Method for capture of a fingerprint using an electro-optical material
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.
1. A method for acquisition of a static fingerprint image onto an artifact comprising an electro-optical material, the method comprising:
connecting a first node of a direct current (DC) potential to a finger;
coupling a second node of the direct current (DC) potential to an electrophoretic display, the electrophoretic display comprising:
an electro-optical material that exhibits a change in visible appearance in response to the application of an electric field;
a transparent protective layer;
a transparent electrode layer;
wherein the electro-optical material comprises micro-capsules in contact with the transparent electrode layer that comprise negatively charged dark pigment suspended in a transparent fluid;
bringing the finger into contact with a free surface of the electrophoretic display, thereby completing an electrical circuit between the first node and second node of the DC potential, wherein completing the electrical circuit between the first node and second node of the DC potential applies a positive charge to the free surface of the electrophoretic display resulting in the dark pigment of the microcapsules becoming visible at the surface of the electrophoretic display merely at a location of contact of the finger with the surface of the electrophoretic display, due to the negative charge of the dark pigment, thereby generating a fingerprint image;
capturing an image of the fingerprint image using an imaging apparatus;
storing the captured image electronically; and
decoupling the electro-optical material from the direct current (DC) potential following the acquisition of the fingerprint image.
2. The method of claim 1 , wherein the electro-optical material comprises positively charged white pigments.
3. The method of claim 1 , wherein the electro-optical material is an electrochromic material.
4. The method of claim 1 , wherein the electro-optical material utilizes total internal reflection.
5. The method of claim 1 , further comprising;
removing the fingerprint image artifact is removed from an acquisition device and;
a pre-initialized coupon of the electro-optical material is replaced into the acquisition device.
6. The method of claim 1 , wherein the finger is rotated after contact with the free surface of the electro-optical material so as to increase the total area imaged.