JP4600032B2 - Angular velocity detector - Google Patents

Description

  The present invention relates to an angular velocity detection device that measures an angular velocity by measuring a Coriolis force when an angular velocity due to an external force acts on a vibrating body that vibrates with a predetermined amplitude and period.

  In recent years, angular velocity detection devices using gyro sensors have been used in suspension and airbag control devices in automobiles, inertial navigation systems in aircraft, camera shake correction devices for cameras, and the like. As this type of angular velocity detection device, there is known a vibratory gyro sensor that measures angular velocity by measuring Coriolis force when an angular velocity due to an external force acts on a mass body vibrated with a predetermined amplitude and period ( For example, refer nonpatent literature 1.).

  FIG. 14 is a conceptual diagram for explaining a configuration of a gyro sensor according to the background art. The gyro sensor 101 shown in FIG. 14 has a vibration body 102 made of a substantially rectangular parallelepiped conductor, and a vibration in the X-axis direction when the X-axis is parallel to one side of the vibration body 102 as shown in FIG. Drive electrodes 103 and 104 disposed opposite to each other with the body 102 therebetween, and detection electrodes 105 and 106 disposed opposite to each other with the vibrating body 102 interposed in the Y-axis direction orthogonal to the X-axis. ing. The driving electrodes 103 and 104 and the detection electrodes 105 and 106 are respectively arranged so as to face one surface of the vibrating body 102 with an interval, and electrostatic capacitances C103, C104, C105, and C106 are respectively provided between the driving body 103 and the vibrating body 102. Is formed.

  FIG. 15 is an explanatory diagram for explaining the operation of the gyro sensor 101. In the gyro sensor 101 shown in FIG. 14, when the driving voltage Vd1 having the resonance frequency of the vibrating body 102 is applied to the driving electrode 103 and the driving voltage Vd2 having the opposite phase to the driving voltage Vd1 is applied to the driving electrode 104. A periodic electrostatic force is generated between the vibrating body 102 and the driving electrodes 103 and 104, and the vibrating body 102 vibrates along the X-axis direction. In this state, when an angular velocity R is applied to the gyro sensor 101 about an axis perpendicular to the paper surface, a Coriolis force is generated in the Y-axis direction, and the vibrating body 102 is displaced in the Y-axis direction according to the Coriolis force. When the vibrating body 102 is displaced in the Y-axis direction, the capacitances C105 and C106 between the vibrating body 102 and the detection electrodes 105 and 106 change. Accordingly, the capacitances C105 and C106 change according to the angular velocity applied to the gyro sensor 101.

  FIG. 16 is a block diagram showing an electrical configuration of the angular velocity detection device according to the background art. In FIG. 16, the gyro sensor 101 is shown as an equivalent circuit, and the description of the capacitance C103 (drive electrode 103) and the capacitance C104 (drive electrode 104) is omitted. 16 includes a gyro sensor 101, a carrier generation circuit 111, a current-voltage conversion circuit (hereinafter referred to as I / V conversion circuit) 112, a band-pass filter (hereinafter referred to as BPF) 113, and an amplifier 114. A synchronous detection circuit 115, an amplifier 116, and a lock-in amplifier 117.

  The carrier generation circuit 111 supplies a carrier signal Vc1 having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, to the capacitance C105, and outputs a carrier signal Vc2 having a phase opposite to that of the carrier signal Vc1 to the capacitance C106. To supply. In the equivalent circuit of the gyro sensor 101 shown in FIG. 16, the capacitances C105 and C106 are connected to the vibrating body 102, and the vibrating body 102 is connected to the I / V conversion circuit 112.

When the capacitances C105 and C106 are equal, that is, when the vibrating body 102 is positioned at the center of the detection electrodes 105 and 106, the carrier generation circuit 111 passes through the capacitance C105 to the I / V conversion circuit 112. The flowing current I ₁₀₅ and the current I ₁₀₆ flowing to the I / V conversion circuit 112 via the capacitance C ₁₀₆ are canceled out to be zero. Further, when an angular velocity is applied to the gyro sensor 101 and the position of the vibrating body 102 is displaced by the Coriolis force, the distance between the vibrating body 102 and the detection electrodes 105 and 106 changes, and the capacitances C105 and C106 are changed. the result of discrepancies, differences occur between the current I ₁₀₅ and the current I _106, detection current Iin corresponding to the difference between the current I ₁₀₅ and the current I ₁₀₆ is to flow into the I / V conversion circuit 112 Yes. That is, based on the detection current Iin flowing to the I / V conversion circuit 112, the displacement amount due to the Coriolis force of the vibrating body 102 can be detected.

  The I / V conversion circuit 112 converts the detection current Iin into a voltage signal and outputs it to the BPF 113. The BPF 113 passes the frequency component of 100 kHz from the voltage signal output from the I / V conversion circuit 112, that is, the frequency components of the carrier signals Vc1 and Vc2 to the amplifier 114 as the voltage signal Vx1.

FIG. 17 is an explanatory diagram for explaining the operation of the angular velocity detection device 100 shown in FIG. 16. FIG. 18 is a diagram showing carrier signals Vc1, Vc2 and output voltage signal Vx1 of BPF 113 in each state shown in FIG. First, as shown in FIG. 17A, in the state where the vibrating body 102 is positioned between the detection electrodes 105 and 106 (state 1), the facing distance between the vibrating body 102 and the detection electrodes 105 and 106 is as follows. Since they are equal, the capacitance C105 and the capacitance C106 are equal. As a result, the current I ₁₀₅ and the current I ₁₀₆ are canceled and the current Iin flowing from the vibrating body 102 to the I / V conversion circuit 112 becomes substantially zero. As a result, the output voltage signal Vx1 of the BPF 113 in the state 1 shown in FIG. Nearly zero.

Next, as shown in FIG. 17B, in the state where the vibrating body 102 is displaced in the direction of the detection electrode 105 due to the Coriolis force (state 2), the distance between the vibrating body 102 and the detection electrode 105 is the vibration body 102. Therefore, the electrostatic capacity C105 is larger than the electrostatic capacity C106. Then, since the current I ₁₀₅ becomes larger than the current I _106, the influence of the current I _{105 on} the current Iin increases, and the output voltage signal Vx1 of the BPF 113 is detected by the detection electrode 105 as shown by the state 2 in FIG. It has the same phase as the carrier signal Vc1 supplied to.

  Next, as shown in FIG. 17C, the vibrating body 102 returns to the state (state 3) located in the middle of the detection electrodes 105 and 106, and in the state 3 shown in FIG. The output voltage signal Vx1 of the BPF 113 is substantially zero.

Next, as illustrated in FIG. 17D, in a state where the vibrating body 102 is displaced in the direction of the detection electrode 106 due to the Coriolis force (state 4), the distance between the vibrating body 102 and the detection electrode 106 is as follows. Therefore, the capacitance C106 is larger than the capacitance C105. Then, since the current I ₁₀₆ becomes larger than the current I _105, the influence of the current I _{106 on} the current Iin increases, and the output voltage signal Vx1 of the BPF 113 is detected by the detection electrode 106 as shown by the state 4 in FIG. Are in phase with the carrier signal Vc2 being supplied to.

