JP7340175B2 - RFID tags, plastic bottles, and antennas - Google Patents

Description

The present invention relates to an RFID (Radio Frequency Identification) module, a plastic bottle, and an antenna.

RFID labels affixed to adherends have become popular for logistics management and product management. An RFID label is a label with an RFID tag. The RFID tag includes an IC chip and an antenna electrically connected to the IC chip. The RFID tag is also called a wireless tag, an IC tag, an RF-ID tag, or an RF tag. If the adherend to which such an RFID label is affixed is a container containing liquid, such as a PET bottle for beverages, reading of identification information may be hindered. This is thought to be due to the fact that when the antenna is near a liquid, the characteristics of the antenna change due to the influence of the liquid, and the radio waves are absorbed by the liquid.

Patent Document 1 discloses an RFID label that can read identification information satisfactorily even when an adherend contains a liquid that may affect the reading of identification information. The RFID label disclosed in Patent Document 1 has a structure in which an antenna protrudes from an adherend. This increases the distance from the antenna to the liquid and reduces the above-mentioned effects, so that the identification information stored on the RFID label can be read out with ease.

JP2006-277524A

However, the conventional technology disclosed in Patent Document 1 has a structure in which the antenna protrudes from the adherend, so there is a risk of problems such as damage to the antenna when storing or transporting the container, and there is still room for improvement. be.

The present invention has been made in view of the above, and an object of the present invention is to obtain an RFID tag that can read identification information without causing problems such as damage to the antenna due to handling of the container.

In order to solve the above problems, an RFID tag according to the present invention includes an IC chip on which identification information is recorded, a loop-shaped conductor connected to the IC chip, and a loop-shaped conductor connected to the loop-shaped conductor and connected to the loop-shaped conductor. a pair of meander elements, each of which is a meander-shaped conductor, extending in a predetermined direction away from the shaped conductor; and a pair of lattice-shaped conductors extending in the predetermined direction, away from each other . , comprising;
Each of the pair of lattice-shaped conductors is connected to the meander element so as to branch from the middle of the meander element, and has a linear element that is a linear conductor extending in the predetermined direction, and a linear element at the tip of the linear element. a hook-shaped conductor that is provided and bent in a direction opposite to the direction in which the linear element extends from the tip of the linear element and extends toward the loop-shaped conductor; and a hook-shaped conductor that extends from the linear element toward the hook element. a lattice element that is an extending linear conductor and connects the linear element and the hook element;
(i) The meander element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency, and at least one of the linear element and the hook element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency. The electrical length is set to be different from the electrical length,
(ii) The linear element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency, and at least one of the meander element and the hook element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency. The electrical length is set to be different from the electrical length,
(iii) The total of the straight line element and the hook element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency, and the meander element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency. is set to have an electrical length different from the electrical length, or
(iv) The total electrical length of the linear element, the hook element, and the grating element is set to be a multiple of 1/4 of the wavelength of the used frequency, and the meander element is set to be 1/4 of the wavelength of the used frequency. The electrical length is set to be different from the electrical length that is a multiple of 4.

According to the present invention, it is possible to read the identification information without causing problems such as damage to the antenna due to handling of the container.

A perspective view of a container 300 for liquid 200 provided with an RFID tag 100 according to an embodiment of the present invention A diagram showing an example of the configuration of an RFID tag 100 A diagram showing the impedance characteristics of the RFID tag 100 measured when the liquid 200 is not contained in the container 300 A diagram showing the impedance characteristics of the RFID tag 100 measured when the liquid 200 is contained in the container 300 A diagram showing a configuration example of a comparative example 100A of the RFID tag 100 according to the embodiment of the present invention A diagram showing impedance characteristics of Comparative Example 100A measured when liquid 200 is not contained in container 300 A diagram showing impedance characteristics of Comparative Example 100A measured with liquid 200 contained in container 300 A diagram showing a configuration example of an RFID tag 100-1 according to a first modification A diagram showing the impedance characteristics of the RFID tag 100-1 measured when the liquid 200 is not contained in the container 300. A diagram showing the impedance characteristics of the RFID tag 100-1 measured when the liquid 200 is contained in the container 300. A diagram showing a configuration example of an RFID tag 100-2 according to a second modification A diagram showing the impedance characteristics of the RFID tag 100-2 measured when the liquid 200 is not contained in the container 300. A diagram showing the impedance characteristics of the RFID tag 100-2 measured when the liquid 200 is contained in the container 300. A diagram showing a configuration example of an RFID tag 100-3 according to a third modification A diagram showing the impedance characteristics of the RFID tag 100-3 measured when the liquid 200 is not contained in the container 300. A diagram showing the impedance characteristics of the RFID tag 100-3 measured when the liquid 200 is contained in the container 300. A diagram showing a configuration example of an RFID tag 100-4 according to a fourth modification A diagram showing the impedance characteristics of the RFID tag 100-4 measured when the liquid 200 is not contained in the container 300. A diagram showing the impedance characteristics of the RFID tag 100-4 measured when the liquid 200 is contained in the container 300. A diagram showing a configuration example of an RFID tag 100-5 according to a fifth modification. A diagram showing a configuration example of an RFID tag 100-6 according to a sixth modification A diagram showing a configuration example of an RFID tag 100-7 according to a seventh modification A diagram showing a configuration example of an RFID tag 100-8 according to an eighth modification Figure 1 shows the frequency characteristics of an RFID tag installed in the air Figure 2 shows the frequency characteristics of an RFID tag installed in the air Figure 3 showing the frequency characteristics of an RFID tag installed in the air Figure 4 shows the frequency characteristics of an RFID tag installed in the air Figure 5 shows the frequency characteristics of an RFID tag installed in the air Figure 1 for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water. Figure 2 for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water Figure 3 for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water Figure 4 for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water Diagram showing the frequency characteristics of the RFID tag shown in FIG. 19A Diagram showing the frequency characteristics of the RFID tag shown in FIG. 19B Diagram showing the frequency characteristics of the RFID tag shown in FIG. 19C Diagram showing the frequency characteristics of the RFID tag shown in FIG. 19D A diagram showing a configuration example of an RFID tag 100-9 according to a ninth modification

