JP2020014074A - RFID tag - Google Patents

Abstract

To provide an RFID tag that includes an antenna and an IC chip and performs wireless communication enabling (1) elimination of a risk of burnout due to microwave heating or microwave drying and (2) elimination of a possibility of interference with wireless communication for different applications.SOLUTION: An RFID tag R for performing wireless communication includes an antenna 11 and an IC chip 12. The antenna 11 is a linear antenna bent in a meander shape. A resonance condition of the antenna 11 is satisfied at a frequency for wireless communication of the RFID tag R. A gain of the antenna 11 is substantially minimized at a frequency of an undesired wave of the RFID tag R. Specifically, a feeding point 13 of the antenna 11 is provided at a position offset from a center point 14 of the antenna 11.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a technology for preventing an RFID tag having an antenna and an IC chip for wireless communication from being (1) burned out by microwave heating or microwave drying, and (2) not to interfere with wireless communication for different applications. About.

  A bar code is attached to the food container to store various information about the food. Examples of various information related to food include food management information (such as a method of storing food), food price information, and food heating information (such as a method of performing microwave heating).

  Recently, various kinds of information about foods have become enormous. Then, even if the barcode is attached to the food container, various information on the food cannot be stored in the barcode. Therefore, by attaching the RFID tag to the food container, various information on the food can be sufficiently stored in the RFID tag (for example, see Non-Patent Document 1 and the like).

"The Declaration of 100 Billion Convenience Electronic Tags Declaration-To Solve Social Issues in the Supply Chain-", [online], April 18, 2017, Commerce and Information Policy Bureau, METI, [Search on July 5, 2018], Internet <URL: http://www.meti.go.jp/press/2017/04/20170418005/20170418005.html>

  By the way, in an RFID tag, a conductive material (for example, a metal material, a carbon material, a conductive polymer material, or the like) is included in an antenna or the like, and a semiconductor is included in an IC chip. Then, when the food is heated in a microwave oven, the RFID tag may be burned. Then, the food container may be melted by the heat generated by burning, and the conductive substance and the semiconductor may be scattered in the microwave oven. Of course, if the RFID tag is removed from the food container before the food is placed in the microwave, there is no risk of the RFID tag burning. However, it takes time to remove the RFID tag from the food container, and there is a possibility that the RFID tag may be forgotten to be removed from the food container.

  Then, the RFID tag may interfere with wireless communication for different uses. Of course, if a frequency filter that removes frequencies for wireless communication for different applications is installed, there is no risk that the RFID tag will interfere with wireless communication for different applications. However, it takes time to design the frequency filter, and a place for installing the frequency filter is required.

  Therefore, in order to solve the above-described problems, the present disclosure is intended to eliminate the possibility that an RFID tag that includes an antenna and an IC chip and performs wireless communication can be burned out by (1) microwave heating or microwave drying, and (2) different applications. To eliminate the risk of interference with other wireless communications.

  In order to solve the above-mentioned problem, by optimizing the size of the linear antenna bent in a meandering shape in the dipole length direction and the direction perpendicular thereto, the gain is almost minimized at the frequency of the undesired wave of the RFID tag. To reduce the current flowing through the IC chip.

  Specifically, the present disclosure is an RFID tag that includes an antenna and an IC chip and performs wireless communication, wherein the antenna is a linear antenna bent in a meander shape, and the resonance condition of the antenna is the following. An RFID tag characterized by being satisfied with a frequency for wireless communication of the RFID tag, wherein the gain of the antenna is substantially minimized at the frequency of the undesired wave of the RFID tag.

  According to this configuration, the RFID tag that includes an antenna and an IC chip and performs wireless communication does not suffer from (1) the risk of being burned out by an undesired wave (such as a microwave for heating or drying) of the RFID tag, and (2) It is possible to eliminate the possibility of interfering with wireless communications for different applications.

  Further, the present disclosure is the RFID tag, wherein a feed point of the antenna is installed at a position offset from a center point of the antenna.

