JP2007292680A - Vibration gyrosensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable output signal even if a temperature and a power supply voltage are fluctuated. <P>SOLUTION: A vibration gyrosensor 1 comprises: a vibrator 100; a monitor circuit 110; an amplitude adjusting circuit 114; a drive circuit 112; amplification circuits 202, 204 for amplifying signals obtained from a detection electrode in the vibrator, and outputting detection signals; a differential amplification circuit 206 for differentially amplifying two or more detection signals, and outputting a differentially-amplified signal; a synchronous wave detection circuit 208 for detecting a wave in the differentially-amplified signal in synchronization with a monitor signal, and outputting a wave detection signal; a filter circuit 216 for removing a noise from the wave detection signal, and outputting a filtered signal; a temperature sensor 214 for outputting a temperature signal dependent on an ambient temperature; a temperature-compensated ratio-metric circuit 300 fluctuated in proportion to a temperature compensation and a fluctuation in the power supply voltage relative to a sensitivity signal; and an offset adjusting circuit for adjusting an offset voltage within the vibration gyrosensor, and acquires a ratio-metric characteristic from a static voltage and the offset voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vibration gyro sensor used to detect angular velocity.

  2. Description of the Related Art In recent years, when a vehicle position is specified by a self-contained navigation in a car navigation device, a traveling direction is detected based on angular velocity information from a gyro sensor. Such a gyro sensor normally outputs an analog signal corresponding to the magnitude of the angular velocity. The analog signal is converted into a digital signal by an A / D converter, taken into a navigation system, and processed.

  When an analog signal is converted into a digital signal, the voltage width per resolution or the reference voltage may vary depending on the power supply voltage of the A / D converter. Therefore, it is necessary that the analog signal output from the gyro sensor also varies depending on the power supply voltage. In addition, a highly stable output signal is required with respect to temperature for in-vehicle use.

  In order to solve this problem, for example, Patent Document 1 proposes a gyro sensor having a ratiometric function that makes a detection signal dependent on a power supply voltage.

JP 2006-10408 A

  However, in Patent Document 1, there is a ratiometric circuit for a sensitivity signal, but since there is no temperature compensation, the sensitivity signal is unstable with respect to temperature.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vibration gyro sensor that can generate a stable output signal even with respect to fluctuations in temperature and power supply voltage.

  In order to solve the above problems, in the vibration gyro sensor of the present invention, a vibrator, a pair of drive electrodes for driving the vibrator, and two or more detections for detecting a Coriolis force applied to the vibrator. An electrode, a monitor circuit that is connected to one electrode of the pair of drive electrodes and outputs a monitor signal, a drive circuit that amplifies the monitor signal and outputs it to the other electrode of the pair of drive electrodes, An amplitude adjustment circuit that adjusts the amplitude of the output signal of the drive circuit to a constant, an amplification circuit that amplifies a signal obtained from the detection electrode of the vibrator and outputs a detection signal, and two or more detection signals A vibration gyro comprising: a differential amplification circuit that amplifies and outputs a differential amplification signal; a synchronous detection circuit that synchronously detects the differential amplification signal with the monitor signal and outputs a detection signal; and a filter circuit for noise removal Sensor The vibration gyro sensor further varies in proportion to a temperature sensor that outputs a temperature signal depending on an environmental temperature and a sensitivity signal output from the filter circuit with respect to temperature compensation and a variation in power supply voltage. An offset adjustment circuit for adjusting an offset voltage in the vibration gyro sensor, the amplifier circuit, the differential amplifier circuit, the synchronous detection circuit, and the filter circuit. The reference voltage of the temperature compensated ratiometric circuit has a circuit configuration that depends on the power supply, and the offset voltage and the quiescent voltage in a state where no Coriolis force is applied to the vibrator have a ratiometric characteristic. This is the gist.

  According to this configuration, since the temperature compensation type ratiometric circuit can compensate the temperature of the sensitivity signal based on the temperature signal depending on the environmental temperature, it is possible to suppress the influence of the temperature fluctuation of the sensitivity signal as much as possible.

  In the vibration gyro sensor of the present invention, the temperature compensation ratiometric circuit includes a ratiometric characteristic of the sensitivity signal and a temperature compensation of the sensitivity signal based on a reference voltage that depends on a power supply voltage and the voltage of the temperature signal. And do.

  According to this configuration, the sensitivity signal can be made to have a ratiometric characteristic based on the reference voltage that depends on the power supply voltage by the temperature compensated ratiometric circuit, so that it can be changed in proportion to the voltage fluctuation of the power supply voltage. .

