JP2010054404A - Oscillation gyro sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oscillation gyro sensor, capable of accurately detecting angular velocity without being affected by temperature change or the like by individually correcting an electric leak signal component and a mechanical leak signal component of an oscillator. <P>SOLUTION: In the oscillation gyro sensor including an oscillator 1, and an oscillation circuit 20 which applies a drive signal P5 to the oscillator 1 and oscillates the oscillator 1 in response to a feedback signal P1 from the oscillator 1, the oscillator 1 outputting detection signals P10a and P10b according to an applied angular velocity, the sensor includes a first correction circuit 40 which generates first correction signals H1a and H1b for correcting the detection signals P10a and P10b based on the drive signal P5; and a second correction circuit 50 which generates second correction signals H2a and H2vb for correcting the detection signals P10a and P10b based on the feedback signal P1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vibration gyro sensor as an angular velocity sensor used in attitude control, navigation systems, and the like of automobiles and robots.

  Conventionally, a vibration type gyro sensor that detects an angular velocity using a piezoelectric vibrator or the like is an indispensable sensor for performing attitude control of an automobile or a robot, and the demand for a car navigation system or a robot increases. There is an increasing demand for vibration gyro sensors with high accuracy and a wide operating temperature range. However, the vibration-type gyro sensor has a problem that a leak signal component (noise signal component) is generated in the detection signal due to a plurality of factors when the angular velocity is not applied, and the detection accuracy of the angular velocity is lowered. In order to cope with this problem, an angular velocity sensor that corrects an angular velocity detection error caused by the mass balance of the vibrator has been disclosed (see, for example, Patent Document 1).

  Hereinafter, Patent Document 1 as a conventional technique will be described with reference to the drawings. FIG. 10 is a block diagram of a conventional angular velocity sensor. In FIG. 10, the conventional angular velocity sensor includes a tuning fork type vibrator 100 made of a piezoelectric element, and a control circuit unit 110 that drives the vibrator 100 and detects the angular velocity applied to the vibrator 100.

  The vibrator 100 is provided with a drive electrode unit 101 that inputs a drive signal P101 for vibrating at a specific frequency, a monitor electrode unit 102 that detects a vibration frequency of the vibrator 100 and outputs it as a feedback signal P102, and the vibrator 100. And a sense electrode unit 103 that outputs detection signals P103a and P103b corresponding to the angular velocity.

  The control circuit unit 110 includes a monitor circuit unit 120 that inputs the feedback signal P102 of the transducer 100, an AGC circuit 111 connected to the monitor circuit unit 120, a drive circuit unit 112 connected to the AGC circuit 111, and the transducer An angular velocity detection circuit unit 130 for inputting 100 detection signals P103a and P103b is provided.

  The monitor circuit unit 120 includes an amplifier 121 to which a feedback signal P102 is input, a band pass filter (BPF) 122, a rectifier 123, and a smoothing circuit 124. The AGC circuit 111 receives the output signal of the smoothing circuit 124 and controls the drive circuit unit 112 so that the output signal of the BPF 122 is amplified or attenuated according to the input signal.

  The drive circuit unit 112 amplifies or attenuates the output signal from the BPF 122 under the control of the AGC circuit 111, and outputs the amplified signal to the drive electrode unit 101 as a drive signal P 101 for driving the transducer 100. Keep it constant. The angular velocity detection circuit unit 130 includes two amplifiers 131 and 132 that amplify the detection signals P103a and P103b, a differential amplifier 133, a phase shifter 134, a synchronous detection unit 135, and an LPF 136, and outputs an angular velocity output P110.

  Further, the control circuit unit 110 includes a correction circuit unit 140 that removes signal components of the detection signals P103a and P103b, which are erroneously detected as having an angular velocity when the transducer 100 has no angular velocity, as noise signal components. Is provided. The noise signal component includes a first noise signal component and a second noise signal component.

The first noise signal component is generated in a state where the phase is not shifted from the feedback signal P <b> 102, and the first noise signal component is generated due to the mass balance of the vibrator 100. For example, in the case of a U-shaped or H-shaped tuning fork type vibrator 100, a first noise signal component is generated if the mass of each arm varies. Further, the second noise signal component is generated due to a state in which the phase is shifted with respect to the feedback signal P102.

  The correction circuit unit 140 includes a first noise correction circuit 141 for removing the first noise signal component and a second noise correction circuit 142 for removing the second noise signal component. Although not shown, the first noise correction circuit 141 and the second noise correction circuit 142 are formed by combining a switch portion and a ladder resistor.

  The first noise correction circuit 141 adjusts the resistance value of the ladder resistor according to the data stored in the memory unit 113, attenuates the output signal from the amplifier 121, and generates the correction signal P104a. It superimposes on both detection signals output from the amplifiers 131 and 132 of the detection circuit unit 130, and removes the first noise signal component contained in both detection signals.

  The second noise correction circuit 142 adjusts the resistance value of the ladder resistor according to the data stored in the memory unit 113, attenuates the output signal from the amplifier 121, and generates the correction signal P104b. Is superimposed on the detection signals output from the amplifiers 131 and 132, and the second noise signal component contained in both detection signals is removed. Note that the second noise correction circuit 142 incorporates a phase shifter 143, and adopts a method in which the phase shifter 143 matches the phase of the output signal from the amplifier 121 with the phase of the second noise signal component.

  The memory unit 113 stores data used when the first noise correction circuit 141 and the second noise correction circuit 142 generate correction signals for removing the first and second noise signal components from the detection signal. I remember it.

  As described above, the angular velocity sensor described in Patent Document 1 as a conventional technique includes the first and second noise correction circuits, the first noise signal component resulting from the mass balance of the vibrator, and this It is shown that since the second noise signal component having a phase different from that of the first noise signal component is removed, the angular velocity can be detected with high accuracy.

  In addition, in a conventional angular velocity sensor having a vibrator (not shown), if a leakage signal component occurs due to a variation in the orthogonal accuracy of the transducer and the angular velocity is zero, the leakage signal component is converted into a feedback signal from the transducer. When the phase is the same, a fixed amount of a correction signal obtained by inverting the feedback signal is added to the detection signal to cancel the leakage signal component. When the leakage signal component is a signal component that is 180 degrees out of phase with the feedback signal, An angular velocity sensor that cancels a signal component by adding a fixed amount of a correction signal that is a non-inverted feedback signal to a detection signal has been disclosed (for example, see Patent Document 2).

