Gyroscope

Abstract

To provide a gyro sensor that is miniaturized and power-efficient. [Solution] The gyro sensor 1 includes a signal generation unit 35. The signal generation unit 35 includes a phase adjustment unit 351, a signal waveform generation unit 352, and an amplitude adjustment unit 353. The phase adjustment unit 351 generates a zero-point correction signal H1 from the drive signal D1 to cancel out the difference signal contained in the detection signal S1 by adjusting the phase of the drive signal D1 to the opposite phase. The signal waveform generation unit 352 generates a combined signal G1 by combining the test signal M1 and the zero-point correction signal H1. The amplitude adjustment unit 353 generates an injection signal T1 from the combined signal G1 by adjusting the amplitude of the combined signal G1.

Description

Technical Field

[0001] The present disclosure generally relates to gyro sensors, and more particularly to gyro sensors that perform fault diagnosis and zero point correction.

Background Art

[0002] Patent Document 1 describes an angular velocity sensor that performs offset correction (zero point correction) on a detected sense signal. This angular velocity sensor includes a correction circuit unit that generates a correction signal (zero point correction signal) for canceling the signal component of the sense signal that is erroneously detected as if an angular velocity is present when no angular velocity is present in the vibrator.

[0003] Also, Patent Document 2 describes a system for performing fault diagnosis of a gyroscope. This system includes a test signal generator and a test signal detector. The test signal generator injects a test signal into the rate feedback loop of the MEMS gyroscope. The test signal detector extracts and demodulates the test signal from the rate feedback loop, and monitors the operation of the gyroscope based on the demodulated test signal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] A gyroscope is desired that incorporates both the zero-point correction function described in Patent Document 1 and the fault diagnosis function described in Patent Document 2. In this case, the gyroscope would need to have separate circuits for generating the zero-point correction signal and the test signal, which would result in a larger gyroscope and increased power consumption.

[0006] This disclosure aims to provide a gyro sensor that is miniaturized and power-efficient. [Means for solving the problem]

[0007] A gyro sensor according to one aspect of the present disclosure comprises a vibrator, a plurality of electrodes, and a control unit. The plurality of electrodes include a drive electrode and a detection electrode, and are arranged to face the vibrator, forming a capacitance between them and the vibrator. The control unit is connected to the drive electrode and the detection electrode. The control unit comprises a drive circuit, a conversion circuit, a first demodulation circuit, a detection processing circuit, a zero-point output determination unit, a test signal generation unit, a signal generation unit, and a first diagnostic circuit. The drive circuit outputs a drive signal to the drive electrode, inducing drive vibration of the vibrator. The conversion circuit converts the detection signal output from the detection electrode from a current signal to a voltage signal. The first demodulation circuit is connected downstream of the conversion circuit and generates a demodulated detection signal by demodulating the signal component in phase with the drive signal from the detection signal converted by the conversion circuit. The detection processing circuit is connected downstream 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 zero-point output determination unit generates a difference signal indicating the difference between the angular velocity signal and the zero-point reference output value when no angular velocity is applied. The test signal generation unit generates a test signal. The signal generation unit generates an injection signal to be injected into the circuit between the detection electrode and the first demodulation circuit. The first diagnostic circuit is connected downstream of the conversion circuit, performs fault diagnosis of the control unit based on the injection signal, and generates a fault diagnosis signal representing the fault diagnosis result. The signal generation unit comprises a phase adjustment unit, a signal waveform generation unit, and a first amplitude adjustment unit. The phase adjustment unit generates a zero-point correction signal from the drive signal to cancel out the difference signal included in the detection signal by adjusting the phase of the drive signal to the opposite phase. The signal waveform generation unit generates a composite signal by combining the test signal and the zero-point correction signal. The first amplitude adjustment unit generates the injection signal from the composite signal by adjusting the amplitude of the composite signal. [Effects of the Invention]

[0008] This disclosure has the effect of providing a gyro sensor that is miniaturized and power-efficient. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing the circuit configuration of a gyro sensor according to Embodiment 1. [Figure 2] Figure 2 is an explanatory diagram illustrating the processing flow of the signal generation unit of the gyro sensor mentioned above. [Figure 3] Figure 3 is an explanatory diagram illustrating the waveforms of various signals used in the processing of the signal generation unit described above. [Figure 4] Figure 4 is a block diagram showing the configuration of the test signal generation unit for modified example 2 of Embodiment 1 and modified example 2 of Embodiment 2. [Figure 5] Figure 5 is an explanatory diagram illustrating the relationship between the test signal and the composite signal generated by the test signal generation unit described above. [Figure 6] Figure 6 is a graph showing the relationship between the duty cycle and amplitude ratio of the same test signal. [Figure 7] Figure 7 is a block diagram showing the configuration of the signal waveform generation unit in Modification 4 of Embodiment 1. [Figure 8] Figure 8 is an explanatory diagram illustrating the waveforms of various signals used in the processing of the signal waveform generation unit described above. [Figure 9] Figure 9 is a block diagram showing the configuration of the signal waveform generation unit in Modification 5 of Embodiment 1. [Figure 10] Figure 10 is an explanatory diagram illustrating the waveforms of various signals used in the processing of the signal waveform generation unit described above. [Figure 11] Figure 11 is a block diagram showing the configuration of the signal waveform generation unit in a modified example 6 of Embodiment 1. [Figure 12] Figure 12 is an explanatory diagram illustrating the composite signal when the difference signal is not zero. [Figure 13] Figure 13 is an explanatory diagram illustrating the composite signal when the difference signal is zero. [Figure 14] Figure 14 is a block diagram showing the circuit configuration of a gyro sensor according to Embodiment 2. [Figure 15]FIG. 15 is a block diagram showing the configuration of the signal generation unit of the gyro sensor described above. [Figure 16] FIG. 16 is an explanatory diagram for explaining the waveforms of various signals used in the processing of the signal generation unit of the gyro sensor described above and the waveform of the demodulation test signal. [Figure 17] FIG. 17 is an explanatory diagram for explaining the waveforms of various signals used in the processing of the signal generation unit of Modification 1 of Embodiment 2 and the waveform of the demodulation test signal.

MODE FOR CARRYING OUT THE INVENTION

[0010] (Embodiment 1) Hereinafter, the gyro sensor 1 according to Embodiment 1 will be described with reference to the drawings. However, the following embodiment is only one of various embodiments of the present disclosure. The following embodiment can be variously modified according to design and the like as long as the object of the present disclosure can be achieved. In addition, each drawing described in the following embodiment is a schematic diagram, and the ratio of the size and thickness of each component in the drawing does not necessarily reflect the actual dimensional ratio.

[0011] (Overview) As shown in Figure 1, the gyro sensor 1 of Embodiment 1 comprises an oscillator 10, a plurality of electrodes 2, and a control unit U1. The plurality of electrodes 2 include a drive electrode 21 and a detection electrode 22, and are arranged to face the oscillator 10, forming capacitance between them and the oscillator 10. The control unit U1 is connected to the drive electrode 21 and the detection electrode 22. The control unit U1 comprises a drive circuit 31, a conversion circuit 41, a first demodulation circuit 42, a detection processing circuit 33, a zero-point output determination unit 36, a test signal generation unit 34, a signal generation unit 35, and a diagnostic circuit 61 (first diagnostic circuit). The drive circuit 31 outputs a drive signal D1 to the drive electrode 21, inducing drive vibration of the oscillator 10. The conversion circuit 41 converts the detection signal S1 output from the detection electrode 22 from a current signal to a voltage signal. The first demodulation circuit 42 is connected downstream of the conversion circuit 41 and generates a demodulated detection signal by demodulating the 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 downstream of the first demodulation circuit 42 and generates an angular velocity signal representing the angular velocity of the oscillator 10 based on the demodulated detection signal. The zero-point output determination unit 36 ​​generates a difference signal representing the difference between the angular velocity signal when no angular velocity is applied and the zero-point reference output value. The test signal generation unit 34 generates a test signal M1. The signal generation unit 35 generates an injection signal T1 to be injected into the circuit between the detection electrode 22 and the first demodulation circuit 42. The diagnostic circuit 61 is connected downstream of the conversion circuit 41 and performs fault diagnosis of the control unit U1 based on the injection signal T1a and generates a fault diagnosis signal representing the fault diagnosis result. The signal generation unit 35 includes a phase adjustment unit 351, a signal waveform generation unit 352, and an amplitude adjustment unit 353 (first amplitude adjustment unit). The phase adjustment unit 351 generates a zero-point correction signal H1 from the drive signal D1 to cancel out the difference signal contained in the detection signal S1 by adjusting the phase of the drive signal D1 to the opposite phase. The signal waveform generation unit 352 generates a combined signal G1 by combining the test signal M1 and the zero-point correction signal H1. The amplitude adjustment unit 353 generates an injection signal T1 from the combined signal G1 by adjusting the amplitude of the combined signal G1.

[0012] According to this configuration, the signal generation unit 35 can generate both the zero point correction signal H1 (i.e., the reverse drive signal D2) and the injection test signal (the test signal M1 synthesized with the reverse drive signal D2). As a result, compared with the case where the signal generation circuit for the zero point correction signal and the signal generation circuit for the injection test signal are configured separately, duplication of processing circuits (such as the phase adjustment unit 351 and the amplitude adjustment unit 353) having the same function between those signal generation circuits can be reduced. Consequently, the gyro sensor 1 can be miniaturized and power consumption can be reduced.

[0013] (Details) Referring to FIGS. 1 to 13, the gyro sensor 1 of Embodiment 1 will be described in more detail. Note that the waveforms of various signals shown in FIGS. 3, 5, 8, 10, 12, and 14 show the time change of the amplitude of the above signals. Although the vertical axis and the horizontal axis are not shown, the vertical axis is the amplitude and the horizontal axis is the time axis.

[0014] (1) Overall Configuration As shown in FIG. 1, the gyro sensor 1 includes a vibrator 10, a plurality (eight in FIG. 1) of electrodes 2, and a control unit U1.

[0015] The plurality of electrodes 2 includes two drive electrodes 21, two detection electrodes 22, and two detection control electrodes 23.

[0016] 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 zero point output determination unit 36, a signal generation unit 35, and a plurality (two in FIG. 1) of diagnostic circuits 6 (diagnostic circuit 61 and diagnostic circuit 63). <00001 and 10>

[0017] In the gyro sensor 1, among the detection signals S1 output from the detection electrodes 22, the signal having the same phase as the drive signal D1 is fed back to the vibrator 10 through the detection loop circuit L1. The detection loop circuit L1 includes the vibrator 10, the conversion circuit 41, the first demodulation circuit 42, and the detection feedback circuit 43.

[0018] (2) Vibrator and multiple electrodes The oscillator 10 is formed from a material including, for example, single-crystal silicon or polycrystalline silicon. The shape of the oscillator 10 is, for example, a disc shape.

[0019] Multiple electrodes 2 are arranged around the oscillator 10, spaced apart from the oscillator 10. Each of the multiple electrodes 2 has a facing surface that faces the oscillator 10.

