JP2001188011A - Vibrating gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibrating gyro outputting an angular velocity detecting signal that Coriolis force is peak-held and a voltage is amplified to be digitized. SOLUTION: A level of a reference signal that an L signal from a vibrator 1 and R signal are added in an adder circuit 2, is set constantly in an AGC circuit 4 and a phase of the signal is adjusted in a phase-shift circuit 5, and then the vibrator 1 is excited. The reference signal is formed to a rectangular wave in a rectangular wave forming circuit 6, and a timing signal for a sample- hold is provided a V-T conversion circuit 8 through a microprocessor 7. A differential amplification circuit 3 sample-holds a sum of differential component of the L and R signals and Coriolis force in a sample-hold circuit 81, integrates it in an integration circuit 82, compares it with a fixed level in a comparator 83, and provides a digital signal with a duty factor corresponding to Coriolis force to the microprocessor 7 as the angular velocity detecting signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating gyroscope, and more particularly, to a vibrating gyroscope for detecting an angular velocity from an output of a bimorph vibrator used for a camera shake correction or a navigation system.

[0002]

2. Description of the Related Art FIG. 12 is an external perspective view showing an example of a bimorph vibrator used in a vibrating gyroscope. In FIG. 12, the bimorph vibrator 1 is configured such that two piezoelectric elements are attached with the polarization directions being opposite to each other, so that the cross-section becomes rectangular. When the vibrator 1 is driven to vibrate in a vertical vibration mode in a direction perpendicular to the surface (X-axis direction) and rotated at an angular velocity (Ω) in a longitudinal direction (Z-axis direction), the driving direction is changed by Coriolis force. Vibration occurs in a transverse vibration mode synchronized with a vertical direction (Y-axis direction).

Since the amplitude of the lateral vibration is proportional to the angular velocity, the value of the angular velocity is detected by using this. Vibrator 1
Although not shown, left and right electrodes are provided on one main surface, and full-surface electrodes are provided on the other main surface.
The (left) signal and the R (right) signal are output. In such a vibrator 1, it is necessary to individually adjust balance, null voltage (also referred to as offset voltage and neutral point voltage), and sensitivity.

FIG. 13 is a block diagram of an angular velocity detecting circuit for obtaining the output of the vibrator 1 shown in FIG. FIG.
, The difference between the two outputs of the vibrator 1 is
1, the amplitude waveform is detected by the synchronous detection circuit 22 and smoothed by the smoothing circuit 23 to become a DC voltage.
DC amplification is performed by the C amplifier 24. This signal contains a null voltage. When the signal is amplified by the DC amplifier 24,
Since the null voltage is also amplified, the DC component is cut by, for example, a DC cut circuit 25 constituted by a filter, and the remaining low-frequency AC signal corresponding to the change in the angular velocity is further amplified by the amplifier circuit 26 to be converted into an analog signal. Is output as Here, the analog signal is converted into a digital signal by the A / D converter 27, and is supplied to the microprocessor 28 as an angular velocity detection signal to control the vibration of the camera and perform control for navigation.

[0005]

In the angular velocity detection circuit shown in FIG. 13, an L component and an R component signals are output from the vibrator 1 and a differential signal is output by the differential amplifier circuit 21. , The null voltage should be 0 V, but if the left and right balance is shifted, the voltage of the shifted component is output as the null voltage. If the gain of the DC amplifier 24 is increased to amplify the signal component, the DC voltage is saturated by the included null voltage, so that the absolute upper limit of the amplification degree of the DC amplifier is determined.

In order to cut a DC component by the DC cut circuit 25, for example, if a high-pass filter that allows only a signal of 0.1 Hz or more to pass is constructed, a large-capacity capacitor of 20 .mu.F and a 1 M.OMEGA. A high-pass filter with a combination of resistors is required, and the device becomes large.

Further, in the circuit shown in FIG. 13, the output of the differential amplifier circuit 21 is output with the left and right signal components shifted in phase, and the output is output with the left and right signal components shifted in amplitude. There is. Since the left and right signal components are sin waves, if the amplitude is shifted, only the amplitude of the differential output needs to be changed. However, if the left and right signal components are out of phase, the phase is shifted with respect to the reference signal. There is also a problem that the output signal is output.

