A widespread and serious problem in hotels, blocks of flats and other similar publicly accessible places, is that opportunist thieves can easily walk into such premises during a quiet period and force entry into several locked rooms and walk away with any valuables inside without being detected.

These types of"kick-in"incidents represent a serious crime problem for which there is currently no inexpensive and effective solution.

GB-A-2083858 describes a keeper of a mortice lock having a pressure-sensitive electrical alarm switch mounted on the outside of a keeper wall that lies in the path of the lock bolt on forced opening movement of the door. The keeper is fixed to a striker plate that has transversely elongated screw holes to secure the keeper to the door jamb. Because of the elongation of the holes, when pressure is applied to the door to try to force it open while the lock bolt is seated in the keeper, the striker plate and keeper can move sufficiently to bring the switch against a side face of the mortice in the door jamb and so cause the alarm switch to operate. This arrangement requires a carpenter fitting the keeper and striker plate to the door jamb to take care to ensure that the mortice in the door jamb is accurately positioned and that the keeper striker plate is not only accurately positioned but also is screwed to the jamb with just the right amount of tightness. Moreover, if the screws loosen during use of the door, the arrangement becomes unreliable.

GB-A-2159866 discloses a Yale lock in which an opening force applied to a door, which is locked by a bolt of the lock projecting into a keeper, causes an angled bracket mounted in the keeper to pivot about a fulcrum provided by the junction of a thrust plate and a back plate thereof

against the action of a leaf spring acting between the back plate and a mounting plate of the keeper. As a result, a microswitch carried by the bracket is correspondingly pivoted so that it is actuated, to initiate an alarm, by reaction of an arm of the microswitch against a front plate of the keeper. The device is applicable also to a keeper of a mortice lock, where the keeper is sunk into the door frame, or to the keeper of a manually slidable door bolt. The leaf spring, which acts to prevent the giving of false alarms, is exposed to being disabled. Moreover, correct operation of the microswitch is dependent upon correct operation of both the angled bracket and the microswitch arm.

GB-A-2054227 discloses an intruder alarm which includes a microswitch disposed within a latch portion of a door lock.

A spring steel plate disposed obliquely within the latch portion and fixed along one edge has its opposite free edge separated by a short distance from a switching member of the microswitch. A latch bolt extends into an aperture of the latch portion when the door is closed and, in the event of an attempt to force the door open, bears upon the plate and displaces it sufficiently to actuate the switching member and thereby an audible alarm before entry is forced. A screw extends through a bar and engages the plate so that a minimum force required to actuate the switching member may be varied.

Similar arrangements may be provided for a door bolt and socket and for a padlock and hasp assembly. The spring and the microswitch are exposed to being disabled.

FR-A-2277215 discloses a lock in which, when in a locked position, a bolt enters an opening in an inner wall of a keeper. The keeper is fixed in place by at least four screws on its upper and lower parts and by a further two screws which are inserted through an extended wall of the keeper, the extended wall being sunk into a groove in the door frame.

If an attempt is made to force the lock by inserting a lever between the frame and the door, the door moves and the bolt tilts, thus compressing cellular insulating material and

thereby closing a pair of electrical contacts to complete an alarm circuit. It appears that the tilting of the bolt results in distortion of a wall of the keeper to compress the insulating material and thus closing of the contacts.

FR-A-2294298 discloses a lock with built-in alarm which is operated when the door is forced. The lock is of the type with a bolt sliding into a keeper to lock, and has a switch within the keeper with contacts brought together and the alarm effected by a horizontal force applied to the door. The keeper constitutes an open-ended box which is spring-mounted to shift laterally within a fixed casing, and the lateral motion of the inner box, under horizontal forces transmitted via the bolt and against the springs, causes the contacts to close. Alarms can be of the sonic or visual type.

FR-A-2376932 discloses a lock or latch which includes a detector mechanism which gives warning of illegal entry. The mechanism is built into a keeper and comprises an elastic electrically-insulating buffer and an electric contact. The buffer normally prevents contact, but yields under pressure on the door until the bolt effects a contact. An electrical circuit is then completed and an alarm sounds. The detector can be appended to existing locks. The buffer may comprise a tubular rubber cap with one end closed, fixed by its open other end to an internal wall of the keeper, and is positioned so as to be opposite the bolt when the bolt enters the keeper. The contact is mounted inside the closed end of the cap. The contact and the keeper may be connected to a live wire and an earthed wire, respectively.

