JP2010039896A - Rfid tag and rfid system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the cost of a RFID tag and a RFID system from being increased even when a user is enabled to confirm a reading article with eyes. <P>SOLUTION: The RFID tag 3 is provided with a tag IC chip 6 storing tag information, a tag antenna part 7 electrically connected to the tag IC chip 6 to receive a radio signal outputted from a reader/writer 5 and generate power by the received radio signal, a photoelectric conversion part 20 electrically connected to the tag IC chip 6 to generate power by received light, a received light quantity detecting part 30 for detecting an output corresponding to received light quantity of the photoelectric conversion part 20, and a control part 24 for performing control so as to return a response signal to the reader/writer 5 through the tag antenna part 7 when the output of the photoelectric conversion part 20 detected by the received light quantity detecting part 30 is equal to or more than a predetermined value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an RFID tag and an RFID system that exchange tag information stored and held therein in a non-contact manner.

  In recent years, an RFID (Radio Frequency IDentification) system has been used in order to improve the management of production, distribution, goods, and the like. The RFID system includes an RFID tag and a reader / writer that reads the RFID tag, reads the RFID tag attached to the article, and manages the article.

  The RFID tag includes a tag antenna unit and a tag IC chip. The tag antenna unit receives a radio signal output from the reader / writer, and supplies the tag IC chip with power generated by the tag antenna unit using the received radio signal. Then, the tag IC chip was activated. The RFID tag modulates a part of the radio signal according to the tag information stored and held in the tag IC chip, and returns a response signal to the reader / writer via the tag antenna unit.

  For this reason, when a radio signal is output from the reader / writer, RFID tags of all articles within the communication range are activated, and a response signal of each RFID tag is returned.

Under such circumstances, there has been a demand for making it possible to understand an article to be read by a reader / writer. On the other hand, an RFID system has been proposed in which a read article can be visually recognized. In this conventional RFID system, a sensing light emitting tag that senses light and emits light and an RFID tag are attached to the article, and light is emitted toward the article together with a radio signal from a reader / writer equipped with a light irradiation unit. . As a result, the sensing light emitting tag irradiated with light emits light, so that the user can visually confirm the read article (see, for example, Patent Document 1).
JP 2007-11088 A

  Since the conventional RFID tag uses a light-emitting tag for sensing that emits light by sensing light and the RFID tag, there is a problem that the cost increases.

  Therefore, an object of the present invention is to prevent the cost from increasing even when the user can visually check and read the article.

  In order to achieve this object, an RFID tag of the present invention includes a tag IC chip that stores and holds tag information, and a wireless signal that is electrically connected to the tag IC chip and that receives a radio signal output from a reader / writer. A tag antenna unit that generates electric power by a signal, a photoelectric conversion unit that is electrically connected to the tag IC chip and generates electric power by received light, and a received light amount detection that detects an output corresponding to the received light amount of the photoelectric conversion unit And a control unit that controls the reader / writer to return a response signal via the tag antenna unit when the output of the photoelectric conversion unit detected by the received light amount detection unit is equal to or greater than a predetermined value. And With such a configuration, the initial purpose is achieved.

  Further, the RFID system of the present invention includes the above-described RFID tag and a light irradiation unit that irradiates the RFID tag with light, and the light irradiation unit irradiates the RFID tag with light and reads the tag information of the RFID tag. It is characterized by comprising. With such a configuration, the initial purpose is achieved.

  As described above, the RFID tag of the present invention includes a tag IC chip that stores and holds tag information, and a radio signal that is electrically connected to the tag IC chip and that is output from the reader / writer, and is powered by the received radio signal. A tag antenna unit that generates a power, a photoelectric conversion unit that is electrically connected to the tag IC chip and generates power by the received light, a received light amount detection unit that detects an output according to the received light amount of the photoelectric conversion unit, When the output of the photoelectric conversion unit detected by the received light amount detection unit is greater than or equal to a predetermined value, the reader / writer is provided with a control unit that controls the response signal to be returned via the tag antenna unit. Only the RFID tag that has been made can return a response signal to the reader / writer. For this reason, the read article can be visually confirmed by irradiating light from the reader / writer toward the article to which the RFID tag is attached. As a result, even when the user can visually check the read article, only the RFID tag needs to be attached, and the cost can be prevented from increasing.

