JP2000283764A - Angular velocity detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and cost of an angular velocity detector, improve the temp. characteristic and prevent the characteristic change due to aging. SOLUTION: A tuning fork oscillator 1 is of a piezoelectric single crystal, an oscillator circuit 3 causes its driving arm 101 to oscillate at a resonance frequency f0 in a specified direction, and a detecting arm 102 also oscillates in the same direction synchronously with the driving arm and forcedly oscillates at the same frequency f0 in a direction perpendicular to that oscillating direction due to a Coriolis force with rotation. First detecting electrodes 15, 18 of its detecting arm are connected to a ground wire 57, a positive input terminal of an operational amplifier 33 constituting a detector circuit 6 is connected to ground wire 57, and second detecting electrodes 16, 17 are connected to a negative input terminal which is connected to an according to terminal through a feed back resistor 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detector using a tuning fork vibrator or a three-fork vibrator made of a piezoelectric single crystal.

[0002]

2. Description of the Related Art Conventionally, an angular velocity detecting device using a mechanical rotary gyroscope has been used as an inertial navigation device for airplanes and ships. Although the mechanical rotary gyroscope has high stability and high performance, it has disadvantages in that the device is large, expensive, and has a short life.

In recent years, as an alternative to the mechanical rotary gyroscope, a vibrating body has been excited by using a polycrystalline piezoelectric element which is a barium titanate-lead zirconate-based piezoelectric ceramic, and the angular velocity of rotation has been reduced. Practical use of a small vibratory gyroscope that detects a voltage generated by vibration excited by Coriolis force with a piezoelectric element has been advanced. For example, Japanese Patent Laying-Open No. 3-10112 proposes an angular velocity detecting device using a gyroscope using a tuning fork vibrator.

[0004] Therefore, a conventional angular velocity detecting device using a gyroscope will be briefly described. JP-A-3-101
The angular velocity detecting device disclosed in Japanese Patent Publication No. 12 is provided with a driving piezoelectric element on a tuning fork vibrator having a central connecting portion,
The central connecting portion extending from the base of the tuning fork vibrator is supported by a tubular member also serving as a case via a hinge provided in a direction perpendicular to the connecting portion.

By applying an AC voltage to the driving piezoelectric element, the tuning fork vibrator is vibrated, and the hinge portion bends and vibrates while being deformed into an S shape by Coriolis force accompanying rotation of the tubular member. A voltage is generated in the detection piezoelectric element provided in the hinge portion, and the generated voltage is detected by a voltage detection circuit to determine the angular velocity.

FIG. 26 shows a voltage detecting circuit using the piezoelectric element for detecting the angular velocity. In FIG. 26, a piezoelectric element 80 for detection is equivalent to a capacitor 86
(Capacitance value C3), voltage source 84 and resistor 85 (resistance value R5)
And can be represented by The piezoelectric element 80 is connected between the plus input terminal of the operational amplifier 83 and the ground, and a resistor 87 (resistance R3) is connected between the minus input terminal of the operational amplifier 83 and the ground, and the minus input terminal and the output terminal. And a resistor 88 (resistance value R4) is connected between
A voltage detection circuit is configured by an amplifier circuit.

Therefore, the voltage Vi generated by the piezoelectric element 80 is calculated by the voltage detection circuit as Vo = (1 + R4
/ R3) The voltage is amplified to Vi, and an output voltage Vo capable of signal processing is obtained. The angular velocity is obtained by synchronously detecting the output voltage Vo at the reference frequency of the tuning fork vibrator.

In the piezoelectric element made of a polycrystalline material such as piezoelectric ceramics used in this conventional example, the equivalent resistance R5 indicated by a resistor 85 in FIG. 26 is a low value of 1 KΩ or less. It has a property close to that of a constant voltage source. When receiving an angular velocity that rotates once per second, the piezoelectric element 80
Is several hundred microvolts to several millivolts.

FIG. 27 is a graph showing theoretical limits of voltage measurement. The noise voltage (V) increases linearly in proportion to the source resistance of the power supply, ie, the equivalent resistance (Ω) or impedance (Ω). To do.

The noise voltage straight line 90 and the noise voltage straight line 91 on the graph are substantially parallel, and the region above the noise voltage straight line 90 is the region where the voltage can be detected by a simple amplifier. The area above the straight line 91 is an area where voltage cannot be detected unless a precise measuring instrument such as an electrometer is used. The region where the generated voltage Vi is below the straight line 91 is a region where the voltage cannot theoretically be detected.

As described above, as a piezoelectric element,
Piezoelectric ceramics are used, and the source resistance of the piezoelectric ceramic, that is, the equivalent resistance or equivalent electric impedance is 1 KΩ or less. The noise voltage level of the noise voltage line 90 near this resistance value is about 1 microV.
However, the generated voltage of the piezoelectric ceramic is several hundred micro V
To several millivolts. Therefore, an angular velocity detecting device using a piezoelectric ceramic-based piezoelectric element for detection can obtain an angular velocity using a relatively simple voltage detection circuit as shown in FIG.

[0012]

However, such a conventional angular velocity detecting device has the following problems. First, the tuning fork vibrator has a complicated shape due to a structure in which a hinge portion is provided at right angles to a central connecting portion extending from the base portion and is supported by a tubular member via the hinge portion.

Further, it is necessary to bond a plurality of piezoelectric elements to the metal tuning fork vibrator and the hinge part, which not only complicates the assembling process but also increases the overall shape, making it difficult to reduce the cost. . In addition, since a metal tuning fork vibrator is used, the temperature characteristics are not good, and aging (aging) occurs.
There is a problem that the characteristics change.

Second, when a single crystal material having a source resistance (equivalent resistance) or a high equivalent electric impedance of 10 KΩ or more is used in place of the piezoelectric ceramic as the detecting element, the angular velocity which rotates once per second is received. When
The voltage generated by the piezoelectric distortion effect is several micro volts.

As can be seen from the noise voltage straight line 90 in FIG. 27, when the source resistance (equivalent resistance) or the equivalent electric impedance becomes 10 KΩ or more, the noise voltage of the detecting element increases to 1 μV or more, Therefore, the conventional voltage detection circuit as shown in FIG. 26 cannot detect the angular velocity, and there is a problem that practical application becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide an angular velocity detecting device which can be reduced in size and cost, has good temperature characteristics, and has no characteristic change due to aging. Aim. Another object of the present invention is to provide an angular velocity detecting device capable of detecting angular velocity even when a piezoelectric single crystal is used, in which a source resistance, that is, an equivalent resistance or an equivalent electric impedance shows a high value of 10 KΩ or more as a detecting element. And

[0017]

According to the present invention, in order to achieve the above object, an angular velocity detecting device is constituted as follows. That is, the angular velocity detecting device according to the present invention includes a tuning fork vibrator, and the tuning fork vibrator is made of a piezoelectric single crystal,
A plurality of drive electrodes are provided, and a drive arm that self-oscillates at a resonance frequency in a predetermined direction (X or Z direction), and first and second detection electrodes are provided, and are synchronized with the drive arm. And vibrates in the same direction (X or Z direction) as the drive arm, and is forcibly forced by the Coriolis force accompanying rotation at the same frequency as the resonance frequency of the drive arm and orthogonal to the direction of the self-excited vibration ( A detection arm that vibrates in the (Z or X direction), and a base provided with the drive arm and the detection arm provided in parallel with each other.

Further, an oscillation circuit is connected to each drive electrode of the drive arm of the tuning fork vibrator to oscillate the drive arm self-excited, and the oscillation circuit for detecting the above by the Coriolis force caused by the rotation of the tuning fork vibrator. A detection circuit having an operational amplifier for detecting the vibration of the arm.

The first detection electrode of the detection arm is connected to a ground line, and the detection circuit is
A positive input terminal of the operational amplifier is connected to the ground line, a second detection electrode of the detection arm is connected to a negative input terminal of the operational amplifier, and a negative input terminal and an output terminal of the operational amplifier are further connected. Are connected via a feedback resistor.

Further, the detection circuit is connected to the ground line through a parallel circuit of a resistor and a capacitor, and a positive input terminal of the operational amplifier is connected to the second detection electrode of the detection arm and the operational amplifier. A negative input terminal may be connected, and a negative input terminal and an output terminal of the operational amplifier may be connected via a feedback resistor.

Alternatively, the detection circuit is connected to the ground line through a resistor at a positive input terminal of the operational amplifier, and a second detection electrode of the detection arm is connected to a negative input terminal of the operational amplifier. Preferably, the operational amplifier is connected by connecting the minus input terminal and the output terminal of the operational amplifier via a feedback resistor, and the output terminal and the plus input terminal of the operational amplifier are connected by an integrating circuit.

