Tamper detection device

An integrated circuit chip (2), an antenna (3) and a tamper loop (4), and in addition to this, a light emitting diode (LED) (20), configured to be activated, i.e. supplied with current, upon a signal received by the antenna (3). The LED (20) is integrated in the device in such a way that when the LED is activated in the above-described way, the LED lights up so as to become visible by the naked eye, on the condition that the tamper loop (4) is in a predefined state, either open or closed. The LED (20) is coupled between the same terminals (8,9) of the integrated circuit chip (2) as the tamper loop (4).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Non-Provisional application claiming priority on European Patent Application No. 19171950.9 filed Apr. 30, 2019.

FIELD OF THE INVENTION

The present invention is related to an electronic transponder device for use in conjunction with a product and aimed at detecting whether the product has been tampered with.

STATE OF THE ART

A well-known tamper detection device of the above-described type is realized as an RFID (Radio-Frequency Identification) transponder or ‘tag’. Examples of such devices are described in documents US-A-2006/214789 and EP-A-3340114. The tag comprises an RFID integrated circuit chip, an antenna and a tamper loop. The integrated circuit chip is equipped with radio frequency circuitry for transmitting and receiving data from an RFID reader/transmitter, a memory for storing an identifier of a product and generally an identifier of the status of the tamper loop, tamper detection circuitry and power circuitry for providing power to the various components of the integrated circuit. The tag may be a passive tag, deriving power from the radio frequency signal itself, or an active tag provided with a power source such as a battery. The tamper loop is an electrically conductive connection that may be attached to a product, for example to the door of a container, in such a manner that unauthorized tampering causes the connection to be broken. The closed or open state of the loop is detected by the tamper detection circuitry of the tag and an identifier related to the state of the loop can be transmitted to the RFID reader.

The prior art device illustrated inFIG. 1is realised as an RFID transponder comprising an integrated circuit chip2hereafter referred to an RFID chip2, an antenna3and a tamper loop4. The chip2and the antenna3are mounted on a carrier5, which may be a printed circuit board. The chip2, the antenna3and the loop4are shown schematically and are not drawn to scale. The tamper loop4is electrically coupled to two electrical conductors6and7fixed to or incorporated in the carrier5. The conductors6and7are respectively connected to a first and second terminal8and9of the RFID chip2. The antenna3is coupled between a third and fourth terminal10and11of the chip2. Not all the building blocks of the RFID chip2are shown in detail. In particular, RF circuitry and power supply circuitry, as well as any memory and memory access circuitry are not shown, as these building blocks are well-known in the art. The tamper detection circuitry comprises a tamper control and read-out circuit15coupled to the first terminal8via a conductor16that is itself coupled to a supply voltage Vsup generated by the power supply circuitry of the chip, via a first resistor R1and a first switch S1, preferably realized as a CMOS transistor. The second terminal9is coupled to a reference voltage Vref (preferably ground) via a conductor17, a second resistor R2and a second switch S2. Closing the switches S1and S2simultaneously activates the tamper detection. The opening or closing of the switches S1and S2is operated on the basis of command signals transmitted to the chip2, and transferred to the switches by the tamper control and-read out circuit15through conductors and19. With the switches S1and2closed, the tamper detection takes place by verifying the status of the tamper loop4. When the tamper loop4is closed (non-tampered condition), the voltage difference between the first and second terminal8and9is low. When the loop is broken (tampered condition), the voltage difference is high. This voltage difference is detected by the tamper control and read-out circuit15and translated into a signal that may be transmitted via the antenna3to an RFID reader, thereby communicating the status ‘open’ or ‘closed’ of the tamper loop. Any details of the above-described components may be realized in accordance with known devices or their equivalents. The resistors R1and R2may for example be replaced by current sources.

One shortcoming of the existing transponders is that the verification of the state of the tamper loops of a plurality of tags requires the interrogation of each of the tags, which may be time-consuming and unpractical.

SUMMARY OF THE INVENTION

The invention aims to provide a tamper detection device that resolves the above-described shortcoming of existing devices. This aim is achieved by a device in accordance with the appended claims. A device according to the invention comprises the same components as existing devices, namely an integrated circuit chip, an antenna and a tamper loop, and in addition to this, the device comprises a light emitting diode (LED), configured to be activated, i.e. supplied with current, upon a signal received by the antenna. The LED is integrated in the device in such a way that when the LED is activated in the above-described way, the LED lights up so as to become visible by the naked eye, on the condition that the tamper loop is in a predefined state, either open or closed. The LED is coupled between the same terminals of the integrated circuit chip as the tamper loop.

