EP0118884B1 - Device at locks - Google Patents

Abstract

PCT No. PCT/DE84/00045 Sec. 371 Date Nov. 1, 1984 Sec. 102(e) Date Nov. 1, 1984 PCT Filed Mar. 8, 1984 PCT Pub. No. WO84/03533 PCT Pub. Date Sep. 13, 1984.Safety mechanism for locks (electronic lock) comprising a pick-up performing the function of a key and a sensor performing the function of a lock part. The pick-up is provided with a pre-determined surface arrangement of magnetically permeable, preferably inactive material in the form of soft-iron pins forming exciting elements, which forms a code. For detecting the code of the pick-up, the sensor is provided with an arrangement of sensor elements in a surface matrix of the same geometrical extension, which sensor elements can be varied as to their ohmic resistance by a change in the distribution of the magnetic field lines and take the form of magnetically controllable magneto-resistors. The magneto-resistors are set up, preferably, in the manner of an integrated circuit. The magneto-resistors are followed by comparators which are suitably wired to store the code word in an unerasable manner and which in the presence of a correct pick-up code assume an output potential driving an evaluator circuit connected to its output to release a locking mechanism.

Description

The invention is based on a device according to the preamble of claim 1. In a known device of this type (Wo-A-8102 603) an electrical supply energy for a circuit-generating generator is provided in an electronic door lock, which is activated by a door latch at the moment biased spring is driven and releases a predetermined amount of electrical energy and an evaluation circuit for decoding a magnetic encoder.

The decryption device is constructed in a matrix-like manner and comprises a multiplicity of Hall generators which generate a certain logic output signal at some of their outputs when a magnetic south pole is nearby and at the same time supply voltage is applied to input connections, or which generate another logic output signal when there is a magnetic north pole in their vicinity and the supply voltage generated by the electrical generator is also supplied to the input terminals.

Therefore, the transmitter comprises a key card, which has distributed magnets and which is to be inserted into a slot, so that there is a certain magnetic distribution adjacent to the Hall generators. The various outputs of the Hall generators are then connected to a downstream digital comparator.

The problem with such an electronic lock is that the Hall generators used have a total of four connections and are arranged in rows and columns with one another, the possible packing density of Hall generators playing a significant role. These must be arranged in such a way that on the one hand there is a sufficiently strong magnetic field strength for a reading, but on the other hand no effects at least on the immediate neighboring elements may occur.

In the known electronic lock, read-out is therefore stationary, since the Hall generators can show a differential voltage transverse to the magnetic field when the voltage is applied, which, as mentioned, is pole-oriented. The reading is carried out by successive, i.e. serial, application of certain columns of Hall generators with a supply signal, reading out the respective word generated overall from the logical states of each individual Hall generator, storing and identifying the word and then reading out the next Hall generator. Column. This is cumbersome and does not take into account the possibility that when a magnetic encoder approaches a magnetic sensor, there are always transient or transient processes that can be sensibly captured and evaluated by dynamic reading based on a digital pulse reading.

It is also known to use a special resistance structure in a device for generating an output signal in the presence of a magnetic field, in which loops of magnetoresistive materials which are perpendicular to one another are arranged. By assigning a constant bias magnet, a specific magnet distribution and thus resistance position is generated in this, due to the formation of loops in the rest of the particularly extensive magnetoresistive resistance element. The action of a further magnet then results in a different polarization of the magnetic field distribution and finally a signal generated by the geometric resistance arrangement at the output.

Although this publication contains the basic idea, magnetoresistive elements for the coding of identity cards and the like. to be used, wherein five different magnetic resistive elements are used, which form serially operating scanning elements for dynamically moving cards passed by them. These cards have a distribution of magnetically permeable pieces in columns and rows, so that the overall polarization of the magnetic field changes and the presence of the magnetic pieces can be detected (FR-A-2 296 182).

