Angular velocity detection circuit

Abstract

This invention provides an angular velocity detection circuit that can achieve a high cutoff frequency. [Solution] The angular velocity detection circuit 20 comprises a first vibration generation unit 21, a second vibration generation unit 22, and a control unit 40. The first vibration generation unit 21 causes the first vibrator 111 and the second vibrator 112 to vibrate in the X direction, with a frequency of the first resonant frequency ω1 and opposite phases. The second vibration generation unit 22 causes the first vibrator 111 and the second vibrator 112 to vibrate in the Y direction, with a frequency of the first resonant frequency ω1 and the same phases. The control unit 40 controls the second resonant frequency ω2 based on signals corresponding to the vibration of the first vibrator 111 and the vibration of the second vibrator 112 when the first vibrator 111 and the second vibrator 112 are vibrating in the X and Y directions, respectively, by the first vibration generation unit 21 and the second vibration generation unit 22.

Description

Technical Field

[0001] The present disclosure relates to an angular velocity detection circuit.

Background Art

[0002] Conventionally, as described in Patent Document 1, a rate sensor that detects an angular velocity by matching a first oscillator to a second oscillator is known. In this rate sensor, two signals that are frequency-shifted symmetrically with respect to the vibration of the second oscillator are generated. Further, the response characteristics of the first oscillator to the generated signals are obtained, and a differential signal is formed. Furthermore, the frequency of the first oscillator is adjusted for matching depending on the differential signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the rate sensor described in Patent Document 1, if the amount of frequency shift with respect to f0, which is the resonance frequency of the vibration of the second oscillator, is α, then α does not exceed f0, so the relationship α < f0 holds. Further, the difference signal is a signal in which a vibration with a frequency changing at α and a vibration with a frequency changing at f0 are superimposed. Furthermore, this difference signal is input to the first oscillator, and a signal with frequency alignment adjusted is output from the first oscillator. Also, the output signal of the first oscillator contains angular velocity information. Therefore, in order to detect the angular velocity, it is necessary to separate, from the output signal of the first oscillator, the information on the frequency alignment adjustment by the difference signal and the angular velocity. Thus, in order to detect the angular velocity, it is necessary to remove high-frequency components with a frequency of fs or higher from the output signal of the first oscillator, thereby removing the component with a frequency of α and the component with a frequency of f0. Therefore, it is necessary to set a cut-off frequency fs for which the relationship fs < α < f0 holds.

[0005] Here, in order to increase the responsiveness of control using the angular velocity, the cut-off frequency fs may be increased. In contrast, in the rate sensor described in Patent Document 1, since there is a relationship fs < α < f0, the maximum that can be achieved is to bring the cut-off frequency fs closer to α, and it cannot be brought closer to f0. Therefore, in the rate sensor described in Patent Document 1, the cut-off frequency fs cannot be increased.

[0006] The present disclosure aims to provide an angular velocity detection circuit capable of increasing the cut-off frequency.

Means for Solving the Problems

[0007] The invention described in claim 1 is an angular velocity detection circuit used in a sensor element (10) comprising a first vibrator (111) and a second vibrator (112) that vibrate in a first direction (X) and a second direction (Y) intersecting the first direction, and having a first resonant frequency (ω1) which is the resonant frequency of vibration in the first direction and a second resonant frequency (ω2) which is the resonant frequency of vibration in the second direction, comprising: a first vibration generating unit (21) that vibrates the first vibrator and the second vibrator in the first direction; a second vibration generating unit (22) that vibrates the first vibrator and the second vibrator in the second direction; and a second resonant frequency The first vibration generating unit comprises a control unit (40) for controlling the wavenumber and a calculation unit (50) for calculating the angular velocity when the sensor element rotates around an axis extending in a third direction (Z) that intersects the first and second directions. The first vibration generating unit outputs to the sensor element a signal that causes the first oscillator to vibrate in the first direction with a frequency of the first resonant frequency, and a signal that causes the second oscillator to vibrate in the first direction with a frequency of the first resonant frequency and a phase opposite to the phase of the vibration of the first oscillator in the first direction, thereby vibrating the first oscillator and generating the axis extending in the third direction. As the sensor element rotates around its center, a Coriolis force acting in a second direction is generated, causing the first oscillator to vibrate in a second direction with a frequency of the first resonant frequency, thereby vibrating the second oscillator. As the sensor element rotates around an axis extending in a third direction, a Coriolis force acting in a second direction is generated, causing the second oscillator to vibrate in a second direction with a frequency of the first resonant frequency and a phase opposite to the phase of the vibration of the first oscillator in the second direction due to the Coriolis force, and the second vibration generating unit vibrates in a second direction. The control unit outputs to the sensor element a signal that causes the first oscillator to vibrate at the first resonant frequency, and a signal that causes the second oscillator to vibrate in the second direction, with a phase corresponding to the phase of the vibration of the first oscillator in the second direction by the second vibration generating unit. The control unit controls the second resonant frequency based on the signal corresponding to the vibration of the first oscillator and the signal corresponding to the vibration of the second oscillator when the first and second oscillators are vibrating in the first and second directions by the first and second vibration generating units. The calculation unit uses the signal output from the first vibration generating unit to the sensor element,This angular velocity detection circuit calculates angular velocity based on a signal obtained by subtracting the signal corresponding to the vibration of the second oscillator (when the first and second oscillators are vibrating in the first and second directions, respectively) from the signal corresponding to the vibration of the first oscillator (when the first and second oscillators are vibrating in the first and second directions, respectively) by the first and second vibration generating units, and the cutoff frequency (fs).

[0008] This allows the second resonant frequency to be set to the first resonant frequency without using a signal whose frequency has been shifted relative to the resonant frequency. Therefore, the cutoff frequency can be brought closer to both the first and second resonant frequencies. Consequently, the cutoff frequency can be increased.

[0009] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0010] [Figure 1] A diagram showing the configuration of a sensor element using the angular velocity detection circuit of the first embodiment. [Figure 2] Diagram of the angular velocity detection circuit. [Figure 3] Configuration diagram of the control unit of the angular velocity detection circuit. [Figure 4] This diagram shows the sensor elements when the first and second oscillators of the angular velocity detection circuit are vibrating in the X direction due to the first vibration generation unit. [Figure 5] This diagram shows the sensor elements when the first and second oscillators are vibrating in the X direction due to the second vibration generation unit of the angular velocity detection circuit. [Figure 6] This diagram shows the sensor element when it rotates around an axis extending in the Z direction, while the first and second oscillators are vibrating in the X direction. [Figure 7] A diagram showing the relationship between frequency and amplitude when the first and second oscillators are vibrating. [Figure 8] Configuration diagram of the control unit of the angular velocity detection circuit in the second embodiment. [Figure 9] Configuration diagram of the angular velocity detection circuit of the third embodiment. [Figure 10] Configuration diagram of the first control unit of the angular velocity detection circuit. [Figure 11] Configuration diagram of the second control unit of the angular velocity detection circuit. [Figure 12] Configuration diagram of the first control unit of the angular velocity detection circuit in the fourth embodiment. [Figure 13] Configuration diagram of the second control unit of the angular velocity detection circuit. [Figure 14] Configuration diagram of the sensor element used in the angular velocity detection circuit of the fifth embodiment. [Figure 15] Configuration diagram of the angular velocity detection circuit. [Figure 16] Configuration diagram of the angular velocity detection circuit of the sixth embodiment.

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals, and the description thereof will be omitted.

[0012] (First Embodiment) The angular velocity detection circuit of the present embodiment is used for the sensor element 10 as shown in FIG. 1, and can increase the cut-off frequency fs. First, the sensor element 10 will be described.

[0013] Here, one direction is defined as the X direction. The direction orthogonal to the X direction is defined as the Y direction. The direction orthogonal to the X direction and the Y direction is defined as the Z direction. Note that the X direction corresponds to the first direction. The Y direction corresponds to the second direction intersecting the first direction. The Z direction corresponds to the third direction intersecting the first direction and the second direction.

[0014] The sensor element 10 includes a first housing portion 101, a first vibrator 111, a first Y-direction elastic portion 121, a second Y-direction elastic portion 122, a first electrode 131, and a second electrode 132. Further, the sensor element 10 includes a second housing portion 102, a second vibrator 112, a third Y-direction elastic portion 123, a fourth Y-direction elastic portion 124, a third electrode 133, and a fourth electrode 134. Furthermore, the sensor element 10 includes a first X-direction elastic portion 141, a first fixing portion 151, a second X-direction elastic portion 142, a second fixing portion 152, and a third X-direction elastic portion 143.

[0015] The first housing portion 101 houses the first vibrator 111, the first Y-direction elastic portion 121, the second Y-direction elastic portion 122, the first electrode 131, and the second electrode 132, which will be described later.

[0016] The first vibrator 111 vibrates in the X direction and the Y direction by an angular velocity detection circuit, which will be described later. The first vibrator 111 has a first resonance frequency ω1 and a second resonance frequency ω2. The first resonance frequency ω1 is the resonance frequency of vibration in the X direction. The second resonance frequency ω2 is the resonance frequency of vibration in the Y direction.

[0017] One end of the first Y-direction elastic portion 121 is connected to the first vibrator 111 in the Y direction. The other end of the first Y-direction elastic portion 121 is connected to the first housing portion 101 in the Y direction. Therefore, the first Y-direction elastic portion 121 vibrates in the Y direction together with the first vibrator 111.