  Further, the RFID system of the present invention includes the above-described RFID tag and a light irradiation unit that irradiates the RFID tag with light, and the light irradiation unit irradiates the RFID tag with light and reads the tag information of the RFID tag. Therefore, the user can visually confirm the read article by irradiating light from the reader / writer toward the article to which the RFID tag is attached. As a result, even when the user can visually check the read article, only the RFID tag needs to be attached, and the cost can be prevented from increasing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
First, an RFID system according to an embodiment of the present invention will be described with reference to FIGS. 1 is a schematic configuration diagram of an RFID system 1 according to an embodiment of the present invention, FIG. 2 is a block diagram showing an electrical configuration of the RFID system 1, and FIG. 3 is a photoelectric conversion unit in an RFID tag 3 of the RFID system 1. It is a wave form diagram which shows the example of 20 outputs.

  Here, an example in which an article 2 such as a luggage or a product loaded on a high shelf 40 such as a warehouse is read by the reader / writer 5 from below will be described. Note that it is assumed that there is a distance to the article 2 stacked on the high shelf 40 and is outside the communication range.

  As shown in FIG. 1, the RFID system 1 includes an RFID tag 3 attached to an article 2 and a reader / writer 5 that reads tag information stored and held by the RFID tag 3.

  The reader / writer 5 includes a light irradiation unit 4 that irradiates light to the RFID tag 3. The light irradiation unit 4 irradiates the RFID tag 3 with light and reads tag information of the RFID tag 3.

  It is assumed that the operator reads the RFID tag 3 with the light irradiation unit 4 of the reader / writer 5 directed toward the specific article 2 in order to confirm the contents of the specific article 2 on the high shelf 40. For example, it is assumed that the worker wants to know the contents of the article 2 a out of the two articles 2 on the high shelf 40. In this case, the operator reads the RFID tag 3 with the light irradiation unit 4 of the reader / writer 5 facing the article 2a. The irradiation light 10 irradiated from the light irradiation unit 4 illuminates the article 2a and also the RFID tag 3 attached to the article 2a. Thus, the operator can visually confirm the read article 2a by checking the spot 10a of the irradiation light 10 illuminating the article 2a. Moreover, since the article 2b is not illuminated by the irradiation light 10, it can be seen that the article 2b is not to be read.

  Further, the reader / writer 5 transmits a question signal to the RFID tag 3 via the transmission antenna 8 and receives a response signal from the RFID tag 3 via the reception antenna 9. Thereby, the reader / writer 5 can acquire tag information from the RFID tag 3 attached to the article 2.

  However, the article 2a stacked on the high shelf 40 is outside the communication range of the reader / writer 5 and cannot be read because it is far from the operator's position. Although it is possible to read the reader / writer 5 with stronger radio waves, this also activates many other RFID tags 3 in the warehouse, so that selection takes time and the communication time for communication is long. Become.

  Therefore, the RFID tag 3 according to the present embodiment is electrically connected to the tag IC chip 6 and detects the output corresponding to the amount of light received by the photoelectric conversion unit 20 that generates electric power by the received light. Control so that the response signal is returned to the reader / writer 5 via the tag antenna unit 7 when the output of the received light amount detection unit 30 and the output of the photoelectric conversion unit 20 detected by the received light amount detection unit 30 is equal to or greater than a predetermined value. And a control unit 24. As a result, power can be supplied to the tag IC chip 6 in combination with the power generated by the radio signal received by the tag antenna unit 7, and the reader when the output of the received light amount detection unit 30 is a predetermined value or more. Since the response signal is returned to the writer 5 and the control is performed so that the response signal is not returned to the reader / writer 5 when the output of the received light amount detection unit 30 is smaller than the predetermined value, the output of the received light amount detection unit 30 exceeds the predetermined value. It is possible to respond only when the light to be emitted is irradiated toward the RFID tag 3. That is, the RFID tag 3 irradiated from the light irradiation unit 4 of the reader / writer 5 can return a response signal. Details of the photoelectric conversion unit 20 will be described later.

  Next, the configuration and operation of the RFID system 1 including the RFID tag 3 will be described with reference to FIGS. 2 and 3.

  As shown in FIG. 2, the RFID system 1 includes an RFID tag 3 and a reader / writer 5 that reads tag information of the RFID tag 3.

