JP2011067620A - Liquid detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid detection device permitting secure communication between a tag attached to the inside of a diaper and an antenna. <P>SOLUTION: The urine detection device 11 includes the tag 12 disposed in the diaper 10 and the antenna 16 located outside the diaper 10 for applying drive energy to the tag 12 and transmitting/receiving signals to/from the tag 12. The antenna 16 is composed of frame-shaped copper foil incorporated in a sheet 40 covering a care-receiver 34. By incorporating the antenna 16 in the sheet 40, smooth communication between the tag 12 and the antenna 16 can be achieved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid detection device that detects liquid such as urine and blood from the communication status between an RFID tag and an antenna.

  Diapers are used for the care of bedridden caregivers, and in situations where the caregiver is unable to communicate his urine to the caregiver due to reasons such as not being able to pronounce words well, Changing diapers. However, if the cared person is incontinent for a long time, the urine odor may be filled or diaper rash may occur.

  Also, caregivers can not grasp the internal situation without opening the diaper, so it often happens that caregivers who have not been incontinence have to open and reapply diapers, and unnecessary labor is required. In addition to being generated, there is a problem in that the care receiver is disturbed. Therefore, an incontinence sensor that can sense incontinence without the caregiver opening the diaper has been developed.

  As this incontinence sensor, a method using an electrode, a moisture sensor, a camera, and a thermoelectric element has been proposed. However, these methods are large and the caregiver feels uncomfortable at the time of wearing, the caregiver needs to go to the caregiver to check for incontinence, or the diaper has a wiring out. It looked bad.

  Furthermore, as an incontinence sensor, there is also a device that detects incontinence wirelessly by mounting a disposable transmitter inside the diaper and including a receiver outside the diaper. However, this type of apparatus has problems such as a feeling of wearing the transmitter and troublesome battery replacement. Furthermore, there has been a problem that the wiring constituting the transmitter is disconnected due to a bending operation associated with use of the diaper.

  Further, referring to the following Patent Document 1, a diaper wetness notification display device using a passive RFID tag is disclosed. Referring to FIG. 1 and the like of the patent document, urine is detected by a wetness detection sensor provided inside the diaper, and data such as detected urine is transmitted from the RF-ID tag to the display device. The display device displays the number of incontinences or the time since incontinence based on the input data.

JP-A-2005-602

  However, the above-described Patent Document 1 does not disclose anything regarding the installation location of the antenna that communicates with the RFID tag.

  If the distance between the RFID tag and the antenna is too long, the two cannot communicate with each other, and the presence and amount of liquid such as urine cannot be estimated from the communication status of both. On the other hand, in order to make the distance between the RFID tag and the antenna closer, for example, a method of attaching the RFID tag inside the diaper and sticking the antenna outside the diaper is conceivable. However, if it does so, both the RFID tag and the antenna will be discarded along with the replacement of the diaper, and the cost will become very high by providing the urine detection device.

  The present invention has been made in view of the above-described problems, and a main object of the present invention is to provide a liquid detection device capable of reliably performing communication between a tag mounted inside a diaper and an antenna. It is in.

  The liquid detection device of the present invention is a passive type RFID tag attached to a diaper worn by a user, and is located outside the diaper to give driving energy to the RFID tag and to exchange signals with the RFID tag. A reader antenna; and a control device that detects moisture present in the diaper based on a change in communication status between the RFID tag and the reader antenna, and the reader antenna is used in a lying state It is incorporated in the main surface or inside of the floor cloth to be hung on a person.

  According to the present invention, since the antenna that communicates with the RFID tag is incorporated in the floor cloth that is hung on the user lying on the side, the distance between the RFID tag and the antenna becomes appropriate, and both can communicate well. It becomes.

  Furthermore, even when the diaper is replaced by urine discharged by the user, only the relatively inexpensive RFID tag is discarded together with the diaper. On the other hand, the antenna is not discarded together with the diaper and can be used continuously for a long period of time as a floor covering, so that an increase in cost due to the introduction of the detection device is suppressed.

  Furthermore, when the user is lying on the spring bed, if the antenna and the spring bed are too close to each other, the antenna and the RFID tag cannot communicate with each other due to the demagnetizing field generated from the spring built in the spring bed. . In the present invention, since the antenna and the spring bed are separated by the user's torso by arranging the antenna on the flooring, communication is not hindered by the demagnetizing field generated from the spring bed.

  Even if the user lies down or turns over, the antenna is hung on the user with a floor covering, so that communication is hardly hindered.

It is a figure which shows the urine detection apparatus which is an example of the liquid detection apparatus of this invention, (A) is a top view which shows a liquid detection apparatus and its use condition, (B) is sectional drawing, (C) is It is a top view which shows the structure of an antenna. It is a figure which shows the urine detection apparatus which is an example of the liquid detection apparatus of this invention, (A) is a figure which shows the structure of a liquid detection apparatus, (B) is a perspective view which shows the structure of a tag. It is the schematic which shows the urine detection apparatus which is an example of the liquid detection apparatus of this invention. It is a flowchart which shows the method of detecting urine with the urine detection apparatus which is an example of the liquid detection apparatus of this invention. It is a figure which shows the method of measuring urine volume with the urine detection apparatus which is an example of the liquid detection apparatus of this invention, (A)-(C) is sectional drawing. The result performed in order to measure the amount of urine with the urine detection apparatus which is an example of the liquid detection apparatus of this invention is shown, (A) and (B) are graphs. It is a table | surface which shows the result performed in order to measure urine volume with the urine detection apparatus which is an example of the liquid detection apparatus of this invention. The result performed in order to measure urine volume with the urine detection apparatus which is an example of the liquid detection apparatus of this invention is shown, (A)-(C) is a table | surface. The result performed in order to measure the amount of urine with the urine detection apparatus which is an example of the liquid detection apparatus of this invention is shown, (A) and (B) are graphs. The result performed in order to measure the amount of urine with the urine detection apparatus which is an example of the liquid detection apparatus of this invention is shown, (A) and (B) are graphs. It is a graph which shows the result performed in order to measure urine volume with the urine detection device which is an example of the liquid detection device of the present invention. The result performed in order to measure the amount of urine with the urine detection apparatus which is an example of the liquid detection apparatus of this invention is shown, (A) and (B) are graphs. The result performed in order to measure the amount of urine with the urine detection apparatus which is an example of the liquid detection apparatus of this invention is shown, (A) and (B) are graphs. The result performed in order to measure the amount of urine with the urine detection apparatus which is an example of the liquid detection apparatus of this invention is shown, (A) and (B) are graphs. (A) And (B) is a figure for demonstrating the surface tension which acts on urine. It is sectional drawing which shows the urine detection tag which is an example of the liquid detection apparatus of invention. It is a figure which shows the urine detection tag which is an example of the liquid detection apparatus of invention, (A) thru | or (D) are sectional drawings of the projection part with which a tag is equipped. It is a perspective view which shows the projection part with which the urine detection tag which is an example of the liquid detection apparatus of invention is equipped. It is sectional drawing which shows the through-hole with which the urine detection tag which is an example of the liquid detection apparatus of invention is equipped. (A) And (B) is a graph which shows the experimental result using the urine detection tag which is an example of the liquid detection apparatus of invention.

