Gyroscope sensor

Abstract

The gyroscope sensor has PLL circuits (110, 120), and has first demodulation units (113, 123) that demodulate a first drive signal and a detection signal (VXP) of a first vibration mode based on a resonance frequency ([omega] 1), and demodulate a second drive signal and a detection signal (VYP) of a second vibration mode based on a resonance frequency ([omega] 2). The control unit (10) has second demodulation units (114, 124) that perform demodulation on the basis of the detection signal and the second drive signal, and demodulation on the basis of the detection signal and the first drive signal. The control unit has a demodulation output calculation unit (130, 140) for performing a calculation based on the demodulation output of the first and second demodulation units, and performs feedback control for matching the oscillation axis of the oscillator (2) with the electrode axis when the voltage is applied on the basis of the calculation result of the demodulation output calculation unit.

Description

Technical Field

[0001] The present disclosure relates to a gyro sensor. Background Art

[0002] Currently, in a vibratory gyro sensor, by making the resonance frequencies of two vibration modes that excite an oscillator as a sensor element coincide, that is, by mode matching, the accuracy of the sensor can be improved. Generally, as long as the oscillator is not subjected to special processing for adjusting the vibration mode, the vibration axis and the electrode axis are different, or the two resonance frequencies ω1 and ω2 are different. Hereinafter, for ease of explanation, the resonance frequency of the first vibration mode of the oscillator will be simply referred to as "resonance frequency ω1", and the resonance frequency of the second vibration mode of the oscillator will be simply referred to as "resonance frequency ω2". In addition, in this specification, the two resonance frequencies ω1 and ω2 of the oscillator may sometimes be collectively referred to as "mode frequencies ω1 and ω2".

[0003] Therefore, in order to improve the accuracy of the sensor, in the case of electrostatic drive, mode matching utilizes the electro-spring effect and uses the electrostatic force generated by applying a voltage to adjust the state of the vibration mode, so that the mode frequencies ω1 and ω2 (ω2 > ω1) coincide. Hereinafter, for ease of explanation, the angle formed by the vibration axis and the electrode axis of the oscillator will be referred to as θ ωα , the frequency difference of the mode frequencies will be referred to as Δω α , the angles formed by the vibration axis and the electrode axis when applying a voltage when driving the oscillator and the difference in mode frequencies will be referred to as θ ωβ , Δω β .

[0004] As a gyro sensor for always maintaining the above mode matching, for example, the gyro sensor described in Patent Document 1 can be cited. The gyro sensor described in Patent Document 1 includes a first PLL circuit and a second PLL circuit. The first PLL circuit performs frequency control of a drive signal for vibrating the oscillator in the first vibration mode, and the second PLL circuit performs frequency control of a drive signal for vibrating the oscillator in the second vibration mode. This gyro sensor performs control in mode matching so that the two resonance frequencies ω1 and ω2 of the oscillator respectively become a reference frequency ω ref . In addition, PLL is an abbreviation for Phase Locked Loop and is also called a phase-locked loop.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Chinese Patent Application Publication No. 115597574 Specification Summary of the Invention

[0008] In Patent Document 1, a gyro sensor having two PLL circuits and always maintaining mode matching is proposed. However, in order to satisfy the two conditions of ω2 - ω1 = Δω α = 0 and θ ωα = 0, special processing for adjusting the vibration mode or careful voltage application is required in advance. However, in the case of a sensor element where Δω α ≠ 0 and θ ωα ≠ 0 in the initial state without special processing or the like, in order to always maintain mode matching, it is necessary to control θ β independently of Δω ωβ .

[0009] In view of the above problems, an object of the present disclosure is to provide a gyro sensor that can perform feedback control of θ α during voltage application of the vibration mode independently of the control of Δω ωα even when Δω β ≠ 0 and θ ωβ ≠ 0 in the initial state.

[0010] According to one aspect of the present disclosure, a gyro sensor includes: an oscillator having a first vibration mode and a second vibration mode with different resonance frequencies; a mounting substrate having a plurality of electrodes opposed to the oscillator; a first PLL circuit that controls the frequency of a drive signal for causing the oscillator to vibrate in the first vibration mode; a second PLL circuit that controls the frequency of a drive signal for causing the oscillator to vibrate in the second vibration mode; a first demodulation unit that defines a radial direction with an imaginary straight line passing through the center of the region surrounded by the plurality of electrodes and along the thickness direction of the mounting substrate as an axis, sets two directions as electrode axes in the radial direction along the drive electrodes for driving the first vibration mode and the second vibration mode among the plurality of electrodes, and sets two directions along the vibration directions of the first vibration mode and the second vibration mode as vibration axes, and the first demodulation unit calculates a first demodulation output based on a first detection signal from the electrodes that detect the vibration of the first vibration mode among the plurality of electrodes and a first drive signal having a resonance drive frequency in the first vibration mode output from the first PLL circuit, and calculates a second demodulation output based on a second detection signal from the electrodes that detect the vibration of the second vibration mode among the plurality of electrodes and a second drive signal having a resonance drive frequency in the second vibration mode output from the second PLL circuit; a second demodulation unit that calculates a third demodulation output based on the first detection signal and the second drive signal, and calculates a fourth demodulation output based on the second detection signal and the first drive signal; a first demodulation output calculation unit that calculates the amplitude and phase of the first vibration mode based on the first demodulation output and the third demodulation output; a second demodulation output calculation unit that calculates the amplitude and phase of the second vibration mode based on the second demodulation output and the fourth demodulation output; and a control circuit that outputs a control signal for aligning the vibration axis with the electrode axis based on an input signal regarding the amplitude and phase from the first demodulation output calculation unit or the second demodulation output calculation unit.

[0011] Thus, the gyro sensor has two independent PLL circuits and a first demodulation unit that demodulates based on the first detection signal of the first vibration mode of the oscillator and its first drive signal, and demodulates based on the second detection signal of the second vibration mode of the oscillator and its second drive signal. In addition, the gyro sensor has a second demodulation unit that demodulates based on the first detection signal and the second drive signal, and demodulates based on the second detection signal and the first drive signal. Further, the gyro sensor includes a demodulation output calculation unit and a control circuit. The demodulation output calculation unit calculates the amplitude and phase of the two vibration modes based on the demodulation outputs of the first and second demodulation units, and the control circuit outputs a control signal for aligning the vibration axis of the oscillator with the electrode axis based on the input signal from the demodulation output calculation unit.

[0012] Thus, in the gyro sensor, even in the initial state, the difference Δω between the two resonance frequencies of the oscillator αθ that is not equal to 0 and where the vibration axis is offset from the electrode axis ωα Even when it is not equal to 0, feedback control where θ = 0 can also be performed based on the two demodulation units and their demodulation outputs. ωβ Description of the Drawings

[0013] Figure 1 It is a perspective view showing a structural example of the sensor element.

[0014] Figure 2 It shows Figure 1 a cross-sectional view of the cross-sectional structure at the II-II line of

[0015] Figure 3 It corresponds to Figure 2 a drawing of

[0016] Figure 4 It is an explanatory drawing regarding the vibration axis and the electrode axis of the sensor element.

[0017] Figure 5 It is a drawing showing a two-dimensional vibration model of the oscillator of the gyro sensor.

[0018] Figure 6 It is an explanatory drawing regarding the types of applied voltages applied to the constituent electrodes of the gyro sensor.

[0019] Figure 7 It is a block diagram showing the structure of the gyro sensor of the first embodiment.