  This conventional angular velocity sensor has a configuration in which a correction signal is added to a detection signal by a resistance element or a capacitive element, and a leakage signal component generated when the angular velocity is zero can be canceled. It is shown that there are effects such as reduction and noise reduction.

International Publication No. WO2005 / 080919 (5th page, Fig. 1) Japanese Patent Laid-Open No. 04-295716 (page 3, FIG. 1)

However, the angular velocity sensor of Patent Document 1 includes two correction circuits, and a first noise signal component that is not out of phase with respect to the feedback signal and a second noise signal component that is out of phase with respect to the feedback signal. However, the two correction circuits both receive a feedback signal, and a phase shifter is provided for the second noise signal component that is out of phase, and the correction signal is converted to the second noise by the phase shifter. An attempt is made to remove a noise signal component in accordance with the phase of the signal component.

  However, it is difficult to adjust the phase of the feedback signal slightly to match the phase of the noise signal component, and it is difficult to adjust the phase of the feedback signal. Therefore, there is a problem that the phase of the correction signal is shifted. In particular, since the required operating temperature range is wide in an in-car car navigation system or the like, if the correction circuit has temperature characteristics, the correction state changes due to a temperature change, and accurate angular velocity detection becomes extremely difficult. In addition, by configuring the phase shifter inside the correction circuit, the circuit scale of the correction circuit increases, which hinders downsizing and cost reduction of the angular velocity sensor.

  As for the angular velocity sensor disclosed in Patent Document 2, the leakage signal component from the angular velocity sensor includes a mechanical leakage signal component due to variations in vibrator shape and the like, and an electrical leakage signal component due to the capacitance between the drive electrode and the detection electrode. There is a phase difference between the two leakage signal components. For this reason, in order to cancel both the mechanical leakage signal component and the electrical leakage signal component, a correction circuit for correcting the leakage signal components having different phases is required. However, in this conventional example, only the correction signal inverted with respect to the feedback signal or the non-inversion correction signal is added to the detection signal. Therefore, it is not possible to remove two types of leak signal components having different phases. I can't. In addition, the correction signal is added to the detection signal by connecting a resistance element or a capacitance element, but it is clear whether the resistance element is used for any leakage signal component or the capacitance element is used. However, the content of the invention is not clear.

  The object of the present invention is to solve the above-mentioned problems, and by correcting the electrical leakage signal component and mechanical leakage signal component of the vibrator individually, vibration that can detect angular velocity with high accuracy without being affected by temperature change etc. It is to provide a type gyro sensor.

  In order to solve the above problems, the vibration gyro sensor of the present invention employs the following configuration.

  The vibration-type gyro sensor of the present invention includes a vibrator and an oscillation circuit that applies a drive signal to the vibrator and receives a feedback signal from the vibrator and oscillates the vibrator. In a vibration type gyro sensor that outputs a detection signal corresponding to an angular velocity, a first correction circuit that corrects an electric leakage signal component of the detection signal based on the drive signal, and a machine of the detection signal based on the feedback signal And a second correction circuit for correcting the signal component.

  In addition to the above-described configuration, the vibration type gyro sensor of the present invention includes a first correction circuit including an amplitude adjustment circuit, an inverting circuit, and a capacitive element.

  Furthermore, in addition to the configuration described above, the vibratory gyro sensor of the present invention outputs a first detection signal and a second detection signal, and the second correction circuit includes an amplitude adjustment circuit and an inverting circuit. The first detection signal is corrected with one of the signal inverted by the inverting circuit and the non-inverted signal, and the second detection signal is corrected with the other signal.

  Furthermore, in the vibration gyro sensor of the present invention, in addition to the above-described configuration, the second correction circuit includes a switching circuit that switches a signal inverted by the inverting circuit and a non-inverted signal.

  Further, the vibration gyro sensor of the present invention includes a control circuit for controlling the amplitude adjustment amount by the amplitude adjustment circuit in addition to the above-described configuration.

  Furthermore, the vibration type gyro sensor of the present invention includes a control circuit for controlling the switching circuit in addition to the above-described configuration.

  In the present invention, the first correction circuit corrects the electric leakage signal component based on the drive signal, and the second correction circuit corrects the mechanical leakage signal component based on the feedback signal. As described above, the electrical leakage signal component and the mechanical leakage signal component are individually corrected by the two correction circuits, thereby reducing the influence of the leakage signal component and providing a highly accurate vibration-type gyro sensor. I can do it. In addition, the two correction circuits do not require a phase shifter to adjust the phase of the leak signal component, so that the leak signal component is corrected without being affected by variations in circuit elements, changes over time, temperature characteristics, etc. Therefore, it is possible to realize a vibration type gyro sensor having stable detection characteristics.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an outline of a vibration type gyro sensor according to a first embodiment of the present invention. FIG. 2 is a perspective view of the vibrator of the vibration type gyro sensor of the present invention. FIG. 3 is a sectional view showing the electrode structure of the vibrator of the vibration type gyro sensor of the present invention. FIG. 4 is a complex plan view showing the relationship between the drive signal and the electric leakage signal component and the relationship between the feedback signal and the mechanical leakage signal component of the vibration type gyro sensor of the present invention. FIG. 5 is a complex plan view for explaining the operation of the first correction circuit of the vibration type gyro sensor of the present invention. FIG. 6 is a complex plan view for explaining the operation of correcting the mechanical leakage signal component in the opposite phase to the feedback signal of the second correction circuit of the vibration type gyro sensor of the present invention. FIG. 7 is a complex plan view for explaining the operation of correcting the mechanical leakage signal component in the same phase with respect to the feedback signal of the second correction circuit of the vibration type gyro sensor of the present invention. FIG. 8 is a flowchart for explaining the correction adjustment work of the vibration type gyro sensor of the present invention. FIG. 9 is a block diagram showing an outline of the vibration type gyro sensor according to the second embodiment of the present invention.

