FIELD: measurement equipment.
SUBSTANCE: invention relates to inspection of documents of value with a protective element having low and high coercive magnetic areas, and also combined magnetic areas. After magnetisation of all magnetic areas in the first direction, the second magnetisation is carried out, at which only low coercive magnetic material is magnetised reversely as back-to-back to the first magnetisation, however, high coercive magnetic material remains in the first direction of magnetisation. Then the first magnetic signals of the protective element are detected with the help of the first magnetic detector, and the second magnetic signals of the protective element - with the help of the second magnetic detector. On the basis of the magnetic signals each magnetic area of the protective element is identified as high coercive, low coercive or combined magnetic area.
EFFECT: provision of reliability of differences of each magnetic area.
15 cl, 7 dwg
