JP2011158319A - Angular velocity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angular velocity sensor element having a sensitivity and accuracy higher as compared to conventional sensors, and enhanced in durability. <P>SOLUTION: This angular velocity sensor device 1 includes a drive section, which has a frame body 6 in the shape of a regular polygon and a plurality of mass substances 7a, 7b, 7c, 7d connected to the frame body 6. The frame body 6 is composed of a plurality of drive beams 5a, 5b, 5c, 5d corresponding to the sides of the polygon. The angular velocity sensor device 1 further includes a detection section including a plurality of detection beams 3a, 3b, 3c, 3d, which is equivalent to straight lines connecting the central base 2 equivalent to the center point of the polygon, to the vertexes of the polygon. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an angular velocity sensor that detects an angular velocity of an object.

  Conventionally, as an angular velocity sensor for detecting the angular velocity of an object or its sensor element, it is caused by Coriolis force (Coriolis force), which is a kind of inertial force generated when rotation is applied to a vibrating mass body. A device that detects weak vibrations and displacements via a piezoelectric element, and detects and measures rotation (operation) in each direction is known. Such angular velocity sensors are widely used in technologies for autonomously controlling the attitude of automobiles, ships, aircraft, rockets, etc., and recently, small electronic devices such as car navigation systems, digital cameras, video cameras, and mobile phones. It has come to be installed in. Along with this, there is a demand for further enhancement of sensitivity, miniaturization and durability of the angular velocity sensor, and various angular velocity sensors using piezoelectric thin films formed by microfabrication techniques have been proposed in response to this demand.

  However, such a piezoelectric thin film is generally very thin and lightweight, so that it is easily affected by vibrations and shocks from the outside of the device or system in which the angular velocity sensor is mounted. The angular velocity tends to be erroneously detected due to noise (disturbance noise) caused by the noise. In order to prevent such inconvenience, for example, Patent Document 1 describes an angular velocity sensor 100 in which a lead frame 20 is provided between the tuning fork vibrator 10 and the package 30.

JP 2006-308543 A

  However, in the angular velocity sensor 100 described in the above-mentioned conventional Patent Document 1, since the drive electrode 14 and the detection electrode 11 are provided in the same tuning fork vibrator 10, the drive vibration and the detection vibration are mixed. As a result, the magnitude (displacement) of the detection vibration due to the Coriolis force is extremely small compared to the drive vibration, so that the detection sensitivity and accuracy of the angular velocity are naturally limited, and further improvement in detection sensitivity and accuracy is realized. It tends to be difficult.

  Further, in this conventional angular velocity sensor 100, the vibration (drive vibration) of the tuning fork vibrator 10 propagates to the lead frame 20, so that the connection portion of the package 30 with the lead frame 20 is repeatedly bent, thereby There is a concern that the durability of the part may be reduced to an inconvenient level.

  In recent years, a combined sensor in which different sensors such as a gyro sensor (including a multi-axis angular velocity sensor) and an acceleration sensor are packaged has been put into practical use. For example, ESC (Electronic Stability Control) (registered trademark) ) Used in vehicle attitude control systems such as systems. Such a combine sensor is enclosed in a package so as to have an optimum buffering capacity against temperature, humidity, disturbance vibration and shock inside the vehicle, and is installed inside the vehicle to be mounted. However, even if the combine sensor is packaged and installed in this way, the vibration of the drive part of the gyro sensor may be a noise source that adversely affects the yaw detection unit, and the multi-axis angular velocity In the case of a sensor, there is a possibility that the noise becomes disturbance noise with respect to another angular velocity sensor or the like in the package.

  Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an angular velocity sensor that has higher sensitivity and higher accuracy than conventional ones and can improve durability.

  In order to solve the above problems, an angular velocity sensor according to the present invention includes a frame having a polygonal shape, and a plurality of mass bodies (weight, weight, weight body, mass) connected to the frame. And a detection unit connected to the frame.

  In the angular velocity sensor having such a configuration, the sides and the plurality of mass bodies of the polygonal frame provided in the drive unit are regulated according to the shape of the frame (for example, the polygonal surface direction). ), The displacement of the detection unit at that time is detected, and the Coriolis force, and thus the angular velocity, can be detected and measured based on the detection signal. (Operation in vibration detection mode).

  At this time, although the detection unit is connected to the frame body, each side of the frame body and each of the plurality of mass bodies are in phase (perpendicular to the extending direction (plane direction) of the frame body in the inner region of the frame body). By driving in the displacement direction of the vibration with respect to the shaft (that is, the direction toward or away from the shaft and the vibration cycle are the same), the vibration of the drive unit is not transmitted to the detection unit, in other words, The drive vibration of each side of the frame body is canceled (cancelled) at the apex portion of the frame body, so that the vibration of the drive unit is not transmitted to the detection unit, so that the detection unit is stopped without being displaced. obtain. Therefore, the detection sensitivity and accuracy of the Coriolis force detected by the detection unit can be improved.

  Further, if this angular velocity sensor is installed in a housing such as a package via a detection unit through which vibration of the driving unit is not transmitted, the package as assumed in the above-described conventional angular velocity sensor 100 described in Patent Document 1 is provided. Since bending that repeatedly occurs at the connection portion between the lead frame 20 and the lead frame 20 can be suppressed, the durability of the package including the angular velocity sensor can be significantly improved.

  Further, in the conventional angular velocity sensor 100, it is assumed that the tuning fork vibrator 10 is connected to the package 30 via the lead frame 20 to prevent the propagation of disturbance noise. Such a connection structure via the lead frame 20 requires high assembly accuracy, and the manufacturing cost increases accordingly. In contrast, the angular velocity sensor according to the present invention does not require a complicated connection structure using a conventional lead frame. As described above, the angular velocity sensor is attached to a housing such as a package via a detection unit that does not transmit vibration of the drive unit. Since it can be easily installed, it is advantageous from the viewpoint of economy.