[0020] It is preferable that the multiple electrodes 2 correspond one-to-one so that they form pairs. The multiple electrodes 2 in this embodiment include two corresponding drive electrodes 21, two corresponding detection electrodes 22, and two corresponding detection control electrodes 23.

[0021] In Figure 1, two corresponding electrodes 2 are shown adjacent to each other, but it is preferable that the two corresponding electrodes 2 are positioned on opposite sides of the oscillator 10 with respect to its center. In other words, it is preferable that the oscillator 10 is positioned between the two corresponding electrodes 2.

[0022] (3) Drive circuit As shown in Figure 1, the drive circuit 31 is connected to 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. The waveform of the drive signal D1 is, for example, a sine wave. The drive circuit 31 outputs drive signals D1 to the two drive electrodes 21 that are out of phase (opposite phase) to each other.

[0023] When a drive signal D1 is output to at least one drive electrode 21, the oscillator 10 vibrates (expands and contracts) periodically due to the electrostatic force between the oscillator 10 and at least one drive electrode 21. This vibration is referred to as drive vibration in this disclosure.

[0024] The frequency of the drive signal D1 is, for example, between 1 MHz and 10 MHz.

[0025] (4) Conversion circuit When the oscillator 10 rotates, it resonates due to the Coriolis force. As a result, the distance between the oscillator 10 and the two detection electrodes 22 changes according to the angular velocity of the oscillator 10, and therefore the capacitance between the oscillator 10 and the two detection electrodes 22 also changes. The two detection electrodes 22 output a detection signal S1 corresponding to the magnitude of the capacitance. The detection signal S1 is a signal corresponding to the magnitude of the angular velocity of the oscillator 10.

[0026] 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 being perfectly equal, but also includes cases where they differ within a range that does not pose a practical problem. For example, if the difference between the frequency of the detection signal S1 and the frequency of the drive signal D1 is within 0.2% or less of either value, the frequencies of the detection signal S1 and the drive signal D1 may be considered "equal" and the disclosure may be applied accordingly.

[0027] As shown in Figure 1, 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 can be, for example, a circuit that performs CV conversion (conversion from capacitance to voltage) or IV conversion (conversion from current to voltage) on the detection signal S1. In this embodiment, the conversion circuit 41 includes a transimpedance amplifier 411 and performs IV conversion on the detection signal S1.

[0028] A signal generation unit 35 is connected to the circuit between the two detection electrodes 22 and the first demodulation circuit 42 (more specifically, the circuit between the two detection electrodes 22 and the conversion circuit 41). The signal ST1 input to the conversion circuit 41 is the sum of the detection signal S1 output from each of the two detection electrodes 22 and the injection signal T1 output from the signal generation unit 35. The injection signal T1 includes a test signal M1 and a zero-point correction signal H1. The test signal M1 is a signal used for fault diagnosis of the control unit U1. The zero-point correction signal H1 is a signal used to cancel out the difference signal included in the detection signal S1. The difference signal is a signal that represents the difference between the angular velocity signal when no angular velocity is applied and a predetermined zero-point reference output value, and is also called the zero-point signal. In the following explanation, the difference signal (zero-point signal) is adjusted by the amplitude adjustment unit 353, but for the sake of explanation, it will be described as a signal with the same phase (e.g., 0 degrees) and amplitude as the drive signal D1. The zero-point correction signal H1 is the same signal as the inverse-phase drive signal D2, which is obtained by adjusting the phase of the drive signal D1 to the opposite phase. The injection signal T1 is constructed by superimposing the test signal M1 onto the zero-point correction signal H1 (inverse-phase drive signal D2). By combining the injection signal T1 with the difference signal included in the detection signal S1, the injection signal T1 is converted into an injection signal T1a, which is a signal in which the test signal M1 is superimposed on the drive signal D1. Furthermore, through this conversion, the detection signal S1 becomes the detection signal S1a, in which the difference signal is canceled out. That is, the conversion circuit 41 receives a signal ST1, which includes the detection signal S1a with the difference signal canceled out and the combined injection signal T1a. The conversion circuit 41 converts signal ST1 from a current signal to a voltage signal and outputs it as signal ST2.

[0029] Since the conversion circuit 41 includes a transimpedance amplifier 411, the connection between the signal generation unit 35 and the conversion circuit 41 can be made simple. Specifically, without using an adder, the detection signal S1 and the signal generation unit 35 can be added simply by connecting the detection electrode 22 and the output terminal 355 of the signal generation unit 35.

[0030] (5) Test signal generation unit As shown in Figure 1, the test signal generation unit 34 generates a test signal M1 and inputs it to the signal generation unit 35. The test signal M1 is, for example, a square wave. The frequency of the test signal M1 is, for example, between 10 kHz and 100 kHz. The test signal generation unit 34 includes, for example, an oscillator that generates the test signal M1.

[0031] (6) Signal generation unit As shown in Figure 1, the signal generation unit 35 generates an injection signal T1 and outputs it to the conversion circuit 41. The signal generation unit 35 includes a phase adjustment unit 351, a signal waveform generation unit 352, an amplitude adjustment unit 353, two voltage-current conversion units 354, and two output terminals 355.

[0032] The phase adjustment unit 351 receives the drive signal D1 output from the drive circuit 31 and generates an inverse phase drive signal D2 by adjusting the phase of the input drive signal D1 by 180 degrees. The inverse phase drive signal D2 becomes the zero-point correction signal H1. Note that the drive signal D1 is two differential signals with a phase difference of 180 degrees from each other. Therefore, the inverse phase drive signal D2 is also two differential signals with a phase difference of 180 degrees from each other.

[0033] The signal waveform generation unit 352 generates a composite signal G1 by combining the test signal M1 from the test signal generation unit 34 and the inverse phase drive signal D2 (i.e., zero-point correction signal H1) generated by the phase adjustment unit 351. The signal waveform generation unit 352 includes a modulation circuit 70. The modulation circuit 70 modulates (e.g., on / off control) the inverse phase drive signal D2 (i.e., zero-point correction signal H1) based on the test signal M1, thereby superimposing the test signal M1 onto the inverse phase drive signal D2 (i.e., zero-point correction signal H1). In other words, the modulation circuit 70 generates a composite signal G1 by superimposing the test signal M1 onto the inverse phase drive signal D2 (zero-point correction signal H1) through modulation, thereby combining the test signal M1 and the zero-point correction signal H1. The signal waveform generation unit 352 outputs the composite signal G1 to the amplitude adjustment unit 353.

[0034] The amplitude adjustment unit 353 generates the injection signal T1 from the synthesized signal G1 by adjusting the amplitude of the synthesized signal G1 generated by the signal waveform generation unit 352.

[0035] The voltage-current conversion unit 354 converts the injection signal T1 generated by the amplitude adjustment unit 353 from a voltage signal to a current signal (also called VI conversion). The voltage-current conversion unit 354 injects the VI-converted injection signal T1 into the circuit between the two detection electrodes 22 and the conversion circuit 41.

[0036] (7) Processing flow in the signal generation unit Referring to Figures 2 and 3, the processing flow in the signal generation unit 35 (i.e., the processing flow from the drive signal D1 to the formation of the synthesized injection signal T1a) will be explained.

[0037] The phase adjustment unit 351 shifts the phase of the drive signal D1 by 180 degrees, thereby generating a zero-point correction signal H1, which is an inverse-phase drive signal D2, from the drive signal D1 (see the waveform of D2 in Figure 3). Although the drive signal D1 is paired with a drive signal D1 with the opposite phase, for the sake of explanation, the following description will focus on the drive signal D1 with a phase of 0 degrees. In this case, the inverse-phase drive signal D2 will have a phase of 180 degrees.

[0038] The signal waveform generation unit 352 then uses the test signal M1 from the test signal generation unit 34 (see the waveform of M1 in Figure 3) to modulate (for example, by on / off control) the zero-point correction signal H1 generated by the phase adjustment unit 351, thereby generating a combined signal G1 (see the waveform of G1 in Figure 3) which is a combination of the zero-point correction signal H1 and the test signal M1. In this generation, the signal waveform generation unit 352 superimposes the test signal M1 onto the zero-point correction signal H1 to combine the zero-point correction signal H1 and the test signal M1. More specifically, the signal waveform generation unit 352 receives the zero-point correction signal H1 from the phase adjustment unit 351, outputs the input zero-point correction signal H1 during the high-level section of the test signal M1, and stops outputting the input zero-point correction signal H1 during the low-level section of the test signal M1. As a result, the signal waveform generation unit 352 generates a composite signal G1 that has the same amplitude and phase (180 degrees) as the zero-point correction signal H1 in the high-level section of the test signal M1, and has zero amplitude in the low-level section of the test signal M1. The signal waveform generation unit 352 then outputs the generated composite signal G1 to the amplitude adjustment unit 353.

[0039] The amplitude adjustment unit 353 then adjusts the amplitude of the composite signal G1 generated by the signal waveform generation unit 352 to, for example, an integer multiple (for example, 2 times), thereby generating an injection signal T1 (see the waveform of T1 in Figure 3) from the composite signal G1. The injection signal T1 has the same phase and amplitude as the zero-point correction signal H1 and twice the amplitude in the high-level section of the test signal M1, and has zero amplitude in the low-level section of the test signal M1. The amplitude adjustment unit 353 then outputs the amplitude-modulated injection signal T1 to the voltage-current conversion unit 354.

[0040] The voltage-to-current conversion unit 354 then converts the injection signal T1, whose amplitude has been adjusted by the amplitude adjustment unit 353, from a voltage signal to a current signal and injects it into a predetermined circuit between the two detection electrodes 22 and the conversion circuit 41 (i.e., the input terminal of the conversion circuit 41).

[0041] When the injected signal T1 is injected into the circuit between the two detection electrodes 22 (see Figure 1) and the conversion circuit 41 (see Figure 1), it is combined with the difference signal (zero-point signal S0, see the waveform of S0 in Figure 3) contained in the detection signal S1 output from the two detection electrodes 22. This combination cancels out the difference signal (zero-point signal S0) contained in the detection signal S1. Furthermore, through the above combination, the injected signal T1 is converted into an injected signal T1a. The combined injected signal T1a is a signal in which the test signal M1 is superimposed on a drive signal D1 (carrier wave) with a phase of 0 degrees. More specifically, the synthesized injected signal T1a has the same amplitude and phase (180 degrees) as the zero-point correction signal H1 in the high-level section of the test signal M1, and the same amplitude and phase (0 degrees) as the drive signal D1 in the low-level section of the test signal M1 (see the waveform of T1a in Figure 3). In this way, by converting the injected signal T1 to the injected signal T1a, the test signal M1 contained in the injected signal T1a can be demodulated by the first demodulation circuit 42 and reach the diagnostic circuit 61 and the diagnostic circuit 63.

[0042] (8) First demodulation circuit As shown in Figure 1, the input terminal of the first demodulation circuit 42 is connected to the 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 the signal component of the signal ST2 output from the conversion circuit 41 that is in phase with the drive signal D1.

