JP2008096138A - Angular velocity sensor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tuning-fork-type angular velocity sensor capable of individually adjusting vibration characteristics of a plurality of vibrating arms and provide its manufacturing method. <P>SOLUTION: With vibrations of other arm parts 12B except an arm part 12A to be adjusted mechanically restrained, vibration characteristics of the arm parts 12A and 12B are adjusted. In this state, coupled vibrations are not generated between the arm parts 12A and 12B, and the arm part 12A to be adjusted vibrates in a form of natural vibrations according to its external shape, piezoelectric characteristics, etc. It is thereby possible to individually adjust vibration characteristics such as a vibrating direction, a resonance frequency, etc. of the arm part 12A. Since it is possible to highly accurately adjust vibration characteristics of each of the arm parts 12A and 12B, it is possible to manufacture angular velocity sensors provided with a vibrator having expected vibration characteristics. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an angular velocity sensor manufacturing method and an angular velocity sensor used for, for example, camera shake detection of a video camera, motion detection in a virtual reality device, direction detection in a car navigation system, and more specifically, a tuning fork type vibrator. The present invention relates to an angular velocity sensor manufacturing method and an angular velocity sensor.

  Conventionally, as a commercial angular velocity sensor, a cantilever beam or a vibrating cantilever type vibrator or tuning fork type vibrator of a cantilever beam is vibrated at a predetermined resonance frequency, and the Coriolis force generated by the influence of the angular velocity is applied to the piezoelectric element. A so-called vibration-type gyro sensor that detects an angular velocity by detecting the angle is widely used. This type of vibration type gyro sensor has advantages such as simple mechanism, short start-up time, and low cost, and can be installed in electronic devices such as video cameras, virtual reality devices, car navigation systems, etc. It is used as a sensor for camera shake detection, motion detection, and direction detection.

  The vibration type gyro sensor is required to be downsized and improved in accordance with downsizing and high performance of electronic devices to be mounted. For example, in order to increase the functionality of electronic devices, there is a demand for downsizing by mounting on the same collective substrate in combination with various sensors used for other applications. In order to reduce the size, it is necessary to use a processing technique called MEMS that forms a structure using a single crystal substrate such as silicon (Si) and a thin film formation process and a photolithography technique used in the semiconductor manufacturing field. It has become common (see, for example, Patent Documents 1 and 2).

  In addition, a piezoelectric material having a function of an inverse piezoelectric effect that generates a strain from an electrical signal and a piezoelectric effect that generates an electrical signal from a strain is used in a gyro sensor, and the vibrator is driven to resonate. When the sensor rotates, a Coriolis force acts on the gyro sensor, a force perpendicular to the vibration direction of the vibrator is generated, and a function of converting a distortion caused by the force into an electrical signal as an angular velocity is realized.

  By the way, since the cross-sectional shape of the vibrator formed by MEMS processing may deviate from the ideal shape as the vibrator, the vertical and horizontal directions of the vibration surface in the mechanical vibration of the vibrator after the sensor element is formed. It is necessary to adjust the difference in resonance frequency. For example, Patent Document 1 describes various adjustment methods for the vibration state of a vibrator.

  On the other hand, in a gyro sensor having a tuning fork type vibrator described in Patent Document 2 or the like, a coupled vibration mode is formed between two or more vibration arms. For this reason, the center of gravity formed between a series of vibrating arms is different even if the vibrating arm alone is out of the ideal shape from the cross section of the arm and the vibrating surface is shifted like a cantilevered gyroscope. The moving vibration mode is degenerate and the center of gravity does not move.In other words, vibrations other than the horizontal plane with respect to the plane on which a series of vibrators are formed are unlikely to occur. There wasn't.

JP-A-2005-241382 JP 2006-17569 A

  In automobiles and portable electronic devices that use a small gyro sensor, the power quality provided to the gyro sensor is not necessarily an ideal power waveform. In many cases, AC signals generated from electrical components are mixed. When such a power supply is provided to a tuning-fork type gyro sensor that is not mechanically adjusted, the mixed AC signal has a frequency that becomes a sideband by superimposing an AC signal that resonates and drives the vibrator inside the gyro sensor. The formation causes a deviation in the driving frequency of the vibrator.

