Gyro sensor

Abstract

To improve accuracy of fault diagnosis using test signals.SOLUTION: A gyro sensor 1 comprises a transducer 10, a plurality of electrodes 2, and a control unit U1. The control unit U1 comprises a drive circuit 31, a conversion circuit 41, a first demodulation circuit 42, a detection processing circuit 33, a second demodulation circuit 51, a quadrature feedback circuit 53, a test signal generator 34, and a plurality of diagnosis circuits 6. The plurality of diagnosis circuits 6 generate fault diagnosis signals representing results of fault diagnosis of the control unit U1 based on a test signal T1. The test signal T1 is a signal that periodically switches between a first signal in the same phase as a drive signal D1 and a second signal in a different phase from the drive signal D1 by 90 degrees.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates generally to gyro sensors, and more particularly to a gyro sensor that performs fault diagnosis using a test signal. [Background technology]

[0002] The sensing device (gyro sensor) described in Patent Document 1 detects an angular velocity. The sensing device includes a MEMS gyroscope (vibrator), a rate feedback loop (detection feedback circuit), 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 then finally detected from the quadrature feedback loop. This allows the sensing device to monitor the entire system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2014 / 250970 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a gyro sensor that can improve the accuracy of fault diagnosis using a test signal. [Means for solving the problem]

[0005] A gyro sensor according to an embodiment of the present disclosure includes a vibrator, a plurality of electrodes, and a control unit. The plurality of electrodes include a drive electrode, a detection electrode, and a quadrature correction electrode. The plurality of electrodes are arranged to face the vibrator, and form a capacitance between the vibrator and the control unit. The control unit is connected to the drive electrode, the detection electrode, and the quadrature correction electrode. The control unit has a drive circuit, a conversion circuit, a first demodulation circuit, a detection processing circuit, a second demodulation circuit, a quadrature feedback circuit, a test signal generation unit, and a plurality of diagnostic circuits. The drive circuit outputs a drive signal to the drive electrode to induce drive vibration of the vibrator. The conversion circuit converts a detection signal output from the detection electrode. The first demodulation circuit is connected to a subsequent stage of the conversion circuit, and generates a demodulated detection signal by demodulating a signal component in phase with the drive signal from the detection signal converted by the conversion circuit. The detection processing circuit is connected to a rear stage of the first demodulation circuit, and generates an angular velocity signal representing the angular velocity of the vibrator based on the demodulated detection signal. The second demodulation circuit has an input terminal connected to an electric path between the conversion circuit and the first demodulation circuit, and generates a quadrature signal by demodulating a signal component of the detection signal converted by the conversion circuit, the signal component having a phase difference of 90 degrees from the drive signal. The quadrature feedback circuit is inserted between the second demodulation circuit and the quadrature correction electrode, and generates a voltage to be applied to the quadrature correction electrode based on the quadrature signal. The test signal generation unit has an output terminal connected to an electric path between the detection electrode and the conversion circuit, and adds a test signal for fault diagnosis to the detection signal via the output terminal and outputs the test signal to the conversion circuit. The plurality of diagnostic circuits generate a fault diagnosis signal representing a result of fault diagnosis of the control unit based on the test signal. The plurality of diagnostic circuits include a first diagnostic circuit and a second diagnostic circuit. The first diagnostic circuit has an input terminal connected to an electrical path between the first demodulation circuit and the detection processing circuit, and the second diagnostic circuit has an input terminal connected to an electrical path between the second demodulation circuit and the quadrature feedback circuit.The test signal is a signal that periodically switches between a first signal that is in phase with the drive signal and a second signal that is out of phase with the drive signal by 90 degrees. Effect of the Invention

[0006] The present disclosure has an advantage of being able to improve the accuracy of fault diagnosis using test signals. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing a circuit configuration of a gyro sensor according to an embodiment. [Diagram 2] FIG. 2 is a signal waveform diagram of the gyro sensor of the above embodiment. [Diagram 3] FIG. 3 is a block diagram showing a circuit configuration of a main part of a test signal generating unit of the gyro sensor according to the embodiment of the present invention. [Figure 4] FIG. 4 is a frequency distribution diagram of the signal of the gyro sensor of the above embodiment. [Diagram 5] FIG. 5 is a block diagram showing a circuit configuration of a test signal generating unit of a gyro sensor according to a first modified example. [Figure 6] FIG. 6 is a signal waveform diagram of the gyro sensor according to the second modified example. [Figure 7] FIG. 7 is a block diagram showing a circuit configuration of a main part of a test signal generating unit of the gyro sensor according to the embodiment of the present invention. [Figure 8] FIG. 8 is a signal waveform diagram according to the third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (Embodiment) The capacitive gyro sensor 1 according to the embodiment will be described below with reference to the drawings. However, the embodiment described below is merely one of various embodiments of the present disclosure. The embodiment described below can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Also, each figure described in the embodiment described below is a schematic diagram, and the ratio of the size and thickness of each component in the figure does not necessarily reflect the actual dimensional ratio.

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

[0010] The term "terminal" in the present disclosure may be any component capable of being electrically connected to another component. The term "terminal" may be a component such as a connector for connecting electric wires, or may be a part of a conductor such as a wire, a printed wiring, or a metal wiring in a semiconductor.

[0011] In Fig. 1, the drive signal D1 is a carrier wave. In Fig. 1, the detection signal S1, the test signal T1, the signal ST1, and the signal ST2 are signals including a carrier wave and a baseband signal superimposed (modulated) on the carrier wave.

[0012] The signal ST1 is a signal obtained by adding the detection signal S1 and the test signal T1. The signal ST2 is a signal obtained by converting the signal ST1 as a current signal into a voltage signal. The demodulated signal ST3 is a signal obtained by demodulating the signal component of the signal ST2 that has the same phase as the drive signal D1. The demodulated signal ST4 is a signal obtained by demodulating the signal component of the signal ST2 that has a phase difference of 90 degrees from the drive signal D1.

[0013] In the following description, the three diagnostic circuits 6 in FIG. 1 will also be referred to as a first diagnostic circuit 61, a second diagnostic circuit 62, and a third diagnostic circuit 63, respectively.

[0014] (overview) As shown in FIG. 1, the gyro sensor 1 of this embodiment includes a vibrator 10, a plurality of electrodes 2, and a control unit U1. The plurality of electrodes 2 include a driving electrode 21, a detection electrode 22, and a quadrature correction electrode 24. The plurality of electrodes 2 are arranged to face the vibrator 10, and form a capacitance between the vibrator 10 and the control unit U1. The control unit U1 is connected to the driving electrode 21, the detection electrode 22, and the quadrature correction electrode 24. The control unit U1 has a driving circuit 31, a conversion circuit 41, a first demodulation circuit 42, a detection processing circuit 33, a second demodulation circuit 51, a quadrature feedback circuit 53, a test signal generation unit 34, and a plurality of diagnostic circuits 6. The driving circuit 31 outputs a driving signal D1 to the driving electrode 21 to induce driving vibration of the vibrator 10. The conversion circuit 41 converts the detection signal S1 output from the detection electrode 22. The first demodulation circuit 42 is connected to the rear of the conversion circuit 41, and generates a demodulated detection signal by demodulating a signal component having the same phase as the drive signal D1 from the detection signal S1 converted by the conversion circuit 41. The detection processing circuit 33 is connected to the rear of the first demodulation circuit 42, and generates an angular velocity signal representing the angular velocity of the vibrator 10 based on the demodulated detection signal. The second demodulation circuit 51 has an input terminal 513 connected to an electric path between the conversion circuit 41 and the first demodulation circuit 42, and generates a quadrature signal by demodulating a signal component having a phase difference of 90 degrees from the drive signal D1 from the detection signal S1 converted by the conversion circuit 41. The quadrature feedback circuit 53 is inserted between the second demodulation circuit 51 and the quadrature correction electrode 24, and generates a voltage to be applied to the quadrature correction electrode 24 based on the quadrature signal. The test signal generating unit 34 has an output terminal 344 connected to the electrical path between the detection electrode 22 and the conversion circuit 41, and adds a test signal T1 for fault diagnosis to the detection signal S1 via the output terminal 344 and outputs the result to the conversion circuit 41. The multiple diagnostic circuits 6 generate a fault diagnosis signal representing the result of the fault diagnosis of the control unit U1 based on the test signal T1. The multiple diagnostic circuits 6 include a first diagnostic circuit 61 and a second diagnostic circuit 62. The first diagnostic circuit 61 has an input terminal 613 connected to the electrical path between the first demodulation circuit 42 and the detection processing circuit 33. The second diagnostic circuit 62 has an input terminal 623 connected to the electrical path between the second demodulation circuit 51 and the quadrature feedback circuit 53.The test signal T1 is a signal that periodically switches between a first signal that is in phase with the drive signal D1 and a second signal that is 90 degrees out of phase with the drive signal D1 (see FIG. 2).