  Details of the liquid detection device of the present invention will be described below. In the following description, urine excreted by the user is exemplified as an example of the liquid to be detected. However, liquids other than urine can be adopted as the liquid to be detected. Specifically, the blood or sweat of the user (caregiver) can be detected by the detection device of this embodiment. By detecting the user's blood with the detection device of the present embodiment, blood that has flowed to the outside due to a medical action such as blood transfusion or surgery can be detected. Moreover, it is possible to prevent wrinkles by detecting sweat generated from the user by the detection device of the present embodiment. Here, the detection includes, for example, determining whether or not a certain amount or more of urine is present inside the diaper, and estimating the amount of urine discharged inside the diaper.

<First Embodiment>
In this embodiment, the configuration of the urine detection device of this embodiment and a urine detection method using the same will be described with reference to FIGS.

  The configuration of the urine detection device 11 will be described with reference to FIG. FIG. 1A is a diagram showing a state in which the urine detection device 11 is used for a care recipient (user), and FIG. 1B is a cross-sectional view of the state of FIG. FIG. 1C is a plan view showing the configuration of the antenna 16 in detail.

  Referring to FIG. 1A, a urine detection device 11 according to the present embodiment includes a tag 12 provided in a diaper 10 and a laying cloth 40 that provides driving energy to the tag 12 and outputs a signal to the tag 12. It has a configuration mainly including an antenna 16 for transmitting and receiving.

  In the urine detection device 11 of the present embodiment, the tag 12 and the reader 14 (antenna 16) communicate with each other at regular intervals, and the cared person 34 who uses the diaper 10 by changing the state of communication. Detecting incontinence. That is, if the communication between the tag 12 and the reader 14 (antenna 16) can be normally performed, it is determined that the cared person using the diaper 10 is not incontinent. On the other hand, if the communication between the tag 12 and the reader 14 is interrupted for a certain time or more, it is determined that the urine has contacted the tag 12 (that is, the care recipient has been incontinent). In addition, as will be described later, it is possible to estimate the amount of urine discharged by the care recipient from the time required for recommencement of communication.

  The tag 12 is provided in a diaper 10 typified by a paper diaper. The tag 12 may be attached to the inner surface of the diaper 10 or may be built in the diaper 10 itself. In the present embodiment, the tag 12 is of a passive type, performs processing that requires an IC using drive energy supplied from the reader 14, and transmits the data generated by this processing to the reader 14 on a carrier wave. It has a function. This type of tag is referred to as an RFID (Radio Frequency Identification) tag, a wireless IC, an IC tag, an RF tag, or the like. Here, only one tag 12 is shown, but a plurality of tags 12 may be arranged inside the diaper 10 by utilizing the anti-collision function of the reader 14.

  The antenna 16 has a function of generating an electromagnetic wave for driving the tag 12 and receiving a radio wave transmitted from the tag 12. The reader 14 is electrically connected to the antenna 16 by wire, and an electromagnetic wave including control information is transmitted from the antenna 16 of the reader 14 to the tag 12.

  There are an electromagnetic induction method and a radio wave method for the passive tag 12 to obtain electric power. In the electromagnetic induction method, since electric power is generated by a magnetic field, radio waves are not used, and communication is relatively possible even when moisture is nearby. On the other hand, the radio wave method is a method of converting radio wave energy into electric power, and the communication distance is longer than that of the electromagnetic induction method (5 to 6 m in the case of the UHF band). Radio waves are absorbed and communication becomes impossible. Therefore, in this embodiment, since the urine which is moisture is handled, the electromagnetic induction method is more suitable as a method for the tag 12 to obtain electric power. In the present embodiment, the RFID tag 13 is used in the 13.56 MHz band.

  With reference to FIG. 1 (A), in this embodiment, the antenna 16 is incorporated in a mat 40 that is hung on the care receiver 34 in a lying state. The bedding 40 may be a dedicated cloth for installing the antenna 16, or the antenna 16 may be incorporated in a normally used blanket or futon. Furthermore, as a method for incorporating the antenna 16, the antenna 16 may be woven together with the fibers of the mattress 40, incorporated in the mattress 40, or the antenna 16 may be attached to the upper surface or the lower surface of the mattress 40.

  With reference to FIG. 1 (B), the urine detection device 11 of this embodiment is used for a cared person 34 lying on the upper surface of a spring bed 42. A bedding 40 is hung on the cared person 34, and the antenna 16 is incorporated in the bedding 40.

  Here, a large number of springs 44 made of metal are built in the spring bed 42. Therefore, when a magnetic field is generated from the antenna 16 to give drive energy to the tag 12, a phenomenon occurs in which the magnetic field generated from the antenna 16 is canceled by the demagnetizing field generated from the spring 44 that is a metal. If the distance between the antenna 16 and the spring 44 becomes shorter than a certain value, the cancellation phenomenon causes the tag 12 and the antenna 16 disposed between them to be unable to communicate with each other.

