Patent application number | Description | Published |
20080295622 | PLANAR RESONATOR GYROSCOPE CENTRAL DIE ATTACHMENT - Packaging techniques for planar resonator gyroscopes, such as disc resonator gyroscopes (DRGs) are disclosed. A gyroscope die may be attached to its package substrate on a central disc area that is inboard of its embedded electrodes. This configuration eliminates contact of the die with the package substrate beneath the embedded electrodes allowing the internal electrode support structure to expand or contract freely without stress as its temperature changes. The central attachment can also be used diminish the package temperature gradients on the periphery of the die, if the thermal conductivity of the central disc attachment material is higher than the package substrate. Temperature gradients across the resonator also lead to thermoelastic damping asymmetry and rate drift. In addition, the electrical connections to the die may be formed by vertical vias within the central disc attachment area or by thin wirebonds to peripheral I/O pads on the gyro chip. | 12-04-2008 |
20090301193 | FREQUENCY TUNING OF DISC RESONATOR GYROSCOPES VIA RESONATOR MASS PERTURBATION BASED ON AN IDENTIFIED MODEL - Techniques for reducing the frequency split between the Coriolis-coupled modes in disc resonator gyroscopes (DRGs) by perturbing the mass distribution on the disc resonator based on an identified model are disclosed. A model-identification method of tuning a resonator comprises perturbing the mass and measuring a frequency response matrix of the resonator. The frequency response matrix includes a plurality of inputs and a plurality of outputs and the resonator has a plurality of coupled resonance modes. A reduced structural mechanics matrix model of the resonator in sensor and actuator coordinates is identified from the measured frequency response matrix and analyzed to determine generalized eigenvectors of the structural mechanics model and their variations due to selected mass perturbations which is then estimated to improve degeneracy of the plurality of coupled resonance modes based on the generalized eigenvectors of the mass and the stiffness. | 12-10-2009 |
20090301194 | SYSTEMATIC DISC RESONATOR GYROSCOPE TUNING - Tuning an axisymmetric resonator such as in a disc resonator gyroscope (DRG) is disclosed. Frequency tuning a DRG in a single step informed by a systematic physical model of the resonator structure, sensing and actuation elements, such as a finite element model, is provided. The sensitivity of selected trimming positions on the resonator to reducing asymmetry terms is determined via perturbations of the systematic model. As well, the dependence of the parameters of model transfer functions between actuation and sensing elements on resonator asymmetry are systematically determined. One or two measured transfer functions may then be analyzed according to the systematic model to fully determine the needed asymmetry correction components of the DRG. One or two of four groups of four electrostatic bias electrodes or four groups of four laser trimming locations for the DRG are utilized to correct the asymmetry components which can give rise to mistuning. | 12-10-2009 |
20100024546 | DISC RESONATOR INTEGRAL INERTIAL MEASUREMENT UNIT - Sensing motion of multiple degrees of freedom for an integral inertial measurement unit provided through the operation of a single centrally mounted planar disc resonator having a single driven mode in a single vacuum enclosure is disclosed. The resonator comprises a circumferentially slotted disc having multiple internal capacitive electrodes within the slots in order to excite a single in-plane driven vibration and sense in-plane vibration modes or motion of the resonator. In addition, vertical electrodes disposed below and/or above the resonator may also be used to sense out-of-plane vibration or motion. Acceleration sensing in three orthogonal axes can be obtained by sensing two lateral modes of the disc resonator in the plane of the disc from the internal electrodes and a vertical mode from the vertical electrodes. | 02-04-2010 |
20100251817 | THERMAL MECHANICAL ISOLATOR FOR VACUUM PACKAGING OF A DISC RESONATOR GYROSCOPE - A single layer micromachined thermal and mechanical isolator may be bonded between a microelectromechanical system (MEMS) die and package. Small bond pads of the isolator are attached to the periphery of the die. The isolator material may be chosen to match that of the die, reducing CTE mismatch. Long thin isolation beams can be used to provide thermal isolation against external temperature changes, which may be conducted through the package. Weak and flexible beams can be used to tolerate large displacements with very little resistance. Thus, excessive stress or distortion to the package, from either CTE mismatch or external stress, may be absorbed by the isolator and will not be transmitted to the MEMS die. Beam rigidity may be designed to attenuate vibration of particular frequency range. The isolator can be readily inserted into an existing disc resonator gyroscope package in one thermal compression bond step. | 10-07-2010 |
20100251818 | ENVIRONMENTALLY ROBUST DISC RESONATOR GYROSCOPE - Micromachined disc resonator gyroscopes (DRGs) are disclosed designed to be virtually immune to external temperature and stress effects. The DRG is a vibratory gyroscope that measures angular rate which is designed to have reduced sensitivity to external thermal and mechanical stress. The DRG features an integrated isolator that may be fabricated on the same wafer as the electrode wafer forming a plurality of integrated isolator beams. In addition, the DRG may include a wafer level hermetical vacuum seal, flip chip ball grid array (BGA), and vertical electrical feedthrough to improve reliability and to reduce manufacturing cost. An additional carrier layer may be used with shock stops, vertical electrical feedthrough, and the flip chip BGA. A pyrex or quartz cap with embedded getter and shock stops can be employed. | 10-07-2010 |
20100300201 | ISOLATED ACTIVE TEMPERATURE REGULATOR FOR VACUUM PACKAGING OF A DISC RESONATOR GYROSCOPE - A micromachined thermal and mechanical isolator for MEMS die that may include two layers, a first layer with an active temperature regulator comprising a built-in heater and temperature sensor and a second layer having mechanical isolation beams supporting the die. The isolator may be inserted between a MEMS die of a disc resonator gyroscope (DRG) chip and the leadless chip carrier (LCC) package to isolate the die from stress and temperature gradients. Thermal and mechanical stress to the DRG can be significantly reduced in addition to mitigating temperature sensitivity of the DRG chip. The small form can drastically reduce cost and power consumption of the MEMS inertial sensor and enable new applications such as smart munitions, compact and integrated space navigation solutions, with significant potential cost savings over the existing inertial systems. | 12-02-2010 |