JP2014085210A - Angular velocity sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity sensor which is capable of stabilizing the operation while improving element sensitivity with a voltage value of a driving signal equal to or higher than a prescribed voltage.SOLUTION: A piezoelectric layer 9 shows such hysteresis characteristics that, when a voltage value of a driving signal applied to four vibration excitation electrodes 11 is equal to or higher than a prescribed voltage, a gain being a ratio of an output voltage of a displacement detection part to the voltage value becomes a maximum value at a first frequency by continuously increasing the frequency of the driving signal and is reduced by furthermore increasing the frequency and then becomes the maximum value at a second resonance frequency lower than the first frequency by decreasing the frequency of the driving signal. Setting is performed so that the driving signal which has a frequency lower than and close to the second resonance frequency and has the voltage value of the prescribed voltage or higher is applied to the four vibration excitation electrodes 11.

Description

  The present invention relates to an angular velocity sensor device.

  For example, when an angular velocity sensor of the type disclosed in Japanese Patent Laid-Open No. 2010-160095 (Patent Document 1) is used, it is also disclosed in paragraphs [0068] to [0074] of Japanese Patent Laid-Open No. 2010-160095. Thus, as a method for increasing the detection sensitivity (element sensitivity) of an element, (1) increasing the mass of the weight (vibrator), (2) increasing the movement speed of the weight, (3) vibration It has been known to design the axial resonance frequency and the displacement axial resonance frequency as close as possible to increase the displacement caused by the Coriolis force.

JP 2010-160095 A

  The inventors have found that in the angular velocity sensor device, the element sensitivity can be improved by increasing the voltage value of the drive signal applied to the vibration inducing portion that induces vibration. When the resonance frequency is defined as a frequency indicating the minimum impedance (maximum admittance), the vibration amplitude becomes maximum at the resonance frequency when driven by an AC voltage having the same amplitude. However, when the voltage value of the drive signal is equal to or higher than a predetermined voltage, the resonance frequency when the drive signal frequency is swept from low to high is the first resonance frequency, and the drive signal frequency is high to low. Assuming that the resonance frequency when swept to the second resonance frequency is the second resonance frequency, it has been found that there is an angular velocity sensor exhibiting a hysteresis characteristic in which the second resonance frequency is lower than the first resonance frequency. More specifically, in this type of angular velocity sensor, when the frequency of the drive signal is swept from low to high, the gain that is the ratio of the output voltage of the displacement detector to the voltage value at the first resonance frequency is the maximum value. When the frequency is further increased, the gain is decreased. Thereafter, when the frequency of the drive signal is swept from higher to lower, the gain becomes the maximum value at the second resonance frequency lower than the first resonance frequency. Show properties. For this reason, with this type of angular velocity sensor, there is a problem that the operation becomes unstable within the range where hysteresis characteristics occur, and oscillation stops in the case of self-excited oscillation.

  An object of the present invention is to provide an angular velocity sensor device that can stabilize the operation while increasing the element sensitivity by setting the voltage value of the drive signal to a predetermined voltage or higher.

  An angular velocity sensor device to which the present invention is directed includes a flexible elastic substrate, a piezoelectric layer formed on the flexible elastic substrate, and a plurality of piezoelectric layers that vibrate when provided and driven on the piezoelectric layer. Displacement detection, which includes a plurality of vibration excitation electrodes and a plurality of angular velocity detection electrodes provided on the piezoelectric layer, and detects displacement induced by vibration and external angular velocity by the output of the plurality of angular velocity detection electrodes An angular velocity sensor including a unit, and a drive circuit that applies a drive signal to a plurality of vibration excitation electrodes in order to excite vibration.

  In the present invention, as the voltage value of the drive signal, when the frequency of the drive signal is swept from the lower side to the higher side, the resonance frequency is the first resonance frequency, and when the frequency of the drive signal is swept from the higher side to the lower side When the resonance frequency of the second resonance frequency is the second resonance frequency, a voltage value equal to or higher than a predetermined voltage showing a hysteresis characteristic in which the second resonance frequency is lower than the first resonance frequency is used. In the present invention, the drive signal output from the drive circuit is set to a frequency lower than the second resonance frequency that has a voltage value equal to or higher than a predetermined voltage and avoids a region exhibiting hysteresis characteristics.

