JP2017102028A - Moisture detection rfid tag and diaper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture detection RFID tag that can detect moisture with high sensitivity.SOLUTION: The moisture detection RFID tag comprises: an RFIC element including a first input/output terminal and a second input/output terminal; an antenna element including a first radiation electrode connected to the first input/output terminal and a second radiation electrode connected to the second input/output terminal; and a capacitor element series connected between the first radiation electrode and the second radiation electrode, and connected in parallel to the RFIC element. The capacitor element includes a pair of capacitor electrodes and a water absorption material held between the pair of capacitor electrodes. A change in dielectric constant caused by water absorption of the water absorption material is outputted as a change in communication distance or signal strength.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a moisture detection RFID tag capable of detecting the presence of moisture and a diaper using the same.

  Conventionally, in order to detect the presence of moisture, it has been necessary to use expensive components such as a humidity detecting semiconductor sensor.

  On the other hand, a wireless IC device that more easily detects the presence or absence of moisture has been proposed (see, for example, Patent Document 1). In this wireless IC device, an insulating material is interposed between the power supply circuit board and the antenna, and when the humidity rises, the degree of coupling between the power supply circuit board and the antenna changes and the communicable distance changes. Humidity is detected.

Japanese Patent No. 5182431

  Examples of the insulating material include an epoxy resin in which cellulose is dispersed and an epoxy resin in which polyvinyl alcohol is dispersed. However, since these materials have a small volume change with respect to the amount of moisture and the use area of the insulating material is limited, the detection sensitivity for the presence or absence of moisture is not sufficient.

  An object of the present invention is to provide a moisture detection RFID tag that can detect moisture with high sensitivity.

An RFID tag for moisture detection according to the present invention includes an RFIC element having a first input / output terminal and a second input / output terminal;
An antenna element having a first radiation electrode connected to the first input / output terminal and a second radiation electrode connected to the second input / output terminal;
A capacitor element connected in series between the first radiation electrode and the second radiation electrode and connected in parallel to the RFIC element;
With
The capacitor element is
A pair of capacitor electrodes;
A water absorbing material sandwiched between the pair of capacitor electrodes;
Have
A change in dielectric constant due to water absorption of the water absorbing material is output as a change in communication distance or signal intensity.

  The moisture detection RFID tag according to the present invention can detect moisture with high sensitivity.

(A) is a sectional side view of the RFID tag for moisture detection which concerns on Embodiment 1, (b) is a bottom view. (A) is a schematic sectional drawing which shows the cross-sectional structure of the RFIC element used for the RFID tag for moisture detection which concerns on Embodiment 1, (b) is an equivalent circuit schematic of (a). FIG. 3 is an equivalent circuit diagram as a whole of the moisture detection RFID tag according to the first embodiment. Frequency and transmission before providing the capacitor element of the RFID tag for moisture detection according to the first embodiment (A), after providing the capacitor element (B), and after absorbing water in the water absorbing material (C) It is a graph which shows an example of the relationship with an output. It is the schematic which shows the outline | summary of communication with the RFID tag for moisture detection contained in the diaper with the RFID tag for moisture detection which concerns on Embodiment 1. FIG. It is a schematic sectional drawing which shows the structural example of the RFID tag for a moisture detection contained in the diaper with the RFID tag for a moisture detection which concerns on Embodiment 1. FIG. It is a flowchart of the diaper replacement | exchange method using the diaper with the RFID tag for moisture detection which concerns on Embodiment 1. FIG. (A) is a sectional side view of the RFID tag for moisture detection which concerns on Embodiment 2, (b) is a bottom view. (A) is a sectional side view of the RFID tag for moisture detection which concerns on Embodiment 3, (b) is a bottom view. (A) is a sectional side view of the RFID tag for moisture detection which concerns on Embodiment 4, (b) is a bottom view. (A) is a sectional side view of the RFID tag for moisture detection which concerns on Embodiment 5, (b) is a bottom view. (A) is a sectional side view of the RFID tag for moisture detection which concerns on Embodiment 6, (b) is a bottom view. FIG. 10 is a bottom view of a moisture detection RFID tag according to a modification of the sixth embodiment. FIG. 10 is a schematic cross-sectional view illustrating a configuration example of a moisture detection RFID tag included in a diaper with a moisture detection RFID tag according to a seventh embodiment. (A) is the figure seen from the outer surface side of the waterproof material of the diaper which attached | subjected the position mark which mounts the RFID tag for using for the diaper with the RFID tag for moisture detection of FIG. 14, (b) is (a) It is the figure seen from the inner surface side of the waterproof material of a diaper.

The moisture detection RFID tag according to the first aspect includes an RFIC element having a first input / output terminal and a second input / output terminal;
An antenna element having a first radiation electrode connected to the first input / output terminal and a second radiation electrode connected to the second input / output terminal;
A capacitor element connected in series between the first radiation electrode and the second radiation electrode and connected in parallel to the RFIC element;
With
The capacitor element is
A pair of capacitor electrodes;
A water absorbing material sandwiched between the pair of capacitor electrodes;
Have
A change in dielectric constant due to water absorption of the water absorbing material is output as a change in communication distance or signal intensity.

  According to the above configuration, a change in dielectric constant due to water absorption to the water absorbing material of the capacitor element can be output as a change in communication distance or signal strength. Therefore, by detecting a change in communication distance or signal intensity corresponding to the reading distance, it is possible to know the water absorption state of the moisture detection RFID tag.

