JP2014089049A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity sensor capable of preventing vibration of an angular velocity detection element from being leaked to the outside.SOLUTION: Vibration occurring in an angular velocity detection element 3 can be suppressed by a balancer 14 having inertia, a twisted spring portion 13 holds the angular velocity detection element 3 and the balancer 14 while damping vibration, and thereby vibration of an angular velocity detection element 3 can be prevented from being leaked to the outside. Furthermore, optimization of materials and dimensions of the balancer 14 and the twisted spring portion 13 can prevent vibration occurring in the angular velocity detection element 3 from being leaked to the outside.

Description

  The present invention relates to an angular velocity sensor represented by a piezoelectric vibration type yaw rate sensor.

  In recent years, many devices that detect minute vibrations using piezoelectric elements have been utilized. As one of them, for example, by detecting very weak vibration and displacement caused by Coriolis force generated when rotation is applied to the vibrating mass body through the piezoelectric element, Examples thereof include an angular velocity sensor such as a piezoelectric vibration type yaw rate sensor and a gyro sensor that can detect and measure a rotational operation, that is, a rotational angular velocity. Among these, as a long-life, low-cost, compact and lightweight angular velocity sensor, it is equipped with an angular velocity detecting element having a plurality of vibrating arms facing each other across the base, and one vibrating arm, that is, the driving arm is driven in a plane. An H-type angular velocity sensor that detects vibration / displacement generated in the direction orthogonal to the driving direction by the Coriolis force by the other vibrating arm, that is, the detection arm has been proposed or put into practical use.

  However, in order to realize an extremely small and highly sensitive angular velocity sensor, it is necessary to obtain a large displacement using the resonance frequency of each vibrating arm. In addition, for example, an angular velocity sensor used for detecting the attitude behavior of an automobile requires high performance in terms of vibration resistance and impact resistance.

  The angular velocity detecting element vibrates in a complicated manner by acting at least two orthogonal vibration modes of an excitation vibration for obtaining a Coriolis force and a detection vibration for detecting the Coriolis force. It is desirable that vibrations of these angular velocity detection elements are originally vibrated in a closed system in the elements. However, in the actual angular velocity detection element, unnecessary vibrations caused by processing asymmetry, vibrations used for excitation and detection, etc. Depending on the mode shape of the mode, it is inevitable that the vibration of the angular velocity detection element leaks to the outside of the element. If the material is supported by a low-rigidity material such as silicone rubber in order to reduce external vibrations, the vibration-resistant characteristics against the unnecessary vibration applied from the outside and the shock-resistant performance are deteriorated.

  Patent Document 1 shows an example of a conventional H-type angular velocity sensor. There is an H-shaped vibrating arm, and there are a driving arm for exciting and a detecting arm for detecting a vibration state when vibrating. There is a support beam that supports the vibrating arm, and four vibrating arms including two drive arms and two detection arms are provided in an H shape so as to protrude from the support beam. The connecting piece fixes and supports the support beam, and has strain detection means for detecting the degree of strain of the support beam when the vibrating arm vibrates.

  The operation of the conventional H-type angular velocity sensor configured as described above will be described. First, when the driving arm for exciting one side is vibrated along the X axis which is an axis perpendicular to the longitudinal direction of the vibrating arm, the detection arm for detecting the vibration state is orthogonal to the X axis. A vibration state when vibrating along the Z-axis direction is detected. At this time, strain detection means provided on the support beam detects the degree of strain of the support beam. Patent Document 1 discloses a technique in which the strain detection means is disposed on both sides of the protruding portion of the connecting piece in the support beam.