  First, based on FIG. 1, the structure of Example 1 of the vibration-type gyro sensor of this invention is demonstrated. The feature of the first embodiment is a vibration type gyro sensor suitable for cases where the phase of the mechanical leakage signal component is limited by adding vibration to the vibration of the vibrator. In FIG. 1, the vibration type gyro sensor of the present invention includes a vibrator 1 made of a crystal vibrator or the like and a control IC 10 that drives the vibrator 1 to detect an angular velocity.

  Here, the vibrator 1 includes a pair of drive electrodes 3 and 4 and a pair of detection electrodes 5 and 6. The detailed structure will be described later. The control IC 10 includes an oscillation circuit 20 that oscillates the vibrator 1, a detection circuit 30 that receives a detection signal generated due to the angular velocity applied to the vibrator 1 and outputs an output signal corresponding to the angular velocity to the outside. The first correction circuit 40 corrects the electric leakage signal component, the second correction circuit 50 corrects the mechanical leakage signal component, and the control circuit 11 including a memory for storing information.

  The oscillation circuit 20 of the control IC 10 includes a current-voltage conversion circuit 21 (hereinafter abbreviated as I / V conversion circuit 21), a phase shift circuit 22, an amplitude detection circuit 23, a variable gain amplification circuit 24, and the like. Here, the I / V conversion circuit 21 receives the feedback signal P1 that flows out from one drive electrode 4 in response to the vibration of the vibrator 1, performs current-voltage conversion, and outputs the feedback voltage signal P2. Since the phase is inverted by the I / V conversion circuit 21, the feedback voltage signal P2 has a phase opposite to that of the feedback signal P1.

  The phase shift circuit 22 receives the feedback voltage signal P2, shifts the phase of the feedback voltage signal P2 so as to meet the conditions for the vibrator 1 to oscillate, and outputs the phase shift signal P3. The amplitude detection circuit 23 receives the feedback voltage signal P2 and outputs an AGC signal P4 corresponding to the amplitude of the feedback voltage signal P2. The variable gain amplifier 24 varies the gain according to the AGC signal P4, variably amplifies the input phase shift signal P3, and applies the drive signal P5 to the drive electrode 3 of the vibrator 1. Thereby, the oscillation circuit 20 can oscillate the vibrator 1, adjust the magnitude of the drive signal P5 according to the feedback signal P1, and always keep the vibration amplitude of the vibrator 1 in a constant state.

  Next, the configuration of the detection circuit 30 of the control IC 10 will be described. The detection circuit 30 includes two displacement detection circuits 31, 32, a differential amplifier circuit 33, a synchronous detection circuit 34, an amplifier circuit 35, a low-pass filter 36 (hereinafter abbreviated as LPF 36), and the like. Here, the two displacement detection circuits 31 and 32 are connected to the detection electrodes 5 and 6 of the vibrator 1, respectively, receive the detection signals P10a and P10b, and output the detection voltages P11a and P11b that are voltage values. The differential amplifier circuit 33 receives the detection voltages P11a and P11b, performs differential amplification, and outputs a differential output P12.

  The synchronous detection circuit 34 receives the differential output P12, performs synchronous detection based on a detection control signal output from the oscillation circuit 20 (not shown), and outputs a detection output P13. The amplification circuit 35 receives and amplifies the detection output P13, and the LPF 36 cuts a high frequency component of the amplified signal and outputs an angular velocity output Po corresponding to the angular velocity applied to the vibrator 1. Thereby, the detection circuit 30 can input the detection signals P10a and P10b from the vibrator 1 and output the magnitude of the angular velocity applied to the vibrator 1 as an electric signal. The detection voltage P11a is output from the monitor terminal 12 to the outside as a monitor signal. The monitor signal is not limited to the detection voltage P11a, and the detection voltage P11b or the differential output P12 may be used.

  Next, the configuration of the first correction circuit 40 will be described. The first correction circuit 40 is a circuit that corrects an electric leakage signal component of the vibrator 1 and includes an inversion circuit 41, an amplitude adjustment circuit 42, capacitors C1 and C2 as two capacitance elements, and the like. Here, the inverting circuit 41 receives the driving signal P5 from the oscillation circuit 20, and outputs a driving inversion signal P15 in which the phase of the driving signal P5 is inverted by 180 degrees. The amplitude adjustment circuit 42 includes a ladder resistor, a switch, and the like (not shown), receives the drive inversion signal P15, adjusts the amplitude of the drive inversion signal P15 according to the amplitude adjustment signal P16 from the control circuit 11, and The correction signal H1 is output. Thus, the first correction signal H1 is a signal that is inverted by 180 degrees to the phase of the drive signal P5.

  Further, the capacitor C1 receives the first correction signal H1, outputs the first correction signal H1a obtained by advancing the phase of the first correction signal H1 by 90 degrees, and adds it to the detection signal P10a. Thus, the first correction signal H1a is superimposed on the detection signal P10a. Similarly, the capacitor C2 receives the first correction signal H1, outputs the first correction signal H1b obtained by advancing the phase of the first correction signal H1 by 90 degrees, and adds it to the detection signal P10b. Thereby, the first correction signal H1b is superimposed on the detection signal P10b.

  Next, the configuration of the second correction circuit 50 will be described. The second correction circuit 50 is a circuit that corrects a mechanical leakage signal component of the vibrator 1 and includes an amplitude adjustment circuit 51, an inverting circuit 52, resistors R1 and R2 as two resistance elements, and the like. Here, the amplitude adjustment circuit 51 includes a ladder resistor, a switch, and the like (not shown), receives the feedback voltage signal P2 from the oscillation circuit 20 obtained by converting the feedback signal P1 into a current voltage, and adjusts the amplitude from the control circuit 11. The amplitude of the feedback voltage signal P2 is adjusted according to the signal P17, and the second correction signal H2 is output. The inversion circuit 52 receives the second correction signal H2 and outputs a second correction inversion signal H2v obtained by inverting the second correction signal H2 by 180 degrees. As a result, the second correction signal H2 has a phase opposite to that of the feedback voltage signal P2, that is, a signal having the same phase as that of the feedback signal P1. The second corrected inversion signal H2v is a signal having the same phase as the feedback voltage signal P2, that is, a signal having an opposite phase to the feedback signal P1.