In FR-A-2539449 a keeper of a door lock mechanism is held in place by two screws. The keeper is attached to the two screws by a piece of spring steel. The two screws pass through the ends of the spring steel, and a central bolt attaches the spring to the keeper. A microswitch is mounted in the keeper. If pressure is applied to the door, and hence to the bolt within the keeper, the spring allows a small amount of movement of the keeper away from the door frame. A

button or lever which operates the microswitch is arranged to sense this and change the switch state.

WO-A-96/07806 discloses an alarm-triggering closure device for a door or window which has to be made secure. The device has a first fastening device which must be breached by force, a second fastening device which must also be breached by (greater) force, and means for triggering an alarm in the event that the first fastening device is breached. If the first fastening device has been breached, the movement of the locking device in the opening direction of the door or window is restricted by the second fastening device. The first fastening device is formed by metal fittings mounted or incorporated in the door or window, and the second is an auxiliary fastening mounted on the door or window. At least one sealing section engages behind or in at least one opposing stop element when locked, and, once the first fastening device has been breached and the door or window panel has subsequently opened to a predetermined extent, the sealing section moves with a lateral retardation against the opposing stop element to restrict the opening movement. Once the first fastening device has been breached, an alarm, such as a silent alarm, is transmitted by radio or telephone.

According to one aspect of the present invention, there is provided apparatus comprising a keeper for a lock and for mounting on one of a surround of an opening and a panel for obturating said opening, said keeper serving to receive a locking member for mounting on the other of said surround and said panel and for engaging in said keeper to retain said panel in an obturating position, and a sensing device arranged to sense movement of said locking member towards a wall of said keeper which wall lies in the path of said locking member on forced opening of said panel.

Owing to this aspect of the present invention, less skill is required to fit the apparatus.

The panel can be, for example, a door or a window.

According to a second aspect of the present invention,

there is provided a system comprising a surround of an opening, a panel for obturating said opening, and a sensing device for sensing attempted forced opening of said panel, and a telephone line electrically connected to said sensing device for communicating an attempted forced entry signal from said sensing device.

Owing to this aspect of the present invention, since the enclosed spaces to be protected will usually have existing telephone lines already installed, this system provides a cheap and convenient way of protecting those enclosed spaces.

In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 shows an exploded perspective view from above of part of a mortice lock, Figure 2 shows a rear elevation of that part, Figure 3 shows a side elevation of that part, and Figure 4 shows a schematic arrangement of an hotel having a series of alarmed doors.

Referring to Figures 1 to 3, the mortice lock includes a keeper in the form of a unitary part 2 to be fixed to a door jamb. The part 2 comprises a sheet metal fixing plate 4, a sensor-activating, sheet metal piece 6, a staple-like, sheet metal piece 8 and a sensor-carrying, sheet metal piece 10.

The staple-like piece 8 is attached, to the rear of the fixing plate 4 by any convenient means, such as welding or bolting, the shape of the edge 12 corresponding to that of the edge 20 of the plate 4. The piece 8 is also attached to the upper surfaces of flanges 18 of the sensor-carrying piece 10 by any convenient means, such as welding.

The sensor-activating piece 6 is located in the gap formed between the lateral portion 22 of the staple-like piece 8 and the surface 24 of the sensor-carrying piece 10 and forms a cavity into which the locking bolt of the mortice lock fits. The sensor-activating piece 6 is not fixed

relative to the items 4,8 and 10, but allowed a limited degree of lateral to-and-fro movement within the gap in which it fits. The outer surface of the lateral wall 26 of the sensor-activating piece 6 thus lies close to, but does not touch, a pair of sensors 28 attached to the inside surface of the lateral wall 24 of the piece 10, the sensors being electrical pressure switches. The piece 10 also has an undulating leaf spring 30 attached to the inside surface of its wall 24 by clips 32, which are formed from stamped portions of the piece 10. The piece 6 also comprises a slightly curved planar striker plate 36 which projects in the opening direction of a door (not shown) and allows the locking bolt to be guided into the mortice cavity. The fixing plate 4 has a plurality of holes in order that the part 2 can be attached, by using screws, to the door jamb. In effect, the items 6,8 and 10 constitute a keeper with a cavity bounded by them and containing a sensing device constituted by the wall 26 and the sensors 28 and sensing movement of the locking bolt towards the wall 24.

