JP7332329B2 - RF communication system - Google Patents

Description

The present disclosure relates to RF communication systems.

When freezing food in a freezer, there is a method in which the food is continuously frozen while being conveyed by a conveyor within the freezer. The conveyor belt of this conveyor may derail from the track, and as a method of detecting this, there is a method of arranging a proximity sensor near the conveyor belt and detecting the presence or absence of derailment with the proximity sensor. However, the inside of the freezer is usually maintained at an extremely low temperature of −30° C. or less, and is exposed to a large temperature change that rises to room temperature or higher during the defrost operation, and is exposed to a high humidity environment during cleaning inside the freezer. As a result, there have been cases where moisture enters from the connecting portion of the power supply line and the signal line connected to the proximity sensor, causing the proximity sensor to malfunction. If the proximity sensor breaks down, even if the conveyor derails, it cannot be detected, so the derailment spreads, and eventually the conveyor's driving device is overloaded, resulting in an abnormal stop. A lot of labor and time are required to recover from the derailment that has spread, and there is a problem that the productivity of the freezer is lowered.

Therefore, without using a proximity sensor, as disclosed in Patent Documents 1 to 3, the information of the RF tag provided on the side of the object to be detected is transmitted to a reader at a remote position without contact by an induced electromagnetic field or electromagnetic wave. It is conceivable to employ an RFID system that can be supplied to

JP-A-07-168985 JP 2013-142675 A JP 2016-71462 A

However, in the case of RF communication systems, if the RF tag is a passive type RF tag that is not equipped with a battery, there is a problem that the communication area is limited even if an ultrahigh frequency (UHF) band electromagnetic wave, which has a relatively long communication range, is used. There is This imposes various restrictions on the arrangement of the reader/writer-side device. On the contrary, in the case of an active type RF tag equipped with a battery, there is a problem that workability is lowered because the cost is high, the size is large, and the battery needs to be replaced.
In addition, when the RF tag is placed in a harsh environment such as a freezing temperature where the temperature and pressure are greatly different from normal temperature and normal pressure, or in an environment in which the human body cannot survive, the reader side device is not as durable as the RF tag. There is a problem that it cannot be placed near the

An object of an embodiment of the present disclosure is to extend the communication distance by a simple means in an RF communication system and increase the degree of freedom in arranging reader-side devices.

(1) An RF communication system according to one embodiment includes:
with the leader;
a first coil provided within a communication range of the reader;
a second coil connected to the first coil;
the reader and the first coil are arranged with a partition with respect to the second coil;
The reader is configured to read, via the first coil, changes in the magnetic field around the second coil due to penetration of the RF tag into the communication range of the second coil.
In this specification, the term “reader” refers to a device that only has the function of reading information held by RF tags. When applied to a communication system that needs to write a number, it includes a function as a reader/writer capable of not only reading but also writing information to the RF tag.

According to the above configuration (1), the use of the RFID system eliminates the need for a proximity sensor, so it is possible to eliminate detection impossibility and erroneous detection due to failure of the proximity sensor. In addition, by lengthening the conductor connecting the first coil and the second coil and increasing the distance between the first coil and the second coil, the communication distance of the tag information can be extended. Restrictions on location can be relaxed. Furthermore, by arranging the first coil and the second coil across the partition wall, the RF tag is surrounded by the partition wall, and even if the RF tag is placed in a place that is difficult for workers to enter, the reader-side device can be placed outside the partition wall. It can be placed in a place suitable for operation. This can expand the application of RF communication systems.

(2) In one embodiment, in the configuration of (1),
A space inside the wall surrounded by the partition is in an environment different in temperature, pressure or atmosphere from the outside of the partition,
The second coil and the RF tag are arranged in the space inside the partition, and the reader and the first coil are arranged outside the partition.
According to the above configuration (2), the inner space of the partition wall is under a severe environment where the temperature, pressure, etc. are greatly different from normal temperature and normal pressure, or under an environment harmful to the human body, and the RF tag and the second coil are Even in such an environment, the distance between the first coil and the second coil can be extended, so the reader and the first coil can be placed in an environment suitable for operation outside the partition wall.

