GB2519212A

GB2519212A - Locking mechanism

Info

Publication number: GB2519212A
Application number: GB1414538.7A
Authority: GB
Inventors: Clive Stone
Original assignee: PRIMERA LIFE Ltd
Current assignee: PRIMERA LIFE Ltd
Priority date: 2013-08-16
Filing date: 2014-08-15
Publication date: 2015-04-15
Anticipated expiration: 2034-08-15
Also published as: GB201314658D0; GB2519212B; GB201414538D0

Abstract

A locking mechanism having a drive unit arranged to operate a locking mechanism on a closure, the drive unit having a drive securing mechanism comprising a rotatable body and a number of locking elements 36, the locking elements being biased (preferably via compression springs 83 Fig 7) into a flush position with an external cover 4 that is mounted in use to the external face of the closure. In use a key engages with the locking elements and pushes them into the drive unit and clear of the cover, allowing rotation of the drive unit to move the lock into an unlocked position. A central key guide locator 34 may also be provided. Also claimed is a key for the locking mechanism comprises a stem having spigot members arranged to pass through an aperture in the cover to cooperate with the locking elements 46. Preferably the lock is an anti-ligature lock.

Description

LOCKING MECHANISM

This invention relates to an improved locking mechanism.

S It is desirabk in at least some situations to have a locking mechanism that is blind on one side of a door to which the locking mechanism is fitted and cai be operated by a key that is simple and low cost. Typically an institution can have a nlLmber of such keys so reducing the problem of having to find a "master key". In use the locking mechanism is blind on a patient's side of the door and so cannot be tampered with when the patient is in the room, as may be the case if the patient has to be locked in the room, A common problem with locking mechanisms of any kind in mental health institutions is that the patients can tamper with the mechanism and attempt to prevent operation of the locking mechanism by the introduction of foreign objects such as chewing gum or toilet paper. The patient may wish to prevent access to the room by clinical staff and this is a serious safety issue given the potential for sdf-harm in such environments.

To overcome the problem outlined above some existing locking mechanisms have been designed to have an open keyway and to be open" on the staff side of the door.

The use of an open keyway has been intended to aflow easy remova' of foreign objects inserted in the keyway. These mechanisms are invariably very simple and therefore of low security which can easily be manipulated even with the simplest of tools. It is desirable therefore to provide a lock which prevents the insertion of foreign bodies and which has a higher level of security in preventing operation of the lock by unauthorised persons.

It is also desirable to be able to provide a locking mechanism that is tamper resistant.

According to a first aspect of the invention there is provided a locking mechanism adapted and arranged to be insertable in a closure in use, and wherein the locking mechanism is operable from a first side of the closure and has a cover arranged to be fitted to the first side of the closure. the locking mechanism being engageabk with a locking means and having a drive means arranged to drive the ocking means in use; the drive means comprising a drive unit, arranged to operate the locking means, and a drive securing means, the drive securing means being biased away from the drive unit and towards the cover and arranged to be operable by a key, S According to an aspect of the invention a ocking mechanism is provided which is arranged to be fitted to a closure in use, the locking mechanism being operable from a first side of the closure and having: a drivc means arrangcd to be insertcd in the closure and a fixable cover comprising a front face and a rear portion arranged to be mounted on the first side of the closure over the drive means, the drive means being arranged to engage with a locking means in the closure and able to move the locking means in use between an open position and a locked position wherein the drive means comprises a drive unit arranged to operate the locking means and a drive securing means wherein the drive securing means comprises a rotatable body which in use is concealed by the cover and a number of locking elements ocated in the rotatabk body and biased away from the drive unit towards the cover, the cover having at kast one aperture in which the locking elements are received such that a first end of each locking element is substantially flush with a front face of the cover in a first secured position, the locking mechanism being arranged to be operable by a key to move the locking elements against the bias towards the drive unit to a second active position in which the key is able to rotate the drive securing means such that the drive unit can move the locking means between the open and the closed position.

It is desirable that the cover is fixed to the closure so that the drive securing means and the drive unit are enclosed behind the cover and within the closure and cannot be accessed. Preferably the key way and the drive unit are not accessible to a person intent on tampering with the lock. The cover may also be regarded as a housing surrounding an opening in the closure and protecting the drive means from tampering.

