Physical quantity detection circuit, physical quantity sensor, electronic device, and moving body

Abstract

A physical quantity detection circuit, a physical quantity sensor, an electronic device, and a moving body. The physical quantity detection circuit includes: a drive circuit that excites a physical quantity detection element to vibrate; a differential amplifier circuit that differentially amplifies a signal pair based on a first signal and a second signal output from the physical quantity detection element; a first synchronous detector circuit that synchronously detects a signal based on the output signal of the differential amplifier circuit; a physical quantity detection signal generation circuit that generates a physical quantity detection signal based on the output signal of the first synchronous detector circuit; an adder circuit that adds the signal pair; a second synchronous detector circuit that synchronously detects a signal based on the output signal of the adder circuit; and a vibration leakage signal generation circuit that generates a vibration leakage signal based on the output signal of the second synchronous detector circuit.

Description

[0001] This application is a divisional application of the invention patent application filed on April 21, 2020, with application number 202010316045.5 and entitled "Physical quantity detection circuit, physical quantity sensor and fault diagnosis method thereof". Technical Field

[0002] This invention relates to physical quantity detection circuits, physical quantity sensors, electronic devices, and moving bodies. Background Technology

[0003] Currently, gyroscopes (detecting angular velocity) and accelerometers (detecting acceleration), capable of detecting various physical quantities, are widely used in various systems and electronic devices. In recent years, to achieve high reliability in systems using physical quantity sensors, methods for diagnosing faults within these sensors have been proposed.

[0004] For example, Patent Document 1 describes a physical quantity detection device with a physical quantity detection circuit. In an abnormality diagnosis mode, this circuit detects leakage vibrations generated at the two detection vibrating arms due to the bending vibrations of the two driving vibrating arms of the physical quantity detection element, and outputs a signal corresponding to the magnitude of the leakage vibrations. Specifically, in the physical quantity detection device described in Patent Document 1, the physical quantity detection circuit, in physical quantity detection mode, uses a synchronous detection circuit to synchronously detect the signal differentially amplified from the two detection electrodes of the physical quantity detection element by a differential amplifier circuit, generating a signal corresponding to the physical quantity component. In an abnormality diagnosis mode, the physical quantity detection circuit uses both the differential amplifier circuit and the synchronous detection circuit, outputting a signal corresponding to the vibration leakage component by changing the phase of the detection signal input to the synchronous detection circuit. In the event of a fault such as damage to the physical quantity detection element, the magnitude of the leakage vibration changes, thus changing the magnitude of the signal output from the physical quantity detection circuit in abnormality diagnosis mode. Therefore, fault diagnosis can be performed based on the signal output from the physical quantity detection circuit.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-107416

[0006] However, in the physical quantity detection device described in Patent Document 1, the physical quantity detection element is adjusted so that the vibration leakage components contained in the signals output from the two detection electrodes are out of phase. The output signal of the differential amplifier circuit contains both physical quantity components and a relatively large vibration leakage component. Therefore, in physical quantity detection mode, when the phase of the detection signal deviates from the design value due to manufacturing deviations, a relatively large vibration leakage component is contained in the output signal of the synchronous detection circuit. Thus, in physical quantity detection mode, there is a concern that the noise component in the signal output from the physical quantity detection circuit increases, and the zero point of the physical quantity detection signal when no physical quantity is applied deviates from the design value by an uncertain amount. Summary of the Invention

[0007] One embodiment of the physical quantity detection circuit of the present invention is a physical quantity detection circuit comprising: a driving circuit that excites a physical quantity detection element for detecting the physical quantity to vibrate; a differential amplifier circuit that differentially amplifies a signal pair based on a first signal and a second signal output from the physical quantity detection element; a first synchronous detector circuit that synchronously detects a signal based on the output signal of the differential amplifier circuit; a physical quantity detection signal generation circuit that generates a physical quantity detection signal based on the output signal of the first synchronous detector circuit; an adder circuit that adds the signal pair; a second synchronous detector circuit that synchronously detects a signal based on the output signal of the adder circuit; and a vibration leakage signal generation circuit that generates a vibration leakage signal based on the output signal of the second synchronous detector circuit.

[0008] Alternatively, the physical quantity detection circuit may include a fault diagnosis circuit that performs fault diagnosis based on the vibration leakage signal.

[0009] One embodiment of the physical quantity detection circuit may include: a first charge amplifier circuit that receives the first signal; and a second charge amplifier circuit that receives the second signal, wherein the signal pair is a signal pair consisting of the output signal of the first charge amplifier circuit and the output signal of the second charge amplifier circuit.

[0010] Alternatively, the physical quantity detection circuit may include a smoothing circuit that smooths the output signal of the second synchronous detection circuit to output a DC voltage signal.

[0011] Alternatively, the physical quantity detection circuit may include a vibration leakage signal generation circuit that incorporates a variable amplifier circuit, which amplifies or attenuates the DC voltage signal before outputting it.

[0012] Alternatively, the physical quantity detection circuit may include a vibration leakage signal generation circuit that incorporates a filtering circuit, which outputs the vibration leakage signal by limiting the output signal of the variable amplifier circuit to a desired frequency band.

[0013] Alternatively, the physical quantity detection circuit may be configured such that the first signal includes a first vibration leakage component, and the second signal includes a second vibration leakage component.

[0014] In another configuration of the physical quantity detection circuit, the first vibration leakage component and the second vibration leakage component are in phase with each other.

[0015] In another embodiment of the physical quantity detection circuit, the vibration leakage signal is an analog signal, and the vibration leakage signal generation circuit includes an analog-to-digital conversion circuit, which converts the vibration leakage signal into a digital signal and then outputs it.

[0016] One embodiment of the physical quantity sensor of the present invention includes: one embodiment of the physical quantity detection circuit; and a physical quantity detection element.

[0017] One aspect of the electronic device of the present invention includes: a physical quantity sensor; a storage unit; and a processing circuit that processes data based on the output signal of the physical quantity sensor and the data stored in the storage unit.

[0018] One aspect of the mobile body of the present invention includes: a physical quantity sensor; a processing circuit that controls the attitude based on the output signal of the physical quantity sensor; and a navigation device that determines the position based on the output signal of the physical quantity sensor. Attached Figure Description

[0019] Figure 1 This is a functional block diagram of the physical quantity sensor in this embodiment.

[0020] Figure 2 This is a top view of the vibrating plate of the gyroscope sensor element.

[0021] Figure 3 This diagram is used to illustrate the operation of a gyroscope sensor element.

[0022] Figure 4 This diagram is used to illustrate the operation of a gyroscope sensor element.

[0023] Figure 5 This is a diagram showing an example of the structure of a drive circuit.

[0024] Figure 6 This is a diagram showing an example of the structure of a detection circuit.

[0025] Figure 7 This is a diagram illustrating an example of the waveforms of various signals containing the physical quantity components of the output signal of a physical quantity detection element.

[0026] Figure 8 This is a diagram illustrating an example of the waveforms of various signals containing the vibration leakage component in the output signal of a physical quantity detection element.

[0027] Figure 9 This is a flowchart illustrating an example of the steps of the fault diagnosis method of this embodiment.

[0028] Figure 10 This is a functional block diagram illustrating an example of the structure of the electronic device according to this embodiment.

[0029] Figure 11 This is a schematic perspective view of a digital camera as an example of an electronic device.

[0030] Figure 12 This is a diagram illustrating an example of the movable body of this embodiment.