The RFID tag for moisture detection according to a second aspect further includes a counter electrode disposed opposite to at least a part of the first radiation electrode and the second radiation electrode in the first aspect,
The pair of capacitor electrodes may be configured by the at least part of the first radiation electrode and the second radiation electrode and the counter electrode.

  In the moisture detection RFID tag according to a third aspect, in the second aspect, the water absorbing material may have an exposed portion that is not covered by the counter electrode when viewed from the stacking direction with the counter electrode. Good.

  The RFID tag for moisture detection according to a fourth aspect is the communication distance after water absorption of the water absorbent material in any of the first to third aspects, rather than the communication distance or signal strength of the water absorbent material before water absorption. Alternatively, the signal intensity may be reduced.

The diaper with an RFID tag for moisture detection according to the fifth aspect is
Waterproof material provided on the outer surface;
A water absorbing material provided on the inner surface side of the waterproof material;
An RFID tag for moisture detection provided adjacent to the water absorbing material;
With
The moisture detection RFID tag is:
An RFIC element having a first input / output terminal and a second input / output terminal;
An antenna element having a first radiation electrode connected to the first input / output terminal and a second radiation electrode connected to the second input / output terminal;
A capacitor element connected in series between the first radiation electrode and the second radiation electrode and connected in parallel to the RFIC element;
With
The capacitor element is
A pair of capacitor electrodes;
A water absorbing material sandwiched between the pair of capacitor electrodes;
Have
A change in dielectric constant due to water absorption of the water absorbing material is output as a change in communication distance or signal intensity.

The moisture detection RFID tag diaper according to a sixth aspect further includes a counter electrode disposed opposite to at least a part of the first radiation electrode and the second radiation electrode in the fifth aspect,
The pair of capacitor electrodes may be configured by the at least part of the first radiation electrode and the second radiation electrode and the counter electrode.

The moisture detection RFID tag diaper according to a seventh aspect is the above sixth aspect, wherein the counter electrode is disposed on the inner surface side of the waterproof material of the diaper,
The second water absorbing material is common to the first water absorbing material,
The RFIC element and the antenna element may be disposed on the outer surface side of the waterproof material of the diaper.

A diaper with a moisture detection RFID tag according to an eighth aspect is provided on the outer surface, a waterproof material having a mark indicating a location where the antenna element of the moisture detection RFID tag is disposed,
A water absorbing material provided on the inner surface side of the waterproof material;
On the inner surface side of the water absorbing material, a counter electrode disposed to face the mark of the waterproof material,
With
The water absorbing material sandwiched between the antenna element, the counter electrode, and the antenna element and the counter electrode by disposing the antenna element of the RFID tag on the mark on the outer surface side of the waterproof material The capacitor element is configured by the above.

  Hereinafter, a moisture detection RFID tag and a diaper with a moisture detection RFID tag according to an embodiment will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1A is a side sectional view of the moisture detection RFID tag 10 according to the first embodiment, and FIG. 1B is a bottom view.
The moisture detection RFID tag 10 according to the first embodiment includes an RFIC element 1, an antenna element, and a capacitor element 16. The RFIC element 1 has a first input / output terminal 26a and a second input / output terminal 26b. The antenna element has a first radiation electrode 11 connected to the first input / output terminal 26a and a second radiation electrode 12 connected to the second input / output terminal 26b. In other words, each radiation electrode constitutes an electric field antenna having one end having a feeding end and the other end having an open end. The capacitor element is connected in series between the power supply end of the first radiation electrode 11 and the power supply end of the second radiation electrode 12, and is connected in parallel to the RFIC element 1. Further, the capacitor element 16 includes a pair of capacitor electrodes (first radiating electrode 11 and counter electrode 13, and second radiating electrode 12 and counter electrode 13), and a pair of capacitor electrodes (first radiating electrode 11 and counter electrode 13). And a water absorbing material 14 sandwiched between the second radiation electrode 12 and the counter electrode 13). The moisture detection RFID tag 10 is configured to output a change in dielectric constant due to water absorption of the water absorbing material 14 as a change in communication distance or signal intensity.

  According to the RFID tag 10 for moisture detection, a change in dielectric constant due to water absorption of the capacitor element 16 to the water absorbing material 14 can be output as a change in communication distance or signal intensity. Therefore, it is possible to know the water absorption state of the moisture detection RFID tag 10 by detecting a change in communication distance or signal intensity corresponding to the reading distance. That is, the tag 10 according to the first embodiment is not provided with an expensive sensor element such as a humidity sensor, but utilizes a change in capacitance between radiation electrodes that constitute an impedance matching circuit between the antenna element and the RFIC element. Thus, the tag can detect a change in the amount of water between the radiation electrodes as a change in the communication distance or signal intensity of the tag.

  The components of the moisture detection RFID tag 10 will be described below.

