JP2001016025A - Antenna for trnsponder, transponder, and transponder unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transponder which can easily detect leakage of liquid from a distant place, its antenna structure, and a transponder unit. SOLUTION: A transponder 10 is constituted by sandwiching a transponder element 11 and an antenna 12, formed spirally of a belt-like conductor whose width is set extremely larger than the thickness between insulating film 13 and 14. Consequently, when an object body of detection such as water and oil comes into contact, the object body of detection generates electrostatic capacity between the adjacent belt-like conductors constituting the antenna 12 and a resonance frequency and transmission frequency of the antenna shift higher or lowers from its ordinary frequencies; and a matching state between the antenna 12 and transponder element 11 is deteriorates, and an arrival distance of a radio wave radiated from the antenna becomes short, so that even when a question signal is sent to the transponder, an answer signal from the transponder can no longer be received.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transponder antenna and a transponder which can be used for detecting a liquid such as water or oil, and a transponder unit in which a plurality of transponders are integrated.

[0002]

2. Description of the Related Art Conventionally, various devices have been devised for detecting a leak or a leak location of a liquid. Such liquid leakage must be detected, for example, in a landfill site for waste and the like, and a liquid transfer hose for transferring heavy oil and the like between a port complex and a tanker at sea.

[0003] In a landfill site for waste, in order to prevent the liquid flowing out of the waste from penetrating into the ground, a sheet called a water-blocking sheet is laid, and the waste is landfilled. By laying a waterproof sheet in this way, it is possible to prevent acidic, alkaline, or harmful sewage that has been dissolved in rainwater and spilled out of wastewater from penetrating into the ground and entering the groundwater, and collecting wastewater downstream. It can be treated with water and discharged.

However, when the water-blocking sheet is crushed, sewage seeps into the ground, so it is necessary to detect the leakage of sewage and specify the crushing position.

[0005] As an example of a means for detecting such breakage of the impermeable sheet, a leak detection method disclosed in JP-A-9-189636 has been known. This means that insulated wires are arranged in a vertical and horizontal grid below the impermeable sheet, their intersections are connected by an electrical conductivity sensor consisting of a diode and two electrodes, and the vertical and horizontal of the grid are operated by electric signals. Thus, leakage of contaminated water from the impermeable sheet and its location are detected.

Further, in order to detect leakage before actual damage is caused, a method has been devised in which sheets are doubled and a buffer area is provided between these two sheets.

[0007] In some cases, heavy oil or the like leaks from the tanker to the sea, causing serious damage to the nearby seas. In order to prevent such accidents,
Detection of liquid leaks in liquid transfer hoses is very important.

[0008] For this reason, as a liquid transfer hose, similarly to the above, an auxiliary liquid is supplied to the outside of the main body pressure-resistant cord layer through a liquid storage buffer layer through which liquid leaking from the main body pressure-resistant code layer flows in and convects. A double carcass hose having a structure in which a pressure-resistant cord layer is arranged has also been developed. Thus, when the main pressure-resistant code layer is broken, the liquid leaked from the main pressure-resistant code layer is blocked by the auxiliary pressure-resistant code layer and retained in the liquid storage buffer layer.

Further, as described above, there is known a hose in which the appearance change of the hose when the main body pressure-resistant cord layer is broken and liquid flows into the liquid storage buffer layer can be easily visually observed. As disclosed in Japanese Patent Application Laid-Open No. 5-272678, this hose has an asymmetrical cord layer which can be twisted by the pressure of the liquid flowing into the liquid storage buffer layer in the auxiliary pressure-resistant cord layer, so that the appearance of the hose can be visually checked. By doing so, leakage can be detected.

[0010]

However, in the two prior arts described above, in the former case, the range to be detected is a large area, and it is very difficult to specify a leak location. Furthermore, it is very troublesome to stretch insulated wires.

In the latter case, even if the hose has an asymmetrical cord layer, the pumping of the liquid is stopped and no abnormal appearance such as twisting of the hose can be recognized in a state where there is no hydraulic pressure. Furthermore, at the initial stage of liquid leakage, that is, at the stage when a small amount of liquid leakage starts to occur, the appearance of the hose has not been changed, and it has been impossible to find any abnormality in the initial stage of liquid leakage.

