JP2019168260A - Non-contact communication medium - Google Patents

Abstract

An object of the present invention is to accurately detect non-contact environmental changes such as moisture without increasing the size. An antenna (12a, 12b) through which a current flows by non-contact power supply, an IC chip (11) that performs non-contact communication via the antennas (12a, 12b) by supplying a current flowing to the antennas (12a, 12b), and a dielectric , A sensor electrode 21a, 21b which is attached to the sensor unit 20 with a predetermined interval therebetween, and a resistance value of the sensor unit 20 calculated by a current flowing between the electrodes 21a, 21b. A sensor circuit 22 for detecting the sensor value, converting the sensor value into a digital value, and outputting the digital value to the IC chip 11; the antennas 12a, 12b and the electrodes 21a, 21b are connected to the currents flowing through the antennas 12a, 12b. And the direction of the current flowing between the electrodes 21a and 21b are arranged so as to form a relative angle that is not parallel. [Selection diagram] Fig. 1

Description

  The present invention relates to a technique for detecting a change in environment without contact.

  Conventionally, a mechanism for detecting moisture contained in building materials such as soil, food, and wood using a porous ceramic has been put into practical use. Since the porous ceramic has a characteristic that the impedance changes depending on the moisture content inside, the moisture content of the object to be measured can be detected by detecting the change in impedance.

  As one of such mechanisms, a rod-shaped antenna is embedded in the center of a rod-shaped ceramic, a coil is wound around the outer periphery of the ceramic, and a voltage or current induced in the coil when a high-frequency electric field is applied to the antenna. Patent Document 1 discloses a technique for detecting the amount of water around by measuring. In this technique, an oscillator is connected to the antenna, and a measuring instrument such as an AC voltmeter is connected to the coil via a lead wire, so that a high-frequency electric field is applied to the antenna and the voltage or current induced in the coil is reduced. Will be measured.

  Also, by laminating a dielectric material such as ceramic on a plate-shaped conductor, placing a strip conductor on it, and measuring the electromagnetic wave loss when electromagnetic waves such as microwaves are passed through the strip conductor, Japanese Patent Application Laid-Open No. 2004-26883 discloses a technique for detecting the above. In this technique, an electromagnetic wave loss when an electromagnetic wave is passed through the strip conductor can be measured by connecting an oscillator or the like that applies an electromagnetic wave to the strip conductor and connecting a measuring device to the plate-like conductor.

  In the above-described technology, a transmitting-side conductor such as an antenna for applying an electromagnetic wave to a dielectric material such as a ceramic, and a receiving-side for detecting a current flowing in the dielectric such as a ceramic by the applied electromagnetic wave. It is necessary to draw out the wiring for connecting to the oscillator and the measuring instrument from each of the conductors. However, in that case, moisture may enter through a gap generated between the object to be measured and the wiring, and the measurement accuracy may be reduced.

  Therefore, it is considered to add an antenna for non-contact communication and an IC chip for performing non-contact communication via the antenna to the configuration as described above and transmit the detection result in a non-contact manner. By adopting such a configuration, it is possible to avoid the need for wiring and to prevent the measurement accuracy from being lowered due to moisture entering from a gap generated between the object to be measured and the wiring.

JP 56-33532 A Japanese Patent No. 4194179

  However, as described above, when an antenna for non-contact communication and an IC chip that performs non-contact communication via the antenna are added, the current flowing through the sensor unit made of a dielectric material such as a non-contact communication antenna and ceramics Since the electrodes for detecting each of them are made of conductors, they interfere with each other, and the current flowing through the antenna and the current flowing through the sensor cancel each other, resulting in unstable sensor performance and communication performance. End up.

  In order to avoid the above interference, it is necessary to separate the antenna and the electrode by a quarter wavelength or more of the communication frequency by the antenna. For example, the communication frequency is generally used for a non-contact communication medium. In the case of 920 MHz, it has to be separated by about 8 cm or more, and there is a problem that the shape becomes large.

  The present invention has been made in view of the problems of the conventional techniques as described above, and can accurately detect changes in the environment such as moisture without contact without increasing the size. An object is to provide a non-contact communication medium.