Embodiments of the present invention will be described in detail with reference to the drawings. In the following description, common parts in each figure may be given the same reference numerals and the description thereof will be omitted. Further, in order to facilitate understanding, the scale of each member in each drawing may be different from the actual scale. In each embodiment, deviations in parallel, right-angled, horizontal, vertical, up-down, left-right, etc. directions are allowed to an extent that does not impair the effects of the present invention. Moreover, the X-axis direction, the Y-axis direction, and the Z-axis direction 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, YZ plane, and ZX plane are, respectively, a virtual plane parallel to the X-axis direction and the Y-axis direction, a virtual plane parallel to the Y-axis direction and the Z-axis direction, and a virtual plane parallel to the Z-axis direction and the X-axis direction. represents. In FIG. 1 and subsequent figures, among the X-axis directions, the direction indicated by the arrow is the plus X-axis direction, and the opposite direction is the minus X-axis direction. Among the Y-axis directions, the direction indicated by the arrow is the positive Y-axis direction, and the direction opposite to this direction is the negative Y-axis direction. Among the Z-axis directions, the direction indicated by the arrow is the plus Z-axis direction, and the opposite direction is the minus Z-axis direction. The X-axis direction is equal to the height direction when the container, which will be described later, is viewed from the side. The Y-axis direction is equal to the width direction when the container, which will be described later, is viewed from the side. The Z-axis direction is equal to the depth direction when the container, which will be described later, is viewed from the side.

FIG. 1 is a perspective view of a container 300 containing a liquid 200 in which an RFID tag 100 according to an embodiment of the present invention is provided. The container 300 shown in FIG. 1 is a polyethylene terephthalate container (plastic bottle) in which the liquid 200 is contained. The liquid 200 is something similar to water, such as a soft drink or mineral water. Note that the liquid 200 is not limited to these, and may be oil, alcohol, or the like. Further, the liquid 200 may be a mixture of water, oil, alcohol, etc. (for example, a mixture of ethanol and water). A cap 301 is provided at the tip of the container 300 in the plus X-axis direction. A transparent band-shaped label 302 is placed on the outer peripheral surface of the container 300. An 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 in which the RFID tag 100 is provided is air.

Note that the container 300 may be any container that can contain the liquid 200, and may be, for example, a glass container or a closed container such as Tupperware (registered trademark). Below, in order to simplify the explanation, the liquid 200 may be simply referred to as a "liquid" and the container 300 may be simply referred to as a "container". Furthermore, since the RFID tag 100 is provided with a dipole antenna, the RFID tag 100 is attached to the container 300 in a vertically elongated manner, but the method of attaching the RFID tag 100 to the container 300 is limited to this. It's not a thing.

Next, a configuration example of the RFID tag 100 will be described using FIG. 2. FIG. 2 is a diagram showing an example of the configuration of the RFID tag 100. The RFID tag 100 includes a belt-shaped sheet 40, an IC chip 10 on which identification information is recorded, a loop-shaped conductor 20, and an antenna section 30.

The sheet 40 is a film formed into a band shape by laminating a plurality of synthetic resin films such as polyethylene terephthalate and polypropylene, for example. The IC chip 10, the loop-shaped conductor 20, and the antenna section 30 are arranged so as to be sandwiched between, for example, a plurality of laminated synthetic resin films. Note that the IC chip 10, the loop-shaped conductor 20, and the antenna section 30 may be provided directly on the container body, or may be provided on the label 302 of the container.

The IC chip 10 has an internal capacitance, and the inductance of the antenna section 30 and the internal capacitance of the IC chip 10 constitute a matching circuit.

The loop-shaped conductor 20 is a loop-shaped (annular) conductive wiring pattern that has one turn or less when the sheet 40 is viewed from above in the Z-axis direction.

The loop-shaped conductor 20 is electrically connected to the IC chip 10 and the antenna section 30. When the identification information recorded on the IC chip 10 is read by a reader, when the antenna unit 30 receives a UHF band radio wave, for example, a radio wave around 920 MHz, a current flows through the loop-shaped conductor 20 due to resonance. This generates an electromotive force that operates the IC chip 10. When the IC chip 10 operates, the identification information recorded on 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 a radio wave around 920 MHz as a carrier wave. Ru. The reader that receives this signal decodes the signal and forwards it to an external device. As described above, the RFID tag 100 of this embodiment is a passive radio wave type wireless tag that does not have a power source (battery) for holding and transmitting identification information. Therefore, compared to an active wireless tag that has a battery, it can be made smaller and lower in price since it does not have a battery.

The antenna section 30 is a dipole antenna configured to exhibit resonance characteristics with the IC chip 10 at the frequency of radio waves for wireless communication (for example, a frequency in the UHF band). The antenna section 30 has a total electrical length corresponding to around λ/2 (λ is the communication wavelength).

For example, the antenna unit 30 can respond to radio waves with a frequency around 920 MHz (for example, 860 MHz to 960 MHz, more preferably 915 MHz to 935 MHz) even when the container 300 is filled with liquid and there is liquid near the antenna. It has a structure that realizes impedance conjugate matching with the chip 10. The antenna section 30 includes two conductor sections (a conductor section 30A and a conductor section 30B) as a structure that realizes impedance conjugate matching with the IC chip 10. The conductor portion 30A and the conductor portion 30B are conductive wiring patterns connected to the loop conductor 20 and extending in directions away from the loop conductor 20. Conductive wiring patterns can be formed by existing methods such as pressing, etching, and plating of copper foil or aluminum foil, silk screen printing of metal paste, and metal wire. Formed.

The conductor portion 30A and the conductor portion 30B are formed line-symmetrically with respect to a virtual line VL passing approximately through the center of the IC chip 10. The virtual line VL is a line parallel to the XY plane and extending in the Y-axis direction. The virtual line VL is also a line that approximately bisects the RFID tag 100 into regions in the X-axis direction.

Each of the conductor portion 30A and the conductor portion 30B has an electrical length corresponding to around λ/4 (λ is the communication wavelength). The condition for impedance matching of the antenna section 30 is that the impedance when viewing the signal source from the load side and the impedance when viewing the load from the signal source side are complex conjugates of each other. Therefore, if the signal source impedance Zs from the load side is Zs=Rs+jXs, the maximum power is transmitted when the load impedance Zl is Zl=Rs-jXs.

