Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Reexamination Certificate
1999-12-30
2001-12-11
Kwok, Helen (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
C073S504140
Reexamination Certificate
active
06327907
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a microgyroscope of a microstructure, in which a voltage supplied to the exciting comb drivers of an outer frame is easily offset, and the exciting comb drivers are stably resonated without being influenced by an exciting voltage. Particularly, the present invention relates to a microgyroscope of a microstructure, in which sensing direction beam elastic bodies are provided within the outer frame to install an inner frame, further comb sensors with combs arranged horizontally are asymmetrically installed at both sides of the outer frame, and exciting direction elastic bodies are installed at four corners of the outer frame so as to separate the oscillations under the exciting and sensing modes, so that the voltage supplied to the exciting comb drivers of the outer frame can be easily damped through comb sensing parts of the both sides, thereby ensuring stable resonances of the microgyroscope without being influenced by the exciting voltage.
BACKGROUND OF THE INVENTION
Generally, the angular velocity sensing devices for detecting the angular velocities of inertial bodies have been widely employed as a component of navigation apparatus in the ocean vessels, air planes and the like. At the present, this device has been extended to the navigation apparatus of automobiles, and to the high performance video cameras as a hand-oscillation compensating device.
The conventional gyroscope which has been used for military purposes and for air planes is manufactured by using a plurality of high precision components and through a complicated assembling process, and therefore, a precise performance is possible. However, its manufacturing cost is high, and its bulk is very large, with the result that it cannot be used for the general industries, and for the home power appliances.
Recently, a small gyroscope has been developed by attaching a piezoelectric device to a triangular prism beam, and this is used as a hand-oscillation sensor for a small video camera. Further, in order to overcome the difficulties of the gyroscope having the piezoelectric device, a small gyroscope with an improved cylindrical beam structure has been developed.
However, these two kinds of the small gyroscopes require precisely machined components, and therefore, the manufacture becomes difficult, while the manufacturing cost becomes high. Further, the mentioned two kinds of gyroscope includes a plurality of mechanical components, and therefore, it is difficult to form a circuit integration.
The principle of the gyroscope is as follows. That is, when a rotating inertial body which rotates or oscillates in a first axis direction receives an input of an angular velocity in a second axis direction (which is perpendicular to the first axis direction), the gyroscope detects a Coriolis force which acts in a third axis direction (which is rectangular to the first and second axes direction).
Under this condition, if the forces acting on the inertial body are made to be balanced, then the detection of the angular velocity has to be more precise. Particularly, if the linearity and the band width are to be expanded, a force balancing structure is required.
A conventional microgyroscope related to this technique is illustrated in FIG.
1
.
As shown in
FIG. 1
, the microgyroscope includes: a plurality of combs
20
installed within a frame
10
in the lateral direction and in the sensing direction (y axis direction); a plurality of sensing direction (y axis direction) sensing electrodes
40
interposed between the combs
20
, the electrodes
40
being supported by positive and negative electrode supporting parts
30
and
30
′; sensing direction elastic bodies
50
installed at four places (the top and bottom and left and right) of the frame
10
; oscillation structures
60
installed on the sensing direction elastic bodies
50
in the exciting direction (x axis); comb drivers
70
for causing oscillations on the oscillation structures
60
by supplying voltages; and exciting direction elastic bodies
80
disposed at the four corners of the oscillations structure.
In the conventional microgyroscope constituted as described above, the oscillation structures
60
are oscillated in the exciting direction (x axis) by receiving an ac voltage from the exciting drivers
70
. When the oscillation structures
60
are oscillated, if an angular velocity input is received in a direction (y axis) perpendicular to the plane of the gyroscope, then a Coriolis force is generated in the sensing direction, with the result that the internal structures of the frame
10
are moved in the sensing direction. This movement causes a variation of the capacitance between the sensing electrodes
40
and the combs
20
. Thus the amount of the angular velocity can be calculated by measuring the varied capacitance.
In the above described case, the oscillations caused by the influence of the oscillation structures
60
and the internal structures of the frame
10
can be reduced by separating the elastic exciting bodies
80
and the sensing direction elastic bodies
50
of the frame
10
of the gyroscope from each other by making them symmetric. However, there is a problem as described below. That is, the upper and lower portions of the oscillation structures
60
are installed on the sensing direction elastic bodies
50
, and therefore, the upper portion and the lower portion of the oscillation structures make unstable movements up and down respectively.
Particularly, if the oscillation structures
60
and the frame
10
are to make stable oscillations in the exciting direction (x axis), there is required an element for sensing the oscillations of the oscillation structures. The oscillation signals which are detected by the oscillation sensing element supply certain exciting signals through a control circuit (which includes an external sensing circuit and an amplifying circuit) to the comb drivers
70
. The oscillation structures
60
and the frame
10
perform stable oscillations at a resonance frequency which is decided by the mass of the oscillation structures
60
, and the mass of the frame
10
, and by the value of the exciting direction elastic bodies.
FIGS. 2A and 2B
are graphical illustrations showing the ac signal interference by the exciting voltage supplied to both sides of the exciting comb drivers
70
. As shown in these drawings, a negative interference effect is invited to the oscillation signals of the oscillation detecting element. Accordingly, stable oscillations become impossible.
SUMMARY OF THE INVENTION
The present invention is intended to overcome the above described disadvantages of the conventional techniques.
Therefore it is an object of the present invention to provide a microgyroscope in which an interference effect by a voltage supplied to the exciting comb drivers of an outer frame are easily damped by asymmetric comb sensors, thus the microgyroscope is stably resonated without being influenced by the magnitude of the exciting voltage, thus the microgyroscope can be magnetically oscillated even under a vacuum with a large air resistance, thus the resolving power and the sensitivity of the gyroscope are maximized, and thus the life expectancy of the gyroscope can be extended.
In achieving the above object, the microgyroscope according to the present invention includes: an inner frame excitingly installed within an outer frame; a plurality of combs installed laterally and in a sensing direction (y axis) at both sides of the inner frame; sensing direction sensing electrodes disposed between the plurality of the combs at certain intervals, and supported by upper and lower electrode supporting parts; elastic beam bodies installed between the inner and outer frames excitingly in the sensing direction; comb sensors installed asymmetrically at both sides of the outer frame in a horizontal direction; elastic bodies installed at four corners of the outer frame excitingly in an exciting direction (x axis); and exciting drivers installed above and below of the outer frame, for causing
Kwok Helen
Lowe Hauptman & Gilman & Berner LLP
Samsung Electro-Mechanics Co. Ltd.
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