[0031] Label Explanation

[0032] 1: Physical quantity sensor; 5: MCU; 10: Reference voltage circuit; 20: Drive circuit; 21: Current-to-voltage conversion circuit; 22: AC amplifier circuit; 23: Amplitude adjustment circuit; 24: Phase shifting circuit; 30: Detection circuit; 31A: Charge amplifier circuit; 31B: Charge amplifier circuit; 32: Differential amplifier circuit; 33: Adder circuit; 34A: AC amplifier circuit; 34B: AC amplifier circuit; 35A: Synchronous detector circuit; 35B: Synchronous detector circuit; 3 6A: Smoothing circuit; 36B: Smoothing circuit; 37A: Variable amplifier circuit; 37B: Variable amplifier circuit; 38A: Filter circuit; 38B: Filter circuit; 41: Analog / digital conversion circuit; 42: Analog / digital conversion circuit; 51: Digital signal processing circuit; 52: Digital signal processing circuit; 60: Fault diagnosis circuit; 70: Interface circuit; 80: Storage unit; 90: Oscillator circuit; 100: Physical quantity detection element; 101a, 101b: Drive vibrating arm; 1 02: Vibration arm for detection; 103: Weighting part; 104a, 104b: Drive base; 105a, 105b: Connecting arm; 106: Weighting part; 107: Detection base; 112, 113: Drive electrode; 114, 115: Detection electrode; 116: Common electrode; 200: Physical quantity detection circuit; 300: Electronic device; 310: Physical quantity sensor; 320: Processing circuit; 330: Operation part; 340: ROM; 350: RAM; 360: Communication unit; 370: Display unit; 400: Moving body; 410: Physical quantity sensor; 440, 450, 460: Processing circuit; 470: Battery; 480: Navigation device; 1300: Digital camera; 1302: Housing; 1304: Light receiving unit; 1306: Shutter button; 1308: Memory; 1310: Display unit; 1312: Video signal output terminal; 1314: Input / output terminal; 1430: Television monitor; 1440: Personal computer. Detailed Implementation

[0033] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, the embodiments described below are not intended to unduly limit the scope of the invention as defined in the claims. Additionally, not all structures described below are essential technical features of the present invention.

[0034] The following explanation will be based on an angular velocity sensor, a physical quantity sensor that detects angular velocity as a physical quantity.

[0035] 1. Physical quantity sensor

[0036] 1-1. Structure of a physical quantity sensor

[0037] Figure 1This is a functional block diagram of the physical quantity sensor of this embodiment. The physical quantity sensor 1 of this embodiment includes a physical quantity detection element 100 and a physical quantity detection circuit 200 for detecting physical quantities.

[0038] The physical quantity sensing element 100 has a vibrating plate configured with a drive electrode and a detection electrode. Generally, in order to minimize the impedance of the vibrating plate and improve the oscillation efficiency, the vibrating plate is sealed in a hermetically sealed package. In this embodiment, the physical quantity sensing element 100 has a so-called double-T type vibrating plate, which has two T-shaped drive vibrating arms.

[0039] Figure 2 This is a top view of the vibrating plate of the physical quantity detection element 100 according to this embodiment. The physical quantity detection element 100, for example, has a double-T-shaped vibrating plate formed from a Z-cut quartz substrate. The resonant frequency of a quartz vibrating plate varies very little with temperature changes, thus offering the advantage of improved angular velocity detection accuracy. Furthermore, Figure 2 The X, Y, and Z axes in the diagram represent the axes of the quartz crystal.

[0040] like Figure 2 As shown, in the vibrating plate of the physical quantity detection element 100, driving vibration arms 101a and 101b extend from two driving bases 104a and 104b respectively in the +Y-axis direction and the -Y-axis direction. Driving electrodes 112 and 113 are formed on the side and top surfaces of the driving vibration arm 101a, respectively, and driving electrodes 113 and 112 are formed on the side and top surfaces of the driving vibration arm 101b, respectively. The driving electrodes 112 and 113 are respectively connected via... Figure 1 The physical quantity detection circuit 200 shown is connected to the drive circuit 20 via its DS and DG terminals.

[0041] The driving bases 104a and 104b are connected to the rectangular detection base 107 via connecting arms 105a and 105b extending in the -X-axis direction and the +X-axis direction, respectively.

[0042] The detection vibrating arm 102 extends from the detection base 107 in the +Y axis direction and the -Y axis direction. Detection electrodes 114 and 115 are formed on the upper surface of the detection vibrating arm 102, and a common electrode 116 is formed on the side surface of the detection vibrating arm 102. The detection electrodes 114 and 115 are respectively connected via... Figure 1 The S1 and S2 terminals of the physical quantity detection circuit 200 shown are connected to the detection circuit 30. Additionally, the common electrode 116 is grounded.

[0043] When an AC voltage is applied as a driving signal between the driving electrodes 112 and 113 of the driving vibrating arms 101a and 101b, such as Figure 3As shown, due to the inverse piezoelectric effect, the front ends of the two driving vibration arms 101a and 101b undergo repeated bending vibrations, approaching and separating from each other, as indicated by arrow B. Hereinafter, the bending vibrations of the driving vibration arms 101a and 101b are sometimes referred to as "excitation vibrations".

[0044] In this state, when an angular velocity with the Z-axis as the rotation axis is applied to the vibrating plate of the physical quantity detection element 100, the driving vibrating arms 101a and 101b obtain a Coriolis force in a direction perpendicular to both the bending vibration direction indicated by arrow B and the Z-axis. The result is as follows: Figure 4 As shown, connecting arms 105a and 105b vibrate as indicated by arrow C. Furthermore, the detection vibrating arm 102, in conjunction with the vibrations of connecting arms 105a and 105b, undergoes bending vibration as indicated by arrow D. The bending vibration of the detection vibrating arm 102, accompanied by the Coriolis force, and the bending vibration of the driving vibrating arms 101a and 101b are 90° out of phase.

[0045] Furthermore, if the magnitude of the vibration energy or the amplitude of the vibration when the driving vibration arms 101a and 101b undergo bending vibration is equal in both driving vibration arms 101a and 101b, a balance of vibration energy is achieved in the driving vibration arms 101a and 101b. In the absence of an angular velocity applied to the physical quantity detection element 100, the detection vibration arm 102 does not undergo bending vibration. However, when the balance of vibration energy between the two driving vibration arms 101a and 101b is disrupted, the detection vibration arm 102 will produce bending vibration even without an angular velocity applied to the physical quantity detection element 100. This bending vibration is called leakage vibration, and it is the bending vibration indicated by arrow D, similar to the vibration based on the Coriolis force, but with a 90° phase shift from the Coriolis force-based vibration.

[0046] Furthermore, alternating current charges based on these bending vibrations are generated on the detection electrodes 114 and 115 of the detection vibrating arm 102 via the piezoelectric effect. Here, the alternating current charges generated based on the Coriolis force vary depending on the magnitude of the Coriolis force, i.e., the magnitude of the angular velocity applied to the physical quantity detection element 100. On the other hand, the alternating current charges generated based on leakage vibrations are constant and independent of the magnitude of the angular velocity applied to the physical quantity detection element 100.

[0047] Furthermore, a rectangular weighting portion 103, wider than the driving vibration arms 101a and 101b, is formed at the front end of each driving vibration arm 101a and 101b. By forming the weighting portion 103 at the front end of the driving vibration arms 101a and 101b, the Coriolis force can be increased, and the desired resonant frequency can be obtained with a relatively short vibration arm. Similarly, a weighting portion 106, wider than the detection vibration arm 102, is formed at the front end of the detection vibration arm 102. By forming the weighting portion 106 at the front end of the detection vibration arm 102, the alternating current charge generated at the detection electrodes 114 and 115 can be increased.

[0048] As described above, the physical quantity detection element 100 outputs alternating current (AC) charge based on the detected physical quantity and alternating current (AC) charge based on leakage vibration from the excitation vibration via detection electrodes 114 and 115. Hereinafter, the AC charge based on the physical quantity will sometimes be referred to as the "physical quantity component," and the AC charge based on the leakage vibration will sometimes be referred to as the "vibration leakage component." Furthermore, in this embodiment, the physical quantity detected by the physical quantity detection element 100 is the angular velocity corresponding to the Coriolis force.

[0049] return Figure 1 As described above, the physical quantity detection circuit 200 includes a reference voltage circuit 10, a drive circuit 20, a detection circuit 30, an analog-to-digital conversion circuit 41, an analog-to-digital conversion circuit 42, a digital signal processing circuit 51, a digital signal processing circuit 52, a fault diagnosis circuit 60, an interface circuit 70, a storage unit 80, and an oscillation circuit 90. The physical quantity detection circuit 200 can be implemented, for example, using a single-chip integrated circuit (IC). Alternatively, the physical quantity detection circuit 200 can also be a structure that omits or modifies some of these elements or adds other elements.

