Pendulous accelerometer with balanced gas damping
First Claim
1. A pendulous accelerometer comprising:
- a) a substrate having a substantially planar upper surface;
b) a sensing plate having a central anchor portion supported on the upper surface of the substrate to define a hinge axis, the sensing plate including a solid proof mass on a first side of the central anchor portion and a substantially hollow proof mass on a second side of the central anchor portion, the solid proof mass having a first lower surface with a first electrode element thereon, and the substantially hollow proof mass having a second lower surface with a second electrode element thereon, wherein the sensing plate is mounted to rotate about the hinge axis relative to the upper surface of the substrate in response to an acceleration of the proof masses;
c) a first electrode section positioned on the upper surface of the substrate beneath the solid proof mass to interact with the electrode element on the lower surface of the solid proof mass; and
d) a second electrode section positioned on the upper surface of the substrate beneath the hollow proof mass to interact with the electrode element on the lower surface of the hollow proof mass.
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Accused Products
Abstract
A pendulous capacitive accelerometer including a substrate having a substantially planar upper surface with an electrode section, and a sensing plate having a central anchor portion supported on the upper surface of the substrate to define a hinge axis. The sensing plate includes a solid proof mass on a first side of the central anchor portion and a substantially hollow proof mass on a second side of the central anchor portion, providing for reduced overall chip size and balanced gas damping. The solid proof mass has a first lower surface with a first electrode element thereon, and the substantially hollow proof mass has a second lower surface with a second electrode element thereon. Both the solid proof mass and the hollow proof mass have the same capacitive sensing area. The sensing plate rotates about the hinge axis relative to the upper surface of the substrate in response to an acceleration.
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Citations
18 Claims
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1. A pendulous accelerometer comprising:
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a) a substrate having a substantially planar upper surface; b) a sensing plate having a central anchor portion supported on the upper surface of the substrate to define a hinge axis, the sensing plate including a solid proof mass on a first side of the central anchor portion and a substantially hollow proof mass on a second side of the central anchor portion, the solid proof mass having a first lower surface with a first electrode element thereon, and the substantially hollow proof mass having a second lower surface with a second electrode element thereon, wherein the sensing plate is mounted to rotate about the hinge axis relative to the upper surface of the substrate in response to an acceleration of the proof masses; c) a first electrode section positioned on the upper surface of the substrate beneath the solid proof mass to interact with the electrode element on the lower surface of the solid proof mass; and d) a second electrode section positioned on the upper surface of the substrate beneath the hollow proof mass to interact with the electrode element on the lower surface of the hollow proof mass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A pendulous accelerometer for operating in an open-loop mode, the accelerometer comprising:
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a) a substrate having a substantially planar upper surface; b) a sensing plate having a central anchor portion supported on the upper surface of the substrate to define a hinge axis, the sensing plate defining a solid proof mass on a first side of the central anchor portion and a substantially hollow proof mass on a second side of the central anchor portion, the solid proof mass having a first lower surface with a first electrode element thereon, and the substantially hollow proof mass having a second lower surface with a second electrode element thereon, wherein the sensing plate is mounted to rotate about the hinge axis relative to the upper surface of the substrate in response to an acceleration of the proof masses; c) a first electrode section positioned on the upper surface of the substrate beneath the solid proof mass to interact with the electrode element on the lower surface of the solid proof mass; and d) a second electrode section positioned on the upper surface of the substrate beneath the hollow proof mass to interact with the electrode element on the lower surface of the hollow proof mass, e) wherein the sensing plate is displaced from a reference position, the sensing plate being substantially parallel to the substrate in the reference position, and f) wherein a differential capacitive output signal is produced that is proportional to the magnitude of the displacement of the sensing plate from the reference position. - View Dependent Claims (17)
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18. A pendulous accelerometer for operating in a closed-loop mode, the accelerometer comprising:
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a) a substrate having a substantially planar upper surface; b) a sensing plate having a central anchor portion supported on the upper surface of the substrate to define a hinge axis, the sensing plate defining a solid proof mass on a first side of the central anchor portion and a substantially hollow proof mass on a second side of the central anchor portion, the solid proof mass having a first lower surface with a first electrode element thereon, and the substantially hollow proof mass having a second lower surface with a second electrode element thereon, wherein the sensing plate is mounted to rotate about the hinge axis relative to the upper surface of the substrate in response to an acceleration of the proof masses; c) a first electrode section positioned on the upper surface of the substrate beneath the solid proof mass to interact with the electrode element on the lower surface of the solid proof mass, wherein the first electrode section comprises a first sensing electrode and a first feedback electrode; and d) a second electrode section positioned on the upper surface of the substrate beneath the hollow proof mass to interact with the electrode element on the lower surface of the hollow proof mass wherein the second electrode section comprises a second sensing electrode and a second feedback electrode, e) wherein the first and second feedback electrodes electrostatically balance the sensing plate to maintain the sensing plate in a reference position that is substantially parallel to the upper surface of the substrate, and f) wherein an electronic output signal is produced that is proportional to a force exerted by the feedback electrodes to maintain the sensing plate in the reference position.
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Specification