DE4031692C1 - Electronic key circuit in contactless chip=card - forms interface working with prim. electronic integrated circuit using interactive coils with ferrite cores buried in substrate - Google Patents

Abstract

A contactless chipcard interface for application in keys which form part of electronic security systems is defined as a key contactless interface (KC1). The latter works in conjunction with a primary electronic IC (PEQ) and the system employs interactive coils wound on ferrite cores embodied in the substrate of the interface which respond to oscillatory signals generated in the primary circuitry (PEQ). Coded data are stored in a memory unit (DR1) - typically an EEPROM - and data transfer from the interface to the prim. I.C. is based on amplitude modulation whilst reverse data transfer employs phase modulation. USE/ADVANTAGE - Card fully compatible with existing types of electronic lock. Card design follows format of large scale IC mfr. and, together with size reduction of chip surface for key applications, reduces cost.

Description

Using the patent specification DE 34 47 560 C2 Chips (commercially available with CCI for Contactless Chipcard Interface inscribed, see electronics, 1987, issue 4, page 14, here abbreviated CI) by well-known European Chip manufacturers manufactured and in chip cards but also in Car keys used. The price of these chips is determined by three reasons are greatly reduced:

• - By large quantities, since the same chip in both chip cards can also be used in the car key.
• - The reduction of the chip area by reducing the conductors web width.
• - Great competition because of the patented circuit requirements can be fulfilled by all leading semiconductor manufacturers worldwide are.

Chips can also benefit from the fall in prices of the CI’s built into conventional keys (e.g. under the trade name men IKOTRON) and are available on the market.

The object of the invention is the CI in its price value form as chip card CI also as key IC (here KCI for Key Contactless Interface), especially in the IKOTRON put. This requires the CI as a KCI with a Limited function coil, d. H. without phase modulation maintain. In addition, there is the task of the KCI compatible with the existing systems on the market design. This means in particular that around a ferrite the coil wound in the key is said to be spirally in one Replace level coils of the chip card solution so that egg existing lock electronics can still be used can and in addition the CI all requirements in the same  Way, as the existing key electronics ge ensure.

The three main tasks of a CI are

• 1. It is the one of a component (PEQ = primary electronics) using an oscillator via two primary coils Transformer principle provided energy (voltage and current) processed via secondary coils in the CI so that usual IC circuits, especially also memory modules (e.g. EE- PROMS) are provided by the CI to fulfill their function.
• 2. The CI carries load on one or both secondary coils Changes depending on the content of the memory by which detectable as impedance changes on the primary side in the PEQ are. It is data transfer from CI to PEQ in the form an amplitude modulation.
• 3. The CI detects a phase shift between the two Vibrations which are generated in the PEQ and over the Spu len are coupled to the CI. It is data transfer from PEQ to CI in the form of phase modulation.

Description of the patented solution

CI's are used for the use of contactless working chip cards, which are supplied via two spirally arranged coils L 1 and L 3 in one plane. Coils and chips are invisibly welded into chip card material and comply with the international ISO standards for chip cards as they exist for contact cards (e.g. telephone cards).

Electronic keys, which also work without contact, contain only one coil in the back of the key and only provide data on the lock via an inductively transmitted signal. Except for the changed th connection between the contact fields L 3 to K 2 and the contacts of a coil, all facilities of the CI remain in use as KCI from rectification GL 1 , GL 2 to evaluation of the signals in component DR 1 as well get how the Ausungs extension of signals via D 1 , D 2 and load change of the coil L 3 via S 1 , S 2 . According to the patent description, it is possible to connect the four contact connections ( FIG. 1, K 1 to K 4 ) for two spiral coils L 1 , L 2 to the two connections of a key coil L 3 . This contacting supplies the two rectifier components GL 1 , GL 2 with alternating voltage and contributes equally to the voltage and power supply in the KCI. The type of energy feed is increased via both rectifiers. The signal lines coming from the components GL 1 , GL 2 transmit the vibration present at the inputs K 1 to K 4 and, when two coils are present, are suitable for indicating the phase relationship of the vibrations on the coils to one another. In the case of the description according to the patent, no phase jumps can be indicated via a coil by comparison between vibrations of two coils. Depending on the selected contacting of the vibration fed via K 1 to K 4 into GL 1 , GL 2 , a phase difference of 0 degrees or 90 degrees is indicated in DR 1 at the inputs L 2 D, L 1 D instead. The absence or constant of a phase difference depending on the contact is used according to the patent by evaluating the two signal branches L 2 D and L 1 D to indicate the absence of a second coil in the KCI. With the indexing of the number of coils, the function is determined independently as a CI or as a KCI. After this determination, the KCI determines its further mode of operation by calling up the information stored in the memory in the same way that it has to be the case with keys in order to ensure compatibility with existing systems. For this purpose, the codes compatible with the keys in use can be present in non-erasable memories directly in the component DR 1 or are contained separately therefrom in the component CAK ( FIG. 2). The code can be output via the same outputs D 1 , D 2 , as is the case when used as a CI for chip cards. The wiring of D 1 , D 2 is determined by the type of contacting of the coil L 3 and has the purpose of relieving or relieving the potential difference (UV to GND) generated by the parts GL 1 , GL 2 , which results from the current change leads in the coil L 3 to detectable signals in the primary coil on the PEQ side. The signal spacing and the signal duration on the lines D 2 , D 1 are in the same way as is the case with existing key lock systems used in the market.

