GB2047326A - Locking device for preventing unauthorized access - Google Patents

Abstract

A locking device comprises a key 9 and a lock 11 having a key-receiving opening 10. The key 9 is provided with a code track made up of a number of magnetic wire lengths 7a, 7b,... and 8a, 8b... which can be switched into different magnetic field states in accordance with the Wiegand effect by external magnets 12, 13 disposed along the key- receiving opening 10. At least one sensor coil 14 is located near one of the magnets 13, and a pulse of needle-like shape is induced in the sensor coil by the switching of the magnetic wire lengths into a different field state as they pass magnet 13; this pulse is then used to condition the lock 11 to permit authorized access upon insertion of the key 9. <IMAGE>

Description

SPECIFICATION Locking device for preventing unauthorised access This invention relates to locking devices for rooms, buildings, objects and particularly cars, which are to be protected and are secured by doors, so as to safeguard them against unauthorised access or actions, including the removal of the object or car. Conventional cylinder locks have been used for this purpose. By appropriately varying the tumbler configuration these may provide up to 5000 lock combinations, so that it might seem that unauthorised actions are impossible. However, in practice the opposite is proved every day, even when alarm systems are also provided. Such alarm systems are available in numerous embodiments, separate from the lockkey area, for the additional-protection of installations, objects and particularly cars.They include, for example, alarm systems based on the principle of disturbing an ultrasonic field.

Even in the case of very complicated known locking systems it has proved possible to obtain unauthorised access by duplicating the key. Owing to the nature of locks such as conventional cylinder locks where the information code of the mechanical tumblers is the sole means by which the lock can be opened and this information code must be mechanically available in every lock, it is possible, for example by inserting a deformable element, to detect the tumblers of a cylinder lock and then, on the basis of this information, immediately qr subsequently obtain a corresponding duplicate key. It is then possible to take possession of the object or the car, apparently legally, or enter locked rooms without difficulty.

Our copending U.K. patent application No.

45387/78 deals with this problem, and parts of the specific description of this copending application are also relevant to the present application. Application No. 45387/78 describes an apparatus for actuating a security device to prevent unauthorised access to rooms, buildings, cars etc. and/or possibly simultaneous enabling and disabling of alarm systems, with an actuator element or key permitting authorised action, and a counter element or lock responding to the latter, the actuator element comprising at least one nonmechanical code track and a sensor being disposed in the counter element, which sensor scans the code track by a non-physical action and delivers a corresponding output signal to a logical switching circuit comprising a memory (PROM) so as to carry out a comparison and deliver a control command.In the case of this apparatus, the only appropriate lock combination which permits opening is not present in the mechanical, physical sense, nor is it usually stored in the direct vicinity of the lock, so that in practice unauthorised actions, without the use of force, are excluded.

Furthermore, the apparatus allows a number of possible lock combinations which is greater by several magnitudes than that conventionally attainable, so that an empirical determination of the correct combination is impossible.

The copending application further describes an optoelectrical device on locks, which relates particularly to the logical evaluation of data information in actuator elements or keys and to the logical circuits used for this purpose. Actual codings are detected and evaluated in any coded form, for example, binary coded, signal pulse sequences, stored on two or more parallel tracks.

Evaluation preferably takes place via optoelectrical systems, based on infra-red light radiation by means of suitable light-emitting diodes, transirradiation or irradiation of the material having the codings and detection of the brightdark field disposition by means of suitable sensors.

The use of light rays in these proposed optoelectrical devices and evaluation circuits, even if in the invisible infra-red range, could prove to be too complicated for evaluation, because soiling effects, slight signal amplitude deviations or noise and a correspondingly complicated and high quality discrimination together with a certain dependency on the relative movement between information carrier and sensor require suitable compensation measures and high quality evaluation logics, which are not always simple.

To meet this possible further problem, means are required which reduce the expense in the sensing and evaluation field and which render sensing foolproof with a view to obtaining more freedom from the previous complete dependency on the relative movement between actuator element and sensor.

The present invention provides a locking device comprising an actuator element or key on which there is at least one code track, and a counter element or lock which senses the coded information of the actuator element by a nonphysical action, the code track being formed from a specified distribution of magnetic flux lines on the actuator element and a sensor comprising at least one electric coil being provided in the region of the counter element so that successive voltage pulses may be induced in the electric coil by the magnetic flux line distribution, which pulses are coordinated with an insertion or separating movement between the actuator element and the counter element.

