Patent Application
20080150690
1. Field of the Invention
The invention relates to a radio frequency identification tag device, more particularly to a radio frequency identification tag device having a metal substrate.
2. Description of the Related Art
Referring to
The conventional RFID tag device 7 includes an inlay tag 71 packaged by an insulating packing 72 for protection purposes and adhered or hung to the product. The inlay tag 71 has a tag chip 711, and an antenna 712 connected electrically to the tag chip 711.
In operation, the tag reader 8 outputs and transmits a read request signal to the antenna 712 in a wireless manner. Subsequently, after the tag chip 711 receives the read request signal from the tag reader 8 via the antenna 712, the tag chip 711 outputs a reply signal corresponding to the read request signal and indicating product information, such as weight, class, lot number, components, etc, to the tag reader 8 via the antenna 712 in a wireless manner for processing by the system main unit 9.
The conventional RFID tag device 7 is adapted for use with metallic and non-metallic products. In actual use, the conventional RFID tag device 7 for metal products is expensive, has a relatively large size, and receives the read request signal and transmits the reply signal at a frequency of about 2.45 GHz from and to the tag reader 8. As a result, to ensure reception of the read request signal and proper transmission of the reply signal, the conventional RFID tag device 7 is preferably disposed to be spaced apart from the tag reader 8 by a distance not greater than about one meter and to face the tag reader 8 at a specific side thereof, thereby resulting in inconvenience during use. On the other hand, although the conventional RFID tag device 7 for non-metallic products is cheaper than that for metal products, and has opposite sides suitable for transmission and reception at a frequency of about 2.45 GHz, an effective communicating distance between the conventional RFID tag device 7 and the tag reader 8 is relatively short.
If the conventional RFID tag device 7 for non-metallic products is attached to a metallic product to reduce costs, the read request signal radiated by the tag reader 8 is easily reflected by the metallic product. In addition, since a phase difference between the reflected read request signal and the reply signal is 180°, reception of the reply signal by the tag reader 8 may be affected adversely. As a result, the conventional RFID tag device 7 for non-metallic products cannot be directly attached to a metal product.
Furthermore, when the conventional RFID tag device 7 for non-metallic products is installed to a metallic product, such as a steel product, since the packing 72 is relatively fragile as compared to the steel product, collision among the metallic products may result in damage to the conventional RFID tag device 7 during transport.
Therefore, the object of the present invention is to provide a radio frequency identification tag device that is suitable for metallic and non-metallic products and that can overcome the aforesaid drawbacks of the prior art.
According to the present invention, a radio frequency identification tag device comprises:
a metal substrate having opposite first and second surfaces, and a slot that extends from the first surface to the second surface; and
an inlay tag attached to the first surface of the metal substrate and disposed to span at least a part of the slot.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:
Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.
Referring to
The metal substrate 1 has opposite first and second surfaces 101, 102, and a slot 11 that extends from the first surface 101 to the second surface 102. In this embodiment, the slot 11 has an elongate first slot portion 111, and an elongate second slot portion 112 intersecting perpendicularly the first slot portion 111 and having a length shorter than that of the first slot portion 111. The first surface 101 has opposite first and second mounting areas 12, 13 that are disposed respectively adjacent to opposite ends of the second slot portion 112 of the slot 11.
The inlay tag 2 is attached to the first surface 101 of the metal substrate 1, and is disposed to span at least a part of the slot 11. In this embodiment, the inlay tag 2 is a tag designed for non-metallic products and to operate at an operating frequency of 2.45 GHz, and includes a dipole antenna 22 and a tag chip 21. The antenna 22 has opposite first and second end portions 221, 222 attached respectively to the first and second mounting areas 12, 13 of the first surface 101 of the metal substrate 1, and a meandering intermediate portion 223 interconnecting the first and second end portions 221, 222 and disposed to span the second slot portion 112 of the slot 11 in the metal substrate 1. The tag chip 21 is connected electrically to a center of the intermediate portion 223 of the antenna 22, and has an impedance matching that of an assembly of the dipole antenna 22 and the metal substrate 1.
In this embodiment, the label sheet 4 is made from a non-metallic material, such as paper, and covers the first surface 101 of the metal substrate 1 and the inlay tag 2. The label sheet 4 is formed with visible product information in the form of a bar code 41.
It is noted that the RFID tag device of this invention can be installed to metallic and non-metallic products. Regardless of whether the RFID tag device of this invention is installed to a metallic product or a non-metallic product, one of the first and second surfaces 101, 102 of the metal substrate 1 is adapted to face a tag reader (not shown) during use, and an effective communication distance between the RFID tag device of this invention and the tag reader can be increased up to 1.68 meters for a transmission frequency of about 2.45 GHz. Furthermore, due to the presence of the metal substrate 1, the RFID tag device of this invention has an adequate strength to protect the inlay tag 2.
While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
