JP2869514B2 - 1-axis angular velocity / acceleration sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-axis angular velocity / acceleration sensor, and more particularly to a one-axis angular velocity / acceleration sensor equipped with a bending type tuning fork type quartz resonator, which is compact, lightweight, inexpensive, has a long life and high reliability. Related to sensors.

[0002]

2. Description of the Related Art A conventional example of a one-axis angular velocity / acceleration sensor will be described with reference to FIGS. FIG. 1 shows a rotating beam type one-axis angular velocity / acceleration sensor. Bearings 12 and 13 are fixed to both end plates 11a and 11b of the cylindrical case 11, and a rotating shaft 21 supported by these bearings is provided.
Is fixed to the piezoelectric beam rotating body 20. The piezoelectric beam rotator 20 includes two beam-shaped piezoelectric detectors 22a and 22a.
2b, which are perpendicular to the rotating shaft 21 and symmetrically fixed to the rotating shaft 21 via the support plate 24. The piezoelectric detectors 22a and 22b can be, for example, those in which electrodes 25a and 25b are formed on both surfaces of a bimorph piezoelectric crystal beam. The free ends of the piezoelectric detectors 22a and 22b are provided with weights 23a and 23b for improving the angular velocity detection sensitivity. Reference numeral 14 denotes a stator of the spin motor, and 15 denotes its rotor. The rotor 15 rotates the rotating shaft 21 at high speed. The detection output detected by the electrodes 25a and 25b of the piezoelectric detectors 22a and 22b reaches the slip rings 24a, 24b and 24c via the wiring in the rotating shaft 21, from which the brushes 16a, 16b and 16c, the preamplifier 31a And 31b to the signal processing circuit.

Referring to FIG. 2A, the X axis is an axis lying on the same plane as the piezoelectric detectors 22a and 22b, and the Z axis is an axis orthogonal to the X axis and coaxial with the rotation axis 21. is there. When the case 11 of the angular velocity / acceleration sensor is rotated at an angular velocity Ωx about the X axis, Coriolis force acts on the piezoelectric detectors 22a and 22b rotating at a high speed at an angular velocity Ωz about the Z axis. 22a and 22b bend in opposite phases as indicated by the dashed line in FIG. 2 (a). As a result, the piezoelectric detectors 22a and 22b
Thus, as shown in FIG. 2B, sine wave voltage signals Xa and Xb having the same amplitude and the same phase of 180 ° are obtained.
Here, if the difference between the output voltage signals of the piezoelectric detectors 22a and 22b is calculated, an X-axis rotation angular velocity component X = Xa-Xb is obtained.

When a vibration acceleration α in the Z-axis direction is applied to the piezoelectric detectors 22a and 22b, the piezoelectric detectors 22a and 22b
2b bends in phase as indicated by the dashed line in FIG. 2 (c). As a result, the piezoelectric detectors 22a and 22b
Thus, as shown in FIG. 2D, sinusoidal voltage signals Za and Zb having the same amplitude and the same phase are obtained. Here, by taking the sum of the output voltage signals of the piezoelectric detectors 22a and 22b, the Z-axis direction acceleration component Z = Za + Zb is obtained.

[0005]

The one-axis angular velocity / acceleration sensor shown in FIG. 1 uses piezoelectric detectors 22a and 22b as a material for detecting angular velocity / acceleration. In many cases, the structure is complicated, and the life of the bearings 12 and 13 of the rotating parts thereof is limited due to wear and abrasion by using a spin motor.

The present invention provides a uniaxial angular velocity / acceleration sensor that does not use a member that wears and wears, but that solves the above-described problem by using a bending-type tuning fork-type crystal resonator. .

[0007]

Means for Solving the Problems Claim 1: Two beams
The quartz thin plate constituting the tuning fork consisting of
Sandwiched between quartz plates, the two beams are uniaxial angular velocity /
A detection electrode for detecting the amount of displacement by speed is
Type tuning fork type water formed on the crystal and two quartz plates on both sides
Variable the capacitance formed by the crystal oscillator
The variable capacitance type displacement detector is used as the capacitance of the position detector.
Oscillation frequency and ratio of two sets of bendable tuning fork crystal units
AC for driving a stabilized displacement detector that is sufficiently high in comparison
Equipped with a voltage oscillator, two sets of variable capacitance displacement detectors
Circuit for determining the difference between the detection signal outputs of
Equipped with a circuit for calculating the sum of the outputs of the capacitance type displacement detector
A one-axis angular velocity / acceleration sensor was constructed.

