Gyro sensor

Abstract

A gyro sensor according to the present invention comprises a first angular velocity detection unit and a control unit. The first angular velocity detection unit has a first vibrator and a plurality of first electrodes. The control unit comprises a first addition circuit that outputs a first addition signal that is the sum of a first detection signal and a second detection signal. The component of the second detection signal that corresponds to the angular velocity applied to the first vibrator has the opposite phase of the component of the first detection signal that corresponds to the angular velocity applied to the first vibrator. A first failure diagnosis unit determines failure of the gyro sensor on the basis of the first addition signal and outputs a first determination results signal.

Description

Gyro sensor

[0001] The present disclosure relates generally to gyro sensors, and more particularly to a gyro sensor having a function for self-diagnosing a fault.

[0002] The sensing device (gyro sensor) described in Patent Document 1 detects angular velocity. The sensing device includes a MEMS (Micro Electro Mechanical Systems) gyroscope (vibrator), a rate feedback loop, a quadrature feedback loop, and a test signal generator. The MEMS gyroscope is coupled to the rate feedback loop and the quadrature feedback loop. The test signal generator generates a test signal. The test signal is injected into the rate feedback loop, then fed back to the MEMS gyroscope, and finally detected from the quadrature feedback loop. This allows the sensing device to monitor the entire system.

[0003] US Patent Application Publication No. 2014 / 250970

[0004] In order to perform fault diagnosis, the sensing device (gyro sensor) described in Patent Document 1 requires a test signal generator that generates test signals that are not related to the original functions of the sensing device itself, other than signals based on the detected angular velocity and signals related to driving the MEMS gyroscope.

[0005] A gyro sensor according to one aspect of the present disclosure includes a first angular velocity detection unit and a control unit. The first angular velocity detection unit has a first vibrator and a plurality of first electrodes. The plurality of first electrodes are arranged to face the first vibrator and form a capacitance between the first vibrator and the first electrodes. The control unit is electrically connected to the plurality of first electrodes. The plurality of first electrodes include a first drive electrode to which a drive signal for driving the first vibrator is applied, a first angular velocity detection electrode whose capacitance with the first vibrator changes in response to detection vibration of the first vibrator caused by application of an angular velocity to the first vibrator, a second angular velocity detection electrode whose capacitance with the first vibrator changes in response to the detection vibration of the first vibrator caused by application of the angular velocity to the first vibrator, and a first transport electrode to which a carrier signal is applied. The control unit includes a drive control unit that applies the drive signal to the first drive electrodes, a carrier wave forming unit that applies the carrier signal to the first carrier electrodes, a first angular velocity processing unit that generates a first angular velocity signal according to the angular velocity applied to the first vibrator, and a first fault diagnosis unit, wherein the frequency of the carrier signal is higher than the frequency of the drive signal. the first angular velocity processing unit includes: a first connection circuit electrically connected to the first angular velocity detection electrode and configured to output, as a first detection signal, a signal corresponding to a capacitance between the first vibrator and the first angular velocity detection electrode; a second connection circuit electrically connected to the second angular velocity detection electrode and configured to output, as a second detection signal, a signal corresponding to a capacitance between the first vibrator and the second angular velocity detection electrode; a first subtraction circuit configured to output a first differential signal that is a difference between the first detection signal and the second detection signal; a first addition circuit configured to output a first addition signal that is a sum of the first detection signal and the second detection signal; and a first angular velocity calculation unit configured to generate the first angular velocity signal based on the first differential signal. A component included in the second detection signal that corresponds to the angular velocity applied to the first vibrator is in antiphase with a component included in the first detection signal that corresponds to the angular velocity applied to the first vibrator.The first failure diagnosis unit determines whether the gyro sensor has a failure based on the first addition signal, and outputs a first determination result signal.

[0006] The present disclosure has an advantage in that fault diagnosis in a gyro sensor is possible without using a test signal.

[0007] Fig. 1 is a block diagram of a gyro sensor according to embodiment 1. Fig. 2 is a block diagram of a gyro sensor according to embodiment 2. Fig. 3 is a block diagram of a gyro sensor according to embodiment 3. Fig. 4 is a block diagram of a gyro sensor according to embodiment 4.

[0008] In the following embodiments, the gyro sensor of the present disclosure will be described with reference to the drawings. However, the following embodiments are merely a part of various embodiments of the present disclosure. The following embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, the following embodiments, including modified examples, may be realized in appropriate combinations.

[0009] In this disclosure, applying a voltage signal to an object means applying a voltage signal between the object and a structure maintained at a reference potential (eg, ground).

[0010] (1) Embodiment 1 (1.1) Overview As shown in Fig. 1 , a gyro sensor X1 of this embodiment includes a first angular velocity detection unit 1 and a control unit 30. The first angular velocity detection unit 1 has a first vibrator 10 and a plurality of first electrodes. The plurality of first electrodes are arranged to face the first vibrator 10, and form electrostatic capacitance between the first vibrator 10 and the first electrodes. The control unit 30 is electrically connected to the plurality of first electrodes. The plurality of first electrodes include a first drive electrode 13 to which a drive signal D1 for driving and vibrating the first vibrator 10 is applied, a first angular velocity detection electrode 11 whose capacitance with the first vibrator 10 changes in response to detection vibration of the first vibrator 10 caused by application of an angular velocity to the first vibrator 10, a second angular velocity detection electrode 12 whose capacitance with the first vibrator 10 changes in response to detection vibration of the first vibrator 10 caused by application of an angular velocity to the first vibrator 10, and a first transport electrode 14 to which a carrier signal H1 is applied. The control unit 30 includes a drive control unit 31 that applies the drive signal D1 to the first drive electrode 13, a carrier wave forming unit 32 that applies the carrier signal H1 to the first transport electrode 14, a first angular velocity processing unit 4 that generates a first angular velocity signal ω1 corresponding to the angular velocity applied to the first vibrator 10, and a first fault diagnosis unit 5. The frequency of the carrier signal H1 is higher than the frequency of the drive signal D1. The first angular velocity processing unit 4 includes a first connection circuit 41 electrically connected to the first angular velocity detection electrode 11 and outputting a signal corresponding to the capacitance between the first vibrator 10 and the first angular velocity detection electrode 11 as a first detection signal V1, a second connection circuit 42 electrically connected to the second angular velocity detection electrode 12 and outputting a signal corresponding to the capacitance between the first vibrator 10 and the second angular velocity detection electrode 12 as a second detection signal V2, a first subtraction circuit 44 outputting a first differential signal S1 which is the difference between the first detection signal V1 and the second detection signal V2, a first addition circuit 43 outputting a first sum signal A1 which is the sum of the first detection signal V1 and the second detection signal V2, and a first angular velocity calculation unit 45 which generates a first angular velocity signal ω1 based on the first differential signal S1.The component of the second detection signal V2 corresponding to the angular velocity applied to the first vibrator 10 is in opposite phase to the component of the first detection signal V1 corresponding to the angular velocity applied to the first vibrator 10. The first fault diagnosis unit 5 determines a fault in the gyro sensor X1 based on the first addition signal A1, and outputs a first determination result signal R1.

[0011] According to the above configuration, fault diagnosis (fault determination) is possible without using a test signal. Therefore, the circuit for generating the test signal can be omitted, thereby reducing the circuit area of ​​the gyro sensor X1. Furthermore, circuit noise can be reduced compared to when a test signal is applied to the circuit.

[0012] Furthermore, even if the frequency of the drive signal D1 is low, the frequency of the signals input to the first connection circuit 41 and the second connection circuit 42 is a relatively high frequency corresponding to the carrier signal H1, so that signal attenuation in the first connection circuit 41 and the second connection circuit 42 can be suppressed.

[0013] (1.2) Details The gyro sensor X1 of this embodiment will be described in more detail below.

[0014] (1.2.1) First Angular Velocity Detection Unit As described above, the first angular velocity detection unit 1 includes the first vibrator 10 and a plurality of first electrodes. The plurality of first electrodes includes a first drive electrode 13, a first angular velocity detection electrode 11, a second angular velocity detection electrode 12, and a first transport electrode 14.