As another conventional example, Japanese Patent Publication No. Hei 6-13970
Japanese Patent Application Laid-Open No. H11-163873 discloses that a drive signal is supplied to a detection side surface of a vibrator so that a phase difference angle formed by a vector of an output voltage based on an angular velocity when the vibrator rotates and a vector of a null voltage when the vibrator is stationary is 90 degrees. It describes that an angular velocity is detected from a phase difference between a composite vector of the null voltage and a null voltage.

However, in this example, although the amplitude of the oscillator output has a linearity, the relationship between the phase difference and the sensitivity is not basically linear, and the nonlinearity fluctuates under the influence of the null phase. There is a disadvantage that it is easy. Therefore, it is desirable to digitize the amplitude value of the Coriolis force.

Japanese Patent Application Laid-Open No. Sho 62-150 discloses such an example.
Japanese Patent Publication No. 116 describes that sampling and holding are performed at a time when an angular velocity signal due to driving of oscillation becomes maximum and minimum.

Japanese Patent Application Laid-Open No. Hei 7-260493 describes that a difference between passing currents of a piezoelectric element is detected, and sample-hold is performed at a timing when the detected displacement speed of the vibrator becomes zero. However, it does not describe how to digitally process the sampled and held signal.

SUMMARY OF THE INVENTION It is, therefore, a main object of the present invention to provide an angular velocity detecting circuit in a vibrating gyroscope which samples and holds and amplifies and digitizes a Coriolis force irrespective of the position of the Coriolis force phase.

It is another object of the present invention to provide an angular velocity detecting circuit in a vibrating gyroscope capable of detecting and correcting a null voltage.

[0014]

The invention according to claim 1 is
A vibrating gyroscope that excites a vibrator in the X-axis direction and detects vibration due to Coriolis force generated in the Y-axis direction when the vibrator is rotated around the Z-axis. Driving means for generating a reference signal based on the signal and exciting the vibrator; signal extracting means for extracting a differential signal including a Coriolis force based on the first and second signals output from the vibrator; Timing signal generating means for generating a timing signal for sampling and holding the Coriolis force based on a reference signal output from the driving means,
Voltage-time axis conversion means for sampling and holding the extracted differential signal based on the timing signal, expanding a minute voltage change of the differential signal on the time axis, and outputting the signal as an angular velocity detection signal . Although the sampling point is preferably near the peak value in terms of efficiency, it goes without saying that the sampling point is established without being specified at any phase.

In the invention according to claim 2, the vibrator according to claim 1 has a small difference between amplitude and phase, and
And first and second electrodes for outputting the first and second signals and a full-surface electrode, and the driving means adds the first and second signals and outputs the sum as a reference signal; And level adjusting means for adjusting the phase of the reference signal output from the level control means and outputting the adjusted reference signal to the entire surface electrode.

According to a third aspect of the present invention, the voltage-time axis converting means according to the first or second aspect includes a sample-and-hold means for sampling and holding a differential signal including a Coriolis force based on a timing signal; Integrating means for integrating the output signal, and comparing means for comparing the integrated signal at a predetermined level, expanding the signal on a time axis, and outputting the result.

According to a fourth aspect of the present invention, the voltage-time axis conversion means of the first or second aspect samples a differential signal including a Coriolis force based on a timing signal, and linearly reduces a peak value by a droop characteristic. And a comparing means for comparing a linearly decreasing signal at a predetermined level and expanding and outputting the time axis.

According to the fifth aspect of the present invention, there is provided a means for generating a timing signal for causing a sampling point by the sample and hold means to be different from a specific phase of Coriolis force and another phase at another wavelength, and a sample and hold means by the sample and hold means. The values are compared to infer a null differential voltage, and a predetermined level of the comparing means is controlled based on the inferred null differential voltage.

According to a sixth aspect of the present invention, the timing signal generating means of any one of the first to fifth aspects detects the leading edge and the trailing edge of the reference signal and counts the clock signal. To output a timing signal.