Note that since the conductor portion 30A and the conductor portion 30B have a line-symmetrical shape with respect to the virtual line VL, the configuration of the conductor portion 30A will be described below. Regarding the configuration of the conductor portion 30B, the explanation thereof will be omitted by reversing the direction in which the conductor portion 30A extends in the X-axis direction.

The conductor section 30A includes a first element 1, a second element 2, a third element 3, and a fourth element 4.

The first element 1 is a meandering conductive wiring pattern extending from the loop-shaped conductor 20 in the minus X-axis direction. The first element 1 is a meander element.

The end of the first element 1 in the plus X-axis direction is connected to the loop-shaped conductor 20 . The connection point between the first element 1 and the loop-shaped conductor 20 is, for example, the peripheral edge of the loop-shaped conductor 20 on the plus Y-axis direction side. The first element 1 extends a certain distance from the connection point with the loop-shaped conductor 20 at a predetermined angle (for example, 30° to 60°) with respect to the minus X-axis direction, and extends from the point where it extends a certain distance in the minus X-axis direction. Stretch further. Note that the shape of the first element 1 is not limited to the illustrated example; for example, it extends a certain distance in the positive Y-axis direction from the connection point with the loop-shaped conductor 20, and bends perpendicularly from the point where it extends the certain distance to form the negative X-axis direction. The shape may be extended in the axial direction.

By connecting the first element 1 to the peripheral edge of the loop-shaped conductor 20 on the positive Y-axis direction side, the width of the entire antenna section 30 in the X-axis direction is narrowed, and the RFID tag has a small ratio of vertical width to horizontal width. 100 can be achieved. Therefore, for example, even when attaching the RFID tag 100 to a small-capacity plastic bottle with a relatively small height in the A tag 100 can be placed.

Note that the connection point between the first element 1 and the loop-shaped conductor 20 is not limited to this, and may be the peripheral edge of the loop-shaped conductor 20 in the minus X-axis direction. With this configuration, the first element 1 can be placed in the region of the loop-shaped conductor 20 on the minus X-axis direction side. Therefore, the width of the entire antenna section 30 in the Y-axis direction is narrowed, and an elongated RFID tag 100 can be realized. Therefore, even when attaching the RFID tag 100 to a large-capacity PET bottle with a relatively large height in the X-axis direction, for example, the RFID tag 100 can be placed in an area that does not interfere with the display of products, etc. on the PET bottle.

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

The end of the second element 2 in the plus X-axis direction is connected to the first element 1 or the loop-shaped conductor 20.

When the second element 2 is connected to the first element 1, the second element 2 is connected, for example, near the connection point between the first element 1 and the loop-shaped conductor 20. The second element 2 extends a certain distance from the connection point in the minus X-axis direction.

When the second element 2 is connected to the loop-shaped conductor 20, the second element 2 is connected, for example, to the peripheral edge of the loop-shaped conductor 20 on the plus Y-axis direction side.

The second element 2 may be provided on the minus Y-axis direction side of the first element 1, or may be provided on the plus Y-axis direction side of the first element 1.

As shown in FIG. 2, when the second element 2 is provided on the minus Y-axis direction side of the first element 1, the area on the minus X-axis direction side of the loop-shaped conductor 20 can be effectively utilized. Therefore, it is possible to realize an RFID tag 100 with a small ratio of vertical width to horizontal width.

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, the impedance of the antenna and the IC chip will be reduced. This is preferable in that complex conjugation can be easily obtained. If this distance becomes too large, the real part of the impedance becomes large, making it difficult to obtain a complex conjugate with the IC chip. The second element 2 is the main part, and the first element 1 is the sub part.

The third element 3 is a hook-shaped conductive wiring pattern that extends from the tip of the second element 2 in the minus X-axis direction 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 may be a U-shaped pattern or an L-shaped pattern.

Note that the second element 2 and the third element 3 may be integrally formed into a hook shape.

As shown in FIG. 2, the third element 3 extends a certain distance in the negative Y-axis direction from the tip of the second element 2 in the negative X-axis direction, and then bends perpendicularly to the positive Stretch a certain distance towards. This shape makes it possible to effectively utilize the region of the loop-shaped conductor 20 on the minus X-axis direction side. Therefore, it is possible to realize an RFID tag 100 with a small ratio of vertical width to horizontal width.

A gap is formed between a portion of the third element 3 extending toward the loop-shaped 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. A plurality of fourth elements 4 are provided in this gap.

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.

In this embodiment, three fourth elements 4 are used as an example, but the number of fourth elements 4 may be one or more. It is preferable that the interval in the X-axis direction between adjacent fourth elements 4 is set to a value from 1.0 mm to 30.0 mm, for example, since the communicable frequency band becomes wider and the communication distance increases.

The electrical length of each element is set as follows.

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 used. 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 different from an electrical length that is a multiple of λ/4 .

Note that instead of the first element 1, the electrical length of the second element 2 may be set to be a multiple of λ/4 of the wavelength of the frequency used. 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 used .

Also, instead of the first element 1, the sum of the electrical length of the second element 2 and the electrical length of the L-shaped (inverted L-shaped) third element 3 is λ/4 of the wavelength of the frequency used. may be set to a multiple of . In this case, the electrical length of the first element 1 is set to be different from the electrical length that is a multiple of λ/4 of the wavelength of the frequency used .

Also, instead of the first element 1, 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) The total electrical length may be set to a multiple of λ/4 of the wavelength of the frequency used. In this case, the electrical length of the first element 1 is set to be different from the electrical length that is a multiple of λ/4 of the wavelength of the frequency used .

Next, the impedance characteristics of the RFID tag 100 will be explained using FIGS. 3A and 3B.

FIG. 3A is a diagram showing the impedance characteristics of the RFID tag 100 measured when the liquid 200 is not contained in the container 300. FIG. 3B is a diagram showing the impedance characteristics of the RFID tag 100 measured while the liquid 200 is contained in the container 300.

The impedance Zc of the RFID tag 100 is assumed to be "Zc=Rc+jXc", and the vertical axis shows real and imaginary values. The subscript "c" is an abbreviation for chip (IC chip 10). The horizontal axis represents the frequency of radio waves for wireless communication. The solid line is a plot of real numbers corresponding to each frequency. The dash-dotted line is a plot of imaginary numbers corresponding to each frequency.

