Electric field fingerprint sensor apparatus and related methods
DCFirst Claim
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; and
coherent 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.
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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.
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Citations
51 Claims
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1. A fingerprint sensor comprising:
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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; and coherent 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 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A fingerprint sensor comprising:
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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; and drive 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. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A fingerprint sensor comprising:
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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; and drive 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. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A computer workstation comprising:
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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; and fingerprint 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 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, and drive 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. - View Dependent Claims (40, 41, 42, 43, 44)
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45. A method for sensing a fingerprint and generating a fingerprint image output signal, the method comprising the steps of:
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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; and applying 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. - View Dependent Claims (46, 47, 48, 49)
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50. A method for sensing a fingerprint and generating a fingerprint image output signal, the method comprising the steps of:
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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; and shielding 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. - View Dependent Claims (51)
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Specification