  Furthermore, since the angular velocity sensor 100 described in the above-described conventional patent document 1 uses vibration in a direction perpendicular to the installation plane of the tuning fork vibrator 10 as detection vibration, Since a sufficient clearance (gap) for vibration in this direction is required, there is a limit to the size reduction of the package including the angular velocity sensor 100. On the other hand, in the angular velocity sensor according to the present invention, as described above, the drive unit is vibrated in the polygonal surface direction of the frame (that is, in-plane vibration), so that the clearance in the direction perpendicular to the surface direction is minimized. Since it can be possible to narrow, further downsizing of elements, devices, equipment, etc. can be realized.

  Furthermore, in the angular velocity sensor according to the present invention, as described above, the vibration of the drive unit can be prevented from being transmitted to the detection unit. Therefore, even if the angular velocity sensor is installed in a housing such as a package via the detection unit. The vibration of the drive unit cannot propagate to the outside of the angular velocity sensor element, that is, the housing side. Therefore, even when the angular velocity sensor element according to the present invention is combined with another sensor such as an acceleration sensor to form a combined sensor, the angular velocity sensor itself is prevented from becoming a noise source that adversely affects other sensors. Can be done.

  In the above aspect, in the drive unit, each side of the frame (and a plurality of mass bodies connected thereto) is displaced or vibrated in the same phase in the polygonal plane direction (driven in the same phase vibration mode). It is preferable that it is. In this case, if the polygon that defines the frame is a regular polygon or a substantially regular polygon, the displacement of each side of the frame and each of the mass bodies are synchronized compared to the case where the polygon is not a regular polygon. This makes it easier to cause the same phase vibration.

  Specifically, the frame has a plurality of driving beams corresponding to the sides of the polygon, and the detection unit connects the base located inside the polygon and each vertex of the polygon. And a configuration having a plurality of detection beams provided in. If comprised in this way, since a detection part is accommodated in the inner area | region of a drive part, and the vibration direction of a detection beam becomes parallel to the extension direction (polygonal surface direction) of a frame, an angular velocity sensor element Further reduction in height and size can be realized. In addition, even if the base is connected and fixed to a housing such as a package, mechanical vibrations are applied to the base because the drive vibration of the drive is prevented from propagating to the base via the detector. Since there is no (concentration of stress due to bending), the durability of the angular velocity sensor can be improved even in this case.

  From the viewpoint of making the detection beams equal in length and making the detection sensitivity uniform, the frame body has a regular polygon shape, and the base is provided at a position corresponding to the center point of the regular polygon. It is preferred that

  More specifically, each of the plurality of mass bodies is provided in each of the plurality of driving beams, each of the plurality of driving beams has at least a pair of driving piezoelectric elements, and A configuration in which each of the detection beams has at least a pair of detection piezoelectric elements is exemplified. In this case, each of the plurality of driving beams can be configured to vibrate in the same phase so that at least a pair of the driving piezoelectric elements are displaced (approached / separated) from the base portion by expansion and contraction.

  In addition, the angular velocity sensor according to the present invention has at least two sides (and mass bodies connected to each side) adjacent to each other of the sides of the frame of the drive unit in opposite phases (frames). Displacement in the direction of vibration displacement with respect to an axis perpendicular to the extending direction (plane direction) of the frame in the inner region of the body (that is, the direction toward or away from the axis is opposite and the vibration period is the same) or Even those that vibrate are suitable. That is, for example, when the drive unit has a plurality of drive beams and the detection unit has a detection beam, any one of the plurality of drive beams is directed in the direction toward the base. It may be driven so that displacement or vibration of the same period in which one of the driving beams that are displaced and that is adjacent to the driving beam is displaced away from the base is generated.

  In this way, in a state where no Coriolis force is generated, it is possible to apply a stress to the detection beam connected between (the top of) the adjacent drive beams to cause displacement, and the displacement is Confirming (detecting) whether or not it can be detected, that is, based on the presence or absence and magnitude of the detection signal at that time, the detection beam, the driving piezoelectric element and / or the detection piezoelectric element provided in the detection unit, Furthermore, it is possible to perform self-diagnosis (operation in the self-diagnosis mode) such as breakage (including short-circuiting, disconnection, etc.) and malfunction of circuits connected to the piezoelectric elements.

  In addition, according to this configuration, even if a defect occurs in a part of the detection beam or the piezoelectric element, signal data obtained from the defective detection beam and the piezoelectric element is excluded, thereby improving the detection accuracy of the angular velocity sensor. It is possible to improve the reliability of the system. In addition, such a self-diagnosis result can be used as an index of replacement or maintenance time of the angular velocity sensor or the sensor package provided with the angular velocity sensor.

It is a perspective view which shows the structure of the angular velocity sensor element which concerns on 1st Embodiment. It is a top view which shows the operation state in the vibration detection mode of the angular velocity sensor element which concerns on 1st Embodiment. It is a top view which shows the operation state in the vibration detection mode of the angular velocity sensor element which concerns on 1st Embodiment. It is a top view which shows the operation state in the vibration detection mode of the angular velocity sensor element which concerns on 1st Embodiment. It is a top view which shows the structure of the angular velocity sensor element which concerns on 2nd Embodiment. It is a top view which shows the structure of the angular velocity sensor element which concerns on 3rd Embodiment. It is a top view which shows the operation state in the self-diagnosis mode of the angular velocity sensor element which concerns on 1st Embodiment. It is a top view which shows the operation state in the self-diagnosis mode of the angular velocity sensor element which concerns on 3rd Embodiment. (A)-(F) are process drawings (process flow figure; schematic sectional drawing) which show an example of the state which manufactures the package (sensor package) provided with the angular velocity sensor element by this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. Further, the following embodiments are exemplifications for explaining the present invention, and are not intended to limit the present invention only to the embodiments. Furthermore, the present invention can be variously modified without departing from the gist thereof.

<First Embodiment>
FIG. 1 is a perspective view showing an example of the configuration of an angular velocity sensor element 1 (angular velocity sensor) according to the first embodiment of the present invention. In the figure, the angular velocity sensor element 1 extends in the XY direction on the paper surface, and its thickness (Z-direction thickness) is exaggerated for easy understanding.

  The angular velocity sensor element 1 has an element center α and a central base 2 (base) having a substantially circular shape arranged around the element center α. The central base 2 is provided in a sensor package (housing) not shown. Fixed and connected to the circuit board. Further, one end of detection beams 3a, 3b, 3c, 3d having a straight shape is connected to the center base portion 2, and these detection beams 3a, 3b, 3c, 3d are respectively + Y direction from the center base portion 2. , + X direction, −Y direction, and −X direction (that is, in a cross shape).

