JP5139941B2 - RFID antenna - Google Patents

Description

  The present invention relates to an RFID antenna formed on a printed circuit board.

  An RFID chip is mounted on a printed circuit board, and an ID is read in each process of product assembly using the printed circuit board, so that the product being assembled is identified and parts corresponding to the product are supplied accurately and efficiently. Production systems are known. This system has an advantage of improving production efficiency in multi-mix production. In addition, the application of RFID chips has been studied and put into practical use in various fields such as product inventory management at the distribution stage and product identification at the maintenance stage even after product shipment.

  When an RFID chip is mounted on a substrate, an RFID antenna may be formed on the printed circuit board for the purpose of improving transmission / reception performance and reducing the overall cost. The technique described in Patent Document 1 is a technique related to an RFID tagging apparatus provided at a low cost. The antenna means is formed on a printed circuit board, and there is no need for a separate circuit board for supporting the antenna, the overall tag size can be reduced, and the tag manufacturing process can be simplified.

Japanese Patent No. 36553099

  However, although the technology of Patent Document 1 does not require a separate circuit board for supporting the antenna and can reduce the cost, a mechanism for optimizing the reception performance of the antenna to suit the usage environment of the RFID chip Is not suggested.

  As for the reception performance, the optimum antenna configuration, that is, the optimum coil length can be determined from the frequency of the RF signal of the RFID chip to be applied. However, in reality, the RFID chip mounted on the substrate, the antenna section formed on the substrate (the coil length calculated as optimal in design), and each electronic component is mounted on the substrate and incorporated as a device. There are many cases in which the expected reception performance cannot be ensured with the optimum coil length at the time of design due to various relations with the determined state.

  Therefore, even if the technique of Patent Document 1 is applied, a reception device is confirmed after creating a prototype, and an antenna portion on a printed circuit board formed in the same manner as a signal line (a coil calculated as optimal in design) The length will need to be adjusted. That is, depending on the reception situation, it may be necessary to recreate a printed circuit board in which the antenna forming unit is corrected. This is a problem in that from the standpoint of high-mix low-volume production and shortening the production lead time, it leads to an increase in the cost of reworking the substrate and a production delay for reworking. This problem cannot be solved even if the technique described in Patent Document 1 is applied.

  The present invention has been made in view of the above points. When an antenna pattern is formed on a printed circuit board, a plurality of antenna patterns having different performances are formed in advance, and they are appropriately selected and used. An object of the present invention is to provide a printed circuit board with an antenna pattern that makes it possible to avoid reworking the printed circuit board as much as possible, and an electronic device using the printed circuit board.

  A first printed circuit board with an RFID antenna of the present invention is a printed circuit board in which an antenna for an RFID chip is formed as a signal line antenna pattern, and the mounting position of the RFID chip on the printed circuit board is changed. The frequency characteristics of the antenna can be changed.

  A second printed circuit board with an RFID antenna according to the present invention is an RFID chip and a printed circuit board on which the RFID chip is mounted. The printed circuit board includes a plurality of antennas for the RFID chip in a coil shape as a plurality of antenna patterns. A plurality of mounting locations where the RFID chip can be mounted, and the RFID chip is mounted by appropriately selecting one of the mounting locations. One or more of the antenna patterns can be selected, and the frequency characteristics of the antenna can be changed.

  According to a third printed circuit board with an RFID antenna of the present invention, in the second printed circuit board of the present invention, a plurality of mounting locations where the RFID chip can be mounted can be further mounted with a circuit shorting component, The frequency characteristics of the antenna can be changed by appropriately selecting and arranging the mounting positions of the RFID chip and the circuit short-circuit component.

  According to a fourth printed circuit board with an RFID antenna of the present invention, in the second or third printed circuit board of the present invention, the plurality of antenna patterns formed in the coil shape are antennas formed in a coil shape at substantially the same center. In the pattern, the change in the frequency characteristic of the antenna is a change in the frequency characteristic due to the fact that the length of the antenna pattern can be adjusted by selecting to increase or decrease the number of coil turns.

  The electronic device of the present invention is characterized by mounting the first to fourth printed circuit boards of the present invention.

