RFID tags with on / off function

Abstract

We provide RFID tags with an on / off function. [Solution] The RFID tag 1 with on / off function of the present invention comprises an RF chip 20, a conductor part 10, a coil part 30, a reed switch 40, and a magnet 50 that controls the drive of the reed switch. The capacitance inside the RF chip and the coil part form a resonant circuit 60, and the RF chip generates the power necessary for driving from the carrier wave of the reader / writer, and the function of the resonant circuit is turned on / off by changing the relative distance between the reed switch and the magnet and driving the reed switch. In the present invention, a so-called passive type RFID tag is used as the RF chip, and the function of the RFID tag is turned on / off by turning the function of the resonant circuit on / off using the reed switch and magnet. This has the advantage that there is no need to supply power separately for driving the RFID tag.

Description

Technical Field

[0001] The present invention relates to an RFID tag with an on-off function.

Background Art

[0002] An RFID tag used in an RFID (Radio Frequency Identification) system stores an antenna and an RF chip. The antenna receives a carrier wave transmitted from the antenna of a reader / writer, and rides identification data and the like recorded in the RF chip on a reflected wave and returns it to the reader / writer, so that it has a non-contact communication mechanism. [[ID=第十三]] [[ID=第十四]]

[0003] [[ID=第十五]] The uses of RFID tags are various. For example, Patent Document 1 discloses a system that can grasp the operating states of a plurality of valves using an RFID tag. [[ID=第十七]] Specifically, this system includes a detection means for detecting the operation of a valve, an RFID tag for recording the operation information detected by the detection means, and a terminal for reading the valve operation information recorded in the RFID tag. The RFID tag is an active tag incorporating a transceiver connecting a battery and an antenna, and does not transmit operation information until the presence of the terminal is confirmed, and transfers the valve operation information recorded in the RFID tag to the terminal when receiving a signal from the terminal. [[ID=第十九]]

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The aforementioned Patent Document 1 has several problems: the detection means requires power to operate, making it difficult to detect the operation of valves installed in locations where power supply is difficult; and the cost of installing multiple detection means to accommodate multiple valves is high. Furthermore, because it uses active RFID tags, it cannot be used if the battery runs out. Even if a passive RFID tag is used that does not have a built-in battery and operates using the carrier wave from the reader / writer as its power source, the detection means that transmits operational information to the RFID tag still requires power, so the above problem cannot be resolved.

[0006] The present invention aims to provide an RFID tag with an on / off function, taking these problems into consideration. [Means for solving the problem]

[0007] The RFID tag with on / off function of the present invention comprises at least an RF chip, a conductor, a coil, a reed switch, and a magnet that controls the driving of the reed switch. The capacitance inside the RF chip and the coil form a resonant circuit. The RF chip generates the power necessary for driving from the carrier wave of a reader / writer. The function of the resonant circuit is turned on / off by changing the relative distance between the reed switch and the magnet and driving the reed switch. Furthermore, the device is characterized by switching between on and off by changing the relative distance between the reed switch and the magnet, thereby driving the reed switch to change whether or not power generation is possible. Furthermore, the device is characterized in that an elastic body is provided between the reed switch and the magnet, and when an external force is applied, the magnet moves toward the reed switch side while deforming the elastic body, thereby driving the reed switch. Furthermore, it is characterized by comprising a capacitor section connected to the conductor section. [Effects of the Invention]

[0008] This invention uses a so-called passive RFID tag in which the RF chip generates the power necessary for operation from the carrier wave of the reader / writer, and the function of the RFID tag is turned on / off by turning the function of the resonant circuit on / off using a reed switch and a magnet. This has the advantage that there is no need to supply power separately for driving the RFID tag. When turning the RFID tag's functionality on or off, it may be possible to change the situation so that the passive RF chip can generate the power necessary for operation using the carrier wave of the reader / writer, or not. By placing an elastic body between the reed switch and the magnet, and deforming the elastic body with the application of an external force, the magnet is moved towards the reed switch, thereby enabling the RFID tag's function to be turned on / off by removing / applying the external force. By connecting a capacitor to a conductor and bringing the capacitor into contact with the conductive part of the object, the conductive part can also function as an antenna. [Brief explanation of the drawing]

