Anticounterfeiting method and device utilizing holograms and pseudorandom dot patterns

• US 5,396,559 A
• Filed: 08/24/1990
• Issued: 03/07/1995
• Est. Priority Date: 08/24/1990
• Status: Expired due to Term

• Current Assignee: Stephen P. Mcgrew
• Original Assignee: Stephen P. Mcgrew
• Inventors: McGrew, Stephen P.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US07/574,647
• Time in Patent Office: 1,656 Days
• Field of Search: 380/6, 380/7, 380/9, 380/10, 380/23-25, 380/54, 380/59, 283/17, 283/73-78, 283/81, 283/86, 283/93
• US Class Current: 380/54
• CPC Class Codes: B42D 25/00 Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof printing processes to produce identification or security features B41M3/14
• CPC Class Codes: B42D 25/309 Photographs
• CPC Class Codes: B42D 25/328 Diffraction gratings; Holograms
• CPC Class Codes: B42D 25/485 by electronic processing means
• CPC Class Codes: G03H 1/0236 Form or shape of the hologram when not registered to the substrate, e.g. trimming the hologram to alphanumerical shape substrates bearing a hologram G03H1/0272
• CPC Class Codes: G03H 1/04 Processes or apparatus for producing holograms G03H1/26 takes precedence
• CPC Class Codes: G03H 1/2205 using downstream optical component
• CPC Class Codes: G03H 1/268 Holographic stereogram
• CPC Class Codes: G03H 2001/0016 Covert holograms or holobjects requiring additional knowledge to be perceived, e.g. holobject reconstructed only under IR illumination
• CPC Class Codes: G03H 2001/0022 Deciphering being performed with numerical or optical key, e.g. with the optical scrambler used during recording
• CPC Class Codes: G03H 2001/0224 Active addressable light modulator, i.e. Spatial Light Modulator [SLM]
• CPC Class Codes: G03H 2001/0413 for recording transmission holograms
• CPC Class Codes: G03H 2001/0497 Dot matrix holograms
• CPC Class Codes: G03H 2001/2244 Means for detecting or recording the holobject
• CPC Class Codes: G03H 2210/22 2D SLM object wherein the object beam is formed of the light modulated by the SLM
• CPC Class Codes: G03H 2210/54 For individualisation of product
• CPC Class Codes: G03H 2223/12 Amplitude mask, e.g. diaphragm, Louver filter
• CPC Class Codes: G03H 2227/06 Support including light source
• CPC Class Codes: G06K 19/10 at least one kind of marking being used for authentication, e.g. of credit or identity cards verification of coded identity or credit cards in mechanisms actuated by them G07F7/12
• CPC Class Codes: G07C 9/253 visually

Abstract

A security device for use on identification cards, monetary documents, and the like using a reference pattern and a message pattern each having the appearance of a random pattern of dots. The reference pattern is a dense pattern of randomly positioned dots, and the message pattern is a modulated version of the reference pattern in which the dots of the reference pattern are slightly repositioned by an amount depending on the grey value or color value of a message image at each dot location. The message image is decrypted and becomes visible with a range of grey values when it is viewed through a film transparency of the reference pattern. The dot pattern may be printed, embossed or recorded as a photograph or a hologram. Decryption of the message image may be accomplished by viewing through a contact mask, superposition of images of the message pattern and reference pattern, by viewing the message pattern through a mask positioned at a real image of the reference pattern, or like means.

Claims

1. An anticounterfeiting security method comprising:

means for extracting information from a document to use as a kernel for generating a pseudorandom reference dot pattern,

means for generating a pseudorandom reference dot pattern from said kernel,

means for modulating said reference dot pattern as an encrypted message dot pattern to encrypt a message and

means for applying said message dot pattern to said document in an optically detectable form.

2. The method of claim 1, further comprising means for reading said message dot pattern and means for comparing said message dot pattern to said reference dot pattern, thereby decoding said message.

3. The method of claim 2, said comparing being accomplished by illuminating said message pattern with light corresponding to said reference pattern.