JPH0814916A - Vibration gyro detection circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a vibration gyro detection circuit capable of removing null waves with high accuracy even when the temperature changes and effectively suppressing drift due to temperature or the like. [Configuration] Feedback electrode 3 of gyro vibrating element 1
The FB signal output from is sent to the self-excited vibration circuit 6 and the phase correction circuit 8. The output signal of the self-excited vibration circuit 6 is sent to the drive electrode 2. The phase correction circuit 8 is a temperature sensitive element 8a.
And the FB signal is phase-shifted by a phase amount by which a parasitic wave (null wave) is phase-shifted due to a temperature change. The phase-shifted F
The B signal is sent to the synchronous detection circuit 9. The synchronous detection circuit 9
Is synchronously detected from the detection signals output from the sub-direction vibration detection electrodes 4 and 5 and amplified by the differential amplifier circuit 10. As a result, the phase shift between the null wave, which is the main cause of the drift, and the synchronous detection signal is corrected, and the null wave can be removed from the detection signal. The detection signal from which the null wave has been removed is sent to the smoothing amplifier circuit 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration gyroscope detection circuit, and more particularly, it aims to stabilize the performance of a vibration gyroscope by removing false signal components due to parasitic vibration from a detection signal to improve detection accuracy. A vibration gyro detection circuit.

[0002]

Vibratory gyroscopes are well known in the art.
The angular velocity is detected by detecting the sub-vibration due to the Coriolis force induced by the vibration in the main direction. The vibrating gyroscope is much cheaper than the inertial gyroscope and the optical fiber gyroscope, but the detection sensitivity changes due to the characteristic change due to the temperature possessed by the piezoelectric body, in particular, the change in the dielectric constant, the piezoelectric constant, and the elastic constant. Or a parasitic signal change occurs due to manufacturing error. Therefore, there is a problem in that the detection signal of the vibrating gyroscope causes a drift, which deteriorates the sensor function.

Conventionally, attempts have been made to solve this problem. For example, in Japanese Unexamined Patent Publication No. 3-172714, two synchronous detection circuits are provided to correct the sensitivity change due to the detection phase shift. .

[0004]

However, the above-mentioned conventional technique is effective when the detected signal to be synchronously detected is composed of only the signal component proportional to the angular velocity, but it is proportional to the angular velocity. It is not very effective in removing a parasitic wave component called a null wave included in the detected wave signal composed of only the signal component. The reason is that the null wave itself is synchronously detected and remains in the detection signal of the final output.

An object of the present invention is to eliminate the above-mentioned problems of the prior art, eliminate null waves with high accuracy even if there is a temperature change, and effectively suppress drift due to temperature or the like. To provide a circuit.

[0006]

To achieve the above object, the present invention provides an angular velocity from a vibration in a sub-direction perpendicular to the main direction, which is generated when a gyro vibrating element is vibrated in the main direction. In the vibrating gyro detection circuit for detecting, the feedback signal obtained from the gyro vibrating element is transferred by the phase shift means by a phase amount by which the parasitic wave (null wave) is phase-shifted by temperature change, and by the phase shift means. And a detection circuit that detects a detection signal generated by the vibration in the sub-direction as a detection signal.

[0007]

According to the present invention, even if the null wave is phase-shifted due to a change in the ambient temperature, the feedback signal as the detection signal always has a predetermined phase relationship with the null wave.
When the detection signal is detected by the detection circuit, the null wave is completely canceled. Therefore, the null wave can be accurately removed even if the temperature changes, and the drift due to the temperature or the like can be effectively suppressed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of a vibration gyro detection circuit according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a gyro vibrating element, and the cross-sectional shape thereof may be square, triangular, circular or the like, or a tuning fork type. The gyro vibrating element 1 is provided with a drive electrode 2, a main-direction vibration detection electrode (feedback electrode) 3, and sub-direction vibration detection electrodes 4 and 5.

The FB signal output from the feedback electrode (hereinafter abbreviated as FB electrode) 3 is input to the self-excited oscillation circuit 6 and the phase correction circuit 8 of the detection signal generation circuit 7 via a voltage follower composed of an operational amplifier. The self-excited oscillating circuit 6 amplifies and phase-shifts the FB signal and supplies it to the drive electrode 2 as a drive voltage.

