Openable closures such as doors, windows or the like are conventionally provided with releasable closure mechanisms consisting of a closure bolt, latch or catch piece, typically within the door or window frame, and adapted to be retractably inserted into a receiving aperture in a door jamb or window surround by action of a rotating spindle generally passing through and perpendicular to the door or window and caused to rotate by operation of a suitable handle.

It sometimes proves necessary to secure such closures against opening by unauthorised persons. This has particularly been the case in relation to external domestic doors. Traditionally, this has been done by the provision of bolts and locks fitted to the closure in addition to the handle. These have often operated on similar principles, for example involving sliding portions securable in recesses in the door jamb or window frame to prevent opening of the door, but are set up to be accessible only from one side thereof (eg to be operated from the inside only) and/or to be operated by a key or other security device.

An increased need for security, particularly in domestic situations, has become progressively more important in recent years. To provide such additional security, two developments in particular have been notable. First, mechanisms have been developed which incorporate a lock into the handle of external doors to selectively lock the handle and prevent its unauthorised use. Second, attention has been increasingly paid to providing means to lock internal door handles and to provide locks on window handles. In each of these cases, the same general problem arises, in that it is necessary to develop a device which is effective in preventing unauthorised operation of the handle of the door, window or other closure. However, there is a general desire that such devices should be relatively simple to operate. Generally speaking, security devices whose operation proves too complex are unlikely to be used regularly, particularly in a domestic situation.

A number of prior art devices have been proposed to afford additional security by selectively preventing use of door and window handles. These operate along several general principles. First, devices are proposed which are designed to engage the door or window bolt or latch in a locked closed position. Second, mechanisms have been proposed which selectively disengage the spindle (and hence the handle) from the bolt or latch. Third, mechanisms have been proposed which lock the spindle itself, preventing its rotation.

None of these approaches are entirely satisfactory. They are all likely to require specifically designed mechanisms of spindle and/or latch/bolt, which is likely to increase complexity and therefore result in more opportunities for malfunction, difficulties in fitment and increased costs. In particular, there is obvious danger if a lock should fail in locked position. Moreover, the need for special components and/or for specific grooves or apertures or the like to be

cut in existing components limits the effectiveness of such devices for after market fitment to existing door and window handles.

A variation on the principle of locking the spindle which overcomes some of the disadvantages of prior art devices, and which can be fitted to existing handles, is described in GB2209367. A sliding bolt plate is used, the end of which can be slid into position whereat it engages against the spindle to restrict its rotation. However, this arrangement has limitations, not least in that it is easily forced. Excessive rotational force applied to the spindle, for example by an intruder, will tend to urge the bolt plate back out of its engaged position.

It is an object of the present invention to provide a locking mechanism for a handle on an openable closure such as a door or window which mitigates some or all of the above disadvantages.

It is a particular object of the present invention to provide a locking mechanism adapted for simple action to secure such a handle, in particular as a secondary security device either as an additional locking mechanism on a closure provided with more conventional security devices, or as a locking mechanism on a closure conventionally not provided with any such security devices.

It is a particular object of the present invention to provide a locking mechanism suitable as a secondary security device in a domestic situation, for example for internal doors and windows.

It is a particular object of the invention to provide a locking mechanism suitable for incorporation into existing handle designs, whether as an integral unit therewith or as an after market fitment to existing handles.

Thus, in accordance with the present invention in its broadest aspect there is provided a locking mechanism for a handle of a closure which is secured by a catch openable by action of the handle, acting via a rotating spindle, to effect movement of the catch between a fastened and a released position, the locking mechanism comprising a generally flat bolt plate adapted to be slidingly engaged generally parallel to a surface of said closure and comprising a plate portion defining an aperture surrounding said spindle in use, wherein the aperture is so shaped that the bolt plate is slidable from a first position whereat in use the spindle is able to freely rotate within the aperture to a second position whereat in use the plate portion engages the spindle to restrict or prevent rotation thereof, and wherein a resilient bolt plate catch is provided to selectively and releasably retain the bolt plate in the first or second position.