  Furthermore, a square frame 6 is connected to the other ends of the detection beams 3a, 3b, 3c, 3d. The frame 6 is composed of drive beams 5a, 5b, 5c and 5d extending so as to connect (link) the corners 4a, 4b, 4c and 4d located at the apexes of the square. Further, masses 7a, 7b, 7c, and 7d (all of which are mass bodies) are integrally provided on the drive beams 5a, 5b, 5c, and 5d, respectively.

  In other words, the frame 6 has a square shape with the drive beams 5a, 5b, 5c, and 5d as four sides, and the detection beams 3a and 3c have corners 4a and 3c corresponding to the opposite vertices in the square. Similarly, the detection beams 3b and 3d correspond to diagonal lines connecting the corners 4b and 4d corresponding to the opposite vertices in the square. It can also be expressed that the element center α in the central base 2 corresponds to the intersection of these diagonal lines, that is, the center of the square. In the figure, the corners 4a, 4b, 4c, 4d of the frame 6 are smoothly chamfered at the corners and have a so-called round (R) shape.

  In addition, the masses 7a, 7b, 7c, and 7d are sandwiched between the drive beams 5a, 5b, 5c, and 5d at the center portions of the drive beams 5a, 5b, 5c, and 5d, respectively (to be sandwiched). ) It has a pair of auxiliary masses provided. That is, for example, the mass 7 a includes an auxiliary mass 70 a formed in a direction away from the central base 2 and an auxiliary mass 71 a formed in a direction toward the central base 2. Similarly, the mass 7b has auxiliary masses 70b and 71b, the mass 7c has auxiliary masses 70c and 71c, and the mass 7d has auxiliary masses 70d and 71d.

  Of these auxiliary masses, the shapes of the auxiliary masses 71a, 71b, 71c, 71d disposed in the inner region of the frame body 6 are not particularly limited. For example, as shown in the figure, the center base 2, the detection beam 3a, 3b, 3c, 3d, corners 4a, 4b, 4c, 4d and a substantially trapezoidal shape so as to conform to the shapes of the spaces 9a, 9b, 9c, 9d defined by the drive beams 5a, 5b, 5c, 5d. Is formed. On the other hand, the shape of the auxiliary masses 70a, 70b, 70c, 70d disposed in the outer region of the frame body 6 is not particularly limited, and is substantially the same as the shape of the auxiliary masses 71a, 71b, 71c, 71d, for example. The drive beams 5a, 5b, 5c and 5d are arranged so as to be line symmetric with respect to each other. In the present embodiment, the auxiliary masses 70a, 71a, 70b, 71b, 70c, 71c, 70d, and 71d are formed of the same material, and thus all have the same mass.

  A pair of driving piezoelectric elements 10 and 10 arranged in parallel with each other along the extending direction of the driving beams 5a, 5b, 5c and 5d are provided on the upper surfaces of the driving beams 5a, 5b, 5c and 5d, respectively. ', 11, 11', 12, 12 ', 13, 13' are provided. Here, the driving piezoelectric elements 10, 11, 12, and 13 are disposed outside the driving beams 5a, 5b, 5c, and 5d (in a direction away from the center base portion 2; outward), while the driving piezoelectric elements are provided. 10 ', 11', 12 ', and 13' are arrange | positioned inside drive beam 5a, 5b, 5c, 5d (direction toward the center base part 2; inward). These pair of driving piezoelectric elements 10, 10 ', 11, 11', 12, 12 ', 13, 13' are respectively connected to a control circuit (not shown) through electrical wiring (not shown). They are connected and electrically controlled by the control circuit to expand and contract the element itself. As a result, the drive beams 5a, 5b, 5c, 5d move from the central base 2 in the direction toward the central base 2 of the angular velocity sensor element 1 along the plane including the frame body 6 and the masses 7a, 7b, 7c, 7d. It is displaced in a direction away from it and vibrates alternately and periodically.

  On the other hand, on the upper surfaces of the detection beams 3a, 3b, 3c, 3d, a pair of detection piezoelectric elements 14, 14 arranged in parallel with each other along the extending direction of the detection beams 3a, 3b, 3c, 3d, respectively. ', 15, 15', 16, 16 ', 17, 17' are provided. These pair of detection piezoelectric elements 14, 14 ′ 15, 15 ′, 16, 16 ′, 17, 17 ′ are given rotation (force) around the Z-axis direction to the angular velocity sensor element 1 as will be described later. Displacement vibration in the rotational direction around the element center α of the angular velocity sensor element 1 generated due to Coriolis force (the detection beams 3a and 3c are substantially vibrations in the ± X-axis direction). The detection beams 3b and 3d are substantially vibrations in the ± Y-axis direction.). Thus, the detection piezoelectric elements 14, 14 ', 15, 15', 16, 16 ', 17, 17' in the present embodiment are paired in the detection beams 3a, 3b, 3c, 3d. As a result, the detection accuracy of the angular velocity is further improved, and the detection sensitivity is further remarkably improved by the presence of a plurality of detection beams (four in this embodiment, 3a, 3b, 3c, and 3d).

  Thus, in the angular velocity sensor element 1, the frame body 6, the masses 7a, 7b, 7c, and 7d, the driving beams 5a, 5b, 5c, and 5d, and the driving piezoelectric elements 10, 10 ′, 11, and 11 are mainly used. ', 12, 12', 13, 13 'constitutes a drive unit, and mainly includes detection beams 3a, 3b, 3c, 3d, and detection piezoelectric elements 14, 14', 15, 15 ', The detection part is comprised from 16, 16 ', 17, 17'.

  2A and 2B are plan views schematically showing a state in which the angular velocity sensor element 1 is operating in the vibration detection mode.

  In FIG. 2A, the angular velocity sensor element 1 is initially set by a pair of driving piezoelectric elements 10, 10 ′, 11, 11 ′, 12, 12 ′, 13 by a control signal from a control circuit (not shown). , 13 ′ (not shown), the driving piezoelectric elements 10, 11, 12, 13 contract and the driving piezoelectric elements 10 ′, 11 ′, 12 ′, 13 ′ expand to drive. The beams 5a, 5b, 5c and 5d are displaced in the same phase (aligned) in the direction toward the central base 2 of the angular velocity sensor element 1.

