JPH05240649A - Vibration type angular velocity detector - Google Patents

Abstract

PURPOSE:To eliminate fluctuation in sensitivity and the amount of offset of each piezoelectric element without adopting any additional circuit in a vibration type angular velocity detector. CONSTITUTION:When a vehicle is producing an angular velocity, both piezoelectric elements 30a and 30b for detection generate an angular velocity vibration voltage accompanied by vibration of both vibration pieces 20a and 20b. Ant amplifier 51 amplifies the angular velocity vibration voltage to an amplification vibration voltage. Only when the amplification vibration voltage is higher than a ground level, a comparator 52 generates a comparison voltage at a high level. Only when a phase-shift control voltage of a phase-shifting circuit 42 is higher than the ground level, a comparator 53 generates a comparison voltage at a high level. An exclusive OR circuit 54 calculates an exclusive OR of both comparison voltages and then generates a gate voltage. An LPF 60 generates low-frequency components of gate voltage from the exclusive OR circuit 54 as low-frequency components. An amplifier 70 amplifies a filter voltage of the LPF 60 to an angular velocity voltage and then outputs it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detecting device, and more particularly to a vibration type angular velocity detecting device suitable for detecting the angular velocity of a vehicle or other moving body by utilizing the Coriolis force acting on a vibrator. Regarding

[0002]

2. Description of the Related Art Conventionally, in a vibration type angular velocity detecting device of this type, a driving vibrating piece is moved so as to vibrate in the vibration direction of a moving body, as disclosed in JP-A-62-52410. The vibrating piece for detection is extended from the vibrating piece for detection so that it vibrates in a direction perpendicular to the vibrating piece for driving when an angular velocity is generated in the moving body. The driving piezoelectric element is fixed to the driving vibrating piece so as to vibrate by the piezoelectric action, and the detecting piezoelectric element is fixed to the detecting vibrating piece so as to detect the angular velocity of the moving body by the piezoelectric conversion action. The device main body is configured by fixing the vibration reference piezoelectric element to the drive vibrating piece so as to piezoelectrically convert the vibration of the drive vibrating piece and has the same characteristics as the detection piezoelectric element, and refers to the phase shift circuit. Phase of the piezoelectric conversion output of the piezoelectric element for The rectifier circuit rectifies the piezoelectric conversion output of the vibration reference piezoelectric element using the rectification circuit, and the difference between the reference value and the rectification output of the rectification circuit, which has a fixed relationship with the detection output of the detection piezoelectric element, is calculated. The differential amplification is performed by the dynamic amplification circuit, and the phase control output of the phase shift circuit and the differential amplification output of the differential amplification circuit are combined and driven so that the piezoelectric conversion output of the vibration reference vibrating piece becomes constant. There is a piezoelectric element for use in the application, and the detection output of the detection piezoelectric element is synchronously detected by the synchronous detection circuit based on the phase control output of the phase circuit to generate an angular velocity output signal.

[0003]

By the way, in such a structure, the detection output of the detection piezoelectric element is made to be the phase of the phase shift circuit by making the vibration amplitude of the vibration reference piezoelectric element constant as described above. Synchronous detection is performed by the synchronous detection circuit based on the control output, and it is possible to prevent variation in the sensitivity of each piezoelectric conversion element and variation in the offset amount in the detection output of the detection piezoelectric element due to ambient temperature. However, as described above, since it is necessary to control the vibration amplitude of the vibration reference piezoelectric element to be constant, extra circuits such as a rectifier circuit, a differential amplifier circuit, and a combination circuit must be adopted, and the angular velocity detection There is a problem that the circuit configuration of the device becomes complicated. Further, since there is a certain limit in improving the accuracy of amplitude control, it is extremely difficult to make the fluctuation of the vibration amplitude substantially zero with respect to the temperature fluctuation. As a result, it has been difficult to substantially eliminate the temperature variation of the sensitivity of each piezoelectric element and the variation of the offset amount during the detection output of the detection piezoelectric element.

Therefore, in order to cope with such a situation, the present invention does not employ various extra circuits for making the vibration amplitude constant, as described above, in the vibration type angular velocity detecting device. It is intended to eliminate fluctuations in the sensitivity and offset amount of the piezoelectric element.

