阅读说明：本技术 角速度传感器以及传感器元件 (Angular velocity sensor and sensor element ) 是由 副岛宗高 于 2020-05-26 设计创作，主要内容包括：角速度传感器的传感器元件具有压电体、多个激励电极和多个检测电极。压电体具有至少两根驱动臂以及检测臂。多个激励电极在x轴方向以相互相反的相位来激励两根驱动臂。多个检测电极取出通过检测臂的x轴方向或者z轴方向的振动而产生的信号。压电体还具有：框部、从框部向外侧延伸并支承框部的保持部、连接于保持部的与框部侧相反的一侧的支承部。两根驱动臂以及检测臂从框部延伸。(A sensor element of an angular velocity sensor has a piezoelectric body, a plurality of excitation electrodes, and a plurality of detection electrodes. The piezoelectric body has at least two driving arms and a detection arm. The plurality of excitation electrodes excite the two drive arms in mutually opposite phases in the x-axis direction. The plurality of detection electrodes extract signals generated by the vibration of the detection arm in the x-axis direction or the z-axis direction. The piezoelectric body further has: the frame portion, a holding portion extending outward from the frame portion and supporting the frame portion, and a support portion connected to the holding portion on a side opposite to the frame portion side. Two driving arms and a detection arm extend from the frame portion.)

1. An angular velocity sensor having:

a sensor element; and

a mounting base supporting the sensor element,

the sensor element has:

a piezoelectric body having at least two drive arms extending in parallel with each other in a y-axis direction at positions separated from each other in an x-axis direction of an orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction;

a plurality of excitation electrodes positioned on the two drive arms so as to excite the two drive arms in an arrangement and a connection relationship in which the two drive arms are arranged in an x-axis direction with mutually opposite phases; and

a plurality of detection electrodes disposed on the detection arm so as to extract a signal generated by vibration of the detection arm in an x-axis direction or a z-axis direction,

the piezoelectric body further includes, as viewed in the z-axis direction:

a frame portion that constitutes an opening and includes, as a part of a periphery of the opening, a base portion having an x-axis direction as a longitudinal direction and an opposing portion that is located on a side opposite to the base portion with the opening interposed therebetween;

a holding portion extending from the opposing portion to an outside of the opening and supporting the frame portion; and

a supporting portion connected to the holding portion on a side opposite to the opposing portion side and supported by the mounting base,

the two drive arms extend from portions of the opposing portion that are located on both sides in the x-axis direction with respect to a connecting position of the opposing portion and the holding portion,

the detection arm extends from the base.

2. An angular velocity sensor having:

a sensor element; and

a mounting base supporting the sensor element,

the sensor element has:

a piezoelectric body having at least two drive arms extending in parallel with each other in a y-axis direction at positions separated from each other in an x-axis direction of an orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction;

a plurality of excitation electrodes positioned on the two drive arms so as to excite the two drive arms in an arrangement and a connection relationship in which the two drive arms are arranged in an x-axis direction with mutually opposite phases; and

a plurality of detection electrodes disposed on the detection arm so as to extract a signal generated by vibration of the detection arm in an x-axis direction or a z-axis direction,

the piezoelectric body further includes, as viewed in the z-axis direction:

a frame portion that constitutes an opening and includes, as a part of a periphery of the opening, a base portion having an x-axis direction as a longitudinal direction and an opposing portion that is located on a side opposite to the base portion with the opening interposed therebetween;

a holding portion extending from the opposing portion to an outside of the opening and supporting the frame portion; and

a supporting portion connected to the holding portion on a side opposite to the opposing portion side and supported by the mounting base,

the two drive arms extend from the base portion,

the detection arm extends from the base between the two drive arms.

3. The angular velocity sensor according to claim 1 or 2,

the frame portion is supported at one point by the holding portion.

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

the two driving arms extend inwards to the opening,

the detection arm extends into the opening.

5. The angular velocity sensor according to claim 4,

all of the driving arm and the detection arm extend into the opening.

6. The angular velocity sensor according to any one of claims 1 to 5,

the piezoelectric body has two units each including the holding portion, the frame portion, the two driving arms, and the detection arm,

the two units face the holding portions on the sides extending from the frame portion.

7. The angular velocity sensor according to claim 2,

the piezoelectric body further has:

a 2 nd drive arm extending in the y-axis direction from the opposing portion; and

a 2 nd detection arm extending in the y-axis direction from the opposing portion,

the sensor element has:

a plurality of 2 nd excitation electrodes disposed in the 2 nd drive arm so as to excite the 2 nd drive arm in the x-axis direction; and

and a plurality of 2 nd detection electrodes disposed in the 2 nd detection arm in such a manner as to extract a signal generated by the z-axis vibration of the 2 nd detection arm.

8. A sensor element having:

a piezoelectric body having at least two drive arms extending in parallel with each other in a y-axis direction at positions separated from each other in an x-axis direction of an orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction from the base;

a plurality of excitation electrodes positioned on the two drive arms so as to excite the two drive arms in an arrangement and a connection relationship in which the two drive arms are arranged in an x-axis direction with mutually opposite phases;

a plurality of detection electrodes disposed on the detection arm so as to extract a signal generated by vibration of the detection arm in an x-axis direction or a z-axis direction; and

a plurality of terminals connected to the excitation electrode and the detection electrode,

the piezoelectric body further includes, as viewed in the z-axis direction:

a frame portion that constitutes an opening and includes, as a part of a periphery of the opening, a base portion having an x-axis direction as a longitudinal direction and an opposing portion that is located on a side opposite to the base portion with the opening interposed therebetween;

a holding portion extending from the opposing portion to an outside of the opening and supporting the frame portion; and

a support portion connected to the holding portion on a side opposite to the opposing portion side, the plurality of terminals being positioned in the support portion,

the two drive arms extend from portions of the opposing portion that are located on both sides in the x-axis direction with respect to a connecting position of the opposing portion and the holding portion,

the detection arm extends from the base.

9. A sensor element having:

a piezoelectric body having at least two drive arms extending in parallel with each other in a y-axis direction at positions separated from each other in an x-axis direction of an orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction;

a plurality of excitation electrodes positioned on the two drive arms so as to excite the two drive arms in an arrangement and a connection relationship in which the two drive arms are arranged in an x-axis direction with mutually opposite phases;

a plurality of detection electrodes disposed on the detection arm so as to extract a signal generated by vibration of the detection arm in an x-axis direction or a z-axis direction; and

a plurality of terminals connected to the excitation electrode and the detection electrode,

the piezoelectric body further includes, as viewed in the z-axis direction:

a frame portion that constitutes an opening and includes, as a part of a periphery of the opening, a base portion having an x-axis direction as a longitudinal direction and an opposing portion that is located on a side opposite to the base portion with the opening interposed therebetween;

a holding portion extending from the opposing portion to an outside of the opening and supporting the frame portion; and

a support portion connected to the holding portion on a side opposite to the opposing portion side, the plurality of terminals being positioned in the support portion,

the two drive arms extend from the base portion,

the detection arm extends from the base between the two drive arms.

10. The sensor element of claim 8 or 9, wherein,

the frame portion is supported at one point by the holding portion.

Technical Field

The present disclosure relates to an angular velocity sensor that detects an angular velocity and a sensor element included in the angular velocity sensor.

Background

As an angular velocity sensor (gyroscope), a so-called piezoelectric vibration type sensor is known (for example, patent documents 1 to 3 listed below). In this sensor, an alternating voltage is applied to a piezoelectric body to excite the piezoelectric body. When the excited piezoelectric body rotates, 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 also vibrates by the coriolis force. Then, an electrical signal generated by the deformation of the piezoelectric body due to the coriolis force is detected, whereby 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. Specifically, the piezoelectric body includes: the detection arm includes a base portion having an x-axis direction of an orthogonal coordinate system xyz as a longitudinal direction, a pair of drive arms extending in parallel to each other in a y-axis direction from the base portion at positions separated from each other in the x-axis direction, and a detection arm extending in the y-axis direction from the base portion at a position serving as a center of the pair of drive arms in the x-axis direction. The pair of drive arms are excited to deflect in the x-axis direction toward opposite sides from each other. Thereby, the base portion vibrates so as to be deflected in the y-axis direction. Further, the detection arm generates vibration that displaces in the y-axis direction. In the case where the sensor is rotated about the z-axis, the detection arm is vibrated in the x-axis direction by the coriolis force. In the case where the sensor is rotated about the x-axis, the detection arm is vibrated in the z-axis direction by the coriolis force.

Fig. 4 to 8 of patent document 3 disclose a sensor of a vibration system similar to the vibration system of patent document 1. The piezoelectric body of the sensor has a frame portion. The frame partially includes a base portion, and surrounds the pair of driving arms and the detection arm.

Prior art documents

Patent document

Patent document 1: international publication No. 2018/021166

Patent document 2: international publication No. 2018/021167

Patent document 3: international publication No. 2019/044697

Disclosure of Invention

An angular velocity sensor according to an aspect of the present disclosure includes a sensor element and a mounting base supporting the sensor element. The sensor element has a piezoelectric body, a plurality of excitation electrodes, and a plurality of detection electrodes. The piezoelectric body has: at least two drive arms extending in parallel with each other in the y-axis direction at positions separated from each other in the x-axis direction of the orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction. The plurality of excitation electrodes are located on the two drive arms in an arrangement and connection relationship for exciting the two drive arms with mutually opposite phases in the x-axis direction. The plurality of detection electrodes are disposed in the detection arm so as to extract a signal generated by vibration of the detection arm in the x-axis direction or the z-axis direction. The piezoelectric body further includes a frame portion, a holding portion, and a support portion. The frame portion forms an opening when viewed in the z-axis direction. The frame portion includes, as a part of a periphery of the opening: a base portion having a longitudinal direction in the x-axis direction, and an opposing portion located on the opposite side of the base portion with the opening therebetween. The holding portion extends from the opposing portion to an outside of the opening and supports the frame portion. The support portion is coupled to the holding portion on a side opposite to the opposing portion, and is supported by the mounting base. The two drive arms extend from portions of the opposing portion that are located on both sides in the x-axis direction with respect to a connecting position of the opposing portion and the holding portion. The detection arm extends from the base.