[0043] The demodulated signal ST3 includes a "demodulation detection signal" and a "demodulation test signal". The demodulation detection signal is the signal obtained by demodulating the signal component in phase with the drive signal D1 from the detection signal S1a. The demodulation test signal is the test signal M1 obtained by demodulating the signal component in phase with the drive signal D1 from the injection signal T1a.

[0044] In the following, the "demodulation detection signal" may be referred to as detection signal S1a, and the "demodulation test signal" may be referred to as test signal M1. When the gyro sensor 1 is operating normally, the detection signal S1a and test signal M1 included in signal ST2 are in phase with the drive signal D1, so these detection signals S1a and test signals M1 match the detection signals S1a and test signals M1 included in demodulation signal ST3. If there is a problem with the gyro sensor 1 and signal ST2 contains a signal with a different phase from the drive signal D1, the detection signals S1a and test signals M1 included in signal ST2 will no longer match the detection signals S1a and test signals M1 included in demodulation signal ST3. In the following, when it is necessary to clarify which detection signal S1a or test signal M1 is being referred to, the source from which the detection signal S1a or test signal M1 was output is indicated.

[0045] (9) First connection circuit As shown in Figure 1, 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.

[0046] The input terminal of the VI converter 321 is connected to the output terminal of the first demodulation circuit 42. The output terminal of the VI converter 321 is connected to the analog input terminal of the AD converter 322.

[0047] The demodulated signal ST3 output from the first demodulation circuit 42 is converted into a current signal by the VI converter 321 and then converted into a digital signal by the AD converter 322.

[0048] (10) Detection processing circuit As shown in Figure 1, the input terminal of the detection processing circuit 33 is connected to the digital output terminal of the AD converter 322. The detection processing circuit 33 generates an angular velocity signal representing the angular velocity of the oscillator 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 form, which is input to the detection processing circuit 33. The demodulated signal ST3 includes a signal obtained by demodulating the test signal M1 (demodulated test signal) and a signal obtained by demodulating the detection signal S1a (demodulated detection signal). The signal obtained by demodulating the detection signal S1a is a signal corresponding to the magnitude of the angular velocity of the oscillator 10, and corresponds to the angular velocity signal.

[0049] The detection processing circuit 33 generates an angular velocity signal by removing the test signal M1 component from the digital signal output from the first connection circuit 32 using a low-pass filter or the like, and extracting the angular velocity signal component.

[0050] (11) Zero point output determination unit The zero-point output determination unit 36 ​​generates a difference signal (zero-point signal) and outputs it to the signal waveform generation unit 352 of the signal generation unit 35. More specifically, the zero-point output determination unit 36 ​​generates a difference signal indicating the calculation result by calculating the difference between the angular velocity signal generated by the detection processing circuit 33 when angular velocity is not applied to the oscillator 10 and a predetermined zero-point reference output value. The zero-point reference output value is stored in advance, for example, a predetermined storage unit of the zero-point output determination unit 36. The zero-point output determination unit 36 ​​outputs the generated difference signal to the signal generation unit 35. The signal generation unit 35 receives the difference signal from the zero-point output determination unit 36 ​​and generates a composite signal G1 including a zero-point correction signal H1 to cancel out the difference signal. In Embodiment 1, it is assumed that the difference signal is not zero. That is, in Embodiment 1, it is assumed that the zero-point correction signal H1 is needed to cancel out the difference signal (zero-point signal S0) included in the detection signal S1.

[0051] (12) Diagnostic circuit 61 As shown in Figure 1, the diagnostic circuit 61 includes a bandpass filter 611 and a comparator 612.

[0052] The input terminal of the bandpass filter 611 is connected to the 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 test signal M1 from the demodulated signal ST3.

[0053] The comparator 612 evaluates the amplitude of the test signal M1 extracted by the bandpass filter 611. Specifically, the comparator 612 determines whether the amplitude is within a predetermined threshold range. If the amplitude is within the predetermined threshold range, the comparator 612 outputs a first signal; if the amplitude is outside the predetermined threshold range, the comparator 612 outputs a second signal. The first signal indicates that the circuit from the test signal generation unit 34 to the diagnostic circuit 61 is in a normal state. The second signal indicates that the circuit from the test signal generation unit 34 to the diagnostic circuit 61 is in an abnormal state.

[0054] The circuit from the test signal generation unit 34 to the diagnostic circuit 61 includes the test signal generation unit 34, the signal generation unit 35, the conversion circuit 41, the first demodulation circuit 42, the first connection circuit 32, and the diagnostic circuit 61. In other words, the diagnostic circuit 61 uses the test signal M1 to determine whether or not there are any abnormalities in these circuits.

[0055] The comparator 612 outputs the determination result (first signal or second signal) to, for example, a predetermined storage device. The predetermined storage device stores the determination result. The predetermined storage device stores the determination result together with, for example, information about the time the determination was made.

[0056] (13) Detection feedback circuit As shown in Figure 1, 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 output terminal of the detection feedback circuit 43 are connected to the first demodulation circuit 42 and the detection control electrode 23, respectively.

[0057] The demodulated signal ST3 output from the first demodulation circuit 42 is input to the detection feedback circuit 43. Based on the demodulated signal ST3, the detection feedback circuit 43 generates voltages to be applied to the two detection control electrodes 23.

[0058] The chopper circuit 431, when used in conjunction with circuit 433, reduces the 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, which is output from the chopper circuit 431 as a voltage signal, into a current signal. Circuit 433 includes a modulator that AM modulates (amplitude modulates) the demodulated signal ST3 with a drive signal D1 as a carrier wave. The transimpedance amplifier 434 converts the demodulated signal ST3, which has been modulated by the drive signal D1, from a current signal into a voltage signal.

[0059] The output terminals of the transimpedance amplifier 434 are connected to two detection control electrodes 23. Additionally, the output terminals of the transimpedance amplifier 434 are connected to a diagnostic circuit 63.

[0060] When a voltage is applied from the detection feedback circuit 43 to the two detection control electrodes 23, the amplitude of the resonant vibration of the oscillator 10, which corresponds to the angular velocity of the oscillator 10, decreases. As a result, the amplitude of the detection signal S1 becomes smaller relative to the magnitude of the angular velocity of the oscillator 10. Therefore, the gyro sensor 1 becomes capable of detecting larger angular velocities. In other words, the dynamic range of the gyro sensor 1 is widened.

[0061] (14) Diagnostic circuit 63 As shown in Figure 1, the diagnostic circuit 63 includes a demodulation circuit 634, a low-pass filter 631, and a comparator 632.

[0062] The 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 using the drive signal D1.

[0063] The input terminal of the low-pass filter 631 is connected to the output terminal of the demodulation circuit 634. The low-pass filter 631 extracts the test signal M1 from the signal demodulated by the demodulation circuit 634.

[0064] The comparator 632 evaluates the amplitude of the test signal M1 extracted by the low-pass filter 631. Specifically, the comparator 632 determines whether the amplitude is within a predetermined threshold range. If the amplitude is within the predetermined threshold range, the comparator 632 outputs a first signal; if the amplitude is outside the predetermined threshold range, the comparator 632 outputs a second signal. The first signal indicates that the circuit from the test signal generation unit 34 to the diagnostic circuit 63 is in a normal state. The second signal indicates that the circuit from the test signal generation unit 34 to the diagnostic circuit 63 is in an abnormal state. For example, if the gain of the circuit is abnormal, the comparator 632 outputs a second signal.

[0065] The circuit from the test signal generation unit 34 to the diagnostic circuit 63 includes the test signal generation unit 34, the signal generation unit 35, the conversion circuit 41, the first demodulation circuit 42, the detection feedback circuit 43, and the diagnostic circuit 63. In other words, the diagnostic circuit 63 uses the test signal M1 to determine whether or not there is an abnormality in these circuits.

[0066] The comparator 632 outputs the determination result (first signal or second signal) to, for example, a predetermined storage device. The predetermined storage device stores the determination result. The predetermined storage device stores the determination result together with, for example, information about the time the determination was made.

[0067] (15) Location to connect the diagnostic circuit As shown in Figure 1, the two diagnostic circuits 6 (diagnostic circuit 61 and diagnostic circuit 63) are each connected to the downstream (output side) of the conversion circuit 41. Specifically, the downstream of the first demodulation circuit 42 includes the following first and second circuits. The first circuit is the circuit 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 circuit is the circuit from the conversion circuit 41 to the two detection control electrodes 23 via the first demodulation circuit 42 and the detection feedback circuit 43.

[0068] The diagnostic circuit 61 has two input terminals 613 connected to the circuit between the first demodulation circuit 42 and the detection processing circuit 33.

[0069] The diagnostic circuit 63 has an input terminal 633 connected to the circuit between the detection feedback circuit 43 and the two detection control electrodes 23.

[0070] Diagnostic circuits 61 and 63 generate fault diagnosis signals representing the results of fault diagnosis by the control unit U1 based on the test signal M1. The first and second signals described above are examples of fault diagnosis signals.

[0071] (16) Effects The gyro sensor 1 according to Embodiment 1 comprises an oscillator 10, a plurality of electrodes 2, and a control unit U1. The plurality of electrodes 2 include a drive electrode 21 and a detection electrode 22, and are arranged to face the oscillator 10, forming capacitance between them and the oscillator 10. The control unit U1 is connected to the drive electrode 21 and the detection electrode 22. The control unit U1 comprises a drive circuit 31, a conversion circuit 41, a first demodulation circuit 42, a detection processing circuit 33, a zero-point output determination unit 36, a test signal generation unit 34, a signal generation unit 35, and a diagnostic circuit 61. The drive circuit 31 outputs a drive signal D1 to the drive electrode 21, inducing drive vibration of the oscillator 10. The conversion circuit 41 converts the detection signal S1 output from the detection electrode 22 from a current signal to a voltage signal. The first demodulation circuit 42 is connected downstream of the conversion circuit 41 and generates a demodulated detection signal by demodulating the 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 downstream of the first demodulation circuit 42 and generates an angular velocity signal representing the angular velocity of the oscillator 10 based on the demodulated detection signal. The zero-point output determination unit 36 ​​generates a difference signal showing the difference between the angular velocity signal when no angular velocity is applied and the zero-point reference output value. The test signal generation unit 34 generates a test signal M1. The signal generation unit 35 generates an injection signal T1 to be injected into the circuit between the detection electrode 22 and the first demodulation circuit 42. The diagnostic circuit 61 is connected downstream of the conversion circuit 41 and performs fault diagnosis of the control unit U1 based on the injection signal T1 and generates a fault diagnosis signal representing the fault diagnosis result. The signal generation unit 35 includes a phase adjustment unit 351, signal waveform generation units 352, 352A to 352D, and an amplitude adjustment unit 353. The phase adjustment unit 351 generates a zero-point correction signal H1 from the drive signal D1 to cancel out the difference signal contained in the detection signal S1 by adjusting the phase of the drive signal D1 to the opposite phase. The signal waveform generation units 352, 352A to 352D combine the test signal M1 and the zero-point correction signal H1 to generate a combined signal G1. The amplitude adjustment unit 353 generates an injection signal T1 from the combined signal G1 by adjusting the amplitude of the combined signal G1.

