JPH1054724A - Angular velocity detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a torsional force from being generated within an oscillator by the Coriolis force generated according to rotation, and perform a highly efficient detection free from vibration leakage by arranging four parallel vibrating pieces one-side ends of which are commonly fixed so that the adjacent pieces have a substantially equal space. SOLUTION: An oscillator 1 is formed of a square pole fixing base 10, and four vibrating plates 2-5 fixed to the side surfaces thereof by non-elastic solder glass. The vibrating plates 2-5 are formed of thin monocrystal bases of quartz, and have the same plane form in which slender vibrating pieces 6-9 are protruded from one-side short edges of rectangular base parts, respectively. The vibrating pieces 6-9 are arranged so as to have the same distance from a virtual axis parallel to a rotating shaft having a detected angle speed and an equal space, and an equal space between the adjacent ones. An exciting circuit excites the vibrating pieces 6-9 so that each is vibrated in the same direction with the reverse phase to the vibrating piece opposed thereto, and in the orthogonal direction,to the vibrating piece adjacent thereto. Thus, no torsional force is generated in the commonly fixed part of the vibrating pieces 6-9 by the effect of the generated Coriolis' force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detecting device used for an automobile navigation system and attitude control, and more particularly to a vibration type angular velocity detecting device.

[0002]

2. Description of the Related Art Conventionally, there has been known a vibration type angular velocity detecting apparatus utilizing the fact that when a vibrating body is rotated, a new vibration corresponding to the rotational angular velocity is generated by Coriolis force. As a vibrator having four vibrating reeds, there is, for example, a so-called H-type vibrator disclosed in Japanese Patent Application Laid-Open No. 6-331362.

[0003]

In this type of H-type vibrator, various modes can be considered as vibration modes. In either case, the H-type vibrator is supported by either excitation vibration or vibration based on Coriolis force orthogonal to the vibration. The part is twisted. This torsional vibration is likely to cause vibration leakage to the outside, and may also cause noise.

[0004]

SUMMARY OF THE INVENTION An angular velocity detecting device according to the present invention is provided to solve such a problem, and includes a vibrator, an exciting means for exciting the vibrator, and an exciting means for exciting the vibrator. A detecting means for detecting the amplitude of the vibration based on the Coriolis force generated as the vibrator rotates; and an angular velocity calculating means for calculating the angular velocity of rotation from the magnitude of the amplitude detected by the detecting means. In the angular velocity detecting device described above, the vibrator includes four parallel vibrating pieces having one end fixed in common, and the four vibrating pieces are adjacent to each other at substantially equal distances from a virtual axis parallel to the rotation axis of the detected angular velocity. Are arranged so as to be substantially equidistant from each other. Further, the excitation means sets the four vibrating pieces in the same direction and in the opposite phase to the vibrating pieces facing each other via the virtual axis, and Are orthogonal directions It is intended to excite so.

Further, the exciting means excites any two adjacent vibrating bars among the vibrating bars in the same direction in opposite phases, and excites the remaining two vibrating bars in the same direction in opposite phases and the other two vibrating bars. Both of the vibrating pieces may be excited in opposite phases.

By oscillating the vibrating reeds in such a manner, the vibration is generated in the portion where the four vibrating reeds are fixed in common, also in the direction orthogonal to the exciting vibrations. Even from vibration to be detected by Coriolis force (detection vibration), the forces from the respective vibrating pieces cancel each other out, and no torsional force is generated.

[0007]

FIG. 1 is a perspective view showing a vibrator used in an angular velocity detecting device according to the present invention. The vibrator 1 has four vibrating plates 2 to 5 fixed to the four side surfaces of a fixed base 10 of a quadrangular prism with non-volatile solder glass or the like, respectively. The vibrating plates 2 to 5 are thin single crystal substrates made of quartz, and have the same shape in which elongated vibrating pieces 6 to 9 project from one short side of a rectangular base in a planar shape as shown in the figure.

