RFID tags, plastic bottles, and antennas

Abstract

An RFID tag includes an IC chip for recording identification information, a ring-shaped conductor connected to the IC chip, and an antenna portion having two conductor portions connected to the ring-shaped conductor and extending from the ring-shaped conductor in directions away from each other. The RFID tag is provided on a surface of a container for containing a liquid.

Description

TECHNICAL FIELD

[0001] The present application relates to an RFID (Radio Frequency Identification) module, a plastic bottle, and an antenna. BACKGROUND

[0002] For logistics management, commodity management, an RFID tag that is attached to an adherend is becoming widespread. The RFID tag is a tag having an RFID tag sheet. The RFID tag sheet includes an IC chip and an antenna electrically connected to the IC chip. The RFID tag sheet is also sometimes referred to as a wireless tag, an IC tag, an RF-ID tag, or an RF tag. In a case where the adherend to which such an RFID tag is attached is a container for containing a liquid such as a plastic bottle for beverages, sometimes an obstacle is caused to reading of identification information. The reason is considered to be that, in a case where the antenna exists in the vicinity of the liquid, the characteristics of the antenna are changed under the influence of the liquid, the electric wave is absorbed by the liquid, or the like.

[0003] In Patent Literature 1, an RFID tag that can read identification information well even in a case where a liquid that can have an influence on reading of the identification information is contained in an adherend is disclosed. The RFID tag disclosed in Patent Literature 1 has a configuration in which the antenna protrudes from the adherend. Thereby, the distance from the antenna to the liquid becomes long, the above influence is reduced, and thus the identification information stored in the RFID tag can be read well.

[0004] (Prior Art Documents)

[0005] (Patent Literature)

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2006-277524 SUMMARY

[0007] (Problems to be Solved by the Invention)

[0008] However, in the related art disclosed in Patent Literature 1, since the configuration is such that the antenna protrudes from the adherend, there is a concern that an obstacle such as breakage of the antenna is caused at the time of storage, the time of carrying, or the like of the container, and there is room for improvement.

[0009] The present application has been achieved in view of the above, and an object thereof is to obtain an RFID tag that can read identification information without causing an obstacle such as breakage of an antenna caused by handling of a container.

[0010] (Means for Solving the Problems)

[0011] To solve the above object, an RFID tag according to the present application is provided on a surface of a container for containing a liquid, and includes:

[0012] An IC chip for recording identification information;

[0013] A ring-shaped conductor connected to the IC chip;

[0014] An antenna portion having two straight elements as straight-shaped conductors, the two straight elements being connected to the ring-shaped conductor and extending from the ring-shaped conductor in directions away from each other, and the two straight elements being set to an electrical length of approximately a multiple of 1 / 4 of a wavelength of a frequency of use.

[0015] (EFFECTS OF THE INVENTION)

[0016] According to the present application, an effect is achieved that the reading of identification information is performed without causing a malfunction of an antenna due to handling of a container. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a perspective view of a liquid container 300 provided with an RFID tag according to an embodiment of the present application.

[0018] Figure 2 is a diagram showing a configuration example of an RFID tag.

[0019] Figure 3A is a diagram showing an impedance characteristic of an RFID tag measured in a state where no liquid is contained in a container.

[0020] Figure 3B is a diagram showing an impedance characteristic of an RFID tag measured in a state where a liquid is contained in a container.

[0021] Figure 4 is a diagram showing a configuration example of a comparative example of an RFID tag according to an embodiment of the present application.

[0022] Figure 5A is a diagram showing an impedance characteristic of the comparative example measured in a state where no liquid is contained in a container.

[0023] Figure 5B is a diagram showing an impedance characteristic of the comparative example measured in a state where a liquid is contained in a container.

[0024] Figure 6 is a diagram showing a configuration example of an RFID tag according to a first modified example.

[0025] Figure 7A is a diagram showing an impedance characteristic of an RFID tag measured in a state where no liquid is contained in a container.

[0026] Figure 7B is a diagram showing an impedance characteristic of an RFID tag measured in a state where a liquid is contained in a container.

[0027] Figure 8 FIG. 7 is a diagram showing a configuration example of an RFID tag of a second modification example.

[0028] Figure 9A FIG. 8 is a diagram showing an impedance characteristic of the RFID tag measured in a state where no liquid is contained in the container.

[0029] Figure 9B FIG. 9 is a diagram showing an impedance characteristic of the RFID tag measured in a state where the liquid is contained in the container.

[0030] Figure 10 FIG. 10 is a diagram showing a configuration example of an RFID tag of a third modification example.

[0031] Figure 11A FIG. 11 is a diagram showing an impedance characteristic of the RFID tag measured in a state where no liquid is contained in the container.

[0032] Figure 11B FIG. 12 is a diagram showing an impedance characteristic of the RFID tag measured in a state where the liquid is contained in the container.

[0033] Figure 12 FIG. 13 is a diagram showing a configuration example of an RFID tag of a fourth modification example.

[0034] Figure 13A FIG. 14 is a diagram showing an impedance characteristic of the RFID tag measured in a state where no liquid is contained in the container.

[0035] Figure 13B FIG. 15 is a diagram showing an impedance characteristic of the RFID tag measured in a state where the liquid is contained in the container.

[0036] Figure 13A FIG. 16 is a diagram showing a configuration example of an RFID tag of a fifth modification example.

[0037] Figure 13B FIG. 17 is a diagram showing a configuration example of an RFID tag of a sixth modification example.

[0038] Figure 13A FIG. 18 is a diagram showing a configuration example of an RFID tag of a seventh modification example.

[0039] Figure 13B FIG. 19 is a diagram showing a configuration example of an RFID tag of an eighth modification example.

[0040] Figure 13A FIG. 20 is a first diagram showing a frequency characteristic of an RFID tag disposed in air.

[0041] Figure 13B FIG. 21 is a second diagram showing a frequency characteristic of an RFID tag disposed in air.

[0042] Figure 14 is a third graph showing the frequency characteristics of the RFID tag disposed in air.

[0043] Figure 13A is a fourth graph showing the frequency characteristics of the RFID tag disposed in air.

[0044] Figure 13B is a fifth graph showing the frequency characteristics of the RFID tag disposed in air.

[0045] Figure 15 is a first graph for explaining the frequency characteristics of the RFID tag capable of being disposed in either one of air and water.

[0046] Figure 16 is a second graph for explaining the frequency characteristics of the RFID tag capable of being disposed in either one of air and water.

[0047] Figure 17 is a third graph for explaining the frequency characteristics of the RFID tag capable of being disposed in either one of air and water.

[0048] Figure 18A is a fourth graph for explaining the frequency characteristics of the RFID tag capable of being disposed in either one of air and water.

