AN ASSEMBLY COMPRISING A NOISE EMITTING ELEMENT

Abstract

An assembly of a standard RFID/NFC element and a scrambling element for outputting wireless noise in response to a wireless request signal from a terminal, such as NFC, RFID or the like. The scrambling element has a noise generating circuit and an antenna for receiving the request signal and outputting a voltage. The scrambling element further comprises a voltage increasing element receiving the voltage from the antenna and feeding a higher voltage to the circuit to have the circuit start operation faster than the circuit of the standard RFID/NFC element.

Claims

1. An assembly of: a first wireless communication element comprising: a first antenna configured to receive a wireless signal and output an output voltage, the wireless signal having a wireless signal frequency, a first circuit connected to the first antenna and being configured to, when receiving the output voltage, output an output signal to the first antenna, the first antenna being configured to output, based on the output signal, a wireless output signal having an output frequency, and a second wireless communication element comprising: a second antenna configured to receive the wireless signal and output a first voltage, a voltage increasing element connected to the second antenna, the voltage increasing element being configured to increase the first voltage by a predetermined factor to a second voltage and output the second voltage, a second circuit connected to the voltage increasing element and being configured to, when receiving the second voltage, output a noise signal to the second antenna, the second antenna being configured to, on the basis of the noise signal, output a wireless noise signal having a frequency component in a frequency band of the wireless signal frequency or the output signal frequency, wherein: the first circuit is configured to start outputting the output signal when the output voltage reaches a first threshold voltage, the second circuit is configured to start outputting the noise signal when the second voltage reaches a second threshold voltage and the first threshold voltage exceeds the second threshold voltage divided by the predetermined factor.

2. An assembly according to claim 1, where the voltage increasing element has a first and a second terminal both connected to the second antenna, a first, a second and a third capacitor and a first and a second diode, where: the second and third capacitors are connected in series between a predetermined voltage and a first conductor, the first terminal is connected between the second and third capacitors, the first and second diodes are connected in series between the predetermined voltage and the first conductor, the second terminal of the coil is connected between the first and second diodes, and the first capacitor is connected between the predetermined voltage and the first conductor, the first capacitor being configured to feed the second voltage from the first capacitor to the circuit.

3. An assembly according to claim 1, wherein the second circuit is configured to output as the noise signal a square signal and/or the noise signal comprises a number of pulses, where a width of a pulse is 3 s.

4. An assembly according to claim 1, wherein the noise signal is a periodic signal with a duty cycle of 50% or less.

5. An assembly according to claim 1, wherein: a frequency of the noise signal is at least 50% of a predetermined frequency, and wherein the duty cycle is at least 30% or a frequency of the noise signal is no more than 50% of a predetermined frequency, and wherein the duty cycle is no more than 30%.

6. An assembly according to claim 1, wherein the second wireless communication element further comprises a voltage limiting element configured to limit the second voltage to a voltage not exceeding a predetermined maximum voltage.

7. A method of operating an assembly comprising: a first wireless communication element comprising a first antenna and a first circuit and a second wireless communication element comprising a second antenna, a voltage increasing element and a second circuit, the method comprising the steps of: 1. an emitter outputting a wireless signal, 2. the first and second antennas receiving the wireless signal and outputting an output voltage and a first voltage, respectively, 3. the voltage increasing element receiving the first voltage and outputting a second voltage, the second voltage being larger than the first voltage and 4. the first and second circuits receiving the output voltage and the second voltage, respectively, and outputting an output signal and a noise signal, respectively, to the first and second antennas respectively, the first and second antennas outputting, based on the output signal and noise signal, respectively, a wireless output signal having an output frequency and a wireless noise signal, respectively, where the wireless noise signal has a frequency component in a frequency band of the output signal and wherein the second circuit starts outputting the noise signal before the first circuit starts outputting the output signal.

8. A method of operating an assembly comprising: a first wireless communication element comprising a first antenna and a first circuit, the, first circuit being configured to check whether a signal received from the first antenna conforms to predetermined requirements and, only if so, to output an output signal to the first antenna and a second wireless communication element comprising a second antenna, a voltage increasing element and a second circuit, the method comprising the steps of: 1. an emitter outputting a wireless signal having a wireless signal frequency, 2. the first and second antennas receiving the wireless signal and outputting an output voltage and a first voltage, respectively, 3. the voltage increasing element receiving the first voltage and outputting a second voltage, the second voltage being larger than the first voltage and 4. the first and second circuits receiving the output voltage and the second voltage, respectively, 5. the second circuit outputting a noise signal to the second antenna, without the first circuit outputting an output signal to the first antenna, so that the antenna outputs a wireless noise signal having a frequency component in a frequency band of the wireless signal.

