RFID checker

Abstract

To provide an RFID checker having a simple configuration and capable of easily confirming a radio wave state of a radio wave at a place where an RFID tag is placed.SOLUTION: An RFID checker 100 includes an antenna 10 having a higher gain and directivity than a dipole antenna with respect to a reference radio wave from a reader 160, a rectifier 30 to which a signal detected by the antenna 10 is input, and a display 40 which is turned on when the signal passing through the rectifier 30 is input. As a result, it is possible to easily check the radio wave state at the target location, specifically, the location where the RFID tag TG is disposed, based on the lighting state of the display 40 driven by the power from the antenna 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an RFID checker used to identify the cause of a problem in an RFID (Radio Frequency Identification) system. [Background technology]

[0002] RFID is a technology that generates electromotive force from received radio waves, activates a circuit, and returns the data stored in its own memory. Systems using this technology are used in a variety of places, such as inventory management at logistics centers, process management at factories, book management at libraries, and product management at retail stores. RFID tags are attached to the objects to be managed, and radio waves are transmitted from a reader / writer to read the information on the RFID tag contactlessly, or a display attached to the RFID tag lights up to indicate the location of the managed object.

[0003] When a malfunction occurs in an RFID-based system at a site, it is difficult for on-site workers to determine whether the problem is with the reader / writer (transmitter) or radio wave interference due to the environment, making it difficult for them to respond. When such a problem occurs, workers first check that radio waves are being emitted at an appropriate level from the reader / writer. To check radio wave emissions, a measuring device (spectrum analyzer) is typically used, but it is heavy and expensive to carry to the site. Furthermore, measuring devices are difficult to use and not everyone can do it. For this reason, there is a demand for a portable device at sites where RFID systems are used that can easily check that radio waves are being emitted from the transmitter at an appropriate level and that radio waves are reaching the RFID tag appropriately where it is placed.

[0004] There is a reader / writer testing device that includes a phase synchronization unit that outputs a phase synchronization signal that is phase-synchronized with the reference signal of the reader / writer being tested, a signal generation unit that synchronizes the phase of a pseudo response signal generated by simulating a tag response and an unmodulated continuous wave signal with the phase synchronization signal while maintaining an arbitrary phase difference, and a combination unit that outputs a test signal that combines the pseudo response signal and the unmodulated continuous wave signal (Patent Document 1).This reader / writer testing device is not intended to check the state of radio waves output from the reader / writer, nor is it intended to check the radio wave state at the location where the RFID tag is placed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-198421 Summary of the Invention

[0006] The present invention has been made in consideration of the above-mentioned background art, and aims to provide an RFID checker with a simple configuration that can easily check the radio wave status at the location where an RFID tag is placed.

[0007] In order to achieve the above object, the RFID checker of the present invention comprises an antenna with higher gain and directionality than a dipole antenna for the reference radio waves from the reader, a rectifier to which the signal detected by the antenna is input, and a display that lights up when the signal that has passed through the rectifier is input.

[0008] The RFID checker has a display that lights up when a signal received by the antenna and passed through a rectifier is input, so the radio wave conditions at the target location, specifically the location where the RFID tag is placed, can be easily confirmed based on the lighting state of the display, which is powered by power from the antenna. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a circuit diagram illustrating an RFID checker according to a first embodiment. [Figure 2] 1A is a plan view of an RFID checker, FIG. 1B is a front view of the RFID checker, and FIG. 1C is an external view of an embodiment of the RFID checker. [Figure 3] FIG. 2 is a diagram illustrating an RFID system including the RFID checker of FIG. [Figure 4] FIG. 10 is a circuit diagram illustrating an RFID checker according to a second embodiment. [Figure 5] FIG. 10 is a circuit diagram illustrating a modified RFID checker. DETAILED DESCRIPTION OF THE INVENTION

[0010] [First embodiment] Hereinafter, an RFID checker according to a first embodiment of the present invention will be described with reference to FIG.

