JP2011242256A - Vibration gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration gyro which is capable of suppressing mixture of an unnecessary signal in a detection signal even when shear strain acts on a package.SOLUTION: A vibration gyro 50 includes a vibrator 1 and a lid plate 50A. The vibrator 1 includes drive mass parts 13A to 13C, a drive beam, detection mass parts 17A to 17D, and a support beam. The drive mass parts 13A to 13C vibrate by a drive. The drive beam supports the drive mass parts 13A to 13C and flexurally vibrates by force acting from the drive mass parts 13A to 13C. The detection mass parts 17A to 17D are supported by the drive mass parts 13A to 13C in a state of being freely displaced in response to the Coriolis force acting due to vibrations of the drive mass parts 13A to 13C. The support beam supports the drive beam in a position being a node of flexural vibration. The lid plate 50A is parallel with a vibration direction of the drive mass parts 13A to 13C and a displacement direction of the detection mass parts 17A to 17D, and the vibrator is fixed in an area opposite to a center line of the vibrator 1 parallel with the vibration direction.

Description

  The present invention relates to a vibration gyro that drives a vibrator and detects a force acting in a direction orthogonal to the vibration direction.

  A certain type of vibrating gyroscope vibrates the vibrator with the X axis in the Cartesian coordinate system with the main surface normal direction of the support plate as the Z axis as the driving direction, and the vibrating gyroscope rotates around the Z axis. The Coriolis force acting in the orthogonal Y-axis direction is detected from changes in the electrode spacing and interelectrode capacitance between the detection fixing structure and the vibrator. (For example, refer to Patent Documents 1 and 2).

Here, a configuration example of a conventional vibrating gyroscope will be described.
FIG. 1A is a plan view of a conventional vibrating gyroscope 101.

The vibration gyro 101 includes a cover plate (not shown), a support plate 102A, an outer frame portion 102B, an anchor 103, a drive beam 104A, drive mass units 105A to 105C, a detection beam 104B, detection mass units 106A to 106C, and detection electrodes 107A to 107A. 107D, support | pillar part 108A-108D, and the fixing structure part 109 for a drive are provided.
The outer frame portion 102B is joined to a support plate 102A and a lid plate (not shown). The anchor 103, the driving beam 104A, the driving mass units 105A to 105C, the detection beam 104B, and the detection mass units 106A to 106C constitute an integrated vibrator made of a low resistance silicon material (conductive) and are connected to the ground. The detection electrodes 107A to 107D and the support portions 108A to 108D constitute a detection fixed structure portion made of a low resistance silicon material (conductive).

  The driving beam 104A constituting the vibrator is supported by the outer frame portion 102B with two anchors 103 that are connected to the side surface in the X-axis direction with the Y-axis direction as the longitudinal direction. The driving mass portions 105A and 105B are connected between the ends of the two driving beams 104A, and the driving mass portion 105C is connected between the central portions of the two driving beams 104A. The detection mass units 106A to 106C are connected to the drive mass units 105A to 105C via the detection beams 104B in the openings provided in the drive mass units 105A to 105C, respectively.

  The detection electrodes 107A to 107D and the support column portions 108A to 108D constituting the detection fixing structure unit are arranged in the openings provided in the detection mass units 106A to 106C and spaced from the detection mass units 106A to 106C, and the support column units 108A to 108A. The support plate 102A and the lid plate (not shown) are joined by 108D. The detection electrode 107A and the detection electrode 107C are connected on the upper surface of the lid plate, and the detection electrode 107B and the detection electrode 107D are also connected on the upper surface of the lid plate.

  Similarly to the detection fixing structure portion, the driving fixing structure portion 109 is joined to the support plate 102A and a cover plate (not shown) by a support portion, and a driving voltage is applied thereto. As a result, the driving mass portions 105A to 105B constituting the vibrator vibrate in the driving direction along the X axis, and the driving beam 104A is also deformed (flexed vibration) in the same direction. When the vibrating gyroscope 101 rotates around the Z axis in this state, Coriolis force in the direction along the Y axis acts on the detection mass units 106A to 106C, and the detection mass units 106A to 106C are displaced in that direction. Thereby, the electrode interval between the detection mass units 106A to 106C and the detection electrodes 107A to 107D and the capacitance between the electrodes change. At this time, in the detection mass units 106A and 106B and the detection mass unit 106C, the vibrations in the X-axis direction are in opposite phases, and the Coriolis force acts in the opposite direction. Therefore, if the combined capacitance is detected from the detection electrodes 107A and 107C and the combined capacitance is also detected from the detection electrodes 107B and 107D, the angular velocity around the Z axis of the vibration gyro 101 can be detected from the differential capacitance of both.

  Note that when acceleration along the Y-axis is applied to such a vibrating gyroscope 101, the inertial force acting on each of the detection mass units 106A to 106C is in the same direction in all of the detection mass units 106A to 106C. For this reason, in the differential capacitor, changes in the capacitance between the electrodes cancel each other, and the angular velocity around the Z axis can be detected without being affected by the acceleration in the Y axis direction.