In accordance with the present invention, simple movement of the bolt plate between its first and second positions, and in particular simple linear movement, is sufficient to selectively engage and disengage the spindle, and thus selectively to lock and unlock the handle/spindle/catch arrangement of the closure. Unlike most prior art systems, no modification is required to the catch, spindle or handle. The device is suitable for use with any standard catch/spindle/handle assembly, being provided either at the time the handle is applied for example as part of an integral unit or as an after market modification to be made to an existing handle in situ.

Because the aperture in the plate portion of the bolt plate in accordance with the present invention entirely surrounds the spindle the arrangement is much

more secure than that proposed in GB2209367. Once the bolt plate is incorporated into a handle/spindle/catch assembly, it cannot be removed slidably, but only by complete disassembly of the handle arrangement.

Moreover, the locking mechanism is much more effective, and less prone to slipping out of position or being forced by an unauthorised user, because of this configuration in conjunction with a resilient bolt plate catch provided to define and locate the bolt plate selectively at the first and second positions.

The locking mechanism in accordance with the present invention is suitable for fitment to any closure, such as a door, window or the like, which is releasably opened by means of a latch closure mechanism operated by a rotating spindle arrangement. In particular, the mechanism may be applied to domestic doors and windows, whether externally or internally.

The mechanism may be applied to handles on such doors or windows where such handles are provided on one side only, or whether the spindle goes through the thickness of the door to be operated by a handle on both sides. In the latter case, the locking mechanism may be incorporated on one or both sides as desired.

The resilient bolt plate catch preferably comprises one or more mutually cooperable projection and recess arrangements, wherein at least one of the projection and recess is flexibly resilient, to serve to locate the bolt plate at the first or second position, but to release under application of a sufficient sliding force to allow the bolt plate to move between the first and the second position.

Preferably, the two positions are defined by one or more combinations of a pair of projections and a single recess or vice versa. Conveniently, one of the projection and recess is provided in the bolt plate, and especially at an edge of

the plate portion thereof, and the complementary recess or projection is provided adjacent thereto.

Preferably, the bolt plate is provided within a housing defining a cavity in which the plate portion can slide from the first to the second position, the cavity defining the permitted extent of the slide thereof. Preferably, the resilient bolt plate catch comprises a mutually cooperable projection and recess arrangement, wherein one of the projection and recess is provided at an edge of the plate portion within the cavity, and the complementary recess or projection is provided at an edge of the housing defining the cavity adjacent thereto.

In particular, the projection is resilient to provide a releasable snap fit engagement into one or more complementary recess to locate and retain the bolt plate in position. The resilient projection may comprise a projection of resilient material, and or a projecting portion mounted on or incorporated integrally into resilient material, for example an armature or leaf spring.

In a preferred arrangement, a resilient projection is provided at an edge of the cavity adjacent to the plate portion within the cavity, selectively engageable with one of two cavities at an edge of the plate portion serving respectively to locate the plate portion in the first and the second position. In a particularly preferred embodiment the resilient projection may comprise an engaging portion sized to fit into the said cavities and a flexibly resilient supporting portion such as a leaf spring or armature portion, and a catch cavity may be provided in the housing into which the engaging portion may be urged against the resilience of the supporting portion to release the plate portion under action of a sliding force to the bolt plate.

Save for this provision for sliding, preferably in a single linear direction, and for the provision for a bolt plate catch, the cavity provides for a snug engagement of the plate portion to limit unwanted movement in other directions.

In one embodiment, the housing comprises a housing plate with a cavity portion accommodating the plate portion of the bolt such as to allow for such sliding.

In a preferred embodiment, the housing plate and bolt plate are of generally similar thickness, and the housing further comprises cover plates on either side thereof fixedly secured to the housing plate so as to locate the base plate slidingly within the cavity therein defined. Each such cover plate needs to be provided with an aperture which will not interfere with the rotation of the spindle, and in particular has an aperture adapted to be fixedly mounted relative to the spindle and housing plate, with the bolt plate slidable therein, so that only movement of the bolt plate acts selectively to restrict rotation of the spindle.

The bolt plate preferably includes a projecting portion projecting externally of any housing to serve as a handle to effect linear movement of the plate portion between the first and the second positions to effect selective locking of the spindle.

The aperture in the bolt plate is so configured and adapted as to restrict the movement of the spindle in the second position but to leave it free to rotate in the first position.