(3) In one embodiment, in the configuration of (1) or (2),
An object to be detected on which the RF tag is installed, wherein a plurality of the RF tags are provided at different parts of the different objects or the same object,
a plurality of second coils provided corresponding to each of the plurality of RF tags;
a plurality of first coils connected to each of the plurality of second coils;
Prepare.
Here, "the RF tag is installed" refers to the case where the RF tag is directly attached to the object to be detected, and the case where the RF tag is not in contact with the object to be detected and corresponds to the operation of the object to be detected. It includes the case where it is arranged close to a position where the position can be changed.

According to the configuration of (3) above, it is possible to simultaneously obtain a plurality of pieces of information from a plurality of RF tags provided at different parts of different objects to be detected or the same object to be detected. Since a plurality of independent coil assemblies including coils are provided, the induced current generated in each first coil is distributed to the second coils of the other coil assemblies to reduce the amount of current flowing through the second coils of the same coil assembly. It will not be lost. Therefore, the reader can accurately read the information sent from each RF tag.

(4) In one embodiment, in the configuration of (1) or (2),
An object to be detected on which the RF tag is installed, wherein a plurality of the RF tags are provided at different parts of the different objects or the same object,
a plurality of second coils provided corresponding to each of the plurality of RF tags;
one of the first coils connected to each of the plurality of second coils;
Prepare.
According to the configuration (4) above, since it is sufficient to provide one first coil for a plurality of second coils, the cost of the coil assembly can be reduced.

(5) In one embodiment, in the configuration of (4),
A switch is provided for connecting or disconnecting the antenna conductor connected to each of the plurality of second coils.
According to the configuration (5), since the switch is provided, only the RF tag for which tag information is desired can be connected to the reader side, and other antenna conductors can be disconnected from the reader side. As a result, the induced current generated by the first coil flows only through the second coil for which the tag information is desired, and does not flow through the other antenna conductors, thereby increasing the distance between the second coil and the first coil. By switching the switch, the reader can read tag information sent from a plurality of RF tags.

(6) In one embodiment, in any one of the configurations (1) to (5),
a storage unit for storing information obtained by the reader from the RF tag;
a display unit that displays the information stored in the storage unit;
Prepare.
According to the configuration (6) above, the tag information sent to the reader can be stored in the storage section and displayed on the display section as needed.

(7) In one embodiment, in any one of the configurations (1) to (6),
A support member that movably supports the RF tag,
The support member is configured such that the RF tag can be arranged within or outside the communication range of the second coil according to the first state or the second state of the object.
According to the configuration (7) above, by including the support member, the RF tag is arranged within or outside the communication range of the second coil according to the first state or the second state of the object to be detected. Therefore, the reader can read whether the object is in the first state or the second state.

(8) In one embodiment, in the configuration of (7),
The support member is composed of a rod-shaped body that is rotatably supported around an axis,
The rod-shaped body is arranged so that one end is in contact with the object to be detected, and the RF tag is attached to the other end,
When the object to be detected exists at the first position, the RF tag is arranged within the communication range of the second coil. are configured to be placed outside the communication range of
With configuration (8) above, the reader can read that the object to be detected is present at the first position or the second position by using a simple support member made of a rod-shaped body.

(9) In one embodiment, in any one of the configurations (1) to (8),
The object to be detected, which is the detection target on which the RF tag is installed, is composed of a conveyor,
A plurality of the RF tags are arranged at different locations in the conveying direction of the conveyor.
According to the configuration (9) above, since a plurality of RF tags are provided at different locations in the conveying direction of the conveyor, it is possible to obtain information on the operation of the conveyor over a wide area in the conveying direction of the conveyor.

