EP 0848356 A1 19980617 - Substrate comprising magnetic particles, security document and method for detecting them
Title (en)
Substrate comprising magnetic particles, security document and method for detecting them
Title (de)
Substrat enthaltend magnetische Partikeln, Sicherheitsdokument und Verfahren zu deren Detektion
Title (fr)
Substrat comprenant des particles magnétiques, documents de sécurité et procédé de leur détection
Publication
Application
Priority
EP 96402721 A 19961212
Abstract (en)
A method for detecting the presence of magnetic particles in a substrate the base material of which has magnetic properties substantially differing from the corresponding magnetic properties of the particles. The_particles have such a long and thin form that their demagnetisation factor N is smaller than 1250, they have a diameter smaller than 30 micrometer and a magnetic saturation field ranging from 100 to 1000 A/m. The method comprising following steps : (a) emitting an electromagnetic source signal of one or more particular base frequencies to said substrate so that any present magnetic particles go into a non-linear part of their B-H curve for at least part of a cycle of the source signal ; (b) detecting an electromagnetic detection signal emanating from said substrate ; (c) testing the detection signal for the presence of particular higher harmonics of said base frequencies or of any linear combination of said base frequencies, said particular higher harmonics being indicative of the presence of said magnetic particles. <IMAGE>
IPC 1-7
IPC 8 full level
CPC (source: EP US)
Citation (applicant)
- US 4114032 A 19780912 - BROSOW JORGEN, et al
- US 4218674 A 19800819 - BROSOW JORGEN [AU], et al
- EP 0625766 A2 19941123 - NHK SPRING CO LTD [JP]
- EP 0632398 A2 19950104 - NHK SPRING CO LTD [JP]
- EP 0656607 A2 19950607 - NHK SPRING CO LTD [JP]
- FR 2425937 A1 19791214 - ARJOMARI PRIOUX [FR]
- US 4820912 A 19890411 - SAMYN JOHAN [BE]
- WO 9524000 A1 19950908 - BEKAERT SA NV [BE]
- US 3313941 A 19670411 - MARKS MORTIMER M
- US 3449585 A 19690610 - TREHUB ARNOLD
- FR 763681 A 19340504
- US 3631442 A 19711228 - FEARON ROBERT E
- US 3990065 A 19761102 - PURINTON EDWIN C, et al
- EP 0153286 A2 19850828 - INTERMODULATION & SAFETY SYST [SE]
- EP 0295028 A1 19881214 - SCIENT GENERICS LTD [GB]
- US 4298262 A 19811103 - NOZAWA HIDEYO, et al
- FR 9502868 A 19950313
- FR 960390 W
Citation (search report)
- [A] DE 2635795 A1 19770317 - DASY INT SA
- [AD] US 4114032 A 19780912 - BROSOW JORGEN, et al
- [AD] EP 0656607 A2 19950607 - NHK SPRING CO LTD [JP]
- [AD] EP 0632398 A2 19950104 - NHK SPRING CO LTD [JP]
- [AD] EP 0625766 A2 19941123 - NHK SPRING CO LTD [JP]
- [AD] WO 9524000 A1 19950908 - BEKAERT SA NV [BE]
Designated contracting state (EPC)
AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
DOCDB simple family (application)
EP 96402721 A 19961212; AR P970105815 A 19971211