  Patent Document 2 shows an example of an angular velocity sensor of a package on which a tuning fork vibrator is mounted. The package is mounted with a tuning fork vibrator that is attached directly or via an electronic component and some member. When the tuning fork vibrator vibrates, it is transmitted to the package, and vibration leakage to the outside may occur. In particular, it has been pointed out that when a lightweight material such as ceramics is used as a package material, there is a problem that the characteristics of the tuning fork vibrator are not stable due to vibration leakage. In Patent Document 2, as a means for solving this problem, inertia when a tuning fork vibrator is arranged in a package so that the width direction of the tuning fork vibrator is in the long side direction of the package and the tuning fork vibrator is held in the package is disclosed. A technique for increasing the size is disclosed.

  Patent Document 3 shows an example of an angular velocity sensor that includes a support portion on which a tuning fork vibrator is mounted, and a vibration isolation portion that connects the support portion and the mounting portion. In an angular velocity sensor having a vibrator, the vibration of the vibrator leaks to the outside through other components. For this reason, when the angular velocity sensor is mounted on a system or the like, the vibration state may change, and the characteristics of the vibrator may change. In Patent Document 3, when the tuning fork vibrator vibrates, the vibration of the vibrator is reduced by the moment of inertia of the weight of the support portion. Furthermore, a method for preventing external vibration leakage and reducing the influence of external vibration on the vibrator is disclosed by holding the support portion with a low-rigidity member such as silicone rubber called a vibration isolation portion.

JP-A-8-334332 JP 2007-71672 A JP 2008-8634 A

  However, in the conventional configuration of Patent Document 1, the support beam that directly affects the movement of the vibrating arm is directly connected with high rigidity using a connecting piece. doing. Specifically, since the linear expansion coefficient between the connecting piece and the package on which the angular velocity detecting element is mounted cannot be made to match completely, the length of the connecting piece and the package when the temperature applied to the sensor changes, such as a change in outside air temperature. The amount of elongation differs, and this changes the natural frequency and changes the characteristics. Also, no countermeasures against external vibration leakage are taken into consideration.

  In the conventional configuration of Patent Document 2, the inertia is increased by aligning the width direction of the vibrator with the long side direction of the package, and the vibration of the vibrator is hardly leaked to the outside. It has a problem that the effect is limited because it is transmitted to. In addition, since the direction of detection is determined by the direction of the element, there is a problem that restrictions are imposed due to the arrangement of the angular velocity detection elements.

  The conventional configuration of Patent Document 3 has a problem that a low-order mode frequency is lowered because the heavy support portion on which the vibrator is placed is held only by the silicone rubber member. Although a low mode frequency is used to reduce vibration leakage to the outside, fixing with silicone rubber makes it difficult to ensure the stability of the assembly dimensions such as height, and this imposes a burden on manufacturing management. In addition, a volume change is likely to occur with respect to a change in ambient temperature, and a characteristic change of the angular velocity sensor is likely to occur. Further, since silicone rubber has low rigidity, there is a concern that externally applied vibration may adversely affect the vibrator. Similarly to Patent Document 1, when the temperature applied to the sensor changes, the rigidity of the silicone rubber changes. Therefore, even in this structure, it cannot be avoided that the characteristics change due to the change of the natural frequency. Furthermore, in the first place, it is difficult for resins such as silicone rubber to satisfy high quality requirements for automobiles.

  The present invention has been made in consideration of the above points, and an object of the present invention is to provide an angular velocity sensor that can prevent the vibration of the angular velocity detection element from leaking to the outside.

  The present invention includes an angular velocity detecting element having a base, a pair of two driving arms and a pair of two detecting arms, and a package for holding the angular velocity detecting element via a fixed frame, The pair of drive arms and the pair of detection arms of the angular velocity detection element extend in the longitudinal direction opposite to each other with the base as a base point, and the angular velocity sensor The detection element is fixed at the base and a base of the fixed frame, is parallel to a longitudinal direction in which the pair of drive arms and the pair of detection arms extend, and the angular velocity detection element is axisymmetric. A center axis of rotation which is an axis extending in a longitudinal direction, and the fixed frame is provided with a balancer in the vicinity of a base portion of the angular velocity detecting element in line symmetry with respect to the center axis of rotation; Along the axis An angular velocity sensor characterized by comprising a torsion spring unit.

