Patent · US Expired

Capacitive sensor system with improved capacitance measuring sensitivity

US7256589B2 · kind B2 · utility

12Cited by
96References
42Claims
0Family size

Assignee

Inventor

Key dates

Filing dateApr 25, 2002
Grant dateAug 14, 2007
Priority date—
Expiry dateApr 25, 2022

Classification

  • Technology area (CPC G)Physics
  • CPC primaryG01L1/146
  • WIPO fieldMeasurement
  • WIPO sectorInstruments

Abstract

A capacitance sensor system and method includes a capacitive sensor as an array of sensor electrodes near the surface of the integrated circuit and charge pump circuits for measuring the capacitance at each sensor electrode. Shield electrodes and unused sense electrodes are used for background capacitance cancellation at each array location. The shield electrodes are switched between the circuit supply potentials in a manner synchronous to the capacitance sensing at the sense electrodes. The improved background capacitance cancellation allows all circuitry to be located outside the sensor array. The capacitance data is used to determine the positions of fingerprint artifacts and other fingerprint features.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.