Angular velocity sensor
First Claim
1. An angular velocity sensor comprising:
- a flat plate-like diaphragm including a central portion and an outer peripheral portion;
a weight disposed at the central portion of the diaphragm;
a support portion configured to support the outer peripheral portion of the diaphragm;
a vibration exciting portion operable to excite vibration having a motion component oriented in a predetermined axis of vibration with respect to the weight; and
a displacement detecting portion operable to detect displacement of the weight caused based on a Coriolis force in a direction of axis of displacement, wherein;
defining a XYZ three-dimensional orthogonal coordinate system such that an origin is located at a center position of the diaphragm and a surface of the diaphragm is included in an XY plane, one of the X and Z axes is the axis of vibration and the other is the axis of displacement, and an angular velocity around the Y axis is detected based on a detection value detected by the displacement detecting portion;
the weight is columnar or conic in shape;
the diaphragm, the weight, and the support portion are unitarily formed;
the diaphragm has such an outline shape that an outline shape of the outer peripheral portion has a straight portion or a curved portion located at each of four corner portions of a quadrangle; and
,the angular velocity sensor further comprises;
an underlying electrode formed on the surface of the diaphragm;
a piezoelectric film formed on the underlying electrode;
four vibration exciting electrodes formed on the piezoelectric film to define the vibration exciting portion; and
four angular velocity sensing electrodes formed on the piezoelectric film to be located inwardly of the four vibration exciting electrodes and to define the displacement detecting portion, wherein;
assuming a first imaginary line as being orthogonal to two opposed sides of the diaphragm and dividing the two opposed sides in half, a second imaginary line as being orthogonal to two remaining opposed sides of the diaphragm and dividing the two remaining opposed sides in half, a first imaginary diagonal line as passing through the center of two opposed corner portions of the diaphragm and a second imaginary diagonal line as passing through the center of two remaining opposed corner portions, the outline shape of the outer peripheral portion of the diaphragm is axisymmetric with respect to the first or second imaginary line;
the four vibration exciting electrodes are respectively located in four regions partitioned by the first and second imaginary lines, or in four regions partitioned by the first and second imaginary diagonal lines;
the four angular velocity sensing electrodes are respectively located in four regions partitioned by the first and second imaginary lines, or in four regions partitioned by the first and second imaginary diagonal lines;
the outline shape of each of the four vibration exciting electrodes has curved corner portions; and
the outline shape of each of the four angular velocity sensing electrodes has curved corner portions.
1 Assignment
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Accused Products
Abstract
Provided herein is a vibration-type angular velocity sensor capable of improving detection precision of angular velocities around the Z axis and preventing detection precision of angular velocities around the X and Y axes from deteriorating. A weight 3 is columnar or conic. The outline of an outer peripheral portion of a diaphragm 1 has such shape that a straight portion ST is formed at each of four corner portions of a square. Four vibration exciting electrodes 11 are respectively located in four regions partitioned by a first imaginary line L1 and a second imaginary line L2. Four angular velocity sensing electrodes 13 are respectively located in four regions partitioned by a first imaginary diagonal line CL1 and a second imaginary diagonal line Cl2.
23 Citations
12 Claims
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1. An angular velocity sensor comprising:
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a flat plate-like diaphragm including a central portion and an outer peripheral portion; a weight disposed at the central portion of the diaphragm; a support portion configured to support the outer peripheral portion of the diaphragm; a vibration exciting portion operable to excite vibration having a motion component oriented in a predetermined axis of vibration with respect to the weight; and a displacement detecting portion operable to detect displacement of the weight caused based on a Coriolis force in a direction of axis of displacement, wherein; defining a XYZ three-dimensional orthogonal coordinate system such that an origin is located at a center position of the diaphragm and a surface of the diaphragm is included in an XY plane, one of the X and Z axes is the axis of vibration and the other is the axis of displacement, and an angular velocity around the Y axis is detected based on a detection value detected by the displacement detecting portion; the weight is columnar or conic in shape; the diaphragm, the weight, and the support portion are unitarily formed; the diaphragm has such an outline shape that an outline shape of the outer peripheral portion has a straight portion or a curved portion located at each of four corner portions of a quadrangle; and
,the angular velocity sensor further comprises; an underlying electrode formed on the surface of the diaphragm; a piezoelectric film formed on the underlying electrode; four vibration exciting electrodes formed on the piezoelectric film to define the vibration exciting portion; and four angular velocity sensing electrodes formed on the piezoelectric film to be located inwardly of the four vibration exciting electrodes and to define the displacement detecting portion, wherein; assuming a first imaginary line as being orthogonal to two opposed sides of the diaphragm and dividing the two opposed sides in half, a second imaginary line as being orthogonal to two remaining opposed sides of the diaphragm and dividing the two remaining opposed sides in half, a first imaginary diagonal line as passing through the center of two opposed corner portions of the diaphragm and a second imaginary diagonal line as passing through the center of two remaining opposed corner portions, the outline shape of the outer peripheral portion of the diaphragm is axisymmetric with respect to the first or second imaginary line; the four vibration exciting electrodes are respectively located in four regions partitioned by the first and second imaginary lines, or in four regions partitioned by the first and second imaginary diagonal lines; the four angular velocity sensing electrodes are respectively located in four regions partitioned by the first and second imaginary lines, or in four regions partitioned by the first and second imaginary diagonal lines; the outline shape of each of the four vibration exciting electrodes has curved corner portions; and the outline shape of each of the four angular velocity sensing electrodes has curved corner portions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification