GB2085064A - An Electronic Lock and Key Therefor - Google Patents

Abstract

An electronic lock, particularly for showcases and the like, opened by a key with a combination of conductive (a, c, e, g, h) and non-conductive (b, d, f) elements which in and only in a corresponding lock allows derivation of an opening signal. <IMAGE>

Description

SPECIFICATION An Electronic Lock and a Key Therefor This invention relates to electronic locks and keys therefor particularly, but not exclusively, for sale room cabinets or showcases.

A sale room in which extremely valuable articles or wares are displayed in many showcases, where the public are present in large numbers and where the cases are continually opened and closed by salesmen removing and replacing articles in order to allow closer inspection by prospective buyers, poses certain unique security problems concerned mainly with the prevention of opportunist theft and with the maintenance of locks.

Due to heavy day-long use, keys become damaged or bent and replacement can involve accumulated errors, especially where the originai key is not available. Loss of a key can involve replacement of the lock which can be expensive and time consuming whilst, unless a similar process is followed, any particular showcase has, for all time, one particular key. Experience has shown that expert thieves have managed to gain access to these cases, unnoticed during the often vigorous activity in the sale room.

The invention provides a lock and key combination comprising a key having a plurality of electrically conductive and electrically nonconductive elements arranged in a predetermined pattern, and a lock including means for producing a signal from each of said elements, the state of the signal being dependent upon whether said element is electrically conductive or electrically non-conductive, transformation means for effecting a predetermined transformation of the states of said signals to produce a plurality of further signals, detecting means for producing a given output signal at a given state of said further signals most suitably when and only when said further signals have the same predetermined state as each other, and locking means arranged to be operated by said output signal.

In the drawings herein, for example, as fully detailed later, there is a key (Fig. 1) showing the pattern of elements a to h in which b, d and fare non-conductive, and a lock (Fig. 3) with signal providing means (6), transformation means (8, G3) detecting means (G,) and locking means (G2, Tr, Ry).

The invention may alternatiyely be stated as providing an electronic lock and key that comprises a key having a plurality of conductive elements arranged in a predetermined conducting pattern and a lock having a signal generator producing a parallel set of signals, a release unit that produces a signal for release of a bolt or other detent only on receipt of a certain unlocking, parallel arrangement of signals, a setting unit having a plurality of conductive elements the conducting arrangement of which is settable in a pattern complementary to that of the key, and means to convey in parallel the set of signals from the generator to the release mechanism via the key and setting unit whereby the arrangement of the signals determined by the pattern of the one is converted into the unlocking arrangement by the pattern of the other.

Such a lock can be designed to have the following advantages, of particular utility in the aforementioned conditions: (a) it is simple, there is no unlocking code or combination that has to be remembered by a salesman; (b) the coding of a key cannot be ascertained visually or by a momentary inspection and, for example, a quick wax impression of the key is useless; (c) should a particular key be lost or if there is a suspicion that an unauthorised person may have been able to make a detailed examination of the key, it is a quick and simple operation to recode the lock to render the particular key unusable; (d) the quick recoding of the lock enables the key required to open any particular lock to be changed as often as required, for example hourly or at random short intervals;; (e) the locks are failsafe, that is a failed or switched off power supply renders the lock inoperable; (f) an aural or visual aiarm can be connected to the lock to be triggered if the case is not relocked within a given period after opening; (g) a delay can be built in between insertion of a key into the lock and the lock's response, to confuse possible attempts at code breaking; (h) the power supply can be adapted to run from the mains, an external battery or an internal battery; and (i) by use of setting units with the same pattern, particular locks can be grouped to be opened by the same key.

In a preferred embodiment the key has the plurality of electrically conductive elements on a surface thereof and insulated one from the other, with each element insulated from or electrically connected to a common conductor for the key, a particular key having a selection only of the elements connected to the common conductor, to accord with the predetermined pattern. A socket is provided to receive the key and make separate electrical contact with each of the elements and the common conductor and has a series of outputs each corresponding with a respective one of the key element contacts or with the common conductor contact. The release unit includes an electronic logic circuit the elements of which are connected to have a number of inputs and an output from which the release signal issues.The setting unit is changeable and is connected between the outputs of the key socket and the inputs to the logic circuit.

Particularly, the logic circuit is a binary circuit having means to hold all the inputs to one logic level, corresponding to the locked condition, and the common conductor output from the key socket is connected to the other logic level whereby, on insertion of a key in the socket, the logic circuit inputs connected via the setting means to a key element itself connected to the common conductor are driven to said other logic level.

More particularly, the logic circuit has a pair of inputs, of which one is inverting, corresponding to each key element and the internal connections of the setting unit additionally enable all the key element socket contacts to be at the same logic level.

Conveniently, the key is cylindrical with a series of electrically conducting ring elements.

The key may be in the shape of a ball point pen with the elements in the barrel. The changeable setting unit may be a plug-in printed circuit board or another "key". In either event, the setting unit is, of course, only accessible when the lock is open.

The invention is illustrated, by way of example, in the drawings, wherein: Fig. 1 is an elevation of a key in accordance with the invention; Fig. 2 is an enlarged, longitudinal part-section of the key of Fig. 1; Fig. 3 is a circuit diagram of an electronic lock in accordance with the invention; and Fig. 4 is an enlarged, longitudinal part-section of one form of changeable setting unit.

As shown by Figs. 1 and 2, the key 1 is conveniently in the shape of a pen and has in its barrel a series of, in this example eight, metal, electrically conducting ring elements a to h, each separated by an insulating washer 2 from the other and from the rest of the metal body 3 of the key. The key also has a central conducting core 4 in electrical connection with the body 3 and with those ring elements a to h not insulated therefrom by an insulating bush 5 (see Fig. 2). In the example shown, ring elements b, dand fare insulated from the core 4 and elements a, c, e, g and h are electrically connected to the core 4 and hence to the key body 3.

Visually, it is not possible to determine whether or not any particular ring element is electrically connected to the key body. Clearly, with eight ring elements, there are 254 effective combinations (leaving aside for reasons apparent later the combinations of all elements connected or all insulated).

A circuit diagram of an electronic lock is shown by Fig. 3 to consist of a socket 6 to receive a key 1 and having a separate contact to register with and electrically connected to each key element a to.

h; an additional contact 7 being provided to connect the key body 3 to the Lo (0 volt) line for the circuit.

The contacts of the socket 6 each have an output line a, b, c, d, e, f, g orh leading to a connector for a setting unit in the form of a plugin card 8.

The logic circuit 9 of the lock is designed around an eight input NAND gate G, whose output (pin 8) is driven Lo when all the inputs (pins 1, 2, 3, 4, 5, 6, 11 and 12) are Hi. When this condition obtains the Lo output is passed to an output circuit 10 where it is input at (pin 13) to a two input NAND Gate G2, the other input (pin 12) of which is held Hi by a pull-up resistor R so that a Hi output signal (at pin 11) is applied to the base of an NPN driver transistor Tr to turn the transistor "ON" and thereby energise a relay Ry connected to the collector of transistor Tr. The relays contacts (not shown) are used to control a lock or bolt mechanism (also not shown).

A "channel" consisting of a two input AND Gate G3, of which the output (pin 3) is connected to the input pin of NAND Gate G1, is provided for each input. Only one such channel is shown in the diagram but it is to be understood that eight such channels are provided. One input (pin 1) of each AND Gate G3 is directly connected by a line to the connector for the setting card 8 and the other input (pin 2) is indirectly connected, via an inverter I, by a line to the plug-in board connector.

Both lines are each connected by a pull-up resistor R to a Hi line (+5 volts) so that, normally, the input on pin 1 of AND Gate G3 is Hi and that on pin 2 is Lo, due to the inverter I. Thus each input to NAND Gate G, is normally held Lo.

The connector for the setting card 8 provides separate connections for each of the eight output lines a, b, C, d, e, f, g and h from the key socket 6; for each of the eight paired line channels 1 a and 2a, 1band2b, 1cand2c, 1dand2d, 1eand2e, lfand2f, 1g and 2g and 1h and 2h to the respective inputs of NAND Gate G1; and for a connection to the Lo line for the circuit.

The plug-in setting card 8 is an interchangeable printed circuit capable of providing an electrical connection between a respective one of the key socket outputs and one or the other of the two lines for each corresponding logic circuit input channel a, b, c, d, e, f, g or h and between line 2 of any of the input channels and the circuit Lo line. Thus it is possible to provide an electrical connection from each element of the key to the respective input of AND Gate G3. As the pull-up resistors hold each line of each input channel Hi, one internal connection of a key element to the common ground effectively, on insertion of a key 1 into the socket 6, inputs a Lo signal to that input line, whilst an isolated key element will effectively input a Hi signal.

For the electronic lock to operate, both the inputs to AND Gate G3 have to be driven Hi, i.e.

the input lines 2 have to be driven Lo while input lines 1 remain Hi. This is achieved by particular keys 1 and setting cards 8 in combination. Where a key-element is connected to the circuit Lo level, the card connects the respective socket output to the line 2 input of the respective input channel.

Where the key-element is isolated, the card connects the line 2 input of the respective input channel to circuit Lo level and connects the respective socket output to the line 1 input of the respective input channel. Although this last connection is not needed operatively it is necessary so that if the respective channel is brought Lo by use of a wrongly coded key, that particular input is disabled. It also ensures that a Hi level is always present at all the key socket contacts to prevent measurement by a probe in the key socket being used to determine the connections of the plug-in card 8 and hence the signal combination needed to operate the lock, and it also prevents the lock from being operated by insertion of a bar to short between all the contacts, this action would drive a line 1 input Lo if connected "across" the card 8 and inhibit NAND Gate G1.It is deer that a different card 8, having different connections, is needed to complement each key pattern. Changing the combination for the lock is achieved by simply changing the setting card.

