PROCEDURE DETERMINING VERY LOW CAPACITANCE AND ITS APPLICATION Russian patent published in 2003 - IPC

FIELD: surface sensors for capacitive measurements, specifically, sensors of finger prints. SUBSTANCE: raster of capacitor plates is connected to reading and excitation conductors. Reading conductors LL. are connected in alteration to output of operational amplifier with feedback and to reservoir capacitor (C_s). Measured capacitances (C_p) are charged many times and charges are stored in reservoir capacitors. Potential across reading wires between charging cycles is maintained constant thanks to low-resistance output of operational amplifier. EFFECT: capability to evaluate jointly all reading conductors when procedure is utilized in sensor of finger prints. 3 cl, 11 dwg