  The resistor R1 receives the second correction signal H2 and converts the voltage into current according to the resistance value of the resistor R1, thereby outputting the second correction signal H2a having the same phase and adding it to the detection signal P10a. Thereby, the second correction signal H2a is superimposed on the detection signal P10a. Similarly, the resistor R2 receives the second corrected inverted signal H2v, converts the voltage from the voltage to the current according to the resistance value of the resistor R2, and outputs the second corrected inverted signal H2vb having the same phase to the detection signal P10b. Add. As a result, the second correction inversion signal H2vb is superimposed on the detection signal P10b.

  With the above configuration, the displacement detection circuit 31 receives the first correction signal H1a and the second correction signal H2a superimposed on one of the pair of detection signals P10a from the vibrator 1, and the displacement detection circuit 31 32, the first correction signal H1b and the second correction inversion signal H2vb are superimposed on the other detection signal P10b to be paired from the vibrator 1 and input.

  The control circuit 11 is connected to an I / F terminal 13 for inputting / outputting information from / to the outside, and stores control information from the outside in an internal memory via the I / F terminal 13, and if necessary The amplitude adjustment signals P16 and P17 are output to control the operations of the first correction circuit 40 and the second correction circuit 50. The memory built in the control circuit 11 is preferably a nonvolatile memory.

  Next, an example of a vibrator used in the vibration type gyro sensor of the present invention will be described with reference to FIGS. In the perspective view of FIG. 2, electrodes are omitted. 2 and 3, the vibrator 1 is a quartz vibrator having a resonance frequency of several tens of kHz made of quartz that is a single crystal of Si02, and includes two drive branches 2a and 2b and one detection branch 2c. This is a tripod tuning fork vibrator having three branches and a base 8 and a support 9. Further, a pair of drive electrodes 3 and 4 are formed on the drive branches 2a and 2b. The drive electrode 3 is connected to the drive electrodes 3a and 3b formed on the two opposing surfaces of the drive branch 2a. It consists of drive electrodes 3c and 3d formed on two opposing surfaces of the branch 2b.

  Further, the drive electrode 4 is composed of drive electrodes 4a and 4b formed on the other two surfaces facing the drive branch 2a and drive electrodes 4c and 4d formed on the other two surfaces opposed to the drive branch 2b. Become. These drive electrodes 3a, 3b, 3c, and 3d are electrically connected and connected to the outside, respectively, and the drive electrodes 4a, 4b, 4c, and 4d are also electrically connected and connected to the outside. .

  The detection branch 2c is formed with a pair of detection electrodes 5 and 6 at the corners thereof and is connected to the outside. The electrodes on the surface facing the detection electrodes 5 and 6 are connected to the GND of the circuit. Further, the structure of the vibrator 1 is not limited to a tripod tuning fork vibrator as shown in FIGS. 2 and 3, but may be a bipod tuning fork vibrator, for example.

  Next, the angular velocity detection operation of the vibration type gyro sensor according to the present invention will be described with reference to FIGS. Here, as described above, the vibrator 1 continues to oscillate at a constant amplitude by the oscillation circuit 20 of the control IC 10. If the vibrator 1 is rotated at the angular velocity ω at this time, the vibrator 1 is shown in FIG. A Coriolis force F proportional to the angular velocity ω acts in the Z direction perpendicular to the vibration in the arrow X direction. This Coriolis force F is represented by F = 2 · m · ω · V: Formula 1, where m is an equivalent mass of the driving branches 2a and 2b or the detecting branch 2c, and V is a resonance frequency f0 (Hz ). Due to the stress caused by the Coriolis force F, the vibrator 1 is excited to vibrate at a frequency equal to the resonance frequency in the Z direction shown in FIG. 3, and this vibration causes piezoelectric strain on the detection electrodes 5 and 6 formed on the detection branch 2c. Charge due to the effect is generated.

Due to the generated charges, minute detection signals P10a and P10b having opposite phases are generated in the detection electrodes 5 and 6. The displacement detection circuits 31 and 32 of the detection circuit 30 detect the detection signals P10a and P10.
b is converted into a current voltage, and detection voltages P11a and P11b are output. The differential amplifier 33 amplifies the difference between the detection voltages P11a and P11b, and outputs a differential output P12. The synchronous detection circuit 34 receives the differential output P12, performs synchronous detection in accordance with the timing of a detection control signal (not shown) output from the oscillation circuit 20, and outputs a detection output P13 converted to direct current. . The amplifier circuit 35 and the LPF 36 amplify the detection output P13, cut the AC component, and output an angular velocity output Po that is a DC voltage corresponding to the angular velocity.

  Next, based on FIG. 4, the electric leakage signal component L1 and the mechanical leakage signal components L2a and L2b of the vibration type gyro sensor, which are errors in angular velocity detection, will be described. FIG. 4 shows the electrical leakage signal component L1 and the mechanical leakage signal components L2a and L2b for the feedback signal P1, the feedback voltage signal P2, and the drive signal P5 by a complex plane with the X axis as the real part and the Y axis as the imaginary part. ing. In FIG. 4, the feedback signal P1 from the vibrator 1 is shown on the −X axis. Then, since the phase is inverted by the I / V conversion circuit 21, the feedback voltage signal P2 can be expressed as a vector in the + X direction. The phase of the drive signal P5 is inverted by 180 degrees by the variable gain amplifier 24 with respect to the feedback voltage signal P2, but if the phase shift circuit 22 advances by about 30 degrees as an example, the phase is shifted by about 150 degrees. , Shown as a vector in the third quadrant as shown. The amount of phase shift by the phase shift circuit 22 is not limited to this example.

  Here, the electric leakage signal component L1 is a signal component that is mainly generated when the drive signal P5 is transmitted to the detection electrodes 5 and 6 by capacitive coupling between the electrodes of the vibrator 1, and the drive signal P5 is used for capacitive coupling. It is generated in the detection electrodes 5 and 6 as a signal component whose phase is advanced by 90 degrees. Therefore, as shown in FIG. 4, the electric leakage signal component L1 is a signal whose phase is advanced by about 90 degrees with respect to the drive signal P5, and can be shown as a vector in the fourth quadrant as shown.