In summary, the automatic selection of the Working as a CI or KCI enables the same semiconductor manufacture for both applications. The different out key or chip card signals are sent by Activate different programs and use others Memory or memory contents in which memory information is stored according to chip card or key requirements.

The claim 2 describes how, according to the patent, free contact fields can be used for bonding two chips before the bonding process in order to burn in the codes required for a key and determined by market introduction in the phase, since the chips are in a form typical for chip card production. The high programming voltages required can easily be provided by external sources in this manufacturing phase and do not destroy the parts that are sensitive to current and voltage. Usable here is the type of application of the chips on film in a form known as film and used in chip cards. Since the spiral coils are applied directly to these foils in the form of conventional conductor track technology, there must be bond points for contact between the chip and the coil. In addition, test contacts are kept free to jointly test the function of the chip and coil after bonding. It is therefore possible with little additional effort to provide contact points in the version for chip cards already for use as a key circuit and to enable the later placement of the memory chip CAK. The contacts (e.g. K 10 to K 14 ) that are not used or used differently in chip card applications can be used with the memory module contacts K 10 to KX when used as a key component KCI. Accordingly, chip card chips CI and key chips KCI can be produced in the same way using the same production process.

Claim 3 solves the problem, such as those preferred for chip cards EEPROMS for storing codes as changeable Read-write memory for key purposes over the time of your practice storage immutability can also be used. EEPROMS in particular are subject to an "aging" by individual bits of their memory content after about 10 years with a lose statistical probability. The problem solving is achieved by the KCI automatically multiplied in the memory. Is the code for the first time and multiplied in memory, the supply via the contact connections according to the description of the claim two can be done is a code refresh to renew the Stopping time from the outside, however, due to the missing second coil not possible when using the key. For this reason a renewal by the KCI automatically with each use leads. Despite these measures, there is still a slight Un security regarding the correspondence of the data stored in the memory put codes. The keys in question send their code with activation incessantly as a signal sequence of an oscillation in the MHz range. Conventional keys use the same code sent from a memory cell repeatedly. With the pa The solution according to the tent will be memory contents of different cells len where the same code is located. On the part of the Receiver (PEQ) are extremely sensitive facilities and Ver drive available, which react to incorrect sequences and the ge  refuse to open or close a lock. Should a BIT in the sequence change from the previous sequence be what can only be the case if a memory cell is defective is because the code is automatically overwritten in the memory a lock or opening on the lock becomes automatic locked out.

The probability that there are different memory cells change at the same bit positions is small. Therefore, at multiple filing of the KCI automatically a plausibility check tion according to the unchanged bit's in different Spei make. Is no match different Memory cells recognizable for the KCI, the memory itself actively be assigned a code that is a compulsory invalid action on the lock side. The change of key-typical pulse pattern of bit spacing, bit group spacing certainly leads to rejection on the part of the castle.

