DIFFERENTIALKONDENSATORMESSUMFORMER

摘要

A differential variable capacitance acceleration sensor includes a sandwich structure having three stacked plates (10, 40, 60) of silicon with the centre plate (10) mounted such that its centre portion (12) is enabled to move in a sealed cavity with each side thereof moving toward and away from a fixed cooperating plate (40, 60) forming the opposite side of a capacitive circuit. The centre portion (12) or mass of the centre plate (10) is suspended from its rim (14) by means of a large number of integral fingers (18, 20) extending from the rim (14) to the top and bottom surfaces of the centre portion (12). This centre mass (12) includes a number of through holes (16) to permit the passage of air from one side to the other and may also include grooves to aid in the flow of air. The fixed top plate (40) or lid and the base (60) also have, or may have, grooves (46, 66) to assist in the passage of air. The integral fingers (18, 20) are formed in sinuous curves or other form varying from straightness but having a significant tension such that when the centre mass (12) is displaced during a sensed acceleration, the fingers (18, 20) tend toward straightness. In an alternative embodiment, the fingers are bars (108) having corrugations stepped between different planes.