In view of the above problems, an object of the present invention is to provide a transponder capable of easily detecting liquid leakage from a remote position, an antenna structure thereof, and a transponder unit.

[0013]

According to the present invention, in order to achieve the above object, according to the present invention, a transponder main body having a transmitting / receiving means for transmitting a response signal when receiving an interrogation signal by an electromagnetic wave of a predetermined frequency is provided. An antenna constituting a transponder together with the transponder body, comprising a substrate made of an insulating plate or film, and a band-shaped conductor formed on the substrate, wherein the band-shaped conductor has a width with respect to its thickness. While being set very large,
The present invention proposes a transponder antenna in which at least a part of the strip-shaped conductor is arranged close to another part with a gap of a predetermined distance or less.

According to the transponder antenna, when a detection target such as water or oil comes into contact, a capacitance is generated by the detection target between adjacent strip-shaped conductors constituting the antenna. The frequency shifts to a frequency higher or lower than the normal frequency. For this reason, the matching state between the antenna and the transponder body deteriorates, the reach of radio waves radiated from the antenna is shortened, and even if an interrogation signal is transmitted to the transponder, a response signal from the transponder can be received. Disappears.
Further, by adopting the above-described structure, the magnetic flux density generated around the antenna is reduced.
Can be set to a low value, for example, a value of about 10.

According to a second aspect of the present invention, there is provided the transponder antenna according to the first aspect, wherein the band-shaped conductor is formed in a spiral shape.

According to the transponder antenna, the band-shaped conductor is formed into a spiral shape so as to resonate with the transmission / reception frequency of the transponder main body.

According to a third aspect of the present invention, there is provided the transponder antenna according to the first or second aspect, wherein a film is attached to the substrate surface on which the strip conductor is formed so as to sandwich the strip conductor. suggest.

According to the transponder antenna, the film prevents the strip conductor from deteriorating.

According to a fourth aspect of the present invention, in the transponder antenna according to any one of the first to third aspects, at least a surface of the substrate on which the band-shaped conductor is formed is provided with a member through which a liquid easily penetrates. Proposed transponder antenna.

According to the transponder antenna, by providing a member through which the liquid to be detected easily penetrates, the liquid can be brought into contact with the antenna even when the amount of the liquid to be detected is very small. Can be easily detected.

According to a fifth aspect of the present invention, there is provided a transponder antenna according to the fourth aspect, wherein a nonwoven fabric is used as the member through which the liquid easily penetrates.

According to the transponder antenna, since the nonwoven fabric is used as the member through which the liquid to be detected easily penetrates, it can be easily obtained and the cost can be reduced.

According to a sixth aspect of the present invention, there is provided a transponder having a transmitting / receiving means for transmitting a response signal when receiving an interrogation signal by an electromagnetic wave of a predetermined frequency, and an antenna connected to the transmitting / receiving means. A transponder provided with the antenna according to any one of the first to fifth aspects is proposed.

According to the transponder, when an object to be detected, such as water or oil, comes into contact, a capacitance is generated by the object to be detected between adjacent strip-shaped conductors constituting an antenna.
The resonance frequency and the transmission frequency of the antenna are shifted to frequencies higher or lower than the normal frequency. For this reason, the matching state between the antenna and the transponder body deteriorates, the reach of radio waves radiated from the antenna is shortened, and even if an interrogation signal is transmitted to the transponder, a response signal from the transponder can be received. Disappears. This makes it possible to detect that the detection target has come into contact.

According to a seventh aspect of the present invention, there is provided a transponder unit comprising two or more transponders for transmitting and receiving a radio wave of a predetermined frequency and transmitting a response signal when receiving the radio wave of the frequency, A transponder unit includes a first transponder whose transmission characteristic changes upon contact with a liquid and a second transponder which transmits and receives radio waves even upon contact with the liquid.

According to the transponder unit, the first
When an object to be detected, such as water or oil, comes into contact with the transponder, the transmission characteristic changes, so that communication with the transponder cannot be performed even when the radio wave of the interrogation signal is radiated. This makes it possible to detect that the first transponder, which cannot receive the response signal, is in contact with the liquid. Further, since the second transponder can transmit and receive radio waves without changing its transmission characteristics even when it comes into contact with liquid, it transmits a response signal when it receives an interrogation signal and performs normal communication. Can be. With this, it is possible to specify the installation position of the transponder unit by communication with the second transponder, and to perform necessary communication by the second transponder even when communication with the first transponder cannot be performed. Can be.