  2A shows a state in which the driving beams 5a, 5b, 5c, and 5d are closest to the central base 2 of the angular velocity sensor element 1, for example, and are provided on the driving beam 5a. Focusing on the auxiliary mass 71a, the top side 72a 'of the trapezoidal auxiliary mass 71a is closest to the center base 2 in the state shown in FIG. Similarly, the oblique sides 73a 'and 74a' of the auxiliary mass 71a are closest to the detection beams 3a and 3b, respectively, but are not in contact with each other.

  Further, the auxiliary mass 71a is connected to the driving beam 5a at the connecting portion 77a 'located at the center of the bottom 75a', and as described above, the auxiliary mass 71a is symmetrical with the auxiliary mass 71a with the driving beam 5a interposed therebetween. The provided auxiliary mass 70a is connected to the drive beam 5a at a connection portion 77a having the same shape as the connection portion 77a ′. When the driving beam 5a is closest to the central base 2 of the angular velocity sensor element 1 (the state shown in FIG. 2A), the driving beam 5a bent toward the central base 2 and the bottom 75a of the auxiliary mass 70a The distance (distance) between the two is set as appropriate so that they do not contact each other.

  On the other hand, in FIG. 2B, the angular velocity sensor element 1 includes a pair of driving piezoelectric elements 10, 10 ′, 11, 11 ′, 12, 12 ′, 13, 13 ′ according to a control signal from a control circuit (not shown). (Not shown), the driving piezoelectric elements 10, 11, 12, 13 are expanded and the driving piezoelectric elements 10 ′, 11 ′, 12 ′, 13 ′ are contracted, thereby driving beams 5 a, 5 b, 5c and 5d are displaced in the direction away from the center base portion 2 of the angular velocity sensor element 1 in the same phase (aligned).

  2B shows a state in which the drive beams 5a, 5b, 5c, and 5d are farthest from the center base portion 2 of the angular velocity sensor element 1, for example. In this state, the state opposite to FIG. 2A is shown. The distance (distance) between the drive beam 5a bent in the direction and the bottom side 75a 'of the auxiliary mass 71a is set as appropriate so as not to contact.

  FIG. 2C is also a plan view schematically showing a state in which the angular velocity sensor element 1 is operating in the vibration detection mode, and is a diagram showing a mechanism for detecting Coriolis force in the vibration detection mode.

Coriolis force is a kind of inertial force recognized in rotating coordinates (rotating coordinate system), and generally, the following formula (1);
Fc = 2 mV × Ω (1),
Is a force received by a mass (mass body) having a mass m and moving at a velocity V in a coordinate system rotating at an angular velocity Ω.

  FIG. 2C shows the driving beams 5a, 5b, 5c, 5d of the angular velocity sensor element 1 and the masses 7a, 7b, 7c, 7d provided on the driving beams 5a, 5b, 5c, 5d, respectively. 2A and FIG. 2B show a state of continuously oscillating at the same phase between the displacement states shown in FIG. 2B (the vibration directions of the drive vibrations are indicated by arrows 80a, 80b, 80c, and 80d. ). In the vibration state of the vibration detection mode, when rotation with respect to the Z-axis (rotation indicated by arrow β) occurs, vibration directions 80a, 80b, 80c, and 80d of those drive vibrations occur in the masses 7a, 7b, 7c, and 7d. And a displacement (vibration) based on Coriolis force occurs in a direction perpendicular to (that is, a direction parallel to the extending direction of the driving beams 5a, 5b, 5c, and 5d in a stationary state) (the vibration direction of this detected vibration is , Arrows 81a, 81b, 81c, 81d).

  The vibration displacements 81a, 81b, 81c, 81d in the masses 7a, 7b, 7c, 7d caused by the Coriolis force are the drive beams 5a, 5b, 5c, 5d and the corners 4a, 4b of the frame body 6. , 4c, 4d to the detection beams 3a, 3b, 3c, 3d to vibrate the detection beams 3a, 3b, 3c, 3d, and their vibration displacements (indicated by arrows 82a, 82b, 82c, 82d). Are detected by the detection piezoelectric elements 14, 14 ', 15, 15', 16, 16 ', 17, 17' provided on the detection beams 3a, 3b, 3c, 3d. Then, the detection signal of the detected vibration is output to a control circuit (not shown) in the package via a signal line (not shown) and, for example, via the center base 2 and the like, and the waveform of the output signal (detected vibration) Is compared with the waveform of the drive vibration in the drive beams 5a, 5b, 5c, and 5d, the angular velocity and the rotation direction generated in the angular velocity sensor element 1 are obtained.

  According to the angular velocity sensor element 1 in the first embodiment shown in FIGS. 2A to 2C configured as described above, the drive beams 5a and 5c are symmetrically arranged so as to face each other with the center base portion 2 interposed therebetween. Similarly, the driving beams 5b and 5d are symmetrically arranged so as to face each other with the central base 2 interposed therebetween, and the driving beams 5a, 5b, 5c and 5d and the masses 7a, 7b, 7c and 7d are driven in the same phase. Since it is vibrated, the driving vibration is significantly canceled at the four corners 4a, 4b, 4c, and 4d corresponding to the apexes of the square frame 6. Accordingly, since the drive vibration is prevented from propagating to the detection beams 3a, 3b, 3c, 3d, the detection sensitivity and detection accuracy of the angular velocity sensor element 1 can be remarkably improved.

  Further, since the drive vibration is prevented from propagating to the detection beams 3a, 3b, 3c, 3d, the drive vibration is also prevented from propagating to the central base 2. Therefore, it is possible to prevent mechanical stress from being applied to the center base 2 and to improve the durability of the connection portion between the center base 2 and a housing such as a package. Even in a sensor package including a sensor, the angular velocity sensor element 1 can be prevented from becoming a disturbance noise source for other sensors such as an acceleration sensor. Thereby, the further functional improvement of this sensor package can be achieved.