[0072] With this configuration, the signal generation unit 35 can generate both the zero-point correction signal H1 [i.e., the inverse-phase drive signal D2] and the injection test signal [the test signal M1, which is a combination of the inverse-phase drive signal D2]. This reduces the duplication of processing circuits with the same function [such as the phase adjustment unit 351 and the amplitude adjustment unit 353] between the signal generation circuits, compared to the case where the signal generation circuit for the zero-point correction signal and the signal generation circuit for the injection test signal are configured separately. As a result, the gyro sensor 1 can be made smaller and more power-efficient.

[0073] Furthermore, in the gyro sensor 1 according to Embodiment 1, the signal waveform generation unit 352 generates a composite signal G1 by controlling the output of the zero-point correction signal H1 generated by the phase adjustment unit 351 on and off based on the amplitude of the test signal M1.

[0074] With this configuration, the signal waveform generation unit 352 can be implemented with a simple configuration.

[0075] Furthermore, in the gyro sensor 1 according to Embodiment 1, the injection signal T1 is combined with the difference signal included in the detection signal S1 output from the detection electrode 22 to convert it into an injection signal T1a in which the test signal M1 is superimposed on the drive signal D1.

[0076] This configuration allows the injected signal T1 to cancel out the difference signal within the detection signal S1. Furthermore, the combined injected signal T1a can enable the test signal M1 to reach the diagnostic circuit.

[0077] (17) Variant The following are examples of modifications of Embodiment 1. These modifications may be implemented by combining them as appropriate.

[0078] (17-1) Variation 1 In Embodiment 1, the signal generation unit 35 is shown as being connected to the circuit between the two detection electrodes 22 and the conversion circuit 41. However, the signal generation unit 35 may also be connected to the circuit between the conversion circuit 41 and the first demodulation circuit 42. In this case, the voltage-current conversion unit 354 of the signal generation unit 35 is omitted. That is, in the signal generation unit 35, the injection signal T1 generated by the amplitude adjustment unit 353 is injected into the circuit between the conversion circuit 41 and the first demodulation circuit 42 without going through the voltage-current conversion unit 354. In this case as well, it is possible to achieve the same effects as in Embodiment 1.

[0079] (17-2) Variation 2 As shown in Figure 4, Modified Example 2 is configured similarly to Embodiment 1, except that the test signal generation unit 34 includes a duty cycle adjustment unit 341. The duty cycle adjustment unit 341 adjusts the duty cycle of the test signal M1 generated by the test signal generation unit 34 (i.e., the test signal M1 input to the signal generation unit 25).

[0080] As shown in Figure 5, the test signal M1 has a high-level period TH and a low-level period TL. The high-level period TH is the period during which the test signal M1 is at a high level. The low-level period TL is the period during which the test signal M1 is at a low level. The period Ts of the test signal M1 is the sum of the high-level period TH and the low-level period TL. The duty cycle of the test signal M1 is the ratio of the high-level period TH to the period Ts of the test signal M1 (=TH / Ts).

[0081] The duty cycle adjustment in the duty adjustment unit 341 can be performed, for example, by manual setting.

[0082] Increasing the duty cycle of the test signal M1 lengthens the section N1 of the composite signal G1, and decreasing the duty cycle of the test signal M1 shortens the section N1 of the composite signal G1. Section N1 of the composite signal G1 corresponds to the high-level period TH of the test signal M1 and has the same amplitude and phase as the zero-point correction signal H1. In this way, by adjusting the duty cycle of the test signal M1, it is possible to adjust the length of section N1 of the composite signal G1, and by adjusting the length of section N1, it is possible to adjust the signal amount (amplitude) of the test signal M1 and the signal amount (amplitude) of the zero-point correction signal included in the composite signal G1.

[0083] The amplitude of the zero-point correction signal H1 included in the composite signal G1 is proportional to the duty cycle of the test signal M1. That is, the amplitude of the zero-point correction signal H1 increases as the duty cycle of the test signal M1 increases, and decreases as the duty cycle of the test signal M1 decreases. Therefore, by adjusting the duty cycle of the test signal M1, it is possible to adjust the amplitude of the zero-point correction signal H1 included in the composite signal G1 and the amplitude of the test signal. Note that the amplitude of the zero-point correction signal H1 is the amplitude when the zero-point correction signal H1 is viewed in frequency space (i.e., space where the horizontal axis is frequency and the vertical axis is amplitude). The amplitude of the test signal M1 is the amplitude when the test signal M1 is viewed in frequency space (i.e., space where the horizontal axis is frequency and the vertical axis is amplitude).

[0084] Furthermore, as shown in Figure 6, the amplitude ratio of the zero-point correction signal H1 and the test signal M1 included in the composite signal G1 (more specifically, the ratio of the amplitude of the test signal M1 to the amplitude of the zero-point correction signal H1) is almost linearly inversely proportional. That is, increasing the duty cycle of the test signal M1 decreases the amplitude ratio, and decreasing the duty cycle of the test signal M1 increases the amplitude ratio. Thus, it is possible to adjust the above amplitude ratio of the composite signal G1 by adjusting the duty cycle of the test signal M1. Note that the above amplitude ratio is the ratio of the amplitude of the test signal M1 to the amplitude of the zero-point correction signal H1 when the zero-point correction signal H1 and the test signal M1 are viewed in frequency space (i.e., space where the horizontal axis is frequency and the vertical axis is amplitude).

[0085] In this way, by adjusting the duty cycle of the test signal M1, the amplitude of the zero-point correction signal H1 in the composite signal G1 can be made relatively larger than the amplitude of the test signal M1. This reduces the amplitude of the test signal M1 included in the injected signal T1. As a result, for example, the narrowing of the detection range of the detection processing circuit 33 by the test signal M1 can be reduced.

[0086] Based on the above, in the modified gyro sensor 1 according to the 2nd modification, the test signal generation unit 34 includes a duty cycle adjustment unit 341 that adjusts the duty cycle of the test signal M1. With this configuration, by adjusting the duty cycle of the test signal M1, the ratio of the signal amounts [i.e., the amplitude ratio] between the zero-point correction signal H1 included in the composite signal G1 and the test signal M1 can be adjusted.

[0087] (17-3) Modification 3 In Modification 3, similar to Embodiment 1, the signal waveform generation unit 352 controls the output of the zero-point correction signal H1 on and off according to the high-level and low-level periods of the test signal M1. In Modification 3, the configuration is the same as in Embodiment 1, except that the high-level and low-level periods of the test signal M1 are integer multiples of the period of the drive signal D1. With this configuration, when the signal waveform generation unit 352 generates a composite signal G1 by controlling the output of the zero-point correction signal H1 on and off based on the test signal M1, it is possible to reduce the inclusion of zero-point correction signals H1 that are cut off in the middle of one period in the composite signal G1. As a result, zero-point correction by the zero-point correction signal H1 (i.e., cancellation of the difference signal (zero-point signal) in the detection signal S1) can be performed with high accuracy.

[0088] (17-4) Modification 4 As shown in Figure 7, Modification 4 is configured similarly to Embodiment 1, except that the configuration of the signal waveform generation unit 352A is different.

[0089] The signal waveform generation unit 352A of the modified example 4 differs from the signal waveform generation unit 352 of Embodiment 1 in that it further includes an adder 71. That is, the signal waveform generation unit 352A includes a modulation circuit 70 and an adder 71.

[0090] The modulation circuit 70, similar to the modulation circuit 70 of Embodiment 1, generates an output signal W1 (see Figure 8) by modulating (e.g., chopper control) the zero-point correction signal H1 (i.e., the inverse-phase drive signal D2) generated by the phase adjustment unit 351 based on the test signal M1 (see Figure 8). The output signal W1 is the output signal of the modulation circuit 70, and is a signal obtained by superimposing the test signal M1 on the inverse-phase drive signal D2. During the high-level period of the test signal M1, the output signal W1 has the same amplitude (i.e., the same amplitude as the drive signal D1) and the same phase (i.e., 180 degrees) as the zero-point correction signal H1, and during the low-level period of the test signal M1, it has the same amplitude and the same phase (i.e., 0 degrees) as the drive signal D1 (see Figure 8).

[0091] The adder 71 adds the zero-point correction signal H1 generated by the phase adjustment unit 351 and the output signal W1 of the modulation circuit 70 to generate a composite signal G1. The zero-point correction signal H1 is a signal that has the same phase (i.e., 0 degrees) and amplitude (i.e., the same amplitude as the drive signal D1) as the inverse-phase drive signal D2 during the high-level and low-level periods of the test signal M1 (see Figure 8). Therefore, the composite signal G1 has the same phase (180 degrees) and twice the amplitude as the zero-point correction signal H1 during the high-level period of the test signal M1, and zero amplitude during the low-level period of the test signal M1 (see Figure 8).

[0092] The amplitude adjustment unit 353 generates an injection signal T1 by adjusting the amplitude of the composite signal G1 to, for example, 1x, and outputs it to the voltage-current conversion unit 354. In this case, since the amplitude adjustment ratio in the amplitude adjustment unit 353 is 1x based on the amplitude of the difference signal, the injection signal T1 is the same signal as the composite signal G1 (see Figure 8).

[0093] The voltage-to-current conversion unit 354 converts the amplitude-adjusted injection signal T1 from a voltage signal to a current signal and injects it into the circuit between the two detection electrodes 22 and the conversion circuit 41. In other words, in the modified example 4 as well, the same injection signal T1 as in Embodiment 1 (see the waveform of T1 in Figure 3) is injected into the circuit. Therefore, the processing after injection of the injection signal T1 is the same as in Embodiment 1.

[0094] Based on the above, in the modified gyro sensor 1 according to Modification 4, the signal waveform generation unit 352A includes a modulation circuit 70 and an adder 71. The modulation circuit 70 modulates the zero-point correction signal H1 generated by the phase adjustment unit 351 based on the test signal M1. The adder 71 adds the zero-point correction signal H1 generated by the phase adjustment unit 351 and the output signal W1 of the modulation circuit 70 to generate a composite signal G1. With this configuration, the signal waveform generation unit 352A can be realized with a simple configuration.

[0095] (17-5) Variation 5 As shown in Figure 9, Modification 5 is configured similarly to Modification 4, except that the signal waveform generation unit 352B further includes an amplitude adjustment circuit 72 (second amplitude adjustment unit).

[0096] The signal waveform generation unit 352B of Modified Example 5 is configured similarly to the signal waveform generation unit 352A of Modified Example 4, except that it further includes an amplitude adjustment circuit 72.