  The RFID tag 3 is electrically connected to the tag IC chip 6 that stores and holds tag information, and receives a radio signal output from the reader / writer 5 and generates power from the received radio signal. The tag antenna unit 7, the photoelectric conversion unit 20 that is electrically connected to the tag IC chip 6 and generates power by the received light, and the received light amount detection unit 30 that detects an output corresponding to the received light amount of the photoelectric conversion unit 20. And a control unit 24 for controlling the response signal to be returned to the reader / writer 5 via the tag antenna unit 7 when the output of the photoelectric conversion unit 20 detected by the received light amount detection unit 30 is equal to or greater than a predetermined value. ing.

  The RFID tag 3 receives an interrogation signal, which is a radio signal output from the reader / writer 5, at the tag antenna unit 7, generates electric power from the received radio signal, and supplies it to the tag IC chip 6. Further, the RFID tag 3 can generate electric power from the light received by the photoelectric conversion unit 20 and supply it to the tag IC chip 6. The control unit 24 can control to return a response signal to the reader / writer 5 when the output of the photoelectric conversion unit 20 detected by the received light amount detection unit 30 is a predetermined value or more. For example, as shown in FIG. 3, when the tag IC chip 6 is operated by the power supplied to the tag IC chip 6 from the tag antenna unit 7, it is detected by the received light amount detection unit 30 by disturbance light such as a fluorescent lamp. The detection level of the received light amount detection unit 30 is set so that the output of the photoelectric conversion unit 20 is LVa or less. Then, the detection level is set to be equal to or greater than a predetermined value LVb when light is irradiated from the light irradiation unit 4 of the reader / writer 5 to the photoelectric conversion unit 20 at a predetermined distance, for example, a position 5 m away. Note that the detection level may be kept constant and the detection sensitivity adjusted. Accordingly, the RFID tag 3 responds only to the irradiation light 10 of the light irradiation unit 4 while returning the response signal to the reader / writer 5 via the tag antenna unit 7 while preventing the influence of disturbance light such as a fluorescent lamp. be able to.

  3 shows an example in which the output detected by the received light amount detection unit 30 increases as the received light amount at the photoelectric conversion unit 20 increases. If the output detected by the received light amount detection unit 30 decreases as the received light amount at the photoelectric conversion unit 20 increases, the control unit 24 determines that the output detected by the received light amount detection unit 30 is a predetermined value. Control may be performed so that a response signal is returned to the reader / writer 5 via the tag antenna unit 7 at the following times. In any case, when the amount of light received by the photoelectric conversion unit 20 increases to a predetermined value or more, the control unit 24 can control to return a response signal to the reader / writer 5 via the tag antenna unit 7. it can.

  Furthermore, in the photoelectric conversion unit 20, the photodiode 20a and the photodiode 20b, and the photodiode 20c and the photodiode 20d are electrically connected in series so that the output of the photoelectric conversion unit 20 detected by the received light amount detection unit 30 is increased. The series circuit of the photodiode 20a and the photodiode 20b and the series circuit of the photodiode 20c and the photodiode 20d are electrically connected in parallel. Thereby, the RFID tag 3 makes it easy to receive the irradiation light 10 from the light irradiation unit 4.

  The received light amount detection unit 30 detects the received light amount received by the photoelectric conversion unit 20 by detecting the current or voltage flowing through the terminals c and d.

  The reader / writer 5 turns on the light irradiation unit 4 and transmits a question signal to the RFID tag 3 via the transmission antenna 8. The reader / writer 5 receives the response signal from the RFID tag 3 by the receiving antenna 9, demodulates and reads the tag information as will be described later. After reading the tag information, the reader / writer 5 turns off the light irradiation unit 4.

  As described above, in the RFID system 1, the reader / writer 5 turns on the light irradiation unit 4 to irradiate the reading article 2 with light even when it is desired to read the article 2 that is outside the communication range. Thereby, the RFID tag 3 of the article 2 irradiated with light can respond.

  Even when reading a nearby article 2 within the communication range, the output level when the light is irradiated from the light irradiation unit 4 of the reader / writer 5 to the photoelectric conversion unit 20 becomes a predetermined value LVb or more. Since the RFID tag 3 does not respond, the read article 2 a can be visually confirmed by the spot 10 a of the irradiation light 10.

  In this way, the operator can visually confirm the article 2 to be read regardless of whether the article 2 is in a remote place or a close place. The operator can visually confirm the read article 2a by checking the spot 10a of the irradiation light 10 illuminating the article 2.

