Alliedsignal Inc.

Sundstrand Data Control, Inc.

Honeywell International Inc.

Sundstrand Corporation

New Sd, Inc.

James R Woodruff

Brian L Norling

Ronald B Leonardson

Michael J Robinson

Rand H Hulsing, Ii

Rex B Peters

Steven A Foote

Richard A Hanson

Gerald R Newell

Mitchell J Novack

Peter J Hesketh

David W Wine

A vibratory transducer ( ) for an accelerometer ( ) having a pair of parallel beams ( ) with first and second fixed end portions, and a pair of electrodes ( ) positioned adjacent to the beams for generating an electrostatic force to transversely vibrate the beams at a resonant frequency. The vibration frequency of the beam is generally related to axial (i.e., compression or tension) forces applied to either one of the fixed ends of the beam so that the magnitude of the force applied can be measured by changes in the vibration frequency. The electrodes and the beams each have a plurality of fingers ( ) extending laterally outward so that the beam fingers and the electrode fingers are intermeshed with each other. The intermeshed fingers reduce the transducer's sensitivity to changes in applied voltage, thereby increasing the accuracy of the frequency signal. In addition, the intermeshed fingers enable the transducer to operate effectively at pressure levels substantially above vacuum to permit gas damping of the proof mass.

Electrostatic drive for accelerometer

A pendulous accelerometer wherein the active reaction mass is pendulously mounted external to a fixed support structure and may include sensor cover of covers in the total active reaction mass.

Vibrating beam accelerometer

A mechanical resonator having interconnected vibrating beams and counter balances whereby transfer of energy from the vibrating beams is essentially eliminated.

Vibrating beam force sensor

An accelerometer formed from a semiconducting substrate and first and second active layers coupled to the opposite surfaces of the substrate. The substrate has a frame and a proof mass suspended from the frame by one or more flexures for rotation about an input axis in response to an applied force. The active layers each include a vibratory force transducer mechanically coupled to the proof mass for detecting a force applied to the proof mass. With this configuration, the transducers are located on either side of the substrate, which improves the differential design symmetry of the force detecting apparatus. This reduces the common mode non-linear response characteristics of the accelerometer, particularly in high dynamics applications, where high performance is required.

Vibrating beam accelerometer and method for manufacturing the same

The method of the present invention includes forming a frame and a proof mass suspended from the frame by one or more flexures, and including within a thin active layer one or more vibratory force transducers suitably coupled to the proof mass for detecting a force applied to the proof mass. According to the present invention, an insulating layer, such as silicon oxide, is formed between the substrate and the active layer to insulate the active layer from the substrate. Providing a separate insulating layer between the substrate and active layer improves the electrical insulation between the proof mass and the transducers, which allows for effective operation over a wide range of temperatures.

Method for manufacturing a vibrating beam accelerometer

The apparatus of the present invention includes a substrate and a thin active layer each comprising a semiconducting material. The substrate has a frame and a proof mass suspended from the frame by one or more flexures, and the active layer includes one or more vibratory force transducers suitable coupled to the proof mass for detecting a force applied to the proof mass. According to the present invention, an insulating layer, such as silicon oxide, is formed between the substrate and the active layer to insulate the active layer from the substrate. Providing a separate insulating layer between the substrate and active layer improves the electrical insulation between the proof mass and the transducers, which allows for effective operation over a wide range of temperatures. The vibratory force transducers comprise first and second parallel beams, each beam having one or more fingers extending laterally outward from the beam and intermeshed with fingers projecting laterally inward towards the beam from an electrode positioned adjacent to the beam.

Accelerometers and methods of forming accelerometers are described. The accelerometers are provided with electrically conductive structure configured for connection with external circuitry. The electrically conductive structure has a folded-back architecture which reduces temperature-induced anomalies which can adversely impact acceleration-sensing function of the accelerometer.

Vibrating beam accelerometers and methods of forming vibrating beam

A tunnel current position sensor has a first sensing electrode coupled to a compliant beam for providing force relief to the sensor. The beam is connected in fixed relationship with a first object. A second sensing electrode is coupled to a second object. The compliant beam elastically deforms to prevent damage resulting from crashing of the electrodes.