  The vibrator is a tuning fork vibrator formed by forming a piezoelectric film on the surface of the Si substrate and performing shape processing on the Si substrate by MEMS technology, and a vibration state serving as a fundamental mode is the piezoelectric film. When vibration excitation is performed in the direction along the formation surface, the rigid center of vibration excitation by the piezoelectric film is shifted from the center of gravity of the vibrator.

  As described above, when the vibrator is driven by vibration excitation along the piezoelectric film in a state where the drive frequency is shifted, the vibration surface of the resonator in the resonance state is easily shifted, and as a result, an angular velocity is generated. The detection output fluctuates even in the absence of noise, and there is a risk that noise will increase significantly. For this reason, in a tuning fork type gyro sensor, it is desirable to perform mechanical adjustment of the vibrator as in the case of a cantilevered sound piece type gyro. However, since a coupled vibration is generated between a plurality of vibrating arms, There is a problem that it is difficult to individually adjust the arms.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a method for manufacturing a tuning fork type angular velocity sensor and an angular velocity sensor capable of individually adjusting the vibration characteristics of a plurality of vibrating arms.

  In solving the above problems, the manufacturing method of the angular velocity sensor according to the present invention provides a drive for excitation via a piezoelectric film on one surface of a plurality of arm portions integrally extending from the base portion in substantially the same direction. A method of manufacturing an angular velocity sensor in which an electrode and a detection electrode for detecting an angular velocity are formed, each of which independently adjusts the vibration characteristics of the arm portion, and other than one arm portion to be adjusted The vibration characteristic of the one arm portion is adjusted in a state where the vibration of the arm portion is mechanically restrained.

  The plurality of arms constitute a tuning fork type vibrator. In the plurality of arm portions, vibration is excited by the inverse piezoelectric effect of the piezoelectric film generated when an AC signal having a driving frequency is applied to the driving electrode. The detection electrode detects a vibration component in a direction perpendicular to the vibration surface generated when an angular velocity is generated by the piezoelectric effect of the piezoelectric film, and outputs this as an angular velocity signal.

  In the present invention, adjustment of the vibration characteristics of each arm portion is performed in a state where vibrations of other arm portions other than one arm portion to be adjusted are mechanically constrained. In this state, there is no coupled vibration between the arm portions, and the arm portion to be adjusted vibrates in a specific vibration form corresponding to its outer shape, piezoelectric characteristics, and the like. This makes it possible to individually adjust the vibration characteristics such as the vibration direction of the arm portion and the resonance frequency. In addition, the vibration characteristics of each arm can be adjusted with high accuracy, and an angular velocity sensor including a vibrator having the desired vibration characteristics can be manufactured.

  For mechanical restraint of the arm part, a method of attaching an elastic fixing tool to the arm part can be employed. A big force is not required for restraint. By adding lightly to the arm part, the resonance vibration of the arm part can be prevented. As a result, mechanical coupling between the arm portions can be prevented, and the vibration characteristics of each arm portion can be adjusted individually.

  The vibration characteristics of the arm part include the vibration direction, vibration frequency, detuning degree, and the like of the arm part. The vibration direction of the arm portion is a direction parallel to the surface on which the piezoelectric film is formed, but is not limited thereto, and may be a direction perpendicular to the surface on which the piezoelectric film is formed. The vibration state of the arm part, for example, the vibration direction can be monitored by a detection signal from the detection electrode, a displacement measurement of the vibration part of the arm part, or the like. The adjustment of the vibration characteristics of the arm portion can be performed, for example, by external processing for the arm portion using a laser processing apparatus.

  According to the present invention, it is possible to individually adjust the vibration characteristics of a plurality of vibration arms. As a result, it is possible to adjust the vibration characteristics of each arm portion with high accuracy, and an angular velocity sensor including a vibrator having desired vibration characteristics can be manufactured.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view showing a schematic configuration of a tuning-fork type angular velocity sensor (vibration gyro sensor) 10 according to an embodiment of the present invention. The angular velocity sensor 10 of the present embodiment includes a base portion 11 and two arm portions 12A and 12B integrally extending from the base portion 11 in substantially the same direction (y-axis direction). These base portion 11 and arm portions 12A and 12B are manufactured using a MEMS processing technique, and a piezoelectric functional layer and various lead wiring portions, which will be described later, are formed on a single crystal substrate having no piezoelectric characteristics such as a Si (silicon) wafer. After being formed, the angular velocity sensor 10 is configured by cutting into a predetermined shape using dry etching and dicing.

