Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Reexamination Certificate
1998-10-05
2001-02-13
Kwok, Helen C. (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
C073S504160
Reexamination Certificate
active
06186003
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a vibratory gyroscope and a vibrator capable of being preferably used in this vibratory gyroscope.
2. Related Arts
Japanese laid-open publication Tokkaihei No. 7-83671 has disclosed a vibratory gyroscope using a tuning-fork vibrator made by joining a total of three vibration pieces composed of a middle driving vibration piece and two detecting vibration pieces, being at both sides of the middle driving vibration piece all joined to a base part in one body.
FIG. 1
shows the composition of an example of such a vibratory gyroscope. In the example shown in
FIG. 1
, a tuning-fork vibrator
71
forming a vibratory gyroscope is composed of three vibration pieces which are composed of a middle driving vibration piece
73
and two detecting vibration pieces
72
and
74
arranged at both sides of it nearly in parallel with it, and a base part
75
with which the driving vibration piece
73
and the detecting vibration pieces
72
and
74
are joined in one body.
In the above-mentioned tuning-fork vibrator
71
, the driving vibration piece
73
is vibrated in the X-Z plane by an unillustrated driving means provided on the driving vibration piece
73
. And the left and right detecting vibration pieces
72
and
74
are resonated in the same X-Z plane. When a turning angular rate (&ohgr;) acts around the axis of symmetry Z of the tuning-fork vibrator
71
, a Coriolis force (f) acts on each of the detecting vibration pieces
72
and
74
. Since the detecting vibration pieces
72
and
74
are vibrating in the X-Z plane, vibration in the Y-Z plane is induced in the detecting vibration pieces
72
and
74
. A turning angular rate is measured by detecting this vibration by means of an unillustrated detecting means provided on each of the detecting vibration pieces
72
and
74
.
In a former vibratory gyroscope of the above-mentioned composition, in case of forming the vibratory gyroscope by supporting the tuning-fork vibrator
71
, the vibrator
71
is supported by fixing the entire end part
76
of the base part
75
of the tuning-fork vibrator
71
opposite to the other end part at which the driving vibration piece
73
and the detecting vibration pieces
72
and
74
exist, or by fixing an unillustrated supporting vibration piece at a position of this end part
76
corresponding to the axis of symmetry Z. Therefore, it cannot be said that a Coriolis force generated by a turning angular rate is efficiently utilized for action of a detecting vibration in the detecting vibration pieces
72
and
74
, and there is a problem that the sharpness of resonance (Q value) of the detecting vibration in the Y-Z plane in the detecting vibration pieces
72
and
74
is low and the measurement sensitivity for a turning angular rate is low.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a vibratory gyroscope which can improve the sharpness of resonance (Q value) of a detecting vibration in a detecting vibration piece and can measure a turning angular rate with high sensitivity.
Another object of the invention is to provide an analyzing method for manufacturing a vibrator having a high sharpness of resonance of a detecting vibration in a detecting vibration piece, and a supporting method and a manufacturing method using this analyzing method.
A vibratory gyroscope of the present invention is a vibratory gyroscope for detecting a turning angular rate of rotation applied to a vibrator, which vibratory gyroscope a vibrator provided with a plurality of vibration pieces and a base part having the plurality of vibration pieces connected with it and is composed so as to obtain the turning angular rate on the basis of a detecting vibration excited in the vibrator according to the turning angular rate when giving a driving vibration to at least one of the vibration pieces, and supports the vibrator in a domain where the detecting vibration is smallest in the vibrator, said domain being in the vicinity of the center of gravity of the vibrator.
Preferably the vibrator is provided with a supporting hole in a domain where the detecting vibration is smallest in a state where the supporting hole is not provided in the vibrator and the vibrator is supported with or in the vicinity, preferably on or near the inner wall face of this supporting hole.
Supporting the vibrator in the vicinity of the supporting hole means supporting the surface of the vibrator within a range of 1 mm from the periphery of the supporting hole.
Another embodiment of the present invention is a vibratory gyroscope for detecting a turning angular rate of rotation applied to a vibrator and the vibrator is provided with a plurality of vibration pieces and a base part having the plurality of vibrating pieces connected with it and the base part is provided with a supporting hole. The gyroscope is composed so as to obtain the turning angular rate on the basis of a detecting vibration excited in the vibrator according to the turning angular rate when giving a driving vibration to at least one of the vibration pieces. The gyroscope is provided with a supporting means for supporting the vibrator with or in the vicinity of the supporting hole.
And the present invention is a vibrator formed out of a piezoelectric single crystal and comprises a plurality of vibration pieces each of which performs a bending-vibration and a base part having the plurality of vibration pieces connected with it and said base part is provided with a supporting hole for supporting said vibrator.
Another embodiment vibratory gyroscope of the present invention is a for detecting a turning angular rate of rotation applied to a vibrator, wherein the vibrator is provided with a plurality of vibration pieces and a base part having the plurality of vibration pieces connected with it and is composed so as to obtain the turning angular rate on the basis of a detecting vibration excited in the vibrator according to the turning angular rate when giving a driving vibration to at least one of the vibration pieces, and the vibrator is supported in a domain where the detecting vibration is smallest in the vibrator, said domain being in the vicinity of the center of gravity of the vibrator (when it is not vibrated). As a result it is possible to improve the sharpness of resonance (Q value) of a detecting vibration in a detecting vibration piece, raise the sensitivity, and reduce the influence which the strain of a vibrator, caused by vibration or acceleration given from the outside of the vibrator, exerts on its vibrating state.
And as a preferred embodiment, to support a vibrator at a domain where a domain where a detecting vibration is smallest and a domain where a driving vibration is smallest overlap each other can raise the Q value of the driving vibration as well as the detecting vibration and further improve the sensitivity.
In a particularly preferred embodiment, a driving vibration and the detecting vibration occur in the plane of a vibrator.
Since the amplitude of a driving vibration is considerably larger than the amplitude of a detecting vibration, it is important to reduce the influence of the driving vibration on the detecting vibration. In a preferred embodiment, a vibrator is supported at or in the vicinity of the center of gravity of the vibrator. Thanks to this, it is possible to minimize the influence of the driving vibration on the detecting vibration.
That a vibrator is supported at or in the vicinity of the center of gravity GO of the vibrator or the center of gravity GD of the driving vibration means that a vibrator supporting point may be located substantially at the center of gravity GO or GD and is within a circle of 1 mm in diameter, said circle having the center of gravity GO or GD as its center.
In a preferred embodiment, a supporting means is joined onto the surface of a vibrator in a domain where the detecting vibration is is smallest by adhesion, gluing, soldering, metalizing or the like, or by pressure-joining.
And it is preferable to provide a supporting hole
Gouji Shosaku
Kikuchi Takayuki
Osugi Yukihisa
Soma Takao
Kwok Helen C.
NGK Insulators Ltd.
Wall Marjama Bilinski & Burr
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