JP4600031B2 - Angular velocity detector - Google Patents

Description

  The present invention relates to an angular velocity detection device for measuring an angular velocity by measuring a Coriolis force when an angular velocity due to an external force is applied to a vibrating body applying a prescribed vibration.

  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 vibration type gyro sensor that measures angular velocity by measuring Coriolis force when an angular velocity due to an external force acts on a mass body that is applying a prescribed vibration (for example, a patent) Reference 1).

FIG. 8 is a conceptual diagram for explaining the configuration of a gyro sensor according to the background art (see, for example, Patent Document 2) . The gyro sensor 101 shown in FIG. 8 has one side of the vibrating body 102 when the X axis is parallel to one side of the vibrating body 102 as shown in FIG. And a driving electrode 103 disposed opposite to each other in the X-axis direction, and detection electrodes 105 and 106 disposed facing each other with the vibrating body 102 interposed therebetween in the Y-axis direction orthogonal to the X-axis. I have. The drive electrode 103 and the detection electrodes 105 and 106 are arranged to face each other with a distance from the vibrating body 102, and electrostatic capacitances C 103, C 105, and C 106 are formed between the driving electrode 103 and the detection electrodes 105 and 106.

  FIG. 9 is an explanatory diagram for explaining the operation of the gyro sensor 101. In the gyro sensor 101 shown in FIG. 8, when an AC voltage is applied to the driving electrode 103, a periodic electrostatic force is generated between the vibrating body 102 and the driving electrode 103, and the vibrating body 102 extends along the X-axis direction. Vibrate. 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. Therefore, the capacitances C105 and C106 change according to the angular velocity applied to the gyro sensor 101 if the vibration velocity of the vibrating body 102 is constant.

  Here, since the displacement in the Y-axis direction due to the Coriolis force generated by the angular velocity is proportional to the vibration velocity in the X-axis direction, it is necessary to keep the vibration speed of the vibrating body 102 large and constant. For this purpose, it is desirable to vibrate the vibrating body 102 at a specific resonance frequency. In general, it is known that an object can be vibrated at a resonance frequency by vibrating the object using a signal whose phase is shifted by 90 degrees from a signal waveform representing the displacement of the object. Therefore, conventionally, a detection signal indicating the mechanical displacement of the vibrating body 102 in the X-axis direction when the vibrating body 102 is vibrated is phase-shifted by 90 degrees and supplied to the driving electrode 103 as a driving voltage. The vibrating body 102 is resonated at the resonance frequency.

  FIG. 10 is a block diagram showing an electrical configuration of the angular velocity detection device according to the background art. In FIG. 10, the gyro sensor 101 is shown by an equivalent circuit. An angular velocity detection apparatus 100 shown in FIG. 10 includes a gyro sensor 101, a carrier generation circuit 111, an I / V converter 112, a bandpass filter (hereinafter abbreviated as BPF) 113, an amplifier 114, a synchronous detection circuit 115, a BPF 116, and A drive signal generator 117 is provided.

  The drive signal generator 117 vibrates the vibrating body 102 by supplying an AC voltage having a resonance frequency in the vibrating body 102 to the capacitance C103 as a driving voltage. The resonance frequency of the vibrating body 102 is, for example, about 1 to 9 kHz. The carrier generation circuit 111 supplies a carrier signal having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, to the capacitances C105 and C106 with a phase difference of 180 degrees. In the equivalent circuit of the gyro sensor 101 shown in FIG. 10, the capacitances C103, C105, and C106 are connected to the vibrating body 102, and the vibrating body 102 is connected to the I / V converter 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 converter 112. The flowing current I ₁₀₅ and the current I ₁₀₆ flowing to the I / V converter 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. results discrepancies, differences occurs between the current I ₁₀₅ and the current I _106, detection current I ₁ corresponding to a difference between the current I ₁₀₅ and the current I ₁₀₆ is to flow into the I / V converter 112 ing. That is, based on the detected current I ₁ flowing to the I / V converter 112, the displacement amount due to the Coriolis force of the vibrating body 102 can be detected.

On the other hand, when a driving voltage is supplied from the driving signal generator 117 to the driving electrode 103, a current I ₁₀₃ flows from the driving signal generator 117 to the vibrating body 102 via the capacitance C ₁₀₃ . In this case, the current I ₁₀₃ is a signal component that is superimposed when the vibration body 102 vibrates and the distance between the vibration body 102 and the driving electrode 103 changes, and thus the capacitance C103 changes, that is, the vibration body 102. And a signal component indicating the mechanical displacement of the vibrating body 102 in the X-axis direction (hereinafter referred to as a vibration component) and a signal component (hereinafter referred to as the drive voltage passing through the capacitance C103). Called a driving voltage component).

Then, a current obtained by adding the detection current I ₁ and the current I ₁₀₃ is converted into a voltage signal by the I / V converter 112, and the frequency of the carrier signal, for example, 100 kHz, that is, the detection current I ₁ is determined by the BPF 113. The detected frequency component is output to the amplifier 114, amplified by the amplifier 114, synchronously detected based on the carrier signal by the synchronous detection circuit 115, and the detection signal Sout indicating the displacement amount of the vibrating body 102, that is, the angular velocity applied to the gyro sensor 101. Is output.

On the other hand, the output signal of the I / V converter 112 is a vibration detection signal Sd in which the frequency component in the vicinity of the resonance frequency (for example, 2 kHz) of the vibrating body 102 by the BPF 116, that is, the frequency component corresponding to the current I103 indicates the displacement of the vibrating body 102. And the vibration detection signal Sd is supplied as a drive voltage to the drive electrode 103 by shifting the phase by 90 degrees by the drive signal generator 117, so that the vibrating body 102 has a resonance frequency. It is designed to vibrate.
JP-A-8-247767 JP 2000-283767 A

By the way, in the angular velocity detecting device configured as described above, the phase of the vibration detection signal Sd obtained based on the current I ₁₀₃ is shifted by 90 degrees and supplied to the driving electrode 103 as a driving voltage. The drive voltage supplied to the current I ₁₀₃ also includes a vibration component and a drive voltage component included in the current I ₁₀₃ .