[0005]

In solving the above problems, a structural feature of the present invention is that a vibrating member provided vibratably in a part of a moving body and the vibrating member fixed to the vibrating member. And a driving piezoelectric element for driving so as to vibrate in one direction, and an angular velocity vibration detection signal for detecting a vibration that is fixed to the vibrating member and that occurs in the vibrating member in a direction intersecting with the one direction according to the angular velocity of the moving body. A piezoelectric element for detecting, a vibration reference piezoelectric element fixed to the vibrating member and having the same characteristics as the piezoelectric element for detection to detect the vibration of the vibrating member and generate a vibration reference signal, Phase control means for controlling the phase of the vibration reference signal to be shifted by approximately 90 degrees and providing it as a phase control output to the driving piezoelectric element to drive it, and the angular velocity vibration detection based on the phase shift control output. Signal In a vibration type angular velocity detection device comprising a synchronous detection means for carrying out a period detection and generating as an output signal representing the angular velocity, a first digitizing processing means for digitizing the phase shift control output and the angular velocity vibration detection signal are provided. Second digitizing processing means for digitizing, and exclusive OR processing means for performing exclusive OR processing of both digitized processing outputs from the first and second digitizing processing means and generating as the output signal. By the above, the synchronous detection means is configured.

[0006]

According to the present invention, the driving piezoelectric element is moved in one direction by the driving piezoelectric element in cooperation with the phase control means. When an angular velocity occurs, the detection piezoelectric element detects a vibration generated in the vibrating member in a direction intersecting the one direction according to the angular velocity, and the vibration reference piezoelectric element is the same as the detection piezoelectric element. Based on the characteristic of 1., a vibration reference signal is generated by detecting vibration in one direction of the vibrating member, and the phase shift control means shifts the phase of the vibration reference signal by about 90 degrees. It is controlled and applied as a phase control output to the driving piezoelectric element. In such a state, the first digitization processing means of the synchronous detection means digitizes the phase shift control output, and the second digitization processing means
Digitization processing means digitizes the angular velocity vibration detection signal, and the exclusive OR processing means performs exclusive OR processing of both digitized processing outputs from the first and second digitization processing means. And outputs as a synchronous detection output indicating the angular velocity. Therefore, the synchronous detection means is composed of both the digitization processing means and the exclusive OR processing means, and the angular velocity vibration detection signal is synchronously detected in relation to the phase regardless of the amplitude. Since the angular velocity output can be obtained, it is possible to remarkably simplify the circuit configuration of the vibration type angular velocity detecting device of this type, and surely eliminate the fluctuations in the sensitivity and the offset amount of each piezoelectric element.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a vibration type angular velocity detecting device according to the present invention applied to detection of angular velocity of a rotation angle of a vehicle. The angular velocity detecting device is composed of a detecting device main body S and a signal processing circuit E connected to the detecting device main body S. The detection device main body S has a drive element 10 formed of a metal material in a tuning fork shape.
At the base portion 11, it is vertically provided on a part of the vehicle body of the vehicle. Further, the drive element 10 has a pair of drive plate-shaped vibrating pieces 12 and 13 that extend from the base portion 11 of the drive element 10 in parallel with each other and extend upward in the longitudinal direction.

The driving element 10 is a pair of driving piezoelectric elements 1
4a, 14b and a pair of vibration reference piezoelectric elements 15a, 1
The driving piezoelectric element 14a is fixed to the left surface of the vibrating reed 12 with one electrode thereof, and vibrates the vibrating reed 12 in the left-right direction by its piezoelectric conversion action. On the other hand, the driving piezoelectric element 14b is fixed to the right surface of the vibrating piece 13 by one of the electrodes, and vibrates the vibrating piece 13 in the left-right direction by its piezoelectric conversion action. However,
The characteristics of both piezoelectric elements 14a and 14b are substantially the same including the temperature characteristics.