[0050] The reference voltage circuit 10 generates a constant voltage and a constant current, such as a reference voltage simulating ground voltage, based on the power supply voltage and ground voltage supplied from the VDD terminal and VSS terminal of the physical quantity detection circuit 200, respectively, and supplies them to the drive circuit 20 and the detection circuit 30.

[0051] The drive circuit 20 generates a drive signal to excite the physical quantity detection element 100 to vibrate, and supplies it to the drive electrode 112 of the physical quantity detection element 100 via the DS terminal. Additionally, the oscillating current generated at the drive electrode 113 by the excitation vibration of the physical quantity detection element 100 is input to the drive circuit 20 via the DG terminal. The drive circuit 20 performs feedback control on the amplitude level of the drive signal to keep the amplitude of the oscillating current constant. Furthermore, the drive circuit 20 generates a detector signal SDET with the same phase as the drive signal and a detector signal QDET with a phase difference of 90° from the drive signal, and outputs them to the detection circuit 30.

[0052] The alternating current (AC) charges generated by the two detection electrodes 114 and 115 of the physical quantity detection element 100 are input to the detection circuit 30 via terminals S1 and S2 of the physical quantity detection circuit 200, respectively. The detection circuit 30 uses the detector signal SDET to detect the physical quantity components contained in these AC charges, generates an analog signal corresponding to the voltage level and magnitude of the physical quantity components, namely the physical quantity detection signal SAO, and outputs it. Additionally, the detection circuit 30 detects the vibration leakage component contained in the AC charges input via terminals S1 and S2, generates an analog signal corresponding to the voltage level and magnitude of the vibration leakage component, namely the vibration leakage signal QAO, and outputs it.

[0053] The storage unit 80 has a non-volatile memory (not shown) that stores various trimming data, such as adjustment data or correction data, for the drive circuit 20 and the detection circuit 30. The non-volatile memory can be configured as, for example, a MONOS (Metal Oxide Nitride Oxide Silicon) type memory or an EEPROM (Electrically Erasable Programmable Read-Only Memory). Alternatively, the storage unit 80 can be configured to have a register (not shown) in which, when the physical quantity detection circuit 200 is powered on (i.e., when the voltage at the VDD terminal rises from 0V to a desired voltage), the various trimming data stored in the non-volatile memory is transferred and stored in the register, and the various trimming data stored in the register is supplied to the drive circuit 20 and the detection circuit 30.

[0054] The analog-to-digital conversion circuit 41 operates according to the clock signal ADCLK, converting the physical quantity detection signal SAO, which is an analog signal, into the physical quantity detection signal SDO, which is a digital signal, and then outputting it.

[0055] The analog-to-digital converter 42 operates according to the clock signal ADCLK, converting the vibration leakage signal QAO, which is an analog signal, into a vibration leakage signal QDO, which is a digital signal, and then outputting it.

[0056] The digital signal processing circuit 51 operates according to the master clock signal MCLK, performs prescribed calculations on the physical quantity detection signal SDO output from the analog-to-digital conversion circuit 41, and outputs the physical quantity detection signal SDOX obtained through the calculations.

[0057] The digital signal processing circuit 52 operates according to the master clock signal MCLK, performs prescribed calculations on the vibration leakage signal QDO output from the analog-to-digital conversion circuit 42, and outputs the vibration leakage signal QDOX obtained through the calculations.

[0058] The fault diagnosis circuit 60 operates based on the master clock signal MCLK and performs fault diagnosis on the physical quantity sensor 1 based on the vibration leakage signal QDOX. Then, the fault diagnosis circuit 60 outputs a fault diagnosis result signal QF indicating whether the physical quantity sensor 1 is faulty. If the physical quantity sensor 1 is normal, the magnitude of the vibration leakage signal QDOX is within a specified range. Conversely, for example, if a portion of the physical quantity sensing element 100 is damaged, a portion of the wiring electrically connected to the sensing electrode 114 of the physical quantity sensing element 100 is cut or short-circuited, or a portion of the wiring electrically connected to the sensing electrode 115 of the physical quantity sensing element 100 is cut or short-circuited, the magnitude of the vibration leakage signal QDOX deviates from the specified range. Therefore, the fault diagnosis circuit 60 can diagnose a fault in the physical quantity sensor 1 if the magnitude of the vibration leakage signal QDOX is not within the first range. For example, the first range can be set to a design value that includes the vibration leakage signal QDOX, and includes a range that can vary from that design value over time. Furthermore, the first range can be either fixed or variable. For example, the first range can be variably set according to the value stored in the register of the storage unit 80 that can be rewritten from outside the physical quantity detection circuit 200.

[0059] The interface circuit 70, upon request from the external device, the MCU (Micro Control Unit), of the physical quantity detection circuit 200, processes the output of the physical quantity detection signal SDOX and the fault diagnosis result signal QF from the digital signal processing circuit 51 to the MCU 5. Additionally, the interface circuit 70 can also, upon request from the MCU 5, process the output of the vibration leakage signal QDOX from the digital signal processing circuit 52 to the MCU 5. Furthermore, the interface circuit 70, upon request from the MCU 5, processes the reading of data stored in the non-volatile memory or register of the storage unit 80 and outputs it to the MCU 5, and processes the writing of data input from the MCU 5 to the non-volatile memory or register of the storage unit 80. For example, the MCU 5 can also process the writing of a value used to set the aforementioned first range to a specified register.

[0060] Interface circuit 70 is, for example, an interface circuit for an SPI (Serial Peripheral Interface) bus. The select signal, clock signal, and data signal sent from MCU 5 are input to interface circuit 70 via the SS terminal, SCLK terminal, and SI terminal of physical quantity detection circuit 200, respectively. Interface circuit 70 outputs the data signal to MCU 5 via the SO terminal of physical quantity detection circuit 200. Alternatively, interface circuit 70 can also be connected to various buses other than SPI, such as I... 2 C (Inter-Integrated Circuit) bus and other corresponding interface circuits.

[0061] Oscillator circuit 90 generates a master clock signal MCLK and supplies it to digital signal processing circuits 51 and 52, as well as fault diagnosis circuit 60. Additionally, oscillator circuit 90 divides the master clock signal MCLK to generate a clock signal ADCLK, and supplies ADCLK to analog-to-digital conversion circuits 41 and 42. Oscillator circuit 90 can also generate the master clock signal MCLK, for example, using a ring oscillator or a CR oscillator circuit.

[0062] In the physical quantity sensor 1 configured in this way, the physical quantity detection element 100 outputs a first signal and a second signal. The first signal is an alternating charge generated by the detection electrode 114, and the second signal is an alternating charge generated by the detection electrode 115. The physical quantity detection circuit 200 generates a physical quantity detection signal SDOX corresponding to the physical quantity detected by the physical quantity detection element 100 based on the first signal and the second signal output from the physical quantity detection element 100.

[0063] 1-2. Structure of the driving circuit

[0064] Figure 5 This is a diagram showing an example of the structure of the drive circuit 20. (As shown...) Figure 5 As shown, the driving circuit 20 includes a current-to-voltage conversion circuit 21, an AC amplifier circuit 22, an amplitude adjustment circuit 23, and a phase shifting circuit 24.

[0065] The oscillating current generated by the excitation vibration of the physical quantity detection element 100 on the drive electrode 113 is input to the current-to-voltage conversion circuit 21 via the DG terminal, and is converted into an AC voltage signal by the current-to-voltage conversion circuit 21. The AC voltage signal output from the current-to-voltage conversion circuit 21 is input to the AC amplifier circuit 22 and the amplitude adjustment circuit 23.

[0066] AC amplifier circuit 22 amplifies the input AC voltage signal and clamps it with a specified voltage value to output a square wave drive signal. Amplitude adjustment circuit 23 controls AC amplifier circuit 22 according to the level of AC voltage signal output by current-voltage conversion circuit 21 to change the amplitude of drive signal, so that the amplitude of oscillation current remains constant.