  Further, as described above, since the angular velocity sensor element 1 has a multi-mass structure (a structure having four masses in the first embodiment), the mass of the driving mass used as a whole can be increased more significantly. It becomes possible. As a result, the vibration displacement caused by the detected Coriolis force can be further increased, and the sensitivity of the angular velocity sensor element 1 can be further improved in this respect. In addition, the angular velocity sensor element 1 according to the present embodiment has the drive vibrations 80a, 80b, 80c, and 80d and the detection vibrations 81a, 81b, 81c, and 81d in the same plane. As a result, the sensor package can be easily reduced in size and thickness.

  In the present embodiment, in addition to the above configuration, the width of the beams at both end portions of the drive beams 5a, 5b, 5c, 5d (portions close to the connection portions with the corners 4a, 4b, 4c, 4d) is the central portion. You may comprise so that it may become narrow compared with. In this case, the driving vibrations 80a, 80b, 80c, 80d of the driving beams 5a, 5b, 5c, 5d by the driving piezoelectric elements 10, 10 ′, 11, 11 ′, 12, 12 ′, 13, 13 ′ are extremely smooth. Thus, higher-speed drive vibration can be applied to the masses 7a, 7b, 7c, and 7d. Thereby, since the generated Coriolis force is further increased, the detection sensitivity of the angular velocity sensor element 1 can be further improved. Similarly, the width of the beams at both ends of the detection beams 3a, 3b, 3c, 3d (portions close to the connection portions with the corners 4a, 4b, 4c, 4d and the central base 2) is narrower than that at the central portion. With this configuration, the detection vibrations 81a, 81b, 81c, 81d in the detection beams 3a, 3b, 3c, 3d become smoother. As a result, the detection sensitivity of the angular velocity sensor element 1 can be further remarkably improved. It is.

  In addition, unnecessary vibrations that may occur in the corners 4a, 4b, 4c, and 4d are alleviated by the smooth vibration operation of the drive beam and the detection beam, and the mechanical force applied to the center base 2 is reduced. Since stress is also relieved, the durability of the angular velocity sensor element 1 and the sensor package including the angular velocity sensor element 1 can be further improved. Further, since no mechanical stress is applied to the central base 2 as described above, the angular velocity sensor element 1 can be more easily fixed and connected to the sensor package by, for example, die bonding, thereby reducing the manufacturing cost. It is also possible to reduce the cost and improve the economy.

Second Embodiment
FIG. 3 is a plan view (top view) showing a second embodiment of the angular velocity sensor element according to the present invention. The angular velocity sensor element 20 (angular velocity sensor) has a regular hexagonal frame body 26 instead of the frame body 6, thereby replacing the four spaces 9 a, 9 b, 9 c, and 9 d of FIG. 1 in the first embodiment. , Center base 2, driving beams 25a, 25b, 25c, 25d, 25e, 25f, corners 24a, 24b, 24c, 24d, 24e, 24f, and detection beams 23a, 23b, 23c, 23d, 23e, 23f. The angular velocities in the first embodiment described above except that 29a, 29b, 29c, 29d, 29e, and 29f are defined and the shapes of the masses 27a, 27b, 27c, 27d, 27e, and 27f are substantially rectangular. It is configured in the same manner as the sensor element 1. Therefore, in FIG. 3, the same reference numerals are given to members common to the angular velocity sensor element 1, and the description thereof is omitted here in order to avoid redundant description.

  In the angular velocity sensor element 20 shown in FIG. 3, the masses 27a, 27b, 27c, 27d, 27e, and 27f are different from the masses 7a, 7b, 7c, and 7d in the angular velocity sensor element 1 and have a small rectangular shape. However, since the number is large, the mass mass of them as a whole can be increased to be equal to or higher than that of the angular velocity sensor element 1. Furthermore, since each mass 27a, 27b, 27c, 27d, 27e, 27f in each drive beam 25a, 25b, 25c, 25d, 25e, 25f is miniaturized, each drive beam 25a, 25b, 25c, 25d, It becomes possible to increase the vibration speed by the driving piezoelectric elements provided in 25e and 25f. Thereby, since the product of the mass and the speed of the mass is increased, the Coriolis force generated in the vibration detection mode can be further increased. For these reasons, the detection sensitivity of the angular velocity sensor element 20 can be further improved.

  Further, the driving beams 25a and 25d are arranged to face each other with the center base portion 2 interposed therebetween, the driving beams 25b and 25e are arranged to face each other with the center base portion 2 interposed therebetween, and the driving beams 25c and 25f are similarly arranged to the center base portion. 2 are opposed to each other and vibrate in the same phase, so that the driving beams 25a, 25b, 25c, 25d, 25e, 25f and the masses 27a, 27b, 27c, 27d, 27e, 27f The drive vibration is significantly canceled at the six corners 24a, 24b, 24c, 24d, 24e, and 24f corresponding to the apexes of the frame body 26. Thereby, it is possible to prevent the drive vibration from propagating to the detection beams 23a, 23b, 23c, 23d, 23e, and 23f, and the detection sensitivity and durability of the angular velocity sensor element 20 can be significantly improved.

  As described above, the regular hexagonal angular velocity sensor element 20 has been particularly referred to in the present embodiment. However, in the present embodiment, an even regular polygon having four or more even angles (sides) such as a regular octagon and a regular decagon. A shaped angular velocity sensor element is included.

<Third Embodiment>
FIG. 4 is a plan view (top view) showing a third embodiment of the angular velocity sensor element according to the present invention. The angular velocity sensor element 30 (angular velocity sensor) has a regular pentagonal frame 36 instead of the frame 6, thereby replacing the four spaces 9 a, 9 b, 9 c, and 9 d of FIG. 1 in the first embodiment. Thus, five spaces 39a, 39b, 39c are formed by the central base 2, the driving beams 35a, 35b, 35c, 35d, 35e, the corners 34a, 34b, 34c, 34d, 34e, and the detection beams 33a, 33b, 33c, 33d, 33e. , 39d, 39e are defined, and the shapes of the masses 37a, 37b, 37c, 37d, 37e are substantially rectangular, and are configured similarly to the angular velocity sensor element 1 in the first embodiment described above. Is. Therefore, in FIG. 4, the same reference numerals are given to members common to the angular velocity sensor element 1, and the description thereof is omitted here in order to avoid redundant description.

