Extended fingerprint reading apparatus

• US 5,818,956 A
• Filed: 10/23/1995
• Issued: 10/06/1998
• Est. Priority Date: 10/23/1995
• Status: Expired due to Fees

• Current Assignee: Raja Singh Tuli
• Original Assignee: Raja Singh Tuli
• Inventors: Tuli, Raja Singh
• Primary Examiner(s): Kelley, Christopher S.
• Application Number:
  US08/546,787
• Time in Patent Office: 1,079 Days
• Field of Search: 382/124, 382/125, 382/126, 382/127, 356/71, 250/206.1, 340/825.34, 348/161
• US Class Current: 382/126
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence

Abstract

The present invention is a miniature fingerprint reading device capable of extracting and accurately reproducing the ridge orientations on the skin of a fingertip. The illumination, focusing and reading elements follow the finger'"'"'s curvature to provide a much larger surface area fingerprint comparable to conventional inking methods. The present invention virtually eliminates the occurrence of skewed images as there are restrictions to the angle at which any finger is read. Trapezoidal distortion is also eliminated as the fingerprint image is always at a fixed distance from the reading elements.

Claims

1. A fingerprint reading device comprising:

a transparent flexible membrane of uniform thickness which when depressed follows the profile of a finger, making full contact with the fingerprint area including the sides of the finger;

said transparent flexible membrane fixed to a housing inside which an illumination source, a Selfoc optic fibre lens array, and a linear array of reading elements remain fixed relative to each other, traversing in a path identical to the curvature of the transparent membrane from one side of the finger to the other where contact is made, equidistant to the transparent flexible membrane throughout the path traversed;

said reading elements which read one line of the fingerprint at a time, whereby each line is parallel to the long axis of the finger, advancing to consecutive lines upon completing the reading operation for each line;

said illumination source which directs a linear beam of light to the fingerprint, is focused by a Selfoc lens array on the reading elements to produce outputs proportional to the intensity of incident light for each picture element, creating a digital representation of each line.

3. A fingerprint reading device as claimed in claim 1 whereby a patterned strip of alternate dark and light elements on the transparent surface upon which the finger rests, is read by optical sensor elements which align the fingerprint image to this pattern.

4. A fingerprint reading device as claimed in claim 1 whereby the reading elements are comprised of a Charged Coupled Device, and the focusing means is comprised of an optic lens system.

2. A fingerprint reading device comprising:

a transparent circular or elliptical tube of uniform thickness which follows the profile of a finger when inserted inside said tube, making full contact with the fingerprint area including the sides of the finger;

said transparent circular or elliptical tube rotating within a housing inside which an illumination source, a Selfoc optic fiber lens array, and a linear array of reading elements remain fixed within the housing, with the finger rotating past the reading elements due to the applied force of the finger, producing sufficient friction without slipping against the contacted surface area, such that the transparent circular tube remains at a fixed distance from the Selfoc optic fiber lens array throughout its rotation;

said reading elements which read one line of the fingerprint at a time, whereby each line is parallel to the long axis of the finger, reading consecutive lines as the finger is rotated;

said illumination source which directs a linear beam of light to the fingerprint, is focused by a Selfoc lens array on the reading elements to produce outputs proportional to the intensity of incident light for each picture element, creating a digital representation of each line;

whereby a patterned strip of alternate dark and light elements on the transparent surface upon which the finger rests, is read by optical sensor elements which align the fingerprint image to this pattern.