[0097] The amplitude adjustment circuit 72 is connected between the modulation circuit 70 and the adder 71. The amplitude adjustment circuit 72 adjusts (e.g., attenuates) the amplitude of the output signal W1 of the modulation circuit 70 to generate an output signal W2 (see the waveform of W2 in Figure 10) which has a smaller amplitude than the output signal W1 (for example, an amplitude that is one-tenth the amplitude of the output signal W1). Note that the output signal W1 is the same signal as the output signal W1 in Modification 4 (see the waveform of W1 in Figure 8). In Modification 5, it is assumed that the amplitude of the inverse phase drive signal D2 (i.e., the amplitude of the drive signal D1) is "1". In this case, the amplitude of the zero-point correction signal H1 is "1", the amplitude of the output signal W1 is "1", and the amplitude of the output signal W2 is "0.1".

[0098] The adder 71 adds the zero-point correction signal H1 generated by the phase adjustment unit 351 and the output signal W2 of the amplitude adjustment circuit 72 to generate a composite signal G1. The zero-point correction signal H1 is the same signal as the zero-point correction signal H1 in Modification Example 2. Therefore, during the high-level period of the test signal M1, the composite signal G1 has the same phase (180 degrees) and amplitude as the zero-point correction signal H1, and 1.1 times the amplitude. During the low-level period of the test signal M1, the composite signal G1 has the same phase (180 degrees) and amplitude as the zero-point correction signal H1, and 0.9 times the amplitude (see Figure 10). The numbers "(0.9)" and "(1.1)" written in parentheses below each period (high-level period and low-level period) of the waveform of G1 in Figure 10 indicate the amplitude of the composite signal G1 during each period.

[0099] The amplitude adjustment unit 353 generates an injection signal T1 by adjusting the amplitude of the composite signal G1 to, for example, 1x (i.e., an adjustment ratio of 1x), and outputs it to the voltage-current conversion unit 354. In this case, since the amplitude adjustment ratio in the amplitude adjustment unit 353 is 1x, the injection signal T1 is the same signal as the composite signal G1 (see Figure 10).

[0100] The voltage-to-current conversion unit 354 converts the amplitude-adjusted injection signal T1 from a voltage signal to a current signal and injects it into the circuit between the two detection electrodes 22 and the conversion circuit 41. In modified example 5, the injection signal T1 is combined with the difference signal (zero-point signal S0) contained in the detection signal S1, thereby converting the injection signal T1 into an injection signal T1a (see Figure 10). In modified example 5, the injection signal T1a has the same phase (180 degrees) and amplitude as the zero-point correction signal H1 during the high-level period of the test signal M1, and has the same phase (0 degrees) and amplitude as the zero-point signal S0 (i.e., drive signal D1) during the low-level period of the test signal M1.

[0101] In the above explanation, the example given was that the amplitude of output signal W2 is 0.1 times the amplitude of output signal W1. However, if the amplitude of output signal W2 is α times the amplitude of output signal W1, the synthesized injected signal T1 will have the same phase (180 degrees) and α times the amplitude as the zero-point correction signal H1 during the high-level period of test signal M1, and the same phase (0 degrees) and α times the amplitude as the zero-point signal S0 during the low-level period of test signal M1.

[0102] Thus, in Modification 5, the amplitude of the synthesized injected signal T1a can be adjusted by a factor of α. By setting α to a value less than 1, the amplitude of the synthesized injected signal T1a can be made even smaller. As a result, the narrowing of the detection range in the detection processing circuit 33 by the test signal M1 included in the injected signal T1a can be reduced.

[0103] Based on the above, the gyro sensor 1 according to modified example 5 further includes an amplitude adjustment circuit 72 (second amplitude adjustment unit). The amplitude adjustment circuit 72 is provided between the modulation circuit 70 and the adder 71. The amplitude adjustment circuit 72 adjusts the amplitude of the output signal W1 of the modulation circuit 70. With this configuration, the amplitude adjustment by the amplitude adjustment circuit 72 makes it possible to individually adjust the signal amount amplitude of the test signal M1 among the zero-point correction signal H1 and the test signal M1 in the combined signal G1.

[0104] (17-6) Variation 6 As shown in Figure 11, Modification 6 is configured similarly to Embodiment 1, except for a difference in the configuration of the signal waveform generation unit 352C. Modification 6 is configured to handle both cases where the difference signal is not zero and cases where the difference signal is zero. Embodiment 1 assumes the case where the difference signal is not zero.

[0105] The signal waveform generation unit 352C of the modified example 6 includes a pair of input terminals 79a, 79b, a pair of output terminals 80a, 80b, four switches SW1 to SW4, an AND circuit 75, a NOT circuit 76, and signal input terminals 77, 78.

[0106] A pair of input terminals 79a and 79b are connected to the phase adjustment unit 351. An inverted phase drive signal D2 from the phase adjustment unit 351 is input to one input terminal 79a. An inverted phase signal, which is the inverted phase of the inverted phase drive signal D2, is input to the other input terminal 79b.

[0107] A pair of output terminals 80a and 80b are connected to a pair of input terminals of the amplitude adjustment unit 353. The combined signal G1 generated by the signal waveform generation unit 352C is output from the pair of output terminals 80a and 80b. More specifically, the combined signal G1 is output from one output terminal 80a, and an inverted-phase signal, which is the combined signal G1 with its phase reversed, is output from the other output terminal 80b.

[0108] The signal input terminal 77 is connected to the zero-point output determination unit 36, and the zero-point signal invalidation signal F1 from the zero-point output determination unit 36 ​​is input to it. The zero-point signal invalidation signal F1 is a high-level signal if the zero-point signal (i.e., difference signal) is zero, and a low-level signal if the zero-point signal (i.e., difference signal) is not zero.

[0109] The signal input terminal 78 is connected to the test signal generation unit 34, and the test signal M1 from the test signal generation unit 34 is input to it.

[0110] Switch SW1 is located in the circuit E1 between input terminal 79a and output terminal 80a, and the circuit E1 is opened and closed by switching SW1 on and off. Switch SW2 is located in the circuit E2 between input terminal 79b and output terminal 80b, and the circuit E2 is opened and closed by switching SW2 on and off. Switches SW1 and SW2 are connected to the signal input terminal 78 and are controlled on and off by the test signal M1 from the signal input terminal 78. Switches SW1 and SW2 are turned on when the test signal M1 is a high-level signal and turned off when the test signal M1 is a low-level signal.

[0111] Switch SW3 is located in the circuit E3 between input terminal 79a and output terminal 80b, and the circuit E3 is opened and closed by switching SW3 on and off. Switch SW4 is located in the circuit E4 between input terminal 79a and output terminal 80b, and the circuit E4 is opened and closed by switching SW4 on and off. Switches SW3 and SW4 are connected to the output terminal 75c of the AND circuit 75 and are controlled on and off by the output signal of the AND circuit 75. Switches SW3 and SW4 are turned on when the output signal of the AND circuit 75 is a high-level signal, and turned off when the output signal of the AND circuit 75 is a low-level signal.

[0112] The AND gate 75 has input terminals 75a and 75b and output terminal 75c. Input terminal 75a is connected to the signal input terminal 77. Input terminal 75b is connected to the output terminal of the NOT gate 76. Output terminal 75c is connected to switches SW3 and SW4.

[0113] The NOT circuit 76 has an input terminal 76a and an output terminal 76b. The input terminal 76a is connected to the input terminal 75b of the AND circuit 75. The output terminal 76b is connected to the signal input terminal 78.

[0114] In this signal waveform generation unit 352C, if the difference signal (i.e., the zero-point signal) is not zero (first case), the zero-point signal invalidation signal F1 input to the signal input terminal 77 becomes a low-level signal. In the first case, if the test signal M1 input to the signal input terminal 78 is a high-level signal, switches SW1 and SW2 are turned on, and switches SW3 and SW4 are turned off. Therefore, a combined signal G1 is output from the output terminal 80a, which has the same phase (180 degrees) and amplitude as the inverse-phase drive signal D2 (see Figure 12). Also, in the first case, if the test signal M1 input to the signal input terminal 78 is a low-level signal, switches SW1 to SW4 are turned off. Therefore, a combined signal G1 with zero amplitude is output from the output terminal 80a (see Figure 12). Therefore, in the first case, as shown in Figure 12, the composite signal G1 has the same phase (180 degrees) and amplitude as the inverse-phase drive signal D2 during the high-level period of the test signal M1, and the amplitude is zero during the low-level period of the test signal M1. In other words, in the first case, the signal waveform generation unit 352C generates the same composite signal G1 as in Embodiment 1. The generated composite signal G1 is processed in the same way as in Embodiment 1.

[0115] On the other hand, if the difference signal (zero-point signal) is zero (second case), the zero-point signal invalidation signal F1 input to the signal input terminal 77 becomes a high-level signal. In the second case, if the test signal M1 input to the signal input terminal 78 is a high-level signal, switches SW1 and SW2 are turned on, and switches SW3 and SW4 are turned off. Therefore, a combined signal G1 is output from output terminal 80a with the same phase (180 degrees) and amplitude as the inverse-phase drive signal D2 (see Figure 13). Also, in the second case, if the test signal M1 input to the signal input terminal 78 is a low-level signal, switches SW1 and SW2 are turned off, and switches SW3 and SW4 are turned on. Therefore, a combined signal G1 is output from output terminal 80a with the opposite phase (0 degrees) and amplitude as the inverse-phase drive signal D2 (see Figure 13). Therefore, in the second case, as shown in Figure 13, the synthesized signal G1 is generated such that during the high-level period of the test signal M1, it has the same phase (180 degrees) and amplitude as the inverse-phase drive signal D2, and during the low-level period of the test signal M1, it has the opposite phase (0 degrees) and amplitude as the inverse-phase drive signal D2. In other words, the synthesized signal G1 is a signal that alternately repeats a phase interval of 0 degrees and a phase interval of 180 degrees. Thus, in the second case, the signal waveform generation unit 352C generates a synthesized signal G1 which is the same signal as the injected signal T1a after synthesis in Embodiment 1 (i.e., the signal obtained by superimposing the test signal M1 on the drive signal D1). The generated synthesized signal G1 is amplified by the amplitude adjustment unit 353, for example by an adjustment ratio of 1, converted from a voltage signal to a current signal by the voltage-current conversion unit 354, and injected into the circuit between the two detection electrodes 22 and the conversion circuit 41.

[0116] Based on the above, in the gyro sensor 1 according to Modification 6, when the difference signal is zero, the signal waveform generation unit 352C generates a signal as a composite signal G1 that alternately repeats a phase interval of 0 degrees and a phase interval of 180 degrees. With this configuration, when the difference signal is zero (i.e., zero-point correction is not required), an injection signal T1 (composite signal G1) can be generated that has the shape of the injection signal T1a after synthesis with the difference signal, without having to synthesize it with the difference signal.

[0117] (17-7) Modification 7 Modification 7 is configured similarly to Embodiment 1, except that the diagnostic circuit 61 and the diagnostic circuit 63 determine the threshold range based on the adjustment magnification.

[0118] The above adjustment ratio is the ratio by which the amplitude adjustment unit 353 adjusts (increases or decreases) the composite signal G1. The above threshold range is a threshold range used to determine whether the amplitude of the test signal M1 demodulated from the composite injection signal T1a falls within the threshold range.

