JPS63241308A - Angular velocity sensor - Google Patents

Abstract

PURPOSE:To obtain a detection signal having good accuracy, by inputting the output signals from two detection electrodes of a detection element to a subtractor through a phase shifter and a voltage divider and outputting a detection signal of angular velocity on the basis of the output of the subtractor. CONSTITUTION:The output terminal 16 of a detection element 23 is earthed and the output signals from output terminals 19, 20 are supplied to phase shifters 24, 25. The output signals of the phase shifters 24, 25 are respectively supplied to voltage dividers 26, 27 while the output signals of the voltage dividers 26, 27 are supplied to a subtractor 28. When angular velocity vector OMEGA is generated, the AC voltages different in a phase from each other corresponding to Coriolis force are generated at the output terminals 19, 20 of the detection element 23. As a result, the output signal level of the subtractor 28 generates the change corresponding to the angular velocity vector OMEGA. By this method, the effect of a drive signal is eliminated and accurate detection can be performed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an angular velocity sensor that is installed on a rotating body and detects its angular velocity. Regarding circuits.

[Conventional technology]

In recent years, there has been an increasing demand for angular velocity sensors that detect the angular velocity of rotating bodies in fields such as automobiles and self-propelled robots. Among them, the vibrating type is attracting attention because of its advantages such as light weight, long life, low hysteresis, and low power consumption.

This angular velocity sensor is described in Nisnee Technical Paper Series 830727 (1985
, 4, 12-15), “Solid State Sensor Technology and Applications J [1 (tchard U, Ayre
s: Sol td -5tate 5ensor
Technology and Appl 1cati
ons, SAE Tehnical Paper
5eries, 830727. April 12-1
51983] is introduced in the literature entitled t,★. Among these vibration type angular velocity sensors, the
The device described in Japanese Patent No. 8-174854 combines two piezoelectric elements, one for detection and the other for drive, to form a pair, and uses two such pairs of piezoelectric elements. A protruding element is formed in the shape of a tuning fork, and this element is rotated together with the rotating body to be measured, and the driving piezoelectric elements are arranged with the same amplitude, the same periodic mantissa, and a phase of 1.
A Coriolis force is generated on each detection piezoelectric element by vibrating at a difference of 80 degrees, and the sum of these Coriolis forces #: (
710m), and the angular velocity of the rotating body included therein is detected by electrical processing. By configuring the detection element in this way, linear vibrations and accelerations can be detected! I! The influence of low motion generated by the piezoelectric element for A motion is almost eliminated, and the angular velocity is detected with high accuracy. An example of the processing circuit of the angular velocity sensor described in this Japanese Patent Application Laid-open No. 58-174854 is based on sensor technology. Edit ff [
! Information Research Association Mitsuyuki: Sensor Device Handbook (19
83, 11, 15) PP, 193-194 As shown in the section KM of "49. Angular velocity sensor", a drive circuit that supplies a constant width and -i number of rotations to a driving piezoelectric element (base crystal) A self-help oscillation circuit including an automatic gain control circuit and a compensation capacitor is described as a self-help oscillation circuit, and a charge amplifier and a bandpass filter are also used as a detection circuit to detect an angular velocity signal from a Senzoku output pressure FIL element (sense crystal). A demodulator including a synchronous detection circuit is described.

In this prior art, the influence of the drive generated by the drive piezoelectric element is removed by wiring (connection) between the electrodes of the two detection piezoelectric elements.

[Problem that the invention seeks to solve]

In the above-mentioned conventional temporary technique, the two detection rolling elements'w
Since the wiring (connection) between the L poles was used to remove the influence of vibration generated by the driving piezoelectric element, the influence still remained. That is, even though the detection element was not rotating, an alternating current voltage was generated between the electrodes of the detection pressure 1J7.