[0015] According to the above configuration, the first diagnostic circuit 61 can generate a fault diagnosis signal based on the test signal T1 (more specifically, the demodulated signal of the first signal), and the second diagnostic circuit 62 can generate a fault diagnosis signal based on the test signal T1 (more specifically, the demodulated signal of the second signal). Thus, the first diagnostic circuit 61 can perform fault diagnosis of the circuit from the test signal generating unit 34 to the first diagnostic circuit 61, and the second diagnostic circuit 62 can perform fault diagnosis of the circuit from the test signal generating unit 34 to the second diagnostic circuit 62.

[0016] In the first diagnostic circuit 61, the test signal T1 is a high-frequency signal compared to the angular velocity component of the vibrator 10, so that the angular velocity component of the vibrator 10 can be easily removed from the signal input to the first diagnostic circuit 61 and the test signal T1 can be extracted. This improves the accuracy of fault diagnosis in the first diagnostic circuit 61. Also, the test signal T1 can be easily removed from the signal input to the detection processing circuit 33 and the angular velocity component of the vibrator 10 can be extracted. This improves the accuracy of angular velocity detection in the detection processing circuit 33.

[0017] Furthermore, in the second diagnostic circuit 62, the test signal T1 is a high-frequency signal compared to the quadrature signal, so that the quadrature signal can be easily removed from the signal input to the second diagnostic circuit 62 and the test signal T1 can be extracted. This improves the accuracy of fault diagnosis in the second diagnostic circuit 62. Furthermore, the test signal T1 can be easily removed from the signal input to the quadrature feedback circuit 53 and the quadrature signal can be extracted.

[0018] In addition, since the test signal T1 is a high-frequency signal compared to the angular velocity components and quadrature signals of the vibrator 10, the performance required for a filter necessary to separate the test signal T1 from the angular velocity components and quadrature signals of the vibrator 10 is reduced.

[0019] (detail) The gyro sensor 1 of the present embodiment will be described in more detail below.

[0020] (1) Overall structure As shown in FIG. 1, the gyro sensor 1 includes a vibrator 10, a plurality of electrodes 2 (eight in FIG. 1), and a control unit U1.

[0021] The plurality of electrodes 2 includes two drive electrodes 21, two detection electrodes 22, two detection control electrodes 23, and two quadrature correction electrodes 24.

[0022] The control unit U1 has a drive circuit 31, a first connection circuit 32, a detection processing circuit 33, a test signal generation unit 34, a conversion circuit 41, a first demodulation circuit 42, a detection feedback circuit 43, a second demodulation circuit 51, a second connection circuit 52, a quadrature feedback circuit 53, and multiple (three in FIG. 1) diagnostic circuits 6.

[0023] In the gyro sensor 1, a signal having the same phase as the drive signal D1, out of the detection signal S1 output from the detection electrode 22, is fed back to the vibrator 10 through a detection loop circuit L1. The detection loop circuit L1 includes the vibrator 10, a conversion circuit 41, a first demodulation circuit 42, and a detection feedback circuit 43.

[0024] In the gyro sensor 1, a detection signal S1 output from the detection electrode 22, which has a phase difference of 90 degrees with respect to the drive signal D1, is fed back to the vibrator 10 through the quadrature loop circuit L2. The quadrature loop circuit L2 includes the vibrator 10, a conversion circuit 41, a second demodulation circuit 51, a second connection circuit 52, and a quadrature feedback circuit 53.

[0025] Of the detection signal S1, a signal that is out of phase with the drive signal D1 by 90 degrees is also called a quadrature signal, an orthogonal signal, or an unwanted signal.

[0026] (2) A vibrator and multiple electrodes The vibrator 10 is formed of a material including, for example, single crystal silicon, polycrystalline silicon, etc. The shape of the vibrator 10 is, for example, a disk shape.

[0027] The plurality of electrodes 2 are arranged around the vibrator 10 with a gap between them. Each of the plurality of electrodes 2 has a facing surface facing the vibrator 10.

[0028] The electrodes 2 are preferably arranged in pairs in a one-to-one correspondence. The electrodes 2 of this embodiment include two driving electrodes 21 corresponding to each other, two detection electrodes 22 corresponding to each other, two detection control electrodes 23 corresponding to each other, and two quadrature correction electrodes 24.

[0029] 1, the two corresponding electrodes 2 are illustrated as being adjacent to each other, but it is preferable that the two corresponding electrodes 2 are disposed on opposite sides of each other with respect to the center of the vibrator 10. In other words, it is preferable that the vibrator 10 is disposed between the two corresponding electrodes 2.

[0030] (3) Drive circuit The drive circuit 31 is connected to the two drive electrodes 21. The drive circuit 31 outputs (applies) a drive signal D1 to each of the two drive electrodes 21. The drive signal D1 is a voltage signal. In this embodiment, the drive signal D1 is described as having a sine wave waveform, but the drive signal D1 may have a rectangular wave waveform. The drive circuit 31 outputs drive signals D1 of opposite phases to each other to the two drive electrodes 21.

[0031] When a drive signal D1 is output to at least one drive electrode 21, the vibrator 10 periodically vibrates (expands and contracts) due to an electrostatic force between the vibrator 10 and the at least one drive electrode 21. This vibration is referred to as drive vibration in this disclosure.

[0032] The frequency of the drive signal D1 is, for example, not less than 1 MHz and not more than 10 MHz.

[0033] (4) Conversion circuit When the vibrator 10 rotates, the Coriolis force causes the vibrator 10 to resonate. Then, the distance between the vibrator 10 and the two detection electrodes 22 changes according to the angular velocity of the vibrator 10, and the capacitance between the vibrator 10 and the two detection electrodes 22 also changes. A detection signal S1 according to the magnitude of the capacitance is output from the two detection electrodes 22. The detection signal S1 is a signal according to the magnitude of the angular velocity of the vibrator 10.

[0034] The frequency (peak frequency) of the detection signal S1 is equal to the frequency of the drive signal D1. In this disclosure, "equal" is not limited to a completely equal state, but also includes a difference within a practically acceptable range. For example, if the difference between the frequency of the detection signal S1 and the frequency of the drive signal D1 is within a range of 0.2% or less of either value, the frequency of the detection signal S1 and the frequency of the drive signal D1 may be considered to be "equal" and the present disclosure may be applied.

[0035] The conversion circuit 41 is connected to the two detection electrodes 22. The conversion circuit 41 is a circuit that converts the detection signal S1 output from each of the two detection electrodes 22. The conversion circuit 41 may be, for example, a circuit that performs CV conversion (conversion from capacitance to voltage) or IV conversion (conversion from current to voltage) of the detection signal S1. The conversion circuit 41 of this embodiment includes a transimpedance amplifier 411, and performs IV conversion of the detection signal S1.

[0036] The test signal generating unit 34 is connected to the electric path between the conversion circuit 41 and the two detection electrodes 22. The signal input to the conversion circuit 41 is a signal ST1 obtained by adding together the detection signals S1 output from the two detection electrodes 22 and the test signal T1 output from the test signal generating unit 34. That is, the conversion circuit 41 converts the signal ST1 including the detection signal S1. The conversion circuit 41 outputs the converted signal ST2 (voltage signal).

[0037] Since the conversion circuit 41 includes the transimpedance amplifier 411, it is possible to simplify the configuration of the connection portion between the test signal generating unit 34 and the conversion circuit 41. Specifically, it is possible to add the detection signal S1 and the test signal T1 by simply connecting the detection electrode 22 and the output terminal 344 of the test signal generating unit 34 without using an adder.

[0038] (5) Test signal generator The test signal generating section 34 generates a test signal T 1 and outputs it to the conversion circuit 41 .

[0039] As described above, the test signal T1 is a signal in which the first signal and the second signal are switched periodically. More specifically, in this embodiment, as shown in Fig. 2, the test signal T1 is a signal in which the first signal and the second signal are switched alternately. In this embodiment, the waveforms of the first signal and the second signal are described as sine waves, but the waveforms of the first signal and the second signal may be square waves.