Preferably the cover is arranged to meet standards for anti-ligature locks. The cover is preferably arranged such that there are no ligature points and the tolerances are such that a ligature cannot be inserted into the cover. It is also desirable that the locking elements are flush with the front surface of the cover. If the locking elements are recessed there is a possibility of a foreign body being jammed in the recess and preventing operation of the locking mechanism. On the other hand if the locking elements extend substantially beyond the front of the cover there is a possibflitv of a ligature point being created.

S It will be appreciated that in the area of mental health it is important to ensure that patients are not able to tamper with the locks on doors, either to prevent thcm being opened or to prevent a door from being locked. It is a common problem in such situations that patients can insert foreign objects into a keyway in order to prevent the operation of a ock, Foreign objects may be items such as chewing gum or todet paper. It is also known for patients to try to operate a lock with an implement that may be found in the room or surroundings, A particular advantage of the invention is that the locking elements are biased towards the cover such that the first end of the locking element is flush with the front face of the cover. As the first end is flush with the front face of the cover there is no obvious opening in which a foreign object can be readily inserted. It is possible that a foreign body may be pushed into the aperture in the cover by pushing against the first end of the locking element, Preferably the bias of the locking elements towards the cover is arranged to be sufficiently strong that any object inserted into the aperture will be ejected by the locking element when pressure on the object is released.

Prcferably the locking mechanism is arranged such that the lock cannot be operated by an implement found in the room or surroundings and can only be operated by a specific key which is avaflabk to staff members, It will be appreciated that the locking means may be conventional, In some cases the locking means may bc in the form of a latch or dead-bolt that is operated to move outwardly of the closure and engage with a strike plate mounted on a frame surrounding the closure. The atch or dead-bolt may be operated by a spindle that extends through a closure and be rotated by the drive means to either lock or un'ock the closure, The spindle may be a standard square spindle or spindles having other cross sections may be used. The locking means may also be sash locks.

Preferably the drive means is arranged to drive the spindle and may be arranged to rotate the spindle when the key operates the locking mechanism. In some embodiments the spindle may extend into and be directly engaged by the drive means.

Tn some embodiments the locking mechanism is blind on a second side of the closure.

In some embodiments a means for operating the locking means is provided on a second side of the closure. The locking mechanism may be provided with a handle on the second side of the closure. The handle may be arranged to operate the locking mechanism. In a preferred embodiment the locking mechanism comprises an override mechanism such that the handle can operate the locking means. The drive means may preferably be arranged to override operation of the locking means.

In a preferred embodiment the cover is adapted to be fitted to the first side of the closure and comprises a face plate and a key way provided in the cover. Preferably the cover comprises at least one aperture. In a preferred embodiment the cover comprises a number of apertures arranged to receive and cooperate with corresponding projections on the key. The cover may comprise an escutcheon.

In a particularly preferred embodiment the cover comprises an escutcheon with an aperture having a generally circular shape and a number of radial extensions, as will be described below in more detail.

Preferably the drive securing means comprises a number of locking elements biased away from the drive unit. Preferably each locking element is arranged to be received in a corresponding aperture in the cover. The locking mechanism is preferably provided with a number of elements corresponding to one or more apertures in the cover. In a preferred embodiment the locking elements comprise locking pins. The locking pins are biased toward the front face of the cover and are located in the at least one apertnre when the locking mechanism is in the first secured position.

Preferably the locking mechanism cannot be operated as the drive securing means, formed by a sub-assembly of the locking mechanism is arranged to be unable to rotate.

Consequently the drive ILnit cannot be rotated and the locking means cannot be operated.

In one preferred embodiment the drive unit comprises a body having a first end and a second end, The second end is preferably arranged to receive a spindle connected to a locking means which may be in the form of a latch, dead-bolt or other locking means.

The first end of the body may have a chamber into which the one or more locking elements can be received when the locking elements are moved to the second active position, The body can be rotated by the key and can rotate the spindle and drive the latch, dead-bolt or other locking means.

Biasing means are provided which bias the locking elements or locking pins away from the drive unit and towards the front face of the cover. In a preferred embodiment the biasing means are compression springs, Preferably the locking elements are dimensioned such that a front face of each locking element is flush with an outer surface of the cover, In a preferred embodiment the biasing means are located in a respective channel in the body, each channel having an outer end aligned with a respective aperture in the cover and an inner end, remote from the cover. Each channel is preferably provided with a shoulder at the outer end. In a preferred embodiment the compression springs are arranged to act on a rear face of the locking elements, preferably in the form of locking pins. The compression spring preferably also acts on an end of the respective channel, Preferably the locking elements have an outvard1y expanding rim that abuts the shoulder at the outer end of the channel. It is desirable that the rim and shoulder interact to prevent the locking pins from extending beyond the front surface of the cover. It will be appreciated that if the pins were to extend beyond the front face of the cover a ligature point would be created.