In the angular velocity detecting device according to the present invention, a three-forked vibrator configured as follows can be used in place of the tuning fork vibrator. The three-forked oscillator is made of a piezoelectric single crystal having three arms including at least one drive arm and at least one detection arm, and a base having the three arms provided in parallel with each other. , The driving arm has a plurality of driving electrodes and is arranged in a predetermined direction (X or Z direction).
The detection arm has first and first detection electrodes, and oscillates in the same direction (X or Z direction) as the drive arm in synchronization with the drive arm. The arm vibrates in a direction (Z or X direction) orthogonal to the direction of the self-excited vibration at the same frequency as the resonance frequency of the driving arm due to the Coriolis force caused by the rotation.

As in the case of the above-described angular velocity detecting device, an oscillation circuit is connected to each drive electrode of the drive arm of the three-forked vibrator to self-oscillate the drive arm. A detection circuit having an operational amplifier for detecting vibration of the detection arm due to Coriolis force caused by rotation. Further, the first detection electrode of the detection arm is connected to a ground line, and the detection circuit is configured in the same manner as any one of the various detection circuits in the angular velocity detection device having the tuning fork vibrator described above. I do.

In these angular velocity detecting devices,
A series circuit of a first resistor and a second resistor is connected between the output terminal of the operational amplifier that forms the detection circuit and the ground line, and the minus input terminal and the output terminal of the operational amplifier are connected to the negative terminal. It is preferable to connect via a feedback resistor and the first resistor.

In these angular velocity detecting devices,
The equivalent resistance or equivalent electrical impedance between the first detection electrode and the second detection electrode of the detection arm is 1
It is desirable that the value be 0 kΩ or more.

Further, the resonance frequency of the self-excited vibration of the drive arm is f0 (Hz), and the resonance frequency of the detection arm in the direction orthogonal to the vibration direction of the self-excited vibration of the drive arm is f1 (Hz). Hz), the value of the detuning frequency Δf = f0−f1 between the resonance frequency f0 (Hz) of the driving arm and the resonance frequency f1 (Hz) of the detection arm is changed from f1 / 1000 to f1. / 10 or -f
It is desirable to be between 1/1000 and -f1 / 10.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an angular velocity detecting device according to the present invention will be described below with reference to the drawings. [First Embodiment: FIGS. 1 to 8] FIG. 1 is a circuit diagram showing an overall configuration of a first embodiment of an angular velocity detecting device according to the present invention, and FIG. 2 is an equivalent circuit of the tuning fork vibrator. FIG. 3 is a circuit diagram for explaining the operation principle of the detection circuit. FIG. 3 is a graph showing frequency versus gain characteristics when the input impedance of the detection circuit is changed.

FIG. 3 and FIG. 4 are a perspective view as seen from the oblique right front side and a perspective view as seen from the oblique right back side showing an example of the appearance of the tuning fork vibrator. FIG. 5 is a diagram showing reactance characteristics with respect to the frequency of the detection arm of the crystal unit in this embodiment. FIG. 6 is a diagram showing frequency versus gain characteristics when the input impedance of the detection circuit is changed.

FIGS. 7 and 8 show the respective signals in FIG. 1 when the tuning fork vibrator of the angular velocity detecting device of the first embodiment receives a clockwise angular velocity and a counterclockwise angular velocity, respectively. FIG. Hereinafter, an angular velocity detecting device according to a first embodiment of the present invention will be described with reference to these drawings.

First, the tuning fork vibrator used in this embodiment will be described with reference to FIGS. The tuning fork vibrator 1 is a crystal vibrator, and is integrally formed from a quartz plate which is a piezoelectric single crystal body by mechanical processing using a wire saw or the like. Further, it can be formed by chemical processing such as etching or ion / track etching. The tuning fork vibrator 1 includes a drive arm 101 and a detection arm 102, and a base 103 provided in parallel with each other. The base 103 is supported by a support member (not shown).

The driving arm 101 is formed in a prism shape.
Driving electrodes 10, 11, 12, 13, and 14 are formed on each surface by vacuum deposition of a metal film or the like. The opposing two surfaces of the driving electrodes 10 and 11 are connected by a connecting portion L6, and furthermore, a lead portion L1 formed on the base portion 103.
To the terminal T1. The other two opposing driving electrodes 12, 13 and 14 are also connected by a connecting portion L 7, and furthermore, a lead portion L formed on the base 103.
2 is connected to the terminal T2.

The detection arm 102 is also formed in a prism shape.
The electrodes 15, 16, 1 for detection are placed on the corner surfaces including the ridges.
7, 18 are formed by vacuum deposition of a metal film or the like.
The first detection electrodes 15 and 18 facing each other in one diagonal direction are connected by a connection portion L9, and further connected to a terminal T4 by a lead portion L4 formed on the base portion 103. In addition, the other diagonally opposed second detection electrodes 16 and 17 are also connected by a connection portion L8,
Further, it is connected to a terminal T3 by a lead portion L3 formed on the base 103. Terminals T1 to T4 are all base 10
3 is provided below the front surface.

Here, the first embodiment will be described with reference to a circuit diagram showing the entire configuration of FIG. The angular velocity detecting device includes a tuning fork vibrator 1 (FIG. 1 shows only the arrangement of the driving arm 101 and the detecting arm 102 and their respective electrodes in a top view in FIG. 3), and an oscillation circuit. 3, a phase shift circuit 4, a waveform shaping circuit 5, a detection circuit 6, an inversion circuit 7, a detection circuit 8, and a low-pass filter 9.

The oscillating circuit 3 includes operational amplifiers 19 and 20, resistors 21, 23 and 24, and a capacitor 22. Driving electrode 1 formed on driving arm 101 of tuning fork vibrator 1
2, 13, and 14 are connected on the driving arm 101 as described above, and are connected to the minus input terminal of the operational amplifier 19 by the conducting wire 50. In addition, other driving electrodes 10,
11 is also connected on the driving arm 101, and is connected to the output terminal of the operational amplifier 20 by the conducting wire 51.

The positive input terminal of the operational amplifier 19 is connected to the ground line 57, and the negative input terminal is connected to the output terminal via the feedback resistor 21. The output terminal of the operational amplifier 19 is connected to the minus input terminal of the operational amplifier 20 via a capacitor 22 and a resistor 24. The negative input terminal is connected to the output terminal via the resistor 23, and the positive input terminal is connected to the ground line 57.

The operational amplifier 20 and the resistors 23 and 24 constitute an inverted voltage amplifier circuit, and the voltage amplification is set by the ratio of the resistance values of the resistors 23 and 24. Also,
The operational amplifier 19 and the resistor 21 constitute an inverting current amplifying circuit, and convert a current flowing through the driving arm 101 of the tuning fork vibrator 1 into a voltage and feed it back to the operational amplifier 20.

The detection circuit 6 comprises an operational amplifier 33 and a feedback resistor 34. The first detection electrodes 15 and 18 formed on the detection arm 102 of the tuning fork vibrator 1 are connected on the detection arm 102 and are connected to the ground wire 57. Further, the second detection electrodes 16 and 17 formed on the detection arm 102 are also connected on the detection arm 102, and are connected to the minus input terminal of the operational amplifier 33 by the conducting wire 56.

A negative input terminal of the operational amplifier 33 of the detection circuit 6 is connected to an output terminal via a feedback resistor 34. Further, the positive input terminal of the operational amplifier 33 is connected to a ground wire 57 having the same potential as the detection electrodes 18 and 15. Then, a short-circuit current that equivalently short-circuits between the detection electrodes 15 and 18 and the detection electrodes 16 and 17 of the detection arm 102 flows through the feedback resistor 34.

The phase shift circuit 4 comprises an operational amplifier 25 and a resistor 2
6, 27 and 28 and a capacitor 29. The oscillation output signal S1 of the oscillation circuit 3 is connected to the conductor 5 connected to the capacitor 22.
2 and the resistor 26 are input to the minus input terminal of the operational amplifier 25 and the resistor 28 to the positive input terminal of the operational amplifier 25, respectively. The positive input terminal of the operational amplifier 25 is connected to the ground line 57 via the capacitor 29, and the negative input terminal is connected to the output terminal via the resistor 27. The phase shift circuit 4 is an all-pass filter, and can change the phase of the oscillation output signal S1 of the oscillation circuit 3 without changing the amplification degree.

The waveform shaping circuit 5 includes inverters 30 and 31
And a resistor 32. Then, the output signal S2 of the phase shift circuit 4 is input to the input terminal of the inverter 30 via the conductor 53. The input terminal and output terminal of the inverter 30 are connected via a resistor 32, and the output terminal is connected to the input terminal of the inverter 31. Conducting wires 54 and 55 connected to the respective output terminals of the inverters 30 and 31 have detection pulses S having a pulse width of 1 to 1 and having a phase inversion of 180 degrees.
3 and S4 are output.

