WO2018108224A1

WO2018108224A1 - Rfid tag

Info

Publication number: WO2018108224A1
Application number: PCT/DK2017/050440
Authority: WO
Inventors: Thomas Probst
Original assignee: Cgi Danmark A/S
Priority date: 2016-12-16
Filing date: 2017-12-18
Publication date: 2018-06-21

Abstract

The invention provides An RFID tag comprising : a radio frequency (RF) analog interface circuit for communicating with an external reader via an analog interface antenna; digital memory; digital controller connected to the analog interface to receive electrical power therefrom and to exchange data signals with the analog interface, including data signals received via the antenna and data signals to be transmitted by the antenna, the digital controller furthermore being connected to the digital memory to read data therefrom; tamper conductor element electrically connected to the analog interface and being able to assume an intact state in which the tamper conductor element is able to conduct an electric current and to assume a broken state in which the tamper conductor element is not able to conduct an electric current; logic circuit connected to the tamper conductor element and configured to provide, when the RFID tag is powered by electrical power, a first control signal to the digital controller if the tamper conductor element is in the intact state and a second control signal different from the first control signal if the tamper conductor element is in the broken state; the digital controller further being configured to provide a first data output signal to the analog interface if the electronic logic circuit provides the first control signal, and to provide a second data output signal different from the first data output signal if the electronic logic circuit provides the second control signal.

Description

RFID tag

Technical field

The present invention relates to RFID tags. Background of the invention In various contexts, it is desirable to be able to determine whether a physical item has been handled, or handled in a certain way. Advertisers that mail advertisements to potential consumers are generally interested in creating as much sales as possible for the least amount of mailed advertisements. Mailing advertisements to individuals who are unlikely to purchase the product being advertised is undesirable. Another problem, one faced by many companies, is that when payment reminders are sent to late payers, surprisingly often the late payers claim to not have received the payment reminder. This is currently impossible to prove. Having an indication that the payment reminder has been opened would be very valuable for companies facing this common problem. US patent application publication US 2006/214789 Al discloses a sensor may be used to detect a previous or current change of state, and the change may be reported by a radio frequency identification (RFID) tag. In some embodiments, the change may represent a broken security seal, which in turn may affect an electrical connection that can be sensed by the RFID tag during operation of the RFID tag. However, the features specified in the claims are not disclosed. Additionally, it does not provide any motivation for the person skilled in the art to provide the embodiments described in the attached claims, whether the document is considered alone or in combination with other documents.

US patent application publication US 2006/214789 Al discloses one or more switches that may be coupled to a radio frequency identification (RFID) tag, so that the response of the RFID tag indicates the state of the switch(es). The RFID tag and the switch(es) may be coupled together in various ways so that the state of the switches affects the response of the RFID tag to an RFID reader. It fails to disclose any of the embodiments described in the attached claims. Additionally, it does not provide any motivation for the person skilled in the art to provide the embodiments described in the attached claims, whether the document is considered alone or in combination with other documents. International patent application publication WO 2006/002667 Al relates to blister packaging ( 100) comprising a film or foil ( 104) for sealing a blister (102) of said packaging ( 100). The film or foil ( 104) comprises an electrically conductive region ( 106). The blister packaging ( 100) also comprises a monitoring unit ( 108), which is configured to display, independently of an electrical characteristic of the conductive region ( 106), whether the blister (102) is sealed or has been opened. It fails to disclose any of the embodiments described in the attached claims. Additionally, it does not provide any motivation for the person skilled in the art to provide the embodiments described in the attached claims, whether the document is considered alone or in combination with other documents. German patent application publication DE102011050196 relates to an apparatus for detecting a manipulation of at least one of several present in a container products using an existing in or on the container or on its packaging a memory having content RFID transponder. The aim of the invention is to check equipped with RFID label containers as to whether they are complete. It fails to disclose any of the embodiments described in the attached claims. Additionally, it does not provide any motivation for the person skilled in the art to provide the embodiments described in the attached claims, whether the document is considered alone or in combination with other documents.