An angular velocity sensor according to an aspect of the present disclosure includes a sensor element and a mounting base supporting the sensor element. The sensor element has a piezoelectric body, a plurality of excitation electrodes, and a plurality of detection electrodes. The piezoelectric body has: at least two drive arms extending in parallel with each other in the y-axis direction at positions separated from each other in the x-axis direction of the orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction. The plurality of excitation electrodes are located on the two drive arms in an arrangement and connection relationship for exciting the two drive arms with mutually opposite phases in the x-axis direction. The plurality of detection electrodes are disposed in the detection arm in such a manner that the detection arm takes out electric charges when vibrating in the x-axis direction or the z-axis direction. The piezoelectric body further includes a frame portion, a holding portion, and a support portion. The frame portion forms an opening when viewed in the z-axis direction. The frame portion includes, as a part of a periphery of the opening: a base portion having a longitudinal direction in the x-axis direction, and an opposing portion located on the opposite side of the base portion with the opening therebetween. The holding portion extends from the opposing portion to an outside of the opening and supports the frame portion. The support portion is coupled to the holding portion on a side opposite to the opposing portion, and is supported by the mounting base. The two drive arms extend from the base. The detection arm extends from the base between the two drive arms.

A sensor element according to an aspect of the present disclosure includes a piezoelectric body, a plurality of excitation electrodes, a plurality of detection electrodes, and a plurality of terminals. The piezoelectric body has: at least two drive arms extending in parallel with each other in the y-axis direction at positions separated from each other in the x-axis direction of the orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction from the base. The plurality of excitation electrodes are located on the two drive arms in an arrangement and connection relationship for exciting the two drive arms with mutually opposite phases in the x-axis direction. The plurality of detection electrodes are disposed in the detection arm so as to extract a signal generated by vibration of the detection arm in the x-axis direction or the z-axis direction. The plurality of terminals are connected to the excitation electrode and the detection electrode. The piezoelectric body further includes a frame portion, a holding portion, and a support portion. The frame portion forms an opening when viewed in the z-axis direction. The frame portion includes, as a part of a periphery of the opening: a base portion having a longitudinal direction in the x-axis direction, and an opposing portion located on the opposite side of the base portion with the opening therebetween. The holding portion extends from the opposing portion to an outside of the opening and supports the frame portion. The support portion is connected to the holding portion on the side opposite to the opposing portion, and the plurality of terminals are provided. The two drive arms extend from portions of the opposing portion that are located on both sides in the x-axis direction with respect to a connecting position of the opposing portion and the holding portion. The detection arm extends from the base.

A sensor element according to an aspect of the present disclosure includes a piezoelectric body, a plurality of excitation electrodes, a plurality of detection electrodes, and a plurality of terminals. The piezoelectric body has: at least two drive arms extending in parallel with each other in the y-axis direction at positions separated from each other in the x-axis direction of the orthogonal coordinate system xyz, and a detection arm extending in the y-axis direction. The plurality of excitation electrodes are located on the two drive arms in an arrangement and connection relationship for exciting the two drive arms with mutually opposite phases in the x-axis direction. The plurality of detection electrodes are disposed in the detection arm in such a configuration as to extract electric charges when the detection arm vibrates in the x-axis direction or the z-axis direction. The plurality of terminals are connected to the excitation electrode and the detection electrode. The piezoelectric body further includes a frame portion, a holding portion, and a support portion. The frame portion forms an opening when viewed from the z-axis direction. The frame portion includes, as a part of a periphery of the opening: a base portion having a longitudinal direction in the x-axis direction, and an opposing portion located on the opposite side of the base portion with the opening therebetween. The holding portion extends from the opposing portion to an outside of the opening and supports the frame portion. The support portion is connected to the holding portion on the side opposite to the opposing portion, and the plurality of terminals are provided. The two drive arms extend from the base. The detection arm extends from the base between the two drive arms.

Drawings

Fig. 1 is a plan view showing the inside of an angular velocity sensor according to embodiment 1.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a perspective view showing a structure of a sensor element included in the angular velocity sensor of fig. 1.

Fig. 4 (a) is a perspective view showing a part of the sensor element of fig. 3 in an enlarged manner, and fig. 4 (b) is a cross-sectional view taken along line IVb-IVb of fig. 4 (a).

Fig. 5 (a) and 5 (b) are schematic diagrams for explaining vibrations related to excitation of the sensor element of fig. 3.

Fig. 6 (a) and 6 (b) are schematic diagrams for explaining the vibration involved in the detection of the sensor element of fig. 3.

Fig. 7 (a) is an enlarged perspective view of a part of the sensor element according to embodiment 2, and fig. 7 (b) is a cross-sectional view taken along line VIIb-VIIb in fig. 7 (a).

Fig. 8 (a) and 8 (b) are schematic diagrams for explaining the vibration related to the detection of the sensor element according to embodiment 2.

Fig. 9 is a perspective view showing the structure of a sensor element according to embodiment 3.

Fig. 10 is a plan view showing the structure of a sensor element according to embodiment 4.

Fig. 11 is a plan view showing the shape of the piezoelectric body according to modification 1.

Fig. 12 (a), 12 (b), 12 (c) and 12 (d) are plan views showing the shapes of a part of the piezoelectric body according to the 2 nd to 4 th modifications.

Fig. 13 is a plan view showing the inside of the angular velocity sensor according to embodiment 5.

Fig. 14 (a) and 14 (b) are schematic diagrams for explaining the vibration related to the excitation of the angular velocity sensor of fig. 13.

Fig. 15 is a plan view showing the shape of a piezoelectric body according to a modification of embodiment 5.

Detailed Description

The contents of patent documents 1 to 3 can be cited by reference (Incorporation by reference). Further, the contents of international publication nos. 2018/139396, 2019/021860, 2019/044696 and 2019/044697 to which the inventors of the present application refer may also be incorporated by reference.

Embodiments according to the present disclosure will be described below with reference to the drawings. The following figures are schematic. Therefore, details may be omitted, and the size ratio and the like may not always match the actual situation. Further, the dimensional ratios of the drawings are not necessarily the same.

For convenience of explanation, an orthogonal coordinate system xyz is given to each figure. 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 the electrical axis, mechanical axis, and optical axis representing the crystal. Although the sensor element may be used with any direction as upward or downward, the term "upper surface" or "lower surface" may be used hereinafter for convenience, with the positive side in the z-axis direction being referred to as upward. In this case, the term "in a plane view" means a view in the z-axis direction unless otherwise specified.

In the same or similar structure, like the "drive arm 13A" and the "drive arm 13B", reference characters of different letters may be given, and in this case, the "drive arm 13" alone may not be distinguished from each other.

The following description of embodiment 2 basically describes the differences from the previously described embodiments. The items not specifically mentioned are the same as those in the embodiment (or the modification) described above, or can be analogized from those in the embodiment described above. In addition, a common reference numeral may be assigned to a corresponding (same or similar) structure among the plurality of embodiments even if the shape or the like is different.

[ embodiment 1 ]

(integral structure of angular velocity sensor)

Fig. 1 is a plan view showing a schematic configuration of an inside of an angular velocity sensor 51 (hereinafter, an "angular velocity" may be omitted) according to an embodiment of the present disclosure. Fig. 2 is a sectional view taken along line II-II of fig. 1.

In the present embodiment, the sensor 51 is configured to detect an angular velocity around the z-axis. The sensor 51 is an electronic component having a substantially thin rectangular parallelepiped shape as a whole, for example. The size thereof may be appropriately set.

The sensor 51 includes, for example, a sensor element 1 directly responsible for detecting angular velocity, and a package 53 encapsulating the sensor element 1. The package 53 contributes to, for example, protection of the sensor element 1 and electrical connection between the sensor element 1 and a circuit board, not shown, on which the sensor 51 is mounted.

Unlike the illustrated example, the sensor 51 may have electronic components such as an ic (integrated circuit) in addition to the sensor element 1.

(packaging piece)

The package 53 may have a known structure, and various structures are provided. In the illustrated example, the package 53 includes: a mounting base 55 on which the sensor element 1 is mounted, and a lid 57 (fig. 2) joined to the mounting base 55 so as to seal the sensor element 1. The mounting base 55 has, for example, a recess 55r for housing the sensor element 1. The lid 57 closes the recess 55 r.

The mounting substrate 55 includes, for example: an insulating base 55a having a recess 55r, and a plurality of (for example, 4 or more) pads 55b (fig. 2) located on the bottom surface of the recess 55 r. The sensor element 1 is arranged to face the bottom surface of the recess 55r, and is bonded to the plurality of pads 55b via a plurality of conductive bumps 59 (fig. 2). Thereby, the sensor element 1 is electrically connected to the mounting base 55 and is fixed to the mounting base 55. Further, the sensor element 1 is supported so as to be vibratably by forming a gap between the sensor element 1 and the bottom surface of the recess 55r by the thickness of the bump 59 or the like.

The mounting base 55 has a plurality of (for example, 4 or more) terminals 55c (fig. 2) located on the lower surface of the insulating base 55 a. The plurality of terminals 55c are bonded to a pad of a circuit board, not shown, via a conductive bump, not shown, for example, to facilitate mounting of the sensor 51. The plurality of terminals 55c are electrically connected to the plurality of pads 55b via, for example, unillustrated wirings of the mounting base 55.

As described above, the sensor 51 may be provided with an IC, unlike the illustrated example. In this case, for example, the sensor element 1 and the IC may be electrically connected through the wiring of the mounting substrate 55, and the IC and the terminal 55c may be electrically connected through the wiring of the mounting substrate 55.

(sensor element)

Fig. 3 is a perspective view showing the structure of the sensor element 1. In the figure, the conductive layer provided on the surface of the sensor element 1 is basically not illustrated.

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. An electrical signal (e.g., voltage or charge) generated by the vibration based on the coriolis force is detected to detect the angular velocity. Specifically, the following is shown.

(overall shape of piezoelectric body)

The piezoelectric body 3 is integrally formed, for example. The piezoelectric body 3 may be a single crystal or a polycrystal. Further, the material of the piezoelectric body 3 may be appropriately selected, and is, for example, crystal (SiO)₂) Lithium tantalate (LiTaO)₃) Lithium niobate (LiNbO)₃) Lead zirconate titanate (PZT), or silicon (Si).

In the piezoelectric body 3, an electrical axis or a polarization axis (hereinafter, both may be represented and only the polarization axis is referred to) is set so as to coincide with the x axis. The polarization axis may be tilted within a specified range (e.g., within 15 °) relative to the x-axis. Further, in the case where the piezoelectric body 3 is a single crystal, the mechanical axis as well as the optical axis may be set to an appropriate direction. For example, the mechanical axis is set to the y-axis direction, and the optical axis is set to the z-axis direction.

The piezoelectric body 3 is, for example, fixed in thickness (z-axis direction) as a whole. 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. The piezoelectric body 3 is formed in a line-symmetrical shape with respect to a symmetry axis, not shown, which is substantially parallel to the x-axis, for example. Among them, the shape of the piezoelectric body 3 due to anisotropy with respect to etching, for example, is not necessarily line-symmetric in a detailed portion due to the presence of irregularities for reducing the possibility of short-circuiting of wirings, and the like.