The reason for this is due to variations in the four pressure section elements.
This is because the phase of the alternating current voltage generated in the two detection piezoelectric elements is not the same as that of the positive voltage. Furthermore, no consideration was given to the fact that the combination of alternating current voltages with different amplitudes and phases results in alternating current voltages with even different amplitudes and phases, which increases the detection error of the Coriolis force.

An object of the present invention is to solve the problems of the conventional angular velocity sensor described above, eliminate the influence of vibration generated by the IjA dynamic piezoelectric element, and provide an angular velocity sensor that can output detection with high accuracy. It is to be.

[+ Settings to solve problems]

In order to achieve the above object, the present invention inputs output signals (AC current EE) from two detection poles of the detection element 0 to a subtracter via a phase shifter and a voltage divider, respectively, and outputs a signal from the subtractor. Based on this, angular velocity detection No. 1B is output.

[Effect]

2 signals with different phases and amplitudes from the two detection 'FIL poles.
The two outputs No. 18 are each adjusted to the same phase by a phase shifter and output. Then, they are each adjusted to the same amplitude by a voltage divider and output. Since the X-reducer subtracts the two signals of the same phase and the same amplitude via the phase shifter and voltage divider, the influence of the drive signal is eliminated, and the Coriolis force detection signal is output with high accuracy.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a plan view of a detection element used in one embodiment of the present invention, in which 1 is a piezoelectric substrate, and drive electrodes 2° 3 and 62 in the surface acoustic wave generation phase are disposed on the surface of the piezoelectric substrate 10. .65
Or they are arranged in pairs in a comb shape. The arrangement is such that the surface acoustic waves generated by drive electrodes 2.3 and 62.63 are in phase. A grating 6.7 that reflects surface acoustic waves generated from the drive electrodes 2.3 and 62, 63 is provided in a blind shape on the outside of the drive wJt poles 2.3 and 62.65, respectively.
Further, the piezoelectric substrate 1fzr: detection electrodes 4 and 5 are comb-shaped and can detect the Coriolis force generated in the elastic vibrating portion due to surface acoustic waves when rotated at the angular velocity vector 18. Furthermore, an intermediate electrode 37 is provided at the center of the surface of the piezoelectric substrate 1, and is connected to a ground 15 via a terminal 14.
and is connected to the output terminal 16. Also,
The drive electrode 2 is grounded 15' via the terminal 8 and connected to the input terminal 13. The drive electrode 62 is grounded 151 via a terminal 64. The drive electrodes 3.63 are each connected to the input terminal 12 via a terminal 9.65. The detection '#IL pole 4 is connected to the output terminal 19 via the terminal 10, and the detection electrode 5 is connected to the output terminal 20 via the terminal 11.

The operation of the detection element configured in this way will be explained below.

Input terminal 12. When applying cross R1IIL pressure between L5,
The surface acoustic wave generated by the drive electrode 2.6 travels to the intermediate electrode 671j111 once the grating 6 is present. Further, since the grating 7 is present, the surface acoustic waves generated by the drive electrodes 62' and 65 similarly advance to the intermediate electrode 371111. As a result, the amplitudes of both surface acoustic waves are multiplied by 7JO, and vibration is generated in the center of the intermediate electrode 67 in a direction perpendicular to the plane of the drawing. Then, due to this following motion, an AC voltage is generated between the extraction kL pole 4 and the intermediate electrode 37, and an AC voltage is also generated between the detection electrode 5 and the intermediate electrode 37. This alternating voltage has a slightly different phase and amplitude due to errors in electrode deposition. In this state, if the angular velocity guktor occurs for 1 day, then the intermediate 1
Due to the vibration perpendicular to the paper surface generated at the 1L pole 37,
Coriolis force is generated. Due to this Coriolis force,
When a compressive strain occurs between the detection electrode 4 and the intermediate electrode 57, an extensional strain occurs between the detection electrode 5 and the intermediate electrode 37. Therefore, alternating current voltages having substantially opposite phases to each other are generated in the structure area poles 4 and 5 in accordance with the Coriolis force. These AC voltages are output between output terminals 16.19 and 16.20.