  FIG. 11 is a signal waveform diagram for explaining the vibration detection signal Sd detected by the angular velocity detection device 100 configured as described above. In FIG. 11, the vibration component in the vibration detection signal Sd is indicated by a solid vibration component signal 121, and the drive voltage component in the vibration detection signal Sd is indicated by a broken drive voltage component signal 122. As shown in FIG. 11, the vibration component signal 121 and the drive voltage component signal 122 are signals having the same frequency and different phases. The vibration detection signal Sd is a signal obtained by combining the vibration component signal 121 and the drive voltage component signal 122.

FIG. 12 is a diagram illustrating the frequency characteristics of the vibration component signal 121. 12A shows the relationship between the frequency of the vibration component signal 121 and the amplitude displacement amount of the vibrating body 102, and FIG. 12B shows the relationship between the frequency and the phase displacement amount in the vibration component signal 121. Yes. As shown in FIG. 12A, when the frequency of the vibration component signal 121 becomes the resonance frequency f ₀ of the vibration body 102, the amplitude displacement amount of the vibration body 102 becomes maximum. 12B, the phase of the vibration component signal 121 changes according to the frequency of the vibration component signal 121, and the frequency of the vibration component signal 121 becomes the resonance frequency f ₀ of the vibration body 102. The amount of phase displacement is 90 degrees. Therefore, the vibration body 102 can be vibrated at the resonance frequency by shifting the phase of the vibration component signal 121 by 90 degrees and supplying it to the drive electrode 103 as a drive voltage.

FIG. 13 is a diagram illustrating the frequency characteristics of the drive voltage component signal 122. 13A shows the relationship between the frequency of the drive voltage component signal 122 and the amplitude displacement amount of the vibrating body 102, and FIG. 13B shows the relationship between the frequency and the phase displacement amount in the drive voltage component signal 122. Show. As shown in FIGS. 13A and 13B, the amplitude displacement amount and the phase change amount of the vibrating body 102 are constant even if the frequency of the vibration component signal 121 changes. Therefore, there is no correlation between the driving voltage component signal 122 and the resonance frequency f ₀ of the vibrating body 102, and the phase of the driving voltage component signal 122 is shifted by 90 degrees and supplied to the driving electrode 103 as a driving voltage. However, the vibrating body 102 cannot be vibrated at the resonance frequency.

  Therefore, in order to stably vibrate the vibrating body 102 at the resonance frequency, the detection signal indicating the mechanical displacement of the vibrating body 102 in the X-axis direction when the vibrating body 102 is vibrated, that is, the vibration component signal 121 is 90. The phase needs to be shifted and supplied to the driving electrode 103 as a driving voltage.

  However, since the vibration detection signal Sd includes the vibration component signal 121 and the drive voltage component signal 122, the vibration detection signal Sd is phase-shifted by 90 degrees and supplied to the drive electrode 103 as a drive voltage. However, the vibration body 102 cannot be stably vibrated at the resonance frequency, and therefore the displacement amount in the Y-axis direction due to the Coriolis force based on the angular velocity applied to the vibration body 102 is not stable, and the displacement amount in the Y-axis direction. There is a disadvantage that the accuracy of the detection signal Sout representing the angular velocity output in accordance with is reduced.

  In this case, it is conceivable to separate the vibration component signal 121 from the vibration detection signal Sd using a filter. However, since the vibration component signal 121 and the drive voltage component signal 122 have the same frequency, the vibration detection signal Sd is filtered from the vibration detection signal Sd. It is difficult to separate the vibration component signal 121 using

  The present invention has been made in view of such problems, and an object of the present invention is to provide an angular velocity detection device that can improve the accuracy of angular velocity detection by vibrating a vibrating body at a resonance frequency. .

In order to achieve the above-described object, an angular velocity detection device according to one aspect of the present invention includes an electrode and a vibrating body disposed to face the electrode, and the angular velocity detection device includes an angular velocity on the vibrating body. The angular velocity is detected based on the Coriolis force acting on the vibrating body when a voltage is applied, and a capacitance formed by the electrode and the vibrating body and a driving voltage are supplied to the electrode. the drive signal generating unit for vibrating the vibrating body, by driving voltage from the driving signal generator is supplied, an inverted signal output unit outputs an inverted voltage of the opposite polarity to the drive voltages by the An inverted voltage output from the inverted signal output unit is supplied, and a capacitor having substantially the same capacitance as the capacitance, and a current flowing from the drive signal generating unit to the vibrating body via the capacitance. Yes, In response to a current including a vibration component, which is a signal component indicating mechanical displacement of the vibrating body when the body is vibrated, and a driving voltage component, which is a signal component generated when the driving voltage passes through the capacitance A current-voltage conversion unit that converts a superimposed current obtained by adding a current output through the capacitor into a superimposed voltage, and the drive signal generation unit outputs the superimposed voltage output from the current-voltage conversion unit. A feature is that a signal in which the phase of the vibration component is shifted by 90 degrees is supplied to the electrode as a driving voltage .

In the above-described angular velocity detection device, the inversion signal output unit is characterized in that an inversion voltage gain is variable.