[0011] The RFID checker 100 comprises an antenna 10 with higher gain and directionality than a dipole antenna, a matching circuit 20 that efficiently transmits a signal detected by the antenna 10 to the next stage, a rectifier 30 to which the signal detected by the antenna 10 and passed through the matching circuit 20 is input, and a display 40 that lights up when the signal passed through the rectifier 30 is input. The antenna 10, matching circuit 20, rectifier 30, and display 40 are connected in series. In the illustrated RFID checker 100, power is obtained by rectifying radio waves, and no battery is required.

[0012] The antenna 10 is specifically a Yagi antenna 11, and is intended to detect radio waves of, for example, 920 MHz, but is not limited to this. The radio waves that the antenna 10 targets are those transmitted by a reader (not shown) in the RFID frequency band, and are referred to as reference radio waves in this specification.

[0013] Referring to FIGS. 2A and 2B, the antenna 10 is formed on an insulating substrate 12 and includes main bodies 11a and 11b, a director 11c, and a reflector 11d. The main bodies 11a and 11b are similar to those of a dipole antenna, and a circuit unit 100a is attached and electrically connected to the main bodies 11a and 11b above a power supply area GA between the inner terminals. The main bodies 11a and 11b, the director 11c, and the reflector 11d are conductors in the form of wiring patterns, and are formed, for example, by forming a mask pattern on a thin copper layer uniformly formed on the insulating substrate 12, removing the copper layer by etching, and then removing the mask pattern. For example, copper wires or copper foils corresponding to the main bodies 11a and 11b, the director 11c, and the reflector 11d may be attached to the insulating substrate 12 using an adhesive. The main body 11b is grounded on the power supply area GA side.

[0014] By using the antenna 10 described above, it is possible to give the antenna 10 directionality, making it possible to determine the direction in which radio waves are coming. Direction markings 14 consisting of arrows that correspond to the direction in which the radio waves are coming (i.e., the direction in which the radio waves are propagating) are printed on the insulating substrate 12. The reverse direction of the direction markings 14, i.e., the direction opposite to the arrow, indicates the direction in which the radio wave source or reflecting surface is located.

[0015] The circuit unit 100a associated with the antenna 10 includes a matching circuit 20, a rectifier 30, and a display 40. That is, the RFID checker 100 is integrally formed on an insulating substrate 12 and has the appearance of a rectangular plate as a whole, but the external shape of the RFID checker 100 is not limited to a rectangle and can be various shapes including, for example, an ellipse or a polygon.

[0016] Returning to FIG. 1, the matching circuit 20 arranged between the antenna 10 and the rectifier 30 is intended to enhance reception sensitivity and is composed only of a coil 21. In other words, the matching circuit 20 is a general matching circuit without the capacitor, but it has been confirmed that it functions adequately as a matching circuit. In this way, the matching circuit 20 has a simple configuration that eliminates unnecessary components. However, the matching circuit 20 may also be one that includes a capacitor, as in a general matching circuit.

[0017] The rectifier 30 is composed of a diode 31 connected in parallel with the output of the matching circuit 20 and a diode 32 connected in series. The input terminal is between the diodes 31 and 32, and the cathode of the series-connected diode 32 is the output terminal. The rectifier 30 is a voltage-doubler rectifier circuit that doubles the output voltage. The rectifier 30 is an application of the Cockcroft-Walton circuit, but without the capacitor. It has been confirmed that the rectifier 30 functions adequately as a voltage-doubler rectifier circuit, despite the absence of the capacitor. In this way, the rectifier 30 has a simple configuration that eliminates unnecessary components. However, the rectifier 30 may also be equipped with a capacitor, as in a conventional Cockcroft-Walton circuit.

[0018] The display 40 is a low-current or low-current consumption LED (Light Emitting Diode) 41. In this specification, a low-current consumption LED 41 means one that emits light at a specified level of luminous intensity even at 10 mA or less. In this specific example, an LED 41 that emits yellow light at 1 mA is used. For the low-current consumption LED 41, for example, an AlGaInP-based element can be used to easily achieve a low current. If the signal converted to DC by the rectifier 30 has sufficient intensity, it can light up the LED 41 with sufficient brightness.

