| 摘要 |
<p>An apparatus is disclosed which enables electronic article security tags to be deactivated in bulk by demagnetisation. An open ended housing which can be retro-fitted to a conveyor along which tagged articles in bulk are travelling in boxes with the tags randomly oriented has side portions accommodating series- connected first and second coils and a third coil is accommodated in the top of the housing. The two sets of coils, namely the first and second coils generating a predominantly horizontal magnetic field and the third coil generating a predominantly vertical magnetic field, each have associated capacitor charging and discharging circuits controlled in dependence of box detectors located at the approach to the housing and within the housing, the capacitor discharging circuits developing an oscillatory decaying current through the respective coil(s) such as to demagnetise the tags as they pass through on the conveyor, it being ensured that the two capacitor discharges are separated in time so that there is no significant interaction between the horizontal and vertical fields. Also described is a modification which enables the coils to selectively generate magnetising fields.</p> |