[0020]

FIG. 1 is a block diagram of a vibrating gyroscope according to an embodiment of the present invention. In FIG. 1, a vibrator 1 is provided with a left electrode 1L, a right electrode 1R, and a full-surface electrode 1C, and the left electrode 1L and the right electrode 1R have resistors R1 and R1, respectively.
2, a voltage + V is applied. + V is usually a middle positive potential or a reference potential. Left electrode 1L, right electrode 1R
The L signal, which is the first signal, and the R signal, which is the second signal, are output including Coriolis forces, respectively, and output from an adder circuit 2 as an adder, and a differential amplifier circuit 3 as a signal extractor. Given to. The addition circuit 2 adds the L signal and the R signal and outputs an L + R signal. Thus, the addition circuit 2
By adding the L signal and the R signal, the Coriolis force is eliminated and a stable feedback signal is obtained.

The above-mentioned feedback signal is supplied as a reference signal to an AGC circuit 4 as a level control means, and becomes a drive voltage having a constant level, and this drive voltage is passed through a phase shift circuit 5 as a phase adjustment means. To the entire surface electrode 1C. The phase shift circuit 5 adjusts the phase of the output of the adder circuit 2, and adjusts the phase difference between the output of the adder circuit 2 and the drive voltage applied to the entire surface electrode 1C to oscillate stably at a desired frequency. In this embodiment, the phase difference is almost zero. The vibrator 1, the adding circuit 2, the AGC circuit 4, and the phase shift circuit 5 constitute an oscillation circuit. Also, the addition circuit 2
The AGC circuit 4 and the phase shift circuit 5 constitute driving means for exciting the vibrator 1.

The reference signal output from the adding circuit 2 is supplied to a rectangular wave forming circuit 6 composed of, for example, a comparator, and a rectangular wave is formed and supplied to the microprocessor 7 as a timing extraction signal. Note that the driving voltage of the output of the phase shift circuit 5 may be supplied to the rectangular wave forming circuit 6 as a reference signal, as shown by the dotted line in FIG.

The microprocessor 7 discriminates the leading edge and the trailing edge of the timing extraction signal, counts the time from the leading edge to the trailing edge of the timing extraction signal using a reference pulse, and identifies the frequency based on the count value. . Therefore, the microprocessor 7 can easily determine the relationship between the frequency and the phase of the reference signal output from the adder circuit 2. Further, the microprocessor 7 outputs a timing signal for sampling and holding to the VT conversion circuit 8 which is a voltage-time axis conversion means based on the timing extraction signal. That is, the timing signal generating means is constituted by the rectangular wave forming circuit 6 and the microprocessor 7.

The differential amplifying circuit 3 to which the L signal and the R signal output from the vibrator 1 are given outputs the differential signal as the output to the VT conversion circuit 8. VT conversion circuit 8
Is for diffusing a minute voltage change ΔE into a large time region ΔT. This is because the output of the differential amplifier circuit 3 has a low level and needs to be amplified. In the conventional DC amplifier circuit, as described in the conventional example, the output is saturated by the null voltage, so that the upper limit of the amplification factor is determined. It solves the problem of having been lost.

On the other hand, in the embodiment of the present invention,
The output voltage of the differential amplifier circuit 3 having a small level is spread over a region ΔT of a large time, which is compared with a predetermined level by a comparator to output a digital signal. Therefore, V-
The T conversion circuit 8 includes a sample and hold circuit 81 as a sample and hold means, an integration circuit as an integration means,
A comparator 83 as comparison means is provided.
The sample hold circuit 81 samples and holds the output of the differential amplifier circuit 3 based on the timing signal from the microprocessor 7 and supplies the output to the integration circuit 82. The integration circuit 82 integrates the sampled and held signal and outputs the signal to the comparator 83. The comparator 83 compares the integrated output with a predetermined level and outputs a digital signal having a duty ratio according to Coriolis to the microprocessor 7.

FIGS. 2 and 3 are waveform diagrams of each part of the angular velocity detecting circuit shown in FIG. Next, a signal output from the vibrator 1 will be described with reference to FIG. Vibrator 1
The L signal (a) and the R signal (b) output from are slightly different in amplitude and phase. Taking the difference between the L signal (a) and the R signal (b) results in LR (c), and taking the sum as L + R (d).

In LR (c), the larger the phase shift between the L signal and the R signal, the more the zero cross point moves. This LR signal is also called a null differential voltage. LR
Coriolis force is superimposed on the signal and output, and differential +
Output as Coriolis. The Coriolis force has a property that it cannot be separated from the differential voltage even if it is desired. The reason is that the Coriolis force is not output as an actual signal as shown in FIG. In the following description, it is assumed that the LR signal means differential + Coriolis force. Coriolis force (e) is L + R
(D), the Coriolis force becomes maximum and minimum near the maximum and minimum points of L + R. When the vibrator 1 is rotated left and right, the amplitude of the Coriolis force (e) changes, and the phases of the L signal (a) and the R signal (b) change with respect to L + R (d).