FIG. 2 is a perspective view showing the diaphragm 2 as a representative of the diaphragms 2-5. Exciting electrodes 20a to 20d (note that the electrode 20c is on the back side and is not visible in this drawing) are provided at the four corners of the vibrating bar 6, respectively. In addition, detection electrodes 21a are provided on the four side surfaces of the vibrating piece 6.
To 21d (however, the electrodes 21c and 21d are not visible in this figure because they are on the back side). These electrodes have a two-layer structure of chromium and gold, and are obtained by depositing these metals on the surface of the resonator element 6 and then separating them appropriately using photolithography and patterning them into a desired shape. Can be Also,
Each electrode is electrically connected to one of the bonding pads (not shown) provided at the base of the diaphragm 2, and further connected to a signal processing circuit to be described later via a bonding wire or the like.

Here, a single crystal substrate of quartz constituting the diaphragm 2 will be described. Natural quartz is generally a columnar crystal, and the longitudinal central axis of the columnar crystal, ie, <00
01> The crystal axis is defined as a Z axis or an optical axis, and a line passing through the Z axis and perpendicular to each surface of the columnar crystal is defined as a Y axis or a mechanical axis. A line passing through the Z axis and orthogonal to the vertical ridge line of the columnar crystal is defined as an X axis or an electric axis.
The single crystal substrate used for the diaphragm 2 is a substrate called a Z plate, which is a single crystal substrate cut out in a plane perpendicular or substantially perpendicular to the Z axis. There are three sets of X-axis and Y-axis of the crystal which are orthogonal to each other.
The axis is aligned with the longitudinal direction of the vibrating bar 6, and the projecting direction of the vibrating bar 6 is matched with the + Y direction. The XYZ coordinate axes shown in FIG. 2 indicate this. The quartz used for the diaphragm 2 is an artificial quartz, but its structure is the same as a natural quartz.

Next, the Z-direction excitation operation of the resonator element 6 will be described with reference to FIG.
This will be described with reference to FIG. FIG. 4A is a cross-sectional view of the resonator element 6 taken along the XZ plane, and FIG. 4B is a perspective view illustrating a bending operation of the resonator element 6. Now, consider a state in which a voltage having a polarity as shown in FIG. That is,
A negative voltage is applied to the electrodes 20a and 20c, and a positive voltage is applied to the electrodes 20b and 20d. Since the piezoelectric effect of quartz does not appear in the Z-axis direction, ignoring the electric field in the Z-axis direction, the effective electric field that affects the piezoelectric effect is -X on the upper side as indicated by arrows 31 and 32, and lower on the lower side. Generates an electric field in the direction of + X. Due to the inverse piezoelectric effect, the crystal of quartz expands in the Y-axis direction when an electric field is applied in the positive direction of the X-axis, and contracts in the Y-axis direction when an electric field is applied in the negative direction of the X-axis. Therefore, in the state shown in FIG. 3A, the upper half of the vibrating reed 6 contracts and the lower half extends, so that the vibrating reed 6 bends upward. Electrodes 20a to 20
When the polarity of the applied voltage with respect to d is reversed, the resonator element 6 bends downward according to the same principle. By repeating this polarity reversal, the vibrating reed 6 becomes Z as shown in FIG.
Vibrates in the direction.

The detecting electrodes 21a to 21d are
Are electrodes for detecting the vibration amplitude in the X direction. FIG.
Is for explaining the detection principle. Vibrating piece 6
When vibrating in the X direction and bending in the + X direction as shown in FIG. 4B, the electrode 21b side of the vibrating reed 6 extends in the Y direction, and the electrode 21d side contracts in the Y direction. Due to the piezoelectric effect of the crystal, dielectric contraction in the Y direction causes dielectric polarization 41 in the X direction, and expansion in the Y direction causes dielectric polarization 42 in the opposite X direction.
As a result, positive charges collect on the electrodes 21a and 21c, and negative charges collect on the electrodes 21b and 21d. This charge amount becomes large as the bending becomes large. When the resonator element 6 bends in the -X direction, a polarity completely opposite to that described above appears based on the same principle. The vibration plates 3 to 5 have exactly the same structure as the vibration plate 2 including the crystal orientation and the electrode arrangement, and are fixed so that the + Z directions are all outward and the positions of the respective vibrating pieces in the Y direction are aligned. The base 10 is fixed to four side surfaces. Therefore, the vibrating bars 6 to 9 are parallel to each other and are all equidistant from the central axis 19 in the longitudinal direction of the fixed base 10.