The piezoelectric body 3 has: two units 5(5A and 5B) arranged in line symmetry with an unillustrated symmetry axis parallel to the x-axis interposed therebetween, and a support portion 7 that supports the two units 5. Unlike the illustrated example, only one unit 5 may be provided (the piezoelectric body may be formed to have a shape symmetrical with respect to a symmetry axis parallel to the x-axis instead of a line). In the illustrated example, since the piezoelectric body 3 includes two cells 5, the detection sensitivity can be improved by adding the detection signals generated by the two cells, for example.

Each unit 5 has, for example: a frame portion 9 constituting the opening 9a, and a holding portion 11 extending from the frame portion 9 to the outside thereof. Each unit 5 includes drive arms 13(13A to 13D) and detection arms 15(15A and 15B) extending from the frame 9 to the inner side thereof. The support portion 7 includes, for example: a connecting portion 17 connected to the side opposite to the frame portion 9 side of the holding portion 11, and a pair of mounting portions 19 supporting both ends of the connecting portion 17.

The drive arm 13 is a portion that is excited by application of a voltage (electric field). The detection arm 15 vibrates by the coriolis force and generates an electric signal according to the angular velocity. The frame 9 is a portion that contributes to support of the driving arm 13 and the detection arm 15 and transmission of vibration from the driving arm 13 to the detection arm 15. The holding portion 11 is a portion that contributes to supporting the frame portion 9. The support portion 7 is a portion that helps support the holding portion 11 and helps to mount the sensor element 1 to the mounting base 55.

The frame portion 9 includes, for example: a base portion 9b and an opposing portion 9c facing each other with the opening 9a therebetween, and a pair of side portions 9d connecting both ends thereof. The base 9b, the (at least) pair of driving arms 13, and the detection arm 15 directly serve as a part for detecting the angular velocity. The structure of this portion and an electrode to be described later provided in this portion may be referred to in patent document 1 or the like, and a description of the detailed portion may be omitted in this embodiment. The portions (9c and 9d) of the frame 9 other than the base portion 9b support both ends of the base portion 9b.

(base, drive arm and detection arm)

The base portion 9b is, for example, a long strip shape having the x-axis direction as the longitudinal direction as a whole, and is bridged between the pair of side portions 9 d. In other words, both ends of the base portion 9b become supported portions supported by the pair of side portions 9 d. The base portion 9b can be flexed like a beam supported at both ends in a plan view.

In the illustrated example, the base portion 9b is formed in a shape in which the entire portion linearly extends in the x-axis direction. The base portion 9b may have other shapes. For example, the base portion 9b may have a bent portion at both ends. In this case, the base portion 9b is easily bent because the entire length of the base portion 9b is increased. The shape of the cross section (yz section) of the base portion 9b may be set as appropriate, and is rectangular in the illustrated example. The shape and size of the cross section of the base portion 9b may or may not be constant in the longitudinal direction of the base portion 9b (the illustrated example).

Various sizes of the base portion 9b may be set as appropriate. For example, one of the width (y-axis direction) and the thickness (z-axis direction) of the base portion 9b may be larger than the other. Further, for example, since it is predetermined that the base portion 9b is deflected in a plan view, the width of the base portion 9b can be relatively small. For example, the width of the base portion 9b may be set smaller than the width (x-axis direction) of the holding portion 11. Further, for example, the length and width of the base portion 9b may be adjusted to: the natural frequency of the flexure in plan view is close to the natural frequency of the drive arm 13 (in the direction of excitation by voltage application) and/or the natural frequency of the detection arm 15 (in the direction of vibration by coriolis force).

The drive arm 13 extends in the y-axis direction from the base 9b, and its tip end serves as a free end. Therefore, the driving arm 13 can be deflected like a cantilever beam. The pair of drive arms 13(13A and 13B, or 13C and 13D) in each unit 5 extend in parallel (for example, parallel) to each other at positions separated from each other in the x-axis direction. The pair of driving arms 13 are provided at positions that are line-symmetrical with respect to an unillustrated symmetry axis (see the detection arm 15) passing through the center of the base 9b and parallel to the y axis, for example.

As will be described later (fig. 5 (a) and 5 (b)), the pair of drive arms 13 are intended to deflect (vibrate) the base portion 9b in a plan view by excitation in the x-axis direction. Therefore, for example, the positions of the pair of drive arms 13 in the x-axis direction with respect to the base 9b can be appropriately set so that the base 9b is largely deflected by the vibration of the pair of drive arms 13. For example, when the length of the base portion 9b in the x-axis direction is divided into three equal parts, the pair of driving arms 13 are located in the regions on both sides.

The specific shape and the like of the drive arm 13 can be set as appropriate. For example, the driving arm 13 is formed in a long rectangular parallelepiped shape. That is, the cross section (xz section) is rectangular in shape. Although not particularly shown, the drive arm 13 may be in a hammer shape having a width (x-axis direction) that is wider at a distal end side portion. The pair of driving arms 13 in each unit 5 are, for example, substantially in line symmetry with each other in shape and size. Therefore, the vibration characteristics of both are equal to each other. However, for example, the shape of the cross section (for example, a cut in a rectangle) may be adjusted to reduce unnecessary vibration, and the shape of the pair of drive arms 13 may not be strictly line-symmetrical.

The drive arm 13 is excited in the x-axis direction as described later. Therefore, when the width (x-axis direction) of the driving arm 13 is increased, the natural frequency in the excitation direction (x-axis direction) is increased. Further, when the length (mass in other points of view) of the driving arm 13 is increased, the natural frequency in the excitation direction is lowered. Various dimensions of the drive arm 13 may be set, for example, such that the natural frequency of the drive arm 13 in the excitation direction is close to the intended frequency.

The detection arm 15 extends from the base 9b in the y-axis direction, and its leading end serves as a free end. Therefore, the detection arm 15 can be deflected like a cantilever beam. The detection arm 15 extends between the pair of drive arms 13, and is arranged (e.g., parallel) to the pair of drive arms 13. The detection arm 15 is located, for example, at the center of the base 9b in the x-axis direction and/or at the center between the pair of drive arms 13.

The specific shape and the like of the detection arm 15 can be set as appropriate. For example, the detection arm 15 is formed in a long rectangular parallelepiped shape. That is, the cross section (xz section) is rectangular in shape. The detection arm 15 may have a hammer shape whose width (x-axis direction) is widened at a distal end side portion.

As will be described later, in the present embodiment, the detection arm 15 vibrates in the x-axis direction by the coriolis force. Therefore, when the width (x-axis direction) of the detection arm 15 is increased, the natural frequency in the vibration direction (x-axis direction) is increased. Further, when the length (mass in other points of view) of the detection arm 15 is increased, the natural frequency in the vibration direction is lowered. The various dimensions of the detection arm 15 may be set such that the natural frequency of the detection arm 15 in the vibration direction is close to the natural frequency of the drive arm 13 in the excitation direction, for example. The length of the detection arm 15 is equal to the length of the drive arm 13, for example. However, the two may be different.

(frame)

The frame 9 may have any suitable shape and size as long as it includes the base 9b as a part of the periphery of the opening 9a. In the illustrated example, the frame portion 9 (the opening 9a in other aspects) is rectangular in a plan view (viewed in the z-axis direction), and the base portion 9b, the opposing portion 9c, and the pair of side portions 9d are configured by 4 sides thereof. The frame portion 9 may have a quadrangular shape other than a rectangular shape (e.g., a trapezoidal shape), a polygonal shape other than a rectangular shape (e.g., a triangular shape, a pentagonal shape, or a hexagonal shape), or a shape including a curved portion. When the frame portion 9 has the triangular shape, for example, the base portion 9b forms 1 side, and the opposing portion 9c forms one corner portion. As understood from the above description, the base portion 9b, the facing portion 9c, and the side portion 9d are not necessarily clearly distinguishable. Further, although the opposed portion 9c is also based on the definition of the end portion of the opposed portion 9c, it may not have a length in the x-axis direction unlike the base portion 9b.

In the frame portion 9 (the opening 9a in other aspects), one of the diameter in the x-axis direction and the diameter in the y-axis direction may be larger than the other. These dimensions may be set, for example, such that the shapes and dimensions of the base 9b, the driving arm 13, and the detection arm 15 are set according to a desired frequency, and then the driving arm 13 and the detection arm 15 are set to such a size that the frame 9 (the portion other than the base 9 b) does not come into contact with the vibration for detecting the angular velocity. The size of the frame 9 may be set so that the drive arm 13 or the detection arm 15 is in contact with the frame 9 (the portion other than the base portion 9 b) or not in contact with the sensor 51 when an impact having low operational relevance to intentionally detecting an angular velocity is applied to the sensor.

The shape and size of each portion (9c and 9d) other than the base portion 9b of the frame portion 9 can be set as appropriate. In the illustrated example, each portion has a long rectangular parallelepiped shape. That is, the shape of the cross section (yz section) of the facing portion 9c and the shape of the cross section (xz section) of the side portion 9d are rectangular. The shape and size of the cross section are constant in the longitudinal direction of the opposing portion 9c and the lateral portion 9d, respectively. Unlike the illustrated example, the base portion 9b may be easily bent by forming a narrow portion in a part of the side portion 9 d. The width (y-axis direction) of the opposed portion 9c and the width (x-axis direction) of the side portion 9d may be the same as (in the illustrated example) the width (y-axis direction) of the base portion 9b or may be different from each other. The widths of the facing portion 9c and the side portion 9d may be smaller than the width (x-axis direction) of the holding portion 11 (example shown), or may be the same or larger.

(holding part)

The frame 9 is supported only by the holding portion 11. That is, the frame 9 is supported by the support portion 7 via one point support by the holding portion 11. The holding portion 11 may be coupled to any position of the frame portion 9 other than the base portion 9b, for example, to the opposing portion 9c, or more specifically, to a central position in the x-axis direction of the opposing portion 9c.

The specific shape and size of the holding portion 11 can be set as appropriate. In the illustrated example, the holding portion 11 linearly extends (protrudes) in the y-axis direction, and the holding portion 11 has a rectangular parallelepiped shape. The size of the holding portion 11 may be appropriately set as long as it can support the frame 9 and the arms (13 and 15) extending from the frame 9, for example. For example, the width (x-axis direction) of the holding portion 11 is set smaller than the length (x-axis direction) of the base portion 9b, the length (x-axis direction) of the opposing portion 9c, and/or the maximum diameter of the frame portion 9 in the x-axis direction. For example, the width of the holding portion 11 may be set to be 1/3 or less, 1/4 or less, or 1/5 or less of the length of the base portion 9b, the length of the opposing portion 9c, and/or the maximum diameter of the frame portion 9 in the x-axis direction. The width (x-axis direction) of the holding portion 11 may be smaller than the length (y-axis direction), may be equal to the width, or may be larger than the length (y-axis direction) (example shown in the figure).

