Permanent magnet assembly for generating concave magnetic field lines and method for producing optical effect coating (reverse rolling bar) having the same

摘要

The present invention relates to the field of protection of security documents such as banknotes and identification documents against counterfeiting and illegal copying. In particular, the present invention relates to a magnetic field generator that generates concave positively curved magnetic field lines. The invention also relates to the use of these magnetic field generators for producing an optical effect layer OEL exhibiting an optical impression of a positive rolling bar effect, for example in the field of document security, and to a method using these magnetic field generators. [Selection] Figure 5b