[0040] The first and second signals have the same waveform but are out of phase with each other by 90 degrees. The second signal is delayed in phase from the first signal by 90 degrees.

[0041] The test signal T1 is generated based on the drive signal D1. Specifically, the first signal is equal to a portion of the drive signal D1, and the second signal is a signal obtained by changing the phase of a portion of the drive signal D1. In other words, the test signal T1 is a signal obtained by periodically switching the phase of the drive signal D1.

[0042] Therefore, the frequency of the first signal and the second signal is the same as the frequency of the drive signal D1. The frequency of the first signal and the second signal is, for example, not less than 1 MHz and not more than 10 MHz.

[0043] The length of time from the start point ta1 of the first signal to the start point tb1 of the next first signal is defined as the switching period between the first and second signals. The inverse of the switching period between the first and second signals (the frequency corresponding to the switching period) is, for example, 10 kHz or more and 100 kHz or less. The switching period between the first and second signals coincides with the length of time from the start point ta2 of the second signal to the start point tb2 of the next second signal.

[0044] As shown in FIG. 1, the test signal generating section 34 includes a circuit 341, two resistors 342, two capacitors 343, and two output terminals 344.

[0045] The circuit 341 generates a test signal T1.

[0046] A first end of a series circuit of a resistor 342 and a capacitor 343 is connected to each of the two output terminals of the circuit 341. A second end of the series circuit is connected to an output terminal 344. The test signal T1 passes through the series circuit and is output from the output terminal 344.

[0047] The capacitor 343 cuts the DC component of the test signal T1, thereby making it possible to prevent the conversion circuit 41 and the test signal generating section 34 from sharing a DC bias.

[0048] 3 is a block diagram showing an example of the configuration of the circuit 341. The circuit 341 has a phase adjustment unit 351, a multiplexer 352, an amplitude adjustment unit 353, and a VI conversion unit 354.

[0049] The phase adjustment unit 351 divides the drive signal D1 into two signals, and advances the phase of one of the two signals by 45 degrees and delays the phase of the other signal by 45 degrees. As a result, the two signals become a first signal and a second signal whose phase is delayed by 90 degrees relative to the first signal.

[0050] The multiplexer 352 receives the first signal and the second signal generated by the phase adjustment unit 351. The multiplexer 352 also receives the switching signal W1. The switching signal W1 is a rectangular wave whose signal level alternates between a high level and a low level. The multiplexer 352 selects whether to output the first signal or the second signal based on the switching signal W1. More specifically, the multiplexer 352 outputs the first signal when the signal level of the switching signal W1 is a high level, and outputs the second signal when the signal level of the switching signal W1 is a low level. Therefore, the signal output from the multiplexer 352 is a signal corresponding to the test signal T1. The switching period between the first signal and the second signal of the test signal T1 coincides with the period of the switching signal W1.

[0051] The signal (voltage signal) output from the multiplexer 352 is adjusted to a predetermined amplitude by the amplitude adjustment unit 353, and converted into the test signal T1 as a current signal by the VI conversion unit 354. In this manner, the test signal T1 is generated.

[0052] (6) First demodulation circuit An input terminal of the first demodulation circuit 42 is connected to an output terminal of the conversion circuit 41. The first demodulation circuit 42 includes a mixer 421. The first demodulation circuit 42 demodulates the signal ST2 output from the conversion circuit 41 using the drive signal D1. As a result, the first demodulation circuit 42 generates a demodulated signal ST3 by demodulating a signal component in phase with the drive signal D1 from the signal ST2 output from the conversion circuit 41. That is, the first demodulation circuit 42 demodulates based on the amplitude and phase.

[0053] The demodulated signal ST3 includes a "demodulated detection signal" and a demodulated first signal TD1 (see FIG. 2). The demodulated detection signal is a signal obtained by demodulating a signal component of the detection signal S1 that is in phase with the drive signal D1. The demodulated first signal TD1 is a signal obtained by demodulating a first signal of the test signal T1 that is in phase with the drive signal D1.

[0054] As shown in Fig. 2, when the test signal T1 and the demodulated first signal TD1 are compared on the same time axis, the signal level of the demodulated first signal TD1 is high in the section where the first signal appears, and the signal level of the demodulated first signal TD1 is zero in the section where the first signal does not appear (the section where the second signal appears). The amplitude AM1 of the demodulated first signal TD1 is a magnitude according to the magnitude of the amplitude of the first signal. That is, the larger the amplitude of the first signal, the larger the amplitude AM1 of the demodulated first signal TD1.

[0055] (7) First connection circuit The first connection circuit 32 includes a VI converter 321 and an AD converter 322. The VI converter 321 converts a voltage signal into a current signal. The VI converter 321 includes, for example, a transconductance amplifier. The AD converter 322 converts an analog signal into a digital signal.

[0056] An input terminal of the VI converter 321 is connected to an output terminal of the first demodulation circuit 42. An output terminal of the VI converter 321 is connected to an analog input terminal of the AD converter 322.

[0057] The demodulated signal ST3 output from the first demodulation circuit 42 is converted into a current signal by the VI converter 321 and into a digital signal by the AD converter 322.

[0058] (8) Detection processing circuit An input terminal of the detection processing circuit 33 is connected to a digital output terminal of the AD converter 322. The detection processing circuit 33 generates an angular velocity signal representing the angular velocity of the vibrator 10 based on the demodulated signal ST3. More specifically, the digital signal output from the AD converter 322 is the demodulated signal ST3 in digital format, and is input to the detection processing circuit 33. The demodulated signal ST3 includes a demodulated detection signal and a demodulated first signal TD1. The demodulated detection signal is a signal according to the magnitude of the angular velocity of the vibrator 10, and corresponds to the angular velocity signal.

[0059] The demodulated first signal TD1 is a signal having a frequency corresponding to the switching period between the first signal and the second signal. The demodulated detection signal is a low-frequency signal.

[0060] The detection processing circuit 33 removes the demodulated first signal TD1 from the digital signal output from the first connection circuit 32 using a low-pass filter or the like, and extracts a demodulated detection signal, thereby generating an angular velocity signal.

[0061] (9) First diagnostic circuit The first diagnostic circuit 61 includes a bandpass filter 611 and a comparator 612 .

[0062] An input terminal of the bandpass filter 611 is connected to a digital output terminal of the AD converter 322. The bandpass filter 611 acquires the demodulated signal ST3 via the input terminal. The bandpass filter 611 extracts the demodulated first signal TD1 from the demodulated signal ST3.

[0063] The comparator 612 evaluates the magnitude of the amplitude AM1 of the demodulated first signal TD1 extracted by the bandpass filter 611. Specifically, the comparator 612 judges whether the amplitude AM1 is within a predetermined range. If the amplitude AM1 is within the predetermined range, the comparator 612 outputs a normal notification signal, and if the amplitude AM1 is outside the predetermined range, the comparator 612 outputs an abnormality notification signal. The normal notification signal is a signal indicating that the circuit from the test signal generating unit 34 to the first diagnostic circuit 61 is in a normal state. The abnormality notification signal is a signal indicating that the circuit from the test signal generating unit 34 to the first diagnostic circuit 61 is in an abnormal state. For example, when the gain of the circuit is abnormal, the comparator 612 outputs the abnormality notification signal. That is, the first diagnostic circuit 61 judges with what degree of gain the test signal T1 is amplified or attenuated in the circuit.

[0064] The circuits from the test signal generating unit 34 to the first diagnostic circuit 61 include the test signal generating unit 34, the conversion circuit 41, the first demodulation circuit 42, the first connection circuit 32, and the first diagnostic circuit 61. That is, the first diagnostic circuit 61 uses the test signal T1 (demodulated first signal TD1) to determine the presence or absence of an abnormality in these circuits.

[0065] The comparator 612 outputs the determination result (a normality notification signal or an abnormality notification signal) to, for example, a storage device. The storage device stores the determination result. The storage device stores the determination result together with, for example, information on the time when the determination was made.

[0066] (10) Detection feedback circuit The detection feedback circuit 43 includes a chopper circuit 431, a VI converter 432, a circuit 433, and a transimpedance amplifier 434. The detection feedback circuit 43 is inserted between the first demodulation circuit 42 and the detection control electrode 23. That is, the input terminal and the output terminal of the detection feedback circuit 43 are connected to the first demodulation circuit 42 and the detection control electrode 23, respectively.

