JP2004333460A - Oscillating gyroscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combination of excitation mode suitable for multi-axis detection with a gyroscope, using a tripod tuning fork, and to provide the excitation technology. <P>SOLUTION: The oscillation gyroscope has a profile of a tripod tuning fork comprising three oscillating legs substantially parallel to each other. The gyroscope comprises an oscillating body, having an HS mode in which both outer legs simultaneously open/close in the X direction, a T mode in which both outer legs are reversely displaced in the Z direction, and an HA mode in which both outer legs are displaced in the same direction, in the X direction, while a middle leg is displaced in the opposite direction, as available oscillation modes, where the Z axis being in a direction normal to the plane of tripod, the Y axis being in a direction parallel to the tuning fork axis, and the X axis being in a direction orthogonal to the Z axis and Y axis; and also comprises a drive circuit means for oscillating both modes, while keeping a specified phase difference, and the Coriolis force detecting means which detects distortion generated at each oscillation leg by the Coriolis force, generated by the rotational movement acting on the oscillating body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vibratory gyroscope. More specifically, the present invention relates to a multi-axis vibratory gyroscope using a tripod type tuning fork. Note that a tripod-type tuning fork refers to a vibrating body that includes three cantilevered vibrating bodies protruding in the same direction substantially in parallel from a common base and configured to support using the base. And
[0002]
[Prior art]
The material and shape of the tripod tuning fork are substantially common to the present invention and the prior art, and have a general shape as shown in the plan view of FIG. (However, the shape of the electrode film varies depending on the purpose.) In the figure, reference numeral 1 denotes a tripod tuning fork, which is cut out from a flat material such as quartz or piezoelectric porcelain. Reference numeral 2 denotes a base on which three parallel vibrating legs are formed. Each of the outer legs 3 and 4 is formed in a symmetrical shape with an outer leg, and may have a protrusion (a bent portion whose mass is eccentric from the axis) at the tip end as shown in the figure.
[0003]
Reference numeral 5 denotes a middle leg, whose length is slightly longer to balance the oscillating mass when the outer legs 3, 4 have a projection and the leg cross section is equal to the cross section of the middle leg 5. To define the direction with respect to the tuning fork, X, Y, and Z orthogonal coordinate axes are set as shown in the figure. The Z axis is perpendicular to the plate surface, the Y axis is in the axial direction of each leg parallel, and the X axis is in the width direction of each leg. When a plate close to a quartz Z-cut plate is used as the material of the tripod tuning fork 1 (may be tilted several degrees for characteristic adjustment), the X, Y, and Z axes are the so-called electric axes, mechanical axes, and light axes of the quartz material. Approximately corresponds to the axis.
[0004]
Next, a basic (lowest order) vibration mode that can occur in a tripod tuning fork will be described. There are four types: (1) HS mode in which both outer legs 3, 4 open and close simultaneously in the X direction (similar to a normal two-leg tuning fork), middle leg 5 does not move, (2) Both outer legs (3) a T mode in which the outer legs 3, 4 are displaced in the same direction in the Z direction and the middle leg 5 is displaced in the opposite direction; In the HA mode, the outer legs 3 and 4 are displaced in the same direction in the X direction, and the middle leg 5 is displaced in the opposite direction. Note that three related to the conventional example are the HS mode, the V mode, and the HA mode, and three related to the present invention are the HS mode, the T mode, and the HA mode.
[0005]
The operation of the vibratory gyroscope using a tripod type tuning fork will be briefly described. When the tripod tuning fork is vibrating constantly in any of the above vibration modes and the entire vibration system is rotated around a certain rotation axis at a certain angular velocity, the Coriolis acceleration causes an apparent force on the vibrating mass. Occurs. The magnitude and direction of the Coriolis force is twice the vector product of the angular velocity and the momentum of the oscillating mass. The Coriolis force is generated in each of the vibrating legs, and the phase thereof coincides with the vibration speed, so that the vibration displacement is shifted by 90 °. Therefore, if the vibrations of each leg are detected in a piezoelectric manner by appropriately combining them and the detection output is rectified by the synchronous detection means in consideration of the phase, the Coriolis force, that is, the components ωx, ωy, ωz of the angular velocity in the direction of the vibration body coordinate axis are obtained. A proportional direct current is obtained.