In the example shown in Fig. 3, the key pattern is =Lo, b=Hi, c=Hi, d=Hi, e=Lo, f=Lo, g=Lo and h=Hi and the complementary connections for card 8 that are needed to "match" the key combination are: Key socket output .. connected to . . Channel input a 2a b lb c 1C d 1d e 2e f 2f g 2g h 1h Additionally, connections of the following channel inputs to Lo are required: 2b, 2c, 2d and 2h.

A power supply, not shown, is included to provide power for the logic circuit, the output circuit and the lock mechanism; either from "mains" or from an external or internal battery.

A manual override button 11 is supplied as a connection between input pin 1 2 of NAND Gate G2 and circuit Lo. In the "locked" state, the input to pin 1 3 of NAND Gate G2 is Hi, operating switch 11 bypasses resistor R and drives input pin 12 Lo, giving a Hi output signal on pin 11 to turn transistor Tr on and thus operate the relay Ry. An alternative position for override switch 11 is shown (in dotted line) to be directly connected between the Lo (0 volt) circuit line and the relay Ry.

An alternative form of setting unit is shown by Fig. 4 to be another pen-shaped key, to fit a mating socket (not shown); this setting key having 24 ring elements in eight groups of three and a central conducting core 12, the socket having a separate contact for each ring element and the metal key body. The ring elements may either be of "single" width 1 3 or of "double" width 1 4 to bridge between selected adjacent pairs of socket contacts. As before, insulating bushes 1 5 serve to isolate particular ring elements from the core 12 and insulating washers 1 6 to isolate the ring elements from one another and the key body.

It is possible with such a setting key to provide all the key-complementary interconnections needed. The part key shown in Fig. 4 has connections to correspond with those of the circuit of Fig 3. Output lines a, b, C, are shown connected to one "side" of the key with the paired line channels connected to the other side of the key. As shown, key socket output a is connected to channel input 2a; output b to input 1 b and output c to input 1 c. Inputs 1 a and 1 C are isolated from the core 12 whilst input 2b is connected to the core and thence to circuit Lo.

The invention is not limited to the use of a single key to one lock, any number of keys either serially connected to a single setting unit or in parallel with each key having its associated setting unit could be used. Both cases increase the number of possible combinations for any one lock. Alternatively, or additionally, the number of channels in the lock could be increased.

Claims (9)

Claims

1. A lock and key combination comprising a key having a plurality of electrically conductive and electrically non-conductive elements arranged in a predetermined pattern, and a lock including means for producing a signal from each of said elements, the state of the signal being dependent upon whether said element is electrically conductive or electrically nonconductive, transformation means for effecting a predetermined transformation of the states of said signals to produce a plurality of further signals, detecting means for producing a given output signal at a given state of said further signals most suitably when and only when said further signals have the same predetermined state as each other, and locking means arranged to be operated by said output signal.

2. A lock and key combination that comprises a key having a plurality of conductive elements arranged in a predetermined conducting pattern and a lock having a signal generator producing a parallel set of signals, a release unit that produces a signal for release of a bolt or other detent only on receipt of a certain, unlocking, parallel arrangement of signals, a setting unit having a plurality of conductive elements the conducting arrangement of which is settable in a pattern complementary to that of the key, and means to convey in parallel the set of signals from the generator to the release unit via the key and setting unit and whereby the arrangement of the signals determined by the pattern of the one is converted into the unlocking arrangement by the pattern of the other.

3. A lock and key combination according to claim 2 wherein i) the key has the plurality of electrically conductive elements on a surface thereof and insulated one from the other, with each element insulated from or electrically connected to a common conductor for the key, a particular key having a selection only of the elements connected to the common conductor, to accord with the predetermined pattern; ii) a socket is provided to receive the key and make separate electrical contact with each of the elements and a common conductor, and has a series of outputs each corresponding with a respective one of the key element contacts or with the common conductor contact; iii) the release unit includes an electronic logic circuit the elements of which are connected to have a number of inputs and an output from which the release signal issues; and iv) the setting unit is changeable and is connected between the outputs of the key socket and the inputs to the logic circuit.

4. A lock and key combination according to claim 3, wherein the logic circuit is a binary circuit having means to hold all the inputs to one logic level, corresponding to the locked condition, and the common conductor output from the key socket is connected to the other logic level whereby, on insertion of a key in the socket, the logic circuit inputs connected via the setting means to a key element itself connected to the common conductor are driven to said other logic level.

5. A lock and key combination according to claim 4, wherein the logic circuit has a pair of inputs, of which one is inverting, corresponding to each key element and the internal connections of the setting unit additionally enable all the key element socket contacts to be at the same logic level.

6. A lock and key combination according to any preceding claim, wherein the key is cylindrical with a series of electrically conducting ring elements.

7. A lock and key combination according to any preceding claim, wherein an alarm is connected to the lock to be triggered if the lock is not relocked within a predetermined period after opening.

8. A lock and key combination according to any preceding claim, wherein a delay is built in between insertion of a key into the lock and the lock's response.

9. A lock and key combination substantially as herein described and shown in the drawings.