In order to achieve the above object, the present invention provides:
An antenna through which current flows by non-contact power supply;
An IC chip that performs non-contact communication via the antenna by supplying a current flowing through the antenna;
A sensor unit made of a dielectric;
A pair of electrodes attached to the sensor unit so as to face each other at a predetermined interval;
A sensor value detection unit that detects a resistance value of the sensor unit calculated by a current flowing between the pair of electrodes as a sensor value, converts the sensor value into a digital value, and outputs the digital value to the IC chip;
The antenna and the pair of electrodes are arranged such that the direction of the current flowing through the antenna and the direction of the current flowing between the pair of electrodes form a relative angle that is not parallel.

  In the present invention configured as described above, when a current flows to the antenna by non-contact power feeding, this current is supplied to the sensor value detection unit via the IC chip, and a predetermined interval is provided to the sensor unit made of a dielectric. A resistance value of the sensor unit calculated by a current flowing between a pair of electrodes attached to face each other is detected as a sensor value. The detected sensor value is converted into a digital value by the sensor value detection unit, output to the IC chip, and transmitted in a non-contact manner via the antenna. At this time, each of the antenna and the electrode is made of a conductor through which a current flows, but the direction of the current flowing through the antenna and the direction of the current flowing between the pair of electrodes form a relative angle that is not parallel. Therefore, the current flowing through the antenna and the current flowing through the sensor unit are difficult to cancel each other, and even if the antenna and the sensor unit are brought close to each other, sensor performance and communication performance may become unstable. Therefore, it is possible to accurately detect changes in the environment such as moisture without contact without increasing the size.

  Further, if the sensor unit is provided so as to face at least a part of the antenna, the sensor unit can shift the resonance frequency to the low frequency side to obtain a wavelength shortening effect. The overall size can be further reduced.

  According to the present invention, the antenna and the pair of electrodes are arranged such that the direction of the current flowing through the antenna and the direction of the current flowing between the pair of electrodes form a relative angle that is not parallel to each other. The current flowing in the sensor and the current flowing in the sensor section are difficult to cancel each other, so that changes in the environment such as moisture can be accurately detected without contact without increasing the size.

  Further, in the case where the sensor unit is provided so as to face at least a part of the antenna, a wavelength shortening effect is obtained by shifting the resonance frequency to the low frequency side by the sensor unit. Further downsizing can be realized.

It is a figure which shows one Embodiment of the non-contact communication medium of this invention, (a) is a surface view, (b) is the side view seen from the arrow A direction shown to (a), (c) is (a) (D) is a figure which shows the structure of the back surface of a sensor part, (e) is a figure which shows the structure on a base base material. It is a figure for demonstrating the effect | action of the moisture detection tag shown in FIG. It is a figure for demonstrating the effect by the sensor part being laminated | stacked facing the antenna in the moisture detection tag shown in FIG. It is a figure which shows other embodiment of the non-contact communication medium of this invention, (a) is a surface view, (b) is the side view seen from the arrow A direction shown to (a), (c) is ( It is the side view seen from the arrow B direction shown to a).

  Embodiments of the present invention will be described below with reference to the drawings.

  1A and 1B are diagrams showing an embodiment of a non-contact communication medium of the present invention, in which FIG. 1A is a front view, FIG. 1B is a side view seen from the direction of arrow A shown in FIG. (A) is a side view seen from the direction of arrow B shown in (a), (d) is a diagram showing the configuration of the back surface of the sensor unit 20, and (e) is a diagram showing the configuration on the base substrate 10.

  As shown in FIG. 1, this embodiment is a moisture detection tag 1 configured by stacking a sensor unit 20 on a base substrate 10.

  The base substrate 10 has a rectangular shape, and antennas 12a and 12b for non-contact communication are formed on one surface thereof, and an IC chip 11 that performs non-contact communication via the antennas 12a and 12b is provided. It is installed. Each of the antennas 12a and 12b is a dipole antenna made of copper foil and having a length of 70 mm. The base substrate 10 is aligned in a straight line with a predetermined interval so as to extend in the longitudinal direction of the base substrate 10. Formed on top. The IC chip 11 is connected to opposite ends of the antennas 12a and 12b. For example, the IC chip 11 performs contactless communication via the antennas 12a and 12b using a resonance frequency of 920 MHz. It is possible to use ANDY100.