The voltage signal Vx1 is synchronously detected by the synchronous detection circuit 115, amplified by the amplifier 116, and synchronously detected by the lock-in amplifier 117, whereby a detection signal Sout indicating the angular velocity applied to the vibrating body 102 is output. It has come to be.
Technical Digest of the 17th Sensor Symposium 2000. pp. 249-254

  By the way, in the angular velocity detection device configured as described above, the vibrating body 102 is moved between the detection electrode 105 and the detection electrode 106 by Coriolis force acting on the vibrating body 102 due to the angular velocity applied to the vibrating body 102. The angular velocity applied to the vibrating body 102 is detected by detecting a difference between the capacitance C105 and the capacitance C106 that is displaced.

Therefore, in a state where the angular velocity is not applied to the vibrating body 102 and no Coriolis force is applied (hereinafter referred to as an initial state), the capacitance C105 and the capacitance C106 need to be equal. On the other hand, in the gyro sensor 101 as shown in FIG. 14, for example, the capacitances C105 and C106 have values in the picofarad order (10 ⁻¹² F order), whereas the amount of change in capacitance due to the Coriolis force is attrition. Farad order (10 ^-18 F order). Then, the error in the capacitance that is allowed in the initial state between the capacitance C105 and the capacitance C106 is 1/1000000 or less, and creating the capacitances C105 and C106 equally with such accuracy is as follows. For example, it is not easy to use silicon microfabrication technology.

  FIG. 19 shows a carrier signal Vc1 when there is a difference between the capacitance C105 and the capacitance C106 in the initial state, for example, when the capacitance C105 is larger than the capacitance C106 in the initial state. , Vc2 and the output voltage signal Vx1 of the BPF 113 and the signal Vx2 obtained by amplifying the output voltage signal Vx1 by the amplifier 114 and synchronously detecting it by the synchronous detection circuit 115.

  As shown in FIG. 19, when the capacitance C105 is larger than the capacitance C106 in the initial state, the output from the BPF 113 in a state where the vibrating body 102 is displaced toward the detection electrode 105 by the Coriolis force (state 2). The output voltage signal Vx1 to be output has a voltage amplitude larger than that of the output voltage signal Vx1 output from the BPF 113 when the vibrating body 102 is displaced in the direction of the detection electrode 105 due to the Coriolis force (state 4). Then, the output voltage signal Vx1 is amplified by the amplifier 114, and an offset voltage is generated in the signal Vx2 synchronously detected by the synchronous detection circuit 115. Further, the signal Vx2 is amplified by the amplifier 116 and is synchronously detected by the lock-in amplifier 117. The detected signal Sout has a disadvantage that the offset voltage generated in the signal Vx2 appears as a measurement error, resulting in a decrease in angular velocity detection accuracy.

  As a method of removing the offset voltage generated in the signal Vx2, for example, by inserting a high-pass filter or a band-pass filter between the synchronous detection circuit 115 and the amplifier 116, the offset voltage generated in the signal Vx2 is removed. Conceivable. However, even if the offset voltage generated in the signal Vx2 is removed using a filter, there are the following disadvantages.

  That is, in order to improve the S / N ratio (signal-to-noise ratio) in the detection signal Sout, it is desirable that the output voltage signal Vx1 of the BPF 113 is sufficiently amplified by the amplifier 114 and then input to the synchronous detection circuit 115. Since the synchronous detection circuit 115 functions as a steep bandpass filter for the signal band, if the input signal of the synchronous detection circuit 115 is amplified in the previous stage, the S / N ratio is improved and the angular velocity detection accuracy is improved. On the other hand, if the output signal of the synchronous detection circuit 115 is amplified at the subsequent stage, the noise component and the signal component are also amplified at the same time, resulting in a decrease in angular velocity detection accuracy.

  However, when there is a difference between the capacitance C105 and the capacitance C106 in the initial state, for example, when the capacitance C105 is larger than the capacitance C106 in the initial state, FIG. As shown, the voltage amplitude of the output voltage signal Vx1 output from the BPF 113 in the state 2 is larger than that of the output voltage signal Vx1 output from the BPF 113 in the state 4. Then, if the amplification factor of the amplifier 114 is increased to sufficiently amplify the output voltage signal Vx1 in the state 4, the output voltage of the amplifier 114 is saturated in the state 2. On the other hand, if the amplification factor of the amplifier 114 is set within a range where the output voltage signal Vx1 in the state 2 is not saturated, the output voltage signal Vx1 in the state 4 cannot be sufficiently amplified, and thus the S / N ratio in the detection signal Sout is improved. I can't let you.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide an angular velocity detection device capable of improving angular velocity detection accuracy.

In order to achieve the above-mentioned object, an angular velocity detection device according to one aspect of the present invention is arranged between first and second electrodes arranged to face each other, and between the first and second electrodes, A vibrating body that generates a first capacitance between the first electrode and a second capacitance between the first electrode and the second electrode, and the vibrating body that is the first and second electrodes a drive unit but that vibrates in the direction perpendicular to the direction opposite the first of said electrostatic capacity to the first electrode and the second electrode of the second capacitance, the frequency signals of opposite phases to each other A carrier signal supply unit that induces an induced current in the vibrator by supplying first and second detection voltages, respectively, and a difference between the first capacitance and the second capacitance In the state where the angular velocity is not applied to the vibrating body Of serial first or second capacitance, a capacitor the first or second detection voltage is supplied to the first or second electrode small electrostatic capacitance is generated is supplied, the vibration A superimposed voltage obtained by combining the induced current from the body and the current flowing through the capacitor into a superimposed voltage , and applied to the vibrating body based on the superimposed voltage output from the current-voltage converter. And an angular velocity detector that detects the angular velocity.

An angular velocity detection device according to another aspect of the present invention is arranged between a first electrode and a second electrode arranged opposite to each other, and between the first electrode and the second electrode, and between the first electrode and the first electrode. A vibrating body that generates a first capacitance and a second capacitance between the first electrode and the second electrode; and the vibrating body in a direction orthogonal to a direction in which the first and second electrodes face each other. First and second detection signals that are frequency signals having opposite phases to the drive unit to be oscillated, the first electrode of the first capacitance, and the second electrode of the second capacitance. A carrier signal supply unit that induces an induced current in the vibrating body by supplying a working voltage, and the first or second capacitance in a state where an angular velocity is not applied to the vibrating body, which is smaller The first supplied to the first or second electrode in which capacitance is generated Includes a capacitor to which a second detection voltage is supplied, a current-voltage conversion unit that converts a superimposed current obtained by combining an induced current from the vibrating body and a current flowing through the capacitor into a superimposed voltage, and the current-voltage conversion. An angular velocity detection unit that detects an angular velocity applied to the vibrating body based on the superimposed voltage output from the unit, and the first or second capacitance that generates a small capacitance among the first or second capacitance. A signal amplifying unit that amplifies the first or second detection voltage supplied to the second electrode and supplies the amplified voltage to the capacitor, and the amplification factor of the signal amplifying unit is an angular velocity applied to the vibrator It is characterized in that the superposed current is set to zero in a state where it is not performed .

In the angular velocity detection device described above, the signal according to the increase / decrease in the level of the superimposed current obtained by combining the induced current from the vibrating body and the current flowing through the capacitor in a state where no angular velocity is applied to the vibrating body. An amplification factor setting unit that performs a setting operation to increase or decrease the amplification factor of the amplification unit is further provided .

Furthermore, in the above-described angular velocity detection device, the superimposed signal amplification unit further includes a superimposed signal amplification unit that amplifies a voltage based on the superimposed voltage obtained by converting the superimposed current by the current-voltage conversion unit and outputs the amplified voltage to the angular velocity detection unit. Is characterized in that after the setting operation is executed by the amplification factor setting unit, an amplification factor for amplifying the voltage based on the superimposed voltage is increased .