[0018] One end of the second Y-direction elastic portion 122 is connected to the side of the first vibrator 111 opposite to the first Y-direction elastic portion 121 in the Y direction. The other end of the second Y-direction elastic portion 122 is connected to the side of the first housing portion 101 opposite to the first Y-direction elastic portion 121 in the Y direction. Thus, the second Y-direction elastic portion 122 vibrates in the Y direction together with the first vibrator 111.

[0019] The first electrode 131 is positioned in the Y direction opposite to the portion of the first resonator 111 that is connected to the first elastic portion 121 in the Y direction. Furthermore, when the first resonator 111 vibrates in the Y direction, the distance between the first electrode 131 and the first resonator 111 changes, causing the first capacitance Cs1 to change. The first electrode 131 also outputs a signal corresponding to the change in the first capacitance Cs1. The first capacitance Cs1 is the capacitance between the first electrode 131 and the first resonator 111.

[0020] The second electrode 132 faces the portion of the first resonator 111 that is connected to the second elastic portion 122 in the Y direction, in the Y direction. Therefore, the second electrode 132 faces the portion of the first resonator 111 opposite to the first electrode 131, in the Y direction. Furthermore, when the first resonator 111 vibrates in the Y direction, the distance between the second electrode 132 and the first resonator 111 changes, causing a change in the second capacitance Cs2. The second electrode 132 also outputs a signal corresponding to the change in the second capacitance Cs2. The second capacitance Cs2 is the capacitance between the second electrode 132 and the first resonator 111.

[0021] Furthermore, as the distance between the first electrode 131 and the first oscillator 111 decreases, the first capacitance Cs1 increases. Also, at this time, the distance between the second electrode 132 and the first oscillator 111 increases, causing the second capacitance Cs2 to decrease. Therefore, when the first oscillator 111 vibrates in the Y direction, the sign of the change in the first capacitance Cs1 is opposite to the sign of the change in the second capacitance Cs2.

[0022] The second housing section 102 houses the second oscillator 112, the third elastic section 123 in the Y direction, the fourth elastic section 124 in the Y direction, the third electrode 133, and the fourth electrode 134, which will be described later.

[0023] The second oscillator 112 vibrates in the X and Y directions by the angular velocity detection circuit described later. Furthermore, the second oscillator 112 has a first resonant frequency ω1 and a second resonant frequency ω2. The first resonant frequencies ω1 and ω2 of the second oscillator 112 are the same as the first resonant frequencies ω1 and ω2 of the first oscillator 111. Note that "same" includes the manufacturing tolerance range.

[0024] The third elastic section 123 in the Y direction passes through the first elastic section 121 in the Y direction and is positioned on a plane parallel to the X direction. Furthermore, one end of the third elastic section 123 in the Y direction is connected to the second oscillator 112 in the Y direction. The other end of the third elastic section 123 in the Y direction is connected to the second housing section 102 in the Y direction. Therefore, the third elastic section 123 in the Y direction vibrates together with the second oscillator 112 in the Y direction.

[0025] The fourth elastic section 124 in the Y direction passes through the second elastic section 122 in the Y direction and is positioned on a plane parallel to the X direction. One end of the fourth elastic section 124 in the Y direction is connected in the Y direction to the side of the second oscillator 112 opposite to the third elastic section 123 in the Y direction. The other end of the fourth elastic section 124 in the Y direction is connected in the Y direction to the side of the second housing section 102 opposite to the third elastic section 123 in the Y direction. Therefore, the fourth elastic section 124 in the Y direction vibrates in the Y direction together with the second oscillator 112.

[0026] The third electrode 133 is positioned in the Y direction opposite the portion of the second resonator 112 that is connected to the third elastic portion 123 in the Y direction. Furthermore, when the second resonator 112 vibrates in the Y direction, the distance between the third electrode 133 and the second resonator 112 changes, causing the third capacitance Cs3 to change. The third electrode 133 also outputs a signal corresponding to the change in the third capacitance Cs3. The third capacitance Cs3 is the capacitance between the third electrode 133 and the second resonator 112.

[0027] The fourth electrode 134 faces the portion of the second resonator 112 that is connected to the fourth elastic portion 124 in the Y direction, in the Y direction. Therefore, the fourth electrode 134 faces the portion of the second resonator 112 opposite to the third electrode 133, in the Y direction. Furthermore, when the second resonator 112 vibrates in the Y direction, the distance between the fourth electrode 134 and the second resonator 112 changes, causing the fourth capacitance Cs4 to change. The fourth electrode 134 also outputs a signal corresponding to the change in the fourth capacitance Cs4. The fourth capacitance Cs4 is the capacitance between the fourth electrode 134 and the second resonator 112.

[0028] Furthermore, as the distance between the third electrode 133 and the second oscillator 112 decreases, the third capacitance Cs3 increases. Also, at this time, the distance between the fourth electrode 134 and the second oscillator 112 increases, causing the fourth capacitance Cs4 to decrease. Therefore, when the second oscillator 112 vibrates in the Y direction, the sign of the change in the third capacitance Cs3 is opposite to the sign of the change in the fourth capacitance Cs4.

[0029] One end of the first elastic portion 141 in the X direction is connected to the first housing portion 101 in the X direction. The other end of the first elastic portion 141 in the X direction is connected to the first fixing portion 151 in the X direction. The first fixing portion 151 is fixed to a housing or the like (not shown).

[0030] One end of the second elastic portion 142 in the X direction is connected to the second housing portion 102 in the X direction. The other end of the second elastic portion 142 in the X direction is connected to the second fixing portion 152 in the X direction. The second fixing portion 152 is fixed to a housing or the like (not shown).

[0031] The third elastic portion 143 in the X direction is positioned between the first housing portion 101 and the second housing portion 102 in the X direction. One end of the third elastic portion 143 in the X direction is connected in the X direction to the side of the first housing portion 101 opposite to the first elastic portion 141 in the X direction. The other end of the third elastic portion 143 in the X direction is connected in the X direction to the side of the second housing portion 102 opposite to the second elastic portion 142 in the X direction.

[0032] Therefore, the first elastic portion 141 in the X direction, the second elastic portion 142 in the X direction, and the third elastic portion 143 in the X direction vibrate in the X direction together with the first resonator 111 housed in the first housing portion 101 and the second resonator 112 housed in the second housing portion 102.

[0033] As described above, the sensor element 10 is configured as described. Next, the configuration of the angular velocity detection circuit used in the sensor element 10 will be explained.

[0034] As shown in Figure 2, the angular velocity detection circuit 20 includes a first vibration generation unit 21, a second vibration generation unit 22, a first detection unit 31, a second detection unit 32, an addition unit 35, a control unit 40, a subtraction unit 45, and an angular velocity calculation unit 50.

[0035] The first vibration generation unit 21 includes a PLL, a VCO, and a gain controller, etc. PLL stands for Phase Locked Loop, and VCO stands for Voltage Controlled Oscillator.

[0036] As a result, the first vibration generating unit 21 outputs signals to the first vibrator 111 and the second vibrator 112 of the sensor element 10 that cause the first vibrator 111 and the second vibrator 112 to vibrate in the X direction. Furthermore, the first vibration generating unit 21 acquires signals from the sensor element 10 corresponding to the vibrations of the first vibrator 111 and the second vibrator 112 in the X direction. In addition, the first vibration generating unit 21 adjusts the vibration frequencies of the first vibrator 111 and the second vibrator 112 in the X direction to be the first resonant frequency ω1, based on the signals output to the first vibrator 111 and the second vibrator 112 and the signals acquired from the sensor element 10. Furthermore, the first vibration generating unit 21 adjusts the vibration phases of the first vibrator 111 and the second vibrator 112 in the X direction so that the phase of the vibration of the second vibrator 112 in the X direction is inversely phase to the phase of the vibration of the first vibrator 111 in the X direction. Furthermore, the first vibration generating unit 21 adjusts the amplitude of vibration of the first oscillator 111 and the second oscillator 112 in the X direction.

[0037] Therefore, the first vibration generating unit 21 outputs a signal to the sensor element 10 that causes the first vibrator 111 to vibrate in the X direction with a frequency of the first resonant frequency ω1. Furthermore, the first vibration generating unit 21 outputs a signal to the sensor element 10 that causes the second vibrator 112 to vibrate in the X direction with a frequency of the first resonant frequency ω1 and a phase opposite to the phase of the vibration of the first vibrator 111 in the X direction.

[0038] The second vibration generating unit 22 has input / output circuits, etc. The second vibration generating unit 22 receives signals from the first vibration generating unit 21 that were acquired from the sensor element 10, i.e., signals corresponding to the vibrations of the first vibrator 111 and the second vibrator 112 in the X direction. The second vibration generating unit 22 also outputs signals corresponding to the vibrations of the first vibrator 111 and the second vibrator 112 in the X direction, acquired from the first vibration generating unit 21, to the sensor element 10. As a result, the second vibration generating unit 22 causes the first vibrator 111 and the second vibrator 112 to vibrate in the Y direction.

[0039] Here, the phase of the signal output from the first vibration generation unit 21 to the sensor element 10 and the phase of the signal corresponding to the vibration of the first vibrator 111 and the second vibrator 112 in the X direction are 90° apart.

[0040] Therefore, the second vibration generating unit 22 outputs a signal to the sensor element 10 that causes the first vibrator 111 to vibrate in the Y direction, with a frequency of the first resonant frequency ω1, and a phase that is 90° different from the phase of the vibration of the first vibrator 111 in the X direction. Furthermore, the second vibration generating unit 22 outputs a signal to the sensor element 10 that causes the second vibrator 112 to vibrate in the Y direction, with a frequency of the first resonant frequency ω1, and a phase that is the same as the phase of the vibration of the first vibrator 111 in the Y direction caused by the second vibration generating unit 22.

