GB2239673A

GB2239673A - Electronic lock with inductive transmission

Info

Publication number: GB2239673A
Application number: GB9027040A
Authority: GB
Inventors: Peter Hausmann
Original assignee: Bauer Kaba AG
Current assignee: Bauer Kaba AG
Priority date: 1989-12-15
Filing date: 1990-12-13
Publication date: 1991-07-10
Also published as: FI906136A; JPH03191186A; FR2656028A1; CH680082A5; CA2030266A1; IT1244026B; FI906136A0; NO905342D0; ES2027861A6; AU6597290A; NO905342L; SE9003996L; IT9022179A0; DE4036575A1; SE9003996D0; GB9027040D0; NL9002730A; IT9022179A1

Abstract

The invention relates to a lock cylinder with an associated key which, apart from its mechanical locking function, also allows the inductive transmission of an electric signal between the key and the lock cylinder, which can e.g. be used for the electronic identification of the key. The signal transmission is brought about by a coil (21) in the key and a coil (16) in the lock cylinder, which are arranged in such a way that their cores (22, 14 respectively), together with corresponding legs (15.1, 15.2) form a common, closed core for both coils in two positions of the rotary lock cylinder (12) differing by 180 DEG . The reading legs (15.1, 15.2) are so arranged in the bore for the lock cylinder (12), that the core (22) of the key coil (21) slides between them during key insertion and is positioned between them when the key is completely inserted. This not only permits a signal transmission when the key is completely inserted, but also during its insertion process. The arrangement is such that the sum of the air gaps I1 + I2 between the two cores remains constant when the key is rotated. <IMAGE>

Description

LXK CYLINDER 1CM SIGNU TRANSMISSION BEMLN THE KEY AND CYLINDC k The

invention is in the f ield of locking devices and relates to a lock cylinder with a key according to the preamble of claiin 1, in which an electric signal can be transmitted between the key and the lock cyLinder.

In an age with ever increasing needs for security and ccntrol, a key is no longer an adequate identification for authorization to enter a secure area. Thus, access cannot be time-limited, if the key is the sole accessallowing means. In order to obviate this problem, attempts have already been made in different ways to link with the physical lcek cylinder and key, an electronic locking with corresponding electronic identification of the access-requester.

The problem of the present invention is to obtain such a link and where, despite the additional electronic identification, on the part of the accessrequester only a key is required as the physical access means and the only access-creating action involves turning the key in the lock cylinder. Thus, in other words, electronic signals are transmitted from the key to the lock cylinder. Transmission must be possible in two clearly defined lock cylinder positions (lock unlocked and lock locked). Transmission is to take place during the insertion of the key into the lock cylinder, so that the electronic answer to the signals, e.g. a release of the mechanical locking system, already exists when the key has been ccxTletely inserted. The transmission must be able to transmit low current or voltage value signals and must also function in a ocrnpletely satisfactory manner if a force canponent at right angles to the insertion direction acts on the key during insertion.

This problem is solved by a key and a lock cylinder which, according to the characterizing part of claim 1, are provided with weans allowing an inductive transmission of an electric signal between the key and the lock cylinder. The inventive locking mechanism is explained by means of the following drawings, wherein show:

Fig - 1 A key and a lock cylinder with the inventive inductive transmission.

Fig. 2 A diagram of the inventive transmission.

Fig. 3 A variant of the inventive loc3cing mans with an armiate lock cylinder coil core.

ed rig. 1 shows h::w the inductive transmission mans are integret into the lock cylinder 1 and the key 2. The lock cylinder 1 coTprises a stationary part 11 and a lock cylinder 12 rotating in a correspc>iding round cpening of said stationary part 11. That part of the lock cylinder 12 which faces the insertion opening for the key, is subdivided by a through radial slot 13 into two portions. Through said slot 13 the key is inserted in the lock cylinder 1. In the lock cylinder 1 a transnission yoke 14 is positioned in such a way that it so embraces the part of the lock cylinder 12 provided with the slot 13, that two parallel reading legs 15. 1 and 15.2 face one another on the legs 14.1 and 14.2 of the transnission yoke 14 and are positioned on the inner ci=-nference of the opening rrade in the stationary part 11 of the lock cylinder 1 for the lock cylinder 12 and extend into the vicinity of the key:Insertion opening. A lock cylinder coil 16 (primary coil) is wa,.md onto the central portion 14.3 of the transmission yoke 14, which consequantly foms the core of the lock cylinder coil 16. For c,7aluatLng the induced signal, the lock cylinder coil 16 is interconnected with a suitable electronics read out device (not shown).