  Since the frequency of the high voltage impulse such as static electricity is DC compared to the frequency of wireless communication of the RFID tag, according to this configuration, the feeding point of the antenna can be short-circuited in a DC manner. Can be protected from high voltage impulses such as static electricity.

  Further, the present disclosure is the RFID tag, wherein the frequency of the undesired wave of the RFID tag is a frequency for microwave heating or microwave drying.

  According to this configuration, it is possible to eliminate the risk that the RFID tag that includes the antenna and the IC chip and performs wireless communication will be damaged by microwave heating or microwave drying.

  Further, the present disclosure is the RFID tag, wherein the frequency of the undesired wave of the RFID tag is a frequency for wireless communication different from the frequency for wireless communication of the RFID tag.

  According to this configuration, it is possible to eliminate the possibility that the RFID tag having the antenna and the IC chip and performing the wireless communication may interfere with the wireless communication for different applications.

  As described above, according to the present disclosure, the RFID tag that includes an antenna and an IC chip and performs wireless communication does not (1) burn out due to microwave heating or microwave drying, and (2) interferes with wireless communication for different applications. You can eliminate fear.

1 is a diagram illustrating a configuration of a microwave heating container according to the present disclosure. 1 is a diagram illustrating a configuration of an antenna according to a first embodiment of the present disclosure. FIG. 3 is a diagram illustrating performance of the antenna according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating a method for designing an antenna according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating an induced current of the antenna according to the first embodiment of the present disclosure. It is a figure showing the composition of the antenna of a 2nd embodiment of this indication. FIG. 11 is a diagram illustrating performance of the antenna according to the second embodiment of the present disclosure. It is a figure showing the composition of the antenna of a 3rd embodiment of this indication. It is a figure showing the performance of the antenna of a 3rd embodiment of this indication. 1 is a diagram illustrating a configuration of an RFID tag sticking container according to the present disclosure.

  Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of the present disclosure, and the present disclosure is not limited to the following embodiments.

  FIG. 1 shows the configuration of a microwave heating container according to the present disclosure. The microwave oven container C is composed of a container 2 that stores an RFID tag R and contents 3. The RFID tag R includes an antenna pattern 1 and an antenna substrate 1 '(a dielectric substrate, a dielectric film, and the like).

  The antenna pattern 1 of the RFID tag R includes an antenna 11 and an IC chip 12, which will be described later with reference to FIGS. Here, the antenna pattern 1 of the RFID tag R is printed on a member that does not absorb microwaves (the antenna substrate 1 'in FIG. 1). Therefore, the antenna pattern 1 of the RFID tag R can be easily manufactured. Then, the RFID tag R with the antenna substrate 1 ′ is attached to the surface of the container 2.

  FIG. 2 illustrates a configuration of the antenna according to the first embodiment of the present disclosure. In the first embodiment, the antenna pattern 1 is arranged in free space in order to verify the principle of the present disclosure.

  The antenna 11 is a linear antenna bent in a meandering shape. The surface on which the antenna pattern 1 is formed is an xy plane, and the direction perpendicular to the xy plane is the z axis. The direction of the dipole length of the antenna 11 is set to the y-axis, and the direction orthogonal thereto is set to the x-axis. It is assumed that the origin of the xyz three-dimensional space is at the center point in the two-dimensional plane occupied by the antenna 11.

  The size of the antenna 11 in the dipole length direction is designed to be 2L = 18.2 mm × 2. The size of the antenna 11 in the direction orthogonal thereto is designed to be W = 15.4 mm. The offset between the feeding point 13 and the center point 14 of the antenna 11 is designed to be C = 3.5 mm along the above-described orthogonal direction of the antenna 11. The strip width of the antenna 11 is designed to be L / 36 mm. The strip gap of the antenna 11 is designed to be L / 24 mm. The IC chip 12 is connected not to the center point 14 of the antenna 11 but to the offset feed point 13.