  Next, the operation of the RFID system 1 will be described. The reader / writer 5 transmits a question signal, which is a radio signal, to the RFID tag 3, receives a response signal from the RFID tag 3, and reads tag information.

  First, the reader / writer 5 turns on the light irradiation unit 4 by the control unit 41 and issues a question command such as “Reply product part number” to the RFID tag 3.

  Next, this question command is superimposed on a predetermined carrier wave by the modulation unit 42 and transmitted as a question signal to the RFID tag 3 via the transmission unit 43 and the transmission antenna 8. As the predetermined carrier wave, a frequency in the UHF band (for example, 952 MHz to 955 MHz) or a microwave band (for example, 2.45 GHz) can be used.

  The RFID tag 3 receives the interrogation signal by the tag antenna unit 7 (tag antennas 7a and 7b) electrically connected to the tag IC chip 6, and rectifies the power generated from the received interrogation signal by the diode 21. A DC voltage is generated. The DC voltage is charged in the capacitor 23 and the DC voltage is supplied to the tag IC chip 6 to activate the tag IC chip 6. As a result, the control unit 24, the demodulation unit 25, the modulation unit 27, and the memory unit 26 of the tag IC chip 6 are activated.

  The RFID tag 3 includes a photoelectric conversion unit 20, and the photoelectric conversion unit 20 is electrically connected to the tag IC chip 6. The photoelectric conversion unit 20 converts the received light into electric power to generate a DC voltage, and the DC voltage is charged to the capacitor 23 via the received light amount detection unit 30 and the diode 22 and supplied to the tag IC chip 6. Thus, the electric power generated by the photoelectric conversion unit 20 is used in combination with the electric power generated by the tag antenna unit 7. The photoelectric conversion unit 20 includes, for example, four photodiodes 20a to 20d that are photoelectric conversion devices, and converts received light into electric power. The DC voltage generated by the photoelectric conversion unit 20 can be supplied to the tag IC chip 6 in combination with the power from the tag antenna unit 7.

  Next, in response to an instruction from the control unit 24, the demodulation unit 25 demodulates the inquiry signal “Respond product number” from the received radio signal.

  In addition, the control unit 24 reads unique identification information (for example, product product number, manufacturing date, manufacturing location, shipping date, etc.) stored and held in the memory unit 26 simultaneously with the instruction to the demodulating unit 25 described above. .

  When the tag information stored in the memory unit 26, that is, the identification information is “product part number A”, the control unit 24 determines that the product part number A is in response to the question. The switch 28 is turned on and off via the switch 27 to respond.

  That is, when the switch 28 is turned on, the terminals a and b of the tag antennas 7a and 7b are short-circuited, and when the switch 28 is turned off, the terminals a and b are opened. Thus, whether or not to reflect the radio wave transmitted from the reader / writer 5 can be controlled according to the tag information, and the contents of the tag information can be transmitted. That is, the switch 28 is turned on or off in correspondence with the tag information “1” and “0”, and a response signal is returned from the tag antenna unit 7 to the reader / writer 5 by the ON / OFF repetition pattern of the switch 28. , "Product part number A" is reported. In the RFID tag 3, a capacitor 29 for matching impedance is connected so that reflection does not occur when the terminals a and b are opened.

  In the reader / writer 5, the response signal received by the reception antenna 9 is transmitted to the demodulation unit 46 via the reception unit 45, and the control unit 41 confirms “product part number A” based on the demodulated signal. The reader / writer 5 stores the information of “product part number A” in the memory unit 49 via the control unit 41, for example. The stored “product part number A” information is output to a management device (not shown) after the work is completed. The management device searches the product information of the product 2 from the database based on the input “product product number A” information, and manages the product inventory, production date, and the like. The display unit and a memory storing the product information may be provided so that the product information can be confirmed at the work place by displaying the product information on the display unit.

  Next, when reading of tag information from the RFID tag 3 is completed, the reader / writer 5 turns off the light irradiation unit 4 by the control unit 41.

  In FIG. 2, the reader / writer 5 includes a clock unit 47 for performing modulation and synchronization, and a power supply unit 48 for supplying a DC voltage to each circuit. The power supply unit 48 is, for example, a battery that generates a DC voltage.