[0049] Figure 18B is a graph showing the frequency characteristics of the RFID tag shown in Figure 18C

[0050] Figure 18D is a graph showing the frequency characteristics of the RFID tag shown in Figure 18E

[0051] Figure 18A to Figure 18E is a graph showing the frequency characteristics of the RFID tag shown in Figure 18A

[0052] Figure 18A is a graph showing the frequency characteristics of the RFID tag shown in Figure 18B

[0053] Figure 18B is a graph showing a configuration example of the RFID tag of the ninth modification example. DETAILED DESCRIPTION

[0054] ​​​​Embodiments of the present application will be described in detail with reference to the accompanying drawings. In the following description, like parts are designated with like reference numbers, and description thereof will not be repeated. In addition, the scale of each component in each drawing is sometimes different from the actual scale in order to facilitate understanding. Note that in each mode, directions such as parallel, right angle, horizontal, vertical, up and down, left and right, and the like are allowed to deviate to an extent that does not impair the effect of the present application. In addition, the X-axis direction, the Y-axis direction, and the Z-axis direction each represent a direction parallel to the X-axis, a direction parallel to the Y-axis, and a direction parallel to the Z-axis, respectively. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. The XY plane, the YZ plane, and the ZX plane each represent an imaginary plane parallel to the X-axis and the Y-axis, an imaginary plane parallel to the Y-axis and the Z-axis, and an imaginary plane parallel to the Z-axis and the X-axis, respectively. In the following description, the X-axis direction, the Y-axis direction, and the Z-axis direction are sometimes referred to as the up-down direction, the left-right direction, and the front-back direction, respectively. In addition, the XY plane, the YZ plane, and the ZX plane are sometimes referred to as the up-down plane, the left-right plane, and the front-back plane, respectively. Figure 18C After that, the direction indicated by the arrow in the X-axis direction is set as the positive X-axis direction, and the direction opposite to the direction is set as the negative X-axis direction. The direction indicated by the arrow in the Y-axis direction is set as the positive Y-axis direction, and the direction opposite to the direction is set as the negative Y-axis direction. The direction indicated by the arrow in the Z-axis direction is set as the positive Z-axis direction, and the direction opposite to the direction is set as the negative Z-axis direction. The X-axis direction is equal to the height direction when the container described later is viewed from the side. The Y-axis direction is equal to the lateral width direction when the container described later is viewed from the side. The Z-axis direction is equal to the longitudinal depth direction when the container described later is viewed from the side.

[0055] Figure 18C is a perspective view of a container 300 for containing a liquid 200 provided with an RFID tag 100, which is an embodiment of the present application. Figure 18D The container 300 illustrated is a container body (a plastic bottle) made of polyethylene terephthalate for containing a liquid 200. The liquid 200 is a liquid similar to water such as a refreshing drink, mineral water, or the like. Note that the liquid 200 is not limited to this, and can be oil, alcohol, or the like. In addition, the liquid 200 can be any mixture of water, oil, and alcohol (for example, a liquid in which water is mixed in ethanol, or the like). A cap portion 301 is provided at the top end portion of the container 300 in the positive X-axis direction. A transparent band-shaped label 302 is wrapped around the outer peripheral surface of the container 300. The RFID tag 100 is provided on the label 302. The RFID tag 100 exists in the air (in the atmosphere). That is, the atmosphere around the container 300 provided with the RFID tag 100 is air.

[0056] Note that the container 300 is a container body capable of containing the liquid 200, and can be a glass container body or a Tupperware (registered trademark) or the like. Hereinafter, for the sake of simplicity, the liquid 200 will be simply referred to as "liquid" and the container 300 will be simply referred to as "container". In addition, since the dipole antenna is provided in the RFID tag 100, the RFID tag 100 is attached to the container 300 in a longitudinal manner, but the method of attaching the RFID tag 100 to the container 300 is not limited thereto.

[0057] Next, the Figure 18D An example of the configuration of the RFID tag 100 will be described. Figure 18E is a view showing an example of the configuration of the RFID tag 100. The RFID tag 100 includes a band-shaped sheet body 40, an IC chip 10 for recording identification information, a ring-shaped conductor 20, and an antenna portion 30.

[0058] The sheet body 40 is a band-shaped film formed by laminating a plurality of synthetic resin films such as polyethylene terephthalate, polypropylene, or the like. The IC chip 10, the ring-shaped conductor 20, and the antenna portion 30 are arranged, for example, in a manner of being sandwiched between the laminated plurality of synthetic resin films. Note that the IC chip 10, the ring-shaped conductor 20, and the antenna portion 30 can be directly provided to the container body or can be provided to the label 302 of the container.

[0059] The IC chip 10 has an internal capacitor, and a matching circuit is configured by the inductance of the antenna portion 30 and the internal capacitor of the IC chip 10.

[0060] The ring-shaped conductor 20 is a conductive wiring pattern in the shape of a loop of one turn or less when the sheet body 40 is viewed in the Z-axis direction.

[0061] The ring-shaped conductor 20 is electrically connected to the IC chip 10 and the antenna portion 30. When the identification information recorded in the IC chip 10 is read by a reader, if the antenna portion 30 receives an electric wave in the UHF band, for example, an electric wave near 920 MHz, a current flows in the ring-shaped conductor 20 under the resonance action. Thus, a power for operating the IC chip 10 is generated. If the IC chip 10 is operated, the identification information recorded in the IC chip 10 is encoded by the IC chip 10, and the encoded data is wirelessly transmitted to a communication device such as a reader using an electric wave near 920 MHz as a carrier wave. The reader that has received the signal decodes the signal and transmits it to an external machine. As such, the RFID tag 100 of the present embodiment is a passive type wireless tag of the electric wave type that does not have a power source (battery) for storing and transmitting identification information. Therefore, compared to an active type wireless tag having a battery, since the battery is not provided, miniaturization and low cost can be achieved.

[0062] The antenna portion 30 is a dipole antenna configured to exhibit resonance characteristics with respect to the frequency of a radio wave for wireless communication, such as a frequency in the UHF band. The antenna portion 30 has an electrical length corresponding to approximately λ / 2 (λ is the communication wavelength) as a whole.

[0063] The antenna portion 30 has a configuration that achieves impedance conjugate matching with the IC chip 10 with respect to a radio wave of a frequency of, for example, approximately 920 MHz (for example, 860 MHz to 960 MHz, and more preferably 915 MHz to 935 MHz), even in a state in which the container 300 is filled with a liquid and there is a liquid in the vicinity of the antenna. The antenna portion 30 includes two conductor portions (a conductor portion 30A and a conductor portion 30B) as a configuration for achieving impedance conjugate matching with the IC chip 10. The conductor portion 30A and the conductor portion 30B are conductive wiring patterns connected to the annular conductor 20 and extending in directions away from each other from the annular conductor 20. The conductive wiring patterns can be formed by a known method such as punching processing, etching processing of a copper foil or an aluminum foil, a method of forming based on plating, screen printing of a metal paste, a metal wire, or the like, and in this embodiment, are formed by etching of an aluminum foil.

[0064] The conductor portion 30A and the conductor portion 30B are formed to be linearly symmetrical with respect to an imaginary line VL passing through the approximate center of the IC chip 10. The imaginary line VL is a line parallel to the XY plane and extending in the Y-axis direction. The imaginary line VL is also a line that approximately bisects the RFID tag 100 in the X-axis direction.

[0065] Each of the conductor portion 30A and the conductor portion 30B has an electrical length corresponding to approximately λ / 4 (λ is the communication wavelength). The condition for impedance matching of the antenna portion 30 is a case in which the impedance when viewed from the signal source side of the load and the impedance when viewed from the load side of the signal source become complex conjugates of each other. Therefore, if the signal source impedance Zs from the load side is Zs = Rs + jXs, the load impedance Zl is Zl = Rs - jXs, and the maximum power is transmitted.

[0066] Note that, since the conductor portion 30A and the conductor portion 30B are linearly symmetrical with respect to the imaginary line VL, the configuration of the conductor portion 30A will be described below. The configuration of the conductor portion 30B will be described by replacing the extension direction of the conductor portion 30A in the X-axis direction with the opposite direction, and the description thereof will be omitted.

[0067] The conductor portion 30A includes a first element 1, a second element 2, a third element 3, and a fourth element 4.

[0068] The first element 1 is a conductive wiring pattern of a meandering (winding) shape extending in the negative X-axis direction from the annular conductor 20. The first element 1 is a meandering element.