The sensor unit 20 is made of, for example, ceramic mainly composed of kaolin (SiO ₂ : 70%), the length in the longitudinal direction is equal to the length in the longitudinal direction of the base substrate 10, and the length in the short direction is the base group. The material 10 has a rectangular shape shorter than the length in the short direction. The sensor unit 20 is laminated on the surface of the base substrate 10 on which the antennas 12a and 12b are formed so as to face the antennas 12a and 12b. Sensor electrodes 21a and 21b serving as a pair of electrodes having a thickness of 50 nm are formed by gold vapor deposition on both ends in the short direction of the sensor unit 20, respectively. Thereby, sensor electrode 21a, 21b has opposed in the direction orthogonal to the direction where antenna 12a, 12b is extended. In addition, a sensor circuit 22 serving as a sensor value detection unit is disposed on the surface of the sensor unit 20 that is laminated with the base substrate 10 so as to cover the IC chip 11, and the sensor circuit 22 and the IC chip 11 are Are electrically connected by a through hole (not shown) or the like. The sensor circuit 22 is connected to the sensor electrodes 21a and 21b via connection wirings 23a and 23b. For example, the sensor circuit 22 applies an electromagnetic wave of 1 kHz to the sensor electrodes 21a and 21b, and flows between the sensor electrodes 21a and 21b by the electromagnetic waves. The resistance value of the sensor unit 20 calculated using the current is detected as a sensor value, and the detected sensor value is converted into a digital value by a microcomputer and output to the IC chip 11.

  Below, operation | movement of the moisture detection tag 1 comprised as mentioned above is demonstrated.

  When the external device is put on the moisture detection tag 1 in a state where the moisture detection tag 1 shown in FIG. 1 is attached to an object to detect moisture, the antennas 12a and 12b are fed by non-contact power feeding from the external device. When the current flows to the IC chip 11, the moisture detection tag 1 is activated.

  When the moisture detection tag 1 is activated, an electromagnetic wave of 1 kHz is applied to the sensor electrodes 21 a and 21 b from the sensor circuit 22 connected to the IC chip 11, thereby causing a current to flow between the sensor electrodes 21 a and 21 b in the sensor unit 20. Flowing.

  In the sensor circuit 22, the resistance value of the sensor unit 20 is detected as a sensor value based on the current flowing between the sensor electrodes 21a and 21b in the sensor unit 20. Since the sensor unit 20 is made of ceramic and its resistance value changes according to the moisture content, the resistance value can be used as a sensor value.

  The sensor value detected by the sensor circuit 22 is converted into a digital value by the sensor circuit 22 and output to the IC chip 11.

  Since the sensor value output to the IC chip 11 is converted to a digital value, it is transmitted in a non-contact manner to the external device via the antennas 12a and 12b, and is transmitted in a non-contact manner from the moisture detection tag 1 in the external device. By receiving the sensor value, the moisture of the object to be measured to which the moisture detection tag 1 is attached is recognized.

  As described above, the non-contact communication antennas 12a and 12b and the IC chip 11 that performs non-contact communication via the antennas 12a and 12b are included, and the sensor value based on the analog value detected by the sensor circuit 22 is digital. Since it is converted into a value and output to the IC chip 11, even when moisture is detected using the sensor unit 20 made of ceramic, it is possible to detect moisture without connecting a cable or the like to the measuring instrument. It becomes.

  Here, as described above, in order to detect moisture in a non-contact manner, antennas 12a and 12b for non-contact communication are required. However, current flows through each of the antennas 12a and 12b and the sensor electrodes 21a and 21b. Since the antennas 12a and 12b and the sensor electrodes 21a and 21b interfere with each other because they are made of a conductor, the current flowing through the antennas 12a and 12b and the current flowing through the sensor unit 20 cancel each other, so that the sensor performance and the communication performance are improved. There is a risk of becoming unstable.

  FIG. 2 is a diagram for explaining the operation of the moisture detection tag 1 shown in FIG.

  In the moisture detection tag 1 shown in FIG. 1, when non-contact power feeding is performed from an external device, the antennas 12a and 12b are connected to the antennas 12a and 12b in the direction in which the antennas 12a and 12b extend, that is, the base base. A current flows in the direction of arrow A in FIG.

  On the other hand, when an electromagnetic wave of 1 kHz is applied to the sensor electrodes 21a and 21b from the sensor circuit 22, the sensor electrodes 21a and 21b are opposed to each other between the sensor electrodes 21a and 21b of the sensor unit 20 in the direction of arrow B in FIG. Current flows.

  At this time, as described above, the sensor electrodes 21a and 21b face each other in a direction orthogonal to the direction in which the antennas 12a and 12b extend, so that the direction of the current flowing through the antennas 12a and 12b and the sensor electrodes 21a and 21b The direction of the current flowing between 21b is orthogonal.