  In the vibration gyro sensor of the present invention, the temperature compensation ratiometric circuit is a multiplier.

  According to this configuration, the circuit design can be facilitated by using the multiplier as the temperature compensation ratiometric circuit.

  In the vibration gyro sensor of the present invention, the temperature compensated ratiometric circuit is a Gilbert cell multiplier.

  According to this configuration, the circuit design can be facilitated by using the Gilbert cell multiplier as the temperature compensation ratiometric circuit.

  In the vibration gyro sensor of the present invention, the temperature compensated ratiometric circuit uses the reference voltage of each circuit as a power source voltage, thereby making the voltage at rest have a ratiometric characteristic.

  According to this configuration, since the quiescent voltage can have a ratiometric characteristic, the quiescent voltage can be changed in proportion to the fluctuation of the power supply voltage.

  In the vibration gyro sensor of the present invention, the offset adjustment circuit uses a reference voltage as a reference voltage depending on a power supply voltage, and the offset voltage has a ratiometric characteristic.

  According to this configuration, the temperature signal can be temperature-compensated based on the reference voltage depending on the power supply voltage by the temperature compensation ratiometric circuit, so that it can be changed in proportion to the voltage fluctuation of the power supply voltage.

  In the vibration gyro sensor of the present invention, the vibrator includes a base, a drive vibration system protruding from the base, and a plurality of detection vibration systems protruding from the base.

  In the vibration gyro sensor of the present invention, the filter circuit includes a switched capacitor filter, an LC filter, an RC filter, and an active filter using an operational amplifier.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.
(First embodiment)

<Configuration of vibration gyro sensor>
First, the configuration of the vibration gyro sensor according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of the vibration gyro sensor according to the first embodiment of the present invention.

  As shown in FIG. 1, the vibration gyro sensor 1 includes a vibrator 100, a monitor circuit 110, a drive circuit 112, an amplitude adjustment circuit 114, charge amplifier circuits 202 and 204 that are amplification circuits, and a differential amplification circuit. 206, synchronous detection circuit 208, filter circuit 216, zero point offset adjustment circuit 210, temperature compensation circuit 212, temperature sensor 214, temperature compensation ratiometric circuit 300, band gap reference circuit 320, reference A voltage generating circuit 322.

  Here, the configuration of the vibrator will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of the vibrator.

  As shown in FIG. 5, the vibrator 100 includes a base 10, a pair of drive vibration systems 30A and 30B, and a pair of detection vibration systems 31A and 31B. The base 10 of this example has a substantially square shape that is four-fold symmetric about the center of gravity GO of the vibrator (the center of gravity when the vibrator is not vibrating). The drive vibration systems 30A and 30B and the detection vibration systems 31A and 31B protrude from the sides of the peripheral edge 10a of the base 10, respectively.

  Each drive vibration system 30A, 30B includes a pair of elongated support portions 15A, 15B projecting in the radial direction from the peripheral edge portion 10a of the base portion 10, and a pair of each extending in a direction orthogonal to the longitudinal direction of the support portions 15A, 15B. Drive vibration pieces 16A, 16B, 16C, and 16D are provided. In this example, a wide weight part or hammer head 17A, 17B, 17C, 17D is provided at the tip of each drive vibration piece, and a through hole 12 is provided in each weight part.

  Each detection vibration system 31 </ b> A, 31 </ b> B includes an elongated detection vibration piece 20 that extends in a radial direction from the peripheral edge portion 10 a of the base portion 10. A wide weight part or hammer head 18A, 18B is provided at the tip of each detection vibrating piece 20, and a through hole 13 is provided in each weight part.

  Next, the operation of the vibrator 100 will be described. Using drive electrodes, which will be described later, the drive vibration pieces 16A and 16B are resonated in the same phase as indicated by arrow A, and the drive vibration pieces 16C and 16D are resonated in the same phase as indicated by arrow A. The center of gravity of the drive vibration of the bending vibration pieces 16A to 16D is set to be located on or near the center of gravity GO of the vibrator.

  In this state, when the vibrator 100 is rotated like ω in a predetermined plane (XY plane), the Coriolis force acts on the vibrator 100 during the rotation, so that each of the support portions 15A and 15B has an arrow B As described above, bending vibration is generated with the base 15a to the base 10 as the center. At this time, the phases of the bending vibrations of the support portions 15A and 15B are opposite to each other when viewed in the circumferential direction around the center of gravity GO. Corresponding to this, as shown by the arrow C, each detection vibrating piece 20 bends and vibrates around the root to the base 10. When each detection vibrating piece 20 is bent and vibrated, a signal voltage is generated at a detection electrode described later, and the rotational angular velocity is calculated from this signal voltage.