9. A method according to claim 7, wherein the second voltage is at least 2 times the first voltage.

10. A method according to claim 7, wherein the noise signal is a square signal and/or the noise signal comprises a number of pulses, where a width of a pulse is 3 s or less.

11. A method according to claim 7, wherein the noise signal is a periodic signal with a duty cycle of 50% or less.

12. A method according to claim 7, wherein: a frequency of the noise signal is at least 50% of a predetermined frequency, and wherein the duty cycle is at least 30% or a frequency of the noise signal is no more than 50% of a predetermined frequency, and wherein the duty cycle is no more than 30%.

13. A method according to claim 7, wherein, in step 2, the output voltage is no less than 90% of the first voltage and no more than 110% of the first voltage.

14. A method according to claim 7, wherein step 4 comprises the step of limiting the second voltage to a voltage not exceeding a predetermined voltage before feeding the limited voltage to the second circuit.

Description

[0117] In the following, preferred embodiments of the invention will be described with reference to the drawing, wherein:

[0118] FIG. 1 illustrates a preferred embodiment according to the invention,

[0119] FIG. 2 illustrates an embodiment of the voltage increasing element.

[0120] In FIG. 1, an assembly is illustrated having a standard RFID/NFC card 60, such as a credit card or an ID card, having an antenna 15 and a circuit 200, and an element, such as a thin, credit card shaped element 10 which has an antenna 15 connected to a voltage increasing element 20 via terminals 16 and which is again connected to a noise generating circuit 30 via connections 17.

[0121] The antenna 15 may be a standard coil used for NFC or RF communication, such as for RFID communication or other wireless communication often used for identification, payment or similar purposes. The antenna 15 may be the same type of antenna or another type of antennabut again may be a standard antenna type.

[0122] The circuit 200 is connected to the antenna 15 in the standard manner. When receiving a wireless signal from the reader 50, the antenna will output an output voltage to the circuit, which derives power from this signal and generates an output signal to the antenna 15. The output signal usually comprises identity information and/or other sensitive information for a genuine or trustworthy reader 50 to receive.

[0123] However, fraudulent readers 50 may exist which will attempt to access this output signal to illegally use that information against the will of the owner. This is to be avoided.

[0124] The circuit 30 may be connected to the element 20 only, or one terminal thereof may be connected directly to the coil if desired (hatched line).

[0125] The circuit 30 is configured to output, when powered, a noise signal (see below) in order to prevent or block communication between the RFID/NFC terminal 50 and the RFID/NFC element 60, which is also in the vicinity of the element 10.

[0126] When the terminal 50 outputs its usual request signal, the antenna of the element 10, as in usual ID/payment cards, will receive the signal and output power and thus a voltage. In usual RFID/NFC elements, this power is fed to a chip 200 which then will operate to respond to the request signal with an identification of the RFID/NFC element. The element 60 may be a standard RFID/NFC element.

[0127] However, such responses may not always be desired, whereby blocking or prevention of this communication is desired. It is not practical to prevent the terminal 50 from outputting the signal, and in some situations, criminals will carry terminals in crowded spaces, such as trains, in order to obtain information from RFID/NFC elements 60. Thus, the terminals 50 are not controllable or trustworthy to the desired extent.

[0128] The present element 10, however, will, when sensing a signal from a terminal 50, itself output a noise signal aimed at preventing near-by NFC/RFID elements 60, such as ID or payment cards, from either receiving or correctly interpreting the terminal request signal (the NFC/RFID elements usually only respond to a request signal complying to a given standard or protocol), or at outputting a signal scrambling any signal output by the NFC/RFID elements 60.

[0129] As the energy obtainable from a request signal depends a lot on the distance between the terminal antenna and the antenna of the elements 10/60, it is highly desired that the present element 10, at least when positioned at the same distance to the terminal 50 as the element 60, is faster than the NFC/RFID element 60 in order to ensure that the scrambling or noise emitting starts so early that the NFC/RFID element 60 does not have time to output its response, before the noise signal is output.

[0130] The chip 30 will start operating when the voltage fed thereto reaches a threshold voltage. The voltage output of the coil 15 will increase, as the field is detected and the power collected increases. The operation of the voltage increasing element 15 is to receive the power and voltage output of the antenna 15 and increase the voltage and feed this increased voltage to the circuit 30. As a result thereof, the circuit 30 will start operation earlier and thus be faster to perform its preventing/blocking action compared to the circuit 200 not having this voltage boost.