<RFIC element>
FIG. 2A is a schematic cross-sectional view showing a cross-sectional structure of the RFIC element 1, and FIG. 2B is an equivalent circuit diagram of FIG.
The RFIC element 1 is configured as an RFIC package having an RFIC chip 21 that processes an RFID signal and a multilayer substrate 25 on which the RFIC chip 21 is mounted. The RFIC chip 21 may include a memory circuit or a signal processing circuit and may be sealed with an epoxy resin sealing resin 24 or the like. The RFIC chip 21 is mounted on a multilayer substrate 25 that constitutes a power feeding circuit via a conductive bonding material 22 and a terminal electrode 23. The power feeding circuit may be formed in a multilayer substrate shape.
The multilayer substrate 25 is a ceramic multilayer substrate made of a ceramic material such as LTCC, and an element constituting a power feeding circuit such as an L pattern constituting the inductors L1 and L2 and a C pattern constituting the capacitors C1 and C2. Is built-in. The inductor L1 and the inductor L2 have different inductance values and are magnetically coupled via a mutual inductance M. In terms of an equivalent circuit, the power supply circuit further includes a capacitor C _IC . The capacitor C _IC is the stray capacitance of the RFIC chip 21 itself. Feed circuit includes mainly the inductors L1 and L2, a resonance circuit constituted by the capacitor _{C IC.} The resonance frequency of this resonance circuit corresponds to the carrier frequency. By providing the feeding circuit in this way, the center frequency of the carrier frequency can be prevented from changing greatly even if the electrical length of the antenna element having the first radiating electrode 11 and the second radiating electrode 12 changes. The multilayer substrate 25 is connected to the first radiation electrode 11 and the second radiation electrode 12 via the terminal electrodes 26a and 26b, respectively.

<Antenna element>
The antenna element is a dipole antenna including a first radiation electrode 11 and a second radiation electrode 12. The first radiating electrode 11 and the second radiating electrode 12 are connected to the RFIC element at the feeding end on one end side, respectively, and the other end side forms an open end, respectively, extending from the RFIC element 1 in opposite directions. Exist. A capacitor element 16 is connected in series between the first radiation electrode 11 and the second radiation electrode 12.
For example, in FIG. 1A, the RFIC element 1 and the first radiation electrode 11 and the second radiation electrode 12 are directly connected to the first input / output terminal 26a and the second input terminal 26b, respectively, in a direct current manner. Not limited to this. For example, the RFIC element 1 and the first radiation electrode 11 and the second radiation electrode 12 may be coupled by any combination such as capacitive coupling and magnetic field coupling instead of direct connection.

<Capacitor element>
FIG. 3 is an equivalent circuit diagram as a whole of the moisture detection RFID tag 10 according to the first embodiment.
As shown in the equivalent circuit diagram of FIG. 3, the capacitor element 16 is connected in series between the first radiation electrode 11 and the second radiation electrode 12, and is connected in parallel to the RFIC element 1. Capacitor element 16 has a pair of capacitor electrodes and a water absorbing material sandwiched between the pair of capacitor electrodes. That is, the capacitor element 16 is a moisture sensitive capacitor whose capacitance value changes depending on the degree of water absorption of the water absorbing material. The capacitor element 16 may be provided separately with respect to the antenna element, or the capacitor element 16 is configured by providing the counter electrode 13 disposed to face at least a part of the first radiation electrode 11 and the second radiation electrode 12. May be. In this case, the pair of capacitor electrodes is constituted by the feeding end portion of the first radiation electrode 11 and the feeding end portion of the second radiation electrode 12, and the counter electrode 13 facing the feeding end portion of each radiation electrode. Can do. Specifically, the first capacitor element can be constituted by an electrode that is a pair of the first radiation electrode 11 and the counter electrode 13. Further, the second capacitor element can be constituted by an electrode that is a pair of the second radiation electrode 12 and the counter electrode 13. There may be at least one capacitor element 16.
The capacitor element 16 constitutes a matching circuit for matching impedances of the RFIC element 1 with the first radiation electrode 11 and the second radiation electrode 12 together with the power feeding circuit.

<Counter electrode>
The counter electrode 13 is provided so as to face at least a part of the first radiation electrode 11 and the second radiation electrode 12. This counter electrode 13 is a copper foil, a copper plate, a copper plating film, a gold foil, a gold plate, a gold plating film, an aluminum foil, an aluminum plate, an aluminum film, a silver foil, a silver plate, a silver plating film, etc. Materials can be used. The material is not limited to the above example, and any material that is normally used can be used. Moreover, formation of a thin film etc. is not restricted to plating, You may use printing, vapor deposition, etc. Furthermore, you may comprise an electrode using an electroconductive fiber. For example, the counter electrode may be formed by vapor-depositing aluminum on a resin sheet or resin film such as polyethylene terephthalate (PET) as shown in the examples described later.

<Water absorbing material>
A continuous water-absorbing material 14 is sandwiched between the first radiation electrode 11 and the counter electrode 13 and between the second radiation electrode 12 and the counter electrode 13. As the water absorbing material 14, for example, a polymer water absorbing material (polymer water absorbing material) or the like can be used. An inorganic water-absorbing material can also be used. As the water absorbing material, it is preferable that the degree of water absorption is large. Here, the water absorbing material 14 is provided continuously between the first radiating electrode 11 and the counter electrode 13 and between the second radiating electrode 12 and the counter electrode 13, but is not limited thereto. You may provide a water absorbing material separately.