(bearing part)

The shape and size of the support portion 7 are arbitrary. The illustrated example is merely an example. As described above, in the illustrated example, the support portion 7 includes the connection portion 17 and the pair of attachment portions 19. In another aspect, the support portion 7 has a substantially H-shape. Instead of the attachment portion 19, a frame-shaped attachment portion 19 surrounding the two units 5 and the connection portion 17 may be provided.

The specific shape and size of the coupling portion 17 can be set as appropriate. In the illustrated example, the coupling portion 17 is formed in an elongated shape extending linearly in the x-axis direction, and is formed in a rectangular parallelepiped shape. The size of the coupling portion 17 may be appropriately set as long as it can support a predetermined number (two in this case) of cells 5, for example. For example, the length (x-axis direction) of the coupling portion 17 is set longer than the outer diameter of the frame portion 9 in the x-axis direction, so that the pair of mounting portions 19 can be positioned on both sides of the frame portion 9 in the x-axis direction. The width (y-axis direction) of the connecting portion 17 is set to be larger than the width of the frame portion 9 and the various arms (13 and 15), for example. The width of the coupling portion 17 may be smaller than the width of the holding portion 11, may be equal (in the illustrated example), or may be larger than the width.

The specific shape and size of the pair of mounting portions 19 can be set as appropriate. In the illustrated example, the mounting portion 19 is formed in an elongated shape extending linearly in the y-axis direction, and is also formed in a rectangular parallelepiped shape. The size of the mounting portion 19 may be appropriately set as long as it can support the connection portion 17 and a predetermined number (two in this case) of the units 5, for example. The length (y-axis direction) of the mounting portion 19 may be a length in which the end of the mounting portion 19 is in a range closer to the connection portion 17 than the base portion 9b, or may be a length longer than the length. The width (x-axis direction) of the mounting portion 19 may be larger than the width (y-axis direction) of the coupling portion 17 (example shown in the figure), or may be equal to or smaller than the width.

(conductor of sensor element)

Fig. 4 (a) is an enlarged perspective view of a part of the sensor element 1. More specifically, a part of the cell 5B is shown. Fig. 4 (b) is a sectional view taken along line IVb-IVb of fig. 4 (a). Although the cell 5B is illustrated here, the same applies to the cell 5A except that the sign of the y-axis is reversed.

The sensor element 1 has a conductor located on the piezoelectric body 3. The conductors are, for example, excitation electrodes 21(21A and 21B) for applying a voltage to the drive arm 13, detection electrodes 23(23A and 23B) for extracting a signal generated in the detection arm 15, terminals 27 (fig. 3) for mounting the sensor element 1 on the mounting substrate 55, and a wiring 25 for connecting these. The conductor may be provided with a reference potential and have a pattern that functions as a shield. The various conductors include, for example, a conductor layer formed on the surface of the piezoelectric body 3. The material of the conductor layer is, for example, a metal such as Cu or Al.

The reference symbol A, B for the excitation electrode 21 and the detection electrode 23 is attached based on the orthogonal coordinate system xyz. Therefore, as will be described later, the excitation electrode 21A of one drive arm 13 and the excitation electrode 21A of the other drive arm 13 are not limited to the same potential. The same applies to the excitation electrode 21B. The same applies to the detection electrodes 23A and 23B in the embodiment in which the plurality of detection arms 15 are provided as in the present embodiment.

(excitation electrode)

The excitation electrodes 21A are provided on the upper surface and the lower surface (a pair of surfaces facing both sides in the z-axis direction) of each drive arm 13. The excitation electrodes 21B are provided on a pair of side surfaces (a pair of surfaces facing both sides in the x-axis direction) of each of the drive arms 13. In any of the cells 5A and 5B, (even if the drive arm 13 extends on either of the + y side and the-y side), it is assumed that reference symbol a of the excitation electrode 21 corresponds to the upper surface and the lower surface, and reference symbol B of the excitation electrode 21 corresponds to the side surface.

The excitation electrodes 21 are formed on the respective upper, lower, left, and right surfaces of the respective drive arms 13 so as to cover most of the respective surfaces, for example. At least one of the excitation electrodes 21A and 21B (the excitation electrode 21A in the present embodiment) is formed to be smaller than each surface in the width direction so as not to be short-circuited with each other. Further, a part of the base side and the tip side of the driving arm 13 may be a non-arrangement position of the excitation electrode 21.

In each drive arm 13, the two excitation electrodes 21A are set to the same potential as each other. In each of the drive arms 13, the two excitation electrodes 21B are set to the same potential. The excitation electrodes 21 which should be set to the same potential are connected to each other, for example, by a wiring 25.

When a voltage is applied between the excitation electrodes 21A and 21B, an electric field directed from the upper surface toward the pair of side surfaces (both sides in the x-axis direction) and an electric field directed from the lower surface toward the pair of side surfaces are generated in the drive arm 13, for example. On the other hand, the polarization axis coincides with the x-axis direction. Therefore, focusing on the x-axis direction component of the electric field, the direction of the electric field coincides with the direction of the polarization axis in one side portion of the drive arm 13 in the x-axis direction, and is opposite to the direction of the polarization axis in the other side portion.

As a result, one portion of the driving arm 13 in the x-axis direction contracts in the y-axis direction, and the other portion extends in the y-axis direction. The drive arm 13 is bent toward one side in the x-axis direction like a bimetal. When the voltages applied to the excitation electrodes 21A and 21B are opposite, the driving arm 13 bends in the opposite direction. By this principle, when an ac voltage is applied to the excitation electrodes 21A and 21B, the drive arm 13 vibrates in the x-axis direction.

Although not particularly shown, one or more grooves extending in the longitudinal direction of the drive arm 13 (the grooves may be formed by arranging a plurality of concave portions in the longitudinal direction of the drive arm 13) may be provided on the upper surface and/or the lower surface of the drive arm 13, and the excitation electrodes 21A may be provided over the grooves. In this case, the excitation electrode 21A and the excitation electrode 21B face 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 13 of each unit 5, the excitation electrode 21A of one drive arm 13 and the excitation electrode 21B of the other drive arm 13 are set to the same potential. The excitation electrodes 21 which should be set to the same potential are connected to each other, for example, by a wiring 25.

In this connection, when an ac voltage is applied between the excitation electrode 21A and the excitation electrode 21B, voltages having mutually opposite phases are applied to the pair of drive arms 13. As a result, the pair of drive arms 13 vibrate to deflect in opposite directions to each other in the x-axis direction.

Focusing on the two units 5, for example, between the two drive arms 13 (two of 13A and 13C, or two of 13B and 13D) located on the same side in the x-axis direction with respect to the detection arm 15(15A and 15B), the excitation electrodes 21A are set to the same potential and the excitation electrodes 21B are set to the same potential. The excitation electrodes 21 which should be set to the same potential are connected to each other, for example, by a wiring 25.

In this connection relationship, when an ac voltage is applied between the excitation electrode 21A and the excitation electrode 21B, voltages of the same phase are applied to the two drive arms 13 located on the same side in the x-axis direction. As a result, the two drive arms 13 vibrate so as to deflect in the same direction in the x-axis direction.

Unlike the present embodiment, the excitation electrode 21A and the excitation electrode 21B may be set to the same potential between the two drive arms 13 located on the same side in the x-axis direction with respect to the detection arm 15(15A and 15B).

(detection electrode)

The detection electrode 23 has the same configuration as the excitation electrode 21 in the present embodiment. That is, the detection electrodes 23A are provided on the upper surface and the lower surface (a pair of surfaces facing both sides in the z-axis direction) of the detection arm 15, respectively. The detection electrodes 23B are provided on a pair of side surfaces (a pair of surfaces facing both sides in the x-axis direction) of the detection arm 15, respectively. The two detection electrodes 23A are connected to each other, and further, the two detection electrodes 23B are connected to each other. The connection is made, for example, by a wiring 25.

Similarly to the excitation electrode 21, in the detection electrode 23, the reference symbol a corresponds to the upper surface and the lower surface, and the reference symbol B corresponds to the side surface, regardless of which of the + y side and the-y side the detection arm 15 extends. The above description of the width and arrangement position of the driving arm 13 of the excitation electrode 21 can be applied to the width and arrangement position of the detection arm 15 of the detection electrode 23. Further, in the detection arm 15, a groove may be formed on the upper surface and/or the lower surface.

When the detection arm 15 is flexed in the x-axis direction, a voltage is generated between the detection electrode 23A and the detection electrode 23B by a principle opposite to the excitation of the driving arm 13. In other words, the detection electrodes 23A and 17B take out charges (potential or signal in other points of view) different in positive and negative (polarity) from each other from the detection arm 15. When the detection arm 15 vibrates in the x-axis direction, the voltage applied to the detection electrode 23 is detected as an ac voltage.

In each of the two cells 5 (two detection arms 15), the detection electrode 23A and the detection electrode 23B are connected. The connection is made, for example, by a wiring 25. In this connection relationship, when the two detection arms 15 are deflected to the opposite sides of each other in the x-axis direction, signals extracted from the two detection arms are added.

As described above, in the two units 5, the excitation electrodes 21A and 21B may be set to the same potential in the two drive arms 13(13A and 13C, or 13B and 13D) located on the same side in the x-axis direction, unlike the present embodiment. In this case, between the two units 5 (two detection arms 15), the detection electrodes 23A are connected to each other, and the detection electrodes 23B are connected to each other.

(terminal)

At least 4 terminals 27 (fig. 3) are provided, for example, on the lower surfaces of the pair of mounting portions 19. The terminal 27 faces the pad 55b of the mounting base 55 shown in fig. 2, and is joined to the pad 55b by a bump 59. Thus, as described above, the sensor element 1 and the mounting substrate 55 are electrically connected, and the sensor element 1 (the piezoelectric body 3) is supported in a state in which the drive arm 13 and the detection arm 15 can vibrate. The 4 terminals 27 are provided at both ends of the pair of mounting portions 19, for example.

(Wiring)

As understood from the above description of the excitation electrodes 21, the case where the plurality of excitation electrodes 21 are connected to each other by the plurality of wires 25 is included. As understood from the above description of the detection electrodes 23, the case where the plurality of wires 25 connect the plurality of detection electrodes 23 to each other is included. The excitation electrodes 21 are divided into 2 groups having different potentials and the detection electrodes 23 are divided into 2 groups having different potentials by connection through the wirings 25. The case where the 4 groups of electrodes are individually connected to the 4 terminals 27 by the plurality of wirings 25 is included.