[0067] The demodulated signal ST3 output from the first demodulation circuit 42 is input to the detection feedback circuit 43. The detection feedback circuit 43 generates a voltage to be applied to the two detection control electrodes 23 based on the demodulated detection signal included in the demodulated signal ST3.

[0068] The chopper circuit 431, when used in conjunction with the circuit 433, reduces noise of the VI converter 432 superimposed on the demodulated signal ST3 output from the first demodulation circuit 42. The VI converter 432 converts the demodulated signal ST3 output from the chopper circuit 431 as a voltage signal into a current signal. The circuit 433 includes a modulator that performs AM modulation (amplitude modulation) on the demodulated signal ST3 using the drive signal D1 as a carrier wave. The transimpedance amplifier 434 converts the demodulated signal ST3 modulated by the drive signal D1 from a current signal into a voltage signal.

[0069] The output terminals of the transimpedance amplifier 434 are connected to the two detection control electrodes 23. In addition, the output terminal of the transimpedance amplifier 434 is connected to the third diagnostic circuit 63.

[0070] By applying a voltage to the two detection control electrodes 23 from the detection feedback circuit 43, the amplitude of the resonant vibration of the vibrator 10 according to the angular velocity of the vibrator 10 decreases. As a result, the amplitude of the angular velocity component of the detection signal S1 decreases relative to the magnitude of the angular velocity of the vibrator 10. Therefore, the gyro sensor 1 can detect a larger angular velocity. In other words, the dynamic range of the gyro sensor 1 is expanded.

[0071] (11) Third diagnostic circuit The third diagnostic circuit 63 includes a demodulation circuit 634 , a low-pass filter 631 , and a comparator 632 .

[0072] An input terminal of the demodulation circuit 634 is connected to the output terminal of the transimpedance amplifier 434. The demodulation circuit 634 demodulates the signal output from the detection feedback circuit 43 by using the drive signal D1.

[0073] An input terminal of the low-pass filter 631 is connected to an output terminal of the demodulation circuit 634. The low-pass filter 631 extracts a demodulated first signal TD1 from the signal demodulated by the demodulation circuit 634.

[0074] The comparator 632 evaluates the magnitude of the amplitude AM1 of the demodulated first signal TD1 extracted by the low-pass filter 631. Specifically, the comparator 632 judges whether the amplitude AM1 is within a predetermined range. If the amplitude AM1 is within the predetermined range, the comparator 632 outputs a normal notification signal, and if the amplitude is outside the predetermined range, the comparator 632 outputs an abnormality notification signal. The normal notification signal is a signal indicating that the circuit from the test signal generating unit 34 to the third diagnostic circuit 63 is in a normal state. The abnormality notification signal is a signal indicating that the circuit from the test signal generating unit 34 to the third diagnostic circuit 63 is in an abnormal state. For example, when the gain of the circuit is abnormal, the comparator 632 outputs the abnormality notification signal. That is, the third diagnostic circuit 63 judges with what degree of gain the test signal T1 is amplified or attenuated in the circuit.

[0075] The circuits from the test signal generating unit 34 to the third diagnostic circuit 63 include the test signal generating unit 34, the conversion circuit 41, the first demodulation circuit 42, the detection feedback circuit 43, and the third diagnostic circuit 63. That is, the third diagnostic circuit 63 uses the test signal T1 (demodulated first signal TD1) to determine the presence or absence of an abnormality in these circuits.

[0076] The comparator 632 outputs the determination result (a normality notification signal or an abnormality notification signal) to, for example, a storage device. The storage device stores the determination result. The storage device stores the determination result together with, for example, information on the time when the determination was made.

[0077] (12) Second demodulation circuit The second demodulation circuit 51 includes a phase shifter 511 and a mixer 512 .

[0078] The phase shifter 511 shifts the phase of the drive signal D1 and outputs the signal to the mixer 512. More specifically, the phase shifter 511 shifts the phase of the drive signal D1 by 90 degrees and outputs the signal to the mixer 512.

[0079] An input terminal of the mixer 512 is connected to an electric path between the conversion circuit 41 and the first demodulation circuit 42. A signal ST2 is input from the conversion circuit 41 to the mixer 512. The mixer 512 demodulates the signal ST2 using the signal input from the phase shifter 511. As a result, the second demodulation circuit 51 generates a demodulated signal ST4 by demodulating a signal component having a phase difference of 90 degrees from the drive signal D1, out of the signal ST2 output from the conversion circuit 41. That is, the second demodulation circuit 51 demodulates the signal ST2 based on the amplitude and phase.

[0080] The demodulated signal ST4 includes a demodulated second signal TD2 (see FIG. 2). The demodulated second signal TD2 is a signal obtained by demodulating a second signal of the test signal T1, which has a phase difference of 90 degrees with the drive signal D1.

[0081] Furthermore, the demodulated signal ST4 may include a “quadrature signal.” The quadrature signal is a signal obtained by demodulating a signal component of the detection signal S1 that is out of phase with the drive signal D1 by 90 degrees.

[0082] As shown in Fig. 2, when the test signal T1 and the demodulated second signal TD2 are compared on the same time axis, the signal level of the demodulated second signal TD2 is high in the section where the second signal appears, and the signal level of the demodulated second signal TD2 is zero in the section where the second signal does not appear (the section where the first signal appears). The amplitude AM2 of the demodulated second signal TD2 is a magnitude according to the magnitude of the amplitude of the second signal. That is, the larger the amplitude of the second signal, the larger the amplitude AM2 of the demodulated second signal TD2.

[0083] (13) Second connection circuit The second connection circuit 52 includes an amplifier 521 and an AD converter 522 .

[0084] An input terminal of the amplifier 521 is connected to an output terminal of the second demodulation circuit 51. The amplifier 521 amplifies the demodulated signal ST4 output from the second demodulation circuit 51. An output terminal of the amplifier 521 is connected to an analog input terminal of the AD converter 522. The AD converter 522 converts the demodulated signal ST4 output from the amplifier 521 from an analog signal to a digital signal.

[0085] (14) Second diagnostic circuit The second diagnostic circuit 62 includes a band-pass filter 621 and a comparator 622 .

[0086] An input terminal of the bandpass filter 621 is connected to the digital output terminal of the AD converter 522. The bandpass filter 621 acquires the demodulated signal ST4 via the input terminal. The bandpass filter 621 extracts the demodulated second signal TD2 from the demodulated signal ST4.

[0087] The comparator 622 evaluates the magnitude of the amplitude AM2 of the demodulated second signal TD2 extracted by the bandpass filter 621. Specifically, the comparator 622 judges whether the amplitude AM2 is within a predetermined range. If the amplitude AM2 is within the predetermined range, the comparator 622 outputs a normal notification signal, and if the amplitude AM2 is outside the predetermined range, the comparator 622 outputs an abnormality notification signal. The normal notification signal is a signal indicating that the circuit from the test signal generating unit 34 to the second diagnostic circuit 62 is in a normal state. The abnormality notification signal is a signal indicating that the circuit from the test signal generating unit 34 to the second diagnostic circuit 62 is in an abnormal state. For example, when the gain of the circuit is abnormal, the comparator 622 outputs the abnormality notification signal. That is, the second diagnostic circuit 62 judges with what degree of gain the test signal T1 is amplified or attenuated in the circuit.

[0088] The circuits from the test signal generating unit 34 to the second diagnostic circuit 62 include the test signal generating unit 34, the conversion circuit 41, the second demodulation circuit 51, the second connection circuit 52, and the second diagnostic circuit 62. That is, the second diagnostic circuit 62 uses the test signal T1 (demodulated second signal TD2) to determine the presence or absence of an abnormality in these circuits.

[0089] The comparator 622 outputs the determination result (a normality notification signal or an abnormality notification signal) to, for example, a storage device. The storage device stores the determination result. The storage device stores the determination result together with, for example, information on the time when the determination was made.

[0090] (15) Quadrature feedback circuit The quadrature feedback circuit 53 includes a low-pass filter 531 .

[0091] The demodulated signal ST4 output from the second connection circuit 52 is input to the quadrature feedback circuit 53. The quadrature feedback circuit 53 generates voltages to be applied to the two quadrature correction electrodes 24 based on the demodulated signal ST4.

