 2 groups from the viewpoint of potential. The combinations of the potentials different from each other are hatched differently from each other.

In fig. 5 (a), an example of the position of at least a part of the reference potential wiring 20 in the case where the wiring is provided is also shown as a 2-dot chain line. The excitation wiring portion 19, which is not shown here, may be provided on the opposite side of the reference potential wiring 20 from the detection wiring portion 21. The same applies to other drawings corresponding to fig. 5 (a) in other embodiments described later.

A detection wiring portion related to one potential among the plurality of detection wiring portions 21 is referred to as a "1 st wiring portion 21P". The detection wiring portion related to another potential among the plurality of detection wiring portions 21 is referred to as a "2 nd wiring portion 21N". The 1 st wiring portion 21P includes, for example, a detection wiring portion 21 for connecting the detection electrode 17 and the terminal 13, and a detection wiring portion 21 for connecting the detection electrodes 17 to each other. In other words, the 1 st wiring portion 21P includes a plurality of sites divided by the detection electrodes 17. The same applies to the 2 nd wiring portion 21N.

In addition, a portion of the frame 5 on one side (the (-x side) in the longitudinal direction of the frame 5 with respect to the detection arm 9 is referred to as a "1 st portion 5 a". A portion of the frame 5 on the other side (+ x side) in the longitudinal direction of the frame 5 than the detection arm 9 is referred to as a "2 nd portion 5 b". The 1 st portion 5a and the 2 nd portion 5b are substantially line-symmetric with respect to the detection arm 9.

As has been described, the detection electrodes 17A are connected to each other, and the detection electrodes 17B are connected to each other. In the illustrated example, the detection electrodes 17A are connected to each other through a portion of the 2 nd wiring portion 21N located at the tip of the detection arm 9. The detection electrodes 17B are connected to each other by a portion of the 1 st wiring portion 21P located around the root portion of the detection arm 9 of the frame 5. The positional relationship (the tip side or the root side) of the detection wiring portion 21 connecting the detection electrodes 17 to each other with respect to the detection arm 9 may be reversed from the illustrated example.

The 1 st wiring portion 21P has a portion extending along the frame 5 from the vicinity of the root of the detection arm 9 to one side (-x side) in the longitudinal direction of the frame 5. Similarly, the 2 nd wiring portion 21N has a portion extending along the frame 5 from the vicinity of the root of the detection arm 9 to one side (x side) in the longitudinal direction of the frame 5. That is, the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend toward the same side with respect to the detection arm 9 in the frame 5. The same side may be the + x side, opposite to the illustrated example. In another aspect, at least a part of the two wiring portions extends in parallel in the longitudinal direction of the frame 5 on the frame 5. In the illustrated example, the length of the parallel extension is a length of 1/2 slightly shorter than the length of the frame 5, in other words, 1/4 or more of the length of the frame 5. The 1 st wiring portion 21P and the 2 nd wiring portion 21N extend up to the end of the frame 5, and then extend on the mounting arm 11, and are connected to the terminals 13A and 13C.

The shape, width, and the like of the 1 st portion 5a (or the 2 nd portion 5 b. the same applies hereinafter) of the 1 st wiring portion 21P and the 2 nd wiring portion 21N can be appropriately set. For example, the 1 st wiring portion 21P and the 2 nd wiring portion 21N linearly extend over the entire length of the 1 st portion 5a or over 8 th portions with a constant width. Further, the width in the 1 st site 5a is the same in, for example, the 1 st wiring portion 21P and the 2 nd wiring portion 21N. However, the 1 st wiring portion 21P and the 2 nd wiring portion 21N may be bent in the process of extending in the longitudinal direction thereof in the 1 st portion 5a, and the widths may be changed or may be different from each other.

As described above, in the present embodiment, the sensor element 1 includes the piezoelectric body 3, the plurality of excitation electrodes 15, the plurality of detection electrodes 17, the plurality of terminals 13, the plurality of excitation wiring portions 19, and the 1 st and 2 nd detection wiring portions (the 1 st wiring portion 21P and the 2 nd wiring portion 21N). The piezoelectric body 3 has a frame 5, a pair of driving arms 7, and a detection arm 9. The frame 5 has the x-axis direction of the orthogonal coordinate system xyz as the longitudinal direction. The pair of drive arms 7 extend from the frame 5 in parallel with each other in the y-axis direction at positions distant from each other in the x-axis direction. The detection arm 9 extends from the frame 5 in the y-axis direction at a position that becomes the center of the pair of drive arms 7 in the x-axis direction. The excitation electrodes 15 are disposed on the pair of drive arms 7 so as to excite the pair of drive arms 7 in the x-axis direction. The detection electrodes 17A and 17B are located in the detection arm 9 in an arrangement that extracts mutually different positive and negative charges when the detection arm 9 vibrates in the x-axis direction or the z-axis direction (in the present embodiment, the x-axis direction). The excitation wiring portions 19 connect the excitation electrodes 15 and the two terminals 13B and 13D in a connection relationship in which the pair of drive arms 7 are bent in the x-axis direction to opposite sides to each other and vibrate in opposite phases when an ac voltage is applied to the two excitation terminals (13B and 13D in fig. 5 (B)). The 1 st wiring portion 21P is connected to one or more 1 st detection electrodes (in the illustrated example, the detection electrodes 17B) and 1 st detection terminals (in the illustrated example, the terminals 13A). The 2 nd wiring portion 21N is connected to one or more 2 nd detection electrodes (detection electrodes 17A in the illustrated example) and a 2 nd detection terminal (terminal 13C in the illustrated example). At least a part of the 1 st wiring portion 21P and at least a part of the 2 nd wiring portion 21N extend in parallel on the frame 5 (on the 1 st site 5a) over a length of 1/4 or more of the length of the frame 5 in the longitudinal direction of the frame 5.

Therefore, for example, the detection accuracy can be improved. Specifically, as shown below.

Fig. 6 (a) and 6 (b) are views corresponding to fig. 5 (a) and 5 (b) schematically showing the detection wiring portion 21 of the sensor element 101 according to the comparative example.

In the sensor element 101, unlike the embodiment, the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in opposite directions to each other with respect to the detection arm 9 in the frame 5. With this difference, the terminal 13 connected to the 2 nd wiring portion 21N is also different from the embodiment. Although not particularly shown, the arrangement of the excitation wiring portion 19 and the terminals 13 connected to the excitation wiring portion 19 are also different from those of the embodiment.

In the sensor element 101, the frame 5 is deformed in the y-axis direction, as in the sensor element 1 of the embodiment. Along with this deflection deformation, an electric charge is generated in the upper surface of the frame 5. The positive and negative and/or magnitude of the charge are different from each other in the 1 st site 5a and the 2 nd site 5 b. For example, when the sensor element 1 is configured such that the pair of drive arms 7 are driven in line symmetry in the x-axis direction as in the present embodiment, the positive and negative charges generated at the 1 st site 5a and the 2 nd site 5b are substantially opposite to each other, and have substantially equal magnitudes (absolute values) in many cases. In the following description, this case is also taken as an example.

The electric charge generated at the 1 st site 5a is applied to the 1 st wiring portion 21P located at the 1 st site 5 a. The charge generated at the 2 nd site 5b is applied to the 2 nd wiring portion 21N located at the 2 nd site 5 b. Therefore, a voltage is applied from the frame 5 to the 1 st wiring portion 21P and the 2 nd wiring portion 21N.