  FIG. 3 shows the performance of the antenna according to the first embodiment of the present disclosure. At a frequency of 920 MHz for wireless communication of the RFID tag R, the reflection coefficient of the antenna 11 is minimized, and the effective gain of the antenna 11 is maximized. That is, the resonance condition of the antenna 11 is satisfied at the wireless communication frequency of 920 MHz of the RFID tag R. On the other hand, at a frequency of 2.45 GHz for heating the microwave oven, the effective gain and the directivity gain of the antenna 11 are minimal.

  FIG. 4 shows a method for designing an antenna according to the first embodiment of the present disclosure. The strip of the antenna 11 in the dipole length direction forms an inductor, and the strip of the antenna 11 in the direction orthogonal thereto forms a line capacitor. At a frequency of 920 MHz for wireless communication of the RFID tag R, the resonance condition between the inductor and the line capacitor is satisfied. Note that FIG. 4 differs from FIG. 2 in the number of meandering bendings.

  Here, at a frequency of 920 MHz for wireless communication of the RFID tag R, the resonance condition of the antenna 11 is satisfied with various L and W. However, at a microwave heating frequency of 2.45 GHz, the minimum gain of the antenna 11 is realized at specific L and W. For example, when L is appropriately designed when W is set to 9 mm, the resonance condition of the antenna 11 is satisfied at the frequency of 920 MHz for wireless communication of the RFID tag R, and the frequency for heating the microwave oven is 2. At 45 GHz, the minimum gain of the antenna 11 is realized. Note that, in a linear antenna bent in a meandering shape, unlike a linear antenna that is not bent in a meandering shape, the frequency at which the gain minimum of the linear antenna is realized is lower than the frequency 920 MHz for wireless communication of the RFID tag R. Therefore, it does not necessarily have to be about twice.

  On the other hand, when L is properly designed when W is set to 8 mm, the resonance condition of the antenna 11 is satisfied at the frequency of 920 MHz for wireless communication of the RFID tag R, but the minimum gain of the antenna 11 is realized. This is done at a frequency of 2.6 GHz, which is higher than the microwave heating frequency of 2.45 GHz. At this time, by designing W to be longer, it is possible to lower the frequency at which the minimum gain of the antenna 11 is realized.

  When L is properly designed when W is set to 10 mm, the resonance condition of the antenna 11 is satisfied at the frequency of 920 MHz for wireless communication of the RFID tag R, but the minimum gain of the antenna 11 is realized. At a frequency of 2.3 GHz, which is lower than the frequency for microwave heating of 2.45 GHz. At this time, by designing W to be shorter, the frequency at which the gain of the antenna 11 is minimized can be made higher.

  Even when the frequency for heating the microwave oven has a width or a bimodal property, the gain of the antenna 11 may be substantially minimized at the frequency for heating the microwave oven.

  FIG. 5 shows an induced current of the antenna according to the first embodiment of the present disclosure. The irradiation wave source is a minute dipole, the direction of the minute dipole is the y direction, the position of the minute dipole is 300 mm on the z-axis, and the applied power is maintained at 500 W during the frequency sweeping process.

  At a frequency of 920 MHz for wireless communication of the RFID tag R, the induced current of the terminating resistor 50Ω at the feeding point 13 of the antenna 11 reaches a maximum (574 mA). On the other hand, at a microwave heating frequency of 2.45 GHz, the induced current and induced power of the termination resistance 50Ω at the feed point 13 of the antenna 11 are extremely small (0.247 mA and 3 μW), and the induced current on the strip of the antenna 11 is It becomes minimum at the center point 14 of the antenna 11 (the y-axis position is 0 mm).

  In other words, by optimizing the size 2L and W of the linear antenna 11 bent in a meandering shape in the dipole length direction and the orthogonal direction to the dipole length, the gain is almost minimized at the microwave heating frequency of 2.45 GHz. The current flowing through the IC chip 12 is reduced. Then, it is possible to eliminate the risk that the RFID tag R having the antenna 11 and the IC chip 12 and performing wireless communication will be burned out by heating in the microwave oven.