[0006]
[Problems to be solved by the invention]
In a conventional vibrating gyroscope (for example, using a bar-shaped vibrating body or a two-legged tuning fork), the angular velocity that can be detected by one vibrating body is one direction (one axis). The vibrator can detect two- or three-axis angular velocity components. This is desirable because it is extremely effective in increasing the number of functions, miniaturization, and cost reduction of the vibration gyroscope itself and the device in which it is incorporated.
[0007]
In order to detect a multi-axis angular velocity component, not one vibration mode for applying the angular velocity is excited but a plurality of vibration modes, and the distortion of the vibration due to the Coriolis force generated in each vibration mode is detected. The phases of a plurality of vibration modes to be excited are shifted so that the distortion effect due to each vibration mode can be detected separately. In the proposed conventional example, the HS mode and the V mode are excited with a phase shift of 90 °. As a result, the tips of the outer legs perform a circular motion or an elliptical motion. When ωx acts on the V mode, the amplitude of the HS mode changes due to the Coriolis force Fcx, and when ωy acts on the V mode, the HA mode is generated by the Coriolis force Fcy and the middle leg vibrates. When ωz acts on the HS mode, the Coriolis force Fcz also generates the HA mode, and the middle leg vibrates. The signals of the middle legs in the latter two HA modes are separated by performing synchronous detection of two systems with shifted phases with respect to the detection signals of the middle legs using the phase difference between the basic V and HS modes. .
[0008]
However, it was later found that the above-mentioned conventional example had a drawback. In general, in order to excite the two modes with phases shifted from each other, it is conceivable to provide an appropriate difference between the natural frequencies of the two modes and to excite them at one or an intermediate frequency. FIG. 14 shows an example of a tripod tuning fork (made of quartz, the basic dimensions of each part are in mm, the plate thickness z = 0.3, the base x = 2.1, y-4.0, the width x of both outer legs and slits) = 0.3, 4.2 from the slit bottom to the tip of the outer leg, x = 0.8 from the slit surface of the bent portion to the tip, and the width of the bent portion y = 0.3). This is a result of a simulation, in which vibration displacement (tip amplitude) ux (HS mode) and ui (V mode) of one outer leg, and a phase difference between the two are plotted with respect to a frequency change.
[0009]
From FIG. 15, it was found that the vibration displacement in the HS mode was extremely smaller than that in the T mode (almost 1/10) at the frequency at which the phase difference between the two modes was 90 °. (Even when the frequency difference was given by changing the other parameters, the result was almost the same.) When the frequencies of both modes were made closer, the amplitude difference was reduced, but the frequency difference was limited to almost 50 Hz. This is because both modes are coupled modes, so circular motion of the outer leg or elliptical motion close to a circle cannot be obtained, the difference in angular velocity sensitivity between both modes is large, and a high-sensitivity multi-axis gyroscope is It is shown that it is difficult to realize by a method of self-oscillating both the HS mode and the V mode at the frequency of.
[0010]
An object of the present invention is to provide a multi-axis vibratory gyroscope with high sensitivity by combining an improved vibration mode in a gyroscope using a tripod tuning fork as a vibrator. Yet another object is to provide an excitation technique for the vibration mode.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a vibration gyroscope of the present invention has the following features.
(1) An outline of a tripod-type tuning fork having three substantially parallel vibrating legs is provided. The Z-axis extends in a direction perpendicular to the tripod surface, the Y-axis extends in a direction parallel to the tuning-fork axis, and the Z-axis and the Y-axis. When the X-axis is taken in a direction perpendicular to the direction, the HS mode in which both outer legs are simultaneously opened and closed in the X direction, the T mode in which both outer legs are displaced in the opposite direction in the Z direction, and the outer legs in the X direction are the same. A vibrating body having an HA mode in which the center leg is displaced in the opposite direction and the center leg is displaced in the opposite direction, a driving circuit means for vibrating the two modes, and a rotational motion acting on the vibrating body. Coriolis force detecting means for detecting distortion generated in each of the vibrating legs due to Coriolis force.