  Next, the machine leakage signal components L2a and L2b are signal components generated by imbalance of the vibration of the vibrator 1, and the phase thereof is the same as that of the vibration of the vibrator 1 (phase difference is zero) or opposite phase (phase difference). 180 degrees). Here, since the vibration of the vibrator 1 has the same phase as the feedback signal P1, the mechanical leakage signal components L2a and L2b are generated as signal components having the same phase or opposite phase as the feedback signal P1.

  Specifically, the mechanical leakage signal component is generated at the two detection electrodes 5 and 6 of the vibrator 1, but as an example, the mechanical leakage signal component L2a generated from one detection electrode 5 is in phase with the feedback signal P1. Then, the machine leakage signal component L2b generated from the other detection electrode 6 has an opposite phase to the feedback signal P1. That is, the mechanical leakage signal component is generated from the two detection electrodes 5 and 6 of the vibrator 1 as two mechanical leakage signal components L2a and L2b that are inverted by 180 degrees.

Therefore, as shown in FIG. 4, the machine leakage signal component includes a vector of the machine leakage signal component L2a having an antiphase with respect to the feedback signal P1, and a machine leakage signal component L2b having an antiphase with respect to the feedback signal P1. It can be shown as a vector. In addition, the length of each vector is an example and is not limited.
As described above, the vibration type gyro sensor generates an electrical leakage signal component and a mechanical leakage signal component in a state where the angular velocity is not applied, thereby reducing the detection accuracy of the angular velocity. A major feature is to realize highly accurate angular velocity detection by individually correcting the component and the machine leakage signal component.

Next, the operation of the first correction circuit 40 for correcting and reducing the electric leakage signal component will be described based on the complex plan view of FIG. Refer to the block diagram of FIG. 1 for the configuration of the vibration type gyro sensor. In FIG. 5, the drive signal P5 is shown as a vector in the third quadrant as described above. However, the first correction circuit 40 receives the drive signal P5, performs phase inversion by the inversion circuit 41, and outputs the drive signal P5. A drive inversion signal P15 having the phase inverted by 180 degrees is output. Thereby, the drive inversion signal P15 can be shown as a vector in the first quadrant as shown.

  The amplitude adjustment circuit 42 of the first correction circuit 40 adjusts the amplitude of the drive inversion signal P15 based on the information of the amplitude adjustment signal P16, and the capacitors C1 and C2 of the first correction circuit 40 have a phase of 90. The first correction signals H1a and H1b that have been advanced are output and added to the detection signals P10a and P10b, respectively. Here, as shown in FIG. 5, since the phases of the first correction signals H1a and H1b are advanced by 90 degrees from the drive inversion signal P15, the second correction signal is inverted by 180 degrees with respect to the phase of the electric leakage signal component L1. It can be shown as a quadrant vector. That is, the electric leakage signal component L1 and the first correction signals H1a and H1b are signals whose phases are inverted by 180 degrees.

  Since the first correction signals H1a and H1b are adjusted in amplitude by the amplitude adjustment circuit 42 as described above, the first correction signals H1a and H1b are adjusted to the same magnitude as the amplitude of the electric leakage signal component L1. I can do it. As a result, the first correction signals H1a and H1b are adjusted to signals having the same amplitude as the phase of the electric leakage signal component L1 inverted by 180 degrees. As a result, when the first correction signals H1a and H1b are added to the detection signals P10a and P10b, the electric leakage signal component L1 generated in the detection signals P10a and P10b can be canceled.

  In other words, the first correction circuit 40 generates the first correction signals H1a and H1b whose phases are inverted by 180 degrees with respect to the electric leakage signal component L1 and whose signal amplitudes are equal to each other. It functions to cancel the signal component L1 accurately. Further, since the first correction circuit 40 generates the first correction signals H1a and H1b based on the drive signal P5 that is the cause of the electric leakage signal component L1, the phase of the drive signal P5 changes. Even so, the phases of the first correction signals H1a and H1b follow the phase of the drive signal P5, and the phase relationship with the electric leakage signal component L1 does not shift. As a result, the electric leakage signal component can be corrected with high accuracy without being affected by changes with time, temperature characteristics, and the like.

  Next, the operation of the second correction circuit 50 that corrects and reduces the machine leakage signal components L2a and L2b will be described with reference to the complex plan views of FIGS. As a premise here, the machine leakage signal component L2a is generated in the detection signal P10a from one detection electrode 5 of the vibrator 1 and is a signal component in phase with the feedback signal P1, and the machine leakage signal component L2b. Is generated in the detection signal P10b from the other detection electrode 6 of the vibrator 1, and is a signal component having a phase opposite to that of the feedback signal P1. Refer to the block diagram of FIG. 1 for the configuration of the vibration type gyro sensor.

  First, based on FIG. 6, the correction of the machine leakage signal component L2a having the same phase with respect to the feedback signal P1 will be described. In FIG. 6, the machine leakage signal component L2a is in phase with the feedback signal P1. On the other hand, the feedback voltage signal P2 has an inverted phase with respect to the feedback signal P1 by the I / V conversion circuit 21. Therefore, the vector of the machine leakage signal component L2a is directed in the opposite direction to the feedback voltage signal P2 as shown in the figure. Here, the second correction signal H2a, which is the output of the amplitude adjustment circuit 51, is added to the detection signal P10a from the detection electrode 5 of the vibrator 1 via the resistor R1.

  Since the second correction signal H2a is in phase with the feedback voltage signal P2 as described above, its vector overlaps with the vector of the feedback voltage signal P2 as shown in FIG. That is, the second correction signal H2a is added to the detection signal P10a as a signal whose phase is inverted with respect to the machine leakage signal component L2a. Further, since the amplitude of the second correction signal H2a is adjusted by the amplitude adjustment circuit 51, the amplitude of the second correction signal H2a can be adjusted to be equal to the amplitude of the machine leakage signal component L2a. As a result, the second correction signal H2a is 180 degrees out of phase with the machine leakage signal component L2a and the amplitude is adjusted to be equal to cancel the machine leakage signal component L2a generated at the detection electrode 5. I can do it.