(10) In one embodiment, in the configuration of (9),
When the conveyor belt of the conveyor is in a normal position, the RF tag is arranged within the communication range of the second coil, and when the conveyor belt is derailed, the RF tag is arranged out of the communication range of the second coil. configured to be
According to the above configuration (10), it is possible to detect the presence or absence of derailment of the conveyor belt, and even when an abnormality such as a broken line in the antenna conductor occurs, the same information is supplied to the reader. It can be detected as an occurrence.

(11) In one embodiment, in the configuration of (9) or (10),
The reader comprises a storage unit for storing information obtained from the RF tag,
A plurality of the RF tags are arranged at different locations in the conveying direction of the conveyor,
each of the plurality of RF tags holds a unique identification number;
At least the unique identification number and arrangement location of each of the plurality of RF tags are stored in the storage unit.
According to the above configuration (11), the reader side can read from which place the RF tag arranged the tag information supplied from the RF tag.

(12) In one embodiment, in any one of the configurations (1) to (11),
An object to be detected, which is a detection target on which the RF tag is installed, is an object to be conveyed by a conveyor,
The RF tag is attached to the transported object.
According to the configuration (12) above, it is possible to identify from which object the tag information supplied from the RF tag is supplied. Therefore, by collating with the tag information from the RF tag provided on the conveyor, for example, when the object to be conveyed is food, quality control such as traceability of the food becomes possible.

According to some embodiments, an RF communication system using electromagnetic waves is used, and the communication distance can be extended by a simple means. readable by This makes it possible to relax restrictions on the placement of the reader-side device and expand the applications of the RF communication system.

1 is a schematic diagram of an RF communication system according to one embodiment; FIG. 1 is a schematic diagram of an RF communication system according to one embodiment; FIG. 1 is a schematic diagram of an RF communication system according to one embodiment; FIG. 1 is a schematic diagram of an RF communication system according to one embodiment; FIG. FIG. 4 is a schematic diagram of a support member of an RF tag according to one embodiment; 1 is a schematic diagram of an RF communication system according to one embodiment applied to a conveyor; FIG. It is a schematic diagram which shows the tension adjustment apparatus of a conveyor belt. 8 is a schematic diagram of an RF communication system applied to the tensioning device of FIG. 7; FIG. FIG. 4 is a schematic diagram of a support member of an RF tag according to one embodiment; FIG. 4 is a schematic diagram of a support member of an RF tag according to one embodiment;

Several embodiments of the present invention will now be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as the embodiment or shown in the drawings are not meant to limit the scope of the present invention, but merely illustrative examples.
For example, expressions denoting relative or absolute arrangements such as "in a direction", "along a direction", "parallel", "perpendicular", "center", "concentric" or "coaxial" are strictly not only represents such an arrangement, but also represents a state of relative displacement with a tolerance or an angle or distance to the extent that the same function can be obtained.
For example, expressions such as "identical", "equal", and "homogeneous", which express that things are in the same state, not only express the state of being strictly equal, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state.
For example, expressions that express shapes such as squares and cylinders do not only represent shapes such as squares and cylinders in a geometrically strict sense, but also include irregularities and chamfers to the extent that the same effect can be obtained. Shapes including parts etc. shall also be represented.
On the other hand, the expressions "comprising", "comprising", "having", "including", or "having" one component are not exclusive expressions excluding the presence of other components.

FIG. 1 illustrates an RF communication system 10 (10A) according to one embodiment. The RF communication system 10 ( 10A) includes a reader/writer 12 and a coil assembly 14 . The coil assembly 14 includes a first coil 15 and a second coil 16 that are made of conductive antenna wires. The first coil 15 and the second coil 16 are connected by a conductor wire, and the first coil 15 is provided within the communication range of the reader/writer 12 . The reader/writer 12 and the first coil 15 are arranged with the partition wall 17 interposed with respect to the second coil 16 . The second coil 16 is arranged near the RF tag 20 so that the RF tag 20 can enter the communication range of the second coil 16 . Due to the magnetic field generated by the reader/writer 12, an induced current is generated in the first coil 15 by the principle of electromagnetic induction. When this induced current flows through the second coil 16 , a magnetic field is generated in the second coil 16 . When the RF tag 20 enters the communication range of the second coil 16, it receives power transmission and activates the IC in the RF tag. The reader/writer 12 reads the resulting change in the magnetic field around the second coil, so that the reader/writer 12 can identify the information on the object 18 held by the RF tag 20 .