[0020] Figure 8 It is an explanatory drawing regarding the demodulation unit and the demodulation output calculation unit in the gyro sensor of the first embodiment.

[0021] Figure 9 It is an explanatory drawing regarding the first vibration mode and the second vibration mode in the oscillator vibrating in the wine glass mode.

[0022] Figure 10 It is an explanatory drawing regarding the demodulation output.

[0023] Figure 11 It is a drawing showing the relationship between the demodulation output, the output waveform, and the ω polarity of θ.

[0024] Figure 12 It is a block diagram showing a modified example of the gyro sensor of the first embodiment.

[0025] Figure 13 It is a block diagram showing the structure of the gyro sensor of the second embodiment.

[0026] Figure 14 ​It is an explanatory diagram of a demodulation unit and a demodulation output calculation unit in a gyro sensor according to a second embodiment.

[0027] Figure 15 It is a perspective view showing another structural example of a sensor element. Specific Embodiments

[0028] Hereinafter, embodiments of the present disclosure will be described based on the drawings. In addition, in the following respective embodiments, the same or equivalent parts are denoted by the same reference numerals for description.

[0029] (First Embodiment)

[0030] The gyro sensor 1 according to the first embodiment will be described with reference to the drawings.

[0031] [Basic Structure]

[0032] For example, as Figure 1 shown, the gyro sensor 1 according to the present embodiment includes a sensor element having a vibrator 2 and a mounting substrate 3, and the vibrator 2 is mounted on the mounting substrate 3. The gyro sensor 1 can detect the angular velocity and rotation angle applied to the gyro sensor 1 based on changes in the electrostatic capacitance between a part of the thin-walled vibrator 2 that can vibrate in the first vibration mode and the second vibration mode and a plurality of first electrode portions 51 in the mounting substrate 3. The gyro sensor 1 can always perform mode matching control by a control unit 10 described later.

[0033] For example, as Figure 2 shown, the vibrator 2 is a minute vibrating body having a three-dimensional substantially symmetric structure including a curved surface portion 21 and a mounting portion 22. The curved surface portion 21 includes an outer shape of a substantially hemispherical three-dimensional curved surface, and the mounting portion 22 extends from the vertex side of the imaginary hemisphere formed by the curved surface portion 21 toward the center side of the hemisphere. The vibrator 2 is formed with conductive films (not shown) on, for example, both the front and back surfaces, and a voltage can be applied from the mounting substrate 3. In the vibrator 2, for example, an edge 23 on the side of the curved surface portion 21 opposite to the mounting portion 22 faces a plurality of first electrode portions 51, and the edge 23 vibrates in a resonance mode by an electrostatic force generated between the first electrode portions 51 and the edge 23.

[0034] In addition, the vibrator 2 can be manufactured, for example, by preparing a plate made of any reflow soldering material such as quartz and a mold having a bowl-shaped recess and a pillar portion located at the center of the recess, placing the plate in the mold, and heating and softening it while reducing the pressure in the recess.

[0035] In addition, for example, as Figure 3As shown, the vibrator 2 may also have a substantially disc shape with a disc-shaped portion and a columnar connection portion that joins to the mounting substrate 3 at the center of this portion. In this case, the end at the disc-shaped portion in the hollow state of the vibrator 2 is the edge 23, and this portion is surrounded by a plurality of first electrode portions 51. Thus, the vibrator 2 only needs to be a structure that can vibrate in the first vibration mode and the second vibration mode by the drive electrodes among the plurality of first electrode portions 51. In addition to the above structure, it may also be other known structures.

[0036] For example, as Figure 1 and Figure 2 shown, the mounting substrate 3 includes a lower substrate 4 and an upper substrate 5, and is a structure formed by joining them. For example, the mounting substrate 3 is obtained by performing wiring film formation, etc. on the lower substrate 4 made of borosilicate glass, an insulating material, then anodically joining the upper substrate 5 made of silicon, a semiconductor material, to the lower substrate 4, and performing patterning. The mounting substrate 3 forms a plurality of first electrode portions 51 and second electrode portions 52, for example, by performing dry etching such as DRIE on the upper substrate 5 after anodic bonding. DRIE is an abbreviation for Deep Reactive Ion Etching. In addition, the mounting substrate 3, for example, in the case where the vibrator 2 is in the Figure 2 shown birdbath shape, may also form an unillustrated circular groove along the edge 23 on the lower substrate 4 as needed so as not to contact the edge 23.

[0037] The plurality of first electrode portions 51, for example, face the edge 23 of the vibrator 2 and are arranged at equal intervals from each other in a manner of depicting a ring on the plane of the mounting substrate. The plurality of first electrode portions 51 each form an unillustrated electrode film on the upper surface. The plurality of first electrode portions 51 can control their potentials, for example, by connecting unillustrated wires to the unillustrated electrode films and electrically connecting them to an external circuit board or the like. The plurality of first electrode portions 51 are all in a state of being separated from the edge 23 of the vibrator 2 by a predetermined distance, and each form a capacitor with the vibrator 2, and can detect the electrostatic capacitance with the vibrator 2. A part of the plurality of first electrode portions 51 is a detection electrode for detecting the electrostatic capacitance, and the other part is a drive electrode for applying an electrostatic force to the edge 23 of the vibrator 2.

[0038] For example, as Figure 1 shown, the second electrode portion 52 has a frame shape surrounding the plurality of first electrode portions 51, forms an unillustrated electrode film on the upper surface, and connects an unillustrated wire to the unillustrated electrode film. The second electrode portion 52 is connected to an unillustrated conductive film of the vibrator 2 through unillustrated wiring or the like and is configured to be able to apply a voltage.

[0039] The above is the basic structure of the sensor part in the gyro sensor 1 of this embodiment. The control unit 10 that performs the drive control of the gyro sensor 1 will be described later.

[0040] In addition, in Figure 1 , as a representative example, a case where the mounting substrate 3 has 16 first electrode portions 51 and one frame-shaped second electrode portion 52 is shown, but it is not limited thereto. For example, the number, arrangement, shape, etc. of the first electrode portion 51 and the second electrode portion 52 can be appropriately changed on the mounting substrate 3.

[0041] [Vibration model and various voltages of the first electrode portion]

[0042] Next, with reference to Figures 4 - 6 , the vibration model of the oscillator 2 and various voltages at the plurality of first electrode portions 51 will be described. In Figure 6 , the plurality of first electrode portions 51 are shown in a state of observing the mounting substrate 3 from above, and the outer contour of the edge 23 of the oscillator 2 is represented by a double-dot chain line.

[0043] When the oscillator 2 is observed from the normal direction with respect to the plane direction formed by the mounting substrate 3 (hereinafter referred to as "observing from above"), by applying a voltage to a part of the first electrode portion 51, for example, as Figure 4 shown, it becomes a resonant state in which the number of antinodes and nodes of the vibration amplitude of the outer contour of the edge 23 is 2n each. n is an integer of 2 or more, and such a resonant state of the oscillator 2 is called a "wine-glass mode". In addition, in Figure 4 , the state shown as a representative example is the resonant mode with n = 2 in the wine-glass mode, and the vibration axes x and y and the electrode axes X and Y described later coincide, but the oscillator 2 can also vibrate in a higher-order wine-glass mode with n = 3 or more.