FIG. 5 shows an excitation circuit 50, a detection circuit 60 and an angular velocity calculation circuit 70 according to the present embodiment. These circuits and electrodes 20a to 20d provided on the vibrating bars 6 to 9 are shown.
And FIG. 21 is a block diagram showing a connection relationship between the communication device and 21a-21d.

The excitation circuit 50 includes a current-voltage conversion circuit 51, an automatic gain control circuit 52, and a drive circuit 53.

The driving circuit 53 outputs a pulse wave having an amplitude corresponding to the output voltage value of the automatic gain control circuit 52 and having a predetermined repetition frequency as an excitation signal, and synchronizes the output signal with a signal having a phase shifted by 90 degrees. The detection circuit 64 outputs a detection signal as a detection signal.
, Two of the excitation electrodes of the vibrating bars 6 to 9 are selected and connected as shown. The remaining excitation electrodes of the vibrating bars 6 to 9 are connected to the input terminal of the current-to-voltage conversion circuit 51 via the terminal 55 in common with each other, so that they are fixed at the intermediate potential of the pulse wave output from the drive circuit 53. You. Under such a connection, an excitation signal having an excitation frequency close to the natural frequency of the resonator element is applied to the resonator elements 6 to 9.
, The vibrating bars 6 to 9 respectively have arrows 11 to 11
It is excited with a phase as represented by 14. That is,
The vibrating bars 6 and 8 are excited in opposite phases in the vertical direction in FIG. 1, and the vibrating bars 7 and 9 are excited in opposite phases in the left and right direction in FIG. Moreover, the vibrating bars 6 and 8
Is spread outward as shown by arrows 11 and 13, the vibrating pieces 7 and 9 are excited at a timing such that they close inward as shown by arrows 12 and 14.

The excitation vibration information of the resonator element is fed back via a current-voltage conversion circuit 51 and an automatic gain control circuit 52. The current-voltage conversion circuit 51 is a circuit that converts the amount of change in the charge generated in the excitation electrode by the piezoelectric effect accompanying the bending of the vibrating bars 6 to 9 in the Z-axis direction into a voltage value.

The automatic gain control circuit 52 receives the voltage signal output from the current-voltage conversion circuit 51, and decreases the output voltage value when the input voltage value increases, and increases the output voltage value when the input voltage value decreases. It works to be.
Therefore, when the excitation vibration amplitude of the vibrating bars 6 to 9 increases, the electric charge generated in the excitation electrode also increases, and the output voltage of the current-voltage conversion circuit 51 also increases. As a result, the output voltage value of the automatic gain control circuit 52 decreases, and the amplitude of the output pulse of the drive circuit 53 decreases. In this way, the amplitude of the pulse signal output from the drive circuit 53 is feedback-controlled, and the excitation amplitude of the vibrating bars 6 to 9 is always stable.

Next, the connection of the detection electrodes for detecting the vibration of the vibrating bars 6 to 9 in the X-axis direction and the detection circuit 60 will be described. The detection electrodes provided on the vibrating bars 6 to 9 are connected as shown in FIG. 5 and connected to terminals 65 and 66. When the vibrator 1 is rotated about the axis 19 while exciting the vibrating bars 6 to 9 in phases as indicated by arrows 11 to 14, vibration in the X-axis crystal direction based on the Coriolis force is as shown by arrows 15 to 18. Occurs in phase. The change in the electric charge as described with reference to FIG. 4 occurs in each detection electrode based on the X-direction vibration, and this change is detected by the detection circuit 60. The detection electrodes are connected such that charges of the same polarity are superimposed on the basis of the phase relationship with the excitation vibration.