According to an eighth aspect of the present invention, in the transponder unit according to the seventh aspect, the first transponder is a transponder unit for transmitting and receiving a radio wave having a frequency that attenuates a predetermined value or more when transmitted through a liquid. Suggest.

According to the transponder unit, since the frequency of the transmission / reception radio wave of the first transponder is attenuated by a predetermined value or more when transmitting through the liquid to be transferred and the transmission characteristic changes, the leakage of the liquid is prevented. When the response signal is transmitted from the transponder when the event occurs, the attenuation of the response signal radio wave increases, and the monitoring person cannot receive the response signal radio wave from the transponder. This makes it possible to detect that the detection target has come into contact.

According to a ninth aspect of the present invention, there is provided the transponder unit according to the seventh aspect, wherein the transponder unit changes the resonance frequency of the antenna when the first transponder comes into contact with a liquid.

According to the transponder unit, when a liquid comes into contact with the first transponder, the resonance frequency and the transmission frequency of the antenna shift to frequencies higher or lower than normal frequencies. For this reason, the matching state between the antenna and the transponder body deteriorates, the reach of radio waves radiated from the antenna is shortened, and even if an interrogation signal is transmitted to the transponder, a response signal from the transponder can be received. Disappears. This makes it possible to detect that the detection target has come into contact.

According to a tenth aspect of the present invention, there is provided the transponder unit according to the ninth aspect, wherein the first transponder includes the transponder unit according to any one of the first to fifth aspects.

According to the transponder unit, the above structure reduces the magnetic flux density generated around the antenna, so that the "Q" of the antenna can be set to a low value, for example, a value of about 10. Become.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an external perspective view showing a transponder according to a first embodiment of the present invention, FIG. 2 is an external perspective view showing a transponder element, FIG. 3 is a plan view showing a transponder,
FIG. 4 is a sectional view taken along line AA in FIG.

In the figure, reference numeral 10 denotes a transponder, which is constituted by sandwiching a transponder element 11 and a loop antenna 12 between two films 13 and 14.

The films 13 and 14 have, for example, a width (W1)
Is formed of a polyimide film having a length of 30 mm and a length (L1) of 100 mm.
Are formed by printing. Also, the transponder element 11
The two films 13 and 14 are bonded with a resin.

As shown in FIG. 2, the transponder element 11 is a transponder element body 1 made of a semiconductor chip.
5 and a rectangular parallelepiped resin package 1 covering the periphery thereof
6.

As shown in FIGS. 3 and 4, the antenna 12 is made of a coil-shaped conductor 12a printed on a film 13 and has a thickness (Th) of 20 μm.
m and the width (W2) are set to 2 mm, and the length is set to resonate at 13.56 MHz of the transmission / reception frequency. The antenna 12 is formed by spirally arranging a conductor 12a, and at least a part of the conductor 12a is arranged close to another part with a space of a predetermined distance or less. .

By making the structure of the antenna 12 as described above, the "Q" of the antenna 12 is set to a low value, for example, a value of about 10. To realize such a low "Q", it is necessary to adopt a structure in which the magnetic flux density is low. For this reason, the width (W1) of the printed wiring conductor 12a forming the antenna 12 is set to be larger than the thickness (Th) so that the magnetic flux generated in the antenna 12 is not concentrated at one place.

FIG. 5 is a block diagram showing an electric circuit of the transponder 10. As shown in FIG. In the figure, reference numeral 10 denotes a transponder, which includes an antenna 12, an antenna switching device 21, and a rectifier circuit 2.
2, a central processing unit 23, a storage unit 24, a transmission unit 25, and a detection unit 26.

The antenna switch 21 is composed of, for example, an electronic switch, and is used to connect either the rectifier circuit 22 or the transmitter 25 to the antenna 12.
Connection switching is performed by a control signal output from the central processing unit 23. The antenna switch 21 connects the antenna 12 and the rectifier circuit 22 when the central processing unit 23 is not operating, and connects the antenna 12 and the transmitting unit 25 when the central processing unit 23 is operating.