[0067] The drive signal output from the AC amplifier circuit 22 is supplied to the drive electrode 112 of the physical quantity detection element 100 via the DS terminal. The physical quantity detection element 100 can continue to vibrate by being supplied with the drive signal. In addition, by keeping the oscillation current constant, the drive vibration arms 101a and 101b of the physical quantity detection element 100 can obtain a constant vibration velocity. Therefore, since the vibration velocity, which is the basis for the generation of the Coriolis force, is constant, the sensitivity can be made more stable.

[0068] Additionally, the AC amplifier circuit 22 outputs a square wave detector signal SDET that is in phase with the drive signal, and the phase shifter circuit 24 outputs a detector signal QDET that leads the phase of the detector signal SDET by 90°. Then, the detector signals SDET and QDET are supplied to the detection circuit 30.

[0069] 1-3. Structure of the detection circuit

[0070] Figure 6 This is a diagram showing an example of the structure of the detection circuit 30. (As shown...) Figure 6 As shown, the detection circuit 30 includes charge amplifier circuits 31A and 31B, differential amplifier circuit 32, adder circuit 33, AC amplifier circuit 34A and 34B, synchronous detector circuit 35A and 35B, smoothing circuit 36A and 36B, variable amplifier circuit 37A and 37B, and filter circuits 38A and 38B.

[0071] A first signal is input to the charge amplifier circuit 31A via the S1 terminal. The first signal is an alternating charge generated by the detection electrode 114 of the physical quantity detection element 100, which includes a first physical quantity component based on the physical quantity detected by the physical quantity detection element 100 and a first vibration leakage component based on the vibration of the physical quantity detection element 100.

[0072] Additionally, a second signal is input to the charge amplifier circuit 31B via the S2 terminal. The second signal is an alternating charge generated at the detection electrode 115 of the physical quantity detection element 100, which includes a second physical quantity component based on the physical quantity detected by the physical quantity detection element 100 and a second vibration leakage component based on the vibration of the physical quantity detection element 100.

[0073] In this embodiment, such as Figure 4As shown, when an angular velocity is applied to the physical quantity detection element 100, the detection vibrating arm 102 with the detection electrode 114 and the detection vibrating arm 102 with the detection electrode 115 undergo bending vibrations in opposite directions to achieve balance. Therefore, the first physical quantity component and the second physical quantity component are out of phase. Here, the out-of-phase relationship between the first and second physical quantity components includes not only the case where the phase difference between the first and second physical quantity components is exactly 180°, but also the case where the phase difference between the first and second physical quantity components has a small error relative to 180° due to manufacturing errors of the physical quantity detection element 100, errors in the delay time of the signal propagation path, etc.

[0074] Furthermore, in this embodiment, the first vibration leakage component and the second vibration leakage component are in phase with each other. Here, the in-phase nature of the first and second vibration leakage components includes not only the case where the phase difference between the first and second vibration leakage components is exactly 0°, but also the case where the phase difference between the first and second vibration leakage components has a small error relative to 0° due to manufacturing errors of the physical quantity detection element 100, errors in the delay time of the signal propagation path, etc.

[0075] For example, the weights of the four weighting sections 103 are adjusted so that the vibration energy of the two driving vibration arms 101a and the two driving vibration arms 101b are equal, and a difference is generated between the sum of the vibration energy of the two driving vibration arms 101a and the sum of the vibration energy of the two driving vibration arms 101b. This allows the first vibration leakage component and the second vibration leakage component to be in phase with each other. Furthermore, the greater the difference between the sum of the vibration energy of the two driving vibration arms 101a and the sum of the vibration energy of the two driving vibration arms 101b, the greater the first and second vibration leakage components. The weight adjustment of the weighting section 103 is performed, for example, by irradiating the weighting section 103 with a laser and removing a portion of the weighting section 103.

[0076] Charge amplifier circuit 31A converts the first signal into an AC voltage signal based on the reference voltage Vref generated by reference voltage circuit 10 and outputs it. Charge amplifier circuit 31B converts the second signal into an AC voltage signal based on the reference voltage Vref and outputs it. In addition, charge amplifier circuit 31A is an example of "first charge amplifier circuit" and charge amplifier circuit 31B is an example of "second charge amplifier circuit".

[0077] The differential amplifier circuit 32 differentially amplifies the signal pair consisting of the output signal of the charge amplifier circuit 31A and the output signal of the charge amplifier circuit 31B. This signal pair is based on the first signal and the second signal. As described above, since the first physical quantity component and the second physical quantity component are out of phase, the physical quantity component is amplified by the differential amplifier circuit 32. On the other hand, since the first vibration leakage component and the second vibration leakage component are in phase, the vibration leakage component is attenuated by the differential amplifier circuit 32. Therefore, the influence of the vibration leakage component on the physical quantity component is reduced in the output signal of the differential amplifier circuit 32. Furthermore, in order to substantially eliminate the influence of the vibration leakage component on the physical quantity component in the output signal of the differential amplifier circuit 32, it is preferable that the difference between the first vibration leakage component and the second vibration leakage component is substantially zero. Furthermore, the fact that the difference between the first vibration leakage component and the second vibration leakage component is essentially zero means that it includes not only the case where the difference is exactly zero, but also the case where the difference has a small error relative to zero due to the minimum adjustment resolution of the first and second vibration leakage components, and the case where the measured value has a small error relative to zero due to the measurement error of the difference between the first and second vibration leakage components.

[0078] AC amplifier circuit 34A amplifies the output signal of differential amplifier circuit 32. The output signal of AC amplifier circuit 34A is input to synchronous detector circuit 35A.

[0079] The synchronous detection circuit 35A uses the output signal of the AC amplifier circuit 34A as the detected signal and performs synchronous detection using the detection signal SDET. This synchronous detection circuit 35A extracts the physical quantity components contained in the output signal of the AC amplifier circuit 34A. Specifically, the synchronous detection circuit 35A synchronously detects the signal based on the output signal of the differential amplifier circuit 32, i.e., the output signal of the AC amplifier circuit 34A, and outputs a signal corresponding to the difference between the first physical quantity component contained in the first signal and the second physical quantity component contained in the second signal. The synchronous detection circuit 35A can also be a switching circuit such that, for example, the output signal of the AC amplifier circuit 34A is selected when the voltage level of the detection signal SDET is higher than the reference voltage Vref, and the signal after inverting the output signal of the AC amplifier circuit 34A relative to the reference voltage Vref is selected when the voltage level of the detection signal SDET is lower than the reference voltage Vref. Furthermore, the synchronous detection circuit 35A is an example of a "first synchronous detection circuit".

[0080] The output signal of the synchronous detection circuit 35A is smoothed into a DC voltage signal by the smoothing circuit 36A and then input to the variable amplifier circuit 37A.

[0081] The variable amplifier circuit 37A amplifies or attenuates the output signal of the smoothing circuit 36A according to a set gain, thereby adjusting the detection sensitivity. The signal amplified or attenuated by the variable amplifier circuit 37A is then input to the filter circuit 38A.

[0082] The filter circuit 38A limits the output signal of the variable amplifier circuit 37A to the desired frequency band. The output signal of the filter circuit 38A is output from the detection circuit 30 as the physical quantity detection signal SAO.

[0083] In addition, the smoothing circuit 36A, the variable amplifier circuit 37A, the filter circuit 38A, the analog-to-digital conversion circuit 41, and the digital signal processing circuit 51 are circuits that generate physical quantity detection signals SDOX based on the output signal of the synchronous detection circuit 35A, and are an example of a "physical quantity detection signal generation circuit".

[0084] The adder circuit 33 adds the signal pairs consisting of the output signals of the charge amplifier circuit 31A and the charge amplifier circuit 31B. As described above, since the first physical quantity component and the second physical quantity component are out of phase, the adder circuit 33 attenuates the physical quantity component. On the other hand, since the first vibration leakage component and the second vibration leakage component are in phase, the adder circuit 33 amplifies the vibration leakage component.

[0085] AC amplifier circuit 34B amplifies the output signal of adder circuit 33. The output signal of AC amplifier circuit 34B is input to synchronous detector circuit 35B.