As a result, the voltage between the two terminals 13(13A and 13B in fig. 6B) connected to the 1 st wiring portion 21P and the 2 nd wiring portion 21N is a voltage obtained by superimposing the voltage applied from the frame 5 to the wiring portions on the voltage detected by the detection electrode 17. Thus, the voltage between the two terminals 13 is greater than or less than the voltage that should be detected. That is, noise is mixed in the detection signal from the detection electrode 17, and the detection accuracy of the sensor element 1 is lowered.

On the other hand, in the sensor element 1 according to the embodiment, the 1 st wiring portion 21P and the 2 nd wiring portion 21N are both located at the 1 st site 5a and are not located at the 2 nd site 5 b. Therefore, the positive and negative charges applied from the frame 5 to the two wiring portions are the same. Then, the potentials of the two wiring portions rise or fall together by the electric charges. That is, the voltage applied to the two wiring portions is either not generated or is reduced as compared with the comparative example by the electric charge generated in the frame 5. As a result, noise mixed in the detection signal from the detection electrode 17 is reduced, and the detection accuracy of the sensor element 1 is improved.

A part of the structure and effects of embodiment 1 will be more easily understood in comparison with embodiment 2 than in comparison with comparative example. Therefore, the configuration and effects of embodiment 1 will be supplemented in the description of embodiment 2 to be described later.

In the embodiment, the 1 st wiring portion 21P and the 2 nd wiring portion 21N are located only on the upper surface out of the upper surface and the lower surface of the frame 5. However, the two wiring portions may be located on the lower surface of the frame 5. In addition, the positive and negative of the potential generated on the upper surface and the lower surface are often the same. Therefore, at least a part of the two wiring portions may be disposed separately on the upper surface and the lower surface. The same applies to the embodiments described later.

At the periphery of the root portion of the detection arm 9, the detection-use wiring portions 21 are staggered, whereby the 1 st wiring portion 21P and the 2 nd wiring portion 21N may undesirably run in parallel along the longitudinal direction of the frame 5. However, it is considered that such parallelism only around the root of the detection arm 9 does not extend over 1/4 or more of the length of the frame 5.

In the above embodiment 1, the detection electrode 17B is an example of the 1 st (or 2 nd) detection electrode. The detection electrode 17A is an example of the 2 nd (or 1 st) detection electrode. The 1 st wiring portion 21P is an example of the 1 st (or 2 nd) detection wiring portion. The 2 nd wiring portion 21N is an example of the 2 nd (or 1 st) detection wiring portion. The terminal 13A is an example of the 1 st (or 2 nd) detection terminal. The terminal 13C is an example of a 2 nd (or 1 st) detection terminal. The terminals 13B and 13D are examples of excitation terminals.

[ 2 nd embodiment ]

Fig. 7 (a) is a view (plan view) corresponding to fig. 5 (a) schematically showing the detection wiring portion 21 of the sensor element 201 according to embodiment 2. The bottom view of the sensor element 201 is the same as that of fig. 6 (b) according to the comparative example.

The sensor element 201 is the sensor element 101 according to the comparative example, in which the configuration of the 2 nd wiring portion 21N is changed. Specifically, the 2 nd wiring portion 21N is configured by adding the adjustment wiring 21b to the wiring main body 21a of the sensor element 101 corresponding to the 2 nd wiring portion 21N.

The wiring main body 21a is a portion in which one end of the 2 nd wiring portion 21N (or the 1 st wiring portion 21P) is connected to the detection electrode 17 and the other end is connected to another detection electrode 17 or the terminal 13. That is, the wiring main body 21a constitutes a transmission path of the detection signal from the detection electrode 17 to the detection circuit 105. On the other hand, the adjustment wiring 21b is a portion in which one end of the 2 nd wiring portion 21N (or the 1 st wiring portion 21P) is directly or indirectly connected to the detection electrode 17 and the other end is open. That is, the adjustment wiring 21b does not directly constitute a transmission path of the detection signal from the detection electrode 17 to the detection circuit 105.

As will be understood from various embodiments described later, a plurality of wiring bodies 21a may be provided in each of the 1 st wiring portion 21P and the 2 nd wiring portion 21N, and a plurality of adjustment wirings 21b may be provided. A part of the plurality of wiring bodies 21a may be shared with each other. One end of the adjustment wire 21b may be directly connected to the detection electrode 17, or may be connected to the detection electrode 17 via the wire body 21a or the terminal 13. Depending on the manner of bending of the wiring, the wiring body 21a extends from the detection electrode 17 to the terminal 13 even if the wiring body 21a appears to extend from the middle of the adjustment wiring 21 b. The other end of the adjustment wire 21b is an open end, in other words, the other end is not connected to the terminal 13 or the like.

In the same manner as in the comparative example, the wiring main body 21a of the 2 nd wiring portion 21N extends in the longitudinal direction of the frame 5 from the periphery of the root portion of the detection arm 9 in the direction opposite to the 1 st wiring portion 21P (the wiring main body 21a thereof). On the other hand, the adjusting wires 21b of the 2 nd wiring portion 21N extend in the longitudinal direction of the frame 5 from the periphery of the root portion of the detection arm 9 in the same direction as the 1 st wiring portion 21P. In other words, the main wiring body 21a of the 1 st wiring portion 21P and the trimming wiring 21b of the 2 nd wiring portion 21N are both located at the 1 st site 5 a.

The shape, size, and the like of the adjustment wire 21b can be appropriately set. For example, the adjustment wires 21b extend linearly with a constant width over the entire length of the 1 st portion 5a or over 8 th portions. The width of the 1 st portion 5a of the adjustment wire 21b is, for example, the same as the width of the wire main body 21a of the 1 st wire portion 21P and/or the 2 nd wire portion 21N. However, the adjusting wire 21b may be smaller than 8 times the entire length of the 1 st portion 5a, may be bent while extending in the longitudinal direction in the 1 st portion 5a, may have a variable width, or may have a width different from the width of the 1 st wire portion 21P and/or the 2 nd wire portion 21N. Further, the adjustment wire 21b may extend so as to be folded back in the frame 5, the mounting arm 11, or the like.

In contrast to the illustrated example, the 1 st wiring portion 21P may have the trimming line 21b at the 2 nd site 5b instead of the 2 nd wiring portion 21N at the 1 st site 5 a.

With the above configuration, the effect of reducing the influence of the electric charge generated in the frame 5 can be obtained. Specifically, in the 2 nd wiring portion 21N of the present embodiment, the charge applied to the wiring main body 21a located at the 2 nd site 5b and the charge applied to the adjustment wiring 21b located at the 1 st site 5a have opposite signs. As a result, at least a part of the two charges is cancelled in the 2 nd wiring portion 21N. For example, if it is assumed that all the electric charges are cancelled in the 2 nd wiring portion 21N, a voltage between the 1 st wiring portion 21P and the 2 nd wiring portion 21N is generated only by the electric charges given to the 1 st wiring portion 21P. On the other hand, in the comparative example, as described above, voltages are applied to the 1 st wiring portion 21P and the 2 nd wiring portion 21N due to the charges having different positive and negative polarities from each other. Therefore, in the present embodiment, the voltage (noise) applied to the 1 st wiring portion 21P and the 2 nd wiring portion 21N due to the flexural deformation of the frame 5 is reduced as compared with the comparative example.

The above-described effects are further examined on the assumption that the description is simple. As shown in fig. 6 (a), La represents the length of each of the 1 st portion 5a and the 2 nd portion 5b in the longitudinal direction. Similarly, La is the length of the 1 st wiring portion 21P and the 2 nd wiring portion 21N extending at the 1 st site 5a or the 2 nd site 5 b. The electric charges generated in the 1 st site 5a and the 2 nd site 5b have opposite polarities and the same magnitude. When the length of the detection line portion 21 extending in the x-axis direction is the same in the 1 st site 5a or the 2 nd site 5b, the same magnitude (absolute value) of electric charge is applied. In the following various descriptions, for convenience sake, accuracy is sometimes neglected and the description is made under this assumption.