[0012]
The vibration gyroscope of the present invention may further have the following features.
(2) One oscillation circuit is provided for driving the HS mode and the T mode at the same frequency.
[0013]
In order to achieve the above object, a vibration gyroscope of the present invention has the following features.
(3) A tripod-type tuning fork having three substantially parallel vibrating legs is formed. The Z-axis extends in a direction perpendicular to the tripod surface, the Y-axis extends in a direction parallel to the tuning-fork axis, and the Z-axis and the Y-axis. When the X-axis is taken in a direction perpendicular to the direction, the HS mode in which both outer legs are simultaneously opened and closed in the X direction, the T mode in which both outer legs are displaced in the opposite direction in the Z direction, and the outer legs in the X direction are the same. And the middle leg is displaced in the opposite direction as a possible vibration mode. The HS mode and the T mode both have a vibrating body given a predetermined natural frequency close to each other. Drive circuit means for oscillating the modes while maintaining a phase difference of about 90 ° from each other, and Coriolis force for detecting distortion generated in the three vibrating legs due to Coriolis force generated by rotational movement acting on the vibrating body Detecting means, wherein the Coriolis force detecting means is a T mode First detection circuit means for detecting the vibration of the HA mode caused by ωx acting, second detection circuit means for detecting a change in the T mode caused by ωy acting on the HS mode, and action on the HS mode And at least two of the third detection circuit means for detecting the HA mode vibration caused by ωz.
[0014]
The vibration gyroscope of the present invention may further include at least one of the following features.
(4) The excitation circuit means has a circuit configuration for exciting the HS mode, and the T mode is automatically given a natural frequency slightly different from that of the HS mode, so that the T mode automatically has a phase difference of about 90 °. Be driven
[0015]
(5) The excitation circuit means includes an oscillation circuit for exciting the T mode (or HS mode) and a circuit means for generating an excitation output having a phase substantially 90 ° different from the excitation output of the T mode (or HS mode). Driving the HS mode (or T mode) with the latter excitation output.
[0016]
(6) The detection circuit means includes the first detection circuit means and the second detection circuit means using an HA mode generated by different angular velocities ωx and ωz, and the first detection circuit means and the second detection circuit means The second detection circuit means separates and detects ωx and ωz by performing synchronous detection with a phase shift of 90 ° from each other.
[0017]
(7) The piezoelectric material of the vibrator is quartz.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the principle operation of the present invention and its advantages will be comprehensively described.
In the present invention, the HS mode and the T mode are used in combination for driving a tripod tuning fork. (Referred to as HS + T mode) FIG. 16 is a graph of a forced vibration response simulation showing the phase difference between the vibration displacement and vibration of the outer leg in the HS and T modes with respect to the drive frequency. In this example, the width of both outer legs was x = 0.275 mm (the length of the middle leg was y = 4.3 mm, and the other basic dimensions were the same as the conventional example).
[0019]
As shown in FIG. 16, in this example, the frequencies of both modes could be made very close. This is because both modes are not combined modes. In addition, it was found that a driving frequency at which the vibration displacements ux and uz are substantially equal exists near the T-mode resonance point at a phase difference of 90 °. In addition, the magnitude of the vibration displacement at that point is about 35 times larger than that of the conventional HS mode and about 5.5 times larger than the conventional V mode of the T mode, and the vibration trajectory of the outer leg is also a circular motion. And became extremely advantageous for improving the detection sensitivity.
[0020]
FIG. 11 is a line drawing showing two vibration modes used in the present invention. FIG. 11 (b) shows a T mode, FIG. 11 (c) shows an HS mode, and FIG. The resulting drive mode (T + HS mode) shows a state in which the ends of both outer legs are performing a combined circular motion.