Further, the vibration reference piezoelectric element 15a is fixed to the right side surface of the vibrating piece 12 by one electrode thereof,
Due to the piezoelectric conversion action, the vibration of the vibrating piece 12 is detected as a vibration reference voltage. On the other hand, the vibration reference piezoelectric element 15b
Is fixed to the left side surface of the vibrating piece 13 with one electrode thereof, and detects the vibration of the vibrating piece 13 as a vibration reference voltage by its piezoelectric conversion action. Both of these piezoelectric elements 15a,
The electrodes 15b are connected to each other at their respective other electrodes to form a common terminal, and the vibration reference voltage is output from this common terminal.

Further, the detecting device main body S has a pair of detecting plate-like vibrating pieces 20a and 20b formed of a metal material, and the vibrating piece 20a has its plate thickness direction in the plate thickness direction of the vibrating plate 12. And extends coaxially from the vibrating reed 12 upward in the longitudinal direction. On the other hand, the vibrating piece 20b has its plate thickness direction orthogonal to the plate thickness direction of the vibrating piece 13 and extends coaxially upward from the vibrating piece 13 in a longitudinal shape. However,
When each of the vibrating pieces 12 and 13 vibrates in the left-right direction shown in FIG. 1, the vibrating pieces 20a and 20b receive Coriolis force corresponding to the angular velocity of the vehicle and vibrate in the front-rear direction.

The detecting piezoelectric element 30a is fixed to the rear surface of the vibrating piece 20a with one electrode thereof, and the vibration of the vibrating piece 20a is detected as an angular velocity vibration voltage by its piezoelectric conversion action. On the other hand, the detection piezoelectric element 30b is fixed to the rear surface of the vibrating piece 20b by one of the electrodes,
The vibration of the vibrating piece 20b is detected as an angular velocity oscillating voltage by the piezoelectric conversion action. Both piezoelectric elements 30a, 30
The electrodes b are connected to each other at their respective other electrodes to form a common terminal, and the angular velocity oscillating voltage is output from the common terminal. However, the various characteristics of the piezoelectric elements 30a and 30b are substantially the same including the temperature characteristics. The characteristics of both piezoelectric elements 30a and 30b are substantially the same as the characteristics of both piezoelectric elements 15a and 15b described above.

Next, the structure of the signal processing circuit E will be described. The signal processing circuit E includes a self-excited oscillation circuit 40 connected to both vibration reference piezoelectric elements 15a and 15b. This self-excited oscillation circuit 40 has an amplifier 41,
This amplifier 41 includes piezoelectric elements 15a, 15a for both vibration reference.
The vibration reference voltage from the common terminal b is amplified and generated as an amplified reference voltage. The phase shift circuit 42 controls the amplified reference voltage from the amplifier 41 so that the phase thereof is shifted by approximately 90 degrees, and is generated as a phase shift control voltage. The amplifier 43 is
The phase shift control voltage from the phase shift circuit 42 is amplified and applied as an amplified phase shift voltage to the other electrodes of the driving piezoelectric elements 14a and 14b to drive the piezoelectric elements 14a and 14b.

The synchronous detection circuit 50 is provided with an amplifier 51, and the amplifier 51 has both detecting piezoelectric elements 30a and 30b.
The angular velocity oscillating voltage from the common terminal is amplified and generated as an amplified oscillating voltage. The comparator 52 is grounded at its inverting input terminal, and the non-inverting input terminal of this comparator 52 is connected to the output terminal of the amplifier 51. Therefore, the comparator 52 generates the comparison voltage at the high level only when the amplified oscillation voltage from the amplifier 51 is higher than the ground level. On the other hand, the comparator 53 is grounded at its inverting input terminal, and the non-inverting input terminal of this comparator 53 is connected to the output terminal of the phase shift circuit 42. Therefore, the comparator 53 generates the comparison voltage at the high level only when the phase shift control voltage from the phase shift circuit 42 is higher than the ground level. The exclusive OR circuit 54 takes the exclusive OR of the comparison voltages from both comparators 52 and 53 and generates the gate voltage.

Low-pass filter 60 (hereinafter, LPF60
Means to remove frequency components other than the low-frequency component (corresponding to the frequency component of angular velocity) in the gate voltage from the exclusive OR circuit 54, and generate only the low-frequency component as a filter voltage. The amplifier 70 amplifies the filter voltage from the LPF 60 and generates it as an angular velocity voltage representing an angular velocity.