FIG. 1B is a plan view of a conventional vibrating gyroscope 201.
The vibration gyro 201 has the same main part configuration as that of the vibration gyro 101 but is different in the support portion of the vibrator. Specifically, the driving beam 204 is connected to two sub-anchors 203, the sub-anchors 203 are connected to both ends of one side surface of the support beam 205 having the longitudinal direction in the Y-axis direction, and the central portion of the other side surface of the support beam 205 Is connected to the outer frame portion 202 </ b> B via the anchor 206.

FIG. 1C is a plan view of a conventional vibrating gyroscope 301.
The vibrating gyro 301 includes a vibrator including four driving mass units and a detection mass unit arranged inside the two inner driving mass units. In the vibration gyro 301, both ends and the center of the drive beam 307 are connected to three sub-anchors 306, and the sub-anchor 306 is connected to one side surface of the support beam 305 having a longitudinal direction in the Y-axis direction. The central portion of the other side surface is connected to the outer frame portion 302B via the anchor 304.

Japanese Patent No. 3589182 Japanese Patent No. 3870895

FIG. 2 is a schematic diagram for explaining a modification example in the case where shear strain is generated in the conventional vibrating gyroscope 301. In the figure, A1, A2 (A1 ′, A2 ′) indicate connection points between the anchor 304 and the outer frame portion 302B, that is, fixed points of the vibrator.
When shear strain is applied to the casing of the vibration gyro 301, the size of one of the rectangles in the diagonal direction is expanded, and the size of the other diagonal direction is reduced. From the rectangle shown in FIG. 2 (A) to the parallel shown in FIG. 2 (B). The housing is deformed into a quadrilateral. By this deformation, the fixed point of the vibrator is rotationally displaced from the fixed points A1 and A2 to the fixed points A1 ′ and A2 ′. At this time, since the vibrator is fixedly supported on the wall surface via the anchor 304, the driving beam 307 tries to maintain a state substantially parallel to the wall surface, and the support direction of the vibrator, which is the normal direction of the wall surface, is the fixed point. It rotates in the direction opposite to the rotational displacement direction. For this reason, an excessive shearing strain acts on the vibrator and deforms greatly. Then, the orthogonality between the driving direction in which the driving mass unit vibrates and the direction in which the detection mass unit vibrates (detection direction) due to the Coriolis force is lost, and an unnecessary signal due to driving is mixed into the detection signal. This problem similarly occurs in the conventional vibration gyro 101 and vibration gyro 201.

  Since the above-mentioned unnecessary signal is 90 ° out of phase with the normal detection signal, it can be almost eliminated by performing synchronous detection of the detection signal. However, if there is an initial phase shift of synchronous detection or a phase change due to temperature, it becomes difficult to completely remove unnecessary signals from the detection signal. Therefore, the output fluctuation and temperature characteristics of the vibration gyro deteriorate due to the shear strain.

  In addition, due to the initial distortion of the casing, unnecessary signals are mixed in the detection signal even when the angular velocity around the Z-axis is not acting. Therefore, the signal amplification factor before synchronous detection cannot be increased, and the sensor sensitivity is set to the design value. For this purpose, it is necessary to increase the signal amplification factor after synchronous detection. The SN ratio of the vibration gyro is better when the signal amplification factor before synchronous detection is larger. If the signal amplification factor after synchronous detection is larger, the SN ratio is lowered.

  Therefore, an object of the present invention is to provide a vibrating gyroscope that can prevent an unnecessary signal from being mixed into a detection signal even if a shear strain acts on the casing.

The vibration gyro according to the present invention includes a vibrator and a support plate. The vibrator includes a drive mass unit, a drive beam, a detection mass unit, and a support beam. The driving mass unit vibrates by driving. The drive beam supports the drive mass unit and bends and vibrates due to the force acting from the drive mass unit. The detection mass unit is supported by the drive mass unit in a state in which the detection mass unit can be displaced with respect to the Coriolis force acting by the vibration of the drive mass unit. The support beam supports the drive beam at a position where it becomes a bending vibration node. The support plate is parallel to the vibration direction of the drive mass unit and the displacement direction of the detection mass unit. In the vibration gyro configured as described above, the vibrator is fixed to the support plate in a region passing through the center of the vibrator and facing a center line parallel to the vibration direction.
In this configuration, when a shear strain acts on the support plate, the fixing point between the support beam and the support plate is rotationally displaced following the rotation of the center line of the vibrator. At that time, since the support beam is fixedly supported with the normal direction of the support plate as the support direction, the support direction does not rotate in the direction opposite to the rotational displacement direction of the fixed point unlike the conventional structure, and The acting shear strain is extremely reduced. Therefore, the vibration gyro having this configuration has high orthogonality between the driving direction and the detection direction even in a state where shear strain is applied to the casing, and can prevent the detection signal from being mixed with an unnecessary signal.

The support beam of the present invention is preferably in the form of a straight beam orthogonal to the center line.
In this configuration, the rigidity of the support beam is high, and the deformation of the drive beam and the displacement of the connecting portion (sub-anchor) can be suppressed by suppressing the deflection of the support beam, so that a high-performance vibration gyro can be configured.