[0021]
Next, the detection operation of the angular velocity will be described with reference to FIGS. (A) of each figure shows a fundamental vibration mode that is driven steadily irrespective of the phase difference, and (b) of each figure shows angular velocities ωx, ωy, supposed to act on that mode. ωz, and each figure (c) shows the resulting Coriolis forces Fcx, Fcy, Fcz (proportional to the instantaneous speed of the vibration of each leg and appears in a direction orthogonal to the speed and the angular speed) and generated by them. , A vibration mode to be detected.
[0022]
1 to 3 relate to a first embodiment of the vibrating gyroscope of the present invention. FIG. 1 is a plan view including an electrode film of a vibrating body, and FIG. 2 is an AA showing its electrode arrangement and connection. FIG. 3 is a block diagram showing a configuration of the excitation and detection circuit. Note that, for items common to the above-described conventional example, redundant description will be omitted below.
[0023]
1 and 2, the electrode film 6 of the outer leg 3 is divided into four surfaces around the leg, the electrode film 7 of the outer leg 4 is divided into only the upper and lower surfaces of the leg, and the electrode film of the middle leg 5 is divided. The membranes 8 are provided on four surfaces around the legs. In the case of a Z-cut plate made of quartz material, generally, an electrode film provided on only the upper and lower surfaces of the outer leg by dividing the leg name in parallel to the hand direction is suitable for T-mode driving / detection. The provided electrode film is suitable for driving and detecting in the HS mode or the HA mode. The conductor patterns provided on the surface of the vibrating body for connecting or connecting the electrode films are not shown.
[0024]
In FIG. 2 and FIG. 3, Gnd and Ref are terminals for applying a signal reference potential (the potential of Ref may be intermediate between Gnd and the power supply potential, but in this example, it is assumed to be equal to Gnd, and in the circuit diagram of FIG. Denotes a Ref terminal), Dr denotes a drive terminal for exchanging a drive (excitation) signal with the circuit side, and Dt1 and Dt2 denote detection terminals each containing a signal due to Coriolis force. FIG. 3 shows only basic circuit blocks, and does not show circuits that act as corrections. The connection arrows indicate the direction in which the signal flows. In the circuit operation, the outer leg 3 is excited in the HS mode by the driving terminals Dr and Gnd connected to the two-terminal oscillation circuit 11.
[0025]
The T mode is also generated simultaneously with a phase difference of approximately 90 ° due to a slight frequency difference between the two modes. Note that it is desirable that the T mode be generated at the resonance frequency or that the amplitude be obtained in both modes at the same level. For this purpose, a circuit means or an element for shifting the HS mode drive output obtained from the oscillation circuit 11 with respect to the oscillation phase of the same mode is appropriately added around the oscillation circuit, or the resonance frequency difference between the two modes is determined by a tripod tuning fork. It can be adjusted by the design.
[0026]
The AGC circuit 12 controls the drive output of the oscillation circuit 11 and stabilizes the amplitude of the fundamental vibration. The synchronous detection circuit 13x obtains the detection signal of the center leg 5 from the Dt1 terminal, performs synchronous detection on the detection signal from the DGC terminal (shifts the phase if necessary) from the AGC circuit 12, and obtains the angular velocity ωx To obtain an output ωxout proportional to.
Since the detection signal obtained from the Dt1 terminal of the center leg 5 includes a vibration component related to the angular velocity ωz in a form having a phase difference of 90 ° from ωx as shown in FIG. 10, this signal is subjected to AGC by the synchronous detection circuit 13z. A phase shift circuit 15 creates a synchronous detection signal by shifting the signal of the circuit 12 by 90 °, and supplies it to a synchronous detection circuit 13z to obtain an output ωzout proportional to the angular velocity ωz.
[0027]
Since the signal obtained from the detection terminal Dt2 includes a T-mode signal and a drive signal proportional to ωy in FIG. 9, first, the difference between the two is obtained by the differential amplifier 14 and ωxout is obtained. Similarly, ωyout can be obtained using the synchronous detection circuit 13y.