An angular velocity detection device according to another aspect of the present invention includes an electrode and a vibrating body disposed to face the electrode, and the angular velocity detection device is configured to apply the vibrating body when an angular velocity is applied to the vibrating body. The angular velocity is detected on the basis of the Coriolis force acting on the electrode, and further, the capacitance formed by the electrode and the vibrating body, and the drive for vibrating the vibrating body by supplying a driving voltage to the electrode A signal generation unit, an inverted signal output unit that outputs an inverted voltage having a polarity opposite to that of the drive voltage by supplying a drive voltage from the drive signal generation unit, and an inversion output from the inverted signal output unit A capacitor to which a voltage is supplied, and a current component that flows from the drive signal generator to the vibrating body via the capacitance, and a signal component that indicates mechanical displacement of the vibrating body when the vibrating body is vibrated so A superimposed current obtained by adding a current output via the capacitor to a current including a driving voltage component that is a signal component generated when the vibration component and the driving voltage pass through the capacitance is a superimposed voltage. And a drive signal generation unit that supplies a signal obtained by shifting the phase of the vibration component of the superimposed voltage output from the current / voltage conversion unit by 90 degrees to the electrode as a drive voltage. The inverted signal output unit is characterized in that the gain of the inverted voltage is made variable.

Furthermore, the above-described angular velocity detection device further includes an amplification factor setting unit that sets the amplification factor in the inverted signal output unit, and the amplification factor setting unit includes a vibration component of the superimposed voltage output from the current-voltage conversion unit. A setting operation for setting an amplification factor in the inverted signal output unit is performed so as to minimize the level of.

In the angular velocity detection device described above, when the setting operation is performed, the amplification factor setting unit sets the frequency of the driving voltage supplied from the driving signal generating unit to a frequency different from the resonance frequency of the vibrating body. It is characterized by that.

And in the above-mentioned angular velocity detecting device, it further comprises a superimposed signal amplification unit that amplifies the vibration component of the superimposed voltage output from the current-voltage conversion unit and supplies the amplified component to the drive signal generation unit, A signal obtained by shifting the phase of the voltage amplified by the superimposed signal amplifying unit by 90 degrees is supplied to the electrode as a driving voltage , and the superimposed signal amplifying unit is configured to execute the setting operation by the amplification factor setting unit. The amplification factor for amplifying the vibration component of the superimposed voltage is increased.

  In the angular velocity detecting device having such a configuration, the vibrating body vibrates due to the electrostatic force generated by supplying the periodic signal to the electrode by the drive signal generating unit, and the vibrating body vibrates in this way, When the capacitance changes, a signal in which a signal component indicating a mechanical displacement of the vibrating body is superimposed on a periodic signal applied to the vibrating body via the capacitance is induced as an induced signal in the vibrating body. Then, a signal indicating the mechanical displacement of the vibrating body is obtained by subtracting the periodic signal component included in the induced signal by superimposing the inverted signal having the opposite polarity to the periodic signal on the induced signal induced in the vibrating body by the capacitor. A superimposed signal having components is generated. Further, the drive signal generation unit supplies a signal obtained by shifting the phase of the superimposed signal indicating the mechanical displacement of the vibrating body by 90 degrees to the electrode as a periodic signal, so that the vibrating body vibrates at the resonance frequency. When the vibrating body vibrates at the resonance frequency, the vibration speed of the vibrating body is stabilized, and when the angular velocity is applied to the vibrating body, the stability of the Coriolis force acting on the vibrating body is improved. The accuracy of the angular velocity detected based on 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 converter 2, a bandpass filter (hereinafter abbreviated as BPF) 3, an amplifier 4, a synchronous detection circuit 5, a BPF 6, a drive signal generator 7, a capacitor C1, and an inversion. An inverter 8, a carrier generation circuit 9, and a gyro sensor 101, which are examples of a signal output unit, are provided. In FIG. 1, the gyro sensor 101 is shown by an equivalent circuit. When the angular velocity is applied to the vibrating body 102 by the I / V converter 2, BPF 3, amplifier 4, synchronous detection circuit 5, drive signal generator 7, carrier generation circuit 9, and gyro sensor 101, the vibrating body 102 An example of the angular velocity detection unit that detects the angular velocity based on the Coriolis force acting on is configured. Further, the driving electrode 103 in the gyro sensor 101 shown in FIG. 8 corresponds to an example of an electrode in the claims. Since the configuration of the gyro sensor 101 is the same as that of the gyro sensor 101 shown in FIGS. 8 and 10, the description thereof is omitted.

  The drive signal generator 7 is configured using, for example, a phase shift circuit using an all-pass filter, a PLL (Phase-Locked Loop) circuit, or the like, and is driven by shifting the phase of the vibration detection signal Sd output from the BPF 6 by 90 degrees. By supplying to the electrode 103 (capacitance C103), a driving voltage Vd (periodic signal) that is an AC voltage having a resonance frequency in the vibrating body 102 is generated, and the vibrating body 102 is vibrated at the resonance frequency. The resonance frequency of the vibrating body 102 is, for example, 2.3 kHz. Further, the drive signal generator 7 outputs the drive voltage Vd to the inverter 8. The carrier generation circuit 9 supplies a carrier signal having a predetermined frequency for capacitance detection, for example, a frequency of 100 kHz, to the detection electrodes 105 and 106 (capacitance C105 and C106) with a phase difference of 180 degrees from each other. To do. The vibrating body 102 is connected to the I / V converter 2.

  The inverter 8 inverts the polarity of the drive voltage Vd supplied from the drive signal generator 7 to the electrostatic capacitance C103 (shifts the phase by 180 degrees), and performs I / V conversion with the vibrating body 102 via the capacitor C1. To the connection point with the device 2. The capacitor C1 has substantially the same capacitance as the capacitance C103. The I / V converter 2 converts the input current into a voltage and outputs it to the BPFs 3 and 6 as a voltage signal Sv.