Claim 4 describes how information is to be transmitted from the lock to the key by means of a coil. Primary-side (PEQ) vibration changes or coil changes are generated as causes for voltage swings or voltage drops on the KCI side. According to patent DE 34 02 737 C1, these are recognizable if the duration of the influence is short compared to the times of the unaffected function. In these cases, a sufficiently large voltage difference between the averaged long-term voltage and the instantaneous voltage drop or voltage swing can be determined. According to the patent, it is stated how the two capacitors C 1 , C 2 by decoupling z. B. by DIODE DI, keep their charge separately and thus the different discharge times due to different capacities of the capacitors are of different lengths. A short voltage swing or a break is thus detectable in a detector circuit DTU. This method in turn utilizes the circuit structure of a two-coil system with two decoupled rectifiers GL 1 , GL 2 (DIODE COUPLING). Due to the double voltage generation, one system for short-term and one system for long-term voltage stabilization is available. The evaluation of a change in the output power on the primary side is thus detectable, since one rectifier can serve as a reference for the other, since the change in power on the primary side results in voltage changes under load, which is always given by the circuit. Such voltage changes can be produced by various known measures on the part of the PEQ. They have in common that the energy (power) transmitted per time (vibration) is changed and consequently voltage changes can be detected on the secondary side. Since the information delivery by means of loading or unloading changes via the switches S 1 , S 2 also leads to voltage changes, a temporal synchronization of the events for reception and transmission is additionally required. This can be done by a method as described by DE 31 49 789 C1, which is used here on the key side in addition to the transmission method. Synchronization can be established by frequency counting, in which the transmission from the lock to the key takes place at times (frequency counter events), since no time window is provided for the transmission from the key to the lock.

Claim 5 uses the existing coils or connections radiate unnecessary performance. Because of close coupling and coils with ferrite core in the key and high in the lock Power transmission available in the installed systems which does not change when new key electronics are used part of the power on the chip is heatable changes. The heat output per time for chips is proportional to Chip area. Chip area is increased due to cost and manufacturing reasons reduced in the future. So there is the problem of chip overheating and chip destruction. The coil present on the film can be di can be used directly, making it a very inexpensive solution is enough or an additional coil is connected.

Claims (5)