A key guide or key locator guide may also be provided. In a preferred form the key locator guide may be provided in the form of a central locator or button in the drive securing means. The key locator guide may be provided adjacent the locking elements. The key locator guide is preferably arranged to be biased away from the drive unit and is desirably movable from a forward position in the secured position to one in which the key locator guide is received at least partially in the drive unit and the drive securing means and the drive unit can be rotated in the active position.

In one embodiment the locking mechanism may be provided with one. two, three, four, five or more locking elements and corresponding apertures in the cover, The locking elements may comprise a central element which forms the key locator guide and a number of radial locking elements. In a preferred embodiment there is provided a centr& element in the form of a key locator guide button and four radial locking elements in the form of locking pins.

S Preferably there is a plurahty of locking elements. The locking dements may be the same or may have different shapes. In a preferred embodiment the central element may have a shaped periphery and the radial locking elements may be the same or different. In a preferred option the radial locking elements may have a circular periphery and be formed as locking pins. The central element or pin may have a uniquely configured periphery such as an octagonal shape. In an alternative preferred embodiment the radial locking pins may be square or angular and the central locking pin or key guide may be round. The key locator guide button may be provided with one or more ocating projectiosn which may provide angu'ar ocation of the key guide within the drive unit.

As has already been described the cover is provided with an aperture. Preferably the aperture is generally circular and arranged to receive the key ocator guide. In a preferred embodiment the circular aperture has a number of radial extensions arranged to receive the locking elements, in a particularly preferred embodiment the aperture is arranged to be generally circular with four radial extensions each sized to receive a locking pin provided adjacent to the key locator guide.

Preferably each locking pin is arranged to be adjacent to the key locator guide such that the key ocator guide and the locking pins extend through the same aperture in the cover. Preferably the aperture and the locking pins are shaped such that the drive securing means cannot be rotated when the locking pins extend through the aperture in the secure position.

It is desirable that each of the locking pins has to be moved towards the drive unit against the bias in order for a key to disengage the drive securing means from the cover and for the key to engage the drive unit and operate the locking means to move between the locked position and the open position.

In a preferred embodiment respective biasing means are arranged to eject any foreign object inserted into an aperture, Preferably the compression springs are sufficiently strong that if a foreign object is inserted into any one of the apertures the respective compression spring will act on the respective locking pin or key locator guide to push the foreign object out of the aperture in the cover, in this way the locking mechanism has an auto ejecting function which prevents damage to the operability of the locking mechanism as a result of tampering by the patient.

Additionally it is advantageous that the locking mechanism cannot be operated unless all of the locking elements arc simultaneously moved against the biasing mcans. The security of the locking means has been increased as it is much more difficult for a patient to tamper with the locking mechanism and lock or unlock a door or other closure. Preferably the locking mechanism is arranged such that the locking means can be operated only when all of the locking elements are simultaneously moved against the action of the biasing means and disengage from the apertures in the cover allowing the subassembly of the drive securing means to rotate and operate the drive means.

In a preferred embodiment the biasing means are provided within the drive means and the locking elements arc received in a space in the drive means when the locking elements are moved against the bias and into a position in which the drive means can be moved.

Preferably the locking mechanism is arranged such that projections extending radially from the stem of a key head rotate the sub-assembly of the drive securing means behind the cover, It will be realised that the key may be positively held in the locking mechanism by the projections when the lock is partially rotated. Desirably the key may be removed from the cover only when the projections are aligned with the extensions in the aperture.

According to another aspect of the invention there is provided a lock for a door comprising a locking means, a locking mechanism in accordance with an aspect of the invention and a key in accordance with another aspect of the invention and arranged to operate the locking mechanism.

According to a second aspect of the invention there is provided a key arranged to operate the locking mechanism of the first aspect of the invention.