[0069] The end portion of the first element 1 in the positive X-axis direction is connected to the loop conductor 20. The connection site of the first element 1 to the loop conductor 20 is, for example, the peripheral edge portion on the positive Y-axis direction side of the loop conductor 20. The first element 1 extends from the connection site to the loop conductor 20 by a predetermined angle (for example, 30° to 60°) in the negative X-axis direction by a certain distance, and then further extends in the negative X-axis direction from the portion extended by the certain distance. Note that the shape of the first element 1 is not limited to the illustrated example, and can be, for example, a shape in which the first element 1 extends from the connection site to the loop conductor 20 by a certain distance in the positive Y-axis direction, and then is bent perpendicularly from the portion extended by the certain distance to extend in the negative X-axis direction.

[0070] The first element 1 is connected to the peripheral edge portion on the positive Y-axis direction side of the loop conductor 20, and the width of the entire antenna portion 30 in the X-axis direction is narrowed, so that an RFID label 100 having a smaller ratio of the length to the width can be implemented. Therefore, even in a case where the RFID label 100 is attached to, for example, a small-capacity plastic bottle or the like having a relatively small height in the X-axis direction and a small label, the RFID label 100 can be arranged in a region that does not interfere with the display of the product or the like of the plastic bottle.

[0071] Note that the connection site of the first element 1 to the loop conductor 20 is not limited to this, and can be the peripheral edge portion on the negative X-axis direction side of the loop conductor 20. With this configuration, the first element 1 can be arranged in the region on the negative X-axis direction side of the loop conductor 20. Therefore, the width of the entire antenna portion 30 in the Y-axis direction is narrowed, so that an RFID label 100 having an elongated shape can be implemented. Therefore, even in a case where the RFID label 100 is attached to, for example, a large-capacity plastic bottle or the like having a relatively large height in the X-axis direction, the RFID label 100 can be arranged in a region that does not interfere with the display of the product or the like of the plastic bottle.

[0072] The second element 2 is, for example, a linear conductive wiring pattern extending in the negative X-axis direction from the loop conductor 20. The second element 2 is a linear element.

[0073] The end portion of the second element 2 in the positive X-axis direction is connected to the first element 1 or the loop conductor 20.

[0074] In a case where the second element 2 is connected to the first element 1, the second element 2 is connected, for example, in the vicinity of the connection site of the first element 1 to the loop conductor 20. The second element 2 extends from the connection site in the negative X-axis direction by a certain distance.

[0075] In a case where the second element 2 is connected to the loop conductor 20, the second element 2 is connected, for example, to the peripheral edge portion on the positive Y-axis direction side of the loop conductor 20.

[0076] The second element 2 can be provided on the negative Y-axis direction side of the first element 1, or on the positive Y-axis direction side of the first element 1.

[0077] As shown in FIG. 1, the second element 2 is provided on the negative Y-axis direction side of the first element 1. In this case, the area on the negative X-axis direction side of the loop conductor 20 can be effectively utilized. Therefore, the RFID tag 100 having a smaller ratio of the longitudinal width to the lateral width can be realized. Figure 18E As shown in FIG. 1, the second element 2 is provided on the negative Y-axis direction side of the first element 1. In this case, the area on the negative X-axis direction side of the loop conductor 20 can be effectively utilized. Therefore, the RFID tag 100 having a smaller ratio of the longitudinal width to the lateral width can be realized.

[0078] Note that if the gap (separation distance in the Y-axis direction) between the second element 2 and the first element 1 is set to a value of, for example, 0.5 mm to 2.0 mm, it is preferable in terms of easily obtaining the complex conjugate of the impedance of the antenna and the IC chip. If the distance becomes too large, the real part of the impedance becomes large, and it becomes difficult to obtain the complex conjugate with the IC chip. The second element 2 is the main part, and the first element 1 is the sub part.

[0079] The third element 3 is a hook-shaped conductive wiring pattern that extends from the top end of the negative X-axis direction of the second element 2 in a direction different from the direction in which the second element 2 extends. The third element 3 is a hook element. The third element 3 can be a U-shaped pattern, or can be an L-shaped pattern.

[0080] Note that the second element 2 and the third element 3 can be integrally formed in a hook shape.

[0081] As shown in FIG. 1, the second element 2 is provided on the negative Y-axis direction side of the first element 1. In this case, the area on the negative X-axis direction side of the loop conductor 20 can be effectively utilized. Therefore, the RFID tag 100 having a smaller ratio of the longitudinal width to the lateral width can be realized. Figure 19A to Figure 20D As shown in FIG. 1, the second element 2 is provided on the negative Y-axis direction side of the first element 1. In this case, the area on the negative X-axis direction side of the loop conductor 20 can be effectively utilized. Therefore, the RFID tag 100 having a smaller ratio of the longitudinal width to the lateral width can be realized.

[0082] A gap is formed between the portion of the third element 3 that extends toward the loop conductor 20 and the second element. This gap (separation distance in the Y-axis direction) is set to a value of, for example, 1.0 mm to 30.0 mm. In this gap, a plurality of fourth elements 4 are provided.

[0083] The fourth element 4 is a conductive wiring pattern that extends from the second element 2 toward the third element 3, and forms a lattice-shaped pattern together with the second element 2 and the third element 3. The fourth element 4 is a lattice element.

[0084] In the present embodiment, three fourth elements 4 are used as one example, but the number of fourth elements 4 can be one or more. If the interval in the X-axis direction of adjacent fourth elements 4 is set to a value of, for example, 1.0 mm to 30.0 mm, it is preferable in terms of widening the communicable frequency band and extending the communication distance.

[0085] The electrical lengths of the respective elements are set as follows.

[0086] For example, the length of the first element 1 is set to an electrical length that is a multiple of λ / 4 of the wavelength of the frequency of use. In this case, at least one of the length of the second element 2 and the length of the third element 3 is set to an electrical length that is different from the electrical length that is a multiple of λ / 4. The different electrical length is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0087] Note that, instead of the first element 1, the electrical length of the second element 2 can be set to a multiple of λ / 4 of the wavelength of the frequency of use. In this case, at least one of the electrical length of the first element 1 and the electrical length of the third element 3 is set to an electrical length that is different from the electrical length that is a multiple of λ / 4 of the wavelength of the frequency of use. The different electrical length in this case is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0088] In addition, instead of the first element 1, the total value of the electrical length of the second element 2 and the electrical length of the third element 3 of the L-shaped (inverted L-shaped) can be set to a multiple of λ / 4 of the wavelength of the frequency of use. In this case, the electrical length of the first element 1 is set to an electrical length that is different from the electrical length that is a multiple of λ / 4 of the wavelength of the frequency of use. The different electrical length in this case is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0089] In addition, instead of the first element 1, the total electrical length of the electrical length of the second element 2, the electrical length of the third element 3, and the electrical length of the fourth element 4 (for example, any one of the three fourth elements 4) can be set to a multiple of λ / 4 of the wavelength of the frequency of use. In this case, the electrical length of the first element 1 is set to an electrical length that is different from the electrical length that is a multiple of λ / 4 of the wavelength of the frequency of use. The different electrical length in this case is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0090] Next, the impedance characteristics of the RFID tag 100 will be described using Figure 19A , Figure 19B .

[0091] Figure 19C is a graph showing the impedance characteristics of the RFID tag 100 measured in a state in which the container 300 does not contain the liquid 200. Figure 19D is a graph showing the impedance characteristics of the RFID tag 100 measured in a state in which the container 300 contains the liquid 200.