  The BPF 3 is a frequency of a carrier signal output from the carrier generation circuit 9 of the voltage signal Sv output from the I / V converter 2, for example, a frequency component of 100 kHz (a frequency reflecting the angular velocity applied to the vibrating body 102). Component) is selectively passed and output to the amplifier 4. The amplifier 4 amplifies the signal output from the BPF 3 and outputs the amplified signal to the synchronous detection circuit 5. The synchronous detection circuit 5 performs synchronous detection on the signal output from the amplifier 4 based on the carrier signal output from the carrier generation circuit 9 and detects the displacement amount of the vibrating body 102, that is, the angular velocity applied to the gyro sensor 101. Sout is output.

  The BPF 6 generates a frequency component of the driving voltage Vd output from the driving signal generator 7 (resonance frequency of the vibrating body 102) of the voltage signal Sv output from the I / V converter 2, for example, a frequency component of 2.3 kHz. The vibration detection signal Sd is output to the drive signal generator 7.

Next, the operation of the angular velocity detection device 1 configured as described above will be described. First, the drive signal generator 7 supplies an arbitrary frequency signal as a drive voltage Vd to the drive electrode 103 (capacitance C103). Then, the vibrating body 102 vibrates due to the electrostatic force generated between the driving electrode 103 and a current I ₁₀₃ flows from the driving signal generator 7 to the vibrating body 102 via the electrostatic capacitance C103. In this case, since the vibrator 102 changes the capacitance C103 by spacing changes between the vibration member 102 and the driving electrode 103 vibrates, the current I _103, by the capacitance C103 is changed A signal component to be superimposed, that is, a vibration component indicating mechanical displacement of the vibrating body 102 in the X-axis direction when the vibrating body 102 is vibrated, and a driving voltage component generated when the driving voltage Vd passes through the capacitance C103. And are included. In this case, the current I ₁₀₃ corresponds to the induced signal in the claims.

Next, the inverter 8 inverts the polarity of the driving voltage Vd supplied from the driving signal generator 7 to the capacitance C103 (shifts the phase by 180 degrees) by the inverter 8 via the capacitor C1. It is output to the connection point with the I / V converter 2. Then, since the capacitor C1 has substantially the same capacitance as that of the capacitance C103, the current I _C1 flowing through the capacitor C1 is substantially the same as the driving voltage component in the current I ₁₀₃ and the flowing direction is a reverse current. Is done. Accordingly, the current I _C1 , that is, the current corresponding to the drive voltage component is subtracted from the current I ₁₀₃ flowing from the vibrating body 102 to the I / V converter 2, and the current I ₂ indicating the vibration component is supplied to the I / V converter 2. Is done. As a result, the drive voltage component is subtracted from the current I _103, and the current I ₂ indicating the vibration component can be supplied to the I / V converter 2. In this case, the current I ₂ corresponds to an example of a superimposed signal.

Next, the current I ₂ is converted into a voltage by the I / V converter 2 and output to the BPFs 3 and 6 as the voltage signal Sv. Then, the BPF 6 outputs the resonance signal of the vibrating body 102 of the voltage signal Sv output from the I / V converter 2, for example, a frequency component of 2.3 kHz to the drive signal generator 7 as the vibration detection signal Sd. The detection signal Sd is shifted in phase by 90 degrees by the drive signal generator 7 and supplied to the drive electrode 103 (capacitance C103) as the drive voltage Vd, so that the vibrating body 102 vibrates at the resonance frequency.

In this case, the current I ₂ showing the vibration component drive voltage component is subtracted from the current I ₁₀₃ produced by the inverter 8 and the capacitor C1, the voltage signal Sv indicating a vibration component generated in response the current I ₂ Since the phase is shifted by 90 degrees and supplied to the driving electrode 103 (capacitance C103) as the driving voltage Vd, the vibrating body 102 can be vibrated stably at the resonance frequency.

Next, in a state where the vibrating body 102 is vibrating at the resonance frequency, a carrier signal of, for example, 100 kHz from the carrier generation circuit 9 is 180 degrees out of phase with the detection electrodes 105 and 106 (capacitances C105 and C106). Supplied. When the angular velocity is applied to the gyro sensor 101 and the position of the vibrating body 102 is displaced by the Coriolis force in the Y-axis direction, the distance between the vibrating body 102 and the detection electrodes 105 and 106 changes to change the capacitance C105. results discrepancies between the C106, difference occurs between the current I ₁₀₅ and the current I _106, detection current I ₁ corresponding to a difference between the current I ₁₀₅ and the current I ₁₀₆ is the I / V converter 2 Flowing. Accordingly, a current (I ₁ + I ₂ ) obtained by combining the detection current I ₁ and the current I ₂ is input to the I / V converter 2, and the current (I ₁ + I ₂ ) is converted into a voltage by the I / V converter 2. And output to the BPFs 3 and 6 as the voltage signal Sv.

Next, the frequency component of the carrier signal output from the carrier generating circuit 9, for example, the frequency component of 100 kHz, is passed through the voltage signal Sv output from the I / V converter 2 by the BPF 3 and output to the amplifier 4. As a result, a signal component based on the current I ₁ in the voltage signal Sv, that is, a signal component reflecting the angular velocity applied to the gyro sensor 101 is output from the BPF 3 to the amplifier 4.

  The signal reflecting the angular velocity output from the BPF 3 is amplified by the amplifier 4 and output to the synchronous detection circuit 5, and the signal output from the amplifier 4 by the synchronous detection circuit 5 is output from the carrier generation circuit 9. Is detected based on the carrier signal, and a detection signal Sout representing the displacement amount of the vibrating body 102, that is, the angular velocity applied to the gyro sensor 101 is output.

In this case, the current I ₁ based on the Coriolis force acting on the vibrating body 102 can be detected according to the angular velocity applied to the vibrating body 102 in a state where the vibrating body 102 is stably vibrated at the resonance frequency, Since the detection signal Sout representing the angular velocity is generated based on the current I ₁ , the vibration due to the resonance frequency of the vibrating body 102 can be stabilized and the angular velocity detection accuracy can be improved.