In the above-described angular velocity detection device, the changeover switch unit further includes a changeover switch unit that selects one of the first and second detection voltages to be supplied to the capacitor, and a phase comparison unit. In the state where neither the first detection voltage nor the second detection voltage is selected, and no angular velocity is applied to the vibrating body, the carrier signal supply unit The first and second detection voltages, which are frequency signals having phases opposite to each other, are supplied to the first electrode and the second electrode of the second capacitance, respectively, thereby inducing the vibrator. Current is induced, the current-voltage conversion unit converts the induced current from the vibrating body into a voltage, and the phase comparison unit includes a voltage obtained by shifting the phase of the first detection voltage by 90 degrees and the current voltage Converted by the converter When the phases match, the changeover switch unit selects the second detection voltage, and when the phases do not match, the changeover switch unit selects the first detection voltage. The voltage is selected .

In the angular velocity detection device having such a configuration, the vibrating body is driven by the drive unit, and the first and second capacitances are generated between the vibrating body with the vibrating body sandwiched in a direction orthogonal to the vibration direction. Since the first and second electrodes are provided, when an angular velocity is applied to the vibrating body, a Coriolis force acts on the vibrating body to displace the vibrating body, and the opposing distance between the vibrating body and the first and second electrodes As a result, the first and second capacitances change. When the first and second detection voltages, which are frequency signals having opposite phases to each other, are supplied to the first and second capacitances, respectively, according to the difference between the first and second capacitances. The induced current is induced in the vibrating body. In this case, the difference of the first and second capacitance in the state where no angular velocity is applied to the vibrating body, it appears as an offset current in the induced signal, the capacitor, one of the first and second detection voltage since the detection voltage supplied to the electrostatic capacitance of the smaller of the first and second capacitance in the state where no angular velocity is applied to the vibrating body, it is superimposed on the induced current, the offset in the induced current The current is offset and a superimposed current is generated. Since the angular velocity applied to the vibrating body is detected by the angular velocity detector based on the superimposed current with the offset current cancelled, the angular velocity detection accuracy can be improved.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of the angular velocity detection device according to the first embodiment of the present invention. 1 includes an I / V conversion circuit 2, a first bandpass filter (hereinafter abbreviated as BPF) 3, an amplifier 4, a first synchronous detection circuit 5, an amplifier 6, a second BPF 7, A synchronous detection circuit 8, an amplifier 9, a drive signal generation circuit 10, a carrier generation circuit 11, which is an example of a carrier signal supply unit, a phase shifter 12, a gyro sensor 101, and a capacitor C1 are provided. The configuration of the gyro sensor 101 is the same as that of the gyro sensor 101 shown in FIG. In FIG. 1, the gyro sensor 101 is shown by an equivalent circuit. In the equivalent circuit of the gyro sensor 101 shown in FIG. 1, the capacitances C103, C104, C105, and C106 are connected to the vibrating body 102, and the vibrating body 102 is connected to the I / V conversion circuit 112. In this case, the capacitances C105 and C106 correspond to examples of the first and second capacitances in the claims, respectively, and the detection electrode 105 for generating the capacitance C105 and the detection for generating the capacitance C106. The electrode 106 corresponds to an example of each of the first and second electrodes in the claims.

  The drive signal generation circuit 10 supplies a drive voltage Vd1 having a resonance frequency (natural frequency) of the vibrating body 102 to the capacitance C103 (drive electrode 103), and drives the capacitance C104 (drive electrode 104). A driving voltage Vd2 having a phase opposite to that of the working voltage Vd1 is supplied. Thereby, as shown in FIG. 14, the drive signal generation circuit 10 has an electrostatic force acting between the driving electrode 103 and the vibrating body 102 and an electrostatic force acting between the driving electrode 104 and the vibrating body 102. The force is changed to a force in the opposite direction, and the direction is reversed according to the resonance frequency of the vibration body 102, thereby vibrating the vibration body 102 along the X-axis direction at the resonance frequency. The resonance frequency of the vibrating body 102 is, for example, 2.3 kHz. Further, the drive signal generation circuit 10 outputs the drive voltage Vd1 to the second synchronous detection circuit 8.

  In this case, the drive electrodes 103 and 104 and the drive signal generation circuit 10 correspond to an example of a drive unit in the claims. The driving unit is not limited to the example using the two driving electrodes 103 and 104, and may be configured to vibrate the vibrating body 102 with one driving electrode, for example. The drive unit is not limited to the example in which the vibrating body 102 is vibrated by electrostatic force, and may be configured to mechanically vibrate the vibrating body 102 using, for example, a motor or a solenoid.

The carrier generation circuit 11 supplies a carrier signal Vc1 (first detection signal) having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, to the capacitance C105 (detection electrode 105). A carrier signal Vc2 (second detection signal) having a phase opposite to that of the carrier signal Vc1 is supplied to the capacitance C106 (detection electrode 106). The frequencies of the carrier signals Vc1 and Vc2 are desirably two orders of magnitude higher than the resonance frequency of the vibrating body 102. When the angular velocity is applied to the vibrating body 102 and the position of the vibrating body 102 is displaced by the Coriolis force, the distance between the vibrating body 102 and the detection electrodes 105 and 106 changes, and the capacitance C105 and the capacitance C106. results discrepancies between the results is a difference between the current I ₁₀₅ and the current I _106, the detected current I ₀ (induced signal) corresponding to the difference between the current I ₁₀₅ and the current I ₁₀₆ is, vibrator 102 To the I / V conversion circuit 112.

Further, the carrier generation circuit 11 outputs the carrier signal Vc1 to the phase shifter 12. The phase shifter 12 shifts the phase of the carrier signal Vc1 output from the carrier generation circuit 11 by 90 degrees, and outputs the carrier signal Vc3 to the first synchronous detection circuit 5. Thus, the phase shifter 12 corresponds to the detected current I ₀ is 90 degrees leading phase than the carrier signal Vc1 by the capacitance C105 and the capacitance C106, similarly carrier signal Vc1 and the detected current I ₀ Advance the phase by 90 degrees.

Further, in an initial state in which no angular velocity is applied to the vibrating body 102 and no Coriolis force is applied, the capacitance C105 and the capacitance C106 are measured in advance in the manufacturing process, for example, and the capacitance value is smaller. For example, a capacitor C1 is connected in advance between the output terminal of the carrier generation circuit 11 and the input terminal of the I / V conversion circuit 2 for the carrier signal Vc1 supplied to the detection electrode 105 of the electrostatic capacitance C105. Then, for example, the current I ₁ (superimposed signal) generated by superimposing the carrier signal Vc1 on the detection current I ₀ flowing from the vibrating body 102 to the I / V conversion circuit 2 by the capacitor C1 is the I / V conversion circuit 2. Is output.