The key 2 contains a key coil 21 (secondary coil) with a core 22, which is positioned at right angles to the insertion direction A of the key 2 in the lock cylinder 1. The coil 21 is so positioned in the key 2 that, if the key 2 is inserted as far as possible into the lock cylinder 1, it is 1 c>--a44.-ed in the vicinity of the aids of the reading legs 13.1 cmd 15.2 rr--.cte fiui the insertion opening. Ihe key 2 also contains means (signal generator) eiabling an electric signal to be supplied to the key coil 21, although this is not expressly sh--h%m in the drerwing.

The lock cylinder 12 has two clearly defined positions (lock unlocked and lock locked), which differ from one another by half a turn. The lodx is designed in such a way that in both defined positions of the lock cylinder 12, the key 2 is so inserted in the stationary lock cylinder part 11, that the key coil 21 is positioned between the reading legs 15.1 and 15.2. in 1 i 0 both these positions the distance bet-ween the ends of the core 22 of the - 11 that the re key coil 21 and the reading legs 15.1 and 15.2 is so sma CO 22 of the key coil 21, together with the reading legs 15.1 and 15.2 and the transnissio,1 yoke 14 beccmes the closed. cwmm core for both the coils 16 and 21. An electric signal applied to the key coil 21 then produces a magnetic field in the ccmnm core and consequently induces a corresponding signal in the lock cylinder coil 16.

When the key 2 is inserted in the lock cylinder 1, the key coil 21 slides along the reading legs 15.1 and 15.2. Both d=ing this insertion time and whenever the key is ccnipletely inserted, a signal transmission is possible.

It is also conceivable to intexchange the functions of the primary key coil 21 and the secondary lock cylinder coil 16, so that the electronics of the lock cylinder, via the lock cylinder coil can influence the key signal generator.

The diagram-r--tic f ig. 2 serves to explain the quantities of the inventive arrangeTcit an which is dependent the intensity of the signal induced in the lock cylinder coil 16 and, as a consecraence thereof, the cptirrun design for the inductive trans-nissian mans.

The transmission quality is mainly dependent cx-1 the diameter and number of turns of the two coils 16 and 21, but these are virtually predetermined by the fact that it is necessary to hc>jse the coils in a lock cylinder and a key, whose size should not vary f=m conventional CO- IS.'LrICtiO-15. In addition, the degree of coupling is dependent on the core material, whose r,-agnetic permeability should be- as high as possible.

The degree of coupling is also dependent on the length of the ccr-irTo.7. i core of the two coils 16 and 21, which is formed from the transnission yoke 14, the reading legs 15.1 and 15.2 and the core 22 of the key coil 21. This length is, according to fig. 2, the scun of the distances a and b. The intensity of the signal induced in the lock cylinder coil 16 is approxirrately inversely proportional to the length of the ccxmK>n core. i.e. is at a maxirrum when the caTmon core is at its shortest. However, this means that the intensity of the induced signal is dependent an the actual insertion depth of the key. The highest intensity of the induced signal is reached when the core of the key coil is located at that point between the reading legs 15. 1 and 15. 2 frcm which there is a min distance to the legs 14.1 and 14.2 of the transmission yoke 14. However, in order to be able to fully utilize the advantage of the inventive arrangement, which permits the reading in of the key signal during key insertion, the reading electronics in the lock cylinder mast be designed in such a way that they are able to recognize as such the higher length of the cam= core in the position in which the key coil 21 first cc:mes to rest between the reading legs 15. 1 and 15.2.