  In the gyro sensor 101, as shown in FIG. 8, the vibrating body 102, the driving electrode 103, and the detection electrodes 105 and 106 are arranged in the horizontal plane to vibrate the vibrating body 102 in the horizontal direction. As shown in FIG. 2, the driving electrode 103 may be disposed below the vibrating body 102 to vibrate the vibrating body 102 in the vertical direction (Z-axis direction). The Coriolis force F acting on the gyro sensor 101a shown in FIG. 2 when the angular velocity R is applied is expressed by the following equation (1).

F = 2mv × R (1)
Here, m is the mass of the vibrating body 102, and v is the displacement speed of the vibrating body 102.

From Equation (1), the Coriolis force F is proportional to the mass m of the vibrating body 102. Therefore, as the mass m is increased, the Coriolis force acting on the vibrating body 102 can be increased and the displacement amount of the vibrating body 102 can be increased. Therefore, the detection current I ₁ obtained according to the angular velocity R can be increased. As a result, the angular velocity detection accuracy can be improved.

On the other hand, when the driving electrode 103 is disposed below the vibrating body 102 as shown in FIG. 2, the area of the driving electrode 103 is increased and the electrostatic capacitance between the driving electrode 103 and the vibrating body 102 is increased. It becomes easy to increase the capacity C103 and increase the driving force of the vibrating body 102 by electrostatic force. Therefore, according to the configuration of the gyro sensor 101a shown in FIG. 2, the driving force of the vibrating body 102 by the driving electrode 103 is increased, and the mass of the vibrating body 102 is increased, thereby increasing the detection current I ₁ and the angular velocity. It becomes easy to improve detection accuracy.

In this case, increasing the capacitance C103, so that the drive voltage components at a current I ₁₀₃ flowing through the capacitance C103 increases. However, in the angular velocity detection device 1 shown in FIG. 1, the capacitance of the capacitor C1 is substantially the same as the capacitance C103 even when the capacitance C103 is increased using the gyro sensor 101a shown in FIG. Since the driving voltage component in the current I ₁₀₃ can be removed, the influence of the driving voltage component can be eliminated, the vibration due to the resonance frequency of the vibrating body 102 can be stabilized, and the angular velocity detection accuracy can be improved. Easy.

(Second Embodiment)
Next, an angular velocity detection device according to the second embodiment of the present invention will be described. FIG. 3 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. 3 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. 3, the amplification factor of the inverted signal in the inverter 8a is made variable. 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.

In the angular velocity detection device 1a shown in FIG. 3, similarly to the angular velocity detection device 1 shown in FIG. 1, an inverted signal obtained by inverting the polarity of the driving voltage Vd by the inverter 8a is connected to the vibrating body 102 and the I / V via the capacitor C1. By outputting to the connection point with the converter 2, the current I _C1 , that is, the current corresponding to the drive voltage component, is subtracted from the current I ₁₀₃ flowing from the vibrating body 102 to the I / V converter 2, thereby indicating the vibration component. The current I ₂ is supplied to the I / V converter 2. In this case, in order to subtract the current corresponding to the drive voltage component from the current I ₁₀₃ , it is desirable that the capacitance of the capacitor C1 and the capacitance C103 be substantially the same.

However, since the capacitance C103 is affected by the distance between the vibrating body 102 and the drive electrode 103, the area of the drive electrode 103, and the like, the capacitance C103 is likely to vary due to the processing accuracy of the gyro sensor 101. Therefore, when the capacitance of the capacitor C1 is smaller than the capacitance C103, the amplification factor of the inverter 8a is increased. When the capacitance of the capacitor C1 is larger than the capacitance C103, the amplification factor of the inverter 8a. , The accuracy of subtracting the current corresponding to the drive voltage component from the current I ₁₀₃ is improved even when a difference occurs between the capacitance of the capacitor C1 and the capacitance C103. The influence of the component can be eliminated to stabilize the vibration due to the resonance frequency of the vibrating body 102, and the angular velocity detection accuracy can be improved.

  The amplification factor of the inverter 8a may be set so that, for example, when a predetermined angular velocity is given to the gyro sensor 101, a detection signal Sout indicating the angular velocity is obtained.

  FIG. 4 is a circuit diagram showing an example of the configuration of the inverter 8a shown in FIG. The inverter 8a shown in FIG. 4 is a so-called inverting amplifier circuit, the non-inverting input terminal of the operational amplifier 81 is connected to the ground, and the driving voltage Vd is input to the inverting input terminal of the operational amplifier 81 via the resistor R1. A variable resistor VR1 is used as a feedback resistor. According to the inverter 8a shown in FIG. 4, the gain of the inverted signal can be made variable by setting the resistance value of the variable resistor VR1.

(Third embodiment)
Next, an angular velocity detection device according to the third embodiment of the present invention will be described. FIG. 5 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. 5 is different from the angular velocity detection device 1a shown in FIG. 3 in the following points. That is, the angular velocity detection device 1b shown in FIG. 5 includes an auto gain controller (hereinafter referred to as AGC) 8b (inverted signal output unit) in which the gain of the inverted signal is made variable instead of the inverter 8a. Further provided is an amplification factor setting unit 11 for setting the amplification factor.

The amplification factor setting unit 11 sets the amplification factor in the AGC 8b so as to minimize the level of the vibration detection signal Sd output from the BPF 6, that is, the current I ₂ generated by the capacitor C1. Further, when setting the amplification factor in the AGC 8b, the amplification factor setting unit 11 uses the BPF 6 to set the frequency of the driving voltage Vd supplied from the driving signal generator 7 to a frequency different from the resonance frequency of the vibrator 102. The signal path of the vibration detection signal Sd supplied to the drive signal generator 7 is blocked.