  Preferably, each drive vibration system is in a rotationally symmetric position about the center of gravity GO. This means that a plurality of drive vibration systems in question are separated from each other by the same predetermined angle within a predetermined plane with the center of gravity GO as the center. Therefore, when an operation of rotating one drive vibration system by a predetermined angle within a predetermined plane is performed, the drive vibration system is located at the position of another vibration system. For example, in FIG. 5, the vibration systems 30A and 30B are separated from each other by 180 °. Therefore, when an operation for rotating the vibration system 30A by 180 ° is performed, the vibration systems 30A and 30B come to the position of the vibration system 30B. The rotational symmetry is preferably 2-fold symmetry, 3-fold symmetry, and 4-fold symmetry.

  Next, the monitor circuit 110 in FIG. 1 is connected to the drive vibration system 30A of the vibrator 100, monitors the potential V1 of the drive vibration system 30A, and outputs a monitor signal V7. The drive circuit 112 is connected to the drive vibration system 30B of the vibrator 100, and outputs a drive signal V2 from the monitor signal V7. The amplitude adjustment circuit 114 is connected in parallel with the drive circuit 112 and adjusts the amplitude of the drive signal V2 to be constant. The monitor circuit 110, the drive circuit 112, and the amplitude adjustment circuit 114 operate at the output potential Vref1 of the band gap reference circuit 320.

  The charge amplifier circuit 202 is connected to the detection vibration system 31B of the vibrator 100, amplifies the signal V3, and outputs a detection signal V5. The charge amplifier circuit 204 is connected to the detection vibration system 31A of the vibrator 100, amplifies the signal V4, and outputs a detection signal V6. The differential amplifier circuit 206 is connected to the charge amplifier circuits 202 and 204, differentially amplifies the detection signals V5 and V6, and outputs a differential amplified signal V8.

  The synchronous detection circuit 208 is connected to the differential amplifier circuit 206 and the monitor circuit 110, synchronously detects the differential amplified signal V8 with the monitor signal V7, and outputs a detection signal V9.

  The zero point offset adjustment circuit 210 adjusts the offset of the stationary signal with respect to the detection signal V9. The temperature sensor 214 outputs a temperature signal Vtemp having a voltage depending on the environmental temperature. The temperature compensation circuit 212 is connected to the temperature sensor 214 and compensates the temperature of the detection signal V9 with the temperature signal Vtemp.

  The filter circuit 216 is connected to the synchronous detection circuit 208 and outputs a filter signal Vin + Vref from which noise is removed.

  The temperature compensation ratiometric circuit 300 is connected to the filter circuit 216 and the temperature sensor 214, and outputs a sensitivity signal Vout + Vref from the temperature signal Vtemp, the reference voltage Vref, and the filter signal Vin + Vref.

  The charge amplifier circuits 202 and 204, the differential amplifier circuit 206, the synchronous detection circuit 208, the zero-point offset adjustment circuit 210, the temperature compensation circuit 212, the filter circuit 216, and the temperature compensation ratiometric circuit 300 are output from the reference voltage generation circuit 322. The reference voltage Vref operates.

<Output signal of vibration gyro sensor>
Here, the output signal of the vibration gyro sensor will be described with reference to FIG. FIG. 4 is a graph showing an output signal of the vibration gyro sensor.

  As shown in FIG. 4, the output signal of the angular velocity sensor is roughly composed of three signals: a sensitivity signal, a stationary voltage, and an offset voltage.

  As the sensitivity signal, the charge generated from the vibrator 100 by the Coriolis force is output as a filter signal Vin + Vref by the charge amplifier circuits 202 and 204, the differential amplifier circuit 206, the synchronous detection circuit 208, and the filter circuit 216. The voltage at rest is Vdd / 2 of the power supply voltage Vdd or a voltage desired by the user and is a voltage in a state where no angular velocity is applied, and is a reference voltage of the vibration gyro sensor 1. The offset voltage is an offset voltage generated from a leakage signal from the vibrator 100, an amplifier of the vibration gyro sensor 1, or the like.

<Configuration of temperature compensated ratiometric circuit>
Next, the configuration of the temperature compensation ratiometric circuit will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the temperature compensation ratiometric circuit.