  In the present specification, this hysteresis characteristic is defined as “frequency hysteresis”. In the present specification, the resonance frequency is a frequency at which the amplitude of vibration becomes the largest as described above.

  By setting the voltage and frequency of the drive signal applied to the vibration excitation electrode in this manner, it is possible to avoid a frequency region in which frequency hysteresis that is unsuitable for driving occurs while improving device sensitivity. Therefore, both improvement in element sensitivity and stable operation can be achieved.

  More specifically, the angular velocity sensor device to which the present invention is directed is formed on a diaphragm, a flat diaphragm, a weight disposed at the center of the diaphragm, a support part that supports the outer periphery of the diaphragm, and the diaphragm. And a plurality of vibration excitation electrodes provided for the piezoelectric layer, and when a drive signal is applied to the plurality of vibration excitation electrodes, The direction of the displacement axis that occurs in the weight based on the Coriolis force, including a vibration excitation unit that induces vibration with a motion component in the direction of the vibration axis, and a plurality of electrodes for detecting the angular velocity provided for the piezoelectric layer An angular velocity sensor including a displacement detection unit that detects the displacement of the angular velocity based on voltages appearing on the plurality of angular velocity detection electrodes, and a drive circuit that applies a drive signal to the plurality of vibration excitation electrodes of the angular velocity sensor. . The angular velocity sensor has an origin O at the center position of the diaphragm, and when an XYZ three-dimensional orthogonal coordinate system in which the surface of the diaphragm is included in the XY plane is defined, one of the X axis and the Z axis is a vibration axis, The other is the displacement axis, and the angular velocity around the Y axis is detected based on the detection value from the displacement detector.

  In particular, in the present invention, when the angular velocity sensor continuously increases the frequency of the drive signal from the lower to the higher when the voltage value of the drive signal applied to the plurality of vibration excitation electrodes is a predetermined voltage or higher. The gain, which is the ratio of the output voltage of the displacement detector to the voltage value at the first resonance frequency, becomes the maximum value, and the gain decreases as the frequency is further increased, and then the frequency of the drive signal is increased from the higher to the lower one. When swept, the hysteresis characteristic is such that the gain becomes the maximum value at the second resonance frequency lower than the first resonance frequency. In the present invention, the drive circuit is set to apply a drive signal having a frequency lower than the second resonance frequency and close to the second resonance frequency and having a voltage value equal to or higher than a predetermined voltage.

  By setting the voltage and frequency of the drive signal applied to the vibration excitation electrode in this manner, it is possible to avoid a frequency region in which frequency hysteresis that is unsuitable for driving occurs while improving device sensitivity. Therefore, both improvement in element sensitivity and stable operation can be achieved.

  It has been found that if the frequency of the drive signal is lower than the second resonance frequency, the vibration due to the drive is stable, but if it is too low, the vibration becomes smaller and the element sensitivity is lowered. Therefore, in the present invention, the frequency of the drive signal is set to a frequency lower than the second resonance frequency and a frequency at which an element sensitivity higher than the element sensitivity obtained from the voltage value of the drive signal at which no hysteresis characteristic appears. desirable. By setting in this way, the device sensitivity can be improved reliably.

(A)-(C) are the top view of an example of embodiment of the angular velocity sensor used for the angular velocity sensor apparatus of this invention, a bottom view, and sectional drawing. It is a block diagram of an embodiment of an angular velocity sensor device of the present invention. It is a wave form diagram which shows the gain obtained when a frequency is swept from low to high, and a frequency is swept from high to low after that. It is a figure which shows the detection output at the time of changing the frequency of a drive signal in the frequency range of 0%-4% on the basis of the 2nd resonance frequency, (A) is pitch (around Y-axis), ( B) is a view of a roll (around the X axis). It is a figure which shows the element sensitivity at the time of changing the frequency of a drive signal in the frequency range of 0%-4% on the basis of the 2nd resonance frequency, and an element sensitivity change rate, (A) is pitch (Y (Axis rotation) and (B) are views of a roll (X axis rotation). It is a figure which shows the other-axis sensitivity at the time of changing the frequency of a drive signal in the frequency range of 0%-4% on the basis of the 2nd resonance frequency, (A) is a pitch (around Y-axis), (B) is a view of a roll (around the X axis). It is a figure which shows element sensitivity when the frequency of a drive signal is lowered by 2% from the second resonance frequency when the voltage value of the drive signal is 0.8 Vpp, 1.0 Vpp, and 1.2 Vpp. These are figures of a pitch (around the Y axis) and (B) a roll (around the X axis).