[0015] The first vibrator 10 is formed of a material containing, for example, single crystal silicon or polycrystalline silicon, etc. The shape of the first vibrator 10 is, for example, a rectangular plate or a disk.

[0016] The plurality of first electrodes are arranged around the first vibrator 10 with a gap between them. Each of the plurality of first electrodes has a facing surface facing the first vibrator 10.

[0017] A drive signal D1 is applied to the first drive electrode 13. The drive signal D1 is an AC signal. As an example, the waveform of the drive signal D1 is a square wave. However, the waveform of the drive signal D1 may be a sine wave. The frequency of the drive signal D1 matches the resonant frequency of the first vibrator 10.

[0018] When a drive signal D1 is applied to the first drive electrode 13, the first vibrator 10 periodically vibrates (expands and contracts) due to the electrostatic force between the first vibrator 10 and the first drive electrode 13. This vibration is referred to as drive vibration in this disclosure.

[0019] The first vibrator 10 is disposed between the first angular velocity detection electrode 11 and the second angular velocity detection electrode 12 .

[0020] If an angular velocity is applied to first oscillator 10 while first oscillator 10 is being driven to vibrate, Coriolis force causes first oscillator 10 to resonate (vibrate for detection). Then, the distance between first oscillator 10 and first angular velocity detection electrode 11 changes in accordance with the angular velocity applied to first oscillator 10, and the capacitance between first oscillator 10 and first angular velocity detection electrode 11 changes. First connection circuit 41 of first angular velocity processing unit 4 outputs first detection signal V1 (voltage signal) in accordance with the capacitance between first oscillator 10 and first angular velocity detection electrode 11.

[0021] When an angular velocity is applied to the first oscillator 10 while the first oscillator 10 is being driven to vibrate, the Coriolis force causes the first oscillator 10 to resonate (vibrate for detection). Then, the distance between the first oscillator 10 and the second angular velocity detection electrode 12 changes in response to the angular velocity applied to the first oscillator 10, causing a change in the capacitance between the first oscillator 10 and the second angular velocity detection electrode 12. The second connection circuit 42 of the first angular velocity processing unit 4 outputs a second detection signal V2 (voltage signal) corresponding to the capacitance between the first oscillator 10 and the second angular velocity detection electrode 12. The first detection signal V1 and the second detection signal V2 are signals corresponding to the magnitude of the angular velocity applied to the first oscillator 10.

[0022] A carrier signal H1 output from the carrier wave generating unit 32 is applied to the first transport electrode 14. The carrier signal H1 is an AC signal. As an example, the waveform of the carrier signal H1 is a square wave. However, the waveform of the carrier signal H1 may also be a sine wave.

[0023] The frequency of the carrier signal H1 is higher than the frequency of the drive signal D1. For example, the frequency of the drive signal D1 is 40 kHz, and the frequency of the carrier signal H1 is 900 kHz.

[0024] The first vibrator 10 is disposed between the first drive electrode 13 and the first transport electrode 14 .

[0025] (1.2.2) Control Unit As described above, the control unit 30 includes the drive control unit 31, the carrier wave forming unit 32, the first angular velocity processing unit 4, and the first fault diagnosis unit 5. The control unit 30 also includes a first output unit 33 and a second output unit 34.

[0026] The drive control unit 31 is electrically connected to the first drive electrode 13. The drive control unit 31 outputs (applies) a drive signal D1 to the first drive electrode 13.

[0027] The carrier wave forming unit 32 is electrically connected to the first transport electrodes 14. The carrier wave forming unit 32 outputs (applies) a carrier wave signal H1 to the first transport electrodes 14.

[0028] The first angular velocity processing unit 4 includes a first connection circuit 41 , a second connection circuit 42 , a first addition circuit 43 , a first subtraction circuit 44 , and a first angular velocity calculation unit 45 .

[0029] The first connection circuit 41 is electrically connected to the first angular velocity detection electrode 11. The first connection circuit 41 is a CV (capacitance-voltage) conversion circuit that outputs a first detection signal V1 (voltage signal) according to the magnitude of the capacitance between the first angular velocity detection electrode 11 and the first vibrator 10.

[0030] The second connection circuit 42 is electrically connected to the second angular velocity detection electrode 12. The second connection circuit 42 is a CV (capacitance-voltage) conversion circuit that outputs a second detection signal V2 (voltage signal) according to the magnitude of the capacitance between the second angular velocity detection electrode 12 and the first vibrator 10.

[0031] The first adder circuit 43 generates a first sum signal A1, which is the sum of the first detection signal V1 and the second detection signal V2, by adding the first detection signal V1 output from the first connection circuit 41 and the second detection signal V2 output from the second connection circuit 42. The first adder circuit 43 outputs the first sum signal A1 to the first fault diagnosis unit 5.

[0032] The first subtraction circuit 44 generates a first differential signal S1, which is the difference, by calculating the difference between the first detection signal V1 output from the first connection circuit 41 and the second detection signal V2 output from the second connection circuit 42. The first subtraction circuit 44 outputs the first differential signal S1 to the first angular velocity calculation unit 45.

[0033] The first detection signal V1 includes a component of the carrier signal H1 and an angular velocity component (a component corresponding to the angular velocity applied to the first vibrator 10) superimposed on the carrier signal H1. The second detection signal V2 includes a component of the carrier signal H1 and a component in opposite phase to the angular velocity component.

[0034] Therefore, when the difference between the first detection signal V1 and the second detection signal V2 is calculated, the component of the carrier signal H1 is canceled out. In other words, the first differential signal S1 is a signal that does not include the component of the carrier signal H1 but includes an angular velocity component.

[0035] Furthermore, when the first detection signal V1 and the second detection signal V2 are added together, the angular velocity components are cancelled out. That is, the first addition signal A1 is a signal that does not include an angular velocity component but includes a component of the carrier signal H1.

[0036] The first fault diagnosis unit 5 determines whether there is a fault in the gyro sensor X1 based on the first sum signal A1. More specifically, the first fault diagnosis unit 5 determines whether there is a fault in the circuit extending from the first vibrator 10 to the first fault diagnosis unit 5 via the first angular velocity processing unit 4.

[0037] The first fault diagnosis unit 5 includes a first synchronous detection circuit 51 and a first smoothing filter (low-pass filter) 52. The first fault diagnosis unit 5 also includes a first diagnosis circuit 53.

[0038] The first synchronous detection circuit 51 detects (demodulates) the first sum signal A1 at the frequency of the carrier signal H1. The first smoothing filter 52 smoothes the output of the first synchronous detection circuit 51. The first diagnostic circuit 53 determines a failure of the gyro sensor X1 based on the output of the first smoothing filter 52.

[0039] The output of the first smoothing filter 52 is a DC signal whose magnitude corresponds to the gain of the circuit from the first vibrator 10 to the first smoothing filter 52. A state in which the gain of the above circuit is not an appropriate value corresponds to a failure of the gyro sensor X1, and is a state in which the accuracy of angular velocity detection by the gyro sensor X1 may decrease. The first diagnostic circuit 53 can determine a failure of the gyro sensor X1 by comparing the output of the first smoothing filter 52 with a threshold value.

[0040] For example, if there is a break in at least one of the electrical path between the first angular velocity detection electrode 11 and the first connection circuit 41 and the electrical path between the second angular velocity detection electrode 12 and the second connection circuit 42, the output of the first smoothing filter 52 will be smaller than that in a normal state. Therefore, the first diagnostic circuit 53 determines that a fault has occurred in the gyro sensor X1 when the output of the first smoothing filter 52 is smaller than the lower limit threshold.

[0041] Furthermore, if the gain is abnormal in at least a part of the circuit from the first vibrator 10 to the first smoothing filter 52, for example, the first connection circuit 41 or the second connection circuit 42, the output of the first smoothing filter 52 deviates from a normal value. Therefore, the first diagnostic circuit 53 determines that a failure has occurred in the gyro sensor X1 when the output of the first smoothing filter 52 is a value outside a predetermined range.