[0044] Hereinafter, for the sake of convenience of explanation, as Figure 4 shown, with the center position of the edge 23 at the time of observing from above as the center C, the radial direction with respect to the imaginary straight line along the thickness direction of the mounting substrate 3 passing through the center C is called the "substrate radial direction", and the circumferential direction with respect to this imaginary straight line is called the "substrate circumferential direction". In addition, the direction passing through the position of the antinode of the vibration at the edge 23 of the oscillator 2 in the first vibration mode (resonant frequency ω1) in the direction along the substrate radial direction is called the "vibration axis x", and the direction passing through the position of the node is called the "vibration axis y". At this time, in the wine-glass mode with n = k (k: an integer of 2 or more), the angle formed by the vibration axis x and the vibration axis y is (360 / 4k)°. For example, in the wine-glass mode with n = 2, the angle formed by the vibration axis x and the vibration axis y is 45°.

[0045] A plurality of first electrode portions 51 are arranged, for example, separated from each other along the circumferential direction of the substrate, and are arranged in such a manner that the distances from the edge 23 in the non-vibrating state are substantially the same. Here, for the sake of convenience of explanation, for example, as Figure 4 shown, one direction on the actual plane where the plurality of first electrode portions 51 are arranged is set as "X r direction", and the direction orthogonal to the X r direction on this plane is set as "Y r direction", and this plane is set as "X r Y r plane". Moreover, one direction on the X r Y r plane is defined as "electrode axis X", and the direction towards which the electrode axis X rotates counterclockwise by (360 / 4k)° along the circumferential direction of the substrate on the X r Y r plane is defined as "electrode axis Y".

[0046] For example, as Figure 5 shown, the oscillator 2 has a mass point MP and springs S arranged along the vibration axes x and y, and can be regarded as a vibrating body of a two-degree-of-freedom system vibrating in a two-dimensional plane. Figure 5 What is shown represents the conversion of the vibration axes x and y and the electrode axes X and Y on the X r Y r plane into an orthogonal coordinate system respectively, and making the origins of the vibration axes x and y and the electrode axes X and Y coincide. Generally, for a sensor element formed by mounting the oscillator 2 on the mounting substrate 3, as long as no special processing or the like is performed, the electrode axes X and Y and the vibration axes x and y are different, that is, the vibration axes and the electrode axes do not overlap. That is, if the Figure 5 angles formed by the electrode axes X and Y and the vibration axes x and y in the orthogonal coordinate system shown are set as θ ω , then the sensor element is generally θ ω ≠0.

[0047] In addition, the vibration axes x and y of the oscillator 2 respectively correspond to the vibration directions of the first vibration mode and the second vibration mode with different modal frequencies ω1 and ω2. That is, as long as no special processing or the like is performed on the sensor element, the difference Δω between the modal frequencies ω1 and ω2 (>ω1) is generally not zero, Δω≠0. The gyro sensor 1 performs modal matching control by the control unit 10 described later in order to improve the sensor accuracy.

[0048] Here, Figure 5 shown, the equation of motion of the vibration model of the two-degree-of-freedom system is expressed by the following equation (1) in the case of the wine glass mode with n = 2.

[0049]

Mathematical formula 1

[0050]

[0051] The V in equation (1) XT , V YT , V Q+ , V Q－ are various voltages applied to the first electrode portion 51 respectively. V XT , V YT , V Q+ , V Q－ and other various voltages applied to the first electrode portion 51 will be described later.

[0052] The τ in equation (1) is the time constant, θ τ is the angle formed by the damping axis and the electrode axis, Ω is the angular velocity input to the sensor element, ω is the resonance angular frequency of the oscillator 2, F x , F y are the forces acting on the oscillator in the X and Y directions of the electrode axis. Specifically, ω1 and ω2 in equation (1) are the resonance frequencies in the x and y directions of the vibration axis before the application of the voltage, ω = (ω1 2 + ω2 2 ) / 2, ωΔω = (ω1 2 -ω2 2 ) / 2. Regarding the time constant τ, the equations 1 / τ = {(1 / τ1) + (1 / τ2)} / 2, Δ(1 / τ) = (1 / τ1) - (1 / τ2) hold. τ1 and τ2 are the decay time constants in the x and y directions of the vibration axis before the application of the voltage. In addition, λ in equation (1) is a conversion coefficient depending on the oscillator 2 and the electrode shape for converting the applied voltage into the effect of an electric spring.

[0053] In addition, the modal frequencies ω1 and ω2 of the oscillator 2 are represented by the following equation (2).

[0054] The ω in equation (2) 1，2 2 are the resonance frequencies in the x and y directions of the vibration axis when the voltage is applied.

[0055]

Mathematical formula 2

[0056]

[0057] For example, according to the non-patent literature Yi.Zhou, IEEE SENSORS JOURNAL, VOL.21, NO.24, December 15, 2021, modal matching corresponds to the control in which the first and second terms of the square root in equation (2) are zero at the modal frequency.

[0058] In addition, if the angle formed by the electrode axes X and Y and the vibration axes x and y of the oscillator 2 when voltages are applied to a plurality of first electrode portions 51 is set as θωβ Let the modal frequency difference be Δω β , then the modal matching corresponds to θ ωβ = 0 and Δω β = 0 control.

[0059] The control unit 10 controls to the above-mentioned θ ωβ = 0 and Δω β = 0. For example, as Figure 6 shown, various voltages are applied to and detected from the plurality of first electrode portions 51. The applied voltage and the detected voltage of the plurality of first electrode portions 51 are, for example, V XD , V XT , V XP , V YD , V YT , V YP , V Q+ , V Q－ . The detected voltage is also referred to as a detection signal or a detected voltage signal. The detection signal is not limited to being a voltage and can also be a current. In other words, the detection signal can also be a voltage / current signal. Specifically, it can also be a digital signal obtained by converting a voltage / current.

[0060] V XD Based on the signals output from the PLL circuit 120 and the AGC circuit 121 described later, it is a drive voltage for resonantly driving the oscillator 2 in the first vibration mode at the resonance frequency ω1. V XT is output from the PI circuit 122 described later and is used to control the resonance frequency ω1 of the first vibration mode by relaxing the spring S of the oscillator 2 in the electrode axis X direction by utilizing the electro-spring effect so that Δω β = 0 applied voltage. V XP is the first detected voltage of the vibration of the oscillator 2 on the electrode axis X. V XD , V XT , V XP correspond to, for example, the electrode portions located on the electrode axis X among the plurality of first electrode portions 51.

[0061] V YD Based on the signals output from the PLL circuit 110 and the AGC circuit 111 described later, it is a drive voltage for resonantly driving the oscillator 2 in the second vibration mode at the resonance frequency ω2. V YT is output from the PI circuit 112 described later and is used to control the resonance frequency ω2 of the second vibration mode by relaxing the spring S of the oscillator 2 in the electrode axis Y direction by utilizing the electro-spring effect so that Δω β = 0 applied voltage. V YP is the second detected voltage of the vibration of the oscillator 2 on the electrode axis Y and is output from the first electrode portion 51 disposed on the vibration axis x. V YD, V YT , V YP For example, it corresponds to the electrode portion among the plurality of first electrode portions 51 that is located on the electrode axis Y.

[0062] In addition, V XT , V YT Is applied to a part of the plurality of first electrode portions 51 for performing mode matching to make the difference between the two mode frequencies of the oscillator 2 zero, and at least one of them is controlled by the control unit 10. Specifically, in mode matching, when the control unit 10 makes one of the two mode frequencies ω1 and ω2 of the oscillator 2 (for example, ω2) match the lower frequency (for example, ω1), it controls one of the applied V XT , V YT . On the other hand, when the control unit 10 performs mode matching to make the two mode frequencies ω1 and ω2 of the oscillator 2 match the specified reference frequency ω ref , it controls both of the applied V XT , V YT . Regarding whether to control one of the applied V XT , V YT or both, it can be appropriately designed, and either one is acceptable.