In the phase correction circuit 8, as shown in FIG. 2, a temperature sensitive element 8a is used as an input side resistance. In this phase correction circuit 8, the magnitudes of the capacitors and resistors are changed to C1, C2, R1 and R as shown in the figure.
2 and the self-excited vibration frequency is f, 2πfC2 R
If 2 = 1 / 2.pi.fC1 R1 then the ratio Vo / Vi of the input signal to the output signal and the phase .theta.

[0011]

[Equation 1] In the phase correction circuit 8, the phase θ
Changes in proportion to the change rate .DELTA.R1 / R1 of the resistance R1. The FB signal whose phase is corrected by the phase correction circuit 8 is input to the synchronous detection circuit 9 through a charge amplifier including an operational amplifier. In this embodiment, the synchronous detection circuit 9 is a MOS FET.
The FB signal is input to the gate of the MOS FET.

On the other hand, the sub-direction vibration detection electrodes 4 and 5
The detection signal detected by is amplified by the differential amplifier 10, synchronously detected by the synchronous detection circuit 9, and input to the smoothing amplifier 11.

Next, regarding the operation of the main part of this embodiment,
This will be described with reference to FIGS. In these figures,
(a) shows the detected signal, (b) shows the detected signal component, and (c) shows the detected null wave component. The detected signal a is a signal input to the synchronous detection circuit 9 in FIG. 1, and the detected signal component b and the detected null wave component c are the waveforms of the output signal of the differential amplifier 10.

FIG. 3 shows the waveform of each signal when there is no temperature drift. At this time, the phase relationship between the detected signal a and the detected null wave component c is shifted by 90 ° as shown. Therefore, in the detection period, that is, in the period when the detection signal a is positive, the null wave component c to be detected is canceled by the positive and negative components,
A detection signal containing no null wave component is supplied to the smoothing amplifier 11.

Here, when temperature drift occurs in the vibrating gyroscope, as shown in FIG.
The detected null wave component c is phase-shifted by Δθ, and the phase difference from the detected signal a is not 90 °. Therefore, if the phase correction circuit 8 does not exist in the present embodiment, the synchronous detection circuit 9 performs synchronous detection with the detection signal a that is not phase corrected, so that the detected null wave component c is positive and negative as shown in the figure. That is, the null wave component is mixed in the detection signal, without being canceled by the above component.

However, in this embodiment, since the phase correction circuit 8 is provided, the detection signal a is phase-shifted by Δθ by the phase correction circuit 8 as shown in FIG. As a result, the detected null wave component c is canceled again by the positive and negative components by the synchronous detection, and the detection signal containing no null wave component is supplied to the smoothing amplifier 11.

The temperature sensitive element 8a is an element having such a characteristic that the phase correction circuit 8 shifts the phase of the detection signal a by the amount of the temperature drift of the detected null wave component c according to the environmental temperature. Of course there is.

As described above, according to this embodiment, when a temperature drift occurs in the vibrating gyroscope, the detected signal a is also phase-shifted by the same amount Δθ as the phase-shifted null wave component c of the detected wave. Since the null wave component c of the detected wave is
Disappears during synchronous detection, and a highly accurate detection signal can be obtained. In general, most of the detected wave signal is a null wave due to manufacturing error. In other words, as is clear from FIG. 3, the signal component of the detected wave signal is much smaller than the null wave component. Therefore, automatically adjusting the phase of the detection signal using the temperature sensitive element is very effective in reducing the drift. Further, when the phase correction circuit 8 corrects the signal, the amplitude also changes slightly, as is clear from the above equation. However, in the present embodiment, since it is not the detected wave but the detected signal that changes in amplitude, there is almost no adverse effect on the synchronous detection, and the null wave component is integrated and canceled by the detection, and at this time the detected wave is detected. The amplitude of the signal component is unchanged. Therefore, a highly accurate detection signal can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, 20 is a phase correction circuit, and 21
Indicates a smoothing circuit, and other symbols indicate the same as or equivalent to those in FIG.

In this embodiment, the temperature sensitive element 8a is used as the feedback resistance of the phase correction circuit 20, and the self-excited vibration circuit of the drive electrode 2 is formed by the phase correction circuit 20 and the smoothing circuit 21. Is characterized by.