  The capacitance value of the capacitor C1 is set to be equal to the difference between the capacitance values of the electrostatic capacitances C105 and C106 measured in advance. For example, a variable capacitor may be used as the capacitor C1, and the capacitance may be set so that the difference between the capacitance values of the capacitances C105 and C106 is equal to the capacitance. Note that the capacitor C1 is not limited to an example constituted by a single discrete component. For example, when the I / V conversion circuit 2 is integrated, the capacitor C1 is integrated in the same integrated circuit as the I / V conversion circuit 2. May be. Alternatively, as shown in FIG. 2, the capacitor C1 is formed by connecting a plurality of series circuits of capacitors and switching elements in parallel, and the capacitances C105 and C106 in which the capacitance of the entire capacitor C1 is measured in advance. The switching elements may be turned on / off so as to be equal to the difference between the capacitance values. For example, the capacitance of the capacitor C1 is determined by measuring the difference between the capacitance values of the capacitances C105 and C106 for a plurality of angular velocity detection devices 1, and setting the average value as the capacitance of the capacitor C1. Also good.

The I / V conversion circuit 2 is a circuit unit that converts a current signal into a voltage signal. The I / V conversion circuit 2 combines a detection current I ₀ from the vibrating body 102 and a current I _C1 that flows from the carrier generation circuit 11 through the capacitor C1. ₁ is converted into a voltage and output to the first BPF 3 as a voltage signal Sv.

  The first BPF 3 reflects the frequency component of the carrier signal output from the carrier generation circuit 11 of the voltage signal Sv output from the I / V conversion circuit 2, for example, a frequency component of 100 kHz (the angular velocity applied to the vibrating body 102 is reflected). Frequency component) is selectively passed and output to the amplifier 4 as a voltage signal Vo1. The amplifier 4 amplifies the voltage signal Vo1 output from the first BPF 3 and outputs the amplified voltage signal Vo1 to the first synchronous detection circuit 5. The first synchronous detection circuit 5 performs synchronous detection on the signal output from the amplifier 4 based on the carrier signal Vc3 output from the phase shifter 12, and outputs the signal to the amplifier 6 as the voltage signal Vo3. The amplifier 6 amplifies the voltage signal Vo3 from the first synchronous detection circuit 5 and outputs it to the second BPF 7.

  The second BPF 7 selectively passes a resonance frequency of the vibrating body 102, for example, a frequency component of 2.3 kHz, and outputs the voltage signal Vo4 to the second synchronous detection circuit 8. The second synchronous detection circuit 8 synchronously detects the voltage signal Vo4 obtained from the second BPF 7 based on the drive voltage Vd1 output from the drive signal generation circuit 10, and generates a voltage signal Vo5 representing the angular velocity as a DC voltage. Output to the amplifier 9. The amplifier 9 amplifies the voltage signal Vo5 output from the second synchronous detection circuit 8 and outputs a detection signal Sout indicating the displacement of the vibrating body 102, that is, the angular velocity applied to the gyro sensor 101.

Then, the first synchronous detection circuit 5, the amplifier 6, the second BPF 7, the second synchronous detection circuit 8, and the amplifier 9 applied to the vibrating body 102 based on the current I ₁ (superimposed signal) generated by the capacitor C ₁ . An example of an angular velocity detector that detects an angular velocity and outputs a detection signal Sout representing the angular velocity is configured.

  Next, the operation of the angular velocity detection device 1 configured as described above will be described. First, the drive signal generation circuit 10 supplies the drive voltage Vd1 at the resonance frequency of the vibrating body 102 to the drive electrode 103 of the electrostatic capacity C103, and the drive voltage to the drive electrode 104 of the electrostatic capacity C104. A driving voltage Vd2 having a phase opposite to that of Vd1 is supplied. As a result, the electrostatic force acting between the driving electrode 103 and the vibrating body 102 and the electrostatic force acting between the driving electrode 104 and the vibrating body 102 are reversed in force, and the direction vibrates. By being inverted according to the resonance frequency of the body 102, the vibration body 102 vibrates at the resonance frequency, for example, 2.3 kHz, along the X-axis direction.

Next, the carrier generation circuit 11 supplies a carrier signal Vc1 having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, to the detection electrode 105 of the capacitance C105, and the carrier signal Vc1. The carrier signal Vc2 having the opposite phase is supplied to the detection electrode 106 of the capacitance C106. When an angular velocity is applied to the vibrating body 102, the position of the vibrating body 102 is displaced by the Coriolis force, and the distance between the vibrating body 102 and the detection electrodes 105 and 106 changes to change the electrostatic capacity C 105 and static electricity. capacitance C106 results discrepancies between the current difference is generated between the I ₁₀₅ and the current I _106, the detected current I ₀ is the I / V conversion circuit corresponding to the difference between the current I ₁₀₅ and the current I ₁₀₆ It flows to 2.

FIG. 3 is a signal waveform diagram for explaining the operation of the angular velocity detection device 1. Note that the detection current I ₀ and the current I ₁ shown in FIG. 3 are signal waveforms obtained by extracting a frequency component of a carrier signal, for example, a frequency component of 100 kHz, for the sake of simplicity. First, for example, when there is a difference between the capacitance C105 and the capacitance C106 in the initial state due to an error in manufacturing accuracy in manufacturing, for example, the capacitance C105 in the initial state is more than the capacitance C106. If the vibration body 102 is displaced in the direction of the detection electrode 105 by the Coriolis force (state 2), the detection current I ₀ output from the vibration body 102 is in the direction of the detection electrode 106 by the Coriolis force. The current value increases from the detected current I ₀ output from the vibrating body 102 in the state displaced to (4).

Next, the current I _C1 is superimposed on the detection current I ₀ output from the vibrating body 102 by the capacitor C1. In this case, since the capacitance of the capacitor C1 is set to be equal to the difference between the capacitance values of the capacitances C105 and C106 in the initial state, the current I _C1 flowing through the capacitor _C1 is the current I ₁₀₅ in the initial state. and corresponding to a difference (offset) between the current I _106. Therefore, a current (hereinafter referred to as an offset current) based on the difference between the electrostatic capacitance C105 and the electrostatic capacitance C106 in the initial state is canceled by the current I _C1 , and the current I ₁ shown in FIG. Input to the conversion circuit 2. As shown in FIG. 3, the current I ₁ in the state 2 is generated by the capacitor C1, the current I ₁ generated by the capacitor C1 in the state 4, shows a substantially equal peak current value.

Next, the current I ₁ generated by the capacitor C1 is converted into a voltage signal Sv by the I / V conversion circuit 2 and output to the first BPF 3. The first BPF 3 reflects the frequency component of the carrier signal output from the carrier generation circuit 11 out of the voltage signal Sv output from the I / V conversion circuit 2, for example, the frequency component of 100 kHz (the angular velocity applied to the vibrating body 102 is reflected. Frequency component) is selectively passed and output to the amplifier 4 as the voltage signal Vo1, amplified by the amplifier 4, and output to the first synchronous detection circuit 5 as the voltage signal Vo2.

In this case, it indicates substantially the same peak current value to the current I ₁ generated by the capacitor C1 at a current I ₁ and state 4 that is generated by the capacitor C1 in the state 2, as shown in FIG. 3, the voltage in the state 2 The signal Vo1 and the voltage signal Vo1 in the state 4 show substantially the same peak current value. Then, as in the angular velocity detection device 100 shown in FIG. 16, when the amplification factor of the amplifier 114 is increased to sufficiently amplify the output voltage signal Vx1 in the state 4, the output voltage signal Vx1 in the state 2 is saturated, If the amplification factor of the amplifier 114 is set within a range in which the output voltage signal Vx1 in 2 does not saturate, the output voltage signal Vx1 in state 4 cannot be sufficiently amplified, and therefore the S / N ratio cannot be improved. Nothing. The angular velocity detection device 1 shown in FIG. 1 can increase the amplification factor of the amplifier 4 within a range in which the voltage signal Vo2 in the state 2 and the voltage signal Vo2 in the state 4 are not saturated before the first synchronous detection circuit 5. Therefore, the S / N ratio in the detection signal Sout can be improved.