The key may comprise a handle and a shaft and a key head known as a key bit, Preferably the key bit is provided with a number of projections arranged to cooperate with the respective apertures in the cover and to engage with the locking elements of S the drive securing means. It is desirable that the key bit can be introduced to the cover and the projections act on each of the locking elements to move each respective locking element against the action of the biasing means. Once each of the locking elements preferably in the form of locking pins, has been moved against the bias the key bit can engage and rotate the drive means and operate the locking means. If the handle is held on the second side of the door the locking means is preferably arranged to override the action of the handle to unlock the door, According to another aspect of the invention there may be provided a key arranged to operate a locking mechanism according to the aspect of the invention wherein the key comprises a handle, a shaft and a key head and wherein the key head flLrthcr comprises a number of extending projections arranged to cooperate with the respective apertures in the cover and each extending projection is arranged to act on and move a respective locking element located in the respective aperture such that the respective locking elements can be moved against the bias towards the drive unit such that the drive unit can move the locking means between thc open and the closed position.

In a particularly preferred embodiment thcrc is provided a key arranged to operate a locking mechanism according to the aspect of the invention wherein the key comprises a handle, a shaft and a key head and wherein the key head comprises a stem having a number of radially extending spigot members spaced around the stem and adapted to engage the respective locking elements.

Preferably the spigot members are spaced from the key head byi distance at least as great as a thickness of the cover, Preferably the stem comprises a central key locator adapted to engage and locate with the key locator guide and is further provided with a number of projections spaced around the key locator and arranged to cooperate with the respective apertures on the cover, Preferably each projection is in the form of a spigot member extending from a central stem. Once the spigot members are received wholly within the drive member the drive member can be rotated relative to the cover and the locking means can be operated.

It will be appreciated that in order for the drive unit to be operated, each of the S locking elements has to be moved against the bias such that the ocking elements are clear of the cover and additionally the spigot members are received in the drive securing means clear of the cover. The spigot members are able to engage with the drive securing means in the channel and to transmit a drive force to the drive securing means in order to rotate the sub assembly and consequently rotate the drive unit and operate the locking means.

In use the spigot members can be inserted in the corresponding apertures and act on the first end of the locking elements. Once the locking elements have been displaced from the apertures and into a body of the drive means the spigot members can act on a face of the respective channel to rotate the drive means and operate the locking means.

According to a third aspect of the invention there is provided a kit of parts comprising at least one of: a locking mechanism in accordance with the first aspect of the invention, and a key in accordance with the second aspect of the invention.

According to a fourth aspect of the invention there is provided a method of locking a closure comprising fitting a locking mechanism according to the first aspect of the invention in the dosure, fitting the cover to a first side of the dosure. introducing a key according to the second aspect of the invention to the locking mechanism and engaging the drive securing means and moving the drive securing means towards the drive unit and operating the locking means to lock the closure.

Preferably the locking dements are moved against the bias and the drive unit is rotated relative to the cover and operates a locking means mounted within the closure.

It will be appreciated that the locking mechanism may be used in conjunction with a number of other conventiona' articles of door and window furniture such as handles, occupancy indicators, viewing panels and removable door stops. These may in some embodiments be combined with the plate having the cover for the key way, The locking mechanism may desirably be used in a number of applications and it may be particulady desirable if one key may be used to operate a number of different locking mechanisms used on differing articles of door and window furniture. For example the lock may be used to secure viewing panels and removable door stops. The locks may S also be used for window closures and for panels securing artic'es such as TVs, It may be desirable to have a single key that is arranged to operate thc lock for a number of closures.

Preferably the key may be introduced to the ocking mechanism such that projections on the key can act on a first end of the locking elements. The projections move the locking elements away from a front face of the cover and the locking elements and the proj ections locate in a channel in the drive unit allowing the drive unit to rotate relative to the cover, The key can be rotated when the projections are positioned behind the cover. The key may be removed when the projections are in line with the apertures in the cover.

In one embodiment the cover is provided with four equi-spaced apertures and the key is provided with four corresponding radially extending projections. It will be appreciated that the key can be removed from the locking mechanism in any one of four orientations of the key. In other embodiments the aperture may be provided with 2. 3, 5 or more extensions to the aperture and the key is provided with a corresponding number of radially extending projections. The number of aperture extensions and projections selected may be dependent on the locking means or on other factors. It may be advantageous to be able to remove the key from the lock in a number of orientations and facilitate use of the locking mechanism.