  With such a configuration, vibration generated in the angular velocity detection element can be suppressed by the balancer having inertia, and furthermore, the torsion spring portion holds the angular velocity detection element and the balancer while damping the angular velocity. It is possible to prevent the vibration of the detection element from leaking to the outside.

  Further, by optimizing the materials and the dimensions of the balancer and the torsion spring portion, it is possible to prevent the vibration generated in the angular velocity detecting element from leaking to the outside.

  According to the present invention, it is possible to provide an angular velocity sensor that can prevent the vibration of the angular velocity detection element from leaking to the outside.

It is a disassembled perspective view which shows the angular velocity sensor of embodiment. It is a disassembled perspective view which shows the angular velocity detection element structure of embodiment. It is a disassembled perspective view which shows the angular velocity detection element structure of embodiment. It is a figure which shows the simulation value of the fixed part reaction force of a comparison structure. It is a figure which shows the simulation value of the fixed part reaction force of embodiment. It is a figure which shows the density of the material of embodiment, and the relationship between fixed part maximum reaction force. It is a partial section perspective view showing the angular velocity sensor of the modification of an embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

(Embodiment)
Embodiments will be described with reference to the drawings. In these drawings, electrodes and wiring portions are omitted for easy understanding of the shape. Of course, these are necessary for actual sensors.

  FIG. 1 is an exploded perspective view of a piezoelectric vibration type angular velocity sensor 1 of the present embodiment. In FIG. 1, the angular velocity sensor 1 holds an angular velocity detection element 3 and an angular velocity detection element 3 via a fixed frame 4. A package 5 is provided. The package 5 corresponds to a case in which the angular velocity detection element 3 and the fixed frame 4 are mounted, and includes means for connecting the angular velocity detection element 3 and an external electric circuit. Although not shown, the angular velocity sensor 1 is one component that constitutes a system for detecting the angular velocity. In many cases, the angular velocity sensor 1 is used by being mounted on a circuit board together with surrounding circuit components. In the embodiment, this circuit board is referred to as an external circuit board.

  Examples of the shape of the angular velocity detecting element 3 that detects the angular velocity by the Coriolis force include a tuning fork type having a substantially U shape and a substantially H shape. In particular, the H-shaped angular velocity detecting element having an H shape is a shape suitable for realizing high sensitivity and low noise.

  In FIG. 1, the angular velocity detection element 3 is connected to the fixed frame 4 via a pedestal 6. The size of the pedestal 6 does not hinder the movement of the vibrating arm of the angular velocity detecting element 3, and the thickness is also optimal so that it does not interfere with the package 5 and the fixed frame 4 when the vibrating arm vibrates. It has become.

  FIG. 2 is an exploded perspective view showing details of the angular velocity detecting element structure 2 of the present embodiment, and FIG. 3 is a perspective view showing details of the angular velocity detecting element structure 2 of the present embodiment. The angular velocity detection element structure 2 is a structure in which the angular velocity detection element 3 is connected to the fixed frame 4 via the pedestal 6.

  In FIG. 2, the angular velocity detection element 3 includes a base portion 7 located at the center, a pair of driving arms 8 extending in a predetermined direction across the base portion 7, and a pair of driving arms 8 extending in the opposite direction to the driving arms 8. A detection arm 9 is provided. The angular velocity detecting element 3 composed of the base 7, the driving arm 8, and the detecting arm 9 is made of a common material, for example, Si or quartz, and integrally or by patterning processing (MEMS processing) of a wafer made of general Si or the like. It can be formed in a lump.