[0028]
4 to 6 show an electrode arrangement, connection, and a drive / detection circuit according to a second embodiment of the present invention. FIG. 4 shows not only the front surface (a) of the tripod tuning fork 1 but also the rear surface (b) of the tripod tuning fork 1 inverted with respect to the axis P. Further, regarding the symmetry axis (not shown) of the tripod tuning fork, the electrodes of both outer legs have two different arrangements of two planes (upper and lower Z planes) and four surrounding planes. , And CC, and FIG. 5 includes connections. The electrode of the cross section BB and the electrode of the cross section CC are partially continuous with each other, thereby simplifying the wiring electrode pattern.
[0029]
The feature of the second embodiment resides in that both outer legs have electrodes capable of driving and detecting the T mode, and otherwise operates substantially the same as the first embodiment. Therefore, the configuration and operation of the oscillation / detection circuit of FIG. 6 are substantially the same as those of the circuit of FIG. The difference is that the detection signals of the two legs obtained from the Dt2 and Dt3 detection terminals are added by the addition circuit 16 before use.
[0030]
FIGS. 7 to 9 show an electrode arrangement, connection, and a drive / detection circuit according to a third embodiment of the present invention. The feature of the present embodiment is that the electrodes 6d and 7d for T mode (section DD section) and the electrodes 6e and 7e for HS mode (section EE section) are longitudinally arranged on both outer legs 3 and 4. That is, they are provided separately in the directions. Although the number of electrodes increases and the wiring pattern becomes complicated, for example, the lead lines from the electrodes 6e and 7e on the tip side of the leg may be passed through the gap between the parallel electrodes 6d and 7d on the root side of the leg or the side surface of the outer leg. To the base 2 side. Further, it is possible to provide headband-type electrodes around the legs to connect the electrodes on the opposite surfaces, or to share the Gnd line of the HS electrode and the T electrode to reduce the number of lead lines. The constricted portion 9 provided in the base 2 is provided to facilitate the occurrence of T-mode vibration.
[0031]
In the drive / detection circuit (FIG. 9), the T-mode electrodes 6d and 7d (Gnd and Dr1 terminals) are directly connected to the oscillation circuit 11 to excite at the T-mode resonance frequency (natural frequency). The drive output is supplied to the electrodes 6e and 7e (Dr2 terminal) for the HS mode after being shifted by approximately 90 ° by the drive phase shift circuit 17, so that the HS mode is also driven at the resonance frequency of the T mode. The characteristic is that it is trying to obtain the amplitude of The operation of detecting the angular velocity is the same as that of the other embodiments, but the oscillation circuit 11 of FIG. 9 excites the T mode, and the oscillation circuits 11 of FIGS. 3 and 6 of the other embodiments excite the HS mode. Therefore, in each embodiment, the phase relationship between the drive signal obtained from the AGC circuit 12 and the synchronous detection signal required to detect a certain angular velocity component differs by 90 °. Taking this into account, the insertion position of the phase shift circuit 15 is different.
[0032]
In each of the above embodiments, the single oscillation circuit generates the fundamental vibration in both the HS mode and the T mode. However, the fundamental vibration in the two modes may be driven at different frequencies. FIG. 10 is a block diagram of a drive / detection circuit according to the fourth embodiment. As the vibrating body in this embodiment, similarly to the vibrating body of the third embodiment, a vibrating body provided with driving and detecting electrodes in both the HS and T modes for each mode is used. In FIG. 10, a dedicated oscillation circuit for driving each mode at a different frequency is provided, and the oscillation circuit 11a is connected to the Dt1 terminal and drives the T mode. The oscillation circuit 11b is connected to the Dt2 terminal and drives the HS mode. The configuration of the angular velocity detection circuit is similar to that of the circuit part of the third embodiment, except that a signal for synchronous detection is obtained from the fundamental mode drive signal used by the angular velocity component.