Once fitted, the part 2 forms part of an effective door alarm system. When a forced opening of a locked door fitted with the part 2 is attempted, the locking bolt, engaged in the cavity, is forced against the inner surface of the lateral wall 26 of the activating piece 6, which causes the piece 6 to move in the direction of the opening of the door.

The outer surface of the lateral wall 26 makes contact with the leaf spring 30 and then, against the action of the spring, with the sensors 28. The leaf spring 30 provides resistance to the movement of the piece 6 such that the sensors 28 are not activated simply by someone knocking on a door or the wind blowing against the door. A more significant force is required to ensure that the sensors 28 are activated, such as that created by an attempted forced entry.

Contact with either of the sensors 28 produces an alarm signal to indicate an attempted forced entry. Once the opening force on the door is removed, the leaf spring 30

returns the activating piece 6 to its original position. An advantage of having the spring 30 between the activating piece 6 and the wall 24, with the striker plate 36 substantially covering the gap therebetween is that, once the unitary part 2 is installed in the door frame, the spring 30 is not exposed to disabling. An advantage of having the piece 6 slidably movable in the installed unitary part is that, upon attempted forcing of the door, the microswitches 28 are operated before any member of the part 2, except for the spring 30, is bent by the force applied and the spring is of course designed not only to undergo such bending but also to return to its original shape after bending. Thus, after even a large number of forced entry attempts on a particular door, there is no need for a locksmith to be called in to restore the alarmed mortice lock to an original condition. An advantage of having the locking bolt acting directly on the switch-activating piece 6 which itself directly acts on the microswitches 28 is that the number of moving parts is minimised and there is little to go wrong, which is highly desirable in alarm systems, which should always operate when needed but not operate unnecessarily. An advantage of having two microswitches, one at each end of the length of the unitary part 2, is that an alarm will still be activated even if the part 2 is installed at a slight angle to the vertical plane of the door and thus wrongly.

Referring to Figure 4, an effective door alarm system, which will detect any attempt to force an entry is now described. An hotel, or other building which requires many rooms to remain locked for security purposes, may have the part 2 fitted to the door jambs of each of a series of room doors 40. One of the rooms is shown to an increased scale.

The sensors 28 shown in Figures 1 to 3 are wired locally via an alarm transmitting unit 42 to a convenient telephone extension point 44. The system is wired in parallel with any telephone handsets 54, so the hotel room telephone extension can still be used to make and receive calls as normal. The

sensors 28 detect any attempt of a forced entry which creates a signal which is in turn transmitted to the unit 42. The unit 42 transmits the signal, via the telephone socket 44 within the hotel room, to the hotel's existing telephone network 46 and subsequently to a dedicated telephone socket 48 at a remote location from the room being broken into, such as the hotel reception.

A monitoring station 50 at that remote location instantly alerts hotel staff to any attempt at a forced entry and also the location of the door 40 being forced. The station 50 preferably includes an LCD (Liquid Crystal Display) or similar graphic display of alarm states and locations. It also preferably includes a loud alarm sound emitter to alert staff instantly to the occurrence of a forced entry attempt. The station records electronically the times and dates of all alarms. This information is useful as evidence against perpetrators of forced entry attempts, especially if used in conjunction with other security systems, for example CCTV (Closed Circuit Television) cameras covering reception areas or exits. The station 50 continuously monitors the status of all doors 40 equipped with the parts 2. The proper authorities, such as the Police, can then be immediately notified of an attempted forced entry whilst that attempted break-in is occurring.

In an alternative embodiment, the alarm transmitting unit 42 and the extension point 44 can be combined as a single unit serving both as an alarm transmitting unit and a telephone extension point, with the room telephone extension plug being insertable into a socket on the single unit. This single unit can be of the same size and shape as a standard double electrical wall socket.