  FIG. 4 is a signal waveform diagram for explaining the operation of the first synchronous detection circuit 5. First, the first synchronous detection circuit 5 multiplies the voltage signal Vo2 output from the amplifier 4 and the carrier signal Vc3 output from the phase shifter 12 to generate a multiplication signal VA. That is, the first synchronous detection circuit 5 outputs a voltage signal Vo2 as it is if the carrier signal Vc3 is a positive potential, for example, using a multiplier, and inverts the polarity of the voltage signal Vo2 if the carrier signal Vc3 is a negative potential. Output. Then, as shown in FIG. 4, the voltage signal Vo2 is on the positive potential side if the voltage signal Vo2 and the carrier signal Vc3 are in phase, and on the negative potential side if the voltage signal Vo2 and the carrier signal Vc3 are in reverse phase. And the multiplication signal VA is generated. In this case, since the voltage signal Vo2 and the carrier signal Vc3 are in the same phase in the state 2 and the voltage signal Vo2 and the carrier signal Vc3 are in the opposite phase in the state 4, the voltage signal Vo2 is in the positive potential side in the state 2. In state 4, it is folded back to the negative potential side. The frequency of the multiplication signal VA is twice the frequency of the carrier signal Vc3 and the voltage signal Vo2.

  Next, the envelope of the multiplication signal VA is acquired by the first synchronous detection circuit 5 and output to the amplifier 6 as the voltage signal Vo3. Specifically, for example, the first synchronous detection circuit 5 passes the multiplication signal VA through a low-pass filter having a frequency smaller than the frequency of the multiplication signal VA and having a cutoff frequency equal to or higher than the resonance frequency of the vibrating body 102. Thus, the voltage signal Vo3 is generated. In this case, it is desirable that the cutoff frequency of the low-pass filter is, for example, 1/10 or less of the frequency of the multiplication signal VA and 10 times or more of the resonance frequency of the vibrating body 102.

Then, the voltage signal Vo3 is a voltage signal having the resonance frequency of the vibrating body 102 and having an amplitude corresponding to the difference between the current I ₁₀₅ and the current I ₁₀₆ generated by the displacement of the vibrating body 102 due to the Coriolis force. Since the offset current based on the difference between the capacitance C105 and the capacitance C106 in the initial state is canceled by the current I _C1 and then input to the I / V conversion circuit 2 as the current I ₁ , Even if the current I ₁ is converted into the voltage signal Sv by the I / V conversion circuit 2 and converted into the voltage signal Vo3 through the first BPF 3, the amplifier 4, and the first synchronous detection circuit 5, the voltage signal Vo3 is related to the background art. The offset voltage is not generated unlike the output signal Vx2 of the synchronous detection circuit 115, the offset voltage in the detection signal Sout is suppressed, and the angular velocity detection accuracy can be improved.

  Next, the amplifier 6 amplifies the voltage signal Vo3 and outputs the amplified voltage signal Vo3 to the second BPF 7. The second BPF 7 filters the voltage signal Vo3 and outputs the voltage signal Vo4 to the second synchronous detection circuit 8. FIG. 5 is a signal waveform diagram for explaining the operation of the second synchronous detection circuit 8. First, the second synchronous detection circuit 8 multiplies the voltage signal Vo4 output from the amplifier 6 and the drive voltage Vd1 output from the drive signal generation circuit 10 to generate a multiplication signal VB. That is, the second synchronous detection circuit 8 outputs the voltage signal Vo4 as it is when the driving voltage Vd1 is a positive potential using a multiplier, for example, and changes the polarity of the voltage signal Vo4 when the driving voltage Vd1 is a negative potential. Invert and output.

  In this case, the voltage signal Vo4 is a positive potential in the state 2 and a negative potential in the state 4. On the other hand, the driving voltage Vd1 is a positive potential in the state 2 and a negative potential in the state 4. Then, the voltage signal Vo4 is folded back to the positive potential side in the state 4 by the second synchronous detection circuit 8, and the multiplication signal VB becomes a positive potential signal in the states 2 and 4.

  Next, the multiplication signal VB is smoothed by the second synchronous detection circuit 8 and output to the amplifier 9 as the voltage signal Vo5. Specifically, the second synchronous detection circuit 8 performs smoothing by filtering the multiplication signal VB using, for example, a low-pass filter having a cutoff frequency close to DC, and generates a voltage signal Vo5. Then, the amplifier 9 amplifies the voltage signal Vo5 and outputs a detection signal Sout representing the angular velocity.

  As described above, the angular velocity detection device 1 shown in FIG. 1 can improve the S / N ratio in the detection signal Sout by increasing the amplification factor of the amplifier 4 and suppress the offset voltage in the detection signal Sout. Thus, the detection accuracy of the angular velocity can be improved.

(Second Embodiment)
Next, an angular velocity detection device according to the second embodiment of the present invention will be described. FIG. 6 is a block diagram showing an example of the configuration of the angular velocity detection device 1a according to the second embodiment of the present invention. The angular velocity detection device 1a shown in FIG. 6 differs from the angular velocity detection device 1 shown in FIG. 1 in the following points.
That is, in the angular velocity detection device 1a shown in FIG. 6, a signal amplifier 13 having a variable amplification factor is interposed between the carrier generation circuit 11 and the capacitor C1. Then, in an initial state in which no angular velocity is applied to the vibrating body 102 and no Coriolis force is applied, for example, the capacitances C105 and C106 are measured in advance in the manufacturing process, and the capacitance value that is smaller, for example, electrostatic The output terminal of the carrier generation circuit 11 for the carrier signal Vc1 supplied to the capacitor C105 is connected to the amplifier 13, and the carrier signal Vc1 is amplified by the amplifier 13 and supplied to the capacitor C1.

Since the other configuration is the same as that of the angular velocity detection device 1 shown in FIG. 1, the description thereof will be omitted, and the characteristic points of the present embodiment will be described below. As described above, in the angular velocity detection device 1 shown in FIG. 1, the capacitance of the capacitor C1 is set to be equal to the difference between the capacitance values of the capacitances C105 and C106, and the current I flowing through the capacitor C1. _{By making C1} equal to the offset current, the offset current is canceled by the current I _C1 . However, if there is an error in the capacitance value of the capacitor C1, a difference is generated between the offset current and the current I _C1, and an offset voltage in the detection signal Sout is generated by a current corresponding to the difference. For example, when the capacitor C1 is configured by an integrated circuit, it is not easy to configure the capacitor C1 with high accuracy, and therefore, an offset voltage in the detection signal Sout is likely to occur.

Therefore, in the angular velocity detection device 1a shown in FIG. 6, in the initial state where the angular velocity is not applied to the vibrator 102, the signal amplifier is set so that the current I _C1 is equal to the offset current and the current I ₁ (superimposed signal) is zero. The amplification factor of 13 is set in advance, for example, in the manufacturing process. In this case, for example, by setting the amplification factor of the signal amplifier 13 to the detection signal Sout obtained based on the current I ₁ to zero, it may be a current I ₁ to zero.