The detection circuit 60 includes current-voltage conversion circuits 61 and 62, an operation amplification circuit 63, and a synchronous detection circuit 64.

The current-to-voltage conversion circuit 61 has a common input terminal connected to a total of eight electrodes, two of which are selected from the detection electrodes of the vibrating bars 6 to 9 as shown in FIG. Is a circuit that amplifies the amount of change in the electric charge at the electrode and converts it to a voltage value. The current-voltage conversion circuit 62 is a circuit that amplifies the amount of change of the electric charge at the remaining detection electrodes and converts it to a voltage value. . The operation amplification circuit 63 is a circuit which receives the output signals of the current-voltage conversion circuits 61 and 62 and amplifies the potential difference between the two signals, and the amplitude change of this output signal is proportional to the vibration amplitude change of the vibrating bars 6 to 9. doing.

The synchronous detection circuit 64 generates a pulse signal which is 90 degrees out of phase with respect to the excitation signal from the drive circuit 53 by using the AC voltage signal output from the operation amplification circuit 63, and uses the pulse signal as a detection signal. This is a circuit in which integration processing is performed after synchronous detection is performed, and an integration circuit is added to a normal synchronous detection circuit. Since the vibration in the X-axis direction due to the Coriolis force is 90 degrees out of phase with respect to the excitation, the synchronous detection and integration result in an integrated value of full-wave rectification. That is, the output signal voltage of the synchronous detection circuit 64 indicates the vibration amplitude in the X-axis direction due to the Coriolis force of the vibrating bars 6 to 9. Although the vibration in the X-axis direction includes a vibration due to the leakage of the excitation in the Z-axis direction, the vibration has the same phase as the excitation vibration, and thus becomes zero during synchronous detection.

The angular velocity calculation circuit 70 calculates a rotational angular velocity about the axis 19 of the vibrator 1 or an axis parallel to the axis based on the output signal of the detection circuit 60 indicating the vibration amplitude of the vibrating bars 6 to 9. This is a circuit for calculating based on a relational expression between the angular velocity and the Coriolis force.

Next, the operation of the angular velocity detecting device configured as described above will be described. The excitation circuit 50 includes the vibrating pieces 6 to 9
The driving circuit 53 outputs an excitation signal having a frequency substantially equal to the natural frequency of. Accordingly, the vibrating bars 6 to 9 self-excited due to the inverse piezoelectric effect. As shown by arrows 11 to 14, the vibration phases of the vibrating bars 6 to 9 are in the same direction and opposite phases to the vibrating bars in which the vibrating bars oppose each other via the shaft 19, and in the direction orthogonal to the adjacent vibrating bars. Excitation to become.

In this state, when the vibrator 1 rotates at an angular velocity ω about the axis 19 or an axis parallel thereto, each of the vibrating bars 6 to 9 applies a Coriolis force F expressed by F = 2 mV · ω. Are generated in the X crystal axis direction of each resonator element. Here, m is the mass of the resonator element, and V is the vibration speed. Due to the generation of the Coriolis force F, the vibrating pieces 6 to 9 vibrate in the X crystal axis direction with a phase shift of 90 degrees with respect to the vibration in the Z crystal axis direction.
The detection circuit 60 detects this vibration amplitude and supplies it to the angular velocity calculation circuit 70, which calculates ω based on F = 2 mV · ω.

