JP5034624B2 - Angular velocity sensor - Google Patents

Description

  The present invention relates to sensors used in various electronic devices such as attitude control and navigation of moving bodies such as aircraft, automobiles, robots, ships, and vehicles.

  Hereinafter, a conventional angular velocity sensor will be described.

  FIG. 6 is a circuit block diagram of a conventional angular velocity sensor.

  In FIG. 6, the conventional angular velocity sensor includes a vibrator 1 having a drive electrode 2, a monitor electrode 3, and a detection electrode 4, a drive circuit 5 connected to the drive electrode 2 of the vibrator 1, and a detection electrode of the vibrator 1. 4, a detection amplification circuit 6 connected to the monitor electrode 3 of the vibrator 1, a vibration control circuit 8 connected between the monitor amplification circuit 7 and the drive circuit 5, and a detection amplification circuit 6. Is detected by the output signal of the monitor amplifier circuit 7. The monitor amplifier circuit 7 includes a first amplifier 10, a first feedback resistor 11, and a first feedback capacitor 12. The detection amplifier circuit 6 includes a second amplifier 13, a second feedback resistor 14, and a second feedback capacitor 15.

  Further, as shown in FIG. 7, the vibrator 1 includes a vibrator substrate 16, a reference electrode 17 disposed on the vibrator substrate 16, a piezoelectric layer 18 disposed on an upper layer of the reference electrode 17, and an upper layer of the piezoelectric layer 18. The drive electrode 2, the monitor electrode 3, and the detection electrode 4 are arranged.

  At this time, the relative dielectric constant ε, the electrode area S, and the inter-electrode distance d of the piezoelectric layer 18 are between the reference electrode 17 that is the lower electrode and the drive electrode 2, the monitor electrode 3, and the detection electrode 4 that are the upper electrodes. given that,

Are formed, a drive electrode capacity 19, a monitor electrode capacity 20, and a detection electrode capacity 21 are formed.

  The monitor electrode capacitance 20 and the detection electrode capacitance 21 are input load capacitances of the monitor amplification circuit 7 and the detection amplification circuit 6, respectively. As shown in FIG. 8, the gain peak frequency fp of the amplifier caused by this input load capacitance is expressed by the following equation, where CL is the input load capacitance, fu is the band frequency of the amplifier, and Rf is the feedback resistance of the amplifier.

  In order to flatten the gain peak due to this input load capacity,

Is required to be connected in parallel to the feedback resistor Rf.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2002-267448 A

  In the above conventional configuration, even if the bandwidth frequency fu and the feedback resistance of the amplifier used in the monitor amplifier circuit and the detection amplifier circuit are the same, the input load of the capacitance value of the monitor electrode and the capacitance value of the detection electrode Due to the difference in capacitance value CL, the peak frequency fp of the monitor amplifier circuit and the detection amplifier circuit are also different, and the feedback capacitance Cf of the monitor amplifier circuit and the detection amplifier circuit is set to different values to attenuate the peak frequency fp. Need arises.

  As a result, as shown in FIG. 9, the monitor amplification signal output from the monitor amplification circuit and the detection amplification signal output from the detection amplification circuit cause a phase shift, and the output of the synchronous detection circuit is output according to this phase difference Φ. In this case, an unnecessary offset signal is generated and the angular velocity is detected as an error.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an angular velocity sensor that solves the above-described problems and prevents the monitor amplification signal and the detection amplification signal from being out of phase with each other.

In order to achieve the above object, the present invention particularly relates to a vibrator having a drive electrode, a monitor electrode, and a detection electrode, a drive circuit for supplying a drive signal to the drive electrode to vibrate the vibrator, and an inertial force. Due to this, a detection signal amplification circuit that amplifies the detection signal output from the detection electrode, a monitor signal amplification circuit that amplifies the monitor signal output from the monitor electrode, and the monitor that is output from the monitor signal amplification circuit A vibration control circuit that controls an energization amount of the drive signal with reference to the amplified signal; and a synchronous detection circuit that detects the detected amplified signal with reference to the monitor amplified signal. An amplifier, a first feedback resistor, and a first feedback capacitor; and the detection signal amplifier circuit has a second amplifier, a second feedback resistor, and a second feedback capacitor, and is generated by the monitor electrode. Was equal to the capacitance value generated in an amount value and the detection electrode, before SL and equal to the second feedback resistor and the first feedback resistor, equal to the second feedback capacitor between the first feedback capacitor This is the configuration.