  Furthermore, since there is no possibility that the RFID tag R will be burned out by heating in the microwave oven, the disposal method of the container 2 can be read from the RFID tag R when the container 2 is disposed, and the content is read from the RFID tag R when the content 3 is reheated. The cooking method of the object 3 can be read.

  Then, as shown in FIG. 2, the offset between the feeding point 13 and the center point 14 of the antenna 11 is designed to have a finite value C = 3.5 mm. Then, since the frequency of the high-voltage impulse such as static electricity is DC compared to the frequency 920 MHz for wireless communication of the RFID tag R, the feed point 13 of the antenna 11 can be short-circuited DC. 12 can be protected from high voltage impulses such as static electricity.

  Here, in order to short-circuit the feed point 13 of the antenna 11 in a DC manner, it is desirable to increase the offset C between the feed point 13 of the antenna 11 and the center point 14 (see FIG. 2). On the other hand, at a microwave heating frequency of 2.45 GHz, it is desirable to reduce the offset C between the feeding point 13 and the center point 14 of the antenna 11 in order to reduce the current flowing through the IC chip 12 ( (See the lower part of FIG. 5). Therefore, it is desirable to design the offset C between the feeding point 13 and the center point 14 of the antenna 11 so as to optimize the trade-off between the two. It is necessary to design the offset C between the feeding point 13 and the center point 14 of the antenna 11 so that the imaginary part of the impedance of the antenna 11 becomes zero.

  FIG. 6 illustrates a configuration of the antenna according to the second embodiment of the present disclosure. In the second embodiment, the antenna pattern 1 is disposed on a dielectric substrate for verification in an anechoic chamber. Regarding the dielectric substrate, the thickness is 0.5 mm, the relative permittivity is 3.5, and the dielectric loss tangent is 0.006. It is assumed that the material of the strip of the antenna 11 is copper and the thickness thereof is zero.

  The antenna 11 is a linear antenna bent in a meandering shape. The surface on which the antenna pattern 1 is formed is an xy plane, and the direction perpendicular to the xy plane is the z axis. The direction of the dipole length of the antenna 11 is set to the y-axis, and the direction orthogonal thereto is set to the x-axis. It is assumed that the origin of the xyz three-dimensional space is at the center point in the two-dimensional plane occupied by the antenna 11.

  The size of the antenna 11 in the dipole length direction is designed to be 2L = 24 mm × 2. The size of the antenna 11 in the direction orthogonal thereto is designed to be W = 11 mm. The offset between the feeding point 13 and the center point 14 of the antenna 11 along the above-described orthogonal direction of the antenna 11 is designed to be C = 6 mm. The strip width of the antenna 11 is designed to be L / 48 mm. The strip gap of the antenna 11 is designed to be L / 36 mm. The IC chip 12 is connected not to the center point 14 of the antenna 11 but to the offset feed point 13.

  FIG. 7 shows the performance of the antenna according to the second embodiment of the present disclosure. At a frequency of 920 MHz for wireless communication of the RFID tag R, the reflection coefficient of the antenna 11 is minimized, and the effective gain of the antenna 11 is maximized. That is, the resonance condition of the antenna 11 is satisfied at the wireless communication frequency of 920 MHz of the RFID tag R. On the other hand, at a microwave heating frequency of 2.45 GHz, the effective gain of the antenna 11 becomes minimal.

  The induced current of the antenna according to the second embodiment of the present disclosure will be calculated. The irradiation wave source is a small dipole. In the first case, the direction of the minute dipole is the y direction, and the position of the minute dipole is 300 mm on the x-axis. In the second case, the direction of the small dipole is in the z-direction, and the position of the small dipole is 300 mm on the y-axis. In the third case, the direction of the minute dipole is the y direction, and the position of the minute dipole is 300 mm on the z-axis. In each case, the applied frequency is 2.45 GHz and the applied power is 500 W.