  Hereinafter, an example of an embodiment of a power storage device of the present invention will be described with reference to the drawings.

  In the angular velocity sensor GS used in the angular velocity sensor device GM of the present invention, a flat diaphragm 1, a weight 3 disposed at the center of the diaphragm 1, a support portion 5 that supports the outer peripheral portion of the diaphragm, and the surface of the diaphragm A lower electrode 7 formed through an insulating film 6, a piezoelectric thin film (piezoelectric layer) 9 formed on the lower electrode, four vibration excitation electrodes 11 formed on the piezoelectric thin film 9, and Four angular velocity detection electrodes 13 are provided. The diaphragm 1 constitutes a flexible elastic substrate. The diaphragm 1, the weight 3, and the support 5 have a mask having a shape corresponding to the end face of the weight 3 and the end face of the support 5 on one surface of the semiconductor substrate having a crystal orientation (100). These are integrally formed by dry etching from the mask side. In the present embodiment, the four vibration excitation electrodes 11 constitute a vibration excitation unit that induces vibration having a motion component in the direction of a predetermined vibration axis with respect to the weight 3. Further, the angular velocity detection electrode 13 constitutes a displacement detector that detects a displacement in the direction of the displacement axis generated in the weight 3 based on the Coriolis force.

  In order to induce a vibration having a motion component in the direction of a predetermined vibration axis with respect to the weight 3, a vibration excitation unit including four vibration excitation electrodes 11 is driven with an alternating voltage. The displacement in the direction of the displacement axis generated in the weight 3 based on the Coriolis force is detected by the voltages generated in the four angular velocity detection electrodes 13 to obtain the angular velocity. In this angular velocity sensor, when an XYZ three-dimensional orthogonal coordinate system in which the origin O is at the center position of the diaphragm 1 and the surface of the diaphragm 1 is included in the XY plane is defined, one of the X axis and the Z axis is defined. Using the vibration axis and the other as the displacement axis, the angular velocity around the Y axis is detected based on the detection value from the angular velocity detection electrode 13 constituting the displacement detector. In order to detect angular velocities around the X axis and the Y axis, the weight 3 is vibrated in the Z direction. In order to detect the angular velocity around the Z axis, the weight 3 is vibrated in the X axis direction or the Y axis direction.

  The weight 3 has a columnar shape or a conical shape. And the outline shape of the outer peripheral part of a diaphragm is a shape which has the linear part SL in the four corners of a quadrangle (substantially square in this Embodiment). In the present embodiment, a small rounded portion is formed at the intersection of each of the square sides S1 to S4 and the straight line portion SL.