In this embodiment, the antenna 16 is separated from the upper surface of the spring bed 42 by a certain distance or more in order to avoid a phenomenon in which communication is not possible due to the demagnetizing field. For example, it has been found that the cancellation phenomenon described above can be alleviated by setting the distance L3 between the upper surface of the spring bed 42 and the antenna 16 to 20 cm or more.
Here, a case where a metal member such as a spring is not used for the spring bed 42 and diamagnetism does not need to be considered is considered. In the case where the floor covering 40 having the antenna 16 is laid on the lower portion of the cared person 34 and on the upper portion, the communication can be stabilized by hanging on the upper portion. This is because when the cared person 34 moves, the floor cloth 40 laid on the lower part is deformed and the antenna is also deformed, and stable communication cannot be performed. Stable communication is possible without deformation.

In particular, when the cared person 34 turns sideways, the spring bed 42 is greatly deformed, and communication is not stable with the bedcloth 40 laid down below. Moreover, the direction hung on the upper part does not apply a force to the mattress 40 and can be used for a long time. With regard to the positional deviation, even when the positional deviation is found in the communication situation, it is easier to correct the positional deviation by placing the top 40 on the floor. If communication is not possible due to misalignment, a nurse, attendant, etc. may reapply the overlaid cloth 40, but if the underlaid cloth 40 is laid down, it is necessary to move the cared person 34. is there.
In addition, if it is laid on the lower part, local damage may enter the antenna and stable communication cannot be performed, or there is a high possibility of breakage, and the cloth 40 may get wet with urine, water, etc., and communication may not be possible. .

  Furthermore, if it is hung on the upper part, the bedding 40 bends along the body of the cared person 34, and the distance between the antenna 16 and the tag 12 becomes constant as a whole. The distance between the antenna 16 and the tag 12 is greatly different between the end and the center, and communication is easily affected by a slight change in position.

  Here, the antenna 16 is separated from the spring 44 by a predetermined amount or more depending on the body thickness of the cared person 34. Specifically, the antenna 16 is separated from the upper surface of the spring bed 42 by hanging the mat 40 on the cared person 34 so that the antenna 16 is disposed on the upper surface of the cared person 34. That is, the antenna 16 does not contact the upper surface of the spring bed 42, and as a result, cancellation due to the demagnetizing field is suppressed.

  Furthermore, in this embodiment, the communication range in the direction penetrating the antenna 16 (the range in which the magnetic field generated from the antenna 16 extends in the vertical direction on the paper surface) is longer than the thickness (L3) of the conductor of the care recipient 34. Is set. By doing so, even if the antenna 16 is arranged away from the spring bed 42, the antenna 12 can communicate with the tag 12 built in the diaper 10 worn by the care recipient 34.

  A more specific configuration of the antenna 16 will be described with reference to FIG. The antenna 16 is composed of an elongated conductive foil (for example, a copper foil) arranged in a frame shape. Here, when the length of the antenna 16 in the lateral direction with respect to the cared person 34 is L1, and the length of the antenna 16 in the vertical direction with respect to the cared person 34 is L2, the length of L1 is, for example, 25 cm or more. It was 35 cm or less (30 cm as an example), and the length of L2 was, for example, 50 cm or more and 60 cm or less (55 cm as an example).

  By setting the lateral width L1 of the antenna 16 to 25 cm or more and 35 cm or less, the width L1 becomes shorter than the width of the general body of the cared person 34. Therefore, referring to FIG. 1 (B), when the bedcloth 40 incorporating the antenna 16 is hung on the cared person 34, the antenna 16 is disposed above the trunk of the cared person 34. Therefore, the body of the cared person 34 allows the antenna 16 to be separated from the spring bed 42 by a predetermined amount or more, and the above-described trouble caused by the demagnetizing field generated from the spring 44 is avoided.

  Here, the reader 14 and the antenna 16 are electrically connected via the connection line 46 and the connection line 48. Further, the place where the connection line 46 is connected to the antenna 16 and the place where the connection line 48 is connected to the antenna 16 are arranged to be symmetrical.

  The details of the urine detection device 11 will be described with reference to the tag 12 with reference to FIG. 2A is a diagram showing the mechanism of the urine detection device 11, and FIG. 2B is a perspective view showing the configuration of the tag 12 in detail.

  Referring to FIG. 2A, the diaper 10 worn by the care recipient 34 has a built-in tag 12, and an antenna 16 and a reader 14 that communicate with the tag 12 are disposed outside the diaper 10. . As described above, the antenna 16 has a function of driving the tag 12 by generating an electromagnetic wave (magnetic field) with respect to the tag 12 and receiving data generated from the tag 12.

Further, the reader 14 includes a communication control unit 18 and a calculation unit 20. The computing unit 20 is composed of a memory for recording information and a logic circuit for performing reading / writing, computation, authentication, encryption, and the like of the memory. The communication control unit 18 is a part that controls communication with the tag 12 via the antenna 16.

  Next, a mechanism for detecting urine by the urine detection device 11 will be described with reference to FIGS. 2 (A) and 2 (B).

  First, an electromagnetic wave (magnetic field) having a strength of about 1.5 A / m to 7.5 A / m is generated from the antenna 16 of the reader 14. By the action of electromagnetic induction by this magnetic field, an AC voltage of 13.56 MHz, for example, is generated in the coiled antenna 22 of the tag 12. Then, the AC voltage generated is converted into a DC voltage by a rectifier circuit built in the IC chip 24. Here, in order to drive the IC chip 24, generally a voltage of 3V, a low voltage of 1.8V is required.

  The tag 12 that has secured the power supply by electromagnetic induction communicates with the reader 14 by performing load modulation that controls the amount of the radio wave received by the antenna 22 that is reflected and emitted again. As load modulation, there are amplitude modulation (ASK) for changing the amplitude, frequency modulation (FSK) for changing the frequency, and phase modulation (PSK) for changing the phase, and any of them can be adopted in this embodiment.

  In the present embodiment, electromagnetic waves are generated from the antenna 16 of the reader 14 at regular intervals, and when the reader 14 and the tag 12 are communicating, urine is not attached to the tag 12 (that is, the cared person is I have not incontinence).

  On the other hand, if the cared person is incontinent and urine adheres to the tag 12, communication between the tag 12 and the reader 14 becomes impossible. The reason why communication cannot be performed in this manner is that when urine containing electrolyte adheres to the tag 12, current passes through the electrolyte, the capacitance of the tag 12 such as the antenna inductance and capacitance changes, and the resonance frequency fluctuates. Therefore, it can be considered that the Q value decreases and does not resonate, and as a result, the electromotive force of the antenna 22 does not reach the driving voltage of the IC.

  Here, the phenomenon in which communication cannot be performed occurs when urine is in direct contact with the antenna 22 of the tag 12. Furthermore, even when the antenna 22 is covered with a resin layer, communication cannot be performed if urine adheres to the resin layer.

  According to experiments, when saline is dropped on the upper surface of the RFID tag 13, the voltage generated by the tag drops to about 2.5V in the case of one drop, and this voltage becomes 2.1V or less when two or more drops are dropped. Communication is interrupted. Therefore, according to the present embodiment, a very small amount of urine leakage can be detected by the tag 12.

  Furthermore, when tap water that does not contain salt or the like is dropped on the RFID tag, it has been experimentally found that the voltage generated by the tag does not decrease so much and communication is not interrupted. Therefore, even if moisture generated by the steaming inside the diaper 10 adheres to the tag 12, the communication of the tag 12 will not be interrupted. However, since the above-described communication is hindered when the diaper 10 is dampened by sweat, the tag 12 of this embodiment can be used as a device for detecting sweat.

  The configuration of the tag 12 will be described in detail with reference to FIG. The tag 12 has a configuration in which the RFID tag 13 and the drainage sheet 28 are superimposed, and a space for discharging urine is secured below the RFID tag 13.

  In this embodiment, an RFID tag of RI-I02-112B manufactured by Texas Instruments is used as the RFID tag 13. In this tag, an antenna 22 having a thin conductive foil spirally and an IC chip 24 are arranged on the upper surface of a substrate made of PET (Polyethylene terephthalate) having a thickness of about 0.05 mm. Therefore, this tag is very flexible and the minimum bending radius is about 18 mm. The unit price per tag is currently 100 yen, and it is a price that cannot be easily disposed of. However, since it is mass-produced when used as a substitute for the barcode, which is a conventional article management method, Is likely to be cheaper and easier to disposable. Further, since RI-I02-112B conforms to the standard of ISO15693, the magnetic field strength required for communication is 1.5 to 7.5 A / m.

  The upper surface and the lower surface of the RFID tag 13 may be covered with an insulating resin such as silicon resin. By doing in this way, adhesion of urine to the IC chip 24 is prevented.

  Further, an opening 26 is provided by cutting out the vicinity of the center of the RFID tag 13 into a square shape. This opening 26 is for allowing the urine to pass therethrough to improve the drainage.

  The drainage sheet 28 is formed by integrally molding a silicon resin into a predetermined shape, and has a shape in which the protruding portion 31 protrudes upward from the upper surface of the thin plate-like substrate 30. Here, referring to FIG. 2B, the upper end of the protrusion 31 contacts the lower surface of the RFID tag 13, so that the space corresponding to the height of the protrusion 31 is the lower surface of the substrate 15 of the RFID tag 13. And the upper surface of the base material 30 of the drainage sheet 28 are secured.

  A plurality of protrusions 31 are arranged on the upper surface of the base material 30 at equal intervals, and the distance at which the protrusions 31 are separated from each other is about 4.66 mm. The height of the protrusion 31 is about 1.66 mm, and the width is about 1.0 mm. In the figure, the protrusion 31 has a conical shape, but other shapes can also be adopted, and may be a pyramid shape, a columnar shape, a prismatic shape, or the like.

  The through holes 32 are provided so as to partially penetrate the base material 30, and a plurality of through holes 32 are arranged at equal intervals on the base material 30. The diameter of the through hole 32 is, for example, about 1.0 mm. The urine adhering to the RFID tag 13 is discharged to the outside (diaper) through the through hole 32 and absorbed.

  It is also possible to use artificial turf as the drainage sheet 28 described above. The reason is that artificial turf is excellent in drainage, flexibility and cost. Furthermore, an adhesive layer made of an adhesive for attaching the tag 12 to the diaper 10 may be provided on the back surface of the drainage sheet 28.

  According to the tag 12 configured as described above, after urine adheres to the RFID tag 13, the urine is released to the outside of the tag 12 through the space between the RFID tag 13 and the drainage sheet 28. Therefore, even if the urine adheres to the tag 12 and the communication between the tag 12 and the reader 14 is interrupted, the urine attached to the tag 12 is quickly released to the outside. Therefore, the communication between the tag 12 and the reader 14 takes several tens of seconds. Recovered at a degree. After that, when urine again adheres to the tag 12 and communication with the reader 14 is interrupted, incontinence can be detected again. From this, it becomes possible to detect the care recipient's multiple incontinence by one tag 12.

  Furthermore, the tag 12 having the above-described structure is flexibly deformed even when stress is applied due to the cared person's body moving under use conditions, and thus the problem that the antenna 22 is disconnected due to this stress is alleviated.

  In the above description, the tag 12 is configured from the stacked RFID tag 13 and drainage sheet 28, but it is also possible to use only the RFID tag 13 as the tag 12 without using the drainage sheet 28. By doing in this way, tag 12 itself becomes cheap and the increase in cost by introduce | transducing a urine detection apparatus can be suppressed.

  Next, the configuration of the urine detection system including the urine detection device 11 described above will be described with reference to FIG. Referring to this figure, similarly to the above, the tag 12 is provided in a diaper used by the care recipient 34. The antenna 16 of the reader 14 is formed in a loop shape on a mat that is hung on the care recipient 34. When the care recipient 34 is incontinent, communication between the tag 12 and the reader 14 is interrupted for a predetermined time or more, and the incontinence information is recorded in the computer 36 (control device) as a server. Examples of the incontinence information include “when was incontinence”, “what is the number of times of incontinence”, “what is the total number of incontinence”, “how much is urine volume”, and the like. And by acquiring and storing this incontinence information over time, it becomes easier for the caregiver or doctor to grasp the life rhythm of the cared person, and care and treatment suitable for the state of each cared person becomes possible. .

  After the incontinence information is recorded on the computer 36, the incontinence information is notified to a PDA (Personal Digital Assistants) terminal owned by the caregiver 38, and the caregiver 38 changes the diaper of the care recipient 34. As a result, the caregiver 38 can confirm the presence or absence of incontinence without opening the diaper, so that care is efficiently performed. Further, since the tag 12 is inexpensive and can be disposable, the diaper provided with the tag 12 can be used in the same manner as a normal one.