US patent application publication US 2005/184871 Al relates to packaging, e.g. an envelope or a parcel, that can be checked for tampering, which packaging includes a hermetically sealed body, the body being formed by folding a sheet of material that has been cut to a predefined shape. It fails to disclose any of the embodiments described in the attached claims. Additionally, it does not provide any motivation for the person skilled in the art to provide the embodiments described in the attached claims, whether the document is considered alone or in combination with other documents

Summary of the invention

The present invention provides an RFID (radio frequency identification) tag for use in attempts to address the issues described above. In a first aspect, the invention provides an RFID tag comprising : - a radio frequency (RF) analog interface circuit for communicating with an external reader via an analog interface antenna and for providing electrical power, a digital memory, a digital controller connected to the analog interface to receive electrical power therefrom and to exchange data signals with the analog interface, including data signals received via the antenna and data signals to be transmitted by the antenna, the digital controller furthermore being connected to the digital memory to read data therefrom, a tamper conductor element electrically connected to the analog interface and being able to assume an intact state in which the tamper conductor element is able to conduct an electric current and to assume a broken state in which the tamper conductor element is not able to conduct an electric current, - an electronic logic circuit connected to the tamper conductor element and configured to provide, when the RFID tag is powered by electrical power, a first control signal to the digital controller if the tamper conductor element is in the intact state and a second control signal different from the first control signal if the tamper conductor element is in the broken state, the digital controller further being configured to provide a first data output signal to the analog interface if the electronic logic circuit provides the first control signal, and to provide a second data output signal different from the first data output signal if the electronic logic circuit provides the second control signal.

It is well known that "RFID" generally covers a range of different technologies all of which involve identification via radio frequency signals. Different RFID technologies use different RF frequencies and have different physical ranges.

In some embodiments, the digital controller is configured to respond to receiving the first control signal by reading a first identification information from the digital memory and provide a first data output signal representing the first identification information, the digital controller further being configured to respond to receiving the second control signa l by reading a second identification information from the digital memory and provide a second data output signal representing the second identification information.

In some embodiments, the digital controller is configured to respond to receiving the first control signal by reading a first identification information from the digital memory and provide a first data output signal representing the first identification information and comprising an indication that the digital controller has received the first control signal from the electronic logic circuit, the digital controller further being configured to respond to receiving the second control signal by reading the first identification information from the digital memory and provide a second data output signal representing the first identification information and comprising an indication that the digital controller has received the second control signal from the electronic logic circuit.

In some embodiments, the digital controller is configured to respond to receiving the second control signal by writing a broken state indication to a state memory section of the memory to indicate that the tamper conductor element is in the broken state, the digital controller further being configured to respond to receiving either of the first control signal and the second control signal by reading a content of the state memory section and reading a first identification information from the memory and providing a data output signal representing the first identification information and representing the content of the state memory section.

In some embodiments, the tamper conductor element is at least partly exposed on a surface of the RFID tag.

In some embodiments, the RFID tag comprises a plurality of tamper conductor elements, and the digital controller is configured to provide second data output signals identifying tamper conductor elements that are in the broken state.

In some embodiments, the electronic logic circuit is a digital logic capable of providing a high state and a low state in dependence on whether the tamper conductor element is in the intact state or in the broken state.

In a second aspect, the invention provides an item comprising an RFID tag in accordance with embodiments of the first aspect of the invention . An RFID tag is attached to the item at a first contact point of the item and at a second contact point of the item, the first contact point of the item being attached to the tamper conductor element in such a way that when the item is modified in such a way that the first contact point and the second contact point exceeds a critical distance characteristic of the RFID tag, the second contact point of the item will remain attached to the RFID tag while the tamper conductor element will break, thereby assuming the broken state. In some embodiments, the item has a fold between two item parts and the RFID tag attaches the two item parts to one another. In some embodiments, the item comprises at least one of: a folded card, a folded advertisement, an envelope.

Brief descriptions of the drawings

Figure 1 schematically illustrates a prior-art RFID tag. Figure 2 schematically illustrates an RFID tag in accordance with an embodiment of the invention.

Figure 3 schematically illustrates an embodiment of the invention that uses a single tag ID.

Figure 4 illustrates steps performed in the RFID tag shown in Figure 3.

Figure 5 schematically illustrates an embodiment of the invention that uses two distinct tag IDs.

Figure 6 illustrates steps performed in the RFID tag shown in Figure 5.

Figure 7 schematically illustrates an embodiment of an electronic logic circuit used in selected embodiments of the invention.

Figure 8 schematically illustrates an embodiment of the invention that uses a tag ID and a status indication.

Figure 9 illustrates steps performed in the RFID tag shown in Figure 8.