  The arm portions 12A and 12B constitute a vibrator of the angular velocity sensor 10, and two are formed in the illustrated example, but may be three or more. Drive electrodes 13a1 and 13a2 for excitation and detection electrodes 14a1 and 14a2 for angular velocity detection are formed on one surface of one arm portion 12A, respectively. Drive electrodes 13b1 and 13b2 for excitation and detection electrodes 14b1 and 14b2 for angular velocity detection are formed on one surface of the other arm portion 12B, respectively.

  The drive electrodes 13a1 and 13a2 and the drive electrodes 13b1 and 13b2 are arranged on the arm portions 12A and 12B so as to sandwich the detection electrodes 14a1 and 14a2 and the detection electrodes 14b1 and 14b2, respectively. The detection electrodes 14a1 and 14a2 and the detection electrodes 14b1 and 14b2 are respectively formed at symmetrical positions with respect to the axial centers of the arm portions 12A and 12B having a square cross section. The drive electrode 13a1 and the drive electrode 13a2 are disposed outside and inside the detection electrodes 14a1 and 14a2, respectively, at symmetrical positions with respect to the axis of the arm portion 12A. The drive electrode 13b1 and the drive electrode 13b2 are arranged outside the detection electrodes 14b1 and 14b2. On the inner side, they are arranged at symmetrical positions with respect to the axis of the arm portion 12B.

  2A is a cross-sectional view in the direction [2]-[2] in FIG. FIG. 2B is a schematic cross-sectional view of the piezoelectric functional layers 15A and 15B. The drive electrodes 13a1, 13a2, 13b1, 13b2 and the detection electrodes 14a1, 14a2, 14b1, 14b2 are formed on the piezoelectric films 16A, 16B provided on the arm portions 12A, 12B via the base electrode film 17. . Hereinafter, the base electrode film 17, the piezoelectric films 16A and 16B, the drive electrodes 13a1, 13a2, 13b1, and 13b2, and the detection electrodes 14a1, 14a2, 14b1, and 14b2 are collectively referred to as piezoelectric functional layers 15A and 15B.

  In this embodiment, the formation regions of the piezoelectric functional layers 15A and 15B are directions (z-axis direction) orthogonal to the extending direction (y-axis direction) of the arm portions 12A and 12B and the arrangement direction (x-axis direction), respectively. ) On the surface of each of the arm portions 12A and 12B having a normal line. In addition, the piezoelectric functional layers 15A and 15B may be formed on the outer surface side of the arm portions 12A and 12B having a normal line in the x-axis direction.

  Here, the base electrode film 17 is composed of a laminated film of Ti (titanium) and Pt (platinum) formed on the Si substrate by a sputtering method, and between the arm portions 12A and 12B as a common electrode film in the piezoelectric functional layers 15A and 15B. Is formed. The piezoelectric films 16A and 16B are formed, for example, by RF sputtering a PZT (lead zirconate titanate) target in an oxygen atmosphere. The drive electrodes 13a1, 13a2, 13b1, 13b2, and the detection electrodes 14a1, 14a2, 14b1, 14b2 are formed by patterning a Pt film formed on the piezoelectric films 16A, 16B into each electrode shape using a photolithography technique. Is done. After the electrode pattern is formed, the piezoelectric films 16A and 16B are also patterned in accordance with the shape of the upper electrode, but the present invention is not limited to this. Then, the wiring connected to the drive electrodes 13a1, 13a2, 13b1, 13b2, the detection electrodes 14a1, 14a2, 14b1, 14b2, and a part of the base electrode film 17 exposed from the wiring extraction part 26 on the arm part 12B. A group 25 and lands 23a1, 23a2, 23b1, 23b2, 24a1, 24a2, 24b1, 24b2, and 27 for electrode extraction are formed on the base 11, respectively. The angular velocity sensor 10 is electrically connected to a wiring board (not shown) through the land by a flip chip bonding method, a wire bonding bonding method, or the like.