[0009] [Figure 1] Plan view (a) of an RFID tag with an on / off function, plan view of the conductor and coil section (b), and front view (c) of the RFID tag. [Figure 2] Equivalent circuit diagrams of RFID tags (a) and (b) [Figure 3] Plan view (a), front view (b) of an RFID tag covered with an elastic material, front view (c) of a pressed state, and front view (d) showing a modified example of the RFID tag. [Figure 4] A top view (a), a front view (b), a top view (c), and a front view (d) of the RFID tag according to the second embodiment, showing the tag attached to an object. [Figure 5] Equivalent circuit diagrams of RFID tags (a) and (b) [Figure 6] Plan view (a), front view (b), and plan view (c) and front view (d) of a modified RFID tag. [Figure 7] This is a system for detecting the action / non-action of an object, and the front views (a) and (b) show the RFID tag attached to a handle-type valve. [Figure 8] Front view showing a state where RFID tags are attached to a plurality of valves [Figure 9] An object action / non-action detection system, front view (a), plan views (b) and (c) showing a state where an RFID tag is attached to a lever-type valve [Figure 10] An object action / non-action detection system, front view (a), bottom view (b) and (c) showing a state where an RFID tag is attached to a door [Figure 11] Plan view showing a modified example of an RFID tag

Embodiments for Carrying Out the Invention

[0010] [First Embodiment] A first embodiment of an RFID tag with an on / off function of the present invention (hereinafter, may be simply referred to as "RFID tag") will be described with reference to the drawings. As shown in FIGS. 1(a) and (c), the RFID tag 1 includes at least a conductor part 10, an RF chip 20, a coil part 30, a reed switch 40, and a magnet 50.

[0011] The conductor part 10 has a function as an antenna that receives a carrier wave from a reader / writer and also returns a reflected wave to the reader / writer. The conductor part 10 is in a thin sheet shape and is provided on the surface of an insulating base material 11. The conductor part 10 of the present embodiment is circular in shape and is formed by a well-known method such as etching of a metal thin film or pattern printing of aluminum or the like. The coil part 30 is made of a metal thin film continuous from the conductor part 10 and has a substantially C shape by cutting out its center.

[0012] A commercially available product may be used for the RF chip 20. Both ends of the RF chip 20 are bridged between the conductor part 10 and the coil part 30 so as to be electrically connected to both. By electrically connecting the RF chip 20 to the coil part 30, a resonance circuit 60 (FIG. 2(a)) is formed together with the internal capacitance of the RF chip 20. The RF chip 20 operates by generating power using the carrier wave of the reader / writer received by the conductor part 10. Specifically, the RF chip 20 rectifies a part of the carrier wave transmitted from the reader / writer and generates the power supply voltage necessary for operation. The RF chip 20 operates the logic circuit for control and the non-volatile memory storing the unique information of the product, etc. inside the RF chip 20 with the generated power supply voltage, and operates the communication circuit, etc. for transmitting and receiving data with the reader / writer.

[0013] As described above, in the RFID tag 1, the resonance circuit 60 is formed so as to resonate in the frequency band of the received radio wave. This resonance circuit 60 is composed of the coil part 30, the capacitance inside the RF chip 20, and the RF chip 20 as shown in the equivalent circuit diagram of FIG. 2(a). Some RF chips 20 contain capacitors inside, and the RF chip 20 has stray capacitance. Therefore, when setting the resonance frequency of the resonance circuit 60, the capacitance inside the RF chip 20 is taken into consideration. In other words, it is preferable that the resonance circuit 60 has a resonance frequency set in consideration of the inductance of the coil part 30 and the capacitance (capacitance) inside the RF chip 20.

[0014] The resonance frequency f0 [Hz] of this series resonance circuit 60 is given by Equation (1). It is preferable to set the value of the resonance frequency f0 to be approximately the central value of the frequency bandwidth of a plurality of radio waves transmitted from the reader / writer.

