Machine-readable security features for printed objects

• US 20050156048A1
• Filed: 11/15/2004
• Published: 07/21/2005
• Est. Priority Date: 08/31/2001
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Reed, Alastair M., Rodriguez, Tony F.
• Granted Patent: US 7,537,170 B2
• Time in Patent Office: Days
• US Class Current: 235/491
• CPC Class Codes: G06T 1/0042 Fragile watermarking, e.g. so as to detect tampering
• CPC Class Codes: H04N 1/00002 Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for error detection, error correction or monitoring in digital computers or digital computer components G06F11/00
• CPC Class Codes: H04N 1/00005 relating to image data
• CPC Class Codes: H04N 1/00037 Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence

Abstract

The present invention provides a security feature that includes a plurality of components. The components may include combinations of time, frequency, space and temperature. In one implementation, a security feature is excited with a particular frequency of light, observed within a certain detection window, and observed at a predetermined angle to allow machine-detection. In another implementation, we provide a machine-readable code that alters with observation of the machine-readable code.

Claims

1. A printed document comprising a machine-readable security feature, the security feature comprising:

a time component;

a frequency component; and

a spatial component.

2. The printed document of claim 1, wherein the time component is conveyed with ink, which when excited provides emissions including a predictable decay rate.

3. The printed document of claim 2, wherein the frequency component comprises at least one of a frequency to excite the ink and a frequency at which the emissions are observable.

4. The printed document of claim 3, wherein the emissions are observable in at least one of the visible, ultraviolet and infrared spectrums.

5. The printed document of claim 3, wherein the spatial component is conveyed through optical variable ink, which includes a first angle of observation providing a first characteristic, with the first characteristic being less observable at a second angle of observation.

6. The printed document of claim 5, wherein the first characteristic comprises at least one of a first color and a first contrast.

7. A printed document including a machine-readable signal comprising:

a first set of print structures conveyed with first ink; and

a second set of print structures convey with optical variable ink,

wherein the second set of print structure are provided to cooperate with the first set of print structures so that at a first observation angle the first set of print structures and the second set of print structures appear to provide a first visibly perceptible feature; and

wherein at a second observation angle the second set of print structures appear less observable so that the first set of print structures and the second set of print structures provide a second visibly perceptible feature.

8. The printed document of claim 7, wherein the first set of print structures and the second set of print structures comprise lines at the first observation angle.

9. The printed document of claim 8, wherein the interrupted print structures comprise breaks in lines.

10. The printed document of claim 9, wherein the breaks are due to the appearance of the optical variable ink at the second observation angle.

11. The printed document of claim 9, wherein the interrupted print structures convey a machine-readable plural-bit auxiliary signal.

12. The printed document of claim 11, wherein the uninterrupted print structures do not convey the plural-bit auxiliary signal.

13. The printed document of claim 7, wherein the printed document comprises at least one of an identification document, check, banknote, product packaging, label and legal document.

14. The printed document of claim 7, wherein the first feature and the second feature are each machine-readable.

15. A printed document comprising:

a first set of elements provided on a surface of the printed document via a first ink, the first ink comprising characteristics which require observation at a first angle and which are less observable at a second angle;

a second set of elements provided on the surface of the printed object via a second ink, the second ink comprising a first emission decay rate, wherein the second ink is excited in a range of non-visible light in order to produce emissions;

wherein the first set of elements and the second set of elements cooperate to convey a machine-readable signal, and wherein the machine-readable signal is only observable at the first observation angle upon excitation in the range of non-visible light.

16. A physical object comprising a substrate and a machine-readable code printed on the substrate, the printed document further comprising a material deposited on or incorporated in the substrate, wherein the material is alterable to change the machine-readable code.

17. The physical object of claim 16, wherein the material is photosensitive and alters with predetermined light excitation.

18. The physical object of claim 17, wherein the material changes at least one of color and color contrast when excited by the predetermined light.

19. The physical object of claim 18, wherein the light comprises at least one of ultraviolet and infrared.

20. The physical object of claim 16, wherein the machine-readable code comprises digital watermarking.

21. A method comprising:

providing a machine-readable code on a physical object; and

providing a mechanism on the physical object so that in response to an observation of the machine-readable code, the mechanism changes the machine-readable code.

22. The method of claim 21, wherein the mechanism comprises at least one of a photosensitive material and a thermochromatic material.

23. The method of claim 21, wherein the observation comprises exposing the physical object to at least one of an ultraviolet and infrared light, and machine-reading the code.

24. The method of claim 23, wherein the machine-readable code is printed on the physical object with ink that emits in response to at least one of infrared and ultraviolet light.

25. The method of claim 21, wherein the physical object comprises at least one of an identification document, check, product packaging, label and banknote.

26. A physical object comprising a machine-readable, steganographic code provided thereon, the physical object comprising a property so that in response to an observation of the code the code is altered to evidence the observation.

27. The physical object of claim 26, wherein the property comprises a photochromatic ink.

28. The physical object of claim 26, wherein the property comprises a photosensitive material.

29. The physical object of claim 26, wherein the property comprises a thermochromatic material.

30. The physical object of claim 26, wherein the machine-readable, steganographic code comprises digital watermarking.

31. The physical object of claim 26, wherein the object comprises a printed document.