Tunnel current sensor with force relief protection

An electromagnetically-excited silicon micromachined vibrating beam accelerometer includes a proof mass or pendulum attached to an outer casing by way of a pair of flexures defining a hinge axis HA. A double-ended tuning fork (DETF) is connected between the proof mass and the casing along an axis generally perpendicular to the hinge axis (HA) defining a sensitive axis SA such that forces applied along the hinge axis HA will cause the DETF to go into either compression or tension. Electromagnetic excitation causes the vibrating beams to vibrate at a resonant frequency when the proof mass is at rest. In response to a force along the sensitive axis SA, the vibrating beams go into either tension or compression resulting in a change in the resonant frequency which, in turn, is used as a measure of the force. The excitation includes a magnetic field B, applied in a direction generally perpendicular to the plane of the DETF and perpendicular to the sensitive axis SA. In order to eliminate the effects of variations in the resistance path of the vibrating beams due to either manufacturing tolerances and temperature, the DETF in accordance with the present invention is formed as a dual-port device with separate conducting paths for the drive circuit and the pick-off circuit. By providing separate conducting paths, the effects of changes in the resistance path of the drive circuit have little effect on the overall performance of the oscillator. Since the beams are separated, the DETFs are configured to provide sufficient mechanical coupling of the beams forming the DETF.

Two-port electromagnetic drive for a double-ended tuning fork

A reactionless single beam vibrating force transducer utilizes counterbalances at opposite ends of the beam that rotate in directions opposite to the ends of the vibrating beam to reduce rotational and normal forces transmitted to the end supports for the beam. The proportions of the counterbalances relative to the size of the beam may be chosen to reduce forces in a direction normal to the beam to zero at the expense of some rotational moments at the end of the beam support, or to reduce moments at the expense of some normal force. The relative amounts of residual rotational moments and normal force can be adjusted to suit particular applications. Flexures may also be utilized to reduce the rotational moments transferred to the beam support even further.

Reactionless single beam vibrating force sensor

A method for selectively etching a semiconductor wafer in the presence of an electrochemical etchant wherein the electrical potential of the area that is selectively etched is automatically changed to a potential at which the etching is inhibited once the desired etching in the area is completed. The method is described with respect to making an electrode tip for a tunnel current sensing device.

Method of making an electrode tip for a tunnel current sensing device

A servo accelerometer uses a tunnel current sensor having a first sensing electrode coupled in fixed alignment with a frame and a second sensing electrode coupled to a proof mass. A position sensing circuit develops a sensing signal indicative of displacement of the proof mass. A feedback circuit provides an output signal and provides a feedback signal to electrostatic drive electrodes for applying an electrostatic repositioning force to the proof mass. The proof mass and frame are connected by a highly compliant suspension structure.

Servo accelerometer with tunnel current sensor and complementary

A servo accelerometer permits compliant suspension with a pair of flexures by using a plurality of tunnel current position sensors each respectively associated with a corresponding pair of electrostatic drive electrodes. The tunnel current position sensors and the electrostatic drive electrodes are positioned to control undesired movement of the proof mass about a first axis which is normal to the input axis of the accelerometer. In another embodiment, three tunnel current sensors and three pairs of drive electrodes are used to control movement of the proof mass about the first axis and a second axis.

Multiple servo loop accelerometer with tunnel current sensors

A vibrating beam force transducer is comprised of an oscillating sensing element having a frequency output indicative of the force applied to the sensing element. The sensing element has a variable electrical resistance which can vary in accordance with temperature fluctuations over the operating range of the transducer. A drive circuit is electrically coupled to the sensing element for causing the sensing element to oscillate at a resonant frequency that is a function of the force applied to the sensing element. The drive circuit includes a source of DC voltage, which is utilized for altering the electrical characteristics of the drive circuit in response to variations in the electrical resistance of the sensing element.

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Redmond, WA, United States of America

James R Woodruff