CN101282633B - Method and device capable of shielding at least one non-contact smart card or RFID label - Google Patents
Method and device capable of shielding at least one non-contact smart card or RFID label Download PDFInfo
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- CN101282633B CN101282633B CN2007101488385A CN200710148838A CN101282633B CN 101282633 B CN101282633 B CN 101282633B CN 2007101488385 A CN2007101488385 A CN 2007101488385A CN 200710148838 A CN200710148838 A CN 200710148838A CN 101282633 B CN101282633 B CN 101282633B
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- smart card
- rfid label
- shield
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Abstract
The invention is related to an electromagnetic shielding sleeve, in particular a method and device capable of at least shielding a non-contact intelligent card or RFID label in order to prevent data exchange between the intelligent card and a wireless receptor (card reader). A technology is capable of at least shielding a non-contact intelligent card or RFID label, which is also able to shield the information exchange between the intelligent card or RFLD label or a remote transceiver. Said technology includes a material capable of generating a close current which is able to generate enough magnetic flux to at least balance out part of magnetic flux caused by said remote transceiver. Said material has an opening, a cavity, or disconnection without covering said intelligent card and RFID label to a large area.
Description
Technical field
The present invention relates to a kind of electromagnetic shielding cover, relate in particular to a kind of method and apparatus that can shield one non-contact smart card or RFID label at least, prevent between smart card or chip and the wireless interface receiver (card reader) exchanges data to take place.
Background technology
Contactless smart card can be in the data of institute's microarray strip stored larger capacity.Different with magnetic card and contact intelligent card is, contactless smart card can pass through magnetic field, less radio-frequency, and infrared ray, or the mode of light and card reader carry out exchanges data, and need not physically contact with card reader.Shift energy and data between card reader and the card and be the electromagnetic induction this technology that is coupled that relies on.The exchange of the signal of telecommunication is based on a loosely-coupled transformer.In order to shift these energy and data, the magnetic field that the coil in the terminal (card reader) can produce a high-strength frequency.When the noncontact card when this terminal (card reader), the part magnetic field of card reader makes card coil generation induced voltage thus by the coil (generally also claiming antenna) in the card.
The use of non-contact card chip technology makes information exchange more convenient.But because the non-contact information transfer character, unauthorized receiver may be stolen the information on the card.In addition, gone up energy if card leads to, data begin transmission, and the card carrier can not know card and do not authorized read purposefully and diffuse information.Such information steals where all contingent take the card people.At present, encryption technology and communications protocol are used to protect the integrality of card image and signal, can be more useful but add a physical protection layer.
Than the chip manufacturing of using in the smart card simpler be a kind of radio frequency identification chip (RFID).This class chip has several external forms to be used for different application scenarios, as material flow tracking and commercial affairs.Information in these chips too can be by remote access under the ignorant or unapproved situation of owner.
In view of the foregoing, protect those cards that uses the RFID technology, label and other various devices, the information that prevents them is stolen and is of great importance.At present, some main compositions that are used for the screening arrangement of RFID and contactless smart card all are big envelopes, need all seal (faraday's case) by protective device.This big envelope is a conductive materials, as metal, stops wireless signal to leave or enters this protective sleeve.For example, the product that CordTechnologies company has developed cries " intelligence shielding " can encase smart card fully, and it is made by the very high alloy of a kind of nickel content, non-contact card and external magnetic field can be shielded fully.Similarly, the U.S. was presented to 6 of Petsinger in 2000,121, what No. 544 patents were described is a cutting ferrule that can fully wrap contactless smart card, this cutting ferrule has adopted the material of the enough thick armoured magnetic field of a slice to make, and it can reduce to magnetic field intensity the degree that is not enough to drive smart card.