  FIG. 7 is a circuit diagram showing an example of the configuration of the amplifier 13. The amplifier 13 shown in FIG. 7 is composed of, for example, a non-inverting amplifier, the inverting input terminal of the operational amplifier 131 is connected to the ground via the resistor R1, and a series circuit of the resistor R2 and the variable resistor VR1 is used as a feedback resistor. The operational amplifier 131 is connected between the output terminal and the inverting input terminal, the non-inverting input terminal of the operational amplifier 131 is connected to the carrier generation circuit 11, and the output terminal of the operational amplifier 131 is connected to the capacitor C1. Then, the amplification factor of the amplifier 13 is set by setting the resistance value of the variable resistor VR1. The variable resistor VR1 may set a resistance value by, for example, laser trimming.

Thus, for example, in the manufacturing process, the amplification factor of the signal amplifier 13 is set in advance so that the current I ₁ (superimposed signal) is zero in a state where the angular velocity is not applied to the vibrating body 102, thereby causing the current flowing through the capacitor C 1. since the I _C1 can be canceled by the current I _C1 of the offset current by equal offset current, even if there is an error in the capacitance value of the capacitor C1 is canceled by the current I _C1 of the offset current, the detection signal Sout It is possible to improve the angular velocity detection accuracy by suppressing the offset voltage at.

(Third embodiment)
Next, an angular velocity detection device according to the third embodiment of the present invention will be described. FIG. 8 is a block diagram showing an example of the configuration of an angular velocity detection device 1b according to the third embodiment of the present invention. The angular velocity detection device 1b shown in FIG. 8 is configured to automatically select a carrier signal supplied to the smaller one of the capacitance values C105 and C106 and supply the carrier signal to the signal amplifier 13. The angular velocity detection device 1b shown in FIG. 8 differs from the angular velocity detection device 1a shown in FIG. 6 in the following points. That is, in the angular velocity detection device 1 b shown in FIG. 8, the changeover switch 14 (changeover switch unit) is interposed between the carrier generation circuit 11 and the signal amplifier 13. Further, the phase comparison circuit which compares the phase of the carrier signal Vc3 output from the phase shifter 12 and the voltage signal Vo2 output from the amplifier 4 and outputs a signal indicating the comparison result as the switching control signal S1 of the changeover switch 14. 15 (phase comparison unit).

  The changeover switch 14 selects one of the carrier signals Vc1 and Vc2 output from the carrier generation circuit 11 according to the changeover control signal S1 output from the phase comparison circuit 15 and supplies the signal to the signal amplifier 13 It is.

Since the other configuration is the same as that of the angular velocity detection device 1a shown in FIG. 6, the description thereof will be omitted, and the operation of the present embodiment will be described below. First, in a state where no angular velocity is applied to the vibrating body 102, for example, when a user turns on a power switch (not shown), an operation power supply voltage is supplied to each part of the angular velocity detection device 1b, and the angular velocity detection device 1b is activated. Then, a carrier signal Vc1 having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, is supplied from the carrier generation circuit 11 to the capacitance C105 (detection electrode 105) and the carrier signal Vc1. A carrier signal Vc2 having a phase opposite to that of is supplied to the capacitance C106 (detection electrode 106). If there is a difference between the electrostatic capacitance C105 and C106, difference occurs between the current I ₁₀₅ and the current I _106, the detection current I ₀ corresponding to a difference between the current I ₁₀₅ and the current I ₁₀₆ It flows to the I / V conversion circuit 2. In this case, the phase of the current I ₀ is higher than the voltage of the carrier signal (hereinafter referred to as the dominant carrier signal) applied to the larger one of the capacitances C105 and C106 of the carrier signals Vc1 and Vc2. The phase is advanced by 90 degrees.

The current I ₀ is converted into the voltage signal Sv by the I / V conversion circuit 2, filtered by the first BPF 3, amplified by the amplifier 4, converted into the voltage signal Vo 2, and output to the first synchronous detection circuit 5 and the phase comparison circuit 15. Therefore, the phase of the voltage signal Vo2 is 90 degrees ahead of the phase of the dominant carrier signal. On the other hand, the carrier signal Vc1 output from the carrier generation circuit 11 is advanced in phase by 90 degrees by the phase shifter 12, and is output to the first synchronous detection circuit 5 and the phase comparison circuit 15 as the carrier signal Vc3.

  FIG. 9 is a block diagram illustrating an example of the configuration of the phase comparison circuit 15. The phase comparison circuit 15 shown in FIG. 9 outputs a multiplication signal S2 obtained by multiplying the voltage signal Vo2 and the carrier signal Vc3 to the low-pass filter 152, and smoothes the multiplication signal S2 to switch the switching control signal. And a low-pass filter 152 that outputs S1.

  10 and 11 are explanatory diagrams for explaining the operation of the phase comparison circuit 15. First, in the initial state, when the capacitance C105 is smaller than the capacitance C106, the carrier signal Vc3 output from the phase shifter 12 and the voltage signal Vo2 output from the amplifier 4 as shown in FIG. Is opposite in phase and does not match. Then, the multiplication signal S2 obtained by multiplying the carrier signal Vc3 and the voltage signal Vo2 by the multiplication circuit 151 is a signal obtained by folding the signal waveform on the positive potential side in the voltage signal Vo2 to the negative potential side. Then, the multiplication signal S2 is smoothed by the low-pass filter 152, so that the changeover control signal S1 is converted to a negative direct current voltage and output to the changeover switch 14, and the changeover switch 14 is transferred to the capacitance C105 having a small capacitance value. It is switched to the supplied carrier signal Vc1 side.

  On the other hand, in the initial state, when the capacitance C106 is smaller than the capacitance C105, the carrier signal Vc3 output from the phase shifter 12 and the voltage signal Vo2 output from the amplifier 4 as shown in FIG. And have the same phase and the same phase. Then, the multiplication signal S2 obtained by multiplying the carrier signal Vc3 and the voltage signal Vo2 by the multiplication circuit 151 is a signal obtained by folding the negative potential side signal waveform of the voltage signal Vo2 to the positive potential side. Then, the multiplication signal S2 is smoothed by the low-pass filter 152, so that the changeover control signal S1 is converted to a positive direct current voltage and output to the changeover switch 14, and the changeover switch 14 is transferred to the capacitance C106 having a small capacitance value. It is switched to the supplied carrier signal Vc2.

  Thus, the phase comparison circuit 15 detects the smaller one of the capacitances C105 and C106, and sets the changeover switch 14 to supply the carrier signal supplied to the smaller capacitance value to the signal amplifier 13. For example, in the manufacturing process, the capacitances C105 and C106 are measured in advance, the smaller one of the capacitance values is examined in advance, and the carrier signal supplied to the smaller capacitance value is supplied to the signal amplifier 13. The operation of switching to supply becomes unnecessary, and the manufacturing process of the angular velocity detection device 1b can be simplified.

  Note that the angular velocity detection device 1b shown in FIG. 8 may be configured to directly supply the output signal of the changeover switch 14 to the capacitor C1 without including the amplifier 13.

(Fourth embodiment)
Next, an angular velocity detection device according to the fourth embodiment of the present invention will be described. FIG. 12 is a block diagram showing an example of the configuration of an angular velocity detection device 1c according to the fourth embodiment of the present invention. The angular velocity detection device 1c shown in FIG. 12 is different from the angular velocity detection device 1b shown in FIG. 8 in the following points. That is, the angular velocity detection device 1c shown in FIG. 12 includes an auto gain controller (hereinafter referred to as AGC) 16 which is an example of a signal amplification unit instead of the amplifier 13. The AGC 16 is configured such that the amplification factor is set according to the absolute value voltage of the switching control signal S1 output from the phase comparison circuit 15 which is an example of the amplification factor setting unit.

