METHOD FOR DETERMINING A VALUE OF AN ELECTROMAGNETIC FIELD STRENGTH, METHOD FOR COUPLING A READER, CHIP CARD AND READER FOR A CHIP CARD

Description

[0001] The invention relates to a method for determining the value of an electromagnetic field strength and a chip card.

[0002] Such methods are known, for example, from EP 3 278 265 B1, EP 3 070 636 B1, De 10 2004 039650 A1 or Finkenzeller et al: "RFID Handbook: Fundamentals and practical applications of inductive radio systems, transponders and contactless chip cards" (2002).

[0003] Card-shaped data carriers, especially chip cards, are used in many areas, for example, for processing cashless payments, as identification documents, or for verifying access authorizations. A chip card consists of a card body and an integrated circuit embedded in the card body, for example, in the form of a chip module containing a chip. The chip module is inserted into a cavity or module opening in the card body.

[0004] The following section examines chip modules or chip cards with an integrated coil, enabling contactless communication. For example, chip card controllers with RFID functionality can be used. Card bodies with a metallic core, in the form of a metallic core layer or core element, can also be considered, as well as cards with Dual Interface (DI) functionality, where the card body is partially or entirely made of metal. The functionality of such a card involves the use of a chip module that itself contains a coil (coil-on module). This coil couples to the metallic card body.

[0005] In practice, knowledge of the electromagnetic field strength applied to a chip card can be of interest, for example during the production of the chip card in the form of a functional test or during communication or coupling of the chip card with a reader.

[0006] However, the electromagnetic field strength of chip card production machines cannot be easily determined using measuring devices and systems. These systems are designed so that a coil, shaped like an ID1 card, is held in the relevant field, and the field strength is calculated from the induced energy. The coil itself is connected to the measuring system via a cable. This cable connection is disruptive because the reader or card moves mechanically within the production machines. Furthermore, such a measuring system is quite expensive.

[0007] Alternatively, a so-called REF-PICC can be used to measure the electromagnetic field strength. This setup is significantly cheaper than a dedicated measurement system, but also considerably larger than an ID1 card and requires a cable connection to a voltmeter. Therefore, this solution is also unsuitable for adjusting field strengths in production machinery.

[0008] The two methods mentioned are also not suitable for everyday applications between a chip card and a reader.

[0009] The object of the present invention is therefore to improve the communication between a chip card and the reading devices.

[0010] This problem is solved by a method for determining the value of an electromagnetic field strength and a chip card according to the independent claims. Embodiments and further developments of the invention are specified in the dependent claims.

[0011] A method according to the invention for determining a value of an electromagnetic field strength using a chip card comprises the steps of Providing a chip card with a coil and an integrated circuit; calibrating the chip card using different values ​​of an electromagnetic field strength, whereby a power output of the integrated circuit is determined for each specific value of the electromagnetic field strength; creating a correlation between the different values ​​of the electromagnetic field strengths and a corresponding power output of the integrated circuit; applying an electromagnetic field strength of unknown value to the chip card; determining a power output of the integrated circuit; and determining the corresponding value of the electromagnetic field strength using the correlation.

[0012] A fundamental concept of the present invention is the use of a relationship or correlation between the electromagnetic field strength applied to a chip card, in particular the magnetic field strength H, and the power output of the chip card. In this way, for example, the electromagnetic field strength can be precisely determined. The chip card functions as a measuring instrument, thus eliminating the need for special measuring devices.

[0013] Typical electromagnetic field strengths for communication between a chip card and a reader, for example, range between 1.5 A / m and 7.5 A / m. The integrated circuit may, for example, include a processor. The correlation may be represented as a table, matrix, or similar structure.

[0014] The proposed chip module thus offers the advantage that the electromagnetic field strength can be precisely determined using only a chip card. This is particularly useful in moving systems of production machines, as the chip card communicates wirelessly, eliminating the need for a cumbersome cable. The proposed method can also be used for calibrating read heads in production machines. Furthermore, it allows for the determination of electromagnetic field strengths in unknown systems, such as those where the position of the reading coil within the device is unknown.

