TWI447652B - A radio frequency identification tag with a conductive substrate - Google Patents

Description

Radio frequency identification tag with conductive substrate

The present invention relates to an identification system tag, and more particularly to a radio frequency identification (RFID) tag having a conductive substrate.

Generally, RFID tags are directly attached to products, so they will encounter many problems in use, and the system cannot read the identification data in the RFID tags, for example, product overlap, metal packaging products, content. The product is a liquid product or the like. Therefore, in the research and development of RFID systems, more manpower and R&D expenditures are required.

Because the good conductor can be regarded as a perfect reflecting surface for electromagnetic waves, when the RFID tag is attached to the surface of the metal plate, the antenna near the metal surface cannot effectively receive and emit electromagnetic waves due to the limitation of the boundary condition of the good conductor. The effective reading distance of the system is reduced from a few meters to 1~2 cm, or even completely invalid. In addition, the RFID tags generally used in cartons belong to the dipole antenna structure, so when attached to metal objects, they are affected by the metal conductor mirror current effect and cannot be activated.

The antenna structure for a general carton includes: a meaner antenna, a slot antenna, a folded dipole antenna, an inductively coupled dipole spiral antenna, etc., but these antennas are completely ineffective once attached to the metal, and thus cannot be used on a metal object.

There are two basic strategies for RFID tags to be applied to metal objects: (1) Try to reduce the impact of metal effects, such as: Medium, medium with high-impedance surface structure characteristics; (2) designing metal objects as part of an antenna, such as inverted-F antenna, inverted-F Patch antenna, etc., which has a ground plane structure, When attached to a metal object, the impact is relatively small. Although these antennas can be attached to metal objects, their finished thickness, size, cost and durability are not suitable for mass production applications, especially in applications where metal plate labels are suspended.

Referring to Figure 1, there is shown a schematic diagram of a Radio Frequency Identification System (RFID) tag of U.S. Patent No. 6,914,562. The conventional RFID tag 1 includes a substrate 11, a second conductive tag 12, an RFID device 13, and a radio frequency reflecting structure 14. The conductive tag 12 and the RFID device 13 are disposed on a surface of the substrate 11 , and the RFID device 13 is electrically connected to the conductive tag 12 , wherein the RFID device 13 and the conductive tag 12 have a di-feed Entry points 15, 16. The wireless frequency reflecting structure 14 is disposed on the other surface of the substrate 11. In the conventional RFID tag 1, the radio frequency reflecting structure 14 is a metal plate.

The conventional RFID tag 1 is modified by the position of the conductive tags 12 and the feed points 15, 16 to change their impedance values. The conventional RFID tag 1 is used for being disposed on different package structures or containers, but the readable distance of the conventional RFID tag 1 is not improved.

The conventional RFID tag 1 is suitable for the label of the metal object to be tested and is flat on the surface of the object to be tested. In general practice, in order to avoid the radiation efficiency of the conventional RFID tag 1 being too close to the metal, the substrate 11 (dielectric material) must reach a certain thickness, thereby reducing the interference of the metal test object, otherwise The real part impedance in the Smith Chart diagram (the impedance figure of the complex coordinates) is too small and the electromagnetic waves cannot be effectively transmitted. In addition, it is also stated in the specification of U.S. Patent No. 6,914,562 that the substrate 11 must have a thickness of 3 to 6 mm in the UHF band of 860-950 MHz, so that it has a large overall thickness and a high production cost. (ie more material is required) and its readable distance has not improved.

Therefore, it is necessary to provide an innovative and progressive radio frequency identification tag with a conductive substrate to solve the above problems.

The invention provides a radio frequency identification tag with a conductive substrate, comprising: a conductive substrate and a radio frequency identification device. The conductive substrate has a slot extending through the conductive substrate and having an arrangement section. The radio frequency identification device has a radio frequency identification chip and two conductive strips, and the conductive strips are respectively disposed at two ends of the radio frequency identification chip, and the radio frequency identification chip and the conductive strips are substantially parallel to the set area. Segment settings.

The structure and the production process of the radio frequency identification tag with the conductive substrate of the invention are simple, so the production is easy and the manufacturing cost is low. Moreover, by adjusting the size and shape of the slot or adjusting the characteristics of the RFID device, the radio frequency identification tag with the conductive substrate of the present invention has excellent radiation efficiency, so that the reading distance can be increased. Furthermore, the conductive substrate is used to support and protect the RFID device. Therefore, the RFID tag with the conductive substrate of the present invention has excellent durability and long service life.

Referring to FIG. 2, there is shown a schematic diagram of a radio frequency identification tag having a conductive substrate in accordance with a first embodiment of the present invention. The first implementation of the radio frequency identification tag 2 having a conductive substrate includes a conductive substrate 21, an RFID device 22, and a combining unit 23. The conductive substrate 21 has a slot 211 extending through the conductive substrate 21 and having a setting section 212. The conductive substrate 21 can be a metal substrate, and the conductive substrate 21 is preferably made of copper.

