Patent ID: 7088114

Claim:
In a fingerprint sensor having a plurality of pixels for sensing a fingerprint of a user's finger, each pixel having a sensing element coupled to an amplifier for generating an output corresponding to a fingerprint characteristic appearing at the pixel location, the sensing element comprising: a body of dielectric material; a surface plate of conductive material retained by the dielectric body and having an upper surface defining a sensing surface for contact with the fingerprint-bearing skin of a user's finger; first and second coplanar electrodes embedded in the dielectric body at a first level below the surface plate; and a third electrode embedded in the dielectric body at a second level below the surface plate, the third plate being connected by a conductor to the surface plate; wherein a first sensor is formed by the third electrode and the first electrode, a second sensor is formed by the third electrode and the second electrode, and a fingerprint sensor is formed between the surface plate and the skin of the user's finger thereover during a sensing operation.