GB2250539A - A keyhole security unit - Google Patents

Abstract

The security unit is arranged to be fitted over the keyhole on a strongroom door to prevent unauthorised access to the lock. The security unit comprises a housing (2, 4) through which a passage (12, 14) extends. A shutter (16) is mounted in the housing and in its normal position obstructs the passage (12, 14) and hence access to the lock. When it is required to have access to the lock, a push-button (38) is pressed to close a switch and thereby apply electrical power to a time delay circuit. After a time determined by the time delay circuit, the electrical power is connected to a solenoid (32) upon operation of the push-button (38). Upon energisation, the solenoid (32) retracts its plunger (30) whereby the spindle (18) can be rotated by a knob (54) to allow access to the lock. The security unit can be retro fitted to existing locks, and delays access thereto to deter criminals. <IMAGE>

Description

A SECURITY UNIT The present invention relates to a security unit for mounting over a fastening device for controlling access to that fastening device.

It is not uncommon for criminals to force hostages to open the door of a safe or strongroom to gain access to its contents. It is known that this situation can be alleviated if immediate access to the safe or strongroom is not available. It is for this reason that many modern safes are fitted with time locks so that they can be opened only at specified times. A criminal is often deterred from proceeding if he discovers that he will have to wait for several minutes or longer before access to the secured property can be gained.

However, time locks have to be incorporated in the door or fastening device of the safe or other protected property and it is difficult, and therefore not usual, for such time locks to be retro fitted.

According to the present invention there is provided a security unit for mounting over a fastening device for controlling access to the fastening device, said security unit comprising a housing having opposed front and rear surfaces and a passage extending through said housing and opening in both said front and rear surfaces for rendering a fastening device adjacent the opening in said rear surface accessible from said front surface by way of said passage, and said security unit further comprising a shutter mounted within said housing for movement between a normally closed, first position in which said shutter extends across, and obstructs, said passage and a second position in which said shutter is withdrawn out of said passage so that the passage is not obstructed, and control means within said housing for enabling movement of the shutter from its first position to its second position.

A security unit of the invention may be a selfcontained unit which can be mounted over an existing fastening device, for example, a keyhole or other access for a lock. The shutter normally obstructs the passage, and hence prevents access to the fastening device.

Preferably, said control means is arranged to enable movement of the shutter out of its first position only after a preset delay.

In a preferred embodiment, the control means comprises means to prevent movement of said shutter out of its normally closed, first position. The control means also comprises means to release said movement preventing means under specified conditions. Preferably, the specified condition is that a predetermined time has elapsed after release of said preventing means has been requested.

Means for determining the time delay and the movement preventing means may be embodied in any required manner.

For example, the time determining means may be a mechanical timing device or an electrical circuit. Where the time determining means is implemented by electrical means, it is preferably arranged for the movement preventing means to be electrically released. For example, the shutter may be electrically powered both to enable and prevent movement thereof. Thus, a motor may be provided for moving the shutter, and may be arranged to be demagnetised or otherwise held in the normally closed position of the shutter.

For many applications, the security unit needs to be completely stand alone. This means that if any of its components are to be electrically powered, this will be by battery power. In this circumstance, the components are arranged so that the drain of battery power is kept as low as possible. For example, the means for preventing movement of the shutter is preferably mechanical. The timing means may be electrically powered and, at the end of the preselected delay period, able to enable release the movement prevention means. However, in this embodiment, movement of the shutter itself would preferably by mechanical means.

In a preferred embodiment, the shutter is mounted on a spindle for rotation about the spindle axis. Preferably, the spindle is off centre relative to the shutter so that the shutter is urged towards its normally closed, first position by gravity. Additionally and/or alternatively, biasing means may be provided to bias the shutter towards its normally closed position.

The means to prevent movement of the shutter from its normally closed position preferably comprises extensible means of a solenoid, or of an electro-mechanical device, or of an electro-magnetic device. The extensible means is arranged to mechanically engage the spindle, or the shutter, or engaging means carried by the spindle or the shutter Preferably, the extensible means is extended when the solenoid or other device is not energised, and may be retracted by applying electrical power to the solenoid or other device.

In an embodiment, an electrical time delay circuit is housed within the housing and is arranged to selectively connect electrical supply terminals, to which a battery may be connected, to the solenoid or other electro-mechanical or electro-magnetic device. Actuation of the time delay circuit may be arranged to enable the connection of the supply terminals to the solenoid or other device after a delay determined by said time delay circuit.

Preferably, the spindle is arranged to extend relative to the front surface of the security unit. When power is applied to the solenoid or other device, the extensible means may be retracted, and the shutter can then be moved to its second position by rotation of the spindle.

