GB2197379A - Electric security lock - Google Patents

Abstract

A security circuit assembly comprising a sensor 20 designed for location in a fixed position, a plurality of exposed contacts a,b,c... on the sensor with a first one a of such contacts connectable to a circuit input and a second one h of such contacts connectable to a circuit output, an activator, Fig. 2, designed to be portable by a user, a plurality of exposed contacts A,B,C,... on the activator, indicator means on at least one of the sensor and activator showing a plurality of acceptable positions in which the activator can be presented to the sensor with contacts of the activator engaging contacts of the sensor, and conductor means between at least two contacts of the activator and effective in a given one only of said acceptable positions to complete a circuit between the first and second contacts of the sensor. The circuit comprises a battery 24 and solenoid 25 for effecting withdrawal of a bolt. The circuit may also include an alarm 26 which is activated if the activator is presented to the sensor in an incorrect attitude. <IMAGE>

Description

SPECIFICATION Security circuit assembly This invention relates to a security circuit assembly that may be used to enable any required piece of equipment.

For example, the equipment to be enabled may be a lock on a door providing access to premises, motor vehicles, safes and so forth or may be electrical, electronic or mechanical means, the enablement of which will allow operation of a piece of machinery or other equipment.

In the domestic field the most common locking and unlocking function is that associated with doors giving access to premises.

Locks on such doors are usually actuated by keys turned to open or close a latch member.

Moving parts within such locks eventually wear, and a further disadvantage of such locks is that if the key is lost a need is usually felt to change the lock in order to preserve security of the premises. Similar- problems are experienced with keys for arming and disarming security installations such as domestic or vehicle burglar alarms.

In order to avoid mechanical wear there have been proposals in the past for magnetically or electrically operated switches, capable of operation by an appropriate activator to give an output signal that may enable the controlled equipment. For example, a signal may energise a solenoid to effect withdrawal of a latch.

One such electrically operated switch is described in EP-A-0125848. In this arrangement a portable activator is provided that is removably receivable by a sensor associated with the equipment to be enabled. The activator has a surface with a planar array of electrically conductive paths thereon, some paths being electrically isolated from others, and the sensor has at least two contacts for engagement with said electrically conductive paths in order to close a circuit between the contacts when the activator is received in the sensor. Means are provided for guiding the activator relative to the sensor so that it is presented in the correct position, and the correct activator so presented will complete the circuit and enable the equipment.Should a different activator be presented the circuit will- not be completed, and indeed an alarm circuit may alternatively be operated, so giving a warning that unauthorised operation is being attempted.

In this prior arrangement unauthorised enablement of the equipment is thus prevented if the incorrect activator is presented. However, if by theft or otherwise the correct activator falls into the hands of some unauthorised per son then all he has to do is to present the activator to the sensor and thereby enable the equipment. The present invention seeks to overcome this disadvantage and provide a security circuit which makes unauthorised use extremely difficult, while avoiding moving parts and allowing simple manufacture.

According to the invention a security circuit assembly comprises a sensor designed for location in a fixed position, a plurality of exposed contacts on the sensor with a first one of such contacts connectable to a circuit input and a second one of such contacts connectable to a circuit output, an activator designed to be portable by a user, a plurality of exposed contacts on the activator, indicator means on at least one of the sensor and activator showing a plurality of acceptable positions in which the activator can be presented to the sensor with contacts of the activator engaging contacts of the sensor, and conductor means between at least two contacts of the activator and effective in a given one only of said acceptable positions to complete a circuit between the first and second contacts of the sensor.

It will be seen that in order to effect unauthorised enablement of the equipment it is necessary not only for the unauthorised person to come into possession of the correct activator for a particular sensor, but also for him to present the activator to the sensor in the single correct one of the plurality of acceptable positions. The additional security given in this way will readily be appreciated.

It will be understood that the sensor and activator may be of any convenient shape and size, and that the possible contact arrangements thereon are virtually unlimited. It is, however, preferred that the pattern of contact engagement between the sensor and the activator is substantially identical in every one of the acceptable positions, in order to make it impossible for an unauthorised user to deduce the correct acceptable position from the contact layout.

The indicator means may be simple markings on the sensor and activator. For example, each of the sensor and activator may be marked with a series of consecutive numbers and an authorised user of the assembly will merely have to remember which number of the activator needs to be placed in correlation to which number of the sensor. Obviously, letters, colours or other markings may be used in place of numbers, and equally obviously it is not necessary for both the sensor and the activator to carry a full series of markings. A simple arrow or single mark on either the sensor or the activator may suffice to facilitate presentation in the correct acceptable position.

In order to reduce the possibility of misalign ment guide and guideway arrangements may be provided on the sensor and activator, alignment of the guides and guideways being possible in each of the acceptable positions.