The plurality of wires 25 are appropriately arranged on the upper surface, the lower surface, and/or the side surfaces of various portions (7, 9, 13, and 15) of the piezoelectric body 3, and the above-described connection can be achieved without short-circuiting each other so that the entire portion is provided on the surface of the piezoelectric body 3. Here, the three-dimensional wiring portion can be formed by overlapping an insulating layer on a part of the wiring 25 on the piezoelectric body 3 and providing another wiring 25 on the insulating layer.

(drive Circuit and detection Circuit)

As shown in fig. 4 (b), the sensor element 1 is electrically connected to the drive circuit 103 and the detection circuit 105. The drive circuit 103 is a circuit for exciting the sensor element 1. The detection circuit 105 is a circuit for detecting a signal corresponding to an angular velocity from the sensor element 1.

The drive circuit 103 is configured to include, for example, an oscillation circuit and an amplifier, and apply an ac voltage of a predetermined frequency between the excitation electrodes 21A and 21B via the two terminals 27. 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, detect a potential difference between the detection electrode 23A and the detection electrode 23B via the two terminals 27, and output an electric signal corresponding to a detection result thereof to an external device or the like. More specifically, for example, the potential difference is detected as an ac voltage. The detection circuit 105 outputs a signal corresponding to the amplitude of the detected ac voltage. An angular velocity is determined based on the amplitude. Further, the detection circuit 105 outputs a signal corresponding to a phase difference between the applied voltage of the drive circuit 103 and the detected electric signal. An orientation of the rotation is 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 includes, for example, a chip ic (integrated circuit). As described above, the angular velocity sensor 51 may include an electronic component mounted on the mounting substrate 55 in addition to the sensor element 1. The control circuit 107 may include, for example, electronic components mounted on the mounting substrate 55, or may include electronic components mounted on a circuit board on which the angular velocity sensor 51 is mounted. In addition to the sensor element 1, a structure including the drive circuit 103 and the detection circuit 105 can also be defined as an angular velocity sensor.

(operation of angular velocity sensor)

Fig. 5 (a) and 5 (b) are schematic plan views for explaining the excitation of the piezoelectric body 3. In both figures, the phases of the alternating voltages applied to the excitation electrodes 21 are different from each other by 180 °.

As described above, in each unit 5, the pair of drive arms 13(13A and 13B, or 13C and 13D) are excited by an alternating voltage applied thereto via the excitation electrodes 21 so that phases opposite to each other are excited to deform in directions opposite to each other in the x-axis direction.

At this time, as shown in fig. 5 (a), when the pair of drive arms 13 are flexed outward in the x-axis direction (on the side where the pair of drive arms 13 are separated from each other), the bending moment is transmitted to the base portion 9b, and the base portion 9b is flexed on the y-axis direction side. Specifically, one side in the y-axis direction is a direction from the base side to the tip side of the driving arm 13, and is a-y side in the unit 5A and a + y axis in the unit 5B. As a result of the base portion 9b being deflected to the one side in the y-axis direction, the detection arm 15 is displaced to the one side in the y-axis direction.

On the contrary, as shown in fig. 5b, when the pair of driving arms 13 are flexed inward in the x-axis direction (the side where the pair of driving arms 13 approach each other), the bending moment is transmitted to the base portion 9b, and the base portion 9b is flexed to the other side in the y-axis direction. The other side in the y-axis direction is specifically a direction from the distal end side to the proximal end side of the driving arm 13, and is the + y side in the unit 5A and the-y axis in the unit 5B. As a result of the base portion 9b being deflected to the other side in the y-axis direction, the detection arm 15 is displaced to the other side in the y-axis direction.

In each unit 5, the pair of drive arms 13 vibrate by repeating the bending outward in the x-axis direction and the bending inward in the x-axis direction, and thereby the detection arm 15 vibrates in the y-axis direction.

Focusing on the two units 5, as described above, the two drive arms 13 (two of 13A and 13C, or two of 13B and 13D) located on the same side in the x-axis direction vibrate in the same phase. In another viewpoint, the two units 5 vibrate in the same phase with respect to the deflection toward the inside in the x-axis direction and the deflection toward the outside in the x-axis direction in the pair of driving arms 13. Here, since the y-axis directions of the two units 5 are opposite to each other, the detection arms 15A and 15B vibrate in opposite phases to each other so as to be displaced to opposite sides from each other in the y-axis direction.

Fig. 6 (a) and 6 (b) are schematic plan views for explaining the vibration of the detection arm 15 due to the coriolis force. Fig. 6 (a) and 6 (b) correspond to the states of fig. 5 (a) and 5 (b). In the figure, the driving arm 13 and the base 9b are not illustrated in their modified forms.

As described with reference to fig. 5 (a) and 5 (b), the piezoelectric body 3 vibrates. In this state, when the sensor element 1 is rotated about the z axis, the detection arm 15 vibrates (displaces) in the y axis direction, and thus vibrates (deforms) in a direction (x axis direction) orthogonal to the rotation axis (z axis) and the vibration direction (y axis) by the coriolis force. The signal (e.g., voltage) generated by the deformation is extracted by the detection electrode 23 as described above. The greater the angular velocity, the greater the coriolis force (and thus the voltage of the detected signal). Thereby, the angular velocity is detected.

Further, focusing on the two units 5, the two detection arms 15 vibrate in mutually opposite phases by the flexure of the base portion 9b so as to displace to mutually opposite sides in the y-axis direction, and therefore vibrate in mutually opposite phases by the coriolis force so as to flex to mutually opposite sides in the x-axis direction. In the above-described connection relationship of the detection electrodes 23, the signals detected by the two detection arms 15 are added to each other.

As described above, in the present embodiment, the angular velocity sensor 51 includes: the sensor element 1 and a mounting base 55 supporting the sensor element 1. The sensor element 1 includes: piezoelectric body 3, a plurality of excitation electrodes 21, and a plurality of detection electrodes 23. The piezoelectric body 3 has a base portion 9b, a pair of driving arms 13, and a detection arm 15. The base 9b has the x-axis direction of the orthogonal coordinate system xyz as the longitudinal direction. The pair of drive arms 13 extend in parallel with each other in the y-axis direction from the base 9b at positions separated from each other in the x-axis direction. The detection arm 15 extends from the base 9b in the y-axis direction at the center between the pair of drive arms 13. The plurality of excitation electrodes 21 are positioned on the pair of drive arms 13 in an arrangement and connection relationship such that the pair of drive arms 13 are excited with mutually opposite phases in the x-axis direction. The plurality of detection electrodes 23 are disposed in the detection arm 15 so as to extract a signal generated by vibration of the detection arm 15 in the x-axis direction or the z-axis direction (in the present embodiment, the x-axis direction).

In the present embodiment, the piezoelectric body 3 includes the frame portion 9, the holding portion 11, and the support portion 7. The frame 9 forms an opening 9a when viewed in the z-axis direction. The frame portion 9 includes a base portion 9b and an opposing portion 9c located on the opposite side of the opening 9a from the base portion 9b as a part of the periphery of the opening 9a when viewed in the z-axis direction. The holding portion 11 extends outward of the opening 9a (e.g., in the y-axis direction) from the facing portion 9c when viewed in the z-axis direction. The supporting portion 7 is connected to the holding portion 11 on the side opposite to the facing portion 9c side, and is supported by the mounting base 55. The frame 9 is supported at one point by the holding portion 11.

Therefore, for example, the accuracy of detection of the angular velocity is improved. Specifically, for example, the following is shown. In the embodiment, the sensor element 1 is bonded to the mounting substrate 55 at a plurality of positions (positions of the terminal 27 and the land 55 b) separated from each other. At this time, the plurality of terminals 27 are forced in different directions by curing shrinkage of the bumps 59, and the support portions 7 may be deformed. In other points of view, there is a possibility that unintentional stress is applied to the support portion 7. At this time, in the present embodiment, since the frame portion 9 is supported at one point by the holding portion 11, the deformation of the support portion 7 displaces the frame portion 9, but the possibility of deformation of the frame portion 9 is reduced. In another aspect, the stress transmitted from the support portion 7 to the frame portion 9 is reduced. As a result, the influence of the stress applied to the support portion 7 on the vibration of the drive arm 13 and the detection arm 15 extending from the frame portion 9 is reduced. Therefore, variations in detection accuracy due to variations in mounting of the sensor element 1 to the mounting base 55 are reduced.

Note that fig. 5 (a) and 5 (b) focus on the deflection of the base portion 9b. The frame portion 9 can be flexed by the vibration of the driving arm 13 at a portion other than the base portion 9b, that is, a portion not connected to the holding portion 11 (for example, the pair of side portions 9 d). In other words, the frame 9 is configured to support one point between the base 9b and the support 7, but serves to facilitate the bending of the base 9b. This increases the amplitude of the detection arm 15 in the y-axis direction, for example, and can improve the detection sensitivity.

In the present embodiment, the pair of driving arms 13 extend from the base portion 9b into the opening 9a. Further, the detection arm 15 extends from the base portion 9b into the opening 9a.

In this case, for example, the opening 9a generated when the frame 9 is formed for one-point holding can be effectively used as the arrangement region of the driving arm 13 and the detection arm 15. As a result, for example, the sensor element 1 can be easily downsized. The driving arm 13 and the detection arm 15 (and the conductors located in these arms) are located in the opening 9a, and are protected from external contact by the frame 9, for example. As a result, for example, in the work of carrying the sensor element 1 and mounting the sensor element 1 to the mounting base 55, the possibility of occurrence of a flaw in the sensor element 1 is reduced, and the possibility of deterioration of the detection accuracy is reduced. Further, for example, when an impact having a low correlation with the angular velocity of the detection target is applied to the sensor element 1 and there is a possibility that the driving arm 13 is excessively deformed, the frame portion 9 can function as a stopper that comes into contact with the driving arm 13 and reduces the possibility of the excessively deformed driving arm.

In the present embodiment, all the drive arms 13 and all the detection arms 15 extending from the frame 9 extend into the opening 9a.

In this case, for example, the above-described effect of downsizing and the effect of protecting the driving arm 13 and the detection arm 15 by the frame 9 are improved.

In the present embodiment, the holding portion 11 extends from the base portion 9b to the outside of the opening 9a and is coupled to the support portion 7. The piezoelectric body 3 has two cells 5. Each unit 5 includes a holding portion 11, a frame portion 9, a pair of driving arms 13, and a detection arm 15. The two units 5 have the holding portions 11 facing each other on the side extending from the frame portion 9.