<Detection of water absorption state>
FIG. 4 shows a state before providing the capacitor element 16 of the moisture detection RFID tag 10 according to the first embodiment (A), after providing the capacitor element 16 (B), and after absorbing water into the water absorbing material 14 ( C) is a graph showing an example of the relationship between the frequency and the transmission output. The detection of the water absorption state by the moisture detection RFID tag 10 will be described with reference to FIG.
First, the moisture detection RFID tag 10 forms a matching circuit between the RFIC element 1, the antenna element including the first radiation electrode 11, and the second radiation electrode 12 even when the capacitor element 16 is not provided. The maximum transmission output is obtained at a predetermined frequency (FIG. 4: A). Further, when the capacitor element 16 is provided, the capacitor element 16 constitutes a matching circuit between the antenna element including the first radiation electrode 11 and the second radiation electrode 12. Also in this case, when the water absorbing material 14 is before water absorption, there is no significant change in the relationship between the frequency and the transmission output compared to before the capacitor element 16 is provided (FIG. 4: B).
On the other hand, the water absorption material 14 of the capacitor element 16 absorbs moisture, so that the capacitance between the first radiation electrode 11 and the counter electrode 13 and the capacitance between the second radiation electrode 12 and the counter electrode 13 are respectively reduced. Change. As a result, the relationship between the frequency and the transmission output changes greatly after the water absorption of the water absorbing material 14 before the water absorption, and the transmission output at the predetermined frequency is greatly reduced (FIG. 4: C). For example, it changes by 20 dBm or more in Example 1 described later. In this case, communication between the moisture detection RFID tag 10 and the reader / writer (R / W) becomes impossible. By detecting a change in transmission output at a predetermined frequency, the water absorption state of the water absorbing material 14 of the moisture detection RFID tag 10 can be detected. Note that the relationship (A, B, C) between the frequency and the transmission output in FIG. 4 is an example, and is not limited to this.

In this case, a matching circuit is configured between the RFIC element 1, the antenna element including the first radiation electrode 11 and the second radiation electrode 12. Therefore, as long as the configuration of the capacitor element 16 does not greatly change the relationship between the frequency and the transmission output before the water absorbing material 14 absorbs water, the material, size, and the like of the water absorbing material 14 can be freely selected. Alternatively, a slight frequency shift may be caused by providing the capacitor element 16. If the frequency shift amount before water absorption by the capacitor element 16 is large and the transmission output before water absorption is greatly deteriorated, the center frequency that is optimal when the capacitor element 16 is added by changing the circuit constant in the RFID element or the like. so that can be obtained, but it may also be made design changes. Therefore, a material having good water absorption can be used as the water absorbing material 14, and good detection performance can be obtained. The counter electrode 13 may have a large area regardless of the size of the first radiation electrode 11, the second radiation electrode 12, and the RFIC element 1. As a result, the permissible range of the opposing positions of the first radiation electrode 11, the second radiation electrode 12, and the water absorbing material 14 is increased, so that alignment can be performed easily. Further, the water absorbing material 14 may have a large area regardless of the size of the first radiation electrode 11, the second radiation electrode 12, and the RFIC element 1. As a result, moisture around the moisture detection RFID tag 10 can be easily absorbed, and moisture can be detected with higher sensitivity.
As described above, according to the moisture detection RFID tag 10, it is possible to detect a water absorption state by detecting a change in transmission output at a predetermined frequency.

  Here, the case where the transmission output is maximum at a predetermined frequency before water absorption of the water absorbing material 14 and the transmission output decreases at the predetermined frequency after water absorption of the water absorbing material 14 has been described, but the present invention is not limited thereto. . For example, the transmission output may be low at a predetermined frequency before water absorption of the water absorbing material 14, and the transmission output may be increased at a predetermined frequency after water absorption of the water absorbing material 14. In the latter case, the water absorption state can be detected by detecting that the transmission output increases at a predetermined frequency after the water absorbing material 14 absorbs water.

Next, a diaper 30 with a moisture detection RFID tag using the moisture detection RFID tag 10 will be described.
FIG. 5 is a schematic diagram illustrating an outline of communication with the moisture detection RFID tag 10 included in the diaper 30 with moisture detection RFID tag according to the first embodiment. FIG. 6 is a schematic diagram showing a configuration of the diaper 30 with RFID tag for moisture detection according to the first embodiment.
In the detection of the water absorption state in the diaper 30 with moisture detection RFID tag, the moisture detection RFID tag 10 is attached to the diaper 30. Thereby, it is possible to know the water absorption state in the diaper by performing communication between the reader / writer 40 and the moisture detection RFID tag 10 and detecting a change in communication distance or signal intensity.

<Diaper with RFID tag for moisture detection>
The diaper 30 with moisture detection RFID tag includes a waterproof material 32 provided on the outer surface, water absorbing materials 34a and 34b provided on the inner surface side of the waterproof material 32, and moisture detection provided adjacent to the water absorbing material 34a. RFID tag 10 for use. The moisture detection RFID tag 10 is the same as the moisture detection RFID tag 10, and is connected to the RFIC element 1 having the first input / output terminal 26a and the second input / output terminal 26b, and the first input / output terminal 26a. An antenna element having the second radiation electrode 12 connected to the first radiation electrode 11 and the second input / output terminal 26b, and the first radiation electrode 11 and the second radiation electrode 12 connected in series; and And a capacitor element 16 connected in parallel to the RFIC element 1. The capacitor element 16 has a pair of capacitor electrodes (the first radiation electrode 11 and the counter electrode 13, the second radiation electrode 12 and the counter electrode 13), and the water absorbing material 14 sandwiched between the pair of capacitor electrodes. The moisture detection RFID tag 10 is configured to output a change in dielectric constant due to water absorption of the water absorbing material 14 as a change in communication distance or signal intensity.
The diaper 30 may constitute all or part of the diaper. Moreover, you may use this diaper 30 as a part of diaper, ie, an inner, or a pad. In this case, the inner diaper 30 can be replaced without replacing the outer.