In FIG. 3A, the real value of 920 MHz is approximately 8Ω, and the imaginary value of 920 MHz is approximately 176Ω. In FIG. 3B, the real value of 920 MHz is approximately 21 Ω, and the imaginary value of 920 MHz is approximately 198 Ω. In this way, it can be seen that the impedance characteristics change depending on the presence or absence of liquid in the container.

The impedance characteristics shown in FIGS. 3A and 3B have less disturbance than the impedance characteristics of a comparative example described later. A small disturbance in impedance characteristics means a small deterioration in antenna performance. A comparative example of this embodiment will be described using FIG. 4.

FIG. 4 is a diagram showing a configuration example of a comparative example 100A of the RFID tag 100 according to the embodiment of the present invention. The comparative example 100A includes an element 31 having a meander-shaped wiring pattern instead of the first element 1, second element 2, and third element 3.

The element 31 is a rectangular conductive wiring pattern connected to the loop conductor 20 and extending from the loop conductor 20 in the X-axis direction. The element 31 is set to have an electrical length that is a multiple of 1/4 of the wavelength of the frequency used .

The impedance characteristics of the comparative example 100A configured in this way will be explained using FIGS. 5A and 5B.

FIG. 5A is a diagram showing the impedance characteristics of the comparative example 100A measured in a state where the liquid 200 is not contained in the container 300. FIG. 5B is a diagram showing the impedance characteristics of the comparative example 100A measured with the liquid 200 contained in the container 300. Similar to FIGS. 3A and 3B, the vertical axis indicates real and imaginary values. The horizontal axis represents the frequency of radio waves for wireless communication. The solid line is a plot of real numbers corresponding to each frequency. The dash-dotted line is an imaginary number plot corresponding to each frequency.

In FIG. 5A, the real value at 920 MHz is approximately 17Ω, and the imaginary value at 920 MHz is approximately 243Ω. In FIG. 5B, the real value at 920 MHz is approximately 80Ω, and the imaginary value at 920MHz is approximately 25Ω.

It can be seen that the impedance characteristics shown in FIGS. 5A and 5B are significantly disturbed compared to the impedance characteristics shown in FIGS. 3A and 3B. Electrical coupling between the meandering shape of the element 31 and the liquid having a dielectric constant ε of "80" is considered to be the cause of the large disturbance in the impedance characteristics. For example, if the element 31 is placed in front of the liquid when viewed from the leader, that is, if the leader, element 31, and liquid are arranged in this order, the impedance of Comparative Example 100A will be large due to the dielectric constant of the liquid. Change. That is, in the comparative example 100A, in order to ensure the electrical length necessary for wireless communication of the antenna unit 30, a meander-shaped antenna element is adopted, so that the electrical connection between the liquid on the back side of the element 31 and the antenna element as seen from the reader is It is assumed that the physical coupling becomes stronger and the impedance characteristics are greatly disturbed. To solve this problem, conventional methods have been to install a spacer between the antenna element and the container to increase the distance from the antenna element to the liquid and reduce electrical coupling. Measures were taken such as inserting sheets to reduce electrical coupling.

On the other hand, it is known that radio waves in the UHF band, which has a relatively high frequency, are easily absorbed by liquid. For example, if a liquid is present between the reader and the element 31, part of the radio waves transmitted from the reader will be absorbed by the liquid in the container, and the remaining weak radio waves will be received by the element 31. Ru. That is, the reception strength of the radio waves at the element 31 decreases. Since the element 31 uses this radio wave as a carrier wave to transmit a signal related to identification information to the reader, the weak radio wave transmitted from the comparative example 100A is absorbed by the liquid in the container, and the reader cannot receive the radio wave. Strength decreases.

Furthermore, it is known that when a liquid is present between the reader and the element 31, when the radio wave passes through the liquid, the wavelength of the radio wave becomes slightly shorter due to the wavelength shortening effect of the liquid. When the wavelength of the radio wave becomes shorter, the resonance condition between the antenna section 30 and the IC chip 10 is deviated from, and the conjugate matching condition is not satisfied, making it impossible to obtain the maximum power.

In the comparative example 100A, a meandering element 31 is used, and the electrical length of the element 31 is set to be a multiple of λ/4 of the wavelength of the frequency used. Therefore, the inventor of the present invention has discovered that wireless communication with a reader can become difficult due to the above-mentioned electrical coupling, wavelength shortening effect, radio wave absorption and attenuation, and the like.

On the other hand, the RFID tag 100 according to the present embodiment can reduce the electrical coupling between the antenna element and the liquid by using at least an antenna element having a shape other than the meander shape. Further, the RFID tag 100 can reduce electrical coupling between the antenna element and the liquid by combining a plurality of antenna elements having different shapes.

Furthermore, according to the RFID tag 100 according to the present embodiment, by combining a plurality of elements with different electrical lengths, deviations in resonance conditions can be corrected, and a matching circuit that is robust against the wavelength shortening effect of liquid can be obtained. .

According to the RFID tag 100 according to the present embodiment, the reception strength of radio waves at the antenna section 30 can be increased by combining a plurality of antenna elements with different shapes or a plurality of elements with different electrical lengths. I can do it.

Note that the RFID tag 100 according to this embodiment may be configured as follows. Parts that are the same as those in the RFID tag 100 are given the same reference numerals and explanations thereof will be omitted, and different parts will be described.

FIG. 6 is a diagram showing a configuration example of an RFID tag 100-1 according to a first modification. The RFID tag 100-1 is configured such that the distance from the first element 1 to the second element 2 in the Y-axis direction is wide. 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 becomes easier to obtain the complex conjugate of the antenna and the IC chip. This is preferable in this respect. If the gap between the first element 1 and the second element 2 is 5.0 mm or more, the resistance of the antenna will increase and there is a possibility that the communication distance will decrease.

FIG. 7A is a diagram showing the impedance characteristics of the RFID tag 100-1 measured when the liquid 200 is not contained in the container 300. FIG. 7B is a diagram showing the impedance characteristics of the RFID tag 100-1 measured while the liquid 200 is contained in the container 300.

In FIG. 7A, the real value at 920 MHz is approximately 10Ω, and the imaginary value at 920 MHz is approximately 177Ω. In FIG. 7B, the real value at 920 MHz is approximately 20 Ω, and the imaginary value at 920 MHz is approximately 196 Ω. According to FIGS. 7A and 7B, it can be seen that the impedance characteristics of the RFID tag 100-1 have less disturbance than the impedance characteristics of the comparative example 100A described above.