If the assumption is made as described above, the magnitude of the difference in the electric charges generated between the 1 st wiring portion 21P and the 2 nd wiring portion 21N can be determined by comparing the lengths of the 1 st portion 5a and the 2 nd portion 5b of the two wiring portions, and can be considered instead of the length La. For example, a 1 st length LP obtained by subtracting the length of the 2 nd portion 5b from the length of the 1 st portion 5a for the 1 st wiring portion 21P, and a 2 nd length LN obtained by subtracting the length of the 2 nd portion 5b from the length of the 1 st portion 5a for the 2 nd wiring portion 21N may be considered. As long as the difference between LP and LN is 0, there is no difference in the electric charges applied to the 1 st wiring portion 21P and the 2 nd wiring portion 21N, and no voltage (noise) is generated therebetween. If the absolute value of the difference between LP and LN is large, the voltage generated between the two wiring portions becomes large.

For example, in the comparative example (fig. 6 (a)), the length LP obtained by subtracting the length (0) at the 2 nd site 5b from the length (La) at the 1 st site 5a in the 1 st wiring portion 21P is La. The 2 nd wiring portion 21N has a length LP obtained by subtracting the length (La) at the 2 nd portion 5b from the length (0) at the 1 st portion 5a, and is-La. Therefore, the difference between the lengths LP and LN is (La- (-La)) 2 La.

In embodiment 1 (fig. 5 (a)), for example, the length LP of the 1 st wiring portion 21P obtained by subtracting the length (0) of the 2 nd portion 5b from the length (La) of the 1 st portion 5a is La. The length LP of the 2 nd wiring portion 21N obtained by subtracting the length (0) of the 2 nd portion 5b from the length (La) of the 1 st portion 5a is La. Therefore, the difference between the lengths LP and LN becomes (La — La) 0.

In embodiment 2 (fig. 7 (a)), for example, the length LP of the 1 st wiring portion 21P obtained by subtracting the length (0) of the 2 nd portion 5b from the length (La) of the 1 st portion 5a is La. The length LP of the 2 nd portion 5b (the length La of the adjustment wire 21 b) subtracted from the length of the 1 st portion 5a (the length La of the wire body 21a) is 0 for the 2 nd wire portion 21N. Therefore, the difference between the lengths LP and LN is La-0 ═ La.

Therefore, under the assumption described above, in embodiment 1, all voltages (noise) applied from the frame 5 to the 1 st wiring portion 21P and the 2 nd wiring portion 21N are cancelled. In addition, in embodiment 2, the voltage applied from the frame 5 to the 1 st wiring portion 21P and the 2 nd wiring portion 21N can be halved compared to the comparative example.

As described above, in the present embodiment, at least a part of the 1 st detection wiring portion (the 1 st wiring portion 21P) and at least a part of the 2 nd detection wiring portion (the 2 nd wiring portion 21N) also extend in parallel on the frame 5 along the longitudinal direction of the frame 5 over 1/4 or more of the length of the frame 5. Therefore, the same effects as those of embodiment 1 can be achieved. For example, it is possible to reduce the difference between the electric charge applied from the frame 5 to the 1 st wiring portion 21P and the electric charge applied from the frame 5 to the 2 nd wiring portion 21N, and to reduce noise caused by flexural deformation of the frame 5.

In the present embodiment, the 1 st detection wiring portion (the 1 st wiring portion 21P) includes the 1 st wiring main body (the wiring main body 21 a). One end of the wiring main body 21a of the 1 st wiring portion 21P is connected to the 1 st detection electrode (detection electrode 17B), and the other end is connected to the other 1 st detection electrode (other detection electrode 17B) or the 1 st detection terminal (see the terminal 13A in fig. 6B). The 2 nd detection wiring portion (the 2 nd wiring portion 21N) has a 2 nd wiring main body (the wiring main body 21a) and an adjustment wiring 21 b. One end of the wiring main body 21a of the 2 nd wiring portion 21N is connected to the 2 nd detection electrode (detection electrode 17A), and the other end is connected to the other 2 nd detection electrode (the other detection electrode 17A) or the 2 nd detection terminal (see the terminal 13B in fig. 6B). One end of the adjustment wire 21B is connected to the detection electrode 17A, the main wiring body 21a of the 2 nd wiring portion 21N, or the terminal 13B, and the other end is open. At least a part of the wiring main body 21a of the 1 st wiring portion 21P and at least a part of the adjusting wiring 21b of the 2 nd wiring portion 21N extend in parallel in the longitudinal direction of the frame 5 on the frame 5.

Therefore, as can be understood from a comparison of, for example, a comparative example (fig. 6 (a)), embodiment 1 (fig. 5 (a)), and the present embodiment (fig. 7 (a)), the present embodiment has a reduced need to change the position of the wiring main body 21a and/or the connection relationship between the various electrodes and the plurality of terminals 13, compared to the comparative example. Therefore, for example, noise caused by flexural deformation of the frame 5 can be reduced by a simple method of adding the adjustment wiring 21b without significantly changing the initial design. Further, for example, since the length of the adjustment wiring 21b (in another point of view, the position of the open end) is arbitrary, the length of the adjustment wiring 21b can be adjusted based on the measured value of the noise caused by the flexural deformation of the frame 5, and the effect of noise reduction can be improved.

In the present embodiment, the portion of the 1 st detection wiring portion (the 1 st wiring portion 21P) extending in the longitudinal direction of the frame 5 on the frame 5 extends from the root side of the detection arm 9 only toward the 1 st site 5a side. The 2 nd detection wiring portion (2 nd wiring portion 21N) extends from the base side of the detection arm 9 toward the 1 st portion 5a and the 2 nd portion 5b, respectively, in a portion of the frame 5 extending in the longitudinal direction of the frame 5.

In this case, for example, the electric charges generated in both the 1 st site 5a and the 2 nd site 5b can be guided to the outside through the detection wiring portion 21. Therefore, the possibility that the electric charges of the 1 st site 5a and the 2 nd site 5b form an undesired electric field around the detection arm 9 or the drive arm 7 can be reduced. Further, for example, compared to the mode in which the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend only to the 1 st site 5a side (embodiment 1), it is easier to make the area of the detection wiring portion 21 located at the 1 st site 5a and the area of the detection wiring portion 21 located at the 2 nd site 5b close to each other. As a result, for example, the influence of the detection wiring portion 21 on the rigidity of the frame 5 can be easily made to approach the 1 st portion 5a and the 2 nd portion 5 b.

(supplement to the description of embodiment 1)

In embodiment 1, unlike embodiment 2, at least a part of the 1 st wiring body (the wiring body 21a of the 1 st wiring portion 21P) and at least a part of the 2 nd wiring body (the wiring body 21a of the 2 nd wiring portion 21N) extend in parallel in the longitudinal direction of the frame 5 on the frame 5.

In this case, for example, since noise caused by flexural deformation of the frame 5 is reduced by the structure of the wiring main body 21a itself, the area of the detection wiring portion 21 on the frame 5 is easily reduced.

In embodiment 1, the 1 st detection line segment (the 1 st line segment 21P) is located at least the 1 st site 5a of the 1 st site 5a and the 2 nd site 5 b. The 2 nd detection line portion (the 2 nd line portion 21N) is located at least at the 1 st site 5a of the 1 st site 5a and the 2 nd site 5 b. The difference between the 1 st length (LP ═ La-0) obtained by subtracting the length (0) in the 2 nd portion 5b of the 1 st wiring portion 21P from the length (La) in the 1 st portion 5a of the 1 st wiring portion 21P and the 2 nd length (LN ═ La-0) obtained by subtracting the length (0) in the 2 nd portion 5b of the 2 nd wiring portion 21N from the length (La) in the 1 st portion 5a of the 2 nd wiring portion 21N is equal to or less than half (0) of the length La of the 1 st portion 5 a.