The detection device of the invention thereby allows a quick visual inspection of the status of the tamper loop of one or more products equipped with the device.

FIG. 2shows an RFID tag100in accordance with a first embodiment of the invention. The device comprises all of the above-described components, which are indicated by the same reference numerals used above in relation toFIG. 1. The RFID tag100comprises an integrated circuit chip2hereafter referred to an RFID chip2, an antenna3and a tamper loop4. The chip2and the antenna3are mounted on a carrier5, which may be a printed circuit board. The chip2, the antenna3and the loop4are shown schematically and are not drawn to scale. The tamper loop4is electrically coupled to two electrical conductors6and7fixed to or incorporated in the carrier5. The conductors6and7are respectively connected to a first and second terminal8and9of the RFID chip2. The antenna3is coupled between a third and fourth terminal10and11of the chip2. The tamper detection circuitry comprises a tamper control and read-out circuit15coupled to the first terminal8via a conductor16that is itself coupled to a supply voltage Vsup generated by the power supply circuitry of the chip, via a first resistor R1and a first switch S1, preferably realized as a CMOS transistor. The second terminal9is coupled to a reference voltage Vref (preferably ground) via a conductor17, a second resistor R2and a second switch S2. Closing the switches S1and S2simultaneously activates the tamper detection. The opening or closing of the switches S1and S2is operated on the basis of command signals transmitted to the chip2, and transferred to the switches by the tamper control and-read out circuit15through conductors and19. With the switches S1and S2closed, the tamper detection takes place by verifying the status of the tamper loop4. Also and in the same way as described in relation toFIG. 1, the RFID chip comprises a number of components not shown in the drawing but well known in the art, such as RF circuitry, power supply circuitry, electronic memory and memory access circuitry. All components may be realized in accordance with known devices or their equivalents.

In addition to this, a LED (light emitting diode)20is mounted on the carrier5. The LED20is coupled between the first and second terminal8and9and parallel with the tamper loop4. The RFID chip2comprises circuitry for supplying current to the LED20in accordance with a command signal sent from an RFID transmitter. This circuitry comprises a LED control circuit21coupled to the RF circuitry of the chip2, and a third and fourth switch S3and S4. The third switch S3is coupled between the supply voltage Vsupand the conductor16that is also coupled to the tamper control and read-out circuit15, i.e. the third switch S3is coupled in parallel with the first switch S1. The fourth switch S4is coupled between the conductor17and the reference voltage Vref, i.e. the fourth switch S4is coupled parallel to the second switch S2. The LED control circuit21is configured to open or close both switches S3and S4simultaneously, through conductors22and23, upon a command received by the antenna3and transmitted through the RF circuitry of the chip2.

When both switches S3and S4are closed and when the tamper loop4is broken, the current flowing through the diode20is sufficient to light the diode so that it becomes visible with the naked eye. However, when the tamper loop4is closed, the loop4bypasses the LED20, so that the LED fails to light up even though the switches S3and S4are closed. When multiple products are equipped with a device according toFIG. 2, the closing of the switches S3and S4in all of the devices will result in the LEDs20becoming visible on all products which have been tampered with. This allows a quick visual verification of tampered products.

When the switches S3and S4are open, i.e. the LED20is de-activated, tamper detection takes place in the same way as described above in relation to the device shown inFIG. 1. In this case, when the tamper loop4is closed, current flows through the loop4and not through the LED20, so that the low tamper voltage indicates that the loop is closed. When the loop4is broken, the current flowing through the LED20is low enough so that the LED20voltage is high.

FIG. 3shows a second embodiment of an RFID tag100in accordance with the invention. In this case, the diode20is coupled in series with the tamper loop4. This device operates in the same way as the device ofFIG. 2, except that the activation of the LED20by closing switches S3and S4leads to lighting of the LED on condition that the tamper loop4is closed. In other words, the device allows to visually indicate all products which have not been tampered with.

In both of the embodiments shown inFIGS. 2 and 3, the LED20is coupled to the same terminals8and9to which the tamper loop4is connected. The invention therefore does not require additional terminals on the chip4.