The vibrating gyroscope according to the present invention is preferably a connecting portion (sub-anchor) that bends in a meander line shape to connect the support beam and the driving beam.
In this configuration, the position serving as a vibration node in the drive beam is elastically supported without being restricted, and thereby shear strain acting on the support beam can be released by the connecting portion. Therefore, the shear strain extending to the drive beam and each mass part can be reduced.

The vibration gyro of the present invention includes an outer frame portion that houses the vibrator inside the opening, a lid plate and a bottom plate that closes the opening of the outer frame portion, and has a structure in which an outer main surface of the bottom plate is a mounting surface. It is preferable that only the lid plate be joined to the vibrator to form a support plate.
In this configuration, since the shear strain acting on the bottom plate fixed to the other member acts on the vibrator via the outer frame portion and the cover plate, the shear strain acting on the vibrator can be reduced.

  According to the present invention, the vibrator is fixed to the support plate in a region facing the center line passing through the center of the vibrator and parallel to the vibration direction. Therefore, when shear strain acts on the support plate, Thus, the supporting direction does not rotate in the direction opposite to the rotational displacement direction of the fixed point, and the shear strain acting on the vibrator is extremely reduced. Therefore, the vibration gyro having this configuration has high orthogonality between the driving direction and the detection direction even in a state where shear strain is applied to the casing, and can prevent the detection signal from being mixed with an unnecessary signal.

It is a figure explaining the structure of the conventional vibration gyroscope. It is a figure explaining the modification by the shear distortion of the conventional vibration gyroscope. It is a figure explaining the structure of the vibration gyroscope which concerns on the 1st Embodiment of this invention. It is a figure explaining operation | movement of the vibration gyro shown in FIG. FIG. 4 is a partially enlarged view of the vibration gyro shown in FIG. 3. It is a figure explaining the circuit structure of the drive detection circuit connected to the vibration gyro shown in FIG. It is a figure explaining the influence by the shear distortion of the vibration gyro shown in FIG. It is a figure explaining the structure of the vibration gyroscope which concerns on the 2nd Embodiment of this invention. It is a figure explaining operation | movement of the vibration gyro shown in FIG. It is a figure explaining the influence by the shear distortion of the vibration gyro shown in FIG. It is a figure which compares and demonstrates an Example and a prior art example.

  In the following description of the vibration gyro, the rotation detection axis of the vibration gyro when no shear strain is applied is the Z axis of the orthogonal coordinate system, the drive direction is the X axis direction of the orthogonal coordinate system, and the direction of action of the Coriolis force is the orthogonal coordinate. This is the Y-axis direction of the system.

  First, the vibration gyro 50 according to the first embodiment of the present invention will be described. 3A is a plan view showing the configuration of the vibrating gyroscope 50, and FIG. 3B is a cross-sectional view along the X axis passing through the center of the vibrator in a state where the vibrating gyroscope 50 is mounted on the mounting substrate 150. .

  The vibration gyro 50 has a configuration in which a lid plate 50A (support plate), a low-resistance silicon plate 50B, and a bottom plate 50C are sequentially stacked along the Z-axis in a step view. The low-resistance silicon plate 50B is divided into the following configuration, vibrator 1, detection fixing structure portions 2A and 2B, driving fixing structure portions 3A and 3B, monitor fixing structure portions 4A and 4B, and an outer frame portion. 5 is provided. The cover plate 50A, the outer frame portion 5, and the bottom plate 50C constitute a housing having an internal space. This casing is bonded to the mounting substrate 150 on the outer main surface of the bottom plate 50C, and external connection terminals (not shown) formed on the outer main surface of the lid plate 50A are wire-bonded to mounting electrodes (not shown) on the mounting substrate 150. To do.

  The schematic structure of the vibrating gyroscope 50 will be described. The vibrator 1 is fixed to the cover plate 50A at positions (fixed points A1, A2) on the X axis passing through the center of the vibrator 1 on the XY plane. Further, the drive mass units 13A to 13C are provided as regions that are displaceable in the X-axis direction, and the detection mass units 17A to 17D are provided as regions that are displaceable in the Y-axis direction.

The detection fixing structures 2A and 2B are provided to detect the Coriolis force acting on the vibrator 1 by detecting the interelectrode capacitance between the detection mass parts 17A to 17D. It arrange | positions inside opening and is being fixed to the cover board 50A and the baseplate 50C so that the whole may not deform | transform.
The driving fixing structure portions 3A and 3B are arranged on both outer sides of the Y axis across the vibrator 1 and are fixed to the lid plate 50A and the bottom plate 50C so as not to be deformed as a whole. By applying a driving voltage to the driving fixing structure portions 3A and 3B, the electrostatic force between the driving fixing structure portions 3A and 3B and the driving mass portions 13A and 13B varies, and vibration in the X-axis direction occurs. .

  The monitor fixing structures 4A and 4B are arranged on both outer sides of the X-axis sandwiching the vibrator 1, and are fixed to the cover plate 50A and the bottom plate 50C so as not to be deformed as a whole. The monitor fixing structure portions 4A and 4B detect the interelectrode capacitance between the driving mass portion 13C and adjust the driving voltage applied to the driving fixing structure portions 3A and 3B, thereby appropriately adjusting the vibration of the vibrator 1. It is provided to make things better.

