JP2006010408A - Vibratory gyro - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibratory gyro which has raised power source dependence precision of detection sensitivity of detected signals with respect to the variations of a source voltage. <P>SOLUTION: The gyro is provided with a source voltage dependence circuit 66 which keeps the amplitude of each driving signal to be applied to a vibrator 1 and the amplitude of each detected signal obtained by detecting means 161-164 constant, by making each independent of the variations of the source voltage, and generates a power source dependent correction voltage proportional to the source voltage, and a multiplication circuit 65 for multiplying the power source dependent correction voltage generated in this circuit 66 by each detected signal outputted from signal processing circuits 31-64. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vibration gyro used for detecting angular velocity, for example.

  In recent years, vibratory gyros have been used to detect the magnitude and direction of angular velocity for vehicle attitude detection, navigation device direction detection, camera shake correction, virtual reality operation, and the like. In such a vibration gyro, in order to calculate the magnitude and direction of the actual angular velocity, an analog detection signal output from an angular velocity sensor such as a vibrator is usually converted into a digital signal by an A / D converter. Then, arithmetic processing is performed based on the digital data.

  Thus, when digitizing the analog detection signal obtained by the angular velocity sensor, for example, in a voltage comparison type A / D converter, the conversion reference voltage may depend on the power supply voltage. In order to accurately detect the magnitude and direction of the angular velocity based on the detection signal, the output reference voltage (output voltage at rest) and the angular velocity detection sensitivity of the angular velocity sensor are required to depend on the power supply voltage. .

  Therefore, conventionally, the amplitude of the drive signal applied to the angular velocity sensor is changed depending on the power supply voltage, and the output level (= detection signal amplitude) of the detection signal output from the angular velocity sensor is thereby changed according to the power supply voltage. As a result, a technique has been proposed in which the angular velocity detection sensitivity of the angular velocity sensor depends on the power supply voltage as a result (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-44540

  However, in the conventional technique as described in Patent Document 1 described above, the electrical signal is output after a drive signal that depends on the power supply voltage is applied to the angular velocity sensor until a required detection signal is output by the angular velocity sensor. → Machine, machine → electricity conversion processes are involved several times, so that conversion errors accumulate and the accuracy of the angular velocity detection signal depends on the power source.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vibrating gyroscope having improved power supply dependency accuracy of an angular velocity detection signal with respect to fluctuations in power supply voltage.

  In order to achieve the above object, the present invention provides a vibrator, drive means for driving the vibrator, detection means for detecting vibration displacement of the vibrator during application of angular velocity, and detection output of the detection means. A vibration gyro provided with a signal processing circuit that converts a signal into a detection signal having a DC voltage level corresponding to the angular velocity has the following configuration.

  In other words, the vibrating gyroscope according to the first aspect of the present invention is configured such that the amplitude of the drive signal applied to the drive unit and the amplitude of the detection signal obtained by the detection unit are not dependent on fluctuations in the power supply voltage. A power supply voltage dependent circuit for generating a power supply dependent correction voltage proportional to the power supply voltage, and the power supply dependent correction voltage generated by the power supply voltage dependent circuit in the signal processing circuit. And a multiplication circuit that multiplies the detection signal output from.

  According to a second aspect of the present invention, in the vibration gyro according to the first aspect of the present invention, the drive means electrostatically drives the vibrator, and the detection means is the vibrator of the vibrator. It is characterized by detecting vibration displacement as a change in capacitance.

  A vibrating gyroscope according to a third aspect of the invention is characterized in that, in the configuration of the first or second aspect of the invention, the multiplication circuit is constituted by a gain control amplifier.

  According to the first aspect of the present invention, the power supply dependency correction voltage generated by the power supply voltage dependent circuit is multiplied by the angular velocity detection signal amplitude by the multiplication circuit provided in the signal processing circuit. The detection sensitivity becomes dependent on the power supply voltage. In addition, when the drive signal amplitude is made dependent on the power supply voltage as in the past, the change in the voltage level of the detection signal has a linear relationship with the change in the power supply voltage because electrical / mechanical conversion is involved in the middle. In contrast, in the present invention, since the electromechanical conversion does not intervene in the middle, the change in the voltage level of the detection signal amplitude linearly corresponds to the change in the power supply voltage. Therefore, it is possible to further improve the sensitivity power supply dependence accuracy of the angular velocity detection signal with respect to the fluctuation of the power supply voltage.

