| 摘要 |
An article 1, for use with a detection system 31, has embedded within it a marker 2, particularly a magnetic tag, which can be detected by the detection system 31. The detection system 31 includes a transmitter having a frequency generator 33, an amplifier 34 and a transmitting coil 35 to generate a magnetic field within an interrogation zone and a receiver having a receiving coil 36, a receiver 37 and an alarm unit 38 which is energizable upon an article 1 having a marker 2 embedded therein being detected within the interrogation zone 32. Being embedded within the article, the marker is not easily removed and the envisaged articles include sheets of paper, tape cartridges (Fig 8) and food trays (Fig 9). The tag may be a strip of magnetic material introduced prior to baking of paper sheets (Fig 5) or may be laminated between sheets (Fig 6). The detection system may be associated with the power line to a copier (Fig 4) to prevent copying. <IMAGE> |