[0092] The impedance Zc of the RFID tag 100 is set to "Zc = Rc + jXc", and the vertical axis indicates the values of the real and imaginary parts. The addition of the letter "c" is a short for the chip (IC chip 10). The horizontal axis indicates the frequencies of the electric waves for wireless communication. The solid line is a plot of the real parts corresponding to the respective frequencies. The dotted line is a plot of the imaginary parts corresponding to the respective frequencies.

[0093] In Figure 19A to Figure 19D , the value of the real part at 920 MHz is about 8 Ω, and the value of the imaginary part at 920 MHz is about 176 Ω. In Figure 19A , the value of the real part at 920 MHz is about 21 Ω, and the value of the imaginary part at 920 MHz is about 198 Ω. Thus, it is known that the impedance characteristics change depending on the presence or absence of the liquid in the container.

[0094] Figure 19B to Figure 19C , Figure 19B The impedance characteristics shown in FIG. 9A are less disordered than the impedance characteristics of the comparative example described later. Less disorder of the impedance characteristics means less degradation of the antenna performance. The use of the element 31 having the meander shape is effective in reducing the disorder of the impedance characteristics. Figure 19C A comparative example of the present embodiment will be described.

[0095] Figure 19D FIG. 10 is a constitutional example of a comparative example 100A of the RFID tag 100 of the embodiment of the present application. The comparative example 100A includes a meander-shaped wiring pattern, that is, an element 31, instead of the first element 1, the second element 2, and the third element 3.

[0096] The element 31 is a rectangular conductive wiring pattern connected to the loop-shaped conductor 20 and extending from the loop-shaped conductor 20 in the X-axis direction. The element 31 is set to an electrical length of substantially 1 / 4 of the wavelength of the frequency of use. Substantially 1 / 4 includes, for example, about 1 / 3 to 1 / 5 of the wavelength of the frequency of use.

[0097] The element 31 is set to an electrical length of substantially 1 / 4 of the wavelength of the frequency of use. Substantially 1 / 4 includes, for example, about 1 / 3 to 1 / 5 of the wavelength of the frequency of use. Figure 19B , Figure 19C The impedance characteristics of the thus-constituted comparative example 100A will be described.

[0098] Figure 19D FIG. 11 is a graph showing the impedance characteristics of the comparative example 100A measured in a state where the container 300 does not contain the liquid 200. Figure 19C FIG. 12 is a graph showing the impedance characteristics of the comparative example 100A measured in a state where the container 300 contains the liquid 200. As with Figure 20A to Figure 20D and Figure 20A , the vertical axis indicates the values of the real and imaginary parts. The horizontal axis indicates the frequencies of the electric waves for wireless communication. The solid line is a plot of the real parts corresponding to the respective frequencies. The dotted line is a plot of the imaginary parts corresponding to the respective frequencies.

[0099] In Figure 19AIn this case, the real number at 920 MHz has a value of about 17 Ω, and the imaginary number at 920 MHz has a value of about 243 Ω. In Figure 20B In this case, the real number at 920 MHz has a value of about 80 Ω, and the imaginary number at 920 MHz has a value of about 25 Ω.

[0100] In comparison with the impedance characteristics shown in Figure 19B and Figure 20C it is seen that the impedance characteristics shown in Figure 19C and Figure 20D are greatly disturbed. It is considered that the electrical coupling between the meandering shape of the element 31 and the liquid having a dielectric constant ε of "80" is the cause of the great disturbance of the impedance characteristics. For example, in the case where the element 31 is disposed in front of the liquid as viewed from the reader, that is, in the case where the reader, the element 31, and the liquid are arranged in this order, the impedance of the comparative example 100A greatly changes due to the dielectric constant of the liquid. That is, in the comparative example 100A, it is presumed that since the meandering shape of the antenna element is adopted in order to secure the electrical length necessary for the wireless communication of the antenna portion 30, the electrical coupling between the liquid on the back side of the element 31 and the antenna element is strengthened as viewed from the reader, and the impedance characteristics are greatly disturbed. In order to solve such a problem, in the past, measures such as increasing the distance from the antenna element to the liquid by providing a partition between the antenna element and the container to reduce the electrical coupling, and inserting a metal sheet between the antenna element and the container to reduce the electrical coupling have been taken.

[0101] On the other hand, it is known that the electric wave of the UHF band having a relatively high frequency is easily absorbed by a liquid. For example, in the case where there is a liquid between the reader and the element 31, a part of the electric wave transmitted from the reader is absorbed by the liquid in the container, and the remaining weak electric wave is received by the element 31. That is, the reception strength of the electric wave at the element 31 is reduced. Since the element 31 transmits the signal related to the identification information toward the reader using this electric wave as a carrier wave, the weak electric wave transmitted from the comparative example 100A is absorbed by the liquid in the container, and the reception strength of the electric wave at the reader is reduced.

[0102] Further, in the case where there is a liquid between the reader and the element 31, it is known that the wavelength of the electric wave is slightly shortened by the wavelength shortening effect of the liquid when the electric wave passes through the liquid. If the wavelength of the electric wave is shortened, the resonance condition of the antenna portion 30 and the IC chip 10 deviates, the condition of the conjugate matching is not satisfied, and the maximum power cannot be obtained.

[0103] In the comparative example 100A, the meandering shape of the element 31 is adopted, and the electrical length of the element 31 is set to a multiple of the wavelength λ / 4 of the frequency used. Therefore, the present inventors have found that the wireless communication with the reader can become difficult due to the above-mentioned electrical coupling, the wavelength shortening effect, the absorption attenuation of the electric wave, and the like.

[0104] On the contrary, in the RFID tag 100 of the present embodiment, by using at least the antenna element having a shape other than the meander shape, the electrical coupling with the liquid can be alleviated. In addition, the RFID tag 100 can alleviate the electrical coupling with the liquid by combining a plurality of antenna elements having different shapes.

[0105] In addition, according to the RFID tag 100 of the present embodiment, by combining a plurality of elements having different electrical lengths, the deviation of the resonance condition is corrected, and a good matching circuit with respect to the wavelength shortening effect of the liquid can be obtained.

[0106] According to the RFID tag 100 of the present embodiment, by combining a plurality of antenna elements having different shapes, or by combining a plurality of elements having different electrical lengths, the reception strength of the electric wave at the antenna portion 30 can be improved.

[0107] Note that the RFID tag 100 of the present embodiment can also be configured as follows. The same reference numerals are given to the same parts as the RFID tag 100, and the description thereof is omitted, and the different parts are described.

[0108] Figure 19D is a view showing a configuration example of the RFID tag 100-1 of the first modification example. The RFID tag 100-1 is configured so that the distance in the Y-axis direction from the first element 1 to the second element 2 is longer. In the RFID tag 100-1, if the gap between the first element 1 and the second element 2 is set to a value of, for example, 2.0 mm to 5.0 mm, it is preferable in terms of easily obtaining the complex conjugate of the antenna and the IC chip. If the gap between the first element 1 and the second element 2 is 5.0 mm or more, the resistance of the antenna becomes large, and the communication distance can become short.

[0109] Figure 19A is a view showing the impedance characteristics of the RFID tag 100-1 measured in a state in which the liquid 200 is not contained in the container 300. Figure 20A is a view showing the impedance characteristics of the RFID tag 100-1 measured in a state in which the liquid 200 is contained in the container 300.

[0110] In Figure 19A , the real number value at 920 MHz is about 10 Ω, and the imaginary number value at 920 MHz is about 177 Ω. In Figure 20A , the real number value at 920 MHz is about 23 Ω, and the imaginary number value at 920 MHz is about 196 Ω. According to Figure 20B and Figure 19B , it is found that the impedance characteristics of the RFID tag 100-1 are less disturbed compared to the impedance characteristics of the aforementioned comparative example 100A.