  In the first case, the induced current and the induced power of the termination resistance 50Ω at the feeding point 13 of the antenna 11 are extremely small (4.87 mA and 1.19 mW). In the second case, the induced current and induced power of the termination resistor 50Ω at the feed point 13 of the antenna 11 are extremely small (0.39 mA and 0.01 mW). In the third case, the induced current and induced power of the terminating resistor 50Ω at the feed point 13 of the antenna 11 are extremely small (1.75 mA and 0.15 mW). In either case, the induced current on the strip of antenna 11 is minimal at center point 14 of antenna 11. As described above, due to the influence of the dielectric substrate, the offset C = 6 mm between the feeding point 13 and the center point 14 of the antenna 11 is increased, and the induced power of the terminating resistor 50Ω is slightly increased.

  FIG. 8 illustrates a configuration of the antenna according to the third embodiment of the present disclosure. In the third embodiment, assuming an actual RFID tag R, the antenna pattern 1 is sandwiched between dielectric films. As for the dielectric film, a 2.5-dimensional model is adopted assuming that the thickness is 50 μm, the relative dielectric constant is 3.0, the dielectric loss tangent is 0.006, and the dielectric film continues infinitely on the XY plane. It is assumed that the material of the strip of the antenna 11 is copper and the thickness thereof is zero.

  The antenna 11 is a linear antenna bent in a meandering shape. The surface on which the antenna pattern 1 is formed is an xy plane, and the direction perpendicular to the xy plane is the z axis. The direction of the dipole length of the antenna 11 is set to the y-axis, and the direction orthogonal thereto is set to the x-axis. It is assumed that the origin of the xyz three-dimensional space is at the center point in the two-dimensional plane occupied by the antenna 11.

  The size of the antenna 11 in the dipole length direction is designed to be 2L = 18.5 mm × 2. The size of the antenna 11 in the direction orthogonal thereto is designed to be W = 13 mm. The offset between the feed point 13 and the center point 14 of the antenna 11 along the above-described orthogonal direction of the antenna 11 is designed to be C = 3 mm. The strip width of the antenna 11 is designed to be L / 48 mm. The strip gap of the antenna 11 is designed to be L / 36 mm. The IC chip 12 is connected not to the center point 14 of the antenna 11 but to the offset feed point 13.

  FIG. 9 shows the performance of the antenna according to the third embodiment of the present disclosure. At a frequency of 920 MHz for wireless communication of the RFID tag R, the reflection coefficient of the antenna 11 is minimized, and the effective gain of the antenna 11 is maximized. That is, the resonance condition of the antenna 11 is satisfied at the wireless communication frequency of 920 MHz of the RFID tag R. On the other hand, at a microwave heating frequency of 2.45 GHz, the effective gain of the antenna 11 is minimal.

  The induced current of the antenna according to the third embodiment of the present disclosure will be calculated. The irradiation wave source is a small dipole. In the first case, the direction of the minute dipole is the y direction, and the position of the minute dipole is 300 mm on the x-axis (however, since the dielectric film continues infinitely on the XY plane, it floats 10 mm in the z-axis direction). is there. In the second case, the direction of the minute dipole is the z-direction, and the position of the minute dipole is 300 mm on the y-axis (however, since the dielectric film continues infinitely on the XY plane, it floats 10 mm in the z-axis direction). is there. In the third case, the direction of the minute dipole is the y direction, and the position of the minute dipole is 300 mm on the z-axis. In each case, the applied frequency is 2.45 GHz and the applied power is 500 W.

  In the first case, the induced current and the induced power of the termination resistance 50Ω at the feeding point 13 of the antenna 11 are extremely small (2.55 mA and 0.33 mW). In the second case, the induced current and the induced power of the termination resistor 50Ω at the feed point 13 of the antenna 11 are extremely small (0.35 mA and 0.01 mW). In the third case, the induced current and the induced power of the termination resistance 50Ω at the feed point 13 of the antenna 11 are extremely small (0.60 mA and 0.02 mW). In either case, the induced current on the strip of antenna 11 is minimal at center point 14 of antenna 11. Thus, due to the influence of the dielectric film, the offset C = 3 mm between the feeding point 13 and the center point 14 of the antenna 11 is reduced, and the induced power of the termination resistance 50Ω is reduced by one digit.