According to the RFID tag 100-1, the same effects as the RFID tag 100 can be obtained. Further, according to the RFID tag 100-1, for example, even if the vertical width of the meander-shaped first element 1 is not uniform due to manufacturing tolerances, the gap between the first element 1 and the second element 2 widens, so that the first Contact of the element 1 to the second element 2 can be suppressed. Therefore, it becomes unnecessary to manage manufacturing tolerances of the first element 1 and the like. Further, by widening the gap between the first element 1 and the second element 2, manufacturing of each wiring pattern is facilitated. As a result, the yield of the RFID tag 100-1 can be improved and manufacturing costs can be reduced.

FIG. 8 is a diagram showing a configuration example of an RFID tag 100-2 according to a second modification. The RFID tag 100-2 is different from the RFID tag 100 in that the first element 1 is omitted. The electrical length of each element is set as follows.

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 used. In this case, 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 .

Note that instead of the second element 2, the electrical length of the third element 3 may be set to be a multiple of λ/4 of the wavelength of the frequency used. In this case, the 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 .

Moreover, instead of the second element 2, the electrical length that is the sum of 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) is It may be set to a multiple of λ/4 of the wavelength of the frequency used. In this case, the electrical length of the second element 2 is set to a different electrical length from a multiple of λ/4 of the wavelength of the frequency used .

FIG. 9A is a diagram showing the impedance characteristics of the RFID tag 100-2 measured when the liquid 200 is not contained in the container 300. FIG. 9B is a diagram showing the impedance characteristics of the RFID tag 100-2 measured while the liquid 200 is contained in the container 300.

In FIG. 9A, the real value at 920 MHz is approximately 11Ω, and the imaginary value at 920 MHz is approximately 185Ω. In FIG. 9B, the real value at 920 MHz is approximately 16Ω, and the imaginary value at 920 MHz is approximately 196Ω. According to FIGS. 9A and 9B, it can be seen that the impedance characteristics of the RFID tag 100-2 have less disturbance than the impedance characteristics of the comparative example 100A described above.

According to the RFID tag 100-2, the same effects as the RFID tag 100 can be obtained by combining a plurality of elements having different electrical lengths and shapes.

Further, according to the RFID tag 100-2, for example, the first element 1 is not required, so that not only is it unnecessary to manage manufacturing tolerances of the first element 1, etc., but the structure is simplified. As a result, the yield of the RFID tag 100-2 is improved and manufacturing costs can be further reduced.

FIG. 10 is a diagram showing a configuration example of an RFID tag 100-3 according to a third modification. RFID tag 100-3 has fewer fourth elements 4 than RFID tag 100-2.

FIG. 11A is a diagram showing the impedance characteristics of the RFID tag 100-3 measured when the liquid 200 is not contained in the container 300. FIG. 11B is a diagram showing the impedance characteristics of the RFID tag 100-3 measured when the liquid 200 is contained in the container 300.

In FIG. 11A, the real value of 920 MHz is approximately 11Ω, and the imaginary value of 920 MHz is approximately 184Ω. In FIG. 11B, the real value at 920 MHz is approximately 17Ω, and the imaginary value at 920 MHz is approximately 196Ω. According to FIGS. 11A and 11B, it can be seen that the impedance characteristics of the RFID tag 100-3 have less disturbance than the impedance characteristics of the comparative example 100A described above. Further, according to FIGS. 11A and 11B, it can be seen that the impedance characteristics of the RFID tag 100-3 are not significantly disturbed compared to the impedance characteristics of the RFID tag 100-2 according to the second modification described above.

According to the RFID tag 100-3, the same effects as the RFID tag 100 can be obtained by combining a plurality of elements having different electrical lengths and shapes.

Further, according to the RFID tag 100-3, for example, since the number of fourth elements 4 can be reduced, not only is there no need to manage manufacturing tolerances, but the structure is also simplified. As a result, the yield of the RFID tag 100-3 is improved and manufacturing costs can be further reduced.

FIG. 12 is a diagram showing a configuration example of an RFID tag 100-4 according to a fourth modification. Compared to the RFID tag 100-3, the RFID tag 100-4 uses a fifth element 5 instead of the third element 3 and the fourth element 4. The second element 2 is the main part, and the fifth element 5 is the sub part.

The fifth element 5 is a conductor that is connected to the second element 2 so as to branch from the middle of the second element 2, which is a linear element, and extends parallel to the second element 2. The fifth element 5 is a branch element.

The connection point of the fifth element 5 to the second element 2 is, for example, a predetermined distance away from the connection point of the second element 2 and the loop-shaped conductor 20. It is preferable that the predetermined distance is set to a value between 5.0 mm and 100.0 mm, for example, since the resistance of the antenna will not become too high.

A gap is formed between the second element 2 and the portion where the fifth element 5 extends in the opposite direction to the loop-shaped conductor 20 side. This gap (separation distance in the Y-axis direction) is preferably set to a value of, for example, 1.0 mm to 30.0 mm because the resistance of the antenna will not become too high. Note that the fourth element 4 described above may be provided in this gap.

The electrical length of each element is set as follows.

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 used. 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 .

Further, instead of the second element 2, the electrical length of the fifth element 5 may be set to be a multiple of λ/4 of the wavelength of the frequency used. In this case, the electrical length of the second element 2 is set to a different electrical length from a multiple of λ/4 of the wavelength of the frequency used .

FIG. 13A is a diagram showing the impedance characteristics of the RFID tag 100-4 measured when the liquid 200 is not contained in the container 300. FIG. 13B is a diagram showing the impedance characteristics of the RFID tag 100-4 measured while the liquid 200 is contained in the container 300.

In FIG. 13A, the real value of 920 MHz is approximately 9Ω, and the imaginary value of 920 MHz is approximately 184Ω. In FIG. 13B, the real value at 920 MHz is approximately 16Ω, and the imaginary value at 920 MHz is approximately 193Ω. According to FIGS. 13A and 13B, it can be seen that the impedance characteristics of the RFID tag 100-4 have less disturbance than the impedance characteristics of the comparative example 100A described above. Further, according to FIGS. 13A and 13B, it can be seen that the impedance characteristics of the RFID tag 100-4 are approximately the same as the impedance characteristics of the RFID tag 100-3 according to the third modification described above, and are not significantly disturbed. .