Finally, it is known (US-A-4 354 189) to use a donor in the form of a finger ring for the coding circuits, whereby a multitude of possibilities are given for how such a small annular donor element carried on a user's finger can be used for a specific one Opening code or the like to use. However, this publication does not contain any suggestions for working with a surface-active, selective magnetic action in such a narrow space, because the possibility of isolating adjacent neighboring elements from magnetic action but addressing the desired element has not been recognized.

In general, security systems are known which are able to distinguish between authorized and unauthorized access to buildings, cars and the like. to distinguish between those that can prevent the taking away of an object and / or that are suitable for the simultaneous arming and disarming of alarm systems; namely in a variety of forms, starting with the usual beard keys, especially in the form of a cylinder lock, to the electronic locks already mentioned, which work by entering and evaluating predetermined codes.

The known systems, in particular of the electronic lock structure, which are briefly explained below, therefore represent only a selection.

In order to release a lock in an access control or the like in a known key lock. to reach, a multi-digit number must be entered, after which the lock is released in the correct order in the correct order. Is problematic Here, companions watch the key number being keyed in and can remember this number. It can also be problematic that a multi-digit number can be forgotten, especially in stressful situations, or it is accidentally keyed in incorrectly, which can have the disadvantage that, in addition to the fact that the lock is not released, the subsequent entry of the correct number may be blocked for a predetermined period of time if the system is equipped in such a way that you want to effectively prevent trying out the key number. In any case, it is customary to write down the key number in the key lock in some way, so that the physical availability of the code is usually given. Finally, such a keyboard must have a certain minimum size and be adequately protected against environmental influences, so that such a key lock is essentially suitable for use in closed rooms.

In the known magnetic card lock, a card which contains a magnetically written carrier is inserted into a reading device for actuation. The information of the carrier strip is read out and, if this is in agreement with a stored code information, it is triggered by the circuit. Such a magnetic card lock corresponds approximately to the subject of Wo-A-8 102 603 already mentioned at the beginning.

With such a magnetic card lock, the relatively high outlay for the reading device, which usually must have an electromechanical drive, and the easy deletion of the information can also be disadvantageous. It is enough to bring such a card close to strong electromagnetic fields or to put it there in order to erase the label. The required field strengths are achieved, for example, by loudspeakers and radio network transformers. It could also be problematic that the access of the card to the reading device cannot be protected against environmental influences, so that an application is mainly useful in closed rooms, as well as the fact that the magnetic information can easily be changed and therefore just as easily duplicated .

Locks that work with inductively scannable cards are closely related to such magnetic card locks. The operation is similar to the magnetic card lock - the code carrier has a continuous metal foil in the middle of the card, the surface of which is divided into quadrants. if you pass this film past inductive read heads, you can determine which quadrant contains a hole and which does not. This binary information represents the coding, which is compared with a permanently stored coding. The main disadvantage of this inductively scannable card is the fact that an electromagnetic drive is again required and the associated disadvantages with regard to sensitivity to environmental influences and operational reliability. The property that the digitally available information can be processed by computers or microprocessors could be assessed as an advantage of the inductively scannable card.

Finally, it is possible to provide a so-called electronic contact lock, in which the key and lock contain identical resistance networks, with a predetermined number of nodes that can be tapped. Corresponding plated-through holes can be used to select nodes and assign them to the contacts of the key, so that coding can be achieved. The contact to the key is implemented as a sensor contact because the contact strip required to scan the key may only carry potential during the active phase. When the key is placed on a contact bar, the lock is activated via a sensor bar and the coding of the two networks is compared. If there is agreement over a predetermined period of time, the circuit is triggered. The main disadvantage of such an electronic contact lock is the required contacts and the relatively complicated key to be produced. Due to contact uncertainties that cannot be ruled out, double actuation may be necessary. In particular, it cannot be avoided for long periods that the contact strip becomes dirty and errors are introduced.