According to the above configuration, use of the RFID system eliminates the need for a proximity sensor, thereby eliminating detection impossibility and erroneous detection due to failure of the proximity sensor. Further, by increasing the distance between the first coil 15 and the second coil 16, it is possible to extend the communication distance of the tag information, so that restrictions on the location of the reader/writer-side device can be relaxed. Since the induced current flowing between the first coil 15 and the second coil 16 is reduced by the resistance of the antenna conductor that constitutes the first coil 15 and the second coil 16, the distance between the first coil 15 and the second coil 16 is is limited. However, as disclosed in Patent Literatures 1 to 3, the communication distance can be extended as compared with communication between the RF tag 20 and the reader/writer 12 using electromagnetic waves. Furthermore, by arranging the first coil 15 and the second coil 16 across the partition wall 17, the object to be detected 18 and the RF tag 20 are surrounded by the partition wall 17, and even if they are placed in a place where it is difficult for workers to enter. , the device on the reader/writer side can be arranged outside the partition wall 17 at a place suitable for operation. This makes it possible to expand the applications of the RF communication system 10 (10A).

An antenna lead wire used in the coil assembly 14 is, for example, a copper wire, an aluminum wire, or the like having a small resistance.

In one embodiment, the inner space Si of the partition wall 17 surrounded by the partition wall 17 is in an environment different in temperature, pressure, or atmosphere from the outside of the partition wall 17, and the second coil 16 and the RF tag 20 are placed in the inner space Si under such an environment. may be placed. Even if the inner space Si is in a severe environment such as a freezer where the temperature, pressure, etc. are greatly different from normal temperature and normal pressure, or even in an environment harmful to the human body, the communication distance can be extended. The writer-side device can be placed in an environment suitable for operation outside the bulkhead 17 .

In one embodiment, power is supplied from the power supply 22 to the reader/writer 12 in the reader/writer-side device. In the above-described embodiment, the reader/writer 12 has the function of not only reading information held by the RF tag 20 but also writing new information into the RF tag 20 . However, if there is no need to write information to the RF tag 20, for example, since only one RF tag 20 is used, there is no need to write identification information such as an identification number to the RF tag 20, or a plurality of RF tags Even if the tag 20 is used, identification information has already been written to each RF tag 20, and in the case where there is no need to write in the future, instead of the reader/writer 12, a reader having a read-only function is used. good too.

In one embodiment, the RF tag 20 uses a passive type without a battery. As a result, there is an advantage that the cost is low, battery replacement is not required, and workability is not lowered.

In one embodiment, as shown in FIG. 1, the control unit 30 includes a programmable logic controller (PLC) 24 having a built-in memory for storing information obtained by the reader/writer 12 from the RF tag 20. , and a display 26 (display unit) for displaying information stored in the memory. Thereby, the tag information sent to the reader/writer 12 can be stored in the memory, and the information stored in the memory can be displayed on the display 26 as required.
In one embodiment, controller 30 incorporates alarm 28 . The alarm device 28 is configured to issue an alarm when the tag information stored in the memory built into the PLC 24 indicates an abnormality in the object 18 to be detected.

In one embodiment, multiple RF tags 20 (20a, 20b, 20c) are provided in the RF communication system 10 (10B) shown in FIG. A plurality of RF tags 20 are provided on different objects 18 to be detected, or, as shown in FIG. In this embodiment, the same number of the second coils 16 (16a, 16b, 16c) are provided corresponding to the plurality of RF tags 20, and the same number of the second coils 16 are separated by the partition walls 17. A first coil 15 (15a, 15b, 15c) is connected. That is, a plurality of independent coil assemblies 14 (14a, 14b, 14c) are configured with the partition walls 17 interposed therebetween.

