TWI463411B - 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 the antenna, such as inverted-F antenna, inverted-F Patch antenna, etc., which have a ground plane structure, so attach When it comes to metal objects, 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 (RFID) tag with a conductive substrate, comprising: a conductive substrate, a radio frequency identification device and a combining unit. The conductive substrate has a slot, and the slot defines a notch on one side of the conductive substrate, and the slot penetrates the conductive substrate. The radio frequency identification device has a radio frequency identification chip and two conductive strips respectively disposed at two ends of the radio frequency identification chip, and the radio frequency identification chip and the conductive strips are disposed in the slot. The bonding unit combines the radio frequency identification device and the conductive substrate.

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 antenna structure, 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 the bonding unit, and the conductive substrate and the bonding unit can also be used to support and protect the RFID device. The RFID device, therefore, the RFID tag with the conductive substrate of the present invention has excellent durability and a 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. The slot 211 extends through the conductive substrate 21, and a notch 212 is formed on one side of the conductive substrate 21. The conductive substrate 21 can be a metal substrate, and the conductive substrate 21 is preferably made of copper.

In this embodiment, the RFID device 22 has an RFID chip 221, two conductive strips 222 and 223, and an antenna structure 224. The RFID chip 221, the conductive strips 222 and 223, and the antenna structure 224 are disposed in the slot. 211. The conductive strips 222 and 223 are respectively disposed at the two ends of the RFID chip 221, and the antenna structure 224 forms a loop structure with the RFID chip 221 and the conductive strips 222 and 223, that is, the antenna structure of the embodiment. The 224 is a small loop antenna. In other applications, the antenna structure 224 can also be a dipole antenna or a monopole antenna. Wherein, the RFID device 22 can operate 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. In this embodiment, the bonding unit 23 spans the slot 211, and the RFID device 22 is fixed to the bonding unit 23 and located in the slot 211. The RFID chip 221 and the like The conductive strips 222, 223 are disposed adjacent to one of the sides 213 of the slot 211, wherein the side 213 is opposite to the notch 212. It should be noted that the RFID chip 221 and the conductive strips 222, 223 may also be disposed adjacent to either side of the slot 211. The actual measurement results show that the radio frequency identification tag 2 of the present invention having a conductive substrate preferably has a radiation direction toward the notch 212 of the conductive substrate 21.

It should be noted that, in this embodiment, the conductive substrate 21 has a substantially square structure. In other applications, the conductive substrate 21 can have a substantially rectangular structure (for example, one of the radio frequency identifications shown in FIG. 3). The label plate) is not limited to the above-mentioned external structure.

In addition, the first implementation of the radio frequency identification tag 2 having the conductive substrate may further include an outer cover substrate 24, and the outer cover substrate 24 surrounds the conductive substrate 21, and the notch 212 of the conductive substrate 21 is exposed (see FIG. 4). Shown).

In addition, the radio frequency identification tag 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 26 is attached to the surface of the automobile windshield 25, and the heat insulating paper 26 is equivalent to the conductive substrate 21 in FIG. Therefore, a hole 261 having a notch is formed in the heat insulating paper 26, and the RFID device 22 is attached to the heat insulating paper 26, so that the RFID device 22 is disposed in the 261 slot of the heat insulating paper 26. The effect of the radio frequency identification tag 2 having the conductive substrate as shown in FIG. 2 can be exerted.

Moreover, the radio frequency identification tag having the conductive substrate of the present invention can also be applied to the management of books, as shown in FIG. 6. The radio frequency identification tag 2 of the present invention having a conductive substrate is laid flat on the outer or inner page of each book 27 The face is oriented such that the notch 212 of the conductive substrate 21 faces a reading direction. In the present embodiment, the reading direction is parallel to the width direction of the book 27. Since the radiation direction of the RFID tag 2 having the conductive substrate is preferably in the direction of the notch 212, even if the plurality of books 27 are adjacent to each other, the radio frequency identification tag 2 having the conductive substrate can be radiated. The signals are easily read from the books 27 to facilitate the inventory and management of the books 27.