The vibrator 1 has four parallel vibrating bars 6 to 9 whose one ends are fixed in common, and the four vibrating bars 6 to 9 are parallel to the rotation axis of the detected angular velocity. It is disposed so as to be substantially equidistant from the shaft 19 and to be substantially equidistant from each other, further in the same direction and the opposite phase to the vibrating piece opposed via the shaft 19, and in a direction orthogonal to the adjacent vibrating piece. It is excited to be That is, the vibrating bars 6 to 9
Is in the radial direction about the center axis 19 of the fixed base 10,
In addition, since the opposing members vibrate in opposite phases, no torsional force is generated on the fixed base 10. In addition, the detection vibration based on the Coriolis force is generated in the tangential direction (arrows 15 to 18) of the circle around the axis 19 with the rotation, but the adjacent vibrating pieces cancel out the torsional force. No twisting force occurs. As described above, according to the vibrator used in the present embodiment, no torsional force is generated by the excitation vibration or the detection vibration. Also, the center of gravity does not deviate from the axis 19. Therefore, there is no occurrence of vibration leakage to the outside due to torsion or movement of the center of gravity, and high detection efficiency can be maintained. This effect can be achieved by exciting the vibrating piece opposed via the shaft 19 in the same direction and the opposite phase, and in a direction orthogonal to the adjacent vibrating piece. Alternatively, excitation may be performed as indicated by arrows 15 to 18.

FIG. 6 is a perspective view showing a vibrator 101 used in the second embodiment of the present invention. The vibrator 101 has vibration plates 102 and 103 fixed to the upper and lower surfaces of an intermediate substrate 110 which also serves as a fixed base and a wiring substrate. Each of the vibration plates 102 and 103 has two vibrating pieces 106, 107, 108 and 109 are provided integrally. Since the vibration plates 102 and 103 and the substrate 110 are bonded and fixed with a non-volatile solder glass or the like, even when housed in a vacuum-sealed container to suppress vibration leakage, even when the polymer adhesive is used. No such gas is generated.

Each of the vibration plates 102 and 103 is a Z plate made of a single crystal of quartz, and the intermediate substrate 110 is also made of a quartz substrate. Thus, by forming the diaphragm and the intermediate substrate from the same material, unnecessary stress is not generated in the diaphragm due to a temperature change or the like. Therefore, vibration leakage due to unnecessary stress can be prevented.

The diaphragms 102 and 103 are tuning fork-type diaphragms each having two vibrating pieces, and have the same shape. Vibrating pieces 106, 107, 108 and 109
All project in the Y-crystal axis direction of the crystal, and are provided with an excitation electrode and a detection electrode. This vibrator 1
In 01, the four vibrating bars 106, 107, 108, and 109 are in the same direction and in phase with the vibrating bars facing each other via the central axis (a virtual axis substantially equidistant from the four vibrating bars), Excitation is performed so as to be in the same direction and opposite phase with the adjacent resonator element. Here, the vibrating bars 106 and 10
7 are excited in a direction opposite to each other in the X crystal axis direction (see arrows 111 and 112), and the vibrating pieces 108 and 109 are in a phase opposite to each other in the X crystal axis direction and also in a phase opposite to the vibrating pieces 107 and 106 located above, respectively. (See arrows 113 and 114). The excitation electrodes are arranged on four side surfaces of the resonator element. On the other hand, the detection electrodes are arranged at four corners of each resonator element. The relationship between the excitation direction and the excitation electrode, and the relationship between the detected oscillation direction and the detection electrode are shown in FIGS.
, And is not described here in detail.

On both sides of the intermediate substrate 110, wiring pins 1 are provided.
21a to 121h are fitted and fixed. Vibrating piece 106
The excitation electrode and the detection electrode of No.
Are connected to the wiring pins 121a to 121h via the wiring on the intermediate substrate 110 and the wiring on the intermediate substrate 110, and are connected to the externally provided excitation circuit and detection circuit via the wiring pins 121a to 121h. The wirings on the diaphragms 102 and 103 and the wiring on the intermediate substrate 110 are connected by bonding wires. The wiring on the diaphragm and the intermediate substrate and the bonding wires are not shown. The wiring pins 121a to 121h are fitted into eight through holes provided in the hermetic stem 120 such that the tips protrude from the back surface, and are hermetically fixed with a nonvolatile fixing material. With this configuration,
The wiring pins 121a to 121h can also be used as means for attaching and fixing the vibrator 1.