According to this embodiment, it is possible to simultaneously obtain a plurality of pieces of information from a plurality of RF tags 20 provided at different parts of different objects 18 to be detected or the same object 18 to be detected. Since a plurality of independent coil assemblies 14 including two coils 16 are provided, the induced current generated in each first coil 15 is distributed to the second coils 16 of the other coil assemblies 14 to form the second coils of the same coil assembly 14. The amount of current flowing through 16 will not decrease. Therefore, the reader/writer 12 can accurately read the information sent from each RF tag 20 .

The object to be detected 18 (18a) shown in FIG. 2 is a spiral conveyor in which a conveyor belt 19 (19a) is arranged in a vertical spiral. Three RF tags 20 (20a, 20b, 20c) are provided on the upper, middle and lower conveyor belts 19 (19a), respectively. The state of the belt 19 (19a) can be monitored.

3 and 4 show RF communication systems 10 (10C, 10D) according to different embodiments, respectively. In these embodiments, multiple RF tags 20 (20a, 20b, 20c) are provided on different objects 18 to be detected, or, as shown in FIGS. provided in different parts of the In addition, a plurality of second coils 16 (16a, 16b, 16c) are provided for each of the plurality of RF tags 20, but the configuration different from the RF communication system 10 (10B) is each coil assembly 14 (14A, 14B) is configured by connecting one first coil 15 to a plurality of second coils 16 (16a to 16c) with a partition wall 17 interposed therebetween.
According to this embodiment, it suffices to provide one first coil 15 for a plurality of second coils 16 (16a to 16c). can be

In the embodiment shown in FIG. 3, similarly to the embodiment shown in FIG. 2, the object 18 (18a) to be detected is configured by a spiral conveyor having a spiral conveyor belt 19 (19a). Three RF tags 20 (20a to 20c) are provided on the upper, middle and lower conveyor belts 19 (19a), respectively, so that the status of the conveyor belt 19 (19a) can be monitored at these three locations.

In the embodiment shown in FIG. 4, the object to be detected 18 (18a) is configured by a conveyor having a conveyor belt 19 (19b) forming a horizontal conveying surface. The conveyor belt 19 (19b) moves in the direction of the arrow, and the three RF tags 20 (20a to 20c) are provided at three locations on the conveying direction upstream, midstream and downstream sides of the conveyor belt 19 (19b). ing. Therefore, the state of the conveyor belt 19 (19a) can be monitored at these three locations.

In one embodiment, as shown in FIGS. 3 and 4, a plurality of second coils 16 (16a, 16b, 16c) are provided for a plurality of RF tags 20 (20a, 20b, 20c). A switch 32 is provided for connecting or disconnecting the antenna conductor connected to the second coil 16 . According to this embodiment, since the switch 32 is provided, only the RF tag 20 for which tag information is desired can be connected to the first coil 15, and other antenna conductors can be disconnected from the first coil 15. FIG. As a result, the induced current generated by the first coil 15 flows only through the second coil 16 for which the tag information is desired and does not flow through the other antenna conductors. In addition, the reader/writer 12 can read the tag information sent from the plurality of RF tags 20 by switching the switches.

In one embodiment, as shown in FIG. 5, a support member 34 is provided corresponding to the object 18 to be detected and movably supports the RF tag 20 . The support member 34 is configured so that the RF tag 20 can be arranged within or outside the communication range R of the second coil 16 according to the first state A or the second state B of the object 18 to be detected. According to this embodiment, the RF tag 20 is arranged within or outside the communication range R of the second coil 16 by the support member 34 depending on the first state A or the second state B of the object 18 to be detected. Therefore, the reader/writer 12 can read that the object 18 is in the first state A or the second state B. FIG.

