An accelerometer fabricated from a semiconductor substrate sandwiched between two non-conductive plates is shown having an inertial mass formed by etching the substrate. The mass is joined to the substrate by hinges having crossed blades to provide flexure in one direction and rigidity in other directions. The fabrication technique permits the integration of accelerometer servo and signal processing circuitry upon the same substrate in which the accelerometer mass is formed.

Integrated force balanced accelerometer

A flat web coupler (200) for use with a multi joint manually positional measuring arm of a three-dimensional coordinate measurement system, comprises a web portion (424) and flexing members (420, 421) joined by links (422, 423) to the web portion via spring portions (427), to accurately translate rotational motion between a transfer coupling and a measurement device while accommodating misalignment between the components. In addition, the flat web coupler of the present invention is relatively thin thereby minimizing the space required within the arm for its mounting as well as the weight and moment created by the coupler and transferred to the arm.

Flat web coupler for coordinate measurement systems

A flexible hinge device comprises a laminar silicon body having a groove portion etched away to define a thin flexible strip joining two rigid end portions The silicon forming the hinge is usually of a single crystal structure Break-off supports may be provided to support the structure prior to use

Flexible hinge device

L'invention concerne un transducteur compensant une deflexion due a l'application d'une contrainte. A transducer compensating a deflection due to the application of stress. Ledit transducteur comprend un anneau de support (32) comportant une masse etalon (34) en porte-a-faux sur deux courbures (38) entre les aimants (26, 28) d'un stator dans lequel est monte le transducteur. Said transducer comprises a support ring (32) having a proof mass (34) in cantilever on two curvatures (38) between the magnets (26, 28) of a stator in which is mounted the transducer. La deflexion de l'anneau de support due a l'application d'une force non equilibree, est compensee soit par deplacement des plots (30) utilises pour monter l'anneau de support, soit par deplacement du centre de gravite de la capacitance (128) de la masse etalon, soit par modification de l'anneau de support pour menager une paire de bras (156) de couple, chaque approche assurant qu'un axe de deflexion (102, 130) de l'anneau de support est coaligne avec le centre de gravite de la capacitance reduisant ainsi au minimum une erreur de charge preliminaire dans la sortie du transducteur. The deflection of the support ring due to the application of an unbalanced force is compensated by either moving the pads (30) used to mount the support ring, or by moving the center of gravity of the capacitance ( 128) of the proof mass, or by modification of the support ring to arrange a pair of arms (156) of torque, each approach ensuring that a deflection axis (102, 130) of the support ring is coaligne with the center of gravity of the capacitance thus minimizing a bias error in the output of the transducer.

Stress compensated transducer.

A force rebalance accelerometer includes a proof mass suspended by one or more flexures between stationary mounted upper and lower excitation rings. Pick-off capacitance plates formed on opposing sides of the proof mass form capacitance elements whose capacitance varies in response to displacement of the proof mass to provide a displacement signal. The displacement signal is applied to one or more electromagnets, used to force the proof mass back to a null or at-rest position. The drive current applied to the electromagnets thus represents the force or acceleration applied to the accelerometer. The electromagnets include a magnet and a pole piece which forms a magnetic return path. In order to relieve stresses due to thermal expansion, the magnet is spaced apart from the pole piece to enable the bonding area to be constrained to a minimum which, in turn, reduces the overall stress on the accelerometer. In particular, a bead of relatively noncompliant epoxy is used for bonding the excitation ring and pole piece to the magnet. In order to further reduce thermal stresses, a ring of relatively compliant epoxy is disposed concentric to the noncompliant epoxy.

Low stress magnet interface

A flexure in a force transducer, as an inertial guidance accelerometer, for securing a force sensitive element to a mounting base includes one or more flexure sections having one or more recessed surfaces which are substantially coincident with the neutral bending plane of the flexure Electrically conductive coating on the recessed surfaces provide electrical connections to components located on the force sensitive element The conductive coatings on or near the neutral bending plane of the flexure sections minimizes bending moments caused by stresses set up between the conductive coatings and the flexure which may in turn lead to bias errors At the same time, the flexure configuration provides for the desired strength and spring rate for the force sensitive element

Force transducer flexure with conductors on surfaces in the neutral bending plane

A flexure reed in a force transducer, such as an inertial guidance accelerometer, for securing a force sensitive element 30 to a mounting base 32, includes one or more flexure sections 60, 62 having recessed surfaces which are closely adjacent to or substantially coincident with the neutral bending plane of the flexure. Electrically conductive coatings 47 on the recessed surfaces provide electrical connections to components 42 located on the force sensitive element 30. The location of the conductive coatings on or near the neutral bending plane of the flexure sections minimizes bias errors. A method of manufacture of such a flexure reed is also provided, by selective and simultaneous etching from opposite faces of the flexure reed blank.

Atherton Kim W

Papers

Force transducer flexure with conductors on surfaces in the neutral bending plane

Force transducer flexure reed bearing electrical connections

Federnde aufhaengung fuer kraftumformer