[0111] According to the RFID tag 100-1, the same effects as the RFID tag 100 can be obtained. In addition, according to the RFID tag 100-1, for example, even in a case where the up-and-down width of the first element 1 is not uniform due to a manufacturing tolerance of the meandering shape, by expanding the gap between the first element 1 and the second element 2, it is possible to suppress the contact of the first element 1 to the second element 2. Therefore, it is not necessary to manage the manufacturing tolerance of the first element 1 or the like. In addition, by expanding the gap between the first element 1 and the second element 2, the manufacturing of each wiring pattern becomes easy. As a result, the yield of the RFID tag 100-1 is improved, and it is possible to reduce the manufacturing cost.

[0112] Figure 20B is a view showing a configuration example of an RFID tag 100-2 which is a second modification example. The RFID tag 100-2 omits the first element 1 compared to the RFID tag 100. The electrical length of each element is set as follows.

[0113] For example, the length of the second element 2 is set to an electrical length which is a multiple of λ / 4 of the wavelength of the use frequency. In this case, the length of the third element 3 is set to an electrical length which is different from the electrical length which is a multiple of λ / 4. The different electrical length is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the use frequency.

[0114] Note that, instead of the second element 2, the electrical length of the third element 3 can be set to a multiple of λ / 4 of the wavelength of the use frequency. In this case, the length of the second element 2 is set to an electrical length which is different from the electrical length which is a multiple of λ / 4. The different electrical length is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the use frequency.

[0115] In addition, instead of the second element 2, the electrical length of the third element 3 and the electrical length of the fourth element 4 (for example, any one of the three fourth elements 4) can be set to a multiple of λ / 4 of the wavelength of the use frequency. In this case, the electrical length of the second element 2 is set to an electrical length which is different from the electrical length which is a multiple of λ / 4 of the wavelength of the use frequency. The different electrical length in this case is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the use frequency.

[0116] Figure 20C is a view showing the impedance characteristics of the RFID tag 100-2 measured in a state where the container 300 does not contain the liquid 200. Figure 19C is a view showing the impedance characteristics of the RFID tag 100-2 measured in a state where the container 300 contains the liquid 200.

[0117] In Figure 20CIn this context, the real value of 920MHz is approximately 11Ω, and the imaginary value is approximately 185Ω. Figure 20B In this context, the real value of 920MHz is approximately 16Ω, and the imaginary value is approximately 196Ω. According to... Figure 20D as well as Figure 19D It can be seen that the impedance characteristics of RFID tag 100-2 are less disordered compared with the impedance characteristics of the aforementioned comparative example 100A.

[0118] According to RFID tag 100-2, by combining multiple components that differ in electrical length and shape, the same effect as RFID tag 100 can be achieved.

[0119] Furthermore, according to RFID tag 100-2, since the first element 1 is not required, not only is the management of manufacturing tolerances for the first element 1 unnecessary, but the construction is also simplified. As a result, the yield of RFID tag 100-2 is improved, and manufacturing costs can be further reduced.

[0120] Figure 20D This is a diagram showing a configuration example of the third modified RFID tag 100-3. The RFID tag 100-3 has fewer fourth elements 4 compared to the RFID tag 100-2.

[0121] Figure 21 This is a graph showing the impedance characteristics of the RFID tag 100-3 measured in a container 300 without liquid 200. Figure 8 This is a diagram showing the impedance characteristics of an RFID tag 100-3 measured in a container 300 containing liquid 200.

[0122] exist ​ In this context, the real value of 920MHz is approximately 11Ω, and the imaginary value is approximately 184Ω. ​ In this context, the real value of 920MHz is approximately 17Ω, and the imaginary value is approximately 196Ω. According to... ​ as well as ​ It can be seen that the impedance characteristics of RFID tag 100-3 are less disordered compared to the impedance characteristics of the aforementioned comparative example 100A. Furthermore, according to... ​ as well as ​ It can be seen that the impedance characteristics of RFID tag 100-3 are not significantly disrupted compared to the impedance characteristics of RFID tag 100-2 in the aforementioned second variation.

[0123] According to RFID tag 100-3, by combining multiple components that differ in electrical length and shape, the same effect as RFID tag 100 can be achieved.

[0124] Further, according to the RFID tag 100-3, for example, in correspondence with being able to reduce the number of the fourth elements 4, not only management of manufacturing tolerances is not required, but also the configuration is simplified. As a result, the yield of the RFID tag 100-3 is improved, and the manufacturing cost can be further reduced.

[0125] ​ is a view showing a configuration example of the RFID tag 100-4 of a fourth modification example. The RFID tag 100-4 uses a fifth element 5 instead of the third element 3 and the fourth element 4 compared to the RFID tag 100-3. The second element 2 is a main portion, and the fifth element 5 is a sub portion.

[0126] The fifth element 5 is a conductor that is connected to the second element 2 in a manner of branching from the second element 2 halfway, and extends in parallel with the second element 2. The fifth element 5 is a branched element.

[0127] The connection point of the fifth element 5 to the second element 2 is, for example, a position that is apart from the connection point of the second element 2 and the loop conductor 20 by a prescribed distance. If the prescribed distance is set to a value of, for example, 5.0 mm to 100.0 mm, the resistance of the antenna does not become excessively large, and thus is preferable.

[0128] A gap is formed between the second element 2 and the fifth element 5 in a portion that extends in a direction opposite to the loop conductor 20 side. If the gap (separation distance in the Y-axis direction) is set to a value of, for example, 1.0 mm to 30.0 mm, the resistance of the antenna does not become excessively large, and thus is preferable. Note that the aforementioned fourth element 4 can be provided in the gap.

[0129] The electrical length of each element is set as follows.

[0130] For example, the length of the second element 2 is set to an electrical length that is a multiple of λ / 4 of the wavelength of the frequency of use. In this case, the length of the fifth element 5 is set to an electrical length that is different from the electrical length that is a multiple of λ / 4. The different electrical length is, for example, in a range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0131] Further, the electrical length of the fifth element 5 can be set to a multiple of λ / 4 of the wavelength of the frequency of use instead of the second element 2. In this case, the electrical length of the second element 2 is set to an electrical length that is different from the electrical length that is a multiple of λ / 4 of the wavelength of the frequency of use. The different electrical length in this case is, for example, in a range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0132] ​ is a view showing the impedance characteristics of the RFID tag 100-4 measured in a state in which the container 300 does not contain the liquid 200. ​is a graph showing the impedance characteristics of the RFID tag 100-4 measured in a state in which the container 300 contains the liquid 200.

[0133] In ​ , the real number value at 920 MHz is about 9 Ω, and the imaginary number value at 920 MHz is about 184 Ω. In ​ , the real number value at 920 MHz is about 16 Ω, and the imaginary number value at 920 MHz is about 193 Ω. According to ​ and ​ , it is known that the impedance characteristics of the RFID tag 100-4 are less disturbed than the impedance characteristics of the aforementioned comparative example 100A. In addition, according to ​ and ​ , it is known that the impedance characteristics of the RFID tag 100-4 are substantially the same as the impedance characteristics of the RFID tag 100-3 of the aforementioned third modification example, and do not produce a large disturbance.

[0134] According to the RFID tag 100-4, the same effects as the RFID tag 100 can be obtained by combining a plurality of elements different in both the electrical length and the shape.