[0042] Furthermore, if impedance fluctuates in at least a portion of the circuit from the first vibrator 10 to the first synchronous detection circuit 51, causing a phase shift in the signal, the detection efficiency in the first synchronous detection circuit 51 will decrease and the output of the first smoothing filter 52 will be smaller than normal. Therefore, the first diagnostic circuit 53 determines that a fault has occurred in the gyro sensor X1 when the output of the first smoothing filter 52 is smaller than a predetermined threshold value.

[0043] The output of the first smoothing filter 52 is a DC signal whose magnitude corresponds to the capacitance between the first angular velocity detection electrode 11 and the first vibrator 10 and the capacitance between the second angular velocity detection electrode 12 and the first vibrator 10. The capacitance may not have an appropriate value if, for example, a foreign object is present between the first angular velocity detection electrode 11 and the first vibrator 10 or between the second angular velocity detection electrode 12 and the first vibrator 10. The inappropriate capacitance corresponds to a malfunction of the gyro sensor X1, which may reduce the accuracy of angular velocity detection by the gyro sensor X1. The first diagnostic circuit 53 can determine a malfunction of the gyro sensor X1 by comparing the output of the first smoothing filter 52 with a threshold value. For example, the first diagnostic circuit 53 determines that a malfunction has occurred in the gyro sensor X1 if the output of the first smoothing filter 52 is outside a predetermined range.

[0044] Next, the first angular velocity calculation unit 45 will be described. The first angular velocity calculation unit 45 generates a first angular velocity signal ω1 based on the first differential signal S1. The first angular velocity signal ω1 is a DC signal corresponding to the angular velocity applied to the first vibrator 10. The greater the angular velocity applied to the first vibrator 10, the greater the first angular velocity signal ω1.

[0045] The first angular velocity calculation unit 45 includes a second synchronous detection circuit 46, a third synchronous detection circuit 47, and a second smoothing filter 48 (low-pass filter).

[0046] The second synchronous detection circuit 46 detects (demodulates) the first differential signal S1 at the frequency of the carrier signal H1. The third synchronous detection circuit 47 detects the output of the second synchronous detection circuit 46 at the frequency of the drive signal D1. The second smoothing filter 48 smoothes the output of the third synchronous detection circuit 47. As a result, the second smoothing filter 48 generates the first angular velocity signal ω1.

[0047] The cutoff frequency of the first smoothing filter 52 of the first fault diagnosis unit 5 is higher than the cutoff frequency of the second smoothing filter 48 of the first angular velocity calculation unit 45. Therefore, the transient response of the first smoothing filter 52 is faster than the transient response of the second smoothing filter 48. As a result, if a fault occurs in the gyro sensor X1, the first fault diagnosis unit 5 can determine that the fault has occurred before the fault affects the first angular velocity signal ω1. For example, if the first fault diagnosis unit 5 determines that a fault has occurred in the gyro sensor X1, the first angular velocity signal ω1 can be invalidated in a device that operates based on the first angular velocity signal ω1, thereby preventing the device from malfunctioning.

[0048] The first diagnostic circuit 53 of the first fault diagnosis unit 5 outputs a first determination result signal R1 indicating the result of the fault diagnosis of the gyro sensor X1 to the first output unit 33. The first output unit 33 transmits the first determination result signal R1 to a device external to the gyro sensor X1. The first determination result signal R1 includes at least information indicating whether or not a fault has occurred.

[0049] The second output unit 34 transmits the first angular velocity signal ω1 output from the first angular velocity calculation unit 45 to a device external to the gyro sensor X1. Note that the first output unit 33 and the second output unit 34 may share at least a portion of their configuration.

[0050] (2) Second Embodiment A gyro sensor X2 according to a second embodiment will be described below with reference to Fig. 2. Components similar to those in the first embodiment will be denoted by the same reference numerals and will not be described again.

[0051] (2.1) Overview The gyro sensor X2 of embodiment 2 further includes a first monitor electrode 15, a second monitor electrode 16, a drive detection unit 6, a second fault diagnosis unit 7, and a third output unit 35 in addition to the configuration of the gyro sensor X1 of embodiment 1. The first monitor electrode 15 and the second monitor electrode 16 form the first angular velocity detection unit 1, and the drive detection unit 6, the second fault diagnosis unit 7, and the third output unit 35 form the control unit 30.

[0052] That is, the plurality of first electrodes further includes a first monitor electrode 15 and a second monitor electrode 16. The driving vibration of the first vibrator 10 changes the capacitance between the first monitor electrode 15 and the first vibrator 10. The driving vibration of the first vibrator 10 changes the capacitance between the second monitor electrode 16 and the first vibrator 10.

[0053] The control unit 30 further includes a drive detection unit 6 and a second fault diagnosis unit 7. The drive detection unit 6 generates a drive displacement signal Dp1 for correcting the drive signal D1.

[0054] More specifically, the drive detection unit 6 includes: a third connection circuit 61 electrically connected to the first monitor electrode 15 and outputting a signal corresponding to the capacitance between the first vibrator 10 and the first monitor electrode 15 as a first monitor signal M1; a fourth connection circuit 62 electrically connected to the second monitor electrode 16 and outputting a signal corresponding to the capacitance between the first vibrator 10 and the second monitor electrode 16 as a second monitor signal M2; a second subtraction circuit 64 outputting a second differential signal S2 which is the difference between the first monitor signal M1 and the second monitor signal M2; a second addition circuit 63 outputting a second addition signal A2 which is the sum of the first monitor signal M1 and the second monitor signal M2; and a correction calculation unit 65 which generates a drive displacement signal Dp1 based on the second differential signal S2 and outputs the drive displacement signal Dp1 to the drive control unit 31. The component included in the second monitor signal M2 and corresponding to the drive vibration of the first vibrator 10 is in opposite phase to the component included in the first monitor signal M1 and corresponding to the drive vibration of the first vibrator 10. The second fault diagnosis unit 7 determines a fault in the gyro sensor X2 based on the second addition signal A2, and outputs a second determination result signal R2.

[0055] Therefore, the drive detection unit 6 can correct the drive vibration of the first vibrator 10 using the drive displacement signal Dp1. Furthermore, the second fault diagnosis unit 7 can determine a fault in the circuit extending from the first vibrator 10 to the second fault diagnosis unit 7 via the drive detection unit 6 based on the second sum signal A2.

[0056] On the other hand, similar to the first embodiment, the first fault diagnosis unit 5 determines a fault in the circuit extending from the first vibrator 10 via the first angular velocity processing unit 4 to the first fault diagnosis unit 5. That is, according to the present embodiment, the first fault diagnosis unit 5 can determine a fault on the first angular velocity processing unit 4 side, and the second fault diagnosis unit 7 can determine a fault on the drive detection unit 6 side.

[0057] (2.2) Details The gyro sensor X2 of this embodiment will be described in more detail below.

[0058] The plurality of first electrodes include a first drive electrode 13 , a first angular velocity detection electrode 11 , a second angular velocity detection electrode 12 , a first transport electrode 14 , a first monitor electrode 15 , and a second monitor electrode 16 .

[0059] The plurality of first electrodes are arranged around the first vibrator 10 with a gap between them. Each of the plurality of first electrodes has a facing surface facing the first vibrator 10.

[0060] The first vibrator 10 is disposed between the first monitor electrode 15 and the second monitor electrode 16. The first monitor electrode 15 and the second monitor electrode 16 face the first vibrator 10 along the direction of the drive vibration of the first vibrator 10.

[0061] When the first vibrator 10 is driven to vibrate, the distance between the first vibrator 10 and the first monitor electrode 15 changes, and the capacitance between the first vibrator 10 and the first monitor electrode 15 changes. The third connection circuit 61 of the drive detection unit 6 outputs a first monitor signal M1 (voltage signal) according to the capacitance between the first vibrator 10 and the first monitor electrode 15.

[0062] When the first vibrator 10 is driven to vibrate, the distance between the first vibrator 10 and the second monitor electrode 16 changes, causing a change in the capacitance between the first vibrator 10 and the second monitor electrode 16. The fourth connection circuit 62 of the drive detection unit 6 outputs a second monitor signal M2 (voltage signal) according to the capacitance between the first vibrator 10 and the second monitor electrode 16.

