Patent ID: 8471570

Claim:
System for detecting and locating a tactile approach or the presence of a body close to a surface (PAD, TCH) comprising at least one series of conductors (II, III, IV, V, VI, VII and VIII, IX, X, XI, XII) arranged in at least one plane, wherein the surface comprising such a plurality of conductors is associated with a touch detection device (TDS) comprising: a polarization path (P), a reference path (R) and a detection path (S), addressing means (ICX) for selecting among said plurality of conductors ( . . . , IV, V, VI, . . . , IX, X, XI, . . . ) at least one first conductor (V) by connecting it to the polarization path (P), at least one second conductor (IV) by connecting it to the reference path (R) and at least one third conductor (VI) by connecting it to the detection path (S), means (PUS, PDS) for polarizing the polarization path (P), and a device for detecting and quantifying an unbalance between the reference path (R) and the detection path (S) caused by the polarization of the polarization path (P) and by the tactile approach or presence of the body, in order to detect and locate the tactile approach or presence of the body, wherein said device for detecting and quantifying said unbalance comprises: comparison means (CC) receiving at respective inputs the reference and detection paths (R, S); variable transfer capacitance means (CPB) connected to at least one of the reference and detection paths; and a control unit (UC) connected between the comparison means and the variable transfer capacitance means and adapted to vary the variable transfer capacitance of said variable transfer capacitance means as a function of the result (Q) produced by the comparison means up to compensation of the unbalance.