  In the angular velocity sensor of the present embodiment, four vibration excitation electrodes 11 are formed in four regions partitioned by a first virtual diagonal line CL1 and a second virtual diagonal line CL2, respectively. The four angular velocity detection electrodes 13 are also formed in four regions partitioned by the first virtual diagonal line CL1 and the second virtual diagonal line CL2, respectively. In the present embodiment, the first imaginary line L1 and the second imaginary line L2 coincide with the X-axis axis and the Y-axis axis, respectively. In such an arrangement, the length dimension that follows the second imaginary line of the diaphragm outline is R1, the length dimension that follows the first imaginary line of the diaphragm outline is R2, and the first imaginary diagonal and second R1: R2: R3 = (value in the range of 0.95 ± 0.02): 1: (value in the range of 0.85 ± 0.02) where R3 is the length dimension along the virtual diagonal of It has been experimentally confirmed that both the main axis sensitivity and the other axis sensitivity can be balanced by satisfying the above relationship. In the present embodiment, the four vibration excitation electrodes 11 include an outer side 12A located on the outer side in the radial direction of the weight 3, an inner side 12B that faces the outer side 12A in the radial direction, and an outer side 12A. It consists of a pair of connecting sides 12C and 12D that connect the inner side 12B. The shape of the outer side 12A is similar to the shape of a part of the outer peripheral part of the diaphragm 1 (a part extending between two adjacent sides SL and the straight line part S1). The shape of the inner side 12B of the contour shape of the vibration excitation electrode 11 has an arc shape. It has been confirmed that when the four vibration excitation electrodes 11 have such a shape, vibration can be generated most efficiently and stably. The contour shapes of the four angular velocity detection electrodes 13 are as follows: an outer side 14A located on the radially outer side of the weight 3, an inner side 14B that faces the outer side 14A in the radial direction, an outer side 14A, and an inner side 14B. It comprises a pair of connecting sides 14C and 14D that connect the two. In the present embodiment, the outer side 14A and the inner side 14B each have a concentric arc shape. When the four vibration excitation electrodes 11 and the four angular velocity detection electrodes 13 are determined in this way, a signal capable of classifying the vibration in the X-axis direction and the vibration in the Y-axis direction is reliably obtained from the four angular velocity detection electrodes 13. It has been confirmed that it can. In the present embodiment, [the part indicated by r in FIG. 1A] the corners of the four vibration excitation electrodes 11 and the four angular velocity detection electrodes 13 are curved, so that the electrodes are peeled off. Can be effectively prevented. Further, in the present embodiment, since the connecting portion [the portion indicated by r in FIG. 1B] between the edge and the corner of the outline of the diaphragm 1 is curved, the mechanical strength of the diaphragm 1 is high.

  FIG. 2 is a block diagram of the angular velocity sensor device GM of the present embodiment. The angular velocity sensor device GM of the present embodiment is roughly composed of the above-described angular velocity sensor GS and a driving device DC that drives the angular velocity sensor GS. The drive device DC attenuates frequencies other than a predetermined frequency of the output of the oscillation circuit 21 that generates a drive signal to be input to the vibration excitation electrode 11, an amplifier 23 that amplifies the output of the angular velocity detection electrode 13, and the output of the amplifier 23. It comprises a band pass filter 25 and a gain comparator 27. The gain comparator 27 drives the angular velocity sensor GS at a predetermined frequency to compare the gain of the voltage output from the bandpass filter 25 with the gain of the voltage output from the bandpass filter 25 by decrementing the frequency. It has a function of determining the second resonance frequency. The phase comparator 29 will be described later.

  A drive signal applied to the vibration excitation electrode 11 in this embodiment will be described with reference to FIG. In the present embodiment, in order to detect angular velocities around the X axis and the Y axis, the weight 3 is vibrated in the Z direction and measurement is performed. In FIG. 3, the horizontal axis represents the frequency [kHz] of the drive signal, and the vertical axis represents the gain (ratio of the output voltage of the displacement detector to the voltage value of the applied drive signal) [dB]. In FIG. 2, the gain characteristics (sweep up 1 Vpp and sweep down 1 Vpp) of the drive signal of the present embodiment and the gain characteristics (sweep up 0.5 Vpp) of the drive signal used in the conventional angular velocity sensor device are compared for comparison. (Sweep down 0.5Vpp) is also shown.

  In the conventional angular velocity sensor device, in order to stabilize the operation, even when the frequency of the drive signal is changed, a voltage value at which the gain does not exhibit hysteresis characteristics is used. In the case of the angular velocity sensor GS, an example of this voltage value is 0.5 Vpp. As shown in FIG. 3, when the frequency is continuously increased (sweep from low to high [sweep up]), The gain increases, and the maximum gain is -4.0 dB at 34.42 kHz, and the gain continuously decreases. The frequency indicating the maximum value, that is, the frequency at which the amplitude is maximum is the “resonance frequency”. After that, when the frequency is continuously lowered (when swept down from higher to lower [sweep down]), the gain increases, as in the case where the frequency is continuously raised, at -4 at 34.42 kHz. The gain decreases continuously with 0.0 dB as the maximum value. Since the change in gain when the frequency is continuously increased and when the frequency is continuously decreased is substantially the same, in FIG. 3, the two waveforms are displayed so as to overlap each other.

