Pendular accelerometer sensor with conditional capacitive detection

Abstract

An accelerometer sensor includes a casing, a pendulum fixed to the casing, a movable electrode carried by the pendulum and connected to a detection circuit, a first electrode and a second electrode rigidly attached to the casing to form, with the moving electrode, two capacitors of variable capacitance depending on a distance between the electrodes. The accelerometer sensor further includes a control unit that carries out detection operations to measure the variable capacitances of the capacitors. The control unit also performs a control operation of the movable electrode depending on the capacitances measured by applying a logic signal for controlling a switch for selective connection of the fixed electrodes to an excitation circuit delivering a control signal to the fixed electrodes in order to keep the pendulum in a predetermined position.