Finally, it is also known to arrange a coding arranged on a card in the form of opaque or transparent cutouts which form data or clock tracks, which coding can then be detected by the reading device on an infrared basis and compared with the stored, applicable code. If the reading is to take place without a motorized retraction, special measures must be taken to avoid misinterpretation of the code in the event of an arbitrary card insertion.

The invention has for its object to provide an electronic lock, the code transfer achieved by magnetic action in a small space, but can be done with high security and without the possibility that the respective code is accessible to unauthorized persons.

Advantages of the invention

The invention solves this problem with the characterizing features of claim 1 and, through the use of sensor elements that can be influenced only by their resistive value by means of a selective magnetic action, arranged in the highest packing density in the manner of a surface matrix, has the advantage that with complete independence No mechanically moving parts are required due to environmental influences, i.e. there is no wearable mechanical drive.

On the other hand, the device according to the invention works with binary data and is therefore also used for evaluation with process computers, microprocessors and the like. compatible. It is advantageous that the output signal changes required for decoding the key code occur simultaneously, i.e. in parallel, and are also generated by a stationary and simultaneous action by the transmitter element, but on the other hand the whole process is dynamized in that the coupling resulting from the changes in resistance resulting voltage changes to downstream comparators via capacitors.

Advantageous developments and improvements of the invention are possible through the measures listed in the subclaims. The design of the encoder is particularly advantageous not in the form of specially acting magnets, but as a structure of soft iron pieces or pins, which are introduced to each magnetically sensitive element in the sensor, namely field plate resistance, in such a way that its magnetic flux, generated jointly by a single one Bias magnet, so strongly influenced, namely changed, that there are suitable output voltage jumps for code evaluation. These voltage jumps then arrive at the inputs of the downstream comparators via respectively assigned RC elements with a sufficiently large time constant, so that there is a parallel image of the respective identification code that can be evaluated.

The variable ohmic resistance field plates are known per se and their effects are described, for example, in the book “Transistor-Handbuch” by Jan Hendrik Jansen, 1980, Franzis-Verlag GmbH, Munich, pages 134, 135.

It is also advantageous that the encoder fulfilling the key function in the present invention has a coding that cannot be detected or can only be detected with an extraordinarily high outlay, the actuation of a lock or a lock being able to be carried out completely openly via the sensor, since only the Needs to coincide with the sensor surface. The dimensions of the complementary sensor and sensor surfaces that form surface matrices are so small that the sensor can, for example, be easily installed or arranged in the surface of a ring or the like, so that the lock can be actuated easily by moving the ring in a corresponding recess in the sensor area of the lock or presses there. The coding of the key (encoder) is also unknown to the user or is of no interest. The key can also be borrowed without further ado, since replication is practically impossible.

The operational security of the security device according to the invention is absolute, since no active elements or systems are arranged in the area of the key or transmitter - only and preferably in a certain surface matrix distribution, soft magnetic elements, partial areas or pins, and the sensor against any aging, against drift influences or other disturbances can be secured by a sensible electronic circuit.

The resistors, which are preferably arranged in the form of a surface matrix and which can be provided in the sensor in virtually any number and distribution, are preferably produced by the customary etching and other processing techniques, such as are used in integrated or highly integrated electrical circuits, for example by corresponding ones Doping silicon substrates with antimony or other contaminants in such a way that these field plate “resistors” change their resistance value depending on the course of the magnetic field lines crossing them.

Another advantage is the common bias of all operational amplifiers or comparators connected downstream of the individual field plates by means of a single voltage divider at their two inputs, as a result of which they assume a defined state when the bias is secure - this means that the offset voltage remains the same for all operational amplifiers, with an additional one then of the inputs of each operational amplifier via a capacitor which is coupled in as a result of the change in resistance when the transmitter activates the voltage jump. The time constant for this process is preferably around 1 second, so that on the one hand there is sufficient time to effectively prevent a possible detection of the code by simply trying it out, on the other hand it is ensured that the cancellation of the DC coupling caused by the capacitor after this has expired Time constant is undone.