[0008] Claim 2: Claim 1
In the uniaxial angular velocity / acceleration sensor, the two quartz plates are quartz
Higher rigidity than thin plate, does not interfere with beam vibration
Support a thin quartz plate with a small gap around the beam
1-axis angular velocity with a thin quartz plate sandwiched only in contact with the part
An acceleration sensor was configured.

Further, claim 3: any one of claims 1 and 2
In the one-axis angular velocity / acceleration sensor described in
Vibration component and beam precession caused by application of velocity
Variable displacement component of beam caused by application of acceleration and acceleration
Detected as the AC signal output of the displacement detector,
The signal processing for the angular velocity with respect to the
0 and the output of the two sets of variable capacitance displacement detectors
The difference is obtained and the synchronous detection circuit 130
The synchronous detection is performed by applying the oscillation frequency, and the smoothing circuit 1
At 50, the residual component of the drive AC voltage is smoothed,

The signal processing for acceleration is performed by two sets of variable electrostatic
A differential circuit is used to output the AC signal output of one of the capacitive displacement detectors.
Of the variable capacitance type displacement detector
The other AC signal output of the
The signal is input to the path 121 to obtain the sum, and the driving
One-axis angular velocity / acceleration sensor for smoothing residual components of the stream voltage
Configured.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A bending type tuning-fork type crystal resonator used in a uniaxial angular velocity / acceleration sensor according to the present invention will be described with reference to FIG. FIG. 3A is an exploded perspective view of a bending type tuning fork type crystal resonator. The bent tuning-fork type quartz vibrator is composed of a quartz thin plate 40 and a quartz thin plate 4 forming a tuning fork composed of two beams 42 and 42 ′ vibrating in a bent tuning fork type.
It is composed of two quartz plates 50 and 60 sandwiching 0 from both sides.

The thin quartz plate 40 forms a tuning fork by partially cutting off the two beams 42 and 42 'which are caused to vibrate in a bending-type tuning fork type and the supporting frame 41 thereof. Displacement detecting electrodes are formed on both front and rear surfaces for detecting the amount of displacement caused by uniaxial angular velocity / acceleration applied to both of the two beams 42 and 42 'forming the tuning fork when an angular velocity / acceleration is applied thereto. . That is, a front electrode 43 and a back electrode 33 are formed on both front and back surfaces of the beam 42 as displacement detection electrodes, and a front electrode 43 'and a back electrode 33' are formed on both front and back surfaces of the beam 42 '. Here, two sheets facing each other different from the displacement detection electrodes
Excitation electrodes are formed on two opposite surfaces of a quartz plate or beam
The AC voltage between the excitation electrodes.
Mechanical resonance can be caused.

On the other hand, the two quartz plates 50 and 60 sandwiching the quartz thin plate 40 constituting the tuning fork from both sides thereof are formed in the same shape and structure as shown in FIG. Opposite quartz thin plate 4
This is a quartz plate that constitutes a bending-type tuning-fork-type quartz resonator by sandwiching “0” from both sides thereof. The back electrode 33 formed on the beam 42 of the thin quartz plate 40 is provided on the surface of the quartz plate 50.
And a displacement detection electrode 51 'cooperating therewith is formed, and a displacement detection electrode 51' cooperating with the back electrode 33 'formed on the beam 42' is formed. Similarly, a displacement detection electrode 61 is formed on the back surface of the quartz plate 60 so as to face and cooperate with the front electrode 43 formed on the beam 42 of the thin quartz plate 40, and the beam 4
A displacement detection electrode 61 'is formed opposite to and cooperates with the front electrode 43' formed in 2 '. Quartz sheet 4
The quartz plate 50, the quartz plate 50 and the quartz plate 60 are integrally joined to each other in the order shown in FIG. However, this joining is performed so that the two beams 42 and 42 'do not touch the quartz plate 50 and the quartz plate 60 and the vibration thereof is not hindered. For this purpose, for example, the quartz thin plate 40-2
The thickness of the beam 42 and the beam 42 ′ is
0 is cut out to be thinner than the thickness of itself, and when the thin quartz plate 40 is joined to the quartz plate 50 and the quartz plate 60, a small space is formed between the quartz thin plate 40, the quartz plate 50 and the quartz plate 60. To