Therefore, as described above, embodiment 1 can reduce noise caused by flexural deformation of the frame 5, not only with respect to the comparative example but also with respect to embodiment 2. The length of the detection line segment 21 may be, for example, a length on the center line of the detection line segment 21, or may include a length extending in the y-axis direction as well as a length extending in the x-axis direction. As described above, since the detection line portions 21 are staggered around the root portions of the detection arms 9, the difference between the 1 st length LP and the 2 nd length LN may be undesirably reduced in the comparative example (fig. 6 (a)). However, if the reduction is caused by such an interleaving, the difference is not half or less of the length La.

In embodiment 1, in any of the 1 st detection wiring portion (the 1 st wiring portion 21P) and the 2 nd detection wiring portion (the 2 nd wiring portion 21N), a portion extending in the longitudinal direction of the frame 5 on the frame 5 extends only from the root portion side of the detection arm 9 to the 1 st portion 5a side.

In this case, for example, the number of the adjustment wires 21b can be reduced or the adjustment wires 21b can be eliminated. That is, with a simplified configuration, the difference between the 1 st length LP and the 2 nd length LN can be set to be equal to or less than half the length La.

In embodiment 2 and embodiment 3 described later, unlike embodiment 1, the terminal 13B is an example of a 2 nd (or 1 st) detection terminal (see fig. 6 (B)). The terminals 13C and 13D are examples of excitation terminals.

[ embodiment 3 ]

Fig. 7 (b) is a view (plan view) corresponding to fig. 5 (a) schematically showing the detection wiring portion 21 of the sensor element 301 according to embodiment 3. The bottom view of the sensor element 301 is the same as that of fig. 6 (b) in the comparative example.

In embodiment 2, the adjustment wire 21b is provided only in the 2 nd wiring portion 21N out of the 1 st wiring portion 21P and the 2 nd wiring portion 21N. In contrast, in the present embodiment, the adjustment wire 21b is also provided in the 1 st wiring portion 21P. In the present embodiment, the difference (0-0) between the 1 st length (LP-La-0) obtained by subtracting the length of the 2 nd portion 5b of the 1 st wiring portion 21P (the length La of the adjustment wiring 21 b) from the length of the 1 st portion 5a of the 1 st wiring portion 21P (the length La of the wiring body 21a) and the 2 nd length (LN-La-0) obtained by subtracting the length of the 2 nd portion 5b of the 2 nd wiring portion 21N (the length La of the adjustment wiring 21a) from the length of the 1 st portion 5a of the 2 nd wiring portion 21N (the length La of the wiring body 21a) is equal to or less than half of the length La of the 1 st portion 5 a.

As described above, in the present embodiment, as in the 1 st and 2 nd embodiments, at least a part of the 1 st detection wiring portion (the 1 st wiring portion 21P) and at least a part of the 2 nd detection wiring portion (the 2 nd wiring portion 21N) extend in parallel on the frame 5 over 1/4 or more of the length of the frame 5 in the longitudinal direction of the frame 5. Therefore, the same effects as those of the other embodiments can be achieved. For example, it is possible to reduce the difference between the electric charge applied from the frame 5 to the 1 st wiring portion 21P and the electric charge applied from the frame 5 to the 2 nd wiring portion 21N, and to reduce noise caused by flexural deformation of the frame 5.

In the present embodiment, similarly to embodiment 2, at least a part of the wiring main body 21a of one of the 1 st wiring portion 21P and the 2 nd wiring portion 21N and at least a part of the adjusting wiring 21b of the other of the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in parallel in the longitudinal direction of the frame 5 on the frame 5. Therefore, for example, as in embodiment 2, noise caused by flexural deformation of the frame 5 can be reduced by a simple method of adding the adjustment wiring 21b to the comparative example (initial design from another point of view). On the other hand, in the present embodiment, as in embodiment 1, the difference between the 1 st length LP and the 2 nd length LN is equal to or less than half the length La of the 1 st portion 5 a. Therefore, compared to embodiment 2, noise caused by flexural deformation of the frame 5 is easily reduced.

In another aspect, in any of the 1 st detection wiring portion (the 1 st wiring portion 21P) and the 2 nd detection wiring portion (the 2 nd wiring portion 21N), the portion extending in the longitudinal direction of the frame 5 on the frame 5 extends from the root side of the detection arm 9 toward both the 1 st portion 5a side and the 2 nd portion 5b side.

In this case, for example, as in embodiment 1, the difference between the 1 st length LP and the 2 nd length LN can be set to be equal to or less than half the length La. On the other hand, as in embodiment 2, for example, the electric charges generated in both the 1 st site 5a and the 2 nd site 5b can be guided to the outside through the detection wiring portion 21. Further, for example, the area of the detection line segment 21 located at the 1 st site 5a and the area of the detection line segment 21 located at the 2 nd site 5b can be easily approximated to each other.

[ 4 th embodiment ]

Fig. 8 is a plan view showing the structure of a sensor element 401 according to embodiment 4. However, in this figure, the conductive layer provided on the surface of the sensor element 401 is basically not illustrated.

(Structure of sensor element)

First, the piezoelectric body 403 of the sensor element 401 has a shape in which two piezoelectric bodies 3 according to embodiment 1 are combined. That is, the piezoelectric body 403 includes two units 404(404A and 404B), and each unit 404 includes a frame 5(5A or 5B), at least one pair (two pairs in the present embodiment) of drive arms 7(7C to 7J) and detection arms 9(9A or 9B) extending from the frame 5 in parallel with each other in the y-axis direction.

The two units 404 are disposed so that the sides opposite to the direction in which the drive arm 7 and the detection arm 9 extend are opposed to each other. The distance between the two units 404 may be set appropriately, for example, so that the frames 5A and 5B do not contact each other. The two units 404 have substantially the same shape and size (symmetrical shape and size with respect to an unillustrated symmetry axis parallel to the x-axis), for example.

The piezoelectric body 3 of embodiment 1 includes a pair of mounting arms 1 as a portion where the support frame 5 and the terminals 13 are provided. In contrast, in the piezoelectric body 403, the mounting portion 411 corresponding to the mounting arm 11 includes, in a plan view, the inner frame 23 supporting the frame 5, the projection 25 projecting outward from the inner frame 23, and the outer frame 27 connected to the tip of the projection 25, and the plurality of terminals 13 are provided on the lower surface of the outer frame 27.

The illustrated mounting portion 411 is merely an example of a mounting portion that supports two frames 5. The mounting portion can be of various shapes. For example, the outer frame 27 may be a plurality of legs extending while being bent in an appropriate direction, instead of the frame shape. The number of the projections 25 may be only one instead of two. Instead of providing the outer frame 27 and the projections 25, a plurality of terminals 13 may be provided in the inner frame 23. Instead of the mounting portions 411, the two frames 5 may be supported by the same structure as the pair of mounting arms 11 of embodiment 1.

In the illustrated example, the number of the plurality of terminals 13 is 6. Of these, 4 are connected to excitation electrodes 15 divided into 2 groups from the viewpoint of potential and detection electrodes 17 divided into 2 groups from the viewpoint of potential, as in embodiment 1. The other two terminals are, for example, terminals to which a reference potential is applied as mentioned in embodiment 1, and are connected to the reference potential wiring 20. The 6 terminals 13 can be arranged at appropriate positions of the outer frame 27. The reference potential wiring 20 and the terminal 13 for reference potential may not be provided.