  With the above configuration, since the capacitance value generated at the monitor electrode and the capacitance value generated at the detection electrode are equal, the peak frequencies of the monitor amplification circuit and the detection amplification circuit are also equal, and the monitor amplification circuit The peak frequency can be attenuated by adjusting the first and second feedback capacitors of the detection amplifier circuit with the same value. That is, the monitor amplification signal output from the monitor amplification circuit and the detection amplification signal output from the detection amplification circuit can suppress the phase shift, the output offset signal of the synchronous detection circuit due to the phase difference Φ is also suppressed, and the angular velocity Error detection can be suppressed.

  In particular, if the components of the first amplifier and the second amplifier are made equal, the first feedback resistor and the second feedback resistor are made equal, and the first feedback capacitor and the second feedback capacitor are made equal, the monitor amplification The monitor amplification signal output from the circuit and the detection amplification signal output from the detection amplifier circuit can further suppress the phase shift, and the above effect can be obtained.

  FIG. 1 is a block diagram of an angular velocity sensor according to an embodiment of the present invention.

  In FIG. 1, an angular velocity sensor according to an embodiment of the present invention includes a vibrator 31 having a drive electrode 32, a monitor electrode 33, and a detection electrode 34, and energizes the drive electrode 32 with a drive signal to vibrate the vibrator 31. A drive circuit 35; a detection signal amplification circuit 36 that amplifies a detection signal output from the detection electrode 34 due to inertial force; a monitor signal amplification circuit 37 that amplifies the monitor signal output from the monitor electrode 33; A vibration control circuit 38 that controls the energization amount of the drive signal with reference to the monitor amplification signal output from the signal amplification circuit 37, a synchronous detection circuit 39 that detects the detection amplification signal with reference to the monitor amplification signal, and vibration control An attenuation circuit 49 for attenuating the amplitude value of the monitor amplification signal is provided in the previous stage of the circuit 38.

  The monitor signal amplifier circuit 37 includes a first amplifier 40, a first feedback resistor 41, and a first feedback capacitor 42. The detection signal amplifier circuit 36 includes a second amplifier 43, a second feedback resistor 44, and a second feedback capacitor. 45.

  Further, by making the electrode area of the monitor electrode 33 and the electrode area of the detection electrode 34 equal, the capacitance value generated by the monitor electrode 33 and the capacitance value generated by the detection electrode 34 are made equal. ing.

  Further, the constituent elements of the first amplifier 40 and the constituent elements of the second amplifier 43 are made equal, the first feedback resistor 41 and the second feedback resistor 44 are made equal, and the first feedback capacitor 42 and the second feedback capacitor 45 are connected. Are equal.

  As shown in FIG. 2, the vibrator 31 is disposed on the substrate 46, the reference electrode 47 disposed on the substrate 46, the piezoelectric layer 48 disposed on the reference electrode 47, and the piezoelectric layer 48. Drive electrode 32, monitor electrode 33, and detection electrode 34.

  With the above configuration, since the capacitance value generated by the monitor electrode 33 and the capacitance value generated by the detection electrode 34 are equal, each of the monitor amplification circuit 37 and the detection amplification circuit 36 is shown in FIG. As shown in FIG. 4, the first and second feedback capacitors 42 and 45 of the monitor amplifier circuit 37 and the detection amplifier circuit 36 are adjusted to the same value to attenuate the peak frequency, as shown in FIG. it can.

  That is, as shown in FIG. 5, the phase shift between the monitor amplification signal output from the monitor amplification circuit 37 and the detection amplification signal output from the detection amplification circuit 36 can be suppressed, and the synchronous detection circuit 39 caused by the phase difference Φ can be suppressed. The output offset signal can also be suppressed, and angular velocity error detection can be suppressed.