[0041] The first detection unit 31 includes a fully differential amplifier and is connected to the first electrode 131 and the second electrode 132. As a result, the first detection unit 31 acquires a signal corresponding to the change in the first capacitance Cs1 from the first electrode 131 as a signal corresponding to the vibration of the first resonator 111 when the first resonator 111 and the second resonator 112 are vibrating in the X and Y directions. The first detection unit 31 also acquires a signal corresponding to the change in the second capacitance Cs2 from the second electrode 132 as a signal corresponding to the vibration of the first resonator 111 when the first resonator 111 and the second resonator 112 are vibrating in the X and Y directions. Furthermore, based on these acquired signals from the first electrode 131 and the second electrode 132, the first detection unit 31 detects the displacement of the first resonator 111 in the Y direction. Furthermore, the first detection unit 31 outputs a signal corresponding to the detected displacement of the first oscillator 111 in the Y direction to the addition unit 35 and subtraction unit 45, which will be described later.

[0042] The second detection unit 32 has a fully differential amplifier and is connected to the third electrode 133 and the fourth electrode 134. As a result, the second detection unit 32 acquires a signal corresponding to the change in the third capacitance Cs3 from the third electrode 133 as a signal corresponding to the vibration of the second resonator 112 when the first resonator 111 and the second resonator 112 are vibrating in the X and Y directions. Furthermore, the second detection unit 32 acquires a signal corresponding to the change in the fourth capacitance Cs4 from the fourth electrode 134 as a signal corresponding to the vibration of the second resonator 112 when the first resonator 111 and the second resonator 112 are vibrating in the X and Y directions. The second detection unit 32 also detects the displacement of the second resonator 112 in the Y direction based on these acquired signals from the third electrode 133 and the fourth electrode 134. Furthermore, the second detection unit 32 outputs a signal corresponding to the detected displacement of the second oscillator 112 in the Y direction to the addition unit 35 and subtraction unit 45, which will be described later.

[0043] The summing unit 35 acquires a signal corresponding to the displacement of the first oscillator 111 in the Y direction from the first detection unit 31. The summing unit 35 also acquires a signal corresponding to the displacement of the second oscillator 112 in the Y direction from the second detection unit 32. Furthermore, the summing unit 35 includes an operational amplifier, an AD converter, and a microcontroller. As a result, the summing unit 35 adds the acquired signals corresponding to the displacement of the first oscillator 111 in the Y direction and the signals corresponding to the displacement of the second oscillator 112 in the Y direction. The summing unit 35 then outputs this added signal to the control unit 40, which will be described later.

[0044] The control unit 40 obtains a signal from the first vibration generation unit 21 that causes the first vibrator 111 and the second vibrator 112 to vibrate in the X direction, with a frequency of the first resonant frequency ω1 and opposite phases. Furthermore, the control unit 40 obtains a signal from the first vibration generation unit 21 corresponding to the vibrations of the first vibrator 111 and the second vibrator 112 in the X direction. In addition, the control unit 40 obtains a signal from the summing unit 35 which is the sum of the signal corresponding to the displacement of the first vibrator 111 in the Y direction and the signal corresponding to the displacement of the second vibrator 112 in the Y direction. Furthermore, the control unit 40 controls the second resonant frequency ω2 based on these obtained signals.

[0045] For example, the control unit 40 has a phase comparison unit 400 and a controller 410, as shown in Figure 3.

[0046] The phase comparison unit 400 acquires signals from the first vibration generation unit 21 that cause the first oscillator 111 and the second oscillator 112 to vibrate in the X direction, with a frequency of the first resonant frequency ω1 and opposite phases. The phase comparison unit 400 also acquires a signal from the summing unit 35 that is the sum of the signal corresponding to the displacement of the first oscillator 111 in the Y direction and the signal corresponding to the displacement of the second oscillator 112 in the Y direction. Furthermore, the phase comparison unit 400 includes a PLL, etc. Based on this, the phase comparison unit 400 calculates the phase difference Δθ of the acquired signals. The phase comparison unit 400 also outputs a signal corresponding to this calculated phase difference Δθ to the controller 410, which will be described later.

[0047] Here, let's assume that the second resonant frequency ω2 coincides with the first resonant frequency ω1. In this case, the phase of the first signal and the phase of the second signal are the same. The first signal is a signal corresponding to the displacement of the first oscillator 111 in the Y direction and a signal corresponding to the displacement of the second oscillator 112 in the Y direction. The second signal is a vibration in the X direction, with a frequency of the first resonant frequency ω1 and opposite phases, which causes the first oscillator 111 and the second oscillator 112 to vibrate. Since the phase of the first signal and the phase of the second signal are the same, the phase difference Δθ becomes zero.

[0048] Therefore, the controller 410 obtains a signal corresponding to the phase difference Δθ from the phase comparison unit 400. Furthermore, the controller 410 calculates a signal that makes the phase difference Δθ zero by using this obtained signal corresponding to the phase difference Δθ and PI control, etc. The controller 410 also outputs this calculated signal that makes the phase difference Δθ zero to the sensor element 10. As a result, the effective spring constant of the sensor element 10 in the Y direction changes. Consequently, the second resonant frequency ω2 changes. Therefore, the controller 410 brings the second resonant frequency ω2 closer to the first resonant frequency ω1 by bringing the phase difference Δθ closer to zero. The effective spring constant is the sum of the first sum S1, the second sum S2, and the third sum S3. The first sum S1 is the sum of the spring constants of the first elastic part 121 in the Y direction, the second elastic part 122 in the Y direction, the third elastic part 123 in the Y direction, and the fourth elastic part 124 in the Y direction. The second sum S2 is the sum of the electrical spring constant between the first electrode 131 and the first resonator 111 and the electrical spring constant between the second electrode 132 and the first resonator 111. The third sum S3 is the sum of the electrical spring constant between the third electrode 133 and the second resonator 112 and the electrical spring constant between the fourth electrode 134 and the second resonator 112.

[0049] Returning to Figure 2, the subtraction unit 45 acquires a signal corresponding to the displacement of the first oscillator 111 in the Y direction from the first detection unit 31. Furthermore, the subtraction unit 45 acquires a signal corresponding to the displacement of the second oscillator 112 in the Y direction from the second detection unit 32. The subtraction unit 45 also includes an operational amplifier, an AD converter, and a microcontroller. As a result, the subtraction unit 45 subtracts the signal corresponding to the displacement of the second oscillator 112 in the Y direction from the signal corresponding to the displacement of the first oscillator 111 in the Y direction that was acquired above. Furthermore, the subtraction unit 45 outputs this subtracted signal to the angular velocity calculation unit 50, which will be described later.

[0050] The angular velocity calculation unit 50 corresponds to the calculation unit and acquires a signal from the first vibration generation unit 21 that causes the first oscillator 111 and the second oscillator 112 to vibrate in the X direction, with a frequency of the first resonant frequency ω1 and opposite phases. The angular velocity calculation unit 50 also acquires a signal from the subtraction unit 45 obtained by subtracting a signal corresponding to the displacement of the second oscillator 112 in the Y direction from a signal corresponding to the displacement of the first oscillator 111 in the Y direction. Furthermore, the angular velocity calculation unit 50 has a synchronous detection circuit, etc. As a result, the angular velocity calculation unit 50 demodulates the signal acquired from the subtraction unit 45 to correspond to the frequency and phase of the signal acquired from the first vibration generation unit 21. The angular velocity calculation unit 50 also has a low-pass filter, etc. As a result, the angular velocity calculation unit 50 removes high-frequency components above the cutoff frequency fs contained in the demodulated signal. Furthermore, the angular velocity calculation unit 50 has an AD converter and a microcontroller, etc. As a result, the angular velocity calculation unit 50 calculates the angular velocity of the sensor element 10 from the signal from which high-frequency components above the cutoff frequency fs have been removed. The angular velocity of the sensor element 10 is the angular velocity when the sensor element 10 rotates around an axis extending in the Z direction.

[0051] As described above, the angular velocity detection circuit 20 of the first embodiment is configured as described. Next, the angular velocity detection circuit 20 will be described.

[0052] As shown in Figure 4, the first vibration generating unit 21 causes the first oscillator 111 to vibrate in the X direction with a frequency of the first resonant frequency ω1. At the same time, the first vibration generating unit 21 also causes the second oscillator 112 to vibrate in the X direction with a frequency of the first resonant frequency ω1, and with a phase opposite to that of the vibration of the first oscillator 111 in the X direction.

[0053] Here, the signal output from the first vibration generation unit 21 to the sensor element 10 is a sine wave, and with t as time, the signal output from the first vibration generation unit 21 to the sensor element 10 is defined as sin(ω1×t), as shown in Figure 2. sin(ω1×t) is a vibration in the X direction, with a frequency of the first resonant frequency ω1, and corresponds to a signal that causes the first oscillator 111 and the second oscillator 112 to vibrate with opposite phases.

[0054] At this time, the phase of the signal output from the first vibration generation unit 21 to the sensor element 10 and the phase of the signal corresponding to the vibration of the first vibrator 111 and the second vibrator 112 in the X direction are 90° apart. Therefore, the signal corresponding to the vibration of the first vibrator 111 and the second vibrator 112 in the X direction, which the first vibration generation unit 21 acquires from the sensor element 10, is cos(ω1×t).