As described above, the L signal (a) and the R signal (b) output from the left electrode 1L and the right electrode 1R of the vibrator 1 shown in FIG. 2 are added by the adding circuit 2, and shown in FIG. The L + R signal (d) is supplied to the AGC circuit 4 as a reference signal, and the level is made constant. Further, after the phase of the reference signal is adjusted by the phase shift circuit 5, the reference signal is applied to the entire surface electrode 1C of the vibrator 1 so that the oscillation circuit keeps oscillating. The L + R signal output from the adding circuit 2 is formed into a rectangular wave by the rectangular wave forming circuit 6 and supplied to the microprocessor 7 as a timing extraction signal.

Here, as shown in FIG. 2, the Coriolis force (e) becomes maximum and minimum near the maximum and minimum points of the L + R signal (d) as the reference signal. This phase depends on the phase of the oscillation circuit and the phase shift due to the detection resistor. The reference signal can be arbitrarily adjusted by the phase shift circuit 5. Note that the L signal (a) and the R signal (b) shown in FIG. 2 may be used independently as long as the reference signal has a stable phase and frequency. However, since a Coriolis force is superimposed on the L signal and the R signal, a square wave is not preferable because a phase shift from the differential occurs or the duty fluctuates.

On the other hand, the differential amplifier circuit 3 outputs an LR signal representing the difference between the L signal and the R signal. The LR signal is applied to the VT conversion circuit 8 and sampled and held by the sample and hold circuit 81. Here, the microprocessor 7
As shown in FIG. 2F, the leading edge and the trailing edge of the reference signal formed in the rectangular wave are detected as shown in FIG. The count value of one cycle of the reference signal is calculated by the reference clock signal as shown or a clock signal similar thereto.
FIG. 2H shows the timing at which a timing signal for sampling and holding is output at a timing of, for example, 1/4 of the reference signal.

FIG. 3A shows a reference signal, and FIG.
Indicates a sample-hold timing signal, and the sample-hold circuit 81 outputs L based on the timing signal.
The -R signal is sampled and held as shown in FIG. It is most efficient to sample and hold at the peak point of the Coriolis force most preferably. However, it is not always necessary to sample and hold at the peak point, and sample and hold may be performed near the peak point. The sample-hold voltage depends on the angular velocity and is integrated by the integration circuit 82, and the signal waveform linearly slopes down to the right with time as shown in FIG. , L-R based on the next timing signal
The signal is sampled and held again.

The integrated signal output from the integrating circuit 82 is applied to a comparator 83, which compares the integrated signal with a predetermined level.
The digital signal is converted into a digital signal having a duty ratio corresponding to the Coriolis force shown in (e), and is output to the microprocessor 7 as an angular velocity detection signal. Microprocessor 7
Calculates the angular velocity by counting this digital signal with a reference clock.

The VT conversion circuit 8, as shown in FIG.
If the time constant is increased and the hold time is lengthened by reducing the leak current of the integrating circuit 83, the time domain ΔT1 becomes larger as ΔT2 for the same change ΔE of the angular velocity voltage, and the resolution or sensitivity increases. I do. Therefore, the time domain can be arbitrarily expanded by arbitrarily setting the time from one sample-hold timing to the next sample-hold timing.

In this case, the hold time may exceed one cycle of the reference signal. This means that the conventional synchronous detection-integration-DC amplification is amplification at the voltage level, whereas in this embodiment, it is at the time axis level. In the conventional example, the DC amplifier has an absolute upper limit of the amplification degree due to the power supply voltage, whereas the present invention basically means that an infinite amplification degree can be obtained.

By expanding the time domain in this way, the LR signal during that time can be discarded. The driving frequency of the bimorph vibrator is several kHz to 100 kHz.
In camera shake correction and car navigation systems, the upper limit of the angular velocity signal is at most 50H.
Since the LR signal may be partially discarded because there is only a signal equal to or less than z, in this embodiment, 1000 is used.
This means that it can be expanded more than twice.

