TAMPER DETECTION DEVICE

Abstract

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).

Claims

1. A tamper detection device (100) comprising an integrated circuit (IC) chip (2) comprising at least four terminals, the device further comprising an antenna (3) and a tamper loop (4) which may be in an open or closed state, wherein the tamper loop is coupled between the first and second terminal (8,9) of the IC chip, and the antenna (3) is coupled between the third and fourth terminal (10,11) of the IC chip, and wherein the IC chip comprises power supply circuitry, wireless communication circuitry for receiving and sending signals through the antenna, and tamper detection circuitry for detecting the status of the tamper loop (4), wherein: the device further comprises a light emitting diode (20) coupled also between the first and second terminal (8,9), and the IC chip (2) comprises circuitry for activating or deactivating the supply of current to the diode (20), following a command signal received by the antenna (3), the device (100) is configured so that: a signal transmitted to the device effective to activate the supply of current to the diode (20) causes the diode to be lit when the tamper loop (4) is in a predefined state, said signal fails to light the diode (20), when the tamper loop (4) is in the state opposite to the predefined state.

2. The device according to claim 1, wherein the LED (20) is coupled in parallel with the tamper loop (4), so that the signal causes the diode to be lit when the tamper loop is open.

3. The device according to claim 1, wherein the LED (20) is coupled in series with the tamper loop (4), so that the signal causes the diode to be lit when the tamper loop is closed.

4. The device according to claim 1, wherein: the tamper detection circuitry comprises a tamper control and read-out circuit (15) and a first and second switch (S1,S2) and wherein: the tamper control and read-out circuit (15) is connected to the first terminal (8) via a first conductor (16), the first switch (S1) is coupled between on the one hand a supply voltage (V.sub.sup) generated by the power supply circuitry, and on the other hand the first conductor (16), the second switch (S2) is coupled between the second terminal (9) and a reference voltage (V.sub.ref), with respect to which the supply voltage is generated, the tamper control and read-out circuit (15) is configured to be able to open or close the first and second switch simultaneously, and to read the status of the tamper loop (4) when both switches are closed, the circuitry for activating or deactivating the supply of current to the diode (20) comprises a LED control circuit (21), a third switch (S3) and a fourth switch (S4), wherein the third switch (S3) is coupled in parallel with the first switch (S1), the fourth switch (S4) is coupled in parallel with the second switch (S2), the LED control circuit (21) is configured to be able to open or close third and fourth switches (S3,S4) simultaneously.

5. The device according to claim 4, wherein a first and second resistor (R1,R2) are respectively coupled in series with the first and second switch (S1,S2)

6. The device according to claim 1, wherein the integrated circuit chip (2) is an RFID (Radio Frequency Identification) chip.

7. The device according to claim 1, wherein the device comprises a carrier (5), and wherein the IC chip (2), the antenna (3) and the LED (20) are mounted on the carrier (5).

8. The device according to claim 7, wherein the carrier (5) is a printed circuit board.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0008] FIG. 1 illustrates a tamper detection device known in the prior art.

[0009] FIG. 2 illustrates a tamper detection device according to a first embodiment of the invention.

[0010] FIG. 3 illustrates a tamper detection device according to a second embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0011] FIG. 2 shows an RFID tag 100 in 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 to FIG. 1. The RFID tag 100 comprises an integrated circuit chip 2 hereafter referred to an RFID chip 2, an antenna 3 and a tamper loop 4. The chip 2 and the antenna 3 are mounted on a carrier 5, which may be a printed circuit board. The chip 2, the antenna 3 and the loop 4 are shown schematically and are not drawn to scale. The tamper loop 4 is electrically coupled to two electrical conductors 6 and 7 fixed to or incorporated in the carrier 5. The conductors 6 and 7 are respectively connected to a first and second terminal 8 and 9 of the RFID chip 2. The antenna 3 is coupled between a third and fourth terminal 10 and 11 of the chip 2. The tamper detection circuitry comprises a tamper control and read-out circuit 15 coupled to the first terminal 8 via a conductor 16 that is itself coupled to a supply voltage Vsup generated by the power supply circuitry of the chip, via a first resistor R1 and a first switch S1, preferably realized as a CMOS transistor. The second terminal 9 is coupled to a reference voltage Vref (preferably ground) via a conductor 17, a second resistor R2 and a second switch S2. Closing the switches S1 and S2 simultaneously activates the tamper detection. The opening or closing of the switches S1 and S2 is operated on the basis of command signals transmitted to the chip 2, and transferred to the switches by the tamper control and-read out circuit 15 through conductors and 19. With the switches S1 and S2 closed, the tamper detection takes place by verifying the status of the tamper loop 4. Also and in the same way as described in relation to FIG. 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.

[0012] In addition to this, a LED (light emitting diode) 20 is mounted on the carrier 5. The LED 20 is coupled between the first and second terminal 8 and 9 and parallel with the tamper loop 4. The RFID chip 2 comprises circuitry for supplying current to the LED 20 in accordance with a command signal sent from an RFID transmitter. This circuitry comprises a LED control circuit 21 coupled to the RF circuitry of the chip 2, and a third and fourth switch S3 and S4. The third switch S3 is coupled between the supply voltage V.sub.sup and the conductor 16 that is also coupled to the tamper control and read-out circuit 15, i.e. the third switch S3 is coupled in parallel with the first switch S1. The fourth switch S4 is coupled between the conductor 17 and the reference voltage V.sub.ref, i.e. the fourth switch S4 is coupled parallel to the second switch S2. The LED control circuit 21 is configured to open or close both switches S3 and S4 simultaneously, through conductors 22 and 23, upon a command received by the antenna 3 and transmitted through the RF circuitry of the chip 2.

[0013] When both switches S3 and S4 are closed and when the tamper loop 4 is broken, the current flowing through the diode 20 is sufficient to light the diode so that it becomes visible with the naked eye. However, when the tamper loop 4 is closed, the loop 4 bypasses the LED 20, so that the LED fails to light up even though the switches S3 and S4 are closed. When multiple products are equipped with a device according to FIG. 2, the closing of the switches S3 and S4 in all of the devices will result in the LEDs 20 becoming visible on all products which have been tampered with. This allows a quick visual verification of tampered products.

[0014] When the switches S3 and S4 are open, i.e. the LED 20 is de-activated, tamper detection takes place in the same way as described above in relation to the device shown in FIG. 1. In this case, when the tamper loop 4 is closed, current flows through the loop 4 and not through the LED 20, so that the low tamper voltage indicates that the loop is closed. When the loop 4 is broken, the current flowing through the LED 20 is low enough so that the LED 20 voltage is high.

[0015] FIG. 3 shows a second embodiment of an RFID tag 100 in accordance with the invention. In this case, the diode 20 is coupled in series with the tamper loop 4. This device operates in the same way as the device of FIG. 2, except that the activation of the LED 20 by closing switches S3 and S4 leads to lighting of the LED on condition that the tamper loop 4 is closed. In other words, the device allows to visually indicate all products which have not been tampered with.

[0016] In both of the embodiments shown in FIGS. 2 and 3, the LED 20 is coupled to the same terminals 8 and 9 to which the tamper loop 4 is connected. The invention therefore does not require additional terminals on the chip 4.

[0017] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.