Figure 10 schematically illustrates an embodiment of the invention that uses a plurality of tamper conductor elements, all in the intact state.

Figure 11 schematically illustrates an embodiment of the invention that uses a plurality of tamper conductor elements being in different intact/broken states.

Figure 12 schematically illustrates an envelope fitted with an embodiment of the RFID tag where the envelope has not yet been closed.

Figure 13 schematically illustrates the envelope from Figure 12, now in a closed condition .

Figure 14 schematically illustrates two parts of the envelope in Figure 12 and 13 held together by an embodiment of the RFID tag. The RFID tag tamper conductor element an initial condition where the conductor is in the intact state. Figure 15 schematically illustrates two parts shown in Figure 14, now brought apart beyond a critical distance, causing the tamper conductor element to break, whereby it is in the broken state.

Detailed description of selected embodiments

In the following, selected embodiments of the present invention will be described with reference to the drawings.

Fig. 1 illustrates a prior-art RFID circuit like the one described in the product data sheet SL3S1203_1213 - UCODE G2il_ and G2il_+ from NXP Semiconductor. It comprises an analog interface, a digital controller and a digital memory. The analog interface is responsible for providing a stable supply voltage. It is also responsible for demodulating data received from an external reader. The analog interface also has a modulator for transmitting data back to the external reader. An antenna is used to improve the transmit and receive sensitivity of the RFID circuit. As will be described below, the reader can also cause the RFID tag to effect changes in a memory inside the RFID tag.

The RFID circuit also has a digital controller in communication with the analog interface. As described in the product data sheet, the digital controller includes state machines, processes the RF identity protocol and handles communication with the memory.

Further details may be found in the product data sheet. Fig. 2 illustrates an RFID tag in accordance with an embodiment of the invention . It is similar to the RFID circuit illustrated in Fig. 1, but differs in a number of essential ways.

The RFID tag 200 in Fig. 2 comprises, similarly to Fig. 1, an analog RF interface 201 comprising a voltage regulator 221, a demodulator 223, a modulator 225, pads 231 for connection to the internal electronics of the RFID tag and to an antenna 209, and a rectifier 229. It also comprises a digital controller 203 which, in this example, provides for anti - collision, read/write control to memory, access control, EEPROM memory control, and RF interface control. Furthermore, it comprises a memory 205 for storing RFID tag data 240, such as a tag ID 241. The analog interface also provides power for the RFID tag, either harvested from the electric field on an external reader/interrogator (passive RFID tag) or provided by a built-in power source (active RFID tag). As opposed to prior-art RFID tags, the RFID tag 200 in Fig. 2 also comprises an electronic logic circuit 213 and a tamper conductor element 211. In Fig. 2, the tamper conductor element is illustrated as being connected to a set of two pads 231 dedicated specifically to that purpose. These electronic logic circuit 213 and the tamper conductor element 211 are connected, and the electronic logic circuit will provide an output that depends on the state of the tamper conductor element. An example of an electronic logic circuit for use in the present invention is provided later in this specification . An output of the electronic logic circuit is connected to the digital controller 203. The tamper conductor element 211 is electrically connected to analog interface pads 231 and is able to assume 1) an intact state in which the tamper conductor element is able to conduct an electric current, and 2) a broken state in which the tamper conductor element is not able to conduct an electric current.

Another difference from prior-art RFIDs is that the digital controller is responsive to different input signals from the electronic logic circuit. This is described in detail below. Fig. 3 illustrates the RFID tag 200 but in a condition where the tamper conductor element is in the broken state 212, which means that the tamper conductor element is unable to conduct a current.

In Fig. 2 and 3, the memory 205 stores a tag ID 241 which can be read by the digital controller. When the tamper conductor is in the intact state, the electronic logic circuit provides either a high or a low state signal. If the tamper conductor element is in the broken state, the electronic logic circuit will provide the opposite state signal, i.e. low or high, respectively.