[0019] When radio waves arrive in the RFID checker 100 from a reader (not shown), the antenna 10 extracts a current of a frequency corresponding to the incoming radio waves, and this current signal is input to the rectifier 30 via the matching circuit 20. The signal that passes through the rectifier 30 is smoothed and amplified to twice the voltage. The display 40, connected to the output of the rectifier 30, emits light if the incoming radio waves are at or above a predetermined strength, and the brightness or luminance of the display 40 increases accordingly as the radio wave strength increases. In other words, by adjusting the orientation of the RFID checker 100 and observing the display 40, it is possible to check the main direction from which radio waves are coming and the radio wave strength from that direction.

[0020] FIG. 2(C) shows the appearance of a specific embodiment. (1) The RFID checker 100 of the embodiment does not require a battery, so there is no need to worry about the remaining battery power. (2) The RFID checker 100 of the embodiment has a sensing distance of approximately 150 cm, making it highly practical. (3) The RFID checker 100 of the embodiment employs a directional antenna 10, and by changing the direction of the antenna 10, the effects of reflected waves and the direction of radio waves can be checked. (4) The RFID checker 100 of the embodiment is very inexpensive because it has a small number of parts. It does not require a power switch and operates simply by pointing it in the direction of the radio waves, making it easy to use even without specialized knowledge. As such, the RFID checker 100 of the embodiment can be manufactured very inexpensively and is easy to use, so it can be widely distributed to many stakeholders, not just field workers but also sales staff, etc.

[0021] As a comparative example, a device with a dipole antenna connected to a receiving circuit including an amplifier and illuminating an LED when receiving radio waves is considered. With such conventional RFID checkers, it is difficult to identify the direction of radio waves, and the receiving circuit is expensive. Furthermore, such conventional RFID checkers are available in both battery-powered and non-battery-based models. Battery-powered checkers require a power switch to avoid concerns about battery life. Battery-free checkers eliminate the need to worry about battery life and are easy to manage, but their sensing distance is extremely short, at around 10 cm, making them impractical. Another type of device is called an LED tag, which lights up when placed within the detection range of a reader. This type of LED tag does not light up simply by receiving radio waves from the reader; it requires a command to be received, and determining the direction of the radio waves is difficult.

[0022] 3 is a conceptual diagram illustrating how to use the RFID checker 100. The test subject of the RFID checker 100 is the reader / writer 60 or the reader 160. The combination of the reader / writer 60 or the reader 160 and the RFID tag TG is called an RFID system 200.

[0023] The reader / writer 60 has an RFID antenna 61 and a control drive circuit 62, and the control drive circuit 62 includes a CPU 62a and a memory 62b. The control drive circuit 62 supplies power to the RFID antenna 61, causes it to output radio waves in a predetermined band (specifically, for example, radio waves in the UHF band of 920 MHz), receives response waves from an RFID tag TG present in front of the reader / writer 60, identifies the RFID tag TG, obtains necessary information from the RFID tag TG, and writes information to the RFID tag TG as necessary.

[0024] The RFID checker 100 can be used to diagnose problems with the reader-writer 60 or the RFID system 200. The RFID checker 100 is pointed toward the reader-writer 60, as shown by the solid line, to check the frontal radio waves EW0 output from the reader-writer 60. If the frontal radio waves EW0 output from the reader-writer 60 are strong enough, the indicator 40 of the RFID checker 100 lights up brightly. If the frontal radio waves EW0 output from the reader-writer 60 are not strong enough, the indicator 40 does not light up or lights up faintly but darker than normal. To detect the reflected component EW2 from the wall WA, the RFID checker 100 is pointed toward the wall WA, not toward the reader-writer 60, as shown by the dotted line. In this case, if the reflected component EW2 is strong enough, the indicator 40 lights up. In this case, interference between the frontal radio waves EW0 and the reflected component EW2 becomes a problem. If the reflected component EW2 is weak, the indicator 40 does not light up or lights up faintly but darkly. In this case, it can be seen that the interference caused by the reflected component EW2 is at a level that does not cause any problems.