Preferably, magnetic elements or wire lengths are provided on the actuator element to produce the magnetic flux line distribution, each of the wire lengths having a high retentivity shell region and a low retentivity core, such that they can be switched into two different magnetic field states by the effect of external magnetic fields in accordance with the Wiegand Effect.

The locking device has the advantage that, while retaining the sensing of the coded signal information by a non-physical action, interference effects attributable, for example, to soiling etc., no longer occur. Furthermore, the locking device of the present invention does not require any kind of external supply sources in the sensing area, i.e.

where the signal information is produced, since the coded information is formed as an electrical signal from the movement between information carrier and sensor. In an advantageous embodiment of the invention, it is completely independent of the actual speed of movement.

The extraordinary size of the constant signal amplitude of the coded information which is obtained in the preferred embodiment and occurs at practically every speed is also of particular advantage, as any pulse shapers or discriminating measures are thus rendered superfluous in the further evaluation circuit.

By means of a suitable formation in the sensing region of the counter element it is possible to provide the particularly advantageous feature that return movements, and therefore movement against the actual direction in which the actuator element or key is inserted in the counter element or lock, do not lead to the production of unnecessary signal information so that logical discriminator circuits, which separate such undesired signal information, are also unnecessary.

An embodiment of the invention is shown in the accompanying drawing, in which: Figure 1 shows a side view of a receiving opening in the sensor region of the counter element, in which a key or actuator element, shown schematically, is inserted; this inserted key is shown in plan view in Figure 1 for a better understanding, Figure 1 a shows the possible arrangement of sensing coils and exciting or actuating magnets in the sensor region, when several coded tracks are used on the actuator element, Figure 2a to 2c show the change of mangetic field state of a magnetic wire, acting as carrier of signal information, it being possible to form a code track on the actuator element by a plurality of such small magnetic wires, and Figure 3 is a graph showing the field shape of the external actuating magnetic field which causes the switching or magnetic field inversion at the small signal-producing magnetic wires and the electric pulses in the sensor coils produced by the inversion of the magnetic fiejd.

The arrangement of magnets and small magnetic wires shown in the Figures is such as to obtain the effect of magnetic field state change in the magnetic wires by the action of external magnetic fields in accordance with the Wiegand Effect, shortly to be described.

The basic concept of the invention lies in producing a non-physical interaction between the sensor scanning the coded signal information in the actuator element and the regions on the actuator element producing this signal information by means of a magnetic interaction instead of the optoelectrical effect described in our copending patent application No. 45387/78.

Such a magnetic interaction renders unnecessary some of the circuit elements and logical circuit sequences mentioned in our copending patent application; however, it should be pointed out that the fundamental features of evaluation electronics described in the copending application can also be used for the present invention.

In the simplest case the actuator elements, which in the following will simply be called a key element and may assume various forms, incorporates permanent magnets or other discreet material particles, which produce a permanent magnetic field and which, on passing one or several sensor coils, induces in the latter corresponding voltage jumps.

However the present invention relates, in a particularly advantageous embodiment, to the utlization of the so-called "Wiegand Effect", which is known per se, and which will therefore only be briefly described. This Wiegand Effect is based on the fact that specially treated and hardened magnetic wires of a homogeneous alloy can possess a hard shell and a soft core in the magnetic sense, i.e. a certain outer wire region is highly retentive and an inner wire region has a low retentivity. As a result, a comparatively small external magnetic field may be used to produce magnetic inversion of the inner wire region while a much greater external field is needed to vary the magnetization direction of the shell part.

Figures 2a to 2c show what is meant; in Figure 2a the "Wiegand" magnetic wire - of course other geometrical forms of "Wiegand" magnetic elements are also conceivable -- is magnetically saturated, i.e. both the shell region 2a and the core 2b of the magnetic element or magnetic wire 2, as it will simply be called in the following, are magnetised in the same direction. This is indicated by the thick arrows 3 for the shell region and the thin arrows 4 for the core region, these arrows extending the same direction. The result is a comparatively large outer magnetic field 5, which distinctly exceeds the geometric dimensions of the magnetic wire 2.