[0055] Furthermore, the first vibration generation unit 21 outputs sin(ω1×t) to the control unit 40 and the angular velocity calculation unit 50. The first vibration generation unit 21 also outputs cos(ω1×t) to the second vibration generation unit 22 and the control unit 40.

[0056] Furthermore, as shown in Figure 5, the second vibration generating unit 22 causes the first oscillator 111 to vibrate in the Y direction, corresponding to cos(ω1×t). At the same time, the second vibration generating unit 22 causes the second oscillator 112 to vibrate in the Y direction, with a phase that is the same as the phase of the vibration of the first oscillator 111 in the Y direction caused by the second vibration generating unit 22.

[0057] Returning to Figure 2, the first detection unit 31 acquires a signal corresponding to the change in the first capacitance Cs1 from the first electrode 131 as a signal corresponding to the vibration of the first resonator 111 when the first resonator 111 and the second resonator 112 are vibrating in the X and Y directions. Furthermore, the first detection unit 31 acquires a signal corresponding to the change in the second capacitance Cs2 from the second electrode 132 as a signal corresponding to the vibration of the first resonator 111 when the first resonator 111 and the second resonator 112 are vibrating in the X and Y directions. In addition, the first detection unit 31 detects the displacement of the first resonator 111 in the Y direction based on these acquired signals from the first electrode 131 and the second electrode 132. Furthermore, the first detection unit 31 outputs a signal corresponding to this detected displacement of the first resonator 111 in the Y direction to the adder 35 and the subtractor 45.

[0058] Furthermore, the second detection unit 32 acquires a signal corresponding to the change in the third capacitance Cs3 from the third electrode 133 as a signal corresponding to the vibration of the second oscillator 112 when the first oscillator 111 and the second oscillator 112 are vibrating in the X and Y directions. In addition, the second detection unit 32 acquires a signal corresponding to the change in the fourth capacitance Cs4 from the fourth electrode 134 as a signal corresponding to the vibration of the second oscillator 112 when the first oscillator 111 and the second oscillator 112 are vibrating in the X and Y directions. Furthermore, the second detection unit 32 detects the displacement of the second oscillator 112 in the Y direction based on these acquired signals from the third electrode 133 and the fourth electrode 134. Furthermore, the second detection unit 32 outputs a signal corresponding to the detected displacement of the second oscillator 112 in the Y direction to the adder 35 and the subtractor 45.

[0059] Here, we assume that the sensor element 10 rotates around an axis extending in the Z direction when the first oscillator 111 and the second oscillator 112 are vibrating in the X direction, with a frequency of the first resonant frequency ω1, and with opposite phases to each other.

[0060] At this time, a Coriolis force acting in the Y direction is generated on the first oscillator 111 and the second oscillator 112. Due to this Coriolis force, the first oscillator 111 generates an oscillation in the Y direction with a frequency of the first resonant frequency ω1. Also, as shown in Figure 6, the second oscillator 112 generates an oscillation in the Y direction with a frequency of the first resonant frequency ω1, and a phase opposite to the phase of the oscillation of the first oscillator 111 in the Y direction caused by the Coriolis force.

[0061] Furthermore, at this time, the signal corresponding to the displacement of the first oscillator 111 in the Y direction includes the vibration component of the first oscillator 111 caused by the second vibration generating unit 22 and the vibration component of the first oscillator 111 caused by the Coriolis force. Similarly, the signal corresponding to the displacement of the second oscillator 112 in the Y direction includes the vibration component of the second oscillator 112 caused by the second vibration generating unit 22 and the vibration component of the second oscillator 112 caused by the Coriolis force. Moreover, as described above, the phase of the vibration of the second oscillator 112 caused by the Coriolis force is inversely phase to the phase of the vibration of the first oscillator 111 caused by the Coriolis force. Therefore, when the signal corresponding to the displacement of the first oscillator 111 in the Y direction and the signal corresponding to the displacement of the second oscillator 112 in the Y direction are added together, the vibration component caused by the Coriolis force is removed, and the vibration component from the second vibration generating unit 22 remains.

[0062] Therefore, returning to Figure 2, the summing unit 35 acquires a signal corresponding to the displacement of the first oscillator 111 in the Y direction from the first detection unit 31. The summing unit 35 also acquires a signal corresponding to the displacement of the second oscillator 112 in the Y direction from the second detection unit 32. Furthermore, the summing unit 35 adds the signal corresponding to the displacement of the first oscillator 111 in the Y direction and the signal corresponding to the displacement of the second oscillator 112 in the Y direction. As a result, the summing unit 35 removes the vibration component due to the Coriolis force and calculates the vibration component due to the second vibration generation unit 22. The summing unit 35 also outputs the added signal to the phase comparison unit 400.

[0063] As shown in Figure 3, the phase comparison unit 400 acquires sin(ω1×t) from the first vibration generation unit 21. Furthermore, the phase comparison unit 400 acquires a signal from the summing unit 35 that is the sum of a signal corresponding to the displacement of the first oscillator 111 in the Y direction and a signal corresponding to the displacement of the second oscillator 112 in the Y direction. The phase comparison unit 400 also calculates the phase difference Δθ of these acquired signals. Furthermore, the phase comparison unit 400 outputs a signal corresponding to this calculated phase difference Δθ to the controller 410. Note that the phase difference Δθ is the difference between the phase of sin(ω1×t) and the phase of the signal that is the sum of the signal corresponding to the displacement of the first oscillator 111 in the Y direction and the signal corresponding to the displacement of the second oscillator 112 in the Y direction.

[0064] The controller 410 acquires a signal corresponding to the phase difference Δθ from the phase comparison unit 400. The controller 410 also calculates a signal that makes the phase difference Δθ zero by using this acquired signal corresponding to the phase difference Δθ and PI control, etc. Furthermore, the controller 410 outputs this calculated signal that makes the phase difference Δθ zero to the sensor element 10. As a result, the effective spring constant of the sensor element 10 in the Y direction changes. Therefore, the second resonant frequency ω2 changes. Accordingly, the controller 410 brings the second resonant frequency ω2 closer to the first resonant frequency ω1 by bringing the phase difference Δθ closer to zero. When the phase difference Δθ becomes zero, the second resonant frequency ω2 becomes the first resonant frequency ω1.

[0065] When the second resonant frequency ω2 becomes the first resonant frequency ω1, the amplitude of the vibrations of the first oscillator 111 and the second oscillator 112 in the Y direction becomes maximum, as shown in Figure 7. Therefore, the vibration component due to the Coriolis force included in the vibrations of the first oscillator 111 and the second oscillator 112 in the Y direction becomes maximum. Consequently, it becomes easier to calculate the angular velocity from the vibration component due to the Coriolis force. In Figure 7, the amplitude of the vibrations of the first oscillator 111 and the second oscillator 112 in the X direction as a function of frequency is shown as Vx. The amplitude of the vibrations of the first oscillator 111 and the second oscillator 112 in the Y direction as a function of frequency is shown as Vy.

[0066] Furthermore, as described above, the signal corresponding to the displacement of the first oscillator 111 in the Y direction includes the vibration component of the first oscillator 111 caused by the second vibration generating unit 22 and the vibration component of the first oscillator 111 due to the Coriolis force. In addition, the signal corresponding to the displacement of the second oscillator 112 in the Y direction includes the vibration component of the second oscillator 112 caused by the second vibration generating unit 22 and the vibration component of the second oscillator 112 due to the Coriolis force. Moreover, the phase of the vibration of the second oscillator 112 caused by the second vibration generating unit 22 is the same as the phase of the vibration of the first oscillator 111 caused by the second vibration generating unit 22. For this reason, when the signal corresponding to the displacement of the second oscillator 112 in the Y direction is subtracted from the signal corresponding to the displacement of the first oscillator 111 in the Y direction, the vibration component from the second vibration generating unit 22 is removed, and the vibration component due to the Coriolis force remains.

[0067] Therefore, returning to Figure 2, the subtraction unit 45 acquires a signal corresponding to the displacement of the first oscillator 111 in the Y direction from the first detection unit 31. Furthermore, the subtraction unit 45 acquires a signal corresponding to the displacement of the second oscillator 112 in the Y direction from the second detection unit 32. The subtraction unit 45 also subtracts the signal corresponding to the displacement of the second oscillator 112 in the Y direction from these acquired signals corresponding to the displacement of the first oscillator 111 in the Y direction. In this way, the subtraction unit 45 removes the vibration component from the second vibration generation unit 22 and calculates the vibration component due to the Coriolis force. Furthermore, the subtraction unit 45 outputs the subtracted signal to the angular velocity calculation unit 50.

[0068] The angular velocity calculation unit 50 acquires sin(ω1×t) from the first vibration generation unit 21. Further, the angular velocity calculation unit 50 acquires, from the subtraction unit 45, a signal obtained by subtracting a signal corresponding to the displacement of the second vibrator 112 in the Y direction from a signal corresponding to the displacement of the first vibrator 111 in the Y direction. Furthermore, the angular velocity calculation unit 50 performs demodulation corresponding to the frequency and phase of sin(ω1×t) on the signal acquired from the subtraction unit 45. Also, the angular velocity calculation unit 50 removes high-frequency components with a cut-off frequency of fs or higher included in the demodulated signal. Further, the angular velocity calculation unit 50 calculates the angular velocity of the sensor element 10 from the signal from which the high-frequency components with a cut-off frequency of fs or higher have been removed. Therefore, the angular velocity calculation unit 50 calculates the angular velocity of the sensor element 10 based on the signal output from the first vibration generation unit 21 to the sensor element 10, the signal from the subtraction unit 45, and the cut-off frequency fs.