Referring to Figure 7, 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 second embodiment has a radio frequency identification tag 3 having a conductive substrate, and the radio frequency identification tag 2 having the conductive substrate of the first embodiment of FIG. 2 is different in that, in the second embodiment, the RFID device 32 The antenna structure 321 extends from the two sides of a first conductive strip 322 to two sides of a second conductive strip 323, and the conductive strips 322, 323 and the extending direction of the radio frequency identification wafer 324 are oriented toward the conductive A notch 311 of the substrate 31. However, the conductive strips 322, 323 and the RFID chip 324 may extend toward either side of the slot 312 of the conductive substrate 31.

Referring to Figure 8, 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 third embodiment has a radio frequency identification tag 4 of a conductive substrate and the wireless embodiment of the first embodiment of FIG. 2 having a conductive substrate The frequency identification tag 2 is different in that the RFID device 42 in the third embodiment further includes two extended metal pieces 425, which are respectively located on the RFID chip 421 and the conductive strips 422 and 423 of the RFID device 42 and are electrically connected. The antenna structure 424 of the RFID device 42, that is, the antenna structure 424 of the third embodiment is a dipole antenna. The shape of the extended metal strips 425 is substantially U-shaped in the present embodiment, which are respectively located on two sides of the antenna structure 424, and the openings of the extended metal strips 425 are opposite to each other.

Referring to FIG. 9, there is shown a schematic diagram of a radio frequency identification tag having a conductive substrate according to a fourth embodiment of the present invention. The radio frequency identification tag 5 of the fourth embodiment having a conductive substrate comprises a conductive substrate 51, an RFID device 52 and a combining unit 53. The radio frequency identification tag 5 having the conductive substrate of the fourth 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 52 in the fourth embodiment further includes An extension substrate 521, the extension substrate 521 is coupled to the conductive substrate 51, and preferably one side of the extension substrate 521 is flanked by one side of the slot 511 of the conductive substrate 51, wherein one of the RFID devices 52 The first conductive strip 522 is electrically connected to the extension substrate 521. The antenna structure 523 of the RFID device 52 is electrically connected to the second conductive strip 524 and the extension substrate 521 of the RFID device 52 to form a loop structure. In addition, the antenna structure 523 further includes an extension metal piece 525 electrically connected to the circuit structure. That is, the antenna structure 523 of the third embodiment is a monopole antenna.

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. But, no In the design of the line RFID tag, the input impedance of the antenna structure of the designed RFID device is no longer a simple 50Ω, but has the impedance characteristics of both the real part and the imaginary part, and the RFID chip has a charging circuit, which makes it high. The characteristics of the 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.

The RFID device of the present invention is disposed in a slot of a conductive substrate, and the signal is coupled to the conductive substrate by an inductive coupling, and then the signal is radiated and transmitted by the conductive substrate, and utilized. The antenna design technique described above adjusts the size and shape of the slot or adjusts the characteristics of the antenna structure so that the antenna structure can be impedance-conjugated with the RFID chip to achieve maximum radiation power output. According to the actual measurement result, the RFID tag with the conductive substrate of the present invention can effectively read the distance in the air by 4.0 to 5.0 meters.

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, the radio frequency identification tag with the conductive substrate of the present invention has excellent radiation efficiency by adjusting the size and shape of the slot or adjusting the characteristics of the antenna structure. Rate, so you can increase the reading distance. Furthermore, the RFID device is combined with the conductive substrate by using the bonding unit. In addition to increasing the tolerance of the RFID device, the conductive substrate and the bonding unit can also support and protect the RFID device. Therefore, the present invention has The RFID tag of the conductive substrate has excellent durability and 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‧‧‧Substrate

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 circuit board

21‧‧‧Electrical substrate

211‧‧‧ slots

212‧‧‧ gap

22‧‧‧RFID devices

221‧‧‧RFID chip

222, 223‧‧‧ Conductive tape

224‧‧‧Antenna structure

23‧‧‧Combination unit

24‧‧‧Overlay substrate

25‧‧‧Automobile windshield

26‧‧‧Insulation paper

261‧‧‧Slots

27‧‧‧ books

3‧‧‧The second embodiment of the present invention has a radio frequency identification tag of a circuit board