[0015] It can be implemented that the correlation between different electromagnetic field strength values ​​and the corresponding power output of the integrated circuit is stored on the chip card, and that the corresponding electromagnetic field strength value is output from the chip card to the reader. In this way, the chip card can directly output an absolute field strength value. It is also possible for the chip card to output one or more parameters, such as relative changes or power output of the integrated circuit. Then, based on the correlation, an electromagnetic field strength value can also be determined outside the chip card, for example, in the reader.

[0016] Furthermore, the performance of the integrated circuit can be determined by the amount of work completed over a defined period, the time elapsed for a defined workload, and / or the operating frequency achieved by the integrated circuit. These are examples of measures of the energy consumed by the integrated circuit, or in other words, the energy input into the chip card. The operating frequency, and thus the performance, of the integrated circuit or a processor within the integrated circuit depends directly on the electromagnetic field strength applied to the chip card.

[0017] It can be provided that a reader issues a defined speed test command to the smart card. The use of a speed test command was first described in DE102015004314A1 and has the advantage that a defined command is available and supported by a wide variety of devices, especially production machines. The speed test command can be determined using the carrier frequency of 13.56 MHz. The speed test command can include an adjustable waiting time for the smart card's response. Once the waiting time has elapsed, the smart card can output a calculated result, so that the field strength can be deduced from the result and the waiting time.

[0018] Furthermore, the chip card can be configured to output the power of the integrated circuit and / or the corresponding electromagnetic field strength value in historical bytes of the speed test command in the ATS. This allows values ​​to be easily transferred from the chip card without the need to introduce new commands.

[0019] A disclosed method for coupling a reader and a chip card with a coil and with an integrated circuit comprises the steps of Emitting an electromagnetic field with an electromagnetic field strength by the reader; determining a power of the integrated circuit according to the electromagnetic field strength in the chip card; transmitting a parameter value from the chip card to the reader, wherein the magnitude of the parameter value depends on the determined power; and providing a signal to the reader for improved relative alignment between the reader and the chip card.

[0020] Here, too, the underlying principle is that a relationship or correlation between the electromagnetic field strength applied to a chip card and the chip card's performance is used. In this way, for example, the relative alignment between the reader and the chip card can be improved for optimized communication or coupling.

[0021] When a smart card is used to determine field strength and / or the optimal position on or near an unknown device, the method proposed here can be implemented, for example, in software or an app. This app can feature a graphical interface that allows the user to see the applied field strength as a function of the smart card's position. If the user moves the smart card, the data is displayed graphically in an X / Y plane. Alternatively or additionally, a signal strength bar can also be displayed. The user can then use the card to determine the best possible position on the reader.

[0022] Otherwise, the same advantages and modifications apply as described above.

[0023] The reader may be configured to provide at least one indication of the electromagnetic field strength and / or the position of the chip card. This indication(s) can be displayed visually, for example, such as on the screen of a smartphone or other reader. For instance, the outline of a placement area for the chip card could be displayed. Optical or haptic indications or signals are also possible.

[0024] Furthermore, the reader can be configured to update the information when there is relative movement between the reader and the chip card. In this way, the chip card or the reader can be interactively guided to a position with the best reception. A user can then be guided directly to this position. An automated process is also possible, in which the reader and the chip card communicate repeatedly to determine the optimal position.

[0025] A chip card according to the invention, comprising a coil and an integrated circuit, provides that a correlation between different values ​​of electromagnetic field strengths applied to the chip card and a corresponding power output of the integrated circuit is stored and can be retrieved in the integrated circuit.

[0026] Here too, a fundamental concept of the present invention is that a relationship or correlation between the electromagnetic field strength applied to a chip card and the chip card's power output is used. In this way, the electromagnetic field strength can, for example, be precisely determined. The chip card functions as a measuring instrument, so that no special measuring devices are required. The same advantages and modifications apply as described above.

[0027] The integrated circuit can be configured to determine the power output of the integrated circuit in response to an electromagnetic field emitted by a reader to the chip card, to determine the corresponding value of the electromagnetic field strength using correlation, and to output this value to the reader. In this way, an absolute value of the electromagnetic field strength can be determined directly using only the chip card.