In this case, for example, if the support portion 7 has a portion located between the two units 5, it is possible to support the two units 5. In other words, the portion (the coupling portion 17) of the support portion 7 coupled to the holding portion 11 can be shared by the two units 5. As a result, for example, the sensor element 1 can be easily downsized. Further, by providing two units 5 and exciting both units in the same phase, the acceleration applied to the sensor element 1 by the vibration of the base portion 9b and the detection arm 15 in the y-axis direction can be at least partially cancelled out by the two units 5. As a result, for example, unnecessary vibration that vibrates the entire sensor element 1 in the y-axis direction can be reduced.

[ 2 nd embodiment ]

Fig. 7 (a) is a perspective view similar to fig. 4 (a) showing a part of the sensor element 201 according to embodiment 2 in an enlarged manner. Fig. 7 (b) is a view similar to fig. 4 (b) showing the angular velocity sensor 251 according to embodiment 2, and includes a cross-sectional view corresponding to a line VIIb-VIIb in fig. 7 (a).

The angular velocity sensor 251 according to embodiment 2 vibrates the pair of drive arms 13 in the x-axis direction, thereby bending (vibrating) the base 9b and further displacing (vibrating) the detection arm 15 in the y-axis direction, similarly to the angular velocity sensor 51 according to embodiment 1. Then, the coriolis force is directly applied to the detection arm 15. In which the rotation around the z-axis is detected with respect to the angular velocity sensor 51, and the angular velocity sensor 251 detects the rotation around the x-axis. Specifically, the following is shown.

The sensor element 201 includes the piezoelectric body 3, a plurality of excitation electrodes 21, a plurality of detection electrodes 223(223A and 223B), a plurality of terminals 27 (fig. 3), and a plurality of wirings 25. These elements can be basically the same as those of the sensor element 1 according to embodiment 1, except for the arrangement and connection relationship of the plurality of detection electrodes 223. Fig. 1 to 3 can be regarded as diagrams showing the sensor element 201.

In the present embodiment, unlike embodiment 1, the detection arm 15 is intended to vibrate in the z-axis direction by the coriolis force. Based on this difference, various sizes may be different from embodiment 1.

The detection electrode 223A is provided in the detection arm 15 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) of 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) of the surface facing the positive side in the x-axis direction. The detection electrode 223B is provided in the detection arm 15 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) of 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) of the surface facing the positive side in the x-axis direction.

On each side surface of the detection arm 15, the detection electrodes 223A and 223B extend along the detection arm 15 with an appropriate interval so as not to short-circuit each other. In each detection arm 15, the two detection electrodes 223A are connected to each other by, for example, a wiring 25. In each detection arm 15, the two detection electrodes 223B are connected to each other by, for example, a wiring 25.

In the arrangement and connection relationship of the detection electrodes 223, when the detection arm 15 is flexed in the z-axis direction, an electric field parallel to the z-axis direction, for example, is generated. That is, a voltage is generated between the detection electrode 223A and the detection electrode 223B on each side surface of the detection arm 15. The direction of the electric field is determined by the direction of the polarization axis or the direction of the bend (positive or negative side in the z-axis direction), and the positive side portion and the negative side portion in the x-axis direction are opposite to each other. The voltage (electric field) is output to the detection electrode 223A and the detection electrode 223B. When the detection arm 15 vibrates in the z-axis direction, the voltage is detected as an alternating voltage. As described above, the electric field may dominate the electric field parallel to the z-axis direction, or the proportion of the electric field parallel to the x-axis direction and oriented in the opposite direction to the positive side portion and the negative side portion in the z-axis direction may be large. In either case, a voltage corresponding to the deflection of the detection arm 15 in the z-axis direction is generated between the detection electrode 223A and the detection electrode 223B.

Although not particularly shown, the detection arm 15 may be formed with one or more through grooves (slits) that extend in the longitudinal direction of the detection arm 15 from the upper surface to the lower surface. The detection electrodes 223A and 223B may be arranged and connected in a plurality of elongated portions divided by the through grooves, as in the detection arm 15 of the illustrated example. In this case, the plurality of detection electrodes 223 have a larger area as a whole than those provided only on the outer side surface of the detection arm 15. As a result, the electric charges generated in the detection arm 15 can be efficiently extracted as an electric signal.

In each of the two cells 5 (two detection arms 15), the detection electrode 223A and the detection electrode 223B are connected. The connection is made, for example, by a wiring 25. In this connection relationship, when the two detection arms 15 are flexed toward the opposite sides of each other in the z-axis direction, signals extracted from the two detection arms are added.

As described in the description of embodiment 1, when focusing on two units 5, the excitation electrode 21A and the excitation electrode 21B may be set to the same potential between the two drive arms 13 (two of 13A and 13C, or two of 13B and 13D) located on the same side in the x-axis direction, unlike embodiment 1 (and this embodiment). In this case, in the two detection arms 15, the detection electrodes 223A are connected to each other, and the detection electrodes 223B are connected to each other.

As described above, the plurality of detection electrodes 223 are divided into 2 groups from the viewpoint of potential. The 2 sets of detection electrodes 223 are connected to the two terminals 27 via the wiring 25, as in embodiment 1.

(operation of angular velocity sensor)

The excitation of the piezoelectric body 3 in embodiment 2 is similar to that in embodiment 1. Fig. 5 (a) and 5 (b) can be regarded as views showing the state of excitation of the piezoelectric body 3 in embodiment 2. Therefore, for example, in each unit 5, the pair of drive arms 13 vibrate in the x-axis direction while approaching or separating from each other, and the detection arm 15 displaces (vibrates) in the y-axis direction.

Fig. 8 (a) and 8 (b) are schematic perspective views for explaining the vibration of the detection arm 15 due to the coriolis force. Fig. 8 (a) and 8 (b) correspond to the excitation states of fig. 5 (a) and 5 (b).

As described with reference to fig. 5 (a) and 5 (b), a state in which the piezoelectric body 3 vibrates is considered. In this state, when the sensor element 201 is rotated about the x axis, the detection arm 15 vibrates (displaces) in the y axis direction, and thus vibrates (deforms) in a direction (z axis direction) orthogonal to the rotation axis (x axis) and the vibration direction (y axis) by the coriolis force. The signal (voltage) generated by the deformation is extracted by the detection electrode 223 as described above. The greater the angular velocity, the greater the coriolis force (and thus the voltage of the detected signal). Thereby, the angular velocity is detected.

In addition, focusing on the two units 5, the two detection arms 15 vibrate in mutually opposite phases by the flexure of the base portion 9b so as to be displaced on mutually opposite sides in the y-axis direction, and therefore vibrate in mutually opposite phases by the coriolis force so as to be flexed on mutually opposite sides in the z-axis direction. In the connection relationship of the detection electrodes 223, the signals detected by the two detection arms 15 are added to each other.

[ embodiment 3 ]

Fig. 9 is a perspective view showing a sensor element 301 according to embodiment 3. In the figure, the piezoelectric body 3 is shown as in fig. 3, and the excitation electrode 21 and the detection electrodes 23 and 223 are also shown.

In one of the two units 5 of the sensor element 301 (here, the unit SA), the detection electrode 23 is provided in an arrangement and connection relationship capable of detecting the vibration of the detection arm 15(15A) in the x-axis direction, as in embodiment 1. On the other hand, in the other of the two cells 5 (in this case, the cell 5B), the detection electrode 223 is provided in an arrangement and connection relationship capable of detecting the z-axis direction vibration of the detection arm 15(15B) as in embodiment 2. That is, the sensor element 301 is configured to: a sensor element for a multi-axis angular velocity sensor for detecting an angular velocity around the z-axis by the cell 5A and an angular velocity around the x-axis by the cell 5B.

In the two units 5, the vibrations of the drive arms 13 may have the same frequency and the same phase, for example, as in embodiment 1. That is, between the two cells 5, the excitation electrodes 21A may be set to the same potential as each other, and the excitation electrodes 21B may be set to the same potential as each other. On the other hand, since the detection electrodes 23 and 223 output signals corresponding to different angular velocities, they are not connected to each other. In addition, 6 terminals 27 are provided so as to correspond to 6 excitation electrodes 21 and detection electrodes 23 and 223 in terms of potential. The position thereof may be set to an appropriate position of the support portion 7 (mounting portion 19).

[ 4 th embodiment ]

Fig. 10 is a plan view showing a main part of a sensor element 401 according to embodiment 4. In the figure, a part of the piezoelectric body 403 of the sensor element 401 is shown.

The piezoelectric body 403 includes a holding portion 11 and a frame portion 409 supported at one point by the holding portion 11, as in embodiment 1. Here, only one unit 405 is shown, but two units 405 may be provided as in embodiment 1, and the configuration of the support portion that supports two units 405 may be the same as, for example, the configuration of the support portion 7 in embodiment 1.

From the frame portion 409, as in embodiment 1, the driving arm 13 and the detection arm 15 extend from a base portion 409b located on the opposite side of the holding portion 11 with an opening 409a interposed therebetween. In the present embodiment, unlike embodiment 1, at least 1 driving arm 413 and at least 1 detecting arm 415 extend from the facing portion 409c on the holding portion 11 side. That is, the sensor element 401 includes a 1 st sensor portion 406A located on the base 409B side and a 2 nd sensor portion 406B located on the opposing portion 409c side.

The vibration mode related to the detection of the angular velocity of the 1 st sensor unit 406A is the same as that of embodiment 1 or embodiment 2. The vibration mode related to the detection of the angular velocity of the 2 nd sensor unit 406B is different from that of the 1 st sensor unit 406A. In the vibration mode of the 2 nd sensor unit 406B, the deflection of the facing portion 409c for displacing the detection arm 415 in the y-axis direction is not required. Therefore, as in the illustrated example, the facing portion 409c can be increased in width (y-axis direction) compared to the base portion 409 b.

The rotation axis for detecting the angular velocity by the 2 nd sensor unit 406B may be the same as or different from the rotation axis for detecting the angular velocity by the 1 st sensor unit 406A. For example, the rotation axis in which the 2 nd sensor unit 406B detects the angular velocity is the y-axis. As understood from the foregoing description, the 1 st sensor portion 406A can detect an angular velocity around the z-axis (embodiment 1) or an angular velocity around the x-axis (embodiment 2). Therefore, in the case where the 2 nd sensor portion 406B detects an angular velocity around the y-axis, the sensor element 401 constitutes a multi-axis angular velocity sensor that detects an angular velocity around the z-axis and an angular velocity around the y-axis, or a multi-axis angular velocity sensor that detects an angular velocity around the x-axis and an angular velocity around the y-axis.

