| 摘要 |
A method and an apparatus and system are disclosed for activating, deactivating or reactivating an electronic article surveillance (EAS) label by way of a coil antenna in an H-bridge circuit which generates from the antenna: a positive increasing magnetic field; a positive decreasing magnetic field; a negative increasing magnetic field; and a negative decreasing magnetic field. The positive and negative magnetic fields are created by positive and negative currents directed through the antenna by four switches connected to the antenna in an H-bridge configuration. The method and apparatus enable low voltage activation, deactivation or reactivation of an EAS tag, e.g., at voltage levels of 12 to 24VDC, ensure uninterruptible power in case of loss of external power, and portability without a high voltage capacitor which is normally required in large deactivation designs. Activation and reactivation is by an increasing magnetic field followed by a decreasing magnetic field without altering polarity.
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