Method and apparatus for checking the authenticity of documents

[54] METHOD AND APPARATUS FOR

CHECKING THE AUTHENTICITY OF
DOCUMENTS

[75] Inventor: Johan Samyn, Roeselare, Belgium

[73] Assignee: N. V. Bekaert S.A., Zwevegem, Belgium

[21] Appl. No.: 910,153

[22] Filed: Sep. 19,1986

[30] Foreign Application Priority Data

Sep. 19, 1985 [NL] Netherlands 8502567

[51] Int. a* G01R 27/04

[52] U.S. CI 235/449; 235/482;

235/492; 324/58 A; 340/825.34; 283/70;

283/83

[58] Field of Search 340/825.34, 825.35;

235/380, 435, 449, 487, 492, 491, 475, 480, 482; 283/70, 72, 74, 83; 324/58.5 R, 58.5 A, 58.5 B,

58 R, 58 A, 58 B

[56] References Cited

U.S. PATENT DOCUMENTS 4,255,652 3/1981 Weber 235/492

4,310,591 1/1982 Lee et al 283/74

4,584,529 4/1986 Aoyamo 235/449

4,630,845 12/1986 Sannee 340/825.34

4,656,474 4/1987 Mollier et al 340/825.34

4,729,128 3/1988 Grimes et al 235/380

Primary Examiner—A. D. Pellinen

Assistant Examiner—Jeffrey A. Gall

Attorney, Agent, or Firm—Foley & Lardner, Schwartz,

Jeffery, Schwaab, Mack, Blumenthal & Evans

[57] ABSTRACT

A method and an apparatus for checking the authenticity of documents, such as banknotes or credit-cards. The documents comprise a number of randomly distributed conductive fibres of which the distribution is scanned by microwaves and the response is transformed into a digital coded signal. A digital mark on the document, which is representative for the distribution of an individual document, is read off, transcoded, and compared with said coded signal for producing an approval signal. The use of a microwave scanning system in conjunction with documents having a random distribution of suitable fibres ensures a great repetitivity and security of the system.

11 Claims, 3 Drawing Sheets