The piezoelectric body 3 of embodiment 1 has a pair of drive arms 7 with respect to one frame 5, and the unit 404 of the piezoelectric body 403 has two pairs of drive arms 7 with respect to one frame 5. As described later (fig. 10 (a) and 10 (b)), the two adjacent drive arms 7 are bent together in the same direction in the x-axis direction by applying voltages in the same phase (two of 7C and 7D, two of 7E and 7F, two of 7G and 7H, and two of 7I and 7J). Therefore, the adjacent two drive arms 7 can be regarded as corresponding to one drive arm 7 of embodiment 1.

By thus dividing the drive arm 7 of embodiment 1 into two parts, for example, even if the length of the drive arm 7 is shortened, the mass of the entire drive arm 7 can be ensured, and further, both downsizing and improvement in detection sensitivity can be achieved. The driving arms 7 may also be provided in more than two pairs with respect to one frame. The adjacent two drive arms 7 are, for example, substantially identical in shape and size to each other. However, they may be different from each other. The piezoelectric body 403 is, for example, substantially line-symmetrical with respect to a symmetry axis (detection arm 9) not shown, and the shape and arrangement of the plurality of drive arms 7 are also substantially line-symmetrical.

The excitation electrode 15 and the detection electrode 17 in each section 404 of the sensor element 401 may have the same configuration and connection relationship as those of the sensor element 1. As described above, the two adjacent drive arms 7 correspond to the one drive arm 7 of embodiment 1, and the voltages are applied in the same phase. Therefore, between the two drive arms 7, the excitation electrodes 15A are set to the same potential, and the excitation electrodes 15B are set to the same potential. The excitation electrodes 15 to be at the same potential are connected to each other, for example, by an excitation wiring portion 19.

The connection relationship between the excitation electrode 15 and the detection electrode 17 in the unit 404 will be described in the following description of the operation.

(operation of angular velocity sensor)

Fig. 9 (a) and 9 (b) are plan views schematically showing the excitation state of the piezoelectric body 403 in embodiment 4, and correspond to fig. 3 (a) and 3 (b) of embodiment 1. In these schematic views, regarding the mounting portion 411, only a part of the inner frame 23 (a part of the pair of side portions 23 a) is shown.

The excitation in each section 404 is basically the same as that of the piezoelectric body 3 in embodiment 1. However, in each unit 404, voltages are applied in the same phase so that two adjacent driving arms 7 are bent together to the same side, corresponding to one driving arm 7 of the piezoelectric body 3.

In each of the two units 404, for example, the drive arms 7 located on the same side (positive side or negative side) in the x-axis direction with respect to the detection arm 9 apply voltages in the same phase with each other so as to be bent toward the same side in the x-axis direction. Therefore, the frames 5A and 5B are flexed in opposite directions to each other. Further, the detection arms 9A and 9B are displaced in opposite directions to each other.

For the voltage application as described above, for example, in the drive arms 7(7C, 7D, 7G, and 7H, or 7E, 7F, 7I, and 7J) located on the same side in the x-axis direction with respect to the detection arm 9, the excitation electrodes 15A are set to the same potential, and the excitation electrodes 15B are set to the same potential. The excitation electrodes 15 to be at the same potential are connected to each other by, for example, a plurality of excitation wiring portions 19. All excitation electrodes 15 are connected to the drive circuit 103 (fig. 2 (b)) via two of the 6 terminals 13.

Fig. 10 (a) and 10 (b) are plan views schematically illustrating the vibration of the detection arm 9 in the sensor element 401, and correspond to fig. 4 (a) and 4 (b) of embodiment 1. In these figures, the frame 5 and the drive arm 7 are not shown in their modified form.

As described with reference to fig. 9 (a) and 9 (b), a state in which the piezoelectric body 403 is vibrating is considered. In this state, if the sensor element 401 rotates about the z-axis, the detection arm 9 vibrates in the x-axis direction due to the coriolis force in each unit 404, as in embodiment 1. At this time, since the detection arms 9A and 9B vibrate in the y-axis direction with phases displaced to opposite sides from each other, coriolis force is received on the same side with respect to the rotational direction around the z-axis. In another aspect, the detection arms 9A and 9B vibrate in the x-axis direction as if they are bent toward opposite sides from each other.

In order to add the signals generated in such detection arms 9A and 9B, for example, the detection electrode 17A of the detection arm 9A and the detection electrode 17B of the detection arm 9B are connected, and the detection electrode 17B of the detection arm 9A and the detection electrode 17A of the detection arm 9B are connected. This connection is realized by a plurality of detection wiring portions 21, for example. All the detection electrodes 17 are connected to the detection circuit 105 ((b) of fig. 2) via two of the 6 terminals 13.

(Wiring part for detection)

Fig. 11 is a plan view schematically showing the detection wiring portion 21 of the sensor element 401, and corresponds to fig. 5 (a) of embodiment 1. Fig. 12 is a bottom view schematically showing the detection wiring portion 21 in a perspective view from above, and corresponds to fig. 5 (b) of embodiment 1. However, in fig. 11, unlike (a) of fig. 5, the position of at least a part of the reference potential wiring 20 is shown as a solid line. The same applies to other drawings (fig. 13 to 16) described later, which correspond to fig. 5 a.

In each detection arm 9, detection electrodes 17A and 17B are connected to each other, as in embodiment 1. This connection is performed, for example, on the tip or root side of each detection arm 9, as in embodiment 1.

The detection electrode 17B of the detection arm 9A and the detection electrode 17A of the detection arm 9B are connected by the 1 st wiring portion 21P. The detection electrode 17A of the detection arm 9A and the detection electrode 17B of the detection arm 9B are connected by a 2 nd wiring portion 21N.

More specifically, in the illustrated example, the 1 st wiring portion 21P has a wiring main body 21a extending from the detection electrode 17B of the detection arm 9A to the-x side in the frame 5A (the 1 st portion 5A thereof) and reaching the lateral portion 23 a. The 1 st wiring portion 21P has a wiring main body 21a extending from the detection electrode 17A of the detection arm 9B to the-x side in the frame 5B (the 1 st portion 5a thereof) and reaching the lateral portion 23 a. The two wiring bodies 21a described above are joined and extend along the side portion 23 a. Although not particularly shown, the joined wiring bodies 21a reach the outer frame 27 from the inner frame 23 via the projections 25, and are connected to the terminals 13.

In the illustrated example, the 2 nd wiring portion 21N has a wiring main body 21a extending from the detection electrode 17A of the detection arm 9A to the + x side in the frame 5A (the 2 nd portion 5b thereof) and reaching the lateral portion 23 a. The wiring main body 21a further extends toward the frame 5B at the + x-side portion 23a, and then extends toward the-x side at the frame 5B (the 2 nd portion 5B thereof), and is connected to the detection electrode 17B of the detection arm 9B. The 2 nd wiring portion 21N has a wiring main body 21a extending from the detection electrode 17B of the detection arm 9B to the-x side in the frame 5B (the 1 st portion 5a thereof) and reaching the lateral portion 23 a. Although not particularly shown, the wiring main body 21a extends from the inner frame 23 to the outer frame 27 via the protrusion 25, and is connected to the terminal 13.

