Enhancement methods and devices for reading a fingerprint image
First Claim
1. A method for reading a fingerprint image in which:
- a light beam from a light source is directed and aimed through a lateral surface of a transparent platen having a superior surface parallel to an inferior surface;
said light is reflected inside the transparent platen between said parallel surfaces above a critical angle as the light does not leave the transparent platen and a condition of total internal reflection is satisfied;
a finger is pressed against the superior surface of the transparent platen in the area where the ridges of the finger make contact with the superior surface, whereby the light is reflected under the critical angle and the condition of total internal reflection is not satisfied as some light leaves the transparent platen trough the inferior surface;
said light which has left the transparent platen is focused by a focusing element to a light detector which has a solid state array of optical sensors as a reading element.
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Accused Products
Abstract
A fingerprint reading modular device capable of extracting and accurately reproducing and enhancing the ridge pattern on the skin of a fingertip is provided. A narrow illumination source spanning the width of the device is focused onto a movable glass or transparent platen, producing reflected rays containing fingerprint information, as the finger is placed on this platen. Reflected rays are focused by a Selfoc optic fiber lens array onto a linear array of solid state reading elements which convert the image of the fingerprint to electrical signals, producing a digital image for each line of information. The movable transparent platen has an initial position and a terminal position, such that the method of scanning begins with the finger pressed against the platen in its initial position and pushed until the platen reaches its terminal position, whereby the solid state elements read multiple lines of the finger as it moves towards the terminal position.
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Citations
3 Claims
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1. A method for reading a fingerprint image in which:
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a light beam from a light source is directed and aimed through a lateral surface of a transparent platen having a superior surface parallel to an inferior surface; said light is reflected inside the transparent platen between said parallel surfaces above a critical angle as the light does not leave the transparent platen and a condition of total internal reflection is satisfied; a finger is pressed against the superior surface of the transparent platen in the area where the ridges of the finger make contact with the superior surface, whereby the light is reflected under the critical angle and the condition of total internal reflection is not satisfied as some light leaves the transparent platen trough the inferior surface; said light which has left the transparent platen is focused by a focusing element to a light detector which has a solid state array of optical sensors as a reading element. - View Dependent Claims (2, 3)
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Specification