Measuring and testing – Speed – velocity – or acceleration – Angular rate using gyroscopic or coriolis effect
Reexamination Certificate
1999-12-10
2001-10-30
Kwok, Helen (Department: 2856)
Measuring and testing
Speed, velocity, or acceleration
Angular rate using gyroscopic or coriolis effect
C073S504080
Reexamination Certificate
active
06308567
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon Japanese Patent Application No. Hei. 10-351511 filed on Dec. 10, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to angular velocity sensors, and particularly to an angular velocity sensor (e.g., a gyro sensor, yaw rate sensor), which can detect Corioli's force that acts on a movable portion provided on a substrate along a flat plane parallel to the substrate when angular velocity is generated about an perpendicular axis of the substrate as a result of oscillation of the movable portion.
2. Related Art
Conventionally, capacitance detection type angular velocity sensors have been used for vehicles, arcade games and so on, and have been developed to further downsize so as to reduce mounting space or cost. However, output signals based on capacitance changes due to an action of the angular velocity necessarily becomes small, since a capacitance detection portion is downsized. It is difficult to design a processing circuit to accurately take out only desired signals from such small output signals with removing noise.
This kind of angular velocity sensor is disclosed in JP A 8-220125. This conventional angular velocity sensor has two oscillatory masses (oscillators) that oscillate in opposite phases each other in a frame and an evaluation unit that processes measured signals from the angular velocity sensor. The evaluation unit filters out disturbance generated by the oscillatory masses. This conventional angular velocity sensor can output signals based on substantially twice capacitance changes and can remove the noise relatively easily.
However, according to the conventional angular velocity sensor, since the oscillatory masses having rectangular-shape are merely arranged in parallel to each other, a size of total angular velocity sensor tends to become bulky. Hence, it is inadequate from a downsizing standpoint.
In this conventional angular velocity sensor, it can be thought to further add the oscillatory masses to further enlarge the measured signals from the angular velocity sensor for the purpose of improving an S/N ratio (signal
oise ratio).
However, the mere addition of the oscillatory masses may cause inconveniences that the size of total angular velocity sensor becomes further bulky, and that the noise may not be adequately removed.
SUMMARY OF THE INVENTION
This invention has been conceived in view of the background thus far described and its first object is to provide an angular velocity sensor adequate for downsizing.
Its second object is to provide a compact angular velocity sensor, which can improve an S/N ratio.
According to the present invention, an angular sensor comprises: a plurality of movable portions movably supported on the substrate, being point-symmetry arranged each other with respect to a predetermined point and being movable in circumstantial direction about the predetermined point; and a detection portion confronted with the movable portions for detecting displacement of the movable portions.
According to this structure, one of Corioli's force and external force such as external acceleration can become the same direction among the point-symmetry arranged movable portions, and another of the Corioli's force and the external force can become reverse direction among the point-symmetry arranged movable portions. Therefore, a signal due to Corioli's force can be easily taken out with easily canceling the external force.
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Teegarden et al., “How to Model and Simulate Microgyroscope Systems,” The Practical Engineer, IEEE Spectrum, Jul. 1998, pp. 66-75.
Fukada Tsuyoshi
Higuchi Hirofumi
Ohya Nobuyuki
Denso Corporation
Kwok Helen
Pillsbury & Winthrop LLP
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