  Based on the flowchart of FIG. 4, a method for detecting urine by the urine detection device 11 will be described with reference to FIG. 1.

  First, the system is activated (step S11), and a loop for detecting urine is started (step S12). Here, Timer is set to 1 second, and the tag 12 is read by the reader 14 at this interval. Further, when the reader 14 is operated by a PC (personal computer), a driver for recognizing the USB port attached to the reader 14 as an RS232C port is installed in the PC.

  Next, it is determined whether or not the tag 12 exists in the communication range of the reader 14 (step S13). In other words, it is determined whether or not the reader 14 and the tag 12 can communicate. If the tag 12 exists, the process proceeds to step S14. If the tag 12 does not exist (if communication is not possible), the process proceeds to step S18.

  In step S14, data is read from the IC chip 24 of the tag 12 and stored in the program. Individual data indicating the name of the care recipient is written in the IC chip 24 of the tag 12, and this data is read out.

  In step S15, the data read in the previous step is compared with the data that has already been read and stored in the memory to determine whether they are the same. If the data is the same, it is determined that communication is made with the same tag (YES in step S15), and the variable Count is set to zero. Then, the process returns to step S12 via step S17.

  On the other hand, if the read data does not match the data in the memory, the process proceeds to step S18 (NO in step S15).

  In step S18, it is confirmed whether there is data in the memory. If there is data (YES in step S18), the variable Count is incremented by one (step S19). On the other hand, if there is no data in the memory (NO in step S18), the process proceeds to step S22.

  In step S20, it is determined whether or not the variable Count is 10 or more. If the variable Count is 10 or more, it is determined that incontinence has been detected since communication with the tag has been interrupted for 10 seconds or more (step S21). If the variable Count is less than 10, the process returns to step S12 via step S22.

  In step S21, the time when incontinence is detected is read from the computer and recorded as the incontinence time. Furthermore, the information is notified to the terminal or personal computer to which the IP address designated in advance is assigned. Then, if necessary, the caregiver is notified of incontinence. By acquiring these data over a long period of time, it becomes possible to statistically understand the times when caregivers are prone to incontinence, and it is possible to obtain diaper changes and vital signs for individual caregivers. Appropriate care can be provided for each.

  Furthermore, since the tag 12 used in the present embodiment is configured to include the drainage sheet 28, the detected urine is quickly separated from the tag 12. Therefore, even if the communication between the tag 12 and the reader 14 is interrupted for a certain time due to the urine adhering to the tag 12, the urine adhering to the tag 12 is drained well and absorbed by the diaper 10, and the tag 12 and the reader 14 Communication with is restored. If the urine adhering to the tag 12 is not drained well, it is possible to detect one incontinence by one tag 12, but the communication between the tag 12 and the reader 14 is not recovered, so a plurality of incontinences are detected. It is not possible. On the other hand, in this embodiment, since the urine is drained to the outside of the tag 12 by the drainage sheet 28 attached to the lower surface of the RFID tag 13, the communication between the tag 12 and the reader 14 is recovered and a plurality of times. Incontinence can be detected.

  The above is the description of the method for detecting the presence or absence of urine, but the above-described detection method can also be used for detecting the amount of urine. In this case, after the above-described step S20, a step of measuring the time until communication is restored and calculating the urine volume from the measured time is required. A specific method for specifying the urine volume will be described in a second embodiment described later.

  Here, in the above description, the RFID tag 13 and the drainage sheet 28 are overlapped and used as the tag 12. However, the drainage sheet 28 may be omitted and only the RFID tag 13 may be mounted inside the diaper. .

<Second Embodiment>
In this embodiment, a method for measuring urine volume using the urine detection device having the above-described structure will be described with reference to FIGS.

  In this embodiment, the matter for measuring the amount of urine discharged by the user into the diaper using the urine detection device 11 (see FIG. 1) used in the first embodiment will be described. Specifically, referring to FIG. 2 (B), the tag 12 incorporated in the diaper includes a drainage sheet 28 for discharging urine in contact with the tag. Even if the update is interrupted, the communication is restored after a certain period of time. Further, it is predicted that the time required for the return has a correlation with the urine discharged by the user into the diaper. For this reason, in this embodiment, the amount of urination is detected by measuring the time until the communication between the reader (antenna) and the RF tag 12 is restored.

First, the relationship between the urine discharged by the user and the drainage sheet will be described with reference to FIG. From Bernoulli's theorem, the drainage time T is obtained by Equation 1 when the area A of the RF tag 13, the height H of the RF tag 13 and drainage sheet 28, the number of through holes n, and the flow rate Q of one through hole are obtained. be able to. Here, T is the time required for the RFID tag 13 to return after the communication is interrupted.
Formula 1: T = (A × H) / (n × Q)
Here, if the amount of water L = A × H,
Formula 2: L = (n × Q) × T
It becomes. Further, Q is a flow coefficient c of water, an area a of the through hole, and a weight acceleration g.
Formula 3: Q = ca (2 gH) ^1/2
It can be expressed.

  From these equations, the optimum shape of the drainage sheet 28 is designed. The drainage sheet 28 is composed of a plate-like base material 30, a protrusion 31 protruding in a conical shape from the upper surface of the base material 30, and a through-hole 32 provided through the base material 30. . Further, as the material of the drainage sheet 28, a resin material such as silicone resin is employed. In addition, about the suitable shape of the waste_water | drain sheet | seat 28, it demonstrates in 3rd Embodiment mentioned later.

  The principle of measuring urine volume using the RFID tag 13 will be described with reference to each drawing of FIG.

  As shown in FIG. 5A, the tag 12 composed of the RFID tag 13 and the drainage sheet 28 is stuck inside the diaper 10. In an initial stage where urine is not attached to the tag 12, the RFID tag 13 can communicate with an antenna disposed outside the diaper 10.

  Next, referring to FIG. 5B, when the urine 52 is discharged from the user, the urine 52 is interposed between the RFID tag 13 and the drainage sheet 28. When this happens, the communication between the RFID tag 13 and the antenna (reader) is temporarily interrupted due to the salt contained in the urine 52.

  Referring to FIG. 5C, urine 52 located between RFID tag 13 and drainage sheet 28 moves to and is absorbed by diaper 10 via through hole 32 provided in drainage sheet 28. The In this case, the influence of the urine 52 on the RFID tag 13 is reduced, so that the communication between the RFID tag 13 and the antenna is resumed.

  In this embodiment, as described above, the time from when communication is stopped until it returns is measured, and the amount of urine discharged by the user is estimated from the time required for this return.

  Using the tag 12 described above, a principle confirmation experiment using saline was performed. The saline used in the experiment has the same salt concentration as urine, approximately 0.6%. The amount of human urination is 50 cc to 300 cc. Therefore, 50 cc to 300 cc of saline is dropped and the recommunication time is measured. As an experimental method, 50 cc of salt solution to be dropped is added, and the drainage time is measured. Similarly, 100 cc, 150 cc, 200 cc, 250 cc, and 300 cc were added. In addition, the re-communication time of the drainage mechanism with and without diapers was measured.

  FIG. 6A shows the measurement result of the re-communication time using the urine output measuring system. The horizontal axis shows the re-communication time (the time from communication interruption due to urine recovery), and the vertical axis shows the amount of accumulated saline. In the case of 50 ml, when saline is accumulated in one diaper and a certain amount of each aqueous solution is added, it can be confirmed that the amount of the aqueous solution increases and the drainage time becomes longer. Since the amount of drainage per unit time is constant, it is considered that when salt solution is added in a certain amount, the absorbent capacity of the diaper decreases and the recommunication time is delayed.

As described above, the flow rate is ca (2 gH) ^1/2 . That is, it can be derived that the liquid flows out at the same speed as when the height of H is dropped freely.

  However, commercially available diapers do not absorb liquid instantaneously, and it takes several seconds to complete absorption. Therefore, when the drainage mechanism is built in the diaper, a time lag is considered to occur until the liquid is absorbed by the diaper even if it is assumed that the drainage mechanism has passed through at the same speed as free fall. Accordingly, the drainage time was measured using two types of patterns: a combination of the RFID tag 13 and the drainage sheet 28 (A) and a combination of the RFID tag 13 and the drainage sheet 28 in the diaper (B).

  FIG. 6B shows the measurement results. The measurement results of (A) are plotted with black triangles, and the measurement results of (B) are plotted with black squares. The measured value of (A) is close to the theoretical value. On the other hand, when the drainage mechanism was built in the diaper, the speed equivalent to free fall could not be obtained. That is, it has been clarified that the time required for the communication to return is longer when the tag 12 is incorporated in the diaper than when the tag 12 is left as it is.

  Next, an experiment by the subject was conducted separately from the principle confirmation experiment. Since it is intended for bedridden elderly people, it is necessary to conduct an experiment in a supine position. In an actual elderly care facility, a urine pad was wrapped around the penis and a diaper was worn on top of it, so the experiment was conducted in the same way. After urination, the amount of urine absorbed by the diaper was taken as the actual measurement value, and the test was conducted with four general adult men aged 22-24. The experimental results are shown in FIG.

Next, the relationship between the diaper absorption rate and the drainage rate will be described. The drainage speed when the drainage sheet and the RFID tag are built in the diaper must consider the influence of diaper absorption. The slope of the theoretical value and the measured value can be obtained by the following formula.
Formula 4: k = (measured drainage speed) / (theoretical drainage speed)
= 8.056 / 25.86
= 0.31
This inclination k is defined as a diaper absorption coefficient. From this k, the relationship between the amount of drainage of diapers and the drainage time can be determined.

Calculated renegotiation time urine volume measurement system, time T _D by the diaper absorption, when the T _R the theoretical value,
Formula 5: T _D = kT _R
It is.

  Next, 4 subjects were asked for cooperation, and the amount of urination and the time until re-communication were measured using a urine volume measurement system. The measurement results are summarized in the table of each figure of FIG. 8, and are summarized in the graphs of FIGS.

  From the graph of the measurement result, it can be seen that there is a tendency similar to the calculated value and the actually measured value. The cause of the error is thought to be due to the radio wave communication situation and the pressure on the diaper. The relationship between the pressure applied to the diaper and the drainage speed will be described later.

  Next, the relationship between the pressure time and the drainage speed will be described. An experiment was conducted on how the drainage rate is affected when pressure is applied to a diaper with a drainage sheet. The drainage time was measured by changing the force applied to the diaper to 0 g, 100 g, 200 g, 300 g, 400 g, and 500 g. The amount of liquid dropped is 100 ml, 200 ml, 300 ml, and the area where pressure is applied is a drainage mechanism size of 80 mm × 50 mm.

  The measurement results are summarized in the graphs of FIGS. Here, FIG. 11 shows a case where the weight applied to the diaper is 0 g, FIG. 12A shows a case where the weight is 100 g, FIG. 12B shows a case where the weight is 200 g, and FIG. Is a case where the weight is 300 g, FIG. 13B is a case where the weight is 400 g, FIG. 14A is a case where the weight is 500 g, and FIG. 14B shows the slope of the pressure and drainage time. It is a graph which shows a relationship.

From these graphs, it can be seen that as the force is applied, the drainage time becomes longer, and the slope of the drainage time and the amount of drainage becomes gentler. From the measurement results, if the pressure is a variable x, the slope can be obtained from the following theoretical formula.
Formula 6: a = e ^−0.02X
When the value of a obtained by Equation 6 is applied to the theoretical equation of Equation 2,
Formula 7: L = a × (n × Q) × T
The amount of drainage can be obtained.

  Next, the evaluation of urination measurement will be described. The experiment for measuring the amount of urination was performed as described above, and the theoretical value of the amount of urination is Equation 2 described above.

Here, since the drainage time is longer than the effect of absorption by diapers, if the absorption coefficient is k,
Formula 8: L = k × (n × Q) × T
It becomes. From the above consideration, the drainage time increases due to the pressure, and the slope becomes gentler. Therefore, if the pressure is a variable, it is necessary to consider Equation 6.
Formula 9: L = a × k × (n × Q) × T
Thus, a theoretical formula was newly derived in consideration of the absorption of the diaper absorbent and the pressure applied to the RF tag. Thus, the amount of urination can be obtained by the above formula 9, and the amount of urination in the diaper can be measured more accurately.

<Third Embodiment>
In this embodiment, the shape of the drainage sheet 28 provided in the tag 12 shown in FIG. 2B will be described with reference to FIGS.