When the vibrator 1 is rotated about an axis parallel to the longitudinal direction of the vibrating piece while exciting the vibrating pieces 106 to 109 of the vibrator 1 as shown by arrows 111 to 114, the vibrating pieces become arrows 115 to 118. Vibration due to the Coriolis force occurs in the indicated direction and phase, so that the detection electrode changes in charge. This is detected by the detection circuit as in the first embodiment, and the angular velocity calculation circuit calculates the angular velocity based on the result.

Also in this embodiment, no torsional force is generated for both the excitation vibration and the detected vibration, and the center of gravity does not move from the center axis.

In each of the above embodiments, the vibration plate is formed by patterning a quartz Z plate, but other piezoelectric materials such as lead zirconate titanate (PZT), lithium niobate and lithium tantalate may be used. May be used. Furthermore, the diaphragm may be a simple diaphragm such as stainless steel, and may be vibrated and detected using electrostriction means instead of the electrodes.

[0032]

As described above, according to the angular velocity detecting device of the present invention, when the vibrating piece of the vibrator is excited, the Coriolis force generated by the excitation vibration and the rotation. Therefore, no torsional force is generated inside the vibrator, and the center of gravity does not deviate from the center axis of the detection rotation.
Therefore, there is no vibration leakage due to the torsional force or the movement of the center of gravity, and the detection of ω can be achieved with high efficiency.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a vibrator used in an angular velocity detecting device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a diaphragm used for the vibrator.

FIG. 3 is a diagram for explaining an excitation operation of a resonator element in a Z-axis direction.

FIG. 4 is a diagram for explaining an X-axis direction vibration detection operation of the resonator element.

FIG. 5 is a block diagram showing processing circuits according to the first embodiment and connections between the processing circuits and electrodes provided on a resonator element.

FIG. 6 is a perspective view showing a vibrator used in an angular velocity detecting device according to a second embodiment of the present invention.

[Explanation of symbols]

1, 101: vibrator, 2 to 5, 102, 103: vibrating plate, 6 to 9, 106 to 109: vibrator, 10: fixed base,
110: intermediate substrate, 120: stem, 121a to 121
h… Fixing / wiring pins.

Claims (2)

[Claims] A vibrator; an exciting unit for exciting the vibrator; and a detection unit for detecting an amplitude of vibration based on Coriolis force generated by rotation of the vibrator excited by the exciting unit. Means and an angular velocity calculating means for calculating the angular velocity of rotation from the magnitude of the amplitude detected by the detecting means, wherein the vibrator includes four parallel vibrators having one end commonly fixed. The four vibrating bars are arranged so as to be substantially equidistant from each other at a substantially equal distance from an imaginary axis parallel to the rotation axis of the detected angular velocity, and to be adjacent to each other at substantially equal intervals. An angular velocity characterized in that the two vibrating bars are excited in the same direction and in opposite phase with respect to the vibrating bars facing each other via the virtual axis, and in a direction orthogonal to the adjacent vibrating bars. Detection device. 2. A vibrator, exciting means for exciting the vibrator, and detection for detecting an amplitude of vibration based on Coriolis force generated by rotation of the vibrator excited by the exciting means. Means and an angular velocity calculating means for calculating the angular velocity of rotation from the magnitude of the amplitude detected by the detecting means, wherein the vibrator includes four parallel vibrators having one end commonly fixed. And the four vibrating bars are arranged so as to be substantially equidistant from each other at a substantially equal distance from an imaginary axis parallel to the rotation axis of the detected angular velocity. Are in the same direction and in phase with the vibrating pieces that are opposed to each other via the virtual axis,
An angular velocity detecting device for exciting adjacent vibrating bars in the same direction and in opposite phase.