In the present embodiment configured as described above,
When the device of the present invention is in the operating state, both driving piezoelectric elements 14a and 14b of the driving element 10 cooperate with the self-excited oscillation circuit 40 to cause the respective piezoelectric conversion actions to cause the both driving vibrating piece 1 to operate.
2 and 13 are driven. Therefore, each of the vibrating bars 12, 13 vibrates in the lateral direction shown in FIG.
The a and 20b are respectively vibrated in the front-back direction. In such a case, when both the vibration reference vibrating pieces 14a and 14b generate a vibration reference voltage from the common terminal thereof due to the vibration of the both vibrating pieces 12 and 13, in the self-excited oscillation circuit 40, the amplifier 41 outputs the same vibration reference voltage. Amplified vibration voltage (hereinafter, amplified vibration voltage V
1), and the phase shift circuit 42 controls the phase of the amplified oscillation voltage to shift the phase by about 90 degrees to generate a phase shift control voltage (hereinafter, referred to as a phase shift control voltage V2). 43 amplifies the same phase shift control voltage to an amplified phase shift voltage (hereinafter, referred to as an amplified phase shift voltage V3) to drive both drive piezoelectric elements 14;
a and 14b. In this way, the vibration reference voltages from both the vibration reference vibrating pieces 14a and 14b are returned to the driving vibrating pieces 14a and 14b by shifting their phases by approximately 90 degrees, so that the detection device main body S is driven. The element 10 is maintained in a resonance state at a predetermined resonance frequency.

In such a state, for example, when the vehicle is rotating counterclockwise due to its traveling, both the detecting piezoelectric elements 30a and 30b are connected to the two vibrating bars 2 from their common terminals.
When the angular velocity oscillating voltage is generated due to the vibrations of 0a and 20b, the amplifier 51 in the synchronous detection circuit 50 amplifies the same angular velocity oscillating voltage (hereinafter, the amplified oscillating voltage V4 =
Amplify to V41). Then, the amplified oscillation voltage V41
Is higher than the ground level, the comparator 52 generates a comparison voltage at a high level (hereinafter referred to as comparison voltage V6 = V61). Further, only when the phase shift control voltage V2 from the phase shift circuit 42 is higher than the ground level, the comparator 53 is at the high level and the comparison voltage (hereinafter, the comparison voltage V5
Is called). Then, the exclusive OR circuit 54
Generates the gate voltage (hereinafter referred to as gate voltage V7 = V71) by taking the exclusive OR of the comparison voltage V61 from the comparator 52 and the comparison voltage V5 from the comparator 53. Then, the LPF 60 generates a low frequency component of the gate voltage V71 from the exclusive OR circuit 54 as a filter voltage (hereinafter, referred to as filter voltage V8 = V81), and the amplifier 70 outputs the filter voltage V81 from the LPF 60 to the angular velocity voltage. (Hereinafter, it is referred to as angular velocity voltage V9 = V91) and output.

On the other hand, when the vehicle is rotating to the right, the piezoelectric elements for detection 30a and 30b are connected from their common terminals.
When the angular velocity oscillating voltage is generated in accordance with the vibration of both the vibrating bars 20a and 20b, the amplifier 51 amplifies the angular velocity oscillating voltage to an amplified oscillating voltage (hereinafter referred to as amplified oscillating voltage V4 = V42). Then, the comparator 52 generates the comparison voltage (hereinafter, referred to as comparison voltage V6 = V62) at the high level only when the amplified oscillation voltage V42 from the amplifier 51 is higher than the ground level. Further, the comparator 53 generates the comparison voltage V5 at the high level only when the phase shift control voltage V2 from the phase shift circuit 42 is higher than the ground level. Then, the exclusive OR circuit 54 takes the exclusive OR of the comparison voltage V62 from the comparator 52 and the comparison voltage V5 from the comparator 53 to obtain the gate voltage (hereinafter referred to as the gate voltage V7.
= V72) is generated. Then, the LPF 60 generates a low frequency component of the gate voltage V72 from the exclusive OR circuit 54 as a filter voltage (hereinafter, referred to as filter voltage V8 = V82). Then, the amplifier 70
The filter voltage V82 from 0 is amplified to an angular velocity voltage (hereinafter referred to as angular velocity voltage V9 = V92) and output.

