Accelerometer with reduced extraneous vibrations owing to improved electrode shape

• Main Authors: MOREAU MAURICE, MENARD JEAN-PAUL
• Format: Patent
• Language: English
• Published: 21.09.2010
• Subjects: INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT; MEASURING; MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION,OR SHOCK; MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICALDEVICES; MICROSTRUCTURAL TECHNOLOGY; PERFORMING OPERATIONS; PHYSICS; TESTING; TRANSPORTING

The invention relates to an accelerometer comprising a moving mass (5) and a fixed part (2), which uses variations in capacitance (3, 4) in order to detect the movement of the mass (5). The inventive accelerometer comprises a first series of electrodes (4) which are solidly connected to the mass (5) and which are interdigitated with a series of electrodes (3, 7) which are solidly connected to the fixed part (2). According to the invention, each moving electrode (4), together with an adjacent fixed electrode (3), forms a capacitance which varies according to the position of the moving mass (5). The accelerometer further comprises an electronic circuit which is used to detect the variation in at least one capacitance between the moving mass (5) and the fixed part (2), in the form of a moving mass displacement indicator. The invention is characterised in that one or more or the electrodes (3, 4) or the moving mass (5) and/or the fixed part (2) takes the form of a finger with a large base and a profile which narrows in the direction of the free end thereof. Moreover, the recurring return stress can be selected such that the mechanical power has an essentially zero power zone at the mechanical resonance frequency of the electrodes.