A comparatively small magnetic field is now applied in the opposite direction to a magnetic wire 2 which is thus saturated - if, for example, the magnetic field effect in the representation of Figure 2a extends in the positive direction, the magnetic field for the reversal shown in Figure 2b is negative -- and the low retentivity core of the magnetic wire 2 is magnetised inversely with respect to the preferred magnetic direction of the shell material, as shown by the arrows 4' for the core region which now extend in the opposite direction. As a result, the outward magnetic field of the magnetic wire 2 of Figure 2b is practically nil; there is no obvious magnetic field, apart from the ends, extending beyond the dimensions of the magnetic wire 2. By applying a positive outer magnetic field, the magnetic wire 2 according to Figure 2c can now switch back from the magnetic field state of Figure 2b to the original state of Figure 2a, i.e. in Figure 2c the arrows which indicate the orientation of the core magnetic field again extend in the original direction as shown in Figure 2a. The transition from Figure 2b to Figure 2c is an extremely rapid inversion of the magnetic field to create the outer magnetic field 5' and it is preferably this quick inversion process, precipitating a very strong mangetic field, which is used to produce a signal.If a positive magnetic field, together with an electric sensor coil, are brought at the same time and place into the range of a mangetic wire 2 which is in the state shown in Figure 2b, the inversion of the magnetic field from Figure 2b to Figure 2c will produce an electric pulse in the coil which may have a surprising strength and, according to the type of coil, may range from 0.5 to 12 volts.

With regard to possible noise in the system, the pulse, which is only produced a single time with a clear and distinct conciseness when the magnetic field is inverted, has a very high signal-to-noise ratio, and this pulse can be produced in any combination of direction and polarity. A particularly important factor is that no external supply potential is required to produce the pulse, since merely the action of bringing the magnetic wire 2, in the state shown in Figure 2b, within the range of a positive magnetic field causes inversion of the magnetic field and pulse induction.

The field shape of the external magnetic field is shown as curve I in Figure 3 and the respective pulses which are produced in the sensor coil are shown as II. It can be seen that, when the magnetic field I rises in the positive direction to a certain strength, approximately at the moment tg, a sharp needle pulse II occurs, resulting from reversal of the magnetic field formed by the magnetic wire from the state of Figure 2b to the state of Figure 2c. The peak field strength of the external magnetic field may lie between 100 and 1 50 oersted; the negative external field strength sufficing to switch the magnetic field of the magnetic wire 2 back to the state of Figure 2b is in this case approximately 20 oersted.

It is particularly important that, as shown in Figure 1, by embedding magnetic wire lengths 7a, 7b, 7c ..... 7i having the "Wiegand Effect" or, when further code tracks are provided, magnetic wire lengths 81, 8b, 8c 8i in a key element, any coding of YES-NO FIELDS can be obtained for each code track of the key element.

The type of codings can be such as explicity described in our aforementioned copending patent application. If such a key element 9 with code tracks 7, 8 i i is inserted in the receiving opening 10 of a counter element 1 , the magnetic orientation of the individual small magnetic wire portions 7a, 7b 8a, .... 8b .... is initially insignificant, for a first external magnet 12 changes all the magnetic wire portions 7a, 7b ..... 8a, 8b .... .. to a specified magnetic field state due to the effect of this actuating magnet 12, i.e. preferably to the state of Figure 2b. If several of the magnetic wires enter the receiving opening 10 in the state shown in Figure 2b, they are ineffective and remain in this state in this area of the counter element 11.At least one scanning or sensor coil 14 for at least one code track disposed on the key element 9 is provided in the region of a second external actuating magnet 1 3.

The second actuating magnet 13 then produces a magnetic field such that the magnetic wire 2 changes from the state shown in Figure 2b to that of Figure 2c according to the "Wiegand Effect".

This sudden increase of the magnetic field induces in the coil 14 L & the above-mentioned needle pulse 11, which is very concise and has an extremely high signal-to-noise ratio.

It can be seen that the induction of such a needle pulse II is totally independent of the speed of insertion, for the change from the magnetic field state shown in Figure 2b to that shown in Figure 2c takes place in the presence of a certain external magnetic field, not as a function of speed.

Therefore, if one of the magnetic field lengths or wires 7a, 7b ...... 8a, 8b , for example the magnetic field lengths 7c, approaches the actuating magnet 13, nothing happens as long as the external magnetic field strength at which the "Wiegand wire" turns over to a different field state is not reached. This magnetic field strength is reached at the point when the magnetic wire 7c slides past the actuating magnet 13, and any potential relative speed is possible, from almost nil up to an extremely high speed. At this moment the magnetic field state of the respective magnetic wire length embedded in the key element 9 changes abruptly.The speed of this change is obviously also independent of the speed of insertion, and therefore the magnitude of the electric pulse which is produced in the coil 14 is independent of such factors and is solely a function (,f the dimension of the respective magnetic wire in the key element 9 and of the number of turns of the sensor coil, which can be of any number given an appropriately thin wire cross section.

