Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Patent
1997-11-21
2000-05-23
Williams, Hezron
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
G01C 1900
Patent
active
060653396
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration gyro sensor. In particular, the present invention relates to a vibration gyro sensor (scope) for detecting the angular velocity of rotation by utilizing the Coriolis force generated when a vibrator is rotated while making vibration, and a method for producing the vibration gyro sensor. The present invention also relates to a combined sensor including the vibration gyro sensor.
2. Background Art
The gyro sensor (scope), which is a sensor for detecting the angular velocity of rotation, has been hitherto used, for example, for inertial navigation systems of aircraft and shipping. Recently, the gyro sensor has been used for vehicle-carried navigation systems and for attitude control systems of automatically guided robot vehicles. Further, the gyro sensor has been used, for example, for picture blurring-preventive systems of VTR cameras. In such circumstances, a compact type gyro sensor is required, which is appropriately used in various fields as described above. Accordingly, the vibration gyro sensor attracts attention.
As well-known, the vibration gyro sensor (scope) of this type has a basic structure comprising a driving piezoelectric element and a detecting piezoelectric element which adhere to a vibrator formed of a constant resilience metal represented by the elinvar alloy. In a rectangular coordinate system of x, y, z axes, when the vibrator is rotated about the z axis while giving bending vibration in the x axis direction to the vibrator by using the driving piezoelectric element, the Coriolis force acts in the y axis direction to the vibrator. Accordingly, the bending vibration in the y axis direction caused in the vibrator by the Coriolis force is detected as a voltage by the aid of the detecting piezoelectric element. The angular velocity is determined on the basis of the detected voltage.
However, in the case of the conventional vibration gyro sensor as described above, the amount of displacement of the vibrator, which is based on the vibration induced by the driving piezoelectric element, is small. Therefore, the voltage (electromotive force), which is detected by the detecting piezoelectric element, is small. As a result, the conventional vibration gyro sensor suffers from low sensitivity.
In addition, the driving piezoelectric element and the detecting piezoelectric element are glued and fixed to the vibrator by using an adhesive. Therefore, the adhesive intervenes between the vibrator and the piezoelectric elements. As a result, the stress is absorbed by the adhesive. This is problematic since the detection sensitivity is lowered.
When the vibrator comprises a member which is composed of a sound chip or a tuning fork formed of an elinvar alloy, a problem arises in that the characteristics of the vibrator tend to be affected by an ambient magnetic field, because the elinvar alloy is a ferromagnetic material. Further, due to the shape or the material of the vibrator as described above, there is an implicit problem that it is difficult to perform processing or machining when the resonant frequency of the vibrator is adjusted.
SUMMARY OF THE INVENTION
The present invention has been made is to solve all of the problems as described above and provide a vibration gyro sensor having excellent sensitivity. Another object of the present invention is to provide a vibration gyro sensor made of ceramics, in which the characteristics of the vibrator are barely affected by an ambient magnetic field, processing or machining can be easily performed, and the electric characteristics can be advantageously adjusted.
The present invention provides a vibration gyro sensor which is constructed as a whole by an integrated fired product made of ceramics without using any magnetic material. Therefore, the vibration gyro sensor according to the present invention scarcely affected by any ambient magnetic field. Further, the vibration gyro sensor includes first plate-shaped sections and second plate-shaped sections which
REFERENCES:
patent: 2247960 (1941-07-01), Michaels
patent: 2513340 (1950-07-01), Lyman
patent: 4628734 (1986-12-01), Watson
patent: 5533397 (1996-07-01), Sugitani et al.
Namerikawa Masahiko
Ohnishi Takao
Shibata Kazuyoshi
Takeuchi Yukihisa
Moller Richard A.
NGK Insulators Ltd.
Williams Hezron
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