The inverting circuit 7 comprises an operational amplifier 35 and a resistor 3
6, 37. Then, the detection signal Vo from the detection circuit 6 is input to the minus input terminal of the operational amplifier 35 via the conductor 58 and the resistor 36 of the inversion circuit 7. The negative input terminal of the operational amplifier 35 is connected to an output terminal via a resistor 37, and the positive input terminal is connected to a ground line 57. The inversion circuit 7 inverts the phase of the detection signal (AC voltage) Vo from the detection circuit 6 by 180 degrees without changing the amplification degree and outputs the result.

The detection circuit 8 includes transmission gates 38 and 39. Then, the detection signal V of the detection circuit 6
The signal o is input to the input terminal of the transmission gate 38 via the conductor 58, and the output signal V1 of the inverting circuit 7 is input to the input terminal of the transmission gate 39 via the conductor 59.

A detection pulse S 3 output from the inverter 30 of the waveform shaping circuit 5 is applied to the inversion control terminal of the transmission gate 38 and the non-inversion control terminal of the transmission gate 39 via the conductor 54. The detection pulse S4 output from the inverter 31 is
The voltage is applied to the non-inverting control terminal of the transmission gate 38 and the inverting control terminal of the transmission gate 39 by the conducting wire 55. Further, the output terminals of the transmission gates 38 and 39 are connected to the conductor 60.

The low-pass filter 9 includes an operational amplifier 40, resistors 41 and 42, and capacitors 43 and 44. And
The output signal V of each transmission gate of the detection circuit 8
The reference numeral 2 designates the resistances 41 and 4 of the low-pass filter 9 by the conducting wire 60.
2 to the plus input terminal of the operational amplifier 40. The positive input terminal of the operational amplifier 40 is a capacitor 44
Is connected to the ground line 57 via the.

The connection point between the resistors 41 and 42 is connected to the minus input terminal and the output terminal 61 of the operational amplifier 40 via the capacitor 43. This low-pass filter 9 is
This is a voltage source type filter which is a kind of active filter, and the high frequency band is attenuated at 40 dB / dec.

Next, the operation of the angular velocity detecting device thus configured will be described. The oscillation circuit 3 is a positive feedback oscillator including an operational amplifier 20 which is an inverting voltage amplifier circuit and an operational amplifier 19 which is an inverting current amplifier circuit, and has a loop for driving the tuning fork vibrator 1 as a frequency selecting element. The arm 101 is arranged, oscillates at a frequency f0 (Hz) near the series resonance frequency, and the driving arm 101 vibrates in the plane in the X direction in FIG.

The X direction shown in FIG. 3 is substantially parallel to the electric axis of the crystal forming the tuning fork resonator 1, the Y direction is substantially parallel to the mechanical axis of the crystal, and the Z direction is substantially parallel to the optical axis of the crystal. It may be rotated about 1 to 10 degrees to obtain characteristics.

An operational amplifier 19 which is an inverting current amplifier circuit
Converts an AC current flowing through the drive arm 101 of the tuning fork vibrator 1 into an AC voltage and outputs the AC voltage. That is, the signal voltage S1 having the oscillation frequency f0 (Hz) is generated with the sine waveforms shown in FIGS.

The detection arm 102 also oscillates in-plane in the X direction in synchronization with the drive arm 101 of the tuning fork vibrator 1. At this time, when the tuning fork vibrator 1 is rotated at an angular velocity ω whose vector axis is parallel to the Y direction, a Coriolis force F proportional to the angular velocity ω acts in the Z direction perpendicular to the in-plane vibration. The Coriolis force F can be expressed as follows. F = 2 ・ m ・ ω ・ V

Here, m is the equivalent mass of the driving arm 101 or the detecting arm 102, and V is the frequency f0 (Hz).
Is the speed of vibration. The Coriolis force F excites out-of-plane vibration having the same frequency f0 (Hz) as in-plane vibration. Due to this vibration, the detection electrode 1 of the detection arm 102 is
Positive charges and negative charges are generated alternately at 6, 17 and 15, 18.

Therefore, in accordance with the Coriolis force F received by the detection arm 102, positive charges are applied to the detection electrodes 16 and 17 of the detection arm 102, and the detection electrodes 15 and
A state in which a negative charge is generated in 18 and a state in which a negative charge is generated in the detection electrodes 16 and 17 and a state where a positive charge is generated in the detection electrodes 15 and 18 occur alternately.

Here, the detection arm 10 of the tuning fork vibrator 1
2 and the operation of the detection circuit 6 will be described in detail with reference to FIG. 2 indicate the driving arm 101 and the detecting arm 1 of the tuning fork vibrator 1 by the Coriolis force F.
02 indicates the mechanical constant when out-of-plane vibration at the oscillation frequency f0 (Hz) is replaced by an electrical equivalent circuit.

This equivalent circuit includes a parallel equivalent capacitance 62 (capacitance value C0) based on the inter-electrode capacitance and shape dimensions between the detection electrodes 16 and 17 and the detection electrodes 15 and 18, and an equivalent inductance 63 (inductance value). L1) and equivalent capacity 64
This is equivalent to a circuit in which a (capacitance value C1) and a series circuit of an equivalent resistor 65 (resistance value R1) are provided in parallel.

Assuming that the mechanical equivalent mass of the tuning fork vibrator 1 is m, the equivalent compliance is c, the equivalent viscous drag coefficient is r, and the force coefficient which is a proportional constant is A, L1 = m / A ² C1 = cA ² R1 = R / A ² .

The equivalent electric impedance Z1 viewed from the parallel equivalent capacitance 62 is given by Z1 = R1 +
j (2πf · L1-1 / 2πf · Co), and the reactance X becomes X1 = 2πf · L1-1 / 2πf · C0, and the reactance X1 changes with respect to a change in frequency.
As shown in FIG. 5, it becomes 0 at the resonance frequency f1 (Hz), and tends to increase almost in proportion to the frequency.

As a specific embodiment of the tuning fork vibrator, an example in which only the thickness of a quartz crystal vibrator for a watch is changed will be described. The width of the driving arm 101 and the detecting arm 102 in the in-plane vibration direction (X direction in FIG. 3) of the tuning fork vibrator 1 by the crystal vibrator is set to 59.
0 μm, the length of each arm is 3660 μm, the total length of the tuning fork vibrator 1 is 5900 μm, and the resonance frequency f1 (Hz) of out-of-plane vibration is the resonance frequency f0 (Hz) of in-plane vibration.
Is set to 700 μm in order to approach

[0057] Equivalent circuit constants when the tuning fork oscillator (crystal oscillator) to out-of-plane vibrations in the Z direction of FIG. 3 in a vacuum, the equivalent resistance R1 = 20 k [Omega, the equivalent capacitance C1 = 1 × 10- ¹⁵
F, the equivalent inductance L1 = 23.1 × 10 ³ H, and the resonance frequency f1 of the out-of-plane vibration is 33 kHz. In the atmosphere or an inert gas at 1 atm, the equivalent resistance is increased about 10 times to about R1 = 200 kΩ.

The frequency of the difference between the resonance frequency f0 of the in-plane vibration and the resonance frequency f1 of the out-of-plane vibration is represented by the detuning frequency Δf = f0−
f1. With the resonance frequency f1 (Hz) of the out-of-plane vibration kept constant, the resonance frequency f0 of the in-plane vibration is changed by electrically adding a passive element to the oscillation circuit 3 of FIG.

Actually, the resonance frequency f0 (H
z) is constant, and the equivalent compliance is inversely proportional to the length of a support member (not shown) that supports the base 103 of the tuning fork vibrator 1 shown in FIGS. 3 and 4, so that the length of the support member is changed. It is also possible to change the resonance frequency f1 (Hz) of the out-of-plane vibration. Here, while the resonance frequency f1 (Hz) of the out-of-plane vibration is kept constant, the resonance frequency f0 (Hz) of the in-plane vibration is changed by using a passive element, and the change in the reactance X1 due to this is examined. To

When f0 = 29.7 kHz, the detuning frequency is Δf = −f1 / 10, and the reactance at this time is X1 = −1.049 × 10 ⁹ Ω (= −1049).
MΩ). When f0 = 36.3 kHz,
Δf = f1 / 10, and the reactance is X1 = 0.
885 × 10 ⁹ Ω (= 885 MΩ).

When f0 is set to 32.967 kHz,
The detuning frequency is Δf = −f1 / 1000, and the reactance at this time is X1 = −43 × 10 ⁶ Ω (= −43
MΩ). When f0 = 33.033 kHz, △
f = f1 / 1000, and the reactance is X1 = 4
It becomes 0 × 10 ⁶ Ω (= 40 MΩ).

The equivalent resistance R1 is between 20 kΩ and 200 kΩ, which is very small compared to the reactance X1.
The value of the reactance X1 may be set as the value of the equivalent electric impedance Z1. Accordingly, the detuning frequency Δf is set to f0 centering on f1, and Δf = ± f from Δf = ± f1 / 1000.
It can be seen that the equivalent electric impedance Z1 when changed to 1/10 has a very large value between 40 MΩ and 1 GΩ.