  The drive arm 8 and the detection arm 9 are vibration arms, and each arm is provided with a piezoelectric element for enabling vibration. Note that the piezoelectric element is omitted and is not shown, but is made of a piezoelectric material such as PZT. An electric signal is input to and output from the piezoelectric element, and the piezoelectric element can vibrate. As shown in FIG. 1, the holding direction of the angular velocity detection element 3 is selected so that the longitudinal direction of the angular velocity detection element 3 matches the direction of the rotation center axis 10 shown in FIG. As shown in FIG. 3, the base portion 7 includes a fixed portion 11 connected via the fixed frame 4 and the pedestal 6, and a support portion 12 that supports the drive arm 7 and the detection arm 8. The fixing portion 11 is located at the approximate center of the base portion 7. The center axis 10 of rotation is the center of rotation of the angular velocity detection element 3 and the fixed frame 4, that is, the angular velocity detection element structure 2, and is in the longitudinal direction in which the pair of driving arms 8 and the pair of detection arms 9 extend. It is an axis that is parallel and substantially at the center of the torsion spring portion 13 in the thickness direction, and that makes the angular velocity detection element 3 line-symmetric with respect to the longitudinal direction.

  The angular velocity sensor 1 operates in a drive vibration mode in which the drive arm 8 is initially excited and a detection vibration mode in which the detection arm 9 detects the angular velocity orthogonal to the direction of the drive vibration. When the drive arm 8 is driven at a frequency close to the resonance frequency of the detection vibration mode selected for detecting the Coriolis force, both the drive arm 8 and the detection arm 9 are likely to swing with respect to the drive vibration. It has been confirmed from experience that a detection signal can be obtained and the sensitivity of the angular velocity sensor itself is improved. That is, it can be considered that the sensitivity of the sensor is maximized when the resonance frequency of the detected vibration and the resonance frequency of the drive vibration are brought close to each other and the drive arm 8 is driven at a frequency close thereto.

  However, when the angular velocity detection element 3 is directly fixed to the package 5 as in the conventional piezoelectric vibration type angular velocity sensor, the detection is performed by the asymmetry of the angular velocity detection element 3 even though the angular velocity is not applied. The arm 9 may start to vibrate in a direction orthogonal to the drive arm 8. This phenomenon is called leakage vibration. Leakage vibration is also caused by the detection vibration mode, and is vibration in the out-of-plane direction orthogonal to the drive vibration mode.

  When leakage vibration occurs due to the asymmetry of the frequency adjacent to the angular velocity detection element 3 or the like, the angular velocity detection element 3 generates a force to rotate about the longitudinal axis 10. The moment of the angular velocity detection element 3 is transmitted as a reaction force to the surface of the package 5 where the angular velocity detection element is mounted, and this force vibrates the external circuit board. If this leakage vibration leaks from the angular velocity detecting element 3 to the outside through the package 5, the external circuit board (not shown) on which the angular velocity sensor 1 is mounted resonates due to the leakage vibration, and the sensor erroneously generates unnecessary vibration as an offset output. This causes a defect to be detected, leading to deterioration of characteristics as a sensor.

  In FIG. 2, the vibrating arm of the angular velocity detecting element 3 includes a driving arm 8 and a detecting arm 9, which extends in parallel with the longitudinal direction of the fixed frame 4, and has a pair of driving arms 8 with a base 7 as a base point. It is preferable that the pair of detection arms 9 extend in opposite directions to each other, and at least one torsion spring portion 13 is provided on each of the drive arm 8 side and the detection arm 9 side. By doing in this way, the angular velocity sensor 1 which can maintain very high rigidity with respect to the vibration and impact which translate in the thickness direction and prevents the vibration from leaking to the outside can be obtained.

  In FIG. 2, a fixed frame 4 is a frame for fixing the angular velocity detecting element 3 to the package 5, and a torsion spring portion 13 and a balancer 14 for preventing the vibration of the angular velocity detecting element 3 from leaking to the outside. It has a vibration resistant structure. Inside the fixed frame 4, there is a pair of weights called a balancer 14 in the width direction, that is, the X-axis direction, and a torsion spring portion 13 that extends in a straight line in the directions of the drive arm 8 and the detection arm 9. It has a structure to support.