[0063] The first monitor signal M1 and the second monitor signal M2 are signals obtained by amplitude-modulating the carrier signal H1 in accordance with the magnitude of the drive vibration of the first vibrator 10.

[0064] The drive detection unit 6 includes a third connection circuit 61 , a fourth connection circuit 62 , a second addition circuit 63 , a second subtraction circuit 64 , and a correction calculation unit 65 .

[0065] The third connection circuit 61 is electrically connected to the first monitor electrode 15. The third connection circuit 61 is a CV (capacitance-voltage) conversion circuit that outputs a first monitor signal M1 (voltage signal) according to the magnitude of the capacitance between the first monitor electrode 15 and the first vibrator 10.

[0066] The fourth connection circuit 62 is electrically connected to the second monitor electrode 16. The fourth connection circuit 62 is a CV (capacitance-voltage) conversion circuit that outputs a second monitor signal M2 (voltage signal) according to the magnitude of the capacitance between the second monitor electrode 16 and the first vibrator 10.

[0067] The second adder circuit 63 generates a second sum signal A2, which is the sum of the first monitor signal M1 and the second monitor signal M2, by adding the first monitor signal M1 output from the third connection circuit 61 and the second monitor signal M2 output from the fourth connection circuit 62. The second adder circuit 63 outputs the second sum signal A2 to the second fault diagnosis unit 7.

[0068] The second subtraction circuit 64 generates a second differential signal S2, which is the difference, by calculating the difference between the first monitor signal M1 output from the third connection circuit 61 and the second monitor signal M2 output from the fourth connection circuit 62. The second subtraction circuit 64 outputs the second differential signal S2 to the correction calculation unit 65.

[0069] The first monitor signal M1 includes a component of the carrier signal H1 and a drive displacement component (a component corresponding to the drive vibration of the first vibrator 10) superimposed on the carrier signal H1. The second monitor signal M2 includes a component of the carrier signal H1 and a component in opposite phase to the drive displacement component.

[0070] Therefore, when the difference between the first monitor signal M1 and the second monitor signal M2 is taken, the component of the carrier signal H1 is cancelled out. In other words, the second differential signal S2 is a signal that does not include the component of the carrier signal H1 but includes a drive displacement component.

[0071] Furthermore, when the first monitor signal M1 and the second monitor signal M2 are added together, the drive displacement component is cancelled out. That is, the second added signal A2 is a signal that does not include the drive displacement component but includes the component of the carrier signal H1.

[0072] The second fault diagnosis unit 7 determines a fault in the gyro sensor X2 based on the second addition signal A2. The second fault diagnosis unit 7 includes a fourth synchronous detection circuit 71 and a third smoothing filter 72. The second fault diagnosis unit 7 also includes a second diagnosis circuit 73.

[0073] The fourth synchronous detection circuit 71 detects (demodulates) the second sum signal A2 at the frequency of the carrier signal H1. The third smoothing filter 72 smoothes the output of the fourth synchronous detection circuit 71. The second diagnostic circuit 73 determines a failure of the gyro sensor X2 based on the output of the third smoothing filter 72.

[0074] The output of the third smoothing filter 72 is a DC signal whose magnitude corresponds to the gain of the circuit from the first vibrator 10 to the third smoothing filter 72. A state in which the gain of the above circuit is not an appropriate value corresponds to a failure of the gyro sensor X2, and is a state in which the accuracy of angular velocity detection by the gyro sensor X2 may decrease. The second diagnostic circuit 73 can determine a failure of the gyro sensor X2 by comparing the output of the third smoothing filter 72 with a threshold value.

[0075] For example, if there is a break in at least one of the electrical path between the first monitor electrode 15 and the third connecting circuit 61 and the electrical path between the second monitor electrode 16 and the fourth connecting circuit 62, the output of the third smoothing filter 72 will be smaller than that in a normal state. Therefore, the second diagnostic circuit 73 determines that a fault has occurred in the gyro sensor X2 when the output of the third smoothing filter 72 is smaller than the lower limit threshold.

[0076] Furthermore, if the gain is abnormal in at least a part of the circuit from the first vibrator 10 to the third smoothing filter 72, for example, the third connection circuit 61 or the fourth connection circuit 62, the output of the third smoothing filter 72 deviates from a normal value. Therefore, the second diagnostic circuit 73 determines that a failure has occurred in the gyro sensor X2 when the output of the third smoothing filter 72 is a value outside a predetermined range.

[0077] Furthermore, if impedance fluctuates in at least a portion of the circuit from the first vibrator 10 to the fourth synchronous detection circuit 71, causing a phase shift in the signal, the detection efficiency in the fourth synchronous detection circuit 71 will decrease, and the output of the third smoothing filter 72 will become smaller than normal. Therefore, the second diagnostic circuit 73 determines that a fault has occurred in the gyro sensor X2 when the output of the third smoothing filter 72 is smaller than a predetermined threshold value.

[0078] The output of the third smoothing filter 72 is a DC signal whose magnitude corresponds to the capacitance between the first monitor electrode 15 and the first vibrator 10 and the capacitance between the second monitor electrode 16 and the first vibrator 10. The capacitance may not have an appropriate value if, for example, a foreign object is present between the first monitor electrode 15 and the first vibrator 10 or between the second monitor electrode 16 and the first vibrator 10. The inappropriate capacitance corresponds to a malfunction of the gyro sensor X2, which may reduce the accuracy of angular velocity detection by the gyro sensor X2. The second diagnostic circuit 73 can determine a malfunction of the gyro sensor X2 by comparing the output of the third smoothing filter 72 with a threshold value. For example, the second diagnostic circuit 73 determines that a malfunction has occurred in the gyro sensor X2 if the output of the third smoothing filter 72 is outside a predetermined range.

[0079] The second diagnostic circuit 73 outputs a second determination result signal R2 indicating the result of the fault diagnosis of the gyro sensor X2 to the third output unit 35. The third output unit 35 transmits the second determination result signal R2 to a device external to the gyro sensor X2. The second determination result signal R2 includes at least information indicating whether or not a fault has occurred.

[0080] Two or three of the first output section 33, the second output section 34, and the third output section 35 may share at least a portion of the configuration.

[0081] Next, the correction calculation unit 65 will be described. The correction calculation unit 65 generates a drive displacement signal Dp1 based on the second differential signal S2 and outputs the drive displacement signal Dp1 to the drive control unit 31. The drive control unit 31 corrects the drive signal D1 based on the drive displacement signal Dp1. That is, the drive control unit 31 generates the drive signal D1 by feeding back the first monitor signal M1 and the second monitor signal M2. The correction calculation unit 65 generates the drive displacement signal Dp1 so that the amplitudes of the first monitor signal M1 and the second monitor signal M2 are between a predetermined upper limit and a predetermined lower limit.

[0082] (3) Third Embodiment A gyro sensor X3 according to a third embodiment will be described below with reference to Fig. 3. The same components as those in the first or second embodiment will be denoted by the same reference numerals and will not be described again.

[0083] The gyro sensor X3 of the third embodiment further includes a first monitor electrode 15, a second monitor electrode 16, a drive detection unit 6, and a first post-stage adding circuit 36 ​​in addition to the configuration of the gyro sensor X1 of the first embodiment.

[0084] The configurations and functions of the first monitor electrode 15, the second monitor electrode 16, and the drive detection unit 6 of the gyro sensor X3 of embodiment 3 are the same as those of embodiment 2. In the gyro sensor X3 of embodiment 3, the first fault diagnosis unit 5 performs the function of the second fault diagnosis unit 7 of the gyro sensor X2 of embodiment 2. This will be described in more detail below.

[0085] The plurality of first electrodes include a first monitor electrode 15 and a second monitor electrode 16. The driving vibration of the first vibrator 10 changes the capacitance between the first monitor electrode 15 and the first vibrator 10. The driving vibration of the first vibrator 10 changes the capacitance between the second monitor electrode 16 and the first vibrator 10.