[0033]
Embodiments of the present invention are not limited to the examples described above. The shape and dimensions of the tripod tuning fork and the material of the vibrating body (for example, another piezoelectric crystal, piezoelectric porcelain, or metal with a piezoelectric element attached thereto) can be used. Also, various arrangement structures of the electrode film and the lead lines (for example, the T-mode electrodes are provided on the left and right sides (X plane) of the leg instead of the upper and lower surfaces [Z plane]), and further the configuration of the drive circuit and the detection circuit are various. Changes or improvements are allowed. For example, a filter for inserting a logic circuit for phase adjustment in a small range or an analog element such as L, C, or R at an arbitrary position and appropriately amplifying a signal is provided. Alternatively, not only detection of Coriolis force but also use of a part of the detection signals such as Dt1 and Dt2 as a feedback signal for assisting oscillation (the oscillation circuit may have three terminals) may be considered.
[0034]
【The invention's effect】
In the present invention, since the HS mode and the T mode are used in combination, it is possible to detect angular velocity components of two or three axes. Further, even when driven at a single frequency, a sufficiently large amplitude is obtained in both modes, and there is an effect that a multi-axis gyroscope having a simple configuration and high sensitivity to the angular velocity of each axis can be obtained. In addition, since the middle leg is not moved in principle in both modes, the middle leg can be used exclusively for detection, and the circuit configuration can be simplified.
[Brief description of the drawings]
FIG. 1 is a plan view including an electrode film of a vibrating body according to a first embodiment of a vibration gyroscope of the present invention.
FIG. 2 is a sectional view taken along the line AA in FIG. 1, showing electrode arrangement and connection of the vibrating body according to the first embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of an excitation and detection circuit according to the first embodiment of the present invention.
FIG. 4 is a plan view showing the vibrating body according to a second embodiment of the vibrating gyroscope of the present invention, including the arrangement of electrode films.
FIGS. 5A and 5B are a sectional view taken along the line BB and a sectional view taken along the line CC in FIG. 1, showing electrode arrangement and connection of the vibrating body according to the second embodiment of the present invention.
FIG. 6 is a block diagram illustrating a configuration of an excitation and detection circuit according to a second embodiment of the present invention.
FIG. 7 is a plan view showing a vibrating body according to a third embodiment of the vibration gyroscope of the present invention, including an arrangement of electrode films.
8A and 8B are a sectional view taken along the line DD and a sectional view taken along the line EE in FIG. 1, showing the arrangement and connection of electrodes of the vibrating body according to the third embodiment of the present invention.
FIG. 9 is a block diagram illustrating a configuration of an excitation and detection circuit according to a third embodiment of the present invention.
FIG. 10 is a block diagram illustrating a configuration of an excitation and detection circuit according to a fourth embodiment of the present invention.
FIG. 11 is a schematic plan view for explaining two vibration modes of a tripod tuning fork used in the present invention.
FIGS. 12A and 12B are schematic diagrams for explaining the relationship between the driving and the detecting operation, wherein FIG. 12A is a T driving mode, FIG. 12B is an angular velocity ωx acting on the driving mode, and FIG. 12C is generated by a Coriolis force Fcx. This is the HA vibration mode.
FIGS. 13A and 13B are schematic diagrams for explaining the relationship between the driving and the detecting operation. FIG. 13A shows the HS driving mode, FIG. 13B shows the angular velocity ωy acting on the driving mode, and FIG. 13C shows the angular velocity ωy generated by the Coriolis force Fcy. This is the T vibration mode.
FIGS. 14A and 14B are schematic diagrams for explaining the relationship between the drive and the detection operation, wherein FIG. 14A is an HS drive mode, FIG. 14B is an angular velocity ωz acting on the drive mode, and FIG. 14C is generated by a Coriolis force Fcz. This is the HA vibration mode.
FIG. 15 is a graph showing the phase difference between the vibration displacement and the vibration of the outer leg in the HS and V modes with respect to the driving frequency in the conventional example.