  First, the surface tension that should be considered in order to optimize the shape of the drainage sheet 28 shown in FIG. 2B will be described with reference to FIG. FIG. 15A is a diagram for explaining the capillary phenomenon, and FIG. 15B is a diagram for showing parameters related to the strength of the surface tension.

  Referring to FIG. 15A, as is known in the capillary phenomenon, when a straw-shaped glass tube having a small diameter is inserted into water, the water surface in the tube is sucked up with a force stronger than gravity. The rising height is h, and the diameter in the tube is 2π. The liquid level in the tube is a curved surface with a recessed center. This phenomenon is called meniscus, and the liquid level is raised by surface tension generated between the capillary and the liquid.

  Considering the contact of the tube around the liquid meniscus, the vertical upward component of the force is γcosθ per unit length, and the total force of 2πr in contact with the tube is 2πrγcosθ. is there. γ cos θ is the surface tension of the capillary and the liquid. γ is 72.75 dyn / cm at 20 ° C. in the case of water.

The contact angle θ will be described with reference to FIG. The contact angle θ _varies depending on the temperature T, the surface tension γ _{L of} the droplet, the surface tension γ _{S of} the solid, and the interfacial tension γ _SL between the liquid and the solid. If the forces acting on point C are balanced,
γ _SL −γ _S + γ _L cos θ = 0
Holds. This equation is called Young's equation, and if γs> γ _S + γ _L , the contact angle θ does not exist, and the liquid naturally spreads on the solid surface and wets completely. That is, the mass of the liquid picked up in FIG. 15A is πρhr ² when the density of the liquid is ρ. Because the force that lifts upward by gravity and surface tension acting on this balances,
Formula 10: 2πrγcos θ = πρhr ²
Is obtained. As described above, the liquid is surrounded by the solid, thereby generating more surface tension. In other words, there is a force to stay there. Using Equation 10, the gravity applied to the liquid and the surface tension are compared, and a suitable shape of the drainage sheet is obtained.

  In Equation 10, the term on the left side is the force due to surface tension. As shown in FIG. 15B, this force changes depending on the length of the contact line where the liquid contacts the solid surface and the contact angle θ. On the other hand, the term on the right side is a force generated by gravity applied to the liquid, and this force decreases as the volume of the liquid decreases.

  FIG. 16 shows a cross section of the RFID tag 13 and the drainage sheet 28 constituting the tag. Here, for the sake of simplicity, the shape of the protrusion 31 is a columnar shape. A to D surrounded by circles are places where urine remains due to the influence of surface tension, which may make it difficult to recover the communication of the RFID tag 13. Region A is where the protrusion 31 and the RFID tag 13 come into contact. Region B is a space between the protrusions 31. Region C is a space between the upper surface of the substrate 30 and the RFID tag 13. The region D is an internal space of the through hole 32 that penetrates the base material 30. Region E is the back surface of the RFID tag 13. At these locations, urine may remain due to surface tension, and if a large amount of urine remains, communication between the tag and the reader may not be recovered. Therefore, the drainage sheet 28 needs to have a shape in which the surface tension is reduced and urine does not easily remain.

  With reference to FIG. 17, the optimal shape of the above-mentioned area A will be examined. 17 (A) and 17 (B) are views showing a cylindrical protrusion 31, and FIGS. 17 (C) and 17 (D) are views showing a conical protrusion 31.

  Referring to FIG. 17A, the upper surface of the protrusion 31 is not in contact with the lower surface of the RFID tag 13, and there is a gap between them. Therefore, urine may remain in the gap between the back surface of the RFID tag 13 and the top surface of the protrusion 31. Further, when the distance between the back surface of the RFID tag 13 and the upper surface of the protrusion 31 is shortened, the volume of urea decreases, but the area where urine can be applied to the back surface of the RFID tag 13 does not change.

  In addition, as shown in FIG. 17B, when the upper surface of the protrusion 31 is brought into close contact with the lower surface of the RFID tag 13, urine can be prevented from entering between the two. However, urine remains along a contact line in which the periphery of the upper end of the protrusion 31 contacts the back surface of the RFID tag 13. In this case, the amount of residual urine is proportional to the length of the contact line.

  Therefore, in the case shown in FIG. 17A and FIG. 17B, urine stays in the place where the surface tension force becomes larger than the gravity. If this happens, there is a risk that communication of the RFID tag 13 will be hindered by the remaining urine.

  In order to solve this problem, it is effective to reduce the area where the urine touches the solid. That is, the amount of residual urine can be reduced by reducing the radius of the cylindrical protrusion 31. However, if the shape of the protrusion 31 is extremely thin, the protrusion 31 is easily deformed when a vertical stress is applied on the paper surface, and a space between the base material 30 and the RFID tag 13 cannot be secured. There is a fear. Further, when a large number of extremely thin columnar protrusions 31 are provided, the deformation of the protrusions 31 is prevented, but it is technically difficult to form the thin columnar protrusions 31.

  Therefore, in the present embodiment, the shape of the protruding portion 31 is preferably a conical shape or a pyramid shape in which the tip portion is sharply formed.

  Referring to FIG. 17C, the conical protrusion 31 and the back surface of the RFID tag 13 are not in contact with each other, and there is a gap between the two. However, since the area of the tip of the protrusion 31 is small, the amount of residual urine is reduced.

  Referring to FIG. 17D, considering the case where the tip of the protrusion 31 comes into contact with the back surface of the RFID tag 13, the contact line of the protrusion 31 becomes extremely short. Even in this case, the amount of urine remaining Less.

  Furthermore, by making the shape of the protrusion 31 conical or pyramidal, it is possible to increase the thickness of the protrusion 31 and increase the mechanical strength simply by changing the angle of the tip.

Next, the area B shown in FIG. 16 will be described with reference to FIG. FIG. 18 is a diagram for explaining the surface tension acting on urine located between the protrusions 31. Referring to this figure, it is assumed that urine is present between the protrusions 31 of the rectangular parallelepiped, the urine is lifted up to a height z, the distance that the protrusions 31 are separated from each other is x, and the width of the protrusion 31 Is y. Then, the surface tension is due to the contact line 2x between the RFID tag 13 and the urine and the contact line 2y between the urine and the protruding portion 31, and the total is (2x + 2y) γcos θ. On the other hand, the volume of urine is xyz, and the force acting upward by gravity and surface tension acting on urine is balanced,
Formula 11: Formula of (2x + 2y) γcos θ = xyzρg is established.