[0086] The control unit 30 has a drive detection unit 6 and a first post-stage adding circuit 36. The drive detection unit 6 generates a drive displacement signal Dp1 for correcting the drive signal D1.

[0087] More specifically, the drive detection unit 6 includes: a third connection circuit 61 electrically connected to the first monitor electrode 15 and outputting a signal corresponding to the capacitance between the first vibrator 10 and the first monitor electrode 15 as a first monitor signal M1; a fourth connection circuit 62 electrically connected to the second monitor electrode 16 and outputting a signal corresponding to the capacitance between the first vibrator 10 and the second monitor electrode 16 as a second monitor signal M2; a second subtraction circuit 64 outputting a second differential signal S2 which is the difference between the first monitor signal M1 and the second monitor signal M2; a second addition circuit 63 outputting a second addition signal A2 which is the sum of the first monitor signal M1 and the second monitor signal M2; and a correction calculation unit 65 which generates a drive displacement signal Dp1 based on the second differential signal S2 and outputs the drive displacement signal Dp1 to the drive control unit 31. The component of the second monitor signal M2 corresponding to the drive vibration of the first vibrator 10 is in opposite phase to the component of the first monitor signal M1 corresponding to the drive vibration of the first vibrator 10. The first post-stage adder circuit 36 ​​outputs a fourth sum signal A12 which is the sum of the first sum signal A1 and the second sum signal A2. The first fault diagnosis unit 5 determines a fault in the gyro sensor X3 based on the fourth sum signal A12 which is the sum of the first sum signal A1 and the second sum signal A2, and outputs a first determination result signal R1.

[0088] As in the first and second embodiments, the first diagnostic circuit 53 of the first fault diagnosis unit 5 can determine a fault in the gyro sensor X3 by comparing the output of the first smoothing filter 52 with a threshold value.

[0089] The first diagnostic circuit 53 determines that a malfunction has occurred in the gyro sensor X3 when, for example, the output of the first smoothing filter 52 is a value outside a predetermined range. Also, the first diagnostic circuit 53 determines that a malfunction has occurred in the gyro sensor X3 when, for example, the output of the first smoothing filter 52 is smaller than a predetermined threshold value.

[0090] According to this embodiment, the first fault diagnosis unit 5 can determine whether there is a fault in both the first angular velocity processing unit 4 and the drive detection unit 6. Therefore, compared to the case where the second fault diagnosis unit 7 is provided as in the second embodiment, the circuit area can be reduced.

[0091] (4) Fourth Embodiment A gyro sensor X4 according to a fourth embodiment will be described below with reference to Fig. 4. Components similar to those in the first embodiment will be given the same reference numerals and will not be described again.

[0092] (4.1) Overview The gyro sensor X4 of embodiment 4 further includes a second angular velocity detection unit 2, a second angular velocity processing unit 8, a second post-stage adder circuit 37, and a fourth output unit 38 in addition to the configuration of the gyro sensor X1 of embodiment 1. The second angular velocity processing unit 8, the second post-stage adder circuit 37, and the fourth output unit 38 are components of the control unit 30.

[0093] The angular velocity detection direction of the second angular velocity detection unit 2 is different from the angular velocity detection direction of the first angular velocity detection unit 1. For example, the first angular velocity detection unit 1 detects angular velocity around the X-axis, and the second angular velocity detection unit 2 detects angular velocity around an axis (Y-axis or Z-axis) perpendicular to the X-axis.

[0094] The second angular velocity detection unit 2 has a second vibrator 20 and a plurality of second electrodes. The plurality of second electrodes are arranged to face the second vibrator 20, and form a capacitance between the second vibrator 20 and the second electrodes.

[0095] The plurality of second electrodes include a second drive electrode 23 to which a drive signal D1 for driving and vibrating the second vibrator 20 is applied from the drive control unit 31, a third angular velocity detection electrode 21 in which the capacitance between the second vibrator 20 and the third angular velocity detection electrode 21 changes due to the detection vibration of the second vibrator 20 caused by the application of an angular velocity to the second vibrator 20, a fourth angular velocity detection electrode 22 in which the capacitance between the second vibrator 20 and the fourth angular velocity detection electrode 22 changes due to the detection vibration of the second vibrator 20 caused by the application of an angular velocity to the second vibrator 20, and a second transport electrode 24 to which a carrier wave signal H1 is applied from the carrier wave forming unit 32.

[0096] The control unit 30 includes a second angular velocity processing unit 8 that generates a second angular velocity signal ω2 corresponding to the angular velocity applied to the second vibrator 20, and a second post-stage adding circuit 37.

[0097] The second angular velocity processing unit 8 includes: a fifth connection circuit 81 electrically connected to the third angular velocity detection electrode 21 and outputting a signal corresponding to the capacitance between the second vibrator 20 and the third angular velocity detection electrode 21 as a third detection signal V3; a sixth connection circuit 82 electrically connected to the fourth angular velocity detection electrode 22 and outputting a signal corresponding to the capacitance between the second vibrator 20 and the fourth angular velocity detection electrode 22 as a fourth detection signal V4; a third subtraction circuit 84 outputting a third differential signal S3 which is the difference between the third detection signal V3 and the fourth detection signal V4; a third addition circuit 83 outputting a third addition signal A3 which is the sum of the third detection signal V3 and the fourth detection signal V4; and a second angular velocity calculation unit 85 which generates a second angular velocity signal ω2 based on the third differential signal S3.

[0098] The component of the fourth detection signal V4 corresponding to the angular velocity applied to the second vibrator 20 is in opposite phase to the component of the third detection signal V3 corresponding to the angular velocity applied to the second vibrator 20.

[0099] The second post-stage adder circuit 37 outputs a fifth sum signal A13 which is the sum of the first sum signal A1 and the third sum signal A3.

[0100] The first fault diagnosis unit 5 determines whether or not the gyro sensor X4 has a fault based on a fifth sum signal A13, which is the sum of the first sum signal A1 and the third sum signal A3, and outputs a first determination result signal R1.

[0101] According to the above configuration, first fault diagnosis unit 5 can determine a fault in the circuit extending from first vibrator 10 via first angular velocity processing unit 4 to first fault diagnosis unit 5, and a fault in the circuit extending from second vibrator 20 via second angular velocity processing unit 8 to first fault diagnosis unit 5. In other words, first fault diagnosis unit 5 can determine a fault on the side of first angular velocity processing unit 4 and a fault on the side of second angular velocity processing unit 8. Therefore, the circuit area can be reduced compared to when a circuit for determining a fault on the side of second angular velocity processing unit 8 is provided separately from first fault diagnosis unit 5.

[0102] (4.2) Details The gyro sensor X4 of this embodiment will be described in more detail below.

[0103] The second vibrator 20, the third angular velocity detection electrode 21, the fourth angular velocity detection electrode 22, the second drive electrode 23, and the second transport electrode 24 of the second angular velocity detection unit 2 have the same configurations as the first vibrator 10, the first angular velocity detection electrode 11, the second angular velocity detection electrode 12, the first drive electrode 13, and the first transport electrode 14 of the first angular velocity detection unit 1, respectively. Therefore, a detailed description of the second angular velocity detection unit 2 will be omitted.

[0104] The second angular velocity calculation unit 85 includes a fifth synchronous detection circuit 86, a sixth synchronous detection circuit 87, and a fourth smoothing filter 88. The fifth synchronous detection circuit 86, the sixth synchronous detection circuit 87, and the fourth smoothing filter 88 have the same configurations as the second synchronous detection circuit 46, the third synchronous detection circuit 47, and the second smoothing filter 48 of the first angular velocity calculation unit 45, respectively. Therefore, a detailed description of the second angular velocity calculation unit 85 will be omitted.

[0105] The fifth connection circuit 81, the sixth connection circuit 82, the third addition circuit 83, the third subtraction circuit 84, and the second angular velocity calculation unit 85 of the second angular velocity processing unit 8 have the same configurations as the first connection circuit 41, the second connection circuit 42, the first addition circuit 43, the first subtraction circuit 44, and the first angular velocity calculation unit 45 of the first angular velocity processing unit 4. Therefore, a detailed description of the second angular velocity processing unit 8 will be omitted.

