Patent ID: 6543285
Filing Date: 2003-04-08
Classification: G01C,G01P

Abstract:
A physical quantity detector apparatus that has a vibrator displaceably supported to a substrate and that detects a physical quantity in accordance with a displacement of the vibrator, the apparatus comprising:a comb-like fixed electrode fixed to the substrate and having a plurality of electrode fingers that extend from a basal portion of the fixed electrode in parallel to each other; and a comb-like movable electrode being displaceable together with the vibrator and having a plurality of electrode fingers that extend from a basal portion of the movable electrode in parallel to each other and that are inserted between the electrode fingers of the fixed electrode, wherein as a voltage is applied between the fixed electrode and the movable electrode, the movable electrode is displaced in a direction of an axis of each electrode finger, and wherein a distance D1 from a distal end surface of each electrode finger of the movable electrode to the basal portion of the fixed electrode facing the distal end surface of each electrode finger of the movable electrode, a distance D2 from a distal end surface of each electrode finger of the fixed electrode to the basal portion of the movable electrode facing the distal end surface of each electrode finger of the fixed electrode, a maximum displacement A of the movable electrode in the direction of the axis of each electrode finger, a width w of each electrode finger of the movable electrode and of each electrode finger of the fixed electrode, and a distance d between each electrode finger of the movable electrode and an adjacent electrode finger of the fixed electrode in a direction of the width satisfy a relationship of 1/(5dw)>{1/(D1âˆ’A)2}+{1/(D2âˆ’A)2} where a driving force electrode satisfies a relationship F=&egr;TV2/d and a derogatory electrostatic attraction force of the movable electrode satisfies a relationship F0=&egr;TwV2/(Dâˆ’A)2 so that the electrostatic attraction F0 is ignorable if F>10F0.