Teeter Totter Accelerometer with Unbalanced Mass
AssigneeAnalog Devices, Inc.
InventorJianglong Zhang
Life of this patent
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Abstract
A balanced teeter-totter accelerometer has a mass suspended above a substrate, the mass having an axis of rotation that is parallel to the substrate and substantially geometrically centered with respect to the shape of the mass. A physical acceleration in a direction perpendicular to the substrate causes the mass to rotate about the axis of rotation. The rotation is sensed by measuring a change in capacitance of electrodes on the substrate. The accelerometer may be calibrated using the same sensing electrodes.
Claims20
A microelectromechanical accelerometer comprising:
- a substrate having a top surface;
- a mass suspended above the substrate, the suspended mass having a top surface facing away from the top surface of the substrate and a bottom surface facing toward the top surface of the substrate and having first and second lateral ends, the suspended mass being adapted to rotate about an axis that is substantially geometrically centered between the first and second lateral ends, the suspended mass comprising a first section between the axis and the first lateral end and a second section between the axis and the second lateral end, the first section having a greater weight than the second section;
- a first readout electrode attached to the top surface of the substrate facing the bottom surface of the first lateral end of the suspended mass;
- and
- a second readout electrode attached to the top surface of the substrate facing the bottom surface of the second lateral end of the suspended mass.
A method of using a microelectromechanical accelerometer having a mass suspended above a substrate, the mass able to rotate about an axis of rotation, the accelerometer having a first substrate electrode capacitively coupled to a first section of the mass on a first side of the axis of rotation, and a second substrate electrode capacitively coupled to a second section of the mass on a second side of the axis of rotation, the method comprising:
- determining an offset by applying an electrical potential to the first and second electrodes;
- compensating for the offset by applying an electrical potential to one or both of the first and second electrodes;
- sensing a physical acceleration of the accelerometer by measuring an electrical capacitance of the suspended mass;
- and
- producing an output voltage that is a linear function of the measured electrical capacitance;
- wherein the axis of rotation is substantially geometrically centered between the first and second sections of the mass.
A MEMS accelerometer comprising:
- a substrate having first and second electrodes;
- a mass forming a first variable capacitance with the first electrode and a second variable capacitance with the second electrode, the mass having first and second ends;
- and
- a spring connecting the mass at a point on the mass that is substantially equidistant between the first and second ends of the mass, the spring being connected to the substrate,
- the mass having a center of mass spaced a first distance from the first end, the center of mass being spaced a second distance from the second end, the first and second distances being different.
Dependencies are inferred from the claim text.