Referring to FIG. 4, the vibration of the bending-type tuning fork type quartz vibrator will be described .
Beams 42 and 42 ′ constituting the tuning fork of FIG.
Reverse, the case of no input has a single vibration speed V to the opposite phase, when the rotation angular velocity ω of such is illustrated in the tuning fork direction is applied, Coriolis force in a direction illustrated respectively the beam F on the = 2 mVω (m is the mass of the beam), and the beam is displaced in the direction of the Coriolis force F by an amount proportional to the angular velocity ω . Then, in FIG.
40 transducers, two beams 42 and 4
2 ′ are opposite to each other and have a simple vibration of velocity V in opposite phase.
In the case of no input, when an upward force F, that is, a linear acceleration in the figure is applied to the tuning fork, the beam bends downward.

Here, a block diagram of the variable capacitance type displacement detector shown in FIG. 5 will be referred to. The bending-type tuning-fork type crystal resonator illustrated and described with reference to FIG. 3A forms variable capacitors C1, C2, C3 and C4 of a variable capacitance type displacement detector. This will be further described with reference to FIG. 3B. The variable capacitance C1 includes a front electrode 43 formed on the beam 42 and a detection electrode 6 formed on the quartz plate 60.
The variable capacitance C2 is formed by the back electrode 33 formed on the beam 42 and the detection electrode 5 formed on the quartz plate 50.
1, the variable capacitor C3 is formed by the front electrode 43 'formed on the beam 42' and the detection electrode 61 'formed on the quartz plate 60, and the variable capacitor C4 is formed by the beam 4'.
It is formed by a back electrode 33 'formed on 2' and a detection electrode 51 'formed on the quartz plate 50. Variable capacitors C1, C2, C3 formed by this bending type tuning fork type quartz resonator
And C4 are connected in a differential bridge, and their connection terminals A and B are AC driven by an AC voltage oscillator 100.

In FIG . 4 (a), two pieces forming a tuning fork
Beam 42 and beam 42 'are simply out of phase with each other.
In the case of simple vibration of degree V, any variable capacitance C
No change in volume occurs. Therefore, beam 42 and beam 4
2 'Both differential bridge circuits are in a balanced state,
The voltages of the children C, D, C ′, D ′ are shown in FIG.
A simple oscillation output voltage waveform having a constant amplitude is obtained. However,
When a rotation at an angular velocity ω in the illustrated direction is applied, Coriolis force F in the illustrated directions is applied to the two beams 42 and the beam 42 ′, so that these beams are separated from each other in FIG.
As shown by the chain line in FIG.
You. The two beams 42 and 42 'are displaced more than
Then, the capacitance of the variable capacitor C1 increases and
On the other hand, the capacitance of the variable capacitor C2 decreases, while the variable capacitor C2 decreases.
4 increases and the capacitance of the variable capacitor C3 increases.
Decreases. Time of angular velocity ω opposite to the direction shown
When the rolling is applied, the capacitance of the variable capacitor C1 decreases.
The capacitance of the variable capacitor C2 increases with the
The capacitance of the variable capacitor C4 decreases and the capacitance of the variable capacitor C3 decreases.
The capacitance increases. Variable capacitance C1 to variable capacitance C4
6B, the voltages at the connection terminals C and D have a voltage waveform that is amplitude-modulated by the vibration frequency of the vibrator as shown in FIG. 6B.
As shown in FIG. 6C, the voltages at the connection terminals C ′ and D ′ have a voltage waveform that is amplitude-modulated by the vibration frequency of the vibrator. The voltage waveform shown in FIG. 6B and the voltage waveform shown in FIG. 6C have opposite phases.