It can also be proved that the intensity of the induced signal is sensitively dependent cin the sun 1 1 + 1 2 of the two distances between the core 22 of the key coil 21 and the reading legs 15.1 and 15.2, but not on their relative quantities 1 1 or 1 2 When the key is inserted the two air gaps 1 1 and 1 2 act in inversely proportional niwmer. Thus, if one increases, the other decreases by the sane aTKxmt, so that the air gap is always equally large, even if the key is moved between the reading legs in the direction of the key coil axis. Thus, the magnetic resistance of the arrangement rernains approx:bnately the same, i.e. it is constant.

The sum 1 1 + 1 2 can be minimized by a corresponding precise manufacture of the lock cylinder and key. If the key and the lock cylinder are rranufactured according to the standard rules of the art, the key clearance in the lock cylinder is such that a key signal of an acceptable energy level can induce a lock cylinder signal, which can be read without difficulty by an acceptable reception electronics.

The relative quantities 1 1 or 1 2 are dependent on the position of the key 2 between the reading legs 15.1 and 15.2, which is in turn dependent on which forces directed radially to the lock cylinder axis act on the key during insertion. In other words, the transmitted signal is not dependent on how the key is inserted in the lock cylinder, which is very advantageous, because it would be very difficult to influence the sane by corresponding 0 1 1 4 means on the lock cylinder or an the key.

Fig. 3 shows another variant of the inventive locking mechanisn, in which the core 14 of the lock cylinder coil 15 is arcuate, as cpposed to the angular construction in the other drawings. This nakes it possible to limit the core length to a minimum.

Claims

Claims

A locking mechism comprising a lock cylinder and associated key, incorporating transmission means operable to transmit an electric signal between the key and the lock cylinder by inductive transmission wherein the sum of the air gaps in a magnetic circuit between the key and the lock cylinder with the key inserted remain substantially constant when the key is manipulated.
2. A locking mechanism according to claim 1, characterised in that a coil (21) with a core (22) is located in the key, that in the lock cylinder there is arranged a coil (16) with a core (14.3), and that the shape and reciprocal position of the two cores is such that in two clearly defined positions of the rotary lock cylinder (12) they form a closed core common to both coils.
3. A locking mechanism according to claim 2, characterised in that the key coil 21 is a secondary coil and is interconnected with a signal generator, whilst the lock cylinder (16) is designed as a primary coil and is interconnected with a corresponding electronics read out device.
4. A locking mechanism according to claim 2, characterised in that the lock cylinder coil (16) and the 1 key coil (21) are connected in such a way that they can serve both as primary coils and as secondary coils.
5. A locking mechanism according to any one of the claims 2 to 4, characterised in that at both ends of the core (14) of the lock cylinder coil (16) are fixed two reading legs (15.1. 15.2), that during the insertion of the key the core (22) of the key coil (21) slides between said legs and, when the key is completely inserted, is positioned between them.
6. A locking mechanism according to any one of the claims 2 to 5, characterised in that the core (14) of th lock cylinder coil (16) so surrounds the rotary lock cylinder (12), that the reading legs (15.1, 15. 2) are positioned facing one another on the internal diameter of the bore in the stationary lock cylinder part (11), in which the lock cylinder (12) turns and forms part of the surface of said bore.
7. A locking mechanism according to claim 6, characterised in that the core (14) of the lock cylinder coil (16) is arcuate or is shaped like three legs joined together at an angle.
8. A key for a locking mechanism of any one of the preceding claims, characterised in that the magnetic k 1 circuit has a part (21,22) enabling information and/or energy to be transmitted between the lock cylinder and the key.
9. A key according to claim 8, chaiacterised in that the part of the magnetic circuit has a coil (21).
10. A key according to claim 9, characterised in that the part of the magnetic circuit has a coil (21) with a core of ferromagnetic material (22) in the coil interior, the core extending from one narrow side of the key shank to the other.
11. A locking mechanism substantially as herein described and shown in the accompanying drawings
12. A key substantially as herein described and shown in the accompanying drawings.

Published 1991 at The Patent Office. State House. 66/71 HighHolborn. LondonWC I R47P. Further copies may be obtained from Sales Branch, Unit 6. Nine Mile Point. Cwmfelinfach. Cross Keys, Newport. NPI 7HZ. Printed by Multiplex techniques ltd, St Mary Cray, Kent.