The RFID device 22 has an RFID chip 221, two conductive strips 222, and an antenna structure 223. The conductive strips 222 are respectively disposed at two ends of the RFID chip 221, and the RFID chip 221 and the conductive strips 222 are substantially The setting section 212 is arranged in parallel. The operating frequency of the RFID device 22 can be between 860 MHz and 960 MHz.

The bonding unit 23 is used to combine the RFID device 22 and the conductive substrate 21. Preferably, the bonding unit 23 is an adhesive layer. Furthermore, the combining unit 23 is more usable to protect the RFID device 22. In the embodiment, the RFID device 22 is disposed between the bonding unit 23 and the conductive substrate 21. The antenna structure 223 forms a loop with the RFID chip 221 and the conductive strips 222. The length of the antenna structure 223 is less than the length of the set section 212 and does not overlap the set section 212.

The radio frequency identification tag 2 of the present invention having a conductive substrate can be applied to a windshield of a car, as shown in FIG. The heat insulating paper 25 is attached to the surface of the automobile windshield 24, and the heat insulating paper 25 is equivalent to the conductive substrate 21 in FIG. Therefore, a hole 251 is formed in the heat insulating paper 25, and the RFID device 22 is attached to the heat insulating paper 25, so that the RFID chip 221 and the conductive tape 222 of the RFID device 22 are not covered. To the heat insulating paper 25, that is, the RFID chip 221 and the conductive strips 222 are located at opposite positions of the set portion 252 of the slot 251, thereby exhibiting a radio frequency identification label having a conductive substrate as shown in FIG. 2 effect.

Referring to Figure 4, there is shown a schematic diagram of a radio frequency identification tag having a conductive substrate in accordance with a second embodiment of the present invention. The radio frequency identification tag 3 of the second embodiment having a conductive substrate comprises a conductive substrate 31, an RFID device 32 and a combining unit 33. The radio frequency identification tag 3 having the conductive substrate of the second embodiment is different from the radio frequency identification tag 2 having the conductive substrate of the first embodiment of FIG. 2 in that the combining unit 33 of the second embodiment is overlaid. A portion of the slot 311 of the conductive substrate 31 is provided with a section 312, and the RFID device 32 is fixed to the bonding unit 33 and located in the setting section 312.

Referring to FIG. 5, there is shown a schematic diagram of a radio frequency identification tag having a conductive substrate in accordance with a third embodiment of the present invention. The radio frequency identification tag 4 of the third embodiment having a conductive substrate includes a conductive substrate 41, an RFID device 42, and a combining unit 43. The radio frequency identification tag 4 having the conductive substrate of the third embodiment is different from the radio frequency identification tag 2 having the conductive substrate of the first embodiment of FIG. 2 in that the RFID device 42 in the third embodiment further includes The two extension metal pieces 421 and 422 are electrically connected to the antenna structure 423 of the RFID device 42 respectively, and the extension metal pieces 421 and 422 extend along the setting section 412 of the slot 411 of the conductive substrate 41, respectively. The opposite side edges of the conductive substrate 41 extend, that is, the extended metal piece 421 extends in the upward direction of FIG. 5, and the extended metal piece 422 extends in the downward direction of FIG.

It should be noted that the general RF system antenna is designed to have a 50Ω input impedance to match the impedance of the coaxial line used for the transmission signal. However, in the design of the RFID tag, the input impedance of the antenna structure of the designed RFID device is no longer a simple 50 Ω, but has the impedance characteristics of both the real part and the imaginary part, and the RFID chip has a charging circuit. It has a high Q value (imaginary value > real value), thus increasing the difficulty in designing the RFID tag antenna.

For a radio frequency identification tag with complex impedance characteristics, the impedance of the antenna needs to be designed to be conjugate with the impedance of the RFID chip to achieve impedance matching design requirements to achieve maximum radiation power output. In other words, to increase the effective reading distance of the RFID tag, an effective energy exchange must be performed between the RFID chip and the antenna. When the impedance values of the two reach a complex conjugate match, the efficiency of energy conversion is Can be optimized.

In the present invention, the antenna design technique is used to adjust the size and shape of the slot, or to adjust the characteristics of the antenna structure, so that the antenna structure can be impedance-conjugated with the RFID chip, so that the RFID device can be Directly bonded to the conductive substrate to achieve maximum radiation power output. According to the actual measurement result, the radio frequency identification tag with the conductive substrate of the present invention can effectively read the distance in the air up to 4.0 to 5.0 meters, and has an omnidirectional radiation field shape, and the reading specification can conform to the strip. The actual application needs of the line products.