[0119] If the adjustment ratio in the amplitude adjustment unit 353 is large, the amplitude of the test signal M1 demodulated from the combined injection signal T1a will be large. Therefore, it is necessary to change the threshold range in accordance with the increase in the amplitude of the test signal M1. That is, the diagnostic circuits 61 and 63 adjust the threshold range based on the adjustment ratio so that if the gyro sensor 1 is normal, the amplitude of the demodulated test signal M1 is included in the threshold range, and if the gyro sensor 1 is not normal, the amplitude of the demodulated test signal M1 is not included in the threshold range. Similarly, if the adjustment ratio in the amplitude adjustment unit 353 is small, the amplitude of the test signal M1 demodulated from the combined injection signal T1a will be small, so the diagnostic circuits 61 and 63 adjust the threshold range based on the adjustment ratio so that if the gyro sensor 1 is normal, the amplitude of the demodulated test signal M1 is included in the threshold range, and if the gyro sensor 1 is not normal, the amplitude of the demodulated test signal M1 is not included in the threshold range.

[0120] Based on the above, in the gyro sensor 1 according to Modification 7, the diagnostic circuit 61 determines the threshold range based on the adjustment magnification when the amplitude adjustment unit 353 adjusts the amplitude of the composite signal G1. The diagnostic circuit 61 performs fault diagnosis of the control unit U1 based on whether or not the amplitude of the test signal M1 included in the injection signal T1a falls within the threshold range. With this configuration, since the threshold range for fault diagnosis is determined based on the adjustment magnification in the amplitude adjustment unit 353, the threshold range for fault diagnosis can be appropriately determined based on the adjustment magnification.

[0121] Similarly, the diagnostic circuit 63 determines a threshold range based on the adjustment magnification used by the amplitude adjustment unit 353 when adjusting the amplitude of the composite signal G1. The diagnostic circuit 63 performs fault diagnosis of the control unit U1 based on whether or not the amplitude of the test signal M1 included in the injection signal T1a falls within the threshold range. With this configuration, since the threshold range for fault diagnosis is determined based on the adjustment magnification in the amplitude adjustment unit 353, the threshold range for fault diagnosis can be appropriately determined based on the adjustment magnification.

[0122] (Embodiment 2) The gyro sensor 1A according to Embodiment 2 will be described with reference to Figures 14 to 16.

[0123] The gyro sensor 1A according to Embodiment 2 is configured similarly to the gyro sensor 1 according to Embodiment 1, except that it further includes a quadrature loop circuit L2, a second demodulation circuit 51, a second connection circuit 52, and a diagnostic circuit 62 (second diagnostic circuit). In the following description, components identical to those in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted, while the description may focus on components that differ from Embodiment 1.

[0124] (1) Overall structure As shown in Figure 14, the gyro sensor 1A further comprises two quadrature correction electrodes 24, a second demodulation circuit 51, a second connection circuit 52, and a diagnostic circuit 62.

[0125] In Figure 14, the two quadrature correction electrodes 24 are shown adjacent to each other, but it is preferable that the two quadrature correction electrodes 24 are positioned on opposite sides of the oscillator 10 with respect to its center. In other words, it is preferable that the oscillator 10 is positioned between two corresponding quadrature correction electrodes 24.

[0126] In the gyro sensor 1A, among the detection signals S1 output from the detection electrode 22, signals with a predetermined phase (e.g., 90 degrees) that is different in phase from the drive signal D1 (0 degrees) are fed back to the oscillator 10 through the quadrature loop circuit L2. The quadrature loop circuit L2 includes the oscillator 10, a conversion circuit 41, a second demodulation circuit 51, a second connection circuit 52, and a quadrature feedback circuit 53.

[0127] Among the detection signals S1, signals with a predetermined phase different from the phase of the drive signal D1 are also called quadrature signals or unwanted signals. The phase difference between the drive signal D1 and the quadrature signal is, for example, 90 degrees. In the following explanation, the case where the phase difference between the drive signal D1 and the quadrature signal is 90 degrees will be used as an example. However, the phase difference is not limited to 90 degrees.

[0128] (2) Second demodulation circuit The second demodulation circuit 51 includes a phase shifter 511 and a mixer 512.

[0129] The phase shifter 511 shifts the phase of the drive signal D1 and outputs it to the mixer 512. More specifically, the phase shifter 511 shifts the phase of the drive signal D1 by 90 degrees and outputs it to the mixer 512.

[0130] The input terminal of mixer 512 is connected to the circuit between conversion circuit 41 and first demodulation circuit 42. Signal ST2 is input from conversion circuit 41 to mixer 512. Mixer 512 demodulates signal ST2 using the signal input from phase shifter 511. As a result, second demodulation circuit 51 generates demodulated signal ST4 by demodulating the signal component of signal ST2 output from conversion circuit 41 that has a different phase (90 degrees) from the drive signal D1.

[0131] (3) Second connection circuit The second connection circuit 52 includes an amplifier 521 and an AD converter 522.

[0132] The input terminal of amplifier 521 is connected to the output terminal of the second demodulation circuit 51. Amplifier 521 amplifies the demodulated signal ST4 output from the second demodulation circuit 51. The output terminal of amplifier 521 is connected to the analog input terminal of AD converter 522. AD converter 522 converts the demodulated signal ST4 output from amplifier 521 from an analog signal to a digital signal.

[0133] (4) Diagnostic circuit The diagnostic circuit 62 includes a bandpass filter 621 and a comparator 622.

[0134] The 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 signal component of the test signal M1 from the demodulated signal ST4.

[0135] The comparator 622 evaluates the amplitude of the signal components of the test signal M1 extracted by the bandpass filter 621. Specifically, the comparator 622 determines whether the amplitude falls within a threshold range. If the amplitude falls within the threshold range, the comparator 622 outputs a first signal; if the amplitude does not fall within the threshold range, the comparator 622 outputs a second signal. The first signal indicates that the circuit from the test signal generation unit 34 to the diagnostic circuit 62 is in a normal state. The second signal indicates that the circuit from the test signal generation unit 34 to the diagnostic circuit 62 is in an abnormal state. For example, if the gain of the circuit is abnormal, the comparator 622 outputs a second signal.

[0136] The circuit from the test signal generation unit 34 to the diagnostic circuit 62 includes the test signal generation unit 34, the signal generation unit 35, the conversion circuit 41, the second demodulation circuit 51, the second connection circuit 52, and the diagnostic circuit 62. In other words, the diagnostic circuit 62 uses the test signal M1 to determine whether or not there are any abnormalities in these circuits.

[0137] The comparator 622 outputs the determination result (first signal or second signal) to, for example, a memory device. The memory device stores the determination result. The memory device stores the determination result along with, for example, information about the time the determination was made.

[0138] (5) Quadrature Feedback Circuit The quadrature feedback circuit 53 includes a low-pass filter 531.

[0139] The demodulated signal ST4 output from the second connection circuit 52 is input to the quadrature feedback circuit 53. Based on the demodulated signal ST4, the quadrature feedback circuit 53 generates voltages to be applied to the two quadrature correction electrodes 24.

[0140] The input terminal of the low-pass filter 531 is connected to the output terminal of the second connection circuit 52. The 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, including the test signal component, from the demodulated signal ST4.

[0141] The quadrature feedback circuit 53 applies a voltage to the two quadrature correction electrodes 24, which suppresses the second-mode motion of the oscillator 10. Second-mode motion is the cause of the detection signal S1 containing a signal component (quadrature signal) that is in a different phase (e.g., 90 degrees) from the drive signal D1.

[0142] (6) Signal generation unit As shown in Figure 14, the signal generation unit 35 of Embodiment 2, like the signal generation unit 35 of Embodiment 1, includes a phase adjustment unit 351, a signal waveform generation unit 352D, an amplitude adjustment unit 353, two voltage-current conversion units 354, and two output terminals 355.

[0143] The signal generation unit 35 of Embodiment 2 is configured similarly to the signal generation unit 35 of Embodiment 1, except that the signal waveform generation unit 352D is different.

[0144] The signal waveform generation unit 352D generates a combined signal G1 by modulating the inverse phase drive signal D2 generated by the phase adjustment unit 351 using the test signal M1. As shown in Figure 15, the signal waveform generation unit 352D includes phase shifters 84 and 85 and a combining circuit 86.

[0145] The phase shifter 84 shifts the phase (180 degrees) of the inverse phase drive signal D2 from the phase adjustment unit 351 by +90 degrees to generate a phase adjustment signal D3 having the same amplitude and phase as the inverse phase drive signal D2, but with a different phase (270 degrees), and outputs it to the combining circuit 86.

[0146] The phase shifter 85 shifts the phase (180 degrees) of the inverse phase drive signal D2 from the phase adjustment unit 351 by -90 degrees to generate a phase adjustment signal D4 having the same amplitude and phase as the inverse phase drive signal D2, but with a different phase (90 degrees), and outputs it to the combining circuit 86.

[0147] The combining circuit 86 generates a combined signal G1 by combining the inverse phase drive signal D2 from the phase adjustment unit 351, the phase adjustment signal D3 from the phase shifter 84, and the phase adjustment signal D4 from the phase shifter 85, based on the test signal M1 from the test signal generation unit 34. More specifically, the combining circuit 86 combines the inverse phase drive signal D2 during the high-level period of the test signal M1, and during the low-level period of the test signal M1, it alternately combines the phase adjustment signals D3 and D4 each time the low-level period occurs. As a result, the combining circuit 86 generates a combined signal G1 in which 180-degree phase intervals are intermittently repeated, and 270-degree phase intervals and 90-degree phase intervals are alternately inserted between adjacent 180-degree phase intervals. In other words, the combining circuit 86 generates a combined signal G1 in which 90-degree phase intervals, 180-degree phase intervals, and 270-degree phase intervals are repeated.

[0148] The amplitude adjustment unit 353 generates an injection signal T1 (see Figure 16) from the synthesized signal G1 by adjusting the amplitude of the synthesized signal G1 generated by the synthesis circuit 86 to, for example, twice the original amplitude.

[0149] The voltage-to-current conversion unit 354 converts the amplitude-adjusted injection signal T1 output from the amplitude adjustment unit 353 from a voltage signal to a current signal and injects it into the circuit between the two detection electrodes 22 and the conversion circuit 41.

[0150] (7) Operation Description The operation of the gyro sensor 1A according to Embodiment 2 will be explained with reference to Figures 14 and 16. The following explanation describes the processing flow from when the injection signal T1 is injected into a predetermined circuit until it reaches the diagnostic circuits 61 to 63.