  According to the second aspect of the present invention, it can be suitably used for a vibration gyro using an electrostatic drive / capacitance detection type vibrator as an angular velocity sensor.

  According to the third aspect of the present invention, since the multiplication circuit is configured by the gain control amplifier, the power supply dependency correction voltage generated by the power supply voltage dependency circuit with a simple configuration can be converted into the final value in the signal processing circuit. The detection signal output from the stage can be multiplied.

  FIG. 1 is a plan view showing a structure of a vibrator used in the vibration gyro according to this embodiment, and FIG. 2 is a cross-sectional view showing a part of a state in which the vibrator substrate and the protective substrate constituting the gyro apparatus are joined. It is.

  The vibration gyro according to this embodiment includes a vibrator 1 as an angular velocity sensor. The vibrator 1 is of an electrostatic drive / capacitance detection type and is of a non-resonance type in which the drive vibration direction resonance frequency and the detection vibration direction resonance frequency are different, and has a low resistance such as a single crystal or polycrystal. A vibrator substrate 2 made of a silicon material and a protective substrate 3 made of, for example, a high-resistance silicon material or glass material provided on the main surface and the back surface of the vibrator substrate 2 are provided. The two substrates 2 and 3 are integrally bonded by a bonding method such as anodic bonding, for example, except for the portion where the cavity 4 is formed for securing the movable part of the vibrator substrate 2. The cavity 4 is kept in a vacuum state or a low pressure state in order to reduce vibration damping.

  The vibrator substrate 2 is subjected to fine processing such as an etching process, whereby the first to fourth mass portions 71 to 74, the driving beam 8, the first and second monitor electrodes 91 and 92, and the first to first masses. Four drive electrodes 101 to 104, first to fourth detection electrodes 161 to 164, ground electrodes 181 and 182 and the like are formed. Here, in FIG. 1, when the longitudinal direction of the vibrator 1 is the Y-axis direction, the transverse direction perpendicular to the X-axis direction is the X-axis direction, and the direction perpendicular to the paper surface perpendicular to both axes is the Z-axis direction, The first to fourth mass portions 71 to 74 are supported in series along the Y-axis direction by the driving beam 8 partially connected to the ground electrodes 181 and 182, thereby the first to fourth masses. Each mass part 71-74 is in the state which can vibrate along an X-axis direction. That is, the first to fourth mass parts 71 to 74 and the drive beam 8 are movable parts, and the first and second monitor electrodes 91 and 92, the first to fourth drive electrodes 101 to 104, and the ground. Electrodes 181 and 182 are fixed portions.

  The first mass portion 71 is a comb-like movable side electrode 111a that protrudes left and right so as to oppose the comb-like portions of the first monitor electrode 91 and the first and second drive electrodes 101 and 102. , 111b, 111c are provided.

  Further, the second mass portion 72 is a first detection having a shape in which a rectangular first drive frame 121 supported by the drive beam 8 and two rectangles supported by the upper and lower first detection beams 131 are connected to each other inside the first drive frame 121. Frame 141. Comb-like movable-side electrodes 151a and 151b are formed on the outer side of the first drive frame 121 in the vicinity of the first mass portion 71 and facing the comb-like portions of the first and second drive electrodes 101 and 102. Has been. In addition, comb-shaped movable side electrodes 171 are formed on the inner sides of the two quadrangular portions of the first detection frame 141 so as to face the first and second detection electrodes 161 and 162, respectively. As a result, the first detection frame 141 can be vibrated along the Y-axis direction by the first detection beam 131 together with the movable electrode 171.

  The fourth mass portion 74 is a comb-like movable side electrode 112a that protrudes left and right so as to face the comb-like portions of the second monitor electrode 92 and the third and fourth drive electrodes 103 and 104. , 112b, 112c are provided.