When the detuning frequency Δf is set to ± f1 / 1000 or less, the resonance frequency f0 (Hz) of the in-plane vibration and the resonance frequency f1 (Hz) of the out-of-plane vibration become very close, and the Q value becomes high. The detection arm 102 for a small change in Δf.
Since the speed fluctuation of the signal becomes very large, the detection becomes unstable. Furthermore, out-of-plane vibrations occur even if the angular velocity does not work due to mechanical coupling. Also, the detuning frequency Δf is ± f
When it becomes 1/10 or more, the frequency f0 (Hz) of the in-plane vibration
And the frequency (Hz) of the out-of-plane vibration is too far away, the vibration speed V of the out-of-plane vibration becomes very small, the generated electric charge decreases, and almost no detection output is obtained.

Assuming that the open-loop gain of the operational amplifier 33 is A, the input impedance of the operational amplifier 33 shown in FIG.
A). Since the open loop gain A is 100 dB or more, the input impedance of the operational amplifier 33 becomes very small, and the charges generated in the parallel equivalent capacitance 62 do not flow to the equivalent electric impedance Z1 but almost all flow to the operational amplifier 33. Become.

The parallel equivalent capacitance 6 of the detection electrode of the tuning fork vibrator
One end of the second and the positive input terminal of the operational amplifier 33 are connected to the same ground wire 57. On the other hand, the other end of the parallel equivalent capacitance 62 is connected to the minus input terminal. Therefore,
The negative input terminal of the operational amplifier 33 is
It is short-circuited to have the same potential as the positive input terminal, and both ends of the parallel equivalent capacitance 62 are equivalently short-circuited.
However, the resistance Ri of the input resistor 66 between the minus input terminal and the plus input terminal is very large and almost infinite. Therefore, the equivalent short-circuit current Is is equal to the feedback resistance 3
4 (resistance value Rf), and the lead wire 58 connected to the output terminal
The short-circuit current Is is converted to a voltage, and the output voltage Vo =
-Rf · Is occurs.

The resistance value R of the output resistor 67 of the operational amplifier 33
Since 0 is very small, if the voltage drop in this part is omitted, the conversion coefficient of the current source 68 inside the operational amplifier 33 is r
Then, the voltage increases by r · Is = Rf · Is, and the parallel equivalent capacitance 62 is short-circuited in a closed loop.

FIG. 6 shows that the equivalent electric impedance Z1 is 1 kΩ, 10 kΩ, 100 k with the feedback resistance Rf = 1 MΩ.
FIG. 7 is a diagram showing frequency versus gain characteristics when curves are changed to Ω and 1 MΩ, respectively, as curves 70, 71, 72 and 73.
The resonance frequency of this tuning fork resonator (quartz resonator) 1 is 8 kHz.
From z to about 40 kHz, it can be seen from the diagram that if the equivalent electric impedance Z1 is 10 kΩ or more, a gain that is practically almost satisfactory can be obtained.

Here, since the short-circuit current of the detection electrode of the tuning fork vibrator 1 is as small as several picoamps to several microamps, the operational amplifier 33 is required to have a bias current that is very small on the order of femto-amperes as compared with the input current. For this reason, a low noise FET input operational amplifier or MOS operational amplifier is used. The operation of the detection circuit 6 has been described above, and the operation of the entire angular velocity detection device shown in FIG.
This is performed with reference to the signal waveform diagrams of the respective parts shown in FIGS.

FIG. 7 is a waveform diagram when receiving the rightward angular velocity in the Y-axis direction shown in FIG. The output signal S1 of the oscillation circuit 3 is an AC voltage waveform having a resonance frequency f0 (Hz), and the detection signal S1 of this voltage waveform is made in phase with the voltage waveform of the output signal Vo of the detection circuit 6 by the phase shift circuit 4. Therefore, the time t = t ₁ is a whole so as to correspond to the time t = t ₂ becomes the signal S2 of the phase voltage waveform. This phase shift circuit 4
May be inserted after the oscillation circuit 3 instead of the oscillation circuit 3 to shift the phase of the detection signal Vo.

Upon receiving the clockwise angular velocity, the detection circuit 6 detects the detection signal Vo having a voltage waveform of a peak voltage proportional to the angular velocity.
Occurs. The detection signal Vo is inverted by 180 degrees by the inverting circuit 7, and the inverted signal V1 having the same peak voltage waveform is obtained.
Becomes

The voltage waveform of the output signal S2 of the phase shift circuit 4 is
The waveform shaping circuit 5 generates pulse signals S3 and S4 having voltage waveforms that are 180 degrees out of phase. This pulse signal S3
The S4, the transmission gate 38 of the detection circuit 8, the pulse signal S3 is when the high level "H", for example, conducts between t ₈ from the time t ₂ from between and time t ₆ of t _4. Therefore, only the plus portion of the detection signal Vo is the output of the transmission gate 38.

The transmission circuit of the detection circuit 8
When the gate 39 is a pulse signal S4 high level "H", for example, from between and times t ₄ from the time t ₁ t ₂ t ₆
Conducts during the period. Therefore, only the plus portion of the inverted signal V1 is the output of the transmission gate 39.
Therefore, the detection circuit 8 combines the two detection waveforms to obtain a detection output signal V2 having a voltage waveform having a continuous positive portion. The detection output signal V2 has its AC component cut by the low-pass filter 9, and becomes a positive DC output voltage V3 proportional to the angular velocity.

Next, when the tuning fork vibrator 1 receives an angular velocity of left rotation in the Y-axis direction, the signal of each part in FIG. 1 has a waveform as shown in FIG. Oscillator circuit 3 output signal S1
The waveforms of the output signal S2 of the phase shift circuit 4 and the pulse signals S3 and S4 output from the waveform shaping circuit 5 are the same as those at the time of clockwise rotation.

When the left rotation angular velocity is received, the detection signal Vo by the detection circuit 6 has a peak value proportional to the angular velocity, and has a voltage waveform having a phase opposite to that when the right rotation angular velocity is received. This detection signal Vo is inverted by 180 degrees in the inverting circuit 7 to become an inverted signal V1 having the same peak value. The inverted signal V1 also has a voltage waveform that is in the opposite phase to that when receiving the clockwise angular velocity.

The pulse signals S3 and S from the waveform shaping circuit 5
4, the pulse signal S as described for the clockwise rotation
3 when the high level "H", for example, between from the time t ₂ of t ₄ and time t ₆ of t _8, the transmission gate 38 of the detection circuit 8 becomes conductive. Therefore, only the minus part of the detection signal Vo is output.

The pulse signal S4 is at a high level "H".
At this time, for example, the transmission gate 39 of the detection circuit 8 is turned on between the times t ₁ and t ₂ and between the times t ₄ and t ₆ . Therefore, only the minus part of the inverted signal V1 is output. From this detection circuit 8, the above 2
The two outputs are combined to obtain a detection output signal V2 having a voltage waveform in which the minus portion is continuous. The detection output signal V2
However, the AC component is cut off by the low-pass filter 9, and becomes a negative DC output voltage V3 proportional to the angular velocity.

As described above, when receiving the clockwise angular velocity, a positive DC output voltage proportional to the angular velocity is applied, and when receiving the clockwise angular velocity, a negative DC output voltage proportional to the angular velocity is applied. Can be obtained.

[Modification of First Embodiment] FIG. 9 shows a modification of the detection circuit 6 in the first embodiment. This detection circuit includes a first resistor 81 (resistance R) between the output terminal of the operational amplifier 33 and the ground line 57.
a) and a series circuit of a second resistor 82 (resistance value Rb) are connected, and the minus input terminal and the output terminal of the operational amplifier 33 are connected via the feedback resistor 34 and the first resistor 81. . That is, one end of the feedback resistor 34 is connected to the minus input terminal of the operational amplifier 33, and the other end is connected to a connection point between the first resistor 81 and the second resistor 82.

In this case, the output voltage of the operational amplifier 33, that is, the detection signal Vo is as follows: Vo = −Is · Rf (1 + Ra / Rb) where Rf is the resistance value of the feedback resistor 34 and Is is the feedback current value. Even if the feedback resistor 34 having a low resistance value Rf is used, the output voltage can be adjusted with the resistance ratio Ra / Rb. Also,
For the feedback resistor 34, a metal film resistor or the like having good temperature characteristics is used as a resistor having a low resistance value, and the first resistor 81 and the second resistor 8 are used.
If a resistor having the same temperature characteristic as that of No. 2 is used, a detection circuit having very good temperature characteristics can be realized.