  FIG. 4A is a diagram for explaining deformation due to driving of the vibrator 1. The drive mass units 13A to 13C vibrate in the X-axis direction when the electrostatic force varies between the drive mass units 13A and 13B and the above-described drive fixing structure units 3A and 3B (not shown). The driving directions of the driving mass units 13A and 13B and the driving mass unit 13C are reversed.

  FIG. 4B is a diagram for explaining deformation of the vibrator 1 due to Coriolis force. When an angular velocity around the Z axis acts on the vibrator 1, a Coriolis force acts on the detection mass units 17A to 17D. Since the driving directions of the driving mass units 13A and 13B and the driving mass unit 13C are opposite to each other, the Coriolis force also acts in the opposite direction. , 17D are displaced in the positive direction of the Y-axis.

Returning to FIG. 3 again, the detailed structure of the vibrating gyroscope 50 will be described.
The vibrator 1 has the following structure integrally formed, support anchors (support beams) 10A to 10D, sub-anchors 11A to 11D, drive beams 12A and 12B, drive mass portions 13A to 13C, and drive comb teeth portions 14A and 14B. (Partially not shown), detection beams 15A to 15D, 16A to 16D, detection mass parts 17A to 17D, detection comb teeth 18A to 18D (partially not shown), and monitor comb teeth 19A and 19B (partially not shown) As shown).

The driving comb portions 14A and 14B are attached to the driving mass portions 13A and 13B, respectively. FIG. 5A is an enlarged plan view in the vicinity of the driving comb portion 14A. The drive comb tooth portion 14B has the same configuration as the drive comb tooth portion 14A.
The driving comb portion 14A includes a comb electrode protruding in a comb shape along the X axis from one side surface of a linear portion protruding along the Y axis from the side surface of the driving mass portion 13A. The comb-tooth electrode of the drive comb-tooth portion 14A faces the comb-tooth electrode 33 included in the drive fixing structure portion 3A with a minute gap. The driving fixing structure 3A includes a columnar column 31 fixed to the cover plate 50A and the bottom plate 50C, a linear portion 32 connected to the column 31, and the linear portion 32 along the X axis. And a comb electrode 33 protruding in a comb shape. The driving fixing structure 3A is electrically connected to the external connection terminal by a via electrode provided on the cover plate 50A. With such a configuration, when a driving voltage (bias voltage and alternating voltage) is applied between the driving comb tooth portion 14A and the driving fixing structure portion 3A, the driving comb tooth portion 14A and the driving fixing structure portion 3A The driving mass unit 13A vibrates along the X axis due to the fluctuation of the electrostatic force during the period.

  Returning again to FIG. The drive mass units 13A and 13B are arranged along the Y axis so as to sandwich the drive mass unit 13C. The driving mass portions 13A and 13B are substantially U-shaped with the Y-axis inner side opened in a plan view, and the linear portions along the X-axis constituting the bottom surface of the opening project outward from both sides of the X-axis. Are connected to the Y-axis ends of the drive beams 12A and 12B. The driving mass portion 13C is substantially H-shaped with both outer sides of the Y-axis opened in plan view, and is connected to the Y-axis central portion of the driving beams 12A and 12B at both ends of the linear portion along the X-axis of the Y-axis central portion. is doing.

  The driving beams 12A and 12B are arranged on both outer sides of the X axis with the driving mass portions 13A to 13C interposed therebetween. Each of the driving beams 12A and 12B has a substantially linear shape that is long in the Y-axis direction when seen in a plan view, and is thus configured to be deformable (flexible vibration) in the X-axis direction. The drive beams 12A and 12B are connected to the sub-anchors 11A to 11D at a position that is approximately ¼ length with respect to the entire length in the Y-axis direction and a position that is approximately ¾ length. The sub-anchors 11A to 11D have a substantially meander shape meandering with respect to the X axis, and one end is connected to the side surfaces of the drive beams 12A and 12B and the other end is connected to the side surfaces of the support anchors 10A to 10D. The support anchors 10A to 10D have a substantially linear shape that is long in the Y-axis direction, and end portions on the inner side of the Y-axis are fixed to the cover plate 50A at fixing points A1 and A2. Since the support anchors 10A to 10D have a substantially linear shape elongated in the Y-axis direction, the support anchors 10A to 10D have high rigidity and can be suppressed from being displaced by vibrations transmitted from the sub-anchors 11A to 11D.

  With the above-described configuration, the positions connected to the sub-anchors 11A to 11D in the driving beams 12A and 12B are the bending vibration nodes (node points) when the driving beams 12A and 12B are deformed (flexing vibration) in the X-axis direction. Become. And the position which supports drive mass part 13A-13C becomes the antinode (antinode point) of a bending vibration, or its vicinity. Accordingly, the drive mass units 13A and 13B vibrate in the same phase in the X-axis direction, and the drive mass unit 13C vibrates in the opposite phase to the drive mass units 13A and 13B in the X-axis direction.

