Method for electronically recording a fingerprint image acquired by an electro-optical material

Abstract

A fingerprint image capture system comprises an electro-optical material which captures a static fingerprint image and an apparatus for converting the static fingerprint image into an electronic signal. The image capture system includes an electrode for contacting a finger, and a bias supply for creating an electric field where epidermal ridges contact the electro-optical material. A transistor array senses charge or optical density variations in the electro-optical material to create an electronic representation of the fingerprint image. An initialization electrode places the electro-optical material into a uniform condition prior to acquisition of the fingerprint image. A physical artifact of the fingerprint image can be archived by removing the electro-optical material from the system following the fingerprint image acquisition.

What is claimed is: 
     
         1 . A method for electronically recording a fingerprint image acquired by an electro-optical material, the method comprising:
 mechanically coupling a free surface of the electro-optical material to a transistor array, the array configured to sense an amount of electrical charge in proximity to pixels comprising the array; and   sequentially addressing the transistor array so as to couple the array transistors to charge sensing amplifier circuits.   
     
     
         2 . The method of  claim 1  wherein the electro-optical material is an electrophoretic material. 
     
     
         3 . The method of  claim 1  wherein the free surface of the electro-optical material is coupled to the transistor array while the fingerprint image is being acquired. 
     
     
         4 . The method of  claim 1  wherein the free surface of the electro-optical material is coupled to the transistor array after the fingerprint image has been acquired. 
     
     
         5 . The method of  claim 1  wherein the transistor array is a CMOS array fabricated on crystalline silicon. 
     
     
         6 . The method of  claim 1  wherein the transistor array is a thin film transistor (TFT) array fabricated on a flexible substrate.