Fingerprint identification system using a pliable optical prism

• US 4,120,585 A
• Filed: 11/19/1976
• Issued: 10/17/1978
• Est. Priority Date: 11/19/1976
• Status: Expired due to Term

• Current Assignee: Secure Technologies Group, Inc.
• Original Assignee: Calspan Corp (Transdigm Group Incorporated)
• Inventors: DePalma, Vito A., King, Raymond W.
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US05/743,424
• Time in Patent Office: 697 Days
• Field of Search: 356/71, 350/286, 350/287, 264/1, 340/146.3 E
• US Class Current: 356/71
• 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

A pliable optical prism for use in an optical imaging system such as a fingerprint reader where the prism is physically contacted and the nature of the contact determines the efficiency of the device. The pliable prism deforms under applied pressure to partially mirror the topographic configuration of the source of applied pressure.

Claims

1. A fingerprint based identification terminal including:

sensor means;

optically clear, pliable, resilient prism means;

light source means for shining onto one internal surface of said prism means and being internally reflected onto said sensor means in accordance with the topographic configuration of any member contacting the external surface corresponding to said one internal surface and any resulting deformation of said one internal surface;

whereby when a finger contacts a planar surface of said prism means corresponding to said one internal surface, said planar surface and thereby said internal surface will deform to partially mirror the ridge-valley configuration of the contacting finger to give a greater area of contact resulting in a high contrast image being reflected onto said sensor means due to absorption of light at said one internal surface where said planar surface is contacted by the finger.

2. The fingerprint based identification terminal of claim 1 further including transducer means for generating an actuating signal to activate said terminal when sufficient pressure is exerted by a finger against said prism means.

3. A fingerprint based identification terminal including:

first sensor means;

second sensor means;

optically clear, pliable and resilient prism means;

light source means for shining onto one internal surface of said prism means and being internally reflected onto said first sensor means;

housing means in direct contact with a portion of a planar surface of said prism means corresponding to said one internal surface;

whereby when a finger contacts said planar surface of said prism means, said planar surface and thereby said internal surface will deform to create an air gap between at least a portion of said prism means and said housing means to cause additional internal reflection of light from said light source means onto said second sensor means to cause the generation of a terminal activating signal and said deformation of said planar and inner surfaces partially mirroring the ridge-valley configuration of the contacting finger to give a greater area of contact resulting in a high contrast image being reflected onto said first sensor means due to absorption of light at said one internal surface where said planar surface is contacted by the finger.