• Fig. 1 eine Draufsicht auf den Sensor im Schnitt, aus welcher die Oberflächenverteilung der magnetisch steuerbaren Widerstände sowie die Leitungsintegration erkennbar ist;
• Fig. 2 eine Draufsicht auf eine mögliche Ausbildung des Oberflächenbereichs des Sensors, wobei innerhalb des Ovals die magnetisch steuerbaren Feldplatten/Widerstände in beliebiger Anordnung als Oberflächenmatrix liegen können;
• Fig. 3 einen Schnitt durch den Sensor der Fig. 2, so dass man erkennt, dass sich zum Einsetzen etwa eines vorspringenden Geberbereichs mit der Geber_-Oberflächenmatrix eine entsprechende Absenkung zur geführten Aufnahme am Sensor ergibt;
• Fig. 4 zeigt schematisch und in vergrösserter Darstellung einen dem ovalen Ausschnitt des Sensors entsprechenden, ovalen Bereich am Geber, wobei die kleinen Kreise eine willkürliche Verteilung von eine vorgegebene magnetische Permeabilität aufweisenden Geberelementen darstellen, die Stifte sein können und die magnetische Durchflutung im Sensorbereich entsprechend selektiv beeinflussen, und
• Fig. 5 eine bevorzugte Ausführungsform des Sensors im elektronischen Schaltungsbereich, wobei, soweit zum Verständnis erforderlich, auch diskrete Schaltungselemente angegeben sind.

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

• Figure 1 is a plan view of the sensor in section, from which the surface distribution of the magnetically controllable resistors and the line integration can be seen.
• 2 shows a plan view of a possible configuration of the surface area of the sensor, the magnetically controllable field plates / resistors being able to lie in any arrangement as a surface matrix within the oval;
• . Fig. 3 is a section through the sensor of Figure 2 so that it can be seen that for insertion as a projecting portion with the donor donors _- surface matrix is a corresponding decrease for guided reception results at the sensor;
• FIG. 4 shows schematically and in an enlarged view an oval area on the transmitter corresponding to the oval section of the sensor, the small circles being an arbitrary distribution Representation of a predetermined magnetic permeability having encoder elements that can be pins and accordingly selectively influence the magnetic flow in the sensor area, and
• 5 shows a preferred embodiment of the sensor in the electronic circuit area, discrete circuit elements also being specified, insofar as this is necessary for understanding.

Description of the embodiments

It is initially pointed out that the embodiment shown is merely a preferred embodiment for better understanding of the invention and does not restrict it - in particular, in this embodiment the coding is carried out in the sensor behind the operational amplifier area and a diode matrix is used for decoding , not seen a restriction of the subject matter of the invention to this possibility - it goes without saying that, by appropriate wiring of the operational amplifiers, the coding can also be carried out in front of them and their rear outputs can then only work, as is only indicated, on a common resistor that then raised to a certain voltage.

There are many possible uses for the security device according to the invention - for example, it can be used in locking systems for houses and buildings, in locking systems with remote access and free coding, in security systems with remotely switchable code, security devices for devices and machines, in locks on motor vehicles and the like ., for alarm systems, for bank lockers, for safe locks and the like, to name just a few of the possible applications.

The invention is composed of a transmitter that performs a key function, and a sensor, it takes over the corresponding lock functions and, when identifying identical codes in the transmitter and in the sensor, releases corresponding interlocks or carries out circuits that serve to identify persons, access to certain means open or used to switch alarm systems or the like.