[0135] In addition, according to the RFID tag 100-4, the fourth element 4 can be omitted, and accordingly not only management of manufacturing tolerances is not required, but also the configuration is simplified. As a result, the yield of the RFID tag 100-4 is improved, and the manufacturing cost can be further reduced.

[0136] In addition, according to the RFID tag 100-4, since it is a configuration in which the branching position of the fifth element 5, that is, the lead-out position of the fifth element 5 from the second element 2 is easily adjusted, the design conditions of the RFID tag 100-4 can have degrees of freedom. For example, in the case of a special-shaped container 300 in which the surface area of the RFID tag 100-4 must be made as small as possible, it is expected that the area of the lower side (negative Y-axis direction side) of the second element 2 becomes narrow. Even in this case, by making the length of the portion of the fifth element 5 extending in the X-axis direction shorter on the basis of making the branching position of the fifth element 5 close to the loop-shaped conductor 20 as much as possible, it is possible to be applied to the special container 300. Therefore, since the containers 300 to which the RFID tag 100-4 can be applied increase, the yield of the RFID tag 100-4 can be increased, and the manufacturing unit price of the RFID tag 100-4 can be further reduced.

[0137] ​is a view showing a configuration example of an RFID label 100-5 of a fifth modification. The RFID label 100-5 omits the fifth element 5 compared to the RFID label 100-4. The RFID label 100-5 has a simple configuration including the second element 2 instead of a configuration in which a plurality of elements different in both the electrical length and the shape are combined.

[0138] The second element 2 of the RFID label 100-5 is a straight conductor having an electrical length set to a multiple of approximately 1 / 4 of the wavelength of the frequency of use.

[0139] The present inventors confirmed that the impedance characteristic of the RFID label 100-5 is an impedance characteristic equivalent to, for example, the impedance characteristic shown in ​ and ​ In addition, the present inventors also confirmed that the impedance characteristic of the RFID label 100-5 is less disturbed compared to the impedance characteristic of the aforementioned comparative example 100A.

[0140] In addition, although the communication distance with the reader based on the RFID label 100-5 has a tendency to be shorter compared to the communication distance with the reader based on the RFID labels 100 to 100-4, it was confirmed that at least a practical communication distance (for example, about 1 m to 7 m) can be ensured. Note that even in the case where the communication distance is shortened, by, for example, disposing a reader at a conveyor belt for carrying containers, it is possible to read the identification information, and thus it is possible to apply to inventory management of various goods and the like.

[0141] The reason why such an impedance characteristic is excellent is that by setting the antenna element to a straight shape, the electrical coupling between the antenna element and the liquid is weakened compared to the case where only a meandering-shaped antenna element is used.

[0142] In the past, in order to ensure the electrical length necessary for wireless communication of the antenna portion 30, cases where a meandering-shaped antenna element, a ring-shaped antenna element, or the like is used are more common. However, if such an antenna element is used, the electrical coupling with the liquid becomes strong, and the impedance characteristic is greatly disturbed, and thus it is not possible to ensure the desired antenna performance. Therefore, in the past, measures such as making the distance from the antenna element to the liquid large by providing a partition between the antenna element and the container to reduce the electrical coupling, and reducing the electrical coupling by inserting a metal sheet between the antenna element and the container were taken.

[0143] According to the RFID label 100-5 of the fifth modification, since such measures are not necessary, the management of the manufacturing of the RFID label 100-5 becomes easy, and it is possible to greatly reduce the materials necessary for the manufacturing of the RFID label 100-5. Therefore, it is possible to achieve a great reduction in the manufacturing cost of the RFID label 100-5.

[0144] ​ is a view showing a configuration example of an RFID label 100-6 of a sixth modification. The RFID label 100-6 omits the fourth element 4 compared with the RFID label 100-3 of the third modification.

[0145] The inventors of the present application confirmed that the impedance characteristic of the RFID label 100-6 is less disturbed compared with the impedance characteristic of the aforementioned comparative example 100A. In addition, it was confirmed that the communication distance with the reader based on the RFID label 100-6 and the communication distance with the reader based on the RFID label 100-3 are equivalent distances.

[0146] According to the RFID label 100-6, for example, the fourth element 4 can be omitted, and accordingly not only management of manufacturing tolerances is not needed, but also the configuration is simplified. As a result, the yield of the RFID label 100-6 is improved, and the manufacturing cost can be further reduced.

[0147] ​ is a view showing a configuration example of an RFID label 100-7 of a seventh modification. The RFID label 100-7 omits the third element 3 and the fourth element 4 compared with the RFID label 100. In a case where the first element 1 is the main portion, the second element 2 is the sub portion, and in a case where the second element 2 is the main portion, the first element 1 is the sub portion.

[0148] The electrical length of each element is set as follows.

[0149] For example, the length of the first element 1 is set to an electrical length of a multiple of λ / 4 of the wavelength of the frequency of use. In this case, the length of the second element 2 is set to an electrical length different from the electrical length of the multiple of λ / 4. The different electrical length is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0150] Note that the electrical length of the second element 2 can be set to a multiple of λ / 4 of the wavelength of the frequency of use instead of the first element 1. In this case, the electrical length of the first element 1 is set to an electrical length different from the electrical length of the multiple of λ / 4 of the wavelength of the frequency of use. The different electrical length in this case is, for example, in the range of λ / 3.5 to λ / 4.5 of the wavelength of the frequency of use.

[0151] The inventors of the present application confirmed that the impedance characteristic of the RFID label 100-7 is less disturbed compared with the impedance characteristic of the aforementioned comparative example 100A. In addition, it was confirmed that the communication distance with the reader based on the RFID label 100-7 and the communication distance with the reader based on the RFID label 100 are equivalent distances.

[0152] According to the RFID tag 100-7, for example, the third element 3 and the fourth element 4 can be omitted, and accordingly not only management of manufacturing tolerances is not required, but also the configuration is simplified. As a result, the yield of the RFID tag 100-7 is improved, and the manufacturing cost can be further reduced.

[0153] ​ is a drawing showing a configuration example of an RFID tag 100-8 of an eighth modification example. The RFID tag 100-8 uses a fifth element 5 instead of the third element 3 and the fourth element 4, compared with the RFID tag 100. In a case where the first element 1 is a main portion, the second element 2 is a sub portion, and in a case where the second element 2 is a main portion, the first element 1 is a sub portion.

[0154] The electrical length of each element is set as follows.

[0155] For example, in a case where the length of the first element 1 is set to an electrical length of a multiple of λ / 4 of the wavelength of the use frequency, at least one of the length of the second element 2 and the length of the fifth element 5 is set to an electrical length different from the electrical length of the multiple of λ / 4. The different electrical length is, for example, in a range of λ / 3.5 to λ / 4.5 of the wavelength of the use frequency.

[0156] In addition, in a case where the length of the second element 2 is set to an electrical length of a multiple of λ / 4 of the wavelength of the use frequency, at least one of the length of the first element 1 and the length of the fifth element 5 is set to an electrical length different from the electrical length of the multiple of λ / 4. The different electrical length is, for example, in a range of λ / 3.5 to λ / 4.5 of the wavelength of the use frequency.

[0157] In addition, in a case where the electrical length of the fifth element 5 is set to a multiple of λ / 4 of the wavelength of the use frequency, at least one of the electrical length of the first element 1 and the length of the second element 2 is set to an electrical length different from the electrical length of the multiple of λ / 4. The different electrical length is, for example, in a range of λ / 3.5 to λ / 4.5 of the wavelength of the use frequency.