  The reader / writer 5 can also rewrite tag information stored and held in the RFID tag 3 from the outside when the memory unit 26 is rewritable.

  Next, the configuration of the RFID tag 3 will be described with reference to FIGS.

  4 is a plan view of the RFID tag 3 according to the embodiment of the present invention, FIG. 5 is a front view of the RFID tag 3, and FIG. 6 is a partially cutaway perspective view of the RFID tag 3.

  As shown in FIGS. 4 and 5, the RFID tag 3 includes a tag IC chip 6, a tag antenna unit 7 (tag antennas 7 a and 7 b), and photodiodes 20 a to 20 d in a rectangular storage unit 54 described later. Stored. In addition, a rectangular substrate 52 is provided on the metal plate 50 via a metal buffer material 51. Details of the storage section 54 will be described later.

  The metal plate 50 has a reflection effect of reflecting the radio signal and suppresses the influence of the article 2. Thereby, even when the RFID tag 3 is affixed to a plastic bottle filled with a metal container or drinking water, the influence can be eliminated by the metal plate 50, and the antenna characteristics can be stabilized.

  Further, the tag IC chip 6, the photodiodes 20 a to 20 d, and the tag antenna unit 7 are connected through a wiring layer 53 formed on the substrate 52. Since the substrate 52 has both component mounting and light reflection, the surface of the substrate 52 is subjected to gold flash surface treatment. The metal buffer material 51 has a predetermined thickness, and the tag antenna unit 7 is separated from the metal plate 50 by the predetermined thickness. Thereby, deterioration of the antenna characteristics of the tag antenna unit 7 is suppressed.

  In the tag antenna unit 7, the tag antenna 7 a and the tag antenna 7 b are arranged symmetrically on both sides of the tag IC chip 6. The tag antenna unit 7 receives a radio signal, generates power with the tag antenna unit 7 based on the received radio signal, and supplies this power to the tag IC chip 6.

  The photodiode 20a and the photodiode 20b, and the photodiode 20c and the photodiode 20d are separated from each other and electrically connected in series. Thus, the output level of the received light amount detection unit 30 when light is irradiated from the reader / writer 5 to the photoelectric conversion unit 20 is set to be higher than the output level LVa (FIG. 3) due to disturbance light such as a fluorescent lamp. That is, the output level of the received light amount detection unit 30 is set to satisfy LVb> LVa.

  The RFID tag 3 is further provided with one each (photodiode 20a, 20d) in the vicinity of both ends of the substrate 52 and two in the vicinity of the center (photo) in order to easily receive the irradiation light 10 from the light irradiation unit 4. Diodes 20b and 20c) are provided.

  With such a configuration, light can be received simultaneously at different positions and the light receiving area can be increased, so that light can be received effectively. In addition, high output power can be generated stably even with weak light.

  In addition, although the photodiodes 20a to 20d electrically connected in series are further connected in parallel, only the series connection may be used. This also has the same effect. That is, the DC voltage between the terminal c and the terminal d can be increased.

  The photodiodes 20a to 20d may be any photoelectric conversion device that can directly convert light energy into electric power, and a solar cell or an LED (Light Emitting Diode) may be used instead of the photodiode.

  Next, as shown in FIG. 5, the metal buffer material 51 is provided as an insulating material between the metal plate 50 and the substrate 52. As this insulating material, a single layer of a high dielectric constant material or a laminate of different materials is used. Thereby, in the metal shock absorbing material 51, the incident radio wave can be refracted and the distance as a radio wave path can be lengthened. As a result, the thickness of the metal cushioning material 51 can be reduced as compared with the case of insulating with a low dielectric constant material such as paper or a spacer for providing a space. Thereby, the RFID tag 3 can be manufactured thinly.

  Next, the storage unit 54 will be described. As shown in FIG. 6, the accommodating part 54 is comprised, for example with the container, and is provided with the metal plate 50 on the cover upper surface 54a, the cover side surface 54b, and the sticking surface.

  The cover upper surface 54a, which is the front surface, is a surface through which light can be transmitted, and a transparent material is used to apply light to the photodiodes 20a to 20d. For example, a transparent plastic material is used. In order to suppress disturbance light such as a fluorescent lamp other than the irradiation light 10 as much as possible, a hole may be provided in the cover upper surface 54a so that only the photodiodes 20a to 20d are directly exposed to light. Further, a filter that cuts components other than the irradiation light 10 may be provided, and light may be applied to the photodiodes 20a to 20d through this filter.

