Filing Information

Inventor(s)	Dale R. Setlak ·
Assignee(s)	Harris Corporation ·  View assignee updates
Attorney/Agent(s)	Allen, Dyer, Doppelt, Milbrath & Gilchrist, P.A. Attorneys at Law ·
Primary Examiner	Thomas D. Lee ·
Assistant Examiner	Wenpeng Chen ·
Application Number	US8592469
Filing date	01/26/1996
Issue date	10/05/1999
Predicted expiration date	01/26/2016
U.S. Classifications	382/312  · 382/124  ·
International Classifications	G06K 700  ·
Kind Code	A
International Classifications	382312;324;124-127;321;115;223;274;261;270;275;205;211 ·

Patent Family

Abstract

A fingerprint sensor includes an array of electric field sensing electrodes, a dielectric layer on the sensing electrodes with the dielectric layer for receiving a finger adjacent thereto, and a driver for applying an electric field drive signal to the sensing electrodes and adjacent portions of the finger so that the sensing electrodes produce a fingerprint image output signal. In one embodiment of the invention, the driver provides a coherent drive signal for the array. A respective shield electrode may be associated with each of the electric field sensing electrodes for shielding each electric field sensing electrode from adjacent sensing electrodes. Each shield electrode may be actively driven for further shielding. The fingerprint sensor preferably further includes a synchronous demodulator and contrast enhancer for more accurate output image signals. The fingerprint sensor may be effectively used to control access to a computer workstation. Method aspects are also disclosed.

Independent Claims | See all claims (51)

1. 1. A fingerprint sensor comprising:an array of electric field sensing electrodes;a dielectric layer on a first surface of said array of electric field sensing electrodes, said dielectric layer for receiving a finger adjacent thereto; andcoherent drive means for applying a coherent electric field drive signal to said array of electric field sensing electrodes and adjacent portions of the finger so that said array of electric field sensing electrodes produce a fingerprint image output signal, said coherent drive means comprisinga second dielectric layer on a second surface of said array of electric field sensing electrodes opposite the first surface, anda common drive electrode extending beneath at least a plurality of electric field sensing electrodes of said array of electric field sensing electrodes with the second dielectric layer therebetween so that the electric field drive signal radiates vertically between said common drive electrode and electric field sensing electrodes.
2. 17. A fingerprint sensor comprising:an array of electric field sensing electrodes;a dielectric layer on said electric field sensing electrodes, said dielectric layer for receiving a finger adjacent thereto;a respective shield electrode associated with each of said electric field sensing electrodes for shielding each electric field sensing electrode from adjacent electric field sensing electrodes; anddrive means for applying an electric field drive signal to said electric field sensing electrodes and adjacent portions of the finger, said drive means comprising a common drive electrode extending beneath at least a plurality of electric field sensing electrodes of said array of electric field sensing electrodes so that the electric field drive signal radiates vertically between said common drive electrode and electric field sensing electrodes for causing said electric field sensing electrodes to produce a fingerprint image output signal.
3. 29. A fingerprint sensor comprising:an array of electric field sensing electrodes;a dielectric layer on said electric field sensing electrodes, said dielectric layer for receiving a finger adjacent thereto;a respective shield electrode comprising electrically conductive material surrounding each of said electric field sensing electrodes for shielding each electric field sensing electrode from adjacent electric field sensing electrodes;active shield driving means for actively driving each of said shield electrodes; anddrive means for applying an electric field drive signal to said electric field sensing electrodes and adjacent portions of the finger, said drive means comprising a common drive electrode extending beneath at least a plurality of electric field sensing electrodes of said array of electric field sensing electrodes so that the electric field drive signal radiates vertically between said common drive electrode and electric field sensing electrodes for causing said electric field sensing electrodes to produce a fingerprint image output signal.
4. 39. A computer workstation comprising:a housing;a computer processor positioned within said housing;a display operatively connected to said computer processor;a keyboard operatively connected to said computer processor; andfingerprint sensor means operatively connected to said computer processor and mounted within said housing for protection thereby, said fingerprint sensor means comprising a finger sensing surface exposed through an opening in said housing;said computer processor comprising access control means for permitting operation of the computer workstation only upon determining a match between a fingerprint sensed by said fingerprint sensor means and an authorized reference fingerprint;said fingerprint sensor means comprisingan array of electric field sensing electrodes,a dielectric layer on a first surface of said array of electric field sensing electrodes, said dielectric layer for receiving a finger adjacent thereto, anddrive means for applying an electric field drive signal to said array of electric field sensing electrodes and adjacent portions of the finger so that said array of electric field sensing electrodes produce a fingerprint image output signal, said drive means comprising a second dielectric layer on a second surface of said array of electric field sensing electrodes opposite the first surface, and a common drive electrode extending beneath at least a plurality of electric field sensing electrodes of said array of electric field sensing electrodes with the second dielectric layer therebetween so that the electric field drive signal radiates vertically between said common drive electrode and electric field sensing electrodes.
5. 45. A method for sensing a fingerprint and generating a fingerprint image output signal, the method comprising the steps of:providing an array of electric field sensing electrodes with a dielectric layer on a first surface of said array of electric field sensing electrodes for receiving a finger adjacent thereto, and further comprising a second dielectric layer on a second surface of said array of electric field sensing electrodes opposite the first surface, and a common drive electrode extending beneath at least a plurality of said array of electric field sensing electrodes with the second dielectric layer therebetween; andapplying a coherent electric field drive signal to said array of electric field sensing electrodes and adjacent portions of the finger using the common drive electrode so that the electric field drive signal radiates vertically between the common drive electrode and electric field sensing electrodes to thereby cause said array of electric field sensing electrodes to produce a fingerprint image output signal.
6. 50. A method for sensing a fingerprint and generating a fingerprint image output signal, the method comprising the steps of:providing an array of electric field sensing electrodes with a dielectric layer on said electric field sensing electrodes for receiving a finger adjacent thereto and a common drive electrode extending beneath at least a plurality of said array of electric field sensing electrodes;applying an electric field drive signal to said electric field sensing electrodes and adjacent portions of the finger using the common drive electrode so that the electric field drive signal radiates vertically between the common drive electrode and electric field sensing electrodes to thereby cause said electric field sensing electrodes to produce a fingerprint image output signal; andshielding said electric field sensing electrodes by positioning a respective shield electrode surrounding each of said electric field sensing electrodes to shield each electric field sensing electrode from adjacent sensing electrodes.