[0069] As described above, the angular velocity detection circuit 20 operates. Next, an explanation will be given of the fact that the angular velocity detection circuit 20 can increase the cut-off frequency fs.

[0070] Here, in the angular rate sensor described in Patent Document 1, since there is a relationship of fs < α < f0, it is maximally possible to bring the cut-off frequency fs close to α, and it is not possible to bring it close to f0, which is the resonance frequency of the vibration of the second oscillator. Therefore, in the angular rate sensor described in Patent Document 1, the cut-off frequency fs cannot be increased. Note that α is the amount of frequency shift with respect to f0, as described above.

[0071] In contrast, the angular velocity detection circuit 20 of the present embodiment includes a first vibration generation unit 21, a second vibration generation unit 22, and a control unit 40.

[0072] The first vibration generating unit 21 outputs a signal to the sensor element 10 that causes the first oscillator 111 to vibrate in the X direction with a frequency of the first resonant frequency ω1. The first vibration generating unit 21 also outputs a signal that causes the second oscillator 112 to vibrate in the X direction with a frequency of the first resonant frequency ω1, and a phase opposite to the phase of the vibration of the first oscillator 111 in the X direction.

[0073] The second vibration generating unit 22 outputs a signal to the sensor element 10 that causes the first oscillator 111 to vibrate in the Y direction with a frequency of the first resonant frequency ω1. Furthermore, the second vibration generating unit 22 outputs a signal to the sensor element 10 that causes the second oscillator 112 to vibrate in the Y direction with a phase that is the same as or corresponding to the phase of the first oscillator 111 in the Y direction.

[0074] Assume that the first vibrator 111 and the second vibrator 112 are vibrating in the X and Y directions due to the first vibration generating unit 21 and the second vibration generating unit 22. The control unit 40 controls the second resonant frequency ω2 based on the signals corresponding to the vibration of the first vibrator 111 and the vibration of the second vibrator 112 at this time.

[0075] This allows the second resonant frequency ω2 to be set to the first resonant frequency ω1 without using a signal with a frequency shift relative to the resonant frequency. Therefore, the cutoff frequency fs can be brought closer to the first resonant frequency ω1 and the second resonant frequency ω2. Consequently, the cutoff frequency fs can be increased. Furthermore, a higher cutoff frequency fs improves the responsiveness of control using angular velocity.

[0076] Furthermore, the angular velocity detection circuit 20 of the first embodiment also provides the following effects.

[0077] [1] The control unit 40 controls the second resonant frequency ω2 based on the phase difference Δθ, which is the difference between the phase of the signal added in the adder 35 and the phase of sin(ω1×t). Specifically, the control unit 40 brings the second resonant frequency ω2 closer to the first resonant frequency ω1 by bringing the phase difference Δθ closer to zero. This makes it easier to control the second resonant frequency ω2. sin(ω1×t) corresponds to the signal output from the first vibration generation unit 21 to the sensor element 10.

[0078] (Second Embodiment) In the second embodiment, the configuration and processing of the control unit 40 differ from those of the first embodiment. Otherwise, it is the same as in the first embodiment.

[0079] Specifically, as shown in Figure 8, the control unit 40 includes a synchronous detection unit 420 instead of a phase comparison unit 400.

[0080] The synchronous detection unit 420 acquires cos(ω1×t) from the first vibration generation unit 21. The synchronous detection unit 420 also acquires a signal from the summing unit 35 that is the sum of a signal corresponding to the displacement of the first oscillator 111 in the Y direction and a signal corresponding to the displacement of the second oscillator 112 in the Y direction. Furthermore, the synchronous detection unit 420 includes a synchronous detection circuit, etc. As a result, the synchronous detection unit 420 demodulates the signal, which is the sum of the signal corresponding to the displacement of the first oscillator 111 in the Y direction and the signal corresponding to the displacement of the second oscillator 112 in the Y direction, with the frequency and phase corresponding to cos(ω1×t). The synchronous detection unit 420 also outputs the demodulated signal Sd to the controller 410. Note that cos(ω1×t) corresponds to the signal acquired by the first vibration generation unit 21 from the sensor element 10, and also corresponds to the signal output from the second vibration generation unit 22 to the sensor element 10. The demodulated signal Sd is a signal obtained by adding a signal corresponding to the displacement of the first oscillator 111 in the Y direction and a signal corresponding to the displacement of the second oscillator 112 in the Y direction, and then demodulating the result to a frequency and phase corresponding to cos(ω1×t).

[0081] Here, when the second resonant frequency ω2 coincides with the first resonant frequency ω1, the signals corresponding to the displacement of the first oscillator 111 in the Y direction and the signals corresponding to the displacement of the second oscillator 112 in the Y direction become signals related to sin(ω1×t). Therefore, the DC component of the demodulated signal Sd becomes zero.

[0082] Therefore, the controller 410 acquires the demodulated signal Sd from the synchronous detection unit 420. Furthermore, the controller 410 calculates a signal that makes the DC component of the demodulated signal Sd zero by using the acquired demodulated signal Sd and PI control, etc. The controller 410 also outputs this calculated signal that makes the DC component of the demodulated signal Sd zero to the sensor element 10. As a result, the effective spring constant of the sensor element 10 in the Y direction changes. Consequently, the second resonant frequency ω2 changes. Therefore, the controller 410 brings the second resonant frequency ω2 closer to the first resonant frequency ω1 by bringing the DC component of the demodulated signal Sd closer to zero. When the DC component of the demodulated signal Sd becomes zero, the second resonant frequency ω2 becomes the first resonant frequency ω1.

[0083] As described above, the control unit 40 of the angular velocity detection circuit 20 in the second embodiment is configured and performs processing. This second embodiment also achieves the same effects as the first embodiment.

[0084] (Third embodiment) In the third embodiment, the angular velocity detection circuit 20 includes a first control unit 41 and a second control unit 42 instead of the summing unit 35 and the control unit 40, as shown in Figure 9. Otherwise, it is the same as in the first embodiment.

[0085] Here, the resonant frequency of the vibration of the first oscillator 111 in the Y direction is denoted as the second resonant frequency ω2. The resonant frequency of the vibration of the second oscillator 112 in the Y direction is denoted as the third resonant frequency ω3.

[0086] The first control unit 41 then obtains sin(ω1×t) and cos(ω1×t) from the first vibration generation unit 21. The first control unit 41 also obtains a signal corresponding to the displacement of the first oscillator 111 in the Y direction from the first detection unit 31. Furthermore, the first control unit 41 controls the second resonant frequency ω2 based on these obtained signals.

[0087] For example, the first control unit 41 has a first phase comparison unit 401 and a first controller 411, as shown in Figure 10.

[0088] The first phase comparison unit 401 acquires sin(ω1×t) from the first vibration generation unit 21. The first phase comparison unit 401 also acquires a signal corresponding to the displacement of the first oscillator 111 in the Y direction from the first detection unit 31. Furthermore, the first phase comparison unit 401 includes a PLL, etc. Based on this, the first phase comparison unit 401 calculates the first phase difference Δθ1 of the acquired signal. The first phase comparison unit 401 also outputs a signal corresponding to this calculated first phase difference Δθ1 to the first controller 411, which will be described later. The first phase difference Δθ1 is the difference between the phase of sin(ω1×t) and the phase of the signal corresponding to the displacement of the first oscillator 111 in the Y direction.

[0089] Here, let's assume that the second resonant frequency ω2 coincides with the first resonant frequency ω1. In this case, the phase of the signal corresponding to the displacement of the first oscillator 111 in the Y direction and the phase of the signal that causes the first oscillator 111 and the second oscillator 112 to vibrate in the X direction, with a frequency of the first resonant frequency ω1 and opposite phases to each other, are the same. Therefore, in this case, the first phase difference Δθ1 becomes zero.

[0090] Therefore, the first controller 411 obtains a signal corresponding to the first phase difference Δθ1 from the first phase comparison unit 401. Furthermore, the first controller 411 calculates a signal that sets the first phase difference Δθ1 to zero by using the obtained signal corresponding to the first phase difference Δθ1 and PI control, etc. The first controller 411 also outputs this calculated signal that sets the first phase difference Δθ1 to zero to the sensor element 10. As a result, the effective spring constant of the sensor element 10 in the Y direction changes. Consequently, the second resonant frequency ω2 changes. Therefore, the first controller 411 brings the second resonant frequency ω2 closer to the first resonant frequency ω1 by bringing the first phase difference Δθ1 closer to zero. When the first phase difference Δθ1 becomes zero, the second resonant frequency ω2 becomes the first resonant frequency ω1.

[0091] Returning to Figure 9, the second control unit 42 acquires sin(ω1×t) and cos(ω1×t) from the first vibration generation unit 21. Furthermore, the second control unit 42 acquires a signal corresponding to the displacement of the second oscillator 112 in the Y direction from the second detection unit 32. The second control unit 42 also controls the third resonant frequency ω3 based on these acquired signals.

[0092] For example, the second control unit 42 has a second phase comparison unit 402 and a second controller 412, as shown in Figure 11.

[0093] The second phase comparison unit 402 acquires sin(ω1×t) from the first vibration generation unit 21. Furthermore, the second phase comparison unit 402 acquires a signal corresponding to the displacement of the second oscillator 112 in the Y direction from the second detection unit 32. The second phase comparison unit 402 also includes a PLL, etc. Based on this, the second phase comparison unit 402 calculates the second phase difference Δθ2 of these acquired signals. Furthermore, the second phase comparison unit 402 outputs a signal corresponding to this calculated second phase difference Δθ2 to the second controller 412, which will be described later. The second phase difference Δθ2 is the difference between the phase of sin(ω1×t) and the phase of the signal corresponding to the displacement of the second oscillator 112 in the Y direction.