[0092] An input terminal of the low-pass filter 531 is connected to an output terminal of the second connection circuit 52. An output terminal of the low-pass filter 531 is connected to the two quadrature correction electrodes 24. The low-pass filter 531 removes high-frequency components from the demodulated signal ST4. The harmonic components of the demodulated signal ST4 include the demodulated second signal TD2.

[0093] The quadrature feedback circuit 53 applies voltages to the two quadrature correction electrodes 24, thereby suppressing the second-order mode motion of the vibrator 10. The second-order mode motion causes the detection signal S1 to include a signal component (quadrature signal) that is out of phase with the drive signal D1.

[0094] (16) Diagnostic circuit connection point The three diagnostic circuits 6 are each connected to the rear stage (output side) of the conversion circuit 41. The rear stage of the first demodulation circuit 42 specifically includes the following first to third electric paths. The first electric path is an electric path from the conversion circuit 41 to the detection processing circuit 33 via the first demodulation circuit 42 and the first connection circuit 32. The second electric path is an electric path from the conversion circuit 41 to the two detection control electrodes 23 via the first demodulation circuit 42 and the detection feedback circuit 43. The third electric path is an electric path from the conversion circuit 41 to the two quadrature correction electrodes 24 via the second demodulation circuit 51, the second connection circuit 52, and the quadrature feedback circuit 53.

[0095] The first diagnostic circuit 61 has two input terminals 613 connected to the electrical path between the first demodulation circuit 42 and the detection and processing circuit 33 .

[0096] The second diagnostic circuit 62 has an input terminal 623 connected to the electrical path between the second demodulation circuit 51 and the quadrature feedback circuit 53 .

[0097] The third diagnostic circuit 63 has an input terminal 633 connected to the electrical path between the sensing feedback circuit 43 and the two sensing control electrodes 23 .

[0098] Each of the first to third diagnostic circuits 61 to 63 generates a fault diagnosis signal indicative of the result of the fault diagnosis of the control unit U1 based on the test signal T1. The normality notification signal and the abnormality notification signal described above are examples of the fault diagnosis signal.

[0099] (17) Detection loop circuit As described above, the detection loop circuit L1 includes the vibrator 10, the conversion circuit 41, the first demodulation circuit 42, and the detection feedback circuit 43. The gain of the detection loop circuit L1 is the rate of change in the magnitude of a signal when the signal makes one circuit around the detection loop circuit L1. The gain of the detection loop circuit L1 is determined by the circuit configuration and the Q value of the vibrator 10, etc. Furthermore, the gain of the detection loop circuit L1 depends on the frequency.

[0100] As described above, the switching period between the first signal and the second signal is the length of time from the start point ta1 of the first signal to the start point tb1 of the next first signal. The reciprocal of the switching period is the switching frequency (of the test signal T1) corresponding to the period in which the first signal appears.

[0101] The switching frequency (the inverse of the switching period) of the test signal T1 is a frequency outside the response range of the detection loop circuit L1. The outside the response range of the detection loop circuit L1 is preferably a range in which the gain of the detection loop circuit L1 is 0 dB or less. In other words, in this case, the response range of the detection loop circuit L1 is a range in which the gain of the detection loop circuit L1 is greater than 0 dB.

[0102] If the gain in the detection loop circuit L1 is 0 dB or less for a signal whose frequency is equal to the switching frequency, the switching frequency is outside the response range of the detection loop circuit L1. On the other hand, if the gain in the detection loop circuit L1 is greater than 0 dB for a signal whose frequency is equal to the switching frequency, the switching frequency is within the response range of the detection loop circuit L1.

[0103] If the switching frequency is outside the response range of the detection loop circuit L1, the test signal T1 is attenuated by circulating through the detection loop circuit L1. This reduces the possibility that the test signal T1 will affect the angular velocity signal. In other words, it reduces the possibility that the test signal T1 will interfere with the detection of the angular velocity in the detection processing circuit 33. Furthermore, each of the multiple diagnostic circuits 6 can perform fault diagnosis of the control unit U1 using the test signal T1 before it is attenuated.

[0104] For example, the test signal T1 reaches the first diagnostic circuit 61, the second diagnostic circuit 62, and the third diagnostic circuit 63. However, even if the test signal T1 is output to the detection control electrode 23 near the third diagnostic circuit 63, the vibrator 10 is insensitive to the frequency of the test signal T1 (i.e., the vibrator 10 does not vibrate due to the test signal T1), so the detection signal S1 output from the detection electrode 22 does not include a signal component of the test signal T1. That is, as an example, the test signal T1 is attenuated to a level that can be regarded as a zero level in the vibrator 10.

[0105] As a comparative example of this embodiment, a configuration in which the configuration disclosed in Patent Document 1 is applied to the gyro sensor 1 of FIG. 1 is assumed. In the comparative example, the configuration corresponding to this embodiment is given the same reference numerals. In the comparative example, the test signal T1 output to the detection feedback circuit 43 needs to be output from the vibrator 10 to the second diagnostic circuit 62 via the conversion circuit 41 and the second demodulation circuit 51. Therefore, in the comparative example, it is necessary to select a vibrator 10 with a wide response range for the transmission of the test signal T1, such as the vibrator 10 being vibrated by the test signal T1. In contrast, in the gyro sensor 1 of this embodiment, it is not necessary to set the response range of the vibrator 10 itself wide for the transmission of the test signal T1, so that the design freedom is higher than that of the comparative example (Patent Document 1).

[0106] Furthermore, in the gyro sensor 1 of this embodiment, increasing the sensitivity to angular velocity by decreasing the feedback amount of the detection loop circuit L1 does not prevent the test signal T1 from reaching the multiple diagnostic circuits 6. Therefore, in this embodiment, it is possible to provide a gyro sensor 1 that is highly sensitive to angular velocity.

[0107] In addition, it is more preferable that the outside of the response range of the detection loop circuit L1 is a range in which the gain of the detection loop circuit L1 is −3 dB or less. In this case, the test signal T1 attenuates more rapidly, so that the possibility that the test signal T1 affects the angular velocity signal can be reduced.

[0108] (18) Test signal The switching frequency of the test signal T1 is lower than the frequency of the drive signal D1.

[0109] The switching frequency of the test signal T1 is assumed to be, for example, 10 kHz or more and 100 kHz or less. If the switching frequency of the test signal T1 is within this range, it is easy to design the vibrator 10 to be insensitive to the test signal T1. Furthermore, if the switching frequency of the test signal T1 is within this range, the switching frequency of the test signal T1 is significantly different from the frequency of the demodulated detection signal (signal corresponding to angular velocity), which is a low-frequency component, so that the test signal T1 can be easily extracted by the band-pass filters 611, 621 and the low-pass filter 631 of each of the three diagnostic circuits 6. Therefore, the performance required of the band-pass filters 611, 621 and the low-pass filter 631 is also relatively low.

[0110] In the configuration of the comparative example described above, the test signal T1 needs to be a low-frequency signal in order to vibrate the vibrator 10 with the test signal T1, and a low-pass filter with a low cutoff frequency is required to extract the test signal T1 from a signal including the test signal T1 and the demodulated detection signal (low-frequency signal), which reduces the response speed when detecting the test signal T1. In the gyro sensor 1 of this embodiment, the switching frequency of the test signal T1 is set to a frequency outside the response range of the detection loop circuit L1, thereby solving this problem.

[0111] The test signal T1 is a signal that periodically switches between a first signal and a second signal that are different in phase from each other. As a result, a part of the test signal T1 is transmitted to the electric circuit on the detection processing circuit 33 side as viewed from the first demodulation circuit 42, the detection feedback circuit 43, and the circuit downstream of the second demodulation circuit 51. Specifically, a demodulated first signal TD1 obtained by demodulating the test signal T1 with the drive signal D1 is transmitted to the electric circuit on the detection processing circuit 33 side as viewed from the first demodulation circuit 42 and the detection feedback circuit 43, and a demodulated second signal TD2 obtained by demodulating the test signal T1 with a signal whose phase is shifted by 90 degrees from the drive signal D1 is transmitted to the circuit downstream of the second demodulation circuit 51. Therefore, fault diagnosis using the test signal T1 is possible in each of the first diagnostic circuit 61 connected to the circuit on the detection processing circuit 33 side as viewed from the first demodulation circuit 42, the third diagnostic circuit 63 connected to the detection feedback circuit 43, and the second diagnostic circuit 62 connected to the circuit downstream of the second demodulation circuit 51.