[0028] It may also be provided that at least two coils are used, arranged in different orientations. With this arrangement and / or specific coil geometries, dedicated measurements regarding the coil position of the reader or any irregularities in the reader field can be taken.

[0029] A disclosed reader for a chip card with a coil and an integrated circuit comprises a transmitting antenna configured to emit an electromagnetic field with an electromagnetic field strength to a chip card, a receiving antenna configured to receive a parameter value from the chip card, wherein the magnitude of the parameter value depends on the determined power of the integrated circuit, and a provisioning device configured to provide a signal to the reader for improved relative alignment between the reader and the chip card.

[0030] Here, too, the underlying principle is that a relationship or correlation between the electromagnetic field strength applied to a chip card and the chip card's performance is used. In this way, for example, the relative alignment between the reader and the chip card can be improved for optimized communication or coupling.

[0031] The delivery device can be used to display the signal(s) visually, for example, as on the screen of a smartphone or other reader. For instance, it can display the outline of a placement area for the chip card. Optical or haptic information or signals are also possible.

[0032] One advantage is that different readers can now be configured for a uniform reading field, ensuring that each chip card can expect a defined field strength. Otherwise, the same advantages and modifications apply as previously described.

[0033] The present invention is described below by way of example with reference to the accompanying drawings. These drawings show Fig. 1: a top view of a chip card; Fig. 2: an equivalent circuit diagram of a chip module of the chip card; Fig. 3: a schematic representation of a calibration device for a chip card; Fig. 4: a schematic representation of a reader for a chip card; Fig. 5: a flowchart of a method for determining a value of an electromagnetic field strength using a chip card; and Fig. 6: a flowchart of a method for coupling a reader and a chip card.

[0034] Fig. 1 Figure 1 shows a chip card 10 with a card body 11. The card body 11 can comprise a metallic layer (not shown here), the main surfaces of which can each be covered with a plastic layer. A metallic layer can, for example, be in the form of a core or a layer made of a stainless steel alloy with a thickness of, for example, 400 µm. The thickness of the card body 11 can, for example, be between 50 µm and 920 µm.

[0035] The chip card 10 further comprises a chip module 12, which is inserted into a main surface 13 of the card body 11 or the chip card 10. The chip module 12 can be inserted into a module opening or cavity. The cavity can include a central blind hole and a surrounding rim. Here, the cavity is covered by the inserted chip module 12. The chip module 12 can be glued into the cavity.

[0036] A slot may be provided in the metallic layer, extending from a circumferential surface or an outer edge of the card body 11 to the cavity. The slot serves to prevent short-circuit currents or eddy currents.

[0037] The chip module 12 can include a coil, which may be arranged on a module tape (not shown here). The coil can have approximately 12 to 16 turns arranged concentrically around a chip or electronic circuit of the chip module 12. The width of a turn can be 50 µm to 70 µm, and the distance between two turns can be 100 µm. The copper strands can have a thickness of up to approximately 30 µm. A maximum inductance of 2.5 µH can be achieved with such a coil.

[0038] The chip can, for example, be implemented as an integrated circuit and is attached, for example, in a potting compound to the underside of the chip module 12. The integrated circuit is supplied with energy and / or signals via the coil. In this way, an electromagnetic field can be coupled into the coil. For example, the integrated circuit can be or contain a chip card controller with RFID functionality.

[0039] Fig. 2 Figure 1 shows an equivalent circuit diagram of the chip module 12 of the chip card 10. The chip module 12 comprises the integrated circuit 14, for example, in the form of a chip. The integrated circuit 14 can, for example, be soldered onto the chip module 12 or mounted onto the chip module 12 using flip-chip assembly. The integrated circuit 14 contains a card controller for the chip card 10. The integrated circuit 14 typically includes a processor for executing control functions for the chip card 10, for communication, and for performing arithmetic operations, for example, for security functions. Furthermore, the integrated circuit 14 includes a memory area for storing and / or making data available.

[0040] The integrated circuit 14 also contains a capacitor 15 with a capacitance of, for example, 78 pF. The inductor 16 is connected in parallel to the integrated circuit 14.