At present, the cutting ferrule of the armoured magnetic field of promising magnetic stripe card design, but purpose only limits to protect the data of storing on the magnetic stripe makes it not to be subjected to the external world the intersperse interference and the damage in magnetic field (as television set and loud speaker etc.).This type of example, please 5,288, No. 942 patent rights of authorizing 4,647, No. 714 patent rights of Goto in 1987 or authorizing Godry and Westfield in 1994 referring to the U.S..Protecting chip not to be subjected to electrostatic field effect in addition but still can accept the housing in magnetic field similarly.This type of example sees also 5,360, No. 941 patent No.s that the U.S. authorized Roes in 1994.More than two type shielding cutting ferrules can not control and when allow between smart card or label and the card reader exchanges data to take place, when do not allow.
Summary of the invention
RFID works under the frequency of 13.56 megahertzes according to the electromagnetic coupled principle.At first, the coil of card reader changes (magnetic flux) by the high speed in magnetic field, causes induced potential on the card coil, drives the RFID chip.This RFID chip can be regulated the resistance size of connecting with the card coil.This adjustment couples together by flux change and card reader in the card reader coil.The coupling of card reader coil and card coil is represented with parameter M, is called coefficient of mutual inductance between the two.The present invention is by reducing the effect that coefficient of mutual inductance reaches shielding.Under the low frequency condition, much larger than structure (0.1 meter), screen effect just can resolve into two parts when the wavelength of electromagnetic radiation (λ under 13.56 megahertzes=22 meter): high magnetic permeability shielding (μ) and vortex flow shield.
In non-faraday's basket structure, first kind of shielding is non-existent.The thin plate that high-permeability material is made can not shield the magnetic field vertical with this face.And the RFID device by inductance coupling high is stated, the magnetic field of parallel with receiving coil (just with the high-permeability material plane parallel) has nothing to do, because the electromotive force that causes at RFID coil internal magnetic field is zero thus.
In order to understand the effect of vortex flow shielding, we can be with the geometrical model of a simplification, as shown in Figure 1.With illustrating the effect that shows magnetic field, the rfid system of band shielding can be represented with three coils: card reader coil (1), shielded coil (2) and card coil (3) for clearer.As shown in Figure 2, at first, the electric current in the card reader coil (1) produces magnetic field (4).The variation of this magnetic field intensity makes shielded coil (2) (its resistance value is much smaller than the resistance value of card coil) produce induced current.This bucking current produces induced field (5) again, and the magnetic field that this induced field and card reader electric current produce offsets.The induced voltage that the induced voltage of card coil (3) therefore produces when not having shielded coil.
For function of shielding is proved effective, the spacing of shielded coil and card coil should be as far as possible little, and the resistance of shielding resistance also should be hanged down to produce enough induced currents and be offset original magnetic flux.We can go out the resistance of shielded coil from the circuit formula to calculating, and this resistance should be less than 4 π fL, and L is the coefficient of self-inductance of this housing here.
The present invention also plays a secondary shielding effect.The existence of housing energy has changed the coefficient of self-inductance of card coil, therefore changes the resonance coefficient of RFID chip/coil integral body, causes weakening the energy to the transmission of RFID chip.
We find, state for induction coupling rfid system, and housing does not need to cover each face of claimed device, i.e. faraday's cage.The one side of housing also need not all cover.In fact, as long as the housing of Any shape can produce the effect that perhaps closed current just can enough play shielding RFID.Unique necessary condition is that the electromotive force that housing produces is wanted to produce the magnetic flux that enough magnetic fluxs come all or part of counteracting to be produced by the card reader coil.Even the very little words of induction magnetic flux, perhaps, housing also can come into force, because the coefficient of self-inductance of the coil of RFID or non-contact card changes because of the existence of shielding material, this variable quantity may be enough to cause the change of resonance frequency of circuit, and will therefore change the electric weight of passing to chip.
The present invention is the housing of a kind of incomplete covering smart card or RFID label, and this housing also can have been worn hole or opening at shielding material.The advantage of this design is that it can allow light to contact the surface and the entity of smart card and RFID label with mechanical system, even can touch coil sections.In addition, owing to reduced the use amount of material, can reduce cost greatly.
