Patent ID: 7797998
Filing Date: 2010-09-21
Classification: B81B,G01P

Abstract:
1. An accelerometer with moveable mass ( 5 ) and fixed part ( 2 ) using variations in capacitance ( 3 , 4 ) to detect the movement of the mass ( 5 ), in which a first series of electrodes ( 4 ) solidly connected to the mass ( 5 ) is interdigitated with a series of electrodes ( 3 , 7 ) solidly connected to the fixed part ( 2 ), each moveable electrode ( 4 ) forming, together with an adjacent fixed electrode ( 3 ), a variable capacitance varying as a function of the position of the moveable mass ( 5 ), the accelerometer furthermore comprising an electronic circuit that detects the variation in at least one capacitance between moveable mass ( 5 ) and fixed part ( 2 ), said electronic circuit acting as an indicator of the displacement of the moveable mass characterized in that at least one electrode ( 3 , 4 ) of the moveable mass ( 5 ) and/or of the fixed part ( 2 ) each exhibit a finger shape with a wide base and with a profile narrowing in the direction of their free end, and the electronic circuit generates a repetitive electrostatic restoring force and in that the repetitive electrostatic force is specifically chosen so that a mechanical power frequency spectrum ( 10 , 201 ) of said repetitive electrostatic force exhibits a zone with substantially zero power at a mechanical resonant frequency of the electrodes ( 4 ) of the moveable mass ( 5 ) and/or of the fixed part ( 2 ).