In an embodiment, the rotation of the spindle is arranged to be performed manually, and indicating means are provided to give a warning signal, which may be visual or audible, when power is applied to the solenoid or other device.

Although it is preferred for many applications that the unit be battery powered, it is also possible to connect the unit to a mains power source. This may be done, for example, if the unit is connected to an alarm circuit.

The shutter preferably comprises a sturdy plate, for example of steel. This is to prevent or deter attempts to damage the plate through the opening in the front surface of the housing.

The housing of the security unit preferably has a back plate in which the opening in said rear surface is provided. The back plate may be generally planar and is arranged to be fastened to a support, such as a door or other closure member, so that said opening is over the fastening device to be protected. In this case, the fastening device would be flush with its support. However, where the fastening device to be protected is proud of, or otherwise projects, from its support the back plate may be recessed to receive the fastening device with said opening provided in the recess. It will be appreciated that an example of a flush fastening device is a keyhole for a lock, whereas a push-button operated security lock normally stands proud of its support.

The housing is preferably formed to have a cover member arranged to be engaged on the back plate. The back plate may be fastened to the cover member by screws or other fixing means applied through the back plate into the cover. In this instance, once the security unit is fastened to a support, the fixing means are inaccessible unless the security unit is removed from the support.

The shutter, its control means, and any power supply are housed within the housing, and therefore the cover member preferably comprises a front plate formed with an upstanding perimetral rim.

The housing, with its enclosed components, is fixed to the support of the fastening device to be protected so that the opening in the rear surface is adjacent that fastening device The passage through the housing then allows access to the fastening device from the front surface of the housing so long as the shutter is not obstructing the passage.

The security unit may be fixed to the support by fixing means, such as by way of a plurality of socket head screws. When the heads of the screws are removed, a criminal requiring to remove the security unit has to unscrew all of the plain headed screws, an operation which can take a considerable time.

Preferably, the front surface of the cover member is provided with a recess in which a battery is housed for connection to the electrical supply terminals within the housing.

For appearance, and again to provide delay to any criminal who wishes to obtain access, a fascia member is preferably provided to fit over the housing. The fascia member may comprise a fascia plate having an upstanding perimetral rim and is arranged over the security unit when fixed in position. Preferably, the fascia member is fixed by appropriate fastening means to the housing, and this again provides a delay to any criminal.

An embodiment of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an exploded perspective view of a security unit of the invention, Figure 2 shows a plan view of the front of a cover member of the unit of Figure 1, and Figure 3 shows a section through the security unit.

The security unit shown in the drawings is particularly arranged to be fitted over the keyhole on a door or other closure member (not illustrated) to prevent unauthorised access to that keyhole, and hence to a lock securing that closure member. Generally, the closure member will be the door of a safe or strongroom.

The security unit comprises a back plate 2 which is fixed to a cover member 4 to provide a housing in which the components of the security unit are housed. In this respect, it will be seen that the cover member 4 comprises a front plate 6 from which an upstanding perimetral rim 8 extends. The back plate 2 engages within the free edge of the rim 8 and is then fixed to the cover member 4 by way of screws or other fixing means (not shown) which are applied through screws holes 10. It will be appreciated that once the security unit is secured to a strongroom door or the like, access to the screws extending through the holes 10 will be denied. The back plate 2 and the cover member 4 are made of a strong material, for example, of aluminium.

An aperture 12 is formed in the back plate 2 and is arranged, when the security unit is in position, to be placed over the keyhole of the strongroom door. A corresponding aperture 14 is provided in the cover member 4. In the housing, the two apertures 12 and 14 are aligned whereby a passage is defined to extend through the housing and to open in both the front and rear surfaces thereof by way of the apertures 12 and 14. Thus, so long as the passage is not obstructed, access to the keyhole of the strongroom door can be had therethrough.

The housing mounts a shutter 16, preferably in the form of a steel plate, which is arranged in its normal position to obstruct the passage through the housing. As can be seen in Figure 1, a spindle 18 is fixed to the shutter plate 16 and projects relative to the front surface of the housing through an aperture 20 formed in the front plate 6. The spindle 18 is provided off centre of the plate 16 such that gravity assists in returning the plate 16 to its normally closed position The spindle 18 extends through the plate 16 and at its rear carries a boss 22. As is clearly shown, this boss 22 is arranged to be received within a cylindrical bore 24 formed in a mounting block 26.

In this respect, the boss 22 is provided with an indent 28 and, in the normally closed position of the plate 16, a plunger 30 of a solenoid 32 engages within the indent 28.

