DEVICE FOR MEASURING A CAPACITY VARIATION, CAPACITIVE SENSOR INCLUDING SUCH DEVICE, AND RELATED METHOD

摘要

The invention relates to a device for measuring a capacity variation (Cx) in a capacitor (3) comprising a detection electrode (2) having a capacity that may vary in the vicinity of an object or a portion of a user's body, which comprises a means (S1) for applying a capacitor charge voltage (Vcc) provided by a voltage source (5), a means for establishing a charge transfer (S2) from the capacitor towards a reference capacity (Cs) arranged in parallel to said capacitor, a means for determining a number of charge transfers, from the capacitor to the reference capacity (Cs), necessary for reaching a predetermined threshold voltage (Vs) at the terminals of the reference capacity, wherein said device is characterised in that it comprises means for modifying the necessary number of charge transfers, including a second electrode (8) provided opposite the detection electrode (2) and a voltage generator (7) capable of supplying to said second electrode a voltage selected from a first high voltage (Vbatt) and a second low voltage (OV) in order to modulate the potential applied to said second electrode, said means being coupled without contact to the detection electrode (2) of the capacitor (3) in order to add or retrieve charges to/from said capacitor upon the establishment of charge transfers towards said reference capacity. The invention also relates to an associated method.