  Next, correction of the machine leakage signal component L2b having an antiphase with respect to the feedback signal P1 will be described with reference to FIG. In FIG. 7, the machine leakage signal component L2b has an opposite phase to the feedback signal P1. On the other hand, the feedback voltage signal P2 has an inverted phase with respect to the feedback signal P1 by the I / V conversion circuit 21. Therefore, the vector of the machine leakage signal component L2b is in the same direction with respect to the feedback voltage signal P2 as shown in the figure. Here, the second correction inversion signal H2vb, which is the output of the inversion circuit 52, is added to the detection signal P10b from the detection electrode 6 of the vibrator 1 via the resistor R2.

  Since the second corrected inverted signal H2vb is a signal inverted by 180 degrees with respect to the feedback voltage signal P2 by the inverting circuit 52 as described above, its vector is relative to the vector of the feedback signal P1 as shown in FIG. In the opposite direction. That is, the second corrected inverted signal H2vb is added to the detection signal P10b as a signal that is phase-inverted with respect to the mechanical leakage signal component L2b. Further, since the amplitude of the second corrected inverted signal H2vb is adjusted by the amplitude adjustment circuit 51, the amplitude of the second corrected inverted signal H2vb can be adjusted to be equal to the amplitude of the machine leakage signal component L2b. As a result, the second corrected inversion signal H2vb is 180 degrees out of phase with the machine leakage signal component l2b, and the amplitude is adjusted to be equal to cancel the machine leakage signal component L2b generated at the detection electrode 6. I can do it.

  In other words, the second correction circuit 50 generates a second correction signal H2a and a second correction inversion signal H2vb, which are 180 ° phase-inverted with respect to the machine leakage signal components L2a and L2b, respectively, to generate a machine leakage signal. It functions to accurately cancel the components L2a and L2b. The second correction circuit 50 corrects the mechanical leakage signal components L2a and L2b caused by the vibration of the vibrator from the feedback signal P1 having the same phase as the vibration of the vibrator to the second correction signal H2a, Since the second correction inversion signal H2vb is generated, the second correction signal H2a and the second correction inversion signal H2vb follow the change even if the vibration of the vibrator 1 changes with time and temperature characteristics. To do. Therefore, the phase relationship between the machine leakage signal components L2a and L2b does not shift. As a result, the machine leakage signal component can be corrected with high accuracy without being affected by changes over time, temperature characteristics, and the like.

  In addition, the first correction circuit 40 and the second correction circuit 50 of the present invention do not require a phase shifter for fine phase adjustment as in the prior art disclosed in Patent Document 1, and therefore, in the circuit configuration. It is possible to realize a vibration type gyro sensor that has no unstable factors, is not affected by variations in circuit elements, temperature characteristics, and the like and has stable detection characteristics. In addition, since a phase shifter is unnecessary, a vibration type gyro sensor with a small circuit scale and low cost can be provided.

  As a premise for explaining the operation of the second correction circuit 50, the machine leakage signal component L2a is a signal component in phase with the feedback signal P1 generated from one detection electrode 5 of the vibrator 1, and the machine The signal component L2b is a signal component having a phase opposite to that of the feedback signal P1 generated from the other detection electrode 6 of the vibrator 1, but the phase of the mechanical leakage signal components L2a and L2b is limited to this assumption. Not. That is, the phase of the mechanical leakage signal components L2a and L2b is caused by the mass balance deviation of the vibrator 1, and the phase relationship between the mechanical leakage signal components L2a and L2b is inverted depending on the balance state. In some cases, the machine leakage signal component L2a has the opposite phase to the feedback signal P1, and the machine leakage signal component L2b has the same phase to the feedback signal P1.

  And when the phase of the mechanical leak signal components L2a and L2b is inverted in this way, the two correction signals may be exchanged and connected to the detection electrodes 5 and 6 of the vibrator 1. That is, if the second correction signal H2a from the resistor R1 is connected to the detection electrode 6 of the vibrator 1 and the second correction inverted signal H2vb from the resistor R2 is connected to the detection electrode 5 of the vibrator 1, the machine Since the inverted correction signals can be added to the leak signal components L2a and L2b, respectively, the machine leak signal components L2a and L2b can be canceled in the same manner.

  Also, when the mass balance of the vibrator 1 changes due to manufacturing variations of the vibrator, and it is unclear whether the second correction signal H2a or the second correction inversion signal H2vb should be connected to the detection electrodes 5 or 6. As an example of a countermeasure, there is a method for preliminarily damaging the vibration of the vibrator 1 by intentionally generating a mechanical leak, for example, by making the cross-sectional shape of the driving branch of the vibrator 1 asymmetric. is there. If such a method is taken, the phase of the machine leakage signal component generated at the two detection electrodes 5 and 6 is limited, so that the phase is determined based on the phase of the limited machine leakage signal component. The second correction circuit 50 may be configured to connect the inverted correction signal.

  The first embodiment of the present invention is a vibration type gyro sensor that is suitable when the phase of the mechanical leakage signal component is limited by adding vibration to the vibration of the vibrator as described above. In this way, by adding vibration to the vibrator 1, the second correction circuit 50 according to the first embodiment is simplified, and there is an advantage that adjustment work for correction can be simplified.

  Next, the correction adjustment work of the vibration type gyro sensor of the present invention will be described based on the flowchart of FIG. Refer to FIG. 1 for the configuration of the vibration type gyro sensor. As a premise for explanation, it is assumed that an external control device (not shown) for controlling correction adjustment is connected to the outside of the vibration type gyro sensor to perform correction adjustment work.

  In FIG. 8, first, power is supplied to the vibration gyro sensor of the present invention without applying an angular velocity by the external control device, and the vibration gyro sensor starts operating (step ST1). As a result, the vibrator 1 of the vibration type gyro sensor starts to oscillate. Here, since no angular velocity is applied to the vibration type gyro sensor, no component due to the angular velocity is generated in the detection signals P10a and P10b, but the electric leakage signal component L1 and the mechanical signal are detected from the detection electrodes 5 and 6 of the vibrator 1. Leakage signal components L2a and L2b are generated.