  In the angular velocity sensor element 30 shown in FIG. 4, the masses 37a, 37b, 37c, 37d, and 37e are small rectangular shapes, unlike the masses 7a, 7b, 7c, and 7d in the angular velocity sensor element 1. However, since the number is large, the mass mass as a whole can be increased as compared with the angular velocity sensor element 1 or compared with the angular velocity sensor element 1. Furthermore, since the masses 37a, 37b, 37c, 37d, and 37e in the drive beams 35a, 35b, 35c, 35d, and 35e are reduced in size, the drive beams provided in the drive beams 35a, 35b, 35c, 35d, and 35e are used. The vibration speed due to the piezoelectric element can be increased. Thereby, since the product of the mass and the speed of the mass is increased, the Coriolis force generated in the vibration detection mode can be further increased. For these reasons, the detection sensitivity of the angular velocity sensor element 30 can be further improved.

  Further, since the driving beams 35a, 35b, 35c, 35d, 35e surrounding the central base 2 at equal intervals vibrate in the same phase, the driving beams 35a, 35b, 35c, 35d, 35e and the masses 37a, 37b, 37c, 37d, The drive vibration 37e is significantly canceled at the five corners 34a, 34b, 34c, 34d, 34e corresponding to the apex of the frame 36. Thereby, it is possible to prevent the drive vibration from propagating to the detection beams 33a, 33b, 33c, 33d, and 33e, and the detection sensitivity and durability of the angular velocity sensor element 20 can be remarkably improved.

  Furthermore, unlike the angular velocity sensor elements 1 and 20 of the first and second embodiments, the angular velocity sensor element 30 of the third embodiment has a regular polygonal shape in which the frame has an odd number of sides. This also suppresses the propagation of the drive vibration to the detection beams 33a, 33b, 33c, 33d, and 33e, so that the drive vibration is also prevented from propagating to the central base 2. Therefore, it is possible to prevent mechanical stress from being applied to the center base 2 and to improve the durability of the connection portion between the center base 2 and a housing such as a package. Even in a sensor package including a sensor, the angular velocity sensor element 20 can be prevented from becoming a disturbance noise source for other sensors such as an acceleration sensor. Thereby, the further functional improvement of this sensor package can be achieved.

  As described above, the regular pentagonal angular velocity sensor element 30 has been particularly referred to in the present embodiment. However, in the present embodiment, an odd regular polygonal shape having three or more odd angles (sides) such as a regular heptagon and a regular pentagon. The angular velocity sensor element is included.

<Self-diagnosis mode>
As described above, the first to third embodiments of the angular velocity sensor element according to the present invention include a plurality of drive beams, a plurality of detection beams, and at least two piezoelectric elements provided on each of them. It is preferable that the state and operation of these many members can be diagnosed and the presence or absence of a member causing malfunction or the like can be specified as desired.

  FIG. 5 shows the angular velocity sensor element 1 according to the first embodiment operated in the self-diagnosis mode, and is connected to the detection beam, the drive beam, the drive piezoelectric element and / or the detection piezoelectric element, and further to these piezoelectric elements. FIG. 6 is a plan view for explaining an example of a method for self-diagnosis of defects such as breakage (including short circuit, disconnection, etc.) and malfunction of a circuit.

  In the self-diagnosis mode, for example, in the angular velocity sensor element 1 in a state before being operated (operated) in the vibration detection mode, the driving piezoelectric element 10 (not shown) is extended and the driving piezoelectric element 10 ′ (see FIG. The drive beam 5a and the mass 7a are displaced (arrow 83a) in a direction away from the center base 2 by contracting. At the same time, the driving beam 5c and the mass 7c are displaced in the direction away from the central base 2 by extending the driving piezoelectric element 12 (not shown) and contracting the driving piezoelectric element 12 ′ (not shown). Arrow 83c). Note that this self-diagnosis mode may be executed, for example, every time the target device or device on which the angular velocity sensor element is mounted, or every predetermined number of times.

  Similarly, the driving beam 5b and the mass 7b are displaced in the direction toward the central base 2 by contracting the driving piezoelectric element 11 (not shown) and extending the driving piezoelectric element 11 ′ (not shown). (Arrow 83b). At the same time, the driving piezoelectric element 13 (not shown) is contracted and the driving piezoelectric element 13 ′ (not shown) is expanded to displace the driving beam 5d and the mass 7d in the direction toward the central base 2 ( Arrow 83d).

  Note that the displacement in the self-diagnosis mode is different from the vibration displacement in the vibration detection mode in which the yaw detection is performed, and means a simple displacement state that does not include vibration (a state in which it is stationary after being displaced in a specific direction). In this figure, the stationary state is shown.

  As described above, the drive beam 5a and the mass 7a are displaced in the direction away from the center base 2, and the drive beam 5d and the mass 7d located on the right side of the drive beam 5a in the drawing are displaced in the direction toward the center base 2. Further, when the driving beam 5b and the mass 7b located on the left side of the driving beam 5a in the drawing are displaced in the direction toward the central base 2, the corners 4a and 4b move to the driving beam 5a side. In other words, the corners 4a and 4b are displaced so as to approach the drive beam 5a. As a result, the detection beams 3a and 3b are also bent in a state of being displaced (arrows 84a and 84b) so as to approach the drive beam 5a. The bending of the detection beams 3a and 3b due to the displacement of the drive beam 5a causes the detection beam 3a to contract the detection piezoelectric element 14 (not shown) and the detection piezoelectric element 14 ′ (not shown) to expand. And the contraction / extension state is detected, and the detection piezoelectric element 15 ′ (not shown) contracts and the detection piezoelectric element 15 (not shown) expands at the detection beam 3b. An extension state is detected.

