DOPPELT-INTEGRIERENDE SILICIUM-BESCHLEUNIGUNGSERFASSUNGSEINRICHTUNG

摘要

A double integrating silicon acceleration sensor which is solid state and micromachined measures the acceleration of an object and determines the distance travelled by that object through its trajectory. The sensor comprises a hermetically sealed container. The cavity within the container is divided by a flexible silicon diaphragm 12 into two separate cavities, one shallow 24 and the other deep 26. The two cavities are filled with a fluid which is relatively incompressible over the range of operating pressure. The fluid can only transfer between the two cavities through an orifice 18. Two capacitor plates form a capacitor within the shallow cavity. One of the plates 16 is secured adjacent to and opposite of the first plate 14 within the shallow cavity. Further capacitor plates 42, 44 within the deep cavity may also be provided. The flexible diaphragm has semi-spherical dimples, in a hexagonal close pack pattern in at least one face. When the accelerometer experiences an acceleration, the diaphragm deflects into the deep cavity forcing fluid from the deep cavity into the shallow cavity. The gap between the two capacitor plates increases causing a change in the total capacitance. This capacitance value is exactly proportional to the distance travelled by the object for constant acceleration, and is approximately proportional to the distance travelled for other acceleration pulses. When capacitor plates are also located in the deep cavity, a differential capacitance results.