When the 2 nd sensor unit 406 detects an angular velocity around the y-axis, the configuration thereof includes a known configuration, and various configurations can be adopted. In the following, 4 examples are briefly explained.

In the illustrated example, the 2 nd sensor portion 406 has the same structure as that of the angular velocity sensor described in JP 2015-141182 a. The content of this publication can be referred to by reference (Incorporation by reference).

The 2 nd sensor unit 406 of the illustrated example includes: a pair of driving arms 413 arranged in line symmetry with respect to a symmetry axis (not shown) parallel to the y-axis and passing through the center of the opposing portion 409c, and a pair of detection arms 415 arranged in line symmetry with respect to the symmetry axis on the outer side (or inner side) thereof.

The pair of drive arms 413 are excited in the x-axis direction with mutually opposite phases, similarly to the pair of drive arms 13 of embodiment 1. In balance with this vibration, the pair of detection arms 415 also vibrate in opposite phases to each other in the x-axis direction. When the 2 nd sensor unit 406 is rotated about the y axis, the pair of detection arms 415 vibrate in opposite phases to each other in the z axis direction by the coriolis force. Thereby, the angular velocity is detected.

As understood from the above operation, a plurality of excitation electrodes 21 are provided on the pair of drive arms 413 in the same arrangement and connection relationship as those of embodiment 1. In addition, a plurality of detection electrodes 223 are provided in each detection arm 415 in the same arrangement and connection relationship as in embodiment 2. The detection electrode 223A and the detection electrode 223B are connected to the pair of detection arms 415.

Note that the configuration shown as a sensor for detecting an angular velocity around the y-axis in fig. 12 and 13 of patent document 1 can also be applied to the 2 nd sensor unit 406.

In the 2 nd sensor unit 406 using the sensor of the above-mentioned document, there are provided (at least) a pair of driving arms 413 and a pair of detection arms 415 which are arranged line-symmetrically with respect to a symmetry axis (not shown) which is parallel to the y-axis and passes through the center of the opposing portion 409 c. The pair of driving arms 413 extend from the facing portion 409c to one side in the y-axis direction, and the pair of driving arms 413 extend from the facing portion 409c to the other side in the y-axis direction.

The pair of drive arms 413 are excited in the x-axis direction with mutually opposite phases, similarly to the pair of drive arms 13 of embodiment 1. When the 2 nd sensor unit 406 is rotated about the y axis, the pair of drive arms 413 vibrate in opposite phases to each other in the z axis direction by the coriolis force. In balance with this vibration, the pair of detection arms 415 also vibrate in opposite phases to each other in the z-axis direction. Thereby, the angular velocity is detected.

As understood from the above operation, a plurality of excitation electrodes 21 are provided on the pair of drive arms 413 in the same arrangement and connection relationship as those of embodiment 1. In addition, a plurality of detection electrodes 223 are provided in each detection arm 415 in the same arrangement and connection relationship as in embodiment 2. The detection electrode 223A and the detection electrode 223B are connected to the pair of detection arms 415.

Further, the sensor disclosed in JP 2015-99130 a can be applied to the 2 nd sensor portion 406. The content of this publication can be referred to by reference (Incorporation by reference).

In the 2 nd sensor unit 406 using the sensor of the above-mentioned publication, there are provided (at least) a pair of driving arms 413 arranged line-symmetrically with respect to a symmetry axis (not shown) parallel to the y-axis and passing through the center of the opposing portion 409c, and a detection arm 415 extending on the symmetry axis. The pair of driving arms 413 and the detection arm 415 extend in parallel with each other, for example.

The pair of drive arms 413 are excited in the x-axis direction with the same phase. When the 2 nd sensor unit 406 is rotated about the y axis, the pair of drive arms 413 vibrate in the z axis direction at the same phase with each other by the coriolis force. In balance with this vibration, the detection arm 415 also vibrates in the z-axis direction. Thereby, the angular velocity is detected.

As understood from the above operation, a plurality of excitation electrodes 21 are provided in each drive arm 413 in the same arrangement and connection relationship as those in embodiment 1. In the pair of driving arms 413, the excitation electrodes 21A are connected to each other, and the excitation electrodes 21B are connected to each other. Further, a plurality of detection electrodes 223 are provided in the detection arm 415 in the same arrangement and connection relationship as in embodiment 2.

A so-called tuning fork type sensor can be applied to the 2 nd sensor unit 406. In the 2 nd sensor unit 406 using a tuning-fork sensor, 1 driving arm 413 and 1 detecting arm 415 extending in parallel with each other in the y-axis direction are arranged in line symmetry with respect to an unillustrated symmetry axis parallel to the y-axis and passing through the center of the opposing portion 409 c. Drive arm 413 is energized in the x-axis direction. In balance with this vibration, the detection arm 415 also vibrates in the x-axis direction. When the 2 nd sensor unit 406 is rotated about the y axis, the detection arm 415 vibrates in the z axis direction by the coriolis force. Thereby, the angular velocity is detected. As understood from the above operation, the driving arm 413 is provided with a plurality of excitation electrodes 21 in the same arrangement and connection relationship as those of embodiment 1. Further, a plurality of detection electrodes 223 are provided in the detection arm 415 in the same arrangement and connection relationship as in embodiment 2.

As described above, in embodiment 4, piezoelectric body 403 includes, in addition to the configuration of piezoelectric body 3 of embodiment 1, the 2 nd drive arm (drive arm 413) and the 2 nd detection arm (detection arm 415). The driving arm 413 and the detection arm 415 extend from the facing portion 409c in the y-axis direction. The sensor element 401 (the 2 nd sensor portion 406B) has a plurality of excitation electrodes 21 (fig. 4) and a plurality of detection electrodes 223 (fig. 7). The plurality of excitation electrodes 21 are disposed on the driving arm 413 so as to excite the driving arm 413 in the x-axis direction. The plurality of detection electrodes 223 are disposed on the detection arm 415 in such a manner as to extract a signal generated by the vibration of the detection arm 415 in the z-axis direction.

Therefore, for example, a multi-axis angular velocity sensor can be realized by one piezoelectric body 403. For example, in the configuration in which the driving arm 413 and the detection arm 415 extend into the opening 409a of the frame 409, the length of the side portion 409d of the frame 409 can be increased by a length corresponding to the length of the driving arm 413 and the detection arm 415. The side portion 409d is increased, and the base portion 409b is easily bent, for example, so that the detection sensitivity of the 1 st sensor portion 406A is improved. Therefore, for example, compared to a case where two sensor elements for 1 axis are mounted to constitute a multi-axis angular velocity sensor, the arrangement space of the sensor elements 401 in the mounting base 55 can be made equal, and the detection sensitivity can be improved.

[ modification of shape of piezoelectric Material ]

A modification of the shape of the piezoelectric body will be described with reference to fig. 11 to 12 (d). The modifications exemplified below can be applied to any of embodiments 1 to 4. Note that the concept according to the modification from the embodiment to the modification can be applied to embodiment 5 described later.

(modification 1)

Fig. 11 is a plan view showing a main part of a sensor element (piezoelectric body 503) according to modification 1.

In embodiment 1, two units 5 are arranged so that the holding portions 11 side face each other. On the other hand, in the present modification, the two units 5 are arranged so that the base 9b sides face each other.

In embodiment 1, the support portion 7 is formed in an H shape in a plan view. On the other hand, in the present modification, the support portion 507 is formed in a frame shape surrounding a predetermined number (two in the present modification) of the units 5 in a plan view. In this case, the plurality of terminals 27 may be located at appropriate positions of the frame-shaped support portion 507, may be arranged at 4 corners (an example shown in the figure), or may be arranged at other positions.

(modification 2)

Fig. 12 (a) is a plan view showing a main part of a piezoelectric body 603 according to a modification example 2. As shown in the drawing, the driving arm 13 and the detection arm 15 may extend from the base 9b to the inside of the opening 9a, or may extend from the base 9b to the outside of the opening 9a. In this configuration, the pair of drive arms 13 extending into the opening 9a and the pair of drive arms 13 extending outward from the opening 9a are excited in mutually opposite phases. The structure and the operation thereof are described with reference to the structure and the operation thereof disclosed in fig. 9(a) to 10(b) of patent document 1.

(modification 3)

Fig. 12 (b) is a plan view showing a main part of the piezoelectric body 703 according to the modification 3. As shown in the figure, the drive arm 13 extends from the base 9b into the opening 9a, and the detection arm 15 extends from the base 9b to the outside of the opening 9a.

(modification 4)

Fig. 12 (c) is a plan view showing a main part of a piezoelectric body 803 according to a 4 th modification example. As shown in this figure, in contrast to the above-described modification 3, the drive arm 13 extends from the base 9b to the outside of the opening 9a, and the detection arm 15 extends from the base 9b to the inside of the opening 9a.

(modification 5)

Fig. 12 (d) is a plan view showing a main part of the piezoelectric body 903 according to the 5 th modification. As shown in the drawing, in contrast to the embodiment, the driving arm 13 and the detection arm 15 may extend from the base portion 9b only outward of the opening 9a. In this case, the frame 9 does not need to have a size surrounding the driving arm 13 and the detection arm 15.

[ 5 th embodiment ]

Fig. 13 is a plan view showing a schematic configuration of the inside of an angular velocity sensor 1051 according to embodiment 5, and corresponds to fig. 1 of embodiment 1.

The sensor element 1001 according to embodiment 5 differs from the sensor element 1 according to embodiment 1 in the position of the drive arm 13. Specifically, in each cell 5 of the piezoelectric body 3 of embodiment 1, the drive arm 13 extends from the base portion 9b of the frame portion 9. In contrast, in each cell 1005(1005A or 1005B) of the piezoelectric body 1003 according to embodiment 2, the driving arm 13 extends from the facing portion 9c.

The position of the drive arm 13 in the x-axis direction can be set to the same position as in embodiment 1, for example. In this case, the base portion 9b in the description of embodiment 1 may be replaced with the opposing portion 9c. Therefore, for example, the two drive arms 13 may be provided at symmetrical positions with respect to the center position of the opposing portion 9c in the x-axis direction. In the present embodiment, it can be said that the two drive arms 13 extend from portions located on both sides in the x-axis direction with respect to the connecting position between the facing portion 9c and the holding portion 11 among the facing portions 9c. The holding portion 11 may be coupled to the central position of the facing portion 9c in the x-axis direction, for example, as described in embodiment 1.

