Method for analyzing a fiduciary or security document having a printed graphic and two superimposed security signs and device for carrying out the method

摘要

The invention relates to a method and a device for analysing a document comprising two superposed grids (100, 200), of which one is a periodic watermarked grid and one is a coding by dividing up the printed graphics into parallel bands. According to the invention, sensors are available (300), arranged perpendicularly to the direction of movement of the document, with an interdistance (d) equal to the width (e) of the parallel bands, then the coding of the second grid (200) is checked by adding the responses from each band and from its conjugate, and the first grid (100) is analysed by subtraction of the responses of each non-coded band and of its conjugate. Application to the authentication of a document, especially bank notes. IMAGE