  The drive signal applied to the angular velocity sensor GS of the present embodiment uses a voltage value having a region where the gain exhibits hysteresis characteristics when the frequency is continuously increased and then continuously decreased. In the case of the angular velocity sensor GS of the present embodiment, an example of this voltage value is 1.0 Vpp. As shown in FIG. 3, when the frequency is continuously increased (sweep up), the gain increases, and -4.1 dB at the time of 34.91 kHz (first resonance frequency) is maximized. Immediately after exceeding .92 kHz, the gain exhibits a characteristic of rapidly decreasing. After that, when the frequency is continuously lowered (sweep down), the gain increases rapidly when it exceeds 34.83 kHz, and when the frequency is immediately after 34.82 kHz (second resonance frequency), the frequency is decreased. It becomes -4.4 dB which is the maximum value of the gain when continuously lowered. As is apparent from FIG. 3, when the voltage value is 1.0 Vpp, the gain exhibits a hysteresis characteristic with respect to the frequency. This characteristic is due to the non-linear characteristic of the elastic body and the piezoelectric thin film, and is presumed to be particularly due to the non-linear effect of the piezoelectric thin film. In the present specification, this hysteresis characteristic is defined as “frequency hysteresis”. FIG. 3 is an example, and the frequency change, gain, hysteresis region, and the like may be different.

  In the present embodiment, in order to realize stable driving using a driving signal having a voltage value (1.0 Vpp) indicating the frequency hysteresis shown in FIG. 3, in order to avoid a frequency region in which frequency hysteresis occurs, The frequency is set to be lower than the second resonance frequency. 4 to 6 show changes in each element when the frequency of the drive signal is changed in the frequency range of 0% to 4% with reference to the second resonance frequency. 4A to 6A, (A) is a case (pitch) in which the weight 3 is vibrated in the Z-axis direction and the angular velocity around the Y-axis is detected using the X-axis as the displacement axis. ) Is a case (roll) in which the weight 3 is vibrated in the Z-axis direction and the angular velocity around the X-axis is detected using the Y-axis as the displacement axis.

  4A and 4B are diagrams showing the detection output [mVpp] when the frequency of the drive signal is changed in the frequency range of 0% to 4% with reference to the second resonance frequency. . Legend symbols X1, X2, Y1, and Y2 correspond to the symbols attached to the four vibration excitation electrodes 11 in FIG. 1A, and the data surrounded by dotted circles indicate the voltage values of the drive signals. Data for comparison when 0.5 Vpp is set. If it is between 0% and 2%, when the voltage value of the drive signal is 1.0 Vpp, the voltage value of the drive signal is 0.5 Vpp in all four vibration excitation electrodes 11. It can be seen that the detection output is higher than that.

  5A and 5B show device sensitivity [μV / dps] and device sensitivity when the frequency of the drive signal is changed in the frequency range of 0% to 4% with reference to the second resonance frequency. It is a figure which shows change rate [%]. Data enclosed by a dotted circle is data for comparison when the voltage value of the drive signal is 0.5 Vpp. 5A and 5B, when the voltage value of the drive signal is 1.0 Vpp, the voltage value of the drive signal is 0.5 Vpp when the voltage value is approximately 0% to 1.5%. It can be read that the device sensitivity is higher than in the case of the above.

  FIGS. 6A and 6B are diagrams showing other-axis sensitivity [%] when the frequency of the drive signal is changed in a frequency range of 0% to 4% with reference to the second resonance frequency. is there. Data enclosed by a dotted circle is data for comparison when the voltage value of the drive signal is 0.5 Vpp. 6A and 6B, when the voltage value of the drive signal is 1.0 Vpp between 0% and 2%, compared to the case where the voltage value of the drive signal is 0.5 Vpp, It can be seen that the sensitivity of other axes does not deteriorate.

  From the above experimental results, when the voltage value of the drive signal is 1.0 Vpp, in this embodiment, the frequency of the drive signal is a frequency within 1.5% from the second resonance frequency in order to stabilize the operation. The frequency is determined within the range. However, since the angular velocity sensor GS is easily affected by temperature, changes with time, etc., this frequency range is only an example, and when the voltage value of the drive signal is 1.0 Vpp as shown in FIG. Is based on setting the frequency of the drive signal within 2% of the second resonance frequency.

  FIG. 7 shows device sensitivity when the frequency of the drive signal is lowered by 2% from the second resonance frequency when the voltage value of the drive signal is set to 0.8 Vpp, 1.0 Vpp, and 1.2 Vpp at which frequency hysteresis occurs. It is the figure which showed [microvolt / dps]. (A) is a case where the weight 3 is vibrated in the Z-axis direction and the angular velocity around the Y-axis is detected using the X-axis as the displacement axis (pitch), and (B) is the weight 3 in the Z-axis direction. When the angular velocity around the X axis is detected with the Y axis as the displacement axis (roll). 7A and 7B, in this case, when the voltage value of the drive signal is 0.8 Vpp, it is lower than that at 0.5 Vpp, whereas 1.0 Vpp and In the case of 1.2 Vpp, it can be seen that even if the frequency is lowered by 2%, it can be made higher than that in the case of 0.5 Vpp. Therefore, it is determined how much the frequency of the drive signal is lowered from the second resonance frequency according to the voltage value of the drive signal and the environment in which the angular velocity sensor device GM is used.

  As described above, in the present invention, the device sensitivity can be improved and the operation can be stabilized by using the drive signal having the voltage value and frequency determined from the following steps.

(1) Applying a drive signal having a voltage value indicating frequency hysteresis to continuously increase the frequency of the drive signal (this operation may not be necessary), and then decreasing the frequency continuously to compare the gain. The second resonance frequency is found by means of the device 27. When finding the second resonance frequency, the graph of FIG. 3 may be displayed on a display screen (not shown) and found by visual observation.

(2) A frequency that is lower than the second resonance frequency and within an appropriate frequency range within several percent of the second resonance frequency is determined.

  The above steps are performed in advance for the angular velocity sensor device GM, and the angular velocity sensor device can be easily used if the voltage value and frequency of the drive signal are determined in advance. In addition, when using it, the above steps are executed as necessary (for example, at regular intervals, at startup, when the temperature changes, etc.), and the voltage value and frequency of the drive signal are determined (calibration is performed). Of course. In this way, it is possible to use an appropriate drive signal that matches the environment and situation.

  The above numerical value is an example, and the numerical value changes due to different conditions and environments. In particular, since it is known that the characteristics of an angular velocity sensor may change depending on the environmental temperature, a change due to temperature is expected. Even in such a case, the device sensitivity can be improved and the operation can be stabilized by determining the voltage value and frequency of the drive signal by the same process as in the present invention. In the present embodiment, a phase comparator 29 is further provided in the drive circuit DC in order to stabilize the operation. The phase comparator 29 compares the phase of the output voltage of the oscillation circuit 21 with the phase of the output voltage of the bandpass filter 25, and from the initial state (vibration state at the frequency of the drive signal determined by calculation from the gain). A feedback signal for correcting the frequency of the output voltage of the oscillation circuit 21 is generated so as not to shift the phase. In this way, by controlling the oscillation circuit 21 based on the feedback signal, it is possible to prevent a phase shift caused by a change in temperature and time and maintain the initial state.

  In the present embodiment, the shape and electrode arrangement of the angular velocity sensor are the same as those shown in FIGS. 1A to 1C. However, the shape and electrode arrangement of the angular velocity sensor are not limited to this. Absent. Even with other materials and other shapes and electrode arrangements, the device sensitivity can be improved and the operation can be stabilized by determining the voltage value and frequency of the drive signal by the same process as in the present invention. it can.