[0158] The present inventors confirmed that the impedance characteristic of the RFID tag 100-8 is less disturbed compared with the impedance characteristic of the aforementioned comparative example 100A. In addition, it was also confirmed that the communication distance with the reader based on the RFID tag 100-8 and the communication distance with the reader based on the RFID tag 100 are equivalent distances.

[0159] According to the RFID tag 100-8, for example, the fourth element 4 can be omitted, and accordingly not only management of manufacturing tolerances is not required, but also the configuration is simplified. As a result, the yield of the RFID tag 100-8 is improved, and the manufacturing cost can be further reduced.

[0160] Note that each of the RFID tags 100 to 100-8 of the present embodiment can be applied to not only an electric wave of the UHF band but also an electric wave of the VHF band, the SHF band, or the like. In a case where the frequency of use of the RFID tags 100 to 100-8 is a frequency of the UHF band, such as 860 to 960 MHz, 915 to 925 MHz, or the like, since the UHF band has a higher frequency than the VHF band, the wavelength is shorter, and this is advantageous for miniaturization of the antenna. Therefore, by setting the RFID tags 100 to 100-8 of the present embodiment to a shape suitable for an electric wave of the UHF band, miniaturization of the IC chip 10 can be achieved, and a wireless tag that is also small in memory capacity and inexpensive can be obtained.

[0161] In addition, each of the RFID tags 100 to 100-8 of the present embodiment can be applied to either of a wireless tag of an electromagnetic induction type and a wireless tag of an electric wave type. In particular, in a case where each of the RFID tags 100 to 100-8 is applied to a wireless tag of an electric wave type, a prescribed wireless communication distance from a reader can be ensured. The prescribed wireless communication distance is, for example, a range of 0 m to 20 m.

[0162] Note that, with the RFID tags 100 to 100-8 of the present embodiment, wireless communication using an electric wave of the UHF band, the VHF band, the SHF band, or the like can be performed regardless of whether the surrounding in which the RFID tags 100 to 100-8 exist is air (atmosphere) or water. For example, in a case where the container 300 having the RFID tags 100 to 100-8 is housed in a bucket or the like, wireless communication with a reader using the RFID tags 100 to 100-8 can be performed regardless of whether the bucket is filled with water or not. Hereinafter, with an RFID tag 100-9 of a ninth modification example having technical features common to the RFID tags 100 to 100-8, wireless communication that can be performed regardless of whether the RFID tag 100-9 is disposed in air or water will be described.

[0163] ​ FIG. 1 is a first graph showing a frequency characteristic of an RFID tag disposed in air. ​ FIG. 2 is a second graph showing a frequency characteristic of an RFID tag disposed in air. ​ FIG. 3 is a third graph showing a frequency characteristic of an RFID tag disposed in air. ​ FIG. 4 is a fourth graph showing a frequency characteristic of an RFID tag disposed in air. ​ FIG. 5 is a fifth graph showing a frequency characteristic of an RFID tag disposed in air.

[0164] ​In FIG. 10, the frequency characteristics of the RFID tag 100-9 provided in air are shown. The horizontal axis of each graph indicates the frequency of the electric wave for wireless communication, and the vertical axis indicates the possible distance of communication from the RFID tag 100-9 to the reader. Note that the detailed configuration of the RFID tag 100-9 will be described later.

[0165] In ​ In FIG. 11, the data of the RFID tag 100-9 provided in a 500-ml plastic bottle (not frozen) containing a liquid are shown. According to ​ In the case of the 500-ml plastic bottle, it is known that as the frequency band of the resonance frequency when the possible distance of communication is set to 10 cm or more, 830 MHz to 1040 MHz can be ensured relatively widely.

[0166] In ​ In FIG. 12, the data of the RFID tag 100-9 provided in a 900-ml glass bottle containing alcohol (for example, 25% ethanol added to water) are shown. According to ​ In the case of the 900-ml glass bottle, it is known that as the frequency band of the resonance frequency when the possible distance of communication is set to 10 cm or more, 740 MHz to 1200 MHz can be ensured, for example.

[0167] In ​ In FIG. 13, the data of the RFID tag 100-9 provided in a 1000-ml paper bag containing water are shown. According to ​ In the case of the 1000-ml paper bag, it is known that as the frequency band of the resonance frequency when the possible distance of communication is set to 10 cm or more, 780 MHz to 1200 MHz can be ensured, for example.

[0168] In ​ In FIG. 14, the data of the RFID tag 100-9 provided in a 1500-ml plastic bottle containing oil (Nobil Oil salad oil) are shown. According to ​ In the case of the 1500-ml plastic bottle, it is known that as the frequency band of the resonance frequency when the possible distance of communication is set to 10 cm or more, 700 MHz to 1200 MHz can be ensured, for example.

[0169] In ​ In FIG. 15, the data of the RFID tag 100-9 provided in a 500-ml plastic bottle (frozen) containing a liquid are shown. According to ​ In the case of the frozen plastic bottle, it is known that as the frequency band of the resonance frequency when the possible distance of communication is set to 10 cm or more, 700 MHz to 1200 MHz can be ensured, for example.

[0170] Next, with reference to ​The frequency characteristics before and after a 500-ml plastic bottle provided with the RFID tag 100-9 is placed in a water bucket and water is poured into the water bucket are described.

[0171] ​ is a first graph for describing the frequency characteristics of the RFID tag which can be provided in either of air and water. ​ is a second graph for describing the frequency characteristics of the RFID tag which can be provided in either of air and water. ​ is a third graph for describing the frequency characteristics of the RFID tag which can be provided in either of air and water. ​ is a fourth graph for describing the frequency characteristics of the RFID tag which can be provided in either of air and water.

[0172] As shown in ​ , in a water bucket (container 400) capable of containing water 311, a plastic bottle (container 300) of, for example, 500 ml is contained. ​ represents a state in which the container 400 is not filled with water 311, ​ represents a state in which the container 400 is filled with water 311.

[0173] In order of ​ , ​ , ​ , the amount of water 311 is increased. The state of ​ is a state in which the RFID tag 100-9 is about to be immersed in water, that is, a state in which most of the container 300 is submerged in the water 311, but the RFID tag 100-9 is not submerged in the water 311. The state of ​ is a state after the RFID tag 100-9 is just immersed in water, that is, a state in which there is a little water 311 on the upper surface of the RFID tag 100-9. The state in which there is a little water 311 means, for example, that the distance from the surface of the RFID tag 100-9 to the water surface 311a is about 1 mm to 1 cm. The state of ​ is a state in which the amount of water 311 is increased compared to the state of ​ , for example, the distance of the RFID tag 100-9 to the water surface 311a becomes about 15 cm.

[0174] The frequency characteristics of the RFID tag 100-9 to be verified in these states are shown in ​ . ​ is a graph showing the frequency characteristics of the RFID tag shown in ​ , ​ is a graph showing the frequency characteristics of the RFID tag shown in ​ , ​ is a graph showing the frequency characteristics of the RFID tag shown in ​Figures showing frequency characteristics of the RFID tag shown in ​ Figures showing frequency characteristics of the RFID tag shown in ​ Figures showing frequency characteristics of the RFID tag shown in ​ need to be noted that, as shown in

[0175] ​ the frequency characteristics of the RFID tag 100-9 correspond to the state of the container 400. According to ​ , it is known that in the state where the container 400 is not filled with water 311, a frequency band of the resonance frequency when the communication possible distance is set to 10 cm or more can be ensured widely from 800 MHz to 1200 MHz. ​

[0176] ​ the frequency characteristics of the RFID tag 100-9 correspond to the state of the container 400. According to ​ , it is known that in the state where the RFID tag 100-9 is not immersed in water 311, a frequency band of the resonance frequency when the communication possible distance is set to 10 cm or more can be ensured widely from 800 MHz to 1200 MHz. ​

[0177] ​ the frequency characteristics of the RFID tag 100-9 correspond to the state of the container 400. According to ​ , it is known that in the state where the RFID tag 100-9 is slightly immersed in water 311, although the communication possible distance is shorter as a whole compared to the data of ​ , the communication possible distance can be ensured widely except for the vicinity of 840 MHz and the vicinity of 1100 MHz. ​

[0178] ​ the frequency characteristics of the RFID tag 100-9 correspond to the state of the container 400. According to ​ , it is known that even in the case where the distance from the RFID tag 100-9 to the water surface 311a is long, the communication possible distance can be ensured widely. ​ need to be noted that, although the data is not exemplified in the present embodiment, in the case where the distance from the RFID tag 100-9 to the water surface 311a is longer than 15 cm, for example, the distance is up to about 30 cm, it has been confirmed that the wireless communication using the RFID tag 100-9 is possible.