1. The use of contactless interface circuits (with CI designated net) as they come in smart card applications having two coils L 1, L 2 used in electronic keys, such as are used with a coil L 3, characterized in that
the one, a ferrite-wrapping coil L 3 of a key with its two contact-making winding ends LA, LB all four contacts K 1 , K 2 , K 3 , K 4 , of an electronic component, which as contacts for two lying in one plane, spiral Coils L 1 , L 2 of a chip card are provided and are not connected to them, contacted in such a way
that in a first contact type LA with K 1 , K 3 and LB with K 2 , K 4 and in a second contact type LA with K 1 , K 4 and LB with K 2 , K 3 and the contacts K 1 , K 2 , K 3 , K 4 rectifier circuits GL 1 , GL 2 are supplied, which forward the vibrations supplied via the coils L 1 and L 2 or L 3 via outputs L 2 D, L 1 D to a component DR 1 , which the Phase position of two vibrations at the inputs L 2 D, L 1 D in particular has to test a phase shift as a phase shift, as it is generated between the coils L 1 and L 2 due to the control via primary coils, in order to activate the CI from the phase position electronically to index the coil L 1 or L 2 , which is used to transmit the phase jumps as an information transmission path from a transmitter coil to the CI,
whereby at the same time the second coil is determined, via which information is preferably sent from the CI to receiver coils by loading or unloading, so that an alternating bidirectional information transmission is ensured, no phase shift in the component DR 1 being detectable when using the first contact type and in the second contact type a constant phase shift occurs and this phase position, electronically evaluated in the component DR 1 according to size (phase angle) and duration (time or number of oscillations in which there is no reset of the phase position), determines that it about the use of a coil L 3 instead of two coils L 1 , L 2 and to be transferred loading or unloading changes of the coil L 3 in the same way as with existing keys for the sake of compatibility with imported systems, which can be done by calling up an im Component DR 1 present program (micro program) succeed n can, the codes in a memory being used as electronic key codings, which are present in the component DR 1 or outside DR 1 in a code array (denoted CA), executed for example in the form of indelible memories such as ROMs, diode arrays Gate arrays with burnable gate elements and this code via both outputs D 2 , D 1 or optionally via an output, for example D 2 electronic switches S 1 , S 2 , which is the DC voltage potential between UV generated in GL 1 , GL 2 and GND load or unload, which means that there are shunt loads or reliefs parallel to the coil L 3 via GL 1 , GL 2 and the component KCI is comparable to electronic keys, in which load changes on the coil L 3 lead to demonstrable impedance changes on the other side the inductive coupling and can be used for information transmission, making the CI compatible as key electronics is. 2. Interface circuits according to claim 1, characterized in that the component KCI is constructed separately from a memory component and part of the contacts K 1 , K 2 to KX, where KX denotes the contact with the highest number in a counting order, are intended to be one to apply external programming voltage to the component CAK in order to blow elements of the component CAK for coding purposes with a higher voltage than is possible with the maximum supply voltage UV and the maximum current, which are available via the component KCI and can be transmitted via a coil L 3 are that this component CAK has received its coding by means of a spatially and temporally separate structure, independent of the neighboring structure with the component KCI on a film, and thus a solid, indelible code, as required for keys, is placed next to the component KCI and after electrical contacting, the component KCI sends a code to a Sp owl can transmit. 3. Interface circuit according to claim 1 and 2, characterized in that the encodings in a read-write memory (LSp) of the component les CI or in the component CAK in a long-term variable form, for example in an EEPROM and thus not sufficient for data security requirements in a key , the component CI, based on its function, indicates a mode of operation with only one coil and, based on an integrated, hard-wired program, stores a code that was initially written for the first time immediately, automatically multiplied in the LSp and repeats this automatically with each use, so that the storage time changes with each use renewed and additionally the code retrieval repeated sequentially from different cells of the memory for transmission via the coil L 3 according to the method described in claim 1, and thus an additional security is given, if a memory content deviates a sequential Transmission of different repetition sequences is delivered, which, when evaluating the load changes via L 3 on the part (PEQ) that contains the primary coil or coils, rejects the transmission as non-identical repetitive, with an additional automatic check of the stored codes in the LSp in the way he can follow that matching codings are rated as correct due to the considerably lower likelihood of a random error matching at certain points in their code length and those that do not match are rated as incorrect and are overwritten as correct and are overwritten in the different code, additionally the memory is automatically filled with incorrect information, unless there is no clearly the same code several times in the memory, whereby the uniform typical code pattern, as defined for the respective key generation, can be changed in a defined manner nn, so that a random match with existing codes is excluded, whereby the combination of the above measures ensures comparable security of the codes stored in LSp with those stored in indelible memories, thus meeting the requirements of electronic keys. 4. Interface circuit according to claim 1 to 3, characterized in that the primary coil required for energy transmission on the PEQ side in their oscillation phase jumps or another type of coils or vibration influencing, for example frequency change or amplitude change, which in the primary coil, for example, a reduced or increased Energy output during the time (number of vibrations) until the changed phase position or oscillation or coil change stabilizes and this reduced or increased energy output leads to voltage reduction or voltage swing on the part of the KCI part, which when comparing the two separate voltages via C 1 and C 2 are detectable, if z. B. C 1 is much larger than C 2 and thus short-term drops in C 2 lead to a change more quickly C 1 is separated from C 2 by, for example, a blocking diode (DI), so that no charge coupling and capacitance coupling of the capacitors can take place, a blocking diode DI lies directly between the capacitor and the UV line, with which the voltage gap or dips in a detector circuit DTU as a difference between long-term voltage behavior in the C 1 branch to short-term voltage behavior in the C 2 branch or vice versa can be demonstrated on the key side instead of on the lock side and additionally the first and all subsequent phase jumps, oscillation changes or coil changes to counter events take place, which can take place by counting the amplitude changes or another characteristic oscillation state on the part of the PEQ part and on the part of the KCI part, and thus synchronized, with which also in the case of changes When the frequency is synchronized, the points in time at which a phase jump can take place are achieved, these points in time expediently being in the middle of the distance between two loading or unloading changes which are transmitted via S 1 , S 2 - and thus also the transmission of information is guaranteed with a coil by a chip, which is used with two coils for chip cards and additionally enables the requirements of an electronic key with a coil. 5. Interface circuit according to claims 1 to 4, characterized in that an excessive power coupling of the primary side PEQ to the KCI is reduced with a key due to the technical design of the existing installed systems in that one of the coils L 1 , L 2 is used for power radiation on the KCI side and for this purpose the connections K 1 , K 2 , K 3 , K 4 are used, one of the two spirally wound coils L 1 , L 2 originally present on the film being retained and a circuit coupling between the coil L 3 receiving the active power and a power radiating coil L 1 or L 2 is produced or a suitably dimensioned coil is used instead of the coils L 1 or L 3 and this limited radiation output increases the KCI's power output due to heat generation.