[0094] Here, let's assume that the third resonant frequency ω3 coincides with the first resonant frequency ω1. In this case, the phase of the signal corresponding to the displacement of the second oscillator 112 in the Y direction and the phase of the signal that causes the first oscillator 111 and the second oscillator 112 to vibrate in the X direction, with a frequency of the first resonant frequency ω1 and opposite phases to each other, are the same. Therefore, in this case, the second phase difference Δθ2 becomes zero.

[0095] Therefore, the second controller 412 obtains a signal corresponding to the second phase difference Δθ2 from the second phase comparison unit 402. The second controller 412 also calculates a signal that sets the second phase difference Δθ2 to zero by using the obtained signal corresponding to the second phase difference Δθ2 and PI control, etc. Furthermore, the second controller 412 outputs this calculated signal that sets the second phase difference Δθ2 to zero to the sensor element 10. As a result, the effective spring constant of the sensor element 10 in the Y direction changes. Consequently, the third resonant frequency ω3 changes. Therefore, the second controller 412 brings the third resonant frequency ω3 closer to the first resonant frequency ω1 by bringing the second phase difference Δθ2 closer to zero. When the second phase difference Δθ2 becomes zero, the third resonant frequency ω3 becomes the first resonant frequency ω1.

[0096] As described above, the angular velocity detection circuit 20 of the third embodiment is configured. This third embodiment also provides the same effects as the first embodiment. Furthermore, the third embodiment also provides the effects described below.

[0097] [2] The angular velocity detection circuit 20 comprises a first control unit 41 and a second control unit 42. The first control unit 41 controls the second resonant frequency ω2 based on a signal corresponding to the displacement of the first vibrator 111 in the Y direction. The second control unit 42 controls the third resonant frequency ω3 based on a signal corresponding to the displacement of the second vibrator 112 in the Y direction. The signal corresponding to the displacement of the first vibrator 111 in the Y direction corresponds to the signal corresponding to the vibration of the first vibrator 111 when the first vibrator 111 and the second vibrator 112 are vibrating in the X and Y directions by the first vibration generating unit 21 and the second vibration generating unit 22. The signal corresponding to the displacement of the second vibrator 112 in the Y direction corresponds to the signal corresponding to the vibration of the second vibrator 112 when the first vibrator 111 and the second vibrator 112 are vibrating in the X and Y directions by the first vibration generating unit 21 and the second vibration generating unit 22.

[0098] As a result, the resonant frequency of the vibration of the first oscillator 111 in the Y direction and the resonant frequency of the vibration of the second oscillator 112 in the Y direction are controlled independently. Therefore, the resonant frequency of the vibration of the first oscillator 111 in the Y direction and the resonant frequency of the vibration of the second oscillator 112 in the Y direction tend to coincide with the first resonant frequency ω1. Consequently, the amplitude of the angular velocity of the sensor element 10 with respect to the Coriolis force acting on the first oscillator 111 and the second oscillator 112 in the Y direction tends to increase. Thus, the reduction in resolution in the calculation of angular velocity by the angular velocity detection circuit 20 is suppressed.

[0099] (Fourth Embodiment) In the fourth embodiment, the configuration and processing of the first control unit 41 and the second control unit 42 differ from those of the third embodiment. Otherwise, it is the same as the third embodiment.

[0100] Specifically, as shown in Figure 12, the first control unit 41 includes a first synchronous detection unit 421 instead of the first phase comparison unit 401.

[0101] The first synchronous detection unit 421 acquires cos(ω1×t) from the first vibration generation unit 21. Furthermore, the first synchronous detection unit 421 acquires a signal corresponding to the displacement of the first oscillator 111 in the Y direction from the first detection unit 31. The first synchronous detection unit 421 also includes a synchronous detection circuit, etc. As a result, the first synchronous detection unit 421 demodulates the signal corresponding to the displacement of the first oscillator 111 in the Y direction with a frequency and phase corresponding to cos(ω1×t). Furthermore, the first synchronous detection unit 421 outputs a first demodulated signal Sd1 to the first controller 411. The first demodulated signal Sd1 is a signal that has been demodulated with a frequency and phase corresponding to cos(ω1×t) from the signal corresponding to the displacement of the first oscillator 111 in the Y direction.

[0102] Here, when the second resonant frequency ω2 coincides with the first resonant frequency ω1, the signal corresponding to the displacement of the first oscillator 111 in the Y direction becomes a signal related to sin(ω1×t). Therefore, the DC component of the first demodulated signal Sd1 becomes zero.

[0103] Therefore, the first controller 411 acquires the first demodulated signal Sd1 from the first synchronous detection unit 421. The first controller 411 also uses the acquired first demodulated signal Sd1 and PI control, etc., to calculate a signal that makes the DC component of the first demodulated signal Sd1 zero. Furthermore, the first controller 411 outputs this calculated signal that makes the DC component of the first demodulated signal Sd1 zero to the sensor element 10. As a result, the effective spring constant of the sensor element 10 in the Y direction changes. Consequently, the second resonant frequency ω2 changes. Therefore, the first controller 411 brings the second resonant frequency ω2 closer to the first resonant frequency ω1 by bringing the DC component of the first demodulated signal Sd1 closer to zero. When the DC component of the first demodulated signal Sd1 becomes zero, the second resonant frequency ω2 becomes the first resonant frequency ω1.

[0104] As shown in Figure 13, the second control unit 42 includes a second synchronous detection unit 422 instead of the second phase comparison unit 402.

[0105] The second synchronous detection unit 422 acquires cos(ω1×t) from the first vibration generation unit 21. The second synchronous detection unit 422 also acquires a signal corresponding to the displacement of the second oscillator 112 in the Y direction from the second detection unit 32. Furthermore, the second synchronous detection unit 422 includes a synchronous detection circuit, etc. As a result, the second synchronous detection unit 422 demodulates the signal corresponding to the displacement of the second oscillator 112 in the Y direction with a frequency and phase corresponding to cos(ω1×t). The second synchronous detection unit 422 also outputs a second demodulated signal Sd2 to the second controller 412. The second demodulated signal Sd2 is a signal that has been demodulated with a frequency and phase corresponding to cos(ω1×t) from the signal corresponding to the displacement of the second oscillator 112 in the Y direction.

[0106] Here, when the third resonant frequency ω3 coincides with the first resonant frequency ω1, the signal corresponding to the displacement of the second oscillator 112 in the Y direction becomes a signal related to sin(ω1×t). Therefore, the DC component of the second demodulated signal Sd2 becomes zero.

[0107] Therefore, the second controller 412 acquires the second demodulated signal Sd2 from the second synchronous detection unit 422. Furthermore, the second controller 412 uses the acquired second demodulated signal Sd2 and PI control, etc., to calculate a signal that makes the DC component of the second demodulated signal Sd2 zero. The second controller 412 also outputs this calculated signal that makes the DC component of the second demodulated signal Sd2 zero to the sensor element 10. As a result, the effective spring constant of the sensor element 10 in the Y direction changes. Consequently, the third resonant frequency ω3 changes. Therefore, the second controller 412 brings the third resonant frequency ω3 closer to the first resonant frequency ω1 by bringing the DC component of the second demodulated signal Sd2 closer to zero. When the DC component of the second demodulated signal Sd2 becomes zero, the third resonant frequency ω3 becomes the first resonant frequency ω1.

[0108] As described above, the first control unit 41 and the second control unit 42 of the angular velocity detection circuit 20 of the fourth embodiment are configured and perform processing. This fourth embodiment also provides the same effects as the third embodiment.

[0109] (Fifth embodiment) In the fifth embodiment, as shown in Figure 14, the configuration of the sensor element 10 differs from that of the first embodiment. Furthermore, as shown in Figure 15, the angular velocity detection circuit 20 does not include a first detection unit 31, a second detection unit 32, an adder unit 35, and a subtractor unit 45. Other than these, it is the same as the first embodiment.

[0110] Returning to Figure 14, the sensor element 10 further comprises a fifth electrode 135, a sixth electrode 136, a seventh electrode 137, and an eighth electrode 138, in addition to the first electrode 131, the second electrode 132, the third electrode 133, and the fourth electrode 134.

[0111] The fifth electrode 135 is positioned in the Y direction opposite the portion of the first resonator 111 that is connected to the first elastic portion 121 in the Y direction. When the first resonator 111 vibrates in the Y direction, the distance between the fifth electrode 135 and the first resonator 111 changes, causing the fifth capacitance Cs5 to change. Furthermore, the fifth electrode 135 outputs a signal corresponding to the change in the fifth capacitance Cs5. The fifth capacitance Cs5 is the capacitance between the fifth electrode 135 and the fifth resonator.

[0112] Furthermore, the fifth electrode 135, like the first electrode 131, faces the first oscillator 111 in the Y direction. Therefore, when the first oscillator 111 vibrates in the Y direction, the sign of the change in the fifth capacitance Cs5 is considered to be the same as the sign of the change in the first capacitance Cs1.