FIG. 16 is a graph showing the phase difference between the vibration displacement and the vibration of the outer leg in the HS and T modes with respect to the drive frequency in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tripod tuning fork 2 Base 3, 4 Outer leg 5 Middle leg 6, 7, 7d, 7e, 8, 8d, 8e Electrode film 9 Constriction part 11, 11a, 11b Oscillation circuit 12 AGC circuit 13x, 13y, 13z Synchronous detection circuit 14 Differential amplifier 15 Phase shift circuit 16 Addition circuit 17 Drive phase shift circuit Dr, Dr1, Dr2 Drive terminal Dt1, Dt2 Detection terminal Gnd, Ref Reference terminal E Electric field Fcx, Fcy, Fcz Coriolis force u3, u4, u5 Leg velocity component X, Y, Z coordinate axes

Claims (7)

The shape of a tripod-type tuning fork having three substantially parallel vibrating legs is provided. The Z-axis is perpendicular to the tripod surface, the Y-axis is parallel to the tuning-fork axis, and the Z-axis is orthogonal to the Y-axis. When the X axis is taken in the direction, the HS mode in which both outer legs are simultaneously opened and closed in the X direction, the T mode in which both outer legs are displaced in the opposite direction in the Z direction, and the two outer legs are displaced in the same direction in the X direction. A vibrating body having an HA mode in which the center leg is displaced in the opposite direction as a possible vibration mode, a driving circuit means for vibrating both modes, and a Coriolis force generated by a rotational motion acting on the vibrating body. A vibratory gyroscope comprising a Coriolis force detecting circuit for detecting distortion generated in each vibrating leg. 2. The vibratory gyroscope according to claim 1, further comprising one oscillation circuit means for driving said HS mode and said T mode at the same frequency. The shape of a tripod-type tuning fork having three substantially parallel vibrating legs is provided. The Z-axis is perpendicular to the tripod surface, the Y-axis is parallel to the tuning-fork axis, and the Z-axis is orthogonal to the Y-axis. When the X axis is taken in the direction, the HS mode in which both outer legs are simultaneously opened and closed in the X direction, the T mode in which both outer legs are displaced in the opposite direction in the Z direction, and the two outer legs are displaced in the same direction in the X direction. The middle leg has an HA mode in which the center leg is displaced in the opposite direction as a possible vibration mode. The HS mode and the T mode are both a vibrator given a predetermined natural frequency close to each other, and the two modes are mutually connected. Drive circuit means for vibrating while maintaining a phase difference of about 90 °, and Coriolis force detecting means for detecting distortion generated in the three vibrating legs due to Coriolis force generated by rotational movement acting on the vibrating body. Including, the Coriolis force detecting means operates in T mode First detection circuit means for detecting the vibration of the HA mode caused by ωx, second detection circuit means for detecting the change of the T mode caused by ωy acting on the HS mode, and the HS mode. A vibration gyroscope including at least two of the third detection circuit means for detecting the HA mode vibration caused by ωZ. The excitation circuit has a circuit configuration for exciting the HS mode, and the T mode is automatically driven with a phase difference of approximately 90 ° by giving a slightly different natural frequency from the HS mode. The vibratory gyroscope according to any one of claims 1 to 3, wherein The excitation circuit means includes an oscillation circuit for exciting the T mode (or HS mode) and a circuit means for generating an excitation output having a phase substantially 90 ° different from the excitation output of the T mode (or HS mode). 5. The vibratory gyroscope according to claim 1, wherein said HS mode (or T mode) is driven by an excitation output. The detection circuit means includes the first detection circuit means and the second detection circuit means utilizing an HA mode generated by different angular velocities ωx and ωz, and the first detection circuit means and the second detection circuit means 6. The vibratory gyroscope according to claim 1, wherein said detecting circuit means separates and detects ωx and ωz by performing synchronous detection having a phase shift of 90 ° from each other. 7. The vibratory gyroscope according to claim 1, wherein the piezoelectric material of the vibrator is quartz.

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