Equation

[0015] By considering the capacitance inside the RF chip 20 in this way, the resonant frequency f0 of the resonant circuit 60 can be accurately set within the radio wave frequency band. As a result, the reading performance of the RFID tag 1 can be improved. In addition, the power supply voltage generated by the RF chip 20 can be increased. Furthermore, by adjusting the mounting position of the RF chip 20, the coil section 30 becomes a variable inductor pattern, and the resonant frequency f0 can be adjusted by adjusting L in equation (1). The shape of the coil section 30 can be changed as appropriate.

[0016] As shown in Figure 1, the reed switch 40 is connected by spanning the conductor part 10 and the coil part 30. Various structures of the reed switch 40 are known, but for example, two ferromagnetic leads are sealed in a glass tube at an appropriate distance apart. When a magnetic field is applied from the outside in the axial direction of the leads, the leads are magnetized and the contacts attract each other, making contact and closing the switch. When the external magnetic field is removed, the elasticity of the leads causes the contacts to return to their original position and open the switch. The magnet 50 is a component that magnetizes the reeds and controls the operation of the reed switch 40. By changing the relative distance between the reed switch 40 and the magnet 50, the reed switch 40 is driven to turn the function of the resonant circuit 60 on and off, thereby switching the RFID tag 1 on and off.

[0017] For example, as shown in Figures 3(a) and (b), the RFID tag 1 is covered with an elastic material 70 such as rubber, and the magnet 50 is embedded inside the elastic material 70 to fix it in a position away from the reed switch 40. In Figure 3, the magnet 50 embedded in the elastic material 70 and the reed switch 40 are shown for ease of understanding. When no external force is applied, the resonant circuit 60 is turned on, and the RFID tag 1 operates normally. In other words, it can generate power from the carrier wave from the reader / writer and send and receive data with the reader / writer (RFID tag ON state). To put it another way, if the reader / writer can communicate with the RFID tag 1, it can be determined that the RFID tag 1 is in the ON state.

[0018] As shown in Figure 3(c), when an external force (arrow) is applied to deform the elastic body 70 and the magnet 50 is brought closer to the reed switch 40, the two leads come into contact as described above, closing the circuit, and the conductor part 10 and coil part 30 over which the RF chip 20 is connected are short-circuited. The RF chip 20 can no longer generate power from the carrier wave, the function of the resonant circuit 60 is turned off, and communication between the reader / writer and the RFID tag 1 becomes impossible (RFID tag off state). In other words, if the reader / writer cannot communicate with the RFID tag 1, it can be determined that the RFID tag 1 is in the off state. Figure 2(b) is an equivalent circuit diagram of the resonant circuit 61 of the RFID tag 1 equipped with an elastic body 70. The resonant frequency f0 [Hz] of this series resonant circuit 61 is given by equation (2).

number

[0019] [Second Embodiment] A second embodiment of the RFID tag of the present invention will now be described, but parts that have the same configuration as in the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted. The RFID tag 2 of this embodiment is characterized by having a capacitor section 80. Specifically, as shown in Figures 4(a) and (b), the capacitor section 80 is a long member, with one end of the capacitor 81 connected to the conductor section and the other end connected to a lead wire 82 which acts as a conductor. The lead wire 82 hangs down from the central opening 12 of the RFID tag 2 and functions as a contact point.

[0020] As shown in Figures 4(c) and (d), when the conductive portion 90 of the object to which the RFID tag 2 is attached is inserted into the central opening 12, the capacitor portion 80 comes into contact with the conductive portion 90, so the capacitor portion 80 can function as a capacitor as shown in Figure 5. Although not shown in the illustration, it is assumed that the RFID tag 2 is covered with an elastic material 70 such as rubber, and the magnet 50 is embedded inside the elastic material 70, similar to Figure 3.

[0021] The resonant frequency f0 [Hz] of this resonant circuit 62 is given by equation (3).

number

[0022] By connecting the conductive portion 90 and the conductive portion 10 of the object with the capacitor portion 80, the conductive portion 90 can also function as an antenna. Specifically, a high-pass filter circuit 63 is formed as shown in Figures 5(a) and (b). In this high-pass filter circuit 63, the discharge resistor Rd utilizes the drain resistance component of the semiconductor. By adjusting ω, Ca, and Rd in equation (3), only the high-frequency components of the radio waves can be passed through, thereby removing noise and making it easier to receive the carrier wave from the reader / writer. As shown in Figures 6(a) and (b), a bearing contact 83 made of an annular conductor may be used instead of the lead wire 82. As shown in Figures 6(c) and (d), when the conductive portion is inserted into the opening of the bearing contact 83, the capacitor portion 80 comes into contact with the conductive portion 90, so that the capacitor portion 80 can function as a capacitor.