  The covering side surface 54b is a surface through which light does not easily pass, and an opaque material is used so as not to let the captured light escape. For example, a white plastic material that does not absorb and reflects light is used. Further, the rear surface does not transmit light due to the metal plate 50.

  With such a configuration, the tag IC chip 6, the photodiodes 20 a to 20 d and the tag antenna unit 7 are protected by the storage unit 54, and the light irradiated from the light irradiation unit 4 through the transmission surface of the storage unit 54 is a photodiode. 20a-20d is irradiated. Further, when the front cover upper surface 54a is faced up and attached to the article 2, the light emitted from the light irradiation unit 4 can be received by the photodiodes 20a to 20d through the transmission surface of the storage unit 54, and the rear surface. When the metal plate 50 is mounted on the article 2, the light irradiated from the light irradiation unit 4 is blocked by the storage unit 54, and the light does not reach the photodiodes 20 a to 20 d. This application example will be described later.

  In addition, by making the shape of the accommodating part 54 into a rectangle, while ensuring the space of the optimal length for the tag antenna part 7, the arrangement distance of the photodiodes 20a-20d can be separated. Thereby, while improving the antenna sensitivity of the tag antenna part 7, the photodiodes 20a-20d can receive the irradiation light 10 effectively.

  Next, with reference to FIG. 7, a storage unit 54 that can generate sufficient power with the photodiodes 20 a to 20 d even when weak light is irradiated from the irradiation light 10 will be described. FIG. 7 is an exploded perspective view when the RFID tag 3 according to the embodiment of the present invention is disassembled.

  As shown in FIG. 7, a condenser lens 55 that condenses light is provided on the front surface of the storage portion 54. In order to irradiate the photodiodes 20a to 20d with the light condensed by the condenser lens 55, the condenser lenses 55 are provided in the vicinity of the photodiodes 20a to 20d. In addition, each condensing lens 55 can be efficiently irradiated to the photodiodes 20a to 20d by providing each condensing lens 55 at a position near the center of each of the photodiodes 20a to 20d.

  As described above, in the RFID tag 3, the weak irradiation light 10 can be converted into strong light by each condenser lens 55 to illuminate each of the photodiodes 20 a to 20 d, and the magnitude of the output of the received light amount detection unit 30 can be determined. The control unit 24 can be controlled to return a response signal without erroneous detection.

  As described above, according to the present embodiment, the RFID tag 3 is electrically connected to the tag IC chip 6 and generates electric power by the received light, and the received light amount of the photoelectric conversion unit 20. When the output of the received light amount detection unit 30 that detects an output corresponding to the received light amount and the photoelectric conversion unit 20 detected by the received light amount detection unit 30 is a predetermined value or more, a response signal is sent to the reader / writer 5 via the tag antenna unit 7. A control unit 24 that controls the reader / writer 5 not to send a response signal via the tag antenna unit 7 when the output of the received light amount detection unit 30 is smaller than a predetermined value. Only the RFID tag 3 that has been sent can return a response signal to the reader / writer 5. For this reason, the reading article 2 can be confirmed visually by irradiating light from the reader / writer 5 toward the article 2 to which the RFID tag 3 is attached. As a result, even when the user can visually confirm the read article 2, it is only necessary to attach the RFID tag 3 and the cost can be prevented from increasing.

  The RFID system 1 includes the above-described RFID tag 3 and a light irradiation unit 4 that irradiates the RFID tag 3 with light. The light irradiation unit 4 irradiates the RFID tag 3 with light and tag information of the RFID tag 3. Since the reader / writer 5 is irradiated with light toward the article 2 to which the RFID tag 3 is attached, the read article 2 can be visually confirmed. As a result, even when the user can visually check the read article 2, only the RFID tag 3 needs to be attached, and the cost can be prevented from increasing.

  FIG. 8 is a perspective view showing an application example of the RFID tag 3 in the embodiment of the present invention. In this example, the storage portion 54 of the RFID tag 3 is formed in a sheet shape, the front surface 60a of the storage portion 54 transmits light, and the back surface 60b is colored black or the like so as not to transmit light. Then, the RFID tag 3 is attached to a transparent storage portion 59 that is provided in the article 2 and can be taken in and out. The article 2 that is not desired to be read can be set in an easy-to-understand manner depending on how it is attached to the storage unit 59. That is, when the front surface 60a is faced up and attached to the storage unit 59, the RFID tag 3 attached to the article 2 can be read by irradiating light from the reader / writer 5. On the other hand, when the black back surface 60b is mounted on the storage unit 59, the RFID tag 3 mounted on the article 2 cannot be read even when light is irradiated from the reader / writer 5.