  Below, the component of this diaper 30 is demonstrated.

<RFID tag for moisture detection>
Since the moisture detection RFID tag 10 is the same as the moisture detection RFID tag 10, the detailed description of its configuration is omitted.
In FIG. 6, the moisture detection RFID tag 10 is provided between the water absorbing material 34a and the water absorbing material 34b, but is not limited thereto. For example, the moisture detection RFID tag 10 may be provided between the waterproof material 32 and the water absorbing material 34a. In addition, since the diaper 30 may damage the human buttock 50 when it comes into direct contact with the human buttock 50, the diaper 30 is preferably disposed between the diaper 30 via the water absorbing material 34b.

<Diaper>
This diaper 30 may be either an integral diaper or a water absorbent material for diapers that is an inner (or pad) in the case of a diaper that is separated into an outer and an inner. Moreover, the diaper 30 may be any of infant diapers, adult urine leakage pants, urine leakage pads, nursing pants, nursing diapers, and the like. Furthermore, it may be a pet diaper. Or the water absorbing material for diapers which is these inner parts may be sufficient. The age and sex of the user and pet are not limited.

<Water absorbing material>
The water absorbing material 34a, 34b is a constituent element of the diaper 30, and a water absorbing material in which a polymer water absorbing material or the like is arranged can be used. As described above, the moisture detection RFID tag 10 used here may be disposed between the water absorbing material 34a and the water absorbing material 34b, or between the waterproof material 32 and the water absorbing material 34a.

<Waterproof material>
The waterproof material 32 can be used as long as it is provided so as not to wet the outer surface of the diaper 30. For example, a polyolefin film, a polyolefin nonwoven fabric, a polyester nonwoven fabric and the like can be used.

<Diaper changing method>
FIG. 7 is a flowchart of diaper replacement when the diaper 30 with the RFID tag for moisture detection shown in FIG. 6 is used.
(1) The care recipient himself / herself wears the moisture detecting RFID tag diaper 30 or the caregiver causes the care recipient to wear (S11).
(2) During regular diaper excursions, the caregiver reads the moisture detection RFID tag 10 with respect to the diaper 30 of the care recipient by using, for example, a smartphone-integrated reader 40 arranged at a fixed distance (S12). ). Note that the reader 40 is not limited to a smartphone-integrated reader, and may be a stationary reader. It may be a handy type reader that is not a smartphone-integrated type. Stationary readers include those that lay under the body of a lying caregiver, such as sheets and futons.
(3) After wearing the diaper, it is determined whether the time more than the specified time has passed (S13). If the time more than the specified time has passed, the caregiver removes the diaper 30 of the care recipient (S14). The care recipient wears a new diaper 30 fitted with the moisture detection RFID tag 10 or wears it (S15). Thereafter, the process returns to the reading of the moisture detection RFID tag 10 (S12).
In addition, if the time more than regulation has not passed, it will move to the following step S16.
By changing the diaper according to the time after wearing the diaper in this way, diaper rash, pressure ulcer, etc. can be prevented. For example, when using a diaper that can be absorbed multiple times, if the amount of urination is small, urine adhering to the diaper may touch the body for a long time and cause pressure ulcers and the like. Also, in cases such as “when urine has not been guided to the tag part due to posture” or “when the tag has been removed”, it is recommended to provide a “prescribed time” to promote diaper replacement. It is possible to prevent urine from leaking into the bed.
(4) It is determined whether the signal strength in communication with the moisture detection RFID tag 10 is equal to or higher than the threshold value (S16). If there is a signal strength equal to or higher than the threshold value (YES), the water absorbing material of the moisture detection RFID tag 10 14 indicates that no water is absorbed. That is, there is no moisture in the diaper 30 yet, the diaper is not changed (S17), and the RFID tag 10 is read back during regular patrol (S12).
On the other hand, when the signal intensity in communication with the moisture detection RFID tag 10 is less than the threshold value (NO), it is considered that the water absorbing material 14 is absorbing water. In this case, a considerable amount of water, i.e., urine or stool is present in the diaper 30. Accordingly, it can be determined that the allowable range is full or the allowable amount is exceeded, and the process proceeds to the next step S18.

(5) The caregiver removes the diaper 30 of the care recipient (S18), and the caregiver wears or wears a new diaper 30 with the moisture detection RFID tag 10 attached (S19).
(6) Immediately after changing the diaper, the moisture detection RFID tag 10 is read by the reader 40 arranged at a fixed distance from the diaper 30 (S20). Thereafter, the process proceeds to step S16 in which it is determined whether the signal intensity in communication with the moisture detection RFID tag 10 is equal to or higher than a threshold value. By thus reading the moisture detection RFID tag 10 immediately after changing the diaper, an initial failure of the moisture detection RFID tag 10 can be detected. In this case, the flow does not end even if the diaper is changed.
Note that the reading of the RFID tag 10 for moisture detection immediately after changing the diaper (S20) may not be performed, and the reading of the RFID tag 10 during the regular patrol may be returned (S12). That is, reading of the moisture detection RFID tag 10 immediately after the diaper replacement may be omitted.
As described above, the diaper can be exchanged by periodic patrol using the smart phone combined type reader 40. In this flowchart, the diaper replacement can be repeated as many times as necessary in accordance with the actual state.