  According to the present invention, it is possible to obtain an angular velocity sensor device capable of stabilizing the operation by increasing the voltage value of the drive signal to improve element sensitivity and using a frequency in a region where no frequency hysteresis occurs. .

GM Angular velocity sensor device GS Angular velocity sensor 1 Diaphragm 3 Weight 5 Support part 6 Insulating film 7 Lower electrode 9 Piezoelectric thin film (piezoelectric layer)
11 vibration excitation electrode 12A outer side 12B inner side 12C, 12D connecting side 13 angular velocity detection electrode 14A outer side 14B inner side 14C, 14D connecting side S1 to S4 side CL1 first virtual diagonal line CL2 second virtual diagonal line L1 first 1 virtual line L2 2nd virtual line DC drive circuit 21 oscillation circuit 23 amplifier 25 band pass filter 27 gain comparator 29 phase comparator

Claims (3)

A flexible elastic substrate;
A piezoelectric layer formed on the flexible elastic substrate;
A plurality of vibration excitation electrodes that vibrate the piezoelectric layer and the flexible elastic substrate when provided and driven on the piezoelectric layer;
A displacement detector configured to include a plurality of detection electrodes provided on the piezoelectric layer, and to detect a displacement induced by the vibration and an external angular velocity by an output of the plurality of angular velocity detection electrodes. Angular velocity sensor,
An angular velocity sensor device comprising a drive circuit that applies a drive signal to the plurality of vibration excitation electrodes to excite the vibration,
When the angular velocity sensor sweeps the frequency of the drive signal from low to high when the voltage value of the drive signal applied to the plurality of vibration excitation electrodes is equal to or higher than a predetermined voltage, a resonance frequency is obtained. When the resonance frequency when the drive signal frequency is swept from higher to lower is the second resonance frequency, the second resonance frequency is higher than the first resonance frequency. Shows lower hysteresis characteristics,
The drive signal output from the drive circuit is set to a frequency lower than the second resonance frequency having a voltage value equal to or higher than the predetermined voltage and avoiding a region exhibiting the hysteresis characteristic. An angular velocity sensor device. A flat diaphragm,
A weight disposed in the center of the diaphragm;
A support portion for supporting an outer peripheral portion of the diaphragm;
A piezoelectric layer formed on the diaphragm;
A plurality of vibration excitation electrodes provided for the piezoelectric layer, and when a drive signal is applied to the plurality of vibration excitation electrodes, a direction of a predetermined vibration axis with respect to the weight A vibration excitation part for inducing vibrations having a motion component of
A plurality of detection electrodes provided for the piezoelectric layer, and detecting displacement in a direction of a displacement axis generated in the weight based on Coriolis force based on voltages appearing on the plurality of angular velocity detection electrodes; A displacement detector,
When an XYZ three-dimensional orthogonal coordinate system having an origin O at the center position of the diaphragm and a surface of the diaphragm included in an XY plane is defined, one of the X axis and the Z axis is the vibration axis, An angular velocity sensor that detects the angular velocity around the Y axis based on a detection value from the displacement detector, the other being the displacement axis;
An angular velocity sensor device comprising: a drive circuit that applies the drive signal to the plurality of vibration excitation electrodes of the angular velocity sensor;
When the angular velocity sensor sweeps the frequency of the drive signal from lower to higher when the voltage value of the drive signal applied to the plurality of vibration excitation electrodes is equal to or higher than a predetermined voltage, the first resonance frequency The gain, which is the ratio of the output voltage of the displacement detector to the voltage value, reaches a maximum value, and further increases the frequency, the gain decreases, and then the drive signal frequency is swept from higher to lower Then, it shows a hysteresis characteristic in which the gain reaches a maximum value at a second resonance frequency lower than the first resonance frequency,
The angular velocity sensor device, wherein the drive circuit applies the drive signal having a frequency lower than the second resonance frequency and close to the second resonance frequency and having a voltage value equal to or higher than the predetermined voltage.   The angular velocity sensor device according to claim 1, wherein the frequency of the drive signal is a frequency at which an element sensitivity higher than an element sensitivity obtained by a voltage value of the drive signal at which the hysteresis characteristic does not appear.

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