  Accordingly, even if the sensor unit 20 is disposed in the vicinity of the antennas 12a and 12b, such as by stacking the sensor unit 20 so as to face the antennas 12a and 12b, the current flowing in the antennas 12a and 12b and the sensor unit 20 The currents flowing between the sensor electrodes 21a and 21b do not cancel each other, and moisture can be accurately detected without contact without increasing the size of the moisture detection sensor 1.

  In the present embodiment, the sensor electrodes 21a and 21b face each other in a direction orthogonal to the direction in which the antennas 12a and 12b extend, so that the direction of the current flowing through the antennas 12a and 12b and the sensor electrodes 21a and 21b. The direction of the current flowing between the sensor electrodes 21a and 21b and the antennas 12a and 12b is the current flowing between the sensor electrodes 21a and 21b. If the directions are arranged so as to form a relative angle that is not parallel, the above-described action can be produced. However, as the direction of the current flowing through the antennas 12a and 12b and the direction of the current flowing between the sensor electrodes 21a and 21b become parallel, the current flowing between the sensor electrodes 21a and 21b cancels out in the sensor unit 20. Fades. Therefore, the sensor electrodes 21a and 21b and the antennas 12a and 12b are arranged such that the direction of the current flowing through the antennas 12a and 12b and the direction of the current flowing between the sensor electrodes 21a and 21b form a relative angle of 45 degrees to 135 degrees. The sensor electrodes 21a and 21b and the antennas 12a and 12b are preferably arranged so that the direction of the current flowing through the antennas 12a and 12b and the direction of the current flowing between the sensor electrodes 21a and 21b are 60 degrees to 120 degrees. More preferably, they are arranged so as to form a relative angle.

  Here, the effect by the sensor unit 20 being laminated facing the antennas 12a and 12b will be described.

  FIG. 3 is a diagram for explaining an effect obtained by stacking the sensor unit 20 facing the antennas 12a and 12b in the moisture detection tag 1 shown in FIG.

  As shown in FIG. 3A, similarly to the moisture detection tag 1 shown in FIG. 1, non-contact communication dipole antennas 12a and 12b made of copper foil are formed on the base substrate 10, and the IC The communication distance at a predetermined resonance frequency of the tag on which the chip 11 is mounted and the antenna 12a, 12b has a length L1 of 140 mm was 3.3 m.

  As shown in FIG. 3 (b), a ceramic 220a having a dielectric constant of 10 and a dielectric loss tangent of 0.03 is applied to the tag having this configuration, as shown in FIG. 3B, similar to the sensor unit 20 of the moisture detection tag 1 shown in FIG. When the base material 10 is laminated on the surface opposite to the surface on which the antennas 12a and 12b are formed, the resonance frequency is shifted to the low frequency side by the ceramic 220a, so that the wavelength shortening effect is obtained. The length L2 of the antennas 12a and 12b for non-contact communication at the resonance frequency can be reduced to 114 mm. When the communication distance in that case was measured, it was 3.3 m, and there was no change.

  Further, as shown in FIG. 3C, the antennas 12a and 12b of the base substrate 10 are made of ceramic 220b having a dielectric constant of 10 and a dielectric loss tangent of 0.03 with respect to the tag shown in FIG. When laminated on the formed surface, the resonance frequency is further shifted to the lower frequency side by the ceramic 220b, so that a wavelength shortening effect is obtained, whereby the antennas 12a, 12b for performing contactless communication at the same resonance frequency. The length L3 of 12b can be shortened to 100 mm. When the communication distance in that case was measured, it was 3.3 m, and there was no change.

  Thus, when the antennas 12a and 12b are opposed to the ceramic, the lengths of the antennas 12a and 12b can be shortened by the wavelength shortening effect, and the entire moisture detection tag 1 can be miniaturized. In addition, such an effect is acquired not only when the sensor part 20 is facing the whole antenna 12a, 12b but by facing at least one part of the antenna 12a, 12b.

(Other embodiments)
4A and 4B are diagrams showing another embodiment of the non-contact communication medium of the present invention, where FIG. 4A is a front view, FIG. 4B is a side view seen from the direction of arrow A shown in FIG. c) is a side view seen from the direction of arrow B shown in FIG.

  As shown in FIG. 4, the present embodiment is a moisture detection tag 101 configured by laminating a base substrate 110 on a sensor unit 120.