In one embodiment, as shown in FIG. 5, the support member 34 is composed of a rod-like body 36 that is rotatably supported about an axis. The rod-shaped body 36 is arranged so that one end is in contact with the object 18 to be detected, and the RF tag 20 is attached to the other end. When the object 18 to be detected exists at the first position A, the RF tag 20 is arranged within the communication range R of the second coil 16. When the object 18 to be detected exists at the second position B, the RF tag 20 It is configured to be placed outside the communication range R of the two coils 16 .
According to this embodiment, the reader/writer 12 can read the tag information of the object 18 existing at the first position A or the second position B by using the simple support member 34 composed of the rod-shaped body 36. can be done.

In one embodiment, as shown in FIGS. 2 to 4, the object to be detected 18 to be detected by the RF tag 20 is configured by a conveyor, and a plurality of RF tags 20 are arranged at different locations in the conveying direction of the conveyor. . According to this embodiment, since a plurality of RF tags 20 are provided at different locations in the conveying direction of the conveyor, information on the conveyor can be obtained over a wide area in the conveying direction of the conveyor.

In one embodiment, when the conveyor belt of the conveyor, which is the object to be detected 18, is in a normal position, for example, at the first position A shown in FIG. , and the RF tag 20 is configured to be positioned outside the communication range R of the second coil 16 when the conveyor belt derails. According to this embodiment, the presence or absence of derailment of the conveyor belt can be detected, and even when an abnormality such as a broken line of the antenna conductor occurs, the same information as when the RF tag 20 is placed outside the communication range R of the second coil 16 can be obtained. is supplied to the reader/writer 12, the reader/writer 12 can read the occurrence of a broken line in the antenna conductor as an abnormality.

In one embodiment, as shown in FIGS. 2 to 4, a plurality of RF tags 20 are arranged at different locations on the conveyor belt 19 (19a, 19b) in the conveying direction of the conveyor, which is the object to be detected 18, and a plurality of RF tags 20 are arranged. Each tag 20 holds a unique identification number. Then, the unique identification numbers and arrangement locations of at least the plurality of RF tags 20 are stored in the memory built into the PLC 24 . According to this embodiment, the reader/writer 12 side can read the tag information supplied from the RF tag 20 at which place on the conveyor the information is from the RF tag 20 .

In one embodiment, the object to be detected 18 to be detected with the RF tags 20 installed is the object 40 to be conveyed by the conveyor, and the plurality of RF tags 20 are attached to a plurality of different objects 40 to be conveyed. be. According to this embodiment, since each RF tag 20 has a unique identification number, it is possible to identify from which transferred object 40 the tag information supplied to the reader/writer 12 is supplied. As a result, it is possible to detect the position of a specific object 40 in the conveying direction of the conveyor, and to detect that the objects 40 have piled up. Moreover, by collating the tag information of the RF tag 20 provided on the transferred object 40 with the tag information from the RF tag 20 provided on the conveyor, for example, the transferred object 40 is placed in the freezer. When the food is transported by a conveyor and frozen during transportation, quality control such as traceability of the food becomes possible.

Conventionally, as a means of emergency stop when an abnormality occurs in a spiral conveyor installed in a freezer, a mechanical rope switch was installed in various places on the conveyor, and when an abnormality occurred, a worker who discovered an abnormality pulled the rope. Means are used to bring the conveyor to an emergency stop. In one embodiment, instead of the above means, RF tags 20 are placed throughout the refrigerator as shown in FIG. When an abnormality occurs in the conveyor, the worker pulls the rope 42 to separate the RF tag 20 from the second coil 16, and the reader/writer 12 provided outside the warehouse across the partition wall 17 reads this OFF signal, Configured to stop the conveyor and issue an alarm. A spring member 44 is provided between the RF tag 20 and the rope 42, and the spring member 44 causes the RF tag 20 and the rope 42 to return to their original positions.