  Since the other configuration is the same as that of the angular velocity detection device 1b shown in FIG. First, in an initial state where no angular velocity is applied to the vibrating body 102, for example, when a user turns on a power switch (not shown), an operation power supply voltage is supplied to each part of the angular velocity detection device 1c, and the angular velocity detection device 1c When activated, the switching control signal S1 is supplied to the changeover switch 14 by the phase comparison circuit 15 in the same manner as the angular velocity detection device 1b shown in FIG. 8, and the capacitance of the capacitances C105 and C106 is changed by the changeover switch 14. The carrier signal supplied to the smaller value is supplied to the AGC 16.

Next, the gain of the AGC 16 is set according to the absolute value voltage of the switching control signal S1 output from the phase comparison circuit 15. Specifically, the phase comparison circuit 15 multiplies the voltage signal Vo2 and the carrier signal Vc3, smoothes them, and outputs the switching control signal S1. Then, since the carrier signal Vc3 is a signal obtained by shifting the phase of the carrier signal Vc1 output from the carrier generation circuit 11 by 90 degrees by the phase shifter 12, the signal level is constant. On the other hand, the current I ₁ in the initial state, that is, the state where the angular velocity is not applied to the vibrating body 102 is equal to the offset current, and the voltage signal Vo2 is a signal generated based on the current I _1. The voltage corresponds to the current.

Therefore, the absolute value of the switching control signal S1 that is smoothed by the phase comparison circuit 15 multiplied by the carrier signal Vc3 having a constant voltage level and the voltage signal Vo2 that is a voltage corresponding to the offset current is the offset current (initial value). The voltage corresponds to the current I ₁ ) in the state. Then, the absolute value of the switching control signal S1 obtained by the phase comparison circuit 15 in the initial state represents an insufficient amount of the current I _C1 flowing through the capacitor C1 so as to cancel the offset current. Therefore, the AGC 16 increases or decreases the amplification factor according to the increase or decrease of the absolute value of the switching control signal S1. That AGC16, by increasing or decreasing the amplification factor in accordance with the increase or decrease in the current I ₁ in the initial state, is adapted to hold together so as to set the amplification factor for the current I ₁ to zero offset the offset current ing.

Thus, the angular rate sensor 1c shown in FIG. 12, the AGC 16, it is possible to set the amplification factor to the current I ₁ to zero, for example in the manufacturing process, the amplifier in order to advance current I ₁ to zero The work of setting the amplification factor of 13 becomes unnecessary, and the manufacturing process of the angular velocity detection device 1c can be simplified.

The electrostatic capacitances C105 and C106 change due to environmental changes such as ambient temperature and humidity, aging deterioration, etc., but the angular velocity detection device 1c shown in FIG. Since the amplification factor can be set to make I ₁ zero, even if the capacitances C105 and C106 in the initial state change, the offset voltage in the detection signal Sout is suppressed and the angular velocity detection accuracy is suppressed. Can be improved.

The example in which the amplification factor of the AGC 16 is set based on the absolute value of the switching control signal S1 obtained by the phase comparison circuit 15 is shown. However, the amplification factor of the AGC 16 is the signal that reflects the current I _1. For example, it may be configured to be set based on the voltage signal Vo2 and the detection signal Sout in the initial state.

(Fifth embodiment)
Next, an angular velocity detection device according to a fifth embodiment of the present invention will be described. FIG. 13 is a block diagram showing an example of the configuration of an angular velocity detection device 1d according to the fifth embodiment of the present invention. The angular velocity detection device 1d shown in FIG. 13 is different from the angular velocity detection device 1c shown in FIG. 12 in the following points. That is, the angular velocity detection device 1 d shown in FIG. 13 includes an AGC 17 that is an example of a superimposed signal amplification unit instead of the amplifier 4. The AGC 17 amplifies the voltage signal Vo1, which is a signal based on the current I ₁ generated by the capacitor C1, and outputs the amplified voltage signal Vo1 to the first synchronous detection circuit 5 which is an example of the angular velocity detection unit. The AGC 17 decreases the amplification factor when the absolute value voltage of the switching control signal S1 output from the phase comparison circuit 15 increases, and increases the amplification factor and maintains the amplification factor when the absolute value voltage of the switching control signal S1 decreases. It has come to be.

Since the other configuration is the same as that of the angular velocity detection device 1c shown in FIG. 12, the description thereof is omitted, and the operation of this embodiment will be described below. As described above, the S / N ratio in the detection signal Sout is increased by increasing the amplification factor of the AGC 17 in a range in which the voltage signal Vo2 in the state 2 and the voltage signal Vo2 in the state 4 are not saturated in the previous stage of the synchronous detection circuit 5. Can be improved. However, since the capacity change caused to the capacitance C105 and C106 in response to the Coriolis force acting on the vibrating body 102 in response to the acceleration is very small, the current generated based on a difference in capacitance C105 and C106 I ₁ and the current I _The voltage signal Vo1 generated based on 1 is also a minute signal. Then, in order to improve the S / N ratio in the detection signal Sout, it is necessary to increase the amplification factor of the AGC 17 that amplifies the voltage signal Vo1 in the previous stage of the synchronous detection circuit 5 and outputs it as the voltage signal Vo2.

On the other hand, when the amplification factor of AGC 16 is not yet set, the offset current is not sufficiently canceled out, so that current I ₁ increases. Therefore, voltage signal Vo ₁ generated based on current I ₁ also increases. In a state where the gain of the AGC 17 is extremely increased to improve the S / N ratio in Sout, the voltage signal Vo2 output from the AGC 17 is saturated beyond the operating voltage range of the AGC 17.

  Therefore, in the angular velocity detection device 1d shown in FIG. 13, in the initial state where the angular velocity is not applied to the vibrating body 102, for example, when the user turns on a power switch (not shown), the operation power supply voltage is applied to each part of the angular velocity detection device 1d. Is supplied, and the angular velocity detection device 1d is activated. Then, the switching control signal S1 is output to the AGC 17 by the phase comparison circuit 15 by the same operation as the angular velocity detection device 1c shown in FIG. In this case, since the amplification factor of the AGC 16 is not yet set, the voltage signals Vo1 and Vo2 increase, and the absolute value voltage of the switching control signal S1 output from the phase comparison circuit 15 increases. Will be reduced.

  This suppresses the voltage signal Vo2 output from the AGC 17 from being saturated beyond the operating voltage range of the AGC 17 in a state where the gain of the AGC 16 is not yet set.

  On the other hand, when the gain of the AGC 16 is set to cancel the offset current by the same operation as that of the angular velocity detection device 1c shown in FIG. 12, the voltage signals Vo1 and Vo2 decrease and the switching output from the phase comparison circuit 15 Since the absolute value voltage of the control signal S1 decreases, the amplification factor of the AGC 17 is increased, and the S / N ratio of the detection signal Sout when the angular velocity is applied to the vibrating body 102 can be improved.

In this case, the AGC 17 amplifies the voltage signal Vo1 generated based on the current I ₁ when the absolute value voltage of the switching control signal S1 is reduced by setting the amplification factor of the AGC 16 to sufficiently cancel the offset current. The rate is set to increase.