The invention will now be described by way of example only with reference to the accompanying drawings iii which: Figure 1 is a view of a prior art locking mechanism fitted to a dosure; Figure 2 is a perspective view of a drive securing means of a locking mechanism in accordance with the invention; Figure 3 is a perspective view of a cover; Figure 4 is a side view of key in accordance with a second aspect of the invention; S Figure 5 is an exp'oded view of the ocking mechanism and key from a first angle; Figure 6 is an exploded view of the locking mechanism and key of Figure 5 from a different angle; and Figure 7 is an exploded view of the drive means.

Figure I illustrates a known dosure I having a ocking means 2, a locking mechanism generally indicated at 3 and a cover 4 fitted to a first side 6 of the closure 1 A handle 8 is fitted to a second side 10 of the closure and is connected to a locking means of the ocking mechanism. The locking mechanism further comprises a drive means 12 arranged to drive the ocking means 2. The drive means comprises a drive unit and a drive securing means.

The invention is shown ill Figures 2 to 7, and modifies various parts of the prior art closure of Figure I. The drive securing means 20 is shown in more detail in Figure 2 and comprises a fixing plate 22 having a central upstand 24 through which a boss 26 extends. The boss 26 comprises a shaped aperture 28 having a circular centre 30 and square extensions 32 extending radiafly from the periphery of the circu'ar aperture. A circular element in the form of a circular locking pin 34 projects through the circular centre 30. Four square locking pins 36 project radially through the extension 32 of the aperture. Each of the locking pins 34 and 36 is biased away from the locking means and towards the cover 4 on the first side of the closure.

The cover 4 will now be described in more detail with reference to Figure 3 in which the cover 4 comprises an escutcheon 4ft The escutcheon 40 also comprises a sloping edge shield 42 and the cover 4 is fixed to the closure by means of fixings located in fixing apertures 44. The drive securing means extends through an orifice 46 in the escutcheon 40, The circu'ar pin 34 projects through the orifice 46 and projects slightly therefrom, The square pins 36 each extend through square extensions 48 of the orifice. The biasing means biases the square pins forwards to be flush with a surface 50 of the escutcheon.

An exploded view of the locking mechanism is shown in Figure 5. The cover 4 has S angkd sides such that the cover does not provide a ligature point. In this embodiment the cover has a central orifice 46, having a circular periphery and four radially extending extensions 48. Fixing holes 44 are also provided and these receive a screw or other fixing means in order to sccure the covcr in a fixed position to a first side of a closure on which the cover is mounted, The closure may be a door or a viewing panel or other furniture, such as a removable door retainer for a door or frame.

As best seen in Figure 7, each locking pin 36 has a first end 51 and a second end 53 and a rim 55 extends from the locking pin 36 at the second end 53, The circular pin 34 acts as a key locator guide or button and has an upstanding peripheral wall 57 and a ccntral dcprcssion 59. The ccntral depression is arrangcd to reccivc an end 64 of the key 52 and to locate the key 52 in position on the cover 4. The circular key locator guide 34 is also arranged to have ocating extensions 61 which in this case are located at a second end of the key locator guide 34 and are provided to secure the key locator guide in position in the drive securing means, It will be appreciated that the kcy locator guide 34 extends outwardly from the cover and is arranged to havc sloped and chamfered edges 50 so that a hgature point is not created, Preferably the key locator guidc 34 extcnds only a short distancc beyond the front face 81 of the cover 4.

The peripheral wall 57 of the key locator guide 34 is in part aesthetic but also aids location of the key 52 on the cover 4, The drive securing means has been described in relation to Figure 2 and is shown in an exploded view in Figure 7. It is worth noting that the upstand 24 is circular and able to rotate with the opening 30 in the fixing plate 22. The drive securing means also comprises a boss 26 which is rotatable within the fixing plate 22, The drive unit comprises a body 63 having a central chamber 65 and a number of channels 67 extending outwardly from the central chamber and arranged to cooperate with the locking pins 36. A compression spring 83 located on a shaft 85 is also located in each channel 67 and arranged to act on a base 69 of the drive unit to bias the locking pins 36 away from the base 69 and towards the cover 4, A central compression spring 87 is provided that acts between the base 69 and the circular key locator guide 34, A ocating dirnpk 89 is provided on the floor of the central chamber 65 to locate the spring biasing the central key locator guide. The boss 26 is also arranged to be connected to the body 63 and to rotate with the body 63.