[0106] The fourth output unit 38 transmits the second angular velocity signal ω2 output from the second angular velocity calculation unit 85 to a device external to the gyro sensor X4.

[0107] Two or three of the first output section 33, the second output section 34, and the fourth output section 38 may share at least a portion of the configuration.

[0108] (5) Modification of Embodiment 4 The gyro sensor X4 of Embodiment 4 includes two angular velocity detection units (a first angular velocity detection unit 1 and a second angular velocity detection unit 2) and two angular velocity processing units (a first angular velocity processing unit 4 and a second angular velocity processing unit 8) that correspond one-to-one to the two angular velocity detection units.

[0109] The gyro sensor X4 may include three or more angular velocity detection units and three or more angular velocity processing units that correspond one-to-one to the three or more angular velocity detection units. In this case, the first fault diagnosis unit 5 may determine a fault in the gyro sensor X4 based on the sum of the addition signals output from the three or more angular velocity processing units.

[0110] Furthermore, the fourth embodiment may be realized in combination with the second or third embodiment. For example, each of the multiple (e.g., two) angular velocity detection units of the gyro sensor X4 of the fourth embodiment may have two monitor electrodes, similar to the first angular velocity detection unit 1 of the second or third embodiment. Furthermore, the control unit 30 of the gyro sensor X4 of the fourth embodiment may have multiple (e.g., two) drive detection units 6 connected to the multiple (e.g., two) angular velocity detection units, respectively.

[0111] In addition, the first fault diagnosis unit 5 may determine a fault in the gyro sensor X4 based on a signal obtained by adding together at least one sum signal output from at least one of the plurality of angular velocity processing units and at least one sum signal output from at least one of the plurality of drive detection units 6.

[0112] (6) Modifications of Embodiments 1 to 4 Modifications of Embodiments 1 to 4 are listed below. The following modifications may be implemented in appropriate combination. Furthermore, the following modifications may be implemented in appropriate combination with the modifications described above.

[0113] The above-described fault diagnosis processes in the first fault diagnosis unit 5 and the second fault diagnosis unit 7 are merely examples and can be modified as appropriate. In addition, the first fault diagnosis unit 5 and the second fault diagnosis unit 7 may use a trained model for fault diagnosis.

[0114] The multiple components of each of the gyro sensors X1 to X4 may be integrated into one housing, or may be distributed across multiple housings. For example, the multiple components of the control unit 30 may be distributed across multiple housings.

[0115] (7) Summary The above-described embodiments and the like disclose the following aspects.

[0116] A gyro sensor (X1 to X4) according to a first aspect includes a first angular velocity detection unit (1) and a control unit (30). The first angular velocity detection unit (1) has a first vibrator (10) and a plurality of first electrodes. The plurality of first electrodes are arranged to face the first vibrator (10) and form a capacitance between the first vibrator (10) and the control unit (30). The control unit (30) is electrically connected to the plurality of first electrodes. The plurality of first electrodes include a first drive electrode (13) to which a drive signal (D1) for driving and vibrating the first vibrator (10) is applied, a first angular velocity detection electrode (11) in which the capacitance between the first vibrator (10) and the first drive electrode (13) changes due to the detection vibration of the first vibrator (10) caused by the application of an angular velocity to the first vibrator (10), a second angular velocity detection electrode (12) in which the capacitance between the first vibrator (10) and the first drive electrode (13) changes due to the detection vibration of the first vibrator (10) caused by the application of an angular velocity to the first vibrator (10), and a first transport electrode (14) to which a carrier signal (H1) is applied. The control unit (30) has a drive control unit (31) that applies a drive signal (D1) to the first drive electrode (13), a carrier wave forming unit (32) that applies a carrier signal (H1) to the first carrier electrode (14), a first angular velocity processing unit (4) that generates a first angular velocity signal (ω1) corresponding to the angular velocity applied to the first vibrator (10), and a first fault diagnosis unit (5). The frequency of the carrier signal (H1) is higher than the frequency of the drive signal (D1).The first angular velocity processing unit (4) is electrically connected to the first angular velocity detection electrode (11) and outputs a signal corresponding to the capacitance between the first vibrator (10) and the first angular velocity detection electrode (11) as a first detection signal (V1), and is electrically connected to the second angular velocity detection electrode (12) and outputs a signal corresponding to the capacitance between the first vibrator (10) and the second angular velocity detection electrode (12) as a second detection signal (V2). The gyro sensor (10) includes a second connection circuit (42) that outputs a first differential signal (S1) that is the difference between the first detection signal (V1) and the second detection signal (V2), a first subtraction circuit (44) that outputs a first differential signal (S1) that is the difference between the first detection signal (V1) and the second detection signal (V2), a first summation circuit (43) that outputs a first summation signal (A1) that is the sum of the first detection signal (V1) and the second detection signal (V2), and a first angular velocity calculation unit (45) that generates a first angular velocity signal (ω1) based on the first differential signal (S1). A component included in the second detection signal (V2) that corresponds to the angular velocity applied to the first vibrator (10) is in opposite phase to a component included in the first detection signal (V1) that corresponds to the angular velocity applied to the first vibrator (10). A first fault diagnosis unit (5) determines a fault in the gyro sensor (X1 to X4) based on the first summation signal (A1) and outputs a first determination result signal (R1).

[0117] The above configuration enables fault diagnosis without using a test signal. Therefore, the circuit for generating the test signal can be omitted, reducing the circuit area of ​​the gyro sensors (X1 to X4). Furthermore, circuit noise can be reduced compared to when a test signal is applied to the circuit.

[0118] In the gyro sensor (X2) according to the second aspect, in the first aspect, the plurality of first electrodes further include a first monitor electrode (15) whose capacitance with the first vibrator (10) changes due to the driving vibration of the first vibrator (10), and a second monitor electrode (16) whose capacitance with the first vibrator (10) changes due to the driving vibration of the first vibrator (10). The control unit (30) further includes a drive detection unit (6) that generates a drive displacement signal (Dp1) for correcting the drive signal (D1), and a second fault diagnosis unit (7). The drive detection unit (6) includes a third connection circuit (61) electrically connected to the first monitor electrode (15) and outputting a signal corresponding to the capacitance between the first vibrator (10) and the first monitor electrode (15) as a first monitor signal (M1), and a fourth connection circuit (62) electrically connected to the second monitor electrode (16) and outputting a signal corresponding to the capacitance between the first vibrator (10) and the second monitor electrode (16) as a second monitor signal (M2). The gyro sensor (X2) includes a first monitor signal (M1) and a second monitor signal (M2), a second subtraction circuit (64) that outputs a second differential signal (S2) that is the difference between the first monitor signal (M1) and the second monitor signal (M2), a second addition circuit (63) that outputs a second sum signal (A2) that is the sum of the first monitor signal (M1) and the second monitor signal (M2), and a correction calculation unit (65) that generates a drive displacement signal (Dp1) based on the second differential signal (S2) and outputs the drive displacement signal (Dp1) to a drive control unit (31). A component corresponding to the drive vibration of the first vibrator (10) contained in the second monitor signal (M2) is in opposite phase to a component corresponding to the drive vibration of the first vibrator (10) contained in the first monitor signal (M1). A second fault diagnosis unit (7) determines a fault in the gyro sensor (X2) based on the second sum signal (A2) and outputs a second determination result signal (R2).

[0119] According to the above configuration, the second fault diagnosis unit (7) can determine a fault in the circuit extending from the first vibrator (10) via the drive detection unit (6) to the second fault diagnosis unit (7) based on the second sum signal (A2).

