Record document authentication by microscopic grain structure and method

• US 5,325,167 A
• Filed: 05/11/1992
• Issued: 06/28/1994
• Est. Priority Date: 05/11/1992
• Status: Expired due to Term

• Current Assignee: Canon Inc.
• Original Assignee: Canon Research Center America Inc (Canon Inc.)
• Inventors: Melen, Roger D.
• Primary Examiner(s): Warden, Robert J.
• Assistant Examiner(s): CRAWFORD, LESLIE
• Application Number:
  US07/881,065
• Time in Patent Office: 778 Days
• Field of Search: 356/71, 235/380, 235/382, 235/468, 235/469, 235/494, 340/825.34
• US Class Current: 356/71
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06K 19/14 the marking being sensed by radiation
• CPC Class Codes: G06V 20/80 Recognising image objects characterised by unique random patterns
• 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

Record document may be authenticated against reference grain data obtained from the document at a prior time. The body of the document is formed by base medium bearing the record entries such as text within record site. Grain seal site is located at a predetermined location within the base medium. The unique grain structure within the seal site are microscopic and function as a seal for authenticating the document. The seal site is initially scanned to provide a stream of reference data generated by the surface reflection of the grain structure. This reference grain data is stored in memory for future authentication use. The seal site is then currently scanned to generate a stream of current grain data for comparison to the reference grain data.

Claims

1. A document bearing record entries, which document may be currently authenticated against reference grain data obtained from the document during a reference scan made at a prior timer, comprising:

base medium forming the document;

grain seal site having a visible shape at a predetermined location within the base medium;

unique microscopic grain structure formed by opaque toner particles having reflective facets deposited on the surface of the base medium after manufacture thereof and bonded to the base medium within the seal site, which grain structure may be scanned to provide current grain data for comparison to reference grain data obtained from the document during a reference scan made at a prior time.

2. The document of claim 1, wherein the visible shape of the grain seal site formed by the deposited toner grain structure is round.

3. The document of claim 1, wherein the visible shape of the grain seal site formed by the deposited toner is a symbol.

4. The document of claim 1, wherein the toner particles contain a sealant material which forms a protective cover over each of the individual toner particles in the grain seal site.

5. The document of claim 4, wherein the sealing material forms a sealing film over the grain seal site for protecting the grain seal site.

6. The document of claim 1, wherein the toner particles are deposited in amounts sufficient to fully cover the grain seal site forming an opaque layer of toner particles without any exposed base medium within the grain seal site.

7. The document of claim 1, wherein the toner particles are deposited in amounts sufficient only to partially cover the grain seal site forming broken a layer of toner particles with regions of exposed base medium within the grain seal site.

8. The document of claim 7, wherein the unique grain structure is formed by the optical contrast between toner grain structure provided by the deposited toner and exposed inherent grain structure provided by the regions of exposed base medium within the grain seal site.

9. The document of claim 1, wherein the base medium has a record side containing record entries, and an opposite side thereto, and the grain seal site is on the surface of the record side of the base medium along with the record entries.

10. The document of claim 1, wherein the base medium has a record side containing record entries, and an opposite side thereto, and the grain seal site is on the surface of the opposite side of the base medium from the record entries.

11. The document of claim 1, wherein wherein the base medium has a record side containing record entries, and an opposite side thereto, and a digital data site on the surface of the record side of the base medium along with the record entries.

12. The document of claim 1, wherein the base medium has a record side containing record entries, and an opposite side thereto, and a digital data site on the surface of the opposite side of the base medium from the record entries.

13. A method of authenticating a document bearing record entries, comprising the steps of:

providing a document bearing record entries having a unique microscopic grain structure thereon formed by opaque toner particles having reflective facets deposited on the surface of the document and bonded to the document within a grain seal site on the document;

initially scanning the unique microscopic grain structure within the grain seal site on the document with an initial scanning means at an initial time to form a stream of initial data pixels in response to the unique microscopic grain structure;

entering the initial data pixels into an initial memory means;

subsequently scanning the unique microscopic grain structure within the grain seal site on the document with a subsequent scanning means at a subsequent time to form a stream of subsequent data pixels in response to the grain structure;

entering the subsequent data pixels into a subsequent memory means;

comparing the initial data pixels to the subsequent data pixels to determine if a grain correlation exits indicating that the subsequently scanned document is the same document as the initially scanned document.

14. The method of claim 13, wherein the seal site has macroscopic features therein in addition to the microscopic grain structure.

15. The method of claim 14, further comprising the additional step of:

filtering the subsequent data pixels before the comparing step to eliminate large variations therein corresponding to the macroscopic features in the seal site at the subsequent time.

16. The method of claim 15, further comprising the additional step of:

filtering the initial data pixels before the comparing step to eliminate large variations therein corresponding to the macroscopic features in the seal site at the initial time.

17. The method of claim 16, wherein the filtering step is standard deviation filtering further comprising the steps of:

determining the standard deviation of the variations in the initial data and in the subsequent data;

removing any signals in the initial data and in the subsequent data which exceed a predetermined Nth standard deviation.