  Since the other configuration is the same as that of the angular velocity detection device 1a shown in FIG. 3, the description thereof will be omitted, and the characteristic points of the present embodiment will be described below. The amplification factor setting unit 11 illustrated in FIG. 5 includes a full-wave rectifier circuit 12, a capacitor C2, a comparison unit 13, a mode switching unit 14, and a switch SW1. The full-wave rectifier circuit 12 is a full-wave rectifier circuit that full-wave rectifies the vibration detection signal Sd output from the BPF 6. Capacitor C2 smoothes the signal output from full-wave rectifier circuit 12 to generate signal Sa. The amplification factor setting unit 11 may be configured using, for example, a microcomputer, and is not limited to the configuration of the amplification factor setting unit 11 shown in FIG.

  The mode switching unit 14 is a control circuit for switching between a setting mode for setting the amplification factor in the AGC 8b and a measurement mode for measuring the angular velocity, and outputs a control signal to control the operation of the comparison unit 13. Switch. When the control signal instructing the setting mode is output from the mode switching unit 14, the comparison unit 13 compares the signal level of the signal Sa with a predetermined reference level Vref1, and amplifies the signal according to the comparison result. A control signal is output to the AGC 8b to change the rate, and a mode signal Sb is output to the switch SW1 at a low level to turn off the switch SW1. Further, when the control signal instructing the measurement mode is output from the mode switching unit 14, the comparison unit 13 holds the amplification factor of the AGC 8b and sets the mode signal Sb to a high level to turn on the switch SW1. The mode signal Sb is a signal that is set to a low level in the setting mode and set to a high level in the measurement mode.

  The switch SW1 is interposed between the BPF 6 and the drive signal generator 7, and the signal path of the vibration detection signal Sd supplied from the BPF 6 to the drive signal generator 7 depends on the mode signal Sb from the comparison unit 13. Open and close. The AGC 8b changes the signal amplification factor according to the control signal from the comparison unit 13.

Since the other configuration is the same as that of the angular velocity detection device 1a shown in FIG. 3, the description thereof will be omitted, and the operation of the angular velocity detection device 1b shown in FIG. 5 will be described below. First, for example, when an operation power supply voltage is supplied to each part of the angular velocity detection device 1b by turning on a power switch (not shown), for example, the control signal is sent to the comparison unit 13 by the mode switching unit 14 to switch to the setting mode. The mode signal Sb from the comparison unit 13 is set to the low level and the switch SW1 is turned off. Then, when the signal path of the vibration detection signal Sd supplied from the BPF 6 to the drive signal generator 7 is blocked, a signal obtained by shifting the phase of the vibration detection signal Sd by 90 degrees by the drive signal generator 7 is used as the drive voltage Vd. since it is supplied to the driving electrodes 103 is eliminated, the voltage Vd for driving the frequency different from the resonance frequency f ₀ of the vibrator 102 from the drive signal generator 7 to the driving electrode 103 is supplied, the resonance frequency f ₀ The vibrating body 102 vibrates at different frequencies.

Next, when the vibrating body 102 vibrates at a frequency different from the resonance frequency f ₀ , the amount of displacement of the vibrating body 102 decreases, so that vibration in the current I ₁₀₃ flowing from the vibrating body 102 to the I / V converter 2 occurs. Ingredients decrease. In this case, it is desirable that the drive signal generator 7 outputs a signal having a frequency at which the vibration component in the current I ₁₀₃ becomes substantially zero as the drive voltage Vd. Then, if the vibration component in the current I ₁₀₃ is substantially zero, the current I ₁₀₃ is That corresponds to the driving voltage component, by setting the amplification factor of AGC8b to the current I ₁₀₃ to minimum, the current I ₁₀₃ The accuracy of subtracting the current corresponding to the drive voltage component can be improved.

Therefore, the amplification factor setting unit 11 sets the amplification factor of the AGC 8 b so as to minimize the vibration detection signal Sd obtained by the I / V converter 2 and the BPF 6 based on the current I ₁₀₃ . FIG. 6 is a signal waveform diagram for explaining the operation of the amplification factor setting unit 11. First, at timing T1 in FIG. 6, it is supplied driving voltage Vd at a frequency different from the resonance frequency f ₀ from the drive signal generator 7 in the setting mode to the driving electrodes 103 (capacitance C103), the vibrator 102 A current I ₁₀₃ having substantially zero vibration component is output. In this state, since the amplification factor of the AGC 8b is not set, even if the signal Sc obtained by inverting and amplifying the driving voltage Vd from the AGC 8b is supplied to the capacitor C1, the current I ₁₀₃ cannot be sufficiently canceled. Therefore, the signal level of the vibration detection signal Sd generated by the I / V converter 2 and the BPF 6 based on the current I ₂ obtained by subtracting the current I _C1 from the current I ₁₀₃ is high.

Next, the vibration detection signal Sd is full-wave rectified by the full-wave rectification circuit 12, smoothed by the capacitor C2, and the effective value voltage of the vibration detection signal Sd is input to the comparison unit 13 as the signal Sa. Then, the comparator 13 determines that the level of the signal Sa is higher than the reference level Vref1, increases the amplification factor of the AGC 8b, increases the signal level of the signal Sc output from the AGC 8b, and increases the current I _C1 . The current I ₂ decreases and the level of the vibration detection signal Sd decreases. As described above, by repeating the comparison process of the vibration detection signal Sd and the amplification factor setting process of the AGC 8b by the comparison unit 13, the level of the vibration detection signal Sd is gradually decreased and the signal level of the signal Sa is also decreased. .