FIG. 5 is a block diagram of another embodiment of the present invention. In the example shown in FIG. 1 described above, the reference signal is converted into a rectangular wave, and the sample and hold timing signal is generated by the software processing of the microprocessor 7.
In the example shown in FIG. 5, a reference signal output from the adder circuit 2 is supplied to a timing signal generation circuit 9, and a timing signal for sample and hold is generated by a hardware configuration and supplied to a sample and hold circuit 81. It is.
That is, the timing signal generation circuit 9 realizes the software processing of the microprocessor 7 shown in FIG. 1 with a hardware configuration, and includes a detection circuit for detecting a leading edge and a trailing edge of a reference signal, and a leading edge to a trailing edge. And a logic circuit that outputs a timing signal based on the count value of the counter. As a result, the timing signal generating circuit 9 alone constitutes a timing signal generating means.

The digital output output from the comparator 83 may be input to a microprocessor 7 similar to that shown in FIG. 1 and subjected to software processing, or the digital signal may be counted by a hardware circuit using a reference clock, and the angular velocity signal may be calculated. You may make it output.

FIG. 6 is a circuit diagram showing a sample and hold circuit used in still another embodiment of the present invention. In the embodiment shown in FIGS. 1 and 5, the VT conversion circuit 8
Is sampled and held by the sample and hold circuit 81, and the sampled voltage is integrated by the integration circuit 82. In this embodiment, the integration circuit is not required by using the droop characteristic of the sample and hold circuit.

For this reason, the sample and hold circuit 81 shown in FIG. 6 is conventionally known, and includes an input buffer BA1, an output buffer BA2, and a transistor TR.
1, TR2, an FET, a resistor R1, and a capacitor C. When a timing signal is given from the microprocessor 7 to the emitter of the transistor TR1, the transistors TR1, TR2 and the FET are sequentially turned on, and the input buffer BA1 is turned on. Is stored in the capacitor C. When the FET is cut off, the charged voltage of the capacitor C leaks via the resistor R1 connected between the source and the gate of the FET.

FIGS. 7 and 8 are diagrams showing the sample-hold signal and the droop characteristic by the sample-hold circuit shown in FIG. If the resistor R1 shown in FIG. 6 is not provided, this is a very general sample-and-hold circuit, and converts the level of a signal with a slope determined by the leak current i in the following equation.

ΔV / ΔT = i (leak) / C However, if the sensitivity amplification is adjusted by providing the resistor R1 shown in FIG. 6, the droop characteristic shown in FIG.
A linear slope characteristic similar to that obtained by integration by the integration circuit can be provided. The slope of the slope becomes gentler as the resistance R1 increases. In that case, it is necessary to widen the interval between the timing pulses of the sample hold.

By comparing the sample hold output shown in FIG. 7C with a predetermined level by the comparator 83 shown in FIG. 1, the comparator 8 shown in FIG.
3 can be output.

FIG. 8 is a waveform diagram when the vibrator 1 is shaken and the Coriolis force is moving. When the peak of the Coriolis force moves, the sample-and-hold output also changes as shown in FIG. Following the movement, the duty ratio of the digital output of the comparator 83 shown in FIG. 8D changes. This duty ratio becomes the angular velocity signal.

FIGS. 9 and 10 are block diagrams showing a vibrating gyroscope according to still another embodiment of the present invention. The embodiment shown in FIGS. 9 and 10 has a Coriolis force of one.
The sample and hold points of the second wavelength and the second wavelength are made different from each other, the respective sample and hold values are compared, a null differential voltage is inferred, and the magnitude of the null differential voltage inferred in the microprocessor 7 is calculated. D / A conversion is performed, and a null voltage is removed by an offset adjusting circuit 10 as shown in FIG.
The third level is controlled.

FIG. 11 is a waveform diagram showing sample hold points. As shown in FIG. 11, after the rising position of the sample-and-hold signal is shifted from the same 90-degree phase (F1 ') after the 90-degree phase (F1) of the reference signal, the rising position is further increased by 90.
Detection is performed at a point (F2) shifted by degrees. Although it is conceivable that the form of the differential changes depending on the temperature or the like, if the value is obtained, the control can be performed by constantly monitoring the null voltage from the following equation.