[0041] The coil 16 and the capacitor 15 of the integrated circuit 14 form a resonant circuit. This resonant circuit enables the chip module 12 to communicate with an external reader, production machine, or measuring device. The reader supplies energy to the coil 16 via an electromagnetic field, thereby activating and operating the integrated circuit 14.

[0042] The integrated circuit 14 has a processor 17 whose speed depends on the applied field strength. The processor 17 and the integrated circuit 14 start operating at a minimum electromagnetic field strength. As the field strength increases, the operating frequency of the processor 17 and the integrated circuit 14 also increases, and thus the processing speed. This increase can be linear. Beyond a certain frequency threshold, the operating frequency no longer increases. The processor 17 and the integrated circuit 14 are then in saturation and operate at their maximum frequency.

[0043] Thus, a correlation can be established between different values ​​of the electromagnetic field strengths and a corresponding power output of the integrated circuit 14 or the processor 17 contained therein.

[0044] This correlation can be stored in a memory 18 of the integrated circuit 14.

[0045] The chip card 10 can be a D1 card, with a high-quality connection technology between the integrated circuit 14 and the coil 16. Preferably, it is either a soldered connection or a welded connection.

[0046] Furthermore, this chip card 10 can be equipped with an operating system (OS) that includes or supports a speed test command. The speed test command is determined using a carrier frequency of 13.56 MHz. The speed test command can include an adjustable waiting time, for example, in a range of 56 ms to 300 ms, for the chip card 10 to respond. Once the waiting time has elapsed, the chip card 10 can output a calculated result, so that the electromagnetic field strength can be deduced from the result, i.e., the work or power performed by the integrated circuit 14, and the waiting time.

[0047] The speed test command can be implemented such that the result is output to the historical bytes of the ATS. Alternatively, the speed test command can also be used via an additional command that the operating system supports.

[0048] Fig. 3 shows a basic representation of a calibration device 20 for a chip card 10.

[0049] The electromagnetic field strength, here the magnetic field strength H, is first traversed or set via a coil 21 in a range from 0 A / m to 7.5 A / m.

[0050] Once a certain field strength is reached, chip card 10 begins to transmit information, for example, an ATS (Automatic Transfer Signal). Chip card 10 also sends the determined result from the speed test back to the historical bytes in the form of a parameter value 22. This parameter value 22 can include, for example, the processor speed, a unit of time, and / or the number of commands executed.

[0051] These parameter values ​​22 are received by an upper receiving coil 23 and a lower receiving coil 24, then evaluated and stored. In this way, a correlation can be established between the different values ​​of the electromagnetic field strengths and the corresponding power output of the integrated circuit 14.

[0052] For each emitted field strength, a parameter value 22 for the corresponding power of the integrated circuit 14 is recorded, for example, using the speed test command. Since the emitted field strengths are known, a correlation between the different values ​​of the electromagnetic field strengths and the corresponding power of the integrated circuit 14 can be established.

[0053] If this correlation or relationship is established in the calibration device 20, it can be transferred to the chip card 10, for example, via a command. The chip card 10 can then directly output the field strength. Alternatively, an additional external program can perform the conversion to field strength. The correlation can also be established in the chip card 10 itself; in this case, the speed test command or another command will contain information about the value of the respective emitted field strength.

[0054] Once this measurement data has been determined, the chip cards 10 can be directly inserted into the production machines. The chip card 10 now directly transmits the usable field strength back to the production reader at the ATS.

[0055] Fig. 4 Figure 1 shows a basic representation of a reader 30 for a chip card 10. Here, a reader 30 in the form of a smartphone is shown as an example. Other readers, such as permanently installed readers or readers without their own display, can also be used.

[0056] The reader 30 includes a display 31 and a control element 32, for example in the form of a button or an element on a touchscreen.

[0057] The reader 30 has a transmitting antenna 33 for emitting an electromagnetic field with an electromagnetic field strength of to a chip card 10. The transmitting antenna 33 can, for example, be implemented as a coil whose central axis is perpendicular to a surface of the display 31. The operating element 32 can be used to start the process, i.e., the emission of an electromagnetic field with an electromagnetic field strength to a chip card 10.