Fig. 4 illustrates how the digital controller in particular may operate for the RFID tag configuration shown in Fig. 2 and 3. In the present embodiment, the digital controller, when the RFID tag is interrogated by an external reader, receives a control signal (step 401) from the analog interface. In response, the digital controller obtains the tag ID 241 (shown in Fig. 2 and 3) from the memory 205, as shown in step 403. The digital controller then constructs a data output signal the content of which depends on the control signal received in step 401. Then, or in conjunction with constructing the data output signal, step 405, the digital controller provides, illustrated by step 407, the data output signal to the analog interface. The analog interface transmits a representation of the data output signal, which can then be read by the external reader. Fig. 5 illustrates another embodiment of the RFID tag. In this case, the memory stores two different tag IDs, "tag ID 1" 243 and "tag ID 2" 242. In this embodiment, the digital controller is configured differently, as illustrated partly by Fig. 6. In the present

embodiment, the digital controller, when the RFID tag is interrogated by an external reader, receives a control signal (step 601) from the analog interface, just as described in relation to the embodiment in Figs. 2 and 3. In response, the digital controller now reads a tag ID, step 603, in dependence on the control signal received. As an example, a high control signal may cause the digital controller to provide a data output signal representing "tag ID 1" 243. If the control signal is a low control signal, the digital controller would instead provide a data output signal representing "tag ID 2" 242, in step 605. This allows for not only obtaining a unique ID, but also for determining the state of the tamper conductor element, intact or broken.

Fig. 7 illustrates an example of an electronic logic circuit for an embodiment of the invention . When the tamper conductor is in the intact state, the input of the electronic logic circuit gate 722 is at ground, whereby the electronic logic circuit provides a control signal which is a "low" at output 701. If the tamper conductor element is torn, the input of the electronic logic circuit gate is not pulled to ground. Instead, a pull-up resistor 721 will cause the control signal from the output 701 of the gate to be a "high" at nearly v_DD.

As already described, the digital controller 203 is connected to the output of the logic circuit 213. Depending on whether the digital controller receives a "low" or a "high", it will return different data output signals for the analog interface to be transmitted to the reader.

Fig. 8 illustrates another embodiment of the RFID tag. The RFID tag comprises a tag ID in its TID memory, EPC memory or user memory. In the present embodiment, the digital controller sends specific memory content on its data output, including memory 250 assigned for storing the state of the tamper conductor element. Before the tamper conductor element is broken, the memory 250 assigned to storing the tamper conductor element state is in a first state. As an example, a specific bit in the user memory is set to 0 before the conductor is broken . When the conductor is broken, the digital controller writes a 1 in place of the 0 in the user memory assigned. The digital controller in this embodiment always outputs the tag ID and the content of the bit, thereby indicating the state of the tamper conductor element. Again, this allows a reader to determine whether the conductor is intact or not by analyzing the state bit, and at the same time obtain the taq ID stored in the RFID tag. Fig. 9 illustrates some of the steps for the embodiment in Fig. 8. When the digital controller receives the second control signal from the analog interface, step 901. This indicates that the electronic conductor element is now in a broken state. In response, in step 903, the digital controller causes the alteration of the memory described in relation to Fig. 8. When the RFID tag is interrogated, it will read the status (step 905) from the memory 205 and return, in step 907 a corresponding data output signal to the analog interface 201.

Fig. 10 illustrates an embodiment of the RFID tag that uses a plurality of tamper conductor elements 211, 215, 217, all in the intact state. In that case, the digital control (not shown) is configured to handle multiple electronic conductor elements. Fig. 11 illustrates that two of the three electronic conductor element have been broken, 212, 218. The digital controller will return data output signals revealing the statuses.

Fig. 12 illustrates the use of the RFID tag described above in an envelope 1200. The envelope has a back side 1201 that together with a front part (not shown) forms an inside space 1203 for a letter (not shown). The envelope furthermore has a flap 1205, which, in order to close the envelope, is folded onto the back side 1201. Adhesive on the flap 1205 and/or on the back side 1201 ensures that the envelope remains closed.

An RFID tag 200 is attached to the flap 1205, for instance via an adhesive surface on the RFID tag. On the opposite side of the RFID tag, the electronic conductor element is exposed. It may comprise a sticky surface, or a glue may be added, whereby when envelope is closed by folding down the flap 1205, as illustrated by the arrow in fig. 12, the adhesive conductor will stick to a letter in the inside space 1203 or to an inside of the envelope. This is illustrated in Fig. 13.

If the RFID tag is read at this point, it will provide the first data output signal corresponding to the intact conductor. To read the letter, it is necessary to remove the letter from the envelope. If the flap 1205 is pulled from the back side 1201, the tamper conductor element of the RFID tag will break. If the RFID tag is read, it will provide the second data output signal signifying a broken conductor.