  Next, the external control device controls the first and second correction circuits to set the output levels of the first correction signal H1 and the second correction signal H2 to zero, and then from the monitor terminal 12 of the vibration type gyro sensor. Then, the detection voltage P11a is input as a monitor signal, the electric leakage signal component L1 advanced by 90 degrees from the drive signal P5 is detected, and the magnitude thereof is measured (step ST2). The monitor signal may be the detection voltage P11b.

  Next, the external control device generates control data for controlling the amplitude adjustment circuit 42 of the first correction circuit 40 based on the measured magnitude of the electric leakage signal component L1, and the I / O of the vibration type gyro sensor. Control data is transferred from the F terminal 13 to the control circuit 11 (step ST3). As a result, the control circuit 11 of the vibration type gyro sensor outputs the amplitude adjustment signal P16 based on the received control data, and the amplitude adjustment circuit 42 adjusts the amplitude of the first correction signal H1 by the amplitude adjustment signal P16. adjust.

  Next, the external control device again detects the electric leakage signal component L1 from the monitor terminal 12, measures its magnitude, and determines whether the leakage component is equal to or less than a predetermined value (step ST4). If the determination is affirmative (the leakage component is equal to or less than the predetermined value), the process proceeds to the next step. If the determination is negative (greater than the predetermined value), the process returns to step ST3 to update the control data. Steps ST3 and ST4 are repeatedly executed until the predetermined value or less is reached.

  Next, if an affirmative determination is made in step ST4, the external control device inputs the detection voltage P11a again from the monitor terminal 12 of the vibration type gyro sensor, detects the mechanical leakage signal component L2a, and determines the magnitude thereof. Measure (step ST5).

Since the next step ST6 is the operation in the second embodiment, it is skipped in the first embodiment.

  Next, the external control device generates control data for controlling the amplitude adjustment circuit 51 of the second correction circuit 50 based on the magnitude of the measured machine leakage signal component, and the I / F of the vibration type gyro sensor. Control data is transferred from the terminal 13 to the control circuit 11 (step ST7). Thereby, the control circuit 11 of the vibration type gyro sensor outputs the amplitude adjustment signal P17 based on the received control data, and the amplitude adjustment circuit 51 adjusts the amplitude of the second correction signal H2 by the amplitude adjustment signal P17. adjust. In measuring the magnitude of the mechanical leakage signal component, the differential output P12 may be used as a monitor instead of the detection voltage P11a.

  Next, the external control device again detects the machine leakage signal component from the monitor terminal 12, measures its magnitude, and determines whether the leakage component is equal to or less than a predetermined value (step ST8). If the determination is affirmative (the leakage component is equal to or less than the predetermined value), the process proceeds to the next step. If the determination is negative (greater than the predetermined value), the process returns to step ST7 to update the control data. Steps ST7 and ST8 are repeatedly executed until the value becomes equal to or less than the predetermined value.

  Next, if an affirmative determination is made in step ST8, the external control device sends a write control signal to the I / F terminal 13 of the vibration type gyro sensor, and the control data of the first correction circuit 40 and the second correction circuit. 50 control data is stored in the non-volatile memory built in the control circuit 11, and the correction adjustment work is terminated (step ST9). Through the above adjustment work, the vibration type gyro sensor of the present invention is individually adjusted so that the electric leakage signal component and the mechanical leakage signal component are minimized, and shipped as a product. Note that the above-described correction and adjustment work of the vibration type gyro sensor may be performed manually using a measurement device, a data input device, or the like without using an external control device.

  Next, the configuration of the vibration type gyro sensor according to the second embodiment of the present invention will be described with reference to FIG. A feature of the second embodiment is a vibration type gyro sensor suitable for a case where the vibration of the vibrator is not obscured and the phase of the mechanical leakage signal component is not determined due to manufacturing variations of the vibrator. The configuration of the second embodiment is different from the first embodiment only in the second correction circuit 50 and the control circuit 11, and therefore the same elements are denoted by the same reference numerals and the description of the second embodiment. Is limited to the configuration and operation of different locations.

  In FIG. 9, the second correction circuit 50 includes an amplitude adjustment circuit 51, an inverting circuit 52, a switching circuit 53, and resistors R1 and R2 as two resistance elements. Here, since the amplitude adjustment circuit 51 and the inverting circuit 52 are the same as those in the first embodiment, the description thereof is omitted. The switching circuit 53 inputs the second correction signal H2 that is a non-inverted signal and the second correction inverted signal H2v that is an inverted signal, and the switching operation A and the switching operation B according to the switching control signal P18 from the control circuit 11. Is selected and switched between the second correction signal H2 and the second correction inversion signal H2v and connected to the resistors R1 and R2.

  Here, in the switching operation A, the second correction signal H2 is connected to the resistor R1, and the second correction inverted signal H2v is connected to the resistor R2. This switching operation A is the same connection as that of the second correction circuit 50 of the first embodiment, and the detection signal P10a from the detection electrode 5 of the vibrator 1 has a mechanical leakage signal component L2a in phase with the feedback signal P1. This is selected when a machine leakage signal component L2b having a phase opposite to that of the feedback signal P1 is generated in the detection signal P10b from the detection electrode 6 of the vibrator 1.

In the switching operation B, the second correction signal H2 is connected to the resistor R2, and the second correction inverted signal H2v is connected to the resistor R1. In this switching operation B, a mechanical leakage signal component L2b having the same phase as that of the feedback signal P1 is generated in the detection signal P10a from the detection electrode 5 of the vibrator 1, and the detection signal P10b from the detection electrode 6 of the vibrator 1 is generated. This is selected when a machine leakage signal component L2a having a phase opposite to that of the feedback signal P1 is generated.

  Next, the correction adjustment operation of the vibration type gyro sensor according to the second embodiment of the present invention will be described with reference to the flowchart of FIG. In addition, since the correction adjustment work of Example 2 only adds step ST6 with respect to the flowchart of Example 1, only step ST6 is demonstrated.