F1 and F2 in FIG. 11 can be expressed by the following equations. F1 = A {(sin ωt + α) + (Bsin ωt)} F2 = A (cos ωt + α) A is the amplitude of the LR signal, and when the Coriolis force B is 0, it is expressed by the following equation.

F1 ² + F2 ² = A ² By calculating the above equation, the magnitude of the differential amplitude can be known, and the null voltage can be known from the value of A.

The operation of FIG. 10 will be described below with reference to FIG. In FIG. 11, the point F1 is the maximum point of the Coriolis force, and the point F2 is the zero point of the Coriolis force. T2, which is the comparator output time corresponding to sampling at point F2, is constant regardless of the presence of Coriolis force.

First, since the Coriolis force is zero immediately after the start of the vibrating gyro, T1 and T2 immediately after the start, ie, T1
From (0) and T2 (0), A (0) and α (0) which are the initial values of A and α of the differential input are calculated (step 1).

Next, based on the size of T2 (0), the microprocessor 7 sets the duty ratio of T2 (0) to 1: 1 via a D / A converter (included in the microprocessor 7). The level of the comparator 83 is adjusted so that T2 (t1) is measured again (step 2).

In this state, T1 (t2) is measured. T1
(T2) varies with the Coriolis force. The D / A converter is again operated by the comparator 8 so that this fluctuation is eliminated.
Adjust level 3. That is, the Coriolis force is adjusted to zero. Then, T2 (t3) fluctuates around the duty ratio of 1: 1 according to the level fluctuation of the comparator 83, the null voltage is canceled, and an output reflecting only the Coriolis force is obtained. A (t2) and α (t2) are calculated again from T1 (t2) and T2 (t1) at this time (step 3).

The above (Step 2) and (Step 3) are performed intermittently, and the value of T2 is monitored at certain intervals. When the null voltage fluctuates due to a temperature change or the like, the comparator offset level is adjusted by the action (step 2) each time. At this time, it is not always necessary to obtain A and α. However, when T2 greatly fluctuates due to an abnormal input such as an external impact, and A and α take unique values, the past A and α By judging the magnitude of the deviation from the value, the offset level adjustment can be skipped.

9 also differs from FIG. 10 only in that the D / A converter controls the offset adjustment circuit 10 instead of the comparator 83, and functions almost in the same manner as in the case of controlling the comparator 83. I do.

In the conventional example, since the null voltage is output as an integrated signal of synchronous detection, there is no means for correcting the null voltage. For this reason, with rotation at a constant angular velocity, it may happen that the angular velocity output and the null voltage cannot be distinguished.

On the other hand, in this embodiment, the condition is that the difference between the Coriolis forces of two signals to be detected successively is small, but the null voltage is always zero due to the midpoint potential of these signals. Control can be performed as described above, and the influence of the temperature change of the null voltage can be canceled.

The embodiments shown in FIGS. 9 and 10 may be applied to the embodiment shown in FIG.

In the above-described embodiment, the case where the present invention is applied to a bimorph vibrator is described. However, the present invention is not limited to this. For example, a vibrator in which a piezoelectric element is attached to a square or triangular prism made of metal, The present invention is applied to a piezoelectric vibrating gyroscope that outputs an L / R signal, such as a vibrator of a tuning piece type or a vibrator of a tuning fork structure using a columnar piezoelectric element, and can obtain an excitation voltage or a sum voltage with a reference signal. Applicable.

The embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0059]

As described above, according to the present invention, the reference signal is generated based on the first and second signals output from the oscillator to excite the oscillator, and the Coriolis extracted from the oscillator is generated. A differential signal including force is sampled and held by a timing signal, a minute voltage change of the sample and hold value is expanded on a time axis, and the output is compared with a predetermined level to output an angular velocity detection signal. Therefore,
As in the related art, it is possible to eliminate the need for an overlapping circuit for digitizing synchronous detection or the like, thereby reducing costs.

More preferably, the circuit configuration of the VT conversion means can be simplified by changing the slew rate of the sample and hold means as the VT conversion means to have an amplifying function.

More preferably, one of the Coriolis forces is used.
The sample and hold values are compared at a specific phase point of the wavelength and a phase point different therefrom to infer a null differential voltage, and an offset is applied to the differential signal based on the inferred null differential voltage. Can be controlled so that the null potential is always 0, and the influence of the temperature change of the null voltage can be canceled.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an angle detection circuit according to an embodiment of the present invention.