  According to the present invention, a plurality of antenna patterns having different performances are formed in advance on a printed circuit board, and these are appropriately selected and used, so that the printed circuit board with the antenna pattern can avoid the reworking of the printed circuit board as much as possible. And an electronic device using the substrate can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a plurality of mounting locations where a plurality of antenna patterns and RFID chips can be mounted on a part of the printed circuit board of the present invention. If this printed circuit board 1 is the main board of the apparatus, many other components are mounted (not shown). For example, if this printed circuit board is a personal computer motherboard, the printed circuit board is mounted on the personal computer housing and the personal computer main body is assembled. Any electronic device in which the printed board is incorporated can be applied to all electronic devices. An antenna pattern 11 is formed in a coil shape on the surface of the printed circuit board 1. On the back surface of the printed circuit board, signal lines 12 to the RFID chip mounting locations 13, 14 and 15 are formed as part of the antenna pattern. In FIG. 1, the part shown with the broken line is the signal line 12 which is a part of an antenna pattern.

  Here, portions 13, 14 and 15 for mounting RFID chips and an antenna pattern 11 formed in a coil shape are provided on the front surface side of the printed circuit board 1, and a signal which is a part of the antenna pattern is provided on the back surface side of the printed circuit board. Line 12 is provided. However, if the printed circuit board has a plurality of layers, the antenna pattern may be divided into each layer. Further, whether the RFID chip is mounted on the front surface or the back surface may be selected as appropriate at the design stage.

  FIG. 2 shows a short-circuit chip 3 having the same shape as the RFID chip 2. By electrically connecting the RFID chip 2 and the antenna pattern 11 formed on the printed circuit board, the RFID chip 2 can transmit and receive signal radio waves to the chip via the antenna pattern 12. Although the short-circuit chip 3 is shown as a chip having the same shape as the RFID chip 2, the shape may be different as long as the short-circuit chip 3 can be alternatively mounted at the place where the RFID chip is mounted.

  FIG. 3 is a diagram showing a mounting example corresponding to mounting 2 in FIG. 4 to be described later. In order to facilitate understanding of the antenna pattern 11 described with reference to FIG. 1, the inner periphery of the coiled antenna pattern is distinguished from the solid line 11a, the intermediate portion is distinguished from the double line 11b, and the outer periphery is distinguished from the thick line 11c.

  That is, the printed circuit board 1 can select the number of coil turns of the antenna pattern by appropriately and selectively mounting the RFID chip 2 and the short-circuit chip 3 on the RFID chip mounting locations 13, 14, and 15.

  FIG. 4 is a diagram specifically showing the relationship between the arrangement pattern of the RFID chip 2 and the short-circuit chip 3 at the RFID chip mounting locations 13, 14 and 15, and the corresponding number of coil turns.

  First, the mounting 2 shown in the middle of FIG. 4 will be described in comparison with FIG. 3 shows a state where neither the RDID chip 2 nor the short-circuit chip 3 is mounted, and the circuit at this position is open. The RFID chip 2 is mounted on the mounting portion 14, and the short-circuit chip 15 is mounted on the mounting portion 15. In this case, the inner peripheral portion 11a and the intermediate portion 11b of the antenna pattern 11 are electrically connected to the RFID chip 2 mounted on the mounting portion 12 by the signal line 12 formed on the back surface of the RFID chip 2, and serve as an antenna. The inner peripheral part 11a and the intermediate part 11b function. The coil corresponding to the inner peripheral part 11a is L1 (n turns), the coil corresponding to the intermediate part 11b is L2 (2 turns), and an n + 2 turn coil is selected as the antenna. Since the outer peripheral part 11 c is short-circuited by the short-circuit chip 3 as shown in the mounting 2, it does not function as the antenna part of the RFID chip 2.

  In general, the wavelength or frequency of radio waves received by an RFID chip is basically determined. For example, in the case of the HF band, it is 13.56 MHz. Therefore, it is possible to determine the antenna pattern on the printed circuit board based on that. In other words, if the number of antenna turns is increased and the pattern is lengthened, the resonance frequency is lowered and optimized for receiving radio waves with a low reception frequency. Conversely, if the number of turns is reduced and the pattern is shortened, the resonance frequency is raised, Optimized to receive radio waves with high reception frequency.

  However, in actuality, the antenna pattern based on the simulation result by the optimization calculation does not become an optimal antenna that matches the reception frequency. This is because a large number of components that affect radio waves such as ICs, resistors, and capacitors are mounted around the antenna of the RFID chip formed on the printed circuit board. Further, there are various factors other than the above-mentioned mounted parts, such as the metal parts constituting the casing of the present application and the copper foil and material of the printed board being slightly different for each manufacturer.

