The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 04, 1999
Filed:
May. 09, 1997
Ellis Betensky, Toronto, CA;
Cross Check Corporation, North Palm Beach, FL (US);
Abstract
Lens systems for use in fingerprint detection systems employing frustrated total internal reflection are provided. The systems include an aperture stop and three lens units. The first lens unit has a positive power, is located on the object side of the aperture stop, and forms a telecentric pupil for the lens system. The second lens unit has a positive power, is located on the image side of the first lens unit, and forms a real image of the object. In certain embodiments, the third lens unit is located between the first and second lens units and has substantially afocal cylindrical power. In other embodiments, the third lens unit serves to correct the field curvature of the image contributed by the first and second lens units.