NL1003952C2 - Radio frequency interface to attach to smart card - Google Patents

Abstract

The interface consists of a transparent plastic foil (1) with conductive tracks printed its underside. When the foil is applied to the card, electrical contact is made between contact pads on the card and conductive areas (3, 4) on the printed foil. The conductive areas (3,4) are connected to the inductive loop (2) which is set into the foil. The foil is between 10 and 20 microns thick.

Description

-1-

PROXIMITY STICKER INTERFACE FOR CHIP CARD

The invention relates to a contactless interface for a standard smart card or electronic chip card, in the form of a sticker, provided with an electronic circuit, which can be retrofitted to any standard contact chip card. By means of a contactless radio-frequency (RF) transceiver system in the form of a card reader, communication can take place in this way, which otherwise takes place via the electrical contacts of the card.

The chip card with contacts has gradually become a familiar concept in teletone-15 and payment traffic and there are large numbers of these cards in circulation.

For a number of applications, where it is important to realize a high transaction speed, in particular for public transport, where large numbers of users must be able to be handled in a short time, a contactless manner of handling is desired. Inserting the contact card in a slot hereby takes too much time, and the reading equipment, provided with slots, is also quite sensitive in this environment to vandalism.

Applicant's Dutch patent application 1002195 describes a modular system for adding such contactless functionality to the standard chip card 30 provided with contacts by means of modules. A drawback here is that the basic chip card with contacts has to be removed from the module block each time, if this chip card is to be used in a conventional card reader provided with contacts and 1003952 -2- a slot.

The present invention aims to provide a solution for this and will be described below with reference to three figures.

Figure 1 schematically shows the contactless sticker interface according to the invention.

Figure 2 shows a standard chip card with contacts on which this interface can be fitted.

Figure 3 schematically shows the electronic circuit 10 of the interface circuit used.

As shown in figure 1, the contactless interface according to the invention consists of an extremely thin, printed or transparent plastic foil (1) of, for example, polyester, with a thickness of about 10-20 microns. This foil (1) is also provided with an extremely thin metal foil, which, for example, by etching away this metal locally, has been transformed into a coil (2) for the contactless RF interface and a carrier for the electronic chip (3). This electronic chip (3) is connected to the coil (2) and the connecting tracks to the contact surfaces (4) with which the sticker interface on the contacts of the contacts is connected by means of "wire bonding" or by means of the so-called "tape-automatic bonding". chip card is connected. At the outer end of the coil, an electrical connection must be made to the chip (3), the other windings must be passed without making a short circuit. This can be realized, for example, by extending the foil (1) with a lip (5), on which a metal track with connecting surface (6) connected to the coil end is arranged. This lip is folded around the card when the interface is applied to the chip card, whereby the connection surface (6) connects via an opening in the card to connection surface (7), which is also connected to the chip (3 via a track). ). Openings in the foil (1) are placed under the connection surfaces (4), which are connected to the contacts of the chip card, so that these 1003952 -3 contact surfaces (4) are also on the back through these openings in the foil (1). be reachable. After the chip (3) has been applied to the foil (1) with the interface circuit and possibly covered, an adhesive layer is then applied on the side of the coil 5, which is placed at the location of the connecting surfaces (4), (6) and (7) is electrically conductive.

Before the interface can be attached to the chip card (8) of figure 2, two openings (9) and (10) must be made in this chip card. Opening (9) is formed such that the covered chip (3) fits snugly therein, the height of the cover not exceeding the thickness of the chip card (8). Opening (10) serves for the connection of connection surface (6) to connection surface (7) of the sticker interface, after the lip (5) 15 is folded around the chip card (8). The connecting surfaces (4) of the sticker interface connect to the contacts (11) of the chip card (8) via the electrically conductive adhesive. After the sticker interface has been applied to the chip card, it can be used normally again, via the back of the 20 connection surfaces (4), which may be locally gilded, and the openings behind these surfaces in the foil (1).