  In addition, the third mass portion 73 is a second detection having a shape in which a rectangular second drive frame 122 supported by the drive beam 8 and two rectangles supported by the upper and lower second detection beams 132 are connected to each other inside the second drive frame 122. Frame 142. Comb-like movable side electrodes 152a and 152b are formed on the outer side of the second drive frame 122 in proximity to the fourth mass portion 74 and facing the comb-like portions of the third and fourth drive electrodes 103 and 104. Has been. Further, comb-shaped movable side electrodes 172 are formed on the inner side of the quadrangular portion of the second detection frame 142 so as to face the comb-shaped third and fourth detection electrodes 163 and 164, respectively. As a result, the second detection frame 142 can be vibrated along the Y-axis direction by the second detection beam 132 together with the movable electrode 172.

  The first and second monitor electrodes 91 and 92, the first to fourth drive electrodes 101 to 104, the first to fourth detection electrodes 161 to 164, and the ground electrodes 181 and 182 are protected on the transducer substrate 2. It is formed on the junction with the substrate 3 and is in a fixed state. The electrodes 91, 92, 101 to 104, 161 to 164, 181 and 182 on the fixed side are individually connected to the electrode pads 5 as shown in FIG. 5 can be electrically connected to an external electric circuit, which will be described later. The movable portion of the vibrator 1 is mechanically and electrically connected to the ground electrodes 181 and 182 via the drive beam 8 and is kept at the ground potential.

  The first and second monitor electrodes 91 and 92 and the first to fourth drive electrodes 101 to 104 are included in the drive means of the claims, and the first to fourth detection electrodes 161 to 161 are included. 164 is included in the detection means of the claims.

  FIG. 3 is a block diagram showing the overall circuit configuration of the gyro apparatus. Note that, as will be described in detail later, in the figure, the portion of the circuit block that prevents the operation reference voltage from depending on the power supply voltage Vcc is doubled to distinguish it from other circuit blocks.

  The first monitor electrode 91 is connected to the first CV conversion circuit 31, and the second monitor electrode 92 is connected to the second CV conversion circuit 32. The first and second CV conversion circuits 31 and 32 are both connected to the first differential amplifier circuit 41 via coupling capacitors C1 and C2. The first differential amplifier circuit 41 is connected to the first phase adjustment circuit 23 via the filter circuit 51. The first differential amplifier circuit 41 is also connected to a second phase adjustment circuit 60 described later via the filter circuit 51. The output portion of the first phase adjustment circuit 23 is connected to the AGC circuit 22 and the rectifier circuit 24 via a coupling capacitor C0. Further, the output part of the AGC circuit 22 is directly connected to the second drive electrode 102 and the third drive electrode 103, and is connected to the first drive electrode 101 and the fourth drive electrode 104 via the inverting circuit 21. Yes.

  The AGC circuit 22 amplifies the output signal from the first phase adjustment circuit 23 and outputs it as a drive signal S1. The output obtained by rectifying the output of the first phase adjustment circuit 23 by the rectifier circuit 24 and the reference voltage The amplification factor is controlled so that the amplitude of the input signal to the AGC circuit 22 is always constant by the output of the comparator 26 that compares the reference voltage supplied from the generation circuit 25. Note that the reference voltage output from the reference voltage generating circuit 25 is always constant without depending on the power supply voltage Vcc.

  Then, coupling capacitors C1 and C2 are interposed between the first and second CV conversion circuits 31 and 32 and the first differential amplifier circuit 41, respectively, and both the first and second CV conversion circuits 31 and 32 are fixed. By operating by receiving power supply from a voltage generation circuit (not shown), the amplitudes of the monitor signals S21 and S22 output from the first and second CV conversion circuits 31 and 32 are caused by fluctuations in the power supply voltage. I try not to depend on it.

  Thus, the coupling capacitor C0 is interposed between the first phase adjustment circuit 23 and the AGC circuit 22, and the inverting circuit 21, the AGC circuit 22, the rectifier circuit 24, and the comparator 26 are all constant voltage generating circuits (FIG. The drive signals S11 and S12 applied to the first to fourth drive electrodes 101 to 104 of the vibrator 1 do not depend on the fluctuation of the power supply voltage Vcc. I have to. That is, the amplitudes of the drive signals S11 and S12 may change due to factors other than the power supply voltage, but at least fluctuations in the power supply voltage Vcc are excluded.