  The detection beams 15A to 15D have a shape in which two linear portions that are long along the X axis in a plan view are parallel and connected at the central portion, and both ends of one linear portion are connected to the driving mass portion 13A. To 13C, and both ends of the other linear part are connected to the detection mass parts 17A to 17D. The detection beams 15C and 15D are connected to the bottom surface of the H-shaped opening of the drive mass unit 13C. The detection beams 16A to 16D are configured in a substantially meander shape meandering with respect to the Y axis in plan view. The detection beams 15A and 15B are connected to the U-shaped opening bottoms of the driving mass portions 13A and 13B. The detection beams 16A and 16B are connected to the U-shaped ends of the drive mass units 13A and 13B. The detection beams 16C and 16D are connected to the H-shaped end of the drive mass unit 13C.

  The detection mass portions 17A and 17C are substantially U-shaped in plan view, and are arranged in the openings of the drive mass portions 13A and 13C so that the respective U-shaped openings face each other, and the detection beams 15A , 15C, 16A, 16C. The detection mass portions 17B and 17D are also substantially U-shaped in plan view, and are arranged in the openings of the drive mass portions 13B and 13C so that the respective U-shaped openings face each other. It is connected to the beams 15B, 15D, 16B and 16D. As described above, since the detection beams 15A to 15D and 16A to 16D each have a meander shape meandering with respect to the Y axis, the detection mass portions 17A to 17D are freely displaceable in the Y axis direction. Is interlocked with the drive mass units 13A to 13C.

  The detection comb teeth portions 18A and 18C are attached in the openings facing the detection mass portions 17A and 17C, and the detection comb teeth portions 18B and 18D are attached in the openings facing the detection mass portions 17B and 17D. FIG. 5B is an enlarged plan view of the vicinity of the detection comb portion 18A. The detection comb teeth 18B to 18D have the same configuration as the detection comb teeth 18A.

  The detection comb portion 18A includes a comb electrode protruding in a comb shape along the X axis in the opening of the detection mass portion 17A. The comb-tooth electrode of the detection comb-tooth portion 18A faces the comb-tooth electrode 23 provided in the detection fixing structure portion 2A with a minute interval. The detection fixing structure 2A includes a support column 21 fixedly supported by the cover plate 50A and the bottom plate 50C, a linear portion 22 connected to the support column 21, and a comb from the linear portion 22 along the X axis. It is the structure provided with the comb-tooth electrode 23 (detection electrode) which protrudes in a tooth shape. In such a configuration, when the detection mass unit 17A is displaced in the Y-axis direction, the interelectrode capacitance between the detection comb portion 18A and the detection fixing structure portion 2A varies.

  Returning again to FIG. The monitor comb teeth portions 19A and 19B are arranged on both outer sides of the X axis with the drive beams 12A and 12B and the drive mass portion 13C interposed therebetween, and are connected to the Y axis central portions of the drive beams 12A and 12B, respectively. FIG. 5C is an enlarged plan view of the vicinity of the monitor comb portion 19A. The monitor comb tooth portion 19B has the same configuration as the monitor comb tooth portion 19A.

  The monitor comb-tooth portion 19A includes a comb-tooth electrode that protrudes along the X-axis from the side surface of a linear portion that extends along the Y-axis and is folded back. The comb-shaped electrode of the monitor comb-tooth portion 19A faces the comb-tooth electrode 43 provided in the monitor fixing structure portion 4A with a minute interval. The monitor fixing structure 4A includes a column 41 (see FIG. 3) fixed and supported by the cover plate 50A and the bottom plate 50C, a linear portion 42 connected to the column 41, and the linear portions 42 to X. It is the structure provided with the comb-tooth electrode 43 which protrudes in a comb-tooth shape along an axis | shaft. With such a configuration, when the drive mass unit 13C is displaced in the X-axis direction, the interelectrode capacitance between the monitor comb portion 19A and the monitor fixed structure portion 4A varies.

  FIG. 6 is a circuit diagram of a drive detection circuit connected to the vibration gyro 50. Here, an example in which the drive detection circuit is configured as a custom IC 151 is shown. The custom IC 151 is preferably mounted on the mounting substrate 150 shown in FIG. 3B, molded integrally with the vibration gyro 50, and configured as an integrated chip element.