[0063] V Q+ , V Q－ Is a control voltage for making the vibration axes x and y coincide with the electrode axes X and Y to make θ ωβ = 0, and is applied to, for example, the electrode portions of the first electrode portion 51 that are not on the electrode axes X and Y. For example, as Figure 5 shows, V Q+ is the control voltage when the vibration axes x and y rotate clockwise when viewed from above. V Q－ is the control voltage when the vibration axes x and y rotate counterclockwise when viewed from above. V Q+ , V Q－ are both applied to any one of the first electrode portions 51, and one of them is controlled according to the direction of the offset between the vibration axes x and y and the electrode axes X and Y, so that the vibration axes x and y rotate in the direction opposite to the offset direction.

[0064] [Control Unit]

[0065] Next, the control unit 10 of the gyro sensor 1 will be described.

[0066] Hereinafter, for the sake of convenience of explanation, as Figure 7 shows, the one composed of Figure 1The sensor element composed of the oscillator 2 and the mounting substrate 3 shown and a circuit (not shown) for applying a voltage to a plurality of first electrode portions 51 are collectively referred to as the "sensor unit". As the circuit (not shown) mentioned here, for example, a current-voltage conversion circuit, a DAC, an ADC, etc. can be cited. In addition, in Figure 6 In order to facilitate observation, V Q+ and V Q－ are collectively labeled as "V Q ". Figure 7 The voltages V XD and V XT and V YD and V YT and V Q applied to the sensor unit in XP and the detection voltages V YP from the sensor unit are voltages corresponding to various voltages of the above-mentioned first electrode portion 51.

[0067] The control unit 10 is, for example, an electronic control unit that mounts various electronic devices such as a CPU, a ROM, and a RAM on a circuit board (not shown) and executes drive control of the gyro sensor 1. CPU is an abbreviation for Central Processing Unit, ROM is an abbreviation for Read Only Memory, and RAM is an abbreviation for Random Access Memory. For example, as Figure 7 shown, the control unit 10 includes two PLL circuits 110, 120, two AGC circuits 111, 121, two PI circuits 112, 122, and two first demodulation units 113, 123. AGC is an abbreviation for Automatic Gain Control and is also referred to as automatic gain control. PI is an abbreviation for Proportional Integral.

[0068] The PLL circuit 110, the AGC circuit 111, the PI circuit 112, and the first demodulation unit 113, for example, execute control of the resonance frequency ω1 and the amplitude of one of the two vibration modes of the oscillator 2. The PLL circuit 120, the AGC circuit 121, the PI circuit 122, and the first demodulation unit 123 execute control of the resonance frequency ω2 and the amplitude in the remaining one of the vibration modes of the oscillator 2.

[0069] The PLL circuit 110, for example, has an oscillation circuit (not shown) that generates a drive signal of a specified frequency and executes frequency control of the drive signal to resonantly drive the oscillator 2 at the resonance frequency ω1. The PLL circuit 110 is based on the detection voltage V XPAn input signal of phase information regarding the first vibration mode obtained by demodulation is subjected to the above frequency control. The AGC circuit 111 controls the amplitude of the first vibration mode of the oscillator 2 based on, for example, the input signal from the first demodulation unit 113. The PI circuit 112 adjusts the resonance frequency ω1 of the first vibration mode of the oscillator 2 based on, for example, the output signal of the PLL circuit 110 and controls it to Δω β = 0. The first demodulation unit 113 is input, for example, with the detection voltage V XP and the output signal from the PLL circuit 110 and performs demodulation corresponding to the resonance frequency ω1. The first demodulation unit 113 obtains, for example, information on the phase φ1 and amplitude R1 of the detection signal corresponding to the first vibration mode through demodulation, feeds back the information on the phase φ1 to the PLL circuit 110, and feeds back the information on the amplitude R1 to the AGC circuit 111. The first demodulation unit 113 outputs, for example, the demodulation output corresponding to the resonance frequency ω1 to the first demodulation output arithmetic unit 130 described later.

[0070] In addition, the PLL circuit 120, AGC circuit 121, PI circuit 122, and first demodulation unit 123 perform the same processing as the PLL circuit 110, AGC circuit 111, PI circuit 112, and first demodulation unit 113, respectively, corresponding to the second vibration mode and resonance frequency ω2 of the oscillator 2. The PLL circuit 120 has, for example, an oscillation circuit (not shown) and performs frequency control of the drive signal based on the input signal from the first demodulation unit 123 in order to drive the oscillator 2 in the second vibration mode with the resonance frequency ω2. The first demodulation unit 123 obtains information on the phase φ2 and amplitude R2 of the detection signal corresponding to the second vibration mode through demodulation, feeds back the information on the phase φ2 to the PLL circuit 120, and feeds back the information on the amplitude R2 to the AGC circuit 121. Also, the first demodulation unit 123 outputs, for example, the demodulation output corresponding to the resonance frequency ω2 to the second demodulation output arithmetic unit 140 described later. Further, the control unit 10 outputs, for example, signals V Ω+ 、V Ω－ .

[0071] The control unit 10 further has, for example, two second demodulation units 114, 124, a first demodulation output arithmetic unit 130, a second demodulation output arithmetic unit 140, and a control circuit 150.

[0072] The second demodulation unit 114 obtains information on the resonance frequency ω2 of the second vibration mode based on the drive signal output from the second PLL circuit 120 and performs demodulation corresponding to the resonance frequency ω2 based on the detection voltage V XP of the first vibration mode. In a system where the modal frequencies ω1 and ω2 of the oscillator 2 are maintained in resonance drive by two independent PLL circuits 110 and 120, the detection voltage VXP It contains information on the vibration amplitude in the y - direction of the vibration axis of the second vibration mode, so this is achievable. The second demodulation unit 114 inputs the demodulation output to the first demodulation output operation unit 130.

[0073] The second demodulation unit 124 obtains information on the resonance frequency ω1 of the first vibration mode based on the drive signal output from the first PLL circuit 110, and based on the detection voltage V of the second vibration mode YP performs demodulation corresponding to the resonance frequency ω1. Similar to the above, because the detection voltage V YP contains information on the vibration amplitude in the x - direction of the vibration axis of the first vibration mode, this demodulation is achievable. The second demodulation unit 124 inputs the demodulation output to the second demodulation output operation unit 140.

[0074] The first demodulation output operation unit 130 is based on the demodulation outputs V XP obtained by demodulating the detection voltage V by the first demodulation unit 113 and the second demodulation unit 114 Xi1 、V Xq1 、V Xi2 、V Xq2 and performs an operation for controlling to θ ωβ = 0. For example, as Figure 8 shown, the first demodulation output operation unit 130 includes a plurality of HPFs 131 - 134, phase comparison units 135, 136, and operation units 137, 138, and obtains the necessary operation and phase difference information for controlling to θ ωβ = 0. HPF is an abbreviation for High Pass Filter, and for example, any high - pass filter such as a DC - cut filter is used. The phase comparison units 135, 136, for example, use phase comparators and output signals corresponding to the phase difference between the two input signals. The results of various operations performed by the first demodulation output operation unit 130 are, for example, output to the control circuit 150.