  In the angular velocity sensor 10 of the present embodiment having the above-described configuration, the base electrode film 17 is connected to the GND (ground) potential, and the drive electrode 13a1 of the arm portion 12A and the drive electrode 13b1 of the arm portion 12B are connected. Then, an AC signal as a drive signal is supplied, and a drive signal having an opposite phase to the AC signal is supplied to the drive electrode 13a2 of the arm portion 12A and the drive electrode 13b2 of the arm portion 12B. As a result, as shown in FIG. 3A, the piezoelectric portions of the drive electrodes 13a1 and 13b1 expand and the piezoelectric portions of the drive electrodes 13a2 and 13b2 contract at a certain moment, so that the two arm portions 12A and 12B are deformed in the closing direction. To do. At another moment, as shown in FIG. 3B, the piezoelectric portions of the drive electrodes 13a1 and 13b1 contract and the piezoelectric portions of the drive electrodes 13a2 and 13b2 extend, so that the two arm portions 12A and 12B are deformed in the opening direction. To do. As a result of this operation occurring at the resonance frequency of the vibrator, the vibrator is amplified in deformation by the resonance magnification of the vibrator, and the arms 12A and 12B are opened and closed in the x-axis direction.

  Further, when rotation is applied about the extending direction (y-axis direction) of the arm portions 12A and 12B in this state, a Coriolis force is generated in the vibrator. For example, when the rotation is applied in a predetermined direction, when the arm portions 12A and 12B operate in the closing direction, as shown in FIG. 4A, the arm portion 12A has a downward direction (−z direction) and the arm portion 12B has a An upward force (+ z direction) is generated. When the arms 12A and 12B operate in the opening direction, as shown in FIG. 4B, the arm 12A has an upward force (+ z direction) and the arm 12B has a downward force (−z direction). Each occurs. As a result, the two arm portions 12A and 12B generate a motion as shown in FIG. 5, and the sum signal of the detection electrode 14a1 and the detection electrode 14a2 generated in synchronization with this motion, the detection electrode 14b1 and the detection electrode With the sum signal of 14b2, an output proportional to the force generated in the vertical direction of the vibrator, that is, the angular velocity is obtained.

  In the angular velocity sensor 10 of the present embodiment, the piezoelectric functional layers 15A and 15B are respectively formed on one surface of the arm portions 12A and 12B. Therefore, the vibration of each arm portion at this time is as shown in FIG. become. FIG. 6 shows the arm portion 12A. For example, when one drive electrode 13a1 is extended and the other drive electrode 13a2 is contracted, the stress S1 generated from the drive electrode 13a1 side is obliquely lower right when observed in the cross section of the arm portion 12A, and the drive electrode 13a2 The stress S2 generated from the side is in the diagonally upper right direction. As a combination of the two stresses S1 and S2, a rightward excitation driving force S is generated in the arm portion 12A. At this time, in the same description, a leftward excitation driving force is generated in the arm portion 12B.

  Here, there is no particular problem in the case where the cross sections of the arm portions 12A and 12B as the vibrator are stably formed in a quadrangular shape as shown in FIG. 6, but ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching). When the shape processing of the arm portions 12A and 12B is performed using a dry etching method such as the above, the cross-sectional shape of the arm portions 12A and 12B is not necessarily formed in a right-angled square shape, for example, schematically shown in FIG. It becomes a distorted square shape as shown. Therefore, the vibrator having the shape shown in FIG. 7 has an excitation driving force S0 in an oblique direction, and the excitation direction is easily displaced in this direction.

  Further, as shown in FIG. 8, when the cross-sectional shape of the vibrator is a regular square whose aspect ratio is slightly deviated from 1, the longitudinal resonance frequency Fv and the transverse resonance frequency Fh are set apart by about several hundred Hz. Is done. In the present embodiment, the lateral resonance frequency Fh corresponds to the drive frequency of the vibrator, and the longitudinal resonance frequency Fv corresponds to the angular velocity detection frequency. When the vertical force is applied during application of the angular velocity, it is designed to excite vibration that shifts in the vertical direction in synchronization with the horizontal direction, so that the angular velocity can be detected. Fv and Fh are separated by only a few hundred Hz, and the rigid center R of the driving force exists almost on the surface even though the center of gravity G of the vibrator is at the center of the cross section, and the positions of both are greatly displaced. Therefore, the vibration in the vertical direction is very easily excited with respect to the shift of the lateral resonance frequency Fh, and the vibration surface is easily shifted by the modulation of the drive signal frequency.