[0120] In addition, in the gyro sensor (X3) according to the third aspect, in the first aspect, the plurality of first electrodes further include a first monitor electrode (15) whose capacitance with the first vibrator (10) changes due to the driving vibration of the first vibrator (10), and a second monitor electrode (16) whose capacitance with the first vibrator (10) changes due to the driving vibration of the first vibrator (10). The control unit (30) further includes a drive detection unit (6) that generates a drive displacement signal (Dp1) for correcting the drive signal (D1), and a first post-stage adder circuit (36). The drive detection unit (6) includes a third connection circuit (61) electrically connected to the first monitor electrode (15) and outputting a signal corresponding to the capacitance between the first vibrator (10) and the first monitor electrode (15) as a first monitor signal (M1), and a fourth connection circuit (62) electrically connected to the second monitor electrode (16) and outputting a signal corresponding to the capacitance between the first vibrator (10) and the second monitor electrode (16) as a second monitor signal (M2). The monitor circuit (31) includes a first monitor signal (M1) and a second monitor signal (M2), a second subtraction circuit (64) that outputs a second differential signal (S2) that is the difference between the first monitor signal (M1) and the second monitor signal (M2), a second adder circuit (63) that outputs a second sum signal (A2) that is the sum of the first monitor signal (M1) and the second monitor signal (M2), and a correction calculation unit (65) that generates a drive displacement signal (Dp1) based on the second differential signal (S2) and outputs the drive displacement signal (Dp1) to a drive control unit (31). A component included in the second monitor signal (M2) that corresponds to the drive vibration of the first vibrator (10) is in opposite phase to a component included in the first monitor signal (M1) that corresponds to the drive vibration of the first vibrator (10). The first post-stage adder circuit (36) outputs a sum signal (A12) that is the sum of the first sum signal (A1) and the second sum signal (A2). The first fault diagnosis unit (5) determines a fault in the gyro sensor (X3) based on an addition signal (A12) which is the sum of the first addition signal (A1) and the second addition signal (A2), and outputs a first determination result signal (R1).

[0121] According to the above configuration, the first fault diagnosis unit (5) can distinguish between a fault on the first angular velocity processing unit (4) side and a fault on the second angular velocity processing unit (8) side. Therefore, the circuit area can be reduced compared to when a circuit for determining a fault on the second angular velocity processing unit (8) side is provided separately from the first fault diagnosis unit (5).

[0122] Furthermore, the gyro sensor (X4) according to a fourth aspect is any one of the first to third aspects, and further includes a second angular velocity detection unit (2) that detects angular velocity in a direction different from that of the first angular velocity detection unit (1). The second angular velocity detection unit (2) has a second vibrator (20) and a plurality of second electrodes that are arranged to face the second vibrator (20) and form a capacitance between the second vibrator (20) and the second vibrator (20). The plurality of second electrodes include a second driving electrode (23) to which a driving signal (D1) for driving and vibrating the second vibrator (20) is applied from a driving control unit (31), a third angular velocity detection electrode (21) in which the capacitance between the second vibrator (20) and the third angular velocity detection electrode (21) changes due to the detection vibration of the second vibrator (20) caused by the application of an angular velocity to the second vibrator (20), a fourth angular velocity detection electrode (22) in which the capacitance between the second vibrator (20) and the fourth angular velocity detection electrode (22) changes due to the detection vibration of the second vibrator (20) caused by the application of an angular velocity to the second vibrator (20), and a second transport electrode (24) to which a carrier wave signal (H1) is applied from a carrier wave forming unit (32). The control unit (30) further includes a second angular velocity processing unit (8) that generates a second angular velocity signal (ω2) corresponding to the angular velocity applied to the second vibrator (20), and a second post-stage adding circuit (37). The second angular velocity processing unit (8) includes a fifth connection circuit (81) that is electrically connected to the third angular velocity detection electrode (21) and outputs a signal corresponding to the capacitance between the second vibrator (20) and the third angular velocity detection electrode (21) as a third detection signal (V3), and a fourth connection circuit (81) that is electrically connected to the fourth angular velocity detection electrode (22) and outputs a signal corresponding to the capacitance between the second vibrator (20) and the fourth angular velocity detection electrode (22) as a fourth detection signal (V4). a third subtraction circuit (84) that outputs a third differential signal (S3) that is the difference between the third detection signal (V3) and the fourth detection signal (V4); a third addition circuit (83) that outputs a third addition signal (A3) that is the sum of the third detection signal (V3) and the fourth detection signal (V4); and a second angular velocity calculation unit (85) that generates a second angular velocity signal (ω2) based on the third differential signal (S3).A component included in the fourth detection signal (V4) and corresponding to the angular velocity applied to the second vibrator (20) is in opposite phase to a component included in the third detection signal (V3) and corresponding to the angular velocity applied to the second vibrator (20). The second post-stage adder circuit (37) outputs an added signal (A13) which is the sum of the first added signal (A1) and the third added signal (A3). The first fault diagnosis unit (5) determines a fault in the gyro sensor (X4) based on the added signal (A13) which is the sum of the first added signal (A1) and the third added signal (A3), and outputs a first determination result signal (R1).

[0123] According to the above configuration, the first fault diagnosis unit (5) can distinguish between a fault on the first angular velocity processing unit (4) side and a fault on the second angular velocity processing unit (8) side. Therefore, the circuit area can be reduced compared to when a circuit for determining a fault on the second angular velocity processing unit (8) side is provided separately from the first fault diagnosis unit (5).

[0124] In addition, in the gyro sensor (X1 to X4) according to the fifth aspect, in any one of the first to fourth aspects, the first fault diagnosis unit (5) includes a first synchronous detection circuit (51) that detects the first sum signal (A1) at the frequency of the carrier signal (H1), and a first smoothing filter (52) that smoothes the output of the first synchronous detection circuit (51).

[0125] According to the above configuration, the first sum signal (A1) can be converted into a signal suitable for fault diagnosis.

[0126] In addition, in the gyro sensor (X1 to X4) according to a sixth aspect, in the fifth aspect, the first angular velocity calculation unit (45) includes a second synchronous detection circuit (46) that detects the first differential signal (S1) at the frequency of the carrier signal (H1), a third synchronous detection circuit (47) that detects the output of the second synchronous detection circuit (46) at the frequency of the drive signal (D1), and a second smoothing filter (48) that smoothes the output of the third synchronous detection circuit (47). The cutoff frequency of the first smoothing filter (52) is higher than the cutoff frequency of the second smoothing filter (48).

[0127] According to the above configuration, the transient response of the first smoothing filter (52) is faster than the transient response of the second smoothing filter (48). As a result, when a fault occurs in the gyro sensor (X1 to X4), the first fault diagnosis unit (5) can determine that the fault has occurred before the fault affects the first angular velocity signal (ω1).

[0128] The configurations other than those of the first aspect are not essential for the gyro sensors (X1 to X4) and can be omitted as appropriate.

[0129] 1 First angular velocity detection unit 2 Second angular velocity detection unit 4 First angular velocity processing unit 5 First fault diagnosis unit 6 Drive detection unit 7 Second fault diagnosis unit 8 Second angular velocity processing unit 10 First vibrator 11 First angular velocity detection electrode 12 Second angular velocity detection electrode 13 First drive electrode 14 First transport electrode 15 First monitor electrode 16 Second monitor electrode 20 Second vibrator 21 Third angular velocity detection electrode 22 Fourth angular velocity detection electrode 23 Second drive electrode 24 Second transport electrode 30 Control unit 31 Drive control unit 32 Carrier wave formation unit 36 ​​First post-stage adder circuit 37 Second post-stage adder circuit 41 First connection circuit 42 Second connection circuit 43 First adder circuit 44 First subtraction circuit 45 First angular velocity calculation unit 46 Second synchronous detection circuit 47 Third synchronous detection circuit 48 Second smoothing filter 51 First synchronous detection circuit 52 First smoothing filter 61 Third connection circuit 62 Fourth connection circuit 63 Second addition circuit 64 Second subtraction circuit 65 Correction calculation unit 81 Fifth connection circuit 82 Sixth connection circuit 83 Third addition circuit 84 Third subtraction circuit 85 Second angular velocity calculation unit A1 First sum signal A2 Second sum signal A3 Third sum signal A12 Summation signal A13 Summation signal D1 Drive signal Dp1 Drive displacement signal H1 Carrier signal M1 First monitor signal M2 Second monitor signal R1 First determination result signal R2 Second determination result signal S1 First differential signal S2 Second differential signal S3 Third differential signal V1 First detection signal V2: Second detection signal V3: Third detection signal V4: Fourth detection signal X1 to X4: Gyro sensor ω1: First angular velocity signal ω2: Second angular velocity signal