As shown in FIG. 7, the conveyor is provided with a device 50 for adjusting the tension of the conveyor belt 19 . The tension adjusting device 50 is provided, for example, in the vicinity of a driving roller 46 that drives the conveyor belt 19, and includes a pair of guide rollers 52 and an adjusting roller 54 that can reciprocate so that the distance between the guide rollers 52 is variable. and have. The tension of the conveyor belt 19 can be adjusted by adjusting the distance between the adjustment roller 54 and the guide roller 52 .
In one embodiment, as shown in FIG. 8, the adjustment roller 54 is provided with the RF tags 20, and the second coils 16 (16d, 16e) are positioned facing the RF tags 20 at both ends of the reciprocation of the adjustment roller 54. ) is placed. When the adjustment roller 54 reaches the both end positions, the reader/writer 12 reads the magnetic field change around the second coil 16 due to the penetration of the RF tag 20 and determines that the conveyor belt 19 has become abnormal.

In one embodiment, RF tags 20 are attached to tools used in the freezer, and tag information is read by a reader/writer 12 provided outside the freezer. This can prevent tools from being left behind.

In one embodiment, as shown in FIG. 9, a non-conductive liquid such as pure water is stored in a tank 60, the second coil 16 and the RF tag 20 are placed in the non-conductive liquid, and the first coil 15 and The reader/writer 12 is arranged outside the partition wall 60 a of the tank 60 . The reader/writer 12 can read the tag information while the non-conductive liquid remains non-conductive. On the other hand, when the non-conductive liquid becomes conductive due to contamination of the non-conductive liquid, overcurrent is generated in the non-conductive liquid, and the reader/writer 12 cannot read the information on the RF tag 20 . This makes it possible to detect contamination of the non-conductive liquid or the like. By arranging the combination of the second coil 16 and the RF tag 20 at a plurality of locations within the tank 60, it becomes possible to monitor contamination at a plurality of locations.

FIG. 10 shows an embodiment for detecting the level of the conductive liquid stored in the tank 60. As shown in FIG. In FIG. 10, the second coil 16 (16f) and the RF tag 20 (20d) and the second coil 16 (16g) and the RF tag 20 (20e) are arranged in the tank 60, and the second coil 16 (16f) , 16g) and the first coil 15 and the reader/writer 12 are arranged outside the partition wall 60a of the tank 60. As shown in FIG. The second coil 16 (16f) and the RF tag 20 (20d) are provided to detect the lower liquid level _h1 , and the second coil 16 (16f) and the RF tag 20 (20d) detect the lower liquid level. It is provided so as to sandwich _h1 . The second coil 16 (16g) and the RF tag 20 (20e) are provided to detect the upper limit liquid level _h2 , and the second coil 16 (16g) and the RF tag 20 (20e) detect the upper limit liquid level. It is provided so as to sandwich _h2 .

Since the reader/writer 12 can read the tag information when the liquid level is below the RF tag 20 (20d), therefore, it is detected that the liquid level is below the RF tag 20 (20d) at this time. can. When the liquid level is between the second coil 16 and the RF tag 20, the reader/writer 12 cannot read the tag information. That is, when the liquid level is at the lower liquid level _h1 , the reader/writer 12 cannot read the information of the RF tag 20 (20d), but can read the information of the RF tag 20 (20e). When the liquid level is at the upper liquid level _h2 , the reader/writer 12 cannot read the information of the RF tag 20 (20d) and the RF tag 20 (20e). In this way, the liquid level can be grasped. If only one liquid level is to be detected, a set of the second coil 16 and the RF tag 20 may be provided inside the tank 60 .

In one embodiment, the present invention can be applied to monitoring the open/closed state of opening/closing doors of refrigerators and freezers, opening/closing doors in a vacuum environment where workers cannot approach, and opening/closing doors in a radiation environment, or for inventory management. In this example, the RF tag 20 is provided on the door side, and the second coil 16 is provided on the door frame. The second coil 16 reads the magnetic field change caused by the penetration of the RF tag 20 to read the closed state, and reads the open state when there is no magnetic field change.

According to some embodiments, in an RF communication system, the communication distance can be extended by simple means, the degree of freedom in arranging the reader-side device can be increased, and the applications of the RF communication system can be broadened. can.