The custom IC 151 includes a CV conversion circuit 152, a differential amplifier 153, a synchronous detection circuit 154, a DC amplifier / low-pass filter circuit 155, a digital trimming circuit 156, an amplifier 158, an auto gain control circuit 159, and a phase shifter / sine wave generation A circuit 160 is provided.
The CV conversion circuit 152 is connected to each of the detection fixing structure portions 2A and 2B of the vibration gyro 50 and the monitor fixing structure portions 4A and 4B (or at least one of the monitor fixing structure portions 4A and 4B). A voltage signal corresponding to the interelectrode capacitance is output. The differential amplifier 153 outputs a differential signal of two voltage signals input from the CV conversion circuit 152. By using the differential signal, it is possible to detect only the angular velocity around the Z-axis by canceling the capacitance change when the acceleration in the Y-axis direction acts on the vibration gyro 50. The synchronous detection circuit 154 detects from the differential signal at a timing synchronized with the sine wave generated by the phase shifter / sine wave generation circuit 160. The phase of the X-axis vibration caused by driving and the Y-axis vibration caused by Coriolis force is 90 ° different, so synchronous detection detects the vibration in the Y-axis direction without the influence of vibration in the X-axis direction. It becomes possible to do. The DC amplifier / low-pass filter circuit 155 amplifies the detection signal output from the synchronous detection circuit 154 and cuts a noise component. The digital trimming circuit 156 calibrates the characteristic variation of the vibration gyro 50 in the detection signal and outputs the detection signal. The amplifier 158 amplifies the voltage signal input from the CV conversion circuit 152 (signals from the monitor fixed structures 4A and 4B). The auto gain control circuit 159 and the phase shifter / sine wave generation circuit 160 adjust the phase and amplitude of the drive voltage so that the vibration of the vibration gyro 50 is appropriately maintained, and the fixed structure portion 3A for driving the vibration gyro 50, Output to 3B.
By such a drive detection circuit 151, the vibration gyro 50 vibrates in the driving direction, and an angular velocity around the Z-axis acts on the vibration gyro 50 in the vibration state, whereby a detection signal corresponding to the angular velocity is obtained.

Next, the influence of shear strain in the vibration gyro 50 will be described.
FIG. 7A is a plan view of the vibrating gyroscope 50 showing a cross section of the cover plate 50A. The cover plate 50A has a configuration in which the inner main surface is partially etched away, and includes a frame-shaped part 50A1, a cylindrical part 50A2, and a rectangular part 50A3 that protrude toward the vibrator side. The frame-shaped part 50A1 is a part for fixing the outer frame part 5 and the column parts 31, 41 of the low-resistance silicon plate 50B described above. The cylindrical part 50A2 is a part for fixing the column part 21. The rectangular part 50A3 is a part for fixing one end of the support anchors 10A to 10D. In the present embodiment, the rectangular portion 50A3 is disposed in a region facing the X axis passing through the center of the vibrator 1, and the vibrator 1 is fixedly supported with the position as a fixed point.

  FIG. 7B is a view for explaining a modification of the vibrating gyroscope 50 due to shear strain. When shear strain acts on the casing of the vibration gyro 50, the fixed points A1 and A2 are rotationally displaced in the XY plane with the center of the vibrator 1 as the rotation center. At that time, the vibrator 1 is supported by the above-described rectangular portion 50A3, and the supporting direction is the normal direction of the cover plate 50A. Therefore, the shear strain acting on the vibrator 1 is extremely reduced. Rotate in the same direction as the rotational displacement direction of the fixed point while maintaining.

Since the above-mentioned sub-anchors 11A to 11D are formed in a meander shape, the stress due to the displacement of the support anchors 10A to 10D is released by the deformation of the sub-anchors 11A to 11D. It can prevent more reliably that shear strain is transmitted to 12A, 12B.
Therefore, the vibrating gyroscope 50 according to the present embodiment can maintain the shape of the vibrator 1 even when shearing strain is applied, and can maintain the orthogonality between the driving direction and the detection direction and mix unnecessary signals into the detection signal. Can be suppressed.

  In this embodiment, the example in which both the monitor fixing structures 4A and 4B are used for vibration monitoring is shown. However, only one of them is used for vibration monitoring, and the other has the same potential as the vibrator 1. Then, it may be used so as to be connected to the ground electrode via the support column. In this case, by connecting the vibrator 1 to the ground electrode via a fixed structure portion having the same potential as that of the vibrator, it is not necessary to separately provide a via electrode, and the reduction of the support plate area can be promoted. Even if there is only one fixed structure used for the vibration monitor, it is preferable to dare to form the other fixed structure that is not used for the vibration monitor in order to maintain the symmetry of the vibration gyro 50. .

  Next, a vibrating gyroscope 100 according to a second embodiment of the present invention will be described. FIG. 8 is a plan view showing the configuration of the vibrating gyroscope 100.

  The vibrating gyroscope 100 includes a vibrator 51 having a shape different from that of the first embodiment, but the other schematic configuration is the same as that of the first embodiment.

  The vibrator 51 includes support anchors (support beams) 60A to 60F, sub-anchors 61A to 61F, drive beams 62A and 62B, drive mass units 63A to 63D, drive comb teeth portions 64A and 64B (partially not shown), and detection beams. 65, detection mass portions 67A and 67B, detection comb teeth 68A and 68B (partially not shown), and monitor comb teeth 69A and 69B (partly not shown).

The schematic structure of the vibrating gyroscope 100 will be described. The vibrator 51 is fixed to the support plate at positions (fixed points A1, A2, BA, B2) on the X axis passing through the center of the vibrator 51 on the XY plane. . In addition, the drive mass units 63A to 63D are provided as regions that are displaceable in the X-axis direction, and the detection mass units 67A and 67B are provided as regions that are displaceable in the Y-axis direction.
The detection fixing structure 72 is disposed inside the central opening of the vibrator 51 and is fixed to the support plate so that the whole is not deformed. The driving fixing structure 73 is disposed inside the opening on both outer sides of the Y axis of the vibrator 51, and is fixed to the support plate so as not to be deformed as a whole. The monitor fixing structure 74 is disposed on both outer sides of the Y axis with the vibrator 51 interposed therebetween, and is fixed to the support plate so as not to be deformed as a whole.