  In particular, the constituent elements of the first amplifier 40 and the constituent elements of the second amplifier 43 are made equal, the first feedback resistor 41 and the second feedback resistor 44 are made equal, and the first feedback capacitor 42 and the second feedback capacitor 45 are made. If they are equal, the monitor amplification signal output from the monitor amplification circuit 37 and the detection amplification signal output from the detection amplification circuit 36 can further suppress the phase shift, and the above effect can be obtained.

  Further, by making the electrode area of the monitor electrode 33 and the electrode area of the detection electrode 34 equal, the capacitance value generated by the monitor electrode 33 and the capacitance value generated by the detection electrode 34 can be easily equalized. it can.

  Furthermore, since the attenuation circuit 49 for attenuating the amplitude value of the monitor amplification signal is provided in the previous stage of the vibration control circuit 38, the vibration control circuit 38 can appropriately control the amplitude value of the drive signal energized to the drive electrode 32. . That is, when the monitor amplification signal is input to the vibration control circuit 38 as it is, the monitor signal is amplified by the monitor amplification circuit 37, so that it is erroneously recognized that the driving state of the vibrator 31 vibrates more than necessary. There is a possibility that a drive signal having a small amplitude value attenuated by the vibration control circuit 38 may be input to the drive electrode 32. When the gain of the detection amplifier circuit 36 is simply increased, the gain of the monitor amplifier circuit 37 is also increased in conjunction with it, and it is erroneously recognized that the driving state of the vibrator 31 is vibrated more than necessary.

  However, since the monitor amplification signal is attenuated by the attenuation circuit 49 with the above configuration, the gain on the detection side can be increased, and an appropriately controlled drive signal can be generated on the drive side. A drive signal can be input to the drive electrode 32. The degree of attenuation of the drive amplification signal may be attenuated to the same level as the monitor signal.

  Since the angular velocity sensor according to the present invention can improve detection sensitivity, it can be applied to various electronic devices.

The block diagram of the angular velocity sensor in one embodiment of this invention AA sectional view of FIG. Gain frequency characteristics of amplifier before attenuation of peak frequency Gain frequency characteristic diagram of amplifier after attenuation of peak frequency Characteristic diagram showing synchronous detection signal and angular velocity signal processed by it Block diagram of a conventional angular velocity sensor AA sectional view of FIG. Gain frequency characteristics of amplifier before attenuation of peak frequency Characteristic diagram showing synchronous detection signal and angular velocity signal processed by it

Explanation of symbols

32 drive electrode 33 monitor electrode 34 detection electrode 35 drive circuit 36 detection signal amplification circuit 37 monitor signal amplification circuit 38 vibration control circuit 39 synchronous detection circuit 40 first amplifier 41 first feedback resistor 42 first feedback capacitor 43 second amplifier 44 second 2 feedback resistor 45 second feedback capacitance 46 substrate 47 reference electrode 48 piezoelectric layer 49 attenuation circuit

Claims (4)

A vibrator having a drive electrode, a monitor electrode, and a detection electrode; a drive circuit for passing a drive signal through the drive electrode to vibrate the vibrator; and a detection signal output from the detection electrode due to inertial force. A detection signal amplification circuit for amplifying, a monitor signal amplification circuit for amplifying a monitor signal output from the monitor electrode, and an energization amount of the drive signal based on the monitor amplification signal output from the monitor signal amplification circuit A vibration control circuit for controlling, and a synchronous detection circuit for detecting the detection amplification signal on the basis of the monitor amplification signal,
The monitor signal amplifier circuit includes a first amplifier, a first feedback resistor, and a first feedback capacitor, and the detection signal amplifier circuit includes a second amplifier, a second feedback resistor, and a second feedback capacitor, a capacitance value generated by the electrostatic capacitance value and the detection electrode that is generated at the electrode equal the previous SL first and feedback resistor equal to the second feedback resistor, the said first feedback capacitor An angular velocity sensor having the same second feedback capacity. The angular velocity sensor according to claim 1, wherein an electrode area of the monitor electrode is equal to an electrode area of the detection electrode. The angular velocity sensor according to claim 1, wherein an attenuation circuit for attenuating an amplitude value of the monitor amplification signal is provided before the vibration control circuit. The angular velocity sensor according to claim 1, wherein the constituent elements of the first amplifier and the constituent elements of the second amplifier are made equal.

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