Depending on the shape and configuration of the sensor and activator the exposed con tacts may be located on one or more of a surface, an edge, a projection on or a hole in the respective member, and the contacts themselves may be of any suitable size or shape, which may differ between sensor and activator, or indeed may differ on the sensor itself or on the activator itself.

The conductor means on the activator may be such that when the activator is in the correct acceptable position the required circuit is made directly between the first and second contacts of the sensor. Alternatively, the conductor means may be such that, in conjunction also with conductor means between appropriate contacts on the sensor, the required circuit is made through any selected number of contacts on the sensor and activator.

Contacts on the sensor other than those required to complete the circuit output that will enable the equipment may be usable to operate an alarm or disenabling system if the activator is presented to the sensor in any of the acceptable positions other than the correct one. Additional security is thereby provided as an alarm is given on the first incorrect presentation of the activator to the sensor.

For use as a domestic lock the sensor may be built into a self-contained unit that will also comprise a battery, a solenoid controlling the position of a latch, and an alarm if required.

Such a unit may readily be assembled so that it is of a size to replace an existing mechanical lock.

In order that the invention may be better understood specific embodiments of security circuit assemblies in accordance therewith will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic front elevation of a sensor and associated circuitry; Figure 2 and 3 are respectively rear and front elevations of an activator for use with the sensor of Fig. 1; Figures 4 and 5 are similar to Figs. 1 and 2 respectively showing a different arrangement of sensor and activator; Figures 6 and 10 are a selection of sketch views showing other contact arrangements that may be made in sensors and activators according to the invention.

Fig. 1 shows a sensor 20 for a security circuit assembly, the sensor being designed for location in a fixed position, for example to form a lock for a door. The sensor has a castellated rim comprising a plurality of raised portions, shown as 1 to 12, and a corresponding plurality of grooves. Lying radially inwardly of each raised portion is an exposed contact, the twelve contacts being shown as a to m. A selected three of the contacts, a, h and I are respectively electrically connected to terminals 21 to 23 which are in practice con cealed at the back of the sensor rather than at the sides thereof as shown for convenience in the Fig. The three terminals may be connected respectively to a battery 24, a solenoid 25 controlling movement of a latch and an alarm 26.The entire assembly of sensor, battery, solenoid and latch arrangement and alarm may be incorporated in a common housing secured to a door in much the same way as a conventional lock, so that only the front face of the sensor as shown in Fig. 1 is visible from the front of the door.

Figs. 2 and 3 show an activator usable with the sensor of Fig. 1. The activator has a front face 27 from which projects a finger grip 28, and a rear face provided with two projections 29, 30 capable of being received in any diametrically opposite pair of grooves of the sensor 20. Additionally, the activator has a cutout window 31 through which the numbered projections of the sensor may be viewed. On the rear surface of the activator there is arranged a plurality of exposed contacts A to M arranged in a configuration identical to the configuration of contacts a to m on the sensor. Selected ones of the contacts A to M are electrically connected by conductors in any suitable pattern, the pattern of conductors shown in broken lines in Fig. 2 being merely one example.The activator will be moulded or otherwise manufactured in such a way that the conductors are not open to view and such that the lines of the conductors cannot be detected otherwise than by destruction of the activator.

Use of the activator in conjunction with the sensor will be apparent. The activator is presented to the sensor with its rear face towards the sensor and it may be located in any one of twelve acceptable positions wherein the projections 29, 30 will locate in diametrically opposite grooves of the sensor.

On being presented in any acceptable position and pushed towards the sensor the contacts A to M of the activator will make contact with the contacts a to m of the sensor. The circuits completed thereby will depend on the respective angular orientation of the activator and sensor. Thus, if the activator is presented to the sensor in the correct position where the numeral 12 is visible through the window in the actuator a circuit from the battery to the solenoid is completed through contacts a, A, H and h. The solenoid is activated and a latch controlled thereby can be withdrawn so that the door may be opened. It is only in this position that such activation will occur. In other positions, namely those where the numeral 2, 6, 9, or 11 is visible through the window in the activator a circuit will be completed between contacts a and I on the sensor so energising the alarm 26 to give warning of an attempt at unauthorised operation. In the remaining acceptable angular positions no activation of either the solenoid or the alarm occurs.

Referring now to Fig. 4 this shows an alternative form of sensor comprising a disc 40 with a plurality of locating pins 41 projecting from the face thereof. Between each adjacent pair of pins is a contact pair such as 42, with one contact of each pair being electrically connected to a common terminal 43 for connection to a battery 44. Of the other contacts of each pair that for pair 44 is connected to a solenoid 45 and that for pair 46 is connected through a timer 47 to a relay RA having nor mally open contacts RA1 in a line between the solenoid and the battery. The other contacts of all remaining contact pairs are connected to a terminal 49 connected to an alarm 50.