  On the other hand, both the first detection electrode 161 and the third detection electrode 163 are connected to the third CV conversion circuit 33, and both the second detection electrode 162 and the fourth detection electrode 164 are connected to the fourth CV conversion circuit 34. The third and fourth CV conversion circuits 33 and 34 are both connected to the second differential amplifier circuit 42 via coupling capacitors C3 and C4.

  Thus, the coupling capacitors C3 and C4 are interposed between the third and fourth CV conversion circuits 33 and 34 and the second differential amplifier circuit 42, respectively, and the third and fourth CV conversion circuits 33 and 34 are provided. Both are operated by receiving power supply from a constant voltage generation circuit (not shown), so that the amplitudes of the detection signals S31 and S32 output from the third and fourth CV conversion circuits 33 and 34 are equal to the power supply voltage. It is not dependent on fluctuations.

Here, as the first to fourth CV conversion circuits 31 to 34, for example, a charge amplification circuit as shown in FIG. 4A or an impedance conversion circuit as shown in FIG. 4B is applied. Is done. Now, when the first to fourth CV conversion circuits 31 to 34 are constituted by, for example, charge amplification circuits as shown in FIG. 4A, each of the first to fourth detection electrodes 161 to 164 is provided. When the capacitance change ΔC is converted into a voltage change ΔV0 corresponding to this, the following relationship is established.
ΔV0 = ω · ΔC · Vref · Rf (1)
Here, ω is an angular frequency when the vibrator 1 is excited, Vref is a reference voltage, and Rf is a feedback impedance of the operational amplifier Amp1.

  As can be seen from the equation (1), the voltage change (that is, detection sensitivity) ΔV 0 changes not only by the capacitance change ΔC but also by the reference voltage Vref. In this embodiment, in order to remove the variation factor, the reference voltage Vref is maintained at a constant voltage so as not to depend on the power supply voltage Vcc.

Further, when the first to fourth CV conversion circuits 31 to 34 are configured by impedance conversion circuits as shown in FIG. 4B, for example, each of the first to fourth detection electrodes 161 to 164 is provided. When the capacitance change ΔC is converted into a voltage change ΔV0 corresponding to this, the following relationship is established.
ΔV0 = ΔC / (C + ΔC) · Vref (where R >> 1 / (ωC)) (2)
Here, C is the capacitance of each of the first to fourth detection electrodes 161 to 164, and Vref is a reference voltage.

  As can be seen from the equation (2), the voltage change (that is, detection sensitivity) ΔV 0 changes not only by the capacitance change ΔC but also by the reference voltage Vref. The constant voltage is maintained so as not to depend on the voltage Vcc.

  The output section of the second differential amplifier circuit 42 is connected to the synchronous detection circuit 61 via the filter circuit 52. Further, the second phase adjusting circuit 60 described above outputs the detection reference signal S4 by shifting the phase of the output signal S2 'of the filter circuit 51 by 90 °. The filter circuit 51 and the filter circuit 52 are designed in advance so that their phase rotation amounts are the same.

  The synchronous detection circuit 61 performs phase detection of the angular velocity detection signal S3 provided from the second differential amplifier circuit 42 via the filter circuit 52 in synchronization with the detection reference signal S4 output from the second phase adjustment circuit 60. It is. The synchronous detection circuit 61 is connected to a temperature compensation circuit 64 via a smoothing circuit 62 and an amplifier circuit 63. The temperature compensation circuit 64 is for removing the influence of temperature drift or the like that occurs in the vibrator 1 and its peripheral circuits.

  A multiplier circuit 65 is connected to the temperature compensation circuit 64. The multiplication circuit 65 is connected to a power supply voltage dependency circuit 66 that generates a power supply dependency correction voltage Ve proportional to the power supply voltage Vcc. In this example, the power supply voltage dependency circuit 66 is constituted by a voltage dividing circuit that divides the power supply voltage Vcc by connecting two resistors R1 and R2 in series. The multiplication circuit 65 multiplies the power supply dependency correction voltage Ve generated by the power supply voltage dependency circuit 66 by the amplitude of the detection signal S7 output from the temperature compensation circuit 64 which is the final stage of the signal processing circuit. Here, it is constituted by a gain control amplifier.