A recycling bin having an RFID tag reader will be able to log whether the letter has been opened or not. Collecting this information allows the sender to determine whether the letter has been read or not, and appropriate action may be taken depending on the result obtained by the reader.

Fig. 14 illustrates the mechanism in more detail. An RFID tag 200 with a sticky tamper conductor element 211 and an adhesive layer 1410 ensure that parts 1401 and 1402 of e.g a folded item are held together. A distance di between the two parts leaves the RFID tag intact. However, when the parts are separated by a distance, d, higher than a critical distance dc as shown in Fig. 15, the tamper conductor element breaks. An RFID tag reader will now, when interrogating the RFID tag, receive the second data outp ut signal and therefore find that the RFID tag has been tampered with .

Whichever principle is applied, the analog interface subsequently transmits the data output signal from the digital controller to the reader, whereby it is possible to infer both a tag ID and the state of the tamper conductor element.

The description above is merely to illustrate the inventive concepts of the present invention Although a number of different ways of providing data output signals representing both a tag ID and a state of the tamper conductor element has been provided, there are many other ways in which this can be realized. The scope of protection is not limited to the examples provided herein, but is instead determined by the extent afforded the claims in accordance with the jurisdiction in question. The I/O control element shown in Fig. 1 is not included in the other figures for simplicity. It does not imply that embodiments of the RFID tag in accordance with the present invention do not comprise I/O control means.

Claims

1. An RFID tag (200) comprising :

a radio frequency (RF) analog interface circuit (201) for communicating with an external reader via an analog interface antenna (209) and for providing electrical power,

a digital memory (205),

a digital controller (203) connected to the analog interface to receive electrical power therefrom and to exchange data signals with the analog interface, including data signals received via the antenna and data signals to be transmitted by the antenna, the digital controller furthermore being connected to the digital memory to read data therefrom,

a tamper conductor element (211) electrically connected to the analog interface and being able to assume an intact state (211) in which the tamper conductor element is able to conduct an electric current and to assume a broken state (212) in which the tamper conductor element is not able to conduct an electric current,

an electronic logic circuit (213) connected to the tamper conductor element and configured to provide, when the RFID tag is powered by electrical power, a first control signal to the digital controller if the tamper conductor element is in the intact state and a second control signal different from the first control signal if the tamper conductor element is in the broken state, the digital controller further being configured to provide a first data output signal to the analog interface if the electronic logic circuit provides the first control signal, and to provide a second data output signal different from the first data output signal if the electronic logic circuit provides the second control signal, and wherein the digital controller is:

i) configured to respond to receiving the first control signal by reading a first

identification information (243) from the digital memory and provide a first data output signal representing the first identification information, the digital controller further being configured to respond to receiving the second control signal by reading a second identification information (242) from the digital memory and provide a second data output signal representing the second identification information, or ii) configured to respond to receiving the first control signal by reading a first identification information (241) from the digital memory and provide a first data output signal representing the first identification information and comprising an indication that the digital controller has received the first control signal from the electronic logic circuit, the digital controller further being configured to respond to receiving the second control signal by reading the first identification information from the digital memory and provide a second data output signal representing the first identification information and comprising an indication that the digital controller has received the second control signal from the electronic logic circuit.

An RFID tag in accordance with claim 1, wherein the tamper conductor element

(211,212) is at least partly exposed on a surface of the RFID tag.

An RFID tag in accordance with one of the preceding claims, wherein the RFID tag comprises a plurality of tamper conductor elements (211,213,217), and the digital controller is configured to provide second data output signals identifying tamper conductor elements that are in the broken state.

An RFID tag in accordance with one of the preceding claims, wherein the electronic logic circuit is a digital logic capable of providing a high state and a low state in dependence on whether the tamper conductor element is in the intact state or in the broken state.

An item comprising an RFID tag in accordance with one of the preceding claims, wherein the RFID tag is attached to the item at a first contact point of the item and at a second contact point of the item, the first contact point of the item being attached to the tamper conductor element in such a way that when the item is modified in such a way that the first contact point and the second contact point exceeds a critical distance characteristic of the RFID tag, the second contact point of the item will remain attached to the RFID tag while the tamper conductor element will break, thereby assuming the broken state.

An item in accordance with claim 5, wherein the item has a fold between two item parts and the RFID tag attaches the two item parts to one another.

An item in accordance with claim 6, wherein the item comprises at least one of: a folded card, a folded advertisement, an envelope.