FIGS. 10 and 11 are views similar to FIGS. 3 and 4 showing a modified example of the tuning fork vibrator 1. This tuning fork resonator 1 is also a crystal resonator, and the driving arm 101, the detection arm 102, and the base 103 are integrally formed by a quartz plate in the same manner as the tuning fork resonator shown in FIGS. It is.

This tuning fork vibrator 1 is different from the tuning fork vibrator shown in FIGS. 3 and 4 in that, of the driving electrodes formed on the surface of the driving arm 101, one of the driving electrodes 13 and 14 is used instead of the driving electrodes 13 and 14. The detection electrodes 76, 77 and 78, 79 are formed only on two points parallel to the Z direction as the detection electrodes of the detection arm 102 and the point where the two drive electrodes 19 are formed. The only difference is that the connecting electrodes 77 and 79 are connected at the connecting portion L9, and the second detecting electrodes 76 and 78 are connected at the connecting portion L8. Even if this tuning fork vibrator 1 is used, the angular velocity detecting device shown in FIG. 1 can be configured, and the same operation and effect as those described above can be obtained.

In the embodiment described above, the in-plane vibration in the X direction of the tuning fork vibrator (crystal vibrator) 1 is used as the resonance frequency. However, the detection arm 102 is used for driving, and the driving arm 101 is used for detection. By doing so, the out-of-plane vibration in the Z direction can be set to the resonance frequency. The same can be achieved by using an X-cut vibrator rotated by 90 degrees about the Y axis of the crystal as a tuning fork vibrator.

Although the material of the piezoelectric single crystal forming the tuning fork vibrator 1 has been described as an example of quartz, a 130 ° Y-plate lithium tantalate single crystal, lithium niobate single crystal, lithium borate single crystal, etc. Other single crystal materials exhibiting the above piezoelectric properties may be used.

[Second Embodiment: FIGS. 12 to 14] Next, a second embodiment of the angular velocity detecting device according to the present invention will be described with reference to FIGS. FIG. 12 is a circuit diagram showing the entire configuration of the angular velocity detecting device.
Except for the detection circuit 6 ', the tuning fork vibrator 1 and each of the circuits 3 to
5, 7 to 9 are the same as those of the angular velocity detecting device of the first embodiment shown in FIG.

Detection circuit 6 'in this angular velocity detection device
Connects the positive input terminal of the operational amplifier 33 to the ground wire 57 via a parallel circuit of the resistor 45 and the capacitor 46, and connects the second detection electrodes 16 and 17 of the detection arm of the tuning fork vibrator 1.
And the negative input terminal of the operational amplifier 33, and the negative input terminal and the output terminal of the operational amplifier 33 are connected via a feedback resistor.

The operation of the detection circuit 6 'will be described with reference to an equivalent circuit diagram shown in FIG. In the detection circuit 6 ′, the resistance 45 (resistance value Ri) and the capacitance 46 (capacitance value Ci) connected in parallel between the plus input terminal of the operational amplifier 33 and the ground line 57 indicate the temperature of the operational amplifier 33. To compensate for the change in input bias current. If this resistance 45
Without this, if the input bias current of the minus input terminal of the operational amplifier 33 increases by ΔIb ₁ , the output voltage Vo = −
(Is + △ Ib ₁ ) Rf, and fluctuates by − △ Ib ₁ · Rf.

The input bias current of the plus input terminal is ΔI
Assuming that b ₂ changes, the voltage at the plus input terminal is △ Ib ₂
Ri increases. Therefore, △ Ib ₁ · Rf = △ Ib ₂
If the resistance value Ri of the resistor 45 is selected so as to be Ri, the output voltage of the operational amplifier 33 is Is · Rf,
Fluctuations can be suppressed. Most of the noise components can be removed by bypassing the capacitor 46. Generally, the input bias currents {Ib ₁ and {
The operational amplifier 33 can be configured so that Ib ₂ is equal. Therefore, the resistance Ri of the resistor 45 may be set to a value equal to the resistance Rf of the feedback resistor 34.

FIG. 14 shows a modification of the detection circuit 6 '. Similar to the modification of the first embodiment shown in FIG. 9, the detection circuit 6' is connected between the output terminal of the operational amplifier 33 and the ground line 57. First
The resistance 81 (resistance value Ra) and the second resistance 82 (resistance value R
b), and the minus input terminal and the output terminal of the operational amplifier 33 are connected via a feedback resistor and a first resistor 81. That is, one end of the feedback resistor 34 is connected to the minus input terminal of the operational amplifier 33, and the other end is connected to a connection point between the first resistor 81 and the second resistor 82.

In this case, the output voltage of the operational amplifier 33, that is, the detection signal Vo also becomes Vo = −Is · Rf (1 + Ra / Rb), where Rf is the resistance value of the feedback resistor 34 and Is is the feedback current value. Therefore, the feedback resistor 3 having a relatively low resistance value Rf
4, the output voltage can be adjusted by the resistance ratio Ra / Rb. Further, if a metal film resistor or the like having good temperature characteristics is used for the feedback resistor 34 as a resistor having a low resistance value, and the first resistor 81 and the second resistor 82 have the same temperature characteristics, the temperature characteristics will be very low. A good detection circuit can be realized. The first detection electrode 15 of the detection arm 102 of the tuning fork vibrator 1
It is the same as in the first embodiment that the equivalent resistance or the equivalent electrical impedance between 18 and the second detection electrodes 16 and 17 is desirably 10 kΩ or more.

The driving arm 101 of the tuning fork vibrator 1
The resonance frequency of the self-excited vibration of f0 (Hz)
02, the resonance frequency f0 (Hz) of the driving arm 101 and the resonance frequency of the detection arm 102 when the resonance frequency of the vibration in the direction orthogonal to the vibration direction of the self-excited vibration of the driving arm 101 is f1 (Hz). The value of the detuning frequency Δf = f0−f1 between f1 (Hz) and f1 / 1000 to f1 / 10, or −f1 / 1000 to −f1 /
Desirably between 10 and 10 is the same as in the first embodiment.

[Third Embodiment: FIGS. 15 to 17] Next, a third embodiment of the angular velocity detecting device according to the present invention will be described with reference to FIGS. FIG. 15 is a circuit diagram showing the entire configuration of the angular velocity detecting device.
Except for the detection circuit 6 ″, the tuning fork vibrator 1 and each of the circuits 3 to
5, 7 to 9 are the same as those of the angular velocity detecting device of the first embodiment shown in FIG.

A detection circuit 6 ″ in this angular velocity detecting device
Connects the plus input terminal of the operational amplifier 33 to the ground line 57 via the resistor 45, and connects the second detection electrodes 16 and 17 formed on the detection arm 102 of the tuning fork vibrator 1 to the minus input of the operational amplifier 33. The negative input terminal and the output terminal of the operational amplifier 33 are connected via a feedback resistor. Further, the output terminal and the plus input terminal of the operational amplifier 33 are connected via an integrating circuit.
The integration circuit is composed of an operational amplifier 47, a resistor 48 and a capacitor 49.

The operational amplifier 47 constituting this integrating circuit
Has a positive input terminal connected to the ground line 57, a negative input terminal connected to the output terminal of the operational amplifier 33 via a resistor 48, and a capacitor 49 connected between the negative input terminal and the output terminal. The operation of the detection circuit 6 "is shown in FIG.
This will be described with reference to an equivalent circuit diagram shown in FIG.

In the detection circuit 6 ″, the operational amplifier 3
3 between the output terminal and the plus input terminal of the detection circuit 6 "compensates for the offset drift fluctuation of the output voltage (detection signal) Vo of the detection circuit 6". By inverting the voltage and feeding it back to the plus input terminal of the operational amplifier 33, the DC output component is controlled to be zero.

At this time, if the resistance value of the resistor 48 is R2 and the capacitance 45 is C2, the cutoff frequency fc is fc = fc
1 / 2πR2 · C2. This fc is the resonance frequency f0
The resistance value R2 of the resistor 48 and the capacitance 4
9 is set as the capacitance value C2. Cutoff frequency fc
Since the output of the integrating circuit of the above AC frequency is attenuated and becomes 0, there is no influence of the integrating circuit at the resonance frequency f0, and the output voltage Vo of the detection circuit 6 ″ becomes −Rf · Is.

FIG. 17 shows a modification of the detection circuit 6 ". Similar to the modification of the first embodiment shown in FIG. 9, between the output terminal of the operational amplifier 33 and the ground line 57. , A series circuit of a first resistor 81 (resistance value Ra) and a second resistor 82 (resistance value Rb) is connected, and a minus input terminal and an output terminal of the operational amplifier 33 are connected to a feedback resistor and the first resistor 81. That is, one end of the feedback resistor 34 is connected to the minus input terminal of the operational amplifier 33, and the other end is connected to a connection point between the first resistor 81 and the second resistor 82. .

