PATTERN CLASSIFICATION APPARATUS

• US 3,604,806 A
• Filed: 10/09/1968
• Issued: 09/14/1971
• Est. Priority Date: 10/09/1968
• Status: Expired due to Term

• Current Assignee: John David Redman
• Original Assignee: John David Redman
• Inventors: Redman, John David
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Major, T.
• Application Number:
  US04/766,185
• Time in Patent Office: 1,070 Days
• Field of Search: 356/71,106 250/219,233
• US Class Current: 356/71
• CPC Class Codes: G01N 21/5911 of the scanning type scanning per se G02B
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G06V 10/88 Image or video recognition using optical means, e.g. reference filters, holographic masks, frequency domain filters or spatial domain filters
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition

Abstract

The apparatus uses a beam of collimated light, e.g. from a laser, to produce a diffraction image of the pattern, e.g. a transparent fingerprint. This image is effectively scanned, either mechanically by a light filter or filters which rotate relative to the image, in which case the transmitted light is converted to a cyclically varying electrical signal which can be frequency analyzed into components characteristic of the pattern, or statically by concentric arrays of photosensitive devices whose DC outputs are characteristic of the spatial frequencies of the pattern.

Claims

1. Apparatus for pattern classification comprising means for providing a beam of collimated light, means for locating a pattern relative to said beam to produce a diffraction image from said pattern, a plurality of rings of photosensitive devices positioned to receive said diffraction image thereupon with the rings concentric with the axis along which the image is projected, and means for combining outputs from the devices in selected sectors of said rings to produce an output corresponding to the amplitude of at least one selected spatial frequency in the annular portion of the image which is superimposed on one of said rings.

2. Apparatus as claimed in claim 1, wherein said pattern is a transparency.