What Is One-bit Electronic Tag?

What Is One-bit Electronic Tag?

 

One-bit Electronic Tag

 

The data volume of a one-bit system is one bit. When an electronic tag is a one-bit (1b) system, the electronic tag has only two states: 1 and 0. The reader/writer of this system can only output two states, which are "electronic tag in the reader/writer working area" and "no electronic tag in the reader/writer working area." The one-bit electronic tag is the earliest commercially used electronic tag, which first appeared in the 1960s. It is mainly used in the Electronic Article Surveillance (EAS) system in stores. The reader/writer of this system is usually placed at the store entrance, and the electronic tag is attached to the merchandise. When the merchandise passes through the store entrance, the system alarms.

 

The one-bit electronic tag does not require a chip and can work using various methods such as radio frequency (RF), microwave, frequency division, smart type, electromagnetic, and acousto-magnetic methods. The working principle of a one-bit electronic tag is introduced below, taking the RF method as an example.

 

Working Principle of the Radio Frequency Method

 

The RF working system consists of three parts: the reader/writer (detector), the electronic tag, and the deactivator. The electronic tag uses an L-C oscillating circuit to work, and the oscillating circuit tunes the frequency to a certain resonant frequency fR. The RF working system reader/writer (detector) emits an alternating magnetic field with a certain frequency fG. When the frequency of the alternating magnetic field fG is the same as the resonant frequency fR of the electronic tag, the oscillating circuit of the electronic tag generates resonance. At the same time, the current in the oscillating circuit counteracts the external alternating magnetic field, leading to a reduction in the amplitude of the alternating magnetic field. If the reader/writer (detector) detects a reduction in the alternating magnetic field, it will alarm. After the electronic tag has been used, it is destroyed using a "deactivator." The working principle of the RF method is shown in Figure 5-2.

 

 

(1) Reader/Writer (Detector). A reader/writer (detector) generally consists of two parts: a transmitter and a receiver. Its basic principle is to use the transmitting antenna to emit an alternating magnetic field, forming a scanning area between the transmitting and receiving antennas, and to use the receiving antenna to receive this alternating magnetic field within its receiving range. The RF working system uses the principle of electromagnetic wave resonance to search whether an electronic tag exists in a specific range. If an electronic tag appears in this area, an alarm is triggered immediately.

 

(2) Electronic Tag. The interior of the electronic tag is an L-C structured oscillating circuit, and the electronic tag is installed on the merchandise in a special way. Electronic tags currently on the market include soft tags and hard tags.

 

The deactivator can generate a sufficient magnetic field, which can destroy the thin-film capacitor in the electronic tag, causing the L-C structure inside the electronic tag to fail.

 

Deactivators are often replaced by unlockers or decoders. Unlockers are devices used to quickly remove various hard tags. Decoders are devices that disable soft tags. The non-contact decoders commonly used on the market today can decode a soft tag simply by passing it within 20 cm above the decoder.

 

Introduction to Electronic Article Surveillance (EAS) System

 

Today, the application of the Electronic Article Surveillance (EAS) system in retail business is becoming increasingly widespread. It is an electronic anti-theft product that reduces merchandise theft during open-shelf sales, thereby increasing sales profit, and is one of the security measures widely adopted by the current large-scale retail industry. In fact, the EAS system is a simple radio frequency identification system. Since it has only two states, it can only indicate the presence or absence of the merchandise, not what the merchandise is. The steps for EAS system theft detection are as follows.

 

(1) The anti-theft tag is attached to the merchandise.

(2) Detectors are installed at the store exit aisle or the cashier aisle.

(3) After payment, the merchandise passes through a dedicated decoder to disable the tag or uses an un-locker to remove the tag.

(4) When unpaid merchandise (with the attached tag) passes through the exit, the doorway detector detects the tag and issues an alarm, intercepting the merchandise from leaving.

 

Electronic tags are divided into soft tags and hard tags. Soft tags have a lower cost and are directly attached to "harder" merchandise. Soft tags cannot be reused. Hard tags have a higher one-time cost than soft tags but can be reused. Hard tags must be equipped with a specialized detacher and are mostly used for soft, easily penetrated items like clothing.

 

Decoders are mostly non-contact devices with a certain decoding height. When the cashier checks out or bags the items, the electronic tag can be decoded without touching the degaussing area. If merchandise leaves the store without being decoded, the detector will trigger an alarm, reminding the cashier, customer, and store security personnel to handle it promptly.

 

The Electronic Article Surveillance (EAS) system does not cause customers to feel uncomfortable like surveillance systems and also serves as a deterrent. There are four main technologies in the EAS system: radio frequency, electromagnetic, microwave, and acousto-magnetic technologies. Generally, electromagnetic and RF products are cheaper, and their tags are usually permanently adhered to the merchandise or packaging, while microwave and acousto-magnetic tags are more expensive.