However, when the vehicle is stationary,
An offset voltage generated due to the force Fa = mα acting on each of the vibrating bars 20a and 20b due to a deviation from a right angle between each of the vibrating bars 12 and 13 and each of the vibrating bars 20a and 20b is amplified by the amplifier 51. The voltage is output as VOFF.
Therefore, when the vehicle rotates counterclockwise, the amplified oscillating voltage V41
Of the amplified oscillating voltage corresponding to the angular velocity of the vehicle (hereinafter referred to as angular velocity ω) (hereinafter, the amplified oscillating voltage Vω = Vω1
) And an offset voltage VOFF. On the other hand, when the vehicle is rotating to the right, the amplified oscillating voltage V42 corresponds to the amplified oscillating voltage corresponding to the angular velocity ω (hereinafter, the amplified oscillating voltage Vω = V
ω2) and the offset voltage VOFF. In addition, F
When a = mα, the symbol α represents the vibration acceleration of each of the vibrating bars 20a and 20b, and the symbol m represents both the vibrating bars 20a and 20b.
It represents the mass of 0b.

By the way, when the predetermined resonance frequency of the drive element 10 of the above-mentioned detection apparatus main body S is Ω, its vibration amplitude L is expressed by the following equation 1.

[0020]

## EQU1 ## L = Asin (Ωt) However, in this Equation 1, the symbol A indicates both vibrating bars 20a, 2
0b represents the maximum value of the vibration amplitude in the left-right direction in FIG. Further, it is proportional to the detection output of both the vibration reference piezoelectric elements 15a and 15b for detecting the vibration amplitude L, that is, the amplified vibration voltage V1 which is the amplified output of the amplifier 41. In addition, the drive element 10
The vibration velocity Vs of is expressed by the following equation 2 by differentiating the equation 1 with respect to time t.

[0021]

## EQU00002 ## Vs = A.OMEGA.cos (.OMEGA.t) Further, in relation to the angular velocity .omega. Of the vehicle, the Coriolis force F.omega.

[0022]

Therefore, the phase of the Coriolis force Fω becomes equal to the phase of the amplified oscillating voltage Vω1 or Vω2 in the amplified oscillating voltage from the amplifier 51. Fω = 2mω × Vs Further, the phase of the Coriolis force Fω is also equal to the phase of the phase shift control voltage V2 from the phase circuit 42.

The vibration acceleration α is expressed by the following Expression 4 by differentiating Expression 2 with respect to time t.

[0024]

Equation 4] α = -AΩ ² sin (Ωt) Thus, the phase of the vibration acceleration alpha is equal to the above-mentioned offset voltage VOFF phase.

FIG. 2 shows the above relationship as a vector display. According to this, when the vehicle is stationary, the vector value of the amplified reference voltage V1 and the vector value of the offset voltage VOFF have the same phase. Further, when the vehicle rotates to the left, the vector value of the amplified oscillating voltage V41 is given by the vector sum of the vector value of the amplified oscillating voltage Vω1 and the offset voltage VOFF. On the other hand, when the vehicle is rotating to the right, the vector value of the amplified vibration voltage V42 is equal to the amplified vibration voltage V42.
It is given by the vector sum of the vector value of ω2 and the offset voltage VOFF. In such a case, the vector value of the amplified oscillating voltage V41 is shifted from the vector value of the offset voltage VOFF to the left side in the figure by the phase angle θa, while the vector value of the amplified oscillating voltage V42 is greater than the vector value of the offset voltage VOFF. Only the phase angle θb is shifted to the right side in FIG.

Now, the grounds for configuring the synchronous detection circuit 50 as described above will be described. When only the amplitude is considered in the above-described equations 1 to 4, the offset voltage VOFF and the amplified oscillation voltages Vω1 and Vω2 are proportional to the oscillation amplitude L (see the equation 1) of the drive element 10 of the detection apparatus main body S. .. Therefore, if the amplification reference voltage V1 corresponding to the vibration amplitude L in FIG. 2 fluctuates X times, the offset voltage VOFF
Also, the amplified oscillation voltages Vω1 and Vω2 also fluctuate X times. This means that even if the vibration amplitude L changes, the phase angles θa and θb
Means unchanged. In other words, the sensitivity to the angular velocity ω does not change even if the vibration amplitude L changes. Therefore, even if the amplitude of the offset voltage VOFF fluctuates, the final offset output does not fluctuate because only the phase angle is detected by digitization. Based on this ground, the configuration of the synchronous detection circuit 50 is as described above. The phase angles θa and θb are represented by the following equations 5 and 6, respectively.

