437 results about "Proof mass" patented technology

A method and apparatus are described for fabricating a high aspect ratio MEMS device by using metal thermocompression bonding to assemble a reference wafer (100), a bulk MEMS active wafer (200), and a cap wafer (300) to provide a proof mass (200d) formed from the active wafer with bottom and top capacitive sensing electrodes (115, 315) which are hermetically sealed from the ambient environment by sealing ring structures (112 / 202 / 200a / 212 / 312 and 116 / 206 / 200e / 216 / 316).

A highly sensitive silicon micro-machined sensor package is provided for use in a micro-g environment that can also resist high shock in excess of 5000 g. The sensor is provided to measure acceleration in cooperation with associated electronics which are required to have electrical contact with sensor elements. The sensor is sealed in a high vacuum environment, and is arranged and designed to be free of temperature induced stress to the sensor. The sensor die package assembly comprises a silicon micro-machined sensor die, a ceramic package, two contact springs, a shorting clip, solder preform, a metal lid and a getter foil for ensuring a good vacuum for an extended period. The sensor die comprises a moving mass with eight supporting flexures on both sides of the proof mass. The proof mass's movement is protected on both sides by a top and a bottom cap. Acceleration applied to the package and the die causes the proof mass to move vertically in relation with the adjacent caps. The changes in distance between the proof mass and the caps in turn generate a change in an electrical signal which corresponds to the capacitance changes between the gaps. The sensor die package arrangement provides that the sensor die be secured within an evacuated ceramic case. Electrical connections made between external contacts of the case and contacts of the sensor die within the case are made through conductive springs, thereby minimizing materials in the interior of the case which would outgass in the vacuum environment.

A micromachined inertial sensor with a single proof-mass for measuring 6-degree-of-motions. The single proof-mass includes a frame, an x-axis proof mass section attached to the frame by a first flexure, and a y-axis proof mass section attached to the frame by a second flexure. The single proof-mass is formed in a micromachined structural layer and is adapted to measure angular rates about three axes with a single drive motion and linear accelerations about the three axes.

A system and method in accordance with the present invention provides for a low cost, bulk micromachined accelerometer integrated with electronics. The accelerometer can also be integrated with rate sensors that operate in a vacuum environment. The quality factor of the resonances is suppressed by adding dampers. Acceleration sensing in each axis is achieved by separate structures where the motion of the proof mass affects the value of sense capacitors differentially. Two structures are used per axis to enable full bridge measurements to further reduce the mechanical noise, immunity to power supply changes and cross axis coupling. To reduce the sensitivity to packaging and temperature changes, each mechanical structure is anchored to a single anchor pillar bonded to the top cover.

A portable medical device is provided with an internal accelerometer device. The medical device includes a circuit board, the accelerometer device, and a response module coupled to the accelerometer device. The accelerometer device is mechanically and electrically coupled to the circuit board, and it includes a plurality of mass-supporting arms for a plurality of electrically distinct sensor electrodes, piezoelectric material for the mass-supporting arm, and a proof mass supported by the mass-supporting arms. Each of the mass-supporting arms has one of the sensor electrodes located thereon. Acceleration of the proof mass causes deflection of the piezoelectric material, which generates respective sensor signals at one or more of the sensor electrodes. The response module is configured to initiate an acceleration-dependent operation of the portable medical device in response to generated sensor signals present at the sensor electrodes.

A solid state silicon micromachined acceleration and Coriolis (MAC) sensor that measures linear and angular motion. The MAC sensor is a single device that performs the functions of a conventional accelerometer and a gyroscope simultaneously. The MAC sensor is unique in that it is a differential dual stage device using only one micromachined proof mass to measure both linear and angular motions. The single proof mass is connected to opposing electromechanical resonators in a monolithic microstructure made from single crystal silicon. This unique design offers improvements in measurement performance and reductions in fabrication complexity that are beyond the state the art of earlier micromachined inertial sensors.

A sensor that measures angular velocity about an axis that is normal to a sensing plane of the sensor. The sensor comprises a sensing subassembly that includes a planar frame parallel to the sensing plane, a first proof mass disposed in the sensing plane, a second proof mass disposed in the sensing plane laterally to the first proof mass, and a linkage within the frame and connected to the frame. The linkage is connected to the first proof mass and to the second proof mass. The sensor further includes actuator for driving the first proof mass and the second proof mass into oscillation along a drive axis in the sensing plane. The sensor further includes a first transducer to sense motion of the frame in response to a Coriolis force acting on the oscillating first proof mass and the oscillating second proof mass.

A system and method for inputting motion measurement data into a computationally based device are provided. In a first version three-axis accelerometer determines components of an inertial force vector with respect to an orthogonal coordinate system. The accelerometer includes a sensor die made of a semiconductor substrate having a frame element, a proof mass element, and an elastic element mechanically coupling the frame and the proof mass. The accelerometer also has three or more stress-sensitive IC components integrated into the elastic element adjacent to the frame element for electrical connectivity without metal conductor traversal of the elastic element.

A transducer is provided herein which comprises an unbalanced proof mass (51), and which is adapted to sense acceleration in at least two mutually orthogonal directions. The proof mass (51) has first (65) and second (67) opposing sides that are of unequal mass.

A multi-axis accelerometer is consisted of a substrate with sensing electrodes and a structure layer. The structure layer includes anchor bases fixed on the substrate. A first proof mass is disposed over the substrate and has a first opening and a second opening symmetric to each other. The first proof mass is suspended to the anchor bases. Fixed sensing blocks are disposed on the substrate, and capacitors are formed between each fixed sensing block and the first proof mass for sensing acceleration along two in-plane directions. A second proof mass and a third proof mass are disposed in the first opening and the second opening and are asymmetrically suspended. Separate electrodes are disposed on the substrate and form two differential capacitors with the second proof mass and the third proof mass for sensing the out-of-plane acceleration.