The rear face of an activator 51 usable with this sensor is shown in Fig. 5. The activator is in the form of a disc having two holes 52 capable of receiving two diametrically opposite pins so that the activator may be presented to the sensor in any one of twelve acceptable positions. A conductive region 53 forming two electrically connected contact regions is provided on the face 51. The activator may have a window similar to that of the activator of Fig. 2, through which may be viewed numerals or other markings formed on the sensor between adjacent pins 41.

The operation of the embodiment of Figs. 4 and 5 differs from that of Figs. 1 and 2 in that it is necessary to effect two correct presentations of the activator to the sensor in order to energise the solenoid. The first correct presentation requires that the conductor 53 be presented to bridge the contact pair 46, so closing a circuit to the timer 47. The relay RA is held energised for a period controlled by the timer, and during this energisation period contacts RA, are closed. During the period of energisation the activator must be removed and then presented so that the conductor 53 bridges the pair of contacts 44 in order to complete a circuit to the solenoid 45 in order to open the latch. It will be noted that only a limited time is allowed for this second operation, and that successful operation will not take place if the contacts are made in the reverse order.It will also be clear that if the activator is presented in any other angular position the conductor 53 will bridge a pair of contacts other than pairs 44 and 46 and so complete a circuit to the alarm 50.

The principle illustrated by this embodiment may be extended, so that more than two correct presentations of the activator to the sensor may be necessary in order to energise the solenoid.

The embodiments so far described show only two of the enormous number of contact arrangements that may be utilised. Figs. 6 to 10 show schematically other possible arrangements, while limitless others will suggest themselves to one skilled in the art. Figs. 6 to 10 make no attempt to show any connections between individual ones of the contacts shown therein, but it will be understood that connections may be made as and where required and that activators will be designed accordingly with appropriate contact arrangements and connections. The electrical path required to be completed for successful operation may be as simple or as complex as required, requiring completion only through one pair of contacts as shown in the Fig. 4 embodiment, or requiring completion through any number of engaging contacts as required.

Precoded sensors and appropriate activators may be factory made and supplied as a combination to the end user. Alternatively, activators and sensors may be provided with the means for the user either to effect his own coding by completing connections between selected contacts or by severing existing connections between contacts.

Although sensors and activators of disc form are shown in the drawings it will be appreciated that other shapes can be used. It will also be understood that guide and guideways arrangements other than the castellations and pins described may be utilized, and indeed guides and guideways may be omitted completely, so leaving it entirely up to the user to achieve the correct alignment. Although numerals are shown on the sensor 20 to facilitate alignment it will be understood that these may be replaced by any other suitable form of marking.

The electrical circuits to which the sensors are connected may be as simple or as complex as required to achieve the desired operating effect. It may be preferable to arrange that many or all of the individual contacts of the sensor exhibit identical electrical characteristics to any test instrument that may be presented thereto, so making it virtuaily impossible for anyone to break the coding of the circuitry.

It will be clear that two or even more security circuit assemblies may be integrated into a single circuit, so that correct operation of both sensors, for example by independent holders of different activators, is required. For additional security, rather than sound an alarm, or in addition to the giving of an alarm, the circuit may be designed to operate a deadlock or simply to fuse and so deadlock the existing latch if any incorrect presentation of the activator is made to the sensor. Many other possibilities will be apparent.

Claims (5)

1. A security circuit assembly comprising a sensor designed for location in a fixed position, a plurality of exposed contacts on the sensor with a first one of such contacts connectable to a circuit input and a second one of such contacts connectable to a circuit output, an activator designed to be portable by a user, a plurality of exposed contacts on the activator, indicator means on at least one of the sensor and activator showing a plurality of acceptable positions in which the activator can be presented to the sensor with contacts of the activator engaging contacts of the sensor, and conductor means between at least two contacts of the activator and effective in a given one only of said acceptable positions to complete a circuit between-the first and second conacts of the sensor.

2. An assembly according to claim 1 in which the pattern of contact engagement between the sensor and the activator is substantially identical in every one of the acceptable positions.

3. An assembly according to claim 1 or claim 2 in which guide and guideway arrangements are provided on the sensor and activator, alignment of the guides and guideways being possible in each of the acceptable positions.

4. An assembly according to any one of the preceding claims in which contacts on the sensor other than those required to complete the circuit output that will enable the equipment are connectable to operate an alarm or disenabling system if the activator is presented to the sensor in any of the acceptable positions other than the correct one.

5. An assembly according to any one of the preceding claims, for use as a door lock, in which the sensor is built into a self-contained unit that also comprises a battery, a solenoid controlling the position of a latch, and an alarm.