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Introduction to Retail RFID Technology, part 3 - Tags

The third part of the article series Introduction to RFID technology takes a look at different types of tags. Tags are an essential part of an RFID system as they are used as an identifier for the product.

We have previously exhibited some RFID basics in the first part of the article. In the second part we discussed radio technology and radio waves.

Different types of tags

A tag can come in various forms, depending on its purpose of use and the frequency of the system. 

There are three types of tags. Active and semi-passive tags have an own power source and they are often used in ports and harbors where long reading distances are needed. Tags reporting temperature, which are used in the horticultural, healthcare and grocery industry, also have their own power source. The tags used in apparel are passive, which means that they do not have their own power source. Instead, they take all the needed energy from the reader through radio waves. Whether the tag has its own power source or not also sets limits to the reading distance, which varies from 10mm to 8m depending on the reader in use and on the position of the tag. A passive tag is rather cheap to produce, which is a great benefit for the apparel industry, especially if the tags are not recyclable. In addition, there are no remarkable differences in performance between these tags. In addition to providing a product with a unique identity, a tag can have other functions as well. A tag can i.eg be used for reporting temperature as mentioned above, or for reporting humidity, orientation or pressure.

Tags -soft -and -hard

EPCglobal (under GS1) has actively driven RFID standards for tags. With the Gen-2 standard, EPCglobal managed to create a single marketplace for UHF RFID systems and opened the world to compatible and interoperable readers and tags. EPCglobal classifies which protocol is used when a tag and a reader communicate. The second-generation system of classification, Gen-2, is designed for global operations. The basic idea of Gen-2 was that products built according to the Gen-2 standard would work with each other in any part of the world. The major regional regulatory environments are taken into account in the way the standard defines how the tags and readers use frequency and power. In addition, Gen-2 provides increased speed for reading and writing tags for supply chain operations, as well as the ability to function also in dense reader environments such as in distribution centers, warehouses and such. (Brown 2007) 

Tag selection criteria

There is a wide range of tags used for apparel. Typically the tags in apparel are divided into two groups: soft tags and hard tags. Some of them are smart labels - stickers on which the price information is printed. Some are hard smart pins which are used as the counter-element of an electronic alarm, and some can be sewn into the garment in the production phase and will perhaps never be noticed by the consumer who purchases the garment. 

What is typical for all the UHF tags is the structure. Each tag has a chip and a dipole antenna as can be seen in the smart label tag inlay below. The chip which includes the product information is in the center of the tag. The antenna which assists in communication with the reader is horizontally in both sides of the chip. 

Rafsec Gen 2 Short Dipoli

An example of a tag inlay by Smartrac

Another subject of discussion regarding tags is whether they are reusable or not. Generally, smart labels and tags placed on the products in the production phase which will remain there (for instance a thin tag inside the side seams) cannot be reused. Smart pin tags, on the contrary, can be removed from the garment they have been attached to and be placed on a new item. This needs of course changing the tag information in the back end system, but with the systems that exist today that's not a trick to do. The other benefit of the smart pin tag is the fact that the counter-part of the pin is an EAS alarm. Therefore, smart pins are very suitable for piloting in a store which uses an EAS system with normal pins.

Practical tips for retailers

GS1 US-VICS has created guidelines for tag placement in apparel retail. The manual provides wide instructions about where the tag should hang in jeans, t-shirts, underwear and accessories, for instance. The manual uses the current UPC tag placement guideline as a starting point. Basically, the EPC should be placed on media, trim, or packaging attached to the physical garment itself so that the customer can remove it after purchase. Alternatively, the tag can be separately affixed close to the UPC. However, all the products in the same category or merchandise do not necessarily have the same placement in men's, women's and children's apparel. To reach optimal readability, there are five certain placement options that should be avoided. Do not put the tag:

  • in places where the EPC tag to the place where the hanger clips might go (the hanger clips may reduce readability)
  • in places that are in contact with metal
  • in places where the EPC tag might get folded
  • directly onto to hanger
  • loosely inside a package. 

These kinds of guidelines help retailers to plan their tagging processes so that the results of using the tags would be the maximum.

The fourth article of this series discusses the readers and antennas. One more article to follow…

References

Brown, Dennis E. (2007) RFID Implementation. McGraw-Hill Communications.

VICS: Addendum to GS1 Apparel Guidelines: Format and Symbol Placement regarding Electronic Product Code (EPC) Placement, September 2011

1 comment on “Introduction to Retail RFID Technology, part 3 - Tags”

  1. Posted 09 January 2017 at 08:55:20

    Good quality products are always a great thing for all the communities because in this way the society becomes great.
    Thanks

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