  As shown in FIG. 2, the temperature compensation ratiometric circuit 300 includes an operational amplifier 308, resistors R5, R6, R7, and R8, an analog multiplier 306, and a voltage-current converter 310. .

  The reference voltage generation circuit 322 includes an operational amplifier 302 and resistors R1 and R2. The bandgap reference circuit 320 includes an operational amplifier 304 and resistors R3 and R4.

  Resistors R1 and R2 are connected in series between the power supply voltage Vdd and the ground potential, and the positive terminal of the operational amplifier 302 is connected to the connection point of the resistors R1 and R2. Further, the negative terminal and the output terminal of the operational amplifier 302 are connected to each other. A reference voltage Vref, which is an output voltage of the operational amplifier 302, is Vref = Vdd × R1 / R2.

  Resistors R3 and R4 are connected in series between the power supply voltage Vdd and the ground potential, and the positive terminal of the operational amplifier 304 is connected to the connection point of the resistors R3 and R4. Further, the negative terminal and the output terminal of the operational amplifier 304 are connected to each other. The auxiliary voltage Vref1, which is the output voltage of the operational amplifier 304, is Vref1 = Vdd × R3 / R4.

  The voltage-current converter 310 is connected between the power supply voltage Vdd and the analog multiplier 306. Further, the temperature signal Vtemp that is the output voltage of the temperature sensor 214 is input to the voltage terminal side, and the temperature signal Vtemp is converted into a current. The current value Itemp is output to the analog multiplier 306.

  The analog multiplier 306 receives the filter signal Vin + Vref that is the output voltage of the filter circuit 216, the output voltage Vref of the operational amplifier 302, and the output voltage Vref1 of the operational amplifier 304.

  The operational amplifier 308 has a + terminal connected to the analog multiplier 306 via the resistor R5 and a − terminal connected to the analog multiplier 306 via the resistor R6. Further, the output voltage Vref of the operational amplifier 302 is connected to the − terminal via a resistor R7, and the + terminal is connected to the output terminal via a resistor R8. The output terminal of the operational amplifier 308 outputs a sensitivity signal Vout + Vref.

  When gm is a scale factor, the potential difference ΔV between the output terminals of the analog multiplier 306 is ΔV = gm × {(Vin + Vref) −Vref} × (Vref1−Vref) = gm × {(Vin + Vref) −Vref} × (R3 / R4-R1 / R2) × Vdd. Further, assuming that the operational amplifier 308 is A times, Vout is Vout = A * gm * Vin * (R3 / R4-R1 / R2) * Vdd + (R1 / R2) * Vdd.

  As a result, Vout is temperature-compensated by fluctuation of the parameter Itemp forming gm. The power supply voltage Vdd is ratiometrically expressed by (R3 / R4-R1 / R2) × Vdd.

  According to the embodiment described above, the following effects can be obtained.

  In this embodiment, a temperature dependent voltage is provided in the temperature compensation ratiometric circuit, and the temperature variation of the sensitivity signal can be suppressed as much as possible by compensating the temperature of the sensitivity signal, and the temperature compensation circuit is provided in the temperature compensation ratiometric circuit. As a result, the circuit can be reduced in size.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, In the range which does not deviate from the meaning of this invention, it can be implemented with various forms. Hereinafter, a modification will be described.

  (Modification 1) A first modification of the vibration gyro sensor according to the present invention will be described. In the first embodiment, the temperature-compensated ratiometric circuit 300 as shown in FIG. 2 is proposed. However, the temperature-compensated ratiometric circuit 300 as shown in FIG. 3 can be realized. FIG. 3 is a block diagram illustrating a configuration of a temperature compensation ratiometric circuit according to the first modification.

  As shown in FIG. 3, the temperature compensated ratiometric circuit 300 according to the first modification includes a temperature dependent constant current source 324, a first differential amplifier 326, a power supply dependent constant current source 328, and a second differential amplifier. 330 and a current-voltage conversion circuit 332.

  The band gap reference circuit 320 outputs a fixed voltage Vref1. The reference voltage generation circuit 322 has a reference voltage Vref = (R9 / R10) × Vdd.

  The temperature-dependent constant current source 324 receives Vdd, a fixed voltage Vref1, and a temperature signal Vtemp. The first differential amplifier 326 receives two output signals of the filter signal Vin + Vref, the reference voltage Vref, and the temperature-dependent constant current source 324.