[0131] In some circumstances, however, it is actually desired to have the ID or payment card 60 respond to a terminal request signal, such as when entering a secured door or making a payment. Thus, it is desired to be able to prevent the operation of the circuit 30. To this effect, a switch or other user operable element 40 may be provided. The user may operate this element 40 and thereby send a signal to the circuit 30 to not operate.

[0132] The element 40 may be a standard switch, a wireless receiver for signals output by e.g. a mobile telephone of the user, or a piezo element outputting a voltage when bent, so that the user need only deform (or just tap) the element 10 to stop the noise outputting operation.

[0133] The noise outputting operation may be carried out in many manners. In one embodiment, the noise outputting step comprises the outputting of sharp pulses, such as square pulses. The advantage of such sharp pulses or sharp corners is that these will generate an output not only at the frequency of the pulses but also at harmonics thereof. Thus, a noise signal with a wider spectrum may be output.

[0134] Usually, the request signal from the terminal 50 is 105.9 kHz and the response from a RFID/ID/NFC card 60 is 847.5 kHz. In principle, the noise signal may operate in any of these frequency bands.

[0135] In one situation, the noise signal has a frequency within 10% of one of the above frequency bands. However, it is also possible to provide a noise signal with a frequency lower than one of the frequency bands, especially if the pulse width of the signal is reduced. Lower pulse widths create more harmonics which therefore will also create noise at higher frequencies.

[0136] Also, the duty cycle may be selected. It is noted that a low duty cycle outputs the signal only during a lower proportion of the period of the signal. In the remaining portion of the period of the signal, no signal is output, whereby power may be collected by the element 10 for continued operation of the circuit 30.

[0137] Thus, a duty cycle of at least 30%, such as at least 40%, such as around 50% may be selected especially if the frequency of the noise signal is at or at least within 20% or 10% of the desired frequency, whereas a duty cycle of no more than 30%, such as no more than 20%, such as no more than 15% may be desired, if the frequency of the frequency to be blocked is at least twice the frequency of the noise signal.

[0138] FIG. 2 illustrates a preferred embodiment of the voltage increasing element 20. The element is provided to the left of and at the top of the circuit 30. To the right, the sensor 40 is illustrated, here in the form of a piezo element and a variable resistor in addition to a voltage divider all provided to protect the circuit 30 from the high voltage potentially output of the piezo.

[0139] The element 20 receives the signal from the terminals 16 and feeds the signal from the upper terminal (through a resistor) to the circuit 30. This signal is fed between two diodes, D2 and D3 provided between an output and ground.

[0140] The signal from the lower terminal is fed between two capacitors, C2 and C3, also provided between ground and the output.

[0141] The operation of this set-up is that when the signal is positive on the upper terminal and thus negative on the lower terminal, D2 will be conducting while the diode D3 will be blocking, so the voltage across C2 will build up.

[0142] When, on the other hand, the signal is negative on the upper terminal and positive on the lower terminal, D3 will be conducting while the D2 will be off, so the voltage across C3 will build up.

[0143] The voltage output is fed to the capacitor C1 which holds the voltage fed to the circuit 30 for operation. A LED D1 is provided for protecting the circuit 30 from any excessive voltage output of the capacitor C1. D1 may be dimensioned to be conducting at a voltage close to the max voltage for the circuit 30. D1 may of course be replaced by any other circuit having the same effect, such as a circuit disposing of the power by creating heat (a resistor).

[0144] Ignoring the voltage drop in D2 and D3, the voltage across both C2 and C3 will be that received from the coil, i.e. the first voltage, V. Then, the voltage fed to C1, the second voltage, is the voltage across C2+the voltage across C3, i.e 2*V. This circuit thus acts as a voltage doubler.

[0145] When operating, the circuit 30 outputs the noise signal to the upper terminal and thus to the antenna.

[0146] The element 10 preferably is provided in the vicinity of the RFID/ID/NFC/payment cards or items to protect. The element 10 may be embodied as a thin element which may be glue to a wireless card, for example, to protect or to e.g. a wallet or other holder for such cards.

[0147] Any voltage increase may be selected. As mentioned above, the voltage increasing circuit may be implemented in a number of manners, including in discrete components. Some examples are:

[0148] http://www.circuitstoday.com/voltage-doubler-circuit-using-ne555

[0149] http://www.electronics-tutorials.ws/blog/voltage-multiplier-circuit.html

[0150] Naturally, the element 60 may also have a voltage increasing element as that of the element 10. A reason for increasing the voltage fed to the circuit 200 may be to increase the range thereof. In this situation, the voltage increasing element 20 of the element 10 should be adapted (or the threshold voltage of the circuit 30), so that the circuit 30 nevertheless will reach its threshold voltage before the circuit 200 does.