Next, when the signal level of the signal Sa decreases and becomes equal to or lower than the reference level Vref1, the current I ₁₀₃ is sufficiently canceled by the comparator 13 by the signal Sc output from the AGC 8b, and the amplification factor of the AGC 8b is set to an appropriate value. Therefore, the control unit 13 outputs a control signal indicating that the gain of the AGC 8b is maintained, the mode signal Sb is set to high level, the switch SW1 is turned on, and the measurement mode is entered.

  In the measurement mode, the amplification factor of the AGC 8b is maintained at the amplification factor set in the setting mode. Thereafter, the angular velocity is detected by the same operation as that of the angular velocity detection device 1a shown in FIG. 3, and a detection signal indicating the detected angular velocity. Sout is output.

As a result, even when the characteristics of internal circuits such as the gyro sensor 101 and the AGC 8b change due to environmental changes such as temperature changes and aging deterioration, the drive voltage component cannot be sufficiently removed from the current I ₁₀₃ , so that the amplification factor can be set. Since the amplification factor of the AGC 8b is set by the unit 11 so as to sufficiently remove the drive voltage component, the accuracy of subtracting the current corresponding to the drive voltage component from the current I ₁₀₃ is improved, and the influence of the drive voltage component is eliminated and the vibrator The vibration due to the resonance frequency 102 can be stabilized, and the detection accuracy of the angular velocity can be improved.

  For example, the mode switching unit 14 may include an operation switch that receives a setting mode instruction from the user, and may switch to the setting mode when the setting mode instruction is received. Further, the mode switching unit 14 is configured such that the level of the signal Sa exceeds the reference level Vref1 by the comparison unit 13 in a certain period after the angular velocity detection device 1b is activated in a state where no angular velocity is applied to the gyro sensor 101, for example. It is good also as a structure which switches to setting mode when this is detected. Alternatively, the mode switching unit 14 may have a timer function and switch from the measurement mode to the setting mode at regular intervals.

(Fourth embodiment)
Next, an angular velocity detection device according to the fourth embodiment of the present invention will be described. FIG. 7 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. 7 differs from the angular velocity detection device 1b shown in FIG. 5 in the following points. That is, the angular velocity detection device 1c shown in FIG. 7 further includes an AGC 15 that amplifies the vibration detection signal Sd output from the BPF 6 and outputs the amplified vibration detection signal Sd2 to the full-wave rectifier circuit 12 and the switch SW1. The AGC 15 is an amplifier circuit that changes the amplification factor of the vibration detection signal Sd according to the mode signal Sb output from the comparison unit 13, and when the mode signal Sb becomes high level, that is, the amplification factor of the AGC 8b is set in the setting mode. When the measurement mode is set after the setting, the amplification factor of the vibration detection signal Sd is increased to such an extent that the signal level of the vibration detection signal Sd2 is not saturated.

  Since the other configuration is the same as that of the angular velocity detection device 1b shown in FIG. 5, the description thereof will be omitted, and the operation of the present embodiment will be described below. First, in the measurement mode, since the vibration detection signal Sd indicating the vibration component output from the BPF 6 is a very small signal, the drive signal generator 7 uses the vibration detection signal Sd having a small signal amplitude as it is, and the phase is 90 degrees. When the signal processing to be shifted is performed, the accuracy of the phase shift in the driving voltage Vd is lowered, and the stability of the resonance vibration of the vibrating body 102 is impaired. Therefore, in the measurement mode, it is desirable to increase the amplification factor of the AGC 15 and sufficiently increase the signal amplitude of the vibration detection signal Sd2 within a range that does not saturate, and then perform signal processing such as phase shift in the drive signal generator 7.

Therefore, first, similarly to the angular velocity detection device 1b shown in FIG. 5, for example, when the user turns on a power switch (not shown) to supply the operation power supply voltage to each unit of the angular velocity detection device 1c, the mode switching unit 14, a control signal is output to the comparison unit 13 to switch to the setting mode, and the mode signal Sb is set to a low level by the comparison unit 13 and the switch SW1 is turned off. Then, a driving voltage Vd is supplied from the driving signal generator 7 to the driving electrode 103 (capacitance C103) at a frequency different from the resonance frequency f _0, and a current I ₁₀₃ having substantially zero vibration component is generated from the vibrating body 102. Is output. In this state, since the amplification factor of the AGC 8b is not set, even if the signal Sc obtained by inverting and amplifying the driving voltage Vd from the AGC 8b is supplied to the capacitor C1, the current I ₁₀₃ cannot be sufficiently canceled. Therefore, the level of the vibration detection signal Sd that is voltage-converted by the I / V converter 2 based on the current I ₁₀₃ and filtered by the BPF 6 is high.

  On the other hand, when the mode signal Sb is set to the low level by the comparison unit 13 and the setting mode is set, the AGC 15 amplifies the vibration detection signal Sd with a predetermined amplification factor α set in advance, and the full-wave rectifier circuit 12 is used as the vibration detection signal Sd2. And output to the switch SW1. In this case, as described above, since the level of the vibration detection signal Sd is high when the amplification factor of the AGC 8b is not set, the amplification factor α is, for example, not to saturate the vibration detection signal Sd2. Low amplification factor.

  Next, when the amplification factor of the AGC 8b is set by the amplification factor setting unit 11 in the same manner as the angular velocity detection device 1b shown in FIG. 5, the drive voltage component is removed from the vibration detection signal Sd and the signal level is lowered. Therefore, after the amplification factor of the AGC 8b is set by the amplification factor setting unit 11, the mode signal Sb is set to the high level by the comparison unit 13, that is, when the measurement mode is set, the phase of the drive signal generator 7 is shifted by 90 degrees. In order to improve the accuracy of the signal processing to be performed, the amplification factor of the AGC 15 is increased, and the signal amplitude of the vibration detection signal Sd2 is increased. In this case, the amplification factor of the AGC 15 is set so as to be the maximum amplification factor in a range where the vibration detection signal Sd2 is not saturated, for example.