In Fig. 1, the representation of the surface area of the sensor 1 is given in a greatly enlarged form, which has a suitable housing 3, which can vary depending on the installation location and use function. The housing has a front, suitably designed contact surface, beneath which or immediately adjacent to it are the multiplicity of individual, magnetically controllable sensor elements or resistors 6. The respective connection points of these resistors are connected in a suitable manner to outer contact connections 8 and 8 ′. It has already been pointed out earlier that this area of the sensor with the magnetically controllable resistors 6 and their cabling 7 can be constructed using integrated circuit technology, so that the smallest dimensions can be achieved in a suitable manner with high precision in function and design. The individual sensor elements, magnetically controllable resistors or field plates are then connected to a downstream evaluation circuit via the connection contacts 8, 8 ', which will be discussed in more detail below in connection with the illustration in FIG. 5.

Furthermore, in the illustrated embodiment, a magnetic biasing element (not shown) is provided adjacent to and acting on all resistors 6, as will be referred to in the following in the desired manner, which can be, for example, an electric or permanent magnet and which is in the idle state of the Systems assigns a predetermined magnetic field intensity to the individual resistors 6 in such a way that a specific resistance value results from them, which results from the number of magnetic force lines crossing or acting on the field plate resistors 6.

The security system is then further constructed in such a way that magnetically effective means are provided or not provided in the area of the transmitter in the same spatial and spatial distribution as the field plate resistors 6, which are preferably arranged here in the manner of a surface matrix, which, when the transmitter with its effective surface is placed on the receiver-sensitive surface of the sensor, selectively change the magnetic flux of certain field plate resistors 6 (namely by their presence) or not change - if no such element is present at this point. A preferred exemplary embodiment uses small or smallest soft iron elements for the assigned transmitter surface where a change in the resistance value of the resistors 6 is to take place after the coding has been made and can provide elements or bodies at the other locations which have no magnetic effect on the outside, i.e. dia - or are paramagnetic. Such elements, which selectively influence the magnetic field line distribution prevailing in the area of certain field plate resistors 6, can be soft magnetic pins 9, the end regions of which change the magnetic field distribution prevailing in the sensor surface when the sensor surface rests on the sensor surface.

The end result is an evaluation circuit for the field plate resistors 6 for the sensor, as shown in FIG. 5, it being understood that the circuit shown there made of discrete circuit elements represents only one of the possibilities, such as the relative displacements in FIG the field plate resistors 6 can be detected and evaluated - this applies in particular to the further processing of the output signals of the operational amplifiers to which the field plate resistors are connected. To the For better understanding, some polarities are also given in the circuit of FIG. 5; it can be seen that the field plate resistors 6 are connected via respective series resistors 10 between the positive supply voltage (+ U _B ) and ground. As a result of the assignment of a magnetic bias generator, which subjects the resistors 6 to a preferably homogeneous magnetic field of a predetermined strength, the individual resistors 6 have certain, preferably identical, resistance values in the idle state, although this is not critical, since they have a direct current compared to the comparators / Operational amplifiers are decoupled.

An essential inventive feature is that for evaluating the selective change in resistance in the intended operative connection between the transmitter and the sensor, the individual resistors 6 are connected downstream as comparators, operational amplifiers, both inputs of which are biased by the same voltage divider. This voltage divider consists of the series connection of three resistors 13a, 13b and 13c, the middle resistor 13b being connected to all inputs (minus inputs or inverting inputs or plus inputs or non-inverting inputs) of all comparators or comparators 12 due to the voltage drop generated thereon is. In a preferred embodiment, this mean bias resistance 13b is relatively low-resistance and can, for example, have a numerical value of only 10 ohms, so that, of course, matched to the respective supply voltages, a drop in the bias voltage difference of 10 mV results here, which is slightly greater than is the offset voltage of the operational amplifier. In this way, stable, defined states of the operational amplifiers are achieved for the idle state. This offset resistor 13b thus specifies a stable initial state, since the offset voltage always remains the same.

The respective field plate resistors 6 are then connected from the connection points with their correspondingly assigned series resistors via capacitors 16 to the non-inverting inputs of the operational amplifiers.