[0086] The synchronous detection circuit 35B uses the output signal of the AC amplifier circuit 34B as the detected signal and performs synchronous detection using the detection signal QDET. This synchronous detection circuit 35B extracts the vibration leakage component contained in the output signal of the AC amplifier circuit 34B. Specifically, the synchronous detection circuit 35B synchronously detects the signal based on the output signal of the adder circuit 33, i.e., the output signal of the AC amplifier circuit 34B, and outputs a signal corresponding to the sum of the first vibration leakage component contained in the first signal and the second vibration leakage component contained in the second signal. The synchronous detection circuit 35B can be, for example, a switching circuit that selects the output signal of the AC amplifier circuit 34B when the voltage level of the detection signal QDET is higher than the reference voltage Vref, and selects the signal after inverting the output signal of the AC amplifier circuit 34B relative to the reference voltage Vref when the voltage level of the detection signal QDET is lower than the reference voltage Vref. Furthermore, the synchronous detection circuit 35B is an example of a "second synchronous detection circuit".

[0087] The output signal of the synchronous detector circuit 35B is smoothed into a DC voltage signal by the smoothing circuit 36B and then input to the variable amplifier circuit 37B.

[0088] The variable amplifier circuit 37B amplifies or attenuates the output signal of the smoothing circuit 36B according to a set gain. The signal amplified or attenuated by the variable amplifier circuit 37B is then input to the filter circuit 38B.

[0089] The filter circuit 38B limits the output signal of the variable amplifier circuit 37B to the desired frequency band. The output signal of the filter circuit 38B is output from the detection circuit 30 as the vibration leakage signal QAO.

[0090] In addition, the smoothing circuit 36B, the variable amplifier circuit 37B, the filter circuit 38B, the analog-to-digital conversion circuit 42, and the digital signal processing circuit 52 are circuits that generate the vibration leakage signal QDOX based on the output signal of the synchronous detection circuit 35B, and are an example of a "vibration leakage signal generation circuit".

[0091] 1-4. Examples of signal waveforms

[0092] Figure 7 This is a diagram illustrating an example of the waveforms of various signals representing the physical quantity components contained in the alternating charge output from the physical quantity detection element 100. Figure 7 In, it is shown Figure 5 The waveforms of the signals from point A to point C shown are... Figure 6 The waveforms of the signals from point D to point K are shown. In each signal waveform, the horizontal axis represents time, and the vertical axis represents voltage. Additionally, Figure 7 This is an example of applying a certain angular velocity to the physical quantity detection element 100.

[0093] The signal at point A is the output signal of the current-to-voltage conversion circuit 21, which is a constant frequency signal centered on the reference voltage Vref.

[0094] The signal at point B is the output signal of AC amplifier circuit 22, namely the detector signal SDET, which is a square wave voltage signal that is in phase with the signal at point A and has a constant amplitude of Vc.

[0095] The signal at point C is the output signal of the phase shifting circuit 24, namely the detector signal QDET, which is a square wave voltage signal whose phase leads the signal at point B by 90° and whose amplitude is a constant value Vc.

[0096] The signal at point D is the first physical quantity component contained in the output signal of charge amplifier circuit 31A. It is a signal with the same phase as the signal at point A and a constant frequency centered on the reference voltage Vref.

[0097] The signal at point E is the second physical quantity component contained in the output signal of charge amplifier circuit 31B. It is a signal with a constant frequency centered on the reference voltage Vref, and is 180° out of phase with the signal at point A. The first physical quantity component contained in the signal at point D and the second physical quantity component contained in the signal at point E are out of phase with each other and have essentially the same amplitude.

[0098] The signal at point F is the signal after differential amplification of the physical quantity components contained in the output signal of AC amplifier circuit 34A, namely the first physical quantity component contained in the signal at point D and the second physical quantity component contained in the signal at point E. It is a signal with the same phase as the signal at point A and a constant frequency centered on the reference voltage Vref.

[0099] The signal at point G is the physical quantity component contained in the output signal of the synchronous detector circuit 35A, that is, the signal at point F that has undergone full-wave rectification with reference voltage Vref based on the physical quantity component contained in the signal at point B.

[0100] The signal at point H is the physical quantity component contained in the output signal of the filter circuit 38A, and is the signal of the voltage value V1 corresponding to the physical quantity detected by the physical quantity detection element 100.

[0101] The signal at point I is the physical quantity component contained in the output signal of AC amplifier circuit 34B, that is, the first physical quantity component contained in the signal at point D and the second physical quantity component contained in the signal at point E are added and amplified and almost removed. It is a signal with a voltage value of reference voltage Vref.

[0102] The signal at point J is the physical quantity component contained in the output signal of the synchronous detector circuit 35B, that is, the signal through point C is the signal containing the physical quantity component of the signal at point I after full-wave rectification with reference voltage Vref as the reference voltage, and it is a signal with a voltage value of reference voltage Vref.

[0103] The signal at point K is the physical quantity component contained in the output signal of filter circuit 38B, and its voltage value is the reference voltage Vref.

[0104] Figure 8 This is a diagram illustrating an example of waveforms for various signals related to the vibration leakage component contained in the alternating charge output from the physical quantity detection element 100. Figure 8 In, it is shown Figure 5 The waveforms of the signals from point A to point C shown are... Figure 6 The waveforms of the signals from point D to point K are shown. In the waveforms of each signal, the horizontal axis represents time and the vertical axis represents voltage.

[0105] exist Figure 8 In the diagram, the signals at points A, B, and C are... Figure 7 same.

[0106] The signal at point D is the first vibrational leakage component contained in the output signal of charge amplifier circuit 31A. It is a signal with a constant frequency that is 90° ahead of the signal at point A and centered on the reference voltage Vref.

[0107] The signal at point E is the second vibrational leakage component contained in the output signal of charge amplifier circuit 31B. It is a constant frequency signal with a phase leading the signal at point A by 90° and centered on the reference voltage Vref. The first vibrational leakage component contained in the signal at point D and the second vibrational leakage component contained in the signal at point E are in phase with each other and have substantially the same amplitude.

[0108] The signal at point F is the signal whose vibration leakage component, i.e. the first vibration leakage component contained in the signal at point D and the second vibration leakage component contained in the signal at point E, has been differentially amplified and almost removed. It is a signal with a voltage value of the reference voltage Vref.

[0109] The signal at point G is the vibration leakage component contained in the output signal of the synchronous detector circuit 35A. That is, the signal containing the vibration leakage component of the signal at point F is rectified by the signal at point B with reference voltage Vref as the reference voltage. It is a signal with a voltage value of reference voltage Vref.

[0110] The signal at point H is the vibration leakage component contained in the output signal of filter circuit 38A, and the signal has a voltage value of reference voltage Vref.

[0111] The signal at point I is the signal amplified by adding the vibration leakage component contained in the output signal of AC amplifier circuit 34B, namely the first vibration leakage component contained in the signal at point D and the second vibration leakage component contained in the signal at point E. It is a signal with a constant frequency that is 90° ahead of the signal at point A and centered on the reference voltage Vref.

[0112] The signal at point J is the vibration leakage component contained in the output signal of the synchronous detector circuit 35B, that is, the signal at point C is the vibration leakage component contained in the signal at point I that has been fully rectified by the reference voltage Vref.

[0113] The signal at point K is the vibration leakage component contained in the output signal of the filter circuit 38B, and is the signal of the voltage value V2 corresponding to the vibration leakage generated in the physical quantity detection element 100.

[0114] In fact, the signals from point D to point K are... Figure 7 The waveforms and Figure 8 The waveform is obtained by adding the waveforms together. Here, because... Figure 8 The signal at point H is a signal with a voltage value equal to the reference voltage Vref. Therefore, the output signal of the 38A filter circuit, i.e., the physical quantity detection signal SAO, contains almost no vibration leakage components. Figure 7 The signals at point H are roughly the same, corresponding to voltage levels and physical quantity components. Therefore, MCU 5 reads the physical quantity detection signal SDOX generated based on the physical quantity detection signal SAO, thereby enabling it to measure the physical quantity applied to physical quantity sensor 1.

[0115] In addition, due to Figure 7 The signal at point K is a signal with a voltage value equal to the reference voltage Vref. Therefore, the output signal of the filter circuit 38B, i.e., the vibration leakage signal QAO, contains almost no physical quantity components. Figure 8 The signals at point K are roughly consistent, corresponding to the voltage level and the vibration leakage component. Furthermore, if physical quantity sensor 1 is functioning normally, the voltage level of the vibration leakage signal QAO remains approximately constant. Therefore, the fault diagnosis circuit 60 can diagnose a fault in physical quantity sensor 1 if the magnitude of the vibration leakage signal QDOX generated based on the vibration leakage signal QAO differs from the first range.