According to the RFID tag 100-4, the same effects as the RFID tag 100 can be obtained by combining a plurality of elements having different electrical lengths and shapes.

Furthermore, according to the RFID tag 100-4, since the fourth element 4 can be omitted, not only is there no need to manage manufacturing tolerances, but the structure is also simplified. As a result, the yield of the RFID tag 100-4 is improved and manufacturing costs can be further reduced.

Further, according to the RFID tag 100-4, the branching point of the fifth element 5, that is, the position where the fifth element 5 is pulled out from the second element 2, is easily adjustable, so the design conditions of the RFID tag 100-4 are can have a degree of freedom. For example, in the case of a specially shaped container 300 in which the surface area of the RFID tag 100-4 must be made as small as possible, it is assumed that the area below the second element 2 (on the minus Y-axis direction side) is narrowed. Even in this case, it can also be applied to special containers 300 by placing the branch point of the fifth element 5 as close to the loop-shaped conductor 20 as possible and shortening the length of the portion of the fifth element 5 that extends in the Y-axis direction. It becomes possible. Therefore, as the number of containers 300 to which the RFID tag 100-4 can be applied increases, the production amount of the RFID tag 100-4 can be increased, and the manufacturing cost of the RFID tag 100-4 can be further reduced.

FIG. 14 is a diagram showing a configuration example of an RFID tag 100-5 according to a fifth modification. In the RFID tag 100-5, the fifth element 5 is omitted compared to the RFID tag 100-4. The RFID tag 100-5 has a simple structure including a second element 2 instead of a structure combining a plurality of elements having different electrical lengths and shapes.

The second element 2 of the RFID tag 100-5 is a linear conductor whose electrical length is set to be a multiple of approximately 1/4 of the wavelength of the frequency used.

The inventor of this application has confirmed that the impedance characteristics of the RFID tag 100-5 are equivalent to the impedance characteristics shown in FIGS. 13A and 13B, for example. The inventor of the present invention has also confirmed that the impedance characteristics of the RFID tag 100-5 have less disturbance than the impedance characteristics of the comparative example 100A described above.

Furthermore, the communication distance between the RFID tag 100-5 and the reader tends to be shorter than the communication distance between the RFID tags 100 to 100-4, but it is at least a practical communication distance (for example, about 1m to 7m). It has been confirmed that it is possible to secure Even if the communication distance is short, for example, by placing a reader on a belt conveyor that transports containers, identification information can be read, which can be used for inventory management of all kinds of products.

The reason for this excellent impedance characteristic is that by making the antenna element linear, the electrical coupling between the antenna element and the liquid is weakened compared to when only a meandering antenna element is used. it is conceivable that.

Conventionally, in order to ensure the electrical length necessary for wireless communication of the antenna section 30, a meander-shaped antenna element, a loop-shaped antenna element, etc. are often employed. However, when such an antenna element is used, the electrical coupling with the liquid becomes strong, and the impedance characteristics are greatly disturbed, making it impossible to ensure the desired antenna performance. Therefore, in the past, electrical coupling was reduced by increasing the distance from the antenna element to the liquid by providing a spacer between the antenna element and the container, and by inserting a metal sheet between the antenna element and the container. Measures were taken to reduce coupling.

According to the RFID tag 100-5 according to the fifth modification, such measures are not required, so that the manufacturing management of the RFID tag 100-5 is facilitated, and the time required for manufacturing the RFID tag 100-5 is reduced. Materials can be significantly reduced. Therefore, it is possible to significantly reduce the manufacturing cost of the RFID tag 100-5.

FIG. 15 is a diagram showing a configuration example of an RFID tag 100-6 according to a sixth modification. In the RFID tag 100-6, the fourth element 4 is omitted compared to the RFID tag 100-3 according to the third modification.

The inventor of the present invention has confirmed that the impedance characteristic of the RFID tag 100-6 has less disturbance than the impedance characteristic of the comparative example 100A described above. It was also confirmed that the communication distance between the RFID tag 100-6 and the reader was equivalent to the communication distance between the RFID tag 100-3 and the reader.

According to the RFID tag 100-6, for example, the fourth element 4 can be omitted, which not only eliminates the need to manage manufacturing tolerances but also simplifies the structure. As a result, the yield of the RFID tag 100-6 is improved and manufacturing costs can be further reduced.

FIG. 16 is a diagram showing a configuration example of an RFID tag 100-7 according to a seventh modification. The RFID tag 100-7 is different from the RFID tag 100 in that the third element 3 and fourth element 4 are omitted. When the first element 1 is the main part, the second element 2 is the sub part, and when the second element 2 is the main part, the first element 1 is the sub part.

The electrical length of each element is set as follows.

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 used. In this case, the 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 .

Note that instead of the first element 1, the electrical length of the second element 2 may be set to be a multiple of λ/4 of the wavelength of the frequency used. In this case, the electrical length of the first element 1 is set to be different from the electrical length that is a multiple of λ/4 of the wavelength of the frequency used .

The inventor of the present application has confirmed that the impedance characteristics of the RFID tag 100-7 have less disturbance than the impedance characteristics of the comparative example 100A described above. It was also confirmed that the communication distance between the RFID tag 100-7 and the reader was the same as the communication distance between the RFID tag 100 and the reader.

According to the RFID tag 100-7, for example, the third element 3 and the fourth element 4 can be omitted, which not only eliminates the need to manage manufacturing tolerances but also simplifies the structure. As a result, the yield of the RFID tag 100-7 is improved and manufacturing costs can be further reduced.

FIG. 17 is a diagram showing a configuration example of an RFID tag 100-8 according to an eighth modification. Compared to the RFID tag 100, the RFID tag 100-8 uses a fifth element 5 instead of the third element 3 and the fourth element 4. When the first element 1 is the main part, the second element 2 is the sub part, and when the second element 2 is the main part, the first element 1 is the sub part.

The electrical length of each element is set as follows.

For example, when 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 used, at least one of the length of the second element 2 and the length of the fifth element 5 is The electrical length is set to be different from the electrical length that is a multiple of λ/4 .