  As described above, each circuit 21, 22, 24-26, 31-34 surrounded by the double block in FIG. 3 always has a stable constant voltage without being affected by fluctuations in the power supply voltage Vcc. It operates by receiving power supply from a constant voltage generation circuit (not shown). On the other hand, the circuits 23, 41, 42, 51, 52, and 60 in other blocks are portions that do not affect the operation even if the operation reference voltage depends on the power supply voltage Vcc. Since the circuits 61 to 65 make the sensor output reference voltage dependent on the power supply, the circuit operation reference voltage depends on the power supply voltage Vcc. Each of the circuits 33, 34, C3, C4, 42, 52, 60 to 64 corresponds to the signal processing circuit in the claims.

Next, the operation of the vibration gyro configured as described above will be described.
The first and fourth drive electrodes 101 and 104 are supplied with a drive signal S12 after the level of the drive signal S11 output from the AGC circuit 22 is inverted by the inverter circuit 21. The drive signal S11 output from the AGC circuit 22 is applied to the second and third drive electrodes 102 and 103 as they are. In this case, as shown in FIGS. 5A and 5B, the drive signals S11 and S12 are AC signals whose levels are inverted with respect to the ground potential with reference to an offset potential of, for example, + 2.5V. is there.

  For this reason, for example, when one drive signal S12 is at a high level and the other drive signal S11 is at a low level, the first and fourth drive electrodes 101, 104 and the movable-side electrodes 111a, While the electrostatic attractive force of 151a and 112b and 152b is in a “strong” state, the second and third drive electrodes 102 and 103 and the movable side electrodes 111b, 151b and 112a and 152a facing these electrodes 102 and 103 The electrostatic attractive force is in a “weak” state. Naturally, when the levels of the two signals S12 and S11 are opposite, the state described above is reversed. For this reason, due to the difference in electrostatic attraction, as shown in FIG. 6A, the first to fourth mass parts 71 to 74 are driven in the X axis direction in opposite phases and vibrate.

  Depending on this vibration, the capacitance between the movable side electrode 111c and the first monitor electrode 91 provided in the first mass part 71, and the movable side electrode 112c and the second monitor electrode provided in the fourth mass part 74 are provided. The capacity between 92 varies.

  Capacitance changes in the first and second monitor electrodes 91 and 92 that monitor the driving vibration state in the X-axis direction of the vibrator 1 have voltage levels corresponding to the respective capacitance changes by the first and second CV conversion circuits 31 and 32. Converted to monitor signals S21 and S22. In this case, since both monitor signals S21 and S22 are opposite in phase, they are amplified and converted into one monitor signal S2 by the first differential amplifier circuit 41 in the next stage.

  The monitor signal S2 is input to the AGC circuit 22 after unnecessary noise components are removed by the filter circuit 51 and the phase adjustment necessary for self-excited oscillation is performed by the first phase adjustment circuit 23. The output signal of the first phase adjustment circuit 23 is rectified by the rectifier circuit 24 and then compared with the reference voltage supplied from the reference voltage generation circuit 25 by the comparator 26, and output from the AGC circuit 22 by the output of the comparator 26. The amplification factor of the drive signal S1 is controlled. Therefore, the amplitude and offset potential of drive signal S1 are always kept constant without depending on power supply voltage Vcc. Therefore, drive signals S11 and S12 having an appropriate amplitude are always applied to the first to fourth drive electrodes 101 to 104, respectively.

  In this way, the drive signals S11 and S12 are generated from the monitor signal S2 obtained by the first and second monitor electrodes 91 and 92, respectively, and the drive signals S11 and S12 are applied to the first to fourth drive electrodes. Thus, a closed-loop self-excited oscillation circuit is configured, and the vibrator 1 continues to vibrate at the same resonance frequency as the drive signals S11 and S12.