Another advantage of discontinuous ground plane is how and whether it provide the possibility of the folding in Control current path, and this just makes the user can determine whether to allow RFID label, contactless smart card and other RFID devices be read.Like this, can easily not control access rights even the RFID product is not taken out in the housing yet.Card has only when needed and just is read, and all the other times all are in protected state.The shield loop switch can be controlled with the mode of machinery, electricity or light.In addition, such control mode not the right and wrong very important person for interfering.For example, on the extraneous light-emitting diode of illumination in being integrated in RFID, just can open circuit, stop electric current in housing, to flow.Card just can be read this moment, unless outer light is turned off or blocked, maybe will block from housing and take out.This housing does not need to make with simple metal; it can be the sandwich of synthetic or metal and insulating material; such structure can be protected the RFID device from machinery, optics, chemistry, radiation, these aspects that insulate; perhaps can increase integrally-built fastness, or strengthen application performance in others.Shielding material must have very little alternating-current resistance.μ/μ vacuum=1, thickness meet or exceed skin depth, nonferrous metal that monolithic conductive is strong is best manufactured materials, but are not unique.Aluminium is well practical the selection, because except excellent conducting performance, and the big very easy acquisition of aluminum slice of opening, relatively cheap, very strong anti-corrosion property (especially to sodium chloride and oxygen) is also arranged, with other compositions together after Overheating Treatment, aluminium alloy can reach good ductility and hardness.
Description of drawings
Fig. 1 is a card reader, the simplified model figure of housing and card coil.
Fig. 2 is the physical principle figure of eddy-current screen.
Several particular implementation illustrations under Fig. 3,4,5, the 6th, the present invention.
Embodiment
The present invention is to use the self-induction of the mutual inductance that changes between card reader and the card and card antenna to realize the shielding of various different application.The present invention can be used for shielding the remote-controlled certificate card that reads, and this is stuck in still can be visual in the cutting ferrule by the external world.Several different shielding cutting ferrules have been made product.
Though also can use other materials, aluminium flake but is very cheap and effective shielding material.The one side that covers standard intelligent card with aluminium flake just can fully play shield effectiveness (for example, the model SDIO10 that the SCM microsystems is sold, 13.56MHz card reader).Even card skids off 2.5 centimetres from cover, one side outside being exposed to of smart card, housing can be reduced to 18% with the maskless Card Reader distance of standard.In order to prevent weakening of shield effectiveness that this is faint, can on cutting ferrule, load onto mechanical device card is fixed, so just can stop card in overlapping, to skid off, thereby make it to be adequately protected.
A kind of concrete implementation method is that aluminium flake or aluminium alloy (6) are clipped in two plastics (7 and 8) centre, as the back side of housing.Design as shown in Figure 3.The advantage of this cutting ferrule is an advantages of good shielding performance, can protect ID card and shielding material and cost low.Weak point is, because many one deck plastic sheets, the cutting ferrule volume of the unshielded function of volume ratio of this cutting ferrule is big.Another kind of implementation method is directly to use aluminum or aluminum alloy (6) to do the cutting ferrule back side.This design as shown in Figure 4.
Fig. 5 is the design principle figure that recommends.Among this figure, light (10) is received by a light measurer (1), and this light measurer control changes the induced current reduction in the card coil (3) by the electric current of ground plane (2), influences the actuating force to RFID circuit and electronics (12) successively.This device can be controlled housing, makes that the smart card user does not need for the Card Reader sheet card to be taken out from housing.This design allows card be not easy to be in non-shielding state when not noting, has improved convenience and fail safe to a certain extent.Because the surface of card still can contact in this design, means optics, machinery or electricity can be used for the effect of mask switch.For example, can make electricity with electromagnetic wave starts.Also have the means of other a lot of electronics and machinery can substitute this optical transceiver/switch; State how to realize that this control is conspicuous in the industry personage.For example, the triode that uses easy push-button switch or control by microprocessor, and any other can temporarily disconnect the device by the electric current of protective sleeve circuit.Perhaps, the user also can select for use as Fig. 3 or design shown in Figure 4, card is released toward the direction of leaving ground plane by the central closing of housing with mechanicals efforts, allows it temporarily be in not conductively-closed state.Obviously, use snap close can mechanically shielding be removed too.