[0075] The second demodulation output operation unit 140 is based on the demodulation outputs V YP obtained by demodulating the detection voltage V by the first demodulation unit 123 and the second demodulation unit 124 Yi1 、V Yq1 、V Yi2 、V Yq2 and performs an operation for controlling to θ ωβ = 0. The second demodulation output operation unit 140, for example, includes a plurality of HPFs 141 - 144, phase comparison units 145, 146, and operation units 147, 148, and obtains the necessary operation and phase difference information for controlling to θ ωβNecessary operations and information on the phase difference. The results of various operations performed by the second demodulation output operation unit 140 are output to the control circuit 150, for example. HPF141 to 144, phase comparison units 145 and 146, and operation units 147 and 148 have the same structure as HPF131 to 134, phase comparison units 135 and 136, and operation units 137 and 138, respectively.

[0076] In addition, regarding the demodulation outputs V Xi1 、V Xq1 、V Xi2 、V Xq2 、V Yi1 、V Yq1 、V Yi2 、V Yq2 and the operations in the demodulation output operation units 130 and 140 will be described later.

[0077] Based on the operation results in the demodulation output operation units 130 and 140, the control circuit 150 calculates the voltage V Q as a control signal for making θ ωβ = 0, outputs V Q + and V Q－ to the sensor unit, and controls one of V Q + and V Q－ . The control circuit 150 is, for example, a PI circuit.

[0078] The above is the basic structure of the control unit 10. The control unit 10 performs the control of Δω β = 0 through the PLL circuits 110 and 120, the AGC circuits 111 and 121, and the PI circuits 112 and 122, and performs the control of θ ωβ = 0 through the second demodulation units 114 and 124, the demodulation output operation units 130 and 140, and the control circuit 150. That is, the control unit 10 independently forms a control loop for Δω β = 0 and a control loop for θ ωβ = 0, and in mode matching, can perform the control of θ β = 0 in parallel with the control of Δω β = 0 and independently of the control of Δω ωβ = 0. Thus, the gyro sensor 1 is configured such that even in the initial state where θ ω ≠0 and Δω≠0, the two independent controls of θ ωβ = 0 and Δω β = 0 will act appropriately, and the mode matching control of Δω β = 0 can be performed.

[0079] In addition, the control unit 10 can also output various voltages V to the sensor unit, for example.XT , V XD , V YT , V YD , V Q + or V Q－ The circuit of Q－ has a DAC (not shown) as required. DAC is an abbreviation for Digital to Analog Converter. The control unit 10 can also, for example, cause the circuit for detecting the detection voltages V XP , V YP to have an ADC (not shown) as required. ADC is an abbreviation for Analog to Digital Converter.

[0080] [Operations in the demodulation unit]

[0081] Next, the arithmetic processing in the demodulation units 114, 124 and the demodulation output arithmetic units 130, 140 will be described. Here, the case of n = 2 in the wine glass mode is taken as a representative example for description. The cases of higher orders of n = 3 and above are basically the same, so their descriptions are omitted.

[0082] When the oscillator 2 is resonantly driven in both the first and second vibration modes of the resonant mode of n = 2, for example, as Figure 9 shown, it vibrates along two orthogonal vibration axes x and y. Also, let the vibration amplitude and modal frequency on the vibration axis x be A and ω1 respectively, the vibration amplitude and modal frequency on the vibration axis y be B and ω2 respectively, and the angle formed by the vibration axis x and the electrode axis X be θ ω . At this time, the vibration amplitudes of the vibration axes x and y at time t are represented by the following equations (3) and (4).

[0083] x = Asin(ω1t + φ1) ··· (3)

[0084] y = Bsin(ω2t + φ2) ··· (4)

[0085] φ1 in equation (3) and φ2 in equation (4) are the phases with respect to the external forces applied from each direction. If the components of the vibration with amplitude A on the electrode axes X and Y are set as a X , a Y , and the components of the vibration with amplitude B on the electrode axes X and Y are set as b X , b Y , then the offset angle θ ω between the vibration axis x and the electrode axis X is represented by the following equation (5) according to the orthogonality of the vibration axes x and y.

[0086] [Mathematical formula 3]

[0087]

[0088] In addition, the conversion between the electrode axes X and Y and the vibration axes x and y is represented by the following equation (6).

[0089]

Mathematical formula 4

[0090]

[0091] In addition, since the sum of the X components of the two vibration modes is on the electrode axis X and the sum of the Y components of the two vibration modes is on the electrode axis Y, the vibration amplitudes at time t of the electrode axes X and Y are represented by the following equations (7) and (8).

[0092] X = a X sin(ω1t + φ1) + b X sin(ω2t + φ2) ··· (7)

[0093] Y = a Y sin(ω1t + φ1) + b Y sin(ω2t + φ2) ··· (8)

[0094] In addition, in the example shown in Figure 9 , each component a X , b X , a Y , b Y in equations (7) and (8) are respectively a X = Acosθ ω , b X = -Bsinθ ω , a Y = Asinθ ω , b Y = Bcosθ ω . In addition, if the conversion coefficients from the amplitude to the voltage corresponding to the detection method are set as ξ X , ξ Y , then the voltages V XP , V YP on the detection electrodes of the electrode axes X and Y respectively are represented by the following equations (9) and (10).

[0095] V XP = ξ X {a X sin(ω1t + φ1) + b X sin(ω2t + φ2)} ··· (9)

[0096] V YP = ξ Y {a Y sin(ω1t + φ1) + b Ysin(ω2t + φ2)} ···(10)

[0097] The first demodulation unit 113 demodulates and outputs V for the external forces on the vibration axes x and y based on the voltage V in Equation (9). XP , and performs operations on the demodulation outputs V Xi1 and V Xq1 . The demodulation outputs V Xi1 and V Xq1 are respectively calculated based on the detection voltage V XP . They are the demodulation output in phase with the drive signal at the resonance frequency ω1 and the demodulation output in quadrature with the drive signal. The demodulation output V Xi1 is calculated by multiplying the voltage V XP by sinω1t as shown in Equation (11) below, and then eliminating the terms of the second harmonic and the sum of frequencies through a low-pass filter as shown in Equation (12).

[0098]

Mathematical Formula 5

[0099]

[0100]

Mathematical Formula 6

[0101] V Xi1 = |2V XP sinω1t| LPF

[0102] = ξ X {a X cosφ1 + b X (cosφ2cosΔωt - sinφ2sinΔωt)}

[0103] = ξ X {a X cosφ1 + b X cos(Δωt + φ2)}…(12)

[0104] |f(t)| in Equation (12) LPF refers to the operation of eliminating the terms of the second harmonic and the sum of frequencies through the low-pass filter as described above. The same applies to Equations (14), (16), and (18) later.

[0105] The demodulation output V Xq1 is calculated by multiplying the voltage V XP by cosω1t as shown in Equation (13) below, and then eliminating the unwanted terms through a low-pass filter as shown in Equation (14).