FIG. 2 is a waveform chart of each part of the angular velocity detection circuit shown in FIG.

FIG. 3 is a waveform diagram of each part of the angular velocity detection circuit shown in FIG.

FIG. 4 is a diagram showing a relationship between a time constant of an integrating circuit of the VT conversion circuit shown in FIG. 1 and resolution or sensitivity.

FIG. 5 is a block diagram showing an angular velocity detection circuit according to another embodiment of the present invention.

FIG. 6 is a circuit diagram of a sample and hold circuit used in still another embodiment of the present invention.

FIG. 7 is a waveform chart for explaining the operation of the sample and hold circuit shown in FIG. 6;

FIG. 8 is a waveform chart for explaining the operation of the sample and hold circuit shown in FIG. 6;

FIG. 9 is a block diagram showing an angular velocity detection circuit according to still another embodiment of the present invention, showing an example of removing a null voltage.

FIG. 10 is a block diagram showing an angular velocity detection circuit according to still another embodiment of the present invention, showing an example of controlling a level of a comparator.

FIG. 11 is a waveform chart for explaining the operation of the embodiment shown in FIGS. 9 and 10;

FIG. 12 is an external perspective view of a bimorph vibrator which is a background of the present invention and to which the present invention is applied.

FIG. 13 is a block diagram of a conventional angular velocity detection circuit.

[Explanation of symbols]

1 oscillator, 2 adder circuit, 3 differential amplifier circuit, 4 A
GC circuit, 5 phase shift circuit, 6 rectangular wave formation circuit, 7 microprocessor, 8 VT conversion circuit, 9 timing signal generation circuit, 10 null voltage adjustment circuit, 81 sample hold circuit, 82 integration circuit, 83 comparator.

Claims (6)

[Claims] 1. A vibrating gyroscope for exciting a vibrator in an X-axis direction and detecting vibration due to Coriolis force generated in a Y-axis direction when the vibrator is rotated around a Z-axis, wherein the vibrator is output from the vibrator. Driving means for generating a reference signal based on the first and second signals and exciting the vibrator; differential including Coriolis force based on the first and second signals output from the vibrator A signal extracting unit for extracting a signal, a timing signal generating unit for generating a timing signal for sampling and holding the Coriolis force based on a reference signal output from the driving unit, and the signal extracted by the signal extracting unit. The differential signal is sampled and held based on the timing signal generated from the timing signal generating means, and a minute voltage change of the differential signal is expanded on a time axis. A vibratory gyroscope having a voltage-time axis converting means for outputting as an angular velocity detection signal. 2. The vibrator has first and second electrodes for outputting the first and second signals, each having a slight difference in amplitude and phase, and a full-surface electrode, An adder that adds the first and second signals and outputs the same as the reference signal; a level controller that makes a level of the reference signal output from the adder constant; 2. The vibrating gyroscope according to claim 1, further comprising: a phase adjusting unit configured to adjust a phase of the reference signal output from the control unit and output the adjusted reference signal to the entire surface electrode. 3. 3. The voltage-time axis conversion means includes: a sample and hold means for sampling and holding the differential signal including a Coriolis force based on the timing signal; and an integration means for integrating an output signal of the sample and hold means. And comparing means for comparing the signal integrated by the integrating means at a predetermined level, expanding the signal on a time axis, and outputting the result.
The vibrating gyroscope according to claim 1. 4. The voltage-time axis conversion means samples the differential signal including the Coriolis force based on the timing signal, and linearly reduces a peak value by a droop characteristic. 3. The vibrating gyroscope according to claim 1, further comprising: comparing means for comparing a signal linearly reduced by the means at a predetermined level and expanding and outputting the signal on a time axis. 5. A means for generating a timing signal for causing a sampling point by said sample and hold means to be different between a specific phase of Coriolis force and another phase at another wavelength, and comparing a sample and hold value by said sample and hold means. 5. The vibrating gyroscope according to claim 3, further comprising: means for inferring a null differential voltage, and controlling a predetermined level of the comparing means based on the inferred null differential voltage. 6. The timing signal generating means detects a leading edge and a trailing edge of the reference signal and counts a clock signal.
6. The vibrating gyroscope according to claim 1, wherein the timing signal is output at a predetermined count value.