[0112] (19) Demodulated signal The demodulated signal ST3 input to the detection processing circuit 33, the first diagnostic circuit 61, and the third diagnostic circuit 63 is a signal obtained by adding a demodulated detection signal (low frequency component) which is an angular velocity component of the vibrator 10 to the demodulated first signal TD1 (see FIG. 2) derived from the test signal T1. The demodulated signal ST4 input to the quadrature feedback circuit 53 and the second diagnostic circuit 62 is a signal obtained by adding a quadrature signal (low frequency component) included in the detection signal S1 to the demodulated second signal TD2 (see FIG. 2) derived from the test signal T1.

[0113] FIG. 4 shows a schematic diagram of the result of fast Fourier transform of the demodulated signal ST3 or ST4. 0 is the frequency of the demodulated detection signal or quadrature signal, f T is the switching frequency of the test signal T1. In order to extract the components originating from the test signal T1 from the demodulated signals ST3 and ST4, a band-pass filter (f 0 ±f T) is extracted. In order to extract the demodulated detection signal or quadrature signal from the demodulated signal ST3 or ST4, a band pass filter is used to filter out the demodulated detection signal or quadrature signal. 0 It is only necessary to extract a signal in a frequency band including the above.

[0114] Since the test signal T1 is a signal that periodically switches between a first signal and a second signal, the frequency of the test signal T1 and the frequency of the detection signal S1 (demodulated detection signal or quadrature signal) are separated from each other, and it is easily possible to separate them from each other based on frequency.

[0115] (20) Variations Modifications of the embodiment are listed below. The following modifications may be implemented in appropriate combination. Hereinafter, the configuration of the embodiment described above will be referred to as a basic example.

[0116] (20.1) First Modification A test signal generating section 34A according to a first modified example is shown in Fig. 5. Components similar to those in the test signal generating section 34 of Fig. 1 are given the same reference numerals and descriptions thereof will be omitted.

[0117] 5, the test signal generating unit 34A includes two T-type network resistors 345 instead of the two resistors 342. The test signal T1 generated by the circuit 341 passes through the two T-type network resistors 345 and is output from two output terminals 344.

[0118] Each of the two T-type resistor networks 345 includes resistors R1, R2, and R3. The resistors R1 and R3 are connected in series. A resistor R2 is inserted between the electric path between the resistors R1 and R3 and ground. The series circuit of the resistors R1 and R3 is inserted between the output terminal of the circuit 341 and the capacitor 343. Note that the ground here includes an AC (alternating current) ground and a reference potential in the control unit U1.

[0119] According to this modified example, the resistance values ​​of the resistors R1, R2, and R3 used can be made small, and the effect of the parasitic capacitance of the resistors R1, R2, and R3 can be reduced, thereby enabling the test signal generating unit 34A to output a relatively small current signal as the test signal T1.

[0120] (20.2) Second Modification FIG. 6 illustrates the test signal T1, the demodulated first signal TD1, and the demodulated second signal TD2 in the second modified example.

[0121] In this modification, the test signal T1 is a signal that periodically switches between a first signal, a second signal, a third signal, and a fourth signal. The third signal is a signal that is 180 degrees out of phase with (180 degrees delayed from) the drive signal D1. The fourth signal is a signal that is 270 degrees out of phase with (270 degrees delayed from) the drive signal D1.

[0122] More specifically, the test signal T1 is a signal that repeatedly switches from the first signal to the second signal, from the second signal to the third signal, from the third signal to the fourth signal, and from the fourth signal to the first signal. Thus, as time passes, the start point ta1 of the first signal, the start point ta2 of the second signal, the start point ta3 of the third signal, and the start point ta4 of the fourth signal come in this order, and then again the start point tb1 of the first signal, the start point tb2 of the second signal, the start point tb3 of the third signal, and the start point tb4 of the fourth signal come in this order.

[0123] The length of time from the start point ta1 of the first signal to the start point tb1 of the next first signal is defined as the switching period of the first, second, third and fourth signals. In other words, the test signal T1 is a signal that repeats the same waveform every switching period. The reciprocal of the switching period is the switching frequency (of the test signal T1) that corresponds to the period in which the first signal appears.

[0124] The first demodulation circuit 42 demodulates the test signal T1 by the drive signal D1 to generate a demodulated signal ST3. The demodulated signal ST3 is a signal obtained by adding the demodulated first signal TD1 to the demodulated detection signal. The demodulated detection signal is a signal obtained by demodulating a signal component of the detection signal S1 that is in phase with the drive signal D1. The demodulated first signal TD1 is a signal obtained by demodulating a first signal of the test signal T1 that is in phase with the drive signal D1 as a positive signal, and demodulating a third signal of the test signal T1 that is 180 degrees out of phase with the drive signal D1 as a negative signal. More specifically, in the section where the first signal is present, the signal level of the demodulated first signal TD1 is a predetermined value (positive value), in the section where the third signal is present, the signal level of the demodulated first signal TD1 is (-1) × predetermined value, and in the section where the second signal or the fourth signal is present, the signal level of the demodulated first signal TD1 is zero level.

[0125] The first diagnostic circuit 61 and the third diagnostic circuit 63 obtain the demodulated first signal TD1 included in the demodulated signal ST3 by filtering the demodulated signal ST3. The magnitude of the demodulated first signal TD1 is twice the amplitude AM1. The demodulated first signal TD1 is a signal having a magnitude corresponding to the amplitude of the test signal T1. The demodulated first signal TD1 is a signal having a symmetric waveform with respect to the zero level within the switching period, and does not contain low-frequency components like the demodulated detection signal. The first diagnostic circuit 61 and the third diagnostic circuit 63 output a normal notification signal if the magnitude of the demodulated first signal TD1 is within a predetermined range, and output an abnormality notification signal if the magnitude of the demodulated first signal TD1 is outside the predetermined range.

[0126] The second demodulation circuit 51 demodulates the test signal T1 using a signal obtained by shifting the phase of the drive signal D1 by 90 degrees to generate a demodulated signal ST4. The demodulated signal ST4 is a signal obtained by adding a demodulated second signal TD2 to the quadrature signal. The quadrature signal is a signal obtained by demodulating a signal component of the detection signal S1 whose phase differs by 90 degrees from that of the drive signal D1. The demodulated second signal TD2 is a signal obtained by demodulating a second signal of the test signal T1 whose phase is delayed by 90 degrees from the drive signal D1 as a positive signal, and demodulating a fourth signal of the test signal T1 whose phase is delayed by 270 degrees from the drive signal D1 as a negative signal. More specifically, in the section where the second signal is present, the signal level of the demodulated second signal TD2 becomes a predetermined value (positive value), in the section where the fourth signal is present, the signal level of the demodulated second signal TD2 becomes (-1) x the predetermined value, and in the section where the first signal or the third signal is present, the signal level of the demodulated second signal TD2 becomes zero level.

[0127] The second diagnostic circuit 62 obtains the demodulated second signal TD2 included in the demodulated signal ST4 by filtering the demodulated signal ST4. The magnitude of the demodulated second signal TD2 is twice the amplitude AM2. The demodulated second signal TD2 is a signal having a magnitude corresponding to the amplitude of the test signal T1. The demodulated second signal TD2 is a signal having a waveform symmetrical with respect to the zero level within the switching period, and does not include low-frequency components such as a quadrature signal. If the magnitude of the demodulated second signal TD2 is within a predetermined range, the second diagnostic circuit 62 outputs a normal notification signal, and if the magnitude of the demodulated second signal TD2 is outside the predetermined range, the second diagnostic circuit 62 outputs an abnormality notification signal.

[0128] In this manner, according to this modification, the angular velocity component (demodulated detection signal) of the vibrator 10 and the quadrature signal can be easily removed from the demodulated signals ST3 and ST4, and the component derived from the test signal T1 can be extracted. Then, the diagnostic circuit 6 can determine with what gain the test signal T1 is amplified or attenuated in the control unit U1. Furthermore, since the demodulated first signal TD1 does not contain low-frequency components, the demodulated first signal TD1 is prevented from affecting the angular velocity component (demodulated detection signal) extracted from the demodulated signal ST3 in the detection processing circuit 33. Furthermore, since the demodulated second signal TD2 does not contain low-frequency components, the demodulated second signal TD2 is prevented from affecting the quadrature signal extracted from the demodulated signal ST4 in the quadrature feedback circuit 53.

