Working principle of electronic label
The basic working principle of RFID technology is not complex: after the tag enters the magnetic field, it receives the RF signal sent by the interpreter, sends the product information stored in the chip (passive tag, passive tag or passive tag) with the energy obtained by the induced current, or actively sends the signal of a certain frequency (activetag, active tag or active tag); The interpreter reads and decodes the information and sends it to the central information system for relevant data processing.
RFID (radio frequency identification) system consists of two parts: read / write unit and electronic transceiver. The reader sends electromagnetic pulses through the antenna, and the transceiver receives these pulses and sends the stored information to the reader in response. In fact, this is the non-contact reading, writing or deletion of the data in the memory.
Technically, the “smart tag” includes an RFID circuit including an RFID chip with an RFID RF part and an ultra-thin antenna loop, which is embedded in the tag together with a plastic sheet. Usually, a paper label is pasted on this label, and some important information can be clearly printed on the paper label. At present, smart tags are generally the size of credit cards, and there are 4.5 for small goods × 4.5cm size labels, as well as 4.7cm diameter circular labels used on CDs and DVDs.
Compared with other ID technologies such as bar code or magnetic stripe, the advantage of transceiver technology lies in the wireless link between reader and transceiver: the read / write unit does not need visual contact with the transceiver, so it can be fully integrated into the product. This means that the transceiver is suitable for harsh environments and is not sensitive to moisture, dirt and mechanical effects. Therefore, the transceiver system has very high read reliability and fast data acquisition. The last and important point is to save labor and paper.
What are the technical parameters of electronic labels
The technical parameters of electronic tags mainly include the energy requirements of tag activation, the reading and writing speed of tag information, the transmission rate of tag information, the capacity of tag information, the packaging size of tag, the reading and writing distance of tag, the reliability of tag, the working frequency of tag and the price of tag.
1. Energy requirements for label activation
When the electronic tag enters the working area of the reader, it is excited by the RF signal sent by the reader, and the tag enters the working state. The activation energy of the tag refers to the energy range required to activate the chip circuit of the electronic tag, which requires that the electronic tag is within a certain distance from the reader, and the reader can provide sufficient RF field strength of the electronic tag.
2. Reading and writing speed of label information
The reading and writing speed of the tag includes reading speed and writing speed. The reading speed refers to the speed at which the electronic tag is read by the reader and writer, and the writing speed refers to the writing speed of the electronic tag information. Generally, the reading and writing of the tag information is required to be in milliseconds.
3. Package size of label
The package size of the label mainly depends on the size of the antenna and power supply. There are different requirements for the package size in different occasions. The small package size is millimeter level and the large one is decimeter level.
If the size of the electronic tag is small, it has a wide range of application. It can be set for both large and small items. However, it is not good to blindly pursue small size. If the design of electronic tag is relatively large, the size of antenna can be increased, so it can effectively improve the reading rate of electronic tag.
4. Capacity of label information
The capacity of tag information refers to the amount of memory carried by the electronic tag for writing data. The capacity of label information is related to whether the electronic label is “foreground” or “background”.
(1) “Background” electronic label
After the “background” electronic tag collects data through the reader and writer, it can be connected with the computer database through the network. Therefore, generally speaking, as long as the memory of the electronic tag has more than 200 bits, it can accommodate the coding of items. If you need more detailed information about the item, this electronic label needs to be provided through the background database.
(2) “Front desk” electronic label
In practical application, it is sometimes difficult to connect the database on site, so it is necessary to increase the memory of the electronic tag, such as thousands to tens of thousands, so that the electronic tag can be used independently without checking the database information. This electronic tag can be called “foreground” electronic tag. However, when selecting the “front desk” electronic tag, it should be noted that generally speaking, the larger the memory, the longer the reading time. This electronic tag can be used only when those time factors are not very important, but the more detailed information of the item must be known at that time.
5. Alignment distance of labels
The reading and writing distance of the tag refers to the working distance between the tag and the reader. The reading and writing distance of the label is mm near and more than 20m far. In addition, the read distance and write distance of most systems are different, and the write distance is about 40% ~ 80% of the read distance.
6. Transmission rate of label information
The transmission rate of tag information includes two aspects: one is the transmission rate of data fed back by the electronic tag to the reader and the other is the rate of data written from the reader.
7. Operating frequency of label
The working frequency of the label refers to the frequency used when the label works, which can be low frequency, high frequency, UHF and microwave.
8. Reliability of labels
The reliability of the tag is related to the working environment, size, material, quality, distance between the tag and the reader. For example, on a conveyor belt, when the label is exposed and read individually, the reading accuracy is close to 100%. However, many factors may reduce the reliability of label reading and writing. The more labels read at the same time, the faster the label moves, and the more likely it is to be misread or missed.
The survey in the application of a project shows that when 10000 electronic labels are used, 60 electronic labels are damaged in a year, and the proportion of damage is less than 0.1%. In order to prevent the inconvenience caused by the damage of electronic labels, the simultaneous use of bar codes and electronic labels is an effective remedy, so that an electronic label can be quickly copied according to the information recorded in bar codes. In addition, putting two electronic labels on an item in case is also a method, but it will make the cost of the whole project higher.
9. Price of label
At present, the price of a large order of some electronic labels is less than 1 yuan. When the number of electronic labels is 1 billion, the economies of scale will greatly reduce the price of electronic labels. Many companies hope that each electronic label will be less than 0.4 yuan in the future. The price of smart electronic labels is high, generally more than 10 yuan.
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