[0116] 1-5. Steps in Fault Diagnosis Methods

[0117] Figure 9 This is a flowchart illustrating an example of the steps in a fault diagnosis method for the physical quantity sensor 1 according to this embodiment. Additionally, in Figure 9 In the flowchart, the processing of each step can also be changed appropriately.

[0118] like Figure 9 As shown, in the fault diagnosis method of the physical quantity sensor 1 in this embodiment, firstly, the charge amplifier circuits 31A and 31B of the physical quantity detection circuit 200 generate a signal pair based on a first signal and a second signal output from the physical quantity detection element 100 (step S1). Here, the first signal is a signal that includes a first physical quantity component based on the physical quantity detected by the physical quantity detection element 100 and a first vibration leakage component based on the vibration of the physical quantity detection element 100, and is input to the charge amplifier circuit 31A via the S1 terminal. The second signal is a signal that includes a second physical quantity component based on the physical quantity detected by the physical quantity detection element 100 and a second vibration leakage component based on the vibration of the physical quantity detection element 100, and is input to the charge amplifier circuit 31B via the S2 terminal. Furthermore, as... Figure 7 Like the signal at point D and point E, the first and second physical quantity components are out of phase. Additionally, as... Figure 8 The signals at point D and point E are similar, and the first and second vibration leakage components are in phase with each other.

[0119] Next, the differential amplifier circuit 32 of the physical quantity detection circuit 200 differentially amplifies the signal pair based on the first signal and the second signal generated in step S1 (step S2).

[0120] Next, the synchronous detection circuit 35A of the physical quantity detection circuit 200 synchronously detects the signal based on the signal obtained in step S2 to generate a signal corresponding to the difference between the first physical quantity component and the second physical quantity component (step S3).

[0121] Next, the physical quantity detection signal generation circuit of the physical quantity detection circuit 200 generates a physical quantity detection signal SDOX based on the signal generated in step S3 (step S4). Here, the physical quantity detection signal generation circuit is a circuit composed of a smoothing circuit 36A, a variable amplifier circuit 37A, a filter circuit 38A, an analog-to-digital conversion circuit 41, and a digital signal processing circuit 51.

[0122] In addition, the physical quantity detection circuit 200 performs the processes of steps S5, S6, S7 and S8 in parallel with the processes of steps S2, S3 and S4.

[0123] Specifically, firstly, the addition circuit 33 of the physical quantity detection circuit 200 adds the signal pair based on the first signal and the second signal generated in step S1 (step S5).

[0124] Next, the synchronous detection circuit 35B of the physical quantity detection circuit 200 synchronously detects the signal based on the signal obtained in step S5 to generate a signal corresponding to the sum of the first vibration leakage component and the second vibration leakage component (step S6).

[0125] Next, the vibration leakage signal generation circuit of the physical quantity detection circuit 200 generates a vibration leakage signal QDOX based on the signal generated in step S6 (step S7). Here, the vibration leakage signal generation circuit is a circuit composed of a smoothing circuit 36B, a variable amplification circuit 37B, a filtering circuit 38B, an analog-to-digital conversion circuit 42, and a digital signal processing circuit 52.

[0126] Next, the fault diagnosis circuit 60 of the physical quantity detection circuit 200 performs fault diagnosis of the physical quantity sensor 1 based on the vibration leakage signal QDOX generated in step S7 (step S8).

[0127] Then, the physical quantity detection circuit 200 repeatedly performs the processing steps S1 to S8.

[0128] in addition, Figure 9 Step S2 is an example of a "differential amplification step". Additionally, Figure 9Step S3 is an example of the "first synchronous detection step". Additionally, Figure 9 Step S4 is an example of the "physical quantity detection signal generation step". Additionally, Figure 9 Step S5 is an example of an "addition step". Additionally, Figure 9 Step S6 is an example of the "second synchronous detection step". Additionally, Figure 9 Step S7 is an example of the "vibration leakage signal generation step". Additionally, Figure 9 Step S8 is an example of a "fault diagnosis step".

[0129] 1-6. Effects

[0130] In the physical quantity sensor 1 of this embodiment, the physical quantity detection element 100 outputs a first signal and a second signal. The first signal includes a first physical quantity component based on the detected physical quantity and a first vibration leakage component based on the vibration of the physical quantity detection element 100. The second signal includes a second physical quantity component based on the detected physical quantity and a second vibration leakage component based on the vibration of the physical quantity detection element 100. Furthermore, the physical quantity detection circuit 200 includes: an adder circuit 33 that adds the signal pairs based on the first and second signals output from the physical quantity detection element 100; a synchronous detector circuit 35B that synchronously detects the signal based on the output signal of the adder circuit 33 and outputs a signal corresponding to the sum of the first and second vibration leakage components; and a vibration leakage signal generation circuit that generates a vibration leakage signal QDOX based on the output signal of the synchronous detector circuit 35B. Moreover, since the first and second vibration leakage components are in phase, the vibration leakage component is amplified by the adder circuit 33. Furthermore, for example, if a portion of the physical quantity detection element 100 is damaged, or if a portion of the wiring electrically connected to the physical quantity detection element 100 is cut or short-circuited, the magnitude of the first vibration leakage component or the second vibration leakage component will change, and therefore the magnitude of the vibration leakage signal QDOX will change. Therefore, according to the physical quantity sensor 1, the physical quantity detection circuit 200, or the fault diagnosis method of the physical quantity sensor 1 of this embodiment, a vibration leakage signal QDOX that can be used for fault diagnosis can be generated based on the leakage vibration generated in the physical quantity detection element 100.

[0131] Furthermore, in the physical quantity sensor 1 of this embodiment, the physical quantity detection circuit 200 includes: a differential amplifier circuit 32 that differentially amplifies a signal pair based on a first signal and a second signal output from the physical quantity detection element 100; a synchronous detection circuit 35A that synchronously detects a signal based on the output signal of the differential amplifier circuit 32 and outputs a signal corresponding to the difference between the first physical quantity component and the second physical quantity component; and a physical quantity detection signal generation circuit that generates a physical quantity detection signal SDOX based on the output signal of the synchronous detection circuit 35A. Moreover, since the first physical quantity component contained in the first signal and the second physical quantity component contained in the second signal are out of phase, the physical quantity components are amplified by the differential amplifier circuit 32. Furthermore, since the magnitudes of the first and second physical quantity components change according to the magnitude of the physical quantity detected by the physical quantity detection element 100, the magnitude of the physical quantity detection signal SDOX changes. Therefore, according to the physical quantity sensor 1, physical quantity detection circuit 200, or fault diagnosis method of physical quantity sensor 1 of this embodiment, a physical quantity detection signal SDOX corresponding to the physical quantity detected by physical quantity detection element 100 can be generated.

[0132] Furthermore, in the physical quantity sensor 1 of this embodiment, since the first vibration leakage component contained in the first signal and the second vibration leakage component contained in the second signal are in phase, the vibration leakage component is attenuated by the differential amplifier circuit 32. Therefore, even if the phase of the detection signal SDET input to the synchronous detection circuit 35A deviates from the design value due to manufacturing deviations, the vibration leakage component contained in the output signal of the synchronous detection circuit 35A is reduced, thereby reducing the possibility of an increase in the noise component contained in the physical quantity detection signal SDOX and the possibility of an uncertain amount of deviation of the zero point from the design value. Therefore, according to the physical quantity sensor 1, the physical quantity detection circuit 200, or the fault diagnosis method of the physical quantity sensor 1 of this embodiment, the influence of leakage vibration on the physical quantity detection signal SDOX can be reduced. In particular, if the physical quantity detection element 100 is adjusted so that the difference between the first vibration leakage component and the second vibration leakage component is substantially zero, the vibration leakage component contained in the output signal of the differential amplifier circuit 32 is substantially zero. Therefore, even if the phase of the detection signal SDET deviates from the design value, the output signal of the synchronous detection circuit 35A contains almost no vibration leakage component, and hardly any leakage vibration affects the physical quantity detection signal SDOX.