Another kind of design is shown in Figure 6, and light sensation device and RFID circuit or antenna are integrated, directly control smart card, like this with regard to unwanted housing.In this design, comprised optical detection (11) function in the RFID electronics (12), decide the RFID chip request signal whether reading card device coil sends to make reflection by the reception of light.Another kind of simple alternative mean is mobile light detection device, comes control antenna loop (3) electric current rather than RFID chip.Optical transceiver/switch can replace with a lot of other electric switch or mechanical switchs.Optical means described here comprises from radio frequency to ultraviolet whole frequencies.
Experiment confirm the effectiveness of this screening arrangement.Even when card directly contacted with card reader, this housing also can stop card reader to read card fully.Can the design of clear Fig. 5 (use push-button switch) of test chart of power mode turn-off current can be controlled reading of rfid card really.
Claims (18)
1. method that can shield one non-contact smart card or RFID label at least, described method can shield the information exchange of smart card or RFID label and remote transceiver; Described method comprises a kind of material that can produce closed current, and this electric current can produce enough magnetic fluxs and offset the magnetic flux that part is caused by described remote transceiver at least; Described material has an opening, the hole, or disconnect, need not cover described smart card and RFID label in large area; Described opening, hole or disconnection are used for preventing that described electric current from flowing in described closed-loop path; Described opening, hole or disconnection open or close with optics or electronic method.
2. a kind of method that can shield one non-contact smart card or RFID label at least described in claim 1 is characterized in that, the described material that comprises is plane or curved flaky material.
3. a kind of method that can shield one non-contact smart card or RFID label at least described in claim 1 is characterized in that, described material has given shape makes the external world can see the surface or the content of described smart card or RFID label.
4. a kind of method that can shield one non-contact smart card or RFID label at least described in claim 1 is characterized in that, described material has given shape makes the external world can touch the surface or the content of described smart card or RFID label.
5. a kind of method that can shield one non-contact smart card or RFID label at least described in claim 1, it is characterized in that, described opening, hole or disconnection are connected by circuit, make electric current flow to the other end from an end of described material, or to whole material.
6. a kind of method that can shield one non-contact smart card or RFID label at least described in claim 1 is characterized in that, described opening, the hole or disconnect by or do not connect by circuit by artificial interference, make described electric current in housing, flow.
7. as claim 1, a kind of method that can shield one non-contact smart card or RFID label at least described in 2,3,4,5 or 6 is characterized in that described smart card or RFID label can be fixed, and can not move to a certain position and weakens the effectiveness of housing.
8. a kind of method that can shield one non-contact smart card or RFID label at least described in claim 1 is characterized in that, the user is by the mechanical action or the application of force, move, depart from, the distortion screening arrangement, make it to leave card, make smart card to be read.
9. method by the readability of optics control contact or contactless type smart card or RFID label, it is characterized in that, described smart card or RFID label adopt the described method of claim 1 to shield one non-contact smart card or RFID label at least, and smart card or RFID label only just can be read when light control functionality activates.
10. device that can shield one non-contact smart card or RFID label and remote transceiver communication at least, described device is by forming with the lower part:
A kind of material that allows electric current in a closed-loop path, to flow and respond to enough magnetic fluxs, this magnetic flux can be offset the magnetic flux that is produced by the remote control transceiver to small part, described material has an opening, hole or disconnection, and do not need to cover smart card or RFID label in large area;
Described device is fixed relative contactless smart card of described material or RFID label, makes described material can produce enough magnetic field, can offset the magnetic flux that is produced by remote transceiver to small part;
Described opening, hole or disconnection can be used for preventing that described electric current from flowing in described closed-loop path; Described opening, hole or disconnection open or close with optics or electronic method.