  In this state, when a rotational angular velocity with the Z axis as the central axis is applied to the vibrator 1, a Coriolis force is generated in each mass portion 71 to 74 in the Y axis direction orthogonal to the vibration direction. Then, the first and second detection frames 141 and 142 and the movable electrodes 171 and 172 supported by the first and second detection beams 131 and 132 are, as shown in FIG. Driven in opposite directions in the axial direction, it vibrates at the same frequency as the drive vibration in the X-axis direction. Depending on this vibration, the capacitance between the movable side electrodes 171 and 172 and the first to fourth detection electrodes 161 to 164 provided in the first and second detection frames 141 and 142, respectively, changes. In addition, in FIG.6 (b), it is abbreviate | omitting about the vibration of the X-axis direction of each mass part 71-74.

The Coriolis force F generated when the angular velocity is applied is given by the following equation.
F = 2 ・ M ・ ω ・ v (3)
Here, M is the mass of the entire first to fourth mass parts 71 to 74, ω is the angular velocity, and v is the driving vibration speed of the entire first to fourth mass parts 71 to 74.

  Here, when the vibrator 1 is a non-resonant type, the structural resonance frequency of the vibrator 1 in the Y-axis direction is sufficiently separated from the vibration frequency when driven in the X-axis direction by the drive signals S11 and S12. Therefore, the vibration in the Y-axis direction caused by the Coriolis force and the drive vibration in the X-axis direction driven by the drive signals S11 and S12 have a phase difference of 90 °. For this reason, if vibration in the Y-axis direction occurs while driving and vibrating in the X-axis direction, the first to fourth mass parts 71 to 74 perform elliptical motion as shown in FIG. Therefore, the capacitance change generated in the first and second monitor electrodes 91 and 92 due to the drive vibration and the capacitance change generated in the detection electrodes 161 to 164 due to the vibration due to the Coriolis force are 90 ° in phase difference. Will occur.

  On the other hand, the capacitance change generated in the first and third detection electrodes 161 and 163 due to the vibration due to the Coriolis force is converted by the third CV conversion circuit 33 into a detection signal S31 having a voltage level corresponding to the capacitance change. Similarly, the capacitance change generated in the second and fourth detection electrodes 162 and 164 due to the vibration due to the Coriolis force is converted into a detection signal S32 having a voltage level corresponding to the capacitance change by the fourth CV conversion circuit 34.

  The detection signals S31 and S32 output from the third and fourth CV conversion circuits 33 and 34, respectively, are signals having opposite phases with respect to the components depending on the Coriolis force, and therefore are detected by the second differential amplifier circuit 42 in the next stage. Amplified and converted into two detection signals S3. This detection signal S3 is input to the synchronous detection circuit 61 after unnecessary noise components are removed by the filter circuit 52.

  The monitor signal S2 output from the first differential amplifier circuit 41 is input to the second phase adjustment circuit 60 after unnecessary noise components are removed by the filter circuit 51. The filter circuit 51 and the filter circuit 52 are designed in advance so that their phase rotation amounts are the same. Therefore, the second phase adjustment circuit 60 shifts the phase of the output signal S2 'of the filter circuit 51 by 90 degrees and outputs it as the detection reference signal S4. As described above, in the non-resonant type vibrator 1, the monitor signal S2 and the detection signal S3 are originally output with a phase difference of 90 °. Therefore, the detection reference signal S4 output from the second phase adjustment circuit 60 is in phase (or out of phase) with the Coriolis component of the signal S3 ′ output from the filter circuit 52, and this detection reference signal S4 is the synchronous detection circuit. 61 is input.

  The synchronous detection circuit 61 synchronously detects the detection signal S3 'that has passed through the filter circuit 52 by the detection reference signal S4. In this case, since both the signals S3 ′ and S4 are in phase (or in reverse phase), the detection signal S5 after being synchronously detected by the synchronous detection circuit 61 has a half-wave rectified form, which is further smoothed. The detection signal S6 having a DC voltage level corresponding to the angular velocity is obtained by being smoothed by the circuit 62. The detection signal S6 is amplified by the amplification circuit 63 at the next stage and then supplied to the temperature compensation circuit 64. The temperature compensation circuit 64 outputs a detection signal S7 excluding the influence of temperature drift and the like generated in the vibrator 1 and its peripheral circuits. Then, the detection signal S7 is given to the next-stage multiplication circuit 65.