10 (10A, 10B, 10C, 10D) RF communication system 12 reader/writer 14 (14A, 14B, 14a, 14b, 14c) coil assembly 15 (15a, 15b, 15c) first coil 16 (16a, 16b, 16c, 16d) , 16e, 16f, 16g) Second coil 17 Partition wall 18 (18a, 18b) Object to be detected 19 (19a, 19b) Conveyor belt 20 (20a, 20b, 20c, 20d, 20e) RF tag 22 Power supply 24 PLC
26 display 28 alarm 30 control unit 32 switch 34 support member 36 bar 40 object to be conveyed 42 rope 44 spring member 46 drive roller 50 tension adjustment device 52 guide roller 54 adjustment roller 60 tank 60a partition wall A first position (first state )
B Second position (second state)
Si Internal space h ₁ Lower limit liquid level h ₂ Upper limit liquid level R Communication range

Claims (10)

with the leader;
a first coil provided within a communication range of the reader;
a second coil connected to the first coil;
the reader and the first coil are arranged with a partition with respect to the second coil;
The reader is configured to read, via the first coil, a change in the magnetic field around the second coil due to penetration of the RF tag into the communication range of the second coil ,
The object to be detected, which is the detection target on which the RF tag is installed, is composed of a conveyor,
The RF tag is arranged within the communication range of the second coil when the conveyor is in a normal position, and the RF tag is arranged outside the communication range of the second coil when the conveyor is derailed. Configured
An RF communication system characterized by: The space inside the partition surrounded by the partition is in an environment different in temperature, pressure or atmosphere from the outside of the partition,
2. The RF communication system according to claim 1, wherein the second coil and the RF tag are arranged inside the partition, and the reader and the first coil are arranged outside the partition. . An object to be detected on which the RF tag is installed, wherein a plurality of the RF tags are provided at different parts of the different objects or the same object,
a plurality of second coils provided corresponding to each of the plurality of RF tags;
a plurality of first coils connected to each of the plurality of second coils;
3. The RF communication system according to claim 1 or 2, comprising: An object to be detected on which the RF tag is installed, wherein a plurality of the RF tags are provided at different parts of the different objects or the same object,
a plurality of second coils provided corresponding to each of the plurality of RF tags;
one of the first coils connected to each of the plurality of second coils;
3. The RF communication system according to claim 1 or 2, comprising: 5. The RF communication system according to claim 4, further comprising a switch for connecting or disconnecting an antenna conductor connected to each of said plurality of second coils. a storage unit for storing information obtained by the reader from the RF tag;
a display unit that displays the information stored in the storage unit;
6. The RF communication system according to any one of claims 1 to 5, comprising: with the leader;
a first coil provided within a communication range of the reader;
a second coil connected to the first coil;
the reader and the first coil are arranged with a partition with respect to the second coil;
The reader is configured to read, via the first coil, a change in the magnetic field around the second coil due to penetration of the RF tag into the communication range of the second coil,
A support member that movably supports the RF tag,
The support member enables the RF tag to be arranged within or outside the communication range of the second coil according to a first state or a second state of an object to be detected, which is a detection target on which the RF tag is installed. An RF communication system, characterized in that: The support member is composed of a rod-shaped body that is rotatably supported around an axis,
The rod-shaped body is arranged so that one end is in contact with the object to be detected, and the RF tag is attached to the other end,
When the object to be detected exists at the first position, the RF tag is arranged within the communication range of the second coil. 8. The RF communication system of claim 7, wherein the RF communication system is configured to be located outside the communication range of the. The object to be detected, which is the detection target on which the RF tag is installed, is composed of a conveyor,
The reader comprises a storage unit for storing information obtained from the RF tag,
A plurality of the RF tags are arranged at different locations in the conveying direction of the conveyor,
each of the plurality of RF tags holds a unique identification number;
9. The RF communication system according to any one of claims 1 to 8, wherein at least the unique identification number and arrangement location of each of the plurality of RF tags are stored in the storage unit. An object to be detected, which is a detection target on which the RF tag is installed, is an object to be conveyed by a conveyor,
9. The RF communication system according to claim 7, wherein said RF tag is attached to said transported object.

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