[0129] The test signal generating section 34 of this modification has a circuit 341B instead of the circuit 341 (see FIG. 3). FIG 7 is a block diagram showing an example of the configuration of the circuit 341B.

[0130] The phase adjustment unit 351 divides the drive signal D1 into two signals, and advances the phase of one of the two signals by 45 degrees and delays the phase of the other signal by 45 degrees. As a result, the two signals become a first signal and a second signal whose phase is delayed by 90 degrees relative to the first signal.

[0131] The first and second signals generated by the phase adjustment unit 351 are positively input to the multiplexer 352. The first and second signals are negatively input to the multiplexer 352. The negatively input first and second signals correspond to the third and fourth signals, respectively.

[0132] The multiplexer 352 further receives a switching signal W1. The switching signal W1 is a square wave whose signal level alternates between a high level and a low level. The multiplexer 352 selects which of the first signal, the second signal, the third signal, and the fourth signal to output based on the switching signal W1. More specifically, the multiplexer 352 alternately outputs the first signal and the third signal each time the signal level of the switching signal W1 becomes a high level, and alternately outputs the second signal and the fourth signal each time the signal level of the switching signal W1 becomes a low level. Therefore, the signal output from the multiplexer 352 is a signal equivalent to the test signal T1.

[0133] (20.3) Third Modification 8 illustrates the test signal T1, the demodulated first signal TD1, and the demodulated second signal TD2 in the third modified example. The test signal T1 in this modified example is the same as that in the second modified example in that the first signal, the second signal, the third signal, and the fourth signal are periodically switched. However, in this modified example, the order in which the first signal, the second signal, the third signal, and the fourth signal appear is different from that in the second modified example.

[0134] 8, the test signal T1 is a signal that repeatedly switches from the first signal to the third signal, from the third signal to the second signal, from the second signal to the fourth signal, and from the fourth signal to the first signal. Even if the test signal T1 is such a signal, it is possible to perform fault diagnosis based on the test signal T1, as in the second modification.

[0135] The order in which the first signal, the second signal, the third signal, and the fourth signal appear within a switching cycle (from start point ta1 to start point tb1) is not limited to the order shown in the second or third modified example, and can be changed arbitrarily. However, it is preferable that the test signal T1 is a signal that repeats the same waveform for each switching cycle. In other words, it is preferable that the order in any switching cycle (from start point ta1 to start point tb1) matches the order in other switching cycles (from start point tb1 to start point tc1).

[0136] It is particularly preferable to generate the test signal T1 so that the first signal, the second signal, the third signal, and the fourth signal appear in this order, as in the second modification example. In this case, it is possible to prevent signals not used for fault diagnosis from appearing in the demodulated first signal TD1 and the demodulated second signal TD2 near the switching frequency of the test signal T1.

[0137] (20.4) Other Modifications Other variations of the embodiment are listed below.

[0138] In a basic example, the second signal lags the first signal by 90 degrees in phase, whereas the second signal may lead the first signal by 90 degrees in phase.

[0139] In the second and third modified examples, the second signal, the third signal, and the fourth signal may be 90 degrees, 180 degrees, and 270 degrees ahead of the phase of the first signal, respectively.

[0140] The conversion circuit 41 may further include a current buffer inserted between the transimpedance amplifier 411 and the two detection electrodes 22 .

[0141] It is not essential that the gyro sensor 1 includes two each of the driving electrodes 21, the detection electrodes 22, the detection control electrodes 23, and the quadrature correction electrodes 24. The number of each of the driving electrodes 21, the detection electrodes 22, the detection control electrodes 23, and the quadrature correction electrodes 24 may be one, or three or more.

[0142] In the gyro sensor 1, the detection control electrode 23, the detection feedback circuit 43, and the third diagnostic circuit 63 are not essential components.

[0143] The transimpedance amplifier 411 of the conversion circuit 41 may be a differential transimpedance amplifier.

[0144] The location where the diagnostic circuit 6 is installed may be any location subsequent to the conversion circuit 41, and is not limited to the location shown in the basic example. The number of diagnostic circuits 6 may be two, a first diagnostic circuit 61 and a second diagnostic circuit 62, or may be four or more.

[0145] In the basic example, the test signal T1 is output to the third diagnostic circuit 63 and is attenuated to a level that can be considered to be a zero level in the vibrator 10. As another example, the test signal T1 may be attenuated to a level that can be considered to be a zero level in the detection feedback circuit 43. In this case, the third diagnostic circuit 63 may be omitted, or the input terminal 633 of the third diagnostic circuit 63 may be connected to an electric path in the detection feedback circuit 43.

[0146] The block diagrams shown in FIGS. 1, 3, 5, and 7 are merely examples of the configuration of the gyro sensor 1 according to the present disclosure, and circuits may be added or omitted as appropriate.

[0147] The executing entity of the gyro sensor 1 or the method of using the gyro sensor 1 in the present disclosure may include a computer system. The computer system is mainly composed of a processor and a memory as hardware. The processor executes a program recorded in the memory of the computer system, thereby realizing at least a part of the function of the executing entity of the gyro sensor 1 or the method of using the gyro sensor 1 in the present disclosure. The program may be pre-recorded in the memory of the computer system, may be provided through an electric communication line, or may be provided by being recorded in a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The integrated circuits such as IC or LSI referred to here are called by different names depending on the degree of integration, and include integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Furthermore, a field-programmable gate array (FPGA) that is programmed after the manufacture of an LSI, or a logic device that allows reconfiguration of the connection relationship within the LSI or reconfiguration of the circuit partition within the LSI, can also be employed as a processor. The electronic circuits may be integrated into one chip, or may be distributed among multiple chips. The chips may be integrated into one device, or may be distributed among multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Thus, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0148] Furthermore, it is not essential for the gyro sensor 1 that multiple functions are concentrated in one housing, and multiple components of the gyro sensor 1 may be distributed across multiple housings.

[0149] Conversely, in the embodiment, at least some of the functions of the gyro sensor 1 that are distributed across multiple housings may be integrated into one housing.

[0150] (summary) The above-described embodiments and the like disclose the following aspects.

[0151] The gyro sensor (1) according to the first aspect includes a vibrator (10), a plurality of electrodes (2), and a control unit (U1). The plurality of electrodes (2) include a driving electrode (21), a detection electrode (22), and a quadrature correction electrode (24). The plurality of electrodes (2) are arranged to face the vibrator (10) and form a capacitance between the vibrator (10). The control unit (U1) is connected to the driving electrode (21), the detection electrode (22), and the quadrature correction electrode (24). The control unit (U1) includes a driving circuit (31), a conversion circuit (41), a first demodulation circuit (42), a detection processing circuit (33), a second demodulation circuit (51), a quadrature feedback circuit (53), a test signal generation unit (34; 34A), and a plurality of diagnostic circuits (6). The drive circuit (31) outputs a drive signal (D1) to the drive electrode (21) to induce drive vibration of the vibrator (10). The conversion circuit (41) converts the detection signal (S1) output from the detection electrode (22). The first demodulation circuit (42) is connected to the rear stage of the conversion circuit (41) and generates a demodulated detection signal by demodulating a signal component in phase with the drive signal (D1) from the detection signal (S1) converted by the conversion circuit (41). The detection processing circuit (33) is connected to the rear stage of the first demodulation circuit (42) and generates an angular velocity signal representing the angular velocity of the vibrator (10) based on the demodulated detection signal. The second demodulation circuit (51) has an input terminal (513) connected to the electric path between the conversion circuit (41) and the first demodulation circuit (42), and generates a quadrature signal by demodulating a signal component of the detection signal (S1) converted by the conversion circuit (41) that is out of phase with the drive signal (D1) by 90 degrees. The quadrature feedback circuit (53) is inserted between the second demodulation circuit (51) and the quadrature correction electrode (24), and generates a voltage to be applied to the quadrature correction electrode (24) based on the quadrature signal. The test signal generation unit (34; 34A) has an output terminal (344) connected to the electric path between the detection electrode (22) and the conversion circuit (41), and adds a test signal (T1) for fault diagnosis to the detection signal (S1) via the output terminal (344) and outputs the result to the conversion circuit (41). A plurality of diagnostic circuits (6) generate fault diagnosis signals representing the results of fault diagnosis of the control unit (U1) based on a test signal (T1).The plurality of diagnostic circuits (6) include a first diagnostic circuit (61) and a second diagnostic circuit (62). The first diagnostic circuit (61) has an input terminal (613) connected to an electric path between the first demodulation circuit (42) and the detection processing circuit (33). The second diagnostic circuit (62) has an input terminal (623) connected to an electric path between the second demodulation circuit (51) and the quadrature feedback circuit (53). The test signal (T1) is a signal that periodically switches between a first signal having the same phase as the drive signal (D1) and a second signal having a phase difference of 90 degrees from that of the drive signal (D1).