Each rim 55 on the locking pins 36 is arranged to engage with a respective shoulder on a rear face of the boss 26. Each channel 67 in the body 63 is sized to allow the locking pins and thc rims thcrcof to slide within thc channel 67. The rims 55 cannot pass the rear face of the boss and so the locking pins 36 are securely retained in the drive securing means. Additionally the location of the rims 55 is such that the locking pins 36 cannot extend outward of the front face 81 of the cover 4 and so cannot provide a ligature point.

The body 63 is additionally provided with a number of longitudinally extending recesses 91 providcd in the chamber 65 and arranged to rcccive thc corrcsponding locating extensions 61 on the circular pin key locator guide 34.

It will be apprcciated that alternative forms of drive unit may be readily envisaged by the skilled person and that other forms of biasing may be selected.

A key 52 in accordance with an aspect of the invention is iflustrated in Figure 4, The key comprises a handle 54 and a shaft 56 extending therefrom. A head of the key known as a key bit 58 is connected to a distal end 60 of the shaft 56. The handle 54 is arranged to be easily grasped and rotated, The key bit 58 comprises a body 71, a stem 62 from which a central boss 64 extends from an end face 66, Four spigot members 68 of square cross-section extend radially from the stem 62, In use the key bit 58 is inserted into the locking mechanism such that the central boss 64 and the spigot members 68 are inserted into the orifice 46 and abut the central key locator guide 34 and square locking pins 36, Pressure on the handle of the key moves the key bit 58 into the orifice 46 depressing all of the locking pins 36 and the key locator guide 34 50 allowing the drive locking means to be disengaged and the drive unit to be engaged. The drive unit can be rotated and the locking means moved from a locked to unlocked position or vice versa.

The spigot members 68 are spaced from the body 71 by a distance which is greater than a thickness of the cover, Once the spigot members 68 have depressed the locking elements 36 against the bias of the compression springs 83 sufficiently that the spigots members 68 are within at least the drive securing means the drive unit is able to be S rotated by the key engaging with and rotating the drive securing means. It will be appreciated that the cover 4 has an aperture 46 having a symmetrical arrangement and the key 52 may be inserted in any one of four orientations. Similarly the key 52 may be rcmoved in any one of four orientations. It is envisaged that a lock could also be arranged to be provided with three apertnres or more than four apertures, so providing different levels of symmetry.

The drive securing means is arranged such that the drive unit cannot be engaged and rotated unless all of the locking pins are moved against the biasing force of the compression springs.

It will be appreciated that the compression springs bias the locking pins forward to be flush with the surface of the cover. In the event that a patient tries to tamper with the lock and insert a foreign object into the lock it will be found that this is difficult as the locking pins are biased forward and once the depressing force is removed the compression springs will cause the locking pins to move forwards again and eject the foreign body. In addition it will be appreciated that the drive unit cannot be rotated unless all thc locking pins are deprcssed thus making it difficult for thc lock to be tampered with or opened without the correct key.

An additional advantage of the locking mechanism is that there are no open cavities in which a foreign body can be lodged and the chamber in which the locking pins and the spigots of the key are received is a closed chamber that is not accessible to a patient.

In the case of an emergency a staff member can introduce a key to the lock from a first side of the closure and can rotate the key to open the lock, The key head is introduced to the cover 4 and the boss 64 on the stem of the key head locates in the depression 59 on the key locator guide 34. The key is rotated to bring the spigot members 68 into line with the locking pins 36 and the key 52 can then be inserted against the biasing force of the compression springs 83, The key has to move inwards until the spigot members 68 are within the cover 4 and are located in the channels 67 of the drive securing means. The key can be rotated, so rotating the boss 26 of the drive securing means and the drive unit connected thereto. The key 52 is retained within the cover when the drive unit has been partially rotated. The key may be removed from the cover at the zero position or once the drive unit has been rotated 9QO 180°,270°or360°, It is conceivable that each position may correspond to a different locking position.

The locking mechanism has been developed primarily for use on dosures such as doors but it has been realised that there are a number of alternative applications such as viewing panels. windows etc. Further additional applications are to secure a panel in front of a TV, to secure cupboard doors or to secure a removable door retainer to a door or frame.