[0106]

Mathematical Formula 7

[0107]

[0108]

Mathematical formula 8

[0109] V Xq1 =[2V XP cosω1t| LPF

[0110] =ξ X {a X sinφ1+b X (cosφ2sinΔωt+sinφ2cosΔωt)}

[0111] =ξ X {a X sinφ1+b X sin(Δωt+φ2)}…(14)

[0112] The second demodulation unit 114 demodulates and outputs V XP , which is the demodulation output for the external forces on the vibration axes x and y, based on the voltage V of equation (9). Xi2 、V Xq2 of the operation. The demodulation outputs V Xi2 、V Xq2 are respectively calculated based on the detection voltage V XP , and are the demodulation output in phase with the drive signal of the resonance frequency ω2 and the demodulation output in quadrature with the drive signal. The second demodulation unit 114, for example, obtains from the second PLL circuit 120 a drive signal that resonantly drives the oscillator 2 at the resonance frequency ω2, and performs the operation of the demodulation outputs V Xi2 、V Xq2 . The demodulation output V Xi2 is calculated by multiplying the voltage V XP by sin(ω2t + Δφ) as shown in the following equation (15), and then eliminating unnecessary terms through a low-pass filter as shown in equation (16). In addition, Δφ is the phase of the output signal of the oscillator (not shown) in the PLL circuit 120 with respect to the output signal of the oscillator (not shown) in the PLL circuit 110 as a reference.

[0113] V XP sin(ω2t+Δφ)=ξ X {a X sin(ω1t+φ1)+b X sin(ω2t+φ2)}sin(ω2t+Δφ)···(15)

[0114]

Mathematical formula 9

[0115] VXi2 = |2V XP sin(ω2t + Δφ)| LPF

[0116] = ξ X {b X cos(φ2 - Δφ) + a X cos(Δωt - φ1 + Δφ)}…(16)

[0117] Demodulation output V Xq2 By performing a process of multiplying the voltage V as shown in Equation (17) below, and through an operation of eliminating unnecessary terms by a low-pass filter as shown in Equation (18). XP It is calculated by multiplying the voltage V by cos(ω2t + Δφ) and then performing an operation of eliminating unnecessary terms through a low-pass filter as shown in Equation (18).

[0118] V XP cos(ω2t + Δφ) = ξ X {a X sin(ω1t + φ1) + b X sin(ω2t + φ2)}cos(ω2t + Δφ) ···(17)

[0119]

Mathematical formula 10

[0120] V Xq2 = |2V XP cos(ω2t + Δφ)| LPF

[0121] = ξ X {b X sin(φ2 - Δφ) + a X sin(Δωt - φ1 + Δφ)}…(18)

[0122] The first demodulation unit 123 performs an operation on the demodulation outputs V YP for the external forces on the vibration axes x and y based on the detected voltage V in Equation (10). Yi2 , V Yq2 The second demodulation unit 124, for example, obtains a drive signal that resonantly drives the oscillator 2 at the resonance frequency ω1 from the first PLL circuit 110 and performs an operation on the demodulation outputs V Yi1 , V Yq1 The demodulation outputs V Yi2 , V Yq2 perform operations respectively based on the detected voltage V YP and are the demodulation outputs in phase (In Phase e ) with the drive signal at the resonance frequency ω2 and the demodulation outputs in quadrature phase with this drive signal. The demodulation outputs V Yi1 , V Yq1Based on the detection voltage V respectively YP Perform operations, which are demodulation outputs in phase with the drive signal of the resonance frequency ω1 and demodulation outputs in quadrature phase with the drive signal. Based on the detection voltage V YP The demodulation output V Yi1 、V Yq1 、V Yi2 、V Yq2 For example, as Figure 10 shown, through the same arithmetic processing as the above V Xi1 、V Xq1 、V Xi2 、V Xq2 to calculate. When φ1 = φ2 = Δφ = 0 is satisfied, these demodulation outputs can be transformed into mathematical expressions without the terms of φ1, φ2, and Δφ.

[0123] In addition, hereinafter, for the sake of convenience of explanation, the demodulation outputs V Xi1 、V Xq1 operated by the first demodulation unit 113 are sometimes referred to as "first demodulation outputs", and the demodulation outputs V Yi2 、V Yq2 operated by the first demodulation unit 123 are referred to as "second demodulation outputs". In addition, the demodulation outputs V Xi2 、V Xq2 operated by the second demodulation unit 114 are sometimes referred to as "third demodulation outputs", and the demodulation outputs V Yi1 、V Yq1 operated by the second demodulation unit 124 are referred to as "fourth demodulation outputs". The control unit 10 is configured such that the first demodulation output operation unit 130 performs operations based on the first demodulation output and the third demodulation output, and the second demodulation output operation unit 140 performs operations based on the second demodulation output and the fourth demodulation output.

[0124] Here, the angle θ formed by the vibration axes x, y and the electrode axes X, Y ω can be calculated by the following equation (19) or (20).

[0125]

Mathematical formula 11

[0126]

[0127]

Mathematical formula 12

[0128]

[0129] When C X 、C Y in the equations (19) and (20) are collectively referred to as C k , C k is represented by the following equation (21).

[0130] C k = |ξ k 2 a k b k | (k = X, Y)…(21)

[0131] Based on the demodulation outputs calculated by the demodulation units 113, 114, 123, and 124, the control unit 10 applies control voltages V Q+ , V Q－ , and simultaneously controls one of them such that |θ ω | = 0 as represented by Equation (19) or (20). |θ ω | = 0 means, from Equation (19) and (20), that |ξ Y a Y | = 0 or |ξ X b X | = 0. For example, as Figure 8 shown, the first demodulation output calculation unit 130 calculates the sum of squares by squaring and adding the demodulation outputs V Xi1 , V Xq1 respectively when φ1 = φ2 = Δφ = 0 using the calculation unit 137, and calculates the value of |ξ X b X |. The second demodulation output calculation unit 140 calculates the sum of squares by squaring and adding the demodulation outputs V Yi2 , V Yq2 respectively when φ1 = φ2 = Δφ = 0 using the calculation unit 147, and calculates the value of |ξ Y b Y |. These calculation results are output to the control circuit 150, for example, for the feedback control of |ξ Y a Y | = 0 or |ξ X b X | = 0, that is, |θ ω | = 0.

[0132] In addition, in the feedback control of |θ ω | = 0, for example, when aligning the vibration axes x, y with the electrode axes X, Y, both control voltages V Q+ , V Q－ are applied, and one of them is controlled according to the direction in which the vibration axes x, y are to be rotated. Specifically, the control voltage of V Q+ is controlled when the vibration axes x, y are rotated counterclockwise, and the control voltage of V Q－ is controlled when the vibration axes x, y are rotated clockwise. For example, as Figure 9 shown, when the vibration axes x, y are offset counterclockwise by an angle θ with respect to the electrode axes X, Yω In the case of, the control circuit 150 controls the applied control voltage V Q+ , V Q－ in which the vibration axes x and y of the vibrator 2 rotate clockwise. Q－ The control voltage.

[0133] The demodulation output arithmetic units 130 and 140 calculate the direction in which the vibration axes x and y rotate during the feedback control with |θ ω | = 0. Specifically, the first demodulation output arithmetic unit 130 calculates Δφ Xq1 using the phase comparison unit 135 based on the demodulation output V Xq2 after passing through the HPF 131 and the demodulation output V Xq . In addition, the first demodulation output arithmetic unit 130 calculates Δφ Xi1 using the phase comparison unit 136 based on the demodulation output V Xi2 after passing through the HPF 132 and the demodulation output V Xi . Similarly, the second demodulation output arithmetic unit 140 calculates Δφ Yq1 using the phase comparison unit 146 based on the demodulation output V Yq2 after passing through the HPF 144 and the demodulation output V Yq after passing through the HPF 142. In addition, the second demodulation output arithmetic unit 140 calculates Δφ Yi1 using the phase comparison unit 145 based on the demodulation output V Yi2 after passing through the HPF 143 and the demodulation output V Yi .

