Detection method and apparatus for reduced cross-talk and asic area of a fingerprint sensor

摘要

A method and apparatus for electrical detection of a finger print has a reduced number of interconnect signals between a sensor area and a substrate and an electronic circuit for excitation and detection of the finger print compared to a single-chip finger print sensor. The individual signals are connected internally at the sensor substrate in such a way that the response from the individual sensor elements can be separated from each other. Cross-talk is reduced by keeping the sensor outputs at a constant potential, thus eliminating the effect of capacitive coupling between different sensor outputs and also between sensor outputs and a ground or reference potential.

主权项

1. A sensor for detection of a characteristic of an object, wherein the sensor is configured for concurrent detection of a plurality of sensor elements and is electrically connected to an electronic circuit; the sensor comprising:
a sensor surface adapted to accommodate the object for detection of the characteristic of the object; at least one sensor electrode located in a first position on the sensor surface, the at least one sensor electrode being configured to detect the characteristic of the object; a first excitation element electrically coupled to the at least one sensor electrode via a first impedance; a sensor input electrically connected to the first excitation element; a voltage or current source electrically connected to the sensor input and configured to provide a voltage or current signal; a first sensing element electrically coupled to the at least one sensor electrode via a second impedance; a first sensor output electrically connected to the first sensing element; and a first current amplifier electrically connected to the first sensor output; wherein a reference voltage is supplied by the electronic circuit to the first current amplifier, the reference voltage further being provided to the first sensor output by the first current amplifier; and wherein the at least one sensor electrode is configured to provide an output current via the first sensing element to the first sensor output, the output current being determined by the characteristics in response to the voltage or current signal.