If required, a local alarm sounder 52 can also be fitted in close proximity to the door 40, which, when activated during an attempted forced entry, may act to discourage a potential thief from further action. This local alarm sounder 52 can be made particularly effective in frightening a

perpetrator away if it makes an audible pre-recorded announcement.

Instead of, or in addition to, the item 52 being a local alarm sounder, it can be an"alarm active"indicator fitted to the external part of the door frame to act as a deterrent.

This indicator may incorporate a flashing LED and a bleeper which are activated when the alarm is triggered. The indicator has two functions, namely to discourage potential thieves from any further action which might cause damage to the door and to provide a local alarm to attract the attention of any passers-by.

The alarm system can be developed to use a telephone autodialling unit. When activated by the sensors 28 the autodialler will call a pre-programmed telephone number and make a recorded announcement giving the location of a potential break-in. Alternatively the alarm transmitting unit can incorporate a digital modem via which it is able to communicate digitally with a digital modem in the remote monitoring station 50. When activated, the alarm transmitting unit automatically dials a dedicated telephone number of the line to which the station 50 is connected. The station 50 detects the incoming call and having established a telephone connection the station 50 transmits a digital code so that the alarm transmitting unit knows that it has successfully contacted the station 50. If the unit does not receive this code within a preset time in seconds, it will redial the station 50 until it receives the correct digital code. This procedure acts as a failsafe in the event of the telephone line of the station 50 being'busy'because another alarm transmitting unit is reporting an alarm, or in the case of a faulty telephone connection. In the event of several simultaneous alarm events this'handshake'procedure ensures that all the transmitting units that have been activated will report the event to the monitoring station in sequence, because each transmitting unit will repeatedly dial the monitoring station until it receives the code to confirm a

successful communication. After the confirmation code has been received the alarm transmitting unit digitally transmits the location and nature of the alarm, which is then displayed on the LCD at the monitoring station 50.

Through the use of automatic dialling, the forced entry attempt and its location will be reported almost instantaneously, thus saving vital seconds and increasing the likelihood of taking effective action against the perpetrator.

If desired, the connection cable between the keeper 2 and the alarm transmitting unit may incorporate an anti- tamper loop. If the connection between the two devices is cut or disabled in any way, by accident or design, the transmitting unit will communicate this as an alarm to the monitoring station 50, which will display an appropriate message.

When the alarm transmitting unit is transmitting an alarm event, it may draw the necessary electrical power from the open telephone line; however a small battery is included to provide the relatively small amount of power to initiate the call. The type of battery used may typically last for a period in excess of fifty years. However, if a battery should become faulty (which will be symptomised by reduced voltage), the monitoring station will detect the reduced voltage in advance of the battery becoming unserviceable and communicate this to the monitoring station which will display an appropriate message for a member of staff to remove a cover of the alarm transmitting unit and replace the faulty battery.

In the event of an alarm the transmitting unit still operates even if the room telephone has been left off the hook. However, a programmable delay can be added to this feature, in case a person inside the room may be telephoning for help because someone outside is trying to break in. If the alarm transmitting unit is triggered and it detects that the telephone is off the hook, it can wait for a pre-defined period (45 seconds for example) before taking control of the

telephone line and initiating communication with the monitoring station 50.

It is also possible to provide an interface (via a series of relay closures for instance) which will enable the monitoring station 50 on receiving an alarm to provide signals to activate other security devices such as CCTV (Closed Circuit Television) equipment in the location of the alarm. These activation signals can be programmed to be appropriate to the location of the alarm received. For instance, an alarm received from any room on a 3rd floor would activate the CCTV system on that floor.

This product presents a very cost-effective solution to break-ins such as hotel"kick-in"incidents, since installation requires no significant structural wiring or building work. It uses the existing door locking mechanisms and the existing wiring infrastructure and includes a keeper 2 of external size and shape corresponding to those of a conventional keeper, and can therefore be installed quickly with minimum disruption. For instance, rooms in an hotel could be fitted with the system during the hotel's cleaning cycle. In addition, the alarm system works automatically. It is armed as soon as the door is locked, and requires no further action from the person (s) occupying the room.