Further, when 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 used, at least one of the length of the first element 1 and the length of the fifth element 5 is The electrical length is set to be different from the electrical length that is a multiple of λ/4 .

Further, when the electrical length of the fifth element 5 is set to a multiple of λ/4 of the wavelength of the frequency used, at least one of the electrical length of the first element 1 and the length of the second element 2 is set to λ/4. The electrical length is set to be different from the electrical length that is a multiple of 4 .

The inventor of the present application has confirmed that the impedance characteristics of the RFID tag 100-8 have less disturbance than the impedance characteristics of the comparative example 100A described above. It was also confirmed that the communication distance between the RFID tag 100-8 and the reader is equivalent to the communication distance between the RFID tag 100 and the reader.

According to the RFID tag 100-8, since the fourth element 4 can be omitted, for example, not only is there no need to manage manufacturing tolerances, but the structure is also simplified. As a result, the yield of the RFID tag 100-8 is improved and manufacturing costs can be further reduced.

Note that each of the RFID tags 100 to 100-8 according to the present embodiment is applicable not only to UHF band radio waves but also to VHF band, SHF band, and other radio waves. If the frequency used by the RFID tags 100 to 100-8 is in the UHF band, for example 860 to 960 MHz, 915 to 925 MHz, etc., the UHF band has a higher frequency than the VHF band, so the wavelength is shorter and the antenna It is advantageous for downsizing. Therefore, by making the RFID tags 100 to 100-8 according to the present embodiment into a shape suitable for radio waves in the UHF band, it is possible to reduce the size of the IC chip 10, and also to make the RFID tags with small memory capacity and inexpensive. can be obtained.

Further, each of the RFID tags 100 to 100-8 according to the present embodiment can be applied to either an electromagnetic induction type wireless tag or a radio wave type wireless tag. In particular, when each of the RFID tags 100 to 100-8 is applied to a radio wave type wireless tag, a predetermined wireless communication distance with the reader can be secured. The predetermined wireless communication distance is, for example, in the range from 0 m to 20 m.

Note that the RFID tags 100 to 100-8 according to the present embodiment can be used in the UHF band, VHF band, or SHF band, regardless of whether the RFID tags 100 to 100-8 exist in the air (in the atmosphere) or in the water. Wireless communication is possible using radio waves such as radio waves. For example, a container 300 having RFID tags 100 to 100-8 is stored in a bucket or the like, and the RFID tags 100 to 100-8 are used whether the bucket contains water or not. wireless communication with the reader is possible. In the following, wireless communication is possible using the RFID tag 100-9 according to the ninth modification example, which has technical features common to the RFID tags 100 to 100-8, even when installed in the air or underwater. Explain that.

FIG. 18A is a first diagram showing the frequency characteristics of an RFID tag installed in the air. FIG. 18B is a second diagram showing the frequency characteristics of an RFID tag installed in the air. FIG. 18C is a third diagram showing the frequency characteristics of an RFID tag installed in the air. FIG. 18D is a fourth diagram showing the frequency characteristics of an RFID tag installed in the air. FIG. 18E is a fifth diagram showing the frequency characteristics of an RFID tag installed in the air.

18A to 18E show the frequency characteristics of the RFID tag 100-9 installed in the air. In each figure, the horizontal axis represents the frequency of radio waves for wireless communication, and the vertical axis represents the communicable distance from the RFID tag 100-9 to the reader. Note that the details of the configuration of the RFID tag 100-9 will be described later.

FIG. 18A shows data of an RFID tag 100-9 attached to a 500 ml PET bottle containing liquid (not frozen). From FIG. 18A, it can be seen that in the case of a 500 ml PET bottle, a wide range of 830 MHz to 1040 MHz can be secured as the resonant frequency band when the communication distance is set to 10 cm or more.

FIG. 18B shows data for an RFID tag 100-9 attached to a 900 ml glass bottle containing alcohol (eg, 25% ethanol added to water). From FIG. 18B, it can be seen that in the case of a 900 ml glass bottle, a resonant frequency band of, for example, 760 MHz to 1200 MHz can be secured when the communication distance is set to 10 cm or more.

FIG. 18C shows data from an RFID tag 100-9 attached to a 1000 ml paper pack containing water. From FIG. 18C, it can be seen that in the case of a 1000 ml paper pack, for example, a resonance frequency band of 780 MHz to 1200 MHz can be secured when the communication distance is set to 10 cm or more.

FIG. 18D shows the data of the RFID tag 100-9 attached to a 1500 ml plastic bottle containing oil (salad oil manufactured by Nisshin Oilio). From FIG. 18D, it can be seen that in the case of a 1500 ml PET bottle, for example, a resonance frequency band of 700 MHz to 1200 MHz can be secured when the communication distance is set to 10 cm or more.

FIG. 18E shows data of the RFID tag 100-9 attached to a 500 ml plastic bottle (frozen) containing liquid. From FIG. 18E, it can be seen that in the case of a frozen PET bottle, for example, a resonance frequency band of 700 MHz to 1200 MHz can be secured when the communication distance is set to 10 cm or more.

Next, with reference to FIGS. 19A to 20D, a 500 ml plastic bottle equipped with an RFID tag 100-9 is placed in a bucket, and the frequency characteristics before and after filling the bucket with water will be described.

FIG. 19A is a first diagram for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water. FIG. 19B is a second diagram for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water. FIG. 19C is a third diagram for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water. FIG. 19D is a fourth diagram for explaining the frequency characteristics of an RFID tag that can be installed both in the air and in water.

As shown in FIGS. 19A to 19D, for example, a 500 ml plastic bottle (container 300) is housed in a bucket (container 400) that can accommodate water 311. 19A shows a state in which water 311 is not contained in the container 400, and FIGS. 19B to 19C show states in which water 311 is contained in the container 400.

It is assumed that the amount of water 311 is larger in the order of FIG. 19B, FIG. 19C, and FIG. 19D. The state shown in FIG. 19B is just before the RFID tag 100-9 is immersed in water, that is, most of the container 300 is immersed in water 311, but the RFID tag 100-9 is not immersed in water 311. The state shown in FIG. 19C is a state immediately after the RFID tag 100-9 is immersed in water, that is, a state where a small amount of water 311 is present on the top surface of the RFID tag 100-9. The state where a small amount of water 311 is present 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. In the state of FIG. 19D, the amount of water 311 has increased compared to the state of FIG. 19C, and for example, the distance from the RFID tag 100-9 to the water surface 311a is about 15 cm.