In a simple embodiment, the aperture in the plate portion may comprise an area of larger extent adapted to surround the spindle at the first position so that the spindle is able to rotate freely, and an area of smaller extent adapted to be surrounding the spindle at the second position so as to engage the spindle to restrict or prevent rotation thereof.

Typically, the aperture in the second position will be suitably sized and shaped to effect at least partly a snug engagement around the spindle. The shape of the aperture at the point where it seats around the spindle in the second position will thus be dictated by the cross section of the spindle. In many instances, spindles are provided of rectangular, and especially square cross section. The portion of the aperture in the bolt plate which seats around the spindle when the bolt plate is in the second position will be shaped and sized accordingly.

Additionally or alternatively the aperture in the plate portion may incorporate projecting elements positioned such as to lie free of the spindle when the plate portion is in the first position but to engage the spindle, and for example complimentary recesses or apertures therein, when the plate portion is in the second position.

It should be emphasised that the invention in its broadest aspect is considered to be the locking mechanism itself. In accordance with the invention this can be supplied integrally with a handle/spindle/catch assembly for example as a sealed unit and/or separately from the handle and/or as a kit of parts in conjunction with a handle/spindle/catch assembly for use as an optional accessory with a standard handle and/or as an accessory for after market fitment to a standard handle already in place.

In a further aspect of the invention, there is provided a handle assembly for an openable closure such as a door, window or the like comprising a catch adapted for mounting for linear movements parallel to the closure surface, for example by being retained within the thickness of the closure or upon the surface thereof, between a retracted position and an extended position in which it engages a socket in the frame surrounding the said closure to effect closure thereof, a spindle extending generally perpendicularly to the catch and operably coupled thereto such that rotation of the spindle causes retraction of the catch, a handle means mounted upon a surface of the closure and accessible externally therefrom to effect rotation of the spindle, and a bolt plate as hereinbefore described mounted upon the closure such that its aperture surrounds the said spindle, and such as to be slidable from a first position wherein the spindle is able to freely rotate within the aperture to a second position wherein the plate portion engages the spindle to restrict or prevent rotation thereof.

In particular, the bolt plate is provided with a housing as above described, adapted to be mounted directly upon the surface of the closure immediately below the handle.

In a preferred embodiment the aperture in the bolt portion comprises an area of smaller extent adapted to seat around the spindle when the bolt plate is in the second position and restrict or prevent its movement thereof.

The bolt plate and/or any housing may be suitably sized and shaped to correspond to the handle, for example being square, circular or oval to correspond to or complement the design of the mounting plate of an existing handle. Bolt plates and housing where applicable may be provided in a

plurality of sizes and designs and a plurality of materials, to match or complement a range of handle designs.

In accordance with a further aspect of the invention there is provided a kit of parts comprising a bolt plate as hereinbefore described, optionally a housing as hereinbefore described, and a handle, spindle and catch of conventional design suitable for the fitment of a lockable handle mechanism in accordance with the invention to a closure such as a door, window or the like.

In accordance with a further aspect of the invention there is provided a method of fitment, and in particular fitment as an after market accessory in situ, of a locking mechanism to a handle of a closure such as door, window or the like, which is secured by a catch openable by action of the handle via a rotating spindle to effect movement of the catch between a fastened and a released position, the method comprising the steps of disassembling the handle, fitting a bolt plate as hereinbefore described onto the surface of the closure such that the aperture in the bolt portion thereof surrounds the spindle of the handle, and such as to be slidable from a first position wherein the spindle is able to freely rotate within the aperture to a second position wherein the plate portion engages the spindle to restrict or prevent rotation thereof, and reassembling the handle assembly.

The invention will now be described by way of example only with reference to Figures 1 to 3 of the accompanying drawings wherein: Figure 1 is an exploded view of a door handle assembly fitted with a locking device in accordance with the invention; Figure 2 is an alternative engagement arrangement for the locking device of figure 1;

Figure 3 is the assembled locking device and housing of Figure 1 shown respectively in an unlocked (Figure 3a) and a locked (Figure 3b) position.

Illustrated in Figure 1, a bolt plate and housing in accordance with the invention is shown as used in conjunction with a simple door handle arrangement, not otherwise provided with a lock, such as might be typical in any internal domestic door.