  The driving comb-tooth portions 64A and 64B are arranged at positions sandwiched between the driving mass portions 63C and 63D and the driving mass portions 63A and 63B, and comb-tooth electrodes (not shown) projecting in a comb-tooth shape along the X axis. ) And opposes the comb-like electrode (not shown) of the driving fixing structure 73 with a minute gap.

  The driving mass units 63A to 63D are arranged along the Y axis so that the driving mass units 63A and 63B disposed near the center are sandwiched by the driving mass units 63C and 63D. The driving mass units 63A and 63D and the driving mass units 63B and 63C vibrate in the opposite phase in the X-axis direction. The driving mass parts 63A and 63B are substantially U-shaped with the Y-axis inner side opened in a plan view, and are arranged so that the respective openings face each other, and both ends of the linear part along the Y-axis constituting the opening side surface. Are connected to the driving beams 62A and 62B via a T-shaped connecting portion. The driving mass portions 63C and 63D have a linear shape with a long X axis direction when seen in a plan view, and are connected to the driving beams 12A and 12B at both ends.

  The drive beams 62A and 62B are disposed on both outer sides of the X axis with the drive mass parts 63A to 63D interposed therebetween. Each of the drive beams 62A and 62B has a substantially linear shape that is long in the Y-axis direction when seen in a plan view, and is configured to be deformable (flexible vibration) in the X-axis direction. The drive beams 62A and 62B are connected to the sub-anchors 61A to 61F at positions that are approximately 1/4, approximately 2/4, and approximately 3/4 of the total length in the Y-axis direction. The sub-anchors 61A to 61F are substantially U-shaped, and one end is connected to the side surfaces of the drive beams 62A and 62B, and the other two ends are connected to the support anchors 60A to 60F. The support anchors 60A to 60D have a substantially linear shape elongated in the Y-axis direction, and are fixed to the support plate at fixing points A1 and A2. The support anchors 60E and 60F have a rectangular shape arranged in the central opening of the vibrator 1, and are fixed to the support plate at fixing points B1 and B2.

  The detection mass portions 67A and 67B are substantially U-shaped in plan view, and are arranged in the openings of the drive mass portions 63A and 63B so that the respective U-shaped openings face each other, and the detection beam 65 Are connected to the driving mass parts 63A and 63B.

  The detection comb-tooth portions 68A and 68B are attached in openings facing the detection mass portions 67A and 67B. The detection comb-tooth portions 68A and 68B are provided with comb-tooth electrodes (not shown) protruding in a comb-tooth shape along the X axis, and are spaced apart from the comb-tooth electrodes (not shown) provided in the detection fixing structure 72. Facing each other.

  The monitor comb-tooth portions 69A and 69B are arranged on both outer sides of the Y-axis across the drive mass portions 63C and 63D, and are provided with comb-tooth electrodes (not shown) protruding in a comb-tooth shape along the X-axis. It opposes the comb-tooth electrode (not shown) with which the fixed structure part 74 is provided at a minute interval.

  FIG. 9 is a diagram for explaining deformation caused by driving the vibrator 51. When the electrostatic force between the driving mass portions 63A to 63D and the above-described driving fixing structure portion 73 varies, the driving mass portions 63A to 63D are displaced in the X-axis direction. In this state, when an angular velocity around the Z axis acts on the vibrator 51, Coriolis force acts on the detection mass units 67A and 67B. Since the driving mass unit 63A and the driving mass unit 63B have opposite driving directions, the Coriolis force acting on the detection mass units 67A and 67B is also in the opposite direction.

  FIG. 10A is a plan view showing a cross section of a support plate 100A provided in the vibrating gyroscope 100. FIG. The support plate 100A has a configuration in which the inner main surface is partially etched away, and includes a frame-like portion 100A1, a cylindrical portion 100A2, and rectangular portions 100A3 and 100A4 that protrude toward the vibrator 51 side. The frame-shaped part 100A1 is a part for fixing the outer frame part of the low-resistance silicon plate. The columnar part 100A2 is a part for fixing the column part of each fixing structure part. The rectangular part 100A3 is a part for fixing one end of the support anchors 60A to 60D. The rectangular part 100A4 is a part for fixing the support anchors 60E and 60F. In the present embodiment, the rectangular portions 100A3 and 100A4 are arranged in a region facing the X axis passing through the center of the transducer 51, and the transducer 51 is fixed in this region.