  A tuning fork vibrator generally has a vibration mode in which a vibration center is degenerated as a vibration mode except for a mode in which a plurality of vibration arms are mechanically coupled to form coupled vibration, and the position of the center of gravity determined by the combination of the plurality of vibration arms does not move. It exists stably. For this reason, for example, when the cross-sectional shape of the arm portions 12A and 12B is distorted into a parallelogram shape as shown in FIG. 9, the direction of the distortion is linear between the two arm portions 12A and 12B as shown in FIG. 9B. When symmetric (symmetric with respect to the z-axis), the arms 12A and 12B vibrate in the horizontal direction (x-axis direction) in the coupled vibration mode even though the individual vibration directions are oblique. To do. 9A, when the cross-sectional distortion direction is the same between the two arm portions 12A and 12B, the vibration direction in the coupled vibration mode is substantially the same as the individual vibration direction.

  In the case of FIG. 9A, as the drive frequency deviates from Fh and approaches Fv, the vibration surface greatly deviates, the output as a gyro changes, and noise is generated that changes the output even when no angular velocity is applied. Also in the case of FIG. 9B, if the drive frequency deviates from Fh, the vibration becomes unstable, resulting in sensitivity instability and noise generation. Note that the fluctuation of the driving frequency Fh occurs due to a sideband generated when a disturbance signal is mixed into the driving signal. For example, when the frequency of the disturbance signal is Fa, a sideband wave of Fh ± Fa is formed. Under the design condition of Fh> Fv, the resonance frequency of Fh−Fa is close to Fv, and under the design condition of Fh <Fv, It approaches Fv at the resonance frequency of Fh + Fa.

  As described above, the angular velocity sensor having the excitation direction in the x-axis direction can be mechanically adjusted in the same manner as the cantilever type vibrating sound piece type in which the piezoelectric film is formed on the surface of the Si substrate. In the case shown in FIG. 9A, since the arm portion 12A and the arm portion 12B are coupled, the vibration of the arm portion 12A is affected by the vibration of the arm portion 12B even if only the arm portion 12A is mechanically adjusted. Therefore, even if the vibration surface of the arm portion 12A is observed, it cannot be adjusted appropriately. Further, in the case as shown in FIG. 9B, although the vibration direction of the individual arm is deviated from the horizontal plane of the vibrator, when the two arm portions 12A and 12B are coupled and vibrated, the vibration surface is changed. Since it becomes a horizontal surface, there is no monitoring element necessary for adjustment, and the arm portions 12A and 12B cannot be mechanically adjusted.

Therefore, in this embodiment, the vibration characteristics of the arm portions 12A and 12B are adjusted by the following method.
That is, in the present embodiment, the vibration characteristics of the arm portions 12A and 12B are adjusted independently, and vibrations of other arm portions other than one arm portion to be adjusted are mechanically constrained. The vibration characteristic of the one arm portion is adjusted.

  Specifically, as shown in FIG. 10, when adjusting the arm portion 12 </ b> A, the arm portion 12 </ b> B restrains vibration by an elastic fixing tool 30. The restraining force of the arm part 12B by the fixing tool 30 does not have to be a large force, and it is sufficient that a load that can remove the resonance condition of the arm part 12B can be applied to the arm part 12B. If the fixture 30 is a structure which contacts the arm part 12B, the fixing structure and attachment position will not be restrict | limited in particular. By this method, the mechanically coupled operation condition is not established between the two arm portions 12A and 12B, and therefore the arm portion 12A can be vibrated with its inherent vibration characteristics.

  FIG. 11 is a diagram for explaining a process of adjusting the vibration characteristics of the arm portion 12A. As shown in FIG. 11A, with the fixture 30 attached to the arm portion 12B, a drive signal is input to the drive electrodes 13a1 and 13a2 of the arm portion 12A to resonately drive the arm portion 12A. At this time, the arm portion 12A vibrates with a unique vibration characteristic due to its cross-sectional shape and the like. Then, while monitoring the vibration direction of the arm portion 12A based on the output signals of the detection electrodes 14a1 and 14a2, as shown in FIG. 11B, the laser beam is irradiated from the side of the arm portion 12A to form the outer shape. The vibration direction of the portion 12A is adjusted in the horizontal direction (direction parallel to the piezoelectric film forming surface). Note that when the vibration direction is the horizontal direction, the sum signal of the outputs of the detection electrodes 14a1 and 14a2 becomes 0. Therefore, the outer shape machining position and the machining amount with respect to the arm portion 12A are adjusted so that the detection signal becomes 0.