  Further, the drive beam 5c and the mass 7c are displaced in a direction away from the center base 2, the drive beam 5b and the mass 7b located on the right side of the drive beam 5c in the drawing are displaced in a direction toward the center base 2, and further, the drive beam When the drive beam 5d and the mass 7d located on the left side of the figure 5c are displaced in the direction toward the center base 2, the corners 4c and 4d move to the drive beam 5c side. In other words, the corners 4c and 4d are displaced so as to approach the drive beam 5c. As a result, the detection beams 3c and 3d are also bent in a state of being displaced (arrows 84c and 84d) so as to be close to the drive beam 5c. The bending of the detection beams 3c and 3d due to the displacement of the drive beam 5c causes the detection piezoelectric element 16 (not shown) to contract and the detection piezoelectric element 16 ′ (not shown) to expand at the detection beam 3c. The contraction / extension state is detected, and the detection beam 3d causes the detection piezoelectric element 17 ′ (not shown) to contract and the detection piezoelectric element 17 (not shown) to expand. An extension state is detected.

  In the self-diagnosis mode, the detection signal data from these piezoelectric elements is sent to the circuit board via the central base 2 or the like, and the data is arithmetically processed in a control circuit (not shown), for example. By comparing with the normal (initial) operation data at the time of product shipment, the detection beam and / or the piezoelectric element for detection is damaged or broken, and / or the circuit is shorted or the signal line is broken. It is possible to accurately grasp whether or not such a problem has occurred. The initial operation data of each piezoelectric element relating to the displacement of the detection beam or the like can be held in a storage means such as a memory inside / outside the package.

  Further, in the self-diagnosis mode, the magnitude of the detection signal of the detection piezoelectric element is compared between the set of detection beams 3a and 3b and the set of detection beams 3c and 3d, so that the drive beams 5a and 5c and / or Alternatively, it is also possible to estimate whether or not a failure such as a breakage or failure of each of the driving piezoelectric elements provided therein and / or a short circuit of the circuit or a disconnection of a signal line occurs. Similarly, by comparing the magnitude of the detection signal of the detection piezoelectric element between the set of detection beams 3b and 3c and the set of detection beams 3a and 3d, the drive beams 5b and 5d and / or It is also possible to infer the presence or absence of malfunctions such as breakage or failure of the provided driving piezoelectric element and / or short circuit or disconnection of signal lines.

  In this way, in the self-diagnosis mode, for example, the operation data of each piezoelectric element in a normal state at the time of product shipment is initially stored in advance, and each drive is compared with the data of the detection signal for diagnosis. It is possible to grasp the defects of the structural members related to the beam and / or the detection beam very easily.

  Similarly to the square angular velocity sensor element 1 in the first embodiment, even in the case of the angular velocity sensor elements having an even number of regular polygonal structures of 4 or more included in the second embodiment, they are positioned on the left and right of one drive beam. By displacing the drive beam with an opposite phase, it is possible to perform self-diagnosis of the drive beam, the detection beam, the piezoelectric element and the like. At this time, even if the even number of driving beams and masses are regularly and alternately displaced (alternately), the mechanical base is not mechanically moved with respect to the central base 2 that is the connection portion between the angular velocity sensor element and the package. Therefore, the durability of the sensor package can be kept high.

  FIG. 6 shows the angular velocity sensor element 30 according to the third embodiment operated in the self-diagnosis mode, and is connected to the detection beam, the drive beam, the drive piezoelectric element and / or the detection piezoelectric element, and further to those piezoelectric elements. FIG. 6 is a plan view for explaining an example of a method for self-diagnosis of defects such as breakage (including short circuit, disconnection, etc.) and malfunction of a circuit.

  Here, in the angular velocity sensor element 30 having the regular pentagonal structure according to the third embodiment, for example, first, the driving beams 35a, 35c, and 35d are displaced (arrows 85a, 85c, and 85d) in the direction toward the central base 2, and The piezoelectric elements in the detection beams 33a, 33b, 33c, and 33e except for the detection beam 33d in which the drive beams 35b and 35e are displaced in the direction away from the central base 2 (arrows 85b and 85e), and the displacement is difficult or difficult to occur. Are detected only (arrows 86a, 86b, 86c, 86e).

  In the self-diagnosis mode shown in FIG. 6, the drive beams 35b, 35d, and 35e are then displaced in the direction toward the center base 2, and the drive beams 35a and 35c are displaced in the direction away from the center base 2. Only the displacements of the piezoelectric elements of the detection beams 33a, 33b, 33c, and 33d are detected except for the detection beam 33e where the displacement does not occur or is difficult to occur. By sequentially performing such a multi-stage self-diagnosis step, it becomes possible to accurately measure the amount of displacement in all the detection beams of the angular velocity sensor element 30, and based on the measurement result, the drive beam, the detection beam In addition, the operation of the constituent members such as the piezoelectric elements can be diagnosed reliably and easily.

  Further, for example, first, the drive beam 35a is displaced in the direction toward the central base 2, and the drive beams 35b and 35e are displaced in the direction away from the central base 2, and the piezoelectric elements of the detection beams 33a and 33b are displaced. Only displacement is detected. Next, in the state where the driving beam 35b is displaced in the direction toward the central base 2 and the driving beams 35a and 35c are displaced in the direction away from the central base 2, only the displacement of the piezoelectric elements of the detection beams 33b and 33c is performed. You may make it detect. Even when such a plurality of self-diagnosis steps are included, since the time required for each step is extremely short, the operation time of the entire self-diagnosis mode can be set to a time that does not cause a problem in practice. it can.

  As described above, according to the self-diagnosis mode of the angular velocity sensor element, by displacing any two adjacent drive beams in the opposite direction, the detection beam disposed between them is intentionally bent, and the bending is performed. By detecting with the detecting piezoelectric element, it is possible to easily execute a self-diagnosis for the structural members such as the driving beam, the detecting beam, and the piezoelectric element.

  For example, in the case of a regular pentagonal structure such as the angular velocity sensor element 30 of the third embodiment, first, the displacement of the detection beam 33b is measured by displacing the drive beams 35a and 35b in opposite phases, and then A plurality of self-diagnosis steps such as measuring the displacement of the detection beam 33c by displacing the drive beams 35b and 35c in opposite phases may be performed. As described above, in the self-diagnosis mode of the angular velocity sensor element according to the present invention, an arbitrary drive beam among a plurality of drive beams is selectively displaced, the displacement of the detection beam corresponding to the drive beam is measured, and the detection is performed. Comparing the signal data with pre-stored initial operating data is included.