[0025] The reflected component EW2 of the radio waves from the reader / writer 60 occurs not only from the wall WA, but also from reflections on the floor, ceiling, and surrounding objects. If directivity is ignored, the reflected component EW2 can significantly reduce the strength of the radio waves in some locations. This is because the direct wave (frontal radio wave EW0) arriving directly from the reader / writer 60 and the reflected wave (reflected component EW2) interfere with each other, weakening the strength of the radio waves in locations where the phases of the two radio waves are opposite. However, if the RFID checker 100 can determine the situation and direction of the reflected wave (reflected component EW2), it becomes possible to take measures to counter the reflection, such as attaching a radio wave absorber.

[0026] The RFID checker 100 of the first embodiment described above comprises an antenna 10 that has higher gain and directionality than a dipole antenna with respect to the reference radio waves from the reader 160, a rectifier 30 to which the signal detected by the antenna 10 is input, and a display 40 that lights up when the signal that has passed through the rectifier 30 is input.

[0027] The RFID checker 100 has a display 40 that lights up when a signal received by the antenna 10 and passed through the rectifier 30 is input. Therefore, the radio wave conditions at the target location, specifically the location where the RFID tag TG is placed, can be easily confirmed based on the lighting state of the display 40, which is powered by power from the antenna 10, and maintenance related to the power supply, etc. is not required.

[0028] [Second embodiment] The RFID checker of the second embodiment will be described below. The RFID checker of the second embodiment is a partial modification of the RFID checker of the first embodiment, and the same parts are designated by the same reference numerals and redundant explanations will be omitted.

[0029] 4 is a circuit diagram illustrating an RFID checker 100 according to a second embodiment. In this case, the RFID checker 100 includes a three-stage Cockcroft-Walton circuit, in which three diodes D1, D2, and D3 and three capacitors C1, C2, and C3 are connected in a stepped manner, as a rectifier 1030. In this case, the rectifier 1030 is a triple voltage rectifier circuit, which triples the output voltage of the matching circuit 20.

[0030] 5 is a circuit diagram illustrating a modified RFID checker 100. In this case, the RFID checker 100 includes a four-stage Cockcroft-Walton circuit in which four diodes D1, D2, D3, and D4 and four capacitors C1, C2, C3, and C4 are connected in a stepped manner as a rectifier 2030. In this case, the rectifier 2030 is a quadruple voltage rectifier circuit that quadruples the output voltage of the matching circuit 20.

[0031] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments.

[0032] Antenna 10 may be any antenna superior in gain and directivity to a dipole antenna, and for example, director 11c or reflector 11d may be omitted. Alternatively, the number of directors 11c constituting antenna 10 may be increased within the allowable range of size increase.

[0033] For example, the rectifier 30 may amplify the voltage by five times or more when rectifying the output from the matching circuit 20 .

[0034] The direction mark 14 formed on the insulating substrate 12 of the antenna 10 is not limited to an arrow, and various symbols that can specify the direction can be used. A protrusion may be formed on the outer periphery of the insulating substrate 12. [Explanation of symbols]

[0035] 10...antenna, 11...Yagi antenna, 11a, 11b...main body, 11c...director, 11d...reflector, 12...insulating substrate, 14...arrow, 20...matching circuit, 21...coil, 30, 1030, 2030...rectifier, 31, 32...diode, 40...display, 41...LED, 60...reader / writer, 61...RFID antenna, 62...control drive circuit, 62a...CPU, 62b...memory, 100...RFID checker, 100a...circuit unit, 160...reader, 200...RFID system, C1, C2, C3, C4...capacitor, D1, D2, D3, D4...diode, EW0...front radio wave, EW2...reflected component, GA...power supply area, TG...RFID tag, WA...wall

Claims

1. For the reference radio wave from the reader, an antenna with higher gain and directivity than a dipole antenna, a rectifier to which the signal detected by the antenna is input; a display that lights up when a signal that has passed through the rectifier is input; An RFID checker comprising:

2. The antenna is a Yagi antenna. The RFID checker according to claim 1 .

3. The rectifier is a voltage doubler rectifier circuit. The RFID checker according to claim 1 .

4. a matching circuit is inserted between the antenna and the rectifier; The RFID checker according to claim 1 .

5. The indicator is a low current LED. The RFID checker according to claim 1 .

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