Patent ID: 6453061
Filing Date: 2002-09-17
Classification: G07D

Abstract:
A method of controlling banknotes comprising a first print (O) and a second print (I) effected at different stages; the method comprising the steps of:memorizing a reference first image (10) of the first print (O) and a reference second image (11) of the second print (I); acquiring a third image (29) of the banknote (2); calculating absolute deviations (DXO1, DYO3, DXI1, DYI3, DBO12, DB123) of the first print (O) and of the second print (I) in the third image (29) with reference to the first and second images (10, 11); calculating a relative deviation (DXR, DYR, DBR) between the first print (O) and the second print (I) of said banknote (2) as a function of said absolute deviations (DXO1, DYO3, DXI1, DYI3, DBO12, DBI23) of the first print (O) and of the second print (I) in the third image (29); emitting an error signal in the event said relative deviation (DXR, DYR, DBR) fails to fall within a first acceptable range (LR, BR); calculating a deformation (DDR) of the banknote (2) as a function of said absolute deviations (DXO1, DYO3, DXI1, DYI3, DBO12, DBI23) of the first print (O) and of the second print (I) in the third image (29); obtaining modified reference first and second images (10, 11) by applying to said reference first and second images (10, 11) said relative deviation (DXR, DYR, DBR) and said deformation (DDR) of the banknote (2); forming a fourth image (58) of the banknote (2) by combining said modified reference first and second images (10, 11); comparing luminance values of said third image (29) with luminance values of the fourth image (58); and emitting an error signal in the event the luminance values of the third image (29) fail to fall within respective second acceptance ranges (R) of the luminance values of the fourth image (58).