[0027]

[Formula 5] θa = tan ^-1 (Vω1 / VOFF)

[0028]

[Mathematical formula-see original document] θb = tan ^-1 (Vω2 / VOFF) Further, the above-mentioned relationship is shown in FIGS. 3 (A) to (D) and FIG. 4 (A).
~ (H) is shown in waveform form in the time chart of FIG.
As shown in (A) and (B), when the phase shift control voltage V2 is phase-shifted by 90 degrees from the amplification reference voltage V1, the offset voltage VOFF is equal to that shown in FIG.
The waveform changes as shown by the solid line in (C). Further, when the vehicle is rotating to the left, the amplified vibration voltage Vω1 changes in the waveform shown by the one-dot chain line in FIG. 3C, while when the vehicle is rotating to the right, the amplified vibration voltage Vω2 is changed to the waveform shown in FIG. ) Changes with the waveform shown by the broken line.

Therefore, when the vehicle is stationary, the amplified vibration voltage V4 is specified only by the offset voltage VOFF.
It changes with the waveform shown by the solid line in (D). Further, when the vehicle is rotating to the left, it is identified as the amplified oscillating voltage V41 by combining the offset voltage VOFF and the amplified oscillating voltage Vω1 in FIG. 3C, and the phase angle is represented by the waveform shown by the one-dot chain line in FIG. 3D. θ
It shifts by a, and on the other hand, when the vehicle is turning to the right,
Offset voltage VOFF and amplified oscillation voltage Vω2 in FIG.
Is identified as the amplified oscillating voltage V42 by the combination with
The waveform shown by the broken line in (D) changes with a phase angle θb.

Further, the comparison voltage V5 output by the comparator 53 comparing the phase control voltage from the phase shift circuit 42 with the ground level changes as a digital signal having the waveform shown in FIG. 4 (A). The comparison voltage V6 output by the comparator 52 by comparing the amplified oscillating voltage V4 from the amplifier 51 with the ground level is V4 = VOFF when the vehicle is stationary, and the comparison voltage V6 is set as the comparison voltage V6OFF in FIG. 4 (B). Digitally changes so as to have a waveform shown by. Further, the comparison voltage V6 is set as a comparison voltage V61 based on V4 = V41 when the vehicle is rotating counterclockwise as shown in FIG.
It changes digitally so as to have the waveform shown in (C), while on the other hand, when the vehicle is rotating to the right, it has the waveform shown in FIG. 4D as the comparison voltage V62 under V4 = V42. Changes digitally.

Further, the gate voltage V7, which is the exclusive OR output of the exclusive OR circuit 54 for the respective comparison voltages from the two comparators 52 and 53, is set as the gate voltage V7OFF when the vehicle is stationary as shown in FIG. Digitally changes so as to have a waveform shown by. Also, the gate voltage V7 digitally changes as the gate voltage V71 has a waveform shown in FIG. 4 (F) when the vehicle rotates to the left, while the gate voltage V7 changes when the vehicle rotates to the right. The voltage V72 is digitally changed so as to have the waveform shown in FIG. In other words, the gate voltage V71 or V72 is formed as a voltage having a different duty with respect to the gate voltage V7OFF. Therefore, when the filter voltage V8 output by the LPF 60 based on the gate voltage from the exclusive OR circuit 54 is amplified by the amplifier 70, the angular velocity voltage V9 output from the amplifier 70 is the angular velocity voltage V9OFF when the vehicle is stationary. As a result, the DC level shown by the solid line in FIG. Further, the angular velocity voltage V9 has a DC level indicated by a broken line in FIG. 4 (H) as the angular velocity voltage V91 corresponding to the angular velocity ω at that time when the vehicle rotates to the left, while the angular velocity voltage V9 when the vehicle rotates to the right. , As the angular velocity voltage V92 corresponding to the angular velocity ω at that time.
In (H), it has a direct current level shown by a chain line.