[0151] When the injected signal T1 is injected into the circuit between the two detection electrodes 22 and the conversion circuit 41, it is combined with the difference signal (i.e., the zero-point signal S0 (see Figure 16)) contained in the detection signal S1 output from the detection electrodes 22, and converted into the combined injected signal T1a (see Figure 16). This combination cancels out the difference signal, and the detection signal S1 containing the difference signal is converted into a detection signal S1a that does not contain the difference signal. Furthermore, during the high-level period of the test signal M1, the combined injected signal T1a becomes a signal U11 having the same phase (180 degrees) and amplitude (e.g., magnitude "1") as the inverse-phase drive signal D2, and during the low-level period of the test signal M1, it is a signal in which the first mixed signal U12 and the second mixed signal U13 are alternately combined each time the low-level period begins. The first mixed signal U12 is a signal in which a signal having the same phase (0 degrees) and amplitude (e.g., magnitude "1") as the drive signal D1 and a signal having the same phase (270 degrees) and amplitude (e.g., magnitude "2") as the phase and amplitude of the 270-degree phase interval of the injection signal T1 are mixed together. The second mixed signal U13 is a signal in which a signal having the same phase (0 degrees) and amplitude (e.g., magnitude "1") as the drive signal D1 and a signal having the same phase (90 degrees) and amplitude (e.g., magnitude "2") as the phase and amplitude of the 90-degree phase interval of the injection signal T1 are mixed together.

[0152] The injected signal T1a is input to the first demodulation circuit 42 via the conversion circuit 41. The injected signal T1a is also input to the second demodulation circuit 51 via the conversion circuit 41.

[0153] The first demodulation circuit 42 demodulates the signal component of the injected signal T1a that is in phase (0 degrees) with the drive signal D1 to demodulate the test signal M1. The demodulated test signal M1 is referred to as the demodulated test signal M1a. The waveform of the demodulated test signal M1a is as shown in the waveform of M1a in Figure 16. That is, in the signal U11 portion of the injected signal T1a, the amplitude (i.e., "1") of signal U11, which is in opposite phase (180 degrees) to the demodulation signal (drive signal D1), is negatively multiplied and demodulated as the demodulated test signal M1a. In addition, in the first mixed signal U12 portion of the injected signal T1a, the amplitude (i.e., magnitude "1") of a signal that is in phase (0 degrees) with the demodulation signal (drive signal D1) (a signal with a phase of 0 degrees and an amplitude of magnitude "1") is demodulated as the demodulated test signal M1a. Furthermore, in the second mixed signal U13 portion of the injection signal T1a, the amplitude (i.e., magnitude "1") of a signal that is in phase with the demodulation signal (drive signal D1) (i.e., a signal with a phase of 0 degrees and an amplitude of magnitude "1") is demodulated as the demodulation test signal M1a.

[0154] The demodulation test signal M1a is then input from the first demodulation circuit 42 through the first connection circuit 32 to the diagnostic circuit 61, where it is used to determine faults. Additionally, the demodulation test signal M1a is input from the first demodulation circuit 42 through the detection feedback circuit 43 to the diagnostic circuit 63, where it is used to determine faults.

[0155] Furthermore, the second demodulation circuit 51 demodulates the test signal M1 by demodulating the signal component of the injected signal T1a that is in a different phase (90 degrees phase) from the drive signal D1. The demodulated test signal M1 is referred to as the demodulated test signal M1b. The waveform of the demodulated test signal M1b is as shown in the waveform of M1b in Figure 16. That is, the signal U11 portion of the injected signal T1b does not contain a signal that is in phase with or out of phase with the demodulation signal (a signal with a 90-degree phase), so zero amplitude is demodulated as the demodulated test signal M1a. Also, in the first mixed signal U12 portion of the injected signal T1a, the amplitude (i.e., amplitude of magnitude "2") of the signal that is out of phase with the demodulation signal (a signal with a 90-degree phase) (i.e., a signal with a phase of 270 degrees and an amplitude of magnitude "2") is negatively multiplied and demodulated as the demodulated test signal M1b. Furthermore, in the second mixed signal U13 portion of the injected signal T1a, the amplitude (i.e., amplitude of magnitude "2") of a signal in phase with the demodulation signal (a signal with a 90-degree phase) (i.e., a signal with a 90-degree phase and an amplitude of magnitude "2") is demodulated as the demodulation test signal M1b.

[0156] The demodulation test signal M1b is then input from the second demodulation circuit 51 through the second connection circuit 52 to the diagnostic circuit 62, where it is used by the diagnostic circuit 62 to determine the fault.

[0157] (8) Effects As described above, the gyro sensor 1A according to Embodiment 2 includes a second demodulation circuit 51 and a diagnostic circuit 62 (second diagnostic circuit). The second demodulation circuit 51 has an input terminal. The input terminal is connected to the circuit between the conversion circuit 41 and the first demodulation circuit 42. The second demodulation circuit 51 generates a quadrature signal by demodulating the signal component of the detection signal S1 input to the input terminal that has a phase difference of 90 degrees from the drive signal D1. The diagnostic circuit 62 is connected downstream of the second demodulation circuit 51 and performs fault diagnosis of the control unit U1 based on the test signal M1 included in the quadrature signal, and generates a second fault diagnosis signal representing the fault diagnosis result. The signal waveform generation unit 352D generates a composite signal G1 having a phase interval of 90 degrees, a phase interval of 180 degrees, and a phase interval of 270 degrees by adjusting the phase of the zero-point correction signal H1 based on the test signal M1. With this configuration, fault diagnosis of the quadrature path can be performed with a simple configuration.

[0158] (9) Variant The following are examples of modifications of Embodiment 2. These modifications may be implemented by combining them as appropriate.

[0159] As shown in Figure 4, this modified example is configured similarly to Embodiment 2, except that the test signal generation unit 34 includes a duty cycle adjustment unit 341A.

[0160] The duty cycle adjustment unit 341A adjusts the duty cycle of the test signal M1 generated by the test signal generation unit 34 (i.e., the test signal M1 input to the signal generation unit 25).

[0161] In this modified example, as in Modification 1 of Embodiment 1, it is possible to adjust the amplitude of the test signal components (i.e., demodulated test signals M1a, M1b) included in the composite signal G1 by adjusting the duty cycle of the test signal M1.

[0162] Referring to Figure 17, calculate the amplitudes of the demodulated test signals M1a and M1b when the duty cycle of the test signal M1 is 0.75 in Embodiment 2. Note that the amplitude of the injection signal T1 in Embodiment 2 is "2", which corresponds to the case where the duty cycle of the test signal M1 is 0.5.

[0163] If the duty cycle of the test signal M1 is 0.75, the amplitude of the injection signal T1 will be "1.33" according to the relationship in Equation 1 below. Note that the zero-point signal S0 is the same signal as the drive signal D1, so if the amplitude of the drive signal D1 is "1", the amplitude of the zero-point signal S0 will be "1", and the amplitude of the injection signal T1 will be "1.33" according to Equation 1. [Injection signal amplitude] = [Zero-point signal amplitude] / Duty cycle ... Equation 1

[0164] The amplitude adjustment unit 353 generates an injection signal T1 having an amplitude of "1.33" by adjusting the composite signal G1 generated by the signal waveform generation unit 352D to 1.33 times its original value.

[0165] In this case, the waveforms of the injection signal T1, the combined injection signal T1a, and the demodulation test signals M1a and M1b are calculated in the same way as in Embodiment 2, and are shown in Figure 17. As can be seen from Figure 17, when the duty cycle is 0.75, the amplitudes of the demodulation test signals M1a and M1b change compared to the demodulation test signals M1a and M1b in Embodiment 2 (i.e., when the duty cycle is 0.5).

[0166] In this way, by adjusting the duty cycle of the test signal M1, it is possible to adjust the amplitude of the test signal M1 in the frequency domain (i.e., the demodulated test signals M1a and M1b) included in the composite signal G1.

[0167] Based on the above, in the modified gyro sensor 1A, the test signal generation unit 34 is equipped with a duty cycle adjustment unit 341A. The duty cycle adjustment unit 341A adjusts the duty cycle of the test signal M1. With this configuration, even in fault diagnosis of the quadrature path, the ratio of the signal amounts between the zero-point correction signal H1 included in the composite signal G1 and the test signal M1, i.e., the amplitude ratio, can be adjusted by adjusting the duty cycle of the test signal M1.

[0168] (summary) Based on the embodiments described above, the following aspects are disclosed.

[0169] A gyro sensor (1; 1A) according to the first embodiment comprises an oscillator (10), a plurality of electrodes (2), and a control unit (U1). The plurality of electrodes (2) include a drive electrode (21) and a detection electrode (22), and are arranged to face the oscillator (10), forming capacitance between them and the oscillator (10). The control unit (U1) is connected to the drive electrode (21) and the detection electrode (22). The control unit (U1) comprises a drive circuit (31), a conversion circuit (41), a first demodulation circuit (42), a detection processing circuit (33), a zero-point output determination unit (36), a test signal generation unit (34), a signal generation unit (35), and a first diagnostic circuit (61). The drive circuit (31) outputs a drive signal (D1) to the drive electrode (21) and induces drive vibration of the oscillator (10). The conversion circuit (41) converts the detection signal (S1) output from the detection electrode (22) from a current signal to a voltage signal. The first demodulation circuit (42) is connected downstream of the conversion circuit (41) and generates a demodulated detection signal by demodulating the signal component of the detection signal (S1) converted by the conversion circuit (41) that is in phase with the drive signal (D1). The detection processing circuit (33) is connected downstream of the first demodulation circuit (42) and generates an angular velocity signal representing the angular velocity of the oscillator (10) based on the above demodulated detection signal. The zero-point output determination unit (36) generates a difference signal that shows the difference between the angular velocity signal when no angular velocity is applied and the zero-point reference output value. The test signal generation unit (34) generates a test signal (M1). The signal generation unit (35) generates an injection signal (T1) to be injected into the circuit between the detection electrode (22) and the first demodulation circuit (42). The first diagnostic circuit (61) is connected downstream of the conversion circuit (41) and performs fault diagnosis of the control unit (U1) based on the injection signal (T1), and generates a fault diagnosis signal representing the fault diagnosis result. The signal generation unit (35) includes a phase adjustment unit (351), signal waveform generation units (352, 352A~352D), and a first amplitude adjustment unit (353). The phase adjustment unit (351) generates a zero-point correction signal (H1) from the drive signal (D1) to cancel out the difference signal contained in the detection signal (S1) by adjusting the phase of the drive signal (D1) to the opposite phase. The signal waveform generation units (352, 352A~352D) combine the test signal (M1) and the zero-point correction signal (H1) to generate a combined signal (G1).The first amplitude adjustment unit (353) generates an injection signal (T1) from the composite signal (G1) by adjusting the amplitude of the composite signal (G1).

[0170] With this configuration, the signal generation unit (35) can generate both the zero-point correction signal (H1) (i.e., the inverse phase drive signal (D2)) and the injection test signal (the test signal (M1) which is a combination of the inverse phase drive signal (D2)). This reduces the duplication of processing circuits with the same function (such as the phase adjustment unit (351) and the first amplitude adjustment unit (353)) between the signal generation circuits, compared to the case where the signal generation circuit for the zero-point correction signal and the signal generation circuit for the injection test signal are configured separately. As a result, the gyro sensor (1;1A) can be made smaller and more power-efficient.

[0171] In the gyro sensor (1;1A) according to the second embodiment, in the first embodiment, the signal waveform generation unit (352, 352A~352D) generates a composite signal (G1) by controlling the output of the zero-point correction signal (H1) generated by the phase adjustment unit (351) on and off based on the amplitude of the test signal (M1).

