Patent ID: 6175641
Filing Date: 2001-01-16
Classification: A61B,G06K

Abstract:
A detector for recognizing the living character of a finger in an opto-electronic fingerprint recognizing apparatus, in which a full two-dimensional image of the fingerprint is captured, and in operation the detector is in contact with a print area of a living finger constituting a print forming element, the fingerprint recognizing apparatus comprises a print detector for examining said print area, the print detector having a print imaging surface partially covered by said print area, the detector comprising:an electrode system made of an electrically conductive material, and arranged on a portion of said print detector covered by said print area, and being coupled to said print imaging surface;an electrical evaluation unit coupled through electrical contacts to the electrode system, said electrical evaluation unit sensing a change in state of the electrode system caused by the proximity of the print forming element;wherein said electrode system comprises interdigital electrodes covered completely by a non-conductive layer; andwherein said print imaging surface is constituted by said electrically non-conductive and light transparent material comprised of a thin separate layer deposited on the print detector so as to cover at least a dominant portion of said print area, said electrode system and said electrical contacts, and said electrode system and said electrical contacts are made of light transparent and electrically conductive material configured to allow print images to be captured of the print forming element on at least one portion of the print area covered by said electrode system and said electrical contacts, and said electrode system is designed for determining dielectric constant.