  After the adjustment of the arm portion 12A is completed, the fixture 30 is removed from the arm portion 12B, and this time, the fixture 30 is attached to the arm portion 12A to adjust the vibration characteristics of the arm portion 12B. FIG. 13 shows a process of adjusting the vibration characteristics of the arm portion 12B. Adjustment of the arm portion 12B is performed while inputting a drive signal to the drive electrodes 13b1 and 13b2 and causing the arm portion 12B to resonate similarly to the adjustment of the arm portion 12A. At this time, since the vibration of the arm portion 12A is restrained by the fixture 30, the arm portion 12B vibrates with a unique vibration characteristic. Then, using the laser trimming technique as described above, adjustment is made so that the vibration direction of the arm portion 12B becomes the horizontal direction.

  When adjusting the vibration characteristics of the arm portion 12B, the arm portion 12A has already been adjusted. Therefore, even if the coupled vibration with the arm portion 12A is performed, the arm portion 12B vibrates with its own vibration characteristics. Tend to. Therefore, it is possible to adjust the arm portion 12B without attaching the fixture 30 to the arm portion 12A. When high-precision adjustment is required, it is preferable to restrain the vibration of the arm portion 12A even when adjusting the arm portion 12B.

  In this adjustment step, the degree of detuning (difference between the longitudinal resonance frequency and the transverse resonance frequency) and the resonance frequency may be adjusted at the same time. As a method for adjusting the resonance frequency, the tip portion of the arm portion is laser processed when the frequency is increased, and the root portion of the arm portion is laser processed when the frequency is decreased. As an adjustment method when the resonance frequency is different between the arm portions, the resonance frequency of the arm portion 12A and the resonance frequency of the arm portion 12B are individually measured in advance so that the resonance frequencies of the respective arm portions substantially coincide with each other. For example, a laser is applied to the base part of the arm part on the arm part on the high frequency side, and a laser is applied to the tip part of the arm part on the arm part on the low frequency side.

  As described above, the vibration characteristics of the arm portions 12A and 12B are adjusted. According to the present embodiment, the vibration characteristics such as the vibration direction, the degree of detuning, and the resonance frequency of the arm parts 12A and 12B can be individually adjusted. Therefore, the vibration characteristics of the arm parts 12A and 12B can be adjusted with high accuracy. Can be done. As a result, it is possible to manufacture a noise-resistant angular velocity sensor including a vibrator having desired vibration characteristics.

  FIGS. 13A and 13B illustrate a method of detecting horizontal vibration of the arm portion 12A using a horizontal vibration monitor that optically detects displacement of the vibration surface (upper surface) of the arm portion 12A as another embodiment. FIG. A laser displacement meter can be used as the horizontal vibration monitor. Also in the present embodiment, the vibration of the other arm portion 12B is restrained by the fixture 30 when adjusting one arm portion (arm portion 12A in the illustrated example). When the individual vibration direction of the arm 12A before the adjustment is oblique, the output of the horizontal vibration monitor fluctuates periodically. The arm portion 12B is irradiated with laser light so that this fluctuation becomes zero, and the vibration direction is adjusted to the horizontal direction (FIG. 12B). In this case as well, it is of course possible to refer to the output signal from the detection electrode of the arm portion.

  Furthermore, as another embodiment, more preferably, when the drive frequency of the arm portion is swept, the frequency component of Fv corresponding to the detection frequency is smaller than the frequency component of Fh corresponding to the drive frequency. You may make it adjust the vibration characteristic of each arm part so that the frequency component of Fv may become the minimum. Accordingly, since the displacement to the detection frequency Fv due to the change in the drive frequency can be suppressed without strictly adjusting the vibration direction of the arm portion in the horizontal direction, it is possible to suppress the generation of noise.

  As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to this, A various deformation | transformation is possible based on the technical idea of this invention.

  For example, in the above embodiment, the angular velocity sensor having two vibration arms has been described as an example. However, the number of the arm portions is not limited to two, and the angular velocity sensor having three or more arm portions is also applicable. It is possible to apply. In this case, when adjusting the vibration of one arm part, the vibrations of the other two arm parts are restrained.