The frequency characteristics of the RFID tag 100-9 verified under these conditions are shown in FIGS. 20A to 20D. 20A is a diagram showing the frequency characteristics of the RFID tag shown in FIG. 19A, FIG. 20B is a diagram showing the frequency characteristics of the RFID tag shown in FIG. 19B, FIG. 20C is a diagram showing the frequency characteristics of the RFID tag shown in FIG. 19C, and FIG. 20D FIG. 19D is a diagram showing the frequency characteristics of the RFID tag shown in FIG. 19D. In each figure, the horizontal axis represents the frequency of radio waves for wireless communication, and the vertical axis represents the communicable distance from the RFID tag 100-9 to the reader. Note that these data were measured when the distance L from the reader antenna 500 to the RFID tag 100-9 was 25 cm, as shown in FIG. 19A.

The frequency characteristics in FIG. 20A correspond to the state in FIG. 19A. From FIG. 20A, it can be seen that when the container 400 does not contain water 311, a wide range of 800 MHz to 1200 MHz can be secured as the resonance frequency band when the communication distance is set to 10 cm or more.

The frequency characteristics in FIG. 20B correspond to the state in FIG. 19B. From FIG. 20B, it can be seen that when the RFID tag 100-9 is not immersed in water 311, a wide range of 800 MHz to 1200 MHz can be secured as the resonant frequency band when the communication distance is set to 10 cm or more.

The frequency characteristics in FIG. 20C correspond to the state in FIG. 19C. From FIG. 20C, when the RFID tag 100-9 is slightly immersed in water 311, the overall communication distance is shorter than the data in FIG. 20B, but communication is possible except around 840 MHz and around 1100 MHz. It can be seen that a wide distance can be secured.

The frequency characteristics in FIG. 20D correspond to the state in FIG. 19D. From FIG. 20D, it can be seen that even if the distance from the RFID tag 100-9 to the water surface 311a becomes long, a wide communicable distance can be secured.

Although data is not illustrated in this embodiment, even if the distance of the RFID tag 100-9 to the water surface 311a is longer than 15 cm, for example, if the distance is up to about 30 cm, the RFID tag 100-9 It has been demonstrated that wireless communication using .

FIG. 21 is a diagram showing a configuration example of an RFID tag 100-9 according to a ninth modification. The difference from the RFID tag 100-2 shown in FIG. 8 is that the RFID tag 100-9 has an increased number of fourth elements 4.

According to the RFID tag 100-9, electrical coupling between the antenna element and the liquid can be relaxed. Furthermore, according to the RFID tag 100-9, by combining a plurality of elements with different electrical lengths, deviations in resonance conditions are corrected, and a matching circuit that is robust against the wavelength shortening effect of the liquid can be obtained. Further, according to the RFID tag 100-9, by combining a plurality of elements with different electrical lengths, the reception strength of radio waves at the antenna section 30 can be increased. In particular, by increasing the number of fourth elements 4, the reception strength of radio waves at the antenna section 30 can be further increased even in underwater applications. Furthermore, according to the RFID tag 100-9, although it is basically used in the air, it can also be used when the PET bottle is immersed in a container filled with ice water or the like in order to cool it when opening a store. Inventory management becomes possible. Therefore, it is possible to save time and effort such as taking out a plastic bottle from a container containing ice water or the like and checking the number of items in stock. Furthermore, even if plastic bottles or the like are submerged in water due to an earthquake, flood, etc., the number of bottles in stock can be checked while they are submerged in water.

The configurations shown in the embodiments described above are examples of the contents of the present invention, and can be combined with other known techniques, and the configurations can be modified without departing from the gist of the present invention. It is also possible to omit or change parts.

1: First element 2: Second element 3: Third element 4: Fourth element 5: Fifth element 10: IC chip 20: Loop-shaped conductor 30: Antenna section 30A: Conductor section 30B: Conductor section 31: Element 40 : Sheet 100 : RFID tag 100-1 : RFID tag 100-2 : RFID tag 100-3 : RFID tag 100-4 : RFID tag 100-5 : RFID tag 100-6 : RFID tag 100-7 : RFID tag 100- 8: RFID tag 100-9: RFID tag 200: Liquid 300: Container 301: Cap 302: Label

Claims (5)

An IC chip on which identification information is recorded,
a loop-shaped conductor connected to the IC chip;
a pair of meander elements , which are meander-shaped conductors connected to the loop-shaped conductor and extending in a predetermined direction away from the loop-shaped conductor ; an antenna section having a lattice-shaped conductor;
Equipped with
Each of the pair of lattice-shaped conductors is
a linear element that is a linear conductor that is connected to the meander element so as to branch from the middle of the meander element and extends in the predetermined direction;
a hook element, which is a hook-shaped conductor provided at the tip of the linear element, bent in a direction opposite to the direction in which the linear element extends from the tip of the linear element, and extending toward the loop-shaped conductor;
a lattice element that is a linear conductor extending from the linear element toward the hook element, and connecting the linear element and the hook element;
has
(i) The meander element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency, and at least one of the linear element and the hook element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency. The electrical length is set to be different from the electrical length,
(ii) The linear element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency, and at least one of the meander element and the hook element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency. The electrical length is set to be different from the electrical length,
(iii) The total of the straight line element and the hook element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency, and the meander element is set to have an electrical length that is a multiple of 1/4 of the wavelength of the used frequency. is set to have an electrical length different from the electrical length, or
(iv) The total electrical length of the linear element, the hook element, and the grating element is set to be a multiple of 1/4 of the wavelength of the used frequency, and the meander element is set to be 1/4 of the wavelength of the used frequency. The electrical length is set to be different from the electrical length that is a multiple of 4,
RFID tag. The RFID tag according to claim 1 , wherein the frequency used is a frequency in the UHF band (860 to 960 MHz). Provided on the surface of a container containing liquid,
3. The RFID tag according to claim 1 , wherein the liquid is any one of water, oil, and alcohol, or a mixture thereof . A plastic bottle affixed with the RFID tag according to any one of claims 1 to 3 . An antenna used as the antenna section of the RFID tag according to any one of claims 1 to 3 .

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