[0134] Then, for example, as Figure 11 shown, the control circuit 150 determines whether the output waveforms of the demodulation outputs V Xi , V Xq and the output waveforms of the demodulation outputs V Yi , V Yq are in-phase or out-of-phase based on the calculated phase difference. The control circuit 150 determines the polarity of θ ω , that is, in which direction the vibration axes x and y are shifted clockwise or counterclockwise with respect to the electrode axes X and Y. In addition, Figure 11 in, the polarity "+" of θ ω means the case where the vibration axis is shifted counterclockwise with respect to the electrode axis, and the polarity "-" of θ ω means the case where the vibration axis is shifted clockwise with respect to the electrode axis. The control circuit 150 determines one of the control targets in the output control voltages V ω , V Q+ , V Q－ according to the polarity of θ Q+, V Q－ , while controlling the one determined to be the control object.

[0135] In this way, the control unit 10 is configured such that when the sensor unit is in the initial state and θ ωα ≠0 and Δω α ≠0, it can perform feedback control of θ β =0 that is independent of the control when Δω ωβ =0 based on the demodulation outputs from the second demodulation units 114 and 124.

[0136] According to the present embodiment, the gyro sensor 1 has two independent PLL circuits 110 and 120 for maintaining the oscillator 2 through resonance driving in the first vibration mode and the second vibration mode, and includes first demodulation units 113 and 123 and second demodulation units 114 and 124. The first demodulation units 113 and 123 respectively calculate the detection voltage of the first vibration mode based on the resonance frequency ω1 and the demodulation outputs V Xi1 , V Xq1 of the first drive signal, the detection voltage of the second vibration mode based on the resonance frequency ω2 and the demodulation outputs V Yi2 , V Xq2 . The second demodulation units 114 and 124 respectively calculate the demodulation outputs V Xi2 , V Xq2 based on the detection voltage of the first vibration mode and the second drive signal, and the demodulation outputs V Yi1 , V Xq1 based on the detection voltage of the second vibration mode and the first drive signal. Moreover, the gyro sensor 1 is configured to be able to calculate, through the demodulation output calculation units 130 and 140, the control voltages V ωβ for controlling |θ Q+ | = 0 based on these demodulation outputs, and feed them back to the sensor unit through the control circuit 150. Therefore, the gyro sensor 1 has two PLL circuits 110 and 120, the first demodulation units 113 and 123, and the second demodulation units 114 and 124, and thus can perform feedback control of |θ Q－ | = 0 independently of the mode matching control when Δω β = 0. Therefore, even when using a sensor unit with θ ωβ ≠0 and Δω≠0 in the initial state, the gyro sensor 1 can perform control that always maintains mode matching without performing special processing or the like on the sensor unit. ω ≠0 and Δω≠0, it can perform control that always maintains mode matching without performing special processing or the like on the sensor unit.

[0137] (Modification Example of the First Embodiment)

[0138] For example, as Figure 12As shown, the gyro sensor 1 can also be implemented by replacing the two PI circuits 112 and 122 with a PI circuit 151 to perform Δω β =0 modal matching control structure.

[0139] In this case, the control unit 10 does not include the PI circuits 112 and 122, but instead uses the PI circuit 151 to control the applied voltage V XT 、V YT The PI circuit 151 inputs a signal corresponding to the operation result from the demodulation output operation unit 130, 140, and outputs a voltage that changes one of the modal frequencies ω1 and ω2 based on the amplitude information and phase information obtained by the operation, so that Δω β =0. The PI circuit 151 converts the voltage V XT 、V YT One of them is output to the sensor unit, so that |ξ Y b Y |=0 or |ξ X a X |=0. When the modal frequency ω1>ω2, the PI circuit 151 outputs a voltage V YT , so that |ξ Y b Y |=0, when the modal frequency ω1<ω2, the output voltage V XT , so that |ξ X a X |=0, perform Δω β =0 mode matching control.

[0140] According to this modification, the gyro sensor 1 can also obtain the same effects as those of the above-mentioned first embodiment.

[0141] (Second Embodiment)

[0142] Reference Figure 13 , Figure 14 A gyro sensor 1 according to a second embodiment will be described. Figure 14 In the figure, for ease of understanding, feedback from the first demodulation unit 113 to the PLL circuit 110 and the AGC circuit 111 and feedback from the first demodulation unit 123 to the PLL circuit 120 and the AGC circuit 121 are omitted.

[0143] For example Figure 13 As shown in FIG. 1 , the gyro sensor 1 of the present embodiment is different from the first embodiment described above in that the configuration of the control unit 10 is changed. In the present embodiment, this difference will be mainly described.

[0144] In this embodiment, for example, Figure 13As shown, the control unit 10 is configured to further include an oscillation circuit 160, and signals from the oscillation circuit 160 are input to the demodulation output arithmetic units 130 and 140. The oscillation circuit 160 calculates the difference Δω between two resonance frequencies ω1 and ω2, for example, based on the drive signals output from the two PLL circuits 110 and 120. Then, the oscillation circuit 160 outputs frequency signals with a frequency of Δω to the demodulation output arithmetic units 130 and 140 respectively.

[0145] In the present embodiment, for example, as Figure 14 shown, the first demodulation output arithmetic unit 130 includes a plurality of third demodulation units 139 that respectively perform demodulation processing on the demodulation outputs from the demodulation units 113 and 114, and phase comparison units 135 and 136. In addition, in Figure 14 , for ease of observation, only the signal input from the oscillation circuit 160 to one of the plurality of third demodulation units 139 and 149 is shown, and the signal input to other third demodulation units is omitted.

[0146] The plurality of third demodulation units 139 calculate |ξ Xi1 , V Xq1 , V Xi2 , V Xq2 and the frequency signal of Δω input from the oscillation circuit 160, and calculate the amplitude information |ξ X a X |, |ξ X b X | and the phase information φ Xi1 , φ Xq1 , φ Xi2 , φ Xq2 . The phase comparison unit 135 calculates the phase difference Δφ Xi1 , φ Xi2 based on the phase information φ Xi from the third demodulation unit 139, for example. The phase comparison unit 136 calculates the phase difference Δφ Xq1 , φ Xq2 based on the phase information φ Xq from the third demodulation unit 139, for example.

[0147] In the present embodiment, the second demodulation output arithmetic unit 140 includes a plurality of third demodulation units 149 that respectively perform demodulation processing on the demodulation outputs from the demodulation units 123 and 124, and phase comparison units 145 and 146.

[0148] The plurality of third demodulation units 149 calculate |ξ Yi1 , V Yq1 , V Yi2 , V Yq2 and the frequency signal of Δω input from the oscillation circuit 160, and calculate the amplitude information of |ξY a Y |, |ξ Y b Y | and phase information φ Yi1 , φ Yq1 , φ Yi2 , φ Yq2 . The phase comparison unit 145, for example, calculates the phase difference Δφ based on the phase information φ from the third demodulation unit 149 Yi1 , φ Yi2 Calculate the phase difference Δφ Yi . The phase comparison unit 146, for example, calculates the phase difference Δφ based on the phase information φ from the third demodulation unit 149 Yq1 , φ Yq2 Calculate the phase difference Δφ Yq .

[0149] The amplitude information and phase information obtained by the operations in the demodulation output operation units 130 and 140 are output to the control circuit 150 for feedback control with θ = 0, which is the same as in the first embodiment above ωβ = 0.