  Here, a change in the wireless communication state is detected by determining whether the signal intensity from the RFID tag 10 for moisture detection is equal to or higher than a threshold value. Thereby, the water absorption state is detected. What is necessary is just to set the threshold value corresponding to the signal strength in permissible quantity so that diaper replacement | exchange may be performed when it becomes permissible quantity. Therefore, the wet state of the diaper 30 can be grasped more appropriately, and the necessity of diaper replacement can be determined more reliably. For example, when the moisture state in the diaper 30 is displayed, the wet state of the diaper 30 may be displayed numerically or visualized. For example, the wet state of the diaper 30 may be displayed by a plurality of color codes such as yellow and red so that it is easy to grasp the necessity of changing the diaper.

Note that here, the moisture detection RFID tag 10 is configured such that the communication distance or signal strength after water absorption of the water absorbing material 14 is smaller than the communication distance or signal strength of the water absorbing material 14 before water absorption. Explained. However, the present invention is not limited to this case, and conversely, for example, the moisture detection RFID tag 10 has a communication distance or signal strength after the water absorbing material 14 absorbs water larger than a communication distance or signal strength before the water absorbing material 14 absorbs water. It may be a case where it is constituted in this way.
Note that a series of steps S13 to S15 for determining whether a predetermined time or more has elapsed after the diaper is mounted is not essential, and may be performed as necessary.

As described above, since the moisture detection RFID tag 10 according to Embodiment 1 is attached to the diaper 30 and moisture can be detected, a wet state due to urine or stool or sweat can be detected. In addition, since the moisture detection RFID tag 10 is used, it is not necessary to use expensive parts such as a humidity detection semiconductor sensor, and it can be constructed at low cost. In addition, since the configuration itself is simple, the reliability is high. In addition, it is preferable that each water absorbing material 14 of the moisture detection RFID tag 10 has the same or higher water absorption as the water absorbing materials 34 a and 34 b of the diaper 30. If the water absorption of the water absorbent 14 is lower than that of the water absorbent 34a, 34b of the diaper 30, the water detection performance is degraded. However, if the use upper limit of the diaper is detected, the water absorbing material in the diaper absorbs the water up to the absorption limit, so that the water absorption of the water absorbing material 14 is absorbed by the water absorbing materials 34a and 34b of the diaper 30. be lower than the sex, the applications that detects the diaper use upper limit, Ru can be used effectively.

Example 1
The moisture detection RFID tag 10 according to a more specific example 1 will be described. In the moisture detection RFID tag 10, the counter electrode 13 was formed by depositing aluminum on polyethylene terephthalate (PET) having a size of 5 mm × 5 mm. Further, as the water absorbing material 14, a non-woven fabric made of cellulose / acrylic resin (pulp / acrylic ester copolymer) (Tricks HV30: manufactured by Hashimoto Cross Co., Ltd.) was used.
According to the moisture detection RFID tag 10 according to Example 1, the transmission output decreased by about 20 dBm or more after water absorption of the water absorbing material 14 compared to before water absorption of the water absorbing material 14 at the center frequency of communication. Since the water absorption material 14 absorbs moisture in this way, a large change in received power can be detected, so that the water absorption state can be detected with high sensitivity.

(Embodiment 2)
FIG. 8A is a side sectional view of the moisture detection RFID tag 10a according to the second embodiment, and FIG. 8B is a bottom view.
In comparison with the moisture detection RFID tag according to the first embodiment, the moisture detection RFID tag 10 a has the capacitor element 16 on the same side as the RFIC element 1 with respect to the first radiation electrode 11 and the second radiation electrode 12. It differs in that it is provided. That is, the counter electrode 13 and the water absorbing material 14 may be provided on the same side as the RFIC element 1 with respect to the first radiation electrode 11 and the second radiation electrode 12. The counter electrode 13 is provided above the RFIC element 1 and covers the RFIC element 1. Thereby, the RFIC element 1 can be protected. In addition, instead of the hard RFIC element 1, for example, a soft PET resin sheet or the like that functions as the counter electrode 13 can be disposed on the outer surface, so that the touch to human skin can be eased.

(Embodiment 3)
FIG. 9A is a side sectional view of the moisture detection RFID tag 10b according to the third embodiment, and FIG. 9B is a bottom view.
In contrast to the moisture detection RFID tag according to the first embodiment, the moisture detection RFID tag 10b is provided with a counter electrode 13 and a water absorbing material 14 so as to overlap the entire surface of the first radiation electrode 11 and the second radiation electrode 12. Is different. Thereby, the first radiation electrode 11 and the second radiation electrode 12 can be stably supported. Moreover, since the area of the water absorbing material 14 is maximized, a change in dielectric constant due to moisture absorption into the water absorbing material 14 becomes large, and moisture can be detected with higher sensitivity.
Here, the counter electrode 13 and the water absorbing material 14 are provided so as to overlap the entire surfaces of the first radiation electrode 11 and the second radiation electrode 12, but the present invention is not limited thereto. For example, the counter electrode and the water absorbing material may be provided so as to overlap only one of the first radiation electrode 11 and the second radiation electrode 12 without straddling the centers of the first radiation electrode 11 and the second radiation electrode 12. (Not shown).

(Embodiment 4)
FIG. 10A is a side sectional view of the moisture detection RFID tag 10c according to the fourth embodiment, and FIG. 10B is a bottom view. In addition, the side sectional view of FIG. 10A is a sectional view seen from the AA direction of FIG.
The moisture detection RFID tag 10 c is different from the moisture detection RFID tag according to the first embodiment in that at least one hole 17 is provided in the counter electrode 13. Since the water-absorbing material 14 can easily absorb moisture by the holes 17 provided in the counter electrode 13, the moisture can be detected with higher sensitivity.

