Patent ID: 6483931
Filing Date: 2002-11-19
Classification: G06F,G06K,H01L

Abstract:
A method of providing electrostatic discharge for a capacitive fingerprint pattern detecting array, comprising:providing a fingerprint pattern detecting array having a number of individual skin-distance sensing cells that are arranged in a closely spaced physical configuration; providing a dielectric layer for said array, said dielectric layer having an upper surface and a lower surface; placing a fingertip having said fingerprint pattern on said upper surface; providing each sensing cell with an amplifier having an ungrounded input node and an ungrounded output node; providing ungrounded output node-to-input-node feedback for each of said amplifiers, said feedback being sensitive to said fingerprint pattern; providing said feedback for each of said amplifiers by way of a first capacitor plate that is placed within said dielectric layer vertically under said upper surface and above the lower surface of said dielectric layer and is connected to said ungrounded input node, a second capacitor plate that is placed within said dielectric layer vertically under said upper surface and above the lower surface of said dielectric layer in close horizontal spatial relation to said first capacitor plate and is connected to said ungrounded output node, and said fingertip in vertical spatial relation with said first and second capacitor plates; providing a conductive path within said dielectric layer vertically under said upper surface and above the lower surface of said dielectric layer, said conductive path being peripherally contiguous with each of said first and second capacitor plates to spatially surround but not physically engage said first and second capacitor plates; and connecting said conductive path to ground, to thereby protect said input and output nodes from electrostatic potential that may be carried by said fingertip by providing an electrostatic discharge path for said electrostatic potential.