[0133] Furthermore, in the physical quantity sensor 1 of this embodiment, since the first physical quantity component contained in the first signal and the second physical quantity component contained in the second signal are out of phase, the physical quantity component is attenuated by the adder circuit 33. Therefore, even if the phase of the detection signal QDET input to the synchronous detection circuit 35B deviates from the design value due to manufacturing deviations, the physical quantity component contained in the output signal of the synchronous detection circuit 35B is reduced, thus reducing the possibility of an increase in the noise component contained in the vibration leakage signal QDOX. Therefore, according to the physical quantity sensor 1, the physical quantity detection circuit 200, or the fault diagnosis method of the physical quantity sensor 1 of this embodiment, the influence of the detected physical quantity on the vibration leakage signal QDOX can be reduced, and fault diagnosis can be performed continuously in parallel with the detection of physical quantities.

[0134] Furthermore, in the physical quantity sensor 1 of this embodiment, the physical quantity detection circuit 200 includes a fault diagnosis circuit 60, which performs fault diagnosis based on the vibration leakage signal. Moreover, the fault diagnosis circuit 60 diagnoses a fault if the magnitude of the vibration leakage signal QDOX is not included in the first range. Therefore, according to the physical quantity sensor 1, the physical quantity detection circuit 200, or the fault diagnosis method of the physical quantity sensor 1 of this embodiment, since the MCU 5, as an external device, does not need to perform fault diagnosis, the processing load of the MCU 5 can be reduced. Furthermore, if the first range is variable, an appropriate first range corresponding to the magnitudes of the first and second vibration leakage components can be set, thus reducing the possibility of false diagnosis by the fault diagnosis circuit 60. Alternatively, without changing the design of the physical quantity detection circuit 200, any one of the various physical quantity detection elements 100 with different magnitudes of the first and second vibration leakage components can be connected to the physical quantity detection circuit 200.

[0135] 1-7. Variations

[0136] For example, in the above embodiment, the physical quantity detection circuit 200 includes a fault diagnosis circuit 60, but it may not include a fault diagnosis circuit. For example, the MCU 5, as an external device, can also perform fault diagnosis of the physical quantity sensor 1 based on the vibration leakage signal QDOX.

[0137] Furthermore, in the above embodiment, the physical quantity detection circuit 200 outputs the physical quantity detection signal SDOX and the fault diagnosis result signal QF to the MCU 5 via the interface circuit 70 according to the request from the external device, i.e., the MCU 5. However, the fault diagnosis result signal QF can also be output independently of the physical quantity detection signal SDOX via the interface circuit 70. Alternatively, the physical quantity detection circuit 200 can output the fault diagnosis result signal QF via an external terminal without going through the interface circuit 70.

[0138] In addition, in the above embodiment, the physical quantity detection circuit 200 outputs the physical quantity detection signal SDOX and the vibration leakage signal QDOX as digital signals via the interface circuit 70, but it can also output the physical quantity detection signal and the vibration leakage signal as analog signals via external terminals.

[0139] In addition, in the above embodiment, the analog-to-digital conversion circuit 41 converts the physical quantity detection signal SAO into the physical quantity detection signal SDO, and the analog-to-digital conversion circuit 42 converts the vibration leakage signal QAO into the vibration leakage signal QDO. However, it is also possible that one analog-to-digital conversion circuit performs the processing of converting the physical quantity detection signal SAO into the physical quantity detection signal SDO and the processing of converting the vibration leakage signal QAO into the vibration leakage signal QDO in a time-division manner.

[0140] In addition, in the above embodiment, the digital signal processing circuit 51 performs a prescribed operation on the physical quantity detection signal SDO to generate the physical quantity detection signal SDOX, and the digital signal processing circuit 52 performs a prescribed operation on the vibration leakage signal QDO to generate the vibration leakage signal QDOX. However, it is also possible that one digital signal processing circuit performs the processing of generating the physical quantity detection signal SDOX and the processing of generating the vibration leakage signal QDOX in a time-division manner.

[0141] Furthermore, in the above embodiment, the physical quantity sensor 1 includes a physical quantity detection element 100 that detects angular velocity as a physical quantity, but it may also include a physical quantity detection element that detects physical quantities other than angular velocity. For example, the physical quantity sensor 1 may also include a physical quantity detection element that detects physical quantities such as acceleration, angular acceleration, velocity, and force.

[0142] Furthermore, in the above embodiments, the physical quantity sensor 1 includes one physical quantity detection element, but it may also include multiple physical quantity detection elements. For example, the physical quantity sensor 1 may include multiple physical quantity detection elements, each of which uses any one of two or more mutually perpendicular axes as the detection axis to detect the physical quantity. Alternatively, for example, the physical quantity sensor 1 may include multiple physical quantity detection elements, each of which detects any one of various physical quantities such as angular velocity, acceleration, angular acceleration, velocity, and force. That is, the physical quantity sensor 1 may also be a composite sensor.

[0143] Furthermore, in the above embodiment, the example given is a double-T type quartz oscillator for the physical quantity detection element 100. However, the oscillator of the physical quantity detection element for detecting various physical quantities can be, for example, a tuning fork type or a comb type, or a prism, square prism, cylindrical, or other similar shapes. Additionally, the material of the oscillator for the physical quantity detection element can be different from quartz (SiO2). For example, piezoelectric single crystals such as lithium tantalate (LiTaO3) and lithium niobate (LiNbO3), piezoelectric ceramics such as lead zirconate titanate (PZT), and silicon semiconductors can also be used. Furthermore, the oscillator of the physical quantity detection element can also be constructed by distributing a piezoelectric thin film such as zinc oxide (ZnO) or aluminum nitride (AlN) sandwiched between driving electrodes on a portion of the surface of the silicon semiconductor. For example, the physical quantity detection element can be a MEMS (Micro Electromechanical Systems) element.

[0144] Furthermore, while the above embodiment exemplifies a piezoelectric physical quantity sensing element, physical quantity sensing elements for detecting various physical quantities are not limited to piezoelectric elements; they can also be electrostatic capacitive, electrodynamic, eddy current, optical, strain gauge, or other types of elements. Additionally, the detection method of the physical quantity sensing element is not limited to vibration-based methods; for example, it can also be optical, rotational, or fluid-based methods.

[0145] 2. Electronic equipment

[0146] Figure 10 This is a functional block diagram illustrating an example of the structure of the electronic device according to this embodiment. For example... Figure 10 As shown, the electronic device 300 of this embodiment includes a physical quantity sensor 310, a processing circuit 320, an operation unit 330, a ROM (Read Only Memory) 340, a RAM (Random Access Memory) 350, a communication unit 360, and a display unit 370. Furthermore, the electronic device of this embodiment may also be configured with omissions or modifications. Figure 10 It is a component of or has other components added to it.

[0147] The physical quantity sensor 310 detects a physical quantity and outputs the detection result to the processing circuit 320. For example, the physical quantity sensor 1 of this embodiment described above can be used as the physical quantity sensor 310.

[0148] The processing circuit 320 processes the output signal from the physical quantity sensor 310. Specifically, the processing circuit 320 communicates with the physical quantity sensor 310 according to a program stored in the ROM 340, etc., and uses the output signal from the physical quantity sensor 310 to perform various calculations and control processes. In addition, the processing circuit 320 also performs various processes corresponding to operation signals from the operation unit 330, controls the communication unit 360 to communicate with external devices, and sends display signals to the display unit 370 to display various information.

[0149] The operation unit 330 is an input device consisting of operation keys, push-button switches, etc., which outputs operation signals corresponding to the user's operation to the processing circuit 320.

[0150] ROM 340 stores programs / data for the processing circuit 320 to perform various calculations and control processes.

[0151] RAM 350 is used as the working area of ​​processing circuit 320, temporarily storing programs / data read from ROM 340, data input from operation unit 330, and the results of calculations performed by processing circuit 320 according to various programs.

[0152] The communication unit 360 performs various controls for establishing data communication between the processing circuit 320 and external devices.