  In the above embodiment, the excitation direction of each arm portion is a direction parallel to the piezoelectric film formation surface (x-axis direction in FIG. 1), and the detection direction is perpendicular to the piezoelectric film formation surface. Although an example in which the present invention is applied to an angular velocity sensor having a vibrator having a direction (z-axis direction) has been described, the present invention is not limited to this, and the excitation direction is a direction perpendicular to the surface on which the piezoelectric film is formed. The present invention can also be applied to an angular velocity sensor having a vibrator whose direction is parallel to the formation surface of the piezoelectric film.

It is a top view which shows schematic structure of the angular velocity sensor by embodiment of this invention. It is a [2]-[2] line direction sectional view in Drawing 1, and a schematic structure figure of a piezoelectric functional layer. It is a principal part front view for demonstrating the excitation operation | movement of the arm part of the angular velocity sensor of FIG. It is a principal part front view for demonstrating the angular velocity detection operation | movement of the angular velocity sensor of FIG. It is a principal part front view explaining the vibration state of the arm part at the time of angular velocity application. It is a principal part front view explaining the excitation drive principle of an arm part. It is a principal part front view explaining the change of the excitation direction by the cross-sectional shape of an arm part. It is a principal part front view explaining the gravity center position and rigid center position of an arm part. It is a principal part front view explaining the separate vibration direction and coupled vibration direction by the difference in the cross-sectional shape of an arm part. It is a top view explaining the adjustment method of the vibration characteristic of the angular velocity sensor by embodiment of this invention. It is a principal part front view explaining the adjustment method of the vibration characteristic of the angular velocity sensor by embodiment of this invention. It is a principal part front view explaining the adjustment method of the vibration characteristic of the angular velocity sensor by embodiment of this invention. It is a principal part front view explaining the adjustment method of the vibration characteristic of the angular velocity sensor by other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Angular velocity sensor, 11 ... Base, 12A, 12B ... Arm part, 13a1, 13a2, 13b1, 13b2 ... Drive electrode, 14a1, 14a2, 14b1, 14b2 ... Detection electrode, 15A, 15B ... Piezoelectric functional layer, 16A, 16B ... Piezoelectric film, 17 ... underlying electrode film, 30 ... fixing tool

Claims (8)

Manufacturing method of angular velocity sensor in which drive electrode for excitation and detection electrode for angular velocity detection are respectively formed on one surface of a plurality of arm portions integrally extending from the base portion in substantially the same direction via a piezoelectric film Because
While adjusting the vibration characteristics of the arm part independently,
A method of manufacturing an angular velocity sensor, wherein the vibration characteristics of one arm portion are adjusted in a state where vibrations of other arm portions other than the one arm portion to be adjusted are mechanically constrained. The method of manufacturing an angular velocity sensor according to claim 1, wherein an elastic fixing tool is attached to the other arm portion to restrain vibration of the other arm portion. The method of manufacturing an angular velocity sensor according to claim 1, wherein a vibration direction of the arm portion is adjusted to a direction parallel to a formation surface of the piezoelectric film. 2. The method of manufacturing an angular velocity sensor according to claim 1, wherein a vibration direction of the arm portion is adjusted in a direction perpendicular to a formation surface of the piezoelectric film.   The method of manufacturing an angular velocity sensor according to claim 1, wherein the vibration characteristics of the arm portion are adjusted based on a detection signal from the detection electrode. The method of manufacturing an angular velocity sensor according to claim 1, wherein the adjustment of the vibration characteristics of the arm portion is performed while optically detecting a displacement of a vibration surface of the arm portion. The method for manufacturing an angular velocity sensor according to claim 1, wherein the adjustment of the vibration characteristics of the arm portion is performed by external processing on the arm portion. The base,
A plurality of arm portions integrally extending from the base portion in substantially the same direction;
A piezoelectric film formed on one surface of the arm part;
An angular velocity sensor comprising a drive electrode for excitation and a detection electrode for angular velocity detection respectively formed on the piezoelectric film,
One of the plurality of arm portions vibrates in a direction parallel or perpendicular to the surface on which the piezoelectric film is formed when mechanically restraining vibrations of other arm portions other than the one arm portion. An angular velocity sensor characterized by

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