[0150] According to this embodiment, the gyro sensor 1 can also achieve the same effect as in the first embodiment above

[0151] (Other embodiments)

[0152] The present disclosure has been described based on the embodiments, but it should be understood that the present disclosure is not limited to these embodiments or structures. The present invention also includes various modifications and modifications within the equivalent scope. Moreover, various combinations, methods, and other combinations and methods that include only one of them, more elements, or fewer elements also fall within the scope and spirit of the present disclosure

[0153] In the above embodiment, a structural example in which a substrate such as silicon is divided by etching, and a first electrode portion 51 is formed by a plurality of opposing portions that are separated from each other and oppose the edge 23 and an electrode film (not shown) that covers the upper surface of the opposing portions has been described, but it is not limited thereto. For example, as Figure 15As shown, the sensor element may also form a substantially hemispherical recess 53 on the upper substrate 5, and the plurality of first electrode portions 51 are composed only of an electrode film covering the surface of the recess 53. In this case, for example, the second electrode portion 52 may be the same as the first electrode portion 51 and may be composed only of an electrode film covering the surface of the upper substrate 5. In addition, as long as the second electrode portion 52 is electrically independent of the plurality of first electrode portions 51 and is electrically connected to the portion of the recess 53 connected to the oscillator 2, a voltage can be applied to the oscillator 2. For example, the sensor element may also form a through electrode (not shown) extending in the thickness direction of the mounting substrate 3 at the portion of the recess 53 where the oscillator 2 is connected, and may be composed only of an electrode film connected to the through electrode. In addition, the sensor element may be such that when the mounting surface of the mounting portion 22 of the oscillator 2 is a structure protruding from the edge 23, the mounting substrate 3 does not have the recess 53, and the first electrode portion 51 and the second electrode portion 52 are composed only of an electrode film covering the surface of the upper substrate 5. In this way, the structures of the first electrode portion 51 and the second electrode portion 52 in the sensor element can be appropriately changed, and other known structures may also be used. In addition, in Figure 15 order to easily understand the structures of the electrode portions 51 and 52, a part of the oscillator 2 is omitted and a cross section is shown.

[0154] In addition, regarding the sensor element, a structure in which the oscillator 2 has a substantially hemispherical shape or a substantially circular plate shape and the plurality of first electrode portions 51 are arranged so as to surround the oscillator 2 has been described as a representative example, but it is not limited to these forms. For example, as long as the gyro sensor 1 is in a form in which the sensor element can be regarded as Figure 5 the vibrating body of the two-degree-of-freedom system shown, the control unit 10 can always perform modal matching control. Therefore, the forms, arrangements, etc. of the oscillator 2 and the electrode portions 51 and 52 may also be other known forms, arrangements, etc.

[0155] The control unit 10 and its method described in the present disclosure may also be implemented by a dedicated computer provided by a processor and a memory configured to execute one or more functions embodied by a computer program. Alternatively, the control unit 10 and its method described in the present disclosure may also be implemented by a dedicated computer provided by a processor constituted by one or more dedicated hardware logic circuits. Alternatively, the control unit 10 and its method described in the present disclosure may also be implemented by one or more dedicated computers provided by a combination of a processor configured to execute one or more functions and a memory and a processor constituted by one or more hardware logic circuits. In addition, the computer program may also be stored as instructions executable by a computer in a computer-readable non-transitory tangible storage medium.

[0156] In addition, in each of the above-described embodiments, with respect to the elements constituting the embodiments, except for cases where it is specifically specified as essential and cases where it is clearly considered essential in principle, etc., it is not necessarily essential, of course. Further, in the above-described embodiments, when referring to numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiments, except for cases where it is specifically specified as essential and cases where it is clearly limited to a specific number in principle, etc., it is not limited to that specific number. Additionally, in each of the above-described embodiments, when referring to the shape, positional relationship, etc. of the constituent elements, etc., except for cases where it is specifically specified and cases where it is limited to a specific shape, positional relationship, etc. in principle, etc., it is not limited to that shape, positional relationship, etc.

Claims

1. A gyro sensor, characterized in that: have: A vibrator having a first vibration mode and a second vibration mode having different resonant frequencies; A mounting substrate having a plurality of electrodes facing the vibrator; a first PLL circuit that controls the frequency of a drive signal for causing the vibrator to vibrate in the first vibration mode; a second PLL circuit that controls the frequency of a drive signal for causing the vibrator to vibrate in the second vibration mode; a first demodulation unit, defining a radial direction with an imaginary straight line passing through the center of an area surrounded by the plurality of electrodes and along the thickness direction of the mounting substrate as an axis, defining two directions along the radial direction of a driving electrode used for driving the first vibration mode and the second vibration mode among the plurality of electrodes as electrode axes, defining two directions along the radial direction along the vibration directions of the first vibration mode and the second vibration mode as vibration axes, the first demodulation unit calculating a first demodulation output based on a first detection signal from the electrode detecting the vibration of the first vibration mode among the plurality of electrodes and a first drive signal of a frequency of resonance driving in the first vibration mode outputted from the first PLL circuit, and calculating a second demodulation output based on a second detection signal from the electrode detecting the vibration of the second vibration mode among the plurality of electrodes and a second drive signal of a frequency of resonance driving in the second vibration mode outputted from the second PLL circuit; a second demodulation unit that calculates a third demodulation output based on the first detection signal and the second drive signal, and calculates a fourth demodulation output based on the second detection signal and the first drive signal; a first demodulated output calculation unit for calculating the amplitude and phase of the first vibration mode based on the first demodulated output and the third demodulated output; a second demodulated output calculation unit for calculating the amplitude and phase of the second vibration mode based on the second demodulated output and the fourth demodulated output; as well as A control circuit outputs a control signal for aligning the vibration axis with the electrode axis based on an input signal regarding the amplitude and the phase from the first demodulation output calculation unit or the second demodulation output calculation unit.

2. The gyro sensor according to claim 1, characterized in that: The first demodulated output operation unit includes: a high-pass filter that cuts off a part of the first demodulated output and the third demodulated output; and an operation unit that performs a square sum operation by adding the squares of the first demodulated output and the third demodulated output after passing through the high-pass filter to calculate the amplitude of the first vibration mode. and a phase comparison unit that calculates the phase of the first vibration mode based on the first demodulated output and the third demodulated output after passing through the high-pass filter, The second demodulated output operation unit includes: a high-pass filter that cuts off a part of the second demodulated output and the fourth demodulated output; a calculation unit that performs a square sum operation on the second demodulated output and the fourth demodulated output after passing through the high-pass filter and then adds them together to calculate the amplitude of the second vibration mode; and a phase comparison unit that calculates the phase of the second vibration mode based on the second demodulated output and the fourth demodulated output after passing through the high-pass filter.

3. The gyro sensor according to claim 1, characterized in that: The gyro sensor further includes an oscillation circuit that outputs a frequency signal of a difference between a resonant frequency of the first vibration mode and a resonant frequency of the second vibration mode based on the first drive signal and the second drive signal. The first demodulation output calculation unit includes a third demodulation unit, and the third demodulation unit performs demodulation processing using the frequency signal from the oscillation circuit to calculate the amplitude and phase of the first vibration mode. The second demodulated output calculation unit includes a third demodulation unit that performs demodulation processing using the frequency signal from the oscillation circuit to calculate the amplitude and phase of the second vibration mode.

4. The gyro sensor according to claim 2, characterized in that: The gyro sensor further includes a PI circuit that outputs a control signal for making a difference between a resonant frequency of the first vibration mode and a resonant frequency of the second vibration mode zero based on the input signal from the first demodulation output operation unit or the second demodulation output operation unit.

Images