The rectifier circuit 22 includes diodes 221 and 222, a capacitor 223, and a resistor 224, and forms a well-known full-wave rectifier circuit. The antenna 12 is connected to an input side of the rectifier circuit 22 via an antenna switch 21. The rectifier circuit 22 rectifies a high-frequency current induced in the antenna 12 and converts it into a DC current, which is output as a drive power source for the central processing unit 23, the storage unit 24, and the transmission unit 25.

The central processing unit 23 includes a well-known CPU 231 and a digital / analog (hereinafter, referred to as D / A) converter.
It consists of 232. The CPU 231 reads information stored in the storage unit 24 composed of a semiconductor memory such as an EEPROM when driven by being supplied with power, and outputs this information to the transmission unit 25 via the D / A converter 232.

The transmitting section 25 includes an oscillation circuit 251 and a modulation circuit 252.
And a high frequency amplifier circuit 253, and oscillates by the oscillation circuit 251, for example, a 13.56 MHz carrier wave.
Based on the information signal input from the central processing unit 23, the signal is modulated by the modulation circuit 252 and supplied to the antenna 12 via the high-frequency amplifier circuit 253 and the antenna switch 21.

The detector 26 comprises a diode 261 and an A / D converter 262. The anode of the diode 261 is connected to the antenna 1
2 and the cathode is connected to the CPU 231 of the central processing unit 23 via the A / D converter 262.

Next, the operation of the transponder having the above configuration will be described.

When a leak of liquid has occurred, a predetermined number of the transponders 10 are located in a portion or a range where the leak is to be detected.
Is installed. By transmitting an interrogation signal to these transponders using a scanner (interrogation signal generation and response signal receiver) whose transmission and reception frequency is set to 13.56 MHz, liquid leakage can be detected.

That is, when an electromagnetic wave of a high-frequency signal (interrogation signal) requesting a response signal from the scanner to the transponder 10 is radiated, this electromagnetic wave is transmitted to the transponder 10.
, And a high-frequency current is induced in the antenna 12.

The high-frequency current induced in the antenna 12 is rectified by the rectifier circuit 22 and supplies power to the central processing unit 23, the storage unit 24, and the transmission unit 25 inside the transponder 10.

Thus, when the CPU 231 starts driving, the antenna switch 21 is switched to a transmittable state, and the CPU 231 reads out information stored in the storage unit 24 in accordance with a preset program, and reads this information. Is output to the transmitting unit 25.

The transmitting section 25 modulates the carrier based on the read information and supplies the modulated carrier, that is, a high-frequency signal to the antenna 12. Thereby, the antenna 12
The electromagnetic wave of the response signal is radiated.

Thus, the scanner is connected to the transponder 1
The electromagnetic wave (response signal) radiated from 0 can be received, and it can be seen that the liquid is not in contact with the transponder 10.

As described above, the transponder 1 having the above configuration
0 performs normal communication when the liquid is not in contact.

On the other hand, when the liquid comes into contact with the transponder 10, as shown in FIG. 6, a capacitance C1 is generated by the liquid between the adjacent conductors 12a constituting the antenna 12, so that the resonance frequency and the transmission frequency of the antenna 12 are changed. Is 1
The frequency shifts to a frequency higher or lower than 3.56 MHz. For this reason, the matching state between the antenna 12 and the transmitting unit 25 is deteriorated, the reach of radio waves radiated from the antenna 12 is shortened, and the scanner cannot receive a response signal from the transponder 10. This makes it possible to detect that the liquid to be detected is in contact with the transponder, that is, that leakage of the liquid has occurred.

The transmission and reception frequency of 13.56 MHz and the dimensions of the antenna 12 are merely examples,
The values are not limited to these values, and it suffices that the transmission characteristics (the resonance frequency of the antenna) change when the liquid comes into contact with the liquid.

The difference between the resonance frequency and the transmission frequency of the antenna 12 of the transponder 10 differs depending on the type of the liquid that comes into contact with the transponder 10. For example, when the liquid is heavy oil, the frequency shifts to a higher frequency, and when the liquid is water or seawater, the frequency shifts to a lower frequency. By detecting the shift of the transmission frequency, the type of liquid can be detected.

Next, a second embodiment of the present invention will be described.