The outputs of the operational amplifiers are then connected to a diode matrix 15 for decoding, consisting of respectively polarized diodes 15a and 15b, which in turn are then connected to different, common potential rails 25 and 26, respectively.

From here, in any case, for example from the outputs of the operational amplifiers, the further decryption can also be carried out in a different way - for example, it is possible to design a microprocessor or computer in a corresponding manner so that it quickly queries the outputs of the individual operational amplifiers and with them compares a corresponding code word and, if they match, performs circuits, releases interlocks or the like.

The following explanation of the special evaluation circuit is therefore optional and only preferred as an exemplary embodiment.

For a better understanding, it makes sense to designate the comparator output rail 25 as a so-called H-rail (from high = high in potential), while the other potential rail 26 can be referred to as a so-called L-rail (from low = low in potential or at ground potential).

The interconnection of these rails 25, 26 with the outputs of the operational amplifiers is, of course, completely different according to the respective code and, in the exemplary embodiment shown, is made for a single predetermined code as indicated, with the proviso that the code is only correct and identical from the sensor the evaluation circuit is detected if, during the magnetic influence of the resistors 6 by the transmitter elements 9, there is no minus signal or no low signal on the H-rail and accordingly no high signal or positive signal on the L-rail. The individual functional sequences will be discussed further below - the resulting voltage states of the H-rail 25 and the L-rail 26 are evaluated by a switching transistor 17a connected to the H-rail, which operates directly on a bistable switching element 17 which has corresponding output switching states then takes over, releases locks or actuates safety circuits. A blocking transistor 27 is connected to the other potential rail (L-rail) which serves to decode the diode matrix 15 and forms the base of the H-rail against ground and can thus act directly on the switching state of the switching transistor 17a and further, preferably via a counter 18 actuates a safety circuit 20 in the form of a bistable element which, after a predetermined number of failed attempts, can likewise block the switching transistor 17a via a connecting line 28 and, at the same time, starts a timing element 22 via the same line, which, for example, switched as an oscillator, opens the counter must count up a predetermined counter reading before a new attempt is permitted.

The following mode of operation then results: The field plate resistors 6, which are preferably arranged in a surface matrix, are biased by the permanent magnet (not shown). By introducing a soft iron part selectively in the area of the field lines, where there are field plate resistors that penetrate them, there is a concentration in the area and an increase in the resistance of the corresponding semiconductor area by the concentration of the field line density.

The key matrix of the transmitter contains soft iron pins 9 distributed according to the selected code, congruent to the field plate dimension trix. If the key is brought into line with the field plate matrix, then the corresponding field plates are activated in the coded matrix fields, and a binary word with a number of bits corresponding to the number of fields is created. This binary word is compared with a code word preset by the corresponding connection of the outputs of the comparators 12 to the diode matrix 15 and a circuit is triggered if they match. As already mentioned above, the preset coding can also be carried out by appropriately connecting both the inverting and the non-inverting inputs of the comparators 12, that is to say in front of these.

The circuit of FIG. 5 can scan the internal coding of the key / transmitter and compare it with its stored information by placing the transmitter surface on the sensor surface and, appropriately, a corresponding engagement by an outer guide, thereby ensuring the alignment. Due to the bistable output switching element 17, which is preferably a bistable mechanical relay, which has a first changeover contact 17b and a second changeover contact 17c, the switching state remains mechanically stored, even in the event of a power failure.

If one considers the connection of the diode matrix 15 to the comparators 12 shown in FIG. 1, then it can be seen that in order for the switching transistor 17a to become conductive, the outputs of the operational amplifiers connected to the H-rail 25 must not go low, because in In this case, the transistor 17a would block and the bistable relay 17 could not be activated for release. In other words, a field plate resistor denoted by 6a must not control the comparator 12a connected downstream of it by increasing its resistance value and a positive voltage rise caused thereby, so that this operational amplifier switches through and places positive potential on the L-rail 26, since this would be one of the corresponding «correct» coding not influencing the resistance 6a. A positive potential on the rail 26 results in a leading control of the blocking transistor 27 via the diode 27a, which in this case puts the H-rail 25 at ground potential and therefore negatively biases the base of the switching transistor 17a to such an extent that it cannot switch through. The same naturally occurs whenever one of the outputs of the comparators 12 connected directly to the H-rail 25 via the assigned diode automatically sets this rail to low by a corresponding control by the assigned resistor 6.