[0153] The display unit 370 is a display device composed of an LCD (Liquid Crystal Display) or the like, which displays various information based on display signals input from the processing circuit 320. A touch panel that functions as an operation unit 330 may also be provided on the display unit 370.

[0154] By using the physical quantity sensor 1 of this embodiment as the physical quantity sensor 310, a signal that can be used for fault diagnosis can be generated based on the leakage vibration generated in the physical quantity detection element, and the influence of leakage vibration on the physical quantity detection signal can be reduced. Therefore, for example, a highly reliable electronic device can be realized.

[0155] As such electronic device 300, various electronic devices can be considered, such as personal computers (mobile / laptop / tablet type), mobile terminals such as smartphones / mobile phones, digital cameras, inkjet printers and other inkjet output devices, storage area network devices such as routers / switches, local area network devices, mobile terminal base station equipment, televisions, video cameras, video recorders, car navigation devices, real-time clock devices, pagers, electronic notebooks, electronic dictionaries, calculators, video game devices, game controllers, word processors, workstations, video phones, security television monitors, electronic telescopes, POS terminals, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasound diagnostic devices, medical devices such as electronic endoscopes, fish detectors, various measuring devices, measuring instruments for vehicles / aircraft / ships, flight simulators, head-mounted displays, motion trackers, motion trackers, motion controllers, Pedestrian Dead Reckoning (PDR) devices, etc.

[0156] Figure 11 This is a perspective view schematically showing a digital camera 1300, an example of the electronic device 300 in this embodiment. Additionally, in Figure 11 The diagram also briefly illustrates the connection to external devices. Here, while a conventional camera uses the light image of the subject to expose silver halide photographic film, the digital camera 1300 uses an imaging element such as a CCD (Charge Coupled Device) to perform photoelectric conversion on the light image of the subject, generating an image signal.

[0157] A display unit 1310 is provided on the back of the housing 1302 of the digital camera 1300. This display unit employs a structure that displays the image signal from the CCD, functioning as a viewfinder that displays the subject as an electronic image. Furthermore, a light-receiving unit 1304, including an optical lens and a CCD, is provided on the front side of the housing 1302. When the photographer confirms the image of the subject displayed on the display unit 1310 and presses the shutter button 1306, the image signal from the CCD at that moment is transmitted / saved into the memory 1308. Additionally, in this digital camera 1300, a video signal output terminal 1312 and a data communication input / output terminal 1314 are provided on the side of the housing 1302. The video signal output terminal 1312 is connected to a television monitor 1430, and the data communication input / output terminal 1314 is connected to a personal computer 1440, as needed. Furthermore, the following structure is adopted: the camera signal stored in the memory 1308 is output to the television monitor 1430 and the personal computer 1440 using a prescribed operation. The digital camera 1300 has, for example, a physical quantity sensor 310 as an angular velocity sensor, and the output signal of the physical quantity sensor 310 is used for processing such as hand shake correction.

[0158] 3. Moving objects

[0159] Figure 12 This is a diagram illustrating an example of the movable body of this embodiment. Figure 12 The mobile body 400 shown includes a physical quantity sensor 410, processing circuits 440, 450, and 460, a battery 470, and a navigation device 480. Alternatively, the mobile body in this embodiment may be configured to omit these components. Figure 12 It is a component of or has other components added to it.

[0160] The physical quantity sensor 410, processing circuits 440, 450, 460, and navigation device 480 operate using the power supply voltage provided by the battery 470.

[0161] The physical quantity sensor 410 detects physical quantities and outputs the detection results to the processing circuits 440, 450, and 460.

[0162] Processing circuits 440, 450, and 460 process the output signal from physical quantity sensor 410. For example, processing circuits 440, 450, and 460 use the output signal from physical quantity sensor 410 to perform various controls on the posture control system, anti-rollover system, braking system, etc.

[0163] The navigation device 480 displays the position, time, and other information of the moving body 400 on a display screen based on the output information of its built-in GPS receiver. Furthermore, even when GPS signals are not received, the navigation device 480 determines the position and orientation of the moving body 400 based on the output signal of the physical quantity sensor 410 and continues to display the necessary information.

[0164] For example, by using the physical quantity sensor 1 of each of the above embodiments as the physical quantity sensor 410, a signal that can be used for fault diagnosis can be generated based on the leakage vibration generated in the physical quantity detection element, and the influence of leakage vibration on the physical quantity detection signal can be reduced. Therefore, for example, a mobile body with high reliability can be realized.

[0165] As such a mobile body 400, various mobile bodies can be considered, such as cars such as electric cars, airplanes such as jet planes or helicopters, ships, rockets, artificial satellites, etc.

[0166] The above-described embodiments and modifications are examples only and are not limited thereto. For example, various embodiments and modifications can be appropriately combined.

[0167] This invention includes structures that are substantially the same as those described in the embodiments (e.g., structures with the same function, method, and result, or structures with the same purpose and effect). Furthermore, this invention includes structures obtained by replacing non-essential parts of the structures described in the embodiments. Furthermore, this invention includes structures capable of achieving the same function or effect as the structures described in the embodiments, or achieving the same purpose. Furthermore, this invention includes structures obtained by adding known techniques to the structures described in the embodiments.

Claims

1. A physical quantity detection circuit, comprising: The driving circuit generates a driving signal to excite the physical quantity detection element to vibrate, and generates a first detection signal with the same phase as the driving signal and a second detection signal with a phase 90° different from the driving signal. A differential amplifier circuit that differentially amplifies a signal pair based on a first signal and a second signal output from the physical quantity detection element; The first synchronous detection circuit uses the first detection signal to synchronously detect the signal based on the output signal of the differential amplifier circuit as the detected signal. A physical quantity detection signal generation circuit generates a physical quantity detection signal based on the output signal of the first synchronous detection circuit. An adder circuit that adds the signal pairs; A second synchronous detection circuit uses the second detection signal to synchronously detect a signal based on the output signal of the adder circuit as the detected signal; and The vibration leakage signal generation circuit generates a vibration leakage signal based on the output signal of the second synchronous detection circuit.

2. The physical quantity detection circuit according to claim 1, wherein, The physical quantity detection circuit includes a fault diagnosis circuit, which performs fault diagnosis based on the vibration leakage signal.

3. The physical quantity detection circuit according to claim 2, wherein, The physical quantity detection circuit includes: A first charge amplifier circuit, which is input to the first signal; and The second charge amplifier circuit is input to the second signal. The signal pair is a signal pair consisting of the output signal of the first charge amplifier circuit and the output signal of the second charge amplifier circuit.

4. The physical quantity detection circuit according to claim 3, wherein, The vibration leakage signal generation circuit includes a smoothing circuit, which smooths the output signal of the second synchronous detection circuit to output a DC voltage signal.

5. The physical quantity detection circuit according to claim 4, wherein, The vibration leakage signal generation circuit includes a variable amplifier circuit, which amplifies or attenuates the DC voltage signal before outputting it.

6. The physical quantity detection circuit according to claim 5, wherein, The vibration leakage signal generation circuit includes a filtering circuit that outputs the vibration leakage signal by limiting the output signal of the variable amplifier circuit to a desired frequency band.

7. The physical quantity detection circuit according to claim 6, wherein, The first signal contains a first vibration leakage component. The second signal contains a second vibration leakage component.

8. The physical quantity detection circuit according to claim 7, wherein, The first vibration leakage component and the second vibration leakage component are in phase with each other.

9. The physical quantity detection circuit according to claim 8, wherein, The vibration leakage signal is an analog signal. The vibration leakage signal generation circuit includes an analog-to-digital conversion circuit, which converts the vibration leakage signal into a digital signal and then outputs it.

10. A physical quantity sensor, comprising: The physical quantity detection circuit according to any one of claims 1 to 9; and Physical quantity detection element.

11. An electronic device comprising: The physical quantity sensor according to claim 10; Storage department; and The processing circuit processes the data based on the output signal of the physical quantity sensor and the data stored in the storage unit.

12. A mobile body comprising: The physical quantity sensor according to claim 10; Processing circuitry that controls attitude based on the output signal of the physical quantity sensor; and A navigation device that determines its position based on the output signal of the physical quantity sensor.

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