As described above, in the present embodiment, the synchronous detection circuit 50 uses both comparators 52 and 53 and the exclusive OR circuit 54 as main constituent elements to detect only the phase difference regardless of the amplitude. Since synchronous detection is performed by this, fluctuations in offset output and fluctuations in sensitivity due to temperature of each piezoelectric element are ensured while ensuring simplification and cost reduction of the electric circuit configuration of this type of vibration type angular velocity detection circuit. You can lose it.

Next, FIG. 5 shows a modification of the above embodiment.
This will be described with reference to (A). Each phase angle θa, θb described above
Has a non-linear characteristic with respect to the angular velocity ω, as can be seen from Equations 5 and 6. In the synchronous detection circuit of the vibration type angular velocity detection device described in the prior art of this specification, only the vibration amplification voltage Vω1 or Vω2 is rectified by the rectification circuit, and the offset voltage VOFF is canceled, so the rectification output of the rectification circuit. Is highly linear. Therefore, if a phase variation of the offset voltage VOFF occurs, it will cause an error.
Studies have been made to reduce the offset voltage VOFF.

However, in the above embodiment, the synchronous detection circuit 50 is used.
In the synchronous detection method using the exclusive OR circuit 54 of No. 5, since only the phase angle shown in Formula 5 or Formula 6 is detected without depending on the rectifier circuit or the like, the offset voltage VOF
F is actively generated, and tan in equations 5 and 6
^The linearity with respect to the angular velocity ω can be improved by using only the small terms of ⁻¹ (Vω1 / VOFF) and tan ⁻¹ (Vω2 / VOFF). In this case, in order to suppress the non-linearity to 1 (%), (Vω1 / VOF
F) and (Vω2 / VOFF) must be less than 0.28. For example, the input range of the angular velocity ω is ± 50 (degree / se
In the case of c), if VOFF is made larger than the value corresponding to 179 (degrees / sec), the non-linearity can be reduced to 1 (%) or less. At this time, the phase angle θ is less than 15.6 (degrees).

From this viewpoint, the present modification is proposed. This modification is characterized in that the offset adjusting circuit 90 is connected between the amplifiers 41 and 51 and the comparator 52 described in the above embodiment. The offset adjusting circuit 90 is an amplifier circuit 91.
The amplifier circuit 91 has a phase inverting amplifier 9
1a and both resistors 91b and 91c cause an offset voltage V
The oscillation reference voltage V1 from the amplifier 41 having the same phase as OFF is phase-inverted and amplified and output as an inverted amplified voltage V10. Also,
The amplifier circuit 91 has a variable resistor 91d, and this variable resistor 91d adjusts the ratio between the amplified reference voltage V1 from the amplifier 41 and the inverted amplified voltage V10 from the phase inverting amplifier 91a and outputs it as an adjusted ratio voltage. ..

Further, the offset adjusting circuit 90 includes an adder 9
2, the adder 92 adds the amplified oscillating voltage from the amplifier 51 and the adjustment ratio voltage from the variable resistor 91d to generate an added voltage. The amplifier 93 amplifies the added voltage from the adder 92 and applies it to the non-inverting input terminal of the comparator 52 as the added amplified voltage V11. Therefore, the comparator 52 compares the added amplified voltage V11 from the amplifier 93 with the ground level, and generates it as a comparison voltage, unlike the above-described embodiment.

In this modified example having such a configuration, the phase inverting amplifier 91a causes the amplification reference voltage V from the amplifier 41 to be applied.
When 1 is output as the inverted amplified voltage V10, the variable resistor 91
d generates an adjustment ratio voltage based on the amplification reference voltage V1 from the amplifier 41 and the inverting amplification voltage V10 from the phase inverting amplifier 91a, and the adder 92 produces the amplification oscillation voltage V4 from the amplifier 51 and the adjustment ratio from the variable resistor 91a. The added voltage is generated based on the voltage, the amplifier 93 generates the added amplified voltage V11 based on the added voltage from the adder 92, and the comparator 52 compares the added amplified voltage V11 from the amplifier 93 with the ground level to obtain a comparison voltage. V6 is generated. In such a case, since the offset voltage VOFF is positively generated while ensuring accurate linearity as described above, the exclusive OR circuit 5
The exclusive OR processing by 4 can be properly performed. Other functions and effects are similar to those of the above embodiment.