[0058] The reader 30 also has a receiving antenna 34 for receiving a parameter value from the chip card 10, the magnitude of which depends on the measured power of the integrated circuit 14. The receiving antenna 34 can, for example, be implemented by a coil whose central axis is perpendicular to a surface of the display 31. The transmitting antenna 33 and the receiving antenna 34 can be combined.

[0059] The reader 30 comprises a provisioning device, here in the form of the display 31, configured to provide at least one signal to the reader 30 for improved relative alignment between the reader 30 and the chip card 10.

[0060] For example, the signal can be represented as or encompass a border 35 of a support area for the chip card 10. The border 35 is displayed on the display 31 at the position where the highest or strongest performance of the integrated circuit 14 was determined according to the electromagnetic field strength in the chip card 10.

[0061] Alternatively or additionally, a performance bar 36 can also be displayed on the display 31. The user can then use the chip card 10 to determine the best possible position on the reader 30.

[0062] Fig. 5 shows a flowchart of a procedure for determining a value of an electromagnetic field strength using a chip card 10.

[0063] In a first step 100, a chip card 10 with a coil 16 and an integrated circuit 14 is provided as described above.

[0064] In a second step 110, the chip card 10 is calibrated using different values ​​of an electromagnetic field strength, whereby the power output of the integrated circuit 14 is determined for each specific value of the electromagnetic field strength. For this purpose, a calibration device 20 for a chip card 10 can be used as described in Fig. 3 shown how they will be used.

[0065] In a third step 120, a correlation is created between the different values ​​of the electromagnetic field strengths and a corresponding power output of the integrated circuit 14.

[0066] For each emitted field strength, a parameter value 22 for the corresponding power of the integrated circuit 14 is recorded, for example, using the speed test command. Since the emitted field strengths are known, a correlation between the different values ​​of the electromagnetic field strengths and the corresponding power of the integrated circuit 14 can be established.

[0067] While the first three steps 100 to 120 were, in a sense, preparatory steps for the chip card 10, the following steps are for the actual determination of a value of an electromagnetic field strength using chip card 10.

[0068] In a fourth step (130), an electromagnetic field strength of unknown value is applied to the chip card (10). This electromagnetic field strength is emitted by a reader such as a production machine, a smartphone, an RFID transponder, or similar device. Unlike the first three steps (100 to 120), which take place in a defined test or calibration environment, the subsequent steps occur in an everyday, undefined environment. Therefore, the electromagnetic field strengths are of unknown value.

[0069] In a fifth step 140, the performance of the integrated circuit is determined. This is done analogously to the second step 110 of the calibration process. A defined test or command is executed in the integrated circuit 14, and the performance of the integrated circuit 14 is determined by the amount of work completed within a defined time period, the time elapsed for a defined work period, and / or the operating frequency achieved by the integrated circuit 14.

[0070] In a sixth step, the corresponding electromagnetic field strength is determined using correlation. This can be done by simply retrieving the field strength value for the determined power from the correlation. The correlation can be presented as a table, matrix, or similar format.

[0071] This determination can take place in the reader 30 and / or in the chip card 10. Communication between the two units occurs via wireless near-field communication, ensuring fast and secure data transfer between the reader 30 and the chip card 10. As previously described, a speed test command can be used for communication.

[0072] Thus, the correlation of the different values ​​of the electromagnetic field strengths with a corresponding power of the integrated circuit 14 can be stored in the chip card 10, and the corresponding value of the electromagnetic field strength can be output from the chip card 10 to the reader 30.

[0073] Thus, the absolute value of the electromagnetic field strength can be determined using only the calibrated chip card 10, without the aid of a special measuring device.

[0074] Fig. 6shows a flowchart of a procedure for coupling a reader 30 and a chip card 10.

[0075] In a first step, an electromagnetic field with an electromagnetic field strength of is emitted by the reader 30. This electromagnetic field strength is emitted by a reader such as a production machine, a smartphone, an RFID transponder, or similar device in an everyday, undefined environment. Therefore, the electromagnetic field strength is of unknown value.