The further sequence is such that when such an error signal occurs, for example on the L-rail 26, not only the transistor 27 is turned on, but also a counter input 18a of the counter 18 is applied via an inverter 29 and after a predetermined number of failed attempts (for example After seven failed attempts), the counter 18 sets a bistable element (flip-flop 21) with its outputs, which drives a further blocking transistor 30 via the connecting line 28, which then practically bridges the base and emitter of the switching transistor 17a and therefore ensures its blocking state, and on the other activates the timer 22 (oscillator), which must supply the counting input 18a of the counter 18 with a predetermined number of counting pulses before it can reset itself by a reset pulse at its reset input 19 and releases the sensor.

The bistable mechanical relay 17 arranged on the output side can be switched with its two coils in such a way that the two changeover contacts 17b and 17c are thrown into one position by one coil part and in the other position by the other coil part, in both positions over the Switch 17c a latch circuit is switched. With the other changeover contact 17b, any switching operations for unlocking and locking, alarming and the like can then be carried out. be made.

The control of the non-inverting inputs of the comparators 12 via capacitors 16 is essential for the present invention in order to counter problems that would otherwise arise in the field plate area in particular due to its high temperature response, the high component tolerances, general aging problems and all component drifts. Due to its size and its time constant in connection with the resistances involved (approx. 1 second), the capacitor merely conveys a corresponding voltage jump for switching over, but on the other hand effectively decouples the area of the comparators 12 from the field plate area, so that the tolerance problems mentioned do not occur which basically culminate in the fact that the desired output states and the stable rest positions of the comparators can practically hardly be predetermined by only voltage divider circuits.

In the present invention, the manner in which the encoder is effectively brought into the area of the sensor is also completely unproblematic - the long time constant results in a switching state when it is inserted, which can be evaluated for unlocking when the code is correctly identified.

In addition to the blocking of the sensor caused by the locking circuits in the area of the counter 18 with the oscillator 22 when a predetermined number of failed attempts is exceeded, the long time constant in the input area and the delayed reaction of the bistable switching relay 17 result in the practical impossibility of trying out, for example using a binary code generator to find the desired code. A calculation shows that, taking into account the delayed input reaction, the sensor is blocked for a predetermined period of time a predetermined number of failed attempts and the need to try at least 50% of the possible codes on a statistical average before a correct one is found, a period of around 24 years is required. This is based on only 20 field plate resistors 6, which results in a possible number of different code words of 220-1 combinations.

Claims (15)

1. A device on locks, for safety devices, locking mechanisms or the like, allowing for authorised access to rooms, buildings, automobiles and the like and/or for checking the authorised undertaking of activities and/or for arming and disarming alarm systems, comprising a transmitter (2) which acts as a key and a sensor (1) which acts as a lock part, the transmitter (2) comprising a predetermined distribution of magnetic or magnetically permeable material in the form of transmitter elements (9) which forms a code and which extends in at least one dimension, and the sensor (1) comprising, in the same spatial extension and association, a distribution of sensor elements for detecting the transmitter code, which sensor elements can be altered in their electrical function by magnetic influence, and data relating to the appropriate code, and an evaluation circuit also being connected after the sensor (1), which circuit, after a comparison of the transmitter code and the sensor code and upon determining identity effects release switching operations, characterised in that the sensor elements are field plate resistances (6), which can be altered in their ohmic resistance by magnetic influence and in that the voltage jumps of the field plate resistances (6) resulting from the selective resistance change under magnetic influence are simultaneously dynamically connected (in parallel) via capacitors (16) to associated inputs of comparators (12), which are connected after the field plate resistances (6).

