Apparatus and methods for fluorescent imaging and optical character reading

• US 5,719,948 A
• Filed: 06/24/1994
• Issued: 02/17/1998
• Est. Priority Date: 06/24/1994
• Status: Expired due to Term

• Current Assignee: Angstrom Technologies, Inc.
• Original Assignee: Angstrom Technologies, Inc.
• Inventors: Liang, Louis H.
• Primary Examiner(s): Couso, Jose L.
• Assistant Examiner(s): Do, Anh Hong
• Application Number:
  US08/265,399
• Time in Patent Office: 1,334 Days
• Field of Search: 382/100, 382/112, 382/181, 340/825.34, 355/52, 250/252.1, 380/23, 283/88, 283/72
• US Class Current: 382/112
• CPC Class Codes: B41M 3/144 using fluorescent, luminescent or iridescent effects
• CPC Class Codes: G06K 7/12 using a selected wavelength, e.g. to sense red marks and ignore blue marks
• CPC Class Codes: G07D 7/12 Visible light, infrared or ultraviolet radiation
• CPC Class Codes: G07D 7/121 Apparatus characterised by sensor details
• CPC Class Codes: G07F 7/086 by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10

Abstract

An authentication system combines a source of ultraviolet light (and optionally a scanning mechanism) with apparatus for capturing and recognizing either graphic images or characters or both, where the graphic images and/or characters have been previously made with fluorescent substances that may be invisible under ordinary visible light, but are rendered detectable by the ultraviolet light. As in conventional optical character recognition (OCR), the characters may be conventional alphanumeric characters readable by human readers once they are made visible. The authentication system has a housing enclosing its optical path, a source of UV light, a detector for detecting graphic images or characters, conversion of the detector signal to digital form, a memory storing predetermined indicia, recognition logic, and indicating means. The system may also include a scanning mechanism and optical filters to select predetermined wavelengths of fluorescent light. The detector may be capable of detecting both fluorescent images and normal visible images, and the authentication system may incorporate switching mechanisms to allow multiplexed acquisition of fluorescent and normally visible images. The authentication system can operate in conjunction with a process for marking articles with indicia selected from a predetermined set of graphic images and characters readable by optical character recognition and/or by image comparison. That process can include printing fluorescent graphic images or characters in registration with (or with predetermined offset from) visible images or characters or indicia printed with substances fluorescent at different wavelengths. The recognition logic of the authentication system can include comparison of fluorescent and visible images or two different fluorescent images with each other. Pairs of indicia to be recognized and/or compared may be arranged to constitute a stereogram or other arrangement for first-order authentication by a human observer.

Claims

1. An authenticatable document for identification or for use in financial transactions, comprising:

a) a substrate suitable for printing with fluorescent ink, and

b) selected indicia printed on said document with fluorescent ink containing predetermined concentrations of one or more fluorescent substances, both said selected indicia and said fluorescent substances encoding predetermined characteristics of said authenticatable document,

said selected indicia being selected from predetermined sets of characters readable by means for optical character recognition and of graphic images recognizable by means for image comparison, wherein said selected indicia are printed in predetermined offset from registration with images or characters previously printed with visible substances, and wherein said selected indicia, in combination with said images or characters previously printed with visible substances, together form a stereogram when viewed from a standard near-point reading distance of 25 centimeters.

2. An authenticatable document as in claim 1, wherein said stereogram is a random-dot stereogram.

3. An authenticatable document as in claim 1, wherein said substrate is a material selected from the list consisting of cardboard, fabric, plastic, ceramic, metal, glass, rag paper, linen paper, mixed pulp and rag paper, recycled paper, vellum, synthetic paper, currency paper, security paper and tamper-resistant paper.

4. An authenticatable document for identification or for use in financial transactions, comprising:

a) a substrate suitable for printing with fluorescent ink, and

b) selected indicia printed on said document with fluorescent ink containing predetermined concentrations of one or more fluorescent substances, both said selected indicia and said fluorescent substances encoding predetermined characteristics of said authenticatable document,

said selected indicia being selected from predetermined sets of characters readable by means for optical character recognition and of graphic images recognizable by means for image comparison, wherein said selected indicia are printed in predetermined offset from registration with images or characters previously printed with fluorescent substances of different characteristic fluorescent wavelength from said selected indicia, and wherein said selected indicia, in combination with said images or characters previously printed with fluorescent substances of different characteristic fluorescent wavelength from said selected indicia, together form a stereogram when viewed from a standard near-point reading distance of 25 centimeters.

5. An authenticatable document as in claim 4, wherein said stereogram is a random-dot stereogram.

6. An authenticatable document as in claim 4, wherein said substrate is a material selected from the list consisting of cardboard, fabric, plastic, ceramic, metal, glass, rag paper, linen paper, mixed pulp and rag paper, recycled paper, vellum, synthetic paper, currency paper, security paper and tamper-resistant paper.