Monitoring system protecting goods against shoplifting - has label including circuit with PAID and NOT PAID states which are tested by monitoring device

摘要

A label is attached to the goods or their packing, and has an element in which a statement 'not paid' or 'paid' is stored. A cancellation device changes statement 'not paid' into 'paid'. A monitoring device reads the stored statement and delivers a warning signal if the statement is 'not paid'. The cancellation device transmitter emits a changeover frequency which trips a circuit in the label from a first 'not paid' state to the second, 'paid' state. The monitoring device has a test transmitter which detects the label circuit state and emits a warning signal if the state is 'not paid'.