[0023] [First Embodiment] As an example of the application of the RFID tag of the present invention, a first embodiment of an object action / non-action detection system (hereinafter sometimes simply referred to as the "detection system") will be described. Parts that have the same configuration as in the above embodiment will be denoted by the same reference numerals and their descriptions will be omitted. As shown in Figure 7, the object to which the RFID tag 1 is attached in the detection system 100 is a handle-type valve 101. The handle-type valve 101 includes a main body 102 (fixed part), a handle 103 (movable part) whose relative position to the main body 102 changes, etc. The RFID tag 1 is fixed to the main body with its stem passing through its central opening 12. A pressure plate 104 is attached to the surface of the RFID tag 1, and a height adjustment adapter 105 is attached to the bottom of the RFID tag 1.

[0024] Figure 7(a) shows the valve in the open position, and RFID tag 1 can communicate with the reader / writer (RFID tag ON state). As the valve is closed by turning the handle 103 from the state shown in Figure 7(a), the handle 103 moves downward, and the pressure plate 104 in contact with the handle 103 also moves downward. The elastic body 70, subjected to downward pressure from the pressure plate 104, deforms and contracts, causing the magnet 50 to move closer to the reed switch 40. As shown in Figure 7(b), when the valve is completely closed by turning the handle 103 further, the two leads of the reed switch 40 come into contact due to the approach of the magnet 50, resulting in a closed state, and the RFID tag 1 can no longer communicate with the reader / writer (RFID tag off state). Thus, if the reader / writer can communicate with RFID tag 1, it can be determined that RFID tag 1 is in the ON state and the valve is open (operating). If the reader / writer cannot communicate with RFID tag 1, it can be determined that RFID tag 1 is in the OFF state and the valve is closed (not operating).

[0025] Figure 8 shows a configuration in which multiple valves 101 are connected to piping 106, and RFID tags 3 to 5 are attached to each valve. Each RFID tag 3-5 is equipped with a capacitor section 80 as shown in Figure 4. The adapter is not shown in Figure 8. The capacitor section 80 can function as a capacitor by making contact with the conductive stem 107. In this case, the entire piping functions as an antenna, so the on / off status of each RFID tag 3-5 can be determined at once by simply sending the carrier wave of the reader / writer to a part of the piping.

[0026] [Second Embodiment] A second embodiment of the object action / non-action detection system will now be described, but parts that have the same configuration as in the above embodiment will be denoted by the same reference numerals and their descriptions will be omitted. As shown in Figure 9, in the detection system 200 of the second embodiment, the object to which the RFID tag 1 is attached is a lever-type valve 110. The lever-type valve 110 includes a main body 111 (fixed part), a lever 112 (movable part) whose relative position to the main body changes, etc. Of the RFID tag 1, all parts except the magnet 50 are fixed to the main body 111 with their stems passing through the central opening 12. The magnet 50 is fixed to a bracket 113 that rotates integrally with the lever 112.

[0027] Figures 9(a) and (b) show the valve opened by operating lever 112, and the RFID tag 1 can communicate with the reader / writer (RFID tag ON state). As the lever 112 is turned clockwise from the state shown in Figures 9(a) and (b) to close the valve, the bracket 113 also rotates along with the lever 112. When the valve is completely closed, as shown in Figure 9(c), the magnet 50 is positioned directly above the reed switch 40, and the two leads of the reed switch 40 come into contact, closing the valve, and the RFID tag 1 can no longer communicate with the reader / writer (RFID tag off state). If the reader / writer can communicate with RFID tag 1, it can be determined that RFID tag 1 is in the ON state and the valve is open (operating). If the reader / writer cannot communicate with RFID tag 1, it can be determined that RFID tag 1 is in the OFF state and the valve is closed (not operating).