Here, referring to FIG.
In order to explain the detection signal processing of the position detector, the beams 42 and
Of two sets of variable capacitance displacement detectors including
The difference between the detection signal outputs is obtained by the differential circuit 120, and both displacements are obtained.
The difference in the detection signal output of the detector is
Synchronous detection is performed by the synchronous detection circuit 130 at the frequency.
The output is input to the smoothing circuit 150 and the residual component of the driving AC voltage
Is smoothed. On the other hand, signal processing for acceleration
Inverting circuit 170 for sum of outputs of variable capacitance type displacement detector
Is obtained by the differential circuit 121 through the
The residual component of the driving AC voltage is smoothed. Below, the waveform diagram
A description will be given with reference to waveforms at various parts of the road. Above detection signal processing
Performs synchronous detection at the oscillation frequency of the crystal oscillation circuit 140
A synchronous detection circuit 130 is provided, and the polarity and direction of the angular velocity
Is determined. The voltages at points F, E, J, and H, which are the voltages resulting from half-wave rectification of these voltage waveforms by the half-wave rectifier circuit 110, are as shown in FIGS. 7A to 7D. The voltages at points G and K, which are the outputs of the differential circuit, are shown in FIG.
8 (a) and FIG. 8 (b), the voltage at the point L which is the output voltage of the differential circuit 120 with this input voltage is shown in FIG.
It is as shown in (c). Here, FIG.
(C) shows the case where the oscillation frequency of the vibrator and the voltage at the point L are in phase, depending on the polarity of the angular velocity ω. This is similar to FIG. When the oscillation frequency of the vibrator and the voltage at the point L are in opposite phases, the waveform is opposite to that of FIG. The voltage at the point N, which is the output voltage of the phase discriminator 130, is as shown in FIG.
The case opposite to that of FIG. 8 (c) is as shown in FIG. 9 (b). 9A and 9B, a straight line P indicates a voltage proportional to the angular velocity ω.

When a linear acceleration is applied to the vibrator, the vibrator bends as shown in FIG. In this case, the capacitances of the variable capacitors C1 and C3 both decrease, and as a result, the voltages at the connection points C and C 'increase as compared with those at the neutral point. That is, as shown in FIG. 10, (a) shows the voltages at points C and C ', and (b) shows the voltages at points D and D'. The voltages at points F, E, J and H obtained by half-wave rectification of these are shown in FIG.
This is as shown in FIGS. The voltage at the point R, which is the output voltage of the differential circuit 121, is shown in FIG.
1A is applied to the voltage at point G shown in FIG.
It is equivalent to the sum of the voltages at the point K shown in FIG. The voltage at this point R is as shown in FIG. Note that the addition cancels out the angular velocity component and becomes irrelevant to the acceleration measurement. Therefore, if the voltage in a state where the acceleration is zero is used as a reference, a signal changed by the acceleration can be obtained.

The above description relates to the case where the variable capacitance type displacement detector is driven by the AC voltage oscillator 100. When the drive is performed by the DC voltage, the following is obtained. That is, when an angular velocity is applied to the vibrator, the vibrator always has a vibration component also in the right-angle direction due to Coriolis force, so that an AC voltage is generated on the detection electrode even in a DC electric field. However, when acceleration is applied, if the frequency of the acceleration is low, it is difficult to generate a voltage at the electrode, and therefore, it is preferable to employ the AC voltage drive for detecting the acceleration signal.
You.

[0020]

As described above, according to the present invention, the quartz thin plate 40 constituting the tuning fork is replaced with the two quartz plates 5 from both sides thereof.
A sensor unit for detecting one-axis angular velocity / acceleration by forming a variable capacitance of a variable capacitance type displacement detector using a bending-type tuning fork type crystal resonator having a simple configuration of sandwiching a zero and a quartz plate 60. Therefore, it is possible to provide a one-axis angular velocity / acceleration sensor which is extremely simple mechanically, yet has small size, light weight, low cost, long life, and high reliability.

The present invention enables the position change of the two beams of the tuning fork to be detected and signal-processed independently by the variable capacitance type displacement detector and the electric circuit. The one-axis angular velocity can be accurately detected from the signal difference, and the one-axis acceleration can be accurately detected from the sum of the signals.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional example of a one-axis angular velocity / acceleration sensor.