  Furthermore, for example, when the displacement of the detection piezoelectric element in the detection beam is detected in a state in which all the driving beams are displaced in the same phase (either in the direction approaching the center base 2 or in the direction away from the center base 2). Then, it can be diagnosed that the operation balance in the plurality of drive beams and the plurality of masses is out of the initial normal set value.

  Moreover, in the above-described self-diagnosis mode, when it is determined that some of the components such as the piezoelectric elements are defective or possibly, for example, the defect may be generated. By detecting only the detection signals from the detection beams including piezoelectric elements, and using the detection signals from the majority of other detection beams that are operating normally without any defects, the angular velocity sensor is used. The function as an element can be exhibited normally, and this can prevent impairing the reliability of the sensor package. Further, since it is possible to detect that such a defect has occurred at an early stage, replacement and maintenance of the angular velocity sensor element or the sensor package provided with the sensor can be appropriately performed at an appropriate time.

  In addition, the constituent material of the angular velocity sensor element according to the present invention is not particularly limited, and examples thereof include those made of silicon. In this case, the shape as shown in the figure is finely processed on a general wafer (silicon wafer or the like). (MEMS processing) It is possible to form integrally or collectively by a technique.

  Here, FIG. 7 ((A) to (G)) is a process diagram (process) showing an example of a state (procedure) in which a package (sensor package) including an embodiment of the angular velocity sensor element according to the present invention is manufactured. It is a flow diagram; schematic sectional drawing).

  In this case, first, a silicon thin film (substrate, sheet) 700 is prepared (FIG. 7A), and then one surface (the upper surface in the drawing) is formed, for example, lead zirconate titanate (PZT) having a piezoelectric effect. Coating is performed with a piezoelectric element material 710 such as an inorganic oxide or a polymer organic material (FIG. 7B). After that, the other surface (the lower surface in the drawing) of the silicon thin film 710 is etched so that a predetermined pattern is formed by an appropriate method (FIG. 7C). This forms a structure that later defines a gap below the angular rate sensor element. Further, predetermined patterning is performed on the piezoelectric element material 710 by a technique such as photolithography (FIG. 7D). As a result, a piezoelectric element structure (for convenience, the same reference numeral is attached and denoted as piezoelectric element 710) is formed.

  Then, the upper surface of the glass 720 to be the pedestal and the lower surface of the patterned silicon thin film 700 are fixed and connected by anodic bonding or the like (FIG. 7E), and then deep reactive ion etching (DRIE) or the like. The silicon thin film 700 is through-etched in a predetermined pattern from the front surface side to the back surface side where the piezoelectric element 710 is formed by the appropriate method (FIG. 7F). As a result, the silicon thin film 700 is fixed to the pedestal at a connection portion (corresponding to the central base 2 in each embodiment) with the glass 720 serving as the pedestal.

  Then, the structure shown in FIG. 7F is accommodated in a package 730 made of, for example, ceramic, and is fixed to the inner bottom wall of the package 730 through a glass 720 with a die bond material 740, for example. Further, a line 750 drawn from the central base 2 is formed by wire bonding or the like on a control circuit (not shown) provided in the package 730, and finally, the open end of the package 730 is covered with a lid 760. The joint between the two is sealed by, for example, seam welding (FIG. 7G). Thereby, the sensor package 790 in which the angular velocity sensor element is installed in the package 730 is obtained.

  The present invention is not limited to each of the above-described embodiments. As described above, various modifications (for example, appropriate contents of each embodiment are possible without departing from the spirit of the present invention). Combination) is possible. For example, it is possible to additionally provide piezoelectric elements provided on the drive beam and the detection beam not only on the upper surface of the angular velocity sensor element but also on the lower surface (that is, on the circuit board side), in which case the detection sensitivity of the angular velocity sensor element is further increased. Can be improved. Further, instead of the (positive) polygonal frame, a frame having a shape close to a circle or a frame having a circular shape may be used. When such a circular frame is used, it is assumed that the vibration using the driving piezoelectric element in each driving beam becomes unstable compared to a regular polygonal frame. Although the shape and mass of each auxiliary mass connected with the beam interposed therebetween may be adjusted as appropriate, a polygonal frame is preferable from the viewpoint of such vibration stability.

  DESCRIPTION OF SYMBOLS 1,20,30 ... Angular velocity sensor element (angular velocity sensor), 2 ... Center base part, 3, 23, 33 ... Detection beam, 4, 24, 34 ... Corner, 5, 25, 35 ... Drive beam, 6, 26, 36 ... Frame, 7, 27, 37 ... Mass (mass), 9, 29, 39 ... Space, 10, 11, 12, 13 ... Drive piezoelectric element, 14, 15, 16, 17 ... Detection piezoelectric element, 70, 71 ... auxiliary mass, 72 ... top side, 73, 74 ... oblique side, 75 ... bottom side, 77 ... connection part, 80, 81, 82, 83, 84, 85, 86 ... vibration (displacement), 790 ... sensor package , Α... Element center, β... Rotation (in the reference numerals of each member, the subscripts “a” and “b” are omitted as appropriate for convenience of explanation).

Claims (8)

A frame having a polygonal shape, and a drive unit having a plurality of mass bodies connected to the frame;
A detection unit connected to the frame;
An angular velocity sensor comprising: In the drive unit, each side of the frame body is displaced or vibrated in the same phase in the polygonal surface direction.
The angular velocity sensor according to claim 1. In the drive unit, at least two sides adjacent to each other of the sides of the frame body are displaced or vibrated in opposite phases in the polygonal surface direction.
The angular velocity sensor according to claim 1. The frame has a plurality of drive beams corresponding to the sides of the polygonal shape,
The detection unit has a plurality of detection beams provided so as to connect a base portion located in an inner region of the polygonal shape and each vertex of the polygonal shape,
The angular velocity sensor according to claim 1. Each of the plurality of mass bodies is provided in each of the plurality of drive beams.
The angular velocity sensor according to claim 4. Each of the plurality of driving beams has at least a pair of driving piezoelectric elements,
Each of the plurality of detection beams has at least a pair of detection piezoelectric elements.
The angular velocity sensor according to claim 4 or 5. The frame has a polygonal shape having an even number of sides of 4 or more;
The angular velocity sensor according to claim 1. The frame has a polygonal shape having odd sides of 3 or more,
The angular velocity sensor according to claim 1.

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