In this case, the output voltage of the operational amplifier 33, that is, the detection signal Vo also becomes Vo = −Is · Rf (1 + Ra / Rb), where Rf is the resistance value of the feedback resistor 34 and Is is the feedback current value. Therefore, the feedback resistor 3 having a relatively low resistance value Rf
4, the output voltage can be adjusted by the resistance ratio Ra / Rb. Further, if a metal film resistor or the like having good temperature characteristics is used for the feedback resistor 34 as a resistor having a low resistance value, and the first resistor 81 and the second resistor 82 have the same temperature characteristics, the temperature characteristics will be very low. A good detection circuit can be realized.

Note that the detection arm 102 of the tuning fork vibrator 1
The first detection electrodes 15 and 18 and the second detection electrode 1
Desirably, the equivalent resistance or equivalent electrical impedance between the first and the second and the sixth and the 17th have a value of 10 kΩ or more.
This is the same as in the first embodiment.

The driving arm 101 of the tuning fork vibrator 1
The resonance frequency of the self-excited vibration of f0 (Hz)
02, the resonance frequency f0 (Hz) of the driving arm 101 and the resonance frequency of the detection arm 102 when the resonance frequency of the vibration in the direction orthogonal to the vibration direction of the self-excited vibration of the driving arm 101 is f1 (Hz). The value of the detuning frequency Δf = f0−f1 between f1 (Hz) and f1 / 1000 to f1 / 10, or −f1 / 1000 to −f1 /
Desirably between 10 and 10 is the same as in the first embodiment.

[Fourth Embodiment: FIGS. 18 to 20] In each of the above embodiments, an example in which a tuning fork vibrator is used as a vibrator has been described. However, the present invention is not limited to this, and at least one drive A vibrator having at least one detection arm and at least one detection arm may be used. Therefore, an embodiment of an angular velocity detecting device using a three-forked vibrator as a vibrator will be described below.

FIGS. 18 and 19 are a perspective view seen from the front side and a perspective view seen from the back side of the three-pronged vibrator.
The three-pronged vibrator 2 is also a quartz oscillator, and is formed from a quartz plate, which is a piezoelectric single crystal body, by mechanical processing using a wire saw or chemical processing such as etching.

The three-forked vibrator 2 has three arms including two drive arms 110 and 112 and one detection arm 111, and the three arms 110 and 11.
2 and 111 are provided in parallel with each other. The two drive arms 110 and 112 are arranged at both ends in the X direction shown in FIG. 18, and the detection arm 111 is arranged in the middle thereof, and both extend in the Y direction. The base 100 is supported by a support member (not shown).

In FIG. 18, the X direction is substantially parallel to the electric axis of the quartz crystal, the Y direction is substantially parallel to the mechanical axis of the quartz crystal, and the Z direction is substantially parallel to the optical axis of the quartz crystal. It may be rotated about 10 degrees. Although FIGS. 18 and 19 show examples of the Z-cut vibrator in which the crystal is cut in the optical axis direction, that is, the Z direction, an X-cut vibrator in which the electric axis direction is cut may be used.

The driving arms 110 and 112 have a prismatic shape, and have driving electrodes 113, 114, 115 and 116 on the respective side surfaces of the driving arm 110. Driving electrode 121,
122, 123, and 124. These driving arms 110 and 112 are arms that self-excitedly vibrate at a resonance frequency in the X direction (in-plane direction).

The detection arm 111 also has a prismatic shape, and has first detection electrodes 118 and 119 and second detection electrodes 117 and 120 on two opposing side surfaces. An arm that vibrates in the same X direction as the driving arm in synchronization with it, and forcibly vibrates in the Z direction orthogonal to the direction of self-excited vibration at the same frequency as the resonance frequency of the driving arm due to Coriolis force due to rotation. is there. These drive electrodes 113 to 116 and 121 to 124 and the detection electrodes 117 to 120 are formed by a metal film forming method such as vacuum evaporation or sputtering.

The driving electrodes 113 and 114 formed on the opposing surface of the driving arm 110 are
It is connected above and is connected to the terminal T11 provided at the lower end of the base 110 by the drawer L11. Similarly, the driving electrodes 115 and 116 formed on the other facing surface of the driving arm 110 are also connected on the driving arm 110 and are connected to the terminal T12 by the lead-out portion L12.

The driving electrodes 121 and 122 formed on the opposite surface of the driving arm 112
It is connected above and is connected to a terminal T15 provided at the lower end of the base 100 by a drawer L15. Similarly, the driving electrodes 123 and 124 formed on the other facing surface of the driving arm 112 are also connected on the driving arm 112 and are connected to the terminal T16 by the lead portion L16.

The first detection electrodes 118 and 119 formed on the opposite surface of the detection arm 111 are connected on the detection arm 111, and are connected to the base 10 by a lead-out portion L13.
0 is connected to a terminal T13 provided at the lower end.
Similarly, the detection electrodes 117 and 120 formed on the same opposing surface of the detection arm 111 are also connected on the detection arm 111, and are connected to the terminal T14 by the lead L14.

As specific examples of the dimensions of the three-forked vibrator 2, drive arms 110 and 11 that vibrate in a plane (X direction) are provided.
2 and each width of the detection arm 111 is 600 μm.
m and length are all 3700 μm, the total length of the three-forked vibrator 2 is 5900 μm, the overall width is 2200 μm, and the resonance frequency f1 (Hz) of out-of-plane (Z direction) vibration is changed to the resonance frequency f0 (Hz) of in-plane vibration Thickness is 60 to get closer
0 μm.

FIG. 20 is a circuit diagram showing the overall structure of the fourth embodiment of the angular velocity detecting device according to the present invention. The above-described three-forked vibrator 2 replaces the tuning fork vibrator 1 in FIG.
Except for using, the description is omitted because it is the same as the first embodiment described with reference to FIG.

The three-forked vibrator 2 includes two drive arms 11
Driving electrodes 113, 114 and 1 provided on 0 and 112
21 and 122 are put together, and the oscillation circuit 3
Connected to the output terminal of the operational amplifier 20
5, 116 and 123, 124 are connected together to the minus input terminal of the operational amplifier 19 of the oscillation circuit 3 by the conducting wire 50.

Further, the first detection electrodes 118 and 119 provided on the detection arm 111 are connected to the ground line 57, and the detection electrodes 117 and 120 are connected to the negative terminal of the operational amplifier 33 of the detection circuit 6 by the conducting wire 56. Connected to input terminal. The first embodiment is different from the first embodiment in that the positive input terminal of the operational amplifier 33 is connected to the ground line 57, and the negative input terminal and the output terminal are connected via the feedback resistor 34 to constitute the detection circuit 6. Is the same as

This angular velocity detector also operates in the same manner as in the first embodiment, and has a polarity and a magnitude corresponding to the direction of the angular velocity due to the rotation received by the three-forked oscillator 2 from the output terminal of the low-pass filter 9. Is obtained as the absolute value of the DC voltage.

Further, the detection circuit 6 is changed as shown in FIG. 9 (however, the trike oscillator 2 is connected instead of the tuning fork oscillator 1), and the output terminal of the operational amplifier 33 and the ground line 57 are connected.
, A series circuit of a first resistor 81 (resistance value Ra) and a second resistor 82 (resistance value Rb) is connected, and the negative input terminal and output terminal of the operational amplifier 33 are connected to the feedback resistor 34 and The connection may be made via the resistor 81. Thereby, a detection circuit having good temperature characteristics can be realized.

The drive arm 1 of the three-forked vibrator 2
By using the detection arms 10 and 112 as detection arms and the detection arm 111 as drive arms, the out-of-plane vibration in the Z direction in FIG. 18 can be made the resonance frequency. The same can be applied to a case where the three-forked vibrator 2 is an X-cut vibrator rotated by 90 degrees around the Y axis of quartz.

Although the example of the material of the piezoelectric single crystal forming the three-forked vibrator 2 is quartz crystal, a 130 ° Y-plate lithium tantalate single crystal, lithium niobate single crystal, lithium borate single crystal, etc. Other single crystal materials exhibiting the above piezoelectric properties may be used. Further, the detection arm 11 of the three-forked oscillator 2
It is desirable that the equivalent resistance or equivalent electrical impedance between one first detection electrode 118, 119 and the second detection electrode 117, 120 is 10 kΩ or more.

Then, the driving arm 11 of the three-forked vibrator 2
When the resonance frequency of the self-excited vibrations 0 and 112 is f0 (Hz), and the resonance frequency of the detection arm 111 in the direction orthogonal to the vibration direction of the self-excited vibration of the driving arm is f1 (Hz), The value of the detuning frequency Δf = f0−f1 between the resonance frequency f0 (Hz) of the detection arm and the resonance frequency f1 (Hz) of the detection arm is changed from f1 / 1000 to f1 / 1.
Desirably, it is between 0 and between -f1 / 1000 and -f1 / 10, as in the first to third embodiments. The same applies to the following fifth and sixth embodiments.