[0076] In a second step 210, the power output of the integrated circuit 14 is determined according to the electromagnetic field strength in the chip card 10. A defined test or a defined command is executed in the integrated circuit 14 and the power output of the integrated circuit 14 is determined by a workload completed during a defined time period, a time specification for a completed, defined workload and / or an achieved operating frequency of the integrated circuit 14.

[0077] In a third step 220, a parameter value is transmitted from the chip card 10 to the reader 30, the value of which depends on the measured power. Communication between the two units takes place via contactless near-field communication.

[0078] In a fourth step 230, a signal is provided to the reader 30 for improved relative alignment between the reader 30 and the chip card 10.

[0079] For example, the signal can be represented as or encompass a border 35 of a support area for the chip card 10. The border 35 is displayed on the display 31 at the position where the highest or strongest performance of the integrated circuit 14 was determined according to the electromagnetic field strength in the chip card 10.

[0080] Alternatively or additionally, a performance bar 36 can also be displayed on the display 31. The user can then use the chip card 10 to determine the best possible position on the reader 30.

[0081] Using the methods described here, the chip card 10, and the reader 30, production machines and readers for all types of RFID systems (e.g., wristbands, ID cards, stickers, etc.) can be configured with respect to field strength. A further advantage is that the readers can be set to a uniform reading field, so that the chip cards can expect a defined field strength. This allows for significantly improved data transmission between the chip cards and the reader.

[0082] Furthermore, it is possible to determine the maximum field strength on or at a reader without the user knowing the location of the coil within the reader. This is possible because the chip card 10 acts as a measuring device for the electromagnetic field strength emitted by the reader.

[0083] Determining the maximum field strength in this way allows for optimization of the position of the chip card relative to the reader, thus ensuring maximum energy transfer.

Claims

1. Method for determining a value of an electromagnetic field strength (H) by means of a chip card (10), comprising the steps of: - Providing a chip card (10) having a coil (16) and an integrated circuit (14); characterized in that: - Calibrating the chip card (10) by means of different values of an electromagnetic field strength (H), wherein in each case a performance of the integrated circuit (14) is determined at a specific value of the electromagnetic field strength (H); - Establishing a correlation of the different values of the electromagnetic field strengths with a respective corresponding performance of the integrated circuit (14); - Applying an electromagnetic field strength (H) of unknown value to the chip card (10); - Determining a performance of the integrated circuit (14); and - Determining the value of the electromagnetic field strength (H) corresponding to this performance by means of the correlation.

2. Method according to Claim 1, characterized in that the correlation of the different values of the electromagnetic field strengths with a respective corresponding performance of the integrated circuit (14) is stored in the chip card (10), and in that the corresponding value of the electromagnetic field strength (H) is output from the chip card (10) to the reader (30).

3. Method according to Claim 1 or 2, characterized in that the performance of the integrated circuit (14) is determined by a processed workload during a defined time interval, a time specification for a processed, defined workload, and / or an achieved operating frequency of the integrated circuit (14).

4. Method according to one of Claims 1 to 3, characterized in that a reader (30) issues a defined Speedtest command to the chip card (10).

5. Method according to Claim 4, characterized in that the chip card (10) outputs the performance of the integrated circuit (14) and / or the corresponding value of the electromagnetic field strength (H) in Historical Bytes of the Speedtest command.

6. Chip card (10) having a coil (16) and an integrated circuit (14), characterized in that a correlation of different values of electromagnetic field strengths applied to the chip card (10) with a respective performance of the integrated circuit (14) is stored and retrievable in the integrated circuit (14).

7. Chip card (10) according to Claim 6, characterized in that the integrated circuit (14) is configured to determine a performance of the integrated circuit (14) in response to an electromagnetic field transmitted by a reader (30) to the chip card (10), to determine the value of the electromagnetic field strength (H) corresponding to this performance by means of the correlation, and to output the value to the reader (30).

8. Chip card (10) according to Claim 6 or 7, characterized in that at least two coils are provided which are arranged in different orientations.