As in embodiment 1, the detection arm 15 is located between the two drive arms 13 in the x-axis direction, for example, and is located at the center of the base 9b in the x-axis direction, for example. Unlike embodiment 1, the drive arm 13 and the detection arm 15 extend in opposite directions to each other. The drive arm 13 and the detection arm 15 overlap each other at a part of the tip side (each range in the y-axis direction) when viewed from the x-axis direction. Although not particularly shown, the drive arm 13 and the detection arm 15 may be provided without being overlapped when viewed in the x-axis direction, or the position of the detection arm 15 in the x-axis direction may not be provided between the two drive arms 13.

In embodiment 1, basically, the flexure of the base portion 9b in the frame portion 9 is intentional, and the flexure of other portions (the opposing portion 9c and the two side portions 9d) of the frame portion 9 is unintentional. On the other hand, as will be understood from the operation description to be described later, in the present embodiment, the opposing portions 9c and the two side portions 9d are also intentionally bent in addition to the base portion 9b. The specific dimensions of the opposing portion 9c and the two side portions 9d may be different from those of embodiment 1 in accordance with the difference in operation. For example, the length and width of the opposing portion 9c and the side portion 9d may be set so that the resonance frequency of the flexure is close to the frequency at which the drive arm 13 is excited.

Fig. 14 (a) and 14 (b) are schematic plan views for explaining the excitation of the piezoelectric body 1003. These drawings correspond to fig. 5 (a) and 5 (b) of embodiment 1.

In each unit 1005, the pair of driving arms 13 are excited as in embodiment 1. That is, the pair of drive arms 13 are excited in mutually opposite phases so as to deform toward opposite directions to each other in the x-axis direction.

At this time, as shown in fig. 14 (a), when the pair of drive arms 13 are flexed outward in the x-axis direction (on the side where the pair of drive arms 13 are separated from each other), the bending moment is transmitted to the base portion 9b via the opposing portion 9c and the two side portions 9d, and the base portion 9b is flexed on the y-axis direction side. Specifically, one side in the y-axis direction is a direction from the distal end side to the proximal end side of the driving arm 13, and is a-y side in the unit 1005A and a + y axis in the unit 1005B. Further, a portion on one side of the opposing portion 9c with respect to the holding portion 11 (+ x-side portion or-x-side portion) can be regarded as a cantilever beam supported by the holding portion 11. The end portion (the portion connected to the side portion 9d) of the cantilever receives a bending moment from the driving arm 13 and is displaced to one side in the y-axis direction (the same side as the one side in the y-axis direction relating to the deflection of the base portion 9 b). Further, the two side portions 9d and the base portion 9b are displaced to the one side in the y-axis direction. The detection arm 15 is displaced to the one side in the y-axis direction by at least one of the deflection and the displacement of the base portion 9b.

On the contrary, as shown in fig. 14 (b), when the pair of drive arms 13 are flexed inward in the x-axis direction (the side where the pair of drive arms 13 approach each other), the bending moment is transmitted to the base portion 9b via the opposing portion 9c and the two side portions 9d, and the base portion 9b is flexed to the other side in the y-axis direction. The other side in the y-axis direction is, specifically, the direction from the base side to the distal end side of the driving arm 13, and is the + y side in the unit 100SA and the-y axis in the unit 1005B. Further, the end of the cantilever-shaped portion (+ x-side portion or-x-side portion) of the opposing portion 9c with respect to the holding portion 11 is displaced to the other side in the y-axis direction (the same side as the other side in the y-axis direction relating to the deflection of the base portion 9 b) by receiving a bending moment from the driving arm 13. Further, the two side portions 9d and the base portion 9b are displaced in the other side in the y-axis direction. The detection arm 15 is displaced to the other side in the y-axis direction by at least one of the deflection and the displacement of the base portion 9b.

As described above, in each unit 1005, the displacement (vibration) of the detection arm 15 in the y-axis direction is detected as in the previous embodiment. Therefore, for example, as in embodiment 1, the angular velocity around the z-axis can be detected by the two units 1005. Further, for example, as in embodiment 2, the angular velocity around the x-axis can be detected by the two units 1005. Further, for example, as in embodiment 3, the angular velocity around the z-axis can be detected by one of the two units 1005, and the angular velocity around the x-axis can be detected by the other of the two units 1005.

As described above, in the present embodiment, angular velocity sensor 1051 includes sensor element 1001 and mounting base 55 supporting sensor element 1001. The sensor element 1001 includes a piezoelectric body 1003, a plurality of excitation electrodes 21, and a plurality of detection electrodes 23. The piezoelectric body 3 includes at least two driving arms 13 and a detection arm 15. The two drive arms 13 extend in parallel with each other in the y-axis direction at positions separated from each other in the x-axis direction of the orthogonal coordinate system xyz. The detection arm 15 extends in the y-axis direction. The plurality of excitation electrodes 21 are located on the two drive arms 13 in an arrangement and connection relationship in which the two drive arms 13 are excited with mutually opposite phases in the x-axis direction. The plurality of detection electrodes 23 are located in the detection arm 15 in an arrangement for extracting a signal generated by the vibration of the detection arm 15 in the x-axis direction or the z-axis direction.

In the present embodiment, the piezoelectric body 1003 includes the frame portion 9, the holding portion 11, and the supporting portion 7 as viewed in the z-axis direction. The frame 9 forms an opening 9a when viewed in the z-axis direction. The frame 9 includes a base portion 9b having a longitudinal direction in the x-axis direction and an opposing portion 9c located on the opposite side of the base portion 9b with the opening 9a interposed therebetween, as a part of the periphery of the opening 9a. The holding portion 11 extends outward of the opening 9a (e.g., in the y-axis direction) from the facing portion 9c when viewed in the z-axis direction. The supporting portion 7 is connected to the holding portion 11 on the side opposite to the facing portion 9c side, and is supported by the mounting base 55. The two drive arms 13 extend from portions of the opposing portion 9c that are located on both sides in the x-axis direction with respect to the connecting position between the opposing portion 9c and the holding portion 11. The detection arm 15 extends from the base 9b.

Therefore, for example, the detection accuracy can be improved. For example, as described above in embodiment 1, when the support portion 7 deforms due to curing shrinkage of the bump 59, the frame portion 9 is supported by the holding portion 11, and thus the frame portion 9 is not easily deformed although it is displaced. That is, the possibility that unintentional stress is given to the frame portion 9 is reduced. For example, the detection arm 15 can be displaced by only the deflection of the base portion 9b as compared with the embodiment 1, but in the present embodiment, the detection arm 15 can be displaced by the deflection of the base portion 9b or the displacement of the base portion 9b due to the deflection of the facing portion 9c. As a result, the displacement of the detection arm 15 is increased, and the sensitivity is easily improved.

(modification of embodiment 5)

Fig. 15 is a plan view showing a main portion of a sensor element (piezoelectric body 1103) according to a modification of embodiment 5.

In modification 1 shown in fig. 11, two units 5 may be arranged so that the base portions 9b side face each other in embodiments 1 to 4. Similarly, in embodiment 5, two units 1005 may be disposed so that the base portions 9b of the two units 5 face each other. Fig. 15 shows such a modification.

Although not particularly shown, in embodiment 5, a driving arm 13 extending from the facing portion 9c into the opening 9a, a driving arm 13 extending from the facing portion 9c to the outside of the opening 9a, a detecting arm 15 extending from the base portion 9b into the opening 9a, and a detecting arm 15 extending from the base portion 9b to the outside of the opening 9a may be provided in a similar manner to the modification 2 ((a) of fig. 12). In a similar manner to the modification 3 (fig. 12 (b)), a driving arm 13 extending from the facing portion 9c into the opening 9a and a detecting arm 15 extending from the base portion 9b to the outside of the opening 9a may be provided. In a similar manner to the modification 4 (fig. 12 (c)), a driving arm 13 extending from the facing portion 9c to the outside of the opening 9a and a detection arm 15 extending from the base portion 9b to the inside of the opening 9a may be provided. In a similar manner to the modification 5 (fig. 12 (d)), a driving arm 13 extending from the facing portion 9c to the outside of the opening 9a and a detection arm 15 extending from the base portion 9b to the outside of the opening 9a may be provided.

The technique according to the present disclosure is not limited to the above embodiment, and can be implemented in various ways.

The sensor element or the angular velocity sensor can be formed as part of mems (micro Electro Mechanical systems). In this case, the piezoelectric body constituting the sensor element may be mounted on the MEMS substrate, or the MEMS substrate may be formed of the piezoelectric body and a part of the piezoelectric body constituting the sensor element. In the former case, for example, the MEMS substrate is an example of a mounting base, and in the latter case, for example, the MEMS substrate is an example of a support.

As disclosed in patent document 1 and the like, two or more drive arms corresponding to 1 drive arm may be provided. For example, in embodiment 1, a pair of drive arms may be further provided inside or outside the pair of drive arms 13A and 13B. The pair of additional drive arms are arranged line-symmetrically with respect to an unillustrated symmetry axis passing through the center of the base 9B and parallel to the y axis, for example, as in the pair of drive arms 13A and 13B. Two drive arms adjacent to each other on the + x side or the-x side with respect to the symmetry axis are excited with the same phase, and function as one drive arm.

The sensor element is not limited to being mounted on the mounting substrate by a conductive bump interposed between the lower surface of the support portion and the upper surface of the mounting substrate. For example, the sensor element may be fixed to the mounting substrate by an insulating bump interposed between the lower surface of the support portion and the upper surface of the mounting substrate, and the bonding wire may be connected to a terminal located on the upper surface of the sensor element to mount the sensor element. In this case, for example, a material having a low young's modulus can be selected as the material of the bump. The sensor element may be supported by providing a leaf spring-like terminal joined to the support portion and the mounting base.

The embodiments 1 to 5 may be combined. For example, in embodiment 5, in addition to the drive arm extending from the opposing portion, a drive arm extending from the base portion may be provided as in embodiments 1 to 3. Further, the drive arms may be excited so that: when the two drive arms extending from the opposing portion approach each other in the x-axis direction, the two drive arms extending from the base portion also approach each other in the x-axis direction, and when the two drive arms extending from the opposing portion separate from each other in the x-axis direction, the two drive arms extending from the base portion also separate from each other in the x-axis direction.

Description of the symbols

51 (and 251 and 1051).. angular velocity sensor, 1 (and 201, 301, 401 and 1001). sensor element, 3 (and 403, 503, 1003 and 1103). piezoelectric body, 7, 507.. support portion, 9.. frame portion, 9a.. opening, 9b.. base portion, 9c.. facing portion, 11.. holding portion, 13.. drive arm, 15.. detection arm, 21.. excitation electrode, 23.. detection electrode, 55.. mounting base body.