Figure 1 illustrates a door (1) internally to which is mounted a catch (2) in conventional manner, which will project into and engage with a complementary recess in the door frame (not shown). Translational movement of the catch (2) is effected by rotational movement of the square section steel spindle (3), which when fully assembled will be connected to and rotation effected by the handle (4).

The locking assembly comprises housing cover/spacer plates (11,14), housing plate (12), and bolt plate (13). The cover/spacer plates (11,14) and housing plate (12) are fixedly mounted together with the bolt plate (13) slidable therein, and are fixedly mounted onto the surface of the door, such that the bolt plate is slidable relative to the door. Fixing is by means of screws (7) through apertures (8) in the various plates into screw sites (9) in the door.

In this configuration, apertures (16) in the cover/spacer plates (11,14) allow the spindle (3) to project through and rotate freely. A bolt portion (18) of the bolt plate (13) is able to slide laterally within a cavity (17) in the housing plate (12). In the position shown (bolt plate in its first position), an upper part (19a) of an aperture in the bolt plate portion (17) surrounds the projecting spindle when the whole is assembled, the upper part of the aperture being of such extent that it is free to rotate. In a second position, effected by sliding the bolt

plate (13) upwards, the square aperture (19b) surrounds and engages upon the spindle (3) and prevents its rotation. Movement from the one position to the other is assisted by the handle (20).

The housing plate (12) incorporates a bolt plate catch which serves to locate the bolt plate in one or other of these positions and prevents unwanted movement for example if jolted or under gravity. Two alternative catch arrangements are shown in insets A and B on figure 1.

In inset A, the bolt plate catch shown consists of a projection (21) to engage one of the recesses (22) in the bolt plate. These locate the bolt plate in one or other of the two positions against minor jolting forces, gravity etc. Under a more positive sliding force, the resilient arm (23) flexes so that the projection (21) is urged into the cavity (24), releasing the bolt plate, and providing for releasable snap fit retention of the plate in either position. The whole armature arrangement is fabricated from a suitably resilient plastic.

In inset B, a generally similar arrangement is shown. The bolt catch however comprised a projection (26) integral to a leaf spring (27) which again engages one of the recesses (22) in the bolt plate to locate it in position. Under a more positive sliding force, leaf spring (27) flexes into the cavity (24) releasing the bolt plate.

In figure 2 a further alternative arrangement is shown. The bolt plate (31) has a generally W-shaped recess (32) providing two engagement points (33). As in inset B the bolt catch comprised a projection (26) integral to a leaf spring (27) which engages one of the recesses (22) in the bolt plate to locate it in position. The catch is spring biased into the intended position and will not slide freely and accidentally out. However under a more positive deliberate

sliding force, the leaf spring (27) flexes into the cavity (24) releasing the bolt plate and allowing it to be slid to the alternative position were it will again be stably retained when the sliding force is removed.

In the illustrated embodiments, the bolt plate is fabricated from suitably machined brass plate. The housing plate is a one piece moulding of suitable plastics material. In the embodiment shown in inset A, this includes an integral bolt plate catch relying upon the inherent resilience of the material from which it is fabricated, and the cover plates are similarly moulded from suitable plastics material.

Other materials will readily suggest themselves. The primary consideration is that the bolt plate in particular should be sufficiently robust for the purpose envisaged. The bolt plate in particular is accordingly preferably fabricated from metallic materials such as the brass in the example, mild steel, aluminium or the like. The other components may be fabricated from similar materials (eg to match the look of the door), or from other suitable materials such as the plastic mouldings of the embodiment.

Operation of the lock is illustrated in a little more detail in Figure 2. In Figure 2, the housing and bolt assembly is shown complete in plan view. In each case, a small portion of the bolt plate is visible through an aperture (16) in the cover plate (14). In Figure 2a the lock is open, with the bolt plate slid into the first, downmost position so that the upper aperture portion (19a) is in position around the spindle (not shown) which can then freely rotate. In Figure 2b, the bolt plate is in the second, uppermost position, so that the lower aperture portion (19b) is in position and engages upon and generally surrounds the square cross section spindle to prevent its rotation. In each case a resilient catch (not shown) of any suitable design retains the plate securely in the

correct position by default, but allows movement between the two positions when a deliberate sliding force is applied.

In this way, the whole assembly provides a simple, stable and effective lock on the spindle which is easily engaged and released by a user.