Resistive finger detection for fingerprint sensor
AssigneeSTMicroelectronics S.r.l.
InventorGiovanni Gozzini
Life of this patent
Estimating the term…
Abstract
Within a capacitive fingerprint detection device, finger detection is provided by a plurality of resistive grids overlying the fingerprint sensor electrodes to measure the resistance of the finger placed on the sensor surface. A finger placed on the sensor surface connects the resistive rids and allows the skin resistivity to be measured. The measured resistance is compared to a reference resistance or range of resistances to determine whether the measured resistance matches the expected bio-characteristics of living skin tissue. The finger detection thus provides anti-spoofing protection for the fingerprint detection device.
Claims20
A method of finger detection, comprising:
- measuring a resistance between at least two isolated resistive grids on a sensing surface of a capacitive fingerprint detection device when connected by an object placed on the sensing surface of the fingerprint detection device, wherein the capacitive fingerprint detection device includes a plurality of capacitive sensor electrodes below the resistive grids for detecting fingerprint features;
- comparing the measured resistance to a resistance range corresponding to living skin tissue to determine whether a finger has been placed on the surface of the fingerprint detection device.
Anti-spoofing protection for a fingerprint detection device, comprising:
- a plurality of resistive grids overlying capacitive sensor electrodes employed within the fingerprint detection device to detect fingerprint features on a sensing surface of the fingerprint detection device;
- resistance measurement means measuring a resistance between two of the resistive grids when an object on the sensing surface electrically connects the two resistive grids;
- and
- comparator means comparing the measured resistance to resistive bio-characteristics of living skin tissue to determine whether the object on the sensing surface of the fingerprint detection device is a finger.
A fingerprint detection device, comprising:
- capacitive sensor electrodes employed to detect fingerprint features;
- a plurality of resistive grids on a sensing surface of the fingerprint detection device and overlying the capacitive sensor electrodes;
- resistance measurement means measuring a resistance between two of the resistive grids when an object on the sensing surface electrically connects the two resistive grids;
- and
- comparator means comparing the measured resistance to resistive bio-characteristics of living skin tissue to determine whether the object on the sensing surface of the fingerprint detection device is a finger.
Dependencies are inferred from the claim text.