Next, another modification of the above embodiment will be described with reference to FIG. 5B. Although this other modification is proposed from the same viewpoint as the above modification, In the modified example, the vibrating piece 20 is arranged such that the deviation angle between the plate width directions of the vibrating pieces 12 and 20a in the detection device main body S described in the above embodiment is an angle β smaller than 90 degrees.
a is coaxially extended from the vibrating piece 12, and the vibrating piece 20b is coaxially extended from the vibrating piece 13 so that the deviation angle between the plate width directions of both the vibrating pieces 13 and 20b is the angle β. There is a feature in that configuration. The other structure is similar to that of the above embodiment.

In this modified example having such a configuration,
Since the offset oscillation voltage VOFF can be positively included in the amplified oscillating voltage V4 from the amplifier 51 based on the deviation angle β as described above, the exclusive OR processing of the exclusive OR circuit 54 is the same as that of the modification. Can be realized properly. Other functions and effects are similar to those of the above embodiment.

In the above embodiment, the amplified phase shift voltage V3 from the amplifier 43 to the driving piezoelectric elements 14a and 14b has a sinusoidal waveform, but the invention is not limited to this. Since it has a characteristic as a kind of bandpass filter, the amplified phase shift voltage V3 may have a rectangular wave waveform. In such a case, the vibration amplitude fluctuates due to temperature and the like depending on the characteristics of the driving piezoelectric elements 14a and 14b, but such a phenomenon can be effectively eliminated by using the synchronous detection circuit according to the present invention. ..

Further, in implementing the present invention, each vibrating piece of the detecting device main body S may be formed into a prism shape or a triangular prism shape.

Further, in carrying out the present invention, the processing such as a microcomputer may be carried out in carrying out the exclusive OR processing after the digital processing described in the above embodiment.

Further, the present invention is not limited to vehicles, but the present invention may be applied to the detection of angular velocities of ships, aircrafts and other various moving bodies.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example in which the output of each main element of FIG. 1 is displayed as a vector.

FIG. 3 is a time chart showing a part of output waveforms in each main element of FIG.

FIG. 4 is a time chart showing output waveforms of the remaining elements in each main element of FIG.

FIG. 5 is a circuit diagram of a main part showing a modified example of the embodiment and a partial plan view showing another modified example of the embodiment.

[Explanation of symbols]

E ... Signal processing circuit, S ... Detection device main body, 10 ... Driving element, 12, 13, 20a, 20b ... Vibrating piece, 14a, 1
4b, 15a, 15b, 30a, 30b ... Piezoelectric element, 4
2 ... Phase shift circuit, 50 ... Synchronous detection circuit, 52, 53 ... Comparator, 54 ... Exclusive OR circuit.

Claims (1)

[Claims] 1. A vibrating member movably provided on a part of a moving body, a driving piezoelectric element fixed to the vibrating member and driving the vibrating member to vibrate in one direction, and the vibrating member. A detection piezoelectric element that is fixed to the vibration member and that detects a vibration generated in the vibrating member in a direction intersecting the one direction according to the angular velocity of the moving body to generate an angular velocity vibration detection signal; A piezoelectric element for vibration reference that has the same characteristics as the piezoelectric element and that detects the vibration of the vibration member and generates a vibration reference signal; and a phase control by controlling the phase of the vibration reference signal so that it shifts the phase by approximately 90 degrees. Phase control means for giving the driving piezoelectric element to drive it as an output, and a synchronous detector for synchronously detecting the angular velocity vibration detection signal based on the phase shift control output and generating it as an output signal representing the angular velocity. A vibration type angular velocity detecting device comprising: a first digitizing processing means for digitizing the phase shift control output; a second digitizing processing means for digitizing the angular velocity vibration detection signal; The synchronous detection means is constituted by exclusive OR processing means for performing exclusive OR processing of both digitized processing outputs from the second digitization processing means and generating as the output signal. Vibration type angular velocity detector.