(Embodiment 5)
FIG. 11A is a side sectional view of the moisture detection RFID tag 10d according to the fifth embodiment, and FIG. 11B is a bottom view. In addition, the side sectional view of FIG. 11A is a sectional view seen from the BB direction of FIG. 11B and shows a section of the slit 18.
This moisture detection RFID tag 10 d is different from the moisture detection RFID tag according to the first embodiment in that a slit 18 is provided in the counter electrode 13. Since the water is easily absorbed by the water absorbing material 14 by the slit 18 provided in the counter electrode 13, the moisture can be detected with higher sensitivity. A plurality of slits 18 may be provided.

(Embodiment 6)
FIG. 12A is a side sectional view of the moisture detection RFID tag 10e according to the sixth embodiment, and FIG. 12B is a bottom view.
When this moisture detection RFID tag 10e is compared with the moisture detection RFID tag according to the first embodiment, the water absorbing material 14 has an exposed portion that is not covered by the counter electrode 13 when viewed from the stacking direction with the counter electrode 13. Have. Specifically, it differs in that the water absorbing material 14 has a portion (exposed portion) that protrudes from the counter electrode 13. This makes it easier for the water-absorbing material 14 to absorb the moisture around the moisture-detecting RFID tag 10e, so that moisture can be detected with higher sensitivity. The water absorbing material 14 may be larger than the counter electrode 13. Alternatively, the water absorbing material 14 may have at least a portion that protrudes from the counter electrode 13. In this case, the water absorbing material 14 may be smaller in size than the counter electrode 13 except for a portion protruding from the counter electrode 13.

(Modification)
FIG. 13 is a bottom view of a moisture detection RFID tag 10f according to a modification of the sixth embodiment.
In comparison with the moisture detection RFID tag 10e according to the sixth embodiment, the moisture detection RFID tag 10f is further wider than the first radiation electrode 11 and the second radiation electrode 12 in which the counter electrode 13 is an antenna element. It is different in point. Thereby, even when there is a positional deviation between the counter electrode 13 and the first radiation electrode 11 and the second radiation electrode 12, the allowable range can be widened, and the fluctuation of the capacitance value of the capacitor element 16 can be suppressed. Therefore, there is an advantage that the allowable range of dimensions at the time of manufacture can be widened and the practical application can be easily performed. Moreover, since both the counter electrode 13 and the water absorbing material 14 are wider than the widths of the first radiation electrode 11 and the second radiation electrode 12, an allowable range with respect to the mutual displacement of the counter electrode 13 and the water absorbing material 14 can be increased.

(Embodiment 7)
<Diaper with RFID tag for moisture detection>
FIG. 14 is a schematic cross-sectional view showing a configuration example of a moisture detection RFID tag 10g included in the diaper 30a with moisture detection RFID tag according to the seventh embodiment. FIG. 15A is a development view of the diaper 30a with the position mark 36 for attaching the RFID tag for use in the moisture detecting RFID tag diaper 30a of FIG. 14 as viewed from the outer surface side of the waterproof material 32. FIG. FIG.15 (b) is the expanded view seen from the inner surface side of the waterproof material 32 of the diaper 30a of Fig.15 (a).
Compared with the moisture detection RFID tag according to the first embodiment, the moisture detection RFID tag 10g includes a water absorbing material 34a sandwiched between the first radiation electrode 11, the second radiation electrode 12, and the counter electrode 13. It differs from the water absorbing material 34a of the diaper 30a in that it is a constituent element of the diaper 30a. Further, the RFID tag including the counter electrode 13 and the water absorbing material 34a disposed on the inner surface side of the diaper 30a and including the RFIC element 1, the first radiating electrode 11, the second radiating electrode 12, and the counter electrode 13 is waterproof to the diaper 30a. It differs in that it is arranged on the outer surface side of the material 32. A capacitor element is configured by sandwiching a water absorbing material 34a between the first and second radiation electrodes 11 and 12 on the outer surface side of the waterproof material 32 of the diaper 30a and the counter electrode 13 on the inner surface side of the diaper 30a. Since this capacitor element uses the water absorbing material 34a which is a component of the diaper 30a as the water absorbing material, the dielectric constant changes due to the water absorption of the water absorbing material 34a. Thereby, the water | moisture content inside the diaper 30a is detectable with sufficient sensitivity. In addition, since the RFID tag is disposed on the outer surface side of the waterproof material 32 of the diaper 30a, the RFID tag itself does not get wet and can be used repeatedly.

In addition, as shown to Fig.15 (a), an RFID tag can be easily mounted | worn by using the diaper 30a which attached | subjected the position mark 36 which mounts the RFID tag 10 for a water | moisture content detection. In FIGS. 15A and 15B, the position mark 36 shows the shape of the counter electrode 13 as it is, but the present invention is not limited to this. The position mark 36 is not limited to the shape of the counter electrode 13, but may be a position mark such as a round shape or a cross shape so as to schematically represent the position of the counter electrode 13 or the position where the RFID tag is attached. Alternatively, as the position mark 36, a guide line indicating a position where the RFID tag is mounted may be provided.
Further, a water absorbing material 34 is disposed on the inner surface side of the diaper 30a, and the counter electrode 13 is inserted on the inner surface side of the water absorbing material 34. As the counter electrode 13, as described above, for example, a resin sheet or a resin film printed with conductive ink, a conductive material deposited, or a fiber or woven fabric in which conductive fibers are woven are used. It may be used.
Furthermore, by arranging the antenna elements of the RFID tag (first radiation electrode 11 and second radiation electrode 12) on the position mark 36 on the outer surface side of the waterproof material 32, a diaper 30a with a moisture detection RFID tag can be constructed. . Specifically, the antenna element (the first radiation electrode 11 and the second radiation electrode 12) disposed at the position mark 36, the counter electrode 13, and the water absorbing material 34 sandwiched between the antenna element and the counter electrode 13 Thus, the capacitor element 16 can be configured.