It will be seen that the mounting block 26 has a through bore 34 therein which is aligned with the apertures 12 and 14 to define the passage through the housing.

It will be apparent that when the plate 16 is in its normally closed position, as shown in Figures 1 and 3, it completely obstructs the passage through the housing.

Furthermore, because the plunger 30 is engaged within the indent 28, rotation of the spindle 18 to move the plate out of this position is not possible. The only way in which the plate can be moved is by withdrawing the plunger 30 and this can only be done by applying electrical power to the solenoid 32.

The security unit shown in Figure 1 is arranged to be powered by a battery and in this respect, the front plate 6 is provided with a recess 36 in which a battery can be mounted. This battery is thereby connected to an electrical circuit (not shown) which is housed within the security unit. The electrical circuit is preferably provided on a printed circuit board, and is arranged to connect the battery to the solenoid 32 by way of a time delay circuit (not shown) including switch means and a manually operated switch. The manual switch is actuated by a push-button switch 38 mounted on the front plate 6 of the cover member 4.

In use, the security unit illustrated is fixed to the strongroom door to be protected such that the passage through the housing is over the keyhole thereof. Thus, access to the keyhole is allowed if the shutter plate 16 is moved such that it does not obstruct the passage. The unit is fixed to the door by way of a number of bolts, screws or the like which are applied through holes 40 therefor extending through the cover member 4. It is most important that a plurality of such screws or bolts are provided so that if a criminal requires to remove the unit, it takes time. It will be seen that in the embodiment illustrated, eight holes 40 to receive eight screws or bolts are provided. Similarly, it is preferred that the screws are socket head screws such that their heads can be removed once the unit has been secured. Again, this makes it more difficult, and therefore more time consuming, to remove the unit once fitted.

Preferably, once the unit has been fitted a fascia member 42 is arranged thereover and secured by appropriate fixing means (not shown). It will be seen that this fascia member has a fascia plate 44 from which extends an upstanding perimetral rim 46. The fascia plate is provided with three apertures, the first of which, an aperture 48, is aligned with, and the same size as, the apertures 12 and 14 in the housing. The aperture 48 therefore allows access to the passage through the housing, and hence to the keyhole being protected. The fascia plate 44 also has a second aperture 50 in which the push-button 38 appears.

Finally, the fascia plate 44 has a central aperture 52 through which the spindle 18 projects. A knob 54 is keyed onto the spindle 18.

When it is required to have access to the keyhole protected by the security unit, the push-button 38 is pressed to close the manually operable switch. This applies electrical power to, and therefore initiates, the time delay circuit. Preferably, an audible warning circuit is also provided to provide audible confirmation to the user that the switch was closed by pressing the push-button 38. Once initiated, the time delay circuit provides a predetermined delay which may be, for example, anything from one minute to sixteen minutes. At the end of this time, the time delay circuit connects the electrical supply to the solenoid 32 by closing its switch. The closure of the time delay switch is also arranged to generate an audible warning signal. At this time, it is only necessary to press the push-button 38 again to close the manual switch to complete the circuit to the solenoid 32.The solenoid 32 is thereby energised and withdraws its plunger 30 whereby the spindle 18 is released for rotation. The spindle 18 can therefore be rotated by way of the knob 54, and hence the plate 16 can be moved, clockwise in the embodiment shown, so that it does not obstruct the passage through the housing. A key can then be inserted through the passage into the keyhole and the lock operated in the normal manner.

The time delay circuit is arranged to connect power to the solenoid 32 only for a predetermined time, and then it opens its switch. Opening of the time delay switch removes power from the solenoid 32, which is no longer energised, and hence its plunger 30 is extended. Of course, the plunger 30 will only be able to engage once more in the indent 28 in the boss 22 if the indent 28 is aligned with the plunger. If a key is still in the passage through the housing, for example, it will prevent return of the plate 16 to its normally closed position. However, if there is no key in the passage, or it is removed, gravity, and a return spring 56 will rotate the plate 16 anticlockwise back to its obstructing normally closed position.In this respect, one end of the return spring 56 is connected to the mounting block 26, and the other end is connected to the plate 16 such that the spring biases the plate 16 towards its normally closed position.

It will be appreciated that if the battery fails, or is removed, the plate 16 cannot be moved out of its normally closed position and thus that the unit is fail safe. The battery can be replaced simply by removing the fascia member 42.

The security unit of the invention does not prevent access to the keyhole it protects, but does delay that access for the preset period. In many hostage situations, this delay will deter the criminal. The preset period determined by the time delay circuit is adjustable during manufacture and setting up of the unit, but is not adjustable in use.