  Thereby, in the measurement mode, it is possible to increase the signal amplitude of the vibration detection signal Sd2 and improve the accuracy of signal processing for shifting the phase by 90 degrees in the drive signal generator 7. Therefore, the phase shift of the drive voltage Vd can be improved. By improving the accuracy and improving the stability of the vibrating body 102 in the resonance vibration, the detection accuracy of the angular velocity can be improved.

  The inventor of the present application can experimentally increase the amplification factor of AGC 8b in the measurement mode by 100 times the amplification factor of AGC 8b in the setting mode by the angular velocity detection device 1c shown in FIG. It was confirmed that the accuracy of making the driving voltage Vd coincide with the resonance frequency and the stability of the vibrating body 102 in the resonance vibration is improved.

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. It is a conceptual diagram which shows the modification of the gyro sensor shown in FIG. 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. It is a circuit diagram which shows an example of a structure of the inverter shown in FIG. 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. FIG. 6 is a signal waveform diagram for explaining the operation of the amplification factor setting unit shown in FIG. 5. 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 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 a signal waveform diagram explaining the vibration detection signal detected in the angular velocity detection apparatus shown in FIG. It is a figure which shows the frequency characteristic of the vibration component signal shown in FIG. It is a figure which shows the frequency characteristic of the drive voltage component signal shown in FIG.

Explanation of symbols

1, 1a, 1b, 1c Angular velocity detector 2 I / V converter 3, 6 BPF
4 Amplifier 5 Synchronous detection circuit 7 Drive signal generator 8, 8a Inverter 9 Carrier generation circuit 11 Amplification factor setting unit 12 Full wave rectifier circuit 13 Comparison unit 14 Mode switching unit 81 Operational amplifier 101, 101a Gyro sensor 102 Vibrating body 103 Drive Electrodes 105, 106 Detection electrodes C1, C2 Capacitors C103, C105, C106 Capacitance SW1 Switch VR1 Variable resistor

Claims (6)

An angular velocity detection device,
Electrodes,
A vibrating body disposed opposite to the electrode ,
The angular velocity detection device detects the angular velocity based on Coriolis force acting on the vibrating body when an angular velocity is applied to the vibrating body;
A capacitance formed by the electrode and the vibrator;
A drive signal generator that vibrates the vibrator by supplying a drive voltage to the electrodes;
An inversion signal output unit that outputs an inversion voltage having a polarity opposite to that of the driving voltage by supplying a driving voltage from the driving signal generation unit ;
A reverse voltage output from the reverse signal output unit is supplied, and a capacitor having substantially the same capacitance as the capacitance;
A vibration component that is a current that flows from the drive signal generator to the vibrating body via the capacitance, and is a signal component that indicates a mechanical displacement of the vibrating body when the vibrating body is vibrated, and a driving voltage A current-voltage conversion unit that converts a superimposed current obtained by adding a current output via the capacitor to a current including a driving voltage component that is a signal component generated by passing through the capacitance into a superimposed voltage And comprising
The angular velocity detection device, wherein the drive signal generation unit supplies a signal obtained by shifting the phase of the vibration component of the superimposed voltage output from the current-voltage conversion unit by 90 degrees to the electrode as a drive voltage . The angular velocity detection device according to claim 1 , wherein the inversion signal output unit has an inversion voltage gain variable . An angular velocity detection device,
Electrodes,
A vibrating body disposed opposite to the electrode,
The angular velocity detection device detects the angular velocity based on Coriolis force acting on the vibrating body when an angular velocity is applied to the vibrating body;
A capacitance formed by the electrode and the vibrator;
A drive signal generator that vibrates the vibrator by supplying a drive voltage to the electrodes;
An inversion signal output unit that outputs an inversion voltage having a polarity opposite to that of the driving voltage by supplying a driving voltage from the driving signal generation unit;
A capacitor to which the inverted voltage output from the inverted signal output unit is supplied;
A vibration component that is a current that flows from the drive signal generator to the vibrating body via the capacitance, and is a signal component that indicates a mechanical displacement of the vibrating body when the vibrating body is vibrated, and a driving voltage A current-voltage conversion unit that converts a superimposed current obtained by adding a current output via the capacitor to a current including a driving voltage component that is a signal component generated by passing through the capacitance into a superimposed voltage And comprising
The drive signal generation unit supplies a signal obtained by shifting the phase of the vibration component of the superimposed voltage output from the current-voltage conversion unit by 90 degrees to the electrode as a drive voltage,
In the angular velocity detection device, the inversion signal output unit has a variable inversion voltage gain. An amplification factor setting unit for setting the amplification factor in the inverted signal output unit;
The amplification factor setting unit performs a setting operation for setting the amplification factor in the inverted signal output unit so as to minimize the level of the vibration component of the superimposed voltage output from the current-voltage conversion unit. 2. The angular velocity detection device according to 2 or 3 . The amplification factor setting unit, when performing the setting operation, makes the frequency of the driving voltage supplied by the driving signal generation unit different from the resonance frequency of the vibrating body. Angular velocity detection device. A superimposed signal amplification unit that amplifies the vibration component of the superimposed voltage output from the current-voltage conversion unit and supplies the amplified component to the drive signal generation unit;
The drive signal generation unit supplies a signal obtained by shifting the phase of the voltage amplified by the superimposed signal amplification unit by 90 degrees to the electrode as a drive voltage ,
6. The angular velocity detection according to claim 4, wherein the superimposed signal amplification unit increases an amplification factor for amplifying a vibration component of the superimposed voltage after the setting operation is performed by the amplification factor setting unit. apparatus.

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