In the second embodiment, the transponder 10 of the first embodiment is covered with a non-woven fabric. FIG. 7 is a cross-sectional view illustrating the transponder 30 of the second embodiment, and is a view similar to FIG. 4 of the first embodiment. In the figure, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference between the first embodiment and the second embodiment is that the antenna 12
Nonwoven fabric 31 on films 13 and 14 so as to cover the entirety of
That is,

Since the nonwoven fabric 31 is a member through which the liquid to be detected easily penetrates, the liquid can be brought into contact with the antenna even when the amount of leaked liquid (liquid to be detected) is very small. Can be easily detected. Further, the nonwoven fabric 31 is easily available, and the cost can be kept low.

In this embodiment, a nonwoven fabric is used as the member through which the liquid easily penetrates, but a member other than the nonwoven fabric may be used.

Next, a third embodiment of the present invention will be described.

FIG. 8 is an external perspective view showing a transponder unit according to the third embodiment, FIG. 9 is a plan view, and FIG.
3 is a partial cross-sectional view taken along line AA of FIG.

In the figure, reference numeral 40 denotes a transponder unit, in which a first transponder 41 and a second transponder 42 are integrated by sandwiching them between films 43 and 44.

The films 43 and 44 have, for example, a width (W2)
Is made of a polyimide film having a length of 100 mm and a length (L2) of 100 mm, and is bonded by a resin with the transponders 41 and 42 interposed between the upper and lower films 43 and 44.

The transponder 41 has substantially the same configuration as that of the first embodiment, and the transponder element 1
1 and a loop-shaped antenna 12.

The transponder 42 is composed of a transponder element 51 composed of a semiconductor chip and an antenna line 52.

The structure of the electronic circuit formed in the transponder element 51 is the same as that of the first embodiment, and the transmission / reception frequency is 13.56 MHz.

These two transponders 41 and 42
Can be identified using unique identification information (ID).

As shown in FIGS. 9 and 10, the antenna wire 52 of the second transponder 42 is formed by bundling conductive wires having a diameter of 0.2 mm and covered with an insulating material.
The length is set to resonate at 13.56 MHz of the transmission / reception frequency.

By making the structure of the antenna wire 52 as described above, the “Q” of the antenna wire 52 can be set to a high value,
For example, a value of about 100 is set. In order to realize such a high "Q", a structure in which the magnetic flux is concentrated at one place and the magnetic flux density is high may be used.

The transponder 42 having the above-described structure performs normal communication with the scanner when it is not in contact with the liquid to be detected. Further, even if the liquid to be transferred comes into contact with the transponder 42, almost no capacitance is generated between the adjacent conductors of the antenna wire 52 wound in a loop shape due to the contacted liquid. The resonance frequency hardly deviates from 13.56 MHz.
Further, the attenuation of communication radio waves having a frequency of 13.56 MHz by liquid is small (when the liquid is heavy oil, the attenuation rate is about 2%).
0 dB), the communication can be performed as usual even when the transponder 42 is covered with the liquid.

Therefore, in the third embodiment, it is possible to detect that the liquid has contacted the transponder 41 by communicating with the first transponder 41 as in the first embodiment. Further, by communicating with the second transponder 42, the position where the transponder unit 40 is installed can be specified, and the transponder unit 40 is covered with the liquid, and the communication with the first transponder 41 is interrupted. Also the second transponder 4
2 can access the information in the memory.

The transmission and reception frequency of 13.56 MHz of the second transponder 42 and the configuration of the antenna line 52 are merely examples, and the present invention is not limited thereto. It is only necessary to be able to perform the same communication as.

Further, by providing a member such as a nonwoven fabric which easily penetrates the liquid so as to cover the first transponder 41, the amount of the leaked liquid (liquid to be detected) can be reduced similarly to the second embodiment. Since the liquid can be brought into contact with the antenna even when the amount is small, the liquid can be easily detected.

Next, a fourth embodiment of the present invention will be described.

FIG. 11 is an external perspective view showing a transponder unit 60 according to the fourth embodiment. In the figure,
The same components as those in the third embodiment described above are denoted by the same reference numerals, and description thereof will be omitted. The difference between the third embodiment and the fourth embodiment is that the first transponder 4
Transponder 7 whose transmission / reception frequency is 2 GHz instead of 1
That is, 0 was used.