After applying the sticker interface, the chip card can also be used contactlessly, via the coil (2) and the interface chip (3), whereby, as schematically indicated in figure 3, the power supply (VCC), the reset signal (RST), the clock signal (CLK), the input / output signal (I / O) and the ground signal (GND) are generated by the electronic circuit of the interface chip (3).

The electronic circuit of the interface chip (3) 30 therefore comprises a rectifying circuit in order to be able to extract the required energy from the RF carrier wave of a contactless transmitter / receiver or reading device. Also in this circuit, also from the RF carrier, a clock signal is derived intended for the micro-processor of the 35 chip card (8). Subsequently, this circuit contains a modulator / demodulator circuit, with which it is possible to transfer data signals to and from the transmitter / receiver 10 0 3 9 5 2 -4-. Finally, a reset signal is generated when the supply voltage is stable. This signal is not necessary for all chip cards, because sometimes an internal reset signal is generated in these cards. The interface circuit of chip (3) is known per se and will therefore not be described in further detail. The carrier frequency and the modulation technique for the interface sticker is preferably chosen in accordance with the international ISO standards ISO-10536 or ISO-14443, so that respectively the contactless cards according to these standards can also function on the contactless reading devices for the chip cards provided with a sticker interface according to the invention and vice versa.

The total thickness of the sticker interface is such that after application of this interface the chip card can remain within the maximum permitted thickness of 0.84 mm and thus does not impose any restrictions on the standard reading devices.

By slightly compressing the card after application of the interface under elevated temperature, the influence of the added thickness can be further limited. It is also possible, for example by scraping, to locally remove some plastic material from the chip card, for example at the location of the folded-over lip.

Instead of using one coil, for both the energy supply and the data signals, it is also possible to use a separate coil for the data signals, so that these signals are not affected by the relatively large currents required for the energy supply. However, this makes the implementation of the sticker interface slightly more complex, because multiple connections are required to both the interface chip and from the inside to the outside of the coils. These connections can optionally also be realized with two conductor layers, which are insulated from each other. Naturally, other connection techniques are possible for the electrical connection between the sticker interface and the chip card, such as bonding, soldering or spring contacts.

1003952

Claims (6)

1. A contactless radio-frequency interface for a standard contact chip card, characterized in that this interface, consisting of a coil and an electronic circuit, is built up on an extremely thin foil which can be applied to the chip card in the form of a sticker and which need not be removed to continue to use the contact chip card in this standard contact chip card reader after this interface is installed. A contactless radio-frequency interface for a standard contact chip card according to claim 1, characterized in that the electronic circuit required for this interface is housed in an integrated circuit, which, including any cover, is not thicker than the thickness of a standard contact chip card, so that this circuit, which is located in a pre-arranged opening in the chip card after the interface has been applied to the chip card, does not protrude above the surface of this contact chip card. A contactless radio-frequency interface for a standard contact chip card according to one or both of the preceding claim (s), characterized in that the electrical connection required from the outside of the coil to the inside is obtained by a lip provided with a conductor to fold the chip card and electrically connect, via a pre-arranged opening in the chip card, to a conductor on the inside of the coil, or vice versa. 1003952 -6- A contactless radio-frequency interface for a standard contact chip card according to one or more of the preceding claim (s), characterized in that the electronic circuit of the interface comprises a circuit 5, which provides the power supply, a clock signal, a data input / output signal and possibly a reset signal, by deriving this provision and signals from or adding them to the radio-frequency signal of the contactless transmitter / receiver. A contactless radio-frequency interface for a standard contact chip card according to one or more of the preceding claim (s), characterized in that electrically conductive glue is used to obtain the necessary electrical connections between the sticker interface and the chip card. A contactless radio-frequency interface for a standard contact chip card according to one or more of the preceding claim (s), characterized in that a second coil is used for the 20 data signals at the contactless interface. 1003952