Library merchandise security tag is part of a retail merchandise security system. Attached to the goods, it ensures that in the event of theft either an alarm is triggered or the goods become unusable. Merchandise tags are removed or disabled during the regular payment process.
Mechanical labels often contain a color cartridge. They can only be removed with a special tool or with a considerable amount of time. In the illustrated system, this is usually a built-in strong counter in the counter, which retracts the inner part against the spring force and releases a clamped between the balls holding pin. If they are forcibly broken, the color cartridge is emptied. Textiles are discolored and rendered useless in this way. Mechanical security tags may prevent a repeat theft.
Often, mechanical security tags also include a coil and an RFID chip as a combination of mechanical and electronic security systems. Such mechanical systems are reusable.
An electronic article surveillance tag of an electronic article surveillance system (EAS) triggers an alert as the secured article approaches an antenna. Antenna systems for detection are usually located between the cash register and the outlet of the store to report unpaid goods. Modern merchandise security labels can be activated and deactivated by the cashier.
The trend in retail security is already to integrate the corresponding security elements directly into the product or the product packaging. This so-called source tagging restricts the possibilities of manipulation and reduces the costs for the attachment.
There are currently four different electronic article surveillance systems on the market. These are radio frequency, electromagnetic, high-frequency and acousto-magnetic anti-theft systems.
RF labels have some disadvantages, for example, their size and their low selectivity. Thus, various mobile electronic devices such as hearing aids, radios or mobile phones can coincidentally represent with their electrical circuits resonant circuits on the detection frequency. In these cases, an unwanted false alarm is triggered. Unfavorable orientation relative to the antennas or manipulative metal shielding causes only 70 percent of the active tags to be detected. This speaks against their safety function. By shielding the label no magnetic field gets to the coil and the resonant circuit is no longer excited, so that the label for the detection system is invisible. s
There are also the so-called hard tags. These are conical objects made of plastic, which, fastened with a safety pin, are preferably found on textile goods. Inside them is a coil with a ceramic capacitor between its ends. These labels will be removed and reused after purchase at checkout.
The safety pin apparently makes it impossible for the thief to remove this label. These so-called hard tags are removed at the cash register with a sufficiently strong magnet: by the applied magnet, balls that hold the safety pin by a spring force, withdrawn and release the needle. Thus, this system is only a deceptive security.
The picture on the right shows two labels of the so-called electromagnetic method (EM label). The long metal strip in the upper picture is partially obscured by short strips that have slipped out of position. Below it is embedded in paper and recognizable as light gray shading. The metal strip consists of an easily magnetizable alloy.
In the sinusoidal magnetic alternating field of the control gate with a frequency of 10 Hz to 20 kHz, it comes to saturation. The steep edges of the magnetic reversal generate harmonics in the alternating field, which can be easily detected.