  FIG. 10 shows a configuration of the RFID tag sticking container of the present disclosure. The RFID tag sticking container C 'includes an RFID tag R and a container 4 for storing contents. The RFID tag R includes an antenna pattern 1 and an antenna substrate 1 '(a dielectric substrate, a dielectric film, and the like).

  The antenna pattern 1 of the RFID tag R includes the antenna 11 and the IC chip 12 described above with reference to FIGS. Here, the antenna pattern 1 of the RFID tag R is printed on a member that does not absorb microwaves (the antenna substrate 1 'in FIG. 10). Therefore, the antenna pattern 1 of the RFID tag R can be easily manufactured. Then, the RFID tag R with the antenna substrate 1 ′ is attached to the surface of the container 4.

  By optimizing the size 2L and W in the dipole length direction and the orthogonal direction to the dipole length of the linear antenna 11 bent in a meander shape, the gain can be increased at a frequency of 2.45 GHz for wireless communication for different applications. The current is substantially minimized, and the current flowing through the IC chip 12 is reduced. Then, it is possible to eliminate the possibility that the RFID tag R that includes the antenna 11 and the IC chip 12 and performs wireless communication may interfere with wireless communication for different applications.

  Further, as shown in FIGS. 2, 6, and 8, the offset between the feeding point 13 and the center point 14 of the antenna 11 is designed to have a finite value C. Then, since the frequency of the high-voltage impulse such as static electricity is DC compared to the frequency 920 MHz for wireless communication of the RFID tag R, the feed point 13 of the antenna 11 can be short-circuited DC. 12 can be protected from high voltage impulses such as static electricity.

  In FIGS. 1 to 9, the risk that the RFID tag R operated by an electromagnetic wave having a frequency of 920 MHz for wireless communication is damaged by an electromagnetic wave having a frequency of 2.45 GHz for heating a microwave oven is eliminated. Generalizing FIGS. 1 to 9, there is a possibility that an RFID tag R operated by an electromagnetic wave having an arbitrary frequency for wireless communication may be burned by an electromagnetic wave having an arbitrary frequency for microwave heating or microwave drying. You may not need it.

  In FIG. 10, the RFID tag R operated by an electromagnetic wave having a frequency of 920 MHz for wireless communication is prevented from being interfered by an electromagnetic wave having a frequency of 2.45 GHz for wireless communication for a different purpose. By generalizing FIG. 10, an RFID tag R that operates by an electromagnetic wave having an arbitrary frequency for wireless communication has an arbitrary frequency for wireless communication for a different application (≠ a frequency for wireless communication of the RFID tag R). May eliminate the risk of interference.

  According to the RFID tag of the present disclosure, the RFID tag that includes an antenna and an IC chip and performs wireless communication does not (1) eliminate the risk of burning due to microwave heating or microwave drying, and (2) may interfere with wireless communication for different applications. Can be eliminated.

C: microwave oven container C ': RFID tag-attached container R: RFID tag 1: antenna pattern 1': antenna substrate 2: container 3: contents 4: container 11: antenna 12: IC chip 13: feed point 14: Center point

Claims (4)

An RFID tag that includes an antenna and an IC chip and performs wireless communication,
The antenna is a linear antenna bent in a meandering shape,
The resonance condition of the antenna is satisfied at a frequency for wireless communication of the RFID tag,
The gain of the antenna is substantially minimized at a frequency of an undesired wave of the RFID tag.   The RFID tag according to claim 1, wherein the feeding point of the antenna is installed at a position offset from a center point of the antenna.   3. The RFID tag according to claim 1, wherein the frequency of the undesired wave of the RFID tag is a frequency for microwave heating or microwave drying.   The RFID tag according to claim 1, wherein a frequency of the undesired wave of the RFID tag is a frequency for wireless communication different from a frequency for wireless communication of the RFID tag.

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