  The power supply dependent constant current source 328 receives Vdd and the reference voltage Vref. The second differential amplifier 330 receives the two output signals of the first differential amplifier 326 and the output signal of the power supply dependent constant current source 328. The current-voltage conversion circuit 332 receives the two output signals of the second differential amplifier 330 and the reference voltage Vref, and outputs a sensitivity signal Vout + Vref subjected to sensitivity ratiometric and sensitivity temperature compensation.

The block diagram which shows the structure of the vibration gyro sensor which concerns on 1st Embodiment. 1 is a block diagram showing a configuration of a temperature compensation ratiometric circuit according to a first embodiment. The block diagram which shows the structure of the temperature compensation type | mold ratiometric circuit which concerns on the modification 1. FIG. The graph figure which shows the output signal of an angular velocity sensor. The block diagram which shows the structure of a vibrator | oscillator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vibration gyro sensor, 100 ... Vibrator, 110 ... Monitor circuit, 112 ... Drive circuit, 114 ... Amplitude adjustment circuit, 202, 204 ... Charge amplifier circuit, 206 ... Differential amplifier circuit, 208 ... Synchronous detection circuit, 210 ... 0 point offset adjustment circuit, 212 ... temperature compensation circuit, 214 ... temperature sensor, 216 ... filter circuit, 300 ... temperature compensation ratiometric circuit, 302, 304, 308 ... operational amplifier, 306 ... analog multiplier, 310 ... voltage- Current converter 320... Band gap reference circuit 322. Reference voltage generation circuit 324... Temperature dependent constant current source 326... First differential amplifier 328. 332: Current-voltage conversion circuit.

Claims (8)

A vibrator,
A pair of drive electrodes for driving the vibrator;
Two or more detection electrodes for detecting Coriolis force applied to the vibrator;
A monitor circuit connected to one electrode of the pair of drive electrodes and outputting a monitor signal;
A drive circuit for amplifying the monitor signal and outputting the amplified signal to the other electrode of the pair of drive electrodes;
An amplitude adjustment circuit for adjusting the amplitude of the output signal of the drive circuit to be constant;
An amplification circuit for amplifying a signal obtained from the detection electrode of the vibrator and outputting a detection signal;
A differential amplifier circuit that differentially amplifies two or more detection signals and outputs a differential amplified signal;
A synchronous detection circuit for synchronously detecting the differential amplification signal with the monitor signal and outputting a detection signal;
A filter circuit for noise removal;
In the vibration gyro sensor consisting of
The vibration gyro sensor further includes:
A temperature sensor that outputs a temperature signal depending on the environmental temperature;
A temperature compensated ratiometric circuit that varies in proportion to temperature compensation and fluctuations in power supply voltage with respect to the sensitivity signal output from the filter circuit;
Have
Further, an offset adjustment circuit for adjusting an offset voltage in the vibration gyro sensor, a reference voltage of the amplifier circuit, the differential amplifier circuit, the synchronous detection circuit, the filter circuit, and the temperature compensation ratiometric circuit is used as a power source. It has a circuit configuration that depends, and the offset voltage and the resting voltage in a state where no Coriolis force is applied to the vibrator have a ratiometric characteristic.
This is a vibration gyro sensor.   2. The vibration gyro sensor according to claim 1, wherein the temperature compensation ratiometric circuit includes a ratiometric characteristic of the sensitivity signal and a temperature of the sensitivity signal based on a reference voltage depending on a power supply voltage and the voltage of the temperature signal. A vibration gyro sensor characterized by performing compensation.   2. The vibration gyro sensor according to claim 1, wherein the temperature compensation ratiometric circuit is a multiplier.   2. The vibration gyro sensor according to claim 1, wherein the temperature compensation ratiometric circuit is a Gilbert cell multiplier.   5. The vibration gyro sensor according to claim 1, wherein the stationary voltage has a ratiometric characteristic by making a reference voltage of each circuit dependent on a power supply voltage. Sensor.   6. The vibration gyro sensor according to claim 1, wherein the offset adjustment circuit uses a reference voltage as a reference voltage that depends on a power supply voltage, and the offset voltage has a ratiometric characteristic. Vibration gyro sensor.   7. The vibration gyro sensor according to claim 1, wherein the vibrator includes a base, a drive vibration system protruding from the base, and a plurality of detection vibration systems protruding from the base. Vibration gyro sensor characterized by. 8. The vibration gyro sensor according to claim 1, wherein the filter circuit includes an active filter using a switched capacitor filter, an LC filter, an RC filter, and an operational amplifier. Sensor.

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