Micromachined accelerometer having one or more proof masses (16, 36, 37, 71, 72) mounted on one or more decoupling frames (17, 38, 39) or on a shuttle (73) such that the proof mass(es) can move along a first (y) axis in response to acceleration along the first axis while being constrained against movement along a second (x) axis and for torsional movement about a third (z) axis perpendicular to the first and second axes in response to acceleration along the second axis. Electrodes (26, 53, 54, 78, 79) that move with the proof mass(es) are interleaved with stationary electrodes (27, 56, 57, 81, 82) to form capacitors (A-D) that change in capacitance both in response to movement of the proof mass(es) along the first axis and in response to torsional movement of the proof mass(es) about the third axis, and circuitry (31-34) connected to the electrodes for providing output signals corresponding to acceleration along the first and second axes. The capacitances of two capacitors on each side of the second axis change in the same direction in response to acceleration along the first axis and in opposite directions in response to acceleration along the second axis. Signals from the capacitors that change capacitance in opposite directions both in response to acceleration along the first axis and in response to acceleration along the second axis are differentially combined to provide first and second difference signals, and the difference signals are additively and differentially combined to provide output signals corresponding to acceleration along the first and second axes.

This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for making and using gyroscopes. Such gyroscopes may include a sense frame, a proof mass disposed outside the sense frame, a pair of anchors and a plurality of drive beams. The plurality of drive beams may be disposed on opposing sides of the sense frame and between the pair of anchors. The drive beams may connect the sense frame to the proof mass. The drive beams may be configured to cause torsional oscillations of the proof mass substantially in a first plane of the drive beams. The sense frame may be substantially decoupled from the drive motions of the proof mass. Such devices may be included in a mobile device, such as a mobile display device.

A sensor that measures angular velocity about an axis that is normal to a sensing plane of the sensor. The sensor comprises a sensing subassembly that includes a planar frame parallel to the sensing plane, a first proof mass disposed in the sensing plane, a second proof mass disposed in the sensing plane laterally to the first proof mass, and a linkage within the frame and connected to the frame. The linkage is connected to the first proof mass and to the second proof mass. The sensor further includes actuator for driving the first proof mass and the second proof mass into oscillation along a drive axis in the sensing plane. The sensor further includes a first transducer to sense motion of the frame in response to a Coriolis force acting on the oscillating first proof mass and the oscillating second proof mass.

A system and method in accordance with the present invention provides for a low cost, bulk micromachined accelerometer integrated with electronics. The accelerometer can also be integrated with rate sensors that operate in a vacuum environment. The quality factor of the resonances is suppressed by adding dampers. Acceleration sensing in each axis is achieved by separate structures where the motion of the proof mass affects the value of sense capacitors differentially. Two structures are used per axis to enable full bridge measurements to further reduce the mechanical noise, immunity to power supply changes and cross axis coupling. To reduce the sensitivity to packaging and temperature changes, each mechanical structure is anchored to a single anchor pillar bonded to the top cover.

The invention relates to accelerometer structures micro-machined according to micro-electronics technologies. The accelerometer according to the invention comprises a substrate, an elastically deformable thin-layer membrane suspended above the substrate and secured to the substrate at its periphery, a proof mass suspended above the membrane and linked to the latter by a central stud, and capacitive interdigitated combs distributed about the mass, having movable plates secured to the mass and fixed plates secured to the substrate. The fixed plates and movable plates of the various combs are of differentiated heights to help in the discrimination of the upward and downward vertical accelerations.

A process for fabricating a pendulous accelerometer, including the steps of: providing a first substrate having a top planar surface, etching a portion of the first substrate to a first predetermined depth from the top planar surface to form a plurality of first protrusions, providing a second substrate, etching a portion of the second substrate to a second predetermined depth to form a plurality of second protrusions, bonding planar surfaces of the first protrusions to planar surfaces of the second protrusions, and etching a portion of the first substrate from an opposite side of the first substrate to a third predetermined depth equal to or greater than the difference between the total thickness of the first substrate and the first predetermined depth to form a freely rotatable sensing plate that includes a substantially hollow proof mass.

Methods and apparatus are provided for detecting a rate of rotation. In one implementation, the method includes vibrating a proof mass at a pre-determined frequency in a drive axis. In response to a rotation, sensing an amount of deflection of the proof mass in an axis orthogonal to the drive axis, in which the amount of deflection is sensed as a change in charge. The method further includes generating a quadrature error cancellation signal to substantially cancel quadrature error from the sensed change in charge.

An apparatus and method for force sensing device having a pendulous mechanism proof mass formed in a silicon semiconductor substrate and structured for rotation about an intermediate rotational axis, the proof mass being substantially rectangular in shape with opposing first and second lateral peripheral edges and opposing first and second endwise peripheral edges. A plurality of capacitor comb teeth are formed symmetrically along the opposing first and second endwise peripheral proof mass edges and along the opposing first and second lateral peripheral proof mass edges adjacent to the first and second endwise peripheral edges, and one or more mass reduction apertures are formed in an interior portion of the proof mass on one side of the intermediate hinge axis.

A method for reducing undesired movements of proof masses in micro-electromechanical systems (MEMS) devices is described where the proof masses are suspended above a substrate by one or more suspensions. The method includes providing an anchor on the substrate substantially between a first proof and suspensions for the first proof mass and a second proof mass and suspensions for the second proof mass, coupling a first portion of a beam to the first proof mass, coupling a second portion of the beam to the second proof mass, and attaching a third portion of the beam to the anchor, the third portion extending between the first portion and second portion of the beam, the anchor and the third portion configured to allow for rotation about an axis perpendicular to the substrate.