In addition, a portion of the 1 st wiring portion 21P extending from the detection electrode 17A of the detection arm 9B to the-x side of the frame 5B (the 1 st portion 5a thereof) and a portion of the 2 nd wiring portion 21N extending from the detection electrode 17B of the detection arm 9B to the-x side of the frame 5B (the 1 st portion 5a thereof) are arranged in parallel with each other. The length of the parallel extension is equal to or greater than 1/4 (approximately 1/2 in the illustrated example) of the length of one frame 5. Therefore, the same effects as those of embodiment 1 can be achieved in this embodiment. For example, the difference between the electric charge applied from the frame 5 to the 1 st wiring portion 21P and the electric charge applied from the frame 5 to the 2 nd wiring portion 21N can be reduced, and noise caused by flexural deformation of the frame 5 can be reduced.

More specifically, in the present embodiment, as in embodiment 1, the wiring main bodies 21a of the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in parallel with each other in the frame 5. In the present embodiment, similarly to embodiment 2, one of the 1 st wiring portion 21P and the 2 nd wiring portion 21N (the 1 st wiring portion 21P) extends from the root portion side of the detection arm 9 only to the 1 st site 5a side, and the other (the 2 nd wiring portion 21N) extends from the root portion side of the detection arm 9 only to both the 1 st site 5a side and the 2 nd site 5b side.

In the present embodiment, the relative relationship between the deformation of the portion on the positive side of the polarization axis (x axis) and the deformation of the portion on the negative side is the same for the 1 st portions 5a of the two frames 5. Therefore, the electric charges generated in the 1 st portions 5a of the two frames 5 are equal in positive and negative and equal in magnitude in many cases. The same applies to the 2 nd site 5 b. Therefore, when the 1 st and 2 nd lengths LP and LN are considered, the lengths of the 1 st and 2 nd wiring portions 21P and 21N in the entire two frames 5 can be considered.

For example, in the present embodiment, the 1 st length LP obtained by subtracting the length (0) in the 2 nd portion 5b of the 1 st wiring portion 21P from the length (2 × La) in the 1 st portion 5a of the 1 st wiring portion 21P is 2La — 0 — 2 La. The 2 nd length LN obtained by subtracting the length (2 × La) of the 2 nd site 5b of the 2 nd wiring portion 21N from the length (La) of the 1 st site 5a of the 2 nd wiring portion 21N becomes La-2La ═ La. Therefore, the difference (LP-LN) between the two becomes 2La- (-La) ═ 3 La.

On the other hand, as a comparative example, for example, a configuration may be considered in which the 2 nd wiring portion 21N is connected to the terminal 13 by extending the wiring main body 21a of the side portion 23a located on the + x side to the protrusion 25 without providing the wiring main body 21a extending from the detection electrode 17B of the detection arm 9B to the-x side in the frame 5B (I-th portion 5a thereof). In this structure, the 1 st length LP is the same as in the present embodiment. The 2 nd length LP is-2 La. Therefore, the difference (LP-LN) between the two becomes 2La- (-2La) ═ 4 La.

Therefore, in the present embodiment, it is understood that the difference between the 1 st length LP and the 2 nd length LN is reduced by providing the wiring main body 21a extending from the detection electrode 17B of the detection arm 9B to the-x side of the frame 5B (the 1 st portion 5a thereof) as compared with the above-described comparative example. That is, it can be confirmed that the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in parallel with each other in the frame 5, and noise can be reduced.

In the comparative example, actually, the difference between the 1 st length LP and the 2 nd length LN may be undesirably reduced by the crossing of the detection wiring portion 21 on the root side of the detection arm 9. However, it is considered that the difference in this case does not become shorter than 4La — La/2 — 7 La/2.

[ 5 th embodiment ]

Fig. 13 is a plan view schematically showing the detection wiring portion 21 of the sensor element 501 according to embodiment 5, and corresponds to fig. 5 (a) of embodiment 1. The bottom view of the sensor element 501 is the same as that of fig. 12 according to embodiment 4.

As is clear, the configuration of the detection wiring portion 21 of the sensor element 501 is such that, in the 2 nd wiring portion 21N of embodiment 4 (fig. 11), the wiring main body 21a reaching the detection electrode 17B of the detection arm 9B from the detection electrode 17A of the detection arm 9A via the + x-side portion 23a is changed to a configuration via the-x-side portion 23 a. As a result, the main wiring body 21a and the main wiring body 21a of the 1 st wiring portion 21P extending from the detection electrode 17B of the detection arm 9A to the detection electrode 17A of the detection arm 9B extend in parallel in the 1 st portion 5A of the frames 5A and 5B.

In such a configuration, as in the other embodiments, the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in parallel over 1/4 or more of the length of the frame 5, and therefore, the same effects as those of the 1 st embodiment can be achieved. For example, the difference between the electric charge applied from the frame 5 to the 1 st wiring portion 21P and the electric charge applied from the frame 5 to the 2 nd wiring portion 21N can be reduced, and noise caused by flexural deformation of the frame 5 can be reduced.

More specifically, in the present embodiment, as in embodiment 1, the wiring main bodies 21a of the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in parallel with each other in the frame 5. In the present embodiment, as in embodiment 1, both the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend from the root portion side of the detection arm 9 toward the 1 st site 5a side.

In the present embodiment, the 1 st length LP obtained by subtracting the length (0) at the 2 nd site 5b of the 1 st wiring portion 21P from the length (2 × La) at the 1 st site 5a of the 1 st wiring portion 21P is 2La-0 — 2 La. The 2 nd length LN obtained by subtracting the length (0) at the 2 nd site 5b of the 2 nd wiring portion 21N from the length (3La) at the 1 st site 5a of the 2 nd wiring portion 21N becomes 3La-0, which is 3 La. Therefore, the difference (LP-LN) between the two is 2La-3La ═ La. This length (absolute value) is shorter than the difference (3La) between the 1 st length LP and the 2 nd length LN of embodiment 4. That is, in the present embodiment, noise can be further reduced as compared with embodiment 4.

The difference between the 1 st length LP and the 2 nd length LN in the present embodiment and the 6 th to 8 th embodiments described later is shorter than that in the 4 th embodiment. In contrast to embodiment 4, the 5 th to 8 th embodiments can be said to have a difference between the 1 st length LP and the 2 nd length LN of 5La/2 (3La — La/2) or less, considering the crossing of the detection wiring portion 21 on the root side of the detection arm 9. In addition, it can be said that the present embodiment is an embodiment in which the difference (absolute value) between the 1 st length LP and the 2 nd length LN is 3La/2 or less.

In the present embodiment, the wiring main body 21a of the 2 nd wiring portion 21N reaching the terminal 13 extends from the detection electrode 17B of the detection arm 9B to the-x side in the frame 5B and reaches the lateral portion 23a, where it extends toward the protrusion 25 not shown. However, the wiring main body 21a may extend from the + x-side detection electrode 17B to the + x side, reach the lateral portion 23a, and extend toward the protrusion 25. In this case, the absolute value of the difference between the 1 st length LP and the 2 nd length LN is also La.

[ 6 th embodiment ]

Fig. 14 is a plan view schematically showing the detection wiring portion 21 of the sensor element 601 according to embodiment 6, and corresponds to fig. 5 (a) of embodiment 1. The bottom view of the sensor element 601 is the same as that of fig. 12 according to embodiment 4.

In a straightforward manner, the detection wiring portion 21 of the sensor element 601 is configured by adding the adjustment wiring 21B extending to the 2 nd portion 5B of the frame 5B to the 2 nd wiring portion 21N of embodiment 5 (fig. 13). More specifically, one end of the adjustment wire 21B is connected to a main wiring body 21a connecting the detection electrode 17A of the detection arm 9A and the detection electrode 17B of the detection arm 9B, and the other end is an open end.