  In FIG. 8, if the external control device (not shown) detects a leakage signal component that is the difference between the machine leakage signal components L2a and L2b in step ST5, the phase of the machine leakage signal component of the difference is detected. Then, it is determined whether the feedback signal P1 has the same phase or the opposite phase, and a control signal is sent to the control circuit 11 via the I / F terminal 13 and switched by the switching control signal P18 from the control circuit 11. The circuit 53 is controlled to select the switching operation A or the switching operation B (step ST6).

  Thereby, even if the phase relationship between the machine leakage signal components L2a and L2b generated in the detection signals P10a and P10b from the detection electrodes 5 and 6 of the vibrator 1 is inverted with respect to the feedback signal P1, the machine leakage signal is detected. The second correction signal H2a and the second correction inversion signal L2vb can be switched and added so as to cancel the components L2a and L2b. As a result, the vibration signal component is minimal for any vibrator, such as when the vibration of the vibrator is not obscured and the phase of the machine leakage signal component is not determined due to manufacturing variations of the vibrator. It can be corrected so that

  In addition, although resistance R1, R2 of the 2nd correction circuit 50 was shown as fixed resistance in Example 1 and Example 2, in order to expand the adjustment range of a machine leak signal component, it is not limited to this, A variable resistor that can be switched to a plurality of resistance values may be used. Further, the control IC 10 is preferably configured by a single chip, but is not limited to this, and may be configured as a multi-chip.

  As described above, the vibration type gyro sensor according to the present invention corrects the electric leakage signal component generated by the drive signal P5 with the correction signal generated from the drive signal P5, and is a machine generated by the vibration of the vibrator. The leakage signal component is corrected by a correction signal generated from the feedback signal P1. As a result, each leakage signal component is individually corrected, so that both the electric leakage signal component and the mechanical leakage signal component can be corrected to be minimum. In addition, even if the phase of the electrical leakage signal component and the mechanical leakage signal component changes, a correction signal can be generated and corrected following the phase, so it is necessary to adjust the phase using a phase shifter or the like. No.

  As a result, it is possible to provide a vibration type gyro sensor capable of stably detecting an angular velocity with high accuracy without being affected by variations in circuit elements, changes with time, temperature characteristics, and the like. The block diagrams and flowcharts shown in the embodiments of the present invention are not limited to this, and may be arbitrarily changed as long as they satisfy the gist of the present invention.

It is a block diagram which shows schematic structure of the vibration type gyro sensor of Example 1 of this invention. It is a perspective view of a vibrator of a vibration type gyro sensor of the present invention. It is sectional drawing which shows the electrode structure of the vibrator | oscillator of the vibration type gyro sensor of this invention. It is a complex plan view showing the relationship between the drive signal and the electric leakage signal component and the relationship between the feedback signal and the mechanical leakage signal component of the vibration type gyro sensor of the present invention. It is a complex top view explaining operation | movement of the 1st correction | amendment circuit of the vibration type gyro sensor of this invention. FIG. 10 is a complex plan view for explaining an operation of correcting a mechanical leakage signal component having an antiphase with respect to a feedback signal of a second correction circuit of the vibration type gyro sensor of the present invention. FIG. 9 is a complex plan view for explaining a correction operation of a mechanical leakage signal component in phase with respect to a feedback signal of a second correction circuit of the vibration gyro sensor of the present invention. It is a flowchart explaining the correction | amendment adjustment work of the vibration type gyro sensor of this invention. It is a block diagram which shows schematic structure of the vibration type gyro sensor of Example 2 of this invention. It is a block diagram of the angular velocity sensor which detects the conventional angular velocity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibrator 2a, 2b Drive branch 2c Detection branch 3, 4 Drive electrode 5, 6 Detection electrode 8 Base 9 Support part 10 Control IC
DESCRIPTION OF SYMBOLS 11 Control circuit 12 Monitor terminal 13 I / F terminal 20 Oscillation circuit 21 I / V conversion circuit 22 Phase shift circuit 23 Amplitude detection circuit 24 Gain variable amplification circuit 30 Detection circuit 31, 32 Displacement detection circuit 33 Differential amplifier 34 Synchronous detection circuit 35 Amplifier circuit 36 Low pass filter (LPF)
41, 52 Inversion circuit 42, 51 Amplitude adjustment circuit 53 Switching circuit C1, C2 Capacitor R1, R2 Resistance P1 Feedback signal P2 Feedback voltage signal P3 Phase shift signal P4 AGC signal P5 Drive signal P10a, P10b Detection signal P11a, P11b Detection voltage P12 Differential output P13 Detection output P15 Drive inversion signal P16, P17 Amplitude adjustment signal P18 Switching control signal Po Angular velocity output H1, H1a, H1b First correction signal H2, H2a Second correction signal H2v, H2vb Second correction inversion signal L1 Electric leakage signal component L2a, L2b Mechanical leakage signal component

Claims (6)

An oscillator, and an oscillation circuit that applies a drive signal to the oscillator and receives a feedback signal from the oscillator, and oscillates the oscillator.
In the vibration-type gyro sensor in which the vibrator outputs a detection signal corresponding to the applied angular velocity,
A first correction circuit for correcting an electric leakage signal component of the detection signal based on the drive signal;
A vibration type gyro sensor, comprising: a second correction circuit that corrects a mechanical leak signal component of the detection signal based on the feedback signal. The vibration type gyro sensor according to claim 1, wherein the first correction circuit includes an amplitude adjustment circuit, an inverting circuit, and a capacitive element. The vibrator outputs a first detection signal and a second detection signal,
The second correction circuit includes an amplitude adjustment circuit and an inverting circuit, and corrects the first detection signal with one of a signal inverted by the inverting circuit and a non-inverted signal, The vibration type gyro sensor according to claim 1, wherein the second detection signal is corrected by a signal of The vibration type gyro sensor according to claim 3, wherein the second correction circuit includes a switching circuit that switches between a signal inverted by the inverting circuit and a non-inverted signal. 5. The vibration gyro sensor according to claim 2, further comprising: a control circuit that controls an amplitude adjustment amount by the amplitude adjustment circuit. The vibration type gyro sensor according to claim 4, further comprising a control circuit that controls the switching circuit.

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