[0113] The sixth electrode 136 faces the portion of the first resonator 111 that is connected to the second elastic portion 122 in the Y direction, in the Y direction. Therefore, the sixth electrode 136 faces the portion of the first resonator 111 that is opposite to the first electrode 131 and the fifth electrode 135, in the Y direction. Furthermore, when the first resonator 111 vibrates in the Y direction, the distance between the sixth electrode 136 and the first resonator 111 changes, causing the sixth capacitance Cs6 to change. The sixth electrode 136 also outputs a signal corresponding to the change in the sixth capacitance Cs6. The sixth capacitance Cs6 is the capacitance between the sixth electrode 136 and the first resonator 111.

[0114] Furthermore, the sixth electrode 136, like the second electrode 132, faces the first oscillator 111 in the Y direction. Therefore, when the first oscillator 111 vibrates in the Y direction, the sign of the change in the sixth capacitance Cs6 is considered to be the same as the sign of the change in the second capacitance Cs2.

[0115] The seventh electrode 137 is positioned in the Y direction opposite the portion of the second oscillator 112 that is connected to the third elastic portion 123 in the Y direction. When the seventh oscillator vibrates in the Y direction, the distance between the seventh electrode 137 and the second oscillator 112 changes, causing the seventh capacitance Cs7 to change. Furthermore, the seventh electrode 137 outputs a signal corresponding to the change in the seventh capacitance Cs7. The seventh capacitance Cs7 is the capacitance between the seventh electrode 137 and the second oscillator 112.

[0116] Furthermore, the seventh electrode 137, like the third electrode 133, faces the second oscillator 112 in the Y direction. Therefore, when the second oscillator 112 vibrates in the Y direction, the sign of the change in the seventh capacitance Cs7 is considered to be the same as the sign of the change in the third capacitance Cs3.

[0117] The eighth electrode 138 faces the portion of the second resonator 112 that is connected to the fourth elastic portion 124 in the Y direction, in the Y direction. Therefore, the eighth electrode 138 faces the portion of the second resonator 112 that is opposite to the third electrode 133 and the seventh electrode 137, in the Y direction. Furthermore, when the second resonator 112 vibrates in the Y direction, the distance between the eighth electrode 138 and the second resonator 112 changes, causing the eighth capacitance Cs8 to change. The eighth electrode 138 also outputs a signal corresponding to the change in the eighth capacitance Cs8. The eighth capacitance Cs8 is the capacitance between the eighth electrode 138 and the second resonator 112.

[0118] Furthermore, the eighth electrode 138, like the fourth electrode 134, faces the second oscillator 112 in the Y direction. Therefore, when the second oscillator 112 vibrates in the Y direction, the sign of the change in the eighth capacitance Cs8 is considered to be the same as the sign of the change in the fourth capacitance Cs4.

[0119] Furthermore, the second vibration generating unit 22 ensures that the phase of vibration of the first oscillator 111 in the Y direction is the same as the phase of vibration of the second oscillator 112 in the Y direction. In addition, the third elastic section 123 in the Y direction is located on a plane that passes through the first elastic section 121 in the Y direction and is parallel to the X direction. For these reasons, when the first oscillator 111 and the second oscillator 112 vibrate in the Y direction, the signs of the changes in the first capacitance Cs1, the third capacitance Cs3, the fifth capacitance Cs5, and the seventh capacitance Cs7 are the same. Also, the fourth elastic section 124 in the Y direction is located on a plane that passes through the second elastic section 122 in the Y direction and is parallel to the X direction. For these reasons, when the first oscillator 111 and the second oscillator 112 vibrate in the Y direction, the signs of the changes in the second capacitance Cs2, the fourth capacitance Cs4, the sixth capacitance Cs6, and the eighth capacitance Cs8 are the same.

[0120] Furthermore, the first electrode 131 and the third electrode 133 are connected via wiring (not shown). In addition, the second electrode 132 and the fourth electrode 134 are connected via wiring (not shown). Also, as described above, the sign of the change in the first capacitance Cs1 is the same as the sign of the change in the third capacitance Cs3. Furthermore, the sign of the change in the second capacitance Cs2 is the same as the sign of the change in the fourth capacitance Cs4.

[0121] Therefore, the signal from the circuit composed of the first electrode 131, second electrode 132, third electrode 133, and fourth electrode 134 corresponds to a signal obtained by adding the signal corresponding to the displacement of the first oscillator 111 in the Y direction and the signal corresponding to the displacement of the second oscillator 112 in the Y direction. Thus, the first electrode 131, second electrode 132, third electrode 133, and fourth electrode 134 perform the roles of the first detection unit 31, second detection unit 32, and summing unit 35. Furthermore, the signal from the circuit composed of the first electrode 131, second electrode 132, third electrode 133, and fourth electrode 134 is output to the control unit 40, as shown in Figure 15. The control unit 40 uses the signal from the circuit composed of the first electrode 131, second electrode 132, third electrode 133, and fourth electrode 134 to perform processing similar to that of the first embodiment. As a result, the control unit 40 controls the second resonant frequency ω2.

[0122] Returning to Figure 14, the fifth electrode 135 and the eighth electrode 138 are connected via wiring not shown. Furthermore, the sixth electrode 136 and the seventh electrode 137 are connected via wiring not shown. Also, the sign of the change in the fifth capacitance Cs5 is the opposite of the sign of the change in the sixth capacitance Cs6, and therefore the sign of the change in the eighth capacitance Cs8 is also the opposite. Furthermore, the sign of the change in the seventh capacitance Cs7 is the opposite of the sign of the change in the eighth capacitance Cs8, and therefore the sign of the change in the sixth capacitance Cs6 is also the opposite.

[0123] Therefore, the signal from the circuit composed of the fifth electrode 135, sixth electrode 136, seventh electrode 137, and eighth electrode 138 corresponds to a signal obtained by subtracting the signal corresponding to the displacement of the second oscillator 112 in the Y direction from the signal corresponding to the displacement of the first oscillator 111 in the Y direction. Thus, the fifth electrode 135, sixth electrode 136, seventh electrode 137, and eighth electrode 138 play the roles of the first detection unit 31, the second detection unit 32, and the subtraction unit 45. Furthermore, the signal from the circuit composed of the fifth electrode 135, sixth electrode 136, seventh electrode 137, and eighth electrode 138 is output to the angular velocity calculation unit 50, as shown in Figure 15. The angular velocity calculation unit 50 performs the same processing as in the first embodiment using the signal from the circuit composed of the fifth electrode 135, sixth electrode 136, seventh electrode 137, and eighth electrode 138. As a result, the angular velocity calculation unit 50 calculates the angular velocity of the sensor element 10.

[0124] As described above, the sensor element 10 using the angular velocity detection circuit 20 of the fifth embodiment is configured, and the angular velocity detection circuit 20 is configured. This fifth embodiment also provides the same effects as the first embodiment.

[0125] (Sixth Embodiment) In the sixth embodiment, as shown in Figure 16, the angular velocity detection circuit 20 further includes an amplitude control unit 55. Otherwise, it is the same as in the first embodiment.

[0126] The amplitude control unit 55 acquires the signal output from the second vibration generation unit 22 to the sensor element 10. The amplitude control unit 55 also acquires a signal from the summing unit 35 that is the sum of the signal corresponding to the displacement of the first vibrator 111 in the Y direction and the signal corresponding to the displacement of the second vibrator 112 in the Y direction. Furthermore, the amplitude control unit 55 includes a gain controller, etc. As a result, the amplitude control unit 55 controls the amplitude of the signal output from the second vibration generation unit 22 to the sensor element 10 so that the amplitude of the summed signal becomes constant. This causes the amplitude control unit 55 to make the amplitudes of the signal corresponding to the displacement of the first vibrator 111 in the Y direction and the signal corresponding to the displacement of the second vibrator 112 in the Y direction constant. Note that "constant" includes an error range.

[0127] As described above, the angular velocity detection circuit 20 of the sixth embodiment is configured. This sixth embodiment also provides the same effects as the first embodiment. Furthermore, the sixth embodiment also provides the effects described below.

[0128] [3] Here, disturbances may occur in the sensor element 10. If the frequency of the disturbance matches the first resonant frequency ω1, an error in the angular velocity due to the disturbance will occur.

[0129] In contrast, in the sixth embodiment, the angular velocity detection circuit 20 further includes an amplitude control unit 55. The amplitude control unit 55 controls the amplitude of the signal output from the second vibration generation unit 22 to the sensor element 10. As a result, the amplitude control unit 55 keeps the amplitude of the signal corresponding to the displacement of the first vibrator 111 in the Y direction and the amplitude of the signal corresponding to the displacement of the second vibrator 112 in the Y direction constant.

[0130] As a result, the amplitudes of the signals corresponding to the displacement of the first oscillator 111 in the Y direction and the signals corresponding to the displacement of the second oscillator 112 in the Y direction are kept constant. Therefore, when the signal corresponding to the displacement of the second oscillator 112 in the Y direction is subtracted from the signal corresponding to the displacement of the first oscillator 111 in the Y direction, disturbances are more easily removed along with the vibration component from the second vibration generating unit 22. Consequently, erroneous detection of angular velocity due to disturbances is suppressed.

[0131] (Other embodiments) This disclosure is not limited to the embodiments described above, and modifications can be made to these embodiments as appropriate. Furthermore, it goes without saying that, in each of the embodiments described above, the elements constituting the embodiment are not necessarily essential, except in cases where they are explicitly stated to be particularly essential or where they are clearly considered essential in principle.