The adjustment wires 21b according to embodiments 2 (fig. 7a) and 3 (fig. 7b) are configured as portions extending in parallel with other wire portions (wire main bodies 21a) having different potentials. On the other hand, the adjustment wiring 21b of the present embodiment is not formed to extend in parallel with another wiring portion having a different potential. The adjustment wiring 21b contributes to reducing the difference between the 1 st length LP and the 2 nd length LN. Thus, for example, the difference between the electric charge applied from the frame 5 to the 1 st wiring portion 21P and the electric charge applied from the frame 5 to the 2 nd wiring portion 21N can be reduced, and noise caused by flexural deformation of the frame 5 can be reduced.

Specifically, in the present embodiment, the 1 st length LP obtained by subtracting the length (0) in the 2 nd portion 5b of the 1 st wiring portion 21P from the length (2 × La) in the 1 st portion 5a of the 1 st wiring portion 21P is 2La-0 — 2 La. The 2 nd length LN obtained by subtracting the length (La) of the 2 nd site 5b of the 2 nd wiring portion 21N from the length (3La) of the 1 st site 5a of the 2 nd wiring portion 21N becomes 3La — La equal to 2 La. Therefore, the difference (LP-LN) between the two becomes 2La-2La ═ 0. This length is shorter than the difference (La) between the 1 st length LP and the 2 nd length LN of embodiment 5. That is, in the present embodiment, noise can be further reduced as compared with embodiment 5.

As can be understood from embodiment 5 (fig. 13), it may be difficult to make the difference between the 1 st length LP and the 2 nd length LN 0 by only adjusting the position of the wiring main body 21 a. In such a case, as can be understood from the present embodiment, the difference between the 1 st length LP and the 2 nd length LN can be made 0 by providing the adjustment wiring 21 b.

In the present embodiment, if the intersection of the detection wiring portion 21 on the root side of the detection arm 9 is considered, it can be said that the difference between the 1 st length LP and the 2 nd length LN is La/2 or less, in comparison with the embodiment 5. In the present embodiment, as in embodiment 1, the wiring main bodies 21a of the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in parallel with each other in the frame 5. In the present embodiment, similarly to embodiment 2 (fig. 7 (a)), the 1 st wiring portion 21P extends from the root side of the detection arm 9 only to the 1 st site 5a side, and the 2 nd wiring portion 21N extends from the root side of the detection arm 9 to both the 1 st site 5a side and the 2 nd site 5b side.

[ 7 th embodiment ]

Fig. 15 is a plan view schematically showing the detection wiring portion 21 of the sensor element 701 according to embodiment 7, and corresponds to fig. 5 (a) of embodiment 1. The bottom view of the sensor element 701 is the same as that of fig. 12 according to embodiment 4.

In a straightforward manner, the configuration of the detection wiring portion 21 of the sensor element 701 is such that the adjustment wiring 21B extending to the 2 nd site 5B of the frame 5B is added to the 1 st wiring portion 21P of embodiment 4 (fig. 11). More specifically, one end of the adjustment wire 21B is connected to the main wiring body 21a that connects the detection electrode 17B of the detection arm 9A and the detection electrode 17A of the detection arm 9B, and the other end is an open end.

By adding the adjustment wire 21b, the difference between the 1 st length LP and the 2 nd length LN is shorter in the present embodiment than in the 4 th embodiment. Specifically, in the present embodiment, the 1 st length LP obtained by subtracting the length (La) of the 2 nd portion 5b of the 1 st wiring portion 21P from the length (2 × La) of the 1 st portion 5a of the 1 st wiring portion 21P is 2La — La ═ La. The 2 nd length LN obtained by subtracting the length (2 × La) of the 2 nd site 5b of the 2 nd wiring portion 21N from the length (La) of the 1 st site 5a of the 2 nd wiring portion 21N becomes La-2La ═ La. Therefore, the difference (LP-LN) between the two becomes La- (-La) ═ 2 La. This length is shorter than the difference (3La) between the 1 st length LP and the 2 nd length LN of embodiment 4. That is, in the present embodiment, noise can be further reduced as compared with embodiment 4.

In the case where noise is reduced by the adjustment wire 21b in this way, as described in embodiments 2 and 3 (fig. 7 (a) and 7 (b)), the degree of design change of the wire main body 21a and the like with respect to the initial design (fig. 11 in this case) can be reduced.

In the present embodiment, as in embodiment 1, the wiring main bodies 21a of the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend in parallel with each other in the frame 5. In the present embodiment, similarly to embodiments 2 and 3 (fig. 7 (a) and 7 (b)), the main wiring body 21a and the adjustment wiring 21b of the wiring portions (21P and 21N) having different potentials extend in parallel with each other in the frame 5. In the present embodiment, as in embodiment 3, the 1 st wiring portion 21P and the 2 nd wiring portion 21N extend from the root side of the detection arm 9 to both the 1 st site 5a side and the 2 nd site 5b side.

[ 8 th embodiment ]

Fig. 16 is a plan view schematically showing the detection wiring portion 21 of the sensor element 801 according to embodiment 8, and corresponds to fig. 5 (a) of embodiment 1. The bottom view of the sensor element 801 is the same as that of fig. 12 according to embodiment 4.

In a straightforward manner, the configuration of the detection wiring portion 21 of the sensor element 801 is such that the adjustment wiring 21b extending to the 2 nd site 5b of the frame 5A is added to the 1 st wiring portion 21P of embodiment 7 (fig. 15). More specifically, one end of the adjustment wire 21B is connected to the main wiring body 21a that connects the detection electrode 17B of the detection arm 9A and the detection electrode 17A of the detection arm 9B, and the other end is an open end.

By adding the adjustment wire 21b, the difference between the 1 st length LP and the 2 nd length LN is shorter in the present embodiment than in the 7 th embodiment. Specifically, in the present embodiment, the 1 st length LP obtained by subtracting the length (2 × La) of the 2 nd portion 5b of the 1 st wiring portion 21P from the length (2 × La) of the 1 st portion 5a of the 1 st wiring portion 21P is set to 2La — 2La equal to 0. The 2 nd length LN obtained by subtracting the length (2 × La) of the 2 nd site 5b of the 2 nd wiring portion 21N from the length (La) of the 1 st site 5a of the 2 nd wiring portion 21N becomes La-2La ═ La. Therefore, the difference (LP-LN) between the two becomes 0- (-La) ═ La. This length is shorter than the difference (2La) between the 1 st length LP and the 2 nd length LN of embodiment 7. That is, in the present embodiment, noise can be further reduced as compared with embodiment 7.

[ 9 th embodiment ]

Fig. 17 (a) is a perspective view similar to fig. 2 (a) showing a sensor element 901 according to embodiment 9 in an enlarged manner. Fig. 17 (b) is a view similar to fig. 2 (b) showing an angular velocity sensor 951 according to embodiment 9, and includes a cross-sectional view taken along lines xviiib to xviiib corresponding to fig. 17 (a).

The angular velocity sensor 951 according to embodiment 2 vibrates the pair of drive arms 7 in the x-axis direction, thereby bending (vibrating) the frame 5 and further displacing (vibrating) the detection arm 9 in the y-axis direction, as in the angular velocity sensor 51 according to embodiment 1. Then, the coriolis force is directly applied to the detection arm 9. However, the angular velocity sensor 951 detects rotation about the x-axis relative to detection of rotation about the z-axis of the angular velocity sensor 51. Specifically, as shown below.