The first transponder 70 has substantially the same configuration as that of the first embodiment described above, and includes a transponder element 71 composed of a semiconductor chip and a loop antenna 7.
2 is comprised.

The configuration of the electronic circuit formed in the transponder element 71 is the same as that of the first embodiment, except that the transmission / reception frequency is set to 2 GHz.

These two transponders 42 and 70
Can be identified using unique identification information (ID).

The transmission / reception frequency of the first transponder 70 in the above-described configuration is set to 2 GHz for the following reason. That is, in a normal state where the first transponder 70 is not in contact with the liquid, the radio wave of 2 GHz transmitted from the scanner reaches the transponder 70. As a result, the transponder 70 can receive this radio wave and the scanner can receive the response signal transmitted from the transponder 70.

When the first transponder 70 is covered with a liquid to be detected (for example, heavy oil), as shown in FIG. 12, a 2 GHz radio wave (high frequency) is -6 dB when transmitted through the liquid. It receives the above attenuation. FIG. 12 is a diagram showing the high-frequency attenuation rate of heavy oil, with the horizontal axis representing the communication frequency and the vertical axis representing the attenuation rate.

Thus, when the transponder 70 is covered with heavy oil, the radio wave of the interrogation signal radiated from the scanner is attenuated by the heavy oil and the first transponder 70
, Or even if it does, it will be a very weak radio wave, and it will not be possible to give the energy for driving the first transponder 70. Further, even if the driving energy can be barely applied to the first transponder 70, the response signal from the first transponder 70 is attenuated by the heavy oil and cannot reach the scanner. Cannot be received. For these reasons, the transmission and reception frequency of the first transponder 70 is set to 2 GHz.

Therefore, also in the fourth embodiment, the third
Similarly to the embodiment, the communication with the first transponder 70 can detect that the liquid has contacted the transponder 70. Further, by communicating with the second transponder 42, the position where the transponder unit 60 is installed can be specified, and the transponder unit 60 is covered with the liquid, and the communication with the first transponder 70 is interrupted. Can also access information in the memory of the second transponder 42.

The transmission / reception frequency of 2 GHz mentioned above is merely an example, and it is preferable to appropriately set the transmission / reception frequency depending on the type of the liquid to be detected. It is desirable to set a frequency at which attenuation is obtained.

The antenna 72 of the transponder 70
Is covered with a member that easily penetrates the liquid, such as a non-woven fabric, so that the liquid can be brought into contact with the antenna even when the amount of leaked liquid (liquid to be detected) is very small as in the second embodiment. Therefore, the liquid can be easily detected.

[0086]

As described above, according to the transponder antennas of the first to fifth aspects of the present invention,
When a detection target such as water or oil comes into contact, the resonance frequency of the antenna can be easily shifted to a frequency higher or lower than a normal frequency. Accordingly, when the detection target comes into contact with the antenna, a response signal from the transponder cannot be received even if an interrogation signal is transmitted to the transponder, so that it is possible to detect that the detection target has touched the antenna. . Further, since the magnetic flux density generated around the antenna is reduced by the structure of the present antenna, the "Q" of the antenna can be set to a low value, for example, a value of about 10 or so.

According to the transponder antenna of the second aspect, in addition to the above effects, it is possible to configure an antenna that resonates at the transmission / reception frequency with a minimum area or volume.

According to the antenna for a transponder of the third aspect, in addition to the above-described effects, it is possible to prevent the deterioration of the strip conductor without changing the above-mentioned characteristics.

According to the antenna for a transponder according to the fourth and fifth aspects, in addition to the above effects, even if the amount of the liquid is very small, it can be easily detected.

According to the transponder of the sixth aspect, the resonance frequency of the antenna can be easily shifted to a frequency higher or lower than a normal frequency by contact with a detection target such as water or oil. it can. This allows
When the detection target comes into contact with the antenna, a response signal from the transponder cannot be received even if an interrogation signal is transmitted to the transponder. Therefore, it is possible to detect that the detection target has touched the antenna.

According to the transponder unit of the present invention, the communication with the first transponder is disabled, so that an object to be detected such as water or oil comes into contact with the first transponder. Can be detected. Further, the communication with the second transponder which can perform the normal communication even when the liquid comes into contact makes it possible to specify the installation position of the transponder unit, and when the communication with the first transponder cannot be performed, Necessary communication can be performed by the two transponders.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a transponder according to a first embodiment of the present invention.