[Fifth Embodiment: FIG. 21] Next, a fifth embodiment of the angular velocity detecting device according to the present invention will be described.
FIG. 21 is a circuit diagram showing the entire configuration of the angular velocity detecting device. This is different from the angular velocity detecting device of the above-described fourth embodiment shown in FIG. 20 only in the detection circuit 6 ', and is different from the angular velocity detecting device of the fourth embodiment shown in FIG. The only difference is that a three-pronged vibrator 2 similar to that of the above-described fourth embodiment is used in place of 1 and the operation of the detection circuit 6 'is the same as that described with reference to FIG. I do.

In the angular velocity detecting device according to the fifth embodiment, the three-forked vibrator 2 is used as the vibrator, and the positive input terminal of the operational amplifier 33 is connected to the resistor 45 and the capacitor 46 in the detecting circuit 6 '. This is characterized in that it is connected to the ground line 57 via the parallel circuit of. Also in this case, the detection circuit 6 'can be changed to a circuit as shown in FIG. The function and effect thereby are the same as those described with reference to FIG.

[Sixth Embodiment: FIG. 22] Next, a sixth embodiment of the angular velocity detecting device according to the present invention will be described.
FIG. 22 is a circuit diagram showing the entire configuration of the angular velocity detecting device. This is different from the angular velocity detection device of the fourth embodiment shown in FIG. 20 only in the detection circuit 6 ″, and is different from the angular velocity detection device of the fourth embodiment shown in FIG. The only difference is that a three-pronged vibrator 2 similar to that of the above-described fourth embodiment is used in place of 1 and the operation of the detection circuit 6 ″ is the same as that described with reference to FIG. I do.

In the angular velocity detecting device according to the sixth embodiment, the three-forked vibrator 2 is used as a vibrator, and the positive input terminal of the operational amplifier 33 is grounded via the resistor 45 in the detecting circuit 6 ″. Line 57 and connect the positive input terminal and the output terminal of the operational amplifier 33 to the operational amplifier 47.
It is characterized in that it is connected via an integrating circuit composed of a resistor 48 and a capacitor 49. Also in this case, the detection circuit 6 "can be changed to a circuit as shown in Fig. 17. The operation and effect obtained thereby are the same as those described with reference to Fig. 17.

[Modified Example of Trifurcated Vibrator: FIGS. 23 to 2
5] FIGS. 23 to 25 show various modifications of the three-pronged vibrator used in the above-described fourth to sixth embodiments. These figures are top views showing only the drive arm and the detection arm of the three-forked vibrator, and the arrangement of the drive electrode and the detection electrode formed on them, and the base is not shown. .

The three-forked vibrator shown in FIG. 23 is provided with two detecting arms 111 and 125 and one driving arm 112 between them. The driving electrodes provided on the opposing surfaces of the driving arm 112 are connected to the terminals T10 and T20, respectively, which are connected to each other. The first detection electrode and the second detection electrode of the detection arms 111 and 125 are connected in parallel, and are led to terminals T30 and T40, respectively. As described above, by using two detection arms, the translational acceleration can be canceled.

In the three-forked vibrator shown in FIG. 24, one of the detecting arms 125 in the three-forked vibrator shown in FIG. 23 is replaced with a driving arm 110, and the driving arm and the detecting arm are separated. This facilitates the formation of electrodes by vacuum deposition or sputtering.

In the three-forked vibrator shown in FIG. 25, one arm of the three arms is a driving arm 110, the other arm is a detection arm 111, and an intermediate arm 1
26 has no electrode provided. As described above, by separating the drive arm 110 and the detection arm 111, electrical coupling can be prevented and detection accuracy can be increased.

In each of the embodiments described above, an example was described in which the material of the substrate of the vibrator was quartz. However, a single crystal of lithium tantalate, a single crystal of lithium niobate, and a single crystal of lithium borate of a 130 ° Y plate were used. A single crystal material having piezoelectricity such as a crystal may be used.

[0127]

As described above, the angular velocity detecting device according to the present invention can detect the angular velocity by using the vibrator made of a single crystal having piezoelectricity. The drive electrode can be formed on the drive arm of the child and the detection electrode can be formed on the detection arm by direct vacuum evaporation or sputtering, respectively, and the shape is simplified. Further, since it is not necessary to bond the piezoelectric element to the vibrator, the assembly process is simplified, the overall shape can be reduced, and the cost can be reduced. Furthermore, since the piezoelectric single crystal is used for the vibrator, the temperature characteristics are remarkably improved, and the deterioration of the characteristics due to aging can be prevented.

Further, the first detection electrode of the detection arm of the tuning fork vibrator or the three-fork vibrator and the positive input terminal of the operational amplifier constituting the detection circuit are connected to the same potential earth line,
Using a detection circuit in which the second detection electrode is connected to the minus input terminal of the operational amplifier, and the minus input terminal and the output terminal of the operational amplifier are connected via a feedback resistor, two equivalent detection circuits are used. Short-circuit the feedback electrode R
Since a short-circuit current flows through f and the short-circuit current is directly converted into a voltage, a sufficient detection output can be obtained without being affected by noise voltage even when the equivalent electric impedance between the two detection electrodes is 10 kΩ or more. Can be.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an overall configuration of a first embodiment of an angular velocity detecting device according to the present invention.

FIG. 2 is a circuit diagram for explaining an equivalent circuit of the tuning fork vibrator and an operation principle of a detection circuit.

FIG. 3 is a perspective view showing an example of the appearance of the tuning fork vibrator as viewed obliquely from the right front side.

FIG. 4 is a perspective view of the tuning fork vibrator viewed from an obliquely right back side.

FIG. 5 is a diagram illustrating a reactance characteristic with respect to a frequency of a detection arm of the tuning fork vibrator according to the first embodiment of the present invention.

FIG. 6 is a diagram showing frequency versus gain characteristics when the input impedance of the detection circuit shown in FIG. 1 is changed.

FIG. 7 is a waveform diagram of each signal in FIG. 1 when the tuning fork vibrator of the angular velocity detecting device according to the present invention receives a clockwise angular velocity.

FIG. 8 is a waveform diagram of each signal when receiving a left-rotating angular velocity.

FIG. 9 shows a detection circuit 6 according to the first embodiment of the present invention.
FIG. 9 is a circuit diagram showing a modification example of FIG.

FIG. 10 is a perspective view similar to FIG. 3, showing a modification of the tuning fork vibrator.

FIG. 11 is a perspective view similar to FIG. 4;

FIG. 12 is a circuit diagram showing the overall configuration of a second embodiment of the angular velocity detecting device according to the present invention.

FIG. 13 is a circuit diagram for explaining an equivalent circuit of the tuning fork vibrator and an operation principle of the detection circuit.

FIG. 14 is a circuit diagram showing a modified example of the detection circuit 6 'according to the second embodiment of the present invention.

FIG. 15 is a circuit diagram showing an overall configuration of a third embodiment of the angular velocity detecting device according to the present invention.

FIG. 16 is a circuit diagram for explaining the equivalent circuit of the tuning fork vibrator and the operation principle of the detection circuit.

FIG. 17 is a circuit diagram showing a modified example of the detection circuit 6 ″ according to the third embodiment of the present invention.

FIG. 18 is a perspective view, viewed from the right front side, showing an example of the appearance of a three-pronged vibrator used in the fourth to sixth embodiments of the angular velocity detecting device according to the present invention.

FIG. 19 is a perspective view of the same seen from the back right side.

FIG. 20 is a circuit diagram showing the overall configuration of a fourth embodiment of the angular velocity detecting device according to the present invention.

FIG. 21 is a circuit diagram showing an overall configuration of a fifth embodiment of the angular velocity detecting device according to the present invention.

FIG. 22 is a circuit diagram showing an overall configuration of a sixth embodiment of the angular velocity detecting device according to the present invention.

FIG. 23 is a top view showing only a drive arm and a detection arm, and only the arrangement of the drive electrode and the detection electrode in a modified example of the three-pronged vibrator used in the present invention.

FIG. 24 is a top view similar to FIG. 23, showing another modification.

FIG. 25 is a top view similar to FIG. 23, showing still another modification.

FIG. 26 is a circuit diagram for explaining an operation of a detection circuit in a conventional angular velocity detection device.

FIG. 27 is a diagram showing theoretical limits of voltage measurement by a conventional detection circuit.