[0179]

[0180] ​ is a figure showing a configuration example of the RFID tag 100-9 of the ninth modified example. The RFID tag 100-9 of the ninth modified example is different from the RFID tag 100-9 of the eighth modified example in that​​​​​ The difference between the RFID tag 100-2 shown is that the number of fourth elements 4 is increased in the RFID tag 100-9.

[0181] According to RFID tag 100-9, the electrical coupling between the antenna element and the liquid can be mitigated. Furthermore, according to RFID tag 100-9, by combining multiple elements with different electrical lengths, the deviation of the resonance condition is corrected, and a good matching circuit can be obtained with the wavelength shortening effect relative to the liquid. Additionally, according to RFID tag 100-9, by combining multiple elements with different electrical lengths, the reception strength of radio waves at the antenna section 30 can be improved. In particular, due to the increase in the number of fourth elements 4, the reception strength of radio waves at the antenna section 30 can be further improved in applications involving water. Furthermore, according to RFID tag 100-9, based on its application in air, for example, in a store, even when plastic bottles are immersed in containers filled with ice water for cooling, inventory management is possible. Therefore, the hassle of removing plastic bottles from containers filled with ice water and checking inventory counts can be eliminated. Furthermore, even if plastic bottles are submerged in water due to earthquakes, floods, etc., inventory counts can be checked while the bottles are submerged.

[0182] The configuration shown in the above embodiments is an example illustrating the content of the present invention. It can be combined with other known technologies, and some parts of the configuration can be omitted or changed without departing from the scope of the present invention.

[0183] This international application claims priority based on Japanese Patent Application No. 2019-134033, filed July 19, 2019, and Japanese Patent Application No. 2019-195734, filed October 28, 2019, the entire contents of which are incorporated herein by reference.

[0184] Explanation of reference numerals in the attached figures

[0185] 1: First element

[0186] 2: Second element

[0187] 3: Third element

[0188] 4: Fourth Component

[0189] 5: Fifth Element

[0190] 10: IC chips

[0191] 20: Ring conductor

[0192] 30: Antenna section

[0193] 30A: conductor portion

[0194] 30B: conductor portion

[0195] 31: element

[0196] 40: sheet

[0197] 100: RFID label

[0198] 100-1: RFID label

[0199] 100-2: RFID label

[0200] 100-3: RFID label

[0201] 100-4: RFID label

[0202] 100-5: RFID label

[0203] 100-6: RFID label

[0204] 100-7: RFID label

[0205] 100-8: RFID label

[0206] 100-9: RFID label

[0207] 200: liquid

[0208] 300: container

[0209] 301: cap portion

[0210] 302: label

Claims

1. An RFID label provided on a surface of a container for containing a liquid, the RFID label comprising: an IC chip for recording identification information; a loop-shaped conductor connected to the IC chip; and an antenna portion having a pair of lattice-shaped conductors connected to the loop-shaped conductor and extending from the loop-shaped conductor in directions away from each other, each of the pair of lattice-shaped conductors includes: a straight line element as a straight line-shaped conductor connected to the loop-shaped conductor and extending in a direction away from the loop-shaped conductor; a hook element as a hook-shaped conductor provided at a tip of the straight line element and bent from the tip of the straight line element to a side opposite to a direction in which the straight line element extends and extending toward the loop-shaped conductor; and a lattice element as a straight line-shaped conductor extending from the straight line element toward the hook element and connecting the straight line element and the hook element, an electrical length of the antenna portion is set in the following manner: the straight line element is set to an electrical length of a multiple of 1 / 4 of a wavelength of a frequency of use, the hook element is set to an electrical length different from the electrical length of the multiple of 1 / 4 of the wavelength of the frequency of use, or the hook element is set to an electrical length of a multiple of 1 / 4 of a wavelength of a frequency of use, the straight line element is set to an electrical length different from the electrical length of the multiple of 1 / 4 of the wavelength of the frequency of use, or a total of the hook element and the lattice element is set to an electrical length of a multiple of 1 / 4 of a wavelength of a frequency of use, the straight line element is set to an electrical length different from the electrical length of the multiple of 1 / 4 of the wavelength of the frequency of use.

2. An RFID label provided on a surface of a container for containing a liquid, the RFID label comprising: an IC chip for recording identification information; a loop-shaped conductor connected to the IC chip; and an antenna portion having a pair of meander elements as meander-shaped conductors connected to the loop-shaped conductor and extending in a predetermined direction from the loop-shaped conductor in a manner away from each other and a pair of lattice-shaped conductors extending in the predetermined direction in a manner away from each other, each of the pair of lattice-shaped conductors includes: a straight line element as a straight line-shaped conductor connected to the meander element in a manner branching from a middle of the meander element and extending in the predetermined direction; a hook element as a hook-shaped conductor provided at a tip of the straight line element and bent from the tip of the straight line element to a side opposite to a direction in which the straight line element extends and extending toward the loop-shaped conductor; and a lattice element as a straight line-shaped conductor extending from the straight line element toward the hook element and connecting the straight line element and the hook element, an electrical length of the antenna portion is set in the following manner: ​ ​ the straight element and the hook element are set to an electrical length different from the electrical length of the multiple of 1 / 4 of the wavelength of the use frequency, or the straight element and the hook element are set to an electrical length different from the electrical length of the multiple of 1 / 4 of the wavelength of the use frequency, or the straight element and the hook element are set to an electrical length different from the electrical length of the multiple of 1 / 4 of the wavelength of the use frequency, or the straight element and the hook element are set to an electrical length different from the electrical length of the multiple of 1 / 4 of the wavelength of the use frequency, or 3. The RFID label according to claim 1 or 2, wherein the use frequency is a frequency of 860 MHz to 960 MHz in the UHF band.

4. The RFID label according to claim 1 or 2, wherein the RFID label is a wireless label of the electric wave type.

5. The RFID label according to claim 1 or 2, wherein the RFID label is disposed in air.

6. The RFID label according to claim 1 or 2, wherein the RFID label can be disposed in either air or water.

7. The RFID label according to claim 1 or 2, wherein the RFID label is disposed in water.

8. The RFID label according to claim 1 or 2, wherein the use frequency is a frequency of 915 MHz to 925 MHz in the UHF band.

9. The RFID label according to claim 1 or 2, wherein the liquid is any one of water, oil, and alcohol.

10. The RFID label according to claim 1 or 2, wherein the liquid is any mixture of water, oil, and alcohol.

11. A plastic bottle to which the RFID label according to any one of claims 1 to 10 is attached.

12. An antenna for the RFID label according to any one of claims 1 to 10.

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