The sensor element 901 includes a piezoelectric body 3, a plurality of excitation electrodes 15, a plurality of detection electrodes 917(917A and 917B), a plurality of terminals 13 (see fig. 1), a plurality of excitation wiring portions 19, and a plurality of detection wiring portions 21. These elements may be basically the same as those of the sensor element 1 according to embodiment 1, except for the plurality of detection electrodes 917 (and the detection arm 9 of the detection wiring portion 21 and the specific positions of the surroundings thereof). Fig. 1 can be seen as a perspective view showing a sensor element 901.

However, unlike embodiment 1, the present embodiment is preferably configured such that the detection arm 9 vibrates in the z-axis direction due to the coriolis force. Based on such differences, various sizes may be different from embodiment 1.

The detection electrode 917A is provided in the detection arm 9 in a region on the positive side in the z-axis direction (for example, on the positive side with respect to the center of the surface) on the surface facing the negative side in the x-axis direction, and in a region on the negative side in the z-axis direction (for example, on the negative side with respect to the center of the surface) on the surface facing the positive side in the x-axis direction. The detection electrode 917B is provided in the detection arm 9 in a region on the negative side in the z-axis direction (for example, on the negative side with respect to the center of the surface) on the surface facing the negative side in the x-axis direction, and in a region on the positive side in the z-axis direction (for example, on the positive side with respect to the center of the surface) on the surface facing the positive side in the x-axis direction.

The detection electrodes 917A and 917B are spaced at appropriate intervals in each side of the detection arm 9 so as not to short-circuit each other, and extend along the detection arm 9. The two detection electrodes 917A are connected to each other, for example, by the detection wiring portion 21. The two detection electrodes 917B are connected to each other, for example, by the detection wiring portion 21.

In the arrangement and connection relationship of the detection electrodes 917, if the detection arm 9 is deformed in the z-axis direction, for example, an electric field parallel to the z-axis direction is generated. That is, a voltage is generated between the detection electrode 917A and the detection electrode 917B on each side surface of the detection arm 9. The orientation of the electric field is determined by the orientation of the polarization axis and the orientation of the bend (positive side or negative side in the z-axis direction), and is opposite to each other in the positive side portion and the negative side portion in the x-axis direction. The voltage (electric field) is output to the detection electrode 917A and the detection electrode 917B. If the detection arm 9 vibrates in the z-axis direction, the voltage is detected as an alternating voltage. As for the electric field, as described above, the electric field parallel to the z-axis direction may be dominant, and the ratio of the electric fields parallel to the x-axis direction and oriented opposite to each other in the positive side portion and the negative side portion in the z-axis direction may be large. In short, a voltage corresponding to the flexural deformation of the detection arm 9 in the z-axis direction is generated between the detection electrodes 917A and 917B.

Although not particularly shown, the detection arm 9 may be formed with one or more through grooves (slits) that penetrate from the upper surface to the lower surface and extend in the longitudinal direction of the detection arm 9. Further, the detection electrodes 917A and 917B may be arranged and connected to the plurality of elongated portions divided by the through-grooves, as in the detection arm 9 of the illustrated example. In this case, the entire area becomes larger than that in the case where only the plurality of detection electrodes 917 are provided on the outer side surface of the detection arm 9. As a result, the electric charge generated in the detection arm 9 can be efficiently extracted as an electric signal.

The plurality of detection wiring portions 21 connect the detection electrodes 17 to each other as described above. Further, the plurality of detection wiring portions 21 connect the detection electrodes 17 divided into 2 groups from the viewpoint of potential and the two terminals 13. The plurality of detection line portions 21 include the 1 st line portion 21P and the 2 nd line portion 21N, as in the above embodiments. The arrangement of the frame 5 in the 1 st wiring portion 21P and the 2 nd wiring portion 21N may be the same as any of the arrangements shown in the embodiments described above.

(operation of angular velocity sensor)

The excitation of the piezoelectric body 3 in embodiment 9 is the same as that in embodiment 1. Fig. 3 (a) and 3 (b) can be regarded as diagrams showing the excitation state of the piezoelectric body 3 in embodiment 9. Therefore, the pair of drive arms 7 vibrate in the x-axis direction so as to approach each other and move away from each other in the reverse direction, and the detection arm 9 displaces (vibrates) in the y-axis direction.

Fig. 18 (a) and 18 (b) are schematic perspective views for explaining the vibration of the detection arm 9 caused by the coriolis force. Fig. 18 (a) and 18 (b) correspond to the excitation states of fig. 3 (a) and 3 (b).

As described with reference to fig. 3 (a) and 3 (b), a state in which the piezoelectric body 3 is vibrating is considered. In this state, if the sensor element 901 rotates about the x axis, the detection arm 9 vibrates (displaces) in the y axis direction, and therefore vibrates (deforms) in a direction (z axis direction) orthogonal to the rotation axis (x axis) and the vibration direction (y axis) due to the coriolis force. The signal (voltage) generated by the deformation is extracted by the detection electrode 17 as described above. The coriolis force (the voltage of the detected signal) increases as the angular velocity increases. Thereby, the angular velocity can be detected.

The present invention is not limited to the above embodiments, and can be implemented in various forms.

The above-described embodiments may be appropriately combined. The configuration in which two adjacent drive arms vibrate in phase and vibrate like one arm, such as embodiment 4, can also be applied to the embodiment in which the frame is one, such as embodiment 1. On the other hand, in the configuration in which the two frames are provided as in embodiment 4, only one pair of driving arms may be provided in each frame. For example, the detection electrode according to embodiment 9 may be applied to a structure in which two frames are provided. In this case, the two detection arms vibrate in the opposite side to each other in the z-axis direction by rotating around the x-axis. Thus, the detection electrode 917A of one detection arm and the detection electrode 917B of the other detection arm are connected.

In embodiment 4 and the like, the two units 404 are supported by a common support portion so as to face the side opposite to the side from which the drive arm and the detection arm extend. However, the two units 404 may be supported by a common support portion with the extended sides of the drive arm and the detection arm facing each other (see fig. 8 of patent document 1). The drive arm and the detection arm may extend from one frame to both sides in a direction intersecting the frame (see fig. 9 of patent document I). In addition, the two units 404 may have the drive arms and the detection arms extending from the opposite sides, and the distal ends of the drive arms may be connected to each other (see patent document 2).

Among the length, width, and thickness of the wiring portion, the length greatly affects the magnitude of the electric charge applied to the wiring portion by the deflection deformation of the frame. The width and thickness of the wiring portion are also regulated by design values of the excitation electrode and the detection electrode, accuracy of a process for forming the wiring, and the like. Therefore, basically, as described in the present embodiment, adjustment of noise reduction due to flexural deformation of the frame can be realized with the length of the wiring portion in the 1 st portion and the 2 nd portion of the frame as a reference. However, the width and thickness of the 1 st and 2 nd portions of the wiring portion may be adjusted.

The sensor element or the angular velocity sensor may be formed as part of a MEMS (Micro Electro Mechanical Systems). In this case, the piezoelectric body of the sensor element may be mounted on a MEMS substrate, or the MEMS substrate may be formed of the piezoelectric body and a part of the piezoelectric body may be used to form the piezoelectric body of the sensor element.

-description of symbols-

1: a sensor element; 3: a piezoelectric body; 5: a frame; 7: a drive arm; 9: a detection arm; 13: a terminal (terminal for excitation; terminal for 1 st detection or terminal for 2 nd detection); 15: an excitation electrode; 17A: a detection electrode (1 st detection electrode or 2 nd detection electrode); 17B: a detection electrode (2 nd detection electrode or 1 st detection electrode); 19: a wiring part for excitation; 21P: a 1 st wiring portion (a 1 st detection wiring portion); 21N: a 2 nd wiring portion (a 2 nd wiring portion for detection); 51: an angular velocity sensor; 103: a drive circuit; 105: a detection circuit.