  In FIG. 2, the torsion spring 13 is preferably made of a metal material such as stainless steel. For example, the torsion spring portion 13 can have a rectangular column shape with a rectangular cross section. In particular, the prism shape has a thickness direction, i.e., Z-axis direction vibration rigidity and width direction, i.e., X-axis direction vibration rigidity. This is preferable because it can be clearly divided. As an example, from the point of impact resistance, if you want to have a certain degree of freedom in the width direction while maintaining rigidity in the thickness direction, you can configure a larger size in the thickness direction and a smaller size in the width direction. .

  In FIG. 2, the balancer 14 is preferably made of the same material as that of the torsion spring portion 13 and is made of a material having a high density. The balancer 14 can use, for example, a shape that protrudes in the width direction, that is, the X-axis direction in the vicinity of the base portion 7 of the angular velocity detection element 3, and in particular, a shape that protrudes in the longitudinal direction, that is, the Y-axis direction simultaneously with the width direction. If so, it is desirable because it functions as a larger weight in the thickness direction, that is, in the Z-axis direction.

  Moreover, it is preferable that the balancer 14 and the torsion spring part 13 are comprised with metal materials, such as a stainless alloy and an iron nickel cobalt alloy. By using a metal material, high rigidity can be maintained against vibration that translates in the thickness direction, and thus an angular velocity sensor that prevents leakage of vibration to the outside can be obtained.

  The larger the balancer 14 is in the width direction, that is, in the X-axis direction, the higher the inertia and the greater the effect. On the other hand, if the size in the width direction is small, the inertia is also small and a sufficient effect cannot be obtained. However, weight is important for the function of the balancer 14, and the degree of the effect obtained varies depending on the thickness and density. The ideal shape for obtaining a greater effect is to have a very large shape in the width direction, but the extreme imbalance of the aspect ratio also causes an increase in the size of the package 5 that houses the angular velocity detection element 3. Cost up. By extending the shape in the longitudinal direction, that is, in the Y-axis direction, the weight of the balancer 14 can be increased without unnecessarily increasing the size of the package 5. Moreover, since the effect of the torsion spring portion 13 is further increased by increasing the rotational moment of the balancer 14, it is possible to further prevent the vibration of the angular velocity detecting element 3 from leaking to the outside.

  In the present embodiment, the angular velocity detection element 3 has a size of about 5 [mm] in the longitudinal direction and about 1 [mm] in the width direction. The size of the fixed frame 4 is about 6 [mm] in the longitudinal direction and about 4 [mm] in the width direction. The balancer 14 has a size of about 2 [mm] in the longitudinal direction and about 1 [mm] in the width direction, which are arranged in a pair in the width direction. The torsion spring portion 13 has a width of about 0.3 [mm] and a thickness of about 0.3 [mm].

  4 and 5 show graphs of effects according to this embodiment. 4 and 5 are simulation results of the reaction force of the fixed portion 11 connected to the pedestal 6 located substantially at the center of the base portion 7 of the angular velocity detecting element 3 when the driving arm 8 is vibrated at the driving frequency. is there. The vertical axis represents the reaction force value of the fixed portion 11. The reaction force of the fixed portion 11 indicates a reaction force that occurs at a point where displacement or a constraint of displacement 0 is forcibly defined. The smaller this value, the more the angular velocity detection element 3 swings the package 5. Therefore, vibration leaking to the outside is also reduced. The horizontal axis indicates the phase, and the unit is time [second].