The embodiment illustrated is battery powered and therefore self-contained, and for most applications this is generally preferred. However, if there is an alarm circuit, the unit could be connected to receive power from the alarm circuit. More sophisticated versions could be arranged to trigger the alarm if the security unit is activated to allow access to the keyhole at a time when the alarm is switched on. In these circumstances, additionally and/or alternatively, anti-tamper sensors may be fitted to the unit, for example, to sound an alarm if the unit is removed from the door on which it has been fixed.

It will be appreciated that variations in and modifications to the unit described may be made within the scope of this application.

Claims (19)

1. A security unit for mounting over a fastening device for controlling access to the fastening device, said security unit comprising a housing having opposed front and rear surfaces and a passage extending through said housing and opening in both said front and rear surfaces for rendering a fastening device adjacent the opening in said rear surface accessible from said front surface by way of said passage, and said security unit further comprising a shutter mounted within said housing for movement between a normally closed, first position in which said shutter extends across, and obstructs, said passage and a second position in which said shutter is withdrawn out of said passage so that the passage is not obstructed, and control means within said housing for enabling movement of the shutter from its first position to its second position.

2. A security unit as claimed in Claim 1, wherein said control means comprises means to prevent movement of said shutter out of its normally closed, first position, and means to release said movement preventing means under specified conditions.

3. A security unit as claimed in Claim 2, wherein the specified condition is that a predetermined time has elapsed after release of said movement preventing means has been requested.

4. A security unit as claimed in Claim 2 or 3, wherein said means to release said movement preventing means comprises means for determining a time delay and enabling means responsive to the determination of said time delay for enabling the release of said movement preventing means.

5. A security unit as claimed in any of Claims 2 to 4, wherein the shutter is electrically powered both to enable and prevent movement thereof, and wherein said movement preventing means is arranged to be electrically released.

6. A security unit as claimed in Claim 5, wherein a motor is provided for moving the shutter, and is arranged to be demagnetised or otherwise held in the normally closed position of the shutter.

7. A security unit as claimed in any preceding claim, wherein said shutter is mounted on a spindle for rotation about the spindle axis.

8. A security unit as claimed in Claim 7, wherein said spindle is off centre relative to the shutter so that the shutter is urged towards its normally closed, first position by gravity.

9. A security unit as claimed in Claim 7 or 8, wherein biasing means are provided to bias the shutter towards its normally closed position.

10. A security unit as claimed in any preceding claim, wherein said control means comprises means to prevent movement of said shutter out of its normally closed, first position, and wherein said movement preventing means comprises extensible means of a solenoid, or of an electromechanical device, or of an electro-magnetic device, said extensible means being arranged to mechanically engage the shutter, or a spindle on which the shutter is mounted, or engaging means carried by the spindle or the shutter.

11 A security unit as claimed in Claim 10, wherein said extensible means is extended when the solenoid or other device is not energised, and is arranged to be retracted by applying electrical power to the solenoid or other device.

12. A security unit as claimed in Claim 10 or 1S, further comprising an electrical time delay circuit housed within the housing and arranged to selectively connect electrical supply terminals, to which a battery may be connected, to the solenoid or other electro-mechanical or electromagnetic device, wherein actuation of the time delay circuit is arranged to enable the connection of the supply terminals to the solenoid or other device after a delay determined by said time delay circuit.

13. A security unit as claimed in Claim 12, wherein said spindle is arranged to extend relative to the front surface of the security unit such that when power is applied to the solenoid or other device, the extensible means are retracted, and the shutter is moved to its second position by rotation of the spindle.

14. A security unit as claimed in Claim 13, wherein the rotation of the spindle is arranged to be performed manually, and indicating means are provided to give a warning signal when power is applied to the solenoid or other device.

15. A security unit as claimed in any preceding claim, wherein said shutter comprises a sturdy plate, for example of steel.

16. A security unit as claimed in any preceding claim, wherein the housing of the security unit has a generally planar back plate in which the opening in said rear surface is provided, said back plate being arranged to be fastened to a support so that said opening is over the fastening device to be protected.

17. A security unit as claimed in Claim 16, wherein said housing is formed to have a cover member arranged to be engaged on the back plate, and wherein the back plate is fastened to the cover member by screws or other fixing means applied through the back plate into the cover.

18. A security unit as claimed in Claim 17, wherein said shutter, its control means, and any power supply are housed within the housing, and wherein the cover member comprises a front plate formed with an upstanding perimetral rim.

19. A security unit for mounting over a fastening device substantially as hereinbefore described with reference to the accompanying drawings.