The temperature sensitive element 8a of the phase correction circuit 20 changes its resistance value when the environmental temperature changes. Therefore, the phase correction circuit 20 shifts the phase of the FB signal output from the FB electrode 3 by Δθ and outputs it to the synchronous detection circuit 9.
As a result, similarly to the first embodiment, the null wave component c to be detected can be eliminated at the time of synchronous detection, and a highly accurate detection signal can be obtained. In this embodiment, since the self-excited oscillation circuit of the drive electrode 2 is formed by the phase correction circuit 20 and the smoothing circuit 21, the drive voltage applied to the drive electrode 2 slightly varies in amplitude. There is an advantage that the number of circuit elements is smaller than that of the first embodiment and the cost can be reduced.

Although the above embodiment has been described by using the piezoelectric type gyro vibrating element 1, the present invention is not limited to this, and the gyroscope driven by electrostatic force and driven by thermal stress. Of course, it can be applied to a gyroscope or a gyroscope driven by electromagnetic force.

[0023]

As is apparent from the above description, according to the inventions of claims 1 to 5, the phase shift between the null wave, which is the main cause of the drift, and the synchronous detection signal is corrected, and the corrected synchronization is corrected. Since the detected signal is detected by the detected signal, a null wave can be removed from the detected signal, and a highly accurate vibration gyro detection circuit can be provided.
Further, it is possible to effectively reduce the adverse effect due to the temperature drift, which is a problem in the vibration gyroscope.

According to the invention of claim 3, at low cost,
The vibration gyro detection circuit of the present invention can be realized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific example of the phase correction circuit of FIG.

FIG. 3 is a waveform diagram showing a waveform example of a detected signal, a detected signal component, and a null wave component when there is no drift.

FIG. 4 is a waveform diagram showing a waveform example of a detection signal and a null wave component when there is a drift and no phase correction circuit.

FIG. 5 is a waveform diagram showing a waveform example of a detection signal and a null wave component when there is a drift and a phase correction circuit.

FIG. 6 is a circuit diagram showing a configuration of a second exemplary embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gyro vibrating element, 2 ... Drive electrode, 3 ... Main direction vibration detection electrode (feedback electrode), 4, 5 ... Sub direction vibration detection electrode, 6 ... Self-excited vibration circuit, 7 ... Detection signal generation circuit,
8 ... Phase correction circuit, 9 ... Synchronous detection circuit, 10 ... Differential amplification circuit, 11 ... Smoothing amplification circuit, 20 ... Phase correction circuit, 21
... Smoothing circuit.

Claims (5)

[Claims] 1. A vibrating gyroscope detecting circuit for detecting an angular velocity from a vibration in a sub-direction perpendicular to the main direction, which is generated when the gyro vibrating element is vibrated in a main direction. The feedback signal is generated by the vibration in the sub-direction by a means for shifting the phase of the parasitic wave (null wave) by a phase shift due to a temperature change, and the feedback signal transferred by the phase shifting means as a detection signal. And a detection circuit for detecting the detection signal, wherein the residual component after detection of the null wave included in the detection signal is removed. 2. The vibration gyro detection circuit according to claim 1, wherein a feedback signal before being phase-shifted by the phase shift means is supplied to a self-excited vibration circuit, and the self-excited vibration circuit causes the gyro vibrating element to operate. A vibrating gyro detection circuit, wherein a drive signal for vibrating in a main direction is generated. 3. The vibrating gyroscope detection circuit according to claim 1, wherein a self-excited vibrating circuit is constituted by a phase shifting means for shifting the phase of the feedback signal and a smoothing circuit, and the self-excited vibrating circuit comprises the gyro vibrating element. A vibrating gyroscope detection circuit characterized in that a drive signal for vibrating in a main direction is generated. 4. The vibration gyro detection circuit according to claim 1, wherein the phase shift means uses a temperature sensitive element as an input resistance or a feedback resistance, and the phase of the detection signal is changed according to an environmental temperature. And a vibration gyroscope detecting circuit for shifting the phase of the null wave by the temperature drift amount. 5. The vibration gyro detection circuit according to claim 1, wherein the gyro vibration element is a piezoelectric drive type, an electrostatic force drive type,
A vibration gyro detection circuit, which is one of a thermal stress drive type and an electromagnetic force drive type.