  The circuit operation reference voltage of the synchronous detection circuit 61 to the multiplication circuit 65 depends on the power supply voltage Vcc, and the reference voltage (output voltage at rest) of the angular velocity output voltage is proportional to the power supply voltage Vcc. Further, the multiplication circuit 65 uses the power supply dependency correction voltage Ve generated by the power supply voltage dependency circuit 66 as the amplitude (corresponding to the angular velocity) of the detection signal S7 output from the temperature compensation circuit 64 which is the final stage of the signal processing circuit. (Voltage change in minutes). In this case, since the power supply dependency correction voltage Ve has a value proportional to the power supply voltage Vcc, the amplitude of the detection signal S8 output from the multiplication circuit 65 also depends on the power supply voltage Vcc. Thus, only the amplification factor of the multiplication circuit 65 at the final stage of the signal processing circuit depends on the power supply voltage Vcc, and the sensitivity of the detection signal S8 is purely dependent on the power supply voltage.

  In addition, in this embodiment, since the amplitude of the drive signals S11 and S12 does not depend on the power supply voltage Vcc, no electro-mechanical conversion is involved in the middle, and therefore the sensitivity of the detection signal S8 with respect to changes in the power supply voltage Vcc. The change corresponds to linear. Therefore, it is possible to improve the sensitivity power supply dependency accuracy of the detection signal S8 with respect to the fluctuation of the power supply voltage Vcc as compared with the conventional case. Note that the multiplication circuit 65 is not necessarily provided in the final stage, and may be arranged in another place as long as it is within the signal processing circuit.

  In the above embodiment, the vibration gyro provided with the electrostatic drive / capacitance detection type vibrator 1 has been described. However, the present invention is not limited to this, for example, a sound made of a piezoelectric material or a single crystal. The present invention can also be applied to a vibration gyro provided with a single-type vibrator and a vibration gyro provided with a tuning fork vibrator.

It is a top view which shows the structure of the vibrator | oscillator of the vibration gyro in embodiment of this invention. It is sectional drawing which shows a part of the state which joined the vibrator substrate and protective substrate which comprise this gyro apparatus. It is a block diagram which shows the circuit structure of a vibration gyro. It is a circuit diagram which shows an example of a CV conversion circuit. It is a wave form diagram of the drive signal applied to the drive electrode of a vibrator. It is explanatory drawing of the vibration state of a vibrator | oscillator. It is explanatory drawing which shows the relationship between the drive vibration direction in a vibrator | oscillator, and the vibration direction by a Coriolis force.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibrators 31-34, 41, 42, 51, 52, 60-64 Signal processing circuit 65 Multiplication circuit 66 Power supply voltage dependence circuit 91, 92 Monitor electrode 101-104 Drive electrode (drive means)
161-164 Detection electrodes (detection means)
C0-C4 coupling capacitor

Claims (3)

A vibrator, a drive means for driving the vibrator, a detection means for detecting vibration displacement of the vibrator when an angular velocity is applied, and a detection output of the detection means as a detection signal having a DC voltage level corresponding to the angular velocity. In a vibration gyro provided with a signal processing circuit for conversion, the amplitude of the drive signal applied to the drive means and the amplitude of the detection signal obtained by the detection means are both constant without depending on fluctuations in the power supply voltage. And a power supply voltage dependent circuit for generating a power supply dependent correction voltage proportional to the power supply voltage,
A multiplication circuit that multiplies the detection signal output from the signal processing circuit by the power supply dependence correction voltage generated by the power supply voltage dependence circuit;
A vibrating gyroscope characterized by comprising: 2. The drive unit according to claim 1, wherein the drive unit electrostatically drives the vibrator, and the detection unit detects a vibration displacement of the vibrator as a change in capacitance. Vibration gyro. 3. The vibration gyro according to claim 1, wherein the multiplication circuit is configured by a gain control amplifier.

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