FIG. 10B is a diagram for explaining the influence of shear strain in the vibrating gyroscope 100. When shear strain acts on the casing of the vibrating gyroscope 100, the fixed points A1 and A2 and the fixed points B1 and B2 are rotationally displaced in the XY plane with the center of the vibrator 51 as the center of rotation. At this time, the vibrator 51 is supported by the rectangular portions 100A3 and 100A4 described above, and the support direction is the normal direction of the support plate 100A. Therefore, the shear strain acting on the vibrator 51 is extremely reduced. 51 rotates in the same direction as the rotational displacement direction of the fixed point while maintaining the shape.
Therefore, the vibrating gyroscope 100 according to the present embodiment can maintain the shape of the vibrator 51 even when shearing strain is applied, and can maintain the orthogonality between the driving direction and the detection direction so that unnecessary signals are mixed in the detection signal. Can be suppressed.

Next, simulations performed on the example of the present invention and the conventional example will be described. In the simulation, the strain amount of the shear strain was set to 0.001, the displacement of the fixed part due to the shear strain was applied to the vibrator model, and the deformation state of the vibrator model was observed by static analysis.
FIG. 11 is a diagram illustrating the results of simulating deformation due to shear strain in each of the example of the present invention and the conventional example. 11A shows a conventional vibration gyro 301, FIG. 11B shows a conventional vibration gyro 401 in which the support anchor is omitted from the same configuration as that of the second embodiment, and FIG. FIG. 11D shows the vibrating gyroscope 100 of the first embodiment, and FIG. 11D shows the vibrating gyroscope 50 of the first embodiment.
In the vibration gyros 301 and 401 of the conventional example, since the fixing point is supported on the wall surface, the support anchor is inclined in the direction opposite to the rotational displacement direction in which the fixing point of the vibrator rotates due to the action of shearing strain. Deformation has occurred. On the other hand, in the vibration gyros 50 and 100 of the embodiment, since the fixed point of the vibrator is supported by the support plate, the support anchor rotates in the same direction as the rotational displacement direction of the fixed point, and is almost deformed. Absent.

  A modal analysis in the deformation state of this simulation was performed, and the amount of shake in the detection direction during drive vibration was calculated. Then, in the vibration gyro 301 of the conventional example, the amount of shake in the detection direction at the time of driving vibration per amplitude of 3 μm is 61.0 nm, and in the vibration gyro 401 of the conventional example, the amount of shake in the detection direction at the time of drive vibration per 3 μm of amplitude. Was 147.6 nm. On the other hand, in the vibration gyro 50 of the embodiment of the present invention, the amount of shake in the detection direction at the time of drive vibration per amplitude of 3 μm is 6.1 nm, and in the vibration gyro 100, the amount of shake in the detection direction at the time of drive vibration per amplitude of 3 μm. Was 6.3 nm.

  Thus, from the modal analysis of the simulation, it can be confirmed that the amount of shake in the detection direction at the time of driving vibration is 1/10 of the conventional example in the embodiment of the present invention. It was confirmed that the deformation of the vibrator due to can be suppressed.

DESCRIPTION OF SYMBOLS 1,51 ... Vibrator 10A, 60A-60F ... Support anchor 11A, 61A-61F ... Sub-anchor 12A, 12B, 62A, 62B ... Drive beam 13A-13C, 63A-63D ... Drive mass part 14A, 14B, 64A, 64B ... Drive comb teeth 15A-15D, 16A-16D, 65 ... Detection beams 17A-17D, 67A, 67B ... Detection mass sections 18A-18D, 68A, 68B ... Detection comb teeth 19A, 19B, 69A, 69B ... Monitor comb Tooth part 2A, 2B, 72 ... Detection fixing structure part 3A, 3B, 73 ... Driving fixing structure part 4A, 4B, 74 ... Monitor fixing structure part 21, 31, 41 ... Strut part 22, 32, 42 ... Line 23, 33, 43 ... Comb electrode 5 ... Outer frame part 50, 100 ... Vibrating gyroscope 50A, 100A ... Support plate (lid plate)
50A1, 100A1 ... frame-like part 50A2, 100A2 ... cylindrical part 50A3, 100A3, 100A4 ... rectangular part 50B ... low resistance silicon plate 50C ... bottom plate A1, A2, BA, B2 ... fixed point

Claims (4)

Driving mass that vibrates by driving,
A driving beam that supports the driving mass and bends and vibrates due to a force acting from the driving mass;
A detection mass unit supported by the drive mass unit in a freely displaceable state with respect to Coriolis force acting by vibration of the drive mass unit; and
A support beam that supports the drive beam at a position that becomes a node of the flexural vibration;
A vibrator comprising:
A support plate parallel to the vibration direction of the drive mass unit and the displacement direction of the detection mass unit,
In a region that passes through the center of the vibrator and faces a center line parallel to the vibration direction, the vibrator is fixed to the support plate.
Vibration gyro.   The vibrating gyroscope according to claim 1, wherein the support beam has a linear beam shape orthogonal to the center line.   The vibrating gyroscope according to claim 1, wherein the support beam and the driving beam are connected by a connecting portion that is bent in a meander line shape. An outer frame portion that houses the vibrator inside the opening, and a lid plate and a bottom plate that close the opening of the outer frame portion,
The vibration gyro according to claim 1, wherein the outer main surface of the bottom plate is a mounting surface, and only the lid plate is joined to the vibrator to form the support plate.

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