  In the above description, the application example of the diaper 30 that is attached to the diaper 30 as an application example of the moisture detection RFID tag 10 is described. However, the application example is not limited to the above application example. For example, it can be used as a water leak detection RFID tag in which a water detection RFID tag 10 is attached to the outside of a water pipe to detect water leak.

  The frequency band using the moisture detection RFID tag may be any band such as LF band, HF band, UHF band, and SHF band. The moisture detection RFID tag is not limited to a tag having a so-called tag function, and may have other functions such as a reader / writer function.

  It should be noted that the present disclosure includes appropriately combining any of the various embodiments and / or examples described above, and each of the embodiments and / or examples. The effect which an Example has can be show | played.

  According to the RFID tag for moisture detection according to the present invention, a change in dielectric constant due to water absorption to the water absorbing material of the capacitor element can be output as a change in communication distance or signal intensity. Therefore, it is possible to know the water absorption state of the moisture detection RFID tag by detecting a change in communication distance or signal intensity.

1 RFIC element 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g Moisture detection RFID tag 11 First radiation electrode 12 Second radiation electrode 13 Counter electrode 14 Water absorbing material (second water absorbing material)
16 Capacitor element 17 Hole 18 Slit 21 RFIC chip 22 Conductive bonding material 23 Terminal electrode 24 Sealing resin 25 Multilayer substrate 26a First input / output terminal (terminal electrode)
26b Second input / output terminal (terminal electrode)
30, 30a Diaper 32 Waterproof material 34a, 34b Water absorbing material (first water absorbing material)
36 RFID tag mounting position mark 40 reader / writer 50 buttocks

Claims (8)

An RFIC element having a first input / output terminal and a second input / output terminal;
An antenna element having a first radiation electrode connected to the first input / output terminal and a second radiation electrode connected to the second input / output terminal;
A capacitor element connected in series between the first radiation electrode and the second radiation electrode and connected in parallel to the RFIC element;
With
The capacitor element is
A pair of capacitor electrodes;
A water absorbing material sandwiched between the pair of capacitor electrodes;
Have
A moisture detection RFID tag configured to output a change in dielectric constant due to water absorption of the water absorbing material as a change in communication distance or signal intensity. A counter electrode disposed opposite to at least a part of the first radiation electrode and the second radiation electrode;
2. The RFID tag for moisture detection according to claim 1, wherein the pair of capacitor electrodes is configured by the at least a part of the first radiation electrode and the second radiation electrode and the counter electrode.   3. The moisture detection RFID tag according to claim 2, wherein the water absorbing material has an exposed portion that is not covered with the counter electrode when viewed from the stacking direction with the counter electrode.   4. The communication distance or signal strength after water absorption of the water absorbing material is configured to be smaller than the communication distance or signal strength of the water absorbing material before water absorption. 5. RFID tag for moisture detection. Waterproof material provided on the outer surface;
A first water-absorbing material provided on the inner surface side of the waterproof material;
An RFID tag for moisture detection provided adjacent to the water absorbing material;
With
The moisture detection RFID tag is:
An RFIC element having a first input / output terminal and a second input / output terminal;
An antenna element having a first radiation electrode connected to the first input / output terminal and a second radiation electrode connected to the second input / output terminal;
A capacitor element connected in series between the first radiation electrode and the second radiation electrode and connected in parallel to the RFIC element;
With
The capacitor element is
A pair of capacitor electrodes;
A second water-absorbing material sandwiched between the pair of capacitor electrodes;
Have
A diaper with a moisture detection RFID tag configured to output a change in dielectric constant due to water absorption of the second water absorbing material as a change in communication distance or signal intensity. A counter electrode disposed opposite to at least a part of the first radiation electrode and the second radiation electrode;
The diaper with a moisture detection RFID tag according to claim 5, wherein the pair of capacitor electrodes is constituted by the at least a part of the first radiation electrode and the second radiation electrode and the counter electrode. The counter electrode is disposed on the inner surface side of the waterproof material of the diaper,
The second water absorbing material is common to the first water absorbing material,
The diaper with a moisture detection RFID tag according to claim 6, wherein the RFIC element and the antenna element are arranged on an outer surface side of the waterproof material of the diaper. A waterproof material provided on the outer surface side and having a mark indicating a position where the antenna element of the RFID tag is disposed;
A water absorbing material provided on the inner surface side of the waterproof material;
On the inner surface side of the water absorbing material, a counter electrode disposed to face the mark of the waterproof material,
With
The water absorbing material sandwiched between the antenna element, the counter electrode, and the antenna element and the counter electrode by disposing the antenna element of the RFID tag on the mark on the outer surface side of the waterproof material A diaper for a diaper with an RFID tag for moisture detection, which constitutes a capacitor element.

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