  Thereby, since the gain of AGC 17 can be set in accordance with the setting state of the gain in AGC 16, the gain of AGC 16 can be increased without saturating voltage signal Vo2 before the gain of AGC 16 is set. After the offset current is set to cancel, that is, when the angular velocity detection operation is performed, the amplification factor of the AGC 17 can be increased, and the S / N ratio of the detection signal Sout can be improved.

  In addition, although the amplification factor of AGC17 showed the example set according to the absolute value voltage of switching control signal S1 output from the phase comparison circuit 15, in order to cancel offset current according to switching control signal S1, for example A setting detector that detects that the gain of the AGC 16 has been set may be provided so that the gain of the AGC 17 is increased when the setting detector detects that the gain of the AGC 16 has been set. .

  Further, in the angular velocity detection device 1a shown in FIG. 6, the angular velocity detection device 1b shown in FIG. 8, the angular velocity detection device 1c shown in FIG. 12, and the angular velocity detection device 1d shown in FIG. 14 shows an example in which the switch switching setting at 14 and the amplification factor setting at AGCs 16 and 17 are executed when each angular velocity detection device is activated. For example, a timer may be provided to perform these setting operations periodically. For example, an operation switch that receives an operation instruction from a user may be provided, and these setting operations may be performed when an instruction for these settings is received by the operation switch.

It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 1st Embodiment of this invention. FIG. 2 is a circuit diagram illustrating an example of a configuration of a capacitor illustrated in FIG. 1. It is a signal waveform diagram for demonstrating operation | movement of the angular velocity detection apparatus shown in FIG. It is a signal waveform diagram for demonstrating operation | movement of the 1st synchronous detection circuit shown in FIG. FIG. 6 is a signal waveform diagram for explaining the operation of the second synchronous detection circuit shown in FIG. 1. It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 2nd Embodiment of this invention. FIG. 7 is a circuit diagram illustrating an example of a configuration of an amplifier illustrated in FIG. 6. It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows an example of a structure of the phase comparison circuit shown in FIG. FIG. 9 is an explanatory diagram for describing an operation of the phase comparison circuit illustrated in FIG. 8. FIG. 9 is an explanatory diagram for describing an operation of the phase comparison circuit illustrated in FIG. 8. It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 4th Embodiment of this invention. It is a block diagram which shows an example of a structure of the angular velocity detection apparatus which concerns on the 5th Embodiment of this invention. It is a conceptual diagram for demonstrating the structure of the gyro sensor which concerns on background art. It is explanatory drawing for demonstrating operation | movement of the gyro sensor shown in FIG. It is a block diagram which shows the electrical constitution of the angular velocity detection apparatus which concerns on background art. It is explanatory drawing for demonstrating operation | movement of the angular velocity detection apparatus shown in FIG. It is explanatory drawing for demonstrating operation | movement of the angular velocity detection apparatus shown in FIG. It is explanatory drawing for demonstrating operation | movement of the angular velocity detection apparatus shown in FIG.

Explanation of symbols

1, 1a, 1b, 1c, 1d Angular velocity detector 2 I / V conversion circuit 3 1st BPF
4, 6, 9 Amplifier 5 1st synchronous detection circuit 7 2nd BPF
8 Second synchronous detection circuit 10 Drive signal generation circuit 11 Carrier generation circuit 12 Phase shifter 13 Amplifier 14 Changeover switch 15 Phase comparison circuit 101 Gyro sensor 102 Vibrating body 103, 104 Drive electrodes 105, 106 Detection electrodes C105, C106 Electrostatic capacity

Claims (5)

First and second electrodes disposed opposite to each other;
A vibrator that is arranged between the first and second electrodes and generates a first capacitance between the first electrode and the second electrode, and generates a second capacitance between the second electrode and the first electrode. When,
A drive unit that vibrates the vibrating body in a direction orthogonal to a direction in which the first and second electrodes face each other;
First and second detection voltages, which are frequency signals of opposite phases, are supplied to the first electrode of the first capacitance and the second electrode of the second capacitance, respectively. A carrier signal supply section for inducing an induced current in the vibrator,
The first or second capacitance having a capacitance substantially the same as a difference between the first capacitance and the second capacitance, and an angular velocity is not applied to the vibrating body. A capacitor supplied with the first or second detection voltage supplied to the first or second electrode in which a small capacitance is generated ,
A current-voltage converter that converts a superimposed current obtained by combining the induced current from the vibrating body and the current flowing through the capacitor into a superimposed voltage;
Based on the superimposed voltage output from the current-voltage converter, an angular velocity detector that detects an angular velocity applied to the vibrating body;
An angular velocity detection device comprising: First and second electrodes disposed opposite to each other;
A vibrator that is arranged between the first and second electrodes and generates a first capacitance between the first electrode and the second electrode, and generates a second capacitance between the second electrode and the first electrode. When,
A drive unit that vibrates the vibrating body in a direction orthogonal to a direction in which the first and second electrodes face each other;
First and second detection voltages, which are frequency signals of opposite phases, are supplied to the first electrode of the first capacitance and the second electrode of the second capacitance, respectively. A carrier signal supply section for inducing an induced current in the vibrator,
Of the first or second capacitance in a state where no angular velocity is applied to the vibrating body, the first or second electrode supplied to the first or second electrode in which a small capacitance is generated. A capacitor to which a detection voltage is supplied;
A current-voltage converter that converts a superimposed current obtained by combining the induced current from the vibrating body and the current flowing through the capacitor into a superimposed voltage;
Based on the superimposed voltage output from the current-voltage converter, an angular velocity detector that detects an angular velocity applied to the vibrating body;
Of the first or second capacitance, the first or second detection voltage supplied to the first or second electrode that generates a small capacitance is amplified and supplied to the capacitor. A signal amplifier, and
An amplification factor of the signal amplification unit is set to make the superimposed current zero in a state where no angular velocity is applied to the vibrating body. Setting to increase / decrease the amplification factor of the signal amplification unit according to increase / decrease of the level of the superimposed current obtained by synthesizing the induced current from the vibration body and the current flowing through the capacitor in the state where no angular velocity is applied to the vibration body The angular velocity detection device according to claim 2, further comprising an amplification factor setting unit that performs an operation. A superimposed signal amplification unit that amplifies a voltage based on the superimposed voltage obtained by converting the superimposed current by the current-voltage conversion unit and outputs the amplified voltage to the angular velocity detection unit;
The angular velocity detection device according to claim 3, wherein the superposition signal amplification unit increases the amplification factor for amplifying a voltage based on the superposition voltage after the setting operation is performed by the amplification factor setting unit. A changeover switch unit that selects one of the first and second detection voltages to be supplied to the capacitor;
A phase comparison unit;
In a state where the changeover switch unit has not selected either of the first and second detection voltages and no angular velocity is applied to the vibrating body, the carrier signal supply unit is configured to output the first static voltage. By supplying the first and second detection voltages, which are frequency signals having opposite phases to each other, to the first electrode of the capacitance and the second electrode of the second capacitance, Inducing an induced current in the vibrator,
The current-voltage converter converts the induced current from the vibrating body into a voltage,
The phase comparison unit compares the phase of the voltage obtained by shifting the phase of the first detection voltage by 90 degrees with the voltage converted by the current-voltage conversion unit, and when the phases match, the changeover switch unit The second detection voltage is selected, and when the phases do not match, the changeover switch unit is allowed to select the first detection voltage. Angular velocity detection device.

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