FIG. 2 is an external perspective view showing the transponder element according to the first embodiment of the present invention.

FIG. 3 is a plan view showing the transponder according to the first embodiment of the present invention.

FIG. 4 is a sectional view taken along line AA in FIG. 3;

FIG. 5 is a configuration diagram illustrating an electric circuit of the transponder according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a detection operation according to the first embodiment of the present invention.

FIG. 7 is a sectional view showing a transponder according to a second embodiment of the present invention;

FIG. 8 is an external perspective view showing a transponder unit according to a third embodiment of the present invention.

FIG. 9 is a plan view showing a transponder unit according to a third embodiment of the present invention.

FIG. 10 is a sectional view taken in the direction of arrows AA in FIG. 9;

FIG. 11 is an external perspective view showing a transponder unit according to a fourth embodiment of the present invention.

FIG. 12 is a frequency characteristic diagram showing a high-frequency attenuation rate of heavy oil according to the present invention.

[Explanation of symbols]

10 transponder, 11 transponder element, 1
2 ... antenna, 12a ... conductor, 13,14 ... film,
15: Transponder element body, 16: Package, 2
DESCRIPTION OF SYMBOLS 1 ... Transmission / reception antenna, 21 ... Antenna switch, 22 ...
Rectifier circuit, 23 central processing unit, 24 storage unit, 25 transmission unit, 26 detection unit, 30 transponder, 31 nonwoven fabric, 40 transponder unit, 41 first transponder, 42 second transponder , 43, 4
4 Film, 51 transponder element, 52 antenna line, 60 transponder unit, 70 first transponder, 71 transponder element, 72 antenna.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G01S 13/76 G01S 13/80 13/79 H01Q 1/38 F term (reference) 2G067 CC02 CC03 DD24 DD25 EE13 5J046 AA03 AA06 AA07 AB11 PA07 5J070 AH31 AJ13 BC23 BC29 BC35 BC36

Claims (10)

[Claims] An antenna which is connected to a transponder main body having a transmitting / receiving means for transmitting a response signal when receiving an interrogation signal by an electromagnetic wave of a predetermined frequency, and constitutes a transponder together with said transponder main body, comprising an insulating plate or A substrate made of a film, comprising a band-shaped conductor formed on the substrate, wherein the band-shaped conductor has an extremely large width with respect to its thickness, and at least a part of the band-shaped conductor is formed with respect to other portions. An antenna for a transponder, which is arranged close to and spaced apart by a predetermined distance or less. 2. The transponder antenna according to claim 1, wherein said strip-shaped conductor is formed in a spiral shape. 3. The transponder antenna according to claim 1, wherein a film is attached to the surface of the substrate on which the strip conductor is formed so as to sandwich the strip conductor. 4. The transponder antenna according to claim 1, wherein a member through which liquid easily penetrates is provided on at least a surface of the substrate on which the strip-shaped conductor is formed. 5. The transponder antenna according to claim 4, wherein a nonwoven fabric is used as the member through which the liquid easily permeates. 6. A transponder comprising a transmitting / receiving means for transmitting a response signal when receiving an interrogation signal by an electromagnetic wave of a predetermined frequency, and an antenna connected to the transmitting / receiving means. A transponder comprising the antenna according to any one of the preceding claims. 7. A transponder unit comprising two or more transponders for transmitting and receiving a radio wave of a predetermined frequency and transmitting a response signal when receiving the radio wave of the frequency, wherein the transponder unit emits a signal when it comes into contact with a liquid. A transponder unit, comprising: a first transponder whose characteristics are changed; and a second transponder that transmits and receives radio waves even when it comes into contact with liquid. 8. The transponder unit according to claim 7, wherein the first transponder is a transponder that transmits and receives radio waves having a frequency that causes attenuation above a predetermined value when transmitted through a liquid. 9. The transponder unit according to claim 7, wherein the first transponder is a transponder whose resonance frequency changes when it comes into contact with liquid. 10. The transponder unit according to claim 9, wherein the first transponder includes the antenna according to any one of claims 1 to 5.