[0132] The control unit, calculation unit, amplitude control unit, and method described in this disclosure may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit, calculation unit, amplitude control unit, and method described in this disclosure may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit, calculation unit, amplitude control unit, and method described in this disclosure may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0133] In each of the above embodiments, the signals corresponding to the vibration of the first vibrator 111 when the first vibrator 111 and the second vibrator 112 are vibrating in the X and Y directions are the signals corresponding to the change in the first capacitance Cs1 and the signals corresponding to the change in the second capacitance Cs2. In contrast, the signals corresponding to the vibration of the first vibrator 111 when the first vibrator 111 and the second vibrator 112 are vibrating in the X and Y directions are not limited to the signals corresponding to the change in the first capacitance Cs1 and the signals corresponding to the change in the second capacitance Cs2. For example, if the sensor element 10 is a piezoelectric element, the signals corresponding to the vibration of the first vibrator 111 when the first vibrator 111 and the second vibrator 112 are vibrating in the X and Y directions may be voltage signals output from the piezoelectric element.

[0134] Furthermore, when the first transducer 111 and the second transducer 112 are vibrating in the X and Y directions, the signals corresponding to the vibration of the second transducer 112 are defined as signals corresponding to the change in the third capacitance Cs3 and signals corresponding to the change in the fourth capacitance Cs4. However, the signals corresponding to the vibration of the second transducer 112 when the first transducer 111 and the second transducer 112 are vibrating in the X and Y directions are not limited to signals corresponding to the change in the third capacitance Cs3 and signals corresponding to the change in the fourth capacitance Cs4. For example, since the sensor element 10 is a piezoelectric element, the signals corresponding to the vibration of the second transducer 112 when the first transducer 111 and the second transducer 112 are vibrating in the X and Y directions may be voltage signals output from the piezoelectric element.

[0135] In each of the above embodiments, the signal output from the first vibration generating unit 21 to the sensor element 10 is a sine wave. However, the signal output from the first vibration generating unit 21 to the sensor element 10 is not limited to being a sine wave. The signal output from the first vibration generating unit 21 to the sensor element 10 may be a square wave, a triangular wave, a sawtooth wave, or the like.

[0136] In the sixth embodiment described above, the amplitude control unit 55 uses the signal from the second vibration generation unit 22 and the signal added by the summing unit 35 to keep the amplitudes of the signal corresponding to the displacement of the first vibrator 111 in the Y direction and the signal corresponding to the displacement of the second vibrator 112 in the Y direction constant. Alternatively, the amplitude control unit 55 may use the signals output from the first detection unit 31 and the second detection unit 32 instead of the signals added by the summing unit 35. Furthermore, the amplitude control unit 55 may use the signals output from the sensor element 10 to the angular velocity detection circuit 20, corresponding to the displacement of the first vibrator 111 in the Y direction and the signals corresponding to the displacement of the second vibrator 112 in the Y direction, instead of the signals added by the summing unit 35.

[0137] The above embodiments may be combined as appropriate. [Explanation of symbols]

[0138] 10 Sensor elements 111 First oscillator 112 Second oscillator 21 First vibration generation unit 22 Second vibration generation section 40 Control Unit 50 Angular velocity calculation section

Claims

1. An angular velocity detection circuit used in a sensor element (10) comprising a first vibrator (111) and a second vibrator (112) that vibrate in a first direction (X) and a second direction (Y) intersecting the first direction, and having a first resonant frequency (ω1) which is the resonant frequency of vibration in the first direction and a second resonant frequency (ω2) which is the resonant frequency of vibration in the second direction, A first vibration generating unit (21) that vibrates the first vibrator and the second vibrator in a first direction, A second vibration generating unit (22) that vibrates the first vibrator and the second vibrator in the second direction, A control unit (40) that controls the second resonant frequency, A calculation unit (50) calculates the angular velocity when the sensor element rotates around an axis extending in a third direction (Z) that intersects the first and second directions, Equipped with, The first vibration generating unit is A signal that causes the first oscillator to vibrate in the first direction, wherein the vibration has a frequency of the first resonant frequency, A signal that causes the second oscillator to vibrate in the first direction, wherein the vibration has a frequency of the first resonant frequency and a phase opposite to the phase of the vibration of the first oscillator in the first direction, The signal is output to the sensor element, By vibrating the first vibrator, a Coriolis force acting in the second direction is generated when the sensor element rotates around the axis extending in the third direction, thereby generating vibrations in the first vibrator that are in the second direction and have a frequency of the first resonant frequency. By vibrating the second vibrator, a Coriolis force acting in the second direction is generated when the sensor element rotates around the axis extending in the third direction, causing the second vibrator to vibrate in the second direction, having a frequency of the first resonant frequency and a phase opposite to the phase of the vibration of the first vibrator in the second direction due to the Coriolis force. The second vibration generating unit is, A signal that causes the first oscillator to vibrate in the second direction, wherein the vibration has a frequency of the first resonant frequency, A signal that causes the second oscillator to vibrate in the second direction, wherein the phase of the vibration of the first oscillator in the second direction by the second vibration generating unit corresponds to the phase of the vibration of the first oscillator in the second direction, The signal is output to the sensor element, The control unit controls the second resonant frequency based on the signals corresponding to the vibration of the first vibrator and the vibration of the second vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions, respectively, by the first vibration generating unit and the second vibration generating unit. The calculation unit is an angular velocity detection circuit that calculates the angular velocity based on the signal output from the first vibration generating unit to the sensor element, a signal obtained by subtracting the signal corresponding to the vibration of the second vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions by the first and second vibration generating units from the signal corresponding to the vibration of the first vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions by the first and second vibration generating units, and a cutoff frequency (fs).

2. The angular velocity detection circuit according to claim 1, wherein the control unit brings the second resonant frequency closer to the first resonant frequency.

3. The angular velocity detection circuit according to claim 1 or 2, wherein the control unit controls the second resonant frequency based on a phase difference (Δθ), which is the difference between the phase of a signal obtained by adding the signal corresponding to the vibration of the first vibrator and the signal corresponding to the vibration of the second vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions by the first vibrator generation unit and the second vibrator generation unit, and the phase of the signal output from the first vibrator generation unit to the sensor element.

4. The angular velocity detection circuit according to claim 3, wherein the control unit brings the second resonant frequency closer to the first resonant frequency by bringing the phase difference closer to zero.

5. The angular velocity detection circuit according to claim 1 or 2, wherein the control unit controls the second resonant frequency based on the value of the DC component of a demodulated signal (Sd), which is a signal obtained by adding a signal corresponding to the vibration of the first vibrator and a signal corresponding to the vibration of the second vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions by the first vibrator generation unit and the second vibrator generation unit, and demodulating the signal corresponding to the frequency and phase of the signal output from the second vibrator generation unit to the sensor element.

6. The angular velocity detection circuit according to claim 5, wherein the control unit brings the second resonant frequency closer to the first resonant frequency by bringing the value relating to the amplitude of the demodulated signal closer to zero.

7. The second resonant frequency is the resonant frequency of the vibration of the first oscillator in the second direction, If the resonant frequency of the vibration of the second oscillator in the second direction is the third resonant frequency (ω3), The control unit, Based on the signal corresponding to the vibration of the first vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions, respectively, the second resonant frequency is controlled. The angular velocity detection circuit according to claim 1 or 2, wherein the third resonant frequency is controlled based on a signal corresponding to the vibration of the second vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions, respectively, by the first vibrator generation unit and the second vibrator generation unit.

8. The control unit, Based on a first phase difference (Δθ1), which is the difference between the phase of the signal corresponding to the vibration of the first vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions by the first vibration generating unit and the phase of the signal output from the first vibration generating unit to the sensor element, the second resonant frequency is controlled. The angular velocity detection circuit according to claim 7, wherein the third resonant frequency is controlled based on a second phase difference (Δθ2), which is the difference between the phase of a signal corresponding to the vibration of the second vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions by the first vibrator generation unit and the second vibrator generation unit, and the phase of a signal output from the first vibrator generation unit to the sensor element.

9. The control unit, By bringing the first phase difference closer to zero, the second resonant frequency is brought closer to the first resonant frequency. The angular velocity detection circuit according to claim 8, wherein the third resonant frequency is brought closer to the first resonant frequency by bringing the second phase difference closer to zero.

10. The control unit, Based on the value of the DC component of the first demodulated signal (Sd1), which is a signal obtained by demodulating the signal corresponding to the vibration of the first vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions by the first vibration generating unit and the second vibration generating unit, the second resonant frequency is controlled. The angular velocity detection circuit according to claim 7, wherein the third resonant frequency is controlled based on the value of the DC component of a second demodulated signal (Sd2), which is a signal obtained by demodulating a signal corresponding to the frequency and phase of the signal output from the second vibration generating unit to the sensor element, with respect to a signal corresponding to the vibration of the second vibrator when the first vibrator and the second vibrator are vibrating in the first and second directions, respectively, by the first vibration generating unit and the second vibration generating unit.

11. The control unit, By bringing the value of the DC component of the first demodulated signal closer to zero, the second resonant frequency is brought closer to the first resonant frequency. The angular velocity detection circuit according to claim 10, wherein the value relating to the DC component of the second demodulated signal is brought closer to zero, thereby bringing the third resonant frequency closer to the first resonant frequency.

12. The angular velocity detection circuit according to claim 1 or 2, further comprising an amplitude control unit (55) that controls the amplitude of the signal output from the second vibration generating unit to the sensor element, thereby keeping the amplitudes of the signal corresponding to the vibration of the first vibrator and the signal corresponding to the vibration of the second vibrator constant when the first vibrator and the second vibrator are vibrating in the first and second directions, respectively, by the first vibration generating unit and the second vibration generating unit.

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