  The sensor unit 120 is made of the same material as the sensor unit 20 shown in FIG. 1 and has the same shape. Similarly to the sensor unit 20 shown in FIG. 1, sensor electrodes 121a and 121b having a thickness of 50 nm are formed on both ends in the short direction of the sensor unit 120 by gold vapor deposition.

  The base substrate 110 has the same shape as the base substrate 10 shown in FIG. 1, and a sensor circuit 122 serving as a sensor value detection unit is laminated on one surface and IC chip 111 is mounted on.

  The IC chip 111 is connected to non-contact communication antennas 112a and 112b made of the same material as the antennas 12a and 12b shown in FIG. 1 and having the same length. Similarly to the antennas 12a and 12b shown in FIG. 1, the antennas 112a and 112b are arranged in a straight line with a predetermined interval so as to extend in the longitudinal direction of the base substrate 110, and the whole of the antennas 112a and 112b is arranged. It faces the sensor unit 120. Thus, the antennas 112a and 112b are arranged so that the direction in which the antennas 112a and 112b extend is orthogonal to the direction in which the sensor electrodes 121a and 121b face each other. Similarly to the IC chip 11 shown in FIG. 1, the IC chip 111 performs non-contact communication via the antennas 112a and 112b, for example, using a resonance frequency of 920 MHz.

  Similarly to the sensor circuit 22 shown in FIG. 1, the sensor circuit 122 is connected to the sensor electrodes 121a and 121b via connection wires 123a and 123b. For example, an electromagnetic wave of 1 kHz is applied to the sensor electrodes 121a and 121b. The resistance value of the sensor unit 120 calculated using the current flowing between the sensor electrodes 121a and 121b by the electromagnetic wave is detected as a sensor value. The sensor circuit 122 is electrically connected to the IC chip 111 through a through hole (not shown) or the like, and converts the detected sensor value into a digital value by a microcomputer and outputs the digital value to the IC chip 111.

  Also in the moisture detection tag 101 configured as described above, the direction in which the antennas 112a and 112b extend is orthogonal to the direction in which the sensor electrodes 121a and 121b face each other, so that the current flowing through the antennas 112a and 112b. And the direction of the current flowing between the sensor electrodes 121a and 121b are orthogonal to each other, so that even if the sensor unit 120 is disposed in the vicinity of the antennas 112a and 112b, the current flowing through the antennas 112a and 112b and the sensor The current flowing between the sensor electrodes 121a and 121b does not cancel each other at the portion 120, and moisture can be detected accurately in a non-contact manner without increasing the size of the moisture detection sensor 101.

  In the above-described embodiment, the configuration in which the IC chips 11 and 111 and the sensor circuits 22 and 122 are stacked is described as an example. However, the IC chips 11 and 111 and the sensor circuits 22 and 122 are described as examples. 122 may be arranged on one substrate.

  Moreover, in embodiment mentioned above, although the sensor parts 20 and 120 detect the moisture content of a to-be-measured object using that the resistance value changes according to moisture content, a sensor part However, if the resistance value also changes due to temperature change or gas generation, the temperature change or gas generation can be detected by detecting the resistance value of the sensor unit.

  In addition, the sensor units 20 and 120 have been described by taking ceramics as an example. However, as long as it is a dielectric whose resistance value changes due to environmental changes such as moisture, the sensor unit is included in the non-contact communication medium of the present invention. Can be applied as

DESCRIPTION OF SYMBOLS 1,101 Moisture detection tag 10,110 Base base material 11,111 IC chip 12a, 12b, 112a, 112b Antenna 20,120 Sensor part 21a, 21b, 121a, 121b Sensor electrode 22,122 Sensor circuit 23a, 23b, 123a, 123b Connection wiring 220a, 220b Ceramic

Claims (2)

An antenna through which current flows by non-contact power supply;
An IC chip that performs non-contact communication via the antenna by supplying a current flowing through the antenna;
A sensor unit made of a dielectric;
A pair of electrodes attached to the sensor unit so as to face each other at a predetermined interval;
A sensor value detection unit that detects a resistance value of the sensor unit calculated by a current flowing between the pair of electrodes as a sensor value, converts the sensor value into a digital value, and outputs the digital value to the IC chip;
The non-contact communication medium in which the antenna and the pair of electrodes are arranged such that a direction of a current flowing through the antenna and a direction of a current flowing between the pair of electrodes form a relative angle that is not parallel to each other. The contactless communication medium according to claim 1,
The sensor unit is a non-contact communication medium provided to face at least a part of the antenna.

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