[0152] According to the above configuration, the first diagnostic circuit (61) can generate a fault diagnosis signal based on the test signal T1 (more specifically, the demodulated first signal TD1), and the second diagnostic circuit (62) can generate a fault diagnosis signal based on the test signal T1 (more specifically, the demodulated second signal TD2). Thus, the first diagnostic circuit (61) can perform fault diagnosis of the circuit from the test signal generating unit (34; 34A) to the first diagnostic circuit (61), and the second diagnostic circuit (62) can perform fault diagnosis of the circuit from the test signal generating unit (34; 34A) to the second diagnostic circuit (62).

[0153] In the first diagnostic circuit (61), the test signal (T1) is a high-frequency signal compared to the angular velocity component of the vibrator (10), so that the angular velocity component of the vibrator (10) can be easily removed from the signal input to the first diagnostic circuit (61) and the test signal (T1) can be extracted, thereby improving the accuracy of fault diagnosis in the first diagnostic circuit (61).

[0154] In addition, since the test signal (T1) in the second diagnostic circuit (62) is a high-frequency signal compared to the quadrature signal, the quadrature signal can be easily removed from the signal input to the second diagnostic circuit (62) and the test signal (T1) can be extracted, thereby improving the accuracy of fault diagnosis in the second diagnostic circuit (62).

[0155] In the gyro sensor (1) according to the second aspect, in the first aspect, the plurality of electrodes (2) further includes a detection control electrode (23). The control unit (U1) further includes a detection feedback circuit (43). The detection feedback circuit (43) is inserted between the first demodulation circuit (42) and the detection control electrode (23), and generates a voltage to be applied to the detection control electrode (23) based on the demodulated detection signal. The plurality of diagnostic circuits (6) includes a third diagnostic circuit (63) having an input terminal (633) connected to an electric path between the detection feedback circuit (43) and the detection control electrode (23). The switching frequency, which is the reciprocal of the period in which the first signal appears, is a frequency outside the response range of a detection loop circuit (L1) including the vibrator (10), the conversion circuit (41), the first demodulation circuit (42), and the detection feedback circuit (43).

[0156] According to the above configuration, the test signal (T1) is attenuated by circulating through the detection loop circuit (L1). This reduces the possibility that the test signal (T1) will affect the angular velocity signal. In other words, it reduces the possibility that the test signal (T1) will interfere with the detection of the angular velocity. Furthermore, the third diagnostic circuit (63) can perform fault diagnosis of the control unit (U1) using the test signal (T1) before it is attenuated.

[0157] In addition, in the gyro sensor (1) according to the third aspect, in the first or second aspect, the test signal (T1) is a signal that periodically switches between a first signal, a second signal, a third signal whose phase is 180 degrees different from that of the drive signal (D1), and a fourth signal whose phase is 270 degrees different from that of the drive signal (D1).

[0158] According to the above configuration, the demodulated first signal (TD1), which is a demodulated signal of the first signal and the third signal, is a signal that does not include the angular velocity component of the vibrator (10). Therefore, the angular velocity component of the vibrator (10) can be easily removed and the test signal (T1) can be extracted. Moreover, the demodulated second signal (TD2), which is a demodulated signal of the second signal and the fourth signal, is a signal that does not include the quadrature signal. Therefore, the quadrature signal can be easily removed and the test signal (T1) can be extracted.

[0159] In addition, in the gyro sensor (1) according to the fourth aspect, in the third aspect, the test signal (T1) is a signal that repeatedly switches from the first signal to the second signal, from the second signal to the third signal, from the third signal to the fourth signal, and from the fourth signal to the first signal.

[0160] According to the above configuration, it is possible to reduce the possibility that a signal not used for fault diagnosis occurs in a frequency band near the test signal (T1) used for fault diagnosis in the diagnostic circuit (6).

[0161] In the gyro sensor (1) according to a fifth aspect, in any one of the first to fourth aspects, the test signal (T1) is a signal obtained by periodically switching the phase of the drive signal (D1).

[0162] According to the above configuration, the test signal (T1) can be easily generated.

[0163] The configurations other than those of the first aspect are not essential to the gyro sensor (1) and may be omitted as appropriate. [Explanation of symbols]

[0164] 1 Gyro sensor 2 electrodes 6 Diagnostic Circuit 10 Transducers 21 Drive electrode 22 Detection electrode 23 Detection control electrode 24 Quadrature Correction Electrode 31 Drive circuit 33 Detection processing circuit 34;34A Test signal generator 41 Conversion circuit 42 First demodulation circuit 43 Detection feedback circuit 51 Second demodulation circuit 53 Quadrature feedback circuit 61 First diagnostic circuit 62 Second diagnostic circuit 63 Third diagnostic circuit 344 Output terminal 513 Input terminal 613 Input terminal 623 Input terminal 633 Input terminal D1 Drive signal L1 Detection Loop Circuit S1 detection signal T1 Test Signal U1 Control section

Claims

1. A vibrator; A plurality of electrodes including a drive electrode, a detection electrode, and a quadrature correction electrode, which are arranged to face the vibrator and form a capacitance between the vibrator and the plurality of electrodes; a control unit connected to the drive electrodes, the detection electrodes, and the quadrature correction electrodes; The control unit is A drive circuit that outputs a drive signal to the drive electrode to induce drive vibration of the vibrator; a conversion circuit that converts a detection signal output from the detection electrode; a first demodulation circuit connected to a downstream of the conversion circuit, for generating a demodulated detection signal by demodulating a signal component having the same phase as the drive signal from the detection signal converted by the conversion circuit; a detection processing circuit connected to a downstream of the first demodulation circuit and configured to generate an angular velocity signal representing an angular velocity of the transducer based on the demodulated detection signal; a second demodulation circuit having an input terminal connected to an electric path between the conversion circuit and the first demodulation circuit, for generating a quadrature signal by demodulating a signal component of the detection signal converted by the conversion circuit, the signal component having a phase difference of 90 degrees with the drive signal; a quadrature feedback circuit that is inserted between the second demodulation circuit and the quadrature correction electrode and generates a voltage to be applied to the quadrature correction electrode based on the quadrature signal; a test signal generating unit having an output terminal connected to an electric path between the detection electrode and the conversion circuit, the test signal generating unit adding a test signal for fault diagnosis to the detection signal via the output terminal and outputting the test signal to the conversion circuit; a plurality of diagnostic circuits for generating a fault diagnosis signal representing a result of a fault diagnosis of the control unit based on the test signal; The plurality of diagnostic circuits include a first diagnostic circuit having an input terminal connected to an electrical path between the first demodulation circuit and the detection and processing circuit; a second diagnostic circuit having an input terminal connected to an electrical path between the second demodulation circuit and the quadrature feedback circuit; the test signal is a signal in which a first signal having the same phase as the drive signal and a second signal having a phase difference of 90 degrees from that of the drive signal are periodically switched. Gyro sensor.

2. the plurality of electrodes further includes a detection control electrode; The control unit is a detection feedback circuit that is inserted between the first demodulation circuit and the detection control electrode and generates a voltage to be applied to the detection control electrode based on the demodulated detection signal; the plurality of diagnostic circuits includes a third diagnostic circuit having an input terminal connected to an electrical path between the sensing feedback circuit and the sensing control electrode; A switching frequency, which is the inverse of the period during which the first signal appears, is a frequency outside the response range of a detection loop circuit including the vibrator, the conversion circuit, the first demodulation circuit, and the detection feedback circuit. The gyro sensor according to claim 1 .

3. the test signal is a signal in which the first signal, the second signal, a third signal having a phase difference of 180 degrees from that of the drive signal, and a fourth signal having a phase difference of 270 degrees from that of the drive signal are periodically switched. The gyro sensor according to claim 1 .

4. the test signal is a signal that repeatedly switches from the first signal to the second signal, from the second signal to the third signal, from the third signal to the fourth signal, and from the fourth signal to the first signal. The gyro sensor according to claim 3 .

5. The test signal is a signal obtained by periodically switching the phase of the drive signal. The gyro sensor according to claim 1 .

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