  As mentioned above, including the factors that affect various radio waves, it is difficult to perform simulation before prototyping. Occur. In order to avoid reworking the printed circuit board as much as possible, the gist of the present invention is to produce a printed circuit board in which the mounting 1 and the mounting 3 that can be selected for the mounting 2 shown in FIG.

  For example, if the antenna pattern based on the simulation result is the component arrangement shown in FIG. 3, that is, if the number of coil turns of the antenna pattern of the mounting 2 in FIG. 4 is n + 2, the mounting 1 with the reduced number of turns (the number of turns n) Then, mounting 3 (the number of turns n + 4) with an increased number of turns may be formed. When it is necessary to change the reception characteristics of the antenna due to influence factors after mounting, an antenna pattern in which the number of turns is increased with respect to the number of turns n of the optimized calculation value by appropriately arranging the RFID chip 2 and the short-circuit chip 3. It is also possible to adopt an antenna pattern with a reduced number of turns.

  Next, the upper mounting 1 and the lower mounting 3 shown in FIG. 4 will be described in detail. The upper mounting 1 shows a case where L1 (n turns) of the coiled antenna pattern corresponding to the inner peripheral portion 11a functions as the antenna of the RFID chip 2. The RFID chip 2 is mounted at the mounting location 13, and two short-circuit chips 3 are mounted at the mounting locations 14 and 15.

  The lower mounting 3 has n + 4 windings as an antenna of the RFID chip 2 with the inner peripheral portion L1 (n windings), the intermediate portion L2 (two windings) and the outer peripheral portion L3 (two windings) connected to the RFID chip 2 in series. Indicates when it works. In the mounting locations 13 and 14, the chip is not mounted and the circuit is open. An RFID chip is mounted on the mounting portion 15.

  In the present embodiment, the coiled antenna patterns are arranged in the same center, and signal lines for connection to the RFID chip 2 or the short-circuit chip 3 are arranged at two places in the center portion and the middle portion and one place on the outermost circumference portion. As shown, the number of turns can be adjusted. In addition, signal lines from two locations, the central portion and the intermediate portion, are formed on the back surface of the printed circuit board.

  However, this example is a printed circuit board formation example for reducing the price of the printed circuit board and suppressing the area of the antenna pattern forming portion. If the design allows, the RFID chip is selectively disposed. Thus, it is only necessary to form at least two patterns on the substrate that can change the length of the antenna pattern.

  As described above, by forming a plurality of antenna patterns with different reception performance in advance on a printed circuit board and selecting and using them appropriately, when mass-producing the circuit board and electronic devices using the circuit board, It is possible to avoid reworking the printed circuit board as much as possible.

It is a figure which shows a part of printed circuit board which provided the mounting location of the antenna pattern and chip component of embodiment of this invention. It is a figure which shows the RFID chip and short circuit chip which are mounted in the printed circuit board of this invention. It is a figure which shows the example by which the chip component was mounted in the printed circuit board of this invention. It is the figure which showed the relationship between the mounting pattern of the chip components in the mounting location, and the number of coil turns selected.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 RFID chip 3 Short circuit chip 11 Antenna pattern 12 Signal line which connects an antenna pattern and a chip 13 Mounting location of RFID chip or short circuit chip 14 Mounting location of RFID chip or short circuit chip 15 Mounting location of RFID chip or short circuit chip

Claims (2)

An RFID chip and a printed circuit board on which the RFID chip is mounted, wherein the antenna for the RFID chip is formed in a coil shape at substantially the same center as a plurality of antenna patterns on the printed circuit board, and the RFID A plurality of mounting locations where a chip can be mounted are provided without straddling the antenna pattern, and the plurality of antenna patterns are mounted by appropriately selecting one of the mounting locations and mounting the RFID chip. One or more of these can be selected, and a plurality of mounting locations where the RFID chip can be mounted can be further mounted with a component for short-circuiting the circuit. All the mounting locations corresponding to the side coil are not mounted, and the mounting location of the outer peripheral side coil is more than the mounting location of the RFID chip. The mounting portion is by implementing all components for the circuit shorts, RFID, characterized in that to be able to change the frequency characteristics by adjusting the length of the antenna pattern by decreasing the choice of coil turns of the antenna Printed circuit board with antenna. The electronic device which mounted the printed circuit board of Claim 1 .

Images