11. a kind of device that can shield one non-contact smart card or RFID label and remote transceiver communication at least described in claim 10 is characterized in that the described material that comprises is plane or curved flaky material.
12. a kind of device that can shield one non-contact smart card or RFID label and remote transceiver communication at least described in claim 10, it is characterized in that described material has given shape makes the external world can see the surface or the content of described smart card or RFID label.
13. a kind of device that can shield one non-contact smart card or RFID label and remote transceiver communication at least described in claim 10, it is characterized in that described material has given shape makes the external world can touch the surface or the content of described smart card or RFID label.
14. a kind of device that can shield one non-contact smart card or RFID label and remote transceiver communication at least described in claim 10, it is characterized in that, described opening, hole or disconnection are connected by circuit, make electric current flow to the other end from an end of described material, or to whole material.
15. a kind of device that can shield one non-contact smart card or RFID label and remote transceiver communication at least described in claim 10, it is characterized in that, described opening, the hole or disconnect by or do not connect by circuit by artificial interference, make described electric current in housing, flow.
16. a kind of device that can shield one non-contact smart card or RFID label and remote transceiver communication at least described in claim 10, it is characterized in that, described smart card or RFID label can be fixed, and can not move to a certain position and weaken the effectiveness of housing.
17. a kind of device that can shield one non-contact smart card or RFID label and remote transceiver communication at least is characterized in that described in claim 10, the user is by the mechanical action or the application of force, move, depart from, the distortion screening arrangement, make it to leave card, make smart card to be read.
18. device by the readability of optics control contact or contactless type smart card or RFID label, it is characterized in that, described smart card or RFID label adopt the described device of claim 10 to shield one non-contact smart card or RFID label at least, and described smart card or RFID label only just can be read when light control functionality activates.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101488385A CN101282633B (en) | 2007-08-30 | 2007-08-30 | Method and device capable of shielding at least one non-contact smart card or RFID label |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101488385A CN101282633B (en) | 2007-08-30 | 2007-08-30 | Method and device capable of shielding at least one non-contact smart card or RFID label |
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| Publication Number | Publication Date |
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| CN101282633A CN101282633A (en) | 2008-10-08 |
| CN101282633B true CN101282633B (en) | 2011-11-23 |
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| CN2007101488385A Expired - Fee Related CN101282633B (en) | 2007-08-30 | 2007-08-30 | Method and device capable of shielding at least one non-contact smart card or RFID label |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101630357B (en) * | 2009-07-28 | 2014-11-26 | 吴斐 | Radio frequency identification device capable of enhancing induced field strength of electromagnetic wave |
| CN110518414B (en) * | 2019-08-19 | 2024-04-19 | 佛山市云米电器科技有限公司 | A shield assembly for USB3.0 signal crosstalk |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040061612A1 (en) * | 2002-09-26 | 2004-04-01 | Paradiso Joseph A. | Tag interrogation with observable response signal |
| CN1938717A (en) * | 2004-07-08 | 2007-03-28 | Ykk株式会社 | Article with wireless ic tag |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040061612A1 (en) * | 2002-09-26 | 2004-04-01 | Paradiso Joseph A. | Tag interrogation with observable response signal |
| CN1938717A (en) * | 2004-07-08 | 2007-03-28 | Ykk株式会社 | Article with wireless ic tag |
Non-Patent Citations (1)
| Title |
|---|
| JP特开2003-6599A 2003.01.10 |
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| CN101282633A (en) | 2008-10-08 |
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Granted publication date: 20111123 Termination date: 20210830 |