[0172] With this configuration, the signal waveform generation unit (352, 352A~352D) can be implemented with a simple configuration.

[0173] In the gyro sensor (1;1A) according to the third embodiment, in the first or second embodiment, the test signal generation unit (34) includes a duty cycle adjustment unit (341) for adjusting the duty cycle of the test signal (M1).

[0174] With this configuration, the ratio of the signal amounts (i.e., amplitude ratio) between the zero-point correction signal (H1) included in the composite signal (G1) and the test signal (M1) can be adjusted by adjusting the duty cycle of the test signal (M1).

[0175] In the gyro sensor (1;1A) according to the fourth embodiment, in any one of the first to third embodiments, the signal waveform generation unit (352, 352A to 352D) generates a composite signal (G1) by controlling the output of the zero-point correction signal (H1) on and off according to the high-level period (TH) and low-level period (TL) of the test signal (M1). The high-level period (TH) and low-level period (TL) of the test signal (M1) are integer multiples of the period of the drive signal (D1), respectively.

[0176] This configuration reduces the inclusion of a zero-point correction signal (H1) (i.e., an inverse-phase drive signal (D2)) that is cut off midway through one cycle in the combined signal (G1). As a result, zero-point correction by the zero-point correction signal (H1) (i.e., cancellation of the difference signal in the detection signal (S1)) can be performed with high accuracy.

[0177] In the fifth embodiment of the gyro sensor (1;1A), in any one of the first to fourth embodiments, the signal waveform generation unit (352A) includes a modulation circuit (70) and an adder (71). The modulation circuit (70) modulates the zero-point correction signal (H1) generated by the phase adjustment unit (351) based on a test signal (M1). The adder (71) adds the zero-point correction signal (H1) generated by the phase adjustment unit (351) and the output signal (W1) of the modulation circuit (70) to generate a composite signal (G1).

[0178] With this configuration, the signal waveform generation unit (352A) can be implemented with a simple configuration.

[0179] The gyro sensor (1;1A) according to the sixth embodiment further comprises a second amplitude adjustment unit (72) in the fifth embodiment, the second amplitude adjustment unit (72) being located between the modulation circuit (70) and the adder (71). The second amplitude adjustment unit (72) adjusts the amplitude of the output signal (W1) of the modulation circuit (70).

[0180] With this configuration, the amplitude adjustment by the second amplitude adjustment unit (72) allows for individual adjustment of the signal amount (amplitude) of the test signal (M1) among the zero-point correction signal (H1) and test signal (M1) in the composite signal (G1).

[0181] In the gyro sensor (1;1A) according to the seventh embodiment, if the difference signal is zero in any one of the first to sixth embodiments, the signal waveform generation unit (352, 352A to 352D) generates a combined signal (G1) which alternately repeats a phase interval of 0 degrees and a phase interval of 180 degrees.

[0182] With this configuration, if the difference signal is zero (i.e., zero-point correction is not required), the injected signal (T1) (composite signal (G1)) can be generated to have the form of the injected signal (T1a) after combining with the difference signal, without having to combine it with the difference signal.

[0183] In the gyro sensor (1;1A) according to the eighth embodiment, in any one of the first to seventh embodiments, the first diagnostic circuit (61) determines a threshold range based on the adjustment magnification when the first amplitude adjustment unit (353) adjusts the amplitude of the composite signal (G1). The first diagnostic circuit (61) diagnoses a fault in the control unit (U1) based on whether or not the amplitude of the test signal (M1) included in the injection signal (T1a) is within the threshold range.

[0184] With this configuration, the threshold range for fault diagnosis is determined based on the adjustment magnification in the first amplitude adjustment unit (353), so the threshold range for fault diagnosis can be appropriately determined based on the adjustment magnification.

[0185] The gyro sensor (1A) according to the ninth embodiment includes, in any one of the first to eighth embodiments, a second demodulation circuit (51) and a second diagnostic circuit (62). The second demodulation circuit (51) has an input terminal. The input terminal is connected to the circuit between the conversion circuit (41) and the first demodulation circuit (42). The second demodulation circuit (51) generates a quadrature signal by demodulating the signal component of the detection signal (S1) input to the input terminal that is 90 degrees out of phase with the drive signal (D1). The second diagnostic circuit (62) is connected downstream of the second demodulation circuit (51) and performs fault diagnosis of the control unit (U1) based on the test signal (M1) included in the quadrature signal, and generates a second fault diagnosis signal representing the fault diagnosis result. The signal waveform generation unit (352D) generates a composite signal (G1) having phase intervals of 90 degrees, 180 degrees, and 270 degrees by adjusting the phase of the zero-point correction signal (H1) based on the test signal (M1).

[0186] This configuration allows for fault diagnosis of the quadrature path with a simple setup.

[0187] In the gyro sensor (1A) according to the tenth embodiment, the test signal generation unit (34) includes a duty cycle adjustment unit (341A) as in the ninth embodiment. The duty cycle adjustment unit (341A) adjusts the duty cycle of the test signal (M1).

[0188] With this configuration, even in fault diagnosis of the quadrature path, the ratio of the signal amounts (i.e., amplitude ratio) between the zero-point correction signal (H1) included in the composite signal (G1) and the test signal (M1) can be adjusted by adjusting the duty cycle of the test signal (M1).

[0189] In the 11th embodiment of the gyro sensor (1;1A), in any one of the first to tenth embodiments, the injection signal (T1) is combined with the difference signal included in the detection signal (S1) output from the detection electrode (22) to convert it into a signal (T1a) in which the test signal (M1) is superimposed on the drive signal (D1).

[0190] This configuration allows the injected signal (T1) to cancel out the difference signal within the detection signal (S1). Furthermore, the combined injected signal (T1a) can enable the test signal (M1) to reach the diagnostic circuit. [Explanation of symbols]

[0191] 1.1A Gyro Sensor 10 oscillators 2 Multiple electrodes 21 Driving electrode 22 Detection electrodes 31 Drive Circuit 33 Detection Processing Circuit 34 Test signal generation unit 35 Signal Generation Unit 36 Zero-point output determination unit 41 Conversion Circuit 42 First demodulation circuit 51 Second demodulation circuit 61 Diagnostic Circuit (First Diagnostic Circuit) 62 Diagnostic Circuit (Second Diagnostic Circuit) 70 Modulation Circuit 71 Adder 341, 341A Duty Cycle Adjustment Section 351 Phase adjustment section 352,352A~352D Signal waveform generation section 353 1st amplitude adjustment section D1 drive signal G1 composite signal H1 Zero-point correction signal M1 Test Signal S1 detection signal T1,T1a injection signal U1 Control Unit W1 output signal

Claims

1. The oscillator and, A plurality of electrodes, including a drive electrode and a detection electrode, are arranged to face the vibrator and form a capacitance between them and the vibrator. The system comprises the drive electrode and a control unit connected to the detection electrode, The control unit, A drive circuit that outputs a drive signal to the drive electrode and induces drive vibration of the vibrator, A conversion circuit that converts the detection signal output from the detection electrode from a current signal to a voltage signal, A first demodulation circuit is connected downstream of the aforementioned conversion circuit and generates a demodulated detection signal by demodulating the signal component of the detection signal converted by the conversion circuit that is in phase with the drive signal, A detection processing circuit connected downstream of the first demodulation circuit generates an angular velocity signal representing the angular velocity of the oscillator based on the demodulation detection signal, A zero-point output determination unit generates a difference signal that indicates the difference between the angular velocity signal and the zero-point reference output value when the angular velocity is not applied, A test signal generation unit that generates a test signal, A signal generation unit that generates an injection signal to be injected into the circuit between the detection electrode and the first demodulation circuit, The system includes a first diagnostic circuit connected downstream of the conversion circuit, which performs fault diagnosis of the control unit based on the injection signal and generates a fault diagnosis signal representing the fault diagnosis result, The signal generation unit, A phase adjustment unit generates a zero-point correction signal from the drive signal to cancel out the difference signal included in the detection signal by adjusting the phase of the drive signal to the opposite phase, A signal waveform generation unit that generates a combined signal by combining the test signal and the zero-point correction signal, The system includes a first amplitude adjustment unit that generates the injection signal from the composite signal by adjusting the amplitude of the composite signal. Gyroscope sensor.

2. The signal waveform generation unit generates the composite signal by controlling the output of the zero-point correction signal generated by the phase adjustment unit on and off based on the amplitude of the test signal. The gyro sensor according to claim 1.

3. The test signal generation unit includes a duty cycle adjustment unit for adjusting the duty cycle of the test signal. The gyro sensor according to claim 1 or 2.

4. The signal waveform generation unit generates the composite signal by controlling the output of the zero-point correction signal on and off according to the high-level and low-level periods of the test signal. The high-level period and the low-level period of the test signal are, respectively, integer multiples of the period of the drive signal. The gyro sensor according to claim 1 or 2.

5. The signal waveform generation unit, A modulation circuit that modulates the zero-point correction signal generated by the phase adjustment unit based on the test signal, The system includes an adder that generates the combined signal by adding the zero-point correction signal generated by the phase adjustment unit and the output signal of the modulation circuit. The gyro sensor according to claim 1 or 2.

6. The system further comprises a second amplitude adjustment unit provided between the modulation circuit and the adder, The second amplitude adjustment unit adjusts the amplitude of the output signal of the modulation circuit. The gyro sensor according to claim 5.

7. If the difference signal is zero, the signal waveform generation unit generates a signal as the composite signal that alternately repeats a phase interval of 0 degrees and a phase interval of 180 degrees. The gyro sensor according to claim 1 or 2.

8. The first diagnostic circuit determines a threshold range based on the adjustment magnification used by the first amplitude adjustment unit when adjusting the amplitude of the composite signal, and performs the fault diagnosis of the control unit based on whether or not the amplitude of the test signal included in the injection signal falls within the threshold range. The gyro sensor according to claim 1 or 2.

9. A second demodulation circuit has an input terminal connected to the circuit between the conversion circuit and the first demodulation circuit, and generates a quadrature signal by demodulating the signal component of the detection signal input to the input terminal that is 90 degrees out of phase with the drive signal, The system includes a second diagnostic circuit connected downstream of the second demodulation circuit, which performs fault diagnosis of the control unit based on the test signal included in the quadrature signal and generates a second fault diagnosis signal representing the fault diagnosis result, The signal waveform generation unit generates the composite signal having a phase interval of 90 degrees, a phase interval of 180 degrees, and a phase interval of 270 degrees by adjusting the phase of the zero-point correction signal based on the test signal. The gyro sensor according to claim 1 or 2.

10. The test signal generation unit includes a duty cycle adjustment unit for adjusting the duty cycle of the test signal. The gyro sensor according to claim 9.

11. The injection signal is combined with the difference signal included in the detection signal output from the detection electrode to convert it into a signal in which the test signal is superimposed on the drive signal. The gyro sensor according to claim 1 or 2.

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