[0028] [Third Embodiment] A third embodiment of the object action / non-action detection system will now be described, but parts that have the same configuration as in the above embodiment will be denoted by the same reference numerals and their descriptions will be omitted. As shown in Figure 10, in the detection system 300 of the third embodiment, the object to which the RFID tag 1 is attached is the door 120. All parts of the RFID tag 1 except the magnet 50 are fixed to the top of the door frame 122 via a bracket 121. The magnet 50 is fixed to a bracket 124 that rotates integrally with the door body 123.

[0029] Figure 10(b) shows the door body 123 in the open position, and the RFID tag 1 can communicate with the reader / writer (RFID tag ON state). When the door body 123 is closed from the state shown in Figure 10(b), the bracket 124 rotates along with the door body 123. Then, as shown in Figure 10(c), when the door body 123 is completely closed, the magnet 50 is positioned directly below the reed switch 40, causing the two leads of the reed switch 40 to make contact and close, and the RFID tag 1 is unable to communicate with the reader / writer (RFID tag off state). Thus, if the reader / writer can communicate with RFID tag 1, it can be determined that RFID tag 1 is in the ON state and the door is open (operating). If the reader / writer cannot communicate with RFID tag 1, it can be determined that RFID tag 1 is in the OFF state and the door is closed (not operating). Alternatively, the parts of the RFID tag 1 other than the magnet 50 may be fixed to a bracket 124 that rotates integrally with the door body 123, and the magnet 50 may be fixed to the upper part of the door frame 122 via a bracket 121.

[0030] As described above, this detection system can be applied to any object having both fixed and movable parts, and can detect whether an object is functioning or not based on whether or not communication is possible between the reader / writer and the RFID tag. Furthermore, there are no restrictions on the mounting position of the reed switch 40, as long as the function of the resonant circuit 60 can be turned on / off by changing the relative distance between the reed switch 40 and the magnet 50 and driving the reed switch 40. For example, as shown in Figure 11, a part of the coil section 30 may be cut and the reed switch 40 may be strung across it. When the reed switch 40 is open, the coil section 30 is cut, so the resonant circuit 60 does not function, and the RFID tag 1 cannot communicate with the reader / writer (RFID tag off state). When the reed switch 40 is closed, the coil section 30 is connected, so the resonant circuit 60 functions, and the RFID tag 1 can communicate with the reader / writer (RFID tag on state). [Industrial applicability]

[0031] The present invention is an RFID tag with an on / off function and has industrial applicability. [Explanation of Symbols]

[0032] 1-5 RFID tags 10 Conductor section 11 Insulating substrate 12 Central opening 20 RF chips 30 Coil section 40 Reed Switches 50 magnets 60 resonant circuit 61 Resonant circuit 62 Resonant circuit 63 Resonant circuit 70 Elastic body 71 Cavity 80 Capacitor section 81 Capacitors 82 Lead wires 83 Bearing Contacts 90 Conductor part 100 detection systems 101 Handle-type valve 102 Main body 103 Handle 104 Pressure plate 105 adapter 106 Piping 107 Stem 110 Lever-type valve 111 Main body 112 Lever 113 Bracket 120 doors 121 Bracket 122 Door frame 123 Door body 124 brackets 200 detection systems 300 detection systems

Claims

1. It comprises at least an RF chip, a conductor, a coil, a reed switch, and a magnet that controls the drive of the reed switch. The capacitance inside the RF chip and the coil portion form a resonant circuit. The RF chip generates the power necessary for operation from the carrier wave of the reader / writer. An RFID tag with an on / off function, characterized in that the function of the resonant circuit is turned on / off by changing the relative distance between the reed switch and the magnet and driving the reed switch.

2. The RFID tag with an on / off function according to claim 1, characterized in that the on / off function is switched by changing the relative distance between the reed switch and the magnet, thereby driving the reed switch to change whether or not power generation is possible.

3. The RFID tag with on / off function according to claim 1 or 2, wherein an elastic body is provided between the reed switch and the magnet, and the magnet moves toward the reed switch side while deforming the elastic body when an external force is applied, thereby driving the reed switch.

4. The RFID tag with on / off function according to claim 1 or 2, characterized by comprising a capacitor portion connected to the conductor portion.

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