Claims

1. A gyro sensor comprising: a first angular velocity detection unit having a first vibrator; and a plurality of first electrodes arranged to face the first vibrator and forming capacitance between the first vibrator and the first vibrator; and a control unit electrically connected to the plurality of first electrodes, wherein the plurality of first electrodes include: a first drive electrode to which a drive signal for driving the first vibrator is applied; a first angular velocity detection electrode whose capacitance with the first vibrator changes due to detected vibration of the first vibrator caused by application of an angular velocity to the first vibrator; a second angular velocity detection electrode whose capacitance with the first vibrator changes due to the detected vibration of the first vibrator caused by application of the angular velocity to the first vibrator; and a first transport electrode to which a carrier wave signal is applied, wherein the control unit comprises: a drive control unit that applies the drive signal to the first drive electrode; and a carrier wave formation unit that applies the carrier wave signal to the first transport electrode. the first angular velocity processing unit includes a first angular velocity processing section that generates a first angular velocity signal corresponding to the angular velocity applied to the first vibrator; and a first fault diagnosis section, wherein the frequency of the carrier signal is higher than the frequency of the drive signal, and the first angular velocity processing section includes: a first connection circuit that is electrically connected to the first angular velocity detection electrode and that outputs a signal corresponding to a capacitance between the first vibrator and the first angular velocity detection electrode as a first detection signal; a second connection circuit that is electrically connected to the second angular velocity detection electrode and that outputs a signal corresponding to a capacitance between the first vibrator and the second angular velocity detection electrode as a second detection signal; a first subtraction circuit that outputs a first differential signal that is a difference between the first detection signal and the second detection signal; a first addition circuit that outputs a first addition signal that is a sum of the first detection signal and the second detection signal; and a first angular velocity calculation section that generates the first angular velocity signal based on the first differential signal, a component included in the second detection signal and corresponding to the angular velocity applied to the first vibrator has an opposite phase to a component included in the first detection signal and corresponding to the angular velocity applied to the first vibrator;The first failure diagnosis unit determines a failure of the gyro sensor based on the first addition signal, and outputs a first determination result signal.

2. The plurality of first electrodes further include: a first monitor electrode whose capacitance with the first vibrator changes due to the drive vibration of the first vibrator; and a second monitor electrode whose capacitance with the first vibrator changes due to the drive vibration of the first vibrator; and the control unit further has: a drive detection unit that generates a drive displacement signal for correcting the drive signal; and a second fault diagnosis unit; and the drive detection unit further includes: a third connection circuit that is electrically connected to the first monitor electrode and outputs a signal corresponding to the capacitance between the first vibrator and the first monitor electrode as a first monitor signal; a fourth connection circuit that is electrically connected to the second monitor electrode and outputs a signal corresponding to the capacitance between the first vibrator and the second monitor electrode as a second monitor signal; and a second subtraction circuit that outputs a second differential signal that is the difference between the first monitor signal and the second monitor signal.

2. The gyro sensor according to claim 1, comprising: a second adder circuit that outputs a second sum signal that is the sum of the first monitor signal and the second monitor signal; and a correction calculation unit that generates the drive displacement signal based on the second differential signal and outputs the drive displacement signal to the drive control unit, wherein a component of the second monitor signal that corresponds to the drive vibration of the first vibrator is in opposite phase to a component of the first monitor signal that corresponds to the drive vibration of the first vibrator, and the second fault diagnosis unit determines a fault in the gyro sensor based on the second sum signal and outputs a second determination result signal.

3. The plurality of first electrodes further include: a first monitor electrode whose capacitance with the first vibrator changes due to the driving vibration of the first vibrator; and a second monitor electrode whose capacitance with the first vibrator changes due to the driving vibration of the first vibrator; and the control unit further has: a drive detection unit that generates a drive displacement signal for correcting the drive signal; and a first post-stage adder circuit; and the drive detection unit further has: a third connection circuit that is electrically connected to the first monitor electrode and outputs a signal corresponding to the capacitance between the first vibrator and the first monitor electrode as a first monitor signal; a fourth connection circuit that is electrically connected to the second monitor electrode and outputs a signal corresponding to the capacitance between the first vibrator and the second monitor electrode as a second monitor signal; and a second subtraction circuit that outputs a second differential signal that is the difference between the first monitor signal and the second monitor signal.

2. The gyro sensor according to claim 1, comprising: a second adder circuit that outputs a second sum signal that is the sum of the first monitor signal and the second monitor signal; and a correction calculation unit that generates the drive displacement signal based on the second differential signal and outputs the drive displacement signal to the drive control unit, wherein a component of the second monitor signal that corresponds to the drive vibration of the first vibrator is in opposite phase to a component of the first monitor signal that corresponds to the drive vibration of the first vibrator, the first post-adder circuit outputs a fourth sum signal that is the sum of the first sum signal and the second sum signal, and the first fault diagnosis unit determines a fault in the gyro sensor based on the fourth sum signal and outputs the first determination result signal.

4. The device further comprises a second angular velocity detection unit having a different angular velocity detection direction from that of the first angular velocity detection unit, wherein the second angular velocity detection unit has: a second vibrator; and a plurality of second electrodes arranged to face the second vibrator and forming capacitance between the second vibrator and the second vibrator, wherein the plurality of second electrodes include: a second drive electrode to which the drive signal for driving the second vibrator to vibrate is applied from the drive control unit; a third angular velocity detection electrode whose capacitance with the second vibrator changes due to the detection vibration of the second vibrator caused by the application of an angular velocity to the second vibrator; a fourth angular velocity detection electrode whose capacitance with the second vibrator changes due to the detection vibration of the second vibrator caused by the application of the angular velocity to the second vibrator; and a second carrier electrode to which the carrier wave signal is applied from the carrier wave generation unit, wherein the control unit the second angular velocity processing unit further comprises: a second angular velocity processing unit that generates a second angular velocity signal corresponding to the angular velocity applied to the second vibrator; and a second post-stage adder circuit, wherein the second angular velocity processing unit comprises: a fifth connection circuit that is electrically connected to the third angular velocity detection electrode and that outputs a signal corresponding to the capacitance between the second vibrator and the third angular velocity detection electrode as a third detection signal; a sixth connection circuit that is electrically connected to the fourth angular velocity detection electrode and that outputs a signal corresponding to the capacitance between the second vibrator and the fourth angular velocity detection electrode as a fourth detection signal; a third subtraction circuit that outputs a third differential signal that is the difference between the third detection signal and the fourth detection signal; a third adder circuit that outputs a third summation signal that is the sum of the third detection signal and the fourth detection signal; and a second angular velocity calculation unit that generates the second angular velocity signal based on the third differential signal, a component included in the fourth detection signal and corresponding to the angular velocity applied to the second vibrator is in antiphase with a component included in the third detection signal and corresponding to the angular velocity applied to the second vibrator, the second post-stage adder circuit outputs a fifth sum signal that is the sum of the first sum signal and the third sum signal,The gyro sensor according to claim 1 , wherein the first failure diagnosis unit determines a failure of the gyro sensor based on the fifth addition signal, and outputs the first determination result signal.

5. A gyro sensor as described in claim 1, wherein the first fault diagnosis unit comprises: a first synchronous detection circuit that detects the first summed signal at the frequency of the carrier signal; and a first smoothing filter that smooths the output of the first synchronous detection circuit.

6. A gyro sensor as described in claim 5, wherein the first angular velocity calculation unit comprises: a second synchronous detection circuit that detects the first differential signal at the frequency of the carrier signal; a third synchronous detection circuit that detects the output of the second synchronous detection circuit at the frequency of the drive signal; and a second smoothing filter that smooths the output of the third synchronous detection circuit, and the cutoff frequency of the first smoothing filter is higher than the cutoff frequency of the second smoothing filter.

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