31‧‧‧Electrical substrate

311‧‧‧ gap

312‧‧‧Slots

32‧‧‧RFID devices

321‧‧‧Antenna structure

322‧‧‧First Conductive Tape

323‧‧‧Second conductive tape

324‧‧‧RFID chip

33‧‧‧ combination unit

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

41‧‧‧Electrical substrate

42‧‧‧RFID device

421‧‧‧RFID chip

422, 423‧‧‧ Conductive tape

424‧‧‧Antenna structure

425‧‧‧Extended metal sheet

43‧‧‧ combination unit

5‧‧‧Fourth embodiment of the present invention has a radio frequency identification tag of a conductive substrate

51‧‧‧Electrical substrate

511‧‧‧Slots

52‧‧‧RFID devices

521‧‧‧Metal substrate

522‧‧‧First Conductive Tape

523‧‧‧Antenna structure

524‧‧‧Second conductive tape

525‧‧‧Extended metal sheet

53‧‧‧ combination unit

1 shows a schematic diagram of a radio frequency identification system tag having a conductive substrate according to US Pat. No. 6,914,562; FIG. 2 is a schematic diagram showing a radio frequency identification tag having a conductive substrate according to a first embodiment of the present invention; FIG. 3 shows a first embodiment of the present invention. FIG. 4 is a schematic diagram showing a third aspect of a radio frequency identification tag having a conductive substrate according to a first embodiment of the present invention; FIG. 5 is a diagram showing a radio frequency of a radio frequency identification tag having a conductive substrate according to the present invention; FIG. 6 is a schematic diagram showing application of a radio frequency identification tag having a conductive substrate to a book management operation; FIG. 7 is a diagram showing a radio frequency identification tag having a conductive substrate according to a second embodiment of the present invention; Schematic diagram 8 is a schematic view showing a radio frequency identification tag having a conductive substrate according to a third embodiment of the present invention; and FIG. 9 is a view showing a radio frequency identification tag having a conductive substrate according to a fourth 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‧‧‧ gap

22‧‧‧RFID devices

221‧‧‧RFID chip

222, 223‧‧‧ Conductive tape

224‧‧‧Antenna structure

23‧‧‧Combination unit

Claims (15)

A radio frequency identification (RFID) tag having a conductive substrate, comprising: a conductive substrate having a slot, the slot forming a notch on a side of the conductive substrate, and the slot penetrates the conductive a radio frequency identification device having a radio frequency identification chip, two conductive strips, and an antenna structure, wherein the conductive strips are respectively disposed at two ends of the radio frequency identification chip, the radio frequency identification chip, the conductive strips, and The antenna structure is disposed in the slot; and a combining unit is coupled to the radio frequency identification device and 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 1, wherein the conductive substrate is made of copper. The radio frequency identification tag of claim 1, wherein the antenna structure is a dipole antenna. The radio frequency identification tag of claim 1, wherein the antenna structure is a monopole antenna. The radio frequency identification tag of claim 1, wherein the antenna structure is a small loop antenna. The radio frequency identification tag of claim 1, wherein the antenna structure forms a loop structure with the radio frequency identification chip and the conductive strips. The radio frequency identification tag of claim 1, wherein the radio frequency identification The device further includes two extension metal pieces electrically connected to the antenna structure. The radio frequency identification tag of claim 1, wherein the radio frequency identification device further comprises an extension substrate, a first conductive strip is electrically connected to the extension substrate, and the two ends of the antenna structure are electrically connected to a second conductive strip and the The substrate is extended to form a loop structure. The radio frequency identification tag of claim 9, wherein the antenna structure further comprises an extended metal piece electrically connected to the circuit structure. The radio frequency identification tag of claim 1, wherein the antenna structure extends from two sides of one conductive strip to two sides of the other conductive strip, and the conductive strips and the extending direction of the radio frequency identification chip are oriented toward the gap. The radio frequency identification tag of claim 1, wherein the bonding unit is an adhesive layer. The radio frequency identification tag of claim 1, wherein the combining unit spans the slot, the radio frequency identification device is fixed in the bonding unit and located in the slot. 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 an outer cover substrate surrounding the conductive substrate and exposing the gap.