  Further, referring to Expression 11, the value of the height z is related only to the term on the right side, and the value on the left side is not related to z. This suggests that when the height z of the protrusion 31 is lowered, urine located between the protrusions 31 may not flow and remain.

  Further, when the distance x between the protrusions 31 is shortened, the left side of Equation 11 is 2xγcosθ + 2yγcosθ, so 2yγcosθ, which is the second term, continues to be a vertically upward component without change, whereas the right side is proportional to the decrease in x. Then decrease. For this reason, if the distance x between the protrusions 31 becomes extremely short, urine may remain at this location. In the present embodiment, the distance x at which the protrusions 31 are separated from each other is set to 4.66 mm as an example.

Next, the region D shown in FIG. 16 will be described with reference to FIG. With reference to this figure, the surface tension acting on the urine located above the through hole 32 is opposite to the direction of gravity. The gravity acting on the urine changes depending on the volume of the urine located above the through-hole 32. The volume is πρzr ² and the surface tension is 2πrγcos θ.

Accordingly, when 2πrγcos θ = πρzr ² , the urine located above the through hole 32 remains there, and the urine is not discharged from the through hole 32 to the outside. Thus, in order to release urine from the through hole 32, it is necessary to set the radius r of the through hole 32 and the height z of the projection 31 so that 2πrγcos θ <πρzr ² . For example, in the present embodiment, the radius r of the through hole 32 is 0.5 mm, and the height z of the protrusion 31 is 1.66 mm.

  Next, with respect to the region E shown in FIG. 16, the amount of urine that remains attached to this portion can be reduced by applying a water repellent process to the lower surface of the RFID tag 13. This water repellent processing may be to cover the lower surface of the RFID tag 13 with a resin film having excellent water repellency such as silicon resin.

  With reference to the graph of FIG. 20A, the result of measuring the time required for communication recovery using the tag 12 having the above-described configuration will be described. In this experiment, seven diapers were used in two healthy 23-24 year old adult men. In the experiment, a urine collection pad was wrapped around a penis, and incontinence was performed several times until the tag stopped communicating with one pad, and the time until communication was recovered was measured.

  The horizontal axis of this graph indicates the time required for recovery of communication of a tag whose communication has been interrupted due to urine, and the vertical axis indicates the recovery rate. As shown in the graph, even if communication between the tag and the reader is interrupted due to incontinence, communication is recovered at a rate of about 80% after 100 seconds. And after 130 seconds, communication is recovered at a rate of about 90%. Moreover, even when the drainage sheet was molded with silicon resin or when the artificial lawn was used as the drainage sheet, the tag communication could be recovered satisfactorily.

  The time required for communication recovery will be described with reference to the graph of FIG. In this graph, the horizontal axis indicates the number of times of communication recovery, and the vertical axis indicates the time required for communication recovery as a ratio to the first time. Here, the experiment was performed a plurality of times (six times). As is apparent from this graph, the recovery time tends to increase as the number of times of recovery increases.

  In addition, according to experiments, the average number of times that a tag whose communication has been interrupted due to urine recovers communication is about 2.9 times, and communication is recovered four times at the maximum. Therefore, according to the tag of the present embodiment, a plurality of incontinences can be reliably detected.

  In addition, although the above presupposed that it was integrated in the main surface or the inside of the bedcloth hung on the user in the state lying on the bed, it can be similarly applied even when the user is seated on a chair or a wheelchair. The mat is used by being hung on the knee of the user seated on a chair. The chair also has a problem of diamagnetism as described above. In addition, it is better to hang the chair on the user than to draw a mat on the seat of the chair. In addition, the following can be said similarly to the above. If the width of the reader antenna is narrower than the width of the user's torso, communication can be performed without being affected by the chair. It is effective that the reader antenna does not contact the chair. The communication range in the direction penetrating the reader antenna may be longer than the thickness of the user's body. The water in the diaper is preferably urine excreted by the user. In the control device, the presence / absence of urine in the diaper is determined based on the change in the communication status between the RFID and the reader antenna as described above. The control device can also calculate the amount of urine excreted by the user based on the time from when communication between the RFID and the reader antenna is interrupted until it returns.

DESCRIPTION OF SYMBOLS 10 Diaper 11 Urine detection apparatus 12 Tag 13 RFID tag 14 Reader 15 Board | substrate 16 Antenna 18 Communication control part 20 Operation part 22 Antenna 24 IC chip 26 Opening part 28 Drain sheet 30 Base material 32 Through-hole 34 Caregiver 36 Computer 38 Caregiver 40 mattress 42 spring bed 44 spring 46 connection line 48 connection line 52 urine

Claims (9)

A passive RFID tag attached to a diaper worn by the user;
A reader antenna that is located outside the diaper, provides drive energy to the RFID tag and exchanges signals with the RFID tag;
Based on a change in communication status between the RFID tag and the reader antenna, a control device that detects moisture present in the diaper, and
The liquid detection device according to claim 1, wherein the reader antenna is incorporated in a main surface or inside of a floor cloth to be hung on the user.   The liquid detection device according to claim 1, wherein the reader antenna is formed of an elongated conductive foil arranged in a frame shape. (Use limited)
The liquid detection device according to claim 1, wherein the floor covering is used by being hung on the user lying on a spring bed, or hung on the user sitting on a chair.   4. The liquid detection apparatus according to claim 1, wherein a width of the reader antenna is narrower than a width of the torso of the user. 5.   The liquid detection device according to claim 4, wherein the reader antenna is not in contact with the spring bed or the chair on which the user lies in a state where the mat is hung on the user.   The liquid detection device according to claim 5, wherein a communication range in a direction penetrating the reader antenna is longer than a thickness of the user's body.   The liquid detection apparatus according to claim 6, wherein the moisture in the diaper is urine excreted by the user.   8. The liquid detection device according to claim 7, wherein the control device determines whether or not urine is present in the diaper based on a change in communication status between the RFID and the reader antenna.   9. The liquid according to claim 8, wherein the control device calculates an amount of urine excreted by the user based on a time from when communication between the RFID and the reader antenna is interrupted until the communication is restored. Detection device.