[Explanation of symbols]

 1: Tuning fork vibrator 2: Three-forked vibrator 3: Oscillation circuit 4: Phase shift circuit 5: Waveform shaping circuit 6, 6 ', 6 ": Detection circuit 7: Inverting circuit 8: Detection circuit 9: Low-pass filter 10 to 14: Driving electrodes 15 to 18: Detection electrodes 33: Operational amplifier 34: Feedback resistors 45, 48: Resistors 46, 49: Capacitance 57: Ground wire 81: First resistor 82: Second resistor 100, 103: Base 101 , 110, 112: drive arm 102, 111, 125: detection arm 113-116, 121-124: drive electrode 117-120: detection electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. Hei 11-1564 (32) Priority date January 7, 1999 (Jan. 1999) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 11-21536 (32) Priority date January 29, 1999 (Jan. 29, 1999) (33) Priority claim country Japan (JP)

Claims (9)

[Claims] A plurality of drive electrodes, a drive arm that self-oscillates at a resonance frequency in a predetermined direction (X or Z direction), and first and second detection electrodes; Vibrates in the same direction (X or Z direction) as the drive arm in synchronization with the drive arm, and forcibly vibrates at the same frequency as the resonance frequency of the drive arm by the Coriolis force accompanying rotation. A tuning fork vibrator made of a piezoelectric single crystal having a detection arm vibrating in a direction (Z or X direction) orthogonal to the above, and a drive arm and a base provided with the detection arm in parallel with each other; An oscillation circuit connected to each drive electrode of the arm for self-exciting the drive arm; and an operational amplifier for detecting vibration of the detection arm due to Coriolis force caused by rotation of the tuning fork vibrator. Detection circuit and A first detection electrode of the detection arm is connected to a ground line, and the detection circuit is connected to a positive input terminal of the operational amplifier to the ground line, and a second detection of the detection arm is performed. Electrode and the negative input terminal of the operational amplifier,
Further, an angular velocity detecting device, wherein a minus input terminal and an output terminal of the operational amplifier are connected via a feedback resistor. 2. A driving arm comprising: a plurality of driving electrodes; a driving arm which self-oscillates at a resonance frequency in a predetermined direction (X or Z direction); and first and second detection electrodes. Vibrates in the same direction (X or Z direction) as the drive arm in synchronization with the drive arm, and forcibly vibrates at the same frequency as the resonance frequency of the drive arm by the Coriolis force accompanying rotation. A tuning fork vibrator made of a piezoelectric single crystal having a detection arm vibrating in a direction (Z or X direction) orthogonal to the above, and a drive arm and a base provided with the detection arm in parallel with each other; An oscillation circuit connected to each drive electrode of the arm for self-exciting the drive arm; and an operational amplifier for detecting vibration of the detection arm due to Coriolis force caused by rotation of the tuning fork vibrator. Detection circuit and Connecting a first detection electrode of the detection arm to a ground line, and connecting the detection circuit to the ground line via a parallel circuit of a resistor and a capacitor at a positive input terminal of the operational amplifier. ,
An angular velocity, wherein a second detection electrode of the detection arm is connected to a minus input terminal of the operational amplifier, and a minus input terminal and an output terminal of the operational amplifier are connected via a feedback resistor. Detection device. 3. A driving arm, comprising: a plurality of driving electrodes; a driving arm that self-oscillates at a resonance frequency in a predetermined direction (X or Z direction); and first and second detection electrodes. Vibrates in the same direction (Z or Y direction) as the drive arm in synchronization with the drive arm, and forcibly vibrates at the same frequency as the resonance frequency of the drive arm by the Coriolis force caused by rotation. A tuning fork vibrator made of a piezoelectric single crystal having a detection arm vibrating in a direction (Z or X direction) orthogonal to the above, and a drive arm and a base provided with the detection arm in parallel with each other; An oscillation circuit connected to each drive electrode of the arm for self-exciting the drive arm; and an operational amplifier for detecting vibration of the detection arm due to Coriolis force caused by rotation of the tuning fork vibrator. Detection circuit and Connecting a first detection electrode of the detection arm to a ground line; connecting the detection circuit to the ground line via a resistor at a positive input terminal of the operational amplifier; A second detection electrode is connected to a minus input terminal of the operational amplifier, a minus input terminal and an output terminal of the operational amplifier are connected via a feedback resistor, and an output terminal and a plus input terminal of the operational amplifier are further connected. Are connected via an integrating circuit. 4. A piezoelectric single crystal having at least one drive arm and at least one detection arm, three arms including: a base having the three arms provided in parallel with each other; The drive arm has a plurality of drive electrodes, and is an arm that self-oscillates at a resonance frequency in a predetermined direction (X or Z direction), and the detection arm has first and second detection electrodes. The drive arm vibrates in the same direction (X or Z direction) as the drive arm in synchronization with the drive arm, and is forced to have the same frequency as the resonance frequency of the drive arm by Coriolis force accompanying rotation. A trifurcated vibrator that is an arm that vibrates in a direction (Z or X direction) orthogonal to the direction of the excitation vibration, and an oscillation circuit that is connected to each drive electrode of the drive arm and causes the drive arm to self-oscillate. And rotation of the three-forked oscillator A detection circuit having an operational amplifier for detecting the vibration of the detection arm due to the accompanying Coriolis force, wherein a first detection electrode of the detection arm is connected to a ground wire, and the detection circuit is A positive input terminal of the operational amplifier is connected to the ground line, a second detection electrode of the detection arm is connected to a negative input terminal of the operational amplifier, and a negative input terminal and an output terminal of the operational amplifier are further connected. Are connected via a feedback resistor. 5. A piezoelectric single crystal having at least one drive arm and at least one detection arm, three arms including: a base having the three arms provided in parallel with each other; The drive arm has a plurality of drive electrodes, is an arm that self-oscillates at a resonance frequency in a predetermined direction (X or Z direction), and the detection arm has first and first detection electrodes. Vibrates in the same direction (X or Z direction) as the drive arm in synchronization with the drive arm, and is forcibly excited at the same frequency as the resonance frequency of the drive arm by the Coriolis force accompanying rotation. A three-forked vibrator, which is an arm that vibrates in a direction (Z or X direction) orthogonal to the direction of vibration, an oscillation circuit that is connected to each drive electrode of the drive arm and that causes the drive arm to self-excited The rotation of the three-forked oscillator A detection circuit having an operational amplifier for detecting vibration of the detection arm due to Coriolis force, wherein a first detection electrode of the detection arm is connected to a ground wire, and the detection circuit is Connect the positive input terminal of the operational amplifier to the ground line via a parallel circuit of a resistor and a capacitor,
The second detection electrode of the detection arm is connected to the minus input terminal of the operational amplifier, and the minus input terminal and the output terminal of the operational amplifier are connected via a feedback resistor. Angular velocity detecting device. 6. A piezoelectric single crystal having at least one drive arm and at least one detection arm, three arms including: a base provided with the three arms in parallel with each other; The drive arm has a plurality of drive electrodes, and is an arm that self-oscillates at a resonance frequency in a predetermined direction (X or Z direction), and the detection arm has first and second detection electrodes. The drive arm vibrates in the same direction (X or Z direction) as the drive arm in synchronization with the drive arm, and is forced to have the same frequency as the resonance frequency of the drive arm by Coriolis force accompanying rotation. A trifurcated vibrator that is an arm that vibrates in a direction (Z or X direction) orthogonal to the direction of the excitation vibration, and an oscillation circuit that is connected to each drive electrode of the drive arm and causes the drive arm to self-oscillate. And rotation of the three-forked oscillator A detection circuit having an operational amplifier for detecting the vibration of the detection arm due to the accompanying Coriolis force, wherein a first detection electrode of the detection arm is connected to a ground wire, and the detection circuit is A positive input terminal of the operational amplifier is connected to the ground line via a resistor, a second detection electrode of the detection arm is connected to a negative input terminal of the operational amplifier, and a negative input terminal of the operational amplifier is connected to the negative input terminal of the operational amplifier. An angular velocity detecting device comprising: an output terminal connected via a feedback resistor; and an output terminal of the operational amplifier and a positive input terminal connected via an integration circuit. 7. The angular velocity detecting device according to claim 1, wherein a first resistor and a second resistor are provided between an output terminal of an operational amplifier constituting the detection circuit and the ground wire. And an output terminal connected to the negative input terminal of the operational amplifier via the feedback resistor and the first resistor. 8. The angular velocity detecting device according to claim 1, wherein said first arm of said detecting arm is provided.
Wherein the equivalent resistance or the equivalent electrical impedance between the detection electrode and the second detection electrode is 10 kΩ or more. 9. The angular velocity detection device according to claim 1, wherein a resonance frequency of self-excited oscillation of the driving arm is f0 (Hz), and the resonance frequency of the driving arm in the detection arm is set to f0 (Hz). When the resonance frequency of the vibration in the direction orthogonal to the vibration direction of the self-excited vibration is f1 (Hz), the resonance frequency between the resonance frequency f0 (Hz) of the driving arm and the resonance frequency f1 (Hz) of the detection arm is obtained. Detuning frequency Δf = f0-f
An angular velocity detecting device, wherein the value of 1 is between f1 / 1000 and f1 / 10 or between -f1 / 1000 and -f1 / 10.