  For example, as shown in FIG. 8, among the articles 2 such as files and valuable boxes such as secret information stored in the shelf 40, the article 2 c is read from the RFID tag 3 by the light from the reader / writer 5. The article 2d cannot read the RFID tag 3 even when the light from the reader / writer 5 is irradiated. In this way, security can be improved by changing the manner in which the storage portion 54 is mounted between the article 2 that is not desired to be read by the RFID tag 3 and the article 2 that may be permitted to be read. That is, when reading is permitted, the front surface 60a of the storage portion 54 is attached to the storage portion 59 with the front side facing up, and when reading is not permitted, the storage portion 54 is turned over and the back surface 60b is attached to the front side. Note that the front surface 60a may be colored yellow or the like that allows light to easily pass through, and the difference in color from the black color of the back surface 60b may be conspicuous to make it easier to understand visually.

  According to the present invention, only the RFID tag that has received light of a predetermined value or more returns a response signal to the reader / writer via the tag antenna unit 7, so that the light from the reader / writer is directed toward the article to which the RFID tag is attached. RFID tags and RFIDs that can prevent the cost from increasing even when the user can visually confirm the read article by irradiating Useful for systems.

1 is a schematic configuration diagram of an RFID system according to an embodiment of the present invention. Block diagram showing the electrical configuration of the RFID system Waveform diagram showing an example of the output of the photoelectric conversion unit in the RFID tag of the RFID system The top view of the RFID tag in embodiment of this invention Front view of the RFID tag Partial cutaway perspective view of the RFID tag Disassembled perspective view when the RFID tag is disassembled A perspective view showing an application example of the RFID tag

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 RFID system 2, 2a, 2b, 2c, 2d Goods 3 RFID tag 4 Light irradiation part 5 Reader / writer 6 Tag IC chip 7 Tag antenna part 7a, 7b Tag antenna 8 Transmission antenna 9 Reception antenna 10 Irradiation light 10a Spot 20 Photoelectric conversion Unit 20a, 20b, 20c, 20d photodiode 21, 22 diode 23, 29 capacitor 28 switch 24, 41 control unit 25, 46 demodulation unit 27, 42 modulation unit 26, 49 memory unit 30 received light amount detection unit 40 shelf 43 transmission unit 45 Receiving Unit 47 Clock Unit 48 Power Supply Unit 50 Metal Plate 51 Metal Buffer Material 52 Substrate 53 Wiring Layers 54 and 59 Storage Unit 54a Covering Top Surface 54b Covering Side Surface 55 Condensing Lens 60a Front Side 60b Back Side

Claims (5)

A tag IC chip for storing and holding tag information;
A tag antenna unit that is electrically connected to the tag IC chip, receives a radio signal output from the reader / writer, and generates power from the received radio signal;
A photoelectric conversion unit that is electrically connected to the tag IC chip and generates electric power from the received light;
A received light amount detector for detecting an output corresponding to the received light amount of the photoelectric conversion unit;
A control unit that controls the reader / writer to send back a response signal via the tag antenna unit when the output of the photoelectric conversion unit detected by the received light amount detection unit is greater than or equal to a predetermined value. A featured RFID tag. The photoelectric conversion unit includes a plurality of photoelectric conversion devices that receive light and generate electric power, and the plurality of photoelectric conversion devices are separated from each other and electrically connected in series. RFID tag described in 1. The tag IC chip, the tag antenna unit, and the photoelectric conversion device,
The RFID tag according to claim 2, wherein the front surface transmits light and the back surface is stored in a storage portion that blocks light. The storage unit arranges a condensing lens for condensing light on the front surface,
The RFID tag according to claim 3, wherein the photoelectric conversion device is irradiated with light condensed by the condenser lens. The RFID tag according to any one of claims 1 to 4,
An RFID system comprising: a light irradiating unit that irradiates light to the RFID tag; and a reader / writer that irradiates the RFID tag with light by the light irradiating unit and reads tag information of the RFID tag. .

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