Method of identifying articles
US4195771A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 7, 1978 |
| Grant date | Apr 1, 1980 |
| Priority date | — |
| Expiry date | Dec 7, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/087
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
In the identification of an article provided with at least one identifying magnetic member, each identifying member is selected from one or more production batches each of which has a characteristic hysteresis loop which is virtually non-reproducible. The member is subjected to analysis of its magnetic characteristics which are compared with those of a reference magnetic means comprising the same number of magnetic members from the same batches as the identifying magnetic members. Identical characteristics provide a correct identification. The detection apparatus may comprise two exciter coils for providing two alternating magnetic fields and two detector coils for each field connected in opposition. When an identifying magnetic member inserted in one field is identical to the reference magnetic member inserted in the other field, detection signals from the two detector coils cancel each other out.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.