It can be seen that even a partial withdrawal of the key element 9 with the embedded small wires 7a, 7b ..... 8a, 8b is unimportant, for withdrawal past the actuating magnet 13 no longer causes an individual magnetic field variation of the small magnetic wires unless they are withdrawn as far as the first external actuating or conditioning magnet 12 when a new reading is called for. The production of the electric needle pulses, which are induced in at least one coil 14 and are to be associated with individual codings, is therefore completely independent of the respective speed, of vibratory motions, of retracting motions etc., and the read out can take place in a clear and distinct manner.

Evaluation of the electric pulses thus produced in the sensor coils 14 can take place in any fashion, but preferably by means of the logical circuits described in our copending patent application No. 45387/78. In this respect it is also particularly important that the actual evaluation circuits are preferably not in the region of the lock, not even in the region of the door, but may be disposed in practically any remote location, even in the cellar etc. of a house, and therefore out of reach of strangers, because the pulses which are produced have such strong amplitudes that they can reliably be discriminated and evaluated at any time, even via long connection lines.

A number of modifications are possible when using the Wiegand Effect; thus, the magnetic field strengths produced by the conditioning magnet 12 and the actuating magnet 13 can be the same, whereby pulses which can be evaluated are produced in the read-out element each time that the magnetic wire lengths, which are thus affected, are reversed. In fact, a pulse which may be evaluated is also produced when the magnetic wire 2 changes from state 2a to, e.g. state 2b, this pulse extending in the negative direction in Figure 3 and being indicated by Ill.

Since the number of codings is considerably increased by each additional code track on the key element 9, any number of code tracks can be disposed on the key element as required. Sensing can then take place as shown in Figure 1 a, a conditioning magnet 12' and an actuating magnet 13' are provided, and are effective for all the sensor coils 1 4a, 1 4b, 1 4c, 1 4d which are disposed in the vicinity of the actuating magnet 13'.

The pulses which are induced in the sensor coils 14, 1 4a, 1 4b are practically independent of temperature and have a constant high quality so that multiple evaluations of a phenomenon occurring as a result of an encounter between information carrier and sensor are impossible, for the magnetic field of a small magnetic portion 7a, 7b 8a, 8b can only vary once under the effect of an actuating magnet of a given polarity.

It is of course possible to incorporate a certain mechanical design for the key element, e.g. to provide it with a specially formed bit, so as to open doors, locks etc. in a mechanical manner. In this case, however, the electric sensing of the code track region initially permits this opening procedure and/or releases additional key-bolts and locking mechanisms and/or disables or, in the case of an incorrect key element, enables and triggers additional alarm systems.

In order not to interfere with the magnetic field states of the small magnetic wires which are embedded in the key material, it is advisable to form the key element of a non-magnetic material, e.g. a suitable plastics material.

Claims (8)

1. A locking device comprising an actuator element or key on which there is at least one code track, and a counter element or lock which senses the coded information of the actuator element by a nonphysical action, the code track being formed from a specified distribution of magnetic flux lines on the actuator element and a sensor comprising at least one electric coil being provided in the region of the counter element so that successive voltage pulses may be induced in the electric coil by the magnetic flux line distribution, which pulses are coordinated with an insertion or separating movement between the actuator element and the counter element.

2. A locking device according to claim 1, wherein magnetic elements or wire lengths on the actuator element are provided to produce the magnetic flux line distribution, each of the wire lengths having a high retentivity shell region and a low retentivity core, such that they can be switched into two different magnetic field states by the effect of external magnetic fields in accordance with the Wiegand Effect.

3. A locking device according to claim 2, wherein a first conditioning magnet is provided in the region of an insertion opening of the counter element or lock receiving the key or actuator element, which conditioning magnet is adapted to move all the magnetic wire lengths into a specified magnetic state, these wire lengths being disposed in or on the key and jointly forming at least one code track, a further actuating magnet being provided for switching all the magnetic wire lengths back into an initial magnetic state.

4. A locking device according to claim 3, wherein at least one sensor coil is disposed adjacent to at least one of the conditioning and actuating magnets, a respective needle pulse being induced in this sensor coil by the magnetic change of state of the magnetic wire lengths disposed in the key.

5. A locking device according to any one of claims 2 to 4, wherein the magnetic wire lengths are embedded in the key and covered with at least one surface layer, such that their distribution cannot be discerned.

6. A locking device according to any one of the preceding claims, wherein the actuator element or key comprises a longitudinal portion with a mechanical bit formation for additional mechanical release and unlocking of the lock.

7. A locking device according to any one of the preceding claims, wherein the material of the key is non-magnetic.

8. A locking device substantially as hereinbefore described with reference to and as shown in the accompanying drawing.