2. A device according to claim 1, characterised in that both the districution of the transmitter elements in the transmitter (2) and the arrangement of the field plate resistances (6) in the sensor is formed as a surface matrix.

3. A device according to claim 1 or 2, characterised in that the magnetically controllable field plate resistances (6) are arranged in the manner of an integrated circuit with their associated connections on a carrier substrate (doped silicon chip) and in that a magnetic biasing device (permanent magnet) is provided, which produces a preferably homogeneous magnetic line distribution in the field plate resistances (6) in order to set a predetermined quiescent resistance value of said field plate resistances.

4. A device according to any one of claims 1 to 3, characterised in that the field plate resistances (6) of the sensor are connected via series resistances (10) to a constant supply voltage (+ U_B) and form with the series resistances a potentiometer and with the capacitors (16) an RC element.

5. A device according to claim 4, characterised in that a comparator (12; 12a, 12b, 12c) is associated with each field plate resistance (6; 6a, 6b, 6c) and in that both inputs of each comparator (12) are biased by a single bias potentiometer (13a, 13b, 13c), which is common to all comparators, in order to ensure a stable, defined output connection state.

6. A device according to claim 5, characterised in that the common bias potentiometer for all comparators (12) is formed by the series connection of a first resistance (13a), a medium offset resistance (13b) and a base resistance (13c), the two connection points of the offset resistance being connected via additional series resistances in each case with each of the two inputs (minus input or inverting input or plus input or non-inverting input) of each operation amplifier connected as a comparator (12).

7. A device according to any one of claims 1 to 6, characterised in that the code recognition is effected by the evaluation circuit at the outputs of the comparators (12) connected after each field plate resistance (6).

8. A device according to claim 7, characterised in that a rapid interrogating circuit (microprocessor, computer) is provided, which detects the output voltage configuration occurring during the dynamic control of the comparators (12) in series or in parallel and compares this with the predetermined codeword.

9. A device according to claim 7, characterised in that a diode matrix (15) is connected after the outputs of the operation amplifier connected as a comparator (12) for the purpose of codeword comparison.

10. A device according to claim 7, characterised in that the outputs of the comparators (12) connected after the field plate resistances (6) are connected to a common resistance network and the internal determining of the codeword in the sensor is effected by the corresponding selective connection of the outputs of the field plate resistances (6) to the respective inputs of the comparators (12).

11. A device according to claim 9, characterised in that the outputs of the diode matrix (15) are connected for the evaluation of the comparator outputs to two potential busbars (H-busbar 25; L-busbar 26) and in that a switching element (switching transistor 17a) is provided, which is controlled by one of the potential busbars and which activates a bistable output element, preferably a bistable switching relay (17) in the event of an appropriate codeword recognition.

12. A device according to claim 11, characterised in that in the event of a wrong transmitter code, one or both output potential busbars of the diode matrix (15) conducts an electric potential, which either blocks the switching transistor (17a) for activating the bistable relay (17) directly or effects this action via an additional blocking transistor (27), which applies a blocking potential to the potential busbar activating the switching transistor.

13. A device according to any one of claims 1 to 12, characterised in that a safety circuit is provided to prevent repeated unsuccessful attempts, comprising a counter (18), which is activated upon each unsuccessful attempt and a bistable member (21), which is arranged after the counter (18), which directly blocks the switching transistor (17) and which blocks the counter against further attempts by starting an oscillator (22).

14. A device according to any one of claims 1 to 13, characterised in that the active surface matrix plate area of the transmitter (2) is part of a ring worn by the user.

15. A device according to claim 2, characterised in that the surface matrix of the transmitter elements in the transmitter (2) is formed by soft iron pins (9).

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