This embodiment has been described by way of example only and it will be appreciated that the skifled person may make modifications without departing from the invention,

Claims

CLAIM S1 A mechanism arranged to be fitted to a closure in use as a locking mechanism, the locking mechanism being operable from a first side of the closure and having: a drive means arranged to be inserted in the closure and a fixable cover comprising a front face and a rear portion arranged to be mounted on the first side of the closure over the drive means.the drive means being arranged to engage with a locking means in the closure and abk to move the locking means in use between an open position and a ocked position wherein the drive means comprises a drive unit arranged to operate the locking means and a drive securing means wherein the drive securing means comprises a rotatable body which in use is concealed by the cover and a number of locking elements located in the rotatabk body and biased away from the drive unit towards the cover, the cover having at least one aperture in which the locking elements are received such that a first end of each locking element is substantiafly flush with a front face of the cover in a first secured position, the ocking mechanism being arranged to be operabk by a key to move the locking elements against the bias and towards the drive unit to a second active position in which the key is able to rotate thc drive securing means such that thc drive unit can move the locking means between the open and the closed position.
2. A locking mechanism according to claim 1, wherein biasing means are provided to bias the elements away from the drive unit.
3, A locking mechanism according to claim 2. whcrcin the biasing means are compression springs.
4. A locking mechanism according to any one of claims 1 to 3, wherein the locking mechanism comprises a centrM key guide locator and a number of radial locking elements.
5. A locking mechanism according to claim 4, comprising a central guide element and a four radia' ocking elements.
6. A locking mechanism according to any preceding claim, wherein there is a plurality of locking elements and the ekments may be the same or may have different shapes.

7, A locking mechanism according to any preceding claim, in which the locking mechanism is blind on a second side of thc closurc or in which a means for operating the locking means is provided on a second side of the closure.

8, A locking mechanism according to any preceding claim, wherein the cover has a circular aperture and a number of radial extensions arranged to receive the locking elements, 9, A ocking mechanism according to any preceding daim wherein the ock is an anti-ligature lock.10. A key arranged to operate a mechanism according to any one of claims I to 9, wherein the key comprises a handk. a shaft and a key head and wherein the key head further comprises a numbcr of extending projcctions arranged to cooperate with a respective aperture in the cover and each extending projection is arranged to act on and move a respective locking clement located in the respective aperture such that the respective ocking elements can be moved against the bias towards the drive unit such that the drivc unit can move thc locking means bctwccn the open and thc closcd position.11, A key according to claim 10, wherein the key head comprises a stem having a number of radially extending spigot members spaced around the stem and adapted to cngagc the locking clcmcnts.12, A key according to claim tO, wherein the spigot members are spaced from the key head by a distance at least as great as a thickness of the cover, 13. A kit of parts comprising at least one of a mechanism in accordance with any one of claims I to 9, and a key in accordance with any one of claims 10 to 12.14. A lock comprising a mechanism in accordance with any one of claim 1 to 9, a key in accordance with any one of claims tO to 12 and a locking means.15. A lock in accordance with claim 14, wherein the locking means comprises a latch, a dead-bolt or a sash-lock, 16. A method of locking or unlocking a closure comprising fitting a mechanism in accordance with onc of claims 1 or 3 to 9 as dcpcndcnt on claim 1 in the closurc, fitting the cover to a first side of the closure, and introducing a key in accordance with one of claims 10 to 12 to the locking mechanism such that the key engages the locking elements of the drive securing means and moves the locking elements towards the drive unit to an active position, and operating the locking means to lock and unlock the closure.17. A method of locking or unlocking a closure in accordance with claim 16, wherein the key has a stem comprising a central key locator adapted to engage and locate with a key locator guide in the locking mechanism and wherein the stem is further provided with a number of projections spaced around the key locator and arranged to cooperate with the respective radial extensions of an aperture on the cover.18. A method of locking or unlocking a closure in accordance with claim 16, wherein each projection is in the form of a spigot member extending from the central stem and the spigot members are arranged to be received within the drive member such that the drive member can be rotated relative to the cover and the locking means can be operated.19. A method of locking or unlocking a closure in accordance with claim 17, wherein each of the locking elements is moved against the bias such that the locking elements are clear of the cover and the spigot members are received in the drive securing means clear of the cover.20. A locking mechanism substantially as described herein with reference to and as illustrated in the accompanying drawings.21. A key substantially as described herein with reference to reference to and as i flustrated in the accompanying drawings.22. A method of locking or uiiocking a closure substantiaHv as described herein with reference to and as illustrated in the accompanying drawings.