4 is a result of plotting the reaction force value of the comparative structure without the fixed frame 4, and the graph of FIG. 5 is a reaction force with the fixed frame 4 having the vibration-resistant structure of the embodiment. It is the result of plotting the values. The plotted line is the result of observing the point having the largest amplitude in the positive and negative directions from the plurality of observed points. A behavior that starts with a positive reaction force from a point of phase 0 is represented by a circle, and a behavior that starts with a negative reaction force from a point of phase 0 is represented by a square. From FIG. 4, a reaction force having a maximum reaction force value of 0.6 [mN] was detected in the comparative structure, that is, the structure without the fixed frame 4. On the other hand, from FIG. 5, in the configuration including the fixed frame 4 having the vibration-resistant structure of the embodiment, the reaction force can be reduced to a maximum of 0.2 [mN], which is about 1/3, as compared with the comparative structure. That is, it shows that the vibration leakage to the outside of the angular velocity detecting element 3 can be greatly reduced and improved. The numerical values on the vertical axis in FIGS. 4 and 5 are values multiplied by 10 ⁻⁴ .

  It is also preferable that the torsion spring portions 13 have different lengths on the drive arm 8 side and the detection arm 9 side. The angular velocity detection element 3 may be designed so that the lengths of the drive arm 8 and the detection arm 9 are different in order to obtain higher detection sensitivity. In many cases, the length of the drive arm 8 having the means for forcibly vibrating is short, and the length of the detection arm 9 in which the vibration is generated by the vibration of the drive arm 8 is long. As a result, the center of gravity of the angular velocity detection element 3 is located slightly on the detection arm 9 side, and the detection vibration that vibrates in the thickness direction of the angular velocity detection element 3 is unbalanced with different amplitudes on the drive arm 8 side and the detection arm 9 side. Vibration. By making the length of the torsion spring 13 different between the drive arm 8 side and the detection arm 9 side, this imbalance can be corrected, and vibration leaking from the angular velocity detection element 3 to the outside can be reduced.

FIG. 6 shows the result of simulation analysis of the relationship between the density of the material used for the balancer 14 and the torsion spring portion 13 and the maximum reaction force generated in the fixed portion 11 in the embodiment. When the density of the balancer 14 and the torsion spring 13 is increased to 4000 [kg / m ³ ] or more, the maximum reaction force of the fixed portion decreases rapidly. This is because the mass of the balancer 14 and the torsion spring portion 13 increases due to the increase in density, and the angular velocity detection element 3 exceeds the force that shakes the package 5. The material of the balancer 14 and the torsion spring portion 13 preferably has a density of 4000 [kg / m ³ ] or more. In addition, the numerical value of the vertical axis | shaft of FIG. 6 becomes a value which multiplies ^10-4.

  With the configuration of the embodiment, vibration generated in the angular velocity detection element can be suppressed by a balancer having inertia, and further, the torsion spring portion holds the angular velocity detection element and the balancer while suppressing vibrations. It is possible to prevent the vibration of the angular velocity detecting element from leaking to the outside.

  It is also preferable that the length of the torsion spring portion on the drive arm side and the torsion spring portion on the detection arm side in the extending direction is longer on the detection arm side than on the drive arm side. By doing so, it is possible to suppress vibration generated mainly by imbalance between the drive arm and the detection arm among vibrations generated in the angular velocity detection element, and to prevent the vibration of the angular velocity detection element from leaking to the outside.

(Modification)
FIG. 7 shows a partial cross-sectional perspective view centering on the base portion 7 of the angular velocity detection element 3 when cut along the line AA in FIG. In the embodiment, the package 5 and the fixed frame 4 are fixed, but in a modified example, the protrusion 15 protruding from the package 5 has a structure that supports the vicinity of the center of gravity of the angular velocity detection element 3. The reason why the vibration of the angular velocity detection element 3 leaks to the outside is that the vibration in the thickness direction, that is, the Z-axis direction, which is generated due to the vibration imbalance between the drive arm 8 and the detection arm 9 is transmitted. As in the modification of the embodiment shown in FIG. 7, by supporting the fixed frame 4 having the vibration-resistant structure with the protrusions 15, not only can the vibration-resistant structure be prevented from vibrating in the thickness direction, Since the left and right operations are facilitated around the apex, the effect of the torsion spring portion 13 can be further enhanced. In other words, with respect to the vibration that translates in the thickness direction, the vibration in the left-right direction can have a degree of freedom of rotation while holding the angular velocity detecting element with high rigidity and high vibration resistance.

