Counterfeit detection system

• US 6,483,576 B1
• Filed: 12/10/1999
• Issued: 11/19/2002
• Est. Priority Date: 12/10/1999
• Status: Expired due to Term

• Current Assignee: VerifyMe, Inc.
• Original Assignee: Laserlock Technologies Incorporated
• Inventors: Gardner, Norman A.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Smith, Zandra V.
• Application Number:
  US09/458,850
• Time in Patent Office: 1,075 Days
• Field of Search: 356/71, 356/376, 356/402, 250/556, 250/458.1, 250/461.1, 250/461.2, 382/115, 382/116, 382/137, 382/140
• US Class Current: 356/71
• CPC Class Codes: B41M 1/04 Flexographic printing
• CPC Class Codes: B41M 3/14 Security printing securities B42D25/29
• CPC Class Codes: B41M 3/142 using chemical colour-formers or chemical reactions, e.g. leuco-dye/acid, photochromes
• CPC Class Codes: B41M 3/144 using fluorescent, luminescent or iridescent effects
• CPC Class Codes: C09D 11/037 characterised by the pigment
• CPC Class Codes: C09D 11/322 Pigment inks
• CPC Class Codes: C09D 11/50 Sympathetic, colour changing or similar inks
• 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

A method for associating source information with a substrate includes providing at least one latent marking agent that emits a signal at an emission wavelength in response to being irradiated with infrared radiation at an excitation wavelength, wherein the signal is at least a portion of the source information; and affixing the at least one latent marking agent to the substrate. The at least one latent marking agent includes an inorganic pigment. In some embodiments of the method, the latent marking agent must be exposed to ultraviolet radiation before it can emit a signal in response to infrared irradiation.

Claims

1. A method for associating source information with a substrate, said method comprising:

providing at least one latent marking agent containing an inorganic pigment that fluoresces at a first emission wavelength in response to illumination at a first excitation wavelength, and also fluoresces at a second emission wavelength in response to illumination at a second excitation wavelength, wherein the first and second excitation wavelengths are unequal and are outside of a visible spectrum, and the first and second emission wavelengths are unequal and are within the visible spectrum;

affixing said at least one latent marking agent to said substrate;

detecting said at least one latent marking agent for distinguishing said substrate from other similar substrates, by applying each of said first and second excitation wavelengths, one at a time, and monitoring for corresponding fluorescence at the first and second emission wavelengths, respectively; and

,

wherein at least one of said excitation wavelengths is an infrared wavelength beyond said visible spectrum.

2. The method of claim 1, wherein applying at least one of said excitation wavelengths comprises illumination of the substrate with a laser.

3. The method of claim 1, wherein said inorganic pigment is at least one member selected from the group consisting of chelated rare earth metals, yttria phosphors, inorganic phosphors, Cartax CXDP and UV visible Eccowhite.

4. The method of claim 1, wherein said first emission wavelength and said second emission wavelength differ by at least 5 η

m.

5. The method of claim 1, wherein said first emission wavelength and said second emission wavelength differ by at least 50 η

m.

6. The method of claim 1, wherein one of said excitation wavelengths is about 915 η

m to about 990 η

m.

7. The method of claim 1, wherein one of said excitation wavelengths is about 1550 η

m to about 1800 η

m.

8. A method for associating source information with a substrate, said method comprising:

providing at least one latent marking agent containing an inorganic pigment that fluoresces at a first emission wavelength in response to illumination at a first excitation wavelength, and also fluoresces at a second emission wavelength in response to illumination at a second excitation wavelength, wherein the first and second excitation wavelengths are unequal and are outside of a visible spectrum, and the first and second emission wavelengths are unequal and are within the visible spectrum;

affixing said at least one latent marking agent to said substrate;

detecting said at least one latent marking agent for distinguishing said substrate from other similar substrates, by applying each of said first and second excitation wavelengths, one at a time, and monitoring for corresponding fluorescence at the first and second emission wavelengths, respectively; and

,

wherein said first and second excitation wavelengths are each at least 900 η

m.