18. The method of claim 17, wherein N=3.

19. The method of claim 13, wherein the initial data and the subsequent data each have a variable component and a steady component, and during the comparing step only the variable component of the initial data and the variable component of the subsequent data are compared.

20. The method of claim 19, wherein during the entering steps only the variable component of the initial data and the subsequent data are entered into the memory means.

21. The method of claim 20, wherein during the scanning steps only the variable component of the initial data and the subsequent data are scanned into the stream of initial data and the stream of subsequent data.

22. The method of claim 13, further comprising the additional steps of:

low pass filtering the stream of initial data prior to entering into the initial memory to eliminate signal components above a predetermined pass frequency; and

low pass filtering the stream of subsequent data prior to entering into the subsequent memory to eliminate signal components above a predetermined pass frequency.

23. The method of claim 13, comprising the additional step of depositing toner particles on the document within the grain seal site prior to the providing a document step and the initially scanning step to provide microscopic grain structure.

24. The method of claim 23, wherein the document has a record side containing record entries, and an opposite side thereto, and the grain seal site is on the opposite side of the document from the record entries.

25. The method of claim 23, comprising the additional steps of:

retrieving the initial data from the initial memory means; and

printing the retrieved initial data in digital form onto the document.

26. The method of claim 25, wherein the toner particles are deposited on the document within the grain seal site during the printing of the record entries onto the document.

27. The method of claim 13, wherein the initially scanning step and the subsequently scanning step each comprise the additional steps of:

providing a source of scanning photons;

reflecting the scanning photons off of the grain structure within the grain seal site; and

detecting the reflected scanning photons to provide stream of initial data and the stream of subsequent data.

28. The method of claim 13, further comprising the step of:

determining a correlation coefficient after the comparison step indicating the extent of matching between the initial data and the subsequent data wherein the correlation coefficient CC is;

space="preserve" listing-type="equation">CC=M/T

where

M is the number of matched pixels, and

T is the total number of pixels compared.

29. A method of authenticating a document bearing record entries and having pre-existing unique microscopic grain structure within a seal site, comprising:

providing a base medium forming a document with toner particles deposited thereon defining a seal site with a unique microscopic grain structure formed by opaque toner particles having reflective facets deposited on the surface of the base medium and bonded to the base medium;

printing record entries onto the base medium;

initially scanning the grain structure within the seal site on the base medium to form an initial data stream of seal site data in response to the grain structure;

entering the initial data stream of seal site data into an initial memory means;

subsequently scanning the grain structure within the seal site on the document to form a subsequent data stream of seal site data in response to the grain structure;

entering the subsequent data stream of seal site data into a subsequent memory means;

comparing the initial seal site data to the subsequent seal site data to determine if a grain correlation exits indicating that the initially scanned document is the same document as the subsequently scanned document.

30. The method of claim 29, wherein the initial memory means for receiving the initial data stream of seal site data is an off-document memory.

31. The method of claim 29, wherein the initial memory means for receiving the initial data stream of seal site data is an on-document companion memory formed by a digital data site on the base medium.

32. The method of claim 29, wherein the initial memory means for receiving the initial data stream of seal site data is an off-document memory and also an on-document companion memory formed by a digital data site on the base medium.

33. The method of claim 29, wherein the during the step of initially scanning, the record entries are also scanned and converted into digital data, and during the entering the initial data stream step both the seal site data and the record entries data are entered into the initial memory means.

34. A method of authenticating document bearing record entries by generating unique microscopic grain structure within a seal site, comprising:

providing a base medium forming a document;

printing record entries onto the base medium;

depositing opaque toner particles having reflective facets on the surface of the base medium and bonding the toner particles to the base medium within a seal site for providing a unique microscopic grain structure;

initially scanning the grain structure within the seal site on the base medium to form an initial data stream of seal site data in response to the grain structure;

entering the initial data stream of seal site data into an initial memory means;

subsequently scanning the grain structure within the seal site on the document to form a subsequent data stream of seal site data in response to the grain structure;

entering the subsequent data stream of seal site data into a subsequent memory means;

comparing the initial seal site data to the subsequent seal site data to determine if a grain correlation exits indicating that the initially scanned document is the same document as the subsequently scanned document.

35. The method of claim 34, wherein the step of printing the record entries and the step of depositing the toner particles are a single step.

36. The method of claim 34, wherein the initial memory means for receiving the initial data stream of seal site data is an off-document memory.

37. The method of claim 34, wherein the initial memory means for receiving the initial data stream of seal site data is an on-document companion memory formed by a digital data site on the base medium.

38. The method of claim 34, wherein the initial memory means for receiving the initial data stream of seal site data is an off-document memory and also an on-document companion memory formed by a digital data site on the base medium.

39. The method of claim 34, wherein the during the step of initially scanning, the record entries are also scanned and converted into digital data, and during the step of entering the initial data stream both the seal site data and the record entries data are entered into the initial memory means.