The structure and the production process of the radio frequency identification tag with the conductive substrate of the invention are simple, so the production is easy and the manufacturing cost is low. And by tune The size, shape, or characteristics of the antenna structure are adjusted. The radio frequency identification tag with the conductive substrate of the present invention has excellent radiation efficiency, so that the reading distance can be increased. Furthermore, the RFID device is coupled to the conductive substrate by using the bonding unit, and the conductive substrate and the bonding unit can be used to support and protect the RFID device. Therefore, the RFID tag with the conductive substrate of the present invention has excellent durability. And a long service life.

The above embodiments are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Therefore, those skilled in the art can make modifications and changes to the above embodiments without departing from the spirit of the invention. The scope of the invention should be as set forth in the appended claims.

1‧‧‧General RFID tags

11‧‧‧ wall panels

12‧‧‧ Conductive label

13‧‧‧RFID device

14‧‧‧Wireless frequency reflection structure

15, 16‧‧‧Feeding points

2‧‧‧ The first embodiment of the present invention has a radio frequency identification tag of a conductive substrate

21‧‧‧Electrical substrate

211‧‧‧ slots

212‧‧‧Setting section

22‧‧‧RFID devices

221‧‧‧RFID chip

222‧‧‧ Conductive tape

223‧‧‧Antenna structure

23‧‧‧Combination unit

24‧‧‧Automobile windshield

25‧‧‧Insulation paper

251‧‧‧Slots

252‧‧‧Setting section

3. The second embodiment of the present invention has a radio frequency identification tag of a conductive substrate

31‧‧‧Electrical substrate

311‧‧‧Slots

312‧‧‧Setting section

32‧‧‧RFID devices

33‧‧‧ combination unit

4 ‧‧ A third embodiment of the present invention has a radio frequency identification tag of a conductive substrate

41‧‧‧Electrical substrate

411‧‧‧Slots

412‧‧‧Setting section

42‧‧‧RFID device

421, 422‧‧‧ extended metal sheets

423‧‧‧Antenna structure

43‧‧‧ combination unit

1 shows a schematic diagram of a radio frequency identification system tag of US Pat. No. 6,914,562; FIG. 2 shows a schematic diagram of a radio frequency identification tag having a conductive substrate according to a first embodiment of the present invention; and FIG. 3 shows a radio frequency identification tag of the present invention having a conductive substrate. FIG. 4 is a schematic diagram showing a radio frequency identification tag having a conductive substrate according to a second embodiment of the present invention; and FIG. 5 is a schematic diagram showing a radio frequency identification tag having a conductive substrate according to a third embodiment of the present invention; .

2‧‧‧ The first embodiment of the present invention has a radio frequency identification tag of a conductive substrate

21‧‧‧Electrical substrate

211‧‧‧ slots

212‧‧‧Setting section

22‧‧‧RFID devices

221‧‧‧RFID chip

222‧‧‧ Conductive tape

223‧‧‧Antenna structure

23‧‧‧Combination unit

Claims (10)

A radio frequency identification (RFID) tag having a conductive substrate, comprising: a conductive substrate having a slot, the slot extending through the conductive substrate and having a setting section; and a radio frequency identification device having a radio frequency identification chip and two conductive strips, the conductive strips are respectively disposed at two ends of the radio frequency identification chip, and the radio frequency identification chip and the conductive strips are substantially parallel to the setting section; wherein the wireless The radio frequency identification device further includes an antenna structure, and the antenna structure forms a loop with the radio frequency identification chip and the conductive strips, and the antenna structure is not part of the conductive substrate. The radio frequency identification tag of claim 1, wherein the conductive substrate is a metal substrate. The radio frequency identification tag of claim 2, wherein the conductive substrate is made of copper. The radio frequency identification tag of claim 1, wherein the length of the antenna structure is less than the length of the setting section, and the setting section is not overlapped. The radio frequency identification tag of claim 1, wherein the radio frequency identification device further comprises two extension metal pieces electrically connected to the antenna structure, and the extension metal pieces are respectively directed toward the conductive substrate along the extending direction of the setting section. The opposite sides extend. The radio frequency identification tag of claim 1, wherein the radio frequency identification device operates at a frequency of 860 MHz to 960 MHz. The radio frequency identification tag of claim 1, further comprising a combining unit for combining the radio frequency identification device and the conductive substrate. The radio frequency identification tag of claim 7, wherein the bonding unit is an adhesive layer. The radio frequency identification tag of claim 7, wherein the radio frequency identification device is disposed between the bonding unit and the conductive substrate. The radio frequency identification tag of claim 7, wherein the combining unit spans at least a portion of the setting section, and the radio frequency identification device is fixed in the combining unit and located in the setting section.