  In the modification of FIG. 7, the size of the protrusion 15 is not particularly required as long as the fixed frame is supported at the top. In this example, the shape is hemispherical, the radius is about 0.2 [mm], and the height is 30 [μm]. The protrusions can be formed using a technique such as printing.

  The balancer 14 is integrated with the fixed frame 4 provided with the torsion spring 13, and the angular velocity sensor 1 includes a package 5 for holding the angular velocity detection element 3 via the fixed frame 4. It is preferable that the package 5 and the fixed frame 4 are supported by a protrusion 15 protruding from the fixed frame 4 in the vicinity of the center of gravity of the detection element 3 or the position of the center of gravity of both members of the angular velocity detection element 3 and the fixed frame 4. By doing so, it is not necessary to change the shape on the package 5 side, and since the conventional package can be used, it is possible to obtain the angular velocity sensor 1 having high vibration resistance while suppressing an increase in cost.

  The angular velocity sensor according to the present invention can be used for applications such as automobiles, car navigation, camera shake prevention cameras, and the like that detect angular velocities due to rotation of a substance.

DESCRIPTION OF SYMBOLS 1 Angular velocity sensor 2 Angular velocity detection element structure 3 Angular velocity detection element 4 Fixed frame 5 Package 6 Base 7 Base 8 Drive arm 9 Detection arm 10 Rotating shaft 11 Fixing part 12 Supporting part 13 Torsion spring part 14 Balancer 15 Protrusion part

Claims (7)

Angular velocity sensor having a base, an angular velocity detecting element having two pairs of driving arms and a pair of two detecting arms, and a package for holding the angular velocity detecting element via a fixed frame Because
The pair of drive arms and the pair of detection arms of the angular velocity detection element extend in the longitudinal direction in opposite directions from each other with the base as a base point.
The angular velocity detection element is fixed to the base and a base of the fixed frame, is parallel to a longitudinal direction in which the pair of driving arms and the pair of detection arms extend, and the angular velocity detection element is axisymmetric. Having a central axis of rotation that is an axis extending in the longitudinal direction,
The fixed frame is provided with a balancer in the vicinity of the base of the angular velocity detecting element in line symmetry with respect to the central axis of rotation, and further includes a torsion spring portion along the central axis of rotation. A featured angular velocity sensor. 2. The angular velocity sensor according to claim 1, wherein the balancer and the torsion spring portion are made of a material having a density of 4000 [kg / m ³ ] or more such as a stainless alloy or an iron nickel cobalt alloy.   The angular velocity sensor according to claim 1, wherein the balancer has a structure wider than the torsion spring portion.   4. The angular velocity sensor according to claim 1, further comprising at least one torsion spring portion on each of the drive arm side and the detection arm side of the angular velocity detection element. 5.   The longitudinal length of the torsion spring part on the drive arm side and the torsion spring part on the detection arm side is longer on the detection arm side than on the drive arm side, The angular velocity sensor according to claim 4. The angular velocity sensor includes a package for holding the angular velocity detection element via the fixed frame;
In the vicinity of the center of gravity of the angular velocity detecting element, or the position of the center of gravity of both the angular velocity detecting element and the fixed frame,
The angular velocity sensor according to claim 1, wherein the fixed frame is supported by a protrusion protruding from the package. The balancer is integral with the fixed frame having the torsion spring,
The angular velocity sensor includes a package for holding the angular velocity detection element via the fixed frame;
In the vicinity of the center of gravity of the angular velocity detecting element, or the position of the center of gravity of both the angular velocity detecting element and the fixed frame,
The angular velocity sensor according to claim 1, wherein the package and the fixed frame are supported by a protrusion protruding from the fixed frame.

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