Next, one embodiment of the present invention will be explained with reference to the block diagram of FIG. The output signal of the party transfer 21 is sent to the high frequency transformer 22
via the detection element 260 input terminal 12 described in FIG.
．． 15. Here, 2 of the high frequency transformer 22
The next side is set to cause parallel resonance with the input capacitance of the detection element 230, etc.

The output terminal 16 of the detection element 23 is grounded, and the output terminal 19
．． The output signal from 20 is fed to phase shifter 24.251c. Here, at a time point when no angular velocity vector stem is generated, the phase shifter 24 is configured to cause parallel resonance with each award between the output terminals 19 and 16. Further, the phase shifter 25 resonates in parallel with the capacitance t of the output terminal 175.20.

It is set near the frequency, and the output terminal 191
! The output signal of ll and the output signal of the output terminal 20 are set to be in phase. The output signals of the phase shifter 2425 are supplied to voltage dividers 26 and 27, respectively. Here, if the amplitude of the output signal of the phase shifter 24 is larger than the amplitude of the output 1♂° of the phase shifter 25, the voltage divider 27 is set to perform the minimum voltage division. The voltage generator 26 is set so that its output signal has the same amplitude as the output signal of the voltage divider 27.

Therefore, at the time when the angular velocity vector is not generated, the output signals of the voltage dividers 26 and 27 are AC voltages having the same phase and the same amplitude. The output of this voltage divider 26,27 is
The signal is supplied to a dX unit 28. The subtracter 28 is a voltage divider 26
．． The two signals supplied from 27 are subtracted and the output i signal is supplied to the synchronous detector 31.

Naturally, the level of the output signal of the subtracter 28 is O at the time when the angular velocity vector support is not occurring. Then, when the angular velocity vector support occurs, as described in FIG. 2, AC' voltages having opposite phases to each other according to the Coriolis force are generated at the output terminals 19 and 20 of the detection element 26. As a result, the output signal level of the reducer/Xer 28 changes in accordance with the angular velocity Ω.

On the other hand, the input signal of the detection element 230 is supplied to the phase shifter 30K via the buffer 29. The phase shifter 30 converts the supplied signal into a required phase and supplies it to the synchronous detector 31. The arithmetic detector 31 is composed of an analog multiplier and a low-pass filter type differential amplifier, and after multiplying the signal from the phase shifter 30 and the signal from the subtracter 28, amplifies the low frequency component and calculates the magnitude of the angular velocity vector Ω. Outputs a scratch number according to the direction.

〔Effect of the invention〕

As explained above, according to the present invention, two of the detection elements
The output signals from the two detection electrodes are input to the JL subtractor via the phase shifter and voltage divider, and the angular velocity detection signal is output based on the output signal of the subtractor, eliminating the influence of the drive signal. , which enables good detection of tree cover. Also,
The phase shifter described above has the effect of outputting a large detection voltage because it combines the capacitance of the detection electrode portion and the like of the parallel resonant circuit.

Although an embodiment using a surface acoustic wave element as a detection element has been shown, the present invention is also effective in the type of element described in the conventional example.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a flat curved diagram showing the projecting element used in FIG. 21... Genjiki, 23... Detection element, 24.25.
... Phase shifter, 26, 27... minute If gain, 28... decrease J/4. 30... Phase shifter, 61... Same M wave inertia.

Claims (1)

[Claims] 1. In order to prevent the detection signal from being affected by vibrations generated by the drive signal, two or two pairs of detection electrodes are provided,
In a device configured to mutually compensate the output signals from these detection electrodes, a phase shifter is used to make the two output signals in phase with each other when no angular velocity is generated, and a phase shifter is used to make the two output signals the same amplitude. An angular velocity sensor comprising: a pressure regulator; and a subtracter for subtracting the output signal via the phase shifter and the voltage divider.