FIG. 2 is a diagram illustrating a piezoelectric beam rotating body.

FIG. 3 is a view for explaining a bending type tuning fork type crystal resonator;
(A) is an exploded perspective view of the whole, and (b) is a perspective view of a tuning fork.

FIG. 4 is a view for explaining a vibration mode of a tuning fork of a bending type tuning fork type crystal resonator.

FIG. 5 is a block diagram of a variable capacitance type displacement detector.

6A and 6B are diagrams showing voltages at points in a variable capacitance type displacement detector, and FIG. 6A shows C, D, C ′, and D ′ when two beams are not displaced vertically. Point voltage, (b) is 2
C, D 'when the book beam vibrates vertically in a single direction
FIG. 4C is a diagram showing voltages at points C ′ and D when two beams vibrate in a single direction in the vertical direction.

7A and 7B are voltages obtained as a result of half-wave rectification of an output voltage waveform by a half-wave rectifier circuit, where FIG. 7A shows a voltage at a point F, FIG. 7B shows a voltage at a point E, FIG. (D) is a diagram showing the voltage at point H.

8 (a) is the voltage at point G, FIG. 8 (b) is the voltage at point K,
(C) is a diagram showing the voltage at point L.

9A and 9B show a voltage at a point N which is an output voltage of the phase discriminator. FIG. 9A is a diagram corresponding to FIG. 8A, and FIG.
The figure corresponding to (b).

10 (a) is a voltage at points C and C ′, and FIG.
D 'voltage.

11A is a voltage at a point F, FIG. 11B is a voltage at a point E,
(C) is a diagram showing the voltage at point J, and (d) is a diagram showing the voltage at point H.

12A is a voltage at a point G, FIG. 12B is a voltage at a point K,
(C) is a diagram showing the voltage at point R.

[Explanation of symbols]

 REFERENCE SIGNS LIST 40 Quartz thin plate 41 Quartz thin plate support frame 42 Beam 42 ′ beam 33 Back detection electrode 43 Front detection electrode 51 Detection electrode 61 Detection electrode 50 Quartz plate 60 Quartz plate 100 AC voltage oscillator

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01C 19/56 G01P 9/04 G01P 15/125

Claims (3)

(57) [Claims] 1. Water forming a tuning fork consisting of two beams
A thin crystal plate is sandwiched between two quartz plates from both sides,
The amount of displacement of one beam due to one axis angular velocity / acceleration is detected.
The output detection electrodes are two beams and two crystals on both sides.
Formed by a bending-type tuning fork-type quartz oscillator formed on a plate
Let the capacitance be the capacitance of the variable capacitance displacement detector,
Equipped with two sets of variable capacitance displacement detectors, bending type tuning fork type
Sufficiently high stability compared to the crystal oscillator frequency
2 sets of AC voltage oscillators for driving the displacement detector
The difference between the detection signal outputs of the variable capacitance displacement detectors
And two sets of variable capacitance displacement detectors
A single axis angle characterized by comprising a circuit for calculating the sum of forces
Speed / acceleration sensor. 2. The one-axis angular velocity / acceleration according to claim 1.
In the degree sensor, The two quartz plates are stiffer than the thin quartz plate, and the beam vibrates.
Keep a small gap around the beam to prevent interference
Hold the crystal sheet so that it only touches the crystal sheet support
A one-axis angular velocity / acceleration sensor, characterized in that: 3. The method according to claim 1, wherein
In one-axis angular velocity / acceleration sensor, Oscillation component and beam precession caused by application of angular velocity
Variable displacement component of beam due to acceleration and acceleration applied
These are detected as the AC signal output of the
Signal output Signal processing for angular velocity is performed by a differential circuit.
Input and calculate the difference between the outputs of the two sets of variable capacitance displacement detectors.
And apply the oscillation frequency of the crystal oscillation circuit to the synchronous detection circuit
And perform synchronous detection.
Signal components for acceleration and two sets of possible
The AC signal output of one of the variable capacitance displacement
Of the variable capacitance type displacement detector
Input of the other AC signal to the differential circuit via the inverting circuit.
To obtain the sum, and the residual component of the drive AC voltage is
1-axis angular velocity / acceleration sensor characterized by smoothing
Sa.